PAC07 - List of Authors (McCormick, D. J.)

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

McCormick, D. J.

Paper	Title	Page
THOAC03	Measurement of the Beam's Trajectory Using the Higher Order Modes it Generates in a Superconducting Accelerating Cavity	2642
	S. Molloy, J. C. Frisch, J. May, D. J. McCormick, M. C. Ross, T. J. Smith SLAC, Menlo Park, California N. Baboi, O. Hensler, R. Paparella, L. M. Petrosyan DESY, Hamburg N. E. Eddy, L. Piccoli, R. Rechenmacher, M. Wendt Fermilab, Batavia, Illinois O. Napoly, C. Simon CEA, Gif-sur-Yvette
	Funding: US DOE Contract #DE-AC02-76SF00515 It is well known that an electron beam excites Higher Order Modes (HOMs) as it passes through an accelerating cavity~[panofsky68]. The properties of the excited signal depend not only on the cavity geometry, but on the charge and trajectory of the beam. It is, therefore, possible to use these signals as a monitor of the beam's position. Electronics were installed on all forty cavities present in the FLASH~[flashref] linac in DESY. These electronics filter out a mode known to have a strong dependence on the beam's position, and mix this down to a frequency suitable for digitisation. An analysis technique based on Singular Value Decomposition (SVD) was developed to calculate the beam's trajectory from the output of the electronics. The entire system has been integrated into the FLASH control system.
	Slides
THPMS049	Investigations of the Wideband Spectrum of Higher Order Modes Measured on TESLA-style Cavities at the FLASH Linac	3100
	S. Molloy, C. Adolphsen, K. L.F. Bane, J. C. Frisch, Z. Li, J. May, D. J. McCormick, T. J. Smith SLAC, Menlo Park, California N. Baboi DESY, Hamburg N. E. Eddy, L. Piccoli, R. Rechenmacher Fermilab, Batavia, Illinois R. M. Jones UMAN, Manchester
	Funding: US DOE Contract #DE-AC02-76SF00515 Higher Order Modes (HOMs) excited by the passage of the beam through an accelerating cavity depend on the properties of both the cavity and the beam. It is possible, therefore, to draw conclusions on the inner geometry of the cavities based on observations of the properties of the HOM spectrum. A data acquisition system based on two 20 GS/s, 6 GHz scopes has been set up at the FLASH facility, DESY, in order to measure a significant fraction of the HOM spectrum predicted to be generated by the TESLA cavities used for the acceleration of its beam. The HOMs from a particular cavity at FLASH were measured under a range of known beam conditions. The dipole modes have been identified in the data. 3D simulations of different manufacturing errors have been made, and it has been shown that these simulations can predict the measured modes.
THPMS055	Beam Dynamics Measurements for the SLAC Laser Acceleration Experiment	3115
	J. E. Spencer, E. R. Colby, R. Ischebeck, D. J. McCormick, C. Mcguinness, J. Nelson, R. J. Noble, C. M.S. Sears, R. Siemann SLAC, Menlo Park, California T. Plettner Stanford University, Stanford, Califormia
	Funding: Work supported by U. S. Dept. of Energy contract DE-AC02-76SF00515. The NLC Test Accelerator (NLCTA) at SLAC was built to address various beam dynamics issues for the Next Linear Collider. An S-Band RF gun has been installed with diagnostics and a low energy spectrometer (LES) at 6 MeV together with a large-angle extraction line at 60 MeV. This is followed by a matching section, buncher and final focus for the laser acceleration experiment, E163. The laser-electron interaction area is followed by a broad range (2\%), high resolving power (10⁴) spectrometer (HES) for electron bunch analysis. Emittance compensating solenoids and the LES are used to tune for best operating point and match to the linac. Optical symmetries in the design of the 25.5^° extraction line provide 1:1 phase space transfer without use of sextupoles for a large, 6D phase space volume and range of input conditions. Spot sizes of a few microns at the IP (or HES object) allow tests of microscale structures as well as high resolving power at the image of the HES. Tolerances, tuning sensitivities and diagnostics are discussed together with the latest commissioning results and their comparison to design expectations.
FRPMS073	Picosecond Bunch Length and Energy-z Correlation Measurements at SLAC's A-Line and End Station A	4201
	S. Molloy, P. Emma, J. C. Frisch, R. H. Iverson, D. J. McCormick, M. Woods SLAC, Menlo Park, California V. Blackmore OXFORDphysics, Oxford, Oxon M. C. Ross Fermilab, Batavia, Illinois S. Walston LLNL, Livermore, California
	Funding: US DOE Contract #DE-AC02-76FS00515 We report on measurements of picosecond bunch lengths and the energy-z correlation of the bunch with a high energy electron test beam to the A-line and End Station A (ESA) facilities at SLAC. The bunch length and the energy-z correlation of the bunch are measured at the end of the linac using a synchrotron light monitor diagnostic at a high dispersion point in the A-line and a transverse RF deflecting cavity at the end of the linac. Measurements of the bunch length in ESA were made using high frequency diodes (up to 100 GHz) and pyroelectric detectors at a ceramic gap in the beamline. Modelling of the beam's longitudinal phase space through the linac and A-line to ESA is done using the 2-dimensional tracking program LiTrack, and LiTrack simulation results are compared with data. High frequency diode and pyroelectric detectors are planned to be used as part of a bunch length feedback system for the LCLS FEL at SLAC. The LCLS also plans precise bunch length and energy-z correlation measurements using transverse RF deflecting cavities.
FRPMN090	A Prototype Energy Spectrometer for the ILC at End Station A in SLAC	4285
	A. Lyapin, F. Gournaris, B. Maiheu, D. J. Miller, M. Wing UCL, London C. Adolphsen, R. Arnold, C. Hast, D. J. McCormick, Z. M. Szalata, M. Woods SLAC, Menlo Park, California S. T. Boogert, G. E. Boorman Royal Holloway, University of London, Surrey M. V. Chistiakova, Yu. G. Kolomensky, E. Petigura, M. Sadre-Bazzaz UCB, Berkeley, California V. N. Duginov, S. A. Kostromin, N. A. Morozov JINR, Dubna, Moscow Region M. Hildreth Notre Dame University, Notre Dame, Iowa H. J. Schreiber, M. Viti DESY Zeuthen, Zeuthen M. Slater, M. Thomson, D. R. Ward University of Cambridge, Cambridge
	The main physics programme of the international linear collider requires a measurement of the beam energy with a relative precision on the order of 10^-4 or better. To achieve this goal a magnetic spectrometer using high resolution beam position monitors (BPM) has been proposed. A prototype spectrometer chicane using 4 dipole magnets is currently under development at the End Station A in SLAC, intending to demonstrate the required stability of this method and investigate possible systematic effects and operational issues. This contribution reports on the successful commissioning of the beam position monitor system and the resolution and stability achieved. Also, the initial results from a run with a full spectrometer chicane are presented.
FRPMS049	Resolution of a High Performance Cavity Beam Position Monitor System	4090
	S. Walston, C. C. Chung, P. Fitsos, J. Gronberg LLNL, Livermore, California S. T. Boogert Royal Holloway, University of London, Surrey J. C. Frisch, S. Hinton, J. May, D. J. McCormick, S. Smith, T. J. Smith, G. R. White SLAC, Menlo Park, California H. Hayano, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki Yu. G. Kolomensky, T. Orimoto UCB, Berkeley, California P. Loscutoff LBNL, Berkeley, California A. Lyapin, S. Malton, D. J. Miller UCL, London R. Meller Cornell University, Department of Physics, Ithaca, New York M. C. Ross Fermilab, Batavia, Illinois M. Slater, M. Thomson, D. R. Ward University of Cambridge, Cambridge V. Vogel DESY, Hamburg
	International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved – ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. A metrology system for the three BPMs was recently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame and has demonstrated that the three BPMs behave as a rigid-body to less than 5 nm. To date, we have demonstrated a BPM resolution of less than 20 nm over a dynamic range of ± 20 microns.