Formation of bound dineutrons in the ¹⁷⁵Lu (n, ²n) ¹⁷⁴ᵍLu nuclear reaction and its cross section

Background: The dineutron as a bound chargeless nucleus of two identical nucleons has been attracting attention for many decades. In addition to the study of the formation of a bound dineutron in the outgoing channel of some specific nuclear reactions, cross section estimates have been gaining interest as research target. Purpose: The dineutron under consideration is a bound system to be formed within the potential well of heavy nucleus beyond their volume by occupying several discrete energy levels [0 ÷ 0.4] MeV deep into the well by two neutrons in the outgoing channel of nuclear reaction when escaping from compound nucleus. Methods: We used a traditional neutron activation technique to irradiate Lu samples followed by measurements of the induced activity with HPGe spectrometer in order to detect gamma-peaks of the ¹⁷⁵Lu (n, 2n)¹⁷⁴ᵍLu reaction product when this reaction channel is not open for incident neutron energies. Results: Based on two measurements of the instrumental gamma ray spectra of Lu samples we reliably identified the presence of namely ¹⁷⁴ᵍLu isotope in the outgoing channel of the ¹⁷⁵Lu(n, ²n)¹⁷⁴ᵍ Lu nuclear reaction. Also, the cross section for this nuclear reaction was obtained and to be equal 33.5 ± 5.9 mb. Conclusions: For the first time, the dineutron as a nuclear reaction product was indirectly detected via statistically significant observation of the induced activity of ¹⁷⁴ᵍLu with corresponding cross-section estimate.