Slow Neutron Velocity Spectrometer Studies. V. Re, Ta, Ru, Cr, Ga

Abstract

New developments in the analysis of data near resonance levels are described. These allow more accurate values of the level constants to be determined from the measured areas above transmission curves and are more general in their applications. The effect of Doppler broadening is also taken into consideration. Transmission data on Re, Ta, Ru, Cr, and Ga are presented. The thermal region of Re is well matched by the relation $\ensuremath{\sigma}=5.0+15.8{E}^{\ensuremath{-}\frac{1}{2}}$. Resonances are found in Re at 2.18, 4.40, 5.92, 7.18, 11.3, 13.1, 17.7, and 21.1 ev. The strong level at 2.18 ev has been studied by the technique of using two samples of different thickness, giving ${\ensuremath{\sigma}}_{0}=5700$ barns and $\ensuremath{\Gamma}=0.090$ ev. The method of curve fitting was also applied to the transmission dip of the thick sample at 2.18 ev and confirms the values of ${\ensuremath{\sigma}}_{0}$ and $\ensuremath{\Gamma}$ from the area method. Curve fitting was also used on the 4.40-ev level. New data for Ta in the region above 5 ev are presented. Some transmission dips thought previously to be due to one level have now been resolved into two levels. There are levels at 6.11, 10.2, 13.7, 20.0, 24.0, 35.1, and 38.2 ev. The thermal region of Ru is well matched by the relation $\ensuremath{\sigma}=6.4\ifmmode\pm\else\textpm\fi{}0.39{E}^{\ensuremath{-}\frac{1}{2}}$. Resonance levels are observed at 9.8, 15.2, 24.1, and 40.9 ev. The thermal region of Cr is well matched by the relation $\ensuremath{\sigma}=3.8+0.7{E}^{\ensuremath{-}\frac{1}{2}}$. A resonance level is observed at 3800 ev. The nuclear cross section of Ga is given by $\ensuremath{\sigma}=7.3+0.35{E}^{\ensuremath{-}\frac{1}{2}}$ below 5 ev. In addition interference effects occur in the thermal region. Levels were found at 102 ev and 310 ev, with indications of levels at higher energies.