As the demand for radioisotope production increases. the design of the solid targets used for irradiation must be improved in order to take advantage of higher beam currents. To do so, the target's thermal and mechanical properties, and the effects of heat deposition and thermal-stress must be optimized, Finite element methods are used to analyze the steady stare response of the solid target under the heating from beam bombardment, and the mechanical stress resulting from coolant pressure. Results of the analysis are presented and discussed.

In the 14(th) Int. Conf. On Cyc. held at Cape Town, 1995, we reported a 2.5 mA H- cyclotron beam capability using a 28 keV, 15 mA do injection. Baartman pointed out that the upper limit should be about 3.3 mA for our model cyclotron. In order to test whether we can reach such a limit, a cesiated H- source and a 5-electrode extraction system have been developed. More than 20 mA dc beam with a normalized 4 rms emittance of 0.5 pi-mm-mrad has been obtained. As a result, 1.8 mA accelerated rf beam at 0.9 MeV is achieved using 50% duty factor but without injection bunching, equivalent to a 3.6 mA far the full power. The magnet profile of the model cyclotron and its effect on the bunching gain factor at energies 0.3, 0.5 and 0.9 MeV (resp. 1.5, 2.5 and 4.5 turns) were studied.

In the last twenty years we have witnessed a dramatic increase in the demand for accelerator-produced radioisotopes and a corresponding increase in the beam capabilities of the new generations of commercial production cyclotrons. This paper will attempt to trace the changes in the design of external solid target systems for radioisotope production and discuss the many new challenges imposed by pushing the extracted beam currents to one milliampere and beyond, especially as applied in the "MDS Nordion" facility at TRIUMF.

The current solid isotope production targets [1] at TRIUMF can only be used to irradiate metallic materials with high melting points. In order to irradiate liquids, powders, and materials with low melting points, a new encapsulated target is being developed specifically for use on isotope production cyclotrons. This concentrically water-cooled target must withstand a 240 mu A @ 30 MeV proton beam. The target is a round container with a pocket to hold the target material; the target material is encapsulated using a thin foil, which is electron-beam welded onto the target. The cooling and the heat-induced stresses of the target are being analysed using finite element methods. The results will then be compared with actual measurements obtained using surface embedded thermocouples. The paper discusses the results and the current status of the project.

Solid target systems for use with vertically oriented targets are currently used at TRIUMF for radioisotope production. In order to irradiate liquids, powders, and non-electroplatable materials using the newly developed encapsulated target, a new target system for use with horizontally oriented targets is being designed. This target station has a modular assembly consisting of a landing terminal, an irradiation chamber, a manipulator, and an actuator. Targets are pneumatically transferred between the station and the hot cells. The target is positioned in the irradiation orientation by a remotely controlled actuator, which also creates concentric coolant circuit against the back surface of the target. Additional cooling is provided by a forced flow of helium gas over the top surface of the target. This target station can also be used for irradiation of regular solid targets. The paper discusses the detailed design of this target system and the current status of the project

The environment present at commercial facilities for the production of radioisotopes is usually unsuited to that required for truly innovative and cutting-edge research. At TRIUMF, however, a unique relationship exists between a federal research laboratory (TRIUMF) and a commercial producer of radioisotopes (MDS Nordion Inc.) that does allow for both of these aspects. In this partnership, the main role of TRIUMF is to operate the commercial compact cyclotrons and the associated targetry and to produce radioisotopes on the large 520-MeV main cyclotron. MDS Nordion subsequently processes and distributes the radioactive products to customers. TRIUMF`s expertise in cyclotron and targetry technology is constantly being applied to improve the existing isotope production systems. Completely new cyclotron and targetry systems have also been developed for commercial radioisotope production, such as the TR30 cyclotron and its upgrade and the universal encapsulated target system for isotope production.

The implementation of recent ICRP recommendations regarding the reduction of personnel radiation doses has necessitated some drastic changes in the philosophy and method of operation for several commercial cyclotron facilities. In previous years it was not uncommon for some operations personnel to receive 20-50 mSv/year due to the high radiation fields and operating schedule of some of these cyclotron facilities. The new limit commonly being adopted is 20 mSv/year and this has resulted in many of these facilities switching to more stringent operating routines e.g., scheduled preventative programs schedules, longer cooldown periods for repairs, more conservative beam current levels, and significant upgrades to cyclotron and targetry components. At the Nordion/TRIUMF facilities in Vancouver, Canada the recent upgrade of cyclotrons resulting in significantly higher operating beam currents has made the personnel radiation dose issue even more prominent. By a prudent choice of improved shielding schemes, carefully planned preventative maintenance, improvements to the cyclotron and the targetry hardware these problem; have been managed such that individual personnel radiation doses below 10 mSv/year are achieved without compromising production.

Cyclotrons continue to be efficient accelerators for radio-isotope production. In recent years, developments in the accelerator technology have greatly increased the practical beam current in these machines while also improving the overall system reliability. These developments combined with the development of new isotopes for medicine and industry, and a retiring of older machines indicates a strong future for commercial cyclotrons. In this paper we will survey recent developments in the areas of cyclotron technology, and isotope production, as they relate to the new generation of commercial cyclotrons. We will also discuss the possibility of systems capable of extracted energies up to 100 MeV and extracted beam currents of up to 2.0 mA

The use of commercial cyclotron systems for the production of radioisotopes continues to grow on a world-wide scale. Improvements in technology have significantly increased the production capabilities of modern cyclotron-based isotope production facilities. In particular, the change to negative ion acceleration and new high power systems have resulted in dramatic improvements in reliability, increases in capacity, and decreases in personnel radiation dose. As more and more older machines are retired, decisions regarding their replacement are made based on several factors including the market`s potential and the cyclotron system`s abilities. Taking the case of the recently upgraded TR30 cyclotron at TRIUMF/Nordion, the authors investigate the requirements industrial/medical users are likely to impose on future commercial cyclotron systems and the impact this will have on cyclotron technology by the end of the century.

Measurements of the vector analyzing power iT11 in πd elastic scattering at 49 MeV have been performed using a dynamically polarized target and a magnetic spectrometer. Data at seven π+ laboratory scattering angles between 50° and 130° were taken together with a complementary measurement at 60° for π−d elastic scattering. In general, we find agreement with models that include the πN P11 amplitude and disagreement with models that exclude or suppress it.Received 12 October 1993DOI:https://doi.org/10.1103/PhysRevC.49.1715©1994 American Physical Society

Energy spectra of both protons and deuterons emitted following the capture of negative muons by He-3 nuclei have been measured for energies above 15 MeV. A limited number of proton-neutron pairs emitted in coincidence were also observed. A simple plane wave impulse approximation (PWIA) model calculation yields fair agreement with the measured proton energy spectra, but underpredicts the measured rate of deuteron production above our energy threshold by a large factor. A more sophisticated PWIA calculation for the two-body breakup channel, based on a realistic three-body wave function for the initial state, is closer to the deuteron data at moderate energies, but still is significantly lower near the kinematic end point. The proton-neutron coincidence data also point to the presence of significant strength involving more than one nucleon in the capture process at high energy transfer. These results indicate that additional terms in the capture matrix element beyond the impulse approximation contribution may be required to explain the experimental data. Specifically, the inclusion of nucleon-nucleon correlations in the initial or final state and meson exchange current contributions could bring calculations into better agreement with our data. A fully microscopic calculation would thus open the possibility for a quantitative test of multinucleon effects in the weak interaction.

Dickie, W J; Abeysekera, B F; Livera, A; Webster, B; Porter, J K; Stevenson, N R Author Information

Measurements of the vector analyzing power iT11 in pid elastic scattering at 49 MeV have been performed using a dynamically polarized target and a magnetic spectrometer. Data at seven pi+ laboratory scattering angles between 50-degrees and 130-degrees were taken together with a complementary measurement at 60-degrees for pi-d elastic scattering. In general, we find agreement with models that include the piN P11 amplitude and disagreement with models that exclude or suppress it.

Remotely manipulated solid target systems have been developed at TRIUMF for the production of /sup 201/Tl, /sup 67/Ga, /sup 111/In and /sup 57/Co radioisotopes. An extension of these systems to accept a 400 /spl mu/A 30 MeV proton beam has been designed. The design criteria included keeping the temperature of the water-cooled silver face of the target below 140/spl deg/ during irradiation. A combination of computer modeling and actual measurements employing thermocouples indicate the temperature to be significantly lower thereby permitting even higher beam currents. This paper will present these results and conclusions and also summarise the refinements and changes made to the hardware of the target stations and transfer system which feature high radiation hardness components to minimize maintenance and improve reliability.<>