Fusion08 : Summary talk. L.Corradi

Transcription

1 σ Fusion08 : Summary talk V E L.Corradi Laboratori Nazionali di Legnaro INFN, Italy r Fusion08, Chicago, September 22-26, 2008

2 A schematic view view of of fusion fusion reactions E << E b E ~ E b E > E b σ σ µb - mb σ ~ mb nb - µb E E E V V V r r r - σ steep fall off - CC effects - fusion hindrance -structure of V N at r < r B - connection with astrophysics - D(B) from fusion and QE processes - connection with surface vibrations and transfer - σ fusion < σ capture - connection with QF, MNT, DIC, BU

3 binary reactions QE/MNT mechanism, DIC collisions, nuclear spectr. in n-rich regions weakly bound/clusters reactions with He,Li,Be,B effects of break up, cluster structures fission dynamics QF processes, fission fragment distributions, entrance channel effects near barrier region D(B) from QE scattering, CC methods, mean field dynamics, heavy RIB s σ heavy/superheavy SHE formation, SHE decay studies and spectroscopy, DIC for SHE production sub-sub-barrier fusion positive Q-val. systems, density dependent forces, structure of V N E astrophysics radiative capture, Hoyle states,screening effects, r-process Fusion08 : an overview

4 Astrophysics

5 Late stages of stellar evolution 12 C+ 12 C importance: evolution of massive stars Gamow region: 1 3 MeV min. measured E: 2.1 MeV (by -ray spectroscopy) Strieder, J. Phys. G35 (2008) Crab Nebula SN Spillane et al. Aguilera et al. Becker et al. High and Cujec Patterson et al Jiang et al. Gasques et al. Caughlan and Fowler PA KNS [MeV b] S * tot E cm [MeV] still far from required accuracy for stellar models Aliotta

6 Extrapolation to stellar energies? Different potential models leads to different extrapolation of low energy cross section (S-factor). Extreme case, standard potential model hindrance potential model S( E) ( E) E exp(2 ) Caughlan & Fowler ADNDT 40 (1988) 283; Gasques et al. PRC 72 (2005) Yakovlev et al. PRC 74 (2006) ; Jiang et al. PRC 75 (2007) Wiescher

7 New calculations for 16 O+ 16 O Jiang T. Neff et al., arxiv: v2(07) Fermionic Molecular Dynamics model A.Diaz-Torres et al., Phys.Lett.B652,255(08) Realistic two-center Shell Model C.J.Horowitz et al., Phys.Rev.C77,045807(08) Barrier-penetration model H.Esbensen, Phys.Rev.C77,054608(08) Shallow potential model

8 First measurement for heavy-ion fusion hindrance in a positive Q-value system Hindrance observed C.L.Jiang et al., Phys. Rev. C78, (2008)

9 What happens in medium-light systems? Heavy, Q<0 Light, Q>0? 36 S + 48 Ca Q>0 36 S + 64 Ni Q<0 It is easy to show that for Q>0 S(E) may not show any maximum no fusion hindrance! C.L.Jiang et al., PRC 75, (2007) Stefanini

10 The excitation functions of 36 S + 48 Ca and 36 S + 64 Ni have different slopes below the barrier Stefanini Montagnoli

11 Nucleus-nucleus potential

12 M3Y+repulsion vs. Akyüz-Winther Misicu

13 S-factors (from Medium Heavy to medium Light Ions) ARGONNE DATA : red circles ( C.L. Jiang, Phys.Rev. C 78, (2008). C.L. Jiang, Phys.Lett.B. B640, 18(2006).

14 Deep Subbarrier Fusion Reactions (i) Subbarrier energies (E > V touch ) The inner turning point is outside of the touching point. (ii) Deep subbarrier energies (E < V touch ) The inner turning point is in the overlap region. The steep fall-off phenomenon can be attributed to the dynamics after the target and projectile touch with each other. Ichigawa Sudden Approach The fusion takes place so rapidly Adiabatic Approach The dynamical change in the density

15 Difference Between Two Approaches Both the sudden and adiabatic models provide similar results for the fusion cross sections. What is a difference between these two models? The average angular momentum of compound nuclei! Adiabatic Mişicu and Esbensen, Phys. Rev. C 75, (2007) Sudden By measuring the average angular momentum, we may discriminate the two approaches.

16 Where do dissipative effects start to occur? Dissipative Coherent quantum superposition If dissipation starts well inside - then current methods to model fusion ok - no effect on observables Dissipation can occur at larger separations Dasgupta

17 Real energy loss before fusion reduction in fusion Does this play a role in reduced fusion σ at above barrier energies? O Pb (mb) 500 Suppression 0.86 ± CC calc., WS pot. (a = 0.66 fm) E V b (MeV)

18 Correlation between reaction channels quasi elastic, deep inelastic fusion quasi fission, [...] In the presence of couplings the energy of relative motion is not well defined. An exchange of energy from the relative motion to the intrinsic degrees of freedom takes place Corradi (Fusion06)

19 Quasi-elastic reactions

20 Quasielastic barrier distributions : : role role of of particle transfer channelsc Data : Mitsuoka et al, PRL99,182701(2007) G.Pollarolo,PRL100,252701(2008)

21 Szilner

22 New results for N 28 Ca and K isotopes Identification of new short-lived states in 49Ca ( p, f 1/2 5/2 single particle energies) and 50Ca ( 2+2 ) R. Broda et al. A new 7/2 isomer in 47K Observation of excited states in 48K and 49K R. Broda et al. Broda W. Królas et al. 6

23 multinucleon transfer : : experiment vs. vs. theory theory data : LNL theory : GRAZING code and CWKB Corradi

24 exp. neutron transfer yield Ni+ Ni Sn Sn coupling scheme near and sub-barrier transfer sub-barrier fusion Fusion+Deep Inel. Fusion Evap.Res. +Multiphonon Tr+Inel 2 +,3 - Transfer 1-dim. C.L.Liang et al, PRC57(1998)2393 H.Esbensen et al, PRC57(1998)2401

25 MNT, MNT, Fission, ER ER and and Capture cross cross sections Argonne data G.Pollarolo

26 Unstable/Weakly bound bound nuclei nuclei

27 Raabe

28 Lemasson

29 Shapira

30 Cluster effects in in nuclear reactions

31 Resonances in heavy-ion collisions The case of the identical boson collisions 12 C+ 12 C, 14 C+ 14 C, 16 O+ 16 O, 24 Mg+ 24 Mg, 28 Si+ 28 Si Weak absorption and the number of open channels Resonant structures in the excitation functions of various channels: elastic, inelastic, transfer and fusion Haas

32 Funaki RIKEN Itoh, M. et al. Nucl. Phys. A 738, (2004) Funaki - RIKEN Freer

33 Effects of the transfer coupling : Minimum coupling Solid : Full calculation S S S f,i 2 f,i 2 f,i 2 1 S f,i He x He+ y He 5He+7He I=0 5He+7He I=2 Elastic ( X 1/4 ) 6He+6He E c.m. ( MeV ) Sharp resonant structures are generated by Transfer Coupling New aspects!! Dotted curves + 8 He g.s. + 8 He(2 1+ ) 5 He(3/2 - ) + 7 He(3/2 1- ) 5 He(3/2 - ) + 7 He(1/2 1- ) 5 He(3/2 - ) + 7 He(5/2 1- ) 5 He(1/2 - ) + 7 He(3/2 1- ) 6 He g.s. + 6 He g.s. 6 He g.s. + 6 He(2 1+ ) 6 He(2 1+ ) + 6 He(2 1+ ) Ito

34 Quasi-fission, Heavy Heavy and and Superheavy elements

35 Do shell effects drive or modulate Q-F mass distributions? 48 Ti: M R distribution vs. 2 and Z C.N. Gaussian standard deviation M at E ~ V B E ~ V B M Static Z C.N M Hinde

36 46,48,50 Ti + 186,184,182 W 232 Cm 96 Deformation alignment dominant 50 Ti E X 48 Ti (E X +7) 46 Ti (E X +13) Hinde et al., PRL 100 (2008)

37 Summary and outlook - Present and Near Future 120 shellcorrection ms [MeV] ms 6 ms 20ms 50ms ** ms 0.1 s s 0.5 s 0.6 s 3 s s 73ms 0.1 s 0.5 s s 1 ms 4 s 0.1 s 30 s Rg 3 ms 6 ms 4.2ms 0.2 s 4 s Ds? 200 s 100 s 56 s 170 s 0.2 s 10 s Mt 2 ms 30ms 5 ms 0.44 s 10ms 0.8 s s 108 Hs? 0.5ms 2 ms 2 ms 50ms 14 s 4 s 107 Bh 10ms 0.1 s 1 s 1 s 1 s 17 s 61 s? 10 s decay SHE SHE synthesis 106 Sg 3 ms 0.5 s 4 ms 0.1 s 7 ms 1 s 7 s 21 s 2 m mode h 105 Db 1.6 s 1.6 s 1.5 s 4 s 0.5 s 1.5 s 2 s 30 s 30 s 22 m 29 h Ca- Ca Ni+ Ni U 104 Rf 50 s 20 s 1.6 s 6 ms 4 s 10ms 3 s 20ms 1 m 2 s 15 m 1,3 h 185 mid-term 103 Lr 0.4 s 0.6 s 10 s 20 s 30 s 0.5 s 4 s 6 s 3 m 40 m 4 h 102 No 50 s 6 s 1 s 3 s 2 m 1 m 3 m 3 s 30 s 1 ms 1 h 0.1 s 5 ms heavier actinide targets (e.g. (e.g Cm) Cm) SF 101 Md 1 s 0.2 s 7 s 30 s 1 m 4 m 2 m 6 m 30 m30 m 1 h 6 h 50 d 1 h 30 d + /EC 40 s 100 Fm nuclear structure 4 s 1 s 40 s 3 m 30 m 5 h 25 h 3 d 3 h 20 h 3 h 100d 400 s 1.5 s - 99 Es 37 s 1 m 8 m 5 m 30 m 2 h 8 h 33 h 1 yr 20 d 1 yr 40 d 30 m 8 d trend trend of of single single particle levels 98 Cf 10 m19 m45 m 35 h 3 h 1 yr 0.4kyr 13 yr 0.9kyr 3 yr 15 d 60 d 1 h 12 m 180levels (( A A Md, Md, A A Es) Es) K-isomers in in 252, ,254 No No and and Ds Ds near 165 near future intensity increase (UNILAC upgrade) with with TASCA towards n-rich n-rich and and high high Z Ackermann

38 Thank you very much! See you all at the next Fusion Conference

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40 cluster cluster effects in in nuclear reactions - 12 C+ 16 O radiative capture reactions (Courtin) - 24 Mg+ 12 C systems, α-clustering phenomena (Beck) - α-cluster structure in light N Z nuclei (Goldberg) - cluster spectroscopic studies in 7 Be and 7 Li (Guimares) - cluster structures and U(3) dynamical symmetry (Cseh)

41 Unstable/Weakly bound bound nuclei nuclei - cross section measurements for 8 B+ 58 Ni (Kolata) - fusion of 8 Li+ 208 Pb (Aguilera) - 9,10,11 Be+ 64 Zn reaction studies (Figuera) - CF and ICF of 6 He and 6 Li induced reactions (Krupko) - study of 6 Li+ 59 Co (A.Szanto de Toledo) - exclusive measurements of break-up in 7 Li+ 144 Sm (Pacheco) - role of the continuum in reactions with weakly bound nuclei (Vitturi) - static and dynamical effects in break-up (Gomes) - reactions with the double borromean nucleus 8 He (Lemasson)

42 Nucleus-nucleus potential Misicu (density-dependent forces), Ichigawa (one-body barrier), Hagino (potential inversion), Dasgupta (irreversibility), Diaz-Torres ( environment ) Washiyama (dynamical mean field theory), Lacroix (Stochastic Meanfield dynamics), Broomfield (beyond TDHF)

43 Astrophysics - indirect methods for nova nucleosynthesis: gamma spectroscopy, transfer reactions (Jenkins) - 130,132 Sn(d,p), 134 Te(d,p) reactions, impact on element production in the r-process (Jones) - 12 B(d,p) reactions, determination of spectroscopic factors, deduced rates for neutron capture (Young Lee) - 27 Al( 3 He,t) 27 Si * (p) 26 Al, 28 Al( 3 He,α) 27 Si*(p) 26 Al, measured angular correlations to constrain spins, deduced 26m Al(p,γ) 27 Si rates (Deibel) - Triple-alpha process in hot astrophysical scenario, used 12 B (Patel) - Electronic and Ion screening in low energy nuclear reactions (Kasagi)