Study of the $\beta$-decay of $^{11}$Li at ISAC/TRIUMF

The $\beta$-decay of $^{11}$Li was investigated at ISAC/TRIUMF with the 8$\pi$ spectrometer, an array of 20 Compton-suppressed HPGe detectors. Doppler-broadened line shapes appear in the $\beta$-decay spectrum, arising from the decay of excited states of $^{10}$Be populated by $\beta$- delayed one-neutron emission. A Monte Carlo simulation for these line shapes was developed, permitting the analysis of excited states in $^{10}$Be and neutron emitting states in $^{11}$Be . This experiment improves on a previous work [F. Sarazin et al., Phys. Rev. C 70 (2004) 031302R] through greater $^{11}$Li yield and the addition of Sceptar, a plastic scintillating array in the inner volume of the 8$\pi$. Analysis of the higher quality line shapes from the new experiment should help resolve discrepancies observed between the previous work and [Y. Hirayama et al., Phys.Lett. B 611 (2005) 239] (an experiment using polarized $^{11}$Li and time-of-flight neutron detectors) and possibly lead to new insights in the $\beta$-decay of $^{11}$Li. This work is partially supported by the US Department of Energy through Grant/ Contract No. DE-FG03-93ER40789.