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New method of efficiency calibration without radioactive source for gamma detector

A technology of detection efficiency and efficiency calibration, applied in instruments, measuring devices, scientific instruments, etc., can solve the problems of slow speed, continuous updating, and a lot of time, and achieve high calculation accuracy, unlimited location, and small measurement workload. Effect

Active Publication Date: 2016-12-07
北京中智核安科技有限公司
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Problems solved by technology

[0005] The relative measurement method has the following limitations: 1. It is necessary to prepare a standard radioactive source or a standard sample source, and for short-lived nuclides, it is necessary to continuously update the standard source
2. It is necessary to know the standard source or sample source and the composition, geometric shape, and nuclide distribution of the object to be measured. When the object to be measured is different from the standard source, self-absorption correction and geometric correction are required, which is very troublesome work
3. For field measurement or non-destructive measurement (body source) measurement, it is difficult to prepare a suitable standard source
However, the method proposed by the former is only suitable for volume sources with axisymmetric (detector symmetric axis) geometry, and the latter method requires a lot of time in both modeling and calculation

Method used

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  • New method of efficiency calibration without radioactive source for gamma detector
  • New method of efficiency calibration without radioactive source for gamma detector
  • New method of efficiency calibration without radioactive source for gamma detector

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Embodiment 1

[0034] Such as figure 1 , figure 2 and image 3 As shown, the first type of detector is a cylindrical detector, and its method is:

[0035] ot is the symmetry axis of the detector, and R is the vertical distance from the center of the detector end face to the edge. H is the vertical distance between the upper and lower ends of the detector. For this type of detector, the detector is characterized in two steps:

[0036] (1) Take a series of points on ol, and calculate the detection efficiency of rays emitted by these points in any direction with energy E. That is to calculate the angular distribution of its detection efficiency E is the particle energy, r, θ and Such as figure 2 As shown, the definition is as follows: take the center of the end face of the detector as the coordinate origin, any radial direction of the end face is the positive direction of the x-axis, and the normal direction outside the end face is the positive direction of the z-axis, and establish ...

Embodiment 2

[0041] Such as Figure 4 As shown, the second type of detector is a well-type detector, its structure and the characterization method when photons are incident from the side of the detector.

[0042] oo”' is the symmetry axis of the detector, r1 is the vertical distance from the center of the detector end face to the inner edge of the detector, r2 is the vertical distance from the center of the detector end face to the outer edge of the detector. H is the vertical distance between the upper and lower end faces of the detector .For this type of detector, characterize the detector in two steps:

[0043] (1) Take a series of points on o"'b, and calculate the detection efficiency of the gamma rays emitted by these points in any direction with the energy E. That is to calculate the angular distribution of the detection efficiency Among them, o”’ is the symmetric center of the bottom end surface of the detector, and b is any point on the intersection line between the inner wall of...

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Abstract

The invention discloses a new method of efficiency calibration without a radioactive source for a gamma detector. The method comprises the following steps: with a given detector structure parameter range (comprising geometric sizes such as a crystal dead layer) as an initial value range, Monte_Carlo calculation and comparison with an experimental measurement result are used to obtain real structure parameters of the detector; according to the real structure parameters, a Monte_Carlo or discrete ordinates (SN) method is used for calculating full-energy peak detection efficiency of rays with specific energy emitted by a point source from any angle on the surface of the detector in the detector, and thus, the detector is characterized; and by using the characterized result of the detector, a numerical integration method is used for calculating the full-energy peak detection efficiency of multiple energy points of any gamma radiation source (a body source, a surface source and a point source), and a detection efficiency calibration curve is fit according to the detection efficiency of the multiple energy points. The new method of efficiency calibration without a radioactive source for the gamma detector provided by the invention has the advantages that the measurement workload is small, the calculation precision is high, the body source position is not limited and the like.

Description

technical field [0001] The invention relates to a passive efficiency calibration method, in particular to a new passive efficiency calibration method of a gamma detector. Background technique [0002] The gamma spectrometer is one of the most widely used instruments in the qualitative analysis and quantitative measurement of radionuclides. The gamma energy spectrum analysis method has the advantages of fast speed, high precision and non-destructive measurement, so it is widely used in in various related fields such as scientific research. [0003] In order to measure the content of radioactive substances in the radioactive source to be tested, it is first necessary to calibrate the efficiency of the gamma spectrometer. The so-called efficiency scale refers to establishing the proportional relationship between the number of gamma particles with energy E emitted per unit time in the radioactive source to be measured and the total energy peak count rate of the corresponding en...

Claims

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Application Information

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IPC IPC(8): G01T1/202
Inventor 肖刚
Owner 北京中智核安科技有限公司
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