Status of the OPERA simulation software

• Introduction: – generator, simulation, digitization status

• Recent development in OpRoot – detector geometry implementation– Tracking of the tau

• Conclusions

D.DuchesneauLAPP, Annecy

OPERA collaboration meeting May 19th, 2003

NEGN / Jetta OpTreeConvertOpRoot

Inputs for track reconstruction

Physics ...

Simulation Digitisation

Reconstruction

Software chain: Actual development: main goal is to provide a working chain from

Event generation to the digit level for production:

Detector simulation relies on Geant 3 in the OpRoot framework

Hitsroot

OpDigit

Hitsroot

ASCIIbeamfile

digitsroot

TTree structure TFolder structure

OpDigit nearly ready!Complete chain will be finalized in about 2 weeks

Evt generator

Event generator: NEGNOPERA adaptation of the NOMAD event generator (Dario)

Official release: v1.00 on april 24th 2003 available on LXPLUS, standalone package

Characteristics: • DIS interactions described by modified LEPTO6.1• QE process: based on Llewellyn-Smith formulation• RES process: based on Rein & Seghal model• Coherent interactions• Hadronization according to JETSET 7.4 retuned with Nomad data

Includes:Neutrino DIS, QE and Resonant processesOptions: Nuclear interactions, …..

READY for production. The program produces standard OPERA event beamfiles.

Simulation Software: OpRoot Detector simulation relies on Geant 3 in the OpRoot framework

Major changes done recently consist of: •implementing and uniformising all the sub-detector geometry descriptions (odd files)•check the compatibility between the different OPERA parts (volume position etc…)•Tracking of short lived particles like the tau in the emulsion films•Update the hit structures to keep mother and primary references

Version 5 READY for production. It produces root trees event by event with hits for each subdetector .

DTLY

OPERA geometrical tree in OpRoot 48 different volumes

All the positioning along the Z axis is based on this drawingRef: Frascati drawing 12/11/02

Z (cm)-823.4 -452.62 44.88 104.4 etc……

For the target section: •the support structure for the Scintillators and the bricks are not described (2nd order…)

For the spectrometer section:•Only the SRPC chambers include supporting structures, screws, profiles, spacers….•The XPC and Drift tubes have no support described

Geometry description in this OPERA implementation

From OpRoot

the distances between emulsions layers and scintillator strips are based on numbers available in february 2003.

TT:

•the CS emulsion layer position takes into account additional separation due to packaging , CSS etc… = 0.2766 cm distance with last emulsion

•Ref: Document LAPP, H. Pessard et al., january 10th 2003,

Emulsion bricks:

Spectrometer part:

Uniform B = 1.55 T

Spectrometer RPC planes: 21 chambers / plane

screws

spacers

8.76 m

7.98

m

Drift tube planes: 4 layers of 192 tubes

Tube: outer radius 1.85 cminner radius 1.7 cmlength: 8m

Wire diameter: 60m

2.03 cm

5.67 cm

4.2 cm

Spectrometer XPC planes: 21 chambers / plane

spacers

8.75 m

8.06

m

To verify: position of the second XPC plane? Before or after the DT plane?

OpRoot final setup:Hits are saved along particle tracks in active volume

Scintillators, DT, XPC, RPC: 1 hit per strip or gas volume per track middle point between entrance point

and stopping or exiting point

Emulsions:

2 hits per emulsion layer per track entrance point and stopping or exiting point

Hit visualization: interaction with

emulsions

SRPC

Drift tubes

XRPC

Scintillators

Hit description: (example)

Scintillators: 1 hit per strip per track

•fX, fY, fZ coordinate of the hit•fPartPx, fPartPy, fPartPz Momentum of the particle at the hit position•fEdep energy loss•fPartId Pdg number of particle•fParMass Mass of the particle•fPrimary Id of the primary particle•fMother Id of the mother particle•fTrack track number in Geant•fSciSM SuperModule number•fSciWall Wall number•fSciBox Scintillator module•fSciBar strip number

Hit distributions in the spectrometer sections

XPC driftSRPC

SM 1

SM 2

Z position (cm)

Hit distributions in the target section vs Z

emulsions

scintillators

CS

Tracking the (or any short lived particle leading to a second vertex)

In OPERA we use to have the flight length given by the generator

Solution:•Set the lifetime to large values •Track it in the bricks until it has travelled a distance equals to the distance between the 2 vertices

Result:

interaction with

Hits are now recorded in the emulsions

Conclusions

NEGN generator is ready for production

The detector geometry description follows the actual OPERA design (apart from support structures and veto chambers). A summary note is being prepared

Each sub-detector has hits defined to allow digitization

’s leave hits in emulsions

No major upgrade of this version is foreseen since the next generation of software is under construction (OpVMC)

OpRoot is ready to be used for the coming simulation campaign. Need a new version release

Still some work needed in OpDigit package.