Using the transmission method we have measured the circular polarization, $P_{\gamma }$, of $\gamma$ rays from excited projectilelike fragments in the reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ at 100 MeV. The polarizations are large with values up to $\left|P_{\gamma }\right|\cong 100$%. Over the whole $Q$ range, the sign and magnitude of $P_{\gamma }$ can be interpreted in terms of matching conditions familiar from direct-reaction analysis, contrasting the statistical character of the associated heavy-fragment excitation.

• Received 5 January 1981

DOI:https://doi.org/10.1103/PhysRevLett.46.1188