Status of the OPERA simulation software

1. Status of the OPERA simulation software D.Duchesneau LAPP, Annecy • Introduction: • generator, simulation, digitization status • Recent development in OpRoot • detector geometry implementation • Tracking of the tau • Conclusions OPERA collaboration meeting May 19th, 2003

2. 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 Digitisation Evt generator Simulation NEGN / Jetta OpRoot OpTreeConvert OpDigit digits root ASCII beamfile Hits root Hits root TFolder structure TTree structure Inputs for track reconstruction Physics ... OpDigit nearly ready! Complete chain will be finalized in about 2 weeks Reconstruction

3. Event generator: NEGN OPERA adaptation of the NOMAD event generator (Dario) Includes: Neutrino DIS, QE and Resonant processes Options: Nuclear interactions, ….. • Official release: v1.00 on april 24th 2003 available on LXPLUS, standalone package • Characteristics: • DIS n 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 READY for production. The program produces standard OPERA event beamfiles.

4. 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 geometrydescriptions (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 .

5. OPERA geometrical tree in OpRoot 48 different volumes DTLY

6. All the positioning along the Z axis is based on this drawing Ref: Frascati drawing 12/11/02 -823.4 -452.62 44.88 104.4 etc…… Z (cm)

7. Geometry description in this OPERA implementation From OpRoot • 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

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

9. Emulsion bricks: • 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,

10. Spectrometer part: Uniform B = 1.55 T

11. Spectrometer RPC planes: 21 chambers / plane spacers screws 7.98 m 8.76 m

12. Drift tube planes: 4 layers of 192 tubes 2.03 cm Tube: outer radius 1.85 cm inner radius 1.7 cm length: 8m Wire diameter: 60mm 5.67 cm 4.2 cm

13. Spectrometer XPC planes: 21 chambers / plane spacers To verify: position of the second XPC plane? Before or after the DT plane? 8.06 m 8.75 m

14. ntinteraction with t m Hit visualization: Scintillators Drift tubes emulsions SRPC XRPC 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

15. 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 • fParMassMass 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 • fSciBarstrip number

16. Hit distributions in the spectrometer sections drift XPC SRPC SM 1 SM 2 Z position (cm)

17. Hit distributions in the target section vs Z emulsions scintillators CS

18. Tracking the t (or any short lived particle leading to a second vertex) In OPERA we use to have the t flight length given by the generator • Solution: • Set the t lifetime to large values • Track it in the bricks until it has travelled a distance equals to the distance between the 2 vertices Result: t m Hits are now recorded in the emulsions ntinteraction with t m

19. 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 • t’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.