Neutron background measurements at China Jinping underground laboratory with a Bonner Multi-sphere Spectrometer

TL;DR

This study measured the neutron background spectrum at China Jinping underground laboratory using a Bonner multi-sphere spectrometer, providing detailed flux data from thermal to fast neutrons for underground physics experiments.

Contribution

First measurement of neutron background spectrum at China Jinping underground laboratory using a Bonner spectrometer with validation and correction procedures.

Findings

Neutron flux is (2.69 +/- 1.02) x 10^-5 cm^-2 s^-1

Energy distribution of neutrons was successfully obtained

Background from detector steel was estimated and corrected

Abstract

The neutron background spectrum from thermal neutron to 20 MeV fast neutron was measured at the first experimental hall of China Jinping underground laboratory with a Bonner multi-sphere spectrometer. The measurement system was validated by a Cf252 source and inconformity was corrected. Due to micro charge discharge, the dataset was screened and background from the steel of the detectors was estimated by MC simulation. Based on genetic algorithm we obtained the energy distribution of the neutron and the total flux of neutron was (2.69 +/-1.02) *10^-5 cm^-2s^-1