Vanderloo N, Cufari M, Russell L, Johnson T M, Vargas J, Foo B C, Buschmann B I, Dannhoff S G, DeVault A, Evans T E, Kunimune J H, Lawrence Y, Pearcy J A, Reichelt B L, Wink C W, Gatu Johnson M, Petrasso R D, Frenje J A, Li C K
Plasma Science and Fusion Center, MIT. Cambridge, Massachusetts 02139, USA.
Rev Sci Instrum. 2024 Sep 1;95(9). doi: 10.1063/5.0219547.
Image plates (IPs) are a quickly recoverable and reusable radiation detector often used to measure proton and x-ray fluence in laser-driven experiments. Recently, IPs have been used in a proton radiography detector stack on the OMEGA laser, a diagnostic historically implemented with CR-39, or radiochromic film. The IPs used in this and other diagnostics detect charged particles, neutrons, and x-rays indiscriminately. IPs detect radiation using a photo-stimulated luminescence (PSL) material, often phosphor, in which electrons are excited to metastable states by ionizing radiation. Protons at MeV energies deposit energy deeper into the IP compared with x rays below ∼20 keV due to the Bragg peak present for protons. This property is exploited to discriminate between radiation types. Doses of mono-energetic protons between 1.7 and 14 MeV are applied to IPs using the MIT linear electrostatic ion accelerator. This paper presents the results from consecutive scans of IPs irradiated with different proton energies. The PSL ratios between subsequent scans are shown to depend on proton energy, with higher energy protons having lower PSL ratios for each scan. This finding is separate from the known energy dependence in the absolute sensitivity of IPs. The results can be compared to complimentary work on x rays, showing a difference between protons and x rays, forging a path to discriminate between proton and x-ray fluence in mixed radiation environments.
影像板（IP）是一种可快速恢复且可重复使用的辐射探测器，常用于测量激光驱动实验中的质子和X射线注量。最近，IP已被用于欧米茄激光装置上的质子射线照相探测器堆栈中，该诊断方法在历史上一直使用CR - 39或放射变色胶片来实现。在此以及其他诊断中使用的IP会不加区分地探测带电粒子、中子和X射线。IP使用光激励发光（PSL）材料（通常是磷光体）来探测辐射，在这种材料中，电子通过电离辐射被激发到亚稳态。由于质子存在布拉格峰，与能量低于约20 keV的X射线相比，兆电子伏能量的质子在IP中沉积的能量更深。利用这一特性来区分不同类型的辐射。使用麻省理工学院线性静电离子加速器将能量在1.7至14 MeV之间的单能质子剂量施加到IP上。本文展示了用不同质子能量照射IP后的连续扫描结果。后续扫描之间的PSL比率显示取决于质子能量，对于每次扫描，能量较高的质子具有较低的PSL比率。这一发现与IP绝对灵敏度中已知的能量依赖性不同。该结果可与关于X射线的补充研究结果进行比较，显示出质子和X射线之间的差异，为在混合辐射环境中区分质子和X射线注量开辟了一条途径。
