Bruno Barelaud

Thin reactive LiF films for nuclear sensors

Abstract Lithium fluoride (LiF) films are deposited by thermal evaporation on silicon substrates. The substrate temperature and deposition rates influence on the morphology and structure of the films are investigated. It is shown that it is necessary to work with a low deposition rate to have crack-free layers. Also, the substrate temperature has a great influence on coating morphology: the grain size increases with temperature. At the same time, the crystallization state increases up to 300°C. For higher temperatures, recrystallization seems to appear. The grain size increases as well as the grain boundary size.

Proposal of neutron dosemeter based on a differential structure

Abstract Theoretical and experimental knowledge of neutron converter (boron implanted polyethylene) for thermal and fast neutron and its use with etched track detector were previously obtained in our laboratory. These results allow us to propose a neutron dosimetry system based on a differential method. It consists in irradiating two areas of the detector, one covered by a converter (neutron-charged particles), the other uncovered, and in substracting the responses. Here we generalize this principle, by taking into account the albedo and transmission effects in neutron fields(thermal, intermediate, fast) and we choose a neutron converter with the same dosimetric efficiency for thermal and fast neutrons ( In this paper we propose, for routine use of this dosimetric structure, to work on four areas so that it is possible to obtain the contribution of each kind of neutrons and through a systematic analysis of the response an exploitation of the system in three steps in order to optimize reading time.