The postdoctoral fellowship position concerns the development of simulation tools for the analysis of the first experiments undertaken within the frame of the Matter’s Origin from RadioActivity (MORA) project [1].The MORA project gathers experts of ion manipulation in traps and laser orientation methods for searches of New Physics (NP) in nuclear beta decay, looking for possible hints to explain the matter-antimatter asymmetry observed in the Universe. The precise measurement of the so-called triple D correlation is sensitive to Time reversal violation, and via the CPT theorem, to CP violation. As such, the measurement of D in nuclear beta decay is a complementary probe to the electric dipole moment of the neutron. It is particularly sensitive to the existence of Leptoquarks, which are hypothetical gauge bosons appearing in the first theories of baryogenesis, and in numerous theories beyond the Standard Model.
The symmetries of the MORA detection system and the well-controlled parameters of the trapped and polarized ion cloud permit to aim at a final sensitivity of a few 10^-5 on D. Such a sensitivity is about one order of magnitude better than present limits on D, from measurements in neutron and ¹⁹Ne decay. It should permit, in addition to look for signs of CP violation, to probe for the first time the so-called Final State Interaction (FSI) effects. The FSI effects, caused by the electromagnetic interaction of the recoiling nucleus with the b particle, are expected to mimic a tiny non-zero D at a level which varies from 10^-5 to 10^-4, depending on the decaying nucleus. Their estimates rely on rather old calculations (1970’s), which are presently being revised by theoreticians within the MORA project.
The ultimate sensitivity of MORA depends on how well systematic effects are kept under control. To this intent, dedicated studies and analysis tools have to be developed. The aim of the postdoctoral fellowship will be to develop these tools, taking part to the supervision of the work done by PhD students for the Geant 4 simulation of the individual detectors of MORA, and by combining the results of these simulations with ion tracking simulations done by LPC Caen. The result of this work should be a high-level simulation tool permitting to predict systematic effects and eventually to analyze the first measurements carried-out within the MORA project. First experiments will be carried out during 2021 and 2022 in JYFL, Finland with the aim of demonstrating the in-trap polarization technique and of the D correlation measurement. We will first focus on ²³Mg⁺ with a half-life of 11.3s, which has a simple polarization scheme and will eventually be available in copious intensities at the future DESIR facility at GANIL [2] for measurements with highest sensitivity to new physics.