| 1. |
- Jensen, DR, et al.
(författare)
-
Wobbling phonon excitations, coexisting with normal deformed structures in Lu-163
- 2002
-
Ingår i: Nuclear Physics, Section A. - 0375-9474. ; 703:1-2, s. 3-44
-
Tidskriftsartikel (refereegranskat)abstract
- Wobbling is a rotational mode unique to a triaxial body. The Lu-Hf isotopes with N similar to 94 at high spin provide a possible region of nuclei with pronounced triaxiality. We have investigated Lu-163 through the fusion-evaporation reaction La-139(Si-29,5n)Lu-163 with a beam energy of 152 MeV. Three excited bands decaying into the known, presumably triaxial, superdeformed (TSD) band built on the i(13/2) proton orbital are observed. The electromagnetic properties of the connecting transitions from the two strongest populated excited TSD bands have been investigated. New particle-rotor calculations in which one i(13/2) quasiproton is coupled to the core of triaxial shape produce a variety of bands, whose properties can clearly be interpreted either as "wobbling" or "cranking" motion of the core. Evidence for the assignment of the excited TSD bands as one, and possibly even two wobbling phonon modes built on the yrast TSD band in Lu-163 is given. These triaxial bands coexist with bands built on quasiparticle excitations in the normal deformed (ND) minimum for which new data are also presented.
|
|
| 2. |
- Bark, R A, et al.
(författare)
-
Bandcrossings in Os-171
- 1999
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 646:4, s. 399-413
-
Tidskriftsartikel (refereegranskat)abstract
- The nucleus Os-171 has been populated using the reaction Sn-116(Ni-58,2pn). Four new bands are identified, and the previously known bands are extended in spin, to a maximum of 53/2 (h) over bar. One- and three-quasiparticle configurations are identified, and beta, gamma, and octupole configurations are assigned tentatively. The effects of a possible intruder configuration on the negative parity bands are tested using band-mixing calculations.
|
|
| 3. |
- Bark, R A, et al.
(författare)
-
Coexistence of triaxial and prolate shapes in Ir-171
- 1999
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 657:2, s. 113-133
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states in Ir-171 have been observed for the first time. Gamma-rays were assigned to the nucleus by the recoil-decay tagging method, The ground-state band has a structure consistent with an h(11/2) proton coupled to a core of large triaxial deformation. At high spins, a bandcrossing occurs which is interpreted as a change in shape to a prolate deformation, Band-mixing calculations are performed for Ir171-175. These show that shape-coexistence between triaxial and prolate states in these nuclei follows the same systematics found in their Pt and Os neighbours. The systematics are also compared with deformations calculated for Ir171-179 using the code "Ultimate Cranker". Dipole bands were also observed, but tilted axis cranking calculations suggest that they are associated with a collective rotation.
|
|
| 4. |
- CEDERKALL, J, et al.
(författare)
-
1ST OBSERVATION OF EXCITED-STATES IN SB-108
- 1995
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 581:1, s. 189-204
-
Tidskriftsartikel (refereegranskat)abstract
- A spectroscopic study of Sb-108 has been carried out as a part of a larger experiment where in total twenty-nine different residual nuclei were identified. This study gives the first information on excited levels in this nucleus. A low-lying two-quasi-particle multiplet together with some of the higher lying levels are discussed within the framework of the nuclear shell model. A rotational, strongly coupled, band is identified as, most likely, being built on the deformed pig9/2(-1) nuh11/2 configuration in accordance with total routhian surface calculations. Tentative spins and parities are presented as well as B(M1)/B(E2) ratios for some of the transitions in the strongly coupled band.
|
|
| 5. |
- FAHLANDER, C, et al.
(författare)
-
IN-BEAM SPECTROSCOPY OF TE-110
- 1994
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 577:3-4, s. 773-785
-
Tidskriftsartikel (refereegranskat)abstract
- The neutron-deficient nucleus Te-110 has been investigated by in-beam spectroscopic methods using the NORDBALL multi-detector array. Except for the energy of one level observed in alpha-decay, excited states in Te-110 were previously unknown. The level scheme constructed from gamma gamma-coincidence relationships is presented with tentative spin assignments up to I-pi = 21(-). Above spin 8(+) the yrast states have negative parity. They are most likely the members of a band predominantly based on the nu(h(11/2)g(7/2)) two-quasiparticle configuration. A band crossing is observed at I-pi approximate to 17(-). It is suggested to be caused by the alignment of two h(11/2) neutrons. The cranked shell model correctly predicts the spin alignment, but fails to reproduce the observed band crossing frequency, possibly because of octupole effects.
|
|
| 6. |
- Juutinen, S, et al.
(författare)
-
Coexistence of collective and quasiparticle structures in Sn-106 and Sn-108
- 1997
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 617:1, s. 74-90
-
Tidskriftsartikel (refereegranskat)abstract
- New levels in the neutron deficient nuclei Sn-106 and Sn-108 have been investigated by using the NORDBALL detector array combined with charged particle and neutron detectors. The excited structures are discussed in terms of collectivity and the shell model. The excitations are interpreted to be based on d5/2, g7/2 and h(11/2) both for protons and neutrons and g(9/2) for protons. The systematical behaviour of the specific states in the Sn isotopes is studied in the mass range of A = 106-118.
|
|
| 7. |
- Palacz, M, et al.
(författare)
-
In-beam gamma-ray spectroscopy of Co-56
- 1997
-
Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474 .- 1873-1554. ; 627:1, s. 162-174
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Excited states of Co-56 were studied in the reaction Al-27(S-32,2p1n) Co-56. The NORDBALL array with a Neutron Wall and a Silicon Ball was employed. The excited states were interpreted in terms of particle-hole excitations with respect to the doubly magic
|
|
| 8. |
|
|
| 9. |
- SEWERYNIAK, D, et al.
(författare)
-
IN-BEAM STUDY OF IN-102, IN-104 AND IN-106
- 1995
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 589:1, s. 175-200
-
Tidskriftsartikel (refereegranskat)abstract
- Proton-rich odd-odd In isotopes have been investigated by in-beam spectroscopic methods using the NORDBALL detector array. A Ni-58 beam with an energy of 270 MeV was used to bombard a Fe-54 target. Separation of different reaction channels was achieved with a 4 pi charged-particle multi-detector set-up together with a 1 pi neutron detector wall placed in the forward direction. Excited states of the In-102 nucleus were identified for the first time as well as a set of negative-parity states in In-104. In In-106 the information about positive- and negative-parity states has been extended. The nuclei are discussed within the framework of the nuclear shell model, the interacting boson-fermion-fermion model and the systematics of the heavier odd-odd indium isotopes.
|
|
| 10. |
- TORMANEN, S, et al.
(författare)
-
COMPETING PROTON AND NEUTRON ALIGNMENTS IN NEUTRON-DEFICIENT XE-NUCLEI
- 1994
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 572:2, s. 417-458
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin structures of the neutron-deficient Xe-117, Xe-118, Xe-120 isotopes have been studied by in-beam gamma-ray spectroscopic techniques. The final nuclei have been identified by means of charged-particle detectors. Collective rotational bands based on the neutron d5/2, 97/2 and h11/2 configurations have been identified in Xe-117. In the even Xe-118 and Xe-120 nuclei several new side bands were observed and the previously known bands were extended. The present level schemes include two positive-parity bands constructed to high spin in Xe-118, whereas in Xe-120 three such bands were observed. In order to explain these bands, both proton and neutron (h11/2)2 alignments, as well as the shape degree of freedom, have to be invoked. The possible occurrence of a gammaS-band is addressed and a pronounced structural change for more heavy Xe-isotopes is discussed. All negative-parity side bands are interpreted in terms of proton two-quasiparticle excitations. The experimental data are compared with total routhian surface calculations.
|
|
