Speaker
Hari Guragain
(PHENIX Collaboration)
Description
One of the major objectives of the RHIC spin program at BNL is the
measurement of the gluon helicity contribution, $\Delta G$, to the proton spin via
measuring the double longitudinal spin asymmetry ($A_{LL}$) in various
channels. In PHENIX (Pioneering High Energy Nuclear Interaction
eXperiment) the $A_{LL}$ in $\pi^{0}$, $\eta$, $J/\psi$ etc. are measured in wide rapidity range. In this talk, $A_{LL}$ in $\pi^{0}$ production in central rapidity and $J/\psi$ production in forward rapidity will be discussed. The $\pi^{0}$ is reconstructed through its diphoton decay channel within the rapidity range of $\left| \eta \right|$ $<$ 0.35 and azimuthal angle of
$180\,^{\circ}$. Similarly, $J/\psi$ is reconstructed via dimuon decay channel within the rapidity range of 1.2 $<$ $\left| \eta \right|$ $<$ 2.2. Preliminary results for $A_{LL}$ in
$\pi^{0}$ and $J/\psi$ production from the data collected in the year 2013 at
center of mass energy ($\sqrt{s}$) = 510 GeV will be presented. Also, their impact on $\Delta G$ constraint will be discussed. In year 2013, the total
integrated luminosity was 150 $pb^{-1}$ which is almost ten times the
total luminosity recorded in the year 2009 at $\sqrt{s}$ = 200 GeV.
Due to increase in the center of mass energy and integrated
luminosity, the new measurements can cover the Bjorken x range down to
0.01 for $\pi^{0}$ and 0.002 for $J/\psi$.
Author
Hari Guragain
(PHENIX Collaboration)
