Transcript Monitored Drift Tubes

Como, 8/10/03
ATLAS Muon Chamber construction in Greece
and
alignment studies for H  ZZ  4μ decay
Christine KOURKOUMELIS
University of Athens
ATLAS: Muon Chambers
Each detector has 3 stations.
Each station consists of 2-4 layers.
M
D
T
M
D
T
Precision
chambers
CS
T C
G
C
RP
C
Trigger
chambers
Monitored Drift Tubes ( |η| < 2 )
with a single wire resolution of 80 μm
1194 chambers, 5500m2
GREECE constructs 13%
Cathode Strip Chambers (2 < |η| < 2.7)
at higher particle fluxes
32 chambers, 27 m2
Resistive Plate Chambers (|η| < 1.05)
with a good time resolution of 1 ns
1136 chambers, 3650 m2
Thin Gap Chambers (1.05 < |η| < 2.4)
at higher particle fluxes
1584 chambers, 2900 m2
ATLAS MUON SPECTROMETER
(View of non-trigger chambers)
: MDTs
Monitored Drift Tubes
width (tube length) : 83-494 cm
length : 90-216 cm
Tube : Al, 30 mm φ, 0.4 mm wall
Wire : 50 μm, W/Re alloy (97/3)
Gas : Ar/CO2 (93%/7%) at 3 bar
Gas gain : 2x104 at 3080 V
Maximum drift time : ~ 700 ns
Resolution : 80 μm
Construction requirements/specifications
for MDT tubes
Anode Wire Mechanical Tension (350 gf  5% )
High Voltage Leak Current (<2nA/meter)
Gas Leak Rate (<2*10-2 bar*lit/sec)
Anode Wire Position ( 25 μm)
To comply with the above : precision tooling, clean rooms,
intense QA/QC tests, etc.. @ all three institutions
University of Athens : Muon tube wiring facility
(http://www.phys.uoa.gr/Atlas/MDT)
University of Athens : Muon tube wiring facility
University of Athens : Muon tube wiring facility
Wire insertion –
wire tensioning
Wire threading- wire tensioning
Tube production quality checks
Finished tube length
Wiring tension
DRIFT TUBE PRODUCTION IN THE UoA
WORKING CONTINOUSLY SINCE Sept. 2000
STEADY
PRODUCTION OF
42 tubes/day
NTUniversity of Athens : Muon tube testing facility
Anode Wire Mechanical Tension measurement
T =   D2 L2 f 2
.
Nominal Value
• L= 165 cm is the wire length
• D= 50 μm is the wire diameter
ρ = 19.3 gr/cm3 is the density of the
wire material
NTUniversity of Athens : Muon tube testing facility
High Voltage Leak Current measurement
• A bunch of 16 tubes is connected in parallel
and supplied by the gas mixture Ar:CO2 (93:7)
at 3 bar absolute pressure and high tension of
3400 V.
•The voltage drop across a resistor of 1.1 MΩ
in series with the tubes is being measured for
each tube.
Leak Current < 2nA/m
NTUniversity of Athens : Muon tube testing facility
Gas Leak Rate measurement
• The idea is to fill the tubes with the detector gas (Ar:93 %, CO2:7 %) and then measure the
pressure drop due to gas leakage at the time interval t.
• V is the volume of the "leaking" tube and
• Δp is the pressure drop.
Anode Wire Position measurement
University of Thessaloniki : Muon chamber assembly facility
University of Thessaloniki : Muon chamber assembly facility
Height adjustment of layers
Relative position controlled to +-10μm
Rasnik tower
results for
80 chambers
BIS quality tests @ CERN (1
chamber –out of 12
construction sites -to meet construction requirements)
st
X-RAY TOMOGRAPHY
April-01 11.7 ÷ 13.9 µm
July-00 11.0 ÷ 16.2 µm
The results meet
the ATLAS
specifications !!!
BIS tests @ CERN’s-testbeams
X5/GIF
2002
BIS tests @ home institutions
UoA cosmic rays set-up
AUTh cosmic rays set-up
BIS chamber construction in Greece
Greece (112 BIS)
140
120
No. Chambers
100
Bare MDT
Plan Bare MDT
MDT with FC
Plan MDT with FC
Final MDT
Plan Final MDT
Ready for Installation MS
28-10-04
80
60
40
20
0
Jan-00
Jan-01
Jan-02
Time
Jan-03
Jan-04
Jan-05
Has been going extremely well for 3 years-will finish soon !
SUMMARY
Bare chambers production expected to finish by next April
Meanwhile:
•Equip the chambers with services ( gas, electronics..)
•Test EVERY chamber with cosmic rays
•BE READY FOR INSTALLATION at the pit by Aug.2004
(Olympic games)- 150 chambers
BIS chamber integration-services
Cosmic ray set-up to test several chambers
simultaneously
90 chambers are already constructed, should be
equipped and tested
Muon Chamber alignment for
Higgs studies
Aim of the study
 Estimate how muon chamber
misalignments
influence Higgs reconstruction into 4 muons,
H  ZZ  4μ , its mass resolution and the number of
accepted events.
Study how can the possible shifts be discovered and
estimated from the data.
12
10
8
6
Barrel projective alignment
4
2
End-cap pseudo-projective alignment
 Global End-Cap translation
I. Longitudinal trans. (named displ z)
II. Transverse translation (named displ T)
(0, 1, 3 and 5 mm)
 Global End-Cap rotation
I. Rotation around beam axis (named rotat z)
I.
Rotation around transverse to the beam axis (named
rotat T) (0, 2.5, 5 and 10 mrad)
Only one end-cap was misaligned
(the other was kept unchanged- for reference)
The effect of 5 mm longitudinal displacement of one
end-cap for the reconstructed Higgs
mH=200 GeV
mH=300 GeV
The relative increase of the width of the reconstructed
200 GeV Higgs
Translations
Rotations
The relative decrease in the acceptance of
the reconstructed 200 GeV Higgs candidates
Translations
Rotations
Influence of end-cap rotations on Z’s
(at least one μ in rotated end-cap)
Effect is big and
can easily be
spotted!!
The increase of the width of the reconstructed
Z’s (when one muon is in the misaligned end-cap)
Translations
Rotations
Conclusions:
The misalignments effects
we studied :
•can be spotted from their
effect on the Z width
and corrected for
• will not influence the
Higgs potential for the
specific channel more
than a few percent
SM Higgs Potential: 3 YRS @ LOW LUMINOSITY