of very neutron deficient heavy nuclei In-beam studies of very neutron deficient heavy nuclei Rauno Julin Accelerator Laboratory Department of Physics University of Jyväskylä JYFL Finland

Nuclear spectrocopy is required to understand behaviour of nuclei far from stability can reveal unexpected behaviour of nuclei far from stability

very neutron deficient heavy nuclei Probing neutron-deficient and heavy nuclei with Recoil - Decay - Tagging (RDT) very neutron deficient heavy nuclei  can be produced via fusion evaporation with stable-ion beams and stable targets  cross-sections down to 1 nb  short-living alpha or proton emitters → tagging methods Nb 57 first observations of excited states Pb Sn

Recoil-Decay-Tagging with JUROGAM + RITU + GREAT   Recoil-Decay-Tagging with JUROGAM + RITU + GREAT  , p, β, … e−,  prompt events delayed events Beam Ge array JUROGAM Focal plane Detectors GREAT Separator RITU TDR Total Data Readout

TRIPLE - SHAPE COEXISTENCE Oblate Prolate 186Pb104 Spherical A. Anreyev ... R. Wyss et al. Nature 405, 430 ... but can we identify band structures on top of those ? ... can we see any E0’s ?

EXTREMELY CLEAN SPECTRA RDT γ rays from 186Pb 186Pb 106Pd(83Kr,3n) 186Pb YRAST PROLATE BAND NON-YRAST BAND J. Pakarinen et al. PR C75, 014302, 2009

186Pb RDT singles conversion-electron spectrum (SAGE) 2+ - 4+ E0 0+2 - 0+1 E0 0+3 - 0+1 4+ - 6+ + E0 2+ - 2+ 6+ - 8+ 10+ - 8+

186Pb Above 1MeV 186Pb looks like any deformed nucleus except …… OCTUPOLE PROLATE GAMMA GS. BAND 186Pb OBLATE E0 E0 Above 1MeV 186Pb looks like any deformed nucleus except …… J. Pakarinen et al. PR C75, 014302, 2009

Verification of prolate shape …… 185Pb Coupling of the i13/2 neutron ”hole” to the prolate core Strongly coupled band

Level systematics of even-A Pb nuclei Prolate Spherical N = 104 186Pb 186Pb Oblate

Polonium systematics (Z=84) Energy-level systematics vs. Ground-state radia Oblate Spherical Prolate Understanding of ground-state properties

→ Need B(E2), Qt Moments of Inertia J(1)(rig) = 110 Rigid: Hydrodynamical: J(1) ~ β2 → Need B(E2), Qt PROLATE OBLATE J(1)(rig) = 110

In-beam lifetime measuremets far-from-stability Recoil Distance Doppler-Shift (RDDS) lifetime measurements (plunger). Combined with selective Recoil-Decay-Tagging method.

Qt │β2│ = 0.28 │β2│ = 0.17

Qt/Z for the prolate and oblate bands in midshell Pb,Hg and Pt nuclei Is collectivity really decreasing with decreasing Z ?

Collectivity vs. neutron number: 76Os case even-A Os 168Os: B(E2:4+→2+)/B(E2:2+→0+) < 1 1e2b2 = 173Wu ? 166Os: B(E2:2+→0+) = 7 Wu

2018: Towards lighter neutron-deficient nuclei with MARA RITU MARA MARA is a vacuum-mode recoil separator mainly for proton drip-line studies around N~Z nuclei. MARA is a complementary separator to RITU gas-filled recoil separator. MARA is ideal for studies of nuclei produced with symmetric and inverse reactions. RITU is better for heavier products produced with asymmetric reactions.

THANK YOU

Coexistence vs. mass Hg isotopes ∆4

Verification of prolate shape in 185Pb Coupling of the i13/2 neutron ”hole” to the prolate core Strongly coupled band