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Title |
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| MOPLT175 |
A Method to Measure the Focusing Properties (R_Matrix) of a Magnet
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935 |
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- N. Tsoupas, L. Ahrens, K.A. Brown, D. Gassner, J. Glenn, Y.Y. Lee, T. Roser, P. Thieberger, J. Wei
BNL, Upton, Long Island, New York
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We discuss a method that may be used to measure the focusing properties of a magnet. This method may prove valuable when applied to non-conventional magnets that deviate from the usual dipole magnets or other multipole magnets which are commonly used in a synchrotron. In this category of non-conventional magnets, fall special magnets, which come under the name Snakes. Such magnets are being used in synchrotron accelerators[*,**] to introduce artificial spin resonances to help overcome the intrinsic and/or imperfection spin resonances. This method of measuring the focusing properties of a magnet requires the use of low energy and high rigidity heavy-ions which may be obtained from the BNL Tandem accelerator.In brief the method consists on, injecting low emittance beamlets of lightly stripped heavy ions into a magnet and measuring the coordinates, of these narrowbeamlets, at the entrance and exit of the magnet.From the measurement of these coordinates of the narrowbeamlets we can deduce information on the R matrix and higher order matrix elements that define the focusing properties of the magnet.
* T. Roser, AIP Conf. Proc. 187 (1988) 1221** H.Huang, et. al. Phys. Rev. Lett. 73 (1994) 2982
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| MOPLT176 |
Mechanism of Electron Multipacting with a Long Bunch Proton Beam
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938 |
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- L. Wang, M. Blaskiewicz, J. Wei
BNL, Upton, Long Island, New York
- R.J. Macek
LANL/LANSCE, Los Alamos, New Mexico
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The mechanism of electron multipacting in long bunched proton machine has been quantitatively described by the electron energy gain and electron motion. Some important parameters related to electron multipacting are investigated in detail. It is proved that multipacting is sensitive to beam intensity, longitudinal beam profile shape and transverse beam size. Agreement is achieved among our analysis, simulation and experiment.
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| MOPLT177 |
Stochastic Cooling Power Requirements
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941 |
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- J. Wei, M. Blaskiewicz, J.M. Brennan
BNL, Upton, Long Island, New York
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A practical obstacle for stochastic cooling in high-energy colliders is the large amount of power needed for the cooling system. This paper discusses the cooling power needed for the longitudinal cooling process. Based on the coasting-beam Fokker-Planck equation, we analytically derived the optimum cooling rate and cooling power for a beam of uniform distribution and a cooling system of linear gain function. The results indicate that the usual back-of-envelope formula over-estimated the cooling power by a factor of the mixing factor $M$. On the other hand, the scaling laws derived from the coasting-beam Fokker-Planck approach agree with those derived from the bunched-beam Fokker-Planck approach if the peak beam intensity is used as the effective coasting-beam intensity. A longitudinal stochastic cooling system of 4 – 8 GHz bandwidth in RHIC can effectively counteract intrabeam scattering, preventing the beam from escaping the RF bucket becoming debunched around the ring.
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| TUPLT184 |
Operational Measurement of Coupling by Skew Quadrupole Modulation
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1559 |
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- Y. Luo, P. Cameron, R. Lee, A. Marusic, F.C. Pilat, T. Roser, D. Trbojevic, J. Wei
BNL, Upton, Long Island, New York
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The measurements of betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been recently developed and tested at RHIC. By modulating the current of different skew quadrupole families with different frequencies and measuring the resulting eigentunes response with a high resolution phase lock loop (PLL) system, it is possible to determine the projections of the residual coupling coefficients. We report the results of extensive beam studies carried on at RHIC injection, store energy and on the ramp. The capability of measuring coupling on the ramp opens the possibility of continuous coupling corrections during acceleration.
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| TUPLT185 |
Principle of Skew Quadrupole Modulation to Measure Betatron Coupling
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1562 |
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- Y. Luo, F.C. Pilat, T. Roser, D. Trbojevic, J. Wei
BNL, Upton, Long Island, New York
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The idea of modulating Skew Qudrupoles to measure the ring betatron coupling was put forth by T. Roser. In this paper, analytical solutions for this technique is given. Simulation are also carried out based on RHIC. And other relevent issues concerning this technique's application are also discussed. All of them show this idea of modulating skew qudrupoles to measure the betatron coupling are applicable.
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| TUPLT189 |
Dipole and Quaqdrupole Sorting for the SNS Ring
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1574 |
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- D. Raparia, A.V. Fedotov, Y.Y. Lee, J. Wei
BNL, Upton, Long Island, New York
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The Spallation Neutron Source (SNS) accumulator ring is a high intensity ring and must have low uncontrolled losses for hands on maintenance. To achieve these low losses one needs very tight tolerance. These tight tolerances have been achieved through shimming the magnets and sorting. Dipoles are solid core magnets and had very good field quality but magnet to magnet variation were sorted out according to ITF, since all the dipole are powered with one power supply. Typically, sorting is done to minimize linear effects in beam dynamics. Here, sorting of quadrupoles was done according to a scheme which allows to reduce unwanted strength of nonlinear resonances. As a result, the strength of sextupole resonances for our base line tune-box was strongly reduced which was confirmed by a subsequent beam dynamics simulation.
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| TUPLT192 |
Transition Crossing for the BNL Super Neutrino Beam
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1583 |
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- J. Wei, N. Tsoupas
BNL, Upton, Long Island, New York
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The super neutrino beam facility proposed at the Brookhaven National Laboratory requires proton beams to cross the transition energy in the AGS to reach 1 MW beam power at top energy. High intensity beams are accelerated at a fast repetition rate. Upon transition crossing, such high intensity bunches of large momentum spreads suffer from strong nonlinear chromatic effects and self-field effects. Using theoretical and experimental methods, we determine the impact of these effects and the effectiveness of transition-jump compensation schemes, and determine the optimum crossing scenario for the super neutrino beam facility.
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| WEOCCH02 |
Construction Status and Issues of the Spallation Neutron Source Ring
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156 |
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- J. Wei
BNL, Upton, Long Island, New York
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(For the Spallation Neutron Source collaboration) The Spallation Neutron Source (SNS) accelerator complex is now in its sixth year of a seven-year construction cycle. The design, fabrication, test, and assembly of the accumulator ring and its transport lines is approaching the final stage. In order to reach the design goal of this high-power ring to deliver 1.5 MW beam power (1.5$× 1014 protons of 1 GeV kinetic energy at a repetition rate of 60 Hz), stringent measures have been implemented to ensure the quality of the accelerator systems. This paper reviews the progress of the ring and transport systems with emphasis on the challenging technical issues and their solutions inccurred during the construction period.
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Video of talk
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Transparencies
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| WEPLT183 |
Clearing of Electron Cloud in SNS
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2245 |
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- L. Wang, Y.Y. Lee, D. Raparia, J. Wei, S.Y. Zhang
BNL, Upton, Long Island, New York
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In this paper we describe a mechanism using the clearing electrodes to remove the electron cloud in the Spallation Neutron Source (SNS) accumulator ring, where strong multipacting could happen at median clearing fields. A similar phenomenon was reported in an experimental study at Los Alamos laboratory's Proton Synchrotron Ring (PSR). We also investigated the effectiveness of the solenoid's clearing mechanism in the SNS, which differs from the short bunch case, such as in B-factories.
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| WEPLT184 |
Preliminary Estimation of the Electron Cloud in RHIC
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2248 |
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- L. Wang, P. He, J. Wei
BNL, Upton, Long Island, New York
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Electron cloud due to beam induce multipacting is suspected to be one of the source of pressure rises in RHIC. This paper estimates the possible electron cloud in RHIC. Various parameters related electron multipacting has been investigated.
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| THPLT171 |
Stochastic Cooling Studies in RHIC, II
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2858 |
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- M. Blaskiewicz, J.M. Brennan, J. Wei
BNL, Upton, Long Island, New York
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Intra-beam scattering is unavoidable for highly charged heavy ions and causes emittance growth during the store for collision physics. A longitudinal bunched beam stochastic cooling system will confine the bunch within the RF bucket increasing the useful luminosity. A single bunch, Palmer cooling system is under investigation. We present data and compare them with theory.
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| THPLT179 |
MADX-UAL Suite for Off-line Accelerator Design and Simulation
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2870 |
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- N. Malitsky, R.P. Fliller III, F.C. Pilat, V. Ptitsyn, S. Tepikian, J. Wei
BNL, Upton, Long Island, New York
- F. Schmidt
CERN, Geneva
- R.M. Talman
Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
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We present here an accelerator modeling suite that integrates the capability of MADX and UAL packages, based on the Standard eXchange Format (SXF) interface. The resulting environment introduces a one-stop collection of accelerator applications ranging from the lattice design to complex beam dynamics studies. The extended capabilities of the MADX-UAL integrated approach have been tested and effectively used in two accelerator projects: RHIC, where direct comparison of operational and simulated data is possible, and the SNS Accumulator Ring, still in its design phase.
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| MOPLT178 |
RHIC Pressure Rise
|
944 |
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- 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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| TUPLT186 |
Managing System Parameters for SNS Magnets and Power Supplies
|
1565 |
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- W.J. McGahern, S. Badea, F.M. Hemmer, H.-C. Hseuh, J.W. Jackson, A.K. Jain, F.X. Karl, R.F. Lambiase, Y.Y. Lee, C.J. Liaw, H. Ludewig, G.J. Mahler, W. Meng, C. Pai, C. Pearson, J. Rank, D. Raparia, J. Sandberg, S. Tepikian, N. Tsoupas, J. Tuozzolo, P. Wanderer, J. Wei, W.-T. Weng
BNL, Upton, Long Island, New York
- R. Cutler, J.J. Error, J. Galambos, M.P. Hechler, S. Henderson, P.S. Hokik, T. Hunter, G.R. Murdoch, K. Rust, J.P. Schubert
ORNL/SNS, Oak Ridge, Tennessee
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The Spallation Neutron Source (SNS), currently under construction at Oak Ridge, Tennessee, is a collaborative effort of six U.S. Department of Energy partner laboratories. With over 312 magnets and 251 power supplies that comprise the beam transport lines and the accumulator ring, it is a challenge to maintain a closed loop on the variable parameters that are integral to these two major systems. This paper addresses the input variables, responsibilities and design parameters used to define the SNS magnet and power supply systems.
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| WEPKF087 |
SNS Extraction Fast Kicker Pulsed Power System
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1810 |
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- W. Zhang, H. Hahn, J.-L. Mi, C. Pai, J. Sandberg, Y. Tan, N. Tsoupas, J. Tuozzolo, D.S. Warburton, J. Wei
BNL, Upton, Long Island, New York
- R. Cutler, K. Rust
ORNL/SNS, Oak Ridge, Tennessee
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The Spallation Neutron Source (SNS) is a next generation high intensity beam facility. Its Accumulator Ring Extraction Fast Kicker System is a very high peak power, high average power, high precision pulse-waveform, ultra-low beam impedance, and high repetition rated pulsed power system. It has been successfully design and developed at Brookhaven National Laboratory. This system will consist of fourteen identical high voltage modulators and fourteen extraction magnet sections located inside of the SNS accumulator ring. The overall system output will reach multiple GW peak power with 60 Pulse-per-second repetition rates. The techniques of reducing impedance, improving rise time, and minimizing ripples will be discussed. The lifetime considerations, issues of the system design, development and construction are presented in this paper.
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