INFN/LNF, Frascati (Roma)
LAL, Orsay
CERN, Geneva
roma3, Rome
Rome University La Sapienza, Roma
BINP SB RAS, Novosibirsk
KEK, Ibaraki
BINP, Novosibirsk
SLAC, Menlo Park, California
INFN-Roma, Roma
In 2007 DAΦNE was upgraded to operate in a regime of large Piwinski angle, with a novel IR optics, reduced vertical beta at the interaction point, and additional sextupoles providing for crab waist collisions. The specific luminosity was boosted by more than a factor of four, and the peak luminosity was more than doubled with respect to the maximum value obtained with the original collider configuration. The DAΦNE commissioning as well as the first experience with large Piwinski angle and crab waist collisions scheme will be reported.
INFN/LNF, Frascati (Roma)
UCLA, Los Angeles, California
Istituto Nazionale di Fisica Nucleare, Milano
INFN-Roma II, Roma
ENEA C.R. Frascati, Frascati (Roma)
University of Tehran, Tehran
INFN-Roma, Roma
One of the main goals of the SPARC high brightness photoinjector is the experimental demonstration of the emittance compensation process while compressing the beam with the velocity bunching technique, also named RF compressor. For this reason, the first two S-band travelling wave accelerating structures downstream of the RF gun are embedded in a long solenoid, in order to control the space charge induced emittace oscillations during the compression process. An RF deflecting cavity placed at the exit of the third accelerating structure allows bunch length measurements with a resolution of 50 μm. During the current SPARC run a parametric experimental study of the velocity bunching technique has been performed. The beam bunch length and projected emittance have been measured at 120 MeV as a function of the injection phase in the first linac, and for different solenoid field values. In this paper we describe the experimental layout and the results obtained thus far. Comparisons with simulations are also reported.
Università di Roma II Tor Vergata, Roma
INFN/LNF, Frascati (Roma)
Rome University La Sapienza, Roma
INFN-Roma II, Roma
ENEA C.R. Frascati, Frascati (Roma)
The SPARC photoinjector drives a SASE FEL to perform several experiments both for the production of high brightness electron beam and for testing new scheme of SASE radiation generation. The control of the beam properties, in particular at the level of the slice dimension, is crucial in order to optimize the FEL process. We report the different measurements performed in order to characterize the slice properties of the electron beam.
INFN/LNF, Frascati (Roma)
New injection stripline kickers are operating since December 2007 at the DAΦNE collider. They are designed to operate with very short pulse generators to perturb only the injected bunch and the two stored adjacent ones at 2.7 ns and are a test for the design of the fast kickers of the damping ring of the International Linear Collider (ILC). Stripline frequency response and impedance measurements have been performed to characterize the structure and are compared to the simulation results. Operational performances are also described, pointing out the problems occured and the flexibility of the stripline structure that worked with both the short and the old pulse generators and has been used as an additional damping kicker to improve the efficiency of the horizontal multibunch feedback system.
INFN/LNF, Frascati (Roma)
STAAR/AWR Corporation, Mequon
SLAC, Menlo Park, California
CERN, Geneva
To suppress the vertical beam instability in the CTF3 Combiner Ring caused by vertical trapped modes in the rf deflectors, two new devices have been constructed. In the new structures special antennas absorb the power released by the beam to the modes. They have been realized in aluminium to reduce the costs and delivery time and have been successfully installed in the ring. In the paper we illustrate the electromagnetic design, the realization procedures, the rf measurement and high power test results.
PSI, Villigen
INFN/LNF, Frascati (Roma)
RF deflectors are crucial diagnostic tools for bunch length and slice emittance measurements with sub-picosecond resolution. Their use is essential in commissioning and operation of VUV and X-ray FELs. The 250MeV FEL injector, under construction at PSI, will use two of them. The first one will be installed after the gun at low energy (~7MeV), the second one at the end of the Linac at high energy (250MeV). The first RF deflector consists of a single cell standing wave cavity working on the TM110 deflecting mode, and tuned at 2997.912 MHz (frequency of the linac structures). In this note we report the motivation of this measurement, beam dynamics and beam diagnostics considerations and the RF design and simulations of this cavity.
INFN/LNF, Frascati (Roma)
CERN, Geneva
The CLIC drive beam current, produced by the 1 GHZ fully loaded Linac, will be multiplied by a factor of 24 by the frequency multiplication system, to generate the high power beam representing the CLIC power source. The frequency multiplication system is composed by one delay loop plus two combiner rings. All rings will be isochronous, will contain trajectory tuning wigglers, and all magnets will be normal conducting. The design of the rings, with special emphasis on the rf deflectors characteristics, is presented.
INFN/LNF, Frascati (Roma)
Istituto Nazionale di Fisica Nucleare, Milano
CEA, Gif-sur-Yvette
INFN-Roma II, Roma
ENEA C.R. Frascati, Frascati (Roma)
SOLEIL, Gif-sur-Yvette
INFN-Roma, Roma
University of Tehran, Tehran
UCLA, Los Angeles, California
The SPARC project foresees the realization of a high brightness photo-injector to produce a 150-200 MeV electron beam to drive 500 nm FEL experiments in SASE, Seeding and Single Spike configurations. The SPARC photoinjector is also the test facility for the recently approved VUV FEL project named SPARX. The second stage of the commissioning, that is currently underway, foresees a detailed analysis of the beam matching with the linac in order to confirm the theoretically prediction of emittance compensation based on the “invariant envelope” matching , the demonstration of the “velocity bunching” technique in the linac and the characterisation of the spontaneous and stimulated radiation in the SPARC undulators. In this paper we report the experimental results obtained so far. The possible future energy upgrade of the SPARC facility to produce UV radiation and its possible applications will also be discussed.
Rome University La Sapienza, Roma
INFN/LNF, Frascati (Roma)
We discuss the use of non resonant bead pull technique for measuring fields in standing wave accelerating structures. From the Steele perturbation theory, one can derive the relation between the magnitude and phase of the field in the cavity and the complex reflection coefficient. The effect of the bead size, the calibration of the bead and the comparison with the more common resonant techniques are addressed. As an example, we discuss the measurement on a X-band bi-periodic cavity proposed for linearizing emittance at the Frascati photo-injector SPARC.
UCLA, Los Angeles, California
INFN/LNF, Frascati (Roma)
Rome University La Sapienza, Roma
A hybrid photoinjector, which we present here, consists of a 6-cell traveling wave structure with a standard 1.6-cell RF gun attached to the one end and a 3-m long linac following for further acceleration. With this structure, no reflection observed at the input port. This enables to build the accelerator without a circulator which limits the power and the frequency of RF. From the beam dynamics point of view, the beam is produced as the normal RF guns and gets short by velocity bunching in the traveling wave section right after the gun. The peak current can reach more than 1 kA, with about 2 mm.mrad of the emittance at 20 MeV. We discuss more details about the beam dynamics as well as the RF structure.
EPFL, Lausanne
INFN/LNF, Frascati (Roma)
CERN, Geneva
BNL, Upton, Long Island, New York
UMAN, Manchester
A detailed knowledge of the beam coupling impedance of the CERN Super Proton Synchrotron (SPS) is required in order to operate this machine with a higher intensity for the foreseen Large Hadron Collider (LHC) luminosity upgrade. A large number of Beam Position Monitors (BPM) is currently installed in the SPS, and this is why their contribution to the SPS impedance has to be assessed. This paper focuses on electromagnetic simulations and bench measurements of the longitudinal and transverse impedance generated by the horizontal and vertical BPMs installed in the SPS machine.