| Paper |
Title |
Page |
| MOPCH102 |
A Straight Section Design in RHIC to Allow Heavy Ion Electron Cooling
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279 |
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- D. Trbojevic, J. Kewisch, W.W. MacKay, T. Roser, S. Tepikian
BNL, Upton, Long Island, New York
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The Relativistic Heavy Ion Collider (RHIC) has been continuously producing exciting results. One of the major luminosity limitations of the present collider is the intra beam scattering. A path towards the higher luminosities requires cooling of the heavy ion beams. Two projects in parallel electron and stochastic cooling are progressing very well. To allow interaction between electrons and the RHIC beams it is necessary to redesign one of the existing interaction regions in RHIC to allow for the longer straight section with fixed and large values of the betatron functions. We present a new design of the interaction region for the electron cooling in RHIC.
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| MOPCH100 |
Polarized Proton Acceleration in the AGS with Two Helical Partial Snakes
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273 |
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- H. Huang, L. Ahrens, M. Bai, A. Bravar, K.A. Brown, E.D. Courant, C.J. Gardner, J. Glenn, A.U. Luccio, W.W. MacKay, V. Ptitsyn, T. Roser, S. Tepikian, N. Tsoupas, J. Wood, K. Yip, A. Zelenski, K. Zeno
BNL, Upton, Long Island, New York
- F. Lin
IUCF, Bloomington, Indiana
- M. Okamura, J. Takano
RIKEN, Saitama
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Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and it is not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results. The effect of horizontal intrinsic resonances in the presence of two partial snakes are also discussed.
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| MOPLS023 |
Status of Fast IR Orbit Feedback at RHIC
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589 |
| |
- C. Montag, J. Cupolo, J. Glenn, V. Litvinenko, A. Marusic, W. Meng, R.J. Michnoff, T. Roser, C. Schultheiss, J.E. Tuozzolo
BNL, Upton, Long Island, New York
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To compensate modulated beam-beam offsets caused by mechanical vibrations of IR triplet quadrupoles at frequencies around 10 Hz, a fast IR orbit feedback system has been developed. We report design considerations and recent status of the system.
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| TUPLS027 |
A Non-scaling FFAG for Radioactive Beams Acceleration (RIA)
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1547 |
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- D. Trbojevic, T. Roser, A.G. Ruggiero
BNL, Upton, Long Island, New York
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One of the most expensive components of proposals to accelerate heavy radioactive beams is the superconducting linac. This is an attempt to design a non-scaling Fixed-Field Alternating-Gradient (FFAG) lattice to allow acceleration of heavy radioactive beams in a short time period with an acceptance in momentum of ±50%. As it had been previously reported the non-scaling FFAG has very small orbit offsets, very strong focusing, and large momentum acceptance. The lattice with small combined function magnets would provide substantial savings in the cost of the RF.
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| THPCH027 |
An Experimental Proposal to Study Heavy-ion Cooling in the AGS due to Beam Gas or the Intrabeam Scattering
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2838 |
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- D. Trbojevic, L. Ahrens, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, W.W. MacKay, G. Parzen, T. Roser
BNL, Upton, Long Island, New York
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Low emittance of not-fully-stripped gold(Z=79) Au+77 Helium-like ion beams from the AGS (Alternating Gradient Synchrotron) could be attributed to the cooling phenomenon due to inelastic intrabeam scattering [1]. The low emittance gold beams have always been observed at injection in the Relativistic Heavy Ion Collider (RHIC). There have been previous attempts to attribute the low emittance to a cooling due to the exchange of energy between ions during the inelastic intrabeam scattering. The Fano-Lichten theory[2] of electron promotion might be applied during inelastic collisions between helium like gold ions in the AGS. During collisions if the ion energy is large enough, a quasi-molecule could be formed, and electron excitation could occur. During de-excitation of electrons, photons are emitted and a loss of total bunch energy could occur. This would lead to smaller beam size. We propose to inject gold ions with two missing electrons into RHIC at injection energy and study the beam behavior with bunched and de-bunched beam, varying the RF voltage and the beam intensity. If the "cooling" is observed additional.
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| MOPLS024 |
RHIC Performance as Polarized Proton Collider in Run-6
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592 |
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- V. Ptitsyn, L. Ahrens, M. Bai, D.S. Barton, J. Beebe-Wang, M. Blaskiewicz, A. Bravar, J.M. Brennan, K.A. Brown, D. Bruno, G. Bunce, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, A.V. Fedotov, W. Fischer, G. Ganetis, H. Hahn, T. Hayes, H.-C. Hseuh, H. Huang, P. Ingrassia, D. Kayran, J. Kewisch, R.C. Lee, V. Litvinenko, A.U. Luccio, Y. Luo, W.W. MacKay, Y. Makdisi, N. Malitsky, G.J. Marr, A. Marusic, R.J. Michnoff, C. Montag, J. Morris, T. Nicoletti, B. Oerter, F.C. Pilat, P.H. Pile, T. Roser, T. Russo, J. Sandberg, T. Satogata, C. Schultheiss, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
BNL, Upton, Long Island, New York
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The Relativistic Heavy Ion Collider in Run-6 was operating in polarized proton mode. With two Siberian Snakes per ring, the polarized protons were brought into collisions at 100 Gev and 31.2 Gev energies. The control of polarization orientation at STAR and PHENIX experiments was done using helical spin rotators. Physics studies were conducted with longitudinal, vertical and radial beam polarization at collision points. This paper presents the performance of RHIC as a polarized proton collider in the Run-6 with emphasis on beam polarization and luminosity issues.
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| MOPLS025 |
Experience in Reducing Electron Cloud and Dynamic Pressure Rise in Warm and Cold Regions in RHIC
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595 |
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- S.Y. Zhang, L. Ahrens, J.G. Alessi, M. Bai, M. Blaskiewicz, P. Cameron, R. Connolly, K.A. Drees, W. Fischer, J. Gullotta, P. He, H.-C. Hseuh, H. Huang, R.C. Lee, V. Litvinenko, W.W. MacKay, C. Montag, T. Nicoletti, B. Oerter, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, L. Smart, L. Snydstrup, S. Tepikian, P. Thieberger, D. Trbojevic, J. Wei, K. Zeno
BNL, Upton, Long Island, New York
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Significant improvement has been achieved for reducing electron cloud and dynamic pressure rise at RHIC over several years; however, there remain to be factors limiting luminosity. The large scale application of non-evaporable getter (NEG) coating in RHIC has been proven effective in reducing electron multipacting and dynamic pressure rise. This will be reported together with the study of the saturated NEG coatings. Since beams with increased intensity and shorter bunch spacing became possible in operation, the electron cloud effects on beam, such as the emittance growth,are an increasing concern. Observations and studies are reported. We also report the study results relevant to the RHIC electron cloud and pressure rise improvement, such as the effect of anti-grazing ridges on electron cloud in warm sections, and the effect of pre-pumping in cryogenic regions.
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| MOPLS058 |
eRHIC - Future Machine for Experiments on Electron-ion Collisions
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676 |
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- V. Ptitsyn, J. Beebe-Wang, I. Ben-Zvi, A.V. Fedotov, W. Fischer, W. Graves, V. Litvinenko, W.W. MacKay, C. Montag, S. Ozaki, T. Roser, S. Tepikian, D. Trbojevic
BNL, Upton, Long Island, New York
- D.P. Barber
DESY, Hamburg
- W.A. Franklin, R. Milner, B. Surrow, C. Tschalaer, E. Tsentalovich, D. Wang, F. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
MIT, Middleton, Massachusetts
- A.V. Otboev, Y.M. Shatunov
BINP SB RAS, Novosibirsk
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The paper presents recent developments for the design of the high luminosity electron-ion collider, eRHIC, proposed on the basis of the existing RHIC machine. The goal of eRHIC is to provide collisions of electrons and positrons on ions and protons in the center-of-mass energy range from 30 to 100 GeV. Lepton beams as well as the beam of protons (and, possibly, light ions) should be polarized. Two independent designs are under development, the so-called 'ring-ring' and 'linac-ring' options. The 'ring-ring' option is based on a 10 GeV electron storage ring. The design issues for the 'ring-ring' option are similar to those at existing B-factories. In the 'linac-ring' option, the electron beam is accelerated in a 10 GeV recirculating energy recovery linac. This option may provide higher luminosities (> 1·1033 cm-2s-1 for e-p collisions), but requires considerable R&D studies for a high current electron polarized source. In order to maximize the collider luminosity, ion ring upgrades, such as electron cooling and ion beam intensity increase, are considered.
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