Excitation of208Pbin light ion induced reactions and the two octupole phonon multiplet

Abstract

To identify the states of the 0 ϩ , 2 ϩ , 4 ϩ , and 6 ϩ two octupole phonon ͑TOP͒ multiplet in 208 Pb and their respective fragmentation inelastic proton, deuteron, and ␣ scattering has been measured in high energy resolution. Quantum numbers and spectroscopic factors of excited states up to 8 MeV are obtained from the 207 Pb(d,p) 208 Pb transfer reaction with vector polarized deuterons. From the comparison with literature, we conclude that up to E x ϭ6 MeV, essentially all states are resolved. The data are compared with recent calculations within the quasiparticle phonon model. For the lowest states the calculated energies are in excellent agreement with experiment. The calculated spectrum of 0 ϩ , 2 ϩ , 4 ϩ , and 6 ϩ states, which includes mixing with the TOP multiplet, is related to experimental states up to excitation energies above twice the excitation energy of the collective 3 1Ϫ state at E x ϭ5230 keV. The measured excitation strengths are consistent with the predicted fragmentation of the two octupole phonon states.

Anharmonicity of multi–octupole-phonon excitations inPb208: Analysis with multireference covariant density functional theory and subbarrier fusion ofO16Yao1, Hagino2 2016Phys. Rev. C172110View full textAdd to dashboardCite

“…Even though many of the TOP members have been identified, the multi-phonon excitations in 208 Pb have not yet been understood completely. This is the case especially for the nature of the TOP multiplets, which has been predicted to show a strong fragmentation [13][14][15].…”

“…Even though many of the TOP members have been identified, the multi-phonon excitations in 208 Pb have not yet been understood completely. This is the case especially for the nature of the TOP multiplets, which has been predicted to show a strong fragmentation [13][14][15].Incidentally, heavy-ion fusion reactions provide an alternative way to probe the multi-phonon excitations in atomic nuclei, which significantly affect the subbarrier fusion cross sections [16][17][18][19] as illustrated by coupled-channels calculations [16,20,21]. Previous coupled-channels calculations for the fusion reaction of 16 O+ 208 Pb based on multi-harmonic-phonon excitations fail to reproduce the observed energy dependence of fusion cross sections [22][23][24], and overestimate the height of the main peak in the so called fusion barrier distribution [25].…”

“…In the past decades, several experimental searches for the twooctupole-phonon (TOP) states in 208 Pb have been carried out [10][11][12][13]. Even though many of the TOP members have been identified, the multi-phonon excitations in 208 Pb have not yet been understood completely.…”

Complete Spectroscopy of negative parity states in208Pb with Ex< 6.3 MeV

“…The excitation energy in the SSM is derived from the masses of the nuclei 207 Tl,209 Bi,208 Pb and 207 Pb,209 Pb,208 Pb, the excitation energies of the particle states in 209 Bi,209 Pb, and the hole states in 207 Tl,207 Pb, for proton and neutron particle-hole configurations, respectively. Particle spectroscopy offers tools to determine some particle-hole components [1][2][3][4][5].…”

Two-phonon octupole excitation inGd146

“…In addition, candidates for the 2 + and 4 + members of the quartet at nearly harmonic energies have been proposed, but these identifications are based primarily on energy arguments and E1 transition rates; the signature cascade of E3 transitions was not observed [6]. Transfer reaction and inelastic light-ion scattering studies [7] support these assignments, but no clear candidate for the 6 + member in 208 Pb has been identified, although a number of experiments have been performed specifically to observe this excitation.…”