Charged Particle Spectra from Au+Au $\sqrt{s_{NN}}=27$ GeV Collisions at STAR

The RHIC beam energy scan I (BES-I) ran from 2010 to 2014 and covered a range of energies from $\sqrt{ s_{NN} } $ = 62.4 to 7.7 GeV. Midrapidity spectra for $\pi$, $K$, and p have been published from those data. Those and other results have justified a new beam energy scan (BES-II) with high statistics and a series of detector upgrades. The first collider energy from BES-II, 27 GeV, was run in 2018. For this run a single sector of the inner time projection chamber (iTPC) upgrade was available. This detector upgrade extended the coverage of the STAR detector to lower $p_T$ and higher $\eta$. This talk will report the spectra and yields of $\pi$, $K$, and p as a function of rapidity and centrality from the 27 GeV Au+Au collisions from 2018 at the Relativistic Heavy Ion Collider. The relative yields of the various particle species allows one to measure the chemical freeze-out temperature and baryon chemical potential. The extended coverage provided by the iTPC upgrade will improve estimates of the full 4$\pi$ yields. The parameters extracted from the 4$\pi$ yields in the current analysis are compared to previous experimental results extracted from midrapidity particle yields to address the evolution of the baryon chemical potential as a function of rapidity.