Inorganic Scintillation Crystals for Neutron Detection

Inorganic scintillators play an important role in the detection and spectroscopy of gamma and X-rays, as well as in neutrons and charged particles. For a variety of applications, new inorganic scintillation materials are being studied. New scintillation detector applications arise continuously and, consequently, the interest in the introduction of new fast scintillators becomes relevant. Scintillation crystals based on cesium iodide (CsI) have relatively low hygroscope, easy handling and low cost, features that favor their use as radiation detectors. In this work, lithium and bromine doped CsI crystals were grown using the vertical Bridgman technique. In this technique, the charge is maintained at high temperature for 10 h for the material melting and complete reaction. The temperature gradient 21 deg. C/cm and 1 mm/h descending velocity are chosen as technique parameters. After growth is finished, the furnace is cooled at a rate of 20 deg. C/h to room temperature. The concentration of the lithium doping element (Li) studied was 10^-3 M and the concentration of the bromine was 10^-2 M. Analyses were carried out to evaluate the scintillators developed concerning the neutron from the AmBe source, with energy range of 1 MeV to 12 MeV. Lithium can capture neutrons without gamma-ray emission, thus, reducing the back-ground. The neutron detection reaction is ⁶Li(n, α)³H with a thermal neutron cross section of 940 barns. In this paper, it was investigated the feasibility of the CsI:Li and CsI:Br crystals as neutron detectors for monitoring, due to the fact that in our work environment there are two nuclear research reactors and calibration systems. (authors)