分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jiahuan Zhu
Hong Li
Hua Feng
Jiahui Huang
Xiangyun Long
Qiong Wu
Weichun Jiang
Massimo Minuti
Saverio Citraro
Hikmat Nasimi
Dongxin Yang
Jiandong Yu
Ge Jin
Ming Zeng
Peng An
Luca Baldini
Ronaldo Bellazzini
Alessandro Brez
Luca Latronico
Carmelo Sgro
摘要： PolarLight is a space-borne X-ray polarimeter that measures the X-ray polarization via electron tracking in an ionization chamber. It is a collimated instrument and thus suffers from the background on the whole detector plane. The majority of background events are induced by high energy charged particles and show ionization morphologies distinct from those produced by X-rays of interest. Comparing on-source and off-source observations, we find that the two datasets display different distributions on image properties. The boundaries between the source and background distributions are obtained and can be used for background discrimination. Such a means can remove over 70% of the background events measured with PolarLight. This approaches the theoretical upper limit of the background fraction that is removable and justifies its effectiveness. For observations with the Crab nebula, the background contamination decreases from 25% to 8% after discrimination, indicative of a polarimetric sensitivity of around 0.2 Crab for PolarLight. This work also provides insights into future X-ray polarimetric telescopes.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Ying Tan
Xuelei Cao
Weichun Jiang
Xiaobo Li
Bin Meng
Wanchang Zhang
Sheng Yang
Tao Luo
Yudong Gu
Liang Sun
Xiaojing Liu
Yuanyuan Du
Jiawei Yang
Yanjun Xu
Jinyuan Liao
Yupeng Xu
Fangjun Lu
Liming Song
Shuangnan Zhang
摘要： Introduction: The Medium Energy X-ray telescope (ME) is a collimated X-ray telescope onboard the Insight hard X-ray modulation telescope (Insight-HXMT) satellite. It has 1728 Si-PIN pixels readout using 54 low noise application-specific integrated circuits (ASICs). ME covers the energy range of 5-30 keV and has a total detection area of 952 cm2. The typical energy resolution of ME at the beginning of the mission is 3 keV at 17.8 keV (Full Width at Half Maximum, FWHM) and the time resolution is 255 us. In this study, we present the in-orbit performance of ME in its first 5 years of operation. Methods: The performance of ME was monitored using onboard radioactive sources and astronomical X-ray objects. ME carries six 241Am radioactive sources for onboard calibration, which can continuously illuminate the calibration pixels. The long-term performance evolution of ME can be quantified using the properties of the accumulated spectra of the calibration pixels. In addition, observations of the Crab Nebula and the pulsar were used to check the long-term evolution of the detection efficiency as a function of energy. Conclusion: After 5 years of operation, 742 cm2 of the Si-PIN pixels were still working normally. The peak positions of 241Am emission lines gradually shifted to the high energy region, implying a slow increase in ME gain of 1.43%. A comparison of the ME spectra of the Crab Nebula and the pulsar shows that the E-C relations and the redistribution matrix file are still acceptable for most data analysis works, and there is no detectable variation in the detection efficiency.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Ying Tan
Xuelei Cao
Weichun Jiang
Xiaobo Li
Bin Meng
Wanchang Zhang
Sheng Yang
Tao Luo
Yudong Gu
Liang Sun
Xiaojing Liu
Yuanyuan Du
Jiawei Yang
Yanjun Xu
Jinyuan Liao
Yupeng Xu
Fangjun Lu
Liming Song
Shuangnan Zhang
摘要： Introduction: The Medium Energy X-ray telescope (ME) is a collimated X-ray telescope onboard the Insight hard X-ray modulation telescope (Insight-HXMT) satellite. It has 1728 Si-PIN pixels readout using 54 low noise application-specific integrated circuits (ASICs). ME covers the energy range of 5-30 keV and has a total detection area of 952 cm2. The typical energy resolution of ME at the beginning of the mission is 3 keV at 17.8 keV (Full Width at Half Maximum, FWHM) and the time resolution is 255 us. In this study, we present the in-orbit performance of ME in its first 5 years of operation. Methods: The performance of ME was monitored using onboard radioactive sources and astronomical X-ray objects. ME carries six 241Am radioactive sources for onboard calibration, which can continuously illuminate the calibration pixels. The long-term performance evolution of ME can be quantified using the properties of the accumulated spectra of the calibration pixels. In addition, observations of the Crab Nebula and the pulsar were used to check the long-term evolution of the detection efficiency as a function of energy. Conclusion: After 5 years of operation, 742 cm2 of the Si-PIN pixels were still working normally. The peak positions of 241Am emission lines gradually shifted to the high energy region, implying a slow increase in ME gain of 1.43%. A comparison of the ME spectra of the Crab Nebula and the pulsar shows that the E-C relations and the redistribution matrix file are still acceptable for most data analysis works, and there is no detectable variation in the detection efficiency.
点击量
待评议
点击量
下载量
评论
