Experimental investigation of the effect of ionization on the 51V(p,n)51Cr reaction

The investigation of the effects of atomic ionization on nuclear reactions is of prime importance for nuclear astrophysics. However, no direct experimental measurement of this effect using a plasma target could be done as of yet. In this regard, we measured for the first time the neutron yield of a (p,n) reaction taking place in a target having different states of ionization. The studied nuclear reaction in this work was 51V(p,n)51Cr, induced in a natural vanadium target exposed to an external, laser-driven proton beam. In the solid target case, we measured 91(26)% of the expected neutrons, but this rate dropped to 30(18)% when the target was ionized. This significant reduction remains unexplained, even after taking into account electron screening effects, the stopping power in the target, and target expansion. Our findings open new avenues for investigating how plasma ionization influences nuclear reactions in hot matter relevant for astrophysical environments.