Design Of The Virtual Instrument To Absolute Measure ～(220)Rn Based On LabVIEW

With the development of computer technique, traditional instruments is beginning to turn into computerization. The virtual instrument technique has become one of the most important techniques in 21th century. Virtual instrument is the product of modern computer technique, instrument technique and other new technique, whose powerful function has exceeded the conception of instrument itself. With the rapid development of computer technology, computer measurement and control application has been used in various areas. Many nuclear instruments need to be controlled by computer and lots of nuclear data needs to be processed by computer, which gives a great chance for the application of virtual instruments in nuclear areas.The natural science foundation group which is leaded by Professor Zhou Jian Liang of the University of South China has testified the possibility of using a minor-sized glitter room to measure the density of ²²⁰Rn. With the shortenings of the distance between two points from the inside and with ZnS(Ag) daubed equably on the inner surface to improve the use efficiency ofα-particle, the detect efficiency was able to improve to nearly 100%; Through the modification of the glitter room, the dead angles and the inflexions are minished to a level which can be ignored, thus it enables the gas that pass through the system tally with the laminar flow state, and meet with the requirements of flow-gas pattern ²²⁰Rn detecting. The detecting instrument have already been finished, and have been testified to be all right through some particular experiments which operated at the ²²⁰Rn laboratory of the university of South China.Considering the power supply of the flow-gas pattern ²²⁰Rn detecting instrument is the traditional NIM, which has the shortcomings of unwieldiness and will be affected by the surroundings easily, we need to design an inexpensive while steady and flexible ²²⁰Rn detecting instrument, which is exactly the initial idea of this thesis.The task uses the Lab VIEW software as the basic tool to develop the virtual ²²⁰Rn detecting instrument. Compared with the traditional detecting instruments, the virtual instruments only use the laptop and detector, which get rid of the inconveniences of the traditional detecting instruments that is usually restricted by time and place. It can save the money and improve the efficiency of the work.The thesis begins with the notion of absoluteα-particle measuring method and the concept of virtual instruments, its merit and demerit in the area of nuclear measurement first, illustrated the idea in the process of the development of virtual instrument, the blue paint and its develop process. At the non-radioactive laboratory, with the experiment that uses the digital signal and the analog signal, it was tested to be all right with most of the experiment data.Then, the thesis described the theory of the measurement ofα-radioactive using the minor-sized ZnS(Ag) glitter room, measured its detect efficiency and the scale factor. With the experiments that operated at the ²²²Rn laboratory of the University of South China, we conclude that compared with the traditional NIM nuclear measuring instrument, the new virtual instrument's measuring error is within the allowed range, and consist with the standard value. So it meets with the measure requirement under a certain consistency. At last I developed the absolute minor-sized glitter room ²²⁰Rn detecting instrument. The thesis accomplished the mission preferably, achieved the previous design goal. Meanwhile, the newly developed virtual instrument provided a primary experiment platform for the students in the nuclear-electric area.