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Chao, Y.-C.

Paper Title Page
TPAP015 Commissioning of the LHC Beam Transfer Line TI 8 1461
 
  • J.A. Uythoven, G. Arduini, B. Goddard, D. Jacquet, V. Kain, M. Lamont, V. Mertens, A. Spinks, J. Wenninger
    CERN, Geneva
  • Y.-C. Chao
    Jefferson Lab, Newport News, Virginia
 
  The first of the two LHC transfer lines was commissioned in autumn 2004. Beam reached an absorber block located some 2.5 km downstream of the SPS extraction point at the first shot, without the need of any threading. The hardware preparation and commissioning phase will be summarised, followed by a description of the beam tests and their results regarding optics and other line parameters, including the experience gained with beam instrumentation, the control system and the machine protection equipment.  
TPAP018 Optics Studies of the LHC Beam Transfer Line TI8 1578
 
  • J. Wenninger, G. Arduini, B. Goddard, D. Jacquet, V. Kain, M. Lamont, V. Mertens, J.A. Uythoven
    CERN, Geneva
  • Y.-C. Chao
    Jefferson Lab, Newport News, Virginia
 
  The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectories, dispersion and profile measurements. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. Residual coupling between the planes was evaluated using high statistics samples of trajectories. Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors. The paper presents the various analysis methods and their errors. The expected emittance growth arising from optical mismatch into the LHC is evaluated.  
TPPP016 Beam Physics for the 12 GeV CEBAF Upgrade Project 1482
 
  • L. Merminga, J. F. Benesch, S.A. Bogacz, Y.-C. Chao, A. Freyberger, J.M. Grames, L. Harwood, R. Kazimi, G.A. Krafft, M. Spata, M. Tiefenback, M. Wiseman, B.C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
 
  Funding: Work supported by DOE Contract DE-AC05-84ER40150.

Beam physics aspects of the 12 GeV Upgrade of CEBAF are presented. The CEBAF Upgrade to 12 GeV is achieved via 5.5 recirculations through the linacs, and the installation of 10 new high-gradient cryomodules. A new experimental hall, Hall D, is envisioned at the end of North Linac. Simulation results for straight-through and recirculated injectors are summarized and compared. Beam transport designs are discussed and evaluated with respect to matching and beam breakup (BBU) optimization. Effects of synchrotron radiation excitation on the beam properties are calculated. BBU simulations and derived specifications for the damping of higher order modes of the new 7-cell cavities are presented. The energies that provide longitudinal polarization in multiple experimental halls simultaneously are calculated. Finally, a detailed optics design for the Hall D transport line has been obtained.

 
WPAP046 Injection Options for 12 GeV CEBAF Upgrade 2911
 
  • R. Kazimi, J. F. Benesch, Y.-C. Chao, J.M. Grames, G.A. Krafft, M. Tiefenback, B.C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
 
  Funding: Work supported by DOE Contract DE-AC05-84ER40150.

Jefferson Lab is planning to upgrade the CEBAF accelerator from 6 to 12 GeV. In order to achieve this, the beam energy at injection into the main accelerator needs to increase from 67 MeV to either 123 or 134 MeV depending on the location of the new experimental hall relative to the accelerator. The present 100 keV electron source and beam formation to 5 MeV will remain unchanged; however, the present accelerating cryomodules in the injector cannot reach the higher injection energies. Consequently, two options for attaining these energies are considered: (1) replacing the present injector cryomodules with new, higher gradient cryomodules, or (2) re-circulating the beam through the existing cryomodules to achieve the necessary energy gain in two passes. In this paper we present simulation results and list the advantages and disadvantages of these two options.