The effect of high-linear energy transfer ions on the electron paramagnetic resonance signal induced in alanine.

Microcrystalline samples of L-alanine irradiated with energetic high-LET cobalt and iron ions had different EPR spectra compared to alanine samples irradiated with low-LET photons. The differences in the shapes of the EPR spectra and their dependence on the microwave power are related to the differences in the microwave power saturation of the radicals induced by the various types of ionizing radiation. The changes in the shape of the EPR spectra, which were caused by increasing microwave power, were more pronounced in samples irradiated with low-LET radiation than with high-LET particles. This effect showed a long-term stability and can be used to monitor radiation quality.