The CMS Si-strip Tracker.pdf

a r X i v : p h y s i c s / 0 4 0 2 0 0 9 v 1 [ p h y s i c s .i n s - d e t ] 3 F e b 2 0 0 4 February 2, 2008 3:52 WSPC/Trim Size: 9in x 6in for Proceedings procs THE CMS SI-STRIP TRACKER G. SGUAZZONI? INFN Sezione di Pisa, I-56127, Pisa (PI), Italy E-mail: sguazzoni@pi.infn.it The CMS experiment at LHC features the largest Silicon Strip Tracker (SST) ever build. This device will be immersed in a 4T magnetic field in conjunction with a Pixel system allowing the momentum reconstruction of charged particles and the heavy-flavor tagging despite the hostile radiation environment. The impact of the operating conditions and the physics requirements on the SST layout and design choices is discussed and the expected performances are reviewed. 1. Requirements and Implications The Compact Muon Solenoid (CMS) experiment will observe pp collision at 14TeV of center-of-mass energy with a luminosity of 1034cm?2s?1. The bunch crossing frequency is 1/25ns = 40MHz and～ 20 minimum bias inter- actions per bunch crossing are expected, resulting in ～ 2000 charged tracks per event and a hadron flux up to 1014cm?2y?1 close to the interaction region. The physics requirements, a momentum resolution of ～ 1 ? 2%PT at ～ 100GeV/c and an impact parameter resolution of ～ 10? 20μm, have to be obtained by instrumenting a cylindrical volume of 5.4m in length and 2.4m in diameter immersed in a 4T axial magnetic field. The innermost region (r 15cm) is occupied by a pixel detector, described elsewhere1. The CMS collaboration decided to instrument the remaining volume by using only Silicon microstrip modules organized in 10 cylindrical layers and 12 disks as sketched in Figure 1, corresponding to more than 200m2 of active surface. A detailed description of the Silicon Strip Tracker (SST) and its expected performances can be found elsewhere2. Only a brief overview is given here. ?On behalf of the CMS Tracker Collaboration. 1 February 2, 2008 3:52 WSPC/Trim Size: 9in x 6in for Proceedings procs