Event-based delay line detector based angularly resolved multi-electron coincidence measurement system and method

Abstract

The application relates to the technical field of angle-resolved photoelectron spectroscopy experimental instruments, and discloses an angle-resolved multi-electron coincidence measurement system and method based on an event-type delay line detector, which comprises an angle-resolved energy analyzer, an event-type delay line detector, an external trigger and synchronization module and a time digitization readout module. The detection surface of the event-type delay line detector is divided into at least two independent areas, which are used for receiving photoelectrons in parallel and independently outputting event signals; the external trigger and synchronization module is used for generating a unified trigger period to establish a global time reference; the time digitization readout module is used for receiving the event signals and generating time stamps; and the data acquisition and processing module is used for performing correlation selection based on the time stamps in the same trigger period. The application reduces the dead time through multi-area parallel readout, realizes unified time base calibration through time baseline calibration and delay compensation, can realize multi-electron coincidence measurement while maintaining the angle-resolving capability, and is suitable for pulsed or continuous light sources.

Description

Technical Field

[0001] This invention relates to the field of angle-resolved photoelectron spectroscopy experimental instruments, specifically to a detection system and method for multi-electron coincidence measurement. Background Technology

[0002] Angle-resolved photoemission spectroscopy (ARPES) is one of the most direct and powerful experimental techniques in contemporary condensed matter physics and materials science for studying the electronic band structure of materials. Its basic principle is based on the photoelectric effect; by measuring the kinetic energy of photoelectrons at different emission angles, the energy-momentum dispersion relationship of electrons in a material can be directly obtained.

[0003] In existing conventional ARPES measurements, detection systems mostly employ integration-based or single-channel event accumulation readout schemes. The core of these schemes lies in the temporal and spatial accumulation and statistical analysis of a large number of photoelectron events within a fixed acquisition window, thereby generating a two-dimensional image reflecting the band structure (such as energy vs. momentum distribution curves). However, when experimental studies extend from single-particle behavior to multi-particle correlation effects (such as dual photoelectron emission, Auger electron cascades, Coulomb decay, etc.), the aforementioned traditional detection methods reveal significant technical shortcomings. In multi-electron measurement scenarios, multiple photoelectrons may arrive at the detector simultaneously or sequentially within a short coherence window of the same excitation pulse or the same continuous light source. For integration-based detection systems, multiple events may overlap spatially or temporally, leading to signal superposition, making it impossible to distinguish individual events and causing information loss. For traditional single-channel event readout systems, due to the existence of dead time, when multiple events flood in within a short period, event accumulation and readout conflicts are highly likely to occur, resulting in the loss of temporal information for subsequent events or inaccurate recording.

[0004] To study correlations between electrons, existing techniques have developed coincidence measurement methods. These methods typically rely on using multiple independent detectors to detect multiple emitted electrons, or employing pump-probe techniques combined with ultrafast time-delay scanning to construct temporal correlations. However, these existing schemes have insurmountable limitations: while using multiple discrete detectors can achieve temporal coincidence, they usually only cover a limited solid angle, completely losing the ability to perform energy-momentum mapping and failing to provide angular resolution information for the electrons. While pump-probe-based ultrafast time-scanning methods can achieve extremely high temporal resolution, the experimental systems are complex, the acquisition efficiency is low, and they are mainly applicable to tunable pulsed sources, making them difficult to apply to synchrotron radiation or conventional continuous light sources in laboratories.

[0005] Furthermore, in multi-channel event readout systems, inherent delay differences inevitably exist between different detection channels and their subsequent electronic links. If these differences are not corrected, electronic events originating from the same excitation process but detected in different regions will have timestamps in different time coordinate systems, leading to deviations or failures in subsequent time correlation selection.

[0006] In summary, current technologies lack a measurement scheme that can effectively handle concurrent readouts of multiple electron events while maintaining the energy and momentum resolution required for traditional ARPES experiments, and can uniformly calibrate the time differences between multiple channels, thereby reliably achieving time correlation discrimination between multiple electron events. How to achieve parallel, low dead-time readouts of multiple electron events, unified time-base calibration of multiple channels, and high-precision time correlation analysis on a detector plane with angular and energy resolution is a pressing technical challenge in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an angle-resolved multi-electron coincidence measurement system and method based on an event-type delay line detector. This addresses the problem that existing angle-resolved photoelectron spectroscopy systems struggle to achieve reliable multi-electron event coincidence measurement while maintaining energy and momentum resolution.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector, comprising:

[0010] An angle-resolved energy analyzer is used to receive photoelectrons emitted from a sample after it is irradiated by an excitation light source, and to perform spatial dispersion on the emission surface based on the energy and angle of the photoelectrons.

[0011] An event-type delay line detector is disposed on the output surface of the angle-resolved energy analyzer. Its detection surface is divided into at least two independent event detection regions for receiving photoelectrons dispersed by the angle-resolved energy analyzer in parallel and outputting corresponding event signals independently.

[0012] An external triggering and synchronization module is used to generate a unified triggering cycle signal and provide the triggering cycle signal to the excitation light source and the subsequent time digitization readout module to establish a global time reference.

[0013] The time digitization readout module is connected to each event detection area of ​​the event-type delay line detector, and is used to receive the event signal and generate a timestamp for each event signal containing the time when the event signal arrives at the event detection area based on the unified trigger period signal.

[0014] The data acquisition and processing module, connected to the time digitization readout module, is used to receive event signals with timestamps and perform correlation judgment based on the timestamps of event signals from different event detection areas within the same triggering period, identifying multiple event signals that meet preset time correlation conditions as conforming measurement events.

[0015] Preferably, the time digitization readout module includes a constant fraction timer and a time-to-digital converter; the event signal is processed by the constant fraction timer and then sent to the time-to-digital converter to generate the timestamp. This scheme can eliminate timing errors caused by signal amplitude fluctuations and improve the accuracy of the timestamp.

[0016] Preferably, the system supports an event time baseline calibration mode. In this mode, the external triggering and synchronization module synchronously triggers the excitation light source and the time digitization readout module, defining the emission time of the light pulse from the excitation light source as the start time of a measurement cycle, and collecting the arrival time distribution of event signals in each event detection area to obtain event time baseline information. This mode is used to obtain the inherent time characteristics of each detection channel.

[0017] Furthermore, the system compensates for the inherent time delay between the arrival times of event signals from different event detection areas based on the event time baseline information, ensuring that the timestamps from different event detection areas are in the same time coordinate system. This feature is key to achieving accurate conformity measurement in this invention; by correcting the inherent delay between channels, the accuracy of subsequent time correlation selection is fundamentally guaranteed.

[0018] Preferably, the system supports a multi-electron coincidence measurement mode; in the multi-electron coincidence measurement mode, the external triggering and synchronization module periodically activates the time digitization readout module to collect event signals from different event detection areas, and the data acquisition and processing module performs association and selection on multiple event signals based on the timestamp and according to the preset time association conditions within the same triggering cycle to identify coincidence measurement events.

[0019] Furthermore, the preset time association condition includes: combining the event signals within the same trigger period in pairs, calculating the time difference of each event signal pair, and determining the event signal pairs whose time difference is less than a preset compliance time window as compliance measurement events. This scheme provides specific compliance selection logic, which is simple and effective to implement.

[0020] Preferably, the detection area of ​​the event-type delay line detector is divided into two independent event detection areas, forming a dual-half-zone structure. This structure is easy to implement and matches the exit surface shape of common hemispherical analyzers.

[0021] Preferably, the angle-resolved energy analyzer is a hemispherical energy analyzer. The hemispherical analyzer is the most commonly used type of energy analyzer in ARPES experiments and has good compatibility.

[0022] Secondly, this invention provides an angle-resolved multi-electron coincidence measurement method based on an event-type delay line detector, applied to the aforementioned system, comprising the following steps:

[0023] Step S1: The photoelectrons emitted after the sample is irradiated by the excitation light source are energy and angle-resolved using an angle-resolved energy analyzer, and spatial dispersion is performed on the emission surface.

[0024] Step S2: At least two independent event detection regions of the event-type delay line detector set on the output surface of the angle-resolved energy analyzer are used to receive the dispersed photoelectrons in parallel and output the corresponding event signals independently.

[0025] Step S3: Generate a unified trigger cycle signal through the external triggering and synchronization module, and provide the trigger cycle signal to the excitation light source and the time digitization readout module respectively to establish a global time reference;

[0026] Step S4: Receive the event signal through the time digitization readout module, and generate a timestamp containing its arrival time for each event signal based on the unified trigger cycle signal;

[0027] Step S5: Receive event signals with the timestamps through the data acquisition and processing module, and perform correlation selection based on the timestamps of event signals from different event detection areas within the same triggering period, identifying multiple event signals that meet the preset time correlation conditions as qualified measurement events.

[0028] Furthermore, in step S5, events within the same triggering period are combined in pairs, the time difference of each event signal pair is calculated, and event pairs whose time difference is less than a preset time window are determined to be qualified measurement events.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] (1) Since the detection surface of the event-type delay line detector is divided into at least two independent event detection regions, and each region outputs event signals in parallel, when multiple electrons arrive at the detector simultaneously or sequentially, they can be assigned to different independent detection regions for parallel processing, instead of queuing in the same readout channel. This effectively avoids the event accumulation and readout conflict that are very likely to occur in traditional single-channel readout systems in multi-electron scenarios, significantly reduces the system dead time, and improves the event acquisition efficiency, thereby realizing parallel, low-dead-time readout of multi-electron events under angle resolution conditions.

[0031] (2) For the first time, multi-electron event coincidence measurement under angle-resolved conditions was achieved without changing the structure of the angle-resolved energy analyzer or sacrificing energy and momentum resolution. A unified triggering period was established as a global time reference through an external triggering and synchronization module. The time digitization readout module generated a timestamp containing the arrival time for each event signal. The data acquisition and processing module performed correlation selection based on timestamps from different regions within the same triggering period. Compared with existing solutions mentioned in the background art that rely on multiple discrete detectors (loss of angle resolution) or pump-probe scanning (complex system, low efficiency), this invention provides a simple, efficient, and angle-resolved multi-electron correlation measurement approach, achieving reliable multi-electron correlation while maintaining angle resolution.

[0032] (3) This invention does not simply connect multiple event outputs in parallel, but eliminates the inherent delay differences between different detection channels and electronic links through a precise calibration and compensation mechanism. The system supports an event time baseline calibration mode, in which the event arrival time distribution of each region is collected to obtain event time baseline information, and the inherent time delay between different detection regions is compensated based on this baseline information, so that the timestamps from different regions are in the same time coordinate system. This "unified time base calibration" mechanism is one of the core improvements of this invention, which ensures that the timestamps are comparable regardless of which detection region the event comes from. It realizes the compensation for the inherent delay between different detection channels, provides an accurate and reliable time basis for subsequent coincidence selection based on time windows, significantly reduces the probability of accidental coincidence, and improves the measurement signal-to-noise ratio.

[0033] (4) The coincidence measurement of the present invention does not depend on a specific time-domain structure of the light source. The system is correlated based on a unified trigger period signal and timestamp, and the trigger period can be flexibly set by an external trigger module according to the characteristics of the light source. It is applicable to pulsed light sources (such as synchrotron radiation and laser pulses), defining each light pulse as a trigger period; it is also applicable to continuous light sources (such as laboratory gas discharge lamps), using an external trigger module to generate periodic time windows for data binning. Compared with the pump-probe method mentioned in the background art, which is only applicable to pulsed light sources, this method has significantly wider applicability to light sources and greater experimental flexibility.

[0034] (5) The modules of this invention have clear functions and well-defined interfaces. They can be integrated with existing commercial ARPES systems and DLD detectors, and can also be expanded to more detection areas (such as four-segment or six-segment) or higher-order coincidence measurements (such as three-electron or four-electron coincidence) according to future experimental needs. This modular and scalable architecture gives this invention good engineering implementation value and long-term technical vitality. Attached Figure Description

[0035] Figure 1 This is an overall structural block diagram of the angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector of the present invention;

[0036] Figure 2 This is a schematic diagram of the multi-region parallel readout of the event-type detector of the present invention;

[0037] Figure 3 This is a schematic diagram of the external triggering and time digital synchronization of the present invention;

[0038] Figure 4 This is a schematic diagram of the event time baseline calibration mode of the present invention;

[0039] Figure 5 This is a schematic diagram of the multi-electron coincidence measurement mode of the present invention;

[0040] Figure 6 yes Figure 5 A schematic diagram of the event pair distribution results obtained under the condition τ=2 ns;

[0041] Figure 7 This is a schematic diagram of dual-channel time calibration under external triggering of the present invention;

[0042] Figure 8 This is a flowchart illustrating the angle-resolved multi-electron coincidence measurement method based on an event-type delay line detector according to the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] like Figure 1 As shown, the present invention provides an angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector, comprising: an angle-resolved energy analyzer, an event-type delay line detector, an external triggering and synchronization module, a time digitization readout module, and a data acquisition and processing module.

[0045] like Figure 8 As shown, the angle-resolved multi-electron coincidence measurement method of the above system includes the following steps:

[0046] Step S1: The photoelectrons emitted after the sample is irradiated by the excitation light source are energy and angle-resolved using an angle-resolved energy analyzer, and spatial dispersion is performed on the emission surface.

[0047] Step S2: At least two independent event detection regions of the event-type delay line detector set on the output surface of the angle-resolved energy analyzer are used to receive the dispersed photoelectrons in parallel and output the corresponding event signals independently.

[0048] Step S3: Generate a unified trigger cycle signal through the external triggering and synchronization module, and provide the trigger cycle signal to the excitation light source and the time digitization readout module respectively to establish a global time reference;

[0049] Step S4: Receive the event signal through the time digitization readout module, and generate a timestamp containing its arrival time for each event signal based on the unified trigger cycle signal;

[0050] Step S5: Receive event signals with the timestamps through the data acquisition and processing module, and perform correlation selection based on the timestamps of event signals from different event detection areas within the same triggering period, identifying multiple event signals that meet the preset time correlation conditions as qualified measurement events.

[0051] The angle-resolved energy analyzer is a hemispherical energy analyzer in this embodiment. It is used to receive photoelectrons emitted after the sample is irradiated by the excitation light source, and to perform spatial dispersion on the emission surface according to the energy and angle of the photoelectrons, so that photoelectrons with different energies and momentum fall at different positions on the emission surface.

[0052] It is understood that in other embodiments, the angle-resolved energy analyzer is not limited to a hemispherical analyzer, but can be other types of energy analyzers, such as cylindrical mirror analyzers, sector analyzers, etc.

[0053] The event-type delay line detector (DLD) is positioned on the exit surface of the angle-resolved energy analyzer. For example... Figure 2As shown, its detection surface is divided into two independent event detection regions (DLD_L and DLD_R), forming a dual-half-region structure. The two detection regions are used to receive dispersed photoelectrons in parallel and output their respective event signals independently. Each detection region is connected to its own readout / shaping unit (ACU1 and ACU2) to perform preliminary processing on the original event signals.

[0054] It should be noted that, in other embodiments, the number of detection regions of the event-type delay line detector is not limited to two, but may be three or more, to adapt to different experimental requirements or to achieve coincidence measurement of three or more electrons.

[0055] The external triggering and synchronization module is used to generate a unified triggering cycle signal. For example... Figure 3 As shown, the trigger period signal is divided into two paths: one path serves as the trigger / synchronization reference for the excitation source (such as a pulsed laser) to control the emission time of the light pulse; the other path is connected to the Start in or reference input of the Time Digital Readout Module (TDC) as a unified timing zero point for time measurement, thereby establishing a global time reference.

[0056] It should be noted that in other embodiments, the external triggering method can be periodic triggering or event triggering, depending on the type of excitation light source and experimental requirements.

[0057] The time digitization readout module is connected to each event detection region of the event-type delay line detector. In this embodiment, as... Figure 3 As shown, multiple event pulses from the left and right detection areas (DLD_L, DLD_R) are first precisely timed by constant-ratio timing discriminators (CFD1, CFD2) to eliminate timing errors caused by signal amplitude fluctuations, and then sent to different input channels (input1, input2) of the time-to-digital converter (TDC). The TDC digitizes the time of each input pulse within the same trigger cycle, generating a timestamp containing the arrival time for each event signal, forming an event list data structure, such as (startctr, x, y, t), where startctr is the trigger cycle number, x and y are the position coordinates of the event on the detector, and t is the timestamp relative to the trigger start point.

[0058] The data acquisition and processing module is connected to the time digitization readout module and is used to receive event signals with timestamps, and to organize, analyze and process the event signals.

[0059] It should be noted that, in other embodiments, the specific implementation of the time digitization readout module is not limited to the combination of CFD+TDC; any circuit or chip capable of achieving high-precision event time stamping can be used.

[0060] Combination Figure 4 and Figure 7 This document details the workflow of an angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector for performing event-time baseline calibration.

[0061] First, the system enters the event time baseline calibration mode. In this mode, the external triggering and synchronization module synchronously triggers the pulse light source and the time digitization readout module, precisely defining the moment of light pulse emission as the start moment of a measurement cycle.

[0062] The system has begun collecting data. For example... Figure 4 As shown, the arrival times t of the event signals in the left and right halves of the detection area (DLD_L and DLD_R) are statistically analyzed to obtain their respective arrival time distribution curves. By performing Gaussian fitting on these distribution curves, the time baseline t0 (i.e., the fitting center value) of each region can be accurately obtained. This baseline information reflects the average time from the emission of the light pulse to the recording of the event signal. The baseline difference between the left and right regions is Δt = |t L -t R This refers to the inherent delay difference between the two detectors and the electronic link. Figure 4 It can be seen that approximately 98% of the event signals arrive at the detector within an 80 ns time window, and there is a fixed deviation of approximately 1.885 ns in the time distribution center of the left and right half of the detection area.

[0063] like Figure 7As shown, the vertical line represents the starting point of the period of the external reference trigger signal ref; the peaks represent the arrival time distribution of the event signals recorded by channel A and channel B, respectively, and their peak values ​​(or centroids / fitting centers) correspond to the measured times tA and tB from ref to the arrival of the event signal. Due to the inherent delay difference between the two detectors and the electronic links, tA ≠ tB in the initial state. Based on the inherent delay difference obtained from calibration, the system compensates for it. The specific compensation method can be to set the channel delay parameters in the TDC, or to perform a shift correction on the timestamps in the data processing software. For example, firstly, a relative time shift Δt = |tA - tB| is applied to one of the channels to achieve time alignment between the channels, so that the measured times of the two channels are consistent, i.e., tA = tB. Then, while keeping tA = tB, a time shift Δt' can be applied to both channels to set the global time zero point of the system or the timing position for external synchronization triggering. Thus, the multi-channel unified time base calibration based on an external periodic reference is completed, so that the timestamps from different detection areas / channels are in the same time coordinate system, laying a precise time foundation for subsequent coincidence measurements.

[0064] This invention does not simply connect two parallel event detection outputs. Instead, it establishes a unified cycle starting point through an external reference trigger (ref) and provides inter-channel delay compensation and a global zero-point setting mechanism, ensuring that timestamps from different detection regions / channels are in the same time coordinate system. This unified time base calibration provides a prerequisite for subsequent pairing of event signals with the same cycle, cross-regional time difference criteria, and the comparability of data structures (startctr, x, y, t), thereby improving the time consistency, repeatability, and system stability of multi-region event signal measurements.

[0065] Combination Figure 5 This document details the workflow of an angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector for executing multi-electron coincidence measurement modes.

[0066] The system has completed baseline calibration, and the timestamps of all event signals are in a unified time base coordinate system. In this mode, the external triggering and synchronization module periodically activates the time digitization readout module to continuously collect photoelectron events from different detection areas under continuous or pulsed light source illumination of the sample.

[0067] After receiving the event stream (data structure: startctr, x, y, t), the data acquisition and processing module executes the following... Figure 5 The following is the filtering logic flow for matching event pairs:

[0068] Step 1: Bucket by Period: First, bucket the events according to the period number startctr, grouping all event signals arriving within the same trigger period into one group.

[0069] Step 2: Filter multiple event cycles: Count the number of event signals N in each trigger cycle, retain only the cycles with N≥2 for subsequent processing, and discard the cycles with fewer than 2 event signals.

[0070] Step 3: Generate candidate event pairs: Combine the event signals within the retention period in pairs to generate all possible candidate event pairs.

[0071] Step 4, Time Window Selection: For each candidate pair, calculate the arrival time difference of the event signal Δt = |t i - t j |. Set a time window τ (τ=2 ns in this embodiment). When the condition |Δt|<τ is met, output the event pair as a coupled (matching) event pair; otherwise, discard it.

[0072] Figure 6 A schematic diagram of the event signal pair distribution obtained under the condition τ=2 ns is shown. As can be seen from the figure, after time window filtering, the coincidence event pairs are spatially concentrated in the central region of the detector, indicating that this method can effectively extract correlated event signals arriving nearly simultaneously and suppress random coincidence background.

[0073] 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. An angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector, characterized in that, include: An angle-resolved energy analyzer is used to receive photoelectrons emitted after a sample is irradiated by an excitation light source, and to perform spatial dispersion on the emission surface based on the energy and angle of the photoelectrons. The angle-resolved energy analyzer is a hemispherical energy analyzer. An event-type delay line detector is disposed on the output surface of the angle-resolved energy analyzer. Its detection surface is divided into at least two independent event detection regions for receiving photoelectrons dispersed by the angle-resolved energy analyzer in parallel and outputting corresponding event signals independently. An external triggering and synchronization module is used to generate a unified triggering cycle signal and provide the triggering cycle signal to the excitation light source and the subsequent time digitization readout module to establish a global time reference. The time digitization readout module is connected to each event detection area of ​​the event-type delay line detector, and is used to receive the event signal and generate a timestamp for each event signal containing the time when the event signal arrives at the event detection area based on the unified trigger period signal. The data acquisition and processing module is connected to the time digitization readout module and is used to receive event signals with timestamps, and to perform correlation judgment based on the timestamps of event signals from different event detection areas within the same triggering period, and to identify multiple event signals that meet the preset time correlation conditions as conforming measurement events. The system supports an event time baseline calibration mode. In the event time baseline calibration mode, the external triggering and synchronization module synchronously triggers the excitation light source and the time digitization readout module, defines the light pulse emission time of the excitation light source as the start time of a measurement cycle, and collects the event signal arrival time distribution of each event detection area to obtain event time baseline information. Furthermore, the system compensates for the inherent time delay between the arrival times of event signals from different event detection areas based on the event time baseline information, so that the timestamps from different event detection areas are in the same time coordinate system.

2. The angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector according to claim 1, characterized in that, The time digitization readout module includes a constant fraction timer and a time-to-digital converter; The event signal is processed by the constant fraction timer and then sent to the time-to-digital converter to generate the timestamp.

3. The angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector according to claim 1, characterized in that, The system supports multiple electronic coincidence measurement modes; In the multi-electron coincidence measurement mode, the external triggering and synchronization module periodically activates the time digitization readout module to collect event signals from different event detection areas. Within the same triggering cycle, the data acquisition and processing module performs association and selection on multiple event signals based on the timestamp and according to the preset time association conditions to identify coincidence measurement events.

4. The angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector according to claim 3, characterized in that, The preset time association conditions include: combining the event signals in pairs within the same triggering period, calculating the time difference of each event signal pair, and determining the event signal pairs whose time difference is less than a preset time window as conforming measurement events.

5. The angle-resolved multi-electron coincidence measurement system based on an event-type delay line detector according to claim 1, characterized in that, The detection area of ​​the event-type delay line detector is divided into two independent event detection areas, forming a dual-half-zone structure.

6. An angle-resolved multi-electron coincidence measurement method based on an event-type delay line detector, applied to the system described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1: The photoelectrons emitted after the sample is irradiated by the excitation light source are energy and angle-resolved using an angle-resolved energy analyzer, and spatial dispersion is performed on the emission surface. Step S2: At least two independent event detection regions of the event-type delay line detector set on the output surface of the angle-resolved energy analyzer are used to receive the dispersed photoelectrons in parallel and output the corresponding event signals independently. Step S3: Generate a unified trigger cycle signal through the external triggering and synchronization module, and provide the trigger cycle signal to the excitation light source and the time digitization readout module respectively to establish a global time reference; Step S4: Receive the event signal through the time digitization readout module, and generate a timestamp containing its arrival time for each event signal based on the unified trigger cycle signal; Step S5: Receive event signals with the timestamps through the data acquisition and processing module, and perform correlation selection based on the timestamps of event signals from different event detection areas within the same triggering period, identifying multiple event signals that meet the preset time correlation conditions as qualified measurement events.

7. The angle-resolved multi-electron coincidence measurement method based on an event-type delay line detector according to claim 6, characterized in that, In step S5, events within the same triggering period are combined in pairs, the time difference of each event signal pair is calculated, and event pairs whose time difference is less than a preset time window are determined to be qualified measurement events.

Images