This review examines the numerous studies performed in recent years on atomic processes involving ``cold'' hydrogen atoms in the gas phase and at a surface. The term ``cold'' atom denotes the range of relative collision energies $E$ < 10 meV (correspondingly, ``ultracold'' atoms have $E\lesssim$ 1 meV). This corresponds to the temperature range of tens (or units) of kelvins. Three main fields of study in which extensive experimental programs have been realized are treated: the study of collision processes involving hydrogen atoms, which are of astrophysical interest; the study of elastic atom-molecule scattering at ultralow energies; and studies on the problem of condensed hydrogen. The fundamental technical means of realization and the results obtained from the studies are discussed.

%0 Journal Article
%T Experiments with cold hydrogen atoms
%A V. B. Leonas
%I Physics-Uspekhi
%D 1981
%J Phys. Usp.
%V 24
%N 4
%P 318-330
%U https://ufn.ru/en/articles/1981/4/d/
%U https://doi.org/10.1070/PU1981v024n04ABEH004811