Nonadiabatic transition probabilities in a time-dependent Gaussian pulse or plateau pulse: Toward experimental tests of the differences from Dirac’s transition probabilities

2018 ◽  
Vol 149 (20) ◽  
pp. 204110 ◽  
Author(s):  
Anirban Mandal ◽  
Katharine L. C. Hunt
Keyword(s):  
Transition Probabilities ◽  
Experimental Tests ◽  
Time Dependent ◽  
Gaussian Pulse ◽  
Nonadiabatic Transition

scholarly journals Determination and Fire Analysis of Gob Characteristics Using CFD

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5274
Author(s):  
Florencio Fernández-Alaiz ◽  
Ana Maria Castañón ◽  
Fernando Gómez-Fernández ◽  
Antonio Bernardo-Sánchez ◽  
Marc Bascompta
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Experimental Tests ◽  
The Self ◽  
Time Dependent ◽  
Scale Analysis ◽  
Dynamics Modelling ◽  
Gob Area ◽  
Time Dependent Analysis ◽  
Waste Coal

A laboratory-scale analysis using coal from an underground mine was carried out, emulating a mixture from the gob area in an actual mine, consisting of waste, coal, and free space for the flow of air. Experimental tests and computational fluid dynamics modelling were done to define and verify the behavior of the collapsed region in a time-dependent analysis. In addition, the characteristics of coal were defined, regarding the self-combustion, combustion rate, and pollutants generated in each stage of the fire. The results achieved are useful for determining the behavior of the collapsed area in full-scale conditions and to provide valuable information to study different scenarios of a potential fire in a real sublevel coal mine regarding how the heat is spread in the gob and how pollutants are generated.

NONADIABATIC TRANSITION OF THE FISSIONING NUCLEUS AT SCISSION: THE TIME SCALE

2012 ◽  
Vol 21 (05) ◽  
pp. 1250031 ◽  
Author(s):  
N. CARJAN ◽  
M. RIZEA
Keyword(s):  
Time Dependent ◽  
Time Interval ◽  
Short Time Interval ◽  
Excitation Energies ◽  
Nonadiabatic Transition ◽  
Dependent Potential ◽  
Sudden Approximation ◽  
Transition Times ◽  
Short Time ◽  
Neutron Multiplicities

A time-dependent approach to the scission process, i.e., to the transition from two fragments connected by a thin neck (deformation αi) to two separated fragments (deformation αf) is presented. This transition is supposed to take place in a very short time interval ΔT. Our approach follows the evolution from αi to αf of all occupied neutron states by solving numerically the two-dimensional time-dependent Schrödinger equation with time-dependent potential. Calculations are performed for mass divisions from AL = 70 to AL = 118(AL being the light fragment mass) taking into account all neutron states (Ω = 1/2, 3/2, …, 11/2) that are bound in 236 U at αi. ΔT is taken as parameter having values from 0.25×10-22 to 6×10-22 s. The resulting scission neutron multiplicities ν sc and primary fragments' excitation energies [Formula: see text] are compared with those obtained in the frame of the sudden approximation (ΔT = 0). As expected, shorter is the transition time more excited are the fragments and more neutrons are emitted, the sudden approximation being an upper limit. For ΔT = 10-22 which is a realistic value, the time dependent results are 20% below this limit. For transition times longer than 6×10-22 s the adiabatic limit is reached: No scission neutrons are emitted anymore and the excitation energy at αf is negligible.

scholarly journals Population of Excited States of Al10+ in a Plasma by a Time-Dependent Model

1984 ◽  
Vol 86 ◽  
pp. 221-224
Author(s):  
H. Guennou ◽  
A. Sureau
Keyword(s):  
Population Distribution ◽  
Transition Probabilities ◽  
Ground Level ◽  
Radiative Transition ◽  
Time Dependent ◽  
Hartree Fock ◽  
Ion Collisions ◽  
Finite Set ◽  
Dependent Model ◽  
Time Dependent Model

The present model is the time-dependent version of a previous model (Sureau et al. 1983) in which the population distribution was assumed in steady state. A finite set of levels is partitioned in four subsets: the Z-ion ground-level and, contingently, the first near-degenerated levels (subset 1); all the successive excited Z-ion levels up to n=5 (subset 2); a finite number of higher Rydberg levels (because of the limitation of the series in the plasmas) which are assumed in LTE with the Z+l−ion ground-level (subset 3, called the thermal band); and the Z+l ion ground-level (subset 4).The physical processes explicitly considered are the radiative cascades and the transitions between the Z-ion bound levels induced by electron-ion collisions. The radiative-transition probabilities are given by ab-initio calculations using a modified Hartree-Fock method including the spin-orbit interaction (Sureau et al., 1984). The collision rates are derived by the Van Regemorter formula multiplied by an adjustable parameter Fc.

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