scholarly journals Renormalised Perturbation Theory of Resonant Multiphoton Ionisation

1995 ◽  
Vol 48 (5) ◽  
pp. 835
Author(s):  
K Unnikrishnan
Keyword(s):  
Perturbation Theory ◽  
Cross Sections ◽  
Bound States ◽  
Resonance Region ◽  
Short Pulses ◽  
Total Cross Sections ◽  
Two Photon ◽  
Continuum States ◽  
The Mean ◽  
Good Agreement

Perturbation theory of multiphoton ionisation due to a classical electromagnetic field is modified to allow for intermediate resonances with bound states. Complex energies, generally associated with resonances, do not enter into this formalism. For a monochromatic field of frequency u, a constant ionisation rate can then be defined unambiguously and only such continuum states are excited which correspond to the absorption of energy in integral multiples of hu. As an application, differential and total cross sections for the two-photon ionisation of hydrogen, for frequencies below the n = 3 resonance region, are obtained in closed form. Existing data for generalised cross sections, calculated numerically using the complex coordinate method, are in good agreement with the present results. Finally, the mean fractional ionisation resulting from a pulse of finite duration is estimated on the basis of the associated power spectrum. For short pulses, the time dependence of ionisation exhibits a departure from that expected of a time-independent rate.

Reaction rate of n12C radiative capture at temperature from 0.01 to 10 T9

2021 ◽  
pp. 142-148
Author(s):  
S.B. Dubovichenko ◽  
◽  
N.A. Burkova ◽  
R.R. Shamitova ◽  
◽  
...  
Keyword(s):  
Cross Sections ◽  
Cluster Model ◽  
Bound States ◽  
Reaction Rate ◽  
Applied Research ◽  
Radiative Capture ◽  
Potential Cluster Model ◽  
Total Cross Sections ◽  
Forbidden States ◽  
Wide Resonance

Within the framework of a modified potential cluster model with forbidden states, radiation n12C capture at energies from 10-5 keV to 5 MeV is considered, taking into account a wide resonance at Ex = 8.2 MeV. It is shown that on the basis of potentials that are consistent with the energies of the bound states, it is possible to correctly transfer the available experimental data. Based on the obtained total cross sections, the n12C capture reaction rate was calculated. The results for reaction rate are approximated by simple expressions, which simplifies their use in applied research.

scholarly journals Energy Dependence of Total Cross Sections for Reactions with 4, 6he, 6, 7, 9li Nuclei

KnE Energy ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 21
Author(s):  
Yu Penionzhkevich ◽  
Yu Sobolev ◽  
V Samarin ◽  
M Naumenko
Keyword(s):  
Experimental Data ◽  
Energy Range ◽  
Numerical Solution ◽  
Energy Dependence ◽  
Cross Sections ◽  
Beam Energy ◽  
Microscopic Analysis ◽  
Time Dependent ◽  
Total Cross Sections ◽  
Good Agreement

The paper presents the results of measurement of the total cross sections for reactions 4,6He + Si and 6,7,9Li + Si in the beam energy range 5−50 A⋅MeV. The enhancements of the total cross sections for reaction 6He + Si compared with reaction 4He + Si, and 9Li + Si compared with reactions 6,7Li + Si have been observed. The performed microscopic analysis of total cross sections for reactions 6He + Si and 9Li + Si based on numerical solution of the time-dependent Schrödinger equation for external neutrons of projectile nuclei 6He and 9Li yielded good agreement with experimental data.

scholarly journals The Dynamics of the S(1D)+H2/D2 Reactions at Low Temperature via Statistical Simulations

2020 ◽  
Vol 3 (1) ◽  
pp. 9-16
Author(s):  
Tomas Gonzalez-Lezana ◽  
Pascal Larrégaray ◽  
Laurent Bonnet
Keyword(s):  
Cross Sections ◽  
Quantum Model ◽  
Space Theory ◽  
Collisional Energy ◽  
Energy Regime ◽  
Phase Space Theory ◽  
The Mean ◽  
Statistical Approaches ◽  
Theoretical Results ◽  
Good Agreement

Two different statistical approaches, the statistical quantum model (SQM) and the mean potential phase space theory (MPPST), have been employed to calculate the integral cross sections for the reactive collisions between S(1D) and H2/ D2  in the low energy regime (below 0.3 eV collisional energy). The rate constant for the S(1D) + H2 → SH + H reaction has been also obtained and compared with previously reported experimental and theoretical results. The good agreement shows the capability of these two methods to study the dynamics of these complex-forming atom-diatom processes in the present energy regime.

scholarly journals Calculations of Electron Loss to Continuum in Collisions of Li- and Be-Like Uranium Ions with Nitrogen Targets

Atoms ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 89
Author(s):  
Andrey I. Bondarev ◽  
Yury S. Kozhedub ◽  
Ilya I. Tupitsyn ◽  
Vladimir M. Shabaev ◽  
Günter Plunien
Keyword(s):  
Perturbation Theory ◽  
Energy Distribution ◽  
Cross Sections ◽  
Differential Cross ◽  
Differential Cross Sections ◽  
Electron Loss ◽  
First Order ◽  
Uranium Ions ◽  
Relativistic Perturbation Theory ◽  
Good Agreement

Doubly differential cross sections for projectile ionization in fast collisions of few-electron uranium ions with the nitrogen target are calculated within the first order of the relativistic perturbation theory. A comparison with the recent measurements of the energy distribution of forward-emitted electrons is made and good agreement is found.

Measurement of total cross sections for π0 photoproduction on nuclei in the Δ-resonance region

1986 ◽  
Vol 454 (3-4) ◽  
pp. 579-588 ◽  
Author(s):  
J. Arends ◽  
P. Detemple ◽  
N. Floss ◽  
A. Hegerath ◽  
S. Huthmacher ◽  
...  
Keyword(s):  
Cross Sections ◽  
Resonance Region ◽  
Total Cross Sections

scholarly journals Elastic Scattering of Electron and Positron by Radium and Radon Atoms

2021 ◽  
Vol 13 (01) ◽  
pp. 1-11
Author(s):  
A .K. Yassir ◽  
◽  
A. H. Hussain ◽  
F. A. Ali ◽  
◽  
...  
Keyword(s):  
Elastic Scattering ◽  
Cross Sections ◽  
Differential Cross ◽  
Exchange Potential ◽  
Positron Scattering ◽  
Total Cross Sections ◽  
Total Potential ◽  
Correlation Potential ◽  
Experimental Values ◽  
Good Agreement

The Differential Cross Sections (DCS's), Total Cross Sections (TCS's) and Momentum Transfer Cross Sections (MTCS's) of electron and positron scattering by radium and radon atoms were calculated in the range of energy (5–500) eV using a total potential consisting of combining the static, exchange and polarization potentials at long distances. In addition, the correlation potential of Perdew–Zunger at short distances for electrons was used, as well as the correlation potential of Jain for positrons. The exchange potential for positrons was neglected. In this study, a good agreement with other experimental values and theoretical values of many investigators was found.

scholarly journals Cross sections of proton capture reactions of Sr isotopes

2019 ◽  
Vol 11 ◽  
Author(s):  
S. Galanopoulos ◽  
P. Demetriou ◽  
M. Kokkoris ◽  
G. Kriembardis ◽  
S. Harissopulos ◽  
...  
Keyword(s):  
Cross Sections ◽  
Relative Efficiency ◽  
Background Suppression ◽  
Proton Capture ◽  
Total Cross Sections ◽  
Model Code ◽  
Hpge Detectors ◽  
Theoretical Predictions ◽  
Compton Background ◽  
Good Agreement

Cross section measurements of the proton capture reactions of the 86Sr, 87Sr and 88Sr isotopes were carried out at energies Ep=1.4-5 MeV. At Ep <3.5 MeV an array of 4 HPGe detectors with 100% relative efficiency shielded with BGO scintillators for Compton background suppression was used, whereas at Ep >3.5 MeV, the measurements were performed by means of one HPGe detector of 80% relative efficiency. For the 87Sr(p,7)88Y and 88Sr(p,7)89Y reactions total cross sections ranging from 0.5 μο-5 mb were found. The data analysis of the 86Sr(p,7)87Y reaction is in progress. Cross sections have also been calculated by means of the statistical model code MOST. A very good agreement between the experimental data and the theoretical predictions has been found.

scholarly journals Single electron capture into arbitrary states of bare projectiles from multi-electron targets

2018 ◽  
Vol 16 (2) ◽  
pp. 239-247
Author(s):  
Nenad Milojevic ◽  
Ivan Mancev
Keyword(s):  
Electron Capture ◽  
Cross Sections ◽  
Single Electron ◽  
Final States ◽  
Total Cross Sections ◽  
Single Electron Capture ◽  
Body Boundary ◽  
Impact Energies ◽  
Good Agreement ◽  
Prior Form

The prior form of four-body boundary-corrected first Born (CB1-4B) method is applied to calculate the total cross sections for single electron capture from the Kshell of multi-electron atoms (C, N, O, Ar) by fast projectiles (H+, He2+and Li3+). All calculations are carried out for electron capture into the arbitrary n, l, and m final states of the projectiles. The present results are found to be in very good agreement with the available experimental data at intermediate and high impact energies.

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