Gain by Photon Transfer method

[Gerard Luppino]

Hi Roger and all,

You are absolutely right abou the window. To use Fe55
x-rays you need to swap the optical window for an x-ray
transmitting window (Be, say) or mount the source inside
the dewar. Either way, its a pain for a camera in regular
use in an observatory setting. However, Jim Janesick showed
us an alternative a few years back. Instead of using a
5.89 keV Fe55 source, you can use a ~22keV Cd source.
A lot of these x-rays will get through most dewar windows.
They'll also zip right through the CCD, but I understand that
enough will have interactions that you can use the same technique.
This time, of course, you'll generate ahcrge packets of
22 keV/3.65 eV/e-h pair.  I've been wanting to get such a source
for years, but have never gotten around to it. Indeed, the
photon transfer curve method is straightforward enough that
it can be used fairly reliably for getting the "gain".

Aloha,

Gerry