# Presentation: 497477

## 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

**Notes:**
The title of this talk is .... And next slide

## 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

- I. Vila  2nd CKM Workshop  Durham

- April '03

**Notes:**
...and this is the outline. I will start explaining why do we want 

## B physics at Tevatron

- Large b production cross-section
- (bb) ~ 100b (10kHz @ E32)
- (B+, |y|<1, PT>6) ~ 3b (300Hz @ E32)
- compare: (bb) ~ 1nb at (4S) (5Hz @ 5E33)
- Many  B hadrons states produced:
-  B0, B+, Bs, b, Bc, b
- But... HUGE inelastic cross section ~ 100mb
- A dedicated trigger needed

- I. Vila  2nd CKM Workshop  Durham

- April '03

**Notes:**
Why do we want to do B physics in a hadron collider as the Tevatron?
We can do great even comparing ourselves with a B factory.
Deticated trigger to suppress the background without killing the signal.

## A new tool for selecting B’s

- CDF has three dedicated  triggers for B/Charm physics
- Dimuon
- J/
- Lepton +   track
- Semileptonic decays
- Two track
- Hadronic decays

- Only available for Run I

- Implemented by the
- Silicon Vertex Trigger

- primary vertex

- secondary vertex

- impact parameter

- ~ 1 mm

- Silicon microstrip detector
- included in trigger !

- b, c decays

- I. Vila  2nd CKM Workshop  Durham

- April '03

**Notes:**
How are we selecting heavy flavors in CDF? 

What are the practical implications of the trigger ? 

Sensitivity enhancement selecting displaced tracks from b hadron decays. 
We can select event leptons with lower momentum (during run I 6-8 GeV)
Hadronic decays accessible improvement of Lorentz boost factor
which better measurement of the proper time of particles which will increase our
Sensibility to disentangle the fast Bs oscillations

The basic idea is to cut on the non zero impact parameter of the particles coming from
The decay of b and charm hadrons decay, supressing the not displaced background track
From the background. 

THIS IS THE FIRST TIME  THE SILICON MICROSTRIP VERTEX DETECTOR
 IS INCLUDE IN THE TRIGGER SISTEM OF A HADRON COLLIDER.

## Bunch crossing: 396 ns: 2.5 MHz

Level 1: fast programmable logic
Synchronous 5.5 s latency
Calorimeter, Muon, Tracks
Accept rate 15kHz (reduc. ~x200)
SVT trigger paths ~ 40% bandwidth

Level 2: programmable logic + CPU
Asynchronous ~ 20 s 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

- Level 1: fast programmable logic
- Synchronous 5.5 ****s latency
- Calorimeter, Muon, Tracks
- Accept rate 15kHz (reduc. ~x200)
- SVT trigger paths ~ 40% bandwidth
- Level 2: programmable logic + CPU
- Asynchronous ~ 20 ****s 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

- Trigger Overview

- I. Vila  2nd CKM Workshop  Durham

- April '03

**Notes:**
How the svt fits in the trigger system ?

CDF trigger system is a pipelined si almost a
dead-time-less trigger system 
 Event selection is done in three steps. 
This are the current trigger figures.

Phi0 and Pt are improved also... 

## 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

- I. Vila  2nd CKM Workshop  Durham

- April '03

## SVT:Pattern 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 boardx128chipsx128roads~32.000 roads

- I. Vila  2nd CKM Workshop  Durham

- April '03

## SVT Performance: precise and fast

- IP resolution ~ 50 m
- Includes 33 m beam spot
- Beam position is computed at real time and subtracted online

- 24 s Level 1 accept to SVT done
- 9 s before the first hit is received + ~ 15 s processing time

- I. Vila  2nd CKM Workshop  Durham

- April '03

## SVT Performance:Efficiency

- 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

- I. Vila  2nd CKM Workshop  Durham

- April '03

## SVT Performance:Online 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.

- I. Vila  2nd CKM Workshop  Durham

- April '03

## The Two Track Trigger

- 2Tracks with: PT>2. GeV, SVT 1 mm > IP >120m &   PT1+PT2 >5.5 GeV
- Collect ~70 pb-1 of Data ~ 0.5M D0K signal
- Will have O( 10**7 **) fully reconstructed decays in 2 fb-1 data set !!
- Competive, compare  FOCUS  today’s standard for huge:
- 139K D0K-p+, 110K D+K-p+p+
- Charm production cross section measured and  compatible SM

- I. Vila  2nd CKM Workshop  Durham

- April '03

## The Two Track Trigger (2)

- Very high purity D0 signal using “D* tag” technique
- D*+D0
- M(D*)–M(D0):
-  (MD)  ~ 10 MeV
-  (M) ~  0.6 MeV
-  20% of the D0 : D*+  tagged

- Eliminate the “reflection” background (D0K and K)
- Initial flavor of D0 is known
-  D*+  D0 + +  / D*-  D0 + -
-  The best place to study D0 mixing and CP violation

- I. Vila  2nd CKM Workshop  Durham

- April '03

**Notes:**
An even cleaner sample

## The Two Track Trigger (and 3)

- Ds, D+   ;  KK
- 10 pb-1 of two track trigger
- Measure mass difference
-  99 ± 0.38 ± 0.21 MeV/c2
- PDG: 99.2±0.5 MeV (CLEO2, E691)

- Momentum scale of the tracking detector is calibrated using the J/
- Then extensively tested using Ks, D0K, , ...

- M

***First Run II paper !***

- I. Vila  2nd CKM Workshop  Durham

- April '03

## Lepton + Track Trigger

- Lepton + Track : 1 /e  pT> 4 GeV +1 other track with pT > 2 GeV, SVT 1mm >IP > 120 mm and M(l-Track) < 5 GeV
- Collect ~60 pb-1 of data ~ 0.5M B g lX signal

- Lepton + Track dataset (60 pb-1)
-  BlD0X (D0K) : ~ 10K
-  BlD*+X (D*D0): ~ 1.5K
-  BlD+X (D+K): ~ 5K
- Good signals for calibration
-  Measure B+ and B0 lifetime
-  Study B0-B0 mixing

- I. Vila  2nd CKM Workshop  Durham

- April '03

## Lepton + Track Trigger (2)

- Lifetime studies ~ 0.07 ps
-               (PDG:0.057 ps)
- Future: Bs mixing (low ms case)

- Lifetime studies ~ 0.12 ps
-                 (PDG:0.08 ps)
- Future: semileptonic form factor

- Bs  l DsX (Ds)

-  b  lcX (cpK)

- I. Vila  2nd CKM Workshop  Durham

- April '03

## 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, b and Bs lifetimes, sin 2b...

- I. Vila  2nd CKM Workshop  Durham

- April '03

## Back up slices

- JUST IN CASE...

- I. Vila  2nd CKM Workshop  Durham

- April '03

## CDF II

- I. Vila  2nd CKM Workshop  Durham

- April '03

## Tevatron

- D0

- CDF

- Main Injector & Recycler

- p source

- Lpeak:
- ~1x1032s-1cm-2
- Bunch spacing:
- 396 ns

- I. Vila  2nd CKM Workshop  Durham

- April '03

## Integrated Luminosity

**Data used for Today’s results **
**Mar 02 – Jan 03**
**  ****130 pb****-1**** (delivered)**
**  ****100 pb****-1**** (to tape) **
**   ****Jet physics: ~ 85 pb****-1**
**   ****B/Charm:      ~ 70 pb****-1**

- Jan 03

- commissioning

- I. Vila  2nd CKM Workshop  Durham

- April '03

## SVT:Track Fitting

- I. Vila  2nd CKM Workshop  Durham

- April '03

## SVT for B0   

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

- SVT

**1 MHz**

**20 Hz**

**1 Hz**

**1 kHz**

- picobarns

- I. Vila  2nd CKM Workshop  Durham

- April '03

## Fake rate

- I. Vila  2nd CKM Workshop  Durham

- April '03

## Charm Xsec

- I. Vila  2nd CKM Workshop  Durham

- April '03