nanoPHYS’12 – December 17-19, 2012

1. nanoPHYS’12 – December 17-19, 2012 Construction of Drift Chambers forDrell-Yan Measurement at FNAL SeaQuest K. Nakano, S. Miyasaka, K. Nagai and S. Obata (Department of Physics, Tokyo Institute of Technology) SeaQuest Spectrometer Drell-Yan Process in Proton-Proton Reaction Iron Wall: Hadron Absorber What’s Measured • Muon pairs from Drell-Yan process • Momentum ~30 GeV/c Solid Iron:Focusing Magnet, Hadron absorber and beam dump KTeV magnet: Momentum meas. Station 4: Hodoscope array Prop. tube Proton beam 120 GeV Station 3: Hodoscope array Wire chamber Experiment Schedule Station 2: Hodoscope array Wire chamber • Beam experiment for commissioning … March & April of 2012 • Spectrometer upgrade … Now • Beam experiment for physics … Spring of 2013 Station 1: Hodoscope array Wire chamber Liquid H2, D2 & solid targets 5 m × 5 m × 25 m For Details & Commissioning Status … Poster by F. Sanftl Drift Chambers Structure – St. 3+ DC & New St. 3– DC St. 3+ & St. 3– Chambers • Front view • Cell structure SeaQuestJapanesegroupconstructs & operates two drift chambers at Station 3 (St. 3+ & St. 3– ) Guard wire Muons Performance Requirements Sense wire • Position resolution : 400 micronin horizon direction • Muons are bent in horizontal plane • Rate tolerance : upto 1 kHz in wire length of 1 mm • Backgrounds due to muons from J/psi decay>> Drell-Yan signals Field wire Cathode wire • Position & direction of sense wires • 6 planes • 14o tilt in U & V Operation 2 cm • Gas : Argon (86%) + Methane (10%) + CF4 (4%) • HV : –2.4 kV (cathode & field), –1.4 kV (guard) 2 cm • Wire • Sense : Au-W(Re), f30 mm • Others : Au-CuBe, f80 mm Performance of St. 3+ Chamber Construction of New St. 3– Chamber New St. 3– chamber is being constructed at FNAL toward the physics run. • St. 3+ chamber has been tested • With the commissioning beam • With cosmic rays and a test chamber at Tokyo Tech Procedures Drift Property • Measurement with test chamber & Ar:CO2 ( 80% : 20% ) • Relation between drift distance & drift time • Drift velocity ~ 30 micron/ns • Consistent with Garfield simulation • Position resolution = event-by-event drift-time deviation500 micron Detection Efficiency Stretching Wires • Measurement with test chamber & Ar:CO2 ( 80% : 20% ) • Definition: efficiency of detecting one track by one plane • Track coincidence of two scintillators covering 10 cm (5 wires) × 18 cm • Efficient event one (or more) of wires in layerhas hit • Efficiency ~ 100% within uncertainty at HV > 2.65 kV • 5,154 wires … 768 of sense wires & 4386 of other wires • Optimized procedure • 2 minutes/wire • 4 hour/shift x 2 shifts/day x 2 months • Tension of wires • Adjusted by a metal block hanged • 75 gf for sense wires & 130 gf for other wires • Accuracy: 10% required & 5% (@ 3s) achieved!! Hit distribution • Measurement with the commissioning beam • With & without hodoscope hitsbeing matched • GEANT4 simulation • Several mass ranges … J/psi, D-Y near J/psi, D-Y w/ high mass, etc. • To be compared with measurement • Dimuons from Drell-Yan, J/psi, Upsilons Measuring Wire Tensions • Measure the eigen frequency () of wire free oscillation • External pulse w/ initiates the oscillation • Oscillation is detected as induced voltage • Amplitude gets maximum @ • Derive tension ( ) from by • Accuracy: 0.5% Summary & Plan • Spectrometer is being upgraded now for higher beam rate (× 10) in physics run • Detectors … St. 1 & St. 3– chambers • Beam … monitor & intensity stabilizer • Data acquisition … fast throughput • A beam experiment for physics will start in Spring of 2013 • SeaQuest measures Drell-Yan process, , in proton-proton reactionwith 120 GeV proton beam at FNAL • SeaQueast Japanese group constructs & operates two drift chambers at Station 3 (St. 3+, St. 3– ) • The detail of the chamber characteristics are shown above • St. 3+ chamber has been tested with the commissioning beam and with cosmic rays and test chamber at Tokyo Tech • New St.3– chamber is being constructed at FNAL toward the physics run