LIFETIMES OF LEVELS IN A=10 NUCLEI

The Doppler-shift attenuation method was used to obtain the following mean lifetimes (in psec) for the indicated nuclear levels: C10(3.36), τ=0.155±0.025; B10(3.59), τ=0.150±0.015; Be10(3.37), τ=0.189±0.020; B10(2.15), τ=2.7-0.4+0.5. A limit of τ<30 fsec is obtained for B10(1.74), which is a factor of 8 greater than, and therefore consistent with, the lifetime computed from the analog β decay of C10. Transition strengths obtained from the B10(2.15) and B10(3.59) lifetimes are in good agreement with the effective-interaction calculations of Cohen and Kurath, as modified by Warburton et al. The C10(3.36) and Be10(3.37) states decay by analog E2 transitions: 2+, T=1→0+, T=1, with Tz=±1, whose strengths are well described by calculations of Kurath's for an effective charge εn=εp=0.5. An upper limit was obtained for the corresponding transition 5.17 → 1.74 in B10(Tz=0) which is consistent (factor of 4 greater) with the analog strengths observed in the Tz=±1 nuclei. © 1968 The American Physical Society.