Study of Thermal Desorption of Helium from Hydrogenated Zirconium

A new method prepared for helium and hydrogen co-containing Zr films is presented to simulate aging metal tritides, in which direct current magnetron sputtering with a He/H/Ar mixture is used. The retained amount and depth profiles of helium and hydrogen are determined by elastic recoil detection analysis. Thermal desorption spectrometry is applied to investigate He thermal release and the effect of hydrogen. It is found that the hightemperature peaks with a large mount of helium release obviously shifted toward lower temperature at high hydrogen concentration, especially at the hydride transformation region, and that the shapes of the release peaks also changed due to the additional hydrogen. However, at the low-temperature releasing region the peak intense decreases when phase transformation takes place. The mechanism of helium thermal release and the effect of hydrogen are also discussed.     

Photoproduction of πmesons from nuclei

Photoproduction of neutral pions from nuclei (carbon, calcium, niobium, lead) has been studied for incident-photon energies from 200 MeV to 800 MeV with the TAPS detector using the Glasgow photon tagging spectrometer at the Mainz MAMI accelerator. Data were obtained for the inclusive photoproduction of neutral pions and the partial channels of quasifree single- , double- , and photoproduction. They have been analyzed in terms of the in-medium behavior of nucleon resonances and the pion-nucleus interaction. They are compared to earlier measurements from the deuteron and to the predictions of a Boltzmann-Uehling-Uhlenbeck (BUU) transport model for photon-induced pion production from nuclei.PACS: 13.60.Le Meson production - 25.20.Lj Photoproduction reactions     

Highlight model of echoes from sonar targets

I.IntroductionTheecho-rangingapproachistheonlycffectiveapproachfordetectionandidentifi-cationofunderwatertargetifitisasilcntobkct.Echoformationisaphysicalprocessinwhichthetargetisexcitcdbyincidentwavc.Byechothecharactcristicinformationsoftargethavebcencarricd.Suchinformationsarejustfundamentalsofdetectionandiden-hficationappliedbyactivesonars.Classificationandidentificationareimportantdevelopmentsofreccntsonarsin-c1udingthehomersoftorpedocs.Thisneedsadecpunderstandingrcferredtoechobe-haviors…     

Measurement of Eccentricity of the Centre of Mass from the Geometric Centre of a Sphere

The eccentricity of the centre of mass from the geometric centre of a spherical attracting mass in determining the Newtonian gravitational constant G is tested by means of an electronic balance. The experimental result shows that the eccentricity of the sample is about 0.31 μm with uncertainty of 0.05μm. Two density distribution models are discussed to estimate the uncertainty to G by the eccentricities of the attracting masses.     

Energy spectrum of α particles emitted from sources of different thicknesses

The shape of the energy distribution of all particles emitted by sources of different thicknesses was investigated. The energy distribution N(E) dE found can be expressed by a semi-empirical formula, which on the whole agrees with experiment. The source of particles was uranium oxide U ₃ 0 ₈.The energy distribution was measured with AGFA K2 nuclear emulsions 200 thick. Altogether 3,602 trajectories of particles in the nuclear emulsions of five plates were measured.The author would like to thank Prof. Dr. V. Petrílka, M. Rozko and L. Drka for remarks and their interest in this paper. He also thanks R. Krejí, J. Lejnarová and H. Koutová for carefully and promptly measuring the trajectories and for help in realizing the experiments.     

Time-of-flight studies of emission of μt from frozen hydrogen films

In recent TRIUMF experiments, a μ^- beam is stopped in a solid hydrogen film with a small fraction of T₂. The Ramsauer-Townsend (RT) mechanism allows μt to escape into vacuum with a few eV of energy. To study the emission process, an imaging system was used to determine the position of muon decays. Experimental histograms are in good agreement with a Monte Carlo simulation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Magnetic moment of ∑− from dispersion relations int

Magnetic moments of baryons are calculated from dispersion relations int, including the π \(\bar \pi \) -continuum. The largest deviation from the naiveSU(3)-expectation is found for∑ ^?, leading to μ₂₂₁₁=?1.80 nuclear magnetons instead of ?0.66.     

Weber potential from finite velocity of action?

The Weber potential energy U for charges q and q' separated by the distance R is U = (qq'/R)[1 – (dR/dt)²/2c²]. If this potential arises from a finite velocity c of energy transfer Q', where the retarded rate of transfer from q' to q is dQ(t-R/c)/dt = Q'[1 – (dR/dt)/c] and where the advanced rate from q to q' is dQ(t+R/c)/dt = Q'[1 + (dR/dt)/c], then the resultant time-average root-mean-square action is given by . Identifying Q' with the Coulomb potential energy qq'/R, the Weber potential is obtained. Using the same argument, Newtonian gravitation yields a corresponding Weber potential energy, qq'/R being replaced by ( - Gmm'/R).     

Scattering of O? from a graphite surface

Recently an extensive series of measurements has been presented for the angular distributions of oxygen molecules scattered from a graphite surface. Incident translational energies ranged from 291 to 614 meV with surface temperatures from 150 to 500 K. The measurements were taken with a fixed angle of 90° between the source beam and the detector and the angular distributions consisted of a single broad peak with the most probable intensity located at an angle slightly larger than the 45° specular position. Analysis with the hard cubes model for atom-surface scattering indicated that the scattering is primarily a single collision event with a surface having a collective effective mass much larger than a single carbon atom. Limited analysis with a classical diatomic molecular scattering theory was also presented. In this paper a more complete analysis using the classical diatomic molecular scattering theory is presented. The energy and temperature dependence of the observed angular distributions are well described as single collision events with a surface having an effective mass of 1.8 carbon graphite rings. In agreement with the earlier analysis and with other experiments, this suggests a large cooperative response of the carbon atoms in the outermost graphene layer.     

Calculations of Optical Rotation from Density Functional Theory

Density function theory calculations of frequency-dependent optical rotations [α]ω for three rigid chiral molecules are reported. Calculations have been carried out at the sodium D line frequency, using the ADZP basis set and a wide variety of functionals. Gauge-invariant atomic orbitals are used to guarantee origin-independent values of [ω]D. In addition, study of geometry dependence of [ω]D is reported. Using the geometries optimized at the B3LYP/ADZP level, the mean absolute deviation of B3LYP/ADZP and experimental laiD values yields 60.1°/（dm g/cm^3）. According to our knowledge, this value has not been achieved until now with any other model.     

Study ofγ radiation from100Pd decay

This paper presents a study of the rays from the electron capture decay of 3.63d ¹⁰⁰Pd. Singles and coincidence measurements provided an accurate determination of-ray intensities and an improved knowledge of the¹⁰⁰Rh level scheme. Experimental evidence supports excitation of levels in¹⁰⁰Rh at 86-, 136- and 154 keV, not previously reported from the decay of¹⁰⁰Pd.On leave from Departamento de Fisica, Comision Nacional de Energia Atomica, Buenos Aires, Argentina     

Cooperative emission from an ensemble of three-level Λ radiators in a cavity: An insight from the viewpoint of dynamics of nonlinear systems

Cooperative radiation emitted by an ensemble of three-level optical systems with a doublet in the ground state (Λ scheme), which is placed into a cyclic cavity, is studied theoretically. In contrast to the two-level model of emitters, this process with such a configuration of operating transitions may occur without population inversion in the whole, if the doublet is prepared at the initial instant in a superposition (coherent) state. In the ideal case of a Hamilton system, in which the cavity losses and relaxation in the radiator ensemble are disregarded, the conservation laws are derived, which allow a substantial reduction of the dimension of the phase space of the model (?¹¹ → ?⁵) and the application of methods of dynamics of nonlinear systems for analyzing the three-level superradiance under these conditions. The possibility of different (both quasiperiodic and chaotic) scenarios of the three-level superradiance is demonstrated on the basis of Poincaré’s mappings. Global bifurcation of the system upon a transition from the conventional superradiance regime to inversionless one is revealed. The effects of cavity losses, as well as homogeneous and inhomogeneous broadening in the system of radiators on the regularities found are also discussed.     

Estimation of Excited State Dipolemoments from Solvatochromic Shifts–Effect of pH

Multicomponent, highly efficient, catalytic synthesis of some polysubstituted imidazole under solvent-free condition is reported. Characterization of polysubstituted imidazole have been carried out by X-ray diffraction (XRD) and spectral techniques. Electronic spectral studies reveal that their solvatochromic behavior depends not only on the polarity of the medium but also on the hydrogen bonding properties of the solvents. Specific hydrogen bonding interaction in polar solvents modulated the order of the two close lying lowest singlet states. The solvent effect on both the absorption and emission spectral results have been analyzed by multiple parametric regression analysis. Solvatochromic effects on the emission spectral position indicate the charge transfer (CT) character of the emitting singlet states both in a polar and a non polar environment. The fluorescence decays for the imidazole fit satisfactorily to a single exponential kinetics. The prototropic studies of N,N-dimethyl-4-(1,4,5-triphenyl-1H-imidazol-2-yl)naphthalen-1-amine (DTINA) reveal that two monocations [imidazole nitrogen protanated (MC1) and dimethylamino nitrogen protanated (MC2)] and a dication [both imidazole nitrogen and dimethylamino nitrogen protanated (DC)] are formed by protonation in both ground and excited states. These observations are in consistent with quantum chemical calculations.     

Study of transversity GPDs from pseudoscalar mesons production at EIC of China

The exclusive η and π⁰ electroproduction is studied in the handbag approach based on the generalized parton distributions(GPDs) factorization. Predictions of π⁰ and η mesons are calculated for future electron-ion collider in China(EicC) energy ranges, using obtained cross sections we extract information on the transversity GPDs contributions to these processes.     

Determination of Quasi Fermi-Level Separation of Semiconductor Lasers from Amplified Spontaneous Emission

For characterization of semiconductor lasers, quasi-Fermi-level separation is a critical parameter due to its relationship with carrier density and gain. We suggest a new technique to determine the quasi-Fermi-level separation from amplified spontaneous emission measured from one facet.     

Derivation of the Euler Equations¶from a Caricature of Coulomb Interaction

A caricature of collisionless plasma involving 2N particles of opposite charge is introduced. The N first particles are called "ions" and don't move. The N other particles are called "electrons". At each time, there is a one-to-one matching between electrons and ions and each pair is linked by a "spring" so that each electron oscillates with fixed frequency )^у. The essential point is that the matching between electrons and ions is updated at every discrete time n‰, n˸,1,2,..., so that the total potential energy of the system stays minimal. This leads to a non trivial interaction which turns out to be a caricature of Coulomb interaction. It is proven that, provided the N ions are equally spaced in a bounded domain D and ), ‰ and N^у tend to zero at appropriate rates, the electrons behave as the fluid parcels of an incompressible inviscid liquid moving inside D according to the Euler equations. Our proof relies on a result of P. Lax on the approximation of volume-preserving transformations by permutations.     

Characteristics of scattering of Λ hyperons from nuclei within the potential model

The characteristics of bound states of hypernuclei were calculated in [1] in a wide range of mass numbers within the potential model for three different potentials. In this study, the phase shifts and low-energy parameters for scattering of Λ hyperons from core nuclei, considered in [1], have been calculated for the same potentials. The calculated scattering lengths and effective radii are compared with their values found in [1] on the basis of the data on the binding energies and vertex constants of hypernuclei.     

Elastic wave scattering from rough free surfaces of solids

Elastic wave scattering by a rough free surface of solids is analyzed. The analysis is based on the concept of scattering amplitude (SA) and perturbation approximation. The SA method is very convenient for rough surface scattering problems. By solving the boundary equations, the first and the second order solutions of approximate scattering amplitude are obtained. The general solutions are used for, as an example, the wave scattering by rough surfaces with Gaussian distribution. The mean field and variance are given. Finally, an experiment is designed to verifv the theoretical predications.     

Stochastic Inversion of Seabottom Scattering Coefficients from Shallow-Water Reverberation

A stochastic inverse method is presented to estimate the seabottom scattering coeffcients on the base of shallow-water ray mode reverberation theory. The reverberation data measured in the Asian Sea International Acoustic Experiment (ASIAEX) in the East China Sea in 2001 are analysed. The seabottom scattering coefficients areestimated from the reverberation loss. The inverted results are then tested by comparing the experiment data with the predictions of the reverberation vertical correlation and the reverberation loss measured on the different sea states at the same site. The fact that the experimental data are in good agreement with the theoretical predictions indicates the validity of the estimates.