Calibration of CR-39 (DOP) detector module for indian cosmic ray experiment using accelerated beams

We are using CR-39 (DOP) detectors to study cosmic rays in the charge region Z = 2&#8722;26 in our Spacelab-3 experiment. We have exposed the detector samples to different accelerated beams He, C, N, O, Ne<SUP>20</SUP>, Ne<SUP>22</SUP>, Si, Cr, Fe, Ni and U of various energies. These exposed samples are etched in 6.25 N NaOH at 70&#176;C for different etching times. Different etched track parameters are measured to obtain minimum error in calculated V<SUB>t</SUB>/V<SUB>b</SUB> ratio. The obtained values of V<SUB>t</SUB>/V<SUB>b</SUB> are plotted against dE/dX as well as (Z&#8727;/&#946;)<SUP>2</SUP>. A non-linear curve of the form V<SUB>t</SUB>/V<SUB>b</SUB> = 1 + a(dE/dX) + b(dE/dX)<SUP>c</SUP> + d(dE/dX)<SUP>e</SUP> which has linear as well as power terms, is fitted using least square method. The possible charge resolution is calculated from the measured standard deviation. The curves between particle energy and V<SUB>t</SUB>/V<SUB>b</SUB> are drawn for different ions using suitable range energy relations for low energy region. The possible isotopic resolution is also discussed