STARSTARSimulation OverviewSimulation Overview

Maxim PotekhinMaxim PotekhinSTAR Collaboration MeetingSTAR Collaboration Meeting

BNLBNL February 28, 2003February 28, 2003

OverviewOverview

STAR simulation infrastructure components STAR simulation infrastructure components

Current projects Current projects

Development areas, or where we are and where Development areas, or where we are and where we want to be we want to be

Simulation infrastructure componentsSimulation infrastructure components

Main simulation tool: STAF/GSTARMain simulation tool: STAF/GSTAR– based on PAW and GEANT 3.21based on PAW and GEANT 3.21– dynamic loading of user libraries on demanddynamic loading of user libraries on demand– high degree of interactivity, with full scripting capabilityhigh degree of interactivity, with full scripting capability– output in ZEBRA formatoutput in ZEBRA format– persistent data, such as geometry, in the outputpersistent data, such as geometry, in the output– dataset management currently done via entries in the catalog filedataset management currently done via entries in the catalog file

Translation layer: g2t* Translation layer: g2t* Detector Geometry Description Detector Geometry Description Event Generators Event Generators Simulation Data Simulation Data DocumentationDocumentation– web pages being updatedweb pages being updated

Translation layer: g2t*Translation layer: g2t*

provides mapping of the native GEANT structures and variables to those provides mapping of the native GEANT structures and variables to those used in reconstruction. Maintenance requires expert knowledge of GEANT.used in reconstruction. Maintenance requires expert knowledge of GEANT.

Code examples:Code examples:

Do While (G2R_GET_HIT('emc') .eq. 0)Do While (G2R_GET_HIT('emc') .eq. 0)

g2t_emc_hit(i).de = Elosg2t_emc_hit(i).de = Elos

g2t_emc_hit(i).volume_id = volumeg2t_emc_hit(i).volume_id = volume

enddoenddo

section = numbv(1+shift) ! ECVOsection = numbv(1+shift) ! ECVO

phi_30d = sector_hash(numbv(2+shift),ib) ! EMODphi_30d = sector_hash(numbv(2+shift),ib) ! EMOD

zsubsect = numbv(3+shift) ! ESEC (no readout)zsubsect = numbv(3+shift) ! ESEC (no readout)

zsublayer = numbv(4+shift) ! EMGT (no readout) zsublayer = numbv(4+shift) ! EMGT (no readout)

volume_id = 100000*rileft+1000*(5*(phi_30d-1)+phi)+10*eta+sectionvolume_id = 100000*rileft+1000*(5*(phi_30d-1)+phi)+10*eta+section

Detector Geometry DescriptionDetector Geometry Description

Number of detector subsystems: 18Number of detector subsystems: 18

Custom macro “geometry language” (*.g files)Custom macro “geometry language” (*.g files)– based on the obscure Fortran preprocessor called Mortranbased on the obscure Fortran preprocessor called Mortran– ideally suited for application-specific Fortran code structuringideally suited for application-specific Fortran code structuring– in many cases, helps circumvent limitations of Fortranin many cases, helps circumvent limitations of Fortran– can be of help with the GEANT learning curvecan be of help with the GEANT learning curve– has been successfully used in a number of projectshas been successfully used in a number of projects

11,000 lines of geometry code, largely user maintained11,000 lines of geometry code, largely user maintained

As previously mentioned, volume maps (not part of the geometry per se) are As previously mentioned, volume maps (not part of the geometry per se) are maintained separately in “g2t” files.maintained separately in “g2t” files.– May or may not be user maintainable.May or may not be user maintainable.

Detector Geometry DescriptionDetector Geometry Description

Code example:Code example:

Block SVTT is the mother of all SVT volumesBlock SVTT is the mother of all SVT volumes

* * Material AirMaterial Air

Attribute SVTT seen=0 colo=1Attribute SVTT seen=0 colo=1

Shape TUBE Rmin=svtg_RsizeMin, Rmax=svtg_RsizeMax, dz=svtg_ZsizeMaxShape TUBE Rmin=svtg_RsizeMin, Rmax=svtg_RsizeMax, dz=svtg_ZsizeMax

* End rings to support the ladders:* End rings to support the ladders:

**

Create SIRP " inner end ring polygon piece " Create SIRP " inner end ring polygon piece "

Position SIRP Z=serg_EndRngZm+serg_EndRngTh/2 AlphaZ=22.5Position SIRP Z=serg_EndRngZm+serg_EndRngTh/2 AlphaZ=22.5

Event generatorsEvent generators

Option to either generate events “on the fly”, or feed the Option to either generate events “on the fly”, or feed the GEANT simulator from a pre-fabricated event file.GEANT simulator from a pre-fabricated event file.

Currently usedCurrently used– Hijing, moving from 1.33 to the newer 1.382Hijing, moving from 1.33 to the newer 1.382

expertise provided by Ron Longacreexpertise provided by Ron Longacre

– Pythia 6.203Pythia 6.203– Experimenting with Nexus: Ron Longacre and Gael RenaultExperimenting with Nexus: Ron Longacre and Gael Renault

Simulation dataSimulation data

Simulation output: ZEBRA filesSimulation output: ZEBRA files– can be re-opened and inspected with STAF can be re-opened and inspected with STAF

(geometry, hits, etc)(geometry, hits, etc)– serve as input for the reconstruction chainserve as input for the reconstruction chain– large dedicated holding area for simulation fileslarge dedicated holding area for simulation files

HPSS population:HPSS population:– approx. 180 datasets, 18000 filesapprox. 180 datasets, 18000 files– catalog (maintained by Lidia)catalog (maintained by Lidia)

Current projectsCurrent projects

Monte Carlo dataset productionMonte Carlo dataset production– Hijing 1.33 (done)Hijing 1.33 (done)– Hijing 1.382 (in progress)Hijing 1.382 (in progress)– produced at RCF and PDSF (Eric Hjort)produced at RCF and PDSF (Eric Hjort)– data RCFdata RCFPDSF transfer scheme (HRM based) is PDSF transfer scheme (HRM based) is

being worked on (Eric)being worked on (Eric)

STAF/GSTAR application support STAF/GSTAR application support Ongoing STAR geometry support Ongoing STAR geometry support Event generator support (new versions etc)Event generator support (new versions etc)

New geometry description? New geometry description? Documentation (Olga Barannikova)Documentation (Olga Barannikova)

STAF application supportSTAF application support

Maintenenance of codebaseMaintenenance of codebase

Keeping up with external libraries and compiler Keeping up with external libraries and compiler versionsversions

DocumentationDocumentation

STAR geometry supportSTAR geometry support

STAR is an experiment undergoing constant upgrades. STAR is an experiment undergoing constant upgrades. This requires timely updates of the geometry definition This requires timely updates of the geometry definition files and other related configuration data (g2t).files and other related configuration data (g2t).

– Endcap EMC (Jan Balewski)Endcap EMC (Jan Balewski)– TOF trays (Frank Geurts)TOF trays (Frank Geurts)

Correcting geometry inaccuracies. Recently:Correcting geometry inaccuracies. Recently:– FTPC (extraneous structure elements)FTPC (extraneous structure elements)– Endcap EMC volume Id’s (Jan)Endcap EMC volume Id’s (Jan)– material distrribution in SVT (Ian) material distrribution in SVT (Ian) – BBC volume hierarchy (Joanna, Akio)BBC volume hierarchy (Joanna, Akio)

Example: SVT studyExample: SVT study

Based on an observation by Ian Based on an observation by Ian Johnson, about mismatch of the Johnson, about mismatch of the number of photon conversions in number of photon conversions in the detector, in the experimental the detector, in the experimental data vs MC.data vs MC.

– extra material in localized areas extra material in localized areas of SVT, unaccounted for in the of SVT, unaccounted for in the geometry modelgeometry model

– Complex design of the SVT Complex design of the SVT feeds and support structures feeds and support structures makes geometry modeling hard, makes geometry modeling hard, despite high level of detail despite high level of detail already implemented in the already implemented in the model.model.

Example: SVT studyExample: SVT study

Using photon conversions to probe Using photon conversions to probe material density in the detectormaterial density in the detector

STAR simulations development areasSTAR simulations development areas

Documentation (something that can always be Documentation (something that can always be improved)improved)

Dataset catalogingDataset cataloging

Further productization of STAF. Platforms other Further productization of STAF. Platforms other than Linux/gcc.than Linux/gcc.

New tools for geometry description? New tools for geometry description?

New tools for geometry description?New tools for geometry description?

Current geometry macro languageCurrent geometry macro language– Works extremely well for GEANT 3.21 target languageWorks extremely well for GEANT 3.21 target language– Is based on the technology with scarce knowledge baseIs based on the technology with scarce knowledge base– Hard (or impossible) to extend to other applications Hard (or impossible) to extend to other applications

SVT Tracking software? Reco? G4? Event display?SVT Tracking software? Reco? G4? Event display?

Current lack of unitary geometry description for both Current lack of unitary geometry description for both Monte Carlo and reconstruction software is a liabilityMonte Carlo and reconstruction software is a liability– significant complexity of bothsignificant complexity of both– difficulty of reconciliation, no handshakedifficulty of reconciliation, no handshake

New tools for geometry description?New tools for geometry description?XML technology studied in R&D projects for ATLAS and XML technology studied in R&D projects for ATLAS and ALICE (and some other experiments)ALICE (and some other experiments)– Qualified successQualified success– Detailed DTD worked outDetailed DTD worked out– Parameter blocks implementedParameter blocks implemented– Difficulties encountered in the implementation of programmatic Difficulties encountered in the implementation of programmatic

constructs (such as loops and formulas) in geometry descriptionconstructs (such as loops and formulas) in geometry description

XML proXML pro– Well understood technology with vast knowledge baseWell understood technology with vast knowledge base– Integration with databases etcIntegration with databases etc– Variety of well documented and supported tools, Java classes in Variety of well documented and supported tools, Java classes in

particularparticular– Platform neutral, i.e. not tied to a particular target languagePlatform neutral, i.e. not tied to a particular target language

XML contraXML contra– lack of demonstrable success (commissioned production app) in lack of demonstrable success (commissioned production app) in

any collaboration so farany collaboration so far