Spallation effect

Marti, K. and Lugmair, G. W., "81Kr-Kr and K-40Ar ages, cosmic-ray spallation products and neutron effects in lunar samples from Oceanus Procell arum", Proc. Second Lunar Sci. Conf., 1971, 2, 1591-1605. 

Besides natural radionuclides and spallation, a handful of other interesting nuclear interactions lead to observable effects in the noble gases. Some of these are listed in Table 1.6. Most of these involve incidence of a particles or neutrons in nature these are generated primarily by decay of U and Th, the a particles directly, and the neutrons as secondaries by a variety of (a, n) reactions. Again, the list in Table 1.6 is not intended to be exhaustive there are many more reactions that have been found to be significant, in terrestrial samples as well as meteorites, in materials with unusual... 

Thus at a given rate the lowest rubber content which can induce ductility and suppress spallation will result in maximum energy absorption under impact. If this yield-spall transition coincides with the ductile-brittle transition which occurs in these tensile tests, the effective strain rate of the onset of spallation could be predicted by tests of this type. This ductile-brittle transition occurs at low effective strain rates for the unmodified material since it is brittle through the range of conditions used in these tests. For the 4% material at the highest effective strain rates achieved in these tests, the load maximum is just beginning to disappear. Thus, if rate-temperature equivalence holds, extension of these test to... 

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