CN101013095A - Positron annihilation lifetime spectrometer - Google Patents
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Abstract
一种正电子湮没寿命谱测量的谱仪，其特点在于该正电子湮没寿命谱仪采用以氯化镧晶体为闪烁体的探测器。氯化镧晶体不仅有快速的时间响应，而且具有比BaF2晶体优越很多的能量分辨率。因此，可以利用能量窗选择电路，将起始道探测器和停止道探测器所接受的信号限制在一个很窄的能量范围内，可以有效地排除其它来源(样品材料，环境等)的γ辐射对测量过程的影响，大大降低寿命谱的本底，使该谱仪的探测器在保持快时间响应的同时还具备更好的能量分辨率，从而可在强γ射线干扰下进行正电子湮没寿命谱测量，达到提取正电子湮没寿命谱有效信息的目的。
A spectrometer for positron annihilation lifetime spectrum measurement is characterized in that the positron annihilation lifetime spectrometer adopts a detector using lanthanum chloride crystal as a scintillator. Lanthanum chloride crystal not only has fast time response, but also has much superior energy resolution than BaF 2 crystal. Therefore, the energy window selection circuit can be used to limit the signals received by the start track detector and stop track detector to a very narrow energy range, which can effectively exclude gamma radiation from other sources (sample material, environment, etc.) The impact on the measurement process greatly reduces the background of the lifetime spectrum, so that the detector of the spectrometer has better energy resolution while maintaining a fast time response, so that the positron annihilation lifetime can be performed under strong γ-ray interference Spectrum measurement, to achieve the purpose of extracting effective information of positron annihilation lifetime spectrum.
Description
Technical field
The present invention relates to a kind of positron annihilation life spectrometer (Positron Annihilation LifetimeSpectrometer), particularly a kind of adopt novel lanthanum chloride crystal be scintillator detector, can be anti-the positron annihilation life spectrometer that disturbs of intense gamma radiation.
Background technology
Positron annihilation technique has become the mature technology of being used widely at present through developing rapidly for many years in fields such as solid state physics, metal physics and material science.Positron annihilation technique has many advantages, and itself is a kind of nondestructive research method, does not need the sample of special preparation.And since experiment gained information be by penetrative quality very strong annihilation gammas carry, thereby very easy as on-the-spot and original position research.
Inject material from positron and be commonly referred to as positron life to take place falling into oblivion the time of being experienced.Defectives such as dislocation that solid defects such as deformation, irradiation damage etc. produced and room and cavity all can cause the variation of local electronic density, thereby positron annihilation life τ is also changed.So, can study the variation of substance characteristics by the variation of τ, this is one of main application facet of present positron annihilation technique.The core of positron annihilation lifetime measurement device is one and meets time measurement system soon that it mainly is divided into three parts: the scintillator photomultiplier tube detectors, in order to survey the γ photon; Meet the time spectrometer soon, be used to measure the mistiming of twice incident; The microcomputer multichannel pulse scope-analyzer be used for showing and writing time spectrum (list of references: He Yuanjin, Ma Xingkun edits " Experiments of Modern Physics " (publishing house of Tsing-Hua University, 2003), tests 13 positron annihilation lifetime measurements, pp171-184).
In traditional positron annihilation life spectrometer, the start channel of Measuring Time signal and stop way detector generally are made up of fast scintillator and fast response photomultiplier coupling.This fast scintillator is generally plastic scintillant or BaF
2(barium fluoride) crystal.Accept the initial sum stop signal of an annihilation events respectively in order to limit start channel detector and stop way detector, generally need to adopt coincidence circuit that the amplitude (being the energy of γ radioactive ray) of signal is selected.For employing
22Na is as the instrument of positron source, and start channel signal energy scope should be the center with 1.28MeV, and stop way signal energy scope should be the center with 0.511MeV.Select suitable energy window can reduce the chance that scattering and radioactivity background cause and meet, make measured positron annihilation lifetime spectrum more can reflect the physical state of sample truly.
In other words, in positron annihilation life spectrometer, we not only require detector to provide time signal, also require it to provide energy signal.Although the given energy signal resolution of fast scintillator is not high, can satisfy the above-mentioned requirement that signal energy is selected in the ordinary course of things.
But when the measured sample of positron life spectrometer itself had gamma activity, situation was just different fully.If the radioactivity of sample itself is quite strong, and its energy and 0.511MeV or 1.28MeV quite near the time, traditional BaF
2Crystal counter just can't be distinguished the gamma activity of sample itself and the gamma activity of positron source, causes high background, can make the positron annihilation lifetime spectrum distortion when serious, makes the instrument cisco unity malfunction.
In addition, when having stronger background γ radiation around the working environment of positron annihilation life spectrometer, when for example carrying out the irradiation effect in site measurement of certain sample, similar above-mentioned situation also may appear.
Above the question resolves itself into a bit promptly requires to have a kind of spectrometer that can carry out positron annihilation lifetime measurement under strong gamma-rays disturbs.Its main points are that the detector of this spectrometer is keeping also should possessing better energy resolution in fast time response.
With detector BaF the most frequently used in the present positron annihilation life spectrometer
2Scintillator detector is an example, BaF
2Detector is to the gamma-ray energy resolution about 14% of 0.511MeV, that is about 72keV, if radioactive sample itself contains the gamma ray projector of energy between 475KeV～547KeV, then this signal can seriously be sneaked into the signal stop way, causes the life spectrometer cisco unity malfunction.
Summary of the invention
At the deficiencies in the prior art and defective, the object of the present invention is to provide a kind of positron annihilation life spectrometer, make the detector of this spectrometer keep also possessing better energy resolution in fast time response, can under strong gamma-rays disturbs, carry out positron annihilation lifetime measurement.
Technical scheme of the present invention is as follows:
A kind of positron annihilation life spectrometer, comprise two detectors of start channel and stop way, meet time spectrometer and microcomputer multichannel pulse scope-analyzer soon, each detector is coupled to form by scintillator and photomultiplier, described meet soon the time spectrometer contain fast coincidence circuit, be provided with the start channel energy window the constant proportion timing discrminator, be provided with the stop way energy window the constant proportion timing discrminator and the time width of cloth converter, it is characterized in that: described scintillator adopts the lanthanum chloride scintillator.
Technical characterictic of the present invention also is: described start channel energy window is the energy window of energy range at 1.2MeV-1.30MeV; The stop way energy window is the energy window of energy range at 0.49MeV-0.53MeV.
The present invention compared with prior art has the following advantages and the high-lighting effect.Employing is the positron annihilation life spectrometer of the detector of scintillator with the lanthanum chloride crystal, and not only arranged time response fast, and has the BaF of ratio
2The superior a lot of energy resolution of crystal.Therefore, can utilize energy window to select circuit, the signal limitations that start channel detector and stop way detector are accepted is in a very narrow energy range, can get rid of other source (specimen material effectively, environment etc.) γ radiation is to the influence of measuring process, reduce the background of life spectrum greatly, make the detector of this spectrometer keep also possessing better energy resolution in fast time response, thereby can under strong gamma-rays disturbs, carry out positron annihilation lifetime measurement, reach the purpose of extracting the positron annihilation lifetime spectrum effective information.
Description of drawings
Fig. 1 is the one-piece construction synoptic diagram of positron annihilation life spectrometer provided by the invention.
Fig. 2 is for being the structural representation of the detector of scintillator with the lanthanum chloride crystal.
Fig. 3 is start channel power spectrum full figure and sets the later energy spectrogram of energy window.
Fig. 4 is the power spectrum full figure of stop way and sets the later energy spectrogram of energy window.Wherein, curve A is the power spectrum full figure, and curve B is for setting the later energy spectrogram of energy window.
Embodiment
Fig. 1 is the one-piece construction synoptic diagram of positron annihilation life spectrometer provided by the invention.This spectrometer comprises start channel and two detectors of stop way, meets time spectrometer and microcomputer multichannel pulse scope-analyzer soon, and each detector is coupled to form by lanthanum chloride scintillator 1 and photomultiplier 2, and high-voltage power supply is supplied with the required high pressure of photomultiplier work.Described meet soon the time spectrometer contain fast coincidence circuit, be provided with the start channel energy window the constant proportion timing discrminator, be provided with the stop way energy window the constant proportion timing discrminator and the time width of cloth converter.Lanthanum chloride crystal is a kind of novel scintillation crystal of finding before and after 2000 in the world, it not only has very fast time response, and have can energy resolution, by international report, Φ 25 * 25mm lanthanum chloride crystal is 4.2% (list of references: Marcin Balcerzyk to the gamma-ray energy resolution of 662keV, Marek Moszyn ' ski, Maciej KapustaComparison of LaCl
3: Ce and NaI (Tl) scintillators in g-ray spectrometry NuclearInstruments and Methods in Physics Research A 537 (2005) 50-56).Therefore this crystal can be used for making up the above-mentioned positron annihilation life spectrometer that can work fully under intense gamma radiation is disturbed.The theory diagram of this positron annihilation life spectrometer such as Fig. 1.The detector that has wherein adopted the coupling of two lanthanum chloride crystals and fast response photomultiplier to constitute.This is the major different of this spectrometer and traditional positron annihilation life spectrometer; In addition, also having than big difference aspect the selection of energy window with traditional life spectrometer, this spectrometer can set very narrowly by window.The start channel energy window is set at 1.2MeV-1.30MeV; The stop way energy window is set at 0.49MeV-0.53MeV, and the system that guaranteed well resists strong γ background radiation effects of jamming to the gamma-ray examination of energy except that 1.28MeV and 0.511MeV thereby reached.
When positron annihilation life spectrometer is in the lifetime measurement mode of operation, start channel detector photomultiplier anode signal process is provided with the constant proportion timing discrminator of energy window and delays time width of cloth converter when sending into as start signal later on, and stop way detector photomultiplier anode signal process is provided with the constant proportion timing discrminator of energy window and the width of cloth converter when sending into as stop signal later on of delaying time, the time width of cloth converter pulse signal that converted to certain amplitude the mistiming between start signal and the stop signal send the microcomputer multichannel analyzer to via the signal Port Multiplier and carry out the amplitude analysis, the gained time spectrum is positron annihilation lifetime spectrum.When positron annihilation life spectrometer is in energy window adjustment mode of operation, after amplifying through amplifier, photomultiplier dynode signal sends the input end of microcomputer multichannel analyzer to via the signal Port Multiplier, the energy signal of start channel constant proportion timing discrminator and the output of stop way constant proportion timing discrminator is then sent microcomputer multichannel analyzer gate terminals to as gate-control signal, and multichannel analyzer just can show the adjustable power spectrum of energy window like this.
Fig. 2 wherein scribbles the optical coupled silicone grease for being the structural representation of the detector of scintillator with the lanthanum chloride crystal between lanthanum chloride scintillator 1 and the photomultiplier 2, the magnetic shielding 3 of permalloy material is used to shield the interference of stray EM field to photomultiplier.Shell body 4 usefulness steel plates are made, and it fixedly becomes detector integral body with lanthanum chloride scintillator and photomultiplier, and high-voltage bleeder circuit 5 provides photomultiplier work required each electrode voltage.
The energy spectrogram that the power spectrum full figure of Fig. 3 and Fig. 4 difference start channel and stop way and setting energy window are later, wherein, curve A is the power spectrum full figure, curve B is to set the later energy spectrogram of energy window.0.511MeV among the figure and 1.28MeV photoelectricity Butt curve are carried out the energy resolution that match can get the lanthanum chloride scintillator detector, detector is about 6% to the gamma-ray energy resolution of 0.511MeV in the present embodiment, and the initial gamma energy of 1.28MeV is distinguished as 4%.The energy range of start channel energy window is 1.2MeV-1.30MeV; The energy range of stop way energy window is 0.49MeV-0.53MeV;
By the selection of narrow energy window, can get rid of the gamma-emitting interference of other background effectively, guarantee the normal measurement of positron annihilation lifetime spectrum.
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| CN101923062A (en) * | 2010-09-02 | 2010-12-22 | 武汉大学 | A mobile digital positron lifetime spectrometer |
| CN102495422A (en) * | 2011-12-05 | 2012-06-13 | 北京大学 | Connection and protection device for photo-multiplier tube detector |
| CN103336020A (en) * | 2013-07-17 | 2013-10-02 | 苏州热工研究院有限公司 | Positron lifetime spectrum measurement system and adopted measurement method thereof |
| CN106371132A (en) * | 2016-09-23 | 2017-02-01 | 中国科学院高能物理研究所 | Method for positron annihilation lifetime spectrum measurement, system and scintillation detector |
| CN106443758A (en) * | 2016-09-07 | 2017-02-22 | 中国科学院高能物理研究所 | Anticoincidence based positron annihilation detecting method and system |
| CN106547017A (en) * | 2016-11-22 | 2017-03-29 | 清华大学 | A kind of compound scintillator gamma ray spectrometer |
| CN106680300A (en) * | 2017-01-17 | 2017-05-17 | 武汉大学 | Multidimensional positron annihilation lifetime spectrum and doppler broadening spectrum measurement systems |
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| CN107272047A (en) * | 2017-06-14 | 2017-10-20 | 中国科学院高能物理研究所 | Positron annihilation lifetime measurement method and system |
| CN110585607A (en) * | 2011-03-31 | 2019-12-20 | 反射医疗公司 | System and method for use in emission guided radiation therapy |
| CN112033981A (en) * | 2020-09-09 | 2020-12-04 | 华中科技大学无锡研究院 | A kind of lithium ion battery lithium evolution detection method |
| CN113640852A (en) * | 2021-09-18 | 2021-11-12 | 中国科学技术大学 | A Positron Annihilation Lifetime Spectrometer for Measuring Thin Film Samples |
| CN113655513A (en) * | 2021-08-16 | 2021-11-16 | 中国科学技术大学 | Digitized anti-coincidence multi-path interaction-starting positron annihilation life spectrometer |
| CN113721286A (en) * | 2021-08-16 | 2021-11-30 | 中国科学技术大学 | Positron annihilation life spectrometer for pulse discrimination by using support vector machine |
| CN114137598A (en) * | 2021-11-05 | 2022-03-04 | 北京大学 | A positive and negative electron magnetic spectrometer |
| CN115032679A (en) * | 2022-05-10 | 2022-09-09 | 中国科学院高能物理研究所 | Two-dimensional positron annihilation lifetime spectrum measuring method and system |
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| US11627920B2 (en) | 2008-03-14 | 2023-04-18 | Reflexion Medical, Inc. | Method and apparatus for emission guided radiation therapy |
| CN101923062A (en) * | 2010-09-02 | 2010-12-22 | 武汉大学 | A mobile digital positron lifetime spectrometer |
| CN110585607A (en) * | 2011-03-31 | 2019-12-20 | 反射医疗公司 | System and method for use in emission guided radiation therapy |
| CN102495422A (en) * | 2011-12-05 | 2012-06-13 | 北京大学 | Connection and protection device for photo-multiplier tube detector |
| CN102495422B (en) * | 2011-12-05 | 2013-12-25 | 北京大学 | Connection and protection device for photo-multiplier tube detector |
| CN103336020A (en) * | 2013-07-17 | 2013-10-02 | 苏州热工研究院有限公司 | Positron lifetime spectrum measurement system and adopted measurement method thereof |
| CN103336020B (en) * | 2013-07-17 | 2015-07-15 | 苏州热工研究院有限公司 | Positron lifetime spectrum measurement system and adopted measurement method thereof |
| CN106443758A (en) * | 2016-09-07 | 2017-02-22 | 中国科学院高能物理研究所 | Anticoincidence based positron annihilation detecting method and system |
| CN106371132A (en) * | 2016-09-23 | 2017-02-01 | 中国科学院高能物理研究所 | Method for positron annihilation lifetime spectrum measurement, system and scintillation detector |
| CN106371132B (en) * | 2016-09-23 | 2019-03-15 | 中国科学院高能物理研究所 | Method, system and scintillation detector for positron annihilation lifetime spectroscopy |
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| CN106814094B (en) * | 2017-01-13 | 2019-09-10 | 武汉大学 | A kind of Low background dopplerbroadening depth distribution measuring system and measurement method |
| CN106814094A (en) * | 2017-01-13 | 2017-06-09 | 武汉大学 | A kind of Low background dopplerbroadening depth profile measuring system and measuring method |
| CN106680300B (en) * | 2017-01-17 | 2019-04-09 | 武汉大学 | Multidimensional Positron Annihilation Lifetime Spectroscopy and Doppler Broadening Spectrum Measurement System |
| CN106680300A (en) * | 2017-01-17 | 2017-05-17 | 武汉大学 | Multidimensional positron annihilation lifetime spectrum and doppler broadening spectrum measurement systems |
| CN107272047A (en) * | 2017-06-14 | 2017-10-20 | 中国科学院高能物理研究所 | Positron annihilation lifetime measurement method and system |
| CN107272047B (en) * | 2017-06-14 | 2019-06-28 | 中国科学院高能物理研究所 | Positron annihilation lifetime measurement method and system |
| US12251579B2 (en) | 2020-08-07 | 2025-03-18 | Reflexion Medical, Inc. | Multi-sensor guided radiation therapy |
| CN112033981A (en) * | 2020-09-09 | 2020-12-04 | 华中科技大学无锡研究院 | A kind of lithium ion battery lithium evolution detection method |
| CN113721286A (en) * | 2021-08-16 | 2021-11-30 | 中国科学技术大学 | Positron annihilation life spectrometer for pulse discrimination by using support vector machine |
| CN113721286B (en) * | 2021-08-16 | 2023-07-14 | 中国科学技术大学 | A Positron Annihilation Lifetime Spectrometer Using Support Vector Machines for Pulse Discrimination |
| CN113655513A (en) * | 2021-08-16 | 2021-11-16 | 中国科学技术大学 | Digitized anti-coincidence multi-path interaction-starting positron annihilation life spectrometer |
| CN113640852B (en) * | 2021-09-18 | 2024-08-09 | 中国科学技术大学 | A positron annihilation lifetime spectrometer for measuring thin film samples |
| CN113640852A (en) * | 2021-09-18 | 2021-11-12 | 中国科学技术大学 | A Positron Annihilation Lifetime Spectrometer for Measuring Thin Film Samples |
| CN114137598B (en) * | 2021-11-05 | 2022-06-07 | 北京大学 | Positive and negative electron magnetic spectrometer |
| CN114137598A (en) * | 2021-11-05 | 2022-03-04 | 北京大学 | A positive and negative electron magnetic spectrometer |
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