IFR Past, Present, &Future ( 1 month access zLimited tests were carried out during accesses or on a few chambers yLowered barrel temp. to 17 C. yReversed HV yIncreased gas flow yLowered discriminator threshold yPut weights over inefficient regions zNo effect zGas composition was regularly tested yNo evidence of water vapor A wide spread of plateau curves were measured. Nov. 14, 2002 Henry Band - U. of Wisconsin 33 RPC tests at Frascati, 1997 zHV modules shipped to LNF. zLongitudinal strips were applied. zModules packed into boxes zCosmic ray tests were made to characterize each module zGas Ar 45%, Freon 50%, isobutane 5% AA Hz Nov. 14, 2002 Henry Band - U. of Wisconsin 34 RPC radiography The RPC efficiency was mapped in 2D showing irregular regions of reduced efficiency. D. Piccolo Nov. 14, 2002 Henry Band - U. of Wisconsin 35 IFR Construction Quality Quality distribution vs production box Fraction of good chambers not uniformly distibuted in time Production problems? I. Peruzzi Nov. 14, 2002 Henry Band - U. of Wisconsin 36 The shifting plateau problem: a plateau collection Nov. 14, 2002 Henry Band - U. of Wisconsin 37 Efficiency - LNF Efficiency of barrel modules 10 11 Nov. 14, 2002 Henry Band - U. of Wisconsin 38 BABAR RPC zOperates in limited streamer mode zParallel high resitivity plates (Bakelite cm ) zGraphite ~100 k / zAccording to the General Tecnica factory the RPCs were filled 3 times with a mixture of 70% linseed oil and 30% n- pentane. Air was then flushed through the RPC for several days. zStrip pitch yBarrel mm ( ), 38 mm (z) yEndcap 26 mm(y), 38 mm (x) zChanges from L3 RPCs yPolycarbonate buttons with lip replaced G10 cylindrical button ySingle layer with strips on both sides yNo mechanical envelope yNonflammable gas - low iso- butane %, CBrF 3 replaced by Freon 134a C 2 H 2 F 4 z Gas mixture in % Nov. 14, 2002 Henry Band - U. of Wisconsin 39 IFR History zRPCs chosen for BaBar 1/95 yMature technology yGood L3 experience zRPC Production 7/96- 10/97 zRPC QA tests - Frascati y I 95% zChamber assembly SLAC 12/ /97 zChamber tests at SLAC 5/97 12/97 yInitial tests xHigh Temperatures - 30 C xHigh Currents ~100 A xEfficiency > 95% yAssembly/test area air conditioned 7/97 zChamber insertion 6/97 -12/97 zCabling and Fecs installed from 10/97 zComplete Barrel and Forward E.C. 11/98 zBarrel cosmic ray tests 12/98 zSharply increasing current observed when doors closed and LV on z Backward E.C. completed 4 / 99 z First beam May 99 z99% of RPCs working z96% of Fecs working z Heating from electronics & ambient hall raise steel T to z HV current limitations force reduction in # of RPCs z A barrel ~70 Endcap z Complete barrel cooling 10/99 z Install Endcap cooling 1/00 - 4/00 z 60 A barrel ~40 Endcap z Average Efficiency remain ~85% Nov. 14, 2002 Henry Band - U. of Wisconsin 40 RPC Efficiencies Nov. 14, 2002 Henry Band - U. of Wisconsin 41 RPC Efficiencies Nov. 14, 2002 Henry Band - U. of Wisconsin 42 RPC Efficiencies Nov. 14, 2002 Henry Band - U. of Wisconsin 43 Radiographies 1010 Nov. 14, 2002 Henry Band - U. of Wisconsin 44 Radiographies for the 24 new modules 1010