Two-Photon Trigger Rate and Acceptance Studies

For stopped pions, the $\pi^-p\rightarrow\pi^0n$ reaction (B.R. $=$ 0.61) and $\pi^0\rightarrow\gamma\gamma$ decay (B.R. $=$ 0.99) yields photon-pairs with photon energies of 55-83 MeV and opening angles of 153-180$^{\circ}$. Using this two-photon calibration source the magnetic field and trigger condition dependence of the two-photon acceptance was studied from the data collected using the polyethylene target during the May-June, 1997 test run.