SOME NEW NEUTRON SEPARATION ENERGIES FOR ISOTOPES OF Hg, Tl, Pb, AND Bi

Abstract

Values derived from mass spectral doublets are reported for the following mass differences: Hg200−Hg198, Hg201−Hg199, Hg202−Hg200, Hg204−Hg202, Tl205−Tl203, Pb206−Pb204, Pb208−Pb206, Bi209−Pb207, Pb207−Tl205, Pb206−Hg204, and Tl203−Hg201. These mass differences are combined with existing reaction and disintegration data to yield single- and double-neutron separation energies for several of the isotopes of the above elements. The resulting neutron separation energy curves for even N are strikingly similar in shape and all exhibit an abrupt change in slope at N = 124. The curves for odd N do not display the same regularity. Currently accepted values for the total decay energies Tl204–Hg204 and Tl202–Hg202 are probably too large and too small, respectively, but current values for Pb205–Tl205 and Bi208–Pb208 are confirmed.