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Luo, Y.

Paper Title Page
MOPA009 Global Decoupling on the RHIC Ramp 659
 
  • Y. Luo, P. Cameron, A. Della Penna, W. Fischer, J.S. Laster, A. Marusic, F.C. Pilat, T. Roser, D. Trbojevic
    BNL, Upton, Long Island, New York
 
  Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886.

The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). In the polarized proton run, the betatron tunes are required to keep almost constant on the ramp to avoid spin resonance line crossing and the beam polarization loss. Some possible correction schemes on the ramp, like three-ramp correction, the coupling amplitude modulation and the coupling phase modulaxtion, have been found. The principles of these schemes are shortly reviewed and compared. Operational results of their applications on the RHIC ramps are given.

 
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.

 
MPPE030 Comparison of Off-Line IR Bump and Action-Angle Kick Minimization 2116
 
  • Y. Luo, F.C. Pilat, V. Ptitsyn, D. Trbojevic, J. Wei
    BNL, Upton, Long Island, New York
 
  Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886.

The interaction region bump (IR bump) nonlinear correction method has been used for the sextupole and octupole field error on-line corrections in the Relativistic Heavy Ion Collider (RHIC). Some differences were found for the sextupole and octupole corrector strengths between the on-line IR bump correction and the predictions from the action-angle kick minimization. In this report we compare the corrector strengths from these two methods based on the RHIC Blue ring lattice with the IR nonlinear modeling. The comparison confirms the differences between resulting corrector strengths. And the reason for the differences is found and discussed. It is followed by a further discussion of the operational IR bump applications to the octupole, and skew sextupole and skew quadrupole field error corrections.

 
TPAP051 Principle of Global Decoupling with Coupling Angle Modulation 3132
 
  • Y. Luo, S. Peggs, F.C. Pilat, T. Roser, D. Trbojevic
    BNL, Upton, Long Island, New York
 
  Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886.

The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). A new scheme coupling phase modulation is found. It introduces a rotating extra coupling into the coupled machine to detect the residual coupling. The eigentune responses are measured with a high resolution phase lock loop (PLL) system. From the minimum and maximum tune splits, the correction strengths are given. The time period occupied by one coupling phase modulation is less than 10 seconds. So it is a very promising solution for the global decoupling on the ramp. In this article the principle of the coupling phase modulation is given. The simulation with the smooth accelerator model is also done. The practical issues concerning its applications are discussed.

 
TPAP052 Possible Phase Loop for the Global Decoupling 3182
 
  • Y. Luo, P. Cameron, A. Della Penna, A. Marusic, S. Peggs, T. Roser, D. Trbojevic
    BNL, Upton, Long Island, New York
  • O.R. Jones
    CERN, Geneva
 
  Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886.

Besides two eigentunes Q1 and Q2 , two amplitude ratios r1 and r2 and two phase differences ∆ φ1 and ∆ φ2 are introduced for the global coupling observation. Simulations are carried out to check their behaviors in the process of the skew quadrupole strength scans. Some attractive features of the phase differences ∆ φ1,2 have been found, which are possibly useful for the global decoupling phase loop, or future global decoupling feedback. Analytical descriptions to these 6 quantities are described in the Twiss parameters through the linear coupling's action-angle parameterization, or in coupling coefficient through the linear coupling's Hamiltonian perturbation theory. Dedicated beam experiments are carried out at the Relativistic Heavy Ion Collider (RHIC) to check the global coupling observables from the phase lock loop (PLL) system. The six observables are measured under PLL driving oscillations during the 1-D and 2-D skew quadrupole scans. The experimental results are reported and discussions are given.

 
TPAP053 IR Optics Measurement with Linear Coupling's Action-Angle Parameterization 3218
 
  • Y. Luo, M. Bai, F.C. Pilat, T. Satogata, D. Trbojevic
    BNL, Upton, Long Island, New York
 
  Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886.

The interaction region (IP) optics are measured with the two DX/BPMs close to the IPs at the Relativistic Heavy Ion Collider (RHIC). The beta functions at IP are measured with the two eigenmodes' phase advances between the two BPMs. And the beta waists are also determined through the beta functions at the two BPMs. The coupling parameters at the IPs are also given through the linear coupling's action-angle parameterization. All the experimental data are taken during the driving oscillations with the AC dipole. The methods to do these measurements are discussed. And the measurement results during the beta* squeezings are also presented.

 
TPPP019 Collective Effects in Lepton Ring of eRHIC 1628
 
  • D. Wang, M. Farkhondeh, C. Tschalaer, F. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • M. Blaskiewicz, Y. Luo, L. Wang
    BNL, Upton, Long Island, New York
 
  Funding: Department of Energy.

The eRHIC is a new generation lepton-hadron collider undergoing design studies by a collaboration of BNL, MIT, DESY and BINP. The collider complex will consist of a hadron machine that is mainly the existing RHIC with necessary upgrades, and a new lepton machine that can provide intense, highly polarized electron and positron beams at energy of 5-10 GeV. The ring-ring option of eRHIC is to build a 5-10 GeV electron ring with a injector chain. In this paper the beam lifetime of lepton beams is calculated.

 
WOAC007 Beam-Based Nonlinear Optics Corrections in Colliders 601
 
  • F.C. Pilat, Y. Luo, N. Malitsky, V. Ptitsyn
    BNL, Upton, Long Island, New York
 
  Funding: Work performed under the auspices of the US Department of Energy

A method has been developed to measure and correct operationally the non-linear effects of the final focusing magnets in colliders, which gives access to the effects of multi-pole errors by applying closed orbit bumps, and analyzing the resulting tune and orbit shifts. This technique has been tested and used during 3 years of RHIC (the Relativistic Heavy Ion Collider at BNL) operations. I will discuss here the theoretical basis of the method, the experimental set-up, the correction results, the present understanding of the machine model, the potential and limitations of the method itself as compared with other non linear correction techniques.

 
RPAP043 Beam-Based Alignment in the RHIC eCooling Solenoids 2771
 
  • P. Cameron, I. Ben-Zvi, W.C. Dawson, J. Kewisch, V. Litvinenko, Y. Luo, W.W. MacKay, C. Montag, J. Niedziela, V. Ptitsyn, T. Satogata, C. Schultheiss, V. Yakimenko
    BNL, Upton, Long Island, New York
 
  Funding: U.S. DOE.

Accurate alignment of the electron and ion beams in the RHIC electron cooling solenoids is crucial for well-optimized cooling. Because of the greatly differing rigidities of the electron and ion beams, to achieve the specified alignment accuracy it is required that transverse magnetic fields resulting from imperfections in solenoid fabrication be down by five orders of magnitude relative to the pure solenoid fields. Shimming the solenoid field to this accuracy might be accomplished by survey techniques prior to operation with beam, or by methods of beam-based alignment. We report on the details of a method of beam-based alignment, as well as the results of preliminary measurements with the ion beam at RHIC

 
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.

 
TPPE038 Thermal Hydraulic Design of PWT Accelerating Structures 2524
 
  • D. Yu, A. Baxter, P. Chen, M. Lundquist, Y. Luo
    DULY Research Inc., Rancho Palos Verdes, California
 
  Funding: Work supported by DOE SBIR Grant No. DE-FG02-03ER83846.

Microwave power losses on the surfaces of accelerating structures will transform to heat which will deform the structures if it is not removed in time. Thermal hydraulic design of the disk and cooling rods of a Plane Wave Transformer (PWT) structure is presented. Experiments to measure the hydraulic (pressure vs flow rate) and cooling (heat removed vs flow rate) properties of the PWT disk are performed, and results compared with simulations using Mathcad models and the COSMOSM code. Both experimental and simulation results showed that the heat deposited on the structure could be removed effectively using specially designed water-cooling circuits and the temperature of the structure could be controlled within the range required.

 
WPAT081 Ceramic Power Extractor Design at 15.6 GHz 4078
 
  • A. Smirnov, Y. Luo, R. Yi, D. Yu
    DULY Research Inc., Rancho Palos Verdes, California
 
  Funding: Work supported by DOE SBIR Grant No. DE-FG03-01ER83232.

Power extractor and coupler designs developed for an experiment planned at the 12th beam harmonic of the upgraded Advanced Wakefield Accelerator (AWA) facility is described. New features are an upstream HOM dielectric damper with additional tapering, and a single-port coupler considered in two variants. Performance analysis includes coupler geometric tolerances, overvoltage, dipole mode wake and BBU; and wakefield losses induced in the damper.

 
RPPP046 An L-Band Polarized Electron PWT Photoinjector for the International Linear Collider (ILC) 2902
 
  • D. Yu, A. Baxter, P. Chen, M. Lundquist, Y. Luo, A. S. Smirnov
    DULY Research Inc., Rancho Palos Verdes, California
 
  Funding: Work supported by DOE SBIR Grant No. DE-FG02-03ER83846.

A multi-cell, standing-wave, L-band, p-mode, plane-wave-transformer (PWT) photoinjector with an integrated photocathode in a novel linac structure is proposed by DULY Research Inc. as a polarized electron source. The PWT photoinjector is capable of operation in ultra high vacuum and moderate field gradient. Expected performance of an L-band polarized electron PWT injector operating under the parameters for the International Linear Collider is presented. The projected normalized transverse rms emittance is an order of magnitude lower than that produced with a polarized electron dc gun followed by subharmonic bunchers.