Neutron production yield in alpha induced reactions on CaF2 and 27Al

Low energy (α,n) reactions are important for reactor applications and low background experiments. In both cases α-particles, typically of a few MeV, originated from actinides decay present either in reactor fuel and/or in surrounding materials due to the elemental natural abundance. The emitted thus α-particles can induce nuclear reactions on nuclei of wide range of materials introduced in the given experimental environment such as $^{13}$C, $^{19}$F, $^{16}$O, $^{18}$O, $^{27}$Al, $^{29}$Si, $^{30}$Si, etc. Because of the considerable cross-sections in the indicated energy range, up to barns, the resulted neutron yield is significant and should be properly taken in the consideration. Neutron detector systems based on proportional $^{3}$He counters provide high efficiency and almost full angular coverage which makes it the ideal candidate for reaction cross-section measurements, including (α,n) reactions. The ELIGANT-TN [1] array constructed at Extreme Light Infrastructure-Nuclear Physics (ELI-NP), Măgurele, Romania was originally aimed at (γ, n) cross-section studies. It consists of 28 $^{3}$He counters arranged in three rings in the high-density polyethylene matrix, shielded by a cadmium layer from background neutrons, in a way to reach a flat efficiency of $\sim$37% up to $\sim$5 MeV neutron energy. One more advantage of such a detector is the possibility to measure the average neutron energy by the ring ratio technique. Lately, ELIGANT-TN was installed at the experimental hall of the 3 MV Tandetron facility of Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH) Măgurele, Romania [2]. The accelerator provides intense low-energetic charged particles beams. In our first experiments the cross-sections of $^{19}$F(α,n), $^{13}$C(a,n) and $^{27}$Al(α,n) in the $\sim$3–7 MeV energy range were investigated. Moreover, recently, in November 2023, an experiment to measure the $^{19}$F(α,n) and $^{13}$C(α,n) cross-sections up to 17 MeV was undertaken. α-beam was delivered by the 9 MV Pelletron Tandem Accelerator (IFIN-HH) [3]. In the talk it will be presented the design and performance of the ELIGANT-TN array. The preliminary experimental results/questions of our experiments and future perspectives will be discussed.