Lifetime measurements of first excited states in ^{16,18}C (original) (raw)

The electric quadrupole transition from the first 2 + state to the ground 0 + state in 18 C was studied through lifetime measurement by an upgraded recoil shadow method applied to inelastically scattered radioactive 18 C nuclei. The measured mean lifetime is 18.9 ± 0.9 (stat) ± 4.4 (syst) ps, corresponding to a B(E2; 2 + 1 → 0 + gs ) value of 4.3±0.2±1.0 e 2 fm 4 , or about 1.5 Weisskopf units. The mean lifetime of the first 2 + state in 16 C was remeasured to be 18.0 ± 1.6 ± 4.7 ps, about four times shorter than the value reported previously. The discrepancy between the two results was resolved by incorporating the γ-ray angular distribution measured in this work into the previous measurement.