Download presentation

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

Similar presentations

OK

David Argento (some aspects of) cosmogenic nuclide production.

David Argento (some aspects of) cosmogenic nuclide production.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Disaster management ppt on uttarakhand disaster Ppt on remote operated spy robot with camera Ppt on different means of transport Ppt on bluetooth controlled robot Best ppt on science and technology Business ppt on flipkart online Ppt on extinct species of plants and animals Ppt on chapter 12 electricity suppliers Ppt on narendra modi free download Ppt on computer vs books