Detection and Compensation Device for Radiation Damage Effect of Silicon Photomultiplier

Abstract

The present disclosure relates to a detection and compensation device for the irradiation damage effect of a silicon photomultiplier. The anode voltage of the silicon photomultiplier is collected by a voltage adjustment module to obtain the dark current of the silicon photomultiplier. When the bias voltage at both ends of the silicon photomultiplier deviates from the target bias voltage by a preset range, the output voltage of the power supply module is adjusted so that the bias voltage at both ends of the silicon photomultiplier is within the preset range of the target bias voltage, thereby realizing the detection of the dark current of the silicon photomultiplier and the compensation of the bias voltage at both ends of the SiPM. The signal acquisition module is used to measure the dark count noise of the silicon photomultiplier, and the signal acquisition trigger threshold of the signal acquisition module is adaptively adjusted according to the measured noise, so that the signal acquisition module performs signal acquisition when the amplitude of the signal transmitted from the first capacitor is greater than or equal to the signal acquisition trigger threshold, reducing the probability of noise mis-triggering.

Description

Technical Field

[0001] The present disclosure relates to the technical field of silicon photomultipliers, and particularly to a detection and compensation device for the irradiation damage effect of a silicon photomultiplier. Background Art

[0002] Silicon photomultiplier (SiPM) is a new type of photoelectric conversion device with the advantages of low bias voltage, compact size, and insensitivity to magnetic fields. It can replace photomultiplier tubes and couple with scintillators to form high-energy particle detectors. It has been widely studied and applied in the fields of high-energy physics and astrophysics. For example, the compact muon solenoid (CMS) detector in the Large Hadron Collider (LHC) at the European Organization for Nuclear Research uses SiPM as the photoelectric conversion device of the scintillator on the hadron calorimeter [Artur Lobanov and (for the CMS Collaboration) 2015 J. Phys.: Conf. Ser. 587 01 2005], and my country's space science satellite hard X-ray modulation telescope (HXMT, Insight Satellite) [Nuclear Inst. and Methods in Physics Research, A 822 (2016) 63–70] and gravitational wave burst high-energy electromagnetic counterpart all-day monitor (GECAM satellite, Huairou No. 1) [Nuclear Inst. and Methods in Physics Research, A 921 (2019) 8–13] also use SiPM as the photoelectric conversion device of the scintillator. In addition, the track detector of the LHC bottom quark experiment (Large Hadron Collider beauty, LHCb) [Nuclear Inst. and Methods in Physics Research, A958 (2020) 162025], as well as many other space science satellite projects, such as GRID [Experimental Astronomy (2019) 48: 77–95], SIRI [Proc. SPIE 10397, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX, 103970B (29 August 2017)], and GRB Alpha ["Proc. SPIE 11444, Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray, 114444V (13 December 2020)], all use SiPM as a scintillator photoelectric conversion device.

[0003] Among these detectors, commonly used SiPM power supply and signal readout methods are as follows Figure 1As shown in [NUCL SCI TECH(2021)32:99], a power supply provides a bias voltage of dozens of volts. After being filtered by a resistor and a capacitor, it powers the SiPM. Due to thermal excitation and other factors, the SiPM continuously generates dark count signals, which will flow directly into the ground through the resistor in the direct current path in the form of a direct current signal. The resistor in this direct current path also plays a role in limiting the total current flowing through the SiPM, preventing the situation where the power supply is damaged due to excessive output current caused by the damage of the SiPM. The instantaneous light emission signal of the scintillator received by the SiPM will enter the readout circuit through the AC coupling capacitor.

[0004] However, a key problem faced during the use of SiPM is the impact of radiation damage effects on its performance. When SiPM is used in high-energy physics experimental environments and space environments, it usually undergoes high-flux high-energy particle radiation, resulting in radiation damage effects. The main manifestation is that after the SiPM is irradiated by high-flux high-energy particles, the dark count rate (DCR) increases. The relationship between the dark count rate DCR and the dark current I d is: I d = DCR×∫h(t), where h(t) represents the single-photon signal pulse, and ∫h(t) represents the single-photon signal charge amount, which is proportional to the gain G of the SiPM. When the gain of the SiPM is constant, the radiation damage effect will increase the dark current of the SiPM.

[0005] The equivalent voltage noise v nSiPM of the SiPM can be expressed as where h(t) represents the single-photon signal pulse and DCR represents the dark count rate. Therefore, the radiation damage effect will increase the noise level of the SiPM, affecting the readout and acquisition of normal signals. Moreover, as the dark current of the SiPM increases, the voltage drops across the current-limiting resistor and the filtering resistor will also increase, thereby changing the actual bias voltage value across the SiPM, thus affecting the stability of the SiPM gain. Summary of the Invention

[0006] According to one aspect of the present disclosure, a detection and compensation device for the radiation damage effect of a silicon photomultiplier is provided. The device includes a power supply module, a filtering module, a current-limiting resistor module, a first capacitor, a silicon photomultiplier, a voltage adjustment module, and / or a signal acquisition module, where

[0007] The power supply module includes at least one voltage output terminal. The voltage output terminal is connected to the cathode of the silicon photomultiplier through the filtering module, and the anode of the silicon photomultiplier is grounded through the current-limiting resistor module.

[0008] The voltage adjustment module is connected to at least one of the common node of the silicon photomultiplier tube and the filtering module, the common node of the silicon photomultiplier tube and the current limiting resistor module, and the common node of the voltage output terminal and the filtering module. The voltage adjustment module is used to collect the voltage difference across the filtering module or the voltage difference across the current limiting resistor module to obtain the dark current of the silicon photomultiplier tube, and adjust the output voltage of the power supply module when the bias voltage across the silicon photomultiplier tube deviates from the target bias voltage by a preset range, so that the bias voltage across the silicon photomultiplier tube is within the preset range of the target bias voltage;

[0009] The signal acquisition module is connected to the anode of the silicon photomultiplier tube through the first capacitor, and is used to measure the dark count noise of the silicon photomultiplier tube, and adaptively adjust the signal acquisition trigger threshold of the signal acquisition module according to the measured noise. The signal acquisition module is also used to perform signal acquisition when the amplitude of the signal transmitted by the first capacitor is greater than or equal to the signal acquisition trigger threshold.

[0010] In a possible implementation manner, collecting the voltage difference across the filtering module or the voltage difference across the current limiting resistor module to obtain the dark current of the silicon photomultiplier tube includes: determining the dark current of the silicon photomultiplier tube according to the voltage difference across the filtering module and the equivalent resistance of the filtering module; or determining the dark current of the silicon photomultiplier tube according to the voltage difference across the current limiting resistor module and the resistance of the current limiting resistor module;

[0011] The voltage adjustment module is further used for:

[0012] Determining the voltage drop of the filtering module according to the dark current and the equivalent resistance of the filtering module;

[0013] Determining the bias voltage across the silicon photomultiplier tube according to the output voltage of the power supply module, the voltage drop of the filtering module, and the anode voltage.

[0014] In a possible implementation manner, the voltage adjustment module includes a first control unit, a first voltage acquisition unit, a second voltage acquisition unit, and a third voltage acquisition unit. The first voltage acquisition unit, the second voltage acquisition unit, and the third voltage acquisition unit all include a voltage follower and an analog-to-digital converter, where,

[0015] The input end of the first voltage acquisition unit is connected to the common node of the voltage output terminal and the filtering module, and the output end of the first voltage acquisition unit is connected to the first input end of the first control unit,

[0016] The input end of the second voltage acquisition unit is connected to the common node of the silicon photomultiplier tube and the current limiting resistor module, and the output end of the second voltage acquisition unit is connected to the second input end of the first control unit.

[0017] The input end of the third voltage acquisition unit is connected to the common node of the silicon photomultiplier tube and the filtering module, and the output end of the third voltage acquisition unit is connected to the third input end of the first control unit.

[0018] The output end of the first control unit is connected to the power supply module and is used to perform at least one of the following:

[0019] Obtain the dark current according to the voltage difference across the current limiting resistor module collected by the second voltage acquisition unit and the resistance of the current limiting resistor module;

[0020] Determine the dark current of the silicon photomultiplier tube according to the voltage of the common node of the silicon photomultiplier tube and the filtering module collected by the third voltage acquisition unit, the output voltage of the power supply module collected by the first voltage acquisition unit, and the equivalent resistance of the filtering module;

[0021] Determine the voltage drop of the filtering module according to the dark current and the equivalent resistance of the filtering module;

[0022] Determine the bias voltage across the silicon photomultiplier tube according to the output voltage of the power supply module collected by the first voltage acquisition unit, the voltage drop of the filtering module, and the voltage difference across the current limiting resistor module, and adjust the output voltage of the power supply module when the bias voltage across the silicon photomultiplier tube deviates from the target bias voltage by a preset range, so that the bias voltage across the silicon photomultiplier tube is within the preset range of the target bias voltage.

[0023] In a possible implementation manner, measuring the dark count noise of the silicon photomultiplier tube and adaptively adjusting the signal acquisition trigger threshold of the signal acquisition module according to the measured noise, and performing signal acquisition when the amplitude of the signal from the first capacitor is greater than or equal to the signal acquisition trigger threshold includes:

[0024] Disconnect the power supply to the silicon photomultiplier tube, input a test signal at the second end of the first capacitor, and obtain the electronic noise of the signal acquisition module;

[0025] Restore the power supply to the silicon photomultiplier tube, input a test signal at the second end of the first capacitor, and obtain the overall noise, where the overall noise includes the electronic noise and the dark count noise of the silicon photomultiplier tube;

[0026] Determine the dark count noise of the silicon photomultiplier based on the overall noise and the electronics noise;

[0027] Set the acquisition trigger threshold of the signal acquisition module to a preset multiple of the overall noise, where the preset multiple is greater than 3.

[0028] In a possible implementation, the preset multiple is 6.

[0029] In a possible implementation, the signal acquisition module includes a second control unit, a switch unit, a second capacitor, a signal processing unit, a digital-to-analog conversion unit, a trigger, and an acquisition unit, where

[0030] The first output terminal of the second control unit is connected to the second terminal of the first capacitor and the input terminal of the signal processing unit through the switch unit and the second capacitor,

[0031] The second output terminal of the second control unit is connected to the trigger through the digital-to-analog conversion unit,

[0032] The output terminal of the signal processing unit is connected to the input terminal of the trigger and the input terminal of the acquisition unit,

[0033] The control terminal of the acquisition unit is connected to the output terminal of the trigger, and the output terminal of the acquisition unit is connected to the input terminal of the second control unit,

[0034] Among them, the second control unit is used to output a switch control signal to control the conduction state of the switch unit to change, so that the voltage across the second capacitor changes, thereby inputting the test signal to the input terminal of the signal processing unit,

[0035] The signal processing unit is used to perform voltage conversion on the received signal and output an intermediate voltage signal,

[0036] The trigger is used to trigger the acquisition unit to acquire a signal when the voltage amplitude of the intermediate voltage signal is greater than or equal to the acquisition trigger threshold of the trigger, where the acquisition trigger threshold of the trigger is set by the second control unit through the digital-to-analog conversion unit,

[0037] The acquisition unit is used to perform analog-to-digital conversion on the acquired intermediate voltage signal and output it to the second control unit.

[0038] In a possible implementation, the switch unit includes an analog switch, the signal processing unit includes a multi-stage amplifier circuit, and the acquisition unit includes a peak hold circuit and an analog-to-digital converter.

[0039] An embodiment of the present disclosure provides a detection and compensation device for the irradiation damage effect of a silicon photomultiplier tube. The device includes a power supply module, a filtering module, a current limiting resistor module, a first capacitor, a silicon photomultiplier tube, a voltage adjustment module, and / or a signal acquisition module. The voltage difference across the filtering module or the current limiting resistor module is collected through the voltage adjustment module to obtain the dark current of the silicon photomultiplier tube. When the bias voltage across the silicon photomultiplier tube deviates from the target bias voltage by a preset range, the output voltage of the power supply module is adjusted so that the bias voltage across the silicon photomultiplier tube is within the preset range of the target bias voltage, thereby realizing the detection of the dark current of the silicon photomultiplier tube and the compensation of the bias voltage across the SiPM. The signal acquisition module is used to measure the dark count noise of the silicon photomultiplier tube, and the signal acquisition trigger threshold of the signal acquisition module is adaptively adjusted according to the measured noise. Thus, when the amplitude of the signal transmitted from the first capacitor is greater than or equal to the signal acquisition trigger threshold, the signal acquisition module performs signal acquisition.

[0040] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and do not limit the present disclosure. According to the following detailed description of the exemplary embodiments with reference to the accompanying drawings, other features and aspects of the present disclosure will become clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings herein are incorporated into the specification and form a part of this specification. These drawings illustrate embodiments consistent with the present disclosure and, together with the specification, are used to explain the technical solutions of the present disclosure.

[0042] Figure 1 Schematic diagram of the SiPM power supply and signal readout circuit in the related art.

[0043] Figure 2 Schematic diagram of the SiPM irradiation damage effect detection device based on the dark count rate measurement in the related art.

[0044] Figure 3 Schematic diagram of the SiPM radiation damage effect detection device based on a multimeter or an ammeter in the related art.

[0045] Figure 4 Schematic diagram of the detection and compensation device for the irradiation damage effect of a silicon photomultiplier tube according to an embodiment of the present disclosure.

[0046] Figure 5 Schematic diagram of the detection and compensation device for the irradiation damage effect of a silicon photomultiplier tube according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. Like reference numerals in the drawings denote functionally identical or similar elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0048] In the description of the present disclosure, it should be understood that the orientation or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present disclosure.

[0049] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present disclosure, "a plurality" means two or more unless otherwise specifically defined.

[0050] In the present disclosure, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0051] The term "exemplary" used herein means "serving as an example, embodiment, or illustration". Any embodiment described as "exemplary" herein need not be construed as superior to or better than other embodiments.

[0052] The term "and / or" herein merely describes an association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality. For example, including at least one of A, B, and C may represent including any one or more elements selected from the set composed of A, B, and C.

[0053] In addition, to better illustrate the present disclosure, numerous specific details are given in the following detailed embodiments. Those skilled in the art should understand that the present disclosure can also be implemented without certain specific details. In some instances, methods, means, elements, and circuits well-known to those skilled in the art are not described in detail so as to highlight the gist of the present disclosure.

[0054] The related art mainly evaluates the irradiation damage effect of SiPM by measuring the dark count rate of SiPM or measuring the dark current using tools such as a multimeter.

[0055] Please refer to Figure 2 、 Figure 3 , Figure 2 which shows a schematic diagram of a SiPM irradiation damage effect detection device based on dark count rate measurement in the related art. Figure 3 which shows a schematic diagram of a SiPM radiation damage effect detection device based on a multimeter or ammeter in the related art.

[0056] As Figure 2 shown, the related art can evaluate the irradiation damage effect of SiPM by measuring the dark count rate of SiPM [S. Mianowski et al 2020 JINST 15 P03002]. Among them, a high-speed charge amplifier amplifies the signal output by SiPM. In a constant fraction discriminator, a suitable trigger threshold is set so that the system can be triggered by the dark count signals of single photons and multi-photons generated by SiPM. Then, by counting the count rate within a fixed time through a counter, the measurement of the dark count rate can be achieved.

[0057] As Figure 3 shown, the related art uses a multimeter or ammeter in series with SiPM to measure the dark current of SiPM. Among them, a bench-top high-voltage power supply is used to adjust and monitor the output bias voltage; a multimeter or ammeter is used in series with SiPM to measure and read the value of the dark current passing through SiPM. This method is mainly used to solve the situation where the SiPM used has a large area, a high dark count rate, the dark count signals are stacked, it is difficult to distinguish them one by one, and the dark count rate cannot be measured. The irradiation damage effect of SiPM is evaluated by measuring the dark current. And it is mainly used to detect and study the irradiation damage effect of SiPM in the laboratory.

[0058] In addition, in related technologies, there is also a method of measuring the dark current of SiPM using a power supply chip with a current mirror function. For example, some SiPM power supply chips themselves provide the function of measuring their supply current. Based on these chips, a miniaturized detection method for the irradiation damage effect of SiPM can be realized. These power supply chips can copy 20% of the SiPM supply current through a current mirror and lead it out through pins. Connect a resistor to this pin, and by measuring the voltage drop across this resistor, the measurement of the SiPM supply current can be achieved.

[0059] However, all related technologies have defects. Among them, for the existing first SiPM irradiation damage effect detection method (by measuring the dark count rate of SiPM), it is not applicable to the detection of the irradiation damage effect of large-area SiPM. In a large number of application scenarios, the area of SiPM will exceed 10mm 2 , and at room temperature, the dark count rate of SiPM will be greater than 1 MHz. At this time, the dark count signals of SiPM will be severely stacked, and the dark count rate cannot be measured.

[0060] For the existing second SiPM irradiation damage effect detection method (using a multimeter or ammeter in series with SiPM to measure the dark current of SiPM), the equipment such as the bench power supply, multimeter, and ammeter used are often bulky and have a large volume (exceeding 20×20×10 cm 3 ), and manual participation is required to read the SiPM dark current data. For the application of SiPM in high-energy physics experiments and space astrophysics experiments, it is required to be able to automatically read the SiPM dark current data in a compact space (less than 10×10×5 cm 3 ).

[0061] For the existing third SiPM irradiation damage effect detection method (using a power supply chip with a current mirror function to measure the dark current of SiPM), the total supply current of all SiPMs is measured at the power supply end, and independent detection of each channel of the separately read SiPM cannot be achieved. If a separate power supply is designed for each channel, the design cost and hardware cost will be greatly increased.

[0062] In addition, in all of the above SiPM irradiation damage effect detection methods, there is no method to compensate for the change in the bias voltage at both ends of SiPM caused by the change in the dark current of SiPM due to the irradiation damage effect. Moreover, there is also a lack of methods for detecting, evaluating, and compensating for the change in SiPM noise caused by the irradiation damage effect.

[0063] An embodiment of the present disclosure provides a detection and compensation device for the irradiation damage effect of a silicon photomultiplier tube. The device includes a power supply module, a filtering module, a current limiting resistor module, a first capacitor, a silicon photomultiplier tube, a voltage adjustment module, and / or a signal acquisition module. By collecting the voltage difference across the filtering module or the voltage difference across the current limiting resistor module through the voltage adjustment module, the dark current of the silicon photomultiplier tube is obtained. When the bias voltage across the silicon photomultiplier tube deviates from the target bias voltage by a preset range, the output voltage of the power supply module is adjusted so that the bias voltage across the silicon photomultiplier tube is within the preset range of the target bias voltage, thereby realizing the detection of the dark current of the silicon photomultiplier tube and the compensation of the bias voltage across the SiPM. The signal acquisition module is used to measure the dark count noise of the silicon photomultiplier tube, and the signal acquisition trigger threshold of the signal acquisition module is adaptively adjusted according to the measured noise, so that the signal acquisition module performs signal acquisition when the amplitude of the signal transmitted from the first capacitor is greater than or equal to the signal acquisition trigger threshold, reducing the probability of noise mis-triggering.

[0064] The detection and compensation device for the irradiation damage effect of the silicon photomultiplier tube according to the embodiment of the present disclosure can meet the measurement requirements of the dark current and noise of multi-channel and large-area SiPMs in a compact space, as well as the requirements for compensating the bias voltage across the SiPM and the change of SiPM noise.

[0065] Please refer to Figure 4 , Figure 4 which shows a schematic diagram of a detection and compensation device for the irradiation damage effect of a silicon photomultiplier tube according to an embodiment of the present disclosure.

[0066] As Figure 4 shown, the device includes a power supply module 10, a filtering module 20, a current limiting resistor module 30, a first capacitor C1, a silicon photomultiplier tube 60, a voltage adjustment module 40, and / or a signal acquisition module 50. Among them,

[0067] The power supply module 10 includes at least one voltage output terminal. The voltage output terminal is connected to the cathode of the silicon photomultiplier tube 60 through the filtering module 20, and the anode of the silicon photomultiplier tube 60 is grounded through the current limiting resistor module 30.

[0068] The voltage adjustment module 40 is connected to at least one of the common node of the silicon photomultiplier 60 and the filtering module 20, the common node of the silicon photomultiplier 60 and the current limiting resistor module 30, and the common node of the voltage output terminal and the filtering module 20. The voltage adjustment module 40 is configured to collect the voltage difference across the filtering module 20 or the voltage difference across the current limiting resistor module 30 to obtain the dark current of the silicon photomultiplier 60, and adjust the output voltage of the power supply module 10 when the bias voltage across the silicon photomultiplier 60 deviates from the target bias voltage by a preset range, so that the bias voltage across the silicon photomultiplier 60 is within the preset range of the target bias voltage;

[0069] The signal acquisition module 50 is connected to the anode of the silicon photomultiplier 60 through the first capacitor C1, configured to measure the noise of the silicon photomultiplier 60, adaptively adjust the signal acquisition trigger threshold of the signal acquisition module 50 according to the measured noise, and the signal acquisition module 50 is further configured to perform signal acquisition when the amplitude of the signal transmitted from the first capacitor C1 is greater than or equal to the signal acquisition trigger threshold.

[0070] The embodiments of the present disclosure do not limit the specific implementation manners of the power supply module 10, the filtering module 20, the current limiting resistor module 30, the voltage adjustment module 40, and the signal acquisition module 50. Those skilled in the art can adopt appropriate implementation manners according to the actual situation and needs. Exemplarily, the power supply module 10 may include a power control port and at least one voltage output terminal, and each voltage output terminal can be used to supply power to the silicon photomultiplier 60. The power supply module 10 may include an AC / DC converter and a DC / DC converter, and can be connected to the mains (alternating current) and convert it into the required direct current to supply power to the silicon photomultiplier 60; it may also include an energy storage component, such as a battery component (lithium ion battery, lithium polymer battery, etc.), and perform DC / DC conversion on the electrical energy in the battery to supply power to the silicon photomultiplier 60. Exemplarily, the filtering module 20 may include a combination of multiple resistors and capacitors to implement the filtering function, and may include a grounding capacitor. Exemplarily, the equivalent resistance of the filtering module 20 may be the resistance value measured in advance at both ends. Exemplarily, the current limiting resistor module 30 may include one or more resistors (when there are multiple resistors, they may be combined in series and parallel forms).

[0071] In a possible implementation, collecting the voltage difference across the two ends of the filtering module 20 or the voltage difference across the two ends of the current limiting resistor module 30 to obtain the dark current of the silicon photomultiplier 60 may include: determining the dark current of the silicon photomultiplier 60 according to the voltage difference across the two ends of the filtering module 20 and the equivalent resistance of the filtering module 20; or determining the dark current of the silicon photomultiplier 60 according to the anode voltage and the resistance of the current limiting resistor module 30; Exemplarily, if the measured voltage difference V across the two ends of the current limiting resistor module 30 a is obtained, then the dark current I of the silicon photomultiplier 60 dark = V a / R, where R is the resistance value of the current limiting resistor module 30.

[0072] In a possible implementation, the voltage adjustment module 40 may further be configured to:

[0073] Determine the voltage drop of the filtering module 20 according to the dark current and the equivalent resistance of the filtering module 20;

[0074] Determine the bias voltage across the two ends of the silicon photomultiplier 60 according to the output voltage of the power supply module 10, the voltage drop of the filtering module 20, and the voltage difference across the two ends of the current limiting resistor module 30.

[0075] Of course, if the voltage difference across the two ends of the filtering module 20 is directly collected, the dark current can also be calculated, the voltage drop of the current limiting resistor module 30 can be calculated, and further the bias voltage across the two ends of the silicon photomultiplier 60 can be obtained. In this regard, the embodiments of the present disclosure do not make any limitations.

[0076] Exemplarily, if the measured voltage at the power supply terminal of the silicon photomultiplier 60 ( Figure 4 in is the voltage of the common node of the voltage output terminals of the filtering module 20, the voltage adjustment module 40, and the power supply module 10), that is, the output voltage V of the power supply module 10 apply is obtained, combined with the measured dark current value I dark , it can be known that the voltage drop V drop across the filtering module 20 is I dark ×R f , where R f is the equivalent resistance of the filtering module 20. At this time, the bias voltage across the two ends of the silicon photomultiplier 60 is equal to V apply -I dark ×R f -V a .

[0077] The embodiments of the present disclosure do not make any limitations on the specific manner of adjusting the output voltage of the power supply module 10. Exemplarily, a PID control (Proportional-Integral-Derivative control) method can be used to adjust the output voltage.

[0078] Please refer to Figure 5 , Figure 5 which shows a schematic diagram of a detection and compensation device for the radiation damage effect of a silicon photomultiplier according to an embodiment of the present disclosure.

[0079] In a possible implementation, as Figure 5 shown, the voltage adjustment module 40 may include a first control unit 400, a first voltage acquisition unit 410, a second voltage acquisition unit 420, and a third voltage acquisition unit 430. The first voltage acquisition unit 410, the second voltage acquisition unit 420, and the third voltage acquisition unit 430 may each include a voltage follower and an analog-to-digital converter. Among them,

[0080] the input end of the first voltage acquisition unit 410 is connected to the common node of the voltage output end and the filtering module 20, and the output end of the first voltage acquisition unit 410 is connected to the first input end of the first control unit 400.

[0081] the input end of the second voltage acquisition unit 420 is connected to the anode of the silicon photomultiplier 60 and the first end of the current limiting resistance module 30 (the common node of the silicon photomultiplier and the current limiting resistance module), and the output end of the second voltage acquisition unit 420 is connected to the second input end of the first control unit 400.

[0082] the input end of the third voltage acquisition unit 430 is connected to the common node of the silicon photomultiplier 60 and the filtering module 20, and the output end of the third voltage acquisition unit 430 is connected to the third input end of the first control unit 400.

[0083] the output end of the first control unit 400 is connected to the power supply module 10 and is used to perform at least one of the following:

[0084] obtain the dark current according to the voltage difference across the current limiting resistance module 30 collected by the second voltage acquisition unit 420 and the resistance of the current limiting resistance module 30;

[0085] obtain the dark current of the silicon photomultiplier 60 according to the voltage of the common node of the silicon photomultiplier 60 and the filtering module 20 collected by the third voltage acquisition unit 430, the output voltage of the power supply module 10 collected by the first voltage acquisition unit 410, and the equivalent resistance of the filtering module 20;

[0086] determine the voltage drop of the filtering module 20 according to the dark current and the equivalent resistance of the filtering module 20;

[0087] Determine the bias voltage across the silicon photomultiplier 60 based on the output voltage of the power supply module 10, the voltage drop across the filtering module 20, and the voltage difference across the current limiting resistor module 30 collected by the first voltage acquisition unit 410. When the bias voltage across the silicon photomultiplier 60 deviates from the target bias voltage by a preset range, adjust the output voltage of the power supply module 10 so that the bias voltage across the silicon photomultiplier 60 is within the preset range of the target bias voltage.

[0088] Of course, those skilled in the art can also modify the above voltage adjustment module. For example, only one or two voltage acquisition units can be used. Taking two as an example, a switch unit can be added to connect to the common node of the silicon photomultiplier 60 and the filtering module 20, and the common node of the silicon photomultiplier 60 and the current limiting resistor module 30, and the switch unit can be used to control the connection of the two voltage acquisition units to at least one of the common node of the silicon photomultiplier 60 and the filtering module 20, the common node of the silicon photomultiplier 60 and the current limiting resistor module 30, and the common node of the voltage output terminal and the filtering module 20. In this regard, the embodiments of the present disclosure do not make any limitations.

[0089] In a possible implementation manner, the first control unit 400 can be implemented by a processing component. In one example, the processing component includes, but is not limited to, a separate processor, or discrete components, or a combination of a processor and discrete components. The processor can include a controller in an electronic device having an instruction execution function, and the processor can be implemented in any suitable manner. For example, it can be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components. Inside the processor, the executable instructions can be executed through hardware circuits such as logic gates, switches, application specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers.

[0090] In one example, the first voltage acquisition unit 410 includes a first voltage follower VF1 and a first analog-to-digital converter ADC1. The input end of the first voltage follower VF1 is connected to the common node of the filtering module 20 and the voltage output terminal, and the first voltage follower VF1 is connected to the first control unit 400 through the first analog-to-digital converter ADC1.

[0091] In one example, the second voltage acquisition unit 420 includes a second voltage follower VF2 and a second analog-to-digital converter ADC2. The input end of the second voltage follower VF2 is connected between the current limiting resistor module 30 and the silicon photomultiplier 60, and the second voltage follower VF2 is connected to the first control unit 400 through the second analog-to-digital converter ADC2.

[0092] In one example, the third voltage acquisition unit 430 includes a third voltage follower VF3 and a third analog-to-digital converter ADC3. The input end of the third voltage follower VF3 is connected to the common node of the filtering module 20 and the silicon photomultiplier 60, and the third voltage follower VF3 is connected to the first control unit 400 through the third analog-to-digital converter ADC3.

[0093] The embodiments of the present disclosure do not limit the specific implementation manners of the voltage follower and the analog-to-digital converter, and those skilled in the art can adopt relevant technologies to implement them.

[0094] In the embodiments of the present disclosure, when a power supply module 10 supplies power to multiple channels of SiPMs, the measurement of the dark current and the bias voltage compensation of the corresponding SiPM channel connected to a certain channel can be realized.

[0095] In a possible implementation manner, measuring the noise of the silicon photomultiplier 60 and adaptively adjusting the signal acquisition trigger threshold of the signal acquisition module 50 according to the measured noise, and performing signal acquisition when the amplitude of the signal transmitted from the first capacitor C1 is greater than or equal to the signal acquisition trigger threshold may include:

[0096] Disconnect the power supply to the silicon photomultiplier 60, input a test signal at the second end of the first capacitor C1 to obtain the electronic noise of the signal acquisition module 50;

[0097] Restore the power supply to the silicon photomultiplier 60, input a test signal at the second end of the first capacitor C1 to obtain the overall noise, where the overall noise includes the electronic noise and the dark count noise of the silicon photomultiplier 60;

[0098] Determine the dark count noise of the silicon photomultiplier 60 according to the overall noise and the electronic noise;

[0099] Set the acquisition trigger threshold of the signal acquisition module 50 to a preset multiple of the overall noise, where the preset multiple is greater than 3.

[0100] In an embodiment of the present disclosure, the power supply to the silicon photomultiplier 60 is disconnected, a test signal is input to the second end of the first capacitor C1, and the electronic noise of the signal acquisition module 50 is obtained; the power supply to the silicon photomultiplier 60 is restored, a test signal is input to the second end of the first capacitor C1, and the overall noise is obtained, where the overall noise includes the electronic noise and the dark count noise of the silicon photomultiplier 60; the dark count noise of the silicon photomultiplier 60 is determined according to the overall noise and the electronic noise, and the acquisition trigger threshold of the signal acquisition module 50 is set to a preset multiple of the overall noise, so as to measure the dark count noise of the silicon photomultiplier 60, and adaptively adjust the signal acquisition trigger threshold of the signal acquisition module 50 according to the measured overall noise.

[0101] In a possible implementation manner, the preset multiple in the embodiment of the present disclosure is 6.

[0102] In a possible implementation manner, as Figure 5 shown, the signal acquisition module 50 includes a second control unit 510, a switch unit 520, a second capacitor C2, a signal processing unit 530, a digital-to-analog conversion unit 550, a trigger 540, and an acquisition unit 560, where

[0103] The first output end of the second control unit 510 is connected to the second end of the first capacitor C1 and the input end of the signal processing unit 530 through the switch unit 520 and the second capacitor C2,

[0104] The second output end of the second control unit 510 is connected to the trigger 540 through the digital-to-analog conversion unit 550,

[0105] The output end of the signal processing unit 530 is connected to the input end of the trigger 540 and the input end of the acquisition unit 560,

[0106] The control end of the acquisition unit 560 is connected to the output end of the trigger 540, and the output end of the acquisition unit 560 is connected to the input end of the second control unit 510,

[0107] Among them, the second control unit 510 is used to output a switch control signal to control the conduction state of the switch unit 520 to change, so that the voltage across the second capacitor C2 changes, thereby inputting the test signal to the input end of the signal processing unit 530. Among them, in Figure 5In the illustrated embodiment, the input end of the signal processing unit 530 is connected to the second end of the first capacitor C1. The test signal can be a square wave generated by the on and off of a switch, or other forms of test signals generated by other means, such as narrow pulse signals, etc.

[0108] The signal processing unit 530 is configured to perform voltage conversion on the received signal and output an intermediate voltage signal.

[0109] The trigger 540 is configured to trigger the acquisition unit 560 to acquire a signal (i.e., the intermediate voltage signal output by the signal processing unit 530) when the voltage amplitude of the intermediate voltage signal is greater than or equal to the acquisition trigger threshold of the trigger 540, wherein the acquisition trigger threshold of the trigger 540 is set by the second control unit 510 through the digital-to-analog conversion unit 550.

[0110] The acquisition unit 560 is configured to perform analog-to-digital conversion on the acquired intermediate voltage signal and output it to the second control unit 510.

[0111] In one example, the second control unit 510 may be the aforementioned processing component.

[0112] In a possible implementation manner, the switch unit 520 includes an analog switch, the signal processing unit 530 includes a multi-stage amplification circuit, and the acquisition unit 560 includes a peak hold circuit and an analog-to-digital converter. Exemplarily, the first-stage preamplifier of the multi-stage amplification circuit can be a transimpedance amplifier for converting a charge signal or a current signal into a voltage signal; the second stage is a main amplifier for performing functions such as signal polarity inversion, low-pass filtering, and amplitude amplification. Exemplarily, the peak hold circuit is used to hold the peak of the input voltage pulse signal to form a constant voltage value output for conversion by the analog-to-digital converter. In one example, the second control unit 510 controls the analog switch to switch between on and off, causing the voltage across the second capacitor C2 to change, thereby injecting a fixed amount of charge (test signal) into the input end of the signal processing unit 530. The signal processing unit 530 will convert this charge pulse into a voltage signal and output it. On the one hand, it is supplied to the acquisition unit 560 for acquisition, and on the other hand, it is input to the trigger 540. When the voltage amplitude exceeds the acquisition trigger threshold generated by the digital-to-analog conversion unit 550, a trigger signal is generated to inform the acquisition unit 560 to start acquisition. The analog-to-digital converter of the acquisition unit 560 converts the voltage value into a digital quantity, which is read and saved by the second control unit 510 for data analysis.

[0113] Exemplarily, before each use of the silicon photomultiplier 60, the power supply to the silicon photomultiplier 60 can be disconnected (for example, the power module 10 does not output voltage to the common node of the voltage adjustment module and the filtering module 20), and a test signal is input to the second end of the first capacitor C1 through the switch unit 520 and the second capacitor C2 in the signal acquisition module 50 to obtain the electronic noise of the signal acquisition module 50. Exemplarily, the noise can be represented by the signal amplitude broadening of the signal collected by the acquisition unit 560, and the signal amplitude broadening can be obtained by processing the signal collected by the acquisition unit 560 through the second control unit 510. For example, the signal amplitude broadening σ ele Is only contributed by the electronic noise of the electronics system; wherein, the definition of the signal amplitude broadening is the standard deviation of the statistical distribution of the signal amplitude. Exemplarily, it is to make a statistical distribution histogram of the signal amplitude, perform Gaussian distribution fitting on it, and obtain the standard deviation.

[0114] Exemplarily, after obtaining the electronic noise, the power supply to the silicon photomultiplier 60 is restored, a test signal is input to the second end of the first capacitor C1, and in a similar manner as above, through the acquisition of the acquisition unit 560 and the processing of the second control unit 510, the overall noise is obtained, and the signal amplitude broadening σ total Is used to represent that the overall noise includes the electronic noise and the dark count noise σ SiPM ;

[0115] Exemplarily, the dark count noise of the silicon photomultiplier 60 is determined according to the overall noise and the electronic noise. For example, it can be determined by the following formula:

[0116] Exemplarily, the acquisition trigger threshold of the signal acquisition module 50 is set to a preset multiple of the overall noise. For example, the acquisition trigger threshold is adjusted to 6×σ total .

[0117] Thereafter, the second control unit 510 no longer controls the switch unit 520 to conduct and turn off, that is, no test signal is generated anymore. The output signal at the second end of the first capacitor C1 is provided to the trigger 540 and the acquisition unit 560 through the signal processing unit 530. When the output signal reaches the set acquisition trigger threshold 6×σ total After that, the trigger 540 triggers the acquisition unit 560 to acquire the output signal.

[0118] For the method of measuring the dark current of the silicon photomultiplier, compared with the related art, the device for measuring the dark current in the embodiments of the present disclosure is greatly simplified, facilitating integration and miniaturization, and can measure the dark current of different silicon photomultiplier channels under the power supply of a single power source. Moreover, the embodiments of the present disclosure can perform adaptive compensation for the voltage drop of the silicon photomultiplier, can avoid the change of the bias voltage at both ends of the silicon photomultiplier caused by irradiation damage, and can improve the gain stability of the silicon photomultiplier. Furthermore, it can avoid the continuous triggering of the readout electronics noise by the noise, which affects the readout and acquisition of normal signals.

[0119] The embodiments of the present disclosure have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, the practical application, or the improvement of the technology in the market, or to enable other ordinary skilled persons in the technical field to understand the embodiments disclosed herein.

Claims

1. A detection and compensation device for the irradiation damage effect of a silicon photomultiplier tube, characterized in that The device includes a power supply module, a filtering module, a current-limiting resistor module, a first capacitor, a silicon photomultiplier tube, a voltage adjustment module and / or a signal acquisition module, wherein, The power supply module includes at least one voltage output terminal. The voltage output terminal is connected to the cathode of the silicon photomultiplier tube through the filtering module, and the anode of the silicon photomultiplier tube is grounded through the current-limiting resistor module. The voltage adjustment module is connected to at least one of the common node of the silicon photomultiplier tube and the filtering module, the common node of the silicon photomultiplier tube and the current-limiting resistor module, and the common node of the voltage output terminal and the filtering module. The voltage adjustment module is used to collect the voltage difference across the filtering module or the voltage difference across the current-limiting resistor module to obtain the dark current of the silicon photomultiplier tube, and when the bias voltage across the silicon photomultiplier tube deviates from the target bias voltage by a preset range, adjust the output voltage of the power supply module so that the bias voltage across the silicon photomultiplier tube is within the preset range of the target bias voltage. The signal acquisition module is connected to the anode of the silicon photomultiplier tube through the first capacitor, and is used to measure the dark count noise of the silicon photomultiplier tube and adaptively adjust the signal acquisition trigger threshold of the signal acquisition module according to the measured noise. The signal acquisition module is also used to perform signal acquisition when the amplitude of the signal transmitted from the first capacitor is greater than or equal to the signal acquisition trigger threshold. Collecting the voltage difference across the filtering module or the voltage difference across the current-limiting resistor module to obtain the dark current of the silicon photomultiplier tube includes: determining the dark current of the silicon photomultiplier tube according to the voltage difference across the filtering module and the equivalent resistance of the filtering module; or determining the dark current of the silicon photomultiplier tube according to the voltage difference across the current-limiting resistor module and the resistance of the current-limiting resistor module. The voltage adjustment module is further used to: Determine the voltage drop of the filtering module according to the dark current and the equivalent resistance of the filtering module; Determine the bias voltage across the silicon photomultiplier tube according to the output voltage of the power supply module, the voltage difference across the filtering module and the voltage difference across the current-limiting resistor module.

2. The device according to claim 1, characterized in that The voltage adjustment module includes a first control unit, a first voltage acquisition unit, a second voltage acquisition unit, and a third voltage acquisition unit. The first voltage acquisition unit, the second voltage acquisition unit, and the third voltage acquisition unit all include a voltage follower and an analog-to-digital converter, wherein, The input terminal of the first voltage acquisition unit is connected to the common node of the voltage output terminal and the filtering module, and the output terminal of the first voltage acquisition unit is connected to the first input terminal of the first control unit. The input terminal of the second voltage acquisition unit is connected to the common node of the silicon photomultiplier tube and the current-limiting resistor module, and the output terminal of the second voltage acquisition unit is connected to the second input terminal of the first control unit. The input end of the third voltage acquisition unit is connected to the common node of the silicon photomultiplier tube and the filtering module, and the output end of the third voltage acquisition unit is connected to the third input end of the first control unit. The output end of the first control unit is connected to the power supply module and is used to perform at least one of the following: Obtain the dark current according to the voltage difference across the current-limiting resistance module acquired by the second voltage acquisition unit and the resistance of the current-limiting resistance module; Determine the dark current of the silicon photomultiplier tube according to the voltage of the common node of the silicon photomultiplier tube and the filtering module acquired by the third voltage acquisition unit, the output voltage of the power supply module acquired by the first voltage acquisition unit, and the equivalent resistance of the filtering module; Determine the voltage drop of the filtering module according to the dark current and the equivalent resistance of the filtering module; Determine the bias voltage across the silicon photomultiplier tube according to the output voltage of the power supply module acquired by the first voltage acquisition unit, the voltage drop of the filtering module, and the voltage difference across the current-limiting resistance module, and adjust the output voltage of the power supply module when the bias voltage across the silicon photomultiplier tube deviates from the target bias voltage by a preset range, so that the bias voltage across the silicon photomultiplier tube is within the preset range of the target bias voltage.

3. The device according to claim 1, characterized in that, Measuring the dark count noise of the silicon photomultiplier tube and adaptively adjusting the signal acquisition trigger threshold of the signal acquisition module according to the measured noise, and performing signal acquisition when the amplitude of the signal transmitted from the first capacitor is greater than or equal to the signal acquisition trigger threshold, includes: Disconnect the power supply to the silicon photomultiplier tube, input a test signal at the second end of the first capacitor to obtain the electronic noise of the signal acquisition module; Restore the power supply to the silicon photomultiplier tube, input a test signal at the second end of the first capacitor to obtain the overall noise, where the overall noise includes the electronic noise and the dark count noise of the silicon photomultiplier tube; Determine the dark count noise of the silicon photomultiplier tube according to the overall noise and the electronic noise; Set the acquisition trigger threshold of the signal acquisition module to a preset multiple of the overall noise, where the preset multiple is greater than 3.

4. The device according to claim 3, characterized in that, The preset multiple is 6.

5. The device according to claim 3, characterized in that, The signal acquisition module includes a second control unit, a switch unit, a second capacitor, a signal processing unit, a digital-to-analog conversion unit, a trigger, and an acquisition unit, where The first output end of the second control unit is connected to the second end of the first capacitor and the input end of the signal processing unit through the switch unit and the second capacitor; The second output end of the second control unit is connected to the trigger through the digital-to-analog conversion unit; The output end of the signal processing unit is connected to the input end of the trigger and the input end of the acquisition unit; The control end of the acquisition unit is connected to the output end of the trigger, and the output end of the acquisition unit is connected to the input end of the second control unit. Among them, the second control unit is used to output a switch control signal to control the on-state of the switch unit to change, so that the voltage across the second capacitor changes, thereby inputting the test signal to the input end of the signal processing unit. The signal processing unit is used to perform voltage conversion on the received signal and output an intermediate voltage signal. The trigger is used to trigger the acquisition unit to acquire a signal when the voltage amplitude of the intermediate voltage signal is greater than or equal to the acquisition trigger threshold of the trigger. Among them, the acquisition trigger threshold of the trigger is set by the second control unit through the digital-to-analog conversion unit. The acquisition unit is used to perform analog-to-digital conversion on the acquired intermediate voltage signal and output it to the second control unit.

6. The device according to claim 5, characterized in that, The switch unit includes an analog switch, the signal processing unit includes a multi-stage amplifier circuit, and the acquisition unit includes a peak hold circuit and an analog-to-digital converter.

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