The ring electrode improves the radon exhalation rate measuring instrument 218 Measuring cavity and method for po collection efficiency

Abstract

The ring electrode improves the radon exhalation rate measuring instrument 218 Measuring cavity and method of Po collection efficiency, the inner wall of the measuring cavity is a conductive layer, the bottom is a metal filter, the semiconductor detector is installed in the center of the insulating end cover, the ring electrode is installed in the lower part of the insulating end cover, and the insulating end cover is fixed in the chamber. body opening. Connect the semiconductor detector, the conductive layer on the inner wall of the cavity, and the terminal on the first ring electrode to the high-voltage module through wires, then connect the semiconductor detector to the secondary instrument, and put the measurement cavity into the radon chamber, so that the inside of the cavity The radon concentration in the room is the same as that in the radon room. The high-voltage module separately adjusts the voltage between the conductive layer and the surface of the semiconductor detector and the ring electrode, and uses the secondary instrument to obtain the voltage measured by the semiconductor detector. 218 Po decay count rate. After the measurement chamber is adjusted, the measurement chamber is directly fastened to the surface of the medium to be measured, and then the radon concentration change law in the measurement chamber is measured by a secondary instrument, and then the radon exhalation rate is calculated by data fitting.

Description

technical field [0001] The invention relates to nuclear radiation detection technology, in particular to a measuring instrument for effectively improving radon precipitation rate by adopting annular electrodes. 218 Measuring cavity and measuring method of Po collection efficiency. Background technique [0002] Radon in the environment ( 222 Rn) is the main source of natural radiation to humans. There are many methods and instruments for radon release rate based on different measurement principles. Among them, the electrostatic collection method radon release rate measuring instrument has a high degree of automation and has the ability to discharge energy spectrum. 220 Rn interference has been widely used. . The so-called electrostatic collection method has a measuring cavity, which is generally hemispherical or cylindrical. There is a semiconductor detector on the upper part of the measuring cavity. A high voltage is applied between the measuring cavity wall and the semi...

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Problems solved by technology

This results in the measurement of positively charged 218 The drift velocity of Po under the action of the electrostatic field is small, and the collection time is long. During the collection process, it interacts with negatively charged OH - The probability of ion recombination is large, so that the positively charged 218 The efficiency of Po being collected to the surface of the detector by the electrostatic field is not high, and the detection sensitivity of the radon exhalation rate measuring instrument by the electrostatic collection method is low

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