Neutron detection devices with ⁶LiF converter layers - 061085

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 low cost 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. Even though their detection efficiency is only around 8%, the gamma rejection performance and the rather low cost as compared to ³He tubes, make these detectors quite interesting for several applications, especially those with continuous monitoring purposes. (authors)