Coulomb excitation of radioactive {sup 21}Na and its stable mirror {sup 21}Ne

Journal Article · Wed Oct 15 00:00:00 EDT 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.78.044321· OSTI ID:21192300

Schumaker, M A; Svensson, C E; Demand, G A; Finlay, P; Garrett, P E; Green, K L; Grinyer, G F; Leach, K G; Phillips, A A; Wong, J ^[1]; Cline, D; Hayes, A B; Whitbeck, A ^[2]; Hackman, G; Morton, A C; Pearson, C J; Andreyev, A; Ball, G C; Buchmann, L; Churchman, R ^[3]

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1. Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1 (Canada)
2. Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States)
3. TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada)

The low-energy structures of the mirror nuclei {sup 21}Ne and radioactive {sup 21}Na have been examined by using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of {approx}5x10{sup 6} ions/s were accelerated to 1.7 MeV/A and Coulomb excited in a 0.5 mg/cm{sup 2} {sup 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){sup +} ground state to the first excited (5/2){sup +} state was observed and B(E2) values were determined by using the 2{sup +}{yields}0{sup +} de-excitation in {sup 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{sup 2} fm{sup 4} (25.4{+-}1.7 W.u.) for {sup 21}Ne and 205{+-}14 e{sup 2} fm{sup 4} (39.7{+-}2.7 W.u.) for {sup 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}{sub N}{sup 2} and {delta}=(+)0.0832{+-}0.0028 and 0.1513{+-}0.0017 {mu}{sub N}{sup 2} for {sup 21}Ne and {sup 21}Na, respectively (with Krane and Steffen sign convention). By using the effective charges e{sub p}=1.5e and e{sub n}=0.5e, the B(E2) values produced by the p-sd shell model are 30.7 and 36.4 W.u. for {sup 21}Ne and {sup 21}Na, respectively. This analysis resolves a significant discrepancy between a previous experimental result for {sup 21}Na and shell-model calculations.

• OSTI ID: 21192300
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 78, Issue 4; Other Information: DOI: 10.1103/PhysRevC.78.044321; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COULOMB EXCITATION
DE-EXCITATION
E2-TRANSITIONS
EFFECTIVE CHARGE
GAMMA DETECTION
GAMMA RADIATION
GROUND STATES
LI-DRIFTED SI DETECTORS
LIFETIME
M1-TRANSITIONS
MEV RANGE 01-10
MIRROR NUCLEI
MIXING RATIO
NEON 21
RADIOACTIVE ION BEAMS
RADIOISOTOPES
SCATTERING
SHELL MODELS
SODIUM 21
TITANIUM 48