Simulation and Measurement of the Fringe Field of the 1.5 Tesla BaBar Solenoid

摘要

In the context of the SLAC PEP-II asymmetric e{sup +}e{sup {minus}} collider and the BABAR detector with its 1.5 Tesla solenoid, we have calculated and measured the fringe field at the nearby beam elements and at the position of the photomultipliers external to the return iron but within a specially designed iron shield. The comparisons of these measurements with the simulations based on finite element analysis are remarkably good, within about 5 Gauss at the most critical beam element. The field at the photomultipliers is less than 1 Gauss, in agreement with the simulation. With a simple method of demagnetization of the shield, a maximum field of 0.6 Gauss is obtained.