BaBar LST Upgrade Mark Convery SLAC 13 Jun 07

BaBar IFR Instrumented Flux Return intended to ID muons and KL Barrel Composed of Barrel and Endcaps (forward and backward) Initially instrumented with plastic RPC’s in streamer mode 1 4 3 2 5 Barrel Endcaps 13 June 07 BaBar LST Upgrade

IFR Degradation RPC performance began degrading as soon as BaBar began taking data Many attempts at remediation, but degradation continued 13 June 07 BaBar LST Upgrade

IFR Upgrade Timeline Oct ‘00 - IFR flagged as major problem Summer ‘02 FWD Endcap RPC’s replaced Dec ‘02 decision taken to replace Barrel RPC’s with LST’s (12 layers) and brass absorber (6 layers) Summer ‘04 - First 2 sextants of LST’s installed Fall ‘06 (delayed from ‘05 by SLAC schedule) - Last 4 LST sextants installed New layer New RPC belt 10cm steel 5 layers of 2.5 cm brass 13 June 07 BaBar LST Upgrade

Limited Streamer Tubes LST’s are low cost plastic wire chambers with resistive cathodes Signals are induced on external cathode planes We use the the wire signal for phi and an external plane for z LST tubes made commercially in Italy and assembled into modules at OSU and Princeton Z-planes manufactured At SLAC, NIM A556, 134(2006) 13 June 07 BaBar LST Upgrade

LST Module QC Once modules are installed, they cannot be removed Exhaustive QC needed to ensure performance In Italy At Princeton, OSU At SLAC, before and after installation. Coordinated by C. Young and M. Convery All LST modules kept on gas and HV while being stored at SLAC Singles rate plateau curves taken 13 June 07 BaBar LST Upgrade

Fall ‘06 LST Installation Engineering Installation of 4 “side” sextants required a major intervention Removal of corner blocks EMC load transfer Brass absorber insertion Installing modules at an angle J. Krebs (SLAC) et al. Designed, built and tested 41 different below-the-hook fixtures 92 LST modules/sextant 13 June 07 BaBar LST Upgrade

LST HV Cable Installation LST’s have a huge HV cable plant - 600 multi-wire cables from EH to barrel Cables had to be in place before module installation could begin Coordinated by M. Convery and SLAC tecnhicians Grad student labor from UCI, UCR, UCSB, Notre Dame,Tennessee, South Carolina, UBC, McGill… 13 June 07 BaBar LST Upgrade

LST Module Staging The modules were prepared for installation one day in advance at CEH (P. Grenier, SLAC) This step was a limiting factor in ‘04. Not in ‘06, despite faster installation 13 June 07 BaBar LST Upgrade

LST Module Installation Installation days very tightly scheduled Transfer of LST”s from CEH to IR2 Module insertion Gas connection HV/signal cabling QC Best day installed 5 layers (35 modules) One module installed, while another waits on transfer frame 13 June 07 BaBar LST Upgrade

LST HV System 21 HV supplies provided by OSU monitor current on each LST tube 2007 performance has been superb 13 June 07 BaBar LST Upgrade

LST Gas System System for mixing, monitoring and distributing gas provided by SLAC (R. Messner) has worked perfectly 13 June 07 BaBar LST Upgrade

LST Electronics Checkout LST readout electronics provided by INFN (Ferrara) Pulse-test checkout during installation Plateau curves taken night of installation 13 June 07 BaBar LST Upgrade

LST Operations Online monitoring checked every run Dead wires: 18 out of 4656 Dead strips: 12 out of 5070 Layer Wire Efficiency check daily In ‘07, a single glitch due to gas problem LST system now managed by M. Convery (SLAC) and R. Calabrese (Ferarra) 13 June 07 BaBar LST Upgrade

Muon Efficiency Muon efficiency degradation reversed Performance For em = 90% Old p mis-ID=12% New p mis-ID=3% For p mis-ID = 2% Old em = 60% New em = 85% 13 June 07 BaBar LST Upgrade

Outlook LST is now a fully operational system with very smooth operation Careful monitoring is necessary to ensure continued excellent performance But, we don’t anticipate any further interventions before the end-of-BaBar NIM paper in preparation 13 June 07 BaBar LST Upgrade

Backup Slides 13 June 07 BaBar LST Upgrade

Sandwich Efficiency Ideally, we would measure efficiency at LiveFastMon level However, no tracks available, for “real”efficiency Can instead calculate “sandwich” efficiency Require hits in layer n and n+2 Look for hits in layer n+1 Eff. time G. Cibinetto 13 June 07 BaBar LST Upgrade

Sandwiches in LiveFastMon Sandwich algorithm implemented in LiveFastMon Efficiencies now monitored by DQM Inner layers have apparently lower efficiency due to hadronic showers that can miss layer n+1 Also plan to install a small LST module to test Isobutane E. Robutti 13 June 07 BaBar LST Upgrade

HV Trip Auto-reset During normal operation, we have typically one HV supply trip per day Caused by “Self-sustaining discharges” Previously, shifter either Resets the trip (hospital channels) Pages the LST ops manager Would like to reduce this workload for the shifter (and Ops manager) Auto-reset will reset trip 3 times within 15 minutes, before giving up and setting alarm Shifter then pages LST Ops manager So far, only used on “hospital” power supply. Will expand to other 6 supplies soon. 13 June 07 BaBar LST Upgrade

Auto-Reset Performance After trip Waits 30 seconds Ramps up Will try 3 times Shifter sees transient alarms If unsuccesful HV stays down Persistent alarm Shifter pages LST Ops manager 13 June 07 BaBar LST Upgrade G. Benelli

QC Test Results Plenty of modules passed HV testing Finishing singles rates this week Good Bad 13 June 07 BaBar LST Upgrade

2006 Mechanical Installation Installation of side sextants will be more difficult than flat ones 41 “below the hook” lifting fixtures and procedures have been defined and tested (J.Krebs) Motorized sloped platform 13 June 07 BaBar LST Upgrade

Mechanical Installation II EMC Load Transfer Brass Installation Fixture 13 June 07 BaBar LST Upgrade

LST Module/Z-plane Installation Some new features Sloped sectors 4 layers/day (x2 of ‘04) Very tight schedule during “installation days” Currently planned at 15 minute level Staging at CEH to keep ahead of IR2 needs Transfer frame W. Sands 13 June 07 BaBar LST Upgrade

Cabling HV Cabling Signal Cabling Separate HV wire for each LST wire Must be done before installation Signal Cabling Must be done in phase with module installation Cannot hold up installation 13 June 07 BaBar LST Upgrade

QC During Installation t=0 1 hour 2 hours Time Line Modules installation z signal cabling Long/short haul Gas line Front side connection Pulser test Final module positioning Signal cable routing HV cabling on PS N E W L A Y R Forward & backward backward forward forward G. Cibinetto 13 June 07 BaBar LST Upgrade