Experimental determination of the fusion-barrier distribution for the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Sm</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>154</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mo>+</mml:mo></mml:mrow><mml:mr

Jiang, Wei; Leigh, J.R.; Hinde, David; Newton, J.O.; Lemmon, R. C.; Elfström, S.; Chen, J. X.; Rowley, N.

doi:10.1103/physrevlett.67.3368

Cited by 151 publications

(214 citation statements)

References 13 publications

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“…There are pronounced differences between this distribution and that of 16 O+ 154 Sm (Wei et al, 1991), which are just those expected from a change in sign of the hexadecapole deformation. These data hence demonstrate s strong sensitivity of fusion to the hexadecapole deformation.…”

Section: G Probing Shape Phase Transitions With Fusionmentioning

confidence: 63%

“…Such high-quality data recently became available for a number of systems. As a specific example of the quality of recent data, Figure 5 shows the measured cross section and the extracted associated barrier distribution for the 16 O + 154 Sm system (Wei et al, 1991;Leigh et al, 1995).…”

Section: Barrier Distributionsmentioning

confidence: 99%

“…Fusion cross sections for the reactions 16 O + 144,148,154 Sm and 16 O + 186 W were measured by the Australian National University group (Wei et al, 1991;Leigh et al, 1993;Lemmon et al, 1993;Morton et al, 1994;Leigh et al, 1995). The angular momentum distributions for 16 O + 154 Sm was measured by Bierman et al (1993), and for 16 O + 152 Sm by Wuosmaa et al (1991).…”

Section: B Higher-order Couplingsmentioning

confidence: 99%

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Quantum tunneling in nuclear fusion

1998

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Recent theoretical advances in the study of heavy ion fusion reactions below the Coulomb barrier are reviewed. Particular emphasis is given to new ways of analyzing data, such as studying barrier distributions; new approaches to channel coupling, such as the path integral and Green function formalisms; and alternative methods to describe nuclear structure effects, such as those using the Interacting Boson Model. The roles of nucleon transfer, asymmetry effects, higher-order couplings, and shape-phase transitions are elucidated. The current status of the fusion of unstable nuclei and very massive systems are briefly discussed.

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Section: G Probing Shape Phase Transitions With Fusionmentioning

confidence: 63%

Section: Barrier Distributionsmentioning

confidence: 99%

Section: B Higher-order Couplingsmentioning

confidence: 99%

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Quantum tunneling in nuclear fusion

1998

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“…In [6][7][8][9][10], fusion excitation functions were measured for 16 O (spherical) + 144−154 Sm reactions. 144 Sm is spherical whereas 154 Sm is prolate (β 2 ≈ 0.3).…”

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confidence: 99%

Quantum Calculations of Coulomb Reorientation for Sub-Barrier Fusion

2004

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Classical mechanics and Time Dependent Hartree-Fock (TDHF) calculations of heavy ions collisions are performed to study the rotation of a deformed nucleus in the Coulomb field of its partner. This reorientation is shown to be independent on charges and relative energy of the partners. It only depends upon the deformations and inertias. TDHF calculations predict an increase by 30% of the induced rotation due to quantum effects while the nuclear contribution seems negligible. This reorientation modifies strongly the fusion cross-section around the barrier for light deformed nuclei on heavy collision partners. For such nuclei a hindrance of the sub-barrier fusion is predicted.Tunneling, the slow "quantum leak" through a classical barrier, is an intriguing phenomenon in nature. In 1928, Gamow discovered this effect looking for an explanation of the α radioactivity [1]. However, the tunneling of complex systems remains to be understood. As in the Gamow times nuclear physics is providing one of the most challenging field to understand tunneling. In particular, fusion cross sections involving massive nuclei around the Coulomb barrier can be orders of magnitude over one dimensional quantum tunneling predictions. Couplings between the internal degrees of freedom and the relative motion deeply modifies tunneling [2]. Neutron transfer, excitation of low-lying vibrational and rotational states, neck formation, zero-point motion and polarization of collective surface vibration as well as static deformation have been identified as key inputs in the understanding of this sub-barrier fusion enhancement [3].For nuclei with a significant static quadrupole deformation [4,5], the main effects are i) on the barrier height (geometrical effect) since it is lower in the elongated direction and ii) on the reorientation of the deformed nucleus (rotational effect) under the torque produced by the long-range Coulomb force. In [6][7][8][9][10], fusion excitation functions were measured for 16 O (spherical) + 144−154 Sm reactions. 144 Sm is spherical whereas 154 Sm is prolate (β 2 ≈ 0.3). The data near the barrier were interpreted as arising from the different orientations of the prolate nucleus. An enhancement of the fusion probability is observed when the deformation axis is parallel to the collision axis ("parallel collision") and a hindrance when the two axis are nearly perpendicular ("perpendicular collision"). In these studies, however, the assumption of an isotropic orientation distribution of the deformed nucleus at contact was made. This contradicts classical calculations [11,12] which show partial reorientation. From the quantum mechanics point of view, the reorientation is a consequence of the excitation of rotational states, which may affect near barrier fusion specially for light deformed nuclei [13,14]. Computational techniques have been developed in the past to solve coupled channel (CC) equations for Coulomb excitation [15-18] but a good understanding of the Coulomb reorientation dynamics during the approach phase is still re...

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“…It was at one of these meetings, the 1991 Daresbury Workshop on Heavy-ion Collisions, where the concept of extracting experimental distribution of fusion barriers [1] was proposed by Rowley et al Later that year, the high precision measurements made by the group led by Jack Leigh at the Australian National University made it an experimental reality [2]. The strength of the concept is that it allows a very sensitive measure of couplings and hence after all these years still serves a critical test of models.…”

mentioning

confidence: 99%