Multi-modal fission in collinear ternary cluster decay of 252 Cf(sf, fff)

Oertzen, W. von; Nasirov, A. K.; Tashkhodjaev, R. B.

doi:10.1016/j.physletb.2015.05.002

Cited by 21 publications

(12 citation statements)

References 35 publications

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“…The results are divided into four subsections. The first subsection covers final kinetic energies in the sequential decay model, both if the ternary particle is formed at the center (which is considered the most favorable case according to potential energy surface calculations [29,40,41]), and if the light fragment is formed at the center, for sake of completeness. The first subsection also includes a benchmark of the semi-classical trajectory calculations, which is used in the other models.…”

Section: Resultsmentioning

confidence: 99%

Collinear cluster tri-partition: Kinematics constraints and stability of collinearity

et al. 2017

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Background: A new mode of nuclear fission has been proposed by the FOBOS collaboration, called Collinear Cluster Tri-partition (CCT), suggesting that three heavy fission fragments can be emitted perfectly collinearly in low-energy fission. This claim is based on indirect observations via missing-energy events using the 2v2E method. This proposed CCT seems to be an extraordinary new aspect of nuclear fission. It is surprising that CCT escaped observation for so long given the relatively high reported yield, of roughly 0.5% relative to binary fission. These claims call for an independent verification with a different experimental technique.Purpose: Verification experiments based on direct observation of CCT fragments with fission fragment spectrometers require guidance with respect to the allowed kinetic energy range, which we present in this paper. Furthermore, we discuss corresponding model calculations which, if CCT is found in such verification experiments, could indicate how the breakups proceed. Since CCT refers to collinear emission, we also study the intrinsic stability of collinearity.Methods: Three different decay models are used that together span the timescales of three-body fission. These models are used to calculate the possible kinetic energy ranges of CCT fragments by varying fragment mass splits, excitation energies, neutron multiplicities and scission-point configurations. Calculations are presented for the systems 235 U(n th , f) and 252 Cf(sf), and the fission fragments previously reported for CCT, namely isotopes of the elements Ni, Si, Ca and Sn. In addition, we use semi-classical trajectory calculations with a Monte-Carlo method to study the intrinsic stability of collinearity.Results: CCT has a high net Q-value, but in a sequential decay, the intermediate steps are energetically and geometrically unfavorable or even forbidden. Moreover, perfect collinearity is extremely unstable, and broken by the slightest perturbation.Conclusions: According to our results, the central fragment would be very difficult to detect due to its low kinetic energy, raising the question of why other 2v2E experiments could not detect a missingmass signature corresponding to CCT. Considering the high kinetic energies of the outer fragments reported in our study, direct-observation experiments should be able to observe CCT. Furthermore, we find that a realization of CCT would require an unphysical fine-tuning of the initial conditions. Finally, our stability calculations indicate that, due to the pronounced instability of the collinear configuration, a prolate scission configuration does not necessarily lead to collinear emission, nor does equatorial emission necessarily imply an oblate scission configuration. In conclusion, our results enable independent experimental verification and encourage further critical theoretical studies of CCT.

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Section: Resultsmentioning

confidence: 99%

Collinear cluster tri-partition: Kinematics constraints and stability of collinearity

et al. 2017

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“…Moreover some theoretical works dedicated to this kind of ternary fission have been published [8][9][10][11][12][13][14][15][16]. In the Ref.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the tri-nuclear system at spontaneous fission of Cf252

2016

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To describe of dynamics of ternary fission of 252 Cf an equation of motion of the tri-nuclear system is calculated. The fission of the 70 Ni+ 50 Ca+ 132 Sn channel was chosen as one of the more probable channels of true ternary fission of 252 Cf. The collinearity of ternary fission has been checked by analyzing results of the equation of motion. The results show that if initially all nuclei are placed collinearly (potential energy of this position is the smallest) and the component of the middle fragment's initial velocity which is perpendicular to this line, is zero then ternary fission is collinear, otherwise the non collinear ternary fission takes place.

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“…The results demonstrating a crucial role of shell effects in the formation of the multibody chain-like nuclear molecules were obtained by Poenaru et al [39]. We also would like to refer to the recent theoretical articles devoted to unusual ternary decays of heavy nuclei including CCT [40][41][42][43][44][45][46].The authors analyze the potential energy of different pre-scission configurations leading to ternary decays, and the kinetic energies of the CCT partners [47] are calculated for a sequential decay process. These results can be considered as the first step in the description of the CCT process.…”

Section: Collinear Cluster Tri-partitionmentioning

confidence: 85%