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Simulation and Tools

Ties Behnke, DESY

Summary of the simulation sessions

At this conference: 4 sessions (one combined with Loop Verein)

Shows healthy interest in the subject Shows healthy number of people working with simulation tools

This talk: as requested, no traditional summarybut rather a view of the field and a (somewhat personal) perspective

Areas covered in the session:

Simulation proper Reconstruction algorithms and tools Generators (see separate generator summary)

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A Survey: where are we

Legacy softwareLEPHERA ...

New developmentsJASLCD

GEANT3 GEANT4

BRAHMS MOKKA, JupiterLCDG4, ...

The Linear Collider Community:experimentaliststheoristssoftware “nerds”PAW addicts.....

C++FORTRANJAVA

very few workfull time on this!

SNARKREPLIC

VERTIGO

PatR

ec

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Requirements

Software for LC studies needs to be

simple portable cheap (no commercial packages, if at all possible) rely on few number of well defined, easily accessible packages

but at the same time provide full functionality ... ???

make involvement of community simple remain open, close as few doors as possible (language...) keep it simple work together

probably no “grand solutions” (they tend to be complex) concentrate on well designed simple interfaces don't be religious about anything

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Full Simulation

GEANT4 accepted as de-facto standard

GEANT3 still widely used (and still very powerful in many respects)

But: the transition to GEANT4 is on-goingvalidation of GEANT4 is happeningThe user community is growing

GEANT4 is a toolkit (contrary to GEANT3, which was a “way-of-life”)

many open auxiliary questions: geometry definitionpersistencygraphicsuser interaction

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Fast Simulation

Standard fast parametrised simulations (SIMDET, QuickSim) have been very powerful

A move towards non-parametrised, but still fast MC is visible: allow detector optimisationallow fast changes of parameters (at least some)

Lelaps (C++), SGV (Fortran) exist and work and are being used

An event simulated in LeLaps:hits in trackerhits in calorimeter

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(Full) Simulation Frameworks

MOKKA: developed since 99

geometry system (mysql database) infrastructure CGA (common geometry access) model

LCDG4: developed since 03 (based on earlier version)

xml based geometry model (simplified geometry at the moment) infrastructure persistency model

Jupiter:

uses root as frame and for persistency, GUI geometries in C++ (ParameterList classes to isolate geometry)

BRAHMS:

GEANT3 based full simulation and reconstruction package: still the mostcomplete package available

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Commonalities

while the frames are different

the problems are the same!

definition of geometries (accessible, sharable, transportable) definition of data model beyond pure simulation many detailed technical questions (e.g., MC tree treatment, etc etc)

Lots of room for collaboration

Lots of NEED for collaboration

compared to the situation one year ago, there is significant progress in the migration towards GEANT4: encouraging!

Plan: formulate a document with requirements and requested features for a full MC frame, hopefully with inter-regional agreement

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Architecture

proposed architecture of a simulation / reconstruction system

Generator

geometry

Analysis

Recon-structi

on

Simulation

Java, C++,

FortranGeant3, Geant4

Java, C++,

Fortran

Java, C++,

Fortran

Data model / persistency

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Data model/ Persistency: LCIO

LCIO (Linear Collider Input Output):

proposal for a common data model and persistency scheme developed in collaboration between SLAC/ DESY/ LLR

design goals:

simple, lightweight package data model for LC studies, expandable to adopt to evolving needs supports broad set of platforms and environments

support for C++ - JAVA - FORTRAN

hit model reconstructed quantities model

abstract “particle” model

project started: Prague 2002first beta release: Amsterdam 2003first production release: end 2003first complete release: LCWS 2004

project started: Prague 2002first beta release: Amsterdam 2003first production release: end 2003first complete release: LCWS 2004

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Status

Beta release of first complete implementation (including reconstructed quantities)available

Many authors of LC packages are adopting LCIO:

MOKKA (LCIO compliant)LCDG4 (soon to be LCIO compliant / merging with MOKKA)JUPITER (expressed plans to become LCIO compliant)

LeLaps (LCIO compliant)BRAHMS (LCIO compliant)SIMDET (plans announced to be LCIO compliant)

LCIO developments / status:

http://lcio.desy.dehttp://forum.linearcollider.org

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Generators

Generators are crucial (of course) for a successful study

Flexibility is essential: legacy generators, modern generators, very modern generators. ...

sensible proposal: use stdhep as common interface between generators and simulation, support ascii and binary format

large activity in the generator community:

new complete packagesreengineering of known packages (e.g. HERWIG++, ...)more and more many fermion final state MC available

from a user perspective: it would be nice to agree on a generic way to handlebeam conditions (e.g. crossing angles, ...)

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Reconstruction

Lots of work on individual reconstruction tools is ongoing

Tracking studies/ pattern recognition developments

Algorithms developments for ParticleFlow

merging algorithms clustering algorithms particle ID algorithms vertexing tools detailed detector modeling

(noise etc) .....

Currently no coherent frame exists for these developments

study of the dependence of E-resolution on noise in the cal

test beam and prototypeefforts are really pushingthe development!

test beam and prototypeefforts are really pushingthe development!

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Reconstruction Example

Example:

particle flow / calorimeter reconstruction

many groups do similar studies

NIU Oxford UTA DESY ITEP .... (apologies if I forgot you)

Sharing and comparing of results is very important and becomes much simpler if we speak a common language.

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Reconstruction: what's there

RERECO: full reconstruction (tracking, calorimeter, particle flow) in FORTRANLCIO compliant (at the moment the only complete reconstruction available)

Several partial packages (clustering, particle flow, hybrid Monte Carlo reconstruction, LCD analysis framework (JAVA),root based analysis frames,...)

The Goal:

provide a simple framework for reconstruction and analysis modulesto plug into

provide interfaces to standard packages like WIRED (event Display) etc. The language of the reconstruction code should not be a central issue

The Dream:

make samples of fully reconstructed events available to the international user community through a “GRID” like framework

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Reconstruction

Goal: integrate reconstruction tools as much as possible into the LCIO data model

minimize dependence on external packagesadopt the data model (which may need to be extended)

advantages:

ease of exchanging of tools (possibility of comparisons!)become more flexible save time and effort in the medium term

In my view the advantages of a common API are far larger than the disadvantages of a “simplistic” system like LCIO

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The Future

The collaborative model used for LCIO worked very well

We should continue to develop this for other tools:

Simulation Reconstruction Analysis Tools

At this meeting: discussed and started even closer coherent development of GEANT4 frameworks

Communication is very important:

common WEB based Forum to exchange news, ideas etc

http://forum.linearcollider.org

We encourage everyone to use this forum. New forums can be addedif required. This can be a very powerful tool!

common WEB based Forum to exchange news, ideas etc

http://forum.linearcollider.org

We encourage everyone to use this forum. New forums can be addedif required. This can be a very powerful tool!

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Conclusion

Significant progress during the last year:

LCIO is being adopted by more and more groups

GEANT4 frameworks move to be real frameworks

The user community is growing

There is lots of progress in developing reconstruction algorithms

There are still significant problems:

Geometry definition is still an issue

modern reconstruction frameworks do not exist

personpower (very few developers for general tools) does hardly exist

WE NEED YOU AND YOUR KNOW HOW TO MAKE PROGRESS AND SUPPLY THE TOOLS NEEDED BY THE COMMUNITY!

http://forum.linearcollider.org

WE NEED YOU AND YOUR KNOW HOW TO MAKE PROGRESS AND SUPPLY THE TOOLS NEEDED BY THE COMMUNITY!

http://forum.linearcollider.org