Citation: Salem, Y.O.; Elazhar, H.; Traore, I.; Riffaud, J.; Nourreddine, A. RPL Neutron Dosimetry in n-γ Fields in Comparison with Polymer Detectors Type CR-39. Polymers 2022, 14, 1801. https://doi.org/10.3390/ polym14091801 Academic Editors: Tomoya Yamauchi and Masato Kanasaki Received: 24 January 2022 Accepted: 20 April 2022 Published: 28 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). polymers Article RPL Neutron Dosimetry in n-γ Fields in Comparison with Polymer Detectors Type CR-39 Youbba Ould Salem 1,2 , Halima Elazhar 1 , Issiaka Traore 2 , Jonathan Riffaud 1 and Abdelmjid Nourreddine 1, * 1 Institut Pluridisciplinaire Hubert Curien, UMR 7178 CNRS, Université de Strasbourg, CEDEX 2, F-67037 Strasbourg, France; yo.salem@unistra.fr (Y.O.S.); elazhar.halima@gmail.com (H.E.); riffaud@unistra.fr (J.R.) 2 Département de Physique, Université des Sciences, des Techniques et Technologies de Bamako, Bamako BP E3206, Mali; traoreamenophis@gmail.com * Correspondence: abdelmjid.nourreddine@iphc.cnrs.fr; Tel.: +33-3-88-10-65-76 Abstract: Previously we characterized radiophotoluminescent (RPL) detectors for measuring both fast and thermal neutrons for personal monitoring. The linear response and angular dependence, which satisfies the ISO 21909 standard makes their application possible in neutron dosimetry. The polymer CR-39 track detectors remain one of the most used dosimeters where neutron radiations are to be measured, but the visualization process is time consuming. The difference between results obtained by RPL and CR-39 has been discussed mainly for fast neutrons. The present study has also looked at thermal neutron dosimetry, where we found few results in the literature for CR-39. Our measurements demonstrate that RPL detectors can be advantageously incorporated into a dosimeter to measure thermal neutrons. Keywords: RPL detector; CR-39 detector; neutron dosimetry; chemical etching; polymer 1. Introduction Neutron dose monitoring in a mixed n-γ field constitutes a current problem of ra- diation protection. Today’s instruments do not respond correctly to one or the other of these radiations. The new values of the radiation weighting factor W R of ICRP 103 for neutrons [1] make it useful to set up a new generation of dosimeters. Compared to other methods of radiation detection, the systems based on RPL techniques are part of a category of dosimeters that have passed all the conformity tests [2], and their use has changed the approach to personal dosimetry in France. However, RPL glass has a relatively low sensitivity to neutrons [3], and that is the reason for using photon dosimetry for the γ part of a mixed n-γ field [4]. Aware of the need for neutron monitoring in the nuclear power industry, research, or medical sector, the French Radiation Protection and Nuclear Safety Institute (IRSN) has introduced the RPL neutron dosimeter. It is a combination of an RPL dosimeter (for γ, X, and β radiations) and a CR-39 dosimeter (for neutrons) that furnish an accurate measurement of the dose received by workers in a mixed n-γ field. CR-39 is a polyallyldiglycol carbonate polymer with chemical properties, which make it one of the most sensitive solid nuclear track detectors in terms of linear energy transfer. Due to its transparency to photon radiations of all energies, it offers many advantages for neutron dosimetry in a mixed n-γ field. Nuclear track detectors have found many applications and particularly so for the development of neutron dosimeters [5–10]. However, the chemical etching processes of the detectors and track counting systems vary according to authors [11–15] and, in any case, long. Hence, it would appear useful to set up standard chemical etching parameters for neutron track detectors or else to develop another system for neutron detection. RPL detec- tors were recently characterized for measuring neutrons [16–18], and it has been suggested that an RPL dosimetry system offers an attractive alternative to neutron dosimeters. The Polymers 2022, 14, 1801. https://doi.org/10.3390/polym14091801 https://www.mdpi.com/journal/polymers