Neutron beam line design of a white neutron source at CSNS

Hantao Jing,Liying Zhang,Jie Ren,Pengcheng Wang,Xiangqi Wang,Hongqing Tang,Yongji Yu,Xichao Ruan,Qiang Li,Changjun Ning,Jingyu Tang

doi:10.1051/epjconf/201714603029

Abstract

China Spallation Neutron Source (CSNS), which is under construction, is a large scientific facility dedicated mainly for multi-disciplinary research on material characterization using neutron scattering techniques. The CSNS Phase-I accelerator will deliver a proton beam with an energy of 1.6 GeV and a pulse repetition rate of 25 Hz to a tungsten target, and the beam power is 100 kW. A white neutron source using the back-streaming neutrons through the incoming proton beam channel was proposed and is under construction. The back-streaming neutrons which are very intense and have good time structure are very suitable for nuclear data measurements. The white neutron source includes an 80-m neutron beam line, two experimental halls, and also six different types of spectrometers. The physics design of the beam line is presented in this paper, which includes beam optics and beam characterization simulations, with the emphasis on obtaining extremely low background. The first-batch experiments on nuclear data measurements are expected to be conducted in late 2017.

Highlights

China Spallation Neutron Source (CSNS) is a large scientific facility dedicated mainly for multidisciplinary research on material characterization using neutron scattering techniques [1, 2]
The back-streaming neutrons that are modestly moderated by the cooling water passing through the target slices have a very wide energy spectrum and a good time structure, and they are very suitable for nuclear data measurements
The back-streaming White Neutron Source (Back-n) at CSNS includes an 80-m neutron beam line and two experimental halls

Summary

Introduction

China Spallation Neutron Source (CSNS) is a large scientific facility dedicated mainly for multidisciplinary research on material characterization using neutron scattering techniques [1, 2]. The CSNS Phase-I, as shown, is under construction and expected to be completed in early 2018. The CSNS accelerator complex is designed to deliver the proton beam with an energy of 1.6 GeV and a pulse repetition rate of 25 Hz to a tungsten target, and the beam power at Phase-I is 100 kW. The beam power will be upgraded to 500 kW at Phase-II. A white neutron source using the back-streaming neutrons through the incoming proton beam channel was proposed and is under construction [3, 4]. The back-streaming neutrons that are modestly moderated by the cooling water passing through the target slices have a very wide energy spectrum (so-called white neutrons) and a good time structure, and they are very suitable for nuclear data measurements

Layout of back-streaming white neutron source

Neutron energy spectrum and time resolution

Experimental backgrounds

Radiation protection

Findings

Conclusions and status