Coulomb excitation of radioactive (21)Na and its stable mirror (21)Ne

M. A. Schumaker*, D. Cline, G. Hackman, A. C. Morton, C. J. Pearson, C. E. Svensson, C. Y. Wu, A. Andreyev, R. A. E. Austin, G. C. Ball, D. Bandyopadhyay, J. A. Becker, A. J. Boston, H. C. Boston, L. Buchmann, R. Churchman, F. Cifarelli, R. J. Cooper, D. S. Cross, D. DashdorjG. A. Demand, M. R. Dimmock, T. E. Drake, P. Finlay, A. T. Gallant, P. E. Garrett, K. L. Green, A. N. Grint, G. F. Grinyer, L. J. Harkness, A. B. Hayes, R. Kanungo, K. G. Leach, G. Lee, R. Maharaj, J. -P. Martin, F. Moisan, S. Mythili, L. Nelson, O. Newman, P. J. Nolan, J. N. Orce, E. Padilla-Rodal, A. A. Phillips, M. Porter-Peden, J. J. Ressler, R. Roy, C. Ruiz, F. Sarazin, D. P. Scraggs, J. C. Waddington, J. M. Wan, A. Whitbeck, S. J. Williams, J. Wong

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The low-energy structures of the mirror nuclei (21)Ne and radioactive (21)Na have been examined by using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of similar to 5x10(6) ions/s were accelerated to 1.7 MeV/A and Coulomb excited in a 0.5 mg/cm(2) (nat)Ti target. Scattered beam and target particles were detected by the segmented Si detector BAMBINO, while gamma rays were observed by using two TIGRESS HPGe clover detectors perpendicular to the beam axis. For each isobar, Coulomb excitation from the 3/2(+-) ground state to the first excited 5/2(+-) state was observed and B(E2) values were determined by using the 2(+)-> 0(+) de-excitation in (48)Ti as a reference. The phi segmentation of BAMBINO was used to deduce tentative assignments for the signs of the mixing ratios between the E2 and M1 components of the transitions. The resulting B(E2)up arrow values are 131 +/- 9 e(2) fm(4) (25.4 +/- 1.7 W.u.) for (21)Ne and 205 +/- 14 e(2) fm(4) (39.7 +/- 2.7 W.u.) for (21)Na. The fit to the present data and the known lifetimes determined E2/M1 mixing ratios and B(M1)down arrow values of delta=(-)0.0767 +/- 0.0027 and 0.1274 +/- 0.0025 mu(2)(N) and delta=(+)0.0832 +/- 0.0028 and 0.1513 +/- 0.0017 mu(2)(N) for (21)Ne and (21)Na, respectively (with Krane and Steffen sign convention). By using the effective charges e(p)=1.5e and e(n)=0.5e, the B(E2) values produced by the p-sd shell model are 30.7 and 36.4 W.u. for (21)Ne and (21)Na, respectively. This analysis resolves a significant discrepancy between a previous experimental result for (21)Na and shell-model calculations.

Original languageEnglish
Article numberARTN 044321
Number of pages13
JournalPhysical Review C
Issue number4
Publication statusPublished - 23 Oct 2008



Cite this