We propose an experiment to search for a new gauge boson, A$^prime$, in $e^+e^-$ annihilation by means of a positron beam incident on a gas hydrogen target internal to the VEPP-3 storage ring. The search method is based on a missing mass spectra in the reaction $e^+e^-rightarrow gamma$ A$^prime$. It allows observation of the A$^prime$ signal independently of its decay modes and life time. The projected result of this experiment corresponds to an upper limit on the square of coupling constant $|f_{etext{A}{^prime}}|^2=1cdot 10^{-8}$ with a signal-to-noise ratio of five to one at an A$^prime$ mass of 15 MeV.
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