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تسجيل مستخدم جديدTransparency ratio in gamma A -> eta A and the in-medium eta width
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The photoproduction of eta-mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500 - 2200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of eta-mesons in nuclei. The comparison indicates a width of the eta -meson of the order of Gamma= 15-25 MeV at rho =rho_0 for an average momentum p_{eta} = 1050 MeV/c, at which the eta-meson is produced in the nuclear rest frame. The inelastic eta N cross section is estimated to be 3 - 10 mb. Parameterizing the photoproduction cross section of eta-mesons by sigma(A) = sigma_0 A^{alpha}, a value of alpha = 0.84pm0.03 has been deduced.
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