Alpha Spectrum Measured Radon Devices In Key Technologies

Radon is a natural radioactive gas. How to improve the veracity and precision of the radon measurement is very important in the list subjects: uranium mine radioprotection, uranium-free mine radioprotection, using radon technology to survey mine and earthquake forecast. It is very complexity to measure radon and its daughter.This paper consults the key technology in the radon measurement device in the national and international and we thinks over the characteristic of α -ray which emit by radon and its daughter, so that decides to use the α -ray spectrum to measure radon.The key technology in the radon measurement device by α -ray spectrum includes the list key technology: charge-sensitive preamplifier for Si nuclear detector, main amplifier for spectroscopy, pulse shaping circuits, pulse peak holding circuits and α -ray spectrum data acquisition and processing. The paper analyzes the model of the charge-sensitive preamplifier and introduces the charge-sensitive preamplifier designing method .we develop three kinds of charge-sensitive preamplifier and also introduce the debugging process, testing method and results. We also develop the main amplifier, pulse shaping circuits and analyze its characteristic. In the α -ray spectrum data acquisition and processing system we use the LPC2220, it is a 32 bit microprocessor which use the ARM7TDMI-S as its core. The system matches a flash memorizer which capability is 1M. It also has simple hardware and comparatively real time performance because of its microprocessor is a SoC chip. The system not only can used as a α -ray spectrum data acquisition and processing system but also other spectrum devices. In the design we use the large screen LCD and small key board so that its man-machine interface performance is improved.In order to make the paper more practicability, we portray a lot of circuit diagram and present the wave diagram of the key point in the analog circuits. At the same time, we also present the essential program and flow chart in the data acquisition and processing system.