Fusion cross sections at deep sub-barrier energies

Hagino, K.; Rowley, N.; Dasgupta, M.

doi:10.1103/physrevc.67.054603

Cited by 91 publications

(87 citation statements)

References 22 publications

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“…It was observed that a wide range of values from 0.65 a fm  to fm a 5 . 1  of diffuseness parameter are required to describe various nuclear phenomena [5][6][7][8][9][10][11][12]. As the value of diffuseness parameter increases beyond 0.65 a fm  , the potential pocket becomes more and more shallow and disappears for large values and the fusion barrier radius decreases rapidly [6,[13][14][15].…”

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confidence: 99%

Relative importance of energy dependent diffuseness parameter and barrier position in the analysis of fusion excitation function data

Kharab

Singh

2014

EPJ Web of Conferences

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Abstract.We have investigated the relative importance of the energy dependence of diffuseness parameter and barrier position in the description of the fusion excitation function data of some heavy ion systems in near barrier energy region. The effects of the energy dependent diffuseness parameter are found to be much more prominent in comparison to those of barrier position.The sub-barrier heavy ion fusion reactions provide a very good insight into nuclear structure and nuclear interaction [1][2][3][4]. The interaction potential between heavy ions which consists of Coulomb, centrifugal and nuclear terms plays a very crucial role in the description of fusion dynamics because of the fact that the sum of these terms forms the Coulomb barrier which must be overcome for occurrence of fusion. The Coulomb and centrifugal terms are well understood whereas many ambiguities are associated with the nuclear potential. Since the predictions of fusion excitation functions in sub-barrier energy regions are very sensitive to the shape of nuclear potential, the success of any model for fusion depends strongly on the nuclear potential model employed in the analysis. As a result various potential models ranging from the simple phenomenological to realistic microscopic models have been proposed and used to explain the fusion excitation functions data. Generally, the three parametric Woods-Saxon potential remains the most frequently used potential for the description of compound nuclear reactions. Among the three parameters, depth, range and diffuseness parameter, there exist, large ambiguities in the determination of the accurate value of the diffuseness parameter. It was observed that a wide range of values from 0.65 a fm  to fm a 5 . 1  of diffuseness parameter are required to describe various nuclear phenomena [5][6][7][8][9][10][11][12]. As the value of diffuseness parameter increases beyond 0.65 a fm  , the potential pocket becomes more and more shallow and disappears for large values and the fusion barrier radius decreases rapidly [6,[13][14][15]. Very recently, an energy dependent parameterization scheme to determine the value of diffuseness parameter was successfully used to explain the fusion excitation functions of various systems [16]. Since, the barrier position changes with the change in the shape of the potential, the energy dependent potential induces energy dependence in the barrier position also. ____________________________________________ a Corresponding

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Relative importance of energy dependent diffuseness parameter and barrier position in the analysis of fusion excitation function data

Kharab

Singh

2014

EPJ Web of Conferences

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“…For instance, it has been a long-standing problem that a standard value of a ∼ 0.63 fm for the surface diffuseness parameter of the real nuclear potential appears too small to account for fusion data, even though this value is required to fit scattering data [12,13]. This problem is also related [14][15][16] to the deviations of fusion cross sections at deep subbarrier energies from the predictions of standard coupled-channels calculations [17][18][19][20].…”

Section: Introductionmentioning

confidence: 97%

Quasi-elastic scattering in the20Ne+90,92Zr reactions: Role of noncollective excitations

2013

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Conventional coupled-channels analyses, that take account of only the collective excitations of the colliding nuclei, have failed to reproduce the different behavior of the experimental quasi-elastic barrier distributions for the 20 Ne + 90,92 Zr systems. To clarify the origins of this difference, we investigate the effect of non-collective excitations of the Zr isotopes. Describing these excitations in a random-matrix model, we explicitly take them into account in our coupled-channels calculations. The non-collective excitations are capable of reproducing the observed smearing of the peak structure in the barrier distribution for 20 Ne + 92 Zr, while not significantly altering the structure observed in the 20 Ne + 90 Zr system. The difference is essentially related to the closed neutron shell in 90 Zr.

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“…The agreement between the calculation and the experimental data is reasonable both for the fusion and the quasi-elastic barrier distributions. For the fusion barrier distribution D fus , the agreement will be further improved if one uses a larger value of diffuseness parameter a [5,27] (see the dotted line). Fig.…”

Section: Barrier Distribution For Multi-channel Systemsmentioning

confidence: 99%

Large-angle scattering and quasielastic barrier distributions

2004

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We study in detail the barrier distributions extracted from large-angle quasi-elastic scattering of heavy ions at energies near the Coulomb barrier. Using a closed-form expression for scattering from a single barrier, we compare the quasi-elastic barrier distribution with the corresponding test function for fusion. We examine the isocentrifugal approximation in coupled-channels calculations of quasi-elastic scattering and find that for backward angles, it works well, justifying the concept of a barrier distribution for scattering processes. This method offers an interesting tool for investigating unstable nuclei. We illustrate this for the 32 Mg + 208 Pb reaction, where the quadrupole collectivity of the neutron-rich 32 Mg remains to be clarified experimentally.

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Fusion cross sections at deep sub-barrier energies

Cited by 91 publications

References 22 publications

Relative importance of energy dependent diffuseness parameter and barrier position in the analysis of fusion excitation function data

Relative importance of energy dependent diffuseness parameter and barrier position in the analysis of fusion excitation function data

Quasi-elastic scattering in the20Ne+90,92Zr reactions: Role of noncollective excitations

Large-angle scattering and quasielastic barrier distributions

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