AVF cyclotron

Ion beams are useful to simulate the environment in space, where semiconductor devices are exposed to high-energy heavy-ion impact. Incorrect operation of semiconductor devices such as single-event upset results from the heavy-ion irradiation. The cocktail ion families of MjQ = 4 and 5, available at the JAERI AVF cyclotron facility [24], are frequently utilized to investigate the tolerance of the semiconductor devices to the radiation, and to survey highly radiation-tolerant semiconductor devices appearing in the market. Efficiency of the radiation-tolerance testing for thousands of kinds of semiconductor devices has been totally improved by the cocktail acceleration technique. 

Commissioning of a new microbeam system is in progress to improve the resolution of the high-energy heavy-ion microbeam. The new microbeam system has been installed on another vertical beam line of the JAERI AVF cyclotron. A schematic diagram of the microbeam system is shown in Fig. 12. The spot size of hundreds of MeV heavy-ion beams is expected to be reduced to less than 1 pm by using a quadruplet of quadrupole lenses in combination with a series of slits. The microbeam system is also equipped with a single-ion hit system. 

A heavy-ion microbeam provides a unique way to control the number of particles traversing individual cells and localization of dose within the cell. A collimated heavy-ion microbeam apparatus has been installed in a beam line from the AVF cyclotron to develop a novel cell surgery technique [127] (Fig. 34) (Table 5). 

Figure 34 Schematic diagram of microbeam system for biological study. An ion beam from an AVF cyclotron is collimated by collimators and a tantalum disk with microaperture with a diameter of 5-250 pm. The collimated ion beam passes through the room air to a target that is set on the micropositioning stage of an optical microscopic system.

I., Yamamoto, Y., Oshima, N. and Ito, Y. (1995). Slow positron production using the RIKEN AVF cyclotron. Applied Surface Science 85 165-171. 

There is a wide variety of AVF cyclotrons in operation regarding the types of the accelerated particles and the construction features. Detailed information can be found in the proceedings of the series of International Conferences on Cyclotrons (Dutto and Craddock 1993 Cornell 1996 Baron and Lieuvin 1999). 

The velocity of a particle moving in the AVF cyclotron has a radial component which reaches maximum when the orbit crosses the circular orbit (see O Fig. 50.18). Since the field varies as a function of 6, there is an azimuthal component Bg and therefore there is a force F acting upon the particle. This force can be expressed as... 

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