The new ATLAS Track Extrapolation In a case study of a future high - - PowerPoint PPT Presentation

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The new ATLAS Track Extrapolation In a case study of a future high - - PowerPoint PPT Presentation

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The new ATLAS Track Extrapolation In a case study of a future high precision W mass measurement Andreas Salzburger , CERN PH-ATC & University of Innsbruck, Austria Outline Track extrapolation - concept / applications Design of the

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SLIDE 1

The new ATLAS Track Extrapolation

In a case study of a future high precision W mass measurement

Andreas Salzburger, CERN PH-ATC & University of Innsbruck, Austria

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SLIDE 2

Outline

  • Track extrapolation
  • concept / applications
  • Design of the new ATLAS Track extrapolatino engine
  • realization in the new Event Data Model
  • material integration
  • Combined Testbeam 2004
  • first test of new software frame
  • Validation procedure
  • from reconstruction to simulation
  • Prospect of a future W mass measurement
  • scenario for a praxis test

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 3

Track extrapolation: Introduction

The transport of track parameters and their associated covariances is an underlying process of most track fitting algorithms. LHC with its high event rates and track multiplicity requires a very stable and reliable framework for these operations. ATLAS with ist complex geometry (material distribution) and magnetic field needs very precise algorithms to match the requirements of the challenging physics goals.

z x y

p1 a1 a2 p2 a3 p3 B

Global Frame B-Field

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 4

Track extrapolation: Definition and Applications

Can be divided into two basic realms:

  • geometrical transportation of parameters and

covariances

  • update of parameters and covariance matrix

taking multiple Coulomb scattering and energy loss effects into accout

Applicaitons:

  • global and iterative Fitters
  • track – calorimeter matching
  • holes on track search
  • vertex fitter
  • new InDet MC Simulation

Illustration of a typical step in a Kalman filter aplication.

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 5

And this should look like ...

Surfaces TrackParameters TrackParameters

IExtrapolator

ATHENA

ALGTOOL

IPropagator

StraightLinePropagator HelixPropagator RungeKuttaPropagator STEP_Propagator

IPropagator

ATHENA

ALGTOOL

IMaterial Effects Updator

ATHENA

ALGTOOL

INavigator

ATHENA

ALGTOOL

IGeometry Builder

ATHENA

ALGTOOL

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 6

Navigation

The TrackingGeometry enables navigation through the TrackingVolumes which are taken as an interface for material and magnetic field access. If a boundary surface of a TrackingVolume is hit, a simple projection of the momentum vector onto the normal vector of the surface at this point is enough to now the next TrackingVolume, as the BoundarySurface object owns:

TrackingVolume* m_outsideVolume; TrackingVolumeArray* m_outsideVolumeArray; TrackingVolume* m_insideVolume; TrackingVolumeArray* m_insideVolumeArray;

n n p p

PixelBarrel PixelNegEndcap PixelPosEndcap

INavigator

ATHENA

ALGTOOL

  • wns TrackingGeometry,

handles search and navigation

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 7

Material Integration

  • TrackingGeometry provides

mechanism for “Layer based” and “Volume based” material description. Necessarily the TrackingVolume has to be able to hold a Layer or a LayerArray. Material properties should be retrieved from Common Detector Description !! (if possible)

IMaterial Effects Updator

ATHENA

ALGTOOL

STEP_ Propagator

ATHENA

ALGTOOL

Extrapolator

ATHENA

ALGTOOL

steers, decides, configures

Andreas Salzburger – OEPG, Vienna, 27/09/2005

“Volume based” material description (continuous update) “Layer based” material description (point-like update)

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SLIDE 8

Inside SCT Barrel: Magnetic Field map parameterized as a Solenoid

Magnetic Field Access

Andreas Salzburger – OEPG, Vienna, 27/09/2005

Outside SCT Barrel: Realistic Field SCT Barrel Inner Detector

  • The TrackingVolumes have to be

identical or synchronized with MagneticVolumes

  • The CTB 2004 showed: be as flexible

as possible, scaling, shifting, etc. etc.

2nd part: Propagation in realistic field

IMagnetic FieldTool

ATHENA

ALGTOOL

For the moment, TrackingVolumes have a pointer to the MagneticFieldTool which holds synchronized MagneticFieldVolumes.

1st part: Propagation in solenoidal map

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SLIDE 9

Combined Testbeam 2004: A First Testbed

ATLANTIS Event Display 9 GeV, Pions, B=0

Residual gained for ϕ

Full simulation geometry

  • New Extrapolation has been

successfully used in the new Kalman Fitter, the new Gaussian Sum Filter and a new Global Chi2 Fitter. To gain full validation of new software chain, a controlled testbed was needed.

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 10

Suddenly ...

... I remembered vaguely that I‘ve once written a diploma thesis ... ... and I remembered what I didn‘t like so much about the fast simulation ... ATLFAST is in principle not a fast simulation, it is a fast simulation and reconstruction! Which had as a consequence that the fast simulation so far could not be used for any studies that needed hit information, or interaction with the offline reconstruction software.

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 11

Validation testbed: InDetMC_Simulation

  • We need a controlled validation testbed
  • full simulation turned out to be too complex for understanding single underlying processes
  • How to create our ‘perfect’ tracks for validation of the TrkTools

INavigator

ATHENA

ALGTOOL

Navigator of Extrapolation can ‘in principle’ predict the track through the InnerDetector (as connective TrackingGeometry exists).

IExtrapolator

ATHENA

ALGTOOL

IMaterial Effects Updator

ATHENA

ALGTOOL

Special flavour: MC_MaterialEffectsUpdator (enriched with RndGenerator)

InDet::MC_ TrackCreator

ATHENA

ALGTOOL

Trk::Track

trajectory TrackParameters PRD, RIO, TSOS production

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 12

Interaction: InDetMC_Simulation

InDet:: MC_Track Creator

ATHENA

ALGTOOL

  • Allows interaction:
  • resolution of detectors
  • efficiency (holes on track creation)
  • misalignment etc.
  • clustering, RIO_OnTrackCreation

IGeometry Builder

ATHENA

ALGTOOL

  • Allows interaction:
  • detector setup
  • material distribution

IMaterial Effects Updator

ATHENA

ALGTOOL

  • Allows interaction:
  • particle type
  • different models for E-Loss/MS

IFitter

ATHENA

ALGTOOL

  • Allows:
  • simple switch between used fitting

technique,

  • cross checks, etc.

Cake - Prolonging the Magic – “You turn the screws”

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 13

Application: W mass

The W mass in the Standard model:

) 1 ( sin 1 2

2 2

r G m

W F W

∆ − = θ πα

measured precicely at LEP (0.004 %) known to 0.0009 % from muon lifetime measured to 0.014% at the Z pole radiative corrections, dominated by

mt, mH W mass is sensitive for Higgs mass, but also for new physics such as SUSY particles due to loop corrections.

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 14

Application: W mass measurement in ATLAS

ν l W →

In p-p collisions, the W mass can be obtained from the leptonic decay channels: Longitudinal momentum of neutrino can not be measured, measurement is done by an extraction from the transverse mass distribution where l = e, µ

) cos 1 ( 2 φ

ν

∆ − =

T T T

p p m

l

pT

e

pT

W

ET ET

Neutrino

H a d r

  • n

i c r e c

  • i

l

The transverse neutrino momentum is reconstructed using teh transverse momenta of the lepton and the hadronic recoil of the underlying event. Due to high event rate, the measurement error will be completely determined by systematical error.

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 15

Systematic Errors: W mass measurement in ATLAS

Thanks to Esben Klinkby et al.

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 16

The analysis: W mass measurement in ATLAS

The kinematic boundary is smeared by the detector response, this smearing has to be perfectly understood (maerial distribution, magnetic field properties) to guarantee the fit. Generating large event numbers with full simulation and different input W mass values and fit the edge in comparison to taken data would be a strategy, but this is almost inpossible due to the time- consuming Geant4 simulation. The idea is to retry that with the new InDetMC_Simulation, that is up to two to three magnitudes faster. + full control of the sim/reco material + full control of the sim/reco magnetic field

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 17

Current Status: Simulation and refitting of single tracks

InDetTrackingGeometry + Navigation validation finished Material distribution + calibration framework established Proof of principle with InDetMC_Simulation and new Kalman Fitter

Todos: • redo with adapted material to different ATLAS layouts

  • interface InDetMC_Simulation with generator output
  • feed fast simulated and reconstructed files into existing W mass measurement

framework

  • chagne sim/reco material and deduce the systematics

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 18

Conclusion: so far

  • New Track extrapolation scheme has been established
  • used in CTB 2004 reconstruction
  • base of many new fitters and filters in the ATLAS offline software
  • also used in physics analysis applications already
  • Two basic novelties
  • STEP propagator (continous material effect update)
  • Full connective TrackingGeometry (Navigation)
  • Navigation enables new fast MC Simulation for ATLAS
  • more than smearing can be done
  • used for various validation studies already, but need improvement
  • Prospect of a future W mass measurement
  • can we answer the questions of lepton energy scale ?

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 19

Backup slides …

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 20

Material comparison Geant4 / InDetTrackingGeometry – Atlas release 10.2.0

Andreas Salzburger – OEPG, Vienna, 27/09/2005

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SLIDE 21

Andreas Salzburger - Ibk, 02/08/2005

THE EDM AFFAIR

working title: „THE RTF REPORT“

The ATLAS offline software has been for a long time characterized by (mainly two) black-box like reconstruction programs with no interaction no possbility to compare internal algorithms and assumptions. Severall attempts to create a common ATLAS Event Data Model to guarantee interchangeability between programs from different authors failed in the past (RD Event), etc. Despite the fact that no-one ever came back who tried to do this task, a young group of Fellows and PhD students, inpired by the guideline of the „Final Report of the Reconstruction Task Force (RTF)“, tried to do the undoable and ... ... after a long walk, after barriers and fallbacks ...

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SLIDE 22

Andreas Salzburger - Ibk, 02/08/2005

THE EDM AFFAIR The new Track class was born, a subdetector-indpendent container for what should be known as a track. By January this year, with the introduction of the last converter of a major reconstruction program to the new track class, the battle was won (so they say). Today, this gives me the small ‚overhead‘ of being in charge of following EDM/Geometry/MagneticField packages: TrkEventUtils TrkEvent TrkEventPrimitives TrkMeasurementBase TrkSegment TrkParameters TrkDetDescrUtils TrkDetDescr TrkSurfaces TrkVolumes TrkGeometry TrkDetElementBase TrkMagFieldUtils TrkMagneticField

Then ... I just had a little extrapolation package left ...