1. Three-body correlations as a key to the structure of light unbound nuclei
Yuliya Aksyutina
for the LAND-R3B collaboration
Motivation
Experimental setup
Relative-energy spectra
Three-body correlations
Summary and outlook
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2. Nordic Winter Meeting on Physics @ FAIR
Motivation
Light nuclei:
ab initio calculations are available
Benchmark experiments:
extreme combinations of nucleons
Few-body systems:
clustering plays an important role
simplified modelling
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3. Region of interest: near and beyond the dripline
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4. Heavy-ion beam facility at GSI
E(8He) = 240 MeV/u
E(11Li) = 280 MeV/u
E(11Li) = 280 MeV/u
E(14Be)= 305 MeV/u
18O(308 MeV/u)
18O(360 MeV/u)
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5. Experimental setup Target: liq. Hydrogen, 350 mg/cm2
S2n(11Li) = MeV
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6. Nordic Winter Meeting on Physics @ FAIR
Observables
(x,y,z) → (θ,φ)
four-momentum => correlations
ToF → velocity
Relative energy: => positions, widths
of resonances
where − four-momentum,
− rest masses of reaction products.
check 4-momenta
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Quasi-free scattering on a nucleon inside halo nucleus (valence nucleon knockout )
Small binding energy [ < 1 MeV ]
Remaining system is a spectator
Core + n in the final state
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8. Neutron knockout from 11Li -> 10Li
a = −30+12 fm
Er = 0.510(44) MeV, Γ = 0.54(16) MeV
Er = 1.486(88) MeV, Γ<2.2 MeV
−31
a = −22(5) fm, S2n(fit) = 0.352(22) MeV
S2n(11Li) = MeV
Er = 0.566(14) MeV, Γ=0.548(30) MeV
H. Simon, M. Meister et al.,
Nucl. Phys. A 791 (2007) 267
Yu. Aksyutina, H.T. Johansson et al.,
Phys. Lett. B 666 (2008) 430
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9. Nordic Winter Meeting on Physics @ FAIR
Quasi-free scattering on a nucleon inside halo nucleus (nucleon knockout from core)
Proton strongly bound [ ~20 MeV ]
Remaining system cannot always be
considered as spectator
Core + n or core + 2n in the final state
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10. Proton knockout from 11Li -> 9He
a = -3.16(78) fm, S2n(fit) = 0.79(10) MeV
S2n(11Li) = MeV
S2n(8He) = MeV – momentum transfer to the core is probable!
Er = 1.33(8) MeV, G = 0.1* MeV
Er = 2.4* MeV, G = 0.7* MeV
*H.G. Bohlen et al.,
Prog. Part. Nucl. Phys. 42 (1999) 17
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11. Proton knockout from 11Li -> 10He
Er = 1.42(10) MeV, G = 1.04(76) MeV
Er = 1.54(11) MeV, G = 1.91(41) MeV
Er = 3.99(26) MeV, G = 1.64(89) MeV
Correlated background:
C. Forssén et al., Nucl. Phys.
A673 (2000) 143
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12. Proton knockout from 14Be
S2n(11Li) = MeV – in case of significant momentum transfer would decay
Er = 1.55(24) MeV, Γ = 1÷3 MeV
Correlated background:
C. Forssén et al., Nucl. Phys. A673 (2000) 143
a = -13.7(1.6) fm
S2n(fit) = 1.47(19) MeV
S2n(14Be) = 1.26(13) MeV
Yu. Aksyutina, H.T. Johansson et al.,
Phys. Lett. B 666 (2008) 430
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13. Angular correlations, 2-body case
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14. 3-body system, Jacobi coordinates
T-system
Hyperradius:
Hyperangle:
Y-system
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15. Angular correlations, 3-body case
Hypermomentum operator:
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Jacobi coordinates
T-system
(Jacobi momenta)
Hyperradius:
Hyperangle:
Partial energy:
Y-system
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Correlation function
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18. Hyperspherical harmonics
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19. Relative-energy spectrum of 10He
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Energy and angular correlations in 8He+n+n system, 0 < ECnn < 3 MeV
11Li*
Fit
Ip = 0+
*N.B.Shulgina, B.Jonson, M.V.Zhukov,
Nucl. Phys. A825 (2009) 175
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21. Relative-energy spectrum of 10He
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22. Nordic Winter Meeting on Physics @ FAIR
Energy and angular correlations in 8He+n+n system, 3 < ECnn < 7 MeV
11Li*
Fit
Ip = 2+
*N.B.Shulgina, B.Jonson, M.V.Zhukov,
Nucl. Phys. A825 (2009) 175
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23. Final interpretation of the 10He spectrum0+ 2+
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24. Relative-energy spectrum of 13Li
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25. Nordic Winter Meeting on Physics @ FAIR
Energy and angular correlations in 11Li+n+n system, 0 < ECnn < 3 MeV
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26. Relative-energy spectrum of 13Li
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Energy and angular correlations in 11Li+n+n system, 3 < ECnn < 7 MeV
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28. Nordic Winter Meeting on Physics @ FAIR
Summary
Spectroscopy of exotic nuclear systems 9,10He and 12,13Li was performed after proton knockout from halo nuclei 11Li and 14Be:
12,13Li were observed for the first time!
The position of the ground state of 10He is in agreement with small absolute value for the scattering length in 9He
Three-body correlations in 8He+n+n and 11Li+n+n systems were analyzed using hyperspherical harmonics formalism:
In both cases experimental distributions are determined by the final state interaction
Correlations in 10He were used to determine the quantum numbers of the ground and excited states
Correlations in 13Li give an indication of several overlapping resonances in the obtained 13Li relative-energy spectrum
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29. Nordic Winter Meeting on Physics @ FAIR
The future - R3B setup
Reactions with Relativistic Radioactive Beams
12m
30m
Reactions involving emission of projectile-like neutrons → high-energy neutron detector (300 MeV – 1 GeV)
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