  Identified mid-rapidity particle spectra of $\pi^{\pm}$, $K^{\pm}$, and
$p(\bar{p})$ from 200 GeV p+p and d+Au collisions are reported. This data were
taken in 2003 run from the Solenoidal Tracker at RHIC (STAR) experiment. A
time-of-flight detector based on multi-gap resistive plate chamber (MRPC)
technology is used for particle identification. The intrinsic timing resolution
85 ps was achieved after the calibration. We observe that the spectra of
$\pi^{\pm}$, $K^{\pm}$, $p$ and $\bar{p}$ are considerably harder in d+Au than
those in p+p collisions. In $\sqrt{s_{_{NN}}} = 200$ GeV d+Au collisions, the
nuclear modification factor $R_{dAu}$ of protons rise faster than those of
pions and kaons. Besides, the particle-species dependence of the Cronin effect
is observed to be significantly smaller than that at lower energies. The ratio
of the nuclear modification factor ($R_{dAu}$) between $(p+\bar{p})$ and
charged hadrons ($h$) in the transverse momentum range $1.2<p_{T}<3.0$ GeV/c is
measured to be $1.19\pm0.05$(stat)$\pm0.03$(syst) in minimum-bias collisions
and shows little centrality dependence. The yield ratio of $(p+\bar{p})/h$ in
minimum-bias d+Au collisions is found to be a factor of 2 lower than that in
Au+Au collisions, indicating that the relative baryon enhancement observed in
heavy ion collisions at RHIC is due to the final state effects in Au+Au
collisions. The mechanism for Cronin effect is also discussed in this thesis by
comparison with the recombination model and with the initial multiple parton
scattering model. From the comparisons, we conclude that the Cronin effect in
200 GeV d+Au collisions is not initial state effect only, and that final state
effect plays an important role.
