P371 Experiment at CERN -- quest for polarized antiprotons

TL;DR

The paper addresses whether antiproton production in $pp$ collisions can generate a measurable polarization, potentially enabling polarized antiproton beams with existing facilities. It proposes measuring polarization via elastic $\\bar{p}p$ scattering in the Coulomb–nuclear interference region, leveraging a known analyzing power $A_y$ of a few percent and a detector system deployed on the CERN PS T11 line. The plan estimates about $1.6\\times 10^{6}$ events collected over ~8 weeks, corresponding to a few-percent level polarization sensitivity, thereby directly testing production-induced polarization. A positive result would have significant implications for hadronic spin physics and QCD studies using polarized antiprotons.

Abstract

Polarization effects in the production of antiprotons at the CERN PS beam line T11 at 3.5 GeV/c have been investigated within the P371 experiment. These effects, if found to be significant could provide a simple method to generate polarized antiproton beams with existing facilities. First precursor measurements were carried out by the P349 collaboration, though the available statistics were insufficient for a quantitative conclusion. With an upgraded detector setup and extended beam time, the experiment aims at determining whether a measurable degree of antiproton polarization exists.

Figures (1)

• Figure 1: Schematic view of the detector arrangement in the horizontal plane. The beam enters from the right and passes sequentially through the start scintillator, Cherenkov detector, scintillating fiber hodoscope, scattering target, straw tubes, DIRC, and scintillator plates.