Vasiliki A. Mitsou CERN HEP 2003, 17-20 April, Athens, Greece

Construction and quality control of the end-cap Transition Radiation Tracker for the ATLAS experiment

Vasiliki A. MitsouCERN

HEP 2003, 17-20 April, Athens, Greece

18 Apr 2003 V. A. Mitsou / CERN 2

Outline

Introduction:ATLAS detectorTransition Radiation Tracker

Barrel modules productionEnd-cap wheels production

Acceptance tests at CERN

Gas tightnessWire tensionHigh voltageStraw straightness (WTS)

Status of electronicsConcluding remarks


ATLAS Inner Detector concept

General requirements:• Combination of

central tracker and TRD features

• Robust pattern recognition

• Bunch crossing rate – 40 MHz (25 ns between interactions)

• Interactions per year - 1016

• Selection level (Higgs) ~ 1:1013


Transition Radiation Tracker (TRT)

Length: Total 6802 cm

Barrel 148 cm

End-cap 257 cm

Outer diameter 206 cm

Inner diameter 96-128 cm

# straws: Total 372 832

Barrel 52 544

End-cap 319 488

# electronic channels 424 576

Weight ~ 1500 kg

Barrel

End-caps


TRT test-beam performance

Threshold: 200 eVDrift-time measurement efficiency within ±2.5 σ: 87%

Two thresholds: 0.2 keV and 5.5 keVFor 90% electron efficiency, 10-2 pion rejection


Barrel modules construction

Production of most of the parts (straws, radiator packs, wire supports, etc) is completed60 modules are completed so far (~60%)Barrel modules construction is expected to end by July 2003

Module testing is expected to end by August 2004Module gain mapper now operational


Module gain mapping

On-line fits, first scan

25 pulse-height spectra are taken along each wire


End-cap wheels production status

2 type-A, 4-plane wheels completed at PNPI (St. Petersburg)2 type-B, 4-plane wheels completed at JINR DubnaAll four wheels shipped to CERN – currently under testing13 (11) wheels partially assembled at PNPI (JINR) – absence of web circuitsType-C wheels (staged detector) not in production yet


1. Reception

2. Dimensional checks

3. Check of electrical connections

4. Gas tightness

5. Wire tension

6. HV (CO2)

7. Gas gain uniformity (WTS)

8. HV (Triple mixture)

9. 8- or 16-plane wheel assembly

10.Fluid tightness

11.Final dimensional checks

12.Repairs

Building 154at CERN:

Reception Acceptance Tests

AssemblyShort Term storage

Als

o a

t assem

bly

sit

es

Acceptance tests at CERN


P-regulator

Test: measurement of pressure loss inside the straws filled with Ar at 20 mbar overpressure

Specification: < 1 mbar/min/bar

Time: 1 day

INLETValve

P-gauge (room)Exhaust

Bubbler(26 cm Isopropyl alcohol)20 mbar max.

Ar cylinder

P-gauge (table)

RS-232

EXHAUSTValve

Interface box

PCI MIO16

4-plane wheel

T-sensorTable #2

RS-232

PC LABVIEWMainVI.vi

P-display

Gas tightness setup


Gas tightness results

Assembly site

CERN

20ITPNPA0001 0.05 0.04

20ITPNPA0002 0.28 0.195

20ITJNRB0001 0.04 0.15

20ITJNRB0003 0.04 0.08

20ITPNP000002

Spec: <1 mbar/min/bar


Wire tension: method

Method: mechanical resonance induced by a loudspeaker

Frequency scanning: [240,320] Hz

32 channels are scanned simultaneously

Spec: 55 < T < 80 g Slippage < 3 g

2r

2f Lμ4 gT


•No systematic wire slippage is observed

•Discrepancies between tension measured at CERN and assembly sites under investigation

•Wire tension setup is modified to obtain maximum reliability and efficiency

Wire tension: results


Test: 1800 V in CO2

Spec: current < 50 nA

The following circuits are checked, at different assembly and acceptance stages:

• Ground of WEB- high voltage socket

• Ground of ring - high voltage socket

• Neighboring high voltage sockets

HV socketGround

1 Flap in a WEB

HV Test (I)


Current (nA) distributionWheel 20ITPNPA00001

HV Test (II)

20ITPNPA0001

PNPI CERN

0 0

20ITPNPA0002

PNPI CERN

0 0

20ITJNRB0001

JINR CERN

0 -

20ITJNRA0003

JINR CERN

0 -

I > 50 nA


6 points of measurements along each straw

Slow control ( T, P, HV, humidity, gas flow)

Monitoring straws Electronics calibration Online/Offline analysis 4-plane wheel characterization

takes ~20 h at CERN

Measurement of gas gain (1% accuracy) to derive eccentricity value per straw

Gain variation:

Specification:

100% straws with G/G < 10% (400m)95% straws with G/G < 5% (300m)

)GG(21

minGmaxG

GG

61

Wheel Test Station (WTS)


PNPI Wheel #2 20ITPNPA000002

R1

R2

R3

R4

R5

R6

Straw 3407 Reference Straw

0.95

0.97

0.99

1.01

1.03

1.05

1.07

1.09

1.11

1.13

1.15

1 2 3 4 5 6

0.04

0.045

0.05

0.055

0.06

0.065

0.07

0.075

0.08

0.085

0.09

Mean

RMS G/G > 12 %

PNPI Wheel #1 20ITPNPA000001, straw 2/285

WTS: gain variation of one straw


95% strawsG/G = 5% 300 m

100% strawsG/G = 10% 400 m

Readout problems

PNPI Wheel #1 20ITPNPA000001

WTS: gain variation in one wheel (I)


Wire disconnection(400 μm)

20ITPNPA0001

20ITPNPA0002

20ITJNRA0003

1 0 4

Wire deviation > 400 μm:

WTS: gain variation in one wheel (II)


Gain variation (G/G):Max. error ~ ±

1%RMS < 0.5%

WTS results reproducibility


Electronics status

ASDBLR and DTMROC chips ready to start mass productionEnd-cap FE boards design almost finalized Barrel FE boards: new, more compact design with fewer connections adopted

ASDBLR boards DTMROC board


Production of TRT barrel models is well under way - 60% of the modules have been constructed so far

End-cap wheels of type A & B are being constructed and delivered to CERN since June 2002

Acceptance of first 4-plane wheels assembled at PNPI and JINR is successfully ongoing at CERN

No difference between characteristics of wheels (A &B) after assembly and after reception at CERN

Concluding remarks

Documents

Vasiliki A. Mitsou CERN HEP 2003, 17-20 April, Athens, Greece