M. Castiglioni

Production of 123I for medical purposes at the Milan AVF cyclotron

Abstract A method is described for the production of large quantities of 123 I by exciting a ( p , 2 n ) reaction on enriched 124 Te targets. Results are presented for the relevant excitation functions. The irradiation technique and the chemical processes used in the separation of 123 I and the recovery of the target material are described in some detail.

The Milan Superconducting Cyclotron Project

Design work on a superconducting cyclotron started in Milan in 1975, and a detailed analysis of 1all major aspects of theproject was completed in 1976 . Meanwhile a 1:6 scale superconducting model magnet was built and successfully operated toward the end of 19772. Lack of funding prevented the continuation of the project in the following years, till about fall 1980. In recent months the Italian National Institute for Nuclear Physics (I.N.F.N.) has authorized and funded the construction of the machine, which is now underway at the University of Milan. The machine design has considerably evolved in the past year or so, both in terms of expected performances and engineering aspects. It is the purpose of this paper to rewiew the main characteristics of the accelerator and to update the status of the project.

Model Magnet for the Proposed Superconducting Cyclotron at the University of Milan

A project for a superconducting cyclotron for heavy ions has been under study for a couple of years at the Cyclotron Laboratory of the University of Milan. The machine is conceived as a booster for a 16 MV Tandem to be installed at the Laboratories of Legnaro (Padua) of the Italian National Institute for Nuclear Physics (INFN). The K design value is approximately 540, thus allowing maximum energies between approximately 55 MeV/nucleon and approximately 14 MeV/nucleon for light and heavy ions respectively. Pole diameter is 1.8 m and maximum average field should be around 41 Kgauss, to be obtained by a total of 6.5 x 10/sup 6/ Aturns in the superconducting coils. At present a three spiral sector polar configuration is envisaged, with a 7 cm hill gap and 70 cm valley gap. Three dees, in the valleys, should provide a peak accelerating voltage of 100 kV, allowing a 3rd or 9th harmonic operation. While funding for the machine is still under discussion, a program centered upon the construction of a superconducting model magnet and a full scale rf model was started in 1976. The design features of the model magnet, whose construction is now completed, are reported.

Model Studies for the Superconducting Cyclotron Project in Milan

of the project was completed in June 1976. In the meantime it was also decided that,pending approval and funding of the project, a model construction program would be helpful for i) getting the group acquainted with the problems connected with such a sophisticated machine, especially cryogenics and superconducting coil technology, ii) checking the theoretical calculations used for assessing magnetic fields and R.F. properties, and iii) ultimately reducing the time needed to build the machine in the near future.

Field Measurements on the Milan Superconducting Model Magnet

As a whole, we believe that, as far as magnetic field properties are concerned, the following conclusions can be drawn with a large degree of assurance: i) azimuthal field modulation, as calculated from any saturated pole tip geometry, agrees with data to such an extent that this method can safely be used to predict harmonic amplitudes and phases; ii) absolute values of the average magnetic field can be predicted, even with a rather rough approximation, to within ± 1.%, at least in the range of fields B ¿ 25 kG where pole iron is largely saturated. This holds for inner radii fields and fri ngi ng fi el ds as wel 1; iii) more refined and time-consuming calculations can probably trim down these errors to a few parts per thousand, although, in our belief, with little more advantage from the point of view of a cyclotron early design. As quoted above, all magnetic field measurements stopped in January 1978. They will resume only if the cyclotron will be built, this time with the precise purpose of designing the final iron geometry of the machine. We believe that the availability of the model will enable us to shorten considerably the time needed to define, down to the very last details, the overall structure of the cyclotron.

Beam Extraction Studies for the Proposed Superconducting Cyclotron at the University of Milan

The preliminary extraction scheme described here does not seem, in principle, to offer any major obstacles. Further development should go towards: i) minimizing the problem of adapting the contour of deflectors to the trajectories of different ions, given the rather different orbits scalloping at high and low magnetic fields. ii) minimize the range of movements required for the extraction elements. iii) verify the possihility of insertiont of a third deflector, iiii) verify the possibility of an essentially constant,fixed, gradient for the magnetic channel, in which case a passive channel could be adopted. Work on these issues is in progress, and will be completed as soon as magnetic field data from the 1:6 scale model are available.

Acceleration of H- Ions and Extracted Beam Measurements in the Milan Cyclotron (+)

The characteristics of the proton beam extracted from the Milan AVF cyclotron by H- ion stripping have been studied. Quality and phase measurements were made in an external beam which was obtained without any geometrical definition of the internal H- beam path.