Elsevier

Nuclear Physics A

Volume 170, Issue 3, 2 August 1971, Pages 467-484
Nuclear Physics A

The reaction 23Na(α, γ)27Al: (II). Spins, parities and mean lives of 27Al levels

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Abstract

Angular distribution and Doppler-shift attenuation measurements in the reaction 23Na(α,γ)27Al lead to the spin and parity assignments Jπ = 72+ to the 27AlEx = 4.58 MeV level, Jπ = 92+ to the levels at Ex = 5.43, 5.67 and 7.17 MeV, Jπ = 112+ to the 6.51 MeV level and Jπ = 92(+) to the 7.81 MeV level. The Eα = 2.69, 2.79 and 2.81 MeV resonance levels have Jπ = 112(+), 92 and 112+, respectively. Several quadrupole/dipole amplitude mixing ratios and γ-ray transition strengths are also reported. The combined evidence of the decay of the resonance levels and bound states leads to lower limits of 72, 32, 52, 52 and 72 for the spins of the 5.50, 5.96, 6.95, 7.44 and 7.66 MeV levels, respectively, and to similar spin limitations for seventeen resonances.

Mean lives of the 3.00, 4.51, 4.58, 5.43, 5.67, 5.96, 6.51, 7.66 and 7.81 MeV levels are τm = 88 ± 10, 315 ± 40, 19 ± 6, 32 ± 6, 16 ± 4, 24 ± 18, 17 ± 6, 19 ± 6 and 26 ± 6 fs, respectively. Upper limits are given for the mean lives of fourteen other bound states. Eight of these follow from additional 26Mg(p,γ)27Al Doppler-shift attenuation measurements.

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