Measurement chamber for improving 218Po collection efficiency of radon precipitation rate measuring instrument through annular electrode and method thereof

Abstract

The invention discloses a measurement chamber for improving 218Po collection efficiency of a radon precipitation rate measuring instrument through an annular electrode and a method thereof. The innerwall of the measurement chamber is a conductive layer. The bottom of the measurement chamber is provided with a metal filter screen. A semiconductor detector is mounted at the central part on an insulating end cover. The annular electrode is mounted at the lower part of the insulating end cover. The insulating end cover is fixed to the open end of the chamber. The semiconductor detector, the conductive layer on the inner wall of the chamber and a terminal on the first annular electrode are connected with a high-voltage module through leads. The semiconductor is connected with a secondary instrument. The measurement chamber is placed in a radon chamber so that radon concentration in the chamber is same with that in the radon chamber. The high-voltage module respectively regulates voltage between the conductive layer and the semiconductor detector and the annular electrode. The secondary instrument is used for obtaining a 218Po decaying counting rate which is measured by the semiconductor detector. After the measurement chamber is adjusted, the measurement chamber directly buckles the surface of a to-be-measured chamber, and then the radon concentration change rule in the measurementchamber is measured through the secondary instrument. Then the radon precipitation rate is calculated through data fitting.

Description

technical field [0001] The invention relates to nuclear radiation detection technology, in particular to a method of using a ring electrode 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 measurin...

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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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