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2008-06-11Pierre-François Giraud, Muon Alignment Meeting1 Status of the barrel alignment system Pierre-François Giraud CERN
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting2 Status of the barrel optical system Most critical system: projective (PRO) #1 source of information for the alignment system Most difficult to put in operation Chambers that still need to be put in position: BIL6A01 BIL6A13 BIL6C13 BML5A13 BML6A13 BML5C13 BML6C13 Goal: 100% of PRO sensors and >99% total sensors Should be achieved soon Remanufacturing of 4 PRO extension plates underway Will also be needed for last 4 PRO extensions History of PRO sensors PRO sensor
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting3 Sector 05 reconstruction: AXI+PRA Fit chamber positions in sector 05 along with additional parameters that are meant to compensate incorrect gluing of the platforms or bad mounting of the sensors Compare with mechanical measurements available from Nikhef Ball is not in contact! Fit a rotation modeling sensor bad mounting Fit a translation modeling imprecise gluing along wire Without fit of rotation With fit of rotation Fitted rotation Bad news for the PRA+AXI system: a significant part of the sensors are badly mounted Mechanical measurements are an excellent debugging tool for the alignment Independent cross-check
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting4 REF calibrations and reconstruction Accuracy of REF system: <1mm at LED Magnification of longest REF lines: 1.5% Accuracy of positionning of elements on calibration bench should be 15 µm 1mm x 1.5% = 15 µm We expect it is not that good! Test the quality of calibration in data: Fit chamber positions using AXI+PRA+REF systems Compare distance between BI and BM with laser distance-meter measurements Measure the distance between BIL BML Compare to distance estimated with REF Residual not so bad in sector 05!
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting5 Improving REF calibrations Idea: use the distance-meter measurements in the fit, and fit additional degrees of freedom to account for a correction to the calibrations Additional degrees of freedom constraint at 30 µm Result: a new set of calibration constants for REF Residual to distance-meter measurement is included in the fit Residual is improved
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting6 LHCb PRO mag is averaged over ~120 measurements Comparison to distance-meter measurements Bug on PRO magnification Distance- meter between CL and between LM By design: Distance BIL-BML is constraint by REF (1 mm) Distance BML-BOL is then constraint by PRO mag (1 mm) Bug in rasnik analysis on magnification is reported by Krzysztof Syryczynski (LHCb) In ATLAS, we confirm the presence of a serious bug by comparing with distance-meter measurements This is a serious bug for the alignment system that needs to be fixed! For now: discard PRO mag (5-10 mm) in ASAP and use instead distance-meter measurements (<1 mm) Accuracy should be 1 mm
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting7 Fitting the full system in sector 05 Activated system: All MDT sector 05 reference plates sectors 04 and 06 All optical lines activated: PRA, AXI, REF and PRO Laser distance meter measurements are included in th fit Fit chamber positions, PRA platforms displacements and corrections to REF calibrations A lines are publicized and may be used for cosmic reconstruction (see talk by F. Chevallier). Expected accuracy 100- 200 µm PRO x residual RMS = 0.14 mm PRO y residual RMS = 0.24 mm
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting8 Measurements in the pit Measurements in the pit have proved to be extremely useful for debugging the optical system Mechanical measurements (Nikhef) Distance between BOS/BOL/BIL Difference of height between chambers Some measurements in other sectors are foreseen Distance-meter measurements (Saclay) Distance between PRO elements Distance between REF elements Measurements in (all?) other sectors are foreseen Other measurements are also foreseen: between layers of chambers Accuracy ~<100 µm Accuracy ~400 µm RPC MDT Special mechanic needed to access tubes behind RPC
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting9 Alignment monitoring server ๏ The alignment monitoring server is based on a 3-tiers model Information Service : the Oracle DB ‣ full structure of alignment related tables used for configuration and correction production Middle tier : J2EE Application Server (JBoss) ‣ core of the monitoring application: handle DB interactions and low level functionalities for querying ‣ Web application also deployed at this level Client tier : command line, web, GUI,.... ‣ access to AS application is possible via HTTP, CORBA-IIOP (RMI) from distant client applications Andrea Formica
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting10 Alignment monitoring server Andrea Formica
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting11 Jobs performed on the alignment server Sector 05 alignment: every 45 minutes A lines go into COOL and could be tested in the cosmics reconstruction REF system: every 20 minutes Not many movements are seen yet Will be used to monitor deformations of the toroid during the barrel magnet test starting this week Reconstructed positions of 4 of the REF plates No movement seen yet
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2008-06-11Pierre-François Giraud, Muon Alignment Meeting12 Conclusion Alignment system is very close to its final state 98% of total sensors are working Commissioning in sector 05 is well advanced With the help of additional measurements, commissioning in other sectors should start Development performed on the alignment server: ASAP reconstructions are performed online and written to the database REF will be used to monitor deformations of the toroid during magnet tests
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