  Transverse momentum spectra of pions, kaons, protons and antiprotons from
Au+Au collisions at sqrt(s_(NN)) = 62.4 GeV have been measured by the PHOBOS
experiment at the Relativistic Heavy Ion Collider at Brookhaven National
Laboratory. The identification of particles relies on three different methods:
low momentum particles stopping in the first detector layers; the specific
energy loss (dE/dx) in the silicon Spectrometer, and Time-of-Flight
measurement. These methods cover the transverse momentum ranges 0.03-0.2,
0.2-1.0 and 0.5-3.0 GeV/c, respectively. Baryons are found to have
substantially harder transverse momentum spectra than mesons. The pT region in
which the proton to pion ratio reaches unity in central Au+Au collisions at
sqrt(s_(NN)) = 62.4 GeV fits into a smooth trend as a function of collision
energy. At low transverse momenta, the spectra exhibit a significant deviation
from transverse mass scaling, and when the observed particle yields at very low
pT are compared to extrapolations from higher pT, no significant excess is
found. By comparing our results to Au+Au collisions at sqrt(s_(NN)) = 200 GeV,
we conclude that the net proton yield at midrapidity is proportional to the
number of participant nucleons in the collision.
