1. nanoPHYS’12 – December 17-19, 2012 K. Nakano, S. Miyasaka, K. Nagai and S. Obata (Department of Physics, Tokyo Institute of Technology) Drift Chambers 1 2 cm Construction of New St. 3– Chamber Performance Requirements SeaQuest Spectrometer Summary & Plan Construction of Drift Chambers for Drell-Yan Measurement at FNAL SeaQuest For Details & Commissioning Status … Poster by F. Sanftl St. 3+ & St. 3– Chambers Structure – St. 3+ DC & New St. 3– DC New St. 3– chamber is being constructed at FNAL toward the physics run. Measuring Wire Tensions Stretching Wires Drift Property Detection Efficiency Hit distribution Procedures What’s Measured Muon pairs from Drell-Yan process Momentum ~ 30 GeV/c Solid Iron: Solid Iron: Focusing Magnet, Hadron absorber and beam dump Iron Wall: Hadron Absorber Station 1: Hodoscope array Wire chamber Station 4: Hodoscope array Prop. tube Station 2: Hodoscope array Wire chamber Liquid H 2, D 2 & solid targets Station 3: Hodoscope array Wire chamber KTeV magnet: Momentum meas. Proton beam 120 GeV Drell-Yan Process in Proton-Proton Reaction Front view Position & direction of sense wires 6 planes 14 o tilt in U & V Cell structure Guard wire Sense wire Field wire Cathode wire Muons Position resolution : 400 micron in 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 Operation Gas : Argon (86%) + Methane (10%) + CF4 (4%) HV : –2.4 kV (cathode & field), –1.4 kV (guard) Beam experiment for commissioning … March & April of 2012 Spectrometer upgrade … Now Beam experiment for physics … Spring of 2013 Experiment Schedule St. 3+ chamber has been tested With the commissioning beam With cosmic rays and a test chamber at Tokyo Tech 201202Constructed the frame parts @ Japan 03Transported the frame parts to Fermilab 06Assembled the frame 07-10Stretched all wires 11-12Build & attach the Mylar windows / Start gas flow 20131-2Build & attach the electronics for readout & HV / Start HV training 3Test 4 ?Start the physics run Measurement with the commissioning beam With & without hodoscope hits being 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 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% 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% (@ 3  ) achieved!! SeaQuest measures Drell-Yan process,, in proton-proton reaction with 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 SeaQuest Japanese group constructs & operates two drift chambers at Station 3 (St. 3+ & St. 3– ) Wire Sense : Au-W(Re),  30  m Others : Au-CuBe,  80  m Measurement with test chamber & Ar:CO 2 ( 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 layer has hit Efficiency ~ 100% within uncertainty at HV > 2.65 kV 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 Measurement with test chamber & Ar:CO 2 ( 80% : 20% ) Relation between drift distance & drift time Drift velocity ~ 30 micron/ns Consistent with Garfield simulation Position resolution = event-by-event drift-time deviation 500 micron Performance of St. 3+ Chamber 5 m × 5 m × 25 m