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

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

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

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 165Ho(32S,4n)193Bi @ 152 MeV 159Tb(40Ar,5n)194Bi @ 190 MeV 159Tb(40Ar,4n)195Bi @ 176 MeV

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, 064326 (2004) 194Bi: P. Van Duppen et al., Nucl. Phys. A 529, 268 (1991); A.E. Barzakh et al., Phys. Rev. C 95, 044324(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, 044310 (2015) A. Herzáň et al., Phys. Rev. C 96, 014301 (2017) A. Herzáň et al., to be published

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

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

Feeding of the 29/2- isomeric state

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

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).

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

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.

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