| Paper |
Title |
Page |
| MPPP024 |
Recent Observations on a Horizontal Instability in the DAFNE Positron Ring
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1841 |
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- A. Drago, M. Zobov
INFN/LNF, Frascati (Roma)
- D. Teytelman
SLAC, Menlo Park, California
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A strong horizontal instability limits the maximum positron current storable in the DAFNE Phi-Factory. A powerful feedback system makes it possible to store and collide up to 1250 mA of positron current in 105 bunches. Nevertheless, a much higher current (> 2.4A) has been successfully stored in the twin electron ring. Measurements have been carried out to understand the positron current limit and to characterize the behavior of the horizontal instability at high current with different bunch patterns. Grow/damp turn-by-turn data obtained by turning off the horizontal feedback have been acquired and analyzed. Spectral analysis and grow rates of the instability are shown. In particular, the -1 mode has strong evidence and fast grow rate. Its grow rate behavior is analyzed at different beam currents and bunch patterns.
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| TPPT060 |
Design of a Multi-Cell, HOM Damped Superconducting Cavity for the Strong RF Focusing Experiment at DAFNE
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3505 |
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- A. Gallo, D. Alesini, C. Biscari, R. Boni, F. Marcellini, M. Zobov
INFN/LNF, Frascati (Roma)
- C. Pagani
DESY, Hamburg
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A strong RF focusing experiment to be performed at the DAFNE Phi-factory has been proposed to create and observe a bunch length modulation along the ring. The very large RF gradient required to reach the strong focusing regime can only be obtained by using a multi-cell superconducting cavity. Moreover, in order to demonstrate the feasibility of a high luminosity collider based on this principle, a total multibunch current of the order of 1A has to be stored under stable conditions in this regime. A 1.3 GHz 7-cells cavity has been designed for this purpose, based on the TESLA geometry with small modifications of the basic cell to comply with the DAFNE revolution frequency. The number of cells has been changed from 9 to 7 to reduce the number of the cavity HOMs, while the beam tubes have been enlarged to let most of the HOMs propagate and be damped by room-temperature ferrite rings. The modes of the first longitudinal band, which include the accelerating TM010_pi, do not propagate in the beam tubes and have been studied with special care to prevent the overlap with the bunch revolution harmonics and to cure the effects of coupling to the synchrotron tune sidebands.
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| ROAA001 |
DAFNE Operation and Plans for DAFNE2
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112 |
| |
- M. Zobov, D. Alesini, G. Benedetti, M.E. Biagini, C. Biscari, R. Boni, M. Boscolo, A. Clozza, G.O. Delle Monache, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, G. Mazzitelli, C. Milardi, L. Pellegrino, M.A. Preger, P. Raimondi, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, C. Vaccarezza, M. Vescovi
INFN/LNF, Frascati (Roma)
- J.D. Fox, D. Teytelman
SLAC, Menlo Park, California
- E. Levichev, P.A. Piminov, D.N. Shatilov
BINP SB RAS, Novosibirsk
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The e+e- collider DAFNE, a 1.02 Gev c.m. Phi-factory, has exceeded 1.2 1032 cm-2s-1 peak luminosity with 7.5 pb-1 maximum daily integrated luminosity. At the present performance the physics program of the three main experiments DEAR, FINUDA and KLOE will be completed by mid 2007. In this paper we describe the steps which have led to the luminosity improvement and present proposals for the upgrade of the collider towards higher energy and/or luminosity. The main accelerator issues on which we are planning to rely for this purpose, such as lattices with negative momentum compaction, strong RF focusing, design of high field magnets and Linac upgrade, are discussed in detail.
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| ROAA003 |
Proposal of an Experiment on Bunch Length Modulation in DAFNE
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336 |
| |
- C. Biscari, D. Alesini, G. Benedetti, M.E. Biagini, R. Boni, M. Boscolo, A. Clozza, G.O. Delle Monache, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, G. Mazzitelli, C. Milardi, L. Pellegrino, M.A. Preger, P. Raimondi, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, C. Vaccarezza, M. Vescovi, M. Zobov
INFN/LNF, Frascati (Roma)
- J.M. Byrd, F. Sannibale
LBNL, Berkeley, California
- J.D. Fox, D. Teytelman
SLAC, Menlo Park, California
- E. Levichev, P.A. Piminov, D.N. Shatilov
BINP SB RAS, Novosibirsk
- C. Pagani
INFN/LASA, Segrate (MI)
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Obtaining very short bunches is a challenge for colliders and Coherent Synchrotron Radiation sources as well. The modulation of the bunch length in a strong RF focusing regime has been proposed, corresponding to a large value of the synchrotron tune. A ring structure where the dependence of the longitudinal position of a particle on its energy (R56) along the ring oscillates between large positive and negative values can produce a bunch length modulation. The synchrotron frequency can be tuned both by means of the rf voltage and by the integral of R56, down to the limit of zero value corresponding to the isochronicity condition. We present here the proposal of bunch length modulation along the DAFNE rings. Its lattice can be tuned to positive or negative momentum compaction, or to structures in which the two arcs are alternately set to positive/negative integrals of R56. With the proposed installation of an extra RF system at 1.3 GHz, experiments on bunch length modulation both in the high and low synchrotron tune regimes can be realized.
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| RPAT098 |
Phase-Space Dynamic Tracking by a Two Pickups Data Acquisition System
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4326 |
| |
- A. Drago, M.E. Biagini, S. Guiducci, C. Milardi, M.A. Preger, C. Vaccarezza, M. Zobov
INFN/LNF, Frascati (Roma)
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A two pickups dynamic tracking data acquisition system has been developed at LNF for the DAFNE Phi-factory. Two oscilloscopes sample horizontal and vertical sum and difference signals from two pickups simultaneously; the sampling clock is locked to the DAFNE timing system. A horizontal kick excites the beam motion and initiates the acquisition. Turn-by-turn signals are converted to beam position and stored on a server in a database using timestamp labels. Oscillation amplitude versus time, phase space distribution and frequency domain analysis are shown for several lattices and different settings of sextupoles and octupoles. Results are used to check the DAFNE non-linear model.
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| FPAP001 |
Electron Cloud Build-Up Study for DAFNE
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779 |
| |
- C. Vaccarezza, R. Cimino, A. Drago, M. Zobov
INFN/LNF, Frascati (Roma)
- G. Bellodi
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
- K. Ohmi
KEK, Ibaraki
- M.T.F. Pivi
SLAC, Menlo Park, California
- G. Rumolo
GSI, Darmstadt
- D. Schulte, F. Zimmermann
CERN, Geneva
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After the first experimental observations compatible with the presence of the electron cloud effect in the DAFNE positron ring, a more systematic study has been performed regarding the e-cloud build-up and related instability. The measured field map of the magnetic field has been taken into account in the simulation for elements present in the four 10 m long bending sections, representing 40% of the whole positron ring. The simulation results obtained with different codes are presented and compared with the recent experimental observations performed on the beam instabilities and the vacuum behavior of the positron ring.
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| RPPP001 |
Commissioning and First Measurements on the CTF3 Chicane
|
785 |
| |
- A. Ghigo, D. Alesini, G. Benedetti, C. Biscari, M. Castellano, A. Drago, D. Filippetto, F. Marcellini, C. Milardi, B. Preger, M. Serio, F. Sgamma, A. Stella, M. Zobov
INFN/LNF, Frascati (Roma)
- R. Corsini, T. Lefevre, F. Tecker
CERN, Geneva
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The transfer line between the linac and the first recombination ring (Delay Loop) of the CTF3 project hs been installed at CERN in spring-summer 2004. In the transfer line a magnetic chicane is used to tune the length of the bunches coming from the linac in order to minimize the Coherent Synchrotron Radiation contribution to the beam energy spread in the recombination system. The first measurements of the beam parameters at several linac and stretcher settings are described. We report the compression curve as a function of the optical parameter R56 representing the dependence of the longitudinal position of a particle on its energy, obtained by measuring the bunch length with a 3 GHz RF deflector.
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