Search for a 11/2??3/2+ M 4 transition in141Sm

Abstract

The electromagnetic decay of the 11/2-141,,Sm is investigated. Internal conversion electron and X-ray-conversion electron coincidence measurements indicate that the state undergoes fl+ and electron capture decay with 99.69% strength and the remaining 0.31% goes to a 174.2_+0.3 keV M4 transition. The K/L conversion electron intensity ratio for the transition is measured to be 1.7___0.4. The energy of the 11/2-is established at 175.8_+ 0.3 keV above the 1/2 + ground state in l~*Sm. Systematics of the M4 transitions in the N--79 and 81 isotones are discussed.

The141Eu nuclide and its decay properties

“…Figure 9 also displays the systematics of the first 1/2 +, 3/2 + and 11/2-states of these isotones. Because of the similarity between these states in this isotone series and those of the N = 81 isotone series, we suggested in our earlier works [7,8] [22]. In our previous study of the decay properties of the lighter mass odd-A, N =78 isotones [8], we noted that the decay energy between the first 5/2 + state in the N=78 isotones and the first 3/2 + state in the N=79 isotones increases linearly with the mass A.…”

“…9), the first 3/2 + state in a~lSm should lie very close to the 1/2 + ground state. We subsequently searched for a 11/2-43/2 + M4 transition and found it at 174.2 +_0.3 keV [7]. Since we did not observe any transition between the 3/2 + and the 1/2 + states, this may be taken as another indication of the closeness of the two states in energy.…”