Effective exploitation of a geyser bubble-chamber equipment as a background-free fast neutron detector

Abstract

The MOSCAB equipment, a geyser-concept bubble-chamber originally thought for the search of dark matter in the form of WIMPs, is employed for the detection of fast neutrons. Once the background-free operating conditions are determined such that the detector is sensitive only to neutrons, which occurs when the neutron energy threshold required for nucleation is higher than approximately 2.5 MeV, the detector response to fast neutrons is investigated using a $${^{241}}$$ 241 AmBe neutron source. Sets of detection efficiency functions are then produced via Monte Carlo simulations and post-processing, their validation being performed experimentally and discussed. Finally, the use of the detector to measure the fast neutron activity of very weak n-sources in low neutron background environments, as well as to monitor the cosmic ray variations through the neutron component of the Extensive Air Showers, is considered.

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

“…Consequently, its measurement requires the use of detectors with high efficiency, high signal discrimination capability and long-term stability. The MOSCAB geyser-concept bubble-chamber, which has been in operation in Hall C of the INFN Gran Sasso National Laboratory (LNGS) during the period 2018-2021, has proven to have these characteristics [3].…”

“…The experimental in the range 100 keV ≤ E c ≤ 150 keV shown by Fig. 3 support this interpretation and then, since we are aware that the background runs acquired at critical energies lower than about 150 keV are partly contaminated by signals due to the 222 Rn decay chain, in the analysis we introduced an additional energy cut at E c = 150 keV, which corresponds to an energy threshold E th n = 1.9 MeV for neutrons scattering with Carbon and to an energy threshold E th n = 2.7 MeV for neutrons scattering with Fluorine [3].…”

“…To view a copy of this licence, visit http://creativecomm ons.org/licenses/by/4.0/. Funded by SCOAP3 . SCOAP 3 supports the goals of the International Year of Basic Sciences for Sustainable Development.…”