Neutron production by cosmic-ray muons at shallow depth

TL;DR

This study measures the neutron yield produced by cosmic-ray muons at a shallow depth of 32 meters water equivalent, providing data crucial for background understanding in underground experiments.

Contribution

It presents a new measurement of neutron yield at shallow depth using a Gd-loaded scintillator detector, with detailed modeling of neutron capture efficiency.

Findings

Neutron yield measured as (3.60 ± 0.09 ± 0.31) × 10^{-5} neutrons per muon and g/cm²

Results are consistent with previous measurements at similar depths

The study improves understanding of muon-induced neutron backgrounds

Abstract

The yield of neutrons produced by cosmic ray muons at a shallow depth of 32 meters of water equivalent has been measured. The Palo Verde neutrino detector, containing 11.3 tons of Gd loaded liquid scintillator and 3.5 tons of acrylic served as a target. The rate of one and two neutron captures was determined. Modeling the neutron capture efficiency allowed us to deduce the total yield of neutrons $ Y_{tot} = (3.60 \pm 0.09 \pm 0.31) \times 10^{-5}$ neutrons per muon and g/cm$^2$. This yield is consistent with previous measurements at similar depths.