Table of contents

Successive generations in the nucleon-meson cascade are calculated by means of generating functions. Expected muon spectra at different zenith angles and levels are in excellent agreement with measurements in the 0.2-50 GeV/c momentum range. A functional relation between the absolute value and slope of the primary spectrum and the inelasticity is established. On the average 1.6 intranuclear collisions in an air nucleus are taken into account. The calculated electron and positron content in an unshielded inclined muon telescope is 30%, with 100% detector efficiency. Coupling functions taking into account up to seven generations in the cascade, allowing for the primary composition are calculated. Expected time variations from anisotropies of different angular distributions in inclined meson telescopes at a high latitude station are given. Time characteristics such as expected times of maxima, phase differences and amplitude ratios for the north and south directed telescopes at Kiruna are computed for a variational spectrum of the form P^β cos Λ, where Λ is the angle between the asymptotic direction and the axis of the anisotropy. The reduction in amplitude due to three dimensional cascading is only 0.4_-0.4^+2.0%. A peculiar and persistent phase shift in the Kiruna north directed telescope is interpreted as being due to Forbush decreases and temperature effects. The yearly difference vector of the two telescopes over nearly one solar cycle has been analysed. Based on a variational spectrum with β = 0.0 and selected values of the free space amplitude, the phase and upper cut-off P_u of the anisotropy are derived. The variation of P_u with time shows a pronounced solar cycle dependence.

Cross sections of the reactions ¹⁷⁰Er(n, α)¹⁶⁷Dy, ¹⁷⁰Er(n, t)¹⁶⁸Ho, ¹⁷⁰Er(n, np/d)¹⁶⁹Ho, ¹⁷⁰Er(n, p)¹⁷⁰Ho and ¹⁶⁸Er(n, α)^165mDy as well as the (n, p) reaction cross sections of ^166-168Er isotopes and the (n, 2n) reaction cross sections of ^162-166Er isotopes have been measured at neutron energy 14.8 ± 0.7 MeV by using the activation method with Ge(Li) γ-ray detection. The experimental (n, 2n), (n, p) and (n, α) cross sections have been compared with the evaporation model or pre-equilibrium model predictions.

Density-dependent spectral lines play an important role in the plasma physics research. Such lines can be used for determination of plasma density from the ratio of spectral line intensities. In the preceding paper [1] we have considered the inelastic collisional transitions between close ion levels which are responsible for excited state distribution when it changes from coronal model at low electron densities up to Boltzman distribution at high electron densities. This variation is the reason of the density dependence of spectral line intensity ratios.

In this paper basing on the results obtained in [1] the ratios of several spectral lines of H, He and O-like ions are plotted as a function of electron density. The regions of the plasma parameters for which this ratio may be used as a diagnostics tool are found.

The results of this work makes it possible to diagnose plasmas (laser and electron beam plasma, exploding wires, plasma focus etc.) for electron densities 10¹⁸ < N_e < 10²³cm^-3.

A systematic study of the even configurations 5d^N 6s², 5d^N+1 6s and 5d^N+2 in neutral atoms of the platinum group has been performed by means of the parametric method. Consequently a number of empirical identifications of energy levels has been revised for Hf I, Ta I and Re I. In a generalized least squares fit 305 energy levels from Hf to Pt were interpreted by means of 59 parameters with a r.m.s. deviation of 122 cm^-1. An extrapolation towards lutecium has facilitated the theoretical interpretation of 8 low configurations in this element. The parametric study of 36 magnetic A hyperfine constants and 27 electric B constants has confirmed the labeling of the levels of Lu I.

On recordings made in the Physics Department of Lund University, we have identified 64, 65, 63 and 71 4p-4d transitions in Y VI, Zr VII, Nb VIII and Mo IX, respectively, establishing 23 levels of 4p³4d in each case. In Y VII, Zr VIII, Nb IX and Mo X we have identified 54, 53, 48 and 57 4p-4d transitions, establishing 19 levels of 4p²4d in each spectrum. The number of 4p-4d transitions identified in Y VIII, Zr IX, Nb X and Mo XI is 28, 27, 27 and 31; they establish all the 11 4p4d levels that can combine with the ground levels. In addition, two levels of 4s4p³ could be found from 4s-4p transitions.

The continued analysis of the spectrum of triply ionized iron, Fe IV, has led to a practically complete description of the three lowest electron configurations. Of 3d⁵ all 37 levels are established, of 3d⁴4s only one of the 63 levels is missing and of 3d⁴4p 177 of the 180 possible levels are found. The structure of the three configurations is analysed by least-squares fits to the observed levels and by Hartree-Fock calculations. The level values have been determined with an uncertainty of less than 0.4 cm^-1 from 706 lines of the transition group 3d⁵-3d⁴ 4p, extending over the region 446-789 Å, and 560 lines of the group 3d⁴4s-3d⁴4p in the region 1247-2028 Å. The results are based on spectrograms obtained by means of a low-voltage sliding-spark discharge and the two 10.7 m vacuum spectrographs at the National Bureau of Standards in Washington, DC

Predicted wavelengths and intensities of the forbidden transitions within 3d⁵ are collected in a list containing 95 entries from 1370 to 9393 Å. A comparison with Thackeray's line list for RR Telescopii shows an excellent agreement between prediction and observation as regards both wavelengths and intensities.

Two band systems of the emission spectrum of CuO in the green region have been rotationally analyzed, nameley the C²Π_i-X²Π_i and D²Δ_i-X²Π_i systems. Molecular constants of the states are given.

Two bands at 4432 Å and 4558 Å, recognized as the 0-0 and 0-1 transitions of a ⁴Σ_1/2-²Π_1/2 system in the emission spectrum of CuO, have been rotationally analyzed. The transition is designated k⁴Σ_1/2-X²Π_1/2. Molecular constants of the upper state are given.

An investigation is made of the blow-off characteristics of a two component laser produced plasma. Approximate similarity solutions describing the plasma expansion are given and it is shown that the inherent inhomogeneity of the problem limits the total growth of the associated two-stream instability.

Tonks-Dattner resonances in a plasma column were studied for neutral gas densities and frequencies ranging from about 10¹³ to 10¹⁵ cm^-3 and 3.9 to 4.4 GHz respectively. The dipole resonance appeared at electron densities predicted by cold plasma theory. A parabolic model for the electron density profile yielded consistent results over the entire neutral density range. Going from the lowest to the highest neutral gas densities the electron thermal energy varied from about 12 to 3 eV. The electro-acoustic standing waves occupied an increasingly larger distance between wall and profile as the electron thermal velocity increased.

We consider stimulated incoherent scattering from a semi-infinite unmagnetized plasma. Our results indicate that density discontinuities may have a significant effect on ionospheric backscattering experiments.

Nuclear spin lattice relaxation time T₁ of ¹⁹F have been studied in MSiF₆ · 6H₂O with M²⁺ = Fe²⁺, Co²⁺, Ni²⁺ and Cu²⁺ from 150 to 300 K The derived electron spin correlation times are mostly determined by rapid electron spin lattice relaxation and not by exchange spin flips. The electron spin lattice relaxation in CoSiF₆ · 6H₂O seems to follow an Orbach process with excited state at 625 cm^-1. Relaxation times T_1ρ in the rotating frame give information on molecular motion and on the structural phase transition in CoSiF₆ · 6H₂O.

The neutron scattering from normal (protonated p-PAA) and deuterated (d-PAA) para-azoxyanisole has been measured in the isotropic liquid phase at momentum transfers 0.8 A^-1 < Q < 5 A^-1 and energy transfers ℏω up to 25 mev. For p-PAA the spectra can be interpreted on a model of continuous, uniaxial rotational diffusion around the long molecular axis with diffusion coefficient D = 0.18 meV. For d-PAA, which is a coherent scatterer, the structure of the liquid manifests itself through the structure factor S(Q), which modulates the scattered intensity and introduces an energy narrowing (de Gennes narrowing) at the maxima of S(Q). Data on unoriented samples of d-PAA in the nematic phase are indistinguishable from those measured in the isotropic phase, suggesting that no collective excitations of the nematic phase do exist.