面向脉冲星导航的聚焦型X射线探测器测试标定方法研究

通过脉冲星辐射信号特征研究和空间观测需求分析,提出了一种面向导航应用的X射线探测器测试方法.首先推导了X射线光子欠探测概率公式,分析了不同星源流量及不同探测器时间分辨率下对光子探测能力的影响.通过数值模拟方法建立了脉冲到达时间与脉冲轮廓相似度的关系.处理了我国硬X射线调制望远镜的Crab脉冲星观测数据,研究了不同能段脉冲轮廓差异.其次,系统地研究了面向导航应用的X射线探测器测试及处理方法,并利用地面测试系统完成了一款自主研发的聚焦型X射线探测器测试工作.通过数据分析得到,聚焦型探测器本底噪声为3.63×10^-5ph/(cm^2·s^-1),工作能区为0.2~22.7keV,时间分辨率为4.17μs,空间响应约为5′,能量非线性为0.52%,能量分辨率优于200eV@5.7keV,典型探测效率为39.18%@4.51keV.聚焦型X射线探测器在弱脉冲信号及强背景噪声下,均能还原出Crab脉冲星脉冲轮廓,在2 400s内能够探测到辐射流量弱于背景噪声10倍的脉冲信号.结果表明,该款聚焦型探测器性能优秀,能够满足导航脉冲星(如PSR B1509)的空间观测需求,也验证了测试方法的可行性.

Research on the Test and Calibration Method of a Focusing X-ray Detector for Pulsar Navigation

A testing method for X-ray detector is proposed through the study of the characteristics of pulsar radiation signals and the analysis of space observation requirements.Firstly,based on the photon radiation model,the probability formula of X-ray photon under detection is deduced,and the influences of different source flux and different detector time resolution on photon detection ability are analyzed.The relationship between pulse arrival time and the similarity of pulse profile is established by numerical simulations.And the observations of the crab pulsar of hard X-ray modulation telescope is processed,the pulse profile characteristics of the Crab pulsar at different energy are studied.Secondly,the testing and processing methods of X-ray detector for pulsar navigation are studied systematically,and the testing work of a self-developed focused X-ray detector is completed by using the ground testing system.The test results show that the background noise of the focused detector is 3.63×10^-5 ph/(cm^2·s^-1),the working energy range is 0.2~22.7 keV,the time resolution is 4.17μs,and the spatial response is about 5′.The energy linearity of the detector is good,the integral nonlinearity is 0.52%.The energy resolution of the detector is better than 200 eV at five characteristic energy spectra,and the best detection efficiency is 39.18%@4.51 keV.Under the condition of weak pulse signal and strong background noise,the detector can accurately restore the pulse profile of Crab pulsar.The signal-to-noise ratio and similarity of the pulse profile increase with the increase of pulse flow and the decrease of background noise.The detector can detect the pulse signal whose radiation flux is 10 times less than the background noise in 2400 s.The results show that the focused detector has excellent performance and can meet the space observation requirements of navigation pulsars(eg.PSR B1509),so the feasibility of the testing method is also verified.