论文标题

单核子散射的不确定性量化现象学光学电位

Uncertainty-quantified phenomenological optical potentials for single-nucleon scattering

论文作者

Pruitt, C. D., Escher, J. E., Rahman, R.

论文摘要

光学模型电位(OMP)在核反应计算中继续发挥关键作用。但是,现象学在广泛使用中的不确定性(对数据训练的任何参数模型所固有的)尚未充分表征,并且对OPM的下游使用者的影响尚不清楚。在这里,我们使用Markov-Chain Monte Carlo进行参数推断,为两个代表性的全球OMP分配了良好的不确定性,即Koning-Delaroche和Chapel Hill '89。通过将这些OMP的规范版本与最初用于限制它们的实验数据进行比较,我们表明缺乏异常排斥反应以及对实验不确定性的系统低估如何有助于最佳拟合参数值的偏见和过度启发。这些OMP的更新,不确定性的版本解决了这些问题,并为潜在参数提供了完整的协方差信息。从我们的团结中产生的散射预测表明,针对实验数据的原始培训语料库,以及与新的“测试”语料库相对于包括过去二十年收集的许多实验单核子散射数据的新的“测试”语料库的性能提高。最后,我们将不确定性定量的OMP应用于与应用相关的横截面的两个案例研究。我们得出的结论是,对于包括OMP不确定性在内的许多常见应用,应该成为标准实践。为了促进它们的立即使用,将我们更新的OMP和相关工具的数字版本作为补充材料包括在内。

Optical-model potentials (OMPs) continue to play a key role in nuclear reaction calculations. However, the uncertainty of phenomenological OMPs in widespread use -- inherent to any parametric model trained on data -- has not been fully characterized, and its impact on downstream users of OMPs remains unclear. Here we assign well-calibrated uncertainties for two representative global OMPs, those of Koning-Delaroche and Chapel Hill '89, using Markov-Chain Monte Carlo for parameter inference. By comparing the canonical versions of these OMPs against the experimental data originally used to constrain them, we show how a lack of outlier rejection and a systematic underestimation of experimental uncertainties contributes to bias of, and overconfidence in, best-fit parameter values. Our updated, uncertainty-quantified versions of these OMPs address these issues and yield complete covariance information for potential parameters. Scattering predictions generated from our ensembles show improved performance both against the original training corpora of experimental data and against a new "test" corpus comprising many of the experimental single-nucleon scattering data collected over the last twenty years. Finally, we apply our uncertainty-quantified OMPs to two case studies of application-relevant cross sections. We conclude that, for many common applications of OMPs, including OMP uncertainty should become standard practice. To facilitate their immediate use, digital versions of our updated OMPs and related tools for forward uncertainty propagation are included as Supplementary Material.

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