next up previous contents
Next: UV/Ion Filter and Electrostatic Up: Performance Previous: Field of View

Quantum Efficiency

CsI has been selected as the photocathode material in order to enhance the bare MCP quantum efficiency by about a factor of three in the ROSAT energy range (0.1 to 2.4 keV). The quantum efficiency was measured at a set of discrete energies and at the average angle of incidence for the ROSAT X-ray optics. These data are shown plotted in Figure 4.10 gif and listed in Table 4.4 gif. The features in the plot are based on fitting the measured data points and the major dip around 0.6 keV is due to absorption edges in both Cs and I near this energy.

 fig4-10 figure283


Energy (keV) quantum efficiency
0.3 0.22
0.7 0.18
0.8 0.25
1.5 0.28
1.7 0.23
Table 4.4:   CsI Coated MCP Quantum Efficiency

Michael Arida
Tue Jun 11 16:18:41 EDT 1996