EXA2011

The preparation of an intense beam of polarized antiprotons is {\it the} crucial point for the physics program proposed by the PAX collaboration [1] at the future FAIR facility in Darmstadt. A possibility to overcome this experimental challenge is seen in elastic scattering of antiprotons off a polarized $^1$H target [2]. Another possibility is to use the interaction of antiprotons with a polarized deuterium target [3]. As was shown in Ref. [3] on the basis of the Glauber theory with elementary {$\bar p N$} amplitudes taken from the J\"ulich models of the $\bar N N$ interaction [4], the ${\bar p}{\vec d}$ interaction could provide similar or even more effective polarization of the antiprotons as the $\bar p p$ interaction. This conjecture can be checked at a planned AD experiment [5]. The next step is to study scattering of antiprotons off a polarized $^3{\rm He}$ target. Since the polarization of the $^3{\rm He}$ is carried mainly by the neutron, the $\bar p n$ amplitudes are expected to dominate the spin observables of this reaction. In the present work we calculate spin-dependent cross sections of $\bar p ~^3{\rm He}$ interaction on the basis of an approach similar to that developed in Ref.~[3]. In order to check the validity of the Glauber approximation at low energies we calculated also the $\bar p ~^4{\rm He}$ differential cross section at 600 MeV/c beam momentum and its total annihilation cross section at 200 MeV/c and 600 MeV/c, where data are available, and found good agreement with the measurements. The calculated annihilaton cross section for $\bar p ~^3{\rm He}$ is also in agreement with the available data [6] at 200 MeV/c. The polarization efficiency for $\bar p ~^3{\rm He}$ is estimated within the single-scattering approximation. [1] V.~Barone {\it et al.} [PAX Collaboration], arXiv:hep-ex/0505054. [2] F. Rathmann {\it et al.}, Phys.\ Rev.\ Lett. {\bf 94} (2005) 014801. [3] Yu.N.~Uzikov, J.~Haidenbauer, Phys. Rev. C {\bf 79} (2009) 024617. [4] T.~Hippchen, J.~Haidenbauer, K.~Holinde, V.~Mull, Phys. Rev. C {\bf 44} (1991) 1323. [5] C.~Barschel {\it et al} [PAX Collaboration], arXiv:0904.2325[nucl-ex]. [6] F. Balestra {\it et al.}, Phys. Lett. B {\bf 215} (1988) 247.