Hadronic atom

Article By:

Wiegand, Clyde E. Lawrence Berkeley Laboratory, University of California, Berkeley, California.

Povh, Bogdan Max-Planck Institut für Kernphysik, Saupfercheckweg, Germany.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.304600

A hydrogenlike system that consists of a strongly interacting particle (hadron) bound in the Coulomb field and in orbit around any ordinary nucleus. The kinds of hadronic atoms that have been made and the years in which they were first identified include pionic (1952), kaonic (1966), Σ⁻ hyperonic (1968), and antiprotonic (1970). They were made by stopping beams of negatively charged hadrons in suitable targets of various elements, for example, potassium, zinc, or lead. The lifetime of these atoms is of the order of 10⁻¹² s, but this is long enough to identify them and study their characteristics by means of their x-ray spectra. They are available for study only in the beams of particle accelerators. Pionic atoms can be made by synchrocyclotrons and linear accelerators in the 500-MeV range. The others can be generated only at accelerators where the energies are greater than about 6 GeV. See also: Elementary particle; Hadron; Particle accelerator

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