A discriminator threshold determination method

Abstract

The present application discloses a method for determining a discriminator threshold, comprising: obtaining a particle pulse amplitude spectrum and determining a threshold channel address; obtaining a candidate channel address value greater than the threshold channel address from the particle pulse amplitude spectrum; determining a target count rate based on the particle pulse amplitude spectrum and the candidate channel address value, obtaining a logic signal of a discriminator having different reference discrimination thresholds set, and determining a candidate count rate; and determining a reference discrimination threshold corresponding to a candidate count rate identical to the target count rate as the target discrimination threshold. In this manner, the target count rate is determined based on the particle pulse amplitude spectrum and the count values of the candidate channel address value, and the reference discrimination threshold corresponding to the candidate count rate identical to the target count rate is determined as the target discrimination threshold. This allows the discriminator to remove the logic signal formed by the noise signal based on the target discrimination threshold, thereby ensuring the accuracy of the nuclear radiation detector in detecting nuclear events.

Description

Technical Field

[0001] The present application relates to the technical field of nuclear radiation measurement, and in particular to a method for determining a discriminator threshold. Background Art

[0002] In the field of nuclear radiation technology, nuclear radiation detectors and nuclear electronics are typically used to convert nuclear signals into observable signals, such as voltage signals. During the actual use of nuclear radiation detectors, there is more or less electronic noise in the device itself and the external environment. Such electronic noise affects the measurement of nuclear radiation events.

[0003] In related technologies, in certain applications, when the pulse amplitude spectrum threshold cannot be passed, a discriminator can be used to eliminate the signal generated by electronic noise. However, since the discriminator threshold is generally set manually, if it is set improperly, the actual signal obtained may be mostly caused by electronic noise, or some nuclear events may be missed. Summary of the Invention

[0004] In order to solve the above technical problems, an embodiment of the present application provides a method for determining a discriminator threshold. The discrimination threshold determined by this method can accurately eliminate the influence of electronic noise when measuring corresponding nuclear events, thereby ensuring the accuracy of nuclear radiation detectors in detecting nuclear events.

[0005] The technical solution of the embodiment of the application is implemented as follows:

[0006] The present invention provides a method for determining a discriminator threshold, including:

[0007] Obtaining a particle pulse amplitude spectrum and determining a threshold channel address in the particle pulse amplitude spectrum;

[0008] Obtaining at least one candidate channel address value greater than a threshold channel address from the particle pulse amplitude spectrum, wherein the voltage amplitude corresponding to the candidate channel address value is the amplitude of the voltage generated after the target particle is ionized, and the target particle is the particle generated after the nuclear reaction;

[0009] determining a target count rate based on the particle pulse amplitude spectrum and at least one candidate channel address value, wherein the target count rate represents the number of nuclear reactions that generate the target particles per unit time;

[0010] Acquire each logic signal and determine the candidate count rate corresponding to each logic signal, each logic signal being obtained by discriminating a mixed analog voltage signal formed by target particle ionization and electronic noise when the discriminator is set to different reference discrimination thresholds;

[0011] A reference discrimination threshold corresponding to the candidate count rate that is the same as the target count rate is determined as the target discrimination threshold.

[0012] The present application provides a method for determining a discriminator threshold. Using this technical solution, first, a particle pulse amplitude spectrum is obtained to determine a threshold channel address in the particle pulse amplitude spectrum. Then, at least one candidate channel address value greater than the threshold channel address is obtained from the particle pulse amplitude spectrum. The voltage amplitude corresponding to the candidate channel address value is the amplitude of the voltage generated after the ionization of the target particle, which is a particle produced after a nuclear reaction. Next, a target count rate is determined based on the particle pulse amplitude spectrum and the at least one candidate channel address value. Various logic signals are obtained and the candidate count rates corresponding to each logic signal are determined. Finally, a reference discrimination threshold corresponding to the candidate count rate identical to the target count rate is determined as the target discrimination threshold. In this manner, the target count rate is determined based on the particle pulse amplitude spectrum and the count values of the at least one candidate channel address value, and the reference discrimination threshold corresponding to the candidate count rate identical to the target count rate is determined as the target discrimination threshold. This allows the discriminator to remove logic signals generated by noise signals based on the target discrimination threshold, thereby ensuring the accuracy of nuclear radiation detectors in detecting nuclear events. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 An electronic block diagram for measuring thermal neutron time-of-flight spectrum provided in an embodiment of the present application;

[0014] Figure 2 A schematic diagram of a pulse amplitude spectrum corresponding to a logic signal output from a discriminator provided in an embodiment of the present application;

[0015] Figure 3 A schematic diagram of a waveform of a logic signal output from a discriminator provided in an embodiment of the present application;

[0016] Figure 4 A flowchart of a threshold determination method provided in an embodiment of the present application;

[0017] Figure 5 A schematic diagram of a particle pulse amplitude spectrum provided in an embodiment of the present application;

[0018] Figure 6 A flowchart of a method for accurately determining a discrimination threshold provided in an embodiment of the present application;

[0019] Figure 7 An electronic block diagram for measuring the alpha particle pulse amplitude spectrum provided in an embodiment of the present application;

[0020] Figure 8 A schematic diagram of the pulse amplitude spectrum corresponding to an alpha particle and its post-threshold details provided in an embodiment of the present application;

[0021] Figure 9An electronic block diagram for measuring the pulse amplitude spectrum of a logic signal output from a discriminator provided in an embodiment of the present application;

[0022] Figure 10 A pulse amplitude spectrum corresponding to a threshold scale of 0-60 provided in an embodiment of the present application;

[0023] Figure 11 A corresponding relationship diagram between count rate and discrimination threshold provided in an embodiment of the present application;

[0024] Figure 12 A detailed schematic diagram of the correspondence between count rate and discrimination threshold provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0026] In order to make the purpose, technical solutions and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limiting this application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] In the following description, reference is made to “some embodiments\other embodiments”, which describe a subset of all possible embodiments, but it can be understood that “some embodiments\other embodiments” may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0028] In the following description, the terms "first\second" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It is understandable that "first\second" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0029] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0030] The thermal neutron reference radiation field is one of the neutron radiation fields recommended internationally for determining the energy response of neutron measuring instruments. In order to ensure that the values of neutron measurements are mutually recognized among countries, the Third Division of the International Consultative Committee on Ionizing Radiation (CCRI(III)) will periodically organize metrological technical institutions in various countries to participate in thermal neutron comparisons. Since thermal neutrons are produced after neutrons reach thermal equilibrium with the surrounding medium, there are many instruments used to measure thermal neutrons in the field of radiation protection, and there is a great demand for traceability of the values of related thermal neutron measuring instruments. With the vigorous development of nuclear power plants and the widespread application of nuclear technology, the demand for new radiation protection materials has also increased accordingly, and the protective performance of the materials must be tested under the thermal neutron field. With the expansion of thermal neutron applications, the research and development of various thermal neutron detectors has become increasingly active, and the performance improvement of detectors also requires the technical support provided by the thermal neutron field.

[0031] During the development of the thermal neutron field, the time-of-flight method is required to measure the thermal neutron energy spectrum. The corresponding electronic block diagram is as follows: Figure 1 As shown. Figure 1 As shown, the electronic block diagram mainly includes a He-3 detector 101, a preamplifier 102, a main amplifier 103, a discriminator 104, a photoelectric system 105, a time-to-amplitude converter 106, a multi-channel analyzer 107, and a data acquisition system 108. In the He-3 detector 101, He-3 reacts with neutrons to produce protons and tritium. After ionization, the protons and tritium generate an electrical signal. This electrical signal is amplified by the preamplifier 102 and the main amplifier 103, and then input into the discriminator 104. The discriminator 104 discriminates the signal to obtain a logic signal, which is input into the time-to-amplitude converter 106 as a signal to stop neutron flight. On the other hand, the photoelectric system 105 inputs the photoelectric signal serving as the neutron take-off time into the time-to-amplitude converter 106. The time-to-amplitude converter 106 converts the time difference between the neutron take-off time and the neutron stop time into a voltage signal proportional to the time difference, and inputs the voltage signal into the multi-channel analyzer 107 and the data acquisition system 108 to obtain the neutron flight time spectrum.

[0032] When measuring neutron flight stop signals with a He-3 detector, due to the presence of noise signals such as electronic noise and gamma rays, the stop signal count rate from the discriminator is very high without setting a discrimination threshold. This is illustrated using a U-235 fission ionization chamber (uranium isotopes undergo spontaneous alpha decay, so an additional neutron source is not required). When the discriminator threshold is not set, the pulse amplitude spectrum obtained after measuring for 60 seconds is as follows: Figure 2 As shown. Figure 2 As can be seen, the counts coming out of the discriminator are very high at 2410308, with an average count rate of 40172s -1 , Figure 2There are only 574 counts because the positive signal from the discriminator Octec551 is a +5V logic signal, and its waveform is as follows Figure 3 As shown in the figure. Due to the presence of noise signals, when no discrimination threshold is set, the pulse amplitude spectrum obtained is not just the pulse amplitude spectrum corresponding to the alpha particle. That is, the pulse amplitude spectrum includes the voltage amplitude formed by the noise signal, which reduces the accuracy of the nuclear radiation detector in detecting nuclear events.

[0033] In response to the problems in the related art, an embodiment of the present application provides a method for determining a discriminator threshold. The discrimination threshold determined by this method can accurately eliminate the influence of electronic noise when measuring the corresponding nuclear event, thereby ensuring the accuracy of the nuclear radiation detector in detecting nuclear events.

[0034] The following describes a method for determining a discriminator threshold value provided by an embodiment of the present application. Figure 4 FIG. 1 is a flow chart of a method for determining a discriminator threshold value provided in an embodiment of the present application, the method comprising the following steps:

[0035] S101. Obtain a particle pulse amplitude spectrum and determine a threshold channel address in the particle pulse amplitude spectrum.

[0036] In some embodiments, the particle pulse amplitude spectrum may be a voltage signal generated by ionized particles generated by a nuclear reaction, as well as a voltage signal generated by noise signals in the detector's environment. This voltage signal may be an analog voltage signal and has not been discriminated by a discriminator. In some embodiments, after obtaining the particle pulse amplitude spectrum, a threshold value is determined from the particle pulse amplitude spectrum. This threshold value is used to distinguish between voltage signals corresponding to noise and voltage signals corresponding to particles generated by a nuclear reaction.

[0037] In some embodiments, the channel address value and the voltage amplitude have a one-to-one correspondence. After obtaining the voltage signal, the voltage amplitude in the voltage signal can be determined, and the voltage amplitude can be input into the multi-channel analyzer to obtain the channel address value corresponding to the voltage amplitude based on the correspondence between the channel address value and the voltage amplitude.

[0038] S102. Obtain at least one candidate channel address value greater than a threshold channel address from the particle pulse amplitude spectrum.

[0039] In some embodiments, the voltage amplitude corresponding to the candidate track address value is the magnitude of the voltage generated by the ionization of target particles, which are particles produced by nuclear reactions. For example, protons and tritium produced by the reaction of He-3 and neutrons are target particles; alpha particles produced by the decay of uranium isotopes are also target particles. In some embodiments, in nuclear radiation detectors, target particles produced by nuclear reactions will ionize and generate electrical signals. The voltage amplitude of these electrical signals, after processing by appropriate circuits, can be converted into corresponding track address values, i.e., candidate track address values.

[0040] S103: Determine a target count rate based on the particle pulse amplitude spectrum and at least one candidate channel address value.

[0041] In some embodiments, because the candidate track address values correspond to the amplitude of the voltage generated after the target particle is ionized, a target count rate can be determined based on the particle pulse amplitude spectrum and the candidate track address values. The target count rate represents the number of nuclear reactions that generate the target particle per unit time. In practical applications, the count value for each candidate track address value and the measurement time of the particle pulse amplitude spectrum (i.e., the first observation time) can be obtained from the particle pulse amplitude spectrum. The target count rate is determined as the ratio of the total count value corresponding to each candidate track address to the measurement time.

[0042] S104 , acquiring each logic signal, and determining a candidate count rate corresponding to each logic signal.

[0043] In some embodiments, each logic signal is obtained by discriminating a mixed analog voltage signal formed by target particle ionization and electronic noise when the discriminator is set to different reference discrimination thresholds. In practice, the reference discrimination threshold can be set by adjusting a knob on the discriminator. The mixed analog voltage signal includes the electrical signal formed by target particle ionization and the electrical signal formed by electronic noise. After obtaining the mixed analog voltage signal formed by target particle ionization and electronic noise, the mixed analog voltage signal can be input into the discriminator to obtain the logic signal output when the discriminator is set to different reference discrimination thresholds.

[0044] In some embodiments, the logic signal can be any positive voltage signal, for example, the logic signal can be +5V. When each logic signal is obtained, the count value corresponding to each logic signal can also be obtained. Then, based on the count value corresponding to each logic signal and the measurement time of the pulse amplitude spectrum of each logic signal (i.e., the second observation time), the candidate count rate corresponding to each logic signal can be determined.

[0045] S105 : Determine a reference discrimination threshold corresponding to the candidate counting rate that is the same as the target counting rate as the target discrimination threshold.

[0046] In some embodiments, the multiple candidate counting rates obtained include counting rates caused by target particles and may also include counting rates caused by electronic noise, while the target counting rate is only the counting rate caused by target particles. Therefore, the reference discrimination threshold corresponding to the candidate counting rate whose counting rate is the same as the target particle counting rate is determined as the target discrimination threshold.

[0047] In an embodiment of the present application, a particle pulse amplitude spectrum is first acquired and a threshold channel address in the particle pulse amplitude spectrum is determined. Then, at least one candidate channel address value greater than the threshold channel address is acquired from the particle pulse amplitude spectrum. The voltage amplitude corresponding to the candidate channel address value is the amplitude of the voltage generated after the ionization of the target particle, which is a particle produced after a nuclear reaction. Next, a target count rate is determined based on the particle pulse amplitude spectrum and the at least one candidate channel address value. Various logic signals are acquired and the candidate count rates corresponding to each logic signal are determined. Finally, a reference discrimination threshold corresponding to the candidate count rate identical to the target count rate is determined as the target discrimination threshold. In this manner, the target count rate is determined based on the particle pulse amplitude spectrum and the count values of the at least one candidate channel address value, and the reference discrimination threshold corresponding to the candidate count rate identical to the target count rate is determined as the target discrimination threshold. This allows the discriminator to remove the logic signals formed by the noise signal based on the target discrimination threshold, thereby ensuring the accuracy of the nuclear radiation detector in detecting nuclear events.

[0048] In some embodiments of the present application, determining the target count rate based on the particle pulse amplitude spectrum and at least one candidate channel address value, that is, step S103 can also be implemented by the following steps S1031 to S1033, and each step is described below.

[0049] S1031. Obtain a first count value corresponding to each candidate channel address value and a first observation time corresponding to the particle pulse amplitude spectrum.

[0050] It should be noted that in some embodiments, the candidate track address values and the voltage amplitudes generated after target particle ionization are in a one-to-one correspondence. Thus, the count value (i.e., the first count value) corresponding to each candidate track address value can be the number of times each voltage amplitude appears in the voltage signal generated after target particle ionization. In some embodiments, for example, if the voltage amplitudes in the voltage signal are 0.8V, 0.16V, 0.25V, and 0.46V, respectively, and the number of times each voltage amplitude appears is 650, 1700, 2500, and 4200, respectively, then the first count values of the candidate track addresses corresponding to each voltage amplitude are 650, 1700, 2500, and 4200, respectively.

[0051] In some embodiments, after obtaining the first count value corresponding to each candidate address value, the first observation time corresponding to the particle pulse amplitude spectrum can be obtained. The first observation time can be the measurement time of the particle pulse amplitude spectrum, which is the live time.

[0052] S1032: Sum the first count values corresponding to the candidate address values to obtain a total count value.

[0053] In some embodiments, after obtaining the first count values corresponding to each candidate address value, the first count values corresponding to each candidate address value can be summed to obtain a total count value. In practice, the total count value can represent the total number of voltage amplitudes in the voltage signal generated after the target particle nuclear reaction during the observation time.

[0054] S1033. Determine the ratio of the total count value to the first observation time as the target counting rate.

[0055] In some embodiments, after obtaining the first observation time corresponding to the total count value and the particle pulse amplitude spectrum, the ratio of the total count value to the first observation time can be determined as the target counting rate. In practice, the target counting rate can be expressed as the number of nuclear reactions that generate target particles per unit time.

[0056] In some embodiments of the present application, "determining the threshold address in the particle pulse amplitude spectrum" in step S101 can be implemented through the following steps S201 to S203, and each step is described below.

[0057] S201. When there are at least two consecutive reference track address values having count values less than a count threshold in the particle pulse amplitude spectrum, obtain a maximum reference track address value and a minimum reference track address value of the at least two reference track address values.

[0058] In some embodiments, the count threshold is pre-set and can be a positive integer close to 0. The reference track value can be a track value at which the count value is zero, or a track value close to zero. There are two or more reference track values, and each reference track value is continuously distributed in the particle pulse amplitude spectrum. After obtaining at least two consecutive reference track values, the maximum and minimum reference track values among the reference track values can be further determined.

[0059] S202: Acquire from the pulse amplitude spectrum at least one first track address value whose track address value is smaller than a minimum reference track address value, and at least one second track address value whose track address value is larger than a maximum reference track address value.

[0060] It should be noted that in the particle pulse amplitude spectrum, the first channel address value is a channel address value less than the minimum reference channel address value, and the second channel address value is a channel address value greater than the maximum reference channel address value. In some embodiments, the voltage amplitude corresponding to the first channel address value is less than the voltage amplitude corresponding to the second channel address value, and the first channel address value and the second channel address value may include one or more. In some embodiments, as Figure 5 In the particle pulse amplitude spectrum shown, each first track address value is located on the left side of at least two consecutive reference track address values, and each second track address value is located on the right side of at least two consecutive reference track address values.

[0061] S203: When there is a first track address value whose count value is greater than the count threshold, and there is a second track address value whose count value is greater than the count threshold, determine a threshold track address based on at least two reference track address values.

[0062] In some embodiments, in the particle pulse amplitude spectrum, if the count value of one or more first address values is greater than the count threshold, and the count value of one or more second address values is greater than the count threshold, the threshold address can be determined based on at least two consecutive reference address values.

[0063] In some embodiments, Figure 5 In the particle pulse amplitude spectrum shown, the first channel address values in the low channel address area correspond to electronic noise, and the second channel address values in the high channel address area come from the target particles. There is a relatively flat plateau area with low counts between them. The channel address value in the middle position of the plateau area can be used as the threshold channel address.

[0064] For example, in some embodiments, when the number of reference track values is odd, the median of the consecutive reference track values may be determined as the threshold track. For example, if the consecutive reference track values are 66, 67, 68, 69, 70, 71, and 72, the threshold track determined is 69. In other embodiments, when the number of reference track values is even, the median of the consecutive reference track values may be determined first, and then one of the two reference track values adjacent to the median may be determined as the threshold track. For example, if the consecutive reference track values are 66, 67, 68, and 69, the median of these four reference track values is 67.5. In this case, either 67 or 68 may be determined as the threshold track.

[0065] It can be understood that in the embodiment of the present application, by obtaining a first track address value whose track address value is less than the minimum reference track address value and a second track address value whose track address value is greater than the maximum reference track address value from the particle pulse amplitude spectrum, and determining that there is a first track address value whose count value is greater than the counting threshold and a second track address value whose count value is greater than the counting threshold, a threshold track address is determined based on at least two consecutive reference track address values, so as to distinguish the track address value corresponding to the target particle and the track address value corresponding to the electronic noise according to the threshold track address, thereby achieving subsequent filtering of the voltage signal formed by the electronic noise.

[0066] In some embodiments of the present application, “determining candidate count rates corresponding to each logic signal” in step S104 can be implemented through the following steps S301 to S303 , each of which is described below.

[0067] S301: Determine the pulse amplitude spectrum corresponding to each logic signal.

[0068] It should be noted that the pulse amplitude spectra of logic signals corresponding to different reference discrimination thresholds are different. In some embodiments, when the discrimination thresholds set for the discriminator are different, the count rate of the logic signal output by the discriminator also varies. Due to the different discrimination thresholds, the discriminator processes the mixed analog voltage signal input differently. For example, for the same mixed analog voltage signal input to the discriminator, the count value corresponding to a logic signal with a higher discrimination threshold is smaller than the count value corresponding to a logic signal with a lower discrimination threshold. As a result, the pulse amplitude spectra of logic signals corresponding to different reference discrimination thresholds are different. In practice, when the discrimination thresholds are different, the logic signals output by the discriminator can be the same, for example, they can all be +5V.

[0069] In some embodiments, after obtaining the logic signals corresponding to each discrimination threshold, the pulse amplitude spectrum corresponding to each logic signal can be obtained through a multi-channel analyzer and a data acquisition system. The vertical axis corresponding to the pulse amplitude spectrum can represent the count value of the channel address value, in units of pieces, and the horizontal axis can represent the corresponding channel address value.

[0070] S302 : Obtaining a count value of a track address value corresponding to the i-th logic signal and a second observation time of the pulse amplitude spectrum of the i-th logic signal from the pulse amplitude spectrum of the i-th logic signal.

[0071] In some embodiments, if the number of logic signals, i.e., the number of discrimination thresholds, is N (N is a positive integer greater than 1), the count value of the channel address value corresponding to the i-th logic signal can be obtained from the pulse amplitude spectrum of the i-th logic signal (i=1, 2, ..., N). It should be noted that the count value of the channel address value corresponding to the i-th logic signal can be the count value of the logic signal output corresponding to the i-th discrimination threshold. In practice, since voltage amplitudes greater than the i-th discrimination threshold in the mixed analog voltage signal are all assigned to the logic signal for output, the pulse amplitude spectrum corresponding to the i-th logic signal only contains the count value corresponding to the logic signal. In some embodiments, the second observation time can be the measurement time of the pulse amplitude spectrum of the i-th logic signal. In practice, this measurement time can be selected according to actual needs, for example, 60 seconds, 120 seconds, etc.

[0072] S303: Determine the ratio of the count value of the channel address value corresponding to the i-th logic signal to the second observation time as the candidate count rate of the logic signal corresponding to the i-th discrimination threshold.

[0073] In some embodiments, the i-th discrimination threshold corresponds to the i-th logic signal, that is, the discrimination threshold and the logic signal output by the discriminator are one-to-one corresponding. For example, when the discrimination threshold set by the discriminator is the first discrimination threshold, the corresponding output logic signal is the first logic signal.

[0074] In some embodiments, after obtaining the count value of the channel address value corresponding to the i-th logic signal and the second observation time of the pulse amplitude spectrum corresponding to the i-th logic signal, the ratio of the count value of the channel address value corresponding to the i-th logic signal to the second observation time can be determined as the candidate count rate of the logic signal corresponding to the i-th discrimination threshold. In practice, the candidate count rate of the logic signal corresponding to the i-th discrimination threshold can represent the number of nuclear reactions and electronic noises generated by target particles per unit time when the discrimination threshold of the discriminator is set to the i-th discrimination threshold.

[0075] For example, Table 1 below shows the candidate count rates corresponding to various logic signals at different discrimination thresholds. In Table 1, a knob scale of 0_6 represents a discrimination threshold of 0.06V, while a knob scale of 0_80 represents a discrimination threshold of 0.8V. As can be seen from Table 1, the measurement time corresponding to different discrimination thresholds is 60s. As the discrimination threshold increases, the corresponding count value and count rate decrease accordingly.

[0076] Screening threshold Measuring time / s Count value Count rate / s-1 0_6 60 2362221 39370.350 0_8 60 758433 12640.550 0_10 60 183414 3056.900 0_20 60 71204 1186.733 0_30 60 70752 1179.200 0_40 60 70707 1178.450 0_50 60 70542 1175.700 0_60 60 70351 1172.517 0_70 60 69857 1164.283 0_80 60 69592 1159.867

[0077] In some embodiments of the present application, the logic signal may be a voltage signal. Based on this, "determining the pulse amplitude spectrum corresponding to each logic signal" in step S301 may be implemented through the following steps S401 to S403. Each step is described below.

[0078] S401, determining the voltage value of the i-th logic signal; based on a preset correspondence between the voltage value and the channel address value, determining the channel address value corresponding to the i-th logic signal.

[0079] In some embodiments, the voltage value corresponding to the i-th logic signal may be +5V. Before determining the channel address value corresponding to the i-th logic signal, the voltage value corresponding to the i-th logic signal may be determined first, and then the channel address value corresponding to the i-th logic signal may be obtained based on the corresponding preset correspondence between the voltage value and the channel address value.

[0080] S402: Obtain the count value of the address value corresponding to the i-th logic signal.

[0081] In some embodiments, after determining the channel address value corresponding to the i-th logic signal, the count value of the channel address value corresponding to the i-th logic signal can be obtained. The count value of the logic signal can be expressed as the sum of the number of nuclear reactions that generate target particles and the number of electronic noises when the mixed analog voltage amplitude is greater than the discriminator threshold.

[0082] S403 : Determine a pulse amplitude spectrum corresponding to the i-th logic signal based on the track address value corresponding to the i-th logic signal and the count value of the track address value corresponding to the i-th logic signal.

[0083] In some embodiments, after obtaining the track address value corresponding to the i-th logic signal and the count value of the track address value corresponding to the i-th logic signal, a pulse amplitude spectrum corresponding to the i-th logic signal can be obtained based on the track address value corresponding to the i-th logic signal and the count value of the track address value corresponding to the i-th logic signal. In the pulse amplitude spectrum corresponding to the i-th logic signal, the abscissa represents the track address value corresponding to the i-th logic signal, and the ordinate represents the count value of the track address value corresponding to the i-th logic signal.

[0084] In some embodiments of the present application, “obtaining each logic signal” can also be implemented through the following steps S501 to S502 , and each step is described below.

[0085] S501 : Acquire a mixed analog voltage signal formed by target particle ionization and electronic noise.

[0086] It should be noted that the mixed analog voltage signal is composed of the electrical signal generated by target particle ionization and the electrical signal generated by electronic noise. In some embodiments, target particles generated by nuclear reactions are ionized in a nuclear radiation detector. The ions and electrons generated by ionization move within the detector, inducing charge on the collector, thereby generating an electrical signal. Simultaneously, electronic components and the external operating environment can also generate interference signals in the electronic circuit, namely electronic noise. The electrical signal generated by the ionization of the target particles, after being processed by the preamplifier and main amplifier, and the electronic noise together form the mixed analog voltage signal.

[0087] S502 : sequentially inputting the mixed analog voltage signal into discriminators set to different reference discrimination thresholds to obtain various logic signals.

[0088] In some embodiments, after obtaining the mixed analog voltage signal, the mixed analog voltage signal can be input into a discriminator to obtain logic signals output by the discriminator when the discriminator corresponds to different reference discrimination thresholds. In some embodiments, the logic signals corresponding to different discrimination thresholds may be the same, but the count values corresponding to the logic signals may be different.

[0089] In some embodiments of the present application, "obtaining a mixed analog voltage signal formed by target particle ionization and electronic noise" in step S501 can be implemented through the following steps S5011 to S5013, and each step is described below.

[0090] S5011. Use nuclear matter to carry out nuclear reactions in the detector to produce target particles.

[0091] In some embodiments, the detector may be a He-3 detector, and the corresponding nuclear material is He-3 and neutrons. The nuclear reaction between He-3 and neutrons produces protons and tritium, and thus the corresponding target particles may be protons and tritium. In other embodiments, the detector may be a U-235 fission ionization chamber, and the corresponding nuclear material is a uranium isotope. The decay of the uranium isotope produces alpha particles, and thus the corresponding target particles may be alpha particles. Of course, the description herein of the detector, nuclear material, and the nuclear reaction between the nuclear material to produce the target particles is merely illustrative and is not intended to be limiting in this application.

[0092] S5012. Obtain the initial electrical signal generated by the ionization of the target particles.

[0093] In some embodiments, after the target particles are ionized, they induce charges on the collecting electrode of the nuclear radiation detector, thereby generating an electrical signal, i.e., an initial electrical signal. In practice, an external circuit connected to the nuclear radiation detector can be set outside the nuclear radiation detector, and the initial electrical signal can be processed through the external circuit.

[0094] S5013: Input the initial electrical signal into the preamplifier and the main amplifier in sequence for amplification to obtain a first reference electrical signal.

[0095] In some embodiments, the preamplifier can pre-amplify the initial electrical signal, which can also improve the signal-to-noise ratio and reduce the electrical signal corresponding to electronic noise in the initial electrical signal. The main amplifier can further amplify the electrical signal output from the preamplifier to obtain a shaped electrical signal, which facilitates subsequent processing of the electrical signal output from the main amplifier. In some embodiments, the electrical signal output from the main amplifier is an analog voltage signal corresponding to the target particle, i.e., a first reference electrical signal.

[0096] S5014: Acquire a second reference electrical signal formed by electronic noise, and determine the first reference electrical signal and the second reference electrical signal as a mixed analog voltage signal.

[0097] In some embodiments, electronic noise may exist in the detector environment, and may also be generated by any electronic device, such as a preamplifier, a main amplifier, etc. Therefore, the mixed analog voltage signal used to input the discriminator includes the electrical signal formed by the electronic noise. After determining the first reference electrical signal formed by the target particle, it is necessary to obtain the electrical signal formed by the electronic noise, that is, the second reference electrical signal, and finally determine the first reference electrical signal and the second reference electrical signal as a mixed analog voltage signal.

[0098] In an embodiment of the present application, a particle pulse amplitude spectrum is first acquired and a threshold channel address in the particle pulse amplitude spectrum is determined. Then, at least one candidate channel address value greater than the threshold channel address is acquired from the particle pulse amplitude spectrum. The voltage amplitude corresponding to the candidate channel address value is the amplitude of the voltage generated after the ionization of the target particle, which is a particle produced after a nuclear reaction. Next, a target count rate is determined based on the particle pulse amplitude spectrum and the at least one candidate channel address value. Various logic signals are acquired and the candidate count rates corresponding to each logic signal are determined. Finally, a reference discrimination threshold corresponding to the candidate count rate identical to the target count rate is determined as the target discrimination threshold. In this manner, the target count rate is determined based on the particle pulse amplitude spectrum and the count values of the at least one candidate channel address value, and the reference discrimination threshold corresponding to the candidate count rate identical to the target count rate is determined as the target discrimination threshold. This allows the discriminator to remove the logic signals formed by the noise signal based on the target discrimination threshold, thereby ensuring the accuracy of the nuclear radiation detector in detecting nuclear events.

[0099] The following describes the implementation process of the embodiment of the present application in actual application scenarios.

[0100] In some embodiments, Figure 6A flow chart of a method for accurately determining a discrimination threshold provided in an embodiment of the present application. The method for accurately determining a discrimination threshold provided in an embodiment of the present application can be performed as follows: Figure 6 Steps S601 to S604 are implemented as shown below. Figure 6 Describe each step.

[0101] S601. Obtain a particle pulse amplitude spectrum corresponding to particles generated after a nuclear reaction.

[0102] The particles produced after the nuclear reaction correspond to the target particles in other embodiments. In the embodiment of the present application, a U-235 fission ionization chamber is used for exemplary illustration. First, the U-235 fission ionization chamber is used to measure the alpha particles emitted by the uranium target in the ionization chamber. That is, the particles produced after the nuclear reaction are alpha particles. The corresponding electronic block diagram of the measurement is as follows: Figure 7 As shown. Figure 7 As shown, the electronic block diagram includes a U-235 fission ionization chamber 201, a preamplifier 202, a main amplifier 203, a multi-channel analyzer 204, and a data acquisition system 205. In the U-235 fission ionization chamber 201, uranium isotopes decay to produce alpha particles. After ionization in the working gas of the ionization chamber, the alpha particles generate electrical signals. The electrical signals are amplified by the preamplifier 202 and the main amplifier 203, respectively. The amplified voltage signals are then input into the multi-channel analyzer 204 and the data acquisition system 205 to obtain the corresponding particle pulse amplitude spectrum.

[0103] In some embodiments, after acquiring each channel address value corresponding to the voltage signal and the count value corresponding to each channel address value, the data acquisition system 205 can generate the following information based on each channel address value and the count value corresponding to each channel address value: Figure 8 The particle pulse amplitude spectrum shown in the upper middle part, Figure 8 The particle pulse amplitude spectrum in the upper middle part includes the pulse amplitude spectrum corresponding to alpha particles and the pulse amplitude spectrum corresponding to electronic noise. The lower part is the pulse amplitude spectrum corresponding to alpha particles after thresholding.

[0104] S602: Determine a target channel address value in the particle pulse amplitude spectrum, and obtain a target counting rate based on the target channel address value.

[0105] In some embodiments, the target track address value corresponds to the threshold track address in other embodiments, and is used to determine the track address value corresponding to the voltage amplitude formed by the ionization of particles produced by nuclear reactions in the particle pulse amplitude spectrum, that is, the track address value corresponding to the voltage amplitude formed by the ionization of alpha particles generated by uranium isotope decay. When determining the target track address value in the particle pulse amplitude spectrum, if Figure 8As shown, the track address value can be located in an area where the count value presents a groove and the track address value count value is zero or close to zero, and the track address value corresponding to the middle position of the groove area can be determined as the target track address value, for example Figure 8 The target address value determined in is 69.

[0106] In some embodiments, when the target track address value is obtained, the pulse amplitude corresponding to the electronic noise can be offset by the target track address value, such as Figure 8 As shown in the lower middle part, after passing the target channel value threshold, the pulse amplitude spectrum corresponding to the alpha particle is obtained. Afterwards, the target counting rate can be determined based on the measurement time of the obtained pulse amplitude spectrum and the sum of the count values corresponding to each channel value in the pulse amplitude spectrum (the target counting rate is determined based on the particle pulse amplitude spectrum and at least one candidate channel value), where the target counting rate can represent the number of nuclear reactions that generate target particles per unit time. Figure 8 The total counts of each channel address are 703233, and the measurement time is 600s. The corresponding target count rate is 1172.055s. -1 .

[0107] S603 : Determine the pulse amplitude spectrum of the corresponding output logic signal when the discriminator is set to different discrimination thresholds.

[0108] In some embodiments, the pulse amplitude spectrum of the logic signal from the discriminator Ortec 551 can be determined by Figure 9 The electronic block diagram shown is shown. Figure 9 As shown in FIG. 3 , the electronic block diagram includes a U-235 fission ionization chamber 301, a preamplifier 302, a main amplifier 303, a discriminator 304, a multi-channel analyzer 305, and a data acquisition system 306. The processing from the U-235 fission ionization chamber 301 to the main amplifier 303 is similar to the Figure 7 The processing from the U-235 fission chamber 201 to the main amplifier 203 is the same as that shown in FIG, and will not be repeated here. Figure 7 The difference is that the mixed analog voltage signal output from the main amplifier 303 is input to the discriminator 304. Different discrimination thresholds are set for the discriminator. When the mixed analog voltage amplitude is greater than the discrimination threshold, a logic signal is output. The logic signal is then input to the multi-channel analyzer 305 and the data acquisition system 306. The pulse amplitude spectrum of the logic signal corresponding to each discrimination threshold can be obtained, such as Figure 10 As shown, the pulse amplitude spectrum corresponding to the discrimination threshold scale of 0_60, the corresponding count is 70351, the measurement time is 60S, and the counting rate is 1172.517s -1 In some embodiments, the count values and count rates corresponding to various discrimination thresholds are shown in Table 1.

[0109] In some embodiments, as Figure 11 As shown in the figure, it is a corresponding relationship diagram between count rate and discrimination threshold. The threshold setting knob of the discriminator Ortec551 corresponds to 10 large scales, each large scale corresponds to 100 small scales, and the corresponding voltage range is 0~10V. Figure 12 For the general Figure 11 The corresponding relationship between the counting rate and the discrimination threshold after local amplification. When the target counting rate is 1172.055s -1 hour, Figure 12 The count rate shown in is a graph showing the relationship between the count rate near the target count rate and the corresponding discrimination threshold.

[0110] S604 : Determine candidate count rates corresponding to respective discrimination thresholds based on the pulse amplitude spectra of the respective logic signals, and determine the discrimination threshold corresponding to the candidate count rate that is the same as the target count rate as the target discrimination threshold.

[0111] In some embodiments, after obtaining the pulse amplitude spectrum corresponding to each logic signal, the counting rate corresponding to each discrimination threshold, i.e., the candidate counting rate, can be determined from the pulse amplitude spectrum. The counting rates corresponding to each discrimination threshold are shown in Table 1. Then, the discrimination threshold corresponding to the candidate counting rate that is the same as the target counting rate can be determined as the target discrimination threshold. For example, from Table 1 and Figure 12 It can be seen that when the target counting rate is 1172.055s -1 When the target counting rate is 1172.055s -1 The closest discriminator, Ortec551, has a threshold of 0_60 (60mV).

[0112] It is understandable that in the embodiment of the present application, since the output from the discriminator is a logic signal, it is not possible to remove the threshold by the channel address method as when measuring the particle pulse amplitude spectrum. However, the count rate of the signal coming out of the discriminator corresponds one-to-one to the discrimination threshold. Therefore, the count rate of the signal can be determined by first measuring the particle pulse amplitude spectrum through the detector, and then the pulse amplitude spectrum of the logic signal coming out of the discriminator under different discrimination thresholds can be measured to obtain the corresponding count rate. The discrimination threshold can be adjusted according to the particle signal count rate so that the count rate gradually approaches the signal count rate determined when measuring the particle pulse amplitude spectrum. By first measuring the particle pulse amplitude spectrum to determine the signal count rate after removing the electronic noise, and then measuring the relationship between the count rate of the signal coming out of the discriminator and the discrimination threshold, the correct threshold of the discriminator can be determined.

[0113] The above is merely an embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for determining a discriminator threshold, characterized in that: include: Acquire a particle pulse amplitude spectrum, and determine a threshold channel address in the particle pulse amplitude spectrum; Obtaining at least one candidate track address value greater than the threshold track address from the particle pulse amplitude spectrum, wherein the voltage amplitude corresponding to the candidate track address value is the amplitude of the voltage generated after the target particle is ionized, and the target particle is a particle generated after a nuclear reaction; Obtaining a first count value corresponding to each candidate channel address value and a first observation time corresponding to the particle pulse amplitude spectrum; Summing up the first count values corresponding to the candidate address values to obtain a total count value; determining a ratio of the total count value to the first observation time as a target count rate, where the target count rate represents the number of nuclear reactions that generate the target particles per unit time; Acquiring each logic signal and determining a candidate count rate corresponding to each logic signal, wherein each logic signal is obtained by discriminating a mixed analog voltage signal formed by the target particle ionization and electronic noise when the discriminator is set to different reference discrimination thresholds; A reference discrimination threshold corresponding to the candidate count rate that is the same as the target count rate is determined as the target discrimination threshold.

2. The method according to claim 1, characterized in that Determining the threshold channel address in the particle pulse amplitude spectrum includes: When there are at least two consecutive reference track address values with count values less than a count threshold in the particle pulse amplitude spectrum, obtaining a maximum reference track address value and a minimum reference track address value of the at least two reference track address values; Acquire from the pulse amplitude spectrum at least one first track address value whose track address value is smaller than the minimum reference track address value, and at least one second track address value whose track address value is larger than the maximum reference track address value; When there is a first track address value having a count value greater than the count threshold and there is a second track address value having a count value greater than the count threshold, the threshold track address is determined based on the at least two reference track address values.

3. The method according to claim 1, characterized in that Determining the candidate count rates corresponding to the respective logic signals includes: determining a pulse amplitude spectrum corresponding to each of the logic signals, wherein the pulse amplitude spectrums of the logic signals corresponding to different reference discrimination thresholds are different; Obtaining, from the pulse amplitude spectrum of the i-th logic signal, a count value of the track address value corresponding to the i-th logic signal and a second observation time of the pulse amplitude spectrum of the i-th logic signal, where i=1, 2, ..., N, where N is a positive integer greater than zero; The ratio of the count value of the channel address value corresponding to the i-th logic signal to the second observation time is determined as the candidate count rate of the logic signal corresponding to the i-th discrimination threshold, wherein the i-th discrimination threshold corresponds to the i-th logic signal.

4. The method according to claim 3, characterized in that The logic signal is a voltage signal, and determining the pulse amplitude spectrum corresponding to each logic signal includes: Determine the voltage value of the i-th logic signal; determine the channel address value corresponding to the i-th logic signal based on a preset correspondence between the voltage value and the channel address value; Obtaining a count value of the channel address value corresponding to the i-th logic signal; Based on the track address value corresponding to the i-th logic signal and the count value of the track address value corresponding to the i-th logic signal, a pulse amplitude spectrum corresponding to the i-th logic signal is determined.

5. The method according to any one of claims 1 to 4, characterized in that The obtaining of each logic signal includes: Acquiring a mixed analog voltage signal formed by the target particle ionization and electronic noise; The mixed analog voltage signal is sequentially inputted into discriminators set to different reference discrimination thresholds to obtain various logic signals.

6. The method according to claim 5, characterized in that The step of obtaining a mixed analog voltage signal formed by the target particle ionization and electronic noise includes: Using nuclear matter to carry out nuclear reaction in the detector to produce the target particles; Acquiring an initial electrical signal generated by ionization of the target particles; Inputting the initial electrical signal into a preamplifier and a main amplifier in sequence for amplification processing to obtain a first reference electrical signal; A second reference electrical signal formed by the electronic noise is acquired, and the first reference electrical signal and the second reference electrical signal are determined as the mixed analog voltage signal.

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