Measurement chamber for improving 218Po collection efficiency of radon precipitation measuring instrument through multiple detectors and method thereof

Abstract

The invention provides a measurement chamber for improving 218Po collection efficiency of a radon precipitation measuring instrument through multiple detectors and a method thereof. The inner wall ofthe measurement chamber is a conductive layer. The bottom of the chamber body is a metal filter screen. A plurality of semiconductor detectors are annularly mounted on an insulating end cover. The insulating end cover is fixed to the open end of the chamber. The semiconductor detectors in a first annular measuring ring are serially connected. The serially connected semiconductor detectors are connected with a high-voltage module and a secondary instrument. The conductive layer on the inner wall of the chamber body is connected with the high-voltage chamber. The measurement chamber is placed ina radon chamber so that radon concentration in the chamber is same with that in the radon chamber. The voltage between the semiconductor detectors and the conductive layer in the chamber body is adjusted through the high-voltage module. The secondary instrument is used for obtaining a 218Po decaying counting rate which is measured by the semiconductor detectors. After adjustment of the measurement chamber, the measurement chamber is directly buckled with the surface of a to-be-measured medium. Then a radon concentration change rule in the measurement chamber is measured through the secondaryinstrument. Then a radon precipitation rate is calculated through data fitting.

Description

technical field [0001] The invention relates to nuclear radiation detection technology, in particular to a multi-detector to effectively improve the radon exhalation rate measuring instrument 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 for humans. There are many radon exhalation rate methods and instruments based on different measurement principles. Among them, the radon exhalation rate measuring instrument of the electrostatic collection method is highly automated and capable of energy spectrum resolution. 220 The interference of Rn has been widely used. The so-called electrostatic collection method is to have a measuring chamber, the measuring chamber is generally hemispherical or cylindrical, there is a semiconductor detector on the upper part of the measuring chamber, and a high voltage is applied between the measuring chamber wall and th...

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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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