Observation of an enhanced $4_1^{+}$ → $0^{+}$ crossover transition in ${}_{}{}^{202}{}_{}{}^{}\mathrm{Pb}$ by conversion electron spectroscopy

An enhanced $E4\mathrm{}$ crossover transition ($4_1^{+}$ → $0^{+}$) in ${}_{}{}^{202}{}_{}{}^{}\mathrm{Pb}$ has been observed by means of conversion electron spectroscopy using a Si(Li) detector with a special filter of permanent magnets. This method has shown to be much more sensitive in this case than the measurement of the $E4\mathrm{}$ $\gamma$ rays. The branching ratio $\frac{E4(4_1^{+}\to 0^{+})}{E2(4_1^{+}\to 2_1^{+})}$ was found to be (3.8 ± 0.6)${10}^{-6\mathrm{}}$ resulting in a partial half-life of (4.6 ± 0.8) Weisskopf units for the $E4\mathrm{}$ transition.

RADIOACTIVITY ${}_{}{}^{202}{}_{}{}^{}\mathrm{Pb}\left[{}_{}{}^{203}{}_{}{}^{}\mathrm{Tl}\right(d, 3n\left)\right]$; measured $E_{\gamma }$, $J_{\gamma }$, $E_e$, $J_e$; deduced $E4\mathrm{}$-transition probability for the 1383 keV ($4_1^{+}$ → $0^{+}$) transition.