Orientation effect in the neutron yield in deuterated Pd target bombarded by deuterium ion beam

Abstract

At the ion accelerator HELIS at the LPI, the neutron yield is investigated from a deuteron-deuteron (DD) reaction in a deuterated Pd target, during an irradiation of its surface by a 20 keV deuterium (D) ion beam. The measurements of the neutron flux in the D beam direction are performed in dependence on the target angle β with respect to the D beam axis using a multichannel detector based on He 3 counters. A significant anisotropy in the neutron yield is observed, and it was higher by a factor of 2 at β ¼ 0 compared to that at β ¼ AE30°. The possible reasons for the anisotropy, including D ion channeling, are discussed. The orientation effect of increasing the relative probability of the DD reaction in Pd due to channeling was investigated by computer simulations using the BCM-2.0 code. The numerically obtained 20 keV D trajectories allow calculating the flux density of channeled D in dependence on the penetration depth and angle of incidence. The enhanced D flux density between crystal planes at a zero incident angle with respect to (200) Pd planes allows a qualitative explanation of the increase of the neutron yield in the DD reaction.

Investigation of the interaction of the ion beams with deuterated crystal structures at the HELIS facility

“…The channeling of deuterium ions in a diamond target does not, however, explain the noticeable difference in the neutrons yield from DD reaction along and across the direction of the incident D beam, which is the subject for further investigations. Similar measurements were performed on the Pd/PdO:D x target [23]: here, the orientation effect and the neutron yield anisotropy along and across the direction of the ion beam were also noticeable (figure 3b), which allows to assume that, in addition to the deuterium beam ions channeling there possibly exists a fast neutrons channeling within the crystalline targets generated as a result of nuclear reactions in the channels of the crystalline target. And indeed, the fast neutrons channeling effect had been reported in [24] when a Ge crystal was irradiated by the reactor neutrons.…”