The CMS Muon System BAN Yong Peking University

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

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

CMS Muon system: Introduction and status CMS Muon system: requirements 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… 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 Ge. V to a Te. V. • 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 BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status 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 ( 1 k Hz/cm 2) ● both endcap has 3 iron disks, and 4 layers divided into 2 or 3 stations. ● BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status CMS Muon system: trigger LHC luminosity: 1034 cm-2 s-1, ≈17 inelastic events/25 ns input rate of 109 /s should be reduced by 107 to 100 Hz (max. DAQ rate) CMS trigger: two levels • Level 1 (L 1): hardware trigger (DT, CSC, RPC) based on fast programable logic, here all data stored for 3. 2 μs, then no more than 100 k. Hz (50 k. Hz for the 1 st year) of the stored events are forwarded to the 2 nd level • High Level Trigger (HLT): software trigger based on commercial processors, single muon and di-muon selection algorithms BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status Extected muon trigger performences Efficiency of L 1 muon trigger to identify a single muon as a function of η Single muon trigger rate as a function of p. T threshold applied (at 1034 cm-2 s-1): Single muon rate ≈ 8 k. Hz at p. T threshold 2. 5 Ge. V (efficiency 90%); and ≈2. 8 k. Hz at 8. 5 Ge. V. BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status Extected muon reconstruction performences p. T resolution of muon tracks with or withour tracker matching Muon system standalone △p. T/p. T 8 – 15% 16 – 53 % reconstruction efficiency vs η muon system with tracker matching 0. 8 – 1. 5% 5 - 13% at 10 Ge. V at 1000 Ge. V BAN Yong __ IHEP Beijing -2006/12/12

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

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

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

CMS Muon system: Introduction and status RPC project at PKU: Cosmic ray test of the 1 st RPC prototype Conclusion: ÞThe Chinese RPC prototype has good mechanical strength, gas-tightness and HV performances; ÞThe efficiency and time resolution are satisfactory; ÞThe 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. BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status RPC project at PKU: Lab construction • 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 BAN Yong __ IHEP Beijing -2006/12/12

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

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

CMS Muon system: Introduction and status RPC project at PKU: Structure fabricated in China • readout strips fabricated by etching method • 5 mm Al Honeycomb core + 2 layers of 0. 5 mm thick Al sheets. • fill 5 mm thick Al plates at the edges, and in the position where there are slots, holes for screws etc. BAN Yong __ IHEP Beijing -2006/12/12

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

CMS Muon system: Introduction and status End-cap RPC Assembly and test at CERN-ISR 07/2004 – 11/2005 : all RE 1/2 and RE 1/3 RPC assembled the test results showed good efficiency and low dark current. efficiency cluster size BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status RPC project at PKU: installation started from 2005 , up to now 108 RPC RE 1/2 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 RE 1 RPC completed, the test commission were done, the results satisfying BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status CMS Muon system: status 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. BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status CMS Muon system: RPC efficiency at MTCC Efficiency evaluated by extrapolation of DT's segments to RPC modules. Local Efficiency at different High Voltage local efficiency Global efficiency HV=8. 5 k. V HV=9. 0 k. V HV=9. 2 k. V HV=9. 4 k. V HV=9. 6 k. V BAN Yong __ IHEP Beijing -2006/12/12 fg Opening Session CMS Week Dec 06 : Barrel MU

y CMS Muon system: Introduction and status CMS Muon system: f Compare MTCC Data and MC x Muon Stand. Alone p. T spectrum: (4 T) Data, Run 4181 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 BAN Yong __ IHEP Beijing -2006/12/12

CMS Muon system: Introduction and status CMS Muon system: Conclusions: 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 1 st collision of LHC. ● BAN Yong __ IHEP Beijing -2006/12/12