DETECTOR DEVELOPMENT AND UPGRADE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 目标：升级我们现有的两个面积探测器系统公司(ADSC)Q315探测器，开始购买最先进的现代像素阵列探测器(PAD)，促进和参与探测器开发计划(单片、高度集成的模块)。尽管它们得到了好评，但我们没有收到最后两个项目的资金。我们报道Pad购买只是因为我们正在寻找其他途径，而我们在这里不报道第三个项目。 在所有五条PXRR光束线上，用面阵探测器系统公司的面阵探测器采集了大分子晶体的衍射图。其中两个是部署在我们的波动光束线X25和X29上的Q315，一个是X12C弯曲磁铁光束线上的最新型号Q210，以及两个在X26C和X12B上的第一代慢速Q4探测器。 毫不奇怪，用户和工作人员强烈喜欢使用三个较新的探测器进行实验，这些探测器在大约一秒内完成图像读出，他们不愿等待Q4渲染图像所需的15秒。这种对速度的强调不仅反映了用户的不耐烦，还反映了数据收集方法的先进状态以及实验人员在快速结晶学决策方面的高水平培训。 结果在2008年夏天，我们发送了我们的一台Q315探测器，第二台是2002年购买的，用于工厂升级到Q315r规格。它配备了新的内部读出电子设备和新的热电冷却器，现在可以将ccd保持在所需的低工作温度。新的图像采集计算机取代了过时的计算机。当在x29重新调试时，我们确认标准2x2硬件入库读出模式的增益符合预期，包括测角开销在内，在0.8秒内实现了读出，低于最初的1.4s。这与x29波荡器系列的典型曝光时间1秒或更短形成了鲜明对比。 H.Robinson博士在X29上仔细减少了大量用户数据收集，结果显示，与升级前进行的类似研究相比，信噪比有所改善。这些用于测量弱反射的重要增益与制造商指定的电子读取噪声降低30%是一致的。对个别衍射图的仔细检查还使他发现了一个由强烈的饱和布拉格反射引起的微小成像伪影。虽然在数据缩减方面无关紧要，但它帮助ADSC找到了造成这种缺陷的电子原因，并修改了他们的电路。 考虑到通过探测器升级可以实现的性能提升，我们计划对2000年购买的第二个Q315进行整修，并为X25提供服务。 我们已经成功地构建了一个基于Linux的EPICS IOC来控制我们所有的ADSC探测器。该方法使用了APS编写的areaDetector模块，取代了以往作为CBass测控程序一部分的图像采集过程。虽然这是引入用于晶体观察的数字摄像机的副产品，但这一努力是朝着统一EPICS下的所有设备控制、实现快速和并行的命令传输迈出的重要一步(见计划)。 计划我们努力获得一个像素阵列探测器(PAD)，用于我们的一条波纹光束线，以便更快地向用户、邮寄人员和客户提供更高质量的数据。由于这一具体目标得到了积极的审查，但在我们的赠款续期中没有资金，我们与我们在石溪大学的合作者H.Li博士合作，并将提交一份S10高端仪器赠款提案，用于购买PAD。 在接下来的一年里，我们将把EPICS的控制扩展到样品主轴和快门。当这个硬件和软件相结合的项目完成后，可以使用面向对象的EPICS控制体系结构并行管理衍射仪、测角仪和探测器功能。对于使用当前型号的CCD探测器的衍射计操作，将获得快门到快门暂停的减少，使我们更接近探测器技术所规定的图像读出时间限制。更重要的是，将控制统一到一个独立的系统中，基本上提供了我们开发和评估具有连续主轴旋转的无快门数据收集所需的技术和方法，就像我们使用像素阵列探测器部署的那样。 重要意义一旦像素阵列探测器在NSLS波荡器光束线上可用，我们将在数据质量和数量上实现比基于CCD的探测器所能实现的显著提高。由于12赫兹的快速成帧速率、不到4ms的惊人的读出死区时间、对零值的完全背景辨别以及单一的点扩展函数，在晶轴的无快门连续扫描期间可以采用精细的切片数据采集方法。这种全新的方法在前所未有的动态范围内为数据简化和索引程序提供了精确定义和狭义的布拉格斑点，从而以更高的分辨率产生更完整、更清晰的数据集，并最终产生更好的结构。

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. Objectives The objectives stated in the recent renewal proposal are these: upgrade our two existing Area-Detector Systems Corp. (ADSC) Q315 detectors, initiate the purchase of a modern pixel-array detector (PAD) that is at the state of the art, contribute to and participate in a detector-development program (monolithic, highly-integrated modules). Although they were favorably reviewed, we did not receive funding for the last two projects. We report on the PAD purchase only because we're looking for other avenues, and we do not report on the third project here. Diffraction patterns of macromolecular crystals are collected at all five of the PXRR beamlines with the excellent CCD-based area detectors from Area Detector Systems Corporation. Two of these are Q315s deployed on our undulator beamlines X25 and X29, one is a recent model Q210 at the X12C bending magnet beamline, and two are slow, first generation Q4 detectors at X26C and X12B. Not surprisingly, users and staff strongly prefer performing experiments with the three newer detectors that complete image readouts in about one second, and they hesitate to wait the 15 seconds that it takes a Q4 to render its image. More than impatience of users, this emphasis on speed reflects the advanced status of data collection methods as well as the high level of experimenter training in fast crystallographic decision-making. Results  In summer 2008 we sent one of our Q315 detectors  the second one, purchased in 2002  for factory upgrades to Q315r specifications. It was equipped with new internal readout electronics and new thermo-electric coolers that now can keep the CCDs at the required low operating temperature. New image gathering computers replaced obsolescent ones. When re-commissioned at X29, we confirmed that the gains in the standard 2x2 hardware binned readout mode met expectations and, including goniometry overhead, achieved a readout in 0.8 seconds, down from the original 1.4s. This compares well to typical exposure times of 1 sec or less at the X29 undulator line. Careful reduction of numerous user data collections by Dr. H. Robinson at X29 revealed that the signal-to-noise ratio had improved when compared to similar studies carried out before the upgrade. These important gains for the measurement of weak reflections are consistent with a manufacturer-specified 30% reduction of the electronic read noise. Meticulous inspection of individual diffraction patterns also led him to discover a small imaging artifact caused by strong, saturating Bragg reflections. Though inconsequential in data reduction, it helped ADSC to find the electronic cause of this imperfection and to revise their circuitry. Given the verified performance gains achievable through detector upgrades, we have scheduled the refurbishment of our second Q315, purchased in 2000, and serving X25. We have succeeded in building a Linux-based EPICS IOC to control all of our ADSC detectors. This method uses the areaDetector module written by at the APS, and replaces the image-gathering process that used to be part of the CBASS experiment-control program. While a side product of introducing digital-video cameras for crystal observation, this effort is an important step towards unifying all device controls under EPICS, achieving fast and parallel command transmissions (see Plans.) Plans  We endeavor to acquire a pixel array detector (PAD) for use on one of our undulator beam lines to provide higher quality data, faster, to users and Mail-in staff and clients. Because this specific aim was favorably reviewed, but not funded in our grant renewal, we teamed up with Dr. H. Li, our collaborator at Stony Brook University, and will submit a S10 High-End Instrumentation grant proposal for the acquisition of a PAD. In the year ahead, we will extend EPICS control to the specimen spindle and the shutter. When this combined hardware and software project is complete, diffractometer, goniometer, and detector functions can be managed in parallel using the object-oriented EPICS control architecture. For diffractometer operation with current model CCD detectors, a reduction of the shutter-to-shutter pause will be obtained, bringing us closer to the image readout time limit imposed by detector technology. More importantly, unifying controls into one self-contained system essentially provides the technology and methods that we will need to develop and evaluate shutter-less data collections with continuous spindle rotation of the kind we would deploy with a pixel array detector. Significance  Once a pixel array detector becomes available on an NSLS undulator beamline, we will achieve dramatic gains in data quality and quantity beyond those possible with CCD-based detectors. Owing to the fast framing rate of 12 Hz, the astonishingly short readout dead-time of less than 4 ms, the complete discrimination against background to zero values, and the unitary point spread function, fine slicing data collection methods can be employed during a shutter-less continuous sweep of the crystal spindle. This entirely new method provides data-reduction and indexing programs with sharply defined, and narrowly boxed, Bragg spots over an unprecedented dynamic rage, thus yielding more complete, crisper datasets at higher resolution, and ultimately better structures.