Abundance of Delta Resonances in 58Ni+58Ni Collisions between 1 and 2 AGeV
nucl-ex
/ Authors
FOPI Collaboration, B. Hong, N. Herrmann, J. L. Ritman, D. Best, A. Gobbi, K. D. Hildenbrand, M. Kirejczyk, Y. Leifels, C. Pinkenburg
and 52 more authors
W. Reisdorf, D. Schuell, U. Sodan, G. S. Wang, T. Wienold, J. P. Alard, V. Amouroux, N. Bastid, I. Belyaev, G. Berek, J. Biegansky, A. Buta, J. P. Coffin, P. Crochet, R. Dona, P. Dupieux, M. Eskef, P. Fintz, Z. Fodor, L. Fraysse, A. Genoux-Lubain, G. Goebels, G. Guillaume, E. Haefele
/ Abstract
Charged pion spectra measured in 58Ni-58Ni collisions at 1.06, 1.45 and 1.93 AGeV are interpreted in terms of a thermal model including the decay of Delta resonances. The transverse momentum spectra of pions are well reproduced by adding the pions originating from the Delta-resonance decay to the component of thermal pions, deduced from the high transverse momentum part of the pion spectra. About 10 and 18% of the nucleons are excited to Delta states at freeze-out for beam energies of 1 and 2 AGeV, respectively.