Alpha-decay study of 218U; a search for the sub-shell closure at Z = 92

Leppänen, A. -P; Uusitalo, J; Eeckhaudt, S; Enqvist, T; Eskola, K; Grahn, T; Heßberger, F. P; Greenlees, P. T; Jones, P; Julin, R; Juutinen, S; Kettunen, H; Kuusiniemi, P; Leino, M; Nieminen, P; Pakarinen, J; Perkowski, J; Rahkila, P; Scholey, C; Sletten, G

Alpha-decay study of 218U; a search for the sub-shell closure at Z = 92

Date

2005-09

Authors

Leppänen, A. -P

Uusitalo, J

Eeckhaudt, S

Enqvist, T

Eskola, K

Grahn, T

Heßberger, F. P

Greenlees, P. T

Jones, P

Julin, R

Publisher

EDP Sciences

Abstract

Neutron-deficient uranium isotopes were studied via α spectroscopic methods. A low-lying α-decaying isomeric state was found in ²¹⁸U. The new isomeric state was assigned spin and parity Iπ=8⁺. The isomer decays by α emission with an energy E = 10678(17)keV and with a half-life T1/2 = (0.56⁺⁰·²⁶-₀.₁₄)ms. The known alpha-decay properties of the ground state of ²¹⁸U was measured with improved statistics. The ground-state α-decay has an energy E = 8612(9)keV and a half-life T1/2 = (0.51⁺⁰·¹⁷ˍ₀.₁₀)ms.