Gamma — Gamma Directional Correlation Measurements in 124 Te

Abstract

The levels of 124Te have recently been reinvestigated by Auer et al.1 ) and Meyer et al.2 ) from the decay of 124 Sb and by Ragaini et al.3 ) from the decay of 124I. The low excited states of 124Te exhibit a ‘vibrational’ pattern which could be expected for this nucleus (proton number 52 and neutron number differing by only 10 from the closed neutron shell). The measurements of Warner and Draper4) show, however, that the 4+ level at 1249 keV could also be considered as a member of the ground state quasi — rotational band. The 723 keV transition proceeds between the first and the second excited 2+ levels which would correspond to one and two phonon excitation respectively in the vibrational picture. The results of the measurements of the mixing ratio, δ723, for this transition are conflicting. From our previous measurements6) of β-γ directional correlation in the decay of 124 Sb we were able to calculate the mixing ratio of the 723 keV gamma transition. This measurement gave — 2.8 ≤δ723 ≤ −1.0. The β-γ directional correlation measurement by Paul7) was not precise enough to distinguish between δ723 — values in the region −5.0 ≤δ723 ≤ −0.7. There is a mistake in the interpretation of the 1368γ — (723γ) — 603γ directional correlation result obtained by Lindquist and Marklund8). Their experimental value, A22 = −0.027 ± 0.008, measured for this cascade gives 0.45 ≤ ∣δ723 ∣ ≤ 0.70 and not ∣δ∣ ≈ 1, as stated in their paper. The above mentioned results are less precise than the value δ723 = −4.1 ± 0.6 obtained by Glaubman and Oberholtzer9) from the β-γ-γ directional correlation measurement. The γ-γ measurements by Dorikens-Vanpraet et al.10) performed with scintillation detectors involve large corrections due to unresolved cascades. They favour δ723 ≈ −2,4.