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,g) rates in the non-equilibrium canonical model
Nuclei photodisintegration
Statistical model of compound nuclear reaction : Hauser-Feshbach Tn
Sn+En
(Z,A) + n
Tg = TE1(E) r(E) dE Sn
(Z,A+1)
Photon transmission
coefficient sensitive to : Tg
the E1 strength distribution TE1(E)
the level density r(E)

4. Why using microscopic calculations ?
Phenomenologic
Fast and simple to use
Extrapolations ?
No feedback about nuclear structure
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 E1 E1

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

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

7. 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 : e[r,k]
Since Year ~ 2000
Skyrme functionnal
ρ=<ψ+(r)ψ(r)> : particle density
κ=<ψ(r)ψ(r)> : pairing density HF
RPA
E (MeV)
r (fm-3)
E. Khan, N. Sandulescu, Nguyen Van Giai, M. Grasso PRC66 (2002)

8. Comparison with experiment
GDR centroids
(cf experiment #1)
SLy4
rms on GDR centroids :
SIII keV
SGII 573 keV
SLy4 457 keV
MSk7 564 keV
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
(48 spherical nuclei)

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

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

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

12. Ultra High energy Cosmic Rays
E= eV
GZK
Ankle
~ E-3
Redressed spectrum (x E3)

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

14. = * Propagation of UHECR Photodisintegration rate (~1h-1)
2.7 K Cosmic Microwave Background
Photodisintegration cross section
g=2.1010
GDR
56Fe : 1021 eV *
Photons density
Lorentz boosted 10
100
0.1 1 10
100
1000 =
E (MeV)
E (MeV)
Photodisintegration rate (~1h-1)

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

16. Photodisintegration (II)55 54 53 52 51 50 49 48 47 45 44 43 41 40 38 39 37 36 34 35 30 26 22 18 15 14 13 11 9 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 35 36 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 13 12 11 10
: PSB path
Z=8
Z=14
Z=18
Z=22
Z=26 Z N A
Photodisintegration (II)

17. Usefull for many other applications
Experiment #3
E1 strength for A<56 nuclei close to the valley of stability
Very High intensity : 109 pps for 37,39Ar
UHECR campain ?
Usefull for many other applications

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

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

20. 2) Exotic modes

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

22. The inner crust
~ r0
~ 0.5 r0
Wigner-Seitz cells

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

24. Experiment #4 on the most neutron-rich Sn available (138Sn)
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 (138Sn)

25. Giant pairing vibrations
2n transfer
GPV : high energy mode
never observed
Khan PRC69(2004)014314

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

27. 3) Surprise

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

29. PRELIMINARY Charlotte Monrozeau PhD thesis
56Ni excitation energy spectrum
PRELIMINARY
E* (MeV)
N (/500 keV)
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, b 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 nuclei drip-line nuclei Fermi gas

31. Microscopic models improvements
Neutron average pairing field
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
124Sn
Dn (MeV)
Pairing phase transition
T (MeV)

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

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

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

35. Specific heat of collective modes
1800Sn
Entropy :
Scoll=SQRPA-SHFB L=

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. The QRPA residual interaction
Skyrme force and surface pairing interaction
SLy4 force h
EQP < 60 MeV