Excitation energy dependence of fragment-mass distributions from fission of 180,190 Hg formed in fusion reactions of 36 Ar + 144,154 Sm

Nishio, K.; Andreyev, A. N.; Chapman, R.; Derkx, X.; Düllmann, Ch. E.; Ghys, L.; Heßberger, F. P.; Hirose, K.; Ikezoe, H.; Khuyagbaatar, J.; Kindler, B.; Lommel, B.; Makii, H.; Nishinaka, I.; Ohtsuki, T.; Pain, S. D.; Sagaidak, R. N.; Tsekhanovich, I.; Venhart, M.; Wakabayashi, Y.; Yan, S. Q.

doi:10.1016/j.physletb.2015.06.068

Cited by 54 publications

(41 citation statements)

References 32 publications

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“…Though both theoretical predictions and experimental results show similar trends in mass split, the mass centroids of the asymmetric peaks are different. Similar observations may also be made for the low energy [14] and high energy [10] fission of 180 Hg. However, the predicted results match with the experimental results for 190 Hg [10].…”

Section: Resultssupporting

confidence: 80%

“…Similar observations may also be made for the low energy [14] and high energy [10] fission of 180 Hg. However, the predicted results match with the experimental results for 190 Hg [10]. In addition to the mismatch in mass centroids, significant difference in the FWHM of the asymmetric peaks was observed in the experimental results and BSM predictions.…”

Section: Resultssupporting

confidence: 80%

“…While the fragments from 180,190 Hg showed signatures of asymmetric mass split, a symmetric distrbution is observed for the fission of 195 Hg. While the observation of mass-asymmetric fission superficially support the existence of shell effects even at high excitation energies as claimed in [10] and predicted in Refs. [19,20], we also show empirically that the results could be explained by using a 25% fission contribution from 180 Hg.…”

Section: Discussionsupporting

confidence: 72%

“…Such a flat-topped distribution has been represented by the sum of two Gaussian functions in Ref. [10] …”

Section: Resultsmentioning

confidence: 99%

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Mass-asymmetric fission in the⁴⁰ca+¹⁴²Nd reaction

et al. 2016

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Abstract. Shell effects play a major role in fission. Mass-asymmetric fission observed in the spontaneous and low energy fission of actinide nuclei was explained by incorporating the fragment shell properties in liquid drop model. Asymmetric fission has also been observed in the low energy fission of neutron-deficient 180 Hg nuclei in recent β-delayed fission experiments. This low-energy β-delayed fission has been explained in terms of strong shell effects in pre-scission configurations associated with the system after capture. Calculations predicted asymmetric fission for heavier Hg isotopes as well, at compound nuclear excitation energy as high as 40 MeV. To explore the evolution of fission fragment mass distribution as a function of neutron and proton numbers and also with excitation energy, fission fragment mass distributions have been measured for the 40 Ca+ 142 Nd reaction forming the compound nucleus 182 Hg at energies around the capture barrier, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Mass-asymmetric fission is observed in this reaction at an excitation energy of 33.6 MeV. The results are consistent with the β-delayed fission measurements and indicate the presence of shell effects even at higher exciation energies.

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Section: Resultssupporting

confidence: 80%

Section: Resultssupporting

confidence: 80%

Section: Discussionsupporting

confidence: 72%

“…Such a flat-topped distribution has been represented by the sum of two Gaussian functions in Ref. [10] …”

Section: Resultsmentioning

confidence: 99%

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Mass-asymmetric fission in the⁴⁰ca+¹⁴²Nd reaction

et al. 2016

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“…We now introduce a complementary method to investigate shell effects in the pre-fragments. Instead of constraining the shape of an isolated fragment, the singleparticle energies are studied in the entire fissioning nu- [20,22,73,74]. Isodensities surface at half the saturation density ρ0/2 = 0.08 fm −3 at scission associated with each inset are shown for each asymmetric fission mode with the heavy fragment on the right.…”

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confidence: 99%

Effect of shell structure on the fission of sub-lead nuclei

Scamps

Simenel

2019

Phys. Rev. C

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Fission of atomic nuclei often produce mass asymmetric fragments. However, the origin of this asymmetry was believed to be different in actinides and in the sub-lead region [A. Andreyev et al., Phys. Rev. Lett. 105, 252502 (2010)]. It has recently been argued that quantum shell effects stabilising pear shapes of the fission fragments could explain the observed asymmetries in fission of actinides [G. Scamps and C. Simenel, Nature 564, 382 (2018)]. This interpretation is tested in the sub-lead region using microscopic mean-field calculations of fission based on the Hartree-Fock approach with BCS pairing correlations. The evolution of the number of protons and neutrons in asymmetric fragments of mercury isotope fissions is interpreted in terms of deformed shell gaps in the fragments. A new method is proposed to investigate the dominant shell effects in the pre-fragments at scission. We conclude that the mechanisms responsible for asymmetric fissions in the sub-lead region are the same as in the actinide region, which is a strong indication of their universality.

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