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Search for the neutrinoless muon decay. mu. /sup +/. -->. e/sup +/. gamma

Description: Separate muon, electron, and tau numbers are conserved in the minimal standard model of electroweak interactions with massless neutrinos. However, in many extensions to the standard model, separate lepton numbers are not expected to be conserved quantities. A new search for muon number non-conserving processes has been undertaken at the Los Alamos Meson Physics Facility (LAMPF), specifically to look for three neutrinoless decay modes of the muon. The search for the decay of a muon to an electro… more
Date: July 1, 1985
Creator: Wilson, S.L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Phenomenology of New Particle Production in Heavy-Ion Collisions

Description: It is shown that the existence of sharp lines in the positron emission spectra observed in low-energy heavy-ion collisions is consistent with the production and subsequent decay of a neutral, pseudoscalar particle with a mass of about 1.6 MeV and a lifetime of about 10/sup -13/ sec. 19 refs., 2 figs.
Date: January 1, 1985
Creator: Balantekin, A. B.; Bottcher, C.; Strayer, M. R. & Lee, S. J.
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Partner: UNT Libraries Government Documents Department
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Surface areas by positron annihilation spectroscopy

Description: Positron annihilation spectroscopy (PAS) is a technique for measuring the length of time that a positron exists after being injected into a specific material. Lifetime measurements have been used for studying defects in metals. These imperfections affect the localized electron densities which in turn influence the lifetime of the positron before annihilation occurs. Electron density differences are also associated with surfaces. This paper describes the PAS technique and shows a correlation bet… more
Date: January 1, 1985
Creator: Dale, J.M.; Rosseel, T.M.; Hulett, L.D.; Venkateswaran, K.; Jean, Y.C. & Fuller, E.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Study of rare muon decay modes with the crystal box

Description: We report on a search for the lepton family-number-nonconserving decays ..mu../sup +/..-->..e/sup +/e/sup -/e/sup +/, ..mu../sup +/..-->..e/sup +/..gamma.., and ..mu../sup +/..-->..e/sup +/..gamma gamma.., using the Crystal Box detector at LAMPF. The experiment was run in the stopped muon channel at LAMPF during the winter and summer of 1984. Muons were stopped in the middle of a detector system consisting of a cylindrical drift chamber, a plastic scintillator hodoscope, and a segmented array o… more
Date: January 1, 1985
Creator: Sandberg, V.; Bolton, R. D.; Bowman, J. D.; Carlini, R. D.; Copper, M. D.; Doung-Van, M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Search for right-handed currents by means of muon spin rotation

Description: A muon spin rotation (..mu..SR) technique has been used to place limits on right-handed weak currents in ..mu../sup +/ decay. A beam of almost 100% polarized 'surface' muons obtained from the TRIUMF M13 beamline was stopped in essentially non-depolarizing >99.99% pure metal foils. The ..mu../sup +/ spins were precessed by 70-G or 110-G transverse fields. Decay e/sup +/ emitted within 225 mrad of the beam direction and with momenta above 46 MeV/c were momentum-analyzed to 0.2%. Comparison of the… more
Date: September 1, 1985
Creator: Stoker, D. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Analytical applications of positrons

Description: In using positrons as analytical tools the experimenter has two quite different options. The first and more obvious is to duplicate electron methods with positrons and see what differences (if any) result. The second is to exploit a unique characteristic of positrons, such as the formation and decay of the positronium atom, to study chemical composition and surface characteristics. Because positrons do not exist freely in our world, they must be obtained from radioactive sources or nuclear inte… more
Date: January 1, 1985
Creator: Dale, J.M.; Hulett, L.D.; Pendyala, S. & Lyon, W.S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Reduction of the trapping of positrons in dislocated single crystals of iron when charged with hydrogen

Description: The positron annihilation measurement was carried out with the pure iron single crystals deformed in various ways before and after hydrogen permeation. The positron trapping intensity was reduced more in the screw dislocation than in the edge dislocation by hydrogen charging. The trap occupancy by hydrogen was very close to the fraction of the reduction in positron trapping intensity.
Date: January 1, 1985
Creator: Park, Y. K.; Waber, J. T. & Snead, C. L. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Determination of edge and screw dislocation density in single crystals of high-purity iron

Description: The trapping of positrons in dislocation-associated traps has been studied and the density of traps has been demonstrated to be in close agreement with the density of dislocations determined by TEM and etch-pit measurements on the same specimens. The specific trapping rates were determined.
Date: January 1, 1985
Creator: Park, Y. K.; Waber, J. T. & Snead, C. L. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Determination of the vacancy formation enthalpy in chromium by positron annihilation

Description: Doppler broadening of the positron annihilation lineshape in 99.99 at. % pure chromium was measured over the temperature range 296 to 2049/sup 0/K. The chromium sample was encapsulated in sapphire owing to its high vapor pressure near melting. Saturation-like behavior of the lineshape was observed near the melting temperature (2130/sup 0/K). A two-state trapping model fit to the data yielded a vacancy formation enthalpy of 2.0 +- 0.2 eV. This result is discussed in relation to extant empirical … more
Date: January 1, 1985
Creator: Loper, G. D.; Smedskjaer, L. C.; Chason, M. K. & Siegel, R. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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[Medium Energy Particle Physics]: Annual Progress Report

Description: Investigations currently carried out by the UCLA Particle Physics Research Group can be arranged into four programs: Pion-Nucleon Scattering; Tests of Charge Symmetry and Isospin Invariance; Light Nuclei (Strong Form Factors of /sup 3/H, /sup 3/He, /sup 4/He; Detailed Balance in pd /r reversible/ /gamma//sup 3/H; Interaction Dynamics); and Search for the Rare Decay /Mu//sup +/ /yields/ e/sup +/ + /gamma/ (MEGA). The general considerations which led to the choice of physics problems investigated… more
Date: October 1, 1985
Creator: Nefkens, B. M. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Study of the equilibrium vacancy ensemble in aluminum using 1D- and 2D-angular correlation of annihilation radiation

Description: One- and two-dimensional angular correlation of positron-electron annihilation radiation (1D and 2D-ACAR) data have been obtained between 293 and 903 K for single crystals of aluminum. The peak counting rates vs temperature, which were measured using the 1D-ACAR technique, provide a model independent value for the temperature dependence of the positron trapping probability. Using these results it is possible to strip out the Bloch state contribution from the observed 2D-ACAR surfaces and then c… more
Date: March 12, 1985
Creator: Fluss, M.J.; Berko, S.; Chakraborty, B.; Hoffmann, K.R.; Lippel, P. & Siegel, R.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Resolvability of positron decay channels

Description: Many data analysis treatments of positron experiments attempt to resolve two or more positron decay or exist channels which may be open simultaneously. Examples of the need to employ such treatments of the experimental results can be found in the resolution of the constituents of a defect ensemble, or in the analysis of the complex spectra which arise from the interaction of slow positrons at or near the surfaces of solids. Experimental one- and two-dimensional angular correlation of annihilati… more
Date: March 7, 1985
Creator: Fluss, M.J.; Howell, R.H.; Rosenberg, I.J. & Meyer, P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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PAS determination of the vacancy formation enthalpy in tungsten

Description: A measurement of the vacancy formation enthalpy in 99.999 wt % pure tungsten under thermal equilibrium conditions was made using the positron anihilation spectroscopy (PAS) Doppler-broadening technique. Temperatures were measured by optical pyrometry, with calibrations against a W(Re) thermocouple, the tantalum melting point, and the power delivered to the sample. A trapping-model analysis of the PAS data from the temperature range 300 to 3633 K yielded a vacancy formation enthalpy of 3.76 +- 0… more
Date: January 1, 1985
Creator: Smedskjaer, L. C. & Chason, M. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Low-temperature positron lifetime and Doppler-broadening measurements for single-crystal nickel oxide containing cation vacancies

Description: Lifetime and Doppler-broadening measurements for positron annihilation in substoichiometric nickelous oxide have been made concomitantly from liquid-helium to room temperature. The concentration of cation vacancies is readily controlled by altering the ambient oxygen pressure while annealing the crystals at 1673/sup 0/K. It was found that neither of the three lifetimes observed or their relative intensities varied significantly with the oxygen pressure, and the bulk rate only increased slightly… more
Date: 1985~
Creator: Waber, James T.; Snead, C. L., Jr. & Lynn, K. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Limits on likesign dilepton production in. nu. /sub. mu. / interactions

Description: We have searched for the production of likesign dilepton events (nu/sub ..mu../ + Ne ..-->.. ..mu../sup -/ + e/sup -/ + ...) in a wideband neutrino beam at Fermilab using the 15-ft bubble chamber. We observe no signal above the background arising from conventional sources. We set 90% confidence level upper limits for the production rates of (nu/sub ..mu../ + Ne ..-->.. ..mu../sup -/ + e/sup -/ + ...)/ (nu/sub ..mu../ + Ne ..-->.. ..mu../sup -/ + ...) < 0.76 x 10/sup -4/ and (nu/sub ..mu../ + Ne… more
Date: August 22, 1985
Creator: Baker, N.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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