Forward-to-backward asymmetry of the (<i>γ</i>,n) reaction in the energy range 20<i>–</i>30 MeV

Murakami, T.; Halpern, I.; Storm, D W; Debevec, P. T.; Morford, L. J.; Wender, S.A.; Dowell, D. H.

doi:10.1103/physrevc.35.479

Cited by 22 publications

(7 citation statements)

References 33 publications

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“…Although there is evidence for its existence in a number of nuclei, the systematics of the isovector giant quadrupole resonance (IVGQR) have yet to be well established. This is particularly true in heavier nuclei, and the published reports of measurements of the strength distributions of the IVGQR in the lead region are quite inconsistent [3,[11][12][13][14][15][16][17][18][19][20][21]. There is reasonable agreement on the location of the isovector El resonance at an excitation in the vicinity of 21 to 24 MeV, but reported strengths range between 0 and 1.4 times the isovector quadrupole sum rule (IVQSR), and reported widths between 3.5 and 10 MeV.…”

mentioning

confidence: 99%

IsovectorE2 resonance inPb208

1992

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Polarization asymmetries observed in elastic tagged photon scattering at excitations between 16 and 30 MeV were used to identify the isovector giant electric quadrupole resonance in 208 Pb through its interference with underlying electric dipole strength. Resonance parameters reflecting the distribution of the El (T~\) transition strength were extracted in a manner that has minimal sensitivity to uncertainties in the Delbruck amplitudes or in the q dependence of the modified Thomson amplitudes. The isovector £2 resonance was found at an excitation of 20.2 ±0.5 MeV, with a width of 5.5 ±0.5 MeV, and a strength corresponding to 1.4 ± 0.3 times the isovector quadrupole sum rule. PACS numbers: 24.30.Cz, 24.70. +s, 25.20.Dc, 27.80.+W

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mentioning

confidence: 99%

IsovectorE2 resonance inPb208

1992

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“…7 and 8, respectively, together with the corresponding experimental data of Ref. [6]. The calculated cross section dσ (ω,55 • )/d n is somewhat overestimated (Fig.…”

Section: Reactions Accompanied By Excitation Of Ivgqrmentioning

confidence: 50%

“…The calculated peak energy of 21.8 MeV and total width of 4.4 MeV are in agreement with corresponding data of Refs. [3,6]. The first moment of the strength function (δ) ωS (−) 2 (ω)dω calculated for the large energy interval δ = 7.5 to 37.5 MeV is found to …”

Section: Reactions Accompanied By Excitation Of Ivgqrmentioning

confidence: 91%

“…Usually, the asymmetry of the angular distribution of the partial (γ,n) reaction, leading to population of a neutron-hole state μ −1 of the product nucleus, is described by the quantity α μ (ω,θ 1 ) defined as follows [6]:…”

Section: Reactions Accompanied By Excitation Of Ivgqrmentioning

confidence: 99%

“…[5] and references therein). The excitation of the IVGQR was also included in the DSD model [6]. Within this model a number of phenomenological quantities are used.…”

Section: Introductionmentioning

confidence: 99%

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Description of the simplest photonuclear reactions within the particle-hole dispersive optical model

Tulupov

Urin

2014

Phys. Rev. C

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A recently developed particle-hole dispersive optical model is applied to describe the cross sections of photoabsorption, direct + semidirect photoneutron and inverse reactions accompanied by excitation of the isovector giant dipole and quadrupole resonances in medium-heavy-mass spherical nuclei. The model is an extension of the standard and nonstandard versions of the continuum-random-phase approximation by including the spreading effect in a phenomenological way. It contains the following ingredients: the Landau-Migdal particle-hole interaction and a phenomenological mean field consistent with this interaction, isovector velocity-dependent forces taken in the simplest form and the imaginary part of an effective single-particle optical-model potential determining the corresponding dispersive part. All the model parameters are taken from the other data and from the description of photoabsorption, while the direct + semidirect photoneutron and inverse reactions are described without the use of specific adjustable parameters. Calculation results obtained for a few neutron-closed-shell nuclei are compared with the corresponding experimental data.

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Excitation and photon decay of giant multipole resonances — the role and future of medium-energy heavy ions

Bertrand¹,

Beene²,

Hören³

1988

Nuclear Physics A

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Inelastic scattering of mrdium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which Is Indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon "0 projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of che isoscalar giant quadrupole and isovector giant dipols resonances, are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the J0fi Pb isovector quadrupole resonance using its gamma decay are presented.

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Forward-to-backward asymmetry of the (γ,n) reaction in the energy range 20–30 MeV

Cited by 22 publications

References 33 publications

IsovectorE2 resonance inPb208

IsovectorE2 resonance inPb208

Description of the simplest photonuclear reactions within the particle-hole dispersive optical model

Excitation and photon decay of giant multipole resonances — the role and future of medium-energy heavy ions

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