The energy distribution of the neutron background was measured for the first time at Hall A
of the Canfranc Underground Laboratory. For this purpose we used a novel approach based
on the combination of the information obtained with six large high-pressure 3He proportional
counters embedded in individual polyethylene blocks of different size. In this way not only
the integral value but also the flux distribution as a function of neutron energy was
determined in the range from 1eV to 10MeV. This information is of importance because …