Entrance Channel Correlations in CALCIUM-40

Angular distributions and excitation functions of the ^{39}K(p, alpha_0) reaction were measured for 68 resonances in the proton energy range E_ {rm p} = 2.2 MeV to 4.0 MeV. This experiment was performed with an overall energy resolution of 350 eV to 400 eV (FWHM) at the Triangle Universities Nuclear Laboratory KN Van de Graaff accelerator. Angular correlation methods were used to derive expressions for the ^{39}K(p, alpha_0) angular distributions. For several of the 2^+ resonances, the experimental angular distributions yielded two possible solutions for the proton partial reduced widths. These solutions were then compared with the elastic scattering data to determine the correct solution. Three sets of reduced widths and one pair of reduced width amplitudes were obtained for 30 of the 2^+ resonances. For the 1^- resonances, the angular distributions and excitation functions did not provide sufficient information to uniquely determine the reduced widths, although detailed spectroscopic information was obtained for 13 resonances. Statistical analyses were performed on the 2 ^+ reduced widths and amplitudes. The proton partial widths agree well with Porter-Thomas distribution. There are strong width correlations between two of the three proton channels and between the gamma_ {20} and gamma_{22 } reduced width amplitudes. These data were transformed into the zero representation; again there is a strong width correlation. These channel correlations are interpreted as evidence for direct reactions. These data are the first results on entrance channel width and amplitude correlations.