ud zi ¥ sk a , J . P a j¨k, Cz. Szy ma ¥sk i an d R. Szat ani k Instit ut e of Physi cs, O pole U ni versity , O leska 48, 45-052 Opole, Polan d A ngular distri buti ons of the positron annihil ati on quanta were measured for pure and hydrogenated palladi um samples def ormed by unia xi al tension up to di˜erent def ormation degrees. T he relative di˜erence curves, and the v alues of the R parameter characteri zing the dimensions of def ects trapping the positrons, w ere determined. It w as

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... d that for relative elongation s ranging from 1.9 to 3.5%, in both the pure and hydrogenated pallad iu m, the p ositrons are trapp ed in def ects larger than vacancy clusters. T he values of the R parameter for pure palladi um samples elongated up to 0.39, 0.77, and 1.5% indicate a dominant role of smaller def ects, like the vacancy clusters. PAC S numb ers: 78. 70. Bj