9 Matching Results

Results open in a new window/tab.

Observation of excited H/sup 0/ atoms produced by relativistic H/sup /minus// ions in carbon and formvar foils (open access)

Observation of excited H/sup 0/ atoms produced by relativistic H/sup /minus// ions in carbon and formvar foils

We have measured the relative yield of several low-lying excited states of neutral hydrogen atoms produced by the passage of 226-MeV and 581-MeV H/sup /minus// ions through thin carbon foils and a tilted formvar foil. The relative yields of H/sup /minus///sub /asterisk//(n = 2,3, 4) were measured for 17 different carbon foils ranging in thickness from 662 /angstrom/ to 5386 /angstrom/ at 581 MeV. The relative yield of H/sup 0//sup /asterisk//(n = 2) was also measured for these carbon foils at 226 MeV. These data exhibit a significant deviation from a simple yield curve indicating that a more complex mechanism than has previously been thought is responsible for producing the excited states. The relative yields of H/sup 0//sup /asterisk//(n = 2,3) were measured for a tilting formvar foil at 226 MeV; unexplained dips appear at incidence angles of /theta/ /approx/ 12/degree/ and /theta/ /approx/ 15/degree/ in the yield of n=2 and n=3 states, respectively. 19 refs., 7 figs., 1 tab.
Date: February 8, 1989
Creator: Mohagheghi, A. H.; Bryant, H. C.; Harris, P. G.; Tang, C. Y.; Quick, C. R.; Reeder, R. A. et al.
System: The UNT Digital Library
Electroweak symmetry breaking studies at the pp colliders of the 1990's and beyond (open access)

Electroweak symmetry breaking studies at the pp colliders of the 1990's and beyond

Within the conventional framework of a spontaneously broken gauge theory, general principles establish that the electroweak symmetry is broken by a new force that may be weak with associated new quanta below 1 TeV or strong with quanta above 1 TeV. The SSC parameters, ..sqrt..s = 40 TeV and L = 10/sup 33/ cm/sup /minus/2/s/sup /minus/1/, define a minimal facility with assured capability to observe the signals of symmetry breaking by a strong force above 1 TeV. Foreseeable luminosity upgrades would not be able to compensate a much lower collider energy for these physics signals. If the strong WW scattering signal were seen at the SSC in the 1990's it would provide a clear imperative for a collider with the physics reach of the ELOISATRON to begin detailed studies of the new force and quanta early in the next century. 35 refs., 7 figs., 4 tabs.
Date: March 8, 1989
Creator: Chanowitz, Michael S.
System: The UNT Digital Library
The characterization of Nb/sub 3/Sn superconductors for use in magnets of 19 T and greater (open access)

The characterization of Nb/sub 3/Sn superconductors for use in magnets of 19 T and greater

Increased resolution of NMR spectrometry will require the use of very high field Nb/sub 3/Sn superconducting magnets. Here we report the results of our investigation into mechanical and temperature effects on internal-Sn superconductors similar to those proposed for use in a 900 MHz, 21 T NMR magnet system. Thermal precompression was found to be about 0.225%, and the irreversible strain was about 0.8%. Fatigue degradation was not observed at cyclic intrinsic strains below 0.575%. Additions of reinforcing steel in cable conductors was found to reduce the critical current by as much as 50% compared to similar, unreinforced cables. Reduction of the testing temperature to 2.3 K did not increase the critical current in steel-reinforced cables to a level significantly above that of unreinforced samples. 4 refs., 3 figs., 1 tab.
Date: August 8, 1989
Creator: Summers, L. T.; Strum, M. J. & Miller, J. R.
System: The UNT Digital Library
The International Thermonuclear Experimental Reactor (ITER): Design and materials selection (open access)

The International Thermonuclear Experimental Reactor (ITER): Design and materials selection

The success of ITER relies on aggressive design of the superconducting magnet systems. This design emphasized high radiation-damage tolerance, acceptance of high nuclear heat loads, and high operational stresses in the Toroidal Field (TF) magnets. The design of the Central Solenoid (CS) magnets, although they will be well shielded from the plasma, is equally aggressive due to the need for very high magnetic fields (14 T) and long term operation at high cyclic stresses. Success of these magnet designs depends, in part, on sound selection and fabrication of materials for structural, superconducting, and insulating components. Here we review the design of ITER and the selection of structural materials for some of the systems that will operate at cryogenic temperatures. In addition we will introduce some of the data that the materials selection is based on and suggest opportunities for future research in support of ITER. 10 refs., 1 fig., 4 tabs.
Date: August 8, 1989
Creator: Summers, L. T.; Miller, J. R. & Heim, J. R.
System: The UNT Digital Library
Geometric continuum regularization of quantum field theory (open access)

Geometric continuum regularization of quantum field theory

An overview of the continuum regularization program is given. The program is traced from its roots in stochastic quantization, with emphasis on the examples of regularized gauge theory, the regularized general nonlinear sigma model and regularized quantum gravity. In its coordinate-invariant form, the regularization is seen as entirely geometric: only the supermetric on field deformations is regularized, and the prescription provides universal nonperturbative invariant continuum regularization across all quantum field theory. 54 refs.
Date: November 8, 1989
Creator: Halpern, M.B. (California Univ., Berkeley, CA (USA). Dept. of Physics)
System: The UNT Digital Library
Hadron-hadron physics at high energy and luminosity (open access)

Hadron-hadron physics at high energy and luminosity

I review some recent theoretical issues relevant to the physics of hadron-hadron collisions. I discuss processes where either energy or luminosity is the most important feature and emphasize the need for experiments at luminosities of 10{sup 33}cm{sup -2}sec{sup 1} if the full range of physics options is to be thoroughly explored. 22 refs., 10 figs.
Date: November 8, 1989
Creator: Hinchliffe, I.
System: The UNT Digital Library
Log(s) physics results from CDF (open access)

Log(s) physics results from CDF

The Collider Detector at Fermilab (CDF) is a large, azimuthally symmetric detector designed to study {bar p}p interactions at the Fermilab Tevatron Collider. Results are presented from data taken with a minimum bias trigger at {radical}s = 630 and 1800 GeV during the 1987 run. The topics include the current analysis of dn/d{eta} and some very preliminary results on short range pseudorapidity correlations and Bose-Einstein correlations. 7 refs., 5 figs., 2 tabs.
Date: November 8, 1989
Creator: unknown
System: The UNT Digital Library
Application of analytical methods for jointed rock as part of a drift design methodology for the Yucca Mountain Project (open access)

Application of analytical methods for jointed rock as part of a drift design methodology for the Yucca Mountain Project

The Yucca Mountain Project, managed by the Nevada Operations Office of the US Department of Energy (DOE), is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain, on and adjacent to the Nevada Test Site. Excavation stability will be required during construction, waste emplacement, retrieval (if required), and closure, covering a period of approximately 100 years. In order to incorporate a means of evaluating excavation stability in the design process, a drift design methodology has been developed. This methodology uses both empirical and analytical methods in conjunction with detailed descriptions of site conditions to evaluate a proposed design. At present, the emphasis is on analytical numerical methods because of the limited experience, in tuff at elevated temperatures. This paper describes the proposed methods for analysis of systematically jointed, isotropically jointed, and widely spaced, discretely jointed rock masses. Loads resulting from in situ stress, thermal expansion, and seismic events are considered. Criteria for strength and failure of intact rock and the rock mass are applied to analysis results to assess the stability of proposed drift designs and to guide the design of the ground support system.
Date: December 8, 1989
Creator: Costin, L. S.; Bauer, S. J. & Hardy, M. P.
System: The UNT Digital Library
A new model for solvent extraction in columns (open access)

A new model for solvent extraction in columns

A new model was developed for analyzing solvent extraction processes carried out in columns. Each column is treated as a series of well-defined equilibrium stages where the backmixing (other-phase carryover) between stages can be large. By including all mass transfer effects in the backmixing value, the same number of stages can be used for all extracted components no matter what their distribution coefficients. This greatly simplifies the calculations required when modeling multicomponent solvent extraction processes. Initial testing shows the new model to be better than either the Height of an Equivalent Theoretical Plate (HETP) or the Height of a Transfer Unit (HTU) method.
Date: December 8, 1989
Creator: Leonard, R. A.; Regalbuto, M. C.; Chamberlain, D. B. & Vandegrift, G. F.
System: The UNT Digital Library