Excitation-energy spectra of $^{11}$C nuclei near the $eta^prime$-meson production threshold have been measured by missing-mass spectroscopy using the $^{12}$C($p$,$d$) reaction. A carbon target has been irradiated with a 2.5 GeV proton beam supplied by the synchrotron SIS-18 at GSI to produce $eta^prime$ meson bound states in $^{11}$C nuclei. Deuterons emitted at $0^circ$ in the reaction have been momentum-analyzed by the fragment separator (FRS) used as a high-resolution spectrometer. No distinct structure due to the formation of $eta^prime$-mesic states is observed although a high statistical sensitivity is achieved in the experimental spectra. Upper limits on the formation cross sections of $eta^prime$-mesic states are determined, and thereby a constraint imposed on the $eta^prime$-nucleus interaction is discussed.
تحميل البحث