Isotopic yields from the reaction 245Cm(nth,f) at the Lohengrin mass separator

Rochman, D.; Faust, H.; Tsekhanovich, I.; Gönnenwein, F.; Storrer, F.; Oberstedt, S.; Sokolov, V. E.

doi:10.1016/s0375-9474(02)01026-6

Cited by 26 publications

(23 citation statements)

References 20 publications

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“…In this paper, we show that the conservation of isospin explains in a strikingly precise manner the observed relative yields of pairs of fission fragments of each of the (Z 1 , Z 2 ) partitions measured in two recent heavy ion induced fusion-fission experiments [7,8] as well as the thermal neutron induced fission [9]. The work shows the validity of isospin conservation in the neutron-rich heavy nuclei [10,11] and also confirms the theoretical predictions of Lane and Soper.…”

Section: Introductionmentioning

confidence: 78%

“…2. We now discuss the thermal n-induced fission 245 Cm(n th , f ) [9]. The CN, 246 Cm, formed by the fusion of the neutron (| 1 2 , 1 2 ), with the target 245 Cm (| 53 2 , 53 2 ), has |T CN , T 3CN = |27, 27 .…”

Section: Resultsmentioning

confidence: 99%

“…The CN, 246 Cm, formed by the fusion of the neutron (| 1 2 , 1 2 ), with the target 245 Cm (| 53 2 , 53 2 ), has |T CN , T 3CN = |27, 27 . The authors [9] have mea- 0.017510 3.5 28.5…”

Section: Resultsmentioning

confidence: 99%

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Conservation of Isospin in Neutron-rich Fission Fragments

Choudhury

Maheshwari

2014

Nuclear Data Sheets

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On the occasion of the 75 th anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavyion reactions 238 U( 18 O,f) and 208 Pb( 18 O,f) as well as a thermal neutron fission reaction 245 Cm(n th ,f). We find that the conservation of the total isospin explains the overall trend in the observed relative yields of fragment masses in each fission pair partition. The isospin values involved are very large making the effect dramatic. The findings open the way for more precise calculations of fission fragment distributions in heavy nuclei and may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation of decay heat in the fission phenomenon.I.

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Section: Introductionmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

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Conservation of Isospin in Neutron-rich Fission Fragments

Choudhury

Maheshwari

2014

Nuclear Data Sheets

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“…13 of Ref. [118]. In the GEF model, the even-odd fluctuation of the TKE is calculated by a simple description following an idea of Ref.…”

Section: Total Kinetic Energymentioning

confidence: 99%

General Description of Fission Observables: GEF Model Code

Schmidt

Jurado

Amouroux

et al. 2016

Nuclear Data Sheets

446

421

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The GEF ("GEneral description of Fission observables") model code is documented. It describes the observables for spontaneous fission, neutron-induced fission and, more generally, for fission of a compound nucleus from any other entrance channel, with given excitation energy and angular momentum. The GEF model is applicable for a wide range of isotopes from Z = 80 to Z = 112 and beyond, up to excitation energies of about 100 MeV. The results of the GEF model are compared with fission barriers, fission probabilities, fission-fragment mass-and nuclide distributions, isomeric ratios, total kinetic energies, and prompt-neutron and prompt-gamma yields and energy spectra from neutron-induced and spontaneous fission. Derived properties of delayed neutrons and decay heat are also considered.The GEF model is based on a general approach to nuclear fission that explains a great part of the complex appearance of fission observables on the basis of fundamental laws of physics and general properties of microscopic systems and mathematical objects. The topographic theorem is used to estimate the fission-barrier heights from theoretical macroscopic saddle-point and ground-state masses and experimental ground-state masses. Motivated by the theoretically predicted early localisation of nucleonic wave functions in a necked-in shape, the properties of the relevant fragment shells are extracted. These are used to determine the depths and the widths of the fission valleys corresponding to the different fission channels and to describe the fission-fragment distributions and deformations at scission by a statistical approach. A modified composite nuclear-level-density formula is proposed. It respects some features in the superfluid regime that are in accordance with new experimental findings and with theoretical expectations. These are a constant-temperature behaviour that is consistent with a considerably increased heat capacity and an increased pairing condensation energy that is consistent with the collective enhancement of the level density. The exchange of excitation energy and nucleons between the nascent fragments on the way from saddle to scission is estimated according to statistical mechanics. As a result, excitation energy and unpaired nucleons are predominantly transferred to the heavy fragment in the superfluid regime. This description reproduces some rather peculiar observed features of the prompt-neutron multiplicities and of the even-odd effect in fission-fragment Z distributions. For completeness, some conventional descriptions are used for calculating pre-equilibrium emission, fission probabilities and statistical emission of neutrons and gamma radiation from the excited fragments. Preference is given to simple models that can also be applied to exotic nuclei compared to more sophisticated models that need precise empirical input of nuclear properties, e.g. spectroscopic information.The approach reveals a high degree of regularity and provides a considerable insight into the physics of the fission process. Fission obs...

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“…But still, isotopic identification is limited to the light group, for example Refs. [9][10][11], except during experiments where β-delayed γ-rays are measured [12]. This latter method allows to measure only some isotopic yields in the heavy group, and results on isotopic yields remain partial.…”

Section: Experimental Limitations Due To Direct Kinematicsmentioning

confidence: 99%

Accurate measurements of fission-fragment yields in^{234,235,236,238}U(γ,f) with the SOFIA set-up

Chatillon

Taïeb

Martin

et al. 2016

EPJ Web of Conferences

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Abstract. SOFIA (Studies On Fission with Aladin) is a new experimental set-up dedicated to accurate measurement of fission-fragments isotopic yields. It is located at GSI, the only place to use inverse kinematics at relativistic energies in order to study the (γ,f) electromagnetic-induced fission. The SOFIA set-up is a large-acceptance magnetic spectrometer, which allows to fully identify both fission fragments in coincidence on the whole fission-fragment range. This paper will report on fission yields obtained in 234,235,236,238 U(γ,f) reactions.

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Isotopic yields from the reaction 245Cm(nth,f) at the Lohengrin mass separator

Cited by 26 publications

References 20 publications

Conservation of Isospin in Neutron-rich Fission Fragments

Conservation of Isospin in Neutron-rich Fission Fragments

General Description of Fission Observables: GEF Model Code

Accurate measurements of fission-fragment yields in^{234,235,236,238}U(γ,f) with the SOFIA set-up

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Isotopic yields from the reaction 245Cm(nth,f) at the Lohengrin mass separator

Cited by 26 publications

References 20 publications

Conservation of Isospin in Neutron-rich Fission Fragments

Conservation of Isospin in Neutron-rich Fission Fragments

General Description of Fission Observables: GEF Model Code

Accurate measurements of fission-fragment yields in234,235,236,238U(γ,f) with the SOFIA set-up

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Product

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Accurate measurements of fission-fragment yields in^{234,235,236,238}U(γ,f) with the SOFIA set-up