Angular momentum dependence of the giant dipole resonance width in excited nuclei of mass

Chakrabarty, D. R.; Nanal, V.; Datar, V. M.; Kumar, Suresh; Mitra, A.; Mirgule, E. T.; Pillay, R. G.

doi:10.1016/j.nuclphysa.2006.02.012

Cited by 11 publications

(15 citation statements)

References 26 publications

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“…Even though the angular momentum of the compound nucleus 28 Si is higher than the critical angular momentum required for the Jacobi shape transition, the GDR lineshape is akin to a prolate deformed nucleus. Considering the present results for 28 Si and similar observation recently reported in 32 S, it is proposed that the nuclear orbiting phenomenon exhibited by α-cluster nuclei hinders the Jacobi shape transition. The present experimental results suggest a possibility to investigate the nuclear orbiting phenomenon using high energy γ-rays as a probe.…”

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confidence: 91%

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Study of the Jacobi shape transition in A≈30 nuclei

et al. 2018

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This paper reports the first observation of the Jacobi shape transition in 31 P using high energy γ-rays from the decay of giant dipole resonance (GDR) as a probe. The measured GDR spectrum in the decay of 31 P shows a distinct low energy component around 10 MeV, which is a clear signature of Corioli's splitting in a highly deformed rotating nucleus. Interestingly, a self-conjugate α-cluster nucleus 28 Si, populated at similar initial excitation energy and angular momentum, exhibits a vastly different GDR line shape. Even though the angular momentum of the compound nucleus 28 Si is higher than the critical angular momentum required for the Jacobi shape transition, the GDR lineshape is akin to a prolate deformed nucleus. Considering the present results for 28 Si and similar observation recently reported in 32 S, it is proposed that the nuclear orbiting phenomenon exhibited by α-cluster nuclei hinders the Jacobi shape transition. The present experimental results suggest a possibility to investigate the nuclear orbiting phenomenon using high energy γ-rays as a probe.Many body quantum systems like atomic nuclei provide a unique opportunity to explore a variety of phenomena arising due to interplay of different physical processes, particularly at high excitation energy (E * ) and angular momentum (J). One such interesting phenomenon is the Jacobi shape transition, where beyond a critical angular momentum (J C ), an abrupt shape change from non-collective oblate shape to collective triaxial or prolate shape takes place [1]. The study of exotic Jacobi shapes in nuclei has been a topic of considerable interest [2, 3]. The Jacobi shape transition is expected to occur in light and medium mass nuclei, where high rotational frequencies are achieved before the excited nucleus can undergo fission. Further, it is expected that the Jacobi shape transition should be a common feature over a wide range of nuclei. Experimentally, the Jacobi shape transition has been observed in a few light mass nuclei A ∼ 45 [4-7] via the γ-decay of giant dipole resonance (GDR). It is known that the GDR is the cleanest, and hence most extensively used, probe to study the properties of nuclei at high temperature (T ) and J [8]. The GDR can be understood macroscopically as an out-of-phase oscillation between protons and neutrons, and microscopically in terms of coherent particle-hole excitations. The GDR γ-emission occurs at the early stage of compound nucleus (CN) decay and can probe the nuclear shape. The GDR components corresponding to vibration along and perpendicular to the axis of rotation are differently affected by the Corioli's force. As a result the GDR strength function splits into multiple components with a narrow well separated peak around 8-10 MeV [4], which is an unambiguous signature of the Jacobi shape transition. It should be mentioned that the search for Jacobi shapes has also been made through studies of quasi-continuum gamma radiation [9]. However, indications of highly deformed shapes could not be uniquely ascribed to the Jacobi ...

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“…The M distribution is then converted to the fold (F ) distribution incorporating the BGO array efficiency and crosstalk probability as described in Ref. [32]. All three parameters, namely, P r , δ 1 and δ 2 are varied to fit the experimentally observed fold distribution.…”

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Study of the Jacobi shape transition in A≈30 nuclei

et al. 2018

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“…The GDR cross sections and GDR width for the nucleus 152 Gd are reported in Ref. [17] for the beam energy, E ∼ 149 MeV and later compiled along with the data at E ∼ 185 MeV in the Ref. [23].…”

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confidence: 99%

“…The results of these phenomenological formulae are similar to those of the TSFM in some cases. Despite a number of experiments been carried out to understand the properties of GDR and the effect of T and I on GDR [17][18][19], still there are several open questions. By large, the measured Γ are well interpreted by TSFM calculations, and the phenomenological scaling formula (PSF) [15] description also was successful in many cases.…”

Section: Introductionmentioning

confidence: 99%

Thermal shape fluctuation model study of the giant dipole resonance in $^{152}$Gd

Kumar,

Arumugam

2015

Preprint

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We have studied the giant dipole resonance (GDR) in the hot and rotating nucleus 152 Gd within the framework of thermal shape fluctuation model (TSFM) built on the microscopic-macroscopic calculations of the free energies with a macroscopic approach for the GDR. Our results for GDR cross sections are in good agreement with the experimental values except for a component peaking around 17 MeV where the data has large uncertainties. Such a component is beyond our description which properly takes care of the splitting of GDR components due to the deformation and Coriolis effects. Around this 17 MeV lies the half maximum in experimental cross sections, and hence the extracted GDR widths and deformations (estimated from these widths) turn out to be overestimated and less reliable. Reproducing these widths with empirical formulae could conceal the information contained in the cross sections. Fully microscopic GDR calculations and a more careful look at the data could be useful to understand the GDR component around 17 MeV. We also discuss the occurrence of γ-softness in the free energy surfaces of 152 Gd and its role on GDR.

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“…are found to be dependent on the temperature (T ) and angular momentum (J). Using high efficiency detector array setup, a few experiments [3,4] have been carried exclusively to study the dependence of temperature and angular momentum on GDR observables. Heavy ion fusion reactions impart a large amount of energy and angular momentum to the internal degrees of freedom in hot rotating nuclei.…”

Section: Introductionmentioning

confidence: 99%

Giant Dipole Resonance in A ~ 144 mass region

Mukul

Sugathan

Mazumdar

et al. 2013

EPJ Web of Conferences

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Abstract. Exclusive measurement of giant dipole resonance (GDR) γ rays has been performed in 144 Sm nucleus which was populated at near barrier energy using the heavy ion reaction of 28 Si beam on 116 Cd target. GDR γ rays were detected in coincidence with low energy γ rays using 32 elements 4π sum-spin spectrometer. The 144 Sm nucleus was populated at an excitation energy of 68 MeV in the temperature range of 1.1-1.3 MeV. The measured GDR widths in this temperature range are consistent with the Kusnezov's parametrization.

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Angular momentum dependence of the giant dipole resonance width in excited nuclei of mass

Cited by 11 publications

References 26 publications

Study of the Jacobi shape transition in A≈30 nuclei

Study of the Jacobi shape transition in A≈30 nuclei

Thermal shape fluctuation model study of the giant dipole resonance in $^{152}$Gd

Giant Dipole Resonance in A ~ 144 mass region

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