Name: Advances in Radioactive Isotope Science
Start: 2017-05-28T09:00:00-06:00
End: 2017-06-02T16:00:00-06:00
Location: No location set

Advances in Radioactive Isotope Science

from Sunday, May 28, 2017 (9:00 AM) to Friday, June 2, 2017 (4:00 PM)

Monday, May 22, 2017
Tuesday, May 23, 2017
Wednesday, May 24, 2017
Thursday, May 25, 2017
Friday, May 26, 2017
Saturday, May 27, 2017
Sunday, May 28, 2017

2:00 PM On-Site Registration Open
On-Site Registration Open
2:00 PM - 6:00 PM

6:00 PM Welcome Reception
Welcome Reception
6:00 PM - 9:00 PM

Monday, May 29, 2017

8:55 AM Logistics and Welcome
Logistics and Welcome
8:55 AM - 9:05 AM
9:05 AM QED and the Hyperfine-structure Puzzle in Hydrogen-like and Lithium-like Bismuth - Wilfried Nörtershäuser (TU Darmstadt)
QED and the Hyperfine-structure Puzzle in Hydrogen-like and Lithium-like Bismuth
- Wilfried Nörtershäuser (TU Darmstadt)
9:05 AM - 9:30 AM
Room: Plenary-Longs Peak The possibility of testing quantum electrodynamics (QED) in very strong fields by laser spectroscopy on heavy highly charged ions has been opened by the first observation of the hyperfine splitting in hydrogen-like bismuth in 1994 [Klaft et al. Phys. Rev. Lett 73, 2428 (1994)]. The electrons in these systems experience the strongest magnetic fields available in the laboratory, but the significance as a test for QED of this and following experiments on other species was limited by the unknown magnetic moment distribution inside the nucleus. However, it was suggested that a so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like ions of the same isotope can be used to cancel nuclear structure effects and provide an accurate test of QED [Shabaev et al., Phys. Rev. Lett. 86, 3959 (2001)]. The transition in Li-like Bismuth was observed for the first time in 2011 at the Experimental Storage Ring ESR located at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt [M. Lochmann et al., Phys. Rev. A 90, 030501 (2014)]. Yet the accuracy of the result was limited by the calibration of the electron cooler voltage, determining the ion velocity. Here, we report on improved laser spectroscopic measurements on bismuth ions of both charge states ( 209Bi82+ and 209Bi80+) at the ESR. The accuracy was improved by about an order of magnitude compared to the first observation in 2011. We will present the measured transition energies of both hydrogen- and lithium-like bismuth and the experimentally determined value for the specific difference in 209Bi which is in contradiction with theoretical predictions. Possible reasons will be discussed and ways to further investigate this puzzle by laser spectroscopy on radioactive species will be discussed.
9:30 AM Ion Traps for Precision Experiments at TRIUMF - Anna Kwiatkowski (TRIUMF)
Ion Traps for Precision Experiments at TRIUMF
- Anna Kwiatkowski (TRIUMF)
9:30 AM - 9:55 AM
Room: Plenary-Longs Peak Ion traps are of growing popularity at rare-isotope-beam facilities due to their textbook-like conditions and tailorability. This versatility is exemplified at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) facility, where ion traps are used for beam preparation and high-precision measurements. Penning trap mass spectrometry has provided insight into the evolution of the N = 20 shell in the island of inversion, nucleosynthesis via the r-process, and the unitarity of the quark-mixing matrix. In-trap decay spectroscopy research has focused on branching ratios to investigate the double-beta-decay problem and now includes studies of the role of electronic structure in nuclear decay. Moreover, investigations with preparatory traps are being used to extend the reach of TITAN, by reducing beam contamination, improving beam availability beyond ISOL-produced beams, and increasing ion bunch size. A selection of recent highlights and advances will be presented.
9:55 AM The Search for Fundamental Symmetry Violation in Radium Nuclei - Matthew Dietrich (Argonne National Lab)
The Search for Fundamental Symmetry Violation in Radium Nuclei
- Matthew Dietrich (Argonne National Lab)
9:55 AM - 10:20 AM
Room: Plenary-Longs Peak Electric dipole moments (EDMs) are signatures of time-reversal, parity, and charge-parity (CP) violation, which makes them a sensitive probe of expected new physics beyond the Standard Model, such as supersymmetry. No experiment has yet observed a non-zero EDM to challenge the Standard Model. Due to its large nuclear octupole deformation and high atomic mass, the radioactive Ra-225 isotope is a favorable EDM case; it is particularly sensitive to CP-violating interactions in the nuclear medium. We have developed a cold-atom approach of measuring the atomic EDM of Ra-225 atoms held stationary in an optical dipole trap. We previously demonstrated this technique with an initial experimental upper limit of |d(225Ra)| < 5e-22 e-cm (95% C.L.), and have since improved this limit 36-fold to 1.4e-23 e-cm. This is not only the first time laser-cooled atoms have been used to measure an EDM, but also the first time the EDM of any octupole deformed species has been measured. Upcoming improvements are expected to dramatically improve our sensitivity, and significantly improve on the search for new physics in several sectors. This work is supported by U.S. DOE, Office of Science, Office of Nuclear Physics, under contract DE-AC02-06CH11357.
10:20 AM Magnetic Moment Measurement of Isomeric State of Cu-75 Using Spin-aligned RI Beam at RIBF - Yuichi Ichikawa (RIKEN Nishina Center)
Magnetic Moment Measurement of Isomeric State of Cu-75 Using Spin-aligned RI Beam at RIBF
- Yuichi Ichikawa (RIKEN Nishina Center)
10:20 AM - 10:45 AM
Room: Plenary-Longs Peak Unstable nuclei with extremely unbalanced proton-to-neutron ratio often exhibit evolved shell structure and collectivity such as vibrated/deformed shapes, which compete with each other to determine the resultant structure. The nuclear magnetic moment is one of the important observables with which we can catch a glimpse into the competition. A technique to orient the nuclear spin is necessary for the magnetic moment measurement. Recently a scheme of the two-step reaction was developed to produce high spin alignment (rank-two orientation) in RI beams [1]. This scheme realizes high spin alignment as well as high production yield of RI beams by combining a technique of momentum dispersion matching at the beam transportation. It has opened up opportunities to produce spin alignment for unstable nuclei, for which the spin alignment would have tended to significantly attenuate if the conventional scheme was employed because of the mass difference between a projectile and the final fragment. The two-step scheme was employed in the magnetic moment measurement of the isomeric state of the neutron-rich nucleus Cu-75. The experiment was carried out at RIBF. The Cu-75 beam with spin alignment reaching 30% was produced from a primary beam of U-238 via an intermediate product of Zn-76. For the measurement of the magnetic moment, a method of time-differential perturbed angular distribution (TDPAD) was employed. Owing to the high spin alignment realized with the two-step scheme, the oscillation in the TDPAD spectrum was observed with significance larger than 5 sigma. The magnetic moment of the 66.2-keV isomer, which is one of the two low-lying isomers in Cu-75, was determined for the first time. In this talk, the magnetic moment measurement employing the two-step scheme will be introduced and the result of the experiment of Cu-75 will be presented. Discussions on the competition between shape and shell at the neutron-rich Cu isotopes, through the precise analysis of the magnetic moment with a help of the state-of-the-art Monte Carlo shell model calculation, will also be given. References: [1] Y. Ichikawa et al., Nature Phys. 8, 918 (2012).
10:45 AM Coffee Break
Coffee Break
10:45 AM - 11:00 AM
Room: Shavano & Torreys Peak Room
11:00 AM Explosive Nucleosynthesis of Heavy Elements: An Astrophysical and Nuclear Physics Challenge - Gabriel Martinez-Pinedo (GSI Darmstadt and TU Darmstadt)
Explosive Nucleosynthesis of Heavy Elements: An Astrophysical and Nuclear Physics Challenge
- Gabriel Martinez-Pinedo (GSI Darmstadt and TU Darmstadt)
11:00 AM - 11:25 AM
Room: Plenary-Longs Peak Half of the elements heavier than iron are produced by the r process under extreme conditions. To identify its site remains one of the major challenges in nuclear astrophysics. Advances in the description of neutrino-matter interactions and its implementation in core-collapse supernova modelling have lead to the conclusion that supernova explosions only contribute to the production of elements with Z < 50. Compact binary mergers are currently considered the best candidate for the main r-process site. These events are expected to produce gravitational waves, likely to be observed by the LIGO collaboration, and eject large amounts of neutron-rich material where the r process operates. In this talk, I will discuss the important role of nuclear physics to determine the r-process yields from compact binary mergers. In addition to neutron captures and beta decay, fission rates and yields of superheavy neutron-rich nuclei are fundamental to understand the r-process dynamics and nucleosynthesis. Mergers constitute also ideal candidates to directly observe the r-process via an electromagnetic transient due to the radioactive decay of r-process material. This type of event, known as kilonova, may have already been observed associated with the gamma-ray burst GRB 130603B.
11:25 AM Advances in Explosive Nuclear Astropysics - Gavin Lotay (University of Surrey)
Advances in Explosive Nuclear Astropysics
- Gavin Lotay (University of Surrey)
11:25 AM - 11:50 AM
Room: Plenary-Longs Peak Breathtaking results from the Planck satellite mission and Hubble space telescope have highlighted the key role modern Astronomy is playing for our understanding of Big Bang Cosmology. However, not so widely publicized is the similar wealth of observational data now available on explosive stellar phenomena, such as X-ray bursts, novae and Supernovae. These astronomical events are responsible for the synthesis of almost all the chemical elements we find on Earth and observe in our Galaxy, as well as energy generation throughout the cosmos. Regrettably, understanding the latest collection of observational data is severely hindered by the current, large uncertainties in the underlying nuclear physics processes that drive such stellar scenarios. In order to resolve this issue, it is becoming increasingly clear that there is a need to explore the unknown properties and reactions of nuclei away from the line of stability. Consequently, state-of-the-art radioactive beam facilities have become terrestrial laboratories for the reproduction of astrophysical reactions that occur in explosive stellar events. In this talk, both direct and indirect methods for studying key astrophysical reactions using radioactive beams will be discussed.
11:50 AM Direct Measurements of α-capture Cross Sections Relevant for Nuclear Astrophysics - Melina Avila (Argonne National Laboratory)
Direct Measurements of α-capture Cross Sections Relevant for Nuclear Astrophysics
- Melina Avila (Argonne National Laboratory)
11:50 AM - 12:15 PM
Room: Plenary-Longs Peak Since helium is the second most abundant element in the universe, there are numerous reaction rates involving α-particles that play a key role in nuclear astrophysics. For instance, some (α,p) reactions have been found to be fundamental for the understanding of X-ray bursts and the production of 44Ti in core-collapse supernovae. Furthermore, some (α,n) reactions are considered to be important neutron sources in different astrophysical scenarios. Direct measurements of these reactions at relevant astrophysical energies are experimentally challenging because of their small cross sections and the intensity limitation of radioactive beams. In this talk I will describe a novel technique to study (α,p) and (α,n) reactions using a Multi-Sampling Ionization Chamber (MUSIC), a simple and highly efficient active target system with a segmented anode that allows the investigation of a large energy range of the excitation function. Recent results on the direct measurement of (α,n) and (α,p) reactions in the MUSIC detector will be presented. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. This research used resources of ANL’s ATLAS facility, which is a DOE Office of Science User Facility.
12:15 PM Neutron Capture Reactions for the Astrophysical r process - Artemis Spyrou (NSCL/MSU)
Neutron Capture Reactions for the Astrophysical r process
- Artemis Spyrou (NSCL/MSU)
12:15 PM - 12:40 PM
Room: Plenary-Longs Peak The astrophysical r process is responsible for the synthesis of about half of the isotopes of the heavy elements. Although the general characteristics of the process have been known for a while, the astrophysical site where it takes place has not been unambiguously determined. Efforts to better understand this important process span across many fields, including astronomical observations of metal-poor stars, modeling of the possible scenarios, sensitivity studies, nuclear theory calculations and nuclear experiments. One of the nuclear inputs that have a large impact on the final abundance calculations is neutron-capture reaction rates. These reactions are practically unconstrained far from stability due to the difficulty in studying them with direct techniques. As a result, astrophysical calculations have to rely on theoretical models, which differ from each other by factors of 10-1000. Therefore, indirect experimental approaches are required, and this talk will present the development of a new technique to experimentally constrain these important (n,γ) reaction rates far from stability. The relevant experiments were done at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University using the γ-calorimeter SuN. New results in the mass region of A=70 and the impact on r-process calculations will be presented.
12:40 PM Lunch Break
Lunch Break
12:40 PM - 2:00 PM
2:00 PM Unveiling New Features in the Exotic Landscape of Light Nuclei with Direct Reactions - Rituparna Kanungo (Saint Mary's University)
Unveiling New Features in the Exotic Landscape of Light Nuclei with Direct Reactions
- Rituparna Kanungo (Saint Mary's University)
2:00 PM - 2:25 PM
Room: Plenary-Longs Peak Radioactive (RI) beams are allowing us to uncover the unknown properties of nuclei at the extremes of nuclear binding. This is leading to revelation of new phenomena associated with exotic structures like nuclear halo and skin that stretch beyond the bounds of our conventional knowledge. The evolution of neutron skin/surface in neutron-rich nuclei can cause mutation of the nuclear shell structure and give rise to exotic excitation modes such as soft dipole resonance states. The new features in exotic nuclei challenge our understanding of the nuclear force. Reaction spectroscopy with both ISOL and in-flight RI beams offer complementary avenues that have different sensitivities to different characteristics of the exotic nuclei. The presentation will discuss how direct reactions with the low-energy re-accelerated beams at TRIUMF and the IRIS reaction spectroscopy facility with solid H2/D2 targets have opened access for obtaining some precise spectroscopic information of exotic nuclei. Recent explorations of unbound states in light nuclei around the drip-lines will be presented. It will be shown that the low-energy scattering opens a new avenue to constrain the nuclear force with its ability of connecting to the ab initio theory. The relativistic energy in-flight beams allow us to probe into the nucleon distribution and nuclear radii that characterize the exotic nuclear halo and skin. Recent measurements at the GSI fragment separator FRS will be reported to elucidate the development of neutron skin and evolution of nuclear halo correlations in neutron-rich nuclei.
2:25 PM Four-body Continuum Effects in d+11Be Elastic Scattering - Pierre Descouvemont (Universite Libre de Bruxelles)
Four-body Continuum Effects in d+11Be Elastic Scattering
- Pierre Descouvemont (Universite Libre de Bruxelles)
2:25 PM - 2:50 PM
Room: Plenary-Longs Peak The main goal of the Continuum Discretized Coupled Channel (CDCC) method is to solve the Schrödinger equation for reactions where the projectile presents a cluster structure, and a low dissociation energy. The CDCC method has been introduced forty years ago [1] to describe deuteron induced reactions. Owing to the low binding energy of the deuteron, it was shown that including continuum channels significantly improves the description of d+nucleus elastic cross sections [1, 2]. The simplest variant of CDCC describes scattering of a two-body nucleus with a structureless target, but extensions to three-body projectiles have been performed recently (see, for example, ref. [3]). The projectile continuum is approximated by a finite number of square-integrable states, up to a given truncation energy. We present here a new development of the CDCC method, which aims at describing reactions where the projectile and the target have a low separation energy. This leads to four-body (or more) calculations. Since continuum states are included in both colliding nuclei, the number of channels can be extremely large. We solve the coupled-channel system by using the R-matrix method on a Lagrange mesh [4]. A first application is presented for d+11Be elastic scattering and breakup, which have been measured recently at Ecm=45.5 MeV [5]. The 2H and 11Be nuclei are defined by 2H=p+n and 11Be=10Be+n structures. We choose the Minnesota potential [6] as nucleon-nucleon interaction, and the Koning-Delaroche global potential [7] as nucleon-10Be optical potentials. We show that including continuum states of 2H and of 11Be is necessary to reproduce well the experimental data. References: [1] G. H. Rawitscher, Phys. Rev. C9 (1974) 2210. [2] M. Yahiro et al., Prog. Theor. Phys. Suppl. 89 (1986) 32. [3] T. Matsumoto et al., Phys. Rev. C70 (2004) 061601. [4] P. Descouvemont and D. Baye, Rep. Prog. Phys. 73, (2010) 036301. [5] J. Chen et al. , Phys. Rev. C94 (2016) 064620. [6] D.R. Thompson, M. LeMere, and Y.C. Tang, Nucl. Phys. A286 (1977) 53. [7] A.J. Koning and J.P. Delaroche, Nucl. Phys. A713 (2003) 231.
2:50 PM Transfer Reactions with Isomeric Beams - Sergio Almaraz-Calderon (Florida State University)
Transfer Reactions with Isomeric Beams
- Sergio Almaraz-Calderon (Florida State University)
2:50 PM - 3:15 PM
Room: Plenary-Longs Peak Nuclear reactions induced by isomeric beams have long been considered an extremely attractive tool for nuclear structure, nuclear reactions and nuclear astrophysics studies. One of the most interesting cases is in 26Al, where a 0+ isomer is located 228 keV above the 5+ ground state. Proton captures on both, the ground state and the isomeric state, could have a direct impact on the abundance of 26Al in the Galaxy. In this talk, I will discuss our efforts to develop and characterize an isomeric 26Alm beam with sufficient intensity, purity, high isomer-to-ground state ratio and energy resolution to study transfer reactions induced by the 0+ isomer in 26Al. Results on the measurement of the 26Alm(d,p)27Al reaction and its astrophysical implications will also be presented.
3:15 PM Isospin Symmetry Studies Using Direct Reactions on Fragmentation Beams - Michael Bentley (University of York)
Isospin Symmetry Studies Using Direct Reactions on Fragmentation Beams
- Michael Bentley (University of York)
3:15 PM - 3:40 PM
Room: Plenary-Longs Peak The neutron-proton exchange (isospin) symmetry results in striking symmetries in nuclear behavior between isobaric analogue states (IAS). The very small differences in excitation energy between the IAS can be interpreted in terms of Coulomb, and other isospin-non-conserving, effects. The analysis of these energy differences has been shown to be a sensitive probe of nuclear structure effects and provides stringent tests of model calculations (e.g.[1-5]). New experimental techniques have been applied in the last few years to access excited states in isobaric multiplets of larger isospin through spectroscopic studies of proton-rich nuclei heading towards the proton drip-line. Knockout reactions have recently been shown to provide a successful and versatile technique for accessing states on interest in proton-rich nuclei for isospin-related studies. The direct nature of the 1-nucleon and 2-nucleon knockout mechanism yields selective population specific analogue states within a multiplet, allowing studies of isospin-symmetry breaking - see e.g. [6]. In this talk, the latest results using knockout reactions on radioactive beams at NSCL will be presented, including an analysis of mirrored knockout reactions and population of high-spin states through knockout from a high-spin isomer [7]. Theoretical analysis of both the reaction cross sections and isospin-symmetry breaking effects across the multiplets in the f7/2 shell will be presented. In the shape-coexistence region around A~70, the strongly competing nuclear shapes have been predicted to yield the potential for the breakdown of isospin symmetry across a multiplet (e.g. [8]). To test these ideas, the study of the full A=70 isobaric triplet has been the subject of a number of experimental studies, to examine the extent to which isospin symmetry is retained. The recent identification of excited states in 70Kr [9] now completes this triplet. These data and their interpretation will be presented. References: [1] Bentley and Lenzi, Prog. Part. Nucl. Phys. 59, 497 (2007) [2] Zuker et. al., Phys. Rev. Lett. 89, 142502 (2002) [3] Ekman et al., Mod. Phys. Lett. A20, 2977 (2005) [4] Kaneko et al. Phys. Rev. C89, 031302(R) [5] Bentley et al. Phys. Rev. C92, 024310 (2015) [6] Davies et. al., Phys. Rev. Lett. 111 072501 (2013) [7] Milne et al., Phys. Rev. C 93, 024318 (2016) and Phys. Rev. Lett. 117, 082502 (2016) [8] Petrovici et al. Phys. Rev. C91, 014302 (2015) [9] Debenham et al. Phys. Rev. C94, 054311
3:40 PM np Pairing Viewed From Transfer Reactions - Marlène Assié (IPN)
np Pairing Viewed From Transfer Reactions
- Marlène Assié (IPN)
3:40 PM - 4:05 PM
Room: Plenary-Longs Peak Neutron-proton pairing is the only pairing that can occur in the T=0 and the T=1 isospin channels. T=1 particle-like pairing (n-n or p-p) has been extensively studied unlike T=0 neutron-proton pairing. The over-binding of N=Z nuclei could be one of its manifestation. Neutron-proton pairing can be studied by spectroscopy as in ref.[1].We have studied it through transfer reactions in order to get more insight into the relative intensities of the two aforementioned channels. Indeed, the cross-section of np pair transfer is expected to be enhanced if the number of pairs contributing to the populated channel is important. Neutron-proton pairing is predicted to be more important in N=Z nuclei with high J orbitals so that the best nuclei would belong to the g9/2 shell [2]. However, considering the beam intensities in this region, we have focussed on fp shell nuclei (56Ni and 52Fe). The measurement was performed at GANIL with radioactive beams produced by fragmentation of a 75A MeV 58Ni beam on a 185 mg.cm-2 Be target purified by the LISE spectrometer. An efficient set-up based on the coupling of the MUST2 and TIARA Silicon arrays for charged particle detection with the EXOGAM gamma-ray detector was used. Measuring both 52Fe (N=Z=26) which is a partially occupied 0f7/2 shell nucleus and 56Ni (N=Z=28) which has a fully occupied 0f7/2 shell allowed us to study np pairing along the f7/2 shell and to draw conclusions with respect to the previous studies in the sd-shell. Results on the nature of the n-p pairing will be discussed based on the relative intensities of the 0+ and 1+ states populated in the 56Ni(p,3He)54Co and 52Fe(p,3He)50Mn reactions and on the angular distributions compared with DWBA calculations. References: [1] B. Cederwall et al, Nature 469 (2011) 469. [2] P. van Isäcker et al, Phys. Rev. Lett. 94 (2005) 162502.
4:05 PM Coffee Break
Coffee Break
4:05 PM - 4:35 PM
Room: Shavano & Torreys Peak Room
4:35 PM Direct Detection of the Elusive 229mTh Isomer: Milestone Towards a Nuclear Clock - Benedict Seiferle (Ludwig-Maximilians-Universität München)
Direct Detection of the Elusive 229mTh Isomer: Milestone Towards a Nuclear Clock
- Benedict Seiferle (Ludwig-Maximilians-Universität München)
4:35 PM - 4:55 PM
Room: Plenary-Longs Peak The isomeric first excited state of 229Th possesses the lowest excitation energy of all known nuclei. Its energy has been predicted to be 7.6 eV [1] and could in principle allow to populate this isomeric state with state-of-the-art lasers. This has led to multitude of proposed applications, the best known therein is a nuclear optical clock, that could outperform today’s existing atomic optical clocks. However, progress has so far been hindered by the vague and indirect knowledge of the transition energy and lifetime of the isomeric state. The isomer decays via several decay channels to its ground state, whose strength depends on the electron environment of the nucleus: internal conversion (IC) decay occurs as soon as the binding energy of an electron in the surrounding of the nucleus is below the energy of the isomer. Other decay channels are regular ɣ decay or bound internal conversion, where a bound electronic state is excited. The measurements that led to the first direct detection of the isomer, as well as recent measurements of the internal conversion decay lifetime of neutral 229mTh, are presented in the talk: In our experimental setup, 229mTh is populated via a 2% decay branch of the 233U α decay. Therefore a 233U α recoil source is placed in a buffer gas stopping cell, filled with ultra-pure helium that thermalizes the 229(m)Th recoil ions. The ions are extracted in a gas jet into a segmented radio frequency quadrupole (RFQ) that allows for beam cooling and bunch creation. Behind the RFQ, other daughter nuclei from the 233U decay chain are removed with a quadrupole mass separator and a charge state of the ion can be selected. The 229(m)Th ions are then collected directly on an MCP detector that is used for neutralization of the ions and for the subsequent detection of the internal conversion electron emitted during the ground-state decay of the isomer [2]. With the creation of ion bunches with a width of 10 µs, it was possible to determine the half-life of the internal conversion decay to be 7(1) µs [3]. This work was supported by DFG (Th956/3-1), by the European Union’s Horizon 2020 research and innovation programme under grant agreement 664732 “nuClock” and by the LMU department of Medical Physics via the Maier-Leibnitz Laboratory. References: [1] B.R. Beck et al., PRL 98, 142501 (2007). [2] L. v.d. Wense et al., Nature 533, 47 (2016). [3] B. Seiferle et al., Phys. Rev. Lett. 118, 042501 (2017).
4:55 PM Two-proton Radioactivity - A Nuclear Structure Tool Beyond the Drip Line - Bertram Blank (CEN Bordeaux-Gradignan)
Two-proton Radioactivity - A Nuclear Structure Tool Beyond the Drip Line
- Bertram Blank (CEN Bordeaux-Gradignan)
4:55 PM - 5:15 PM
Room: Plenary-Longs Peak Two-proton radioactivity is the latest nuclear decay mode discovered. It consists of the emission of a pair of protons from a nuclear ground state. According to the definition by V. Goldanskii who was the first to discuss this new type of radioactivity extensively, one-proton radioactivity is not allowed to be an open decay channel for two-proton radioactivity (2p) candidates. In pioneering experiments at GANIL and GSI, this new radioactivity was discovered in 2002 and meanwhile 19Mg, 45Fe, 48Ni and 54Zn are established 2p emitters. These results allowed a detailed comparison with the theoretical models available and showed that, at the level of precision of the experimental data and of the predictive power of the models, nice agreement was obtained. The latest step in the investigation of 2p radioactivity was the use of time-projection chambers to study the decay dynamics via measurements of the individual proton energies and the relative proton-proton emission angle. A first experiment at GANIL and a high-statistics experiment performed at MSU on 45Fe allowed to gain first insights into the decay characteristics by comparison with a three-body model. Meanwhile 54Zn has also been studied with a TPC at GANIL and 2p radioactivity was confirmed for 48Ni at MSU. In a recent experiment at the BigRIPS separator of RIKEN, a new 2p emitter, 67Kr, was discovered and its basic decay characteristics have been established, whereas two other 2p radioactivity candidates, 59Ge and 63Se, have been shown to decay by beta decay. The decay characteristics of 67Kr are in disagreement with established models and might be a hint for a different decay mode. The talk will quickly review the experimental status and present in more detail the new results. Future studies of new 2p emitters will also be discussed.
5:15 PM First Spectroscopy in 40Mg - Heather Crawford (Lawrence Berkeley National Laboratory)
First Spectroscopy in 40Mg
- Heather Crawford (Lawrence Berkeley National Laboratory)
5:15 PM - 5:35 PM
Room: Plenary-Longs Peak 40Mg, with 12 protons and 28 neutrons, lies at the edge of the neutron drip-line and at the intersection of two established regions of nuclear deformation. It is the heaviest Mg isotope experimental accessible today. With the observed collapse of the N=28 neutron shell closure below 48Ca, 40Mg is expected to have a large static prolate deformation, and extends the “peninsula” of deformation reaching from N=20 to 28 in the Mg isotopes. In addition, valence neutrons are expected to occupy the low-l 1p3/2 state, and it is possible that the picture of 40Mg could be one of a well-deformed core surrounded by a neutron halo. With the convergence of effects relating to collective nuclear motion, single-particle effects, and potentially weak-binding, the structure of 40Mg provides a rare and important benchmark for nuclear theories extending to the dripline. I will present first spectroscopic results for 40Mg, populated following one proton knockout from a secondary radioactive ion beam of 41Al at RIBF, and using the DALI2 gamma-ray detector.
5:35 PM Exotic Neutron-rich Medium-mass Nuclei with Realistic Nuclear Force - Naofumi Tsunoda (Center for Nuclear Study, the University of Tokyo)
Exotic Neutron-rich Medium-mass Nuclei with Realistic Nuclear Force
- Naofumi Tsunoda (Center for Nuclear Study, the University of Tokyo)
5:35 PM - 5:55 PM
Room: Plenary-Longs Peak The nuclear shell model provides a successful and unified description of both stable and unstable nuclei. Especially for the unstable nuclei, experimental information is less abundant than for stable ones, theoretical challenges play an ever increasing role. In this work, we will first report on the physics in so-called “island of inversion” with the model space of the sd+pf shell, and then move to the description of the shell structure of N=28,32,34 and 40 with the model space of pf+sdg shell. In both cases, it is crucial that the newly developed extended Kuo-Krenciglowa (EKK) theory of effective nucleon-nucleon interaction enables us to derive an interaction suitable for several major shells (sd + pf or pf + sdg in this case), unlike conventional Kuo-Krenciglowa (KK) theory. In the first half of this talk, we will present such an application to the island of inversion, including the cases where conventional approaches with fitted interactions encounter difficulties. By using such an effective interaction obtained from the Entem-Machleidt QCD-based χN3LO interaction and the Fujita-Miyazawa three-body force, the energies, E2 properties, and spectroscopic factors of low-lying states of neutron-rich Ne, Mg, and Si isotopes are nicely described, as the first shell-model description of the “island of inversion” without fit of the interaction. The long-standing question as to how particle-hole excitations occur across the sd-pf magic gap is clarified with distinct differences from the conventional approaches. The shell evolution is shown to appear similarly to earlier studies. In the second half, we need to incorporate the effective interaction for pf + sdg shell at least, to describe N=28,32,34 and 40 magic numbers in a unified manner. Starting from a fundamental nuclear force has a great advantage in this case, because too few experimental data are available to fit two-body matrix elements in such a large model space. We will present results of a large-scale calculation on Ca, Ti, Cr, Fe and Ni isotopes with a wide range of neutron number.
Tuesday, May 30, 2017
9:00 AM Recent Highlights From the Shores of the Island of Stability - Julia Even (KVI-CART, University of Groningen)
Recent Highlights From the Shores of the Island of Stability
- Julia Even (KVI-CART, University of Groningen)
9:00 AM - 9:25 AM
Room: Plenary-Longs Peak The hunt for heavy element reached so far proton number 118. In 2016, the IUPAC/IUPAP Joined Working Party validated the discovery of the elements with the proton number 113,115, 117, and 118. Thus, these elements were named and received their place in the periodic table. Besides the search for new elements, the studies of the basic properties of the heaviest elements are of interest for nuclear physics, atomic physic and chemistry. New and improved experimental techniques provided excess to these properties. I will give an overview on the latest research highlights and a personal view on the future of the research field of the heaviest elements.
9:25 AM Laser Spectroscopy of the Heaviest Elements - Mustapha Laatiaoui (KU Leuven)
Laser Spectroscopy of the Heaviest Elements
- Mustapha Laatiaoui (KU Leuven)
9:25 AM - 9:50 AM
Room: Plenary-Longs Peak The study of the hyperfine structure and the isotope shifts of spectral lines enables properties of atomic nuclei to be obtained in a comprehensive and nuclear model-independent way. These properties include the spin, magnetic dipole and electric quadrupole moments, and changes in the mean-square charge radii. Hence, the establishment of such optical studies in the region of deformed nuclei around nobelium-254 would inevitably attract a high level of interest of both, nuclear physics and atomic physics communities. For atomic physics, for instance, already the observation of atomic transitions in these very heavy elements would provide a stringent test of atomic theories and models addressing relativistic and quantum electrodynamic effects. These studies, however, stagnated for many years at the element fermium for which weighable samples can still be obtained. Elements beyond fermium are challenging in this respect as they are solely produced in nuclear fusion reactions, best at rates of a few atoms per second when utilizing powerful particle accelerators. Only recently successful laser spectroscopy of nobelium in single atom-at-a-time quantities was reported [M. Laatiaoui et al., Nature, 538 (2016) 495]. Several atomic transitions in nobelium-254 were observed and characterized for the first time, providing valuable data and a powerful benchmark for atomic modelling. To this end, the so-called RAdiation Detected Resonance Ionization Spectroscopy (RADRIS) technique was employed. The fusion products of interest were separated from the primary beam and thermalized in a buffer-gas stopping cell. Those remaining in a positive charged state were accumulated on a catcher filament. Then, the accumulated atoms were evaporated from the filament, ionized in a two-step photoionization process by pulsed lasers and finally guided by suitable electric fields to a silicon detector where they were unambiguously identified via their unique radioactive decay fingerprint. The investigations were extended to the isotopes nobelium-253 and nobelium-252, which were produced at even lower rates than nobelium-254. Moreover, first steps towards laser spectroscopy of lawrencium-255 were initiated. In my talk, I will highlight the recent findings and give prospects for high-precision measurements using the in-jet laser ionization spectroscopy [R. Ferrer et al., accepted to Nat. Commun.] capable of resolving nuclear isomerism in atomic spectra of these heaviest radionuclides.
9:50 AM Superheavy Element Studies at LBNL - Jacklyn Gates (Lawrence Berkeley National Lab)
Superheavy Element Studies at LBNL
- Jacklyn Gates (Lawrence Berkeley National Lab)
9:50 AM - 10:15 AM
Room: Plenary-Longs Peak Despite knowing about SHE for more than a decade, several important questions about these nuclei remain unanswered, including what are the atomic numbers, Z, and masses of these nuclei. Recently, our group has been working towards answering this intriguing question through one of three methods: (i) linking the SHE to known nuclides (ii) Z identification through observation of characteristic x-rays (iii) mass determination through mass analysis. This talk will review the progress that has been made for each of the three methods at LBNL and discuss possible avenues for the future. * This work was supported by the U.S. Department of Energy, Office of Science, Nuclear Physics, Low Energy Physics Program, through the Lawrence Berkeley National Laboratory under Contract No. DE-AC02-05CH11231
10:15 AM Influence of Fission on the Prospects for Discovering the Next New Element - Charles Folden (Texas A&M University)
Influence of Fission on the Prospects for Discovering the Next New Element
- Charles Folden (Texas A&M University)
10:15 AM - 10:40 AM
Room: Plenary-Longs Peak The four elements that were officially named most recently were all discovered in so-called “warm fusion” reactions, where compound nuclei with excitation energies of ~40 MeV are produced. The key to these experiments has been the use of neutron-rich 48Ca projectiles, which produce nearly spherical compound nuclei when reacting with actinide targets. The relatively neutron-rich compound nuclei have relatively low neutron binding energies and relatively high probabilities of survival against fission. However, more recent experiments to produce new elements using heavier projectiles have not been successful. The cross sections for all of these reactions are extremely small, so recent work at Texas A&M University has studied the reactions of similar projectiles with lanthanide rather than actinide targets. Systematic variation of the projectile and target have allowed for variation of the capture cross section as well as the difference in neutron binging energy and fission barrier height. Excitation functions for the xn and pxn exit channels of a large number of projectile/target combinations have been measured using the MARS spectrometer. A simple theoretical model has been developed that allows for the estimation of the fission and particle emission probabilities from the compound nuclei. It adequately describes the cross sections of 48Ca-induced reactions using only the fission and neutron emission widths, but describing the cross sections of reactions induced by 44Ca and 45Sc projectiles requires the inclusion of the proton and alpha emission widths. Collective effects have been found to be significant, and are needed for accurate description of the cross sections. These results suggest that the discovery of new elements will largely be controlled by the ability of the compound nucleus to survive against fission. This talk will summarize the previous work, the most recent results using 40Ar and 44Ca projectiles, and the theoretical model. Additional remarks will be made on the prospect of using radioactive beams for heavy element synthesis.
10:40 AM Coffee Break
Coffee Break
10:40 AM - 11:00 AM
Room: Shanavo & Torreys Peak Rooms
11:00 AM Nuclear Structure Studies far from Stability with Gamma-ray Spectroscopy - Silvia M. Lenzi (University of Padova and INFN, Padova, Italy)
Nuclear Structure Studies far from Stability with Gamma-ray Spectroscopy
- Silvia M. Lenzi (University of Padova and INFN, Padova, Italy)
11:00 AM - 11:25 AM
Room: Plenary-Longs Peak Far from the valley of beta stability, the nuclear shell structure undergoes important and substantial modifications. In medium-light nuclei, interesting changes have been observed such as the appearance of new magic numbers, and the development of new regions of deformation around nucleon numbers that are magic near stability. The observed changes help to shed light on specific terms of the effective nucleon-nucleon interaction and to improve our knowledge of the nuclear structure evolution towards the drip lines. In the last years, particular effort has been put from both the experimental and theoretical sides on the study of neutron-rich nuclei where these effects manifest more dramatically and their evolution can be followed along the isotopic and isotonic chains. Very interesting results have been obtained in proton-rich nuclei and in particular along the N=Z line. The most precise tool to study the excited nuclear states and their decay properties is high-resolution gamma-ray spectroscopy. Detailed nuclear structure information is becoming available with stable and radioactive beams by means of large gamma-ray spectrometers coupled to key complementary instrumentation that increases the selective power. A review of the recent experimental findings will be presented together with their theoretical interpretation.
11:25 AM Extending the Reach of ab Initio Nuclear Theory - Ragnar Stroberg (TRIUMF)
Extending the Reach of ab Initio Nuclear Theory
- Ragnar Stroberg (TRIUMF)
11:25 AM - 11:50 AM
Room: Plenary-Longs Peak A major goal of modern nuclear structure theory is to produce calculations with meaningful uncertainty estimates. Achieving this goal requires ab initio many-body methods which can employ realistic nuclear interactions and solve the Schrodinger equation with reliable precision. The past decade has witnessed a tremendous growth in the range of applicability of ab initio many-body methods, first in light nuclei, then to medium-mass closed shells, one or two particles or holes on top of closed-shells, and ground states of even-even nuclei. I will discuss recent developments in the valence-space in-medium similarity renormalization group method, which enable ab initio treatment of ground and excited states of essentially all nuclei up to mass number A~100.
11:50 AM Proton and neutron-rich systems at and beyond the drip lines - from GSI to FAIR - Haik SIMON (GSI Helmholtzzentrum für Schwerionenforschung GmbH (GSI), Darmstadt, Germany)
Proton and neutron-rich systems at and beyond the drip lines - from GSI to FAIR
- Haik SIMON (GSI Helmholtzzentrum für Schwerionenforschung GmbH (GSI), Darmstadt, Germany)
11:50 AM - 12:15 PM
Room: Plenary-Longs Peak In my presentation, I’d like to address experiments using unbound nuclei very far from the valley of stable nuclei, and exploring their extreme properties. The availability of intense secondary beams in conjunction with efficient detection setups allows for a production and study of the most extreme nuclear systems in terms of asymmetry of proton and neutron number in the continuum. Nuclei close to the drip-lines, exhibiting exotic properties themselves, are used as seeds for a subsequent production process in knockout reactions at relativistic energies. These nuclear systems challenge nuclear structure theory being open quantum systems far from the valley of beta stability as well as reaction theory while trying to describe their production mechanisms. The analysis of all particles in a kinematically overdetermined setup lead to the observation of energy and angular correlations as well as particular correlations within the different observables. The link to intrinsic properties of the unbound systems has to be explored by comparing properties of seed nuclei and to the experimental findings in the continuum. In my talk I will exemplify the above-mentioned methods, and present selected data on light systems from exotic Helium to Neon isotopes and show particular developments on the way to the upcoming FAIR facility.
12:15 PM Gamow-Teller Giant Resonances in 132Sn - Masaki Sasano (RIKEN Nishina Center)
Gamow-Teller Giant Resonances in 132Sn
- Masaki Sasano (RIKEN Nishina Center)
12:15 PM - 12:40 PM
Room: Plenary-Longs Peak The Gamow-Teller (GT) transition is one of the most basic excitation modes in nuclei, exhibiting a strong and highly repulsive collectivity as the so-called GT giant resonance (GTGR). The study of the GTGR is an essential step to elucidate the nuclear interactions and structures underlying the collectivity as well as to construct the nuclear models that can reliably describe phennomena whose behaviours are governed by nuclear spin-isospin responses such as weak-interaciton processes in astrophysical sites and double beta decay nuclei. Despite of these importances of the GTGR, the existing data are only limited to stable nuclei and there have been no data in nuclei far from the stablitity line. In this talk, the first experimetnal determination of the GT transition stregths from 132Sn to 132Sb, performed using the (p,n) reaction at RIKEN RIBF, will be presented with answers on the questions such as "the spin-isospin collectivity can be different, if one goes far from the stability line?", "most sophisticated nuclear models could reproduce the data". The speaker will also give an overview of the GT studies on nuclei that will be emergning at RIKEN RIBF in the near future.
12:40 PM Lunch Break
Lunch Break
12:40 PM - 1:45 PM
1:45 PM Tuesday Before PM Coffee
Tuesday Before PM Coffee
1:45 PM - 3:45 PM
Contributions

1:45 PM Shape Coexistence in Gold, Mercury and Bismuth Isotopes Studied by In-source Laser Spectroscopy at RILIS-ISOLDE - Andrei Andreyev (Physics Department, University of York)

2:00 PM Charge radii of neutron-deficient 52,53Fe produced by projectile fragmentation - Kei Minamisono (NSCL/MSU)

2:15 PM Results of the First Physics Experiment with 132Xe and 208Pb Targets at the SCRIT Facility - Akitomo Enokizono (Rikkyo University)

2:30 PM About Possible Ambiguities From Alpha Spectroscopy and Direct Mass Measurements of Neutron-deficient Actinium and Radium Isotopes - Marco Rosenbusch (RIKEN Nishina Center for Accelerator-Based Science)

2:45 PM Determining Quasifission Time-scales in Superheavy Element Formation Reactions - David Hinde (Australian National University)

3:00 PM First Direct Mass Measurements on Mendelevium with an MRTOF Mass Spectrograph - Yuta Ito (RIKEN Nishina Center)

3:15 PM Experiments Synthesizing Super-heavy Fl and Og Isotopes with Target Materials From ORNL Irradiated at JINR, Dubna - Nathan Brewer (JINPA/ORNL/UTK)

3:30 PM The New Isotopes 240Es and 236Bk - Joonas Konki (University of Jyväskylä)
Tuesday Before PM Coffee
Tuesday Before PM Coffee
1:45 PM - 3:45 PM
Contributions

1:45 PM Understanding the Nature of the Low-energy Enhancement in the Photon Strength Function of 56Fe - Jones Michael (LBNL)

2:00 PM Ba-ion Extraction From High Pressure Xe Gas for Double-beta Decay Studies with nEXO - Thomas Brunner (McGill and TRIUMF)

2:15 PM Charged-particle Spectroscopy with the Optical TPC - Marek Pfutzner (University of Warsaw)

2:30 PM Excursion Far Beyond the Proton Dripline Along Ar and Cl Isotopes - Ivan Mukha (Helmholzzentrum GSI)

2:45 PM Study of ⁶⁸Co Low-energy Structure via β Decay - B.P. Crider (NSCL / MSU)

3:00 PM Shape Coexistence in the 78Ni Region: Intruder Second 0+ State in 80Ge - Andrea Gottardo (Institut de Physique Nucléaire d'Orsay - IPN / LPSC Grenoble)

3:15 PM Search for the Neutron Dripline for Fluorine and Neon Isotopes - Toshiyuki Kubo (FRIB/NSCL, Michigan State University)

3:30 PM The AME2016 Atomic Mass Evaluation - Meng Wang (Institute of Modern Physics, Chinese Academy of Sciences)
3:45 PM Coffee Break
Coffee Break
3:45 PM - 4:05 PM
Room: Shavano
4:05 PM Tuesday After PM Coffee
Tuesday After PM Coffee
4:05 PM - 6:20 PM
Contributions

4:05 PM Monopole and Dipole Transitions in Light Nuclei - Yoshiko Kanada-En'yo (Department of Physics, Kyoto University)

4:20 PM A Hybrid Configuration Mixing Model for the Low-lying States of Unstable Nuclei - Gianluca Colò (University of Milano and INFN)

4:35 PM Quantifying Uncertainties for Optical Model Parameters and Cross Sections - Amy Lovell (MSU/NSCL)

4:50 PM Time-dependent Description Nuclear Collisions and Infinite Nucleonic Systems - Bastian Schuetrumpf (NSCL / Michigan State University)

5:05 PM Challenges in Describing Near-Barrier Fusion: Pinning Down the Interplay of Breakup, Transfer and Fusion - M. Dasgupta (Australian National University)

5:20 PM Mass Measurements of Neutron-rich Rare-earth Isotopes - Rodney Orford (McGill University)

5:35 PM Precision Mass Measurements of Neutron-rich In Isotopes Relevant to r-process Calculations - Carla Babcock (TRIUMF)

5:50 PM Informing Neutron Capture on Tin Isotopes in r-process Freeze Out - Jolie Cizewski (Rutgers University)

6:05 PM Measurement of 21Na(α,p)24Mg Cross Section for the Study of 44Ti Production in Supernovae - Alison Laird (University of York)
Tuesday After PM Coffee
Tuesday After PM Coffee
4:05 PM - 6:20 PM
Contributions

4:05 PM Shape Evolution in Neutron-rich Kr Isotopes Beyond N=60: First Spectroscopy of 98,100Kr - Freddy Flavigny (IPN Orsay)

4:20 PM Collectivity in the Vicinity of 78Ni: Coulomb Excitation of Neutron-rich Zn at HIE-ISOLDE - Piet Van Duppen (KU Leuven - IKS)

4:35 PM Shape Coexistence in Neutron-rich Odd-mass S Isotopes - Tea Mijatovic (NSCL)

4:50 PM Collectivity Along N=50: The Neutron-magic 92Mo and 94Ru - Rosa María Pérez Vidal (Instituto de Física Corpuscular, CSIC-Universitat de València)

5:05 PM Gamma-spectroscopy of Neutron-rich $^{79}$Cu Through Proton Knockout - Louis Olivier (IPN Orsay)

5:20 PM Transition Strengths in 22,23Mg as Tests of ab Initio Theory - Jack Henderson (TRIUMF)

5:35 PM Shape Isomerism in 66Ni - Silvia Leoni (Università di Milano and INFN sez. Milano)

5:50 PM E0 Transitions and Shape Coexistence in 54,56,58Fe - Tibor Kibedi (Department of Nuclear Physics, RSPEE, The Australian National University)

6:05 PM The Nature of 0+ Sates in Deformed Nuclei - Ani Aprahamian (University of Notre Dame)
Wednesday, May 31, 2017
9:00 AM Electromagnetic Response in Nuclei: From Few- to Many-body Systems - Sonia Bacca (TRIUMF)
Electromagnetic Response in Nuclei: From Few- to Many-body Systems
- Sonia Bacca (TRIUMF)
9:00 AM - 9:25 AM
Room: Plenary-Longs Peak The electromagnetic response of nuclei is a fundamental quantity to calculate, since due to its perturbative nature a clean comparison with experimental data can be performed. First priciples computations are key to bridge nuclear physics with the underlying QCD regime [1]. Nowadays this valuable information is not only accessible for the lightest nuclei, but novel theoretical approaches are being developed to tackle nuclei with a larger number of nucleons. Combining the Lorentz integral transform with the coupled-cluster method recently allowed us to perform ab initio calculations of response functions and related sum rules for light and medium-mass nuclei [2,3]. I will present recent highlights on neutron skins and polarizabilities and discussed them in the context of recent and future experiments [4,5]. References: [1] S. Bacca and S. Pastore, J. Phys. G: Nucl. Part. Phys. 41 123002 (2014). [2] S.Bacca et al., Phys. Rev. Lett. 111m 122502 (2013). [3] M.Miorelli et al., Phys. Rev. C 94, 034317 (2016). [4] G. Hagen et al., Nature Physics 12, 186-190 (2016). [5] J. Birkhan et al., arXiv:1611.07072.
9:25 AM Nuclear Forces for ab Initio Nuclear Theory - Christian Forssén (Chalmers University of Technology)
Nuclear Forces for ab Initio Nuclear Theory
- Christian Forssén (Chalmers University of Technology)
9:25 AM - 9:50 AM
Room: Plenary-Longs Peak Predictive power requires the ability to quantify theoretical uncertainties. While it is true that theoretical error estimates are difficult to obtain, the pursuit thereof plays a pivotal role in science. Reliable theoretical errors can help to determine to what extent a disagreement between experiment and theory hints at new physics, and they can provide input to identify the most relevant new experiments. In this talk I will show that nuclear theory is at a stage where such questions can be addressed. Chiral effective field theory can be used to systematically bridge the gap from low-energy quantum chromodynamics to nucleons and pions as effective nuclear-physics degrees of freedom. Following this avenue we have made the quantification of theoretical uncertainties possible through the incorporation of state-of-the-art statistical and computational tools. In particular, we employ two different approaches to determine the coupling constants of chiral nuclear interactions: (1) The simultaneous optimization of nucleon-nucleon, pion-nucleon and few-nucleon data, and (2) In-medium optimization for which binding energies and radii of selected isotopes of carbon and oxygen are also used as input data. I will present results from both of these different approaches that together provide important steps towards our understanding of nuclear forces.
9:50 AM Where is the Neutron Drip-line for Oxygen? - Kevin Fossez (NSCL/MSU)
Where is the Neutron Drip-line for Oxygen?
- Kevin Fossez (NSCL/MSU)
9:50 AM - 10:15 AM
Room: Plenary-Longs Peak The presence of neutron and proton shell closures in the nucleus $^{28}$O, together with strong continuum coupling effects, make neutron-rich oxygen isotopes a unique laboratory for testing nuclear models. In this work, we investigate neutron-rich oxygen isotopes using the Gamow Shell Model and the Density Matrix Renormalization Group method with an effective finite-range two-body interaction optimized to the bound states and resonances of $^{23-26}$O assuming a core of $^{22}$O. Our results suggest the existence of narrow excited states in $^{25}$O and $^{27}$O decaying by neutron and gamma emission, and a near-threshold ground-state for $^{28}$O.
10:15 AM Ab Initio Studies of Nucleonic Matter - Arianna Carbone (TU Darmstadt)
Ab Initio Studies of Nucleonic Matter
- Arianna Carbone (TU Darmstadt)
10:15 AM - 10:40 AM
Room: Plenary-Longs Peak Nucleonic matter has important implications on many branches of nuclear science: from the bulk properties of exotic nuclei to the equation of state of neutron star matter. After we have extended the self-consistent Green’s function (SCGF) theory to account for three-nucleon forces, it is now possible to make reliable predictions of nucleonic matter at both zero and finite temperatures and with full chiral interactions, a task that was not possible until a few years a ago. The talk will present the SCGF approach as a very convenient way to investigate microscopic and thermodynamical properties of nucleonic matter. Among recent results, the prediction of the liquid-gas phase transition critical temperature in symmetric matter appears to be in reasonable agreement with experimental outcomes. Also studies of both saturation properties and finite temperature behaviors in infinite matter are pointing towards the necessity to refine the fitting procedure of low-energy constants. Moreover, I will show how first-principle tests of thermal approximations used in equations of state to study stellar environments questions the validity of such simulations.
10:40 AM Coffee Break
Coffee Break
10:40 AM - 11:05 AM
Room: Shavano
11:05 AM The Difference a Few Neutrons Makes in the Fusion of Light Nuclei: Structure and Dynamics - Romualdo Desouza (Indiana university)
The Difference a Few Neutrons Makes in the Fusion of Light Nuclei: Structure and Dynamics
- Romualdo Desouza (Indiana university)
11:05 AM - 11:30 AM
Room: Plenary-Longs Peak Fusion of neutron-rich light nuclei at near barrier energies involves the interplay of both structure and dynamics. Examination of fusion for an isotopic chain of nuclei provides a means to access the low density tail of the neutron density distribution and the polarizability of nuclear matter. Development of a new technique that allows measurement of the fusion cross-section at near barrier energies will be presented. The direct measurement of fusion residues with this technique is used to extract the fusion cross-section. The measured fusion excitation functions for 18,19O + 12C and 39,47K + 28Si will be shown and the observed fusion enhancement will be compared with theoretical model predictions.
11:30 AM How Does Breakup of Light Weakly-bound Projectiles Affect Fusion? - Edward Simpson (Australian National University)
How Does Breakup of Light Weakly-bound Projectiles Affect Fusion?
- Edward Simpson (Australian National University)
11:30 AM - 11:55 AM
Room: Plenary-Longs Peak Fusion reactions provide the means to discover new elements, produce new exotic isotopes, investigate nuclear structure, and study many-body quantum dynamics. The fusion of light, weakly-bound projectiles (e.g., 6,7Li, 9Be) with heavy targets at above-barrier energies is found to be suppressed by 25-35% compared to both model expectations, and to fusion of strongly-bound projectiles [1]. This presents a major challenge to our understanding of fusion, particularly for measurements with nuclei far from stability. Due to their low breakup thresholds, direct breakup of these nuclei into their intrinsic clusters (6Li→αd, 7Li→αt, 9Be→ααn) may prevent fusion – after breakup, capture of the complete charge of the projectile is be hindered. Although these direct breakup modes are present, many unbound states are also accessible via nucleon transfer [2]. For example, 7Li can disintegrate through proton pickup, forming unbound 8Be. This mode becomes dominant as the target mass decreases, with direct breakup negligible for A<60 [3]. To infer the influence of breakup on fusion we need to understand both the mechanisms causing breakup and their timescales. Narrow resonances such as the 8Be 0+ (τ≈10−16 s) survive much longer than the collision time (10−21 s), and will arrive at the fusion barrier intact. Thus they are not expected to contribute to fusion suppression. Only if breakup occurs on the timescale of the collision (e.g. via the short-lived 8Be 2+ state) can fusion be suppressed. Here we discuss recent measurements of sub-barrier breakup and their interpretation in terms of a classical dynamical model [4]. In the absence of a quantum model for transfer triggered breakup, classical trajectory models were developed, guided by experimental insights, to understand breakup and incomplete fusion in near-barrier collisions. Comparison with experimental measurements have shown how the correlations of the breakup fragments are altered by their proximity to the target nucleus at breakup [5] providing a probe of breakup timescales. These results suggest that the detailed structure of the intermediate states populated is crucial in determining the influence of breakup on fusion. References: [1] L. F. Canto et al., Phys. Rep. 596, 1 (2015) (and refs. therin) [2] D. H. Luong et al., PLB 695, 105 (2011) [3] S. Kalkal et al., PRC 93, 044605 (2016) [4] A. Diaz-Torres et al., PRL 98, 152701 (2007) [5] E. C. Simpson et al., PRC 93, 024605 (2016)
11:55 AM Progress in Fission Investigated in Complete Kinematic Measurements - Jose Benlliure (Universidade de Santiago de Compostela)
Progress in Fission Investigated in Complete Kinematic Measurements
- Jose Benlliure (Universidade de Santiago de Compostela)
11:55 AM - 12:20 PM
Room: Plenary-Longs Peak The observation of asymmetric fission in 1948 was one of the main discoveries promoting the nuclear shell model. However, more than 75 years after its discovery fission still represents a challenge for nuclear physicists. In particular, the stabilization of the heavy fission fragment around A~140 initially explained in terms of the double shell closure around Z=50 and N=82 or N~88 was questioned by K.H. Schmidt and collaborators ten years ago. More recently, asymmetric fission partitions around 180Hg were observed by A. Andreyev and collaborators and interpreted by P. Moller without any shell effects. Concerning the dynamics of fission the situation is not better. Pre- and post-scission particle emission and fission probabilities indicate that simple statistical approaches are not valid and models describing the dynamics of the process are required. Because of the complexity of time-dependent microscopic approaches, models based on transport equations (e.g. Fokker-Planck or Langevin) including dissipative and stochastic terms where the main ingredients are the potential landscape and the friction and inertia tensors are used. The friction or viscosity parameter is particularly interesting since it quantifies the magnitude of the coupling between collective and intrinsic degrees of freedom in fission. The complete isotopic and kinematic identification of both fission fragments recently achieved using coulex induced fission in inverse kinematics should represent a real breakthrough in the investigation of fission providing answers to many of the open questions. In the near future this experimental progress could even improve taking advantage of quasi-free nucleon scattering inducing fission, e.g. (p,2pf).
12:20 PM Microscopic Theory of Nuclear Fission - Nicolas Schunck (Lawrence Livermore National Laboratory)
Microscopic Theory of Nuclear Fission
- Nicolas Schunck (Lawrence Livermore National Laboratory)
12:20 PM - 12:45 PM
Room: Plenary-Longs Peak Since its discovery in the late nineteen thirties, nuclear fission has remained one of the most complex and elusive problems in physics and gaps in our understanding of this phenomena can impact progress in other areas. For example, in basic science accurate knowledge of spontaneous fission half-lives is key to predicting the stability of superheavy elements, and fission fragment charge and mass distributions are also important ingredients in simulations of the formation of elements in nuclear capture processes (fission recycling). In applications of nuclear science for energy production, fuel cycle optimization is also strongly dependent on the characteristics of the fission process in actinides. In all these examples, measurements are either difficult, for technological, financial or safety reasons, or simply impossible. Therefore, most information comes from theoretical predictions. These predictions are often based on powerful semi-phenomenological models that have been developed several decades ago and have been finely tuned on existing data, which limits their predictive power. In an ideal world, a predictive theory of fission should instead be based solely on quantum many-body methods and our best knowledge of nuclear forces. Today, there is a consensus that the nuclear energy density functional theory (DFT) is currently the best framework to achieve a microscopic description of fission. Unfortunately, the proper implementation of nuclear DFT comes at a tremendous computational cost, which explains why progress had been relatively slow in the past. The recent development of leadership computing facilities in the USA, Europe and Asia has, however, introduced a paradigm shift: Calculations that were simply unfeasible only 5 or 10 years ago can now be completed in just a few hours. Such a massive increase in computing power has opened entirely new perspectives and triggered a spectacular renaissance of fission studies. After a historical introduction to fission theory and models, I will give an overview of the DFT approach to nuclear fission and highlight a few selected results.
7:00 PM Don’t be Such a Scientist: The Intersection of Science, Communication and Policy
Don’t be Such a Scientist: The Intersection of Science, Communication and Policy
7:00 PM - 8:00 PM
For most of our professional lives, we perform fundamental research with a goal towards solving problems that advance scientific knowledge. Such a career requires significant investment in education, skill in analytical thinking and problem solving, and usually some sort of sustained federal funding of instrumentation and personnel. Although the costs associated with basic research are small compared to other federal expenditures, in the current funding era we are increasingly asked to justify the taxpayer investment in scientific research. Simultaneously, we wish to continue to attract the best students into our field. Both the persuasion of people to support a pro-science policy and the attraction of new people into a STEM career require better communication skills than most of us have ever developed. In Randy Olsen’s book: “Don’t be Such a Scientist”, he argues that we have done such a poor job communicating science that we are lucky it continues in the US at all! The evolution of one particular scientific career from basic nuclear science into one with an applied environmental science direction using nuclear science techniques will be presented. This includes using ion beam analysis to study lake sediments, and to trace flame retardants from consumer products into our environment. Recent studies focus on an emerging class of chemicals of concern (Per- and Polyfluorinated Alkyl Substances) that are ubiquitous in in our textiles, food packaging, personal care products and industrial uses. But the most significant of these findings required improved communication skills in order to achieve any significant effect on science policy. Therefore, it could be argued that more of us should develop the type of communication skills necessary to alter the science policy landscape in the US.
Thursday, June 1, 2017
9:00 AM Nuclear Structure Studies by Measurements of Nuclear Spins, Moments and Charge Radii Via Collinear Laser Spectroscopy at ISOLDE - Gerda Neyens (KU Leuven)
Nuclear Structure Studies by Measurements of Nuclear Spins, Moments and Charge Radii Via Collinear Laser Spectroscopy at ISOLDE
- Gerda Neyens (KU Leuven)
9:00 AM - 9:25 AM
Room: Plenary-Longs Peak High-resolution laser spectroscopy at ISOLDE gives access to properties of nuclear ground states and long-lived (> 5ms) isomeric states of radioactive nuclei far from stability, such as nuclear spins, nuclear magnetic and quadruple moments and charge radii [1]. These fundamental properties of exotic nuclei provide important information for the investigation of the nuclear structure in different regions of nuclear chart. Currently, two complementary collinear laser spectroscopy set-ups are available at ISOLDE: one for optically detected Collinear Laser Spectroscopy (COLLAPS) [2] and one for Collinear Resonant Ionization Spectroscopy (CRIS) [3]. By combining these two techniques, the nuclear structure in several key regions of the nuclear chart is been studied, from the very neutron-deficient to the very neutron-rich side of the nuclear landscape. Recent results from studies in the Ca and Ni regions will be presented and an outlook to future opportunities will be presented. References: [1] P. Campbell et al., Progress in Particle and Nuclear Physics 86, 127 (2016). [2] http://collaps.web.cern.ch/ [3] http://isolde-cris.web.cern.ch/isolde-cris/
9:25 AM Manifestation of Three-nucleon Spin-orbit Interaction in Nuclear Charge Radii - Hitoshi Nakada (Chiba University)
Manifestation of Three-nucleon Spin-orbit Interaction in Nuclear Charge Radii
- Hitoshi Nakada (Chiba University)
9:25 AM - 9:50 AM
Room: Plenary-Longs Peak The nuclear charge radii have supplied high-precision and model-independent data on nuclear structure. In particular, thanks to the collaboration of atomic physics, difference of the charge radii among isotopes, i.e. isotope shifts (field shifts, to be more precise), have been measured with striking precision. The isotope shifts have been known to be a good indicator for variation of nuclear structure along an isotopic chain. They may also provide information of the nucleonic interaction. The isotope shifts in the Pb nuclei was suggested to be relevant to the isospin content of the nucleonic LS interaction two decades ago. However, fictitious degeneracy or level inversion had to be introduced to reproduce the observed kink in the isotope shifts of the Pb nuclei. Via a self-consistent mean-field (SCMF) study, I point out that the three-nucleon (3N) interaction, which has been indicated by the chiral effective field theory (EFT) and pointed out to narrow the gap between the theoretical description and experiments of the ls splitting, may also solve the problem of the isotope shifts. The kink in Pb is described fairly well with a reasonable single-particle-level difference between the relevant orbitals. It is found that the close charge radii between 40Ca and 48Ca, which is another long-standing problem, are well reproduced as well. As the SCMF calculations clarify physics mechanism how the 3N LS interaction influences the nuclear charge radii, these data can be regarded as a manifestation for the 3N LS interaction. It is suggested that kinks as observed in Pb can be universal at the neutron magicity in the isotopes with magic proton numbers. As an example, a kink is predicted in the isotope shifts of Sn at N=82, which will be a touchstone of this picture linking the nuclear radii and the 3N LS interaction.
9:50 AM The Use of Storage Rings in the Study of Reactions at Low Momentum Transfers - Nasser Kalantar-Nayestanaki (KVI-CART/Univ. of Groningen)
The Use of Storage Rings in the Study of Reactions at Low Momentum Transfers
- Nasser Kalantar-Nayestanaki (KVI-CART/Univ. of Groningen)
9:50 AM - 10:15 AM
Room: Plenary-Longs Peak Several nuclear reactions are best investigated when the momentum transfer to the nucleus is small. Among these are the IsoScalar Giant Monopole Resonance (ISGMR) which helps determine one of the parameters of the equation of state, namely the incompressibility of nuclear matter, and proton elastic scattering from nuclei which is sensitive to parameters of nuclear density such as the matter root-mean-square radius. These have been extensively studied in the past using stable beams. However, with the advent of radioactive ion facilities around the world, it is desirable to study these reactions with unstable nuclei. The reactions, however, have to take place in inverse kinematics in which the radioactive ions impinge on a light target (hydrogen or helium). Simple kinematics calculations show that the outgoing recoil particles possess extremely low energies (down to few hundred keVs). External targets are, therefore, not suitable for these reactions. There are two alternative methods to deal with this challenge: either do the experiments in storage rings with gas jet targets or any other thin targets, or perform the measurements with an active target which also acts as a detector. In both cases, the energy threshold will be much lower than a fixed target of a reasonable thickness. We have performed measurements with the radioactive 56Ni using both methods. In the ring measurements, proton elastic scattering was the main goal for this nucleus while feasibility studies were done with 58Ni and a helium target to investigate ISGMR. In this presentation, the experimental method used in the storage ring will be discussed along with some results, and a comparison will be made with the results of the active target measurements.
10:15 AM Beta-delayed Neutron Spectroscopy with VANDLE, Evidence for Gamow-Teller Decay of 78Ni Core - Robert Grzywacz (University of Tennessee)
Beta-delayed Neutron Spectroscopy with VANDLE, Evidence for Gamow-Teller Decay of 78Ni Core
- Robert Grzywacz (University of Tennessee)
10:15 AM - 10:40 AM
Room: Longs Peak The beta-delayed neutron emission of neutron-rich isotopes near 78Ni and 132Sn regions were studied using the neutron time-of-flight technique with Versatile Array of Neutron Detectors at Low Energies (VANDLE). We have measured neutron energy spectra, which showed emission from states at excitation energies high above neutron separation energy. This effect was previously not observed in the beta-decay of mid-mass nuclei. For the example cases of 83,84Ge, large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation and was interpreted as evidence for allowed beta-decay to core-excited states of 78Ni. To describe the observed features of this decay, we have developed shell model calculations in the proton fpg9/2, and neutrons extended fpg9/2+d5/2 valence space using realistic interactions. Enhanced and concentrated beta-decay strength for neutron-unbound states may be common for very neutron-rich nuclei and would lead to intense beta-delayed high-energy neutrons or multi-neutron emission probabilities that in turn will affect astrophysical nucleosynthesis models.
10:40 AM Coffee Break
Coffee Break
10:40 AM - 11:05 AM
Room: Shavano
11:05 AM Shape Coexistence in Neutron-rich Strontium Isotopes at N=60 - Emmanuel Clement (CNRS-GANIL)
Shape Coexistence in Neutron-rich Strontium Isotopes at N=60
- Emmanuel Clement (CNRS-GANIL)
11:05 AM - 11:30 AM
Room: Plenary-Longs Peak Neutron-rich A~100 nuclei are among the best examples of interplay of microscopic and macroscopic effects in nuclear matter. A dramatic onset of quadrupole deformation is observed in the neutron-rich Zr and Sr isotopes at N=60, making this region an active area of experimental and theoretical studies. This rapid shape transition is accompanied by the appearance of low-lying 0+2 states. Low-energy Coulomb excitation experiments were to study properties of coexisting structures in 96,98Sr (N=58,60) using post-accelerated exotic Sr beams from REX-ISOLDE. The experiments were carried out in the particle-gamma coincidence mode using the MINIBALL HPGe array coupled to an annular Double Sided Silicon Detector. Reduced transition probabilities and spectroscopic quadrupole moments were extracted from the measured differential Coulomb excitation cross sections. The results support the scenario of shape transition at N=60 giving rise to coexistence of two very different configurations in 96,98Sr. In 96Sr, the spectroscopic quadrupole moment of the first 2+ state was found to be small and negative, corresponding to a weak prolate deformation. In 98Sr, the large and negative spectroscopic quadrupole moments in the ground state band prove its well-deformed prolate character, while the value close to zero obtained for the 2+2 state confirms that a spherical configuration coexists with the deformed configuration of the ground state. The comparison of the B(E2) values and the spectroscopic quadrupole moments between the 2+1 state in 96Sr and the 2+2 state in 98Sr underlines their similarity and further supports the shape inversion when crossing the N=60 line. Furthermore, a very small mixing between the coexisting structures was determined from measured intra-band transition probabilities in 98Sr. This effect has been attributed to the rapidity of the shape change at N=60: a larger mixing would give rise to a more gradual transition from spherical to deformed ground state in Sr isotopes, like what is observed in other areas of shape coexistence, for example neutron-deficient Kr and Hg isotopes. The experimental results, together with a detailed comparison with new beyond-mean-field calculations, will be presented. The present work will be also highlighted in a larger framework of the shape change in the mass region.
11:30 AM Recent Developments in Shape Coexistence Studies - Wolfram KORTEN (CEA Saclay)
Recent Developments in Shape Coexistence Studies
- Wolfram KORTEN (CEA Saclay)
11:30 AM - 11:55 AM
Room: Plenary-Longs Peak The information on collective properties of nuclei far from stability has dramatically improved in recent years due to the availability of radioactive ion beams used, e.g., for Coulomb excitation studies both below the Coulomb barrier and at relativistic energies. These studies are complemented by spectroscopic studies and lifetime measurements applied to other reaction mechanisms suitable for producing exotic nuclei. Over the last few years we have carried out a research program using these complementary techniques, and applied them to several mass regions, where shape coexistence and a sudden evolution of nuclear shapes are expected. In this presentation recent results for two such mass regions will be presented, the A~70 nuclei at and beyond the N=Z line and neutron-rich nuclei in the A~100 region. In the first case the closeness and influence of the proton drip line on the shape properties is being explored, while in the second case the evolution of nuclear shapes beyond the onset of strong deformation at N=60 (in particular in Sr and Zr isotopes) as well as the importance of the triaxial degree of freedom in the Mo and Ru isotopes at N~64-70 are of strong current interest. In this presentation recent results will be presented that were obtained using several different facilities: On one hand, using stable beams from GANIL and the combination of the VAMOS and EXOGAM spectrometers, heavy-ion induced fission was used to obtain new lifetime results in several Zr, Mo, Ru and Pd isotopes. On the other hand radioactive neutron-rich beams from the CERN-ISOLDE and ANL-Caribu facilities were used to perform Coulomb excitation experiments yielding new electro-magnetic matrix elements in the same nuclei. Finally, the even more exotic proton-rich nuclei around A~70 were studied using relativistic Coulomb excitation of fragmentation beams from the RIBF facility at RIKEN.
11:55 AM First Experiment in the 100Sn Region Using HIE-ISOLDE - Joakim Cederkall (Lund University)
First Experiment in the 100Sn Region Using HIE-ISOLDE
- Joakim Cederkall (Lund University)
11:55 AM - 12:20 PM
Room: Plenary-Longs Peak In this presentation results from the first experiment with the new post-accelerator HIE-ISOLDE at CERN will be given. HIE-ISOLDE expands the possibilities offered by its predecessor, REX-ISOLDE, by increasing the final energy of the radioactive beam (RIB) to 5 MeV/u and 10 MeV/u in two steps, using a set of new superconducting cavities. The first step, to 5 MeV/u, facilitates e.g. the use of heavier targets in the the Coulomb excitation program that was started with REX-ISOLDE. In practice this means that the earlier measurements, that were largely restricted to excitation of the lowest lying states in the RIB, now can include states at higher energies, and simultaneously substantially increase the statistics for the states addressed in the REX-ISOLDE campaign. The first production run with HIE-ISOLDE was part of the program in the 100Sn region. In this case the use of the new post-accelerator means that the measurements of the transition probabilities from the ground state to the first excited 2+ state in the light even Sn isotopes, that earlier were statistics limited, now are observed with some two orders of magnitude higher statistics. In addition, multi-step excitation is observed providing further information on the yrast sequence in these isotopes. The new results will be discussed and put into the context of earlier measurements and theoretical interpretations.
12:20 PM Properties of Mg and S Isotopes in a Beyond Mean Field Theory. - J. Luis Egido (Universidad Autonoma de Madrid)
Properties of Mg and S Isotopes in a Beyond Mean Field Theory.
- J. Luis Egido (Universidad Autonoma de Madrid)
12:20 PM - 12:45 PM
Room: Plenary-Longs Peak Traditionally effective interactions like Skyrme, Gogny or relativistic interactions have been used in basic mean field approaches to describe with great success bulk properties of ground states of nuclei, such as masses, quadrupole moments, radii, etc. However, recent developments in beyond mean field calculations, with particle number and angular momentum projection in conjunction with the Generator Coordinate Method (with the deformations $(\beta,\gamma)$, pairing gaps $(\Delta_Z,\Delta_N)$ and angular frequency as generator coordinates) have shown that the Gogny force [1,2] is also able to provide high quality nuclear spectroscopy. This approach has recently been extended to odd-even nuclei [3] allowing thereby to perform isotopic (isotonic) studies of nuclear properties. The strong point of this approach is the ability to simultaneously provide a good description of bulk properties, like binding energies and multipole moments, as well as an accurate and detailed account of excitation energies and transition probabilities. As a validation of the theory in this talk we present a study of the Magnesium isotopic chain. We obtain an outstanding description of the ground-state properties, in particular binding energies, odd-even mass differences, mass radii and electromagnetic moments among others. At the same time a comprehensive study of the spectroscopic properties of $^{25}$Mg is discussed. These studies, together with the spectrum and the transition probabilities of the nuclei $^{42}$Si and $^{44}$S, show that these calculations provide an accuracy comparable with state-of-the-art shell model calculations with tuned interactions. The advantages of the present approach as compared to the shell-model one are the added value of the intrinsic system interpretation and that the interaction, the Gogny force, is well known for its predictive power and good performance for bulk properties all over the chart of nuclides. References: 1.- M. Borrajo, T. R. Rodriguez and J. L. Egido, Phys. Lett. B 746 (2015) 341-346 2.- J. L. Egido, M. Borrajo and T. R. Rodriguez, Phys. Rev. Lett. 116 (2016) 052502. 3.- M. Borrajo and J. L. Egido, Phys. Lett. B 764 (2017) 328–334
12:45 PM Lunch Break
Lunch Break
12:45 PM - 1:45 PM
1:45 PM Thursday Before PM Coffee
Thursday Before PM Coffee
1:45 PM - 3:45 PM
Contributions

1:45 PM High-resolution Laser Ionisation Spectroscopy of Heavy Elements in Supersonic Gas Jet Expansion - Rafael Ferrer (KU Leuven IKS)

2:00 PM Recent Technical Developments and New Scientific Endeavors at IGISOL - Iain Moore (University of Jyväskylä)

2:15 PM Recent Upgrades of the Penning-trap Mass Spectrometer SHIPTRAP for High-precision Mass Measurements - Francesca Giacoppo (Helmholtz-Institut Mainz and GSI Helmholtzzentrum für Schwerionenforschung GmbH)

2:30 PM New ISOLDE Setup for Laser Polarization and for Studies Using Spin-polarized Nuclei - Magdalena Kowalska (CERN)

2:45 PM Advancing Penning Trap Mass Spectrometry of Rare Isotopes at the LEBIT Facility - Ryan Ringle (NSCL)

3:00 PM BRIKEN Beta-delayed Neutron Detector Array at RIKEN* - Nathan Brewer (ORNL/UTK)

3:15 PM Recent Results From the Active Target Time Projection Chamber - Daniel Bazin (NSCL/MSU)

3:30 PM The ISOLDE Facility and the HIE-ISOLDE Project, Recent Results - Maria J G. Borge (ISOLDE-CERN)
Thursday Before PM Coffee
Thursday Before PM Coffee
1:45 PM - 3:45 PM
Contributions

1:45 PM Quantum Self-organization and Nuclear Shapes - Takaharu Otsuka (University of Tokyo)

2:00 PM Precision Mass Measurements of Nutron-rich Chromium Isotopes into the <i>N</i>=40 "Island of Inversion": From a New "ISOL" Beam to ab-initio Shell Model Calculations. - Maxime Mougeot (CNRS, Universite Paris Sud, Orsay)

2:15 PM High-sensitivity and High-resolution Laser Spectroscopy of 76,77,78Cu at CRIS - Ruben de Groote (KU Leuven)

2:30 PM Weakly Bound and Unbound Light Nuclei From ab Initio Theory - Angelo Calci (TRIUMF)

2:45 PM Recent Developments of the Gamow Shell Model for Nuclear Structure and Reaction - Nicolas Michel (NSCL/MSU)

3:00 PM Resonance and Continuum in Atomic Nuclei - Furong Xu (Peking University)

3:15 PM Recent Progress in Building Novel Nonlocal Energy Density Functionals - Jacek Dobaczewski (University of York)

3:30 PM Fusion with Exotic Nuclei Using Microscopic Methods - Cedric Simenel (Australian National University)
3:45 PM Coffee Break
Coffee Break
3:45 PM - 4:05 PM
Room: Shavano
4:05 PM Thursday After PM Coffee
Thursday After PM Coffee
4:05 PM - 6:20 PM
Contributions

4:05 PM β -delayed Neutron Emission Studies for Heavy Isotopes - Roger Caballero-Folch (TRIUMF)

4:20 PM Gamma and Fast-timing Spectroscopy Around 132Sn From the Beta-decay of In Isotopes - Jaime Benito García (Universidad Complutense de Madrid)

4:35 PM Gamow-Teller Decay of 74Co and Decay Properties of 78Co→78Ni - Shintaro Go (University of Tennessee)

4:50 PM Beta-Decay and Mass-Measurement Studies of Deformed, Neutron-Rich Nuclei in the A~160 Region* - Filip Kondev (Argonne National Laboratory)

5:05 PM Intruder States in Neutron Rich Phosphorus Isotopes Near N=28 - Vandana Tripathi (Department of Physics, Florida State University, Tallahassee Fl 32306, USA)

5:20 PM Shape Coexistence in Neutron-rich 31Mg Investigated by Beta-gamma Spectroscopy of Spin-polarized 31Na - Hiroki Nishibata (RIKEN Nishina Center)

5:35 PM Detailed Spectroscopy of Neutron-rich Sn Isotopes with GRIFFIN - Kenneth Whitmore (Simon Fraser University)

5:50 PM Decay Spectroscopy of Neutron-Rich Cd Around the \mbox{\textit{N} = 82} Shell Closure - Nikita Bernier (TRIUMF/UBC)

6:05 PM Spying on Intruders in the 68Ni Region with Fast Timing - Luis M Fraile (Universidad Complutense de Madrid)
Thursday After PM Coffee
Thursday After PM Coffee
4:05 PM - 6:20 PM
Contributions

4:05 PM Charge Exchange Reactions of Unstable Nuclei and the Beta-Decay Strength - I. Tanihata (School of Physics and Nuclear Energy Engineering and IRCNPC, Beihang University, Beijing 100191, China and RCNP, Osaka University, Ibaraki, Osaka 567-0047, Japan)

4:20 PM Structure of Unbound Nuclei 10-N and 9-He - Grigory Rogachev (Texas A&M University)

4:35 PM Probing Neutron-Proton Correlation and 3N-force in 12C - Jenny Lee (The University of Hong Kong)

4:50 PM Neutrons Correlations in the Continuum of Two (core + 4n) Systems - Aldric REVEL (GANIL)

5:05 PM Evidence for Z=6 Subshell Cclosure in Neutron-rich Carbon Isotopes - Hooi Jin ONG (RCNP, Osaka University)

5:20 PM Direct Measurements of (α,p) Reactions with ANASEN - Jon Lighthall (Louisiana State University)

5:35 PM Investigation of 198Hg and 199Hg Through Direct Reactions for the Interpretation of EDM Limits - Alejandra Diaz Varela (University of Guelph)

5:50 PM Quasi-free Proton Knockout Reactions on the Oxygen Isotopic Chain - Leyla Atar (TU Darmstadt, GSI and University of Guelph)

6:05 PM Study on the Isoscalar Excitation of the Pygmy Dipole Resonance in 68Ni - Nunzia Simona Martorana (LNS-INFN, Catania, Italy)
7:30 PM Conference Dinner
Conference Dinner
7:30 PM - 9:00 PM
Room: Grays Peak
Friday, June 2, 2017
9:00 AM Applications of β-radiation Detected NMR in Wet Chemistry, Biochemistry and Medicine - Monika Stachura (TRIUMF)
Applications of β-radiation Detected NMR in Wet Chemistry, Biochemistry and Medicine
- Monika Stachura (TRIUMF)
9:00 AM - 9:25 AM
Room: Plennary-Longs Peak Many physiological processes in nature are governed by the interaction of biomolecules with metal ions. Some biologically highly relevant metal ions, such as Mg2+, Cu+ and Zn2+, are silent in most spectroscopic techniques leaving wide gaps in understanding their biological functions. Therefore, there is the need for finding new experimental approaches to directly study these metal ions. Recently, β-radiation detected nuclear magnetic resonance (β-NMR) spectroscopy was successfully applied to liquid samples at the ISOLDE and ISAC facilities at CERN and at TRIUMF, Canada’s national laboratory for particle and nuclear physics, respectively. This marks an achievement, which opens new opportunities in the fields of wet chemistry. In contrast to earlier measurements, the resonance spectra of 31Mg+ implanted into different ionic liquid samples, recorded at ISAC, showed highly-resolved resonances originating from Mg ions occupying different coordination geometries, illustrating that β-NMR can in fact discriminate between different structures – the first and very important step towards the applications of this technique in biochemistry and medicine. Recorded resonance line widths are comparable or even narrower than the ones in conventional NMR spectroscopy on similar systems, underlining the complementarity and advantages of β-NMR. After these successful tests, a new spectrometer for bio-β-NMR experiments is currently under construction at TRIUMF’s β-NMR facility, which will allow for experiments not only on different samples, such as gels, and liquids, but also at different vacuum environments (10-7 mbar - 50 mbar). Results from the recent β-NMR experiments with 31Mg+ ions performed at TRIUMF, the former tests at the ISOLDE, as well as future plans will be presented and discussed.
9:25 AM Keeping up the Standards: Applying New Nuclear Decay and Structure Data for Radionuclide Metrology - Patrick Regan (University of Surrey and UK National Physical Laboratory)
Keeping up the Standards: Applying New Nuclear Decay and Structure Data for Radionuclide Metrology
- Patrick Regan (University of Surrey and UK National Physical Laboratory)
9:25 AM - 9:50 AM
Room: Plenary-Longs Peak The radioactivity group based at the UK's National Physical Laboratory (NPL) is responsible for traceability of radiological standards and sources. This work requires the use of a range of novel and high-precision radiation detection systems which can be utilised to provide definitive standards of the stoichiometry, decay rate and physical nature of emissions from different samples of radioactive materials. The link in the unbroken calibration chain for measurements of activity concentrations of radiopharmaceuticals and other radioactive sources / reference materials is based at the NPL, which is responsible for the ultimate traceability to the Becquerel (Bq) within the UK. This talk will outline some of the experimental techniques which are used to provide primary and secondary standards for radioactivity calibrations based on gamma-ray and/or charged particle spectrometry and highlight the importance of robust, evaluated nuclear data in such underpinning applications. An example of the recent standardisation of the naturally occurring isotope 223Ra [1,2] will be presented. This is of particular current focus as this radionuclide is both a member of the actinium (4n+1) decay chain headed by 235U and also the main therapeutic component in the radiopharmaceutical XOFIGO© [3]. The presentation will also outline some of the other methods for the production and radiochemical separation of 236Np as a long-lived tracer for 237Np via ICP - Mass spectrometry measurements in nuclear waste management [4]. Finaly, progress on the use of a digitally-based system for primary standardisations of 60Co and 134Cs, using coincident gamma-ray spectroscopy using LaBr3(Ce) detector modules (the NANA spectrometer) will be presented [5]. References: [1] Collins, S.M; et al., 2015. Direct measurement of the half-life of 223Ra. Applied Radiation and Isotopes, 99, pp.46-53; Collins, S,M. et al., 2015. Precise measurements of the absolute γ-ray emission probabilities of 223Ra and decay progeny in equilibrium. Applied Radiation and Isotopes, 102, pp.15-28. [3] https://www.xofigo-us.com/patient/index.php [4] Larijani, C. et al., 2015. Progress towards the production of the 236gNp standard sources and competing fission fragment production. Radiation Physics and Chemistry, 116, pp.69-73. [5] Lorusso, G. et al., 2016. Development of the NPL gamma-ray spectrometer NANA for traceable nuclear decay and structure studies. Applied Radiation and Isotopes, 109, pp.507-511.
9:50 AM Understanding of Decay Heat and the Reactor Anti-neutrino Spectrum Using Total Absorption Spectroscopy - Aleksandra Fijalkowska (Rutgers University)
Understanding of Decay Heat and the Reactor Anti-neutrino Spectrum Using Total Absorption Spectroscopy
- Aleksandra Fijalkowska (Rutgers University)
9:50 AM - 10:15 AM
Room: Plenary-Longs Peak Total Absorption Spectroscopy is a unique technique characterized by high efficiency detection of gamma-ray radiation. This property, used in the study of beta decay of unstable nuclei, allows for the total detection of the deexcitation path of daughter nuclei. This makes it an ideal technique to establish the true beta-decay feeding pattern, especially for the decays of nuclei suffering from the Pandemonium Effect [1]. Recent studies show that the measurements of fission products by total absorption spectroscopy are extremely important to understanding the decay heat and anti-neutrino spectrum emitted from nuclear reactors [2]. Decay heat is determined on the basis of the average energy of gamma and beta radiation emitted in the beta decay of fission products. Incomplete knowledge of the decay schemes, in particular, omission of beta transitions to high-excited states, causes an underestimation of the electromagnetic part of the decay heat and a revaluation of the beta component. This was observed by comparison with direct measurements[3]. The solution is to measure the beta decay of fission products using high-efficiency systems such as total absorption spectrometers. The number of reactor anti-neutrino interactions measured by inverse-beta decay detectors is about 6% smaller than the expected number of events, which is named the reactor anti-neutrino anomaly [4]. The anti-neutrino energy spectrum, obtained from the fission product beta-decay schemes, is used to calculate the total anti-neutrino flux emitted by reactor cores and the number of anti-neutrino interactions with the detector matter. The measurements of the beta decay of fission products using the total absorption technique allow verification of the expected number of interacting reactor anti-neutrinos with matter. In this contribution we present several results of total absorption spectroscopy measurements of the beta decay of nuclides abundantly produced in the reactor core. The measurements were performed at the Holifield Radioactive Ion Beam Facility (HRIBF) with the Modular Total Absorption Spectrometer (MTAS), the largest total absorption spectrometer in the world. The results and their impact on the decay heat and anti-neutrino spectra reconstruction will be presented and discussed. References: 1. J. Hardy et al., Phys. Lett. B71, 307, 1977 2. BC. Rasco et al., PRL 117, 092501, 2016 3. T. Yoshida et al., OECD report, NEA, 2007 4. G. Mention et al., PRD 83, 073006, 2011
10:15 AM Tree-Ring-Dating of Millennial Climate Change Across Southern Africa with AMS - Simon Mullins (iThemba LABS)
Tree-Ring-Dating of Millennial Climate Change Across Southern Africa with AMS
- Simon Mullins (iThemba LABS)
10:15 AM - 10:40 AM
Room: Plenary-Longs Peak High-resolution palaeoclimate records that might contribute to testing climate models are rare and often they are inadequately resolved in terms of their chronology or the precision of the proxy. Combining disparate evidence has yielded a rainfall record for the last 200 years that is suggestive but has large errors associated with it. This record reconstructs a drying trend that is contrast with the model reconstructions and forecasts for the region of Southern Africa. In addition the high-resolution rainfall record derived from tree rings in Zimbabwe does not reflect the same interannual variability for records from the Limpopo River Valley. This research project has obtained 1000-year isotopic tree ring records that are duplicated in each of the major climate regimes in southern Africa. This was readily achieved as the existing inventory of trees that are immediately available for analysis offers high level of coverage. Tree ring analysis is a promising technique to accomplish this in terms of rainfall, but it emerges that most of the long-lived tree species in southern Africa form irregular rings that prevent the use of traditional ring analysis. It is possible to calibrate the tree isotope records at the level of precision that is required Among the tree species that demonstrably proxy palaeoclimates through isotopes, there are key species that are both long-lived and their distribution covers the main target sampling areas. The A.erioloba trees cover the more arid part of the subcontinent and they have been shown to grow to more than 1000 years in age. The southern limit of the baobab distribution represents the East/West transect that is desired, and a recent study on the age of baobabs has demonstrated that they can achieve ages in the order of 2000 years. The Podocarpus trees are from wetter areas including coastal and mountain forests and they have also been demonstrated to grow in excess of 1000 years. The conclusion that may be drawn from this is that it is feasible that a stable light isotope palaeoclimate for the broader southern African landscape may be derived from isotopic analysis of tree rings. The ring structures have been identified and their chronology is under establishment through application of radiocarbon dating at iThemba LABS with the Accelerator Mass Spectrometry (AMS) facility. The ring counting and radiocarbon chronologies will be reconciled to provide the absolute dates for the individual isotope measurements.
10:40 AM Coffee Break
Coffee Break
10:40 AM - 11:05 AM
11:05 AM Charting New Ground with ISOLTRAP: A Survey of Recent Nuclear Binding-energy Studies - Vladimir Manea (CERN, Geneva, Switzerland)
Charting New Ground with ISOLTRAP: A Survey of Recent Nuclear Binding-energy Studies
- Vladimir Manea (CERN, Geneva, Switzerland)
11:05 AM - 11:30 AM
Room: Plenary-Longs Peak In the last years the main experimental approach to the complex nuclear many-body problem has been to track the variation of nuclear properties with the number of protons and neutrons. This justifies the ever-growing number of radioactive ion beam experiments and the great importance of binding energies, which are among the first observables reaching into unexplored regions of the nuclear chart. Their trends are sensitive to a wide range of nuclear-structure phenomena of single-particle or collective type and hence they constitute, for virtually every model, an essential input quantity. In pioneering the techniques of on-line Penning-trap mass spectrometry, the ISOLTRAP experiment [1] at ISOLDE/CERN has dedicated many years of research to the study of exotic systems at various frontiers of the nuclear chart. In this work some of the most recent results will be presented. The masses of neutron-rich cadmium isotopes around 130Cd are an incursion into the effect of the N = 82 magic number below the tin isotopic chain and its impact on r-process nucleosynthesis [2], while the masses of neutron-rich copper isotopes up to 79Cu give important insight into the evolution of the Z = 28 and N = 50 “shell closures” and the double magicity of 78Ni. Midway between magic numbers, the masses of strontium, rubidium and krypton isotopes beyond N = 60 delineate the “nuclear-shape transition” in the region of nuclides of mass A = 100. Most of these new measurements have demonstrated the importance of ISOLTRAP’s multi-reflection time-of-flight mass spectrometer (MR-TOF MS) [3], either as beam purifier or as mass-measurement apparatus. Since its implementation in the ISOLTRAP setup the MR-TOF MS has become a versatile beam-analysis tool. The variety of applications of the MR-TOF MS, as well as recent advances in the implementation of the phase-imaging ion-cyclotron-resonance technique [4] at ISOLTRAP, will be presented. References: [1] Mukherjee et al., Eur. Phys. J. A 35, 1-29 (2008). [2] D. Atanasov et al., Phys. Rev. Lett. 115, 232501 (2015). [3] R. Wolf, F. Wienholtz et al., Int. J. Mass. Spectrom. 349-350, 123-133 (2013). [4] S. Eliseev et al., Phys. Rev. Lett. 110, 082501 (2013).
11:30 AM The Rare-RI Ring Ready to Explore Terra Incognita - Sarah Naimi (Riken Nishina Center)
The Rare-RI Ring Ready to Explore Terra Incognita
- Sarah Naimi (Riken Nishina Center)
11:30 AM - 11:55 AM
Room: Plenary-Longs Peak The Rare-RI Ring at the RIBF/RIKEN facility has been recently commissioned and is now ready to start its mission of measuring masses of extremely rare isotopes. The unique location of the Rare-RI Ring at the RIBF/RIKEN facility presents an extraordinary chance to measure nuclear masses in the Terra Incognita. These nuclear masses are of particular importance in understanding the synthesis of chemical elements via the r-process but also crucial in understanding nuclear structure far from stability. The Rare-RI Ring is based on the Isochronous Mass Spectrometry technique that allows reaching a mass measurement precision of 10^-6 in less than 1 ms. Therefore, making mass measurements of extremely short-lived nuclei with low production yields possible. The full operation of the Rare-RI Ring has been achieved in three commissioning stages. In this contribution, the three commissioning experiments will be summarized and the current performance will be presented. Finally, the perspective of our physics program will be shown.
11:55 AM Recent Mass Measurements for Nuclear Astrophysics at JYFLTRAP - Anu Kankainen (University of Jyvaskyla)
Recent Mass Measurements for Nuclear Astrophysics at JYFLTRAP
- Anu Kankainen (University of Jyvaskyla)
11:55 AM - 12:20 PM
Room: Plenary-Longs Peak JYFLTRAP is a cylindrical double Penning trap mass spectrometer [1] located at the Ion Guide Isotope Separator On-Line (IGISOL) [2] facility in Jyväskylä. In total, over 330 atomic masses for nuclear structure, fundamental physics and nuclear astrophysics have been measured with JYFLTRAP. In this contribution, I will focus on recent mass measurements for nuclear astrophysics obtained after the recommissioning of JYFLTRAP at the IGISOL-4 facility in 2014. In the neutron-deficient side, 31Cl [3] and 52Co [4] are among the most exotic nuclei ever studied at JYFLTRAP. Their masses are important for testing the isobaric multiplet mass equation as well as for the rapid proton capture (rp) process occurring e.g. in type I X-ray bursts. The new, more precise proton separation energy for 31Cl helps to constrain astrophysical conditions where 30S can act as a waiting point in the rp process. We have also improved the precisions of proton-capture Q-values relevant for calculating the proton-capture rates for two key reactions, 25Al(p,g)26Si and 30P(p,g)31S [5]. Accurate knowledge of the reaction rates is needed for more reliable calculations of the amount of cosmic 1809-keV gamma rays and abundances of intermediate-mass elements in novae, respectively. In the neutron-rich side, we have recently extended our studies to the heavier fission-fragment region relevant for understanding the formation of the rare-earth peak in the astrophysical r-process. References: [1] T. Eronen et al., Eur. Phys. J. A 48 (2012) 46 [2] I.D. Moore et al., Nucl. Instrum. Meth. Phys. Res. B 317 (2013) 208 [3] A. Kankainen et al., Phys. Rev. C 93 (2016) 041304(R) [4] D.A. Nesterenko et al., arXiv:1701.04069 [nucl-ex] [5] L. Canete et al., Eur. Phys. J. A 52 (2016) 124
12:20 PM Nuclear Structure Studies Based on Energy Density Functionals - Tamara Nikšić (Department of Physics, Faculty of Science, University of Zagreb)
Nuclear Structure Studies Based on Energy Density Functionals
- Tamara Nikšić (Department of Physics, Faculty of Science, University of Zagreb)
12:20 PM - 12:45 PM
Room: Plenary-Longs Peak The self-consistent nuclear mean-field framework based on universal energy density functionals provides an accurate description of ground-state properties and collective excitations over the entire nuclear chart, from relatively light to super-heavy nuclei, and from the valley of beta-stability to the particle drip-lines. Based on this framework, structure models have been developed that go beyond the mean-field approximation and take into account collective correlations related to restoration of broken symmetries and fluctuation of collective variables. These include the generator-coordinate method with projections on particle number, angular momentum and parity, the collective Hamiltonian for quadrupole and octupole degrees of freedom, the microscopic interacting boson-fermion model. Among the most interesting recent applications of this framework are studies of shape evolution and shape-phase transitions: the occurrence of rigid triaxial deformations, quadrupole and octupole shape transitions in rare-earth nuclei and light actinides, and signatures of shape transitions in odd-mass nuclei.
12:45 PM Lunch Break
Lunch Break
12:45 PM - 2:00 PM

2:00 PM Poster Winner Announcement
Poster Winner Announcement
2:00 PM - 2:10 PM
Room: Plenary-Longs Peak
2:10 PM Instrumentation for the SPES Facility - Francesco Recchia (University of Padova)
Instrumentation for the SPES Facility
- Francesco Recchia (University of Padova)
2:10 PM - 2:30 PM
The SPES Radioactive Ion Beam facility at INFN-LNL is presently in the construction phase. The facility is based on the ISOL method with an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of up to 0.75 mA. Neutron-rich radioactive ions are produced by proton induced Uranium fission at an expected fission rate of the order of 1E13 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting Linac at energies of 10 AMeV. The key feature of SPES is to provide high intensity and high-quality beams of neutron rich nuclei to perform forefront research in nuclear structure, reaction dynamics and interdisciplinary fields like medical, biological and material sciences. New instrumentation is required for operation with unstable beams and needs to be implemented coherently with the relevant milestones of the facility. Non-reaccelerated beams will be used for beta decay studies aided by the state of the art setup planned to this purpose. Reaccelerated beams, making use of direct reactions, will exploit magnetic spectrometers coupled to gamma array. The Galileo gamma spectrometer is being implemented to this purpose. An early phase of Galileo is presently operating with stable beams, selected preliminary results will be presented. For the operation with the first reaccelerated beams the AGATA tracking array will be installed at Legnaro in conjunction with a variety of ancillary detectors. A superconducting solenoid is planned to be used in conjunction with an active target and a high resolution missing mass spectrometer is under study in order to allow simultaneous measurement of excitation and de-excitation energy. Some examples of physics opportunities will be discussed.
2:30 PM High-intensity Superconducting ECR Ion Source SECRAL - Hongwei Zhao (Institute of Modern Physics, Chinese Academy of Sciences)
High-intensity Superconducting ECR Ion Source SECRAL
- Hongwei Zhao (Institute of Modern Physics, Chinese Academy of Sciences)
2:30 PM - 2:50 PM
RIB accelerator requests high power primary ion beam which actually very much depends on performance of the front-end ion source. SECRAL (Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou) is a superconducting-magnet-based ECRIS (Electron Cyclotron Resonance Ion Source) for the production of intense highly-charged heavy ion beams. It is one of the best performing ECRISs worldwide and the first superconducting ECRIS built with an innovative magnet to generate a high strength Minimum-B field for operation with heating microwaves up to 24-28 GHz. SECRAL has so far produced a good number of CW (Continuous Wave) intensity records of highly-charged ion beams, in which the beam intensities of 40Ar12+ and 129Xe26+ have exceeded 1 emA for the first time by an ion source. The great performance of SECRAL is accumulation of a number of technical advancements, such as the innovative magnet system for better plasma confinement and more effective double-frequency (24+18 GHz) heating with an optimized 24 GHz wave coupling to operate at higher wave power with improved plasma stability.SECRAL source has run into operation to deliver highly charged ion beams for HIRFL accelerator for more than 9 years and total beam time more than 30000 hours, which has demonstrated its excellent stability and reliability. This talk will present the innovative magnet structure and the latest development of SECRAL ECR ion source.
2:50 PM Production of N = 126 Nuclei and Beyond Using Multinucleon Transfer Reactions for KISS Project - Yutaka Watanabe (Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK))
Production of N = 126 Nuclei and Beyond Using Multinucleon Transfer Reactions for KISS Project
- Yutaka Watanabe (Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK))
2:50 PM - 3:10 PM
Multinucleon transfer (MNT) reaction between two heavy ions at energies around the Coulomb barrier is considered as a promising candidate to produce and investigate exotic nuclei. It is expected to provide a mean to efficiently produce especially neutron-rich nuclei around the neutron magic number of 126, which is difficult to access by other production methods. The nuclear region of the neutron magic number N = 126 has been attracting an astrophysical interest because it is the waiting point nuclei on the r-process path, which are considered as progenitors of the peak at the mass number of 195 in the solar r-abundance distribution. We have constructed the KEK Isotope Separation System (KISS) at RIKEN RIBF facility to produce, separate and measure the nuclear properties of those neutron-rich nuclei around the neutron magic number N = 126, which will be produced by the MNT reaction. KISS consists of an argon gas cell based laser ion source and an isotope separation on-line (ISOL), to produce pure low-energy beams of neutron-rich isotopes around N = 126 and to study their beta-decay properties. We adopted the reaction system of 136Xe + 198Pt, which is considered to be one of the best candidates to efficiently produce the nuclei of interest. In order to investigate the feasibility of the nuclear production of the system, we have studied the collisions between 136Xe and 198Pt at the laboratory energy of 8 MeV/nucleon by using the EXOGAM gamma-ray array coupled to the large acceptance magnetic spectrometer VAMOS++ at GANIL. In this presentation, we will show the experimental results of nuclear production by the 136Xe + 198Pt reaction system, where the promising potential of the production of new isotopes around and beyond the neutron shell N = 126 by MNT reactions were demonstrated. We will discuss about the production of those nuclei using MNT reactions at KISS.
3:10 PM Charge Breeding Techniques for European Facilities - Pierre Delahaye (GANIL)
Charge Breeding Techniques for European Facilities
- Pierre Delahaye (GANIL)
3:10 PM - 3:30 PM
Room: Plenary-Longs Peak In the frame of two european collaborative projects, EMILIE and ENSAR 2, the charge breeding techniques are being improved. While SPIRAL 1 at GANIL and SPES will use an ECR charge breeder, ISOLDE is upgrading its charge breeder. The two techniques present different advantages and drawbacks which were thoroughly studied during the past decade. The ECR charge breeder has recently benefited from different upgrades. As an example, the SPIRAL 1 charge breeder has reached a new level of performances with its upgraded vacuum, injection / extraction optics and RF coupling. Better understanding of the capture process could be obtained. Despite these progresses, the observed behavior of the charge breeding time as a function of the support gas and plasma parameters raises new questions. This behavior is presently being studied by simulation before new on-line data is obtained with the SPIRAL 1 charge breeder. Efficient acceleration of medium mass (A>40) to heavy ions to high energy requires the use of a highly performing EBIS charge breeder. ISOLDE is presently working on the improvement of the EBIS electron optics, making use of a new high-compression gun at low energies and high current and large trapping capacities. While EBIS charge breeders provide the highest charge states, the pulsed structure of the Highly Charged Ion (HCI) beam makes their use cumbersome for many experiments. The EMILIE debuncher has been constructed at LPC Caen for an easy manipulation of the longitudinal phase space of the HCI beam to match the needs of the experiments. The availability of fast and high repetition rate ion production in combination with debunching technology allows to build a versatile and flexible injection system for various linac- and cyclotron-based post acceleration schemes.
3:30 PM Towards A Single Atom Microscope for Nuclear Astrophysics - Jaideep Singh (NSCL/MSU)
Towards A Single Atom Microscope for Nuclear Astrophysics
- Jaideep Singh (NSCL/MSU)
3:30 PM - 3:50 PM
Room: Plenary-Longs Peak We are developing the technique of optically detecting individual atoms embedded in thin films of cryogenically frozen solids. Noble gas solids such as frozen neon are an attractive medium because they are optically transparent and provide efficient, pure, stable, & chemically inert confinement for a wide variety of atomic and molecular species. The excitation and emission spectra of atoms embedded in solids can be separated by up to hundreds of nanometers making optical single atom detection feasible. We propose to couple a single atom microscope (SAM) detector to a recoil separator with the goal of measuring rare nuclear reactions relevant for nuclear astrophysics. The recoil separator would minimize the heat load on SAM while allowing for isotope discrimination. This technique has the potential to capture and detect every product atom with near unity efficiency. Because of the additional selectivity provided by resonantly exciting the atomic transitions of the captured product atom, SAM would have a negligible false positive rate which would help loosen the often demanding beam rejection requirements imposed on recoil separators. Our primary focus and long term goal is to measure the Ne-22(He-4,n)Mg-25 reaction, an important source of neutrons for the s-process, in the astrophysically relevant center-of-mass energy regime. We will describe the SAM concept in more detail, some of the critical technical challenges, and our progress towards demonstrating optical single atom detection of atoms embedded inside of solid neon.
3:50 PM Next ARIS Announcement
Next ARIS Announcement
3:50 PM - 4:00 PM