Paper | Title | Page |
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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. | ||
THPZ007 | Lattice Design of Low Emittance and Low Beta Function at Collision Point for SuperKEKB | 3693 |
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Extremely low beta function at the interaction point(IP) and low emittance are necessary to achieve the design luminosity of 8x1035 cm-2 s-1 for a SuperKEKB project. The low emittance with a large Piwinski angle makes this possible with longer bunch longitudinally compared with the vertical beta function at IP. We call this Nano-beam scheme. In this scheme, a beam-beam parameter is realized to be less than 0.09 for the design luminosity. The lattice features, chromaticity corrections, and dynamic aperture are discussed 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. | ||
THPZ013 | A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities | 3711 |
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The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme*.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings. |
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THPZ014 | LHeC Lattice Design | 3714 |
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The Large Hadron Electron Collider (LHeC) aims at lepton-proton and lepton-nucleus collisions with centre of mass energies of 1-2 TeV at ep luminosities in excess of 1033 cm-2 s-1. We present here a lattice design for the electron ring option, which meets the design parameters and also the constraints imposed by the integration of the new electron ring in the LHC tunnel. | ||
THPZ015 | Synchrotron Radiation in the Interaction Region for a Ring-Ring and Linac-Ring LHeC | 3717 |
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The Large Hadron electron Collider (LHeC) aims at bringing hadron-lepton collisions to CERN with center of mass energies in the TeV scale. The LHeC will utilize the existing LHC storage ring with the addition of a 60 GeV electron accelerator. The electron beam will be stored and accelerated in either a storage ring in the LHC tunnel (Ring-Ring) or a linac tangent to the LHC tunnel (Linac-Ring). Synchrotron Radiation (SR) in the Interaction Region (IR) of this machine requires an iterative design process in which luminosity is optimized while the SR is minimized. This process also requires attention to be given to the detector as the beam pipe must be designed such that damaging effects, such as out-gasing, are minimized while the tracking remains close to the IP. The machinery of GEANT4 has been used to simulate the SR load in the IR and also to design absorbers/masks to shield SR from backscattering into the detector or propagating with the electron beam. The outcome of these simulations, as well as cross checks, are described in the accompanying poster which characterizes the current status of the IR design for both the Ring-Ring and Linac-Ring options of the LHeC in terms of SR. | ||
THPZ016 | Interaction Region Design for a Ring-Ring LHeC | 3720 |
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The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. Using one of the LHC's proton beams, an electron beam of relatively low energy and moderately high intensity provides high luminosity TeV-scale e-p collisions at one of the LHC interaction points, running simultaneously with existing experiments. Two designs are studied; an electron ring situated in the LHC tunnel, and an electron linac. The focus of this paper is on the ring design. Designing an e-p machine presents interesting accelerator physics and design challenges, particularly when considering the interaction region. These include coupled optics, beam separation and unconventional mini-beta focusing schemes. Designs are constrained by an array of interdependent factors, including beam-beam interaction, detector dimensions and acceptance, luminosity and synchrotron radiation. Methods of addressing these complex issues are discussed. The current designs for the LHeC Ring-Ring interaction region and long straight section are presented and discussed, in the context of the project goals and design challenges encountered. Future developments and work are also discussed. | ||
THPZ017 | Achromatic Low-beta Interaction Region Design for an Electron-ion Collider | 3723 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by Muons, Inc. An achromatic Interaction Region (IR) design concept is presented with an emphasis on its application at an electron-ion collider. A specially-designed symmetric Chromaticity Compensation Block (CCB) induces an angle spread in the passing beam such that it cancels the chromatic kick of the final focusing quadrupoles. Two such CCB’s placed symmetrically around an interaction point (IP) allow simultaneous compensation of the 1st-order chromaticities and chromatic beam smear at the IP without inducing significant 2nd-order aberrations. Special attention is paid to the difference in the electron and ion IR design requirements. We discuss geometric matching of the electron and ion IR footprints. We investigate limitations on the momentum acceptance in this IR design. |
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THPZ019 | High Luminosity Electron-hadron Collider eRHIC | 3726 |
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We present the design of a future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan adding 20 (30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 1034 cm-2s−1 can be achieved in eRHIC using the low-beta interaction region which a 10 mrad crab crossing. A natural staging scenario of step-by-step increases of the electron beam energy by builiding-up of eRHIC's SRF linacs. We report on the eRHIC design and cost estimates for it stages. We discuss the progress of eRHC R&D projects from the polarized electron source to the coherent electron cooling. | ||
THPZ020 | eRHIC Interaction Region Design | 3729 |
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Funding: *Work performed under a Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy. Interaction region design of the future electron ion collider at Relativistic Heavy Ion Collider (eRHIC) is presented. Polarized protons/Helium and heavy ions will collider with 5-30 GeV polarized electrons with a 10 mrad angle by using the crab cavity crossing. The interaction region is designed without bending electrons to avoid problems with synchrotron radiation. Use of the combined function magnet in the ion side allows detection of neutrons. Design allows detection of deep virtual scattering as well as detection of partons with lower energies (po/2.5). The betatron function at collisions is 5 cm assuming use of three dimensional electron beam cooling. Special chromaticity correction is applied in both sides of the ion straight section interaction region. Electrons arrive with avoiding completely synchrotron radiation at the detector. Special superconducting combined function magnet is designed to allow passage of electrons through the field free region. |
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THPZ021 | Effect of Coherent Synchrotron Radiation at the SuperKEKB Damping Ring | 3732 |
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The longitudinal wake field dominated by the CSR is important at the SuperKEKB damping ring. The peak of the CSR wake field is 100 times higher than those of the vacuum chamber components. We calculated the CSR effect for different vacuum chamber cross-sections, and adopted one which reduced longitudinal instability. | ||
THPZ022 | Operation Scheme and Statistics of KEKB | 3735 |
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The KEKB B-Factory(KEKB) started a collision experiment in 1999 and finished in June, 2010. The total operation time of KEKB from fiscal year 2000 was 55657 hours. The breakdowns of operation are physics run 73.8%, machine study 6.8%, machine tuning 4.8%, beam tuning 5.9%, trouble 5.3%, maintenance 2.1% and other 1.3%. The total integrated luminosity was 1041 fb-1 and the maximum peak luminosity was 21.083 nb-1s−1. To increase the peak and integrated luminosity, the continuous injection scheme, the crab cavities and the skew sextupole magnets were effective. We finished over ten year operation of KEKB in June, 2010. | ||
THPZ024 | Updated Design of the Italian SuperB Factory Injection System | 3738 |
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The ultra high luminosity B-factory (SuperB) project of INFN requires a high performance and reliable injection system, providing electrons at 4 GeV and positrons at 7 GeV, to fulfill the very tight requirements of the collider. Due to the short beam lifetime, continuous injection of electrons and positrons in both HER and LER rings is necessary to keep the average luminosity at a high level. An updated version of the injection system, optimized at higher repetition frequency is presented. This scheme includes a polarized electron gun, a positron production scheme with electron/positron conversion at low energy 0.6 GeV, and a 1 GeV damping ring to reduce the injected emittance of the positron beam. | ||
THPZ025 | Stability of the LHC Transfer lines | 3741 |
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The LHC is filled from the SPS through two 3 km transfer lines. The injected beam parameters need to be well under control for luminosity performance, machine protection and operational efficiency. Small fractions of beam loss on the transfer line collimation system create showers which can trigger the sensitive LHC beam loss monitor system nearby and cause a beam abort during filling. The stability of the transfer line trajectory through the collimators is particularly critical in this respect. This paper will report on the transfer line trajectory stability during the proton run in 2011, correlations with injection losses, correction frequency and the most likely sources for the observed oscillations. | ||
THPZ026 | Collimation Dependent Beam Lifetime and Loss Rates in the LHC | 3744 |
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The four primary collimators in each LHC beam define the smallest aperture. Particles with high betatron amplitudes or momentum offset will therefore hit first a primary collimator. The instantaneous particle loss rate at primary collimators is an important measure for the global lifetime of the beams and a major ingredient to identify collimation induced performance limitations in the LHC. These loss rates have been measured during a number of LHC fills, featuring both "good" fills with high luminosity and "bad" fills with beam instabilities. The beam lifetime at the collimators was then calculated from this data for different cases. The results are presented and interpreted within this paper. | ||
THPZ027 | First Beam Results for a Collimator with In-jaw Beam Position Monitors | 3747 |
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With more than 100 collimators the LHC has the most complex collimation system ever installed in an accelerator. The beam-based setup time of the system was a non-negligible factor during the commissioning of the LHC. In addition if the particle orbit at a collimator goes out of tolerance, this collimator needs to be setup again. To reduce the required setup time for the collimation system and to obtain the tight tolerances required for the LHC operation with small beta* and high beam energy, a new collimator design is being developed that integrates a beam position monitor (BPM) into the jaws of the collimator. A prototype of such a phase-II LHC collimator was installed in the SPS at CERN for the 2010 run. In this paper we present the first experimental results from the beam tests performed. | ||
THPZ028 | Upgrade Studies for the LHC Collimators | 3750 |
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The Phase-I LHC Collimation System has to be upgraded to work at high intensity and energy. Theoretical and engineering studies are focusing on different regions of the machine. The IR3 combined momentum and betatron cleaning, initially approved for installation, has presently been kept as fallback solution in case radiation to equipment limits LHC performance. The installation of collimators in the dispersion suppressor section DS3 has been delayed. In this paper we present predictions with matched optics and the effect of machine imperfections on the collimation performance with IR3 combined cleaning, with and without DS3 collimators. | ||
THPZ029 | Principles for Generation of Time-dependent Collimator Settings during the LHC Cycle | 3753 |
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The settings of the LHC collimators have to be changed during the cycle of injection, ramp and squeeze to account for variations in the orbit, beam size and normalized distance to the beam center. We discuss the principles for how the settings are calculated and show a software tool that computes them as time-dependent functions from beam-based data and theoretical optics models. | ||
THPZ030 | Halo Scrapings with Collimators in the LHC | 3756 |
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The population of the beam halo has been measured in the LHC with beam scraping experiments. Primary collimators of the LHC collimation system were used to scrape the beam halo at different statuses of the machine (injection, top energy, separated and colliding beams). In addition these measurements were used to calibrate the beam loss monitor signals to loss rates at the primary collimators. Within this paper the halo scraping method, the measured halo distribution and the calibration factors are presented and compared to theoretical predictions. | ||
THPZ031 | Acoustic Measurements in the Collimation Region of the LHC | 3759 |
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The LHC accelerator at CERN has the most advanced collimation system ever being installed. The collimators intercept unavoidable particle losses and therefore are essential to avoid beam induced quenches of the superconducting magnets. In addition, they provide passive machine protection against mis-kicked beams. During material robustness tests on a LHC collimator prototype in 2004 and 2006, vibration and acoustic measurements have shown that a beam impact detection system should be feasible using accelerometers and microphones as sensors in the LHC. Recently, such sensors have been installed close to the primary collimators in the LHC tunnel. First analyses of raw data show that the system is sensitive enough to detect beam scraping on collimators. Therefore, the implementation of a sophisticated acoustic monitoring system is under investigation. It may be useful not only to detect beam impacts on primary collimators in case of failure, but also to derive further information on beam losses that occur during regular operation. This paper gives an overview on the recent installation, results of the acoustic measurements made at the LHC, and future plans. | ||
THPZ032 | Evaluation of the Combined Betatron and Momentum Cleaning in Point 3 in Terms of Cleaning Efficiency and Energy Deposition for the LHC Collimation Upgrade | 3762 |
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Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. The Phase I LHC Collimation System Upgrade could include moving part of the Betatron Cleaning from LHC Point 7 to Point 3 to improve both operation flexibility and intensity reach. In addition, the partial relocation of beam losses from the current Betatron cleaning region at Point 7 will mitigate the risks of Single Event Upsets to equipment installed in adjacent and partly not adequate shielded areas. A combined Betatron and Momentum Cleaning scenario at Point 3 implies the installation of new collimators and a new collimator aperture layout. This paper shows the whole LHC Collimator Efficiency variation with the new layout proposed at different beam energies. As part of the evaluation, energy deposition distribution in the IR3 region gives indications about the effect of this new implementation not only on the collimators themselves but also on the other beam line elements. |
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THPZ033 | Operational Experience and Performance of the LHC Collimator Controls System | 3765 |
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In order to handle stored energies up to 360 MJ, the LHC relies on a collimation system that consists of 100 movable collimators. Compared to other accelerator, the complexity of this system is unique: more than 400 motors and about 600 interlocked position sensors must be controlled in all the machine phases in order to ensure the cleaning and machine protection roles of the system. In this paper, the controls system and the setting management are presented and the operational experience accumulated in the 2 first years of operation is discussed, focussing in particular on failure and availability statistics during the LHC operation. | ||
THPZ034 | Semi-automatic Beam-based Alignment Algorithm for the LHC Collimation System | 3768 |
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Full beam-based alignment of the LHC collimation system was a lengthy procedure as the collimators were set up manually. A yearly alignment campaign has been sufficient for now, although in future this may lead to a decrease in the cleaning efficiency if machine parameters such as the beam orbit drift over time. Automating the collimator setup procedure can allow for more frequent alignments, therefore reducing this risk. This paper describes the design and testing of a semi-automatic algorithm as a first step towards a fully automatic setup. Its implementation in the collimator control software and future plans are described. | ||
THPZ035 | Comparison of LHC Collimation Setups with Manual and Semi-automatic Collimator Alignment | 3771 |
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The LHC collimation system beam-based alignment procedure has recently been upgraded to a semi-automatic process in order to increase its efficiency. In this paper, we describe the parameters used to measure the accuracy, stability and performance of the beam-based alignment of the LHC collimation system. This is followed by a comparison of the results at 450 GeV and 3.5 TeV with (1) a manual alignment and (2) with the results for semi-automatic alignment. | ||