Hadron structure cannot be understood without unraveling spin structure. This fact has been acknowledged in the recent assessment of the EIC Science by National Academy of Sciences by identifying the understanding the origin of the internal angular momentum or spin of nucleons, as one of the three central scientific issues that would be addressed by an EIC. While past or existing DIS experiments were and are very successful in determining the polarized quark structure of the nucleon and of some light nuclei, none matches the unique capabilities of an EIC by being able to change at the same machine between longitudinal, transverse, and (for deuteron only) tensor polarization states and with being able to collide polarized electron beams with polarized protons, deuteron, and Helium-3 beams over a broad kinematic range.
The proposed Electron-Ion Collider (EIC) will present the opportunity to achieve unprecedented statistical precision in many reaction channels studying the spin structure of nucleons. Given this high precision, it is imperative that the forthcoming results achieve systematic uncertainties at a comparable level. In particular, knowledge of the electron and hadron beam polarization is likely to be a limiting systematic uncertainty for many single-spin and double-spin asymmetry measurements. Polarimetry approaching the 1% level is desired, yet presents many fundamental and practical challenges.
Attaining high polarization level of electron, proton and light ion beams in the EIC rests both on experience from previous polarized beam accelerators and on novel approaches. EIC accelerator design has to fully address challenges of various spin depolarizing mechanisms and provide efficient polarization direction control at experimental areas.
The generation of polarized beams and the evolution of the beam polarization as the beam propagates through the machine are of course closely coupled with polarimetry. Accurate polarimetry provides valuable feedback for setup and tuning of the accelerator, while knowledge of the machine properties that impact beam polarization is important for accurate and precise polarization measurements.
The aim of this proposed workshop is to bring together experts in electron and hadron beam polarimetry as well as experts in polarized beams in accelerators.
In the event that travel is still restricted in June due to the COVID-19 virus, we will plan to hold the workshop online. This way we can keep with the Yellow Report timeline, as established by the EIC Users Group, and provide timely impact on the EIC machine design.