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Acccelerator Physics Issues of a Very Large Hadron Collider

Description: A Very Large Hadron Collider (VLHC) was proposed for the post-LHC future. This paper gives a quick survey of a number of accelerator physics issues based on the information obtained from a parameter spreadsheet SSP. The main technical challenges to build such a machine appear to be: the large number of events per crossing (in hundreds), enormous beam stored energy (equivalent to tens tons of TNT), ground motion (which is particularly harmful when the synchrotron frequency is in the sub-Hertz range), small dynamic aperture (due to long filling time), fast growth of the resistive wall instability (in a fraction of one turn), low threshold of the single bunch transverse instability (due to big machine size), strong synchrotron radiation (at a level close to the LEP) and short radiation damage lifetime, etc. Possible solutions to some of these problems will also be discussed.
Date: June 1, 1997
Creator: Chou, W.
Partner: UNT Libraries Government Documents Department

Flip-Flop Modes in Symmetric and Asymmetric Colliding-Beam Storage Rings

Description: A model of self-consistent beam blow-up in a colliding beam storage ring is described which explains the appearance of flip-flop modes in both symmetric and asymmetric beam systems. It derives the strong-strong steady-states and their stabilities from the weak-strong behavior. This model agrees well with the observed flip-flop behavior in storage rings, including the hysteresis seen when the beams are flipped from one asymmetric steady state to the other. It can be used to predict the behavior of proposed facilities in which the two colliding beams are characterized by different parameters.
Date: August 1, 1989
Creator: Tennyson, J.L.
Partner: UNT Libraries Government Documents Department

Beam stability issues of 3 TeV low-field collider

Description: We analyze the stability issues of the 3 TeV low-field collider. Some relevant properties of the collider are listed in Table 1. In the table, the rms bunch length of {sigma}{sub l}=0.50 m and bunch area of A=1.50 eV-s at injection are extraction values from the Main Injector. At extraction of this 3 TeV ring, we assume the bunch area to be the same, but the rf voltage has been cranked up to V{sub rf} 4.00 MV.
Date: August 1, 1998
Creator: K.-Y., Ng, FNAL
Partner: UNT Libraries Government Documents Department

Interaction of a coasting beam and a bunched beam with frequency slip

Description: Collisions between a coasting beam and a bunched beam can be so arranged that a particle in the coasting beam collides with the bunched beam only intermittently. A particle thus interacts with a bunch for a given number of revolutions, say q, and then slips away into the interbunch space. The process, with each cycle taking say, n revolutions, then continues. The possible effects of this intermittient type force are considered. The linear stopbands introduced are dealt with in detail. Growth rates are obtained as a function of q, assuming a Gaussian fall-off in the force. The stabilizing influence of an azimuthally constant octupole field component is demonstrated. Isolated nonlinear resonances excited by the intermittent force are discussed. No quantitative treatment is given as far as concerns the stochastic nature of highly nonlinear systems. Also, the influence of feeding mechanisms, such as a time variation of the tune is neglected. If the number of revolutions between kicks, ~n is large, then there is the possibility of loss of correlation betveen kicks. The resulting diffusion is analyzed and diffusion rates are estimated. It was concluded that: (1) growth due to linear instabilities are effectively damped by making q large enough. The perturbation is turned on and off adiabatically and leaves no record of itself from cycle to cycle. The growth rate is linear in DELTA the beam-- beam linear tune shift per interaction and per revolution; (2) the diffusion induced by random processes causing the kicks to be uncorrelated produces a bearm growth rate which is quadratic in DELTA nu . Although it is smaller than the gradient stopband growth (for low q), it is essentially independent of tune (and so occurs for all particles) and it has no drop-off with q. In fact, for large q, it increases like q/sup ...
Date: January 1, 1973
Creator: Month, M. & Ruggiero, A.G.
Partner: UNT Libraries Government Documents Department

Simulation Studies of Beam-Beam Effects of a Ring-Ring Electron-Ion Collider Based on CEBAF

Description: The collective beam-beam effect can potentially cause a rapid growth of beam sizes and reduce the luminosity of a collider to an unacceptably low level. The ELIC, a proposed ultra high luminosity electron-ion collider based on CEBAF, employs high repetition rate crab crossing colliding beams with very small bunch transverse sizes and very short bunch lengths, and collides them at up to 4 interaction points with strong final focusing. All of these features can make the beam-beam effect challenging. In this paper, we present simulation studies of the beam-beam effect in ELIC using a self-consistent strong-strong beam-beam simulation code developed at Lawrence Berkeley National Laboratory. This simulation study is used for validating the ELIC design and for searching for an optimal parameter set.
Date: May 1, 2009
Creator: Yuhong Zhang,Ji Qiang
Partner: UNT Libraries Government Documents Department

Simulations of High Disruption Colliding Beams

Description: Recent B-factory proposals taht use a linac beam colliding with the beam from a storage ring to achieve high luminosities (L > 10^34 cm^-2 sec^-1) result in very high disruption of the linac beam.The effects of such high disruption have been studied using the relativistic, 3-D code SWARM.We discuss the assumptions, parameters, and results of a series of runs that model such collisions.Regimes of high beam loss and methods to avoid them are also discussed.
Date: September 1, 1990
Creator: Krafft, Geoffrey & Boyce, James
Partner: UNT Libraries Government Documents Department


Description: At large distances the electromagnetic field of a wire is the same as the field produced by a bunch. Such a long-range beam-beam wire compensator was proposed for the LHC, and single beam tests with wire compensators were successfully done in the SPS. RHIC offers the possibility to test the compensation scheme with colliding beams. We report on measurements of beam losses as a function of transverse separation in RHIC at 100 GeV, and comparisons with simulations. We present a design for a long-range wire compensator in RHIC.
Date: June 23, 2006
Partner: UNT Libraries Government Documents Department


Description: Previously it was shown that by crystallizing each of the two counter-circulating beams, a much larger beam-beam tune shift can be tolerated during the beam-beam collisions; thus a higher luminosity can be reached for colliding beams [1]. On the other hand, crystalline beams can only be formed at energies below the transition energy ({gamma}{sub T}) of the accelerators [2]. In this paper, we investigate the formation of crystals in a high-{gamma}{sub T} lattice that also satisfies the maintenance condition for a crystalline beam [3].
Date: June 23, 2006
Partner: UNT Libraries Government Documents Department

Future high energy colliders symposium. Summary report

Description: A `Future High Energy Colliders` Symposium was held October 21-25, 1996 at the Institute for Theoretical Physics (ITP) in Santa Barbara. This was one of the 3 symposia hosted by the ITP and supported by its sponsor, the National Science Foundation, as part of a 5 month program on `New Ideas for Particle Accelerators`. The long term program and symposia were organized and coordinated by Dr. Zohreh Parsa of Brookhaven National Laboratory/ITP. The purpose of the symposium was to discuss the future direction of high energy physics by bringing together leaders from the theoretical, experimental and accelerator physics communities. Their talks provided personal perspectives on the physics objectives and the technology demands of future high energy colliders. Collectively, they formed a vision for where the field should be heading and how it might best reach its objectives.
Date: December 31, 1996
Creator: Parsa, Z.
Partner: UNT Libraries Government Documents Department

Supersymmetric Higgs Boson Pair Production: Discovery Prospects at Hadron Colliders

Description: We study the potential of hadron colliders in the search for the pair production of neutral Higgs bosons in the framework of the Minimal Supersymmetric Standard Model. We perform a detailed signal and background analysis, working out efficient kinematical cuts for the extraction of the signal. The important role of squark loop contributions to the signal is re-emphasized. If the signal is sufficiently enhanced by these contributions, it could even be observable at the next run of the upgraded Tevatron collider in the near future. At the LHC the pair production of light and heavy Higgs bosons might be detectable simultaneously.
Date: September 15, 1999
Creator: Mizukoahi, Jose K.
Partner: UNT Libraries Government Documents Department

The Very Large Hadron Collider

Description: I present some of the current ideas about a Very Large Hadron Collider [1] which could eventually extend the high energy frontier beyond that of the Large Hadron Collider (LHC) or any other machine seriously conceived at this time.
Date: February 16, 1999
Creator: Albrow, Michael G.
Partner: UNT Libraries Government Documents Department

A high energy physics perspective

Description: The status of the Standard model and role of symmetry in its development are reviewed. Some outstanding problems are surveyed and possible solutions in the form of additional {open_quotes}Hidden Symmetries {close_quotes} are discussed. Experimental approaches to uncover {open_quotes}New Physics{close_quotes} associated with those symmetries are described with emphasis on high energy colliders. An outlook for the future is given.
Date: January 13, 1997
Creator: Marciano, W. J.
Partner: UNT Libraries Government Documents Department

Muon Collider: Muon Generation, Capture and Cooling

Description: A {mu}{sup +} -{mu}{sup -} collider requires a high-intensity proton source for {pi}-production, a high-acceptance {pi}-{mu} decay channel, a {mu}-cooling system, a rapid acceleration system, and a high-luminosity collider ring for the collision of short, intense {mu}{sup +} -{mu}{sup -} bunches. Critical problems exist in developing and compressing high-energy proton bunches for producing {pi}�s, in capturing {pi}�s and their decay {mu}�s, and in cooling {mu}�s into a compressed phase-space at which high luminosity collisions are possible. These problems and some possible solutions are discussed; the current {mu}{sup +} -{mu}{sup -} collider research program is described
Date: February 16, 1999
Creator: Neuffer, David
Partner: UNT Libraries Government Documents Department

Precsion Supersymmetry Measurement at the e{minus} e{minus} Collider

Description: Measurements of supersymmetric particle couplings provide important verification of supersymmetry. If some of the superpartners are at the multi-TeV scale, they will escape direct detection at planned future colliders. However, such particles induce nondecoupling corrections in processes involving the accessible superparticles through violations of the supersymmetric equivalence between gauge boson and gaugino couplings. These violations are analogous to the oblique corrections in the electroweak sector of the standard model, and can be parametrized in terms of super-oblique parameters. The e{sup -}e{sup -} collision mode of a future linear collider is shown to be an excellent environment for such high precision measurements of these SUSY parameters, which will provide an important probe of superparticles beyond reachable energies.
Date: January 1, 1998
Creator: Cheng, H.-C.
Partner: UNT Libraries Government Documents Department

50x50 GeV Muon Collider Beam Collimation

Description: A summary of different techniques and systems to scrape beam halo in a 50 x 50 GeV {mu}{sup +}{mu}{sup -} collider is presented. Such systems are installed in a special utility section with optics specifically designed to meet both the requirements of the scraping system and of injection. Results froma realistic Monte Carlo simulation (STRUCT-MARS) show that a system consisting of steel absorbers several meters in length suppresses halo-induced backgrounds in the collider detector by more than three orders of magnitude. The heat load in superconducting magnets near the scraper system can be reduced to tolerable levels by appropriate collimator design and location. This reduction applies to both injection and collider mode of operation. Also discussed is extraction of halo particles using electrostatic deflectors and bent crys-tals, although neither appears to be effective for a muon collider at this energy.
Date: April 14, 1999
Creator: Drozhdin, A. I.; Johnstone, C. J.; Mokhov, N. V.; Garen, A. A. & Biryukov, V. M.
Partner: UNT Libraries Government Documents Department

Flavor and CP violations from sleptons at the Muon Collider

Description: Supersymmetric theories generally have new flavor and CP violation sources in the squark and slepton mass matrices. They will contribute to the lepton flavor violation processes, such as {mu}{yields}e{gamma}, which can be probed far below the current bound with an intense muon source at the front end of the muon collider. In addition, if sleptons can be produced at the muon collider, the flavor violation can occur at their production and decay, allowing us to probe the flavor mixing structure directly. Asymmetry between numbers of {mu}{sup +}e{sup -} and e{sup +}{mu}{sup -} events will be a sign for CP violation in supersymmetric flavor mixing.
Date: December 1, 1997
Creator: Cheng, H.-C.
Partner: UNT Libraries Government Documents Department

Compositeness test at the FMC with Bhabha scattering

Description: It is possible that quarks and/or leptons have substructure that will become manifest at high energies. Here we investigate the limits on the muon compositeness scale that could be obtained at the First Muon Collider using Bhabha scattering. We study this limit as a function of the collider energy and the angular cut imposed by the detector capability.
Date: January 1, 1998
Creator: Eichten, E.J. & Keller, S.
Partner: UNT Libraries Government Documents Department

Beam instabilities in very large hadron collider

Description: The Very Large Hadron Collider (VLHC) is a supercon-ducting proton-proton collider with approximately 100 TeV cm and approximately 10{sup 34} s{sup -1}cm{sup -2} luminosity [1]. Currently, beam dynamics in this future accelerator is the subject of intensive studies within the framework of the US-wide VLHC R&D program. This presentation sum-marizes recent developments in the field. Besides general discussion on relevant VLHC parameters, we consider various beam instabilities and ways to avoid them. Finally, we outline possibilities for theoretical and experimental R&D.
Date: May 11, 1999
Creator: Marriner, J.; Danilov, V. & Shiltsev, V.
Partner: UNT Libraries Government Documents Department

Measurement of sin {sup 2}{Theta}{sub W} at the First Muon Collider

Description: This report summarizes the study of the possibility of measuring sin{sup 2}{theta}{sub W} using the intense neutrino beam expected from the straight sections of the First Muon Collider ring. This study is based on realistic error calculations from the CCFR and the NuTeV experiments. Using a neutrino detector that is capable of identifying and distinguishing electrons and muons, along with a light isoscalar target, it is conceivable to measure sin{sup 2}{theta}{sub W} to the precision equivalent to the W mass uncertainty (experimental) of 30 MeV.
Date: January 1, 1998
Creator: Yu, J. & Kotwal, A.V.
Partner: UNT Libraries Government Documents Department

Next to leading order three jet production at hadron colliders

Description: I present results from a next-to-leading order event generator of purely gluonic jet production. This calculation is the first step in the construction of a full next-to-leading order calculation of three jet production at hadron colliders. Several jet algorithms commonly used in experiments are implemented and their numerical stability is investigated. A numerical instability is found in the iterative cone algorithm which makes it inappropriate for use in fixed order calculations beyond leading order.
Date: May 1, 1997
Creator: Kilgore, W.B.
Partner: UNT Libraries Government Documents Department

Muon Collider Overview: Progress and Future Plans

Description: Besides continued work on the parameters of a 3-4 and 0.5 TeV center of mass (COM) collider, many studies are now concentrating on a machine near 100 GeV (COM) that could be a factory for the s-channel production of Higgs particles. We mention the research on the various com- ponents in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z tar- get and proceeding through the phase rotation and decay ({pi}{yields}{mu}{nu}<sub>{mu}</sub>) channel, muon cooling, acceleration storage in a collider ring and the collider detector. We also men- tion theoretical and experimental R & D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This note is a summary of a report[l] updating the progress on the R & D since the Feasibility Study of Muon Colliders presented at the Workshop Snowmass'96.[2]
Date: June 1, 1998
Creator: Gallardo, J.; Palmer, R.; Sessler, A. & Tollestrup, A.
Partner: UNT Libraries Government Documents Department