Subthreshold Production of Low Momentum ${\mathit{K}}^{+}$ in $\mathit{p}+C$ at 1.2 GeV

The double differential cross section of low momentum kaons ( $\le 0.3\mathrm{GeV}/c$) from $p+\mathrm{C}$ collisions at subthreshold bombarding energies has been for the first time measured by the use of the CLAMSUD magnetic spectrometer installed at the CELSIUS storage ring. Invariant cross sections extracted from the data show a source rapidity shifted below the nucleon-nucleon rapidity, in agreement with the existence of multistep processes in the $K^{+}$ production cross section. The total cross section of the inclusive reaction ${}^{12}\mathrm{C}\left({p,K}^{+}\right)$ at 1.2 GeV was extracted and compared with recent data systematics as a function of the proton bombarding energy.