Java Reconstruction and Analysis for a Linear Collider Detector

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Java Reconstruction and Analysis for a Linear
Collider Detector

• Tony Johnson
• SLAC/Babar Tutorial
• November 11th 1999

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Contents

• The Java hep.lcd framework for LC physics studies
• Overview
• Why Java?
• Fast MC
• Tracking Reconstruction
• Cluster Finding
• Java Analysis Studio
• Distributed Physics Analysis
• Java Performance
• Conclustions - How to try it out!

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LCD Road Map
Yellow Java hep.lcd package
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What is hep.lcd?

• A Java Framework for
• Running Reconstruction and/or FastMC
• Analysis of LCD data from Stdhep, Gismo, FastMC
• A Tool for
• Rapid Development of Reconstruction Algorithms
• A Suite of Physics Analysis Tools
• Histograming, Event Display, Jet Finding, etc.
• Emphasis on Flexibility and Extensibility
• Typically provide multiple reconstruction
  algorithms
• Support for Large Small ...
• Can be used standalone or inside Java Analysis
  Studio

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Why Java?

• Modern Object-Oriented language
• Easy to learn and use
• No backwards compatibility with C etc.
• No pointers, memory leaks
• Syntax very similar to C, but without many of
  the more obscure, less useful features
• Very Suitable for Rapid Prototyping
• Powerful built-in utility libraries
• Fast compiler, no link step, dynamic loading
• No problems with porting code to new platforms
• Can use Java Analysis Studio for interactive
  analysis
• Bottom Line
• If you know C Java will be familiar and a
  refreshing change
• If you dont yet know C Java is an excellent
  stepping stone

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Java package hep.lcd

• Reconstruction Processors
• Track finder track fitter
• Several clustering algorithms
• Parameterized MC Processors
• Can read generator output (StdHEP) or Gismo
  output
• Track and Cluster smearing
• Analysis Utilities
• Event Shape Thrust utilities
• Jet finders Jade, Durham
• Histograming
• Event Display
• Simple 2D Event display currently

• Framework
• Driver framework
• interactively control
• calling of processors
• debugging/histograming
• Parameter (Constant) access
• driven by detector geometry
• MC event input (StdHEP format)
• IO system based on Java IO
• random access files allows efficient access to
  subset of data
• Can be run inside JAS or standalone

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Track Finding/Fitting

• Track Reconstruction
• Track Finding uses M.Ronans (TPC) pattern
  finding
• Tuned for Large Small detector
• Track Fitters
• SLD Weight Matrix Fitter
• Kalman Filter coming soon
• Fortran not Java, will need native library for
  each platform
• Can do Single Detector or Combined fit (e.g.
  VTXTPC)
• Hit Smearing/Efficiency (since Gismo gives
  perfect hits)
• Random Background overlay
• Whats still needed
• More Track Finding Algorithms (Cheater,
  Projective Geometry)
• End Cap tracking

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Cluster Finding

• Three Clustering Algorithms Currently Implemented
• Cluster Cheater (uses MC truth to cheat)
• Simple Cluster Builder (Touching Cells)
• Radial Cluster Builder
• All algorithms tend to produce many very low
  energy clusters - important to set sensible
  thresholds
• Still Needed - Cluster Refinement Stage
• Combine HAD EM clusters
• Endcap Barrel overlap region
• In Progress - Track Cluster Association
• Initial Implementation Done by Mike Ronan
• Output Format defined by Gary Bower
• Need to Extend Definition of Clusters
• Directionality, Entry point to calorimeter

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Fast MC

• Simple parameterized MC
• Allows analysis directly from generator output
  without using full Gismo simulation
• Produces same event format as Gismo
• same analysis can be run with FastMC or Gismo.
  Can read StdHEP (generator files) or Gismo output
• Produces tracks from MC particles based on
  parameters provided by Bruce Schumm
• Produces Tracks Error Matrices
• Output compatible with Output from Full Recon
• No Calorimeter Simulation at Present

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Physics Utilities

• Physics Utilities
• 4-vector, 3-vector classes
• Event shape/Thrust finder
• Jet Finder
• Jade and Durham algorithms implemented
• Extensible to allow implementation of other
  algorithms
• Histograming (from Java Analysis Studio)
• Event Display
• Suitable for debugging reconstruction and
  analysis
• Plan to use Wired for full 3D support in future
• Particle Hierarchy Display
• Contrib Area
• Analysis Utilities and sample analyses provided
  by users

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Event Display
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Event Display
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Event Display
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Event Display
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Documentation

• http//www-sldnt.slac.stanford.edu/jas/documentati
  on/lcd/

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Access to Code - CVS

• Code recently moved to CVS for universal access
• Most development currently done on NT
• Now Unix development should be easy too
• Browse CVS repository on Web
• Connect with you favorite CVS client
• protocol pserver
• server sldl1.slac.stanford.edu
• cvsroot /nfs/slac/g/jas/lcdroot
• userid anoncvs
• password jascvs
• module lcd

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Java Analysis Studio

• Set of experiment independent analysis tools for
  event oriented (High Energy Physics) data
• Data Access classes provide access to many common
  HEP data formats
• Histogram/Scatterplot Accumulation Manipulation
  Classes
• Plot Display classes
• Lightweight framework for users to create physics
  analysis applications in Java.
• Tools work alone, in combination, or within
• Java Analysis Studio GUI which gives
• Integrated editor and compiler
• Efficient access to local and remote data
• Extensibility via Plug-ins, Fitters, Functions etc

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GUI makes getting started easyWizards guide
beginners
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Built in Editor and Compilerfor writing analysis
code
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Histogram and Scatterplot displayInteractive
Fitting and Rebinning
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GUI can be extended to addexperiment specific
features
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Distributed Data Analysis with JAS

• With many different simulated detectors and many
  physics processes, total MC data sample is large
• JAS has built in support for efficient
  distributed physics analysis

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Data Repository at Penn

• LCD has set up central data repository at UPenn,
  accessible from anywhere

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Is Java fast Enough for HEP offline?

• Current (266Mhz PII, JDK 1.1.7)
• Clustering .6 secs/event
• 13.5 Million Calorimeter Cells
• Fast MC 6 ms/event
• Track Finding Fitting 5secs/event
• Very competitive with C/Root implementation
  (where they exist)
• Will get even better!!!
• JDK 1.2, HotSpot - Run-time optimization
• In real life may be faster than C
• Better, cheaper performance analysis tools
• Java encourages lightweight, module interfaces
  which promote efficient coding styles
• People time is what really matters

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Reconstruction Speed
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Example of Using Track Recon.
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To Do List

• Finish integration of MCFast Kalman filter
• Support for merging signal/backgrounds
• Additional Track Finders (projective, cheater)
• Improved Cluster Description
• Track/Cluster Association
• Cluster Refinement
• Vertex Finding code (based on ZVTop?)
• WIRED Event Display
• Support for SIO format reading/writing
• Switch to XML based geometry description
• Small Angle Tracking
• Reference Analyses

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Try it out!

• Come to the tutorial this afternoon
• Works on Windows (95/98/NT or Unix (Linux,
  Solaris,) or Other
• Online tutorial available
• Suitable for complete beginners
• no knowledge of Java or JAS assumed
• starts with instructions on downloading and
  installing
• Shows simple sample analysis jobs
• http//www-sldnt.slac.stanford.edu/jas/documentati
  on/lcd/
• JAS Home Page
• http//www-sldnt.slac.stanford.edu/jas

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New Features in JAS 2.0

• Many bug fixes - Printing Works - Save Histograms
  as GIFs
• Easier to install LCD extensions
• no need to edit jas.ini
• Support for logging output to a file
• Supports 2D Binned Histograms (in addition to 1D
  Histograms and Scatter Plots)
• Standalone jobs can save histograms (for later
  viewing in JAS)
• Local jobs can append multiple datasets
• Built-in LCD documentation/help
• Gotchas for LCD users
• Must use JAS 20 version of lcd.jar (in lcd
  download area)
• Cannot connect to old servers (SLDNT0 OK)

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JAS 2.0 Now available from JAS website