Journal of Basic & Applied Sciences, 2012, 8, 581-584 581 ISSN: 1814-8085 / E-ISSN: 1927-5129/12 © 2012 Lifescience Global Gamma Radiation Effect on Commercial Reactive Dye in the Range 0-100KGy Using the Idea of the De-Coloration Factor and Extinction Coefficient Taqmeem Hussain 1,* , Muhammad Attique Khan Shahid 1 , Muhammad Shahbaz 2 , Inam-ul-Haq 3 and Hashim Farooq 3 1 Department of Physics, GC University, Faisalabad, Punjab, Pakistan 2 Punjab Institute of Nuclear Medicine (PINUM), Faisalabad, Punjab, Pakistan 3 Department of Physics, University of Agriculture, Faisalabad, Punjab, Pakistan Abstract: In this study the usability of aqueous solutions of SR C4BLN and SGY CRL dyes; as secondary dosimeter was checked using the novel idea of de-coloration factor and extinction coefficient. All samples were irradiated by Co 60 - source in the range 0-10 5 Gy. Absorbance of solutions was noted at max for pre and post irradiation stages. The max of Red and Yellow dyes were 545nm and 448nm respectively. The absorbance%, extinction coefficient and %age of de- coloration factor for each dye were determined. The results showed a gradual decrease in Absorbance% and extinction coefficient while decrease in %age of de-coloration factor with the increase in absorbed dose which confirms the said dyes as secondary dosimeter in stable and safe mode. Keywords: Chemical dosimeters, SR C4BLN, SGY CRL, dosimetry, Absorbance %age, extinction coefficient, de-coloration factor. 1. INTRODUCTION Ionizing radiations can cause chemical and physical changes in the exposed material [1-7]. The search for inexpensive and user friendly dosimeters is an active research area for the physicists and chemists as well. There are numerous dosimeters such as ionization chambers, thermo-luminescent detectors (TLDs), radiographic films, silicon diode dosimeter, alanine dosimeter, plastic scintillators, diamond dosimeter, gel dosimeter, Fricke dosimeter and so forth, and are used for the evaluation of ionizing photons. Dye dosimeters are well documented and different researchers used various colors such as Congo red [8], brilliant green [9], anionic triphenyl-methane dye solutions [10], chlorantine fast green BLL [11] and methyl red [12] to prepare dye dosimeters. However, in this study the suitability of commercial Sandalfix Red C4BLN (SR C4BLN) and Sandalfix Golden Yellow CRL (SGY CRL) dyes were tested to be used as dye dosimeters. It is well known phenomenon that the ionizing radiations cause bleaching of the dye in aqueous solutions. This bleaching of the chosen dye can be used for dosimetry, since the decomposition of the dye linearly depends upon the amount of dose absorbed [3]. To explore the synthetic commercial dye that can be used as a dosimeter is really a challenge. It is known that commercial dyes contain pigmentations (coloring *Address corresponding to this author at the Department of Physics, GC University, Faisalabad, Punjab, Pakistan; E-mail: relyables@yahoo.com substance), which are used to impart color. However, these dyes also have other uses like as chemical dosimeters for high gamma radiation doses [4]. The corresponding chemical changes caused to the irradiated aqueous dye solutions by the gamma radiations can be observed by the respective fading of the dye and hence is the measure of the absorbed dose of the incident -radiations [5]. The dyes used in this study are commercial and cheap dyes, namely, SR C4BLN and SGY CRL, available with the Sandal Dyestuff Industries Pvt. Ltd. Faisalabad. Both of the narrated dyes follow the Beer’s law so the dosimetric calculations were made without any qualm [1, 2]. 2. MATERIALS & METHODS SR C4BLN dye (MW: 1033.5amu) and SGY CRL dye (MW: 1070amu), were used without further purification. 1 gram of each dye was weighted by Electrical Balance Sartorius, Ag Gottingen BL2105 (Germany) and was dissolved in 1 Liter deionized water. The ready solutions had concentration 1gm/L at pH 7.0 measured by pH-meter (Hanna 8417). Owing to high solubility of the dyes in such polar solvents, these were readily dissolved at room temperature 30 o C by a glass stirrer. Different concentrations of the dye solutions were prepared such as C 1 =1 gm/L, C 2 =0.5gm/L and C 3 =0.25gm/L. The prepared samples were preserved at room temperature (30 o C). The dyes have absorption band maxima i.e.,  max =545nm and 448nm respectively, determined by UV-Visible