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HK: Physik der Hadronen und Kerne

HK 32: Kernphysik/Spektroskopie

HK 32.3: Vortrag

Dienstag, 8. März 2005, 17:30–17:45, TU MA005

Proton Induced Fragmentation of Ni, Nb, and Au Nuclei — •Borys Piskor-Ignatowicz — Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich, Germany — M. Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, 30059 Kraków, Poland

The double differential cross sections dσ/dEdΩ for proton induced fragmentation of Ni, Nb, and Au nuclei have been measured by the PISA (Proton Induced SpAllation) collaboration. Thin (∼ 300 µg/cm²), selfsupporting targets have been irradiated by 1.2, 1.9 and 2.5 GeV internal proton beam of the COSY accelerator of the Forschungszentrum Jülich. Reaction products were registered by Bragg curve detectors, cooled silicon detectors and phoswich detectors. The apparatus enabled to identify the charge and mass of light charged particles (H and He ions) as well as intermediate mass fragments up to Z=6. Heavier ejectiles (with Z < 14) were only Z - identified. Preliminary analysis of the data shows that two contributions can be observed for all scattering angles and all observed reaction products: one of them seems to correspond to evaporation of particles from excited remnant nucleus of the fast intranuclear cascade of nucleon-nucleon collisions whereas another one is connected with isotropic emission of fragments from the fast, hot source which is significantly smaller than the target nucleus. The latter mechanism becomes increasingly more important for heavier reaction products. The quantitative analysis of the data is expected to give more detailed information on the reaction mechanism, especially as a function of the target mass and incident proton energy.