Positron-impact ionization of atomic hydrogen in the distorted-wave polarized-orbital method

1990 ◽  
Vol 68 (2) ◽  
pp. 249-252 ◽  
Author(s):  
K. K. Mukherjee ◽  
Keka Basu Choudhury ◽  
N. Ranjit Singh ◽  
P. S. Mazumdar ◽  
S. Brajamani
Keyword(s):  
Cross Sections ◽  
Atomic Hydrogen ◽  
Impact Ionization ◽  
Theoretical Calculations ◽  
Orbital Method ◽  
Distorted Wave ◽  
Positron Impact ◽  
Positron Energy ◽  
The Matrix ◽  
Final Channel

Calculations are performed for the total cross sections for the positron-impact ionization of the ground state of atomic hydrogen, employing the distorted wave polarized orbital method. This explicitly takes into account the matrix elements arising from the distorted part of the target wave function and the effect of final-channel distortion in the incident-positron energy range 20.4–68 eV. The results are compared with available theoretical calculations.

Positron-impact ionization of hydrogen atoms

1985 ◽  
Vol 63 (5) ◽  
pp. 621-624 ◽  
Author(s):  
A. S. Ghosh ◽  
P. S. Majumdar ◽  
Madhumita Basu
Keyword(s):  
Cross Section ◽  
Ionization Cross Section ◽  
Impact Ionization ◽  
Orbital Method ◽  
Distorted Wave ◽  
Positron Impact ◽  
Hydrogen Atoms ◽  
Ionization Cross ◽  
Channel Wave ◽  
Final Channel

The ionization cross section of hydrogen atoms by positron impact has been calculated by using a distorted-wave polarized-orbital method. We have employed two models depending on the choice of the final-channel wave function, and the two sets of results differ dramatically. We have also found that below 100 eV the total positron-impact ionization cross section including positronium formation is appreciably larger than the corresponding results for electron-impact ionization.

Positron-impact ionization of helium in the distorted-wave polarized-orbital method

1989 ◽  
Vol 39 (4) ◽  
pp. 1756-1759 ◽  
Author(s):  
K. K. Mukherjee ◽  
P. S. Mazumdar ◽  
S. Brajamani
Keyword(s):  
Impact Ionization ◽  
Orbital Method ◽  
Distorted Wave ◽  
Positron Impact

Total cross section for electron-impact ionization from the ground state of atomic hydrogen using the distorted-wave polarized orbital method

1988 ◽  
Vol 66 (5) ◽  
pp. 399-401 ◽  
Author(s):  
K. K. Mukherjee ◽  
P. S. Mazumdar ◽  
S. Brajamani
Keyword(s):  
Total Cross Section ◽  
Electron Impact ◽  
Cross Section ◽  
Ground State ◽  
Atomic Hydrogen ◽  
Impact Ionization ◽  
Electron Impact Ionization ◽  
Orbital Method ◽  
Present Calculation ◽  
Distorted Wave

The total cross-section for electron-impact ionization from the ground state of atomic hydrogen is studied by using the distorted-wave polarized orbital method. In the present calculation we have taken into account the matrix elements arising from the distorted part of the target wave function. The present results are in good agreement with experimental findings.

scholarly journals Positron Impact Excitation of the nS States of Atomic Hydrogen

Atoms ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 9 ◽  
Author(s):  
Anand K. Bhatia
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Born Approximation ◽  
Atomic Hydrogen ◽  
Impact Excitation ◽  
Orbital Method ◽  
Positron Impact ◽  
Excitation Cross Sections ◽  
Theoretical Results ◽  
Incident Positron

The excitation cross sections of the nS states, n = 2 to 6, of atomic hydrogen at various incident positron energies (10.23 to 300 eV) were calculated using the variational polarized-orbital method. Nine partial waves were used to obtain converged cross sections. The present results should be useful for comparison with results obtained from other theories and approximations. The positron-impact cross section was found to be higher than the electron-impact cross sections. Experimental and other theoretical results are discussed. The threshold law of excitation is discussed and the cross sections in this region were seen to obey the threshold law proportional to ( ln k f ) − 2 . Cross sections were calculated in the Born approximation also and compared to those obtained using the variational polarized orbital method.

Positron impact ionization of krypton and xenon

2000 ◽  
Vol 77 (10) ◽  
pp. 769-774 ◽  
Author(s):  
R I Campeanu ◽  
R P McEachran ◽  
A D Stauffer
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Free Electron ◽  
Impact Ionization ◽  
Plane Waves ◽  
Distorted Wave ◽  
Positron Impact ◽  
Full Energy ◽  
Alternate Model ◽  
Wave Models

Several distorted-wave models for positron ionization of krypton and xenon are investigated. Our previous CPE (Coulomb plus Plane waves -- full Energy range) model produces reliable cross sections for krypton. For xenon, at high positron energies, the CPE results fall below experiment. We have proposed an alternate model DCPE4 that works well for both krypton and xenon. A common feature of both of these models is that the free electron and positron are treated differently.PACS No.: 34.90.+q

Doubly differential cross sections for electron impact ionization of atomic hydrogen

1992 ◽  
Vol 70 (12) ◽  
pp. 1309-1311 ◽  
Author(s):  
H. Ray ◽  
A. C. Roy ◽  
U. Werner
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Differential Cross ◽  
Atomic Hydrogen ◽  
Impact Ionization ◽  
Theoretical Calculations ◽  
Electron Impact Ionization ◽  
Differential Cross Sections ◽  
Secondary Electrons ◽  
Primary Electrons

The Glauber approximation is used to calculate doubly differential cross sections (DDC's) for electron impact ionization of atomic hydrogen at incident energies of 100, 150, and 250 eV. The angular dependences of DDC's are presented for the scattered (primary) electrons. The energies of ejected (secondary) electrons were chosen to be 5, 10, and 14 eV. A comparison is made of the present DDC's with the results of other theoretical calculations.

Double differential cross sections in the electron impact ionization of helium

1994 ◽  
Vol 72 (3-4) ◽  
pp. 126-129 ◽  
Author(s):  
S. Brajamani ◽  
N. Ranjit Singh ◽  
M. Babuyaima ◽  
P. S. Mazumdar
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Differential Cross ◽  
Impact Ionization ◽  
Electron Impact Ionization ◽  
Differential Cross Sections ◽  
Distorted Wave ◽  
Distorted Wave Born Approximation ◽  
Wave Approximation ◽  
Final Channel

The double differential cross sections for electron impact ionization of helium are evaluated in the framework of a distorted wave approximation that takes into account the effects of initial channel, final channel, and target distortion. The present results are in fair agreement with the measured values and rigorous DWBA (distorted-wave Born approximation) results of McCarthy and Zhang.

scholarly journals Excitations of the nS States of Atomic Hydrogen by Electron Impact, Excitation Rate Coefficients, and Phase Shifts: Comparison with Positron Impact Excitation

Atoms ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Anand K. Bhatia
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
Phase Shifts ◽  
Impact Excitation ◽  
Rate Coefficients ◽  
Orbital Method ◽  
Positron Impact ◽  
Excitation Rate ◽  
Excitation Cross Sections

The excitation cross-sections of the nS states of atomic hydrogen, n = 2 to 6, by electron impact on the ground state of atomic hydrogen were calculated using the variational polarized-orbital method at various incident electron energies in the range 10 to 122 eV. Converged excitation cross-sections were obtained using sixteen partial waves (L = 0 to 15). Excitation cross-sections to 2S state, calculated earlier, were calculated at higher energies than before. Results obtained using the hybrid theory (variational polarized orbital method) are compared to those obtained using other approaches such as the Born–Oppenheimer, close-coupling, R-matrix, and complex-exterior scaling methods using only the spherical symmetric wave functions. Phase shifts and elastic cross-sections are given at various energies and angular momenta. Excitation rate coefficients were calculated at various electron temperatures, which are required for plasma diagnostics in solar and astrophysics to infer plasma parameters. Excitation cross-sections are compared with those obtained by positron impact excitation.

scholarly journals Positron Impact Excitation of the 2S State of Atomic Hydrogen

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 69 ◽  
Author(s):  
A.K. Bhatia
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
Threshold Energy ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Orbital Method ◽  
Positron Impact ◽  
Excitation Cross Sections ◽  
Incident Positron

The excitation cross-sections of the 2S state of atomic hydrogen at low (near threshold energy) to high incident positron energies (10.30 to 300 eV) have been calculated using the variational polarized-orbital method. Nine partial waves have been used to obtain converged cross-sections in the above energy range. The cross sections compared to the electron-impact excitation of the S state of atomic hydrogen are larger in the present case. The maximum cross section is 3.63(−1) π a 0 2 at 16.5 eV compared to 1.37(−1) π a 0 2 at 11.14 eV for the electron-impact excitation. The present results are compared with other calculations. Cross-sections have also been calculated in the Born approximation in which the polarization of the target has been included. Differential cross sections were calculated at k = 1.0 (13.6eV), 2.5 (85 eV), 3.483 (200 3V), and 4.696 (300 eV).

Sign in / Sign up

Export Citation Format

Share Document