Eur. Phys. J. A (2019) 55: 115
https://doi.org/10.1140/epja/i2019-12808-1

Special Article - New Tools and Techniques

Neutron energy spectrum measurement of the Back-n white neutron source at CSNS

¹ Institute of High Energy Physics, Chinese Academy of Sciences (CAS), 100049, Beijing, China
² Dongguan Neutron Science Center, 523803, Dongguan, China
³ Key Laboratory of Nuclear Data, China Institute of Atomic Energy, 102413, Beijing, China
⁴ State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, 230026, Hefei, China
⁵ Department of Modern Physics, University of Science and Technology of China, 230026, Hefei, China
⁶ State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, 100871, Beijing, China
⁷ Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, 621900, Mianyang, China
⁸ University of South China, 421001, Hengyang, China
⁹ Northwest Institute of Nuclear Technology, 710024, Xi’an, China
¹⁰ Department of Engineering and Applied Physics, University of Science and Technology of China, 230026, Hefei, China
¹¹ School of Physics, Beihang University, 100083, Beijing, China
¹² Xi’an Jiaotong University, 710049, Xi’an, China

^* e-mail: baojie_ciae@126.com

Received: 20 March 2019
Accepted: 17 June 2019
Published online: 24 July 2019

Abstract

China Spallation Neutron Source (CSNS) has been built and commissioned successfully in 2018 which is implemented by impinging 1.6 GeV protons onto a tungsten target with 25 Hz repetition frequency. An associated white neutron beam line exploiting the back-streaming neutrons, named Back-n, with a flight path of 55 m in endstation 1 (#ES1) and 76 m in endstation 2 (#ES2) was built mainly for nuclear data measurements. The Back-n beam line started running since the beginning of 2018 and the neutron energy spectrum was measured at the very beginning since it is an essential information for feasibility study and analysis of any measurement. In this paper, the measurement of the neutron energy spectrum of Back-n #ES2 is reported. The first result of the neutron flux from 1 eV to 100 MeV measured by a fission chamber based on the ²³⁵U(n, f) reaction is presented. The total neutron flux normalized to the proton beam power of 100 kW is neutrons/cm²/s. The results show a good agreement with that of the Monte Carlo simulation as well.