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Giant resonances, exotic modes & astrophysics 1) The dipole strength : r-process Ultra-High Energy Cosmic Rays 2) Exotic modes : SuperGiant Resonances.

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Presentation on theme: "Giant resonances, exotic modes & astrophysics 1) The dipole strength : r-process Ultra-High Energy Cosmic Rays 2) Exotic modes : SuperGiant Resonances."— Presentation transcript:

1 Giant resonances, exotic modes & astrophysics 1) The dipole strength : r-process Ultra-High Energy Cosmic Rays 2) Exotic modes : SuperGiant Resonances Giant Pairing Vibrations 3) Surprise ? E. Khan

2 1) The dipole strength

3 The role of dipole strength in nuclei (de)-excitation r-process : (n,  ) rates in the non-equilibrium canonical model Nuclei photodisintegration Statistical model of compound nuclear reaction : Hauser-Feshbach Photon transmission coefficient sensitive to : SnSn TnTn (Z,A) + n (Z,A+1) T   T E1 (E)  (E) dE 0 S n +E n TT the E1 strength distribution T E1 (E) the level density  (E)

4 Why using microscopic calculations ? Microscopic Efforts consuming ? More suited to extrapolate far from stability : neutron skin Characterize the n-n interaction on the whole nuclear chart Test the model validity on a large scale Lorentzian (Hybrid)Microscopic Phenomenologic Fast and simple to use Extrapolations ? No feedback about nuclear structure E1

5 Impact on astrophysical predictions Effect of the Pygmy Resonance Maxwellian averaged (n,  ) rates r-abundance distributions S. Goriely, PLB436 (1998) 10 GDR+PR GDR

6 Systematics E1 strength measurements for neutron rich unstable nuclei below S n Relativistic Coulomb excitation : AGATA MeV/u 70 Ni High Z Experiment #1

7 HF RPA Meanwhile : microscopic prediction of the E1 strength Collective excitation in superfluid system QRPA in linear response : small amplitude limit of the perturbed TD-HFB equations harmonic oscillations Connected to the Density Functional Theory :   Since Year ~ 2000 Skyrme functionnal ρ= : particle density κ= : pairing density E. Khan, N. Sandulescu, Nguyen Van Giai, M. Grasso PRC66 (2002) E (MeV)  (fm -3 )

8 Comparison with experiment GDR centroids (cf experiment #1) rms on GDR centroids : SIII 2267 keV SGII573 keV SLy4457 keV MSk7564 keV SLy4 (48 spherical nuclei) BSk7 : rms on 2135 masses : 676 keV rms on 48 GDR centroids : 485 keV interactions developed with both ground and excited states features on a large scale

9 Experiment #2 Low energy section of EURISOL : masses,  decay,... Inputs : E1, level densities, masses, optical model potential Validity : high level density S n not too small Direct captures are not negligible for neutron-rich nuclei

10 (n,  ) rates Deviation up to a factor 10 QRPA/Hybrid QRPA/QRPA T= K Discrepancy pheno/micro Agreement HF+BCS QRPA / HFB QRPA S. Goriely, E. Khan, M. Samyn, NPA739 (2004) 331

11 Are Ultra-High Energy Cosmic Rays made of nuclei ? The Pierre Auger collaboration GRB990123

12 Ultra High energy Cosmic Rays E= eV Ankle GZK Redressed spectrum (x E 3 ) ~ E -3

13 Composition, acceleration & propagation Open question ! Extra-galactic particles : protons nuclei ( 56 Fe, …) ? Open question ! Gamma Ray Bursts, Active Galaxy Nucleus ? N(E)~E -  Quantitative answers Interaction with the 2.7 K Cosmic microwave background Extra-galactic Magnetic fields Comparison with the measured spectrum on Earth (AUGER, …) COMPOSITION : ACCELERATION : PROPAGATION :

14 Propagation of UHECR 2.7 K Cosmic Microwave Background Photons density E (MeV)  = Lorentz boosted * E (MeV) Photodisintegration cross section GDR = Photodisintegration rate (~1h -1 )  Fe : eV

15 Photodisintegration (I) Pheno. and microscopic models to predict the GDR strength Photodisintegration calculated within Hauser-Feshbach formalism 55 Mn ( ,1nx) 51 V ( ,1nx) Full network with beta decay rate (~ r-process)

16 : PSB path Z=8 Z=14 Z=18 Z=22 Z=26 Z N A Photodisintegration (II)

17 Experiment #3 UHECR campain ? Usefull for many other applications E1 strength for A<56 nuclei close to the valley of stability Very High intensity : 10 9 pps for 37,39 Ar

18 Impact on astroparticle propagation Source : 56 Fe E. Khan, S. Goriely, D. Allard, E. Parizot, et al, Astr. Phys. 23 (2005) 191

19 Needs for a galactic CR : Ankle is the galactic/extra-galactic transition Protons only :  =2.6 Protons & Nuclei :  =2.3 Interpretation of the ankle D. Allard, E. Parizot, A.V. Olinto, E. Khan, S. Goriely, A&A 443 (2005) 29

20 2) Exotic modes

21 SuperGiant Resonances in neutron stars Nuclear matter : not only a toy for theoreticians

22 The inner crust Wigner-Seitz cells ~   ~ 0.5  

23 Supergiant resonances L=1 L=2 71% EWSR QRPA HFB E. Khan, N. Sandulescu, Nguyen Van Giai, PRC71 ( ~ Excitations of drip-line nuclei immersed in neutron gas

24 Experiment #4 Specific heat : spectroscopy of drip-line nuclei drives the excitation spectrum of the Wigner-Seitz cells (low-lying states) Coulex or integrated (p,p’) on the most neutron-rich Sn available ( 138 Sn)

25 Giant pairing vibrations Khan PRC69(2004) n transfer GPV : high energy mode never observed 22 O+2n

26 Experiment #5 Exotic nuclei : Q value matched for high energy states Search for the GPV 208 Pb ( 12 Be, 10 Be) at ~ 10 MeV/u

27 3) Surprise

28 GMR in unstable nuclei MAYA active target 56 Ni(d,d’) at 50 MeV/u (GANIL)

29 PRELIMINARY E* (MeV) N (/500 keV) 56 Ni excitation energy spectrum Charlotte Monrozeau PhD thesis

30 Outlook Dipole modes plays a crucial role in nuclei de-excitation Microscopic treatment necessary to draw conclusions on r-process abundances Nature of UHECR Needs for Masses,  decay Systematic E1 data Low lying states close to the drip-line 2 neutron transfer reactions with exotic nuclei Collective excitations in stable nuclei exotic nucleidrip-line nuclei Fermi gas

31 Finite temperature effects HFB+QRPA Future : - microscopic treatment of the width - better treatment for odd nuclei - microscopic treatment of the deformation - phonon coupling calculations - drip-line nuclei : coupling between continuum and pairing effects : exact continuum calculations Microscopic models improvements Neutron average pairing field Pairing phase transition T (MeV)  n (MeV) 124 Sn

32 Comparison with the data Monte-Carlo using a extragalactic source with energy distribution ~ E -  CMB : *Protons :  photoproduction and e+-e- pairs production *Nuclei : photodisintegration and e+-e- production Infra Red background Non-negligible effect with the forthcoming AUGER data

33 Magnetic field effect on the propagation of UHECR Nuclei in the acceleration process Comparison with the AUGER data Next

34 Low and high density WS cells Skyrme-HFB calculations with density dependent pairing interaction Non-zero value of  at the border of the WS cell Size of the WS cells : 1800 Sn : 28 fm 982 Ge : 14 fm N. Sandulescu PRC 69 (2004)

35 1800 Sn Specific heat of collective modes L=0 4 Entropy : S coll =S QRPA -S HFB

36 Température dans les noyaux Transition de phase superfluide Noyaux exotiques chauds : pairing+continuum+température E. Khan, Nguyen Van Giai, M. Grasso NPA731(2004)311

37 Accelerators of the Universe GRB GANIL

38 SLy4 force  The QRPA residual interaction Skyrme force and surface pairing interaction E QP < 60 MeV


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