Snowmass H/D White Paper discussion




Zoom link sent by e-mail

Tom: Snowmass paper deadline is March 15, 2022.  But topical group conveners need addtional time to prepare summary reports.  Kendall Mahn is preparing one for February 28, 2022 and has told at least one other group she would like a draft of their white paper by January 2022.  Kendall is giving a summary of the NF06 (cross sections) white paper statuses on Oct 7 at a conveners' meeting, and would like us to provide a one-page advertisement of what we are doing.

Leo Bellantoni:  What are the mechanics for editing the white paper?  Small changes should just go in, but larger restructuring suggestions/changes?

Tom Junk:  Yes, go ahead and add new material.  Add new structure suggestions in red text to get our attention.

Leo:  Sepcifically, we lack scientific motivation for the polarized target.

Tom:  Yes, we need to write that section.  Nuclear structure parameters impact polarization observables, and these parameters also affect measurements in nucleon-electron scattering.  Richard Hill:  even if the same form factors are accessible via electron scattering, new physics could be visible in neutrino interactions that is not visible in electron scattering -- it's a different current.

Jon Paley:  There are a number of similar/overlapping LOIs submitted and white papers in preparation.  It may be more advantageous to combine similar white papers together, or at least cross-reference them so that we present a more coherent proposal.  Specifically, the SIS/DIS white paper focuses a lot on H2/D2 measurements.  Consider merging.  Experiment overlap?  Theory for sure will help bolster the case for H2/D2.

Yellow paper for EIC:

Neutrino physics stuff start at page 241 on the file index and page 223 in the document.

Discussion on bubble chamber LDRD -- NSF equipment proposal after LDRD:  BNB is convenient, on surface, less safety concerns/expense.  Issues -- BNB flux is orders of magnitude weaker than NuMI/LBNF.  May only run until LBNF turns on.  Would like all 5 Hz. to collect enough data (how much is enough?)   The old 15-foot bubble chamber could cycle at 3 Hz but only for brief periods.  A 60-second period was needed after a burst of cycles in order for heat to transfer and get ready for another burst.

Rapid cycling or long-metastable state (30 seconds would be good) for a new bubble chamber to get all of the beam spill data.  Small prototype to be put in a charged-particle test beam.  Leo asks how data will be stored and distributed.  Bryan suggests video may be used.

BNB will be more difficult due to high rep rate (5 Hz) than NuMI or LBNF, which have <1 Hz rep rate.  Jorge: Energy spectrum in NuMI/LBNF is more relevant to physics we are interested in.  Leo:  Want to build something we can show works in the BNB and then move it.

Several members mentioned that there is a strong advantage to putting the H2/D2 detector in the same beam as other detectors -- for constraining the flux (such as with nu-e scattering) and forming ratios of cross sections between hydrogen and argon or carbon or iron.

Jorge -- a bubble chamber needs additional detectors outside -- at least an additional two chamber diameters' worth of muon detectors and energy-measuring "picket-fence" detectors.  The BEBC chamber's muon system only had two layers for the tracking and thus was not set up to measure interactions on the iron. 

The DUNE near detector will have argon, iron and carbon targets, as planned (depending on what is done between ND-LAr and SAND, but all options have significant iron).

Clarence Wret summarized current difficulties with using the old ANL/BNL bubble chamber data to tune generators.  Large systematic uncertainties (of order 10-20%), low numbers of events, and sometimes data that includes only event counts cause troubles.  Large sources of uncertainty come from the flux and scanning efficiencies.  Single pion tension between ANL and BNL -- some data are not reported, e.g. below W of 1.4 GeV from BNL.

We should be quantitative about how much we can improve not only on statistics but also systematics.  Current flux predictions from PPFX have uncertatinties of order 10%, but replica targets can get this down to 6% or so.  LBNF's flux will be very well characterized.



There are minutes attached to this event. Show them.
    • 4:00 PM 4:20 PM
      White Paper Preparation 20m
      Speaker: Thomas Junk (Fermilab)
    • 4:20 PM 4:40 PM
      H2/D2 Topics 20m
      Speaker: Bryan Ramson
    • 4:40 PM 5:00 PM
      Generator Tuning Needs from H2/D2 Data 20m
      Speakers: Clarence Wret, Clarence Wret