Semiconductor detector-dosimeter for simultaneously operative measuring of intensity and energy (dose) of electromagnetic, roentgen and gamma-radiation on wide-gap insulating crystals
Kasherininov P., Lodygin A.
A.F. Ioffe Physico-Technical Institute, 194021, St etersburg, Russia

Suggested is a new type of semiconductor detector-dosimeter of radiation (DDR) for simultaneously operative measuring of intensity and energy (dose) of optical, roentgen and gamma stationary as well as pulse radiation. In contrast to usual detector of radiation (DR), DDR forms electrical signals of two types at the output under radiation : photo response pulses with value proportional to intensity of falling radiation and benchmark pulses registering the time of falling of fixed definite energy (dose) of this radiation on the detector surface.

The energy (dose) of electromagnetic and nuclear radiation is widely used in science and technology, but practical devices for operative measuring it directly have not been known. Semiconductor devices used for these purposes measure only the intensity of it radiation. In suggested DDR on wide-gap insulating crystals the electrical charge, developed by registered radiation in crystal can leave the structure only since it value reaches some definite fixed value, because of specific characteristics of used structures. Then the charge accumulated in the crystal flow out of it, producing a short intensity current pulse in electronic circuit of the structure (benchmark pulses), after which the field distribution in the structure returns to its initial state; then the process starts all over again

The steady irradiation of the structure is accompanied by periodic flow of benchmark pulses in the circuit. The radiation energy incident on the surface of the structure during the time between two successive benchmark pulses is determined by the voltage applied to the structure and does not depend on the radiation intensity.

When a periodic radiation pulse irradiates the structure, two type of current pulse flow in its external circuit: benchmark pulses and the pulses of photo response. It becomes possible to make simultaneous measurements of the shape and intensity of the radiation pulses, as well as of the energy per pulse of the radiation from the number of response pulses between two successive benchmark pulses. DDR are not polarized with time under radiation and can be constructed using different type of wide-gap insulator crystals. The high sensitivity of DDR using these crystals to the detected radiation is determined by the high electric field strength in the crystal, 104 V/cm. The proposed DDR can be constructed using two-layer structure: wide-gap semiconductor- dielectric layer with conductivity depending nonlinearly on the electric field in it, (for example, gas-layer).

DDR can be used in different areas of science and techniques:

1. Dosimeters for environment radiation monitoring systems.
2. Registration of the energy (dose) of short pulses of roentgen and laser UV-radiation.
3. Nonpolarizing under radiation detectors on different type of wide-gap insulating semiconductor crystals (for example, natural diamond, BSO)