Testing device and method for pulse saturation recovery characteristics of micro-channel plate photomultiplier tube

Abstract

The present application relates to photomultiplier tube testing device and method, specifically relates to a kind of microchannel plate type photomultiplier tube pulse saturation recovery characteristic testing device and method, solve the technical problems that existing MCP-PMT pulse saturation recovery characteristic testing device does not match with actual application demand, cannot evaluate the pulse saturation recovery characteristic under different saturation depth and different recovery degree.The present application utilizes laser diode and light attenuator in dark box environment, and pulse signal generator, power divider, combiner, high voltage source, digitizer and data processing unit carry out pulse saturation recovery characteristic test to MCP-PMT, pulse signal generator generates two drive pulse signals with different pulse width in succession, and it matches with the actual application demand that MCP-PMT works in linear state, measurement result can reflect the saturation recovery characteristic of MCP-PMT in actual application, also can evaluate the pulse saturation recovery characteristic of MCP-PMT under different saturation depth and different recovery degree.

Description

TECHNICAL FIELD

[0001] The application relates to a photomultiplier tube testing device and method, in particular to a microchannel plate photomultiplier tube pulse saturation recovery characteristic testing device and method. BACKGROUND

[0002] The photomultiplier tube is a kind of photoelectric detection device which can convert extremely weak optical signals into electrical signals and amplify them. The microchannel plate photomultiplier tube (MCP-PMT for short) is a kind of photomultiplier tube, uses a microchannel plate (MCP for short) as an electron multiplication component, and has the characteristics of small size, fast time response and high time resolution, and is mainly used for measuring sub-nanosecond to nanosecond ultrafast time histories.

[0003] The MCP is a plate-shaped structure composed of millions of microchannels with a diameter of several microns to tens of microns. The inner surface of each channel is covered with a secondary electron emission material. When the photoelectron emitted by the photocathode enters the microchannel, it will accelerate through the microchannel under the action of the electric field and collide with the inner wall of the microchannel to generate secondary electrons. Each collision will increase the number of electrons, thereby realizing the amplification of the electronic signal. When the pulse light incident on the photocathode is strong, the number of electrons incident on the microchannel is also large, and the number of secondary electrons emitted by the emission layer on the inner wall of the microchannel is also large. On the one hand, a large number of multiplied electrons will accumulate at the end of the microchannel, forming a local electric field different from the electric field in the microchannel, which inhibits the multiplication of subsequent electrons; on the other hand, the resistance of the MCP is very high, and the conductive layer on the inner wall of the microchannel cannot supply electrons to the secondary electron emission layer in time. At this time, the electron flow output by the MCP-PMT no longer increases linearly with the increase of the input light intensity, and enters a so-called nonlinear state or saturation state.

[0004] The MCP-PMT needs a certain time to recover from the saturation state to the linear state, i.e. the saturation recovery time. If pulse light is incident on the photocathode within the saturation recovery time, the output of the photomultiplier tube will still not be linearly related to the incident light intensity, resulting in a large measurement error, and even an incorrect measurement result. Therefore, it is crucial to accurately measure the pulse saturation recovery characteristics of the MCP-PMT. The existing MCP-PMT pulse saturation recovery characteristic testing device uses two beams of pulse light with the same width and intensity to sequentially incident on the MCP-PMT, both beams of light make the MCP-PMT work in the saturation state, but the second beam of pulse light also makes the MCP-PMT saturated, which does not meet the actual application requirements of the MCP-PMT working in the linear state, and the measurement result cannot reflect the saturation recovery characteristics of the MCP-PMT in actual application. In addition, the existing testing device cannot evaluate the pulse saturation recovery characteristics of the MCP-PMT under different saturation depths and different recovery degrees. SUMMARY

[0005] The present application aims at solving the technical problem that the existing MCP-PMT pulse saturation recovery characteristic testing device cannot meet the actual application requirements and cannot evaluate the pulse saturation recovery characteristics under different saturation depths and different recovery degrees, and provides a micro-channel plate photomultiplier tube pulse saturation recovery characteristic testing device and method.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A micro-channel plate photomultiplier tube pulse saturation recovery characteristic testing device, characterized in that it comprises a dark box, a laser diode, a light attenuating sheet and a phototube arranged in the dark box, and a pulse signal generator, a power divider, a combiner, a high voltage source, a digitizer and a data processing unit.

[0008] The first output channel of the pulse signal generator is connected with one input end of the combiner, the second output channel is connected with the input end of the power divider, one output end of the power divider is connected with the other input end of the combiner, the other output end is connected with the trigger end of the digitizer, and the output end of the combiner is connected with the driving end of the laser diode.

[0009] The first output channel and the second output channel of the pulse signal generator have a continuously adjustable output delay, and the pulse width of the driving pulse output by the first output channel is greater than that of the second output channel; the pulse signal generator is used for driving the laser diode to generate a pulse light signal and triggering the digitizer; the combiner is used for combining the driving pulse output by the first output channel of the pulse signal generator and the driving pulse output by one output end of the power divider into one road, so as to drive the laser diode to generate two pulse light signals in one output period.

[0010] The phototube is arranged at the rear end of the laser diode, the side of which is arranged with the to-be-tested MCP-PMT, and the light attenuating sheet is arranged at the front end of the to-be-tested MCP-PMT; the phototube is used for monitoring the light intensity change of the laser diode, and the light attenuating sheet is used for attenuating the light intensity incident to the to-be-tested MCP-PMT.

[0011] The light cathode incident window of the to-be-tested MCP-PMT and the phototube are both located in the light range of the laser diode, the high voltage input ends are respectively connected with the output ends of the high voltage source, the anode output ends are respectively connected with two input channels of the digitizer, and the output end of the digitizer is connected with the data processing unit.

[0012] Further, the distance between the laser diode and the to-be-tested MCP-PMT and the phototube is 20 cm.

[0013] Further, the light attenuating sheet adopts a reflective neutral density light attenuating sheet.

[0014] The digitizer adopts an oscilloscope or a plug-in digital processor.

[0015] Further, the dark box is an iron cabinet body with inside spraying of matt black paint.

[0016] The application further provides a method for testing the pulse saturation recovery characteristics of a micro-channel plate photomultiplier tube, which adopts the micro-channel plate photomultiplier tube pulse saturation recovery characteristic testing device, and has the following steps:

[0017] Step 1, turn on the digitizer and the high-voltage source, set the amplitude, frequency and pulse width of the driving pulse output by the first output channel of the pulse signal generator, the time interval and variation range of the amplitude, frequency and pulse width of the driving pulse output by the second output channel, and the range and time interval of the output delay variation between the first output channel and the second output channel of the pulse signal generator;

[0018] Step 2, turn on the pulse signal generator, and make the second output channel output the driving pulse according to the set time interval and variation range of the amplitude, frequency and pulse width, and the power divider divides the driving pulse output by the second output channel into two paths, one of which is sent to the laser diode through the combiner to drive the laser diode to generate a pulse light signal, and the other is sent to the digitizer to trigger the digitizer to start working;

[0019] Step 3, the pulse light signal is attenuated by the light attenuation sheet and then enters the to-be-tested MCP-PMT, and the pulse light signal directly enters the phototube, and the to-be-tested MCP-PMT and the phototube generate a light response signal after receiving the pulse light signal and send the light response signal to the digitizer, and the digitizer converts the light response signal into a digital signal and sends the digital signal to the data processing unit to obtain the output signals of the to-be-tested MCP-PMT and the phototube;

[0020] Step 4, the data processing unit processes the output signals of the to-be-tested MCP-PMT and the phototube, calculates the output charge of the to-be-tested MCP-PMT and the phototube under different pulse width driving pulses, and further obtains the working curve of the to-be-tested MCP-PMT;

[0021] Step 5, set the pulse width of the driving pulse output by the second output channel of the pulse signal generator to a fixed pulse width which is smaller than the pulse width of the driving pulse output by the first output channel, and then make the first output channel and the second output channel output the driving pulse according to the set amplitude, frequency and pulse width, and the range and time interval of the output delay variation;

[0022] Step 6, the power divider divides the driving pulse output by the second output channel into two paths, one of which is combined with the driving pulse output by the first output channel in the combiner to form one path, and then sent to the laser diode to drive the laser diode to generate two pulsed light signals in sequence in one output period, and the other path is sent to the digitizer to trigger the digitizer to start working, and then the output signal of the MCP-PMT to be tested under different output delays is obtained according to the method of step 3.

[0023] Step 7, the data processing unit normalizes the output signal of the MCP-PMT to be tested under different output delays according to the working curve of the MCP-PMT to be tested obtained in step 4, and further obtains the pulse saturation recovery characteristic curve of the MCP-PMT to be tested.

[0024] Further, it further comprises:

[0025] Step 8, adjust the pulse width of the driving pulse output by the first output channel of the pulse signal generator, and the pulse width of the driving pulse output by the second output channel is unchanged, and the pulse saturation recovery characteristic curve of the MCP-PMT to be tested under different saturation depths is obtained according to the method of steps 5-7.

[0026] The saturation depth is calculated by the following method:

[0027] The linear fitting value of the working curve of the MCP-PMT to be tested is obtained by linear fitting the linear region of the working curve of the MCP-PMT to be tested obtained in step 4, and then the saturation depth D of the MCP-PMT to be tested under different pulse widths is calculated according to the following formula:

[0028]

[0029] Wherein, Q 饱和 is the output charge amount of the saturation region in the working curve of the MCP-PMT to be tested, and Q 拟合 is the linear fitting value corresponding to the output charge amount of the saturation region in the working curve of the MCP-PMT to be tested.

[0030] Further, it further comprises:

[0031] Step 9, keep the pulse width of the driving pulse output by the first output channel of the pulse signal generator unchanged, adjust the pulse width of the driving pulse output by the second output channel to be less than that of the first output channel, and then the pulse saturation recovery characteristic curve of the MCP-PMT to be tested under different recovery degrees is obtained according to the method of steps 5-7.

[0032] Further, step 4 is specifically:

[0033] 4.1, calculate the output charge amount Q of the MCP-PMT to be tested and the phototube according to the following formula respectively:

[0034]

[0035] wherein, V i is the amplitude of the output signal of the MCP-PMT or phototube to be measured at the i th sampling point;

[0036] R is the input impedance of the digitizer, and f is the sampling frequency of the digitizer;

[0037] 4.2. A curve is plotted with the output charge of the phototube as the horizontal axis and the output charge of the MCP-PMT to be measured as the vertical axis to obtain the working curve of the MCP-PMT to be measured.

[0038] Further, step 7 is specifically:

[0039] 7.1. The output charge Q1 of the output signal of the MCP-PMT to be measured corresponding to the driving pulse output by the second output channel of the pulse signal generator is calculated according to the method of step 4.1.

[0040] 7.2. The output charge Q of the MCP-PMT to be measured under the driving pulse with the set pulse width of the second output channel of the pulse signal generator is obtained according to the working curve of the MCP-PMT to be measured obtained in step 4. 设定 ;

[0041] 7.3. The output of the MCP-PMT to be measured is normalized by taking Q 设定 1 as the horizontal axis and Q as the vertical axis to obtain the normalized output of the MCP-PMT to be measured.

[0042] 7.4. A curve is plotted with the output delay between the first output channel and the second output channel of the pulse signal generator as the horizontal axis and the normalized output of the MCP-PMT to be measured as the vertical axis to obtain the pulse saturation recovery characteristic curve of the MCP-PMT to be measured.

[0043] Further, in step 5, the amplitude of the driving pulse output by the first output channel of the pulse signal generator is 2V, the frequency is 1Hz, and the pulse width is 2μs, the amplitude of the driving pulse output by the second output channel of the pulse signal generator is 4V, the frequency is 1Hz, and the pulse width is 100ns, and the output delay between the first output channel and the second output channel changes in the range of 100ns-900ms.

[0044] Compared with the prior art, the present application has the beneficial technical effects as follows:

[0045] The application provides a kind of microchannel plate photomultiplier tube pulse saturation recovery characteristic testing device, utilize laser diode and light attenuating piece in dark box environment, and pulse signal generator, power divider, combiner, high voltage source, digitizer and data processing unit carry out pulse saturation recovery characteristic test to MCP-PMT, pulse signal generator generates two drive pulse signals with different pulse widths in succession, and it is consistent with the actual application requirement that MCP-PMT works in linear state, measurement result can reflect the saturation recovery characteristic of MCP-PMT in actual application, also can evaluate the pulse saturation recovery characteristic of MCP-PMT under different saturation depth and different recovery degree. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is the structural schematic diagram of testing device in the embodiment of the application;

[0047] Figure 2 It is the output signal waveform diagram of the MCP-PMT and phototube to be measured when the drive pulse width obtained in step 3 of the test method in the embodiment of the application is 85ns;

[0048] Figure 3 It is the working curve of the MCP-PMT to be measured and its linear fitting curve diagram obtained in step 4 of the test method in the embodiment of the application;

[0049] Figure 4 It is the output signal waveform diagram of the MCP-PMT and phototube to be measured when the output delay of pulse signal generator obtained in step 6 of the test method in the embodiment of the application is 1us;

[0050] Figure 5 It is the pulse saturation recovery characteristic curve diagram of the MCP-PMT to be measured obtained in step 7 of the test method in the embodiment of the application;

[0051] Figure 6 It is the pulse saturation recovery characteristic curve diagram of the MCP-PMT to be measured under different saturation depth obtained in step 8 of the test method in the embodiment of the application;

[0052] Figure 7 It is the pulse saturation recovery characteristic curve diagram of the MCP-PMT to be measured under different recovery degree obtained in step 9 of the test method in the embodiment of the application;

[0053] The reference signs are explained as follows:

[0054] 1-pulse signal generator, 2-power divider, 3-combiner, 4-dark box, 5-laser diode, 6-light attenuating piece, 7-MCP-PMT to be measured, 8-phototube, 9-high voltage source, 10-digitizer, 11-data processing unit. DETAILED DESCRIPTION

[0055] The following is a further detailed description of the device and method for testing the pulse saturation recovery characteristics of a microchannel plate photomultiplier tube (PMT) proposed in the present invention, in conjunction with the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that these embodiments are merely intended to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0056] A device for testing the pulse saturation recovery characteristics of a microchannel plate photomultiplier tube, such as Figure 1 As shown, the apparatus comprises a dark box 4, a laser diode 5, a light attenuation sheet 6, and a photoelectric tube 8 disposed therein, as well as a pulse signal generator 1, a power divider 2, a combiner 3, a high-voltage source 9, a digitizer 10, and a data processing unit 11. The dark box 4 is a closed experimental space with a black interior and cable holes in the side walls. In this embodiment, the dark box 4 is constructed as an iron cabinet with a matte black interior.

[0057] The first output channel of the pulse signal generator 1 is connected to an input end of the combiner 3, the second output channel is connected to the input end of the power divider 2, one output end of the power divider 2 is connected to another input end of the combiner 3, the other output end is connected to the trigger end of the digitizer 10, and the output end of the combiner 3 is connected to the driving end of the laser diode 5.

[0058] The output delay between the first and second output channels of pulse signal generator 1 is continuously adjustable from nanoseconds to seconds, and the pulse width of the drive pulse output by the first output channel is greater than that of the second output channel. Pulse signal generator 1 is used to drive laser diode 5 to generate a pulsed light signal and trigger digitizer 10. During testing, the drive pulse output by the first output channel can operate the MCP-PMT 7 under test in a saturated state, while the drive pulse output by the second output channel can operate the MCP-PMT 7 under test in a linear state.

[0059] In this embodiment, the first output channel of pulse signal generator 1 outputs a drive pulse with an amplitude of 2V, a pulse width of 2μs, and a frequency of 1Hz. The second output channel outputs a drive pulse with an amplitude of 4V, a pulse width of 100ns, and a frequency of 1Hz. During testing, the output delay between the first and second output channels was adjusted from 100ns to 900ms, with the drive pulse output from the second output channel being output after the drive pulse output from the first output channel.

[0060] Combiner 3 combines the drive pulses from the first output channel of pulse signal generator 1 with the drive pulses from one output port of power divider 2, thereby driving laser diode 5 to generate two pulsed optical signals within one output cycle. The duration and time interval of the pulsed optical signals are determined by the output settings of the first and second output channels of pulse signal generator 1.

[0061] The laser diode 5 is used as a test pulse light source to generate photoelectrons on the photocathode of the MCP-PMT 7 and the phototube 8. The wavelength of the laser diode is selected according to the spectral range to be tested. In this embodiment, the central wavelength of the laser diode is 405 nm. The width of the output pulse light signal is determined by the width of the driving pulse. The intensity of the output pulse light signal can be adjusted and set by the control software.

[0062] The phototube 8 is arranged at the rear end of the laser diode 5, and the MCP-PMT 7 to be tested is arranged at one side of the phototube 8. The light attenuation sheet 6 is arranged at the front end of the MCP-PMT 7 to be tested. The phototube 8 is used to monitor the light intensity change of the laser diode 5 and obtain the working curve of the MCP-PMT 7 to be tested. The light attenuation sheet 6 is a reflective neutral density filter, which is used to attenuate the light intensity incident on the MCP-PMT 7 to be tested. The photocathode incident window of the MCP-PMT 7 to be tested and the phototube 8 is located within the illumination range of the laser diode 5, and it is ensured that the light emitted by the laser diode 5 is uniformly irradiated on the photocathode incident window of the MCP-PMT 7 to be tested and the phototube 8. In this embodiment, the distance between the laser diode 5 and the MCP-PMT 7 to be tested and the phototube 8 is 20 cm.

[0063] The high-voltage input ends of the phototube 8 and the MCP-PMT 7 to be tested are respectively connected to the output ends of the high-voltage source 9, and the anode output ends are respectively connected to two input channels of the digitizer 10. The output end of the digitizer 10 is connected to the data processing unit 11. The high-voltage source 9 is used to provide DC high voltage for the MCP-PMT 7 to be tested and the phototube 8. The gain of the MCP-PMT 7 to be tested can be adjusted by adjusting the output voltage value of the high-voltage source 9. The digitizer 10 is an oscilloscope or a plug-in digital processor, which is used to convert the analog electrical signals output by the MCP-PMT 7 to be tested and the phototube 8 into digital signals.

[0064] The microchannel plate photomultiplier pulse saturation recovery characteristic testing device provided by the embodiment is used for testing the pulse saturation recovery characteristic of the to-be-tested MCP-PMT 7 in a dark box environment by using a laser diode 5, a light attenuation sheet 6 and a photoelectric tube 8. The pulse signal generator 1 generates two driving pulse signals with a certain time interval and different pulse widths, so that the laser diode 5 generates two pulse light signals with a certain time interval and different pulse widths. The first generated pulse light signal has a wider time width, so that the to-be-tested MCP-PMT 7 is saturated. The second generated pulse light signal has a narrower time width. In general, the to-be-tested MCP-PMT 7 works in a linear state under the excitation of the pulse light signal with a narrower time width. The saturation recovery characteristic of the to-be-tested MCP-PMT 7 is evaluated by using the pulse light signal with a narrower time width, which is consistent with the actual application requirement of the MCP-PMT. In addition, the saturation recovery characteristic of the to-be-tested MCP-PMT 7 under different saturation depths can be obtained by further adjusting the time width of the first generated pulse light signal. The saturation recovery characteristic of the to-be-tested MCP-PMT 7 under different recovery degrees can be obtained by further adjusting the time width of the second generated pulse light signal.

[0065] The embodiment further provides a microchannel plate photomultiplier pulse saturation recovery characteristic testing method, which adopts the microchannel plate photomultiplier pulse saturation recovery characteristic testing device and includes the following steps.

[0066] Step 1, turn on the digitizer 10 and the high-voltage source 9, set the amplitude of the driving pulse output by the first output channel of the pulse signal generator 1 to 2 V, the frequency to 1 Hz and the pulse width to 2 μs, set the amplitude of the driving pulse output by the second output channel of the pulse signal generator 1 to 4 V, the frequency to 1 Hz and the pulse width to increase from 10 ns to 4 μs in turn, and set the change range of the output delay between the first output channel and the second output channel of the pulse signal generator 1 to 100 ns-900 ms.

[0067] Step 2, turn on the pulse signal generator 1, and make the second output channel output driving pulses with the set amplitude, frequency, time interval of the change of the pulse width and change range. The power divider 2 divides the driving pulses output by the second output channel into two paths, one of which is sent to the laser diode 5 through the combiner 3 to drive the laser diode 5 to generate pulse light signals, and the other of which is sent to the digitizer 10 to trigger the digitizer 10 to start working.

[0068] Step 3: The pulsed light signal is attenuated by the light attenuation plate 6 and then incident on the MCP-PMT 7 to be tested. At the same time, the pulsed light signal is directly incident on the phototube 8. After receiving the pulsed light signal, the MCP-PMT 7 to be tested and the phototube 8 generate a light response signal and send it to the digitizer 10. The digitizer 10 converts the light response signal into a digital signal and sends it to the data processing unit 11 to obtain the output signal of the MCP-PMT 7 to be tested and the phototube 8. Figure 2 As shown, it is the output signal waveform diagram of the MCP-PMT7 and the photoelectric tube 8 to be tested when the pulse width of the driving pulse output by the second output channel of the pulse signal generator 1 is 85ns.

[0069] Step 4: The data processing unit 11 processes the output signals of the MCP-PMT 7 and the phototube 8 to be tested, calculates the output charge of the MCP-PMT 7 and the phototube 8 under different pulse width driving pulses, and then obtains the working curve of the MCP-PMT 7 to be tested. Specifically:

[0070] 4.1. Calculate the output charge Q of the MCP-PMT7 and photoelectric tube 8 under test respectively according to the following formula (unit: nC):

[0071]

[0072] Among them, V i is the amplitude of the output signal of the MCP-PMT7 or photoelectric tube 8 to be measured at the i-th sampling point, in V; R is the input impedance of the digitizer 10, in Ω; f is the sampling frequency of the digitizer 10, in GHz;

[0073] 4.2, such as Figure 3 As shown, a graph is drawn with the output charge of the phototube 8 as the horizontal axis and the output charge of the MCP-PMT 7 to be tested as the vertical axis to obtain a working curve of the MCP-PMT 7 to be tested.

[0074] Step 5. Set the pulse width of the output pulse of the second output channel to 100ns, and then make the first output channel and the second output channel of the pulse signal generator 1 output the driving pulse according to the set amplitude, frequency and pulse width, as well as the time interval and variation range of the output delay change, and the first output channel outputs before the second output channel.

[0075] Step 6: The power divider 2 divides the driving pulse output from the second output channel into two paths. One path is combined with the driving pulse output from the first output channel in the combiner 3 and then sent to the laser diode 5, driving the laser diode 5 to generate two pulse optical signals in one output cycle. The other path is sent to the digitizer 10, triggering the digitizer 10 to start working. Then, according to the method of step 3, the output signals of the MCP-PMT7 under different output delays are obtained.Figure 4 Fig. 4 shows the output signal waveforms of the MCP-PMT 7 and the phototube 8 when the output delay of the pulse signal generator is 1 μs.

[0076] Step 7, the data processing unit 11 normalizes the output signals of the MCP-PMT 7 at different output delays according to the working curve of the MCP-PMT 7 obtained in step 4, and further obtains the pulse saturation recovery characteristic curve of the MCP-PMT 7. Specifically:

[0077] 7.1, the output charge amount Q1 of the output signals of the MCP-PMT 7 and the phototube 8 corresponding to the driving pulse output by the second output channel of the pulse signal generator 1 is calculated according to the method of step 4.1;

[0078] 7.2, the output charge amount Q of the MCP-PMT 7 under the driving pulse with the set pulse width of the second output channel of the pulse signal generator 1 is obtained according to the working curve of the MCP-PMT 7 obtained in step 4; 设定

[0079] 7.3, the normalization of Q1 is performed with Q 设定 to obtain the normalized output of the MCP-PMT 7;

[0080] 7.4, a curve is drawn with the output delay between the first output channel and the second output channel of the pulse signal generator 1 as the horizontal axis and the normalized output of the MCP-PMT 7 as the vertical axis, to obtain the pulse saturation recovery characteristic curve of the MCP-PMT 7 as shown in Figure 5 . In the pulse saturation recovery characteristic curve of the MCP-PMT 7, the pulse width of the saturation (i.e. the driving pulse output by the first output channel of the pulse signal generator 1) of the MCP-PMT 7 is 2 μs, the saturation depth is 53.6%, and the pulse width of the monitoring pulse (i.e. the driving pulse output by the second output channel of the pulse signal generator 1) for monitoring the recovery degree of the MCP-PMT 7 is 100 ns.

[0081] Step 8, the pulse width of the driving pulse output by the first output channel of the pulse signal generator 1 is adjusted, the pulse width of the driving pulse output by the second output channel is unchanged, and the pulse saturation recovery characteristic curve of the MCP-PMT 7 at different saturation depths is obtained according to the method of steps 5-7 as shown in Figure 6 . The saturation depth is calculated as follows:

[0082] As shown in Figure 3 , the linear fitting of the linear region of the working curve of the MCP-PMT 7 is performed to obtain the linear fitting value of the working curve of the MCP-PMT 7, and then the saturation depth D of the MCP-PMT 7 under the driving pulse with different pulse widths is calculated according to the following formula:

[0083] ​

[0084] wherein Q 饱和 is the output charge amount of the saturation region in the working curve of the MCP-PMT 7 to be tested, Q 拟合 is the linear fitting value corresponding to the output charge amount of the saturation region in the working curve of the MCP-PMT 7 to be tested.

[0085] According to the above method, the saturation depth is 26.4% when the pulse width is 1 μs, the saturation depth is 53.6% when the pulse width is 2 μs, and the saturation depth is 66.9% when the pulse width is 3 μs.

[0086] Step 9, keeping the pulse width of the driving pulse output by the first output channel of the pulse signal generator 1 unchanged, adjusting the pulse width of the driving pulse output by the second output channel to be less than that of the first output channel, and then obtaining the pulse saturation recovery characteristic curve of the MCP-PMT 7 to be tested under different recovery degrees as shown in Figure 7 The recovery degree is defined as the output charge amount of the MCP-PMT 7 to be tested when it recovers from the saturation state to the linear working state. In this embodiment, the pulse width of the driving pulse output by the second output channel of the pulse signal generator 1 is used to represent the recovery degree. The greater the pulse width, the greater the recovery degree, and the smaller the pulse width, the smaller the recovery degree.

[0087] It should be noted that, Figure 6 and Figure 7 In the above formula, channel 1 refers to the pulse width of the driving pulse output by the first output channel of the pulse signal generator 1, and channel 2 refers to the pulse width of the driving pulse output by the second output channel of the pulse signal generator 1.

[0088] The pulse saturation recovery characteristic test device for the micro-channel plate photomultiplier tube is constructed in this embodiment, and a pulse saturation recovery characteristic test method for the micro-channel plate photomultiplier tube is provided. The pulse saturation recovery characteristic curve of the MCP-PMT to be tested consistent with the actual application can be obtained, and the saturation recovery characteristic curve under different saturation depths and the saturation recovery characteristic curve under different recovery degrees can also be obtained.

Claims

1. A method for testing the pulse saturation recovery characteristics of a microchannel plate photomultiplier, which employs a testing device for the pulse saturation recovery characteristics of a microchannel plate photomultiplier, comprising a dark box (4), a laser diode (5), a light attenuator (6) and a phototube (8) arranged in the dark box (4), and a pulse signal generator (1), a power divider (2), a combiner (3), a high voltage source (9), a digitizer (10) and a data processing unit (11); a first output channel of the pulse signal generator (1) is connected with one input end of the combiner (3), a second output channel is connected with an input end of the power divider (2), one output end of the power divider (2) is connected with another input end of the combiner (3), another output end is connected with a trigger end of the digitizer (10), and an output end of the combiner (3) is connected with a driving end of the laser diode (5); the first output channel and the second output channel of the pulse signal generator (1) have a continuously adjustable output delay, and the pulse width of the driving pulse output by the first output channel is greater than that of the second output channel; the pulse signal generator (1) is used to drive the laser diode (5) to generate a pulse light signal and trigger the digitizer (10); the combiner (3) is used to combine the driving pulse output by the first output channel of the pulse signal generator (1) and the driving pulse output by one output end of the power divider (2) into one, so as to drive the laser diode (5) to generate two pulse light signals in one output period; the phototube (8) is arranged at the rear end of the laser diode (5), one side of which is arranged with a to-be-tested MCP-PMT (7), and the light attenuator (6) is arranged at the front end of the to-be-tested MCP-PMT (7); the phototube (8) is used to monitor the light intensity change of the laser diode (5), and the light attenuator (6) is used to attenuate the light intensity incident on the to-be-tested MCP-PMT (7); the light cathode incident windows of the to-be-tested MCP-PMT (7) and the phototube (8) are both located in the light range of the laser diode (5), the high voltage input ends are respectively connected with the output ends of the high voltage source (9), the anode output ends are respectively connected with two input channels of the digitizer (10), and the output end of the digitizer (10) is connected with the data processing unit (11); characterized in that comprising the following steps: Step 1, turn on the digitizer (10) and the high voltage source (9), set the amplitude, frequency and pulse width of the driving pulse output by the first output channel of the pulse signal generator (1), the time interval and change range of the amplitude, frequency and pulse width of the driving pulse output by the second output channel, and the change range and time interval of the output delay between the first output channel and the second output channel of the pulse signal generator (1). Step 2, open the pulse signal generator (1), the second output channel outputs driving pulse according to the set amplitude, frequency, pulse width variation time interval and variation range, the power divider (2) divides the driving pulse output by the second output channel into two paths, one of which is sent to the laser diode (5) through the combiner (3) to drive the laser diode (5) to generate a pulse light signal, and the other is sent to the digitizer (10) to trigger the digitizer (10) to start working; Step 3, the pulse light signal is attenuated by the light attenuation sheet (6) and then incident on the to-be-measured MCP-PMT (7), and the pulse light signal is directly incident on the phototube (8), the to-be-measured MCP-PMT (7) and the phototube (8) generate light response signals after receiving the pulse light signal, and send the light response signals to the digitizer (10), the digitizer (10) converts the light response signals into digital signals and sends them to the data processing unit (11), and the output signals of the to-be-measured MCP-PMT (7) and the phototube (8) are obtained; Step 4, the data processing unit (11) processes the output signals of the to-be-measured MCP-PMT (7) and the phototube (8), calculates the output charge of the to-be-measured MCP-PMT (7) and the phototube (8) under different pulse width driving pulses, and then obtains the working curve of the to-be-measured MCP-PMT (7); Step 5, set the pulse width of the driving pulse output by the second output channel of the pulse signal generator (1) to a fixed pulse width smaller than the pulse width of the driving pulse output by the first output channel, and then make the first output channel and the second output channel output driving pulse according to the set amplitude, frequency and pulse width, and the range and time interval of the output delay variation; Step 6, the power divider (2) divides the driving pulse output by the second output channel of the pulse signal generator (1) into two paths, one of which is combined with the driving pulse output by the first output channel in the combiner (3) to form a path, and then sent to the laser diode (5) to drive the laser diode (5) to generate two pulse light signals in one output cycle, and the other is sent to the digitizer (10) to trigger the digitizer (10) to start working, and then the output signal of the to-be-measured MCP-PMT (7) under different output delays is obtained according to the method of step 3; Step 7, the data processing unit (11) normalizes the output signal of the to-be-measured MCP-PMT (7) under different output delays according to the working curve of the to-be-measured MCP-PMT (7) obtained in step 4, and then obtains the pulse saturation recovery characteristic curve of the to-be-measured MCP-PMT (7).

2. The method of claim 1, wherein the microchannel plate photomultiplier tube pulse saturation recovery characteristic test method is characterized by: The distance between the laser diode (5) and the to-be-measured MCP-PMT (7) and the phototube (8) is 20 cm.

3. The method of claim 2, wherein the microchannel plate photomultiplier tube pulse saturation recovery characteristic test method is characterized by: The light attenuation sheet (6) adopts a reflective neutral density light attenuation sheet; The digitizer (10) adopts an oscilloscope or a plug-in digitizer.

4. The method of claim 3, wherein the method further comprises: The dark box (4) is an iron cabinet box body with matte black paint sprayed on the inside.

5. The method of claim 1-4, wherein the method is a method of testing the pulse saturation recovery characteristics of a microchannel plate photomultiplier tube, characterized by, Further comprising: Step 8, adjusting the pulse width of the driving pulse output from the first output channel of the pulse signal generator (1), while keeping the pulse width of the driving pulse output from the second output channel unchanged, and obtaining the pulse saturation recovery characteristic curve of the MCP-PMT (7) to be tested at different saturation depths according to the method of Step 5 to Step 7; The saturation depth is calculated as follows: Perform a linear fit on the linear region of the working curve of the MCP-PMT (7) to be tested obtained in step 4 to obtain the linear fitting value of the working curve of the MCP-PMT (7) to be tested, and then calculate the saturation depth D of the MCP-PMT (7) to be tested under different pulse widths according to the following formula: wherein Q 饱和 is the output charge amount of the saturation region in the working curve of the MCP-PMT (7) to be measured, Q 拟合 is the linear fitting value corresponding to the output charge amount of the saturation region in the working curve of the MCP-PMT (7) to be measured.

6. The method of claim 5, wherein the microchannel plate photomultiplier tube pulse saturation recovery characteristic test method is characterized by, Also includes: Step 9: Keep the pulse width of the driving pulse output from the first output channel of the pulse signal generator (1) unchanged, adjust the pulse width of the driving pulse output from the second output channel to be smaller than that of the first output channel, and then obtain the pulse saturation recovery characteristic curve of the MCP-PMT (7) to be tested under different recovery degrees according to the method of steps 5 to 7.

7. The method of claim 6, wherein the method further comprises: Step 4 is as follows: 4.

1. Calculate the output charge Q of the MCP-PMT (7) and phototube (8) to be tested respectively according to the following formula: wherein R is the input impedance of the digitizer (10), f is the sampling frequency of the digitizer (10); V i is the amplitude of the output signal of the MCP-PMT (7) or phototube (8) to be measured at the i-th sampling point; 4.

2. With the output charge of the phototube (8) as the horizontal axis and the output charge of the MCP-PMT (7) to be tested as the vertical axis, a graph is drawn to obtain the working curve of the MCP-PMT (7) to be tested.

8. The method of claim 7, wherein the method further comprises: Step 7 is as follows: 7.

1. Calculate the output charge Q1 of the output signal of the MCP-PMT (7) to be tested corresponding to the output pulse of the second output channel of the pulse signal generator (1) according to the method of step 4.1; 7.2, get the output charge Q of the MCP-PMT (7) under the driving pulse of the second output channel of the pulse signal generator (1) set pulse width according to the working curve of the MCP-PMT (7) to be tested obtained in step 4 设定 ; 7.3, with Q 设定 normalizing Q1 to obtain a normalized output of the MCP-PMT (7) under test; 7.

4. A graph is drawn with the output delay between the first output channel and the second output channel of the pulse signal generator (1) as the horizontal axis and the normalized output of the MCP-PMT (7) to be tested as the vertical axis to obtain a pulse saturation recovery characteristic curve of the MCP-PMT (7) to be tested.

9. The method of claim 8, wherein the method further comprises: determining the pulse saturation recovery characteristics of the microchannel plate photomultiplier tube by: applying a series of pulses to the microchannel plate photomultiplier tube; and measuring the output of the microchannel plate photomultiplier tube in response to the series of pulses. In step 5, the amplitude of the driving pulse output from the first output channel of the pulse signal generator (1) is 2V, the frequency is 1Hz, and the pulse width is 2μs, the amplitude of the driving pulse output from the second output channel is 4V, the frequency is 1Hz, and the pulse width is 100ns, and the output delay between the first output channel and the second output channel varies in the range of 100ns to 900ms.

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