Abstract
The demand for new thermal neutron detectors as an alternative to 3He tubes in research, industrial, safety and homeland security applications, is growing. These needs have triggered research and development activities about new generations of thermal neutron detectors, characterized by reasonable efficiency and gamma rejection comparable to 3He tubes. In this paper we show the state of art of a promising lowcost technique, based on commercial solid state silicon detectors coupled with thin neutron converter layers of 6LiF deposited onto carbon fiber substrates. Several configurations were studied with the GEANT4 simulation code, and then calibrated at the PTB Thermal Neutron Calibration Facility. The results show that the measured detection efficiency is well reproduced by the simulations, therefore validating the simulation tool in view of new designs. These neutron detectors have also been tested at neutron beam facilities like ISIS (Rutherford Appleton Laboratory, UK) and n_TOF (CERN) where a few samples are already in operation for beam flux and 2D profile measurements. Forthcoming applications are foreseen for the online monitoring of spent nuclear fuel casks in interim storage sites.
Highlights
THE lack and the increasing cost of 3He have triggered in the last years a worldwide R&D program investigating new techniques for neutron detection
In this paper we report on the calibration of a few samples of this solid state neutron detector in a thermal neutron field, and the results are compared to the respective GEANT4 simulations
The triton and the alpha particle emitted from the reaction (1) following a neutron capture have well defined energies, which are degraded after crossing the residual converter layer thickness and the thin air layer between the converter face and the silicon detector
Summary
THE lack and the increasing cost of 3He have triggered in the last years a worldwide R&D program investigating new techniques for neutron detection. For many applications a realistic alternative is needed to 3He-based neutron detectors applications are already in use, like for instance at the n-TOF spallation neutron beam facility [13],[14]. In this paper we report on the calibration of a few samples of this solid state neutron detector in a thermal neutron field, and the results are compared to the respective GEANT4 simulations. Which so far have been the most widely used systems, as they
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