Exclusive giant dipole resonance measurement on the Jacobi transition in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>19</mml:mn></mml:msup></mml:math>F+<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>27</mml:mn></mml:msup></mml:math>Al system

Chakrabarty, D. R.; Datar, V. M.; Kumar, Suresh; Mishra, Gauravi; Mirgule, E. T.; Mitra, A.; Rout, P. C.; Nanal, V.; Pandit, Deepak; Mukhopadhyay, S.; Bhattacharya, Srijit

doi:10.1103/physrevc.85.044619

Cited by 11 publications

(6 citation statements)

References 13 publications

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“…One can conjecture that the origin of the high energy component (∼ 25 MeV) is due to the emission of highenergy γ-rays from much lighter compound nuclei formed by incomplete fusion. However, in our earlier work on evaporation-residue-gated Jacobi shape transition [30], it was observed that the non-fusion events were accompanied by γ-rays in the range of 5-10 MeV and were associated with low angular momentum events only. Since our measurement was biased towards the higher multiplicity events, it can be inferred that the γ-rays are emitted from a fully energy equilibrated composite.…”

Section: Resultsmentioning

confidence: 93%

“…In general, the light nuclei are expected to undergo Jacobi shape transition, an abrupt change of shape from a non-collective oblate to a collectively rotating prolate or triaxial shape, at high angular momentum (J ∼ 17h for 32 S). Experimentally, it is observed as a sharp low energy component (∼ 10 MeV) in the GDR spectrum [22,30,32]. This peak arises due to the Coriolis splitting of the GDR frequency corresponding to the largest axis of a collectively rotating prolate when the frequencies are transformed from internal rotating coordinate frame to the laboratory frame [33].…”

Section: Resultsmentioning

confidence: 97%

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Signature of clustering in quantum many-body systems probed by the giant dipole resonance

et al. 2017

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The present experimental study illustrates how large deformations attained by nuclei due to cluster formation are perceived through the giant dipole resonance (GDR) strength function. The high energy GDR γ-rays have been measured from 32 S at different angular momenta (J) but similar temperatures in the reactions 4 He(E lab =45MeV) + 28 Si and 20 Ne(E lab =145MeV) + 12 C. The experimental data at lower J (∼ 10h) suggests a normal deformation, similar to the ground state value, showing no potential signature of clustering. However, it is found that the GDR lineshape is fragmented into two prominent peaks at high J (∼ 20h) providing a direct measurement of the large deformation developed in the nucleus. The observed lineshape is also completely different from the ones seen for Jacobi shape transition at high J pointing towards the formation of cluster structure in super-deformed states of 32 S at such high spin. Thus, the GDR can be regarded as a unique tool to study cluster formation at high excitation energies and angular momenta.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 97%

Signature of clustering in quantum many-body systems probed by the giant dipole resonance

et al. 2017

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“…In addition, for other topics addressed via the GDR in hot nuclei such as fission, isospin symmetry and Jacobi transitions the reader could refer to Refs. [11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

The hot GDR revisited

Santonocito

Blumenfeld

2020

Eur. Phys. J. A

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The properties of the Isovector Giant Dipole Resonance are reviewed as a function of the temperature of the state on which it is built. The experimental methods, based on scintillation detectors efficient for the detection of high energy gamma-rays, are described. Methods for determining the excitation energy and temperature from the measurement of light charged particle energy spectra taking pre-equilibrium emission into account are presented. The resonance properties, energy, width and strength, are followed as a function of increasing temperature. The data are analyzed in the framework of the statistical model, which is briefly presented, by using the codes CASCADE and DCASCADE. Various prescriptions for the characteristics of the resonance as well as theoretical models are incorporated into these statistical codes in view of a direct comparison with the data. The successes and deficiencies of the Thermal Shape Fluctuation model at low temperatures are discussed. A salient feature is the surprisingly abrupt disappearance of dipole strength above a limiting temperature which depends on the nuclear mass. Several models taking into account the competition between the time scales of collective degrees of freedom and nuclear lifetime only roughly reproduce the trend of the data. This disappearance of strength is tentatively linked to the nuclear liquid–gas phase transition.

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“…Most noteworthy is the large yield in both neutron energy spectrum (beyond 6 MeV) and GDR γ ray (around 16 MeV) spectrum. This high energy GDR γ ray at 16 MeV can only arise from fully energy equilibrated compound nucleus since the nonfusion events are accompanied by γ rays less than 10 MeV [39]. It is also interesting to note that the GDR and the neutron decay explore the same excitation energy region in the daughter nuclei 169 Tm and 168 Tm, respectively.…”

Section: Neutron Detectormentioning

confidence: 87%

Experimental signature of collective enhancement in nuclear level density

Pandit

Bhattacharya²,

Mondal

et al. 2018

Phys. Rev. C

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We present a probable experimental signature of collective enhancement in the nuclear level density (NLD) by measuring the neutron and the giant dipole resonance (GDR) γ rays emitted from the rare earth 169 Tm compound nucleus populated at 26.1 MeV excitation energy. An enhanced yield is observed in both neutron and γ ray spectra corresponding to the same excitation energy in the daughter nuclei. The enhancement could only be reproduced by including a collective enhancement factor in the Fermi gas model of NLD to explain the neutron and GDR spectra simultaneously. The experimental results show that the relative enhancement factor is of the order of 10 and the fadeout occurs at ∼ 14 MeV excitation energy, much before the commonly accepted transition from deformed to spherical shape. We also explain how the collective enhancement contribution changes the inverse level density parameter (k) from 8 to 9.5 MeV observed recently in several deformed nuclei.

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Exclusive giant dipole resonance measurement on the Jacobi transition in the19F+27Al system

Cited by 11 publications

References 13 publications

Signature of clustering in quantum many-body systems probed by the giant dipole resonance

Signature of clustering in quantum many-body systems probed by the giant dipole resonance

The hot GDR revisited

Experimental signature of collective enhancement in nuclear level density

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