Abstract

Recent observation of anomalous survival of antiprotons in dense helium media strongly suggested the creation of antiprotonic helium atoms $\overline{\text{p}}-{\text{He}}^{2+}-{\text{e}}^{-}{}^1$. If the creation of this compound is true, it is the first long-lived exotic atom containing antiprotons. Moreover, from the viewpoint of atomic and molecular spectroscopy, this new exotic atom is a quite attractive object of study, because it has both characters of atoms and molecules; in other words, it is neither an atom nor a molecule. Therefore, we attempted the laser spectroscopic investigation of this new entity in order mainly to obtain definite evidences of this creation.

© 1995 IEEE