Method and device for improving detection sensitivity of static collecting method emanometer

Abstract

Provided are a method and device for improving detection sensitivity of a static collecting method emanometer. The detection sensitivity of the static collecting method emanometer is improved by improving collecting efficiency of positively charged 218Po in a static measuring cavity of the static collecting method emanometer, a metal net is arranged between the cavity wall of the measuring cavity and a semiconductor detector to improve the intensity of an electric field nearby the cavity wall of the measuring cavity, a ground wire of a high voltage module is connected to the surface of the semiconductor detector, a high-voltage output wire of the high voltage module is respectively connected to the cavity wall of the measuring cavity and the metal net, and therefore high voltages can be added between the cavity wall of the measuring cavity and the metal net and between the metal net and the surface of the semiconductor detector respectively. Due to the fact that the intensity of the electric field nearby the cavity wall of the measuring cavity can be improved by directly improving the voltages between the cavity wall of the measuring cavity and the metal net, the voltages between the cavity wall of the measuring cavity and the metal net and between the metal net and the surface of the semiconductor detector are adjusted to be proper values, and the collecting efficiency of the static field on the positively charged 218Po can be improved.

Description

technical field [0001] The invention relates to a nuclear radiation detection technology, in particular to a method of improving the positive charge in the measurement cavity of the radon measuring instrument by the electrostatic collection method. 218 The invention discloses a method and a device for improving the detection sensitivity of an electrostatic collection method radon measuring instrument by improving 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 measurement methods and instruments based on different measurement principles. Among them, the electrostatic collection radon measurement instrument has the ability to distinguish energy spectrum due to its high degree of automation. 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 hemispher...

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Problems solved by technology

The cavity wall of the measurement cavity 1 is a conductive metal wall, and its top is an insulating plate. The high voltage is directly applied to the metal wall of the measurement cavity 1 and the surface of the semiconductor detector 6, which leads to a low electric field intensity near the cavity wall of the measurement cavity 1. Measuring the positively charged 218 The drift speed of Po in the electric field is low, and the longer collection time increases the probability of its recombination with the negatively charged OH- ions in the measurement chamber 1, and the collection efficiency on the surface of the semiconductor detector 6 is low

Even if the voltage is increased, due to the characteristics of the structure of the measurement chamber 1, the growth rate of the electric field intensity near the cavity wall is much lower than the growth rate of the voltage. Therefore, after the voltage is increased to a threshold, the collection efficiency will no longer increase with the increase of the voltage.

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