分类: 物理学 >> 核物理学 提交时间: 2016-09-14
摘要: We infer the emission positions of twin kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low mass X-ray binaries (NS-LMXBs) based on the Alfven wave oscillation model (AWOM). For most sources, the emission radii of kHz QPOs cluster around a region of 16-19 km with the assumed NS radii of 15 km. Cir X-1 has the larger emission radii of 23-38 km than those of the other sources, which may be ascribed to its large magnetosphere-disk radius or strong NS surface magnetic field. SAX J1808.4-3658 is also a particular source with the relative large emission radii of kHz QPOs of 20 - 23 km, which may be due to its large inferred NS radius of 18 - 19 km. The emission radii of kHz QPOs for all the sources are larger than the NS radii, and the possible explanations of which are presented. The similarity of the emission radii of kHz QPOs (16-19 km) for both the low/high luminosity Atoll/Z sources is found, which indicates that both sources share the similar magnetosphere- disk radii.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The Gravitational Wave Burst High-energy Electromagnetic Counterpart All-sky Monitor (GECAM), consists of 2 small satellites that each contain 25 LaBr3 (lanthanum bromide doped with cerium chloride) detectors and 8 plastic scintillator detectors. The detector signals are read out using a silicon photomultiplier (SiPM) array. In this study, an acquisition algorithm for in-orbit real-time SiPM array data is designed and implemented, and the output event packet is defined. Finally, the algorithm's efficacy for event acquisition is verified.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Background: Each GECAM satellite payload contains 25 gamma-ray detectors (GRDs), which can detect gamma-rays and particles and can roughly localize the Gamma-Ray Bursts (GRBs). GRD was designed using lanthanum bromide (LaBr3) crystal as the sensitive material with the rear end coupled with silicon photomultiplier (SiPM) array for readout. Purpose: In aerospace engineering design of GRD, there are many key points to be studied. In this paper, we present the specific design scheme of GRD, the assembly and the performance test results of detectors. Methods: Based on Monte Carlo simulation and experimental test results, the specific schematic design and assembling process ofGRDwere optimized. After being fully assembled, theGRDswere conducted performance tests by using radioactive source and also conducted random vibration tests. Result and conclusion: The test results show that all satellite-borne GRDs have energy resolution <16% at 59.5 keV, meeting requirements of satellite in scientific performance. The random vibration test shows that GRD can maintain in a stable performance, which meets the requirement of spatial application.