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Prospects for physics at e/sup +/e/sup -/ linear colliders (open access)

Prospects for physics at e/sup +/e/sup -/ linear colliders

The present thinking on high-energy e/sup /plus//e/sup /minus// linear colliders is reviewed, stressing those points that have consequences for detector design and physics analyses. Detector requirements are discussed. Experimental aspects of the physics that can be done at these colliders are discussed: first the general physics environment, then a standard process, W/sup /plus// W/sup /minus// detection, and finally four examples of the discovery potential of these colliders /emdash/ heavy quarks, heavy leptons, standard Higgs bosons, and charged Higgs bosons. The conclusions of this study will be stated. 23 refs., 40 figs.
Date: March 1, 1988
Creator: Feldman, G. J.
System: The UNT Digital Library
Di-leptons at the Bevalac (open access)

Di-leptons at the Bevalac

Recent results on the production of di-leptons measured by the Di-Lepton-Spectrometer (DLS) collaboration are discussed. Results are reported from observations made on p /plus/ Be collisions with proton beams from 1.0 to 4.9 GeV and on Ca collisions with calcium beams of 1.0 to 2.0 GeV/A. The shape of the distributions are similar to that at higher energies. The low mass cross section appears to be explained by ..pi..-..pi.. annihilation, but detailed calculations are needed to substantiate that hypothesis. (LEN)
Date: March 1, 1988
Creator: Matis, H.S.
System: The UNT Digital Library
Field characterization and personal dosimetry at a high energy ion accelerator (open access)

Field characterization and personal dosimetry at a high energy ion accelerator

The response of a variety of dosimeters was evaluated in the radiation field outside the shielding of the Lawrence Berkeley Laboratory Bevalac Biomedical Facility. The primary beam was 580 MeV/center dot/A neon ions, incident upon a 30.5-cm polyethylene cube. The field was characterized by a neutron spectrometer consisting of Bonner spheres and other detectors and by estimates of charged particle fluences in NTA film and in the Berklet spectrometer. The responses of American Acrylics CR-39 track-etch plastic detectors and AECL (Canada) type BD-100 Bubble Detectors were compared to those of NTA film, Andersson-Braun remmeter and recombination-chamber results as well as to reference dose equivalents based upon the unfolded neutron spectrum. Evaluations of these dosimeters are discussed. 7 refs., 4 figs.
Date: March 1, 1988
Creator: Greenhouse, N. A.; Busick, D. D.; de Castro, T. M.; Elwyn, A. J.; Hankins, D. E.; Ipe, N. E et al.
System: The UNT Digital Library
Detection of charged particles in thick hydrogenated amorphous silicon layers (open access)

Detection of charged particles in thick hydrogenated amorphous silicon layers

We show our results in detecting particles of various linear energy transfer, including minimum ionizing electrons from a Sr-90 source with 5 to 12 micron thick n-i-p and p-i-n diodes. We measured W ( average energy to produce one electron-hole pair) using 17keV filtered xray pulses with a result W = 6.0 /+-/ 0.2eV. This is consistent with the expected value for a semiconductor with band gap of 1.7 to 1.9eV. With heavily ionizing particles such as 6 MeV alphas and 1 to 2 MeV protons, there was some loss of signal due to recombination in the particle track. The minimum ionizing electrons showed no sign of recombination. Applications to pixel and strip detectors for physics experiments and medical imaging will be discussed. 7 refs., 8 figs.
Date: March 1, 1988
Creator: Fujieda, I.; Cho, G.; Kaplan, S. N.; Perez-Mendez, V.; Qureshi, S.; Ward, W. et al.
System: The UNT Digital Library
Capture reactions of /sup 40/Ca and /sup 48/Ca with targets of /sup 197/Au and /sup 208/Pb (open access)

Capture reactions of /sup 40/Ca and /sup 48/Ca with targets of /sup 197/Au and /sup 208/Pb

The reactions of /sup 40/Ca and /sup 48/Ca with targets of /sup 197/Au and /sup 208/Pb have been measured in the region from below the interaction barrier to about twice the barrier energy. The fission-like fragments were detected in a pair of position-sensitive, multi-wire proportional counters and were identified from measurements of position and time using two-body kinematics. In the region above the barrier the cross sections for capture are less than those given by the touching condition, indicating that an /open quotes/extra push/close quotes/ is required to induce capture. The observations for /sup 40/Ca and /sup 48/Ca show different fissilities for the onset of the extra push and indicate that charge equilibration may be an important factor governing capture reactions. Below the barrier the cross sections show an enhancement relative to the prediction for a one dimensional barrier. The enhancements are larger for /sup 40/Ca than for /sup 48/Ca (for both targets) and this is in qualitative agreement with predictions based on the coupling of the relative motion to low-lying collective states. Both above and below the barrier, we find that the change in the light partner, from /sup 48/Ca to /sup 40/Ca, has a larger effect on the …
Date: March 1, 1988
Creator: Stokstad, R.; Chan, Y.; Chavez, E.; Di Gregorio, D.; di Tada, M.; Gazes, S. et al.
System: The UNT Digital Library
An outdoor test facility for the large-scale production of microalgae (open access)

An outdoor test facility for the large-scale production of microalgae

The goal of the US Department of EnergySolar Energy Research Institute's Aquatic Species Program is to develop the technology base to produce liquid fuels from microalgae. This technology is being initially developed for the desert Southwest. As part of this program an outdoor test facility has been designed and constructed in Roswell, New Mexico. The site has a large existing infrastructure, a suitable climate, and abundant saline groundwater. This facility will be used to evaluate productivity of microalgae strains and conduct large-scale experiments to increase biomass productivity while decreasing production costs. Six 3-m/sup 2/ fiberglass raceways were constructed. Several microalgae strains were screened for growth, one of which had a short-term productivity rate of greater than 50 g dry wt m/sup /minus/2/ d/sup /minus/1/. Two large-scale, 0.1-ha raceways have also been built. These are being used to evaluate the performance trade-offs between low-cost earthen liners and higher cost plastic liners. A series of hydraulic measurements is also being carried out to evaluate future improved pond designs. Future plans include a 0.5-ha pond, which will be built in approximately 2 years to test a scaled-up system. This unique facility will be available to other researchers and industry for studies on microalgae …
Date: March 1, 1988
Creator: Johnson, D.A.; Weissman, J. & Goebel, R.
System: The UNT Digital Library
Electron-positron physics at 1 TeV (open access)

Electron-positron physics at 1 TeV

We discuss the motivation for TeV e/sup +/ e/sup )minus/) linear colliders, some aspects of their design, and the experimental consequences that follow from the design. After a brief discussion of the general physics environment, we consider the discovery potential of these colliders by examining three sample processes: the detection of new heavy leptons, standard Higgs bosons, and charged Higgs bosons. 13 refs., 22 figs., 5 tabs.
Date: March 1, 1988
Creator: Feldman, G. J.
System: The UNT Digital Library
Introduction to human factors (open access)

Introduction to human factors

Some background is given on the field of human factors. The nature of problems with current human/computer interfaces is discussed, some costs are identified, ideal attributes of graceful system interfaces are outlined, and some reasons are indicated why it's not easy to fix the problems. (LEW)
Date: March 1, 1988
Creator: Winters, J. M.
System: The UNT Digital Library
Breakdown phenomena in high power klystrons (open access)

Breakdown phenomena in high power klystrons

In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. …
Date: March 1, 1988
Creator: Vlieks, A. E.; Allen, M. A.; Callin, R. S.; Fowkes, W. R.; Hoyt, E. W.; Lebacqz, J. V. et al.
System: The UNT Digital Library
Simultaneously time- and space-resolved spectroscopic characterization of laser-produced plasmas (open access)

Simultaneously time- and space-resolved spectroscopic characterization of laser-produced plasmas

The CHROMA laser facility at KMS Fusion has been used to irradiate a variety of microdot targets. These include aluminum dots and mixed bromine dots doped with K-shell (magnesium) emitters. Simultaneously time- and space-resolved K-shell and L-shell spectra have been measured and compared to dynamic model predictions. The electron density profiles are measured using holographic interferometry. Temperatures, densities, and ionization distributions are determined using K-shell and L-shell spectral techniques. Time and spatial gradients are resolved simultaneously using three diagnostics: a framing crystal x-ray spectrometer, an x-ray streaked crystal spectrometer with a spatial imaging slit, and a 4-frame holographic interferometer. Significant differences have been found between the interferometric and the model-dependent spectral measurements of plasma density. Predictions by new non-stationary L-shell models currently being developed are also presented. 14 refs., 10 figs.
Date: March 3, 1988
Creator: Charatis, G.; Young, B. K. F.; Busch, G. E.; Cerjan, C. J.; Goldstein, W. H.; Osterheld, A. L. et al.
System: The UNT Digital Library
Quark Matter '87: Concluding remarks (open access)

Quark Matter '87: Concluding remarks

This year marked the beginning of the experimental program at BNL and CERN to probe the properties of ultra dense hadronic matter and to search for the quark-gluon plasma phase of matter. Possible implications of the preliminary findings are discussed. Problems needing further theoretical and experimental study are pointed out. 50 refs.
Date: March 1, 1988
Creator: Gyulassy, M.
System: The UNT Digital Library
Holdup-related issues in safeguarding of nuclear materials (open access)

Holdup-related issues in safeguarding of nuclear materials

Residual inventories of special nuclear materials (SNM) remaining in processing facilities (holdup) are recognized as an insidious problem for both safety and safeguards. This paper identifies some of the issues that are of concern to the safeguards community at-large that are related to holdup of SNM in large-scale process equipment. These issues range from basic technologies of SNM production to changing regulatory requirements to meet the needs of safeguarding nuclear materials. Although there are no magic formulas to resolve these issues, there are several initiatives that could be taken in areas of facility design, plant operation, personnel training, SNM monitoring, and regulatory guidelines to minimize the problems of holdup and thereby improve both safety and safeguards at nuclear material processing plants. 8 refs.
Date: March 1, 1988
Creator: Pillay, K.K.S.
System: The UNT Digital Library
Transportation of tritiated waste from fusion facilities (open access)

Transportation of tritiated waste from fusion facilities

This paper examines methods of handling tritiated waste from a fusion facility, concentrating on handling requirements specific to tritium. Gaseous effluent from a fusion reactor can currently be transported from a fusion facility in two forms )endash) as a gas or solidified on uranium beds. Tritiated water can be transported if it is solidified by absorption onto molecular sieve beds or on clay or cement. Solid waste being shipped for disposal can be transported in low specific activity (LSA, less than 0.3 mCig(1.1 )times) 10/sup 7/Bqg)), type A (less than or equal to 1000 CI(3.7 )times) 10/sup 13/Bq)) or type B (greater than 1000 CI(3.7 )times) 10/sup 13/Bq)) standard containers. The method chosen for transport depends on the amount and level of activity of the tritiated material and whether or not it will be reprocessed at another facility. 4 refs., 4 figs., 4 tabs.
Date: March 1, 1988
Creator: Gruetzmacher, K.M.; Carlson, R.V.; Stencel, J.R. & Sissingh, R.A.P.
System: The UNT Digital Library
Glow discharge techniques for conditioning high vacuum systems (open access)

Glow discharge techniques for conditioning high vacuum systems

A review is given of glow discharge techniques which are useful for conditioning vacuum vessels for high vacuum applications. Substantial development of glow discharge techniques has been done for the purpose of in-situ conditioning of the large ultrahigh vacuum systems for particle accelerators and magnetic fusion devices. In these applications the glow discharge treatments remove impurities from vessel surfaces in order to minimize particle-induced desorption coefficients. Cleaning mechanisms involve a mixture of sputtering and ion- (or neutral) induced desorption effects depending on the gas mixture (ArO/sub 2/ vs. H/sub 2/) and excitation method (DC, RF, and ECR). The author will review the methodology of glow discharge conditioning, diagnostic measurements provided by residual gas and surface composition analysis, and applications to vessel conditioning and materials processing. 76 refs., 16 figs.
Date: March 1, 1988
Creator: Dylla, H.F.
System: The UNT Digital Library
Recent results on open and hidden charm production in e/sup +/e/sup -/ annihilation at 29 GeV (open access)

Recent results on open and hidden charm production in e/sup +/e/sup -/ annihilation at 29 GeV

Inclusive )psi) production in e/sup +/e/sup )minus/) annihilation at 29 GeV has been measured with the Mark II detector. The )psi) cross section is found to be 1.1 )+-) 0.5 )+-) 0.4 pb. An upper limit of 0.02 sigma/sub ..mu mu../ is obtained for other sources of )psi) production. )eta) production has also been investigated, using the ..gamma gamma.. decay mode. The )eta) fragmentation function has been measured and found to be in good agreement with the Lund model prediction. )eta)' production has been measured for the first time in high energy e/sup +/e/sup )minus/) annihilation. A search for D/sub s//sup )+-/) decays into )eta) ..pi../sup )+-/) and )eta)' ..pi../sup )+-/) has been performed and evidence has been found for both decay modes at the 3 sigma level. 11 refs., 5 figs.
Date: March 1, 1988
Creator: Wormser, G.
System: The UNT Digital Library
The TITAN Reversed-Field Pinch fusion reactor study (open access)

The TITAN Reversed-Field Pinch fusion reactor study

The TITAN Reversed-Field Pinch (RFP) fusion reactor study is a multi-institutional research effort to determine the technical feasibility and key developmental issues of an RFP fusion reactor, especially at high power density, and to determine the potential economics, operations, safety, and environmental features of high-mass-power-density fusion systems. The TITAN conceptual designs are DT burning, 1000 MWe power reactors based on the RFP confinement concept. The designs are compact, have a high neutron wall loading of 18 MW/m{sup 2} and a mass power density of 700 kWe/tonne. The inherent characteristics of the RFP confinement concept make fusion reactors with such a high mass power density possible. Two different detailed designs have emerged: the TITAN-I lithium-vanadium design, incorporating the integrated-blanket-coil concept; and the TITAN-II aqueous loop-in-pool design with ferritic steel structure. This report contains a collection of 16 papers on the results of the TITAN study which were presented at the International Symposium on Fusion Nuclear Technology. This collection describes the TITAN research effort, and specifically the TITAN-I and TITAN-II designs, summarizing the major results, the key technical issues, and the central conclusions and recommendations. Overall, the basic conclusions are that high-mass power-density fusion reactors appear to be technically feasible even with …
Date: March 1, 1988
Creator: unknown
System: The UNT Digital Library
Thoughts on software and computing (open access)

Thoughts on software and computing

This talk has three distinct parts. The first two parts are on vector and parallel processing and their success, or lack thereof for HEP. The third part is an analysis on the software situation in HEP. These topics have been chosen because of the frequency with which they are discussed in the hallways of our laboratories and institutions. This review looks at the field from a particular point of view: that of an experimental physicist working with a large detector at a collider and, in addition, only considers the offline processing aspects of the field. 7 refs., 7 figs.
Date: March 1, 1988
Creator: Kunz, P. F.
System: The UNT Digital Library
Plasmon lineshape analysis in EELS of semiconductors (open access)

Plasmon lineshape analysis in EELS of semiconductors

Many materials display plasmon peaks in their low-less EELS spectra. The plasmon peak shape, energy, and linewidth are characteristic of each materials and are sensitive to the outer-shell electron density and details of the electronic band and energy-level structures. As these properties are a function not only of the composition but also the structure and chemistry of a sample, plasmon spectroscopy can potentially become a materials characterization tool which goes beyond the elemental analyses provided by EDXS and ionization-edge EELS. However, analysis of plasmon spectra requires considerably more sophistication than either of the aforementioned techniques due to the possibility of overlapping spectrum features, the prevalence of plural scattering, and the difficulty in detecting and characterizing the often subtle differences between the plasmon spectra of similar materials. As yet, no systematic approach to plasmon analysis analogous to that available commercially for EDXS or EELS core-edge analysis has been developed. We present here an approach which, for the simple case of semiconductors, makes some progress in this direction. 4 refs., 2 figs., 1 tab.
Date: March 1, 1988
Creator: Kundmann, M.K. & Gronsky, R.
System: The UNT Digital Library
Topics in nuclear chromodynamics: Color transparency and hadronization in the nucleus (open access)

Topics in nuclear chromodynamics: Color transparency and hadronization in the nucleus

The nucleus plays two complimentary roles in quantum chromodynamics: (1) A nuclear target can be used as a control medium or background field to modify or probe quark and gluon subprocesses. Some novel examples are color transparency, the predicted transparency of the nucleus to hadrons participating in high momentum transfer exclusive reactions, and formation zone phenomena, the absence of hard, collinear, target-induced radiation by a quark or gluon interacting in a high momentum transfer inclusive reaction if its energy is large compared to a scale proportional to the length of the target. (Soft radiation and elastic initial state interactions in the nucleus still occur.) Coalescence with co-moving spectators is discussed as a mechanism which can lead to increased open charm hadroproduction, but which also suppresses forward charmonium production (relative to lepton pairs) in heavy ion collisions. Also discussed are some novel features of nuclear diffractive amplitudes--high energy hadronic or electromagnetic reactions which leave the entire nucleus intact and give nonadditive contributions to the nuclear structure function at low /kappa cur//sub Bj/. (2) Conversely, the nucleus can be studied as a QCD structure. At short distances, nuclear wave functions and nuclear interactions necessarily involve hidden color, degrees of freedom orthogonal to …
Date: March 1, 1988
Creator: Brodsky, Stanley J.
System: The UNT Digital Library
Gain measurements at 5 nm in nickel-like ytterbium (open access)

Gain measurements at 5 nm in nickel-like ytterbium

Soft x-ray gain has been demonstrated at 5.03 nm within a laser produced plasma of Ni-like ytterbium. Experiments will also be described with higher Z Ni-like ions which can produce even shorter wavelength x-ray laser transition. 3 refs.
Date: March 1, 1988
Creator: MacGowan, B. J.; Bourgade, J. L.; Combis, P.; Keane, C. J.; Louis-Jacquet, M.; Matthews, D. L. et al.
System: The UNT Digital Library
Quasifragments: hot nuclei embedded in a nucleon vapor (open access)

Quasifragments: hot nuclei embedded in a nucleon vapor

In nuclear collisions at intermediate energies, metastable complex nuclear fragments are produced abundantly during the primary stage of the reaction. Therefore, statistical models for nuclear disassembly must incorporate highly excited unstable fragment states in the phase space considered. In our previous treatments of nuclear disassembly, a particular unstable fragment state was included in the final phase space provided its (estimated) half-life exceeded the time characterizing the breakup process. A similar prescription was also employed in the recent exact microcanonical model of nuclear disassembly. Although such life-time arguments are intuitively appealing in the context of a disassembling source, their relevance is less clear for the treatment of static problems, e.g. excited infinite nuclear matter at subsaturation densities. It is therefore desirable to seek a better foundation for the description of high excited nuclear states, applicable to both static and dynamical scenarios. This is also practically important for the implementation of event generators developed to provide samples of multi-fragment final states of medium-energy nuclear collisions. Furthermore, microscopic dynamical simulations also encounter the problem when seeking to give a realistic description of the final nuclear fragments.
Date: March 1, 1988
Creator: Fai, G. & Randrup, J.
System: The UNT Digital Library
Million revolution accelerator beam instrument for logging and evaluation (open access)

Million revolution accelerator beam instrument for logging and evaluation

A data acquisition and analysis instrument for the processing of accelerator beam position monitor (BPM) signals has been assembled and used preliminarily for beam diagnosis of the Fermilab accelerators. Up to eight BPM (or other analogue) channels are digitized and transmitted to an acquisition Sun workstation and from there both to a monitor workstation and a workstation for off-line (but immediate) data analysis. A coherent data description format permits fast data object transfers to and from memory, disk and tape, across the Sun ethernet. This has helped the development of both general purpose and experiment-specific data analysis, presentation and control tools. Flexible software permits immediate graphical display in both time and frequency domains. The instrument acts simultaneously as a digital oscilloscope, as a network analyzer and as a correlating, noise-reducing spectrum analyzer. 2 refs., 3 figs.
Date: March 1, 1988
Creator: Peggs, S.; Saltmarsh, C. & Talman, R.
System: The UNT Digital Library
Development of a 10-decade single-mode reactor flux monitoring system (open access)

Development of a 10-decade single-mode reactor flux monitoring system

Conventional wide-range neutron channels employ three optional modes to monitor the required flux range from source levels to full power (typically 10 or more decades). Difficult calibrations are necessary to provide a continuous output signal when such a system switches from counting mode in the source range to mean-square voltage mode in the midrange to dc current mode in the power range. In an ORNL proof-of-principle test, a method of extended range counting was implemented with a fission counter and conventional wide-band pulse processing electronics to provide a single-mode, monotonically increasing signal that spanned /approximately 10/ decades of neutron flux. Ongoing work includes design, fabrication, and testing of a comlpete neutron flux monitoring system suitable for advanced liquid metal reactor designs. 6 refs., 4 figs.
Date: March 31, 1988
Creator: Valentine, K.H.; Shepard, R.L.; Falter, K.G. & Reese, W.B.
System: The UNT Digital Library
Time-series investigation of anomalous thermocouple responses in a liquid-metal-cooled reactor (open access)

Time-series investigation of anomalous thermocouple responses in a liquid-metal-cooled reactor

A study was undertaken using SAS software to investigate the origin of anomalous temperature measurements recorded by thermocouples (TCs) in an instrumented fuel assembly in a liquid-metal-cooled nuclear reactor. SAS macros that implement univariate and bivariate spectral decomposition techniques were employed to analyze data recorded during a series of experiments conducted at full reactor power. For each experiment, data from physical sensors in the tests assembly were digitized at a sampling rate of 2/s and recorded on magnetic tapes for subsequent interactive processing with CMS SAS. Results from spectral and cross-correlation analyses led to the identification of a flow rate-dependent electromotive force (EMF) phenomenon as the origin of the anomalous TC readings. Knowledge of the physical mechanism responsible for the discrepant TC signals enabled us to device and justify a simple correction factor to be applied to future readings.
Date: March 24, 1988
Creator: Gross, K.C.; Planchon, H.P. & Poloncsik, J.
System: The UNT Digital Library