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Studies in medium energy physics (open access)

Studies in medium energy physics

This report discusses the following research: p + A precision elastic forward angle cross sections; polarized nuclear target project; and search for very rare K{sup L} decays. (LSP)
Date: December 1, 1991
Creator: Green, A.; Hoffmann, G. W.; McDonough, J.; Purcell, M. J.; Ray, R. L.; Read, D. E. et al.
Object Type: Report
System: The UNT Digital Library
Studies in medium energy physics (open access)

Studies in medium energy physics

This document constitutes the (1991--1992) technical progress report and continuation proposal for the ongoing medium energy nuclear physics research program supported by the US Department of Energy through special Research Grant DE-FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF) and the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics; (2) provide unique, first-of-a-kind exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics.
Date: December 1, 1991
Creator: Green, A.; Hoffmann, G. W.; McDonough, J.; Purcell, M. J.; Ray, R. L.; Read, D. E. et al.
Object Type: Report
System: The UNT Digital Library
Studies in medium energy physics. Progress report and continuation proposal, April 1, 1991--March 31, 1992: Addendum (open access)

Studies in medium energy physics. Progress report and continuation proposal, April 1, 1991--March 31, 1992: Addendum

This document constitutes the (1991--1992) technical progress report and continuation proposal for the ongoing medium energy nuclear physics research program supported by the US Department of Energy through special Research Grant DE-FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory`s (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF) and the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics; (2) provide unique, first-of-a-kind ``exploratory`` hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics.
Date: December 1, 1991
Creator: Green, A.; Hoffmann, G. W.; McDonough, J.; Purcell, M. J.; Ray, R. L.; Read, D. E. et al.
Object Type: Report
System: The UNT Digital Library
Studies in medium energy physics. Progress report, April 1, 1991--March 31, 1992 (open access)

Studies in medium energy physics. Progress report, April 1, 1991--March 31, 1992

This report discusses the following research: p + A precision elastic forward angle cross sections; polarized nuclear target project; and search for very rare K{sup L} decays. (LSP)
Date: December 1, 1991
Creator: Green, A.; Hoffmann, G. W.; McDonough, J.; Purcell, M. J.; Ray, R. L.; Read, D. E. et al.
Object Type: Report
System: The UNT Digital Library
A two-dimensional ACAR study of untwinned YBa sub 2 Cu sub 3 O sub 7-x (open access)

A two-dimensional ACAR study of untwinned YBa sub 2 Cu sub 3 O sub 7-x

We have carried out 2D-ACAR measurements on an untwinned single crystal of YBa{sub 2}Cu{sub 3}O{sub 7-x} as a function of temperature, for five temperatures ranging from 30K to 300K. We show that these temperature dependent 2D-ACAR spectra can be described to a good approximation as a superposition of two temperature independent spectra with temperature dependent weighting factors. We show further how the data can be used to correct for the background'' in the experimental spectrum. Such a background corrected'' spectrum is in remarkable accord with the corresponding band theory predictions, and displays in particular clear signatures of the electron ridge Fermi surface.
Date: December 1, 1991
Creator: Smedskjaer, L.C. (Argonne National Lab., IL (United States)) & Bansil, A. (Northwestern Univ., Evanston, IL (United States). Dept. of Physics)
Object Type: Article
System: The UNT Digital Library
A two-dimensional ACAR study of untwinned YBa{sub 2}Cu{sub 3}O{sub 7-x} (open access)

A two-dimensional ACAR study of untwinned YBa{sub 2}Cu{sub 3}O{sub 7-x}

We have carried out 2D-ACAR measurements on an untwinned single crystal of YBa{sub 2}Cu{sub 3}O{sub 7-x} as a function of temperature, for five temperatures ranging from 30K to 300K. We show that these temperature dependent 2D-ACAR spectra can be described to a good approximation as a superposition of two temperature independent spectra with temperature dependent weighting factors. We show further how the data can be used to correct for the ``background`` in the experimental spectrum. Such a ``background corrected`` spectrum is in remarkable accord with the corresponding band theory predictions, and displays in particular clear signatures of the electron ridge Fermi surface.
Date: December 1, 1991
Creator: Smedskjaer, L. C. & Bansil, A.
Object Type: Article
System: The UNT Digital Library
The Ranger (San Antonio, Tex.), Vol. 66, No. 13, Ed. 1 Friday, January 25, 1991 (open access)

The Ranger (San Antonio, Tex.), Vol. 66, No. 13, Ed. 1 Friday, January 25, 1991

Weekly student newspaper from San Antonio College in San Antonio, Texas that includes campus news along with advertising.
Date: January 25, 1991
Creator: San Antonio College
Object Type: Newspaper
System: The Portal to Texas History
Ligand Substitution Studies in the Tetracobalt Cluster Co₄(CO)₁₀([mu]₄-PPh₂) and Synthesis and Reactivity Studies in the Fe₂Pt and FeCo₂ Mixed-metal Clusters (open access)

Ligand Substitution Studies in the Tetracobalt Cluster Co₄(CO)₁₀([mu]₄-PPh₂) and Synthesis and Reactivity Studies in the Fe₂Pt and FeCo₂ Mixed-metal Clusters

The kinetics of ligand substitution for CO in Co4(CO)10(mu4-PPh2) , 1, have been investigated for the ligands P(OMe)3, P(OEt)3, PPh2H, P(0-i-Pr)3, P(n-Bu)3, PPh3, P(i-Pr)3, and PCy3 over a wide temperature range.
Date: August 1991
Creator: Don, Ming-jaw
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The Ranger (San Antonio, Tex.), Vol. 67, No. 8, Ed. 1 Friday, November 1, 1991 (open access)

The Ranger (San Antonio, Tex.), Vol. 67, No. 8, Ed. 1 Friday, November 1, 1991

Weekly student newspaper from San Antonio College in San Antonio, Texas that includes campus news along with advertising.
Date: November 1, 1991
Creator: San Antonio College
Object Type: Newspaper
System: The Portal to Texas History
Castroville News Bulletin (Castroville, Tex.), Vol. 32, No. 44, Ed. 1 Thursday, October 31, 1991 (open access)

Castroville News Bulletin (Castroville, Tex.), Vol. 32, No. 44, Ed. 1 Thursday, October 31, 1991

Weekly newspaper from Castroville, Texas that includes local, state, and national news along with extensive advertising.
Date: October 31, 1991
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
Relativistic atomic beam spectroscopy II (open access)

Relativistic atomic beam spectroscopy II

We are requesting support for a postdoctoral person to participate in H{sup -} studies at Los Alamos. In addition, we are requesting funding for a state-of-the-art YAG laser system that would allow us to obtain data at three times our present rate with improved beam quality.
Date: December 31, 1991
Creator: unknown
Object Type: Report
System: The UNT Digital Library
The Ranger (San Antonio, Tex.), Vol. 66, No. 21, Ed. 1 Thursday, March 28, 1991 (open access)

The Ranger (San Antonio, Tex.), Vol. 66, No. 21, Ed. 1 Thursday, March 28, 1991

Weekly student newspaper from San Antonio College in San Antonio, Texas that includes campus news along with advertising.
Date: March 28, 1991
Creator: San Antonio College
Object Type: Newspaper
System: The Portal to Texas History
Nuclear structure studies at intermediate energies. Progress report, July 1990--July 1991 (open access)

Nuclear structure studies at intermediate energies. Progress report, July 1990--July 1991

This report discusses the following topics: development of (p, 2p) coincidence studies at MRS; analysis of {sup 206, 207, 208}Pb(p, p{prime}) data from E855; and computer program development.
Date: July 1, 1991
Creator: Hintz, N. M.
Object Type: Report
System: The UNT Digital Library
Nuclear structure studies at intermediate energies (open access)

Nuclear structure studies at intermediate energies

This report discusses the following topics: development of (p, 2p) coincidence studies at MRS; analysis of {sup 206, 207, 208}Pb(p, p{prime}) data from E855; and computer program development.
Date: July 1, 1991
Creator: Hintz, Norton M.
Object Type: Report
System: The UNT Digital Library
Pulsed laser kinetic studies of liquids under high pressure (open access)

Pulsed laser kinetic studies of liquids under high pressure

A high pressure apparatus constructed for measuring the rates of reactions in liquids under pressures ranging from 1 atm to 2000 atm has been used to measure the complexation kinetics of molybdenum hexacarbonyl reacting with 2,2-bipyridine, 4,4{prime}-dimethyl-2-2{prime}-bipyridine and 4,4{prime}-diphenyl-2-2{prime} bipyridine in toluene. Pentacarbonyl reaction intermediates are created by a 10 nsec flash of frequency tripled Nd:YAG laser light. Measured activation volumes for chelate ligand ring closure indicate a change in mechanism from associative interchange to dissociative interchange as steric hindrance increases. A similar high pressure kinetics study of molybdenum carbonyl complexation by several substituted phenanthrolines is now well advanced that indicates that with the more rigid phenanthroline ligands steric effects from bulky substituents have less effect on the ring closure mechanism than in the case of the bipyridine ligands. An experimental concentration dependence of the fluorescence quantum yield of cresyl violet has been harmonized with previously published contradictory reports. Fluorescence of cresyl violet in various solvents and in micellar systems has also been systematically explored.
Date: November 25, 1991
Creator: Eyring, E.M.
Object Type: Report
System: The UNT Digital Library
Pulsed Laser Kinetic Studies of Liquids Under High Pressure. Progress Report, November 29, 1990--November 25, 1991 (open access)

Pulsed Laser Kinetic Studies of Liquids Under High Pressure. Progress Report, November 29, 1990--November 25, 1991

A high pressure apparatus constructed for measuring the rates of reactions in liquids under pressures ranging from 1 atm to 2000 atm has been used to measure the complexation kinetics of molybdenum hexacarbonyl reacting with 2,2-bipyridine, 4,4{prime}-dimethyl-2-2{prime}-bipyridine and 4,4{prime}-diphenyl-2-2{prime} bipyridine in toluene. Pentacarbonyl reaction intermediates are created by a 10 nsec flash of frequency tripled Nd:YAG laser light. Measured activation volumes for chelate ligand ring closure indicate a change in mechanism from associative interchange to dissociative interchange as steric hindrance increases. A similar high pressure kinetics study of molybdenum carbonyl complexation by several substituted phenanthrolines is now well advanced that indicates that with the more rigid phenanthroline ligands steric effects from bulky substituents have less effect on the ring closure mechanism than in the case of the bipyridine ligands. An experimental concentration dependence of the fluorescence quantum yield of cresyl violet has been harmonized with previously published contradictory reports. Fluorescence of cresyl violet in various solvents and in micellar systems has also been systematically explored.
Date: November 25, 1991
Creator: Eyring, Edward M.
Object Type: Report
System: The UNT Digital Library
Infrared Synchrotron Radiation instrumentation and applications (open access)

Infrared Synchrotron Radiation instrumentation and applications

Infrared Synchrotron Radiation (IRSR) is a blossoming field which has three working beamlines, U4IR at the National Synchrotron Light Source, Brookhaven National Laboratory, USA, and two at the Institute of Molecular Sciences in Okasaki, Japan with extensive research projects. There are also several new beamlines in the planning and development stages, both in the United States and abroad. IRSR offers a unique way to access the far infrared (30 {mu} to approx 1 mm) which is a notoriously difficult region to work in. In particular, experiments that demand high brightness are well suited to IRSR just as they are in the x-ray region. The central issue in all of the experiments to data has been good signal to noise, which has been the focus of the instrumentation improvements at the U4IR beamline. A commercial Fourier transform instrument was the chosen spectrometer. Then modifications were made in order to expand the usable region of the existing experiments, in both the far and near infrared. As an example of the performance of this beamline, I will focus on the reflection absorption spectroscopy results for adsorbates on clean surfaces in ultra-high vacuum. 15 refs.
Date: January 1, 1991
Creator: Hirschmugl, C. (Yale Univ., New Haven, CT (United States). Dept. of Applied Physics)
Object Type: Article
System: The UNT Digital Library
Binding and catalytic reduction of NO by transition metal aluminosilicates (open access)

Binding and catalytic reduction of NO by transition metal aluminosilicates

The objective of this research is to provide the scientific understanding of processes that actively and selectively reduce NO in dilute exhaust streams, as well as in concentrated streams, to N{sub 2}. Experimental studies of NO chemistry in transition metal-containing aluminosilicate catalysts are being carried out with the aim of determining the chemical rules for NO reduction on non-precious metals. The catalyst supports chosen for this investigation are A and Y zeolites, mordenite, and monoliths based on cordierite. The supported transition metal cations that were examined are principally the first row redox metals, e.g. Cr(2), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Cu(I). The reactions of interest are the reductions of NO by H{sub 2}, CO, and CH{sub 4}, as well as the disproportionation of NO. Rare earth cations that possess redox properties were placed in the more shielded sites, e.g. Site I in Y zeolite, prior to or simultaneously with the exchange procedure with the transition metal cations. Theoretical calculations of the electronic structure of the transition metal cations in zeolitic sites were carried out by ab initio methods. The aim of this part of the research is to find the best match between the metal-based antibonding orbitals and the …
Date: September 1, 1991
Creator: Klier, Kamil; Herman, Richard G. & Hou, Shaolie
Object Type: Report
System: The UNT Digital Library
Infrared synchrotron radiation instrumentation and applications (open access)

Infrared synchrotron radiation instrumentation and applications

Infrared synchrotron radiation (IRSR) in the wavelength range from 1{mu}m to {approximately}1cm has now been used quite extensively both in Japan at UVSOR, Okasaki and in the United States at the NSLS, Brookhaven. The use of IRSR poses many new challenges, none the least of which is the fact that the radiation covers four decades of energy and is also very divergent and subject to diffraction. However the advantages are particularly significant due to the 1000 fold increase in brightness available over conventional sources in a region where detectors become a limiting factor. In addition, IRSR is also highly spatially coherent allowing the possibility of a new class of interferometers based on wavefront division. We will discuss this and other instrument issues as they critically relate to experiments. The applications discussed will be in the areas of surface vibrational spectroscopy, both in ultra-high vacuum and in electro-chemical cells, and in areas which use the pulsed nature of the source both for fast response studies and for pump-probe studies. 8 refs., 8 figs.
Date: January 1, 1991
Creator: Williams, G. P.
Object Type: Article
System: The UNT Digital Library
Infrared Synchrotron Radiation instrumentation and applications (open access)

Infrared Synchrotron Radiation instrumentation and applications

Infrared Synchrotron Radiation (IRSR) is a blossoming field which has three working beamlines, U4IR at the National Synchrotron Light Source, Brookhaven National Laboratory, USA, and two at the Institute of Molecular Sciences in Okasaki, Japan with extensive research projects. There are also several new beamlines in the planning and development stages, both in the United States and abroad. IRSR offers a unique way to access the far infrared (30 {mu} to approx 1 mm) which is a notoriously difficult region to work in. In particular, experiments that demand high brightness are well suited to IRSR just as they are in the x-ray region. The central issue in all of the experiments to data has been good signal to noise, which has been the focus of the instrumentation improvements at the U4IR beamline. A commercial Fourier transform instrument was the chosen spectrometer. Then modifications were made in order to expand the usable region of the existing experiments, in both the far and near infrared. As an example of the performance of this beamline, I will focus on the reflection absorption spectroscopy results for adsorbates on clean surfaces in ultra-high vacuum. 15 refs.
Date: December 31, 1991
Creator: Hirschmugl, C.
Object Type: Article
System: The UNT Digital Library
Raman and NMR Investigation of Molecular Reorientation and Internal Rotation in Liquids (open access)

Raman and NMR Investigation of Molecular Reorientation and Internal Rotation in Liquids

Molecular rotational motions are known to influence both Raman scattering of light and nuclear spin relaxation. Therefore, the application of Raman bandshape analysis and NMR relaxation time measurements to probe molecular dynamics in liquids will provide us with a deeper understanding of the dynamical behavior and structure of molecules in the liquid phase. Presented here are (i) studies of molecular reorientation of acetonitrile in the neat liquid phase and in solution by Raman bandshape analysis and NMR relaxation; (ii) studies of reorientational dynamics and internal rotation in transition metal clusters by NMR relaxation.
Date: December 1991
Creator: Yuan, Peng
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Principal Resonance Contributors to High-Valent, Transition-Metal Alkylidene Complexes (open access)

Principal Resonance Contributors to High-Valent, Transition-Metal Alkylidene Complexes

Article discussing principal resonance contributors to high-valent, transition-metal alkylidene complexes.
Date: July 1991
Creator: Cundari, Thomas R., 1964- & Gordon, Mark S.
Object Type: Article
System: The UNT Digital Library
Positron 2D-ACAR experiments and electron-positron momentum density in YBa sub 2 Cu sub 3 O sub 7-x (open access)

Positron 2D-ACAR experiments and electron-positron momentum density in YBa sub 2 Cu sub 3 O sub 7-x

We discuss positron annihilation (2D-ACAR) measurements in the C- projection on an untwinned metallic single crystal of YBa{sub 2}Cu{sub 3}O{sub 7-x} as a function of temperature, for five temperatures ranging from 30K to 300K. The measured 2D-ACAR intensities are interpreted in terms of the electron-positron momentum density obtained within the KKR-band theory framework. The temperature dependence of the 2D-ACAR spectra is used to extract a background corrected'' experimental spectrum which is in remarkable accord with the corresponding band theory predictions, and displays in particular clear signatures of the electron ridge Fermi surface.
Date: December 1, 1991
Creator: Smedskjaer, L. C.; Welp, U.; Fang, Y.; Bailey, K. G. & Bansil, A.
Object Type: Article
System: The UNT Digital Library
Experimental Studies of Pion-Nucleus Interactions at Intermediate Energies. Annual Progress Report (open access)

Experimental Studies of Pion-Nucleus Interactions at Intermediate Energies. Annual Progress Report

This report summarizes the work on experimental research in intermediate energy nuclear physics carried out at New Mexico State University in 1991 under a great from the US Department of Energy. Most of these studies have involved investigations of various pion-nucleus interactions. The work has been carried out both with the LAMPF accelerator at the Los Alamos National Laboratory and with the cyclotron at the Paul Scherrer Institute (PSI) near Zurich, Switzerland. Part of the experimental work involves measurements of new data on double-charge-exchange scattering, using facilities at LAMPF which we helped modify, and on pion absorption, using a new detector system at PSI that covers nearly the full solid-angle region which we helped construct. Other work involved preparation for future experiments using polarized nuclear targets and a new high-resolution spectrometer system for detecting {pi}{sup 0} mesons. We also presented several proposals for works to be done in future years, involving studies related to pi-mesonic atoms, fundamental pion-nucleon interactions, studies of the difference between charged and neutral pion interactions with the nucleon, studies of the isospin structure of pion-nucleus interactions, and pion scattering from polarized {sup 3}He targets. This work is aimed at improving our understanding of the pion-nucleon interaction, …
Date: December 31, 1991
Creator: unknown
Object Type: Report
System: The UNT Digital Library