MOODN —  Colliders II   (28-Mar-11   16:00—17:30)
Chair: B.P. Strauss, DOE, Washington, USA
Paper Title Page
MOODN1 Results of Head-on Beam-beam Compensation Studies at the Tevatron 67
 
  • A. Valishev, G. Stancari
    Fermilab, Batavia, USA
 
  Funding: Work supported by the Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the United States Department of Energy, and by the DOE through the US LHC Accelerator Research Program (LARP).
At the Tevatron collider, we studied the feasibility of suppressing the antiproton head-on beam-beam tune spread using a magnetically confined 5-keV electron beam with Gaussian transverse profile overlapping with the circulating beam. When electron cooling of antiprotons is applied in regular Tevatron operations, the head-on beam-beam effect on antiprotons is small. Therefore, we first focused on the operational aspects, such as beam alignment and stability, and on fundamental observations of tune shifts, tune spreads, lifetimes, and emittances. We also attempted two special collider stores with only 3 proton bunches colliding with 3 antiproton bunches, to suppress long-range forces and enhance head-on effects. We present here the results of this study and a comparison between numerical simulations and observations, in view of the planned application of this compensation concept to RHIC.
 
slides icon Slides MOODN1 [2.680 MB]  
 
MOODN2 Optimizing the Electron Beam Parameters for Head-on Beam-beam Compensation in RHIC 70
 
  • Y. Luo, W. Fischer, X. Gu, A.I. Pikin
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Head-on beam-beam compensation is adopted to compensate the large beam-beam tune spread from the proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). Two e-lenses are being built and to be in stalled near IP10 in the end of 2011. In this article we perform numeric simulation to investigate the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse profile, size, current, offset and random errors in them.
 
slides icon Slides MOODN2 [0.601 MB]  
 
MOODN3 Advanced Bent Crystal Collimation Studies at the Tevatron (T-980) 73
 
  • V.V. Zvoda, J. Annala, R.A. Carrigan, A.I. Drozhdin, T.R. Johnson, S. Kwan, N.V. Mokhov, A. Prosser, R.E. Reilly, R. Rivera, V.D. Shiltsev, D.A. Still, L. Uplegger, J.R. Zagel
    Fermilab, Batavia, USA
  • E. Bagli, V. Guidi, A. Mazzolari
    INFN-Ferrara, Ferrara, Italy
  • Y.A. Chesnokov, I.A. Yazynin
    IHEP Protvino, Protvino, Moscow Region, Russia
  • Yu.M. Ivanov
    PNPI, Gatchina, Leningrad District, Russia
 
  Funding: * Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy through the US LHC Accelerator Research Program (LARP).
The T-980 bent crystal collimation experiment at the Tevatron has recently acquired substantial enhancements. First, two new crystals - a 16-strip one manufactured and characterized by the INFN Ferrara group and a quasi-mosaic crystal manufactured and characterized by the PNPI group. Second, a two plane telescope with 3 high-resolution pixel detectors per plane along with corresponding mechanics, electronics, control and software has been manufactured, tested and installed in the E0 crystal region. The purpose of the pixel telescope is to measure and image channeled (CH), volume-reflected (VR) and multiple volume-reflected (MVR) beam profiles produced by bent crystals. Third, an ORIGIN-based system has been developed for thorough analysis of experimental and simulation data. Results of analysis are presented for different types of crystals used from 2005 to present for channeling and volume reflection including pioneering tests of two-plane crystal collimation at the collider, all in comparison with detailed simulations.
 
slides icon Slides MOODN3 [1.052 MB]  
 
MOODN4 Beam Losses Due to Abrupt Crab Cavity Failures in the LHC 76
 
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  • T. Baer, J. Barranco, R. Tomás, J. Wenninger, F. Zimmermann
    CERN, Geneva, Switzerland
  • B. Yee-Rendon
    CINVESTAV, Mérida, Mexico
 
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
A major concern for the implementation of crab crossing in a future high-luminosity LHC (HL-LHC) is machine protection in an event of a fast crab-cavity failure. Certain types of abrupt crab-cavity phase and amplitude changes are simulated to characterize the effect of failures on the beam and the resulting particle-loss signatures. The time-dependent beam loss distributions around the ring and particle trajectories obtained from the simulations allow for a first assessment of the resulting beam impact on LHC collimators and on sensitive components around the ring. The simulation results are used to derive tolerances on the maximum rate of change in crab-cavity phase and amplitude which can be allowed with regard to machine safety.
 
slides icon Slides MOODN4 [1.620 MB]  
 
MOODN5 Chromaticity Correction for a Muon Collider Optics 79
 
  • E. Gianfelice-Wendt, Y. Alexahin, V.V. Kapin
    Fermilab, Batavia, USA
 
  Funding: Work supported by Fermi Research Alliance, LLC under DE-AC02-07CH11359 with the U.S. DOE
Muon Collider (MC) is a promising candidate for the next energy frontier machine. However, in order to obtain peak luminosity in the 1034cm-2s-1 range the collider lattice design must satisfy a number of stringent requirements. In particular the expected large momentum spread of the muon beam and the very small β* call for a careful correction of the chromatic effects. Here we present a particular solution for the interaction region (IR) optics whose distinctive feature is a three-sextupole local chromatic correction scheme. The scheme may be applied to other future machines where chromatic effects are expected to be large.
 
slides icon Slides MOODN5 [0.554 MB]  
 
MOODN6 Muon Collider Interaction Region and Machine-detector Interface Design 82
 
  • N.V. Mokhov, Y. Alexahin, V. Kashikhin, S.I. Striganov, A.V. Zlobin
    Fermilab, Batavia, USA
 
  Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
One of the key systems of a Muon Collider (MC)- seen as the most exciting options for the energy frontier machine in the post-LHC era - is its interaction region (IR). Designs of its optics, magnets and machine-detector interface are strongly interlaced and iterative. As a result of recent comprehensive studies, consistent solutions for the 1.5 TeV c.o.m. MC IR have been found and are described here. To provide the required momentum acceptance, dynamic aperture and chromaticity, innovative approach was used for the IR optics. Conceptual designs of large-aperture high-field dipole and high-gradient quadrupole magnets based on Nb3Sn superconductor were developed and analyzed in terms of the operation margin, field quality, mechanics, coil cooling and quench protection. Shadow masks in the interconnect regions and liners inside the magnets are used to mitigate unprecedented dynamic heat deposition due to muon decays (~1 kW/m). It is shown that an appropriately designed machine-detector interface with sophisticated shielding in the detector has a potential to substantially suppress the background rates in the MC detector.
 
slides icon Slides MOODN6 [1.233 MB]