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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


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

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

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

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

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

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


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

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

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

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

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


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

Object-Oriented Analysis Code for Hall A Vertical Drift Chambers

Description: The high-resolution spectrometers in Jefferson Lab's Hall A use vertical drift chambers to determine charged particle tracks. The current analysis code for the vertical drift chambers is difficult to maintain and modify, which has prompted the development of an object-oriented version, which will be easier to maintain and more able to adapt to changes in the detector configuration. However, the object-oriented approach involves using a slightly different algorithm than ESPACE, which could lead to different results. In this project, a preliminary version of an object-oriented analysis program for the vertical drift chambers is created and its results are compared to the existing software to determine the impacts of the differences in the reconstruction algorithms. In addition, the algorithms themselves are compared, and minor differences in track reconstruction techniques are reported.
Date: January 1, 2002
Creator: Robbins, J. & Hansen, J.O.
Partner: UNT Libraries Government Documents Department

Understanding Modern Magnets through Conformal Mapping

Description: When I had to choose, within some narrow range, the topic of this paper, I received great help from a colleague in Berkeley and from Prof. Little when it was suggested that I should pick among the possible subjects of my talk the subject that Prof. Bloch would have enjoyed most. Since Prof. Bloch would prefer a scalpel over a sword every time, I hope and think that most people will approve my choice. When one intends to talk about a subject that is as old as conformal mapping and one does not want to lose the audience in a very short time, it is advisable to start by explaining both the motivation for the talk as well as the goals one has in mind when giving the talk. This particular talk has been motivated by the increasing frequency with which one hears, from people that ought to know better, statements like: 'Conformal mapping is really a thing of the past because of all the marvelous computer programs that we now have'. Even though, or more likely because, I have been intimately involved in the development of some large and widely used computer codes, I am deeply disturbed by such statements since they indicate a severe lack of understanding of the purpose of conformal mapping techniques, computers, and computer codes. In my view, conformal mapping can be an extremely powerful computational technique, and the easy availability of computers has made that aspect even more important now than it has been in the past. Additionally, and more importantly, conformal mapping can give very deep and unique insight into problems, giving often solutions to problems that can not be obtained with any other method, in particular not with computers. Wanting to demonstrate in particular the latter part, I set myself two goals ...
Date: October 27, 1989
Creator: Halbach, K.
Partner: UNT Libraries Government Documents Department

Alignment validation

Description: The four experiments, ALICE, ATLAS, CMS and LHCb are currently under constructionat CERN. They will study the products of proton-proton collisions at the Large Hadron Collider. All experiments are equipped with sophisticated tracking systems, unprecedented in size and complexity. Full exploitation of both the inner detector andthe muon system requires an accurate alignment of all detector elements. Alignmentinformation is deduced from dedicated hardware alignment systems and the reconstruction of charged particles. However, the system is degenerate which means the data is insufficient to constrain all alignment degrees of freedom, so the techniques are prone to converging on wrong geometries. This deficiency necessitates validation and monitoring of the alignment. An exhaustive discussion of means to validate is subject to this document, including examples and plans from all four LHC experiments, as well as other high energy experiments.
Date: September 6, 2008
Creator: ALICE; ATLAS; CMS; LHCb & Golling, Tobias
Partner: UNT Libraries Government Documents Department

Recent vs from IceCube

Description: IceCube is a 1 km3 neutrino detector now being built at the South Pole. Its 4800 optical modules will detect Cherenkov radiation from charged particles produced in neutrino interactions. IceCube will search for neutrinos of astrophysical origin, with energies from 100 GeV up to 1019 eV. It will be able to separate nue, nu mu and nu tau. In addition to detecting astrophysical neutrinos, IceCube will also search for neutrinos from WIMP annihilation in the Sun and the Earth, look for low-energy (10 MeV) neutrinos from supernovae, and search for a host of exotic signatures. With the associated IceTop surface air shower array, it will study cosmic-ray air showers. IceCube construction is now 50percent complete. After presenting preliminary results from the partial detector, I will discuss IceCube's future plans.
Date: October 3, 2008
Creator: Collaboration, IceCube & Klein, Spencer R.
Partner: UNT Libraries Government Documents Department


Description: Interactions between Ar projectiles and lead are studied in terms of global observables. The Streamer Chamber at the Berkeley BEVALAC was used to record all charged particles produced in collisions between 0.8 GeV/{mu} Ar projectiles with a Pb{sub 3}O{sub 4} target. A hardware trigger selected central collisions with PB nuclei corresponding to a trigger cross section of 1 barn. In a geometrical picture this is equivalent to an impact parameter range of 0--5 fm.
Date: August 1, 1983
Creator: Renfordt, R.E.
Partner: UNT Libraries Government Documents Department

A new approach to calculate the transport matrix in RF cavities

Description: A realistic approach to calculate the transport matrix in RF cavities is developed. It is based on joint solution of equations of longitudinal and transverse motion of a charged particle in an electromagnetic field of the linac. This field is a given by distribution (measured or calculated) of the component of the longitudinal electric field on the axis of the linac. New approach is compared with other matrix methods to solve the same problem. The comparison with code ASTRA has been carried out. Complete agreement for tracking results for a TESLA-type cavity is achieved. A corresponding algorithm will be implemented into the MARS15 code. A realistic approach to calculate the transport matrix in RF cavities is developed. Complete agreement for tracking results with existed code ASTRA is achieved. New algorithm will be implemented into MARS15 code.
Date: March 1, 2011
Creator: Eidelman, Yu.; /Novosibirsk, IYF; Mokhov, N.; Nagaitsev, S.; Solyak, N. & /Fermilab
Partner: UNT Libraries Government Documents Department