Laser is a powerful tool for precise spectroscopy and has been used in many different fields of physics. In this paper we present interesting and important examples of laser spectroscopy applied in the field of atomic physics involving an exotic particle `antiproton'. We have performed laser spectroscopy of metastable antiprotonic helium atoms (or atom-molecules) (pHe+) and have observed a density dependence of the resonance vacuum wavelengths for the known transitions (n,1) equals *(39,35) yields (38,34) and (37,34) yields (36,33).
Hiroyuki A. Torii, Hiroyuki A. Torii,
"Laser spectroscopy and applications in antiproton science", Proc. SPIE 4002, Saratov Fall Meeting '99: Laser Physics and Spectroscopy, (20 March 2000); doi: 10.1117/12.380109; https://doi.org/10.1117/12.380109