EPAC 2006 - List of Keywords

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luminosity

Paper	Title	Other Keywords	Page
MOYBPA01	LHC Progress and Commissioning Plans	LHC, injection, dipole, quadrupole	14
	O.S. Brüning CERN, Geneva
	The LHC at CERN is in its final installation phase, and the first tests with beam are planned for part of the machine for the end of 2006. The commissioning of the full machine with beam is planned for summer 2007. The talk summarizes the current status of the LHC installation and the strategy for obtaining an optimum hardware configuration. In a second part the talk outlines the main milestones for the hardware and beam commissioning and presents estimates for the expected performance levels for the commissioning phase with beam.
	Transparencies

MOYBPA02	Operation of High-luminosity Meson Factories and the Challenge to go to the Next Generation	factory, KEKB, feedback, electron	19
	K. Akai KEK, Ibaraki
	This talk will present an overview of the operational status of B- and Phi-Factories, and address their present luminosity performance and limitations, such as electron cloud effects. It will also discuss upgrade plans, including motivation and beam dynamics challenges, new ideas, R&D and machine experiments in view of the next generation of meson factories with ~100 times more luminosity. In particular, it will address machine tests with strong RF focusing, crab cavity developments and first operational experience at KEKB.
	Transparencies

MOPCH098	LHC@FNAL: A Remote Access Center for the LHC at Fermilab	LHC, CERN, monitoring, controls	267
	E.S. McCrory, K.B. Biery, E.G. Gottschalk, S.G. Gysin, E.R. Harms, S.K. Kunori, M.J. Lamm, K.M. Maeshima, P.M. McBride, A.J. Slaughter, A.D. Thomas Fermilab, Batavia, Illinois M. Lamont CERN, Geneva
	A facility is being designed at Fermilab to help people contribute to the Large Hadron Collider (LHC) effort at CERN. This facility is called LHC@FNAL. The purpose of LHC@FNAL is to permit members of the LHC community in North America contribute their expertise to LHC activities at CERN, and to assist CERN with the commissioning and operation of the LHC accelerator and CMS experiment. As a facility, LHC@FNAL has three primary functions: 1) To provide access to information in a manner that is similar to what is available in control rooms at CERN, and to enable members of the LHC community to participate remotely in LHC and CMS activities. 2) To serve as a (bidirectional) communications conduit between CERN and members of the LHC community located in North America. 3. To allow visitors to Fermilab to see firsthand how research is progressing at the LHC. Visitors will be able to see current LHC activities, and will be able to see how future international projects in particle physics can benefit from active participation in projects at remote locations. LHC@FNAL is expected to contribute to a wide range of activities for the CMS experiment and for the LHC accelerator.

MOPCH159	Coupler Design Considerations for the ILC Crab Cavity	coupling, dipole, higher-order-mode, damping	430
	P. Goudket, C.D. Beard CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Burt Microwave Research Group, Lancaster University, Lancaster
	Transverse deflecting cavities, such as the ILC crab cavity, commonly operate in the TM110 dipole mode. This means that in addition to the higher order modes (HOMs), that need to be controlled for every cavity, the fundamental TM010 mode and the other polarisation of the dipole mode also need to be damped. As the resonant frequency of the fundamental mode is much lower than the cut-off frequency of the beampipe, this mode becomes trapped in the cavity and difficult to extract using conventional HOM couplers, hence a dedicated coupler is likely to be required. The ILC crab cavities will require excellent damping of all undesirable modes in order to maintain maximum luminosity at the IP.

MOPCH163	Analysis of Wakefields in the ILC Crab Cavity	dipole, quadrupole, TESLA, simulation	442
	G. Burt, A.C. Dexter Microwave Research Group, Lancaster University, Lancaster C.D. Beard, P. Goudket CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire L. Bellantoni Fermilab, Batavia, Illinois R.M. Jones UMAN, Manchester
	The large crossing angle schemes of the ILC need a correction of bunch orientation at the IP in order to recover a luminosity loss of up to 80%. The orientation of bunches can be changed using a transverse deflecting cavity. The location of the crab cavity would be close to the final focus, and small deflections caused by wakefields in the cavities could cause misalignments of the bunches at the IP. Wakefields in the FNAL CKM cavities have been analysed and their effects studied in view of use as the ILC crab cavity. Numerical simulations have been performed to analyse the transverse wakepotentials of up to quadrupole order modes in this cavity and the effect upon bunches passing through this cavity. Trapped modes within the CKM cavity have been investigated. Perturbation tests of normal conducting models of this cavity have been launched to verify these results. The effect of the final focus quadrupole magnets on the deflection given to the bunch have also been calculated and used to calculate luminosity loss due to wakefields.

MOPLS010	Measurement of Ion Beam Losses Due to Bound-free Pair Production in RHIC	ion, RHIC, LHC, simulation	553
	J.M. Jowett, S.S. Gilardoni CERN, Geneva R. Bruce MAX-lab, Lund K.A. Drees, W. Fischer, S. Tepikian BNL, Upton, Long Island, New York S.R. Klein LBNL, Berkeley, California
	When the LHC operates as a Pb⁸²⁺ ion collider, losses of Pb⁸¹⁺ ions, created through Bound-free Pair Production (BFPP) at the collision point, and localized in cold magnets, are expected to be a major luminosity limit. With Au⁷⁹⁺ ions at RHIC, this effect is not a limitation because the Au⁷⁸⁺ production rate is low, and the Au⁷⁸⁺ beam produced is inside the momentum aperture. When RHIC collided Cu²⁹⁺ ions, secondary beam production rates were lower still but the Cu²⁸⁺ ions produced were predicted to be lost at a well-defined location, creating the opportunity for the first direct observation of BFPP effects in an ion collider. We report on measurements of localized beam losses due to BFPP with copper beams in RHIC and comparisons to predictions from tracking and Monte Carlo simulation.

MOPLS011	Investigations of the Parameter Space for the LHC Luminosity Upgrade	LHC, quadrupole, insertion, separation-scheme	556
	J.-P. Koutchouk CERN, Geneva
	Increasing the LHC luminosity by a factor of ten is a major challenge, not so much for the beam optics but certainly for the beam-beam long-range interactions and even more for the technology and layout: the quadrupole gradient, its physical aperture and tolerance to the energy deposition shall be significantly increased; its distance to the crossing point shall be reduced if the particle detectors can allow it. To help identifying consistent solutions in this multi-dimensional constrained space, a algorithmic model of an LHC insertion was prepared, based on the present LHC layout, i.e., "quadrupole first" and small crossing angle. The model deals with the layout, the beam optics, the beam-beam effect, the superconductor field margins and the peak heat deposition in the coils. The approach is simplified to allow a large gain in the design/computation time for optimization. First results have shown the need to use the Nb3Sn technology (or a material of equivalent performance) to reach the performance goal. In this paper, the model is refined to take into account the quench levels and temperature margins. The optimal insertions within the framework of this approach are identified.

MOPLS016	LHC IR Upgrade: A Dipole First Option with Local Chromaticity Correction	LHC, sextupole, dipole, dynamic-aperture	571
	R. de Maria, O.S. Brüning CERN, Geneva P. Raimondi INFN/LNF, Frascati (Roma)
	In the framework of the LHC Luminosity Upgrade, we develop a new layout of the interaction region (IR) with betastar equal to 25cm in which the combination-separation dipoles come first with respect to the triplet assembly (dipole first) in opposition of the nominal layout (quadrupole first). The new layout presents several advantages (separate channel for multipole errors, straightforward crossing angle scheme, early separation of the beam). The payoff is a large beta function in the triplet, which enhances the chromaticity and other non-linear effects. We investigate options for local chromaticity correction and their effects on long-term stability.

MOPLS017	A Low Gradient Triplet Quadrupole Layout Compatible with NbTi Magnet Technology and Betastar=0.25m	LHC, sextupole, quadrupole, CERN	574
	R. de Maria, O.S. Brüning CERN, Geneva
	The paper presents a triplet layout option with long (ca. 100 m total triplet length), low gradient (45 T/m to 70 T/m) quadrupole magnets. Assuming a maximum magnet diameter of 200mm, the peak coil field at the magnet coils still remains below 7 T which is still compatible with conventional NbTi magnet technology. The peak beta function inside the triplet magnets reaches 18 km and the configuration therefore requires an additional chromaticity correction scheme similar to a dipole first layout option. However, at the same time, the presented solution provides an interesting alternative to a high gradient triplet layout which requires the new Nb3Ti magnet technology.

MOPLS020	Rad-hard Luminosity Monitoring for the LHC	LHC, radiation, CERN, controls	580
	A. Ratti, J.-F. Beche, J.M. Byrd, K. Chow, S. De Santis, P. Denes, B. Ghiorso, H.S. Matis, M. T. Monroy, W.C. Turner LBNL, Berkeley, California E. Bravin CERN, Geneva P.F. Manfredi Pavia University, Engineering faculty, Pavia W. Vandelli Pavia University, Pavia
	Luminosity measurements at the high luminosity points of the LHC are very challenging due to the extremely high radiation levels in excess of 1 GGy/yr. We have designed an ionization chamber that uses a flowing gas mixture and a combination of metals and ceramics. With such a choice, an additonal challenge is achieving the necessary speed to be able to resolve bunch-by-bunch luminosity data. We present the design, analysis and experimental results of the early demonstration tests of this device.

MOPLS024	RHIC Performance as Polarized Proton Collider in Run-6	polarization, RHIC, emittance, AGS	592
	V. Ptitsyn, L. Ahrens, M. Bai, D.S. Barton, J. Beebe-Wang, M. Blaskiewicz, A. Bravar, J.M. Brennan, K.A. Brown, D. Bruno, G. Bunce, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, A.V. Fedotov, W. Fischer, G. Ganetis, H. Hahn, T. Hayes, H.-C. Hseuh, H. Huang, P. Ingrassia, D. 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, C. Montag, J. Morris, T. Nicoletti, B. Oerter, F.C. Pilat, P.H. Pile, T. Roser, T. Russo, J. Sandberg, T. Satogata, C. Schultheiss, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York
	The Relativistic Heavy Ion Collider in Run-6 was operating in polarized proton mode. With two Siberian Snakes per ring, the polarized protons were brought into collisions at 100 Gev and 31.2 Gev energies. The control of polarization orientation at STAR and PHENIX experiments was done using helical spin rotators. Physics studies were conducted with longitudinal, vertical and radial beam polarization at collision points. This paper presents the performance of RHIC as a polarized proton collider in the Run-6 with emphasis on beam polarization and luminosity issues.

MOPLS025	Experience in Reducing Electron Cloud and Dynamic Pressure Rise in Warm and Cold Regions in RHIC	emittance, electron, proton, RHIC	595
	S.Y. Zhang, L. Ahrens, J.G. Alessi, M. Bai, M. Blaskiewicz, P. Cameron, R. Connolly, K.A. Drees, W. Fischer, J. Gullotta, P. He, H.-C. Hseuh, H. Huang, R.C. Lee, V. Litvinenko, W.W. MacKay, C. Montag, T. Nicoletti, B. Oerter, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, L. Smart, L. Snydstrup, S. Tepikian, P. Thieberger, D. Trbojevic, J. Wei, K. Zeno BNL, Upton, Long Island, New York
	Significant improvement has been achieved for reducing electron cloud and dynamic pressure rise at RHIC over several years; however, there remain to be factors limiting luminosity. The large scale application of non-evaporable getter (NEG) coating in RHIC has been proven effective in reducing electron multipacting and dynamic pressure rise. This will be reported together with the study of the saturated NEG coatings. Since beams with increased intensity and shorter bunch spacing became possible in operation, the electron cloud effects on beam, such as the emittance growth,are an increasing concern. Observations and studies are reported. We also report the study results relevant to the RHIC electron cloud and pressure rise improvement, such as the effect of anti-grazing ridges on electron cloud in warm sections, and the effect of pre-pumping in cryogenic regions.

MOPLS026	Monitoring of Interaction-point Parameters using the 3-dimensional Luminosity Distribution Measured at PEP-II	lattice, monitoring, coupling, SLAC	598
	B.F. Viaud Montreal University, Montreal, Quebec W. Kozanecki CEA, Gif-sur-Yvette C. O'Grady, J.M. Thompson, M. Weaver SLAC, Menlo Park, California
	The 3-D luminosity distribution at the IP of the SLAC B-Factory is monitored using e⁺ e^- -> e⁺ e-, mu+ mu- events reconstructed online in the BaBar detector. The transverse centroid and spatial orientation of the luminosity ellipsoid provide a reliable monitor of IP orbit drifts. The longitudinal centroid is sensitive to small variations in the average relative RF phase of the beams and provides a detailed measurement of the phase transient along the bunch train. Relative variations in horizontal luminous size are detectable at the micron level. The longitudinal luminosity distribution depends on the e± overlap bunch length and the vertical IP beta-function betay. In addition to continuous online monitoring of all the IP parameters above, we performed detailed studies of their variation along the bunch train to investigate a temporary luminosity degradation. We also used controlled variations in RF voltage and beam current to extract separate measurements of the e⁺ and e^- bunch lengths. The time-history of the betay measurements, collected over a year of routine high-luminosity operation, are compared with HER & LER phase-advance data periodically recorded in single-bunch mode.

MOPLS027	Beam-beam Simulations for a Single Pass SuperB-factory	emittance, linac, simulation, damping	601
	M.E. Biagini INFN/LNF, Frascati (Roma) P. Raimondi, J. Seeman SLAC, Menlo Park, California D. Schulte CERN, Geneva
	A study of beam-beam collisions for an asymmetric single pass SuperB-Factory is presented. In this scheme an electron and a positron beam are first stored and damped in two damping rings, then extracted, compressed and focused to the IP. After collision the two beams are re-injected in the DR to be damped and extracted for collision again. The explored beam parameters are similar to those used in the design of the International Linear Collider, except for the beam energies. Very flat beams and round beams were compared in the simulations, with the GuineaPig code, in order to optimize both luminosity performances and beam blow-up after collision. With such approach, luminosities of the order of 10³⁶ /(cm² sec) can be achieved. http://arxiv.org/abs/physics/0512235.**D. Schulte. “Study of electromagnetic and hadronic background in the Interaction Region of the TESLA Collider”, PhD Thesis, Hamburg, 1996.

MOPLS028	DAFNE Status Report	injection, collider, feedback, interaction-region	604
	A. Gallo, D. Alesini, M.E. Biagini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, E. Di Pasquale, G. Di Pirro, A. Drago, A. Ghigo, S. Guiducci, M. Incurvati, P. Iorio, C. Ligi, F. Marcellini, C. Marchetti, G. Mazzitelli, C. Milardi, L. Pellegrino, M.A. Preger, L. Quintieri, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Vescovi, M. Zobov INFN/LNF, Frascati (Roma) G. Benedetti CELLS, Bellaterra (Cerdanyola del Vallès) L. Falbo INFN-Pisa, Pisa J.D. Fox, P. Raimondi, D. Teytelman SLAC, Menlo Park, California E. Levichev, S.A. Nikitin, P.A. Piminov, D.N. Shatilov BINP SB RAS, Novosibirsk
	The operation of DAFNE, the 1.02 GeV c.m. e⁺e^- collider of the Frascati National Laboratory with the KLOE detector, started in April 2004 has been concluded at the end of March 2006 with a total delivered luminosity of 2 fb-1 on the peak of the Phi resonance, 0.2 fb-1 off peak and a high statistics scan of the resonance. The best performances of the collider during this run have been a peak luminosity of 1.5 1032 cm-2s-1 and a daily delivered luminosity of 10 pb-1. The KLOE detector has been removed from one of the two interaction regions and its low beta section substituted with a standard magnetic structure, allowing for an easy vertical separation of the beams, while the FINUDA detector has been moved onto the second interaction point. Several improvements on the rings have also been implemented and are described together with the results of machine studies aimed at improving the collider efficiency and testing new operating conditions.

MOPLS029	Preliminary Study of a Crab Crossing System for DAFNE	coupling, betatron, damping, simulation	607
	A. Gallo, D. Alesini, F. Marcellini, P. Raimondi, M. Zobov INFN/LNF, Frascati (Roma)
	The implementation of a crab crossing scheme at the Frascati Phi-factory DAFNE is under consideration, together with several other ideas and upgrades to increase the collider luminosity. The crab crossing is beneficial to the luminosity because it is expected to optimize the geometrical superposition of the colliding bunches and to weaken the synchro-betatron beam-beam resonances. The basic specifications of such a system, the expected luminosity increase, a preliminary design of the crab cavities and the architecture of the dedicated RF system are presented.

MOPLS030	Recent Progress of KEKB	KEKB, optics, electron, vacuum	610
	Y. Funakoshi KEK, Ibaraki
	We summarize the machine operation of KEKB during the past one year, focusing on progress for this period.

MOPLS032	Beam-beam Limit and the Degree of Freedom	emittance, damping, simulation, KEKB	616
	K. Ohmi, K. Oide KEK, Ibaraki E. Perevedentsev BINP SB RAS, Novosibirsk
	Beam-beam limit is caused by chaotic diffusion due to the strong nonlinear force of beam-beam interaction. Degree of freedom in the colliding system is essential for the diffusion. We discuss the diffusion using several models.

MOPLS033	Beam-beam Limit and Feedback Noise	feedback, damping, radiation, kicker	619
	K. Ohmi, Y. Funakoshi, S. Hiramatsu, K. Oide, M. Tobiyama KEK, Ibaraki
	Beam-beam interaction is strongly nonlinear, therefore particles in the beam experience chaotic motion. A small noise can be enhanced by the chaotic nature, with the result that unexpected emittance growth can be observed. We study the noise of transverse bunch by bunch feedback system and related luminosity degradation. Similar effects caused by crab cavity noise is also discussed.

MOPLS037	Beams Injection System for e⁺e^- Collider VEPP-2000	injection, collider, quadrupole, optics	622
	D.E. Berkaev, V.V. Druzhinin, I. Koop, A.P. Lysenko, F.V. Podgorny, V.P. Prosvetov, P.Yu. Shatunov, Y.M. Shatunov, D.B. Shwartz BINP SB RAS, Novosibirsk
	Electron-positron collider VEPP-2000 is under commissioning at the Budker Institute of Nuclear Physics. The paper presents the injection system of the collider delivering the beam from the booster storage ring BEP with maximum energy 900 MeV. A matching of the beam injection with the storage ring optics is done with respect to a nonlinear kicker field. Features of beam diagnostic and transfer line magnets including pulse septums (100 mksec; 30 kGs) and fast kickers (20 nsec; 70 kV) are described. Results of the magnetic measurements and their comparison to calculated data are given.

MOPLS041	MAD-X/PTC Lattice Design for DAFNE at Frascati	survey, collider, emittance, lattice	631
	F. Schmidt CERN, Geneva E. Forest KEK, Ibaraki C. Milardi INFN/LNF, Frascati (Roma)
	In absence of a program that takes as an input the desired or known location of the magnets in the tunnel, accelerator designers have been using MAD8/X that looks at a ring as a sequence of magnets without a connection to the tunnel. In many simple examples that is just fine, but once more complicated structures are treated one is bound to play tricks with MAD. Here PTC comes to the rescue. It is shown how pieces of this machine that exist in MAD-X format are used in PTC to create this double ring, as found in the tunnel, with a proper survey in the forward and backward direction. Special elements have been implemented in MAD-X to allow the full PTC description of the machine. It is discussed how this real PTC model differs from the 'fake' MAD-X model and how well PTC describes the real machine.

MOPLS042	Longitudinal Beam Stability for CESR-c	feedback, positron, synchrotron, storage-ring	634
	R. Holtzapple, J.S. Kern, P.J.S. Stonaha Alfred University, Alfred, New York B. Cerio Colgate University, Hamilton, New York M.A. Palmer Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
	The Cornell Electron-Positron Storage Ring (CESR) operates at 1.9 GeV per beam for high energy physics collisions. To maintain high luminosity it is essential for the bunch trains to be longitudinally stable. Measurements of longitudinal stability with a single, multiple, and colliding trains have been performed using a dual sweep streak camera and are presented in this paper.

MOPLS044	Luminosity Variations along Bunch Trains in PEP-II	electron, synchrotron, quadrupole, positron	640
	F.-J. Decker, M. Boyes, W.S. Colocho, A. Novokhatski, M.K. Sullivan, J.L. Turner, S.P. Weathersby, U. Wienands, G. Yocky SLAC, Menlo Park, California
	In spring of 2005 after a long shut-down, the luminosity of the B-Factory PEP-II decreased along the bunch trains by about 25-30%. There were many reasons studied which could have caused this performance degradation, like a bigger phase transient due to an additional RF station in the Low-Energy-Ring (LER), bad initial vacuum, electron cloud, chromaticity, steering, dispersion in cavities, beam optics, etc. The initial specific luminosity of 4.2 sloped down to 3.2 and even 2.8 for a long train (typical: 130 of 144), later in the run with higher currents and shorter trains (65 of 72) the numbers were more like 3.2 down to 2.6. Finally after steering the interaction region for an unrelated reason (overheated BPM buttons) and the consequential lower luminosity for two weeks, the luminosity slope problem was mysteriously gone. Several parameters got changed and there is still some discussion about which one finally fixed the problem. Among others, likely candidates are: the LER betatron function in x at the interaction point got reduced, making the LER x stronger, dispersion reduction in the cavities, and finding and fixing a partially shorted magnet.

MOPLS045	Achieving a Luminosity of 10³⁴/cm²/s in the PEP-II B-factory	injection, electron, positron, beam-beam-effects	643
	J. Seeman, J. Browne, Y. Cai, W.S. Colocho, F.-J. Decker, M.H. Donald, S. Ecklund, R.A. Erickson, A.S. Fisher, J.D. Fox, S.A. Heifets, R.H. Iverson, A. Kulikov, A. Novokhatski, V. Pacak, M.T.F. Pivi, C.H. Rivetta, M.C. Ross, P. Schuh, K.G. Sonnad, M. Stanek, M.K. Sullivan, P. Tenenbaum, D. Teytelman, J.L. Turner, D. Van Winkle, M. Weaver, U. Wienands, W. Wittmer, M. Woodley, Y.T. Yan, G. Yocky SLAC, Menlo Park, California M.E. Biagini INFN/LNF, Frascati (Roma) W. Kozanecki CEA, Gif-sur-Yvette
	For the PEP-II Operation Staff: PEP-II is an asymmetric e⁺e^- collider operating at the Upsilon 4S and has recently set several performance records. The luminosity has exceeded 1x10³⁴/cm²/s and has delivered an integrated luminosity of 728/pb in one day. PEP-II operates in continuous injection mode for both beams, boosting the integrated luminosity. The peak positron current has reached 2.94 A and 1.74 A of electrons in 1732 bunches. The total integrated luminosity since turn on in 1999 has reached over 333/fb. This paper reviews the present performance issues of PEP-II and also the planned increase of luminosity in the near future to over 2 x 10³⁴/cm²/s. Upgrade details and plans are discussed.

MOPLS047	Design of an Asymmetric Super-B Factory	collider, emittance, interaction-region, factory	646
	J. Seeman, Y. Cai, A. Novokhatski, A. Seryi, M.K. Sullivan, U. Wienands SLAC, Menlo Park, California M.E. Biagini, P. Raimondi INFN/LNF, Frascati (Roma)
	Submitted for the High Luminosity Study Group for an Asymmetric Single-pass Super-B Factory: Parameters are being studied for a high luminosity e⁺e^- collider operating at the Upsilon 4S that would deliver a luminosity of over 10³⁶/cm²/s. This collider would use a novel combination of linear collider and storage ring techniques. In this scheme an electron beam and a positron beam are first stored in fast-damping and low-emittance damping rings, then extracted, accelerated, compressed and focused to the interaction point. After collision the two beams are decelerated and re-injected in the damping rings to be damped and extracted for collision again. The explored beam parameters are similar to those used in the design of the International Linear Collider, except for the beam energies. Design parameters for very flat beams and round beams have been studied.

MOPLS048	Doubling the PEP-II Luminosity in Simulations	simulation, damping, emittance, SLAC	649
	Y. Cai, J. Seeman, K.G. Sonnad, U. Wienands SLAC, Menlo Park, California
	The PEP-II luminosity reached 1x10³⁴cm-2s-1 in October 2005. The question of how to increase the luminosity using modest improvements in the PEP-II accelerator in the coming years is the subject of this paper. We found that the parasitic collisions significantly degrade the simulated luminosity as the beam currents are increased from 3A and 1.7A to 4A and 2.2A in the low and high energy rings, respectively. Using the beam-beam code BBI, we systematically optimized the luminosity and showed that a luminosity of over 2x10³⁴cm-2s-1 is achievable within the limits of machine parameters.

MOPLS049	Anomalous High Radiation Beam Aborts in the PEP-II B-factory	vacuum, background, radiation, SLAC	652
	M.K. Sullivan, Y. Cai, S. DeBarger, F.-J. Decker, S. Ecklund, A.S. Fisher, S.M. Gierman, S.A. Heifets, R.H. Iverson, A. Kulikov, N. Kurita, S.J. Metcalfe, A. Novokhatski, J. Seeman, K.G. Sonnad, D. Teytelman, J.L. Turner, U. Wienands, D. Wright, Y.T. Yan, G. Yocky SLAC, Menlo Park, California
	The PEP-II B-factory at SLAC has recently experienced unexpected beam losses due to anomalously high radiation levels at the BaBar detector. The problem was finally traced to the occurrence of very high pressure (>100 nTorr) spikes that have a very short duration (few seconds). We describe the events and show analysis predicting where in the vacuum system the events originated and describe what was discovered in the vacuum system.

MOPLS050	Combined Phase Space Characterization at the PEP-II IP using Single-beam and Luminous-region Measurements	emittance, lattice, coupling, simulation	655
	A.J. Bevan Queen Mary University of London, London Y. Cai, A.S. Fisher, C. O'Grady, J.M. Thompson, M. Weaver SLAC, Menlo Park, California W. Kozanecki CEA, Gif-sur-Yvette B.F. Viaud Montreal University, Montreal, Quebec
	We present a novel method to characterize the e ± phase space at the IP of the SLAC B-factory, that combines single-beam measurements with a detailed mapping of luminous-region observables. Transverse spot sizes are determined in the two rings with synchrotron-light monitors & extrapolated to the IP using measured lattice functions. The 3-D luminosity distribution, as well as the spatial dependence of the transverse-boost distribution of the colliding beams, are measured using e⁺ e^- –> mu+ mu- events reconstructed in the BaBar tracking detectors; they provide information on the luminous spot size, the e^- angular divergence & the vertical emittance. The specific luminosity, which is proportional to the inverse product of the overlap IP beam sizes, is continuously monitored using Bhabha-scattering events. The combination of these measurements provide constraints on the horizontal & vertical spot sizes, angular divergences, emittances & beta functions of both beams at the IP during routine high-luminosity operation. Preliminary results of this combined-spot size analysis are confronted with measurements of IP beta-functions & overlap IP beam sizes at low beam current.

MOPLS052	Luminosity Improvement at PEP-II Based on Optics Model and Beam-beam Simulation	simulation, optics, sextupole, synchrotron	661
	Y. Cai, W.S. Colocho, F.-J. Decker, Y. Nosochkov, P. Raimondi, J. Seeman, K.G. Sonnad, M.K. Sullivan, J.L. Turner, M. Weaver, U. Wienands, W. Wittmer, M. Woodley, Y.T. Yan, G. Yocky SLAC, Menlo Park, California
	The model independent analysis (MIA) has been successfully used at PEP-II to understand machine optics and improve the luminosity. However, the rate of success was limited because the improvement of optics does not necessarily lead to increase of luminosity. Recently, we were able to reconstruct MIA model in a full optics code, LEGO, and used it to calculate complete lattice and beam parameters. These parameters were fed to the beam-beam code, BBI, to understand the luminosity histories at PEP-II over the past year. Using these tools, we optimized the luminosity by varying the beam parameters such as emittance. Finally, we implemented an optimized solution with a set of asymmetric horizontal orbit bumps into the machines during a delivery shift with a few percentage gain in luminosity. The solution was retained at PEP-II machines along with the luminosity. Later, these asymmetric bumps also played a vital role in reaching 1x10³⁴cm-2s-1 as the beam currents increased.

MOPLS053	Beta-beat Correction Using Strong Sextupole Bumps in PEP-II	sextupole, closed-orbit, coupling, SLAC	664
	G. Yocky SLAC, Menlo Park, California
	A method for correcting lattice beta mismatches has been developed for the PEP-II collider using orbit offsets in strong sextupoles. The solution is first predicted in the MAD program by modeling closed orbit bumps in the plane of correction at the sextupoles strongest in that plane. The derived solution is then tested in the machine to confirm the prediction and finally dialed into the machine under high-current conditions.

MOPLS054	On Increasing the HERA Luminosity	proton, lepton, optics, electron	667
	Y.A. Kot, F.J. Willeke DESY, Hamburg
	The luminosity of the HERA lepton proton collider is limited in part by the bunch length of the protons of 20cm. This limitation is expected to be removed by the installation of a new damper system which will control longitudinal coupled bunch instabilities of the proton beam and avoid the bunch lengthening of a factor of two. This opens the possibility for increasing the luminosity HERA since the beta functions at IP for both leptons and protons can be lowered by about 20% without noticeable reduction of the corresponding luminosity by the so-called hour-glass effect. The beam spot size can be further reduced if the beam-beam focusing of the leptons (dynamic beta) at IP is increased by softening the rigorous beam beam-beta beat compensation which is accomplished by proper phasing of the two IP's. Unfortunately the non-linear chromaticity compensation would be weakened as well, which will cause an enhancement of the synchro-betatron resonances and may lead to poor lifetime and poor background conditions. Therefore, the non-linear chromaticity needs to be reduced by means of a more complex scheme of chromaticity compensating sextupole magnets.

MOPLS055	A Lepton-proton Collider with LHC	proton, lepton, LHC, collider	670
	F.J. Willeke DESY, Hamburg J.B. Dainton Cockcroft Institute, Warrington, Cheshire M. Klein DESY Zeuthen, Zeuthen P. Newman Birmingham University, Birmingham E. Perez CEA, Gif-sur-Yvette
	The physics, and a design, of a Large Hadron Electron Collider (LHeC) are sketched. With high luminosity, 10³³cm-2s-1, and high energy, ?s = 1.4TeV, such a collider can be built in which a 70GeV electron (positron) beam in the LHC tunnel is in collision with one of the LHC hadron beams and which operates simultaneously with the LHC. The LHeC makes possible deep-inelastic lepton-hadron (ep, eD and eA) scattering for momentum transfers Q2 beyond 106GeV2 and for Bjorken x down to the 10-6. New sensitivity to the existence of new states of matter, primarily in the lepton-quark sector and in dense partonic systems, is achieved. The precision possible with an electron-hadron experiment brings in addition crucial accuracy in the determination of hadron structure, as described in Quantum Chromodynamics, and of parton dynamics at the TeV energy scale. The LHeC thus complements the proton-proton and ion programmes, adds substantial new discovery potential to them, and is important for a full understanding of physics in the LHC energy range. Contributed to the Open Symposium on European Strategy for Particle Physics Research, LAL Orsay, France, January 30th to February 1st , 2006. hep-ex/0603016 DESY 06-00Cockcroft-06-05

MOPLS058	eRHIC - Future Machine for Experiments on Electron-ion Collisions	electron, proton, ion, positron	676
	V. Ptitsyn, J. Beebe-Wang, I. Ben-Zvi, A.V. Fedotov, W. Fischer, W. Graves, V. Litvinenko, W.W. MacKay, C. Montag, S. Ozaki, T. Roser, S. Tepikian, D. Trbojevic BNL, Upton, Long Island, New York D.P. Barber DESY, Hamburg W.A. Franklin, R. Milner, B. Surrow, C. Tschalaer, E. Tsentalovich, D. Wang, F. Wang, A. Zolfaghari, T. Zwart, J. van der Laan MIT, Middleton, Massachusetts A.V. Otboev, Y.M. Shatunov BINP SB RAS, Novosibirsk
	The paper presents recent developments for the design of the high luminosity electron-ion collider, eRHIC, proposed on the basis of the existing RHIC machine. The goal of eRHIC is to provide collisions of electrons and positrons on ions and protons in the center-of-mass energy range from 30 to 100 GeV. Lepton beams as well as the beam of protons (and, possibly, light ions) should be polarized. Two independent designs are under development, the so-called 'ring-ring' and 'linac-ring' options. The 'ring-ring' option is based on a 10 GeV electron storage ring. The design issues for the 'ring-ring' option are similar to those at existing B-factories. In the 'linac-ring' option, the electron beam is accelerated in a 10 GeV recirculating energy recovery linac. This option may provide higher luminosities (> 1·10³³ cm-2s-1 for e-p collisions), but requires considerable R&D studies for a high current electron polarized source. In order to maximize the collider luminosity, ion ring upgrades, such as electron cooling and ion beam intensity increase, are considered.

MOPLS060	Design of an Interaction Region with Head-on Collisions for the ILC	extraction, optics, quadrupole, dipole	682
	J. Payet, O. Napoly, C. Rippon, D. Uriot CEA, Gif-sur-Yvette M. Alabau Pons, P. Bambade, J. Brossard, O. Dadoun, C. Rimbault LAL, Orsay D.A.-K. Angal-Kalinin, F. Jackson CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire R. Appleby UMAN, Manchester L. Keller, Y. Nosochkov, A. Seryi SLAC, Menlo Park, California
	An interaction region with head-on collisions is considered an alternative to the baseline configuration of the International Linear Collider, including two interaction regions with finite crossing-angles (2 and 20 mrad). Although more challenging from the point of view of the beam extraction, the head-on scheme is favoured by the experiments because it allows a more convenient detector configuration, particularly in the forward region. The optics of the head-on extraction is revisited by separating the e⁺ and e^- beams horizontally, first by electrostatic separators operated at their LEP nominal field and then using a defocusing quadrupole of the final focus beam line. In this way the septum magnet is protected from the beamstrahlung power. Newly optimized final focus and extraction optics are presented, including a first look at post-collision diagnostics. The influence of parasitic collisions is shown to lead to a region of stable collision parameters. Beam and beamstrahlung photon losses are calculated along the extraction elements. Issues concerning the design of the large bore superconducting final focus magnets, common to both incoming and outgoing beams, are considered.

MOPLS061	Optimization of the e-e^- Option for the ILC	extraction, simulation, quadrupole, optics	685
	M. Alabau Pons, M. Alabau Pons, A. Faus-Golfe IFIC, Valencia R. Appleby UMAN, Manchester P. Bambade, O. Dadoun LAL, Orsay
	The e-e^- running mode is one of the interesting physics options for the International Linear Collider. The luminosity for e-e^- collisions is reduced by mutual defocusing due to the strong electromagnetic fields that the bunches experience during collisions. The resulting beamstrahlung energy loss and beam-beam deflection angles as function of the vertical transverse offset are different compared to the e⁺e^- collisions. In this paper, the dependence of these observables with the offset for different beam sizes has been analysed to optimize performances for the e-e^- mode, taking into account the requirements of the beam-beam deflection based intra-train feedback system. A first study of the implications for the final focus and extraction line optics is also presented for the cases of the 2mrad and 20mrad ILC base line crossing angle geometries.

MOPLS075	Progress towards Crab Cavity Solutions for the ILC	focusing, quadrupole, electron, positron	724
	G. Burt, A.C. Dexter Cockcroft Institute, Warrington, Cheshire C.D. Beard, P. Goudket CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire L. Bellantoni Fermilab, Batavia, Illinois
	In order to achieve acceptable luminosity for ILC crossing angles greater than a few mrad, RF deflection cavities must be used to rotate electron and position bunches leading up to the IP. A bunch that passes through a deflection cavity at a phase where the deflection averages to zero receives a crab kick leading to a finite rotation at the IP. For a beam energy of 500GeV and a crossing angle of 20mrad, the required crab kick is about 19.5MV at 1.3GHz and 6.5MV at 3.9GHz. Cavities are needed on both beams and are likely to be positioned about 12m before the IP. Any RF phase error between the bunch and the cavity leads to a deflection of the bunch in addition to a rotation of the bunch. Any differential phase error between the cavities leads to differing deflections and consequential loss in luminosity. Collaborative work with FNAL, being undertaken to develop a variant of their 3.9GHz CKM cavity optimised for an ILC solution, is described. Current analysis favours a solution with four nine-cell cavities on each beam. It is anticipated that the cavities will be run CW and driven from small Klystron/s (< 5kW) or solid state amplifiers.* *We would like to thank Chris Adolphsen, SLAC, for his help in technical discussions, which were greatly appreciated.

MOPLS081	A Study of Laser System Requirements for Application in Beam Diagnostics and Polarimetry at the ILC	laser, diagnostics, controls, optics	741
	S. Dixit, N. Delerue, K.J. Peach JAI, Oxford G.A. Blair, S.T. Boogert, G.E. Boorman, A. Bosco, C. Driouichi Royal Holloway, University of London, Surrey A. Brachmann, J.C. Frisch, M.C. Ross SLAC, Menlo Park, California F.B. Foster, D.F. Howell, Q.G. Quelch, Q.M. Qureshi, A. Reichold OXFORDphysics, Oxford, Oxon G.J. Hirst, I. N. Ross CCLRC/RAL, Chilton, Didcot, Oxon V. Soskov, V. Variola, Z.F. Zomer LAL, Orsay J. Urakawa KEK, Ibaraki
	Advanced laser systems will be essential for a range of diagnostics devices at the ILC. High average power, excellent stability and reliability will be crucial in order to deliver the information required to attain the necessary ILC luminosity. The key parameters are listed together with the R&D required to achieve the necessary laser system performance.

MOPLS092	Efficient Collimation and Machine Protection for the Compact Linear Collider	CLIC, collimation, linac, kicker	768
	R.W. Assmann, F. Zimmermann CERN, Geneva
	We present a new approach to machine protection and collimation in CLIC, separating these two functions: If emergency dumps in the linac protect the downstream beam line against drive-beam failures, the energy collimation only needs to clean the beam tails and can be compact. Overall, the length of the beam delivery system is significantly reduced.

MOPLS094	Luminosity Tuning at the Interaction Point	sextupole, simulation, linac, quadrupole	774
	P. Eliasson, M. Korostelev, D. Schulte, R. Tomas, F. Zimmermann CERN, Geneva
	Minimisation of the emittance in a linear collider is not enough to achieve optimal performance. For optimisation of the luminosity, tuning of collision parameters such as angle, offset, waist, etc. is needed, and a fast and reliable tuning signal is required. In this paper tuning knobs are presented, and their optimisation using beamstrahlung as a tuning signal is studied.

MOPLS096	Effects of Wake Fields in the CLIC BDS	CLIC, quadrupole, emittance, betatron	780
	G. Rumolo, A. Latina, D. Schulte CERN, Geneva
	The wake fields due to collimators in the Beam Delivery System of CLIC are modeled using a conventional approach. According to the chosen ranges of parameters, differences in the transverse kicks due to both the geometric and resistive wall components for different regimes are highlighted (inductive or diffractive for the geometric wake fields, short- or long-range, ac or dc for the resistive wall wake fields). A module for particle tracking along the BDS including the effect of wake fields has been introduced in PLACET, and the first tracking results are shown.

MOPLS100	CLIC Final Focus Studies	CLIC, octupole, sextupole, quadrupole	792
	R. Tomas, H.-H. Braun, D. Schulte, F. Zimmermann CERN, Geneva
	The design of the CLIC final focus system is based on the local compensation scheme proposed by P. Raimondi and A. Seryi. However, there exist important chromatic aberrations that deteriorate the performance of the system. This paper studies the optimization of the final focus based on the computation of the high orders of these aberrations using MAD-X and PTC. The use of octupole doublets to reduce the size of the halo in the locations with aperture limitations is also discussed.

MOPLS117	Tuning Algorithms for the ILC Beam Delivery System	sextupole, coupling, emittance, quadrupole	837
	J.K. Jones CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	Emittance preservation is an important aspect in the design and running of the International Linear Collider (ILC) with a direct consequence on the luminosity of the machine. The Beam Delivery System represents a major problem in this respect as it produces emittance dilution effects that are difficult to correct and that have a direct effect on the emittance as seen at the interaction point, and thus upon the luminosity of the machine. Tuning algorithms for this section of the machine rely on the correction of aberrations through the use of linear and higher order knobs, using corrections magnets distributed throughout the system. Alternative systems are also discussed. The design and implementation of these tuning algorithms, and their effectiveness in a variety of cases, are investigated and estimates made for tolerances on a variety of error sources. Simulations results are also presented for models of the ATF-2 accelerator under development at KEK, with comparisons made to the ILC design.

TUXPA02	RHIC Operational Status and Upgrade Plans	RHIC, ion, electron, proton	905
	W. Fischer BNL, Upton, Long Island, New York
	Since 2000 RHIC has collided, at 8 energies, 4 combinations of ion species, ranging from gold ions to polarized protons, and including the collisions of deuterons with gold ions. During that time the heavy ion luminosity increased by 2 orders of magnitude, and the proton polarization in store reached 46% on average. Planned upgrades include the evolution to the Enhanced Design parameters by 2008, the construction of an Electron Beam Ion Source (EBIS) by 2009, the installation of electron cooling for RHIC II, and the implementation of the electron-ion collider eRHIC. We review the expected operational performance with these upgrades.
	Transparencies

TUXPA03	LHC Luminosity and Energy Upgrades	LHC, dipole, SPS, injection	910
	W. Scandale CERN, Geneva
	LHC upgrade studies are ongoing as part of the EU CARE-HHH network and in the US-LARP collaboration. The aim is a ten-fold increase of the LHC luminosity by about 2014 and a possible upgrade of the injector complex to inject at 1 TeV and, at a later stage, to raise the collider energy. This talk will provide an overview of the beam dynamics and technological challenges associated with the LHC upgrade, including magnet R&D plans, electron cloud and beam-beam limitations, preferred scenarios to maximize the integrated luminosity, and machine experiments on beam-beam compensation or crystal collimation.
	Transparencies

TUZBPA01	The ERL High Energy Cooler for RHIC	electron, RHIC, ERL, emittance	940
	I. Ben-Zvi BNL, Upton, Long Island, New York
	This talk will first briefly review high-energy electron cooling, including the recent results from Fermilab. The main empasis will be on describing the proposed electron-cooling device for RHIC, based on an Energy Recovery Linac. Finally, results from the prototype ERL will presented.
	Transparencies

TUODFI02	DAFNE Experience with Negative Momentum Compaction	electron, positron, lattice, feedback	989
	M. Zobov, D. Alesini, M.E. Biagini, A. Drago, A. Gallo, C. Milardi, P. Raimondi, B. Spataro, A. Stella INFN/LNF, Frascati (Roma)
	There are several potential advantages for a collider operation with a lattice having a negative momentum compaction factor (alfa): bunches can be shorter and have a more regular shape; longitudinal beam-beam effects and synchrobetatron resonances are predicted to be less dangerous; requirements on sextupole strengths can be relaxed because there is no head-tail instability with the negative chromaticity. Since the lattice of the Frascati e⁺e^- Phi-factory DAFNE is flexible enough to provide collider operation with alfa < 0, we have exploited this possibility to study experimentally the beam dynamics. The negative momentum compaction lattices have been successfully implemented and stable 1 A currents have been stored in both the electron and positron rings without any problem for RF cavities and feedback systems operation. First collisions have been tested at low currents. In this paper we describe the experimental results and compare them with expectations and numerical simulations. Present limitations to DAFNE operation with alfa < 0 are also discussed.
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TUODFI03	Operational Status of CESR-c	optics, wiggler, electron, positron	992
	J.A. Crittenden Cornell University, Department of Physics, Ithaca, New York
	We summarize recent running experience at the Cornell Electron Storage Ring operating as a high-statistics production-threshold factory for mesons containing charm quarks. Since beginning operation at beam energies near 2 GeV in late 2003, CESR has accumulated world-record samples of D and D$_s$ meson decays and has also operated in an energy-scanning mode, making unique contributions to the presently very active field of charm spectroscopy. CESR lattice design is characterized by the versatility provided by the variety of beam-line components applied to the challenges imposed by the beam-beam interactions at the parasitic crossing points in the pretzel orbits and the necessity of powerful superconducting wiggler magnets used to tune damping and emittance. We describe the observed tune-plane, beam-current and luminosity limits, as well as our understanding of their sources and near-term plans for operational improvements.
	Transparencies

TUPCH023	Direct Observation of Beam-beam Induced Dynamical Beta Beating at HERA	electron, proton, synchrotron, synchrotron-radiation	1046
	G. Kube, F.J. Willeke DESY, Hamburg
	The Hadron Electron Ring Anlage (HERA) at DESY provides collisions between a 920 GeV proton beam and a 27.5 GeV electron beam in two interaction regions. The strong beam-beam force, which mainly affects the electrons, induces a tune shift together with a dynamical beta beat. The latter leads to a modification of the transverse beam profile, which can be observed in different profile monitors in HERA. The time-like evolution of the electron beam shape during luminosity tuning and before and after dump of the proton beam, averaged over all bunches, could be studied by means of a synchrotron radiation profile monitor. Measurements with a wire scanner allowed to see the beam-beam force's influence on each individual bunch at the expense of resolution. The observations could be explained qualitatively in the frame of linear incoherent beam-beam interaction.

TUPCH056	A Simpler Method for SR Interferometer Calibration	extraction, KEKB, closed-orbit, synchrotron	1136
	J.W. Flanagan, H. Fukuma, S. Hiramatsu, H. Ikeda, T. Mitsuhashi KEK, Ibaraki
	Previous methods of performing absolute calibration of the SR interferometer used at KEKB (measuring mirror distortion with a pinhole mask, virtual beam broadening via local bumps, physical beam broadening via dispersion bumps) are very time-consuming, and require dedicated machine time to take the necessary data. We report on a new, simpler method we have developed, wherein we create small local bumps at the SR source point and observe the resulting shifts in the phase of the interference fringes. From these data we can calibrate the total magnification of the system, including the effects of mirror distortion. The calibration data can be taken in a very small amount of time (tens of minutes), and in parallel with physics running, without stopping the beam-size measurement system or interfering with its use for luminosity tuning. By taking the calibration data at different beam currents and correlating the magnification at each current with the appropriate interference pattern fit parameters, we can also obtain the parameters needed for real-time mirror distortion correction.

WEYPA01	Beam Delivery System in ILC	linac, quadrupole, electron, feedback	1852
	G.A. Blair Royal Holloway, University of London, Surrey
	The presentation will review the challenges of this key ILC sub-system in terms of beam performances, machine protection system, collimation, interaction with the detector and compare them with the achievements in SLC and FFTB. It will then present the world-wide organization to define and make the necessary R&D for the design, beam simulations and benchmarking in tests facilities, especially the ATF2 facility under construction at KEK. It will explore the major issues both from the beam dynamics and the technological point of view, as well as the plans foreseen and the schedule to address them. It will finally analyze the possible upgrade in energy together with the possible limitations and associated issues.
	Transparencies

WEOAPA02	Optimum Frequency and Gradient for the CLIC Main Linac	linac, CLIC, emittance, damping	1867
	A. Grudiev, D. Schulte, W. Wuensch CERN, Geneva
	A novel procedure for the optimization of the operating frequency, the accelerating gradient, and many other parameters of the CLIC main linac is presented. Based on the new accelerating structure design HDS (Hybrid Damped Structure), the optimization procedure takes into account both beam dynamics (BD) and RF constraints. BD constraints are related to emittance growth due to short- and long-range transverse wakefields. RF constraints are related to RF breakdown and pulsed surface heating limitations of the accelerating structure. Interpolation of beam and structure parameters in a wide range allows hundreds of millions of structures to be analyzed. Only those structures which satisfy BD and RF constraints are evaluated further in terms of ratio of luminosity to main linac input power, which is used as the figure of merit. The frequency and gradient have been varied in the range 12-30 GHz and 90-150 MV/m, respectively. It is shown that the optimum frequency varies in the range from 16 to 20 GHz depending on the accelerating gradient and that the optimum gradient is below 100 MV/m and that changing frequency and gradient can double the luminosity for the same main linac input power.
	Transparencies

WEPCH044	Interaction Region with Slim Quadrupoles	quadrupole, LHC, interaction-region, beam-beam-effects	2014
	E. Laface, R. Ostojic, W. Scandale, D. Tommasini CERN, Geneva C. Santoni Université Blaise Pascal, Clermont-Ferrand
	An optical performance's improvement of the interaction region can be obtained with the addition of new quadrupoles in the forward detectors area. Such scenario would allow decreasing the $β*$ below the nominal value. The basic concept consists in using quadrupoles to break the quadratic behavior of $β$ in the free space between the IP and the IR triplets. In this new configuration we present the performance improvements and the hardware requirements.

WEPCH058	Progress with Collision Optics of the Fermilab Tevatron Collider	optics, quadrupole, resonance, lattice	2053
	A. Valishev, Y. Alexahin, G. Annala, V.A. Lebedev, V.P. Nagaslaev Fermilab, Batavia, Illinois V. Sajaev ANL, Argonne, Illinois
	Recent advances in the measurement and modeling of the machine parameters and lattice functions at the Tevatron allowed modifications of the collision optics to be performed in order to increase the collider luminosity. As the result, beta functions in the two collision points were decreased from 35cm to 29cm which resulted in ~10% increase of the peak luminosity. In this report we describe the results of optics measurements and corrections. We also discuss planned improvements, including the new betatron tune working point and correction of the beta function chromaticity.

WEPCH094	An Early Beam Separation Scheme for the LHC	LHC, separation-scheme, dipole, beam-beam-effects	2134
	J.-P. Koutchouk, G. Sterbini CERN, Geneva
	The high nominal luminosity of the LHC requires a large number of bunches spaced by about 7.5 m. To prevent more than one head-on collision in each interaction region, a crossing angle of 0.285 mrad is necessary. A side effect of this crossing angle is the increase of the effective transverse beam cross-section, thereby decreasing the luminosity by some 16%. For the LHC upgrade, depending on the focusing scenarios, this loss significantly increases and largely offsets the potential gain of a stronger focusing. In this paper we analyze a strategy to circumvent this difficulty, based an early beam separation using small dipoles placed at a few meters from the interaction point, deep inside the detectors. This allows quasi co-linear head-on collisions at the crossing point only. From the beam dynamics point of view, the essential constraint is to control the long-range beam-beam interactions in a scenario where the normalized beam separation is not constant. In this paper the criteria of the analysis and the performance improvement obtained with the scheme are discussed. The strength of the dipoles is estimated as well as the impact on the detectors structure.

WEPCH119	Beam Performance with Internal Targets in the High-energy Storage Ring (HESR)	target, beam-losses, antiproton, scattering	2197
	A. Lehrach, R. Maier, D. Prasuhn FZJ, Jülich O. Boine-Frankenheim, R.W. Hasse GSI, Darmstadt F. Hinterberger Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn
	The High-energy Storage Ring of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton synchrotron storage ring in the momentum range of 1.5 to 15 GeV/c. An important feature of HESR is the combination of phase space cooled beams and dense internal targets (e.g., pellet targets), which results in demanding beam parameter requirements for two operation modes: high luminosity mode with peak luminosities of up to 2·10³² cm-2 s-1, and high resolution mode with a momentum spread down to 10-5, respectively. The beam cooling equilibrium and beam loss with internal target interaction is analyzed. Rate equations are used to predict the rms equilibrium beam parameters. The cooling and intra-beam scattering rate coefficients are obtained from simplified models. Energy loss straggling in the target and the associated beam loss are analyzed analytically assuming a thin target. A longitudinal kinetic simulation code is used to study the evolution of the momentum distribution in coasting and bunched beam. The analytic expressions for the target induced momentum tail are found in good agreement with the simulation results. *A. Lehrach et al. Beam Performance and Luminosity Limitations in the High-Energy Storage Ring (HESR), Nuclear Inst. and Methods in Physics Research, A44704 (2006).

WEPCH138	Simulations of Long-range Beam-beam Interaction and Wire Compensation with BBTRACK	simulation, LHC, RHIC, emittance	2245
	U. Dorda, F. Zimmermann CERN, Geneva
	We present weak-strong simulation results for the effect of long-range beam-beam collisions in LHC, SPS, RHIC and DAFNE, as well as for proposed wire compensation schemes or wire experiments, respectively. In particular, we discuss details of the simulation model, instability indicators, the effectiveness of compensation, the difference between nominal and PACMAN bunches for the LHC, beam experiments, and wire tolerances. The simulations are performed with the new code BBTRACK.

WEPCH140	Recent Improvements of PLACET	CLIC, linac, simulation, ground-motion	2251
	A. Latina, H. Burkhardt, L. Neukermans, G. Rumolo, D. Schulte, R. Tomas CERN, Geneva P. Eliasson Uppsala University, Uppsala J. Resta-López IFIC, Valencia
	The tracking code PLACET is used to simulate the beam transport in linear colliders from the damping ring to the interaction point and beyond. Recent improvements of the code are presented. They include the possibility to simulate bunch compressors and to use parallel computer systems.

WEPLS009	Summary of the Low Emittance Muon Collider Workshop (February 6-10, 2006)	collider, emittance, proton, target	2412
	R.P. Johnson, K. Paul Muons, Inc, Batavia V. Yarba Fermilab, Batavia, Illinois
	The Low Emittance Muon Collider workshop, held at Fermilab February 6-10, 2006 focused on the development of high-luminosity muon colliders using extreme muon beam cooling, where many constraints on muon collider designs are alleviated with beams of smaller emittance and lower intensity. The workshop covered topics related to proton drivers, targetry, muon capture, bunching, cooling, cooling demonstration experiments, bunch recombination, muon acceleration, collider lattices, interaction-point design, site boundary radiation, and detector concepts for energy frontier and Higgs particle studies. Lower emittance allows for a reduction in the required muon current for a given luminosity and also allows high energy to be attained by recirculating the beam through high frequency ILC RF cavities. The highlights of the workshop and the prospects for such colliders will be discussed.

WEPLS108	High Field Solenoid Magnets for Muon Cooling	TESLA, collider, emittance, scattering	2634
	S.A. Kahn, M. Alsharo'a, P.M. Hanlet, R.P. Johnson, M. Kuchnir, D.J. Newsham Muons, Inc, Batavia R.C. Gupta, R. Palmer, E. Willen BNL, Upton, Long Island, New York
	Magnets made with high-temperature superconducting (HTS) coils operating at low temperatures have the potential to produce extremely high fields for use in beam lines and accelerators. The specific application of interest that we are proposing is to use a very high field (of the order of 50 Tesla) solenoid to provide a very small beta region for the final stages of cooling for a muon collider. With the commercial availability of HTS tape based on BSCCO technology with high current carrying capacity at 4.2 K, very high field solenoid magnets should be possible. In this paper we will evaluate the technical issues associated with building this magnet. In particular we will address how to mitigate the high Lorentz stresses associated with this high field magnet.

WEPLS112	Study of 2-in-1 Large-aperture Nb3Sn IR Quadrupoles for the LHC Luminosity Upgrade	quadrupole, LHC, dynamic-aperture, magnet-design	2643
	A.V. Zlobin, V. Kashikhin Fermilab, Batavia, Illinois
	After LHC operates for several years at nominal parameters, it will be necessary to upgrade it to higher luminosity. Replacement of the low-beta insertions with higher performance design based on advanced superconducting magnets is one of the most straightforward steps in this direction. An interesting option for a new IR design is a double bore inner triplet with separation dipoles placed in front of the focusing quadrupoles. This approach reduces the number of parasitic collisions by more than a factor of three with respect to the quadrupoles-first option and allows independent field error correction for each beam. Several designs of the 2-in-1 Nb3Sn quadrupole magnets suitable for the LHC IR upgrade have been studied, including magnets with "cold" and "warm" iron yokes based on symmetric or asymmetric coils. This paper describes the design concepts of 2-in-1 large-aperture IR quadrupoles and compares their major performance parameters, including aperture, field gradient, field quality, electromagnetic stresses in the coils, and discuss some technological aspects of magnet fabrication.

THPCH011	Wire Compensation of Parasitic Crossings in DAFNE	positron, simulation, injection, collider	2808
	M. Zobov, D. Alesini, C. Milardi, M.A. Preger, P. Raimondi INFN/LNF, Frascati (Roma) D.N. Shatilov BINP SB RAS, Novosibirsk
	Long-range beam-beam interactions (parasitic crossings) are one of the main luminosity performance limitations for the Frascati e⁺e^- Phi-factory DAFNE. In particular, the parasitic crossings (PC) lead to a substantial lifetime reduction of both beams in collision. This puts a limit on the maximum storable current and, as a consequence, on achievable peak and integrated luminosity. In order to alleviate the problem numerical and experimental studies of the PC compensation with current-carrying wires have been performed at DAFNE. Two such wires have been installed at both ends of the KLOE interaction region. Switching on the wires in accordance with the numerical predictions, improvement in the lifetime of the "weak" beam (positrons) has been obtained at the maximum current of the "strong" one (electrons) without luminosity loss. In this paper we describe the PC effects in DAFNE, summarize the results of numerical simulations on the PC compensation with the wires and discuss the experimental measurements and observations.

THPCH028	Crystalline Beams at High Energies	lattice, dipole, focusing, quadrupole	2841
	J. Wei BNL, Upton, Long Island, New York S. Machida CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon S. Ochi, H. Okamoto HU/AdSM, Higashi-Hiroshima A. Sessler LBNL, Berkeley, California Y. Yuri JAEA, Takasaki, Takasaki
	Previously it was shown that by crystallizing each of the two counter-circulating beams, a much larger beam-beam tune shift can be tolerated during the beam-beam collisions; thus a higher luminosity can be reached for colliding beams. On the other hand, crystalline beams can only be formed at energies below the transition energy of the circular accelerators. In this paper, we investigate the formation of crystals in two types of high-transition-energy lattices, one realized by three-cell missing dipole modules and the other with negative bends. The latter type satisfies the maintenance condition for a crystalline beam*. J. Wei and A.M. Sessler, “Colliding crystalline beams”, EPAC98, p. 862. J. Wei et al. Physical Review Letters, 73 (1994) p. 3089.*J. Wei et al. Physical Review Letters, 80 (1998) p. 2606.

THPCH085	The Longitudinal Coupled Bunch Feedback for HERA-p	feedback, kicker, diagnostics, controls	2985
	M.G. Hoffmann, S. Choroba, F.E. Eints, U. Hurdelbrink, P.M. Morozov, J. Randhahn, S. Ruzin, S. Simrock, E. Vogel, R. Wagner DESY, Hamburg
	A longitudinal broadband damper system to control coupled bunch instabilities has recently been constructed and installed in the 920~GeV proton accelereator HERA-p at the Deutsches Elektronen-Synchrotron DESY. This represents one of the attempts to increase the specific luminosity at HERA by reducing the bunch length. The final bunch length is defined by the initial emittance after injection and by the acceleration process where multiply occuring coupled bunch instabilities provoke bunch length blow up at discrete energies during the ramp. The actual feedback design consists of a fast, high precision bunch centroid phase detector, a 1~kW feedback cavity with 104~MHz centre frequency and 8~MHz bandwidth (FWHM), a I/Q-vector modulator, the low level digital FPGA-board with 14 Bit ADCs and DACs and a cavity transient diagnostics. The system measures the phases of all bunches and calculates corrections in real time (bunch spacing: 96~ns) which are then applied to the beam via a longitudinal kicker. The filter deals with a slowly changing synchrotron frequency (20-80 Hz).

THPCH100	New Fast Dither System for PEP-II	feedback, controls, SLAC, closed-orbit	3029
	S.M. Gierman, S. Ecklund, R.C. Field, A.S. Fisher, P. Grossberg, K.E. Krauter, E.S. Miller, M. Petree, K.G. Sonnad, N. Spencer, M.K. Sullivan, K.K. Underwood, U. Wienands SLAC, Menlo Park, California
	The PEP-II B-Factory uses multiple feedback systems to stabilize the orbits of its stored beams and to optimize their performance in collision [1]. This paper describes an upgrade to the feedback system responsible for optimizing the overlap of colliding beams at the interaction point (IP). The effort was motivated by a desire to shorten the response time of the feedback, particularly in the context of machine-tuning tasks. We describe the original feedback system, the design for the new one, and give a status report on the installation.

THPCH103	Design and Testing of Gproto Bunch-by-bunch Signal Processor	feedback, diagnostics, damping, injection	3038
	D. Teytelman, R. Akre, J.D. Fox, A. Krasnykh, C.H. Rivetta, D. Van Winkle SLAC, Menlo Park, California A. Drago INFN/LNF, Frascati (Roma) J.W. Flanagan, T. Naito, M. Tobiyama KEK, Ibaraki
	A prototype programmable bunch-by-bunch signal acquisition and processing channel with multiple applications in storage rings has been developed at SLAC. The processing channel supports up to 5120 bunches with bunch spacings as close as 1.9 ns. The prototype has been tested and operated in five storage rings: SPEAR-3, DAFNE, PEP-II, KEKB, and ATF damping ring. The testing included such applications as transverse and longitudinal coupled-bunch instability control, bunch-by-bunch luminosity monitoring, and injection diagnostic. In this contribution the prototype design will be described and its operation will be illustrated with the data measured at the abovementioned accelerators.

THPCH104	Design and Simulation of the ILC Intra-train Orbit and Luminosity Feedback Systems	feedback, simulation, kicker, linac	3041
	G.R. White, G.R. White JAI, Oxford D. Schulte CERN, Geneva N.J. Walker DESY, Hamburg
	To maintain luminosity to within a few percent of the design at the International Linear Collider (ILC), beam stability at the IP needs to be maintained at the sub-nanometre level. To achieve the beam stability required in the presence of ground motion, multiple feedback systems are required. The baseline design calls for a 5-Hz system to control the orbit in the Linac and Beam Delivery System (BDS) and an intra-train system to address high-frequency ground motion and mechanical disturbances which cause orbit distortions at the IP between pulses enough to completely destroy the luminosity. Details of the slower feedback systems have been addressed elsewhere. The detailed design and simulation of the intra-train feedback systems are described here. This system controls the vertical position and angle at the IP such that luminosity is maximised. The system brings the beams into collision based on BPM-derived information from the initial bunches of the train. It then tunes the IP collision parameters (both position and angle) based on a fast (bunch-by-bunch) luminosity signal from the BeamCal. The system is implemented in fast digital FPGA logic, designed using Matlab's Simulink. A. Seryi et al. "Issues of Stability and Ground Motion in ILC", Nanobeam 2005.**G. White et al. "Multi-Bunch Simulations of the ILC for Luminosity Performance Studies", PAC2005.

THPCH197	Analysis of Availability and Reliability in RHIC Operations	RHIC, controls, ion, cryogenics	3257
	F.C. Pilat, P. Ingrassia, R.J. Michnoff BNL, Upton, Long Island, New York
	RHIC has been successfully operated for five years as a collider for different species, ranging from heavy ions including gold and copper, to polarized protons. We present a critical analysis of reliability data for RHIC that not only identifies the principal factors limiting availability but also evaluates critical choices at design times and assess their impact on present machine performance. RHIC availability data are compared to similar high-energy colliders and synchrotron light sources. The critical analysis of operations data is the basis for studies and plans to improve RHIC machine availability beyond the 60% typical of high-energy collider.

FRXBPA01	HERA and the Next Generation of Lepton-ion Colliders	proton, electron, lepton, collider	3621
	F.J. Willeke DESY, Hamburg
	This talk will present a summary of the physics insights gained from the lepton-hadron collider HERA and review major beam dynamics issues and lessons learned in view of LHC operation, including technical aspects related to the large number of superconducting magnets or the influence of various design choices on the overall machine performance. It will also address future plans for lepton-ion colliders, including eRHIC at BNL and the CEBAF-based ELIC, with emphasis on their luminosity reach and challenges. The talk will also mention possible high energy lepton-ion collisions, for example colliding a 1 TeV proton (or ion) beam from the Tevatron or Super-SPS with a 20-75 GeV electron beam from the ILC or CLIC (first stage).
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