138 Matching Results

Search Results

Advanced search parameters have been applied.


Description: An electromagnetic search for magnetic monopoles of the minimum size predicted by Dirac, or of any larger magnitude, has been performed on 8.37 kilograms of lunar surface material returned by the Apollo 11 crew. No monopole was found. This experiment sets new limits on the production cross section for monopoles, and on their occurrence in cosmic radiation.
Date: December 1, 1969
Creator: Alvarez, Luis W.; Eberhard, Philippe H.; Ross, Ronald R. & Watt,Robert D.
Partner: UNT Libraries Government Documents Department

New new-phenomena results from D-Zero

Description: We have searched for diphoton events ({gamma}{gamma} /E{sub T}) with large missing transverse momentum, {gamma} /E{sub T} events ({gamma} /E{sub T}+{ge} 2 jets) with two or more jets, and diphoton events ({gamma}{gamma}) with high transverse energies in p{anti p} collisions at {radical}s = 1.8 TeV using approximately 100 pb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron in 1992-1996. No excess of events beyond the expected backgrounds is observed. The null results are interpreted in supersymmetric models with a dominant {tilde {xi}}{sup 0}{sub 2} {yields} {gamma}{tilde {xi}}{sup 0}{sub 1} decay and in terms of Dirac pointlike monopole production.
Date: June 1, 1998
Creator: Qian, J.
Partner: UNT Libraries Government Documents Department

Search for Monopoles Above the 15-Foot Bubble Chamber

Description: Magnetic monopoles having energies less than about 40 TeV will be slowed to their terminal velocity by the earth's atmosphere. They may then be gathered by the fringing magnetic field of the 15-foot bubble chamber. We propose placing detectors of Lexan and nuclear emulsion at convenient locations above and below the bubble chamber. Such a systom would be sensitive to monopole masses between 10 GeV and 100 TeV and to monopole charges between {approx}0.7 and 10 hc/2e. The experiment would require the construction of a special light roof and would run for 5 weeks during a time when the bubble chamber is filled with air and not in use for other experiments. This study would lower the existing limit on in-flight detection of monopoles (at the earth's surface) by a factor of 20.
Date: January 1, 1976
Creator: Bartlett, D.F.; Soo, Daniel; U., /Colorado; Fleischer, Robert L.; Hart Jr., Howard R.; Mogro-Campero, Antonio et al.
Partner: UNT Libraries Government Documents Department

Proposal for a search for magnetic monopoles at NAL

Description: The discovery of a magnetic monopole would be an important experimental result. It would give a reason for the phenomenon of exact electric charge quantization that is not explained yet any other way. Schwinger's dyon theory makes monopoles even more important because they would also be the quarks, i.e., the building blocks of the hadrons. Schwinger's scheme requires the electric charge of the monopoles to be a multiple of 1/3 of the electron charge while all magnetically neutral particles must have electric charges equal to an integer times the electron charge. Monopoles would be also responsible for CP violations.
Date: May 1, 1970
Creator: Alvarez, L.W.; Eberhard, P.H.; Ross, R.R.; /LBL, Berkeley; Watt, R.D. & /SLAC
Partner: UNT Libraries Government Documents Department

Cosmological and astrophysical implications of magnetic monopoles

Description: Among Dirac's many contributions to modern physics is the idea that charge quantization is natural in a theory with magnetic monopoles. The existence of magnetic monopoles would have drastic effects on the evolution of the universe, on galactic magnetic fields, and perhaps on the x-ray luminosity of neutron stars. Some astrophysical implications of massive magnetic monopoles are reviewed here.
Date: March 11, 1983
Creator: Kolb, E.W.
Partner: UNT Libraries Government Documents Department

Angular Dependence of Jet Quenching Indicates Its Strong Enhancement Near the QCD Phase Transition

Description: We study dependence of jet quenching on matter density, using 'tomography' of the fireball provided by RHIC data on azimuthal anisotropy v{sub 2} of high p{sub t} hadron yield at different centralities. Slicing the fireball into shells with constant (entropy) density, we derive a 'layer-wise geometrical limit' v{sub 2}{sup max} which is indeed above the data v{sub 2} < v{sub x}{sup max}. Interestingly, the limit is reached only if quenching is dominated by shells with the entropy density exactly in the near-T{sub c} region. We show two models that simultaneously describe the high p{sub t} v{sub 2} and R{sub AA} data and conclude that such a description can be achieved only if the jet quenching is few times stronger in the near-T{sub c} region relative to QGP at T > T{sub c}. One possible reason for that may be recent indications that the near-T{sub c} region is a magnetic plasma of relatively light color-magnetic monopoles.
Date: October 22, 2008
Creator: Liao, Jinfeng & Shuryak, Edward
Partner: UNT Libraries Government Documents Department

High Precision Superconducting Cavity Diagnostics With Higher Order Mode Measurements

Description: Experiments at the FLASH facility at DESY have demonstrated that the higher order modes induced in superconducting cavities can be used to provide a variety of beam and cavity diagnostics. The axes of the modes can be determined from the beam orbit that produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used to obtain high resolution beam position information, and the phase of the monopole modes to measure the beam phase relative to the accelerator rf. For most superconducting accelerators, the existing higher order mode couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional beam position monitor.
Date: February 12, 2007
Creator: Molloy, S.; Frisch, J.; McCormick, D.; May, J.; Ross, M.; Smith, T. et al.
Partner: UNT Libraries Government Documents Department

Low-Beta Structure for High Energy Part of Project X

Description: Long 11-cell, {beta} = 0.81 L-band structure is considered as an initial stage of the high-energy part of the Project-X in order to accommodate to a standard Type-4 cryomodule. The cavity shape is optimized for maximal energy gain providing the same time field flatness along the structure not worse than for ILC {beta} = 1 cavity, and the same ratio of surface magnetic field to electric field. The results of spectrum analysis for monopole and dipole HOMs is presented as well.
Date: May 1, 2009
Creator: Solyak, N.; Gonin, I.; Yakovlev, V.; /Fermilab; Drozdov, I.; Perunov, N. et al.
Partner: UNT Libraries Government Documents Department

Copper Prototype Measurements of the HOM, LOM and SOM Couplers for the ILC Crab Cavity

Description: The ILC Crab Cavity is positioned close to the IP and delivered luminosity is very sensitive to the wakefields induced in it by the beam. A set of couplers were designed to couple to and damp the spurious modes of the crab cavity. As the crab cavity operates using a dipole mode, it has different damping requirements from an accelerating cavity. A separate coupler is required for the monopole modes below the operating frequency of 3.9 GHz (known as the LOMs), the opposite polarization of the operating mode (the SOM), and the modes above the operating frequency (the HOMs). Prototypes of each of these couplers have been manufactured out of copper and measured attached to an aluminum nine cell prototype of the cavity and their external Q factors were measured. The results were found to agree well with numerical simulations.
Date: June 23, 2008
Creator: Burt, G.; Ambattu, P.K.; Dexter, A.C.; U., /Lancaster; Bellantoni, L.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Confinement and flavor symmetry breaking via monopolecondensation

Description: We discuss dynamics of N=2 supersymmetric SU(n_c) gaugetheories with n_f quark hypermultiplets. Upon N=1 perturbation ofintroducing a finite mass for the adjoint chiral multiplet, we show thatthe flavor U(n_f) symmetry is dynamically broken to U(r) times U(n_f-r),where r\leq [n_f/2]is an integer. This flavor symmetry breaking occursdue to the condensates of magnetic degrees of freedom which acquireflavor quantum numbers due to the quark zero modes. We briefly comment onthe USp(2n_c) gauge theories. This talk is based on works with GiuseppeCarlino and Ken Konishi, hep-th/0001036 and hep-th/0005076.
Date: September 19, 2000
Creator: Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

Transition energy correlations in the three-body continuum of Borromean halo nuclei

Description: Energy correlations in transitions from the bound state to the three-body continuum of Borromean halo nuclei are considered. A core+n+n three-body cluster model which reproduces experimentally known properties of {sup 6}He and {sup 11}Li has been used to study low-lying resonances and soft modes. The analysis of the correlated responses in {sup 6}He shows that in the case of the narrow three-body 2{sub 1}{sup +} resonance the transition energy correlations are the same as in the intrinsic correlated structure in 3 {yields} 3 scattering. They differ significantly for wide 2{sub 2}{sup +}, 1{sub 1}{sup +} resonances, and also for the soft dipole and monopole modes, where, due to the transition operators, the intertwining of the ground state and the three-body continuum plays a significant role.
Date: June 5, 2007
Creator: Danilin, B V; Vaagen, J S; Rogde, T; Ershov, S N; Thompson, I J & Zhukov, M V
Partner: UNT Libraries Government Documents Department


Description: Condensed phase physical and chemical processes generally involve interactions covering a wide range of distance scales, from short-range molecular interactions requiring orbital overlap to long-range coulombic interaction between local sites of excess charge (positive or negative monopoles). Intermediate-range distances pertain to higher-order multipolar as well as inductive and dispersion interactions. Efforts to model such condensed phase phenomena typically involve a multi-tiered strategy in which quantum mechanics is employed for full electronic structural characterization of a site of primary interest (e.g., a molecular solute or cluster), while more remote sites are treated at various classical limits (e.g., a molecular force field for discrete solvent molecules or a dielectric continuum (DC) model, if the solute is charged or has permanent multipole moments). In particular, DC models have been immensely valuable in modeling chemical reactivity and spectroscopy in media of variable polarity. Simple DC models account qualitatively for many important trends in the solvent dependence of reaction free energies, activation free energies, and optical excitation energies, and many results of semiquantitative or fully quantitative significance in comparison with experiment have been obtained, especially when detailed quantum chemical treatment of the solute is combined self consistently with DC treatment of the solvent (e.g., as in the currently popular PCM (polarized continuum model) approaches).
Date: November 1, 2006
Creator: NEWTON, M.D.
Partner: UNT Libraries Government Documents Department

A high resolution cavity BPM for the CLIC Test Facility

Description: In frame of the development of a high resolution BPM system for the CLIC Main Linac we present the design of a cavity BPM prototype. It consists of a waveguide loaded dipole mode resonator and a monopole mode reference cavity, both operating at 15 GHz, to be compatible with the bunch frequencies at the CLIC Test Facility. Requirements, design concept, numerical analysis, and practical considerations are discussed.
Date: August 1, 2010
Creator: Chritin, N.; Schmickler, H.; Soby, L.; /CERN; Lunin, A.; Solyak, N. et al.
Partner: UNT Libraries Government Documents Department

Status of searches for magnetic monopoles

Description: The recent experiment reporting the discovery of a monopole is compared to the negative experiments performed previously. The different determinations of the flux of monopoles are contradictory. It is likely that the event reported as a monopole may be given another interpretation. (auth)
Date: October 1, 1975
Creator: Eberhard, P.
Partner: UNT Libraries Government Documents Department

Nonabelian Monopoles

Description: We study topological as well as dynamical properties of BPS nonabelian magnetic monopoles of Goddard-Nuyts-Olive-Weinberg type in $ G=SU(N)$, $USp(2N)$ and SO(N) gauge theories, spontaneously broken to nonabelian subgroups $H$. We find that monopoles transform under the group dual to $H$ in a tensor representation of rank determined by the corresponding element in $\pi_1(H)$. When the system is embedded in a $\cal N=2$ supersymmetric theory with an appropriate set of flavors with appropriate bare masses, the BPS monopoles constructed semiclassically persist in the full quantum theory. This result supports the identification of"dual quarks'' found at $r$-vacua of $\cal N=2$ theories with the nonabelian magnetic monopoles. We present several consistency checks of our monopole spectra.
Date: June 23, 2004
Creator: Auzzi, Roberto; Bolognesi, Stefano; Evslin, Jarah; Konishi, Kenichi & Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

Excitation of simple atoms by slow magnetic monopoles

Description: We present a theory of excitation of simple atoms by slow moving massive monopoles. Previously presented results for a monopole of Dirac strength on hydrogen and helium are reviewed. The hydrogen theory is extended to include arbitrary integral multiples of the Dirac pole strength. The excitation of helium by double strength poles and by dyons is also discussed. It is concluded that a helium proportional counter is a reliable and effective detector for monopoles of arbitrary strength, and for negatively charged dyons.
Date: January 1, 1984
Creator: Kroll, N.M.; Parke, S.J.; Ganapathi, V. & Drell, S.D.
Partner: UNT Libraries Government Documents Department

Magnetic charge and non-associative algebras

Description: We consider the possibility that the quantum mechanics of a nonrelativistic electron in the magnetic field of a magnetic charge distribution can be described in terms of a non-associative algebra of observables. It appears that the case of a point monopole is excluded, while that of a constant charge distribution is acceptable. 21 references.
Date: February 1, 1985
Creator: Guenaydin, M. & Zumino, B.
Partner: UNT Libraries Government Documents Department

Symplectic structure of isospin particles in Yang-Mills fields

Description: Using Dirac's constraint analysis, we explore the Hamiltonian formalism of isospin particles in external Yang-Mills fields without kinetic and potential energy term. We consider an example of isospin particle in 't Hooft-Polyakov magnetic monopole field and discuss possible quantization condition of magnetic charge in terms of geometric quantization.
Date: January 1, 1992
Creator: Oh, P.
Partner: UNT Libraries Government Documents Department

Possible significance of a new dimensionless ratio in cosmology

Description: Observations suggest that the mass density of the Universe is dominated, not by ordinary matter, but by exotic particles which are a relic of the Big Bang. In this case, a new dimensionless cosmological ratio arises, the ratio of the mass density in ordinary matter to that in exotic matter, whose value is about 0.1. A priori it might seem remarkable that this ratio should be so close to unity. However, we point out that, for many exotic dark matter candidates, the ratio is related to the fundamental scales of particle physics. A value of order unity arises naturally providing rather simple relationships exist between these scales.
Date: May 1, 1986
Creator: Turner, M.S. & Carr, B.J.
Partner: UNT Libraries Government Documents Department

Parker limit for monopoles with large magnetic charge

Description: The survival of galactic magnetic fields places a limit on the flux of magnetic monopoles, the so-called ''Parker limit.'' Previous discussions of the Parker limit have assumed that the charge of the monopole is the Dirac value, g/sub Dirac/ = 2..pi../e. However, if the grand unified group is broken by Wilson lines, as is assumed in some superstring models, the minimum value of the magnetic charge is not the Dirac quantum, but an integer multiple of it. In this brief report we investigate the dependence of the Parker limit on the charge of the magnetic monopole. 10 refs., 1 fig.
Date: April 28, 1986
Creator: Hodges, H.M.; Kolb, E.W. & Turner, M.S.
Partner: UNT Libraries Government Documents Department