Development and characterization of neutron-sensitive optically stimulated luminescence (OSL) detectors

Scope and Method of Study. This work presents the development and characterization of new neutron-sensitive optically stimulated luminescence (OSL) detectors. These new neutron-sensitive detectors, known as Luxel-n, were developed at Oklahoma State University (OSU) using a combination of an OSL material (Al2O3:C) and 6Li-based neutron converters (6Li2CO3 or 6LiF) in the form of powder, subsequently processed and printed in the form of long tapes. This investigation includes various sample preparation procedures to optimize the neutron sensitivity of the powder, various characterization tests, such as determination of gamma and neutron response and sensitivity and energy responses to various types of neutron and photon sources, using neutron sensitive OSL detector, Luxel-n. In addition, we introduced a new approach to improve neutron dosimetry by discriminating neutrons and gamma-components in mixed fields.;Findings and Conclusions: From the optimization of neutron-sensitive powder investigation, we showed that annealing of mixed powder/pellet helps improving particle binding and we suggest annealing at 723°C maximum temperature at 5°C/min for 1-2 h annealing duration. We observed the presence of ∼60 mum size particles in pelleted heated <90 mum mixed powder sample, showing effectiveness of annealing treatment. Also, we showed that higher neutron sensitivity can be obtained for ∼50 mum size particles. In characterization of neutron-sensitive Luxel-n detectors, the results show that gamma-sensitivity depends on the thickness of the tape material whereas, Rn/Rgamma ratio do not. Also, the relative comparison of Rn/Rgamma ratio shows that the neutron sensitivity of OSLD is ∼60% of neutron sensitivity of neutron-sensitive TLD. We concluded that Luxel-n detectors are highly sensitive to low energy thermal neutrons compared to fast neutrons. The result also showed that the neutron sensitivity of Luxel-n detector decreases with increase in energy for monoenergetic neutrons, and photon energy response of Luxel-n detectors is very similar to that of Luxel detectors. The result showed that transmission POSL and modified Riso POSL systems can detect doses below 0.1 mGy. Finally, we showed that from SUV/S F-center vs. Rn/Rn+gamma calibration curve plotted for mixed field, the discrimination of neutron and gamma-component can be done using single Luxel-n detector.