Bochum 2009 – wissenschaftliches Programm
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HK: Fachverband Hadronen und Kerne
HK 36: Nuclear Structure and Dynamics I
HK 36.3: Vortrag
Dienstag, 17. März 2009, 17:00–17:15, H-ZO 40
Even-odd effect in the yields from high-energy reactions — •M.Valentina Ricciardi1, Karl-Heinz Schmidt2, Aleksandra Kelic1, Fanny Rejmund2, and Christelle Schmitt3 — 1GSI, Darmstadt, Germany — 2GANIL, Caen, France — 3IPN, Lyon, France
In 2003, the analysis of experimental production cross-sections of the light products of the reaction 238U+Ti at 1 A GeV, measured at the FRS, GSI, revealed a very strong even-odd staggering, which in some cases amounted to 50 percent, a magnitude comparable to even-odd effects found in low-energy fission. The origin of this effect was explained on the basis of the statistical model of nuclear reaction, by carefully considering the appropriate nuclear-structure effects in binding energies and level densities.
In the meantime, a large amount of new experiments on nuclear reactions at high energy were performed at the FRS. The cross sections of the produced nuclei, fully identified in mass and atomic number, and kinematically separated to disentangle the different contributing reaction-mechanisms, also showed to be modulated by a complex and very strong even-odd structure. The new systematic analysis of the even-odd effect over a large range of nuclear reactions and nuclear systems, on one hand confirmed the expected behaviors for the light residual nuclei produced in high-energy reactions, on the other, revealed new and unexpected tendencies of the even-odd phenomenon in regions of the production yields up to now unexplored. The new features are discussed and possible explanations offered.