Measurement of the W-->taunu production cross section in pp collisions at square root s=1.8 TeV

We report on a measurement of sigma(pp-->W+X)B(W-->taunu) in pp collisions at sqrt[s]=1.8 TeV at the Fermilab Tevatron. The measurement is based on an integrated luminosity (lum) of 18 pb-1 of data collected with the D0 detector during 1994-1995. We find that sigma(pp-->W+X)B(W-->taunu)=2.22+/-0.09 (stat)+/-0. 10 (syst)+/-0.10 (lum) nb. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the W boson, gWtau/gWe, be unity. We find gWtau/gWe=0.980+/-0.031, in agreement with lepton universality.     

Studies in nickel(IV) chemistry. Part 6. Kinetics of electron transfer from phenylhydrazine to tris-(dimethylglyoximato) nickelate(IV) in aqueous medium

The kinetics of electron transfer from phenylhydrazine(S) to tris-(dimethylglyoximato) nickelate(IV), Ni(dmg) (dmg^2? = dimethylglyoximate dianion), have been studied in aqueous medium in the range of 6.21 ? pH ? 12.2. The kinetics exhibit a pseudo-first-order disappearance of Ni(dmg) when excess S is present. The pseudo-first-order rate constants k_obs are almost linearly dependent on [S]₀ for varying concentrations of the reductant. At constant [S]₀, the k_obs?pH profile is U shaped. The k_obs values register a decrease as the [H⁺] is increased in the pH range of ∽12.2–9.5, remain almost constant (minimum) in the range of ∽9–8, and then again linearly increase as [H⁺] is increased in the pH range of ∽7–6.21. Results are interpreted in terms of a probable mechanism involving outer-sphere electron transfer from the phenylhydrazine and phenylhydrazinium cation species to the unprotonated and one-protonated species of the Ni(IV) complex. The reduction rate appears to be dependent on the nature of the species (unprotonated and one-protonated) of the oxidant Ni(IV) complex. The phenylhydrazinium cation reduces the Ni(IV) complex at least one order of magnitude faster than does the neutral reductant species. The major product of the oxidation of phenylhydrazine by the Ni(IV) complex is 4-hydroxyazobenzene with a small amount of phenol.     

Studies in nickel(IV) chemistry. Kinetics of the Cu(II) ion-mediated acid decomposition of tris(dimethylglyoximato) nickelate(IV) in aqueous acidic medium

Kinetics of the Cu(II) ion-mediated acid decomposition of tris (dimethylglyoximato)nickelate(IV), Ni(dmg)₃^2? (dmg^2? = dimethylglyoximate dianion), are reported in aqueous medium in the range of 3.6 ? pH ? 6.6 at 35°C and μ = 0.57 M. The pseudo-first-order rate constants of the disappearance of Ni(IV) k_obs(M) satisfy the equation where k_ad refers to the pseudo-first-order rate constants for the proton-assisted decomposition of the Ni(IV) complex determined independently and is a function of [H⁺], and k_dec(M) to that for the Cu(II) ion-mediated route and is a function of [H⁺] and [Cu²⁺]. Both k_obs(M) and k_dec(M) are found to increase with increasing [Cu(II)]₀, tending to attain limiting values at higher relative [Cu(II)]₀. At low [Cu(II)]₀ the k_dec(M) is found to register a decrease with increasing pH in the pH range of 3.6–4.4, then an increase in the range of 4.4–5.76, and again a decrease in the range of 5.76–6.6. Results on the Cu(II) ion-mediated acid decomposition are interpreted in terms of a probable mechanism involving pH-dependent adduct formation equilibria involving the one-protonated and the two-protonated species of Ni(IV) and the various species of Cu(II) ion in the media, followed by rate-determining acid decomposition of the adduct(s) to give Ni(II) aq. and Cu(dmgH)₂. While the two-protonated Ni(IV) complex apparently reacts about five orders of magnitude faster than the one-protonated species, the aquacopper(II) reacts about two orders of magnitude slower than the hydroxoaquacopper(II).     

Dynamics of H2O molecules in ferroelectric K4Fe(CN)6 · 3H2O

The infrared spectrum of potassium ferrocyanide trihydrate has been recorded both in the para and ferroelectric phases. From a combined study of the IR and Raman spectra, it is concluded that there are two sets of water molecules present in the lattice, one set being involved in stronger hydrogen bonding than the other. The ferroelectric transition appears to be associated with an ordering of the water dipoles.     

Quasi-model-independent search for new high p(T) physics at D0

We apply a quasi-model-independent strategy ("Sleuth") to search for new high p(T) physics in approximately 100 pb(-1) of pp collisions at square root of (s) = 1.8 TeV collected by the D0 experiment during 1992-1996 at the Fermilab Tevatron. We systematically analyze many exclusive final states and demonstrate sensitivity to a variety of models predicting new phenomena at the electroweak scale. No evidence of new high p(T) physics is observed.     

Search for doubly charged higgs boson pair production in the decay to mu(+)mu(+)mu(-)mu(-) in pp collisions at sqrt[s]=1.96 TeV

A search for pair production of doubly charged Higgs bosons in the process pp -->H(++)H(--) -->mu(+)mu(+)mu(-)mu(-) is performed with the D0 run II detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive dimuon data collected at an energy of sqrt[s]=1.96 TeV, corresponding to an integrated luminosity of 113 pb(-1). In the absence of a signal, 95% confidence level mass limits of M(H(+/-+/-)(L))>118.4 GeV/c(2) and M(H(+/-+/-)(R))>98.2 GeV/c(2) are set for left-handed and right-handed doubly charged Higgs bosons, respectively, assuming 100% branching into muon pairs.     

Measurement of k0-Factors in Prompt Gamma-Ray Neutron Activation Analysis

The guided thermal neutron beam at 100 MW Dhruva research reactor facility of Bhabha Atomic Research Centre (BARC) was used to carry out prompt gamma-ray neutron activation analysis (PGNAA). The prompt k ₀-factors have been determined for the isotopes of the elements H, B, K, Co, Cu, Ca, Ti, Cr, Cd, Ba, Hg and Gd with respect to 1951 keV gamma-line of ³⁶Cl. The prompt k ₀-factors for H, Cl and Cu were also measured with respect to the 1381 keV gamma-line of ⁴⁹Ti. Different samples like NH₄Cl, Ti metal, cobalt chloride and other stoichiometric compounds and pure metals were used for this purpose. Prompt gamma-rays were accumulated using a 22% HPGe detector connected to a PC based 8k MCA in single mode counting. The energy calibration in the range of 100–8500 keV was carried out using gamma-rays from ¹⁵²Eu and ⁶⁰Co, and the prompt gamma-rays from ³⁶Cl whereas the absolute detection efficiency for this energy range was determined using ¹⁵²Eu and prompt gamma-rays from ³⁶Cl and ⁴⁹Ti.     

Solvent extraction of La(III) using Cyanex 921 in petrofin and modelling of data by linear and nonlinear techniques

Journal of Radioanalytical and Nuclear Chemistry - Influence of various parameters affecting the extraction of La(III) from acidic nitrate medium has been analysed. The extraction of 99.1% La(III)...