Difference between revisions of "Start Counter Simulations"
From GlueXWiki
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* Properties of optical surface are defined by | * Properties of optical surface are defined by | ||
** Material of surfaces: '''dielectric_dielectric''' | ** Material of surfaces: '''dielectric_dielectric''' | ||
− | ** Physics model: '''unified''' [https://pion.fiu.edu/~puneetk/startcounter/docs/moisan.pdf | + | ** Physics model: '''unified''' [https://pion.fiu.edu/~puneetk/startcounter/docs/moisan.pdf Levin and Moisan, 1996] |
** Transmission efficiency and reflection | ** Transmission efficiency and reflection | ||
** Finish of the surface: '''polished''' or '''ground''' | ** Finish of the surface: '''polished''' or '''ground''' |
Revision as of 12:15, 9 February 2012
Geant4 Simulations
Geometry and Setup
- Scintillator: Imported AutoCAD drawing into GEANT4 using CADMESH utility
- SiPM: 12x12x10 mm volume
- Surrounded by Air
- Spacing between scintillator and SiPM: 0.1 mm
- Generated 10K optical photons at every 2.5 cm spacing inside the scintillator (-300, 300) mm or (0, 60) cm
Material Properties
- Scintillator: ELJAN 212 material composition properties
- Density: 1.023 g/cm3
- Scintillation yield: 10000 photons/MeV
- Optical photon energy range: 0.5 eV - 3.76 eV
- Index of refraction: 1.58
- Absorption length: 400cm (not correct!)
- SiPM: Silicon
- Efficiency: 100%
- Used just to track optical photon hits
Optical Surface
- An optical surface between air and scintillator is set
- Properties of optical surface are defined by
- Material of surfaces: dielectric_dielectric
- Physics model: unified Levin and Moisan, 1996
- Transmission efficiency and reflection
- Finish of the surface: polished or ground
- polished: Fresnel reflection, Total Internal Reflection, Fresnel Refraction
- ground: Spike reflection, lobe reflection, backscatter, Lambertian reflection, Fresnel refraction
Spike reflection: the photon is reflected like a perfect mirror or about the average surface normal Lambertian reflection: the photon is reflected with a Lambertian distribution Back scatter: the photon is reflected in the direction of incidence Lobe reflection: based on the orientation of the micro-facet on the surface. The sigma_alpha parameter defines the standard deviation of the distribution of the micro-facets orientation