HCAL with Resistive Plate Chambers José Repond Argonne National Laboratory Presented at the Chicago Linear Collider Workshop January 7-9, 2002

LC Workshop in Chicago, Requirements for active material of HCAL Ability to finely segment: O (1cm 2 ) Works in magnetic field Fits in gap of < 8 mm Efficient (>95%) Reliable Affordable } All requirements met by RPCs

LC Workshop in Chicago, Resistive Plate Chambers HV Glass/Bakelite Gas Graphite MylarCopper For detailed information about RPCs consult General Design

LC Workshop in Chicago, Design Options Resistive Plates Mode of Operation Read-out Bakelite (Pseudo)-Analog Streamer Avalanche Digital Glass +faster recharging+lower HV (<9kV) +simplest +implement few thresholds 4 corresponds to 2 bits + no coating needed +faster O (1kHz/cm 2 ) +signal charge better defined +simple and sturdy - needs to be coated -somewhat slower -higher HV (~10kV) -slower O (100Hz/cm 2 ) -signal charge ill defined Response to 2 GeV electrons After ‘brick’ of 8 X 0 Taken from D.Auterio (OPERA)

LC Workshop in Chicago, Activities at Argonne I Ambats A Bamberger G Drake J Repond R Yoshida Built gas mixing system Using Tetrafluorethane 96.5% Isobutane 3.0% Sulfur Hexafluoride 0.5% Obtained 4 prototypes from FNAL Bamberger built 1 prototype at Freiburg Glass plates 0.3 mm gas gap 8 strips ganged together Starting test program Glass plates 2.1 mm gas gap 20x20cm 2 pick-up pad

LC Workshop in Chicago, Issues to be studied Measure and minimize noise versus efficiency Vary gas mixture, gap size, operating HV… Measure and minimize cross talk Develop front-end electronics Vary size of pick-up strips, gap between strips Exploiting experience with recently produced system for Straw Tube Tracker Test single particle resolutions Measure linearity Measure rate capability Test readout philosophies: digital vs. (pseudo)-analog Built small prototype calorimeter …Stay tuned