Conversion electron measurement of isomeric primary transitions in196, 198, 199, 200, 201Pb

Abstract

The transition energies of nine low energy primary transitions from high spin isomers in 196, i98,199,zoo,zolpb have been measured with conversion electron spectroscopy using e-e-and e-7 coincidences. B(E2) values as deduced from the measured lifetimes and transition energies are discussed in terms of seniority shell model configurations and of a quasiparticle Tamm-Dancoff approach using the surface delta interaction. A revised discussion of the effective E2 charge in neutron deficient Pb isotopes is presented.

Yrast isomers in tin nuclei from heavy ion collisions and the νh11/2subshell filling

“…Using </zM/2k^|/?ii/2)=32 fm^ for the radial matrix element [14], one obtains eca(h\\/2) =0.88(4)^. This value is very close to that for the /13/2 neutron hole near ^^^Pb, e.g., ee(T(/i3/2) ="0.91 (4)^ from the analogous 12"*"-• 10"*" transition between 0*13/2)^ states in ^^^Pb [15]. In each case, this effective charge must be associated with high-energy 2"*" excitations of the closed core.…”

Study of isomeric states in 198,200,202,206Pb and 206Hg populated in fragmentation reactions

“…Isomeric decays of three previously reported states [41,44,47,50] -an I π = 19 − with T 1/2 = 72(3) ns, an I π = 12 + with T 1/2 = 199(3) ns, and an I π = 9 − with T 1/2 = 448(12) ns -have been analysed. The (9 − ) isomer was implicitly observed, due to the fact that it was fed from the states above (see Fig.…”

“…Therefore, the isomeric ratio of the (9) − state could not be evaluated. The half-life analysis regarding the (7) − state relied on the half-life value of the (9) − isomer extracted from a conversion electron measurement performed by Sun et al [50].…”

“…In fact, already in Refs. [49,50] the problem was noticed, and a solution suggested based on another 7 − state, supposedly decaying by a hitherto unobserved low-energy transition. Theoretically, such an additional level is likely to be present, though not yrare.…”

“…Isomeric decays of three previously reported states [45,48,50,53]-an I π =19 − with T 1/2 =72(3) ns, an I π =12 + with T 1/2 =199(3) ns, and an I π =9 − with T 1/2 =448(12) ns -have been analysed. The three relevant decay curves are shown in figure 7.…”