For high fluence, good S/N ratio thanks to: Single strip leakage current I leak  95nA at T  -5C Interstrip capacitance  3pF SVX4 chip 10 modules fully assembled: hybrids work well 2Electrical staves ALREADY build The new SVXIIb will be installed in 2006 (6 months shutdown) Silicon Sensors in High Luminosity environment Silicon detectors are damaged by radiation primarily through displacement of Silicon or impurities from the lattice. As a result the sensors are subjected to: increase in leakage current and thus in shot noise, heat,.. substrate-type inversion which affect the depletion voltage All  2300 sensors are n-type single- sided high resistivity bulk silicon microstrip detectors:  operating at high voltages (  350V), they are radiation hard  all SVXIIb detectors have intermediate strips yielding excellent resolution More sensors are required to maintain the same tracking capability (SVXIIa had double- side sensors that decrease the number of detectors used) Silicon is actively cooled down (L0&L1  -5C) to decrease the leakage current Irradiation damage Study: Neutron Irradiation performed at UC Davis: 7* MeV eq-n cm -2 & 1.4* MeV eq-n cm -2 Prototype sensors Detectors are manufactured by Hamamatsu Photonics: all un- irradiated prototyped sensors have been FULLY CHARACTERIZATED at Tsukuba, Purdue and UNM: Svx4 chip SVX4 is 0.25  m CMOS translation of SVX3D chip. Chips have been irradiated to 16Mrad with Co-60 facility and no change has been observed: enhanced radiation tolerance. The data plot is from the 1st module where the bonding for each chips was different: not bonded to anything, bonded to pitch adapter,bonded to PA and one sensor, bonded to PA and 2 sensors. As the capacitance increases you can see that the noise level increases as expected: signal/noise 30% better than SVX3 128-channel device; 8-bit digitization on chip, deadtime less, dynamical pedestal substraction,low power Stave design The new silicon detector Layer 0: 12 fold Axial Layer 1: 6 fold Axial-Axial Layer 2: 6 fold Axial-SAS(1.2  ) Layer 3: 12 fold SAS(1.2  )-Axial Layer 4: 16 fold SAS(1.2  )-Axial Layer 5: 20 fold Axial-Axial Layout The new detector SVXIIB has 6 layers with 2 barrels in z, each 66cm long. As in RunIIa, the staves within a layer are arranged in a castellated patter. The RunIIa portcards have been removed from the tracking volume to minimize the mass Improvements  extension of the “contained b-jets” region  more uniform radial distribution A stave, the RunIIA ladder, is a structural element with 6 axial sensors on one side and 6 axial or small angle stereo sensors on the other side. The two sides are separated by a few mm. The key feature of the RunIIb design is the uniform stave design for 90% of the sensors L1-L5: 180 staves can be produced with the same mechanical fixture (SVXIIa has 180 ladders, 5 sizes and 36 of each size) L0 is similar to RunIIa L00: axial sensor at small radius, small strip pitch and with very low mass Schematic of a stave: 1 bus cable, 6 sensors, 3 hybrids, 4 chips on each hybrid (2 chip for beam pipe layer) Improvements  layout easy to mass produce  L0 will guarantee a good impact parameter resolution for unshared hits  L1 strengthens the pattern recognition near the beam pipe (redundancy of the axial layers ensures a good axial hit)  L5 strengthens the connection to the COT  Loss in z-resolution but better hits-tracks association Impact parameter resolution in r-  for all axial sensors Impact parameter resolution in r-z for all stereo sensors The average material for the RunIIa and RunIIb silicon detector designs is compared for normal incidence trajectories as a function of position along beam line Less material than in RunIIa due to compact stave structure and progress in hybrid technology The plots show the b-tagging efficiency vs b-jet (studies performed using RunIIa simulation) and the Higgs mass sensitivity as a function of b-tag efficiency  (  is relative to 65%) SENSORS The new Silicon detector at RunIIb Configuration  d (  m) Asymptotic  d (  m) P t =2GeV All layers625 NO L NO L0951 NO L0 or L11579 Configuration  z (  m) Asymptotic  z (  m) P t =2GeV L2-L5 + 1 ISL1.4 L2-L4 + 1 ISL1.8 L2-L5 only1.4 L2-L4 only2.0 PartsSVXIIaSVXIIb Hybrids101 Sensors52 Ladders51 Layer R (cm)Calcul. Dose RunIIb *10 13 (1 MeV eq-n cm -2 )