Recent results from PHENIX on double helicity asymmetry (ALL) measurement at √s = 510 GeV

الأصل · EN

One of the major objectives of the RHIC spin program at BNL is the measurement of the gluon helicity contribution, ΔG, to the proton spin via measuring the double longitudinal spin asymmetry (ALL) in various channels. In PHENIX (Pioneering High Energy Nuclear Interaction eXperiment) the ALL in π⁰, η, J/ψ etc. are measured in wide rapidity range. In this talk, ALL in π⁰ production in central rapidity and J/ψ production in forward rapidity will be discussed. The π⁰ is reconstructed through its diphoton decay channel within the rapidity range of | η| < 0.35 and azimuthal angle of 180∘. Similarly, J/ψ is reconstructed via dimuon decay channel within the rapidity range of 1.2 < | η| < 2.2. Preliminary results for ALL in π⁰ and J/ψ production from the data collected in the year 2013 at center of mass energy (√s) = 510 GeV will be presented. Also, their impact on ΔG 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 √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 π⁰ and 0.002 for J/ψ.