Status of a carbon Ξ - atomic X-ray measurement at J-PARC (1)

The interaction between the Ξ^- baryon and the nucleon (Ξ-N interaction) has been discussed for a long time, but it has not been clarified experimentally very well. To study the Ξ-N interaction, we will carry out the experiment, J-PARC E96. J-PARC E96 experiment measures the energy of the X ray from orbital transitions of Ξ^- in the carbon atom. We want to measure 55 keV X ray ((n, L) = (4, 3) → (3, 2) transition) and 154 keV X ray ((3, 2) → (2, 1) transition). In the case of (3, 2) → (2, 1) transition, the energy of X ray (154 keV) is expected to be slightly changed due to the Ξ-N interaction. In this experiment, the Ξ^- baryon will be produced via the (K^-, K⁺) reaction with the AFT (Active Fiber Target) at the J-PARC K1.8 beamline. Since AFT is composed of a lot of scintillating fibers, the particle tracking in the target can be performed. After tagging the Ξ^- stop events in the target, Ge detectors surrounding the AFT measure X rays from Ξ atoms. In this presentation, I will talk about overview of the E96 experiment and data analysis of our Ge detector in the commissioning run carried out in June 2023.