Search for the proton decay mode p → ν K+ in Soudan 2

We have searched for the proton decay mode p --> nu K+ using the one-kiloton Soudan 2 high resolution calorimeter. Contained events obtained from a 3.56 kiloton-year fiducial exposure through June 1997 are examined for occurrence of a visible K+ track which decays at rest into mu(+)nu or pi(+)pi(0). We found one candidate event consistent with background, yielding a limit, tau/B(p --> nu K+)> 4.3 x 10(31) years at 90% CL with no background subtraction. (C) 1998 Published by Elsevier Science B.V. All rights reserved.