JP5522566B2 - Radioisotope production method and apparatus - Google Patents

Description

In the present invention, radioactive isotopes used for radiodiagnostics and the like are used as radioactive wastes composed of a wide range of isotopes (for example, strontium 90 to cesium 137) having a high intensity and a long half-life without using nuclear fuel material ²³⁵ U. The present invention relates to a manufacturing method and an apparatus which can be generated efficiently and inexpensively without generating a large amount and enable stable supply.

  At present, in the medical field, radiation and radioisotopes (radioisotopes; hereinafter also referred to as RI) are indispensable for diagnosing and treating diseases. Radiation emitted from RI can be reliably detected and quantified even if the amount of the substance itself is very small, and examination and diagnosis are performed by scintigraphy using this property. The pharmaceutical used for this is called a so-called “radiopharmaceutical”, and the RI used for the radiopharmaceutical or the like is suitable to emit a gamma ray having a short half-life and a large permeability.

Examples of RI used for radiopharmaceuticals and examples of use thereof include, for example, ^99m Tc for brain / thyroid / bone scintigraphy, ⁶⁷ Ga for breast cancer / lung cancer / malignant lymphoma treatment, ²⁰¹ Tl for parathyroid gland / tumor / myocardium Scintigraphy, ⁶⁰ Co is a gamma knife radiation source, ³² P is leukemia treatment, ³⁵ S is DNA base sequence / gene chromosome arrangement determination, ⁵¹ Cr is measurement of circulating blood volume / recirculating red blood cell volume, ⁵⁹ Fe is binding to total iron in serum (TIBC) measurement, ⁸⁹ Sr, ¹⁵³ Sm, ¹⁸⁶ Re for pain relief, ⁹⁰ Y for malignant lymphoma treatment, ¹⁰³ Pd for prostate cancer treatment, ¹²⁵ I for tumor marker, ¹³¹ I for hyperthyroidism and thyroid cancer treatment ¹³³ Xe is a local lung ventilation function test, etc.

Of these RIs, ^99m Tc, ⁹⁰ Y, ¹³¹ I, and ¹³³ Xe are currently fissioned by neutron irradiation in a nuclear reactor using highly enriched ²³⁵ U enriched with ²³⁵ U from 36% to 93%. It is manufactured by reacting and extracting RI from its fission products. This method of using enriched ²³⁵ U is particularly problematic from the viewpoint of non-proliferation, and the International Atomic Energy Agency (IAEA) and others are working to switch to technologies that use low-enriched raw materials with a ²³⁵ U enrichment of 20% or less. The technology development corresponding to it is advanced all over the world. However, despite 30 years of work, most RIs in the world are still produced using highly enriched ²³⁵ U. On the other hand, when low-concentration ²³⁵ U with a ²³⁵ U enrichment of 20% or less is used as a raw material for RI production, a new problem arises that the amount of plutonium produced increases about 25 times. Therefore, the target RI is irradiated with thermal neutrons (0.025 eV) from the reactor, such as ⁶⁰ Co, ³² P, ³⁵ S, ⁵¹ Cr, ⁵⁹ Fe, ⁸⁹ Sr, ¹⁵³ Sm, and ¹⁸⁶ Re, and the generated RI is extracted. Methods are also being used. A method of irradiating a target with charged particles from a cyclotron, such as ⁶⁷ Ga, ²⁰¹ Tl, ¹⁰³ Pd, and ¹²⁵ I, is also used.

Some RIs are manufactured in Japan, but most of them rely on imports from overseas. However, in 2007, it became difficult to obtain radiopharmaceuticals because of a problem with a Canadian reactor. In August 2008, a Dutch reactor supplying approximately 26% of ⁹⁹ Mo to the global market stopped operation due to partial corrosion deformation of the bottom structure of the primary cooling system, and started operation in mid-February 2009. It was resumed. However, in May 2009, a heavy water leak was detected again in a Canadian reactor, and the operation was halted. The recovery is considered to be early as of the end of March 2010. In this way, if most of RI is relied on by imports from other countries, it is expected that a stable supply system cannot be maintained due to domestic circumstances in other countries, aging of reactors, maintenance, troubles, etc., and stable supply of RI Has become an important and urgent issue. In particular, in Canada, where Japan relies on imports of most RIs, it is expected that the nuclear reactors for the supply will reach the operation permit deadline in 2011. There is no realistic plan from a long-term perspective. In the United States and Europe, the stable supply of RI including ⁹⁹ Mo is eagerly awaited, but a realistic system that can cope with it has not been taken, and it is necessary to establish the system as soon as possible ( Non-patent document 1). In addition, if most of RI is dependent on imports from overseas, the price of RI used in medical treatments will rise, and this will cause a rise in overall medical costs. In 2007, the sales price of radiopharmaceuticals reached 44 billion yen (Non-patent Document 2: Page 5).

In addition, when ²³⁵ U is fissioned in a nuclear reactor, various nuclides are generated in addition to the desired RI as shown in FIG. 1 (Non-Patent Document 3), and storage, management, processing, etc. of unnecessary nuclear waste are generated. Became enormous and very annoying.

In consideration of such problems, the present applicants have, ²³⁵ without using a ^U, efficiently producing a highly radioactive molybdenum ^{99 Mo} which is the parent nuclide of radioactive technetium ^{99m Tc,} which is often used as a radioactive diagnostic agent The technique which performs is proposed (patent document 1). In the proposed method, an aqueous Mo solution in which a Mo compound is dissolved in water is irradiated with neutrons in an irradiation capsule installed in the core of a nuclear reactor to generate ⁹⁹ Mo by a ⁹⁸ Mo (n, γ) reaction. It is intended to produce ⁹⁹ Mo efficiently by recovering Mo aqueous solution continuously or batchwise. Likewise Patent Document 2, using a ^{98 Mo,} a technique for generating radioactive molybdenum ^{99 Mo} by thermal neutron capture reaction is proposed. However, in the case of using these thermal neutron capture reactions, since the reactor is used, the production site is limited, and in addition to being largely dependent on the operation mode of the reactor, the production cost is expensive and the reaction cross section is small. The specific activity was low and there was a problem in production efficiency. In addition, considering the safety of nuclear reactors, for example, there may be a situation where it is necessary to stop the operation for half a year, for example, during periodic inspections. In order to easily and stably supplying the ^{99 Mo} facilities such as hospitals these circumstances, it was necessary further technical devices.

  On the other hand, it is also performed to generate a RI by irradiating a raw material target with a proton or heavy ion beam using an accelerator. In the case of protons, by making the accelerator used compact, it can be easily used in facilities such as hospitals. However, when generating RI using protons emitted from such a small accelerator, it can only cope with RI of light nuclides, and avoiding enlargement of the accelerator when trying to cope with RI of heavy nuclides. There was a problem that could not. That is, when generating a RI using protons, the proton has a positive charge, so to react with the target nucleus of a heavy nuclide (although it is a nucleus with many positively charged protons) Because there is a repulsive interaction between positive charges, we have to overcome this and get inside the nucleus. For that purpose, the energy of the incident protons needs to be sufficiently high. Furthermore, when protons are incident on the target material, the proton energy in the target is greatly reduced, so that the thickness of the target that can be used is limited, and as a result, the efficiency of generating sufficient RI is often not high. On the other hand, the energy loss in the target increases the temperature of the target, and the use intensity of the proton beam may be limited for a target having a low melting point. By the way, the proton beam is generated by an accelerator and transported through the vacuum pipe to a nearby location where the target is set. However, when the target is set on the atmosphere side, it is necessary to maintain the vacuum in the vacuum pipe and shut off the atmosphere side portion. The material used for blocking is required to be as thin as possible in order to suppress a decrease in the energy and intensity of the proton beam. However, if this material is continuously irradiated with a proton beam, it is destroyed as a result of radiation damage, and it becomes difficult to use a high-intensity proton beam for a long time. In order to manufacture various RI according to the purpose, if the target material can be set in the atmosphere, the shape and material of the target can be selected flexibly, which is practically very convenient. However, as described above, RI generation using a proton beam has a problem. These circumstances are similar for heavy ion beams. The problem is greater than the amount of positive charges more than protons.

JP 2008-102078 A Special Table 2002-504231

“Accelerating production of medical isotopes” Nature Vol 457, 29 January 2009 Science Council of Japan Basic Medical Committee / General Engineering Committee Meeting Task Review Subcommittee on Radioactive and Radioactive Utilization “Proposal: Stable Supply System of Radioisotopes in Japan” July 24, 2008 Nuclear Physics A462 (1987) 85-108 North-Holland, Amsterdam

The present invention solves the above-mentioned problems of the prior art, does not use the enrichment ²³⁵ U, does not use the nuclear reactor facility, and does not generate a large amount of radioactive waste, and can be efficiently and inexpensively and simply. It is an object of the present invention to provide a method and an apparatus capable of realizing a stable supply of a radioisotope.

  In order to solve the above problems, the present invention provides the following technical methods or means.

[1] power supply for applying a voltage to accelerate the charged particle beam consisting of deuterium or protons, the voltage from the power supply is applied, an acceleration tube for accelerating the charged particle beam, and, provided on the accelerator exit section Rutotomoni, is arranged fast neutron generator target of titanium occluding tritium, with fast neutron generator which the charged particle beam accelerated in this occurs the fast neutron irradiated, (i) below ( In the case of (n, 2n) reaction, the value (unit: MeV) obtained by adding 0.5 MeV to the (n, 2n) reaction threshold is set as the lower limit, and the reaction of (n, 2n) reaction at an energy value other than the lower limit Within the range where the cross-sectional area is equal to the upper limit of the energy value that is equal to the reaction cross-sectional area of the (n, 2n) reaction at the lower limit, (ii) in the case of the following (n, p) reaction, The threshold for the gas source target The value obtained by multiplying the atomic number (Z) by 0.10 [unit: MeV / number of protons] and 0.2 [unit: MeV] [unit: MeV] is set as the lower limit, and the lower limit. (Iii) The following (n, p) is within the range where the reaction cross-sectional area of the (n, p) reaction at an energy value other than the value is equal to the upper limit of the energy cross-section of the (n, p) reaction at the lower limit In the case of (np) reaction, the number obtained by multiplying the threshold of (n, np) reaction by atomic number (Z) of the gas source target by 0.10 [unit: MeV / number of protons] and 0.2 A value obtained by adding [unit: MeV] [unit: MeV] as a lower limit, and a reaction cross section of (n, np) reaction at an energy value other than the lower limit is (n, np). Within the range where the energy value equal to is the upper limit, (iv) (n, n ') below In the case of reaction, (n, n ′) reaction threshold value (unit: MeV) obtained by adding 0.15 MeV to the reaction threshold is set as the lower limit, and (n, n ′) reaction interruption at an energy value other than the lower limit. using a scale small accelerator enough to Ru to generate fast neutrons with the energy value in the range of area is the (n, n ') limit the energy value equal to the cross sections of the reaction in the lower limit value,
The fast neutrons are generated by the charged particle beam irradiation, irradiated to the gas material target encapsulating sample container, depending on the type of gas raw material target to cause one of the following reactions to produce radioactive isotopes A method for producing a radioisotope characterized by the above.
(1) (n, 2n) reaction: reaction that releases two neutrons by irradiation of one neutron (2) (n, p) reaction: reaction that releases one proton by irradiation of one neutron (3) (n, np) reaction: reaction that releases one neutron and one proton by irradiation of one neutron (4) (n, n ') reaction: incident neutron by irradiation of one neutron Reaction that emits one neutron of energy different from the energy of

[1] In the first aspect, and characterized in that the gas raw material target comprises one or more target nuclei in the following Table 1, (n, 2n) to cause a reaction to produce a radioactive isotope A method for producing radioisotopes.

[3] In the first invention, the gas source target includes one or a plurality of target nuclei in Table 2 below , and a (n, p) reaction is caused to generate a radioisotope. A method for producing radioisotopes.

[4] In the first invention, the gas source target includes one or a plurality of target nuclei in Table 3 below , and a (n, np) reaction is caused to generate a radioisotope. A method for producing radioisotopes.

[5] A method for producing a radioisotope according to the first invention, wherein the gas source target is ¹²⁹ Xe, and a (n, n ′) reaction is caused to generate a radioisotope.

[6] In any of the above aspects to first to fifth, fast in a state in which a sample container enclosing the gas raw material target is the fast neutron generator in a state of being adhered to or spaced provided to the accelerator exit section A method for producing a radioisotope, which comprises irradiating a gas source target with neutrons.

[7] power source for applying a voltage to accelerate the charged particle beam consisting of deuterium or protons, the voltage from the power supply is applied, an acceleration tube for accelerating the charged particle beam, and, that is provided to the accelerator exit section together, tritium is disposed a fast neutron generator target of occluded titanium, with fast neutron generator which the charged particle beam is accelerated to generate a fast neutron irradiated, (i) below (n , 2n) In the case of a reaction, the value obtained by adding 0.5 MeV to the (n, 2n) reaction threshold [unit: MeV] is set as the lower limit, and the reaction interruption of the (n, 2n) reaction at an energy value other than the lower limit Within the range where the upper limit is the energy value equal to the reaction cross-sectional area of the (n, 2n) reaction at the lower limit value, (ii) in the case of the following (n, p) reaction, the (n, p) reaction threshold value The gas source target Value obtained by multiplying atomic number (Z) by 0.10 [unit: MeV / number of protons] and 0.2 [unit: MeV] [unit: MeV] is set as the lower limit, and other than the lower limit (Iii) The following (n, np) is within the range where the upper limit is the energy value at which the reaction cross section of the (n, p) reaction at the energy value is equal to the reaction cross section of the (n, p) reaction at the lower limit. In the case of the reaction, the number obtained by multiplying the threshold of (n, np) reaction by the atomic number (Z) of the gas source target by 0.10 [unit: MeV / number of protons] and 0.2 [unit] : MeV] [unit: MeV] is the lower limit, and the reaction cross section of the (n, np) reaction at an energy value other than the lower limit is equal to the reaction cross section of the (n, np) reaction at the lower limit (Iv) The following (n, n ′) reaction In the case of (n, n ′), the value obtained by adding 0.15 MeV to the (n, n ′) reaction threshold [unit: MeV] is the lower limit, and the reaction cross section of the (n, n ′) reaction at an energy value other than the lower limit. and small accelerator size enough to Ru to generate fast neutrons with the energy value in a range but that the energy value equal to (n, n ') cross sections of the reaction in the lower limit and the upper limit value, the gas raw material target comprising a target support means for supporting a sample container enclosing the said fast neutrons caused by the charged particle beam irradiation irradiated to the gas material targets enclosed in the sample container, either below according to the type of gas material target An apparatus for producing a radioisotope, which causes such a reaction to generate a radioisotope.
(1) (n, 2n) reaction: reaction that releases two neutrons by irradiation of one neutron (2) (n, p) reaction: reaction that releases one proton by irradiation of one neutron (3) (n, np) reaction: reaction that releases one neutron and one proton by irradiation of one neutron (4) (n, n ') reaction: incident neutron by irradiation of one neutron Reaction that emits one neutron of energy different from the energy of

[8] In the seventh invention, the gas source target includes one or a plurality of target nuclei in Table 1 below , and causes (n, 2n) reaction to generate a radioisotope. Equipment for producing radioisotopes.

[9] In the seventh invention, the gas source target includes one or a plurality of target nuclei in Table 2 below , and a (n, p) reaction is caused to generate a radioisotope. Equipment for producing radioisotopes.

[10] In the seventh invention, the gas source target includes one or a plurality of target nuclei in Table 3 below , and a (n, np) reaction is caused to generate a radioisotope. Equipment for producing radioisotopes.

[11] The radioisotope manufacturing apparatus according to the seventh aspect, wherein the gas source target is ¹²⁹ Xe, and a (n, n ′) reaction is caused to generate a radioisotope.

[12] In any of the above aspects to seventh to 11, fast gas material target and the sample container enclosing by fast neutron generator in a state of being adhered to or spaced provided to the accelerator exit section states An apparatus for producing a radioisotope characterized by irradiating a gas source target with neutrons.

[13] In any one of the seventh to twelfth inventions, the fast neutron generator provided in the accelerator emitting portion includes a cooling means, and the fast neutron generator has a partition function between the vacuum chamber and the atmosphere side. and apparatus for producing a radioisotope, wherein the raw material target is set in a state of or spaced state of being in close contact with the fast neutron generator.

According to the present invention, a source target is irradiated with fast neutrons generated by charged particle beam irradiation from a small accelerator, and (n, 2n) reaction, (n, p) reaction, (n, np) reaction, (n , N ′) Since any one of the reactions was caused to produce RI, enrichment ²³⁵ U was not used, reactor facilities were not used, and high-strength, long-lived radioactive waste was produced. This makes it possible to stably supply RI efficiently and inexpensively.

  In addition, the RI manufacturing apparatus according to the present invention does not need to be regulated by nuclear fuel materials and can be miniaturized. Therefore, there is an advantage that it can be easily used in facilities such as hospitals.

  Furthermore, according to the present invention, since the RI is generated by irradiating the raw material target with neutrons, the neutron has no charge compared to the case where the target is irradiated with a positively charged proton beam. In this case, a small-scale accelerator can be used in the same manner as in the case of a light target nuclide. Further, since the target can be arranged in the atmosphere, there is an advantage that the degree of freedom in the arrangement of the target is increased. This is considered to give immense convenience to various users.

It is a figure which shows the production amount distribution of the nuclide produced | generated by ²³⁵ U nuclear fission in a nuclear reactor. It is a graph which shows the reaction cross-section evaluation value of a raw material target and a fast neutron. It is a figure showing typically RI manufacture device by one embodiment of the present invention. It is a figure which shows the sample container used in one Embodiment of this invention. It is a figure which shows typically the principal part of RI manufacturing apparatus by another embodiment of this invention. It is a block diagram which shows the manufacturing procedure of RI by this invention. Basal fast neutrons caused by the charged particle beam irradiation from the small accelerator, by irradiating the raw material target containing target nucleus ^{133 Cs,} indicating that ^{the 133} Xe is generated ^from the excited state of 233keV of ¹³³ Xe It is a figure which shows the measurement data of the 233 keV gamma ray emitted by collapsing into a state as evidence. It is a figure which shows the evaluation value of the neutron energy dependence of the cross-sectional area of (n, p) reaction which occurs when a ¹³³ Cs target nucleus is irradiated with neutron. It is a figure which shows the evaluation value of the neutron energy dependence of the cross-sectional area of (n, 2n) reaction which occurs when a ¹³⁴ Xe target nucleus is irradiated with neutron.

  Hereinafter, the present invention will be described in detail based on embodiments.

In the present invention, a radioisotope used for radioactive diagnostic agents, etc., a high-speed neutrons are generated by the charged particle beam irradiation from the small accelerator gas material targets enclosed in the sample container by irradiating, any of the following reactions Produced by raising. In the present invention, fast neutron means neutron having energy of 0.1 MeV or more.
(1) (n, 2n) reaction: reaction that releases two neutrons by irradiation of one neutron (2) (n, p) reaction: reaction that releases one proton by irradiation of one neutron (3) (n, np) reaction: reaction that releases one neutron and one proton by irradiation of one neutron (4) (n, n ') reaction: incident neutron by irradiation of one neutron Reaction that emits one neutron of energy different from the energy of

When a raw material target is irradiated with fast neutrons, (n, 2n) reaction, (n, p) reaction, (n, 3n) reaction, (n, ⁴ He) reaction, (n, np) reaction, (n, n ′) ) Various reactions such as reactions occur, but the raw material target of the present invention has a very large reaction cross section in the above reaction depending on the type of the target, even compared to the production of radioactive isotopes using nuclear reactors. It was confirmed that the radioisotope can be obtained efficiently without inferiority. According to the present invention, a desired radioisotope can be produced without generating a large amount of radioactive waste as in the case of using a nuclear reactor, while reducing the radioactivity and without impairing the stable supply. be able to.

FIG. 2 is a graph showing, as an example, evaluation values of neutron energy and reaction cross-section when a raw material target having ⁸⁶ Kr as a target nucleus is irradiated with fast neutrons. From FIG. 2, it can be seen that when the raw material target is irradiated with fast neutrons, the (n, 2n) reaction has an advantage depending on the value of neutron energy and has a much larger reaction cross section than other reactions.

In the present invention, radioisotopes (product nuclei) are produced using the target nuclei shown in Tables 1 to 4 using various reactions.

Among the above, the production nuclei ¹²³ I and ¹²⁵ I are obtained by β decay and can be made carrier-free.

  Each of the above-mentioned production nuclei can be made carrier-free because one neutron of the target is replaced with one proton.

  The above-mentioned production nucleus can be made carrier-free because one proton is reduced from the target.

In the present invention, in order to produce a radioactive isotope, without using a reactor, irradiated with fast neutrons caused by the charged particle beam irradiation using a small accelerator raw material target. In this way, compared with the case of using a nuclear reactor, a large amount of radioactive waste is not generated, and unnecessary radioactivity can be reduced.

As a small accelerator for accelerating a charged particle beam for generating fast neutrons, for example, a commercially available small accelerator may be used, or the Japan Atomic Energy Agency (NES) Fusion Neutron Engineering Neutron Source Facility (FNS), which is the facility of the present applicant. You may use facilities, such as DT neutron source.

The fast neutron energy used in the present invention is in the following range.
(N, 2n) reaction: a value obtained by adding 0.5 MeV to the threshold value of (n, 2n) reaction [unit: MeV] as a lower limit, and a reaction cross-sectional area of (n, 2n) reaction at an energy value other than the lower limit Is a range in which the upper limit value is an energy value equal to the reaction cross-sectional area of the (n, 2n) reaction at the lower limit value. (N, p) reaction: The atomic number (Z) of the gas source target is set to the threshold value of the (n, p) reaction. ) Multiplied by 0.10 [unit: MeV / number of protons] and 0.2 [unit: MeV] plus [unit: MeV] as the lower limit, and energy values other than the lower limit (N, p) Reaction cross-sectional area in which the upper limit is the energy value at which the reaction cross-sectional area of the (n, p) reaction is equal to the lower limit value (n, np) reaction: (n, np) reaction threshold in, the gas raw material target atomic number (Z) 0.10 (N, np) reaction at an energy value other than the lower limit value, with a value obtained by multiplying the unit: MeV / number of protons and a value obtained by adding 0.2 [unit: MeV] [unit: MeV] as the lower limit value The upper limit of the energy value at which the reaction cross-sectional area of is equal to the reaction cross-sectional area of the (n, np) reaction at the lower limit value (n, n ′) reaction: 0.15 MeV as the threshold value for the (n, n ′) reaction [Unit: MeV] is set as the lower limit, and the reaction cross section of the (n, n ′) reaction at an energy value other than the lower limit is equal to the reaction cross section of the (n, n ′) reaction at the lower limit. Range with energy value as upper limit

  Here, the threshold value of the nuclear reaction is the energy value when the reaction cross section starts to take a value other than 0 (burn) from the state of 0 (burn) in the graph as shown in FIG. 2 showing the neutron energy and the reaction cross section. That is.

When the reaction threshold exceeds 14 MeV, the fast neutrons irradiate a beam of proton (p) or deuterium ( ² H) to a metal Li (lithium), metal Be (beryllium), or C (carbon), which will be described later. It is preferable to generate them. Alternatively, fast neutrons obtained together with helium ( ⁴ He) can be used by irradiating deuterium ( ² H) beam to deuterium ( ³ H) including the case where the reaction threshold is around 14.5 MeV. In this case, a facility such as a DT neutron source such as the Japan Atomic Energy Agency Fusion Neutron Engineering Neutron Source Facility (FNS), which is the applicant's equipment, may be used.

When the reaction threshold is relatively small, such as 1 to 5.6 MeV, the lithium ( ⁷ Li) is irradiated with protons (p),
⁷ Li + p → ⁷ Be + n
Or deuterium is irradiated with deuterium,
² H + ² H → ³ He + n
By this reaction, neutrons having a desired size can be generated. Any of them may be used according to the threshold value of the target material target.

In addition, when irradiated with protons to generate neutrons metal Li (lithium), the reaction neutron energy generated by ^{{p + 7 Li → n +} 7 Be} (En) is given by the following equation.
En = {R × cos θ + (1−R ² × sin ² θ) ^1/2 } ² × {M _Be × (E _cm + Q) / (M _Be + M _n )}
R = [M _n × M _p × E _cm / {M _Be × M _Li × (E _cm + Q)}] ^1/2
E _cm = M _Li × E _p / (M _Li + M _p ) where E _p is the proton energy, and M _p , M _n , M _Li , and M _Be are the static masses of proton, neutron, Li, and Be is there. Further, θ is an angle formed between the neutron generated by this reaction and the proton beam axis. Q is the threshold of this reaction, which is -1.644 MeV.
From this equation, it can be seen that, for example, when a low energy proton of 16 MeV is used, fast neutrons of about 14 MeV can be obtained in the proton beam axis direction. Since neutrons are mainly emitted in the proton beam direction, it is important to set the target in the beam axis direction.

  From this equation, it can be seen that fast neutrons of about 14 MeV can be obtained in the direction of θ = 0 when, for example, high-energy protons of 16 MeV are used. In this case, since neutrons are mainly emitted in the proton beam direction, it is important to set the target in the beam axis direction.

Further, for example, deuterium ( ² H) beam can be irradiated to deuterium ( ³ H), and fast neutrons can be generated together with helium ( ⁴ He) in the next reaction.
² H + ³ H ⁴ He + n

The neutron energy (En) generated by this reaction is given by the following relational expression.
4 × En = Ed + 2 × {2 × Ed × En} ^1/2 × cos θ + 3 × Q
Here, Ed is deuterium energy, Q is the generated energy of the reaction, and Q = 17.6 MeV. θ is the angle between the generated neutrons and incident deuterium. From this equation, it can be seen that 14 MeV fast neutrons can be obtained by using, for example, 0.35 MeV low energy deuterium. At the International Fusion Materials Irradiation Facility (IFFIF), which is currently underway, liquid lithium (Li) is irradiated with deuterium to produce high-intensity fast neutrons. Furthermore, fast neutrons can be generated even when metal Li or metal beryllium (Be) is irradiated with protons or deuterium.

Here, the production efficiency of RI by fast neutrons will be examined by taking ⁹⁹ Mo production by a ¹⁰⁰ Mo (n, 2n) reaction as an example. The amount of ⁹⁹ Mo produced by fission in the nuclear reactor (Y _furnace ) is given below.

²³⁵ U: Concentration 20%. The fission cross section due to the reaction between thermal neutrons and ²³⁵ U is 585 burns. Among them, the production ratio of ⁹⁹ Mo is 6% (see FIG. 1). From the above, the amount of ⁹⁹ Mo generated in this U = 0.20 × 585 × 0.06 = 7 burns.

¹⁰⁰ Mo: natural abundance ratio 9.6%. ⁹⁹ Mo production reaction cross section by fast neutron is 1.5 burn. From the above, the amount of ⁹⁹ Mo produced from natural Mo (Y _{high speed} ) = 0.096 × 1.5 = 0.14 burn.

That is, the ratio of Y _{high speed} to Y _furnace = Y _{high speed} / Y _furnace = 0.14 / 7 = 0.02 Formula (1)
The amount of ⁹⁹ Mo produced by fast neutrons is 2% in the case of a nuclear reactor, excluding the amount of neutrons.

By the way, as for the amount of neutrons, the thermal neutron quantity of the _reactor φ _Reactor : In the case of Japan Nuclear Research and Development Agency research reactor facility JRR3, φ _Reactor = 10 ¹⁴ pieces / (cm ² · second)
Formula (2)
Amount of fast neutrons φ _Fast : In the case of IFMIF, φ _fast = 10 ¹⁴ pieces / (cm ² · sec)
Formula (3)
That is, the ratio of the fast neutron amount to the reactor amount is: φ _fast / φ _reactor = 1 formula (4)
It becomes. Above, in view of the neutron amount, the ratio of the fast neutron ^{99 Mo} production amount by utilizing a reactor ^{99 Mo} production amount by the use it is given below.
0.02 × 1 = 0.02 Formula (5)
Here, considering that a high concentration of ¹⁰⁰ Mo can be obtained relatively easily (for example, assuming 100% concentration), the ratio of equation (5) is calculated from equations (1) and (4):
0.02 ÷ 9.6 × 100 = 0.21 Formula (6)
It becomes. In other words, according to the present invention, it can be seen that even using fast neutrons, ⁹⁹ Mo can be produced in an amount sufficiently comparable to the amount produced in the nuclear reactor. The above also applies to each target that is the subject of the present invention.

FIG. 3 schematically shows an RI manufacturing apparatus according to an embodiment of the present invention.
In the figure, 1 is a high voltage power source, 2 is a power cable, 3 is an accelerator terminal, 4 is an accelerator tube, 5 is a deuteron transport line, 6 is a fast neutron generator, 7 is a cooling tube, 8 cooling system, 9 is a raw material A target, 10 is a sample container, 11 is a target support, and 12 is an RI container (target storage) with radiation shielding. FIGS. 3A and 3B respectively show a state in which the raw material target 9 is in close contact with the fast neutron generator 6 and a state in which the source target 9 is separated.

The generation efficiency of RI increases when the raw material target 9 is brought into close contact with the fast neutron generator 6 as shown in FIG. In this case, the raw material target 9 or the sample container 10 containing it is brought into close contact with the tips of the fast neutron generator 6 and the cooling tube 7 via a cooling member made of, for example, Cu. In this case, the cooling member provided in the fast neutron generator 6 has a partition function between the vacuum chamber of the deuteron transport line 5 and the atmosphere side where the raw material target 9 is located. In some cases, as shown in FIG. 3B, the raw material target 9 may be separated from the fast neutron generator 6 by about 10 mm, and this distance is not limited.

  The high voltage power supply 1 outputs a high voltage for making the deuterium beam energy of about 0.35 MeV in order to generate a large amount of neutrons by the neutron generation reaction. The power cable 2 is for applying the high voltage of the high voltage power supply 1 to the acceleration tube 4 in contact with the accelerator terminal 3. In the fast neutron generator 6, a metal plate having excellent thermal conductivity such as Cu is provided with a deposition film such as titanium occluded with deuterium, for example. It plays the role of generating a large amount of neutrons by causing the neutron generation reaction. The cooling system 8 serves to cool the metal plate by the cooling pipe 7 in order to prevent thermal diffusion of the deuterium in the metal plate irradiated with the deuterium beam. Cooling is performed by water cooling or the like. The metal plate may be a fixed type or a rotary type.

  As the raw material target 9, it is possible to use a natural gas target element or a material concentrated to a natural abundance ratio of the gas target element. In that case, the process for concentration is performed.

Neutrons are emitted from the accelerator terminal 3 in all directions, and the neutron flux (pieces / cm ² · sec) decreases at 1 / r ² . For this reason, when the raw material target 9 is brought into close contact with the fast neutron generator 6 of the accelerator terminal 3, the RI generation efficiency is maximized. In some cases, the raw material target 9 may be separated from the fast neutron generator 6 of the accelerator terminal 3, and in that case, it is usually separated by a distance of about 10 mm, but this is not restrictive.

  The RI container 12 includes a radiation shield, and the generated RI is put in this, taken out of the laboratory, and transported and moved to a required place. Each member other than the RI container 12 also shields radiation as necessary.

The target is irradiated with fast neutrons by the apparatus configured as described above, and the irradiation time can be set in consideration of the half-life of the nuclide to be generated. If the half-life is longer than 5 days, the desired amount of RI can be obtained if the irradiation time is about 5 days. In this case, since the use of fast neutrons is generated by the charged particle beam irradiation from the small accelerator, not a large amount of radioactive waste was generated since it does not utilize nuclear fission, also relatively large above the reaction of the reactive cross-sectional area Therefore, a desired RI can be stably supplied with high efficiency. Furthermore, since the apparatus configuration can be very downsized using a commercially available accelerator, RI can be manufactured and used easily and stably in a facility such as a hospital.

In addition, when the reaction threshold of the target target is 15 MeV or more, an apparatus having the following configuration is used. In order to generate a large amount of neutrons by the neutron generation reaction, the high voltage power supply 1 outputs a high voltage for making the proton beam energy of about 25 MeV, for example. The power cable 2 is for applying the high voltage of the high voltage power supply 1 to the acceleration tube 4 in contact with the accelerator terminal 3. The fast neutron generator 6 is set with a metallic Li thin film provided on a metal plate excellent in thermal conductivity such as Cu, and the fast neutron generator 6 causes the above neutron generation reaction, It plays a role in generating neutrons. The cooling system 8 serves to cool the metal plate by the cooling pipe 7 in order to prevent Li on the surface of the Cu metal plate irradiated with the proton beam from being thermally diffused. Cooling is performed by water cooling or the like. The metal plate may be a fixed type or a rotary type. In this case, most of the neutrons are emitted from the fast neutron generator 6 along the proton beam axis, and the neutron flux (pieces / cm ² · sec) decreases at 1 / r ² . Therefore, it is preferable that the raw material target 9 is disposed in close contact with the fast neutron generating unit 6 or in proximity (separated to about 10 mm). Here, r is the distance from the neutron source.

  FIG. 4 shows an example of the sample container 10. As the sample container 10, for example, a highly airtight container made of stainless steel is used. As shown in FIGS. 4A and 4B, the sample container 10 is provided with a vacuum valve 10A so that the gas source target 9 can be filled and the generated RI can be taken out. For example, when krypton gas is used as the gas source target 9 and bromine ions are generated as RI, an alkali solution such as sodium hydroxide or an acid such as hydrochloric acid is injected into the sample container 10 and then stirred, and bromine generated by the nuclear reaction. Ions are dissolved. The krypton gas is exhausted and collected by connecting the vacuum valve 10A to the air collection system 13 as shown in FIG. After adsorbing this to an adsorbent such as molecular sieve, the vacuum line is closed. At this time, the adsorbent is cooled with liquid nitrogen as necessary.

Next, another embodiment of the present invention will be described.
FIG. 5 is a diagram schematically showing a main part of an RI manufacturing apparatus according to another embodiment of the present invention. FIG. 5A is a schematic diagram seen from a direction perpendicular to the deuterium beam traveling direction, and a fast neutron generator. (B) is a schematic view seen from the traveling direction of the deuterium beam. (B) is a case where the fast neutron generator is separated from the raw material target.

  In the figure, 21 is a deuterium beam, 22 is a rectangular parallelepiped vacuum beam tube, 23 is a copper plate having a titanium film adsorbing tritium (tritium), 24 is a raw material target, 25 is a cooling member, and 26 is a proton beam. . The cooling member 25 may be integrated with the copper plate 23. In this case, the copper plate 23 has an inner wall and an outer wall, and a titanium film adsorbing deuterium on the surface of the copper plate 23 on the inner wall (vacuum chamber side). The raw material target 24 is disposed in close contact with or spaced from the surface of the copper plate on the outer wall (atmosphere side) so that a cooling medium such as water passes through the space between the inner wall and the outer wall. Yes.

The fast neutrons generated by irradiating the deuterium ( ² H ⁺ ) beam 21 to the deuterium ( ³ H) isotropically in almost the entire space regardless of the incident direction of the deuterium beam 21. Has the property of being released. For this reason, in order to make maximum use of neutrons generated in a limited neutron utilization time, the raw material target 24 is arranged as follows.

  In order to prevent the high-intensity deuterium beam 21 irradiated to the copper plate 23 provided with the tritium-containing titanium film from raising the temperature of titanium and causing thermal diffusion of the deuterium, the tritium-containing titanium film was provided. The copper plate 23 is cooled by the cooling pipe 25. In order to use a higher-intensity deuterium beam 21 within a given cooling capacity range, it is conceivable to reduce the heat load per unit area provided by the deuterium beam 21. Therefore, the size of the deuterium beam 21 is changed from the usual 5 mm diameter to, for example, 10 mm diameter by changing the beam transport system of the accelerator. As a result, the heat load per unit area can be reduced to ¼, so that the intensity is four times that of a conventional deuterium beam, and the resulting neutrons can be used four times as much. Further, since fast neutrons are isotropically emitted into the entire space, the raw material target 24 is set not only in front of the deuterium beam 21 but also on the side surface as shown in FIG.

The deuterium beam 21 is irradiated to a copper plate 23 having a tritium-containing titanium film through a beam transport system in which a vacuum is maintained by a vacuum beam tube 22 which is a rectangular parallelepiped. Then ^{2 H + + 3 H → 4} He + n fast neutrons generated by the reaction, placed (closest distance) on the atmosphere side of the cooling member 25 (the copper plate 23) is irradiated to the raw material target 24. On the other hand, in order to efficiently use fast neutrons emitted backward with respect to the deuterium beam 21 incident at a right angle to the copper plate 23 having a tritium-containing titanium film, a vacuum beam tube (a rectangular parallelepiped) close to the fast neutron generation site. ) Four surfaces of 22 are processed and the raw material target 24 is embedded as shown. With such a configuration, fast neutrons are isotropically emitted into the entire space, so that RI generation is performed with higher efficiency.

  Moreover, when using a faster neutron, as mentioned above, a proton etc. are irradiated to Li or Be. In this case, most of the neutron flux is emitted along the direction of the proton beam. Therefore, the arrangement of the raw material target 24 is in front of the fast neutron generator as shown in FIGS. 5D and 5E. FIG. 5D shows the case where the raw material target 24 is brought into close contact with the fast neutron generator, and FIG. 5E shows the case where the raw material target 24 is spaced from the fast neutron generator. As described above, according to the present invention, since the raw material target 24 can be arranged not on the vacuum but on the atmosphere side, there is an advantage that the shape of the raw material target 24 and the degree of freedom in arrangement are increased.

Furthermore, when the reaction threshold of the raw material target 24 is smaller, as described above, the lithium ⁷ Li is irradiated with protons (p),
⁷ Li + p → ⁷ Be + n
Or deuterium is irradiated with deuterium,
² H + ² H → ³ He + n
The neutrons having a desired size are generated and used by the above reaction.

  Next, a method for manufacturing RI according to the present invention will be described.

Manufacturing method of the RI according to the present invention basically as described above, the gas material target is irradiated with fast neutrons caused by the charged particle beam irradiation from the small accelerator, by cause said reaction, RI Manufacturing.

  Hereinafter, an example of an RI manufacturing method according to the present invention will be described with reference to the block diagram of the manufacturing procedure of FIG.

  First, for example, a natural gas target is hermetically sealed in a sample container. (Step S1).

  Next, the gas source target sealed in the sample container is set at the neutron irradiation position (step S2).

Next, a deuterium ( ² H) beam of 0.35 MeV, for example, is irradiated from a neutron generator onto a copper plate having a deuterium ( ³ H) -containing titanium film. As a result, fast neutrons of about 14 MeV are generated (step S3) .

  In the raw material target, this fast neutron irradiation causes the above-described reactions to occur predominantly according to the type of material, and RI is generated (step S4).

  After performing neutron irradiation for an appropriate time, the irradiation is stopped, the sample container containing the RI is taken out, and the desired RI is obtained (step S5).

  Although an example of the manufacturing method has been described above, of course, a desired amount of RI can be obtained for a raw material target having a larger reaction threshold and a raw material target having a smaller reaction threshold by the same method.

The present inventors conducted the following experiment in order to confirm that RI can be generated by irradiating a raw material target with a neutron beam generated by irradiation of a charged particle beam from a small accelerator.

<Experimental purpose>
* Confirmation that ⁹⁹ Mo is generated with 14 MeV fast neutrons using a natural Mo sample with the expected reaction cross section * Generated with 14 MeV neutrons using the ⁹³ Nb sample used to determine the absolute value of the above reaction cross section Measurement of ⁹² Nb radiation and confirmation that it can be used to determine the cross-sectional area * ⁹⁹ Quantitative evaluation of residual radioisotope produced in association with Mo production reaction * ² H + ³ H → ⁴ He + n reaction Verifying 14MeV neutron is stable generated by the neutron intensity to be expected ^{(3 H} target performance evaluation)
* Confirmation that ² H (deuterium beam) for inducing the above reaction is supplied stably (Verification that small accelerator operates stably)
* Confirmation that Mo and Nb targets can be easily and flexibly installed and removed from the neutron irradiation site <Experiment location> Neutron Source Facility for Fusion Neutron Engineering, Japan Atomic Energy Agency (FNS)
<Experiment date>
Neutron irradiation experiment: January 27 to January 30, 2009 (6 hours of irradiation per day)
Measurement of generated Mo radioactivity: January 27 to February 5, 2009 <Sample> Natural Mo
Sample 1: Diameter: about 10 mm, thickness: 50 microns (0.05 mm), weight 40.214 mg
Sample 2: Diameter: about 10 mm, thickness: 5 microns (0.005 mm), weight 3.663 mg
Sample 1 was measured after 6 hours of irradiation.
Sample 2 was measured after neutron irradiation until the last day.
<Sample> ⁹³ Nb
Sample 3: diameter 10 mm, thickness: 0.1 mm, weight 69.4 mg
<Mo target installation location>
² Location 10 cm away from the neutron generation site in the direction of extension of the H beam axis.
<Neutral irradiation conditions>
* 14 MeV neutron production reaction
² H + ³ H → ⁴ He + n: ² H beam energy: 0.35 MeV
* Neutron generation amount 1.8 × 10 ¹¹ n / cm ² · sec [January 27] to 1.5 × 10 ¹¹ n / cm ² · sec [January 30]
^<99 Mo production reaction>
¹⁰⁰ Mo + n → ⁹⁹ Mo + 2n
< ⁹² Nb production reaction>
⁹³ Nb + n → ⁹² Nb + 2n
<Measurement of ⁹⁹ Mo and residual radioactivity (measured with FNS)>
* Measurement condition: Start cooling after approximately 1 hour after neutron irradiation * Measurer: Ge semiconductor detector * ⁹⁹ Mo sample and ⁹² Nb sample placement: Set 5cm away from Ge detector

<Result>
* Confirm that ⁹⁹ Mo is produced in the amount originally predicted * Confirm that ⁹³ Nb sample can be used to determine ⁹⁹ Mo cross-sectional area * Quantitative determination of residual radioisotope generated accompanying ⁹⁹ Mo formation reaction Evaluation. (Check that it is a small amount compared to the amount of ⁹⁹ Mo).
* Confirmed that 14 MeV neutrons generated by ² H + ³ H → ⁴ He + n reaction are stably generated with the expected neutron intensity ( ³ H target could be evaluated to have high performance)
* It was confirmed that ² H (deuterium beam) for inducing the above reaction was stably supplied.
(Verification of stable operation of small accelerators)
* It was confirmed that the Mo target and Nb target can be easily and flexibly installed and removed from the neutron irradiation site.

Next, the present inventors irradiate a raw material target with a neutron beam generated by charged particle beam irradiation from a small accelerator, and emit one proton by irradiation with one neutron (n, p). The following experiment was performed to confirm that the reaction was caused and RI could be generated. This experiment proves that RI ¹³³ Xe can be generated by the ¹³⁴ Xe (n, 2n) ¹³³ Xe reaction when the gas source target ¹³⁴ Xe is used.

<Experiment location> Japan Atomic Energy Agency, Neutron Source Facility for Fusion Neutron Engineering (FNS)
<Sample> Cesium carbonate 4g
<Raw material target installation location>
² Location 10 cm away from the neutron generation site in the direction of extension of the H beam axis.
<Neutral irradiation conditions>
* 14 MeV neutron production reaction
² H + ³ H → ⁴ He + n: ² H beam energy: 0.35 MeV
* In the neutron generation amount occurrence point ^{1.8 × 10 11 n / cm 2} · sec ^<133 Xe and measurement of residual radioactivity (measured in FNS)>
* Measurement conditions: 1 hour after neutron irradiation is completed * Measurement: Ge semiconductor detector * ¹³³ Xe sample placement: set at a position 5 cm away from Ge detector * From ¹³³ Xe 233 keV excited state to ground state The 233 keV gamma ray emitted when it decays is confirmed by measurement with a Ge semiconductor detector. The measurement result is shown in FIG. FIG. 8 shows the evaluation value of the neutron energy dependence of the (n, p) reaction cross section that occurs when the ¹³³ Cs target is irradiated with neutrons (JENDL-3.3 (general purpose of Japan Atomic Energy Agency). From the evaluated nuclear data library)). It is about 0.01 burn at 14 MeV. Furthermore, FIG. 9 shows the evaluation value of the neutron energy dependence of the (n, 2n) reaction cross section that occurs when a ¹³⁴ Xe target is irradiated with neutrons (from JENDL-3.3). It is about 1.5 burns at 14 MeV.

From the above measurement, data of ¹³³ Cs (n, p) ¹³³ Xe reaction cross section, which is about 0.01 burn with high-speed 14 MeV neutrons, could be obtained. ^{In 134} Xe, the ¹³⁴ Xe (n, 2n) ¹³³ Xe reaction cross-sectional area is about 1.5 burns, indicating that ¹³⁴ Xe (n, 2n) ¹³³ Xe reaction occurs.

DESCRIPTION OF SYMBOLS 1 High voltage power supply 2 Power supply cable 3 Accelerator terminal 4 Acceleration tube 5 Deuteron transport line 6 Fast neutron generating part 7 Cooling tube 8 Cooling system 9 Raw material target 10 Target support frame 11 Target support stand or sample container 12 RI container (target storage) Warehouse)
21 Deuterium beam 22 Vacuum transport line 23 Copper plate with a deuterium-containing titanium film 24 Raw material target 25 Cooling tube 26 Proton beam

Claims (13)

Power source for applying a voltage to accelerate the charged particle beam consisting of deuterium or protons, the voltage from the power supply is applied, an acceleration tube for accelerating the charged particle beam, and, provided on the accelerator exit section Rutotomoni, the tritium is disposed a fast neutron generator target occluded titanium, with fast neutron generator which the charged particle beam is accelerated to generate a fast neutron irradiated, (i) below (n, 2n ) In the case of a reaction, the value obtained by adding 0.5 MeV to the (n, 2n) reaction threshold [unit: MeV] is the lower limit, and the reaction cross section of the (n, 2n) reaction at an energy value other than the lower limit is Within the range where the upper limit is the energy value equal to the reaction cross-sectional area of the (n, 2n) reaction at the lower limit, (ii) in the case of the following (n, p) reaction, Gas source target The value obtained by multiplying the child number (Z) by 0.10 [unit: MeV / number of protons] and 0.2 [unit: MeV] [unit: MeV] is the lower limit, and other than the lower limit (Iii) The following (n, np) is within the range where the upper limit is the energy value at which the reaction cross section of the (n, p) reaction at the energy value is equal to the reaction cross section of the (n, p) reaction at the lower limit. In the case of the reaction, the number obtained by multiplying the threshold of (n, np) reaction by the atomic number (Z) of the gas source target by 0.10 [unit: MeV / number of protons] and 0.2 [unit] : MeV] [unit: MeV] is the lower limit, and the reaction cross section of the (n, np) reaction at an energy value other than the lower limit is equal to the reaction cross section of the (n, np) reaction at the lower limit (Iv) the following (n, n ′) reaction In this case, the value (unit: MeV) obtained by adding 0.15 MeV to the threshold value of (n, n ′) reaction is set as the lower limit value, and the reaction cross-sectional area of (n, n ′) reaction at an energy value other than the lower limit value is (n, n ') in the lower limit value using a scale small accelerator enough to fast neutrons Ru is generated having an energy value within a range that the reaction upper limit energy value equal to the cross-sectional area of the reaction,
The fast neutrons are generated by the charged particle beam irradiation, irradiated to the gas material target encapsulating sample container, depending on the type of gas raw material target to cause one of the following reactions to produce radioactive isotopes A method for producing a radioisotope characterized by the above.
(1) (n, 2n) reaction: reaction that releases two neutrons by irradiation of one neutron (2) (n, p) reaction: reaction that releases one proton by irradiation of one neutron (3) (n, np) reaction: reaction that releases one neutron and one proton by irradiation of one neutron (4) (n, n ') reaction: incident neutron by irradiation of one neutron Reaction that emits one neutron of energy different from the energy of The radioisotope according to claim 1, wherein the gas source target includes one or a plurality of target nuclei in Table 1 below and causes (n, 2n) reaction to generate a radioisotope. Manufacturing method.

The radioisotope according to claim 1, wherein the gaseous source target includes one or a plurality of target nuclei in Table 2 below and causes a (n, p) reaction to generate a radioisotope. Manufacturing method.

The radioisotope according to claim 1, wherein the gas source target includes one or a plurality of target nuclei in Table 3 below to cause a (n, np) reaction to generate a radioisotope. Manufacturing method.

The method for producing a radioisotope according to claim 1, wherein the gas source target is ¹²⁹ Xe and a (n, n ′) reaction is caused to generate a radioisotope.   The gas source target is irradiated with fast neutrons in a state in which the sample container enclosing the gas source target is in close contact with or separated from the fast neutron generator provided in the accelerator emission unit. The method for producing a radioisotope according to any one of 5 to 5. Power source for applying a voltage to accelerate the charged particle beam consisting of deuterium or protons, the voltage from the power supply is applied, an acceleration tube for accelerating the charged particle beam, and, Rutotomoni provided to the accelerator exit section, 3 deuterium is arranged fast neutron generator target of occluded titanium, with fast neutron generator which the charged particle beam accelerated in this occurs the fast neutron irradiated, (i) below (n, 2n) In the case of a reaction, a value obtained by adding 0.5 MeV to the (n, 2n) reaction threshold [unit: MeV] is the lower limit, and the reaction cross-sectional area of the (n, 2n) reaction at an energy value other than the lower limit is the lower limit. Within the range where the energy value equal to the reaction cross-sectional area of the (n, 2n) reaction in the value is the upper limit, (ii) In the case of the following (n, p) reaction, the (n, p) reaction threshold value is gas Atomic number of raw material target A value obtained by multiplying the number (Z) by 0.10 [unit: MeV / number of protons] and 0.2 [unit: MeV] [unit: MeV] is set as the lower limit, and other than the lower limit (Iii) The following (n, np) reaction within the range where the upper limit is the energy value at which the reaction cross section of the (n, p) reaction at the energy value is equal to the reaction cross sectional area of the (n, p) reaction at the lower limit In the case of (n, np) reaction, the number obtained by multiplying the atomic number (Z) of the gas source target by 0.10 [unit: MeV / number of protons] and 0.2 [unit: The value obtained by adding [MeV] [unit: MeV] is the lower limit, and the reaction cross section of the (n, np) reaction at an energy value other than the lower limit is equal to the reaction cross section of the (n, np) reaction at the lower limit. Within the range where the energy value is the upper limit, (iv) In the following (n, n ') reaction The value (unit: MeV) obtained by adding 0.15 MeV to the (n, n ′) reaction threshold is the lower limit, and the reaction cross-sectional area of the (n, n ′) reaction at an energy value other than the lower limit is the lower limit. and (n, n ') order of magnitude smaller accelerator of Ru to generate fast neutrons with cross sections with equal energy value has the energy value within the range of the upper limit of the reaction in the value,
Provided with a target support means for supporting a sample container enclosing a gas source target,
The fast neutrons are generated by the charged particle beam irradiation irradiated to the gas material targets enclosed in the sample container, in accordance with the type of gas raw material target to cause one of the following reactions, thereby generating the radioisotopes An apparatus for producing radioisotopes characterized by
(1) (n, 2n) reaction: reaction that releases two neutrons by irradiation of one neutron (2) (n, p) reaction: reaction that releases one proton by irradiation of one neutron (3) (n, np) reaction: reaction that releases one neutron and one proton by irradiation of one neutron (4) (n, n ') reaction: incident neutron by irradiation of one neutron Reaction that emits one neutron of energy different from the energy of The radioisotope according to claim 7, wherein the gaseous source target includes one or a plurality of target nuclei in Table 1 and causes a (n, 2n) reaction to generate a radioisotope. Manufacturing equipment.

The radioisotope according to claim 7, wherein the gas source target includes one or more target nuclei in Table 2 below, and causes a (n, p) reaction to generate a radioisotope. Manufacturing equipment.

The radioisotope according to claim 7, wherein the gas source target includes one or a plurality of target nuclei in Table 3 below and causes a (n, np) reaction to generate a radioisotope. Manufacturing equipment.

The apparatus for producing a radioisotope according to claim 7, wherein the gas source target is ¹²⁹ Xe and a (n, n ′) reaction is caused to generate a radioisotope.   The fast neutron is irradiated to the gaseous raw material target in a state in which the sample container enclosing the gaseous raw material target is brought into close contact with or separated from the fast neutron generating section provided in the accelerator emitting section. The apparatus for producing a radioisotope according to any one of 11 to 11. Fast neutron generator provided in the accelerator exit section comprises a cooling means, and fast neutron generator has a partition wall function of the vacuum chamber and the atmosphere side, and a state in which the raw material target to fast neutron generator is brought into close contact or The radioisotope manufacturing apparatus according to any one of claims 7 to 12, wherein the radioisotope manufacturing apparatus is set in a separated state.

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