Narrowing of the neutron sd–pf shell gap in 29Na

• Published in: Physics letters. B 2009-04, Vol.674 (3), p.168-171
• Main Authors: Hurst, A.M., Wu, C.Y., Becker, J.A., Stoyer, M.A., Pearson, C.J., Hackman, G., Schumaker, M.A., Svensson, C.E., Austin, R.A.E., Ball, G.C., Bandyopadhyay, D., Barton, C.J., Boston, A.J., Boston, H.C., Churchman, R., Cline, D., Colosimo, S.J., Cross, D.S., Demand, G., Djongolov, M., Drake, T.E., Garrett, P.E., Gray-Jones, C., Green, K.L., Grint, A.N., Hayes, A.B., Leach, K.G., Kulp, W.D., Lee, G., Lloyd, S., Maharaj, R., Martin, J.-P., Millar, B.A., Mythili, S., Nelson, L., Nolan, P.J., Oxley, D.C., Padilla-Rodal, E., Phillips, A.A., Porter-Peden, M., Rigby, S.V., Sarazin, F., Sumithrarachchi, C.S., Triambak, S., Walker, P.M., Williams, S.J., Wong, J., Wood, J.L.
• Format: Article
• Language: English
• Subjects: Coulomb excitation; Exact sciences and technology; Island of inversion; ISOL; Nuclear physics; Physics; Reduced transition matrix element; The physics of elementary particles and fields
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2009.03.017

The wave-function composition for the low-lying states in 29Na was explored by measuring their electromagnetic properties using the Coulomb-excitation technique. A beam of 29Na ions, postaccelerated to 70 MeV, bombarded a 110Pd target with a rate of up to 600 particles per second at the recently commissioned ISAC-II facility at TRIUMF. Six segmented HPGe clover detectors of the TIGRESS γ-ray spectrometer were used to detect deexcitation γ rays in coincidence with scattered or recoiling charged particles in the segmented silicon detector, BAMBINO. The reduced transition matrix element |〈521+||E2||32gs+〉| in 29Na was derived to be 0.237(21) e b from the measured γ-ray yields for both projectile and target. This first-time measured value is consistent with the most recent Monte Carlo shell-model calculation, indicating a significant admixture of both sd and pf components in the wave function, and also providing evidence for the narrowing of the neutron sd–pf shell gap from ∼6 MeV for stable nuclei to ∼3 MeV for 29Na.