Study of l-aspartic acid for its possible use as a dosimeter in the interval of 3.4–20 kGy at different irradiation temperatures

• The ESR aspartic acid response was studied at different irradiation doses׳ interval and shows a linear response from 3.4 to 20 kGy at 298 K.
• The changes in the ESR signal as a function of the irradiation temperature were investigated.
• Several radicals induced by irradiation produce the ESR signals and two of these radicals are stable at room temperature.

Certain commercial applications of radiation processing increase the efficiency of chemical reactions at low temperatures to decrease the free radicals in the bulk material and avoid the synergistic effects of heat. Such applications have motivated the search for a reliable, low-temperature dosimeter for use under the conditions of the irradiation process. For this purpose, polycrystalline samples of l-aspartic acid (2-aminobutanedioic acid) were irradiated with gamma rays at low temperatures and doses in the kiloGray range (3.4–64 kGy).The potential use of the aspartic acid system as a chemical dosimeter is based on the formation of stable free radicals when the amino acid is exposed to ionizing radiation. These radicals can be studied and quantified using electron spin resonance (ESR). The response curves at different temperatures show that the intensity of the ESR spectra (the five characteristic lines) depends on the dose received. The response of the dosimeter increases with increasing temperature, and this relationship is linear up to 20 kGy at 298 K. The decay characteristics show that the change in the ESR signal over time is low and reproducible. In addition, the l-aspartic acid dosimeter is easy to handle and has low cost.