1. Perspectives for studies of extremely deformed nuclei near 40Ca
Shapes and Symmetries in Nuclei:
from Experiment to Theory,
Gif-sur-Yvette, November 2017
Piotr Bednarczyk

2. Outline
Theoretical approaches to superdeformation in nuclei below 48Cr (simplistic view)
Link between enlogated (Jacobi) shapes of a CN and large deformation in a cold residuum- exp. indication
Experimental opportunities:
AGATA+PARIS at GANIL
COULEX experiments (worldwide)
Recoil Filter Detector + GALILEO at LNL

3. Collective effects in f7/2 shell nuclei
48Cr is the key nucleus in the Shell Model understanding of nuclear deformation
A,Z ≤24
Caurier et al., PRL 75, 2466 (1995).
Jmax 24
WSU*
48Cr
Spherical shape
at band termination
w [MeV]
* J.Dudek
gap closure at wmax
(fp) 8 (f7/2p3/2f5/2p1/2)- Jmax = 16+

4. Terminating bands near the f7/2 mid-shell
Extra quadrupole polarization by sd hole(s)-fp particles
45Sc
45Sc E1
MeV
𝑱 𝒎𝒂𝒙 = 𝒋 𝒊
Band termination:
The maximum alligned state is oblate (noncollective)
Experimental proof: lifetimes in 45Sc
Collinear laser spectroscopy (m, Qs)
b(t)
d3/2-1f7/26
M Avgoulea et al., JPG 38, (2011)
45mSc Ip=3/2+ (12.4 keV, T1/2=318ms)
P.B. et al., EPJA 20, 45 (2004)

5. Single particle structure of (super)deformation
A,Z ≤24
SD bands
100Sn
N=24 isotones 44Ca, 46Ti ?
80Zr
N=3
particles
58Ni
40Ca
holes
28Si
N=2
b~0.5 b=
40Ca(SD): 8pfp-8hsd
40Ca(SD): 8pfp-8hsd
44Ti(SD): 8pfp-4hsd
H.Ropke , EPJ A 22, 213 (2004)
48Cr - like

6. SD in 40Ca, is it a SM effect ?
In 40Ca the 8p-8h SD band seems NOT to lose the collective character at high spins
Rigid-like rotor ?
SM: fixed 8h-8p sdfp
unrestricted sdfp
experiment
C. J. Chiara et al, Phys.Rev. C 67, (2003)
E. Caurier et al., PRC 75, (2007)

7. „Molecular” (collective ) states close to 40Ca
24Mg+12C SM
a clusters HD
20Ne+16O
28Si+8Be
Binary configurations
b =
28Si+8Be SD
20Ne+16O
32S+4He
SD(40Ca)- 28Si + 12C
HD(44Ti)- 28Si + 16O GS
oblate
Stable configurations (shape isomers) in 36Ar
J.Darai et al. PRC 80, (2009) and
EPJ Web of Conferences 17, (2011)

8. „Molecular” (collective ) states close to 40Ca
resonances 12C+24Mg , 16O+20Ne
Binary configurations
b =
GS, SD bands
SD(40Ca)- 28Si + 12C
HD(44Ti)- 28Si + 16O
Stable configurations (shape isomers) in 36Ar
J.Darai et al. PRC 80, (2009) and
EPJ Web of Conferences 17, (2011)

9. Expected High spin deformed bands in 40Ca
Cranked Relativistic Mean-Field (CRMF) → deformed „cluster states” favoured at high spin
proton densities SD HD MD
terminating states
D. Ray, A. V. Afanasjev, PRC 94, (2016)

10. Expected High spin deformed bands in 40Ca
Cranked Relativistic Mean-Field (CRMF) → deformed „cluster states” favoured at high spin
proton densities SD HD
no band termination of
S-,H-,M- deformed bands MD
D. Ray, A. V. Afanasjev, PRC 94, (2016)

11. Jacobi Shape Transition
oblate→ triaxial → prolate
A.Maj et al., N.Phys. A731, 319 (2004)
A.Maj

12. Jacobi Shape Transition
GDR + particle decay
A.Maj

13. Survival of large deformation in 46Ti (CN)
M. Lach et al., Eur Phys J. A12, 381 (2001)
42Ca
2p2n
46Ti sp nd
GDR- SD feeding
EUROBALL + HECTOR
105 MeV 18O + 28Si  46Ti* SD SD
M. Kmiecik et al., Acta Phys. Pol. B (2005)

14. JST discovery at VIVITRON
EUROBALL IV (26 clovers + 15 clusters + 75% InnerBall )
HECTOR (8 big BaF2 ) – eff. : 1% for MeV
EUCLIDES (Si DE/E)
Selection of high spins:
2 clean Ge  1 BaF  IB fold >3
105 MeV 18O + 28Si  46Ti - lmax  35 , E* = 88 MeV

15. Deformation in 44Ti beyond SM- Cluster Model
di-nucleus
𝜷~𝟎.𝟕 HD SD GS
44Ti
16O
28Si
4ħw
0ħw
Predicted at E*~20 MeV
M.Kimura, H.Horiuchi NPA (2006)

16. Bands in 44Ti 44Ti 𝜷~𝟎.𝟒−𝟎.𝟑 SD: a a 1ħw 4ħw 0ħw Reflection symmetric
N.Antonenko- priv. comm.
36Ar
SD: a a
5p-1h
1ħw
4ħw
8p-4h
0ħw
Reflection symmetric
GS band
C.D.O’Leary et al., PRC61,064314(2000)

17. Bands in 44Ti 44Ti a Reflection asymmetric 1ħw 4ħw 0ħw
40Ca a
Reflection asymmetric
Centrifugal barrier (J=21-) -competing g and a emission at high spin ?
G. G. Adamian et al., PRC 92, (2015)
5p-1h
1ħw
4ħw
8p-4h
0ħw
GS band
C.D.O’Leary et al., PRC61,064314(2000)

18. GANIL experiment
Investigation of a high spin structure in 44Ti via discrete and continuum  spectroscopy with AGATA, PARIS and DIAMANT at GANIL (accepted in 2014)
to be performed in 2018

19. Studies of 44Ti- focus on HS
High energy (>5MeV) g-rays (E1, GDR) feeding the SD
Extension/termination of rot. bands (by disrete g-rays)
Gamma-a particles correlations
PARIS
DIAMANT
AGATA

20. Experimental set-up at GANIL
Triple-g AGATA
Double-g AGATA-PARIS

21. Experimental set-up at GANIL
Triple-g AGATA
Double-g AGATA-PARIS
Reaction channel selection and particle ang. distr. DIAMANT

22. Experimental set-up at GANIL

23. COULEX of SD in 42Ca at LNL DANTE: 3 MCP detectors
covered θ range 100°-144°
beam:
42Ca, 170 MeV
(85% Coulomb barrier)
target :
208Pb, 197Au
particle- coincidence
AGATA: 3 clusters
at mm from the target
1st AGATA experiment at LNL (2010)
(A.Maj, P.Napiorkowski, F.Azaiez et al.)

24. COULEX of 42Ca- results 42Ca Exc. band GS band
low lying bandhead accesible by COULEX
GOSIA COULEX code
K. Hadyńska-Klęk, et al. PRL 117, (2016)

25. COULEX of 42Ca- results exc. band (SM) 4p-2h, 6p-4h
b2, g=0.43(4), 13(+5,−6)◦
D. Ray, A. V. Afanasjev, PRC 94, (2016)
exc. band (SM) 4p-2h, 6p-4h

26. Planned COULEX experiments
Coulomb excitation of super-deformed band in 40Ca, P.J.Napiorkowski, A.Maj, F.Azaiez et al.
IPN, Orsay- ORGAM, PARIS (2 Clusters), LuSIA (to be done in 2018)
Coulomb excitation of 45Sc (low lying shape isomer)
M.Matejska-Minda, P.J. Napiorkowski, R.Kumar, et al.
IUAC, New Delhi- 4HPGe Clovers, PPAC (Nov. 2017)

27. GALILEO and RFD at LNL Legnaro
Recoil Filter Detector
GALILEO
Studies of deformed bands in 28Si-48Cr
30 GASP detectors
10 triple (EB) clusters
efficiency ~8%
W.Meczynski et al., NIM A80, 1310 (2007).

28. Recoil Filter Detector
𝑻𝒐𝑭→ 𝒗 𝑹𝑬𝑪
RFD is a set of HI detectors for evaporation residues in coincidence with g-rays
RFD
Time-of-Flight technique allows to deduce actual velocity of every recoil
Filter out of unwanted reaction channels: scattered beam, Coulex, fission fragments
Ge array- GASP
W. Męczyński et al., NIM A580, 1310 (2007)

29. RFD and GASP at LNL, AD 2009
g-singles
69As recoils at v/c=3%
Doppler broadening reduction
32S (95MeV) + 40Ca →72Kr(CN)
Shape evolution at high spin in some A~70 nuclei
M.Matejska-Minada, PhD, 2014

30. GASP + RFD 32S (95MeV) + 40Ca →72Kr(CN)
Short lifetimes- DSAM
ground state trans.
high-spin trans.
69As
t ~ ps
t ~10 fs
Emission in vacuum
Emission in target
GASP + RFD 32S (95MeV) + 40Ca →72Kr(CN)

31. Shape evolution in 69As at high spins
high w
M. Matejska-Minda et al. Acta Phys. Pol. B (2013)
and PhD thesis (2014), PRC in preparation
p(g9/2)1
K=3/2
oblate-prolate-oblate
32S (95MeV) + 40Ca →72Kr(CN)
69As
low w

32. Conclusion Renewed interest in SD studies near 40Ca
New theory approaches (cluster model, CRMF, …)
Application of modern instruments for HS studies: AGATA, GALILEO(RFD), PARIS
Complementary COULEX experiments (structure near SD band heads)

33. Thank You; To be continued at…
Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape"
Zakopane, Poland,

34. Advances in theoretical and experimental Nuclear Physics:
Structure of exotic nuclei, from very light to SH,
Nuclear isomerism,
Collective excitations at extreme spins and temperatures,
Nuclear reactions (fragmentation, fission, DIC, etc.),
Challenges at the radioactive ion beam facilities, methods and detectors.
Applications of Nuclear Physics in Astrophysics, Medicine, Power production.
Daily trips to the Tatra mountains
Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape"
Zakopane, Poland,