1. Commissioning of the MUON Spectrometers in ATLAS and CMS
Differences and similarities between the MUON Spectrometer of ATLAS and CMS.
Status of the ATLAS-MUON installation and Commissioning.
Status of the CMS-MUON installation and Commissioning.
General comments on readiness.
Conclusions.

2. Different Philosophies between the 2 large experiments
ATLAS Philosophy
Trigger and perform precise measurements of HE muons in the spectrometer, correct for losses in the calorimeters and improve measurement using inner detector for LE muons.
Main emphasis on low mass Spectrometer and high coverage (eta<2.7)
CMS Philosophy
Main emphasis of the spectrometer is on the trigger (2 different and complementary systems), while momentum measurement is mainly based on ID tracking in a high magnetic field (4 Tesla).
Main emphasis is on precise Pt measurements for rapidity <1.8.

3. Different Philosophies lead also to different importance of the ID measurement, and of the rapidity behavior
ATLAS
CMS
While in ATLAS, the MUON Spectrometer determines the P resolution for P>20GeV/c, in CMS the resolution is dominated by the ID.
In ATLAS, the MUON Spectrometer resolution is dominated by the alignment and the Drift Tubes resolution

4. Due to the magnetic field, the 2 experiments measure different things: ATLAS=P, CMS=Pt
In the low rapidity region CMS has a superior P resolution (mainly due to the high Solenoidal field), while at high rapidity, is the ATLAS spectrometer, with its toroidal field that has the better resolution.
At high momenta, it is the L**2 in BL**2 in the MUON Spectrometers,that allows to recuperate the P resolution.
Due to the relative importance of the MUON Spectrometer in ATLAS, its performance depend critically on:
Alignment
Good field knowledge (due to non-uniformity)
Good Drift Tubes Calibration

5. Status of the ATLAS-MUON installation and Commissioning
All barrel chambers have been installed, but not all are at the final position.
Except for 40% of the EO chambers to be installed in May, all End-Cap chambers have been installed.
The so called staged EE chambers have been constructed (thanks to Protvino) and their installation is foreseen after the shut-down.

6. Know the magnetic field; i. e
Know the magnetic field; i.e. know where the magnets are to within a couple of mm in a non-uniform field
Magnet was powered in November 06 and its field measured and reconstructed with probes installed in the chambers.

7. 4 coils were reconstructed in shape with very small residuals
If you know (alignment) where the chambers are, the field reconstruction works.

8. Where are the chambers and how much do they deform
6,000 images in the barrel and 6,000 in the end-caps.
System allows to measure:
Translations in X-Y
Rotation
magnification

9. Status of the barrel alignment and its Performance
Type
Total
Working
Broken
Bad because
MDT not in place
Projective
117 85 12 20
Axial
1035
998 10 27
Praxial
2006
1938 6 56
Reference
256
232 4
CCC
260
234 16
BIR/BIM 32
Inplane
2110
2064 8 38
5816
5589 50
177
Measuring 10 to 100 micron changes, due to magnet heaters being turned-on.

10. Status of End-Cap Alignment
Main reference system is the alignment bars.
Since Wheels are not in final longitudinal place, no projective element has been used, however they have been used to align and follow the chambers in the azimuthal component in the Small and Big Wheels.

11. Operation of the End-Cap Alignment
The alignment system has been used to correct the psition of the chambers in the Small and Big MUON Wheels.
All its elements (except the projective part) are working and the chamber positions are being monitored continuosly

12. Status of Barrel MDT Commissioning
Sectors from 3 to 8 Commissioned with Cosmic rays.
Sectors 1-2 & 9-10 noise test (missing HV-PS’s).
Sectors under test.
List of remaining problems
% Dead tubes less than 1‰
Some noisy wires mainly on BOS
# HV trips: 2
# Gas leaks: 18 yet unfixed leaks

13. Status of MDT-DCS Commissioning
HV/LV +monitoring of FE electronics T and V .
Alignment
Gas
B-field
T-sensors
Initialization

14. Status of MDT Commissioning in the End-Caps
Side C
LV+HV completed
Temporary Gas connections: now moving to final
Operated under Cosmic rays in common runs.
3 Chambers excluded from read-out for DAQ/Fiber problems
3 Multilayers with HV Problems
Side A
LV fully equipped
HV bottom half
Temporary Gas connections on bottom half: now moving to final
Bottom half operated under Cosmic rays in common runs.
1 FE card excluded from read-out
3% of all chambers with some problem: need access between wheels to solve them.

15. Status of MDT-CSC Commissioning in the End Caps: Small Wheels
Small Wheels fully commissioned outside pit.
All 3 systems have ~0.05% of non-working channels.
Transport through CERN has been very impressive.
No broken wires and no gas leaks after descend to ATLAS pit.
Second Wheel went down last Friday.

16. Installation and Commissioning of the EO-MDT chambers
All EOS chambers have been installed and commissioning has started.
9 out of the 16 mechanical Large sectors have been installed, with the corresponding alignment bars (major effort to have all components at CERN in mid December).
4 out of 16 Large sectors have been installed with all their chambers.
Following ATLAS closing, remaining 7 mechanical Large sectors to be installed (2 per day) and the remaining 12 chamber sectors (1 sector per day).
There will be very little time for commissioning of the large sectors.

17. Read out of MDT and Calibration
All ROD’s have been installed and tested.
Data taking is performed from the control room.
During December run, calibration data stream has become operational at LV2 (only data in ROI send to TIER2 centers).
Calibration performed quasi on-line, with very encouraging results.
Many problems, but first results are very encouraging.

18. Status of RPC Commissioning
Cabling of HV/LV Racks on HS
75% of the work completed
Missing Sectors 11, 12, 13, 14
Should be finished within 1 month (depending on CAEN delivery)
Cable test and connection to Chambers
Sectors 1-8 completely cabled
Working on 9 and 10
Work pace: 2 Weeks/sector
Will increase having a second team working in parallel

19. Status of RPC Commissioning
Many gas leaks found due to broken gas inlets (80, 43 of them already repaired).
All commissioning performed with gas circulating in open mode. Soon to move to recycle mode, but various issues need yet to be clarified.
To complete RPC commissioning by mid June, a 2 step procedure has been started, with the first step being:
Testing all cable connections and their correspondence checked
DCS working and electronic threshold optimization
HV checked and debugged
Gas Checked and debugged
Trigger electronics and front end electronics debugged and timed.
The remaining problems are left to a second pass.
With this procedure, expect to achieve 1 sector/2 weeks.

20. Status of RPC Commissioning
Sectors 1-6 have been commissioned with cosmics, while 7-8 are being completed now.
The number of problems left is small:
Dead strips= 0.2%
Disconnected gaps for HV problems 0.6%
Disconnected gaps for Gas Leak 0.2%
Noisy channels: few units
Average Noise 0.4 Hz/cm2
MDT -RPC Correlation
 ~ 9 mm
Distance between MDT
track and RPC cluster

21. Status of TGC Commissioning
All sectors tested with cosmics either in surface or in the pit: Bad Channels ≈ 10-4
6/24 sectors operated during common runs
CAEN Power supply and crates delivery have been the main bottleneck
Installing mini-crates and AC/DC converters
Difficult access for TGC3: Need BW away from EO for ½ of the sectors (2 Weeks of work in parallel with EO installation).
TGC currently operated with CO2 in a temporary Gas distribution System - Need urgently to move to Final Gas System:
Distribution racks (final connection to racks being performed now)
Final mixture (n-pentane): problems have been found with the heaters used to performed the mixture. Expect to be solved in April. A C

22. Status of TGC Commissioning
Both trigger and readout paths are operational.
All readout and trigger electronics are installed.
Trigger Latency measured: clk
C09
Previous
Current
Next
32/30132
events

23. Remaining problems
Although the CAEN delivery problem is under control (last delivery in April), there are still some problems with failure rates.
Cruising speed to commission the RPC system should be increased (doubled) in order to complete the first pass by end of May.
One needs to move soon to a gas recirculation system for RPC’s, and in particular optimize the various filters.
One needs to start the commissioning of the TGC gas system with CO2 and ensure that the final system will be available in May.
The available time to complete the power supplies installation for the Low-Pt trigger in the TGC’s (TGC2-3) is very tight (2 weeks in parallel to EO installation).
The time for the completion of the EOL installation is very tight (2 weeks), which will not allow much time for full commissioning.

24. The CMS muon system Barrel: Drift Tubes (DT) (4 layers)
Resistive Plate Chambers (RPC) (6 layers)
End caps: Cathode Strip Chambers (CSC) (4 layers)
Resistive Plate Chambers (RPC) (4 layers)

25. CMS muon detectors DT
CSC
RPC

26. Barrel wheel

27. End cap disks with CSC’s
22 Jan 08

28. A Measurement ! Magnet Test and Cosmic Challenge
MTCC: on the Surface
Cosmic muons momentum distribution)
MTCC: on the Surface
Cosmic muons charge ratio (+/-)
(Awaiting definitive alignment constants)

29. Commissioning DT system in UX
YB0
Entrance Angles

30. Examples of Performance: DT
Analysis of Drift-Tube commissioning data for Wheel 0, sector 10. Resolution ~ 300m from cosmic muons

31. Airshower triggered by RPC: DT segments reconstructed at HLT
November Global Run
100% of HB
50% of HF, HE
20% of DT, HO
10% of barrel RPC, EB (for a few days)
0.04% of strip tracker (6 module RIB prototype)
Synchronized
10M events logged
Small % of End-Caps detectors took part underground, due to Power Supplies delivery
Airshower triggered by RPC: DT segments reconstructed at HLT

32. General Comments on readiness
Both MUON systems have been delayed in their commissioning by the late arrival of CAEN Power Supplies, which should be completed by May-08.
In the case of ATLAS, being the MUON’s the outermost detector, their installation and their services were always the last one.
The RPC gas recirculation system has encountered many problems, not all yet solved, which have slow down the commissioning due to the high cost of gas.

33. Conclusions
The MUON systems of the 2 large LHC experiments, with 1,000’s of M**2 detectors and over 1M readout channels each, to measure the passage of the particles with resolutions of less than 100microns, constitute one of the major technological defies ever achieved.
The two experiments are well advanced in their commissioning aspects, and the fact that one is already taking cosmic data from their respective control room, a few months before beam is a very good sign.
Albeit many problems, the two large LHC experiments will be able to take MUON data with a large part of their systems at the beginning of the LHC beam.