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HRC-S Off-Axis Quantum Efficiency
XRCF Analysis

v1 - July 1999

The HRC off-axis effective area measurements performed at XRCF were designed to calibrate the spatial response of the quantum efficiency of the microchannel plates. However, since we did not have the same sampling of energies as for the on-axis measurements, we were forced to bootstrap our calculations to the on-axis model. The method by which this analysis was completed is outlined on the HRC-I QE page.

You can view our results as a function of off-axis angle, energy.

I.   QE versus Angle Set

The off-axis quantum efficiency of the HRC-S was measured at 20 angles at XRCF. This clickable map below of spot locations will take you to tables containing the absolute QE results for that angle-set of measurements.

II.   QE versus Energy Set

The off-axis quantum efficiency of the HRC-S was calibrated at 11 energies at XRCF. We have investigated (by Energy) the absolute QE, the QE relative to the on-axis QE, and a spatial comparison with a normalized PRE-fix flat field. All studies are made versus Angle and Radial Distance. We define the relative quantum efficiency as (QE(r=0)/(QE(r)), where QE(r) is the absolute quantum efficiency at radial distance r from the optical axis.

For the spatial study of the off-axis QE, we have compared the XRCF data to a normalized PRE-fix flat field made in the HRC Lab. This can provide a quantitative verification of QE versus Energy at the specific XRCF spot locations. The spatial comparisons, then, are simply the QE(flat field) - QE(xrcf) Residuals versus Radial Distance. However, the comparison is misleading for a current understanding of the HRC-S. As a result of the poor performance at XRCF, the electronics settings for the HRC-S have since been modified toward an improved gain and flatness of the detector. (See the HRC Ground Calibration Final Report Rev. A on the HRC HomePage for details.) So even though we normalize to the on-axis QE from XRCF data, we know that the post-XRCF general flat field shape has changed. Thus, this study does not represent the current state of the detector. The PRE-fix flat field used for this analysis was provided by Charlie Wilton. Click for a surface plot image as well as a FITS image (shift-click to download). A similar study of the HRC-I, with further explanation, can be found on the HRC-I Spatial QE page.

The Table below compiles by energy the data files containing the studies of the absolute QE, the QE relative to the on-axis QE, and a spatial comparison with a normalized PRE-fix flat field, versus Angle and Radial Distance. Click for details.

Energy Absolute QE/Relative QE/SAC Flat Field QE
vs. Radial Position
  Data                                                 Plots
0.183 v1                                                 v1
0.277 v1                                                 v1
0.392 v1                                                 v1
0.784 v1                                                 v1
0.905 v1                                                 v1
1.176 v1                                                 v1
1.487 v1                                                 v1
1.810 v1                                                 v1
3.500 v1                                                 v1
4.960 v1                                                 v1
7.000 v1                                                 v1

Questions, Suggestions, Reflections: cxccal@cfa.harvard.edu