1. 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

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

3. 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

4. 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

5. 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 ?

6. 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, , 2009

7. 186Pb RDT singles conversion-electron spectrum (SAGE) 2+ - 4+ E0 E0
+ E0

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, , 2009

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

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

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

12. → 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

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

14. Qt
│β2│ = 0.28
│β2│ = 0.17

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

16. 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

17. 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.

18. THANK YOU

20. Coexistence vs. mass
Hg isotopes ∆4

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