  In this paper, we adopt the method of quantum fields in curved spacetime to
quantize a free scalar matter field in the braneworld background whose warped
factor is of the form that could generate P\"{o}schl-Teller potential. Then we
consider the interaction between the scalar field $\phi(x)$ and a classical
scalar source $\rho(x)$ with the form
$\mathcal{H}_I=\sqrt{-g}\tilde{g}\rho(x)\phi(x)$. The corresponding S-matrix is
given and the number of particles generated by the source is obtained.
Furthermore, we get the {particle numbers} in the cases that only ground state
mode of the field could be detected and both the ground and first exited states
could be detected, respectively. Finally, by the particle number density we
define, we show how the extra dimension makes a difference specifically by the
excited modes.
