Coulomb excitation structure studies of 21Ne, 20?21Na
The low-energy structures of the radioactive nuclei 20,21Na, and the stable nucleus 21Ne have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ~5*10 6 ions/s were accelerated to 1.7 MeV/A and Coulomb excited in a 0.5 mg/cm2 'nat'Ti target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for [gamma]-ray detection, while scattered nuclei were observed by the Si detector B AMBINO. For 21Ne and 21Na, Coulomb excitation from the 3/2+ ground states to the first excited 5/2 + states were observed, while for 20Na, Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For all beams, 'B'(' [lambda]'L) values were determined using the 2+ [right arrow] 0+ de-excitation in 48Ti as a reference. The resulting 'B'('E'2) value for 21Ne is 87.5±5.8 e2fm4, for 21Na 'B'('E'2) =137±9 e 2fm4, while the resulting 'B'(' [lambda]'L) values for 20Na are 55±6 e 2fm4 for the 3+ [right arrow] 2+, 35.7±5.7 e2fm4 for the 4+ [right arrow] 2+, and 0.154±0.030 'N' 2 for the 4'+' [right arrow] 3+ transitions. This analysis significantly improves the measurement of the 21Na ' B'('E'2; 5/2+ [right arrow] 3/2+) value, improves the precision of this same transition in 21Ne, and provides the first experimental determination of 'B'(' [lambda]'L) values for the proton-dripline nucleus 20Na.