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>But an alternative technique,
>>microcalorimetry, is now being used for the most advanced and expensive
>>X-ray detectors.  In essence this measures the heat (ie energy) given
>>to a device at close to 0 K.
>
>I understand that the energy resolution of these microcalorimeter
>detectors is about 1 to 2 eV, about equal to the energy of one light
>photon. So not holding breath is probably wise.
>
>Cheers,
>
>Jim P.

Sure - and that's a huge advance on what other X-ray EDS technology
can offer.  But as far as I can see this is only a technological
limit to resolution, not a theoretical one.  An increase in performance
by an order of magnitude would start to make it useful, and two
orders of magnitude would make it really quite something.

But if I were trying to build a better spectral confocal right now
I'd be more inclined to take a leaf out of your book and use a LN2
cooled linear CCD array spectrometer.  You could bin channels
for fast scanning or integrate for a while and get a really high
quality spectral image.

                                                        Guy

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