Analysis of DHCAL Muon Data

This note reports preliminary results of the large CALICE Digital Hadron Calorimeter prototype (DHCAL) from beam tests with muons. The DHCAL consists of 38 layers instrumented with Resistive Plate Chambers (RPCs) and interleaved with 2 cm thick steel absorber plates. The prototype was tested in October 2010 and January 2011 in the Fermilab FTBF test beam. In the January run part of the Tail Catcher and Muon Tracker (TCMT), located behind the DHCAL, was also instrumented with RPCs. In the final configuration the system counted 51 $1 \times 1$ m$^2$ layers and over 470,000 readout channels. The response to muons is utilized to align the various layers of the calorimeter, to scan the response across a single pad, to measure the efficiency and pad multiplicity, and last but not least to establish the calibration constants for each RPC in the stack. The response is simulated with GEANT4 and a standalone program, RPCSIM, emulating the RPC response. The various parameters of the RPCSIM program are tuned to reproduce the measured performance of the detector.