Multi-condition joint constraint-based photoelectron coincidence event screening method and system

Abstract

The application discloses a kind of based on multi-condition joint constraint photoelectron coincidence event screening method and system, belong to photoelectron detection data processing technical field.The application includes: obtaining photoelectron event data that event type detector outputs;Event candidate group is generated based on time information;Time condition screening is applied to candidate event group;At least one of energy condition screening based on energy conservation law and momentum condition screening based on momentum conservation law is applied to event group screened by time condition, and the joint condition screening;Output candidate event group satisfying joint condition screening as photoelectron coincidence event.The application effectively suppresses accidental coincidence background by combining time condition with constraint based on physical conservation law, improves the physical credibility of coincidence event, and can be modularized configuration to adapt to different experimental needs, applicable to double photoelectron and multi-photoelectron correlation measurement.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic detection data processing technology, specifically to a method and system for screening optoelectronic coincidence events based on multi-condition joint constraints. Background Technology

[0002] In photoelectron spectroscopy experiments, important physical information related to electron correlation effects can be obtained by correlation analysis of multiple photoelectron events. Therefore, it is usually necessary to screen out coincidence events originating from the same physical process from a large number of detected photoelectron events.

[0003] In existing technologies, matching events are mostly based on a single condition, such as matching multiple events based on a time window. Specifically, by setting a time threshold, events occurring within that time threshold are judged as matching events. However, in actual measurements, photoelectron events not only exhibit randomness in time, but also statistical fluctuations in energy, momentum, and spatial distribution. Relying solely on a single time condition for matching can easily misclassify events that coincidentally occur in time but do not originate from the same physical process as matching events, introducing accidental matching and thus reducing the reliability of correlated measurement results.

[0004] Especially under event-driven detection conditions, the detector can record a large number of discrete photoelectron events in a short period of time. Under high event rates or multi-channel conditions, if coincidence screening is performed solely based on time conditions, a high proportion of non-physically related events may be included in the coincidence events, which can seriously interfere with subsequent physical analysis.

[0005] To mitigate the impact of random coincidences, some techniques attempt to introduce additional selection criteria, such as constraints based on energy or momentum conservation. However, existing methods typically suffer from the following shortcomings: First, they use each selection criterion independently, for example, performing time-based screening followed by energy-based screening, without forming a true "joint constraint" mechanism, resulting in limited screening effectiveness. Second, they lack a systematic screening process that effectively combines time conditions with energy and momentum conditions based on physical conservation laws, making it difficult to significantly improve the purity of coincidence events while ensuring screening efficiency. Third, existing methods are mostly tailored to specific application scenarios, employing empirical rules rather than strictly adhering to physical conservation laws, making them unsuitable for the high requirements of physical authenticity in photoelectron spectroscopy experiments. Summary of the Invention

[0006] This invention provides a method and system for screening photoelectron coincidence events based on multi-condition joint constraints, aiming to solve the following technical problems: how to effectively reduce the proportion of accidental coincidences in coincidence events under event-type detection conditions, improve the physical reliability of coincidence events, and construct a multi-condition joint coincidence screening method suitable for dual-photoelectron or multi-photoelectron measurements.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention discloses a method for screening photoelectron coincidence events based on multi-condition joint constraints, comprising the following steps: Step 1: Acquire photoelectron event data output by the event-type detector. The photoelectron event data includes at least time information and measurement information for characterizing energy and momentum. Step 2: Based on the time information, generate a candidate event group from the photoelectron event data, wherein the candidate event group includes at least two photoelectron events; Step 3: Apply time condition filtering to the candidate event group, specifically: calculate the time difference between any two photoelectron events in the candidate event group, and retain the candidate event group whose time difference meets the preset time consistency threshold condition; Step 4: Apply joint condition screening to the candidate event group that has passed the time condition screening, the joint condition screening including at least one of energy condition screening and momentum condition screening; The energy condition screening is based on the law of conservation of energy, which determines whether the sum of the energy of the candidate event group is within the preset reference total energy threshold range, and retains the candidate event group that meets the condition. The momentum condition screening is based on the law of conservation of momentum, which determines whether the sum of the momentum of the candidate event group is within the preset reference total momentum threshold range, and retains the candidate event group that meets the condition. Step 5: Output the candidate event groups that meet the joint condition screening as the final photoelectron coincidence events.

[0008] Preferably, the measurement information used to characterize energy and momentum is detector coordinate information, wherein the first dimension coordinates have a monotonic mapping relationship with momentum, and the second dimension coordinates have a monotonic mapping relationship with energy; The energy condition screening is implemented by converting the law of energy conservation into a constraint on the sum of the second-dimensional coordinates. The selection criteria are as follows:

[0009] If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where n≥2, y i Let y be the second-dimensional coordinate of the i-th event. ref The coordinate value corresponding to the preset total reference energy is Δy, and the preset energy tolerance threshold is Δy. The momentum condition screening is achieved by converting the law of conservation of momentum into a constraint on the sum of the coordinates of the first dimension. The selection criteria are as follows:

[0010] If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where n≥2, x i Let x be the first-dimensional coordinate of the i-th event. center Δx is the preset coordinate value of the center of symmetry, and Δx is the preset momentum tolerance threshold.

[0011] Preferably, the energy condition screening further includes an energy difference constraint to determine whether the energy difference of candidate event groups is within a preset energy difference threshold range. The selection criteria are as follows: For any two photoelectron events in the candidate event group that are sequentially adjacent, the energy difference constraint is:

[0012] If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where j and i are positive integers greater than 0, y offset ΔE is the preset energy differential center bias, and ΔE is the preset energy differential tolerance threshold.

[0013] Preferably, the momentum condition screening further includes momentum difference constraints to determine whether the momentum difference of candidate event groups is within a preset momentum difference threshold range. The selection criteria are as follows: For any two photoelectron events in the candidate event group that are sequentially adjacent, the momentum difference constraint is:

[0014] If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where j and i are positive integers greater than 0, x offset The preset momentum difference center bias is ΔA, which is the preset momentum difference tolerance threshold.

[0015] Preferably, the method for generating candidate event groups in step 2 is as follows: the photoelectron event data is sorted by timestamp, and a sliding time window method is used to pair up time-adjacent photoelectron events only within the time window to generate candidate event groups, thereby reducing the complexity of candidate generation from... Reduced to approximation , where N is the total number of events and m is the average number of events within the time window.

[0016] Preferably, the method further includes step 6: a purity evaluation step for matching events: based on the time difference distribution histogram of the output candidate event pairs, the purity of the true matching events is calculated by comparing the peak region count with the sideband background region count. The calculation formula is as follows:

[0017] in, To accurately reflect event purity, S represents the total count within the peak window, and B2 represents the equivalent background count converted to the peak window based on the count in the side background area.

[0018] Secondly, the present invention also discloses a photoelectronic coincidence event screening system based on multi-condition joint constraints, comprising: Event data acquisition module: used to acquire photoelectron event data output by event-type detectors. Each photoelectron event data includes at least time information and measurement information for characterizing energy and momentum. Candidate event pair generation module: used to generate a candidate event group from the photoelectron event data based on the time information, wherein the candidate event group includes at least two photoelectron events; Time condition filtering module: used to apply time condition filtering to the candidate event group, specifically: calculate the time difference between any two photoelectron events in the candidate event group, and retain the candidate event group whose time difference meets the preset time consistency threshold condition; Joint condition screening module: includes at least one of energy condition screening module and momentum condition screening module; Energy condition filtering module: used to apply energy condition filtering based on the law of conservation of energy to the candidate event group that has passed the time condition filtering, to determine whether the sum of the energy of the candidate event group is within the preset reference total energy threshold range, and to retain the candidate event group that meets the conditions; Momentum condition filtering module: used to apply momentum condition filtering based on the law of conservation of momentum to the candidate event group that has passed the time condition filtering, to determine whether the sum of the momentum of the candidate event group is within the preset reference total momentum threshold range, and to retain the candidate event group that meets the condition. The coincidence event output module is used to output the candidate event group that simultaneously meets the time condition and the joint condition, as the final photoelectron coincidence event.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: By employing a combined screening approach of "time conditions + conservation law constraints," the random coincidence background is significantly suppressed. Existing technologies often rely on single-time-window matching, resulting in a high proportion of random coincidences under high event rates. This invention, building upon time-condition screening, further introduces a combined condition screening based on the laws of energy conservation and / or momentum conservation, and outputs candidate event groups that simultaneously satisfy both time and combined conditions. Through the intersection constraints of multiple physical conditions, random combinations that coincide in time but do not conform to conservation laws are eliminated from a mechanistic perspective, significantly reducing the random coincidence background and highlighting the truly coincidental event component.

[0020] This invention employs a screening mechanism based on physical conservation laws to improve the physical reliability of matching events. Existing technologies often introduce additional selection conditions based on empirical rules, lacking physical basis. The energy and momentum condition screening methods used in this invention strictly adhere to the laws of energy and momentum conservation, respectively, giving the screening results clear physical significance. The screened event groups exhibit a clustering structure in the energy-momentum distribution consistent with conservation relationships, effectively eliminating random combinations inconsistent with actual physical processes from a physical mechanism perspective, thus greatly improving the authenticity of matching events and the reliability of the analysis results.

[0021] The screening process is modularly configured to adapt to different experimental needs. The combined conditional screening of this invention includes at least one of energy conditional screening and momentum conditional screening, which can be flexibly selected according to experimental conditions: energy conditional screening can be used alone in scenarios with high energy resolution, momentum conditional screening can be used alone in scenarios with high momentum resolution, and both screenings can be used simultaneously in scenarios where both are optimal. This modular configuration allows the invention to adapt to different types of detectors and diverse experimental needs, exhibiting broad applicability.

[0022] This invention is applicable to screening for two-electron and multi-electron coincidence events and is scalable. It not only provides a method for screening two-photoelectron coincidence events but also a method for screening multi-photoelectron coincidence events with three or more photoelectron events. By simultaneously applying time consistency and energy / momentum conservation constraints to multiple events, it achieves reliable extraction of multi-photoelectron correlation events, supporting higher-order correlation spectrum measurements and multi-electron dynamics research.

[0023] This invention provides a quantifiable purity evaluation method to facilitate the assessment of screening effectiveness. It also provides a method for calculating the purity of true coincidence events based on sideband background estimation. By comparing peak counts with sideband background counts, the purity of coincidence events under different screening conditions can be quantitatively evaluated, providing an objective basis for optimizing experimental parameters and verifying screening effectiveness.

[0024] This invention is suitable for event-based detection and high-event-rate scenarios, significantly reducing computational costs. Preferably, events are sorted by timestamp and candidate event pairs are generated using a sliding time window method, forming candidate event pairs only within a local neighborhood, thus reducing the candidate generation complexity from O(N^2) to O(N^2). 2 Reduced to approximate This significantly improves processing efficiency and scalability while ensuring the screening effect. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the candidate event pair generation strategy under high event rate conditions, where (a) is a pairwise combination of fully connected components, and (b) is the neighborhood pairing within the time window of the present invention. Figure 2 This is a schematic diagram of the screening process for dual photoelectron event pairs under the combined conditions of the present invention; Figure 3 This is a geometric selection diagram of the momentum conservation and energy conservation constraints of the present invention on the detector coordinates. (a) shows the central symmetry and differential selection in the x-direction corresponding to momentum conservation, and (b) shows the total energy in the y-direction and differential selection corresponding to energy conservation. Figure 4 This is a schematic diagram illustrating the calculation of the purity of true coincidence events based on the sideband background estimation of the present invention; Figure 5 A comparison chart of the Δt distribution of event pairs obtained under different association screening conditions under unified measurement conditions; Figure 6 A graph comparing the retention rate of event pairs with the purity of true matching events under different joint screening conditions; Figure 7 This is a schematic diagram of the energy and momentum distribution of event pairs after applying joint screening conditions. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1 This embodiment provides a dual-photoelectronic coincidence event screening method based on multi-condition joint constraints, such as... Figure 2 As shown.

[0028] Step 1: Event Data Acquisition. Photoelectron event data is acquired using an event-based detector. Each event record includes a timestamp t and the detector's two-dimensional coordinates (x, y). The x-coordinate has a monotonically varying relationship with the electron's momentum, and the y-coordinate has a monotonically varying relationship with the electron's energy. The detector records the arrival time and location information of each photoelectron.

[0029] Step 2: Generate candidate event pairs. For example... Figure 1 As shown in (a), to avoid computational explosion caused by fully connected combination, all events are sorted by timestamp. A coarse time window τ is set (e.g., corresponding to the typical time difference range of a physical process), and for each event, only m subsequent events with a time difference less than τ are paired as candidate event pairs. Figure 1 As shown in (a), this sliding time window method reduces the candidate generation complexity from Reduced to approximation , where N is the total number of events and m is the average number of events within the time window.

[0030] Step 3: Filter by time criteria. For example... Figure 1 As shown in (b), for the generated candidate event pairs, the time difference Δt = |t1 is calculated. t2 |. Retain values ​​where Δt is less than the preset fine-grained time window threshold t. real The event pairs are selected as candidate event pairs based on time conditions. This fine time window can be set according to the detector's system time resolution, for example, 2-3 times the detector's time resolution.

[0031] Step 4: Joint Condition Screening. In this embodiment, joint condition screening includes both energy condition screening and momentum condition screening.

[0032] 4.1 Momentum condition screening: such as Figure 3 As shown in (a), for the event pairs (x1, x2, y1, y2) that pass the time-filtering, a centrosymmetric constraint is first applied. For a two-electron emission process triggered by the same photon, the initial total momentum of the electron pair is approximately zero, which is expressed in the detector coordinates as about the center point x. center The distribution is centrally symmetric. The selection criteria for momentum condition screening are:

[0033] Where, x center Let Δx be the center of symmetry of the detector in the x-direction, and let Δx be a preset momentum tolerance threshold, which can be set according to the spatial resolution of the detector. This condition can effectively eliminate random pairing events that do not satisfy the symmetry relationship, thereby reducing the mismatch rate and accidental matching background.

[0034] Based on the aforementioned x-centrosymmetric selection method, this embodiment preferably introduces a relative difference constraint on the event pair in the x-direction to characterize the relative momentum relationship between the two electrons in the plane. The momentum difference (or relative emission angle difference) of the electron pair can be equivalently mapped to the detector x-coordinate difference. The distribution characteristics. Due to the possibility of increasing the bias setting, the "differential center" may not be strictly zero, but rather revolve around a certain bias amount. Clustering. For any candidate event pair (x1, x2), the following difference selection criteria are applied:

[0035] Where, x offset The x-differentiation center bias is pre-calibrated, and ΔA is a preset momentum difference tolerance threshold used to limit the allowable difference window width (corresponding to...). Figure 3 (The light red band in (a)). This condition can further eliminate random combinations that "accidentally fall into the centrally symmetric window but whose relative difference does not conform to the physical process characteristics", thereby further reducing the mismatch rate and the background of accidental matching.

[0036] 4.2 Energy condition screening: such as Figure 3As shown in (b), a total energy constraint is applied to event pairs that pass the momentum screening. For two electrons produced by the same triggering process, their energies must satisfy the energy conservation relation:

[0037] in Let be the reference total energy determined by the incident photon energy, sample work function, etc. The detector y-coordinate is monotonically mapped to the electron energy, allowing the energy conservation condition to be equivalently transformed into the detector coordinate condition.

[0038] Among them, y ref For reference total energy E ref The position corresponding to the detector in the y-direction can be determined by the incident photon energy, sample work function, etc.; Δy is a preset energy tolerance threshold, which can be set according to the detector's energy resolution.

[0039] Based on the above total y-energy selection, a further constraint on the energy difference (energy distribution) of event pairs in the y-direction is introduced. For two electrons generated by the same triggering process, in addition to satisfying the total energy conservation, their energy distribution usually also follows a expected symmetry or energy difference range (e.g., tending to bisect or satisfying a preset energy difference window). Since the detector y-coordinate is monotonically mapped to the electron energy, the above energy difference constraint can be equivalently converted into detector coordinate difference. Window selection.

[0040] Therefore, for any candidate event pair (y1, y2), the following difference selection condition can be further adopted:

[0041] Among them, y offset The preset energy differential center offset is used, and ΔE is the preset energy differential tolerance threshold, which limits the allowable differential window width (corresponding to...). Figure 3 (The dark blue band in (b)). This differential selection effectively suppresses random combinations of two events with unrelated energy distributions, further improving the purity and physical reliability of the output event pairs.

[0042] Step 5: Output the coincidence event. Output the candidate event pairs that simultaneously satisfy the time condition screening and the joint condition screening (i.e., simultaneously satisfy the momentum condition screening and the energy condition screening), as the final two-photoelectron coincidence events, for subsequent physical analysis.

[0043] Effect verification: such as Figure 5As shown, the red curve represents the Δt distribution obtained by using only the time window, the blue curve represents the Δt distribution after adding momentum constraints on the basis of the time window, and the green curve represents the Δt distribution after applying time window, momentum constraints and energy constraints simultaneously.

[0044] In one dataset, even with only time window filtering (red curve), a high level of flat noise is still present, indicating the presence of many coincidental events. After introducing momentum constraints (blue curve),... The noise level of the distribution is significantly reduced; after further combining energy and constraints (green curve), the noise level is further reduced and the curve tends to a lower stable plateau. These results demonstrate that multi-condition joint screening can effectively suppress accidental matching backgrounds and improve the purity and physical reliability of output event pairs without relying on additional hardware.

[0045] The above results indicate that multi-condition joint screening can effectively suppress accidental matching backgrounds.

[0046] like Figure 6 As shown, the bar chart represents the number of event pairs retained after processing with different screening conditions (corresponding to the left y-axis), and the line chart represents the purity of true matching events estimated from the side background (corresponding to the right y-axis). The three sets of conditions are: time-only screening, time + momentum screening, and time + momentum + energy screening.

[0047] In the same set of data, when only time window filtering is used, the number of retained event pairs is high but the purity is low, indicating that the proportion of accidental matching background is still significant. After further introducing momentum constraints, the number of retained event pairs decreases while the purity increases, indicating that momentum constraints can effectively exclude random pairing events that are inconsistent with momentum conservation. After further adding energy constraints, the number of retained event pairs continues to decrease while the purity continues to increase, indicating that multi-condition joint filtering can significantly suppress accidental matching background by constraining the intersection of time synchronization, momentum conservation, and energy conservation, thereby highlighting the real matching event components and improving the physical credibility of the output event pairs.

[0048] like Figure 7 As shown, the red scatter points represent the event pairs that are retained after simultaneously satisfying the time window selection, momentum conservation constraints, and energy conservation constraints. Figure 7 The momentum space shown in (a) is related to the momentum space in the middle. Figure 7 The joint distribution in the energy space shown in (b) exhibits an associated structure clustered along the constraint relations; the blue scatter points represent the event pairs retained after further superimposing differential constraints, which are in Figure 7 The momentum space shown in (c) is related to the momentum space in the middle. Figure 7The joint distribution in energy space (d) exhibits a denser clustering structure. This result indicates that after applying multi-condition joint screening to candidate event pairs, the output event pairs exhibit a clustered correlation structure in energy and momentum space along specific constraint relationships: on the one hand, the scattered points mainly fall in the region satisfying the total momentum constraint (corresponding to momentum conservation / detector centrosymmetry); on the other hand, the scattered points are simultaneously restricted to the vicinity of satisfying the total energy constraint and its allowable band (corresponding to energy conservation). This result shows that joint screening can significantly suppress the diffuse background of random coincidences in energy and momentum space and enhance the proportion of event pairs consistent with conservation relationships, thereby improving the purity and physical reliability of the output coincidence event pairs.

[0049] Purity evaluation: such as Figure 4 As shown, the blue shaded area represents the peak region ( The number of matching events obtained from the statistics within the period) Orange area This represents the background count obtained within the sideband window far from the peak region; The equivalent background is obtained by converting the window width to the peak area. It is used to estimate the contribution of accidental coincidence within the peak region.

[0050] Based on the histogram H(Δt) of the time difference distribution of the output event pairs, a peak region window is set. (e.g., near Δt≈0) and side background window (e.g., the areas on either side of the peak region). Count the total number of peak regions (blue area in the diagram). +Yellow area S Total count of adjacent background areas ( Figure 4 Background B1 .

[0051] Because the window widths of the peak area and the background area are different, The equivalent background is obtained by normalizing the window width and converting it to the peak area. Figure 4 Medium-efficiency background ) Then the estimated true coincidence count within the peak region ( Figure 4 (Middle blue area R) The true consistency of the event purity (the proportion of the peak area that truly matches). ,in , The larger the value, the fewer the random occurrences and the higher the purity of the output event pair. This purity evaluation method provides a quantifiable basis for assessing the screening effect.

[0052] Example 2 This embodiment is basically the same as Embodiment 1, except that the joint conditional screening only includes energy conditional screening and not momentum conditional screening. For some experimental scenarios with high energy resolution but low momentum resolution, a combination of time conditional screening and energy conditional screening can be used to effectively reduce the proportion of random coincidences. In this case, only energy conditional screening is performed in step 4, and step 5 outputs candidate event pairs that simultaneously satisfy both time and energy conditions.

[0053] Example 3 This embodiment is basically the same as Embodiment 1, except that the joint conditional screening only includes momentum conditional screening and not energy conditional screening. For some experimental scenarios with high momentum resolution but low energy resolution, a combination of time conditional screening and momentum conditional screening can be used. In this case, only momentum conditional screening is performed in step 4, and step 5 outputs candidate event pairs that simultaneously satisfy both time and momentum conditions.

[0054] Example 4 This embodiment is basically the same as Embodiment 1, except that the order of energy condition screening and momentum condition screening can be interchanged. Depending on experimental requirements, momentum condition screening can be performed first to quickly eliminate candidate event pairs that do not conform to momentum conservation, followed by energy condition screening; alternatively, energy condition screening can be performed first, filtering out possible event pairs based on energy information, and then applying momentum constraints. Both orders can achieve the technical effects of this invention, demonstrating the flexibility of this method.

[0055] Example 5 This embodiment provides a multi-photoelectronic coincidence event screening method based on multi-condition joint constraints, applicable to the coincidence screening of three or more photoelectronic events. Let the number of photoelectronic events to be screened be n, where n≥3.

[0056] Step 1: Event data acquisition. Same as Example 1.

[0057] Step 2: Candidate Event Group Generation. Sort all events by timestamp. Set a coarse time window τ (e.g., corresponding to the typical time difference range of a physical process). For each event as the starting event, search backwards for events with a time difference less than τ. If the number of events found reaches n... If there is 1, then the starting event will be linked to these n. Each event forms a candidate event n-tuple. To avoid an explosion in the number of candidate event groups, a sliding time window approach can be used, combining only n events that are consecutive in time, or combining only the starting event with all events within the time window that satisfy the temporal sequence relationship. Specifically, for event i, if events i+1, i+2, ..., i+n 1 satisfies |t i+k t i|<τ(k=1,2,…,n 1), then (i,i+1,…,i+n 1) Form a candidate event n-tuple.

[0058] Step 3: Time-based filtering. For the generated candidate event n-tuples, calculate the time difference between any two events. If the time difference of all event pairs is less than the preset fine-grained time window threshold t... real If the condition is met, then the n-tuple is retained. That is, it must satisfy:

[0059] Step 4: Joint Condition Screening. In this embodiment, joint condition screening includes both energy condition screening and momentum condition screening.

[0060] 4.1 Total Energy Condition Screening: For an n-electron process, the total energy conservation requirement dictates that the sum of the energies of all electrons equals the incident photon energy minus constants such as the work function. Utilizing the linear superposition property of the detector's y-coordinates (monotonically mapped to energy), the selection criterion for total energy condition screening is:

[0061] Where n≥3, and y i Let y be the second-dimensional coordinate (energy coordinate) of the i-th event. ref The coordinate value corresponding to the preset total reference energy is Δy, and the preset energy tolerance threshold is Δy. 4.2 Total Momentum Condition Screening: For an n-electron process, the conservation of total momentum requires that the sum of the momentum vectors of all electrons be zero (or a preset value). On the detector's x-coordinate (monotonically mapped to momentum), this is manifested as the average x-coordinate of all events being close to the detector center. The selection criteria for total momentum condition screening are:

[0062] Where n≥3, x i Let x be the first dimension coordinate (momentum coordinate) of the i-th event. center Δx is the preset coordinate value of the center of symmetry, and Δx is the preset momentum tolerance threshold.

[0063] Step 5: Output the candidate event n-tuples that simultaneously satisfy the time condition screening and the joint condition screening (i.e., simultaneously satisfy the total energy condition and the total momentum condition), as the final multi-photoelectron coincidence events.

[0064] Specific example (Sanguang Electronics): When n=3, the method for generating candidate event triples is as follows: For event i, if events j and k satisfy |t j t i |<τ and |tk t i If |<τ, then (i,j,k) constitutes a candidate triple. The time condition requires |t. j t i | <t real 、 |t k t i | <t real And |t k t j | <t real The total energy condition is |(y1+y2+y3) y ref | < Δy, the total momentum condition is |(x1+x2+x3) / 3 x center |<Δx. Output the triplet that satisfies all conditions.

[0065] Example 6 This embodiment is basically the same as embodiment 5, except that the energy condition screening also includes an energy difference constraint, which is used to determine whether the energy difference of the candidate event group is within a preset energy difference threshold range. The selection condition is as follows: For any two photoelectron events in the candidate event group that are sequentially adjacent, the energy difference constraint is:

[0066] If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where j and i are positive integers greater than 0, y offset ΔE is the preset energy differential center bias, and ΔE is the preset energy differential tolerance threshold.

[0067] Momentum condition screening also includes momentum difference constraints, used to determine whether the momentum difference of candidate event groups is within a preset momentum difference threshold range. The selection criteria are as follows: For any two photoelectron events in the candidate event group that are sequentially adjacent, the momentum difference constraint is:

[0068] If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where j and i are positive integers greater than 0, x offset The preset momentum difference center bias is ΔA, which is the preset momentum difference tolerance threshold.

[0069] This embodiment demonstrates that the method of the present invention can be naturally extended to the conformity screening of three or more photoelectron events. Those skilled in the art should understand that for the case where n>3, it can be achieved simply by extending the above general formula, without any inventive effort.

[0070] Example 7 This embodiment is basically the same as Embodiment 1, except for the window size τ of the sliding time window in step 2 and the fine time window threshold t in step 3. real The parameters in step 4, such as the momentum tolerance threshold Δx, energy tolerance threshold Δy, and difference tolerance thresholds ΔA and ΔE, can be dynamically adjusted based on the statistical results during the event screening process. For example, a more lenient threshold can be used in the early stages of screening to retain more candidate events, while the threshold can be adaptively narrowed in the later stages of screening based on statistical distribution characteristics, thereby improving screening efficiency and purity.

[0071] Example 8 This embodiment provides a photoelectronic coincidence event screening system based on multi-condition joint constraints, used to implement the method described in Embodiment 1. The system includes: Event Data Acquisition Module: This module connects to the data output interface of the event detector and receives real-time data on each photoelectron event collected by the detector, including timestamps, detector two-dimensional coordinates (x, y), and other information. This module may include a data buffer unit for temporarily storing event data within a certain time window.

[0072] Candidate event pair generation module: This module reads event data from the event data acquisition module, sorts it by timestamp, and uses a sliding time window method to pair adjacent or nearest-neighbor events only within a preset time window to generate candidate event pairs. This module can be implemented through hardware logic (such as FPGA) or software algorithms, with a complexity of O(N·m).

[0073] Time-condition filtering module: This module receives candidate event pairs, calculates the time difference of each event pair, compares it with a preset fine time window threshold, and retains event pairs with a time difference less than the threshold.

[0074] Joint Condition Screening Module: This module includes an energy condition screening submodule and a momentum condition screening submodule, one or both of which can be enabled depending on the experimental configuration. The energy condition screening submodule, based on the law of conservation of energy, calculates the sum of energies of event pairs (via y-coordinate mapping) and compares it with a reference total energy threshold; the momentum condition screening submodule, based on the law of conservation of momentum, calculates the sum of momentum of event pairs (via x-coordinate mapping) and compares it with a reference total momentum threshold.

[0075] Matching Event Output Module: This module receives all event pairs that pass through the filtering module, marks them as matching events, and outputs them to the subsequent analysis system or storage device.

[0076] The above modules can be integrated into a single data processing unit, such as a field-programmable gate array (FPGA), a digital signal processor (DSP), or a software program running in a general-purpose computer. Hardware implementation can further improve processing speed and real-time performance.

[0077] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for screening photoelectronic coincidence events based on multi-condition joint constraints, characterized in that, Includes the following steps: Step 1: Acquire photoelectron event data output by the event-type detector, wherein each photoelectron event data includes at least time information and measurement information for characterizing energy and momentum; Step 2: Based on the time information, generate a candidate event group from the photoelectron event data, wherein the candidate event group includes at least two photoelectron events; Step 3: Apply time condition filtering to the candidate event group, specifically: calculate the time difference between any two photoelectron events in the candidate event group, and retain the candidate event group whose time difference meets the preset time consistency threshold condition; Step 4: Apply joint condition screening to the candidate event group that has passed the time condition screening, the joint condition screening including at least one of energy condition screening and momentum condition screening; The energy condition screening is based on the law of conservation of energy, which determines whether the sum of the energy of the candidate event group is within the preset reference total energy threshold range, and retains the candidate event group that meets the condition. The momentum condition screening is based on the law of conservation of momentum, which determines whether the sum of the momentum of the candidate event group is within the preset reference total momentum threshold range, and retains the candidate event group that meets the condition. Step 5: Output the candidate event groups that meet the joint condition screening as the final photoelectron coincidence events; The measurement information used to characterize energy and momentum is detector coordinate information, wherein the first dimension coordinate has a monotonically mapped relationship with momentum, and the second dimension coordinate has a monotonically mapped relationship with energy; The energy condition screening is implemented by converting the law of energy conservation into a constraint on the sum of the second-dimensional coordinates. The selection criteria are as follows: If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where n≥2, y i Let y be the second-dimensional coordinate of the i-th event. ref The coordinate value corresponding to the preset total reference energy is Δy, and the preset energy tolerance threshold is Δy. The momentum condition screening is achieved by converting the law of conservation of momentum into a constraint on the sum of the coordinates of the first dimension. The selection criteria are as follows: If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where n≥2, x i Let x be the first-dimensional coordinate of the i-th event. center The coordinates of the preset center of symmetry are given, and Δx is the preset momentum tolerance threshold. The energy condition screening also includes an energy difference constraint, used to determine whether the energy difference of candidate event groups is within a preset energy difference threshold range. The selection criteria are as follows: For any two photoelectron events in the candidate event group that are sequentially adjacent, the energy difference constraint is: If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where j and i are positive integers greater than 0, y offset The preset energy difference center bias is ΔE, which is the preset energy difference tolerance threshold. The momentum condition screening also includes momentum difference constraints, used to determine whether the momentum difference of candidate event groups is within a preset momentum difference threshold range. The selection criteria are as follows: For any two photoelectron events in the candidate event group that are sequentially adjacent, the momentum difference constraint is: If the selection criteria are met, retain the candidate event group that meets the criteria; otherwise, discard it. Where j and i are positive integers greater than 0, x offset The preset momentum difference center bias is ΔA, which is the preset momentum difference tolerance threshold.

2. The photoelectron coincidence event screening method according to claim 1, characterized in that, The method for generating candidate event groups in step 2 is as follows: The photoelectron event data is sorted by timestamp, and a sliding time window method is used to pair up time-adjacent photoelectron events only within the time window to generate candidate event groups, thus reducing the complexity of candidate generation from... Reduced to approximation , where N is the total number of events and m is the average number of events within the time window.

3. A screening system for implementing the photoelectron coincidence event screening method based on multi-condition joint constraints as described in any one of claims 1-2, characterized in that, include: Event data acquisition module: used to acquire photoelectron event data output by event-type detectors. Each photoelectron event data includes at least time information and measurement information for characterizing energy and momentum. Candidate event pair generation module: used to generate a candidate event group from the photoelectron event data based on the time information, wherein the candidate event group includes at least two photoelectron events; Time condition filtering module: used to apply time condition filtering to the candidate event group, specifically: calculate the time difference between any two photoelectron events in the candidate event group, and retain the candidate event group whose time difference meets the preset time consistency threshold condition; Joint condition screening module: includes at least one of energy condition screening module and momentum condition screening module; Energy condition filtering module: used to apply energy condition filtering based on the law of conservation of energy to the candidate event group that has passed the time condition filtering, to determine whether the sum of the energy of the candidate event group is within the preset reference total energy threshold range, and to retain the candidate event group that meets the conditions; Momentum condition filtering module: used to apply momentum condition filtering based on the law of conservation of momentum to the candidate event group that has passed the time condition filtering, to determine whether the sum of the momentum of the candidate event group is within the preset reference total momentum threshold range, and to retain the candidate event group that meets the condition. The coincidence event output module is used to output the candidate event group that simultaneously meets the time condition and the joint condition, as the final photoelectron coincidence event.

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