Speaker
Description
The CKM matrix, associated with quark mixing, is expected to be unitary within the framework of the Standard Model. Therefore, a precise test of the CKM matrix unitarity is one of the precision frontiers in the search for physics beyond the Standard Model. The element $V_{ud}$, which dominates the first-column unitarity condition, can be precisely determined from superallowed beta decay. Recently, theoretical uncertainty in $V_{ud}$ has been reduced, providing motivation to further improve from the experimental side. The superallowed beta-decay of $^{10}$C has shown a slight deviation from the averaged $Ft$ (corrected $ft$) value. Furthermore, the fact that $^{10}$C superallowed beta-decay has the largest impact to the scalar current search motivates a new high-precision measurement.
We performed a series of experiments, EXP.22.72, EXP.24.012, EXP.24.044 at INFN-LNL using the AGATA HPGe tracking array, aimed at remeasuring the superallowed beta-decay branching ratio of $^{10}$C. In the experiments, we used (p,n) and (p,p$'$) reactions induced by proton beams with energies between 8 and 10~MeV accelerated from the INFN-LNL Tandem on a 1~mg/cm$^{2}$ thick $^{10}$B target. AGATA was employed to measure the gamma rays from the reactions. As a preliminary result for the first experiment, EXP.22.72, we obtained the half-life for the $^{10}$C superallowed beta decay, which shows consistency with the reference value. Moreover, the analysis of the branching ratio for the dataset of EXP.22.72 and EXP.24.044 is in progress. I will present some preliminary results of the experiments and discuss future perspectives.