Jobe, R.K.

Paper	Title	Page
MOOCH03	Status of a Linac RF Unit Demonstration for the NLC/GLC X-band Linear Collider	42
	D.C. Schultz, C. Adolphsen, D.L. Burke, J. Chan, S. Doebert, V.A. Dolgashev, J.C. Frisch, R.K. Jobe, D.J. McCormick, C.D. Nantista, J. Nelson, M.C. Ross, T.J. Smith, S.G. Tantawi SLAC, Menlo Park, California D.P. Atkinson LLNL, Livermore, California Y.H. Chin, S. Kazakov, A. Lounine, T. Okugi, N. Toge KEK, Ibaraki
	Designs for a future TeV scale electron-positron X-band linear collider (NLC/GLC) require main linac units which produce and deliver 450 MW of rf power at 11.424 GHz to eight 60 cm accelerator structures. The design of this rf unit includes a SLED-II pulse compression system with a gain of approximately three at a compression ratio of four, followed by an overmoded transmission and distribution system. We have designed, constructed, and operated such a system as part of the 8-Pack project at SLAC. Four 50 MW X-band klystrons, running off a common 400 kV solid-state modulator, drive a dual-moded SLED-II pulse compression system. The compressed power is delivered to structures in the NLCTA beamline. Four 60 cm accelerator structures are currently installed and powered, with four additional structures and associated high power components available for installation late in 2004. We describe the layout of our system and the various high-power components which comprise it. We also present preliminary data on the processing and initial high-power operation of this system.
	Video of talk
	Transparencies
MOPLT107	Nanosecond-timescale Intra-bunch-train Feedback for the Linear Collider: Results of the FONT2 Run	785
	P. Burrows, T. Hartin, S.M. Hussain, S. Molloy, G.R. White Queen Mary University of London, London C. Adolphsen, J.C. Frisch, L. Hendrickson, R.K. Jobe, T. Markiewicz, D.J. McCormick, J. Nelson, M.C. Ross, S. Smith, T.J. Smith SLAC, Menlo Park, California R. Barlow, M. Dufau, A. Kalinin CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Myatt, C. Perry OXFORDphysics, Oxford, Oxon
	We report on experimental results from the December 2003/January 2004 data run of the Feedback On Nanosecond Timescales (FONT) experiment at the Next Linear Collider Test Accelerator at SLAC. We built a second-generation prototype intra-train beam-based feedback system incorporating beam position monitors, fast analogue signal processors, a feedback circuit, fast-risetime amplifiers and stripline kickers. We applied a novel real-time charge-normalisation scheme to account for beam current variations along the train. We used the system to correct the position of the 170 nanosecond-long bunchtrain at NLCTA, in both 'feed forward' and 'feedback' modes. We achieved a latency of 53 nanoseconds, representing a significant improvement on FONT1 (2002), and providing a demonstration of intra-train feedback for the Linear Collider.
THPLT154	Design of an X-ray Imaging System for the Low-Energy Ring of PEP-II	2816
	A.S. Fisher, D. Arnett, H. De Staebler, S. Debarger, R.K. Jobe, D. Kharakh, D.J. McCormick, M. Petree, M.C. Ross, J. Seeman, B. Smith SLAC, Menlo Park, California J. Albert, D. Hitlin CALTECH, Pasadena, California J. Button-Shafer, J.A. Kadyk LBNL, Berkeley, California
	An x-ray beam-size monitor for positrons in the low-energy ring (LER) of the PEP-II B Factory at SLAC is being designed to accommodate the present 2-A, 3.1-GeV beam and anticipated currents of up to 4.7 A. The final photon stop of an arc will be rebuilt to pass dipole radiation through cooled apertures to optics 17 m from the source. Zone-plate imaging there can achieve a resolution of 6 microns, compared to 35 for a pinhole camera. Two multilayer x-ray mirrors precede the zone plate, limiting the bandwidth to 1%, in order to avoid chromatic blurring and protect the zone plate. Despite the narrow bandwidth, the zone plate?s larger diameter compared to a pinhole camera allows for a comparable photon flux. We will image all 1700 LER bunches and also measure them individually, searching for variations along the train due to electron-cloud and beam-beam effects, using a scanning detector conceptually derived from a wire scanner. A mask with three narrow slots at different orientations will scan the image to obtain three projections. In one passage, signals from a fast scintillator and photomultiplier will be rapidly digitized and sorted to profile each bunch.