Experimental determination of the electron screening potential energy for the d(d, n)³He Reaction in ZrD₂ and D₂O in the ultralow energy region

This work is devoted to measuring of the values of the astrophysical S-factors and electron screening potential energy for a d(d,n)³He reaction occurring at ultralow energies in zirconium deuteride ZrD₂ (3.5-7.0 keV) and heavy water D₂O (2.2-6.0 keV). The experiment was performed on the Hall pulsed plasma accelerator at the TPU Nuclear Physics Institute (Tomsk) with ZrD₂ and D₂O targets produced by the magnetron sputtering of zirconium in a deuterium environment and heavy water freezing-out on a copper support, respectively. A Χ analysis of the dependence of the neutron yields and astrophysical S-factors for the dd reaction on the deuteron collision energy E revealed that the upper bounds of the electron screening potential energy for interacting deuterons in ZrD₂ and D₂O and of the astrophysical S-factors at the deuteron collision energy E = 0 were U_e(ZrD₂) < 30 eV, U _e(D₂O) < 25 eV, S(0) = (57.2 ± 3.9) keV • b (ZrD₂), S(0) = (58.6 ± 3.6) keV • b (D₂O) at the 90% confidence level.