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B. O’Shea

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Last Name: O’Shea

Full Name: B. O’Shea

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3 papers
title: Experiment to Measure Ramped Electron Bunches at the UCLA Neptune Laboratory Using a Transverse Deflecting Cavity
format: conference procceeding
conference: 12th Advanced Accelerator Concepts Workshop
year: 2006
5 authors: R. J. England | D. Alesini | B. O’Shea | J. B. Rosenzweig | G. Travish
abstract: A proof of principle experiment is underway at the UCLA Neptune laboratory to test the concept of generating linearly ramped relativistic electron bunches (rising in density from head to tail followed by a sharp cutoff) by using a sextupole-corrected dogleg section as a bunch compressor. Bunches with this structure have been predicted to be ideal for use as a plasma wake-field drive beam. The diagnostic being developed to measure the time profile of the beam is an X-Band (9.6 GHz) deflecting cavity. The recently completed cavity is a 9-cell standing wave structure operating in a TM110-like mode, designed to measure the temporal structure of the 2 to 10 ps, 14 MeV electron bunches generated by the Neptune S-band photoinjector and plane-wave transformer (PWT) accelerator beamline, with 50 fs resolution. We discuss the experimental plan for the ramped bunch experiment and present preliminary data related to the tuning and operation of the deflecting cavity.
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title: X-Band Dipole Mode Deflecting Cavity for the UCLA Neptune Beamline
format: conference procceeding
conference: 2005 Particle Accelerator Conference
year: 2005
5 authors: R. J. England | B. O’Shea | J. B. Rosenzweig | G. Travish | D. Alesini
abstract: We report progress on the design and construction of a nine-cell cavity operating in a TM110-like dipole mode for use as a temporal diagnostic of the 14 MeV, 300 pC electron bunches generated at the UCLA Neptune Laboratory linear accelerator, with an anticipated temporal resolution of 50 fs at a peak input power of 50 kW. The cavity is a center-fed standing-wave pi-mode structure, operating at 9.6 GHz, and incorporating a knife-edge and gasket assembly which minimizes the need for brazing or welding. Results of initial RF testing of the prototype cavity are discussed and compared with simulation results obtained using the commercial code HFSS.
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title: The New Photoinjector for the Fermi Project
format: journal article
year: 2007
14 authors: G. D’Auria | D. Bacescu | L. Badano | F. Cianciosi | P. Craievich | M. Danailov | G. Penco | L. Rumiz | M. Trovo’ | A. Turchet | H. Badakov | A. Fukusawa | B. O’Shea | J.B. Rosenzweig
abstract: FERMI@elettra is a single-pass FEL user facility covering the spectral range 100-10 nm. It will be located near the Italian third generation Synchrotron Light Source facility ELETTRA and will make use of the existing 1.0 GeV normal conducting Linac [1]. To obtain the high beam brightness required by the project, the present Linac electron source will be substituted with a photocathode RF gun now under development in the framework of a collaboration between Sincrotrone Trieste (ST) and Particle Beam Physics Laboratory (PBPL) at UCLA. The new gun will use an improved design of the 1.6 cell accelerating structure already developed at PBPL, scaled to 2998 MHz. We expect that the new gun design will allow a beam brightness increase by a factor 3-4 over the older version of the device. Some technical choices of the new design, including the enhancement of the mode separation, removal of the RF tuners, full cell symmetrization to limit the dipole and quadrupole RF field as well as an improved solenoid yoke design for multipole field corrections, will be discussed.
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