Accurate isotopic fission yields of electromagnetically induced fission of 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">U</mml:mi><mml:mprescripts /><mml:none /><mml:mn>238</mml:mn></mml:mmultiscripts></mml:math>
 measured in inverse kinematics at relativistic energies

Pellereau, E.; Taïeb, J.; Chatillon, A.; Álvarez‐Pol, H.; Audouin, L.; Ayyad, Y.; Bélier, G.; Benlliure, J.; Boutoux, G.; Caamaño, M.; Casarejos, E.; Cortina-Gil, D.; Ebran, A.; Farget, F.; Fernández–Domínguez, B.; Gorbinet, T.; Grente, L.; Heinz, A.; Johansson, H.; Jurado, B.; Kelić-Heil, A.; Kurz, N.; Bouchet, L.; Martin, Julie-Fiona; Nociforo, C.; Paradela, C.; Piétri, S.; Rodríguez-Sànchez, J. L.; Schmidt, Karl‐Heinz; Simon, H.; Tassan‐Got, L.; Vargas, J. E. Ramirez; Voss, B.; Weick, H.

doi:10.1103/physrevc.95.054603

Cited by 56 publications

(42 citation statements)

References 34 publications

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“…The Brownian shapemotion model with random walks on 5D potential-energy surfaces [42] predicts a continuous increase of the yield for Sn for heavier fissioning systems in the isotopic chain of uranium, for initial excitation energy around ∼ 1MeV above the fission barrier. Similar values are also obtained [25,26] (open circles) are compared with a model based on the Brownian shape-motion and on 5D potentialenergy surfaces [42] (dashed line) and with the GEF code (2018/1.1) [38] (solid line). Data from γ-spectroscopy measurement Ref.…”

supporting

confidence: 64%

“…The use of inverse kinematics allowed the direct measurement of the atomic number of complete fission-fragment distributions [22]. In the last decade, the simultaneous use of surrogate reactions, inverse kinematics, and magnetic spectrometers has opened a new field of study measuring complete isotopic fission-fragment distributions [23][24][25][26], and leading to an improved understanding of the fission process [12].…”

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confidence: 99%

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First Direct Measurement of Isotopic Fission-Fragment Yields of U239

Ramos¹,

Caamaño²,

Lemasson³

et al. 2019

Phys. Rev. Lett.

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A direct and complete measurement of isotopic fission-fragment yields of 239 U has been performed for the first time. The 239 U fissioning system was produced with an average excitation energy of 8.3 MeV in one-neutron transfer reactions between a 238 U beam and a 9 Be target at Coulomb barrier energies. The fission fragments were detected and isotopically identified using the VAMOS++ spectrometer at the GANIL facility. This measurement allows to directly evaluate the fission models at excitation energies of fast neutrons, relevant for next-generation nuclear reactors. The present data, in agreement with model calculations, do not support the recently reported anomaly in the fission-fragment yields of 239 U and confirm the persistence of spherical shell effects in the Sn region at excitation energies exceeding the fission barrier by few MeV.

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confidence: 64%

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confidence: 99%

First Direct Measurement of Isotopic Fission-Fragment Yields of U239

Ramos¹,

Caamaño²,

Lemasson³

et al. 2019

Phys. Rev. Lett.

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“…Both the masses of the fragments and the average neutron multiplicity were not accessible in this kind of experiments. Starting from the same reaction mechanism but using a much more advanced experimental setup, the SOFIA experiments at GSI Darmstadt now allow one to obtain both charge and mass fission yields with an accuracy smaller than a mass unit as well as the average neutron multiplicity ν [56,57]. Other techniques have been developed in parallel to study the fission of exotic nuclei.…”

Section: Resultsmentioning

confidence: 99%

“…The tensor interaction rearranges the position of the single particle orbitals changing the shell effects responsible for many of the properties of the quantities relevant to fission. In fact, it could be the missing ingredient required to explain a symmetric bimodal fission mode recently found in some neutron-deficient thorium isotopes [56][57][58][59]. Recent experimental data provided by the experiments of the SOFIA collaboration have revealed the existence of such a symmetric bimodal mode, composed of the standard super-long mode and a new compact mode.…”

Section: Introductionmentioning

confidence: 95%

Description of the asymmetric to symmetric fission transition in the neutron-deficient thorium isotopes: Role of the tensor force

et al. 2020

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In the present study, we have investigated the impact of the tensor force on fission paths, in particular the symmetric and asymmetric barriers in 230 Th, 226 Th, 222 Th and 216 Th isotopes which display an asymmetric to symmetric fission transition. This analysis has been performed within the HFB approach with (Q20,Q30,Q40) as collective variable constraints, using the D1ST2a Gogny+tensor term interaction and comparing to the standard D1S Gogny interaction results. The effects from the tensor term on the potential energy surface landscape, and especially on barrier heights and its topology by opening a new valley in agreement with experimental data, are found to be crucial in the description of exotic actinide fission. We conclude that a tensor term should be integrated to the long range part of the effective interaction for a better description of the fission.

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“…In the case of 227 Ac, however, the fitted FWHM mass distribution width is much higher (12 mass units), allowing the symmetric peak to be detected in in-beam experiments. It may be mentioned that exact atomic number and mass number determination are indeed possible in in-beam fission studies using inverse kinematics and fragment separators but such studies [27] are so far limited to fragment yield determination in electromagnetically induced fission of 238 U having mean excitation less than 15 MeV.…”

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Signature of bi-modal fission in uranium nuclei

Dechoudhury¹,

Bhowmick²,

Naik³

2019

J. Phys. G: Nucl. Part. Phys.

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We report here the signature of bi-modal fission, one asymmetric and the other symmetric, in Uranium nuclei in the mass range A = 230 to 236. The finding is unexpected and striking and is based on a model independent analysis of experimental mass distributions (cumulative yields) at various excitations from about 23 to 66 MeV in the α induced fission of 232 Th. It has been found that the observed asymmetry in the mass distributions and the unusually narrow peak in the symmetry region, can both be explained in a consistent manner if one assumes: a) multi-chance fission, b) bi-modal fission at lower excitations (9 < E* < 25 MeV) for all the Uranium nuclei in the range A = 230 to 236, and c) that the shell effects get washed out completely beyond about 25 MeV of excitation resulting in symmetric fission. The analysis has allowed a quantitative estimation of the percentages of the asymmetric and the symmetric component in the bi-modal fission. It has been found that the bi-modal fission in Uranium nuclei is predominantly asymmetric (~ 85%), which contributes in a major way to the observed asymmetric peaks, while the ~15% bi-modal symmetric fission is primarily responsible for the observed narrow symmetric peak in the mass distributions. The unusually narrow symmetry peak in the mass distributions indicates that the symmetric bi-modal fission in Uranium nuclei must have proceeded from a configuration at the bi-modal symmetric saddle that is highly deformed with a well-developed neck. Corresponding author email: alok@vecc.gov.inIt is well known that the liquid drop model [1 -3] only leads to symmetric division of the fissioning nucleus into two fragments of equal mass. To explain the observed highly asymmetric mass distribution in fission of actinides, especially in thermal neutron induced fission of 235 U, the liquid drop potential energy needs to be corrected for the shell and pairing effects [4]. The spherical shell corresponding to major shell closure at N=82 (doubly magic 132 Sn) and deformed shell corresponding to N=88 appear to play a major role in the asymmetric split. However, it has

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Accurate isotopic fission yields of electromagnetically induced fission of U238 measured in inverse kinematics at relativistic energies

Cited by 56 publications

References 34 publications

First Direct Measurement of Isotopic Fission-Fragment Yields of U239

First Direct Measurement of Isotopic Fission-Fragment Yields of U239

Description of the asymmetric to symmetric fission transition in the neutron-deficient thorium isotopes: Role of the tensor force

Signature of bi-modal fission in uranium nuclei

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