Eur. Phys. J. Special Topics 150, 23-26 (2007)
https://doi.org/10.1140/epjst/e2007-00256-x

Properties of low-lying ⁹He state

¹ Flerov Laboratory of Nuclear Reactions, JINR, 141980 Dubna, Russia
² The Henryk Niewodniczański Institute of Nuclear Physics, Kraków, Poland
³ RIKEN, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
⁴ RRC “The Kurchatov Institute”, Kurchatov sq. 1, 123182 Moscow, Russia
⁵ Institut de Physique Nucléaire, IN2P3-CNRS, 91406 Orsay, France
⁶ GANIL, BP. 5027, 14076 Caen Cedex 5, France

Received: 31 January 2007
Published online: 8 December 2007

Abstract

The spectrum of ⁹He was studied by means of the ⁸He(d,p)⁹He reaction at a lab energy of 25 MeV/n and small center of mass (c.m.) angles. Energy and angular correlations were obtained for the ⁹He decay products by complete kinematical reconstruction. The data analysis was done in the assumption of a direct one-neutron transfer reaction mechanism. The ⁹He structure was analysed in the framework of a simple single-particle model. The lowest resonant state of ⁹He is found at about 2 MeV with a width of ∼2MeV and is identified as 1/2^-. The observed angular correlation pattern is uniquely explained by the interference of the 1/2^- resonance with a virtual state 1/2⁺ (a limit on the scattering length is obtained as a > -20fm), and with a 5/2⁺ resonance at energy ≥4.2MeV.