| 1. |
- Ciemala, M., et al.
(author)
-
Testing ab initio nuclear structure in neutron-rich nuclei : Lifetime measurements of second 2(+) state in C-16 and O-20
- 2020
-
In: Physical Review C. - : AMER PHYSICAL SOC. - 2469-9985 .- 2469-9993. ; 101:2
-
Journal article (peer-reviewed)abstract
- To test the predictive power of ab initio nuclear structure theory, the lifetime of the second 2(+) state in neutron-rich O-20, tau(2(2)(+)) = 150(-30)(+80) fs, and an estimate for the lifetime of the second 2(+) state in C-16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O-18 (7.0 MeV/u) + Ta-181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced gamma-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O-20 and with the no-core shell model for C-16. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles nuclear structure calculations, complementing common benchmarks based on nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available.
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| 2. |
- Girard-Alcindor, V., et al.
(author)
-
New narrow resonances observed in the unbound nucleus F 15
- 2022
-
In: Physical Review C. - : American Physical Society (APS). - 2469-9985 .- 2469-9993. ; 105:5
-
Journal article (peer-reviewed)abstract
- The structure of the unbound F15 nucleus is investigated using the inverse kinematics resonant scattering of a radioactive O14 beam impinging on a CH2 target. The analysis of H1(O14,p)O14 and H1(O14,2p)N13 reactions allowed the confirmation of the previously observed narrow 1/2- resonance, near the two-proton decay threshold, and the identification of two new narrow 5/2- and 3/2- resonances. The newly observed levels decay by 1p emission to the ground of O14, and by sequential 2p emission to the ground state of N13 via the 1- resonance of O14. Gamow shell model (GSM) analysis of the experimental data suggests that the wave functions of the 5/2- and 3/2- resonances may be collectivized by the continuum coupling to nearby 2p- and 1p-decay channels. The observed excitation function H1(O14,p)O14 and resonance spectrum in F15 are well reproduced in the unified framework of the GSM.
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| 3. |
- Schlegel, C, et al.
(author)
-
K-isomers in very neutron-rich nuclei around mass 180
- 2000
-
In: Physica Scripta. Topical Issues. - 0281-1847. ; T88, s. 72-76
-
Journal article (peer-reviewed)abstract
- gamma-spectroscopy methods have been used to search for microsecond isomers among the fragmentation products of a 1 GeV/nucleon Pb-208 beam. In particular the population of the known K-pi = 35/2(-) isomer in W-179 has been investigated and several new isomeric decays have been found for neutron rich nuclei in the A approximate to 180-200 mass region. The ground state band of the neutron rich N = 116 system of W-190 has been identified for the first time and we discuss its structure in comparison to neighboring systems.
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| 4. |
- Perez-Vidal, R. M., et al.
(author)
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Evidence of Partial Seniority Conservation in the pi g9/2 Shell for the N=50 Isotones
- 2022
-
In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 129:11
-
Journal article (peer-reviewed)abstract
- The reduced transition probabilities for the 4+1 -2+1 and 2+1 -0+1 transitions in 92Mo and 94Ru and for the 4+1 -2+1 and 6+1 -4+1 transitions in 90Zr have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the f5=2, p3=2, p1=2, and g9=2 proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the N = 50 g9=2 orbital to be understood. The conclusion is that seniority is largely conserved in the first 71g9=2 orbital.
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| 5. |
- Zanon, I., et al.
(author)
-
High-Precision Spectroscopy of 20O Benchmarking Ab Initio Calculations in Light Nuclei
- 2023
-
In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 131:26
-
Journal article (peer-reviewed)abstract
- The excited states of unstable 20O were investigated via γ-ray spectroscopy following the 19O(d,p)20O reaction at 8 AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2+2 and 3+1 states were firmly established. From the γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2+2 and 3+1 states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.
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| 6. |
- Caamano, M, et al.
(author)
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Isomers in neutron-rich A approximate to 190 nuclides from Pb-208 fragmentation
- 2005
-
In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 23:2, s. 201-215
-
Journal article (peer-reviewed)abstract
- Relativistic projectile fragmentation of Pb-208 has been used to produce isomers in neutron-rich, A approximate to 190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of gamma-rays emitted by stopped ions has led to the assignment of isomers in Ta-188, W-190, Re-192, Re-193, Os-195, Ir-197, Ir-198, Pt-200, Pt-201, Pt-202 and Au-203, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for Er-174, Er-175, Hf-185, Re-191, Re-194 and Ir-199. In most cases, time-correlated, singles gamma-ray events provided the first spectroscopic data on excited states for each nuclide. In Pt-200 and Pt-201. the assignments are supported by gamma-gamma coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics.
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| 7. |
- Biswas, S., et al.
(author)
-
Effects of one valence proton on seniority and angular momentum of neutrons in neutron-rich(51)( 122-)(131)Sb isotopes
- 2019
-
In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 99:6
-
Journal article (peer-reviewed)abstract
- Background: Levels fulfilling the seniority scheme and relevant isomers are commonly observed features in semimagic nuclei; for example, in Sn isotopes (Z = 50). Seniority isomers in Sn, with dominantly pure neutron configurations, directly probe the underlying neutron-neutron (vv) interaction. Furthermore, an addition of a valence proton particle or hole, through neutron-proton (v pi) interaction, affects the neutron seniority as well as the angular momentum. Purpose: Benchmark the reproducibility of the experimental observables, like the excitation energies (E-x) and the reduced electric-quadrupole transition probabilities [B(E2)], with the results obtained from shell-model interactions for neutron-rich Sn and Sb isotopes with N < 82. Study the sensitivity of the aforementioned experimental observables to the model interaction components. Furthermore, explore from a microscopic point of view the structural similarity between the isomers in Sn and Sb, and thus the importance of the valence proton. Methods: The neutron-rich Sb122-131 isotopes were produced as fission fragments in the reaction Be-9(U-238, f) with 6.2 MeV/u beam energy. A unique setup, consisting of AGATA, VAMOS++, and EXOGAM detectors, was used which enabled the prompt-delayed gamma-ray spectroscopy of fission fragments in the time range of 100 ns to 200 mu s. Results: New isomers and prompt and delayed transitions were established in the even-A Sb122-131 isotopes. In the odd-A Sb122-131 isotopes, new prompt and delayed gamma-ray transitions were identified, in addition to the confirmation of the previously known isomers. The half-lives of the isomeric states and the B(E2) transition probabilities of the observed transitions depopulating these isomers were extracted. Conclusions: The experimental data was compared with the theoretical results obtained in the framework of large-scale shell-model (LSSM) calculations in a restricted model space. Modifications of several components of the shell-model interaction were introduced to obtain a consistent agreement with the excitation energies and the B(E2) transition probabilities in neutron-rich Sn and Sb isotopes. The isomeric configurations in Sn and Sb were found to be relatively pure. Furthermore, the calculations revealed that the presence of a single valence proton, mainly in the g(7/2) orbital in Sb isotopes, leads to significant mixing (due to the v pi interaction) of (i) the neutron seniorities (upsilon(v)) and (ii) the neutron angular momentum (I-v). The above features have a weak impact on the excitation energies, but have an important impact on the B(E2) transition probabilities. In addition, a constancy of the relative excitation energies irrespective of neutron seniority and neutron number in Sn and Sb was observed.
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| 8. |
- Clement, E., et al.
(author)
-
Spectroscopic quadrupole moments in 124Xe
- 2023
-
In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 107:1
-
Journal article (peer-reviewed)abstract
- Background: The Xe isotopic chain with four valence protons above the Z = 50 shell closure is an ideal laboratory for the study of the evolution of nuclear deformation. At the N = 82 shell closure, 136Xe presents all characteristics of a doubly closed shell nucleus with a spherical shape. In the very neutron-deficient isotopes close to N = 50, the alpha-decay chain of Xe was investigated to probe the radioactive decay properties near the drip-line and the magicity of 100Sn. Additionally, the Xe isotopes present higher order symmetries in the nuclear deformation such as the octupole degree of freedom near N = 60 and N = 90 or O(6) symmetry in stable isotopes.Purpose: The relevance of the O(6) symmetry has been investigated by measuring the spectroscopic quadrupole moment of the first excited states in 124Xe. In the O(6) symmetry limit, the spectroscopic quadrupole moment of collective states is expected to be null.Method: A stable 124Xe beam with energies of 4.03A MeV and 4.11A MeV was used to bombard a natW target at the GANIL facility. Excited states were populated via the safe Coulomb excitation reaction. The collision of the heavy ions with a large Z at low energy make this reaction sensitive to the diagonal E2 matrix element of the excited states. The recoils were detected in the VAMOS++ magnetic spectrometer and the gamma rays in the AGATA tracking array. The least squares fitting code GOSIA was used for the analysis to extract both E2 and M1 transitional and E2 diagonal matrix elements.Results: The rotational ground state band was populated up to the 8+1 state as well as the 2+2 and 4+2 states. Using high precision spectroscopic data to constrain the GOSIA fit, the spectroscopic quadrupole moments of the 2+1 , 4+1 , and 6+1 states were determined for the first time.Conclusions: The spectroscopic quadrupole moments were found to be negative, large, and constant in the ground state band underlining the prolate axially deformed ground state band of 124Xe. The present experimental data confirm that the is broken in 124Xe.
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| 9. |
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| 10. |
- Mineva, AN, et al.
(author)
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A new mu s isomer in Sb-136 produced in the projectile fission of U-238
- 2001
-
In: EUROPEAN PHYSICAL JOURNAL A. - : SPRINGER-VERLAG. - 1434-6001. ; 11:1, s. 9-13
-
Journal article (peer-reviewed)abstract
- The neutron-rich isotope Sb-136 has been produced following the relativistic projectile fission of U-238 in an experiment performed at the Fragment Separator at GSI, Darmstadt. Delayed gamma -ray spectroscopy of the fission products has been performed aft
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| 11. |
- Mineva, Milena, et al.
(author)
-
A New us Isomer in 136Sb Produced in the Projectile Fission of 238U
- 2001
-
In: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 11, s. 9-13
-
Journal article (peer-reviewed)abstract
- The neutron-rich isotope Sb-136 has been produced following the relativistic projectile fission of U-238 in an experiment performed at the Fragment Separator at GSI, Darmstadt. Delayed gamma -ray spectroscopy of the fission products has been performed after isotope separation. A new isomeric state in Sb-136 has been populated, and its lifetime measured as T-1/2 = 565(50) ns. Realistic and empirical shell-model calculations have been performed and are compared to the experimental observables.
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| 12. |
- Ralet, D., et al.
(author)
-
Evidence of octupole-phonons at high spin in Pb-207
- 2019
-
In: Physics Letters B. - : ELSEVIER. - 0370-2693 .- 1873-2445. ; 797
-
Journal article (peer-reviewed)abstract
- A lifetime measurement of the 19/2(-) state in Pb-207 has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a Pb-208 beam impinging on a Mo-100 enriched target. The beam-like nuclei were detected and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt gamma rays were detected by the AGATA tracking array. The measured large reduced transition probability B(E3, 19/2(-) -> 13/2(+)) = 40(8) W.u. is the first indication of the octupole phonon at high spin in Pb-207. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in Pb-207 is compatible with the contributions from single-phonon and single particle E3 as well as E3 strength arising from the double-octupole-phonon 6(+) state, all adding coherently. A crucial aspect of the coupling model, namely the strong mixing between single-hole and the phonon-hole states, is confirmed in a realistic shell-model calculation. Crown Copyright (C) 2019 Published by Elsevier B.V.
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| 13. |
- Siciliano, M., et al.
(author)
-
STUDY OF QUADRUPOLE CORRELATIONS IN N = Z=5 0 REGION VIA LIFETIME MEASUREMENTS
- 2017
-
In: Acta Physica Polonica B. - : Jagiellonian University Press. - 0587-4254 .- 1509-5770. ; 48:3, s. 331-336
-
Journal article (peer-reviewed)abstract
- During the AGATA campaign at GANIL, the neutron-deficient Sn region was populated via a multi-nucleon transfer reaction in order to directly measure the lifetime of the first excited states with a plunger device, providing complementary information to previous results obtained with Coulomb excitation experiments. The AGATA gamma-ray array was used together with the VAMOS++ spectrometer to study the nuclei of interest.
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| 14. |
- Mantovani, G., et al.
(author)
-
Study of High-Energy Fission in Inverse Kinematics
- 2019
-
In: IV INTERNATIONAL CONFERENCE ON NUCLEAR STRUCTURE AND DYNAMICS (NSD2019). - : EDP Sciences. - 2100-014X. - 9782759890842 ; 223
-
Conference paper (peer-reviewed)abstract
- Fission at low excitation energy, is a process in which both macroscopic and microscopic aspects are involved. Some features in the total kinetic energy and in the N/Z distributions of the fragments, commonly associated with shell effects, came out in a series of recent experiments with high excitation energy fusion fission reactions in inverse kinematics. In the latest experiment of this campaign, a study of high-energy fission and quasi-fission between a U-238 beam and a series of light targets was carried out by using the aforementioned technique, in order to probe the role of the shell structure in these processes.
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| 15. |
- Podolyak, Z, et al.
(author)
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Isomer spectroscopy of neutron rich W-190(116)
- 2000
-
In: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 491:3-4, s. 225-231
-
Journal article (other academic/artistic)abstract
- Gamma-rays de-exciting a millisecond isomer in the neutron-rich nucleus W-190(74)116 have been observed following relativistic projectile fragmentation of a I GeV per nucleon Pb-208 beam. Th, isomeric decay populates the ground-state rotational band, with
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| 16. |
- Fernandez, D., et al.
(author)
-
Experimental study of high-energy fission and quasi-fission dynamics with fusion-induced fission reactions at VAMOS(++)
- 2023
-
In: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - 2100-014X. ; 284
-
Conference paper (peer-reviewed)abstract
- During the last decade, the use of inverse kinematics in the experimental study of fission is bringing a wealth of new observables obtained in single measurements, allowing their analysis and their correlations. An ongoing application of this technique is the basis of a series of experiments performed with the variable -mode, large -acceptance VAMOS++ spectrometer at GANIL. A recent experiment has been focused on the survival of the nuclear structure effects at high excitation energy in fission and quasi-fission. The full isotopic identification of fragments, the fission dynamics and the ratio between the production of fragments with even and odd atomic numbers, the so-called proton even -odd effect, are shown. The latter shows a different mechanism for fission and quasi -fission that could be used to separate fission from quasi-fission.
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| 17. |
- Le Gentil, E., et al.
(author)
-
Coincidence measurement of residues and light particles in the reaction Fe-56+p at 1 GeV per nucleon with the spallation reactions setup SPALADIN
- 2008
-
In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 100:2
-
Journal article (peer-reviewed)abstract
- The spallation of Fe-56 in collisions with hydrogen at 1A GeV has been studied in inverse kinematics with the large-aperture setup SPALADIN at GSI. Coincidences of residues with low-center-of-mass kinetic energy light particles and fragments have been measured allowing the decomposition of the total reaction cross section into the different possible deexcitation channels. Detailed information on the evolution of these deexcitation channels with excitation energy has also been obtained. The comparison of the data with predictions of several deexcitation models coupled to the INCL4 intranuclear cascade model shows that only GEMINI can reasonably account for the bulk of collected results, indicating that in a light system with no compression and little angular momentum, multifragmentation might not be necessary to explain the data.
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| 18. |
- Ramos, D., et al.
(author)
-
Dependence of Fission-Fragment Properties On Excitation Energy For Neutron-Rich Actinides
- 2016
-
In: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759819706 ; 111
-
Conference paper (peer-reviewed)abstract
- Experimental access to full isotopic fragment distributions is very important to determine the features of the fission process. However, the isotopic identification of fission fragments has been, in the past, partial and scarce. A solution based on the use of inverse kinematics to study transfer-induced fission of exotic actinides was carried out at GANIL, resulting in the first experiment accessing the full identification of a collection of fissioning systems and their corresponding fission fragment distribution. In these experiments, a U-238 beam at 6.14 AMeV impinged on a carbon target to produce fissioning systems from U to Am by transfer reactions, and Cf by fusion reactions. Isotopic fission yields of Cf-250, Cm-244, Pu-240, Np-239 and U-238 are presented in this work. With this information, the average number of neutrons as a function of the atomic number of the fragments is calculated, which reflects the impact of nuclear structure around Z=50, N=80 on the production of fission fragments. The characteristics of the Super Long, Standard I, Standard II, and Standard III fission channels were extracted from fits of the fragment yields for different ranges of excitation energy. The position and contribution of the fission channels as function of excitation energy are presented.
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| 19. |
- Ramos, D., et al.
(author)
-
Experimental evidence of the effect of nuclear shells on fission dissipation and time
- 2023
-
In: Physical Review C. - 2469-9985 .- 2469-9993. ; 107:2
-
Journal article (peer-reviewed)abstract
- Nuclear fission is still one of the most complex physical processes we can observe in nature due to the interplay of macroscopic and microscopic nuclear properties that decide the result. An example of this coupling is the presence of nuclear dissipation as an important ingredient that contributes to drive the dynamics and has a clear impact on the time of the process. However, different theoretical interpretations, and scarce experimental data make it poorly understood. In this Letter, we present the first experimental determination of the dissipation energy in fission as a function of the fragment split, for three different fissioning systems. The amount of dissipation was obtained through the measurement of the relative production of fragments with even and odd atomic numbers with respect to different initial fission energies. The results reveal a clear effect of particular nuclear shells on the dissipation and fission dynamics. In addition, the relative production of fragments with even and odd atomic numbers appears as a potential contributor to the long-standing problem of the time scale in fission.
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| 20. |
- Ramos, D., et al.
(author)
-
First Direct Measurement of Isotopic Fission-Fragment Yields of 239U
- 2019
-
In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 123:9
-
Journal article (peer-reviewed)abstract
- A direct and complete measurement of isotopic fission-fragment yields of U-239 has been performed for the first time. The U-239 fissioning system was produced with an average excitation energy of 8.3 MeV in one-neutron transfer reactions between a U-239 beam and a Be-9 target at Coulomb barrier energies. The fission fragments were detected and isotopically identified using the VAMOS++ spectrometer at the GANIL facility. The measurement allows us to directly evaluate the fission models at excitation energies of fast neutrons, which are 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 U-239, and they confirm the persistence of spherical shell effects in the Sn region at excitation energies exceeding the fission barrier by a few mega-electron volts.
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| 21. |
- Ramos, D., et al.
(author)
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Fission Yields of Minor Actinides at Low Energy Through Multi-nucleon Transfer Reactions of 238U on 12C
- 2015
-
In: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 46:3, s. 443-446
-
Journal article (peer-reviewed)abstract
- First preliminary results of fragments distribution as a function of the excitation energy for different fissioning systems from U to Cm and Cf-250 are presented. A new method based on inverse kinematics to study transfer-induced fission of minor actinides was carried out in GANIL in 2008, and again in 2011. In these experiments, a U-238 beam at 6.1 A MeV impinged on a carbon target to produce fissioning systems by multi-nucleon transfer reactions, resulting in the first experiments accessing the full identification of a collection of fissioning systems and their corresponding fission fragments distribution. The excitation energy is deduced from the detection of the recoil nucleus in an angular DE-E stripped silicon telescope, and the identification of the fragments is made possible by the VAMOS spectrometer.
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| 22. |
- Ramos, D., et al.
(author)
-
Insight into excitation energy and structure effects in fission from isotopic information in fission yields
- 2019
-
In: Physical Review C. - 2469-9985 .- 2469-9993. ; 99:2
-
Journal article (peer-reviewed)abstract
- The use of the inverse kinematics technique and a magnetic spectrometer permits the simultaneous measurement of proton and neutron content of full fission fragment distributions. This paper reports new measurements of five fissioning systems - U238,Np239,Pu240,Cm244, and Cf250 - produced in inelastic scattering, transfer, and fusion reactions at different excitation energies. As a result, isotopic, elemental, and isotonic fission yields are presented. The contribution of the different fission modes and the proton even-odd effect are studied. Structure effects are investigated by means of the neutron excess and the total neutron multiplicity as a function of the fragment atomic number.
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| 23. |
- Ramos, D., et al.
(author)
-
Isotopic fission-fragment distributions of U-238, Np-239, Pu-240, Cm-244, and Cf-250 produced through inelastic scattering, transfer, and fusion reactions in inverse kinematics
- 2018
-
In: Physical Review C. - 2469-9985 .- 2469-9993. ; 97:5
-
Journal article (peer-reviewed)abstract
- Transfer- and fusion-induced fission in inverse kinematics has proved to be a powerful tool to investigate nuclear fission, widening information on the fission fragments and access to unstable fissioning systems with respect to other experimental approaches. An experimental campaign is being carried out at GANIL with this technique since 2008. In these experiments, a beam of U-238, accelerated to 6.1 MeV/u, impinges on a C-12 target. Fissioning systems from U to Cf are populated through inelastic scattering, transfer, and fusion reactions, with excitation energies that range from a few MeV up to 46 MeV. The use of inverse kinematics, the SPIDER telescope, and the VAMOS spectrometer allow the characterization of the fissioning system in terms of mass, nuclear charge, and excitation energy, and the isotopic identification of the full fragment distribution. This work reports on new data from the second experiment of the campaign on fission-fragment yields of the heavy actinides U-238, Np-239, Pu-240, Cm-244, and Cf-250, which are of interest from both fundamental and application points of view.
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| 24. |
- Ramos, D., et al.
(author)
-
Scission configuration of U-239 from yields and kinetic information of fission fragments
- 2020
-
In: Physical Review C. - 2469-9985 .- 2469-9993. ; 101:3
-
Journal article (peer-reviewed)abstract
- The simultaneous measurement of the isotopic fission-fragment yields and fission-fragment velocities of U-239 has been performed for the first time. The U-239 fissioning system was produced in one-neutron transfer reactions between a U-238 beam at 5.88 MeV/nucleon and a Be-9 target. The combination of inverse kinematics at low energy and the use of the VAMOS + + spectrometer at the GANIL facility allows the isotopic identification of the full fission-fragment distribution and their velocity in the reference frame of the fissioning system. The proton and neutron content of the fragments at scission, their total kinetic and total excitation energy, as well as the neutron multiplicity were determined. Information from the scission point configuration is obtained from these observables and the correlation between them. The role of the octupole-deformed proton and neutron shells in the fission-fragment production is discussed.
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| 25. |
- Schubart, R, et al.
(author)
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In-beam spectroscopy and shell model structure of the neutron deficient In-103 and CD-100,CD-102
- 1995
-
In: Physica Scripta. - : ROYAL SWEDISH ACAD SCIENCES. - 0031-8949 .- 1402-4896. ; T56, s. 311-315
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Journal article (peer-reviewed)abstract
- The ?-decay of the neutron deficient nuclei 103In and 100,102Cd has been studied following the reactions 58Ni + 50Cr and 58Ni + 46,48Ti at 250 MeV and 230 MeV bombarding energy of the 58Ni beam, respectively. Evaporation neutrons and charged particles were measured in coincidence with prompt and delayed ?-rays with the multidetector array OSIRIS. To investigate the decay of the I? = 8+ isomers of 100,102Cd a recoil catcher setup inside OSIRIS was used. Six new ?-ray transitions of 100Cd and four of 102Cd with intensities of 1-10% of the main ?-ray cascades were found. Two new states of 100Cd were established and firm spin-parity assignments were made to all states below the isomer. These new states were identified as the 4+ and the 6+ members of the proton ?g9/2?2 multiplet. The experimental states of 103In and of 100,102Cd are compared to shell model predictions in the ?(p1/2, g9/2) v(d5/2, g7/2, s1/2, d3/2, h11/2) configuration space.
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