分类: 核科学技术 >> 核科学与技术 提交时间: 2024-01-06
摘要: POLAR-2 is a gamma-ray burst (GRB) polarimeter that is designed to study the polarization in GRB radiation emissions, aiming to improve our knowledge of related mechanisms. POLAR-2 is expected to utilize an on#2;board polarimeter that is sensitive to soft X-rays (210 keV), called low-energy polarization detector (LPD). We have developed a new soft X-ray polarization detector prototype based on gas microchannel plates (GMCPs) and pixel chips (Topmetal). The GMCPs have bulk resistance, which prevents charging-up effects and ensures gain stability during operation. The detector is composed of low-outgassing materials and is gas-sealed using a laser welding technique, ensuring long-term stability. A modulation factor of 41.28% 0.64% is obtained for a 4.5 keV polarized X-ray beam. A residual modulation of 1.96% 0.58% at 5.9 keV is observed for the entire sensitive area.
分类: 物理学 >> 核物理学 提交时间: 2016-08-31
摘要: The quality of PMT signal is one of the key items for a large and high precision neutrino experiment, like Daya Bay, JUNO, while most of the experiments are affected by the PMT signal overshoot from its positive HV-single cable scheme. For JUNO prototype detector, we have a detailed study on the PMT overshoot and successfully reduced the ratio of overshoot amplitude to signal to ~1% from previous typical ~10%, with no affection to PMT other parameters. Furthermore, we calculated that the overshoot is a result of discharging of capacitors in the HV-signal splitter and the PMT voltage divider. The study result is extremely important for JUNO and other similar experiments.