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1989

Physics

Dissertations, Theses, and Masters Projects

Articles 1 - 4 of 4

Full-Text Articles in Physical Sciences and Mathematics

Local Density Approximation Study Of Transition Andf-Electron Materials, Zhi Wei Lu Jan 1989

Local Density Approximation Study Of Transition Andf-Electron Materials, Zhi Wei Lu

Dissertations, Theses, and Masters Projects

The local density approximation (LDA) has been proved to be a powerful starting point for calculating electronic and structural properties for many real materials. We have studied the effects of particular forms of exchange-correlation potentials (the X{dollar}\alpha{dollar} and Hedin-Lundqvist form) upon the structural properties for the 3d Ti and 4d Zr using a highly accurate linearized augmented plane wave (LAPW) method. The calculated equilibrium volumes differ by 6-8% for these two forms (with X{dollar}\alpha{dollar} results in better agreement with experiment) with proportional differences in other structural properties, which we take to be an indication of the intrinsic reliability of the …


A Search For The Rare Decay Kaon(L) Going To Muon/Electron, John Fred Ginkel Jan 1989

A Search For The Rare Decay Kaon(L) Going To Muon/Electron, John Fred Ginkel

Dissertations, Theses, and Masters Projects

A sensitive search has been carried out for the rare decay $\rm K\sb{L}\to\mu e$. This decay violates conservation of separate lepton-number and thus is forbidden in the Standard Model of electro-weak interactions. Many new models have been proposed which could permit this process. The data were collected in the B5 beamline of the Alternating Gradient Synchrotron facility at the Brookhaven National Laboratory during the Spring, 1988 slow-extracted beam running period. The experiment was sensitive to approximately fifty million $\rm K\sb{L}\to\pi\pi$ decays. No $\rm K\sb{L}\to\mu e$ candidate events were detected. The 90% confidence level upper limit for the branching ratio is …


A Measurement Of The Decay Rate For The Process Kaon(L) Going To Positive Muon Negative Muon, Christopher John Kenney Jan 1989

A Measurement Of The Decay Rate For The Process Kaon(L) Going To Positive Muon Negative Muon, Christopher John Kenney

Dissertations, Theses, and Masters Projects

A sample of 87 events of the GIM suppressed decay K$\sb{\rm L} \to \mu\sp+\mu\sp-$ were observed in an experiment performed in 1988 at the Brookhaven National Laboratory. Concurrently, 8,887 examples of the CP-violating decay K$\sb{\rm L} \to \pi\sp+\pi\sp-$ were also seen. The apparatus consisted of a double-magnet spectrometer as well as electromagnetic and muon detector systems. From the previously measured branching ratio for K$\sb{\rm L} \to \pi\sp+\pi\sp-$ and the different instrumental acceptances of the detector for the two decays, the data sample was normalized to the effective number of K$\sb{\rm L}$ decays observed. A value for the ratio (K$\sb{\rm L} …


Nmr On Single Crystals Of Potassium Cyanogen Bromide (A Measurement Of The Orientational Probability Distribution Function Of The Negatively Charged Cyanogen Ion), Jeffrey Howard Walton Jan 1989

Nmr On Single Crystals Of Potassium Cyanogen Bromide (A Measurement Of The Orientational Probability Distribution Function Of The Negatively Charged Cyanogen Ion), Jeffrey Howard Walton

Dissertations, Theses, and Masters Projects

Single crystals of K(CN)$\sb{\rm x}$/(Br)$\sb{\rm 1-x}$ enriched in $\sp{15}$N have been studied by $\sp{15}$N NMR. Because of the anisotropic chemical shift, the NMR frequency spectrum of the orientational glass state reflects the distribution of cyanide orientations. By studying the spectrum at many orientations of each crystal, the orientational probability distribution function P($\Omega$) has been determined for x = 0.50 and for x = 0.20. The probability function is largest along the (100) directions, intermediate in the (110) directions, and nearly 0 along the (111) directions. The NMR determined P($\Omega$) is presented graphically and in terms of the Kubic Harmonic functions. …