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Author |
Gjestvang, D. et al; Algora, A. |
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Title |
Examination of how properties of a fissioning system impact isomeric yield ratios of the fragments |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
108 |
Issue |
6 |
Pages |
064602 - 12pp |
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Keywords |
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Abstract |
The population of isomeric states in the prompt decay of fission fragments-so-called isomeric yield ratios (IYRs)-is known to be sensitive to the angular momentum J that the fragment emerged with, and may therefore contain valuable information on the mechanism behind the fission process. In this work, we investigate how changes in the fissioning system impact the measured IYRs of fission fragments to learn more about what parameters affect angular momentum generation. To enable this, a new technique for measuring IYRs is first demonstrated. It is based on the time of arrival of discrete gamma rays, and has the advantage that it enables the study of the IYR as a function of properties of the partner nucleus. This technique is used to extract the IYR of 134Te, strongly populated in actinide fission, from the three different fissioning systems: 232Th(n, f), 238U(n, f), at two different neutron energies, as well as 252Cf(sf). The impacts of changing the fissioning system, the compound nuclear excitation energy, the minimum J of the binary partner, and the number of neutrons emitted on the IYR of 134Te are determined. The decay code TALYS is used in combination with the fission simulation code FREYA to calculate the primary fragment angular momentum from the IYR. We find that the IYR of 134Te has a slope of 0.004 +/- 0.002 with increase in compound nucleus (CN) mass. When investigating the impact on the IYR of increased CN excitation energy, we find no change with an energy increase similar to the difference between thermal and fast fission. By varying the mass of the partner fragment emerging with 134Te, it is revealed that the IYR of 134Te is independent of the total amount of prompt neutrons emitted from the fragment pair. This indicates that neutrons carry minimal angular momentum away from the fission fragments. Comparisons with the FREYA+TALYS simulations reveal that the average angular momentum in 134Te following 238U(n, f) is 6.0 h over bar . This is not consistent with the value deduced from recent CGMF calculations. Finally, the IYR sensitivity to the angular momentum of the primary fragment is discussed. These results are not only important to help understanding the underlying mechanism in nuclear fission, but can also be used to constrain and benchmark fission models, and are relevant to the gamma -ray heating problem of reactors. |
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Address |
[Gjestvang, D.; Siem, S.; Nemer, J.; Paulsen, W.; Popovitch, Y.] Univ Oslo, Dept Phys, N-0316 Oslo, Norway, Email: dorthea.gjestvang@fys.uio.no |
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Amer Physical Soc |
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English |
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ISSN |
2469-9985 |
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Conference |
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Notes |
WOS:001160674400006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5947 |
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Author |
Yue, Z. et al; Algora, A.; Nacher, E. |
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Title |
Magnetic moments of thallium isotopes in the vicinity of magic N=126 |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
849 |
Issue |
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Pages |
138452 - 7pp |
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Keywords |
Laser spectroscopy; Hyperfine structure; Magnetic dipole moments; Theory of finite Fermi systems |
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Abstract |
The magnetic dipole moments (mu) of Tl-209(g)(N =128) and Tl-207(m)(N = 126) have been measured for the first time using the in -source laser resonance -ionization spectroscopy technique with the Laser Ion Source and Trap (LIST) at ISOLDE (CERN). The application of the LIST suppresses the usually overwhelming background of the isobaric francium isotopes and allows access to heavy thallium isotopes with >207. The self -consistent theory of finite Fermi systems based on the energy density functional by Fayans et al. well describes the N dependence of μfor 1/2(+) thallium ground states, as well as μfor the 11/2(-) isomeric states in europium, gold and thallium isotopes. The inclusion of particle-vibration coupling leads to a better agreement between the theory and experiment for mu(Tl-g , I-pi = 1/2(+)). It is shown that beyond mean-field contributions tocannot be neglected at least for thallium isotopes with I-pi = 1/2(+). |
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[Yue, Z.; Andreyev, A. N.; Cubiss, J. G.] Univ York, Sch Phys Engn & Technol, York YO10 5DD, England, Email: zixuan.yue@cern.ch |
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Elsevier |
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English |
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ISSN |
0370-2693 |
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Conference |
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Notes |
WOS:001180137800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5979 |
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Author |
Guadilla, V.; Algora, A.; Estienne, M.; Fallot, M.; Gelletly, W.; Porta, A.; Rigalleau, L.M.; Stutzmann, J.S. |
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Title |
First measurements with a new fl-electron detector for spectral shape studies |
Type |
Journal Article |
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Year |
2024 |
Publication |
Journal of Instrumentation |
Abbreviated Journal |
J. Instrum. |
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Volume |
19 |
Issue |
2 |
Pages |
P02027 - 21pp |
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Keywords |
Detector modelling and simulations I (interaction of radiation with matter; interaction of photons with matter; interaction of hadrons with matter; etc); Instrumentation for radioactive beams (fragmentation devices; fragment and isotope; separators incl. ISOL; isobar separators; ion and atom traps; weak-beam diagnostics; radioactive-beam ion sources); Hybrid detectors; Spectrometers |
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Abstract |
The shape of the electron spectrum emitted in /3 decay carries a wealth of information about nuclear structure and fundamental physics. In spite of that, few dedicated measurements have been made of /3 -spectrum shapes. In this work we present a newly developed detector for /3 electrons based on a telescope concept. A thick plastic scintillator is employed in coincidence with a thin silicon detector. The first measurements employing this detector have been carried out with mono -energetic electrons from the high-energy resolution electron -beam spectrometer at Bordeaux. Here we report on the good reproduction of the experimental spectra of mono -energetic electrons using Monte Carlo simulations. This is a crucial step for future experiments, where a detailed Monte Carlo characterization of the detector is needed to determine the shape of the /3 -electron spectra by deconvolution of the measured spectra with the response function of the detector. A chamber to contain two telescope assemblies has been designed for future /3 -decay experiments at the Ion Guide Isotope Separator On -Line facility in Jyvaskyla, aimed at improving our understanding of reactor antineutrino spectra. |
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Address |
[Guadilla, V.; Estienne, M.; Fallot, M.; Porta, A.; Rigalleau, L. -m.; Stutzmann, J. -s.] Univ Nantes, Subatech, IMT Atlantique, CNRS,IN2P3, F-44307 Nantes, France, Email: vguadilla@fuw.edu.pl |
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Publisher |
IOP Publishing Ltd |
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English |
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Series Issue |
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Edition |
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ISSN |
1748-0221 |
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Notes |
WOS:001181748300007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6064 |
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Author |
Jungclaus, A.; Doornenbal, P.; Acosta, J.; Vaquero, V.; Browne, F.; Cortes, M.L.; Gargano, A.; Koiwai, T.; Naidja, H.; Taniuchi, R.; Tostevin, J.A.; Wimmer, K.; Algora, A.; Baba, H.; Fernandez, A.; Lalovic, N.; Nacher, E.; Rubio, B.; Sakurai, H. |
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Title |
Position of the single-particle 3/2- state in 135Sn and the N = 90 subshell closure |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
851 |
Issue |
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Pages |
138561 - 5pp |
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Keywords |
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Abstract |
The decay of excited states of the nucleus Sn-135, with three neutrons outside the doubly-magic Sn-132 core, was studied in an experiment performed at the Radioactive Isotope Beam Factory at RIKEN. Several gamma rays emitted from excited Sn-135 ions were observed following one-neutron and one-neutron-one-proton removal from Sn-136 and Sb-137 beams, respectively, on a beryllium target at relativistic energies. Based on the analogy to 133Sn populated via one-neutron removal from Sn-134, an excitation energy of 695(15) keV is assigned to the 3/2(-) state with strongest single-particle character in 135Sn. This result provides the first direct information about the evolution of the neutron shell structure beyond N = 82 and thus allows for a crucial test of shellmodel calculations in this region. The experimental findings are in full agreement with calculations performed employing microscopic effective two-body interactions derived from CD-Bonn and N3LO nucleon-nucleon potentials, which do not predict a pronounced subshell gap at neutron number N=90. The occurrence of such a gap in Sn-140, i.e., when the 1f(7/2) orbital is completely filled, had been proposed in the past, in analogy to the magicity of Ca-48, featuring a completely filled 0f(7/2) orbital one harmonic oscillator shell below. |
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Address |
[Jungclaus, A.; Acosta, J.; Vaquero, V.; Fernandez, A.] CSIC, Inst Estruct Mat, E-28006 Madrid, Spain, Email: andrea.jungclaus@csic.es |
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Publisher |
Elsevier |
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English |
Summary Language |
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Series Volume |
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ISSN |
0370-2693 |
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Conference |
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Notes |
WOS:001208129000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6114 |
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Author |
Das, B. et al; Algora, A. |
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Title |
Broken seniority symmetry in the semimagic proton mid-shell nucleus 95Rh |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physical Review Research |
Abbreviated Journal |
Phys. Rev. Res. |
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Volume |
6 |
Issue |
2 |
Pages |
L022038 - 7pp |
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Keywords |
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Abstract |
Lifetime measurements of low-lying excited states in the semimagic ( N = 50) nucleus 95 Rh have been performed by means of the fast -timing technique. The experiment was carried out using gamma -ray detector arrays consisting of LaBr 3 (Ce) scintillators and germanium detectors integrated into the DESPEC experimental setup commissioned for the Facility for Antiproton and Ion Research ( FAIR ) Phase -0, Darmstadt, Germany. The excited states in 95 Rh were populated primarily via the /3 decays of 95 Pd nuclei, produced in the projectile fragmentation of a 850 MeV / nucleon 124 Xe beam impinging on a 4 g / cm 2 9 Be target. The deduced electromagnetic E2 transition strengths for the gamma -ray cascade within the multiplet structure depopulating from the isomeric I pi = 21 / 2 + state are found to exhibit strong deviations from predictions of standard shell model calculations which feature approximately conserved seniority symmetry. In particular, the observation of a strongly suppressed E2 strength for the 13 / 2 + -> 9 / 2 + ground state transition cannot be explained by calculations employing standard interactions. This remarkable result may require revision of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations, and might also point to the need for including three-body forces in the Hamiltonian. |
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Address |
[Das, B.; Cederwall, B.; Qi, C.; Aktas, O.; Liotta, R.; Vasiljevic, J.] KTH Royal Inst Technol, S-10691 Stockholm, Sweden, Email: b.das@gsi.de; |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Notes |
WOS:001240855200002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6147 |
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