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Thomas, R. G.; Hinde, David; Duniec, D.; Zenke, F.; Dasgupta, M.; Brown, Michael L.; Evers, M.; Gasques, L. R.; Rodríguez, Matías; Díaz-Torres, A.

doi:10.1103/physrevc.77.034610

Cited by 89 publications

(62 citation statements)

References 35 publications

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“…To define the smooth trends in quasifission, a large number of MAD measurements have been selected from measurements recently made at the ANU [3][4][5][11][12][13][14][15][16][17]. By investigating empirically those nuclear stucture variables that affect quasifission, the ultimate goal to have a reliable predictive model of quasifission, including all relevant physics, will be a step closer.…”

Section: Mass-angle Distributionsmentioning

confidence: 99%

Nuclear structure effects in quasifission – understanding the formation of the heaviest elements

et al. 2016

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Abstract. Quasifission is an important process suppressing the fusion of two heavy nuclei in reactions used to create superheavy elements. Quasifission results in rapid separation of the dinuclear system initially formed at contact. Achieving reliable a priori prediction of quasifission probabilities is a very difficult problem. Through measurements with projectiles from C to Ni, the Australian National University's Heavy Ion Accelerator Facility and CUBE spectrometer have been used to map out mass-angle distributions (MAD) -the fission mass-ratio as a function of centre-of-mass angle. These provide information on quasifission dynamics in the least modeldependent way. Average quasifission time-scales have been extracted, and compared with TDHF calculations of the collisions, with good agreement being found. With the baseline information from the survey of experimental MAD, strong influences of the nuclear structure of the projectile and target nuclei can be clearly determined.

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Section: Mass-angle Distributionsmentioning

confidence: 99%

Nuclear structure effects in quasifission – understanding the formation of the heaviest elements

et al. 2016

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“…Quasifission mass-angle distributions (MAD) first measured at GSI in the 1980s [2,5] showed that quasifission timescales could often be shorter than the rotation time of ∼10 −20 s. However, subsequently only a few measurements [6,7] were made until recent years, when an extensive series of experiments (using the Australian National University Heavy Ion Accelerator Facility and CUBE spectrometer) were carried out [3,[8][9][10][11][12][13][14][15][16]. The kinematic coincidence technique used in the measurements [2,3,17] provides direct information on the mass-ratio of the fragments at scission; thus, the data are represented in terms of mass ratio M R , rather than pre-or According to the characteristics of the MAD (minimum mass yield at symmetry, mass-angle correlation with peak yield at symmetry, and no significant mass-angle correlation), they are assigned as type MAD1, MAD2 and MAD3 respectively [3].…”

Section: Introductionmentioning

confidence: 99%

Systematic study of quasifission characteristics and timescales in heavy element formation reactions

Hinde

Williams

Mohanto

et al. 2016

EPJ Web of Conferences

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Superheavy elements can only be created in the laboratory by the fusion of two massive nuclei. Mass-angle distributions give the most direct information on the characteristics and time scales of quasifission, the major competitor to fusion in these reactions. The systematics of 42 mass-angle distributions provide information on the global characteristics of quasifission. Deviations from the systematics reveal the major role played by the nuclear structure of the two colliding nuclei in determining the reaction outcome, and in hindering or favouring heavy element production.To form very heavy and superheavy elements (SHE), heavy-ion fusion reactions are used. Their cross sections can be significantly suppressed [1] by quasifission [2]. This dynamical non-equilibrium process results when the combined system formed after capture separates into two (fission-like) fragments in times ∼10 −20 s, before a compact compound nucleus is formed. The probability of quasifission (P QF ) can be very large, with the corresponding probability of compound nucleus formation (P CN = 1 -P QF ) being lower than 10 −3 in unfavourable cases. Understanding the competition between quasifission and fusion is thus very important in predicting the best fusion reactions to use to form new isotopes of heavy and super-heavy elements.A key quantity characterizing quasifission is its "sticking time" between capture of the two nuclei inside the entrance channel potential barrier [4] and breakup (scission). Quasifission mass-angle distributions (MAD) first measured at GSI in the 1980s [2,5] showed that quasifission timescales could often be shorter than the rotation time of ∼10 −20 s. However, subsequently only a few measurements [6,7] were made until recent years, when an extensive series of experiments (using the Australian National University Heavy Ion Accelerator Facility and CUBE spectrometer) were carried out [3,[8][9][10][11][12][13][14][15][16]. The kinematic coincidence technique used in the measurements [2,3,17] provides direct information on the mass-ratio of the fragments at scission; thus, the data are represented in terms of mass ratio M R , rather than pre-or According to the characteristics of the MAD (minimum mass yield at symmetry, mass-angle correlation with peak yield at symmetry, and no significant mass-angle correlation), they are assigned as type MAD1, MAD2 and MAD3 respectively [3]. There is a clear correlation between the MAD class and the entrance channel charge product. Other entrance channel characteristics are important in determining the sticking times and MAD characteristics, including neutron richness [14,18], and shell structure including static deformation [11] and magic numbers [14].To improve our quantitative understanding of the role of shell structure in the dynamics of quasifission, we make an analogy with the liquid drop model approach to nuclear masses, in which localized shell effects can be quantified when the underlying smooth (liquid drop) trends are well defined. To define the smooth trends in ...

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“…Usual experimental observables to investigate the quasifission process include, in addition to the fragment mass distribution, the kinetic energy of the fragments [13] and the scattering angle [6,51]. Figure 10 shows the evolution of the scattering angle in 40 Ca+ 238 U at E c.m.…”

Section: Quasi-fission Within the Tdhf Approachmentioning

confidence: 99%

Effects of nuclear structure on quasi-fission

Simenel

Wakhle

Avez

et al. 2012

EPJ Web of Conferences

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Abstract. The quasi-fission mechanism hinders fusion of heavy systems because of a mass flow between the reactants, leading to a re-separation of more symmetric fragments in the exit channel. A good understanding of the competition between fusion and quasi-fission mechanisms is expected to be of great help to optimize the formation and study of heavy and superheavy nuclei. Quantum microscopic models, such as the time-dependent Hartree-Fock approach, allow for a treatment of all degrees of freedom associated to the dynamics of each nucleon. This provides a description of the complex reaction mechanisms, such as quasi-fission, with no parameter adjusted on reaction mechanisms. In particular, the role of the deformation and orientation of a heavy target, as well as the entrance channel magicity and isospin are investigated with theoretical and experimental approaches.

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Entrance channel dependence of quasifission in reactions formingTh220

Cited by 89 publications

References 35 publications

Nuclear structure effects in quasifission – understanding the formation of the heaviest elements

Nuclear structure effects in quasifission – understanding the formation of the heaviest elements

Systematic study of quasifission characteristics and timescales in heavy element formation reactions

Effects of nuclear structure on quasi-fission

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