New Element Mendelevium, Atomic Number 101

Abstract

the 1.75-Mev level arises from the excitation of two protons to a (got&)' configiration, one may expect some additional forbiddenness.In such a transition, the 39th proton of Y" must change from a p~t2 to a gsts state, in addition to the ordinary single particle transformation of a de~n eutron into a g9~2 proton.For this reason, a reduced intensity for the transition to the 1.75-Mev level may be expected.Very precise measurements on the beta spectrum of Y" gave no indication of any other group of beta rays between 0.5 Mev and the end point at 2.26 Mev.This fact, combined with the absence of any gamma radia- tion (other than bremsstrahlung) suggests that the 1.75-Mev level is the 6rst excited state of the even-even nucleus Zr".I' This work was