Study of the Polarization Deterioration During Physics Stores in RHIC Polarized Proton Runs

Z Duan,Q Qin,T Roser,M Bai

doi:10.1142/s2010194516600910

Abstract

As the only high energy polarized proton collider in the world, the Relativistic Heavy Ion Collider (RHIC) has achieved a great success in colliding polarized proton beams up to 255GeV per beam energy with over 50% average store polarizations for spin physics studies. With the help of Siberian snakes as well as outstanding beam control during the acceleration, polarization loss during acceleration up to 100 GeV is negligible. However, about 10% polarization loss was observed between acceleration from 100 GeV to 255 GeV. In addition, a mild polarization deterioration during long store for physics data taking was also observed. In this paper, studies in understanding the store depolarizing mechanism is reported, including the analysis of polarization deterioration data based on the past couple of RHIC polarized proton runs.

Highlights

The Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory was designed to provide colliding beams of polarized protons up to a beam energy of 250GeV.[1]
Two p-Carbon polarimeters are currently in use for each RHIC ring, about four measurements of the beam polarization are taken for each physics store
We present our analysis of the RHIC polarization data for past few runs, to understand the physical mechanisms of the observed polarization deterioration in RHIC physics stores

Summary

Introduction

The Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory was designed to provide colliding beams of polarized protons up to a beam energy of 250GeV.[1]. The H-jet polarimeter[2] is designed This is an Open Access article published by World Scientific Publishing Company. Two p-Carbon polarimeters are currently in use for each RHIC ring, about four measurements of the beam polarization are taken for each physics store. In past few polarized proton runs, colliding proton beams up to 255GeV with above 50% average store polarization have been supplied for physics data taking.[6]. For run[13] with the elens lattice, there is a large difference between the polarization decay rates for the two beams. Average H-jet polarization for different RHIC polarized proton runs blue ring yellow ring run11:250GeV run12:100GeV run12:255GeV run13:elens run13:run[12]

Theoretical Formalism

Findings

Conclusion