Transfer Reaction Spectroscopy with Neutrinoless Double Beta Decay Candidate Nuclei

本项目是利用转移反应研究无中微子双β衰变候选核的核子占有率，Cd-116是一个经过无中微子双β衰变的候选核。它衰变到锡-116。如果通过实验观察到这个核中的无中微子衰变，那么在已知衰变的矩阵元的情况下，就有可能计算出中微子的质量。因为这是唯一出现矩阵元的过程，所以必须从理论上计算。由于没有其他的过程存在，探测相同的矩阵元素，那么计算的有效性是值得怀疑的。核子占据率提供了一个可观测量，通过它可以检验计算矩阵元的模型。中子转移反应谱是测量感兴趣的核子态的能量、角动量和截面的一种方法。一束光粒子撞击由正在研究的同位素制成的靶。对于这些束粒子中的一些，中子在束和靶之间转移。对于这些反应，可以探测剩余核中的态的能量和角动量。通过测量填充这些状态的微分截面，可以提取单粒子强度--一个与核子占有率相关的量。这已经对双β衰变的子体锡-116进行了研究，但对母体镉-116却没有。该项目的第一部分将专注于这些测量。该项目的另一面植根于数据科学。目前，该部门使用一个名为gf 3的程序来拟合光谱。该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中的峰位置，然后将偏高斯函数拟合到峰。然后，它会在运行程序的终端中以文本形式输出有关峰的信息。对于自动拟合来说，它会更有效，输出拟合和它的平方的图形，以及峰位置和其他参数的输出文件。该项目的第二部分将着眼于生产一个程序，可以做到这一点。还将对转移反应模型中输入参数选择的适用性进行更全面的统计分析。

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.