Year
2001
Abstract
For various applications in medicine, industry, research, for control of radioactive materials, for advanced warning systems, for nuclear material safeguards and for nuclear inventory monitoring smart and portable gamma spectrometers are needed. Using digital signal processing (DSP) combined with improved spectrum analysing software programs a new generation of portable hand held gamma spectrometers, the so-called fieldSPEC was developed. Besides common gamma spectroscopic functions additional features like dose rate measurements, source finding and automatic nuclide identification are implemented in the unit. Under the German Programme in Support of the International Atomic Energy Agency and in co-operation with the EURATOM Safeguards Office, software was developed for applications in international safeguards. The fieldSPEC integrates multi-channel analyser, amplifier, high voltage power supply, and memory with a wide range of integral detectors. Depending on the application scintillation detectors (NaI(Tl), CsI(Tl), BGO, or plastic) as well as semiconductor detectors (e.g. CdZnTe) can be used. For all currently used detectors the gamma spectrum is stored in 1024 channels. Up to 50 spectra can be stored in the fieldSPEC device and downloaded via an IR interface to an external computer for further qualitative and quantitative analysis. The paper describes the spectroscopic characteristics in detail. For automatic nuclide identification a built-in library consisting of about 75 nuclides is implemented. The operator can use the complete library or can select from the library the nuclides of interest. The nuclide identification is based on the matrix method, e.g., the sampled spectrum is assumed as the linear combination of reference spectra of individual nuclides. For dose rate measurements an integral scintillation or semiconductor detector is used in the low dose rate range (up to a few hundred µSv/h). For higher dose rate fields a built-in Geiger Mueller (GM) tube is applied to determine dose rates up to 1 Sv/h. The radiological properties with respect to energy response, angular response, and overall accuracy are described in the paper. Different application software programs for uranium enrichment calculations and for the determination of the active length of fuel elements were developed in co-operation with the International Atomic Energy Agency and EURATOM. Results of these studies are presented.