Lifetimes in Neutron-Rich Nd Isotopes Measured by a Doppler Profile Method

The Eurogam-1 array has been used to study γ rays emitted following the spontaneous fission of a ²⁴⁸Cm source. Yrast level schemes for the neutron-rich nuclei 152,154,156Nd have been constructed. The stopping of the Nd fragments in the source material leads to Doppler-broadened line shapes for those states that have lifetimes comparable to the stopping time. This paper describes the first measurements of lifetimes of medium-spin states in very neutron-rich nuclei obtained from the analysis of these line shapes. The transition quadrupole moments for the yrast states in the spin range (10-16) have been deduced to be 5.88 ±{} 0.08 e b (¹⁵²Nd), 5.75 ±{} 0.10 e b (¹⁵⁴Nd), and 5.33 ±{} 0.16 e b (¹⁵⁶Nd).