
X-Rays Expose a Hidden Medieval Library - robin_reala
http://medievalbooks.nl/2015/12/18/x-rays-expose-a-hidden-medieval-library/
======
tonyarkles
So maybe this is naive of me, but it seems like you could scan at 2 or 3
angles and, knowing the physical geometry of the lens system and book,
determine which fragments were on the front and back of the paper. It would
likely be fiddly, but worth an experiment!

~~~
morpher
X-ray lenses don't really exist, although you can produce focused beams (using
either reflection or simply collimation). So, these methods typically involve
scanning a sample and measuring some fluorescence line (which gets emitted in
roughly all directions).

That site doesn't mention the spot size, but its likely much larger than the
page thickness, so the iron signal from a tilted page probably wouldn't differ
in a measurable way from having the page perpendicular to the beam. Keep in
mind that they require ~24 hours to get even the images shown. Instead it
sounds like they rely on compositional differences in the ink from the two
sides and look at fluorescence from an element that is only present on one
side.

It might be possible to get the other side by taking a difference between the
Fe and Ca signals (after scaling appropriately).

~~~
InclinedPlane
Focusing x-rays is not impossible but very difficult. If you look at x-ray
telescopes such as Chandra or XMM-Newton you'll notice they have extremely
long, very high aspect ratio mirrors. This is because x-rays generally only
reflect at grazing angles. At high enough energies you can use particle
physics equipment because gamma rays will produce electron-positron pairs on
impact (allowing you to then track their trajectories and work backwards to
determine the direction of the gamma rays). Such equipment is enormously
expensive and also very large so it's not particularly practical.

------
morpher
Similar x-ray imaging of ancient covered up texts:
[http://www.archimedespalimpsest.org/imaging_experimental4.ht...](http://www.archimedespalimpsest.org/imaging_experimental4.html)

