Study Of X-ray Fluorescence Measurement On The Spot

Energy Disperse X-ray Fluorescence Measurement (EDXFM) is an important nuclear analysis technique. The study concentrates on improvement of characteristics of portable Energy Disperse X-ray Fluorescence Measurement Instrument (EDXFMI) for fieldwork, it focuses on systematically studying some key elements of portable EDXFMI system, Such as excitation source, detector, measurement circuit and computerization etc, to resolve defects existing in current portable EDXFMI system, those are low sensitivity ,poor detection limit and small number of determined elements etc. X-ray tube as excitation source has an advantage of consecutive and adjustable energy, which can improve detection limit to ppm level, radioactive isotope as excitation source is feasible for analyzing in site. Si-PIN semiconductor detector with peltier cooler, whose FHWM is about 180ev at 5.9KeV(55Fe) at room temperature, is adopted to be detector in portable EDXFMI system. EDXFMI system is based on both Notebook PC and microprocessor. Multi-Channel Analyzer (MCA) based on microprocessor, which provides 1024 channels and cannot be influenced by floating pulse width with the help of signal discrimination module, has been studied theoretically and experimentally. MCA saves date in RAM and communicates with Notebook PC through RS-232 COM. Object Oriented Program (OOP) language is introduced into building and encapsulating data structure of EDXFM software in WINDOWS format. Its file format is compatible with that of radioactive survey workstation. In addition, Multi-thread technique is adopted to realize multi-thread structure of EDXFM software that can not only display the full spectrometry obtained from MCA, but also complete analysis work in site. The system overcomes difficulties connected with EDXFMI system, establishing better foundation for carrying out high sensitivity and multi-element analysis. Furthermore, the developed system is tested in Dege, Shimian of Sichuan province and Tangshan of Hebei province. Result shows that the new improved system has an advantage of better FHWM and lowers detection limit and is efficient portable EDXFMI system to analyze more elements and to obtain data in site. It improves the work level in geological field, providing another way to validate other methods mutually. It can be applied where need faster analysis and lower detection limit to overcome deficiencies of chemical analysis, benefiting users obviously. It can be predicted that the instrument will play an important role in not only current National Resource Investigation and Western China Exploration but also other fields. It is valuable study worth of spreading.