Speaker
Description
The Mu2e experiment in Fermilab will search for the coherent neutrinoless conversion of a muon into an electron in the field of an aluminum nucleus, improving sensitivity by 4 orders of magnitude over existing limits and indirectly probing new physics beyond the reach of current or planned high energy colliders. To achieve a single conversion event sensitivity better than 3e-17, the experiment requires a high precision measurement of the ~105 MeV/c electron momentum while reducing to negligible all background contributions in the signal window. The primary detector element is a low-mass straw tracker chamber, comprising ~21,000 thin straw drift tubes of 5 mm diameter, arranged in a 3 m long cylinder of radius 700 mm, and operated in a magnetic field of 1 T and in vacuum. The tracker is designed to reconstruct the momentum of conversion electrons with a resolution of <180 keV/c. The distance of an electron track from the straw sense wire must be extracted within 200 μm from a TDC timing measurement, while time division yields the hit position along the straw within 3 cm. The straws are also instrumented with an ADC for dE/dx capability to separate electrons from highly ionizing protons. We will present the construction status and design of the tracker.
