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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
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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
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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+
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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)
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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
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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)
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„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)
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„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)
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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)
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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)
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Jacobi Shape Transition
oblate→ triaxial → prolate A.Maj et al., N.Phys. A731, 319 (2004) A.Maj
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Jacobi Shape Transition
GDR + particle decay A.Maj
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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)
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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
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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)
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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)
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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)
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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
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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
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Experimental set-up at GANIL
Triple-g AGATA Double-g AGATA-PARIS
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Experimental set-up at GANIL
Triple-g AGATA Double-g AGATA-PARIS Reaction channel selection and particle ang. distr. DIAMANT
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Experimental set-up at GANIL
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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.)
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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)
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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
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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)
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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).
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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)
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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
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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)
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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
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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)
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Thank You; To be continued at…
Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape" Zakopane, Poland,
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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,
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