An innovative interaction region has been recently conceived and realized on the Frascati DAΦNE lepton collider. The concept of tight focusing and small crossing angle adopted to achieve high luminosity in multibunch collisions has evolved towards enhanced beam focusing at the interaction point with large horizontal crossing angle, thanks to a new compensation mechanism for the beam-beam resonances. The novel configuration has been tested with a small detector without solenoidal field yielding a remarkable improvement in terms of peak as well as integrated luminosity. The high luminosity interaction region has now been modified to host a large detector with a strong solenoidal field which significantly perturbs the beam optics introducing new design challenges in terms of interaction region optics design, beam transverse coupling control and beam stay clear requirements. Interaction region design criteria as well as the first luminosity results obtained with the beams in collision are presented and discussed.

The electron-positron collider DAPhiNE, the Italian Phi factory, has been recently upgraded in order to implement an innovative collision scheme based on large crossing angle, small beam sizes at the crossing point, and compensation of beam-beam interaction by means of sextupole pairs creating a "crab-waist" configuration in the interaction region. Experimental tests of the novel scheme exhibited an increase by a factor of 3 in the peak luminosity of the collider with respect to the performances reached before the upgrade. In this Letter we present the new collision scheme, discuss its advantages, describe the hardware modifications realized for the upgrade, and report the results of the experimental tests carried out during commissioning of the machine in the new configuration and standard operation for the users.

Long-range beam-beam interactions (parasitic crossings) were one of the main luminosity performance limitations for the lepton F-factory DAFNE in its original configuration. In particular, the parasitic crossings led to a substantial lifetime reduction of both beams in collision. This puts a limit on the maximum storable current and, as a consequence, on the achievable peak and integrated luminosity. In order to mitigate the problem, numerical and experimental studies of the parasitic crossings compensation by current-carrying wires have been done. During the operation for the KLOE experiment two such wires have been installed at both ends of the interaction region. They produced a relevant improvement in the lifetime of the weak beam (positrons) at the maximum current of the strong one (electrons) without luminosity loss, in agreement with the numerical predictions. The same compensating mechanism has been adopted during the run for the FINUDA experiment as well, with less evident benefits than in the previous case. The interplay between nonlinearities originating from the beam-beam interaction and the ring lattice has been studied by theoretical simulation and experimental measurements. Compensation procedures have been set up relying on the electromagnetic octupoles installed on both rings and used in addition to wire compensation. In this paper the parasitic crossings effects in the DAFNE interaction regions and their compensation by wires and octupoles are described. A detailed theoretical analysis of the interplay about different non-linearities is presented; eventually experimental measurements and observations are discussed.

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 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 the achievable peak and integrated luminosity. In order to alleviate the problem numerical and experimental studies of the parasitic crossings 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 agreement 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 parasitic crossings effects in DAFNE, summarize the results of numerical simulations on their compensation with the wires and discuss the experimental measurements and observations.

The e+e- collider DAΦNE, a 1.02 GeV c.m. Φ-factory, has reached a peak luminosity of about 1.4×10 32 cm -2 s -1 and a peak integrated luminosity in one day of about 8.6 pb -1 . With the current rates the physics program of the three main experiments DEAR, FINUDA and KLOE will be completed by the end of 2007. In this paper we describe in detail the steps which have led to the luminosity improvement and the options for the upgrade of the collider towards higher energy and/or luminosity.

SPARC and SPARX are two different initiatives toward an X-ray FEL SASE source at LNF. SPARC is a high gain FEL project devoted to provide a source of visible and VUV radiation while exploiting SASE mechanism. An advanced Photo-Injector system, emittance self-compensating RF-gun plus a 150 MeV Linac, will inject a high quality e-beam into the undulator to generate high brilliance FEL radiation in the visible region at the fundamental wavelength, (530 nm). The production of flat top drive laser beams, high peak current bunches, and an emittance compensation scheme will be investigated together with the generation of higher harmonic radiation in the VUV region. SPARX is the direct evolution of such a high gain SASE FEL towards the 13.5 and 1.5 nm operating wavelengths, at 2.5 GeV. The first phase of the SPARX project, fiinded by Government Agencies, will be focused on R&D activity on critical components and techniques for future X-ray facilities as described in this paper.

DAFNE operation restarted in September 2003, after a six month shut-down for the installation of FINUDA, a magnetic detector dedicated to the study of hypernuclear physics. FINUDA is the third experiment running on DAFNE and operates while keeping on place the other detector KLOE. During the shut-down both Interaction Regions have been equipped with remotely controlled quadrupoles in order to operate at different solenoid fields. Among many other hardware upgrades one of the most significant is the reshaping of the wiggler pole profile to improve the field quality and the machine dynamic aperture. Commissioning of the collider in the new configuration has been completed in short time. The peak luminosity delivered to FINUDA has reached 6 10^31 s-1cm-2, with a daily integrated value close to 4 pb-1.

The Frascati F-Factory DAFNE has been delivering luminosity to the KLOE, DEAR and FINUDA experiments since year 2000. Since April 2004 the KLOE run has been resumed and recently peak luminosity of 1.0x1032 cm-2s-1 and integrated luminosity of 6.2 pb-1/day have been achieved. The scientific program of the three high-energy experiments sharing DAFNE operation will be completed approximately by the end of year 2006. A scientific program for DAFNE beyond that date has not been defined yet and it is matter of discussion in the high-energy physics and accelerator physics communities. In this paper we present some future scenarios for DAFNE, discussing the expected ultimate performances of the machine as it is now and addressing the design for an energy and/or luminosity upgrade. The options presented in the following are not exhaustive and they are intended to give a glance of what is doable using the existing infrastructures.

The first part of the CTF3 transfer line is already installed. It includes a chicane in which, because of its very flexible lattice and large aperture vacuum chamber, the bunch length can change in a wide range.The chicane can be used as a stretcher to lengthen the pulses coming from the linac in order to reduce the coherent synchrotron radiation (CSR) in the recombination rings. A possible use as a bunch compressor is also foreseen in order to make CSR experiments and to characterize beam instrumentation. This paper describes the final design of the vacuum chambers, including beam diagnostics components, and their laboratory tests. The installation status of the magnetic and vacuum chamber components together with the ancillary systems is reported.

In the CTF3 complex the Linac pulse train, 1.4 μs long, is squeezed to a 140 ns train with a peak current 10 times higher (35A) by means of the bunch interlacing technique. The compressor system consists of two rings; the first (Delay Loop) multiplies the Linac bunch frequency by a factor 2, the second (Combiner Ring) by another factor 5. The lattices of the rings and transfer lines allow fine tuning of the trajectory and bunch length. The beam impedance budget is minimized to avoid energy spread growth. The layout of the rings and the intermediate transfer lines are shown. Design of special components of the rings and measurements on the prototypes are presented.

Since the last EPAC2000 Conference, both the peak and integrated luminosity of the ee collider DAΦNE, Italian Φ–factory, have grown by an order of magnitude. In this paper we describe the steps that have led to the luminosity increase and discuss our plans for further luminosity upgrade.

DAΦNE [1] is the e+ eΦ-Factory presently under commissioning at INFN Frascati. The two beams have been successfully injected and stored and the optics has been tuned to operate in collision mode. The optics solutions adopted to solve the problems set by the r quirements of a high intensity, high luminosity Φ-Factory are described. Preliminary measurements of the optical parameters are presented and compared with a machine model.

Electron storage rings are the most promising sources for free electron lasers at short wavelengths. The main properties of such devices are recalled, and the problems related to their use as FEL sources are discussed.

The present duty factor of the 400 MeV Frascati National Laboratories Linac (8x10−4) can be made to approach unity by using an electron storage ring as a pulse stretcher: resonant extraction near an m/3 resonance by means of sextupolar nonlinearities in the ring allows slow extraction of the stored current with small energy spread. The feasibility of a machine,capable of 100µA average current and 10−3 energy spread between 200 and 500 MeV is investigated. The necessary modifications to the Linac are indicated. Expected parameters of the extracted beam are presented.

The Adone vacuum chamber has been recently replaced aiming at the reduction of the longitudinal coupling impedance. Measurements in this new condition show that the bunch length is now of the same order of magnitude of the vacuum pipe. We present the results and compare them with the previous measurements. The Adone vacuum chamber has been recently substituted with a new one, mainly to improve the performance of the vacuum system, and to install 24 beam position monitors. With respect to the previous one, care has been taken to provide a smoother surface to the beam environment. Namely, most bellows (46 out of 50) have been provided with RF shields-and the vacuum pump ports masked by oblong holes to increase the associated waveguide cutoff beyond the characteristic frequencies of the bunches. In these new conditions the bunch length in Adone has been measured for different values of energy and RF voltage, and with bunch current ranging from 1 to 40 mA. Measured data are presented, compared with the previous ones, and used to get information