25/9/2006Dmitri Tsybychev Stony Brook1 Vertex 2006 Perugia, Italy September 24-29, 2006 DØ Silicon Detector and Experience at Tevatron D. Tsybychev (Stony Brook) On behalf of DØ collaboration

25/9/2006 Dmitri Tsybychev Stony Brook 2 Outline: Overview of Tevatron and DØ experiment Layer 0 concept Layer 0 commissioning and preliminary performance SMT status Summary and outlook

25/9/2006 Dmitri Tsybychev Stony Brook 3 The Tevatron Proton-Antiproton collider √s = 1.96 GeV Ultimate peak luminosity 3x10 32 cm -2 s -1 Expecting to accumulate 8 fb -1 by 2009 Good data taking efficiency ~ 85%

25/9/2006 Dmitri Tsybychev Stony Brook 4 DØ Detector Central Scintillator Forward Mini- drift chamb’s Forward Scint Shielding Tracking: Solenoid(2T), Silicon, Fiber Tracker Calorimeter Central PDTs

5 SMT Design cm 6 barrels 12 F-disks 4 H-disks 4 super-layers in barrel L1in, L3in: DSDM, 90 o stereo L1out, L3out: single sided L2, L4: DS, 2 o stereo

6 DØ Layer 0 Mitigates tracking losses due to radiation damage to Layer 1 of SMT detector Improve IP resolution, especially for low p T tracks Less material at first silicon hit 1 st Tracking hit closer to IP Layer-0 Physics Gains Proper Time Resolution   = 105 fs (SMT)  75 fs (layer-0, no layer-1) b-Tagging efficiency gain ~15%

25/9/2006 Dmitri Tsybychev Stony Brook 7 Where does L0 go? Very tight space constraint outer radius ~23mm inner radius ~15mm

25/9/2006 Dmitri Tsybychev Stony Brook 8 Layer 0 installed inside SMT in April 2006

25/9/2006 Dmitri Tsybychev Stony Brook 9 Layer 0 detector The detector consists of: 48 modules mounted on carbon fiber support structure 6  -segments, 8 z-segments Four sensor types provide 98.4% of acceptance Sensors 12 and 7 cm lengths 71 and 81 micron pitch with intermediate strips Signals transferred to readout chips using low mass analog cables

25/9/2006 Dmitri Tsybychev Stony Brook 10

11 Layer 0 Module hybrid analog cable sensor Double-deck analog cable between sensor and hybrid 91  m pitch, shifted by half pitch 17, 24, 32, 34 cm long SVX4 readout chip SVX4 pitch adapter

12 Silicon Readout Data Flow Platform SEQSEQ SEQSEQ SEQSEQ SEQSEQ SEQSEQ SEQSEQ MCH2 3/6/8/9 Chip HDI Sensor 8’ Low Mass Cable ~19’-30’ High Mass Cable (3M/80 conductor) Optical Link 1Gb/s VRBCVRBC VBDVBD VRBVRB Pwr PC SDAQ VME HV / LV 1553 Monitoring 25’ High Mass Cable (3M/50 conductor) CLKs Serial Command Link PDAQ (L3) MCH3 Pwr PC Cathedral Horse Shoe Adapter Card KSU Interface Board SEQ Controller

25/9/2006 Dmitri Tsybychev Stony Brook 13 SMT and Layer 0 Electronics infrastructure DAQ must accommodate both SVX2 and SVX4 Isolated power for SVX4 SVX4 readout chain after IB (new for Layer 0)  digital jumper cable  junction card: impedance matching  twisted pair cable  adapter card SVX4 voltage regulation differential (SVX4)  single ended (existing system) Ground isolation Layer 0 HV Upgraded Sequencer and Sequencer Controller firmware to accommodate coexistence of SVX2 and SVX4

25/9/2006 Dmitri Tsybychev Stony Brook 14 Junction cards Digital Cables LV/HV cables Clocks Twisted pair cables

25/9/2006 Dmitri Tsybychev Stony Brook 15 The Big Challenge – Noise The most difficult challenge (in terms of electronics) for detectors of this type is to reduce noise Analog cable works as a “good” antenna Noise Sources Ground Loops  Continuous carbon fiber structure  Electronics at both ends Power Supplies Noise Other Noise conducted into the detector  Capacitive coupling is very important poorly grounded DØ prototype module total noise diff. noise

25/9/2006 Dmitri Tsybychev Stony Brook 16 Noise elimination – Layer 0 implementation Electronically create an isolated ground on the detector Dedicated adapter card  Use ground isolated power regulators near the detector  All signals sent differentially across the barrier CLC filter before regulators, for SVX4 power Isolated high voltage ground with 10K resistor Isolated ground needs reference to the outside world This is provided by the high voltage ground resistor Mesh spacer to minimize capacitance between analog cables analog cable pitch adapter mesh spacer wrap-around bumpers

17 Other Tricks Carbon fiber cocured with flex circuit with copper trace to achieve better contact Ground pads at backplane of hybrid Wrap-around to connect sensor GND to support (as well as bias voltage to backplane) ground for hybrid wrap-around for ground and bias

25/9/2006 Dmitri Tsybychev Stony Brook 18  pedestal  total noise  10  diff. noise  10 Test stand Without filters With filters Installed in DØ

25/9/2006 Dmitri Tsybychev Stony Brook 19 Noise Performance Outstanding noise performance Typical noise with bias ~1.7 ADC S/N ~ 18 Pedestal peak-to-peak difference 4-5 ADC counts – acceptable Important for online readout occupancy i.e. deadtime. Typical chip threshold 3 *  (~6 counts) above pedestal  pedestal  total noise  10  diff. noise  10

25/9/2006 Dmitri Tsybychev Stony Brook 20 Performance - Charge Distributions More one strip Clusters than MC Better simulation of charge

25/9/2006 Dmitri Tsybychev Stony Brook 21 Hit Finding Efficiency Efficiency somewhat lower in data

25/9/2006 Dmitri Tsybychev Stony Brook 22 CDF Layer-00 (L00) Single sided layer of Silicon Radiation hard 50 micron readout strip pitch Low Mass: 0.6%-1.0% X 0 Mounted directly on Be beam-pipe 6 narrow (r=1.35 cm) and 6 wide (r=1.62 cm) φ segments 12 sensors along z (94 cm) 2.3cm 4.2cm Be Beam-pipe Sensors SVXII Inner bore Cooling channels 300  m installation clearance 72 Ladders / 108 chips

25/9/2006 Dmitri Tsybychev Stony Brook 23 CDF L00 cable1cable2 Signal Cables Narrow Sensors Wide Sensors Hybrids Large coherent noise: Continuous pattern across all strips on a sensor Induced by silicon readout Different event by event Coupling between cables Not usable for trigger

25/9/2006 Dmitri Tsybychev Stony Brook 24 CDF L00 Read all the channels Do pedestal subtraction offline Pedestal fit Event by event fit to find the pedestal distribution Ignoring sharp peaks: real clusters Effectively finds clusters Makes a huge difference in B physics  without L00  with L00

25/9/2006 Dmitri Tsybychev Stony Brook 25 L0 Alignment Pull of the hit residiuals Residual = expected hit position – actual position Default geometry based on the survey data from detector assembly

26 Impact parameter resolution with L0 Impact parameter resolution with Layer 0 30 % improvement  Better for low Pt tracks Magnet off data with cosmic muons

27 Currents Layer 0 currents have been rising slowly since turn-on Initial currents were tiny < 100 nA/detector Expected current rise due to radiation ~1.8  A Jumps between stores in some detectors. These types of detectors are known to be sensitive to surface charge and operation in low humidity. Essentially identical to LHC sensors

25/9/2006 Dmitri Tsybychev Stony Brook 28 SMT Status Enabled ~50 HDI (125 were disabled) Some previous problems reoccur Typical failure modes: No download, chip failures, DVDD trips, no readout, high leakage current Reasons not fully understood Detector is not accessible Part of readout chain in collision hall Connections Cables SVX2 Ageing? Repair work during shutdown 1 Jan, 2006

25/9/2006 Dmitri Tsybychev Stony Brook 29 F-disk Noise “Grassy” noise “Grassy” noise appeared after a several months of operation Only p-side of fraction of the Micron sensor Looks like micro-discharge Charge-up effect observed Micron sensors Eurysis sensors Beam on Beam off

25/9/2006 Dmitri Tsybychev Stony Brook 30 Before Shutdown After Shutdown Comparison

25/9/2006 Dmitri Tsybychev Stony Brook 31 SMT Performance p-side pulse-height (ADC) for a MIP S/N(total) ratio p 9n 6p 6n 3 Heavy flavor tagging Vertex resolution  (cm) 0.01

25/9/2006 Dmitri Tsybychev Stony Brook 32 Summary and Outlook New Layer 0 for DØ silicon detector Installed in April 2006 and fully operational Error free readout Exceptional noise performance Very few bad channels Already see improvement in tracking of charged particles at DØ Pursuing broad physics program