Schematic diagram of field of satellites

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... GECAM project consists of two small satellites running in the same orbital plane but opposite orbital phases Fig. 1) to make all-sky complete coverage monitoring [8]. The payloads of each satellite include 25 gamma-ray detectors (GRDs), 8 charged particle detectors (CPDs), and Electronics module (EBOX) (Fig. 2, where the round one represents GRD and the square one represents CPD). The 25 GRD modules are all installed in the dome of the satellite, ...

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... resolution is an important performance index of GRD. Figure 10 illustrates the energy spectrums of GRD when the energies of simulated gamma rays (vertical incidence) are 8 keV, 59.5 keV, 662 keV, and 1 MeV, respectively. As revealed in the simulation results, the number of photoelectrons received by SiPMs increase linearly with the increase in incident energy of the particles. ...

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... the energy is 59.5 keV, the energy resolution result obtained by simulation can reach 13.4%, which is better than the index requirement when the energy resolution is 18% at 59.5 keV. Figure 11 presents the detector efficiency curve of GRD full-energy peak obtained by simulation. As shown, the results imply that the full-energy peak detection efficiency of GRD is about 70% at 8 keV, which meets the index requirement for being larger than 50% at 8 keV. ...

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... LaBr3 crystals are produced in three batches and there are some differences in SiPM array and preamplification electronic, the GRDs performance is different. Fig. 12. The signal output by the detector was amplified by the main amplifier plug-in ORTEC 671, with gain of 14 and molding time of 0.5 μs, and the Gaussian molding function was enabled. The impulse amplitude spectrum output by the main amplifier plug-in was collected by multi-channel analyzer ORTEC ASPEC-927. The test result is as presented ...

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... Fig. 12. The signal output by the detector was amplified by the main amplifier plug-in ORTEC 671, with gain of 14 and molding time of 0.5 μs, and the Gaussian molding function was enabled. The impulse amplitude spectrum output by the main amplifier plug-in was collected by multi-channel analyzer ORTEC ASPEC-927. The test result is as presented in Fig. 13. According to the test results, the energy resolution of GRD to 241 Am radioactive source is generally better than 16%, which satisfies the design requirement of satellite. Finally, 50 GRDs were selected by energy resolution from the 68 GRDs assembled and installed on two satellites of ...

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... the sake of verifying the reliability and structural stability properties of GRD, a verification level random vibration test was made on the 50 GRDs to be installed on satellite (Fig. 14) under the same mechanical test conditions as formal prototype of payload. The GRDs were installed in applicable positions on the dome and then subjected to random vibration test under mechanical conditions of the entire payload. The test conditions are demonstrated in Table ...

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... indicated in the test results (Fig. 15), before and after the test, the GRD maintains in stable performance, with relative change in peak less than 3% and that in energy resolution even smaller, which meets the requirements for use in ...

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... the random vibration test, the relative change in peak of radioactive source of GRD is less than 3%, presenting a stable performance. Further, it is also needed to conduct performance calibration test on GRDs on the ground and scale the E-C relation, energy resolution, and other performances of the GRDs to prepare for the inversion of on-orbit Fig. 15 Before and after GRD Random vibration test, the change of 59.5 keV Full-energy Peak data. This part of the work will be discussed in subsequent ...