Double Spin Asymmetries A_NN and A_SS at sqrt{s}=200 GeV in Polarized   Proton-Proton Elastic Scattering at RHIC
  We present the first measurements of the double spin asymmetries A_NN and A_SS at sqrt{s}=200 GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). The data were collected in the four momentum transfer t range 0.01<|t|<0.03 (GeV/c)^2. The measured asymmetries, which are consistent with zero, allow us to estimate upper limits on the double helicity-flip amplitudes phi_2 and phi_4 at small t as well as on the difference Delta(sigma_T) between the total cross sections for transversely polarized protons with antiparallel or parallel spin orientations. 
pp2pp Collaboration: S. Bultmann, I.H. Chiang, R.E. Chrien, A. Drees,   R.L. Gill, W. Guryn, J. Landgraf, T.A. Ljubicic, D. ...