Particle identification in ultrarelativistic nuclear collisions (open access)

Particle identification in ultrarelativistic nuclear collisions

The role of particle identification (PID) in both fixed-target and colliding-beam studies of ultrarelativistic nuclear (URN) collisions is examined. The demands placed on the PID systems by peculiarities of URN collisions, such as large multiplicities and the need for simultaneous measurement of a number of observables, are discussed. A variety of PID techniques are reviewed, with emphasis on their applicability and efficiency in the environment of such collisions. Two examples of PID as incorporated into existing fixed-target nuclear-beam experiments are presented. 18 refs., 5 figs.
Date: April 1, 1986
Creator: DiGiacomo, N.J.
Object Type: Article
System: The UNT Digital Library
Recent developments in positron emission tomography (PET) instrumentation (open access)

Recent developments in positron emission tomography (PET) instrumentation

This paper presents recent detector developments and perspectives for positron emission tomography (PET) instrumentation used for medical research, as well as the physical processes in positron annihilation, photon scattering and detection, tomograph design considerations, and the potentials for new advances in detectors. 117 refs., 4 figs., 4 tabs.
Date: April 1, 1986
Creator: Derenzo, S.E. & Budinger, T.F.
Object Type: Article
System: The UNT Digital Library
Integral charged particle nuclear date bibliography. Editon 1, Supplement 2 (open access)

Integral charged particle nuclear date bibliography. Editon 1, Supplement 2

This bibliography is divided into three sections, ''References'', ''Target Index'', and ''Residual Index.'' The ''References'' section contains all references satisfying the following criteria: excitation functions, thick targets, or product yield leading to the formation of a ground or metastable state; the atomic mass and charge of the incident particle must be greater than or equal to 1; the atomic mass of the target must be greater than or equal to 1; and the atomic masses of the outgoing and residual nuclei must be greater than or equal to 1 with the exception of processes which do not lead to a definite residual nucleus and of gamma-ray production cross sections. The ''Target Index'' section contains the incident particle energy and the abbreviated reference lines for all the entries, which contain information on a definite target nucleus and reaction. These reference lines contain the Journal name, followed by the volume and page number. The ''Residual Index'' section also contains the incident particle energy and the abbreviated reference lines for all the entries, which contain information on a definite residual nucleus and a definite target-reaction.
Date: April 1, 1986
Creator: Holden, N. E.; Ramavataram, S. & Dunford, C. L.
Object Type: Report
System: The UNT Digital Library
Photon-Photon Physics with the Mark II at PEP (open access)

Photon-Photon Physics with the Mark II at PEP

Photon-photon interactions are studied with the Mark II detector at PEP. The inclusive production of charged hadrons at large transverse momenta and the exclusive production of meson pairs at large invarient mass are compared with recent hard scattering calculations. Copious inclusive production of K/sup 0/'s at large transverse momenta provides evidence for charm production. The radiative width of the f'(1520) is measured via its K/sub s//sup 0/ anti K/sub s//sup 0/ decay mode.
Date: April 1, 1986
Creator: Gidal, G.
Object Type: Article
System: The UNT Digital Library
Nucleon exchange in damped nuclear reactions (open access)

Nucleon exchange in damped nuclear reactions

Starting from the general context of one-body nuclear dynamics, the nucleon-exchange mechanism in damped nuclear reactions is discussed. Some of its characteristic effects on various dinuclear observables are highlighted and a few recent advances are described.
Date: April 1, 1986
Creator: Randrup, J.
Object Type: Article
System: The UNT Digital Library
Langmuir probe measurements in the TEXTOR tokamak during ALT-I pump limiter experiments (open access)

Langmuir probe measurements in the TEXTOR tokamak during ALT-I pump limiter experiments

Langmuir probes have been used to characterize the edge plasma of the TEXTOR tokamak and measure the parameters of the plasma incident on the ALT-I pump limiter during ohmic and ICRH heating. Probes mounted directly on the ALT limiter, and a scanning probe located 90/sup 0/ toroidally from the limiter, provide data for the evaluation of pump limiter performance and its effect on the edge plasma. The edge plasma is characterized by density and flux e-folding lengths of about 1.8cm when ALT is the main limiter. These scrape-off lengths do not vary significantly as ALT is moved between the normal 42-46cm minor radii, but increase to over 2.2cm when ALT is inserted to 40cm. The flux to probes at a fixed position in the limiter shadow varies by less than 25% for core density changes of a factor of five. This suggests that the global particle confinement time tau/sub p/, scales as the core density. Estimates from the probes indicate that tau/sub p/ is on the order of the energy confinement time, tau/sub E/. The edge electron temperature, T/sub e/, typically decreases by a factor of two when the core density is raised from 1 to 4 x 10/sup 13/ …
Date: April 1, 1986
Creator: Goebel, D. M.; Campbell, G. A.; Conn, R. W.; Leung, W. K.; Dippel, K. H.; Finken, K. H. et al.
Object Type: Report
System: The UNT Digital Library
1985 environmental monitoring report (open access)

1985 environmental monitoring report

The environmental monitoring program is designed to determine that BNL facilities operate such that the applicable environmental standards and effluent control requirements have been met. The data were evaluated using the appropriate environmental regulatory criteria. The environmental levels of radioactivity and other pollutants found in the vicinity of BNL during 1985 are summarized in this report. Detailed data are not included in the main body of the report, but are tabulated and presented in Appendix D. The environmental data include external radiation levels; radioactive air particulates; tritium concentrations; the amounts and concentrations of radioactivity in and the water quality of the stream into which liquid effluents are released; the water quality of the potable supply wells; the concentrations of radioactivity in biota from the stream; the concentrations of radioactivity in and the water quality of ground waters underlying the Laboratoy; concentrations of radioactivity in milk samples obtained in the vicinity of the Laboratory; and the 1984 strontium-90 data which was not available for inclusion in the 1984 Environmental Monitoring Report. In 1985, the results of the surveillance program demonstraed that the Laboratory has operated within the applicable environmental standards.
Date: April 1, 1986
Creator: Day, L.E.; Miltenberger, R.P. & Naidu, J.R. (eds.)
Object Type: Report
System: The UNT Digital Library
Rf breakdown studies in a SLAC disk-loaded structure (open access)

Rf breakdown studies in a SLAC disk-loaded structure

Rf breakdown studies in an S-band standing-wave disk-loaded accelerator structure have been completed. An equivalent traveling-wave accelerating gradient as high as 147 MV/m and a peak field in excess of 300 MV/m have been obtained. At these high gradients, considerable amounts of field emission and x-ray radiation are observed. Some of the field-emitted electrons are captured and focused by the rf fields and can be extracted on the axis of the structure. Their current, energy distribution and the x-ray radiation they produce are given. Rf processing as measured by the frequency of breakdown and the reduction in field emitted electron currents inside the structure can be speeded up considerably by the presence of argon. Some conjectures on the causes of breakdown are presented.
Date: April 1, 1986
Creator: Wang, J.W.; Nguyen-Tuong, V. & Loew, G.A.
Object Type: Article
System: The UNT Digital Library
Toward a risk assessment of the spent fuel and high-level nuclear waste disposal system. Risk assessment requirements, literature review, methods evaluation: an interim report (open access)

Toward a risk assessment of the spent fuel and high-level nuclear waste disposal system. Risk assessment requirements, literature review, methods evaluation: an interim report

This report provides background information for a risk assessment of the disposal system for spent nuclear fuel and high-level radioactive waste (HLW). It contains a literature review, a survey of the statutory requirements for risk assessment, and a preliminary evaluation of methods. The literature review outlines the state of knowledge of risk assessment and accident consequence analysis in the nuclear fuel cycle and its applicability to spent fuel and HLW disposal. The survey of statutory requirements determines the extent to which risk assessment may be needed in development of the waste-disposal system. The evaluation of methods reviews and evaluates merits and applicabilities of alternative methods for assessing risks and relates them to the problems of spent fuel and HLW disposal. 99 refs.
Date: April 1, 1986
Creator: Hamilton, L.D.; Hill, D.; Rowe, M.D. & Stern, E.
Object Type: Report
System: The UNT Digital Library
Hyperons in neutron stars (open access)

Hyperons in neutron stars

Generalized beta equilibrium involving nucleons, hyperons, and isobars is examined for neutron star matter. The hyperons produce a considerable softening of the equation of state. It is shown that the observed masses of neutron stars can be used to settle a recent controversy concerning the nuclear compressibility. Compressibilities less than 200 MeV are incompatible with observed masses. 7 refs., 9 figs.
Date: April 1, 1986
Creator: Glendenning, N.K.
Object Type: Article
System: The UNT Digital Library
Liquid-metal MHD flow in a duct whose cross section changes from a rectangle to a trapezoid, with applications in fusion blanket designs (open access)

Liquid-metal MHD flow in a duct whose cross section changes from a rectangle to a trapezoid, with applications in fusion blanket designs

This paper treats the liquid-metal MHD flow in a semi-infinite rectangular duct and a semi-infinite trapezoidal duct, which are connected by a finite-length transition duct. There is a strong, transverse, uniform magnetic field. The walls parallel to the magnetic field (sides) remain parallel, while the walls intersecting the magnetic field are twisted in the transition duct to provide the change in cross sectional shape. The left side has a constant height, while the height of the right side increases or decreases in the transition duct. This geometry gives a skewed velocity profile with a high velocity near the left side, provided the right side is relatively thick. All walls are thin and electrically conducting, but the sides are considerably thicker than the other walls. The application is to fusion-reactor blankets in which a high velocity near the first wall (separating the plasma chamber from the coolant) improves the thermal performance. Junctions of different ducts with walls parallel to the magnetic field are treated for the first time. In expansions, contractions and other geometric transition ducts, as well as in straight ducts with axially varying magnetic fields, the fluid flow and electric currents are concentrated in boundary layers adjacent to the …
Date: April 1, 1986
Creator: Walker, J.S.
Object Type: Report
System: The UNT Digital Library
Comparison of standing-wave and traveling-wave structures (open access)

Comparison of standing-wave and traveling-wave structures

The controversy over the relative advantages of standing-wave and traveling-wave linear accelerators is now in its fourth decade. It has been fed by a considerable body of misinformation. The author hopes in this paper to shed some light on the subject, and expose some of the falsehoods. The discussion is directed toward the question of which structure to use for short pulse high field electron accelerators since it is almost universally accepted that standing-wave structures are appropriate for CW and long pulse accelerators. Three arguments against standing-wave accelerators are discussed and shown to be invalid.
Date: April 1, 1986
Creator: Miller, R. H.
Object Type: Article
System: The UNT Digital Library
Migrational Characteristics, Biological Observations, and Relative Survival of Juvenile Salmonids Entering the Columbia River Estuary, 1966-1983, 1985 Final Report of Research. (open access)

Migrational Characteristics, Biological Observations, and Relative Survival of Juvenile Salmonids Entering the Columbia River Estuary, 1966-1983, 1985 Final Report of Research.

Natural runs of salmonids in the Columbia River basin have decreased as a result of hydroelectric-dam development, poor land- and forest-management, and over-fishing. This has necessitated increased salmon culture to assure adequate numbers of returning adults. Hatchery procedures and facilities are continually being modified to improve both the efficiency of production and the quality of juveniles produced. Initial efforts to evaluate changes in hatchery procedures were dependent upon adult contributions to the fishery and returns to the hatchery. Procedures were developed for sampling juvenile salmon and steelhead entering the Columbia River estuary and ocean plume. The sampling of hatchery fish at the terminus of their freshwater migration assisted in evaluating hatchery production techniques and identifying migrational or behavioral characteristics that influence survival to and through the estuary. The sampling program attempted to estimate survival of different stocks and define various aspects of migratory behavior in a large river, with flows during the spring freshet from 4 to 17 thousand cubic meters per second (m/sup 3//second).
Date: April 1, 1986
Creator: Dawley, Earl M.
Object Type: Report
System: The UNT Digital Library
Liquid-metal flow through a thin-walled elbow in a plane perpendicular to a uniform magnetic field (open access)

Liquid-metal flow through a thin-walled elbow in a plane perpendicular to a uniform magnetic field

This paper presents analytical solutions for the liquid-metal flow through two straight pipes connected by a smooth elbow with the same inside radius. The pipes and the elbow lie in a plane which is perpendicular to a uniform, applied magnetic field. The strength of the magnetic field is assumed to be sufficiently strong that inertial and viscous effects are negligible. This assumption is appropriate for the liquid-lithium flow in the blanket of a magnetic confinement fusion reactor, such as a tokamak. The pipes and the elbow have thin metal walls.
Date: April 1, 1986
Creator: Walker, J.S.
Object Type: Report
System: The UNT Digital Library
Operational experience with SLAC energy upgrade (open access)

Operational experience with SLAC energy upgrade

To produce energies of over 50 GeV for SLC, all klystron stations on the accelerator are being upgraded to produce 250 MeV energy contribution per station. This involves installing new, higher power, longer pulse klystrons, upgrading klystron modulators to provide these higher voltage, longer klystron beam pulses, and a new interlock and protection system. A new VAX based diagnostic system including automated microwave measurements, klystron beam monitors, and modulator performance checks is being implemented. Figure 1 shows a block diagram of the klystron-modulator system. To date, over half of the new klystrons have been installed and tested, the modulator upgrade program has converted 22 sectors (8 stations each) of modulators out of 30, and a four sector sampling of klystrons has been run at full SLC specs, namely 350 kV beam voltage, 3.5 microsecond pulse duration, peak output power in excess of 60 MW, and PRF of 120 pps. This paper discusses the klystron design, modulator design, interlock and diagnostic systems, and the results of the initial operation.
Date: April 1, 1986
Creator: Allen, M. A.; Cassel, R. L.; Dean, N. R.; Konrad, G. T.; Koontz, R. F.; Schwarz, H. D. et al.
Object Type: Article
System: The UNT Digital Library
Bombardment-Induced Segregation and Redistribution (open access)

Bombardment-Induced Segregation and Redistribution

During ion bombardment, a number of processes can alter the compositional distribution and microstructure in near-surface regions of alloys. The relative importance of each process depends principally on the target composition, temperature, and ion characteristics. In addition to displacement mixing leading to a randomization of atomic locations, and preferential loss of alloying elements by sputtering, which are dominant at relatively low temperatures, several thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. At elevated temperatures, nonequilibrium point defects induced by ion impacts become mobile and tend to anneal out by recombination and diffusion to extended sinks, such as dislocations, grain boundaries and free surfaces. The high defect concentrations, far exceeding the thermodynamic equilbrium values, can enhance diffusion-controlled processes, while persistent defect fluxes, originating from the spatial non-uniformity in defect production and annihilation, give rise to local redistribution of alloy constituents because of radiation-induced segregation. Moreover, when the alloy is maintained at high temperature, Gibbsian adsorption, driven by the reduction in free energy of the system, occurs even without irradiation; it involves a compositional perturbation in a few atom layers near the alloy surface. The combination of these processes leads to the complex development of a …
Date: April 1, 1986
Creator: Lam, N. Q. & Wiedersich, H.
Object Type: Article
System: The UNT Digital Library
COBRA-SFS predictions of single assembly spent fuel heat transfer data (open access)

COBRA-SFS predictions of single assembly spent fuel heat transfer data

The study reported here is one of several efforts to evaluate and qualify the COBRA-SFS computer code for use in spent fuel storage system thermal analysis. The ability of COBRA-SFS to predict the thermal response of two single assembly spent fuel heat transfer tests was investigated through comparisons of predictions with experimental test data. From these comparisons, conclusions regarding the computational treatment of the physical phenomena occurring within a storage system can be made. This objective was successfully accomplished as reasonable agreement between predictions and data were obtained for the 21 individual test cases of the two experiments.
Date: April 1, 1986
Creator: Lombardo, N. J.; Michener, T. E.; Wheeler, C. L. & Rector, D. R.
Object Type: Report
System: The UNT Digital Library
Combined Core/Boundary Layer Transport Simulations in Tokamaks (open access)

Combined Core/Boundary Layer Transport Simulations in Tokamaks

Significant new numerical results are presented from self-consistent core and boundary or scrape-off layer plasma simulations with 3-D neutral transport calculations. For a symmetric belt limiter it is shown that, for plasma conditions considered here, the pump limiter collection efficiency increases from 11% to 18% of the core efflux as a result of local reionization of blade deflected neutrals. This hitherto unobserved effect causes a significant amplification of upstream ion flux entering the pump limiter. Results from coupling of an earlier developed two-zone edge plasma model ODESSA to the PROCTR core plasma simulation code indicates that intense recycling divertor operation may not be possible because of stagnation of upstream flow velocity. This results in a self-consistent reduction of density gradient in an intermediate region between the central plasma and separatrix, and a concomitant reduction of core-efflux. There is also evidence of increased recycling at the first wall.
Date: April 1, 1986
Creator: Prinja, A. K.; Schafer, R. F., Jr.; Conn, R. W. & Howe, H. C.
Object Type: Article
System: The UNT Digital Library
Effects of a new heavy neutral vector boson at SLC and LEP (open access)

Effects of a new heavy neutral vector boson at SLC and LEP

Models with an extra neutral gauge boson (Z') are discussed. We constrain the Z' mass as a function of its mixing angle with the known Z/sup 0/ by requiring that the Z/sup 0/ mass not be shifted excessively by this mixing, and from the Higgs vacuum expectation value structure of the mass matrix. We compare these limits with those previously found from neutral current experiments. We discuss possible effects of non-excluded models on e/sup +/e/sup -/ physics at SLC and LEP. 8 refs., 3 figs.
Date: April 1, 1986
Creator: Franzini, P. J.
Object Type: Article
System: The UNT Digital Library
Proceedings of the workshop on radiation damage to wire chambers (open access)

Proceedings of the workshop on radiation damage to wire chambers

Separate abstracts were prepared for 24 papers in these workshop proceedings. (LEW)
Date: April 1, 1986
Creator: Kadyk, J.
Object Type: Article
System: The UNT Digital Library
Miniature high current metal ion source (open access)

Miniature high current metal ion source

A small, simple ion source for the production of high brightness beams of metal ions is described. A metal vapor vacuum arc discharge is used to establish the high density plasma from which the ion beam is extracted. The source is finger-sized, and can produce pulsed metal ion beams with current up to the 10 ma range. 9 refs., 6 figs.
Date: April 1, 1986
Creator: Brown, I.G.; Galvin, J.E.; MacGill, R.A. & Wright, R.T.
Object Type: Report
System: The UNT Digital Library
Transfer and breakup reactions at intermediate energies (open access)

Transfer and breakup reactions at intermediate energies

The origin of the quasi-elastic peak in peripheral heavy-ion reactions is discussed in terms of inelastic scattering and transfer reactions to unbound states of the primary projectile-like fragment. The situation is analogous to the use of reverse kinematics in fusion reactions, a technique in which the object of study is moving with nearly the beam velocity. It appears that several important features of the quasi-elastic peak may be explained by this approach. Projectile-breakup reactions have attractive features for the study of nuclear structure. They may also be used to determine the partition of excitation energy in peripheral reactions. At intermediate energies, neutron-pickup reactions leading to four-body final states become important. Examples of experiments are presented that illustrate these points. 15 refs., 14 figs.
Date: April 1, 1986
Creator: Stokstad, R.G.
Object Type: Article
System: The UNT Digital Library
Liquid-metal flow in a rectangular duct with a non-uniform magnetic field (open access)

Liquid-metal flow in a rectangular duct with a non-uniform magnetic field

This paper treats liquid-metal flow in rectangular ducts with thin conducting walls. A transverse magnetic field changes from a uniform strength upstream to a weaker uniform strength downstream. The Hartmann number and the interaction parameter are assumed to be large, while the magnetic Reynolds number is assumed to be small. If the magnetic field changes gradually over a long duct length, the velocity and pressure are nearly uniform in each cross section and the flow differs slightly from locally fully developed flow. If the magnetic field changes more abruptly over a shorter duct length, the velocity and pressure are much larger near the walls parallel to the magnetic field than in the central part of duct. Solutions for the pressure drops due to the magnetic field change are presented.
Date: April 1, 1986
Creator: Walker, J.S.
Object Type: Report
System: The UNT Digital Library
Liquid-metal flow in a thin conducting pipe near the end of a region of uniform magnetic field (open access)

Liquid-metal flow in a thin conducting pipe near the end of a region of uniform magnetic field

This paper treats the liquid-metal flow in a straight circular pipe with a thin metal wall. A strong magnetic field is applied by a magnet with parallel poles that end abruptly. In the plane midway between the magnet poles: (1) far upstream, the flow is uniform, fully developed flow in a uniform magnetic field; (2) as the flow enters the non-uniform magnetic field near the end of the magnet, the flow moves away from the central part of the pipe and becomes concentrated as two jets near the points where the magnetic field is tangent to the pipe wall; (3) further downstream where the magnetic field strength is 0(c/sup 1/6/) compared to its value upstream, the flow migrates from these jets back toward a uniform flow distributed over the entire pipe cross section. Here, c is the wall conductance ratio, which is assumed to be small. The analysis also applies to flow into the magnetic field, because inertial effects and induced magnetic fields are neglected. There are circulations of electric current in planes parallel to the magnet poles. These currents produce a pressure drop in addition to that for two fully developed flows, one in a uniform magnetic field and …
Date: April 1, 1986
Creator: Walker, J.S.
Object Type: Report
System: The UNT Digital Library