Spectral shapes and a beta-gamma directional correlation in the beta decay of 172Tm(JΠ = 2-)

Hansen, P. G. ; Nielsen, H. L. ; Wilsky, K. ; Agarwal, Y. K. ; Baba, C. V. K. ; Bhattacherjee, S. K. (1966) Spectral shapes and a beta-gamma directional correlation in the beta decay of 172Tm(JΠ = 2-) Nuclear Physics, 76 (2). pp. 257-267. ISSN 0029-5582

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Official URL: http://dx.doi.org//10.1016/0029-5582(66)90022-8

Related URL: http://dx.doi.org/10.1016/0029-5582(66)90022-8


The isotope 172Tm populates the 0+, 2+ and 4+ states of the 172Yb ground-state rotational band directly in beta decay. The shapes and intensities of the three beta groups have been measured by means of a six-gap magnetic spectrometer operated in coincidence with a NaI(Tl) crystal. The experimental shape factor plots are taken relative to the 90Y shape factor measured in the same circumstances, and it is concluded that on this basis the shapes of all three 172Tm beta groups agree with the theoretical shape for a first-forbidden unique transition. The directional correlation for the 2-(β)2+(γ)0+ cascade has been measured at six energies from 1010 to 1550 keV and these results too are consistent with the assumption that the 2- →2+ beta transition is purely of tensor rank 2. The data for the 2- →2+ transition are analysed on the basis of the modified Bij approximation, which defines parameters X and Y corresponding to the relative contributions of tensor ranks 0 and 1 respectively. The shape measurement provides the limit X2+Y2 ≦ 0.10, whereas the angular correlation measurement gives Y = 1.64X+(0.02±0.03). The reduced transition probabilities (ƒ1t)- can therefore be compared with the theoretical intensity rules for λ = 2, which predict the ratios 0.70 : 1 : 0.05 for the branches to the 0+, 2+ and 4+ states. The experimental result is (0.63±0.19) : 1 : (0.046±0.007).

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Radioactivity 172Tm [from n-capture in 170Er, Chem]; Measured Eβ , Iβ , ßy-coinc. Shape Factors, ßy-coinc(θ); Deduced log ƒ1t's, Multipolarity of β. Enriched Target
ID Code:3422
Deposited On:11 Oct 2010 09:16
Last Modified:18 May 2011 08:56

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