Determination of the COSY proton beam polarization using the WASA detector

The dynamics of $\eta$ -meson production and the interaction of $\eta$ mesons with nucleons can be studied using the $\vec{p}p\rightarrow pp\eta$ reaction via measurements of the analyzing power $A_{y}$. To this end, we have performed a measurement of the $\vec{p}p\rightarrow pp\eta$ reaction using the WASA-at-COSY detector, which provides large acceptance and is $\varphi$ -symmetric. The experiment was carried out for the beam momenta of 2026 MeV/c and 2188 MeV/c. In this article, we present a method and results for the determination of the degree of the beam polarization