摘要：Gamma-ray polarimetry is a new and prospective tool for studying various extreme high-energy celestial objects and is of great significance for the development of astrophysics. With the rapid development of microsatellite technology, the advantages in space exploration are becoming increasingly apparent. Therefore, in this paper, we conducted a simulation study on a soft gamma-ray polarimeter for a microsatellite in space. Here, we proposed a unique design structure for the polarimeter based on the microsatellite design concept and the Compton scattering principle. And then, the detailed Monte Carlo simulations using mono-energetic gamma-ray linear polarization sources and the Crab-like sources in the energy range of 0.1-10 MeV with full consideration of the orbital background were performed. The simulation results show that the polarimeter can exhibit excellent polarization detection performance. The modulation factor is 0.80±0.01, and the polarization angles are accurate within an error of 0.2° at 200 keV for on-axis incidence. For the Crab-like sources for on-axis incidence, the polarization degrees are consistent with the set values within the error tolerance, the modulation factor is 0.76±0.01, and the minimum detectable polarization reaches 2.4% at 3σ for an observation time of 106 seconds. In addition, the polarimeter has recoil electron tracking, imaging, and powerful background suppression at a large field of view (∼2π sr). The polarimeter designed can meet the requirements of a space-soft gamma-ray polarization detector very well and has a bright research prospect.
摘要：A fully digital data acquisition system based on a field-programmable gate array (FPGA) was developed for a CsI(Tl) array at the External Target Facility (ETF)in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by γ-rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard γ and α sources. The scheme, which included a moving average filter, baseline restoration, leading-edge discrimination, moving window deconvolution and digital charge comparison was subsequently implemented on the FPGA. A good energy resolution of 5.7% for 1.33 MeV γ rays and excellent α-γ identification using the digital charge comparison method were achieved, which satisfies CsI(Tl) array performance requirements.