He(I)/He(II) photoelectron band intensity ratios for simple organic molecules

Band intensifies in the He(I) and HE(II) photoelectron spectra of some simple organic molecules (methanol, methylamine, formaldehyde, acetaldehyde, formic acid, acetic acid, methyl formate, ethylene, butadiene and methyl isothiocyanate) have been measured. The relative band intensity ratios for a number of ionizations from n and π orbitals are presented.     

Measurement of leptonic branching ratios of the Γ(9.46)

The electronic width Γ _ee and the muonic branching ratioB _μμ =Γ _μμ /Γ_tot of the Γ(9.46) have been measured as Γ _ee =(1.33±0.14) andB _μμ=(2.2±2.0)%. From these values a lower limit of Γ_tot<23keV for the total width of the Γ(9.46) is obtained.     

A relaxation theory of plasma-broadened He II lines

The relaxation theory of plasma line broadening developed by Smith and Hooper, and extended by Smith, is applied to a charged radiator. The 304 Å Lyman alpha line of He II is chosen as an example. The radiator is assumed perturbed only by electronic and ionic electric microfields. The ions are treated in the static approximation. Two-component ion microfield distribution functions that allow for the presence of both He⁺ and He⁺⁺ perturbers are employed. The fact that the radiator is charged complicates the treatment of electron perturbation; two different approaches are included. The first neglects the effect of the charge of the radiator on the perturbing electron and assumes that the perturbing electrons can be represented by momentum wave functions. This method corresponds to Smith's treatment of the electron perturbers in neutral hydrogen. The second includes the effect of the charge of the radiator on the perturbing electrons and represents the perturbing electrons by Coulomb wave functions; this calculation requires evaluation of free-free gaunt factors. The theory, with both the momentum and Coulomb perturber wave functions, predicts a blue asymmetry in the near wings of the line. These two approaches can be compared with the classical path approach of Griem and Shen.     

He(I) and He(II) populations in the Nagoya TPD plasma machine

A collisional-radiative model is used to explain the He(I) population densities observed by Otsuka, Ikee and Ishii in their TPD plasma machine. It is shown that a plasma model, which is partially optically thick to He(II) Lyman radiation, can explain the experimentally observed He(II) population density at T_e=3.17 eV. The agreement between the experimental and calculated He(II) population densities observed by Otsuka and others is shown to be due to an error in their calculations.     

He(I) and He(II) photoelectron spectra of iron tetracarbonyl-olefin complexes

The He(I) and He(II) photoelectron spectra of a series of iron tetracarbonyl—olefin complexes (olefin = acrolein, crotonaldehyde, methyl acrylate, acrylic acid, dimethyl maleate and some dihalogenated ethylenes) are reported. Assignments are proposed, based on differences in intensity between the He(I) and He(II) spectra, in comparison with related compounds and the results of extended CNDO calculations. The electronic structure of the coordinated olefins is discussed.     

He(I) and He(II) photoelectron spectra of some substituted ethylenes

The He(I) and He(II) photoelectron spectra of acrolein, acrylic acid, methyl acrylate, vinyl acetate, acrylamide and some of their methyl-substituted analogues are reported. Detailed assignments are proposed, mainly based on differences in intensity between the He(I) and He(II) spectra, on sum rule considerations and on the results of modified CNDO/S calculations.The assignment criteria are critically evaluated.     

Measurement of Tau branching ratios

Using the data accumulated at LEP in 1989 and 1990 with the ALEPH detector, the inclusive and exclusive branching ratios of the lepton have been measured assuming lepton universality inZ ⁰ decays. The inclusive branching fractions for the decay into one, three, and five charged particles have been determined to be (85.45±0.97)%, (14.35±0.48)%, and (0.10±0.05)%, respectively, in agreement with the world averages. New undetected decay modes are determined to have a branching fraction of less than 2.1% at 95% CL. The measured branching ratios for quasi-exclusive channels are slightly larger than, but consistent with the world averages, except for the modes 3 hadrons+v andhadron+2⁰ v , which are significantly larger. These latter branching ratios have been found to be (9.5±0.7)% and (10.2±1.1)%, respectively. The sum of all the measured quasi-exclusive branching ratios is (100.4±1.8)%. A fully exclusive analysis of modes with neutral pions shows no evidence for new photonic decay modes with a branching fraction limit of 3.4% at 95% CL.Supported by CAICYT, Spain     

He(II) photoelectron spectra of esters

Intensities of X-ray photoelectron transitions from the As 3d level are theoretically analysed taking into account many-electron interactions. The latter interactions profoundly affect the relative intensities of the transitions as well as binding energies. Implications for the surface structure of GaAs are then discussed and in particular we show that As atoms having the same chemical environment are spread over distances into the surface comparable to the interatomic spacing. This supports a recently proposed layer model for the untreated surface of GaAs.     

Population densities of He(I) and He(II) excited states in plasmas

Reduced population coefficients for He(I) and He(II) levels, both for optically thin and partially optically thick conditions, have been calculated from a collisional-radiative model using recent experimental and theoretical cross sections. The calculated population densities are compared with experimental results on helium plasmas. Agreement with experimental results is better at low electron temperatures.     

He(I) and He(II) photoelectron spectra of glycine and related molecules

Photoelectron spectra obtained by He(I) and He(II) excitation of glycine, sarcosine and glycine methyl ester are presented. The p-type bands in the He(I) spectrum of glycine are interpreted in terms of localized molecular orbitals; the C 2s bands are identified in the He(II) spectrum. He(I) spectra of some N-acetylamino acids and of a variety of α-and ω-substituted amino acids are also reported.     

A measurement of K1 (1420) decay branching ratios

The decay branching ratios of K¹⁰ (1420) into K⁺π^?, K⁰π⁺π^? and K¹⁺(892) π^? are measured in the charge exchange reaction $\text{K}{}^{\mathrm{+}}\text{d}\text{→}\text{K}{}^{10}\text{(1420)}\text{pp}{}_{\mathrm{S}}$ using data from a K⁺d bubble chamber experiment at 4.6 GeV/c incident momentum. For the branching ratio $\text{(}\text{K}{}^1\text{(1420) →}\text{K}{}^1\text{(892)π)/(}\text{K}{}^1\text{(1420) →}\text{K}\text{π)}\text{a value of}\text{(0.54 ± 0.16)}$ is obtained. The results are compared with previous measurements.     

Measurement of the ratios of branching fractions and

We report an observation of the decay B(O)(S) --> D(-)(s)pi(+) in pp collisions at radical S = 1.96 TeV using 115 pb(-1) of data collected by the CDF II detector at the Fermilab Tevatron. We observe 83 +/- 11(stat) B(O)(s) --> D(-)(s)pi(+) candidates, representing a large increase in statistics over previous measurements and the first observation of this decay at a pp collider. We present the first measurement of the relative branching fraction Beta(B(O)(s) --> D(-)(s)pi(+))/Beta(B(0) --> D(-)(pi)(+)) = 1.32 +/- 0.18(stat) +/- 0.38(syst). We also measure Beta(B(+) --> D(0)pi(+))/Beta(B(0) -->D(-)pi(+)) = 1.97 +/- 0.10(stat) +/- 0.21(syst), which is consistent with previous measurements.     

Beta-decay branching ratios of 62Ga

Beta-decay branching ratios of ⁶²Ga have been measured at the IGISOL facility of the Accelerator Laboratory of the University of Jyv?skyl?. ⁶²Ga is one of the heavier T _z = 0 , 0⁺ → 0⁺ β -emitting nuclides used to determine the vector coupling constant of the weak interaction and the V_ud quark-mixing matrix element. For part of the experimental studies presented here, the JYFLTRAP facility has been employed to prepare isotopically pure beams of ⁶²Ga . The branching ratio obtained, BR = 99.893(24) %, for the super-allowed branch is in agreement with previous measurements and allows to determine the ft value and the universal Ft value for the super-allowed β -decay of ⁶²Ga .     

A measurement of the Tau topological branching ratios

Using data collected in the DELPHI detector at LEP-1, measurements of the inclusive branching ratios for decay modes containing one, three, or five charged particles have been performed, giving the following results: where h is either a charged orK meson. The first quoted uncertainties are statistical and the second systematic. Received: 17 April 2001 / Published online: 13 June 2001     

Photonuclear reactions from correlated nucleon pairs (II)

A derivation of an expression for the cross section of the photoexcitation of correlated nucleon pairs in a nucleus is given. The final-state wave functions which are obtained from a solution of the Brueckner reaction matrix can be related to the scattering of free nucleons in a vacuum. Some results are presented and include the energy distribution and cross sections of the excited nucleons. An expression for the cross section of the giant dipole resonance is derived purely from the presence of the microscopic two-body forces in nuclei. These cross sections agree with experiment for a particular choice of the final-state single-particle spectrum.     

He(II) photoelectron spectra of the Group IVB tetrachlorides

He(II) photoelectron spectra of the Group IVB tetrachlorides MCl₄ (M = C, Si, Ge, Sn) are reported and compared with He(I) data. The discussion concentrates on the spectral intensity patterns and the nature of the additional structure revealed in the He(II) spectra.