Non-compound-nucleus fission events and standard saddle-point statistical model

Soheyli, S.; Khalili, Morteza Khalil

doi:10.1103/physrevc.85.034610

Cited by 12 publications

(4 citation statements)

References 53 publications

(82 reference statements)

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“…A memory of the entrance channel effects, such as the Coulomb interaction parameter (z), compound nucleus (CN) fissility (χ CN ), effective entrance channel fissility (χ eff ), mean fissility (χ m ), charge (α) and mass asymmetry (η), is often retained in the heavy-ion reactions [10][11][12][13][14], especially, producing CN of A ≈ 220 [15], A ≈ 230 [16], actinide [17] and the superheavy regime [18]. The entrance channel dynamics for cold fusion reactions were studied in detail about two decades ago [19].…”

Section: Introductionmentioning

confidence: 99%

Rules of thumb for synthesizing superheavy elements

Manjunatha¹,

Vidya²,

Gupta³

et al. 2022

J. Phys. G: Nucl. Part. Phys.

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Synthesizing any elements in the eighth period using either cold or hot fusion reactions remains a big challenge till date. Quasifission mechanism restricts complete fusion to an indeterminably low evaporation residue (ER) cross section for the superheavy nuclei. Entrance channel parameters of the heavy-ion reaction, fission barrier of compound nucleus, deformation parameters of the projectile and target nuclei, and the kinetic energy of the projectile are mostly responsible in governing the scales of the quasifission. Role of these factors has been examined explicitly by the experimental ER cross sections. Thorough comparisons lead us to infer that the entrance channel criteria contribute much lower extent than the deformation parameters do. The effect of deformation can be categorized into four rules as validated by all the reactions used except one $^{45}_{21}$Sc+$^{249}_{98}$Cf $\rightarrow ^{294}_{119}$Uue. Null result from this reaction is well explained by an improper choice of the projectile energy as shown theoretically by means of a statistical model approach, which is valid for a system having a large nucleon number so as to have intrinsically a high density of excited states. Optimal selection of the beam energy sets another rule. Therefore, these five rules can be treated as the rules of thumb for synthesizing the superheavy elements. Application of the first four rules can enable us to spot primarily a suitable reaction and finally exploitation of the fifth rule chooses the most appropriate reaction at a preferable excited energy to achieve the highest ER cross section for a superheavy element.

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Section: Introductionmentioning

confidence: 99%

Rules of thumb for synthesizing superheavy elements

Manjunatha¹,

Vidya²,

Gupta³

et al. 2022

J. Phys. G: Nucl. Part. Phys.

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“…Fission fragment angular distributions can be calculated from analytical expressions based on the angular momentum state of the fissioning nucleus [6,7]. At high excitation energies, these discrete angular momentum states are expected to turn into a continuous regime [8,9]. Experimentally, a sum of different angular momentum states contributes to the measured angular distribution of fission fragments at each incident neutron energy.…”

Section: Introductionmentioning

confidence: 99%

Neutron Induced Fission Fragment Angular Distributions, Anisotropy, and Linear Momentum Transfer Measured with the NIFFTE Fission Time Projection Chamber

Hensle,

Barker,

Barrett

et al. 2020

Preprint

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The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has performed measurements with a fission time projection chamber (fissionTPC) to study the fission process by reconstructing full three-dimensional tracks of fission fragments and other ionizing radiation. The amount of linear momentum imparted to the fissioning nucleus by the incident neutron can be inferred by measuring the opening angle between the fission fragments. Using this measured linear momentum, fission fragment angular distributions can be converted to the center-of-mass frame for anisotropy measurements. Angular anisotropy is an important experimental observable for understanding the quantum mechanical state of the fissioning nucleus and vital to determining detection efficiency for cross section measurements. Neutron linear momentum transfer to fissioning 235 U, 238 U, and 239 Pu and fission fragment angular anisotropy of 235 U and 238 U as a function of neutron energies in the range 130 keV-250 MeV are presented.

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“…A memory of entrance channel effects such as the Coulomb interaction parameter (z), compound nucleus fissility (χ CN ), effective entrance channel fissility (χ ef f ), mean fissility (χ m ), charge (α Z ) and mass asymmetry (η A ) is often retained in the heavy-ion reactions [10,11], especially, producing compound nucleus (CN) of A≈ 220 [12], A≈ 230 [13], actinide [14] and superheavy elements [15]. The entrance channel dynamics for the cold fusion reactions have been studied in detail about two decades ago [16].…”

mentioning

confidence: 99%

Exploring an experimental route of synthesizing superheavy elements beyond Z > 118

Manjunatha,

Vidya,

Gupta

et al. 2021

Preprint

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Role of the Coulomb interaction, mean fissility, mass asymmetry, and charge asymmetry parameters on the synthesis of heavy and superheavy elements has been examined with respect to the deformation parameters of the projectile and target nuclei explicitly in light of the experimental results. The observed facts are classified into four categories and are then used to study several unsuccessful as well as planned reactions to synthesize the new superheavy elements Z = 119, 120. Concrete inference is too difficult to draw from these results because of excessive deviations in evaporation residue cross-section data. It is found that the arbitrary choice of excitation energy for the experiments studied was the root cause of such large deviations. Such a complex issue can be resolved well by theoretical excitation function studies using the advanced statistical model or the dinuclear system model and choosing the excitation energy corresponding to the energy where the excitation function curve shows the maximum. We believe this method may help us to predict whether the estimated evaporation residue cross section can be measurable within the experimental limit of the existing facilities for the future reactions planned.

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Non-compound-nucleus fission events and standard saddle-point statistical model

Cited by 12 publications

References 53 publications

Rules of thumb for synthesizing superheavy elements

Rules of thumb for synthesizing superheavy elements

Neutron Induced Fission Fragment Angular Distributions, Anisotropy, and Linear Momentum Transfer Measured with the NIFFTE Fission Time Projection Chamber

Exploring an experimental route of synthesizing superheavy elements beyond Z > 118

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