1. 1 MCP PET Simulation - 6 1.# of photon detected at photocathode 2. Efficiency & Material effect # of generated photon at 511keV 26000/MeV * 0.511 = 13286. # of photon at peak = ~13240 # of photo-electron( after Q.E applied) # at peak = ~370.

2. 2 # of photon detected at photo cathode MCP Air LSO Black cc Index of Refraction (LSO) = 1.82 Critical Angle( LSO/Air) = 33.3 deg.  c =arcsin( n2/n1) Ratio of solid angle = 19.6% 2(1-cos  ) # of photon generated = absorbed photons at the side walls+ bulk absorbed photons + detected photon at photo cathode Bulk absorption length = ~ 20cm. “Average distance traveled by a phton before being absorbed by the medium” Ratio of detected photon/absorbed photon Assume no bulk absorption (%) No bulk absorption Mean = 19.5%

3. 3 Bulk absorption length = 20cm Geometry : 1 layer of X-tal + MCPs A) Fraction of detected photons(%) ( => 2070 * 0.2(QE) = 414 p.e) B) Fraction of bulk absorbed photons C) Fraction of absorbed photons at side walls A)B)C) Mean = 15.6% = 2070 photons Mean = 24.4% = 3241 photons Mean = 59.8% = 7945 photons

4. 4 Emission Spectra(input to geant4) LSOLaBr3 Light Yield26,000/MeV60,000/MeV Decay time40ns20ns Refractive index1.881.82 Attenu. length1.2cm2.1cm Photo-fraction32.5%15% Peak wavelength420nm370nm nm LSOLaBr3 MCP Q.E(Burle Planacon)

5. 5 2. Efficiency & material effect Case 1) LSO MCP 511keV  LSO thicknessno interaction Interaction at MCP Interaction at Xtal 10mm34.5(%)6.0(%)59.5(%) 20mm15.6(%)2.7(%)81.8(%) 30mm6.6(%)1.2(%)92.3(%) 40mm3.0(%)0.6(%)96.4(%) 10,000 events for each set. I = I o * exp( -  x)  = 0.082/mm (absorption coef) => 12.3mm attenuation length X-tal thickness(mm)

6. 6 1 Layer of X-tal + 2 MCPs Case 2) LSO MCP 511keV  MCP LSO thicknessno interaction Interaction at MCP Interaction at Xtal 10mm27.8(%)14.6(%)57.6(%) 20mm12.0(%)9.3(%)78.8(%) 30mm5.1(%)8.5(%)86.4(%) 40mm2.6(%)6.9(%)90.5(%)

7. 7 4 layers of LSO+2MCPs Generated 10000 events. Fraction of no interaction event : 0.6% ( set A) Fraction of MCP interaction event : 10.9% (set B) Fraction of X-tal interaction event : 88.5% (set C) A+B C # of photo electron/event( after Q.E)

8. 8 Plan Simulation with Pixelated X-tal. Xtal( 4mm x 4mm x 25mm) Simulation validation