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An atomic beam magnetic resonance (ABMR) apparatus has been constructed at Orsay, and has been installed at the CERN PS Booster ISOLDE mass separator facility for "on-line" work with radioactive isotopes in a program to measure hyperfine structure anomalies (the Bohr-Weisskopf effect) over long isotopic chains. The hfs anomalies result from the effect of the spatial distribution of the nuclear mag
We have used the 8π γ-ray spectrometer at the Chalk River TASCC facility to study superdeformed rotational bands in the chain of isotopes 145-149Gd. The five bands already known have been extended to higher spin, while four new excited bands have been discovered. The use of very similar reactions, data-acquisition parameters and data-analysis techniques, combined with the enlarged set of data, has
The lifetimes of the three lowest excited members of the rotational ground-state band of103Mo at 102.6, 241.1 and 433.2 keV as well as of the levels at 353.8 and 456.1 keV have been determined through a measurement of the delayed coincidences between β particles from the decay of the parent103Nb and the γ rays which depopulate the levels. A plastic and a BaF2 detector have been used for the β and
The rigid triaxial rotor plus particle model (RTRP) was applied to the nucleus 125Xe in order to determine the value of the γ deformation. Two quantities are very sensitive to the γ deformation: the signature splitting of Yrast levels for negative parity levels (h1 1 2) and the lifetime of the (I= 7 2+, K= 7 2) isomer for positive parity lev els. From the two analyses one obtains the same value fo
High-spin states have been observed in the odd-odd isotope 120Cs in 32S-induced reactions. The previously known band is extended to higher spin and several new bands are identified. Band-head configurations have been inferred by comparing the band properties with known bands in the odd nuclei 121Cs and 121Ba. A remarkable signature inversion is observed in the πh 11 2⊗νh 11 2.
The hyperfine anomaly gives an insight into the coupling of spin and orbital magnetic moments in the nucleus. More precisely, the nuclear magnetization is expressible through the nuclear wave functions with which is tested not only the magnetic moment operator, but also the tensor product [s×C2]1. The experiment can then be expected to be of value in testing the nuclear structure theory. The great
In superdeformed, heavy nuclei at low spins, M1 transitions enhanced by internal conversion are expected to compete favorably with E2 rays. For strongly coupled bands with fairly large B(M1) values, the decay may proceed between the two signature partner bands with very few rays emitted. Measured E2 ray intensities may imply strict limits on the M1 strength. Experimental evidence for the M1 cross
The experimental hindrance factors determined from the fine structure in the C14 decay of Ra223 are strikingly similar to the hindrance factors observed in the alpha decay of odd-A reflection-asymmetric deformed nuclei in spite of the deformed to spherical shape which occurs in the C14 decay. Calculations of the overlap between the reflection-asymmetric ground state of Ra223 and the spherical shel
Excitation energies and branching ratios in 125Xe have been correctly described by using the triaxial rotor plus particle model with deformation parameter ε{lunate}=0.25 and γ=24°. The observed properties, in particular the degeneracy of the yrast favoured and unfavored bands and the signature inversion in the yrare bands are well described by the model. The distribution of core states in the wave
It is shown that the observed transition energies in the superdeformed bands of 148Gd and 146Gd and the two bands of 147Gd are related by a simple linear expression. This is another indication of the remarkable stability of the superdeformed bands and strongly suggests that only two orbitals are active. The relative properties are analysed in terms of the (effective) aligned spin brought in by spe
The yrast band of118Xe has been extended up to tentatively Iπ = 34+ in a heavy-ion in-beam γ-spectroscopic study using the NORDBALL detector array. A band crossing is observed at the highest spins and interpreted within the Modified Oscillator Model as a transition to a terminating band.
We reply to the preceding Comment.
Detailed spectroscopic studies of the discrete γ-rays feeding and deexciting a 41 2-, 4.6 MeV level in 191Hg are reported. The resulting decay scheme indicates single-particle nature for the states above the 41 2- level. At moderate spin, the corresponding particle alignment mode competes favorably with collective oblate rotation. It is suggested that this sequence is associated with a non-collect
We discuss how especially the alignment and the shape polarisation of specific orbitals influence the transition energies in superdeformed bands. The very similar transition energies observed recently in neighbouring nuclei can be qualitatively understood in our approach and the special properties of high-N orbits can be analysed in the same formalism.
Lifetime measurements for the isotopes 155Dy and 156Dy have been extended up to spins around 40h{stroke} by the Doppler shift attenuation method in conjunction with γ-γ-coincidence measurements. Results have been obtained for the yrast band in 156Dy and for three bands in 155Dy. Strong retardations of the E2-strengt were observed for intruding terminating sequences, for which specific single parti
The reanalysis of all the experimental data on 225Ra demonstrates the coexistence of reflection asymmetry and reflection symmetry in this nucleus. In 225Ra as well as 227Ra and 229Th this phenomenon can be explained by the calculated ability of the odd particle in different orbitals to polarise the soft nuclear shapes toward smaller and larger octupole deformations.
The special degeneracy which occurs in the harmonic-oscillator potential when two of the frequencies have ratios of small integer numbers is exploited. Favored shell energies occur for particle numbers which vary with the third frequency. Applications to realistic nuclear potentials show that this degeneracy leads to special shell effects for axial shapes (1:1 ratio) but also for the 2:1 ratio exe
Low-temperature nuclear orientation experiments with isotope separated 228,230pa in an iron host matrix have been performed. From the temperature dependence of the γ-anisotropy in the decay of the isotopes the Larmor frequencies of the ground states have been derived as |VL(228PaFe)| = 552(17) MHz and |vL(230PaFe)| = 475 (13) MHz. Using Bhf(PaFe) = -62.8 (9.0) T the magnetic moments have been dedu
Conventional radio-frequency acceleration form the basis of most accelerators in industry today, and is a scaleable technology used in large-scale research laboratories all over the world. The final particle energy and the availability of the devices are, however, often limited by practical concerns such as price, size, and energy consumption. This prompts research into alternative acceleration me
Multiple superdeformed rotational bands have been identified in a nucleus for the first time. Cascades of 14, 13, and 11 transitions have been assigned to three bands in Dy153. Despite the small intensities, it has been possible to follow the decay of these bands from an angular frequency of 0.7 down to 0.4 MeV/Latin small letter h with stroke. In all three cases, the dynamic moment of inertia scr
