Formal calculation of the pick-off annihilation rate for ortho- and parapositronium

1991 ◽  
Vol 43 (13) ◽  
pp. 10036-10041 ◽  
Author(s):  
A. Dupasquier ◽  
P. De Natale ◽  
A. Rolando
Keyword(s):  
Annihilation Rate ◽  
Formal Calculation

Addendum to "Hadronic corrections to the annihilation rate of heavy vector mesons to lepton pairs"

1980 ◽  
Vol 21 (7) ◽  
pp. 2034-2035 ◽  
Author(s):  
Enrico C. Poggio ◽  
Howard J. Schnitzer
Keyword(s):  
Annihilation Rate ◽  
Vector Mesons ◽  
Lepton Pairs

Comparative measurements of annihilation rate coefficients of fluorine radicals in a r.f. SF6 plasma by different time-resolved actinometry techniques

1999 ◽  
Vol 116-119 ◽  
pp. 1123-1126
Author(s):  
V. Shogun ◽  
A. Tyablikov ◽  
V. Pashkov ◽  
W. Scharff ◽  
T. Wallendorf ◽  
...  
Keyword(s):  
Rate Coefficients ◽  
Annihilation Rate ◽  
Time Resolved

Complex dependence of the positron annihilation rate on methane gas density and temperature

1975 ◽  
Vol 62 (5) ◽  
pp. 1777-1789 ◽  
Author(s):  
J. D. McNutt ◽  
V. B. Summerour ◽  
A. D. Ray ◽  
P. H. Huang ◽  
D. A. Johnson
Keyword(s):  
Positron Annihilation ◽  
Annihilation Rate ◽  
Gas Density ◽  
Methane Gas ◽  
Complex Dependence

Magnetic Field Effect on Electrochemiluminescence of Carbazole

1971 ◽  
Vol 49 (21) ◽  
pp. 3577-3578 ◽  
Author(s):  
K. S. V. Santhanam
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Emission Intensity ◽  
Applied Field ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
High Magnetic Fields ◽  
Annihilation Rate ◽  
Triplet Triplet Annihilation

Effect of magnetic field on electrochemiluminescence of carbazole has been studied in N,N dimethylformamide. The emission intensity increases with increasing applied field with a tendency to decrease at high magnetic fields. An explanation involving perturbation of triplet–triplet annihilation rate is proposed.

scholarly journals Calculation of the annihilation rate of P wave quark-antiquark bound states

1976 ◽  
Vol 60 (2) ◽  
pp. 183-188 ◽  
Author(s):  
R. Barbieri ◽  
R. Gatto ◽  
R. Kögerler
Keyword(s):  
Bound States ◽  
P Wave ◽  
Annihilation Rate

Defect Nucleation and Annihilation in Sheared Polymeric Liquid Crystals

2002 ◽  
Vol 734 ◽  
Author(s):  
Dana Grecov ◽  
Alejandro D. Rey
Keyword(s):  
Liquid Crystals ◽  
Shear Rate ◽  
Long Range ◽  
Short Range ◽  
Practical Importance ◽  
Topological Defects ◽  
Annihilation Rate ◽  
Shear Rates ◽  
Parallel Array ◽  
Defect Nucleation

ABSTRACTShear–induced nucleation and annihilation of topological defects due to hydrodynamic instability in nematic liquid crystals is a phenomenon of both scientific interest and practical importance. We use a complete generalized non-linear second order tensor Landau-de Gennes model that takes into account short range order elasticity, long-range elasticity and viscous effects, to simulate the nucleation and annihilation of twist inversion walls in flow-aligning nematic polymers subjected to shear flow. Shearing a homogeneous nematic sample perpendicular to the director results in an linear instability that maybe symmetric at low shear rates, and antisymmetric at higher shear rates. At even higher shear rates the onset of nonlinearities results in the nucleation of a parallel array of twist inversion walls, such that asymmetry prevails. By increasing the shear rate the following director symmetry transition cascade is observed: symmetric → antisymmetric → asymmetric → symmetric. The nucleation of the parallel array of twist inversion walls in the asymmetric mode is due to the degeneracy in reorientation towards the shear plane. The annihilation of twist walls is mediated by twist waves along the velocity gradient direction. Twist walls annihilate by three mechanisms: wall-wall annihilations, wall-wall coalescence, and wall-bounding surface coalescence. The annihilation rate increases with increasing shear rate and at sufficiently high rates the layered structure is replaced by a homogeneously aligned system. The role of short range and long range elasticity on defect nucleation and annihilation is characterized in terms of the Deborah and Ericksen numbers. Close form solutions to approximated equations are used to explain the numerical results of the full Landau-de Gennes equations of nematodynamics.

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