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Nuclear break-up of exotic nuclei

Nuclear break-up of exotic nuclei. I History of the towing mode in stable nuclei the 40 Ar+ 58 Ni @ 40 MeV/A case II The TDSE calculation III The case of the 11 Be break-up IV The extension to borromean nuclei V Conclusions - Perspectives. J a s s.

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Nuclear break-up of exotic nuclei

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  1. Nuclear break-up of exotic nuclei • I History of the towing mode in stable nuclei • the 40Ar+58Ni @ 40 MeV/A case • II The TDSE calculation • III The case of the 11Be break-up • IV The extension to borromean nuclei • V Conclusions - Perspectives Jass

  2. Inelastic Channel-projectile=ejectile A A A A A Target A+1 Projectile A A A A Inelastic Scattering GR and multiphonons Knock Out Pick-up Break-up New mechanism? 1 emitted particle Jass 1 or several emitted particle(s)

  3. 40Ar qlab p or n 58Ni Feeding of the first hole states of the daughter nucleus 40Ar Angular distribution of nucleon emitted in 58Ni(40Ar, 40Ar + n or p) Jass

  4. Action F 0 r 0 r 0 r 0 r F 0 r t Jass

  5. What happens when a force acts on a mass for a given period of time ? Action .. m F F = m.x x . xo = 0 . x = d  (ro . A1/3)= 4 fm d E ~ 40 MeV/A tc = vp vp= 10+23 fm.s-1 . . F x = . tc + xo tc = 4. 10-23 s m F = 15 MeV.fm-1 3 fm 15 . 9 . 10+46 .4. 10-23 = 6.10+22 fm.s-1 900 Right order of magnitude! Jass

  6. Nuclear break-up of exotic nuclei • I History of the towing mode in stable nuclei • the 40Ar+58Ni @ 40 MeV/A case • II The TDSE calculation • III The case of the 11Be break-up • IV The extension to borromean nuclei • V Conclusions - Perspectives Jass

  7. 2 p U 0 2. m - r 0 1+ e a 0 Time dependent solutions ^ proj target 2 U U p proj 0 0 H = + + target 0(t)) ( r ( r - r (t)) 2. m - r 0 1+ e 1+ e a a 0 0 ^ FFT of (x,t) d i Hdt  = H   ( t + dt ) =  ( t ) i h - e h d t Split operator . . . and Evolution of a one-particle wave function via the resolution of time dependent Schrödinger J.A. S. D. Lacroix Ph. Chomaz ^ Static solutions H = + ( r ) H  = .  diagonalization eigen states, eigen values Exact up to 2sd order Jass D.Lacroix et al. Nucl. Phys. A658 (1999) p273

  8. Resolution of time dependent Schrödinger equation on a mesh non perturbative calculation • The calculation includes : • TDSE for a wave function in a moving potential • diffraction (refraction!) through the nuclear potential • single particle excitations to unbound states • n-core excitations (!!) • « shaking  » of the core (Coulomb classical trajectory) proj target proj • The calculation does not include : • spin-orbit, pairing • No structure info • core or target excitations (not excluded either) • nucleon-nucleon dissipation • quantum relative motion • energy conservation target Jass

  9. Towing Mode Projectile WS Einc = 44 MeV/A Target WS Evolution of a wave function via the resolution of time dependent Schrödinger t = 0 t = 130 fm/c Initial wave function Jass

  10. y x Same density probability after subtraction of the bound eigen states y Initial Density Probability in the target potential at rest in the lab frame. Evolution x Density probablility after the projectile has passed FFT py ds/dW (q) Fourier transform of the former density probability. px Jass Angular distribution of the emitted particle

  11. 40Ar 58Ni b=10 fm 58Ni(40Ar,40Ar+p or n) 2p calculation, b from 10 to 12 fm Plus flat background ~50° py ~50° 2s px Jass

  12. Nuclear break-up of exotic nuclei • I History of the towing mode in stable nuclei • the 40Ar+58Ni @ 40 MeV/A case • II The TDSE calculation • III The case of the 11Be break-up • IV The extension to borromean nuclei • V Conclusions - Perspectives Jass

  13. 11Be break-up calculations WS potential to bound the 2s by 0.5 MeV Density of 2s 2000 13 fm Does not change when using N.Vinh Mau potential 80 15 1 Need to use a Coulomb trajectory : Weakly bound neutron Large Coulomb break up Runge Kuttar(t+dt) = r(t-dt) + 2.dt.p(t)/m p(t) = p(t-2dt) + 2.dt.F(t-dt)/m Imaginary time evolution extract a stable eigen state (M.Fallot...) for the cartesian mesh Jass Interpolation ...

  14. Neutron angular distributions Au,Ti,Be (11Be, 10Be + n) @ 41 Mev/A Data from : R.Anne et al.,Nucl.Phys. A575 (1994) 125 lab lab lab neutron neutron neutron M.Fallot, J.A.Scarpaci, D.Lacroix, Ph. Chomaz et J.Margueron, Nuclear Physics A700 (2002) 70 Large b (Coulomb break-up) = forward peaked emitted neutron Small b (nuclear break-up) = responsible for neutrons emitted at large angle The nuclear break-up is fully reproduced by the interaction of the particle with the mean field of the target - no need of n-n interaction…. Jass

  15. 11Be a halo nucleus n • Neutron bound by 0.504 MeV • GS (Jp =1/2+): • |GS>= a|2s1/2 0+> + b |1d5/2 2+> 10Be a2 (S2s) et b2 (S1d): spectroscopic factors 10Be 2+ state of b2=0.74 Ref: Auton et al. NP A 322(1970) 305 g Eg=3.37 MeV Jass

  16. GANIL SISSI • Primary beam of 13C @ 75 A.MeV • Secondary beam of 80000 11Be/s @ 41 A.MeV. SPEG Jass

  17. Experimental set-up & results Experimental set-up Neutron angular spectra n-detectors 48Ti 11Be 10Be + n +  @ 41 MeV/A  Our data 11Be Château de cristal 3m 10Be SPEG qlab 1994 data from R.Anne et al., Nucl. Phys. A575 (1994) 125. TDSE calculations M.Fallot et al., Nucl. Phys. A 700 (2001) 70-82. 48Ti 10Be TDSE Calculation Jass

  18. Experimental set-up & results Neutron energy spectra no- S2s = 0,47± 0,04 n-detectors TDSE calc. 2s 48Ti 11Be 10Be + n +  @ 41 MeV/A  11Be Château de cristal 3m incoincidence 10Be S1d= 0,50 ± 0,20 S1p= 3.9 SPEG 4*1p 48Ti 0.5*1d 10Be V.Lima et al., Bormio 2004 V.Lima, Ph.D. Paris XI, oct 2004 V.Lima et al., in preparation TDSE Calculation Jass

  19. The G.S. of 11Be |GS> ~ a |2s1/2  0+> + b |1d5/2  2+> S2s ≈ 85-36% S1d ≈ ?% Transfer reactionp(11Be,10Be)d: GANIL Fortier et al.,PL B 461(1999)22-27 Break-up reactions (11Be,10Be) @ 60 MeV/u and eikonal models T. Aumann et al., P.R.L.84 (2000) 35-38 Break-up reactions (11Be,10Be) @ 520 MeV/u Palit et al., PR. C 68, 034318 (2003) nucl. DWBA excitation and break-up Large diversity of S2s elect. B.Zwieglinski et al. Nucl.Phys.A315, 124 (1979) N.K.Timofeyuk et al. P.R.C59, 1545 (1999) Our work

  20. Nuclear break-up of exotic nuclei • I History of the towing mode in stable nuclei • the 40Ar+58Ni @ 40 MeV/A case • II The TDSE calculation • III The case of the 11Be break-up • IV The extension to borromean nuclei • V Conclusions - Perspectives Jass

  21. Study of neutron correlationswith nuclear break-up 6He is an archetype of a Borromean nucleus ; high intensities most suitable nucleus to investigate new experimental approach and develop new theoretical tools Di-neutron configuration Cigar configuration Zhukov et al., Phys. Rep. 231 (1993) 151 three-body description expansions on hyperspherical harmonics coordinate space Faddeev approach Jass

  22. Some experiments on 6He… • Transfer reactions4He( 6He,6He) 4He • dominated by di-neutron conf… • Yu.Oganessian et al. (1999) : Dao T.Khoa and W.von Oertzen (2004) • Radiative capture 6He(p,)x @ 40 MeV/A - no  + t decay • large distance between the two neutrons… (cigar like) • E.Sauvan et al. (2001) • Coulomb break-up6He + C, Pb @ 30-60 MeV/A • large distance between the two neutrons… (cigar like) • Invariant mass ≠ interferometry … depending on impact parameter cuts… • G.Normand et al. (2004) rn-n 7.7 fm, 9.4 fm • F.M.Marques et al. (2000) rn-n 5.9 fm • @ 240 MeV/A 6,8He + Pb @ 700 MeV/A • L.V.Chulkov et al. (2005) QFS dominates • low lying 1- states 3-6 MeV  core plus 2 or 4 neutrons • 8He = small 6He + 2n No consensus on the n-n configuration Open to more experiments Jass

  23. d/d Large impact parameters Coulomb break-up Small impact parameters Nuclear break-up cigar di-neutron cigar di-neutron n d/d Small differences in relative angles di-neutron cigar n 0° 60° Measure neutrons at large angles Needs a theoretical development 0° 60° Neutron angular emission extension of TDHF (TDDM) (M.Assie-D.Lacroix) Jass G.Normand, PhD thesis 2004 F.M.Marques, PR C64, 2001

  24. Set-up High neutron angular coverage up to 90° : neutron wall + 20 additional detectors Si detector for 4He covering from 5° to 15° Additional neutron detectors n Faraday cup 4He 6He 20 MeV/u 5 mg/cm2 Pb target Si det. n 65° Neutron wall

  25. Nuclear break-up of exotic nuclei • I History of the towing mode in stable nuclei • the 40Ar+58Ni @ 40 MeV/A case • II The TDSE calculation • III The case of the 11Be break-up • IV The extension to borromean nuclei • V Conclusions - Perspectives • Reaction mechanism plays an important role in the break-up • towing Mode, a spectroscopic tool • need of good theoretical description to infer spectroscopic factors • Development required for two-particle wave function evolution • extension of TDHF - Marlène Assié, Denis Lacroix • Possible application to cluster studies! • observation of  emission in 40Ca break-up Jass

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