A compact cyclotron based slow positron beam and a new positron pulsing system

A new positron pulsing system has been developed for the first time using an induction cavity. The slow positron beam is provided by using a compact cyclotron. In order to use the slow positron beam from the compact cyclotron for the analyses of material surfaces such as variable-energy positron lifetime spectroscopy, we have developed a new positron pulsing system. In the new system, slow positron beam bunching is performed by applying an induction cavity instead of a usual rf cavity. The induction cavity makes it possible to produce any kind of electric field change according to time. Hence the bunching efficiency of the induction cavity should be higher than that of rf cavity which can produce only sine curves electric field change according to time. In a preliminary slow positron beam bunching test using the induction cavity, a pulse width (FWHM) of about 1 ns has been achieved. A fine tuning for achieving a pulse width of 150 ps is in progress. Another new compact cyclotron and a new slow positron beam facility are also under construction next to the present ones. The design of the new facility will be also reported.