A PIXEL ARRAY DETECTOR FOR PROTEIN CRYSTALLOGRAPHY

在这一修订的申请中，需要资金来设计、建造和测试一个模块化的50x50像素阵列探测器，该探测器可以极快地收集数据，并且可以承受非常高的辐射水平而不会损坏。数字像素阵列探测器将由大小为150微米×150微米的硅像素探测器阵列组成，该阵列连接到也具有相同大小的像素的读出电路阵列。使用微电子方法，读出电路以ASIC芯片的形式结合了复杂的电子设备，允许一系列并行的快速读出，以实现所需的吞吐速率。一个16x16像素的原型探测器现在正在工作，并正在进行详尽的测试。需要资金将这一原型扩展到一个模块化的50x50像素探测器，该探测器可以在以后组装成一个非常大的探测器(高达2000x2000像素)。每个像素将以高达10(6)光子/秒的速率收集X射线，整个探测器的吞吐速率将为4x10(11)光子/秒。由于几乎没有读出死区，它能够在90秒内采集完整的单色数据。它配有一个可以精确到几微秒的电子快门，非常适合时间分辨的劳厄衍射实验，因为它有足够的直方图存储器来存储多达8或16张连续的照片。对于不能重复的实验，曝光时间将约为10ms或更长，并且对于3%的数据集具有足够的统计数据。对于可重复的实验，曝光时间可以小到几毫秒。这种探测器的另一个特性是它可以选择一定波长范围的X射线光子，因此它对分类劳厄衍射实验中的重叠反射非常有帮助。

In this revised application, funding is requested to design, build and test a modular 50 x 50 pixel array detector that can collect data extremely fast and that can sustain very high radiation level without damage. The Digital Pixel Array Detector will consist of an array of silicon pixel detectors of the size of 150 mu x 150 mu bump bonded to an array of readout circuits also with pixels of the same size. Using microelectronic methods, the readout circuitry, in the form of an ASIC chip, incorporated sophisticated electronics allowing a series of fast readouts in parallel to achieve the desired throughput rate. A 16x16 pixel prototype detector is now working and is being tested exhaustively. Funding is requested to extend this prototype to a modular 50 x 50 pixel detector that can be assembled later on to form a very large detector (up to 2000 x 2000 pixel). Each pixel would collect X-rays at a rate up to10 (6) photons/sec and the throughput rate for the whole detector will be 4x10(11) photons/sec. With almost no readout dead time, it is capable of collecting a complete monochromatic data in 90 seconds. It comes with an electronic shutter that can be timed down to a few microseconds, and is very well suited to time resolved Laue diffraction experiments since it will have enough histogram memory to store up to 8 or 16 successive pictures. For experiments that cannot be repeated, the exposure time would be about 10 ms or longer with enough statistics for a 3% data set. For repeatable experiments, the exposure time can be as small as a few milliseconds. Another property of this detector is that it can select a range of wavelengths of X-ray photons, therefore it can be very helpful in sorting out overlapping reflections in a Laue diffraction experiment.