A study has been made of the K-p interactions in a hydrogen bubble chamber. Cross sections have been determined at 25-MeV/c intervals in the range 75 to 275 MeV/c K~ lab momentum. About 90% of the hyperons were produced by K~-p interactions at rest, and these events were used to calculate at-rest production ratios and hyperon lifetimes.The observed hyperon decay rates from this experiment yield the following hyperon mean lifetimes: r s -= (1.58=fc0.06)X10 -10 sec, r S 4-=(0.765±0.04)X10-10 sec, and r A = (2.69±0.11)X10-10 sec. The observed branching ratios for S + and A decay are (2+ -> 7T + +^)/[(S+ -> TT + +W) + (S + -* 7r°+£)]=0.490=fc0.024,The K~-p interactions occurring at rest yield hyperon production rates in the ratio 2-:2+:2 0 :A=0.447:0.208:0.281:0.064.The in-flight K~-p interactions are dominated by the hyperon production process. Analysis of the elastic-scattering angular distribution shows that the nuclear part of the amplitude has a large imaginary part and a real part consistent with zero. The absorption cross section is nearly geometric for s-wave interactions throughout the observed laboratory momentum range. Angular distributions for all the K~-p interactions are quite consistent with isotropy. An s-wave zero-effective-range analysis of the K~-p interactions has been carried out. Two sets of parameters were found that give acceptable fits to all the data. The x 2 test gives probability of 48% for solution 1, and 8% for solution 2. The scattering lengths which best fit the data of this experiment are A Q = -0.220 +2.742*' for the isotopic spin-0 channel, and ,41 = 0.019+0.384* for the isotopic spin-1 channel. A schematic diagram of the beam is shown in Fig. 1.

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