WO2021060930A1 - Scintillateur pour la mesure de rayons gamma/neutrons, procédé de fabrication de scintillateur et procédé de séparation et de mesure faisant appel au scintillateur - Google Patents

Scintillateur pour la mesure de rayons gamma/neutrons, procédé de fabrication de scintillateur et procédé de séparation et de mesure faisant appel au scintillateur Download PDF

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Publication number
WO2021060930A1
WO2021060930A1 PCT/KR2020/013123 KR2020013123W WO2021060930A1 WO 2021060930 A1 WO2021060930 A1 WO 2021060930A1 KR 2020013123 W KR2020013123 W KR 2020013123W WO 2021060930 A1 WO2021060930 A1 WO 2021060930A1
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scintillator
neutrons
gamma rays
manufacturing
gamma
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PCT/KR2020/013123
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English (en)
Korean (ko)
Inventor
김홍주
부옹 판콕
김성환
칸아사드
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경북대학교 산학협력단
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Publication of WO2021060930A1 publication Critical patent/WO2021060930A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/62—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing gallium, indium or thallium

Definitions

  • the present invention relates to a scintillator for measuring gamma rays/neutrons, a method for manufacturing a scintillator, and a separation measurement method using the scintillator.
  • LiI:Eu scintillator is a representative neutron detector using the characteristic that Li ions react with neutrons, and although commercially available, gamma rays are also measured, so there is a problem that two radiations cannot be distinguished in a radiation field where gamma rays and neutrons are mixed.
  • FIG. 1 is a view showing the results of simultaneously measuring 1461 keV of potassium-40 and 2615 keV of thorium-based gamma rays and thermal neutrons with a LiI:Eu scintillator. Referring to FIG. 1, it is shown that measurement signals of two radiations are mixed, and gamma rays and neutrons are not separated on the spectrum.
  • the present invention is intended to provide a scintillator for efficiently separating gamma rays/neutrons in a gamma ray/neutron mixture field.
  • the present invention also proposes a separation measurement method using a scintillator to efficiently separate gamma rays/neutrons in a gamma ray/neutron mixed field.
  • a LiI:X scintillator for measuring gamma-ray/neutron separation in a gamma-ray/neutron mixed field is disclosed.
  • the concentration of the active agent X may be 0 ⁇ X ⁇ 20 mol%.
  • a method for manufacturing a scintillator is disclosed.
  • moisture may be removed by heat treatment to grow the scintillator into a single crystal of good quality.
  • the manufacturing method may remove moisture by heat treatment at 150 ⁇ 20° C. for 20 hours or more.
  • the manufacturing method may perform moisture removal in a high vacuum of 10 -6 torr or more.
  • a method of separating and measuring gamma rays and neutrons using a scintillator using a maximum likelihood method is disclosed.
  • gamma rays and neutrons may be separated and measured.
  • the pulse shape index (SI) may be set to a range of -0.1 ⁇ SI ⁇ 0.1, gamma rays and neutrons may be measured separately.
  • the scintillator according to the present invention has an effect that separation of gamma rays and neutrons is easier than that of the conventional scintillator.
  • 1 is a view showing a wave height spectrum for gamma rays and neutrons using a LiI:Eu scintillator.
  • FIG. 2 is a diagram showing a scintillation time characteristic spectrum for gamma rays/neutrons of a cerium doped click (Cs 2 LiYCl 6 :Ce 3+; CLYC) scintillator.
  • FIG. 3 is a diagram showing a peak waveform spectrum measured by the maximum likelihood method using the scintillator according to the present invention.
  • FIG. 4 is a diagram showing a scintillation attenuation spectrum of gamma rays and neutrons measured using a scintillator according to the present invention.
  • FIG. 5 is a diagram showing a wave height spectrum in which gamma rays and neutrons are measured at the same time.
  • FIG. 6 is a diagram showing a wave height spectrum obtained by measuring only neutrons after separating gamma rays and neutrons by the maximum likelihood method.
  • FIG. 7(a) is a diagram showing a spectrum using a LiI:Ag scintillator omitting drying and purification processes.
  • 7(b) is a diagram showing a two-dimensional spectrum of gamma rays and neutrons separated and measured by a pulse shape classification method of a LiI:Ag scintillator grown after removing moisture through a drying and refining process according to the present invention.
  • the main content of the present invention relates to a LiI:X scintillator detector capable of separately measuring two radiations in a radiation field in which gamma rays and neutrons are mixed, a gamma ray/neutron separation measurement method using the same, and a method of manufacturing a LiI:X scintillator.
  • the LiI scintillator is very susceptible to moisture, and when it is exposed to moisture, it is impossible to grow a single crystal of the scintillator, so the drying process in the reagent was confirmed.
  • the present invention discloses a method of manufacturing a scintillator having an optimum separation effect by limiting the temperature and time of the drying process.
  • the parent LiI reacts with neutrons or gamma rays to absorb energy into the scintillator.
  • Sn, Ag, Tl, In doped with the activator in the LiI:X scintillator receives energy absorbed from the parent and the excited electrons recombine at the luminescent center of the activator, causing a scintillation phenomenon.
  • energy conversion efficiency may vary depending on the type and combination of the activator, and the luminous wavelength or flash attenuation time characteristics may change.
  • Gamma rays and neutrons cause ionization in the scintillator.
  • the difference in charge density of the electrons generated by the physical properties of the two radiations occurs, and the difference in the flash time characteristics occurs due to the difference in energy conversion efficiency between the parent and the active agent, and this can be evaluated and measured separately.
  • the element X which is an activator, may be transformed into a trivalent rare earth or a transition metal to be applied.
  • trivalent rare earth or transition metal when trivalent rare earth or transition metal is used as an activator, the measurement effect of separating gamma rays and neutrons may be partially insufficient compared to the case of applying Sn, Ag, Tl, and In as activators.
  • the concentration of the active agent X in the LiI:X scintillator may satisfy 0 ⁇ X ⁇ 20 mol%.
  • the activator X may serve to increase the luminous efficiency of the scintillator.
  • the concentration of the activator is excessively increased, there is a problem in that the light output is rather reduced due to quenching by the activator.
  • the concentration of the activator (X) exceeds 20 mol%, the light output rapidly decreases, and the concentration of the activator X in the LiI:X scintillator may satisfy 0 ⁇ X ⁇ 20 mol%.
  • FIG. 3 is a diagram showing a peak waveform spectrum measured by the maximum likelihood method using the scintillator according to the present invention.
  • FIG. 3 is a peak waveform spectrum obtained by measuring gamma rays and neutrons by the maximum likelihood method according to the present invention.
  • Two types of radiation can be clearly distinguished and measured in a radiation field in which gamma rays and neutrons are mixed using the scintillator according to the present invention.
  • (1) represents a separated neutron measurement spectrum
  • (2) is a gamma ray measurement spectrum. That is, referring to FIG. 3, it can be seen that (1) and (2) are clearly separated and separated.
  • FIG. 4 is a diagram showing a scintillation attenuation spectrum of gamma rays and neutrons measured using a scintillator according to the present invention.
  • a signal of a neutron exhibits a much faster characteristic than that of a gamma ray according to a difference in the transition efficiency of the energy band due to the added activator. Using these features, gamma rays and neutrons can be measured separately.
  • a shape indicator (SI) for distinguishing the peaks of gamma rays and neutrons is defined by the following equation.
  • a i is the magnitude of the FADC output
  • W(t i ) is the load factor for the i-th time interval.
  • the load factor is Given by, where And Denotes the average value of each neutron and gamma ray measurement signal in the set time window area.
  • the shape index is Gamma rays and neutrons can be measured separately in the range of.
  • the shape index is determined from the difference in temporal characteristics of the gamma ray and neutron scintillation measurement signal.
  • a large SI index means that the difference in time characteristics between the two signals is large. In other words, this means that one measurement signal is very fast and the other measurement signal is very slow.
  • the maximum likelihood method is applicable to all scintillators with a difference in the decay time characteristics of the measurement signal of gamma rays and neutrons.
  • 5 is a diagram showing a wave height spectrum in which gamma rays and neutrons are measured at the same time.
  • 6 is a diagram showing a wave height spectrum obtained by measuring only neutrons after separating gamma rays and neutrons by the maximum likelihood method. 5 to 6, there is an effect of confirming that gamma rays and neutrons are measured separately.
  • 7(a) is a diagram showing a spectrum using a LiI:Ag scintillator omitting drying and purification processes.
  • 7(b) is a diagram showing a two-dimensional spectrum of gamma rays and neutrons separated and measured by a pulse shape classification method of a LiI:Ag scintillator grown after removing moisture through a drying and refining process according to the present invention.
  • the scintillator according to the present invention may remove moisture by heat treatment at 150 ⁇ 20° C. for 20 hours or more, and this moisture removal process may be processed in a high vacuum of 10 -6 torr.
  • the scintillator of LiI:Ag single crystal that has undergone an appropriate drying and purification process shows superior results in the separation measurement of gamma rays and neutrons than in the case of LiI:Ag omitting the drying and purification process.
  • a method of doping at least one of Sn, Ag, Tl, and In with an active agent is provided.
  • the conversion efficiency between energy bands is determined by doping one or more activators into the matrix. It also provides a method of removing free water and bound water of a scintillation material for single crystal growth of a scintillator.
  • LiI has a relatively low melting point of 469 degrees and has a cubic structure, so it is easy to grow a single crystal and has an economic advantage as a radiation detector because the unit cost of a main component and a doping element is very inexpensive.
  • the LiI:X scintillation detector has a figure of merit (FOM) for thermal neutrons of 2.2, which is effective in separating gamma rays/neutrons.
  • the LiI:X scintillator has a high reaction rate of Li with respect to neutrons, so that neutron detection efficiency is excellent.
  • the result of the present invention can be applied to a technique for separating two radiations in a region where gamma rays and neutrons are mixed, such as a nuclear power plant, a high energy accelerator laboratory, and a radioisotope production facility. Since neutrons have a greater biological effect than gamma rays, it is very important to separate and measure the dose evaluation of two radiations for radiation protection of radiation workers, and this can be measured using the scintillator of the present invention. In addition, neutrons and gamma rays generated by cosmic radiation are mixed at high altitudes, unlike ground where gamma rays are mainly present.
  • the present invention can be applied to radiation protection of high-altitude flight attendants according to the Living Environment Radiation Protection Act.
  • neutron dose evaluation in space development is a prerequisite for the safe operation of spacecraft and satellites, as well as spacecraft crew members, and is a major technology for detecting the presence of water, which is the most important for space development.
  • the scintillator of the present invention can be used for this.
  • since neutrons and gamma rays can be measured simultaneously, nuclear physics, high energy physics, industrial radiation measuring devices, and the like can also be used.

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  • Chemical & Material Sciences (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Organic Chemistry (AREA)
  • Measurement Of Radiation (AREA)

Abstract

L'invention concerne un scintillateur LiI:X pour la séparation et la mesure de rayons gamma/neutrons dans un champ mixte de rayons gamma/neutrons. Dans un procédé de fabrication du scintillateur, l'humidité peut être éliminée par traitement thermique afin de faire croître le scintillateur en un monocristal de bonne qualité. En faisant appel au scintillateur, les rayons gamma et les neutrons peuvent être séparés et mesurés à l'aide d'un procédé à maximum de vraisemblance.
PCT/KR2020/013123 2019-09-26 2020-09-25 Scintillateur pour la mesure de rayons gamma/neutrons, procédé de fabrication de scintillateur et procédé de séparation et de mesure faisant appel au scintillateur WO2021060930A1 (fr)

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KR20190119117 2019-09-26
KR10-2019-0119117 2019-09-26

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WO2021060930A1 true WO2021060930A1 (fr) 2021-04-01

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060043304A1 (en) * 2004-08-31 2006-03-02 Battelle Memorial Institute Apparatus and method for osl-based, remote radiation monitoring and spectrometry
US20070029493A1 (en) * 2005-06-27 2007-02-08 General Electric Company Gamma and neutron radiation detector
KR20150145742A (ko) * 2014-05-12 2015-12-31 경북대학교 산학협력단 섬광체, 이의 제조 방법 및 응용
US20160102247A1 (en) * 2014-10-10 2016-04-14 Lawrence Livermore National Security, Llc Plastic scintillators with high loading of one or more metal carboxylates
US20170355905A1 (en) * 2014-11-19 2017-12-14 The Regents Of The University Of California Novel thallium doped sodium, cesium or lithium iodide scintillators

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10261214B2 (en) * 2016-05-02 2019-04-16 Schlumberger Technology Corporation Method and apparatus for separating gamma and neutron signals from a radiation detector and for gain-stabilizing the detector

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060043304A1 (en) * 2004-08-31 2006-03-02 Battelle Memorial Institute Apparatus and method for osl-based, remote radiation monitoring and spectrometry
US20070029493A1 (en) * 2005-06-27 2007-02-08 General Electric Company Gamma and neutron radiation detector
KR20150145742A (ko) * 2014-05-12 2015-12-31 경북대학교 산학협력단 섬광체, 이의 제조 방법 및 응용
US20160102247A1 (en) * 2014-10-10 2016-04-14 Lawrence Livermore National Security, Llc Plastic scintillators with high loading of one or more metal carboxylates
US20170355905A1 (en) * 2014-11-19 2017-12-14 The Regents Of The University Of California Novel thallium doped sodium, cesium or lithium iodide scintillators

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KR20210037586A (ko) 2021-04-06

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