Detection of Thermal Neutrons by CR-39 Using a Boron Implanted Converter

Abstract

Abstract To detect thermal neutrons, we used the (n,a) reaction on 10B. In order to obtain dose equivalent response for thermal neutrons similar to those obtained for fast neutrons with a (CH2)n radiator, we calculated and realised (n,a) converters by implantation of 10B in polyethylene (CH2)n or in iron. These converters were made on the 400 kV H.V.E.E. accelerator of our laboratory. Concentrations of 10B atoms were used between 1014 atoms.cm-2 and 2 x 1015 atoms.cm-2. We compared our theoretical estimates with experimental results from irradiations in C.E.N. Cadarache and A.E.R.E. Harwell, which were obtained using various detectors (CR-39, CAD) behind the converter. Results are given as the number of registered tracks.mSv-1.cm-2. The influence of implantation parameters was also studied. A good agreement exists between calculations and experimental results for both devices; i.e. 10B in (CH2)n and 10B in iron.