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OK, but why do they need so much X-ray power to examine paintings? Most progress in X-ray technology has been through better sensing so less power could be used

OK, but why do they need so much X-ray power to examine paintings? Most progress in X-ray technology has been through better sensing so less power could be used. Ordinary X-ray tubes are simple and a century old. Now if they could build a compact synchrotron to generate soft X-rays, that would be a huge deal. The semiconductor industry has tried to get that to work for a decade as a light source for "extreme UV". ("Extreme UV" and "soft X-rays" are in the same part of the spectrum.)

SiempreViernes 2y ago
> "Extreme UV" and "soft X-rays" are in the same part of the spectrum. This is true only in the exact same way that the statement "UV and visible light is in the same part of the spectrum", or maybe more clearly "the eyeball and the eyelid are in the same part of the body".
- zmgsabst 2y ago
  I guess it depends on your scale. The X-ray/UV boundary (10nm) is closer to IR (780nm) than the top of X-ray range (10pm). IR is similarly broad (to 1mm).
wycx 2y ago
In this context energy=wavelength=frequency, and hard x-rays means x-ray with energies > approx. 5 keV. I am assuming properties they are after in their particular context are <i>tunable</i> hard x-rays with with relatively narrow bandwidth, such that they can tune the energy/frequency/wavelength of their beam to be above the absorption edge of particular elements in the pigments in paintings and compare the x-ray fluorescence maps above and below the absorption so they can see where particular pigments are and thus paintings hidden below the visible painting. One big advantage synchrotrons have is flux over a broad spectrum. When you want monochromatic x-rays you can start with broad spectrum x-rays from a synchrotron source and throw almost all of the photons away, and still have orders of magnitude more x-rays in your 1 eV bandpass beam than the flux of a laboratory source, (even if it has a peak in its spectrum at the energy you want). The plots on slides 4-6 linked in the first comment [1] demonstrate this clearly. However, the energy range where inverse compton scattering sources seem most attractive are at energies >100 keV where it appears there is the potential for inverse compton sources to approach and even outperform synchrotron bend-magnet sources (slides 31 to 35), particularly in comparison to bend-magnets/wigglers at synchrotrons with lower storage ring energy than facilities like ESRF (6 GeV). High flux at higher energies (>100 keV) is difficult to generate at the more common 2.0-3.0 GeV storage rings. [1] https://indico.cern.ch/event/1088510/contributions/4577523/attachments/2345297/3999135/XLS%20complementary%20use-SmartLight%2020210911.pdf https://indico.cern.ch/event/1088510/contributions/4577523/a...
teilo 2y ago
Because the energy of a photon is a function of its frequency.
azernik 2y ago
It's not a lot of X-ray power - it's more energy per photon. If your photons are tuned to the materials you're looking at, you can get away with less total power.

SiempreViernes 2y ago

> "Extreme UV" and "soft X-rays" are in the same part of the spectrum. This is true only in the exact same way that the statement "UV and visible light is in the same part of the spectrum", or maybe more clearly "the eyeball and the eyelid are in the same part of the body".

zmgsabst 2y ago
I guess it depends on your scale. The X-ray/UV boundary (10nm) is closer to IR (780nm) than the top of X-ray range (10pm). IR is similarly broad (to 1mm).

wycx 2y ago

In this context energy=wavelength=frequency, and hard x-rays means x-ray with energies > approx. 5 keV. I am assuming properties they are after in their particular context are <i>tunable</i> hard x-rays with with relatively narrow bandwidth, such that they can tune the energy/frequency/wavelength of their beam to be above the absorption edge of particular elements in the pigments in paintings and compare the x-ray fluorescence maps above and below the absorption so they can see where particular pigments are and thus paintings hidden below the visible painting. One big advantage synchrotrons have is flux over a broad spectrum. When you want monochromatic x-rays you can start with broad spectrum x-rays from a synchrotron source and throw almost all of the photons away, and still have orders of magnitude more x-rays in your 1 eV bandpass beam than the flux of a laboratory source, (even if it has a peak in its spectrum at the energy you want). The plots on slides 4-6 linked in the first comment [1] demonstrate this clearly. However, the energy range where inverse compton scattering sources seem most attractive are at energies >100 keV where it appears there is the potential for inverse compton sources to approach and even outperform synchrotron bend-magnet sources (slides 31 to 35), particularly in comparison to bend-magnets/wigglers at synchrotrons with lower storage ring energy than facilities like ESRF (6 GeV). High flux at higher energies (>100 keV) is difficult to generate at the more common 2.0-3.0 GeV storage rings. [1] https://indico.cern.ch/event/1088510/contributions/4577523/attachments/2345297/3999135/XLS%20complementary%20use-SmartLight%2020210911.pdf https://indico.cern.ch/event/1088510/contributions/4577523/a...

teilo 2y ago

Because the energy of a photon is a function of its frequency.

azernik 2y ago

It's not a lot of X-ray power - it's more energy per photon. If your photons are tuned to the materials you're looking at, you can get away with less total power.