Measurements of the neutron background for the Colorado Underground Research Institute (CURIE)
Abstract
We present the first direct measurements of the neutron background at the Colorado Underground Research Institute (CURIE), a shallow-underground facility with an effective overburden of approximately $400$~m.w.e.\ in the Edgar Experimental Mine in Idaho Springs, Colorado. The radiogenic and muon-induced components were characterized in the Subatomic Particle Hideout. The radiogenic component was measured with a custom Bonner Cylinder Spectrometer comprising a 3He proportional counter and six cylindrical high-density polyethylene moderators. Its response functions were simulated in \textsc{geant4}, empirically calibrated using a 239Pu-9Be source and the shadow-cone method, and then corrected to account for the approximately isotropic underground field. Unfolding the measured count rates gives a total local scalar neutron flux, dominated by radiogenic production, for En≲SI10MeV of (2.51±0.58stat±0.39sys)×10−5~\si{\per\square\centi\meter\per\second}. The muon-induced component was measured with a BC-501A organic liquid scintillator operated for \SI{1431}{\hour}. Pulse shape discrimination identified 55~±~7 neutron candidates. Using the simulated detector response, these counts yield an integral muon-induced neutron flux at the rock--cavern boundary above \SI{10.5}{\MeV} of (2.09±0.29stat +0.79−0.53sys)×10−7~\si{\per\square\centi\meter\per\second}. This flux uses the first-entry, boundary-area normalization of a previous CURIE simulation study. Its central value is approximately \SI{12}{\percent} higher than the site-specific prediction but is consistent within the reported uncertainties. Together, these measurements characterize the radiogenic and high-energy cosmogenic neutron environments at CURIE and provide quantitative input for planning future low-background experiments at the facility.
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BibTeX
@misc{keblbeck2026measurements,
title = {{Measurements of the neutron background for the Colorado Underground Research Institute (CURIE)}},
author = {Dakota K. Keblbeck and Uwe Greife and Eric Mayotte and Wouter Van De Pontseele and Kyle G. Leach},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31856},
eprint = {2610.31856},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31856},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Measurements of the neutron background for the Colorado Underground Research Institute (CURIE)
AU - Dakota K. Keblbeck
AU - Uwe Greife
AU - Eric Mayotte
AU - Wouter Van De Pontseele
AU - Kyle G. Leach
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31856
UR - https://arxiv.org/abs/2610.31856
AB - We present the first direct measurements of the neutron background at the Colorado Underground Research Institute (CURIE), a shallow-underground facility with an effective overburden of approximately $400$~m.w.e.\ in the Edgar Experimental Mine in Idaho Springs, Colorado. The radiogenic and muon-induced components were characterized in the Subatomic Particle Hideout. The radiogenic component was measured with a custom Bonner Cylinder Spectrometer comprising a ^3He proportional counter and six cylindrical high-density polyethylene moderators. Its response functions were simulated in \textsc{geant4}, empirically calibrated using a ^239Pu-^9Be source and the shadow-cone method, and then corrected to account for the approximately isotropic underground field. Unfolding the measured count rates gives a total local scalar neutron flux, dominated by radiogenic production, for E_n≲SI10MeV of (2.51±0.58_stat±0.39_sys)×10^−5~\si{\per\square\centi\meter\per\second}. The muon-induced component was measured with a BC-501A organic liquid scintillator operated for \SI{1431}{\hour}. Pulse shape discrimination identified 55~±~7 neutron candidates. Using the simulated detector response, these counts yield an integral muon-induced neutron flux at the rock--cavern boundary above \SI{10.5}{\MeV} of (2.09±0.29_stat ^+0.79_−0.53_sys)×10^−7~\si{\per\square\centi\meter\per\second}. This flux uses the first-entry, boundary-area normalization of a previous CURIE simulation study. Its central value is approximately \SI{12}{\percent} higher than the site-specific prediction but is consistent within the reported uncertainties. Together, these measurements characterize the radiogenic and high-energy cosmogenic neutron environments at CURIE and provide quantitative input for planning future low-background experiments at the facility.
ER -