Heavy Ion Accelerators

Abstract

From memorial lectures given recently in honour of pioneering personalities of nuclear physics, one gain the impression that electrons and light ions, emitted by radioactive samples, were adequate radiation sources to probe the nuclear structure and that experimental limitations existed primarily in the detecting instruments of the time. Ideas for electrotechnical devices for accelerating various charged particle species are said to have been described in the liiterature, but more as a principle rather than a usable tool. Moreover, it was said that D. O. Lawrence, the famous inventor of tbe cyclotron in 1932, used nuclear reactions to demonstrate the accelerating performance of his rapidly growing machines rather than immediately commissioning one machine a a working tool for nuclear physics experiments.

From a more modern standpoint the technical background did not exist in those days to build beam production machines. And it was not until World War II and after that nuclear data were so urgently needed that any conceivable technical effort went into the development of particle accelerators. This is specificallyy true for high-power radiofrequency (rf) amplifiers whicb then became available from radar applications or were specifically developed for building large ion linear accelerators for breeding fissile material.

Along with the vacuum, high voltage and rf developments of the post war nuclear age, two theoretical inventions were indispensable for building large accelerators: the principle phase focussing in rf linear accelerators and the strong focussing of particle beams in linear and circular accelerators. In the mid-1950s all tools were on hand to build electron, proton and heavy-ion accelerators as nuclear and high energy physics experiments demanded.

Rolf Wideröe, in his later talks, called tbe accelerators a ‘child of physics and electrical engineering’. However, this interdisciplinary view did not exist until the late forties. Before this, accelerator were homemade device in nuclear physics institutes. Physicists wound magnet coils by themselves, and designed their own vacuum pumps and rf tubes. Today, the larger accelerators are still planned for a specific research goal in the nuclear physics institutes. Electrical engineers take part in the design tage, and all components are entirely subcontracted to industry.