| Paper |
Title |
Page |
| MOPLT164 |
Bunch Patterns and Pressure Rise in RHIC
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914 |
| |
- W. Fischer, U. Iriso
BNL, Upton, Long Island, New York
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The RHIC luminosity is limited by pressure rises with high intensity beams. At injection, the dominating cause for the pressure rise was shown to be electron clouds. We discuss the distributions of bunches along the circumference that minimize the electron cloud effect in RHIC. Experimental data are compared with simulation results, and experiences at the B-factories.
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| WEPLT177 |
Analysis of Electron Cloud at RHIC
|
2236 |
| |
- U. Iriso, M. Blaskiewicz, P. Cameron, K.A. Drees, W. Fischer, H.-C. Hseuh, R. Lee, S. Peggs, L. Smart, D. Trbojevic, S.Y. Zhang
BNL, Upton, Long Island, New York
- G. Rumolo
GSI, Darmstadt
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Pressure rises with high intense beams are becoming the main luminosity limitation at RHIC. Observations during the latest runs show beam induced electron multipacting as one of the causes for these pressure rises. Experimental studies are carried out at RHIC using devoted instrumentation to understand the mechanism leading to electron clouds. Possible cures using NEG coated beam pipes and solenoids are experimentally tested. In the following, we report the experimental electron cloud data and analyzed the results using computer simulation codes.
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| THPLT177 |
Maps for Fast Electron Cloud Simulations at RHIC
|
2867 |
| |
- U. Iriso, S. Peggs
BNL, Upton, Long Island, New York
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Luminosity in several colliders, including RHIC, is limited by the electron cloud effect. A careful re-distribution of the bunch pattern around the azimuth of a ring can decrease the average electron density for a fixed total bunch current, allowing the luminosity to be increased. In the search for a bunch pattern that maximizes the luminosity, a fast computer simulation is a key requirement. We discuss the use of fast polynomial maps to simulate the bunch to bunch evolution of the electron density at RHIC. Such maps are empirically derived from existing conventional slow simulation codes.
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| MOPLT165 |
Luminosity Increases in Gold-gold Operation in RHIC
|
917 |
| |
- W. Fischer, L. Ahrens, J. Alessi, M. Bai, D. Barton, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, D. Bruno, J. Butler, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, W. Fu, G. Ganetis, J. Glenn, T. Hayes, P. He, H.-C. Hseuh, H. Huang, P. Ingrassia, U. Iriso, R. Lee, Y. Luo, W.W. MacKay, G. Marr, A. Marusic, R. Michnoff, C. Montag, J. Morris, T. Nicoletti, B. Oerter, C. Pearson, S. Peggs, A. Pendzick, F.C. Pilat, V. Ptitsyn, T. Roser, J. Sandberg, T. Satogata, C. Schultheiss, A. Sidi-Yekhlef, L. Smart, S. Tepikian, R. Tomas, D. Trbojevic, N. Tsoupas, J. Tuozzolo, J. Van Zeijts, K. Vetter, K. Yip, A. Zaltsman, S.Y. Zhang, W. Zhang
BNL, Upton, Long Island, New York
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After an exploratory phase, during which a number of beam parameters were varied, the RHIC experiments now demand high luminosity to study heavy ion collisions in detail. Presently RHIC operates routinely above its design luminosity. In the first 4 weeks of its current operating period (Run-4) the machine has delivered more integrated luminosity that during the 14 weeks of the last gold-gold operating period (Run-2). We give an overview of the changes that increased the instantaneous luminosity and luminosity lifetime, raised the reliability, and improved the operational efficiency.
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| MOPLT178 |
RHIC Pressure Rise
|
944 |
| |
- S.Y. Zhang, J. Alessi, M. Bai, M. Blaskiewicz, P. Cameron, K.A. Drees, W. Fischer, R.P. Fliller III, D. Gassner, J. Gullotta, P. He, H.-C. Hseuh, H. Huang, U. Iriso, R. Lee, Y. Luo, W.W. MacKay, C. Montag, B. Oerter, S. Peggs, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, L. Smart, P. Thieberger, D. Trbojevic, J. Van Zeijts, L. Wang, J. Wei, K. Zeno
BNL, Upton, Long Island, New York
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Beam induced pressure rise remains an intensity limit at the RHIC for both heavy ion and polarized proton operations. The beam injection pressure rise at warm sections has been diagnosed due to electron cloud effect. In addition, pressure rise of heavy ion operation at the beam transition has caused experiment background problem in deuteron-gold run, and it is expected to take place in gold-gold run at high intensities. This type of pressure rise is related to beam momentum spread, and the electron cloud seems not dominant. Extensive approaches for both diagnosis and looking-for-remedies are undergoing in the current gold operation, RUN 4. Results of beam scrubbing, NEG pipe in RHIC ring, beam scraping test of ion desorption, beam momentum effect at the transition, beam gap effect, solenoid effect, and NEG pipe ion desorption test stand will be presented.
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