Coulomb Excitation of States inPt195

Abstract

Gamma rays of 99, 110, 130, 140, 210, and 240 kev have been observed from Coulomb excitation of ${\mathrm{Pt}}^{195}$ (platinum target containing 60.1% ${\mathrm{Pt}}^{195}$) with 3.0- to 5.5-Mev protons and $\ensuremath{\alpha}$ particles. The energy dependence of the gamma-ray yields indicates direct excitation of states at 99, 130, 210, and 240 kev. The 140-kev gamma ray is a cascade transition between states at 240 and 99 kev. These results do not agree with the conclusions of Bernstein and Lewis who measured the Coulomb excitation functions of the internal conversion electrons and found evidence for direct excitation of levels at 31 and 130 kev but no evidence for direct excitation of a level at 99 kev. The angular distributions of the 240- and 210-kev gamma rays and the 140-kev gamma ray in coincidence with $K$ x-rays from internal conversion of the 99-kev transition have been measured with respect to the incident ion beam on a thick target. These measured distributions are consistent with an assignment of $\frac{5}{2}(E2)\frac{1}{2}$, $\frac{3}{2}(E2+M1)\frac{1}{2}$ with ${(\frac{E2}{M1})}^{\frac{1}{2}}=0.37\ifmmode\pm\else\textpm\fi{}0.02$, and $\frac{5}{2}(E2+M1)\frac{3}{2}$ with ${(\frac{E2}{M1})}^{\frac{1}{2}}=\ensuremath{-}(0.13\ifmmode\pm\else\textpm\fi{}0.03)$ for the 240-, 210-, and 140-kev transitions, respectively. The $B(E2)$ and $B(M1)$ for decay of these states have been determined.