# Measurements of the Total Cross section for Thermal Neutrons at PNS

## TL;DR

This paper reports the development of a pulsed neutron source using a LINAC and time-of-flight technique to measure the total cross section of thermal neutrons, specifically for natural beryllium, at the Shanghai Institute of Applied Physics.

## Contribution

It introduces a new photoneutron source (PNS) with digital signal processing for neutron and gamma-ray discrimination, and provides experimental data for beryllium's neutron cross section in the thermal range.

## Key findings

- Measured neutron total cross sections of beryllium from 0.007 to 0.1 eV.
- Compared results with existing data and response functions.
- Validated the PNS and TOF method for nuclear data acquisition.

## Abstract

In order to measure the total cross section for thermal neutrons, a photoneutron source (PNS, phase 1) has been developed for the acquisition of nuclear data for the Thorium Molten Salt Reactor (TMSR) at the Shanghai Institute of Applied Physics (SINAP). PNS is an electron LINAC pulsed neutron facility that uses the time-of-flight (TOF) technique. It records the neutron TOF and identifies neutrons and $\gamma$-rays by using a digital signal processing technique. The background is obtained by using a combination of employing 12.8 cm boron-loaded polyethylene(PEB) (5$\%$ w.t.) to block the flight path and Monte Carlo methods. The neutron total cross sections of natural beryllium are measured in the neutron energy region from 0.007 to 0.1 eV. The present measurement result is compared with the fold Harvey data with the response function of PNS.