INTERFERENCE EFFECTS IN NONANALOG PION DOUBLE-CHARGE-EXCHANGE

For (pi+,pi-) double charge exchange on Al-27, an excitation function at 5-degrees has been measured over a range of incident pion energies from 100 to 293 MeV for transitions to both the ground state and to a doublet at 1.75 MeV of excitation in the final nucleus P-27. The shape s of these excitation functions are strikingly different, with the g.s . data exhibiting an interferencelike dip near 150 MeV and the excited state falling smoothly above 150 MeV.