May 14, 2001C.Rott1 The CMS Forward Pixel Detector Carsten Rott Purdue University May 14, 2001

May 14, 2001C.Rott2 The LHC Technically extremely challenging Luminosity Center of mass energy pp collider 26.67km circumference Accelerator Detector Radiation damage High occupancy Interaction rate 25ns

May 14, 2001C.Rott3 Physics at the LHC Higgs search LEP II exclusion limit m H <113.5GeV LHC will cover expected Higgs mass range completely Bottom physics Top physics Extension of standard model will allow us to explore physics at the TeV scale

May 14, 2001C.Rott4 Pixels/blade 24 Blades/disk The CMS Detector Barrel + Forward Pixel Disks FPIX-Disk

May 14, 2001C.Rott5 The Blade The HDI connects the Plaquettes to the outside world Plaquette Sensor ROC VHDI Kapton, HDI Be Panels PSS

May 14, 2001C.Rott6 The Plaquette Sensors ROC Pump Bonded to Plaquette VHDI 2 metal layers flex on 300  m Si

May 14, 2001C.Rott7 How does a Pixel Detector work? NN+N+ P+P H.V. Semiconductor detectors are “diodes” By applying a reverse bias voltage to it the depletion zone can be enlarge until it the sensor is fully depleted If an ionizing particle passes through the bulk it creates electron-hole pairs Charge carriers move in the E-field and are collected to give the signal Pixels Pixels with indium bumps

May 14, 2001C.Rott8 FPIX Beam Test at CERN DAQ 3T magnet Si-strips Repeater card Fibers Scintillator The telescope

May 14, 2001C.Rott9 Repeater Card with Pixel Sensor Pixel Data 150  m x  m pixel thickness 270  m 22x30 pixel array unirradiated sensor rad. hard DMILL ROC

May 14, 2001C.Rott10 250GeV/c pion beam Repeater card can be rotated Can trigger on region as. small as 1mm 2 The Telescope   Beam Si-Strips vertical Si-Strips horizontal Scint. Counters   X/Y-Fibers 1mm Dia. few mm 2 Extrapolated track  x = 2.0  m  y = 3.6  m  Pixel Detector and Repeater Card

May 14, 2001C.Rott11 Correlations Pixel hits in coincidence with the telescope trigger A clear correlation can be seen

May 14, 2001C.Rott12 Pedestal System shows correlated noise Adjacent pixelNon-adjacent pixel

May 14, 2001C.Rott13 Signal height: Noise: Signal to noise ratio of 60 S/N and Efficiency An absolute efficiency could not be measured because of a time stamp problem. A strong correlation between tracked position and pixel hit position, suggests high efficiency.

May 14, 2001C.Rott14 Charge sharing between rows (rotated by 20 o ) Charge sharing between rows (not rotated) 150  m PH is 12bit ADC value Charge sharing is increased by rotating the sensor Charge sharing can be used to improve the resolution Charge Sharing Comparison

May 14, 2001C.Rott15  Distribution Position correction curve  is the difference of the fraction of charge deposited in the neighboring pixel A is a normalization factor  vs position ( 20 o rotation angle)

May 14, 2001C.Rott16 Resolution in micron between rows (rotated by 20 o ) Resolution in micron between rows (not rotated) Resolution

May 14, 2001C.Rott17 Resolution 0 0 rotation 20 0 rotation Highest resolution for large charge sharing and hits in between pixel

May 14, 2001C.Rott18 Magnetic Field Sensors at 20 o with beam B=3T parallel to beam No asymmetry can be seen The Lorentz angle  is defined as the angle between the drift direction and the electric field Lorentz angle could not be measured experimentally

May 14, 2001C.Rott19 Results from the Beam Test No surprises Charge sharing can improve the resolution Resolution at 20 0 rotation  m Resolution at 0 0 rotation  m Resolution is position dependent S/N = 60 High efficiency

May 14, 2001C.Rott20 Importance of Pixel System Crucial role for success of the experiment High resolution Separation of particle tracks Fast signal Able to deal with a high occupancy Flavor tagging Close to primary vertex

May 14, 2001C.Rott21 The Future of New Physics Max. integrated Luminosity Interaction Energy First collisions2006 LHC starts now Tevatron Integrated Luminosity Interaction Energy Data taking CDF RUN II is a great opportunity to do new physics

May 14, 2001C.Rott22 New Physics at the Tevatron Important for new physics Produce it Find it Identification of objects that make up the signature Understanding of the calibration and resolution of the detector Understanding background With a center of mass energy of 2TeV and an integrated luminosity of in RunII D0 and CDF will be able to extend searches to new parameter space

May 14, 2001C.Rott23 Example:”Light Stop search” R-Parity: Quantum number R P SUSY

May 14, 2001C.Rott24 New Physics involving Heavy Flavor Jets Susy Heavy Gauge Bosons Technicolor Higgs 4. Gen quarks

May 14, 2001C.Rott25 How do we look for it ? Is there more ? Signature based searches SLEUTH Typically: Chose model, signature Backgrounds, model efficiency Optimize cuts Data, limit  xBR Limit model param. Model based search Problem: the number of competing candidate theories is large !

May 14, 2001C.Rott26 How do we look for it ? Typically: Chose model, signature Backgrounds, model efficiency Optimize cuts Data, limit  xBR Limit model param. Model based search A different way: Chose signature Study backgrounds Chose cuts, vary cuts Efficiencies Limit  xBR Signature based search

May 14, 2001C.Rott27 Signature Based Searches Understanding data rather than what the data has to say about one specific model Objects of interest Some of the objects can be treated in parallel

May 14, 2001C.Rott28 Tracks in a jet fall into 3 categories decay tracks from heavy hadron fragmentation tracks tracks coming from other interactions in the event Flavor Tagging CDF has many different specialist algorithms depending on the physics you want to do To find a jet use information from the tracker and calorimeter Goal: want to identify the particle that created the jet Understand the jet and identify parameters that can be used to distinguish between them

May 14, 2001C.Rott29 Status (Understand Jets) My Event Viewer Generator (Pythia, Isajet) Production Simulation Analysis Program (modified Secvtx) Questions Performance of current jet tagging algorithms How does a jet look like What information can be used to distinguish jets   (Monte Carlo sample )

May 14, 2001C.Rott30 Conclusions The work on the CMS Forward Pixel system was a great experience and will be an enormous help for my future work with vertex detectors Beam test at CERN was challenging and great learning experience CDF has the potential to discover new physics Signature based searches have greater chance of identifying an anomaly in the data Lots of new physics is expected to produce jets Flavor-tagging is crucial to distinguish signatures Looking forward for the first data from CDF