Ultrasonic absorption in polymer gel dosimeters

Melissa L. Mather, Anthony F. Collings, Nick Bajenov, Andrew K. Whittaker, Clive Baldock

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Ultrasonic absorption in polymer gel dosimeters was investigated. An ultrasonic interferometer was used to study the frequency (f) dependence of the absorption coefficient (α) in a polyacrylamide gel dosimeter (PAG) in the frequency range 5-20 MHz. The frequency dependence of ultrasonic absorption deviated from that of an ideal viscous fluid. The presence of relaxation mechanisms was evidenced by the frequency dependence of α/f2 and the dispersion in ultrasonic velocity. It was concluded that absorption in polymer gel dosimeters is due to a number of relaxation processes which may include polymer-solvent interactions as well as relaxation due to motion of polymer side groups. The dependence of ultrasonic absorption on absorbed dose and formulation was also investigated in polymer gel dosimeters as a function of pH and chemical composition. Changes in dosimeter pH and chemical composition resulted in a variation in ultrasonic dose response curves. The observed dependence on pH was considered to be due to pH induced modifications in the radiation yield while changes in chemical composition resulted in differences in polymerisation kinetics.
Original languageEnglish
Pages (from-to)551-559
Number of pages9
JournalUltrasonics
Volume41
Issue number7
DOIs
Publication statusPublished - 2003
Externally publishedYes

Keywords

  • Polymer gel dosimeter
  • Radiation dosimetry
  • Ultrasonic absorption
  • Ultrasonic attenuation
  • Ultrasonic relaxation

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