IMR-MIP: High-Detection-Efficiency and High-Spatial-Resolution Thermal Neutron Imaging System for the Spallation Neutron Source using Pixelated Semiconductor Neutron Detectors

这是来自材料研究仪器的奖励——主要仪器项目支持散裂中子源的像素化半导体中子探测器的开发。该探测器将采用高探测效率、高空间分辨率的热中子成像系统。中子束是一种强大的探测器，用于探测物质的结构，因此，国际散裂中子源（SNS）目前正在橡树岭国家实验室建造。要使用这种源，需要使用专门的衍射仪来分选不同的中子能量。使用这种仪器的关键是中子探测器，它可以测量被寻找结构的样品散射的中子。传统上，在离样品许多米的地方使用大型充满气体的中子探测器，这需要很大的距离来提供散射中子的必要角分辨率。该项目将导致一系列新型半导体中子探测器，可以测量非常接近样品的散射中子，从而消除样品和探测器之间空气中的中子相互作用以及传统测量技术中固有的其他复杂性。所提出的器件的独特之处在于，它利用具有均匀间隔的蚀刻腔（窄孔或细沟）的矩阵的半导体晶圆，其中填充了中子反应材料。这些孔被蚀刻到器件的前部，使得穿透深度达到半导体（50至300微米）。有了这样的空腔，再加上传统的表面涂层，半导体晶片就完全被中子反应物质渗透了。一组半导体二极管将被生产出来，它们具有用于SNS的必要特性，即(1)接近50%的高热中子本质探测效率，(2)小于100微米的空间分辨率，(3)小于10微秒的相对较快的响应时间，(4)耐辐射损伤，(5)对伽马射线背景不敏感。此外，这些设备只需要很小的电源就可以运行，坚固耐用，非常可靠，而且比传统的充气探测器便宜得多。目前没有这样的成像阵列存在，无论是作为商业或原型设备，也没有一个目前在世界上任何地方正在开发。本研究的目标是利用一种新的技术制造原型中子成像探测器，该探测器可以满足三个SNS实验的仪器要求，即VULCAN工程衍射仪、SNAP高压衍射仪和单晶衍射仪（SCD）。该项目的目标是为VULCAN衍射仪建立一个高分辨率线性阵列。探测器将有1000个像素条，每条长4厘米，宽100微米。一个专用集成芯片（ASIC），目前还没有，也将设计和制造操作小型化的探测器阵列。因此，随着中子探测器阵列，将开发一个ASIC读取中子感应信号从中子探测器阵列。这项技术可以转移到SNAP和SCD衍射仪。该项目将涉及至少8名学生参与项目的各个阶段，包括开发、测量、制造和分析任务。通过向这个项目引进年轻的实验人员，探测器专业知识将在美国得到发展。这是至关重要的，因为这个领域剩下的实验学家已经很少了。该项目将为至少五名具有实践经验并参与国家实验室（ORNL/SNS）研究人员的研究生提供高级学位。这是来自材料研究仪器的奖励——主要仪器项目支持散裂中子源的像素化半导体中子探测器的开发。该探测器将采用高探测效率和高空间分辨率的热中子成像系统，该散裂中子源（SNS）将于2007年开始运行，需要多种中子探测器用于光束端口仪器。其中一些仪器需要小型、高效率、高空间分辨率的中子成像探测器。这些仪器包括VULCAN工程衍射仪、SNAP高压衍射仪和单晶衍射仪（SCD）。中子成像装置必须对伽马射线不敏感，同时保持接近50%的高热中子本征探测效率。SNAP和SCD衍射仪的空间分辨率必须至少为500微米，VULCAN衍射仪的空间分辨率必须至少为100微米。最后一个要求是中子成像探测器必须具有相对较快的响应时间，小于10微秒。目前还没有这样的仪器存在，无论是作为商业设备还是原型设备，而且目前在世界上任何地方都没有开发。目前的研究目标是使用一种新的技术制造原型中子成像探测器，以满足SNS对VULCAN、SNAP和SCD衍射仪的仪器要求。新设备在室温下工作，结构紧凑，坚固耐用，设计可靠。蒙特卡罗模型结合MCNP代码将用于指导优化器件设计的开发和制造。初步结果表明，50%的检测效率目标是可以实现的。提出的目标是为VULCAN衍射仪建立一个高分辨率线性阵列。探测器将有1000个像素条，每条长4厘米，宽100微米。一个专用集成芯片（ASIC），目前还没有，将设计和制造操作小型化的探测器阵列。因此，随着中子探测器阵列，将开发一个ASIC读取中子感应信号从中子探测器阵列。所开发的技术可以转移到SNAP和SCD衍射仪的空间阵列。该项目将涉及至少8名学生参与项目的各个阶段，包括开发、测量、制造和分析任务。通过让年轻的实验人员参与到项目中来，专业知识在美国得到了发展。这是至关重要的，因为这个领域剩下的实验学家已经很少了。该项目将为至少五名具有实践经验并参与国家实验室（ORNL/SNS）研究人员的研究生提供高级学位。

This is award from the Instrumentation for Materials Research - Major Instrumentation Project supports the development of pixilated semiconductor neutron detector for the Spallation Neutron Source. The detector will a high-detection-efficiency and high-spatial-resolution thermal neutron imaging system.Neutron beams are a powerful probe used to elicit the structure of matter, and, for this reason, the international Spallation Neutron Source (SNS) is currently being constructed at Oak Ridge National Laboratories. To use such a source, specialized diffractometers, which sort out different neutron energies, are used. Key to the use of such instruments are neutron detectors that can measure neutrons scattered by a specimen whose structure is sought. Traditionally, large gas-filled neutron detectors located many meters from the specimen are used, the large distances necessary to provide the necessary angular resolution of the scattered neutrons. This project will lead to an array of novel semiconductor neutron detectors that can measure scattered neutrons very close to the specimen, thereby eliminating neutron interactions in the air between specimen and detector and other complications inherent in traditional measurement techniques.The proposed device is unique in that it utilizes a semiconductor wafer with a matrix of evenly spaced etched cavities (narrow holes or thin trenches) filled with the neutron reactive material The holes are etched into the front of the device such that the penetrations reach deeply (50 to 300 microns) into the semiconductor. With such cavities, together with traditional surface coatings, the semiconductor wafer is thus completely permeated with neutron reactive material. An array of semiconductor diodes will be produced with the necessary properties for use at the SNS, namely (1) a high thermal-neutron intrinsic detection efficiency that approaches 50%, (2) a spatial resolution of less than 100 microns, (3) a relatively fast response time of less than 10 microseconds, (4) is resistant to radiation damage, and (5) is insensitive to the gamma-ray background. In additiona, these devices require only small power sources to operate, are rugged and extremely reliable, and are much less costly than traditional gas-filled detectors.No such imaging array presently exists, either as a commercial or a prototype device, nor is one presently under development anywhere in the world. The goal of the present research is to manufacture prototype neutron imaging detectors using a new and novel technology that can meet the instrumentation requirements for three SNS experiments, namely the VULCAN Engineering Diffractometer, the SNAP High Pressure Diffractometer, and the Single Crystal Diffractometer (SCD). The target of the project is to build a high-resolution linear array for the VULCAN Diffractometer. The detector will have 1000 pixel strips, each 4 cm long and 100 microns wide. An Application Specific Integrated Chip (ASIC), not presently available, will also be designed and manufactured to operate the miniaturized detector array. Hence, along with the neutron detector array, an ASIC will be developed to read the neutron-induced signals from the neutron detector array. This technology can then be transferred to the SNAP and SCD diffractometers.This project will involve at least eight students in various phases of the project, including the development, measurement, fabrication, and analysis tasks. By introducing young experimentalists to this project, detector expertise will be developed within the United States. This is vital since there are very few remaining experimentalists in this area. This project will result in advanced degrees for at least five graduate students with practical experience and involvement with researchers at a national laboratory (ORNL/SNS).This is award from the Instrumentation for Materials Research - Major Instrumentation Project supports the development of pixilated semiconductor neutron detector for the Spallation Neutron Source. The detector will a high-detection-efficiency and high-spatial-resolution thermal neutron imaging systemThe Spallation Neutron Source (SNS), due to begin operation in the year 2007, requires a variety of neutron detectors for the beam port instruments. Several of the instruments need small, high-efficiency, high-spatial-resolution neutron imaging detectors. Those instruments include the VULCAN Engineering Diffractometer, the SNAP High Pressure Diffractometer, and the Single Crystal Diffractometer (SCD). The neutron imaging devices must be insensitive to gamma rays while retaining high thermal-neutron intrinsic detection efficiency that approaches 50%. The spatial resolutions must be at least 500 microns for the SNAP and SCD Diffractometers, and 100 microns for the VULCAN Diffractometer. A last requirement is that the neutron-imaging detector must have a relatively fast response time less than 10 microseconds. No such instrument presently exists, either as a commercial or a prototype device, and is not presently under development anywhere in the world. It is the goal of the present research effort to manufacture prototype neutron imaging detectors using an new and novel technology that can meet the instrumentation requirements at the SNS for the VULCAN, SNAP, and SCD Diffractometers. The new devices operate at room temperature, are compact, rugged, and reliable in design. Monte Carlo modeling coupled with the MCNP codes will be used to guide the development and fabrication of optimized device designs. Preliminary results indicate that the 50% detection efficiency target is achievable. The target of the proposed effort is to build a high-resolution linear array for the VULCAN Diffractometer. The detector will have 1000 pixel strips, each 4 cm long and 100 microns wide. An Application Specific Integrated Chip (ASIC), not presently available, will be designed and manufactured to operate the miniaturized detector array. Hence, along with the neutron detector array, an ASIC will be developed to read the neutron-induced signals from the neutron detector array. The technology developed can be transferred to the SNAP and SCD Diffractometers for the spatial arrays. This project will involve at least eight students in various phases of the project, including the development, measurement, fabrication, and analysis tasks. By introducing young experimentalists to the project through key involvement in tasks, expertise is developed within the United States. This is vital since there are very few remaining experimentalists in this area. This project will result in advanced degrees for at least five graduate students with practical experience and involvement with researchers at a national laboratory (ORNL/SNS).