Comparison Between MIT and XRCF (Phase I) Measurements of Relative Quantum Efficiency

 

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. Similarly, we have compiled relative QE ratios referenced to S2 from telemetry data taken at XRCF (see Table 4.30). The telemetry data was taken using windows near the top and bottom of each device to avoid saturating the telemetry stream. In Table 4.31 we have computed the fractional difference (CSR-XRCF/CSR) between the relative QE measurements made at each site. The relative QE ratios at XRCF for the FI devices are in excellent agreement with the ratios obtained at CSR. 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. At 0.525 keV, both S1 and S3 appear to have been 10-15% more efficient relative to S2 in the XRCF data compared to the CSR data. Smaller discrepancies are also apparent at several other energies. The origin of these discrepancies is not understood. Examinations of the effects of windowing at XRCF and differences in the source spectra at CSR and XRCF have not resolved this issue.

 

Device Position Mean (RMS) Relative Efficiency vs. Energy (keV)

0.525 0.677 1.740 2.015 4.509 5.894 8.040

O F Si P Ti Fe55 Cu

w203c4r I0 0.860 0.791 0.993 0.920 0.990 0.970 0.936

(0.031) (0.031) (0.043) (0.040) (0.043) (0.044) (0.044)

w193c2 I1 0.877 0.796 0.976 0.950 0.990 0.967 0.898

(0.037) (0.036) (0.052) (0.052) (0.050) (0.053) (0.054)

w158c4r I2 0.906 0.834 0.987 0.964 0.991 0.965 0.905

(0.038) (0.038) (0.052) (0.051) (0.050) (0.052) (0.051)

w215c2r I3 0.883 0.808 0.993 0.924 0.976 0.977 0.932

(0.032) (0.031) (0.040) (0.038) (0.038) (0.040) (0.041)

w168c4r S0 0.935 0.867 1.001 0.947 0.993 0.965 0.919

(0.037) (0.035) (0.042) (0.039) (0.041) (0.041) (0.042)

w182c4r S2 1.000 1.000 1.000 1.000 1.000 1.000 1.000

(0.000) (0.000) (0.000) (0.000) (0.000) (0.000) (0.000)

w457c4 S4 0.903 0.858 1.002 0.951 0.995 0.991 1.003

(0.032) (0.036) (0.045) (0.043) (0.043) (0.045) (0.048)

w201c3r S5 0.889 0.823 0.996 0.926 0.995 0.992 1.008

(0.032) (0.032) (0.042) (0.039) (0.041) (0.043) (0.047)

w140c4r S1 2.985 2.589 1.030 1.431 0.930 0.718 0.524

(0.155) (0.139) (0.065) (0.104) (0.092) (0.066) (0.047)

w134c4r S3 2.950 2.399 1.068 1.461 1.003 0.833 0.640

(0.139) (0.168) (0.060) (0.085) (0.064) (0.058) (0.052)

 

 

Device Position Mean Relative Efficiency vs. Energy (keV)

0.277 0.525 0.705 1.487 1.740 2.166 4.509 6.399 8.040

C O Fe L Al Si Nb L Ti Fe K Cu

w203c4r I0 0.839 0.808 0.962 0.980 0.950 0.981 0.948 0.903

w193c2 I1 0.873 0.803 0.965 0.978 0.962 0.985 0.946 0.910

w158c4r I2 0.915 0.847 0.979 0.995 0.977 0.988 0.951 0.894

w215c2r I3 0.876 0.806 0.976 0.992 0.969 0.989 0.907

w168c4r S0 0.687 0.908 0.873 0.979 0.986 0.964 1.002 0.953 0.904

w182c4r S2 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000

w457c4 S4 0.625 0.902 0.910 0.975 0.991 0.965 1.005 0.980 1.049

w201c3r S5 0.625 0.880 0.828 0.966 0.983 0.966 0.999 0.972 1.008

w140c4r S1 36.619 3.460 3.022 1.071 1.034 1.287 0.847 0.617 0.527

w134c4r S3 35.679 3.280 3.033 1.115 1.093 1.343 0.949 0.756 0.672

 

 

Device Position Frac. Rel. Eff. Diff. vs. Energy (keV)

0.525 1.740 4.509 8.040

O Si Ti Cu

w203c4r I0 +0.021 +0.013 +0.009 +0.035

w193c2 I1 +0.010 -0.002 +0.005 -0.013

w158c4r I2 -0.003 -0.008 +0.003 +0.012

w215c2r I3 +0.020 +0.001 -0.013 +0.027

w168c4r S0 +0.024 +0.015 -0.009 +0.016

w182c4r S2 0.000 0.000 0.000 0.000

w457c4 S4 +0.007 +0.011 -0.010 -0.046

w201c3r S5 +0.015 +0.013 -0.004 0.000

FI Mean +0.013 +0.006 -0.003 +0.004

FI Std Dev. 0.010 0.009 0.009 0.027

w140c4r S1 -0.159 -0.004 +0.089 -0.006

w134c4r S3 -0.112 -0.023 +0.054 -0.050