Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction

Meitner, Lise; Frisch, O. R.

doi:10.1038/143239a0

Cited by 611 publications

(256 citation statements)

References 6 publications

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“…Our present understanding of nuclear fission is still based on the idea of Lisa Meitner and Otto Frisch [1] of a deformed charged liquid drop. In a seminal paper [2] Niels Bohr and John A. Wheeler fully developed the concept of the energy surface of a nucleus as function of a set of deformation parameters.…”

Section: Introductionmentioning

confidence: 99%

Fission fragment mass and total kinetic energy distributions of spontaneously fissioning plutonium isotopes

Pomorski

Nerlo-Pomorska

Bartel³

et al. 2018

EPJ Web Conf.

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Abstract. The fission-fragment mass and total kinetic energy (TKE) distributions are evaluated in a quantum mechanical framework using elongation, mass asymmetry, neck degree of freedom as the relevant collective parameters in the Fourier shape parametrization recently developed by us. The potential energy surfaces (PES) are calculated within the macroscopic-microscopic model based on the Lublin-Strasbourg Drop (LSD), the Yukawa-folded (YF) single-particle potential and a monopole pairing force. The PES are presented and analysed in detail for even-even Plutonium isotopes with A = 236-246. They reveal deep asymmetric valleys. The fission-fragment mass and TKE distributions are obtained from the ground state of a collective Hamiltonian computed within the BornOppenheimer approximation, in the WKB approach by introducing a neck-dependent fission probability. The calculated mass and total kinetic energy distributions are found in good agreement with the data.

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Section: Introductionmentioning

confidence: 99%

Fission fragment mass and total kinetic energy distributions of spontaneously fissioning plutonium isotopes

Pomorski

Nerlo-Pomorska

Bartel³

et al. 2018

EPJ Web Conf.

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“…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].…”

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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“…Taking into account the liquiddrop model, which had been developed several years before, as well as the theory of the "compound" nucleus, derived from the liquid-drop model by Niels Bohr three years before, they provided the physical explanation for nuclear fission: nuclear fission was indeed plausible within the boundaries of the already existing theories of physics. Meitner and Frisch submitted their paper on 16 January 1939 to the English journal Nature and it appeared in the 11 February issue [15].…”

Section: Horst Kantmentioning

confidence: 99%

Lise Meitner and the (supposed) transuranic elements

Kant

2012

Annalen der Physik

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Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction

Cited by 611 publications

References 6 publications

Fission fragment mass and total kinetic energy distributions of spontaneously fissioning plutonium isotopes

Fission fragment mass and total kinetic energy distributions of spontaneously fissioning plutonium isotopes

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

Lise Meitner and the (supposed) transuranic elements

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