Measurement of the dp -> He-3 eta reaction near threshold

Total and differential cross sections for the He 3 center-of-mass momenta in the range from 17.1 MeV/ c to 87.5 MeV/ c . The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target detecting the He 3 ejectiles with the COSY-11 facility. The forward–backward asymmetries of the differential cross sections deviate clearly from zero for center-of-mass momenta above 50 MeV/ c indicating the presence of higher partial waves in the final state. Below 50 MeV/ c center-of-mass momenta a fit of the final state enhancement factor to the data of the total cross sections results in the He 3 – η scattering length of |a|=4.3±0.5 fm | a | = 4.3 ± 0.5 fm .