Rhodamine B and Methylene blue dyed grafted poly(vinyl butyral) films for high-dose radiation dosimetry

Abstract

Gamma radiation-induced polymerization of acrylic acid (AAc) onto poly(vinyl butyral) (PVB) film has been carried out under nitrogen atmosphere. The resulting grafted film of PVB-g-PAAc was allowed to react with solutions of two ionic dyes, namely Rhodamine B (RB) or Methylene Blue (MB). The radiation-induced color bleaching has been analyzed with visible spectrophotometry, either at the maximum of the absorption band peaking at 552 nm (for PVBRB) or that peaking at 651 nm (for PVBMB). The investigations show that these dosimeter films may be useful for high-dose gamma radiation applications. The useful absorbed dose range of the dyed films extends up to 600 kGy for PVBRB and 300 kGy for PVBMB, with a minimum useful dose of about l0 kGy. The type A uncertainty of dose measurements using PVBRB and PVBMB films at two standard deviations (2 σ , approximately equal to 95% confidence limit) was found to be - 8.8 and 9.4%, respectively. The effects of temperature and relative humidity during irradiation as well as pre- and post-irradiation storage, on the radiation response of films are studied. These films are highly stable before and after irradiation and have no appreciable effect of temperature or humidity on response in the relative humidity range 0-60% and temperature range 15-60C.