1. Systematic study of Z = 83 nuclei: 193,194,195Bi
Andrej Herzáň
SSNET’17 Conference, CNRS, Gif-sur-Yvette
November 6-10, 2017

2. First identified as an individual element
in 1753 by Claude-Francois Geoffroy.

3. Motivation Evolution of deformation and shape coexistence
High-spin isomeric states
Collective structures on top of the isomeric states
Magnetic rotation bands
Superdeformed bands
web-docs.gsi.de

4. Experimental setup & methodology
JUROGAM II HPGe array + RITU gas-filled separator + GREAT focal plane spectrometer (MWPC, DSSD, PIN diodes, Planar Ge strip detector, clover-type HPGe detectors)
Fusion-evaporation reactions (thin & thick target data)
TDR experiments
Recoil-gating, Recoil-decay tagging and Isomer tagging techniques
DCO and IPDCO analyses
152 MeV
190 MeV
176 MeV

5. Previous & recent studies
First measurement of excited states in 195Bi: (29/2-) isomer
194Bi 𝛼-decay data:
3+, 7+ and 10- isomers
The (29/2-) isomer observed in 193Bi
Sign of collectivity & new high-spin isomer in 195Bi
Laser spectroscopy data available for 194Bi
1986
1991
2004
2015
2017 T
193Bi: P. Nieminen et al., Phys. Rev. C 69, (2004)
194Bi: P. Van Duppen et al., Nucl. Phys. A 529, 268 (1991); A.E. Barzakh et al., Phys. Rev. C 95, (2017)
195Bi: T. Lönnroth et al., Phys. Rev. C 33, (1986); T. Roy et al., Eur. Phys. J. A 51, 153 (2015)
A. Herzáň et al., Phys. Rev. C 92, (2015)
A. Herzáň et al., Phys. Rev. C 96, (2017)
A. Herzáň et al., to be published

6. High-spin isomeric states in odd-A Bi nuclei
𝜋i13/2(h9/2)2
Properties
Decay
Feeding

7. Decay of the high-spin isomeric states
193Bi
Decay of the high-spin isomeric states
195Bi

9. Feeding of the 29/2- isomeric state

10. Feeding of the 29/2+ isomeric states
πi13/2 ν(i13/2)2
Mixing of the 31/2+ states
V = 1.3 keV
𝚫Ep = 5 keV
𝚫Eu = 4.27 keV
193Bi
πi13/2(h9/2)2
V = 1.1 keV
𝚫Ep = 3 keV
𝚫Eu = 2.03 keV
195Bi
πi13/2

11. Superdeformation “Identical” SD bands in 191,193,195Bi
Configuration: πi11/21/2+[651] orbital, (α = -1/2)
Possible linking transition in 193Bi
½+ proton intruder state
alpha-tagged JuroGam II spectrum
M. Nyman et al., EPJ A 51, 31 (2015).
S. Bouneau et al., PR C 58, 3260 (1998).

12. Structure of 194Bi
The only doubly-odd Bi isotope with known strongly coupled rotational bands
Strongly coupled bands associated with 𝜋h9/2 / 𝜋i13/2 ⊗ 𝜈(i13/2)-1 configurations
(11+) isomeric state – to this date only observed in 194Bi isotope
Moderate oblate quadrupole deformation assigned to both bands

13. Magnetic rotation bands
3(?) shears bands in 194Bi
B4 in 194Bi: πi13/2 ⊗ ν(i13/2)-2 (p3/2)-1 configuration, Ibh = (17-)
Shears bands in 198Bi – 4 and 6 quasiparticle configurations:
a. πh9/2 ⊗ ν(i13/2)-2 (p3/2f5/2)-3
b. πh9/2 ⊗ ν(i13/2)-3
nucalf.physics.fsu.edu
MR band also observed in 195Bi:
feeding the (29/2-) isomeric state: a counterpart of a shears band in 194Pb;
Ibh = (35/2-) at Ex = 3595 keV;
𝜋(h9/22i13/2) ⊗ 𝜈(i13/2p3/2)-2 5-qp configuration.

14. Summary Extensive level schemes for both odd-A Bi isotopes
Onset of collectivity extends to 195Bi – a transitional nucleus
Exp. evidence for smaller quadrupole deformations in 195Bi than in 193Bi
New high-spin isomeric states found in all three Bi isotopes
Superdeformed bands identified in 193,195Bi nuclei
Excited states on top of the isomeric alpha-decaying isomeric states in 194Bi observed for the first time
Magnetic rotation bands observed in 194Bi and 195Bi
New configurations explained mainly on the basis of particle-core coupling scheme
Nuclear theory for very heavy nuclei is very much needed!
Experiment proposal to study the structures just discussed also in 191,192Bi approved by the JYFL PAC