A calibration method for superconducting dynamic inductance X-ray detector

Abstract

The present application discloses a calibration method for a superconducting dynamic inductance X-ray detector, the method comprising: using a vector network analyzer to calibrate the resonant frequency at the resonant peak of each resonator in the detector, and generating a microwave signal according to the resonant frequency; when the X-ray light source is turned on, using the microwave signal to calibrate the characteristic parameters of the X-ray response corresponding to each resonator. The present application solves the technical problem that the X-ray response performance of the detector cannot be quickly calibrated in the prior art.

Description

Technical Field

[0001] The present application relates to the technical field of device calibration, and in particular to a calibration method for a superconducting dynamic inductance X-ray detector. Background Art

[0002] As a short-wave electromagnetic wave, high-precision detection of X-rays has broad application prospects in the fields of material structure analysis, pulsar space observation, security inspection, etc. Compared with other types of X-ray single-photon detectors, superconducting X-ray single-photon detectors have better energy resolution and detection sensitivity, which is critical for some ultra-fine and extreme conditions applications, and has become a research hotspot for X-ray single-photon detection in recent years.

[0003] Kinetic inductance detectors (KIDs) are a relatively new type of quasi-particle single-photon detectors. A large number of basic and applied researches have been carried out in the microwave and visible light bands. In the X-ray band, recent studies have used thermal kinetic inductance detectors (TKIDs) with absorbers to achieve large-area detection with high energy resolution. However, the frequency division multiplexing circuit test equipment of the detector is numerous and the system construction is complex. How to use a simple method to achieve rapid calibration of the X-ray response performance of the prepared device has great practical value for the preliminary screening of qualified devices and the extraction of characteristic parameters. Summary of the invention

[0004] The technical problem solved by the present application is: in view of the fact that the prior art cannot quickly calibrate the X-ray response performance of the detector, the present application provides a calibration method for a superconducting dynamic inductance X-ray detector. In the scheme provided in the embodiment of the present application, the detector calibration scheme is simple and convenient, and provides an effective way to quickly screen out qualified superconducting dynamic inductance X-ray detectors and preliminarily obtain characteristic parameters such as detector position resolution and response time. It has strong practicality and can be extended to other frequency division multiplexing-based detector screening and calibration.

[0005] In a first aspect, an embodiment of the present application provides a calibration method for a superconducting dynamic inductance X-ray detector, the method comprising: using a vector network analyzer to calibrate the resonant frequency at the resonant peak of each resonator in the detector, and generating a microwave signal based on the resonant frequency; when the X-ray light source is turned on, using the microwave signal to calibrate the characteristic parameters of the X-ray response corresponding to each resonator.

[0006] Optionally, a vector network analyzer is used to calibrate the resonant frequency at the resonant peak of each resonator in the detector, including: setting an initial frequency sweep range of the vector network analyzer, performing preliminary calibration within the initial frequency sweep range using the vector network analyzer to obtain a frequency sweep range after preliminary calibration; and performing fine calibration within the frequency sweep range after preliminary calibration using the vector network analyzer to obtain the resonant frequency at the resonant peak of each resonator.

[0007] Optionally, the initial frequency sweep range is (9kHz~8.5GHz).

[0008] Optionally, calibrating characteristic parameters of the X-ray response corresponding to each resonator using the microwave signal includes:

[0009] Using a power divider to divide the microwave signal into a first signal and a second signal, using the second signal as an excitation signal of the detector and obtaining an output signal under the interference of resonance peaks;

[0010] Inputting the first signal and the output signal of the detector to the L end and the R end of the IQ mixer respectively, and collecting the signals at the I end and the Q end of the IQ mixer using an oscilloscope to obtain the X-ray response signal corresponding to each resonator;

[0011] The X-ray response signal is used to calibrate characteristic parameters of the X-ray response corresponding to each resonator.

[0012] Optionally, before the first signal and the output signal of the detector are respectively input to the L end and the R end of the IQ mixer, the method further includes:

[0013] The output signal is amplified by an amplifier to obtain an amplified signal.

[0014] Optionally, using the pulse signal to calibrate characteristic parameters of the X-ray response corresponding to each resonator includes:

[0015] The X-ray response signal is used to determine the amplitude and time of the pulse, the position resolution of the resonator is determined based on the amplitude, and the response time of the resonator is determined based on the time.

[0016] Compared with the prior art, this application has at least the following beneficial effects:

[0017] In the solution provided in the embodiment of the present application, a vector network analyzer is used to calibrate the resonant frequency at the resonant peak of each resonator in the detector, and a microwave signal is generated according to the resonant frequency; when the X-ray light source is turned on, the microwave signal is used to calibrate the characteristic parameters of the X-ray response corresponding to each resonator. Compared with the traditional frequency division multiplexing readout method, this detector calibration solution is simple and convenient, and provides an effective way to quickly screen out qualified superconducting dynamic inductance X-ray detectors and preliminarily obtain characteristic parameters such as detector position resolution and response time. It has strong practicality and can be extended to other frequency division multiplexing-based detector screening and calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a calibration system for a superconducting dynamic inductance X-ray detector provided in an embodiment of the present application;

[0019] Figure 2 A schematic diagram of simulation results of S parameters corresponding to a resonator in a detector electromagnetic field simulation model based on Zealand IE3D provided in an embodiment of the present application;

[0020] Figure 3 A schematic diagram of a system connection for calibrating the resonant frequency of each resonator provided in an embodiment of the present application;

[0021] Figure 4 A schematic diagram of system connection for calibrating characteristic parameters of X-ray response corresponding to each resonator provided in an embodiment of the present application;

[0022] Figure 5 A signal schematic diagram of an X-ray response provided in an embodiment of the present application;

[0023] Figure 6 A schematic flow chart of a calibration method for a superconducting dynamic inductance X-ray detector provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to better understand the above technical scheme, the technical scheme of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical scheme of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0025] See also Figure 1 , is a schematic diagram of the structure of a calibration system for a superconducting dynamic inductance X-ray detector provided in an embodiment of the present application. Figure 1 The system includes: a vector network analyzer, a detector, an IQ mixer, an amplifier and an oscilloscope.

[0026] Specifically, the superconducting dynamic inductance X-ray detector (hereinafter referred to as the detector) mentioned in the solution provided in the embodiment of the present application is composed of a plurality of resonator arrays, each resonator includes an electrical circuit composed of interdigital capacitors and zigzag inductors connected end to end, and the resonant frequency of each resonator is adjusted by changing the length of the interdigital capacitors.

[0027] The expression for the resonant frequency is:

[0028]

[0029] Among them, L m is the magnetic inductance of the zigzag inductance; L k is the dynamic inductance; C is the capacitance value of the interdigital capacitor.

[0030] For example, see Figure 1 , is a schematic diagram of the structure of a detector electromagnetic field simulation model based on Zealand IE3D provided in an embodiment of the present application, Figure 1 In the simulation model, area 1 is the area with superconducting film, area 2 is the area exposed after etching the superconducting film, port 1 and port 2 are two microwave output ports, 3, 4, 5, 6 represent the meandering inductor, interdigital capacitor, feeder and ground plane respectively. In this simulation model, both port 1 and port 2 are set to 50Ω impedance matching, the sweep frequency range is 9kHz~8.5GHz, and the resonant frequency range of the resonator is between 5~6GHz. For details, see Figure 2 The electromagnetic field simulation result of the S21 parameter corresponding to a resonator in the electromagnetic field simulation model of a detector based on Zealand IE3D provided in the embodiment of the present application can be used to iteratively optimize the chip structure design of the detector through simulation analysis. As an example, in the solution provided in the embodiment of the present application, a Keysight E5071C vector network analyzer with a sweep frequency range covering 9kHz to 8.5GHz can be selected according to the simulation results.

[0031] Further, in the solution provided in the embodiment of the present application, in order to calibrate the detector, it is first necessary to calibrate the resonant frequency of each resonator in the detector by a vector network analyzer. For ease of understanding, the process of calibrating the resonant frequency of each resonator is briefly introduced below.

[0032] See also Figure 3, the vector network analyzer is connected to the detector. When the X-ray light source is not turned on, the mode (Measurement) of the vector network analyzer is set to the dual-port (S21 or S12) scanning mode; because too high power may damage the resonator, and too low power may deteriorate the signal-to-noise ratio of the resonance peak, the power in "Sweep" is set to 5dbm through repeated debugging; the number of scanning points is set to a maximum of 10001 to obtain a more detailed resonance curve; "IF Bandwidth" is set to 70kHz; when performing preliminary calibration of the resonance peak range, "Scale" is set to Auto Scale, and when performing fine calibration of the resonance peak position, "Scale" is set to Scale, and Division, Scale / Div and Reference Position are adjusted according to the width and depth of each resonance peak, in order to obtain the most detailed resonance peak; "Format" is set to Log Mag; connect the Port1 port of the vector network analyzer to the interface 1 of the dynamic inductance detector through a low-loss coaxial line with 50Ω impedance matching, which serves as the RF excitation source of the detector resonator; the Port2 port is also connected to the interface 2 of the dynamic inductance detector through a low-loss coaxial line with 50Ω impedance matching to read the output signal passing through the detector resonator. During the preliminary calibration, set the sweep range of "Stimulus" to the full spectrum range (9kHz~8.5GHz), test and obtain the S21 parameter curve of the detector device, record the resonant frequency range where the resonant peak is located, and set the fine scanning frequency range of each resonator according to the resonant frequency range; gradually narrow the sweep range, and synchronously adjust the "Scale" to scan in turn to obtain the resonant frequency at the resonant peak of each resonator, and use the resonant frequency as the excitation frequency for the next step of X-ray response calibration. It should be understood that in Figure 3 Here, the KID chip refers to the Kinetic inductance detector (KID) chip mentioned in the embodiments of the present application.

[0033] Further, in the solution provided in the embodiment of the present application, after the resonant frequency of each resonator in the detector is calibrated by the vector network analyzer, the characteristic parameters of the X-ray response corresponding to each resonator need to be calibrated using the calibration signal (microwave signal) of the X-ray response when the X-ray light source is turned on. For ease of understanding, the process of calibrating the characteristic parameters of the X-ray response corresponding to each resonator is briefly introduced below.

[0034] See also Figure 4 , is a schematic diagram of a system connection for calibrating characteristic parameters of the X-ray response corresponding to each resonator provided in an embodiment of the present application. Figure 3In the method, a port of a vector network analyzer is connected to an input end of a power divider; an output port of the power divider is connected to a detector, and another output port is connected to an L end of an IQ mixer; an X-ray light source is turned on to irradiate a KID chip in the detector and output a signal, and an amplified signal is obtained by amplifying the output signal through an amplifier, and the amplified signal is input to an R end of the IQ mixer, and a real part I end and an imaginary part Q end of the signal after frequency domain signal processing by the IQ mixer are respectively connected to an oscilloscope through a low-loss coaxial line with 50Ω impedance matching, and the oscilloscope is used to collect signals at the I end and the Q end of the IQ mixer to obtain an X-ray response signal corresponding to each resonator, and the X-ray response signal is used to calibrate the characteristic parameters of the X-ray response corresponding to each resonator.

[0035] Further, in Figure 4In the , change the vector network analyzer "Measurement" to single-port output mode (set to S12 or S11 when outputting from Port1, and set to S21 or S22 when outputting from Port2); set the power in "Sweep" to 5dbm (too high power may damage the resonant device, and too low power may not trigger the IQ mixer to produce nonlinear mixing characteristics); set "IF Bandwidth" to 70kHz. Set the vector network analyzer output frequency to set the "Span" intermediate frequency bandwidth to 0, and set the "Start" starting frequency to the peak resonant frequency. For example, pixel 1 (a resonator in the detector) is 5.467GHz, and pixel 2 (another resonator in the detector that is different from pixel 1) is 5.709GHz. The rest of the settings of the vector network analyzer are the same as those in the above process of calibrating the resonant frequency at the resonance peak of each resonator. During the calibration process, the vector network analyzer will output a microwave signal of specific power and frequency through a power divider, one of which is used as the excitation signal of the detector and the other is input to the L end of the IQ mixer. After passing through the resonator, the excitation signal of the specific frequency will interfere with the resonance peak of the specific frequency to obtain an output signal, which is then input to the amplifier. The voltage source switch of the amplifier is turned on, and the output constant bias of 15V is set to obtain the amplified signal, which is then input to the R end of the IQ mixer. The IQ mixer performs frequency domain signal processing on the input L and R ends to obtain the real part I end and the imaginary part Q end of the signal. The I port and Q port of the IQ mixer are connected to an oscilloscope, and the changes in the oscilloscope waveform can be collected to characterize the information of the incident X-rays. When an X-ray photon is incident, set the "Triger" to the rising edge trigger, adjust the Triger level until the X-ray response signal is collected, and record the pulse profile of the response signal. The oscilloscope waveform changes from smooth and non-fluctuating to outputting pulse signals. The amplitude and time of the pulse represent the energy and position information of the incident X-ray, respectively. The characteristic parameters of each resonator are calibrated according to the amplitude and time of the pulse. Figure 5 As shown, the response time and voltage amplitude of the response signal corresponding to each resonator are extracted as characteristic parameters of the X-ray response corresponding to the resonator. For example, the response time of pixel 1 in the detector is 500ns, and the voltage amplitude is 460mV; the response time of pixel 2 is 230ns, and the voltage amplitude is 650mV.

[0036] Furthermore, after determining the X-ray response characteristics of each resonator, the "bad points" of the dynamic inductance detector can be preliminarily screened out according to the X-ray response characteristics of each resonator, thereby providing a reference for subsequent large-array applications such as X-ray imaging. The X-ray response oscilloscope waveform of each resonator obtained by testing can provide characteristic parameters such as position resolution and response time of each pixel. The above calibration results also provide guidance for further optimization of detector parameter design for specific applications.

[0037] The following is a further detailed description of a calibration method for a superconducting dynamic inductance X-ray detector provided in an embodiment of the present application in conjunction with the accompanying drawings. The specific implementation of the method may include the following steps (the method flow is as follows: Figure 6 shown):

[0038] Step 601: calibrate the resonance frequency of each resonator at the resonance peak in the detector using a vector network analyzer, and generate a microwave signal according to the resonance frequency.

[0039] Step 602: When the X-ray light source is turned on, the characteristic parameters of the X-ray response corresponding to each resonator are calibrated using the microwave signal.

[0040] In one possible implementation, a vector network analyzer is used to calibrate the resonant frequency at the resonant peak of each resonator in the detector, including: setting an initial frequency sweep range of the vector network analyzer, performing preliminary calibration within the initial frequency sweep range using the vector network analyzer to obtain a frequency sweep range after preliminary calibration; and performing fine calibration within the frequency sweep range after preliminary calibration using the vector network analyzer to obtain the resonant frequency at the resonant peak of each resonator.

[0041] In a possible implementation, the initial frequency sweep range is (9 kHz to 8.5 GHz).

[0042] In one possible implementation, the microwave signal is used to calibrate the characteristic parameters of the X-ray response corresponding to each resonator, including: using a power divider to divide the microwave signal into a first signal and a second signal, using the second signal as an excitation signal of the detector and obtaining an output signal under the interference of the resonance peak; inputting the first signal and the output signal of the detector to the L end and R end of the IQ mixer respectively, using an oscilloscope to collect the signals at the I end and Q end of the IQ mixer to obtain the X-ray response signal corresponding to each resonator; and using the X-ray response signal to calibrate the characteristic parameters of the X-ray response corresponding to each resonator.

[0043] In a possible implementation, before the first signal and the output signal of the detector are respectively inputted to the L end and the R end of the IQ mixer, the method further includes: amplifying the output signal by using an amplifier to obtain an amplified signal.

[0044] In one possible implementation, the pulse signal is used to calibrate characteristic parameters of the X-ray response corresponding to each resonator, including: using the X-ray response signal to determine the amplitude and time of the pulse, determining the position resolution of the resonator based on the amplitude, and determining the response time of the resonator based on the time.

[0045] Specifically, in the solution provided in the embodiment of the present application, the process of the calibration method of the above-mentioned large-array superconducting dynamic inductance X-ray single-photon detector has been introduced in the calibration system part of the large-array superconducting dynamic inductance X-ray single-photon detector, and will not be repeated here.

[0046] In the solution provided in the embodiment of the present application, a vector network analyzer is used to calibrate the resonant frequency at the resonant peak of each resonator in the detector, and a microwave signal is generated according to the resonant frequency; when the X-ray light source is turned on, the microwave signal is used to calibrate the characteristic parameters of the X-ray response corresponding to each resonator. Compared with the traditional frequency division multiplexing readout method, this detector calibration solution is simple and convenient, and provides an effective way to quickly screen out qualified superconducting dynamic inductance X-ray detectors and preliminarily obtain characteristic parameters such as detector position resolution and response time. It has strong practicality and can be extended to other frequency division multiplexing-based detector screening and calibration.

[0047] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

[0048] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A calibration method for a superconducting dynamic inductance X-ray detector, characterized in that: include: Using a vector network analyzer to calibrate the resonant frequency at the resonant peak of each resonator in the detector, and generating a microwave signal according to the resonant frequency; When the X-ray light source is turned on, the characteristic parameters of the X-ray response corresponding to each resonator are calibrated using the microwave signal; Using the microwave signal to calibrate characteristic parameters of the X-ray response corresponding to each resonator includes: Using a power divider to divide the microwave signal into a first signal and a second signal, using the second signal as an excitation signal of the detector and obtaining an output signal under the interference of resonance peaks; Inputting the first signal and the output signal of the detector to the L end and the R end of the IQ mixer respectively, and collecting the signals at the I end and the Q end of the IQ mixer using an oscilloscope to obtain the X-ray response signal corresponding to each resonator; The X-ray response signal is used to calibrate characteristic parameters of the X-ray response corresponding to each resonator.

2. The method according to claim 1, characterized in that The resonant frequency of each resonator in the detector is calibrated using a vector network analyzer, including: Setting an initial frequency sweep range of the vector network analyzer, and performing a preliminary calibration within the initial frequency sweep range using the vector network analyzer to obtain a frequency sweep range after preliminary calibration; A vector network analyzer is used to perform fine calibration within the sweep frequency range after the preliminary calibration to obtain the resonant frequency at the resonance peak of each resonator.

3. The method according to claim 2, characterized in that The initial frequency sweep range is 9 kHz to 8.5 GHz.

4. The method according to claim 1, characterized in that Before the first signal and the output signal of the detector are respectively input to the L end and the R end of the IQ mixer, the method further comprises: The output signal is amplified by an amplifier to obtain an amplified signal.

5. The method according to claim 4, characterized in that Using the X-ray response signal to calibrate characteristic parameters of the X-ray response corresponding to each resonator includes: The X-ray response signal is used to determine the amplitude and time of the pulse, the position resolution of the resonator is determined based on the amplitude, and the response time of the resonator is determined based on the time.

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