G. Delle Monache

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.

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.

Proposal of an Experiment on Bunch Length Modulation in DAφNe

Obtaining very short bunches is an issue especially for colliders but also for CSR sources. The modulation of the bunch length in a strong rf focusing regime had been proposed, corresponding to a high value of the synchrotron tune. A ring structure where the function R56 along the ring oscillates between large positive and negative values will produce bunch length modulation. The synchrotron frequency can be tuned both by the rf power and by the integral of the function R56, up to the limit of zero value corresponding to the isochronicity condition. The proposal of a bunch length modulation along the ring in DAΦNE is here described. DAΦNE lattice can be tuned to positive or negative momentum compaction values, or to structures in which the two arcs are respectively set to positive/negative integrals of the R56 function. With the installation of an extra rf system at 1.3 GHz, experiments on bunch length modulation both in the regime of high and low synchrotron tune can be realized.

DAΦPNE setup and performances during the second FINUDA run

Beam operations at DAΦPNE restarted in October 2006 after a four months shut-down to remove the KLOE experimental detector and to install the FINUDA one. This period has been also used for maintenance and implementation of several upgrades. Already in the first two months of operation the peak and integrated luminosity exceeded the values obtained during the first FINUDA run by 20%, and have been steadily improving toward the end of the operation. By June 2007 ˜ 1 fb-1 integrated luminosity has been logged by the experiment. The collider performances during the run are presented together with the improvements obtained in terms of beam dynamics and beam-beam behaviour coming from several collider modifications.

100 bunch DA/spl Phi/NE operation

The DA/spl Phi/NE collider has been operating by filling 100 consecutive buckets out of the available 120 with a gap to avoid ion trapping in the electron beam. To reduce the effect of the parasitic crossings the crossing angle has been increased up to 29 mrad and the horizontal beta function at the interaction point lowered down to 1.7 m. Moreover both transverse and longitudinal feedbacks have been optimized for this more demanding mode of operation. Comparison between 100 and 50 bunches operation in 2002 runs is presented.