Absolute integrated intensity and individual line parameters for the 6·2μ band of NO2

The absolute integrated intensity of the 6·2μ band of NO₂ at 40°C was determined from quantitative spectra at ~ 10 cm^?1 resolution by the spectral band model technique. A value of 1430±300 cm^?2 atm^?1 was obtained. Individual line parameters, positions, intensities and ground state energies were derived, and line-by-line calculations were compared with the band model results and with the quantitative spectra obtained at ~ 0·5 cm^?1 resolution.     

E2 transition probabilities in the decoupled band of the 129La nucleus

Lifetimes of the yrast levels with spins I ^π = 23/2^? to 39/2^? in ¹²⁹La produced via the ¹²⁰Sn(¹⁴N, 5n) reaction at a beam energy of 77MeV have been measured by the Doppler shift attenuation method. The properties of the studied levels belonging to the πh_11/2 band were compared with the theoretical predictions obtained in the framework of the core quasi-particle coupling model. It is suggested that the rigid-rotor model used to describe the cores is too simplified as the even-even nuclei from the A ～ 130 region are susceptible to shape deformation. Reasonable agreement was obtained with the phenomenological cores based on the experimental data of ¹²⁸Ba.     

The equilibrium and preequilibrium neutron-emission spectra of some structural fusion materials for (<Emphasis Type="Italic">n</Emphasis>, <Emphasis Type="Italic">xn</Emphasis>) reactions up to 16 MeV energy

In this study, neutron-emission spectra produced by (n, xn) reactions for some structural fusion materials as ²⁷Al, ⁵¹V, ⁵²Cr, ⁵⁵Mn, and ⁵⁶Fe have been investigated by a neutron beam up to 16 MeV. Multiple preequilibrium mean-free-path constant from internal transition and the preequilibrium and equilibrium level-density parameters have been investigated for some (n, xn) neutron-emission spectra calculated in this study. Preequilibrium neutron-emission spectra were calculated by using new-evaluated hybrid model and geometry-dependent hybrid model, full-exciton model, and cascade-exciton model. The reaction equilibrium component was calculated by Weisskopf-Ewing model. The obtained results have been discussed and compared with the available experimental data and found agreement with each other. The text was submitted by the authors in English.     

Stochastic model of tilting mode in nuclear fission

A model of induced nuclear fission was developed with consideration of thermodynamically fluctuating orientation degree of freedom (tilting) of deformed nuclei. This model was applied to analysis of the experimental angular anisotropy of fission fragments in the ¹⁶O + ²³²Th, ²³⁸U, ²⁴⁸Cm, ²⁰⁸Pb, ²⁰⁹Bi; ¹²C + ²³⁶U; ¹⁹F + ²⁰⁸Pb; and ¹¹B + ²³⁷Np reactions. Information on the equilibrating time of the tilting mode was obtained. The text was submitted by the authors in English.     

S-matrix approach for description of refraction and absorption effects in9Be elastic scattering

A newS-matrix model was employed for analysing cross sections of⁹Be elastic scattering by¹²C,¹⁶O,²⁶Mg,²⁷Al,⁴⁰Ca,⁶⁰Ni and¹⁹⁷Au nuclei at 158 MeV. The results obtained are compared with those of optical model.     

Alpha-nucleus elastic scattering at intermediate energies

Elastic scattering of 288,340,480 and 699 MeV Alpha-particles was measured on ²⁰⁸Pb, ¹¹⁶Sn and ⁵⁸Ni. The data were analysed in terms of a phenomenological optical model. The optical potentials obtained were found to vary consistently with the target nucleus and the incident energy. The radial zone where the potentials are well determined was studied in detail. The data for ²⁰⁸Pb were also analysed with a folding model. The energy dependence of the strong-absorption radius and of the reaction cross section shows that the nuclear surface becomes slightly transparent for incident energies above 150 MeV per nucleon.     

Consistent description of collective level structure and neutron interaction data for 12C in the framework of the soft-rotator model

We have measured the neutron elastic and inelastic scattering angular distributions of ¹²C at 28.2 MeV. This data, together with information from other works, was used to construct a neutron scattering data-base in the energy region from 20 to 40 MeV. Then, a systematic analysis of nuclear structure and neutron interaction data for ¹²C was carried out in the framework of the soft-rotator model. The model was firstly applied to analyse the low-lying collective level structure of the ¹²C nucleus successfully. The intrinsic wave function obtained in such an analysis was then used to construct the coupling potentials in the coupled-channels formalism to calculate the neutron total and scattering cross sections. The quadrupole deformation parameter obtained in the present analysis was 0.164, which was much smaller in the absolute sense than the value used in the rotation-vibration model employed frequently in the past, i.e. ≈0.6. When averaged over the β-vibration function, however, the present result yields an effective quadrupole strength of about the same scale as the previous studies due to softness of the ¹²C wave function with respect to β₂ degree of freedom. The soft-rotator model was found to be very successful in reproducing both the structure and neutron scattering data consistently for the first time in this mass region.     

Comparison of proton and neutron spectra: The extended Griffin model,pairing and isospin

The energy spectra of protons and neutrons emitted in proton induced reactions on the targets¹⁰³Rh,¹⁵⁹Tb, and¹⁶⁹Tm were measured at a bombarding energy of 18 MeV and at a variety of emission angles. Angle-integrated emission spectra were calculated and compared with preequilibrium model predictions. The general validity of the extended Griffin model with a systematic empirical set of model parameter values was verified. Evidence was obtained for the conservation (partial or complete) of isospin as a quantum number and for the possible utility of including a pairing energy shift in the calculations.     

Angular distributions of photoneutrons from the 207, 208Pb(γ, n0) reactions

Angular distributions of photoneutrons from the ^{207, 208}Pb(γ, n₀) reactions were measured at 11 angles around θ = 90°. The γ-source, E_γ = 7–11.4 MeV, contained discrete lines (ΔE ? 30 eV) obtained from n-capture and was used in conjunction with a high-resolution ³He spectrometer. Strong evidence for an E2 contribution and for E2-E1 and possibly E1-M1 interference was obtained in both ²⁰⁷Pb and ²⁰⁸Pb. The results are compared with calculations using a direct-semidirect model which involved an E1 and isoscalar E2 giant resonances. The results indicate that this model could explain only certain features of the data while most of the other features remain unexplained.     

The kinetics of the R- and UV-band photoconductivity (PC) in radiation damaged diamond

Illumination in the UV-band of radiation damaged diamond was found to enhance the PC in the red (the RPC). Continuous R-illumination then caused the RPC to decay hyperbolically to zero. R-band illumination also enhanced the PC in the UV band (UPC). Continuous illumination in the UV-band then caused the UPC to decay to a level about half of the maximum UPC. A two-level model was proposed in which exchange of holes between the U- and R-levels via the valence band was assumed to take place under illumination. The differential equations obtained from the kinetics of the transitions were solved with some approximations, and were found to give an excellent agreement with the experimental results. Further support for the model was obtained from numerical integration of the differential equations. When compared with the experimental results this provided information on the crystal parameters involved. The transition rates for valence-band holes into the levels R and U were found to be: A_R= U_U = 2.3 × 10^?11m³sec^?1, which gave for the capture-cross-sections at 290 K of these centres S = 3.2 × 10^?17m². Surprisingly low densities of the order of 10¹²m^?3 were obtained for R and U, indicating that only a small fraction of the damage-produced defects play a role in the UPC and RPC.     

Dispersive semimicroscopic analysis of nuclear-nuclear collisions on the basis of a corrected folding-model potential

A procedure for correcting the energy dependence determined for the mean-field component of the optical potential on the basis of the double-folding model with allowance for exchange effects in the approximation of single-nucleon exchange knockout is used to calculate the mean field and to analyze data on elastic scattering within the dispersive semimicroscopic optical-potential model. The results of an analysis of all data (including those that were obtained quite recently) on ¹⁶O + ¹²C and ¹⁶O + ¹⁴C interactions at energies of up to 100 MeV per nucleon are presented. The energy dependence of the resulting potentials agrees well with that which was obtained previously within the phenomenological approach. A systematics of the positions of Airy minima in angular distributions versus the reduced mass in the range from 2 to 8 amu is constructed.     

Dynamic model of mass-angular correlations of quasi-fission fragments

A dynamic model of the mass-angular correlations of quasi-fission fragments was developed. The projection of the angular momentum onto the symmetry axis of the dinuclear system and its rotation angle are treated as dynamic variables in the model. The model was tested in the analysis of the experimental data for the ⁶⁴Ni + ¹⁹⁸Au reaction at E _lab = 383 and 418 MeV. Information on lifetimes of the dinuclear system was obtained.     

The lifetime of the 3907 keV state of 19F

The mean lifetime of the 3907 keV state of ¹⁹F has been measured by the Doppler shift attenuation method (DSAM). The value obtained was 9 ± 5 fs. Transition strengths derived from this lifetime and previously measured branching ratios are compared with the results obtained from shell model calculations. The importance of including particle-hole configurations is discussed and it is shown for example that the energy and lifetime of the state are consistent with a predominantly p^?2 sd⁵ structure.     

Developments in geothermal energy in Mexico—Part thirty-three. Simultaneous determination of the thermal properties of geothermal drill cores

Thermal conductivity, thermal diffusivity and specific heat capacity of five drill cores from the Los Humeros and La Primavera geothermal fields were obtained via parameter estimation. The data were obtained by fitting an analytical model to the transient temperature rise caused by a line source of heat of constant strength located along the axis of the samples. The model was obtained from the solution to the problem of an infinite region bounded internally by a hollow circular cylinder with thermal contact resistance at the cylinder surface (J. H. Blackwell, Transient heat flow problems in cylindrical geometry, Ph.D. Thesis, University of Western Ontario Canada, London, Canada, 1952). Results were obtained for fused quartz and a Berea sandstone for calibration purposes and the agreement with known properties for these samples showed maximum differences of 10%. Results obtained for a dry drill core from the Los Humeros field showed a thermal conductivity of 1.36 W m⁻¹ K⁻¹, a diffusivity of 0.54 × 10⁶ m² s⁻¹ and a specific heat capacity of 0.96 kJ kg⁻¹ K⁻¹. Results for dry drill cores from the La Primavera geothermal field showed thermal conductivities between 1.53 and 2.51 W m⁻¹ K⁻¹ while thermal diffusivity varied from 0.71 to 1.0 × 10⁻⁶ m² s⁻¹. Specific heat capacity varied from 0.73 to 1.03 kJ kg⁻¹ K⁻¹. Results obtained for these cores under water saturation conditions showed significant increases in all three properties with the degree of increase being a function of the pore volume occupied by the water.     

Thermal Cross‐Linking of Poly(Vinyl Methyl Ether). III. Rheological Kinetics of Cross‐Linking Reaction

Abstract

The kinetics of the thermally activated cross‐linking reaction of poly(vinyl methyl ether) (PVME) were investigated rheologically by evaluating the viscoelastic material functions such as elastic storage modulus, G′, viscous loss modulus, G″ and complex dynamic viscosity, η*, during the curing process, both isothermally and nonisothermally. The isothermal kinetics reaction was described using a phenomenological equation based on the Malkin and Kulichikhin model, which was predicated originally for the isothermal curing kinetics of thermosetting polymers followed by differential scanning calorimetery (DSC) and was found to be applicable for rheokinetic reactions as well. An excellent representation of the data was obtained using this model; the rate of the reaction was found to be second order regardless of the temperature, which is in good agreement with literature data. The temperature dependence of the cross‐linking rate constant was described by an Arrhenius plot with an apparent activation energy equal to 60–62 kJ mol^?1, in reasonable agreement with the value obtained previously from the temperature dependence of gel time, t _gel. The nonisothermal kinetics reaction rate was described by a model that included the classical rate equation, the Arrhenius equation, and the time–temperature relationships. The apparent activation energy obtained nonisothermally was found to be frequency independent and equal to 72 kJ mol^?1, in very good agreement with the value obtained isothermally from the temperature dependence of t _gel in part II.     

Production of π0ρ0 pair in electron-positron annihilation in the Nambu-Jona-Lasinio model

The process e ⁺ e ^? ?? ??⁰??⁰ is described in the framework of the expanded NJL model in the energy region from 0.9 to 1.5 GeV. The contribution of intermediate state with vector mesons ??(782), ??(1020), and ???(1420), where ??? is the first radial excitation of ?? meson, was taken into account. Results obtained are in satisfactory agreement with experimental data.     

Ultracold collisions in the system of three helium atoms

The Faddeev differential equations for a system of three particles with a hard-core interaction are described. Numerical results on the binding energies of the ⁴He₃ and ³He⁴He₂ trimers and on ultracold collisions of ^3,4He atoms with ⁴He₂ dimers obtained with the help of those differential equations are reviewed. The results obtained for the hard-core model using the Faddeev equations are compared with analogous results obtained by alternative methods.