Wolfgang Menges, Queen Mary The BaBar Muon System Upgrade Wolfgang Menges Queen Mary, University of London On behalf of the BaBar LST Group

Wolfgang Menges, Queen Mary The BaBar LST Group M. Andreotti, D. Bettoni, R. Calabrese, V. Carassiti, G. Cibinetto, A. Cotta Ramusino, N. Gagliardi, M. Negrini, L. Piemontese, V. Santoro Universita di Ferrara and INFN P. Patteri Laboratori Nazionali di Frascati dell’INFN R. Capra, M. Lo Vetere, S. Minutoli, P. Musico, E. Robutti, S. Tosi Universita di Genova and INFN C. Simani, D. Lange, C-S Cheng Lawrence Livermore National Laboratory Y. Zheng Massachusetts Institute of Technology T. Allmendinger, G. Benelli, M. Gee, L. Corwin, K.Honscheid, R. Kass, R. King, J. Regensburger, C. Rush, S. Smith, Q. Wong Ohio State University C. Fanin, M. Morandin, M. Posocco, M. Rotondo, R. Stroili Universita di Padova and INFN R. Covarelli Universita di Perugia and INFN W. Menges Queen Mary, University of London J. Biesiada, G-L. Cavoto, N. Danielson, R. Fernholz, Y. Lau, C. Lu, J. Olsen, W. Sands, A.J.S. Smith, A. Telnov Princeton University B. Fulsom University of British Columbia T. M. Hong University of California at Santa Babara S. Chen, J. Zhang University of Colorado D. Warner Colorado State University P.Trapani Torino M. Lu, N. Sinev, J. Strube University of Oregon S. Morganti, G Piredda, C. Voena Universita di Roma La Sapienza and INFN H.P. Paar University of California at San Diego R. Boyce, M. R. Convery, P. Kim, J. Krebs, R. Messner, M. Olson, R. Schindler, S. Swain, T. Weber, W. Wisniewski, C. Young Stanford Linear Accelerator Center

Wolfgang Menges, Queen Mary The BaBar Detector Problems with RPCs: -> upgrade forward system -> replace barrel system with Limited Streamer Tubes Single Layer Efficiency: Initial technology for muon system was Resistive Plate Chambers.

Wolfgang Menges, Queen Mary The BaBar Muon System Problems with RPCs: -> upgrade forward system -> replace barrel system with2002 project start Limited Streamer Tubes st installation phase nd installation phase Forward System Backward System Barrel System 12layers of detector 6layers of brass 1layer not used

Wolfgang Menges, Queen Mary LSTs were choosen as replacement: -> robust and simple technology -> time / resource constraints -> successful history (SLD, ZEUS, LEP experiments) Limited Streamer Tubes Main components:  coordinate -> tube z coordinate -> z-plane Other components: gas system HV system signal readout Physical principle is simple: -> single wire in a cell (gas filled, on HV) -> charged particle ionises gas -> streamer build up

Wolfgang Menges, Queen Mary Limited Streamer Tubes tubes consist of 7 or 8 cells cell dimensions: 15 mm x 17mm x ~4m consists of gold-plated anode wire and graphite-painted PVC walls (cathode) enclosed in PVC sleeve endcaps include HV / gas connections 4 signal channels per tube 15 mm

Wolfgang Menges, Queen Mary Z-planes Solder joints need monitoring before and after installation. (a few broken joints) Vacuum laminated Mylar planes: -> 35 mm wide copper strips -> 2 mm wide gaps -> 96 channels bundled to 6 cables Solder joints ~3.8m ~4m Flat cables for signal readout

Wolfgang Menges, Queen Mary Quality Control Rigorous QC is mandatory at all production stages for an excellent performance of the detector! QC station at SLAC 1275 tubes under long term testing for 2 nd installation

Wolfgang Menges, Queen Mary Quality Control: Scan Test Quality Tests: resistance capacitance gas leaks source scan HV conditioning singles rates scan tube with radioactive source tube current should be ~1  A repair or reject failed tubes (open tube in clean room) Continuous discharge Source removed 6 wire holder

Wolfgang Menges, Queen Mary Quality Tests: resistance capacitance gas leaks Source scan HV conditioning singles rates Burn-in Process Quality Control: HV Operation at 5500V Plateau HV (V) Counts/100s 3000

Wolfgang Menges, Queen Mary Installation Summer empty layers z-planes tubes 12 layers of LSTs 6 layers of brass

Wolfgang Menges, Queen Mary Gas System Gas Mixture: CO 2 /Ar/Isobutane 89% / 3% / 8% Digital Bubbler Design goals: non flammable good quenching properties -> no secondary streamers Gas Mixer Mass Flow Controllers

Wolfgang Menges, Queen Mary HV System Custom-built power supplies: operation range: 0V V over-current protections starts at ~3  A, protection circuit per channel four independent groups a 20 channels, each HV channel split into 4 pins -> 4000 HV cables 7 PS installed Custom-built HV cables: 24 km of multi-conductor Kerpen cable two parts: (custom-inline connector) –short-haul at tube –long-haul at power supply Design goal: high granularity easy access

Wolfgang Menges, Queen Mary Front End Electronics New front end electronics have been developed: common mother board for wires and strips different daughter boards for signal -> simple components Front end cards are located in near vicinity of the BaBar detector. Signals are amplified, discriminated and put into the BaBar DAQ system. 4 daughter boards Mother board Analog inDigital out Strips Wire Raw Signals

Wolfgang Menges, Queen Mary Data Taking Run 5 Run 5 started March > 60 fb -1 collected until Oct 05 -> 250 fb -1 expected by summer 05

Wolfgang Menges, Queen Mary Wires for lower sextant Monitoring: Wires and Strips Installed LST tubes: -> 388 tubes phi channels -> excellent performance -> monthly testing with Single Rates -> problems with 5 channels < 0.4 % Installed Z-planes: -> 24 Z-planes strip channels -> 5 dead strips < 0.3% -> bad solder joints Running since October 2004! Layer Strips for upper sextant Channel. Dead strip

Wolfgang Menges, Queen Mary Efficiency Average wire efficiency Average strip efficiency Time average efficiency per layer ~90% geometrical efficiency 92.5% wire and strip performance excellent efficiency stable over time Time

Wolfgang Menges, Queen Mary RPCs LSTs Impact on Physics Use muon selection for performance check: neural network based selector -> first year with LSTs is better performing than first year with RPCs

Wolfgang Menges, Queen Mary Summary The installation in summer 2004 was a success ! the installed components are working well –> 99.6% of the wire channels are working –> 99.7% of the z-strips are working –muon selection efficiency is better than ever quality control is essential for this –Tubes: source scan, HV conditioning, singles rate –Z-planes: capacitance measurement tubes and z-planes ready for 2 nd Phase of installation in 2006