1. The CMS Muon System BAN Yong, Peking University 2006/12/12 IHEP, Beijing, China Outline: CMS-Muon system: introduction China’s contribution to CMS Muon system Current status

2. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 CMS Muon system: introduction 3 different technologies: Drift Tube (DT) (barrel), Cathode strip chamber (CSC) (endcap) Resistive Plate Chambers (RPC) (barrel and endcap)

3. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 CMS Muon system: requirements Muon system: => excellent trigger, identification and reconstruction performance Muon trigger: excellent performance on single and multi-muons events and an unambiguous id of bunch crossing, combining RPC (fast time resolution) and DT, CSC (good spatial resolution) Redundancy in trigger and reconstruction: 2 technologies in whole angular region Good muon momemtum and charge measurement: muon possibly measured twice, in the tracker (inside 4 T field) and in the muon system, in the whole η region and from a few GeV to a TeV. Muon ID: to achieve very high efficiency (>95%) up to η =2.4 Robustness: operate well with a strong magnetic field and high radiation and interaction background At LHC: very high collision rate and low cross section for “new physics” very large background rate electrons and muons reconstruction are crucial in physics study…

4. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 CMS Muon system: layout CMS Muon system contains: 250 DTs, 540 CSCs and 912 RPCs, cover 0 < | η| < 2.4 Barrel region (0 < |η| < 1.2 ): ● magnetic field is low and almost uniform, muon rate is about 1 Hz/cm 2 (neutron induced background 1-10 Hz/cm 2 ) ● 5 wheels, each divided in 12 sectors with 4 iron gaps. muon station: one DT and two RPS chambers joint together Endcap region ( 0.9 < |η| < 2.4 ): ● magnetic field is strong (up to 3.5 T) and not uniform, gamma and neutron induced backgrounds are high ( 1k Hz/cm 2 ) ● both endcap has 3 iron disks, and 4 layers divided into 2 or 3 stations.

5. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 CMS Muon system: trigger CMS trigger: two levels Level 1 (L1): hardware trigger (DT, CSC, RPC) based on fast programable logic, here all data stored for 3.2 μs, then no more than 100 kHz (50 kHz for the 1st year) of the stored events are forwarded to the 2nd level High Level Trigger (HLT): software trigger based on commercial processors, single muon and di-muon selection algorithms LHC luminosity: 10 34 cm -2 s -1, ≈17 inelastic events/25 ns  input rate of 10 9 /s should be reduced by 10 7 to 100Hz (max. DAQ rate)

6. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 Extected muon trigger performences Single muon trigger rate as a function of p T threshold applied (at 10 34 cm -2 s -1 ) : Single muon rate ≈ 8kHz at p T threshold 2.5 GeV (efficiency 90%); and ≈2.8 kHz at 8.5GeV. Efficiency of L1 muon trigger to identify a single muon as a function of η

7. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 Extected muon reconstruction performences p T resolution of muon tracks with or withour reconstruction efficiency vs η tracker matching Muon system standalone muon system with tracker matching △ p T /p T 8 – 15% 0.8 – 1.5% at 10 GeV 16 – 53 % 5 - 13% at 1000GeV

8. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 CMS Muon system: China’s contribution Achievable MoU deliverables ( M. Della Negra, Beijing, 10/042003) Cost to completion: additional deliverables

9. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 RPC project at PKU: detector study  To understand the characteristics and the technical details of the RPC detector, before we really start on the CMS-RPC project.  Using Chinese material to build a RPC: collaborated with the factory to fabricate resistive plate (bakelite + melamine).  Two crucial characteristics affect the detector property: Resistivity and surface smoothness.

10. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 RPC project at PKU: Cosmic ray test of the 1st RPC prototype The RPC prototype was being tested by cosmic rays:  3 layers of scintillator construct the cosmic-ray telescope.  s small percentage of SF 6 killed the streamer signal. cosmic rays trigger. avalance signal Streamer signal

11. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 Conclusion:  The Chinese RPC prototype has good mechanical strength,gas-tightness and HV performances;  The efficiency and time resolution are satisfactory;  The efficiency at very high irradiation is limited due to the high resistivity of the bakelite. The PKU-RPC group accumulated experience and technical know-how of RPC. RPC project at PKU: Cosmic ray test of the 1st RPC prototype

12. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 Workshop of 140 m 2 area Gas and HV system, DAQ system Cosmic ray test stand: 10 slidable layers, can test 6-8 RPC simultaneously Clean room Crane, various tooling RPC project at PKU: Lab construction

13. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 RPC project at PKU: endcap “thin” chamber design RE1/2 “thin” chamber design.  Thickness of RE1/2,1/3: 28mm(chamber)+20mm(Front End Elec.)  Simple structure: mainly composed of 2 honeycomb plates + 4 Al frames+ front patch panel;  relatively easy for fabrication, assembly and maintenance.

14. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 RPC project at PKU: Beam test at GIF 2002 It’s the first full size “thin” designed chamber; first chamber with Chinese honeycomb mechanics.  Test results: the chamber has good gas-tightness, HV and efficiency performances. Our chamber at Building-40 for the exposition during autumn CMS-Week after successful beam test. Beam test at GIF

15. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 RPC project at PKU: Structure fabricated in China 5mm Al Honeycomb core + 2 layers of 0.5mm thick Al sheets. fill 5mm thick Al plates at the edges, and in the position where there are slots, holes for screws etc. readout strips fabricated by etching method

16. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 End-cap RPC Assembly and test at CERN-ISR

17. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12  07/2004 – 11/2005 : all RE1/2 and RE1/3 RPC assembled  the test results showed good efficiency and low dark current. efficiency cluster size End-cap RPC Assembly and test at CERN-ISR

18. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 RPC project at PKU: installation  installation started from 2005,up to now 108 RPC RE1/2 1/3 have been installed (3/4 of total of our task). The last batch of 36 RPCs will be installed in Jan. 2007  the connection and cabling of gas, cooling and HV, LV, DCS and signal cables for all installed RE1 RPC completed, the test commission were done, the results satisfying

19. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 The Magnet Test Cosmic Challenge (MTCC), for all CMS community, costituted a fundamental test-bed in order to check the detector performance in the final configuration. Whole slices of CMS apparatus have been tested using cosmic muons, taking a considerable data quantity during the period since July up to October. 3 barrel sector RPC and 1 endcap sector RPC were successfully operated. CMS Muon system: status

20. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 Local Efficiency at different High Voltage HV=8.5kV HV=9.0kV HV=9.2kV HV=9.4kV HV=9.6kV Global efficiency Efficiency evaluated by extrapolation of DT's segments to RPC modules. fg Opening Session CMS Week Dec 06 : Barrel MU CMS Muon system: RPC efficiency at MTCC local efficiency

21. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 Data, Run 4181 Muon StandAlone p T spectrum: (4 T) x y  CMS PHI from MC and measured with tracks Offline analyis of the test data is still ongoing. fg Opening Session CMS Week Dec 06 : Barrel MU CMS Muon system: Compare MTCC Data and MC Compare MTCC Data and MC

22. CMS Muon system: Introduction and status BAN Yong __ IHEP Beijing -2006/12/12 ● 3 different technologies (DT, CSC, RPC) (2 different muon detectors at any angular region) give CMS good muon trigger performance, and redundancy in trigger and reconstruction. ● Muon possibly measured twice in the tracker and in the muon system assure CMS a Good muon momemtum and charge measurement. ● The muon system were tested successfully during the MTCC. RPC Trigger System was successfully operated. The study of detector performance has given results according to the expectancy. ● Chinese institutions (IHEP and PKU) have sucefully fulfilled the related tasks in CMS muon system construction according to the CMS schedule. ● Still a lot of jobs on both hardware and software of CMS muon system to be done before the 1st collision of LHC. CMS Muon system: Conclusions: