Search for B/sup /. -->. B+. gamma. in UPSILON''' decays and the B/sup /-B mass difference

The CUSB detector at the Cornell Electron Storage Ring is used to measure the inclusive photon spectrum at the UPSILON''' peak at 10.58 GeV. In roughly-equal50 000 UPSILON''' decays, we do not observe any photon signal from B(..-->..B+..gamma.. decays for 20.. monochromatic ..gamma..+ hadrons of 6% to 9% at 90% confidence level. From the lack of a photon signal and the observed width of the UPSILON''' we deduce that the reconstructed b-flavored mesons from UPSILON''' are most likely the pseudoscalar B mesons and that the M(B()-M(B)> or =30 MeV.