Role of isospin in the statistical decay of the giant dipole resonance built on excited states

Harakeh, Mohsen; Dowell, D. H.; Feldman, G.; Garman, Elspeth F.; Loveman, R. A.; Osborne, J.L.; Snover, K. A.

doi:10.1016/0370-2693(86)90167-x

Cited by 62 publications

(45 citation statements)

References 24 publications

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“…Previous studies of the 12 C( 16 O,γ) 28 Si reaction at higher energies, aiming at measuring the isospin mixing in the 28 Si excitation energy region around 35 MeV, discussed the reaction mechanism in terms of populating the giant dipole resonance (GDR) built on excited states [20]. It might be that in our studies, the giant quadrupole resonance (GQR) is excited, built on the 24 Mg prolate ground state for 12 C+ 12 C [21] and on the prolate excited band in the case of 12 C+ 16 O.…”

Section: Resultsmentioning

confidence: 99%

Search for²⁸Si cluster states through the¹²C+¹⁶O radiative capture

Courtin

Goasduff

Haas

et al. 2013

J. Phys.: Conf. Ser.

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• spectrometer and the associated BGO array. The most remarquable result is the previously unobserved decay path through 28 Si doorway states of energies around 12 MeV leading to the measurement of new capture crosssections. The feeding of specific, deformed states in 28 Si from the resonances is discussed, as well as the selective feeding of 1 + T=1 states around 11 MeV. IntroductionThe occurence of α clusters in light nuclei is a well established phenomenon known to occur close to their α-decay thresholds, as described by Horiuchi and Ikeda in the late 1960s [1]. As examples of light cluster nuclei, we shall mention here briefly the 8 Be nucleus, which ground state (g.s.) decays into 2 α particles and the 12 C sub-closed shell nucleus which first excited 0 + state is located at 7.65 MeV, near the 8 Be+α fusion threshold. This state, that has been identified by Hoyle to play a major role in the nucleosynthesis of 12 C, is not described by shellmodel calculations but rather by cluster models. The identification of the cluster band built on this 'Hoyle' state is still a challenging goal for experimentalists. In 16 O a clear alpha cluster band has been identified based on a 0 + excited state at 6.05 MeV, a 2 + state at 6.92 MeV and a 2 + state at 10.36 MeV, with large reduced transition probabilities B(E2)(2 + to 0 + )= 27 W.u. and B(E2)(4 + to 2 + )= 65 W.u. A shell-model description of this very deformed band requires 4p-4h (4 particle-4 hole) excitations to be taken into account. What heavier ions are concerned, in the sd shell, in addition to α clusters, 12 C and 16 O are the elementary bricks for the occurence of cluster structures in 24 Mg( 12 C-12 C) and 28 Si( 12 C-16 O). One of the most striking results obtained in the early studies of heavy-ion collisions is the observation of resonant structures in the reaction cross-sections (elastic, inelastic and

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Section: Resultsmentioning

confidence: 99%

Search for²⁸Si cluster states through the¹²C+¹⁶O radiative capture

Courtin

Goasduff

Haas

et al. 2013

J. Phys.: Conf. Ser.

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“…The original version of the CASCADE code was first modified by Harakeh [20] and later on by the Washington University group [19], according to the formalism of Harney, Richter, and Weidenmüller [26].…”

Section: B 80 Zr: Isospin Mixingmentioning

confidence: 99%

“…The isospinsymmetry breaking can be observed through decays which would be inhibited by isospin selection rules. This is the case of the electric dipole transition (i.e., E1 transition) from selfconjugate nuclei in an I = 0 configuration [18][19][20][21][22][23]. Because the IVGDR exhausts the major part of the energy-weighted sum rule for an E1 transition, this resonance is a powerful tool to observe and quantify the isospin-mixing effects.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the isovector giant dipole resonance inZr80andRb81

Ceruti¹,

Camera²,

Bracco³

et al. 2017

Phys. Rev. C

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The isovector giant dipole resonance (IVGDR) γ decay was measured in the compound nuclei 80 81 Rb at the same excitation energy. The IVGDR parameters extracted from the analysis were compared with the ones found at higher excitation energy (E * = 83 MeV). The comparison allows one to observe two different nuclear mechanisms: (i) the IVGDR intrinsic width remains constant with the excitation energy in the nucleus 81 Rb; (ii) the isospin-violating spreading width (i.e., Coulomb spreading width) remains constant with the excitation energy in the nucleus 80 Zr. The experimental setup used for the γ -ray detection was composed by the AGATA demonstrator array coupled to the large-volume LaBr 3 :Ce detectors of the HECTOR + array.

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“…in each case. The codes that will be considered here are PACE2 [3], LILITA [20,21] and CASCADE [6,22]. (It is worth mentioning that two mistakes were discovered and corrected in the neutron optical-model potential parameters appearing in the PACE2 source code: a).-The coefficient of the E 2 term in V was 0.0018, corrected to 0.00118 (see [23], [24]).…”

Section: Absolute Normalization Of Datamentioning

confidence: 99%

“…The CASCIP version [22] of the latter code, which treats isospin and parity exactly, was used here. As a first step, the mass tables used by the three codes were unified to the AME12 table [27].…”

Section: Absolute Normalization Of Datamentioning

confidence: 99%

Above-barrier fusion enhancement of proton-halo systems

et al. 2016

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Previously reported data for fusion of the 8 B + ( 58 Ni, 28 Si) systems are critically reviewed. New α particle data from the fusion of 8 B + 58 Ni also are reported, but the paper is mostly based on using realistic calculations of well established codes to reanalyze the previous data. The influence of breakup protons on the evaporation proton measurements for the heavier system is found to be small at all energies except for the lowest one measured, and corrections are made for this process. Possible model dependencies in the deduced fusion cross sections are investigated using three different evaporation codes. The data sets for the 58 Ni and 28 Si targets are shown to be consistent with each other and with fusion enhancement up to energies that are greater than the Coulomb barrier V b (E c.m. < ∼ V b + 1.5×hω). This limit corresponds to 6.2 MeV above the barrier for the 58 Ni target. An important difference with the behaviour of neutron-halo systems is thus confirmed.PACS numbers: 25.60. Pj ,

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Role of isospin in the statistical decay of the giant dipole resonance built on excited states

Cited by 62 publications

References 24 publications

Search for²⁸Si cluster states through the¹²C+¹⁶O radiative capture

Search for²⁸Si cluster states through the¹²C+¹⁶O radiative capture

Experimental study of the isovector giant dipole resonance inZr80andRb81

Above-barrier fusion enhancement of proton-halo systems

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Role of isospin in the statistical decay of the giant dipole resonance built on excited states

Cited by 62 publications

References 24 publications

Search for28Si cluster states through the12C+16O radiative capture

Search for28Si cluster states through the12C+16O radiative capture

Experimental study of the isovector giant dipole resonance inZr80andRb81

Above-barrier fusion enhancement of proton-halo systems

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Product

Resources

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Search for²⁸Si cluster states through the¹²C+¹⁶O radiative capture

Search for²⁸Si cluster states through the¹²C+¹⁶O radiative capture