Excitation of hydrogen atom by proton and antiproton

Sabbah, A. S.; Tantawi, Reda S.

doi:10.1007/bf02532289

Cited by 6 publications

(6 citation statements)

References 10 publications

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Section: Discussionmentioning

confidence: 66%

“…In a similar situation, proton-impact cross-sections were calculated by Saxena et al [16], Cheshire and Sullivan [17], and Kolakowska et al [18]. However, Sabbah and Tantawi [19] calculated cross-sections by proton impact as well as by antiproton impact. Their results are shown in Figure 2 of Reference [19] and they are seen to be of the same order, with the difference being that the proton impact cross-sections had a maximum at about 50 keV, just as in the present calculation, while the antiproton cross-sections decreased monotonically with the increase of the incident energy.…”

Section: Discussionmentioning

confidence: 66%

“…However, Sabbah and Tantawi [19] calculated cross-sections by proton impact as well as by antiproton impact. Their results are shown in Figure 2 of Reference [19] and they are seen to be of the same order, with the difference being that the proton impact cross-sections had a maximum at about 50 keV, just as in the present calculation, while the antiproton cross-sections decreased monotonically with the increase of the incident energy. Figure 2 of Reference [19] is plotted using a log scale, and as such, it is very difficult to extract meaningful results.…”

Section: Discussionmentioning

confidence: 99%

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Positron Impact Excitation of the 2S State of Atomic Hydrogen

Bhatia

2019

Atoms

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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).

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Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 99%

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Positron Impact Excitation of the 2S State of Atomic Hydrogen

Bhatia

2019

Atoms

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“…The expression (58), when compared with the corresponding one for hermitian matrices (13), leads immediately to the following observation: if the parameter η is chosen in [1/2, 1] and η := 2η − 1, then the two ensembles (real and complex) get twinned, i.e. they share the same spectral properties, despite belonging to different classes of invariance and having even a different number of independent variables.…”

Section: Different Dyson Class βmentioning

confidence: 99%

On invariant 2×2 β -ensembles of random matrices

Vivo

Majumdar

2008

Physica A: Statistical Mechanics and its Applications

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We introduce and solve exactly a family of invariant 2×2 random matrices, depending on one parameter η, and we show that rotational invariance and real Dyson index β are not incompatible properties. The probability density for the entries contains a weight function and a multiple trace-trace interaction term, which corresponds to the representation of the Vandermonde-squared coupling on the basis of power sums. As a result, the effective Dyson index β eff of the ensemble can take any real value in an interval. Two weight functions (Gaussian and non-Gaussian) are explored in detail and the connections with β-ensembles of Dumitriu-Edelman and the so-called Poisson-Wigner crossover for the level spacing are respectively highlighted. A curious spectral twinning between ensembles of different symmetry classes is unveiled: as a consequence, the identification between symmetry group (orthogonal, unitary or symplectic) and the exponent of the Vandermonde (β = 1, 2, 4) is shown to be potentially deceptive. The proposed technical tool more generically allows for designing actual matrix models which i) are rotationally invariant; ii) have a real Dyson index β eff ; iii) have a pre-assigned confining potential or alternatively level-spacing profile. The analytical results have been checked through numerical simulations with Preprint submitted to Elsevier 8 March 2018an excellent agreement. Eventually, we discuss possible generalizations and further directions of research.

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“…An impact parameter approach, based on a onecenter expansion in atomic orbitals, was applied to study the influence of the sign of the projectile charge, [14] and the back couplings to the initial state, [15] on the impact excitation of H(1𝑠) atoms by protons and antiprotons. It was found that the backcoupling reduces the cross sections and plays an important role in the case of the antiproton scattering being much larger than in the proton case.…”

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confidence: 99%

Impact Excitations of Hydrogen Atoms in Collisions with Protons and Antiprotons

Tantawi

Nassar

2014

Chinese Phys. Lett.

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The direct impact excitations of ground-state hydrogen atoms by protons and antiprotons are investigated by using an impact parameter treatment. The calculations are performed within the solution of the coupled differential equations arising from the one-center atomic-orbital close-coupling approach as well as the impact parameter version of the first and second Born approximations. We have considered calculations that allow couplings to the 𝑛=1-5 states (up to g sub-levels) of the target atom as well as others, which neglect the effect of all states other than the initial and final states of the target atom. The sensitivity of the cross sections to the charge of the projectile is studied. The calculated cross sections are compared with those obtained by previous theoretical and experimental results.

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Excitation of hydrogen atom by proton and antiproton

Cited by 6 publications

References 10 publications

Positron Impact Excitation of the 2S State of Atomic Hydrogen

Positron Impact Excitation of the 2S State of Atomic Hydrogen

On invariant 2×2 β -ensembles of random matrices

Impact Excitations of Hydrogen Atoms in Collisions with Protons and Antiprotons

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