Polarization of Lyman-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>Radiation Produced by Direct Excitation of Hydrogen Atoms by Photon Impact

Kauppila, W. E.; Teubner, P. J. O.; Fite, W. L.; Girnius, R. J.

doi:10.1103/physreva.2.1759

Cited by 29 publications

(9 citation statements)

References 9 publications

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“…H(2s) AND H(2p) P R O D U C T IO N 559 incident proton energy, keV F igure 14. The polarization 77 of the Lyman-a radiation, produced by direct excitation of hydrogen atoms by proton-impact, against incident proton energy E. o, Experimental values of Kauppila (1970); , this work (six states);----, Gaussorgues & Salin (1971); ; -• Gallaher & Wilets (1968).…”

Section: T Otal Cross Sections For H (2 S) and H (2 P ) Productionmentioning

confidence: 89%

“…The polarization 77 of the emitted Lyman-a radiation for direct excitation has been measured by Kauppila et al (1970) (Percival & Seaton 1958). The results are presented in figure 14 along with other theoretical predictions.…”

Section: T Otal Cross Sections For H (2 S) and H (2 P ) Productionmentioning

confidence: 99%

“…Smith 1964, 1967Crothers et al 1968;Knudson & Thorson 1970;Kubac Matveenko & Ponomarev 1975;Hunter & Kuriyan 1977 a, 6;Davis & Thorson 1978). In the last sixteen years there have been a number of experiments (Lockwood & Everhart 1962, Helbig & Everhart 1965Stebbings et al 19^5> Ryding et al 1966;Young et al 1969Young et al , 1970Kauppila et al 1970;Morgan et al 19735 Houver et etal. 1976;Chong & Fite 1977;Park et al 1978).…”

Section: Introductionmentioning

confidence: 99%

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Proton-hydrogen collisions: Differential and total cross sections for H(2s) and H(2p) production in the 1—7 keV range

Crothers

Hughes

1979

Phil. Trans. R. Soc. Lond. A

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A multistate molecular approach to the proton—hydrogen collision is formulated in terms of an impact parameter perturbed stationary-states approximation. Spurious long range couplings are avoided and Galilean invariance is enforced by the inclusion of momentum translation factors which are determined variationally within an Euler-Lagrange formalism (Crothers & Hughes 1978). Well defined radial and rotational coupling matrix elements are employed in the 1-7 keV impact energy range in a six-state (lso g , 2po u , 2pπ u , 3po u , 3pπ g , 4fo u ) calculation of elastic and inelastic differential scattering cross sections, charge exchange probabilities and both direct and exchange H (2p) production total cross sections. They are also employed in the same energy range in a ten-state (1so g , 2po u , 3dπ g , 2pπ u , 2so g , 3po u , 3do g , 4fo u , 4dπ g , 3pπ u ) calculation of both direct and exchange H (2s) production total cross sections. The results are in excellent accord with experimental data and show considerable improvement on previous molecular calculations. This success is attributed to the inclusion of both momentum translation factors and radial coupling matrix elements.

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Section: T Otal Cross Sections For H (2 S) and H (2 P ) Productionmentioning

confidence: 89%

Section: T Otal Cross Sections For H (2 S) and H (2 P ) Productionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Proton-hydrogen collisions: Differential and total cross sections for H(2s) and H(2p) production in the 1—7 keV range

Crothers

Hughes

1979

Phil. Trans. R. Soc. Lond. A

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“…Both computational and experimental results for Lyα suggest polarizations in the range of 10% -25% (Kauppila et al 1970;Hippler et al 1988;McLaughlin, Winter & McCann, 1997;Keim et al 2005). Laming (1990b) suggests that at these energies it is appropriate to assume that the Hα polarization is the same as the Lyα polarization for the same energy photons.…”

Section: At Such Energies the Contribution To Line Polarization For Ementioning

confidence: 99%

Polarization Diagnostics for Cool Core Cluster Emission Lines

Sparks

Pringle

Carswell

et al. 2013

ApJ

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The nature of the interaction between low-excitation gas filaments at ∼ 10 4 K, seen in optical line emission, and diffuse X-ray emitting coronal gas at ∼ 10 7 K in the centers of galaxy clusters remains a puzzle. The presence of a strong, empirical correlation between the two gas phases is indicative of a fundamental relationship between them, though as yet of undetermined cause. The cooler filaments, originally thought to have condensed from the hot gas, could also arise from a merger or the disturbance of cool circumnuclear gas by nuclear activity.Here, we have searched for intrinsic line emission polarization in cool core galaxy clusters as a diagnostic of fundamental transport processes. Drawing on developments in solar astrophysics, direct energetic particle impact induced polarization holds the promise to definitively determine the role of collisional processes such as thermal conduction in the ISM physics of galaxy clusters, while providing insight into other highly anisotropic excitation mechanisms such as shocks, intense radiation fields and suprathermal particles. Under certain physical conditions, theoretical calculations predict of order ten percent polarization. Our observations of the filaments in four nearby cool core clusters place stringent upper limits ( 0.1%) on the presence of emission line polarization, requiring that if thermal conduction is operative, the thermal gradients are not in the saturated regime. This limit is consistent with theoretical models of the thermal structure of filament interfaces.

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“…This coefficient includes a large amount of information about the internal structure of atomic or molecular targets and is thus an important parameter. Currently, there are inconsistent theoretical results reported for reaction (1) in the literature, for impact energies of less than 25 keV [11,12]. On the other hand, there are not enough independent experimental and theoretical results reported for this coefficient at medium or high impact energies.…”

Section: Introductionmentioning

confidence: 95%

Polarization of Lyman-α and Balmer-α emission in proton–hydrogen collisions: a study using first-order Born–Faddeev-type equations

Fathi

Bolorizadeh

Akbarabadi

et al. 2012

J. Phys. B: At. Mol. Opt. Phys.

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A three-body Born-Faddeev model is devised to calculate the total cross sections of Balmer-α and Lyman-α emissions, for the excitation of hydrogen atoms by proton impact in the energy range of 100 keV-7 MeV. In addition, the polarization alignment factor A 20 is calculated and compared against available experimental data to further test the theory. Specifically, here we use the Faddeev-Watson-Lovelace formalism to study the excitation of atomic hydrogen from its ground state to the excited states of n = 2 and 3 and magnetic sublevels l = 0, 1 and 2, wherever applicable. The first-order electronic, A (1) e , and the first-order nuclear, A (1) n , amplitudes are considered in order to calculate the excitation transition matrix (T PT ), while a near-the-shell condition is assumed throughout. In addition, our results were used to calculate the first-order form factors. The present results are compared, where possible, with those of other theoretical and experimental works that are currently available in the literature.

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Polarization of Lyman-αRadiation Produced by Direct Excitation of Hydrogen Atoms by Photon Impact

Cited by 29 publications

References 9 publications

Proton-hydrogen collisions: Differential and total cross sections for H(2s) and H(2p) production in the 1—7 keV range

Proton-hydrogen collisions: Differential and total cross sections for H(2s) and H(2p) production in the 1—7 keV range

Polarization Diagnostics for Cool Core Cluster Emission Lines

Polarization of Lyman-α and Balmer-α emission in proton–hydrogen collisions: a study using first-order Born–Faddeev-type equations

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