[en] Goldhaber and Scharff-Goldhaber have carried out an experiment studying the nature of β-rays emitted by the radioactive nucleus which was based on the Pauli exclusion principle. Davies and Grace have repeated that experiment and reported that less than one captured X-ray was observed for 4 x 10⁵ β-rays. But the sensitivities of these experiments were low. The development of experimental techniques including a strong β-ray source and a high resolution X-ray detector enables us to perform an ultra-high sensitive experiment to test the identity of β-rays with atomic electrons. Here we report our experimental result which shows that less than 1.4x10^-13 (95% confidence level) of the tritium β-rays stopped in the erbium target are captured into the K shell of these atoms. This limit is about seven orders of magnitude lower than the previous experiment. (orig.)

[en] The operation of a thin gap multiwire chamber with a CO₂/n-pentane mixture is described for different wire diameters, gap distances and cathode material. (orig.)

[en] Using a Compton polarization analyzer the linear polarization of one photon from the three-photon decay of orthopositronium under several geometrical conditions has been measured. For α₁=45⁰, 75⁰, 105⁰ and 120⁰, the ratio of the number of photons Compton-scattered parallel to the plane of the three photons to the number scattered perpendicular to that plane was found to be 1.20±0.03, 1.53±0.03, 1.76±0.06 and 1.86±0.06, respectively. The linear polarization of the photons along the plane of the three photons was determined as 0.15±0.04, 0.33±0.04, 0.49±0.04 and 0.51±0.05, respectively. This result is in agreement with theoretical predictions. (orig.)

[en] High energy electrons emitted by water plasmas produced by a single or a multiple laser pulse are investigated. The multipulse mode greatly enhances the generation and the temperature of hot electrons. Directional emission of high energy electrons over 25 keV is observed in two symmetric directions with respect to the laser axis and at 46 degree sign from the directions of the laser electric field. Two-dimensional particle-in-cell simulations reproduce well the experimental results and indicate that the acceleration mechanism of the high energy electrons is due mainly to the resonance absorption at the edge of the spherical droplets formed by the leading pulse

[en] An analytical model for solute advection and dispersion in a two-layered liner consisting of a geosynthetic clay liner (GCL) and a soil liner (SL) considering the effect of biodegradation was proposed. The analytical solution was derived by Laplace transformation and was validated over a range of parameters using the finite-layer method based software Pollute v7.0. Results show that if the half-life of the solute in GCL is larger than 1 year, the degradation in GCL can be neglected for solute transport in GCL/SL. When the half-life of GCL is less than 1 year, neglecting the effect of degradation in GCL on solute migration will result in a large difference of relative base concentration of GCL/SL (e.g., 32% for the case with half-life of 0.01 year). The 100-year solute base concentration can be reduced by a factor of 2.2 when the hydraulic conductivity of the SL was reduced by an order of magnitude. The 100-year base concentration was reduced by a factor of 155 when the half life of the contaminant in the SL was reduced by an order of magnitude. The effect of degradation is more important in approving the groundwater protection level than the hydraulic conductivity. The analytical solution can be used for experimental data fitting, verification of complicated numerical models and preliminary design of landfill liner systems. - Highlights: •Degradation of contaminants was considered in modeling solute transport in GCL/SL. •Analytical solutions were derived for assessment of GCL/SL with degradation. •Degradation in GCL can be ignored as half-life is larger than 1 year. •Base concentration is more sensitive to half-life of SL than to permeability of SL

[en] A prototype of a gas sampling uranium module of the L3 hadron calorimeter was built and subsequently tested with pion beams of energies between 4 and 20 GeV. The construction of the proportional chambers, the assembling of the module, the readout electronics, and the beam test are briefly described. The energy resolution of the calorimeter module alone was measured to be 30.5±3% at 6 GeV, 21±2% at 10 GeV and 18±2% at 20 GeV. For the module together with a BGO crystal matrix in front, the resolution was 29±3% at 4 GeV, 21±2% at 10 GeV, and 17±2% at 20 GeV. (orig.)

[en] Polycrystalline CoFe_2O_4 thin films were deposited on Si (100) substrates by chemical solution deposition with and without magnetic annealing. Magnetic field directions were applied parallel and perpendicular to the film surface during the magnetic annealing process. The variations of strain, microstructure and magnetic anisotropy of the films caused by the magnetic annealing are investigated. The results show that the film densification is promoted and grain morphology is changed by the magnetic annealing, which can be attributed to the promoting effect of magnetization force on the grain growing and grain boundary diffusing. Magnetic measurements indicate the enhancement of anisotropy and saturation magnetizations of the polycrystalline CoFe_2O_4 after magnetic annealing. Furthermore, the rotation of easy axis along the field direction, the increased occupation of Co"2"+ ions at B sites and the additional strain induced by the magnetic field are considered as the main reasons of the increased magnetic anisotropy. - Highlights: • CFO films were annealed in magnetic field with parallel and vertical directions. • The film densification and grain size were changed by the applied magnetic field. • A higher saturation magnetization is obtained under magnetic annealing. • The enhanced magnetic anisotropy is observed after magnetic annealing

[en] Single-phase Bi_0.85La_0.15FeO₃ ceramics were synthesized under various magnetic fields (H_a=0 T, 3 T, 5 T). Substantially reduced leakage current and hence modified ferroelectric (FE) properties were obtained with magnetic field annealing (MA). The largest magnetization and lowest leakage current with large FE polarization (P_r∼33 μC/cm²) were found in the sample annealed with H_a=3 T. Great changes were also observed in the Raman spectra. All the observed features originate mainly from the different FE domain wall structures induced by MA. These results demonstrate that MA is an effective way to tune the multiferroic and magnetoelectric properties in BiFeO₃-based materials. - Graphical abstract: Bright field TEM micrograph of the representative domain structures in the samples (a) BLF0, (b) BLF3 and (c) BLF5. Highlights: ► Bi_0.85La_0.15FeO₃ ceramics were synthesized under various magnetic fields. ► Substantially reduced leakage current with improved ferroelectricity were obtained. ► Enhanced magnetization with moderate annealing magnetic field

[en] We investigate the angular distribution and the energy spectrum of hot electrons emitted from ethanol droplets irradiated by linearly polarized 150-fs laser pulses at an intensity of 10¹⁶ W/cm². Two hot electron jets symmetrically with respect to the laser propagation direction are observed within the polarization plane. This is due to the spherical geometry of droplets in the intense laser field. The maximum energy of the hot electrons is found to be more than 600 keV. Particle-in-cell simulations suggest that the resonance absorption is the main mechanism for hot electron generation

[en] The design and the mass production of the proportional wire chambers for the barrel part of the uranium-gas sampling hadron calorimeter of the L3 detector at the CERN Large Electron-Positron storage ring (LEP) are described. The chambers meet the specific requirements arising from the limited space available to the calorimeter, the radioactivity of uranium, and the physics criteria of good energy and position resolution for incident hadrons. The mass production techniques employed ensured that all of the 371664 chamber cells have uniform response (with 5% accuracy) to ionizing particles. Over 8000 chambers of the same design, in 53 different sizes, were manufactured and tested at the ITEP (Moscow), at the University of Michigan (Ann Arbor) and at the IHEP (Beijing). (orig.)