Simulations and Software

CBM Collaboration Meeting, GSI, 17 October 2008

Volker Friese

Simulations

Software

Computing

Volker Friese CBM Collaboration Meeting, 17 October 2008 2

Simulations

• Key observables well in hands; many studies ongoing

– to be ctd. with ever more realistic detector descriptions

• Sufficient information delivered for start of detector engineering

• Trigger considerations (charmonium, open charm) under way

• Look into running at SIS100: promising

• First steps to study so far uncovered topics:

– centrality determination

– event plane resolution

– flow

– TOF with start detector

Volker Friese CBM Collaboration Meeting, 17 October 2008 3

Software status

• Software development is still rapid

• Focus shifted from detector description to reconstruction / analysis

• Needed / ongoing

– consolidation / cleanup

– control

– quality assessment

– documentation

Volker Friese CBM Collaboration Meeting, 17 October 2008 4

Tools

• Event generators:

– Strategy of adding signal to background event (UrQMD) not valid for low-multiplicity events (e. g. p+C). Look for realistic generators for such events.

– For PSD studies: proper fragmentation model needed. SHIELD is ok, but does not run with TGeant3

• MC engines:

– TGeant3: our baseline. G3 not developed any longer

– TGeant4: works (some problems), but physics list to be determined

– TFluka: not operational.

– Native Fluka used for radiation level studies

Volker Friese CBM Collaboration Meeting, 17 October 2008 5

Detector Description

System MC Geometry Digitisation

MVD MonolithicDigitiser

charge sharing,clustering

STSSegmented,

passive materialsDigitiser,

charge sharing,clustering

RICH Passive materials HitProducer

MUCH Segmented Digitiser,charge sharing,clustering

TRD Segmented HitProducer

TOFSegmented,

passive materialsHit Producer

(advancd)

ECAL Segmented Shower model

PSD Segmented Digitiser

Volker Friese CBM Collaboration Meeting, 17 October 2008 6

Software status

• Geometrical description fairly well advanced; supports etc. mostly missing

• Detector response models ("digitizer") implemented for almost all subsystems

• Parameters taken from literature or educated guesses

• Have to be tuned to detector tests / prototype measurements

Volker Friese CBM Collaboration Meeting, 17 October 2008 7

Against all odds...

Test beam time, September 2008

First data taking with untriggered, free-streaming DAQ

Worked in principle (many open questions yet)

First glimpse on such a data stream

Volker Friese CBM Collaboration Meeting, 17 October 2008 8

Towards modeling the data stream

eventwise

Event Generator

MC Transport

Reconstruction

Digitisation

Analysis

eventwise

Experiment

eventwise

Reconstruction

Analysis

free streaming

Event builder

eventwise

Event Generator

MC Transport

Event builder

Digitisation

Reconstruction

eventwise

free streaming

Volker Friese CBM Collaboration Meeting, 17 October 2008 9

Online and Offline

• Online reconstruction (L1 / Hough) will not be implemented on "normal" architectures

• Implementation on FPGA / multi-core requires dedicated programming languages

• Up to now, models for the algorithms are implemented in CBMROOT. Will not continue to be so (?)

• Integration / connection of framework and online software to be rethought

Volker Friese CBM Collaboration Meeting, 17 October 2008 10

Computing

• CBM computing model to be worked out

• Some facts:

– 1 TB/s from detector

– archival rate 1 GB/s 5 PB per CBM year

• Online processing will (most probably) be on site

• Reconstruction can in principle be distributed

• Analysis should be distributed

• Can full reconstruction be done online?

• If yes, will raw data be stored?

• Connections to FAIR computing concept?

Volker Friese CBM Collaboration Meeting, 17 October 2008 11

FANCy

Proposal submitted September 2008CBM is used as showcase

Volker Friese CBM Collaboration Meeting, 17 October 2008 12

CBM GRID

• Aims:

– facilitate simulations by use of ressources other than GSI

– enable larger statistics: 105 events 107 events

– gain experience for using distributed computing for real data processing

• Status:

– Central services installed at GSI, tests ongoing

• Perspectives:

– 2008: Small test grid (3-4 sites), test data challenge

– 2009: Production mode

CBM Grid Structure (work started 2008)

GSI

so far 1 test site at GSI on a virtual machine

Oracle DB ?

K. Schwarz, F. Uhlig

running site services @ GSI

• Computing Element (CE)

• Storage Element (SE)

• Packman (for installing experiment software on the Grid (CBMRoot)

• FTD (File Transfer Daemon) (intersite transfer)

– transfer protocoll: xrootd

• first jobs have run successfully !!!

• first job output has been stored successfully at CBMGrid Storage Elements

K. Schwarz, F. Uhlig

CBMGrid central services

upcoming sites:GSI LSF, Aman, Dubna, Calcutta, NIHAM, ...

K. Schwarz, F. Uhlig