CHEP06, Mumbai-India, Feb 2006V. Daniel Elvira 1 The CMS Simulation Validation Suite V. Daniel...

CHEP06, Mumbai-India, Feb 2006 V. Daniel Elvira 1

The CMS Simulation Validation Suite

V. Daniel Elvira (Fermilab)

for the CMS Collaboration


Simulation Software in CMS

Detector Simulation

Generation Digitization

Pool HepMC data file

Pool SimHit data file

Pool Digi data file

Reconstruction

Generation – MC truth information from particle gun or physics generator about vertices and particles. Stored in HepMC format.

Detector Simulation – Hit objects with timing, position, energy loss information. Based on the Geant4 tool kit.

Digitization – Constructs Digi objects which include realistic modeling of electronic signal.

Reconstruction – Physics Objects: vertices, photons, e, , jets,……


Physics Software Validation

Elements to validate:

• Geometry description & magnetic field map• Physics of EM and Had showers in Geant4 - hits• Digitization Model - digis• Reconstruction Algorithms – physics objects

For absolute validation: Use visualization tools, TB experiments, reference plots

The Simulation Validation Suite (SVS) validates in an automated way each new release of the CMS simulation software, comparing values of quantities related to geometry, field, hits with reference values from a previously (absolutely) validated version.

Expansion to “Physics Software Validation Suite” including digis, reco ……in progress


CMS Detector Systems

22 m long & 15 m in diameter

Solenoid Magnet: 4 Tesla Field

Electromagnetic Calorimeter (Ecal)

Hadronic Calorimeter (Hcal)

Silicon Tracker

Muon System

More than 1 Million Geometrical volumes

SVS modular structure follows the detector sub-systems


SVS: General Description

SVS software sub-systems(dedicated simulation packages)

Pre-generated samples: single particles, pp physics

(Pool files, ROOT browsable, HepMC format)

OVAL: testing tool created by CMS to detect changes in software behavior.Used as the SVS integration tool. It executes scripts and shell commands to control the suite execution and perform comparison tests.

SimG4TrackerValidationSimG4EcalValidationSimG4HcalValidationSimG4MuonValidationSimG4GeomValidationSimG4FieldValidationSimG4GlobalValidation

Validation branch(Pool files, ROOT browsable)

On the fly analysis: basic G4 objects processed into information to construct validation quantities.

OVAL

Configuration file: commands, tolerance values


SVS: General Description (II)

ROOT Analysis Macros

• Construct Validation Quantities• Create/fill histograms• Read reference files• Perform Validation Tests: or Kolmogorov-Smirnov

Validation branch (Pool files, ROOT browsable)

One or more tests per sub-detector: low/high level quantities, different sub-detector components.

Reference Histograms from previous version(ROOT file)

List of differences for quantities not passing the tests (ASCII files)

OVAL

Configuration file: commands, tolerance values

Results are reviewed by system experts: approve & release, or investigate problems

(LCG PI Statistics Testing toolkit, or ROOT)


Tracker Validation Tracking system:

Silicon Strip Tracker - Tracker Inner Barrel (TIB), Tracker Outer Barrel (TOB), Tracker Inner Disks (TID) and Tracker End Cap (TEC) Pixel Detector - Pixel Barrel and Pixel End Cap.

Validation Quantities:Energy depositionDistribution of track entry and exit pointsNumber of hitsTime of flight,……, etc

Sample: Single muons, electrons or pions with pT =15 GeV in 12 bins of in the range -3<<3 (1,500 events)

Reference Distribution

Current Distribution

Identical Distributions


Ecal Validation

Electromagnetic Calorimeters: Ecal Barrel – Ecal Endcap (crystals) Preshower (Si/lead)

• vs hit occupancy in crystals• E1, E2x2, E3x3, E4x4, E5x5 depositions• E1/E4, E4/E9, …, E9/E25 ratios• Percent of E in Barrel, Endcap, Preshower• Longitudinal shower development

Low Level Test: Single 30 GeV photons (2,000 events)

• E25 resolution vs the incident energy• Longitudinal shower development vs energy• Coefficient of Lead absorption vs incident energy (preshower)

High Level Test: Single 10GeV, 20GeV, 30GeV, 40GeV, 50GeV (2,000 events)


Ecal Validation (II)


Hcal Validation Hadronic Calorimeters: Hcal Barrel – Hcal Endcap (copper/scint.) Hcal Forward (steel/quartz fibers)

• E depositions in each HB layer• Time dist. of Hit energy in 7x7 tower matrix• Number of hits in Ecal and Hcal• Energy in 1x1, 3x3, 5x5 tower matrices

Single 50 GeV pions (1,000 events)

Layer 0

Time distributionin 7x7 tower matrix

• Total energy in Hcal• Total energy in long fibers (HF)• Total energy in short fibers (HF)• …………


Muon Validation Muon System: Drift Tubes (DT) in central region. Cathode Strip Chambers (CSC) in forward region. Resistive Plate Chambers (RPC) in both for trigger. Single 100 GeV muons (1,000 events)

E lost by in full CMS detector For 100 GeV <E>~8 GeV

For each muon:

• Energy lost• Deviation in position• Deviation in angle (deg)• Number of tracking steps

For each type of muon process (ionization, bremsstrahlung, e+e− production, muon nuclear interaction, decay and capture):

• Energy of secondary particles• Angle of secondary track with respect to primary muon track


Geometry ValidationComputes the number of volumes and materials and the total number of radiation lengths through the CMS detector.

Sample

• The geometry summary: number of different materials, number logical volumes, physical volumes.• The number of radiation lengths after traversing the full detector.

Validation Quantities

1,000 of E=10 TeV and random , (= neutral geantinos since physics/field off)

Material Budget (ROOT tree, histos, or ascii file)

For each Geant4 step of each muon:• Accumulated track length, volume name, volume copy number, accumulated material budget (Number of radiation lengths), material radiation length.At the end of track:• Accumulated material budget.


Field Validation

Checks the tracking in the CMS magnetic field. The test compares thedeviation at the end of the track in position and direction.

400 single muon events in four groups of 100 events with different energies: 1, 10, 100, 1000 GeV. The muons behaves as charged geantinos (physics is off).

Change in track angle, momentum, kinetic energy.

Sample

Validation Quantities


Global ValidationSub-system packages: dedicated validation tests for individual sub-systems. Geometry sub-set, field off.

Global package: validates entire detector with real field, using pp physics samples. For example, min-bias.

1. Monte Carlo

Number of vertices from Geant4Number of tracks from Geant4Number generated particlesPosition (x,y,z) of each Geant4 vertexpT of each Geant4 trackEnergy of each Geant4 track

2. Electromagnetic Calorimeter

Number of Ecal hitsEnergy of each Ecal hitTime of flight for each Ecal hitGlobal of each Ecal hitGlobal of each Ecal hitNumber of preshower HitsEnergy of each preshower hitTime of flight for each preshower hitGlobal of each preshower hitGlobal of each preshower hit


Global Validation (II)3. Hadronic Calorimeter

Number of hitsEnergy of each hitTime of flight for each hitGlobal of each hitGlobal of each hit

4. Tracker

Number of Pixel hitsGlobal of each Pixel hitGlobal of each Pixel hitTime of flight of forward Pixel hitsTime of flight of barrel Pixel hitsGlobal R of barrel Pixel hitsGlobal Z of forward Pixel hitsNumber of Silicon hitsGlobal of each Silicon hitGlobal of each Silicon hitTime of flight of forward Silicon hitsTime of flight of barrel Silicon hitsGlobal R of barrel Silicon hitsGlobal Z of forward Silicon hits

5. Muon

Number of hitsGlobal of hitsGlobal of hitsTime of flight for DT hitsGlobal R of DT hitsTime of flight for CSC hitsGlobal Z of CSC hitsTime of flight for RPC barrel hitsGlobal R of RPC barrel hitsTime of flight for RPC forward hitsGlobal Z of RPC barrel hits


Summary & OutlookCMS simulation validation suite for hit derived quantities is operational – being ported to the CMSSW framework

• Iterate on validation quantities• Optimize sample types, size, tune tolerance values

In progress:

• Expand Physics Validation Suite to include Digis (pulse shape, pedestals, gains)

In the future:

• Incorporate reconstructed physics objects: jets, e, ,

CHEP06, Mumbai-India, Feb 2006V. Daniel Elvira 1 The CMS Simulation Validation Suite V. Daniel...

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