SPIN 2018

Precise measurements of the single and double spin-flip asymmetries in CNI region in elastic proton-proton scattering at √s=13.7 GeV and √s=21.9 GeV at RHIC HJET polarimeter.

12 Sept 2018, 15:30

20m

A9 (Polo degli Adelardi - Via Adelardi, 33)

Parallel Sessions Acceleration, Storage and Polarimetry of Polarized Beams Acceleration, Storage and Polarimetry of Polarized Beams

Speaker

Dr Andrei Poblaguev (Brookhaven National Laboratory)

Description

The Polarized Atomic Hydrogen Jet Target polarimeter (HJET) is employed by Relativistic Heavy Ion Collider (RHIC) to measure absolute polarization of the colliding proton beams. In RHIC Runs 2015 (E_beam=100 GeV) and 2017 (E_beam=255 GeV) we accumulated large statistics of about 10^9 events per beam per run for elastic polarized proton scattering on polarized target (HJET) protons for the momentum transfer range 0.0015<-t<0.018 GeV^2. Such statistics allowed us to measure single spin, A_N, and double spin, A_NN, analyzing powers with unprecedented statistical accuracy and very low systematic uncertainty (of order of statistical errors). For the first time hadronic single spin-flip r_5 and double spin-flip r_2 amplitudes were reliably isolated at these energies. The preliminary results (statistical errors only) are Re⁡r_5=(-16.4±1.1)×10^(-3), Im⁡r_5=(3.1±4.0)×10^(-3), Re⁡r_2=(-3.58±0.28)×10^(-3), Im⁡r_2=(-0.09±0.12)×10^(-3) for √s=13.7 GeV and Re⁡r_5=(-6.7±0.5)×10^(-3), Im⁡r_5=(19.2±2.4)×10^(-3), Re⁡r_2=(-2.37±0.22)×10^(-3), Im⁡r_2=(0.38±0.08)×10^(-3) for √s=21.9 GeV. Measurements at 2 beam energies allowed us to separate Pomeron and Regge-pole contributions to the hadronic single- and double- spin-flip amplitudes. No indication of Odderon contribution was found. Extrapolation of the measured A_N (t,s) to √s=200 GeV is in a good agreement with STAR measurements at this energy.

Presentation materials

Slides

2018.09.12_SPIN18.pdf