Beam Chopper and RF Kicker Systems for the TR24 Cyclotron Injection Line

Abstract

The ability to switch ion beams on and off quickly is a key point in proton therapy that can be achieved
by means of electrical actions. A beam chopper system has first been developed to fulfill this function on
the TR24 Cyclotron of the Cyrce Platform at the IPHC Laboratory. In addition, the capability of discarding ´
one ion beam bunch over two is of great interest in the context of the CMS (Compact Muon Solenoid)
detector as it allows us to make tests close to the LHC (Large Hadron Collider at CERN) bunch repetition
rate (40 MHz), the cyclotron RF frequency being 85.085 MHz. A second kicker (the so-called RF kicker) has
been developed and installed in place of the first one to fulfill both requirements. This article discusses the
sizing and characteristics of these two systems that were consecutively installed on the injection line of the
TR24 cyclotron. The first system reported uses fast static high-voltage switches while the second one uses
an RF resonator to either populate or depopulate the phase acceptance of the cyclotron. To our knowledge,
this second system used in this specific context has not yet been reported in the literature.