Determination of the g-factor for several short-lived nuclear states

Abstract

The g-factors of nine excited nuclear states have been measured by observing the rotation of the angular correlation of a γ-γ cascade in a magnetic field whose direction was alternately switched up and down with respect to the plane of the measurement. The results are: 280-kev state of As^(75) (τ = 4 x 10^(-10) sec) g = (0.39 ± 0.12); 9l-kev state of pm^(147) (τ = 3.4 x 10^(-9) sec) g = (0.93 ± 0.20)/ G_2 where G_2 is between 0.5 and 1.0 ; 118-kev state of Tm^(169) (τ = 9.0 x 10^(-11) sec) g = (0.21 ± 0.07) ; 114-kev state of Lu^(175) (τ = 9.4 x 10^(-11) sec) g = (0.65 ± 0.25); 113-kev state of Hf^(177) (τ = 7 x 10^(-10) sec) g = (0.20 ± 0.06) ; l22-kev state of Sm^(152) (τ = 2.0 x 10^(-9) sec) g = (0.28 ± 0.07); 123-kev state of Gd^(154) (τ = 1.7 x 10^(-9) sec) g = (0.4 ± 0.5); 87-kev state of Dy^(160) (τ = 2.6 x 10^(- 9) sec) g = (0.28 ± 0.08) ; 8l-kev state of Er^(166) (τ = 2.4x 10 ^(-9) sec) g = (0.31 ± 0.06). The measurements have been compared to theoretical predictions. On the basis of the shell model, the probable value of the spin for the 9l-kev level of Pm^(147) is 5/2+. The results for Tm^(169), Lu^(175), and Hf^(177) have been interpreted using the Nilsson model. The results found are in qualitative agreement with theory, but some deviations, especially in Hf^(177), are noted. The measurements for the 2+ states 0f Sm^(152), Dy^(160), and Er^(166) provide a direct eva1uation of the rotational g-factor, g_R, of the collective model. The values found are about 3/4 of the value g_R = Z/A predicted for uniform nuclear flow. The effects of electronic paramagnetism in rare earths on these measurements are treated in an appendix. The assumptions necessary to interpret the observed rotation in terms of the g-factor are discussed.