406 Journal of Basic & Applied Sciences, 2016, 12, 406-410 ISSN: 1814-8085 / E-ISSN: 1927-5129/16 © 2016 Lifescience Global Preliminary Studies for Dosimetric Response of a Synthetic Dye for Gamma Dosimetry Muhammad Khawar Hayat 1 , Ramiza 1 , Taqmeem Hussain 2,* , Abdul Hanan Saeed 1 , Inam ul Haq 1,4 and Nasim Akhtar 3 1 Department of Physics, University of Agriculture Faisalabad (UAF), 38040-Faisalabad, Pakistan 2 Department of Physics, Government College University Faisalabad (GCUF), 38000-Faisalabad, Pakistan 3 Nuclear Institute of Agriculture and Biology (NIAB), Faisalabad, Pakistan 4 Higher Education Department, Government of Punjab, Pakistan Abstract: Aqueous solutions of Sandalfix Orange C2RL (SO) dye were used to check its feasibility as a new passive dosimeter. UV/VIS spectrophotometer was utilized to determine the absorption peak (λmax) of dye; which was 430 nm. SO followed Beer’s law satisfactorily. The absorbance (A) of the sample solutions was decreased with increase in absorbed dose (D). The %decoloration (%Ð) showed an exponential increase and logarithmic increase within low and high dosimetry range, respectively. The pH sensitivity of the sample solutions at different doses was also observed. Keywords: Aqueous Solutions, Reactive Orange 122, Gamma radiation, %Decoloration, Absorbance. INTRODUCTION Biological, chemical and physical changes occur in material(s) exposed to radiations [1-2]. The process of calculating the quantity of absorbed Ionizing Radiations (IRs) is called Radiation Dosimetry. Some of the dosimeters are based on chemicals that respond linearly, logarithmically or exponentially etc. to IRs under suitable conditions. Chemical change upon irradiation is the general working principal of a chemical dosimeter. Irradiation can change the thermo- luminescence and other optical properties of alkaline earth and rare-earths metal compounds; which were conveniently used as a dosimeter. Dye, a synthetic chemical; is used to impart color and has been used for dosimetric purposes in many of its forms like aqueous solutions [3-9] and polyvinyl alcoholic films [10-12] etc. In the aqueous solution, irradiation can cause the production of transient species i.e., ions and radicals etc. Radiolysis produces hydrated electron, H 2 O 2 , H 2 , OH - , H + and •OH radical as intermediate species; the production depends upon the linear energy transfer value of radiation [13]. Dyes are categorized on the bases of their source, color, structure and method of application in color index. Chromophoric groups are the major cause for the division of the dyes; and dyes can be characterized as azo dyes, arylmethane dyes, acridine dyes, nitro dyes, anthroqinone dyes, quinine-amine dyes and xanthene dyes [14]. *Address correspondence to this author at the Department of Physics, Government College University Faisalabad (GCUF), 38000-Faisalabad, Pakistan; E-mail: relyables@yahoo.com Different dyes have been used by researchers i.e., bromophenol blue [15], methyl red [16], sandalfix golden yellow CRL and sandalfix red C4BLN [4-7], direct yellow 12 [13], methylene blue [10], alizarin yellow GG [17], reactive yellow 145 [18] and 2, 6 dinitro phenol [19] etc. Radiolysis causes degradation of the dye; and is a well-known radiation induced phenomenon. Degradation of the dye is initiated absolutely by •OH attacking on the electron-rich sites of the dye molecules and can be used for dosimetric studies. The proposed plan of present study is to find the dosimetric response of aqueous solutions of the synthetic dye; when exposed to different gamma dose ranges. MATERIALS AND METHODS Sample Preparation and Pre-Irradiation Treatments Sandalfix Orange C2RL (SO) (MW: 1034.27 amu, Molecular Formula: C 31 H 20 ClN 7 Na 4 O 16 S 5 ) was collected from Sandal Dyestuff Industries Pvt. Ltd. Faisalabad, Pakistan and was used without further purification. The sample solutions were prepared by dissolving 0.5 gram (weighted by Mettler H35AR (USA) balance) of the selected dye in one liter of deionized water, collected from Pakistan scientific traders, Faisalabad, Pakistan, and it has electrical conductivity less than 1 µSiemens/cm. The pH of sample solutions was measured by pH meter (Hanna HI 83141) and controlled by using one molar solution of NaOH and HCl, respectively. The set of acidic samples have pH