Speaker
Description
As a part of the studies of the small systems ($p$, $d$, and $^3\text{He}+\text{Au}$), in this poster we present the preliminary yields of $\pi^0$ and direct $\gamma$ for the $\sqrt{s_{NN}}=200$ GeV $^3\text{He}+\text{Au}$ PHENIX data, as well preliminary nuclear modification factor ($R_{xA}$) for this system. We will discuss the unfolding procedure to obtain such yields from raw data in a way to account for $p_T$ migration as well as correct for detector acceptance and efficiency. For the nuclear modification factor, we employ the double ratio $R_{xA}=(\gamma^{dir}/\pi^0)_{pp}/(\gamma^{dir}/\pi^0)_{xA}$ which can be shown to be analytically equivalent to the regular expression for $R_{xA}$, but using an experimentally determined metric for the number of binary collisions ($N_{coll}^{exp}=\gamma_{xA}^{dir}/\gamma_{pp}^{dir}$). As we will show, using this ratio has the advantage of canceling systematic uncertainties that are present in both $p+p$ and $^3\text{He}+\text{Au}$ collisions (such as the reduced production of high $p_T$ pions and $\gamma^{dir}$ due to cold nuclear matter effects and uncertainties due to the $p+p$ cross section), as well as detaching the nuclear modification factor from the Glauber model, thus minimizing biases on centrality determination which are particularly relevant for the studies of small systems.
| Category | Experiment |
|---|---|
| Collaboration (if applicable) | PHENIX |
