Measurement of fast neutron background in the Gran Sasso underground laboratory using a geyser-concept bubble-chamber

A measurement of the fast neutron background in the Gran Sasso underground laboratory has been performed by the MOSCAB thermodynamic bubble chamber, a neutron detector which identifies fast neutrons passing through the metastable fluid by scattering ions. The result of this measure- ment confirms the results previously obtained using detectors based on totally different techniques, thus corroborating the previous results in terms of both integral intensity and spec- tral characteristics, at least in the energy region where the current measurement technique is sensitive.