Detailed Simulation of Crystals short update Weekly dual

Detailed Simulation of Crystals short update Weekly dual read out meeting Hans Wenzel Fermilab 23 rd February 2010

Outline • Goal: make simulation as realistic as possible. Swiss army knife of Crystal simulation. – New Version of Geant 4 (4. 9. 3). – New LUT available for BGO reflectivity (based on LBL measurements). (besides glisur and unified) – Different geometry. – Add and optimize optical (for CPU speed) properties. – Allow to set Birks constant. – Allow the change of physics list, enable disable optical processes – All parameters can be changed via the command line. – Code is in CVS (Eshinn) → will move http: //cdcvs. fnal. gov/cgi-bin/public-cvs/cvswebpublic. cgi/EShinn/Crystal. Sim/? cvsroot=ilcdet January 22 2009 Hans Wenzel 2

Crystal Geometry Crystal: 2 x 2 x 20 cm Light absorbing Wrapper Ideal Photodetectors January 22 2009 Hans Wenzel Also the volume itself Is a sensitive volume. Give result: with/without Birk suppression em/had and other classification Not yet implemented yet: slic like sensitive detector where the optical photons are produced but not tracked 3

Setting optical properties and Birks Constant in Geant 4 (used by scintillation process) G 4 Material. Properties. Table* my. MPT 1 = new G 4 Material. Properties. Table(); my. MPT 1 ->Add. Property("RINDEX", Photon. Energy, Refractive. Index 1, n. Entries); my. MPT 1 ->Add. Property("ABSLENGTH", Photon. Energy, Absorption 1, n. Entries); my. MPT 1 ->Add. Property("SLOWCOMPONENT", Photon. Energy, Scintil. Slow, n. Entries); my. MPT 1 ->Add. Const. Property("SCINTILLATIONYIELD", 8500. / Me. V); my. MPT 1 ->Add. Const. Property("RESOLUTIONSCALE", 1. 0); my. MPT 1 ->Add. Const. Property("SLOWTIMECONSTANT", 300. * ns); my. MPT 1 ->Add. Const. Property("YIELDRATIO", 1); BGO->Set. Material. Properties. Table(my. MPT 1); // Set the Birks Constant for the BGO scintillator BGO->Get. Ionisation()->Set. Birks. Constant(0. 126 * mm / Me. V); January 22 2009 Hans Wenzel 4

BGO optical properties (I) January 22 2009 Hans Wenzel 5

BGO optical properties (II) 2. 5 cm BGO January 22 2009 Hans Wenzel 6

Geant 4: produced Scintillation light 2 Ge. V Muons (2 cm BGO): 171500 Scintillation photons/evt. Decay time 300 nsec January 22 2009 Hans Wenzel 7

Geant 4: produced Cerenkov light 2 Ge. V Muons (2 cm BGO): 1430 Cerenkov photons/evt January 22 2009 Hans Wenzel 8

Geant 4: light at the photo detectors 2 Ge. V Muons (2 cm BGO): -----------------10500: Szintillation ph/sensor 90: Cerenkov ph/sensor ~ 12% January 22 2009 Hans Wenzel 9

LUT (Reflectivity) Derived from measurements At LBL: M. Janecek, W. Moses IEEE Transactions on Nuclear Science Now part of regulare geant 4 distribution as of 4. 9. 3 • • polishedlumirrorair, // mechanically polished surface, with lumirror polishedlumirrorglue, // mechanically polished surface, with lumirror & meltmount polishedair, // mechanically polished surface polishedteflonair, // mechanically polished surface, with teflon polishedtioair, // mechanically polished surface, with tio paint polishedtyvekair, // mechanically polished surface, with tyvek polishedvm 2000 air, // mechanically polished January 22 2009 Hans Wenzel 10

How to use the LUT set an environment variable, G 4 REALSURFACEDATA, to the directory of geant 4/data/Real. Surface 1. 0. // ------- Surfaces -------// // Quartz Bar/Air // G 4 Optical. Surface* Op. BGOSurface = new G 4 Optical. Surface("BGOSurface"); Op. BGOSurface->Set. Type(dielectric_LUT); Op. BGOSurface->Set. Model(LUT); Op. BGOSurface->Set. Finish(polishedtyvekair); G 4 Logical. Border. Surface* BGOSurface = new G 4 Logical. Border. Surface("BGOSurface", BGOBar_phys, exp. Hall_phys, Op. BGOSurface); January 22 2009 Hans Wenzel 11

Some results 2 Ge. V Muons (2 cm BGO): 100 Events Name of Surface Szintilator. Hits on PD Cerenkov. Hits on PD Dielectric metallic 2430548 23441 etchedteflonair 1814200 16102 groundteflonair 350466 2108 groundvm 2000 air 335703 2097 groundvm 2000 glue 965374 7107 polishedtyvek 2484005 24191 etchedtyvekair 2090949 18220 January 22 2009 Hans Wenzel 12