First physics results with the Silicon Vertex Trigger at CDFII

1
First physics results with the Silicon Vertex
Trigger at CDF-II

• 2nd Workshop on the CKM Unitarity triangle.
• April 5th-9th
• IPPP Durham, England, UK
• Ivan Vila
• Instituto de Fisica
• de Cantabria

2
Outline

• SVT motivation and overview.
• SVT performance.
• Charm and B physics with the SVT
• Hadronic triggers
• Semileptonic triggers
• Summary

Related CDF talks Review on B lifetimes and
lifetime differences J. Rademacker Bs mixing
results and prospects at CDF/D0 D.
Lucchesi Performance of CDF for B Physics
R. Oldeman
3
B physics at Tevatron

• Large b production cross-section
• s(bb) 100mb (10kHz _at_ E32)
• s(B, ylt1, PTgt6) 3mb (300Hz _at_ E32)
• compare s(bb) 1nb at U(4S) (5Hz _at_ 5E33)
• Many B hadrons states produced
• B0, B, Bs, Lb, Bc, ?b
• But HUGE inelastic cross section 100mb
• A dedicated trigger needed

4
A new tool for selecting Bs

• CDF has three dedicated triggers for B/Charm
  physics
• Dimuon
• J/ygmm
• Lepton track
• Semileptonic decays
• Two track
• Hadronic decays

Only available for Run I
Implemented by the Silicon Vertex Trigger
1 mm
b, c decays
primary vertex
Silicon microstrip detector included in trigger !
secondary vertex
impact parameter
5
Trigger Overview

• Bunch crossing 396 ns 2.5 MHz
• Level 1 fast programmable logic
• Synchronous 5.5 ms latency
• Calorimeter, Muon, Tracks
• Accept rate 15kHz (reduc. x200)
• SVT trigger paths 40 bandwidth
• Level 2 programmable logic CPU
• Asynchronous 20 ms latency
• Cal cluster, Silicon track
• Accept 300 Hz (reduction x50)
• SVT trigger paths 17 bandwidth
• Level 3 Linux PC farm
• Offline quantities
• 50 Hz (reduction x6)
• SVT trigger paths 25 bandwidth

6
SVT key techniques

• How do we do silicon track reconstruction in
  about 15 microseconds?
• (1) Do everything you can in parallel and in a
  pipeline.
• (2) Pattern recognition
• Database with all patterns corresponding to good
  tracks
• Compare in parallel hits in each event with
  previous patterns to find track candidates
• Bin coordinate information coarsely into roads.
• This is done in a custom VLSI chip (Associative
  Memory).
• (3) Linearize the fitting problem.
• i.e. solvable with matrix arithmetic

7
SVTPattern Recognition
The AM chip is the physical realization of the
template matching pattern recognition algorithm
each AM Chip can compare each hit with all the
patterns in memory in parallel, providing the
high speed necessary for trigger
applications. With the AM, pattern recognition is
complete as soon as the last hit of an event is
read! Like in a bingo game.

• Coarser resolution
• 250 ?m superstrips
• 95 coverage
• each 30o slice
• 2AM boardx128chipsx128roads32.000 roads

8
SVT Performance precise and fast
24 ms Level 1 accept to SVT done 9 ms before the
first hit is received 15 ms processing time

• IP resolution 50 mm
• Includes 33 mm beam spot
• Beam position is computed at real time and
  subtracted online

9
SVT PerformanceEfficiency

• Efficiency evaluated on a sample of J/? ? ??

Efficiency can still be improved by requiring 4
hits out of the five SVX layers, so far 4 out of 4
10
SVT PerformanceOnline monitor.
Using tracks found at L3 calculate K? invariant
mass Excellent online trigger Monitor The
number of D0 per luminosity unit has to remain
constant if detector and trigger are performing
well.
11
The Two Track Trigger

• 2Tracks with PTgt2. GeV, SVT 1 mm gt IP gt120mm
  PT1PT2 gt5.5 GeV
• Collect 70 pb-1 of Data 0.5M D0gKp signal
• Will have O( 107 ) fully reconstructed decays in
  2 fb-1 data set !!
• Competive, compare FOCUS todays standard for
  huge
• 139K D0?K-p, 110K D?K-pp
• Charm production cross section measured and
  compatible SM

12
The Two Track Trigger (2)

• Very high purity D0 signal using D tag
  technique
• DgD0p
• M(D)M(D0)
• s(MD) 10 MeV
• s(DM) 0.6 MeV
• 20 of the D0 D tagged

• Eliminate the reflection background (D0gKp and
  pK)
• Initial flavor of D0 is known
• D g D0 p / D- g D0 p-
• The best place to study D0 mixing and CP
  violation

13
The Two Track Trigger (and 3)

• Ds, D g fp f gKK
• 10 pb-1 of two track trigger
• Measure mass difference
• 99 0.38 0.21 MeV/c2
• PDG 99.20.5 MeV (CLEO2, E691)

• Momentum scale of the tracking detector is
  calibrated using the J/ygmm
• Then extensively tested using Ksgpp, D0gKp, Ugmm,
  

First Run II paper !
DM
14
Lepton Track Trigger

• Lepton Track 1 m/e pTgt 4 GeV 1 other track
  with pT gt 2 GeV, SVT 1mm gtIP gt 120 mm and
  M(l-Track) lt 5 GeV
• Collect 60 pb-1 of data 0.5M B g lX signal

• Lepton Track dataset (60 pb-1)
• BglD0X (D0gKp) 10K
• BglDX (DgD0p) 1.5K
• BglDX (DgKpp) 5K
• Good signals for calibration
• Measure B and B0 lifetime
• Study B0-B0 mixing

15
Lepton Track Trigger (2)

• Bs g ln DsX (Dsgfp)

• Lb g lnLcX (LcgpKp)

Lifetime studies 0.12 ps
(PDG0.08 ps) Future semileptonic form factor
Lifetime studies 0.07 ps
(PDG0.057 ps) Future Bs mixing (low Dms case)
16
Summary

• The Silicon Vertex Trigged significant step
  forward in the quality of fast track finding in
  hadron collider physics.
• A massively parallel/pipelined architecture was
  used combined with innovative techniques the
  associative memory and linearized track fitting
• A world plenty of Charm
• Used as benchmark for B two body charmless
  decays.
• The large statistics CDF as world class charm
  factory.
• B fully hadronic and semileptonic decays are
  under reconstruction
• First physics measurements using SVT based
  samples.
• Getting ready for the large luminosity Bs
  mixing, Lb and Bs lifetimes, sin 2b

17
Back up slices

• JUST IN CASE

18
CDF II
19
Tevatron
D0
CDF
Tevatron
Lpeak 1x1032s-1cm-2 Bunch spacing 396 ns
p source
Main Injector Recycler
20
Integrated Luminosity
Jan 03
Data used for Todays results Mar 02 Jan 03
130 pb-1 (delivered) 100 pb-1 (to tape) Jet
physics 85 pb-1 B/Charm 70 pb-1
commissioning
21
SVTTrack Fitting
22
SVT for B0 ? ????
1 MHz
SVT
1 kHz
20 Hz
1 Hz
picobarns

• SVT reduces the background rate by a factor of
  1000
• data recording possible by DAQ

23
Fake rate
24
Charm Xsec