Dye-precursors made from furfural and some aniline derivatives become red-colored upon irradiation with ionization radiations in PVC matrix, forming Stenhouse salts with the HCl evolved from the matrix. The coloration of the precursor from N-methylaniline, having the most excellent potential for dosimetry among the precursors, was studied for the irradiation of electron beam (60 kV) and X-ray (50-240 kVp).
The following conclusions were obtained for the electron beam bombardment.(1) The response range is 10
-8-10
-6 C/cm
2 or 10
3-10
5 rad, where good linearity between coloration and charge density exists.(2) The highest sensitivity is obtained when the concentration of the precnrsor is≥5 wt% for the amount of PVC and the film thickness is≥32μm.(3) Addition of 25 wt%of DOP enhances not only the sensitivity by ca. 20% but also the stability of the color from several days to several months.(4) The sensitivity is increased by ca. 15% when a conductive base is used for the film.(5) G value for the formation of the dye, i.e., that for the formation of HCl is 13.5-15.5.
The followings were obtained for the irradiation of X-ray.(1) The response range is 10
3-10
5 R or rad.(2) The sensitivity for the absorbed dose is independent of the energy but is approximately proportional to the film thickness.(3) The sensitivity is higher than that for electrons by the factor of ca. 1.6, reflecting the higher G (HCl) value, 23-25.
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