Published May 1981 | Version v1
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Contribution of the study of neutron-proton coupling modes in transition nuclei: high-spin and low-spin states of 140Pm and 186Au

Description

The excited levels of the 140Pm and 186Au odd-odd transitional nuclei have been studied by means of two complementary methods: the low-spin states populated by the β++CE decay of 140Sm and 186Hg respectively, the high-spin states by (19F,5nγ) reactions. The radioactive sources have been produced at the on-line mass-separator Isocele: γ-γ and γ-X coincidence spectra have been measured; conversion electrons were detected with Si(Li) detector working with a magnetic selector (140Pm) or with a semi-circular spectograph (186Au). The high-spin level schemes were deduced from γ-γ coincidence analysis, spins and parities from angular distribution, linear polarization and DCO measurements. The low- and high-spin states are interpreted in terms of the one quasiparticle states which appear in the adjacent odd-A nuclei. Concerning low-spin states, the coupling of two-quasiparticle angular momenta are qualitatively discussed. The hihg-spin state energies are compared to those calculated within an ''asymmetric rotor + two high-j qp'' coupling schemes

Availability note (English)

MF available from INIS under the Report Number.

Abstract (French)

Les niveaux excites de deux noyaux impairs-impairs de transition 140Pm et 186Au on ete etudies par des methodes complementaires: etats de bas spin peuples par des desintegration β++CE (140Sm → Pm et 186Hg → Au) et etats de haut spin peuples par reaction (19F,5nγ). Les mesures concernant les etats de bas spin ont ete effectuees aupres du separateur en ligne Isocele: coincidence γ-γ et γ-X, electrons de conversion detectes soit a l'aide d'un detecteur Si(Li) associe a un selecteur magnetique (140Pm), soit d'un spectrographe magnetique a 1800(186Au). Les schemas de niveaux de haut spin ont ete construits a partir des relations de coincidences γ-γ: les spins et parites des niveaux ont ete determines grace a des mesures de distributions angulaires, polarisations lineaires et correlations angulaires directionnelles des rayonnements γ les desexcitant. Les niveaux de bas spin et de haut spin ainsi obtenu ont ete interpretes a partir des etats a une quasi-particule presents dans les noyaux impairs voisins. Dans le premier cas, le couplage des moments angulaires des deux quasi-particules a ete discute qualitativement; les energies des etats de haut spin on ete compares aux resultats d'un modele de couplage d'un rotor asymetrique et de deux quasipaticules situees dans des sous-couches de grand J

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Additional titles

Original title (French)
Contribution a l'etude des modes de couplage neutron-proton dans les noyaux de transition: etats excites de haut spin et de bas spin de

Publishing Information

Imprint Pagination
170p.
Report number
CSNSM-T--81-01