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This simulation explores the efficiency and material effects of MCP PET detectors. It analyzes the number of photons detected and generated, as well as the fraction of absorbed photons and photo-electrons. The simulation also considers the impact of different materials and the emission spectra.
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MCP PET Simulation - 6 • # of photon detected at photocathode # 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. Efficiency & Material effect
LSO Black qc Air MCP # of photon detected at photo cathode # 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” Index of Refraction (LSO) = 1.82 Critical Angle( LSO/Air) = 33.3 deg. qc =arcsin( n2/n1) Ratio of solid angle = 19.6% 2(1-cosq) No bulk absorption Mean = 19.5% (%) Ratio of detected photon/absorbed photon Assume no bulk absorption
Bulk absorption length = 20cm Geometry : 1 layer of X-tal + MCPs A) B) C) Mean = 24.4% = 3241 photons Mean = 59.8% = 7945 photons Mean = 15.6% = 2070 photons 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
Emission Spectra(input to geant4) LSO LaBr3 MCP Q.E(Burle Planacon) nm nm nm
2. Efficiency & material effect Case 1) • I = Io * exp( -mx) • = 0.082/mm(absorption coef) => 12.3mm attenuation length 511keV g MCP LSO X-tal thickness(mm) 10,000 events for each set.
Case 2) 511keV g MCP LSO MCP 1 Layer of X-tal + 2 MCPs
4 layers of LSO+2MCPs A+B C # of photo electron/event( after Q.E) • 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)
Plan • Simulation with Pixelated X-tal. Xtal( 4mm x 4mm x 25mm) • Simulation validation