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Author |
Vitez-Sveiczer, A. et al; Algora, A.; Morales, A.I.; Rubio, B.; Agramunt, J.; Guadilla, V.; Montaner-Piza, A.; Orrigo, S.E.A. |
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Title |
The beta-decay of Kr-70 into Br-70: Restoration of the pseudo-SU(4) symmetry |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
830 |
Issue |
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Pages |
137123 - 8pp |
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Keywords |
Beta decay of Kr-70; pn pairing; GT strength distribution; Pseudo-SU(4) symmetry; QRPA calculations |
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Abstract |
The beta-decay of the even-even nucleus Kr-70 with Z=N+2, has been investigated at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center using the BigRIPS fragment separator, the ZeroDegree Spectrometer, the WAS3ABI implantation station and the EURICA HPGe cluster array. Fifteen gamma-rays associated with the beta-decay of( 70)Kr into Br-70 have been identified for the first time, defining ten populated states below E-exc=3300 keV. The half-life of Kr-70 was derived with increased precision and found to be t(1/2)=45.19 +/- 0.14 ms. The beta-delayed proton emission probability has also been determined as epsilon(p)=0.545(23)%. An increase in the beta-strength to the yrast 1(+) state in comparison with the heaviest Z=N+2 system studied so far (Ge-62 decay) is observed that may indicate increased np correlations in the T=0 channel. The beta-decay strength deduced from the results is interpreted in terms of the proton-neutron quasiparticle random-phase approximation (pnQRPA) and also with a schematic model that includes isoscalar and isovector pairing in addition to quadrupole deformation. The application of this last model indicates an approximate realization of pseudo-SU(4) symmetry in this system. |
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Address |
[Vitez-Sveiczer, A.; Algora, A.; Morales, A., I; Rubio, B.; Agramunt, J.; Guadilla, V; Montaner-Piza, A.; Orrigo, S. E. A.; Gelletly, W.] Univ Valencia, Inst Fis Corpuscular, CSIC, E-46071 Valencia, Spain, Email: algora@ific.uv.es; |
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Publisher |
Elsevier |
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English |
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ISSN |
0370-2693 |
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Notes |
WOS:000832707200002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5316 |
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Permanent link to this record |
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Author |
Wimmer, K. et al; Algora, A.; Rubio, B. |
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Title |
Shape Changes in the Mirror Nuclei Kr-70 and Se-70 |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
126 |
Issue |
7 |
Pages |
072501 - 6pp |
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Keywords |
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Abstract |
We studied the proton-rich T-z = -1 nucleus Kr-70 through inelastic scattering at intermediate energies in order to extract the reduced transition probability, B(E2; 0+ -> 2+). Comparison with the other members of the A = 70 isospin triplet, Br-70 and Se-70, studied in the same experiment, shows a 3 sigma deviation from the expected linearity of the electromagnetic matrix elements as a function of T-z. At present, no established nuclear structure theory can describe this observed deviation quantitatively. This is the first violation of isospin symmetry at this level observed in the transition matrix elements. A heuristic approach may explain the anomaly by a shape change between the mirror nuclei Kr-70 and Se-70 contrary to the model predictions. |
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Address |
[Wimmer, K.] CSIC, Inst Estruct Mat, E-28006 Madrid, Spain, Email: k.wimmer@csic.es |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
0031-9007 |
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Expedition |
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Conference |
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Notes |
WOS:000619237200006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4715 |
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Permanent link to this record |
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Author |
Wimmer, K. et al; Algora, A.; Rubio, B. |
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Title |
Shape coexistence revealed in the N = Z isotope Kr-72 through inelastic scattering |
Type |
Journal Article |
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Year |
2020 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
56 |
Issue |
6 |
Pages |
159 - 12pp |
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Keywords |
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Abstract |
The N = Z = 36 nucleus Kr-72 has been studied by inelastic scattering at intermediate energies. Two targets, Be-9 and Au-197, were used to extract the nuclear deformation length, delta(N), and the reduced E2 transition probability, B(E2). The previously unknown non-yrast 2(+) and 4(+) states as well as a new candidate for the octupole 3(-) state have been observed in the scattering on the Be target and placed in the level scheme based on gamma – gamma coincidences. The second 2(+) state was also observed in the scattering on the Au target and the B(E2; 2(2)(+) -> 0(1)(+)) value could be determined for the first time. Analyzing the results in terms of a two-band mixing model shows clear evidence for a oblate-prolate shape coexistence and can be explained by a shape change from an oblate ground state to prolate deformed yrast band from the first 2+ state. This interpretation is corroborated by beyond mean field calculations using the Gogny D1S interaction. |
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Address |
[Wimmer, K.; Ando, T.; Koyama, S.; Nagamine, S.; Niikura, M.; Saito, T. Y.; Sakurai, H.; Taniuchi, R.] Univ Tokyo, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan, Email: k.wimmer@csic.es |
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Publisher |
Springer |
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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 |
1434-6001 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000540063900002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4428 |
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Permanent link to this record |
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Author |
Wimmer, K. et al; Algora, A.; Rubio, B. |
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Title |
Discovery of Br-68 in secondary reactions of radioactive beams |
Type |
Journal Article |
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Year |
2019 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
795 |
Issue |
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Pages |
266-270 |
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Keywords |
Radioactive beams; New isotope; Direct reaction |
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Abstract |
The proton-rich isotope Br-68 was discovered in secondary fragmentation reactions of fast radioactive beams. Proton-rich secondary beams of (70,71,72) Kr and Br-70, produced at the RIKEN Nishina Center and identified by the BigRIPS fragment separator, impinged on a secondary Be-9 target. Unambiguous particle identification behind the secondary target was achieved with the ZeroDegree spectrometer. Based on the expected direct production cross sections from neighboring isotopes, the lifetime of the ground or long-lived isomeric state of Br-68 was estimated. The results suggest that secondary fragmentation reactions, where relatively few nucleons are removed from the projectile, offer an alternative way to search for new isotopes, as these reactions populate preferentially low-lying states. |
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Address |
[Wimmer, K.; Ando, T.; Koyama, S.; Nagamine, S.; Niikura, M.; Saito, Ty; Sakurai, H.; Taniuchi, R.] Univ Tokyo, Dept Phys, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan, Email: wimmer@phys.s.u-tokyo.ac.jp |
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Publisher |
Elsevier |
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 |
0370-2693 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000477924000037 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4100 |
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Permanent link to this record |
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Author |
Wimmer, K. et al; Algora, A.; Rubio, B. |
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Title |
Shape coexistence and isospin symmetry in A=70 nuclei: Spectroscopy of the T-z =-1 nucleus Kr-70 |
Type |
Journal Article |
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Year |
2018 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
785 |
Issue |
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Pages |
441-446 |
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Keywords |
Radioactive beams; Gamma-ray spectroscopy; Mirror symmetry; Shape coexistence |
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Abstract |
Excited states in the T-z = -1 nucleus Kr-70 have been populated using inelastic scattering of a radioactive Kr-70 beam as well as one- and two-neutron removal reactions from Kr-71,Kr-72 at intermediate beam energies. The level scheme of Kr-70 was constructed from the observed gamma-ray transitions and coincidences. Tentative spin and parity assignments were made based on comparison with the mirror nucleus Se-70. Asecond 2(+) state and a candidate for the corresponding 4(2)(+) state suggest shape coexistence in Kr-70. |
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Address |
[Wimmer, K.; Ando, T.; Koyama, S.; Nagamine, S.; Niikura, M.; Saito, T. Y.; Sakurai, H.; Taniuchi, R.] Univ Tokyo, Dept Phys, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan, Email: wimmer@phys.s.u-tokyo.ac.jp |
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Publisher |
Elsevier Science Bv |
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 |
0370-2693 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000447424000064 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3795 |
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Permanent link to this record |