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Author |
Fujita, Y.; Rubio, B.; Gelletly, W. |
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Title |
Spin-isospin excitations probed by strong, weak and electro-magnetic interactions |
Type |
Journal Article |
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Year |
2011 |
Publication |
Progress in Particle and Nuclear Physics |
Abbreviated Journal |
Prog. Part. Nucl. Phys. |
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Volume |
66 |
Issue |
3 |
Pages |
549-606 |
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Keywords |
Gamow-Teller transitions; beta decay; Charge-exchange reactions; Isospin symmetry; High resolution; Proton-rich nuclei |
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Abstract |
Gamow-Teller (GT) transitions are the most common weak interaction processes of spin-isospin (sigma tau) type in atomic nuclei. They are of interest not only in nuclear physics but also in astrophysics; they play an important role in supernovae explosions and nucleosynthesis. The direct study of weak decay processes, however, gives relatively limited information about GT transitions and the states excited via GT transitions (GT states); beta decay can only access states at excitation energies lower than the decay Q-value, and neutrino-induced reactions have very small cross-sections. However, one should note that beta decay has a direct access to the absolute GT transition strengths B(GT) from a study of half-lives, Q(beta)-values and branching ratios. They also provide information on GT transitions in nuclei far-from-stability. Studies of M1 gamma transitions provide similar information. In contrast, the complementary charge-exchange (CE) reactions, such as the (p, n) or ((3)He, t) reactions at intermediate beam energies and 0 degrees, can selectively excite GT states up to high excitation energies in the final nucleus. It has been found empirically that there is a close proportionality between the cross-sections at 0 degrees and the transition strengths B(GT) in these CE reactions. Therefore, CE reactions are useful tools to study the relative values of B(GT) strengths up to high excitation energies. In recent ((3)He, t) measurements, one order-of-magnitude improvement in the energy resolution has been achieved. This has made it possible to make one-to-one comparisons of GT transitions studied in CE reactions and beta decays. Thus GT strengths in ((3)He, t) reactions can be normalised by the beta-decay values. In addition, comparisons with closely related M1 transitions studied in gamma decay or electron inelastic scattering [(e, e')1, and furthermore with “spin” M I transitions that can be studied by proton inelastic scattering [(p, p')[ have now been made possible. In these comparisons, the isospin quantum number T and associated symmetry structure in the same mass A nuclei (isobars) play a key role. Isospin symmetry can extend our scope even to the structures of unstable nuclei that are far from reach at present unstable beam factories. |
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Address |
[Fujita, Y] Osaka Univ, Dept Phys, Osaka 5600043, Japan, Email: fujita@rcnp.osaka-u.ac.jp |
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Elsevier Science Bv |
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English |
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ISSN |
0146-6410 |
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Expedition |
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Conference |
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Notes |
WOS:000292473100003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
692 |
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Author |
Bottoni, S. et al; Gadea, A.; Perez-Vidal, R. M. |
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Title |
Search for the γ decay of the narrow near-threshold proton resonance in 11B |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
855 |
Issue |
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Pages |
138851 - 4pp |
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Keywords |
11B; Near-threshold resonance; gamma-ray decay; Continuum shell model |
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Abstract |
The y decay of the elusive narrow, near-threshold proton resonance in 11 B was investigated at Laboratori Nazionali di Legnaro (INFN) in a particle-y coincidence experiment, using the 6 Li( 6 Li,py) fusion-evaporation reaction and the GALILEO-GALTRACE setup. No clear signature was found for a possible E1 decay to the 1/2-1, – 1 , first-excited state of 11 B, predicted by the Shell Model Embedded in the Continuum (SMEC) with a branching of 0.98+167 +167 -69 x 10-3 -3 with respect to the dominant particle-decaying modes. The statistical analysis of the y-ray spectrum provided an average upper limit of 2.37 x 10-3 -3 for this y-ray branching, with a global significance of 5 sigma. On the other hand, by imposing a global confidence level of 3 sigma, a significant excess of counts was observed for Ey y = 9300(20) keV, corresponding to a resonance energy of 11429(20) keV (namely 200(20) keV above the proton separation energy of 11 B) and a y-ray branching of 1.12(35) x10-3. -3 . This result is compatible with the SMEC calculations, potentially supporting the existence of a near-threshold proton resonance in 11 B. |
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Address |
[Bottoni, S.; Corbari, G.; Leoni, S.; Capra, S.; Albanese, E.; Ziliani, S.; Bracco, A.; Camera, F.; Crespi, F. C. L.; Gamba, E.; Polettini, M.; Porzio, C.] Univ Milano 1, Dipartimento Fis, Via Celoria 16, I-20133 Milan, Italy, Email: simone.bottoni@mi.infn.it |
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Elsevier |
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English |
Summary Language |
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Series Volume |
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Edition |
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ISSN |
0370-2693 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:001272132000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6205 |
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Author |
Yaneva, A. et al; Algora, A. |
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Title |
The shape of the Tz =+1 nucleus 94Pd and the role of proton-neutron interactions on the structure of its excited states |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
855 |
Issue |
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Pages |
138805 - 7pp |
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Keywords |
gamma spectroscopy; Fast-timing gamma-ray coincidences; pn interaction; Isovector vs. isoscalar pairing; Shell model |
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Abstract |
Reduced transition probabilities have been extracted between excited, yrast states in the N = Z + 2 nucleus Pd-94. The transitions of interest were observed following decays of the I-pi = 14(+), E-x = 2129-keV isomeric state, which was populated following the projectile fragmentation of a Xe-124 primary beam at the GSI Helmholtzzentrum fur Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast 8(+) and 6(+) states was determined following isomer-delayed E-gamma 1 – E-gamma 2 – Delta T-2,T-1 coincidence method, using the LaBr3(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in Pd-94 using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8(+) state of 755(106) ps results in a reduced transition probability of B(E2:8(+)-> 6(+)) = 205(-25)(+34) e(2) fm(4), which enables a precise verification of shell-model calculations for this unique system, lying directly between the N = Z line and the N = 50 neutron shell closure. The determined B(E2) value provides an insight into the purity of (g(9/2))(n) configurations in competition with admixtures from excitations between the (lower) N = 3pf and (higher) N = 4gds orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the T = 0 proton-neutron interaction at N = 48. |
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Address |
[Yaneva, A.; Jolie, J.; Armstrong, M.; Blazhev, A.; Esmaylzadeh, A.; Karayonchev, V.; Regis, J. -m.] Univ Cologne, Inst Kernphys, D-50937 Cologne, Germany, Email: a.yaneva@gsi.de |
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Elsevier |
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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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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:001281910600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6221 |
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Author |
Pasqualato, G. et al; Gadea, A.; Jurado, M. |
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Title |
An alternative viewpoint on the nuclear structure towards 100Sn: Lifetime measurements in 105Sn |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
845 |
Issue |
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Pages |
138148 - 7pp |
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Keywords |
Nuclear structure; gamma-ray spectroscopy; Transition probabilities; Neutron-deficient isotopes; Odd-mass nuclei; Lifetime measurements |
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Abstract |
This work aims at presenting an alternative approach to the long standing problem of the B(E2) values in Sn isotopes in the vicinity of the N=Z double-magic nucleus Sn-100, until now predominantly measured with relativistic and intermediate-energy Coulomb excitation reactions. The direct measurement of the lifetime of low-lying excited states in odd-even Sn isotopes provides a new and precise guidance for the theoretical description of the nuclear structure in this region. Lifetime measurements have been performed in Sn-105 for the first time with the coincidence Recoil Distance Doppler Shift technique. The lifetime results for the 7/2(1)(+) first excited state and the 11/2(1)(+) state, 2(+)(Sn-104) circle times nu 1g(7/2) multiplet member, are discussed in comparison with state-of-the-art shell model and mean field calculations, highlighting the crucial contribution of proton excitation across the core of Sn-100. The reduced transition probability B(E2) of the 11/2(1)(+) core-coupled state points out an enhanced staggering with respect to the B(E2; 2(1)(+) -> 0(1)(+)) in the even-mass Sn-104 and Sn-106 isotopes. |
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Address |
[Pasqualato, G.; Mengonia, D.; Goasduff, A.; Lenzi, S. M.; Menegazzo, R.; Montaner-Piza, A.; Recchia, F.; Testov, D.] INFN, Sez Padova, Padua, Italy, Email: giorgia.pasqualato@IJCLAB.IN2P3.FR |
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Publisher |
Elsevier |
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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Expedition |
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Conference |
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Notes |
WOS:001084426400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5725 |
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Author |
Zago, L. et al; Gadea, A.; Algora, A. |
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Title |
High-spin states in Po-212 above the alpha-decaying (18(+)) isomer |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
834 |
Issue |
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Pages |
137457 - 5pp |
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Keywords |
gamma spectroscopy; Isomer spectroscopy; High-spin spectroscopy |
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Abstract |
The nucleus Po-212 has been produced through the fragmentation of a U-238 primary beam at 1GeV/nucleon at GSI, separated with the FRagment Separator, FRS, and studied via isomer gamma-decay spectroscopy with the RISING setup. Two delayed previously unknown gamma rays have been observed. One has been attributed to the E3 decay of a 21(-) isomeric state feeding the alpha-emitting 45-s (18(+)) high-spin isomer. The other gamma-ray line has been assigned to the decay of a higher-lying 23(+) metastable state. These are the first observations of high-spin states above the Po-212 (18(+)) isomer, by virtue of the selectivity obtained via ion-by-ion identification of U-238 fragmentation products. Comparison with shell-model calculations points to shortfalls in the nuclear interactions involving high- jproton and neutron orbitals, to which the region around Z similar to 100 is sensitive. |
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Address |
[Zago, L.; Lunardi, S.; Lenzi, S. M.; Mengoni, D.] Univ Padua, Dipartimento Fis, I-35131 Padua, Italy, Email: luca.zago@lnl.infn.it |
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Thesis |
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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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Expedition |
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Conference |
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Notes |
WOS:000890050000015 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5457 |
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