  We investigate the squeezed back-to-back correlations (BBC) of $K^+$$K^-$,
caused by the mass modification of the particle in the dense medium formed in
d+Au collisions at $\sqrt{s_{NN}}=200$ GeV and Au+Au collisions at
$\sqrt{s_{NN}}=62.4$ GeV. Considering some kaons may be not affected by the
medium, we further study the BBC functions of $K^+$$K^-$ when parts of all
kaons have a mass-shift. Our results indicate that the BBC functions of
$K^+$$K^-$ can be observed when only about 10$\%$ of all kaons have a
mass-shift in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV and the peripheral
collisions of Au+Au at $\sqrt{s_{NN}}=62.4$ GeV. Since the BBC function is
caused by the mass-shift due to the interaction between the particle and the
medium, the successful detection of the BBC function indirectly marks that the
dense medium has formed in these collision systems. We suggest to measure the
BBC function of $K^+$$K^-$ experimentally in d+Au collisions at
$\sqrt{s_{NN}}=200$ GeV and peripheral collisions of Au+Au at
$\sqrt{s_{NN}}=62.4$ GeV.
