EPAC08 - List of Authors (Demma, T.)

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Demma, T.

Paper	Title	Page
TUPC019	A Retarding Field Detector to Measure the Actual Energy of Electrons Participating in E-cloud Formation in Accelerators	1086
	R. Cimino, M. Commisso, T. Demma, S. Guiducci, P. Liu, A. R. Raco, V. Tullio, G. Viviani INFN/LNF, Frascati (Roma) P. Vilmercati ELETTRA, Basovizza, Trieste
	Electron cloud related phenomena can cause potentially detrimental effects on beam stability in many planned and under construction accelerators. The possibility to reduce such unwanted phenomena lies on the observation that, machine commissioning does reduce Secondary Electron Yield (SEY). Such SEY reduction (scrubbing) is due to the fact that electrons produced during e-cloud formation hit the accelerator wall, modifying their surface properties. ‘Scrubbing” has been studied only as a function of impinging electron dose but never as a function of the e-cloud electron energy. Simulations predict that the e-cloud is formed by electrons with very low energies (<50 eV). Given the potentially lower scrubbing efficiency for equal dose of very low energy electrons compared to medium energy one, it would be important to measure the actual energy of the electrons forming the cloud in real accelerators. For this reason we decided to construct an optimized retarding Field energy electrometer to be installed in accelerators. Here we will describe what solutions have been adopted during the design phase of such “home made” detector and some laboratory test will be showed and discussed.
TUPP027	Electron Energy Dependence of Scrubbing Efficiency to Mitigate E-cloud Formation in Accelerators	1592
	R. Cimino, M. Commisso, T. Demma, A. G. Grilli, P. Liu, M. Pietropaoli, V. Sciarra INFN/LNF, Frascati (Roma) V. Baglin CERN, Geneva P. Barone, A. Bonanno INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza)
	Recently built and planned accelerators, base their ability to reach design parameters, on the capability to reduce Secondary Electron Yield (SEY) during commissioning, hence mitigating the potentially detrimental effects of e-cloud driven machine limitations. This SEY reduction (called "scrubbing"), is due to the fact that the electrons of the cloud, hit the vacuum chamber wall, modifying its surface properties and reducing its SEY. This minimise any disturbing effects of the e-cloud to the beam. "Scrubbing" has been studied only as a function of impinging electron dose. In reality SEY modifications are only studied by bombarding surfaces with 300-500 eV electrons, but no scrubbing dependence on the bombarding electron energy has ever been discussed. The actual energy of the electrons of the cloud hitting the wall in real accelerators has never been measured accurately, while simulations predict very low electron energies (<50 eV). For this reason and given the peculiar behaviour observed for low energy electrons, we decided to study this dependence accurately. Here we present some preliminary results discussing eventual implications to machine commissioning procedures. R. Cimino et al. Phys. Rev. Lett 93, 14801 (2004).
TUPP030	A Formula for the Electron Cloud Map Coefficient in the Presence of a Magnetic Field	1601
	T. Demma INFN/LNF, Frascati (Roma) S. Petracca U. Sannio, Benevento
	The evolution of the electron density during multibunch electron cloud formation can be reproduced using a bunch-to-bunch iterative map formalism. The reliability of this formalism has been proved for RHIC* and LHC. The coefficients that parameterize the map function are readily obtained by fitting the results of compute-intensive electron cloud simulations. An analytic expression for the linear map coefficient that describes weak cloud behaviour from first principles has been derivied for the case of staight sections of RHIC. In this paper we generalize the model presented in ** to the case of electron cloud evolution in presence of a dipolar magnetic field and compare the results with numerical simulations. U. Iriso and S. Pegg. Phys. Rev. ST Accel. Beams 9, 071002 (2006). T. Demma et al. Phys. Rev. ST Accel. Beams 10,114401 (2007). **U. Iriso and S. Pegg. Proc. of EPAC06, pp. 357-359.
TUPP031	Electron Cloud Simulations for DAΦNE	1604
	T. Demma, R. Cimino, S. Guiducci, C. Vaccarezza, M. Zobov INFN/LNF, Frascati (Roma)
	After the first experimental observations compatible with the presence of the electron cloud effect in the DAΦNE positron ring, a systematic study has been performed regarding the electron cloud build-up. To assess the effects of the electron cloud, simulations of the cloud build up were carried out using ECLOUD. In particular, we discuss modifications to the secondary emission model, build up for various filling patterns and different wiggler magnetic field models. The obtained numerical results are compared with experimental observations.
WEPP039	Design of a 10³⁶ cm^-2 s^-1 Super-B Factory	2605
	J. Seeman, K. J. Bertsche, A. Novokhatski, M. K. Sullivan, U. Wienands, W. Wittmer SLAC, Menlo Park, California S. Bettoni CERN, Geneva M. E. Biagini, R. Boni, M. Boscolo, T. Demma, A. Drago, S. Guiducci, P. Raimondi, S. Tomassini, M. Zobov INFN/LNF, Frascati (Roma) A. Bogomyagkov, I. Koop, E. B. Levichev, S. A. Nikitin, P. A. Piminov, D. N. Shatilov BINP SB RAS, Novosibirsk G. Marchiori INFN-Pisa, Pisa E. Paoloni University of Pisa and INFN, Pisa
	Submitted for the High Luminosity Study Group for an Asymmetric 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 1 to 2 x 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 stored in low-emittance damping rings similar to those designed for a Linear Collider (LC) or the next generation light source. A LC style interaction region is included in the ring to produce sub-millimeter vertical beta functions at the collision point. A large crossing angle (±25 mrad) is used at the collision point to allow beam separation. A crab-waist scheme is used to reduce the hourglass effect and restore peak luminosity. Beam currents of about 1.8 A in 1400 bunches can produce a luminosity of 10³⁶/cm²/s with upgrade possibilities. Design parameters and beam dynamics effects are discussed.
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.