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Author |
n_TOF Collaboration (Moreno-Soto, J. et al); Babiano-Suarez, V.; Caballero-Ontanaya, L.; Domingo-Pardo, C.; Ladarescu, I.; Tain, J.L. |
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Title |
Constraints on the dipole photon strength for the odd uranium isotopes |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
105 |
Issue |
2 |
Pages |
024618 - 14pp |
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Keywords |
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Abstract |
Background: The photon strength functions (PSFs) and nuclear level density (NLD) are key ingredients for calculation of the photon interaction with nuclei, in particular the reaction cross sections. These cross sections are important especially in nuclear astrophysics and in the development of advanced nuclear technologies. Purpose: The role of the scissors mode in the M1 PSF of (well-deformed) actinides was investigated by several experimental techniques. The analyses of different experiments result in significant differences, especially on the strength of the mode. The shape of the low-energy tail of the giant electric dipole resonance is uncertain as well. In particular, some works proposed a presence of the E1 pygmy resonance just above 7 MeV. Because of these inconsistencies additional information on PSFs in this region is of great interest. Methods: The gamma-ray spectra from neutron-capture reactions on the U-234, U-236, and U-238 nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated s-wave resonances up to about 140 eV. Results: The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions and nuclear level density. No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) E1 PSF, which match the experimental spectra as well as the total radiative widths. Conclusions: The constant temperature energy dependence is favored for a NLD. The tail of giant electric dipole resonance is well described by the MGLO model of the E1 PSF with no hint of pygmy resonance. The M1 PSF must contain a very strong, relatively wide, and likely double-resonance scissors mode. The mode is responsible for about a half of the total radiative width of neutron resonances and significantly affects the radiative cross section. |
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Address |
[Moreno-Soto, J.; Berthoumieux, E.; Dupont, E.; Gunsing, F.; Bacak, M.] Univ Paris Saclay, CEA Irfu, F-91191 Gif Sur Yvette, France, Email: jmoreno53@us.es; |
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Publisher |
Amer Physical Soc |
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English |
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Series Volume |
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Series Issue |
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ISSN |
2469-9985 |
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Conference |
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Notes |
WOS:000810791100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number  |
IFIC @ pastor @ |
Serial |
5278 |
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Author |
n_TOF Collaboration (Mastromarco, M. et al); Domingo-Pardo, C.; Tain, J.L. |
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Title |
High accuracy, high resolution U-235(n,f) cross section from n_TOF (CERN) from 18 meV to 10 keV |
Type |
Journal Article |
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Year |
2022 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
58 |
Issue |
8 |
Pages |
147 - 13pp |
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Abstract |
The U-235(n,f) cross section was measured in a wide energy range (18 meV-170 keV) at the nTOF facility at CERN, relative to Li-6(n,t) and B-10(n,alpha) standard reactions, with high resolution and accuracy, with a setup based on a stack of six samples and six silicon detectors placed in the neutron beam. In this paper we report on the results in the region between 18 meV and 10 keV neutron energy. A resonance analysis has been performed up to 200 eV, with the code SAMMY. The resulting fission kernels are compared with the ones extracted on the basis of the resonance parameters of the most recent major evaluated data libraries. A comparison of the nTOF data with the evaluated cross sections is also performed from thermal to 10 keV neutron energy for the energy-averaged cross section in energy groups of suitably chosen width. A good agreement, within 0.5%, is found on average between the new results and the latest evaluated data files ENDF/B-VIII.0 and JEFF-3.3, as well as with respect to the broad group average fission cross section established in the framework of the standard working group of IAEA (the so-called reference file). However, some discrepancies, of up to 4%, are still present in some specific energy regions. The new dataset here presented, characterized by a unique combination of high resolution and accuracy, low background and wide energy range, can help to improve the evaluations from the Resolved Resonance Region up to 10 keV, also reducing the uncertainties that affect this region. |
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Address |
[Mastromarco, M.; Colonna, N.; Diacono, D.] Ist Nazl Fis Nucl, Sez Bari, Bari, Italy, Email: amaducci@lns.infn.it |
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Springer |
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English |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6001 |
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Conference |
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Notes |
WOS:000840312100002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5328 |
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Author |
Kiss, G.G. et al; Tarifeño-Saldivia, A.; Tain, J.L.; Agramunt, J.; Algora, A.; Domingo-Pardo, C.; Morales, A.I.; Nacher, E.; Rubio, B.; Tolosa, A. |
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Title |
Measuring the beta-decay Properties of Neutron-rich Exotic Pm, Sm, Eu, and Gd Isotopes to Constrain the Nucleosynthesis Yields in the Rare-earth Region |
Type |
Journal Article |
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Year |
2022 |
Publication |
Astrophysical Journal |
Abbreviated Journal |
Astrophys. J. |
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Volume |
936 |
Issue |
2 |
Pages |
107 - 18pp |
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Keywords |
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Abstract |
The beta-delayed neutron-emission probabilities of 28 exotic neutron-rich isotopes of Pm, Sm, Eu, and Gd were measured for the first time at RIKEN Nishina Center using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The existing beta-decay half-life (T (1/2)) database was significantly increased toward more neutron-rich isotopes, and uncertainties for previously measured values were decreased. The new data not only constrain the theoretical predictions of half-lives and beta-delayed neutron-emission probabilities, but also allow for probing the mechanisms of formation of the high-mass wing of the rare-earth peak located at A approximate to 160 in the r-process abundance distribution through astrophysical reaction network calculations. An uncertainty quantification of the calculated abundance patterns with the new data shows a reduction of the uncertainty in the rare-earth peak region. The newly introduced variance-based sensitivity analysis method offers valuable insight into the influence of important nuclear physics inputs on the calculated abundance patterns. The analysis has identified the half-lives of Sm-168 and of several gadolinium isotopes as some of the key variables among the current experimental data to understand the remaining abundance uncertainty at A = 167-172. |
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Address |
[Kiss, G. G.; Vitez-Sveiczer, A.; Algora, A.; Szegedi, T. N.] Inst Nucl Res ATOMKI, Bem Ter 18-c, H-4026 Debrecen, Hungary, Email: ggkiss@atomki.hu; |
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Publisher |
IOP Publishing Ltd |
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English |
Summary Language |
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ISSN |
0004-637x |
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Notes |
WOS:000850804600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5353 |
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Author |
AGATA Collaboration (Liu, X. et al); Gadea, A.; Jurado, M.; Domingo-Pardo, C.; Huyuk, T.; Perez-Vidal, R.M. |
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Title |
Evidence for spherical-oblate shape coexistence in Tc-87 |
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 |
3 |
Pages |
034304 - 6pp |
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Keywords |
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Abstract |
Excited states in the neutron-deficient nucleus Tc-87 have been studied via the fusion-evaporation reaction 54Fe(36Ar, 2n1p) Tc-87 at 115 MeV beam energy. The AGATA gamma-ray spectrometer coupled to the DIAMANT, NEDA, and Neutron Wall detector arrays for light-particle detection was used to measure the prompt coincidence of gamma rays and light particles. Six transitions from the deexcitation of excited states belonging to a new band in Tc-87 were identified by comparing gamma-ray intensities in the spectra gated under different reaction channel selection conditions. The constructed level structure was compared with the shell model and total Routhian surface calculations. The results indicate that the new band structure in 87Tc is built on a spherical configuration, which is different from that assigned to the previously identified oblate yrast rotational band. |
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Address |
[Liu, X.; Cederwall, B.; Qi, C.; Wyss, R. A.; Aktas, O.; Ertoprak, A.; Zhang, W.; Nyberg, A. Atac; Back, T.] Royal Inst Technol, Dept Phys, S-10405 Stockholm, Sweden, Email: xiaoyuli@kth.se |
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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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Conference |
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Notes |
WOS:000863087400003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5373 |
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Author |
Perez-Vidal, R.M. et al; Gadea, A.; Jurado, M.; Domingo-Pardo, C.; Huyuk, T. |
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Title |
Evidence of Partial Seniority Conservation in the pi g9/2 Shell for the N=50 Isotones |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
129 |
Issue |
11 |
Pages |
112501 - 7pp |
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Keywords |
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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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Address |
[Perez-Vidal, R. M.; Gadea, A.; Domingo-Pardo, C.; Huyuk, T.] Univ Valencia, Inst Fis Corpuscular, CSIC, E-46980 Valencia, Spain, Email: perezvidal@lnl.infn.it |
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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 |
0031-9007 |
ISBN |
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Notes |
WOS:000861160200004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5374 |
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