The gamma ray ("Chang radiation") given out in the transition of a meson to the $1s$ ground state from a $2p$ orbit around a heavy nucleus of nonzero quadrupole moment is concluded to consist of several components of appreciable separation. Measurements of their energies should give information on (1) nuclear radius, (2) nuclear quadrupole moments, (3) the magnetic moment of the meson, (4) the nonuniformity of the nuclear charge distribution, and (5) nuclear polarizability and compressibility.

• Received 23 July 1953

DOI:https://doi.org/10.1103/PhysRev.92.812