RIKEN Accel. Prog. Rep. 47 (2014)

HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 47 (2014)

Structure study of 10 He by 11 Li(d,3 He) transfer reaction

All studies in which 10 He has been populated byproton removal from 11 Li and observed in invariantmass spectroscopy agree that E ∼ 1.2-1.6 MeV1–4) . Recently, the analysis of the missing-mass spectrum fromthe transfer reaction 8 He(t,p)10 He5) lead to a sizeably
higher value, E ∼ 2.1 MeV.
Our experiment, performed in July 2010 at theRIKEN RIPS facility, used a secondary beam of 11 Li
at 50 AMeV on a CD2 target. At forward angle, awall of four MUST2 telescopes6) were coupled withfour 20 µm thick silicon detectors in order to perform
an E-∆E identification of the light particles, and separation of 4 He and 3 He. At zero degree, a fifth MUST2
telescope and a two stages plastic detector were used
for identification of heavy residues of reaction in coincidences. In addition a 9 Li beam at 50 A.MeV wasused to perform a reference experiment populating theground state of 8 He.
The final excitation spectrum of the unbound 10 He,
reconstructed in coincidence with 8 He decay products(Fig.1), exhibits two clean resonances located respectively at 1.3(3) MeV and 6.3(6) MeV above the twoneutron threshold, with natural widths of 1.1(6) MeVand 2.7(7) MeV respectively. The associated differential cross sections have been extracted. They areabout one order of magnitude smaller than those predicted in standard DWBA calculations. The implication of this reduction and possible explanations, suchas the influences of different neutron binding energies,
are explored and put into perspective with the measured cross section of the 8 He ground state via the9Li(d,3 He) reaction.
The spectrum obtained in coincidence with the 6 He
decay products (Fig.1) is showing a preferred decay
to the 6 He+4n channel when possible. This could be∗1Institut de Physique Nucléaire, IN2P3-CNRS
Department of Physics, University of Surrey∗3 RIKEN Nishina Center∗4 CEA, Centre de Saclay, IRFU/Service de Physique Nuclaire∗5 LPC Caen, ENSICAEN, Universit de Caen, CNRS/IN2P3∗6 GANIL, CEA/DSM - CNRS/IN2P3∗7 IPNS,KEK∗8 Tokyo Institute of Technology,O-okayama,Tokyo∗9 Center of Nuclear Physics, Institute of Physics, Vietnam
Academy of Science and Technology∗10 National Research Centre “Kurchatov Institute”∗11 Departamento de FA, Universidad de Huelva∗12 Centro de Fı́sica Nuclear da Universidade de Lisboa∗13 Institute of Nuclear Physics PAS∗2- xxi -counts / 750 keV

A. Matta,∗1,∗2 D. Beaumel,∗1,∗3 H. Otsu,∗3 V. Lapoux,∗4 N.K. Timofeyuk,∗2 N. Aoi,∗3 M. Assie,∗1 H. Baba,∗3S. Boissinot,∗4 R. Chen,∗3 F. Delaunay,∗5 N. de Sereville,∗1 S. Franchoo,∗1 P. Gangnant,∗6 J. Gibelin,∗5F. Hammache,∗1 C. Houarner,∗6 N. Imai,∗7 N. Kobayashi,∗8 T. Kubo,∗3 Y. Kondo,∗8 Y. Kawada,∗8L.H. Khiem,∗9 M. Kurata-Nishimura,∗3 E.A. Kuzmin,∗10 J. Lee,∗3 J.F. Libin,∗6 T. Motobayashi,∗3T. Nakamura,∗8 L. Nalpas,∗4 E. Yu. Nikolskii,∗3,∗10 A. Obertelli,∗4 E.C. Pollacco,∗4 E. Rindel,∗1 Ph. Rosier,∗1
F. Saillant,∗6 T. Sako,∗8 H. Sakurai,∗3 A. Sanchez-Benitez,∗11,∗12 J-A. Scarpaci,∗1 I. Stefan,∗1 D. Suzuki,∗1K. Takahashi,∗8 M. Takechi,∗3 S. Takeuchi,∗3 H .Wang,∗3 R. Wolski,∗13 K. Yoneda∗35432

10-202468101214

E10He (MeV)
Fig. 1. The 10 He spectrum measured from 11 Li(d,3 He) reaction data in coincidences between 3 He and 8 He (solidblue) and 6 He (dashed orange). The two vertical dashedlines indicate the positions of the 6 He+4n and 4 He+6nthresholds.

inferred to the important role played by the 8 He(2+)
excited state in the 10 He structure, arguing for the development of models beyond the three-body approach.
References
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