Effects of Non-Zero Spin in Sub-Barrier Fusion Involving Odd Mass Nuclei: The Case of 36S + 50Ti, 51V

International audience; A detailed comparative study of the sub-barrier fusion of the two near-by systems ^36S + ^50Ti, ^51V was performed at the National Laboratories of Legnaro (INFN). We aimed to investigate the possible effect of the non-zero spin of the ground state of the ^51V nucleus on the sub-barrier excitation function, and in particular on the shape of the barrier distribution. The comparison of the exctiation functions and barrier distributions highlighted a very similar behavior, down to the level of 20–30 µb. Coupled-channels calculations have been performed including the low energy excitations of both projectile and targets and the results are in very good agreement with the data. This indicates that the low-lying levels in ^51V can be interpreted in the weak-coupling scheme and that the extra proton in the f_7/2 shell does not have a significant influence on sub-barrier fusion

90-річчя члена-кореспондента НАН України Г.К. Степанковської

The p(T)-differential production cross section of electrons from semileptonic decays of heavy-flavor hadrons has been measured at midrapidity in proton-proton collisions at root s = 2.76 TeV in the transverse momentum range 0.5 < p(T) < 12 GeV/c with the ALICE detector at the LHC. The analysis was performed using minimum bias events and events triggered by the electromagnetic calorimeter. Predictions from perturbative QCD calculations agree with the data within the theoretical and experimental uncertainties

Sub-barrier fusion of (36)S+(64)Ni and other medium-light systems

Sub-barrier fusion cross sections of (36)S + (64)Ni have been measured down to similar or equal to 3 mu b. The logarithmic slope of the fusion excitation function has a steep rise in the barrier region with decreasing energy and saturates at lower energies. The data can be reproduced within the coupled-channels model using a Woods-Saxon potential with a large diffuseness. The slope saturation is analogous to what has been observed for (36)S, (48)Ca + (48)Ca, while for heavier systems the slope increases steadily below the barrier

Fusion of 40Ca+124Sn around the Coulomb barrier

Fusion-evaporation cross sections of View the 40Ca + 124Sn have been measured with good precision and the barrier distribution extracted, following a complementary experiment on multinucleon transfer on the same system. The completeness of the data allows to constrain the fusion calculations concerning the effect of transfer coupling. The measured cross sections are strongly enhanced below the barrier compared to the one-dimensional barrier penetration estimate and the “barrier distribution” is broad with no clear peak structure. Those features, together with transfer Q-values and cross sections make this system very similar to View the 40Ca + 96Zr where there were also hints of significant transfer effects. Simplified coupled-channel calculations fail to reproduce the low energy tail of the data, although the barrier distribution is qualitatively reproduced. At a few energies, also the fusion of View the 40Ca + 116Sn has been measured and found to be very similar to the 124Sn case

The influence of the 2-neutron elastic transfer on the fusion of 42Ca + 40Ca

Strong coupling to a single channel with zero Q-value is predicted to produce a characteristic fusion barrier distribution with two peaks, one on each side of the original uncoupled Coulomb barrier. In practical cases, only coupling to an elastic transfer channel may produce such a distribution which, however, has never been observed sofar, probably because low-lying surface vibrations usually have a dominant role, and this may obscure the two-peak structure. The case of the two-neutron (2n) elastic transfer in 42Ca + 40Ca is particularly attractive, because of the relatively rigid nature of the two nuclei. We have measured the fusion excitation function of this system using the 42Ca beam of the XTU Tandem of LNL on a thin 40Ca target enriched to 99.96% in mass 40. Cross sections have been measured down to 641 mb. The extracted barrier distribution shows clearly two main peaks. We have performed preliminary CC calculations where the 2+ coupling strengths have been taken from the literature and the schematic 2n pair transfer form factor has been used, with a deformation length \u3b4t= 0.39 fm. The excitation function is well reproduced by the calculation including the 2n transfer channel. However, including the octupole excitations destroys the agreement