BaBar IFR Upgrade Mark Convery SLAC 7 Jun 06

BaBar Muon System History BaBar Instrumented Flux Return (IFR) designed to identify muons and neutral hadrons Originally consisted of iron absorber plates interleaved with Resistive Plate Chambers (RPC’s) Performance had been degrading since the start of BaBar in 1999 due to deteriorating performance of RPC’s Remediation has been in three steps Replacement of Forward Endcap with RPC’s in 2002 Replacement of two sextants of the Barrel with LST’s in 2004 Replacement of remaining four Barrel sextants planned for 2006 7 June 06 BaBar IFR Upgrade

Limited Streamer Tube Intro LST’s are simple and robust wire chambers Resistive cathode formed by extruded plastic comb coated with graphite Anode wire at 5.5kV Detectors mass-produced by existing Italian company Phi-position given by struck wire Z-position by signal induced on external strip plane 7 June 06 BaBar IFR Upgrade

2004 Installation Installation of 12 layers of LST’s and 6 layers of brass absorber Top and bottom sextants completed in ‘04 4 side sextants to be completed ‘06 QC during and after production, and after installation critical to good performance 7 June 06 BaBar IFR Upgrade

LST Occupancy Plots Online monitoring gives continuous check of electronics performance <0.5% dead channels 7 June 06 BaBar IFR Upgrade

LST Single Layer Efficiencies Offline monitoring of single layer efficiencies shows no degradation in performance in the first year of operation time time 7 June 06 BaBar IFR Upgrade

LST Operational Issues First two sextants of LST’s are “operational” and require very little operator intervention A few issues found (and fixed) in the first year of running: Flaky enable panel Bad Isobutane HV supply communication Leaky C02 dewar Total lost time<10 hours Mature BaBar experiement has very high standards! 7 June 06 BaBar IFR Upgrade

Muon-ID Performance Muon-ID perfomance in LST-sextants is now better than RPC’s were in 2000 Much better than current RPC performance 7 June 06 BaBar IFR Upgrade

2006 LST Detector Hardware In tests at SLAC In Italy All LST modules All Z-planes All HV supplies All HV cables Most of the manpower comes from collaborating institutions (students, post-docs) In Italy Front-end electronics Signal cables 7 June 06 BaBar IFR Upgrade

2006 Mechanical Installation Installation of side sextants will be more difficult than flat ones Large number of fixtures and procedures have been defined and tested 7 June 06 BaBar IFR Upgrade

2006 Installation Schedule Shutdown begins August 21 to coincide with LCLS and PEP-II work Re-start on January 5, 2007 Very tight schedule for LST installation Much effort going into planning and reducing required time Believe schedule is achievable, but very little schedule float 7 June 06 BaBar IFR Upgrade

Conclusion Success with first two sextants indicates that LST’s will “fix” the muon-ID problem and BaBar will have a well-performing muon system for the remaining data to be taken Very tight schedule for 2006 installation requires very careful planning to be successful 7 June 06 BaBar IFR Upgrade

7 June 06 BaBar IFR Upgrade