3,488 Matching Results

Search Results

Advanced search parameters have been applied.

Passage through a TM slab

Description: The purpose of this short note is to derive the simple but remarkable result that the tranverse impulse given to a particle passing through a \slab" of homo- geneous, stationary, transverse magnetic #12;eld depends only on the properties of the slab and the particle's charge, and not at all on its initial state or its mass.
Date: October 1, 1998
Creator: Michelotti, Leo
Partner: UNT Libraries Government Documents Department


Description: References to accelerators and accelerator technology in the technical literature from July 1954 through June 1957 are listed in Section 1, the bibliography. Most of the references are taken from Nuclear Science Abstracts, Chemical Abstracts, Physics Abstracts, and Electrical Engineering Abstracts. In Section H, accelerator installations throughout the world are listed together with the types of particles accelerated and the energy and other characteristics of the machines. (auth)
Date: January 1, 1958
Creator: Behman, G.A.
Partner: UNT Libraries Government Documents Department

System-size independence of directed flow at the RelativisticHeavy-Ion Collider

Description: We measure directed flow (v{sub 1}) for charged particles in Au + Au and Cu + Cu collisions at {radical}s{sub NN} = 200 GeV and 62.4 GeV, as a function of pseudorapidity ({eta}), transverse momentum (p{sub t}) and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to v{sub 1} in different collision systems, and investigate possible explanations for the observed sign change in v{sub 1}(p{sub t}).
Date: September 20, 2008
Creator: Coll, STAR
Partner: UNT Libraries Government Documents Department

Centroid and Envelope Dynamics of High-intensity Charged Particle Beams in an External Focusing Lattice and Oscillating Wobbler

Description: The centroid and envelope dynamics of a high-intensity charged particle beam are investigated as a beam smoothing technique to achieve uniform illumination over a suitably chosen region of the target for applications to ion-beam-driven high energy density physics and heavy ion fusion. The motion of the beam centroid projected onto the target follows a smooth pattern to achieve the desired illumination, for improved stability properties during the beam-target interaction. The centroid dynamics is controlled by an oscillating "wobbler", a set of electrically-biased plates driven by RF voltage. __________________________________________________
Date: April 28, 2010
Creator: Qin, Hong; Davidson, Ronald C. & Logan, B. Grant
Partner: UNT Libraries Government Documents Department

Particle acceleration from reconnection in the geomagnetic tail

Description: Acceleration of charged particles in the near geomagnetic tail, associated with a dynamic magnetic reconnection process, was investigated by a combined effort of data analysis, using Los Alamos data from geosynchronous orbit, MHD modeling of the dynamic evolution of the magnetotail, and test particle tracing in the electric and magnetic fields obtained from the MHD simulation.
Date: August 1, 1997
Creator: Birn, J.; Borovsky, J.E.; Thomsen, M.F.; McComas, D.J.; Reeves, G.D.; Belian, R.D. et al.
Partner: UNT Libraries Government Documents Department


Description: BS>A previous calculation of the rate of diffusion of like charged particles across a magnetic field is generalized. No "a priori" assumption as to the relative magnitude of certain terms need be made and spatial density gradients are permitted in both directions perpendicular to the field. The final result agrees with that given earlier. (auth)
Date: November 27, 1959
Creator: Isihara, A. & Simon, A.
Partner: UNT Libraries Government Documents Department

Investigation of Beam Instability Under the Effects of Long-Range Transverse Wake Fields in the Berkeley Future Light Source

Description: An ultra-relativistic charged particle bunch moving through a resonator cavity leaves behind a wake field that will affect subsequent bunches (if the bunch is not ultra-relativistic, the wake field will not be exclusively behind it). If the initial bunch enters the cavity off-axis, it will produce a transverse wake field that can then kick later bunches off the axis. Thus, even bunches that were initially traveling on axis could be displaced and, in turn, produce their own transverse wake fields, affecting following bunches. The offsets obtained by bunches could increase along the bunch train, leading to the so-called multi-bunch beam break-up instability [1]. The purpose of our investigation is to see whether such instability will occur in the superconducting, 1.3 GHz, 2.5GeV linac (see Table 1) planned for the Berkeley future light source (BFLS). We assume an initial steady-state situation established for machine operation; i.e. a continuous process where every bunch follows the same trajectory through the linac, with only small deviations from the axis of the rf structures. We will look at a possible instability arising from a bunch having a small deviation from the established trajectory. Such a deviation would produce a wake field that is slightly different from the one produced by the bunches following the established trajectory. This could lead to subsequent bunches deviating further from the established trajectory. We will assume the deviations are small (at first) and so the difference in the wake field caused by a bunch not traveling along the established trajectory is well approximated by a long-range transverse dipole wake. We are concerned only with deviations from the established trajectory; thus, in our models, a transverse position of zero corresponds to the bunch traveling along the established trajectory. Under this assumption, only the additional long-range transverse dipole wake remains in our ...
Date: August 31, 2008
Creator: Kur, Eugene & Zholents, Alexander A.
Partner: UNT Libraries Government Documents Department

The Low-Energy State ofCirculating Stored Ion Beams: Crystalline Beams

Description: Molecular dynamics is employed to study the low energy states of a beam of charged particles subject to circumferentially varying guiding and focusing forces and with Coulomb forces between the particles. In a constant gradient ring, the lowest energy state is never ordered, but in an alternating gradient structure, operating below the transition energy, the lowest state is ordered. The nature and characteristics of the ground state depends upon the beam density and the ring parameters. For zero temperature the crystal remains intact for a very long time, but at nonzero temperatures it gains energy from the lattice. A critical temperature exists above which the crystal melts rapidly.
Date: March 10, 1994
Creator: Wei, J.; Li, X.-P. & Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department

Track Fitting in an Inhomogeneous Magnetic Field

Description: We describe an efficient method of track fitting for charged particles moving in an arbitrary inhomogeneous magnetic field.The method is a least-squares fit in 3-dimensional space which assumes local field uniformity to approximate the orbit as a set of linked helical segments.We propagate the orbit and error matrix in order to calculate the residuals and their derivatives analytically at the position of the hit wires.The accuracy of the method depends only on the step size of the linked helical segments.The fit converges rapidly to the point of minimum Chi^2; one needs only a few iterations even for poor starting values of track parameters.
Date: May 1, 1991
Creator: Niczyporuk, Bogdan
Partner: UNT Libraries Government Documents Department

IceCube: A Cubic Kilometer Radiation Detector

Description: IceCube is a 1 km{sup 3} neutrino detector now being built at the Amudsen-Scott South Pole Station. It consists of 4800 Digital Optical Modules (DOMs) which detect Cherenkov radiation from the charged particles produced in neutrino interactions. IceCube will observe astrophysical neutrinos with energies above about 100 GeV. IceCube will be able to separate {nu}{sub {mu}}, {nu}{sub t}, and {nu}{sub {tau}} interactions because of their different topologies. IceCube construction is currently 50% complete.
Date: June 1, 2008
Creator: Collaboration, IceCube; Klein, Spencer R & Klein, S.R.
Partner: UNT Libraries Government Documents Department

Alignment strategy for the ATLAS tracker

Description: The ATLAS experiment is a multi-purpose particle detector that will study high-energy particle collisions produced by the Large Hadron Collider. For the reconstruction of charged particles, and their production and their decay vertices, ATLAS is equipped with a sophisticated tracking system, unprecedented in size and complexity. Full exploitation of both the Inner Detector and the muon spectrometer requires an accurate alignment. The challenge of aligning the ATLAS tracking devices is discussed, and the ATLAS alignment strategy is presented and illustrated with both data and Monte Carlo results.
Date: September 23, 2007
Creator: ATLAS & Golling, T.
Partner: UNT Libraries Government Documents Department

Guiding Center Equations of High Accuracy

Description: Guiding center simulations are an important means of predicting the effect of resistive and ideal magnetohydrodynamic instabilities on particle distributions in toroidal magnetically confined thermonuclear fusion research devices. Because saturated instabilities typically have amplitudes of δ#14;B/B of a few times 10-4 numerical accuracy is of concern in discovering the effect of mode particle resonances. We develop a means of following guiding center orbits which is greatly superior to the methods currently in use. In the presence of ripple or time dependent magnetic perturbations both energy and canonical momentum are conserved to better than one part in 1014, and the relation between changes in canonical momentum and energy is also conserved to very high order.
Date: March 29, 2013
Creator: R.B. White, G. Spizzo and M. Gobbin
Partner: UNT Libraries Government Documents Department

Development of a Charged Particle Microbeam for Targeted and Single Particle Subcellular Irradiation

Description: The development of a charged particle microbeam for single particle, subcellular irradiations at the Massachusetts Institute of Technology Laboratory for Accelerator Beam Applications (MIT LABA) was initiated under this NEER aeard. The Microbeam apparatus makes use of a pre-existing electrostatic accelerator with a horizontal beam tube.
Date: March 12, 2004
Creator: Yanch, Jacquelyn C.
Partner: UNT Libraries Government Documents Department

New Spectral Method for Halo Particle Definition in Intense Mis-matched Beams

Description: An advanced spectral analysis of a mis-matched charged particle beam propagating through a periodic focusing transport lattice is utilized in particle-in-cell (PIC) simulations. It is found that the betatron frequency distribution function of a mismatched space-charge-dominated beam has a bump-on-tail structure attributed to the beam halo particles. Based on this observation, a new spectral method for halo particle definition is proposed that provides the opportunity to carry out a quantitative analysis of halo particle production by a beam mismatch. In addition, it is shown that the spectral analysis of the mismatch relaxation process provides important insights into the emittance growth attributed to the halo formation and the core relaxation processes. Finally, the spectral method is applied to the problem of space-charge transport limits.
Date: April 27, 2011
Creator: Dorf, Mikhail A.; Davidson, Ronald C. & Startsev, Edward A.
Partner: UNT Libraries Government Documents Department

Charged-Particle-Induced Fission: A Mass Spectrometric Yield Study

Description: The products from the flssion of U induced by charged particles were studied in a mass spectrometer. Both U/sup 238/ and U/sup 235/ were bombarded with 45.7- and 24-Mev helium ions, and U/sup 238/ was also bombarded with 730-Mev protons and 100-Mev carbon ions. Tbe total chain-yields in the region of the rare-earth elemerts (mass 140 to mass 155) for most of the above bombardments and a thermal-neutron bombardment of U/sup 235/ were studied by using the isotopicdilution technique. Independent yields were measured for all the above bombardnnents for several shielded nuclides. (auth)
Date: November 1, 1959
Creator: Chu, Y. Y.
Partner: UNT Libraries Government Documents Department

An overview of Tevatron Collider Run II at Fermilab

Description: The Run II era at Fermilab began in March 2001. Many changes to the accelerator complex were made to support the Tevatron proton-antiproton collider operation with peak luminosities of 2-4 x 10{sup 32} cm{sup -2} s{sup -1} while delivering greater than 5 fb{sup -1} of integrated luminosity before the LHC begins its physics program. This report describes the current status of Run II operations and the machine performances needed to achieve the goals.
Date: December 9, 2002
Creator: Moore, Ronald S
Partner: UNT Libraries Government Documents Department

Fast ion orbits in spherical tokamaks

Description: In a spherical tokamak, the 1/R variation of the toroidal field is extreme, and for a given value of the safety factor a relatively low average toroidal field can be used, together with large plasma current and large plasma minor radius and elongation. The poloidal and toroidal fields are then of similar size. In consequence, the orbits of fast ions depart considerably from the guiding center orbits because of gyromotion in the small magnetic fields in the low field side.
Date: July 20, 1995
Creator: Solano, E.R.
Partner: UNT Libraries Government Documents Department

Relativistic charged particle in the dipole-sphere configuration I. Classical and semiclassical surface orbits

Description: The classical and semiclassical orbits of a relativistic charged particle on a rotating sphere threaded by a magnetic dipole field are examined. The rotational and dipole axes are in general not aligned. Several physically distinct regimes emerge, depending on the relative sizes of the total energy, canonical azimuthal angular momentum, and magnetic field strength. Magnetic flux enclosed by orbits is quantised very close to the poles. Application of this system to neutron star magnetic fields and questions for future research are outlined.
Date: January 1, 1997
Creator: Gopinath, K.S.; Kennedy, D.C. & Gelb, J.M.
Partner: UNT Libraries Government Documents Department

Photon-Electron Interaction and Condense Beams

Description: We discuss beams of charged particles and radiation from multiple perspectives. These include fundamental acceleration and radiation mechanisms, underlying electron-photon interaction, various classical and quantum phase-space concepts and fluctuational interpretations.
Date: November 1, 1998
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Drift Wave Test Particle Transport in Reversed Shear Profile

Description: Drift wave maps, area preserving maps that describe the motion of charged particles in drift waves, are derived. The maps allow the integration of particle orbits on the long time scale needed to describe transport. Calculations using the drift wave maps show that dramatic improvement in the particle confinement, in the presence of a given level and spectrum of E x B turbulence, can occur for q(r)-profiles with reversed shear. A similar reduction in the transport, i.e. one that is independent of the turbulence, is observed in the presence of an equilibrium radial electric field with shear. The transport reduction, caused by the combined effects of radial electric field shear and both monotonic and reversed shear magnetic q-profiles, is also investigated.
Date: June 1, 1998
Creator: Horton, W.; Park, H.B.; Kwon, J.M.; Stronzzi, D.; Morrison, P.J. & Choi, D.I.
Partner: UNT Libraries Government Documents Department

Final Report: Measurements of Core Conditions, Implosion Symmetry, and Anomaloes Acceleration Mechanisms on Omega through Charged Particle Spectroscopy, November 1, 1997 - December 31, 1998

Description: This work concerns the first spectroscopic measurements of energetic charged particles on Omega. Individual line profiles include D-3He protons (14.7 MeV) and alphas (3.6 MeV), D-T alphas (3.5 MeV), D-D protons (3.0 MeV), and D-D tutons (1.0 MeV)
Date: October 19, 1999
Creator: Petrasso, R. & Li, C.K.
Partner: UNT Libraries Government Documents Department