Direct observation of first-chance fission of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">No</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>258</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>

Peterson, D.; Loveland, W.; Batenkov, O. I.; Majorov, M.; Veshikov, A.; Aleklett, K.; Rouki, C.

doi:10.1103/physrevc.79.044607

Cited by 20 publications

(7 citation statements)

References 41 publications

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“…The nature and magnitude of nuclear dissipation has been investigated extensively, both experimentally and theoretically, in recent years [1][2][3][4][5][6][7][8][9][10]. Because of dissipation, fission is delayed.…”

mentioning

confidence: 99%

Isospin effects on light charged particles as probes of nuclear dissipation

2009

Phys. Rev. C

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The multiplicities of postsaddle protons and α particles of the heavy systems 234 Cf, 240 Cf, 246 Cf, and 240 U as functions of the postsaddle dissipation strength are calculated in the framework of a dynamical Langevin model coupled with a statistical decay model. It is found that with increasing isospin of the Cf system, the sensitivity of the postsaddle proton and α-particle multiplicity to the dissipation strength decreases substantially, and it disappears for the 240 U system. We suggest that on the experimental side, to accurately probe the postsaddle dissipation strength by measuring the prescission proton and α-particle multiplicity, it is best to populate heavy compound systems with low isospin.

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mentioning

confidence: 99%

Isospin effects on light charged particles as probes of nuclear dissipation

2009

Phys. Rev. C

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“…This suggests that slow quasifission dynamics occurs here without any loss of energy due to neutron evaporation, and therefore occurs at the initial excitation energy of the system, in a similar way to first-chance fission. In contrast, for fusion-fission it is known that multichance fission is significant [8,[30][31][32][33][34]. This means that fusion-fission also occurs after emission of one or more neutrons, and this can be a major contributor to the total FMT fission yield.…”

Section: Fig 13 Fmt Fission Angular Anisotropies (A) Plotted As a Fmentioning

confidence: 99%

Systematic evidence for quasifission in Be9−, C12−, and
Banerjee
¹
,
Hinde
²
,
Jeung
³

et al. 2020
Phys. Rev. C
13
0
2
0
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Background: Cross sections for the formation of superheavy elements (SHE) by heavy ion fusion are suppressed by the competing quasifission process. This results in a fissionlike decay after capture but before formation of a compact compound nucleus. Fast quasifission is evident from very mass-asymmetric fission, focused in angle. In contrast, slow quasifission shows no significant mass-angle correlation, and a mass distribution peaked at symmetry. However, it shows angular distributions more anisotropic than those calculated for fission following fusion. Following fusion, low excitation energies should increase SHE survival through reduced competition from fission. However, in reactions with deformed actinide target nuclei, subbarrier fusion is highly suppressed by both fast and slow quasifission. Purpose: To investigate the threshold for quasifission by investigating signatures of slow quasifission in both fission angular and mass distributions, as a function of beam energy with respect to the capture barrier, for the projectiles 9 Be, 12 C, and 16 O that form the neighboring compound nuclei 258,260 No. Methods: Fission mass and angular distributions have been measured from below to above-barrier energies using the kinematic coincidence method for the reactions 9 Be + 249 Cf, 12 C + 248 Cm, and 16 O + 244 Pu. Fission following transfer reactions can significantly contaminate fission events that follow capture, and must be rejected. Existing methods to reject transfer-induced fission have been refined to allow quantitative subtraction of the transfer fission component. Results: The capture-fission mass-angle distributions show no evidence for fast quasifission, as might be expected. However, measured fission fragment angular anisotropies are larger than transition state model (TSM) calculations for fusion fission. The deviations increase with larger projectile charge and for bombarding energies below the mean capture barrier energy. Even for the 9 Be + 249 Cf reaction, the subbarrier angular anisotropy significantly exceeds the TSM calculation. Fission mass distributions measured at the same excitation energies also show a consistent dependence on the projectile charge. Conclusions: New refined analysis techniques have been developed to enable reliable separation of fission following capture from sequential fission following transfer reactions. For fission following capture at abovebarrier energies, the 9 Be angular anisotropies are close to the TSM predictions, supporting the validity of TSM calculations of fusion-fission for such heavy elements. At subbarrier energies the angular anisotropy data indicate a component of slow quasifission even for 9 Be, and a probability that increases rapidly with projectile charge. It is concluded that the probability of slow quasifission changes smoothly with projectile charge, having no sharp threshold.

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“…Experimentally, the measurement of survival probabilities is feasible. For example, very large survival probabilities of 258 No [8] and 274 Hs [9] have been directly obtained in hot fusion reactions, which provide a good opportunity to verify various theoretical models.…”

Section: Cn Surmentioning

confidence: 99%

Towards microscopic studies of survival probabilities of compound superheavy nuclei

Zhu¹,

Pei

2017

Phys. Scr.

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Abstract. The microscopic approach of fission rates and neutron emission rates in compound nuclei have been applied to 258 No and 286 Cn. The microscopic framework is based on the finite-temperature Skyrme-Hartree-Fock+BCS calculations, in which the fission barriers and mass parameters are self-consistently temperature dependent. The fission rates from low to high temperatures can be obtained based on the imaginary free energy method. The neutron emission rates are obtained with neutron gases at surfaces. Finally the survival probabilities of superheavy nuclei can be calculated microscopically. The microscopic approach has been compared with the widely used statistical models. Generally, there are still large uncertainties in descriptions of fission rates.

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Direct observation of first-chance fission ofNo258

Cited by 20 publications

References 41 publications

Isospin effects on light charged particles as probes of nuclear dissipation

Isospin effects on light charged particles as probes of nuclear dissipation

Systematic evidence for quasifission in Be9−, C12−, and
Banerjee
¹
,
Hinde
²
,
Jeung
³

et al. 2020
Phys. Rev. C
13
0
2
0
View full text Add to dashboard Cite

Towards microscopic studies of survival probabilities of compound superheavy nuclei

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Direct observation of first-chance fission ofNo258

Cited by 20 publications

References 41 publications

Isospin effects on light charged particles as probes of nuclear dissipation

Isospin effects on light charged particles as probes of nuclear dissipation

Systematic evidence for quasifission in Be9−, C12−, and Banerjee1, Hinde2, Jeung3 et al. 2020Phys. Rev. C13020View full textAdd to dashboardCite

Towards microscopic studies of survival probabilities of compound superheavy nuclei

Contact Info

Product

Resources

About

Systematic evidence for quasifission in Be9−, C12−, and
Banerjee
¹
,
Hinde
²
,
Jeung
³

et al. 2020
Phys. Rev. C
13
0
2
0
View full text Add to dashboard Cite