EPAC08 - List of Authors (Calaga, R.)

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Calaga, R.

Paper	Title	Page
MOPC057	R&D Energy Recovery Linac at Brookhaven National Laboratory	193
	V. Litvinenko, D. Beavis, I. Ben-Zvi, M. Blaskiewicz, A. Burrill, R. Calaga, P. Cameron, X. Chang, K. A. Drees, G. Ganetis, D. M. Gassner, H. Hahn, L. R. Hammons, A. Hershcovitch, H.-C. Hseuh, A. K. Jain, A. Kayran, J. Kewisch, R. F. Lambiase, D. L. Lederle, G. J. Mahler, G. T. McIntyre, W. Meng, T. C. Nehring, B. Oerter, C. Pai, D. Pate, D. Phillips, E. Pozdeyev, T. Rao, J. Reich, T. Roser, T. Russo, K. Smith, J. E. Tuozzolo, D. Weiss, N. Williams, K. Yip, A. Zaltsman BNL, Upton, Long Island, New York H. Bluem, M. D. Cole, A. J. Favale, D. Holmes, J. Rathke, T. Schultheiss AES, Medford, NY J. R. Delayen, L. W. Funk, H. L. Phillips, J. P. Preble Jefferson Lab, Newport News, Virginia
	Collider Accelerator Department at BNL is in the final stages of developing the 20-MeV R&D energy recovery linac with super-conducting 2.5 MeV RF gun and single-mode super-conducting 5-cell RF linac. This unique facility aims to address many outstanding questions relevant for high current (up to 0.5 A of average current), high brightness energy-recovery linacs with novel Zigzag-type merger. We present the performance of the R&D ERL elements and detailed commissioning plan.
TUPP065	Experimental Study of the Electron Cloud Instability in the CERN-SPS	1688
	G. Rumolo, G. Arduini, E. Benedetto, E. Métral, G. Papotti, E. N. Shaposhnikova CERN, Geneva R. Calaga BNL, Upton, Long Island, New York B. Salvant EPFL, Lausanne
	The electron cloud instability limits the performance of many existing proton and positron rings. A simulation study carried out with the HEADTAIL code revealed that the threshold for its onset decreases with increasing beam energy, if the 6D emittance of the bunch is kept constant and the longitudinal matching to the bucket is preserved. Experiments have been carried out at the CERN-SPS to study the dependence of the vertical electron cloud instability on the energy and on the beam size. The reduction of the physical transverse emittance as a function of energy is considered in fact to be the main reason for the unusual dependence of this instability on energy.
TUPP066	CERN SPS Impedance in 2007	1691
	E. Métral, G. Arduini, T. Bohl, H. Burkhardt, F. Caspers, H. Damerau, T. Kroyer, H. Medina, G. Rumolo, M. Schokker, E. N. Shaposhnikova, J. Tuckmantel CERN, Geneva R. Calaga BNL, Upton, Long Island, New York B. Salvant EPFL, Lausanne B. Spataro INFN/LNF, Frascati (Roma)
	Each year several measurements of the beam coupling impedance are performed in both longitudinal and transverse planes of the CERN Super Proton Synchrotron to keep track of its evolution. In parallel, after the extensive and successful campaign of identification, classification and cure of the possible sources of (mainly longitudinal) impedance between 1998 and 2001, a new campaign (essentially for the transverse impedance this time) has started few years ago, in view of the operation of the SPS with higher intensity for the LHC luminosity upgrade. The present paper summarizes the results obtained from the measurements performed over the last few years and compares them to our predictions. In particular, it reveals that the longitudinal impedance is reasonably well understood and the main contributors have already been identified. However, the situation is quite different in the transverse plane: albeit the relative evolution of the transverse impedance over the last few years can be well explained by the introduction of the nine MKE kickers necessary for beam extraction towards the LHC, significant contributors to the SPS transverse impedance have not been identified yet.
TUPP067	Transverse Mode-coupling Instability in the CERN SPS: Comparing MOSES Analytical Calculations and HEADTAIL Simulations with Experiments in the SPS	1694
	B. Salvant EPFL, Lausanne G. Arduini, E. Métral, G. Papotti, G. Rumolo, R. J. Steinhagen, R. Tomas CERN, Geneva R. Calaga BNL, Upton, Long Island, New York
	Since 2003, single bunches of protons with high intensity (1.2·10¹¹ protons) and low longitudinal emittance (0.2 eVs) have been observed to suffer from heavy losses in less than one synchrotron period after injection at 26 GeV/c in the CERN Super Proton Synchrotron (SPS) when the vertical chromaticity is corrected. Understanding the mechanisms underlying this instability is crucial to assess the feasibility of an anticipated upgrade of the SPS, which requires bunches of 4·10¹¹ protons. Analytical calculations from MOSES and macroparticle tracking simulations using HEADTAIL with an SPS transverse impedance modelled as a broadband resonator had already qualitatively and quantitatively agreed in predicting the intensity threshold of a fast instability. A sensitive frequency analysis of the HEADTAIL simulations output was then done using SUSSIX, and brought to light the fine structure of the mode spectrum of the bunch coherent motion. A coupling between the azimuthal modes -2 and -3 was clearly observed to be the reason for this fast instability. The aim of the present paper is to compare the HEADTAIL simulations with dedicated measurements performed in the SPS in 2007.
WEPP007	Crab Compensation for LHC Beams	2536
	R. Calaga BNL, Upton, Long Island, New York Y. Sun, R. Tomas, F. Zimmermann CERN, Geneva
	An R&D program to establish a road map for the installation of crab cavities in the LHC is rapidly advancing. Both local and global crab schemes are under investigation to develop cavities that will be compatible with LHC optics and meet aperture requirements. The design of a prototype TM110 cavity and pertinent RF requirements including impedance estimates and damping are discussed. Some alternate cavity designs are also explored. The required optics modifications to accommodate the crab cavities and some particle stability studies are presented.
WEPP008	Localizing Sources of Horizontal Orbit Oscillations at RHIC	2539
	R. Calaga, R. J. Michnoff, T. Satogata BNL, Upton, Long Island, New York
	Horizontal oscillations of the closed orbit at frequencies around 10Hz are observed at RHIC. These oscillations lead to beam beam offsets at the collision point, resulting in emittance growth and reduced luminosity. An approach to localize the sources of these vibrations using a special mode of RHIC turn-by-turn BPM data is presented. Data from the 2005-06 are analyzed to spatially resolve the location of the dominant sources.
WEPP025	Optics Correction in the LHC	2572
	R. Tomas, M. Aiba, G. Vanbavinckhove CERN, Geneva R. Calaga BNL, Upton, Long Island, New York A. Morita KEK, Ibaraki
	Optics correction in the LHC is challenged by the tight aperture constrains and the demand of a highly performing BPM system. To guarantee that the LHC optics remains within a maximum allowable beta-beating of 20% several methods are being investigated through computer simulations and experiments at existing hadron machines. A software package to consolidate the implementation of the various techniques during LHC operation is underway (or nearing completion)
WEPP019	RHIC Polarized Proton Performance in Run-8	2566
	C. Montag, N. P. Abreu, L. Ahrens, M. Bai, D. S. Barton, A. Bazilevsky, J. Beebe-Wang, M. Blaskiewicz, J. M. Brennan, K. A. Brown, D. Bruno, G. Bunce, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, K. A. Drees, A. V. Fedotov, W. Fischer, G. Ganetis, C. J. Gardner, J. W. Glenn, T. Hayes, H. Huang, P. F. Ingrassia, A. Kayran, J. Kewisch, R. C. Lee, V. Litvinenko, A. U. Luccio, Y. Luo, W. W. MacKay, Y. Makdisi, N. Malitsky, G. J. Marr, A. Marusic, R. J. Michnoff, J. Morris, B. Oerter, H. Okada, F. C. Pilat, P. H. Pile, G. Robert-Demolaize, T. Roser, T. Russo, T. Satogata, C. Schultheiss, M. Sivertz, K. Smith, S. Tepikian, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S. Y. Zhang BNL, Upton, Long Island, New York
	During Run-8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin-polarized proton beams at two interaction regions. Helical spin rotators at these two interaction regions were used to control the spin orientation of both beams at the collision points. Physics data were taken with different orientations of the beam polarization. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run-8.
THPC082	Wire Excitation Experiments in the CERN SPS	3176
	U. Dorda, J.-P. Koutchouk, R. Tomas, J. Wenninger, F. Zimmermann CERN, Geneva R. Calaga, W. Fischer BNL, Upton, Long Island, New York
	In order to study the effect of long range interaction and its wire compensation experimentally, current carrying wires are installed in the CERN Super Proton Synchrotron (SPS). In this paper we summarize the main results of the 2007 wire excitation results at 26, 37 and 55 GeV including wire-current-, beam-wire distance and chromaticity scans. A strong dependence on the chromaticity and indications of a threshold effect at 37 and 55 GeV was found. The results are compared to simulation, to a simple analytic scaling law and to experimental results from RHIC. Wire-driven resonances have been observed through the Fourier spectrum of experimental BPM data and compared to simulations.