Stopping powers of havar for 1.6, 2.3 and 3.2 MeV/u heavy ions T. Alanko * , J. Hyv onen, V. Kyll  onen, J. R ais anen, A. Virtanen Department of Physics, University of Jyv askyl a, P.O. Box 35 (Y5), FIN-40351 Jyv askyl a, Finland Abstract Stopping powers of havar for 28;30 Si-, 36 Ar-, 54;56 Fe- and 80;84 Kr-ions with energies of 1.6, 2.3 and 3.2 MeV/u have been determined by a transmission technique. Sample foils are exposed to the direct beams. No previous data for havar with these ions have been published. The obtained results are brought together with literature havar data for 1 H-, 4 He-, 7 Li-, 11 B-, 12 C-, 14 N-, 16 O- and 127 I-ions at the same ion velocity. The experimental data are compared with the values predicted by the SRIM-2000 parametrization using BraggÕs rule. A systematic underestimation, by 6±23%, of the ex- perimental stopping powers was observed. The empirical correction scheme of Thwaites has been applied to the stopping power values obtained by the parametrization. The corrected values agree well with the present results. Also, the eective charge values of the various ions were deduced from the experimental set of data. Ó 2000 Elsevier Science B.V. All rights reserved. PACS: 34.50.Bw; 81.05.Bx Keywords: Stopping power; Heavy ions; Havar 1. Introduction The slowing down process of energetic heavy ions in materials has recently gained importance due to the applications of ion beam based char- acterization techniques. For the quanti®cation of all ion beam techniques, accurate stopping power data is of signi®cant importance. Up to date only limited experimental data for heavy ions can be found in the literature. Theoretical development of energy loss calculations require experimental data and the validity of these calculations for heavy ions needs to be further investigated. Using the transmission technique we have de- termined the stopping powers of havar, a cobalt based alloy, for 1.6, 2.3 and 3.2 MeV/u 28;30 Si-, 36 Ar-, 54;56 Fe- and 80;84 Kr-ions. The energies studied are relevant for ion beam techniques employing heavy ions. For the selected ions no previous experimental stopping power values of havar have been reported in the literature. A comparison with a widely used parametrization and model for stopping power is presented. The present values are brought together with havar stopping power data found from the literature for 1 H-, 4 He-, 7 Li-, 11 B-, 12 C-, 14 N-, 16 O- and 127 I-ions [1±4]. Nuclear Instruments and Methods in Physics Research B 161±163 (2000) 164±167 www.elsevier.nl/locate/nimb * Corresponding author. Tel.: +358-14-2602-390; fax: +358- 14-602-351. E-mail address: tommi.alanko@phys.jyu.® (T. Alanko). 0168-583X/00/$ - see front matter Ó 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X ( 9 9 ) 0 0 8 5 6 - 3