| 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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| MOPLS021 |
Beam Pipe Desorption Rate in RHIC
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583 |
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- H. Huang, W. Fischer, P. He, H.-C. Hseuh, U. Iriso, V. Ptitsyn, D. Trbojevic, J. Wei, S.Y. Zhang
BNL, Upton, Long Island, New York
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Increase of beam intensity in RHIC has caused several decades of pressure rises in the warm sections during operation. This has been a major factor limiting the RHIC luminosity. About 250 meters of NEG coated beam pipes have been installed in many warm sections to ameliorate this problem. Beam ion induced desorption is one possible cause of pressure rises. A series beam studies in RHIC has been dedicated to estimate the desorption rate of various beam pipes (regular and NEG coated) at various warm sections. Correctors were used to generate local beam losses and consequently local pressure rises. The experiment results are presented and analyzed in this paper.
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| TUPLS025 |
Racetrack Non-scaling FFAG for Muon Acceleration
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1544 |
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- D. Trbojevic
BNL, Upton, Long Island, New York
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The non-scaling Fixed-Field Alternating Gradient (FFAG) machines have very strong focusing, large momentum acceptance, and small dispersion and betatron functions. This report is a study of using a compact non-scaling FFAG in combination with the superconducting linac to accelerate the muons. The drift space between two kinds of combined function magnets in the previous non-scaling FFAG is removed. The time of flight in the non-scaling FFAG has a parabolic dependence on momentum. The large energy acceptance of the machine requires matching between the linac and the non-scaling FFAG arcs for both the betatron and dispersion functions over the entire energy range.
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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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| TUPLS079 |
Hadron Cancer Therapy Complex Employing Non-scaling FFAG Accelerator and Fixed Field Gantry Design
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1681 |
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- E. Keil
CERN, Geneva
- A. Sessler
LBNL, Berkeley, California
- D. Trbojevic
BNL, Upton, Long Island, New York
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Non-scaling FFAG rings for cancer hadron therapy offer reduced physical aperture and large dynamic aperture as compared with scaling FFAGs. The variation of tune with energy implies the crossing of resonances during acceleration. Our design avoids intrinsic resonances, although imperfection resonances must still be crossed. We consider a system of three non-scaling FFAG rings for cancer therapy with 250 MeV protons and 400 MeV/u carbon ions. Hadrons are accelerated in a common RFQ and linear accelerator, and injected into the FFAG rings at v/c=0.1128. The H+/C6+ ions are accelerated in the two smaller/larger rings to 31 and 250 MeV/52.5 and 400 MeV/u kinetic energy, respectively. The lattices consist of symmetrical triplet cells with a straight section for RF cavities. The gantry with similar triplet cells accepts the whole required momentum range at fixed field. This unique design uses either High Temperature super-conductors or super-conducting magnets reducing gantry size and weight. Elements with a variable field at the beginning and at the end set the extracted beam at the correct position for the specific energy and adapt the beam to specific requirements during treatment.
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| WEPCH180 |
A Dramatically Reduced Size in the Gantry design for the Proton-Carbon Therapy
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2352 |
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- D. Trbojevic, R.C. Gupta, B. Parker
BNL, Upton, Long Island, New York
- E. Keil
CERN, Geneva
- A. Sessler
LBNL, Berkeley, California
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Gantries in the proton/carbon cancer therapy machines represent the major cost and are usually very large. This report explains a new way for the gantry design. The size and cost of the gantries are reduced, and their use is simplified by using the fixed magnetic field. The "new" gantry is made of a very large momentum acceptance non-scaling Fixed Field Alternating Gradient (FFAG) quarter and half arc beam lines. The gantry is made of combined function magnets with a very strong focusing and small dispersion function. Additional magnets with a fast response are required to allow adjustments of the beam position for different energies at the beginning of the gantry. The strong focusing magnets following the gantry have to be adjustable as well to provide the required spot size. The adjustable dipoles provide the radial scanning. The fixed field combined function magnets could be made of small permanent magnets for the proton machine, or of the high temperature superconductors or superconductors for the carbon machine, reducing dramatically the size.
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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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