Experiments on multiphonon states with proton–neutron mixed symmetry in vibrational nuclei

Pietralla, N.; Brentano, P. von; Lisetskiy, A. F.

doi:10.1016/j.ppnp.2007.08.002

Cited by 143 publications

(26 citation statements)

References 166 publications

(494 reference statements)

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“…Since then, they were systematically identified and studied in several other nuclei in the vicinity of the N = 50 and N = 82 shell closures. A review may be found in [39,40]. Those reviews report also the theoretical investigations carried out within a restricted shell model scheme [41] and, more thoroughly, in the microscopic quasiparticle-phonon model (QPM) [42,43].…”

Section: B Analysis Of the Resultsmentioning

confidence: 99%

Matrix diagonalization algorithm and its applicability to the nuclear shell model

et al. 2011

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An importance-sampling iterative algorithm for diagonalizing shell model Hamiltonian matrices is reviewed and implemented in a spin uncoupled basis. Shell model spaces of dimensions up to N≲109 are considered. The analysis shows that about 10% of the basis states are enough to bring the eigenvalues to convergence. This fraction of states, however, is insufficient to lead to convergence of the transition strengths, thereby limiting the applicability of the method to not too large spaces. In its domain of validity, the method yields a large number of eigensolutions and can be usefully adopted for rather complete studies of low-energy spectroscopy. This is done here for 132,134Xe isotopes. The calculation yields spectra and electromagnetic responses in fairly good agreement with the available experimental data and unveils the properties of the low-energy states of these isotopes, including their proton-neutron symmetry

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Section: B Analysis Of the Resultsmentioning

confidence: 99%

Matrix diagonalization algorithm and its applicability to the nuclear shell model

et al. 2011

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“…Recent studies [14,15,[47][48][49][50] show that in several N = 52 and N = 54 nuclei, so-called mixed symmetry states (proton-neutron isovector excitations of vibrational nature) have been observed. Such states may serve as a sensitive probe of the interplay between the proton-neutron degrees of freedom.…”

Section: Some Considerations On Feeding Patterns In Mntmentioning

confidence: 99%

Selective properties of neutron transfer reactions in the 90Zr + 208Pb system for the population of excited states in zirconium isotopes

et al. 2015

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Nuclei produced via multineutron transfer channels have been studied in 90Zr + 208Pb close to the Coulomb barrier energy in a fragment-γ coincident measurement employing the PRISMA magnetic spectrometer coupled to the CLARA γ-array. The selective properties of the reaction mechanism have been discussed in terms of states and their strength excited in the neutron transfer channels leading to 89-94Zr isotopes. A strong population of yrast states, with energies up to ~7.5 MeV has been observed. © 2015 Elsevier B.V

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“…This level is associated with the [2 + 1 ⊗ 2 + ms ] 1 + two-phonon level. The coupling of the first excited 2 + 1 level, associated with a symmetric coupling of proton and neutron excitations, and the 2 + ms mixed-symmetry state results in a quintuplet of levels with J π = 1 + − 4 + [40,41]. Because the 2 + ms represents an out-of-phase motion of valence proton and valence neutron degrees of freedom, this kind of excitation is not present in semimagic nuclei.…”

Section: -16mentioning

confidence: 99%

“…Below this energy the debris of the original 1p1h spin-flip excitations is found. Because the Ni isotopes are closed-shell nuclei, no orbital M1 strength owing to the [2 + 1 ⊗ 2 + ms ] 1 + coupling is expected [30,40,41]. The latter represents a two-phonon excitation of the first excited 2 + 1 level, corresponding to a symmetric coupling of proton and neutron components in the wave function and the so-called mixed-symmetry 2 + ms state corresponding to an antisymmetric coupling of proton and neutron components.…”

Section: Introductionmentioning

confidence: 99%

Photoresponse of60Ni below 10-MeV excitation energy: Evolution of dipole resonances infp-shell nuclei nearN=Z<

et al. 2013

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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 60 Ni 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 (γ, γ ) nuclear resonance fluorescence technique with unpolarized continuous bremsstrahlung as well as with fully linearly polarized, quasimonochromatic, Comptonbackscattered 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 [ B(E1) ↑= (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 [ B(E1) ↑= (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) ↑ strength of these structures accumulates to 3.94(27)μ 2 N .

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Experiments on multiphonon states with proton–neutron mixed symmetry in vibrational nuclei

Cited by 143 publications

References 166 publications

Matrix diagonalization algorithm and its applicability to the nuclear shell model

Matrix diagonalization algorithm and its applicability to the nuclear shell model

Selective properties of neutron transfer reactions in the 90Zr + 208Pb system for the population of excited states in zirconium isotopes

Photoresponse of60Ni below 10-MeV excitation energy: Evolution of dipole resonances infp-shell nuclei nearN=Z<

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