10 research outputs found
Evidence for octupole vibration in the triaxial superdeformed well of Lu164
High-spin states in Lu164 were populated in the Sb121(Ca48,5n) reaction at 215 MeV and γ-ray coincidences were measured with the Gammasphere spectrometer. Through this experiment the eight known triaxial superdeformed bands in Lu164 could be confirmed. Some of these bands were extended to higher as well as to lower spins. Evidence is reported for the first time for weak ΔI=1,E1 transitions linking TSD3 and TSD1. This observation may imply coupling to octupole vibrational degrees of freedom. The decay mechanism is different from the one observed in the neighboring even-N isotopes, which exhibit wobbling excitations built on the πi13/2 structure with E2(M1),ΔI=1 interband decay. An additional sequence decaying at high spin into TSD1 was observed up to Iπ=(50-). This band has a constant dynamic moment of inertia of ∼70 2MeV-1 and an alignment that is ∼2 larger than that found for TSD1. A revision of the assumed spin-parity-assignment of TSD2 is based on the observed decay-out to normal-deformed structures. The parity and signature quantum numbers of TSD2 are now firmly assigned as (π,α)=(+,0), in disagreement with the former assignment of (π,α)=(-,1), which was based on the assumption that TSD2 is the signature partner of TSD1. TSD1 and TSD2 show an alignment gain at ω∼0.67 and 0.60 MeV, respectively. In TSD1 the involvement of the j15/2 neutron orbital is suggested to be responsible for the high-frequency crossing
Collective and noncollective excitations in 122Te
High-spin states in 122Te were populated in the reaction 82Se(48Ca, α4n)122Te at a beam energy of 200 MeV and γ-ray coincidences were measured with the Gammasphere spectrometer. The previously known level scheme was extended to considerably higher spin. Maximally aligned states and several high-energy transitions feeding into some of these levels were observed. In addition, seven collective high-spin bands were discovered for the first time in this nucleus. The experimental results are compared with cranked Nilsson-Strutinsky model calculations and possible configuration assignments to the new high-spin structures are discussed
High-spin spectroscopy in Xe125
Levels excited up to 39.8 MeV and 119/2 units of angular momentum have been populated in Xe125 by the 82Se(Ca48,5n)Xe125 reaction. High-fold γ-ray coincidence events were measured using the Gammasphere Ge detector array. Nine regular rotational bands extending from levels identified previously up to almost 60ℏ have been identified, and three of these have been connected to low-lying levels having well-established spins and parities. Configurations have been assigned to six of the bands based on alignment properties, band crossings, and comparison with theoretical cranked shell model calculations (CSM). Transition quadrupole moments have been measured for these bands in the spin range 31-55ℏ and were found to be in agreement with the CSM calculations. The corresponding quadrupole deformation ε2 ranges from 0.28 to 0.34 at a γ deformation of 0° and from 0.29 to 0.36 at a γ value of 5°
Noncollective aligned and antialigned states in I125
High-spin states in I125 were populated using the reaction Se82(Ca48,p4n) at a beam energy of 200 MeV and γ-ray coincidence events were acquired with the Gammasphere spectrometer. The level scheme of I125 was extended considerably. In particular, maximally aligned states involving all eleven particles outside the Sn114 core were observed. Comparison with cranked Nilsson-Strutinsky calculations suggests that three of these states are the final Imax states in terminating bands with all spin vectors aligned along a common axis. In two of these, one spin vector is antialigned and points in the opposite direction. In one of the states two spin vectors are antialigned. This is the first observation of a state with such a structure
Highly deformed high-spin band in 125I
High-spin states in 125I have been investigated using the reaction 82Se(48Ca,p4n) at a beam energy of 200 MeV and γ-ray coincidence events were detected using the Gammasphere spectrometer. A deformed rotational band, extending up to Iπ=95/2-, was observed for the first time in a heavier odd-A iodine nucleus. The characteristics of the band are very similar to those of the highly deformed bands observed recently in neighboring nuclei and it is essentially identical to one of the previously known bands in 126Xe. The experimental results are compared to cranked Nilsson-Strutinsky calculations and possible configurations for the band are discussed
Indication for hyperdeformed cluster states in
An activation technique was used to investigate relative yields of fission products from the reaction 232Th(n, f ) for neutron energies between 1.3 and 1.8MeV covering the region around the first hyperdeformed resonances. Intensities of characteristic γ-ray transitions were analyzed to search for changes in the mass distribution for neutron energies corresponding to the resonances and below the resonances. Relative increases in yield between 7 and 23% are observed for A ≈ 100 and 132 in the resonance region around 1.6MeV. It is proposed that the yield enhancement of daughter nuclei of the preformed fragments 132Sn and 101Zr arises from cold fission of a di-cluster configuration. The experimental results support theoretical predictions for the existence of hyperdeformed octupole shapes based on the di-nuclear configuration 132Sn + 101Zr
Competition between collective and noncollective excitation modes at high spin in 124Ba
High-spin states in 124Ba were investigated in two experiments using the 64Ni(64Ni, 4n)124Ba reaction at three different beam energies. In-beam gamma-ray coincidences were measured with the Euroball and Gammasphere detector arrays. In the experiment with Euroball, the CsI detector array Diamant was employed to discriminate against charged-particle channels. Six new rotational bands were observed in 124Ba, and previously known bands were extended to higher spins. One of the bands shows a transition from collective to noncollective behavior at high spins. Configuration assignments are suggested on the basis of comparison with cranked shell model and cranked Nilsson-Strutinsky calculation