Measurement of the soft X-ray response of P-channel back-illuminated CCD
Measurement of the soft X-ray response of P-channel back-illuminated CCD
复制标题
P通道背照式CCD软X射线响应的测量
DOI：
10.1016/j.nima.2012.11.187
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Shutaro Ueda
中科院分区：
文献类型：
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作者：
Shutaro Ueda;Kiyoshi Hayashida;Naohisa Anabuki;Hiroshi Nakajima;Katsuji Koyama;Hiroshi Tsunemi;Shutaro Ueda
由N型硅晶片制成的P沟道电荷耦合器件（CCD）最初是为地面光学和近红外望远镜开发的。这些CCD的厚耗尽层为硬X射线提供了高量子效率（QE）的显著优势。另一方面，软X射线的高QE是通过背照式（BI）和完全耗尽的CCD获得的，其中在入射表面上仅存在薄的死层。因此，P沟道BI CCD可以用作上级宽带X射线探测器。我们专门为定于2014年发射的X射线天文卫星ASTRO-H上的软X射线成像仪开发了这样一种设备。我们之前报道过，我们的CCD（SXI-CCD的原型）的耗尽层厚度超过200μm。在本文中，我们报告了一种新的软X射线响应的P沟道BI CCD。首先，我们照射荧光X射线的O，F，Na，Al，Si和K的SXI原型。实验结果表明，我们的CCD在软X射线响应中具有明显的低能尾结构。由于低能量尾部的强度对于较低的X射线能量是较大的，因此尾部起源于CCD表面层。然后，我们制作了一种新型的CCD应用替代处理其表面层。在同步辐射装置KEK-PF上，用0.25 ~ 1.8keV单色X射线辐照CCD，测量了CCD的软X射线响应。SXI飞行模型的表层也将采用同样的处理方法。
P-channel charge-coupled devices (CCDs) made from N-type silicon wafers were originally developed for ground-based optical and near-infrared telescopes. The thick depletion layer of these CCDs provides the significant advantage of high quantum efficiency (QE) for hard X-rays. On the other hand, high QE for soft X-rays is obtained with back-illuminated (BI) and fully depleted CCDs in which only a thin dead layer exists on the surface of incidence. Thus, P-channel BI CCDs can be applicable as superior wide band X-ray detectors. We have developed such a device specifically for the Soft X-ray Imager (SXI) on board the X-ray astronomy satellite ASTRO-H, scheduled to be launched in 2014. We previously reported that the depletion layers of our CCDs, a prototype of SXI-CCDs, have a thickness of more than 200μm. In this paper, we report a novel soft X-ray response of P-channel BI CCDs. First, we irradiate fluorescent X-rays of O, F, Na, Al, Si and K to the SXI prototype. This experiment reveals that our CCD has a significant low-energy tail structure in the soft X-ray response. Since the intensity of the low-energy tail is larger for lower X-ray energies, the tail is originated on the CCD surface layer. Then, we fabricate a new type of CCDs by applying an alternative treatment to its surface layer. The soft X-ray response of the CCD is measured by irradiation of monochromatic X-rays from 0.25keV to 1.8keV in a synchrotron facility, KEK-PF. The intensity of the low-energy tail for 0.5keV incident X-ray is one order of magnitude smaller than that for the previous CCD. The same treatment will be applied to the surface layer of the SXI flight model.