spallation

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spallation
1. (nuclear) A nuclear reaction involving the ejection of many particles from an atomic nucleus, following a collision with a high-energy particle. Both the mass number and the atomic number of the target nucleus are changed by the event.

2. (planetary geol.) The removal of the surface layers of a rock by the interaction of a compressional shock wave with the surface, caused by micrometeorite impact. See ‘ZAP PITS’.

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