Development of position sensitive Gamma-ray detector

点击翻译按钮获取中文摘要

The measurement of radiative decay of the Λ(1405) can give important information of the structure of the Λ(1405), which is the Kbar-N bound state whether or not. In this research, we proposed to develop a position sensitive Gamma-ray-detector to study a radiative decay of the Λ(1405) by using Hyperon Time-Projection-Chamber, which is being built to explore an existence of the H-dibaryon and the 3-body hadronic nucleon resonances at the J-PARC hadron experimental facility.A full simulation was performed to estimate the resolution and acceptance of the Λ(1405) based on the GEANT4 toolkit. The size of the Gamma-ray-detector was optimized based on the reconstructed position resolution. By assuming the 64 segments of the detector, the acceptance of the radiative decay is estimated to be 83.3%, while the background reduction is obtained to be more than 85%.The test bench with 13 mm^2 size of MPPC and 2 x 1 x 80 cm^3 long plastic scintillator was performed. We obtained the timing resolution versus the ADC gain by using beta rays from Sr-90. The estimated timing resolution at MIP is about 130 ps. The thin plastic scintillator, however, is desired, because the space limitation of the super conducting Helmholtz-Coil was come. We newly fabricated new MPPC board to be optimize the gain and light collection efficiency. The board is being tested and the test board will be shared with the TPC hodoscope.The simulation and test results were presented at the HYP2015 at Tohoku University in Sep. In addition, the progress has been reported at the E42 and E45 collaboration meeting.