R3B simulations status

Transcription

1 R3B simulations status Héctor Alvarez Pol GENP, Univ. Santiago de Compostela developers H. Alvarez Pol (USC), S. Beceiro (USC), M. Cherciu (ISS Bucharest), B. Fernández (Univ. Liverpool), O. Kiselev (GSI), M. Labiche (Univ. Paisley), S. Paschalis (Univ. Liverpool), M. Potlog (ISS Bucharest), C. Rodríguez Tajes (USC)

2 INDEX 1. status 2. LAND simulations 3. TPC simulations

3 : overview is a simulation code for the R3B setup, also useful for present Cave C experiments By now, a pure GEANT 4 + ROOT program Features a multihit data structure ready for event loop analysis A modular geometry description allows the integration of new detectors features: A large set of materials is included both for the crystal and the environment; for the crystals: LaBr3, CsI, NaI, PWO, BGO...; for the environment: air, vacuum... Messenger commands for user control (online) Data structure and persistency classes modularized ROOT libraries included for a fully integrated analysis interface Partially documented (code is written in OO/C++ style, that is, readable ; ) provides a new data structure All detectors in a single TTree with individual branches per detector Branches made of TClonesArray (collections) of detector Hits Full access to the filling of the Hit information Examples, README, HOWTO files available

4 Physics lists and event generators Physics lists: a whole world of particles and interactions (enjoy it!) G4 allows and enforces a full customization of the physics description Available Physics lists Electromagnetics: standard, low energy, penelope Hadronic: some basic processes could be directly started from the macro; any physics list can be compiled within the code => Event generators Present version of lacks of real physical event generators Ongoing work: quasielastic, knock out (p,2p), charge exchange... are under development (Milano, Madrid, UK, GSI,...) Discussions ongoing about a common interface for nuclear physics Problems with known physics event interfaces due to particle ID scheme So, what is in? Gamma source for testing calorimeter (Lorentz boost, realistic target interaction,... included) Proton basics elastic scattering and transfer reactions for testing Whatever particle (or set of) that the user wants to throw in

5 Detectors in : Silicon tracker Silicon tracker Octogonal geometry for R3B Geometry for test experiments under development (BF, ML) Geometrical description and digitization scheme under discussion

6 Detectors in : CALIFA geometry Available geometries in : v1.2 initial design as described in R3B_CAL_01/05 v4.0b presented by J.Peyre at Orsay Cal WG meeting v4.0b with corrected lengths for the crystals Crystal length selection (v4.0b): Three calorimeters with different crystal size combinations have been simulated (SHORT, MEDIUM, LONG) For each calorimeter, lengths are selected to cover approx. the same photopeak 5MeV CoM Overlap problems, corrected in simulation (temporal solution) Three different models: Short, Medium and Large Short Medium Long Energy 700 AmeV Chosen for approx. 60%, 70% and 80% 5MeV CoM Angle (deg) E_lab/E_CM E_lab for 5 MeV CM Approx. Multiplicative factor Crystal length (cm)

7 Detectors in : Darmstadt Heidelberg Crystal Ball Darmstadt Heidelberg Crystal Ball Based on GEANT3 geometry description Some problems detected on G3 geometry corrected (scaling) A better description could be implemented in next future (SB) Report on the translation G3 to G4 in /u/land/geant4/r3b/techreport.pdf

8 Detectors: Drift chambers Drift chambers A simple gas volume Aluminum frames and mylar windows are now in A simple digitization scheme already working A more elaborate scheme under development Realistic output (based on the existing cell/layer structure)

9 Detectors: GFI and TOF walls GFI A simple scintillator volume with frames A simple digitization scheme already working Some work to do... TOF walls MiniTOF (ions) and protons TOF wall under implementation

10 Other setup elements: magnets, targets... Magnets ALADIN implemented R3B magnet implemented (geometry not included, only field map) Both cases based on interpolation of the field map with different grids Primary information Stored in the TTree for later access during the analysis Full information about all primaries (vertex particles) Targets Parafin targets (0o and 45o) LiH target Easy implementation of new geometries

11 R3B LAND simulations Reported by M. Potlog: Tests trying to understand neutron interaction in Geant4 Comparison with Saturne experiments (scintillator paddles on neutron beam) Bertini QGSP_BERT_HP and Binary QGSP_BIC seems to have the proper high energy neutron interactions Still a large difference with the exp. data Individual physics processes under test FLUKA (M. Cherciu): Implementation of the Saturne test geometry Comparison made for 200MeV neutrons Ongoing work for 500MeV and 1GeV

12 R3B LAND simulations

13 R3B TPC simulations Reported by K. Kezzar Already done tasks: Study the geometry of the detector Tracks reconstruction of fragments (using spallation events as input) Signal reconstruction in the detection planes Present work (in parallel with testing prototypes): Study the possibility of multiplexing in order to reduce the number of channels A more complete report will be ready beginning of March

14 Conclusions is a working simulation program for R3B and cave C experiments: describes part of the present detectors simple analysis macros available for calorimeter only, easily expanded under test; developers and betatesters needed More info: LAND detector sim: Physics Lists studies using Saturne tests; geometry TPC detector sim: geometry and track reconstruction ready Ongoing or future developments: complete Cave C setup improve description on relevant detectors; detector integration event generator should be soon incorporated; waiting for physics......

15 Example: Calorimeter analysis Lorentz boost effects Simulation for FRS S245 O 700 AMeV 1 n removal (22O decay scheme) 23 The very low efficiency at high energy makes very difficult to reconstruct the 3.2 MeV peak Perfect Doppler correction

16 Example: R3B Calorimeter vs. MINIBALL G4double distribution = RandFlat::shoot(0.,183.); if(distribution < 100.) GammaEnergy = 3199.; else if(distribution < 146.) GammaEnergy = 1383.; else if(distribution < 147.6) GammaEnergy = 1710.; else if(distribution < 166.6) GammaEnergy = 2601.; else GammaEnergy = (RandFlat::shoot(0.,5000.))*keV; if(distribution < 166.6) //transform into lab frame else //no Lorentz boost //100% //46% //1.6% //19% //~10% MINIBALL CALIFA Other cases requested for simulation: decays at lower energies dipole resonances...

17 Example: Cave C next year experimental setup

18 How to GSI A fast guide to at GSI (linux cluster, Debian 3.1) v0.3 available (CB in, but not yet DCH, ALADIN...) New stable versions will be available as soon as produced Ugh, I cannot wait for a stable version! So, download it from subversion repository for developers/testers (ask me for passwd) How to: Log as land Run configuration script Move to /u/land/geant4/r3b/ You are ready for running More details in report: /u/land/geant4/r3b/techreport.pdf Some macros for: Testing the CB Testing the full set of detectors Testing the R3B calorimeter Soon also for ALADIN setup

19

20