Collisions of cold antiprotonic helium atoms and ions with ordinary helium atoms

Korenman, G.Y.; Yudin, S.N.

Авторы: Korenman G.Ya, Yudin S.N.
Журнал: Journal of Physics: Conference Series
Том: 88
Номер: 012060
Год издания: 2007
Издательство: IOP Publishing
Местоположение издательства: [Bristol, UK], England
Первая страница: 1
Последняя страница: 6
DOI: 10.1088/1742-6596/88/1/012060
Аннотация: We consider two types of collisional processes with excited antiprotonic helium systems. (i) Transitions between hyperfine structure sublevels in (\bar{p}He^{+})_{nLFJ} are considered at T =< 25 K using the coupled-channels method and a model of scalar and tensor interactions between antiprotonic and ordinary He atoms. Inelastic cross sections for the single and double spin-flip transitions are less than elastic ones by four and seven orders of magnitude, respectively. The cross sections show a resonance behaviour at E ~ 1 - 4 K, and therefore the relaxation rates, density shift and broadening of the M1 spectral lines decrease with increasing temperature from 3 to 25 K. (ii) Stark transitions and induced annihilation during collisions of the (\bar{p}He^{++})_{nl} ion with He atoms at E ~ 10 K are considered for all l-states at n ~ 30 in the framework of the coupled-channels method. In order to take into account complex energy shifts of the ns and np-states, we introduce modified boundary conditions in these channels. The main contribution to elastic scattering, Stark transitions and induced annihilations during collisions comes from the long-range polarization interaction. Admixtures of ns and np-states to nl-states (l >= 2)during collisions induce the effective annihilation cross sections for the initial l up to 15, butdon't affect the Stark cross sections for states with nearly-circular orbits. The calculated values for both types of processes are compatible with recent experimental data.
Добавил в систему: Юдин Сергей Николаевич

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Collisions of cold antiprotonic helium atoms and ions with ordinary helium atomsстатья