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Nanodosimetry of light ions in targets of different size
Radiation Physics and Chemistry ( IF 2.9 ) Pub Date : 2020-07-01 , DOI: 10.1016/j.radphyschem.2020.108806
A. Selva , P. Colautti , V. Conte

Abstract Nanodosimetry measures the frequency distribution of the number of ionizations produced by primary particles in target volumes of nanometric size. At the Legnaro National Laboratories of INFN, a large measurement campaign was carried out with the Startrack nanodosimetric counter, which showed a consistent characterization of the ionization yield produced by different primary particles when the counter is filled at the design gas pressure of 300 Pa, corresponding to a mass thickness of 2.0 μg/cm2, i.e. about 20 nm at unit density. In order to investigate the operative limits of the Startrack counter and analyse the stochastics of the ionization yield also in targets of other sizes, new measurements were carried out at lower gas pressure. A first set of measurement was carried out with different primary ions at pressures of 200 Pa and 170 Pa, corresponding to a site size in mass per area of 1.4 μg/cm2 and 1.1 μg/cm2, respectively. A second set of measurements was carried out with low-energy lithium ions, varying the pressure in the range 150–300 Pa, i.e. down to a site size of 1.0 μg/cm2 (10 nm at unit density). The measured ionization cluster-size distributions were compared with Monte Carlo simulations performed with the MC-Startrack track structure code, in order to obtain a first estimation of the decrease in detection efficiency with decreasing gas pressure. The new results and their consistency with previous measurements are presented and discussed in this paper.

中文翻译:

不同尺寸目标中轻离子的纳米剂量学

摘要 纳米剂量测定法测量由初级粒子在纳米尺寸的目标体积中产生的电离次数的频率分布。在 INFN 的莱格纳罗国家实验室,使用 Startrack 纳米剂量计数器进行了一次大型测量活动,结果表明,当计数器在 300 Pa 的设计气压下充满时,不同初级粒子产生的电离产率具有一致的表征,相应的至 2.0 μg/cm2 的质量厚度,即单位密度下约 20 nm。为了研究 Startrack 计数器的操作限制并分析其他尺寸目标的电离产率的随机性,在较低的气压下进行了新的测量。使用不同的初级离子在 200 Pa 和 170 Pa 的压力下进行第一组测量,对应于单位面积质量的位点大小分别为 1.4 μg/cm2 和 1.1 μg/cm2。第二组测量是用低能锂离子进行的,在 150-300 Pa 的范围内改变压力,即下降到 1.0 μg/cm2(单位密度为 10 nm)的位点尺寸。将测量的电离簇大小分布与使用 MC-Startrack 轨道结构代码执行的蒙特卡罗模拟进行比较,以获得对检测效率随气压降低而降低的初步估计。本文介绍并讨论了新结果及其与以前测量结果的一致性。第二组测量是用低能锂离子进行的,在 150-300 Pa 的范围内改变压力,即下降到 1.0 μg/cm2(单位密度为 10 nm)的位点尺寸。将测量的电离簇大小分布与使用 MC-Startrack 轨道结构代码执行的蒙特卡罗模拟进行比较,以获得对检测效率随气压降低而降低的初步估计。本文介绍并讨论了新结果及其与以前测量结果的一致性。第二组测量是用低能锂离子进行的,在 150-300 Pa 的范围内改变压力,即下降到 1.0 μg/cm2(单位密度为 10 nm)的位点尺寸。将测量的电离簇大小分布与使用 MC-Startrack 轨道结构代码执行的蒙特卡罗模拟进行比较,以获得对检测效率随气压降低而降低的初步估计。本文介绍并讨论了新结果及其与以前测量结果的一致性。为了获得检测效率随气压降低而降低的初步估计。本文介绍并讨论了新结果及其与以前测量结果的一致性。为了获得检测效率随气压降低而降低的初步估计。本文介绍并讨论了新结果及其与以前测量结果的一致性。
更新日期:2020-07-01
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