Calculation of the nuclear vertex constant (asymptotic normalization coefficient) for the virtual decay 6Li → α + d on the basis of the three-body model and application of the result in describing the astrophysical nuclear reaction d(α, γ)6Li at ultralow energies

Within the (α, n, p) three-body model, the s-wave ⁶Li → α + d vertex constant G ₀₁ and the asymptotic normalization coefficient C ₀₁ (these two quantities are proportional to each other) for the wave function describing the ⁶Li nucleus in the α + d channel are calculated by solving Faddeev equations for various sets of nucleon-nucleon and α N potentials. The resulting values of G ₀₁ and C ₀₁ are used to calculate the astrophysical factor S(E) for the radiative-capture reaction d(α, γ)⁶Li at energies in the range E = 0–600 keV. The calculated values of G ₀₁ and C ₀₁ appear to be sensitive to the form of the pair potentials used. It is shown that, upon correctly taking into account the contributions of the E2 and E1 multipolarities, the values of S(E) in the region E < 150 keV are determined primarily by the values of C ₀₁ and of the ⁶Li binding energy in the α + d channel.     

Light emission at the E1 and E1+Δ1 gaps in heavily doped p-type Ge and GaAs

We report the observation in heavily doped p-type germanium (N_h ≥ 10¹⁸cm^?3) of two weak light emission bands centered at the energies of the E₁ and E₁+Δ₁ interband gaps (2.22 and 2.42 eV at 80 K). These bands, which are 100% polarized, are found only for excitation with laser frequencies slightly above the gaps. We attribute them to photon scattering by inter-valence-band excitations of the holes associated with the heavy doping. The fact that the emission bands do not shift with the exciting laser frequency is assigned to a strong resonance enhancement of this scattering near the E₁ and E₁+Δ₁ gaps. We have also observed the corresponding light emission at the E₁ gap (3.0 eV) in p-type GaAs.     

Anomalous phonon intensities in the Raman spectrum of disordered CsMg1−xCoxCl3

The five Raman-active $\text{k}\text{= 0}$ phonons have been measured at low temperatures and for a range of x in the disordered lattice CsMg_1-xCo_xCl₃. While the E_2g^a, E_2g^b, E_2g^c and A_1g modes at 55.0, 132.0, 189.0 and 255.0 cm^?1 for x = 0 exhibit normal one-mode behaviour, the intensity of the E_1g phonon at 127.5 cm^?1 has a most unusual concentration dependence which requires a new theory.     

Analysis of average primary gamma-transition intensities and cross sections of the113Cd(n, γ) reaction

A combined analysis of the available data on the primaryγ-ray intensities from the¹¹³Cd(n, γ) reaction atE _n=1.9 and 24.3 keV neutron energies together with the data on¹¹³Cd neutron capture cross sections in theE _n=3–200 keV energy region was carried out. The neutron strength functions were determined asS _n0=(0.260±0.073) 10^?4 and S_n1=(5.06±0.67) 10^?4. No spin-orbit splitting of thep-wave neutron strength function was found. The energy dependence of theE 1 radiative strength function {ie147-01} was fitted by the Kadmenski-Furman model somewhat better than by a standard Lorentzian. TheM 1 giant resonance parameters were obtained as E _G ^{M 1} =8.8±1.6 MeV and Γ _G ^{M 1} = 4.7±2.6 MeV. The neutron capture cross section of¹¹³Cd from its isomeric state ({ie147-02}=11/2^?, E ₁ ^m =263.7 keV) was calculated.     

Excess molar volumes and viscosities for binary mixtures of alkoxypropanols with 1-alkanols at 298.15 K

The excess molar volumes (V_m^E) and viscosities (η) for binary mixtures of dipropylene glycol tert-butyl ether with methanol, 1-propanol, 1-pentanol, and 1-heptanol and viscosities of dipropylene glycol monomethyl ether and dipropylene glycol monobutyl ether with methanol, 1-pentanol, and 1-heptanol have been reported at 298.15 K. The V_m^E are negative for the mixtures investigated. Sign and magnitude of V_m^E and viscosity deviations were used to analyze the mixing behavior of the components.     

Realizations of the exceptional modular invariant A(1)1 partition functions

We show that the E₆ and E₈ modular invariant combinations of A⁽¹⁾₁ characters in the classification of Cappelli, Itzykson and Zuber can be realized as partition functions of k=1 conformally invariant WZW models on the group manifolds of Sp(4) and G₂, respectively. Together with the D₄ combination, which is known to be realized by the WZW model on SU(3), these are the only such cases where the SU(2) local symmetry extends to a larger one. The E₇ combination is briefly discussed.     

Energies of Cu1+ ions sputtered from Cu by very low energy (50 eV < E < 1 keV) Inert gas ions

He⁺, Ne⁺ and Ar⁺ ions with energies E₁ between 50 and 1000 eV were used to bombard a polycrystalline Cu target at an angle of 45°. The energies, E₂, of the Cu₁⁺ ions sputtered at 90° to the primary beam were investigated using a UHV magnetic sector mass spectrometer. The maxima of the energy distributions as measured by the instrument, were at values of E₂ of about 4 eV (±1 eV), nearly independent of e₁ and primary ion mass. Plots of log N(E₂) versus log E₂ displayed limited linear portions over which the functional dependence of N(E₂) is proportional to E₂^?0.5. Plots of the average secondary ion energy, ē₂, versus the energy transferred by the primary ion to a Cu atom in a direct collision $\text{([}\text{4m}{}_1\text{m}{}_2\text{(m}{}_1\text{+ m}{}_2\text{)}{}^2\text{]E}{}_1\text{)}$, indicate that ē₂ increases linearly with transfer energy up to a transferred energy of about 200 eV, independent of primary ion mass. Above about 200 eV transferred energy, ē₂ asymptotically approaches values which depend upon primary ion mass. At transferred energies below about 200 eV, the collision kinematics in the fust few collisions appears to dominate the emission process.     

Systematic study of the product((E(2_2~+)/E(2_1~+)) * B(E2)↑) through the asymmetric rotor model

A systematic study of the product((E(2_2~+)/E(2_1~+))*B(E2)↑) is carried out in the major shell space Z=50-82,N=82-126 within the framework of the asymmetric rotor model where the asymmetry parameter γ0reflects change in the nuclear structure.A systematic study of the product((E(2+)/E(2+))*B(E2)↑) with neutron number N is also discussed.The product((E(2_2~+)/E(2_1~+))*B(E2)↑) provides a direct correlation with the asymmetry parameter γ0.The effect of subshells is visible in Ba-Gd nuclei with N 82,but not in Hf-Pt nuclei with N 104.We study,for the first time,the dependency of the product((E(2_2~+)/E(2_1~+))*B(E2)↑) on the asymmetry parameterγ0.     

Oxygen vacancy model for the E1′ center in SiO2

An (oxygen)^- vacancy model of the E₁^≈ center in alpha quartz, featuring an asymmetric relaxation of the two silicons adjacent to the oxygen vacancy, is presented and analyzed. This model is shown to be consistent with both theoretical calculations and experimental hyperfine data, in contrast with any model previously proposed for the E₁^≈ center.     

T=1 states in26Al

The resonance reaction²⁵Mg(p, γ)²⁶Al in the energy rangeE _p =300–400 keV was used to populate high-lying bound states in the self-conjugate nucleus²⁶Al. The existence of three resonances atE _p =304, 316 and 388 keV was verified, the spins of the ones at 316 and 388 keV were found to be 3^? and 2⁺, respectively. The spin of the bound level at 4,547 keV level was fixed to beJ ^π=2⁺. Several strong isovector Ml transitions were observed, which led toT=1 assignments for the levels atE _x =4,191, 4,547, 4,599, 5,141 and 5,542 keV. The results for excitation energies and values ofJ ^π,T together with previous experimental and theoretical data on²⁶Al and the neighboring |T _z |=1 nuclei²⁶Mg and²⁶Si are discussed in the framework of the isospin model.     

Reestimation of the energy of extensive air showers at the Yakutsk EAS array with the CORSIKA package

The responses of ground and underground muon scintillation detectors of the Yakutsk extensive air shower (EAS) array from primary particles with the energy E ₀ ≥ 10¹⁷ eV have been calculated within the QGSJET-01-d, QGSJET-II-04, SIBILL, and EPOS-LHC models with the CORSIKA package. A new estimate obtained for E ₀ is lower by a factor of about 1.41 than that previously obtained within the calorimetric method for EASs.     

CO2 adsorption on Cr(1 1 0) and Cr2O3(0 0 0 1)/Cr(1 1 0)

We attempt to correlate qualitatively the surface structure with the chemical activity for a metal surface, Cr(1 1 0), and one of its surface oxides, Cr₂O₃(0 0 0 1)/Cr(1 1 0). The kinetics and dynamics of CO₂ adsorption have been studied by low energy electron diffraction (LEED), Aug er electron spectroscopy (AES), and thermal desorption spectroscopy (TDS), as well as adsorption probability measurements conducted for impact energies of E_i = 0.1-1.1 eV and adsorption temperatures of T_s = 92-135 K. The Cr(1 1 0) surface is characterized by a square shaped LEED pattern, contamination free Cr AES, and a single dominant TDS peak (binding energy E_d = 33.3 kJ/mol, first order pre-exponential 1 × 10¹³ s⁻¹). The oxide exhibits a hexagonal shaped LEED pattern, Cr AES with an additional O-line, and two TDS peaks (E_d = 39.5 and 30.5 kJ/mol). The initial adsorption probability, S₀, is independent of T_s for both systems and decreases exponentially from 0.69 to 0.22 for Cr(1 1 0) with increasing E_i, with S₀ smaller by ∼0.15 for the surface oxide. The coverage dependence of the adsorption probability, S(Θ), at low E_i is approx. independent of coverage (Kisliuk-shape) and increases initially at large E_i with coverage (adsorbate-assisted adsorption). CO₂ physisorbs on both systems and the adsorption is non-activated and precursor mediated. Monte Carlo simulations (MCS) have been used to parameterize the beam scattering data. The coverage dependence of E_d has been obtained by means of a Redhead analysis of the TDS curves.     

Metastable helium atom scattering from Ni(1 1 0) surface

The survival probability (SP) of metastable helium atoms (He¹) during scattering from the clean, alkalated and oxygen-adsorbed Ni(1 1 0) surfaces has been examined in the kinetic energy range of 50–400 meV. The measurements were carried out using a time-of-flight technique and a pulsed-discharge type metastable helium atom source. The SP is nearly constant for a kinetic energy (E_kin) of 50–100 meV and decreases exponentially with the increase in E_kin at 100–400 meV. It has been shown that the SP at E_kin=100–400 meV depends on the repulsive part of the He¹-surface interaction potential.     

Raman E 1 and E 1 + Δ1 resonances in a system of unstrained germanium quantum dots

The positions and shapes of the Raman E ₁ and E ₁ + Δ₁ resonances of optical phonons are studied as functions of the size of unstrained germanium quantum dots. The quantum dots are grown by molecular-beam epitaxy in GaAs/ZnSe/Ge/ZnSe structures on GaAs(111) wafers. The positions of the E ₁ and E ₁ + Δ₁ resonances are found to shift by at most 0.3 eV. This shift is shown to be well described in terms of a cylindrical model using the quantization of the spectrum of bulk electron-hole states in germanium that form an exciton in a two-dimensional critical point. The fact that the peaks of the E ₁ and E ₁ + Δ₁ resonances appear separately has been detected for the first time, and it is related to the transformation of the interband density of states into a delta function because of spectrum quantization. An increase in the resonance amplitudes in quantum dots as compared to the bulk case is related to the degeneracy multiplicity of the exciton state in the (111) direction.     

Half-life and configuration of the 1/2+ intruder state in203Bi

The decay properties of theJ ^π=1/2⁺,E _exc=1,098 keV state in²⁰³Bi were studied. The state was populated via the²⁰⁴Pb(p, 2n) reaction and the activity was studied with the ion guide isotope separator on-line system IGISOL. The half-life of the 1/2⁺ state was measured to beT _1/2=303 ±5 ms. From this value the partial half-lives of the three depopulating branches 1/2⁺ →7/2^? (E3), 1/2⁺→5/2^? (E3 +M2) and 1/2⁺→9/2 _g.s. ^? (M4) were deduced. Since all the transitions are configuration forbidden in first order, a detailed study of second-order shell-model configuration mixing could be performed.     

Spin-0 and spin-1/2 particles in a constant scalar-curvature background

We study the Klein-Gordon and Dirac equations in the presence of a background metric ds²=−dt²+dx²+e^−2gx(dy²+dz²) in a semi-infinite lab (x>0). This metric has a constant scalar-curvature R=6g² and is produced by a perfect fluid with equation of state p=−ρ/3. The eigenfunctions of spin-0 and spin-1/2 particles are obtained exactly, and the quantized energy eigenvalues are compared. It is shown that both of these particles must have nonzero transverse momentum in this background. We show that there is a minimum energy E²_min=m²c⁴+g²c²?² for bosons (E_KG>E_min), while the fermions have no specific ground state (E_Dirac>mc²).     

The ν1 and ν1 + ν2 − ν2 infrared absorption bands of H12CP

The vibration-rotation spectrum of HCP was recorded in the region of the ν₁ band with a resolution of about 0.035 cm^?1. All the data available were combined to calculate spectroscopic constants for the 00⁰0, 10⁰0, 01^1e0, 01^1f0, 11^1e0, and 11^1f0 states.     

Ligand-to-metal charge-transfer quenching of the Eu(D1) state in europium-doped tris(2,2,6,6-tetramethyl-3,5-heptanedionato)gadolinium (III)

Rate constants for the decay of the Eu³⁺(⁵D₁) state in dilute Eu³⁺-doped tris(2,2,6,6-tetramethyl-3,5-heptanedionato)gadolinium(III) are reported for a temperature range 50-315 K. A temperature-independent contribution of 1.3×10⁶ s⁻¹ is attributed to carbonyl mediated ⁵D₁→⁵D₀ relaxation. A temperature-dependent contribution, that has been parameterized as k_CT=Ae^−E_a/kT with E_a=2540±140 cm⁻¹ and A=1.3×10¹² s⁻¹ is attributed to quenching of ⁵D₁ by a low-lying ligand-to-metal charge-transfer state (CTS). The height of the activation barrier, E_a, relative to the previously reported height for charge-transfer quenching of the Eu³⁺(⁵D₀) state in the pure europium analog (J. Phys. Chem. 100 (1996) 9216) is discussed in terms of mechanistic implications. Specifically, these data strongly suggest that quenching of ⁵D₁ by the charge-transfer state is mediated by the ⁵D₀ state with a novel, indirect mechanism.     

High-resolution (e,e') study of isovector M1 and M2 transitions in the oxygen isotopes: (I). 16O

The M1 and M2 transition strength distribution for ¹⁶O in the excitation energy range from 16 to 20 MeV has been measured in a high-resolution electron scattering experiment. The M1 strength is concentrated in three sharp states at E_x = 16.22, 17.14 and 18.79 MeV (± 0.01 MeV) with B(M1, k)↑ = 0.20 ± 0.02, 0.32 ± 0.03 and 0.13 ± 0.03 μ_N², respectively. An additional strength of 0.35 ± 0.09 μ_N², distributed over eight weakly excited states with excitation energies E_x = 17.4 to 18.0 MeV, brings the total measured M1 strength to B(M1, k)↑ = 1.0 ± 0.1 μ_N². The experimental M2 strength is distributed over states at E_x = 16.82, 17.78, 18.50 and 19.0 MeV (± 0.01 MeV) with B(M2, k)↑ = 19 ± 2, 13 ± 2, 59 ± 7 and 341 ± 51 μ_N² · fm², respectively. Electric transitions were also measured to states at E_x = 16.45 MeV (2⁺, E2), 17.30 MeV (1⁺, E1) and 18.20 MeV (2⁺, E2). Calculations were performed using the modified surface delta interaction in a 2p-2h shell model for the M1 transitions and the random phase approximation for the M2 transitions. The results show the sensitivity of the M1 strength as a measure of ground-state correlations and compare well with results from the ¹⁵N($\text{p}$, γ) reaction.