Optimization of ray-tracing simulations to confirm performance of the GP-SANS instrument at the High-Flux Isotope Reactor

IF 1.5 3区物理与天体物理 Q3 INSTRUMENTS & INSTRUMENTATION

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment Pub Date : 2024-10-16 DOI:10.1016/j.nima.2024.169965

James M. Rogers , Matthew J. Frost , Lisa M. Debeer-Schmitt

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引用次数: 0

Abstract

The CG-2 beamline at the High Flux Isotope Reactor (HFIR) exhibits a notable discrepancy between observed count rates and the count rates we would expect based on a Monte-Carlo neutron ray-trace simulation. These simulations consistently predict count rates approximately five times greater than those observed in four separate experimental runs involving different instrument configurations. This discrepancy suggests that certain factors are causing losses in measurements that are not adequately accounted for in the simulation, in particular guide reflectivity or misalignment.

To investigate these discrepancies, a high-dimensional simulation parameter approach is applied in order to understand the losses. Region of Interest (ROI) groups along the instrument are assigned to different surfaces of the guide components within the simulation. This allows the parameters of those guide components to be varied as a group to minimize the complexity of the search space. The result is an optimization of simulation parameters using an iterative scheme that aims to minimize the difference between experimentally measured count rates and simulated count rates across all tested collimator combinations.

This proposed methodology holds the potential to reveal previously unrecognized sources of intensity loss in the CG-2 beamline at HFIR and improve the accuracy of simulations, leading to enhanced understanding and performance of the beamline for various scientific applications.

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优化光线跟踪模拟，确认高通量同位素反应堆 GP-SANS 仪器的性能

高通量同位素反应堆（HFIR）的 CG-2 光束线在观测到的计数率与我们根据蒙特卡洛中子射线迹线模拟所预期的计数率之间存在明显差异。这些模拟预测的计数率始终比涉及不同仪器配置的四次独立实验运行中观测到的计数率高出约五倍。这种差异表明，某些因素造成了测量中的损失，而这些因素在模拟中没有得到充分考虑，特别是导向反射率或偏差。为了研究这些差异，我们采用了一种高维模拟参数方法，以了解这些损失。在模拟过程中，沿仪器的兴趣区域（ROI）组被分配给导轨部件的不同表面。这样，这些导轨部件的参数就可以作为一组参数进行更改，从而最大限度地降低搜索空间的复杂性。结果是使用迭代方案对模拟参数进行优化，目的是在所有测试的准直器组合中最大限度地减少实验测量计数率与模拟计数率之间的差异。这种方法有望揭示高频红外光谱仪 CG-2 光束线以前未认识到的强度损失源，并提高模拟的准确性，从而增强对光束线的了解，提高其在各种科学应用中的性能。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment 物理-光谱学

CiteScore

3.20

自引率

21.40%

发文量

787

审稿时长

1 months

期刊介绍： Section A of Nuclear Instruments and Methods in Physics Research publishes papers on design, manufacturing and performance of scientific instruments with an emphasis on large scale facilities. This includes the development of particle accelerators, ion sources, beam transport systems and target arrangements as well as the use of secondary phenomena such as synchrotron radiation and free electron lasers. It also includes all types of instrumentation for the detection and spectrometry of radiations from high energy processes and nuclear decays, as well as instrumentation for experiments at nuclear reactors. Specialized electronics for nuclear and other types of spectrometry as well as computerization of measurements and control systems in this area also find their place in the A section. Theoretical as well as experimental papers are accepted.