Shielding Experiments Under JASMIN Collaboration at Fermilab(III) - Measurement of High-Energy Neutrons Penetrating a Thick Iron Shield from the Antiproton Production Target by AU Activation Method

TL;DR

This study measures high-energy neutrons (>100 MeV) penetrating a thick iron shield at Fermilab using Au activation, providing data to improve neutron transport models at high-energy proton facilities.

Contribution

It demonstrates the effectiveness of the Au activation method for indirect measurement of high-energy neutrons and compares experimental data with theoretical calculations.

Findings

Au activation method successfully measures >100 MeV neutrons.

Measured production rates align with PHITS calculations.

Results aid in refining high-energy neutron transport models.

Abstract

In an antiproton production (Pbar) target station of the Fermi National Accelerator Laboratory (FNAL), the secondary particles produced by bombarding a target with 120-GeV protons are shielded by a thick iron shield. In order to obtain experimental data on high-energy neutron transport at more than 100-GeV-proton accelerator facilities, we indirectly measured more than 100-MeV neutrons at the outside of the iron shield at an angle of 50{\deg} in the Pbar target station. The measurement was performed by using the Au activation method coupled with a low-background {\gamma}-ray counting system. As an indicator for the neutron flux, we determined the production rates of 8 spallation nuclides (196-Au, 188-Pt, 189-Ir, 185-Os, 175-Hf, 173-Lu, 171-Lu, and 169-Yb) in the Au activation detector. The measured production rates were compared with the theoretical production rates calculated using PHITS. We proved that the Au activation method can serve as a powerful tool for indirect measurements of more than 100-MeV neutrons that play a vital role in neutron transport. These results will be important for clarifying the problems in theoretical calculations of high-energy neutron transport.