为研究用于X射线脉冲星导航的探测系统性能,推导了在光子计数模式下探测系统的信噪比和最小可探测功率的关系表达式,并搭建测量信噪比和最小可探测功率的实验装置.测量了系统的最小可探测功率以及在不同光功率、不同累积时间和不同阈值电压条件下探测系统的信噪比.通过对X射线光子到达时间的测量,构造了X射线脉冲累积轮廓.实验表明: 随着光功率和累积时间的增加,累积脉冲轮廓的信噪比提高,累积脉冲轮廓趋于光滑;当阈值电压为-150 mV时,信噪比为26.3,累积脉冲轮廓最优;系统的最小可探测功率为3.5×10-16 W.

In order to assess the performance of detection system for X-ray pulsar navigation, the expression of the signal-to-noise ratio (SNR) and the minimum detectable power are derived in the photon counting mode of the system. Experiment system to measure the SNR and the minimum detectable power is setup. The minimum detectable power is measured; the SNRs at different integration time, optical power and threshold voltage are calculated. The X-ray pulse profile is reconstructed by measuring the time of arrival (TOA) of the X-ray photons. Experimental results show that the SNR of the pulse profile is improved and the curve of the pulse profile tends to smooth with the increasing of optical power and the integration time; the SNR is 26.3 and the pulse profile is optimal when the threshold voltage is -150 mV; the minimum detectable power of the system is 3.5×10-16 W.