No Arabic abstract
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.
DAFNE, the Frascati F-factory, has recently completed experimental runs for the three main detectors, KLOE, FINUDA and DEAR achieving 1.6x10E+32 cm-2s-1 peak and 10 pb-1 daily integrated luminosities. Improving these results by a significant factor requires changing the collision scheme. For this reason, in view of the SIDDHARTA detector installation, relevant modifications of the machine have been realized, aimed at implementing a new collision scheme based on a large Piwinski angle and crab-waist, together with several other hardware modifications involving injection kickers, bellows and beam pipe sections.
The results of 2002 DAFNE operation for the two experiments KLOE and DEAR are described. During 2003 a long shutdown has been dedicated to the installation of new Interaction Regions (IR) and to hardware modifications and upgrades. In the last section optics studies and performances expectations for the new machine configuration are reported.
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.
A beam optics scheme has been designed for the Future Circular Collider-e+e- (FCC-ee). The main characteristics of the design are: beam energy 45 to 175 GeV, 100 km circumference with two interaction points (IPs) per ring, horizontal crossing angle of 30 mrad at the IP and the crab-waist scheme [1] with local chromaticity correction. The crab-waist scheme is implemented within the local chromaticity correction system without additional sextupoles, by reducing the strength of one of the two sextupoles for vertical chromatic correction at each side of the IP. So-called tapering of the magnets is applied, which scales all fields of the magnets according to the local beam energy to compensate for the effect of synchrotron radiation (SR) loss along the ring. An asymmetric layout near the interaction region reduces the critical energy of SR photons on the incoming side of the IP to values below 100 keV, while matching the geometry to the beam line of the FCC proton collider (FCC-hh) [2] as closely as possible. Sufficient transverse/longitudinal dynamic aperture (DA) has been obtained, including major dynamical effects, to assure an adequate beam lifetime in the presence of beamstrahlung and top-up injection. In particular, a momentum acceptance larger than +/-2% has been obtained, which is better than the momentum acceptance of typical collider rings by about a factor of 2. The effects of the detector solenoids including their compensation elements are taken into account as well as synchrotron radiation in all magnets. The optics presented in this paper is a step toward a full conceptual design for the collider. A number of issues have been identified for further study.
Following successful experience at the BNL AGS, FNAL Tevatron, and CERN SPS, an AC Dipole will be adopted at the LHC for rapid measurements of ring optics. This paper describes some of the parameters of the AC dipole for the LHC, scaling from performance of the FNAL and BNL devices.