peter g. thirolf, lmu münchen the ‘fission–fusion‘ reaction mechanism: using dense...
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Peter G. Thirolf, LMU München
The ‘Fission–Fusion‘ Reaction Mechanism:The ‘Fission–Fusion‘ Reaction Mechanism:Using dense laser-driven ion beamsUsing dense laser-driven ion beams
for nuclear astrophysicsfor 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
Peter G. Thirolf, LMU München
r process: waiting point r process: waiting point N=126N=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
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: 1022 - 1023 e/cm3
‘classical’ bunches: 108 e/cm3
Radiation Pressure AccelerationRadiation Pressure Acceleration
driver laser
ions electronsnmfoil
relativ. electrons at solid density
~ 1014 x density of conventionally accelerated ion beams
ELI-NP Workshop, Bucharest, March 10-12, 2011
Peter G. Thirolf, LMU München
Exp. Scheme for “Fission-Exp. Scheme for “Fission-Fusion” Fusion”
ELI-NP Workshop, Bucharest, March 10-12, 2011
~ 1 mm Fission fragments
Fusion products
Reaction targetProduction target
CD2: 520 nm
CH2 ~ 70 m
232Th: ~ 50m 232Th: 560 nm
APOLLON laser :
1.2.1023 W/cm2
32 fs, 273 J, 8.5 PW
1.0.1022 W/cm2
32 fs, 23 J, 0.7 PW
focus: ~ 3 m
232Th + p, C → FL + FH : beam-like fission fragments
beam (~ 7 MeV/u): d, C, 232Thtarget: p, C, 232Th
d, C + 232Th → FL + FH : target-like fission fragments
D. Habs, PT et al., Appl. Phys. B, in print
Peter G. Thirolf, LMU München
Fission Stage of Reaction Fission Stage of Reaction Scheme Scheme
232Th:<AL> ~ 91, AL ~ 14 amu (FWHM) AL ~ 22 amu (10%)<ZL> ~ 37.5 (Rb,Sr)
FL FH
fission mass distribution:
ELI-NP Workshop, Bucharest, March 10-12, 2011
fusion-evaporation calculations (PACE4): (Z=35,A=102) + (Z=35, A=102): Elab= 270 MeV (E* = 65 MeV) 190Yb (Z=70,N=126): 2.1 mb 189Yb ( N=125): 15.8 mb 188Yb ( N=124): 61.7 mb 187Yb ( N=123): 55.6 mb
Peter G. Thirolf, LMU München
Collective Stopping Power Collective Stopping Power ReductionReduction
p
D
D
e
e
e
vk
ke
vm
vm
eZn
dx
dE
lnln4
2
2
2
42eff
binary collisionskD = Debye wave number
long-range collective interactionp = 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 (ne reduced)
reduction of dE/dx : avoids ion deceleration below VC:
allows for thick reaction targets for fusion reactions
ELI-NP Workshop, Bucharest, March 10-12, 2011
Peter G. Thirolf, LMU München
Exp. Scheme for “Fission-Exp. Scheme for “Fission-Fusion” Fusion”
collective stopping:
~ 1 mm Fission fragments
Fusion products
232Th: ~ 5 mm
CD2: 520 nm
232Th: 560 nm
ELI-NP Workshop, Bucharest, March 10-12, 2011
Reaction targetProduction target
APOLLON laser :
1.2.1023 W/cm2
32 fs, 273 J,8.5 PW
1.0.1022 W/cm2
32 fs, 23 J, 0.7 PW
focus: ~ 3 m
conventional stopping:
~ 1 mm Fission fragments
Fusion products
Reaction targetProduction target
CD2: 520 nm CH2 ~ 70 m
232Th: ~ 50m 232Th: 560 nm
APOLLON laser :
1.2.1023 W/cm2
32 fs, 273 J, 8.5 PW
1.0.1022 W/cm2
32 fs, 23 J, 0.7 PW
focus: ~ 3 m
Peter G. Thirolf, LMU München
Fission-Fusion Yield / Laser Fission-Fusion Yield / Laser PulsePulse
laser acceleration (300 J, ~10%): normal stopping reduced stopping
232Th 1.2 . 1011 1.2 . 1011
C 1.4 . 1011 1.4 . 1011
protons 2.8 . 1011 1.8 . 1011
beam-like light fragments 3.7 . 108 1.2 . 1011
target-like light fragments 3.2 . 106 1.2 . 1011
fusion probability 1.8 . 10-4 1.8 . 10-4
FL(beam) + FL (target)
neutron-rich fusion products 1.5 4 . 104
(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
Peter G. Thirolf, LMU München
Towards N=126 Waiting Towards N=126 Waiting PointPoint
r process path: - known isotopes ~15 neutrons away from r process path (Z≈ 70)
0.5 0.1x
visions:- test predictions: r process branch to long-lived (~ 109 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
0.001fisfus
key nuclei
ELI-NP Workshop, Bucharest, March 10-12, 2011
Peter G. Thirolf, LMU München
Experimental layoutExperimental layout
high powershort-pulselaser APOLLON
(gas-filled) separator
mirrortarget
concreteshielding
characterization of reaction products - decay spectroscopy
(tape) transport system
detector
ELI-NP Workshop, Bucharest, March 10-12, 2011
Peter G. Thirolf, LMU München
Experimental layoutExperimental layout
high powershort-pulselaser APOLLON
(gas-filled) separator
mirrortarget
concreteshielding
gas stopping cellcooler/buncher
Penning trapmass 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
Peter G. Thirolf, LMU München
““The Way Ahead”The Way Ahead”
ELI-NP Workshop, Bucharest, March 10-12, 2011
exploratory experiments :
requirements:
- RPA target chamber - 232Th 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)
Peter G. Thirolf, LMU München
ConclusionsConclusions
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
Peter G. Thirolf, LMU München
Thanks to the Collaboration: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 !Thank you for your attention !ELI-NP Workshop, Bucharest, March 10-12, 2011
Peter G. Thirolf, LMU München
Requirements for E1 @ ELI-NP:Requirements for E1 @ ELI-NP:Floorspace layoutFloorspace layout
ELI-NP Workshop, Bucharest, March 10-12, 2011
production- separation area
measurement area
concrete shielding
18 m
12 m
12 m
15 m
recoil separator:- wide momentum acceptance- gas-filled ?
Peter G. Thirolf, LMU München
Experimental Requirements @ ELI-NPExperimental Requirements @ ELI-NP
110 m
12
0 m
ELI-NP Workshop, Bucharest, March 10-12, 2011
E1:laser-induced nuclear reactions
“fission-fusion”
experimental areas
Laser clean rooms
Peter G. Thirolf, LMU München
Cost EstimateCost 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