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Simulation of NUSTAR crystals with Litrani

Simulation of NUSTAR crystals with Litrani. Presentation of Litrani: simulation of optical photons Preliminary results Light yield Interface with GEANT4 simulations. Meeting at IPNO, Orsay, France. What is Litrani ?. LITRANI stands for LIght TRansmission in ANIsotropic media.

salvador-frederick
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Simulation of NUSTAR crystals with Litrani

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  1. Simulation of NUSTAR crystals with Litrani • Presentation of Litrani: simulation of optical photons • Preliminary results • Light yield • Interface with GEANT4 simulations Meeting at IPNO, Orsay, France

  2. What is Litrani ? LITRANI stands for LIght TRansmission in ANIsotropic media. • General purpose Monte-Carlo program to simulate the propagation of optical photons • ROOT library (Version: 3.3, with ROOT 4.04/02; Windows, Linux with gcc 3.2) • Developped at CEA, Saclay, France for GLAST and the CMS calorimeter (http://gentit.home.cern.ch/gentit/litrani) • Classes and data library from measured materials : • Scintillators: PbWO4, CsI(Tl) • Revetments: Tyvek, VM2000 • Detectors: PMT (XP2020), APD • Surface state: depolished, thin slice of air • Easy to extend the library

  3. Material definition (1) • All properties parametrized as a function of the wavelength • Crystal geometry and parameters: • Light emission • Absorption length • Index of refraction • Revetment: • Diffusion and reflection • absorption • Glue • absorption length • reflectivity • PMT definition • Glass window refraction, absorption length and reflectivity • Photocathode surface and reflectivity • Quantum efficiency

  4. Material definition (2) • Time profile • Wavelength profile

  5. Crystal: CsI(Tl) (Saint Gobain), wrapped with reflector (VM2000, Tyveck?) Geometry: [A]: 22 (h) × 22(w) × 200(l) mm [B]: 22 (h) × 44(w) × 200(l) mm [C]: 22 (h) × 66(w) × 200(l) mm Particles: g (500 keV – 30 MeV) Tests: with (511 and) 662 keV Readout (on face w × h): PMT (Photonis 19 mm Ø, 17 mm PK Ø) APD (square, 10 mm) Goals: Optimize the readout Particle localization Questions Energy resolution Homogeneity Time response Requirements for the simulation Readout (PMT, APD) y g x z w CsI(Tl) h l

  6. PIN – CsI(Tl)#2 y x z Simulation results: yield vs position • Yield over a quarter of the volume (for 50 000 photons emitted), sum over 5 µs • Relative RMS of the yield distribution = contribution of the collection to the resolution / dispersion dominated by the statistics • Optimistic hypotheses on the PIN, dependence on the crystal doping

  7. PMT PIN Simulation analysis with CsI(Tl) #1 • Wavelength: statistics over the whole simulated volume • Result dependent on the wavelength distribution width chosen for the simulation • Histograms can also be available for a voxel

  8. Simulated tracks in a single crystal • Input = ROOT file from GEANT4 simulations by T. Zerguerras • Current algorithm: • Generate a random yield values from the distribution calculated on the volume • Calculate the number of photons received from those yields and the deposited energy • Simulation with the PMT and PIN diode (with CsI(Tl) #1)

  9. Conclusion • The RDD group can carry out a full simulation of the crystal response: resolution and time response • Next steps • Comparison of simulations with measurements (source + different crystals: 22, 44, 66mm) • Refine the models: • APD response • Scintillator response • Consequences of ageing • Detector noise

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