Scintillator gamma spectrometer LED spectrum stabilization system and method based on current type spectrometer

Abstract

The invention discloses a scintillator gamma spectrometer LED spectrum stabilization system and method based on a current type spectrometer, and relates to the field of spectrometer equipment, the system comprises a scintillator detector, a light guide, an LED, an optical attenuator, an electronics system and an upper computer; the electronic system comprises a photoelectric converter, a current type pre-amplifier and a current type digital pulse processor, and the system is not provided with a temperature acquisition system, and can more accurately reflect the characteristics of a scintillator detector of spectral line drifting, thereby achieving a more accurate spectrum stabilization effect, and reducing the complexity of the system. Only the change of the base line is considered, and the original signal pulse can be correctly extracted after the base line is recovered by the spectrometer through the base line deduction algorithm, so that the dead time is close to zero, the counting rate loss in the spectrum stabilization process can be effectively reduced, and the measurement precision is improved.

Description

Technical Field

[0001] The present application relates to the field of spectrometer equipment, and in particular to a scintillator gamma spectrometer LED spectrum stabilization system and method based on a current-type spectrometer. Background Art

[0002] Scintillator gamma (γ) spectrometers are widely used in radioactivity measurement due to their good energy linearity, high luminous efficiency, high detection efficiency and easy background reduction. The detector of this type of spectrometer is usually composed of scintillation crystals, photoelectric conversion elements and corresponding signal processing devices, with relatively low cost and high reliability. However, this type of spectrometer has a serious defect, which is that it is easy to have spectral line drift. Spectral line drift will lead to errors in energy window calculation, errors in nuclide identification methods and other inaccurate measurement phenomena. According to different influencing factors, the causes of spectral line drift can be divided into the following three points: 1) Temperature change: Temperature change will affect the light yield, photomultiplier coefficient and gain multiple of the scintillator; 2) Voltage instability: The unstable system voltage leads to unstable gain of the photomultiplier tube (PMT) and electronic components, especially the unstable high-voltage power supply of the photomultiplier tube, which is more likely to cause a large offset in the output pulse; 3) Magnetic field change: The deflection angle and radius of the photoelectrons in the photomultiplier light in magnetic fields of different intensities and directions are different, which will change the gain coefficient of the photomultiplier tube.

[0003] Among the spectrum stabilization methods currently available, the most widely used in products is the LED-based spectrum stabilization method. Since LED spectrum stabilization can only eliminate the temperature drift problem of the photomultiplier tube and the back-end electronics, and cannot eliminate the temperature effect of the scintillator itself, the current common LED-based spectrum stabilization method is divided into two parts: one is to compensate for the temperature drift of the scintillator itself, and the other is to perform LED spectrum stabilization on the circuit behind the scintillator.

[0004] However, the aforementioned LED-based spectrum stabilization method has the following disadvantages: 1) The temperature-compensated scintillator spectrum stabilization method generally uses multiple temperature detectors to measure the detector surface temperature, and then takes the average value as the detector temperature. First, the temperature inside and on the surface of the scintillator is not consistent, especially when a large volume of scintillator is used. In this way, there is a certain error between the measured temperature and the actual temperature, resulting in inaccurate spectrum stabilization. At the same time, installing a thermometer on the surface of the detector will increase the complexity of the entire system structure and electronics. 2) The current LED spectrum stabilization method is to use narrow LED pulses to drive the LED to emit light. The light emitted by the LED is a short pulse light, similar to the light emitted by the scintillator. After the LED spectrum stabilization is turned on, a large amount of signal is generated in a short time, forming an LED peak on the energy spectrum, and then using this LED peak to stabilize the spectrum. Since the signal generated by the pulsed LED spectrum stabilization is similar to the nuclear signal, there is dead time. Summary of the invention

[0005] The purpose of this application is to provide a scintillator gamma spectrometer LED spectrum stabilization system and method based on a current-type spectrometer, which can reduce the complexity of the system structure and have a dead time close to zero, which can effectively reduce the count rate loss during the spectrum stabilization process and improve the measurement accuracy.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a scintillator gamma spectrometer LED spectrum stabilization system based on a current-type spectrometer, comprising a scintillator detector, a light guide, an LED, an optical attenuator, an electronics system and a host computer; the electronics system comprises a photoelectric converter, a current-type preamplifier and a current-type digital pulse processor;

[0008] The scintillator detector is used to generate a fluorescence signal;

[0009] There is a hole area on the light guide, and an LED and a light attenuator are arranged in the hole area; the light attenuator is used to attenuate the LED light signal generated by the LED to obtain an attenuated light signal;

[0010] The photoelectric converter is used to: perform photoelectric conversion on the fluorescence signal and the attenuated light signal to obtain a current signal;

[0011] The current type preamplifier is used to: amplify the current signal to obtain an amplified current pulse signal;

[0012] The current-type digital pulse processor is used to: extract the baseline height of the amplified current pulse signal, and remove the baseline in the amplified current pulse signal based on the baseline height to obtain a current signal pulse;

[0013] The host computer is used to: preprocess the current signal pulse to obtain a preprocessed current signal pulse; perform feature extraction on the preprocessed current signal pulse to obtain pulse feature parameters; determine the final spectral line drift channel number based on the pulse feature parameters and the baseline height, and perform spectral line correction processing based on the final spectral line drift channel number.

[0014] Optionally, in determining the final spectral line drift channel number according to the pulse characteristic parameter and the baseline height, and performing spectral line correction processing according to the final spectral line drift channel number, the host computer is used to:

[0015] Determine the final spectral line drift channel number according to the pulse characteristic parameter, the baseline height and the third spectral line drift relationship; perform spectral line correction processing according to the final spectral line drift channel number; the third spectral line drift relationship is a mapping relationship between the pulse characteristic parameter, the baseline height and the spectral line drift;

[0016] Or, determine the number of spectral line drift channels corresponding to the scintillator according to the pulse characteristic parameter and the first spectral line drift relationship; determine the number of spectral line drift channels corresponding to the electronic system according to the baseline height and the second spectral line drift relationship; determine the number of co-acting spectral line drift channels according to the number of spectral line drift channels corresponding to the scintillator, the number of spectral line drift channels corresponding to the electronic system and the fourth spectral line drift relationship; determine the number of co-acting spectral line drift channels as the final number of spectral line drift channels; perform spectral line correction processing according to the final number of spectral line drift channels; the number of co-acting spectral line drift channels is the number of spectral line drift channels caused by the combined action of the scintillator and the electronic system; the first spectral line drift relationship is the mapping relationship between the pulse characteristic parameter and the spectral line drift; the second spectral line drift relationship is the mapping relationship between the baseline height and the spectral line drift; the fourth spectral line drift relationship is the mapping relationship between the first spectral line drift, the second spectral line drift and the third spectral line drift; the first spectral line drift is determined based on the first spectral line drift relationship; the second spectral line drift is determined based on the second spectral line drift relationship; the third spectral line drift is determined based on the third spectral line drift relationship;

[0017] Or, the number of spectral line drift channels corresponding to the scintillator is determined according to the pulse characteristic parameters and the first spectral line drift relationship; the number of spectral line drift channels corresponding to the electronic system is determined according to the baseline height and the second spectral line drift relationship; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system constitute the final number of spectral line drift channels; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system are used respectively to perform spectral line correction processing.

[0018] Optionally, the scintillator gamma spectrometer LED spectrum stabilization system based on the current type spectrometer further includes a spectrum line drift relationship determination module; the spectrum line drift relationship determination module is used to:

[0019] The first experiment is carried out by a host computer to obtain the output pulse waveform and spectral line drift of the current-type preamplifier at different temperatures, and the output pulse waveform is standardized, and the pulse characteristic parameters of the output pulse waveform after the standardization are extracted, and the first spectral line drift relationship is determined based on a fitting method or a list method; the first experiment is to place the scintillator detector inside a temperature control box, and place the light guide, LED, optical attenuator, electronic system and host computer outside the temperature control box;

[0020] The second experiment is carried out by the host computer to obtain the baseline height of the output pulse waveform of the current-type preamplifier at different temperatures and the spectral line drift corresponding to each baseline height, and the second spectral line drift relationship is determined based on the fitting method or the list method; the second experiment is to place the electronic system inside the temperature control box, and place the scintillator detector, light guide, LED, light attenuator and host computer outside the temperature control box;

[0021] The third experiment is carried out by the host computer to obtain the output pulse waveform, baseline height and spectral line drift at different temperatures; the third spectral line drift relationship is determined based on the fitting method or the list method; the third experiment is to place the scintillator detector, light guide, LED, light attenuator, and electronic system inside the temperature control box, and the host computer is placed outside the temperature control box;

[0022] The first experiment, the second experiment and the third experiment are respectively performed by the host computer to obtain the first spectral line drift, the second spectral line drift and the third spectral line drift at different temperatures, and the fourth spectral line drift relationship is determined based on the fitting method or the list method.

[0023] Optionally, the scintillator in the scintillator detector is a NaI crystal.

[0024] Optionally, the optical attenuator is a light absorption type attenuator, a light reflection type attenuator or a polarization type attenuator.

[0025] Optionally, the photoelectric converter is a photomultiplier tube or a silicon photomultiplier tube.

[0026] Optionally, the preprocessing is a standardization process.

[0027] In a second aspect, the present application provides a scintillator gamma spectrometer LED spectrum stabilization method based on a current type spectrometer based on the above-mentioned scintillator gamma spectrometer LED spectrum stabilization system based on a current type spectrometer, comprising:

[0028] The first experiment is carried out by a host computer to obtain the output pulse waveform and spectral line drift of the current-type preamplifier at different temperatures, and the output pulse waveform is standardized, and the pulse characteristic parameters of the output pulse waveform after the standardization are extracted, and the first spectral line drift relationship is determined based on a fitting method or a list method; the first experiment is to place the scintillator detector inside a temperature control box, and place the light guide, LED, optical attenuator, electronic system and host computer outside the temperature control box;

[0029] The second experiment is carried out by the host computer to obtain the baseline height of the output pulse waveform of the current-type preamplifier at different temperatures and the spectral line drift corresponding to each baseline height, and the second spectral line drift relationship is determined based on the fitting method or the list method; the second experiment is to place the electronic system inside the temperature control box, and place the scintillator detector, light guide, LED, light attenuator and host computer outside the temperature control box;

[0030] The third experiment is carried out by the host computer to obtain the output pulse waveform, baseline height and spectral line drift at different temperatures; the third spectral line drift relationship is determined based on the fitting method or the list method; the third experiment is to place the scintillator detector, light guide, LED, light attenuator, and electronic system inside the temperature control box, and the host computer is placed outside the temperature control box;

[0031] The first experiment, the second experiment and the third experiment are respectively performed by the host computer to obtain the first spectral line drift, the second spectral line drift and the third spectral line drift at different temperatures, and the fourth spectral line drift relationship is determined based on a fitting method or a list method;

[0032] Determine the final spectral line drift channel number according to the pulse characteristic parameter, the baseline height and the third spectral line drift relationship; perform spectral line correction processing according to the final spectral line drift channel number; the third spectral line drift relationship is a mapping relationship between the pulse characteristic parameter, the baseline height and the spectral line drift;

[0033] Or, determine the number of spectral line drift channels corresponding to the scintillator according to the pulse characteristic parameter and the first spectral line drift relationship; determine the number of spectral line drift channels corresponding to the electronic system according to the baseline height and the second spectral line drift relationship; determine the number of co-acting spectral line drift channels according to the number of spectral line drift channels corresponding to the scintillator, the number of spectral line drift channels corresponding to the electronic system and the fourth spectral line drift relationship; determine the number of co-acting spectral line drift channels as the final number of spectral line drift channels; perform spectral line correction processing according to the final number of spectral line drift channels; the number of co-acting spectral line drift channels is the number of spectral line drift channels caused by the combined action of the scintillator and the electronic system; the first spectral line drift relationship is the mapping relationship between the pulse characteristic parameter and the spectral line drift; the second spectral line drift relationship is the mapping relationship between the baseline height and the spectral line drift; the fourth spectral line drift relationship is the mapping relationship between the first spectral line drift, the second spectral line drift and the third spectral line drift; the first spectral line drift is determined based on the first spectral line drift relationship; the second spectral line drift is determined based on the second spectral line drift relationship; the third spectral line drift is determined based on the third spectral line drift relationship;

[0034] Or, the number of spectral line drift channels corresponding to the scintillator is determined according to the pulse characteristic parameters and the first spectral line drift relationship; the number of spectral line drift channels corresponding to the electronic system is determined according to the baseline height and the second spectral line drift relationship; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system constitute the final number of spectral line drift channels; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system are used respectively to perform spectral line correction processing.

[0035] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0036] The present application provides a scintillator gamma spectrometer LED spectrum stabilization system and method based on a current-type spectrometer. It does not have a temperature acquisition system and can more accurately reflect the characteristics of the scintillator detector with spectral line drift, thereby achieving a more accurate spectrum stabilization effect. At the same time, it reduces the complexity of the system and solves the problems of large errors and high system complexity of the existing temperature-compensated scintillator spectrum stabilization method. The present application only considers the change of the baseline. After the spectrometer restores the baseline through a baseline subtraction algorithm, the original signal pulse can be correctly extracted. Therefore, the dead time is close to zero, which can effectively reduce the count rate loss in the spectrum stabilization process, improve the measurement accuracy, and solve the problem of dead time in the existing LED spectrum stabilization method. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 This is a structural schematic diagram of a scintillator gamma spectrometer LED spectrum stabilization system based on a current-type spectrometer in one embodiment of the present application;

[0039] Figure 2 A schematic diagram of output waveforms of NaI crystals at different temperatures provided in an embodiment of the present application;

[0040] Figure 3 A schematic diagram of a baseline and spectrum without adding an LED signal provided in an embodiment of the present application;

[0041] Figure 4 A schematic diagram of the baseline and spectrum line when using LED spectrum stabilization provided in an embodiment of the present application;

[0042] Figure 5 A schematic diagram of a first experimental scheme provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] The method for compensating for the temperature drift of the scintillator itself is as follows: first, the temperature of the scintillator detector is adjusted in a temperature control box, and the relationship curve between the spectral line drift and the scintillator surface temperature at different temperatures is measured, and a fitting curve formula or list is formed and stored in the instrument. In the actual measurement process, the surface temperature of the scintillator detector is measured using a temperature sensor, and then the influence of the spectral line drift caused by the scintillator temperature change is determined based on the relationship curve or table between the temperature and spectral line drift obtained experimentally.

[0045] The method of LED spectrum stabilization for the circuit behind the scintillator is as follows: the LED is placed close to the scintillator so that the output light of the LED and the fluorescence emitted by the scintillator can irradiate the photomultiplier tube to form an energy spectrum. The LED is driven by a constant current source circuit so that the LED emits a pulse beam of a specific intensity and irradiates it onto the PMT. The pulse current is output by the PMT, and the artificially introduced LED characteristic reference peak is obtained through the gamma spectrometer. The intensity and peak position of the LED characteristic reference peak can be adjusted by adjusting the frequency, pulse width and constant current value of the output pulse signal, so that the LED reference peak is far away from the energy range to be measured, and the energy peak with appropriate intensity can be quickly obtained. The use of the LED reference peak can eliminate the temperature effect of the PMT and all the electronics at the back end, and achieve rapid spectrum stabilization.

[0046] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0047] In an exemplary embodiment, Figure 1 As shown, a scintillator gamma spectrometer LED spectrum stabilization system based on a current-type spectrometer is provided, including a scintillator detector, a light guide, an LED, an optical attenuator, an electronics system and a host computer; the electronics system includes a photoelectric converter, a current-type preamplifier and a current-type digital pulse processor.

[0048] Among them, the scintillator detector is used to generate fluorescence signals.

[0049] The present application adds a layer of light guide between the scintillator detector and the photoelectric converter, and opens a hole in the light guide, so that there is a hole area on the light guide, and an LED and a light attenuator are arranged in the hole area; the light attenuator is used to attenuate the LED light signal generated by the LED to obtain an attenuated light signal. It should be noted that the overall diameter of the LED and the light attenuator is relatively small.

[0050] The light output of scintillators is greatly affected by temperature. For example, the scintillator in a scintillator detector can be a NaI crystal. The maximum light output temperature range of NaI crystal is between 20℃ and 30℃. At a temperature of -40℃, its light output will drop to about 70% of the maximum light output, and at a high temperature of 60℃, the light output will drop to about 95% of the maximum light output. At the same time, temperature will also affect the luminescence decay time of the scintillator crystal. The luminescence decay time constant of the crystal gradually increases as the temperature decreases. When the temperature drops to -40℃, its luminescence decay time will be as long as 700ns. In the case of narrow pulse shaping, the change in luminescence decay time is the main reason for spectral line drift. Figure 2 The output waveforms (current pulse signals) of gamma rays after passing through NaI crystal and photomultiplier tube at different temperatures are compared. It can be clearly seen that the waveforms at different temperatures are very different. At high temperatures, the waveform is narrow and the exponential tail is small; at low temperatures, the exponential tail becomes significantly longer.

[0051] This application uses LED to emit a stable weak light source to raise the baseline of the signal, and stabilizes the spectrum by analyzing the signal baseline. Since this spectrum stabilization method does not generate a pulse signal, it does not affect the useful signal luminescence (fluorescence signal) of the scintillator, so there is no measurement dead time.

[0052] It should be noted that when selecting LEDs, the LED light must be stable and well matched with the photoelectric converter. Therefore, the most sensitive wavelength of the photoelectric converter must be consistent with the maximum wavelength of the LED.

[0053] Before the LED light is turned on, the original signal collected by the current spectrometer is as follows: Figure 3 As shown, the scintillator signal pulse is superimposed on a smaller baseline 1 potential. When LED spectrum stabilization is used, the signal is as follows Figure 4 As shown, at this time, the LED light is on, the signal 0 potential remains unchanged, but the signal and the baseline are raised together. Under the condition that the LED luminous intensity is known to be constant, the gain change of the photomultiplier tube and the spectrometer electronics can be obtained by analyzing the amplitude of the baseline increase, and the purpose of spectrum stabilization can be achieved through correction. Since it is only a change in the baseline, the original signal pulse can be correctly extracted after the baseline is restored by the baseline subtraction algorithm, so the dead time is close to zero, which can effectively reduce the count rate loss in the spectrum stabilization process and improve the measurement accuracy.

[0054] In another exemplary embodiment of the present application, the optical attenuator is a light absorption type attenuator, a light reflection type attenuator or a polarization type attenuator. The LED luminous intensity under normal working conditions will cause the photomultiplier tube to be in a light saturation state, so it is necessary to take light attenuation treatment on the LED. The application requirements of light attenuation may be different under different conditions. According to the different physical mechanisms of attenuation, the optical attenuator can be divided into a light absorption type attenuator, a light reflection type attenuator and a polarization type attenuator. Specifically, a neutral polyvinyl chloride (PVC) optical attenuation sheet can be selected, which is a light absorption type attenuator and can be used for the attenuation of various light. The refractive index of the transparent PVC optical attenuation sheet is similar to that of air, so all colored light can pass through, and the addition of corresponding dyes can realize the absorption of light to achieve the purpose of light attenuation.

[0055] The photoelectric converter is used to perform photoelectric conversion on the fluorescence signal and the attenuated light signal to obtain a current signal. The type of photomultiplier tube is selected according to the actual situation. The photoelectric converter can be a photomultiplier tube (PMT) or a silicon photomultiplier tube (SiPM).

[0056] The current type preamplifier is used to amplify the current signal to obtain an amplified current pulse signal.

[0057] The current type digital pulse processor is used to extract the baseline height of the amplified current pulse signal and remove the baseline in the amplified current pulse signal based on the baseline height to obtain the current signal pulse.

[0058] The host computer is used to: pre-process the current signal pulse to obtain the pre-processed current signal pulse; extract the characteristics of the pre-processed current signal pulse to obtain the pulse characteristic parameters; determine the final spectral line drift channel number according to the pulse characteristic parameters and the baseline height, and perform spectral line correction processing according to the final spectral line drift channel number. The pre-processing is a standardization process.

[0059] Conventional spectrometers use voltage-type preamplifiers, whose output signal is the integral of the current signal pulse output by the photoelectric converter, and cannot maintain the original pulse shape of the photoelectric converter output. The present application uses a current-type preamplifier, which can well maintain the current signal pulse output by the photoelectric converter, so that the current signal pulse is used for processing in the current-type pulse processor, that is, using Figure 2 The graph shown determines the relationship between the output waveform and temperature as well as the spectrum line drift, thereby achieving the purpose of spectrum stabilization.

[0060] In another exemplary embodiment of the present application, the scintillator gamma spectrometer LED spectrum stabilization system based on the current type spectrometer further includes a spectrum line drift relationship determination module; the spectrum line drift relationship determination module is used to:

[0061] The first experiment is carried out by a host computer to obtain the output pulse waveform and spectral line drift of the current-type preamplifier at different temperatures, and the output pulse waveform is standardized, and the pulse characteristic parameters of the output pulse waveform after the standardization are extracted, and the first spectral line drift relationship is determined based on a fitting method or a list method; the first experiment is to place the scintillator detector inside a temperature control box, and place the light guide, LED, optical attenuator, electronic system and host computer outside the temperature control box;

[0062] The second experiment is carried out by the host computer to obtain the baseline height of the output pulse waveform of the current-type preamplifier at different temperatures and the spectral line drift corresponding to each baseline height, and the second spectral line drift relationship is determined based on the fitting method or the list method; the second experiment is to place the electronic system inside the temperature control box, and place the scintillator detector, light guide, LED, light attenuator and host computer outside the temperature control box;

[0063] The third experiment is carried out by the host computer to obtain the output pulse waveform, baseline height and spectral line drift at different temperatures; the third spectral line drift relationship is determined based on the fitting method or the list method; the third experiment is to place the scintillator detector, light guide, LED, light attenuator, and electronic system inside the temperature control box, and the host computer is placed outside the temperature control box;

[0064] The first experiment, the second experiment and the third experiment are respectively performed by the host computer to obtain the first spectral line drift, the second spectral line drift and the third spectral line drift at different temperatures, and the fourth spectral line drift relationship is determined based on the fitting method or the list method.

[0065] A series of experiments were conducted using a gamma standard radiation source and a temperature control box to determine the relationship between the waveform of the current-mode preamplifier output pulse and the spectral line drift. Figure 5 shown. Figure 5 The high-voltage preamplifier in the figure refers to the high-voltage module and the preamplifier module. The high-voltage module is used to power the preamplifier module, and the preamplifier module refers to the current type preamplifier.

[0066] The waveforms and spectral line drifts of a series of current-type preamplifier output pulses at different temperatures are obtained through experiments, and then the pulse characteristic parameters after standardization are extracted on the host computer. The selection of pulse waveform characteristic parameters can refer to the method used in the pulse shape discrimination (PSD) algorithm to characterize pulse characteristics, such as pulse decline gradient, pulse area ratio method and other methods, that is, the pulse characteristic parameters include pulse decline gradient and / or pulse area ratio. Then, through fitting or tabulation methods, a one-to-one mapping relationship is established between the characteristic parameters of the pulses obtained at various temperatures and the corresponding spectral line drifts. This relationship is written into the current-type digital pulse processor, and the pulse characteristic extraction method is implemented in the current-type digital pulse processor. This application names the table of this relationship as the first spectral line drift relationship.

[0067] The second experimental plan is similar Figure 5 The hardware platform has been equipped with an LED spectrum stabilization system. It only places the photoelectric conversion device and current preamplifier and other circuits in a temperature control box, and the other parts are placed at room temperature. Adjust the temperature of the temperature control box to obtain the baseline height of the waveform of the pulse output by the current preamplifier under different temperature conditions, as well as the corresponding spectral line drift. The upper computer analyzes the relationship between the spectral line drift corresponding to different baseline heights, forms a formula or table, and writes this mapping relationship into the current-type digital pulse processor. This application names the table of this relationship as the second spectral line drift relationship.

[0068] The third experimental plan is similar Figure 5 The hardware platform has been equipped with an LED spectrum stabilization system. All devices except the host computer are placed in a temperature control box, the temperature is adjusted for measurement, and then analyzed on the host computer to obtain the pulse shape, baseline height and spectral line drift at different temperatures.

[0069] Based on the pulse shape, baseline height and spectral line drift at different temperatures obtained in the third experiment above, the relationship between the pulse waveform characteristic parameters, baseline height and spectral line drift can be directly established, and then this mapping relationship is written into the current-type digital pulse processor. This application names the table of this relationship as the third spectral line drift relationship.

[0070] Based on the pulse shape, baseline height and spectral line drift at different temperatures obtained in the third experiment, a relationship curve between the spectral line drift caused by the two parts and the overall spectral line drift at different temperatures can also be established, that is, at a certain temperature, the first spectral line drift P1 at the temperature is obtained by the first experiment corresponding to the first spectral line drift relationship, the second spectral line drift P2 at the temperature is obtained by the second experiment corresponding to the second spectral line drift relationship, and the third spectral line drift P3 at the temperature is obtained by the third experiment corresponding to the third spectral line drift relationship. Then, the relationship between P1, P2 and P3 is determined on the host computer by fitting method or list method, and this relationship is written into the current-type digital pulse processor. This application names the table of this relationship as the fourth spectral line drift relationship.

[0071] In another exemplary embodiment of the present application, the following method may be adopted: instead of performing the above experiment, the amplification gain is adjusted separately according to the spectral line drift caused by the scintillator and the electronic system.

[0072] In one example of the present application, in determining the final spectral line drift channel number according to the pulse characteristic parameter and the baseline height, and performing spectral line correction processing according to the final spectral line drift channel number, the host computer is used to:

[0073] Determine the final spectral line drift channel number according to the pulse characteristic parameter, the baseline height and the third spectral line drift relationship; perform spectral line correction processing according to the final spectral line drift channel number; the third spectral line drift relationship is a mapping relationship between the pulse characteristic parameter, the baseline height and the spectral line drift;

[0074] Or, determine the number of spectral line drift channels corresponding to the scintillator according to the pulse characteristic parameter and the first spectral line drift relationship; determine the number of spectral line drift channels corresponding to the electronic system according to the baseline height and the second spectral line drift relationship; determine the number of co-acting spectral line drift channels according to the number of spectral line drift channels corresponding to the scintillator, the number of spectral line drift channels corresponding to the electronic system and the fourth spectral line drift relationship; determine the number of co-acting spectral line drift channels as the final number of spectral line drift channels; perform spectral line correction processing according to the final number of spectral line drift channels; the number of co-acting spectral line drift channels is the number of spectral line drift channels caused by the combined action of the scintillator and the electronic system; the first spectral line drift relationship is the mapping relationship between the pulse characteristic parameter and the spectral line drift; the second spectral line drift relationship is the mapping relationship between the baseline height and the spectral line drift; the fourth spectral line drift relationship is the mapping relationship between the first spectral line drift, the second spectral line drift and the third spectral line drift; the first spectral line drift is determined based on the first spectral line drift relationship; the second spectral line drift is determined based on the second spectral line drift relationship; the third spectral line drift is determined based on the third spectral line drift relationship;

[0075] Or, the number of spectral line drift channels corresponding to the scintillator is determined according to the pulse characteristic parameters and the first spectral line drift relationship; the number of spectral line drift channels corresponding to the electronic system is determined according to the baseline height and the second spectral line drift relationship; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system constitute the final number of spectral line drift channels; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system are used respectively to perform spectral line correction processing.

[0076] The spectrum stabilization strategy in actual use is as follows:

[0077] Hardware components such as Figure 1 As shown, in the actual test process, when spectrum stabilization operation is required, turn on the LED light, and the pulse signal of the current preamplifier enters the current type digital pulse processor after passing through the AD converter, extract the baseline of the signal of the current preamplifier, and then remove the baseline of the signal to obtain the signal pulse, and then standardize the signal, and then extract the characteristic parameters of the standardized pulse, and then perform correction processing according to any of the following methods:

[0078] 1) According to the pulse characteristic parameters and the baseline height, the corresponding spectral line drift channel number in the third spectral line drift relationship is found, and then the spectral line drift correction is performed from the hardware (gain multiple) or software aspects.

[0079] 2) According to the pulse characteristic parameters, the first spectral line drift relationship is searched to know the spectral line drift channel number P1 caused by the scintillator. According to the baseline height, the second spectral line drift relationship is searched to know the spectral line drift channel number P2 caused by the electronic system. Then the fourth spectral line drift relationship is searched to know the spectral line drift channel number caused by the combined effect of the two. Then the spectral line drift correction is performed from the hardware (gain multiple) or software aspects.

[0080] 3) The third method is to correct the spectral line drifts obtained from the first spectral line drift relationship and the second spectral line drift relationship respectively, assuming that the spectral line drifts caused by the two are simply superimposed.

[0081] In another exemplary embodiment of the present application, another strategy is adopted. For the scintillator, the aforementioned method is still used, but for the LED spectrum stabilization, the LED pulse light emission method is adopted, that is, a narrow LED pulse is used to drive the LED to emit light. The light emitted by the LED is a short pulse light, similar to the scintillator light emission. After the LED spectrum stabilization is turned on, a large amount of signal is generated in a short time, forming an LED peak on the energy spectrum, and then using this LED peak to stabilize the spectrum. The combination of the two forms the second scheme of the scintillator gamma spectrometer LED spectrum stabilization method based on the current type spectrometer.

[0082] Based on the same inventive concept, the embodiment of the present application also provides a scintillator gamma spectrometer LED spectrum stabilization method based on a current spectrometer for realizing the above-mentioned scintillator gamma spectrometer LED spectrum stabilization system based on a current spectrometer. The implementation scheme for solving the problem provided by this method is similar to the implementation scheme recorded in the above-mentioned system, so the specific limitations in one or more embodiments of the scintillator gamma spectrometer LED spectrum stabilization method based on a current spectrometer provided below can refer to the limitations of the scintillator gamma spectrometer LED spectrum stabilization system based on a current spectrometer above, and will not be repeated here.

[0083] In an exemplary embodiment, a scintillator gamma spectrometer LED spectrum stabilization method based on a current-type spectrometer is provided, comprising:

[0084] The first experiment is carried out by a host computer to obtain the output pulse waveform and spectral line drift of the current-type preamplifier at different temperatures, and the output pulse waveform is standardized, and the pulse characteristic parameters of the output pulse waveform after the standardization are extracted, and the first spectral line drift relationship is determined based on a fitting method or a list method; the first experiment is to place the scintillator detector inside a temperature control box, and place the light guide, LED, optical attenuator, electronic system and host computer outside the temperature control box;

[0085] The second experiment is carried out by the host computer to obtain the baseline height of the output pulse waveform of the current-type preamplifier at different temperatures and the spectral line drift corresponding to each baseline height, and the second spectral line drift relationship is determined based on the fitting method or the list method; the second experiment is to place the electronic system inside the temperature control box, and place the scintillator detector, light guide, LED, light attenuator and host computer outside the temperature control box;

[0086] The third experiment is carried out by the host computer to obtain the output pulse waveform, baseline height and spectral line drift at different temperatures; the third spectral line drift relationship is determined based on the fitting method or the list method; the third experiment is to place the scintillator detector, light guide, LED, light attenuator, and electronic system inside the temperature control box, and the host computer is placed outside the temperature control box;

[0087] The first experiment, the second experiment and the third experiment are respectively performed by the host computer to obtain the first spectral line drift, the second spectral line drift and the third spectral line drift at different temperatures, and the fourth spectral line drift relationship is determined based on a fitting method or a list method;

[0088] Determine the final spectral line drift channel number according to the pulse characteristic parameter, the baseline height and the third spectral line drift relationship; perform spectral line correction processing according to the final spectral line drift channel number; the third spectral line drift relationship is a mapping relationship between the pulse characteristic parameter, the baseline height and the spectral line drift;

[0089] Or, determine the number of spectral line drift channels corresponding to the scintillator according to the pulse characteristic parameter and the first spectral line drift relationship; determine the number of spectral line drift channels corresponding to the electronic system according to the baseline height and the second spectral line drift relationship; determine the number of co-acting spectral line drift channels according to the number of spectral line drift channels corresponding to the scintillator, the number of spectral line drift channels corresponding to the electronic system and the fourth spectral line drift relationship; determine the number of co-acting spectral line drift channels as the final number of spectral line drift channels; perform spectral line correction processing according to the final number of spectral line drift channels; the number of co-acting spectral line drift channels is the number of spectral line drift channels caused by the combined action of the scintillator and the electronic system; the first spectral line drift relationship is the mapping relationship between the pulse characteristic parameter and the spectral line drift; the second spectral line drift relationship is the mapping relationship between the baseline height and the spectral line drift; the fourth spectral line drift relationship is the mapping relationship between the first spectral line drift, the second spectral line drift and the third spectral line drift; the first spectral line drift is determined based on the first spectral line drift relationship; the second spectral line drift is determined based on the second spectral line drift relationship; the third spectral line drift is determined based on the third spectral line drift relationship;

[0090] Or, the number of spectral line drift channels corresponding to the scintillator is determined according to the pulse characteristic parameters and the first spectral line drift relationship; the number of spectral line drift channels corresponding to the electronic system is determined according to the baseline height and the second spectral line drift relationship; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system constitute the final number of spectral line drift channels; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system are used respectively to perform spectral line correction processing.

[0091] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A scintillator gamma spectrometer LED spectrum stabilization system based on a current type spectrometer, characterized in that: The scintillator gamma spectrometer LED spectrum stabilization system based on the current type spectrometer includes a scintillator detector, a light guide, an LED, a light attenuator, an electronics system and a host computer; the electronics system includes a photoelectric converter, a current type preamplifier and a current type digital pulse processor; The scintillator detector is used to generate a fluorescence signal; There is a hole area on the light guide, and an LED and a light attenuator are arranged in the hole area; the light attenuator is used to attenuate the LED light signal generated by the LED to obtain an attenuated light signal; The photoelectric converter is used to: perform photoelectric conversion on the fluorescence signal and the attenuated light signal to obtain a current signal; The current type preamplifier is used to: amplify the current signal to obtain an amplified current pulse signal; The current-type digital pulse processor is used to: extract the baseline height of the amplified current pulse signal, and remove the baseline in the amplified current pulse signal based on the baseline height to obtain a current signal pulse; The host computer is used to: pre-process the current signal pulse to obtain a pre-processed current signal pulse; Extracting features of the preprocessed current signal pulse to obtain pulse feature parameters; The final spectral line drift channel number is determined according to the pulse characteristic parameter and the baseline height, and the spectral line correction processing is performed according to the final spectral line drift channel number.

2. The scintillator gamma spectrometer LED spectrum stabilization system based on current type spectrometer according to claim 1, characterized in that: In terms of determining the final spectral line drift channel number according to the pulse characteristic parameter and the baseline height, and performing spectral line correction processing according to the final spectral line drift channel number, the host computer is used to: Determine the final spectral line drift channel number according to the pulse characteristic parameter, the baseline height and the third spectral line drift relationship; perform spectral line correction processing according to the final spectral line drift channel number; the third spectral line drift relationship is a mapping relationship between the pulse characteristic parameter, the baseline height and the spectral line drift; Or, determine the number of spectral line drift channels corresponding to the scintillator according to the pulse characteristic parameter and the first spectral line drift relationship; determine the number of spectral line drift channels corresponding to the electronic system according to the baseline height and the second spectral line drift relationship; determine the number of co-acting spectral line drift channels according to the number of spectral line drift channels corresponding to the scintillator, the number of spectral line drift channels corresponding to the electronic system and the fourth spectral line drift relationship; determine the number of co-acting spectral line drift channels as the final number of spectral line drift channels; perform spectral line correction processing according to the final number of spectral line drift channels; the number of co-acting spectral line drift channels is the number of spectral line drift channels caused by the combined action of the scintillator and the electronic system; the first spectral line drift relationship is the mapping relationship between the pulse characteristic parameter and the spectral line drift; the second spectral line drift relationship is the mapping relationship between the baseline height and the spectral line drift; the fourth spectral line drift relationship is the mapping relationship between the first spectral line drift, the second spectral line drift and the third spectral line drift; the first spectral line drift is determined based on the first spectral line drift relationship; the second spectral line drift is determined based on the second spectral line drift relationship; the third spectral line drift is determined based on the third spectral line drift relationship; Or, the number of spectral line drift channels corresponding to the scintillator is determined according to the pulse characteristic parameters and the first spectral line drift relationship; the number of spectral line drift channels corresponding to the electronic system is determined according to the baseline height and the second spectral line drift relationship; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system constitute the final number of spectral line drift channels; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system are used respectively to perform spectral line correction processing.

3. The scintillator gamma spectrometer LED spectrum stabilization system based on current type spectrometer according to claim 1, characterized in that: The scintillator gamma spectrometer LED spectrum stabilization system based on the current type spectrometer further includes a spectrum line drift relationship determination module; the spectrum line drift relationship determination module is used to: The first experiment is carried out by a host computer to obtain the output pulse waveform and spectral line drift of the current-type preamplifier at different temperatures, and the output pulse waveform is standardized, and the pulse characteristic parameters of the output pulse waveform after the standardization are extracted, and the first spectral line drift relationship is determined based on a fitting method or a list method; the first experiment is to place the scintillator detector inside a temperature control box, and place the light guide, LED, optical attenuator, electronic system and host computer outside the temperature control box; The second experiment is carried out by the host computer to obtain the baseline height of the output pulse waveform of the current-type preamplifier at different temperatures and the spectral line drift corresponding to each baseline height, and the second spectral line drift relationship is determined based on the fitting method or the list method; the second experiment is to place the electronic system inside the temperature control box, and place the scintillator detector, light guide, LED, light attenuator and host computer outside the temperature control box; The third experiment is carried out by the host computer to obtain the output pulse waveform, baseline height and spectral line drift at different temperatures; the third spectral line drift relationship is determined based on the fitting method or the list method; the third experiment is to place the scintillator detector, light guide, LED, light attenuator, and electronic system inside the temperature control box, and the host computer is placed outside the temperature control box; The first experiment, the second experiment and the third experiment are respectively performed by the host computer to obtain the first spectral line drift, the second spectral line drift and the third spectral line drift at different temperatures, and the fourth spectral line drift relationship is determined based on the fitting method or the list method.

4. The scintillator gamma spectrometer LED spectrum stabilization system based on current type spectrometer according to claim 1, characterized in that: The scintillator in the scintillator detector is NaI crystal.

5. The scintillator gamma spectrometer LED spectrum stabilization system based on current type spectrometer according to claim 1, characterized in that: The optical attenuator is a light absorption type attenuator, a light reflection type attenuator or a polarization type attenuator.

6. The scintillator gamma spectrometer LED spectrum stabilization system based on current type spectrometer according to claim 1, characterized in that: The photoelectric converter is a photomultiplier tube or a silicon photomultiplier tube.

7. The scintillator gamma spectrometer LED spectrum stabilization system based on current type spectrometer according to claim 1, characterized in that: The preprocessing is a standardization process.

8. A scintillator gamma spectrometer LED spectrum stabilization method based on a current type spectrometer based on the scintillator gamma spectrometer LED spectrum stabilization system based on a current type spectrometer according to claim 1, characterized in that: The scintillator gamma spectrometer LED spectrum stabilization method based on the current type spectrometer comprises: The first experiment is carried out by a host computer to obtain the output pulse waveform and spectral line drift of the current-type preamplifier at different temperatures, and the output pulse waveform is standardized, and the pulse characteristic parameters of the output pulse waveform after the standardization are extracted, and the first spectral line drift relationship is determined based on a fitting method or a list method; the first experiment is to place the scintillator detector inside a temperature control box, and place the light guide, LED, optical attenuator, electronic system and host computer outside the temperature control box; The second experiment is carried out by the host computer to obtain the baseline height of the output pulse waveform of the current-type preamplifier at different temperatures and the spectral line drift corresponding to each baseline height, and the second spectral line drift relationship is determined based on the fitting method or the list method; the second experiment is to place the electronic system inside the temperature control box, and place the scintillator detector, light guide, LED, light attenuator and host computer outside the temperature control box; The third experiment is carried out by the host computer to obtain the output pulse waveform, baseline height and spectral line drift at different temperatures; the third spectral line drift relationship is determined based on the fitting method or the list method; the third experiment is to place the scintillator detector, light guide, LED, light attenuator, and electronic system inside the temperature control box, and the host computer is placed outside the temperature control box; The first experiment, the second experiment and the third experiment are respectively performed by the host computer to obtain the first spectral line drift, the second spectral line drift and the third spectral line drift at different temperatures, and the fourth spectral line drift relationship is determined based on a fitting method or a list method; Determine the final spectral line drift channel number according to the pulse characteristic parameter, the baseline height and the third spectral line drift relationship; perform spectral line correction processing according to the final spectral line drift channel number; the third spectral line drift relationship is a mapping relationship between the pulse characteristic parameter, the baseline height and the spectral line drift; Or, determine the number of spectral line drift channels corresponding to the scintillator according to the pulse characteristic parameter and the first spectral line drift relationship; determine the number of spectral line drift channels corresponding to the electronic system according to the baseline height and the second spectral line drift relationship; determine the number of co-acting spectral line drift channels according to the number of spectral line drift channels corresponding to the scintillator, the number of spectral line drift channels corresponding to the electronic system and the fourth spectral line drift relationship; determine the number of co-acting spectral line drift channels as the final number of spectral line drift channels; perform spectral line correction processing according to the final number of spectral line drift channels; the number of co-acting spectral line drift channels is the number of spectral line drift channels caused by the combined action of the scintillator and the electronic system; the first spectral line drift relationship is the mapping relationship between the pulse characteristic parameter and the spectral line drift; the second spectral line drift relationship is the mapping relationship between the baseline height and the spectral line drift; the fourth spectral line drift relationship is the mapping relationship between the first spectral line drift, the second spectral line drift and the third spectral line drift; the first spectral line drift is determined based on the first spectral line drift relationship; the second spectral line drift is determined based on the second spectral line drift relationship; the third spectral line drift is determined based on the third spectral line drift relationship; Or, the number of spectral line drift channels corresponding to the scintillator is determined according to the pulse characteristic parameters and the first spectral line drift relationship; the number of spectral line drift channels corresponding to the electronic system is determined according to the baseline height and the second spectral line drift relationship; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system constitute the final number of spectral line drift channels; the number of spectral line drift channels corresponding to the scintillator and the number of spectral line drift channels corresponding to the electronic system are used respectively to perform spectral line correction processing.

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