A new software implementation of the Oslo method with rigorous statistical uncertainty propagation

The Oslo method comprises a set of analysis techniques designed to extract nuclear level density and average γ-decay strength function from a set of excitation-energy tagged γ-ray spectra. Here we present a new software implementation of the entire Oslo method, called OMpy. We provide a summary of the theoretical basis and derive the essential equations used in the Oslo method. In addition to the functionality of the original analysis code, the new implementation includes novel components such as a rigorous method to propagate uncertainties throughout all steps of the Oslo method using a Monte Carlo approach. The resulting level density and γ-ray strength function have to be normalized to auxiliary data. The normalization is performed simultaneously for both quantities, thus preserving all correlations. The software is verified by the analysis of a synthetic spectrum and compared to the results of the previous implementation, the oslo-method-software.奥斯陆方法（Oslo method）是一套分析技术集，旨在从经激发能标记的γ射线能谱中提取原子核能级密度与平均γ衰变强度函数。本文提出了一套完整实现奥斯陆方法的全新软件，命名为OMpy。本文对奥斯陆方法的理论基础进行了总结，并推导了该方法所用的核心方程。相较于原版分析代码的功能，该全新实现新增了多项特性：例如采用蒙特卡洛（Monte Carlo）方法，对奥斯陆方法全流程中的不确定度开展严格传递的严谨方案。最终得到的能级密度与γ射线强度函数需借助辅助数据完成归一化，且归一化过程会同时针对这两个物理量进行，从而保留全部关联关系。本软件通过对人工合成能谱的分析完成验证，并与此前的实现版本oslo-method-software的计算结果进行了对比。