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

2. LC Workshop in Chicago, 20022 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

3. LC Workshop in Chicago, 20023 Resistive Plate Chambers HV Glass/Bakelite Gas Graphite MylarCopper For detailed information about RPCs consult http://www.coimbra.lip.pt/~rpc2001/talks.html General Design

4. LC Workshop in Chicago, 20024 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)

5. LC Workshop in Chicago, 20025 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

6. LC Workshop in Chicago, 20026 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