Experiments towards a neutron target for measurements in inverse kinematics

TL;DR

This study tests the feasibility of creating a neutron target using moderated spallation neutrons within a graphite cube, providing experimental flux distribution data to support future inverse kinematics reaction measurements.

Contribution

It presents experimental neutron flux measurements in a graphite moderator, validating simulation models and informing the development of a neutron target for nuclear physics experiments.

Findings

Measured neutron flux distributions agree with simulations for the full cube.

Discrepancies observed in the half cube setup.

Results support upcoming neutron target proof-of-principle tests.

Abstract

Neutron-induced reactions play an important role in fundamental nuclear physics, nuclear astrophysics, and applications. In the case of reactions on rare isotopes, there are limited options for direct experimental measurements. The Neutron Target Demonstrator project at Los Alamos National Laboratory seeks to test the feasibility of moderating spallation neutrons within a 1~m$^3$ graphite cube to create a standing neutron target for neutron-induced reaction measurements in inverse kinematics. This paper presents the results of experimental neutron flux distribution tests using neutron sources (ranging from 1~keV to 50~MeV) created by accelerators at the University of Notre Dame and Texas A\&M University. Measurements were made with both the full graphite cube as well as a ''half cube'' setup in which half of the graphite cube was removed. The measured distributions agree with simulated distributions in the case of the full cube moderator, although there remain discrepancies in certain cases for the half cube moderator. The results shown here will provide useful information for an upcoming experimental campaign to test the neutron target proof-of-principle.