Time spectra

The detailed understanding of the systematics of the -e time spectra is of utmost importance. There are several different ways to define these time spectra as summarized below. Of course, also combinations of these methods can be used.

definition	e definition
detected by beam telescope	external scintillators
tracked in TPC fiducial	MWPC
global/local pile-up free	MWPC tracking to stop
	tracking in TPC

Here we define as global pile-up free data (global-PU free) events which did not have another muon entering the TPC within T $_{PU} = \pm 15 \mu s$. We also can define the pile-up condition locally using the tracking capability of the detector. Local-PU free data are those where no other muon candidate stopped inside a cut volume around the reconstructed trajectory of the electron within $\pm T_{PU}$. Not surprisingly, selection of global-PU free muons and electron selection with external scintillators provide the most stable and robust results. When using the MWPC's, their thresholds have to be carefully tuned to avoid triggering on afterpulses and cross-talk from the large muon signals. The results of our second run indicate that careful electric layout and coincidence requirements between several chambers can reduce these effect to an acceptable level. Electron tracking in the TPC has the best vertex resolution, but large tail corrections.