Invited Paper-Synchrocyclotron Conversion

The possibility of increasing the output of fm cyclotrons is being explored simultaneously in many laboratories. Space charge seems to be the limiting factor. Practically every laboratory is investigating a form of hooded source known as the Livingston, calutron or Oak Ridge source. The ions must clear such a source so higher dee voltages are needed. The higher dee voltage is desirable in any case since the beam usually increases as some power of this voltage (if the repetition rate is increased correspondingly). The theoretical picture indicates a variation between V and V2. Some fm cyclotrons will try to increase performance by this method alone. Others will include all the possible improvements including a complete sector field near isochronism which will provide strong vertical focusing and reduce the frequency swing. The largest machines will probably try to achieve their goal by small sectors near the source and somewhat lareer limited radii sectors on the poles (with an unchanged radial profile). The status of these efforts is reviewed and some data on the Berkeley model program is given. It appears that most fm cyclotrons will eventually be partially or wholly converted to sector focused synchrocyclotrons.