Discussion of the Muon Peaks

The muon peak spectra were taken by triggering on the paddle signals. It so happens that the paddle set above igloo 1 has only one good signal. Thus we have two main trigger modes using the paddles: 2-fold coincidences, using both signals from the paddle set below the igloo, and 3-fold coincidences, using the two signals from below and the one signal from above the igloo.

We have taken data using both types of paddle trigger. The 2-fold coincidence has a much higher rate and is a more convenient measurement to use. It is also a slightly broader peak, since there is a wider range of possible paths that a through-going muon can take and still trigger the experiment. This means that there is a wider range in the number of Cherenkov photons produced by the muon, and therefore a wider range in the number of PEs.

The 3-fold coincidence spectra have narrower muon peaks, due to the more restricted paths available to through-going muons.