Precise measurement of the angular correlation parameter a sub( beta v) in the beta decay of super(35) Ar with LPCTrap

Precise measurements in the beta decay of the super(35) Ar nucleus enable to search for deviations from the Standard Model (SM) in the weak sector. These measurements enable either to check the CKM matrix unitarity or to constrain the existence of exotic currents rejected in the V-A theory of the SM. For this purpose, the beta -v angular correlation parameter, a sub( beta )v, is inferred from a comparison between experimental and simulated recoil ion time-of-flight distributions following the quasi-pure Fermi transition of super(35)Ar super(1+) ions confined in the transparent Paul trap of the LPCTrap device at GANIL. During the last experiment, 1.5 x 10 super(6) good events have been collected, which corresponds to an expected precision of less than 0.5% on the a sub( beta )v value. The required simulation is divided between the use of massive GPU parallelization and the GEANT4 toolkit for the source-cloud kinematics and the tracking of the decay products.