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Author |
Ramalho, M.; Suhonen, J.; Kostensalo, J.; Alcala, G.A.; Algora, A.; Fallot, M.; Porta, A.; Zakari-Issoufou, A.A. |
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Title  |
Analysis of the total beta-electron spectrum of( 92)Rb: Implications for the reactor flux anomalies |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
106 |
Issue |
2 |
Pages |
024315 - 7pp |
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Keywords |
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Abstract |
We present here a microscopic nuclear-structure calculation of a beta-electron spectrum including all the beta-decay branches of a high Q-value reactor fission product contributing significantly to the reactor antineutrino energy spectrum. We perform large-scale nuclear shell-model calculations of the total electron spectrum for the beta(-) decay of Rb-92 to states in Sr-92 using a computer cluster. We exploit the beta-branching data of a recent total absorption gamma-ray spectroscopy (TAGS) measurement to determine the effective values of the weak axial-vector coupling, g(A), and the weak axial charge, g(A)(gamma(5)). By using the TAGS data we avoid the bias stemming from the pandemonium effect which is a systematic error biasing the usual beta-decay measurements. We take fully into account all the involved allowed and forbidden beta transitions, in particular the first-forbidden nonunique ones which have earlier been shown to be relevant in the context of the reactor-antineutrino flux anomaly and the unexplained spectral shoulder, the “bump,” the former one having been interpreted as one of the strongest evidence for the existence of sterile neutrinos. Here we are able to present quantitative evidence for the relevance of forbidden nonunique beta(-) decays in a total beta spectrum of a fission product, in this case( 92)Rb, which is one of the major contributors to the total reactor antineutrino spectral shape. We demonstrate that taking the forbidden spectral shapes fully into consideration leads for Rb-92 to a 2.6%-4.6% reduction in the expected inverse beta-decay rate at the reactor antineutrino telescopes. We also confirm by our calculation of a total beta-electron spectrum that the forbidden transitions can contribute to the formation of the spectral bump in the reactor-antineutrino flux profile. |
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Address |
[Ramalho, M.; Suhonen, J.] Univ Jyvaskyla, Dept Phys, POB 35, FI-40014 Jyvaskyla, Finland, Email: madeoliv@jyu.fi; |
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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:000889134200002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5429 |
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Author |
Wilson, J.N. et al; Algora, A. |
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Title |
Angular momentum generation in nuclear fission |
Type |
Journal Article |
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Year |
2021 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
590 |
Issue |
7847 |
Pages |
566-570 |
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Keywords |
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Abstract |
When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning(1); this phenomenon has been a mystery in nuclear physics for over 40 years(2,3). The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum(4-12). Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the gamma-ray heating problem in nuclear reactors(13,14), for the study of the structure of neutron-rich isotopes(15,16), and for the synthesis and stability of super-heavy elements(17,18). gamma-ray spectroscopy experiments on the origin of spin in the products of nuclear fission of spin-zero nuclei suggest that the fission fragments acquire their spin after scission, rather than before. |
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Address |
[Wilson, J. N.; Thisse, D.; Lebois, M.; Jovancevic, N.; Adsley, P.; Babo, M.; Chakma, R.; Delafosse, C.; Haefner, G.; Hauschild, K.; Ibrahim, F.; Ljungvall, J.; Lopez-Martens, A.; Lozeva, R.; Matea, I; Nemer, J.; Popovitch, Y.; Qi, L.; Tocabens, G.; Verney, D.] Univ Paris Saclay, IJC Lab, CNRS, IN2P3, Orsay, France, Email: jonathan.wilson@ijclab.in2p3.fr |
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Publisher |
Nature Research |
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English |
Summary Language |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0028-0836 |
ISBN |
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Notes |
WOS:000621583600006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4717 |
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Author |
Perez-Cerdan, A.B.; Rubio, B.; Gelletly, W.; Algora, A.; Agramunt, J.; Burkard, K.; Huller, W.; Nacher, E.; Sarriguren, P.; Caballero, L.; Molina, F.; Fraile, L.M.; Reillo, E.; Borge, M.J.G.; Dessagne, P.; Jungclaus, A.; Salsac, M.D. |
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Title |
beta decay of (78)Sr |
Type |
Journal Article |
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Year |
2011 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
84 |
Issue |
5 |
Pages |
054311 - 15pp |
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Keywords |
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Abstract |
The gamma rays and conversion electrons emitted in the beta decay of (78)Sr to levels in (78)Rb have been studied using Ge detectors and a mini-orange spectrometer. A reliable level scheme based on the results of these experiments has been established. The properties of the levels in (78)Rb have been compared with calculations based on deformed Hartree-Fock with Skyrme interactions and pairing correlations in the BCS approximation. This has allowed an interpretation of the nature of the observed sets of levels in the odd-odd nucleus (78)Rb. |
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Address |
[Perez-Cerdan, AB; Rubio, B; Algora, A; Agramunt, J; Nacher, E; Caballero, L; Molina, F] Univ Valencia, Inst Fis Corpuscular, CSIC, E-46071 Valencia, Spain, Email: berta.rubio@ific.uv.es |
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Publisher |
Amer Physical Soc |
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Language |
English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0556-2813 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000297122200003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
808 |
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Author |
Orrigo, S.E.A. et al; Rubio, B.; Gelletly, W.; Agramunt, J.; Algora, A.; Molina, F. |
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Title |
beta decay of the exotic T-z =-2 nuclei Fe-48, Ni-52, and Zn-56 |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
93 |
Issue |
4 |
Pages |
044336 - 18pp |
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Keywords |
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Abstract |
The results of a study of the beta decays of three proton-rich nuclei with T-z = -2, namely Fe-48, Ni-52, and Zn-56, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total beta-delayed proton emission branching ratios. We have measured the individual beta-delayed protons and beta-delayed. rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between beta-delayed protons and. rays is observed in the de-excitation of the T = 2 isobaric analog states in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case Zn-56, where the exotic beta-delayed gamma-proton decay has been observed. |
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Address |
[Orrigo, S. E. A.; Rubio, B.; Gelletly, W.; Agramunt, J.; Algora, A.; Molina, F.] Univ Valencia, CSIC, Inst Fis Corpuscular, E-46071 Valencia, Spain, Email: sonja.orrigo@ific.uv.es |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000374955500002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2645 |
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Author |
Orrigo, S.E A. et al; Rubio, B.; Gelletly, W.; Aguilera, P.; Algora, A.; Morales, A.I.; Agramunt, J.; Guadilla, V.; Montaner-Piza, A. |
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Title |
beta decay of the very neutron-deficient Ge-60 and Ge-62 nuclei |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
103 |
Issue |
1 |
Pages |
014324 - 12pp |
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Keywords |
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Abstract |
We report here the results of a study of the beta decay of the proton-rich Ge isotopes, Ge-60 and Ge-62, produced in an experiment at the RIKEN Nishina Center. We have improved our knowledge of the half-lives of Ge-62 [73.5(1) ms] and Ge-60 [25.0(3) ms] and its daughter nucleus, Ga-60 [69.4(2) ms]. We measured individual beta-delayed proton and gamma emissions and their related branching ratios. Decay schemes and absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. A total beta-delayed proton-emission branching ratio of 67(3)% has been obtained for Ge-60. New information has been obtained on the energy levels populated in Ga-60 and on the 1/2(-) excited state in the beta p daughter Zn-59. We extracted a ground state-to-ground state feeding of 85.3(3)% for the decay of Ge-62. Eight new y lines have been added to the deexcitation of levels populated in the Ga-62 daughter. |
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Address |
[Orrigo, S. E. A.; Rubio, B.; Gelletly, W.; Aguilera, P.; Algora, A.; Morales, A., I; Agramunt, J.; Guadilla, V; Montaner-Piza, A.] Univ Valencia, Inst Fis Corpuscular, CSIC, E-46071 Valencia, Spain, Email: sonja.orrigo@ific.uv.es |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000613141500002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4716 |
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