E2 moments andg-factors in neutron deficient lead isotopes

Abstract

The half-lives of the (vi13/2) 2 I'=12 + isomers in 19~were measured as T1/2 =7.9 (4) gs and 1.10(5)gs, respectively. The quadrupole moment and the g-factor of the corresponding state in 194pb were determined to Q=49(3) elm 2 and g=-0.167(2) using the perturbed angular distribution method. Additional g-factor and lifetime information was obtained for a number of isomers in 194'195'196'197'198'199' z~176 also involving i~3/2 neutrons. The results are discussed in comparison to a two-quasiparticle Tamm-Dancoff calculation in the full shell using the surface delta interaction.

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

“…3a, b), and the y-ray spectrum preceding the 48 keV transition shows the 14 + ~ 12 + 929 keV line and some higher lying transitions. The isomeric In= 12 + lifetime was measured to be T1/2 = 210 (5) ns and found to be in excellent agreement with the previous results 211 ns [2,7]. So far it had not been clear whether the In= 9-state decays directly to the Ex--2141 keV In= 7-level or through an intermediate state [13].…”

“…In the following discussion we will use these two alternative approaches to the structure of the lead isotopes. [15], whereas the 9-7-transition with the present lifetime fits well into the experimental and theoretical E2 systematics [2].…”

“…The L--M spacing strongly favours E2 for the 88 keV and M1 for the 70 keV transition. The 830 keV transition is pure dipole [-6] and the isomer above these transitions has the neutron configuration v(i13/~) 3, as deduced from its gfactor, and probably In= 33/2 + [2]. As also the measured lifetime and transition energy fit very well (see Chap.…”

“…So far it had not been clear whether the In= 9-state decays directly to the Ex--2141 keV In= 7-level or through an intermediate state [13]. Stenzel et al [2] have found that at least two half lives, namely T1/2 = 3.7 gs followed by T1/2 = 14 ns are involved. The total L-conversion strength of a 90 keV transition is 13% per transition for M1 and 65% for E2 multipolarity, which has to be compared with 74% for the 48 keV E2-transition.…”

“…This has been discussed in [1][2][3][4][5][6][7][8] and we will resume the discussion based on the more complete information that is now available. The spherical seniority shell model and the results of a quasiparticle Tamm-Dancoff approach will be used to discuss the experimental results.…”