JPH04326096A - Producing method of target body for particle accelerator and radioactive isotope - Google Patents

Abstract

PURPOSE:To recover condensed isotopes easily with high efficiency by plating a target matter on the surface of a target body for a particle accelerator which is made of silver or plated with silver, and using it as the target for the particle accelerator. CONSTITUTION:On the surface of a target body plated with silver on a copper base, <68>Zn is plated to make it a target for producing <67>Ga. It is irradiated by proton beam at about 30MeV for 20h, solved in HCl and then <67>Ga is separated and purified with a chemical separation method. The radioactivity of <65>Zn included in the remaining liquid <68>Zn recovery solution) after separating Ga is about 5m Ci/target body and is 1/4 to 1/5 of the case copper is made a target body. And due to the existence of silver plate layer, the target base copper is not solved in HCl. As the result, only Zn element is included in <68>Zn recovery solution and so chemical separation is not required for recovering <68>Zn and thus very easy and highly efficient recovery is possible.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target body for a particle accelerator such as a cyclotron, and a method for producing radioisotopes using the target body.

0002

BACKGROUND OF THE INVENTION Conventionally, copper, which has excellent thermal conductivity, has often been used as a material for such target bodies in order to increase the cooling effect in consideration of the heat generated during energy irradiation. Therefore, in the production of radioactive isotopes, from the point of view of target cooling efficiency, a copper plate is generally used as the target body, and a target material is plated on the surface to make it a stable metal, which is usually used as a solid target. There is.

0003

In order to produce radioactive isotopes with high purity and high yield, enriched isotopes are often used as target materials. However, since enriched isotopes require a great deal of labor and time to produce, they are extremely expensive. Therefore, after the target material is irradiated with charged particles and the target radioactive isotope is separated, recovery work is required to chemically separate and purify the enriched isotope.

However, when a conventional copper target body is used, the half-life is as long as 244 days due to the 65Cu(p,n)65Zn reaction caused by the copper due to the low energy nuclear reaction with protons. Moreover, since 65Zn with a high gamma ray emission energy of 1115 keV is generated,
This has been a major problem in the recovery of enriched isotopes.

In particular, when producing 67Ga, the contamination of 65Zn into 68Zn, which is an enriched isotope, is unavoidable, and chemical separation of 68Zn and 65Zn is virtually impossible, making it difficult to produce radioactive isotopes. The reality was that this was a major obstacle.

[0006] Therefore, the inventor of the present invention conducted various studies to solve the problems caused by such a copper target body, and found that if the target body is made of silver or silver plating, the target body can be cooled due to its excellent thermal conductivity. In addition to being effective, the nuclear reaction with protons does not produce long-half-life nuclides, and it is physically and chemically stable (not dissolved by acids such as HCl), so the nuclides produced by the nuclear reaction do not react with acids. The present invention has been completed based on the discovery that radioactive isotopes can be manufactured very industrially advantageously without being dissolved during treatment of the target body.

[0007]

[Means for Solving the Problems] That is, the present invention provides a target body for a particle accelerator characterized by being made of silver or silver plating, and a target material corresponding to a target radioisotope plated on the surface of the target body. This is a method for producing a radioactive isotope, which is characterized by using a particle accelerator target obtained by the above method.

In the present invention, when the target body is made of silver plating, it is preferable that the base body is made of copper, in other words, the surface of the copper base body is plated with silver to form the target body. Here, the thickness of the silver plating layer is 10 to 2
A thickness of about 0 μm is sufficient.

[0009] In the present invention, when the target body is made of silver plating, it is preferable to use a target body made entirely of silver, not only in terms of cost but also in terms of the production rate of radionuclides produced by side reactions. Comparatively better results can be obtained.

According to the present invention, by using a target obtained by plating the surface of such a silver or silver-plated target body with a target raw material corresponding to the target radioisotope, various types of of radioisotopes are produced.

In particular, if a target obtained by plating 68Zn as a target raw material on the surface of the target main body of the present invention as described above is used, 67Ga can be efficiently produced and 68Zn can be recovered at a high yield. be able to.

[0012] Similarly, by using a target obtained by plating 112Cd as a target raw material on the surface of the target body of the present invention, 111In can be efficiently produced and 112Cd can be recovered at a high yield. Can be done.

[0013]

[Examples] The present invention will be further explained below with reference to Examples and Comparative Examples.

Example 1 A target body obtained by silver plating (thickness: about 10 μm) on the surface of a copper substrate was used, and the surface was plated with 68Zn to make a target for producing 67Ga. It was irradiated with a proton beam for 20 hours. After the irradiation, the 68Zn target material was dissolved with HCl, and 67Ga was separated and purified from the solution according to a chemical separation method.

The amount of radioactivity of 65Zn contained in the residual solution after separation of 67Ga (68Zn recovery solution) is approximately 5 mCi/
It was the target itself. Incidentally, by using a silver-plated target body, theoretically in this example, 6
Although 5Zn is not included, 65Z is produced through a nuclear reaction with impurities 66Zn and 64Zn contained in the enriched isotope itself.
Although a small amount of n was produced, as is clear from the comparative example described later, the amount produced was extremely small, about 1/4 to 1/5 of the conventional amount.

Furthermore, due to the presence of the silver plating layer, the copper serving as the target base is not dissolved by HCl, and as a result, the 68Z
Since the n-recovery solution contains only Zn as an element, no chemical separation operation was required to recover 68Zn, and it was possible to recover it extremely easily and with a high yield ( Recovery rate 99.8%).

The recovered 68Zn is plated on a silver-plated target body and reused as a target for producing 67Ga.

Comparative Example 1 67Ga was separated and purified in the same manner as in Example 1 except that a copper target body (without silver plating) was used.

The amount of radioactivity of 65Zn contained in the residual solution after separation of 67Ga (68Zn recovery solution) is approximately 20 mCi.
/ It was the target itself.

[0020] Also, in the 68Zn recovery solution, 68Zn
When dissolving a target substance with HCl, HC
As a result of the chemical reaction between l and the target body copper, 6
Since copper is also dissolved at the same time as 8Zn, since it contains two elements, Cu and Zn, 68Z can be dissolved by ion exchange separation.
n was recovered (recovery rate 85-95%).

[0021]

Effects of the Invention According to the present invention, the cooling effect of the target body is excellent, and in addition, nuclides with a long half-life are not generated due to the nuclear reaction with protons, and the nuclides generated by the nuclear reaction cannot be treated with acid. Expensive concentrated isotopes can be recovered easily and in high yields because they are not dissolved during the process.
Radioactive isotopes can be produced industrially with great advantage.

Claims (4)

[Claims] 1. A target body for a particle accelerator, characterized in that it is made of silver or silver plating. 2. A method for producing a radioisotope, comprising using a target for a particle accelerator obtained by plating a target raw material corresponding to a target radioisotope on the surface of the target body according to claim 1. . 3. 68Zn as a target raw material is applied to the surface of a target body obtained by silver plating the surface of a copper base.
A method for producing 67Ga, characterized by using a particle accelerator target obtained by plating 67Ga. 4. 112C as a target raw material is applied to the surface of a target body obtained by silver plating the surface of a copper base.
A method for producing 111In, characterized by using a particle accelerator target obtained by plating 111In.