Notizen: Desorientierung von optisch ausgerichteten Na-Atomen durch Stöße mit gesättigten Kohlenwasserstoffen/Disorientation of Optically Oriented Na-atoms in Collisions with Saturated Hydrocarbons

1973 ◽  
Vol 28 (5) ◽  
pp. 793-794 ◽  
Author(s):  
H. Soboll

Cross sections for collisionally induced disorientation of of the Na (3 2S½) sublevels have been measured for the C1 - C4 saturated hydrocarbons. The strong increase of the cross sections with the number of buffer gas electrons can be explained by using the model of spin-orbit-relaxation.

1979 ◽  
Vol 57 (4) ◽  
pp. 540-549 ◽  
Author(s):  
R. de Swiniarski ◽  
Dinh-Lien Pham ◽  
G. Bagieu ◽  
H. V. Geramb

Analyzing powers and cross sections have been measured for elastic and inelastic scattering of 40 MeV polarized protons from 90Zr and 92Zr. The analysis has been carried out in the DWBA within the framework of the macroscopic and microscopic models. Furthermore, the coupled-channels calculations using the vibrational model and the full Thomas form for the spin–orbit potential give a very good description for both the cross sections and the analyzing powers of the iow-lying2+, 3−, 5−, and 4+ states in 92Zr and the 2+ and 3− in 90Zr. The cross section and analyzing power for the first 2+ state in these nuclei were compared with previous results at 30 and 20.3 MeV, and from this comparison a certain energy dependence of the relative strength of the spin–orbit deformation to the central deformation could be observed. Microscopic model calculations with tensor and spin–orbit components included in the projectile–target real interaction and with an exact treatment of knock-on' exchange have been performed for the 2+ states in these nuclei. An attempt has also been made in order to include the imaginary component in the N–N interaction. For these calculations, rather good agreement was obtained especially for the 2+ state in 92Zr but poor agreement for 90Zr. Finally, valence plus core polarization calculations have also been done and showed a very good agreement between theory and experiment for those 2+ transitions.


1969 ◽  
Vol 24 (11) ◽  
pp. 1716-1720
Author(s):  
H. Schlumbohm

Charge exchange cross sections for the four systems He+, Ne+ + Ar, Kr have been measured, ap­plying slow ions gathering techniques. The values are several 1O-16 cm2 and are almost constant between 20 and 200 eV collision energy. The comparison with previously published data for charge exchange into optically excited higher states of the ions show that these reactions prefer at least at 25 to 30% endothermic channels instead of the exothermic one without excitation. - Additionally the cross section of the endothermic process Ar++Ne was measured. Above a threshold energy of 17 eV it shows a strong increase and a constant value of 7 · 10-17 cm2 between 20 and 200 eV.


1977 ◽  
Vol 55 (1) ◽  
pp. 43-54 ◽  
Author(s):  
R. de Swiniarski ◽  
Dinh-Lien Pham ◽  
G. Bagieu

Analyzing powers and cross sections have been measured for elastic and inelastic scattering of 30 MeV polarized protons from 90Zr, 92Zr, and 92Mo. The experimental results are analyzed in terms of the coupled-channels formalism using the vibrational model. The best fits for the analyzing power for all the nuclei are obtained by using the full Thomas form for the spin–orbit potential. These calculations give a very good description for both the cross sections and the analyzing powers of the low-lying 2+, 3−, 5−, and 4+ states in 90Zr, 92Zr, and 92Mo. Only a small increase of the spin–orbit deformation over the central deformation (βLS/βcentral = 1.5) is needed to reproduce the data; this is contrary to the situation at lower energy where a large increase of this ratio was required (Raynal). Some differences between the 90Zr–92Mo data (which are similar) and the 92Zr data have also been observed; this is, however, in agreement with previous results at lower energy. Microscopic model calculations with tensor and spin–orbit components included in the projectile–target interaction (real interaction), and with an exact treatment of 'knock-on' exchange, have also been performed for the 2+ states in these nuclei. These calculations give a very good agreement with the cross sections but a rather poor agreement with the analyzing powers even when a complex interaction is used.


1971 ◽  
Vol 32 (1) ◽  
pp. 7-9 ◽  
Author(s):  
J. Galin ◽  
D. Guerreau ◽  
M. Lefort ◽  
X. Tarrago

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.


1986 ◽  
Vol 6 (6) ◽  
pp. 391-402 ◽  
Author(s):  
Mark L. Campbell ◽  
Nick Furio ◽  
Paul J. Dagdigian

Chemiluminescence cross sections for reaction of the individual spin–orbit states of metastable Ca(PJ03) with CH3I, CH2I2, and SF6 have been determined by the use of optical pumping state selection. This technique was also used to separate the chemiluminescence arising from the two excited metastable Ca 3P0 and 1D states. The spin–orbit dependence of the chemiluminescence pathway was found to be substantial for the CH3I and CH2I2 reactions and similar to that previously observed for halogen diatom and alkyl bromide reagents. By contrast, no spin–orbit effect was observed for Ca(3P0)+SF6. These results are discussed in terms of our previously presented model for the origin of spin–orbit effects in chemical reactions.


2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Roman N. Lee ◽  
Alexey A. Lyubyakin ◽  
Vyacheslav A. Stotsky

Abstract Using modern multiloop calculation methods, we derive the analytical expressions for the total cross sections of the processes e−γ →$$ {e}^{-}X\overline{X} $$ e − X X ¯ with X = μ, γ or e at arbitrary energies. For the first two processes our results are expressed via classical polylogarithms. The cross section of e−γ → e−e−e+ is represented as a one-fold integral of complete elliptic integral K and logarithms. Using our results, we calculate the threshold and high-energy asymptotics and compare them with available results.


2021 ◽  
Vol 103 (19) ◽  
Author(s):  
Miguel J. Carballido ◽  
Christoph Kloeffel ◽  
Dominik M. Zumbühl ◽  
Daniel Loss

Author(s):  
Georges Griso ◽  
Larysa Khilkova ◽  
Julia Orlik ◽  
Olena Sivak

AbstractIn this paper, we study the asymptotic behavior of an $\varepsilon $ ε -periodic 3D stable structure made of beams of circular cross-section of radius $r$ r when the periodicity parameter $\varepsilon $ ε and the ratio ${r/\varepsilon }$ r / ε simultaneously tend to 0. The analysis is performed within the frame of linear elasticity theory and it is based on the known decomposition of the beam displacements into a beam centerline displacement, a small rotation of the cross-sections and a warping (the deformation of the cross-sections). This decomposition allows to obtain Korn type inequalities. We introduce two unfolding operators, one for the homogenization of the set of beam centerlines and another for the dimension reduction of the beams. The limit homogenized problem is still a linear elastic, second order PDE.


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