Heidt, Christopher, 28 May 2012 19:38

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MICE beam line and measurement of emittance

The International Muon Ionization Cooling Experiment (MICE) is designed to demonstrate the currently untested technique of ionization cooling. Theoretically, this process can condition the high quality muon beams required to build a Neutrino Factory or Muon Collider. The beam line to transport muons into the MICE cooling channel lattice cell was installed in December 2009. Step~I of the experimental programme, whose goal was to demonstrate that the beam line can generate beams similar to those expected in a Neutrino Factory cooling channel, was completed recently.

Methods have been developed to use time-difference measurements in the MICE time-of-flight counters (TOFs) to obtain a transverse spatial resolution of approximately $10\unit{mm}$ and to track muons through the focussing elements of the beam line, thus allowing the trace-space vectors of individual muons to be reconstructed and their integrated path length to be calculated. The TOFs were used to make an absolute measurement of the momentum of muons with zero bias and a systematic error of less than $3\unit{MeV/c}$.

The measured trace-space vectors of single muons were used to estimate the emittances and approximate optical parameters of eighteen muon beams. The results of beam line simulations were compared with the measurements and, once the effects of experimental resolution had had been included, found to be in good agreement. A sample of individual muons whose phase space vectors had been measured was injected into a simulation of the full MICE cooling channel; the beam was found to be suitable for demonstrating muon cooling, although some fine-tuning of the cooling channel optics will eventually be required.