Theoretical study of the almost sequential mechanism of true ternary fission

Tashkhodjaev, R. B.; Muminov, A. I.; Nasirov, A. K.; Oertzen, W. von; Oh, Yongseok

doi:10.1103/physrevc.91.054612

Cited by 23 publications

(27 citation statements)

References 23 publications

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“…The PES's are calculated, more details are given in Refs. [27,35], using the binding energies of the three fragments, B 1 , B 2 , B 3 and of the fissioning nucleus B CN . With the ternary Q -value, Q ggg = B 1 + B 2 + B 3 − B CN and the sum of interactions (nuclear and Coulomb) between all three fragments, the PES is obtained.…”

Section: Potential Energy Surface (Pes) Internal Barriers In Ternarymentioning

confidence: 99%

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

2015

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We discuss the multiple decay modes of collinear fission in 252 Cf(sf, fff), with three fragments as suggested by the potential energy surface (PES). Fission as a statistical decay is governed by the phase space of the different decay channels, which are suggested in the PES-landscape. The population of the fission modes is determined by the minima in the PES at the scission points and on the internal potential barriers. The ternary collinear decay proceeds as a sequential process, in two steps. The originally observed ternary decay of 252 Cf(sf) into three different masses (e.g. 132-140 Sn, 52-48 Ca, 68-72 Ni), observed by the FOBOS group in the FLNR (Flerov Laboratory for Nuclear Reactions) of the JINR (Dubna) the collinear cluster tripartition (CCT), is one of the ternary fission modes. This kind of "true ternary fission" of heavy nuclei has often been predicted in theoretical works during the last decades. In the present note we discuss different ternary fission modes in the same system. The PES shows pronounced minima, which correspond to several modes of ternary fragmentations. These decays have very similar dynamical features as the previously observed CCT-decays. The data obtained in the experiments on CCT allow us to extract the yields for different decay modes using specific gates on the measured parameters, and to establish multiple modes of the ternary fission decay.

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Section: Potential Energy Surface (Pes) Internal Barriers In Ternarymentioning

confidence: 99%

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

2015

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“…2. Potential energy surface calculations [29,40,41] predict that it is more likely that the TP is formed at the center. Nevertheless, we present results for both cases.…”

Section: A Sequential Decay Modelmentioning

confidence: 99%

“…If the ternary particle was formed on the outside, our results indicate that it would have a kinetic energy which is easily separated in a spectrometer, as there is no background of such fragments from binary fission. Several potential energy surface calculations [29,40,41] have shown, however, that it would be energetically favorable if the ternary particle was in the center position. In this configuration, all three models show that the kinetic energy of the ternary particle would be close to zero MeV.…”

Section: A Verification By Direct Observationmentioning

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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“…"Almost sequential" mechanism of true ternary fission is analyzed in detail in Ref [23]. The authors consider the collinear sequential ternary decay with a very short time between the ruptures of two necks connecting the middle cluster of the ternary nuclear system and outer fragments.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Examination of evidence for collinear cluster tri-partition

et al. 2017

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In a series of the experiments at different time-of-flight spectrometers of heavy ions we have observed manifestations of a new at least ternary decay channel of low excited heavy nuclei. Due to specific features of the effect, it was called collinear cluster tri-partition (CCT). The experimental results obtained initiated a number of theoretical articles dedicated to different aspects of the CCT. We compare theoretical predictions with our experimental data, only partially published so far. The model of one of the most populated CCT modes that gives rise to the so called "Ni-bump" is discussed. Detection of the 68-72Ni fission fragments with a kinetic energy E<25 MeV at the mass-separator Lohengrin is proposed for an independent experimental verification of the CCT.Comment: 16 pages, 14 figure

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Theoretical study of the almost sequential mechanism of true ternary fission

Cited by 23 publications

References 23 publications

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

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

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

Examination of evidence for collinear cluster tri-partition

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