分类： 天文学 >> 天文学 提交时间： 2023-02-19
Z. H. An
X. L. Sun
D. L. Zhang
S. Yang
X. Q. Li
X. Y. Wen
K. Gong
X. H. Liang
X. J. Liu
Y. Q. Liu
Y. G. Li
S. L. Xiong
Y. B. Xu
Fan Zhang
X. Y. Zhao
C. Cai
Z. Chang
G. Chen
C. Chen
Y. Y. Du
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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
D. L. Zhang
X. L. Sun
Z. H. An
X. Q. Li
X. Y. Wen
K. Gong
C. Cai
Z. Chang
G. Chen
C. Chen
Y. Y. Du
M. Gao
R. Gao
D. Y. Guo
J. J. He
D. J. Hou
Y. G. Li
C. Y. Li
G. Li
L. Li
摘要： The discovery of gravitational waves and gamma-ray bursts heralds the era of multi-messenger astronomy. With the adoption of two small satellites to achieve the all-sky monitoring of gamma-ray bursts, the gravitational wave high-energy electromagnetic counterpart all-sky monitor (GECAM) possesses a quasi-real-time early warning ability and plays an important role in positioning the sources of gravitational waves and in subsequent observations.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Y. Q. Liu
K. Gong
X. Q. Li
X. Y. Wen
Z. H. An
C. Cai
Z. Chang
G. Chen
C. Chen
Y. Y. Du
M. Gao
R. Gao
D. Y. Guo
J. J. He
D. J. Hou
Y. G. Li
C. Y. Li
G. Li
L. Li
X. F. Li
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
J. J. He
Z. H. An
W. X. Peng
X. Q. Li
S. L. Xiong
D. L. Zhang
R. Qiao
D. Y. Guo
C. Cai
Z. Chang
C. Chen
G. Chen
Y. Y. Du
M. Gao
R. Gao
K. Gong
D. J. Hou
C. Y. Li
G. Li
L. Li
摘要： As the main detector of the GECAM satellite, the calibration of the energy response and detection efficiency of the GRD detector is the main content of the ground-based calibration. The calibration goal requires the calibrated energy points to sample the full energy range (8 keV-2 MeV) as much as possible. The low energy band (8-160 keV) is calibrated with the X-ray beam, while the high energy band (>160 keV) with radioactive sources. This article mainly focuses on the calibration of the energy response and detection efficiency in the 8-160 keV with a refined measurement around the absorption edges of the lanthanum bromide crystal. The GRD performances for different crystal types, data acquisition modes, working modes, and incident positions are also analyzed in detail. We show that the calibration campaign is comprehensive, and the calibration results are generally consistent with simulations as expected.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Xiao-Yun Zhao
Shao-Lin Xiong
Xiang-Yang Wen
Xin-Qiao Li
Ce Cai
Shuo Xiao
Qi Luo
Wen-Xi Peng
Dong-Ya Guo
Zheng-Hua An
Ke Gong
Jin-Yuan Liao
Yan-Qiu Zhang
Yue Huang
Lu Li
Xing Wen
Fei Zhang
Jing Duan
Chen-Wei Wang
Dong-Li Shi
摘要： Realtime trigger and localization of bursts are the key functions of GECAM, which is an all-sky gamma-ray monitor launched in Dec 10, 2020. We developed a multifunctional trigger and localization software operating on the CPU of the GECAM electronic box (EBOX). This onboard software has the following features: high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation, dedicated localization algorithm optimized for short and long bursts respetively, short time latency of the trigger information which is downlinked throught the BeiDou satellite navigation System (BDS). This paper presents the detailed design and deveopment of this trigger and localization software system of GECAM, including the main functions, general design, workflow and algorithms, as well as the verification and demonstration of this software, including the on-ground trigger tests with simulated gamma-ray bursts made by a dedicated X-ray tube and the in-flight performance to real gamma-ray bursts and magnetar bursts.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Xuejian Ma
Fei Zhang
Zhaodong Chu
Ji Hao
Xihan Chen
Jiamin Quan
Zhiyuan Huang
Xiaoming Wang
Xiaoqin Li
Yanfa Yan
Kai Zhu
Keji Lai
摘要： The outstanding performance of organic-inorganic metal trihalide solar cells benefits from the exceptional photo-physical properties of both electrons and holes in the material. Here, we directly probe the free-carrier dynamics in Cs-doped FAPbI3 thin films by spatiotemporal photoconductivity imaging. Using charge transport layers to selectively quench one type of carriers, we show that the two relaxation times on the order of 1 microsecond and 10 microseconds correspond to the lifetimes of electrons and holes in FACsPbI3, respectively. Strikingly, the diffusion mapping indicates that the difference in electron/hole lifetimes is largely compensated by their disparate mobility. Consequently, the long diffusion lengths (3 ~ 5 micrometers) of both carriers are comparable to each other, a feature closely related to the unique charge trapping and de-trapping processes in hybrid trihalide perovskites. Our results unveil the origin of superior diffusion dynamics in this material, crucially important for solar-cell applications.
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