Fission-like products from the reaction /sup 32/S + /sup 182/W were measured over the entire angular range from theta = 10-170/sup 0/ and for bombarding energies of E/sub lab/ = 166, 177, 222, and 260 MeV using an array of eight Si detectors. From the measured energy and flight time the product mass was determined event-by-event by performing the appropriate corrections for the plasma delay and pulse height defect associated with Si detectors. The mass, angular, and total kinetic energy distributions of fission-like fragments are obtained by assuming two-body kinematics. The angular distributions indicate that a fraction of the observed cross section is associated with quasi-fission reactions as observed previously in several other reactions involving /sup 32/S projectiles. Furthermore, we observe an angular dependence of the fragment mass distributions, a feature which is strictly incompatible with compound nucleus decay. Both of these observations indicate that a fraction of fission-like products originate from quasi-fission, a process in which a large degree of mass transfer occurs between the two interaction nuclei in a short time scale. 14 refs., 4 figs., 1 tab.

The surface magneto-optic Kerr effect (SMOKE) is used to explore the magnetism of ultra-thin Fe Films extending into the monolayer regime. Both bcc ..cap alpha..-Fe and fcc ..gamma..-Fe single-crystalline, multilayer films are prepared on the bulk-terminated (1 x 1) structures of Au(100) and Cu(100), respectively. The characterizations of epitaxy and growth mode are performed using low energy electron diffraction and Auger electron spectroscopy. Monolayer-range Fe/Au(100) is ferromagnetic with a lower Curie temperature than bulk ..cap alpha..-Fe. The controversial ..gamma..-Fe/Cu(100) system exhibits a striking, metastable, surface magnetic phase at temperatures above room temperature, but does not exhibit bulk ferromagnetism.

We investigate signals for winos and zinos when the decays W ..-->.. wino + photino, Z ..-->.. wino + antiwino, and W ..-->.. wino + zino are allowed at proton-antiproton colliders. These processes lead to: (1) monojet and dijet plus missing transverse momentum (p/sub T/) events; (2) various di- and tri-lepton events with little accompanying hadronic activity; and (3) events containing jets plus leptons plus p/sub T/. Absence of such signals may allow new limits to be placed on m/sub wino/ and m/sub zino/ of at least m/sub wino/ + m/sub zino/ greater than or equal to m/sub W/, from CERN collider data. 11 refs., 4 figs.

A model including both electron-phonon coupling (as in the SSH Hamiltonian) and electron-electron interactions (on-site term U, nearest-neighbor term V) is treated within the variational scheme of Gutswiller. It is shown that for weak electron-phonon coupling the primary effect is a bond-order wave induced by electronic correlation, whereas the lattice dimerization is a secondary effect. Correspondingly the optical gap is mainly due to electronic correlation.

Orbifold compactifications provide a practical approach to string symmetry breaking. They have the potential to bridge the gap between string theory and the physics of the standard model. 7 refs., 5 figs.

The Health Physics Research Reactor (HPRR) is a small, unmoderated fast pulse reactor located at the Oak Ridge National Laboratory (ORNL). The HPRR is the principal research tool of ORNL's Dosimetry Applications Research (DOSAR) Group. The reactor is described, its operating experience is presented, and its major applications are discussed.

The rf technology program at the Oak Ridge National Laboratory (ORNL) is developing the components needed for heating in the ion cyclotron range of frequencies (ICRF) on future fusion machines, such as the Compact Ignition Tokamak. Components produced in this program are already in use on experiments throughout the world, including Doublet III-D (DIII-D), TMX-U, Alcator-C, and TEXTOR. Designs have been developed for implementation on Tore Supra and ASDEX. Recent developments in vacuum feedthroughs, compact loop antennas, high-current capacitors, and folded waveguides are discussed in this paper.

The following features, in particular, have been examined: (a) large aspect ratio (A approx. = 6), which may ease maintenance; (b) high beta (..beta.. greater than or equal to 0.20) without indentation, which brings the maximum toroidal field down to about 6 to 7 T; (c) low toroidal current (I approx. = 4MA), which reduces the cost of the current drive and equilibrium field system; and (d) steady state operation with current density control via fast and slow wave current drive. The key to high beta operation with low toroidal current lies in utilizing second stability regime equilibria with the required current distributions produced by an appropriate selection of wave driver frequencies and power spectra. The ray tracing and current drive calculation is self-consistent with the actual magnetic fields they produce in the plasma. The impurity control activities in TPSS have emphasized the self-pumping concept as applied to using the entire first wall or ''slot'' limiters. The blanket design effort has emphasized liquid metal and Flibe concepts. The reference concept is a liquid lithium/vanadium, self-cooled configuration. Overall, there exists a number of major design improvements which will substantially improve the attractiveness of tokamak reactors.

The last major conceptual design study of a tokamak power reactor in the United States was STARFIRE which was carried out in 1979-1980. Since that time US studies have concentrated on engineering test reactors, demonstration reactors, parametric systems studies, scoping studies, and studies of selected critical issues such as pulsed vs. steady-state operation and blanket requirements. During this period, there have been many advancements in tokamak physics and reactor technology, and there has also been a recognition that it is desirable to improve the tokamak concept as a commercial power reactor candidate. During 1984-1985 several organizations participated in the Tokamak Power Systems Study (TPSS) with the objective of developing ideas for improving the tokamak as a power reactor. Also, the US completed a comprehensive Blanket Comparison and Selection Study which formed the basis for further studies on improved blankets for fusion reactors.

Many spacecraft operational problems in Earth's outer magnetosphere appear to be due to intense, transient radiation phenomena. Three types of naturally-occurring, and highly variable, hostile particle radiation environments are encountered at, or near, the geostationary orbit: (1) High-energy protons due to solar flares; (2) Energetic ions and electrons produced by magnetospheric substorms; and (3) very high energy electrons of uncertain origin. Present particle sensor systems provide energetic particle detection and assessment capabilities during these kinds of high-energy radiation events. In this paper, particular emphasis is given to highly relativistic electrons (3 approx. 10 MeV). Electron fluxes and energy spectra are shown which were measured by two high-energy electron sensor systems at 6.6 R/sub E/ from 1979 through 1984. Large, persistent increases in this population were found to be relatively infrequent and sporadic in 1979-81 around solar maximum. During the approach to solar minimum (1981 to present) it is observed that the highly relativistic electrons occur with a regular 27-day periodicity, and are well associated with the re-established solar wind stream structures. Through a superposed epoch analysis technique we show that an energetic electron enhancement typically rises on a 2- to 3-day time scale and decays on 3- to 4-day time …

A simplified model of heat transfer and chemical reaction has been adapted to evaluate the expected behavior of droplets containing unreacted Zircaloy and stainless steel moving through the containment atmosphere during postulated accidents involving direct containment heating. The model includes internal and external diffusive resistances to reaction. The results indicate that reactions will be incomplete for many conditions characteristic of direct containment heating sequences.

Use of a bent single crystal to split off a small fraction of an incident high energy (400 to 800 GeV) particle beam has been demonstrated. The question which remains to be answered is: Will radiation damage effects deteriorate crystal performance in too short a time for practical application. Single Si crystals exposed to 10/sup 17/ high energy protons per cm/sup 2/ have been examined previously using low energy (1.5 to 3.0 MeV) helium ion backscattering. The amount of radiation damage indicated by this low penetration technique was very small. This paper reports verification that such an exposed crystal still channels high energy particles. Furthermore, results using helium ion backscattering following an irradiation to 10/sup 18//cm/sup 2/ predict no deterioration in channeling performance.

The sodium pumps for a liquid metal fast breeder reactor must be designed for exceptionally high reliability and long life. The principal adverse factor which tends to limit the primary pump life is cavitation which becomes potentially severe under off-design flow conditions caused by the requirement of two loop operations which resulted in a large operating flow range. This problem prompted an extensive study which included experimental investigations of scaled down and full size pumps. The investigations involved visual observations, acoustic signature recordings, and physical characteristic measurements of the model and full size impellers. The blade configuration of the model was modified several times. After each modification intensive testing was conducted with feedback to established design criteria. The results obtained from the final configuration showed excellent cavitation performance. This configuration was then machined on the full scale impeller and tested. The results confirmed acceptable performance in the entire range of operating conditions. This paper describes the test facilities erected for this study, discusses the experimental techniques employed, and presents the experimental techniques employed, and presents a sample of the experimental results.

Recent work for developing dynamical symmetries and supersymmetries is reviewed. An accurate description of odd-odd nuclei requires inclusion of the fermion-fermion force (the residual interaction) and the distinguishing of fermion configurations which are particle like and those which are hole like. A parabolic dependence of the proton-neutron multiplet in odd-odd nuclei is demonstrated. It is shown that a group structure for Bose-Fermi symmetries can be embedded in a supergroup. These methods are used to predict level schemes for Au-196 and Au-198. 11 refs., 3 figs.

The Interacting Boson Model is briefly reviewed. Recent applications of this model to the low-lying collective magnetic-dipole excitations and to the spectra of /sup 195/Ir are described. 13 refs., 3 figs.

Two-body decay of a particle is hypothesized in order to explain the lack of strong Z dependence of positron emission spectra in low-energy heavy ion collisions. The consequences of such a hypothesis are discussed, as well as recent theoretical and experimental work motivated by it. 50 refs. (LEW)

The kinetic behavior of a gamma-ray laser is comprised of an array of isomeric nuclei located at regular lattice sites in a perfect single crystal of dimensions and structure so chosen as to favor anomalous emission into that Borrmann mode having the maximum possible number of component Bragg-reflected beams, which greatly reduces the excitation requirements. The analysis of several hypothetical systems shows that superradiance, rather than amplified spontaneous emission, will then be the preferred mode of deexcitation, provided the nuclei can be pumped rapidly to a short-lived Moessbauer level while preserving crystal integrity. This warrants a search for solutions to the major problems: candidate nuclides, preparation of a storage isomer, and interlevel transfer from storage to lasing state. 10 refs., 8 figs., 2 tabs.

We study the use of such compounds in the strong, permanent magnet multipoles required for handling high energy, charged particle beams. We have made a number of SmCo/sub 5/ multipoles which have been used in a variety of ways, e.g., sextupoles for chromatic correction of the SLAC damping rings and quadrupoles for matching their associated injection and extraction lines. For applications in high radiation areas, we have used VACOMAX 170 thermally stabilized at 80/sup 0/C. Because our fabrication method uses measured characteristics of individual blocks in isolation, linearity over the operating range of the B-H curve is important. Stronger PM materials or multipole magnets increase the operating range which decreases linearity and increases unwanted harmonics. To study such effects, multipole magnets of VACODYM 370 are being made at different radii to emphasize high field effects which can drive parts of a magnet well into the third quadrant of the B-H curve. The results are compared to calculations based on various assumptions and our previous results for SmCo.

A technique is described for non-destructive measurement and monitoring of the steering offset of the electron and positron beams at the interaction point of the SLC, based on using stripline beam-position monitors to measure the centroid of one beam as it is deflected by the opposing beam. This technique is also expected to provide diagnostic information related to the spot size of the micron-size beams.

In this paper we discuss a number of space plasma phenomena which have been illuminated by a powerful diagnostic tool provided by tracing heat flux carried by the solar wind. Measurements of this flow of heat energy from the sun and other hot plasma regions have been employed to increase our understanding of the solar wind interaction with solar system objects. Similarly, anomalies in the heat flux have helped to explain unusual plasma entities which are sometimes found in the interplanetary solar wind. The heat flux is principally carried by the solar wind electrons, since they are much more mobile than the ions. The electrons conduct heat outward from the hot solar corona and in a sense they constitute test particles that trace out the various plasma structures found in the solar wind and in the vicinities of bodies immersed in the interplanetary plasma flow. In the following sections we begin by discussing the electron heat flux which flows outward from the solar corona. This flux is ordinarily found flowing in one direction, i.e., it is unidirectional. Sometimes it is observed counterstreaming, i.e., it is bidirectional. In later sections we discuss how detection of bidirectional heat fluxes has contributed to …

The infrared, optical and x-ray continua from radio quiet active galactic nuclei (AGN) are explained by a compact non-thermal source surrounding a thermal ultraviolet emitter, presumably the accretion disk around a supermassive black hole. The ultraviolet source is observed as the ''big blue bump.'' The flat (..cap alpha.. approx. = .7) hard x-ray spectrum results from the scattering of thermal ultraviolet photons by the flat, low energy end of an electron distribution ''broken'' by Compton losses; the infrared through soft x-ray continuum is the synchrotron radiation of the steep, high energy end of the electron distribution. Quantitative fits to specific AGN result in models which satisfy the variability constraints but require electron (re)acceleration throughout the source. 11 refs., 1 fig.

Brookhaven National Laboratory has completed Phase I of the Component Fragility Program and is now performing Phase II. The results of Phase I have been published in NUREG/CR-4659. In both Phases, existing test data for various models are utilized to determine the seismic fragilities of different equipment categories. This represents the first large scale attempt to assemble, compile and interpret the very large heretofore fragmented data base. In Phase I, a methodology has been established to compile the test data for variations of testing methods, vibration inputs, damping values, etc. Test response spectra have been used as a measure of the test vibration inputs. Fragility data have been collected and stored in a computerized data bank at BNL for many electrical and control equipment pieces. The data for Motor Control Centers (MCC) and Switchgears have been analyzed in Phase I for determination of the respective fragility levels. Additional test data are being collected in Phase II for these two equipment pieces, as well as other equipment categories. Statistical analyses are also being performed to estimate a single fragility descriptor for each equipment family.

Scrapers are often used in storage rings and accelerators to clean the transverse profile of the beam. When the beam is not exactly midway between the jaws of the scraper the transverse electric and magnetic fields produced by the image charges and currents are asymmetric. For a relativistic beam traveling through a longitudinally uniform tube with infinitely conducting walls the transverse force from the electric field is canceled by the transverse force from the magnetic field. When an off-center particle bunch passes by a longitudinal discontinuity in the beam tube the transverse force from the electric field are no longer cancelled by the transverse force from the magnetic field and particles in the bunch experience a transverse momentum kick which is independent of energy. It is shown that scrapers that pass close by high peak current beams can significantly degrade the beam emittance. A circular scraper was chosen for computer simulation. (LEW)

In this paper the wakefields for the Stanford Linear Accelerator Center (SLAC) accelerating structure are first discussed, and then some considerations dealing with the longitudinal wakefields are described. The main focus is on the effects of the transverse wakefield on the beam, including the case when there is an energy variation along the bunch. The use of an energy spread to inhibit emittance growth in a linac, indeed to damp the oscillations of the core of the bunch to below the unperturbed betatron oscillations, (in a process that is similar to Landau Damping) is qualitatively detailed. The example of the SLC, including errors, is also in detail.