Measurements of the total photonuclear cross sections from 30 MeV to 140 MeV for Sn, Ce, Ta, Pb and U nuclei

Neutron skin thickness from the measured electric dipole polarizability inNi68,Sn120, andRoca-Maza1, Viñas2, Centelles3 et al. 2015Phys. Rev. C238322563View full textAdd to dashboardCite

“…Similarly, the two lower panels in the figure display the α D J-∆r np correlations in (c) 48 Ca and (d) 90 Zr, respectively. As in the previous subsection we find that both of the upper panels display a linear correlation that may be fitted as follows: (15) α D ( 90 Zr) = (1.1 ± 0.1 )+(0.24 ± 0.02)α D ( 208 Pb), (16) with the correlation coefficients of 0.82 for 48 Ca and 0.91 for 90 Zr, respectively. As in the case shown in Fig.…”

“…In the case of 68 Ni, as already explained, this region was not explored so no correction is needed 1 . For 120 Sn this contribution has an estimated value of 0.34 ± 0.08 fm 3 [22,23]. Thus, for a comparison with QRPA calculations, the value α D ( 120 Sn) = 8.93 ± 0.36 fm 3 of Ref.…”

“…In the high energy region above 30 MeV the experimental dipole strength may contain a non-negligible amount of contamination coming from non-resonant processes (the so-called quasi-deuteron effect [13,22]). These contributions should be removed from the experimental strength for a direct comparison with theoretical (Q)RPA results.…”

“…Based on the success of the 208 Pb experiment, the electric dipole strength of 120 Sn was recently measured at RCNP in the interval between 5 and 22 MeV [15]. Combining this new measurement with existing photo-absorption data up to 135 MeV [16], a value of α D ( 120 Sn) = 8.93 ± 0.36 fm 3 was obtained [15]. Finally, turning to exotic nuclei, the electric dipole response of the unstable 68 Ni isotope has been recently investigated at GSI using both Coulomb excitation in in-verse kinematics and by measuring the invariant mass in the one-and two-neutron decay channels [17,18].…”

“…Finally, using these selected models we obtain estimates for the neutron skin thickness of 68 Ni, 120 Sn, and 208 Pb, as well as constraints on the symmetry energy parameters. We should emphasize that the experimental values of the electric dipole polarizability for 120 Sn and 208 Pb contain a small, yet non-negligible, amount of contamination at higher energies caused by non-resonant processes; the so-called "quasi-deuteron" effect [13,22]. To be able to directly compare the measured values of α D against our theoretical predictions, these contributions have to be subtracted from the experimental strength.…”