| 1. |
- Jensen, DR, et al.
(författare)
-
Coexisting wobbling and quasiparticle excitations in the triaxial potential well of Lu-163
- 2004
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 19:2, s. 173-185
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states of the nucleus Lu-163 have been populated through the fusion-evaporation reaction La-139(Si-29, 5n) with a beam energy of 157 MeV. In addition to the two lowest excited triaxial strongly deformed (TSD) bands, recently interpreted as one- and two-phonon wobbling excitations, a third excited TSD band has been firmly established decaying to the yrast TSD band. The assignment of this band as a three-quasiparticle band shows together with the normal deformed (ND) level scheme the presence not only of shape coexistence between ND and TSD structures, but also an interplay of wobbling and quasiparticle excitations in the triaxial strongly deformed potential well of Lu-163.
|
|
| 2. |
- Neusser, A, et al.
(författare)
-
Superdeformed band at very high spin in Nd-140
- 2004
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:6
-
Tidskriftsartikel (refereegranskat)abstract
- A new high-spin superdeformed band has been discovered in Nd-140(60)80. It was populated in the Zr-96(Ca-48,4n) reaction and investigated using the EUROBALL gamma-ray spectrometer array. The band is observed in the approximate spin range of I=36 to 66. It is associated with shell gaps around Z=60 and at N=80 at large deformation. These gaps produce a pronounced minimum in the calculated total Routhian surfaces at a quadrupole deformation of epsilon(2)=0.45. The new band which lies between the high-deformation bands in the Aapproximate to130 region and the superdeformed bands in Aapproximate to150 nuclei provides insight into the development of the deformation between these two regions. Two possible configurations are suggested involving four neutrons of i(13/2) origin (nu6(4)) and either six protons of h(11/2)/h(9/2) origin (pi5(6)) or five protons of h(11/2)/h(9/2) and one of i(13/2) origin (pi5(5)6(1)).
|
|
| 3. |
- Jensen, DR, et al.
(författare)
-
Evidence for second-phonon nuclear wobbling
- 2002
-
Ingår i: Physical Review Letters. - 1079-7114. ; 89:14
-
Tidskriftsartikel (refereegranskat)abstract
- The nucleus Lu-163 has been populated through the reaction La-139(Si-29,5n) with a beam energy of 157 MeV. Three triaxial, strongly deformed (TSD) bands have been observed with very similar rotational properties. The first excited TSD band has earlier been assigned as a one-phonon wobbling excitation built on the lowest-lying (yrast) TSD band. The large B(E2)(out)/B(E2)(in) value obtainable for one of four observed transitions between the second and first excited TSD bands is in good agreement with particle-rotor calculations for a two-phonon wobbling excitation.
|
|
| 4. |
- Schonwasser, G, et al.
(författare)
-
Coexisting normal and triaxial superdeformed structures in Lu-165
- 2004
-
Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 735:3-4, s. 393-424
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Lu-165 were populated in the La-139(Si-30, 4n) reaction at a beam energy of 152 MeV and gamma-ray coincidences were measured with the EUROBALL spectrometer array. Nine new rotational bands were discovered, known band structures were considerably extended and many inter-band transitions were found. Structures with normal deformation coexist with bands associated with the strongly deformed triaxial energy minima found in calculations. Three of these triaxial bands form a family of wobbling excitations with phonon quanta n(w) = 0, 1 and 2. The wobbling mode is a unique signature of nuclear triaxiality. Configuration assignments are discussed for the observed band structures. An exchange of configuration between two of the new bands due to mixing is observed, resulting in different signature partnerships at low and high spins.
|
|
| 5. |
- Schonwasser, G, et al.
(författare)
-
One- and two-phonon wobbling excitations in triaxial Lu-165
- 2003
-
Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 552:1-2, s. 9-16
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Lu-165 have been investigated by in-beam gamma-ray coincidence spectroscopy using the EUROBALL spectrometer array. Two new excited rotational bands have been discovered with features similar to a previously known triaxial superdeformed band in that nucleus. Comparison of the decay pattern of these bands, in particular the unusually large E2 transition strength from the first excited to the yrast superdeformed band, to theoretical calculations shows that they belong to a family of wobbling excitations with phonon numbers n(w) = 0, 1 and 2. These results, together with evidence for nuclear wobbling in the neighbouring isotopes Lu-163 and Lu-167, firmly establish this mode of excitation in the A = 165 mass region. The observation of wobbling is a unique signature of stable nuclear triaxiality. (C) 2002 Elsevier Science B.V. All rights reserved.
|
|
| 6. |
- Wang, S. Y., et al.
(författare)
-
High-spin level scheme of Cs-126
- 2004
-
Ingår i: Gaoneng wuli yu he wuli. - 0254-3052. ; 28:5, s. 491-494
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states of Cs-126 have been populated via the Cd-116(N-14, 4n) Cs-126 reaction. The experiment was performed at Niels Bohr Institute in Denmark in 1991. After careful data analysis, most of the previously-known bands have been pushed up to much higher spins and 3 new rotational sequences have been identified. Spin, parity and configuration assignments are tentatively proposed for all of the observed bands.
|
|
| 7. |
- 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.
|
|
| 8. |
- Schonwasser, G, et al.
(författare)
-
Lifetimes of triaxial superdeformed states in Lu-163 and Lu-164
- 2002
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 13:3, s. 291-296
-
Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of states in the yrast superdeformed bands of Lu-163 and Lu-164 were determined in a Doppler-shift attenuation-method experiment. From fractional Doppler shifts and line shapes, average transition quadrupole moments, Q(t) = 8.2(-0.6)(+1.0) b and 7.1(-0.6)(+0.5) 1), were deduced for one of the bands in Lu-163 OX -0.6 and Lu-164, respectively. These values are much larger than the quadrupole moment of the normal-deformed yrast band in Yb-163, Q(t) = 4.9(-0.4)(+1.34) b, that was also determined in this experiment. Comparison to cranking calculations indicates that both superdeformed bands correspond to a local potential energy minimum with a pronounced triaxiality, gamma similar to 20degrees.
|
|
| 9. |
- Simpson, J., et al.
(författare)
-
Discrete line γ-ray spectroscopy in the (50-60)ℏ spin domain of 161,162Er
- 2000
-
Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:2, s. 243211-243218
-
Tidskriftsartikel (refereegranskat)abstract
- Very high spin states (I=50-60ℏ) have been observed in the transitional nuclei 161Er and 162Er using the Euroball γ-ray spectrometer. In 161Er, three bands are observed well above spin 50ℏ. In the positive parity, positive signature (+, + 1/2) band a discontinuity in the regular rotational behavior occurs at 109/2+ and a splitting into two branches occurs at 97/2- in the negative parity, positive signature (-, + 1/2) band. The ( -, - 1/2) band continues in a regular fashion to 115/2-, tentatively (119/2-). In 162Er the positive parity, even spin (+, 0) yrast band is observed to continue smoothly up to 58+ (60+) and the negative parity, even spin (-,0) and odd spin (-,1) bands are extended from 30- to 34- and from 31- to 47- (49-), respectively. The high spin experimental spectra are compared with both a simple model involving the occupation of specific single neutron states in the absence of neutron pair correlations and with more detailed cranked Nilsson-Strutinsky calculations in which both proton and neutron pairing correlations are neglected. The very high spin domain is found to comprise a series of unpaired rotational bands. Unpaired band crossings between bands with different neutron and proton configurations are identified in 161Er. There is no evidence for aligned oblate or terminating states being close to the yrast line in 161,162Er up to spin ≈60ℏ in contrast to the lighter Er isotopes.
|
|
| 10. |
- Wang, S. Y., et al.
(författare)
-
Structure of the pi g(7/2) 404 7/2(+) band in odd proton nucleus I-123
- 2004
-
Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 21:6, s. 1024-1026
-
Tidskriftsartikel (refereegranskat)abstract
- High spin states of the odd proton nucleus I-123 have been populated in the reaction Cd-116(N-14, 5n2p) at a beam energy of 65 MeV. Two previously known positive-parity DeltaI = 2 sequences have been extended up to 31/2(+) and 41/2(+). In addition, a number of DeltaI = 1 transitions linking the two DeltaI = 2 sequences have been observed. It is suggested that both the DeltaI = 2 sequences are built upon the oblate pi(g) (7/2)[404]7/2(+) Nilsson configuration.
|
|
