Be low-lying states *

 

 

 

The Be isotopic chain has been essential for understanding the breakdown of N=8. The disappearance of N = 8 magic number is, among other things, evidenced by the presence of a low-lying isomeric state 0⁺ at 2.24 MeV in ¹²Be. A recent one-neutron transfer reaction applied an isomer-tagging and obtained the s-wave component ~39% for the 0⁺₂ state while only ~19% for the g.s. In order to directly measure the spectroscopic factor of the 0₂⁺ state in ¹²Be, a new measurement of ¹¹Be(d,p)¹²Be reaction has been proposed using ISOLDE Solenoid Spectrometer (ISS) at CERN, taking advantage of its excellent resolution to isolate the 0₂⁺ and 2⁺ doublet. To determine the evolution of the s1/2, p1/2 and d5/2 single-particle energies, and to investigate the contribution of the core excitation component, an experiment was proposed to study the structure of the low-lying states of ¹³Be using a (d,p) reaction on a ¹²Be beam containing both its ground and isomeric states. The measurement will be carried out at the RCNP, using the active target time projection chamber (AT-TPC) from NSCL, Michigan State University.