engleski

Study of the weak absorption in the collisions of carbon and oxygen nuclei in the energy range between 5 and 10 MeV per nucleon

U teškoinskim sudarima prevladava jaka apsorpcija koja vodi stvaranju složene jezgre. Pri nekim teškoinskim sudarima zatvorenih ili poluzatvorenih shell-modelskih ljusaka opažene su rezonantne (E>5 MeV po nukleonu) i refraktivne (E>10 MeV po nukleonu) pojave kao posljedica smanjene apsorpcije. Pojava nuklearne duge i pridruženih Airyevih oscilacija smanjuje neodređenosti optičkog potencijala i omogućuje njegovo određivanje za manje radijuse međudjelovanja nego što je to obično slučaj u teškoionskim sudarima. Refraktivne pojave proučavane su za sisteme ^16O+^12C i ^18O+^12C u energetskom rasponu između 5 i 10 MeV po nukleonu. Sva su mjerenja izvršena na tandem akceleratoru Vivitron u Strasbourgu. Dobiveni rezultati su uspoređeni s rezultatima reakcija ^16O+^16O i ^12C+^12C. Uspostavljena je veza između refraktivnih pojava i jezgra-jezgra potencijala za različite energije i sisteme, te ovisnost refraktivnih pojava o energiji snopa. Raspodjela masa, Q-spektri, kutne raspodjele, udarni presjeci integrirani po kutu, srednje vrijednosti transferirane energije i spina detektiranih fragmenata predstavljeni su za nekoliko binarnih kanala. Sve navedene varijable ukazuju na mehanizam orbitinga (a ne stvaranje složene jezgre) kao osnovni mehanizam reakcije. The established presence of strong absorption in the interaction between heavy ions leads to the compound-nucleus formation. In certain ight-heavy-ion collisions, involving the closed or semi-closed shell nuclei, the resonant (at E<5 MeV per nucleon) and refractive (at E>10 MeV per nucleon) phenomena have been observed. Such phenomena are connected with a weaker absorption and a small number of open channels. The observation of refractive effects, like the nuclear rainbow and associated Airy oscillations, determines the optical potentials with less ambiguity, and permits their extraction at smaller interaction radii than is usually the case in heavy-ion collisions. Refractive effects have been studied for the ^16O+^12C and ^18O+^12C systems in the energy range between 5 and 10 MeV per nucleon. These experiments were performed at the Strasbourg Vivitron tandem accelerator. All obtained results are compared with the ^16O+^16O and ^12C+^12C reactions. The evolution of refractive effects as a function of beam energy and the correlation between the refractive phenomena and the nucleus-nucleus potential at different energies and among different systems have been presented. The mass distributions, the Q-value spectra, the angular distributions, the angle-integrated cross sections, the mean values of transfered energy and spin of the fragments are extracted for several inelastic and transfer reactions. These features suggest the non-compound orbiting processes as the dominant reaction mechanism.

nuclear heavy-ion reactions at low energy; elastic; inelastic and transfer reactions;

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