# Presentation: 106480

## STAR simulations 

- GSTAR framework
- OO geometry/event model
- NOVA components

- STAR detector at RHIC

## GSTAR

- STAR simulation framework since 96
- has a hierarchical design  to clearly separate user code from implementation details
- has improved memory management
- elastic ZEBRA (using malloc)
- no limits on number of tracks, vertices, hits etc    (apart from physical memory limits)
- has built-in interfaces to implementation
- Geant3/PAW,  MySQL,  ROOT

## Hierarchical design

- Open System Interconnection (OSI) model   as example: functionality in term of layers
- basic (physical) layer - platform dependant code, system libraries,graphics etc
- low (logical) layer - ZEBRA, DZDOC,HIGS
- upper (transport)  - G3, Paw+Kuip, DB, ROOT
- system (session) - AGI,  ROOT accessors
- user (application) - modules in F, AGI, C++

## STAR geometry

- Formalized description in specification language, including hits and DB access
- Many developers, very detail geometry (almost 2,000 different volumes)
- Altogether less then 8000 lines including field parameterization , easy to read
- No step routine is needed in most of the detectors,  no “if statement” problem

## GSTAR performance

- Fast enough - 30 min/10,000 particles, with a general 1 MeV cuts
- Calorimeter cuts tuned with test beam date down to 50 KeV
- Interfaced to all event generators
- Robust and well debugged production tool

## Requirements for rOOt interface

- Flexible, expandable access to geometry  objects from reconstruction program
- Modern visualization and navigation
- Access to hits from  a C++ code  as  if they were normal C++ objects
- fun, and even more fun

## New elements

- Initially missing elements
- Geometry navigator - trivial
- Geometry decoder - not so trivial, but feasible
- Volumes and positions separately - TVolume
- Volumes as position container - TDataset
- Hit navigator - trivial
- Hit presenter - StGeantHits

## G3 geometry model

- TDataset

- TVolume

- TVolumePosition

- TVolumePosition
-  list

- TVolumeView

- TShape

- StGeant

- TNode

- TVolumeView

- ctor

- ctor

## View as in G3

## Geant Hit Access Class

**class TPoints3DABC**
**(*****from ROOT G3D*****)**

**StGeantHits3D**

**StGeantHits()**
**...**
**GetNextHit(Int_t indx)**

- GZEBRA

**aghitget()**

**aghitset()**

## OpenGL viewer

## Star Event Display

## NOVA Architecture

## Dynamic Object Broker

- Central Database Server

- Middleware Services

- Remote Application Clients

- Parameters Repository

- Object
- Request
- Broker

## STARgeometry

- Modules: 14
- Structures: 34
- Instances: 45
- Parameter values: 841

## Database Browser

- Versioned geometries

## Simulation Production

- Multilayer model (NOVA component)
- universal Simulators (smart cockroaches)
- common Dispatcher - token coordinator
- output/QA Filter
- HPSS Sinker
- Open system - extendable functionality

## Production bandwith

- simulation - 50 ev/day/processor - scales well
- dispatcher - scalability tested up to 10K ts/day
- filtering - local disk I/O - no limit at 1 TB/day
- sinking - stable up to 1 GB/day

##  Conclusions

- GSTAR is a stable production tool
- G3 geometry is based on MySQL DB
- G3 geometry is available as ROOT classes
- Looking for a G4 interface