阅读说明：本技术 一种在线式滤片堆栈谱仪 (Online filter stack spectrometer ) 是由 温家星 于明海 曾鸣 马舸 吴玉迟 赵宗清 于 2021-06-23 设计创作，主要内容包括：本发明公开了一种在线式滤片堆栈谱仪,包括依次由至少一个金刚石探测器和多个闪烁体探测器以堆栈方式构成的射线灵敏单元,通过光纤接收射线灵敏单元中的闪烁体探测器产生的可见光信号并转换为电信号的光电转换单元,用于接收射线灵敏单元中的金刚石探测器产生的电流脉冲信号和光电转换单元输出的电信号并处理为数字信号的电子学系统,用于偏转伴随X射线出射的高能电子的偏转磁铁,以及用于对准X射线源的瞄准相机。本发明将射线灵敏单元采用金刚石探测器和闪烁体探测器组合成滤片堆栈方式,结合电子学系统对电信号进行处理和高速采用,实现了对宽能段(10keV～10MeV)、脉冲式X射线源能谱的在线实时测量。(The invention discloses an online filter stack spectrometer which comprises a ray sensitive unit, a photoelectric conversion unit, an electronic system, a deflection magnet and an aiming camera, wherein the ray sensitive unit is sequentially formed by at least one diamond detector and a plurality of scintillator detectors in a stacking mode, the photoelectric conversion unit is used for receiving visible light signals generated by the scintillator detectors in the ray sensitive unit and converting the visible light signals into electric signals through optical fibers, the electronic system is used for receiving current pulse signals generated by the diamond detectors in the ray sensitive unit and the electric signals output by the photoelectric conversion unit and processing the electric signals into digital signals, the deflection magnet is used for deflecting high-energy electrons emitted along with X rays, and the aiming camera is used for aiming at an X-ray source. The invention combines a diamond detector and a scintillator detector into a filter stack mode for a ray sensitive unit, processes electric signals by combining an electronics system and adopts the electric signals at high speed, and realizes the online real-time measurement of the energy spectrum of a wide energy band (10 keV-10 MeV) and a pulse type X-ray source.)

1. An online filter stack spectrometer is characterized by comprising

The radiation sensitive unit is sequentially formed by at least one diamond detector and a plurality of scintillator detectors in a stacking mode and is used for detecting wide-energy-band pulse X-rays, the diamond detector generates a current pulse signal, and the scintillator detectors generate a visible light signal;

the photoelectric conversion unit receives visible light signals generated by a scintillator detector in the ray sensitive unit through an optical fiber and converts the visible light signals into electric signals;

the electronic system is used for receiving and processing a current pulse signal generated by a diamond detector in the ray sensitive unit and an electric signal output by the photoelectric conversion unit into a digital signal so as to solve the energy spectrum of the pulse type X ray in real time according to the signal intensity detected by the ray sensitive unit;

a deflection magnet for deflecting high-energy electrons emitted along with the X-rays; and

and the aiming camera is used for aiming the X-ray source so that X-rays can penetrate through the multi-layer ray sensitive units.

2. The online filter stack spectrometer according to claim 1, characterised in that the photoelectric conversion unit comprises a photodiode or/and a photomultiplier tube.

3. The online filter stack spectrometer according to claim 2, wherein when the photoelectric conversion unit employs a photodiode and a photomultiplier tube, the scintillator detector at the X-ray incident end is connected to the photodiode, and the remaining scintillator detectors are connected to the photomultiplier tube.

4. The online filter stack spectrometer according to claim 1, wherein the electronics system comprises a front-end electronics system, a back-end electronics system and a power system, wherein the front-end electronics system is used for converting the current signals output by the diamond detector and the photoelectric conversion unit into voltage signals and processing the voltage signals to output analog waveform signals, the back-end electronics system adopts a digital acquisition card for digitally sampling, buffering and transmitting the analog waveform signals output by the front-end electronics system, and the power system is used for supplying power to the front-end electronics system, the back-end electronics system, the photoelectric conversion unit and the diamond detector.

5. The online filter stack spectrometer according to claim 4, wherein the front-end electronics system comprises a transimpedance amplifier, a filter shaping circuit, a trigger circuit and a complex programmable logic device, wherein the transimpedance amplifier is used for converting current signals output by the diamond detector and the photoelectric conversion unit into voltage signals, the filter shaping circuit is used for performing amplitude phase adjustment and filtering on the voltage signals output by the transimpedance amplifier, the trigger circuit is used for generating trigger signals of a single channel, and the complex programmable logic device is used for judging the trigger logic and outputting final trigger signals when multiple channels are triggered simultaneously.

6. The online filter stack spectrometer according to claim 5, wherein the trigger circuit employs a hysteresis comparator.

7. The online filter stack spectrometer according to claim 5, wherein the front and back electronics systems are each configured as 16 channels.

8. The online filter stack spectrometer according to any one of claims 1-7, wherein the radiation sensitive unit comprises at least one diamond detector and a plurality of scintillator detectors arranged in a stack in sequence from the incident direction of the X-ray, and a filter interposed between adjacent detectors to attenuate the X-ray, wherein the scintillator thickness of the scintillator detectors is gradually increased.

9. The online filter stack spectrometer according to claim 8, wherein the diamond detector is a thin-sheet diamond detector with a thickness of 50-400 μm.

10. The online filter stack spectrometer according to claim 8, wherein the thickness of the scintillator in the scintillator detector is 5mm to 10 cm.

Technical Field

The invention relates to a spectrometer, in particular to an online filter stack spectrometer.

Background

The high-brightness and ultrashort-pulse X-ray source driven by laser or accelerator has wide application prospect in the fields of nondestructive testing, biomedical imaging, ultrafast micro-process scientific research and the like due to the characteristics of short pulse width, microfocus, wide energy spectrum and the like. The energy spectrum of the X-ray source is one of the most important characteristics of the X-ray source, and has important value for X-ray source application and X-ray source research. The energy spectrum of the X-ray source can cover the range of keV to tens of MeV, and the energy spectrum measurement technology is diversified by combining the characteristics of a pulse radiation field.

The existing energy spectrum measuring techniques are broadly divided into four categories: 1) energy spectrum measurement technology based on single photon counting method. The pixel type semiconductor detector working in a single photon counting mode, such as a single photon CCD, can spatially distinguish single photons, count the energy deposition of a plurality of photons in a semiconductor device, and can accurately obtain an X-ray energy spectrum within the range of 1keV-30 keV. 2) Energy spectrum measurement technology based on a dispersion method. By using the dispersion effect when the X-ray passes through the grating or the crystal, the X-ray with different energy can be diffracted to different angles, and the X-ray energy spectrum with the energy below 100keV can be accurately measured by measuring the X-ray intensity at different angles. 3) Energy spectrum measurement technology based on a filter disc method. The X-ray is attenuated by the filter discs with different thicknesses and materials, the intensity of the attenuated X-ray is detected, and the incident X-ray energy spectrum can be reversely solved through the intensity of the X-ray attenuated by the filter discs with different thicknesses and materials due to different penetrating abilities of the X-ray with different energies. 4) Energy spectrum measurement technology based on Compton effect. The high-energy X-ray can generate Compton scattering with a conversion medium to generate recoil electrons, an electron spectrometer is placed behind the conversion medium to measure the recoil electron energy spectrum, and the recoil electron energy spectrum can be used for deducing the original pulse radiation field energy spectrum.

Energy spectrum measurement technology based on single photon counting method, such as single photon CCD spectrometer. The conventional semiconductor device requires a large number of channels, a single photon counting condition (maximum incidence of 1 photon per unit) is required to be met, and certain statistics (the number of signals recorded to photons is large) is required to be provided. Therefore, the number of detector units is required to be large, the detectors meeting the requirements are generally CCD and CMOS, the method needs to ensure that the energy of single photons is completely deposited in the detectors, Compton scattering or electron escape needs to be avoided, and therefore, only photons with keV-tens of keV can be measured, and the method is difficult to be applied to measurement of energy spectrums with higher energy bands.

Energy spectrum measurement techniques based on dispersion methods, such as curved crystal spectrometers. Mainly depends on the dispersive element, the efficiency is low, and for high-energy X-rays above 100keV, the high-energy X-rays are more granular, and the dispersive element with high efficiency is difficult to obtain, so the dispersive element can not be used for energy spectrum measurement of high-energy X-rays above hundred keV.

The spectrum measurement technique based on the Compton effect has extremely low spectrum efficiency, generally 10, because the Compton effect needs to occur to generate electrons with high energy and collimation on scattered electrons is needed¹⁴The energy spectrum can be obtained only by the photon yield, and the method cannot measure the medium-low energy rays occupying the absolute part in the energy spectrum of the laser X-ray source and only can measure the high-energy gamma rays (1-30 MeV) at the tail part of the energy spectrum.

The most widely applied spectrum measuring technology based on the filter method is a filter stack spectrometer which can measure the spectrum of a wide range of energy bands from tens of keV to tens of MeV. As early as 1999, Nolte et al designed a filter stack spectrometer based on different filters and pyroelectric detectors for measuring the energy spectrum of 10 keV-1 MeV pulsed radiation field photons. In 2008, Chen et al, 2009, Behrens et al, 2015, Jeon et al, 2017, Yu et al, filter stack spectrometers were designed based on imaging plates or pyroelectric detectors, and good experimental results were obtained. However, data reading modes of the imaging plate and the pyroelectric detector are off-line reading, a sensitive medium needs to be taken out of a spectrometer and then data is read by using other equipment, the single measurement data reading step is complicated, the time is usually spent for more than 10 minutes, and the requirement for real-time monitoring of the energy spectrum of the high-repetition-frequency pulse X-ray source cannot be met.

In 2018, k.t.behm et al utilized a scintillator array consisting of 33 × 47 CsI scintillators placed in lead panes, where the radiation was incident from the shorter side of the array, so that 47 scintillators in each row formed a filter stack spectrometer channel, and the optical signals of the scintillators were read out by a 1024 × 1024 array of Charge Coupled Devices (CCD), which enabled on-line measurement of the energy spectrum from a 0.1MeV to 30MeV pulsed X source. However, in the spectrometer design of Behm et al, only the lead and CsI with the same thickness are selected for the filter and the scintillator, and the efficiency of detecting high-flux X-rays with energy lower than 100keV is low. The CCD is used for measuring the scintillator optical signal, the spectrometer has low integration level and is difficult to be applied in a vacuum target chamber with limited space; the cost of using the CCD is high, the exposure and reading time of the CCD is long (in the order of milliseconds to ten milliseconds), and secondary noise cannot be distinguished; and CCD does not do optical coupling in the scintillator, the light collection efficiency uncertainty is big, it is difficult to accurate quantitative description incident X ray's intensity.

In summary, for a pulsed X-ray source energy spectrum measurement system, there is no good design scheme at present to ensure high detection efficiency and online real-time energy spectrum measurement capability in a wide energy range (10keV to 10 MeV).

Disclosure of Invention

Aiming at the technical problem, the invention provides an online filter stack spectrometer which can realize online real-time measurement of a wide energy band (10 keV-10 MeV) and a pulse type X-ray source energy spectrum based on the combination of a diamond detector and a scintillator detector.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an online filter stack spectrometer comprises

The radiation sensitive unit is sequentially formed by at least one diamond detector and a plurality of scintillator detectors in a stacking mode and is used for detecting wide-energy-band pulse X-rays, the diamond detector generates a current pulse signal, and the scintillator detectors generate a visible light signal;

the photoelectric conversion unit receives visible light signals generated by a scintillator detector in the ray sensitive unit through an optical fiber, converts the visible light signals into electric signals and then processes the electric signals by an electronic system;

the electronic system is used for receiving and processing a current pulse signal generated by a diamond detector in the ray sensitive unit and an electric signal output by the photoelectric conversion unit into a digital signal so as to solve the energy spectrum of the pulse type X ray in real time according to the signal intensity detected by the ray sensitive unit;

a deflection magnet for deflecting high-energy electrons emitted along with the X-rays; and

and the aiming camera is used for aiming the X-ray source so that X-rays can penetrate through the multi-layer ray sensitive units.

Specifically, the photoelectric conversion unit includes a photodiode or/and a photomultiplier tube.

When the photoelectric conversion unit adopts a photodiode and a photomultiplier, X-ray flux is higher for a plurality of layers of scintillator detectors close to an X-ray incidence end and mainly low-energy-band X-rays interacted with each other, and visible light flux generated by a scintillator in a single-shot pulse is higher, so that the photoelectric conversion of the unit adopts the photomultiplier-free photodiode, and the saturation of signals at a photoelectric conversion part is avoided; for the last several layers of scintillator detectors, the interaction of the X-ray detector is mainly X-ray in a high energy band, the X-ray flux is low, and the visible light flux generated by the scintillator in a single pulse is low, so the photoelectric conversion adopts a photomultiplier tube with multiplication function, specifically a silicon photomultiplier (SiPM), to improve the signal-to-noise ratio of the signal. The specific choice of photodiode or photomultiplier depends on the application. And the current signal of the photoelectric conversion unit is output by the SMA radio frequency signal interface.

Specifically, the electronic system comprises a front-end electronic system, a rear-end electronic system and a power supply system, wherein the front-end electronic system is used for converting current signals output by the diamond detector and the photoelectric conversion unit into voltage signals and processing the voltage signals and then outputting analog waveform signals, the rear-end electronic system adopts a digital acquisition card and is used for digitally sampling, caching and transmitting the analog waveform signals output by the front-end electronic system, and the power supply system is used for supplying power to the front-end electronic system, the rear-end electronic system, the photoelectric conversion unit and the diamond detector.

Specifically, the front-end electronics system comprises a transimpedance amplifier, a filter shaping circuit, a trigger circuit and a complex programmable logic device, wherein the transimpedance amplifier is used for converting current signals output by the diamond detector and the photoelectric conversion unit into voltage signals, the filter shaping circuit is used for carrying out amplitude phase adjustment and filtering on the voltage signals output by the transimpedance amplifier, the trigger circuit is used for generating single-channel trigger signals, the complex programmable logic device is used for judging trigger logic, and when multiple channels are triggered simultaneously, final trigger signals are output.

Specifically, the trigger circuit employs a hysteresis comparator.

Specifically, the front end electronics system and the back end electronics system are each configured as 16 channels.

Specifically, the radiation sensitive unit includes at least one diamond detector and a plurality of scintillator detectors arranged in sequence in a stacked manner from an X-ray incidence direction, and a filter interposed between adjacent detectors to attenuate X-rays, wherein a scintillator thickness of the scintillator detectors is gradually increased. Aiming at the condition that the flux of low-energy X rays in the pulse X-ray source is extremely high, a diamond detector with high radiation-resistant intensity is adopted at the front end of the ray sensitive unit to detect the low-energy X rays, and the X rays are directly converted into electric signals and then read out by an electronic system. The specific number of the diamond detectors and the scintillator detectors is determined according to the application scene requirements, and the filter disc is made of corresponding thickness and materials according to the application scene requirements.

Specifically, the diamond detector adopts a thin-sheet diamond detector, and the thickness of the thin-sheet diamond detector is 50-400 microns.

Specifically, the thickness of the scintillator in the scintillator detector is 5 mm-10 cm.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, a ray sensitive unit adopts a filter stack mode formed by combining a diamond detector and a scintillator detector, the diamond detector is used as an X-ray sensitive medium, can directly convert X-rays into electric signals and can bear extremely high radiation intensity, the effective measurement of the total flux of high-flux X-rays in a low-energy section is realized, the scintillator detector is used as an X-ray sensitive medium, and can convert X-rays into visible light and convert the visible light into the electric signals, the high-efficiency measurement of high-energy X-rays is realized, the detection efficiency in 100 keV-10 MeV is more than 10%, and the electric signals are processed and adopted at high speed by combining an electronic system, so that the online real-time measurement of energy spectrums of wide-energy sections (10 keV-10 MeV) and pulse X-ray sources is realized. The invention has the advantages of ingenious design, simple structure and convenient use, and is suitable for application in X-ray measurement.

(2) The invention uses the photodiode and the silicon photomultiplier as the photoelectric conversion unit, uses the light guide and the optical fiber as the coupling medium of the scintillator and the photoelectric conversion unit, and has low cost, high integration and good stability.

(3) The invention adopts a 16-channel electronic system for signal processing and digitization, and can effectively realize the functions of communication with a digital acquisition card, detector configuration, energy spectrum inverse solution and data visualization by matching with a back-end computer-end application program.

Drawings

Fig. 1 is a schematic overall structure diagram of an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a radiation-sensitive unit in an embodiment of the present invention.

In the drawings, the names of the parts corresponding to the reference numerals are as follows:

the method comprises the following steps of 1-aiming a camera, 2-deflection magnets, 3-ray sensitive units, 4-light guides or optical fibers, 5-photoelectric conversion units, 6-front-end electronics, 7-rear-end electronics, 8-power system, 9-computer-end application program, 10-diamond detector, 11-scintillator detector and 12-filter.

Detailed Description

The present invention is further illustrated by the following figures and examples, which include, but are not limited to, the following examples.

Examples

As shown in fig. 1 to 2, the online filter stack spectrometer mainly includes a collimating camera 1, a deflecting magnet 2, a radiation sensitive unit 3, a photoelectric conversion unit 5, and an electronic system, and a computer application program 9 may be configured at the back end of the online filter stack spectrometer.

The targeting camera 1 is used for aiming the X-ray source so that X-rays can penetrate through the multi-layer ray sensitive units.

The deflection magnet 2 is used for deflecting high-energy electrons emitted along with the X-ray and eliminating the influence of the electrons on the X-ray energy spectrum measurement.

Ray sensitive unit 3 adopts diamond detector and scintillator detector to make up into the filter stack for detect wide energy section pulsed X ray, diamond detector produces current pulse signal, the scintillator detector produces visible light signal. The radiation sensitive unit specifically includes at least one diamond detector 10 and a plurality of scintillator detectors 11 arranged in sequence in a stacked manner from the X-ray incidence direction, and a filter 12 interposed between the adjacent detectors to attenuate X-rays, wherein the scintillator thickness of the scintillator detectors is gradually increased. The ray sensitive units are numbered from left to right as C1, F1, C2, F2, S1, F3, S2, F4, S3, F5, S4, F6, S5, F7, S6, F8, S7, F9 and S8 in the ray sensitive units shown in FIGS. 1 and 2, wherein F1-F9 represent filters, C1 and C2 are sheet diamond detectors, and S1-S8 are scintillator detectors. Aiming at the condition that the flux of low-energy X rays in the pulse X-ray source is extremely high, a diamond detector with high radiation-resistant intensity is adopted at the front end of the ray sensitive unit to detect the low-energy X rays, and the X rays are directly converted into electric signals and then read out by an electronic system. The thickness of the diamond detector is 50-400 mu m. The diamond detector is used as an X-ray sensitive medium, can directly convert X-rays into electric signals, can resist extremely high radiation intensity, and can effectively measure the total flux of low-energy-band high-flux X-rays, thereby obtaining the energy spectrum of a ray source. Then, the detector is connected with an eight-channel scintillator detector, and the scintillator converts the X-rays into visible light which is processed by a subsequent photoelectric conversion unit. The thickness of the scintillator in the scintillator detector is 5 mm-10 cm. The scintillator is used as an X-ray sensitive medium, a photoelectric conversion unit is matched to carry out photoelectric conversion on signals output by the scintillator, an optical fiber, a light guide coupling scintillator and a photoelectric conversion device are used, high-efficiency measurement of a pulse X-ray line width energy section is achieved with low cost, high integration degree and high stability, and the detection efficiency of 100 keV-10 MeV is over 10%. The filter disc adopts corresponding thickness and material according to the application scene requirements.

The photoelectric conversion unit 5 receives visible light signals generated by a scintillator detector in the ray sensitive unit through a light guide or an optical fiber 4, converts the visible light signals into electric signals, and then processes the electric signals by an electronic system. The photoelectric conversion unit may specifically employ a photodiode and a photomultiplier tube. For X-rays which are mainly in a low-energy section and interact with a plurality of layers of scintillator detectors close to an X-ray incidence end, the X-ray flux is higher, and the visible light flux generated by the scintillators in a single-shot pulse is higher, so that a photomultiplier-free photodiode is adopted for photoelectric conversion, and signals are prevented from being saturated in a photoelectric conversion part; for the last several layers of scintillator detectors, the interaction of the X-ray detector is mainly X-ray in a high energy band, the X-ray flux is low, and the visible light flux generated by the scintillator in a single pulse is low, so the photoelectric conversion adopts a photomultiplier tube with multiplication function, specifically a silicon photomultiplier (SiPM), to improve the signal-to-noise ratio of the signal. The specific choice of photodiode or photomultiplier depends on the application. And the current signal of the photoelectric conversion unit is output by the SMA radio frequency signal interface.

And the electronic system is used for receiving and processing the current pulse signals generated by the diamond detector in the ray sensitive unit and the electric signals output by the photoelectric conversion unit into digital signals so as to solve the energy spectrum of the pulse type X rays in real time according to the signal intensity detected by the ray sensitive unit.

In particular, the electronics system includes a front-end electronics system 6, a back-end electronics system 7 and a power supply system 8. The front-end electronic system comprises a trans-impedance amplifier, a filter forming circuit, a trigger circuit and a complex programmable logic device which are all configured to be 16 channels. The SMA radio frequency signal interface receives the current signal output by the photoelectric conversion unit, and the signal is transmitted to the 16-channel trans-impedance amplifier and is used for converting the current signal output by the diamond detector and the photoelectric conversion unit into a voltage signal; the 16-channel filtering and forming circuit is used for carrying out amplitude phase adjustment and filtering on the voltage signal output by the trans-impedance amplifier, so that subsequent analog-digital conversion is facilitated; the trigger circuit adopts a 16-channel hysteresis comparator for generating a single-channel trigger signal, the complex programmable logic device is used for judging the 16-channel trigger logic, and when multiple channels are triggered simultaneously, the final trigger signal is output. The back-end electronic system adopts a 16-channel high-speed waveform sampling digital acquisition card, has the functions of a high-speed analog-digital converter (ADC), data caching, data transmission and the like, and is used for digitally sampling, caching and transmitting analog waveform signals output by the front-end electronic system. The power supply system is used for supplying power to the front-end electronic system, the rear-end electronic system, the photoelectric conversion unit and the diamond detector, and can be specifically configured as a power supply module of a 220V alternating current to 12V direct current electronic system and a power supply module of a 16-channel diamond detector, a photodiode and a photomultiplier, wherein the power supply module can output 0-80V power.

In addition, the spectrometer is also provided with a computer end application program 9 which comprises functions of communication with a digital acquisition card, detector configuration, energy spectrum inverse solution and data visualization.

The working principle of the invention is as follows: the X-ray reacts with the diamond detector to ionize electron-hole pairs in the diamond detector, and bias voltage is applied to two ends of the diamond detector to enable the electron-hole pairs to drift to form current pulse signals. The X-ray reacts with the scintillator detector to excite the scintillator to generate visible light signals, and the visible light signals irradiate the biased silicon photomultiplier or the photodiode to form current pulse signals. The current pulse signal generated by the detector is amplified and shaped through a transimpedance amplifier and a filter forming circuit, then real-time analog-digital conversion is carried out through a digital acquisition card, the signal generated by the detector is converted into a digital signal, and the digital signal is transmitted to a computer end application program for processing. The signal intensity of the diamond detectors or the scintillator detectors of different layers can be used for reversely solving the energy spectrum of the incident pulse X-ray in real time, so that the online energy spectrum measurement of the X-ray pulse radiation field is realized.

The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, but all changes that can be made by applying the principles of the present invention and performing non-inventive work on the basis of the principles shall fall within the scope of the present invention.