Multiple coulomb excitation of 167Er

The ground-state rotational band in ¹⁶⁷Er has been investigated through multiple Coulomb excitation with a 160 MeV ³⁵Cl beam. Excited states up to $\text{25}\text{2}{}^{\mathrm{+}}$ were established by measuring γγ coincidences and γ-ray angular distributions. Gamma-gamma angular correlations were also measured. Nuclear lifetimes of levels up to spin $\text{23}\text{2}$ have been determined from Doppler-broadened γ-ray lineshapes, and B(M1) and B(E2) values of intra-band transitions deduced. Considerable signature dependence was observed for level energies and M1 transition probabilities. A Coriolis band-mixing calculation was carried our for comparison with the experimental results. The measured M1 transition probabilities are compared to calculations based on a particle-rotor model, a cranking model, and a microscopic model with quantum-number projection.     

Influence of Coriolis anti pairing and alignment on the rotational states in nuclei

The inclusion of both Coriolos anti pairing (CAP) and alignment in the simple $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ model is studied. It is found that “backbending” occurs for too small angular frequencies in such a model.     

Anomalous electron thermal conductivity across the destroyed magnetic surfaces

New “Semicollisional” regime of the anomalous electron transport pertaining to the weakly collisional plasma is described in the paper. The transition from the collisionless to semicollisional case is determined by the ratio of the phase stochastization length of the parallel electron motion to the mean free path. It was shown also that the anomalous thermal conductivity can be described by the known “selfsimilar” expression $\text{χ}{}_{\mathrm{?}}\text{= χ}{}_{6e}\text{Ь}{}^2{}_0$ only for very strong collisions or high level of magnetic field turbulence.     

From high energy supersymmetry breaking to low energy physics through decoupling

We reconsider a realistic model of electroweak and strong interactions with calculable mass spectrum at the tree level in which supersymmetry and an extra gauge group factor ?(1) beyond SU(3) × SU(2) × U(1) are both broken at very high energies: $\text{M}{}_{\mathrm{<mtext>SUSY</mtext>}}\text{?(M}{}_{\mathrm{<mtext>W</mtext>}}\text{M)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, $\text{M}{}_{\mathrm{<mtext>U</mtext><mtext>?</mtext><mtext>(1)</mtext>}}\text{?M}\text{with}\text{M?M}{}_{\mathrm{<mtext>W</mtext>}}$. In spite of these high-energy scales, especially the large scale of supersymmetry breaking, the low energy spectrum - including the relevant Higgs boson - is decoupled from the heavy degrees of freedom. Due to the “non-renormalization” theorems this decoupling persists to all orders in perturbation theory.     

Functional derivative δTcδα2F(ω) for weak-coupling superconductors with paramagnetic impurities

We have calculated analytically the functional derivative $\text{δT}{}_{\mathrm{c}}\text{δα}{}^2\text{F(ω)}$ for weak-coupling superconductors with paramagnetic impurities using a simple “square-well model” for the electron-phonon interaction. The formulas obtained are sufficiently simple that we can obtain results as close to the critical concentration as we wish. It is found that the position of the maximum of the functional derivative continues to shift towards small frequencies with increasing concentration and that the height at maximum increases indefinitely.     

Microwave spectrum and hydrogen bonding in 1-aziridineethanol

From its microwave spectrum, 1-aziridineethanol,

$\text{CH}{}_2\text{CH}{}_2\text{NCH}{}_2\text{CH}{}_2\text{OH}$

is found to have a gauche OCCN configuration, maintained by an OH?N-type hydrogen bond. The normal species rotational constants (MHz), A = 8528.87(25), B = 2069.74(2), and C = 2020.41(2), are consistent with a small (～6°) distortion from the “staggered” configuration about the central CN bond. Assuming a “normal” hydroxyl group, the hydroxy d₁ data suggest a decrease in the O?N distance upon bridge deuteration of ～0.003 Å. The dipole moment is 2.77(5) D, with 2.34(3), 1.45(6), and 0.3(3) D “a,” “b,” and “c” components, respectively.     

Further studies of the electronic and vibrational spectra of ND2: Improved molecular parameters for the 000 and 010 levels of the ground state

Improved molecular parameters for the 000 and 010 levels of the $\text{X}\text{?}{}^2\text{B}{}_1$ ground state of ND₂ have been obtained by a weighted least-squares treatment using published microwave-optical double resonance frequencies, laser magnetic resonance data, infrared-optical double resonance frequencies, and extensive new optical data for the $\text{A}\text{?}{}^2\text{A}{}_1\text{-}\text{X}\text{?}{}^2\text{B}{}_1$ absorption spectrum. Revised assignments are given for 13 LMR transitions, including 4 “hot” band transitions.     

The (p, 2p) reaction on 6Li

The differential cross section for the quasi-elastic scattering of protons on ⁶Li is derived in the impulse approximation. The nucleus ⁵He is not treated as a bound nucleus in the derivation. Instead, the n-α interactions $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, $\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$, $\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ in the final state are included. Fits to the unknown vertex functions appearing in the expression obtained for the momentum distribution at the “ground state” of ⁵He are given, showing that the n-α $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ interaction is important at the “ground state” of ⁵He. The consistency between the observed momentum distribution and the ⁶Li form factor at low momentum transfers is shown utilizing Elton's model.     

Reorientational motion of the OH− ion in cubic sodium hydroxide

The rotational motion of the OH^? ion was studied in cubic NaOH at 575 K with quasielastic incoherent neutron scattering. The data are compared to two simple models yielding values for the radius of rotation R, the translational mean square displacement 〈u²〉_H, the rotational jump rate τ^?1 and the rotational diffusion coefficient D_R. The following parameter values are obtained: (a) rotational jump model: $\text{R = 0.95}\text{A}\text{?}$, $\text{〈u}{}^2\text{〉}{}_{\mathrm{H}}\text{= 0.052}\text{A}\text{?}{}^2\text{, τ}{}^{\mathrm{?1}}\text{= 2}\text{meV}$, (b) rotational diffusion model: $\text{R = 0.99}\text{A}\text{?}\text{, 〈u}{}^2\text{〉}{}_{\mathrm{H}}\text{= 0.046}\text{A}\text{?}{}^2\text{, D}{}_{\mathrm{R}}\text{= 0.72}\text{meV}$.     

An anomalous M1 transition in 38Cl

The observed enchangement of the M1 transition in ³⁸Cl between the 3^? state of the “$\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{-}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ multiplet” and the 4^? state of the “ mumultiplet” is explained.     

Lattice formulation of the CPn−1 non-linear σ models

We set up a general lattice version of non-linear σ models defined on homogeneous spaces. We then apply this to the CP^n?1 models which are the correct extension of the SU(2) σ model to SU(N). We exhibit their “confinement” property: the elementary multiplets Z_α used to describe the system do not appear as physical particles but only as bound states $\text{Z}{}_{\mathrm{\alpha }}\text{λ}{}_{\mathrm{\alpha \beta }}{}^{\mathrm{a}}\text{Z}{}_{\mathrm{\beta }}$. The method enable us to examine the “θ vacua” in the strong coupling limit by using a “dilute loop” approximation. We discuss the effect of the low activation energy for instantons which means that on a lattice, topological number is not conserved.     

Monte Carlo simulation of a three-dimensional spin glass

Similarly to two dimensions, the Edwards-Anderson model of (Ising) spins with a Gaussian nearest-neighbor exchange-force distribution gives near $\text{T}{}_{\mathrm{<mtext>c</mtext>}}\text{≈1.5}\text{ΔJ}\text{k}{}_{\mathrm{<mtext>B</mtext>}}$ a cusp in the susceptibility, a peak in the specific heat, and a continuous vanishing of the “order parameter”.     

Activation energy of field emission flicker noise power due to adsorbed potassium on tungsten

The temperature dependence of the field emission flicker noise spectral density functions has been investigated for potassium adsorbed on tungsten (112) planes by a probe hole technique. By integration of the spectral density functions $\text{W(?) = B}{}_{\mathrm{i}}\text{?}{}^{\mathrm{?ge}}\text{i}$ the noise power $\text{(δn}{}^2{}_{\mathrm{\Delta ?}}$ for different frequency intervals Δ? is obtained. From the exponential temperature dependence of $\text{(δn}{}^2{}_{\mathrm{\Delta ?}}$ noise power “activation energies” q_Δ? are determined. Plots of these energies versus coverage show a similar “oscillating” behaviour as recently found for $\text{W(?}{}_{\mathrm{j}}\text{)}$ or which indicates phase transitions of the adsorbed potassium submonolayers. The noise activation energies are discussed in terms of existing models and a comparison is made between the experimental q values and surface diffusion energies E_d as determined by conventional methods.     

Some aspects of the quark parton model

A modified Kuti-Weisskopf model which satisfies the Feynman threshold constraints is considered further. Detailed predictions for the sum of neutrino and anti-neutrino differential cross sections on nucleon (which can be readily compared with forthcoming NAL data), the shapes of the structure functions $\text{?}{}_2{}^{\mathrm{\nu p,\nu n}}$ and the ratio $\text{?}{}_2{}^{\mathrm{\nu p}}\text{/?}{}_2{}^{\mathrm{\nu n}}$, and spin-dependence of inelastic electron-nucleon scattering versus scaling variable x are delineated. We also compare in some detail the general features of our model with the “model independent” approach of Feynman for quark parton theory.     

Spin dynamics in the quasi-1 dimensional spin-glass FeMgBo4

The results of an inelastic neutron scattering investigation performed on the insulating title compound are presented. The spin dynamic is well described by a relaxation model leading to a quasi-elastic Lorentzian neutron-scattering line. The relaxation rate $\text{1}\text{τ}{}_{\mathrm{R}}$ is a linear temperature function for T>20 K, which is ascribed to the isotropic and 1-D character of the spin correlations. At T = 20 ? 5 K a drastic drop in $\text{1}\text{τ}{}_{\mathrm{R}}$ is observed reflecting a “crossover” to a highly frustrated 3D-spin glass state.     

Determination of fraction of molecules excited by laser IR radiation

To explain the observed excitation by laser IR radiation of moderate intensity (I = 1?10 MW/cm²) of the many rotational states (much greater than $\text{Ed}{}_{\mathrm{<mtext>01</mtext>}}\text{2}\text{hcB}$) it is suggested that mixing of the ground state components of the common symmetry type (“N-mixing”) take place. Estimation of the fraction of molecules excited by multiphoton processes is in satisfactory agreement with an experiment.     

Functional derivative δTc/δα2 (Ω)F(Ω) for weak coupling superconductors

We present approximate analytic calculation of the functional derivative $\text{δT}{}_{\mathrm{c}}\text{δα}{}^2\text{(Ω)F(Ω)}$, where T_c is the superconducting critical temperature and $\text{α}{}^2\text{(Ω)F(Ω)}$ is the electron-phonon spectral function, within the “square-well model” for the phonon mediated electron-electron interaction and weak coupling limit $\text{ω}{}_{\mathrm{D}}\text{(2πT}{}_{\mathrm{c}}\text{)? 1 (ω}{}_{\mathrm{D}}$ is the Debye energy). It is found that $\text{δT}{}_{\mathrm{c}}\text{δα}{}^2\text{(Ω)F(Ω) = (1 + λ)}{}^{-1}\text{G(Ω)}$ where λ is the familiar electron-phonon coupling parameter and $\text{G(Ω)}$ is a universal function of the reduced frequency $\text{Ω}\text{=}\text{Ω}\text{T}{}_{\mathrm{c}}$. We compare this formula with accurate numerical results for several weak coupling superconductors. The overall agreement is good     

Vibration-rotation-inversion Hamiltonian of formaldehyde

An expression for the Hamiltonian of a vibrating-rotating-inverting formaldehyde molecule is derived. In this derivation, we have used one curvilinear coordinate corresponding to the angle between the CO bond and the bisector of the angle H?H, and five rectilinear coordinates (linearized valence coordinates). Making use of the zeroth-order Hamiltonian, we have fitted to least-squares (i) the three observed $\text{Δ}\text{G(v}{}_4\text{+}\text{1}\text{2}\text{)}$ values for inversion of H₂CO and (ii) five of D₂CO, both belonging to the $\text{A}\text{?}{}^1\text{A}{}_2$ excited electronic states, in two separate calculations. For this, we have employed two model potential functions: one consisting of a sum of quadratic and Gaussian and the other a sum of quadratic and Lorentzian terms. In each case, the refined parameters, when transferred to the isotopic molecules (D₂CO and HDCO in the one case; H₂CO and HDCO in the other), could not account for their observed $\text{Δ}\text{G(v}{}_4\text{+}\text{1}\text{2}\text{)}$ values to the expected degree. We attribute the discrepancies to the inadequacy of the model chosen for the formaldehyde molecule which takes into account only one large amplitude bending motion and which neglects vibration-inversion interactions.We have also obtained a number of quadratic squared sum relations among the Coriolis coupling constants $\text{ζ}{}_{\mathrm{kl}}{}^{\mathrm{\alpha }}$ and the inertial constants $\text{a}{}_{\mathrm{k}}{}^{\mathrm{\alpha \beta }}$. These are applicable to any molecule undergoing a large amplitude bending motion provided the reference configuration is chosen as described in the text.