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RPC Update. What’s new since September…. Jos é Repond Argonne National Laboratory. American Working Group On Linear Collider Calorimetry 24 November 2003. Outline. • New chamber construction • New gas • Multi-channel VME boards • HV system • Prototype system
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RPC Update What’s new since September… José Repond Argonne National Laboratory American Working Group On Linear Collider Calorimetry 24 November 2003
Outline • New chamber construction • New gas • Multi-channel VME boards • HV system • Prototype system • Plans for the next few months
Chamber construction Argonne built 3 chambers early in 2003 2-gas gap chamber - extensive tests with single pads - extensive tests with multi-pads - geometrical tests Now built one more Single-gas gap chamber - first tests: same efficiency higher charge - tests with multi-pads needed: ‘cross-talk’?
New Gas In the past used mostly Freon:Argon:Isobutane = 62:30:8 Now using new gas Freon:Isobutane:SF6= 94.5:5:0.5 - Higher charge: <Q> ~ 1pC - Wider HV plateau without streamers
Large avalanche signal up to ~1.5 pC Mild streamer signal
Setting threshold Threshold of 400 pC possible with >95% efficiency Expect excellent noise suppression
Multi-channel VME readout 6U x 160 VME board VME64 compliant Contains 64 discriminators Optional amplification Records time-stamps of hits and hit patterns Commissioning Card can be read out! Front-end works for streamer signals (~10 pC) More work needed to provide enough amplification for avalanche mode
High Voltage System Being developed at ANL Based on ZEUS BCAL HV bases Cockcroft-Walton technology Cheaper than Bertran Prototypes Built and tested with RPCs For avalanche mode: need external filters Able to get σnoise to 10 fC
Prototype section: 1m3 Mechanical design Working on layout Electronic readout Ready for specification of FE ASIC Initiated discussions with FNAL In discussions with CALICE concerning back end
Application of graphite layer Workable paint in hand Encouraging results with silk screening Prototype section Design larger chambers, specify ASIC Geometrical efficiencies Investigate effect of HV leads and spacers Multi-channel VME readout Develop a useable FE for avalanche mode Measurements Multipad: efficiencies, noise rate, cross-talk… Plans for the next few months