MODEL OF PHYSICAL PROCESSES IN THE PRIMARY AND SECONDARY CONVERTERS OF THE DETECTOR FOR RADIATION MONITORING SYSTEMS
DOI:
https://doi.org/10.17721/2519-481X/2023/81-02Keywords:
detector, primary and secondary converters, ionizing radiation energy, signal pulse spread, radiation monitoring systemsAbstract
The level of development and application radiations technologies is largely determined by the state of nuclear instrumentation. The advent of modern semiconductor sensors for the first time connected nuclear instrumentation and electronics into a single complex - semiconductor detector. It combines a semiconductor primary converter of ionizing radiation (sensor), secondary converter of information from the sensor (electronics) and software for processing this information, interconnected in terms of problem being solved and parameters.
The block diagram of the detector consists of two main parts: the primary converter of ionizing radiation (IR) energy into an electrical signal - sensor; secondary converter of this electrical signal.
The characteristics of the detector are determined mainly by the physical properties of the semiconductor crystal as the sensitive element of the primary transducer, as well as by the features of process recording the electrical signal.
The process of registering IR consists of converting a non-electrical quantity that characterizes it into an electrical signal. In other words, one type of energy is converted - IR energy - into another, more convenient for processing and storing information. A current or voltage pulse occurs in a radiation sensor directly as a result ionization of its active medium - a semiconductor; this pulse carries extensive information. First of all, it is correlated with the time of the nuclear process. In addition, the pulse marks fact that radiation is emitted within the solid angle at which sensor is visible from the source. Pulse amplitude often serves as a measure of the energy loss of radiation in the sensor. The pulse shape differs for different types of radiation, as well as for different areas and angles of radiation entering the sensor.
In this work, model of gamma radiation detector is created as a single system of primary and secondary converters. It contains a physical analysis and analytical representation of the processes occurring in CdZnTe-sensor and electronic preamplifier. It is shown that the collection of charges in sensor varies over time, which leads to a scatter of signal pulses in duration and amplitude. In this regard, the model shows need to use a charge-sensitive pre-amplifier.
The main advantage of the model is the solution to problem of optimizing signal-to-noise ratio in the detector.
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