Simulation of Pierre Auger Surface Detector Response to Muons

A. K. TRIPATHI; K. ARISAKA; D. BARNHILL; A. ETCHEGOYEN; A. FILEVICH; J. GONZALEZ; T. MCCAULEY; M. C. MEDINA; D. MELO; T. OHNUKI; T. PAUL; W. SLATER; D. SUPANITSKY; A. TAMASHIRO

Tsukuba - Japon

Conferencia; 28th International Cosmic Ray Conference; 2003

International Cosmic Ray Conference

We report the results of simulations of the Pierre Auger surface detector response to muons. The absolute energy scale in Auger surface detectors is characterized by the so called “Vertical Equivalent Muon” (VEM), which is the average energy deposited by vertical penetrating muons, going through the center of the tank. In reality, for practical reasons, we can only measure the energy deposited by omni-directional muons, triggering on simple coincidence among three PMTs in a detector. Such a trigger provides a characteristic peak in the total charge distribution (“muon hump”). The value of ”VEM” must be inferred from the “Muon Hump” location. This ratio of “muon hump” to VEM is determined from a few especially equipped tanks, and then applied to all the tanks in the array. As a result, any systematic effects in this ratio would propagate to the whole array. This makes it very important to fully understand the detector response to muons, as well as the “Muon Hump”/VEM ratio and any associated systematic by Monte Carlo. Our studies indicate that we can measure VEM to within 5% accuracy.