High-resolution measurement of absolute α-decay widths in O16

By using a large-acceptance position-sensitive silicon detector array in coincidence with the high-resolution Munich Q3D spectrograph, unambiguous measurements have been made of the absolute α-particle decay widths from excited states in O16* in the energy range 13.85 to 15.87 MeV. Carbon targets have been bombarded with 42-MeV Li6 beams to induce ₆¹²C(₃⁶Li, d)₈¹⁶O* reactions. The deuteron ejectiles were measured in the Q3D and the results gated by He4+C12 breakup products detected in the silicon array, the efficiency of which was modeled using Monte Carlo simulations. By comparing total population and breakup-gated spectra, the following absolute α-decay widths have been measured with high resolution: Γ_α0/Γ_tot =0.87±0.11 (13.980 MeV), 1.04±0.15 (14.302 MeV), 0.92±0.10 (14.399 MeV), 0.59±0.04 (14.815 MeV), 0.88±0.18 (15.785 MeV), and Γ_α1/Γ_tot=1.14±0.08 (14.660 MeV), 0.46±0.06 (14.815 MeV).