  Antimatter search results of the Alpha Magnetic Spectrometer (AMS) detector
are presented. About 100 million triggers were collected in the 1998 precursor
flight onboard space shuttle Discovery. This ten day mission exposed the
detector on a 51.7 degrees orbit at an altitude around 350 km. Identification
of charged cosmic rays is achieved by multiple energy loss and time-of-flight
measurements. Bending inside the 0.15 T magnetic volume yields a measurement of
the absolute value of the particle's rigidity. The supplemental knowledge of
the sense of traversal identifies the sign of the charge. In the rigidity range
1 < R < 140 GV no antinucleus at any rigidity was detected, while 2.86 million
helium and 165 thousand heavy nuclei were precisely measured. Hence, upper
limits on the flux ratio antinuclei-to-nuclei are given. Different prior
assumptions on the antimatter spectrum are considered and corresponding limits
are given.
