Pair spectrometer overview
GEANT Simulation (old)
Pair Spectrometer's geometry implemented in the GEANT simulation.
The top plot corresponds to the elevation and the bottom plot corresponds to the plan views.
Energy resolution of 24 FSF (top) and 6 WSF (bottom) counters estimated with the GEANT simulation. The converter thickness corresponds to . The contribution from the beam spot size (~ 4 mm at the converter) to the energy resolution dominates for the high-energy bins of the WSF counters.
Photon energy spectrum measured by the pair spectrometer. The plot is obtained by requiring a coincidence between the FSF and WSF counters and contains 24 x 6 = 144 energy bins. The coincident rate corresponds to a high-luminosity run ( photons/sec in the coherent peak ) using Aluminum converter with the thickness of radiation lengths.