Inelastic scattering and single and double charge exchange reactions within the A=27 isobaric multiplet

Angular distributions for the reactions $\sp{27}$Al, $\sp{28}$Si($\pi\sp{\pm}$,$\pi\sp{\pm}$) at T$\sb\pi$ = 180 MeV and an excitation function at $\theta\sb{\rm lab.}$ = 5$\sp{\rm o}$ for the reaction $\rm\sp{27}Al(\pi\sp{+},\pi\sp{-})\sp{27}P$ were measured using the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility in Los Alamos, New Mexico. Angular distributions for the reaction $\sp{27}$Al(n,p)$\sp{27}$Mg were measured at T$\sb{\rm N}$ = 198 MeV using the Medium Resolution Spectrometer at Canada\u27s Tri-University Meson Facility in Vancouver, British Columbia. Multipole matrix elements were extracted in a macroscopic manner from the pion inelastic angular distributions using the distorted-wave impulse approximation and collective-model transition densities. Microscopic calculations of these extracted matrix elements and of the pion angular distributions were examined. Double charge exchange (DCX) excitation functions to the $\sp{27}$P ground state and an excited state were measured at nine incident pion energies from T$\sb\pi$ = 100 to 293.4 MeV. The systematics of DCX excitation functions to low-lying states is reviewed in light of these data. Microscopic calculations of DCX for and near A = 27 are investigated. Double giant resonances in $\sp{27}$P were observed at the three highest energies. The (n,p) charge exchange angular distributions were obtained for $\theta\sb{\rm lab.}$ = 0$\sp\circ$, 4$\sp\circ$, 8$\sp\circ$, 12$\sp\circ$, 18$\sp\circ$ and 24$\sp\circ$. The Gamow-Teller strength distribution was measured and compared to a microscopic calculation. The constant of proportionality between reduced transition probability and cross section (the unit cross section) was generalized and examined for configuration dependence. Data for higher spin-multipole isovector excitations are presented, including low-lying spin-isospin E2 strength and negative-parity giant resonances