CN-121994849-A - Angular resolution multi-electronic coincidence measurement system and method based on event type delay line detector

CN121994849ACN 121994849 ACN121994849 ACN 121994849ACN-121994849-A

Abstract

The invention relates to the technical field of angle-resolved photoelectron spectroscopy experimental instruments, and discloses an angle-resolved multiple-electron coincidence measurement system and method based on an event-type delay line detector, wherein the system comprises an angle-resolved energy analyzer; the system comprises an event type delay line detector, an external triggering and synchronizing module, a time digital reading module and a data acquisition and processing module, wherein the detection surface of the event type delay line detector is divided into at least two independent areas and is used for receiving photoelectrons in parallel and independently outputting event signals, the external triggering and synchronizing module is used for generating a unified triggering period to establish a global time reference, the time digital reading module is used for receiving the event signals and generating time stamps, and the data acquisition and processing module is used for carrying out association judgment and selection based on the time stamps in the same triggering period. The invention reduces dead time through multi-region parallel reading, realizes unified time base calibration through time base calibration and delay compensation, can realize multi-electronic coincidence measurement under the condition of keeping angular resolution, and is suitable for pulse or continuous light sources.

Inventors

Chen Congrun
CAO YUEHAN
Xiu Zhaoyu
YAO WEI
LIU WANLING
SUN YUJIE
WANG XIAOPING
SHAN XINYAN

Assignees

南方科技大学

Dates

Publication Date: 20260508
Application Date: 20260407

Claims (10)

1. An event-based delay line detector-based angle-resolved multiple-electron coincidence measurement system, comprising: The angle resolution energy analyzer is used for receiving photoelectrons emitted after the sample is irradiated by the excitation light source and carrying out space dispersion on an emitting surface according to the energy and the angle of the photoelectrons; the event type delay line detector is arranged on the emergent surface of the angle-resolved energy analyzer, the detection surface of the event type delay line detector is divided into at least two mutually independent event detection areas and is used for receiving photoelectrons dispersed by the angle-resolved energy analyzer in parallel and outputting corresponding event signals respectively and independently; the external triggering and synchronizing module is used for generating a unified triggering period signal and respectively providing the triggering period signal for the excitation light source and the subsequent time digital reading module so as to establish a global time reference; The time digital reading module is connected with each event detection area of the event type delay line detector and is used for receiving the event signals and generating a time stamp containing the time when the event signals reach the event detection area for each event signal based on the unified trigger period signals; The data acquisition and processing module is connected with the time digital reading module and is used for receiving event signals with time stamps, carrying out relevance judgment on the basis of the time stamps of the event signals from different event detection areas in the same trigger period and identifying a plurality of event signals meeting preset time relevance conditions as being in line with a measurement event.
2. The system for angular resolved multiple electronic coincidence measurement based on an event type delay line detector of claim 1 wherein said time digitizing readout module includes a constant fraction timer and a time digitizer; and the event signal is sent to the time-to-digital converter after being subjected to timing processing by the constant fraction timer so as to generate the time stamp.
3. The system for angle-resolved multiple electronic coincidence measurement based on an event-type delay line detector of claim 1, wherein the system supports an event time baseline calibration mode; And in the event time base line calibration mode, the external triggering and synchronizing module synchronously triggers the excitation light source and the time digital reading module, the light pulse transmitting moment of the excitation light source is defined as the starting moment of a measurement period, and the arrival time distribution of event signals of each event detection area is acquired to obtain event time base line information.
4. The system for angle-resolved multiple electronic coincidence measurement based on an event type delay line detector of claim 3, wherein the system compensates for inherent time delays between arrival times of event signals from different ones of the event detection regions based on the event time baseline information such that the time stamps from different ones of the event detection regions are in the same time coordinate system.
5. The event-based delay line detector-based angle-resolved multiple-electron coincidence measurement system of claim 1, wherein the system supports multiple-electron coincidence measurement modes; And in the multi-electronic coincidence measurement mode, the external triggering and synchronizing module periodically starts the time digital reading module to acquire the event signals from different event detection areas, and the data acquisition and processing module carries out association judgment on a plurality of event signals according to the preset time association condition in the same triggering period based on the time stamp so as to identify coincidence measurement events.
6. The system of claim 5, wherein the predetermined time-related condition comprises combining the event signals in the same trigger period in pairs, calculating a time difference for each of the event signal pairs, and determining the event signal pairs having a time difference less than a predetermined coincidence time window as coincidence measurement events.
7. The system of claim 1, wherein the detection area of the event-based delay line detector is divided into two independent event detection areas to form a two-half structure.
8. The system of claim 1, wherein the angle-resolved multiple electron coincidence measurement system is a hemispherical energy analyzer.
9. An angular resolved multiple electron coincidence measurement method based on an event type delay line detector, applied to the system of any of claims 1 to 8, comprising the steps of: S1, carrying out energy and angle resolution on photoelectrons emitted after a sample is irradiated by an excitation light source through an angle resolution energy analyzer, and carrying out space dispersion on an emission surface; S2, receiving dispersed photoelectrons in parallel through at least two mutually independent event detection areas of an event type delay line detector arranged on an emergent surface of the angular resolution energy analyzer, and outputting corresponding event signals respectively and independently; Step S3, generating a unified trigger period signal through an external trigger and synchronization module, and respectively providing the trigger period signal for the excitation light source and the time digital readout module to establish a global time reference; Step S4, receiving the event signals through the time digital readout module, and generating a time stamp containing the arrival time of each event signal based on the unified trigger period signals; And S5, receiving event signals with the time stamps through a data acquisition and processing module, performing relevance judgment and selection based on the time stamps of the event signals from different event detection areas in the same trigger period, and identifying a plurality of event signals meeting preset time relevance conditions as being in line with a measurement event.
10. The method for angle-resolved multiple-electron coincidence measurement based on an event type delay line detector according to claim 9, wherein in the step S5, events in the same trigger period are combined two by two, a time difference of each event signal pair is calculated, and the event pair with the time difference smaller than a preset coincidence time window is determined as a coincidence measurement event.

Description

Angular resolution multi-electronic coincidence measurement system and method based on event type delay line detector Technical Field The invention relates to the technical field of angle-resolved photoelectron spectroscopy experimental instruments, in particular to a detection system and method for multi-electron coincidence measurement. Background Angle-resolved photoelectron spectroscopy (ARPES) is one of the most direct and powerful experimental techniques for studying the structure of the electron energy band of materials in contemporary condensed state physics and materials science. The basic principle is based on photoelectric effect, and the energy-momentum dispersion relation of electrons in the material is directly obtained by measuring the kinetic energy of photoelectrons with different emergent angles. In existing conventional ARPES measurements, detection systems mostly employ integrated or single channel event-integrated readout schemes. The core of these schemes is to make a temporal and spatial cumulative statistics of a large number of optoelectronic events over a fixed acquisition window, thereby generating a two-dimensional image (e.g., an energy vs. momentum profile) reflecting the energy band structure. However, the above conventional detection methods expose significant technical drawbacks when experimental studies are extended from single particle behavior to multi-particle correlation effects (such as double photoelectron emission, auger electron cascade, coulomb decay, etc.). In a multiple electron measurement scenario, multiple photoelectrons may arrive at the detector simultaneously or sequentially within the same excitation pulse or within a short coherence window of the same continuous light source. For an integral detection system, multiple events may overlap spatially or temporally, resulting in signal superposition, failure to distinguish between individual events, and loss of information. For the traditional single-channel event reading system, due to dead time, when multiple events are in a short time, event accumulation and reading conflict are very easy to occur, so that time information of subsequent events is lost or cannot be accurately recorded. To study the correlation between electrons, the prior art developed a coincidence measurement method. These methods typically rely on the detection of multiple outgoing electrons using multiple independent detectors or employing pump-detection (pump-probe) techniques in combination with ultrafast time delay scanning to construct the time correlation. However, these prior approaches have the limitations that, although coincidence can be achieved over time using multiple discrete detectors, generally only a limited solid angle is covered, the ability to energy-momentum map is completely lost, and no angular resolution of the electrons is given. The ultra-fast time scanning method based on pump-detection can obtain extremely high time resolution, but the experimental system is complex, the acquisition efficiency is low, and the method is mainly applicable to tunable pulse light sources and is difficult to apply to synchronous radiation or laboratory conventional continuous light sources. Furthermore, in a multi-channel event readout system, there is inevitably an inherent delay difference between the different detection channels and their subsequent electronics links. If these differences are not corrected, electronic events from the same excitation process but detected by different areas will have their time stamps in different time coordinate systems, resulting in a deviation or failure of subsequent time-dependent decisions. In summary, there is still a lack of a measurement scheme in the prior art that can effectively read out multiple electronic events concurrently and uniformly calibrate the time difference between multiple channels while maintaining the energy and momentum resolving power necessary for the conventional ARPES experiment, so as to reliably realize time correlation discrimination between multiple electronic events. How to realize parallel, low dead time reading, multi-channel unified time base calibration and high-precision time correlation analysis of multiple electronic events on a detection plane with angle and energy resolution is a technical problem to be solved in the field. Disclosure of Invention Aiming at the defects of the prior art, the invention provides an angle resolution multi-electron coincidence measurement system and method based on an event type delay line detector, which are difficult to realize the reliable coincidence measurement of multi-electron events while maintaining the energy and momentum resolution capability in the existing angle resolution photoelectron spectroscopy system. In order to achieve the above purpose, the invention adopts the following technical scheme: In a first aspect, the present invention provides an angle-resolved multiple-electron coincidence measurement syste