Isomeric States in Light Even Pb Isotopes

Searches for isomers in the μsec range for isotopes

{}^{194 - 200}{Pb}

revealed a new lifetime of

T_{\frac{1}{2}} = 10

μsec for the 1541-keV state in

{}^{194}{Pb}

and confirmed the

T_{\frac{1}{2}} = 0.5

-μsec and

T_{\frac{1}{2}} = 4

-μsec half-lives for the

9^{-}

states in

{}^{200}{Pb}

and

{}^{198}{Pb}

, respectively. No lifetime in the μsec range was found in

{}^{196}{Pb}

indicating that the 688.9-keV transition is not of

E 3

character as proposed before by Chojnacki et al. Lifetimes of

T_{\frac{1}{2}} = 134 \pm 20

nsec and

T_{\frac{1}{2}} = 61 \pm 14

nsec for the

5^{-}

and

9^{-}

states in

{}^{196}{Pb}

were derived from a

γ - γ - t

coincidence experiment. A possible distortion of the time spectra obtained in in-beam experiments is discussed. Experimental

B (E 2)

and

B (E 3)

values are compared with single-particle estimates for some possible two-neutron configurations of the states involved.

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