Pionic probes for exotic nuclei

With the advent of meson factories such as LAMPF, powerful new tools have been added to the list of those used in the study of exotic nuclei far from the valley of stability. These new tools are reactions involving pions in the incident and/or outgoing channels. The most useful, and so far the most used of these reactions are the pion double charge exchange reactions, both (π+, π-) and (π-, π+). The (π-, π+) reaction has been successfully used to study T/sub Z/ = 3 nuclei such as 18C and 26Ne, and the (π+, π-) reaction has been used to study T/sub Z/ = -2 nuclei such as 12O, 16Ne, 24Si and 32Ar, and T/sub Z/ = -1 nuclei such as 58Zn. Perhaps the most exciting aspect of these reactions lies in the fact that they can be used to study excited states of exotic nuclei and nuclei which are slightly unbound. An example of the latter is provided by the recent identification and mass measurement of 9He. Even more exotic systems such as 7H and 5H, which are of great astrophysical interest, are the subjects of current investigations. Recently the (π-, rho) reaction has been used to identify and study 8He and 5H