A Simplified Magnetic Field Tapering and Target Optimisation for the Neutrino Factory Capture System

In the Neutrino Factory, a 4 MW proton beam with a kinetic energy between 5 and 15 GeV interacts with a liquid mercury jet target in order to produce pions that will decay to muons, which in turn decay to neutrinos. The baseline-capturing layout consists of a series of solenoids producing a tapered magnetic field from 20 T, near the target, down to 1.5 T at the entrance of the drift section where the captured pions decay into muons to produce a useful beam for the machine. In our alternative layout the magnetic field is rapidly squeezed from 20 T to 1.5T using only three solenoids. This layout showed to produce similar performance, having the advantage being simpler and could potentially be made more robust to radiation. Here we report on further optimization studies taking into account the complete path and shape fluctuations of the Hg-jet.