A. Navin

Isotopic Yield Distributions of Transfer- and Fusion-Induced Fission from 238U+12C Reactions in Inverse Kinematics

A novel method to access the complete identification in atomic number Z and mass A of fragments produced in low-energy fission of actinides is presented. This method, based on the use of multi- nucleon transfer and fusion reactions in inverse kinematics, is applied in this work to reactions between a 238U beam and a 12C target to produce and induce fission of moderately excited actinides. The fission fragments are detected and fully identified with the VAMOS spectrometer of GANIL, allowing the measurement of fragment yields of several hundreds of isotopes in a range between A ~ 80 and ~ 160, and from Z ~ 30 to ~ 64. For the first time, complete isotopic yield distributions of fragments from well-defined fissioning systems are available. Together with the precise measurement of the fragment emission angles and velocities, this technique gives further insight into the nuclear-fission process.

Nucleus

The unbound nucleus ^{26}O has been investigated using invariant-mass spectroscopy following one-proton removal reaction from a ^{27}F beam at 201  MeV/nucleon. The decay products, ^{24}O and two neutrons, were detected in coincidence using the newly commissioned SAMURAI spectrometer at the RIKEN Radioactive Isotope Beam Factory. The ^{26}O ground-state resonance was found to lie only 18±3(stat)±4(syst)  keV above threshold. In addition, a higher lying level, which is most likely the first 2^{+} state, was observed for the first time at 1.28_{-0.08}^{+0.11}  MeV above threshold. Comparison with theoretical predictions suggests that three-nucleon forces, pf-shell intruder configurations, and the continuum are key elements to understanding the structure of the most neutron-rich oxygen isotopes beyond the drip line.

^{26}

The reaction cross section (

O : A Barely Unbound System beyond the Drip Line

\sigma_R

Reaction Cross Section Of The Two-neutron Halo Nucleus 22C At 235 MeV/nucleon

) of the very neutron-rich carbon isotope

Invariant Mass Spectroscopy of

^{22}

^{17}

C has been measured on a carbon target at 235 MeV/nucleon. A

C via One-neutron Knockout Reaction of

\sigma_R

^{18}

of

C

1.280 \pm 0.023