Reflectivity quenching of ESR multilayer polymer film reflector in optically bonded scintillator arrays
Reflectivity quenching of ESR multilayer polymer film reflector in optically bonded scintillator arrays
复制标题
光学粘合闪烁体阵列中 ESR 多层聚合物膜反射器的反射率猝灭
DOI：
10.1016/j.nima.2017.01.051
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发表时间：
2017
影响因子：
1.4
通讯作者：
R. Lecomte
中科院分区：
文献类型：
--
作者：
Francis Loignon;C. Pepin;S. Charlebois;R. Lecomte
3M-ESR多层聚合物薄膜是一种广泛应用于闪烁探测器阵列的反射镜。正如数据手册中指定的，并通过在空气中的测量实验证实，它在所有入射角度的整个可见光光谱(400-1000 nm)上都具有高反射率(>；98%)。尽管有这些突出的特性，以前发现，在带有电子自旋共振反射器的粘合LYSO闪烁体阵列中，像素之间的光串扰可以高达∼30%-35%。这种无法解释的光串扰激发了对ESR光学性能的进一步研究。对模拟ESR反射器的多层膜结构的分析模拟表明，当薄膜两侧被折射率高于空气的材料包围时，薄膜对大角度入射光变得高度透明。蒙特卡罗模拟表明，在高宽高比的LYSO闪烁晶体中，相当一部分(∼为25-35%)的闪烁光子入射到这些泄漏角度。通过测量夹在闪烁晶体和光电探测器之间的ESR薄膜的闪烁光透过率，实验研究了薄膜的透明度。当两面涂覆有机硅时，通过反射器测量到高达30%的强光泄漏，从而阐明了键合阵列中光串扰的主要原因。使用定制设计的设置，允许在选定的掠入射角下照射粘合的ESR薄膜，在大于~60°的入射角下通过实验确认了反射器的透明度。意想不到的ESR膜透明度对于利用光共享方案的探测器阵列是有利的，但对于为单个像素读出而设计的闪烁体阵列是非常有害的。
The 3M-ESR multilayer polymer film is a widely used reflector in scintillation detector arrays. As specified in the datasheet and confirmed experimentally by measurements in air, it is highly reflective (> 98%) over the entire visible spectrum (400–1000 nm) for all angles of incidence. Despite these outstanding characteristics, it was previously found that light crosstalk between pixels in a bonded LYSO scintillator array with ESR reflector can be as high as∼ 30–35%. This unexplained light crosstalk motivated further investigation of ESR optical performance. Analytical simulation of a multilayer structure emulating the ESR reflector showed that the film becomes highly transparent to incident light at large angles when surrounded on both sides by materials of refractive index higher than air. Monte Carlo simulations indicate that a considerable fraction (∼ 25–35%) of scintillation photons are incident at these leaking angles in high aspect ratio LYSO scintillation crystals. The film transparency was investigated experimentally by measuring the scintillation light transmission through the ESR film sandwiched between a scintillation crystal and a photodetector with or without layers of silicone grease. Strong light leakage, up to nearly 30%, was measured through the reflector when coated on both sides with silicone, thus elucidating the major cause of light crosstalk in bonded arrays. The reflector transparency was confirmed experimentally for angles of incidence larger than~ 60° using a custom designed setup allowing illumination of the bonded ESR film at selected grazing angles. The unsuspected ESR film transparency can be beneficial for detector arrays exploiting light sharing schemes, but it is highly detrimental for scintillator arrays designed for individual pixel readout.