CHARACTERIZATION OF CCD DETECTOR ELECTRONICS FOR RECORDING WEAK X-RAY SCATTERING

用于记录弱 X 射线散射的 CCD 探测器电子器件的特性

• 批准号: 7370628
• 负责人: MARC NIEBUHR
• 金额: $ 1.37万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7370628
• 关键词: CHARACTERIZATION; CCD; DETECTOR; ELECTRONICS; RECORDING

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The BL4-2 MarCCD165 detector displays a relatively large A/D converter offset fluctuation, making it highly challenging to record very weak signal levels accurately, despite the significant improvements in data precision due to radial integration of scattering signals. This is in fact a universal problem with almost all of optic fiber coupled CCD x-ray detectors. A project was initiated to determine the exact level of electronic stability required for actual solution x-ray scattering experiments. We measured offset level fluctuation as a function of time and assessed the exact degree of signal fluctuation with respect to the level of scattering signals from dilute protein and buffer solutions. We observed offset fluctuation of as much as 2-4 AD converter unit per pixel on average, corresponding approximately to 2-4 12 keV x-ray photons. We implemented a blank offset level measurement immediately prior to each x-ray exposure in Blu-ICE, and we have as a result been able to record weak signal levels more accurately on many occasions. We communicated our results to the detector manufacturer, who as a result implemented two major improvements within our annual maintenance contract: replacing some of key electronic components in the read out electronic circuit and implementing a compensation algorithm in the programmable field gate array in the circuit. Furthermore, measures were taken to stabilize the temperature of the detector electronics inside the BL4-2 experimental hutch in order to further stabilize the performance of the temperature-sensitive electronic components primarily responsible for the offset fluctuation. The detector now performs with improved stability and gives much more reliable buffer subtraction in most solution scattering studies.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子弹和调查员（PI）可能已经从其他NIH来源获得了主要资金，因此可以在其他清晰的条目中代表。列出的机构适用于该中心，这不一定是调查员的机构。 BL4-2 MARCCD165检测器显示出相对较大的A/D转换器抵消器的波动，尽管由于散射信号的径向整合，因此数据精度有显着提高，因此准确地记录非常弱的信号水平是高度挑战性的。实际上，这是一个普遍的问题，几乎所有光纤耦合CCD X射线探测器。启动了一个项目，以确定实际解决方案X射线散射实验所需的精确电子稳定性水平。我们测量了偏移水平的波动，并评估了相对于稀释蛋白和缓冲溶液的散射信号水平的确切信号波动的确切程度。我们平均观察到每个像素的偏移量高达2-4 AD转换器单元，大约相当于2-4 12 KEV X射线光子。在Blu-Ice中，我们在每次X射线曝光之前立即实施了空白的偏移液测量，因此我们能够在许多情况下更准确地记录弱信号级别。我们将结果传达给了检测器制造商，结果他们在我们的年度维护合同中实现了两个重大改进：替换了读取电子电路中的一些关键电子组件，并在电路中的可编程场门阵列中实施了补偿算法。此外，采取了衡量量稳定BL4-2实验储藏室内检测器电子的温度，以进一步稳定温度敏感的电子成分的性能，主要负责偏移波动。现在，检测器的稳定性提高，并在大多数溶液散射研究中可提供更可靠的缓冲液减法。