Improvement of Pulse Shape Discrimination Analysis for Dark Matter Search with a NaI(Tl) Crystal

by Jooyoung Lee (Ph.D Candidate)

Thursday May 13, 2021, 3:00 PM → 4:00 PM Asia/Seoul

216-1호 (제1과학관)

The COSINE-100 experiment has been established to reproduce the dark matter annual modulation signature in the range of 2-6 keVee energy region as reported by DAMA/LIBRA. The NaI(Tl) scintillation crystal was selected to detect nuclear recoil signals induced by the weakly interacting massive particle (WIMP) which is one of the most promising dark matter candidate. The WIMPs are expected to interact with sodium and iodine nuclei. We are expecting that pulse shape discrimination (PSD) will separate the neutron- and g-induced events. In order to search the NaI(Tl) response to neutron recoil and g recoil events, the neutron generator and AmBe radioactive source are used for this study. The conventional PSD parameter, meantime, is used for this analysis and the new parameter, bunch time summation (BTS) is developed to improve the separation power. The separation power is determined by the quality factor (QF) that has a correlation with the sensitivity for the WIMP detection. The machine learning is implemented to enhance the QF using two PSD parameters simultaneously. Finally, I have found that the BTS with machine learning analysis elevates the discrimination power. The estimated QF shows a better PSD power than that of the previous measurement by factor of two times.

Thesis Advisor: Prof. Hongjoo Kim

• URI http://www.dcollection.net/handler/knu/000000100048
• UCI I804:22001-000000100048