A hardware and software dual-integration test system for single photoelectron spectroscopy of photomultiplier tubes

Abstract

This invention discloses a hardware and software dual-integration testing system for single-photoelectron spectroscopy of photomultiplier tubes (PMTs), belonging to the field of PMT performance testing technology. The system includes a host computer control system, a pulsed light source and a light source driving system, a dark chamber testing station, a high-voltage power supply system, a transimpedance amplification module, a digital oscilloscope, an A / D conversion module, an FPGA module, and a database. The anode signal of the PMT under test, after passing through the transimpedance amplification module, enters both the software integration path of the digital oscilloscope and the hardware integration path composed of the A / D conversion module and the FPGA module. Both paths share the light source, high voltage, voltage divider, dark chamber station, and integration time window determination process. The host computer control system determines the integration time window based on the waveform, performs statistical analysis and fitting of the integrated event values, and obtains the single-photoelectron spectrum, peak-to-valley ratio, electron gain, and energy resolution. This invention combines complete waveform analysis and online integration under the same testing conditions and can be used for the automatic testing of PMTs of different tube types.

Description

Technical Field

[0001] This invention belongs to the field of photomultiplier tube performance testing technology, specifically relating to a hardware and software dual-integration testing system for single-photoelectron spectroscopy of photomultiplier tubes. Background Technology

[0002] Photomultiplier tubes (PMTs) utilize the external photoelectric effect and secondary electron emission to multiply signals, exhibiting high gain, low noise, and good time resolution. Single-photon emission spectra (SPES) are crucial for evaluating the dynamic performance of PMTs, providing key parameters such as peak-to-valley ratio, electron gain, and energy resolution. Existing SPES testing typically employs VME electronics systems or digital testing systems based on high-speed analog-to-digital converters (ADCs). VME electronics systems rely on dedicated modules and supporting instruments. Digital testing systems require external pulse generators, digital oscilloscopes, or digitizers; some systems also necessitate manual adjustment of the light source, setting of integration time windows, and switching of test parameters. When testing PMTs with different structures, such as end-window and side-window types, it is usually necessary to readjust the optical path, voltage divider, and time window parameters. Furthermore, existing testing platforms are generally built around either software integration or hardware integration, and the light sources, high voltages, voltage dividers, test stations, or test procedures used in these two methods are not entirely the same, making it difficult to switch and compare under identical conditions.

[0003] Therefore, providing a photomultiplier tube single photoelectron spectroscopy testing system that can simultaneously set software integration paths and hardware integration paths on the same platform, share test conditions and automatic test processes has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The technical problem to be solved by this invention is that existing single-photon emission spectrometry (SPES) testing systems are generally built around either software integration or hardware integration. The light sources, high voltages, voltage dividers, test stations, or test procedures used by the two methods are not exactly the same, making it difficult to switch and compare under the same conditions. At the same time, the position and width of the fixed integration time window are usually determined based on a small number of waveforms or manual experience, which makes it difficult to adapt to the transit time differences of different types of photomultiplier tubes.

[0005] To address the aforementioned technical problems, this invention provides a hardware and software dual-integration test system for single-photoelectron spectroscopy of photomultiplier tubes, comprising: a host computer control system, a pulsed light source and a light source driving system, a dark box test station, a high-voltage power supply system, a transimpedance amplification module, a digital oscilloscope, an A / D conversion module, an FPGA module, and a database. The dark box testing station is equipped with a photomultiplier tube under test and a replaceable voltage divider connected to the photomultiplier tube under test; The photomultiplier tube under test is illuminated by pulsed light generated by a pulsed light source and a light source driving system. The high-voltage power supply system is connected to a replaceable voltage divider. The anode output terminal of the photomultiplier tube under test is connected to the transimpedance amplifier module; The output of the transimpedance amplifier module is connected to a digital oscilloscope and an A / D conversion module, respectively. The digital oscilloscope is connected to the host computer control system; The A / D conversion module is connected to the host computer control system via the FPGA module; The host computer control system connects to the database; The transimpedance amplifier module, digital oscilloscope, and host computer control system constitute the software integration path; The transimpedance amplifier module, A / D conversion module, FPGA module, and host computer control system constitute the hardware integration path.

[0006] Furthermore, the host computer control system determines the waveform search interval based on the average transit time and transit time broadening of the photomultiplier tube under test, presets the search interval, uses the amplitude threshold to determine the pulse start position and pulse end position, and reserves sampling intervals at both ends of the pulse to form an integration time window.

[0007] Furthermore, the average transit time and transit time broadening are obtained in advance by the host computer control system under given light source intensity and operating voltage conditions.

[0008] Furthermore, for events where no obvious pulse is detected, the host computer control system selects a narrow time window for integration near the average arrival time of a single photon, and the width of the narrow time window is close to the average width of the anode pulse.

[0009] Furthermore, the digital oscilloscope acquires the anode waveform of the photomultiplier tube under test and transmits it to the host computer control system. The host computer control system performs numerical integration on the waveform sampling points within the integration time window.

[0010] Furthermore, the A / D conversion module converts the anode waveform into a digital waveform, and the FPGA module accumulates the digital sampling points according to the integration time window and sends the event integration quantity to the host computer control system.

[0011] Furthermore, the FPGA module generates pulse drive signals with adjustable frequency, duty cycle, and drive voltage. The host computer control system adjusts the light source drive voltage according to the proportion of single photoelectron events and the position of single photon peaks.

[0012] Furthermore, the replaceable voltage divider is installed in the dark chamber testing station in a plug-in manner, and is equipped with a high-voltage input interface and an anode signal output interface.

[0013] Furthermore, the host computer control system performs statistical analysis and fitting on the event integrals obtained from the two integration paths, calculates the peak-to-valley ratio, electronic gain, and energy resolution, and stores the test conditions and test results in the database.

[0014] Furthermore, the FPGA module includes: a host computer communication interface, a control register, a light source drive control unit, an A / D configuration and data reconstruction unit, a mode selection and data caching unit, a time window integration unit, and a result feedback unit.

[0015] Compared with the prior art, the present invention has the following advantages: (1) By setting the oscilloscope software integration path and the FPGA hardware integration path in the same test platform, the two paths share the light source, high voltage, voltage divider, dark box station, transimpedance amplifier module, integration time window determination process and single photon condition establishment process. The software integration path retains the complete waveform for easy algorithm analysis and result verification, while the hardware integration path is completed online by the FPGA for easy real-time processing. The two paths can be freely switched and mutually verified under the same test conditions. (2) By widening and limiting the pulse search range according to the average transit time and transit time of the photomultiplier tube, and determining the integration time window according to the actual start time and end time of the pulse in each trigger event, the integration interval is adjusted with the actual arrival position and pulse width of the pulse, reducing the effective pulse truncation and irrelevant baseline noise caused by fixed time window mismatch, and providing a spectral basis for the stable extraction of peak-to-valley ratio, electronic gain and energy resolution. (3) The FPGA module completes the light source drive control, A / D data reception, hardware integration and result caching, reducing the external pulse generator and repeated acquisition hardware, and simplifying the system structure. (4) The host computer completes the light source drive adjustment, path selection, data acquisition, spectral statistics, fitting, parameter calculation and database storage, realizing the automatic testing of single photoelectron spectrum of photomultiplier tubes with different structures. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the automatic testing process for a hardware and software dual-integration testing system for single-photoelectron spectroscopy of photomultiplier tubes.

[0017] Figure 2 This is a schematic diagram of the overall structure of a hardware and software dual-integration test system for single-photoelectron spectroscopy of a photomultiplier tube.

[0018] Figure 3 This is a functional structure block diagram of the FPGA module.

[0019] Figure 4 Comparison of single-photoelectron spectra of PVA2209 end-window photomultiplier tube under two integration paths.

[0020] Figure 5 Comparison of single-photoelectron spectra of PJ2013 side-window photomultiplier tube under two integration paths.

[0021] In the diagram: 1. Host computer control system; 2. Pulse light source and light source driving system; 3. Dark box test station; 4. Photomultiplier tube under test; 5. Replaceable voltage divider; 6. High voltage power supply system; 7. Transimpedance amplifier module; 8. Digital oscilloscope; 9. A / D conversion module; 10. FPGA module; 11. Database; 12. Host computer communication interface; 13. Control register; 14. Light source driving control unit; 15. A / D configuration and data reconstruction unit; 16. Mode selection and data buffer unit; 17. Time window integration unit; 18. Result feedback unit. Detailed Implementation

[0022] The technical solution of the present invention will be described below with reference to the accompanying drawings. The following embodiments are used to illustrate the composition, working process, and feasibility of the present invention, and are not intended to limit the scope of protection of the present invention. Equivalent substitutions made to device models, communication interfaces, sampling rates, integration time window parameters, and software implementation methods without departing from the technical concept of the present invention are all within the scope of protection of the present invention.

[0023] This invention provides a hardware and software dual-integration test system for single-photoelectron spectroscopy of photomultiplier tubes, which sets up an oscilloscope software integration path and an FPGA hardware integration path on the same test platform. The two paths share the same light source driver, high-voltage power supply, replaceable voltage divider, dark box test station, transimpedance amplification module, single-photon condition establishment process, and integration time window determination process, only changing the position of waveform acquisition and integral quantity calculation.

[0024] System overall structure; refer to Figure 2 This system consists of a host computer control system 1, a pulsed light source and light source driving system 2, a dark chamber testing station 3, a high-voltage power supply system 4, a transimpedance amplifier module 5, a digital oscilloscope 6, an A / D conversion module 7, an FPGA module 8, and a database 9. The photomultiplier tube under test (PMT) 3-1 is installed in the dark chamber testing station 3 and connected to a replaceable voltage divider 3-2. The replaceable voltage divider 3-2 is matched to the electrode structure of the PMT 3-1. The high-voltage power supply system 4 applies a high operating voltage to the replaceable voltage divider 3-2. The replaceable voltage divider 3-2 provides the required potential to the photocathode, each stage of the dynode, and the anode, and outputs the anode signal through the anode signal output interface.

[0025] The dark chamber testing station 3 employs a light-shielding structure and internally houses the photomultiplier tube under test (3-1), a replaceable voltage divider (3-2), and a pulsed light source. After installing the photomultiplier tube under test (3-1), the collimating optical path is adjusted so that the pulsed light source perpendicularly illuminates the photocathode surface. The replaceable voltage divider (3-2) is installed via a plug-in method. When testing end-window or side-window type photomultiplier tubes, a voltage divider matching the tube type is used, eliminating the need to replace the dark chamber, light source, and high-voltage power supply system. The purpose of providing the replaceable voltage divider (3-2) is that different photomultiplier tube structures have different electrode lead-out methods and voltage division ratio requirements. The replaceable voltage divider allows the system to adapt to different tube types without requiring a complete change of the testing station; only the corresponding voltage divider needs to be replaced.

[0026] The pulsed light source and light source driving system 2 employs a 405 nm pulsed laser diode, equipped with a collimating lens and a neutral density filter. The FPGA module 8 generates digital pulses with adjustable frequency and duty cycle, controlling the laser diode via a switching drive circuit. The pull-up voltage of the drive circuit is adjustable to change the output light intensity. An RC damping network is used to suppress overshoot and ringing caused by high-speed switching. The pulse drive signal also serves as a time reference; after a set delay, this signal triggers the digital oscilloscope 6 and serves as the search starting point for the integration time window. The pulse frequency is set within the range of 1 kHz to 20 kHz, with the specific value determined based on the photomultiplier tube under test and the sampling equipment.

[0027] The high-voltage power supply system 4 has functions for setting the operating high voltage, reading back the output voltage, and detecting the anode current, and communicates with the host computer control system 1. The high-voltage output range does not exceed 3000 V, the voltage setting resolution is 1 V, and the current detection resolution is 0.1 nA. A replaceable voltage divider 3-2 is provided with a high-voltage input interface and an anode signal output interface, and an energy storage capacitor is placed near the final stage electrode to reduce potential fluctuations in the voltage divider network during pulse output. The above specific ranges are used to illustrate possible implementations; the system can also select other high-voltage power supply devices and voltage divider networks that meet the requirements according to the type of tube under test.

[0028] The dual-integration path structure involves the photomultiplier tube under test (3-1) receiving its anode current pulse, which is first converted into a voltage pulse by a shared transimpedance amplifier module 5. The amplified signal then enters one of two selectable paths. In the software integration path, a digital oscilloscope 6 acquires the amplified anode waveform, and the host computer control system 1 performs numerical integration on the waveform. In the hardware integration path, the amplified voltage pulse is sent to an A / D conversion module 7, and an FPGA module 8 accumulates the digital sampling points. Both paths share the same components: the photomultiplier tube under test (3-1), a replaceable voltage divider 3-2, a pulse light source and light source drive system 2, a high-voltage power supply system 4, an dark box test station 3, and a transimpedance amplifier module 5. They employ the same light source drive voltage adjustment, single-photon condition judgment, and integration time window determination process. Path selection only changes the location of waveform acquisition and integration calculation.

[0029] The purpose of setting up dual integration paths is twofold: the software integration path preserves the complete waveform, facilitating algorithm analysis and result verification; the hardware integration path uses the FPGA for online integration, enabling real-time processing. Both can be freely switched and mutually verified under shared testing conditions, providing flexible options for different application needs.

[0030] Transimpedance amplifier module 5 converts the anode current pulse into a voltage pulse suitable for subsequent acquisition. The feedback resistor of the transimpedance amplifier circuit is 10 kΩ, ensuring that the pulse with a width of tens of nanoseconds retains its original time characteristics after amplification. The purpose of using a shared transimpedance amplifier module is to ensure that the input signals received by the two integration paths are exactly the same, eliminating system bias introduced by differences in amplifier circuits.

[0031] In the software integration path, digital oscilloscope 6 acquires the amplified anode waveform under external trigger conditions. Digital oscilloscope 6 employs a device supporting segmented storage, saving the waveform within each trigger cycle as a frame, reducing the storage space occupied by blank sampling data between pulses. The host computer control system 1 sets the sampling rate, storage depth, trigger source, and number of acquisition frames via the communication interface. The host computer reads each frame of discrete waveforms, determines the integration time window for each event, and performs numerical integration.

[0032] In the hardware integration path, the voltage pulse output from the transimpedance amplifier module 5 is fed into the A / D conversion module 7. The A / D conversion module 7 employs a high-speed analog-to-digital converter with a maximum sampling rate of 250 MSPS and a resolution of 12 bits. The high-speed differential data after A / D conversion is received by the FPGA module 8, and after deserialization, timing alignment, and data reconstruction, a single-channel digital waveform stream is formed. The above components and parameters can be replaced according to the amplitude, width, and accuracy requirements of the pulse under test.

[0033] Both the software and hardware integration paths characterize the output charge of a single event using the event integral within a time window. The discrete waveform obtained by the digital oscilloscope 6 is numerically integrated by the host computer control system 1, and the FPGA module 8 directly accumulates the A / D sampling points. When the sampling rate is sufficient and the integration time window completely covers the anode pulse, both integral quantities maintain a linear relationship with the pulse charge. Therefore, both paths use the same spectral statistics and parameter calculation methods. The software integration path retains the complete event waveform, facilitating observation and algorithm adjustment. The hardware integration path only transmits back the event integral quantity, facilitating online processing and system integration.

[0034] Determination of the integration time window: The process of determining the integration time window is as follows. The system uses the pulsed light source drive signal as a time reference. Under given light source intensity and operating voltage conditions, it acquires the average transit time and transit time broadening of the photomultiplier tube 3-1 under test, which serve as prior parameters for the integration time window search. The average transit time is used to provide the average delay of the single-photon pulse relative to the trigger signal, and the transit time broadening is used to provide the discrete range of the pulse arrival time. Both together define the position and width of the search interval. For each frame of waveform, within the preset search interval after triggering, the system searches for rising edges exceeding the noise floor based on an amplitude threshold, and takes the first sampling point near the threshold as the pulse start position. The system continues searching from the start position until the waveform falls back below the threshold, and takes the corresponding sampling point as the pulse end position. The system reserves approximately 5 ns sampling intervals before and after the pulse start position, respectively, forming an integration time window covering the complete single-photon pulse.

[0035] For events where no obvious pulse is detected, the system selects a narrow time window for integration near the average arrival time of a single photon. The width of this time window is close to the average width of the anode pulse, used to preserve the baseline noise statistics for zero photoelectron events. The software integration path adjusts the time window for each frame of waveform. The time window parameters of the hardware integration path are predetermined by the host computer based on the sample waveform and the type of tube under test, and then written into FPGA module 8.

[0036] Establishment of single-photon incident conditions: When establishing single-photon incident conditions, the host computer control system 1 first queries database 9 based on the tube type and tube number under test. If there are historical records in the database, the system reads the recommended initial light source driving voltage; if there are no historical records, the system uses the preset driving voltage. The system collects a small number of events under the current driving voltage to form a preliminary single-photon spectrum. The host computer adjusts the light source driving voltage in steps according to the proportion of single-photon events and the stability of the single-photon peak position. When the proportion of single-photon events reaches the preset condition and the single-photon peak position is basically stable within the continuous driving voltage range, the system determines the current light source driving parameters, which are stored in database 9 along with the tube type and tube number under test. The two integration paths share this adjustment process. The purpose of the two integration paths sharing the single-photon condition establishment process is to ensure that the test conditions remain unchanged after switching integration paths, and that the obtained single-photon spectra are comparable.

[0037] Automated testing process; refer to Figure 1 After the test begins, the host computer control system 1 checks the communication status of the high-voltage power supply system 4, the FPGA module 8, and the digital oscilloscope 6, and records the tube type, tube number, operating voltage, and integration path of the photomultiplier tube 3-1 under test. After the photomultiplier tube 3-1 is placed in a dark box to avoid light, the system applies the operating high voltage, turns on the pulsed light source, establishes the single-photon incident condition, and determines the integration time window. The system obtains the event integral quantity through the selected integration path, statistically forms the single-photon spectrum, and then completes the fitting and parameter calculation. After the test results are saved, the system turns off the light source and the high voltage.

[0038] The single-photon spectrum is fitted using a hybrid model of Gaussian and exponential functions. The host computer control system 1 determines the valley between the single-photon peak and the baseline peak based on the fitted curve. The ratio of the single-photon peak count to the valley count is the peak-valley ratio. The electron gain is obtained by subtracting the baseline peak noise charge from the average output charge of the single-photon peak and then dividing by the unit electron charge. The ratio of the full width at half maximum (FWHM) of the single-photon peak to the average charge is used to calculate the energy resolution. The software integration path and the hardware integration path use the same fitting and parameter calculation modules.

[0039] Internal structure of the FPGA module; see reference Figure 3The FPGA module 8 includes a host computer communication interface 8-1, a control register 8-2, a light source drive control unit 8-3, an A / D configuration and data reconstruction unit 8-4, a mode selection and data buffer unit 8-5, a time window integration unit 8-6, and a result feedback unit 8-7. The host computer sets the light source drive parameters, sampling parameters, and integration time window through the control register 8-2. After reconstruction, the A / D data enters the data buffer unit 8-5 and the time window integration unit 8-6. The event integration quantity is then sent to the host computer via the result feedback unit 8-7. Before the test begins, the host computer control system 1 writes the light source drive parameters, integration time window parameters, target event count, and operating mode into the FPGA module 8. The FPGA module 8 accumulates the digital sampling points of each event according to the set integration time window, writes the accumulated result as the event integration quantity into the first-in-first-out buffer, and transmits it back to the host computer control system 1 via the communication interface. The host computer verifies and parses the data, stops data acquisition after the number of events reaches the target value, performs frequency statistics on the integrated quantities of all events, and forms a single photoelectron spectrum under the hardware integration path. The functional division of FPGA module 8 is as follows: host computer communication interface 8-1 is responsible for command and data interaction with the host computer; control register 8-2 stores light source drive parameters, sampling parameters, and integration time window parameters; light source drive control unit 8-3 generates pulse drive signals according to the parameters in the control register; A / D configuration and data reconstruction unit 8-4 completes the configuration of the A / D converter and performs deserialization, alignment, and reconstruction of high-speed differential data; data buffer unit 8-5 buffers the reconstructed waveform data; mode selection and data buffer unit 8-5 switches between software integration mode and hardware integration mode, and buffers the reconstructed waveform data; time window integration unit 8-6 accumulates digital sampling points according to the integration time window in hardware integration mode; result feedback unit 8-7 encapsulates the event integration quantity and sends it to the host computer via host computer communication interface 8-1.

[0040] The host computer control system 1 includes an initialization module, an instrument control module, a single photoelectron spectroscopy (SPS) testing module, and a database module. The initialization module checks the communication connection and inputs test parameters. The instrument control module sets the pulse frequency, duty cycle, drive voltage, and operating high voltage, and reads the output voltage and anode current. The SPS testing module selects either the digital oscilloscope 6 or the FPGA module 8 based on the path selection to complete charge integration, frequency statistics, fitting, and parameter calculation. The database module saves test time, tube type, tube number, operating voltage, light source parameters, spectral lines, and performance parameters, and also provides historical parameter query and result export functions.

[0041] Verification experiments were conducted to verify the system's feasibility. A PVA2209 end-window photomultiplier tube and a PJ2013 side-window photomultiplier tube were selected as test subjects. The driving frequency of the pulsed laser diode was set to 10 kHz, and the duty cycle to 0.01%. A neutral density filter with a transmittance of 0.1% was used in the optical path. The host computer automatically adjusted the light source driving voltage for both types of tubes under test, ensuring that the proportion of single-photoelectron events in the responding events exceeded 95%. Approximately 600,000 waveforms or event integrals were accumulated in each test to form the single-photoelectron spectrum.

[0042] Under the conditions of a PVA2209 end-window photomultiplier tube operating at 1250 V and a light source driving voltage of 2.436 V, and a PJ2013 side-window photomultiplier tube operating at 1000 V and a light source driving voltage of 2.224 V, the single-photoelectron spectra obtained by the two integration paths are as follows: Figure 4 and Figure 5 As shown. (Refer to...) Figure 4 The PVA2209 end-window photomultiplier tube yielded clear single-photoelectron spectrum curves under both software and hardware integration paths; (Refer to...) Figure 5 The PJ2013 side-window photomultiplier tube yielded clear single-photon spectrum curves under both software and hardware integration paths. Both types of tubes exhibited distinct baseline and single-photon peaks, enabling the distinction between single-photon events and baseline noise events. The single-photon spectrum obtained via the hardware integration path showed an overall rightward shift compared to the software integration path.

[0043] In the software integration path repeatability test, the relative errors of peak-to-valley ratio, electronic gain, and energy resolution for the PVA2209 end-window photomultiplier tube were 3.18%, 2.19%, and 2.71%, respectively, while those for the PJ2013 side-window photomultiplier tube were 5.08%, 5.35%, and 2.79%, respectively, all less than 6%. In the hardware integration path repeatability test, the relative errors of the three parameters for the PVA2209 end-window photomultiplier tube were 3.91%, 3.23%, and 1.79%, respectively, while those for the PJ2013 side-window photomultiplier tube were 4.53%, 0.37%, and 3.62%, respectively, all less than 5%.

[0044] Under the same operating voltage and light source test conditions, the average peak-to-valley ratio of the PVA2209 end-window photomultiplier tube via software integration path is 2.170, and the average electronic gain is 2.4145 × 10⁻⁶. 7 The average energy resolution is 54.291%, and the corresponding results for the hardware integration path are 2.386 and 2.6226 × 10⁻⁶. 7And 54.900%. The average peak-to-valley ratio of the software integration path of the PJ2013 side-window photomultiplier tube is 1.628, and the average electronic gain is 1.8827 × 10⁻⁶. 7 The average energy resolution is 64.235%, and the corresponding results for the hardware integration path are 1.861 and 2.0478 × 10⁻⁶. 7 And 62.906%. The spectral lines and parameter changes obtained from the two paths are consistent. The software integration path retains the original waveform, while the hardware integration path completes online integration.

[0045] The average electronic gain of the two photomultiplier tube types under the hardware integration path was approximately 8.6% and 8.8% higher than that under the software integration path, respectively. Both test paths integrate the single photoelectron pulses output by the photomultiplier tube and convert the single photoelectron charge using the input impedance to further calculate the electronic gain. Therefore, the difference in integration path does not change the gain of the photomultiplier tube itself. The software integration path directly acquires the signal using a digital oscilloscope, and its input impedance parameters are clearly defined. In the hardware integration path, the signal needs to pass through a front-end impedance network, transimpedance amplification, and A / D conversion before integration is completed by the FPGA. The actual equivalent impedance, hardware link conversion gain, and device parameter deviations introduce proportional systematic errors during charge conversion. Because a standard known charge signal was not used to calibrate the hardware link during testing, the absolute electronic gain obtained by the two paths differs as described above. However, the repeatability test results for each path show that both paths can stably complete single photoelectron spectrum testing and related parameter extraction.

[0046] The test results of this system were also compared with those of VME electronics. In the VME electronics test, the repeatability errors for peak-to-valley ratio, electron gain, and energy resolution were 3.41%, 1.99%, and 2.92%, respectively. The test results of the two integration paths of this system showed good consistency with the VME electronics test results, indicating that this system can be used for automatic single-photoelectron spectroscopy testing of photomultiplier tubes with different structures.

Claims

1. A hardware and software dual-integration test system for single-photoelectron spectroscopy of a photomultiplier tube, characterized in that, include: The system comprises a host computer control system (1), a pulse light source and a light source driving system (2), an dark box testing station (3), a high-voltage power supply system (4), a transimpedance amplifier module (5), a digital oscilloscope (6), an A / D conversion module (7), an FPGA module (8), and a database (9), among which, The dark box test station (3) is equipped with a photomultiplier tube (3-1) to be tested and a replaceable voltage divider (3-2) connected to the photomultiplier tube (3-1). The pulsed light generated by the pulsed light source and the light source driving system (2) irradiates the photomultiplier tube under test (3-1). The high-voltage power supply system (4) is connected to a replaceable voltage divider (3-2); The anode output terminal of the photomultiplier tube (3-1) under test is connected to the transimpedance amplifier module (5). The output of the transimpedance amplifier module (5) is connected to the digital oscilloscope (6) and the A / D conversion module (7), respectively. The digital oscilloscope (6) is connected to the host computer control system (1). The A / D conversion module (7) is connected to the host computer control system (1) via the FPGA module (8). The host computer control system (1) connects to the database (9); The FPGA module (8) generates a pulse drive signal, which triggers the digital oscilloscope (6) after a set delay. The transimpedance amplifier module (5), the digital oscilloscope (6), and the host computer control system (1) constitute the software integration path; The transimpedance amplifier module (5), the A / D conversion module (7), the FPGA module (8), and the host computer control system (1) constitute the hardware integration path.

2. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 1, characterized in that, The host computer control system (1) determines the waveform search interval based on the average transit time and transit time broadening of the photomultiplier tube (3-1) under test, sets the preset search interval, determines the pulse start position and pulse end position using the amplitude threshold, and reserves the sampling interval at both ends of the pulse to form an integration time window.

3. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 2, characterized in that, The average transit time and transit time broadening are obtained in advance by the host computer control system (1) under given light source intensity and operating voltage conditions.

4. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 2, characterized in that, For events where no obvious pulse is detected, the host computer control system (1) selects a narrow time window for integration near the average arrival time of a single photon, and the width of the narrow time window is close to the average width of the anode pulse.

5. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 2, characterized in that, The digital oscilloscope (6) acquires the anode waveform of the photomultiplier tube (3-1) under test and transmits it to the host computer control system (1). The host computer control system (1) performs numerical integration on the waveform sampling points within the integration time window.

6. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 2, characterized in that, The A / D conversion module (7) converts the anode waveform into a digital waveform, and the FPGA module (8) accumulates the digital sampling points according to the integration time window and sends the event integration amount to the host computer control system (1).

7. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 1, characterized in that, The FPGA module (8) generates pulse drive signals with adjustable frequency, duty cycle and drive voltage. The host computer control system (1) adjusts the light source drive voltage according to the proportion of single photoelectron events and the position of single photon peaks.

8. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 1, characterized in that, The replaceable voltage divider (3-2) is installed in the dark box test station (3) in a plug-in manner, and is equipped with a high voltage input interface and an anode signal output interface.

9. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 1, characterized in that, The host computer control system (1) performs statistics and fitting on the event integrals obtained from the two integral paths, calculates the peak-to-valley ratio, electronic gain and energy resolution, and stores the test conditions and test results in the database (9).

10. The photomultiplier tube single-photoelectron spectroscopy hardware and software dual-integration test system according to claim 1, characterized in that, The FPGA module (8) includes: host computer communication interface (8-1), control register (8-2), light source drive control unit (8-3), A / D configuration and data reconstruction unit (8-4), mode selection and data caching unit, data caching unit (8-5), time window integration unit (8-6), and result feedback unit (8-7).

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