title: Development and calibration of a real-time airborne radioactivity monitor using direct gamma-ray spectrometry with two scintillation detectors.
abstract: The implementation of in-situ gamma-ray spectrometry in an automatic real-time environmental radiation surveillance network can help to identify and characterize abnormal radioactivity increases quickly. For this reason, a Real-time Airborne Radioactivity Monitor using direct gamma-ray spectrometry with two scintillation detectors (RARM-D2) was developed. The two scintillation detectors in the RARM-D2 are strategically shielded with Pb to permit the separate measurement of the airborne isotopes with respect to the deposited isotopes.In this paper, we describe the main aspects of the development and calibration of the RARM-D2 when using NaI(Tl) or LaBr3(Ce) detectors. The calibration of the monitor was performed experimentally with the exception of the efficiency curve, which was set using Monte Carlo (MC) simulations with the EGS5 code system. Prior to setting the efficiency curve, the effect of the radioactive source term size on the efficiency calculations was studied for the gamma-rays from (137)Cs. Finally, to study the measurement capabilities of the RARM-D2, the minimum detectable activity concentrations for (131)I and (137)Cs were calculated for typical spectra at different integration times.
authors.affiliation: Unitat de Física Mèdica, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, ES-43201 Reus, Tarragona, Spain. Electronic address: ramon.casanovas@urv.cat.
authors.forename: R
authors.initials: R
authors.lastname: Casanovas
authors.affiliation: Servei de Protecció Radiològica, Servei de Recursos Científics i Tècnics, Universitat Rovira i Virgili, ES-43007 Tarragona, Spain.
authors.forename: J J
authors.initials: JJ
authors.lastname: Morant
authors.affiliation: Unitat de Física Mèdica, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, ES-43201 Reus, Tarragona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Salvadó
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D002588:Cesium Radioisotopes / Q000032:analysis*; D003198:Computer Simulation; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D007457:Iodine Radioisotopes / Q000032:analysis*; D057230:Limit of Detection; D009010:Monte Carlo Method; D012588:Scintillation Counting / Q000295:instrumentation / Q000379:methods*; D013051:Spectrometry, Gamma / Q000379:methods*
chemical_list: D000396:Air Pollutants, Radioactive; D002588:Cesium Radioisotopes; D007457:Iodine Radioisotopes
keywords: Efficiency calculation; LaBr(3)(Ce); Monte Carlo simulation; NaI(Tl); Scintillation gamma-ray spectrometry