Research for Radiation Damage of CCD Vertex Detector

CCD顶点探测器辐射损伤研究

• 批准号: 11640247
• 负责人: ABE Koya
• 金额: $ 1.79万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640247/
• 关键词: CCD; Radiation damage; e^+e^- linear collider; Vertex detector; Surface damage; 電子線型加速器; 短寿命重粒子; 電子線形加速器

Two subjects were studied for an application of CCD's as vertex detector at nearby room temperature in future e^+e^- linear collider JLC.1) Noise hits should be suppressed to less than 10^<-5> for total number of pixels more than 10^8 for the vertex detector. As dark currents strongly depend on an operating temperature, can we obtain enough S/N ratio at the room temperature?A dependence of the dark current on accumulation time and S/N using ^<55>Fe X-ray (5.89 keV) source were measured in order to verify the applicability. Four CCS's with pixel size of 12×12, 24×24, and 48×48 μm^2, which are commercially available, were used in the study. A mode of Multi-Pinned-Phase (MPP) were adapted to reduce the dark current. We concluded that the enough S/N could be obtained with the CCD of pixel size smaller than 24×24 μm^2 and a faster driver circuit of CCDs with charge transfer speed more than 5 MHz.2) Radiation of 150 krad is expected for 10 year operation of JLC.Can CCD has sufficient radiation hardness in the environment near collision point of JLC?Negative driving voltage V^<MPP>_<cc> at which CCD is converted to MPP mode and Charge Transfer Inefficiency (CTI) were measured before and after irradiation of ^<60>Co γ-ray of about 200 Ci. After irradiation of 27 krad V^<MPP>_<cc> moved from -6.5 V to -9.8 V and CTI increased from 1.0×10^<-6> to 3.5×10^<-6>. After an additional exposure of 18 krad the operation of the CCD became difficult. This means that this type of CCDs tested now can not be used to operation of JLC for more than two years.We conclude that enough S/N can be obtained for the operation of CCDs at the room temperature. However we need more extensive R＆D to get adequate radiation hardness for the operation of JLC over ten years.

在未来的e^+e^-直线对撞机JLC中，应用CCD作为近室温下的顶点探测器，研究了两个问题：1）对于<-5>顶点探测器，当总像素数大于10^8时，噪声命中应被抑制到10^8以下;由于暗电流强烈依赖于工作温度，我们能在室温下获得足够的S/N比吗？为了<55>验证该方法的适用性，用5.89keV的~（60）Fe X射线源测量了暗电流与积累时间和信噪比的关系。研究中使用了四种市售的CCS，像素大小分别为12×12、24×24和48×48 μm^2。采用多钉扎相位（MPP）模式来降低暗电流。结果表明，采用像素尺寸小于24×24 μm^2的CCD和电荷转移速度大于5 MHz的CCD驱动电路，可以获得足够的信噪比。2）JLC运行10年的辐射强度预计为150 krad，CCD在JLC碰撞点附近的环境中是否具有足够的抗辐射能力？测量<MPP><cc>了200 Ci ~（-1）Co γ射线辐照前后CCD转换为MPP模式时的负驱动电压V^ _（？）和电荷转移效率（CTI）<60>。27 krad辐照后，V^<MPP>_<cc>（1 - 6. 5 V）增加到-9. 8 V，CTI从1. 0 ×10 ~ 4增加<-6>到3. 5 ×10 ~ 4<-6>。在额外曝光18 krad后，CCD的操作变得困难。这意味着目前测试的这类CCD不能用于JLC的运行超过两年，我们认为CCD在室温下可以获得足够的S/N。然而，我们需要更广泛的研发，以获得足够的辐射硬度运行JLC超过十年。

项目成果

K.D.Stefanov 他: "Electron and Neutron Radiation Damage Effect on a Two Phase CCD"IEEE transaction Nuclear Science. 47-3. 1280-1291 (2001)

K.D.Stefanov 等人：“两相 CCD 上的电子和中子辐射损伤效应”IEEE 交易核科学 47-3 1280-1291 (2001)。

K.D.Stefanov 他: "Investigation of the radiation performance of CCD sensors in a vertex detector application"Nuclear Instrument & Methods in Nuclear Physics Research. A436-1. 182-187 (1999)

K.D.Stefanov 等人：“顶点探测器应用中 CCD 传感器的辐射性能研究”核物理研究中的仪器和方法 A436-1（1999）。