Evidence for CoherentA2Production off Deuterium

We present evidence for coherent production of $A_2^{+}$ off deuterium at an incident ${\pi }^{+}$ momentum of 6.95 GeV/c. The data are taken from a 650 000-picture exposure of the 30-in. deuterium-filled MURA-ANL bubble chamber at Argonne National Laboratory. The $A_2$ signal is greatly enhanced by weighting the events with Zemach matrix elements for $2^{+}$ ${\rho }^0{\pi }^{+}$ decays. The cross section of 10 μb is well matched by a calculation using the cross section for production of the isoscalar $A_2$ off single nucleons and the deuterium form factor.