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

The wave-function composition for the low-lying states in Na-29 was explored by measuring their electromagnetic properties using the Coulomb-excitation technique. A beam of Na-29 ions, postaccelerated to 70 MeV, bombarded a Pd-110 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 gamma-ray spectrometer were used to detect deexcitation gamma rays in coincidence with scattered or recoiling charged particles in the segmented silicon detector, BAMBINO. The reduced transition matrix element vertical bar vertical bar in Na-29 was derived to be 0.237(21) e b from the measured gamma-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 similar to 6 MeV for stable nuclei to similar to 3 MeV for Na-29. (C) 2009 Elsevier B.V. All rights reserved

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

The wave-function composition for the low-lying states in Na-29 was explored by measuring their electromagnetic properties using the Coulomb-excitation technique. A beam of Na-29 ions, postaccelerated to 70 MeV, bombarded a Pd-110 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 gamma-ray spectrometer were used to detect deexcitation gamma rays in coincidence with scattered or recoiling charged particles in the segmented silicon detector, BAMBINO. The reduced transition matrix element vertical bar vertical bar in Na-29 was derived to be 0.237(21) e b from the measured gamma-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 similar to 6 MeV for stable nuclei to similar to 3 MeV for Na-29. (C) 2009 Elsevier B.V. All rights reserved

First results with TIGRESS and accelerated radioactive ion beams from ISAC: Coulomb excitation of20,21,29Na

The TRIUMF‐ISAC Gamma‐Ray Escape Suppressed Spectrometer (TIGRESS) is a state‐of‐the‐art γ‐ray spectrometer being constructed at the ISAC‐II radioactive ion beam facility at TRIUMF. TIGRESS will be comprised of twelve 32‐fold segmented high‐purity germanium (HPGe) clover‐type γ‐ray detectors, with BGO∕CsI(Tl) Compton‐suppression shields, and is currently operational at ISAC‐II in an early‐implementation configuration of six detectors. Results have been obtained for the first experiments performed using TIGRESS, which examined the A  =  20, 21, and 29 isotopes of Na by Coulomb excitation