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 Ytot=(3.60±0.09±0.31)×10−5 neutrons per muon and g/cm2. This yield is consistent with previous measurements at similar depths.
@article{arxiv.hep-ex/0006014,
title = {Neutron production by cosmic-ray muons at shallow depth},
author = {F. Boehm and J. Busenitz and B. Cook and G. Gratta and H. Henrikson and J. Kornis D. Lawrence and K. B. Lee and K. McKinny and L. Miller and V. Novikov and A. Piepke and B. Ritchie and D. Tracy and P. Vogel and Y-F. Wang and J. Wolf},
journal= {arXiv preprint arXiv:hep-ex/0006014},
year = {2009}
}