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A proton driver for the muon collider source with a tunable momentum compaction lattice

Description: The future Muon Collider will have a luminosity of the order of 10{sup 35} cm{sup {minus}2{minus}1} during 1,000 turns when the muons decay. This requires 10{sup 12} muons per bunch. The muon source is a 30 GeV proton driver with 2.5 10{sup 13} protons per pulse. The proton bunch length should be of the order of 1 ns. Short bunches could be created by a tunable momentum compaction lattice which would bring the momentum compaction to zero in a short time. This isochronous conduction would allow bunches to shear and become very short in time. The authors present a lattice where the momentum compaction is a tunable parameter at fixed horizontal and vertical betatron tunes. The values of the maxima of the dispersion function are kept small. They examine two kinds of lattices, with combined function as well as normal dipole and quadrupole magnets.
Date: July 1, 1997
Creator: Trbojevic, D.; Brennan, J.M.; Courant, E.D.; Roser, T.; Peggs, S.; Ng, K.Y. et al.
Partner: UNT Libraries Government Documents Department

A lattice for the muon collider demonstration ring in the RHIC tunnel

Description: The future {mu}{sup +}{mu}{sup {minus}} Muon Collider should have a luminosity of the order of 10{sup 35} cm{sup {minus}2} s{sup {minus}1}, and the energy of 2 x 2 TeV. The authors present here a demonstration machine at a lower energy to test the feasibility of all components involved, which could be placed inside the existing Relativistic Heavy Ion Collider (RHIC) tunnel. The maximum energy of the muons in the RHIC tunnel depends on the maximum attainable field in the dipoles. The maximum energy in the existing RHIC rings for protons is 250 GeV, where the strength of the magnetic field in the dipoles is 3.5 T. A design of the storage ring lattice for a 50 GeV muon demonstration machine is also presented.
Date: July 1, 1997
Creator: Trbojevic, D.; Palmer, R.B.; Courant, E.D.; Gallardo, J.; Peggs, S.; Tepikian, S. et al.
Partner: UNT Libraries Government Documents Department

Alignment of the high beta magnets in the RHIC interaction regions

Description: The betatron functions inside the triplet quadrupoles in the Relativistic Heavy Ion Collider-RHIC are of the order of 1,500 m, necessitating additional attention in the alignment procedure. On each side of the interaction regions eight cryogenic elements (six quadrupoles and two horizontal bending dipoles) are placed inside large cryostats. The quadrupole magnetic centers are obtained by antenna measurements with an accuracy of {+-} 60 {micro}m. The signals from the antenna were cross calibrated with the colloidal cell measurements of the same magnet. The positions of the fiducials are related to the magnet centers during the antenna measurements. Elements are positioned warm inside the cryostats, with offsets to account for shrinkage during the cool down. The supports at the middle of the two central quadrupoles are fixed, while every other element slides longitudinally inside the cryostat during cool down or warm up.
Date: July 1, 1997
Creator: Trbojevic, D.; Jain, A.; Tepikian, S.; Grandinetti, R.; Ganetis, G.; Wei, J. et al.
Partner: UNT Libraries Government Documents Department

Field quality evaluation of the superconducting magnets of the relativistic heavy ion collider

Description: In this paper, the authors first present the procedure established to evaluate the field quality, quench performance, and alignment of the superconducting magnets manufactured for the Relativistic Heavy Ion Collider (RHIC), and then discuss the strategies used to improve the field quality and to minimize undesirable effects by sorting the magnets. The field quality of the various RHIC magnets is briefly summarized.
Date: May 1, 1995
Creator: Wei, J.; Gupta, R.C.; Jain, A.; Peggs, S.G.; Trahern, C.G.; Trbojevic, D. et al.
Partner: UNT Libraries Government Documents Department

A study of RHIC crystal collimation

Description: The Relativistic Heavy Ion Collider (RHIC) will experience increasing longitudinal and transverse heavy ion emittances, mostly due to intra-beam scattering (IBS). The experiments in RHIC are expected to not only have reduced luminosities due to IBS but also background caused by beam halo. Primary betatron collimators will be used to remove the large amplitude particles. The efficiency of the primary collimator in RHIC strongly depends on the alignment of the jaws which needs to be within about ten micro-radians for the optimum conditions. As proposed by V. biryukov bent crystals could be used to improve the efficiency of an existing collimation system by installing them upstream of the collimator jaws. Bent crystals have been successfully used in SPS, Protvino and Fermilab for extraction of the beam particles channeled through them. This study examines possible improvements of the primary collimator system for heavy ions at RHIC by use of bent crystals. Bent crystals will reduce the collimator jaws alignment requirement and will increase collimator efficiency thereby reducing detector background.
Date: August 1, 1998
Creator: Trbojevic, D.; Harrison, M.; Parker, B.; Thompson, P.; Stevens, A.; Biryukov, V. et al.
Partner: UNT Libraries Government Documents Department

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