september 17th 2011, jps autumn meeting @ hirosaki university

Commissioning Status of the Drift Chamber for a Di-Muon Spectrometer at the E906/SeaQuest Experiment at

Fermilab

September 17th 2011, JPS autumn meeting @ Hirosaki University

東工大，理研 A ，高エネ機構 B ，山形大 C

Florian Sanftl ，後藤雄二 A ，澤田真也 B ，柴田利明，竹内信太郎，竹谷篤 A ，中野健一，宮坂翔，宮地義之

他 E906 / SeaQuest Collaboration

• SeaQuest: Physics Motivation• SeaQuest: Spectrometer• Drift Chamber(s): Design and Specifications• Experimental Setup @ Tokyo Tech• Results: Turn on curve• Track Reconstruction Algorithm • Results: XT-Curve• Conclusion

September 17th 2011 Florian Sanftl @ JPS autumn meeting 2011

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Outline

SeaQuest: Drell-Yan & Anti-Quarks in a Nutshell

Detector acceptance chooses xtarget and xbeam:

• Fixed target -> high xF = xbeam – xtarget

• Valence Beam quarks at high-x.• Sea Target quarks at low/intermediate-x.• Drell Yan as a perfect tool to probe Anti-Quarks

E906

Spect

.

Mon

te C

arlo

xtarget xbeam


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Sawada-san’s talk: 18pSL-6

Beam Energy:120 GeV / 800 GeV

SeaQuest: Spectrometer


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25m

Solid Iron

Focusing Magnet,

Hadron absorber

and beam dump

4.9m

Mom. Meas.

(KTeV Magnet)

Hadron Absorber

(Iron Wall)

Station 1:

Hodoscope array

MWDC tracking

Station 4:

Hodoscope array

Prop tube tracking

Liquid H2, d2, and solid

targets (e.g. Fe, Ca, C)

Station 2 and 3:

Hodoscope array

Drift Chamber tracking

Drawing: T. O’Connor and K. Bailey

Philosophy: Redo, Reuse, Recycle

St. 3Plus: NEW from E906J


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General Performance requirements• Detection Area:

1.6 m (vertical) x 2.2 m (horizontal)• 6 Active layers:

U/U’ (+14°), X/X’ (0°), V/V’ (-14°)• Position resolution: < 400 μm per planeGas Selection:• For now: Argon:CO2 (80:20)

The New Station 3 Drift Chamber(s)

U U’

VX

V’X’


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Cell Structure• Cell width & height 20 mm• Wire spacing 10 mm• Diameter sense wire (Au-W) 30 μm,

others (Au-CuBe) 80 μmPerformance Parameters• Gas-gain ~4.0E5• Drift velocity 3-6 cm / μsec (Ar:CO2)


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1.7 m

3.5 m

Test Chamber: Setup


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ASDQ card

Level Shifter Board

LVDSTo

NIMTDC

Stop

Coincidence

Start

Drift Chamber

Scinti. PMT Discri.

Scinti. + PMT Discri.

PC

Cosmic

• Read-Out Electronics same as SeaQuest• ASDQ = Amplifier, Signal Shaper, Discriminator &Charge Injector• Controlled by Level Shifter Board (Set thresholds, Ethernet access etc. pp.)• 48 Channels (= 6 x 8)• Coincidence as Trigger Start, Common Start Setup• Cosmic Rays are used no defined incident angle (range of ~10°)

0.7 m

1.7 m

Single Layer Detection Efficiencies


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Results:• The Single layer efficiency

increases with increasing High Voltage

• Single Layer efficiency reaches 95±5%@ -2.65kV

• Uncertainties are investigated (accidental coincidence)

• Discriminator Threshold on MAX

Some conclusions:• Some little space for

improvement• (Rough estimate for track

reconstruction eff. 74.4% for 5 hits minimum requirement)

Raw Data, TDC timings,

Mapping

T2X conversion

by GARFIELD

Tracking, 5 layer based

2-dim T-X-distribution

Tmeas vs. DCA

Project X distributions in all T bins

Extract new XT curve

Tracking: Algorithm


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Selections & definitions:• Drift time = TDC – t0

• Same t0 for all channels• Drift time window: 520ns• Accept event when

4 < Number of hits < 11per layer

Reconstructed track

Accepted Hits

Projected DCA

Deviation simulation/measurement:• Green bands is width of the projections• Those are constant over a wide T range• Band: Superposition of uncertainties from

hit reconstruction and track reconstruction• Disentanglement of both effects is

investigated

Tracking: Preliminary Results


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XT extraction:• 1st Iteration• Extracted curve agrees well with input

curve within uncertainties• Still too little statistics from the edge of

cell

Conclusions and Outlook


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• SeaQuest is a fixed target experiment at Fermilab• SeaQuest is going to measure the flavor asymmetry of the

nucleon sea• Commissioning is going to start in autumn 2011• The Japanese collaboration constructed and built a new DC• In order to prepare for the beam we setup the software package

based in our test chamber in Tokyo• We reported on the first extraction of an XT curve based on

cosmic data• The Tracking algorithm is working properly• We have to move forward a complete calibration• The uncertainties have to be better understood and investigated

Backup: Some Geometry


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X & X’

U & U’

edge

Sense wire

TDC data

Backup: TDC distributions


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350 ns

250 ns

Measured result Simulated result

• Observation• Discrepancy between

simulation and measurement• Account for that in the T2X

conversion

Backup: GasGain


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• The gas gain was • The gas gain increases when the HV value increases.• The measured results and the simulated results agree

in order of magnitude.• The measured value is about twice the simulated value.• The measured result shows the better gas gain in our

measurement.• The measured and the simulated results are consistent

within errors

Diameter of sense wire : 30 μm29.4 μm (): 110%28.5 μm (): 130%27.0 μm (): 180%26.5 μm (): 200%25.0 μm (): 290%

R : ±5% : ±15% ＋ 5% : ＋ 15% : ±10% : ±25% Density of gas : ±5% Diameter of sense wire (±10%) : ±80%

Total :

<Estimated change in gas gain>

< Systematic errors>

Note: The effect of the diameter of sense wires on the gas gain is large.

Backup: Tracking Algorithm v2


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• Cuts:• TDC Cuts• Number of events cuts• Sam t0 for all channels• 5 layers• … more Algo details

Raw Data, TDC timings

XT-input form GARFIELD

T2X conversion

Fit

New T2X curve

• Results:• Good agreement• More iterations• More data• Tracking efficiencies• Position resolution

september 17th 2011, jps autumn meeting @ hirosaki university

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