Missing-mass spectroscopy of the C12(p,d) reaction near the η′ -meson production threshold

Excitation-energy spectra of $^{11}\mathrm{C}$ nuclei near the ${\ensuremath{\eta}}^{\ensuremath{'}}$-meson production threshold have been measured by missing-mass spectroscopy using the $^{12}\mathrm{C}(p,d)$ reaction. A carbon target has been irradiated with a 2.5 GeV proton beam supplied by the synchrotron SIS-18 at GSI to produce ${\ensuremath{\eta}}^{\ensuremath{'}}$-meson bound states in $^{11}\mathrm{C}$ nuclei. Deuterons emitted at ${0}^{\ensuremath{\circ}}$ 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 ${\ensuremath{\eta}}^{\ensuremath{'}}$-mesic states is observed although a high statistical sensitivity is achieved in the experimental spectra. Upper limits on the formation cross sections of ${\ensuremath{\eta}}^{\ensuremath{'}}$-mesic states are determined, and thereby a constraint imposed on the ${\ensuremath{\eta}}^{\ensuremath{'}}$-nucleus interaction is discussed.