EXCITATION-ENERGY OF THE PI-S(1 2) INTRUDER STATE IN BI-189/

In a series of Ti-48 bombardments of Sm-144 the decay energy of the Bi -189(m) (pi s(1/2)) alpha transition that proceeds to the (pi s(1/2)) ground state of Tl-185 was measured to be 7.30(4) MeV. This result est ablishes the excitation energy of Bi-189(m) as 190(40) keV rather than the adopted 92(10)-keV value. Our data indicate a leveling off in exc itation energy at N approximate to 106 for the s(1/2) intruder state i n the odd-A Bi isotopes rather than a continued drop at that neutron n umber as inferred by Coenen et al. in their discussion of intruder sta te systematics in the Pb region. Consequences of this discrepancy for the adopted excitation energy of the pi s(1/2) isomer in Bi-187 are di scussed.