First results from subthreshold K+-production measurements with ANKE

The new spectrometer ANKE has been put into operation at the accelerator CO SY of the Forschungszentrum Julich. An initial scientific goal is to study K+-production in pA collisions at subthreshold energies below the free NN-t hreshold of T = 1.58 GeV. First measurements of double differential cross s ections in p(12)C collisions at emission angles around 0 degrees have been performed at T = 1.0, 1.2 and 2.0 CeV. The challenge is to identify the kao ns in a huge background of pions and protons, since the signal to backgroun d ratio decreases to about 10(-6) at T = 1.0 GeV. For background suppressio n detectors and a trigger system based on energy-loss and time-of-flight me asurements have been developed. In the analysis the decay of kaons (tau = 1 2.4 ns) stopped in the detection system into mu(+) and pi(+) is exploited a s well as the track information from the wire chambers.