Accelerator Physics Video Conference Minutes, 6/20/2000 Participants: BNL: N. Catalan-Lasheras, A. Fedotov, Y.Y. Lee, N. Malitsky, D. Raparia, B. Weng JLAB: G. Kraft LANL: N. Bultman, D. Gurd, A. Regan, R. Schafer, J. Stovall LBNL: R. Keller, J. Staples ORNL: S. Danilov, G. Dodson, J. Galambos, J. Holmes, D. Jeon, S. Kim, J. Wei, M. White, K. Woody 1a) 2nd Target Layout Decision D. Raparia discussed RTBT redesign to incorporate the 2nd target station. To provide additional protection to workers in the target station area, it is proposed to move a 3 meter block of iron into the RTBT. Due to the attenuation factor of the iron, it is estimated that incident bunches of 10^14 protons would result in only 0.2 mRad after the iron. 1b) H-minus Stripping in the RF Linac Deepak reported that it would require an E field of 162 MV/m to cause H-minus stripping at the level of the 0.3 T dipole in the injection chicane. Thus, H-minus stripping in the linac due to E fields should not be a problem. 2) Mini-ASAC Comments and Report The response of the ASAC committee to the 1 klystron/cavity architecture was very positive. They find this much more robust than the previous use of multiple cavities/ klystron and fast phase shifters. They see no identifiable risks in the present design. The only suggestion for cutting cost was to buy the waveguides more cheaply in Germany. Concerns include the 4 meter drift between the warm and cold linac sections, which was not included in the simulations. The end-to-end beam dynamics, which starts with a waterbag distribution at present, will be repeated using simulated RFQ output distributions obtained by John Staples. The 550 kW klystron power rating is marginal, and may be too weak to get full performance from the good cavities. The present linac design results in an overall cost increase of between $8M and $15M when compared to the March baseline. It may be possible to obtain some decrease in this figure from conventional facilities through reduced air conditioning requirements. 3) RF Instrumentation Requirements for the RFQ and Associated Waveguide This will be coordinated between LANL and LBNL. 4) EPAC Meeting SNS Papers: BNL ~25, JLAB 0, LANL 2, LBNL 2, ORNL 4 See EPAC Proceedings for details. 5) Miscellaneous LANL and LBNL discussed the use of steering windings in the MEBT for carrying out a DTL acceptance scan. Present range of MEBT steering windings gives +/- 5 mR. The design of these windings, as well as of the main quadrupole windings and iron cores, has been completed, and the parts are being constructed. Methods of achieving greater deflections are being discussed. A global coordinate system for the SNS drawings to be used for construction was discussed. It was agreed that the system should place SNS in the region of positive coordinate values, be of a right-handed orientation, and use metric units. 6) Next Video Conference The next video conference will be on Tuesday, 7/11/2000.