ATLAS Placement and Alignments. David Lissauer / BNL. Experimental Hall is very small compare to ATLAS Size. “Ship in a Bottle” Need to be aligned to the beam line to ~ mm and many of large Many envelopes have less than 20mm stay clear areasbetween moving Objects. Every Silly mm Counts!!!.
David Lissauer / BNL
Experimental Hall is very small compare to ATLAS Size.
“Ship in a Bottle”
Need to be aligned to the beam line to ~ mm and many of large Many envelopes have less than 20mm stay clear areasbetween moving Objects.
Every Silly mm Counts!!!
Result of many discussions over the past year with:
Survey Team. LHC Machine and Civil Engineering.
Toroid and Muon Placement. Calorimeters: LAr/Tile.
Inner Detector. Beam Pipe.
EC Toroid, Shielding
Items under active consideration:
Floor Stability -- Monitoring on going
HO/HS Structures -- Accepted
Feet & Rail Placement -- Feet Accepted/Final Rail Aug ’05.
Barrel Toroid Placement -- Ongoing
Barrel Calorimeters/Solenoid -- Ongoing
EC Calorimeter -- Under study
ID Placement -- Preliminary agreement/Ongoing
Beam Pipe Placement -- Preliminary agreement/Ongoing
Small Wheel -- Under Study
EC Toroid -- Under Study
Big Wheels -- Under Study
EO Chambers -- Under Study
JF Shielding -- Under Study
Uncertainty might be reduced by the time Barrel Calorimeter is installed (’05)
TC/Survey/Systems follow each of the “assemblies”
Working groups follow Placement specifications, and survey needs.
The existing calculation were done with simplifying assumptions.
~ + 1 mm / year due to hydrostatic pressure. Up To
~ 20 mm over 20 years.
A GRID of Survey “Rivets” has been installed at strategic position.
Monitoring of the floor stability is ongoing from July/August of ’03.
Expect to re-measure position every 2-6 month.
Accuracy : 0.3 mm – ‘datum point’: deep reference in the tunnel (same for machine and experiment geometry)
Hydrostatic System has been operating since June ’04.
(See TMB report by Hélène MAINAUD DURAND TS/SU/MTI)
Time span is small but measurements indicate movement of the floor. Higher on USA side than US side.
(For details see presentation by Jean-Christophe Gayde)
Relative height accuracy better than 100 Microns.
Absolute (relative to beam line 0.3 mm Sigma)
Floor Stability – 8/03 9/04.
Precision (1 sigma)of the dZ = 0.2 mm
From 25 June 04 to 08 Sept 04
Floor Movement uneven.
Possible combination of Hydrostatics lift and sage due to weight.
Need more time dependent data.
Due to Cement
Due to ATLAS
Summary of the “pessimistic” prediction for the floor movements.
Rail: Have been aligned and removed for Toroid installation.
Final alignment after Toroid is finished.
Feet : Have been placed in position.
All within Envelopes.
Bedplates: Have been placed in position.
Center of Toroid should co-inside with the Nominal Beam Line.
Assemble as Ellipse.
~20mm move due to Toroid weight.
~10 mm due to services and Muon chambers.
Position of First two Coils Fixes the center of the Toroid.
First Coils will fix the center of the Toroid.
Physics – Center of Toroid should be on the nominal beam line.
But can be as much as 20-30 mm off without affecting Muon trigger/Physics significantly.
Envelopes- require that the Toroid be within 10 mm envelope of nominal position.
We are more sensitive to down ward fluctuation than to Upward fluctuation.
place the Toroid Center at
– 5mm from Nominal Beam Line.
Final Decision Week of October 18th after latest input from Survey.
Cryostat IWV by ~ 4 mm.
Cryostat IWV by ~ 2 mm.
are now fixed and can not be changed.
Tile Calorimeter and Cryostat assembly is being done at Z=13.
After LAr if placed on the Tile on the Truck the relative position of the Tile/Cryostat IWV/Solenoid and EM position are fixed.
The Tile Calorimeter/Cryostat assembly will than be moved to Z=0.
The Barrel Calorimeter can be adjusted as a unit to the Nominal Beam line.
We will align the Solenoid Axis with relation to the nominal Beam Axis. Resulting in the above relative loactions.
SCT /TRT Axis is Collinear.
No Possibility for adjustments of SCT relative to TRT.
Pixel Tube can be inserted off axis by as much as 2-3 mm.
Once inserted they can not be adjusted.
The ID requires that the TRT/SCT axis co inside with the
IWV axis dues to the ID Services needs.
ATLAS thus agrees that the TRT/SCT Axis will be placed
2 mm off the nominal Beam Axis and off the Solenoid Axis.
The Present baseline is to install the Pixel to Co-inside
with the Nominal Beam Line
Reference plates for the alignment system
Reference points on the Toroid structure
Local reference frame of the small sector
Local reference frame of the large sector
Need to follow and re-optimize placement of detectors continuously.