Design report: the proposed Recirculating Linear Accelerator (RLA) at SLAC

Abstract

The high energy physics objectives and a general description of the Recirculating Linear Accelerator (RLA) including lattice, orbits, and beam transfer parameters; magnet system; vacuum ontrol; beam switchyard and slow extraction; conventional facilities; and schedule and cost ters may be summarized as follows: A beam energy approximately double that of the present SLAC accclerartor would be achieved by a sequence that consists of first-pass acceleration through the twomile acceleration, beam storage in the recirculator, and reinjection and second-pass acceleration of the beam. In an alternate mode of operation, a stored one-pass beam having an energy up to about 20 GeV could be gradually extracted from the recirculator for use in high duty cycle experiments (up to 7%, as compared with the present 0.06%). The maximum recirculation energy is 17 to 20 GeV, depending on the number of electrons stored. Beam-energy losses of approximately 130 MeV each turn due to two sectors (200 meters) of standard SLAC accelerator sections operating at the standard s will be powered by a special klystron now under development yielding 500 kW peak power at a duty cycle of about 10%. The repetition rate of the power source is 43,000 pps, and the recirculating period is 23 microseconds, corresponding to tne total storage path of 6963 meters. The initial beam energy attainable at SLAC by this method is estimated to be about 42 GeV, and future increases are possible. Some of these would occur naturally as part of the program at SLAC of increases in klystron power. A further substantial change might occur in the future by the installation of accelerator sections which can compensate for the synchrotron radiation loss at storage energies as high as 25 GeV. A combination of these improvements might eventually increase the RLA energy up to 60 GeV. (WHK)