The aim of this paper is to find the effect of type of etchant solutions on nuclear track detector CR-39 . CR-39 detectors were irradiated with alpha particle from 241 Am. The irradiated detectors were etched in a number of some newly introduced etching solutions as well as in conventionally used 7 N NaOH and 7 N KOH at 70 °C. The newly prepared etching solutions included NaOH/1-propanol. Processing conditions were optimized for these etchants. From alpha track diameters, bulk etching velocity

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... B , track etching velocity V T , etching efficiency η , etching ratio V , sensitivity S and critical Angle θ C and their activation energies were determined and compared with that obtained for 7 N NaOH and 7 N KOH at 70 °C The activation energy of CR-39 polymer detector (bulk or track) is defined as the energy required to activate the reaction between the detector material and the etchant solution [11]. Many works [12,13] studied the activation energy of the CR-39 polymer detector.. It tells us about the kinetics of the reaction. Figure 5 a, b show ln VT as a function of T-1 (10 4 K−1 and ln VB as a function of T-1 (10 4 K−1 ) for NaOH ,KOH and NaOH/1-propanol . At any particular temperature it can be seen that VB and VT are higher for NaOH/1-propanol etchant, than that for KOH, etchant and this one is higher than that for NaOH etchant . The values of activation energies were obtained from slopes of straight lines, shown in Figure 5 a,b they are tabulated in table 4. The values of EB and ET agree with results of [14 ] . Higher value of activation energy indicates a greater temperature dependence of the reaction rate [10]. This was clearly observed in our data obtained for all etchants. It was also observed that the track activation energy ET is lower than the bulk activation energy EB. It reveals that the chemical etchant attacks damaged regions faster than that for undamaged regions. 12 FIGUR. 5 :( a) ln track etch rate VT and ( b) ln bulk etch VB , plotted against T-1 (104 K-1) for the listed etchants for CR-39 detector. The slope of the straight lines gives value of the bulk activation energy ET and, EB respectively a b Kirkuk University Journal /Scientific Studies (KUJSS)