Publications

A low energy positron beam is used to study the behavior of positrons in low density (~~10(-3)Torr) H2 and He.

A series of balloon and satellite measurements dating back to 1970 have established the existence of a powerful, compact and variable source of electron-positron annihilation line (511 keV) radiati

The implementation and application of the first brightness enhanced slow positron beam is described.

Using a beam of slow positrons in ultrahigh vacuum, we estimate the positron mean free path and energy loss rate and measure the inelastic thresholds due to exciton, electron-hole pair, and positro

Clusters of four atomic vacancies were found in Au nanoparticle-embedded MgO by positron lifetime spectroscopy {[}Phys. Rev. Lett. 83, 4586 (1999)].

The universal relations between the Kosterlitz-Thouless transition temperature T sub c and the superfluid sheet density of thin-film semiconductors with mean-field transition temperature T sub (co)

We present magnetic field data from the cusp-latitude South Pole station that exhibit, under appropriate local time and interplanetary magnetic field conditions, the signature predicted by recent m

Previous investigators have ruled out neutral atomic H as a possible medium for prompt annihilation of galactic positrons principally because the expected two-photon positronium spectrum is wider t

We have measured the magnetoresistance of a very low density and extremely high quality two-dimensional hole system.

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