By using six circularly polarized laser beam, together with a superimposed magnetic field (generated by an Anti-Helmholtz coil pair) it is possible to cool and confine neutral atoms. This sample of cold atoms will then serve as our localized radioactive source. A large number of atoms can be localized to a region with a typical size of a fraction of a millimeter at a temperature of roughly 200 μK.
By instrumenting our trap chamber with the detectors for the recoil ion, the “shakeoff” electrons, and the emitted β particle we will be able to reconstruct the decay process and derive the correlation coefficients. A first stage of our experiment will be to measure the aβν coefficient, later we will use an additional laser beam to polarize the trapped sample and measure the polarization dependent correlation coefficients. The measurement of these coefficients will require us to transfer the trapped atoms from the MOT into another, fully optical trap, which will be overlaid on the MOT.
A somewhat tricky part when trapping neon (or any noble gas) is that there are no readily available lasers which have the appropriate wavelengths (since noble atoms have tightly closed shells it take a lot of energy to excite their electrons, which translates into very short wavelengths). Luckily, noble gasses have long lived (metastable) states, in which one of the outer shell electrons if moved to a higher state, not radiatively connected to the ground state. These metastable atoms behave somewhat like alkali metals and have transitions which are laser accessible. Part of our research will focus on optimizing a metastable neon source from which we will obtain our atoms for the trap. Since we will only start with a small amount of radioactive atoms, the metastable source should be as efficient as possible in order to conserve as many of the atoms (typically metastable source are about 0.01% effective, meaning that only 0.01% of the atoms are actually transferred to the metastable state).