Coulomb excitation of radioactive ^{20, 21}Na

The low-energy structures of the radioactive nuclei ^{20, 21}Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ~ 5×10⁶ ions/s were accelerated to 1. 7MeV/A and Coulomb excited in a 0. 5mg/cm^2natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for γ-ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For ²¹Na, Coulomb excitation from the 3/2⁺ ground state to the first excited 5/2⁺ state was observed, while for ²⁰Na, Coulomb excitation was observed from the 2⁺ ground state to the first excited 3⁺ and 4⁺ states. For both beams, B (λL) values were determined using the 2⁺ → ⁰ de-excitation in ⁴⁸Ti as a reference. The resulting B(E2) ↓ value for ²¹Na is 137±9 e²2fm⁴, while the resulting B(λL) ↓ values for ²⁰Na are 55±6 e²fm⁴ for the 3⁺ → 2⁺, 35.7±5. 7 e²fm⁴ for the 4⁺ → 2⁺, and 0. 154±0. 030 μN² for the 4⁺ → 3⁺ transitions. This analysis significantly improves the measurement of the ²¹Na B(E2) value, and provides the first experimental determination of B(λL) values for the proton dripline nucleus ²⁰Na.-1