| 131. |
- Weiszflog, M., et al.
(författare)
-
High-spin spectroscopy of Ga-63(31)32 and Ga-65(31)34
- 2001
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 11:1, s. 25-38
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states in the nuclei Ga-63 and Ga-65 were studied following the reaction S-32 + Ca-40 at a reaction energy of 125 MeV and using the GASP gamma -ray spectrometer in combination with the ISIS charged-particle detector system. In addition to low-lying negative-parity states with single-particle character, rotational-like cascades built on the 9/2(+) and 19/2(-) states have been observed in both nuclei. Sidebands with negative parity in Ga-63 and positive parity in Ga-65 could be established. The experimental results are compared with Total Routhian Surface calculations which describe the nuclei as moderately deformed (beta (2) approximate to 0.25) and gamma soft at low rotational frequencies. The highest experimentally observed positive-parity state in Ga-65 (41/2(+)) is in good agreement with the calculated crossing of the collective band with a non-collective one terminating at this spin.
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| 132. |
- Axelsson, A, et al.
(författare)
-
Excited superdeformed band in Eu-143
- 1999
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 6:2, s. 175-183
-
Tidskriftsartikel (refereegranskat)abstract
- A new superdeformed band has been discovered in a EUROBALL experiment and assigned to Eu-143. It has a maximum intensity of 35% of the Eu-143 yrast superdeformed band and the transition energies of the two bands are very similar. Based on comparison with cranked shell model calculations the new band is tentatively assigned the high-N intruder configuration pi 6(2)nu 7(0) and the parity and signature quantum numbers (pi, alpha) = (-1, +1/2). In addition to the already known high-energy transition at 3361 keV another discrete line at 2715 keV was found to be in coincidence with the yrast superdeformed band. However, it was not possible to connect the decay out of either of the superdeformed bands to, known normally deformed states.
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| 133. |
- Boso, A., et al.
(författare)
-
ISOSPIN SYMMETRY BREAKING IN MIRROR NUCLEI Mg-23-Na-23
- 2017
-
Ingår i: Acta Physica Polonica B. - : Jagiellonian University Press. - 0587-4254 .- 1509-5770. ; 48:3, s. 313-318
-
Tidskriftsartikel (refereegranskat)abstract
- Mirror energy differences (MED) are a direct consequence of isospin symmetry breaking. Moreover, the study of MED has proved to give valuable information of several nuclear structure properties. We present the results of an experiment performed in GANIL to study the MED in mirror nuclei Mg-23-Na-23 up to high spin. The experimental values are compared with state-of-the-art shell model calculations. This permits to enlighten several nuclear structure properties, such as the way in which the nucleons alignment proceeds, the radius variation with J, the role of the spin-orbit interaction and the importance of isospin symmetry breaking terms of nuclear origin.
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| 134. |
- Boso, A., et al.
(författare)
-
Neutron Skin Effects in Mirror Energy Differences : The Case of Mg-23-Na-23
- 2018
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 121:3
-
Tidskriftsartikel (refereegranskat)abstract
- Energy differences between analogue states in the T = 1/2 Mg-23-Na-23 mirror nuclei have been measured along the rotational yrast bands. This allows us to search for effects arising from isospin-symmetrybreaking interactions (ISB) and/or shape changes. Data are interpreted in the shell model framework following the method successfully applied to nuclei in the f(7/2) shell. It is shown that the introduction of a schematic ISB interaction of the same type of that used in the f(7/2) shell is needed to reproduce the data. An alternative novel description, applied here for the first time, relies on the use of an effective interaction deduced from a realistic charge-dependent chiral nucleon-nucleon potential. This analysis provides two important results: (i) The mirror energy differences give direct insight into the nuclear skin; (ii) the skin changes along the rotational bands are strongly correlated with the difference between the neutron and proton occupations of the s(1/2) "halo" orbit.
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| 135. |
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| 136. |
- Fitzgerald, M., et al.
(författare)
-
Toroidal Alfven eigenmode stability in JET internal transport barrier afterglow experiments
- 2022
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:10
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we use reduced and perturbative models to examine the stability of toroidal Alfven eigenmodes (TAEs) during the internal transport barrier (ITB) afterglow in JET experiments designed for the observation of alpha driven TAEs. We demonstrate that in JET-like conditions, it is sufficient to use an incompressible cold plasma model for the TAE to reproduce the experimental adiabatic features such as frequency and position. When ion cyclotron resonant heating (ICRH) is used to destabilize TAEs, the core-localised modes that are predicted to be most strongly driven by minority ICRH fast ions correspond to the modes observed in the DD experiments, and conversely, modes that are predicted to not be driven are not observed. Linear damping rates due to a variety of mechanisms acting during the afterglow are calculated, with important contributions coming from the neutral beam and radiative damping. For DT equivalent extrapolations of discharges without ICRH heating, we find that for the majority of modes, alpha drive is not sufficient to overcome radiative damping.
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| 137. |
- Gadea, A., et al.
(författare)
-
Spectroscopy at N=Z with EUROBALL III
- 1999
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 495, s. 195-198
-
Konferensbidrag (refereegranskat)abstract
- A complete study of the nuclear structure by means of gamma spectroscopy requires, in addition to the high resolution gamma measurement and accurate DCO's or angular distributions, the information concerning the Electric or Magnetic character of the transition. This information for transitions in nuclei far from stability valley is now reachable in the new generation of Ge-arrays based in composite detectors. EUROBALL III is a good example with the high polarization sensitivity of the 90 degrees ring of Clovers. The Polarization correlations PCO's measured in coincidence with the Cluster detectors permits to investigate transitions in weakly populated nuclei. In this contribution we present results on medium mass N=Z nuclei measured with EUROBALL III coupled with light particle ancillary detectors.
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| 138. |
- Hagen, T. W., et al.
(författare)
-
Evolution of nuclear shapes in odd-mass yttrium and niobium isotopes from lifetime measurements following fission reactions
- 2017
-
Ingår i: Physical Review C: covering nuclear physics. - 2469-9985. ; 95:3
-
Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of excited states in Y99,Y101,Nb101,Nb103, and Nb105 were measured in an experiment using the recoil distance Doppler shift method at GANIL (Grand Accélérateur National d'Ions Lourds). The neutron-rich nuclei were produced in fission reactions between a U238 beam and a Be9 target. Prompt γ rays were measured with the EXOGAM array and correlated with fission fragments that were identified in mass and atomic number with the VAMOS++ spectrometer. The measured lifetimes, together with branching ratios, provide B(M1) and B(E2) values for the strongly coupled rotational bands built on the [422]5/2+ ground state in the Y and Nb nuclei with neutron number N≥60. The comparison of the experimental results with triaxial particle-rotor calculations provides information about the evolution of the nuclear shape in this mass region.
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| 139. |
- Weiszflog, M., et al.
(författare)
-
High-spin Spectroscopy of 63Ga and 65Ga
- 2001
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 11, s. 25-38
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states in the nuclei Ga-63 and Ga-65 were studied following the reaction S-32 + Ca-40 at a reaction energy of 125 MeV and using the GASP gamma -ray spectrometer in combination with the ISIS charged-particle detector system. In addition to low-lying negative-parity states with single-particle character, rotational-like cascades built on the 9/2(+) and 19/2(-) states have been observed in both nuclei. Sidebands with negative parity in Ga-63 and positive parity in Ga-65 could be established. The experimental results are compared with Total Routhian Surface calculations which describe the nuclei as moderately deformed (beta (2) approximate to 0.25) and gamma soft at low rotational frequencies. The highest experimentally observed positive-parity state in Ga-65 (41/2(+)) is in good agreement with the calculated crossing of the collective band with a non-collective one terminating at this spin.
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| 140. |
- Axelsson, A, et al.
(författare)
-
Excited superdeformed band in Eu-143
- 1999
-
Ingår i: EUROPEAN PHYSICAL JOURNAL A. - : SPRINGER VERLAG. - 1434-6001. ; 6:2, s. 175-183
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A new superdeformed band has been discovered in a EUROBALL experiment and assigned to Eu-143. It has a maximum intensity of 35% of the Eu-143 yrast superdeformed band and the transition energies of the two bands are very similar. Based on comparison with
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