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Antiproton stacking in the Recycler

Description: Possibilities to accumulate antiprotons in the Recycler are considered for three different cases: with current stochastic cooling, with upgraded stochastic cooling and with electron cooling. With stochastic cooling only, even upgraded, Recycler looks hardly useful. However, with electron cooling at its goal parameters and reasonably good vacuum in the Recycler, this machine would be efficient.
Date: June 23, 2003
Creator: Burov, Alexey
Partner: UNT Libraries Government Documents Department

Particle diffusion in overlapping resonances

Description: Longitudinal bunch dilution was studied in the IUCF Cooler Ring with phase modulation of a higher-order harmonic rf. Diffusion in the presence of overlapping parametric resonances has been identified as the dilution mechanism. We found that fast growth is associated with the rapid particle motion along separatrices of dominant parametric resonances, slow growth is related to particle diffusion in the chaotic sea, and saturation occurs when particles are bounded by an invariant torus.
Date: January 1, 1998
Creator: Ng, K.Y.
Partner: UNT Libraries Government Documents Department


Description: In this paper, we discuss various electron cooling dynamics studies for RHIC. We also present simulations [1] of various possibilities of using electron cooling at RHIC, which includes cooling at the top energy, pre-cooling at low energy, aspects of transverse and longitudinal cooling and their impact on the luminosity. Electron cooling at various collision energies both for heavy ions and protons is also discussed.
Date: May 16, 2005
Partner: UNT Libraries Government Documents Department

Status of Proof-of-principle Experiment for Coherent Electron Cooling

Description: Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o'clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.
Date: July 1, 2012
Creator: Pinayev, I.; Ben-Zvi, I.; Bengtsson, J.; Elizarov, A.; Fedotov, A. V.; Gassner, D. M. et al.
Partner: UNT Libraries Government Documents Department


Description: A comprehensive examination of theoretical models for the friction force, in use by the electron cooling community, was performed. Here, they present their insights about the models gained as a result of comparison between the friction force formulas and direct numerical simulations, as well as studies of the cooling process as a whole.
Date: May 29, 2006
Partner: UNT Libraries Government Documents Department


Description: The second part of the sixth RHIC Spin Collaboration (RSC) meeting was held on November 15, 2001 at Brookhaven National Laboratory. Previous meetings have elaborated on the new generation of proton spin-structure studies (e.g. gluon polarization and flavor separation of q and {bar q} polarizations via real W{sup {+-}} production) enabled by studying polarized proton collisions at energies and momentum transfers where perturbative QCD models are expected to be applicable. The focus of this meeting was on many of the experimental issues that must be resolved to achieve these physics goals. This summary is written with the benefit of hindsight following the completion of the first-ever run of a polarized proton collider. This first run can be considered as a successfully completed milestone of the RHIC Spin Collaboration. Other milestones remain important. Long term machine items were identified in Waldo Mackay's talk, the most important being the completion of the spin rotator magnets that will be installed in 2002 to allow the flexible orientation of the proton beam polarization at the PHENM and STAR experiments. At the meeting Waldo discussed a stronger partial snake magnet for the AGS as a means of producing highly polarized proton beams to inject into RHIC. Developments subsequent to this meeting suggest that a superconducting helical dipole magnet may be feasible for the AGS, and is likely to be needed to achieve the 70% beam polarization in RHIC. Longer term items were also presented, including potential increases in luminosity by the addition of electron cooling to RHIC and the possibility of increasing the collision energy by {approx}20% by replacement of the DX magnets. These items could be considered for a second generation of RHIC spin experiments. The other topics covered at the meeting were related to polarimetry and to the absolute calibration of the proton ...
Date: November 15, 2001
Creator: Bland, L. & Saito, N.
Partner: UNT Libraries Government Documents Department

Prospectus for an electron cooling system for the recycler

Description: The Recycler ring was added to the Main Injector (MI) project in 1997 as means to recover the antiprotons remaining at the end of Tevatron stores and to serve as a second stage accumulator to raise the maximum stack current. This report describes an electron cooling system with substan-tially higher stack capacity than the Recycler stochastic cooling system which could be brought into operation toward the end of Run II. It is the major component of a program to double the de-sign Run II luminosity and should have a positive effect on integrated luminosity soon after turn-on. The upgrade potential is intended to meet the longer term needs of the Laboratory�s luminosity upgrade program. The current experience with electron cooling is discussed to provide the ratio-nale for the choice of design parameters and to make clear the needs for additional development work. Both analytical and numerical development of the theory has been pursued to confirm that the limits in principle are well beyond foreseen need. The specific hardware described is not the only realization that has been considered, but it is in some ways the most conservative. The gen-eral scheme of using an electrostatic accelerator with high efficiency charge recovery was actively discussed in the 1980�s. Recent developments have served to build confidence in this approach, but, by whatever means realized, a Recycler electron cooling system will require significant extension of current practice. The Prospectus incorporates the ideas and understanding current 15 September 1998. Rapid progress toward a comprehensive development plan at this time means that its details will already differ from ideas now current.
Date: November 1, 1998
Creator: J.A. MacLachlan, Editor
Partner: UNT Libraries Government Documents Department

Fermilab R{ampersand}D program in medium energyelectron cooling

Description: Fermilab began an R & D program in medium energy electron cooling in April 1995 with the object of cooling 8 GeV antiprotons in a new 3.3 km permanent magnet storage ring (Recycler) to be built in the same tunnel as the Main Injector (MI). The MI is to be completed in 1998, and it is planned to install the Recycler by the end of 1997 to reduce interference during the final rush of MI installation. Although the Recycler will employ stochastic cooling initially, its potential for contributing an order of magnitude to Tevatron collider luminosity is tied to electron cooling. The short time scale and Fermilab`s limited familiarity with low energy electron beams has given rise to a two-phase development plan. The first phase is to build a cooling system based on an electron beam of {ge} 200 mA before year 2000. The second phase of about 3 years is planned to reach electron current of 2 A or more. This report describes the general scheme for high luminosity collider operation as well as the R & D plan and progress to date. 17 refs., 5 figs., 1 tab.
Date: July 1, 1996
Creator: MacLachlan, J.A.
Partner: UNT Libraries Government Documents Department

Contributions to the second workshop on medium energy electron cooling - MEEC96

Description: MEEC96 was a workshop devoted primarily to discussion within four working groups, not a mini-conference of prepared reports. Therefore, although there are contributions bearing the name of a single author, much of what was learned came in extemporaneous discussion of the issues posed to the participants. The original plan to produce formal proceedings has been dropped because of the limited number of participants willing to write up their own contributions and because of the difficulty of converting free-wheeling discussion to the written word. The premsise for the 1996 gathering was to set a critique of Fermilab`s R&D effort at cooling a ring of 8 GeV {bar p}`s. Separate abstracts have been submitted to the energy database for contributions to this workshop.
Date: September 1, 1997
Creator: MacLachlan, J.
Partner: UNT Libraries Government Documents Department

High current magnetized plasma discharges and electron beams for capture and cooling of charged leptons and hadrons

Description: Nowadays most magnetic lenses used to capture and to focus pions and muons utilize azimuthal magnetic fields generated by large axial currents, like horns or lithium rods (or even a Z-pinch at GSI). Capture and focusing angle is proportional to the product of the current and length of the lens. State-of-the-art for these lenses is no more than 750 kA and 70 cm. A meter long, multi-MA, magnetized axial discharges were generated by the early days of fusion. Lenses based of such devices can increase the capture angle of pions, e.g., by more than a factor of 2. Electron beam cooling is presently achieved in storage rings by having charged particles interact with a co-moving electron beam. In these devices, typical parameters are electron beam currents of about 1 A, an interaction length of about 1 meter, and interaction time of about 30 msec. Multi-MA electron beams can be used for single-pass final stage cooling in a number of machines. Calculations for some applications, as well as other advantages indicate that these schemes deserve further more serious consideration.
Date: July 1, 1997
Creator: Hershcovitch, A.
Partner: UNT Libraries Government Documents Department

Gun and optics calculations for the Fermilab recirculation experiment

Description: Fermilab is investigating electron cooling to recycle 8 Gev antiprotons recovered from the Tevatron. To do so, it is developing an experiment to recirculate 2 Mev electrons generated by a Pelletron at National Electrostatics Corporation. This paper reports on the optics calculations done in support of that work. We have used the computer codes EGN2 and MacTrace to represent the gun area and acceleration columns respectively. In addition to the results of our simulations, we discuss some of the problems encountered in interfacing the two codes.
Date: October 1, 1997
Creator: Kroc, T.
Partner: UNT Libraries Government Documents Department

Electron cooling for RHIC

Description: Electron cooling of completely stripped gold ions {sup 197}Au{sup 79+} in RHIC is considered for the store energy, {gamma} = 108. The optimal parameters of the required electron storage ring are discussed and proposed. The cooling time is calculated as 15 minutes, which would allow not only to avoid the beam loss due to the intra-beam scattering, but also reduce the transverse emittance and increase the luminosity several times.
Date: September 25, 1998
Creator: Burov, A., FNAL,
Partner: UNT Libraries Government Documents Department


Description: The Accelerator Collider Department (CAD) at Brookhaven National Laboratory is operating the Relativistic Heavy Ion Collider (RHIC), which includes the dual-ring, 3.834 km circumference superconducting collider and the venerable AGS as the last part of the RHIC injection chain. CAD is planning on a luminosity upgrade of the machine under the designation RHIC II. One important component of the RHIC II upgrade is electron cooling of RHIC gold ion beams. For this purpose, BNL and the Budker Institute of Nuclear Physics in Novosibirsk entered into a collaboration aimed initially at the development of the electron cooling conceptual design, resolution of technical issues, and finally extend the collaboration towards the construction and commissioning of the cooler. Many of the results presented in this paper are derived from the Electron Cooling for RHIC Design Report [1], produced by the, BINP team within the framework of this collaboration. BNL is also collaborating with Fermi National Laboratory, Thomas Jefferson National Accelerator Facility and the University of Indiana on various aspects of electron cooling.
Date: May 13, 2001
Creator: BEN-ZVI,I.
Partner: UNT Libraries Government Documents Department

One-dimensional ordering of ultra-low density ion beams in a storage ring

Description: The two-particle model, first introduced by Hasse, is employed to predict the beam temperature at which a one-dimensional ordered state of ions will be established in a cooler storage ring. The proposed state does not have the ions (in the beam frame) at rest, but simply has them not passing each other; i.e., remaining in the same (ordered) sequence. The model is applicable to an ultra-low density beam where collective Coulomb interactions are negligible. It is pointed out that the nature of the anomalous beam behavior observed in electron-cooling experiments at GSI (Darmstadt) and MSL (Stockholm) is approximately free from such parameters as the lattice design, ion species, beam density and energy. On the basis of the model, which is put in Hamiltonian form, scaled, and numerically studied, a universal criterion of one-dimensional beam ordering at low line density is derived. Analytic work is employed to explain the numerical results and derives an approximate criterion.
Date: February 27, 2004
Creator: Okamoto, H.; Okabe, K.; Yuri, Y.; Mohl, D. & Sessler, A.M.
Partner: UNT Libraries Government Documents Department

Toward a cold electron beam in the Fermilab's Electron Cooler

Description: Fermilab is developing a high-energy electron cooling system to cool 8.9-GeV/c antiprotons in the Recycler ring [1]. Cooling of antiprotons requires a round electron beam with a small angular spread propagating through 20-m long cooling section with a kinetic energy of 4.3 MeV. To confine the electron beam tightly and to keep its transverse angles below 0.1 mrad, the cooling section will be immersed into a solenoidal field of 50-150G. This paper describes the technique of measuring and adjusting the magnetic field quality in the cooling section and presents preliminary results of beam quality measurements in the cooler prototype.
Date: May 12, 2004
Creator: al., Vitali S. Tupikov et
Partner: UNT Libraries Government Documents Department

Status of the Fermilab Recycler

Description: The author presents the current operational status of the Fermilab Recycler Ring. Using a mix of stochastic and electron cooling, we prepare antiproton beams for the Fermilab Tevatron Collider program. Included are discussion of stashing and cooling performance, operational scenarios, and collider performance.
Date: September 1, 2007
Creator: Derwent, P.F.
Partner: UNT Libraries Government Documents Department

Transverse digital damper system for the Fermilab anti-proton recycler

Description: A transverse damping system is used in the Recycler at Fermilab to damp beam instabilities which arise from large beam intensities with electron cooling. Initial tests of electron cooling demonstrated beam loss due to transverse beam motion when the beam was cooled past the beam density threshold. The transverse damper system consists of two horizontal and two vertical pickups whose signals are amplified and passed into an analog hybrid to generate a difference signal from each pickup. The difference signals are input to a custom digital damper board which digitizes the analog signals at 212mhz, performs digital processing of the signals inside a large Altera Stratix II FPGA, then provides analog output at 212mhz via digital to analog converters. The digital damper output is sent to amplifiers which drive one horizontal and one vertical kicker. An initial prototype digital damper board has been successfully used in the Recycler for over six months. Currently, work is underway to replace the prototype board with an upgraded VME version.
Date: May 1, 2006
Creator: Eddy, N. & Crisp, J.
Partner: UNT Libraries Government Documents Department

Results of head-on beam-beam compensation studies at the Tevatron

Description: At the Tevatron collider, we studied the feasibility of suppressing the antiproton head-on beam-beamtune spread using a magnetically confined 5-keV electron beam with Gaussian transverse profile overlapping with the circulating beam. When electron cooling of antiprotons is applied in regular Tevatron operations, the head-on beam-beam effect on antiprotons is small. Therefore, we first focused on the operational aspects, such as beam alignment and stability, and on fundamental observations of tune shifts, tune spreads, lifetimes, and emittances. We also attempted two special collider stores with only 3 proton bunches colliding with 3 antiproton bunches, to suppress long-range forces and enhance head-on effects. We present here the results of this study and a comparison between numerical simulations and observations, in view of the planned application of this compensation concept to RHIC.
Date: March 1, 2011
Creator: Valishev, A. & Stancari, G.
Partner: UNT Libraries Government Documents Department


Description: Accurate alignment of the electron and ion beams in the RHIC electron cooling solenoids is crucial for well-optimized cooling. Because of the greatly differing rigidities of the electron and ion beams, to achieve the specified alignment accuracy it is required that transverse magnetic fields resulting from imperfections in solenoid fabrication be down by five orders of magnitude relative to the pure solenoid fields. Shimming the solenoid field to this accuracy might be accomplished by survey techniques prior to operation with beam, or by methods of beam-based alignment. We report on the details of a method of beam-based alignment, as well as the results of preliminary measurements with the ion beam at RHIC.
Date: May 16, 2005
Creator: CAMERON, P.; BEN-ZVI, I.; DAWSON, W. C. & AL., ET
Partner: UNT Libraries Government Documents Department


Description: Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-gaussian beams. Here we report the effect of low-frequency random tune modulations on diffusion in double-gaussian beams and compare the effects to those in beam-beam interactions with regular gaussian beams and identical tune shift parameters.
Date: May 16, 2005
Partner: UNT Libraries Government Documents Department


Description: An R&D facility for an Energy Recovery Linac (ERL) intended as part of an electron-cooling project for RHIC is, being constructed at this laboratory. The center piece of the facility is a 5-cell 703.75 MHz super-conducting RF linac. Successful operation will depend on effective HOM damping. It is planned to achieve HOM damping exclusively with ferrite absorbers. The performance of a prototype absorber was measured by transforming it into a resonant cavity and alternatively by a conventional wire method. The results expressed as a surface or R-square impedance are presented in this paper.
Date: July 10, 2005
Partner: UNT Libraries Government Documents Department