The Spallation Neutron Source project

Abstract

The SNS is a "joint-venture" project of five DOE National Laboratories, aimed at building the world's most powerful accelerator-based pulse spallation source. At its planned 2 MW operation, it will produce neutron fluxes at least a factor of ten greater than Rutherford Appleton Laboratory's ISIS, currently the world's leading spallation source. The current design of the SNS, shown in Figure 1, calls for 600 ns pulses of 1 GeV protons striking a liquid mercury target at a 60 Hz rate. Room-temperature and cryogenic moderators produce beams of slow neutrons suitable for materials research. Responsibility for system components is as follows: LBNL will provide the high-brightness H -ion source, transport structures and a 2.5-MeV RFQ accelerator; Los Alamos will build linacs to bring the beam to the full energy of 1 GeV; Brookhaven will build the accumulator ring to compress the 1 ms linac pulse into the sharp pulse delivered to the target; ≈1200 turns will be injected, storing 2x10 14 protons in the ring, which are extracted in a single turn; Oak Ridge will provide the mercury target systems and all conventional facilities; and Argonne and Oak Ridge are coordinating the design of at least 10 neutron-scattering instruments to be provided as the initial suite of experiment stations. The project is formally underway, having been approved and funded by DOE and the US Congress for a construction start in FY99. Neutron beams will be available for users in FY06. FIGURE 1: Schematic layout of SNS BEAM REQUIREMENTSNeutron scattering requires low energy (< milli-electron volt) neutrons, to obtain De Broglie wavelengths commensurate with the size of the structures being studied.

Accelerator complex for the joint project of KEK/JHF and JAERI/NSP

“…The several-GeV booster synchrotron is indispensable for the high-intensity several 10-GeV beams. This is one of the reasons why we are going to use the RCS for the Phase-I neutron source in contrast to the SNS project [19] and the ESS project [20]. If it turns out that the RCS scheme is more promising than the SR scheme, we will upgrade the Phase-I RCS to 6 GeV and will build one more 6-GeV RCS in order to provide a several-MW beam.…”

Superconductive test cavity for the ESS

“…Higher repetition rates such as 50 Hz for the ESS design [1] and 60 Hz at SNS [4] or 75 Hz for the CERN Neutrino Factory design [5] will require a close look into the mechanical resonances of the cavities. Such mechanical resonances can influence the phase behaviour of the cavity during a pulse, which can hardly be compensated by a good control system, even if enough additional power is available.…”