Separation of Pygmy Dipole and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:math>Resonances in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Zr</mml:mi><mml:mprescripts /><mml:none /><mml:mn>90</mml:mn></mml:mmultiscripts></mml:math>by a High-Resolution Inelastic Proton Scattering Near 0°

Iwamoto, Chihiro; Utsunomiya, H.; Tamii, A.; Akimune, H.; Nakada, H.; Shima, T.; Yamagata, T.; Kawabata, T.; Fujita, Y.; Matsubara, Hiroaki; Shimbara, Y.; Nagashima, M.; Suzuki, Tomokazu; Fujita, H.; Sakuda, M.; Mori, T.; Izumi, Takao; Okamoto, A.; Kondo, Takeo; Bilgier, B.; Kozer, H. C.; Lui, Y.‐W.; Hatanaka, K.

doi:10.1103/physrevlett.108.262501

Cited by 51 publications

(24 citation statements)

References 28 publications

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“…Similarly, the electromagnetic character of the increased strength for E γ > 4 MeV is also uncertain. In a recent study of the (p,p ) 90 Zr reaction [36], the authors find comparable cross sections for E1 and M1 resonances centered at excitation energies of 9.15 and 9.53 MeV, respectively. The former was interpreted as an E1 PDR, and the latter as an M1 spin-flip resonance with energy centroid and width following the systematics in RIPL-3 (the Reference Input Parameter Library at IAEA) [27] reasonably well.…”

Section: Gamma-ray Strength Functionsmentioning

confidence: 94%

Pygmy resonance and low-energy enhancement in theγ-ray strength functions of Pd isotopes

et al. 2014

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Background: An unexpected enhancement in the γ -ray strength function, as compared to the low-energy tail of the giant dipole resonance (GDR), has been observed for Sc, Ti, V, Fe, and Mo isotopes for E γ < 4 MeV. This enhancement was not observed in subsequent analyses on Sn isotopes, but a pygmy dipole resonance (PDR) centered at E γ ≈ 8 MeV was however detected. The γ -ray strength functions measured for Cd isotopes exhibit both features over the range of isotopes, with the low-energy enhancement decreasing and PDR strength increasing as a function of neutron number. This suggests a transitional region for the onset of low-energy enhancement, and also that the PDR strength depends on the number of neutrons. Purpose: The γ -ray strength functions of 105-108 Pd have been measured in order to further explore the proposed transitional region. Method: Experimental data were obtained at the Oslo Cyclotron Laboratory by using the charged particle reactions ( 3 He, 3 He γ ) and ( 3 He, αγ ) on 106,108 Pd target foils. Particle-γ coincidence measurements provided information on initial excitation energies and the corresponding γ -ray spectra, which were used to extract the level densities and γ -ray strength functions according to the Oslo method. Results: The γ -ray strength functions indicate a sudden increase in magnitude for E γ > 4 MeV, which is interpreted as a PDR centered at E γ ≈ 8 MeV. An enhanced γ -ray strength at low energies is also observed for 105 Pd, which is the lightest isotope measured in this work. Conclusions: A PDR is clearly identified in the γ -ray strength functions of 105-108 Pd, and a low-energy enhancement is observed for 105 Pd. Further, the results correspond and agree very well with the observations from the Cd isotopes, and support the suggested transitional region for the onset of low-energy enhancement with decreasing mass number. The neutron number dependency of the PDR strength is also evident.

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Section: Gamma-ray Strength Functionsmentioning

confidence: 94%

Pygmy resonance and low-energy enhancement in theγ-ray strength functions of Pd isotopes

et al. 2014

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“…The accuracy is quite good and would make a strong constraint on model parameters and the prediction of neutron star properties, supernova explosion dynamics, and many other interesting astrophysical predictions. Beyond these results we note that the experimental data can also be applied for pygmy dipole resonance strength distribution [10,26], spin-M 1 strength distribution [27], fine-structure and level density of the E1 strength by using statistical methods [28], and for gamma-ray strength function.…”

Section: Discussionmentioning

confidence: 83%

Studies of Electric Dipole Response in Nuclei Using the Scattering of Polarized Protons

Tamii¹

2013

Acta Phys. Pol. B

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The electric dipole (E1) response of 208 Pb has been precisely determined by proton inelastic scattering measurement at very forward angles. The electric dipole polarizability, which is an inversely energy-weighted sum-rule of the electric dipole strength, has been extracted as 20.1±0.6 fm 3 . The data has been used to constrain the neutron skin thickness of 208 Pb as 0.168 ± 0.22 fm and the slope parameter of the symmetry energy as L = 46 ± 15 MeV. The determination of the slope parameter is important for nuclear physics as well as for astrophysical simulations related to neutron stars.

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“…Experiments exploring Coulomb excitation, and polarized proton scattering off neutron-rich nuclei to extract the dipole polarizability and its relation to the slope parameter have been reported in a several publications in Refs. [129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148], just to cite a few of them. To date, there is a large variation in the measurements of α D in the order of 20-30%.…”

Section: Dipole Polarizabilitymentioning

confidence: 99%

Pygmy resonances and symmetry energy

Bertulani

2019

Eur. Phys. J. A

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I present a brief summary of the first three decades of studies of pygmy resonances in nuclei and their relation to the symmetry energy of nuclear matter. I discuss the first experiments and theories dedicated to study the electromagnetic response in halo nuclei and how a low energy peak was initially identified as a candidate for the pygmy resonance. This is followed by the description of a collective state in medium heavy and heavy nuclei which was definitely identified as a pygmy resonance. The role of the slope parameter of the symmetry energy in determining the properties of neutron stars is stressed. The theoretical and experimental information collected on pygmy resonances, neutron skins, and the numerous correlations found with the slope parameter is briefly reviewed. PACS. 25.20.-x Photonuclear reactions -26.60.+c Nuclear matter aspects of neutron starsTo the memory of Pier Francesco Bortignon

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Separation of Pygmy Dipole andM1Resonances inZr90by a High-Resolution Inelastic Proton Scattering Near 0°

Cited by 51 publications

References 28 publications

Pygmy resonance and low-energy enhancement in theγ-ray strength functions of Pd isotopes

Pygmy resonance and low-energy enhancement in theγ-ray strength functions of Pd isotopes

Studies of Electric Dipole Response in Nuclei Using the Scattering of Polarized Protons

Pygmy resonances and symmetry energy

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