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Study of Neutron Transfer and Resonant Scattering induced by 11Li with MAYA Active Target

This study focuses on investigating neutron transfer reactions and resonant elastic scattering induced by 11Li using the MAYA active target. The motivations, experimental setup, and possible experiments at ISOLDE are discussed. Results and conclusions from previous studies are also presented.

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Study of Neutron Transfer and Resonant Scattering induced by 11Li with MAYA Active Target

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  1. Study of two neutron transfer reaction and resonant elastic scattering induced by 11Li, with the MAYA active target.

  2. Outline • MAYA@TRIUMF : Transfer & resonant reactions with 11Li • Motivations • The active target MAYA • The TRIUMF experiment • MAYA@ISOLDE : Possible experiments • Technical issues • Possibilities

  3. Motivations Experimental setup Results Conclusion MAYA@ISOLDE • Halo occurrence condition(s)‏ •  low binding energy • low angular momentum (1)‏ • N=7 parity inversion • 10Li (G.S.) : s-state (2)‏ • s-p mixing in 11Li (3)‏ • 11Li coulomb dissociation  strong correlations (1) K. Riisager et al., Nucl. Phys. A548, 393 (1992)‏ (2) H. Simon et. al., Nucl. Phys. A791, 267 (2007)‏ (3) H. Simon et. al., Phys. Rev. Lett. 83, 496 (1999)‏ (4) T. Nakamura et. al., Phys. Rev. Lett. 96, 252502 (2006)‏

  4. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Reactions with losely bound nucleus at low energy  Couplings! N. Keeley and V. Lapoux, Phys. Rev. Lett. 77, 014605 (2008) A. Lemasson et al., accepted in Phys Rev. C Study of “low energy” reactions induced by 11Li on a proton target - 2 neutron transfer reaction.  angular distribution : strength of the correlation - 1 neutron transfer reaction.  angular distribution : spectroscopy of the halo. - Elastic scattering.  angular distribution : density distribution - Resonant elastic scattering.  excitation function : 12Li Isobaric Analog States

  5. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Study of “low energy” reactions induced by 11Li on a proton target - 2 neutron transfer reaction.  angular distribution : strength of the correlation - 1 neutron transfer reaction.  angular distribution : spectroscopy of the halo. - Elastic scattering.  angular distribution : density distribution - Resonant elastic scattering.  excitation function : 12Li Isobaric Analog States Good angular coverage + Thick target Active target (detection/ reaction )‏

  6. Motivations Experimental setup Results Conclusion MAYA@ISOLDE ISAC II  up to 5000 pps 11Li @ 5A MeV 0° beamline with PPAC detector and the active target MAYA

  7. Motivations Experimental setup Results Conclusion MAYA@ISOLDE C.E. Demonchy et al., Nucl. Instrum . Methods A 573, 145 (2007)‏

  8. Motivations Experimental setup Results Conclusion MAYA@ISOLDE A two dimensional charge – one dimensional time projection chamber Cathode recorded pattern  2 dimensions Wire recorded time  3rd dimension

  9. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Light particles + high energy  Si / CsI Medium energy  PADS / Si 2 solid identification stages + 1 gaseous stage  Large identification dynamics!

  10. Motivations Experimental setup Results Conclusion MAYA@ISOLDE YMAYA (mm) 160 80 0 90 180 Depth (mm) • Charge distribution : “ The recorded charge distribution is the result of the convolution • of the charge distribution created by a point-source and the hexagonal geometry • of the pads, all along the charged particles tracks and weighted by their energy losses. ”  A simulation is necessary to develop the reconstruction algorithms and to estimate the geometric efficiency

  11. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Two experiments – Two setups “Thin” target : fixed energy (150mbar - 1.7 mg/cm2)‏  angular distributions angle-angle correlations “Thick” target : fixed c.m. angle (670 mbar – 7.6 mg/cm2)‏  excitation functions energy-energy correlations

  12. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Mass measurement by Q-value measurement : 1H(11Li,9Li)t corrélations angle-angle corrélations énergie-énergie  S2n (11Li) = 363(22) keV T. Roger et al., Phys. Rev. C 79, 031603(R) (2009)  Can be extended to unbound nuclei

  13. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Angular distribution @ 4.3A MeV • Very close to Rutherford •  unusual behavior (qgrazing = 10°) - Global Optical Potentials : Fail! Need to increase Wd et diminish awd  Surface peaked absorption! (breakup + transfer, compound nucleus)

  14. Motivations Experimental setup Results Conclusion MAYA@ISOLDE 3A MeV 4.3A MeV  DWBA/CRC calculation required • transitions to 9Li (GS) & 9Li* (2.69 MeV)

  15. Motivations Experimental setup Results Conclusion MAYA@ISOLDE p sequential s 10Li 9Li (g.s.) 11Li: s2 & p2 simultaneous 3A MeV 4.3A MeV CCBA calculations (I.J. Thompson) I.J. Thompson et al. (Phys. Rev. C 49, 1904 (1994))  Configuration mixing! I. Tanihataet al., Phys. Rev. Lett. 100, 192502 (2008)

  16. Motivations Experimental setup Results Conclusion MAYA@ISOLDE • Angular distribution @ 4.3A MeV (integrated over 10Li states)  Contribution of 9Li(cont.) (minor)  CRC calculation needed!  Hard to identify the populated state

  17. Motivations Experimental setup Results Conclusion MAYA@ISOLDE • Kinematics reconstruction with • the energy/energy (range) correlations VERTEX TOTAL PATH BEAM HEAVY VERTEX TOTAL PATH

  18. Motivations Experimental setup Results Conclusion MAYA@ISOLDE 150° cm 175° cm • Possible IAS of 12Li (T=3 state observed in 12Be: Charity et al.) R.J. Charity et al., Phys. Rev. C 76, 064313 (2007) R matrix calculation to assign a spin • Resonance @ Ecm ≈ 3 MeV

  19. Motivations Experimental setup Results Conclusion MAYA@ISOLDE VB R-Matrix calculations • E < 2MeV  Rutherford • Hard sphere phase shifts  Cross section too high  1 level approximation not valid •  Complex phase shifts • 11Li+p optical potential needed!  All the processes are interconnected!

  20. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Er = 3.0 MeV Gtot = 1.1 MeV Breit Wigner fit: Incoherent sum of Coulomb et BW

  21. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Gsp @ 3 MeV: l = 0 : 7.58 MeV l = 1 : 5.28 MeV l = 2 : 1.91 MeV s state with S = 0.14 d state with S = 0.57 d state compatible with CXMSM calculations (Z.X Xu et al. submitted to Phys. Rev. C) No positive parity states below 6.5 MeV (E*=3.5 MeV) B.A. Brown, Private Communication Er = 3.0 MeV Gtot = 1.1 MeV Y. Aksyutina : s state @ 1.5 MeV Our result: Y. Aksyutinaet al., Phys. Lett. B 666, 430 (2008) + =

  22. Motivations Experimental setup Results Conclusion MAYA@ISOLDE • - ideal study with active targets • ideal case for Coupled Reaction Channel calculations Complete study • Elastic scattering angular distribution. •  ≈ Rutherford up to 90° cm: coupling to transfer and breakup channels • 1n and 2n transfer angular distributions @ 3A and 4.3A MeV •  First calculations indicate a strong correlation between the halo-neutrons • + Mass of 11Li by Q-value measurement • 11Li(p,p)11Li excitation function at 150° and 175° cm •  possible T=3 state in 12Be  Interconnected processes! Need global treatment with CRC & CDCC

  23. MAYA@TRIUMF Collaborators T. Roger , H. Savajols, M. Caamaño, P. Roussel-Chomaz GANIL, Bd Henri Becquerel, BP 55027, 14076 Caen Cedex 05, France W. Mittig and H. Wang NSCL, MSU, East Lansing, MI 48824-1321, USA I. Tanihata, M. Alcorta, D. Bandyopadhyay, R. Bieri, L. Buchmann, B. Davids, N. Galinski, D. Howell, W. Mills, R. Openshaw, E. Padilla-Rodal, G. Ruprecht, G. Sheffer, A. C. Shotter, M. Subramanian, M. Trinczek, and P. Walden TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada R. Kanungo and A. Gallant Saint Mary’s University, 923 Robie St., Halifax, Nova Scotia B3H 3C3, Canada M. Notani and G. Savard ANL, 9700 S. Cass Ave., Argonne, IL 60439, USA I. J. Thompson LLNL, L-414, P.O. Box 808, Livermore CA 94551, USA ++ MAYA’s Technical Staff as : J.F. Libin, P. Gangnant, C. Spitaels, L. Olivier & G. Lebertre

  24. MAYA@ISOLDE: possible experiments

  25. Motivations Experimental setup Results Conclusion MAYA@ISOLDE - MAYA: slow gazeous detector - MAYA dynamics from p(11Li,9Li)t @ 4.3A MeV – 150 mbar C4H10 CM = 35° E9Li = 53.9 MeV Et = 1.4 MeV <dE/dx>9Li = 26 keV/mm CM = 145° E9Li = 19.1 MeV Et = 36.3 MeV <dE/dx>t = 1.5 keV/mm  Pile-up above 1 ion/10 µs  Dynamics ≈ 20 Upgrade of GASSIPEX : threshold 100 mV  30 mV

  26. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Possible solution : mask the beam Transparency tunable (0 – 10%)  Artificially increases the dynamics E.Kahn, J.Gibelin E548a (GANIL): 68Ni(d,d’)  dynamics ≈ 100

  27. Motivations Experimental setup Results Conclusion MAYA@ISOLDE Pulsed beam from EBIS : Instantaneous maximum intensity!  if Ipps>103 : on1 µs Imax ≈ 103 Ipps • If the beam track is needed: (resonant reaction, precise transfer reactions) •  limited to 102 – 103 pps • Else: theoretically no restriction BUT: • 132Sn beam @ 105 pps into150 mbar C4H10 : 1.7x107 e- /mm/1µs •  Very close to the sparking limit…

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