Speaker
Takeshi Yamamoto
(Department of Physics, Tohoku University)
Description
At the J-PARC facility, several light hypernuclei will be studied via gamma-ray spectroscopy at the K1.8 beam line as a Day-1 experiment (E13). We will study 4{$lambda}He to solve puzzle of charge symmetry breaking and 19{$lambda}F to study spin-dependent {$lambda}N interaction in sd-shell at the initial stage of E13. Gamma rays from the hypernuclei are detected by a new germanium(Ge) detector array, Hyperball-J, for ultra high energy deposit rate. The array consists of 32 coaxial Ge detectors surrounded by PWO counters for background suppression. One of the array’s features is a large absolute photo-peak efficiency, simulated as 6.1% for 1-MeV gamma ray. Other is mechanical cooling of Ge crystal for radiation-hardness. The Ge detector-cooler unit achieved comparable energy resolution with that of the LN2 cooling. PWO counters were introduced for fast background suppression instead of BGO counters used in the past experiments. The dead time due to decay time is shorter. We have also developed a Hyperball-J control system and tested with a few detector units mounted to frame. The construction of the array is at the final stage, and the current status of E13 will be reported.
Primary author
Takeshi Yamamoto
(Department of Physics, Tohoku University)
