SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt1 SVT The CDF Silicon Vertex Trigger Vertex 2002 Luciano Ristori Istituto Nazionale di Fisica Nucleare Pisa – Italy

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt2 SVT The Silicon Vertex Trigger was designed and built for the CDF collaboration by people from the following institutions: INFN – Pisa INFN – Trieste University of Chicago Université de Genève

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt3 CDF DETECTOR

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt4 CDF r-z view

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt5 SVX II 2.5 cm 10.6 cm 90 cm

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt6 Why and how? Trigger on B hadronic decays –B physics studies, eg. CP violation in B decays, Bs mixing –new particle searches, eg. Higgs, Supersymmetry A b-trigger is particularly important at hadron colliders –large B production cross section for B physics –high energy available to produce new particles decaying to b quarks –overwhelming QCD background need to improve S/B at trigger level Detect large impact parameter tracks from B decays using the fact that  (B)  1.5 ps secondary vertex primary vertex Technical challenge!

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt7 SVT: Silicon Vertex Trigger Inputs: – L1 tracks from XFT ( , p T ) – digitized pulse heights from SVX II Functionalities: – hit cluster finding – pattern recognition – track fitting Outputs: – reconstructed tracks (d, , p T )

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt8 60 Hz ~20MB/s 300Hz 45 kHz Central Tracker (Pt,  ) EM + HAD/EM + Track EM+HAD (Jet) Muon + Track Missing E T,  E T Si Secondary vertex EM shower max, ISO Jet Clustering Multi object triggers Farm of ~200 PC’s running fast versions of Offline Code  more sophisticated selections Triggering in Run 2

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt9 CDF Run II trigger architecture  DØ results Tracking system –central outer tracking (COT) –silicon tracking (SVX II & ISL) three-level trigger –L1: 5.5  s pipeline XFT: L1 2D COT track –L2:  20  s processing time two stages of 10  s SVT at stage 1 of L2 –SVX II readout –hit cluster finding –pattern recognition –track fitting CAL COT MUON SVXCES XFT XCES MUON PRIM. XTRP SVT L2 CAL L1 CAL GLOBAL L1 MUON L1 TRACK GLOBAL LEVEL 2 TSI/CLK detector elements

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt10 Finding tracks in the silicon

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt In this example: Straight lines, 5 layers, 12 bins/layer Total number of patterns ~ (12) 2 *(5-1) = 576 Instead of looking for hit combinations such that f(x1,x2,x3,…) = 0 1.Build a database with all patterns corresponding to “good” tracks 2.Compare hits in each event with all patterns to find track candidates Building the “Pattern Bank”

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt12 AM chip internal structure

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt13 AMchip

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt14 Amplug: mezzanine board

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt15 AM Board VME AMbus x Amchips x 128 patterns each = 16K pattern board

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt16 SVT basic architecture Pattern recognition and track fitting done separately and pipelined Hits Hit Buffer Roads Roads + hits Track Fitter Associative Memory Tracks (d, p T,  ) Pattern recognition with Associative Memory (AM) highly parallel algorithm using coarser resolution to reduce memory size Fast track fitting with linear approximation using full resolution of the silicon vertex detector Hits

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt17  x i Non-linear geometrical constraint for a circle: F(x 1, x 2, x 3, …) = 0 But for sufficiently small displacements: F(x 1, x 2, x 3, …) ~ a 0 + a 1  x 1 + a 2  x 2 + a 3  x 3 + … = 0 with constant a i (first order expansion of F) From non-linear to linear constraints

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt18 Constraint surface

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt19 SVT Wedges

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt20 SVT system architecture Hit Finders Merger Associative Memory Hit Buffer Track Fitter to Level 2 COT tracks fromXTRP 12 fibers hits roads hits x 12 phi sectors Sequencer raw data from SVX front end

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt21 SVT: board count Hit Finders42 Mergers16 Sequencers12 AMboards24 Hit Buffers12 Track Fitters12 Spy Controls 8 XTFA 1 XTFB 2 XTFC 6 Ghostbuster 1 + spares INFN INFN & Geneva University of Chicago TOTAL 136

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt22 CPU Tracer Spy ControlAssociative Memory Hit Finder Sequencer Merger Hit Buffer Track Fitter XTFA XTFB XTFC SVT: board and crate layout

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt23 Hit Buffer board

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt24 Hit Finder board

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt25 Merger board

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt26 SVT crates in CDF counting room

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt27 Impact parameter vs. phi Subtracted x y phi d d = y cos(phi) – x sin(phi) d phi d Raw

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt28 SVT: beam profile sigma ~ 50 um ~ 43 um + 25 um SVT resolutionbeam spot size This distribution is interpreted as the convolution of the actual transverse size of the beam spot with the impact parameter resolution of the SVT Impact parameter distribution

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt29 Tevatron Beam Moves! Beam center at beginning of store normally stable within 20 microns. Drift during the duration of a store of 20 to 30 microns in x,y (often correlated) Beam slope more stable (variation <20 microradians) TeV store ~12 hours 25 microns x position (  m) y position (  m) x slope (  rad) y slope (  rad)

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt30 Hadronic B decays with SVT L1: Two XFT tracks P t > 2.5 GeV; P t1 + P t2 > 6.5 GeV  < 135° L2: d 0 >100  m for both tracks Validation of L1 cuts with  >20° Lxy > 200  m d 0 (B)<140  m Two body decays L1: Two XFT tracks P t > 2.5 GeV; P t1 + P t2 > 6.5 GeV  < 135° L2: d 0 >120  m for both tracks Validation of L1 cuts with  >2° Lxy > 200  m d 0 (B)<140  m Many body decays Two 3 x cm -2 s -1 ~ 3 KHz ~ 5 Hz

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt31 CDF as a Charm factory?

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt32 Fully Hadronic B decays

SVT Nov 7, 2002Luciano Ristori - Vertex2002_7Nov02.ppt33 SUMMARY The design and construction of SVT was a significant step forward in the technology of fast track finding We use a massively parallel/pipelined architecture combined with some innovative techniques such as the associative memory and linearized track fitting SVT is now fully commissioned and we have shown we can handle all the technical challenges related to detector and beam alignment in real time Performance of SVT is as expected CDF is triggering on impact parameter and collecting data we hope will soon lead to significant physics results