Speaker
Description
Following the experiment EXP. 22. 72, which aimed to measure the 10C superallowed beta-decay branching ratio (BR), the new experiment had been suggested based on the improvement of the experimental setup. The increase in the maximum validation rate of AGATA from 1 kHz to 4 kHz per crystal enables us to obtain a four-fold increase in the statistics. In addition, the relay of the beam switching system and the AGATA trigger prevent the problem of time misalignment between the start of the beam-on period and the end of the data writing. The shielding for the scattered protons inside the chamber was optimized, and a custom Tantalum target holder was designed to reduce the counting rate per crystal in AGATA. The 1-day test beamtime (EXP. 24. 12) demonstrated that the experiment would be feasible.
The experiment was performed in July-August 2025. An 8-MeV, 30-pnA (2-pnA for in-beam) proton beam from the XTU-Tandem impinged on a stack of 1-mg/cm2 10B targets with carbon backing. The beam was on the target for 60 s and off for 120 s to measure the beta-delayed gamma rays. The measurement with a continuous beam was performed as well. We observed more than 1.5 million 1022-keV 10C beta-delayed gamma rays, which would give an opportunity to reach a per-mil-level precision for the superallowed beta-decay BR measurement. The progress on the analysis will be presented. Moreover, some preliminary results on the EXP. 22. 72 will be introduced.