The production of beauty particles in π--U interactions at 320 GeV energy

B overlineB production in π^--uranium interactions has been observed at 320 GeV beam energy looking at events with three muons in the final state. The cross section is found to be σ _{B overlineB} = 4.5±1.4±1.4 nb per nucleon (for a linear A-dependence) or σ _{B overlineB} = 17.6±5.5±5.5 nb per nucleon (assuming A^0.75 dependence). An estimate of x_F distribution is given.