Evaluation of the WIPP site for the supernova neutrino burst observatory

Abstract

Measurements of the neutron background in a potential underground site for the Supernova Neutrino Burst Observatory (SNBO) have been made. The SNBO will ultimately be capable of detecting μ and τ neutrinos from a supernova. Furthermore, masses of the μ and τ neutrinos might be measurable in the range of 10–50 eV. SNBO operates by detecting the neutrons caused by interaction of the supernova neutrinos with rock. It will consist of order ten thousand neutron detectors located in an underground environment having a very low intrinsic radiation level. The limit to the size, hence sensitivity, of SNBO is thus the neutron signal-to-noise ratio, which depends on the neutron background in the environment of SNBO. Thus we have made neutron background measurements at the Department of Energy Waste Isolation Pilot Plant (WIPP) located near Carlsbad, NM. The value of the ambient neutron flux we determined, 332 ± 148 neutrons m −2d −1, shows that the background levels in this facility are sufficiently low to warrant construction of a galactic supernova neutrino detector.