Speaker
Dr
Matthew Redshaw
(Central Michigan University)
Description
The results of solar, atmospheric, and reactor neutrino oscillation experiments have provided strong evidence for a non-zero neutrino mass. However, these measurements determine only the difference between the squared-masses of the neutrino mass eigenstates. The absolute neutrino mass scale is still unknown. Beta-decay experiments utilizing 3H and 187Re have obtained the most stringent upper limits on the (anti) electron neutrino mass of 2 eV. An emerging alternative method for a direct neutrino mass determination is based on calorimetric electron capture spectroscopy (ECS) of 163Ho. The ECHO collaboration in Europe, and the NUMECS collaboration in the USA aim for sub-eV sensitivity to the electron neutrino mass using this method. In both the beta-decay and EC experiments the neutrino mass is determined from a fit to data near the end-point of the decay energy spectrum. The end-point energy for zero neutrino mass, which corresponds to the Q-value for the decay, is a free parameter in the fit. Hence, an independent measurement of the Q-value is extremely important for interpreting experimental results and checking for possible systematic effects.
At CMU we are developing a high-precision double Penning trap mass spectrometer: the Central Michigan University HIgh Precision Penning trap (CHIP-TRAP), which will employ a simultaneous cyclotron frequency comparison technique using pairs of ions confined in two separate traps. This will reduce the effect of magnetic field fluctuations. The Q-value, defined as the mass difference between parent and daughter atoms, can be determined via
Q = mp – md = (mp – me)(1 – R),
where R = fc,p/fc,d is the cyclotron frequency ratio for ions of the parent and daughter species. CHIP-TRAP will utilize ions of 163Ho and the daughter 163Dy produced by a laser ablation ion source. This will minimize the amount of 163Ho, which must be synthesized, required for the measurement. A Q-value determination to ~1 eV is required for the 163Ho ECS experiments, corresponding to a fractional precision of ~5 parts-per-trillion in the cyclotron frequency ratio. In this presentation we will describe the current status of CHIP-TRAP, and of tests of ion production via laser ablation of the stable 165Ho isotope.
Primary author
Dr
Matthew Redshaw
(Central Michigan University)
Co-authors
Mr
Curtis Hunt
(Central Michigan University)
Mr
Ishara Ratnayake
(Central Michigan University)
Mr
Lance Sharp
(Central Michigan University)
Mr
Paul Hawks
(Central Michigan University)
Mr
Richard Bryce
(Central Michigan University)