Precision measurements in nuclear β ‐decay with LPCTrap
The experimental achievements and the current program with the LPCTrap device installed at the LIRAT beam line of the SPIRAL1‐GANIL facility are presented. The device is dedicated to the study of the weak interaction at low energy by means of precise measurements of the β−ν angular correlation parameter. Technical aspects as well as the main results are reviewed. The future program with new available beams is briefly discussed.
The MORA project
The MORA (M atter’s O rigin from the R adioA ctivity of trapped and oriented ions) project aims at measuring with unprecedented precision the D correlation in the nuclear beta decay of trapped and oriented ions. The D correlation offers the possibility to search for new CP-violating interactions, complementary to searches done at the LHC and with electric dipole moments. Technically, MORA uses an innovative in-trap orientation method which combines the high trapping efficiency of a transparent Paul trap with laser orientation techniques. The trapping, detection, and laser setups are under development. The project will first focus on the proof-of-principle of the in-trap laser orientation technique, before the actual measurement of the D correlation in the decay of 23Mg+ ions is undertaken firstly at JYFL and then later, at GANIL, with full sensitivity to new physics.
Measurement of the β - ν Correlation using Magneto-optically Trapped N a 21
The beta-neutrino correlation coefficient, ${a}_{\ensuremath{\beta}\ensuremath{\nu}}$, in $^{21}\mathrm{N}\mathrm{a}$ is inferred from detecting the ${\ensuremath{\beta}}^{+}$ and low-energy recoil daughter nucleus. $^{21}\mathrm{N}\mathrm{a}$ is produced at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and 800 000 atoms are maintained in a magneto-optical trap. From the measured time of flight of recoil ions in the presence of a drift electric field, we find ${a}_{\ensuremath{\beta}\ensuremath{\nu}}=0.5243\ifmmode\pm\else\textpm\fi{}0.0091$. There may be a dependence on the trapped atom population. This and other systematic uncertainties are discussed.