K+Meson Photoproduction from Complex Nuclei

$K^{+}$ meson yields have been measured from various elements using a bremsstrahlung beam of maximum energy of 1150 MeV. The $K^{+}$ mesons were detected using a magnetic spectrometer set at a momentum of 415 $\frac{\mathrm{MeV}}{c}$ and laboratory angle of 35°. These kinematical conditions correspond to an angle of 90° in the center of mass and a photon energy of 1054 MeV for the reaction $\gamma +p\to K^{+}+\Lambda$. The targets used were Be, C, Al, Cu, Ag, W, and Pb. The results show a slight decrease in the yield per proton as a function of atomic number. A crude estimate yields a mean free path in nuclear matter of the order of 10 F for the geometry of this experiment.