L. K. Peker

Evidence for ground and both neutron and proton rotational aligned bands in 68Ge

Abstract From in-beam, γ-ray spectroscopy, the yrast band in 68Ge is found to branch into three positive parity bands at 8+. Bands built on both the yrast 8+ and second 8+ levels show strong backbending in I while the third is apparently a continuation of the ground band. The two lowest 8+ bands provide the first evidence for both proton and neutron rotation-aligned bands built on the same configuration in the one nucleus, here g 9 2 ) 2 . Rotational aligned model calculations confirm these assignments.

Observations of “pairing-free” Kπ = 1+ rotational bands in deformed odd-odd A ∼ 100 nuclei

Abstract Rotational bands with K π = 1 + in the odd-odd nuclei 100,102 39 Y and 102,104 41 Nb are postulated from β − decay of t heir even-even parents. Each two-quasiparticle band has a moment of inertia very close to that of a rigid spheroidal nucleus with deformation β ∼ 0.3, hence these bands are nearly “pairing free”.

On the possible total collapse of the pairing in the isomeric Iπ = 72+ states of odd-A 45Rh and 47Ag nuclei

Abstract In certain three-particle states of odd-A with A ∼ 100−110 and specific [p1p2n1] or [p1n1n2] configurations, the combination of a strong blocking effect and a particularly strong p-n coupling may cause the total collapse of pairing (2Δ → 0). The energy of such a level may sharply drop well below the pairing gap energy to occur near to the ground state. Evidence is presented that the well-known J π = 7 2 + anomalous isomeric states in odd-A 45Rh and 47Ag nuclei with Eexc {[ p 1 ( g 9 2 ) n 1 ( g 7 2 )] 1 + n 2 (r00 5/2 ) .

Particle angular momentum alignment effects in deformed nuclei

Abstract Systematic examinations of the angular momentum generated by particle alignment were made for Dy and Er isotopes. Marked deviations are observed from the aligned spin values expected for full alignment of i 13 2 ( odd A) and ( i 13 2 ) 2 ( even A) particles. Suggested origins of these differences are presented.

Nuclear shapes and the configuration (i132,h92) in A ∼ 150 nuclei

Abstract The level structures of nuclei with A ∼ 150 N = 83−86 have been carefully analyzed to identify how their nuclear shapes change with increasing spin. Levels which include the v(i 13 2 , h 9 2 ) 11- configuration, are found to be the lowest states with significant oblate deformation ( β ≈−0.15) in N =83, 84 nuclei, but are spherical ( β ≈ 0) in N = 86 and possibly N = 85 and prolate ( β ≈ 0.2) in N = 88. All states with I π ⩽ 27 - are spherical in 150 Gd 86 and 152 Dy 86 and presumably other N = 86 nuclei.