RESEARCH PROCESSES OF GAMMA RADIATION DETECTOR FOR DEVELOPING A PORTABLE DIGITAL SPECTROMETER

Abstract

When considering methods of combating the illicit circulation of nuclear materials, it is necessary to detect trace amounts of materials, and in many cases not to seize them immediately, but to establish the place of storage, processing, routes of movement, etc. As a result, there is a new demand for isotope identification measurements to meet a wide range of different requirements. Measurements should be carried out in the field in a short time, when results need to be obtained within tens of seconds. The devices with which the personnel work should be small and low-background. Such requirements appear when working to identify cases of illegal trade in nuclear materials and radioactive sources, as well as when solving radiation protection problems and when handling radioactive devices and waste. In this work, new generation radiation sensors and measuring systems based on them have been created, which open up previously unknown possibilities in solving problems of nuclear fuel analysis, increasing the accuracy and efficiency of monitoring technological parameters and the state of protective barriers in nuclear power plants, and creating means for IAEA inspections. For the first time a portable digital gamma-ray spectrometer for radiation reconnaissance in the field was developed and created. Distinctive features of such devices are: The analysis showed that the required value of error due to energy dependence of the sensitivity can be achieved using, for example, Analog Devices 10-bit AD9411 ADCs with a sampling rate of 170 MHz. The number of quantization levels is determined by the requirement to measure the dose rate of gamma radiation with an energy of at least 10 keV. This minimum energy corresponds to the use of 10-bit ADCs. On the basis of the developed model, an ionizing radiation detector for dosimetry was created. Its fundamental difference from known devices is the use of CdZnTe crystals as a primary gamma-ray converter (sensor). The advantages of such a solution, proved by previous studies, made it possible to create a detector with: high resolution, no more than 40 keV; a wider dynamic range of values of the recorded radiation dose rate - from background to emergency operating modes of the reactor; lower value of the energy equivalent of noise.