| About ROSAT |
ROSAT Home Page | ROSAT Images |
|---|
In order for the PSPC to record an incoming X-ray photon as an event, the
photon must first be transmitted through the PSPC entrance window, and,
second be absorbed in the counter volume. The PSPC entrance window
is a 1 
m foil of polypropylene coated with 50 g cm 
carbon
and 40 g cm lexan. As a consequence, the window is basically
opaque at energies just above the carbon edge at 0.28 keV, but transmitting
at about 50 percent just below the carbon edge. The X-ray absorption of the
counter gas is close to 100 percent almost up to 2 keV where
the X-ray mirror cuts off. The resulting quantum efficiency as a function
of energy is shown in Figure 4.5 
.
