Absolute efficiency calibration of 6LiF-based solid state thermal neutron detectors

TL;DR

This paper presents a low-cost, silicon-based thermal neutron detector using 6LiF layers, validated by simulations and experiments, suitable for applications like nuclear fuel monitoring.

Contribution

It introduces a novel detector design with validated simulation models, demonstrating effective efficiency calibration and potential for practical neutron detection applications.

Findings

Measured detection efficiency matches simulations

Detectors successfully tested at neutron beam facilities

Potential application in nuclear fuel monitoring

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 the 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. A few 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.