We have carried out a number of 2D numerical simulations on an ALE code for shock-tube experiments in which a shock crosses one or more contact discontinuities and, after traveling through a homogeneous medium, reflects off a rigid wall at the end of the shock-tube and re-crosses the contact discontinuity. We have considered two-fluid and three-fluid experiments: the first fluid, which carries the original shock, is air; the other fluids are helium, freon, SF/sub 6/, or air again. Helium is lighter than air, while freon and SF/sub 6/ are heavier than air. The interface(s) between the fluids serve as contact discontinuities and are subjected to the original shock, the re-shock, and subsequent rarefactions/compressions. 9 refs., 6 figs.

Our discrete and finite version of relativistic quantum mechanics provides an elementary particle physics consistent with the standard model of quarks and leptons. Our recent relativistic calculation of the bound state spectrum of hydrogen has allowed us to make a combinatorial correction to the first order estimate of 1/..cap alpha.. = /Dirac h/c/e/sup 2/ = 137 derived from the combinatorial hierarchy and achieve agreement with experiment up to terms of order ..cap alpha../sup 3/. The same theory requires that to first order /Dirac h/c/Gm/sub p//sup 2/ = 2/sup 127/ + 136 approx. = 1.7 /times/ 10/sup 38/. Using the emission and absorption of spin 1 photons and spin 2 gravitons in this framework, we try to show that we can meet the three additional tests of general relativity---solar red shift, solar bending of light, and precession of the perihelion of Mercury. We predict that a macroscopic electromagnetic orbit would have four times the Sommerfeld precession for basically the same reason that Mercury has six times the Sommerfeld precession. 20 refs.

The gigatron is a new rf amplifier tube designed for linac collider applications. Three design features permit extension of the lasertron concept to very high frequencies. First, a gated field-emitter array is employed for the modulated cathode. Second, a ribbon beam geometry mitigates space charge depression and facilitates efficient output coupling. Third, a traveling wave output coupler is used to obtain optimum coupling to the ribbon beam. This paper describes recent developments in the gigatron design, and progress towards experimental tests. 9 refs., 8 figs., 1 tab.

We outline how ''topological confinement'' can be seen by the analysis of Regge limit infra-red divergences. We suggest that it is a necessary bridge between conventional confinement and the parton model at infinite momentum. It is produced by adding a chiral doublet of color sextet quarks to conventional QCD. An immediate signature of the resultant electroweak symmetry breaking would be large cross-sections for W/sup +/W/sup /minus// and Z/sup 0/Z/sup 0/ pairs at the CERN and Fermilab /bar p/p colliders. 24 refs.

A toroidal vortex of liquid FLiBe (LiF + BeF/sub 2/) is suggested for the blanket of a fusion reactor. Because this reactor chamber has no solid first wall, it might avoid many of the problems that accompany conventional blanket design. The liquid blanket is sustained by nozzles that inject a continuous layer of cool liquid on the inner surface. A second set of nozzles sends a stream of droplets across the diverted scrape-off layer or edge plasma to carry its heat away. The feasibility issues of most importance are judged to be avoiding turbulent breakup of the vortex and preventing too much contamination of the plasma by the evaporating FliBe. 7 refs., 5 figs., 1 tabs.

This is the second of two lectures. In the first lecture the map from a cellular automaton to a sequence of analytical approximations called the local structure theory was described. In this lecture the inverse map from approximation to the class of cellular automata approximated is constructed. The key matter is formatting the local structure theory equations in terms of block probability estimates weighted by coefficients. The inverse mapping relies on this format. Each possible assignment of values to the coefficients defines a class of automata with related statistical properties. It is suggested that these coefficients serve to smoothly parameterize the space of cellular automata. By varying the values of the parameters a cellular automaton network may be designed so that it has a specified invariant measure. If an invariant measure is considered a ''memory'' of the network, then this variation of parameters to specify the invariant measure must be considered ''learning.'' It is important to note that in this view learning is not the storage of patterns in a network, but rather the tailoring of the dynamics of a network. 7 figs.

In this lecture the map from a cellular automaton to a sequence of analytical approximations called the local structure theory is described. Connections are drawn between cellular automata and neural network models. It is suggested that the process by which a cellular automaton holds particular probability measures invariant is an appropriate model for biological memory. 20 figs.

We introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200--1000 MJ of thermonuclear yield. We present one design incorporating 2 cm of frost deposited at 0.1 g/cm/sup 3/ on an LN-cooled fiber-reinforced polymer substrate. We calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. We expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, we believe that such a frost first wall will involve little technical risk, and will be inexpensive to construct and operate. 4 refs., 1 fig.

The principal detector for AGS Experiment 810 is a Time Projection Chamber (TPC) in which it is intended to measure momenta and angles of a major fraction of the charged particles from each light ion collision. This report describes the results of a test of a prototype of the TPC in a beam of (14.6 /times/ 16 = 233.6 GeV/c) oxygen ions run in June of this year.

The status of Transverse Energy (E/sub T/) in relativistic nucleus-nucleus collisions at the Brookhaven AGS and the CERN SPS is reviewed. The definition of E/sub T/ and its physical significance are discussed. The basic techniques and limitations of the experimental measurements are presented. The acceptances of the major experiments to be discussed are shown, along with remarks about their idiosyncrasies. The data demonstrate that the nuclear geometry of colliding spheres primarily determines the shapes of the observed spectra. Careful account of the acceptances is crucial to comparing and interpreting results. It is concluded that nuclear stopping power is high, and that the amount of energy deposited into the interaction volume is increasing with beam energy even at SPS energies. The energy densities believed to be obtained at the SPS are close to the critical values predicted for the onset of a quark-gluon plasma. 25 refs., 8 figs.

Recent improvements in the Nova amplifier system allow us to deliver higher energy and power to targets and to perform experiments with higher precision. Improved operating efficiency has increased the shot rate. 4 refs., 2 figs.

Using an Elbek high-resolution magnetic spectrograph, we measured energy loss an angular distributions of MeV/nucleon projectile ions in coincidence with target recoil-ion charge state. We investigated collisions of 10 and 20 MeV C/sup 6 +/ on He, Ne, Ar, and Kr where the target atom is multiply ionized and the projectile emerges in charge state q or q-1. The amount of energy transferred to the continuum electrons exceeds, by far, the sum of the values of the ionization potentials and shows a strong target Z dependence. Both an n-body classical-trajectory Monte Carlo method (nCTMC) and an energy deposition model are used for comparison with the experimental data. 12 refs., 3 figs.

This paper discusses the following topics on synchrotrons: Dynamics of Synchrotron; Acceleration Cavity; Beam Manipulation and Beam Control; and High Intensity Effects. 21 refs., 26 figs. (LSP)

Container materials may undergo any of several modes of degradation in this environment, including: undesirable phase transformations due to lack of phase stability; atmospheric oxidation; general aqueous corrosion; pitting; crevice corrosion; intergranular stress corrosion cracking (IGSCC); and transgranular stress corrosion cracking (TGSCC). This paper is an analysis of data from the literature relevant to the pitting, crevice corrosion, and stress corrosion cracking (SCC) of these alloys. Though all three austenitic candidates have demonstrated pitting and crevice corrosion in chloride-containing environments, Alloy 825 has the greatest resistance to these forms of localized attack. Both types 304L and 316L stainless steels are susceptible to SCC in acidic chloride media. In contrast, SCC has not been documented for Alloy 825 under comparable conditions. Gamma irradiation has been found to enhance SCC of Types 304 and 304L stainless steels, but it has no detectable effect on the resistance of Alloy 825 to SCC. Furthermore, while microbiologically induced corrosion effects have been observed for 300-series stainless steels, nickel-based alloys such as Alloy 825 seem to be immune to such problems. Of the copper-based alloys, CDA 715 has the best overall resistance to localized attack. Its resistance to pitting is comparable to that of CDA 613 …

It is necessary to carefully design masks and beam lines to prevent the high energy physics detector from being inundated with background particles from a high energy linear collider. Presented here are preliminary calculations on two of the three expected backgrounds: photons from synchrotron radiation produced in the final focus quadrupoles, and electrons which lose energy due to bremsstrahlung and are then bent into a mask or quadrupole by the field of the opposite beam. The former can be controlled with proper masking. The latter may pose a problem, so further calculations are needed. Work was also done on the third expected source of background: electrons in the tail of the beam which hit masks where showers are made whose products enter the detector. This work was very preliminary and is not included in this write-up. All the calculations here are based on the 1 TeV center-of-mass linear collider design of R. Palmer and the final focus design of K. Oide which can be found in these proceedings. Extrapolations to other accelerator designs should be straightforward.

We describe the scintillation properties of Cerium Fluoride (CeF/sub 3/), a newly discovered, heavy (6.16 g/cm/sup 3/), inorganic scintillator. Its fluorescence decay lifetime, measured with the delayed coincidence method, is described by a single exponential with a 27 /+-/ ns time constant. The emission spectrum peaks at a wavelength of 340 nm, and drops to less than 10% of its peak value at 315 nm and 460 nm. When a 1 cm optical quality cube of CeF/sub 3/ is excited with 511 keV photons, a photopeak with a 20% full width at half maximum is observed at approximately half the light output of a Bismuth Germanate (BGO) crystal with similar geometry. We also present measurements of the decay time and light output of CeF/sub 3/ doped with three rare-earth elements (Dy, Er, and Pr). The short fluorescence lifetime, high density, and reasonable light output of this new scintillator suggest that it would be useful for applications where high counting rates, good stopping power, and nanosecond timing are important, such as medical imaging and nuclear science. 5 refs., 6 figs., 1 tab.

We have characterized the effects of crystal penetration by annihilation photons in circular ring positron tomographs. They are most serious in high resolution instruments having small detectors. When annihilation photons are not normally incident and penetrate some distance into the scintillator before interacting, the measurement of their transverse position becomes uncertain. This penetration of photons into the detector material before interaction is a statistical process which leads to significant displacement and anisotropy of the point spread function. The subject of this work is mathematical correction of emission datasets by performing a two-dimensional spatially variant deconvolution of the emission data in sinogram format. Examples for the Donner 600-Crystal Positron Tomograph are presented, and the amplification of statistical errors resulting from the correction procedure is also discussed. 7 refs., 9 figs., 2 tabs.

We briefly review three important methods that are currently used in the simulation of mixed systems. Two of these techniques, path integral Monte Carlo or molecular dynamics and dynamical simulated annealing, have the limitation that they can only describe the structural properties in the ground state. The third so-called quantum molecular dynamics (QMD) method can provide not only the static properties but also the real-time dynamics of a quantum particle at finite temperatures. 10 refs.

A crossbar switch backplane design (Bus Switch Backplane) based on TI's crossbar switch chip is described. This backplane holds a maximum of 16 modules and allows simultaneous communications between up to 8 pairs of modules. The aggregate data transfer rate on the backplane is 160 Mbyte/sec. The Bus Switch Backplane is an essential part of the ACP Multi Array Processor, a supercomputer for site oriented problems. The first application of this machine is in Lattice Gauge Theory calculations. The Bus Switch Backplane also finds ready application in data acquisition schemes based on the ACP multi-microprocessor system. 4 refs., 8 figs.

The formation of hot compound nuclei in intermediate-energy heavy ion reactions is discussed. The statistical decay of such compound nuclei is responsible for the abundant emission of complex fragments and high energy gamma rays. 43 refs., 23 figs.

An upper limit for the pumping speed of deuterium on 77 K surfaces has been determined by in-situ pressure measurements in a TFTR neutral beam line pumped by 423 m/sup 2/ of LN/sub 2/-cooled cryopanels. The measurement has importance for estimating the tritium retention in the beam line following operation of the ion sources with tritium. No D/sub 2/ pumping was observed. An upper limit for D/sub 2/ pumping on 77 K surfaces of less than or equal to2.4 x 10/sup -7/ l/s cm/sup 2/ was determined, corresponding to a D/sub 2/ sticking coefficient of less than or equal to1.5 x 10/sup -8/. Based on the upper limit a D-T retention factor, equal to the ratio of retained D-T to D-T input, has been determined to be less than or equal to5 x 10/sup -3/. This upper limit for D-T retention bounds the tritium inventory within the beam line to a small fraction of the tritium throughput. Comparably small upper limits for hydrogenic sticking coefficients, of the order of 10/sup -6/ - 10/sup -10/, have been determined from a review of H/sub 2/O cryotrapping measurements at 77 K and from the physical adsorption studies of H/sub 2/ on H/sub 2/O …

A field instrument is being developed for the non-invasive determination of absolute lung density using unique Compton backscattering techniques. A system consisting of a monoenergetic gamma-ray beam and a shielded high resolution high-purity-germanium (HPGe) detector in a close-coupled geometry is designed to minimize errors due to multiple scattering and uncontrollable attenuation in the chestwall. Results of studies on system performance with phantoms, the optimization of detectors, and the fabrication of a practical gamma-ray source are presented. 3 refs., 6 figs., 2 tabs.

We discuss the effects of realistic detector resolutions on the processes H ..-->.. ZZ ..-->.. e/sup +/e/sup /minus//e/sup +/e/sup /minus// and H ..-->.. ZZ ..-->.. e/sup +/e/sup minus/..mu../sup +/..mu../sup /minus// at the SSC. The background from Zt/bar t/ where the t/bar t/ system produces two isolated leptons in its decays is discussed. 10 refs., 6 figs., 2 tabs.

Many of the most impressive demonstrations of the efficient generation of vacuum ultraviolet (VUV) light have made use of two- photon resonantly enhanced four-wave mixing to generate light at ..omega../sub VUV/ = 2..omega../sub L1/ +- ..omega../sub L2/. The two-photon resonance state is coupled to the ground state both by two photons from the first laser, or by a photon from the second laser and one from the generated VUV beam. We show here that these two coherent pathways destructively interfere once the second laser is made sufficiently intense, thereby leading to an important limiting effect on the achievable conversion efficiency. 4 refs.