physics.fsu.edu | Experimental Nuclear Physics

COLLECTIVITY IN THE A = 80 REGION OF DEFORMATION

Dr. Samuel L. Tabor

Recent research in the A = 80 region using the John D. Fox Superconducting Accelerator Laboratory has been led by Prof. R.A. Kaye of Ohio Wesleyan University. The largest deformations in the fpg shell occur near the middle (N = Z = 40). The evolution of collectivity in ⁸⁰Y, which lies near mid-shell, was explored by measuring the mean lifetimes using the Doppler-shift attenuation method [1]. Large deformations with transition quadrupole moments Q_t appproaching 4 eb were observed in the yrast negative-parity band at lower spins. Substantial decreases in Q_t with increasing spin are interpreted as resulting from quasiparticle alignments. The magnitude of the decrease is not reproduced well by current models.

Lifetimes were also measured in the isotone ⁷⁹Sr [2]. Very high deformations were also seen, with quadrupole deformations β₂ approaching 0.5, but with less decrease at higher spins. In fact collectivity in the [431] ½⁺ band involving the intruder d_5/2 orbital, the deformation actually increases with increasing spin for the first few states in the band before starting to decrease. This is clearly one of the most deformed nuclei in the A = 80 region with deformations in the so called normal deformed states comparable to those of many superdeformed bands in the region.

References

[1] R.A. Kaye et al., Phys. Rev. C 69, 064314 (2004).
[2] R.A. Kaye et al., Phys. Rev. C 75, 034311 (2007).

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	FSU Experimental Nuclear Physics Main			COLLECTIVITY IN THE A = 80 REGION OF DEFORMATION Dr. Samuel L. Tabor Recent research in the A = 80 region using the John D. Fox Superconducting Accelerator Laboratory has been led by Prof. R.A. Kaye of Ohio Wesleyan University. The largest deformations in the fpg shell occur near the middle (N = Z = 40). The evolution of collectivity in ⁸⁰Y, which lies near mid-shell, was explored by measuring the mean lifetimes using the Doppler-shift attenuation method [1]. Large deformations with transition quadrupole moments Q_t appproaching 4 eb were observed in the yrast negative-parity band at lower spins. Substantial decreases in Q_t with increasing spin are interpreted as resulting from quasiparticle alignments. The magnitude of the decrease is not reproduced well by current models. Lifetimes were also measured in the isotone ⁷⁹Sr [2]. Very high deformations were also seen, with quadrupole deformations β₂ approaching 0.5, but with less decrease at higher spins. In fact collectivity in the [431] ½⁺ band involving the intruder d_5/2 orbital, the deformation actually increases with increasing spin for the first few states in the band before starting to decrease. This is clearly one of the most deformed nuclei in the A = 80 region with deformations in the so called normal deformed states comparable to those of many superdeformed bands in the region. References [1] R.A. Kaye et al., Phys. Rev. C 69, 064314 (2004). [2] R.A. Kaye et al., Phys. Rev. C 75, 034311 (2007). Back to Dr. Tabor's Research Menu