Cosmogenic background study for a 100Mo-based bolometric demonstration experiment at China JinPing underground Laboratory

TL;DR

This study uses simulations to evaluate cosmogenic backgrounds in a $^{100}$Mo bolometric experiment at CJPL, finding low residual backgrounds after underground cooling, supporting its feasibility for neutrinoless double-beta decay searches.

Contribution

It provides a detailed simulation-based assessment of cosmogenic radionuclide production and background levels for a $^{100}$Mo bolometric $0 uetaeta$ experiment at CJPL, including residual background estimates after underground cooling.

Findings

Residual background after one year underground cooling is very low.

Cosmogenic activation of copper and crystals is negligible underground.

Simulations show the experiment's background levels are suitable for $0 uetaeta$ search.

Abstract

We perform simulation study for a 10-kg $^{100}$Mo-based bolometeric demonstration experiment for neutrinoless double-beta decay ($0\nu\beta\beta$) search at China JinPing underground Laboratory (CJPL). Cosmogenic production of radionuclides in $^{100}$Mo-enriched lithium molybdate crystals and copper components of the detector system are studied using Geant4 toolkit based on the simulated cosmic ray data from the CRY library. Background energy spectra of the cosmogenic radionuclides including $^{56}$Co, $^{82}$Rb and $^{88}$Y which are harmful for the $^{100}$Mo-based $0\nu\beta\beta$ experiment are investigated. We then evaluate the total cosmogenic background level in the $^{100}$Mo $0\nu\beta\beta$ search energy region of interest (ROI) for the demonstration experiment. After one year of cooling down underground, the residual background contribution is found to be 1.8$\times$10$^{-6}$ cts/kg/keV/yr and 3.3$\times$10$^{-4}$ cts/kg/keV/yr from crystals and copper components, respectively. Furthermore, underground cosmogenic activation of copper and lithium molybdate crystal is calculated based on the simulation spectra of neutron and proton in CJPL. The underground cosmogenic background is found to be negligible in the ROI.