Quark deconfinement and high energy nuclear collisions (open access)

Quark deconfinement and high energy nuclear collisions

Statistical QCD predicts that with increasing density, strongly interacting matter will undergo a transition to a plasma of deconfined quarks and gluons. High energy heavy ion collisions are expected to permit experimental studies of this transition and of the predicted new state of matter. 22 refs., 6 figs.
Date: July 1, 1986
Creator: Satz, H.
System: The UNT Digital Library
Linear accelerators of the future (open access)

Linear accelerators of the future

Some of the requirements imposed on future linear accelerators to be used in electron-positron colliders are reviewed, as well as some approaches presently being examined for meeting those requirements. RF sources for use in these linacs are described, as well as wakefields, single bunches, and multiple-bunch trains. (LEW)
Date: July 1, 1986
Creator: Loew, G.A.
System: The UNT Digital Library
Highlights of the heavy ion fusion symposium (open access)

Highlights of the heavy ion fusion symposium

The current status and prospects for inertial confinement fusion based on the use of intense beams of heavy ions will be described in the light of results presented at the International Symposium on Heavy Ion Fusion, (Washington, DC, May 27-29, 1986).
Date: July 1, 1986
Creator: Keefe, D.
System: The UNT Digital Library
Fragmentation model applied to exclusive final states in photon-photon collisions (open access)

Fragmentation model applied to exclusive final states in photon-photon collisions

Monte Carlo calculations with the Lund string fragmentation model are compared to experimental results on the reactions ..gamma gamma -->..2..pi../sup +/2..pi../sup -/, ..gamma gamma -->..K/sup +/K/sup -/..pi../sup +/..pi../sup -/ and ..gamma gamma -->..p anti p..pi../sup +/..pi../sup -/. It is found, that when the parameters of the Lund model are tuned to low energy, inclusive multi hadron production in photon-photon collisions, the cross sections of exclusive processes near threshold are qualitatively reproduced. 14 refs., 3 figs.
Date: July 1, 1986
Creator: Buijs, A.
System: The UNT Digital Library
Coupled-channel analysis of neutron scattering from /sup 12/C between 9 and 15 MeV (open access)

Coupled-channel analysis of neutron scattering from /sup 12/C between 9 and 15 MeV

A deformed and energy dependent phenomenological optical model potential and coupled-channel formalism for deformed nuclei have been used in the analysis of elastic and inelastic (Q = 4.439 MeV) scattering, and analyzing power for neutrons scattered from /sup 12/C in the energy range of 9 to 15 MeV. 6 refs., 1 fig., 1 tab.
Date: July 1, 1986
Creator: Hansen, L. F. & Meigooni, A. S.
System: The UNT Digital Library
Front-end data processing the SLD data acquisition system (open access)

Front-end data processing the SLD data acquisition system

The data acquisition system for the SLD detector will make extensive use of parallel at the front-end level. Fastbus acquisition modules are being built with powerful processing capabilities for calibration, data reduction and further pre-processing of the large amount of analog data handled by each module. This paper describes the read-out electronics chain and data pre-processing system adapted for most of the detector channels, exemplified by the central drift chamber waveform digitization and processing system.
Date: July 1, 1986
Creator: Nielsen, B. S.
System: The UNT Digital Library
MEVVA ion source for high current metal ion implantation (open access)

MEVVA ion source for high current metal ion implantation

The MEVVA (Metal Vapor Vacuum Arc) ion source is a new kind of source which can produce high current beams of metal ions. Beams of a wide range of elements have been produced, spanning the periodic table from lithium up to and including uranium. The source extraction voltage is up to 60 kV, and we are increasing this up to 120 kV. A total ion beam current of over 1 Ampere has been extracted from the present embodiment of the concept, and this is not an inherent limit. The ion charge state distribution varies with cathode material and arc current, and beams like Li/sup +/, Co/sup +,2+,3+/ and U/sup 3+,4+,5+,6+/ for example, are typical; thus the implantation energy can be up to several hundred kilovolts without additional acceleration. The ion source has potential applications for ion implantation and ion beam mixing for achievement of improved corrosion resistance or wear resistance in metals or surface modification of ceramic materials and semiconductors. Here we outline the source and its performance, and describe some very preliminary implantation work using this source.
Date: July 1, 1986
Creator: Brown, I. & Washburn, J.
System: The UNT Digital Library
Control of beam dynamics in high energy induction linacs (open access)

Control of beam dynamics in high energy induction linacs

The Advent of laser-ion-guiding in the Advanced test Accelerator along with the development of accelerator cavities optimized with respect to beam breakup coupling impedence now make it possible to consider a new class of high current, high emergy linear induction accelerators. The control of the beam breakup and other instabilities by laser guiding and by various magnetic focusing schemes will be discussed along with the scaling laws for the design of such machines to minimize the growth of the beam breakup instability. Many linacs, particularly induction linacs are limited in performance by the beam breakup (BBU) instability. The instability is found in two forms. In the first form the accelerating cavities communicate with one another through interaction with the beam and through propagation of cavity fields through the accelerator structure. In the second form which is the more virulent of the two, the cavities couple to each other only through their interactions with the beam. It is this second form of PPU that will be discussed in this paper.
Date: July 29, 1986
Creator: Caporaso, G.J.
System: The UNT Digital Library
High-spin nuclear spectroscopy (open access)

High-spin nuclear spectroscopy

High-spin spectroscopy is the study of the changes in nuclear structure, properties, and behavior with increasing angular momentum. It involves the complex interplay between collective and single-particle motion, between shape and deformation changes, particle alignments, and changes in the pairing correlations. A review of progress in theory, experimentation, and instrumentation in this field is given. (DWL)
Date: July 1, 1986
Creator: Diamond, R. M.
System: The UNT Digital Library
ICF drivers: a comparison of some new entries and old standbys. Revision 1 (open access)

ICF drivers: a comparison of some new entries and old standbys. Revision 1

There has been a great deal of progress in recent years on the development of solid state and KrF lasers, light ion diodes, and heavy ion accelerators for use as drivers in inertial confinement fusion (ICF) facilities. Two relatively new entries in the ICF driver derby are the free electron laser (FEL) and the compact torus (CT). The status and remaining technological challenges of each potential driver are described. The author discusses driver performance criteria for various reactor applications and then gives his informed opinion in a qualitative rating of the six drivers for each application.
Date: July 31, 1986
Creator: Hogan, W.J.
System: The UNT Digital Library
Scaling of current density, total current, emittance, and brightness for hydrogen negative ion sources (open access)

Scaling of current density, total current, emittance, and brightness for hydrogen negative ion sources

The atomic and molecular processes that play a principal role in negative ion formation in a hydrogen negative ion discharge are discussed. The collisions of energetic electrons with gas molecules within the discharge lead to vibrationally excited molecules. Thermal electrons in turn attach to these excited molecules and generate negative ions via the dissociative attachment process. A system geometry chosen to optimize these collision processes is discussed that consists of a high-power discharge in tandem with a low electron temperature bath, the two regions separated by a magnetic filter. The current density extracted from such a system is found to scale inversely with the system scale length provided the gas density and electron density are also increased inversely with scale length. If a system is scaled downward in size to provide a new beamlet but one with increased current density, and these beamlets are packed to fill the original dimension, the new total extracted current will exceed the original total current by the scale factor. The emittance, epsilon, of the new system remains unchanged. The brightness, J/epsilon/sup 2/, of the new system will also be increased in proportion to the scale factor. 4 refs., 2 figs.
Date: July 10, 1986
Creator: Hiskes, J.R.
System: The UNT Digital Library
Anomalous dimensions of multiquark bound states (open access)

Anomalous dimensions of multiquark bound states

The evolution of six-quark color-singlet state distribution amplitudes is formulated as an application of perturbative quantum chromodynamics to nuclear wave functions. We present a general method of solving the evolution equation for multiquark bound states and predict the asymptotic Q/sup 2/ slope for the deuteron charge form factor as a result.
Date: July 1, 1986
Creator: Ji, Cheung-Ryong
System: The UNT Digital Library
Magnetic measurements of the correction and adjustment magnets of the main ring (open access)

Magnetic measurements of the correction and adjustment magnets of the main ring

Correction magnets correct the field imperfections and alignment errors of the main quadrupole and bend magnets. For reducing and controlling chromaticity there are 186 sextupoles and 78 octupoles, while for suppressing various resonances there are 12 normal and 18 skew sextupoles and 24 normal and 19 skew quadrupoles. Beam positions are individually controlled by 108 horizontal and 108 skew dipoles. This report includes results of the all Main Ring correction and adjustment magnet harmonic measurements. The measurement principle and basic equations are described.
Date: July 1, 1986
Creator: Trbojevic, D.
System: The UNT Digital Library
Two-photon exclusive processes in quantum chromodynamics (open access)

Two-photon exclusive processes in quantum chromodynamics

QCD predictions for ..gamma gamma.. annihilation into single mesons, meson pairs, and baryon pairs are reviewed. Two-photon exclusive processes provide the most sensitive and practical measure of the distribution amplitudes, and thus a critical confrontation between QCD and experiment. Both the angular distribution and virtual photon mass dependence of these amplitudes are sensitive to the shapes of the phi (chi, Q). Novel effects involving the production of qq anti q anti q states at threshold are also discussed, and a new method is presented for systematically incorporating higher-order QCD corrections in ..gamma gamma.. reactions.
Date: July 1, 1986
Creator: Brodsky, Stanley J.
System: The UNT Digital Library
Comparison of q anti qg and q anti q. gamma. events in e/sup +/e/sup -/ annihilation at PEP (open access)

Comparison of q anti qg and q anti q. gamma. events in e/sup +/e/sup -/ annihilation at PEP

In comparing the particle flow in the event plane of three-jet (q anti qg) events and of radiative annihilation events (q anti q..gamma..) for similar kinematic configurations, two PEP experiments find a significant decrease in particle density in the angular region opposite to the gluon jet in q anti qg events, relative to the particle density in the region opposite to the photon in q anti q..gamma.. events. The effect is predicted both by QCD and by phenomenological string models. 5 refs., 5 figs.
Date: July 1, 1986
Creator: Hofmann, W.
System: The UNT Digital Library
Production of muons for fusion catalysis in a magnetic mirror configuration. Revision 1 (open access)

Production of muons for fusion catalysis in a magnetic mirror configuration. Revision 1

For muon-catalyzed fusion to be of practical interest, a very efficient means of producing muons must be found. We describe a scheme for producing muons that may be more energy efficient than any heretofore proposed. There are, in particular, some potential advantages of creating muons from collisions of high energy tritons confined in a magnetic mirror configuration. If one could catalyze 200 fusions per muon and employ a uranium blanket that would multiply the neutron energy by a factor of 10, one might produce electricity with an overall plant efficiency (ratio of electric energy produced to nuclear energy released) approaching 30%. One possible near term application of a muon-producing magnetic-mirror scheme would be to build a high-flux neutron source for radiation damage studies. The careful arrangement of triton orbits will result in many of the ..pi../sup -/'s being produced near the axis of the magnetic mirror. The pions quickly decay into muons, which are transported into a small (few-cm-diameter) reactor chamber producing approximately 1-MW/m/sup 2/ neutron flux on the chamber walls, using a laboratory accelerator and magnetic mirror. The costs of construction and operation of the triton injection accelerator probably introduces most of the uncertainty in the viability of this …
Date: July 25, 1986
Creator: Moir, R.W. & Chapline, G.F. Jr.
System: The UNT Digital Library
Advanced concepts for acceleration (open access)

Advanced concepts for acceleration

Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)
Date: July 1, 1986
Creator: Keefe, D.
System: The UNT Digital Library
Conformal invariance on Calabi-Yau spaces (open access)

Conformal invariance on Calabi-Yau spaces

The possibility of superstring compactification on Calabi-Yau manifolds is analyzed. Despite the apparent non-zero ..beta.. function at four loop order, it is possible to construct a conformally invariant sigma model on a Calabi-Yau manifold. The background metric is not Ricci flat, but is related to the Ricci flat metric through a (non-local) field redefinition. 9 refs.
Date: July 1, 1986
Creator: Nemeschansky, D.
System: The UNT Digital Library
Free electron lasers for the production of infrared and millimeter waves (open access)

Free electron lasers for the production of infrared and millimeter waves

A review is presented of free electron laser (FEL) generation of electromagnetic radiation in the range from 0.5 ..mu..m to 10 mm, citing several experiments and theoretical efforts.
Date: July 1, 1986
Creator: Sessler, Andrew M.
System: The UNT Digital Library
Mathematical and numerical models to achieve high speed with special-purpose parallel processors (open access)

Mathematical and numerical models to achieve high speed with special-purpose parallel processors

One simulation facility that has been developed is the BNL Plant Analyzer, currently set up for BWR plant simulations at up to seven times faster than real-time process speeds. The principal hardware components of the BNL Plant Analyzer are two units of special-purpose parallel processors, the AD10 of Applied Dynamics International and a PDP-11/34 host computer. The AD10 is specifically designed for time-critical system simulations, utilizing the modern parallel processing technology with pipeline architecture. The simulator employs advanced modeling techniques and efficient integration techniques in conjunction with the parallel processors to achieve high speed performance.
Date: July 1, 1986
Creator: Cheng, H.S.; Wulff, W. & Mallen, A.N.
System: The UNT Digital Library
Specialty magnets (open access)

Specialty magnets

A number of basic conceptual designs are explained for magnet systems that use permanent magnet materials. Included are iron free multipoles and hybrid magnets. Also appended is a discussion of the manufacturing process and magnetic properties of some permanent magnet materials. (LEW)
Date: July 1, 1986
Creator: Halbach, K.
System: The UNT Digital Library
Statistician's view of data analysis (open access)

Statistician's view of data analysis

A brief overview of statistical data analysis is provided with a view towards examining its role in the analysis of astronomy data. 5 figs.
Date: July 1, 1986
Creator: Friedman, J.H.
System: The UNT Digital Library
Experimental review of exclusive processes in two photon reactions (open access)

Experimental review of exclusive processes in two photon reactions

Recent experimental results on exclusive final stated produced in photon-photon interactions are reviewed. Comparisons between experiments and with perturbative QCD calculations are made for meson and baryon pair production. New results on vector meson pair (rho/sup 0/rho/sup 0/,rho/sup 0/omega,rho/sup 0/phi,...) production and production of multiparticle (KK..pi pi..,K*K..pi..,...) final states are summarized. 34 refs.
Date: July 1, 1986
Creator: Ronan, M. T.
System: The UNT Digital Library
Fixed point structure of quenched, planar quantum electrodynamics (open access)

Fixed point structure of quenched, planar quantum electrodynamics

Gauge theories exhibiting a hierarchy of fermion mass scales may contain a pseudo-Nambu-Boldstone boson of spontaneously broken scale invariance. The relation between scale and chiral symmetry breaking is studied analytically in quenched, planar quantum electrodynamics in four dimensions. The model possesses a novel nonperturbative ultraviolet fixed point governing its strong coupling phase which requires the mixing of four fermion operators. 12 refs.
Date: July 1, 1986
Creator: Love, S.T.
System: The UNT Digital Library