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nanoPHYS’12 – December 17-19, 2012. Construction of Drift Chambers for Drell -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.

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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