Paper | Title | Page |
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WEZA01 | Round Beam Collisions at VEPP-2000* | 1926 |
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The idea of round beams collision was proposed more than 20 years ago for the Novosibirsk Phi-factory design. It requires equal emittances, equal small fractional tunes, equal beta functions at the IP, no betatron coupling in the collider arcs. A 90° rotation at each passage of the transverse oscillation plane by means of solenoids in the interaction regions provides conservation of the longitudinal component of the angular moment. Thus the transverse motion becomes one-dimensional. Such a scheme helps to eliminate all betatron coupling resonances that are of crucial importance for beam-beam tune shift saturation and lifetime degradation. Only recently, the round beam concept was successfully tested at the electron-positron collider VEPP2000 at the energy of 510 MeV. Despite the low energy a high single bunch luminosity of 1031 cm-2s−1 was achieved together with a maximum tune shift as high as 0.1. At present the work is in progress to increase the energy of the collider to explore the range between 510 MeV and 1 GeV in collision. | ||
Slides WEZA01 [3.740 MB] | ||
WEZA02 | Colliders for B Factories | 1931 |
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Two new B factories, SuperB in Frascati and SuperKEKB in Tsukuba, aim at unprecedented luminosities close to 1036/cm2/s. The designs, status, challenges, and differences between the two machines are reported. Emphasis should be put on recent developments for the B factories. The presentation should include a realistic outlook. | ||
Slides WEZA02 [6.796 MB] | ||
THPZ001 | Spin Dynamic Tool Developments and Study Regarding the Super-B Project | 3681 |
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The study of polarization is essential for e+/e- colliders like the SuperB machine. The ZGOUBI integrator is a good and universal tool for particle tracking as well as spin tracking, and takes into account all machine realistic aspects, like real fields, non-linearities, fringing fields or misalignments. We present ZGOUBI implementation and the methods carried out to estimate invariant spin field and beam polarization evolution on some simple models (for validation) and on SuperB, and we investigate for some specific polarization behavior. | ||
THPZ003 | The SuperB Project: Accelerator Status and R&D | 3684 |
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The SuperB collider project has been recently approved by the Italian Government as part of the National Research Plan. SuperB is a high luminosity (1036 cm-2 s-1) asymmetric e+e− collider at the Y(4S) energy. The design is based on a “large Piwinski angle and Crab Waist” scheme already successfully tested at the DAΦNE Phi-Factory in Frascati, Italy. The project combines the challenges of high luminosity colliders and state-of-the-art synchrotron light sources, with two beams (e+ at 6.7 and e- at 4.2 GeV) with extremely low emittances and small beam sizes at the Interaction Point. As unique features, the electron beam will be longitudinally polarized at the IP and the rings will be able to ramp down to collide at the tau/charm energy threshold with one tenth the luminosity. The relatively low beam currents (about 2 A) will allow for low running (power) costs compared to similar machines. The insertion of beam lines for synchrotron radiation users is the latest feature included in the design. The lattice has been recently modified to accommodate insertion devices for X-rays production. A status of the project and a description of R&D in progress will be presented. | ||
THPZ004 | DAΦNE Tune-up for the KLOE-2 Experiment | 3687 |
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Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11). In its continuous evolution DAΦNE, the Frascati lepton collider, is starting a new run for the KLOE-2 experiment, an upgraded version of the KLOE one. A new interaction region, based on the high luminosity Crab-Waist collision scheme, has been designed, built and installed. Several machine subsystems have been revised according to innovative design concepts in order to improve beam dynamics. Collimators and shieldings have been upgraded in order to minimize the background rates on the detector during coasting as well as injection operation. A wide measurement campaign has been undertaken to verify and quantify the effect of the modifications and to tune-up the collider in view of the 3 years long data-taking foreseen to deliver ~5 fb-1 to the experiment. |
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THPZ006 | SuperKEKB Interaction Region Modeling | 3690 |
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In the SuperKEKB interaction region(IR) design, the beam-line intersects solenoid-axis with large angle and the superconducting final focusing quadrupole magnets are installed into each beam-lines without iron-shield. Because of these features, the emittance and dynamic aperture evaluation have to consider the solenoid fringe field and the leakage multipole field of another beam-line magnet, respectively. The IR lattice modeling and the magnetic field handling of both solenoid and multipole field would be reported in this article. | ||
THPZ008 | Strong-strong Simulations for Super B Factories II | 3696 |
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Trials for the strong-strong simulation for study of beam-beam effect in large Piwinski angle (LPA) collision adopted in Super B factories. So far a combination method of particle in cell method and soft-Gaussian model has been used. We now show complete strong-strong simulation for LPA collision scheme. Collisions between many slices of two bunches are evaluated by particle in cell method with shifted Green function. | ||
THPZ009 | Beam Background Simulation for SuperKEKB/Belle-II | 3699 |
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The Belle experiment is now being upgraded to the Belle II experiment designed for a 40 times higher luminosity. Such a high luminosity is realized by the SuperKEKB collider where beam-induced background rates are expected to be much higher than those of KEKB. This poses a serious challenge for the design of the machine-detector interface. We have thus carried out a GEANT4-based beam background simulation for Touschek effect. We describe the method of generating background particles and present the result of simulation. | ||
THPZ010 | Beam Background and MDI Design for SuperKEKB/Belle-II | 3702 |
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The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x1035 cm-2s-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc. | ||
THPZ011 | Optimization of Chromatic Sextupoles in Electron Storage Rings Using Genetic Algorithms | 3705 |
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Funding: Work supported by National Science Foundation of China contract 10725525. In order to suppress the head-tail instability, strong chromatic sextupoles are used in modern electron storage rings to correct large chromaticities due to small emittance or strong insertion quadrupoles to squeeze the bunch size at some places. However, the introduction of strong chromatic sextupoles also brings severe nonlinearity and might reduce dynamic aperture drastically. In the case of several sextupole families, the genetic algorithms are applied to find suitable configurations of sextupole strengths, directly maximizing dynamic aperture. A GeneRepair operator is introduced into the algorithm to correct chromaticities and optimize the dynamic aperture simultaneously in electron storage rings. |
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THPZ012 | Luminosity Enhancement and Performance in BEPCII | 3708 |
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The Beijing Electron Positron Collider (BEPC) was upgraded to a factory-like machine –- BEPCII, during last several years. From last November, the BEPCII was commissioned again for its luminosity. Efforts on optics correction including optimizing the strengths of superconducting quadrupoles near the IP, orbits correction concerning beam energy, etc, make the transvers tunes possible to move very close to half integer, bringing a big luminosity increase. The background of the detector is also reduced with beam commissioning, and finally fit the requirements of data taking. Further luminosity commissioing, including coupling optimization, beta-waist tuning, was carried on, and the luminosity reached 6.49·1032 cm-2 s-1 during routine operation. Some measures of luminosity enhancement and the luminosity related accelerator physics issues will be discussed. | ||