1. Peter G. Thirolf, LMU München The ‘Fission–Fusion‘ Reaction Mechanism: Using dense laser-driven ion beams for nuclear astrophysics for nuclear astrophysics Outline:  motivation: nucleosynthesis of heavy elements  r process path: waiting point N=126  ultra-dense laser-accelerated ion beams  novel reaction mechanism: fission-fusion  experimental requirements at ELI-NP Peter G. Thirolf, LMU Munich ELI-NP Workshop, Bucharest, March 10-12, 2011

2. Peter G. Thirolf, LMU München r process: waiting point N=126 - waiting point N=126: bottleneck for nucleosynthesis of actinides - last region of r process ‘ close ’ to stability  r process: - path for heavy nuclei far in ‚terra incognita‘ - astrophysical site(s) still unknown: core collapse SN II, neutron star merger ? Au, Pt, Ir,Os ELI-NP Workshop, Bucharest, March 10-12, 2011

3. Peter G. Thirolf, LMU München - cold compression of electron sheet, followed by electron breakout - dipole field between electrons and ions - ions + electrons accelerated as neutral bunch (avoid Coulomb explosion) - solid-state density: 10 22 - 10 23 e/cm 3 ‘classical’ bunches: 10 8 e/cm 3 Radiation Pressure Acceleration driver laser ionselectrons nm foil relativ. electrons at solid density  ~ 10 14 x density of conventionally accelerated ion beams ELI-NP Workshop, Bucharest, March 10-12, 2011

4. Peter G. Thirolf, LMU München Exp. Scheme for “Fission-Fusion” ELI-NP Workshop, Bucharest, March 10-12, 2011 ~ 1 mm Fission fragments Fusion products Reaction targetProduction target CD 2 : 520 nm CH 2 ~ 70  m 232 Th: ~ 50  m 232 Th: 560 nm APOLLON laser : 1.2. 10 23 W/cm 2 32 fs, 273 J, 8.5 PW 1.0. 10 22 W/cm 2 32 fs, 23 J, 0.7 PW focus: ~ 3  m 232 Th + p, C → F L + F H : beam-like fission fragments beam (~ 7 MeV/u): d, C, 232 Th target: p, C, 232 Th d, C + 232 Th → F L + F H : target-like fission fragments D. Habs, PT et al., Appl. Phys. B, in print

5. Peter G. Thirolf, LMU München Fission Stage of Reaction Scheme 232 Th: ~ 91,  A L ~ 14 amu (FWHM)  AL ~ 22 amu (10%) ~ 37.5 (Rb,Sr) FLFL FHFH  fission mass distribution: ELI-NP Workshop, Bucharest, March 10-12, 2011  fusion-evaporation calculations (PACE4): (Z=35,A=102) + (Z=35, A=102): E lab = 270 MeV (E* = 65 MeV) 190 Yb (Z=70,N=126): 2.1 mb 189 Yb ( N=125): 15.8 mb 188 Yb ( N=124): 61.7 mb 187 Yb ( N=123): 55.6 mb

6. Peter G. Thirolf, LMU München Collective Stopping Power Reduction binary collisions k D = Debye wave number long-range collective interaction  p = plasma frequency  Bethe-Bloch for individual ion:  reduction of atomic stopping power for ultra-dense ion bunches: - plasma wavelength (~ 5 nm) « bunch length (~560 nm):  only binary collisions contribute - „snowplough effect“: first layers of ion bunch remove electrons of target foil - predominant part of bunch: screened from electrons (n e reduced)  reduction of dE/dx : avoids ion deceleration below V C :  allows for thick reaction targets for fusion reactions ELI-NP Workshop, Bucharest, March 10-12, 2011

7. Peter G. Thirolf, LMU München Exp. Scheme for “Fission-Fusion” collective stopping: ~ 1 mm Fission fragments Fusion products 232 Th: ~ 5 mm CD 2 : 520 nm 232 Th: 560 nm ELI-NP Workshop, Bucharest, March 10-12, 2011 Reaction targetProduction target APOLLON laser : 1.2. 10 23 W/cm 2 32 fs, 273 J,8.5 PW 1.0. 10 22 W/cm 2 32 fs, 23 J, 0.7 PW focus: ~ 3  m conventional stopping: ~ 1 mm Fission fragments Fusion products Reaction targetProduction target CD 2 : 520 nm CH 2 ~ 70  m 232 Th: ~ 50  m 232 Th: 560 nm APOLLON laser : 1.2. 10 23 W/cm 2 32 fs, 273 J, 8.5 PW 1.0. 10 22 W/cm 2 32 fs, 23 J, 0.7 PW focus: ~ 3  m

8. Peter G. Thirolf, LMU München Fission-Fusion Yield / Laser Pulse laser acceleration (300 J,  ~10%): normal stopping reduced stopping 232 Th 1.2. 10 11 1.2. 10 11 C 1.4. 10 11 1.4. 10 11 protons 2.8. 10 11 1.8. 10 11 beam-like light fragments 3.7. 10 8 1.2. 10 11 target-like light fragments 3.2. 10 6 1.2. 10 11 fusion probability 1.8. 10 -4 1.8. 10 -4 F L (beam) + F L (target) neutron-rich fusion products 1.5 4. 10 4 (A≈ 180-190)  laser development in progress: diode-pumped high-power lasers: increase of repetition rate expected ELI-NP Workshop, Bucharest, March 10-12, 2011

9. Peter G. Thirolf, LMU München Towards N=126 Waiting Point  r process path: - known isotopes ~15 neutrons away from r process path (Z≈ 70) 0.5 0.1 x  visions: - test predictions: r process branch to long-lived (~ 10 9 a) superheavies (Z≥110)  search in nature ? - improve formation predictions for U, Th - recycling of fission fragments in (many) r process loops ? - lifetime measurements: already with ~ 10 pps  measure: - masses, lifetimes, structure -  -delayed n emission prob. P,n 0.001  fisfus key nuclei ELI-NP Workshop, Bucharest, March 10-12, 2011

10. Peter G. Thirolf, LMU München Experimental layout high power short-pulse laser APOLLON (gas-filled) separator mirror target concrete shielding  characterization of reaction products - decay spectroscopy (tape) transport system detector ELI-NP Workshop, Bucharest, March 10-12, 2011

11. Peter G. Thirolf, LMU München Experimental layout high power short-pulse laser APOLLON (gas-filled) separator mirror target concrete shielding gas stopping cell cooler/buncher Penning trap mass measurements (  m/m= 10 -8 )  characterization of reaction products - decay spectroscopy  precision mass measurements: e.g. Penning trap ELI-NP Workshop, Bucharest, March 10-12, 2011

12. Peter G. Thirolf, LMU München “The Way Ahead” ELI-NP Workshop, Bucharest, March 10-12, 2011  exploratory experiments :  requirements: - RPA target chamber - 232 Th target development - ion diagnostics: Thomson parabola - staged approach with tests of crucial ingredients at existing facilities prior to operation of ELI-NP  laser ion acceleration of Th ions  collective effects of dense ion bunches (range enhancement)

13. Peter G. Thirolf, LMU München Conclusions  novel laser ion acceleration (RPA): - generation of ultra-dense ion bunches - enables fission-fusion reaction mechanism  fusion between 2 neutron-rich fission fragments - reduction of electronic stopping ? - may lead much closer towards N=126 r-process waiting point  ELI-NP: unique infrastructure - superior to ‘conventional’ radioactive beam facilities  The Way Ahead: - exploratory experiments at existing laser beams (Thorium acceleration, collective range enhancement..) - collaboration has to be formed ELI-NP Workshop, Bucharest, March 10-12, 2011

14. Peter G. Thirolf, LMU München Thanks to the Collaboration: D. Habs (LMU, MPQ) T. Tajima (LMU, JAEA/Kyoto) J. Schreiber (LMU) M. Gross (LMU) A.Henig (LMU) D. Jung (LMU) D. Kiefer (LMU) G. Korn (MPQ) F. Krausz (MPQ, LMU) J. Meyer-ter-Vehn (MPQ) H.-C. Wu (MPQ) X.Q. Yan (MPQ, Univ. Beijing) B. Hegelich (LANL, LMU) V. Liechtenstein (Kurchatov Inst., Moscow) Thank you for your attention ! ELI-NP Workshop, Bucharest, March 10-12, 2011

15. Peter G. Thirolf, LMU München Requirements for E1 @ ELI-NP: Floorspace layout ELI-NP Workshop, Bucharest, March 10-12, 2011 production- separation area measurement area concrete shielding 18 m 12 m 15 m recoil separator: - wide momentum acceptance - gas-filled ?

16. Peter G. Thirolf, LMU München Experimental Requirements @ ELI-NP 110 m 120 m ELI-NP Workshop, Bucharest, March 10-12, 2011 E1: laser-induced nuclear reactions  “fission-fusion” experimental areas Laser clean rooms

17. Peter G. Thirolf, LMU München Cost Estimate ELI-NP Workshop, Bucharest, March 10-12, 2011  component cost estimate: - laser target chamber: ~ 200 kEUR - recoil separator : ~ 5000 kEUR - tape station : ~ 150 kEUR - decay detectors : ~ 150 kEUR - buffer gas cell : ~ 300 kEUR - mass analyzer : ~ 300 kEUR - electronics, control, data acquisition : ~ 200 kEUR total: ~ 6.3 MEUR