Energy spectrum peak position linear compensation method

Abstract

The invention discloses an energy spectrum peak position linear compensation method, which comprises the following steps of: receiving a ray signal generated by a standard sample by using a detector, converting a detector pulse into a trapezoidal forming pulse, converting the amplitude of the trapezoidal forming pulse into a channel address, and forming original energy spectrum data of the standard sample; calculating a linear relation of energy spectrum peak positions according to the original energy spectrum data of the standard sample to obtain a slope and an intercept in a linear relation function; and adjusting the conversion parameter from the detector pulse to the trapezoidal shaping pulse through the corresponding relation between the slope and the intercept and the gain and the baseline value of the trapezoidal shaping pulse, thereby changing the actual value of the channel address corresponding to the detector pulse, and obtaining the energy spectrum data after linear compensation. According to the energy spectrum peak position linear compensation method disclosed by the invention, before neutron activation analysis spectrum unfolding, it can be ensured that the energy spectrum element peak position is consistent with the standard spectrum, and the energy spectrum analysis precision is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclide identification and analysis, and particularly relates to a method for linear compensation of energy spectrum peak positions. Background Art

[0002] Instruments using prompt gamma-ray neutron activation analysis technology can be used for qualitative and quantitative analysis of the elemental composition of substances. They are widely used in cement, coal, steel, metallurgy, mining, power plants and bauxite industries, and play an important role in energy conservation and emission reduction, process optimization and control, and quality improvement in industrial enterprises.

[0003] Currently, the analytical principle of this type of instrument is to irradiate the material with neutrons. The neutrons react with the atomic nuclei of the elements in the material, and different elemental nuclei emit characteristic gamma rays with different energies and intensities. By measuring the energy and intensity of these characteristic gamma rays, the type and content of the element are analyzed. In actual application, due to the aging of detectors and electronic components, changes in ambient temperature, and changes in count rate, the zero point of the measured gamma-ray energy spectrum and the peak positions of the element peaks will drift. Summary of the Invention

[0004] The present invention provides a method for linear compensation of energy spectrum peak position, aiming to solve the above technical problems.

[0005] The specific technical solutions adopted to solve the above problems are: Step 1: Use a detector to receive the radiation signal generated by the standard sample, convert the detector pulse into a trapezoidal shaped pulse, and convert the trapezoidal shaped pulse amplitude into a channel address to form the original energy spectrum data; Step 2: Calculate the linear relationship function between the actual value and theoretical value of the standard sample element peak position channel address based on the measured original energy spectrum data of the standard sample; Step 3: According to the linear relationship function between the actual value and theoretical value of the peak position of the standard sample element, set two parameters g2 and d to adjust the amplitude conversion gain and baseline value of the trapezoidal forming pulse to obtain the energy spectrum data after linear compensation.

[0006] Furthermore, in step 1, the detector pulse signal with a pulse amplitude of a1 is shaped into a trapezoidal shaped pulse with a pulse amplitude of a2, wherein a2=g1·a1, wherein g1 is an amplitude conversion gain; The trapezoidal pulse amplitude a2 is converted into the original energy spectrum data through the conversion formula c=a2 / n, where c is the channel address, the value of c is obtained by rounding down the result calculated according to the conversion formula, and n is the conversion coefficient from amplitude to channel address, and the value of n satisfies the positive integer power of 2.

[0007] Furthermore, the linear relationship function expression in step 2 is y=k·x+b, where x is the actual value of the element peak position, y is the theoretical value of the element peak position, and parameters k and b are the slope and intercept values obtained by fitting calculation.

[0008] Further, in step 3, g2 is an adjustment parameter of the amplitude conversion gain of the trapezoidal shaped pulse, and d is the baseline value of the trapezoidal shaped pulse, wherein g2=k, d=b; The conversion relationship between the detector pulse signal and the trapezoidal shaped pulse is adjusted by g2 and d, that is, a3=g3·a1+d, where a3 is the adjusted trapezoidal shaped pulse amplitude and g3=g2·g1; The pulse amplitude a3 after adjustment is converted into the formula c=a3 / n to obtain the channel address corresponding to the pulse amplitude after adjustment, thereby obtaining the energy spectrum data after peak linear compensation.

[0009] The beneficial effects of the present invention are: The method of the present invention has a simple structure, is combined with the trapezoidal forming, has a small amount of calculation, and is easy to implement on hardware equipment.

[0010] The present invention can ensure that the peak positions of energy spectrum elements are consistent with the standard spectrum before neutron activation analysis spectrum analysis is performed, thereby improving the accuracy of energy spectrum analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the implementation process of the present invention; Figure 2 Schematic diagram of the detector pulse signal and trapezoidal shaped pulse. DETAILED DESCRIPTION

[0012] The technical solution of the invention is described with reference to the accompanying drawings.

[0013] This embodiment relies on a digital multi-channel pulse amplitude analyzer consisting of a high-speed signal sampling circuit, an FPGA (field programmable gate array), and an ARM processor to implement a linear compensation method for the neutron activation energy spectrum peak. The high-speed signal sampling circuit digitizes the pulse signal output by the detector. The digitized detector signal undergoes amplitude analysis in the FPGA, ultimately generating energy spectrum data that is transmitted to the ARM processor for further processing. A program is run in the digital multi-channel pulse amplitude analyzer to achieve linear compensation for the neutron activation energy spectrum peak. The specific implementation steps are as follows: In step S1, a NaI detector is used to receive gamma rays generated by a standard sample. A 12-bit high-speed ADC samples the detector pulse signal at a sampling frequency of 40 MHz. The detector pulse signal, which has been digitized by the high-speed signal sampling circuit, is converted from amplitude to channel address. Assuming the pulse amplitude of the detector pulse signal (1) is a1, it is converted into a trapezoidal shaped pulse (2) using a trapezoidal shaping algorithm. The pulse amplitude of the trapezoidal shaped pulse (2) is a2. The amplitudes of the two satisfy a linear relationship: a2 = g1·a1, where g1 is the amplitude conversion gain, which is a constant pre-set according to system characteristics and design requirements and is used to accurately control the amplitude conversion ratio of the pulse signal.

[0014] The amplitude a2 of the trapezoidal pulse (2) is converted according to the conversion formula c = a2 / n to obtain the original energy spectrum data of the standard sample. Here, c represents the channel address, which takes an integer value and is a key parameter in the energy spectrum data. It is used to identify the amplitude range of the pulse signal corresponding to different energies. n is the conversion coefficient from amplitude to channel address. The value of n satisfies the positive integer power of 2 and is also a fixed value determined by the calibration and design of the system. It is used to accurately map the pulse amplitude to the corresponding channel address.

[0015] Step S2 uses the raw energy spectrum data of the standard sample described in step S1 to analyze the relationship between the actual and theoretical values of the element's peak locations. The actual values of the element's peak locations are the location data obtained through measurement, while the theoretical values are the location data determined based on the element's known energy characteristics. Using mathematical methods such as linear regression analysis, the parameters k and b in the linear relationship function y = k·x + b are calculated. Here, x represents the actual value of the element's peak location, and y represents the theoretical value of the element's peak location. The parameter k reflects the slope of the relationship between the actual and theoretical values, while b represents the intercept. Together, these parameters determine the linear deviation between the actual measurement result and the theoretical expectation.

[0016] In step S3, two key parameters g2 and d are set to adjust the amplitude and baseline of the trapezoidal shaped pulse (2). g2 is used as the adjustment parameter for the amplitude conversion gain of the trapezoidal shaped pulse (2), and d is used as the baseline value of the trapezoidal shaped pulse (2). In order to achieve linear compensation of the peak position, g2 = k and d = b are set, that is, the linear relationship function parameters calculated in step S2 are directly applied to the subsequent adjustment process.

[0017] The conversion relationship from the detector pulse signal (1) to the trapezoidal shaped pulse (2) is adjusted using the set parameters g2 and d. The adjusted pulse amplitude a3 satisfies the formula a3 = g3 · a1 + d, where g3 = g2 · g1. In this way, the initial amplitude conversion gain g1 and the adjustment parameter g2 are comprehensively considered to achieve precise adjustment of the pulse amplitude.

[0018] The adjusted pulse amplitude a3 is converted according to the conversion formula c=a3 / n to obtain the channel address c corresponding to the adjusted pulse amplitude. This process effectively compensates for linear shifts in element peak channel addresses caused by system errors or other factors, thereby obtaining energy spectrum data with linear peak position compensation.

Claims

1. A method for linear compensation of energy spectrum peak position, characterized by: Step 1: Use a detector to receive the radiation signal generated by the standard sample, convert the detector pulse into a trapezoidal shaped pulse, and convert the trapezoidal shaped pulse amplitude into a channel address to form the original energy spectrum data; Step 2: Based on the original energy spectrum data of the measured standard sample, calculate the linear relationship function between the actual value and the theoretical value of the peak position of the standard sample element; Step 3: According to the linear relationship function between the actual value and theoretical value of the peak position of the standard sample element, set two parameters g2 and d to adjust the amplitude conversion gain and baseline value of the trapezoidal forming pulse to obtain the energy spectrum data after linear compensation.

2. The method for linear compensation of energy spectrum peak position according to claim 1, characterized in that: The original energy spectrum data is: shaping the detector pulse signal with a pulse amplitude of a1 into a trapezoidal shaped pulse with a pulse amplitude of a2, wherein a2=g1·a1, wherein g1 is the amplitude conversion gain; The trapezoidal pulse amplitude a2 is converted using the amplitude-to-channel address conversion formula c=a2 / n to obtain the original energy spectrum data, where c is the channel address, and the value of c is obtained by rounding down the result calculated according to the conversion formula. n is the amplitude-to-channel address conversion coefficient, and the value of n satisfies a positive integer power of 2.

3. The method for linear compensation of energy spectrum peak position according to claim 1, characterized in that: The linear relationship function between the actual value and theoretical value of the element peak position is: The linear relationship function expression is y=k·x+b, where x is the actual value of the element peak position, y is the theoretical value of the element peak position, and the parameters k and b are the slope and intercept values obtained through fitting calculation.

4. The method for linear compensation of energy spectrum peak position according to claim 1, wherein: The two parameters g2 and d: g2 is the adjustment parameter of the amplitude conversion gain of the trapezoidal shaped pulse, and d is the baseline value of the trapezoidal shaped pulse, where g2=k, d=b; The conversion relationship between the detector pulse signal and the trapezoidal shaped pulse is adjusted by g2 and d, that is, a3=g3·a1+d, where a3 is the adjusted trapezoidal shaped pulse amplitude and g3=g2·g1; The pulse amplitude a3 after adjustment is converted into the formula c=a3 / n to obtain the channel address corresponding to the pulse amplitude after adjustment, thereby obtaining the energy spectrum data after peak linear compensation.

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