Synchrotron Radiation Effects in the IR Solenoid Flux Excluder(LCC-0007)

We examine the emittance dilution due to synchrotron radiation in the fringing fields at the end of the ''flux excluder'' solenoid which protects the final doublet quadrupoles from the main detector solenoid field, and also the effect of SR in the main solenoid field itself.Because the deflection due to the excluder fringe field is opposite in polarity from that of the main solenoid, the resulting dispersive rays cancel at the IP; as a result the synchrotron radiation from the two magnetic fields produces only a small dilution of the vertical spot size. The contribution to the spot size from the finite opening angle of the synchrotron flux is found to be comparable to the contribution from solenoidal dispersion, and both are acceptable. We conclude that SR considerations do not rule out use of a flux excluder, and that the range of crossing angles and solenoidal fields available is large.