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Tomas, R.

Paper Title Page
MOPA007 Polarized Proton Collisions at RHIC 600
 
  • M. Bai, L. Ahrens, J.G. Alessi, J. Beebe-Wang, M. Blaskiewicz, A. Bravar, J.M. Brennan, D. Bruno, G. Bunce, J.J. Butler, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, W. Fischer, G. Ganetis, C.J. Gardner, J. Glenn, T. Hayes, H.-C. Hseuh, H. Huang, P. Ingrassia, U. Iriso, J.S. Laster, R.C. Lee, A.U. Luccio, Y. Luo, W.W. MacKay, Y. Makdisi, G.J. Marr, A. Marusic, G.T. McIntyre, R.J. Michnoff, C. Montag, J. Morris, T. Nicoletti, P. Oddo, B. Oerter, O. Osamu, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, K. Smith, S. Tepikian, R. Tomas, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, K. Vetter, M. Wilinski, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
    BNL, Upton, Long Island, New York
  • I.G. Alekseev, D. Svirida
    ITEP, Moscow
 
  Funding: The work was performed under the auspices of the U.S. Department of Energy and RIKEN Japan.

The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limited conditions are reported.

 
MPPE028 Non Linear Error Analysis from Orbit Measurements in SPS and RHIC 2012
 
  • J.F. Cardona
    UNAL, Bogota D.C
  • R. Tomas
    BNL, Upton, Long Island, New York
 
  Funding: U.S. Department of Energy and Colciencias.

Recently, an "action and phase" analysis of SPS orbits measurements proved to be sensitive to sextupole components intentionally activated at specific locations in the ring. In this paper we attempt to determine the strenght of such sextupoles from the measured orbits and compare them with the set values. Action and phase analysis of orbit trayectories generated by RHIC models with non linearities will also be presented and compare with RHIC experiments.

 
MPPE009 2003-2004 Nonlinear Optics Measurements and Modeling for the CERN SPS 1171
 
  • A. Faus-Golfe
    IFIC, Valencia
  • G. Arduini, F. Zimmermann
    CERN, Geneva
  • R. Tomas
    CELLS, Bellaterra (Cerdanyola del Vallès)
 
  In 2003 and 2004 nonlinear chromaticity, amplitude detuning, chromatic phase advance, resonance driving terms and off-energy orbits were measured in the CERN SPS at 14 GeV/c and 26 GeV/c, respectively. From the nonlinear chromaticity, the SPS optics model has been updated, by adjusting the strength of nonlinear field errors in dipoles and quadrupoles. Furthermore, we have added to the model the effect of the displacement of all main bends and the voluntary misalignments of all the other elements of the machine. We compare the field errors with those founded in 2002, 2001 and 2000. The tune shifts with transverse amplitude, driving terms, etc., predicted by this nonlinear optics model are compared with direct measurements.  
MPPE062 Measurement and Optimization of Local Coupling from RHIC BPM Data 3553
 
  • R. Calaga, S. Abeytunge, M. Bai, W. Fischer
    BNL, Upton, Long Island, New York
  • F. Franchi
    GSI, Darmstadt
  • R. Tomas
    CELLS, Bellaterra (Cerdanyola del Vallès)
 
  Funding: U.S. Department of Energy.

Global coupling in RHIC is routinely corrected by using three skew quadrupole families to minimize the tune split. In this paper we aim to re-optimize the coupling at top energy by minimizing resonance driving terms and the C-matrix in two steps: 1. Find the best configuration of the three skew quadrupole families and 2. Identify locations with coupling sources by inspection of the driving terms and the C-matrix around the ring. The measurements of resonance terms and C-matrix are presented.

 
TPAT093 Operations and Performance of RHIC as a Cu-Cu Collider 4281
 
  • F.C. Pilat, L. Ahrens, M. Bai, D.S. Barton, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, D. Bruno, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, W. Fischer, G. Ganetis, C.J. Gardner, J. Glenn, M. Harvey, T. Hayes, H.-C. Hseuh, H. Huang, P. Ingrassia, U. Iriso, R.C. Lee, V. Litvinenko, Y. Luo, W.W. MacKay, G.J. Marr, A. Marusic, R.J. Michnoff, C. Montag, J. Morris, T. Nicoletti, B. Oerter, V. Ptitsyn, T. Roser, T. Russo, J. Sandberg, T. Satogata, C. Schultheiss, S. Tepikian, R. Tomas, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, K. Vetter, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang
    BNL, Upton, Long Island, New York
 
  Funding: Work performed under the auspices of the U.S. Department of Energy.

The 5th year of RHIC operations, started in November 2004 and expected to last till June 2005, consists of a physics run with Cu-Cu collisions at 100 GeV/u followed by one with polarized protons at 100 GeV. We will address here overall performance of the RHIC complex used for the first time as a Cu-Cu collider, and compare it with previous operational experience with Au, PP and asymmetric d-Au collisions. We will also discuss operational improvements, such as a ?* squeeze to 85cm in the high luminosity interaction regions from the design value of 1m, system improvements and machine performance limitations, such as vacuum pressure rise, intra-beam scattering, and beam beam interaction.

 
TPAP048 Optimization of the Phase Advance Between RHIC Interaction Points 3031
 
  • R. Tomas
    CELLS, Bellaterra (Cerdanyola del Vallès)
  • W. Fischer
    BNL, Upton, Long Island, New York
 
  Funding: U.S. department of Energy.

We consider the scenario of having two identical Interaction Points (IPs) in the Relativistic Heavy Ion Collider (RHIC). The strengths of beam-beam resonances strongly depend on the phase advance between these two IPs and therefore certain phase advances could improve beam lifetime and luminosity. We compute the dynamic aperture as function of the phase advance between these IPs to find the optimum settings. The beam-beam interaction is treated in the weak-strong approximation and a complete non-linear model of the lattice is used. For the current RHIC proton working point (0.69,0.685) the design lattice is found to have the optimum phase advance. However this is not the case for other working points.

 
TPAT027 Measurement of Transverse Echoes in RHIC 1955
 
  • W. Fischer, T. Satogata
    BNL, Upton, Long Island, New York
  • R. Tomas
    CELLS, Bellaterra (Cerdanyola del Vallès)
 
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886.

Beam echoes are a very sensitive method to measure diffusion, and longitudinal echo measurements were performed in a number of machines. In RHIC, for the first time, a transverse beam echo was observed after applying a dipole kick followed by a quadrupole kick. After application of the dipole kick, the dipole moment decohered completely due to lattice nonlinearities. When a quadrupole kick is applied at time T after the dipole kick, the beam re-cohered at time 2T thus showing an echo response. We describe the experimental setup and measurement results. In the measurements the dipole and quadrupole kick amplitudes, amplitude dependent tune shift, and the time between dipole and quadrupole kick were varied. In addition, measurements were taken with gold bunches of different intensities. These should exhibit different transverse diffusion rates due to intra-beam scattering.