Two-quasiparticle bands in126Ba

The level scheme of the yrast band of 124Ba has been extended up to spin 32 h. Transitions in the two negative parity side bands are observed up to spin 27 h and tentatively 20h. The second backbend observed in the S-band and the backbends in the side bands are explained as due to neutrons. The structure of the sidebands is discussed and compared with deformation self-consistent calculations, Total Routhian Surfaces (TRS).In this report is presented new data on high spin states in 124Ba. Nuclei in this mass region exhibit structures based on both proton and neutron h11/2 configurations. In the eveneven nuclei a crucial question is to distinguish between proton and neutron configurations. The present data reveM hitherto unobserved crossings at high spin, which might be of help in this context.The nucleus 124Ba was studied by means of 7-7 coincidence data, taken with the ESSA30 array equipped with 30 Comptonsuppressed Ge detectors [1] at the Daresbury Nuclear Structure Facility. The reaction 94Mo(3as,2pn)124Ba was employed at a beam energy of 150 MeV and the relative cross-section for this channel was about 30% of the total cross-section. Part of the decay scheme is shown in fig. 1. The ground band, the S-band and several sidebands were established from previous experiments [2,3]. The present work adds seven more transitions to the S-band, one of which is corrected. The odd-and even-spln negative parity side bands are extended by four and three transitions, respectively. The transitions added reveal crossings in all these bands which we interpret as due to h11/~ neutrons.Additional side bands are also observed in the coincidence data but will not be discussed here.From the l~outhian diagram and the alignment plot ( fig. 2a,b) two different band crossing regions can be distinguished. The ground band is crossed by a two quasi-particle configuration at hw=0.37 MeV_ This crossing has been assigned as due to hm/2 protons [3]. In the uh11/2 band in 123Ba and 12SBa, where the first uh11/2 crossing is blocked, the hit~2 proton crossing is observed at the same frequency [3,4]. The influence of aligned (h11/2)2 configurations on the shape of the nuclei discussed in this note is predicted to he small [5] and blocking arguments may thus be used. In the isotone 123Cs [6] the ~rh11/2 band is crossed by a u(hlI/2) 2 configuration at h~a~0.45 MeV;(the first proton crossing is blocked). Thus there is strong evidence for the crossings observed in 124Ba at heir0.45 MeV being due to h11/2 neutrons.

Section: * Present Address: Price Waterhouse Ltd Ukmentioning

confidence: 71%

High spin spectroscopy of124Ba andh 11/2 neutron alignment

Wyss

Johnson

Love

et al. 1989

“…2(c) and (d). In the bands "3", "4" and "5" crossings are observed at hw ~ 0.4 MeV, which is close to the frequency at which the r or u alignment occurs in the neighbouring odd-even and even-even nuclei [1,2]. In contrast, in the yrast bands, "1" and "2", the first backbending occurs at much higher frequencies.…”

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confidence: 75%

“…In the recent years, extensive studies of nuclear structure have been performed in the mass region A-130 [1,2]. In this region, the nuclear shape is rather soft against V deformation [3,4] and the hlz/2 orbits of both protons and neutrons play a most important role to determine the nuclear shape.…”

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confidence: 99%

High spin structure in the odd-odd nucleus124Cs

Komatsubara

Furuno

Hosoda

et al. 1990

“…Band 13 has no connection to the rest of the level scheme, but we concluded IV[ = 22.9 keV A~= 3.7keV respectively. If we assume that one of these bands has a (nhxl/2) 2 configuration and the other one a (~h11/2) 2 configuration, which is a sensible assumption [3], the mixing matrix element could provide informations on the proton-neutron interaction.…”

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confidence: 99%

High spin states in126Xe

Lieberz

Freund

Granderath

et al. 1988

Self Cite

High spin states of 126Xe have been populated by means of the 116Cd(13C,3n) reaction using the OSIRIS-12 detector system. A level scheme consisting of 13 bands has been established. More than 40 new levels were observed and several spin and parity assignments could be made. Experimental Routhians and alignments of selected bands Recently several Xe-, Ba-and Ce-isotopes have been studied [1][2][3][4][5][6][7] and the observed bands have been interpreted as quasiparticle excitations by using the Cranked Shell model [8]. Schiffer et al. [4] found in t28Ba bandcrossings between the ground state band and two superbands. They observed a strongly coupled negative parity band explained by a neutron h11/2g7/2 configuration and other bands with a more decoupled structure. We expect a similar structure for the isotonic neighbouring nucleus 126Xe. The levels of ~26Xe were investigated via the H6Cd(~aC,3n) reaction at 52, 56 and 60MeV beam energy. An enriched target (97.2%) of 1.Smg/cm 2 lt6Cd on a Bi backing was used. In a coincidence experiment the gammarays were measured with compton suppressed Ge-detectors of the OSIRIS-12 [9] facility. Gamma angular distribution, linear polarization and excitation function measurements were carried out in order to determine spins and parities. All experiments were performed at the FN-Tandem