To compare measurements of relative quantum efficiency made at MIT CSR and XRCF, we have used the data in Table 4.27 to compute relative QE ratios referenced to device S2. The results are presented in Table 4.29 . The telemetry data was taken using windows near the top and bottom of each device to avoid saturating the telemetry stream. This provides additional evidence that spatial variations in efficiency are small in the FI devices and that the absolute efficiencies of these chips are nearly identical at each energy. The agreement between XRCF and CSR is not as good for the BI devices.
Smaller discrepancies are also apparent at several other energies.
The origin of these discrepancies is not understood. Referenced to S2 Device Position Frac.