Study of a superconducting 2.5 GeV proton cyclotron as a first step towards a Kaon factory

Abstract A superconducting separate sector cyclotron for accelerating protons from 100 MeV to 2.5 GeV is studied. It is proposed as a first stage, KISS, of a Kaon factory ( K aon factory I sochronous S uperconducting S ector cyclotron). The magnetic guiding field is established by twelve superconducting sector magnets providing mean injection and extraction radii of r 1 = 2.67 m and r 2 = 6 m, respectively. The weight of steel for each magnet is 200 t. Axial focusing is achieved by a reverse field between the magnets in the radial sector region resulting in a large flutter ( F ≈ 4). At larger radii ( r > 4.9 m) an increasing spiral angle ζ ( r ) up to ζ ( r 2 ) = 75° is applied. An accelerating voltage of 10 MV/turn is produced by ten SIN-style rf cavities and one third harmonic flat top cavity of the same type. A slightly enlarged version of the SIN-injector II consisting of a Cockcroft Walton preaccelerator and a 100 MeV conventional separate sector cyclotron is proposed as an injector of KISS. Thus, it seems to be possible to accelerate protons at a current of several milliampere up to 2.5 GeV. By means of a second stage rapid-cycling synchrotron of 100 m radius the energy can be increased to 30 GeV, the expected intensity being still one tenth of that in KISS.