A new preprint perhaps related to this topic --
Observation of x-ray emission and matter collapse in lead
https://arxiv.org/abs/1804.00530
ABSTRACT:
The action of focused underwater shock waves on a lead sample is revealed to
be not restricted by a mechanical influence only. A strong unexpected x-ray
emission was registered from the lead foil exposed to shock waves which are
extremely adiabatic compared to processes of x-ray generation. The lead foil,
acted by shocks, misses a part of its area in the form of a polygon hole of the
size of ∼2mm. The missing polygon of the lead foil looks as a delicately
removed part with no damage of hole surroundings (as it should be at a strong
mechanical breaking) which remains flat as before the shocks action. That
missing polygonal lead matter seems "disappeared" because it, or its parts,
were not found in the plastic container. Also there are no lead traces on
plastic surfaces contacting the lead during exposure to shock waves. The
theoretical backgrounds of those paradoxical phenomena in terms of anomalous
electron states are presented.
Several other related papers by one of the authors are URL: