6 research outputs found
Structure of high-lying levels populated in the 96Y → 96 Z r β decay
The nature of J = 1− levels of 96Zr below the -decay Q value of 96Y has been investigated in high-resolution -ray spectroscopy following the decay as well as in a campaign of inelastic photon scattering experiments. Branching ratios extracted from decay allow the absolute E1 excitation strength to be determined for levels populated in both reactions. The combined data represents a comprehensive approach to the wavefunction of 1− levels below the Q value, which are investigated in the theoretical approach of the Quasiparticle Phonon Model. This study clarifies the nuclear structure properties associated with the enhanced population of high-lying levels in the 96Ygs decay, one of the three most important contributors to the high-energy reactor antineutrino spectrum
High-resolution investigation of the Sb-121(p,t)Sb-119 reaction and quasiparticle-phonon model description
The Sb-121(p,t)Sb-119 reaction has been measured in a high-resolution experiment at an incident energy of 21 MeV. Accurate measurement of the (p,t) reaction angular distributions for the transitions to the levels of Sb-119 allows us to determine energies of 59 levels, 23 of which have been identified for the first time, and to assign the angular momentum transfer values and a well-defined range for the J values. DWBA analysis has been performed in a finite-range approximation, assuming a dineutron cluster pickup mechanism, by using conventional Woods-Saxon potentials for the entrance proton and exit triton channel. The present (p,t) data have been supplemented by microscopic calculations in the framework of the quasiparticle-phonon model, giving a reasonably good description of the experimental fragmentation of the integrated cross sections and the absence of (p,t) strength above 2.9 MeV
Sr-86 states homologous to the low-lying states of Rb-85
The structure of low-lying states in Rb-85 and highly excited states in Sr-86 has been studied within the framework of the shell model. The calculation predicts the occurrence of states in Sr-86 with a structure homologous to parent states in Rb-85, a phenomenon experimentally observed in other regions of the mass tabled via ((p) over right arrow, alpha) reactions
Photoresponse of 60Ni below 10-MeV excitation energy:evolution of dipole resonances in fp-shell nuclei near N=Z
Background: Within the last decade, below the giant dipole resonance the existence of a concentration of additional electric dipole strength has been established. This accumulation of low-lying E1 strength is commonly referred to as pygmy dipole resonance (PDR). Purpose: The photoresponse of Ni-60 has been investigated experimentally and theoretically to test the evolution of the PDR in a nucleus with only a small neutron excess. Furthermore, the isoscalar and isovector M1 resonances were investigated. Method: Spin-1 states were excited by exploiting the (gamma, gamma') nuclear resonance fluorescence technique with unpolarized continuous bremsstrahlung as well as with fully linearly polarized, quasimonochromatic, Compton-backscattered laser photons in the entrance channel of the reaction. Results: Up to 10 MeV a detailed picture of J = 1 levels was obtained. For the preponderant number of the individual levels spin and parity were firmly assigned. Furthermore, branching ratios, transition widths, and reduced B(E1) or B(M1) excitation probability were calculated from the measured scattering cross sections. A comparison with theoretical results obtained within the quasiparticle phonon model allows an insight into the microscopic structure of the observed states. Conclusions: Below 10 MeV the directly observed E1 strength [Sigma B(E1) up arrow = (153.8 +/- 9.5) e(2)(fm)(2)] exhausts 0.5% of the Thomas-Reiche-Kuhn sum rule. This value increases to 0.8% of the sum rule [Sigma B(E1) up arrow = (250.9 +/- 31.1) e(2)(fm)(2)] when indirectly observed branches to lower-lying levels are considered. Two accumulations of M1 excited spin-1 states near 8 and 9 MeV excitation energy are identified as isoscalar and isovector M1 resonances dominated by proton and neutron f(7/2) -> f(5/2) spin-flip excitations. The B(M1) up arrow strength of these structures accumulates to 3.94(27)mu(2)(N)