Muon tracking

Due to their comparatively large energy depositions, muons are clearly seen and reconstructed in the TPC. Most crossing tracks can be disentangled. Small spurs on the muon tracks from $\delta$-electrons can be discriminated. Fig.12 presents an experimental study of a 2-dimensional stopping distribution of muons, selecting muons with a vertical cut of 2 cm at the TPC entrance. Since our prototype TPC is already well matched to the stopping range and divergence of the $\mu$E4 beam except in y-direction, the same dimensions in x and z and a y = 12 cm drifting space was chosen for the final chamber construction. This will reduce muon stops outside the sensitive TPC volume to 10%.

Figure 12: 2-dimensional muon stop distribution measured in 10 bar hydrogen gas. The beam enters horizontally from the left (z-direction, z = 30 cm). The charges drift vertically (y-direction, y = 8 cm).