CS255469B1 - Method of targets irradiation in cyclotron - Google Patents

Abstract

The solution concerns the field of nuclear acceleration techniques. The essence is that to where the accelerated ions reach the required energy is placed tangentially target, with another target placed in the direction of the ions reflected tangential target.

Description

The invention relates to a method of irradiating targets in a cyclotron with a beam of accelerated ions.

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Radiation of targets on cyclotrones serves the needs of social practice. It is carried out on a circulating ion beam inside the acceleration chamber or on an external, cyclotron-led and transported beam to the appropriate location. The relative position of the beam and the target, depending on its physical properties and current load, is chosen either perpendicular or tangential, fixed or variable, eg oscillating or rotating.

In practice, due to a number of specific problems, external beam irradiation is most commonly used. This method makes it easy to adjust the size and position of the beam track, change the position of the target, ensure intensive cooling, quick replacement, etc.

The limiting factors are the efficiency of the outlet, ie 50-70%, and the permissible load of the extraction system. This limits the value of the external current in the beam and increases, for example, the cost of producing radioisotopes.

On the other hand, irradiation of targets by a circulating beam allows its full utilization. In this case, the main limiting factor is the high current density of the circulating beam, causing, in particular for isochronous cyclotrons, a thermal load of the target with a flux of 10 [mu] W / cm3 and higher. At such high loads the target material is thermally disrupted. Rotational tangential targets do not satisfactorily solve the problem either.

The problems associated with the high current densities of the inner ion beam can be greatly reduced by irradiating the targets of the invention by placing a tangential target at the point where the accelerated ions reach the desired energy, with the other target positioned in the direction of the ion path. reflected by a tangential target.

An advantage of the method according to the invention is, in particular, the possibility of irradiating multiple targets at the same time, thereby making the use of the cyclotron more efficient. Furthermore, an increase in the ion beam trace on the target is achieved, thereby reducing the heat flux density on the target, thereby allowing the use of a higher ion beam current, resulting in a shorter irradiation time.

The method of the invention is carried out by placing the tangential target at a location where the accelerated ions reach the energy required to irradiate the material of interest. Another target is placed in the direction of the path of the ions reflected by this tangential target. In order to make the cyclotron more efficient, it is possible to place additional material for irradiation even on a tangential target. The tangential target must be rotated so that the angle of incidence of the circulating ions on the irradiated surface is close to zero and that the beam dispersed by the tangential target is outside the acceleration area.

By properly selecting the geometry and spatial placement of the tangential target, tilt percentages of the total beam can be offset from the center plane of the cyclotron. In an area where the scattered beam is sufficiently distant from the acceleration area, said further target is located. The cross-section of the scattered beam at this point is many times larger than the cross-section of the circulating beam. This leads to a significant reduction in beam current density on said other target. This target can be constructed perpendicular as well as tangential.

Example

An example of the application of the invention is irradiation of a Zn target by protons accelerated in an isochronous cyclotron to 35 MeV. A 20x6 flat, rectangular, water-cooled target (Tmm with Zn-coated) was positioned approximately perpendicular to the beam immediately above the circulating beam area. A tangential target was placed 150 mm upstream of the target. setting the position of the tangential target reduced the total energy contained in the beam incident on the tangential target from 100 S to 60 L. This adjustment corresponded to the maximum beam current on said flat target. it covered almost the entire surface of the flat target.

In particular, the method of the invention can be used in the manufacture of radioisotopes.

Claims (1)

SUBJECT OF THE INVENTION A method of irradiating targets in a cyclotron with a beam of accelerated ions, characterized in that a tangential target is placed at the point where the accelerated ions reach the desired energy, and another target is positioned in the direction of the ions reflected by the tangential target.