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THE TWO STAGE CRYSTAL COLLIMATOR FOR RHIC.

Description: The use of a two stage crystal collimation system in the RHIC yellow ring is examined. The system includes a copper beam scraper and a bent silicon crystal. While scrapers were installed in both of the RHIC rings before the year 2000 run, the crystal is installed for the 2001 run in one ring only, forming a two stage collimation system there. We present simulations of the expected channeling through the bent silicon crystal for both protons and gold ions with various beam parameters. This gives a picture of the particle losses around the ring, and the expected channeling efficiency. These results are then used to optimize the beam parameters in the area of the crystal to obtain maximum channeling efficiency, minimize out-scattering in the secondary collimator, and reduce beam halo.
Date: June 18, 2001
Creator: FLILLER, R.P. III; DREES, A.; GASSNER, D.; HAMMONS, L.; MCINTYRE, G.; TRBOJEVIC, D. et al.
Partner: UNT Libraries Government Documents Department

UPGRADING RHIC FOR HIGHER LUMINOSITY.

Description: While RHIC has only just started running for its heavy ion physics program, in the first run last summer, we achieved 10% of the design luminosity. In this paper we discuss plans for increasing the luminosity by a factor of 35 beyond the nominal design. A factor of 4 should be straightforward by doubling the number of bunches per ring and squeezing the {beta}* from 2 to 1 m at selected interaction points. An additional factor of 8 to 10 could be possible by using electron cooling to counteract intrabeam scattering and reduce emittances of the beams.
Date: June 18, 2001
Creator: MACKAY,W.; BEN-ZVI,I.; BRENNAN,J.M.; HARRISON,M.; KEWISCH,J.; PEGGS,S. et al.
Partner: UNT Libraries Government Documents Department

RHIC AC DIPOLE DESIGN AND CONSTRUCTION.

Description: Two ac dipoles with vertical and horizontal magnetic field have been proposed at RHIC for applications in linear and non-linear beam dynamics and spin manipulations. A magnetic field amplitude of 380 Gm is required to produce a coherent oscillation of 5 times the rms beam size at the top energy. We take the ac dipole frequency to be 1.0% of the revolution frequency away from the betatron frequency. To achieve the strong magnetic field with minimum power loss, an air-core magnet with two seven turn winding of low loss Litz wire resonating at 64 kHz is designed. The system is also designed to allow one to connect the two magnet winding in series to resonate at 37 kHz for the spin manipulation. Measurements of a half length prototype magnet are also presented.
Date: June 18, 2001
Creator: BAI,M.; METH,M.; PAI,C.; PARKER,B.; PEGGS,S.; ROSER,T. et al.
Partner: UNT Libraries Government Documents Department

RHIC AC DIPOLE DESIGN AND CONSTRUCTION.

Description: Two ac dipoles with vertical and horizontal magnetic field have been proposed at RHIC for applications in linear and non-linear beam dynamics and spin manipulations. A magnetic field amplitude of 380 Gm is required to produce a coherent oscillation of 5 times the rms beam size at the top energy. We take the ac dipole frequency to be 1.0% of the revolution frequency away from the betatron frequency. To achieve the strong magnetic field with minimum power loss, an air-core magnet with two seven turn winding of low loss Litz wire resonating at 64 kHz is designed. The system is also designed to allow one to connect the two magnet winding in series to resonate at 37 kHz for the spin manipulation. Measurements of a half length prototype magnet are also presented.
Date: June 18, 2001
Creator: BAI,M.; METH,M.; PAI,C.; PARKER,B.; PEGGS,S.; ROSER,T. et al.
Partner: UNT Libraries Government Documents Department

UPGRADING THE AGS TO 1 MW PROTON BEAM POWER.

Description: The Brookhaven Alternating Gradient Synchrotron (AGS) is a strong focusing accelerator that is used to accelerate protons and various heavy ion species to an equivalent proton energy of 29 GeV. At this energy the maximum intensity achieved is around 7 x 10{sup 13} protons per pulse. This corresponds to an average beam power of about 0.2 MW. Future programs in high-energy physics, as for instance a neutrino factory with the AGS as the proton driver [l], may require an upgrade of the AGS to an average beam power of 1 MW, at the energy of 24 GeV. This can be achieved with an increase of the beam intensity to 1 x 1014 protons per pulse, a 1.2-GeV superconducting linac as a new injector, and by upgrading the power supply and rf systems to allow cycling at 2.5 beam pulses per second.
Date: June 18, 2001
Creator: BRENNAN,M.J.; MARNERIS,I.; ROSER,T.; RUGGIERO,A.G.; TRBOJEVIC,D. & ZHANG,S.Y.
Partner: UNT Libraries Government Documents Department

Design of the muon collider isochronous storage ring lattice

Description: The muon collider would ex-tend limitations of the e{sup +} e- colliders and provide new physics potentials with a possible discovery of the heavy Higgs bosons. At the maximum energy of 2 TeV the projected luminosity is of the order of 10{sup 35} cm{sup {minus}2}s{sup {minus}1}. The colliding {mu}{sup +} {mu}{sup {minus}} bunches have to be focused to a very small transverse size of few tenths of {mu}m which is accomplished by the betatron functions at the crossing point of {beta}* = 3mm. This requires the longitudinal space of the same length 3 mm. These very short bunches at 2 TeV could circulate only in a quasi-isochronous storage ring where the momentum compaction is very dose to zero. We report on a design of the muon collider isochronous lattice. The momentum compaction is brought to zero by having the average value of the dispersion function through dipoles equal to zero. This has been accomplished by a combination of the FODO cells together with a low beta insertion. The dispersion function oscillates between negative and positive values.
Date: December 1, 1995
Creator: Trbojevic, D.; Courant, E.D.; Lee, S.Y.; Gallardo, J.; Palmer, B.; Tepikian, S. et al.
Partner: UNT Libraries Government Documents Department

IMPROVEMENTS OF THE RHIC RAMP EFFICIENCY.

Description: The last nms in both gold-gold and polarized proton-proton required necessary corrections in the ramp as the intensities in the two rings were rising towards design values. Corrections were made with respect to the beam-beam effects, transverse and longitudinal instabilities, transition crossing (for the gold-gold ramps), transverse tune resonances, local and global coupliug problems, aperture restrictions, chromatic effects. Along the ramps we had to use the beam separation, ''Landau'' cavities, chromatic and tune control, orbit correction, special gamma-t quadrupole system for the transition crossing in the gold run, correction octupole circuits, beam position monitor system decoupling etc.
Date: June 2, 2002
Creator: TRBOJEVIC,D.; PTITSYN,V.; FISCHER,W.; AHRENS,L.; BLASKIEWICZ,M.; HAYES,T. et al.
Partner: UNT Libraries Government Documents Department

EXPERIMENTAL SET UP TO MEASURE COHERENT BREMSSTRAHLUNG AND BEAM PROFILES IN RHIC.

Description: A proposal for an experiment to detect and measure with an array infrared detector either the infrared radiation from the beam-beam coherent bremsstrahlung or from the synchrotron light from the edge effect of large DX RHIC magnet is described. Predictions for the 100 GeV/nucleon gold and 250 GeV proton signals from both bremsstrahlung and synchtrotron radiation magnet edge effect are shown.
Date: June 3, 2002
Creator: TRBOJEVIC,D.; GASNER,D.; MACKAY,W.; MCINTYRE,G.; PEGGS,S.; TEPIKIAN,S. et al.
Partner: UNT Libraries Government Documents Department

A transitionless lattice for the Fermilab Main Injector

Description: Medium energy (1 to 30 GeV) accelerators are often confronted with transition crossing during acceleration. A lattice without transition is presented, which is a design for the Fermilab Main Injector. The main properties of this lattice are that the {gamma}{sub t} is an imaginary number, the maxima of the dispersion function are small, and two long-straight section with zero dispersion. 7 refs., 5 figs.
Date: May 1, 1991
Creator: Ng, K.Y.; Trbojevic, D. (Fermi National Accelerator Lab., Batavia, IL (USA)) & Lee, S.Y. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Examination of the stability of the advanced imaginary. gamma. sub t lattice

Description: An advanced imaginary -{gamma}{sub t} lattice for the Fermilab Main Injector is examined for its response to quadrupole field errors, quadrupole misalignment errors, as well as its dynamical aperture. We find that the lattice is tunable except near an integer tune. The misalignment sensitivity factors are acceptable and can be lowered if the low-beta triplet quadrupoles are specially aligned. The dynamical aperture is very large provided that a family of harmonic sextupoles is installed. 6 refs., 4 figs.
Date: May 1, 1991
Creator: Ng, K.Y.; Trbojevic, D. (Fermi National Accelerator Lab., Batavia, IL (USA)) & Lee, S.Y. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

ELECTRON CLOUD OBSERVATIONS AND CURES IN RHIC.

Description: Since 2081 MIC has experienced electron cloud effects, which have limited the beam intensity. These include dynamic pressure rises - including pressure instabilities, tune shifts: electrons, a reduction of the stability threshold for bunches crossing the transition energy, and possibly slow emittance growth. We summarize the main observations in operation and dedicated experiments, as well as countermeasures including baking, NEG coated warm beam pipes, solenoids, bunch patterns, anti-grazing rings, pre-pumped cold beam pipes, and scrubbing.
Date: March 1, 2007
Creator: FISCHER,W.; BLASKIEWICZ, M.; HUAN, H.; HSEUH, H.C.; PTITSYN, V.; ROSER, T. et al.
Partner: UNT Libraries Government Documents Department

MeRHIC - staging approach to eRHIC

Description: Design of a medium energy electron-ion collider (MeRHIC) is under development at the Collider-Accelerator Department at BNL. The design envisions construction of a 4 GeV electron accelerator in a local area inside and near the RHIC tunnel. Electrons will be produced by a polarized electron source and accelerated in energy recovery linacs. Collisions of the electron beam with 100 GeV/u heavy ions or with 250 GeV polarized protons will be arranged in the existing IP2 interaction region of RHIC. The luminosity of electron-proton collisions at the 10{sup 32} cm{sup -2}s{sup -1} level will be achieved with 50 mA CW electron current and presently available proton beam parameters. Efficient proton beam cooling at collision energy may bring the luminosity to 10{sup 33} cm{sup -2}s{sup -1}. An important feature of MeRHIC is that it serves as a first stage of eRHIC, a future electron-ion collider at BNL with both higher luminosity and energy reach. The majority of MeRHIC accelerator components will be used in eRHIC.
Date: May 4, 2009
Creator: Ptitsyn,V.; Beebe-Wang, J.; Ben-Zvi, I.; Deshpande, A.; Fedotov, A.; Hao, Y. et al.
Partner: UNT Libraries Government Documents Department

Overview of magnetic nonlinear beam dynamics in the RHIC

Description: In this article we review our studies of nonlinear beam dynamics due to the nonlinear magnetic field errors in the Relativistic Heavy Ion Collider (RHIC). Nonlinear magnetic field errors, including magnetic field errors in interaction regions (IRs), chromatic sextupoles, and sextupole components from arc main dipoles are discussed. Their effects on beam dynamics and beam dynamic aperture are evaluated. The online methods to measure and correct the IR nonlinear field errors, second order chromaticities, and horizontal third order resonance are presented. The overall strategy for nonlinear corrections in RHIC is discussed.
Date: May 4, 2009
Creator: Luo,Y.; Bai, M.; Beebe-Wang, J.; Bengtsson, J.; Calaga, R.; Fischer, W. et al.
Partner: UNT Libraries Government Documents Department

ERHIC Conceptual Design

Description: The conceptual design of the high luminosity electron-ion collider, eRHIC, is presented. The goal of eRHIC is to provide collisions of electrons (and possibly positrons) with ions and protons at the center-of-mass energy range from 25 to 140 GeV, and with luminosities exceeding 10{sup 33} cm{sup -2} s{sup -1}. A considerable part of the physics program is based on polarized electrons, protons and He3 ions with high degree of polarization. In eRHIC electron beam will be accelerated in an energy recovery linac. Major R&D items for eRHIC include the development of a high intensity polarized electron source, studies of various aspects of energy recovery technology for high power beams and the development of compact magnets for recirculating passes. In eRHIC scheme the beam-beam interaction has several specific features, which have to be thoroughly studied. In order to maximize the collider luminosity, several upgrades of the existing RHIC accelerator are required. Those upgrades may include the increase of intensity as well as transverse and longitudinal cooling of ion and proton beams.
Date: August 25, 2008
Creator: Ptitsyn,V.; Beebe-Wang,J.; Ben-Zvi,I.; Fedotov, A.; Fischer, W.; Hao, Y. et al.
Partner: UNT Libraries Government Documents Department

Reduction of beta* and increase of luminosity at RHIC

Description: The reduction of {beta}* beyond the 1m design value at RHIC has been consistently achieved over the last 6 years of RHIC operations, resulting in an increase of luminosity for different running modes and species. During the recent 2007-08 deuteron-gold run the reduction to 0.70 from the design 1m achieved a 30% increase in delivered luminosity. The key ingredients allowing the reduction have been the capability of efficiently developing ramps with tune and coupling feedback, orbit corrections on the ramp, and collimation, to minimize beam losses in the final focus triplets, the main aperture limitations for the collision optics. We will describe the operational strategy used to reduce the {beta}*, at first squeezing the beam at store, to test feasibility, followed by the operationally preferred option of squeezing the beam during acceleration, and the resulting luminosity increase. We will conclude with future plans for the beta squeeze.
Date: May 4, 2009
Creator: Pilat,F.; Bai, M.; Bruno, D.; Cameron, P.; Della Penna, A.; Drees, A. et al.
Partner: UNT Libraries Government Documents Department

RHIC VERTICAL AC DIPOLE COMMISSIONING.

Description: The RHIC vertical ac dipole was installed in the summer of 2001. The magnet is located in the interaction region between sector 3 and sector 4 common to both beams. The resonant frequency of the ac dipole was first configured to be around half of the beam revolution frequency to act as a spin flipper. At the end of the RHIC 2002 run, the ac dipole frequency was reconfigured for linear optics studies. A 0.35 mm driven betatron oscillation was excited with the vertical ac dipole and the vertical betatron functions and phase advances at each beam position monitor (BPM) around the RHIC yellow ring were measured using the excited coherence. We also recorded horizontal turn-by-turn beam positions at each BPM location to investigate coupling effects. Analysis algorithms and measurement results are presented.
Date: June 2, 2002
Creator: BAI,M.; DELONG,J.; HOFF,L.; PAI,C.; PEGGS,S.; PIACENTINO,J. et al.
Partner: UNT Libraries Government Documents Department

COMMISSIONING OF THE RELATIVISTIC HEAVY ION COLLIDER.

Description: This report describes in detail steps performed in bringing the Relativistic Heavy Ion Collider (RHIC) from the commissioning into the operational stage when collisions between 60 bunches of fully striped gold ions, were routinely provided. Corrections of the few power supplies connections by the beam measurements are described. Beam lifetime improvements at injection, along the acceleration are shown. The beam diagnostic results; like Schottky detector, beam profile monitor, beam position monitors, tune meter and others, are shown [1].
Date: June 18, 2001
Creator: TRBOJEVIC,D.; AHRENS,L.; BLASKIEWICZ,M.; BRENNAN,M.; BAI,M.; CAMERON,P. et al.
Partner: UNT Libraries Government Documents Department

ELECTRON COOLING FOR RHIC.

Description: We introduce plans for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This project has a number of new features as electron coolers go: It will cool 100 GeV/nucleon ions with 50 MeV electrons; it will be the first attempt to cool a collider at storage-energy; and it will be the first cooler to use a bunched beam and a linear accelerator as the electron source. The linac will be superconducting with energy recovery. The electron source will be based on a photocathode gun. The project is carried out by the Collider-Accelerator Department at BNL in collaboration with the Budker Institute of Nuclear Physics.
Date: June 18, 2001
Creator: BEN-ZVI,I.; AHRENS,L.; BRENNAN,M.; HARRISON,M.; KEWISCH,J.; MACKAY,W. et al.
Partner: UNT Libraries Government Documents Department

Design of a non-scaling FFAG accelerator for proton therapy

Description: In recent years there has been a revival of interest in Fixed Field Alternating Gradient (FFAG) accelerators. In Japan a number have been built, or are under construction. A new non-scaling approach to the FFAG reduces the required orbit offsets during acceleration and the size of the required aperture, while maintaining the advantage of the low cost magnets associated with fixed fields. An advantage of the non-scaling FFAG accelerator, with respect to synchrotrons, is the fixed field and hence the possibility of high current and high repetition rate for spot scanning. There are possible advantages of the nonscaling design with respect to fixed-field cyclotrons. The non-scaling FFAG allows strong focusing and hence smaller aperture requirements compared to scaling designs, thus leading to very low losses and better control over the beam. We present, here, a non-scaling FFAG designed to be used for proton therapy.
Date: April 1, 2005
Creator: Trbojevic, D.; Ruggiero, A.G.; Keil, E.; Neskovic, N.; Belgrade, Vinca & Sessler, A.
Partner: UNT Libraries Government Documents Department

CRYSTAL COLLIMATION AT RHIC.

Description: For the year 2001 run, a bent crystal was installed in the yellow ring of the Relativistic Heavy Ion Collider (RHIC). The crystal forms the first stage of a two stage collimation system. By aligning the crystal to the beam, halo particles are channeled through the crystal and deflected into a copper scraper. The purpose is to reduce beam halo with greater efficiency than with a scraper alone. In this paper we present the first results from the use of the crystal collimator. We compare the crystal performance under various conditions, such as different particle species, and beta functions.
Date: June 2, 2002
Creator: FLILLER,III, R.P.; DREES,A.; GASSNER,D.; HAMMONS,L.; MCINTYRE,G.; PEGGS,S. et al.
Partner: UNT Libraries Government Documents Department