The Development Of Radiation Detector Based On Photodiode

Semiconductor detectors and scintillation detector are two main detector of nuclear radiation detector,in recent years, as a semiconductor photodiode detector has a rapid development, especially in combination photodiode and scintillation detectors by virtue of its small size, wide range, low-cost advantages gradually have a more broad application prospects. The purpose of this paper is to achieve two photodiode based radiation detection equipment research and development of hardware and software, namely medical X-ray radiation dosimeter and the radiation source vehicle monitor, to probe X, γ-ray radiation.The medical X-ray dosimeter is used to measure exposure dose, tube voltage, exposure time and other parameters of X-ray machines to ensure radiation safety. The photodiodes operate in the photovoltaic mode, two photodiode output two channels of DC current signal, the current input current sense amplifier to be amplified voltage signal, the voltage signal go through the programmable gain amplifier, low-pass filtering, analog to digital conversion module into the MCU Atmega128 processing, measurement data transport by serial ports to the host computer for data operation, display and storage.Radiation source vehicle monitor is placed in the radiation source monitor to measure radiation dose in the vehicle, the photodiodes operate in photoconductive mode, the reverse bias voltage of 30 V, the output current pulses from the charge sensitive amplifier signal is converted into a voltage signal, and then amplified and filtered into the MCU chip comparators to complete pulse count.This issue contains two parts of program, the lower machine software program and upper computer software program. The lower computer application development platform is ICC for AVR 7.0 based on C, the program supplies circuit modules driver. Medical X-ray dosimeter PC software main function is computed data, display and storage, respectively VB6.0 and C #.NET development environment.This medical X-ray dosimeter can detect tube voltage, exposure dose, exposure time and other parameters by one exposing, the tube voltage and dose measurement accuracy of less than 2%, the tube voltage measurement range of 40kV-150 kV, exposure time measurement resolution of 0.5 ms, instrument performance meets the relevant standards. The radiation source vehicle monitor is tested by γ-ray, its dose rate measurement range of 0.1μGy / h-2mGy / h, it can distinguish radioactive sources in the car, the car is not radioactive, radioactive leak,these three cases, to meet the actual application requirements.