ORNL的SANS仪器管探测器几何畸变校正
Corrections for the Geometric Distortion of the Tube Detectors on SANS Instruments at ORNL
摘要：
橡树岭国家实验室高通量同位素反应堆的小角度中子散射仪器最近将面积探测器从最初安装的大型单体积交叉线探测器升级为交错排列的线性位置敏感探测器阵列，其设计基于ORNL Sputron中子源的EQ-SANS仪器。LPSD阵列的特定几何形状要求对传统上采用的数据减少方法进行修改。本文介绍了两种校正LPSD阵列几何畸变的方法，并对这两种方法进行了比较。第一种方法应用从使用与测量样品相同的配置执行的检测器灵敏度测量导出的校正。在这里提出的第二种方法中，将为LPSD导出的立体角校正应用于在数据简化过程期间在任何仪器配置中收集的数据，并结合在几何失真可忽略的足够长的相机长度处收集的检测器灵敏度测量。这两种方法产生一致的结果，并产生一个最大偏差的修正数据从各向同性散射样本小于0.05的动量转移到最大的0.8 A-1。结果是广泛适用于任何SANS仪器采用LPSD阵列探测器，这将是越来越普遍的仪器具有较高的入射通量在世界各地的各种中子散射设施。
英文摘要：
The small-angle neutron scattering instruments at the Oak Ridge National Laboratory High Flux Isotope Reactor recently upgraded the area detectors from the large, single volume crossed-wire detectors originally installed to staggered arrays of linear position-sensitive detectors, based on the design used on the EQ-SANS instrument at ORNL Spallation Neutron Source. The specific geometry of the LPSD array requires that approaches to data reduction traditionally employed be modified. Here, two methods for correcting the geometric distortion produced by the LPSD array are presented and compared. The first method applies a correction derived from a detector sensitivity measurement performed using the same configuration as the samples are measured. In the second method presented here, a solid angle correction derived for the LPSDs is applied to data collected in any instrument configuration during the data reduction process in conjunction with a detector sensitivity measurement collected at a sufficiently long camera length where the geometric distortions are negligible. Both methods produce consistent results and yield a maximum deviation of corrected data from isotropic scattering samples of less than 0.05 for momentum transfers up to a maximum of 0.8 A-1. The results are broadly applicable to any SANS instrument employing LPSD array detectors, which will be increasingly common as instruments having higher incident flux are constructed at various neutron scattering facilities around the world.
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