Evidence for a rotational band in99Y

Abstract

The nucleus ~Y6~ lies at a transition between spherical and deformed nuclear shapes. Several of its neighbours are known to show rotational properties: The even-even nuclei 98Sr60 and 100Zr~0 seem to be deformed in their ground state [1][2][3] with the coexistence of spherical shapes at small excitation energies [4,5]. In the odd-odd isotope 98y a rotation-like band exists based on an excited state [6 I. Now a search for rotational bands in 99y has been performed. Such bands in an odd proton nucleus would enable the identification of the particular Nilsson orbitals underlying the deformed structure.

Level schemes of100Y and100Zr from the beta-decay of mass separated100Sr

“…[p[~0.1 for the first excited 0+-states in 9~ but which is in accordance to the value [p[=0 23. reported for the 0+-state in the isotone 98Sr[-7].…”

Odd neutron nuclei near A=100: Rotational bands in103Mo and105Mo populated in the? ? decays of103Nb and105Nb

“…The energies of the three lowest levels appear to follow a rotational pattern. This indicates that the situation in these nuclei may be similar to the one in 99y where a well developed rotational ground state band with several members exists [5] but where only the lowest levels are populated in the /~-decay (Pfeiffer et al [25]). First we discuss the lowest energy levels in 1~ and 1~…”

“…Some evidence that rotational bands should be observed comes from studies of the odd proton nuclei. For them a well developed ground state band has been observed recently in 99y [5], even though its underlying even-even core nuclei 98Sr and l~176 seem to have a rather complex structure [6,7]. Some information on the level schemes of 1~ and 1~…”

IBMF and IBFFM Approach to Nuclei in the A≃100 Region

“…There appears the rotational-like band based on the 5/2+ ground state (g.s. ), exhibiting very closely the 1(1+1) energy rule, with members up to 19/2+ [23]. In ref.…”