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Development of a Lyman-alpha laser system for spectroscopy and laser cooling of antihydrogen

TitleDevelopment of a Lyman-alpha laser system for spectroscopy and laser cooling of antihydrogen
Publication TypeJournal Article
Year of Publication2014
AuthorsMichan, JM, Fujiwara, MC, Momose, T
Date PublishedOCT

Hydrogen Lyman-alpha radiation (121.56 nm) is important because it allows for the excitation and detection of ground-state hydrogen atoms by a one-photon process. The trapping of antihydrogen, recently reported by the ALPHA collaboration at CERN, has revived interest in Lyman-alpha lasers. In order to perform high precision tests of matter-antimatter symmetry violations or gravity-antimatter interactions with antihydrogen, laser cooling using the 1s-2p single photon transition is essential. Recent theoretical simulations predict that even with a pulsed Lyman-alpha source, laser cooling of antihydrogen would be possible. Here we describe the implementation of a high power vacuum-ultraviolet (VUV) laser at the Lyman-alpha transition of hydrogen. The VUV light was generated using a two-photon-resonant four-wave mixing process in a phase-matched mixture of krypton and argon. Two wavelengths (omega(R) -> 202.31 and omega(T) -> 602.56 nm) were mixed in a sum-difference scheme (omega(VUV) = 2 omega(R)-omega(T)) with a two-photon resonance at (4s(2)4p(5)5p{[}1/2](0) <- 4s(2)4p(6)(1S(0))) transition in Kr. With an Ar/Kr mixture of 3.9:1 we obtained 10 ns pulses of 0.1 mu J of energy at a repetition rate of 10 Hz.