Transfer Reaction Spectroscopy with Neutrinoless Double Beta Decay Candidate Nuclei

这个项目是用转移反应研究中微子双β衰变候选核的核子占位率。镉-116是通过无中微子双β衰变衰变的候选核。它衰变为tin-116。如果通过某种实验观察到这个原子核的无中微子衰变，就有可能计算出中微子的质量——假设衰变的矩阵元素是已知的。由于这是唯一出现该矩阵元素的过程，因此必须从理论上进行计算。由于不存在探测相同矩阵元素的其他过程，因此计算的有效性值得怀疑。核子占位提供了一种可观察的东西，通过它可以检验计算矩阵元素所涉及的模型。中子转移反应光谱是测量能量、角动量和感兴趣的核态截面的一种方法。一束光粒子撞击正在研究的同位素组成的目标。对于这些束粒子中的一些，中子在束和目标之间转移。对于这些反应，可以探测到残核态的能量和角动量。通过测量填充这些状态的微分截面，可以提取出单粒子强度——一个与核子占用率相关的量。双β衰变的子代元素锡-116已经这样做了，但母体元素镉-116却没有。项目的第一部分将集中于这些度量。项目的另一面根植于数据科学。目前，该部门使用一个名为gf3的程序来拟合光谱。这个程序半手动计算拟合，提示用户找到感兴趣的区域和该区域的峰值位置，然后将倾斜的高斯函数拟合到峰值上。然后，它在用于运行程序的终端中以文本形式输出有关峰值的信息。自动拟合会更有效，输出一个拟合图和itschi-squared，以及一个峰值位置和其他参数的输出文件。这个项目的第二部分将着眼于制作一个可以做到这一点的程序。对传递反应模型中输入参数选择的适用性进行更完整的统计分析也将进行。

This project is a study of the nucleon occupancies of neutrinoless double beta decay candidatenuclei using transfer reactions.Cadmium-116 is a candidate nucleus to decay via neutrinoless double beta decay. It decays totin-116. Should neutrinoless decay in this nucleus be observed by some experiment, it would bepossible to calculate the mass of the neutrino - given the matrix element of the decay is known.Since this is the only process in which this matrix element appears, it must be calculatedtheoretically. As no other process exists which probes the same matrix element then the validityof the calculations is questionable. Nucleon occupancies provide an observable through whichthe models involved in calculating matrix elements can be tested.Neutron transfer reaction spectroscopy is one method of measuring the energies, angularmomentum, and cross sections of nuclear states of interest. A beam of light particles impinges ofa target made of the isotope being studied. For some of these beam particles, a neutron istransferred between the beam and the target. For these reactions, the energies and angularmomenta of states in the residual nucleus can be probed. Through a measurement of thedifferential cross sections for populating these states the single-particle strengths can be extracted- a quantity related to the nucleon occupancies. This has been done for tin-116, the daughter indouble beta decay but not for cadmium-116, the parent. The first part of the project will focus onthese measurements.The other side of the project is rooted in data science. Currently, the department uses a programcalled gf3 to fit spectra. This program calculates fits semi-manually, prompting the user to find aregion of interest and peak positions in that region, then fits skewed Gaussian functions to thepeaks. It then outputs information about the peaks in text in the terminal used to run the program.It would be much more efficient for an automatic fit, with an output of a graph of the fit and itschi-squared, and an output file of peak positions and other parameters. The second part of thisproject will look to producing a program that can do this. A more complete statistical analysis ofthe suitability of choice of input parameters in to transfer reaction modelling will also be carriedout.