Seminar Details

Feasibility test of exotic particle searches in the decay of trapped rubidium isomers

Tao Kong, University of British Columbia
Monday, December 17, 11:00 AM - Special Seminar
NSCL Lecture Hall

In the two-body final state of a gamma decay, photons have the same momentum as the recoiling nucleus. This would produce a single peak at P = E/c in the recoiling momentum spectrum of the nucleus. On the other hand, if massive particles are emitted in nuclear transitions instead of gamma photons, the recoiling nucleus will have a lower momentum than E/c. Measuring the recoiling momentum of the decay daughters allows us to indirectly search for any massive particle emitted in nuclear transitions, independent of particles' lifetime or their interactions in any detector.

In this talk, I will present the experimental tests of searching for exotic particle emissions in the decay of laser-trapped ⁸⁶Rb isomers (6^- to 2^- transition) by measuring the recoiling momentum of the decay daughters in a COLTRIM setup. I will discuss the experimental setups, photoionization schemes, the achieved 3% momentum resolution and the 10% sensitivity to exotic particle emissions. The photoionization scheme is a two-stepwise procedure, including the Doppler-free two-photon transition from the 5S_1/2 to the 5D_5/2 states by a 778 nm laser, and from the 5D_5/2 state into the continuum by a 1064 nm laser. By analyzing the measured 5S_1/2 to 5D_5/2 two-photon transition spectra, we deduced the related isotope shifts and hyperfine constants in radioactive Rb isotopes. The precision we achieved in the isotope shift measurements allows us to deduce the specific mass shifts between the 5S_1/2 to 5D_5/2 states with 4 - 28 MHz precision./p>