The HENSA detector
HENSA is an extended energy detector array for neutron spectrometry based on the neutron moderation (Bonner's spheres principle).
HENSA is composed by ten different single thermal neutron counters (3He-filled tubes) of cylindrical shape and 60 cm of active length. The larger active length of the thermal counters provide HENSA with a higher neutron sensitivity in comparison with conventional Bonner's Spheres, which use typically ~2" diameter spherical thermal counters.
In order to provide HENSA with sensitivity at different neutron energy ranges, each thermal counter is embedded in a rectangular box composed by different materials including: high density polyethylene moderators, neutron filters and lead neutron converters.
The HENSA neutron sensitivity is ~5-15 times larger than conventional Bonner's spheres systems in the energy range from thermal up to 10 GeV.
The higher neutron sensitivity allows for:
(i) Improved precision in low radioactivity or underground facilities.
(ii) Temporal response in the scale of tens of minutes to hours for fluctuations of the neutron background at ground or air based measurements.