Precise measurement of gamma-ray intensities in the decay of 160·9 day isomeric state in177Lu

The precise gamma-ray intensities of the transitions following the decay of 160·9 day isomeric state in¹⁷⁷Lu have been determined from the gamma-ray spectra measured with three different Ge(Li) detectors. The consistency of the obtained data has been verified by the detailed analysis of the intensity balance on the excited levels of the¹⁷⁷Lu and¹⁷⁷Hf nuclei. In order to describe the experimental values of reduced probabilities of E1 transitions connecting the states of 9/2+ +[624] and 7/2-[514] rotational bands in¹⁷⁷Hf, the necessity to introduce the second order corrections to Alaga rules has been established.The author wishes to thank Dr. J. Adam, head of Nuclear Spectroscopy Department of NPI, for his support, Dr. J. Zvolský and Dr. M. Honusek for valuable discussions.     

Precision measurement of the weak mixing angle in Møller scattering

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (M?ller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.     

Potential of the A 1Σ u + state of He2

The potential of the lowest excited singlet state of He₂ is calculated. The best function includes 209 configurations constructed from 10 σ basis orbitals. Excellent agreement with experimental quantities depending on the shape of the potential near the minimum (equilibrium interatomic separation, vibrational and rotational constants for the lower vibration levels) is obtained. The dissociation energy is 18 600 cm^-1, compared to the experimental 19 910±50 cm^-1. Agreement is not as good for the highest vibrational levels.     

g-factors in the ground state and in the γ-bands in 160,162,164Dy

The g-factors of some members of the ground state band and of the 2⁺ state in the %-vibrational band have been measured in ^160,162,164Dy using the Coulomb Excitation Transient Field technique, induced by ⁵⁸Ni projectiles at 230, 210 and 217 MeV, respectively. The g-factors in the ground state band are consistent with a constant value, while that of the 2⁺_% states is about 20% larger in average than those in the ground state band. Results are discussed in the frame of the systematics in this nuclear region.     

Fine and hyperfine structure in the X2Σ+ state of gas-phase yttrium monoxide

The A²Π_r-X²Σ⁺ visible spectrum of gas-phase yttrium monoxide has been studied at sub-Doppler resolution to obtain information on the spin-rotation and ⁸⁹Y nuclear magnetic hyperfine interactions. The observations were fitted to an effective Hamiltonian model that neglected the nuclear magnetic hyperfine interactions in the excited electronic state. An interpretation of the determined parameters in terms of possible electronic configurations is presented.     

The Hugoniot equation of state of the fluid He+D2 mixtures

The fluid variational theory and effective one-component model have been used to calculate the Hugoniot equation of state (EOS) of fluid He, D2, and He+D2 mixtures with different He:D2 compositions under high pressures and temperatures. An examination of the confidence of above computation is performed by comparing experiment and calculation, in which the similar calculation procedure used for He+D2 is adopted, of He and D2 each, since no experimental data are available to conduct this kind of comparison. Good agreement in both comparisons is found. This fact may be looked as if an indirect positive verification of calculation procedure used here at least in the pressure and temperature domain covered by the experimental data of He and D2 used for comparison, numerically nearly up to 35 GPa and 105K.     

Suppression of the β+-decays of 148Dy, 150Er and 152Yb

We use the quasi-particle random-phase approximation (QRPA) with a realistic effective nucleon-nucleon interaction to describe the positron β⁺-decay of the neutron-deficient single-closed-shell nuclei ¹⁴⁸₆₆Dy₈₂, ¹⁵⁰₆₈Er₈₂ and ¹⁵²₇₀Yb₈₂ . In this framework we study the effect of the particle-particle interaction strength on the β⁺-transition strengths in these nuclei. We are able to reproduce the experimental strengths by reasonable values of the interation parameters, not very different from nucleus to nucleus.     

Asymmetry measurement of the polarized Σ+p elastic scattering and the hyperon-nucleon spin-orbit interaction

In order to study the hyperon-nucleon spin-orbit interaction, asymmetries of the polarized Σ⁺ elastic scattering on protons have been measured. The polarized hyperons were produced through the p(π⁺, K⁺) Σ⁺ reaction in a liquid-scintillator active target, and tracks of Σ⁺p scattering events were recorded with a newly developed track detector named SCITIC (scintillating track image camera). Although analyses of 10 times more data with more sophisticated data-taking systems and more elaborated analyzing tools are under way, data from an early stage of this experiment indicate a large Σ⁺p spin-orbit interaction in contrast to the case of the small ΛN spin-orbit interaction. Received: 27 May 2002 / Accepted: 23 July 2002 / Published online: 19 November 2002 RID="a" ID="a"e-mail: nakai@post.kek.jp Communicated by Th. Walcher     

Contribution of the lowest 1+ intermediate state to the 2νββ-decay amplitude

The half-life with respect to two-neutrino double-beta (2νββ) decay to the final ground state is calculated under the assumption of single-state dominance. To the best of our knowledge, the energy denominators of perturbation theory are considered for the first time without invoking any approximation. The results obtained for the experimentally interesting A=100, 110, 114, 116, and 128 nuclear systems are presented.     

Laser-induced-fluorescence Fourier transform spectrometry of the XOg+ state of I2: Extensive analysis of the BOu+ → XOg+ fluorescence spectrum of 127I129I and 129I2

An extensive rotational analysis of the vibrational levels of the XO_g⁺ state of ¹²⁷I¹²⁹I (5 ≤ v″ ≤ 110) and ¹²⁹I₂ (4 ≤ v″ ≤ 108) has been done from laser-induced-fluorescence analyzed with a Fourier transform spectrometer. The usual Dunham relationships are checked. For the range explored the lines can be recalculated with an accuracy better than 0.010 cm⁻¹ and even 0.005 cm⁻¹ for low J values. Checks are done from absolute hyperfine measurements.     

Observation of the decay Ks → 2γ and measurement of the decay rates KL → 2γ and KS → 2γ

The decay rates of K_L → 2γ and K_S → 2γ have been measured at the CERN SPS. The results are Γ(K_L→2γ)/χ(K_L→2π₀)=0.632±0.004±0.008 and Γ(K_S→2γ)/Γ(K_L→2γ)=2.3 ±1.0±0.4. This is the first observation of K_S→2γ decays.     

Precision calculation of processes used for luminosity measurement at the ZEUS experiment

The process pe ^±→pe ^± γ with the photon emitted along the electron beam axis is used for luminosity measurement at HERA. In this paper the process is calculated including one-loop QED radiative corrections. In the ZEUS experiment, both the electron and the photon can be detected. Therefore both photon and electron spectra with and without the γ–e coincidence are analyzed. We also calculate the process pe ^±→pe ^± l ⁻ l ⁺ which contributes to the background in the electron tagger.     

Kagomé ice state in the dipolar spin ice Dy2Ti2O7

We have investigated the kagomé ice behavior of the dipolar spin-ice compound Dy2Ti2O7 in a magnetic field along a [111] direction using neutron scattering and Monte Carlo simulations. The spin correlations show that the kagomé ice behavior predicted for the nearest-neighbor interacting model, where the field induces dimensional reduction and spins are frustrated in each two-dimensional kagomé lattice, occurs in the dipole interacting system. The spins freeze at low temperatures within the macroscopically degenerate ground states of the nearest-neighbor model.     

The B2Σ+ state of zinc deuteride

Conventional high-resolution photographic spectroscopy has been employed to study the B²Σ-X²Σ emission system of zinc deuteride in the region 280–370 nm. The B-X system of ZnD is reported for the first time and 17 such bands have been rotationally analyzed. Many local rotational perturbations have been found in the B state and are attributable to interactions with the A²Π state. The rotational and vibrational data for ZnH (after Stenvinkel) and ZnD are complementary and enable the RKR curve for the B state to be mapped with reasonable accuracy for almost 10 000 cm⁻¹. B-X Franck-Condon factors for ZnH and ZnD are also reported.