Multi-path formed nuclear pulse processing method

Abstract

The invention discloses a multipath forming nuclear pulse processing method, which comprises the following steps of: performing filtering forming on an original pulse signal according to a trapezoidal forming method, dividing trapezoidal forming into n paths, sequentially increasing the rising time of the first path to the nth path, setting the flattop time of the first path as a minimum unit, and setting the flattop time of other paths as a fixed value L; taking the first path of filtering shaping waveform as a fast channel waveform, and taking the other paths of filtering shaping waveforms as to-be-selected shaping channel waveforms; when the rising edge of the fast channel waveform triggers an amplitude trigger threshold, taking the rising edge as a pulse and recording a trigger moment; calculating the time difference between each pulse and front and back pulses; and taking the time difference as a reference, and taking the to-be-selected forming channel waveform as a final forming channel waveform. According to the invention, a plurality of slow channels with different forming time are arranged, the channel with proper forming time is dynamically selected, and signals do not need to be discarded, so that more useful signals are obtained, and the accuracy of the signals is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of nuclear instrumentation technology, and in particular to a method for processing multi-channel shaped nuclear pulses. Background Technology

[0002] The signals output by detectors in nuclear instruments are generally random, exponentially decaying signals, with the signal amplitude corresponding to the energy of the radiation. In the signal analysis and processing of the back-end multichannel pulse amplitude analyzer, the main objective is to accurately extract the signal amplitude and perform filtering to improve the signal-to-noise ratio (SNR). Traditional analog multichannel analyzers use multi-stage low-pass filtering to shape the signal into a quasi-Gaussian signal, improving the SNR, and then determine the signal amplitude through peak hold and ADC (Analog-to-digital converter) sampling. In the latest digital multichannel technology, the detector output signal is directly digitized using a high-speed ADC, and then directly shaped into a quasi-Gaussian or trapezoidal shape through digital Gaussian shaping, digital trapezoidal shaping, and other digital operations before amplitude extraction. The following is the process of a trapezoidal shaping method: δ[n]=s[n]-as[n-] p[n]=δ[n]-δ[nJ]-δ[nJK]+δ[n-2J-K] q[n] = q[n-1] + p[n] z[n] = z[n-1] + q[n] Where s[n] is a discrete nuclear pulse signal, T is the digital sampling period, M is the decay time constant of the nuclear pulse signal, J is the number of hypotenuse points of the trapezoid (also known as the rise time), K is the number of flattened vertices of the trapezoid (also known as the flattened time), and L = 2J + K is the number of base points of the trapezoid. The forming process is as follows: Figure 1 As shown.

[0003] The detector output signal and the signal after digital laddering are as follows: Figure 2 As shown, the original pulse signal is an exponentially decaying pulse signal, and the two signals exhibit pulse stacking. However, after trapezoidal shaping, the pulse amplitude of the signal is consistent with the height of the trapezoid, the top of the trapezoid is flat, and no stacking occurs, making amplitude extraction easier.

[0004] Trapezoid formation is primarily controlled by two parameters: rise time (number of points on the hypotenuse) and top time (number of points at the top). Here, the number of points refers to the ADC sampling points, corresponding to the time interval. The top time is the width of the trapezoid's top; this value is generally small and fixed, so it usually doesn't need adjustment. According to filtering principles, increasing the trapezoid's rise time can enhance signal filtering and improve the signal-to-noise ratio. However, an excessively long rise time will result in an excessively large total trapezoid width, causing interference in the formed trapezoid, leading to signal accumulation, making it impossible to extract accurate amplitude, and resulting in signal loss and dead time. Figure 3 As shown, the trapezoidal rise time is based on 200 sampling points. Two trapezoids are already adjacent, but amplitude extraction can still be performed. For example... Figure 4 As shown, the trapezoidal rise time has 270 sampling points. The two trapezoids are severely clustered, making amplitude extraction impossible. At this point, the two pulses need to be discarded, and the time occupied by the two pulses becomes the dead time.

[0005] Because of the randomness of nuclear pulse signals, the generation of pulses is random. For a fixed rise time, when the pulse count rate is high, the probability of accumulation is greater and the dead time is longer. When the pulse count rate is low, the probability of accumulation is smaller and the dead time is shorter.

[0006] The current problem is that in real-time signal processing, the trapezoidal shaping can only select a certain rise time (generally, a larger rise time is chosen to ensure resolution). This inevitably leads to a large dead time at high count rates. While adjusting the rise time reduces the dead time, it also decreases the resolution. Moreover, because it is real-time signal processing, it is quite cumbersome to first measure for a period of time and then adjust the rise time based on the dead time. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a multi-channel shaping kernel pulse processing method. This method employs multi-channel parallel real-time shaping, with different rise times for different channels. When there is no pulse accumulation, data shaped using a long rise time is used; when pulses accumulate, data shaped using a shorter rise time is used. By using a dynamic selection method in real-time processing to select the shaping data for different channels based on the pulse conditions, dead time can be effectively reduced while improving resolution.

[0008] The embodiments of the present invention provide the following solutions: This invention provides a method for processing multi-channel shaping kernel pulses, the method comprising the following steps: Step 1: Filter and shape the original pulse signal using a trapezoidal shaping method. The trapezoidal shaping is divided into n paths, where the nth path is... i The ascent time of the road is ki The rise times of paths 1 through n increase sequentially; the flattening time of path 1 is set to the smallest unit, while the flattening times of other paths are set to fixed values. L ; Step 2: Use the first filtered and shaped waveform as the fast channel waveform, and the other filtered and shaped waveforms as the candidate shaped channel waveforms; Step 3: Set an amplitude trigger threshold in the fast channel waveform. Whenever the rising edge of the fast channel waveform triggers the amplitude trigger threshold, record it as a pulse and record the trigger time. Step 4: For each pulse in the fast-channel waveform, calculate the trigger time of that pulse. t 2. The trigger time of its preceding pulse t 1 First time difference Δ t 12 And calculate the trigger time of the pulse. t 2 and the triggering time of the subsequent pulse t 3 Second time difference Δ t 23 ; Step 5: For each pulse in the fast channel waveform, take the first time difference Δ t 12 Second time difference Δ t 23 The smaller value Δ t min As a comparison value, select k i + L Less than or equal to the smaller value Δ t min But it is closest to the smaller value Δ t min The candidate shaping channel waveform is used as the final shaping channel waveform of the pulse.

[0009] In an optional embodiment, the rise time in step one is... i The ascent time of the road is k i The value range is 1 to 1024.

[0010] In an optional embodiment, the flat-top time described in step one... L The value range is 1 to 512.

[0011] In one optional embodiment, the amplitude trigger threshold described in step three is in the range of 1 to 16384.

[0012] In an alternative embodiment, after step five, amplitude extraction is performed using the final shaped channel waveform.

[0013] The beneficial effects of this invention based on its technical solution are as follows: The present invention provides a multi-channel shaping kernel pulse processing method, which sets multiple slow channels as candidate shaping channels in addition to one fast channel waveform. Each slow channel has a different shaping time, and the channel with a suitable shaping time can be dynamically selected without discarding signals, so as to ensure the shaping filtering effect as much as possible, thereby obtaining more useful signals and significantly improving the signal accuracy. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the trapezoidal formation process.

[0016] Figure 2 This is a schematic diagram of the detector output signal and the signal after digital laddering.

[0017] Figure 3 This is a schematic diagram of the detector signal and the shaped signal with a rise time of 200 sampling points.

[0018] Figure 4 This is a schematic diagram of the detector signal and the shaped signal with a rise time of 270 sampling points.

[0019] Figure 5 This is a schematic diagram of the original pulse signal.

[0020] Figure 6 This is a schematic diagram of the first filtered waveform.

[0021] Figure 7 This is a schematic diagram of the second-path filtered waveform.

[0022] Figure 8 This is a schematic diagram of the waveform shaped by the third-channel filter.

[0023] Figure 9 This is a schematic diagram of the fourth-channel filtered waveform.

[0024] Figure 10 This is a schematic diagram showing the rising edge trigger time.

[0025] Figure 11 This is a schematic diagram of amplitude extraction for the first and second pulses.

[0026] Figure 12 This is a schematic diagram of the amplitude extraction for the third pulse. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the protection scope of the embodiments of the present invention.

[0028] A method for processing multi-channel shaping kernel pulses, the method comprising the following steps: Step 1: Figure 5 The original pulse signal shown is filtered and shaped using a trapezoidal shaping method. In this embodiment, the trapezoidal shaping is divided into four parallel processing paths, each with a different rise time. The rise time can be set according to the processing chip's capacity and the front-end ADC sampling rate, typically from 1 to 1024, with extreme values ​​potentially ranging from 1 to 65536. Higher values ​​require higher processing capacity. In this embodiment, the rise times are 5, 10, 100, 250, and 400. The flattening time typically ranges from 1 to 512, with extreme values ​​potentially ranging from 1 to 16384. In this embodiment, the flattening time of the first path is set to 1, while the flattening times of the other paths are set to fixed values. L =20.

[0029] The first ladder-forming waveform is as follows: Figure 6 As shown, Figure 6 As shown, the rise time is 5 seconds and the flattening time is 1 second. The second ladder formation signal is as follows: Figure 7 As shown, the rise time is 100, and the flattening time is 20; the third-path trapezoidal forming signal is as follows. Figure 8 As shown, the rise time is 250, and the flattening time is 20; the fourth trapezoidal forming signal is as follows. Figure 9 As shown, the rise time is 400 and the flat-top time is 20.

[0030] Step 2: Use the first filtered and shaped waveform as the fast channel waveform, and the other filtered and shaped waveforms as candidate shaped channel waveforms. The fast channel is used to distinguish pulses, so it needs a small rise time and a minimum flat-top time to achieve optimal pulse resolution.

[0031] Step 3: Set the amplitude trigger threshold in the fast channel waveform, ranging from 1 to 16384, with an extreme case of 1 to 65536. In this embodiment, the amplitude trigger threshold is set to 200. Each time the rising edge of the fast channel waveform triggers the amplitude trigger threshold, it is recorded as a pulse. Figure 10 As shown, the rising edge trigger times are respectively t 1 = 500 t 2=700, t 3 = 1400.

[0032] Step 4: For each pulse in the fast-channel waveform, calculate the trigger time of that pulse. t 2. The trigger time of its preceding pulse t 1 First time difference Δ t 12 And calculate the trigger time of the pulse. t 2 and the triggering time of the subsequent pulse t 3 Second time difference Δ t 23 .

[0033] For the first pulse, the trigger time is 500, the time difference between it and the trigger time of the previous pulse is greater than 420, and the time difference between it and the trigger time of the next pulse is 200. For the second pulse, the trigger time is 700, the trigger time difference between it and the previous pulse is 200, and the trigger time difference between it and the next pulse is greater than 420. For the third pulse, the trigger time is 1400, and the time difference between its trigger time and the trigger time of the previous pulse is greater than 420, and the time difference between its trigger time and the trigger time of the next pulse is also greater than 420.

[0034] Step 5: For each pulse in the fast channel waveform, take the first time difference Δ t 12 Second time difference Δ t 23 The smaller value Δ t min As a comparison value, select k i + L Less than or equal to the smaller value Δ t min But it is closest to the smaller value Δ t min The candidate shaping channel waveform is used as the final shaping channel waveform of the pulse.

[0035] For the first pulse, the minimum time difference is 200. Among the three paths, the one with a rise time of 100 and a flat-top time of 20 is the one with a rise time of 100 and a flat-top time of 20, which is the forming path. For the second pulse, the minimum time difference is 200. Among the three paths, the one that is less than or equal to but close to 200 is 120, that is, the path with a rise time of 100 and a flat-top time of 20 is the forming path. For the third pulse, its minimum time difference is greater than 420. Among the three paths, the one that is less than or equal to but close to 420 is 420, that is, the path with a rise time of 400 and a flat-top time of 20 is the forming path.

[0036] Finally, the final shaped channel waveform can be used for operations such as amplitude extraction. like Figure 11 As shown, for the first pulse, the selected rising time of the forming path is 100, and the flattening time is 20. The value taken at the middle position of the top of the first trapezoid of this forming path is the trapezoidal amplitude value of 8191; for the second pulse, the selected rising time of the forming path is 100, and the flattening time is 20. The value taken at the middle position of the top of the second trapezoid of this forming path is the trapezoidal amplitude value of 4093.

[0037] like Figure 12 As shown, for the third pulse, the selected rising time of the forming path is 400, and the flattening time is 20. The value taken at the middle position of the top of the third trapezoid of the forming path is the amplitude value of the trapezoid, 4091.

[0038] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0039] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (modules, systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0040] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0041] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0042] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0043] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for processing multi-channel shaping kernel pulses, characterized in that, The method includes the following steps: Step 1: Filter and shape the original pulse signal using a trapezoidal shaping method. The trapezoidal shaping is divided into n paths, where the nth path is... i The ascent time of the road is k i The rise times of paths 1 through n increase sequentially; the flattening time of path 1 is set to the smallest unit, while the flattening times of other paths are set to fixed values. L ; Step 2: Use the first filtered and shaped waveform as the fast channel waveform, and the other filtered and shaped waveforms as the candidate shaped channel waveforms; Step 3: Set an amplitude trigger threshold in the fast channel waveform. Whenever the rising edge of the fast channel waveform triggers the amplitude trigger threshold, record it as a pulse and record the trigger time. Step 4: For each pulse in the fast-channel waveform, calculate the trigger time of that pulse. t 2. The trigger time of its preceding pulse t 1 First time difference Δ t 12 And calculate the trigger time of the pulse. t 2 and the triggering time of the subsequent pulse t 3 Second time difference Δ t 23 ; Step 5: For each pulse in the fast channel waveform, take the first time difference Δ t 12 Second time difference Δ t 23 The smaller value Δ t min As a comparison value, select k i + L Less than or equal to the smaller value Δ t min But it is closest to the smaller value Δ t min The candidate shaping channel waveform is used as the final shaping channel waveform of the pulse.

2. The multi-channel shaping kernel pulse processing method according to claim 1, characterized in that: The rise time described in step one i The ascent time of the road is k i The value range is 1 to 1024.

3. The multi-channel shaping kernel pulse processing method according to claim 1, characterized in that: The flattening time mentioned in step one L The value range is 1 to 512.

4. The multi-channel shaping kernel pulse processing method according to claim 1, characterized in that: The range of the amplitude trigger threshold mentioned in step three is 1~16384.

5. The multi-channel shaping kernel pulse processing method according to claim 1, characterized in that: After step five, amplitude extraction is performed using the final shaped channel waveform.

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