Energy Levels ofLi6from the Deuteron-Helium Differential Cross Sections

Abstract

The deuteron-helium differential cross sections presented in the preceding paper have been analyzed in terms of a dispersion formalism to classify energy levels of ${\mathrm{Li}}^6$. A level at $E_x=2.185\mathrm{}$ Mev is confirmed to be a single particle, $3^{+}$, $T=0\mathrm{}$ level. The broad anomaly extending from 3 Mev to the limit of observation, 4.62 Mev, cannot be analyzed in terms of a single level. Instead, it has been fitted with two single-particle levels, a $2^{+}$ level at $E_x=4.53\mathrm{}$ Mev in ${\mathrm{Li}}^6$ and a $1^{+}$ level at 5.4±0.5 Mev. The $1^{+}$ level cannot be located more accurately because only the tail is visible at the bombarding energies available. All of the other two-level combinations have been ruled out. The assignments, ($3^{+}$, $2^{+}$, $1^{+}$), and locations of the levels agree with an intermediate coupling model which is close to the $L-S$ extreme. In the neighborhood of and above the $3^{+}$ resonance the usual hard-sphere phase shifts, which are always negative, cannot be used for the $P$-wave. This result may indicate odd-parity states above the presently investigated energy region. For the other partial waves, hard-sphere phase shifts corresponding to radii anywhere from 3 to 5×${10}^{-13\mathrm{}}$ cm were satisfactory, provided the reduced width of the ground state of ${\mathrm{Li}}^6$ was simultaneously varied from the Wigner limit to very small values.