An Experiment on the Anomalous Scattering ofμ-Mesons by Nucleons

Large angle scattering of fast $\mu$-mesons by an iron plate, 6 cm thick, has been investigated by means of a counter-hodoscope which recorded separately two energy bands: from 200 Mev to 320 Mev kinetic energy, and from 320 Mev to infinity. About half a million incident $\mu$-mesons were counted. Upper limits for the cross sections for anomalous scattering were obtained: about 4.5×${10}^{-29\mathrm{}}$ ${\mathrm{cm}}^2$/nucleon for the low energy band; about 2.3×${10}^{-30\mathrm{}}$ ${\mathrm{cm}}^2$/nucleon for the high energy band. Also an upper limit for the cross section for production of penetrating showers by $\mu$-mesons at sea level is given. We found a cross section of ${10}^{-30\mathrm{}}$ ${\mathrm{cm}}^2$/nucleon for showers of at least two particles of which at least one is emitted at an angle larger than 20° with a range of at least 7 cm Fe+5 cm Pb.