INVESTIGATION OF THE VERY HEAVY COSMIC ABUNDANCES AT SOURCE ESTIMATEDFROM BALLOON-BORNE PASSIVE-DETECTOR RESULTS OVER ALICE SPRINGS

A detailed study on the relative abundances of very heavy elements of cosmic rays with charges 10 less than or equal to Z less than or equal to 28 in the interstellar medium has been estimated from the results obtained from the balloon-borne passive-detector experiments flown for 32 hours from Alice Springs. The recovered CR-39 (HCB) detectors were etched for 96 hours in 7.5N NaOH solution at 80 degrees C. About 2126 elliptic etch pit cones were scanned from the 250 cm(2) area of the t rack detector and the chemical abundances of elements with charges 10 less than or equal to Z less than or equal to 28 above 2 GeV/n have be en estimated. We have adopted the charge-changing cross-sections calcu lated from the abrasion/ablation model after Norbury and duly fitted i n the slab model to account for the loss of intensity due to nuclear f ragmentation in the upper atmosphere. The predicted source composition is comparable with the derived result of Lezniak and Webber. Our resu lt on (Sc-Cr)/Fe flux ratio at 6.52 GeV/n energy is in accord with the results derived from the leaky-box model.