A New Beam Monitor at NFS/SPIRAL2 Based on Position-Sensitive PPACs Detecting Fission Fragments from ${}^{238}$U$(n,f)$

TL;DR

This paper introduces a novel neutron beam monitoring system at NFS/SPIRAL2 using position-sensitive PPACs to detect fission fragments from uranium targets, enabling real-time flux and profile measurements during high-intensity neutron experiments.

Contribution

The paper presents a new in-beam neutron monitoring setup based on position-sensitive PPACs that operates simultaneously with other experiments at NFS, providing real-time flux and profile data.

Findings

Successful detection of fission fragments in coincidence from ${}^{238}$U targets.

First measurements of neutron flux and beam profile at NFS using the new setup.

High transparency allows concurrent operation with other experiments.

Abstract

A new experimental setup has been installed at the Time-Of-Flight area of the Neutrons For Science facility (NFS) at GANIL/SPIRAL2 for neutron beam monitoring. This setup consists of an array of Position-Sensitive Parallel-Plate Avalanche Counters (PS-PPACs) that detects both fission fragments in coincidence from secondary neutron-induced fission reactions in several ${}^{238}$U targets. The neutron energy is determined on an event-by-event basis using the Time-of-Flight method, and the reaction point within the U targets is reconstructed, enabling the measurement of the neutron beam flux and beam profile. The high transparency of the setup allows it to operate in parallel with other experiments running at NFS, thus providing an in-beam monitor of the neutron intensity. In this work, we report on the characteristics of this new setup, its operating principle, and the first results obtained using the high-intensity white-spectrum neutron beam at NFS. This beam is produced via reactions between a primary 40-MeV deuteron beam, accelerated in the SPIRAL2 LINAC, and a 8 mm-thick rotating beryllium converter target.