Pre-scission configuration of the tri-nuclear system at spontaneous ternary fission of 252Cf

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

doi:10.1140/epja/i2016-16135-9

Cited by 16 publications

(29 citation statements)

References 21 publications

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“…Thus, even in a very late sequential decay, collinearity is in question. Assuming a sequential decay, Nasirov et al [49] showed that lateral offsets of the TP up to 2 fm are expected at scission, and Tashkhodjaev et al [50] confirmed that collinearity indeed can be broken.…”

Section: Collinear Stability Resultsmentioning

confidence: 98%

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: Collinear Stability Resultsmentioning

confidence: 98%

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

et al. 2017

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“…This model has been used extensively to investigate the different theoretical aspects of ternary fission for various isotopes of Cf, U, Pu and Cm [46][47][48][49][50][51]. Despite the macroscopic approach of three-cluster model, its predictions and the obtained results are in good agreement with the available experimental data and other models [52][53][54][55][56][57][58][59][60]. In our first publication [61], we studied the cold ternary fission of the 250 Cm by using three-cluster model in the equatorial geometry and considering light charged particles as the fixed third fragment.…”

Section: Introductionmentioning

confidence: 82%

Tin-accompanied and true ternary fission of ²⁴²Pu

2019

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True ternary fission and Tin-accompanied ternary fission of 242 Pu are studied by using 'Three Cluster Model '. True ternary fission is considered as formation of heavy fragments in the region 28 ≤ Z 1 , Z 2 , Z 3 ≤ 38, with comparable masses. The possible fission channels are predicted from potential-energy calculations. Interaction potentials, Q-values and relative yields for all possible fragmentations in equatorial and collinear configurations are calculated and compared to each other. It is found out that ternary fission with formation of a double magic nucleus like 132 Sn is more probable than the other fragmentations. Also the kinetic energies of the fragments for the group Z 1 = 32, Z 2 = 32 and Z 3 = 30 are calculated for all combinations in the collinear geometry, as a sequential decay.

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“…MeV. Larger estimates of the scission parameter d are reported for ternary fission with larger clusters such as 50 Ca [41] which will not be discussed here.…”

Section: External Mean-field Potentialmentioning

confidence: 91%

Light element ($Z=1,2$) production from spontaneous ternary fission of $^{252}$Cf

Röpke,

Natowitz,

Pais

2020

Preprint

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The yields of light elements (Z = 1, 2) obtained from spontaneous ternary fission of 252 Cf are treated within a nonequilibrium approach, and the contribution of unstable nuclei and excited bound states is taken into account. These light cluster yields may be used to probe dense matter, and to infer in-medium corrections. Continuum correlations are calculated from scattering phase shifts using the Beth-Uhlenbeck formula, and the effect of medium modification is estimated. The relevant distribution is reconstructed from the measured yields of isotopes. This describes the state of the nucleon system at scission and cluster formation, using only three Lagrange parameters which are the nonequilibrium counterparts of the temperature and chemical potentials, as defined in thermodynamic equilibrium. We concluded that a simple nuclear statistical equilibrium model neglecting continuum correlations and medium effects is not able to describe the measured distribution of H and He isotopes. Moreover, the freeze-out concept may serve as an important ingredient to the nonequilibrium approach using the relevant statistical operator concept.

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Pre-scission configuration of the tri-nuclear system at spontaneous ternary fission of 252Cf

Cited by 16 publications

References 21 publications

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

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

Tin-accompanied and true ternary fission of ²⁴²Pu

Light element ($Z=1,2$) production from spontaneous ternary fission of $^{252}$Cf

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Pre-scission configuration of the tri-nuclear system at spontaneous ternary fission of 252Cf

Cited by 16 publications

References 21 publications

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

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

Tin-accompanied and true ternary fission of 242Pu

Light element ($Z=1,2$) production from spontaneous ternary fission of $^{252}$Cf

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Tin-accompanied and true ternary fission of ²⁴²Pu