1. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 1 D. Habs LMU München Fakultät f. Physik Max-Planck-Institut f. Quantenoptik A Laser-Accelerated Th Beam is Used to Produce Neutron-Rich Nuclei Around the N=126 Waiting Point of the r-Process Via the Fission-Fusion Reaction Mechanism

2. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 2 A laser-accelerated Th beam is used to produce neutron-rich nuclei around the waiting point N = 126 of the r-process via the fission-fusion mechanism Radiation Pressure Acceleration (RPA) Atomic stopping of dense ion bunches The astrophysical r-process and the N = 126 waiting point Experimental setup Outline New nuclear and astrophysics with APOLLON

3. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 3 Ion acceleration TNSA (target-normal sheath acceleration) Low conversion efficiency Huge lasers are required Laser acceleration schemes Former schemes S.C. Wilks et al., Phys. Plasmas 8, 542 (2001).

4. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 4 Normalized areal electron density: Normalized vector potential: Optimum ion acceleration for Optimum electron acceleration for ions electrons New Acceleration Mechanism = dimensionless S.G. Rykovanov et al., New J. Phys. 10, 113005 (2008). O. Klimo et al., Phys. Rev. ST AB 11, 031301 (2008).

5. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 5 Radiation pressure acceleration (RPA) Cold compression of electron sheet. Rectified dipole field between electrons and ions. Neutral bunch of ions + electrons accelerated. Solid-state density: 10 24 e cm –3 Classical bunches: 10 8 e cm –3 Very efficient!

6. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 6 Laser Power: 15 TW (700 mJ in 45 fs) Focused Intensity: a L = 5, Contrast: > 10 11 A. Henig et al.,“Radiation pressure acceleration of ion beams driven by circularly polarized laser pulses”, Phys. Rev. Lett. 103, 245009 (2009). RPA ion accel. + DLC foils (I) Peak at very low target thickness of 5.6 nmCold target for circular polarization Max-Born Institute (MBI), Berlin

7. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 7 RPA ion accel. + DLC foils (II) Hot electronscold electrons Experiment Theory 2D PIC simulations

8. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 8 RPA ion accel. + DLC foils (III) Theory 2D PIC simulations electrons ions Phase space rotation Peak in ion spectrum

9. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 9 RPA ion accel. + DLC foils (IV) Theory Hot electrons exploding foilCold electrons  = 61 fs

10. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 10 RPA ↔ TNSA Ion acceleration RPA: much higher conversion efficiency at short pulse durations. Ultra-thin foils: MBI-laser (Berlin) 45 fs Trident-laser (LANL) 500 fs

11. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 11 RPA ↔ TNSA Ion acceleration

12. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 12 Experimental requirements 1)Ultra-high contrast → Double plasma mirror 2)Ultra-thin target foils I/  or I/  controls acceleration Target technology is important

13. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 13 Chart of the Nuclides r-process and waiting points Superheavies: Z = 110, T 1/2 = 10 9 a ? recycling of fission fragments ?

14. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 14 r-process Solar abundances

15. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 15 r-process Supernova II explosions and neutron star merger Neutron star merger Supernova type II explosion

16. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 16 Nuclear masses Theories and experiment

17. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 17 Fission-fusion reaction 10 MeV/u H, C, O, 232 Th, beam + 232 Th target a) FissionH, C, O + Th → F L + F H fission fragments in target 232 Th + 232 Th → fission of beam in F L + F H Reaction of radioactive short-lived light fission fragments of beam + Radioactive short-lived light fission fragments of the target b) Fusion:F L + F L → A Z ≈ 200 80nuclei close to N=126 waiting point F L + F H → 232 Thold nuclei F H + F H → unstable

18. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 18 Stopping power of ion bunches with solid state density Bethe-Bloch formula for individual ion: a) enhanced stopping (10 5 ×) in low-density targets dense bunch interacts with collective wake → reduced fraction of nuclear reaction b) reduced stopping in solid target first electrons of bunch kick out electrons of foil like a snow plow. → enhanced fraction of nuclear reactions. binary collisions k D = Debye wave number long-range collective interaction  p = plasma frequency

19. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 19 Experimental setup

20. Dietrich Habs ELI Photonuclear Bucharest, Feb 2, 2010 20 Fission-fusion experiment 1)Study RPA acceleration of heavy elements: efficiency, target shaping, yields 2)Study atomic stopping power of dense ion bunches 3)Perform fission-fusion experiment Estimated yield: 3·10 6 s -1 A = 180 - 190