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Charm photoproduction at 20 GeV including preliminary lifetime results with improved optical resolution (open access)

Charm photoproduction at 20 GeV including preliminary lifetime results with improved optical resolution

Sixty five charm events have been observed in an exposure, during 1983, of the SLAC Hybrid Facility (SHF) to a backward scattered laser beam. Preliminary results for the charmed meson lifetimes have been obtained based on 19 neutral and 22 charged decays thereby doubling our earlier data. These lifetimes are consistent with our published results and the two data samples have been combined. From the resulting 42 neutral, 45 charged and 13 topologically ambiguous decays the charmed meson lifetimes are measured to be tau/sub D/sup 0// = (6.4/sub -0.9//sup +1.1/ +- 0.5) x 10/sup -13/s and tau/sub D/sup + -// = (8.2/sub -1.1//sup +1.3/ +- 0.6) x 10/sup -13/s and their ratio tau/sub D//sup + -///tau/sub D/sup 0// = 1.3/sub -0.3/sup +0.5/. The inclusive charm cross-section at a photon energy of 20 GeV has been measured to be 60 +- 8 +- 21) nb.
Date: July 1, 1984
Creator: Colley, D. C.; Brick, D.; Bacon, T. C.; Cohn, H. O.; Franek, B.; Armenteros, R. et al.
System: The UNT Digital Library
K-edge x-ray fluorescence analysis for actinide and heavy elements solution concentration measurements (open access)

K-edge x-ray fluorescence analysis for actinide and heavy elements solution concentration measurements

Advantages of using Co-57 as an exciter for K XRFA include: a compact design that requires no x-ray tubes; the exciter-detector assembly locates remote from support electronics; on-line, at-line, or off-line configurations for monitor/measurements; systems that can be run by semi-skilled technicians, once programmed; and operated via remote terminals with results sent to control rooms; heavy element concentrations that are measurable thru industrial pipes; independent of minor changes in solution matrix or source half life with concentration results reported in near-real-time; a dynamic range of measurable concentrations that is greater than 10/sup 4/; measurement times that are reasonable even at 1 gram/liter; and for nuclear safeguards, it provides the <0.5% accuracy required by DOE for the accountability of U, Pu, or both, once the system is calibrated.
Date: July 1, 1984
Creator: Camp, David C.
System: The UNT Digital Library
Comparison of a center and off-center BWR control rod drop accident (open access)

Comparison of a center and off-center BWR control rod drop accident

A BWR control rod drop accident (RDA) induces a rapid core power transient involving strong neutronic/thermal-hydraulic coupling, which requires a detailed multi-dimensional spatial kinetics analysis. Typical two-dimensional (r,z) RDA calculations require that the dropped rod be a center rod, as a result of geometric limitations, while in three-dimensional (x,y,z) calculations the dropped rod is generally taken to be the center rod in order to allow a quarter-core representation and limit computer running times. However, for typical BWR core loadings, the highest worth rod is not necessarily the center rod and it is not known, a priori, what effect this difference in spatial location has on the RDA dynamics. In order to evaluate the effects of this simplification, three-dimensional RAMONA-3B calculations have been performed for both a center and off-center control rod drop accident.
Date: July 1, 1984
Creator: Cokinos, D.M.; Neogy, P. & Carew, J.F.
System: The UNT Digital Library
Magnetic correlations in 3d ferromagnets above T/sub c/ (open access)

Magnetic correlations in 3d ferromagnets above T/sub c/

A review is presented of our current neutron scattering experiments on Fe and Ni above the Curie temperature. Our experimental results show that the picture of propagating spin waves above T/sub c/, widely accepted since 1973, is incorrect. In addition, we will demonstrate that over wide ranges of omega, q and temperature, both, Fe and Ni, as well as Pd/sub 2/MnSn, follow a simple paramagnetic scattering function of the spin diffusion type. 14 references.
Date: July 1, 1984
Creator: Shirane, G.
System: The UNT Digital Library
Equilibration, compression and flow at the Bevalac (open access)

Equilibration, compression and flow at the Bevalac

This paper presents data acquired in the past two years by the Streamer Chamber group and the Plastic Ball group. The paper presents evidence that at Bevalac energies, head-on nuclear collisions result in stopping; it presents evidence for collective flow of the interacting nuclei; it presents evidence that a substantial part of the energy is tied up in compressional energy at the high density phase of the collision; finally, it presents recent data concerning aspects of the collisions such as interaction volume, particle ratios and temperatures. At the meeting at Bielefeld two years ago, it was not possible to make definitive statements about most of these subjects: the progress in the intervening period has been remarkable. 17 references, 14 figures, 1 table.
Date: July 1, 1984
Creator: Pugh, H.G.
System: The UNT Digital Library
Search for right-handed currents in muon decay (open access)

Search for right-handed currents in muon decay

The parameter xi, which characterizes the anisotropy of the emitted electrons relative to the spin direction of the muon, is a sensitive indicator of possible V+A admixtures to the dominant V-A weak interaction responsible for muon decay. We report here new results relating to the measurement of xi based on an experiment performed with a highly polarized surface muon beam at the TRIUMF cyclotron. The muons were stopped in thin metal foils in order to minimize depolarization effects. A spectrometer consisting of magnets and position sensitive detectors was tuned to accept electrons near the end point of the decay spectrum. Two largely independent methods were used to determine xi. In the first we measured the rate of positrons emitted in a direction opposite to the muon's spin as a function of their momentum when the stopping target was immersed in a 1.1 T longitudinal magnetic field. In the second method the stopping muons were subjected to a weak transverse magnetic field and the amplitude of their spin precession oscillation was used to determine xi. Based on the results from both methods lower limits on the mass of an intermediate vector boson which couples to right-handed weak currents are 400 GeV/c/sup …
Date: July 1, 1984
Creator: Balke, B.; Carr, J.; Gidal, G.; Gobbi, B.; Jodidio, A.; Oram, C. J. et al.
System: The UNT Digital Library
Automatic camera tracking for remote manipulators (open access)

Automatic camera tracking for remote manipulators

The problem of automatic camera tracking of mobile objects is addressed with specific reference to remote manipulators and using either fixed or mobile cameras. The technique uses a kinematic approach employing 4 x 4 coordinate transformation matrices to solve for the needed camera PAN and TILT angles. No vision feedback systems are used, as the required input data are obtained entirely from position sensors from the manipulator and the camera-positioning system. All hardware requirements are generally satisfied by currently available remote manipulator systems with a supervisory computer. The system discussed here implements linear plus on/off (bang-bang) closed-loop control with a +-2-deg deadband. The deadband area is desirable to avoid operator seasickness caused by continuous camera movement. Programming considerations for camera control, including operator interface options, are discussed. The example problem presented is based on an actual implementation using a PDP 11/34 computer, a TeleOperator Systems SM-229 manipulator, and an Oak Ridge National Laboratory (ORNL) camera-positioning system. 3 references, 6 figures, 2 tables.
Date: July 1, 1984
Creator: Stoughton, R. S.; Martin, H. L. & Bentz, R. R.
System: The UNT Digital Library
Ion beam processes in Si (open access)

Ion beam processes in Si

Observation of the effects of implants of energetic ions at high dose rates into Si have produced some exciting and interesting results. The mechanism whereby displacement damage produced by ions self-anneals during high dose rate implantation is discussed. It is shown that ion beam annealing (IBA) offers in certain situations unique possibilities for damage annealing. Annealing results of the near surface in Si with a buried oxide layer, formed by high dose implantation, are presented in order to illustrate the advantages offered by IBA. It is also shown that ion irradiation can stimulate the epitaxial recrystallization of amorphous overlayers in Si. The nonequilibrium alloying which results from such epitaxial processes is discussed as well as mechanisms which limit the solid solubility during irradiation. Finally, a dose rate dependency for the production of stable damage by ion irradiation at a constant fluence has been observed. For low fluence implants, the amount of damage is substantially greater in the case of high flux rather than low flux implantation.
Date: July 1, 1984
Creator: Holland, O.W.; Narayan, J. & Fathy, D.
System: The UNT Digital Library
Parity nonconservation in proton-proton and proton-water scattering at 1. 5 GeV/c (open access)

Parity nonconservation in proton-proton and proton-water scattering at 1. 5 GeV/c

Experiments searching for parity nonconservation in the scattering of 1.5 GeV/c (800 MeV) polarized protons from an unpolarized water target and a liquid hydrogen target are described. The intensity of the incident proton beam was measured upstream and downstream of the target by a pair of ionization detectors. The beam helicity was reversed at a 30-Hz rate. Auxiliary detectors monitored beam properties that could give rise to false effects. The result for the longitudinal asymmetry from the water is A/sub L/ = (1.7 +- 3.3 +- 1.4) x 10/sup -7/, where the first error is statistical and the second is an estimate of systematic effects. The hydrogen data yield a preliminary result of A/sub L/ = (1.0 +- 1.6) x 10/sup -7/. The systematic errors for p-p are expected to be < 1 x 10/sup -7/.
Date: July 1, 1984
Creator: Mischke, R. E.; Bowman, J. D.; Carlini, R.; MacArthur, D.; Nagle, D. E.; Frauenfelder, H. et al.
System: The UNT Digital Library
Review of trigger and on-line processors at SLAC (open access)

Review of trigger and on-line processors at SLAC

The role of trigger and on-line processors in reducing data rates to manageable proportions in e/sup +/e/sup -/ physics experiments is defined not by high physics or background rates, but by the large event sizes of the general-purpose detectors employed. The rate of e/sup +/e/sup -/ annihilation is low, and backgrounds are not high; yet the number of physics processes which can be studied is vast and varied. This paper begins by briefly describing the role of trigger processors in the e/sup +/e/sup -/ context. The usual flow of the trigger decision process is illustrated with selected examples of SLAC trigger processing. The features are mentioned of triggering at the SLC and the trigger processing plans of the two SLC detectors: The Mark II and the SLD. The most common on-line processors at SLAC, the BADC, the SLAC Scanner Processor, the SLAC FASTBUS Controller, and the VAX CAMAC Channel, are discussed. Uses of the 168/E, 3081/E, and FASTBUS VAX processors are mentioned. The manner in which these processors are interfaced and the function they serve on line is described. Finally, the accelerator control system for the SLC is outlined. This paper is a survey in nature, and hence, relies heavily …
Date: July 1, 1984
Creator: Lankford, A.J.
System: The UNT Digital Library
Refrigeration tests of the cryogenic system and solenoid for the Fermilab Collider Detector (open access)

Refrigeration tests of the cryogenic system and solenoid for the Fermilab Collider Detector

A refrigeration system for the 3 m phi x 5 m superconducting solenoid for the Collider Detector at Fermilab has been installed and operated with a dummy load. The nominal 600-W capacity of the system was achieved in the initial test. The solenoid and integral control dewar were tested in Japan with a 300-W refrigerator. The cooldown time was 7 days and the measured heat load of 35 W agrees well with the estimated value.
Date: July 1, 1984
Creator: Fast, R. W.; Aihara, K.; Dachniwskyj, R. I.; Kephart, R. D.; Kondo, K.; Minemura, H. et al.
System: The UNT Digital Library
Results on hadronic events from the MAC detector at PEP. I. Direct photon production. II. Precision R measurement and energy-energy correlations (open access)

Results on hadronic events from the MAC detector at PEP. I. Direct photon production. II. Precision R measurement and energy-energy correlations

Direct photon production in hadronic events from e/sup +/e/sup -/ ..-->.. hadrons has been studied at ..sqrt..s=29 GeV using the MAC detector at PEP. Both the charge asymmetry in the final state jets and total yield have been used to determine values of quark charges, which are in good agreement with the predictions of the fractionally charged quark-parton model. Limits have been established for anomalous sources of direct photons. Measurements of the total cross section and energy-energy correlations for e/sup +/e/sup -/ ..-->.. hadrons at ..sqrt..s=29 GeV with the MAC detector are presented. Two complementary event selections for the precision R measurement are described, one accepting events over nearly the entire 4..pi.. solid angle (minimizing extrapolation to unseen phase space), and the other restricted to wide angles (reducing two-photon backgrounds). The two methods agree, yield R = 3.93 +- 0.10 (which includes the effects of higher order radiative corrections), and given ..cap alpha../sub s/ = 0.19 +- 0.07, independent of fragmentation. The asymmetry in the energy-energy correlation cross section yields different results for ..cap alpha../sub s/ in different models, 0.185 in the string model and from 0.105 to 0.140 for incoherent jet formation, depending on the gluon fragmentation and momentum …
Date: July 1, 1984
Creator: Heltsley, B.K.
System: The UNT Digital Library
Electromagnetic shower development and applications to sampling calorimeters (open access)

Electromagnetic shower development and applications to sampling calorimeters

The application of electromagnetic theory to particle interactions is an old subject which represented one of the early successes in the study of particle interactions and fundamental forces. The ability to describe properties of electron, positron, and photon interactions has led to applications in numerous experimental devices used in high energy experiments. The subject is now considered to be relatively mature, but applications continue to evolve as new ideas are tried and new techniques become available. This report is a review of the underlying processes, a discussion of the application to electromagnetic calorimetry, discussions of some scaling laws and approximations that serve to guide designs of experimental devices, and examples where these principles are put to work. 13 references, 10 figures, 2 tables.
Date: July 1, 1984
Creator: Prescott, Charles Y.
System: The UNT Digital Library
Galaxy and cluster formation in a universe dominated by cold dark matter (open access)

Galaxy and cluster formation in a universe dominated by cold dark matter

The dark matter (DM) that appears to be gravitationally dominant on all astronomical scales larger than the cores of galaxies can be classified, on the basis of its characteristic free-streaming damping mass M/sub D/, as hot (M/sub D/ approx. 10/sup 15/ M/sub mass/), warm (M/sub D/ approx. 10/sup 11/ M/sub mass/), or cold (M/sub D < 10/sup 8/ M/sub mass/). For the case of cold DM, the shape of the DM fluctuation spectrum is determined by (a) the primordial spectrum (on scales larger than the horizon), and (b) stagspansion, the stagnation of the growth of DM fluctuations that enter the horizon while the universe is still radiation-dominated. An attractive feature of the cold dark matter hypothesis is its considerable predictive power: the post-recombination fluctuation spectrum is calculable, and it in turn governs the formation of galaxies and clusters. Good agreement with the data is obtained for a Zeldovich spectrum of primordial fluctuations.
Date: July 1, 1984
Creator: Primack, J.R.
System: The UNT Digital Library
Measuring transient radiation effects in optical fibers (open access)

Measuring transient radiation effects in optical fibers

We propose a new method for measuring transient radiation effects in optical fibers on a nanosecond timescale. The method, which incorporates a streak camera, allows more precise time resolution than other methods and has the advantage of measuring the radiation-induced attenuation as a function of wavelength and time simultaneously. By choosing different light sources and sweep speeds, radiation-induced attenuation may be measured under a variety of experimental configurations. Examples of the type of output obtained with our method are given.
Date: July 1, 1984
Creator: Rotter, M. D. & Jander, D. R.
System: The UNT Digital Library
Major results of the electron cyclotron heating experiment in the PDX tokamak (open access)

Major results of the electron cyclotron heating experiment in the PDX tokamak

Electron Cyclotron Heating (ECH) experiments on PDX have been carried out with two 60 GHz pulsed gyrotrons each yielding up to approximately 100 kW. The ECH system used two waveguide runs each about 30 meters long. One run included 5 bends and the other, 7 bends. Predetermined waveguide modes were transmitted. The electron cyclotron waves were launched in narrow beams from both the high field and the low field sides of the plasma torus. The major new physics results are: (1) efficient central electron heating for both ohmic and neutral beam heated target plasmas; (2) alteration of MHD behavior using ECH; (3) identification of the trapped electron population with ECH; and (4) signature of velocity-space time evolution during ECH. In the best heating results obtained, Thomson scattering data indicated a central temperature increase from less than or equal to 1.5 keV to greater than or equal to 2.5 keV. This occurred with an average density of about 10/sup 13/ cm/sup -3/ and approximately 80 kW outside-launch ordinary-mode heating.
Date: July 1, 1984
Creator: Hsuan, H.; Bol, K.; Bowen, N.; Boyd, D.; Cavallo, A.; Dimits, A. et al.
System: The UNT Digital Library
Fabrication and testing of a 3-m diameter superconducting solenoid for the Fermilab Collider Detector (open access)

Fabrication and testing of a 3-m diameter superconducting solenoid for the Fermilab Collider Detector

A large, 1.5-T conduction cooled superconducting solenoid for the Collider Detector at Fermilab was designed and built as part of a US-Japan international high-energy physics collaboration. Initial tests of the coil without its iron return yoke indicated that the coil performed as designed and should operate in a very stable manner when installed in the flux return iron at Fermilab.
Date: July 1, 1984
Creator: Fast, R.W.; Asano, K.; Kephart, R.D.; Kondo, K.; Kurita, I.; Minemura, H. et al.
System: The UNT Digital Library
Design and Evaluation of an Integrated Safeguards System: Principles (open access)

Design and Evaluation of an Integrated Safeguards System: Principles

An integrated safeguards system is defined as a collection of safeguards activities in which system components are coordinated to meet safeguards objectives efficiently within constraints imposed by safeguards resources, facility operations, potential adversaries, and regulatory requirements. This paper describes principles for designing and evaluating an integrated safeguards system that consists of four parts: (1) a problem definition phase that specifies resources and constraints composing the problem boundary values; (2) a system analysis/synthesis phase that describes how to select and integrate safeguards activities for efficient attainment of system objectives; (3) a system evaluation/optimization phase that defines measures of safeguards performance and develops methods for evaluating them; and (4) a decision-making phase that develops principles for selecting admissible designs and preference-ordering designs. 6 references, 4 figures, 5 tables.
Date: July 1, 1984
Creator: Markin, J. T.; Coulter, C. A.; Gutmacher, R. G. & Whitty, W. J.
System: The UNT Digital Library
Nuclear chromodynamics: applications of QCD to relativistic multiquark systems (open access)

Nuclear chromodynamics: applications of QCD to relativistic multiquark systems

We review the applications of quantum chromodynamics to nuclear multiquark systems. In particular, predictions are given for the deuteron reduced form factor in the high momentum transfer region, hidden color components in nuclear wavefunctions, and the short distance effective force between nucleons. A new antisymmetrization technique is presented which allows a basis for relativistic multiquark wavefunctions and solutions to their evolution to short distances. Areas in which conventional nuclear theory conflicts with QCD are also briefly reviewed. 48 references.
Date: July 1, 1984
Creator: Brodsky, S.J. & Ji, C.R.
System: The UNT Digital Library
Evidence for a narrow massive state in the radiative decays of the Upsilon (open access)

Evidence for a narrow massive state in the radiative decays of the Upsilon

Evidence is presented for a state, which we call zeta, with a mass M = (8322 +- 8 +- 24) MeV and a line width GAMMA < 80 MeV (90% confidence level) obtained using the Crystal Ball (NaI(Tl) detector at DORIS II. Radiative transitions to this state are observed from about 100,000 UPSILON(1S) decays in two independent sets of data: one in which zeta ..-->.. multiple hadrons, and one which is strongly biased towards zeta ..-->.. 2 low multiplicity jets. The branching ratio to this state from the UPSILON(1S) is of order 0.5%.
Date: July 1, 1984
Creator: Collaboration, Crystal Ball
System: The UNT Digital Library
Heat transfer through He II in a 9. 6 m long 35 mm ID tube (open access)

Heat transfer through He II in a 9. 6 m long 35 mm ID tube

The limiting heat flux at the onset of He I was measured in a 9.6 m long tube of 35 mm ID at a bath temperature between 1.8 K and T/sub lambda/ and a pressure of 1 atm. The measured limiting heat flux during axial heating is 50% more than end heating at the same bath temperature. Both cases agrees with the Gorter-Mellink mutual friction theory.
Date: July 1, 1984
Creator: Caspi, S. & Schafer, R.V.
System: The UNT Digital Library
H-modes studies in PDX (open access)

H-modes studies in PDX

A regime of enhanced energy confinement during neutral beam heating has been obtained routinely in the PDX tokamak after modifications to form a closed divertor geometry. Plasma density profiles were broad and the electron temperature at the plasma edge reached values of approx. 400 eV in the H-mode phase of a discharge. A comparison of closed divertor discharges with moderate and intense gas puffing indicates that a requirement for obtaining high confinement times is the localization of the plasma fueling source in the divertor throat region. While high confinement was attained at moderate injected powers (P/sub INJ/ less than or equal to 3 MW), confinement was degraded at higher powers due to both increased edge instabilities and, especially, the intense gas puffing needed to prevent disruptions. Initial results with a particle scoop limiter indicate high particle confinement times and energy confinement times approaching those of diverted H-mode plasmas.
Date: July 1, 1984
Creator: Fonck, R.J.; Beirsdorfer, P.; Bell, M.; Bol, K.; Boyd, D.; Buchenauer, D. et al.
System: The UNT Digital Library
Time-Resolved Tomographic Images of a Relativistic Electron Beam (open access)

Time-Resolved Tomographic Images of a Relativistic Electron Beam

We obtained a sequential series of time-resolved tomographic two-dimensional images of a 4.5-MeV, 6-kA, 30-ns electron beam. Three linear fiber-optic arrays of 30 or 60 fibers each were positioned around the beam axis at 0/sup 0/, 61/sup 0/, and 117/sup 0/. The beam interacting with nitrogen at 20 Torr emitted light that was focused onto the fiber arrays and transmitted to a streak camera where the data were recorded on film. The film was digitized, and two-dimensional images were reconstructed using the maximum-entropy tomographic technique. These images were then combined to produce an ultra-high-speed movie of the electron-beam pulse.
Date: July 1, 1984
Creator: Koehler, H. A.; Jacoby, B. A. & Nelson, M.
System: The UNT Digital Library
EXAFS and Moessbauer study of small metal clusters isolated in rare-gas solids (open access)

EXAFS and Moessbauer study of small metal clusters isolated in rare-gas solids

The determination of the interatomic separation in small metal clusters is of great importance. For instance, the knowledge of this parameter permits one to carry out theoretical calculations on small clusters to predict their experimentally measured properties. There have been several electron diffraction studies to determine the lattice parameter for various cluster sizes. However, a simple interpretation of the electron diffraction data for small clusters is often unreliable and this obscures the determination of the atomic separation. On the other hand, EXAFS provides a unique approach to such measurements on small clusters. We have undertaken a general program of isolating small metal clusters in rare-gas solids and measuring the atomic separation in them using EXAFS. It should be emphasized that the small cluster will not interact with the rare-gas supports and hence will not disturb the electronic and geometric properties of atoms in such isolated clusters. In this summary report, such data is presented for clusters of Cr and Fe isolated in neon and those for Ag clusters in argon. In the case of Fe clusters isolated in argon and xenon, we have also carried out the measurements of the isomer shift and the magnetic hyperfine field at Fe-57 nucleus …
Date: July 1, 1984
Creator: Montano, P. A.; Shenoy, G. K.; Morrison, T. I. & Schulze, W.
System: The UNT Digital Library