A. Morita

Recent Progress at KEKB

We summarize the machine operation of KEKB during past one year focusing on progress for this period.

Lattice Upgrade Plan for Crab Crossing at the KEKB Rings

We plan to install two superconducting crab cavities into the rings at January, 2006. In our plan, we will install one crab cavity per one ring into the NIKKO straight section where the cryogenic infrastructure is already operated for the superconducting accelerating cavities. For crab crossing, we have to enlarge the horizontal beta function(200m for HER) and have to adjust the horizontal phase advance between the interaction point and the crab cavity. In this paper, we will report the lattice modified for the crab crossing and the study results about the single beam dynamics.

Global-Beta Measurement and Correction at the KEKB Rings

The global-beta correction is one of the optics corrections such as dispersion and xy-coupling corrections to realize a model lattice [1]. In the KEKB B-Factory, it is performed to regularize the ring optics for achieving high luminosity. The global-beta function is measured by re-constructing responses of orbits generated by 6 different steering magnets per plane. The correction of the beta function and the phase advance is performed by using the fudge factors of power supplies of quadrupole magnets. This correction scheme has been successfully. In the typical case, the rms of the beta function beat and the betatron tune difference are corrected within 5% and 0.0005, respectively. In the luminosity run, we can operate the low energy ring(LER) with the horizontal betatron tune very close to half-integer(45.5050). In this paper, we will report in detail the measurement and correction techniques and its performance in the KEKB operation.

Commissioning of the Phase-I SuperKEKB B-Factory and Update on the Overall Status

The SuperKEKB B-Factory at KEK (Japan), after few years of shutdown for the construction and renovation, has finally come to the Phase-1 commissioning of the LER and HER rings, without the final focus system and the Belle II detector. Vacuum scrubbing, optics tuning and beam related background measurements were performed in this phase. Low emittance tuning techniques have also been applied in order to set up the rings for Phase-2 with colliding beams next year. An update of the final focus system construction, as well as the status of the injection system with the new positron damping ring and high current/low emittance electron gun is also presented.

Recent progress of optics correction at KEKB

Chromaticity correction is a part of optics corrections, which takes an important role to control both the dynamic aperture and the strength of synchro-beta resonance. Whenever the linear optics is changed to control the emittance, etc, the chromaticity correction i.e. sextupole settings must be re-optimized. In this paper, we present new method to find chromaticity correction parameters to maximize the dynamic aperture and minimize the synchro-beta resonance.

Beam-beam effects observed at KEKB

At KEKB, a dedicated machine experiment on crab crossing has been carried out for about 4.5 months. Some of the beam-beam effects observed with crab crossing, which include a beam lifetime issue, are discussed in comparison with those with a finite crossing angle of plusmn11 mrad.