Post on 13-Jan-2016
description
transcript
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
18 Apr 2003 V. A. Mitsou / CERN 3
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
18 Apr 2003 V. A. Mitsou / CERN 4
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
18 Apr 2003 V. A. Mitsou / CERN 5
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
18 Apr 2003 V. A. Mitsou / CERN 6
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
18 Apr 2003 V. A. Mitsou / CERN 7
Module gain mapping
On-line fits, first scan
25 pulse-height spectra are taken along each wire
18 Apr 2003 V. A. Mitsou / CERN 8
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
18 Apr 2003 V. A. Mitsou / CERN 9
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
18 Apr 2003 V. A. Mitsou / CERN 10
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
18 Apr 2003 V. A. Mitsou / CERN 11
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
18 Apr 2003 V. A. Mitsou / CERN 12
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
18 Apr 2003 V. A. Mitsou / CERN 13
•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
18 Apr 2003 V. A. Mitsou / CERN 14
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)
18 Apr 2003 V. A. Mitsou / CERN 15
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
18 Apr 2003 V. A. Mitsou / CERN 16
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)
18 Apr 2003 V. A. Mitsou / CERN 17
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
18 Apr 2003 V. A. Mitsou / CERN 18
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)
18 Apr 2003 V. A. Mitsou / CERN 19
Wire disconnection(400 μm)
20ITPNPA0001
20ITPNPA0002
20ITJNRA0003
1 0 4
Wire deviation > 400 μm:
WTS: gain variation in one wheel (II)
18 Apr 2003 V. A. Mitsou / CERN 20
Gain variation (G/G):Max. error ~ ±
1%RMS < 0.5%
WTS results reproducibility
18 Apr 2003 V. A. Mitsou / CERN 21
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
18 Apr 2003 V. A. Mitsou / CERN 22
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