Synchrotron radiation X-ray pulse time width measuring device

Abstract

The invention relates to a synchrotron radiation X-ray pulse time width measuring device, which comprises a main clock, a time synchronization control device, an X-ray streak camera and an upper computer, and is characterized in that the main clock is used for providing a time reference for a synchrotron radiation light source, the time synchronization control device is connected with the main clock, and the X-ray streak camera is connected with the time synchronization control device; the upper computer is respectively connected with the time synchronization control equipment and the X-ray streak camera; the upper computer is used for enabling the time synchronization control equipment to transmit a trigger signal to the X-ray streak camera according to the time reference of the main clock, and a preset time delay exists between the trigger signal and the time reference of the main clock; the X-ray streak camera is used for receiving the X-ray pulse generated by the synchrotron radiation light source and collecting and outputting an X-ray pulse image under the triggering of the triggering signal; the X-ray pulse image is transmitted to an upper computer, so that the upper computer obtains the time width of the X-ray pulse according to the X-ray pulse image.

Description

Technical Field

[0001] The present invention relates to the technical field of synchrotron radiation light sources, and more specifically to a synchrotron radiation X-ray pulse time width measuring device. Background Art

[0002] Synchrotron radiation is an X-ray source that provides high brightness, wide spectrum and short pulses. It is widely used in cutting-edge fields such as materials science, life science and ultrafast dynamics. A notable feature of synchrotron radiation X-rays is that their pulses have an extremely short time width, usually reaching the picosecond or even sub-picosecond level, which gives it a unique advantage in studying ultrafast processes, chemical reaction dynamics and ultrafast biological imaging.

[0003] However, despite these advantages, when completing experiments such as laser pumping and X-ray single pulse imaging, synchrotron radiation sources need to adopt a mixed electron bunch injection mode, in which only a single large electron bunch can be used for the experiment without affecting other experiments. The X-ray pulses produced by a single electron bunch have a low optical density and a weak signal, especially when measuring extremely short pulse widths, when the number of photons is limited, which increases the difficulty of detection. For example, the Shanghai Light Source (SSRF) storage ring is 432 meters long, and the time it takes for a large electron bunch to rotate around the synchrotron radiation storage ring is about 1.44 microseconds, while the theoretical width of an electron bunch pulse is only 80 picoseconds. The precise positioning of narrow pulses with relatively long rotation times also increases the difficulty of detection.

[0004] At present, commonly used X-ray pulse measurement equipment includes those based on photodiodes, gas ionization chambers, and streak cameras. However, these devices often find it difficult to achieve sufficient signal strength while ensuring time resolution when faced with low X-ray light density, weak pulses, and difficulty in signal positioning in synchrotron radiation sources. For example, photodiodes have difficulty achieving high-sensitivity detection under low light density conditions, and gas ionization chambers have difficulty resolving signal time scales under ultra-narrow pulse widths. Although streak cameras have high time resolution characteristics, when using streak cameras to collect low signal-to-noise ratio signals, the measurement accuracy is greatly affected by noise, making it difficult to collect signals of sufficient intensity while ensuring time resolution. Summary of the invention

[0005] The object of the present invention is to provide a synchrotron radiation X-ray pulse time width measurement device, so as to collect sufficient signals while ensuring the time resolution, and realize the measurement of the time width of the X-ray pulse in the picosecond level.

[0006] Based on the above purpose, the present invention provides a synchrotron radiation X-ray pulse time width measurement device, comprising a master clock, a time synchronization control device, an X-ray streak camera and a host computer, wherein the master clock is used to provide a time reference for a synchrotron radiation light source, the time synchronization control device is connected to the master clock, the X-ray streak camera is connected to the time synchronization control device, and the host computer is connected to the time synchronization control device and the X-ray streak camera, respectively; the host computer is used to enable the time synchronization control device to transmit a trigger signal to the X-ray streak camera according to the time reference of the master clock, and there is a preset delay between the trigger signal and the time reference of the master clock; the X-ray streak camera is used to receive the X-ray pulse generated by the synchrotron radiation light source, and collect and output the X-ray pulse image under the triggering of the trigger signal; the X-ray pulse image is transmitted to the host computer, so that the host computer obtains the time width of the X-ray pulse according to the X-ray pulse image.

[0007] Furthermore, the X-ray streak camera includes a light-carding slit, a photocathode, a photoanode, a scanning device, a signal enhancement device, a fluorescent screen and a camera device, which are arranged in sequence along the X-ray transmission direction. The photocathode is used to produce photoelectrons by photoelectric effect with X-ray pulses, the photoanode is used to accelerate the photoelectrons, the scanning device is used to deflect the photoelectrons to different degrees at different times, the fluorescent screen is used to make the photoelectrons that hit it emit light, and the camera is used to capture an image of the fluorescent screen.

[0008] Furthermore, the trigger signal includes a first trigger signal, a second trigger signal and a third trigger signal, the first trigger signal is used to be transmitted to the scanning device to enable the scanning device to start working; the second trigger signal is used to be transmitted to the signal enhancement device to enable the signal enhancement device to start working; the third trigger signal is used to be transmitted to the camera device to enable the camera device to start taking pictures.

[0009] Further, the delay of the first trigger signal relative to the time base of the master clock is smaller than the delay of the second trigger signal relative to the time base of the master clock, and the delay of the third trigger signal relative to the time base of the master clock is smaller than the delay of the third trigger signal relative to the time base of the master clock.

[0010] Furthermore, the imaging device is configured to capture multiple images within a preset integration time, wherein each image includes multiple pixel points, and the X-ray streak camera also includes a data processing module, which is configured to average the pixel values ​​of each pixel point in each image as the pixel value of the pixel point in the new image; and is configured to send the new image to the host computer as an X-ray pulse image output by the X-ray streak camera.

[0011] Furthermore, the X-ray pulse image contains spatial width information of the X-ray pulse, and the host computer is used to determine the temporal width of the X-ray pulse according to the spatial width information of the X-ray pulse.

[0012] Furthermore, the signal enhancement device includes a first microchannel plate and a second microchannel plate sequentially arranged along the X-ray transmission direction, the first microchannel plate is used to preliminarily amplify the photoelectron signal, and the second microchannel plate is used to further amplify the photoelectron signal.

[0013] Furthermore, the master clock includes an AC power supply, a radio frequency signal source, a first timing event generator and a first timing signal repeater, the AC power supply and the radio frequency signal source are respectively connected to the first timing event generator, the first timing event generator is connected to the first timing signal repeater, and the first timing signal repeater is connected to the time synchronization control device.

[0014] Furthermore, the time synchronization control device includes a second timing signal repeater, a first signal generating device, a second signal generating device and a third signal generating device, the first signal generating device, the second signal generating device and the third signal generating device are respectively connected to the second timing signal repeater, and the second timing signal repeater is connected to the first timing signal repeater; the first signal generating device is used to generate a first trigger signal, the second signal generating device is used to generate a second trigger signal, and the third signal generating device is used to generate a third trigger signal.

[0015] Further, the first signal generating device comprises a second timing event generator, a first timing event receiver and a first photoelectric converter connected in sequence, the second timing event generator is connected to the second timing signal repeater, and the first photoelectric converter is connected to the scanning device; The second signal generating device comprises a third timing event generator, a second timing event receiver and a second photoelectric converter connected in sequence, the third timing event generator is connected to the second timing signal repeater, and the second photoelectric converter is connected to the signal enhancing device; The third signal generating device includes a fourth timing event generator, a third timing event receiver and a third photoelectric converter which are connected in sequence. The fourth timing event generator is connected to the second timing signal repeater, and the third photoelectric converter is connected to the camera device.

[0016] The synchrotron radiation X-ray pulse time width measurement device of the present invention is synchronized with the main clock through a time synchronization control device, and outputs a trigger signal for triggering an X-ray streak camera, thereby realizing X-ray pulse time width measurement with picosecond accuracy; the X-ray pulse image output by the X-ray streak camera is obtained by integrating pulse images collected multiple times within a preset time, thereby improving the signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 2 is a schematic diagram of the structure of a synchrotron radiation X-ray pulse time width measurement device according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of an X-ray streak camera according to an embodiment of the present invention; Figure 3 is a structural schematic diagram of a signal enhancement device according to an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a master clock and a time synchronization control device according to an embodiment of the present invention; Figure 5 An image of an X-ray pulse in time converted from an image of an X-ray pulse in space generated by a large electron bunch obtained by an X-ray streak camera according to an embodiment of the present invention within a 600 picosecond scanning range; Figure 6 This is an X-ray pulse time distribution diagram obtained by sequentially performing 10-picosecond time-delay acquisition on X-ray pulses generated by a large electron bunch using an X-ray streak camera according to an embodiment of the present invention and extracting the X-ray pulses therefrom for Gaussian fitting. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0019] like Figure 1As shown, the synchrotron radiation X-ray pulse time width measuring device of the embodiment of the present invention is used to measure the time width of the X-ray pulse of the synchrotron radiation light source 100, and includes a master clock 200, a time synchronization control device 300, an X-ray streak camera 400 and a host computer 500. The master clock 200 is used to provide a stable and accurate time reference for the synchrotron radiation light source 100, and can synchronize the operations of the components of the synchrotron radiation light source 100 by distributing its time signal; the time synchronization control device 300 is connected to the master clock 200 and is in the same clock network with the master clock 200, the X-ray streak camera 400 is connected to the time synchronization control device 300, and the host computer 500 is respectively connected to the time synchronization control device 300 and the X-ray streak camera 400, and the host computer 500 is used to The time synchronization control device 300 is used to generate a trigger signal according to the time reference of the master clock 200, and the time synchronization control device 300 transmits the trigger signal to the X-ray streak camera 400, wherein there is a preset delay between the trigger signal and the time reference of the master clock 200 (that is, the trigger signal is generated after the preset delay from the time reference of the master clock 200); the X-ray streak camera 400 is used to receive the X-ray pulse generated by the synchrotron radiation light source 100, and to collect the X-ray pulse image under the triggering of the trigger signal, wherein the X-ray pulse image includes the time width information of the X-ray pulse, and the X-ray streak camera 400 will transmit the X-ray pulse image to the host computer 500 after collecting it; the host computer 500 is used to obtain the time width of the X-ray pulse according to the X-ray pulse image.

[0020] like Figure 2As shown, in some embodiments, the X-ray streak camera 400 includes a light-carding slit 410, a photocathode 420, a photoanode 430, a scanning device 440, a signal enhancement device 450, a fluorescent screen 460 and a camera 470, which are sequentially arranged along the X-ray transmission direction. The light-carding slit 410 is used to reduce the area of ​​the incident X-ray to prevent the camera 470 from being overexposed. The photocathode 420 is used to produce photoelectrons by a photoelectric effect with the X-rays. Gold material can be selected as the cathode so that it has a higher photoelectric conversion efficiency within the X-ray energy range of 5KeV-30KeV; the photoanode 430 is used to accelerate the photoelectrons generated at the photocathode 420, and the scanning device 440 is used to form a changing electric field according to a changing scanning voltage. When the photoelectrons pass through the scanning device 440, the changing electric field will cause them to be deflected. When the photoelectrons pass through the scanning device 440 at different times, due to the different electric fields, the photoelectrons will be deflected to different degrees, thereby The time information of the photoelectron is converted into spatial information. For example, the scanning device 440 can generate a linearly enhanced electric field by a voltage that increases linearly with time. In this way, the photoelectrons that pass through the scanning device 440 later will deviate further, so that the photoelectrons that pass through the scanning device 440 at different times will hit different positions of the fluorescent screen 460; the signal enhancement device 450 is used to amplify the input photoelectrons, increase the signal strength, and improve the signal-to-noise ratio. After the photoelectrons pass through the scanning device 440 and the signal enhancement device 450 in sequence, they will hit the fluorescent screen 460 and emit light. The camera device 470 is used to capture the image of the fluorescent screen 460. Since the photoelectrons at different times will undergo different degrees of deflection when passing through the scanning device 440, their positions on the fluorescent screen 460 are also different, that is, the spatial positions of the photoelectrons at different times on the X-ray pulse image are also different. The time interval between the two photoelectrons can be obtained by the spatial distance between any two photoelectrons on the image. The scanning device 440 may have multiple scanning gears, and the scanning voltage corresponding to each scanning gear changes at a different speed over time, and the corresponding scanning range (i.e., the time range of photoelectrons that can be displayed on the image of the camera device 470) is also different. The host computer 500 is configured to control the scanning gear of the scanning device 440, that is, during measurement, the required scanning gear can be set on the host computer 500, and then the host computer 500 can make the scanning device 400 work at the scanning gear, so as to obtain the image of the photoelectrons hitting the fluorescent screen 460 within the time corresponding to the scanning gear.

[0021] In some embodiments, the time synchronization control device 300 may include three channels, each of which may generate a trigger signal, namely a first trigger signal S1, a second trigger signal S2 and a third trigger signal S3, that is, the trigger signal includes a first trigger signal S1, a second trigger signal S2 and a third trigger signal S3, the first trigger signal S1 is used to be transmitted to the scanning device 440, and the scanning device 440 is used to start working after receiving the first trigger signal S1 (that is, to generate a changing electric field to deflect the photoelectrons), the second trigger signal S2 is used to be transmitted to the signal enhancement device 450, and the signal enhancement device 450 starts working after receiving the second trigger signal S2 (that is, to amplify the photoelectron signal), and the third trigger signal S3 is used to be transmitted to the camera device 470, and the camera device 470 takes a picture of the fluorescent screen 460 after receiving the third trigger signal S3 to obtain an X-ray pulse image; after taking the picture, the camera device 470 will transmit the image to the host computer 500, and the host computer 500 will determine the time width of the X-ray pulse according to the image.

[0022] During measurement, it is usually expected that the scanning device 440 starts working when the photoelectron is transmitted to the scanning device 440, and the signal enhancing device 450 starts working after the photoelectron is transmitted to the signal enhancing device 450, and the camera device 470 takes a picture of the fluorescent screen 460 after the photoelectron hits the fluorescent screen 460. This can avoid taking pictures of other stray light, thereby reducing noise. Therefore, the delays of the first trigger signal S1, the second trigger signal S2 and the second trigger signal S3 relative to the time base of the main clock 200 are different. The specific delay is related to the time when the first photoelectron generated by the X-ray pulse generated by the electron beam to be measured hits the fluorescent screen 460 and the structural parameters of the X-ray streak camera 400. Specifically, assuming that the time delay of the first photoelectron generated by the X-ray pulse generated by the electron beam to be measured hitting the fluorescent screen 460 relative to the time base of the master clock 200 is T0, that is, taking the time base as the starting point, the first photoelectron hits the fluorescent screen 460 after T0, then the delay of the third trigger signal S3 relative to the time base can be set to T0, the delay of the second trigger signal S2 relative to the time base of the master clock 200 is T0-Δt1, and the delay of the third trigger signal S3 relative to the time base of the master clock 200 is T0-Δt2, where Δt1 and Δt2 are parameters related to the structure of the X-ray streak camera 400, for example, Δt1=Δt2=1 microsecond. Therefore, the delay of the first trigger signal S1 is less than the delay of the second trigger signal S2, and the delay of the third trigger signal S3 is less than the delay of the third trigger signal S3.

[0023] The method for determining T0 in the embodiment of the present invention is as follows: By adjusting the scanning voltage, the X-ray streak camera 400 has the maximum scanning range, that is, the scanning voltage is set to the slowest gear with time, and the time scale of the image presented on the camera device 470 is the maximum gear. For example, the scanning range of the X-ray streak camera 400 can be 4 microseconds, that is, the photoelectrons appearing within 4 microseconds can be displayed on the image it captures. The period of the X-ray pulse generated by the electron bunch to be tested in the synchrotron radiation light source 100 is usually less than the maximum scanning range of the X-ray streak camera 400, for example, 1.44 microseconds. Therefore, when the X-ray streak camera 400 uses the 4 microsecond gear for scanning, at least two X-rays generated by the electron bunch to be tested can be seen. Therefore, at this gear, the image captured by the X-ray streak camera 400 can display all the photoelectrons generated by the X-ray pulse generated by the electron bunch to be tested, and then the rough value of T0 can be estimated based on the image. However, since the pixel of the camera device 470 used in the present invention is 2048x2048 Pixels 2 In the 4 microsecond range, the time width corresponding to a single pixel is about 2ns, which is much larger than the pulse width of the X-ray pulse of the electron bunch to be measured. Therefore, the X-ray pulse of the electron bunch to be measured observed in the maximum scanning range is only a bright spot of one pixel, and the T0 time with an accuracy of 2ns can only be obtained based on this bright spot. Therefore, it is necessary to obtain the delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 respectively according to the rough value of T0, and adjust the scanning range of the X-ray streak camera 400 to be reduced by one level, and take the image under the scanning range after the reduction by one level. If all the photoelectrons of the X-ray pulse are not displayed in the image, it is necessary to adjust the delays of each trigger signal again so that all the photoelectrons of the X-ray pulse can be displayed in the image. If all the photoelectrons of the X-ray pulse can still be displayed in the image, no adjustment is required; a new T0 is obtained according to the image that can display all the photoelectrons of the X-ray pulse, and then a new delay of each trigger signal is set according to the new T0, and then the scanning range of the X-ray streak camera 400 is reduced again, and an image is taken under a smaller scanning range and a new delay of each trigger signal, and an updated T0 value is determined according to the image that can display all the photoelectrons of the X-ray pulse under the smaller scanning range, and then the above operation is repeated, and the T0 value is determined by gradually reducing the scanning range of the X-ray streak camera 400 until the scanning range of the X-ray streak camera 400 is adjusted to the minimum, and the T0 value obtained at this time is the most accurate. For example, the scanning ranges of the X-ray streak camera 400 are 4 microseconds, 20 nanoseconds, 10 nanoseconds, 5 nanoseconds, 2 nanoseconds and 600 picoseconds, from large to small. When determining T0, the scanning range is first set to 4 microseconds to obtain T0 under the scanning range, and then the scanning range is adjusted to 20 nanoseconds to obtain T0 at 20 nanoseconds, and so on, until T0 at 600 microseconds is obtained. At the 600 picosecond level, the accuracy of a single pixel is about 0.3 picoseconds, and T0 at this time is also the required precise value.

[0024] After determining T0, the delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 can be obtained respectively, and then the host computer 500 can obtain the X-ray pulse image output by the X-ray streak camera 400 under the minimum scanning range within a preset time (usually 1 second). According to the image, the spatial distance between the first photon and the last photon of the X-ray pulse of the electron beam to be measured can be calculated, and then their time interval can be determined according to the spatial distance, and the time interval is the time width of the X-ray pulse of the electron beam to be measured.

[0025] Specifically, for any two photons A and B, assuming that the time interval between them is ΔT, when photon A passes through the scanning device 400, its scanning voltage is V A When photon B passes through scanning device 400, its scanning voltage is V B , the spatial interval between photon A and photon B on the fluorescent screen 460 is ΔX, and the conversion relationship between ΔT and ΔX is: ΔX=ΔT×|V A -V B | The frequencies of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 can be set to be the same. Theoretically, it is best to be the same as the frequency of the X-ray pulse. However, considering that too high a frequency may cause the X-ray streak camera 400 to overheat and cause damage, their frequencies can be set to any value below the maximum value that the X-ray streak camera 400 can withstand. The higher their frequency, the more accurate the measurement result.

[0026] In some embodiments, the X-ray streak camera 400 may further include a data processing module (not shown in the figure), which has a multi-shot integration function. Specifically, the camera device 470 can collect data N times within the integration time according to the integration time set by the host computer 500, that is, collect N images, where N is the value obtained by rounding down the product of the integration time and the frequency of the trigger signal; the data processing module averages the pixel values ​​of each pixel point of the image in the N images as the pixel value of the pixel point in the new image, and the new image is the result of multi-shot pulse triggering acquisition integration, and then the new image is sent to the host computer 500 as the X-ray pulse image output by the X-ray streak camera 400, and the host computer 500 calculates the time width of the X-ray pulse based on the new image.

[0027] Since the time synchronization control device 300 can be synchronized with the main clock 200 of the synchrotron radiation light source 100, the output pulse of the time synchronization control device 300 can maintain a fixed delay length, and the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are all provided by the time synchronization control device 300, and thus can maintain their own fixed delay lengths with the X-ray pulses generated by the electron bunch to be measured, so that the X-ray streak camera 300 can collect the same pulse signal multiple times at the same position, thereby making it possible to improve the signal-to-noise ratio by integrating multiple collections.

[0028] In some embodiments, the camera 470 may be a CCD (charge coupled device) camera.

[0029] like Figure 3 As shown, in some embodiments, the signal enhancement device 450 may include a first microchannel plate 451 and a second microchannel plate 452 arranged in sequence, the first microchannel plate 451 is used to preliminarily amplify the photoelectron signal, and its gain coefficient is G1; the second microchannel plate 452 is used to further enhance the photoelectron signal, and its gain coefficient is G2. Assuming that the intensity of the photoelectron signal input to the signal enhancement device 450 is Sin, and the intensity of the photoelectron signal output from the signal enhancement device 450 is Sout, then Sout=Sin×G1×G2.

[0030] like Figure 4 As shown, the master clock 200 may include an AC power supply 210, an RF signal source 220, a first timing event generator 230 and a first timing signal repeater 240. The AC power supply 210 and the RF signal source 220 are respectively connected to the first timing event generator 230, the first timing event generator 230 is connected to the first timing signal repeater 240, and the first timing signal repeater 240 is connected to the time synchronization control device 300; the AC power supply 210 is used for power supply, the RF signal source 220 is used to generate a crystal oscillator clock signal, the first timing event generator 230 is used to generate and distribute various timing signals, the first timing signal repeater 240 is used to distribute the crystal oscillator clock signal to the time synchronization control device 300, and the first timing signal repeater 240 will also distribute the crystal oscillator clock signal to each line station to ensure time synchronization.

[0031] The time synchronization control device 300 may include a second timing signal repeater 310, a first signal generating device 320, a second signal generating device 330 and a third signal generating device 340, the first signal generating device 320, the second signal generating device 330 and the third signal generating device 340 are respectively connected to the second timing signal repeater 310, and the second timing signal repeater 310 is connected to the first timing signal repeater 240; the second timing signal repeater 310 is used to maintain the stability of the timing signal transmitted over long distances, the first signal generating device 320 is used to generate a first trigger signal S1, the second signal generating device 330 is used to generate a second trigger signal S2, and the third signal generating device 340 is used to generate a third trigger signal S3.

[0032] The first signal generating device 320 may include a second timing event generator 321, a first timing event receiver 322 and a first photoelectric converter 323 connected in sequence, the second timing event generator 321 is used to send a new timing signal according to the timing signal sent by the master clock 100, the first timing event receiver 322 is used to receive the timing signal sent by the second timing event generator 321 and send it to the first photoelectric converter 323 after decoding, the first photoelectric converter 323 is used to convert the optical signal into an electrical signal, that is, the first trigger signal S1, the first photoelectric converter 323 is connected to the scanning device 440 to send the first trigger signal S1 to the scanning device 440; the second signal generating device 330 may include a third timing event generator 331, a second timing event receiver 332 and a second photoelectric converter 333 connected in sequence, the third timing event generator 331 is used to send a new timing signal according to the timing signal sent by the master clock 100, the second timing event receiver 332 is used to receive the third timing event The event generator 331 sends out a timing signal and decodes it before sending it to the second photoelectric converter 333. The second photoelectric converter 333 is used to convert an optical signal into an electrical signal, i.e., a second trigger signal S2. The second photoelectric converter 333 is connected to the signal enhancement device 450 to send the second trigger signal S2 to the signal enhancement device 450. The third signal generating device 340 may include a fourth timing event generator 341, a third timing event receiver 342 and a third photoelectric converter 343 connected in sequence. The third timing event generator 341 is used to send a new timing signal according to the timing signal sent by the master clock 100. The third timing event receiver 342 is used to receive the timing signal sent by the fourth timing event generator 341 and decode it before sending it to the third photoelectric converter 343. The third photoelectric converter 343 is used to convert an optical signal into an electrical signal, i.e., a third trigger signal S3. The third photoelectric converter 343 is connected to the camera device 470 to send the third trigger signal S3 to the camera device 470.

[0033] In some embodiments, the host computer 500 may be installed with a first software written in Python language for controlling the state monitoring and parameter setting of the time synchronization control device 300. The first software has a state monitoring module, which can be used to set the time synchronization control device 300 to synchronize with the master clock 200 and detect the synchronization state with the master clock 200. The state monitoring module may also have receiver state monitoring, system-wide enabling state monitoring, and device internal hardware connection state monitoring functions, which facilitates troubleshooting when the device is working abnormally. The host computer 500 may also be installed with a second software for controlling the parameter setting and state monitoring of the X-ray streak camera 400. The second software includes static / dynamic mode switching, scanning range selection, trigger on-off switching, camera state monitoring, camera acquisition parameter setting, image preview and storage and other functions. Among them, the static mode is a single acquisition mode, and the dynamic acquisition is a cyclic acquisition mode. The optional scanning range gears are 600 ps, ​​2 ns, 5 ns, 10 ns, 20 ns, and 4 μs. The trigger on-off switching is a selection between an external trigger source and an internal trigger source. Camera status monitoring includes functions such as scanning circuit bias status monitoring, MCP gain voltage status monitoring, and voltage status monitoring between the photocathode and the anode. Camera acquisition parameter settings include functions such as integration time setting, trigger mode setting, and scanning gear setting. Image preview and storage include display contrast setting, image storage path setting, whether the screen is stored setting, and image preview. The user can operate the high-precision X-ray streak camera 400 and preview and store data acquisition results through the second software of the host computer 500. The first software and the second software are both packaged software, which can be formed into two functional modules after being installed in the host computer 500. Through these two functional modules, the time synchronization control device 300 and the X-ray streak camera 400 can be controlled respectively, thereby achieving high-precision time width measurement.

[0034] Exemplarily, the synchrotron radiation light source 100 may be a synchrotron radiation storage ring, whose circumference is 432 meters. It takes 1.44 microseconds for an electron bunch to go around the storage ring, so the frequency of the electron bunch to generate X-ray pulses is about 694 kHz. In the mixed bunch injection mode, the storage ring has a large electron bunch of 80 picoseconds and 200 small electron bunches of 20 picoseconds. The interval between the large electron bunch and the small electron bunch is 400 nanoseconds, and the interval between the small electron bunches is 3.2 nanoseconds. In experiments, large electron bunches are generally used, so it is necessary to measure the time width of the X-ray pulses generated by the large electron bunches through the measuring device of the present invention. The frequency of the master clock 200 is 500MHz. Considering that the trigger frequency of the X-ray streak camera 400 cannot be too fast, the frequencies of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are all set to 173.5Hz, that is, when the large electron bunch goes around the synchrotron radiation storage ring 4000 times, the X-ray pulse image is collected once by the X-ray streak camera 400. Since the large electron bunch in the synchrotron radiation storage ring is relatively stable on the time scale of picoseconds, for example, usually on the order of 10 picoseconds, the stability of each trigger signal is required to achieve multiple pulse repetition measurement. The maximum clock jitter of the time synchronization control device 300 of the measuring device of the present invention is 3.36 picoseconds, which is less than the time resolution of the X-ray streak camera 400 of 7.3 picoseconds, and is also less than the time width of the large electron bunch of 10 picoseconds, so it can fully meet the picosecond stability requirements of each trigger signal in the measurement of the X-ray pulse time width. That is to say, the accuracy of the time synchronization control device 300 of the present invention can reach the picosecond level, so the synchrotron radiation X-ray pulse time width measurement device of the present invention can achieve picosecond accuracy measurement. The specific experimental measurement results are as follows: like Figure 5 The figure shows an image of an X-ray pulse in time converted from an image of an X-ray pulse in space generated by a large electron bunch obtained by an X-ray streak camera 400 under a scanning range of 600 picoseconds. The width of the white light spot along the ordinate in the figure is the time width of the X-ray pulse. From the results in the figure, it can be seen that the time width of the X-ray pulse is about 80 picoseconds, which is close to the theoretical time width of a large electron bunch. There are also fewer noise points in the figure, which proves that the measurement device of the present invention can effectively improve the signal-to-noise ratio and overcome the problem of low signal-to-noise ratio when using an independent X-ray streak camera to collect single-shot pulses. Figure 6The figure shows the X-ray pulse time distribution diagram obtained by performing four 10-picosecond delay acquisitions at the original position and from the original position in sequence using the X-ray streak camera 400 to extract the X-ray pulses therein for Gaussian fitting, wherein the original position acquisition refers to the acquisition when the delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are T0-2 microseconds, T0-1 microseconds and T0 respectively, and the 10-picosecond delay acquisition refers to performing a 10-picosecond delay on each trigger signal based on the original position, that is, performing one 10-picosecond delay. After the delay, the delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are T0-2 microseconds-10 picoseconds, T0-1 microseconds-10 picoseconds and T0-10 picoseconds respectively. After two 10-picosecond delays, the delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are T0-2 microseconds-20 picoseconds, T0-1 microseconds-20 picoseconds and T0-20 picoseconds respectively. And so on. After four 10-picosecond delays, data after a delay of 10 picoseconds, a delay of 20 picoseconds, a delay of 30 picoseconds and a delay of 40 picoseconds can be obtained. Figure 6 In the figure, the dotted circle marks the original position data, that is, the position collected at the original position, the black square marks the data after a delay of 10 picoseconds, the pentagon marks the data after a delay of 20 picoseconds, the inverted triangle marks the data after a delay of 30 picoseconds, and the left triangle marks the data after a delay of 40 picoseconds. The data above the pulse waveform are used to indicate the pixel point numbers corresponding to the moment corresponding to the pulse peak, which are 56, 72, 88, 113, and 134 respectively. After conversion to time, they are 24.08ps, 30.96ps, 37.845ps, 48.59p, and 57.62ps respectively. The differences are all within the error range, which proves the effectiveness of the time synchronization control device 300 with picosecond accuracy, and further proves that the present invention can be used for synchrotron radiation X-ray pulse time width measurement with picosecond accuracy.

[0035] The method for measuring the pulse time width of synchrotron radiation X-rays using the device for measuring the pulse time width of the synchrotron radiation X-rays according to the embodiment of the present invention comprises the following steps: S10: To prevent abnormalities, a synchronization status monitoring flag is provided in the host computer 500, and the status of the flag is observed to check the synchronization status of the time synchronization control device 300 and the master clock 100; and the repetition frequency of the X-ray pulses in the synchrotron radiation light source 100 is determined at the same time; S20: On the host computer 500, the output frequency and pulse width of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 of the time synchronization control device 300 are set according to the repetition frequency of the X-ray pulse, wherein the output frequency and the pulse width are two independent parameters, and the output frequency is set according to the input frequency division parameter N 分频 Can be set to 125MHz / N分频 , the pulse width is based on the input pulse width parameter N 脉宽 Can be set to 8ns × N 脉宽 , N is required when setting 脉宽 Less than N 分频 ; and the delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are set to 1 microsecond, 2 microseconds and 3 microseconds respectively; S30: setting the scanning range of the X-ray streak camera 400 to the maximum scanning range (for example, 4 microseconds) on the host computer 500, setting the acquisition time of the X-ray streak camera 400 (for example, 1 second), and setting the trigger mode of the X-ray streak camera 400 to external trigger; S40: the scanning range of the X-ray streak camera 400 is adjusted from large to small for multiple times until it is adjusted to a preset scanning range. Each time when the scanning range is adjusted to a certain range, the delay length of each trigger signal is adjusted so that the X-ray pulse of the electron bunch to be measured is displayed in the image collected by the X-ray streak camera to determine T0 under the scanning range; S50: Determine the delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 according to T0 of the X-ray streak camera 400 in a preset scanning range (e.g., 600 picoseconds), for example, set to T0-2 microseconds, T0-1 microseconds and T0 respectively; S60: The X-ray pulse image is collected by the X-ray streak camera 400, and the host computer 500 can determine the time width of the X-ray pulse according to the X-ray pulse image.

[0036] The synchrotron radiation X-ray pulse time width measurement device of the embodiment of the present invention is synchronized with the main clock 200 through the time synchronization control device 300, and outputs a trigger signal for triggering the X-ray streak camera 400, thereby realizing X-ray pulse time width measurement with picosecond accuracy; the X-ray pulse image output by the X-ray streak camera 400 is obtained by integrating the pulse images collected multiple times within a preset time, so the signal-to-noise ratio can be improved.

[0037] The above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various changes can be made to the above embodiments of the present invention. For example, the gold material used in the photocathode of the present invention can be replaced by other materials with higher photoelectric conversion efficiency for X-rays, and the software program in the host computer 500 can also be written in other programming languages ​​besides Python, and the X-ray pulse time width measurement device of the present invention can also be used for the time width measurement of other picosecond X-ray pulse light sources, as long as it has periodicity, can provide time synchronization signals and can be collected by X-ray streak cameras. That is, all simple, equivalent changes and modifications made according to the claims and description of the present invention application fall within the scope of protection of the claims of the patent of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A synchrotron radiation X-ray pulse time width measurement device, characterized in that: It includes a master clock, a time synchronization control device, an X-ray streak camera and a host computer, wherein the master clock is used to provide a time reference for a synchrotron radiation source, the time synchronization control device is connected to the master clock, the X-ray streak camera is connected to the time synchronization control device, and the host computer is connected to the time synchronization control device and the X-ray streak camera respectively; the host computer is used to enable the time synchronization control device to transmit a trigger signal to the X-ray streak camera according to the time reference of the master clock, and there is a preset delay between the trigger signal and the time reference of the master clock; The X-ray streak camera is used to receive the X-ray pulses generated by the synchrotron radiation source, and to collect and output the X-ray pulse images under the triggering of the trigger signal; The X-ray pulse image is transmitted to the host computer, so that the host computer obtains the time width of the X-ray pulse according to the X-ray pulse image.

2. The synchrotron radiation X-ray pulse time width measuring device according to claim 1, characterized in that: The X-ray streak camera includes a light-carding slit, a photocathode, a photoanode, a scanning device, a signal enhancement device, a fluorescent screen and a camera device, which are arranged in sequence along the X-ray transmission direction. The photocathode is used to produce photoelectrons by photoelectric effect with X-ray pulses, the photoanode is used to accelerate the photoelectrons, the scanning device is used to cause the photoelectrons at different times to be deflected to different degrees, the fluorescent screen is used to make the photoelectrons that hit it emit light, and the camera is used to capture an image of the fluorescent screen.

3. The synchrotron radiation X-ray pulse time width measuring device according to claim 2, characterized in that: The trigger signal includes a first trigger signal, a second trigger signal and a third trigger signal. The first trigger signal is used to be transmitted to the scanning device to enable the scanning device to start working; the second trigger signal is used to be transmitted to the signal enhancement device to enable the signal enhancement device to start working; the third trigger signal is used to be transmitted to the camera device to enable the camera device to start taking pictures.

4. The synchrotron radiation X-ray pulse time width measuring device according to claim 3, characterized in that: The delay of the first trigger signal relative to the time base of the master clock is smaller than the delay of the second trigger signal relative to the time base of the master clock, and the delay of the third trigger signal relative to the time base of the master clock is smaller than the delay of the third trigger signal relative to the time base of the master clock.

5. The synchrotron radiation X-ray pulse time width measuring device according to claim 2, characterized in that: The imaging device is configured to collect a plurality of images within a preset integration time, wherein each image includes a plurality of pixels, and the X-ray streak camera further includes a data processing module, wherein the data processing module is configured to average the pixel values ​​of the pixel point of each image as the pixel value of the pixel point of the new image for each pixel point; And it is configured to send the new image to the host computer as the X-ray pulse image output by the X-ray streak camera.

6. The synchrotron radiation X-ray pulse time width measuring device according to claim 2, characterized in that: The X-ray pulse image includes spatial width information of the X-ray pulse, and the host computer is used to determine the temporal width of the X-ray pulse according to the spatial width information of the X-ray pulse.

7. The synchrotron radiation X-ray pulse time width measuring device according to claim 2, characterized in that: The signal enhancement device comprises a first microchannel plate and a second microchannel plate arranged in sequence along the X-ray transmission direction, wherein the first microchannel plate is used for preliminarily amplifying the photoelectron signal, and the second microchannel plate is used for further amplifying the photoelectron signal.

8. The synchrotron radiation X-ray pulse time width measuring device according to claim 2, characterized in that: The master clock includes an AC power supply, a radio frequency signal source, a first timing event generator and a first timing signal repeater. The AC power supply and the radio frequency signal source are respectively connected to the first timing event generator, the first timing event generator is connected to the first timing signal repeater, and the first timing signal repeater is connected to the time synchronization control device.

9. The synchrotron radiation X-ray pulse time width measuring device according to claim 8, characterized in that: The time synchronization control device includes a second timing signal repeater, a first signal generating device, a second signal generating device and a third signal generating device, the first signal generating device, the second signal generating device and the third signal generating device are respectively connected to the second timing signal repeater, and the second timing signal repeater is connected to the first timing signal repeater; the first signal generating device is used to generate a first trigger signal, the second signal generating device is used to generate a second trigger signal, and the third signal generating device is used to generate a third trigger signal.

10. The synchrotron radiation X-ray pulse time width measuring device according to claim 9, characterized in that: The first signal generating device comprises a second timing event generator, a first timing event receiver and a first photoelectric converter connected in sequence, the second timing event generator is connected to the second timing signal repeater, and the first photoelectric converter is connected to the scanning device; The second signal generating device comprises a third timing event generator, a second timing event receiver and a second photoelectric converter connected in sequence, the third timing event generator is connected to the second timing signal repeater, and the second photoelectric converter is connected to the signal enhancing device; The third signal generating device includes a fourth timing event generator, a third timing event receiver and a third photoelectric converter which are connected in sequence. The fourth timing event generator is connected to the second timing signal repeater, and the third photoelectric converter is connected to the camera device.

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