C. Milardi

Status report on DA/spl Phi/NE

DA/spl Phi/NE, the Frascati LNF /spl Phi/-factory, is providing luminosity for the KLOE experiment since July 2000. A steady increase of daily integrated luminosity in KLOE has been obtained, due to interspersed machine physics studies. The main results are: increase of single bunch luminosity by reduction of the effects of nonlinear terms in the machine, background reduction, refill of the colliding beams while keeping the KLOE detector taking data and increase of stable stored current. A fraction of machine time has been used to tune luminosity and reduce background in the DEAR configuration. The luminosity delivered to DEAR was sufficient to conclude the first phase of the experiment.

High current multibunch operation at DA/spl Phi/NE

At present the Frascati /spl Phi/-factory DA/spl Phi/NE is operating in multibunch regime with stored currents in the range of 0.5-1 A in both e/sup +/ and e/sup r/ings. A longitudinal bunch-by-bunch feedback system has been operating in each DA/spl Phi/NE main ring since the beginning of the machine commissioning. The transverse bunch-by-bunch feedback system working in the vertical plane has been implemented last year in both rings. This paper describes the performance of the feedback systems and reports the instability observations and the rise-time measurements. The present current limitations and the plans aimed at further current increase are also discussed.

DANTE: control system for DAΦNE based on Macintosh and LabVIEW

Abstract DANTE (DAΦNE new tools environment) is the control system for the DAΦNE Φ-factory under construction at the Frascati National Laboratories of the Italian Institute for Nuclear Physics (INFN). The main design goal has been to keep the software simple and easy to debug. Commercial components have been used whenever possible, with a preference for widely diffused and well established products, as opposed to“standards”. Macintosh computers are used throughout the system and LabVIEW has been chosen as development environment. We strongly oppose the “start from scratch” philosophy.

High luminosity interaction region design for collisions inside high field detector solenoid

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.

DAFNE Interaction Regions upgrade

DAΦNE, the Frascati Φ-factory, has recently completed experimental runs for the three main detectors, KLOE, FINUDA and DEAR achieving 1.6x10 32 cm -2 s -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.

Simulation of Crab Waist Collisions in DAΦNE with KLOE-2 Interaction Region

After the successful completion of the SIDDHARTA experiment run with crab waist collisions, the electron-positron collider DAΦNE has started routine operations for the KLOE2 detector. Similarly to the SIDDHARTA configuration, the new interaction region exploits the crab waist collision scheme, but features certain complications including the experimental detector solenoid, compensating anti-solenoids, and tilted quadrupole magnets, that lead to significant coupling of the horizontal and vertical betatron motion. It is not immediately obvious if the crab waist scheme would be as efficient in the strongly coupled case as it was in the uncoupled configuration. We have performed simulations of beam-beam interactions in the collider taking into account the real machine nonlinear lattice. In particular, we have evaluated the effect of crab waist sextupoles and beam-beam interactions on the collider dynamical aperture and energy acceptance. A new betatron tune working point has been proposed for the DAΦNE electron ring, and its implementation resulted in more than 20% background reduction and injection efficiency improvement. Exploiting this working point has allowed reaching the best present luminosity of 2.0 × 1032 cm-2 s-1. The numerical simulations have shown that for the given bunch currents in collision, the powering of the crab waist sextupoles should decrease the beam core blow up by a factor of 2 indicating that even higher luminosity can be achieved in DAΦNE thus encouraging further collider optimization.

PRESENT STATUS OF THE DAΦNE UPGRADE AND PERSPECTIVES

The DAΦNE collider has been recently upgraded in order to implement a new collision scheme based on large Piwinski angle and cancellation of the synchro-betatron resonances by means of electromagnetic sextupoles (Crab-Waist compensation). The novel approach has proved to be effective in improving beam-beam interaction and collider luminosity. The results and the measurements taken during commissioning as well as the perspectives for the SIDDHARTA run are presented and discussed.

Feasibility study of a 2 GeV lepton collider at DAFNE

While the main advances in the standard model probing require the construction of very high-energy colliders, many open questions still remain which can be answered by exploring low and medium energy regions. In this framework we are investigating the possibility of upgrading the /spl phi/-factory DA/spl phi/NE from the energy of 1.02 GeV c.m. up to the neutron-antineutron threshold (about 2 GeV c.m.) using the existing systems and structures. The luminosity required by the experiments for a light quark factory is of the order of few 10/sup 31/ cm/sup -2/ s/sup -1/, easily achievable in the particle factory era. The very first results of the feasibility study are presented.

Developments in linear and non-linear DA/spl Phi/NE lattice

The agreement between the DA/spl Phi/NE model and the measured machine parameters (betas, dispersion etc) has further improved in the 2002 runs. A better dispersion function control has been obtained by modifying the closed orbit correction algorithm, which now includes corrector strength minimization. The model has been integrated in the accelerator control system, providing a faster and reliable tool for fine and on-line machine optics tuning. New measurements, such as the machine second order dispersion, have proved to be very effective in studying the second order terms in the rings. Measurements of second order chromaticity and tune shift on amplitude have extended our knowledge about the lattice up to the third order.

DAΦNE beam instrumentation

DAΦNE, the Frascati Φ-Factory, is now under commissioning. The accelerator complex is composed of a linac, an accumulator-damping ring, and two separate main rings, one for electrons and the other for positrons, with two interaction regions in which the experiments will be placed. In order to achieve the luminosity goal, high performance instrumentation and beam diagnostics have been installed. Some of the relevant beam measurements performed are: beam emittance, transverse and longitudinal dimensions, beam positions and tunes, overlap in the interaction points, and luminosity. An overview of the diagnostic instrumentation of the accelerator complex is given together with measurement examples and discussion of operational experiences.