Preliminary design studies of a 100 MeV H-/H+ Linac as injector for SNS synchrotron/ADS Linac

It is proposed to construct a spallation neutron source (SNS) at Centre for Advanced Technology (CAT) based on a 1 GeV proton synchrotron with 100 MeV H- Linac injector. Additionally, the Linac can form the first 100 MeV part of a 1 GeV proton Linac to be built in future for accelerator driven system (ADS) applications. We are exploring a configuration of the 100 MeV Linac which will consist of an H- ion source, a 4-6 MeV RFQ followed either by a 20 MeV drift tube Linac (DTL) and 100 MeV separated function drift tube Linac (SDTL) or a coupled cavity drift tube Linac (CCDTL) structure. In this paper, we present the results of our preliminary physics design studies of the RFQ-SDTL, RFQ-CCDTL and RFQ-DTL-SDTL configurations. The design of the 4.5 MeV RFQ is discussed along with the matching sections between the RFQ-SDTL-DTL and RFQ-CCDTL. The choice of the accelerator configuration and that of various parameters of the individual accelerator structures under consideration are discussed. The design objectives are to arrive at a configuration which eases heat removal for CW operation and which is less prone to halo formation in order to reduce the beam loss at higher energies. (author)