A scintillation optical fiber performance testing system and method

Abstract

The present application discloses a scintillation fiber performance test system and method, which relates to the field of optical component testing. The scintillation fiber performance test system includes an absolute gain test module, a SiPM test module, an attenuation time test module and a computer; wherein the absolute gain test module includes a pulse generator, a laser transmitter, a filter, a collimator, a SiPM, a preamplifier, a postamplifier, a coincidence circuit and a QDC; the SiPM test module includes a radiation source, a collimator, a scintillation fiber, a SiPM, a preamplifier, a postamplifier, a constant ratio timer, a coincidence circuit and a QDC; the attenuation time test module includes a radiation source, a collimator, a scintillation fiber, a SiPM, a preamplifier and an oscilloscope. Based on the scintillation fiber performance test system, the attenuation length, bending loss, light yield and attenuation time of the scintillation fiber can be tested, and the test efficiency and accuracy can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of optical component testing, and in particular to a scintillation optical fiber performance testing system and method. Background Art

[0002] In the fields of modern physics research, medical imaging, and security detection, high-energy particle detection technology plays a vital role. Among them, scintillation fiber detectors have been widely studied and applied due to their unique advantages. The scintillation fiber detector consists of a scintillation fiber and a photodetector. Its working principle is that high-energy particles interact with the scintillation fiber to generate a light signal, which is then transmitted to the photodetector through the optical fiber for photoelectric signal conversion, and finally the radiation-related information is obtained through analysis. In the scintillation fiber detector, the light yield, decay time, light signal transmission and other characteristics of the scintillation fiber are crucial to the overall performance of the detector. For example, the light yield affects the signal collection efficiency of the detector, the decay time affects the detector's signal detection and resolution capabilities, and the light signal transmission characteristics affect the integrity of the signal. Therefore, testing the performance of the scintillation fiber is a key guarantee to ensure the subsequent development of the scintillation fiber detector. This field urgently needs a system and method that can simultaneously test the transmission performance and luminescence performance of the scintillation fiber and take into account the test effect. Summary of the invention

[0003] In response to the needs of scintillation optical fiber performance testing, the present application provides a scintillation optical fiber performance testing system and method, which can take into account the transmission performance and luminescence performance of the scintillation optical fiber and improve the efficiency and accuracy of the test.

[0004] To achieve the above objectives, this application provides the following solutions.

[0005] On the one hand, the present application provides a scintillation optical fiber performance test system, including: a SiPM (Silicon photomultiplier) absolute gain test module, a SiPM test module, a decay time test module and a computer;

[0006] The absolute gain test module includes a pulse generator, a laser emitter, a filter, a first collimator, a first SiPM, a first preamplifier, a first postamplifier, a first coincidence circuit and a first charge-to-digital converter (QDC); wherein the two outputs of the pulse generator are respectively connected to the input end of the laser emitter and the first input end of the first coincidence circuit; the filter, the first collimator, the first SiPM, the first preamplifier and the first postamplifier are sequentially arranged on the output light path of the laser emitter; the output end of the first postamplifier is respectively connected to the second input end of the first coincidence circuit and the second input end of the first charge-to-digital converter; the output end of the first coincidence circuit is connected to the first input end of the first charge-to-digital converter; the output end of the first charge-to-digital converter is connected to the computer;

[0007] The SiPM test module includes a first radiation source, a second collimator, a scintillation fiber, a second SiPM, a second preamplifier, a second postamplifier, a first constant ratio timer, a third SiPM, a third preamplifier, a third postamplifier, a second constant ratio timer, a second coincidence circuit and a second charge-to-digital converter; wherein the first radiation source is placed in the second collimator; the high-energy particle radiation beam emitted by the first radiation source passes through the second collimator and hits the scintillation fiber; the scintillation fiber generates an optical signal, which is transmitted to the second SiPM and the third SiPM located at both ends of the scintillation fiber through the inside of the optical fiber; the electrical signal output by the second SiPM passes through the second preamplifier, the third postamplifier, the second constant ratio timer, the second coincidence circuit and the second charge-to-digital converter in sequence. After being processed by the second post-stage amplifier and the first constant ratio timer, the generated bipolar signal is input to the first input end of the second coincidence circuit; after the electrical signal output by the third SiPM is processed by the third pre-stage amplifier, the third post-stage amplifier and the second constant ratio timer in sequence, the generated bipolar signal is input to the second input end of the second coincidence circuit; the output end of the second coincidence circuit is connected to the first input end of the second charge digital converter; the output end of the second post-stage amplifier is connected to the second input end of the second charge digital converter; the output end of the third post-stage amplifier is connected to the third input end of the second charge digital converter; the output end of the second charge digital converter is connected to the computer;

[0008] The attenuation time test module includes a second radiation source, a third collimator, a scintillation fiber, a fourth SiPM, a fourth pre-amplifier and an oscilloscope; wherein the second radiation source is placed in the third collimator; the high-energy particle radiation beam emitted by the second radiation source passes through the third collimator and hits the scintillation fiber; the optical signal generated by the scintillation fiber is transmitted to the fourth SiPM through the inside of the optical fiber, and is converted into an electrical signal by the fourth SiPM and then transmitted to the fourth pre-amplifier; the output end of the fourth pre-amplifier is connected to the input end of the oscilloscope; and the output end of the oscilloscope is connected to the computer.

[0009] Optionally, the first pre-amplifier, the second pre-amplifier, the third pre-amplifier and the fourth pre-amplifier are all current sensitive pre-amplifiers with a gain of 5-10 times;

[0010] The first post-stage amplifier, the second post-stage amplifier and the third post-stage amplifier all adopt a two-stage amplifier circuit based on an OP amplifier, and the amplification factor is 10-100 times.

[0011] On the other hand, the present application provides a scintillation optical fiber performance testing method based on the scintillation optical fiber performance testing system; the scintillation optical fiber performance testing method comprises:

[0012] Test the absolute gain of SiPM based on the absolute gain test module;

[0013] Test the optical yield, attenuation length and bending loss of scintillating optical fibers based on SiPM test modules;

[0014] The decay time of the scintillation optical fiber is tested based on the decay time test module.

[0015] Optionally, the testing the absolute gain of the SiPM based on the absolute gain testing module specifically includes:

[0016] The pulse generator is used to output a driving signal, wherein one channel of the driving signal is used to control the light intensity and frequency of the laser emitter, and the other channel is used as a trigger signal of the first coincidence circuit;

[0017] The laser emitter is used to emit a photon beam of a specific wavelength, and the emitted photon beam is transmitted to the sensitive area surface of the first SiPM through the filter and the first collimator, and the optical signal is converted into an electrical signal by the first SiPM and then output to the first pre-amplifier;

[0018] The first preamplifier is used to amplify the electrical signal from the first SiPM and perform current-voltage signal conversion, and also has a signal polarity reversal function;

[0019] The first post-stage amplifier is used to amplify the electrical signal from the first pre-stage amplifier and reduce the noise introduced during the amplification process;

[0020] The first coincidence circuit is used to trigger the first charge digital converter to acquire charge information when the output signal of the first post-stage amplifier and the trigger signal are input simultaneously; the charge information is the charge amount acquired by each channel of the first charge digital converter;

[0021] The computer calculates the absolute gain of the SiPM according to the charge information acquired by the first charge-to-digital converter.

[0022] Optionally, the computer calculates the absolute gain of the SiPM according to the charge information acquired by the first charge-to-digital converter, specifically including:

[0023] Using formula Calculating the absolute gain of SiPM ;in is the channel number corresponding to the charge spectrum peak of the first charge digital converter; For the The amount of charge acquired by the channel; A total charge amount obtained by the first charge-to-digital converter; is the amplification factor of the first pre-amplifier; is the amplification factor of the first post-stage amplifier; Represents the charge of an electron.

[0024] Optionally, the testing of the light yield and attenuation length of the scintillation optical fiber based on the SiPM test module specifically includes:

[0025] The first radiation source is used to emit a high-energy particle radiation beam;

[0026] The second collimator is used to direct the high-energy particle radiation beam to a point on the scintillating fiber, called the radioluminescent point;

[0027] The optical signal generated at the radiation luminescence point is transmitted to the two ends of the scintillation optical fiber through the inside of the optical fiber, and then transmitted to the second SiPM and the third SiPM;

[0028] The second SiPM converts the optical signal into an electrical signal and outputs the electrical signal to the second pre-amplifier, and the electrical signal is amplified by the second pre-amplifier and the second post-amplifier in sequence and then input to the first constant ratio timer;

[0029] The first constant ratio timer processes the electrical signal from the second post-stage amplifier, delays the electrical signal on the one hand, and reversely attenuates the electrical signal on the other hand, superimposes the processed delayed signal and reversely attenuated signal, and converts the original unipolar signal into a first bipolar signal after superposition;

[0030] The third SiPM converts the optical signal into an electrical signal and outputs the electrical signal to the third pre-amplifier, and then the electrical signal is amplified by the third pre-amplifier and the third post-amplifier in sequence and then input to the second constant ratio timer;

[0031] The second constant ratio timer processes the electrical signal from the third post-stage amplifier, delays the electrical signal on the one hand, and reversely attenuates the electrical signal on the other hand, superimposes the processed delayed signal and reversely attenuated signal, and converts the original unipolar signal into a second bipolar signal after superposition;

[0032] The second coincidence circuit is used to trigger the second charge digital converter to obtain charge information at the second post-stage amplifier and the third post-stage amplifier respectively when two bipolar signals are input simultaneously; the charge information is the charge amount obtained by the second charge digital converter for each channel;

[0033] The computer calculates the light yield of the scintillating fiber according to the charge information obtained from the second post-stage amplifier and the third post-stage amplifier and the absolute gain of the SiPM;

[0034] The computer calculates the attenuation length of the scintillating optical fiber according to the charge information obtained from the second post-stage amplifier and the third post-stage amplifier.

[0035] Optionally, the computer calculates the light yield of the scintillation fiber according to the acquired charge information and the absolute gain of the SiPM, specifically including:

[0036] The computer calculates the total charge detected by the first SiPM based on the charge information obtained from the second post-amplifier. , calculate the total charge detected by the second SiPM according to the charge information obtained from the third post-amplifier ;

[0037] Using formula Calculate the total charge detected by the SiPM test module ;

[0038] Using formula Calculate the total number of photons detected by the two SiPMs ;in is the amplification factor of the second pre-stage amplifier, which is the same as the amplification factor of the third pre-stage amplifier; is the amplification factor of the second post-stage amplifier, which is the same as the amplification factor of the third post-stage amplifier;

[0039] Using formula Calculating the Light Yield of Scintillating Fibers ;in is the photon detection efficiency of the second SiPM or the third SiPM corresponding to the wavelength of photons emitted by the optical fiber.

[0040] Optionally, the computer calculates the attenuation length of the scintillation optical fiber according to the charge information obtained from the second post-stage amplifier and the third post-stage amplifier, specifically including:

[0041] Using formula calculate and , used to characterize the attenuation length of the scintillation fiber; and are the corresponding charges generated by the cladding light and the core light respectively; is the distance from the radioluminescent point to the surface of the sensitive area of ​​the second SiPM or the third SiPM; and are the attenuation length constants corresponding to the cladding and core layers, respectively.

[0042] Optionally, the testing of the bending loss of the scintillation optical fiber based on the SiPM test module specifically includes:

[0043] The length of use is Straight fiber time Test within, get time The total charge detected by the internal SiPM test module ;

[0044] Place the scintillating fiber in grooves with different curvature radii and bend them at different angles , use the second collimator to direct the high-energy particle radiation beam to one end of the scintillating fiber, and use the SiPM test module to test and obtain the time The total charge detected by the internal SiPM test module ;

[0045] Using formula Calculate the bending loss rate of different curvature radii under unit angle , which is used to characterize the bending loss of scintillating optical fibers at different curvature radii.

[0046] Optionally, the attenuation time of the scintillation optical fiber is tested based on the attenuation time test module, specifically comprising:

[0047] The high-energy particle radiation beam emitted by the second radiation source is directed to a point on the scintillating optical fiber by using a third collimator, which is called a radioluminescent point;

[0048] The optical signal generated at the radioluminescent point is transmitted to the fourth SiPM through the optical fiber, and the optical signal is converted into an electrical signal by the fourth SiPM and then output to the fourth pre-amplifier;

[0049] The fourth pre-amplifier is used to amplify the electrical signal from the fourth SiPM and perform current-voltage signal conversion, and also has a signal polarity reversal function;

[0050] The oscilloscope is used to display the electrical signal converted by the fourth pre-amplifier as a curve of signal amplitude changing with time;

[0051] Computers are used to apply formula Fitting signal amplitude Over time The decay constant is calculated from the curve of , used to characterize the decay time of scintillation fiber; is the correction constant for the fitting curve; is the correction coefficient of the fitting curve.

[0052] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0053] The present application provides a scintillation fiber performance test system and method, which can directly test the attenuation length and bending loss of the scintillation fiber based on the SiPM test module; can test the absolute gain of the SiPM based on the absolute gain test module, and further test the light yield of the scintillation fiber based on the SiPM test module; can test the decay time of the scintillation fiber based on the decay time test module. It can be seen that the scintillation fiber performance test system and method of the present application can be used for both the transmission performance test and the luminescence performance test of the scintillation fiber, and the system operation method is simple, the test principle is clear, and the charge information obtained in one test can be used for multiple performance parameter calculations at the same time, which greatly improves the test efficiency. Through the structural design of the absolute gain test module, the SiPM test module and the decay time test module, the accuracy of the test results is further improved, which provides an important data acquisition means for evaluating the luminescence performance, transmission performance and subsequent related detector development of the scintillation fiber. In addition, the SiPM test module can be used for the attenuation length, bending loss and light yield test of the scintillation fiber, which greatly reduces the system volume, weight and manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 It is a functional schematic diagram of the scintillation optical fiber performance test system;

[0056] Figure 2 It is a structural diagram of the absolute gain test module;

[0057] Figure 3It is a structural schematic diagram of the SiPM test module;

[0058] Figure 4 It is a structural diagram of the decay time test module;

[0059] Figure 5 is the signal amplitude in a certain embodiment Over time Schematic diagram of the change curve. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] The purpose of this application is to provide a scintillation optical fiber performance testing system and method to improve the efficiency and accuracy of scintillation optical fiber transmission performance and luminescence performance testing.

[0062] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0063] The present invention provides a scintillation fiber performance test system, including: an absolute gain test module, a SiPM test module, a decay time test module and a computer. The scintillation fiber performance test system has the following functions: Figure 1 As shown, based on the absolute gain test module, SiPM test module and attenuation time test module, the transmission performance test and luminescence performance test of the scintillation optical fiber can be performed, wherein the transmission performance test includes attenuation length test and bending loss test, and the luminescence performance test includes light yield test and attenuation time test. Among them, the attenuation length test and bending loss test of the scintillation optical fiber can be directly performed based on the SiPM test module. The light yield test needs to perform the SiPM absolute gain test based on the absolute gain test module to obtain the absolute gain of the SiPM. After that, the test can be continued based on the SiPM test module. The decay time test is directly performed based on the decay time test module.

[0064] Figure 2 The absolute gain test module structure is shown in FIG. Figure 2As shown, the absolute gain test module includes a pulse generator, a laser emitter, a filter, a first collimator, a first SiPM, a first preamplifier, a first post-amplifier, a first coincidence circuit and a first QDC. The two outputs of the pulse generator are respectively connected to the input end of the laser emitter and the first input end of the first coincidence circuit. The filter, the first collimator, the first SiPM, the first preamplifier and the first post-amplifier are sequentially arranged on the output light path of the laser emitter. The output end of the first post-amplifier is respectively connected to the second input end of the first coincidence circuit and the second input end of the first QDC. The output end of the first coincidence circuit is connected to the first input end of the first QDC. The output end of the first QDC is connected to the computer (not shown in the figure).

[0065] The pulse generator is used to emit a driving signal, one of which is used to control the luminous intensity and frequency of the laser emitter, and the other is used as a trigger signal of the first coincidence circuit.

[0066] The laser emitter is used to emit a photon beam of a specific wavelength, and the emitted photon beam is transmitted to the sensitive area surface of the first SiPM through a filter and a first collimator in sequence.

[0067] The filter is used to reduce the light flux intensity of the laser transmitter, control the light reaching the surface of the first SiPM sensitive area to belong to the weak light category, prevent the SiPM from receiving a large flow of photons that exceeds the module design tolerance range, and cause the internal components of the device to overload or be damaged, thereby causing burning.

[0068] The first collimator is used to calibrate the direction of the photon beam to ensure that the photon beam propagates along the desired pinhole path to the sensitive area surface of the first SiPM.

[0069] The first SiPM is used as a photoelectric conversion device to receive the optical signal from the first collimator and convert it into an electrical signal.

[0070] The first preamplifier is used to amplify the electrical signal from the first SiPM. The first preamplifier is a current-sensitive preamplifier, which is used as an IV conversion and amplification device. Its amplification factor is 5-10 times and has a signal polarity reversal function.

[0071] The first post-stage amplifier is used to amplify the electrical signal from the first pre-stage amplifier. The first post-stage amplifier is a two-stage amplifier circuit based on an OP amplifier, and its amplification factor is 10-100 times. In addition to amplifying the signal, it also has the function of reducing the noise introduced in the amplification process and improving the signal-to-noise ratio of the detector.

[0072] The first coincidence circuit is used to identify the signal from the laser emitter and the signal from the pulse generator. Only when the electrical signal from the first post-stage amplifier and the trigger signal from the pulse generator are received at the same time, will it be regarded as a signal detected, triggering the first QDC to start collecting charge information, thereby reducing experimental measurement errors.

[0073] The first QDC is used to obtain and analyze the charge information of the system. The charge information here is the charge amount obtained by the first QDC for each channel. ,in . is the channel number corresponding to the first QDC charge spectrum peak. The computer can calculate the absolute gain of the SiPM based on the charge information obtained by the first QDC. .

[0074] Figure 3 The SiPM test module structure is shown. The SiPM test module can be used to perform attenuation length test, bending loss test and optical yield test of scintillation optical fiber. Figure 3 As shown, the SiPM test module includes a first radiation source, a second collimator, a scintillation fiber 301, a second SiPM, a second preamplifier, a second postamplifier, a first constant ratio timer, a third SiPM, a third preamplifier, a third postamplifier, a second constant ratio timer, a second coincidence circuit and a second QDC. The first radiation source is placed in the second collimator. A SiPM is installed at each end of the scintillation fiber, namely the second SiPM and the third SiPM. The high-energy particle radiation beam emitted by the first radiation source passes through the second collimator and hits the scintillation fiber 301. The scintillation fiber 301 generates an optical signal, which is transmitted to the second SiPM and the third SiPM located at both ends of the scintillation fiber through the inside of the optical fiber. The electrical signal output by the second SiPM is processed by the second preamplifier, the second postamplifier and the first constant ratio timer in sequence, and the generated bipolar signal is input to the first input end of the second coincidence circuit. The electrical signal output by the third SiPM is processed by the third preamplifier, the third postamplifier and the second constant ratio timer in sequence, and the generated bipolar signal is input to the second input end of the second coincidence circuit. The output end of the second coincidence circuit is connected to the first input end of the second charge digital converter. The output end of the second post-stage amplifier is connected to the second input end of the second charge digital converter. The output end of the third post-stage amplifier is connected to the third input end of the second charge digital converter. The output end of the second charge digital converter is connected to the computer.

[0075] The first radiation source is used to provide a high-energy particle radiation beam, and the type of particles emitted by the first radiation source after decay needs to match the type of particles that the scintillation fiber responds to.

[0076] The second collimator is used to direct the high-energy particle radiation beam to a point on the scintillating optical fiber (called a radioluminescent point), which helps to reduce scattered radiation around the radiation beam and improve the measurement accuracy.

[0077] The second SiPM and the third SiPM have similar functions to the first SiPM, and are also used as photoelectric conversion devices to receive optical signals from the scintillation optical fiber and convert them into electrical signals.

[0078] Similarly, the second pre-amplifier and the third pre-amplifier have the same functions as the first pre-amplifier. The second post-amplifier and the third post-amplifier have the same functions as the first post-amplifier. The second SiPM converts the optical signal into an electrical signal and outputs it to the second pre-amplifier, which is amplified by the second pre-amplifier and the second post-amplifier in sequence and then input into the first constant ratio timer. The third SiPM converts the optical signal into an electrical signal and outputs it to the third pre-amplifier, which is amplified by the third pre-amplifier and the third post-amplifier in sequence and then input into the second constant ratio timer.

[0079] The first constant ratio timer and the second constant ratio timer have the same function, and are both used to reduce the impact of the signal leading edge. The first constant ratio timer and the second constant ratio timer process the two electrical signals from the second SiPM and the third SiPM respectively, delaying them on the one hand and reversely attenuating the electrical signals on the other hand, superimposing the processed delayed signal and the reverse attenuated signal, and converting the original unipolar signal into a bipolar signal after superposition; and zero-crossing counting is adopted, at which time the phase difference between the input and output electrical signals is not affected by the signal size, thereby improving the time accuracy of the output signal.

[0080] The second coincidence circuit is used to trigger the second QDC to obtain charge information at the second post-stage amplifier and the third post-stage amplifier respectively when two bipolar signals are input simultaneously; the charge information collected at this time is the charge amount obtained by each channel of the second QDC.

[0081] The computer can calculate the attenuation length of the scintillating fiber based on the charge information obtained from the second and third post-stage amplifiers, and further calculate the light yield of the scintillating fiber based on the charge information obtained from the second and third post-stage amplifiers and the absolute gain of the SiPM.

[0082] In addition, by bending the scintillating optical fiber at different angles and then using the SiPM test module to perform a bending loss test, the bending loss of the scintillating optical fiber at different curvature radii can be tested.

[0083] Figure 4 The decay time test module structure is shown. Figure 4As shown, the attenuation time test module includes a second radiation source, a third collimator, a scintillation fiber, a fourth SiPM, a fourth preamplifier and an oscilloscope. The second radiation source is placed in the third collimator. The high-energy particle radiation beam emitted by the second radiation source passes through the third collimator and hits the scintillation fiber 301. The optical signal generated by the scintillation fiber 301 is transmitted to the fourth SiPM through the inside of the optical fiber, and is converted into an electrical signal by the fourth SiPM and then transmitted to the fourth preamplifier. The output end of the fourth preamplifier is connected to the input end of the oscilloscope. The output end of the oscilloscope is connected to the computer.

[0084] The second radiation source has the same function as the first radiation source, and is used to provide a high-energy particle radiation beam. The type of particles emitted by the radiation source after decay matches the type of particles that the scintillation fiber responds to.

[0085] The third collimator has the same function as the second collimator and is used to direct the high-energy particle radiation beam to a point on the scintillating optical fiber (called the radioluminescent point), which helps to reduce scattered radiation around the radiation beam and improve the accuracy of measurement.

[0086] The fourth SiPM has the same function as the second SiPM and the third SiPM, and is used as a photoelectric conversion device to receive the optical signal from the scintillation optical fiber and convert it into an electrical signal.

[0087] The fourth preamplifier has similar functions to the second and third preamplifiers and is used to amplify the electrical signal from the fourth SiPM. The preamplifier is a current-sensitive preamplifier and is used here as an IV conversion and amplification device with an amplification factor of 5-10 times and a signal polarity reversal function.

[0088] The oscilloscope is used to observe the electrical signal converted by the fourth pre-amplifier IV, and to fit the attenuation curve of the signal from the falling edge of the signal, thereby obtaining the attenuation time characteristic of the optical fiber luminescence.

[0089] Based on the scintillation optical fiber performance test system, the present application also provides a scintillation optical fiber performance test method, including:

[0090] S1: Test the absolute gain of SiPM based on the absolute gain test module.

[0091] The entire experiment of SiPM absolute gain test should be carried out under light-proof conditions. Figure 2 When performing SiPM absolute gain test, first set the signal frequency of the pulse generator And the amplitude , the pulse generator outputs a driving signal, one for controlling the luminous intensity and frequency of the laser emitter, and one for serving as a trigger signal for the first coincidence circuit. The photon beam of a specific wavelength output by the laser emitter, after attenuation by the filter and calibration by the first collimator, enters the sensitive area surface of the first SiPM to generate an electrical signal. It is then input into the first preamplifier and amplified by a factor of Then it is input into the first post-amplifier and amplified by The first coincidence circuit is amplified by the post-stage amplifier and finally input into the first coincidence circuit. When the first coincidence circuit measures the signals from the pulse generator and the first post-stage amplifier at the same time, it is regarded as a valid signal to trigger the first QDC to record the signal from the first post-stage amplifier and obtain the charge amount corresponding to each channel of the QDC. , and record the amplitude and time information of the signal at the same time. The computer can calculate the absolute gain of SiPM through the amplification factor of each level of the amplifier circuit and the charge of all channels on the first QDC. , the calculation formula is as follows:

[0092] (1)

[0093] in is the channel number corresponding to the first QDC charge spectrum peak; For the The amount of charge acquired by the channel; Then it is the total charge obtained by all channels on the first QDC; is the amplification factor of the first pre-amplifier; is the amplification factor of the first post-stage amplifier; represents the charge of the electron, .

[0094] S2: Test the optical yield, attenuation length and bending loss of the scintillation fiber based on the SiPM test module.

[0095] See also Figure 3 , take the exempted radiation source that the scintillation fiber can respond to and place it in the collimator, that is, to constitute the first radiation source and the second collimator in the SiPM test module of this application, which requires that the particle type emitted by the decay of the first radiation source matches the particle type that the scintillation fiber responds to. The high-energy particle radiation beam emitted by the first radiation source passes through the small hole on the second collimator and hits a point on the scintillation fiber (i.e., the radioluminescence point). The scintillation fiber generates an optical signal, which is transmitted through the inside of the optical fiber to the second SiPM and the third SiPM on both sides, and then passes through the pre-amplifier (i.e., the second pre-amplifier, the third pre-amplifier) ​​and the post-amplifier (i.e., the second post-amplifier, the third post-amplifier), and their amplification gains are respectively , The two electrical signals first pass through the constant ratio timer (i.e., the first constant ratio timer and the second constant ratio timer). After the constant ratio timer delays, reverses, attenuates, and superimposes the signals, a bipolar signal with zero points of the two signals being independent of the output signal amplitude is obtained, and then input into the second coincidence circuit for coincidence measurement. When the two signals respond at the same time, the second QDC is triggered to obtain the signal information from the second and third post-stage amplifiers. The second QDC records the amount of charge collected for each channel. ,in . is the channel number corresponding to the second QDC charge spectrum peak.

[0096] The charge obtained from the second post-amplifier By summing, the total charge detected by the first SiPM can be calculated. The charge obtained from the third post-amplifier By summing, the total charge detected by the second SiPM can be calculated. The total charge detected by the second QDC is then calculated using the following formula: :

[0097] (2)

[0098] After testing two SiPMs, the light yield of the scintillating fiber can be obtained by the following formulas (3) and (4): :

[0099] (3)

[0100] (4)

[0101] in is the total number of photons detected by the two-way SiPM; The total charge detected by the SiPM test module, that is, the second QDC. represents the charge of the electron, . is the absolute gain of SiPM. is the gain of the second pre-amplifier, which is the same as the gain of the third pre-amplifier. is the gain of the second post-stage amplifier, which is the same as the gain of the third post-stage amplifier. is the photon detection efficiency of the SiPM (the second SiPM or the third SiPM) corresponding to the wavelength of photons emitted from the optical fiber.

[0102] For scintillating optical fibers, the photons generated by radiation are the superposition of the cladding light and the core light. Therefore, the total charge detected by the SiPM test module is The following formula holds true:

[0103] (5)

[0104] in, It is the total charge measured by the SiPM test module. and are the corresponding charges generated by the cladding light and the core light, respectively, which are usually two constants. is the distance from the radiant luminescence point to the surface of the sensitive area of ​​the second SiPM or the third SiPM; since the second SiPM or the third SiPM is located at the two ends of the scintillation fiber, either the second SiPM or the third SiPM can be used as to be calculated. and are the attenuation length constants corresponding to the cladding and core layers, respectively, which can characterize the attenuation length of the scintillation optical fiber.

[0105] Furthermore, in the bending loss test of the optical fiber, firstly, a length of Straight fiber time Test within, get time The total charge detected by the internal SiPM test module Then place the scintillating fiber in grooves with different curvature radii (other methods can also be used) and bend it at different angles. , using a second collimator to direct the high-energy particle radiation beam to one end of the scintillating fiber (i.e. Position), and use the SiPM placed at the other end (the second SiPM or the third SiPM) to test, the test time is , get the time The total charge detected by the internal SiPM test module The bending loss rate of different curvature radii can be obtained by the following formula:

[0106] (6)

[0107] in is the bending angle; It is the bending loss rate of different curvature radii under unit angle, which can characterize the bending loss of scintillation optical fiber under different curvature radii.

[0108] It can be seen that when the bending loss test is performed based on the SiPM test module, the difference from the optical yield test and attenuation length test is that not only the straight fiber needs to be tested for time In addition, it is also necessary to conduct time-lapse tests on bent optical fibers with different curvature radii. The test is carried out within the scope of the invention, so that the bending loss of the scintillating optical fiber at different curvature radii can be calculated according to the total charge detected at different curvature radii.

[0109] S3: Testing the attenuation time of the scintillation optical fiber based on the attenuation time test module.

[0110] See also Figure 4 , the second radiation source is placed in the third collimator, and the high-energy particle radiation beam passes through the small hole in the third collimator and interacts with a certain point (radioluminescent point) on the scintillating optical fiber to generate a light signal, which is converted into an electrical signal by the fourth SiPM, and the electrical signal is amplified by the fourth preamplifier, and IV conversion is performed at the same time, and then input into the oscilloscope. The oscilloscope is used to display the electrical signal converted by the fourth preamplifier as a signal amplitude Over time The change curve of Figure 5 As shown, the amplitude and time characteristics of the signal can be observed. The detailed calculation process of the decay time test is as follows.

[0111] Push the radioluminescent point to The position is approximately 0, here is the distance from the radiation luminescence point to the surface of the fourth SiPM sensitive area. At this time, the fourth SiPM is used as a photoelectric conversion device to collect light information, and then connected to an oscilloscope to observe the signal. Due to the characteristics of the luminescent material, the shape of the signal should be a pulsed exponential decay signal, and its decay constant is The time it takes for the signal to drop from 90% to 10% is about 3-4 . Use the Single function of the oscilloscope (the Single function of the oscilloscope refers to the oscilloscope working in single trigger mode) to capture a signal with a complete shape and large signal amplitude, and export it in txt data format. The txt file records the amplitude and time corresponding to each point of the waveform. Fit an exponential decay curve in the data processing software. The fitting curve is as follows:

[0112] (7)

[0113] in, The amplitude information corresponding to each signal point, also called amplitude, unit au; The time information corresponding to each signal point, in ns; is the correction coefficient of the fitting curve; is the correction constant for the fitting curve. is the decay constant, which is used to characterize the decay time of the scintillation fiber.

[0114] The decay time of the scintillation fiber can be calculated by fitting the falling edge of the signal. For example, formula (7) can be used to fit Figure 5 When the curve shown is , , .

[0115] It can be seen that the scintillation fiber performance test system based on the present application can test the transmission performance and luminescence performance of the scintillation fiber. The transmission performance test can evaluate the cost-effectiveness of the scintillation fiber in the detector, help select the most cost-effective structural solution, and help designers optimize the geometry and configuration of the detector to maximize the collection and transmission efficiency of the optical signal. The luminescence performance test can determine the intensity of the optical signal that the scintillation fiber can generate when receiving high-energy particles or radiation, so as to adjust the back-end detection circuit and detector to ensure the sensitivity of the detector. At the same time, the test results can also distinguish between the signal and interference such as noise sources that may affect the performance of the detector, so as to take appropriate measures to reduce these interferences. Through these tests, it can be ensured that the scintillation fiber can provide accurate, reliable and traceable results in various detector applications.

[0116] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A scintillation optical fiber performance test system, characterized in that: include: Absolute gain test module, SiPM test module, decay time test module and computer; The absolute gain test module includes a pulse generator, a laser transmitter, a filter, a first collimator, a first SiPM, a first preamplifier, a first postamplifier, a first coincidence circuit and a first charge-to-digital converter; The two outputs of the pulse generator are respectively connected to the input end of the laser emitter and the first input end of the first coincidence circuit; a filter, a first collimator, a first SiPM, a first preamplifier and a first post-amplifier are sequentially arranged on the output optical path of the laser emitter; the output end of the first post-amplifier is respectively connected to the second input end of the first coincidence circuit and the second input end of the first charge digital converter; the output end of the first coincidence circuit is connected to the first input end of the first charge digital converter; the output end of the first charge digital converter is connected to the computer; The SiPM test module includes a first radiation source, a second collimator, a scintillation fiber, a second SiPM, a second preamplifier, a second postamplifier, a first constant ratio timer, a third SiPM, a third preamplifier, a third postamplifier, a second constant ratio timer, a second coincidence circuit and a second charge-to-digital converter; wherein the first radiation source is placed in the second collimator; the high-energy particle radiation beam emitted by the first radiation source passes through the second collimator and hits the scintillation fiber; the scintillation fiber generates an optical signal, which is transmitted to the second SiPM and the third SiPM located at both ends of the scintillation fiber through the inside of the optical fiber; the electrical signal output by the second SiPM passes through the second preamplifier, the third postamplifier, the second constant ratio timer, the second coincidence circuit and the second charge-to-digital converter in sequence. After being processed by the second post-stage amplifier and the first constant ratio timer, the generated bipolar signal is input to the first input end of the second coincidence circuit; after the electrical signal output by the third SiPM is processed by the third pre-stage amplifier, the third post-stage amplifier and the second constant ratio timer in sequence, the generated bipolar signal is input to the second input end of the second coincidence circuit; the output end of the second coincidence circuit is connected to the first input end of the second charge digital converter; the output end of the second post-stage amplifier is connected to the second input end of the second charge digital converter; the output end of the third post-stage amplifier is connected to the third input end of the second charge digital converter; the output end of the second charge digital converter is connected to the computer; The attenuation time test module includes a second radiation source, a third collimator, a scintillation fiber, a fourth SiPM, a fourth pre-amplifier and an oscilloscope; wherein the second radiation source is placed in the third collimator; the high-energy particle radiation beam emitted by the second radiation source passes through the third collimator and hits the scintillation fiber; the optical signal generated by the scintillation fiber is transmitted to the fourth SiPM through the inside of the optical fiber, and is converted into an electrical signal by the fourth SiPM and then transmitted to the fourth pre-amplifier; the output end of the fourth pre-amplifier is connected to the input end of the oscilloscope; and the output end of the oscilloscope is connected to the computer.

2. The scintillation optical fiber performance test system according to claim 1, characterized in that: The first pre-amplifier, the second pre-amplifier, the third pre-amplifier and the fourth pre-amplifier are all current sensitive pre-amplifiers with amplification factors of 5-10 times; The first post-stage amplifier, the second post-stage amplifier and the third post-stage amplifier all adopt a two-stage amplifier circuit based on an OP amplifier, and the amplification factor is 10-100 times.

3. A method for testing the performance of a scintillation optical fiber, characterized in that: A scintillation optical fiber performance testing system based on any one of claims 1-2; The scintillation optical fiber performance testing method comprises: Test the absolute gain of SiPM based on the absolute gain test module; Test the optical yield, attenuation length and bending loss of scintillating optical fibers based on SiPM test modules; The decay time of the scintillation optical fiber is tested based on the decay time test module.

4. The scintillation optical fiber performance testing method according to claim 3, characterized in that: The absolute gain test module is used to test the absolute gain of the SiPM, specifically including: The pulse generator is used to output a driving signal, wherein one channel of the driving signal is used to control the light intensity and frequency of the laser emitter, and the other channel is used as a trigger signal of the first coincidence circuit; The laser emitter is used to emit a photon beam of a specific wavelength, and the emitted photon beam is transmitted to the sensitive area surface of the first SiPM through the filter and the first collimator, and the optical signal is converted into an electrical signal by the first SiPM and then output to the first pre-amplifier; The first preamplifier is used to amplify the electrical signal from the first SiPM and perform current-voltage signal conversion, and also has a signal polarity reversal function; The first post-stage amplifier is used to amplify the electrical signal from the first pre-stage amplifier and reduce the noise introduced during the amplification process; The first coincidence circuit is used to trigger the first charge digital converter to acquire charge information when the output signal of the first post-stage amplifier and the trigger signal are input simultaneously; the charge information is the charge amount acquired by each channel of the first charge digital converter; The computer calculates the absolute gain of the SiPM according to the charge information acquired by the first charge-to-digital converter.

5. The scintillation optical fiber performance testing method according to claim 4, characterized in that: The computer calculates the absolute gain of the SiPM according to the charge information obtained by the first charge digital converter, specifically including: Using formula Calculating the absolute gain of SiPM ;in is the channel number corresponding to the charge spectrum peak of the first charge digital converter; For the The amount of charge acquired by the channel; a total charge amount obtained by the first charge-to-digital converter; is the amplification factor of the first pre-amplifier; is the amplification factor of the first post-stage amplifier; Represents the charge of an electron.

6. The scintillation optical fiber performance testing method according to claim 5, characterized in that: The method of testing the optical yield and attenuation length of the scintillation optical fiber based on the SiPM test module specifically includes: The first radiation source is used to emit a high-energy particle radiation beam; The second collimator is used to direct the high-energy particle radiation beam to a point on the scintillating fiber, called the radioluminescent point; The optical signal generated at the radiation luminescence point is transmitted to the two ends of the scintillation optical fiber through the inside of the optical fiber, and then transmitted to the second SiPM and the third SiPM; The second SiPM converts the optical signal into an electrical signal and outputs the electrical signal to the second pre-amplifier, and the electrical signal is amplified by the second pre-amplifier and the second post-amplifier in sequence and then input to the first constant ratio timer; The first constant ratio timer processes the electrical signal from the second post-stage amplifier, delays the electrical signal on the one hand, and reversely attenuates the electrical signal on the other hand, superimposes the processed delayed signal and reversely attenuated signal, and converts the original unipolar signal into a first bipolar signal after superposition; The third SiPM converts the optical signal into an electrical signal and outputs the electrical signal to the third pre-amplifier, and then the electrical signal is amplified by the third pre-amplifier and the third post-amplifier in sequence and then input to the second constant ratio timer; The second constant ratio timer processes the electrical signal from the third post-stage amplifier, delays the electrical signal on the one hand, and reversely attenuates the electrical signal on the other hand, superimposes the processed delayed signal and reversely attenuated signal, and converts the original unipolar signal into a second bipolar signal after superposition; The second coincidence circuit is used to trigger the second charge digital converter to obtain charge information at the second post-stage amplifier and the third post-stage amplifier respectively when two bipolar signals are input simultaneously; the charge information is the charge amount obtained by each channel of the second charge digital converter; The computer calculates the light yield of the scintillating fiber according to the charge information obtained from the second post-stage amplifier and the third post-stage amplifier and the absolute gain of the SiPM; The computer calculates the attenuation length of the scintillating optical fiber according to the charge information obtained from the second post-stage amplifier and the third post-stage amplifier.

7. The scintillation optical fiber performance testing method according to claim 6, characterized in that: The computer calculates the light yield of the scintillating optical fiber according to the acquired charge information and the absolute gain of the SiPM, specifically including: The computer calculates the total charge detected by the first SiPM based on the charge information obtained from the second post-amplifier. , calculate the total charge detected by the second SiPM according to the charge information obtained from the third post-amplifier ; Using formula Calculate the total charge detected by the SiPM test module ; Using formula Calculate the total number of photons detected by the two SiPMs ;in is the amplification factor of the second pre-stage amplifier, which is the same as the amplification factor of the third pre-stage amplifier; is the amplification factor of the second post-stage amplifier, which is the same as the amplification factor of the third post-stage amplifier; Using formula Calculating the Light Yield of Scintillating Fibers ;in is the photon detection efficiency of the second SiPM or the third SiPM corresponding to the wavelength of photons emitted by the optical fiber.

8. The scintillation optical fiber performance testing method according to claim 7, characterized in that: The computer calculates the attenuation length of the scintillation optical fiber according to the charge information obtained from the second post-stage amplifier and the third post-stage amplifier, specifically including: Using formula calculate and , used to characterize the attenuation length of the scintillation fiber; and are the corresponding charges generated by the cladding light and the core light respectively; is the distance from the radioluminescent point to the surface of the sensitive area of ​​the second SiPM or the third SiPM; and are the attenuation length constants corresponding to the cladding and core layers, respectively.

9. The scintillation optical fiber performance testing method according to claim 7, characterized in that: The method of testing the bending loss of the scintillation optical fiber based on the SiPM test module specifically includes: The length of use is Straight fiber time Test within, get time The total charge detected by the internal SiPM test module ; Place the scintillating fiber in grooves with different curvature radii and bend them at different angles , use the second collimator to direct the high-energy particle radiation beam to one end of the scintillating fiber, and use the SiPM test module to test and obtain the time The total charge detected by the internal SiPM test module ; Using formula Calculate the bending loss rate of different curvature radii under unit angle , which is used to characterize the bending loss of scintillating optical fibers at different curvature radii.

10. The scintillation optical fiber performance testing method according to claim 3, characterized in that: The attenuation time of the scintillation optical fiber is tested based on the attenuation time test module, specifically comprising: The high-energy particle radiation beam emitted by the second radiation source is directed to a point on the scintillating optical fiber by using a third collimator, which is called a radioluminescent point; The optical signal generated at the radioluminescent point is transmitted to the fourth SiPM through the optical fiber, and the optical signal is converted into an electrical signal by the fourth SiPM and then output to the fourth pre-amplifier; The fourth pre-amplifier is used to amplify the electrical signal from the fourth SiPM and perform current-voltage signal conversion, and also has a signal polarity reversal function; The oscilloscope is used to display the electrical signal converted by the fourth pre-amplifier as a curve of signal amplitude changing with time; Computers are used to apply the formula Fitting signal amplitude Over time The decay constant is calculated from the curve of , used to characterize the decay time of scintillation fiber; is the correction constant for the fitting curve; is the correction coefficient of the fitting curve.

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