JP6343773B2 - Method for producing translucent ZnS / 10B converter neutron scintillator - Google Patents

Description

The present invention relates to a translucent neutron scintillator that combines a zinc sulfide (ZnS) phosphor and ¹⁰ B, which is a neutron converter. More specifically, a ¹⁰ B-containing adhesive substance based on ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ) and a modified alicyclic polyamine, modified aliphatic polyamine or aliphatic diamine is used as a neutron converter and adhesive. In addition, the present invention relates to a translucent ZnS / ¹⁰ B converter neutron scintillator produced by mixing with zinc sulfide (ZnS) phosphor and a method for manufacturing the same.

Conventionally, a neutron detector in which a neutron scintillator containing ⁶ Li or ¹⁰ B, which is a neutron converter, and a photodetection element such as a photomultiplier tube have been used for neutron detection.

In the neutron scintillator, the nuclear reaction between ⁶ Li, which is a neutron converter, and neutrons:
n + ⁶ Li-> ³ H + α
Detecting triton ( ³ H) and alpha rays emitted by neutrons, or nuclear reaction between neutron converter ¹⁰ B and neutrons:
n + ¹⁰ B-> ⁷ Li + α
Neutron detection is performed by detecting ⁷ Li and alpha rays emitted by the neutron.

As a translucent neutron scintillator, after mixing silver activated zinc sulfide (ZnS: Ag) phosphor or copper activated zinc sulfide (ZnS: Cu) phosphor and ⁶ LiF which is a neutron converter, it is mixed with an adhesive, A ZnS / ⁶ LiF translucent neutron scintillator produced by applying to a substrate has been commercially available and has been widely used for many years (Non-Patent Document 1). In the case of a silver activated zinc sulfide (ZnS: Ag) phosphor, it is used for a neutron scintillator detector, and in the case of a copper activated zinc sulfide (ZnS: Cu) phosphor, it is used for neutron radiography.

^As a neutron scintillator using ¹⁰ B as a converter, a ZnS: Ag phosphor and ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ) are mixed and then sintered at a temperature of 500 ° C. or higher. / ¹⁰ B ₂ O ₃ translucent neutron scintillator has been developed and used in neutron image detectors (Non-patent Document 2 and Patent Document 1). The raw material ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ) changes to ¹⁰ B ₂ O ₃ during sintering.

A ZnS / H ₃ ¹⁰ BO ₃ translucent neutron scintillator using an epoxy resin as an adhesive has been developed for neutron radiography (Non-patent Document 3). The amount of epoxy resin as an adhesive is 25% of the total weight.

On the other hand, as a transparent scintillator capable of increasing the thickness of the scintillator, it is commercially available glass scintillator containing ⁶ Li ⁽⁶ Li glass scintillator) have been widely used conventionally. This scintillator has a major feature that the decay time is as short as 100 ns, which is about a quarter of that of a ZnS / ⁶ LiF translucent neutron scintillator, and has very little afterglow. It is used. However, this glass scintillator has high gamma ray sensitivity, and it has been difficult to use it in a place where the gamma ray background is high.

  Improvement of neutron scattering research in neutron image detectors using neutron scintillators used in neutron scattering experiments at pulsed neutron research facilities using accelerators such as J-PARC in Japan, ISIS in the UK, and SNS in the United States In addition, with the increase in accelerator output, neutron imaging measurement at a high count rate in a high gamma ray background is required.

  As will be described later, in the sintering method, the fluorescent spectrum of the phosphor shifts due to the high temperature during sintering, and there is a problem that the thickness becomes non-uniform due to the generation of bubbles and the position resolution deteriorates. Is difficult to produce. In the adhesive method, since the refractive indexes of the three materials of the neutron converter, the ZnS phosphor, and the adhesive are different from each other, the fluorescence transmittance is also reduced, and the detection performance as a neutron scintillator cannot be ensured. Furthermore, the detection efficiency for thermal neutrons is low.

JP 2005-200461 A

Nulcl. Instr. And Meth. 75 (1969) 35-42 Nucl. Instr. & Meth., A529 (2004) 325-328 Physics Procedia 43 (2013) 216-222

  An object of the present invention is to provide a neutron scintillator capable of performing neutron imaging measurement at a high count rate in a high gamma ray background and a method for manufacturing the neutron scintillator.

  The present invention also provides a method for producing a neutron scintillator that can produce a very thin scintillator by making use of the detection characteristics of a ZnS phosphor that has a short decay time, little afterglow, and low sensitivity to gamma rays. Objective.

  The present inventors considered that a translucent neutron scintillator using a ZnS-based phosphor having low sensitivity to gamma rays is useful for solving the problems, and as a result of intensive studies, the present invention has been completed.

The basis of the present invention is the development of a substance having a large proportion containing ¹⁰ B and having adhesiveness. As a result of conducting various experiments using ¹⁰ B concentrated boric acid as a basic material, ¹⁰ B concentrated boric acid, a modified alicyclic polyamine of an epoxy curing agent, and water, ethyl alcohol, methyl alcohol, a mixture of water and ethyl alcohol, Alternatively, when a mixture of water and methyl alcohol was mixed, a chemical reaction that polymerized and became a transparent and adhesive substance could be found. It was found that a translucent ZnS / ¹⁰ B converter neutron scintillator can be manufactured by using this ¹⁰ B-containing adhesive substance as a neutron converter and adhesive, mixing with a ZnS: Ag phosphor and applying it to a scintillator substrate.

Further, it was confirmed that the ¹⁰ B-containing adhesive substance solidifies when dried, but cracks may occur after a while. In the case of a thin neutron scintillator, it was found that cracking does not occur by adding a blending medium that is commercially available and used as a medium to delay the drying of watercolor paints and then solidifying. In the case of a neutron scintillator with a thickness of 50 μm or more, ¹⁰ B concentrated boric acid having a ¹⁰ B isotope concentration of 90% or more and a modified alicyclic polyamine are mixed and reacted completely to be polymerized to be transparent ¹⁰ When the amount of the modified alicyclic polyamine is reduced with respect to the amount of B-concentrated boric acid, the amount of the modified alicyclic polyamine is 60% to 20% with respect to the amount necessary for the transparency. In addition, it was found that cracking does not occur by using a cloudy ¹⁰ B-containing translucent adhesive substance in a state where ¹⁰ B concentrated boric acid is not completely dissolved as a neutron converter and adhesive.

In the present invention, an adhesive substance containing ¹⁰ B is used as a neutron converter / adhesive, and a ZnS: Ag phosphor is mixed and then applied to an aluminum substrate or the like, so that ZnS / H using a conventional adhesive is used. Provided is a technology for producing a semi-transparent neutron scintillator with a ZnS / ¹⁰ B neutron converter having a practical short-term detection efficiency and a short short decay time and a long decay time that could not be realized by ₃ ¹⁰ BO ₃ translucent neutron scintillator .

According to the present invention, the following aspects are provided.
^[1] and ¹⁰ B isotope concentration of 90% or more of the ¹⁰ B enriched boric acid _{^{(H 3}} 10 BO ^3), a curing agent for modified cycloaliphatic polyamine, a modified aliphatic polyamine or an aliphatic diamine composed primarily, To prepare a ¹⁰ B-amine mixture,
A ¹⁰ B-containing transparent adhesive substance is prepared by mixing water, ethyl alcohol, methyl alcohol, a mixture of water and ethyl alcohol or a mixture of water and methyl alcohol with the ¹⁰ B-amine mixture,
To the ¹⁰ B containing transparent adhesive material, a mixture of ZnS-based phosphor, ZnS-based phosphor ^{- 10} B containing a transparent adhesive material was prepared,
The ZnS-based phosphor - a ^{10 B} containing a transparent adhesive material is applied and dried onto a substrate, wherein the solidifying method translucent ZnS / 10 ^B converter neutron scintillator.
[2] The curing agent is mixed in a weight ratio of 0.04 times or more and 1 time or less with respect to the ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ). A method for producing a translucent ZnS / ¹⁰ B converter neutron scintillator.
[3] The translucent ZnS / ¹⁰ B converter neutron scintillator according to [1] or [2], wherein a solidification retarder is further mixed when preparing the ¹⁰ B-containing transparent adhesive material. Production method.
[4] The ZnS-based phosphor is mixed at a weight ratio of 1 to 3 times with respect to the ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ) [1] to [3] translucent ZnS ^{/ 10} method for producing B converter neutron scintillator according to any one of the.
[5] The translucent film according to any one of [1] to [4], further comprising coating the surface of the translucent ZnS / ¹⁰ B converter neutron scintillator with a water-resistant transparent film or a water-resistant transparent coating material. A method for producing a ZnS / ¹⁰ B converter neutron scintillator.
[6] The ZnS phosphor according to any one of [1] to [5], which is a silver-activated zinc sulfide phosphor (ZnS: Ag) having an alpha ray detection ratio of 0.35 to 1. A method for producing a translucent ZnS / ¹⁰ B converter neutron scintillator.
[7] Translucent manufactured by the method according to any one of [1] to [6] and including a substrate and a mixed layer of ¹⁰ B-containing transparent adhesive substance and ZnS phosphor on the substrate. ZnS / ¹⁰ B converter neutron scintillator.

The translucent ZnS / ¹⁰ B converter neutron scintillator of the present invention has low sensitivity to gamma rays, and can perform neutron imaging measurement at a high count rate in a high gamma ray background.

Since the method for producing a translucent ZnS / ¹⁰ B converter neutron scintillator of the present invention does not include sintering, the fluorescence spectrum does not shift to the long wavelength side, and nonuniformity in thickness due to generation of bubbles may occur. In addition, a very thin scintillator can be manufactured by taking advantage of the detection characteristics of a ZnS phosphor having a short decay time and little afterglow.

  A neutron scintillator used for a neutron image detector of a neutron scattering experimental apparatus is required to have low sensitivity to gamma rays. In order to lower the gamma-ray sensitivity as compared with the conventional ZnS phosphor / neutron converter scintillator, it is preferable to lower the gamma-ray sensitivity of the ZnS phosphor itself. A ZnS: Ag phosphor having low gamma ray sensitivity is used as the ZnS phosphor. According to the manufacturing method of the present invention, the decay time of the ZnS: Ag phosphor essential for high count rate measurement and the afterglow can be reduced, so that neutron image detection with high counting efficiency can be simultaneously performed.

Furthermore, although ⁶ Li as a neutron converter is expensive, ¹⁰ B concentrated boric acid used as a neutron converter in the present invention is 1/10 or less the price of ⁶ Li, and can realize a significant cost reduction.

Is a graph showing the correlation between the ⁶ LiF neutron converter samples and ^{10 B} a short decay time and the total amount of fluorescence enriched boric acid neutron converter samples. Of ⁶ LiF neutron converter samples and ^{10 B} enriched boric acid neutron converter sample is a graph showing the correlation of the long decay time and the total amount of fluorescence. It is a flowchart of the manufacturing method of this invention used in the Example. In Example 1, it is a graph showing the ^{10 B} containing transparent adhesive permeability material samples 1 to 3 wavelengths is normalized the value of 700nm as 1. In Example 1, it is a graph which shows the fluorescence spectrum of the ZnS: Ag fluorescent substance for particle beam detection, and the fluorescence intensity of P11 type ZnS: Ag, Cl fluorescent substance. In Example 1, the neutron signal waveforms of two types of semi-transparent ZnS / ¹⁰ B converter neutron scintillators obtained by measuring 2000 signals and averaging these signals and the conventional AST Co., Ltd. ZnS / ⁶ LiF translucent scintillator It is a graph which shows a neutron signal waveform. In Example 1, it is a graph which shows the frequency distribution of the number of photons of two types of translucent ZnS / 10B converter neutron scintillators of this invention, and a commercially available AST scintillator. It is a graph which shows the relationship between the addition amount of 80 minute hardening | curing agent, and detection efficiency. It is a graph which shows the relationship between the additive ratio of an 80-minute hardening | curing agent when the addition amount which becomes transparent of an 80-minute hardening | curing agent is 1, short decay time, and long decay time. It is a graph showing the relationship between the added amount and the detection efficiency for ^{10 B} enriched boric acid ZnS phosphor. Amount for ^{10 B} enriched boric acid ZnS phosphor and is a graph showing the relationship between the short decay time and long decay time. It is a graph which shows each fluorescence spectrum of alpha ray irradiation, gamma ray irradiation, and alpha ray sensitive of the ZnS fluorescent substance for particle beam detection whose alpha ray detection ratio is 0.51.

Preferred embodiment

The method for producing the translucent ZnS / ¹⁰ B converter neutron scintillator of the present invention includes:
^{(1) 10} B isotope concentration of 90% or more of the ¹⁰ B enriched boric acid with _{^{(H 3}} 10 BO ^3), a curing agent for modified cycloaliphatic polyamine, a modified aliphatic polyamine or an aliphatic diamine composed primarily, To prepare a ¹⁰ B-amine mixture,
(2) The ¹⁰ B-amine mixture is mixed with water, ethyl alcohol, methyl alcohol, a mixture of water and ethyl alcohol or a mixture of water and methyl alcohol to prepare a ¹⁰ B-containing transparent adhesive substance,
(3) to the ¹⁰ B containing transparent adhesive material, a mixture of ZnS-based phosphor, ZnS-based phosphor ^{- 10} B containing a transparent adhesive material was prepared,
(4) the ZnS-based phosphor - a ^{10 B} containing a transparent adhesive substance, characterized in that solidifying dried coating on the substrate.

The ZnS-based phosphor is preferably mixed at a weight ratio of 1 to 3 times with respect to the ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ).

  The ZnS phosphor is preferably a silver activated zinc sulfide phosphor (ZnS: Ag) having low sensitivity to gamma rays. In particular, a silver activated zinc sulfide phosphor (ZnS: Ag) having an alpha ray detection ratio of 0.35 to 1 is preferable. In this ZnS: Ag phosphor, the decay time and afterglow of the ZnS: Ag phosphor, which are indispensable for high count rate measurement, are reduced, so that it is possible to simultaneously detect neutron images with high counting efficiency.

  The alpha ray detection ratio is that when alpha rays are irradiated, fluorescence is emitted over 320 nm to 580 nm, and the peak wavelength is 395 nm to 410 nm, and the alpha ray sensitive fluorescence spectrum and gamma rays or electron rays are emitted. In the ZnS: Ag phosphor for particle beam detection showing a synthesized fluorescence spectrum, a gamma-ray-irradiated fluorescence spectrum corresponding to a fluorescence spectrum having a peak wavelength of 435 nm to 450 nm in a fluorescence spectrum ranging from 380 nm to 560 nm emitted from It means the ratio of the intensity of the alpha-sensitive fluorescent spectrum to the intensity of the total fluorescent spectrum (corresponding to the alpha-irradiated spectrum) obtained by adding the sensitive fluorescent spectrum and the gamma-irradiated fluorescent spectrum. In the ZnS phosphor shown in FIG. 12, the alpha ray detection ratio is 0.51 from the alpha ray irradiation fluorescence spectrum, the gamma ray irradiation fluorescence spectrum, and the alpha ray sensitive fluorescence spectrum of the particle beam detection ZnS phosphor.

  As the curing agent, a commercially available transparent curing agent mainly composed of a modified alicyclic polyamine, a modified aliphatic polyamine or an aliphatic diamine can be used. Examples of modified alicyclic polyamines include isophorone diamine, mensendiamine, N-aminoethylpiverazine, modified aliphatic polyamines include diethylaminopropylamine, tetraethylenepentamine, and aliphatic diamines as 2-methylpentapentamine. Preferable examples include methylene diamine and diethylenetriamine.

Curing of the epoxy resin with an amine-based curing agent reacts with the active hydrogen of the primary amine and the epoxy group to produce a secondary amine, and the secondary amine reacts with the epoxy group and cures. In the case of the present invention, it is considered that the epoxy curing agent modified alicyclic polyamine and ¹⁰ B concentrated boric acid chemically reacted to form a slightly cloudy adhesive substance. However, since this semi-transparent adhesive substance does not have fluidity, it is very difficult to mix with a ZnS: Ag phosphor to form a translucent ZnS / ¹⁰ B converter neutron scintillator. For this reason, water, methyl alcohol, ethyl alcohol, a mixed solution of water and methyl alcohol, or a mixed solution of water and ethyl alcohol is added to the solid adhesive material to obtain a transparent and liquid ¹⁰ B-containing adhesive material. To do.

The addition amount of the curing agent varies depending curing agent, it is preferable to mix with the ¹⁰ B enriched boric acid _{^{(H 3}} 10 BO ³⁾ 1 times the weight 0.04 times or more relative to. A suitable amount of the curing agent necessary to obtain a transparent and liquid ¹⁰ B-containing adhesive substance is 0.2 to 1 times the ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ). It is a weight ratio. For example, in the case of a commercially available transparent modified alicyclic polyamine as a transparent curing agent, 0.9 times, in the case of a commercially available 80 minute curing agent (modified alicyclic polyamine), 0.52 times, 20 minute curing agent ( In the case of (modified aliphatic polyamine), it can be added in a weight ratio of 0.3 times, and in the case of aliphatic diamine, it can be added in a weight ratio of 0.2 times. If the amount of the curing agent is too large, cracks may occur in the translucent ZnS / ¹⁰ B converter neutron scintillator. In this case, the amount of the curing agent is the same as that of the ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃₎ 20% to 60% of the amount needed to completely transparent when mixed, i.e. 0.04-fold relative to the ¹⁰ B enriched boric acid _{^{(H 3}} 10 BO ³⁾ ~ It is preferable to mix 0.6 times the amount and use in a cloudy state.

When preparing the ¹⁰ B-containing transparent adhesive substance, it is preferable to further mix a solidification retarder. By adding a solidification retarder, the solidification of the ¹⁰ B-containing transparent adhesive substance can be delayed to uniformly disperse the ZnS phosphor particles. A commercially available aqueous blending medium is preferred as the solidification retarder. The addition amount of the solidifying retarder is preferably 0.2 to 0.4 times that of the ¹⁰ B-amine mixture.

Furthermore, it is preferable to coat the surface of the translucent ZnS / ¹⁰ B converter neutron scintillator with a water-resistant transparent film or a water-resistant transparent coating material.

  As the substrate, a substrate usually used for a neutron scintillator can be used without limitation, and an aluminum substrate, a titanium substrate, a float glass substrate, and a quartz glass substrate can be suitably used. Since the glass substrate containing boric acid captures neutrons, a glass substrate containing no boric acid is preferable.

In the present invention, a translucent ZnS / ¹⁰ B converter neutron scintillator including a substrate and a mixed layer of a ¹⁰ B-containing transparent adhesive substance and a ZnS phosphor on the substrate is obtained by the above-described manufacturing method. The translucent ZnS / ¹⁰ B converter neutron scintillator of the present invention has a practical level of detection efficiency that cannot be realized by a conventional adhesive type neutron scintillator, and achieves a short short decay time and a long decay time.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[Combination of ZnS phosphor and neutron converter]
The ZnS / ⁶ LiF translucent neutron scintillator that has been widely used for many years and the ZnS / ¹⁰ B ₂ O ₃ translucent neutron scintillator produced by sintering were examined in detail for detection characteristics against thermal neutrons.

A Nichia 1109-041 phosphor having the same performance as P11 (alpha ray detection ratio: 0.29), which is a conventional ZnS: Ag phosphor, was used, and a ZnS / ⁶ LiF translucent neutron scintillator and ZnS / ¹⁰ A B ₂ O ₃ translucent neutron scintillator was fabricated. The mixing ratios of ZnS phosphor, neutron converter ⁶ LiF and ¹⁰ B ₂ O ₃ are 2: 1 and 1: 1, respectively.

7.4 GBq of ²⁴¹ Am-Li was used as a neutron beam source, and the detection characteristics of the two were compared using thermal neutrons produced by decelerating with a paraffin block. As a result, despite using the same ZnS: Ag phosphor, the ZnS / ⁶ LiF translucent neutron scintillator has a short decay time of 0.429 μs and a long decay time of 2.76 μs, and ZnS / ¹⁰ B ₂ O The short decay time of the ₃ translucent neutron scintillator was 0.324 μs, and the long decay time was 2.32 μs. There is a significant difference between the short decay time and the long decay time between the ZnS / ⁶ LiF translucent neutron scintillator and the ZnS / ¹⁰ B ₂ O ₃ translucent neutron scintillator, and both decays using the ¹⁰ B ₂ O ₃ neutron converter It turns out that time also becomes short. The short decay time and long decay time used here are defined as follows. It is said that the decay time corresponding to a short component of the ZnS: Ag phosphor is 1 μs or less, so that the value corresponds to 0.632 times (corresponding to 1−e ⁻¹ ) of the total signal voltage obtained by integration up to 1 μs. The elapsed time when the integrated signal voltage reached was defined as “short decay time”. The elapsed time when the integral signal voltage reached a value corresponding to 0.632 times the total signal voltage obtained by integrating up to 8 μs of the decay time of the long component hitting the afterglow was defined as “long decay time”.

In spite of using the same phosphor, the cause of the difference in the decay time between the ZnS / ⁶ LiF translucent neutron scintillator and the ZnS / ¹⁰ B ₂ O ₃ translucent neutron scintillator was investigated.

In the ZnS / ⁶ LiF translucent neutron scintillator, the nuclear reaction between ⁶ Li and neutrons n + ⁶ Li-> ³ H + α
The ^{3 H} and alpha rays emitted ZnS by: detecting at Ag phosphor is performed neutron detection. On the other hand, in the ZnS / ¹⁰ B ₂ O ₃ translucent neutron scintillator, the nuclear reaction between ¹⁰ B and neutrons n + ¹⁰ B-> ⁷ Li + α
⁷ Li and alpha rays emitted by the above are detected by a ZnS: Ag phosphor and neutron detection is performed.

  In both cases, the emitted particle beam is different, and the emission rate and the released energy are also different. For this reason, the following experiment was performed on the assumption that the decay time varies depending on the type of particle beam emitted as the factor that has the greatest influence on the decay time physically.

⁶ LiF is ground to an average particle size of 3 μm and ¹⁰ B concentrated boric acid is ground to an average particle size of 1.6 μm. The concentration of ⁶ Li as an isotope was 90%, and the concentration of ¹⁰ B concentrated boric acid as an isotope was 96%. After applying a Nitoms double-sided tape on a microscope cover glass (size: 18 mm x 18 mm, thickness 0.15 mm), ⁶ LiF powder and ¹⁰ B concentrated boric acid powder were respectively applied to one side of the double-sided tape. Two types of neutron converter samples each coated with approximately one layer of ⁶ LiF and ¹⁰ B concentrated boric acid were prepared. On the other hand, as a ZnS: Ag phosphor, a conventional type 1109-041ZnS phosphor manufactured by Nichia Corporation is used, and ZnS: Ag phosphor particles are coated almost on one side of a double-sided tape by the same method. An Ag sample was prepared.

The sample surfaces of the neutron converter sample and the ZnS: Ag sample are arranged facing each other, and the glass substrate surface of the ZnS: Ag sample is attached to the photomultiplier tube. A 7.4 GBq ²⁴¹ Am-Li radiation source was used as the neutron radiation source, and after decelerating with a paraffin block having a thickness of 5 cm, the neutron converter sample was irradiated. R1924A manufactured by Hamamatsu Photonics was used as the photomultiplier tube, and it was used at an applied voltage of 1000V. The obtained alpha ray fluorescence signal was collected using a Letroy LT344 oscilloscope. The collection conditions were set at a vertical sensitivity of 100 mV / div, a time sensitivity of 1 μs / div, a trigger level of 32 mV, and a sampling frequency of 500 MHz. 2000 signals were measured, these signals were analyzed, and a short decay time, a long decay time and a total fluorescence amount of each time were obtained for one signal.

The correlation between the short decay time and the total fluorescence amount of the ⁶ LiF neutron converter sample and the ¹⁰ B enriched borate neutron converter sample is shown in FIG. 1, and the correlation between the long decay time and the total fluorescence amount is shown in FIG. ^In the case of the ⁶ LiF neutron converter sample, it was found that both the short decay time and the long decay time were divided into two different decay times and total fluorescence correlations. In addition, in the case of the ¹⁰ B enriched borate neutron converter sample, it was found that both the short decay time and the long decay time showed substantially the same correlation as the correlation of the shorter decay time in the case of the ⁶ LiF neutron converter sample. From prior experiments using alpha rays, it has been found that the correlation with the shorter decay time is due to alpha rays. Therefore, the correlation with the longer decay time in ⁶ LiF is n + ⁶ Li−> ³ H + α.
It was found to be due to ³ H (triton) released in the reaction.
In the case of a ¹⁰ B concentrated borate neutron converter sample, n + ¹⁰ B-> ⁷ Li + α
⁷ Li released by the reaction is considered to be indistinguishable because it has a close correlation with alpha rays.

From these results, when ⁶ LiF is used as a neutron converter, the emitted triton increases the short decay time and the long decay time, which is an index of the afterglow component, and the high count rate measurement of scintillator neutron detection It was confirmed that this was a factor that deteriorated the multi-count characteristic (the ratio at which one or more signals are output from the neutron detector even though only one neutron is incident). Therefore, it was found that the short decay time and the long decay time can be shortened by using a ¹⁰ B neutron converter that does not emit Triton. It was also found that the short decay time and the long decay time can be further improved by combining the particle beam detection ZnS: Ag phosphor with a short decay time and a long decay time with a ¹⁰ B neutron converter.

[Problems of the sintering method]
A sintered ZnS / ¹⁰ B ₂ O ₃ translucent neutron scintillator was manufactured using a ZnS: Ag phosphor for particle beam detection instead of the conventional ZnS: Ag phosphor, and its detection characteristics were measured. As a result, when sintering at 500 ° C. or higher, which is close to the melting point of ¹⁰ B ₂ O ₃ , the fluorescence spectrum of the particle beam detection ZnS: Ag phosphor shifts to the longer wavelength side, and the particle beam detection ZnS: Ag phosphor. It was found that it was impossible to make use of the original detection characteristics of.

On the other hand, another major use of neutron scintillators is as a screen for neutron radiography. Attempts have been made at home and abroad to observe the internal state of a fuel cell or the like with a radiography apparatus having a positional resolution of about 10 μm. However, when a conventional ZnS / ⁶ LiF translucent neutron scintillator is used, 30 μm It is very difficult to realize the following position resolution. The reason for this is that when ⁶ LiF is used as a neutron converter, the range of Triton released by the capture reaction with neutrons is 30 μm or more, so the emission point of fluorescence is widened, and even if ideally measured, 30 μm The following position resolution cannot be obtained. For this reason, if a ZnS / ¹⁰ B ₂ O ₃ translucent neutron scintillator manufactured by sintering is used as a scintillator using a ¹⁰ B neutron converter with a short range, each of the emitted alpha rays and ⁷ Li will fly. There is a possibility that a position resolution of 10 μm can be obtained as short as 9 μm and 4 μm. However, it is extremely difficult to reduce the thickness of the scintillator because it is extremely difficult to ensure the uniformity of the thickness when viewed microscopically due to the generation of bubbles of ¹⁰ B ₂ O ₃ during sintering. Cannot be obtained.

[Problems of the adhesive method]
^{When the 10} B neutron converter is used, the ranges of alpha rays and ⁷ Li emitted by the neutron capture reaction are as short as 9 μm and 4 μm, respectively. For this reason, the powdery ¹⁰ B enriched borate neutron converter or ¹⁰ B ₂ O ₃ neutron converter and ZnS: Ag phosphor were mixed with an adhesive by the same method as the method for producing the ZnS / ⁶ LiF translucent neutron scintillator. Later, when it is manufactured by coating on a substrate, the emitted fluorescence of ⁷ Li is hardly emitted, and the amount of fluorescence at the time of generation is reduced by half.

A ZnS / H ₃ ¹⁰ BO ₃ translucent neutron scintillator was fabricated using an organic adhesive. As the ZnS phosphor, a conventionally used P11 type ZnS: Ag phosphor, 1109-041 ZnS phosphor manufactured by Nichia Corporation, is used, and the weight ratio of the phosphor to ¹⁰ B concentrated boric acid is 2: 1. Using. As an organic adhesive, SU Premium [Soft] manufactured by Konishi Co., Ltd., which is a silylated urethane resin adhesive, was used and an amount of 8% of the total weight was added.

As a result of measuring the detection efficiency of the ZnS / H ₃ ¹⁰ BO ₃ translucent neutron scintillator for thermal neutrons, it was found to be 9.1% (Applied scintillation technologies) ZnS / ⁶ LiF translucent neutron commercially available from the UK. Only about one third of the detection efficiency of the scintillator was obtained.

[Example]
According to the flow shown in FIG. 3, ¹⁰ B concentrated boric acid having a ¹⁰ B isotope concentration of 90% or more, a modified alicyclic polyamine, and water, ethyl alcohol, methyl alcohol, a mixture of water and ethyl alcohol, or water and methyl After mixing and polymerizing a mixture of alcohols, ¹⁰ B-containing transparent adhesive material prepared by adding and mixing blending medium as a curing retarder was used as a neutron converter and adhesive, and a ZnS: Ag phosphor and A translucent ZnS / ¹⁰ B converter neutron scintillator produced by mixing will be described.

^{As 10} B concentrated boric acid, 96% ¹⁰ B concentrated boric acid manufactured by Stella Chemifa Co., Ltd. was used. This ¹⁰ B concentrated boric acid was pulverized and the average particle size was 1.6 μm. Used in the examples.

[Example 1]
As the modified alicyclic polyamine of the epoxy curing agent, an 80 minute curing agent and a transparent curing agent, which are modified alicyclic polyamine type curing agents for the main agent Z-1 manufactured by Nissin Resin Co., Ltd., were used. The main raw material of the 80-minute curing agent and the transparent curing agent is isophorone diamine. Their main performance is shown in Table 1.

In terms of weight ratio, ¹⁰ B concentrated boric acid is 1 and 0.52 in the case of 80-minute curing agent and 0.9 in the case of transparent curing agent, and both are cured with ¹⁰ B concentrated boric acid. The amount of water more than 0.2 times the amount of the added agent was added, ultrasonic waves were applied to accelerate the polymerization reaction, and a transparent ¹⁰ B-containing adhesive substance colored slightly yellow was obtained. It remains liquid, but only have a little colored yellow and solidify over time, almost transparent ^{10 B} containing a transparent adhesive material was obtained.

^In order to evaluate the performance of ¹⁰ B-containing adhesive substance such as the transmittance, ¹⁰ mg of ¹⁰ B concentrated boric acid and 520 mg of 80-minute curing agent were put in four ceramic crucibles with a capacity of 30 cc, respectively, and then 800 mg of water, Blending medium made by Windsor & Newton, which is used to delay the drying of watercolor paints after adding, mixing and polymerizing three solvents of 400 mg and 400 mg of methyl alcohol and 400 mg of water and 400 mg of ethyl alcohol. 400 mg of each was added and mixed to prepare three types of transparent ¹⁰ B-containing adhesive substances. In the polymerization, a W-113 type ultrasonic cleaner (frequency 45 kHz, output 100 W) manufactured by Honda Electronics Co., Ltd. was used to accelerate the polymerization reaction by ultrasonic waves for 10 minutes. All of the obtained ¹⁰ B-containing adhesive substances had a very light yellow color. 80 mg of these ¹⁰ B-containing adhesive substances were applied to a 18 mm × 18 mm × 0.15 mm (thickness) glass plate and dried to obtain samples 1 to 3 for measuring transmission characteristics.

The transmittances of these three types of ¹⁰ B-containing transparent adhesive material samples 1 to 3 were measured using a Hitachi spectrophotometer U-3300. Values normalized by setting the value at a wavelength of 700 nm to 1 were plotted (FIG. 4). Water and a mixture of water and methyl alcohol show substantially the same transmission characteristics, the transmittance gradually decreases from around 500 nm, and is about 0.7 at 360 nm corresponding to the rising wavelength of the fluorescence spectrum of the ZnS: Ag phosphor. It became. On the other hand, for the liquid mixture of water and ethyl alcohol, the method of decreasing the transmittance from around 480 nm was further slow, and even at 360 nm, it was 0.8 (decrease rate of 20%), indicating the best transmission characteristics. The results are summarized in Table 2.

Therefore, after mixing and polymerizing ¹⁰ B concentrated boric acid 500 mg, 80-minute curing agent 260 mg, water 200 mg and methyl alcohol 200 mg in a pottery crucible having a capacity of 30 cc, blending medium manufactured by Windsor & Newton 200 mg of each was added and mixed to prepare a transparent ¹⁰ B-containing adhesive substance. After adding 400 mg of water to the ¹⁰ B-containing transparent adhesive substance and mixing, 1250 mg of two types of ZnS: Ag phosphors described below are added and mixed to form an aluminum substrate of 5 cm × 5 cm × 0.3 mm (thickness). It was applied, dried and solidified to produce translucent ZnS / ¹⁰ B converter neutron scintillator samples 4-5.

  The ZnS: Ag phosphor used in Sample 4 is a particle beam detection ZnS: Ag phosphor having an alpha ray detection ratio of 0.51. The color of the phosphor is very light brown. The ZnS: Ag phosphor used in Sample 5 is a 1109-041 phosphor manufactured by Nichia Corporation, which is a P11 type phosphor. The color of the phosphor is white.

  A ZnS: Ag phosphor for particle beam detection having an alpha ray detection ratio of 0.51 was manufactured by the following process.

For 50 g of zinc sulfide having a center particle size of 8 μm, silver nitrate corresponding to 0.015% of the weight of zinc sulfide, lithium chloride corresponding to 6% of the weight of zinc sulfide, and 0.12 of the weight of zinc sulfide. % Of strontium sulfide corresponding to% was added, 20 cc of distilled water was added and mixed, and then dried. Graphite crucible (outside is 60 mmφ, length is 50 mm, inside is 30 mmφ, bottom thickness is 10 mm, top lid thickness is 10 mm, volume for material is 30 mmφ, length is 30 mm, center of top lid is The dried calcined material was put into a 1 mmφ hole for releasing a part of the sublimate generated from the calcined material in (1), and then the upper lid was closed, and the product was fired in an electric furnace. An electric furnace KDF-S70 type manufactured by Denken Co., Ltd. was used as the electric furnace. Firing was performed under the following conditions.
Firing temperature: 820 ° C
Cover gas: Firing time of flowing CO ₂ at 2 liters / minute: 2 hours After the fired sintered product was powdered, it was washed with water to obtain a ZnS: Ag phosphor for particle beam detection.

The fluorescence characteristics of the ZnS: Ag phosphor for particle beam detection with respect to alpha ray irradiation and gamma ray irradiation were examined. Samples for measuring fluorescence characteristics were coated with Nitoms double-sided tape on a microscope cover glass (size: 18 mm x 18 m, thickness 0.15 mm) and then coated with powder of ZnS: Ag phosphor for particle beam detection on one side. did. By this operation, almost one layer of ZnS: Ag phosphor particles can be applied to one side of the double-sided tape. When this method is used, the measurement error with respect to the amount of fluorescence (integrated value of the fluorescence intensity of the fluorescence spectrum) with respect to irradiation with alpha rays is ± 10%.
The measurement sample was placed at the sample position of the excitation light irradiation system of the fluorometer, and the fluorescence spectrum was measured by alpha ray irradiation and gamma ray irradiation.

  In addition, the measurement of the fluorescence spectrum obtained by irradiating the alpha ray and the gamma ray described in the present invention was performed under the equipment and conditions shown below.

A spectrofluorimeter F-2500 manufactured by Hitachi, Ltd. was used as a measuring device, and the measurement was performed with the fluorescent slit fixed at 20 nm. A ²⁴¹ Am alpha source (diameter: 5 mmφ, source intensity: about 1 MBq) manufactured by Amersham, UK is used as a radiation source for alpha radiation, and the same ²⁴¹ Am alpha radiation source is used for gamma radiation. An alpha ray shield consisting of four aluminum foils (thickness 12 μm) was attached to (diameter 5 mmφ, radiation source strength: about 1 MBq), and 60 gV gamma rays were irradiated.

  The obtained fluorescence spectrum obtained by normalizing the alpha-ray-irradiated fluorescence spectrum of the obtained ZnS: Ag phosphor added with 0.12% strontium sulfide and the gamma-ray-irradiated fluorescence spectrum obtained by gamma-ray irradiation with the maximum value as 1, respectively. Then, by subtracting the gamma ray irradiation fluorescence spectrum from the alpha ray irradiation fluorescence spectrum, an alpha ray sensitive fluorescence spectrum was obtained, and these three types of fluorescence spectra obtained are shown in FIG.

  From FIG. 12, an alpha-sensitive fluorescence spectrum having a peak wavelength of 395 nm to 410 nm in a fluorescence spectrum of 320 nm to 580 nm emitted when irradiated with alpha rays, and 380 nm emitted when irradiated with gamma rays or electron beams. In a silver activated zinc sulfide (ZnS: Ag) phosphor for particle beam detection showing a synthesized fluorescence spectrum, a gamma ray sensitive fluorescence spectrum corresponding to a fluorescence spectrum having a peak wavelength of 435 nm to 450 nm in a fluorescence spectrum extending up to 560 nm The intensity ratio (alpha ray detection ratio) of the gamma ray sensitive fluorescence spectrum was 0.51 with respect to the intensity of the total fluorescence spectrum obtained by adding the alpha ray sensitive fluorescence spectrum and the gamma ray sensitive fluorescence spectrum.

As a result of measuring the thickness of the manufactured translucent ZnS / ¹⁰ B converter neutron scintillator samples 4 to 5, it was about 350 μm.

For translucent ZnS ^{/ 10} B converter neutron scintillator samples 4-5, using a Am-Li-ray source 7.4GBq as neutron sources, it was measured detection characteristics with thermalized in paraffin blocks 5cm thickness.

A pulse signal obtained when a neutron was irradiated to a semi-transparent neutron scintillator of a ZnS / ¹⁰ B neutron converter was measured with an oscilloscope, and the detection characteristics for neutrons were measured. A neutron signal was detected by placing a photomultiplier tube on one side of the scintillator sample. R1924A manufactured by Hamamatsu Photonics was used as the photomultiplier tube, and it was used at an applied voltage of 1000V. The obtained neutron fluorescence signal was subjected to waveform data collection using an LT344 type oscilloscope manufactured by LeCroy. The collection conditions were set at a vertical sensitivity of 100 mV / div, a time sensitivity of 1 μs / div, a trigger level of 32 mV, and a sampling frequency of 500 MHz. The neutron signal waveforms of two types of semi-transparent ZnS / ¹⁰ B converter neutron scintillators obtained by measuring 2000 signals and averaging these signals are shown together with the neutron signal waveforms of conventional AST ZnS / ⁶ LiF translucent scintillators. It is shown in FIG. While the neutron signal waveform of the sample 4 using the ZnS phosphor for particle beam detection: Ag rapidly decreases after 1 μs, the scintillator sample 5 using the conventional P11 type ZnS phosphor: Ag slowly decreases. You can see that it is influenced by afterglow. However, the effect of the afterglow is about half that of the AST ZnS / ⁶ LiF translucent scintillator using the same conventional P11 type ZnS phosphor: Ag, and the ¹⁰ B neutron converter has ⁶ It was confirmed that the influence of afterglow on the Li neutron converter was reduced.

In addition, the detection efficiency for thermal neutrons is determined by examining the time stamp recorded at the time of acquisition of each pulse signal waveform and obtaining the number of pulse signal waveforms acquired within a certain period of time to derive the count rate first. It was determined by performing counting rate and relative comparison of the known ⁶ Li glass scintillator. The detection efficiency of the scintillator sample 4 using the ZnS: Ag phosphor for particle beam detection was 22.8%, and the detection efficiency of the scintillator sample 5 using the P11 type ZnS: Ag phosphor was 22.3%.

In order to investigate the influence of afterglow based on the obtained signal, the fluorescence lifetime characteristics were analyzed. Since it is said that the decay time corresponding to a short component of ZnS: Ag phosphor is 1 μs or less, the value corresponds to 0.632 times (corresponding to 1-e ⁻¹ ) of the total signal voltage obtained by integrating up to 1 μs. The elapsed time when the integrated signal voltage reached is defined as the short decay time. Further, a value obtained by converting an average integrated signal voltage of 1 pulse or 1 μs of a pulse neutron signal into a photon number of fluorescence was defined as an average photon number of 1 μs or an average photon emission amount of 8 μs. The decay time of the long component that hits the afterglow is a long decay of the elapsed time when the integrated signal voltage reaches 0.632 times the total signal voltage obtained by integration up to 8 μs (corresponding to 1-e ⁻¹ ). Defined as time.

United Kingdom which is a semi-transparent ZnS / ¹⁰ B converter neutron scintillator sample 5 of the present invention using a P11 type ZnS: Ag phosphor and a conventional ZnS / ⁶ LiF translucent scintillator similarly using a P11 type ZnS: Ag phosphor. The short decay time and the long decay time of the AST scintillator are compared. The translucent ZnS / ¹⁰ B converter neutron scintillator of the present invention had a short decay time of 0.39 μs and a long decay time of 2.31 μs. In contrast, the short decay time of the British AST scintillator was 0.44 μs and the long decay time was 2.84 μs. In comparison, the translucent ZnS / ¹⁰ B converter neutron scintillator of the present invention improved with a short decay time of 88% and a long decay time of 80%.

On the other hand, the translucent ZnS / ¹⁰ B converter neutron scintillator sample 4 using the particle beam detecting ZnS: Ag phosphor had a short decay time of 0.26 μs and a long decay time of 1.26 μs. Compared with the conventional AST scintillator, the translucent ZnS / ¹⁰ B converter neutron scintillator using the ZnS: Ag phosphor for particle beam detection has a large decay time of 60% and a long decay time of 44%. It was found that it was improved.

In addition, since the total signal voltage obtained by integrating up to 1 μs is proportional to the amount of fluorescence emitted during the time of 1 μs, the total signal voltage of the ⁶ Li glass scintillator in which the photon emission amount is known in advance is used. The number of photons was obtained for each neutron signal. Using the obtained number of photons, the translucent ZnS: ¹⁰ B converter neutron scintillator sample 5 of the present invention using a P11-type ZnS: Ag phosphor and the translucent of the present invention using a ZnS: Ag phosphor for particle beam detection are used. FIG. 7 shows a comparison of three photon number distributions of a ZnS / ¹⁰ B converter neutron scintillator sample 4 and a commercially available AST ZnS / ⁶ LiF translucent neutron scintillator. From this result, although the scintillator of sample 4 and the scintillator of sample 5 have a peak in a region where the number of photons is slightly smaller than that of the conventional AST scintillator, almost the same photon number distribution can be obtained. I understood.

Furthermore, the average photon emission amount of 1 μs is 24000 photons / pulse in the conventional AST scintillator, whereas the translucent ZnS / ¹⁰ B converter using the ZnS: Ag phosphor for particle beam detection of the present invention. The neutron scintillator was 16000 photons / pulse and the translucent ZnS / ¹⁰ B converter neutron scintillator sample 5 of the present invention using P11 type ZnS: Ag phosphor was 17000 photons / pulse. ^Since the average photon emission amount of the ⁶ Li glass scintillator is 6000 photons / pulse, it was found that a sufficient emission amount can be obtained.

Regarding the detection efficiency, short decay time and long decay time of translucent ZnS / ¹⁰ B converter neutron scintillator sample 4 using ZnS: Ag phosphor for particle beam detection, the weight ratio of ¹⁰ B concentrated boric acid and 80 minute curing agent We investigated the changes caused by. The detection efficiency was plotted in FIG. 8, and the short decay time and long decay time were plotted in FIG.

[Example 2]
As another example using a modified alicyclic polyamine, an example of producing a translucent ZnS / ¹⁰ B converter neutron scintillator for a screen with a very small thickness of 15 μm used for high-position resolution neutron radiography will be described.

After adding 260 mg of 80-minute curing agent to 500 mg of ¹⁰ B concentrated boric acid, a mixed solution of 200 mg of water and 200 mg of methyl alcohol was added as a solvent and mixed to prepare a transparent ¹⁰ B-containing adhesive substance. In the polymerization, the polymerization reaction was promoted by ultrasonic waves for 10 minutes using an ultrasonic cleaner. This ¹⁰ B-containing adhesive substance was diluted with a mixture of 1200 mg of water and 1200 mg of methyl alcohol, and then mixed with ZnS: Ag, Al phosphor, half of which was 10 cm × 10 cm × 0.3 mm (thickness). A translucent ZnS / ¹⁰ B converter neutron scintillator was manufactured by applying to an aluminum substrate, drying and solidifying. The ZnS: Ag, Al phosphor has about 1.4 times the amount of fluorescence with respect to the emitted alpha rays compared to the commercially available P11 type ZnS: Ag, Cl phosphor. In this example, a 1109-149 phosphor manufactured by Nichia Corporation having an average particle size of 2.5 μm, which is as small as possible, was used. After solidification, the thickness of the translucent ZnS / ¹⁰ B neutron converter neutron scintillator was measured and found to be 15 μm thick. The scintillator did not crack even after 6 months.

This semi-transparent ZnS ^{/ 10} B converter neutron scintillator, with Am-Li-ray source 7.4GBq as neutron sources, were measured detection characteristics with thermalized in paraffin blocks 5cm thickness. About the characteristic measuring method, the same method as Example 1 was used and the detection efficiency with respect to a neutron and the total discharge | release amount of a photon were calculated | required. The total amount of photons emitted was determined as the product of the detection efficiency and the number of photons obtained in the time up to 8 μs. As a result, the detection efficiency was 5%, and the total photon emission amount was 2700 photons. The detection efficiency of ZnS / ⁶ LiF translucent neutron scintillator manufactured by AST in the UK that has been commercially available worldwide is 30.4%, and the total emission amount of photons is 14500 photons. Despite the scintillator of 15 μm and about 1 / 30th the thickness of a British AST scintillator, the detection efficiency is about 1/6, and the total photon emission is about 1/6. I understood.

[Example 3]
An example in which a modified aliphatic polyamine is used in place of the modified alicyclic polyamine will be described.

  As the modified aliphatic polyamine, a 20 minute curing agent which is a modified aliphatic polyamine type curing agent for the main agent Z-1 manufactured by Nissin Resin Co., Ltd. was used. Table 1 shows the main specifications of the hardener.

After mixing and polymerizing ¹⁰ B concentrated boric acid 500 mg, 20-minute curing agent 150 mg, water 200 mg and methyl alcohol 200 mg in a pottery crucible with a capacity of 30 cc, 200 mg of Windsor &Newton's blending medium was added. A transparent ¹⁰ B-containing adhesive material was prepared by mixing. In the polymerization, the polymerization reaction was promoted by ultrasonic waves for 10 minutes using an ultrasonic cleaner. This ^{10 B} containing transparent adhesive material exhibited extremely thin red.

After diluting the ¹⁰ B-containing adhesive substance with 400 mg of water, 1250 mg of ZnS: Ag phosphor was added and mixed, then applied to an aluminum substrate of 5 cm × 5 cm × 0.3 mm (thickness), dried and solidified. A semi-transparent ZnS / ¹⁰ B converter neutron scintillator was fabricated. As the ZnS phosphor, as in Example 1, a ZnS: Ag phosphor for particle beam detection having an alpha ray detection ratio of 0.51 was used.

This semi-transparent ZnS ^{/ 10} B converter neutron scintillator, with Am-Li-ray source 7.4GBq as neutron sources, were measured detection characteristics with thermalized in paraffin blocks 5cm thickness. About the characteristic measuring method, the same method as Example 1 was used. As a result, the detection efficiency was 25.2%, and the average photon emission amount at 1 μs was 18000 photons / pulse.

[Example 4]
An example in which an aliphatic diamine is used in place of the modified alicyclic polyamine will be described. As the aliphatic diamine, 2-methyl pentamethylene diamine manufactured by Danish Struers was used.

After mixing and polymerizing ¹⁰ B concentrated boric acid 500 mg, aliphatic diamine 130 mg, water 200 mg and ethyl alcohol 200 mg in a 30 cc pottery crucible, 200 mg each of Windsor &Newton's blending medium was added and mixed. A transparent ¹⁰ B-containing adhesive material was prepared. In the polymerization, the polymerization reaction was promoted by ultrasonic waves for 10 minutes using an ultrasonic cleaner. The color of the ^{10 B-containing} transparent adhesive material was clear.

This ¹⁰ B-containing adhesive substance is diluted with 400 mg of water, and 1250 mg of ZnS: Ag phosphor is added and mixed. After that, a half amount is applied to an aluminum substrate of 5 cm × 5 cm × 0.3 mm (thickness) and dried. Solidified to produce a translucent ZnS / ¹⁰ B converter neutron scintillator. As the ZnS phosphor, the particle beam detection ZnS: Ag phosphor having the alpha ray detection ratio described above of 0.51 was used.

This ZnS ^{/ 10} B neutron converter translucent neutron scintillator, with Am-Li-ray source 7.4GBq as neutron sources, were measured detection characteristics with thermalized in paraffin blocks 5cm thickness. About the characteristic measuring method, the same method as Example 1 was used and the detection efficiency with respect to neutrons and the average photon emission amount were obtained. The detection efficiency was 28.2%, the average photon emission amount of 1 μs was 18000 photons / pulse. The detection property is good because the weight of the aliphatic diamine polymerized with ¹⁰ B concentrated boric acid to become transparent is very small, 50% of the weight of the modified alicyclic polyamine,
n + ¹⁰ B-> ⁷ Li + α
⁷ Li and alpha rays emitted by the reaction is considered that since the light emission has increased, especially the average range is due to a very short ⁷ Li.

  The results of Example 3 and Example 4 are summarized in Table 4.

[Example 5]
^{10 B} isotope concentration of 90% or more of the ^{10 B} enriched boric acid, modified cycloaliphatic polyamines, and a mixture of water and ethyl alcohol were mixed, fully reacted polymerized ¹⁰ was set to transparent ^B concentrated after prepared by reducing the amount of modified cycloaliphatic polyamine relative to the amount of boric acid, using the ^{10 B} containing translucent adhesive material prepared by mixing the addition of blending medium as a neutron converter and adhesives, ZnS: Ag A translucent ZnS / ¹⁰ B converter neutron scintillator prepared by mixing with a phosphor, applying to a substrate, drying and solidifying will be described.

^{As 10} B concentrated boric acid, 96% ¹⁰ B concentrated boric acid manufactured by Stella Chemifa Co. was used, and the ¹⁰ B concentrated boric acid was pulverized, and the average particle size was 1.6 μm. For the modified alicyclic polyamine of the epoxy curing agent, an 80 minute curing agent which is a modified alicyclic polyamine type curing agent for the main agent Z-1 manufactured by Nissin Resin Co., Ltd. was used.

Two ceramic ceramic crucibles with a capacity of 30 cc, ¹⁰ B concentrated boric acid 500 mg and 208 mg and 182 mg corresponding to 0.8 and 0.7 times the amount of 80-minute curing agent that becomes transparent after reaction are added and mixed to polymerize. After that, 200 mg each of Windsor &Newton's blending medium used for delaying the drying of the watercolor paint was added and mixed to produce two types of transparent ¹⁰ B-containing adhesive substances. In the polymerization, a W-113 type ultrasonic cleaner (frequency 45 kHz, output 100 W) manufactured by Honda Electronics Co., Ltd. was used to accelerate the polymerization reaction by ultrasonic waves for 10 minutes. Any ¹⁰ B-containing translucent adhesive material that was made was slightly white and cloudy.

Each ¹⁰ B-containing translucent adhesive substance is diluted with 400 mg of water, 1250 mg of ZnS: Ag phosphor is added and mixed, then applied to an aluminum substrate of 5 cm × 5 cm × 0.3 mm (thickness), dried and solidified. Then, semi-transparent ZnS / ¹⁰ B converter neutron scintillator samples 6 to 7 were produced. As the ZnS phosphor, a particle beam detection ZnS: Ag phosphor having an alpha ray detection ratio of 0.51 was used. In these two scintillators, a slight crack in the groove occurred after two months.

For two types of translucent ZnS / ¹⁰ B converter neutron scintillator samples 6 and 7 with the amount of hardener 0.8 times and 0.7 times, an Am-Li ray source 7.4 GBq is used as a neutron source, and a paraffin block The detection characteristics were measured by thermal neutronization at a thickness of 5 cm. About the characteristic measuring method, the same method as Example 1 was used and the detection efficiency with respect to a thermal neutron and short decay time and long decay time were calculated | required. As a result, the detection efficiencies of the two types of translucent ZnS / ¹⁰ B converter neutron scintillators with the amount of curing agent 0.8 times and 0.7 times are 21.1% for sample 6 and 21.9 for sample 7 respectively. %Met.

For the detection efficiency, short decay time, and long decay time of ZnS / ¹⁰ B neutron converter translucent neutron scintillator using ZnS: Ag phosphor for particle beam detection, the weight ratio of ¹⁰ B concentrated boric acid to 80 minute curing agent In order to investigate the change due to the above, the amount of curing agent for 80 minutes was 0.8 and 0.7, the detection efficiency was plotted in FIG. 8, and the short decay time and long decay time were plotted in FIG.

[Example 6]
^{10 B} isotope concentration of 90% or more of the ^{10 B} enriched boric acid, modified cycloaliphatic polyamines, and a mixture of water and ethyl alcohol were mixed, fully reacted polymerized ¹⁰ was set to transparent ^B concentrated The amount of modified alicyclic polyamine with respect to the amount of boric acid was reduced from 60% to 20%, mixed and reacted, then blended with a blending medium and mixed with ¹⁰ B-containing translucent adhesive substance produced by neutron A translucent ZnS / ¹⁰ B converter neutron scintillator that is used as a converter and adhesive, mixed with a ZnS: Ag phosphor, applied to a substrate, dried and solidified will be described.

^{As 10} B concentrated boric acid, 96% ¹⁰ B concentrated boric acid manufactured by Stella Chemifa Co. was used, and the ¹⁰ B concentrated boric acid was pulverized, and the average particle size was 1.6 μm. For the modified alicyclic polyamine of the epoxy curing agent, an 80 minute curing agent which is a modified alicyclic polyamine type curing agent for the main agent Z-1 manufactured by Nissin Resin Co., Ltd. was used.

In 5 pottery pots of 30 cc, ¹⁰ B concentrated boric acid 500 mg, the amount of 80-minute curing agent that becomes transparent after reaction, 260 mg 0.6 times, 0.5 times, 0.4 times, 0.3 times and 0 Made by Windsor & Newton, which is used to delay the drying of watercolor paints after adding 156 mg, 130 mg, 104 mg, 78 mg and 52 mg equivalent to 2 times, and mixing and polymerizing each mixture of water 200 mg and ethyl alcohol 200 mg. 200 mg of each blending medium was added and mixed to produce 5 types of transparent ¹⁰ B-containing adhesive materials. In the polymerization, a W-113 type ultrasonic cleaner (frequency 45 kHz, output 100 W) manufactured by Honda Electronics Co., Ltd. was used to accelerate the polymerization reaction by ultrasonic waves for 10 minutes. Any ¹⁰ B-containing translucent adhesive material thus produced became white and cloudy.

Each ¹⁰ B-containing translucent adhesive substance was diluted with 400 mg of water, 1250 mg of ZnS: Ag phosphor was added and mixed, and then half the amount was applied to an aluminum substrate of 5 cm × 5 cm × 0.3 mm (thickness). Drying and solidification produced semi-transparent ZnS / ¹⁰ B converter neutron scintillator samples 8-13. As the ZnS phosphor, a particle beam detection ZnS: Ag phosphor having an alpha ray detection ratio of 0.51 was used. These five scintillators did not crack even after 6 months.

About 5 kinds of ZnS / ¹⁰ B neutron converter translucent neutron scintillator with the amount of hardener from 0.6 times to 0.2 times, using Am-Li ray source 7.4 GBq as neutron source, paraffin block 5 cm thickness The detection characteristics were measured using thermal neutrons. About the characteristic measuring method, the same method as Example 1 was used and the detection efficiency with respect to a thermal neutron and short decay time and long decay time were calculated | required. As a result, the detection efficiencies of the five types of semi-transparent ZnS / ¹⁰ B converter neutron scintillators with the amount of curing agent ranging from 0.6 times to 0.2 times are 21.2%, 21.5%, and 21.7, respectively. %, 19.1% and 18.2%.

Regarding the detection efficiency, short decay time, and long decay time of the ZnS / ¹⁰ B neutron converter translucent neutron scintillator using the ZnS: Ag phosphor for particle beam detection shown above, ¹⁰ B concentrated boric acid and 80-minute curing are used. In order to examine the change due to the weight ratio of the agent, the amount of the 80-minute curing agent was set to 0.6, 0.5, 0.4, 0.3 and 0.2, and the detection efficiency is shown in FIG. Time and long decay time are plotted in FIG.

Here, the results of the detection efficiency, the short decay time, and the long decay time of Examples 1 to 6 will be summarized with reference to FIGS. 8 and 9. FIG. 8 shows the change in detection efficiency for thermal neutrons by changing the 80-minute curing agent ratio from 1 to 0.2. When the weight ratio of the 80-minute curing agent is 1, the detection efficiency is the best because the transparency is high. Thereafter, when the weight ratio is lowered, the concentrated boric acid is not completely dissolved, and the ¹⁰ B-containing adhesive substance becomes cloudy. Therefore, the fluorescence generated by the neutron capture reaction of ¹⁰ B is reduced and the transparency is also lowered. Therefore, the detection efficiency is lowered. However, as described in the means for solving the problems, the translucent ZnS / H ₃ ¹⁰ BO ₃ neutron scintillator manufactured using a conventional organic adhesive has a detection efficiency for thermal neutrons of 9.1%. From these results, it was found that each detection efficiency can be secured twice or more.

In addition, in FIG. 9 showing the weight ratio dependence of the hardener between the short decay time and the long decay time, the transparency is good when the ratio of the 80-minute hardener is 1, so that both the short decay time and the long decay time are different from each other. It is shorter than It can also be confirmed that both the short decay time and the long decay time become longer because the transparency decreases as the ratio of the 80-minute curing agent decreases. However, while the long decay time showing the afterglow effect of the scintillator manufactured by AST, which is a conventional translucent ZnS / ⁶ LiF neutron scintillator, is 2.82 μs, the translucent ZnS / ¹⁰ B converter neutron of the present invention The long decay time of the scintillator was very short, less than half, confirming that the afterglow effect was halved.

[Example 7]
For the semi-transparent ZnS / ¹⁰ B converter neutron scintillator in which the ratio of the 80-minute curing agent described in Example 6 is 0.5, the weight of the ZnS phosphor to be mixed is ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ). A translucent ZnS / ¹⁰ B converter neutron scintillator with a ratio of 1: 1 to 3: 1 with respect to the weight of the neutron scintillator will be described.

6 ceramics crucibles with a capacity of 30 cc, ¹⁰ B concentrated boric acid 500 mg, a mixture of 80 mg 80-minute curing agent that is 0.5 times the amount of 80-minute curing agent that becomes transparent after reaction, and 200 mg of water and 200 mg of ethyl alcohol In addition, after mixing and polymerizing, 200 mg each of Windsor &Newton's blending medium used to delay the drying of the watercolor paint was added and mixed to prepare six transparent ¹⁰ B-containing adhesive substances. Add 500 mg, 750 mg, 1000 mg, 1250 mg, 1500 mg and 1750 mg as the above-described ZnS: Ag phosphor for particle beam detection to each ¹⁰ B-containing translucent adhesive substance, further dilute with 400 mg water and mix well. Half of the amount was applied to an aluminum substrate of 5 cm × 5 cm × 0.3 mm (thickness), dried and solidified to produce six types of translucent ZnS / ¹⁰ B converter neutron scintillator samples 13-18. The ratio of ZnS: Ag phosphor for particle beam detection to 500 mg of ¹⁰ B concentrated boric acid was 1: 1, 1.5: 1, 2: 1, 2.5: 1, 3: 1 and 3.5: 1, respectively. It hits.

About these six types of semi-transparent ZnS / ¹⁰ B converter neutron scintillators, Am-Li radiation source 7.4 GBq was used as a neutron radiation source, thermal neutronization was performed with a paraffin block thickness of 5 cm, and detection characteristics were measured. About the characteristic measuring method, the same method as Example 1 was used and the detection efficiency with respect to a thermal neutron and the short decay time and long decay time were calculated | required, respectively.

The figure shows the change in the detection efficiency of a semitransparent neutron scintillator for ZnS / ¹⁰ B neutron converter when the ratio of ZnS: Ag phosphor for particle beam detection to 500 mg of ¹⁰ B concentrated boric acid is changed from 1: 1 to 3.5: 1. 10 shows. As a result, it was found that the detection efficiency for thermal neutrons was 18.1% with the ratio of 2: 1. In the case of 3.5: 1, since the adhesive material was reduced, the adhesive ability was reduced and cracking occurred.

  Similarly, the dependency of the short decay time and the long decay time on the ratio of the ZnS: Ag phosphor for particle beam detection is shown in FIG. As a result, since the transparency is good when the weight ratio is 1, the short decay time and the long decay time are the shortest, and thereafter the short decay time is obtained when the weight ratio is from 1.5: 1 to 3.5: 1. It can be seen that the long decay time becomes longer at almost the same rate. It is considered that the transparency deteriorates when the amount of the ZnS: Ag phosphor for particle beam detection increases.

Summarizing the above results, it can be seen that the ratio of the ZnS: Ag phosphor for particle beam detection to ¹⁰ B concentrated boric acid is 1: 1 to 3: 1, and good detection characteristics are exhibited.

[Example 8]
In order to protect the surface of the translucent ZnS / ¹⁰ B converter neutron scintillator from moisture, a transparent film having a water resistant function is laminated on the surface of the translucent ZnS / ¹⁰ B converter neutron scintillator and the translucent ZnS / ¹⁰ A water-resistant treatment example in which a transparent coating agent having a water-resistant function is applied to the surface of the B converter neutron scintillator will be described.

The ¹⁰ B-containing translucent adhesive material of the present invention has a property of dissolving in water. For this reason, when used as a translucent ZnS / ¹⁰ B converter neutron scintillator, it is necessary to have a water resistance function in order to protect the surface from moisture.

^{As 10} B concentrated boric acid, 96% ¹⁰ B concentrated boric acid manufactured by Stella Chemifa Co. was used, and the ¹⁰ B concentrated boric acid was pulverized, and the average particle size was 1.6 μm. For the modified alicyclic polyamine of the epoxy curing agent, an 80 minute curing agent which is a modified alicyclic polyamine type curing agent for the main agent Z-1 manufactured by Nissin Resin Co., Ltd. was used.

Polymerize by adding 500 mg of ¹⁰ B concentrated boric acid, 130 mg, which is 0.5 times the amount of 80-minute curing agent that becomes transparent after reaction, and 200 mg of water and 200 mg of ethyl alcohol to a pottery crucible with a capacity of 30 cc. Then, 200 mg each of Windsor &Newton's blending medium used for delaying the drying of the watercolor paint was added and mixed to prepare a transparent ¹⁰ B-containing adhesive substance. In the polymerization, a W-113 type ultrasonic cleaner (frequency 45 kHz, output 100 W) manufactured by Honda Electronics Co., Ltd. was used to accelerate the polymerization reaction by ultrasonic waves for 10 minutes.

This ¹⁰ B-containing translucent adhesive substance was diluted with 400 mg of water, and 1250 mg of the above-described ZnS: Ag phosphor for particle beam detection with an alpha ray detection ratio of 0.51 was added and mixed well. Two semi-transparent ZnS / ¹⁰ B converter neutron scintillators were fabricated by applying to a 5 cm × 0.3 mm (thickness) aluminum substrate, drying and solidifying.

One of the two translucent ZnS / ¹⁰ B converter neutron scintillators produced was subjected to a water-resistant treatment that was laminated on the surface of the scintillator. A laminate film having a thickness of 30 μm was used. As a laminator, LPD3212 type manufactured by Fuji Plastics Co., Ltd. was used. ZnS ^{/ 10} B after sandwiching an aluminum substrate with a laminate film of a neutron converter coated 5cm × 5cm × 0.3mm (thickness), processing the laminating speed under the condition of 140 mm / min to set the lamination temperature to 140 ° C. Went.

  Comparing the detection efficiency for thermal neutrons before and after laminating treatment, it is 21.2% before treatment and 20.9% after treatment, and the statistical error is ± 0.4%. It was confirmed that the detection efficiency was not deteriorated by the processing.

Next, another semi-transparent ZnS / ¹⁰ B converter neutron scintillator was subjected to a water resistance treatment in which a transparent coating agent having a water resistance function was applied to the surface. The transparent coating agent used was Nikko Terios Coat NP-360QD, which is a room temperature glass coating agent. The solvent used in this coating agent is isopropyl alcohol. Since isopropyl alcohol did not function as a solvent for the reaction between ¹⁰ B concentrated boric acid and modified alicyclic polyamine, it was selected because it did not melt the surface of the manufactured neutron converter translucent neutron scintillator.

After the opposite surface of the substrate was protected with a masking tape, a translucent ZnS / ¹⁰ B converter neutron scintillator was dipped in a stock solution of Terios Coat NP-360QD manufactured by Nikko, and then lifted vertically, thoroughly shaken off the stock solution and dried. After drying, the masking tape was peeled off, and the thickness of the applied coating agent was measured by measuring the thickness before and after the coating treatment. As a result, it was found that the thickness of the coating agent by this coating method was 40 to 50 μm. After the treatment, the water resistance was confirmed by immersing in water. As a result, it was confirmed that the water resistance function was ensured by completely repelling water.

  In addition, when comparing before and after waterproofing treatment with the coating agent, 19.9% before treatment and 20.0% after treatment, and the statistical error is ± 0.4%. It was confirmed that the detection efficiency was not deteriorated even by processing.

Claims (6)

And ¹⁰ B isotope concentration of 90% or more of the ¹⁰ B enriched boric acid _{^{(H 3}} 10 BO ^3), modified cycloaliphatic polyamine, a curing agent and modified aliphatic polyamine or an aliphatic diamine and main material, were mixed ¹⁰ B-amine mixture
A ¹⁰ B-containing transparent adhesive substance is prepared by mixing water, ethyl alcohol, methyl alcohol, a mixture of water and ethyl alcohol or a mixture of water and methyl alcohol with the ¹⁰ B-amine mixture,
To the ¹⁰ B containing transparent adhesive material, a mixture of ZnS-based phosphor, ZnS-based phosphor ^{- 10} B containing a transparent adhesive material was prepared,
The ZnS-based phosphor - a ^{10 B} containing a transparent adhesive material is applied and dried onto a substrate, wherein the solidifying method translucent ZnS / 10 ^B converter neutron scintillator. The translucent ZnS according to claim 1, wherein the curing agent is mixed in a weight ratio of 0.04 times or more and 1 time or less with respect to the ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ). / ^{10 A} method for producing a B converter neutron scintillator. The method for producing a translucent ZnS / ¹⁰ B converter neutron scintillator according to claim 1, wherein a solidification retarder is further mixed when the ¹⁰ B-containing transparent adhesive substance is prepared. The ZnS-based phosphor is mixed in a weight ratio of 1 to 3 times with respect to the ¹⁰ B concentrated boric acid (H ₃ ¹⁰ BO ₃ ). translucent ZnS ^{/ 10} method for producing B converter neutron scintillator according. Furthermore, comprising coating the surface of the translucent ZnS / 10 ^B converter neutron scintillator with waterproof transparent film or water-resistant transparent coating material, semi-transparent ZnS / 10 ^B converter as claimed in any one of claims 1 to 4 A method for manufacturing a neutron scintillator. The translucent ZnS / ^{10 according} to any one of claims 1 to 5, wherein the ZnS-based phosphor is a silver-activated zinc sulfide phosphor (ZnS: Ag) having an alpha ray detection ratio of 0.35 to 1. B converter neutron scintillator manufacturing method .