Experimental study on the 3p size-resonance in thep- wave neutron strength function

Using a silicon filtered fission neutron beam of an energy width of 20 keV around 143 keV we measured the total cross sections for 37 nuclides and elements having mass numbers between 87 and 140 and determined thep-wave strength functions. The 3P-resonance atA=98 shows no splitting into theP _3/2?P _1/2 doublet. The narrow resonance peak and the following broad distribution of thep-strength function (A=103 to 140) can approximately be reproduced by deformed optical model calculations. The spin-orbit term in the optical potential is consistent with the spin orbit force in the shell model. For nuclei around the closed (N=50) neutron shell a shell effect in thep-wave strength function is indicated.