Bound Diproton: An ``Illusive'' Particle or Exotic Nucleus?
I.M. Kadenkoa, b, B.M. Bondarb, c, O.M. Gorbachenkob, N.V. Sakhnoa, b
aInternational Nuclear Safety Center of Ukraine, Taras Shevchenko National University of Kyiv, St. Volodymyrs'ka, 64/13, 01601, Kyiv, Ukraine
bDepartment of Nuclear and High Energy Physics, Faculty of Physics, Taras Shevchenko National University of Kyiv, St. Volodymyrs'ka, 64/13, 01601, Kyiv, Ukraine
cRadiopharmaceutical Production Department, Clinical Hospital ``Feofaniya'', St. Zabolotnogo, 21, 03143 Kyiv, Ukraine
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This paper considers the possible existence of a bound diproton. The study was inspired by the predictions of Migdal (Sov. J. Nucl. Phys. 16, 238 (1973)), who solved a theoretical task for two identical particles to become bound in the potential field established by heavy nuclei. Earlier, the possibility of bound particles was confirmed experimentally in the case of the dineutron. We report the search for a bound diproton, or 2He nucleus, analyzing the results of irradiation of several samples with protons with energies just below the thresholds in the corresponding (p,2p) nuclear reaction channel. The irradiated 159Tb and 181Ta samples were then counted by applying an HPGe gamma-spectrometer and featured a significant intensity of the 511 keV gamma-ray peaks. After acquiring data sets with peak intensities versus sample cooling times, the results were fitted with one or two exponential functions, and two experimentally determined half-lives were obtained for Ta sample, i.e., 6336±220 s and 1224±40 s. These values were in good agreement with the results of theoretical calculation based on the assumption of the 384 keV binding energy of the diproton. In addition, the radius and possible configuration and reaction mechanism were estimated and presented to serve together as a preliminary basis for confirming the existence of a bound diproton.

DOI:10.12693/APhysPolA.142.337
topics: diproton, positron decay, diproton half-life