标题： 一种用于原位$γ$-射线光谱学的新FSA方法 显示英文标题

标题： A new FSA approach for in situ $γ$-ray spectroscopy

摘要： 对环境放射性监测的需求日益增加，这既来自科学界也来自社会。 这需要准确、可靠且快速响应的便携式辐射探测器。 由于技术的最新改进，使用碘化钠闪烁体的$\gamma$谱分析已被证明是用于现场测量以识别和定量确定$\gamma$射线发射放射性同位素的优秀工具，从而节省时间和成本。 无论是地质还是民用目的，不仅需要测量$^{40}$K、$^{238}$U 和$^{232}$Th，而且对确定人为元素如$^{137}$Cs 和$^{131}$I 的丰度也日益感兴趣，这些元素用于监测核事故或其他人类活动的影响。 全谱分析（FSA）方法被选用来分析$\gamma$谱。 非负最小二乘（NNLS）和能量校准调整首次在此方法中实现，以纠正与$\chi ^2$最小化相关的基本问题，这可能导致分析中出现伪影和非物理结果。 通过使用原位$\gamma$谱代替校准垫谱，开发了一种新的校准程序用于 FSA 方法。 最后，通过在托斯卡纳的 Ombrone 盆地的 80 个不同地点使用 10.16 厘米 x 10.16 厘米的碘化钠探测器获取$\gamma$谱，验证了新方法。 通过使用 HPGe 探测器对不同地点采集的土壤样品进行实验室测量，将 FSA 方法的结果进行了比较，显示两者之间有令人满意的一致性。 特别是，由于在原位测量中发现$^{137}$铯同位素不可忽略，因此将其纳入分析中。 显示英文摘要

摘要： An increasing demand of environmental radioactivity monitoring comes both from the scientific community and from the society. This requires accurate, reliable and fast response preferably from portable radiation detectors. Thanks to recent improvements in the technology, $\gamma$-spectroscopy with sodium iodide scintillators has been proved to be an excellent tool for in-situ measurements for the identification and quantitative determination of $\gamma$-ray emitting radioisotopes, reducing time and costs. Both for geological and civil purposes not only $^{40}$K, $^{238}$U, and $^{232}$Th have to be measured, but there is also a growing interest to determine the abundances of anthropic elements, like $^{137}$Cs and $^{131}$I, which are used to monitor the effect of nuclear accidents or other human activities. The Full Spectrum Analysis (FSA) approach has been chosen to analyze the $\gamma$-spectra. The Non Negative Least Square (NNLS) and the energy calibration adjustment have been implemented in this method for the first time in order to correct the intrinsic problem related with the $\chi ^2$ minimization which could lead to artifacts and non physical results in the analysis. A new calibration procedure has been developed for the FSA method by using in situ $\gamma$-spectra instead of calibration pad spectra. Finally, the new method has been validated by acquiring $\gamma$-spectra with a 10.16 cm x 10.16 cm sodium iodide detector in 80 different sites in the Ombrone basin, in Tuscany. The results from the FSA method have been compared with the laboratory measurements by using HPGe detectors on soil samples collected in the different sites, showing a satisfactory agreement between them. In particular, the $^{137}$Cs isotopes has been implemented in the analysis since it has been found not negligible during the in-situ measurements.