The excitation of the Dynamical Dipole mode along the fusion path was investigated for the first time in the formation of a heavy composite system in the A∼190 mass region, in fusion-evaporation and ...fission events. The composite system was formed at identical conditions of excitation energy and spin from two reactions with different charge asymmetry: the charge asymmetric 40Ca + 152Sm and the nearly charge symmetric 48Ca + 144Sm at Elab=11 and 10.1 MeV/nucleon, respectively. In this paper, we report the results on fusion evaporation events and the preliminary analysis on fission channel.
The scattering process of weakly-bound nuclei at Coulomb barrier energies provides deep insights on the reaction dynamics induced by exotic nuclei. Within this framework, we measured for the first ...time the scattering process of the short-lived Radioactive Ion Beam (RIB) 8B (Sp = 0.1375 MeV) from a 208Pb target at 50 MeV beam energy. The 8B RIB was produced by means of the in-flight facility CRIB (RIKEN, Japan) with an average intensity on target of 10 kHz and a purity about 25%. Elastically scattering ions were detected in the angular range θc.m. = 10°-160° by means of the detector array EXPADES. A preliminary optical model analysis indicates a total reaction cross section of about 1 b, a value, once reduced, 2-3 times larger than those obtained for the reactions induced by the stable weakly-bound projectiles 6,7Li on a 208Pb target in the energy range around the Coulomb barrier.
In AGB environment, fluorine and sodium abundances are still matter of debate. About 19F (only stable isotope of fluorine), its abundance in the universe is strictly related to standard and ...extra-mixing processes taking place inside AGB-stars, that are considered to be the most important sites for its production. Nevertheless the way in which it is destroyed is far from being well understood. On the other hand, 23Na presence in Globular Clusters, along with is well-known anticorrelation with oxygen has made clear that this element must be produced in previous generations stars, and intermediatemass AGB stars are one of the possible candidates for its production. For this reason we studied the 19F(α,p)22Ne and 23Na(p,α)20Ne reactions in the energy range of relevance for astrophysics via the Trojan Horse Method (THM), using the three-body reactions 6Li(19F, p22Ne)d and 23Na(d, pn)20Ne.
The
19
F(p,
α
)
16
O reaction is of paramount importance for understanding the fluorine abundance in the outer layers of asymptotic giant branch (AGB) stars and it might also play a role in ...hydrogen-deficient post-AGB star nucleosynthesis. Theoretical models overestimate F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the reactions involved in the fluorine nucleosynthesis. In the last years, new direct and indirect measurements improved significantly the knowledge of the
19
F(p,
α
0
)
16
O cross section at deeply sub-Coulomb energies (below 0.8 MeV). Those data are larger by a factor of about 1.4 with respect to the previous data reported in the NACRE compilation in the energy region 0.6–0.8 MeV. In order to solve these discrepancies, here we present a new direct experiment performed using a silicon strip detector array (LHASA – Large High-resolution Array of Silicon for Astrophysics). Our results clearly confirm the trend of the latest experimental data in the energy region of interest, pointing towards a larger S-factor value than the one reported in the NACRE compilation.
Neutron induced reactions are fundamental for the nucleosynthesis of elements in the universe. Indeed, to correctly study the reactions involved in the well-known s-process in stars, which produce ...about half of the elements beyond the iron peak, it is mandatory to know the neutron abundance available in those stars. The
17
O(n, a)
14
C reaction is one of the so-called “neutron poisons” for the pro- cess and it could play an important role in the balance of the neutron abundance. The reaction is therefore investigated in the energy range of astrophysical inter- est between 0 and 350 keV in the center of mass by applying the Trojan Horse Method to the three body reaction
2
H(
17
O, a
14
C)H.
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