§4.6.1 E_x=6.742 MeV

The 6.742 MeV state (E_res=330 keV) is thought to have J^π=1/2^- or 3/2^- due to the l=1 character of its ²⁰Ne(³He,α) angular distribution [Garret, Middleton et al. 1970]. A comparison of fits to the α-decay of this state using these assignments is shown in Figure 26. The J^π=3/2^- fit clearly does the better job, having a χ²/ν statistic of 1.96 versus 13.3 for the J^π=3/2^- fit.

Besids the total area, the only free parameter is p_1/2, with a best fit value of ${0.58}_{-0.12}^{+0.22}$ (see Figure 21a. Since this lies outside the allowable range of 0-0.5, and a new confidence region is found (see Figure 21b). The final result fit was ${\Gamma }_{\alpha }/\Gamma ={0.888}_{-0.030}^{+0.091}$ with p_1/2>0.44 at a 68.27% confidence level.

Figure 21: The E_x=6.742 MeV confidence regions for the fit parameters. Circles mark the best-fit coordinates. The inner and outer contours are the boundaries for the 68.27% and 90% confidence levels, respectively. (a) The left panel shows the initial fit, which resulted in a non-physical value for p_1/2. The physically allowed values are below and to the left of the lines. (b) The right panel shows the confidence regions obtained by not allowing p_1/2>0.5.

UNDER CONSTRUCTION