Branching fractions of tau leptons to three charged hadrons

From electron-positron collision data collected with the CLEO detector operating at Cornell Electron Storage Ring near sqrt[s]=10.6 GeV, improved measurements of the branching fractions for tau decays into three explicitly identified hadrons and a neutrino are presented as B(tau(-)-->pi(-)pi(+)pi(-)nu(tau))=(9.13+/-0.05+/-0.46)%, B(tau(-)-->K-pi(+)pi(-)nu(tau))=(3.84+/-0.14+/-0.38) x 10(-3), B(tau(-)-->K-K+pi(-)nu(tau))=(1.55+/-0.06+/-0.09) x 10(-3), and B(tau(-)-->K-K+K-nu(tau))<3.7 x 10(-5) at 90% C.L., where the uncertainties are statistical and systematic, respectively.     

Measurement of theΞ - p elastic cross section at 102 and 135 GeV/c

TheΞ ^- p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.012, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)^?2 at 102 GeV/c and 8.2 ±0.5(GeV/c)^?2 at 135 GeV/c. The corresponding total elastic cross sections areσ _el=4.9±0.7 mb andσ _el=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models.     

Two-proton pickup in the zirconium region using the (6Li, 8B) reaction

Spectra at θ_lab = 8° have been measured for the ^{92, 94, 96, 98, 100}Mo(⁶Li, ⁸B)^{90, 92, 94, 96, 98}Zr and ^{90, 92, 94}Zr(⁶Li, ⁸B)^{88, 90, 92}Sr two-proton pickup reactions at 90 MeV. The strongest transitions to levels in the Zr isotopes are the 0⁺ → 0⁺ transitions to the g.s. and first excited 0⁺ states. The salient feature of the five Zr spectra is the large increase in 0⁺₂ transition strength relative to that of the g.s. which is observed in the two heaviest isotopes, ^{96, 98}Zr. In ⁹⁰Zr, the 0⁺₂ transition is weak whereas it is the dominant transition in ⁹⁸Zr with twice the g.s. strength. These large variations in relative cross section, which are reproduced by DWBA calculations, are attributed to changing g.s. proton configurations in Zr. In the Sr spectra, which are distinctly different from the Zrspectra, the strongest transitions to excited states are to 2⁺ rather than 0⁺ states. The (⁶Li, ⁸B) reaction seems to be adequately described as a one-step cluster transfer of a T = 1, S = 0 proton pair. The suitability of this reaction for measurements of two-proton pickup is discussed.     

The point of zero charge of manganese dioxides

Chemically prepared δ-MnO₂ (sample A) was characterised by chemical and size analyses and by t.g.a. and d.t.a. Sample B was the well-characterised International Common Sample ICS 5, which is a chemical λ-MnO₂. Potentiometric acid/base titration of sample A gave a point of zero charge, p.z.c., at pH 3.3±0.5, which is close to the isoelectric point obtained from sedimentation-coagulation results. Fast acid/base titration of sample B gave a p.z.c. at pH 5.9±0.3, which is close to the isoelectric point estimated from electrophoretic measurements. Temperature in the range 298–346 K (25°–73°C) had a minor effect on the titration results.     

Enhancement of superconductivity by quasiparticle tunneling

Increases of the superconducting energy gap Δ have been measured using an entirely new mechanism of enhancement. Instead of microwave or phonon irradiation, the new mechanism uses quasiparticle tunneling between two identical superconductors at voltages less than 2Δ. A decrease in the quasiparticle density accompanies the increase in Δ. This mechanism has important advantages in making quantitative comparisons with theory.