Unfortunately, 10^-13 m is about two orders of magnitude smaller than the spacing of atoms in a crystal. So, you have the problem of finding a periodic structure which has a periodicity of the order of the wavelength.

At first glance you would need to pack charged particles much closer than the average distance between an electron and the nucleus in an atom (well, there is a reason why gamma radiation is linked to nuclear reactions).

Also, the interference pattern from a periodic structure depends on the direction (just think about the double slit experiment).

Assuming you can find a solution to the spacing problem, I do not see how you can make a shield with interference alone.
Probably you could think of some setup where interference is used to enhance the probability for gamma photons to be absorbed (for example, increasing the path length within an absorbing material).

[...]

On second thought, I seem to have a faint memory of something that works like a mirror but uses interference. Unfortunately you would still have the wavelength problem.

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papageno


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