g factors of the 9^- and 12⁺ isomeric states in ²⁰⁰Pb

Abstract

The g factors of the 9^- state (2.236 MeV, t=694 nsec) and the 12⁺ state (~3.1 MeV, t=228 nsec) in ²⁰⁰Pb have been measured as g(9^-)=-0.030(3) and g(12⁺)=-0.157(6) by a time-differential perturbed-angular-distribution technique. The states were populated by ¹⁹⁷Au(⁷Li, 4n)²⁰⁰Pb(9^-) and ¹⁹⁷Au(⁷Li, 3n)²⁰⁰Pb(12⁺) reactions with pulsed lithium beams. An in-beam superconducting magnet supplied a field of ~60 kG. The 9^- state g factor is in agreement with the additivity value obtained from empirical single-particle g factors for a (i_13/2^-1, f_5/2^-1)9^- configuration and consistent with a small anomalous orbital contribution δg_l for the neutron. The g factor for the 12⁺ state in ²⁰⁰Pb is in surprisingly good agreement with those for the (i_13/2)^-212⁺ state in ²⁰⁶Pb and the i_13/2^-1 state in ²⁰⁵Pb, in view of the possible existence of number-dependent effects.