| 1. |
- Jentschel, M., et al.
(författare)
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EXILL - a high-efficiency, high-resolution setup for gamma-spectroscopy at an intense cold neutron beam facility
- 2017
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- In the EXILL campaign a highly efficient array of high purity germanium (HPGe) detectors was operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of gamma-rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 10(8) ns(-1)cm(2) at the target position and negligible neutron halo. The targetwas surrounded by an array of eight to ten anti-Compton shielded EXOGAMClover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr3:(Ce) detectors from the FATIMA collaboration. The detectorswere arranged in an array of rhombicuboctahedron geometry, providing the possibility to carry out very precise angular correlation and directional-polarization correlation measurements. The triggerless acquisition system allowed a signal collection rate of up to 6 x 10(5) Hz. The data allowed to set multi-fold coincidences to obtain decay schemes and in combination with the FATIMA array of LaBr3:(Ce) detectors to analyze half-lives of excited levels in the pico-to microsecond range. Precise energy and efficiency calibrations of EXILL were performed using standard calibration sources of Ba-133, Co-60 and Eu-152 as well as data from the reactions Al-27(n, gamma)Al-28 and Cl-35(n,gamma)Cl-36 in the energy range from 30 keV up to 10MeV.
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| 2. |
- Leguillon, R., et al.
(författare)
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High-spin spectroscopy of Nd-140
- 2013
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 88:1
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Tidskriftsartikel (refereegranskat)abstract
- The population of the high-spin states in Nd-140 was investigated using the reaction Zr-96(Ca-48,4n). The results from two experiments, one with the EUROBALL array and one with the JUROGAM II + RITU + GREAT setup employing the recoil decay tagging technique, have been combined to develop a very detailed level scheme for Nd-140. Twelve bands of quadrupole transitions and eleven bands of dipole transitions were identified and their connections to low-lying states were established. Calculations using the cranked Nilsson-Strutinsky and the tilted axis cranking models were used to interpret the observed structures. The overall good agreement between the experimental results and the calculations assuming a triaxial shape of the nucleus strongly support the existence of a stable triaxial shape at high spins in this mass region.
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| 3. |
- Petrache, C. M., et al.
(författare)
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Switch from short-axis to intermediate-axis rotation in Nd-138
- 2013
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 88:5
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Tidskriftsartikel (refereegranskat)abstract
- It is pointed out that the triaxial bands in Nd138-140 and in the Lu/Er nuclei can be understood from the same shell structure effects. Two of the bands in Nd-138, interpreted as signature partners, exhibit a crossing at high spins with a signature splitting which is strongly reduced above the crossing. This behavior is unique among the yrast and close-to-yrast configurations, revealing the mechanism which induces a change of the rotation axis from short to intermediate in the triaxially deformed nucleus.
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| 4. |
- Petrache, C. M., et al.
(författare)
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Multiple triaxial bands in Nd-138
- 2015
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:2
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Nd-138 were investigated by using the Ca-48 + Zr-94 reaction and gamma-ray coincidences were acquired with the GASP spectrometer. A rich level scheme was developed including 14 new bands of quadrupole transitions at very high spins. Linking transitions connecting 11 high-spin bands to low-energy states have been observed. Calculations based on the cranked Nilsson-Strutinsky formalism have been used to assign configurations to the observed bands. The main result of these calculations is that all 14 bands exhibit a stable triaxial deformation up to the highest observed spins, giving strong support to the existence of a triaxial minimum with normal deformation and positive asymmetry parameter in nuclei with a few holes in the N = 82 shell closure.
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| 5. |
- Zerrouki, T., et al.
(författare)
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Shape evolution and magnetic rotation in Nd-141
- 2015
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 51:4
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Tidskriftsartikel (refereegranskat)abstract
- The high-spin states in Nd-141 were investigated using the Zr-96(Ca-48, 3n) reaction and the EU-ROBALL array. The level scheme has been extended up to an excitation energy of around 16MeV and spin 81/2. Two new bands of dipole transitions and three bands presumably of quadrupole transitions were identified and their connections to low-lying states were established. Cranked Nilsson-Strutinsky and tilted axis cranking calculations are combined in the interpretation of the observed dipole bands. The high-spin bands with assigned quadrupole transitions are interpreted as triaxial bands, while the dipole bands appear in the calculations to exhibit a shape evolution from low-deformation triaxial to spherical shape. They can be classified as magnetic rotation, with transition probabilities that show the characteristic decrease with angular momentum caused by the shears mechanism.
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