Grant: Subatomic Physics Envelope - Research Tools and Instruments

Using the TRIUMF neutral atom trap (TRINAT) we can detect recoiling nuclei with only a few 100 eV of kinetic energy from the beta decay of laser-cooled and trapped radioactive atoms. Measuring coincidences with betas then lets us measure the neutrino momentum event-by-event. With modern atomic techniques, we can also achieve very high spin polarization, and we have the unique feature of measuring the polarization in situ of the decaying nuclei. We seek part per thousand accuracy of several decay observables, looking for deviations from the Standard Model of particle physics to search for additional interactions. All TRINAT experiments have relied on one tunable single-frequency high-power ring laser to collect and confine the atoms, pumped by a high-power argon ion laser. The argon ion laser was declared obsolete by the manufacturer several years ago, and despite their best effort basis to support the known perishable part, this is becoming increasingly unreliable and producing unacceptable amounts of downtime, most recently including ISAC beamtime loss for an important test run. New technology has produced a much more efficient and reliable class of lasers that can replace this argon ion pump laser, and we request one. We are pursuing two high-priority experiments approved by the TRIUMF EEC. The second item in this equipment grant would minimize a decay background from our atomic physics probe of the polarization of 37K, a mixed Fermi/Gamow-Teller decay that is sensitive to all of the physics pursued by the community in the beta decay of the neutron. The third item is needed for a more precise electric field needed to measure the beta-nu angular correlation in the pure Fermi decay of 38mK.