1. 2008-06-11Pierre-François Giraud, Muon Alignment Meeting1 Status of the barrel alignment system Pierre-François Giraud CERN

2. 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

3. 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

4. 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!

5. 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

6. 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

7. 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

8. 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

9. 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

10. 2008-06-11Pierre-François Giraud, Muon Alignment Meeting10 Alignment monitoring server Andrea Formica

11. 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

12. 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