Spontaneous fission properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Fm</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>258</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Md</mml:mi></mml:mrow><mml:mpresc

Abstract. Static self-consistent methods usually allow to determine the most probable fission fragments mass asymmetry. We have applied random neck rupture mechanism to the nuclei in the configuration at the end of fission paths. Fission fragment mass distributions have been deduced from the prescission nuclear density distribution obtained from the self-consistent calculations. Potential energy surfaces as well as nuclear shapes have been calculated in the fully microscopic theory, namely the constrained Hartree-Fock-Bogolubov model with the effective Gogny D1S density-dependent interaction. The method has been applied for analysis of fission of 256,258 Fission fragment mass yield deduced from density distribution in the pre-scission configuration 2

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“…It was shown, that fission in 258 Fm represents specific, bimodal character [30,31]. Its mass yield is very narrow with a single peak.…”

Section: Resultsmentioning

confidence: 99%

Fission fragment mass yield deduced from density distribution in the pre-scission configuration

Warda

Zdeb

2015

Phys. Scr.

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“…However, nuclei such as 258 Fm and 259,260 Md exhibit complex MDs, each with a narrow and a broad symmetric component with a higher and lower TKE, respectively. This phenomenon is called bimodal fission [12][13][14][15]. Competition between symmetric and asymmetric fission, corresponding to respectively lower and higher TKE and resulting in a triple-humped MD has been reported around 226 Th [16][17][18].…”

mentioning

confidence: 99%

“…The indication of triple-humped MDs and breadth of the extracted TKE suggest the presence of at least two distinct fission modes each having different mass and TKE distributions. This feature was therefore further investigated by discriminating between fission events with high or low TKE, similar to the method described in [12,13] used to illustrate bimodal fission in the transfermium region. In Fig.…”

mentioning

confidence: 99%

Evolution of fission-fragment mass distributions in the neutron-deficient lead region

Ghys¹,

Andreyev²,

Huyse³

et al. 2014

Phys. Rev. C

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Low-energy β-delayed fission of 194,196 At and 200,202 Fr was studied in detail at the mass separator ISOLDE at CERN. The fission-fragment mass distributions of daughter nuclei 194,196 Po and 202 Rn indicate a triple-humped structure, marking the transition between asymmetric fission of 178,180 Hg and symmetric fission in the light Ra-Rn nuclei. Comparison with the macroscopic-microscopic finite-range liquid-drop model and the self-consistent approach employing the Gogny D1S energy density functional yields discrepancies. This demonstrates once more the need of dynamical fission calculations, as for both models the potential-energy surfaces lack pronounced structures, in contrast to the actinide region.Nuclear fission, the division of a heavy atomic nucleus into predominantly two parts, continues to provide new and unexpected features in spite of a long history of intensive theoretical and experimental studies [1][2][3][4][5][6][7]. The fission process is not only important for several applications, such as energy production and radiopharmacology, but also has a direct impact on the understanding of the fission recycling process in r -process nucleosynthesis [8,9]. Therefore, a description of the fission process with reliable predictive power is needed, in particular for low-energy fission where the fission-fragment (FF) mass distributions are strongly * lars.ghys@fys.kuleuven.be sensitive to microscopic effects [4]. Mass distributions (MDs) are usually predominantly symmetric or asymmetric with the yields exhibiting a single peak or two distinct peaks, respectively. However, in several cases a mixture of two modes was observed [5]. Experimental observables characterizing various fission modes are the width of the MD peak(s), the position of these peaks in asymmetric mass division and total kinetic energy (TKE) of the FFs. The dominance of asymmetric fission in most of the actinide region beyond A = 226 up to about 256 Fm was attributed to strong microscopic effects of the heavier FF, near the doubly-magic 132 Sn [4,10,11]. However, nuclei such as 258 Fm and 259,260 Md exhibit complex MDs, each with a narrow and a broad symmetric component with a higher and lower TKE, respectively. 2This phenomenon is called bimodal fission [12][13][14][15]. Competition between symmetric and asymmetric fission, corresponding to respectively lower and higher TKE and resulting in a triple-humped MD has been reported around 226 Th [16][17][18]. These observations strongly support the hypothesis that nuclei may fission through several independent fission modes corresponding to different pre-scission shapes and fission paths in a multidimensional potential-energy landscape, referred to in literature as multimodal or multichannel fission [4,5,11,[16][17][18][19]. In the pre-actinide region, predominantly symmetric FF mass distributions were measured. A few relevant cases for the present discussion (see also Fig.1) are 195 Au, 198 Hg and 208,210 Po, studied by means of charged-particle induced reactions [20][21][22] and 204,206,...

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“…A modified version of the code EV8 [8] has been used, where two of the reflection symmetry have been removed allowing the octupole deformation necessary to study asymmetric fission. As a test case, we study the 258 Fm fission where experimental data are available [9]. In the literature, three modes are considered: a symmetric fission with compact fragments, a symmetric fission with elongated fragments and an asymmetric fission.…”

Section: The Fission Processmentioning

confidence: 99%

Microscopic description of²⁵⁸Fm fission dynamic with pairing

Scamps

Simenel

Lacroix

2016

EPJ Web of Conferences

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Fission dynamic remains a challenge for nuclear microscopic theories. In order to understand the dynamic of the last stage of the fission process, the time-dependent Hartree-Fock approach with BCS pairing is applied to the describe the fission of the 258 Fm. A good agreement is found for the one-body observables: the total kinetic energy and the average mass asymmetry. The non-physical dependence of two-body observables with the initial shape is discussed.

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Spontaneous fission properties ofFm258,Md

Cited by 156 publications

References 45 publications

Fission fragment mass yield deduced from density distribution in the pre-scission configuration

Fission fragment mass yield deduced from density distribution in the pre-scission configuration

Evolution of fission-fragment mass distributions in the neutron-deficient lead region

Microscopic description of²⁵⁸Fm fission dynamic with pairing

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Spontaneous fission properties ofFm258,Md

Cited by 156 publications

References 45 publications

Fission fragment mass yield deduced from density distribution in the pre-scission configuration

Fission fragment mass yield deduced from density distribution in the pre-scission configuration

Evolution of fission-fragment mass distributions in the neutron-deficient lead region

Microscopic description of258Fm fission dynamic with pairing

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Microscopic description of²⁵⁸Fm fission dynamic with pairing