A novel method for monitoring proton beam spot using back-streaming secondary neutrons from the target

TL;DR

This paper introduces a novel, indirect, and flexible beam monitoring technique using back-streaming secondary neutrons and pinhole imaging to visualize high-power proton beam spots at a distance, enhancing stability and safety.

Contribution

It proposes a new neutron-based imaging method for proton beam monitoring that allows remote, fast, and adjustable visualization of the beam spot, improving upon existing direct measurement techniques.

Findings

Simulation results confirm the method's ability to accurately restore the proton beam spot.

The method effectively operates at distances of tens of meters from the target.

Adjustable parameters enable optimization for different detection system demands.

Abstract

The power of the proton beam of a high-power spallation neutron source generally ranges from 100 kW to several MW. The distribution of the power density of the beam on the target is critical for the stable operation of the high-power spallation target. This study proposes a beam monitoring method that involves restoring the image of a high-power proton beam spot on a target based on the principle of pinhole imaging by using the back-streaming of secondary neutrons from the spallation target. Fast and indirect imaging of the beam spot can be achieved at a distance of tens of meters from the target. The proposed method of beam monitoring can flexibly adjust the size of the pinhole and the measurement distance to control the intensity of flux of the secondary neutrons according to the demands of the detection system, which is far from the high-radiation target area. The results of simulations showed that the proposed method can be used to restore the beam spot of the incident proton by using the point response function and images of the secondary neutrons. Based on the target and the Back-n beamline in the CSNS, the effectiveness of this method has also been confirmed.