论文标题
几个硬X射线光子计数像素阵列检测器中的背景速率
Background Rates in Several Hard X-Ray Photon Counting Pixel Array Detectors
论文作者
论文摘要
研究了几个像素阵列探测器中的背景速率，以期在非常低率的实验中使用硬质量，> 6 keV，X射线使用它们，例如以<0.1/s/cm^2的信号速率。在弹簧-8的实验地板上具有未屏蔽的0.75 mm厚的CDTE传感器的检测器的测量背景事件速率从0.4/s/cm^2不等，带有6 KeV下级鉴别剂（LLD）阈值（LLD）阈值到0.2/s/s/cm^2，具有75 kev lld thelheslold。在17 keV阈值下，具有1 mm厚硅传感器的检测器的背景较小，3KeV阈值降至〜0.07/s/cm^2的背景。这些速率由地面源（例如，从混凝土中的痕量杂质发出的伽玛射线）主导，只有较小的贡献，<0.01/s/cm2，直接检测到宇宙射线MUONS（CRMS）。 15毫米PB屏蔽可将测得的速率降低至CDTE中的<0.05/s/cm2，硅硅含量<0.02/s/cm^2 in 1 mm硅。 Additional processing, "time slicing", as may be used in low-rate experiments where backgrounds may be most problematic, is shown to reduce the background rates further, to < 0.004/s/cm^2 with the silicon sensor, and to between 0.002 and 0.02/s/cm^2 for CdTe, where the exact value for CdTe depends sensitively on the detector threshold, and the use of the retriggering and/or the use of dual歧视阈值。背景率表示为歧视阈值，屏蔽和处理的功能。我们还讨论了可以通过切片来引入的检测器动态范围的大小和校正的限制。最后，我们提供了一个使用时间切片的示例。
Background rates in several pixel array detectors are investigated with an eye toward using them with hard, >6 keV, x-rays in very low-rate experiments - e.g. at signal rates <0.1/s/cm^2. Measured background event rates for a detector with an unshielded 0.75 mm thick CdTe sensor on the experimental floor at SPring-8 varied from 0.4/s/cm^2 with a 6 keV lower-level discriminator (LLD) threshold to 0.2/s/cm^2 with a 75 keV LLD threshold. The background for a detector with a 1 mm thick silicon sensor was smaller, ~0.08/s/cm^2 for a 3keV threshold dropping to ~0.07/s/cm^2 at a 17 keV threshold. These rates are dominated by terrestrial sources, such as gamma rays emitted from trace impurities in concrete, with only a small contribution, <0.01/s/cm2, from direct detection of cosmic ray muons (CRMs). 15 mm of Pb shielding reduces the measured rates to < 0.05/s/cm2 in CdTe and to <0.02/s/cm^2 in 1 mm silicon. Additional processing, "time slicing", as may be used in low-rate experiments where backgrounds may be most problematic, is shown to reduce the background rates further, to < 0.004/s/cm^2 with the silicon sensor, and to between 0.002 and 0.02/s/cm^2 for CdTe, where the exact value for CdTe depends sensitively on the detector threshold, and the use of the retriggering and/or the use of dual discriminator thresholds. Background rates are presented as functions of discriminator threshold, shielding, and processing. We also discuss the magnitude of, and the correction for, the limitation of the detector dynamic range that can be introduced by the time slicing. Finally, we present one example where time slicing was used.
