The observation of rotational band�, in different nuclei that have unexpectedly identical moments of inertia and, sometimes, identical y -ray energies has excited the low-energy nuclear physics community recently. These identical bands exist at both low and high spins, and they span a wide variety of shapes that range from weakly oblate, to normal, moderately large, and super-prolate deformations. The pervasive occurrences of identical bands point to the rigidity of the even-even nuclei with respect to the polarization forces of the unpaired valence nucleons.This unexpected stability has posed a serious challenge to theoretical models.

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A rotational band based on the proton hn/ 2 orbital has been observed to high spin (^h) and high rotational frequency (hcu ~ 1.0 MeV) in the nucleus ^f Sb. The measured transition quadrupole moment is QQ = 4.4 ± 0.6 eb, consistent with an axial prolate deformation of $2 -0.32. A large interaction strength (360 ±60 keV) has been measured for the rotational alignment of hn/ 2 neutrons which, together with a considerable delay in the crossing frequency (Ahtu c± 0.09 MeV), is construed as the first direct evidence of a large high-jf proton-neutron interaction.PACS numbers: 21.10. Re, 21.30.+y, 23.20.Lv, 27.60,+j A knowledge of the forces which drive the few-body nuclear system into collective motion, together with an understanding of both collective and noncollective effects within a single unified model, are fundamental goals in the study of nuclear structure. At modest excitation energy and spin in the odd-mass antimony nuclei (Sb, Z = 51), collective band structures are observed to coexist side by side with states corresponding to singleparticle excitations [1,2]. The collective states have been interpreted as proton particle-hole excitations across the major shell gap, made energetically possible by the combination of strong proton-pair correlations and a postulated proton-neutron interaction (e.g., Ref.[3]). The onset of prolate deformation, and thus the appearance of collective rotational bands, has also been linked to the occupation of particular orbitals which are preferentially lowered in energy at large quadrupole deformations (e.g., Ref.[4]), and hence exert a driving force towards increased deformation. Such high-j "intruder" orbitals are characterized by large values of single-particle angular momentum aligned along the axis of rotation, leading to a further reduction in energy due to the Coriolis force at high rotational frequency.Before this study very little experimental information existed concerning states at high spin (7 > 20ft) in nuclei near the Z = 50 closed spherical shell. In addition, no lifetime data (and therefore no measure of the collectivity) existed for the known band structures. In this Letter we address the role of the proton hu/2 orbital as a highspin intruder configuration, and report the first measurement of a transition quadrupole moment for a collective band in the Z = 50 region. Moreover, we show that the observed characteristics of the /in/2 intruder band may now be used to test the standard mean-field approach to nuclear structure calculations.High-spin states in 113 Sb have been populated via the 94 Mo( 23 Na,2p2n) reaction, with a 117-MeV sodium beam provided by the Tandem Accelerator Superconducting Cyclotron (TASCC) Facility at Chalk River Laboratories. Experiments were performed with thin selfsupporting and Au-backed enriched target foils, to provide high energy-resolution data and Doppler-shift information, respectively. Approximately 2 x 10 8 (selfsupporting target) and 3.2 x 10 8 (backed target) 7-7 events were collected with the 8TT spectrometer, which comprises 20...

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AN. (1996). Single step links of the superdeformed band in : A measure of the absolute excitation energy, spin and parity of the superdeformed states. Physics Letters B, 380(1-2), 18-23. https://doi.org/10.1016/0370-2693(96)00367-X Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The EUROGAM array has been used to investigate the decay out of the yrast superdeformed (SD) band in 194pb. Six single step decays from the lowest observed SD states to low-lying states at normal deformation (ND) have been identified. From this observation, the excitation energy of the SD band in 194pb is established at 4877 4-1.5 keV for the 6 + SD state. The most probable spins and parities of all members of the.SD band are also deduced assuming that the SD states have even spin and positive parity.

We have identified yrast states of 152 Dy to spin ~37, with unusually strong population of high-spin states in the ( 32 S,4wy) reaction. Yrast isomers with spins ~17, 21, 27, and 31 were detected. For J ^ 14 the yrast states scatter about a straight line on an E vs IQ +1) plot, consistent with predictions for aligned-p article configurations. The slope of the line yields an effective moment of inertia 18% larger than the rigid-sphere value. This and other arguments suggest possible oblate deformation at high spin.Investigations of high-spin nuclear states, / > 3Qfr, have so far been limited to studies of continuum y radiation. 1 ' 2 Such experiments by their nature provide information only on gross properties of nuclear states over a wide range of excitation energy above the yrast line. Data on the yrast line itself to very high spin will open up a domain of nuclear structure which has hitherto not been explored. In particular one might learn whether there is a general relation between the energies and spins of yrast states, as has been predicted for an independent-particle system, 3 and how shell effects modify this relation; whether dramatic shape changes are induced in nuclei by large angular moments; and how spin is generated with the least expenditure of energy.