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The energy spectrum for high energy ␥ rays (E ␥ у10 MeV͒ from the process pp→␥␥X emitted at 90°in the laboratory frame has been measured at an energy below the pion production threshold, namely, at 216 MeV. The resulting photon energy spectrum extracted from ␥-␥ coincidence events consists of a narrow peak at a photon energy of about 24 MeV and a relatively broad peak in the energy range of 50Ϫ70 MeV. The statistical significances for the narrow and broad peaks are 5.3 and 3.5, respectively. This behavior of the photon energy spectrum is interpreted as a signature of the exotic dibaryon resonance d 1 Ã with a mass of about 1956MeV, which is assumed to be formed in the radiative process pp→␥d 1 Ã followed by its electromagnetic decay via the d 1 Ã →pp␥ mode. The experimental spectrum is compared with those obtained by means of Monte Carlo simulations.

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The possibility of using the bremsstrahlung reaction in proton-proton interactions as a new tool for searching and investigating the narrow, exotic 6-quark(di-nucleon) resonances is suggested and discussed.

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