The Study of the $^{22}$Ne(α,γ)$^{26}$Mg Reaction at LUNA

The $^{22}$Ne(α,γ)$^{26}$Mg reaction is the competitor of the $^{22}$Ne(α,n) $^{25}$Mg reaction, an effective neutron source for element synthesis through s-process. Currently the ratio between the rates of these two reactions is affected by high uncertainty because of the wide range of values proposed for the $^{22}$Ne(α,γ)$^{26}Mg 395 keV resonance strength (10$_{-15}$ -10$^{−9} eV). The present study represents the first direct measurement. This was performed at the ultra-low background LUNA laboratory where an high efficiency detector was installed at the gas target beamline of LUNA 400kV accelerator. The Ne gas, 99% enriched in $^{22}$Ne, was irradiated with a 399.9 keV α-beam. No significant signal was detected in the 22 Ne(α,γ)$^{26}$Mg region of interest, thus an upper limit for the 395 keV resonance strength was estimated.