Structure of Pt nuclei: (II). Structure of 192Pt investigated by electron-gamma and gamma-gamma directional correlations

Abstract

Electron-gamma and gamma-gamma directional correlation experiments are performed for various cascades in 192Pt by means of a sector-type double focussing beta-ray spectro-gonio- meter. The ratio of the EO and E2 nuclear matrix element between the second 2 + 2 and first 2 + 1 states is determined to be −(6±8) × 10 −3. The penetration factors of the M 1 internal conversion are obtained as follows: 0 ≦ λ ≦ 80 for the 296 keV (2 + 1 → 2 + 1); λ. ≈ −10 for the 308 keV (3 +→ 2 + 1); −35 ≦ λ ≦ 5 for the 605 keV (3 + → 2 + 1) transitions. The M1/E2 mixing ratios in the 296, 308 and 605 keV transitions are determined as −0.18±0.04, −0.09±0.09 and 0.30± 0.05, respectively. The new 1091 keV state is established from gamma-ray measurements with a Ge(Li) detector and the log ft values of beta transitions are derived from the intensity valence of the gamma-rays. The spin and parity are confirmed to be 3 − for the 1380 keV state. A new level scheme of 192Pt is presented and the level structure of the lower excited states are discussed from the view point of collective vibrational models.