Have superheavy elements been produced in nature?

Petermann, I.; Langanke, K.; Martı́nez-Pinedo, G.; Panov, I. V.; Reinhard, P.‐G.; Thielemann, Friedrich‐Karl

doi:10.1140/epja/i2012-12122-6

Cited by 87 publications

(88 citation statements)

References 119 publications

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“…With the fission methodology implemented here the super-heavy regime (A > 270) can be studied using r-Java 2.0. The preliminary study undertaken here supports the findings of Petermann et al (2012), where super-heavy nuclei (A ∼ 290) can be formed by the r-process. The super-heavies subsequently decay in seconds.…”

Section: Discussionsupporting

confidence: 88%

The r-Java 2.0 code: nuclear physics

Kostka

Koning

Shand

et al. 2014

A&A

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Aims. We present r-Java 2.0, a nucleosynthesis code for open use that performs r-process calculations, along with a suite of other analysis tools. Methods. Equipped with a straightforward graphical user interface, r-Java 2.0 is capable of simulating nuclear statistical equilibrium (NSE), calculating r-process abundances for a wide range of input parameters and astrophysical environments, computing the mass fragmentation from neutron-induced fission and studying individual nucleosynthesis processes. Results. In this paper we discuss enhancements to this version of r-Java, especially the ability to solve the full reaction network. The sophisticated fission methodology incorporated in r-Java 2.0 that includes three fission channels (beta-delayed, neutron-induced, and spontaneous fission), along with computation of the mass fragmentation, is compared to the upper limit on mass fission approximation. The effects of including beta-delayed neutron emission on r-process yield is studied. The role of Coulomb interactions in NSE abundances is shown to be significant, supporting previous findings. A comparative analysis was undertaken during the development of r-Java 2.0 whereby we reproduced the results found in the literature from three other r-process codes. This code is capable of simulating the physical environment of the high-entropy wind around a proto-neutron star, the ejecta from a neutron star merger, or the relativistic ejecta from a quark nova. Likewise the users of r-Java 2.0 are given the freedom to define a custom environment. This software provides a platform for comparing proposed r-process sites.

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Section: Discussionsupporting

confidence: 88%

The r-Java 2.0 code: nuclear physics

Kostka

Koning

Shand

et al. 2014

A&A

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“…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].…”

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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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“…These nuclei are important for analysis of the r-process in stars [35][36][37]. As in the previous Sec.…”

Section: Two-neutron Drip Linementioning

confidence: 77%

“…This part of the nuclear chart is important for the study of the r-process in stars [35][36][37]. The consideration is made within a standard approach with fixed EDF parameters found mainly for stable nuclei.…”

Section: Discussionmentioning

confidence: 99%

“…Recent interest to the problem of fixing the neutron drip line [33,34] is partially induced with importance of this characteristic of the nuclear chart for analysis of the r-process dynamics in stars [35][36][37]. A couple of remarks should be made concerning validity of the EDF method with fixed set of parameters for predicting the drip lines.…”

Section: Introductionmentioning

confidence: 99%

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Fayans functional for deformed nuclei. Uranium region

Tolokonnikov

Borzov

Kortelainen

et al. 2016

EPJ Web of Conferences

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Abstract. Fayans energy density functional (EDF) FaNDF 0 has been applied to the nuclei around uranium region. Ground state characteristics of the Th, U and Pu isotopic chains, up to the two-neutron drip line, are found and compared with predictions from several Skyrme EDFs. The two-neutron drip line is found for FaNDF 0 , SLy4 and SkM * EDFs for a set of elements with even proton number, from Pb up to Fm.

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Have superheavy elements been produced in nature?

Cited by 87 publications

References 119 publications

The r-Java 2.0 code: nuclear physics

The r-Java 2.0 code: nuclear physics

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

Fayans functional for deformed nuclei. Uranium region

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