Aspects of charge distribution measurement for 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Cf</mml:mi><mml:mprescripts /><mml:none /><mml:mn>252</mml:mn></mml:mmultiscripts></mml:math>
(sf)

Wang, Taofeng; Li, Guangwu; Zhu, Liping; Hen, O.; Zhang, Gaolong; Meng, Qingwei; Wang, Liming; Haihong, Xia

doi:10.1103/physrevc.96.034611

Cited by 3 publications

(5 citation statements)

References 25 publications

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“…These unexpected observations triggered several experiments with different techniques (heavyion fusion-fission reactions and electro magnetic-induced fission in inverse kinematics) and a number of theoretical works with self-consistent and stochastic models, which will be described in detail in the following. Again, by the study of beta-delayed fission at ISOLDE, Ghys et al [154] found single-humped fission-fragment mass distributions in the beta-delayed fission of the daughter nucleus 194 Po and indications for triple-humped distributions for 196 Po and 202 Rn. Asymmetric fission was observed following the population of 182 Hg at an excitation energy of 22.8 MeV above the saddle point, while symmetric fission was observed for 195 Hg nuclei at a similar excitation energy above the saddle point in heavyion fusion-fission reactions [175].…”

Section: Accessible Fissionable Nucleimentioning

confidence: 99%

“…A pronounced double-humped mass distribution was found for the fission fragments of the compound nucleus 180 Hg, formed as the daughter nucleus after the beta decay of 180 Tl, which has similarities with the double-humped mass distribution observed previously by Itkis et al [254] for the fission of excited 201 Tl, which is situated close to beta stability, in an alpha-induced reaction. Fission-fragment mass distributions have also been studied in the beta-delayed fission of the daughter nuclei 178 Hg and 194,196 Po at ISOLDE and 202 Rn at SHIP (GSI) [252], where asymmetric fission or complex shapes were observed. These unexpected observations triggered several experiments with different techniques (heavyion fusion-fission reactions and electro magnetic-induced fission in inverse kinematics) and a number of theoretical works with self-consistent and stochastic models, which will be described in detail in the following.…”

Section: Accessible Fissionable Nucleimentioning

confidence: 99%

“…For most of these distributions, the mean masses of the asymmetric components and their uncertainties were determined in [154]. The measured pre-neutron fission-fragment mass distributions from the beta-delayed fission of the compound nuclei 180 Hg, 194 Po, 196 Po and 202 Rn [143,154] (full black symbols) in comparison with the result of the GEF code (GEF 2017/V1.2) (open red symbols). Figures 25 and 26 show the deduced mean positions of these peaks in neutron and proton number, respectively, both in the light and in the heavy fragment as a function of the number N CN of neutrons in the fissioning nucleus.…”

Section: Hidden Regularities Of Fission Channelsmentioning

confidence: 99%

“…Figure 23. The measured pre-neutron fission-fragment mass distributions from the beta-delayed fission of the compound nuclei180 Hg,194 Po,196 Po and 202 Rn[143,154] (full black symbols) in comparison with the result of the GEF code (GEF 2017/V1.2) (open red symbols).…”

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Review on the progress in nuclear fission—experimental methods and theoretical descriptions

2018

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An overview is given on some of the main advances in the experimental methods, experimental results, theoretical models and ideas of the last few years in the field of nuclear fission. New approaches have considerably extended the availability of fissioning systems for the experimental study of nuclear fission, and have provided a full identification of all fission products in A and Z for the first time. In particular, the transition from symmetric to asymmetric fission around Th, some unexpected structures in the mass distributions in the fission of systems around Z = 80-84, and an extended systematics of the odd-even effect in the fission fragment Z distributions have all been measured (Andreyev et al 2018 Rep. Prog. Phys. 81 016301). Three classes of model descriptions of fission presently appear to be the most promising or the most successful. Self-consistent quantum-mechanical models fully consider the quantum-mechanical features of the fission process. Intense efforts are presently being made to develop suitable theoretical tools (Schunck and Robledo 2016 Rep. Prog. Phys. 79 116301) for modeling the non-equilibrium, large-amplitude collective motion leading to fission. Stochastic models provide a fully developed technical framework. The main features of the fission-fragment mass distribution have been well reproduced from mercury to fermium and beyond (Möller and Randrup 2015 Phys. Rev. C 91 044316). However, limited computer resources still impose restrictions, for example, on the number of collective coordinates and on an elaborate description of the fission dynamics. In an alternative semi-empirical approach (Schmidt et al 2016 Nucl. Data Sheets 131 107), considerable progress in describing the fission observables has been achieved by combining several theoretical ideas, which are essentially well known. This approach exploits (i) the topological properties of a continuous function in multidimensional space, (ii) the separability of the influence of fragment shells and the macroscopic properties of the compound nucleus, (iii) the properties of a quantum oscillator coupled to a heat bath of other nuclear degrees of freedom, (iv) an early freeze-out of collective motion, and (v) the application of statistical mechanics for describing the thermalization of intrinsic excitations in the nascent fragments. This new approach reveals a high degree of regularity and allows the calculation of high-quality data that is relevant to nuclear technology without specifically adjusting the empirical data of individual systems.

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Section: Accessible Fissionable Nucleimentioning

confidence: 99%

Section: Accessible Fissionable Nucleimentioning

confidence: 99%

Section: Hidden Regularities Of Fission Channelsmentioning

confidence: 99%

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confidence: 99%

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Review on the progress in nuclear fission—experimental methods and theoretical descriptions

2018

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“…Isotope FPY data is scarce due to methodical difficulties in fragment spectroscopy. For 252 Cf SF it exists mainly in the low fission peak (A ∼ 80-125) due to limited resolution in Z [11]. Experimental data on the high fission peak is limited to 'cold fission' (i.e.…”

Section: Introductionmentioning

confidence: 99%

Determining spontaneous fission properties by direct mass measurements with the FRS Ion Catcher

et al. 2020

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We present a direct method to measure fission product yield distributions (FPY) and isomeric yield ratios (IYR) for spontaneous fission (SF) fragments. These physical properties are of utmost importance to the understanding of basic nuclear physics, the astrophysical rapid neutron capture process ('r process') of nucleosynthesis, neutron star composition, and nuclear reactor safety. With this method, fission fragments are produced by spontaneous fission from a source that is mounted in a cryogenic stopping cell (CSC), thermalized and stopped within it, and then extracted and transported to a multiple-reflection time-of-flight mass-spectrometer (MR-TOF-MS). We will implement the method at the FRS Ion Catcher (FRS-IC) at GSI (Germany), whose MR-TOF-MS relative mass accuracy (~ 10-7) and resolving power (~ 600,000 FWHM) are sufficient to separate all isobars and numerous isomers in the fission fragment realm. The system's essential element independence and its fast simultaneous mass measurement provide a new direct way to measure isotopic FPY distributions, which is complementary to existing methods. It will enable nuclide FPY measurements in the high fission peak, which is hardly accessible by current techniques. The extraction time of the CSC, tens of milliseconds, enables a direct measurement of independent fission yields, and a first study of the temporal dependence of FPY distributions in this duration range. The ability to resolve isomers will further enable direct extraction of numerous IYRs while performing the FPY measurements. The method has been recently demonstrated at the FRS-ICr for SF with a 37 kBq 252Cf fission source, where about 70 different fission fragments have been identified and counted. In the near future, it will be used for systematic studies of SF with a higher-activity 252Cf source and a 248Cm source. The method can be implemented also for neutron induced fission at appropriate facilities.

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K X-ray emission and kinetic energy-nuclear charge relationship of 252Cf spontaneous fission

Liu,

Yang

et al. 2024

Acta Phys. Sin.

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Experimentally investigations of physical quantities after fission offer crucial insights into the fission process, which is an indispensable way to test the fission theory. Among them, the characteristics of primary fission products before beta decay are of great value to unraveling fission kinematics and nuclear energy applications. However, the measurement of the fragment charge has always been challenging. Multi-parameter studies related to nuclear charge remain relatively scarce. The deexcitation of the primary fission products may undergo internal conversion and are often accompanied by characteristic X-ray emissions, to this end, the correlated measurement of fragment kinetic energies and K X-rays for 252Cf spontaneous fission was conducted. A silicon surface barrier detector was employed to measure the fragment kinetic energy, while two Low-Energy high-pure Germanium Detectors (LEGe) were utilized for K X-ray measurement. Identification of fission fragments with Z=39~62 was realized through characteristic K X-rays with a charge resolution of ΔZ≈0.7. Fission fragment K X-ray yields exhibit a strong charge correlation, with an odd-even effect factor of approximately 13%. Based on K X-rays, the post-neutron-emission average kinetic energy, average total kinetic energy (< TKE >), and its dispersion (σTKE) of fission fragments were determined as a function of nuclear charge. The kinetic energy distribution of light fragments shows a pronounced odd-even effect, with even-Z elements exhibiting kinetic energies enhanced by around 0.48 MeV compared to odd-Z fragments. The peak of the < TKE > distribution is near Z=52~53, while the minimum of the σTKE appears near Z=56, indicating the significant influence of deformed shells in the highly asymmetric fission region. The post-neutron kinetic energy distribution of fission fragments from 252Cf(sf) was calculated using the GEF and CGMF models. The CGMF model effectively reproduces the overall trend of kinetic energy as a function of charge number, while the results of the GEF calculation are systematically higher than the experimental value. Nonetheless, these two phenomenological models make it difficult to quantitatively describe the kinetic energy distribution of fission fragments accurately. Insights into K X-ray emissions and kinetic energy-nuclear charge relationships offer valuable reference data for independent fission yield measurements and the verification of fission theoretical models.

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Aspects of charge distribution measurement for Cf252 (sf)

Cited by 3 publications

References 25 publications

Review on the progress in nuclear fission—experimental methods and theoretical descriptions

Review on the progress in nuclear fission—experimental methods and theoretical descriptions

Determining spontaneous fission properties by direct mass measurements with the FRS Ion Catcher

K X-ray emission and kinetic energy-nuclear charge relationship of <sup>252</sup>Cf spontaneous fission

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