Isospin character of transitions to bound states inPb204,206,208

Abstract

We have measured the scattering of 375-MeV ' 0 ions by isotopes of ' ' Pb to investigate the isospin character of transitions to low-lying 2+ and 3 states. The data were analyzed using the deformed optical potential model. The 2+ collective strength, which is concentrated in a single state at 4.085 MeV in Pb, is observed to fragment in both Pb and Pb. The differential cross sections for excitation of the collective 2+ and 3 states are well reproduced by model calculations in which it is assumed that M"/M~= N /Z (i.e., isoscalar character). Angular distributions for the lowest-lying 2+ states in ' Pb are significantly different from those for the higher-lying collective 2+ states, and can be reproduced with M"/M~= 2.5. The data are compared with random-phase-approximation calculations including pairing, and good agreement is found within estimated uncertainties.

Isospin Character of Low-Lying Pygmy Dipole States inPb208via Inelastic Scattering ofOCrespi1, Bracco2, Nicolini3 et al. 2014Phys. Rev. Lett.653260View full textAdd to dashboardCite

“…767 fm (the radii and diffuseness of the real and imaginary parts) and r C ¼ 1.20 fm (the Coulomb radius parameter). They are in general good agreement with a previous measurement at a similar energy [15,25].…”

“…It is clear from the good agreement with the data on an absolute scale (no further normalization) that the deformed potential does an excellent job. The results for 2 þ and 3 − states are consistent with a measurement at 375 MeV [25]. For the 3 − state a hindrance factor was needed when it was excited with a beam energy of 84 MeV=u [28].…”

Isospin Character of Low-lying Pygmy Dipole States Probed via Inelastic Scattering of $^{17}$O

“…The optical model parameters of Saxon-Woods potentials providing the best fit to the data used correspond to V = 40.0 MeV, W = 42.5 MeV (with V and W the depth of the real and imaginary potentials), r v = r W = 1.15 fm, a V = a W = 0.767 fm (the radii and diffuseness of the real and imaginary parts) and r C = 1.20 fm (the Coulomb radius parameter). These are consistent with previous measurements at similar energy [14,15]. The differential cross section was determined for the 3 − at 2613 keV and it is shown in the bottom panel of [deg] 17 O+ 208 Pb elastic data.…”

Multitude of2+discrete states inSn124observed via the(O17Pellegri1, Bracco2, Tsoneva3 et al. 2015Phys. Rev. C272180View full textAdd to dashboardCite

“…Although the fulfillment of this condition is often considered as a manifestation of isoscalar [12,13] while for the unknown states a tentative assignment of the corresponding B(E2) ↑ was done. This was obtained from the relation between B(E2) ↑ and M n /M p [22,23] and assuming M n /M p = N/Z. It was already seen in [5] that the deformed potential model is able to reproduce well the experimental data, with the exception of the 1 − states.…”