MCP-PET: Geant4 Simulation Geometry Implementations 1. Similar to the last report (polished surface). Scintillator : LSO, LaBr3 # of layers : 5 -> 4 Area : 51x51mm -> 102x102mm 2. Wavelength shift plastics/optical fiber Collect light on the side wall of X-tal. Need input parameters for WLS plastics. e.g) refractive index, absorption length, emission spectrum,.. Surface condition( Ground -> Polished) for total internal reflection.

4-Layer Micro-Pet Sampling Calorimeter Wave-Form Sampling Electronics

Emission Spectra(input to geant4) LSOLaBr3 Light Yield26,000/MeV60,000/MeV Decay time40ns20ns Refractive index Attenu. length1.2cm2.1cm Photo-fraction32.5%15% Peak wavelength420nm370nm nm LSOLaBr3 MCP Q.E(Burle Planacon)

Emission Spectra(geant4 output) nm LSO LaBr3 Emission spectra of LSO, LaBr3 Before/After MCP Q.E applied

# of photoelectron at photo-cathode # of p.e at 1 st lalyer Sum of 2 sides( front and back) 371 for LSO 976 for LaBr3( ~2.6 times larger than LSO) LaBr3 has more compton scattering events. # of p.e ( LSO) LaBr3

Hit layer(1,2,3,4) layer LSO LaBr3 Shows that LSO has higher stopping power than LaBr3.

Detection Efficiency LSOLaBr3 Layer Layer Layer Layer Sum87.4(%)78.9(%) Requiring # of photo-electron > 50. Mutiple layers can have hits in an events. ( by compton scattering) # of photo-electron(LSO): sum of 4 layers LaBr3 ?

Light spread( at photo-cathode) X of p.e ( Single event) RMS of the X spread mm X of p.e ( all the first layer hits) Light spread : RMS ~ 4.5mm Consistent with simple calculation: crystal length : 10mm rindex : 1.82(LSO) -> 1.00 critical anlge : 33.3 deg 10mm*tan(33.3) = 6.5mm

Plans Investigate material effects 4mm of T-Line width. Extract Energy, Timing resolution Implement WLS bar/ fiber