The energy loss straggling of ions in matter

C.C. MONTANARI; J. E. MIRAGLIA

Fort Worth, Texas

Congreso; 22st International Conference in the Application of Accelerators in Research and Industry; 2012

University of North Texas and Sandia National Laboratories

The energy loss straggling is an interesting parameter for the theoretical study. It represents a sensitive input for many calculations and computer simulations for material analysis of technological and biological interest (SIMNRA, SEICS) [1,2]. The nature of the dispersion in energy loss is statistical: when swift charged particles penetrate matter, they lose energy almost entirely through inelastic collisions with the electrons of the stopping material in a great number of collisional events, giving rise to the dispersion in the ion energy loss spectrum.    The measured straggling includes also the contribution due to surface roughness and inhomogeneity in the foil thickness [3-4], clear in some of the data in Yang compilation [5]. Since 1980, the straggling measurements began to take this effect into account [6], both in the sample preparation and in the final values. There are a great number of recent measurements from different laboratories and techniques that show less spread and a tendency to a single band. In this contribution we present theoretical results developed using a collective model for target electrons, the SLPA [7]. We will present our calculations for different ions and targets, together with a comparison with the available data. A scaling of the square energy loss straggling normalized to Bohr high energy limit is presented, which allows to represent is almost a single curve the straggling data and theoretical curves for different ions (H to B) and targets (Cu to Bi), and introduces the possibility of a simple universal function for the energy loss straggling.   [1] M Mayerl, Nucl. Instrum. Methods. Phys. Res. B 194, 177 (2002) [2] R Garcia-Molina et al, Phys. Med. Biol 56, 6475 (2011) [3] Y Kido, Phys. Rev. B 34, 73 (1986) [4] J C Eckardt and G. H. Lantschner, Thin Solid Films 249, 11 (1994) [5] Q Yang et al, Nucl. Instrum. Methods. Phys. Res. B 61, 149 (1991) [6] F Besenbacher et al, Nucl. Instrum. Methods 168, 1 (1980) [7] C C Montanari et al, Phys. Rev. A 75, 022903 (2007); Phys. Rev. A 79, 032903 (2009)