Measurement of Inverse Pion Photoproduction at Energies Spanning the   N(1440) Resonance
  Differential cross sections for the process pi^- p -> gamma n have been measured at Brookhaven National Laboratory's Alternating Gradient Synchrotron with the Crystal Ball multiphoton spectrometer. Measurements were made at 18 pion momenta from 238 to 748 MeV/c, corresponding to E_gamma for the inverse reaction from 285 to 769 MeV. The data have been used to evaluate the gamma n multipoles in the vicinity of the N(1440) resonance. We compare our data and multipoles to previous determinations. A new three-parameter SAID fit yields 36 +/- 7 (GeV)^-1/2 X 10^-3 for the A^n_1/2 amplitude of the P_11. 
A. Shafi, S. Prakhov, I.I. Strakovsky, W.J. Briscoe, B.M.K. Nefkens,   C.E. Allgower, R.A. Arndt, V. Bekrenev, C. Bennhold, ...