Ohmi, K.

Paper	Title	Page
MOPP059	Study for ILC Damping Ring at KEKB	676
	K. Ohmi, J. W. Flanagan, H. Fukuma, K.-I. Kanazawa, H. Koiso, M. Masuzawa, Y. Ohnishi, K. Oide, Y. Suetsugu, M. Tobiyama KEK, Ibaraki M. T.F. Pivi SLAC, Menlo Park, California
	ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.
TUPC040	Measurements of Beam-beam Kick using a Gated Beam-position Monitor under Crabbing Collision at KEKB	1143
	T. Ieiri, H. Fukuma, Y. Funakoshi, M. Masuzawa, K. Ohmi, M. Tobiyama KEK, Ibaraki
	KEKB is a double-ring electron/positron collider with a horizontal crossing-angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. A gated beam-position monitor is a tool to measure the beam-beam effects. A beam-beam kick curve was measured by comparing the beam position between colliding and non-colliding bunches, while shifting the beam orbit at the interaction point (IP). An effective horizontal beam size at the IP was obtained from a linear part of the beam-beam kick around the central orbit. The estimated beam size agreed with a calculated value including the dynamic effects. It was confirmed that the effective horizontal beam size was reduced by the crabbing collision, as expected from a calculation with a rigid Gaussian model. When a horizontal orbit offset was larger than a beam size, however, we found that the measured beam-beam kick curve deviated from calculated values using the Gaussian model. The result suggests that the beam profile might enlarge horizontally in the peripheral part.
WEPP013	Increasing the Integrated Luminosity of SLHC by Levelling via the Crossing Angle	2554
	J.-P. Koutchouk, G. Sterbini CERN, Geneva K. Ohmi KEK, Ibaraki
	With an increase of luminosity by a factor of 10, the luminosity lifetime in an upgraded LHC would be limited to a few hours. Furthermore, schemes relying on stronger focusing and reduced beam current increase (which are intrisically less dangerous for machine protection) are penalized by a very short lifetime of around 2 hours. We show in this paper that the "early separation" scheme and/or crab cavities scheme lend themselves to a very efficient luminosity leveling scheme. It allows constant luminosity over many hours as well as a significant increase of integrated luminosity above the performance announced so far. This is achieved by adjusting the crossing angle rather than the beam size by means of a bump closed inside the experimental straight section, i.e. operationally simple. The initially large crossing angle reduces the beam-beam tune shift, allowing an increased beam current and higher performance for lower pile-up in the detector and lower energy deposition in the triplet. The impact of the required large Piwinski angle is investigated.
WEPP034	Study of Beam-beam effect at various collision scheme in LHC	2593
	K. Ohmi KEK, Ibaraki
	LHC is designed as two major collision points with finite crossing angle of 140μrad (half). The Piwinski angle is 0.4 for the design. Upgrade plans have been studied to increase the luminosity 10 times. Large Piwinski angle scheme is one of the option for the upgrade. The one turn map with the two beam-beam interactions can be expanded by Taylor series. Analyzing the one turn map gives information of resonance behavior of the beam-beam interactions. We discuss the one turn map for the design LHC and upgrade scheme.
WEPP035	Study of Beam-beam Issue for KEKB Crab Crossing	2596
	K. Ohmi, J. W. Flanagan, Y. Funakoshi, N. Iida, H. Koiso, A. Morita, Y. Ohnishi, K. Oide, Y. Seimiya KEK, Ibaraki
	A short lifetime at collision is one of the limits on luminosity performance at KEKB in crab crossing mode. The beam-beam halo was evaluated via simulation. The beam lifetime and profile were measured for various beam conditions, vertical emittances, tunes and collision offsets. We discuss why the lifetime is shortened by the beam-beam interaction.
WEXG02	Crabbed Waist Collisions in DAΦNE and Super-B Design	1898
	P. Raimondi, D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, C. Milardi, F. Murtas, 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. Zobov INFN/LNF, Frascati (Roma) N. Arnaud, D. Breton, P. Roudeau, A. Stocchi, V. Variola, B. F. Viaud LAL, Orsay S. Bettoni CERN, Geneva P. Branchini roma3, Rome M. Esposito Rome University La Sapienza, Roma I. Koop, E. B. Levichev, P. A. Piminov, D. N. Shatilov, V. V. Smaluk BINP SB RAS, Novosibirsk K. Ohmi KEK, Ibaraki E. Paoloni University of Pisa and INFN, Pisa M. Schioppa INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza) D. Teytelman SLAC, Menlo Park, California P. Valente INFN-Roma, Roma
	The new idea of increasing the luminosity of a collider with crabbed waist collisions and first experimental results from DAΦNE using this concept are presented. Consequences for the design of future factories will be discussed. An outlook to the performance reach with crabbed waist collisions is given, with emphasis on future B Factories.
	Slides
WEPP036	DAΦNE Setup and Operation with the Crab-Waist Collision Scheme	2599
	C. Milardi, D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, F. Murtas, L. Pellegrino, M. A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov INFN/LNF, Frascati (Roma) N. Arnaud, D. Breton, P. Roudeau, A. Stocchi, V. Variola, B. F. Viaud LAL, Orsay S. Bettoni CERN, Geneva P. Branchini roma3, Rome M. Esposito Rome University La Sapienza, Roma I. Koop, E. B. Levichev, P. A. Piminov, D. N. Shatilov BINP SB RAS, Novosibirsk K. Ohmi KEK, Ibaraki E. Paoloni University of Pisa and INFN, Pisa M. Schioppa INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza) V. V. Smaluk BINP, Novosibirsk P. Valente INFN-Roma, Roma
	In the second half of 2007 a major upgrade has been implemented on the Frascati DAΦNE collider in order to test the novel idea of Crab Waist collisions. New vacuum chambers and permanent quadrupole magnets have been designed, fabricated and installed to realize the new configuration. At the same time the performances of relevant hardware components, such as fast injection kickers and shielded bellows have been improved relying on new design concepts. The collider has been successfully commissioned in this new configuration. The paper describes the new layout as well as several experimental results about linear and non-linear optics setup and optimization, damping of beam instabilities and discusses the obtained luminosity performances.