Study on collimation and shielding of the back-streaming neutrons at the CSNS target

Abstract

The back-streaming neutrons from the spallation target at CSNS are very intense, and can pose serious damage problems for the devices in the accelerator-target interface region. To tackle the problems, a possible scheme for this region was studied, namely a specially designed optics for the proton beam line produces two beam waists, and two collimators are placed at the two waist positions to maximize the collimation effect of the back-streaming neutrons. Detailed Monte Carlo simulations with the beams in the two different CSNS phases show the effectiveness of the collimation system, and the radiation dose rate decreases largely in the interface section. This can ensure the use of epoxy coils for the last magnets and other devices in the beam transport line with reasonable lifetimes, e.g. thirty years. The design philosophy for such an accelerator-target interface region can also be applicable to other high-power proton beam applications.

Measurement of the neutron energy spectrum of Back-n #ES1 at CSNS

“…It is also capable of supporting multiple platforms, such as the application of high energy protons, muon beam and white neutron beam [6]. A beam line exploiting the backstreaming neutrons, named Back-n, is built mainly for the nuclear data measurements and started running simultaneously with CSNS in 2018 [7][8][9][10]. The neutron energy spectrum of Back-n is characterized since it is of great im- * e-mail: baojie_ciae@126.com portance for feasibility study and analysis for the measurements.…”

Back-n white neutron facility for nuclear data measurements at CSNS

“…Earlier studies show that the back-streaming neutrons from the spallation target is very much suitable to be exploited as a white neutron source for nuclear data measurements [4][5][6][7][8]. With rapid development of nuclear energy in China, especially for next-generation reactors, very strong and eminent demand for much enhanced nuclear database has been increasing.…”

Short-bunch extraction in a rapid cycling synchrotron

“…The backstreaming neutrons from the spallation target of CSNS are very strong and harmful to the devices in the proton beam transport line if they are not well treated [7]. However, the studies found that the neutron beam has excellent properties in energy spectrum and time structure, and it has been proposed to build a white neutron beam line or white neutron source (WNS) for nuclear data measurements [8], which is now under construction.…”