Development Of A New Standard Device For 2??,2?? Particle Emissivity

It is common to use alpha and beta surface contamination meters to detect whether radioactive contamination has occurred or has been effectively removed.Large-area alpha and beta standard planar sources are commonly used to characterize or calibrate these instruments,and standard 2??,2?? particle emissivity devices with windowless proportional counters are commonly used to calibrate these large-area alpha and beta planar sources.The 2??,2?? particle emissivity measuring device is not easy to carry to the site for emissivity measurement,which use a large NIM plug-in system in laboratories.This project adopts a modular design method,combined with a highly integrated CPLD device,to develop a new standard device for 2??,2?? particle emissivity.The instrument is small in size and easy to carry,and can meet the requirements of on-site measurement of emissivity.System design can be divided into three parts: hardware circuit design,embedded program design and PC software design.The hardware circuit design includes detector selection,preamplifier design,system power supply design,signal conditioning circuit design,signal discrimination circuit design,signal extraction circuit design,CPLD,MCU hardware circuit design and serial communication circuit design.The process of maintaining,collecting and quantifying the output of the electronic pulse signal from the detector to the peak value of the voltage pulse signal is then sent by the MCU to the host computer through the serial port;the embedded software design mainly includes the CPLD module and the MCU module.The design of the serial communication protocol;the software design of the upper computer includes the development of the energy spectrum measurement system and the establishment of the rate measurement system,which realizes the functions of data collection and processing,file storage and opening.The new 2??,2?? particle emissivity standard device developed by this project realizes the energy spectrum measurement of the plane source,the automatic measurement of the high-pressure floor curve and the separate measurement of the rate meter.After systematic testing,the system parameters measured by the ? and ? plane sources are determined.Under the determined parameters,the plane sources of different types and different magnitudes are measured,the measurement deviation is better than 3%,and the short-term and long-term stability are better than 1%,which meets the requirements of system indicators.