• Z.G. Zong, N. Higashi, N. Ohuchi, M. Tawada, K. Tsuchiya
  KEK, Ibaraki

To supply the electrical power for the superconducting correctors in the interaction region of the proposed SuperKEKB, a kind of vapor cooled current leads is designed, which consists of 8 brass leads and can transport currents to 4 correctors simultaneously. The design current of the leads is about 50 A. The thermal and electrical behaviors have studied by the finite elements method and the cryogenic experiment is also planed to validate the performance. In this paper the design will be presented and the finite element model will be compared with the experimental data.

• A.V. Zlobin, V. Kashikhin, N.V. Mokhov, I. Novitski
  Fermilab, Batavia

Magnetic and mechanical designs of a superconducting quadrupole magnet with 120-mm aperture suitable for interaction regions of hadron colliders are presented. The magnet is based on a two-layer shell-type coil and a cold iron yoke. Special spacers made of a low-Z material are implemented in the coil midplanes to reduce the level of radiation heat deposition in the coil. The quadrupole mechanical structure is based on a thick aluminum collar supported by the iron yoke and stainless steel skin. Magnet parameters including maximum field gradient, field quality and temperature margin for NbTi or Nb₃Sn coils at the operating temperatures of 1.9 K and 4.5 K are reported. The level and distribution of radiation heat deposition in the coil and other magnet components are discussed.

• S.M. White, R. Alemany-Fernandez, H. Burkhardt, M. Lamont
  CERN, Geneva

Once circulating beams have been established in the LHC the first step towards collisions is to remove the physical separation used to avoid collisions during injection and ramp. A residual separation can remain after the collapsing of the separation bumps. The so-called Van Der Meer method allows for a minimization of this unwanted separation by transversally scanning one beam through the other. The beam sizes at the IP can also be determined by this method and used to give an absolute measurement of the luminosity. We report on how this measurement was implemented and performed in the LHC to optimize and calibrate luminosity.

• J. Stiller
  Heidelberg University, Heidelberg
• H.S. Matis, A. Ratti, W.C. Turner
  LBNL, Berkeley, California
• R. Miyamoto
  BNL, Upton, Long Island, New York
• S.M. White
  CERN, Geneva

The LHC BRAN luminosity detector monitors the high luminosity interaction regions (Atlas and CMS). This chamber, which is an Argon gas ionization detector measures the forward neutral particles from collisions the interaction region. To predict and improve the understanding of the detector's performance, we produced a detailed model of the detector and its surroundings in FLUKA. In this paper, we present the model and results of our simulations including the detector's estimated response to interactions for beam energies of 3.5, 5.0, and 7.0 TeV.

• R. Calaga, W. Fischer, G. Robert-Demolaize
  BNL, Upton, Long Island, New York

Long range beam-beam experiments were conducted during the Run 2009 in the yellow and the blue beams of the RHIC accelerator with DC wires. The effects of a long-range interaction with a DC wire on colliding and non-colliding bunches with the aid of orbits, tunes, and losses were studied. Results from distance and currents scans and an attempt to compensate a long-range interaction with a DC wire is presented.

• P. Thieberger, R. Bonati, G.F. Corbin, J.P. Cozzolino, A.K. Jain, G.T. McIntyre, M.G. Minty, C. Montag, J.F. Muratore, C. Schultheiss, S. Seberg, J.E. Tuozzolo
  BNL, Upton, Long Island, New York

We report on recent developments for mitigating vibrations of the quadrupole magnets near the interaction regions of the Relativistic Heavy Ion Collider (RHIC). High precision accelerometers, geophones, and a laser vibrometer were installed around one of the two interaction points to characterize the frequencies of the mechanical motion. In addition actuators were mounted directly on the quadrupole cryostats. Using as input the locally measured motion, dynamic damping of the mechanical vibrations has been demonstrated. In this report we present these measurements and measurements of the beam response. Future options for compensating the vibrations are discussed.

• K. Ohmi, H. Koiso
  KEK, Ibaraki

Progress of Graphic Processor Unit (GPU) is marveled. The performance is 1TFlops per unit. Simulation of electron gun can be performed by particle-particle interactions, in which the calculation cost is NxN. Since the calculation of each interaction is very simple, GPU can demonstrate its ability. We show simulation results and discuss the possibilities to extend other simulations.

• K.J. Bertsche, M.K. Sullivan
  SLAC, Menlo Park, California

We present an approach for compensating adverse effects of the detector solenoid in the SuperB Interaction Region (IR). We place compensating solenoids around the IR quadrupole magnets to reduce the magnetic fields nearly to zero. This allows more operational headroom for superconducting IR magnets and avoids saturation of ferric IR magnets. We place stronger compensating solenoids between IR magnets to reverse the magnetic field direction. This allows adjusting the total integrated solenoid field to zero, which eliminates coordinate plane rotation and reduces vertical beam displacements in the IR.

• M.K. Sullivan, K.J. Bertsche
  SLAC, Menlo Park, California
• S. Bettoni
  CERN, Geneva
• E. Paoloni
  University of Pisa and INFN, Pisa
• P. Raimondi
  INFN/LNF, Frascati (Roma)
• P. Vobly
  BINP SB RAS, Novosibirsk

A final focus magnet design that uses super-ferric magnets is introduced for the Super-B interaction region. The baseline design has air-core super-conducting quadrupoles. This idea instead uses super-conducting wire in an iron yoke. The iron is in the shape of a Panofsky quadrupole and this allows for two quadrupoles to be side-by-side with no intervening iron as long as the gradients of the two quads are equal. This feature allows us to move in as close as possible to the collision point and minimize the beta functions in the interaction region. The super-ferric design has advantages as well as drawbacks and we will discuss these in the paper.

• S.P. Weathersby, A. Novokhatski
  SLAC, Menlo Park, California

The geometry of storage ring collider interaction regions present an impedance to beam fields resulting in the generation of additional electromagnetic fields (higher order modes or wake fields) which affect the beam energy and trajectory. These affects are computed for the Super B interaction region by evaluating longitudinal loss factors and averaged transverse kicks for short range wake fields. Results indicate at least a factor of 2 lower wake field power generation in comparison with the interaction region geometry of the PEP-II B-factory collider. Wake field reduction is a consideration in the Super B design. Transverse kicks are consistent with an attractive potential from the crotch nearest the beam trajectory. The longitudinal loss factor scales as the -2.5 power of the bunch length. A factor of 60 loss factor reduction is possible with crotch geometry based on an intersecting tubes model.

• Y.S. Tan
  Lancaster University, Lancaster
• R. Seviour
  Cockcroft Institute, Lancaster University, Lancaster

In this paper we examine the effect of introducing an Electromagnetic metamaterial into a Travelling Wave structure to mediate inverse Cherenkov acceleration. Electromagnetic metamaterials are artificial materials that consist of macroscopic structures that yield an effective permittivity and permeability less than zero. The properties of metamaterials are highly frequency dependent and give rise to very novel dispersion relationships. We show that the introduction of a specifically designed metamaterial into the interaction region gives rise to a novel dispersion curve yielding a unique wave-particle interaction. We demonstrate that this novel wave-particle interaction gives rise energy exchange from wave to beam over an extended interaction regime. We also discuss the benefits and issues that arise from having a metamaterial in a high vacuum high power environment with a specific focus on the issue of loss in metamaterial structures.