Experimental setup and procedure for the measurement of the 7Be(n,{\alpha}){\alpha} reaction at n_TOF

TL;DR

This paper presents a new experimental setup at CERN's n_TOF facility for measuring the 7Be(n,α) reaction cross-section, addressing previous measurement challenges and enabling studies of other difficult reactions.

Contribution

It introduces a novel detection apparatus and procedure for measuring the 7Be(n,α) reaction cross-section at n_TOF, overcoming past experimental limitations.

Findings

Successful detection of the 7Be(n,α) reaction signal amidst high background

Demonstration of the setup's capability to measure reactions on radioactive targets

Potential applicability to other challenging neutron-induced reactions

Abstract

The newly built second experimental area EAR2 of the n_TOF spallation neutron source at CERN allows to perform (n, charged particles) experiments on short-lived highly radioactive targets. This paper describes a detection apparatus and the experimental procedure for the determination of the cross-section of the 7Be(n,{\alpha}) reaction, which represents one of the focal points toward the solution of the cosmological Lithium abundance problem, and whose only measurement, at thermal energy, dates back to 1963. The apparently unsurmountable experimental difficulties stemming from the huge 7Be {\gamma}-activity, along with the lack of a suitable neutron beam facility, had so far prevented further measurements. The detection system is subject to considerable radiation damage, but is capable of disentangling the rare reaction signals from the very high background. This newly developed setup could likely be useful also to study other challenging reactions requiring the detectors to be installed directly in the neutron beam.