2025/12/22 by S. E. A. Orrigo, Orrigo, S. E. A., J. L. Tain +30
Physics and Astronomy · #Atomic and Subatomic Physics Research #Dark Matter and Cosmic Phenomena #Neutrino Physics Research #hep-ex #nucl-ex
paper · pdf · doi:10.48550/arxiv.2512.19857
published as Letter in Eur. Phys. J. C 86, 834 (2026) · 5 pages, 3 figures, 1 table
arxiv created 2026/07/29 · arxiv updated 2026/07/31
We report on the measurement of the ambient neutron flux and its energy distribution over a broad range of neutron energies, conducted in Hall A of the Canfranc Underground Laboratory using the High Efficiency Neutron Spectrometry Array (HENSA), with a total livetime of 248 days. In particular, we obtained a thermal neutron flux of 3.4(2) × 10-6 cm-2 s-1 and a total energy-integrated flux of 14.8(2) × 10-6 cm-2 s-1. This work represents the first long-term measurement of the ambient neutron flux that includes a full spectral characterization across a wide energy interval (from 10-4 eV to 20 MeV), performed in an underground laboratory to date. The results are relevant for rare-event search experiments located underground, ranging from nuclear astrophysics to astroparticle physics.