ISOBAR ELECTROPRODUCTION AS A BACKGROUND FROM INTERACTION OF BEAMS WITH RESIDUAL-GAS AT PHI-FACTORIES

It is shown that when beams interact with a residual gas at phi-factor ies the reaction of the electroproduction of the Delta(1232) isobar pr oceeds vigorously. The isobar decay gives similar to 10(7) pions over an effective year of 10(7) s per meter of a residual gas. These pions are emitted largely across the beam axis with a resonance energy distr ibution at 265 MeV with a width 120 MeV in the isobar rest system. We present formulae for the distributions of the four-momentum transfer s quare, the angles, the energies and the momentum of the decay products , needed for the simulation of the process under consideration. (C) 19 97 Published by Elsevier Science B.V.