$$\alpha $$ induced reactions for nuclear astrophysics at sub-barrier energies

Abstract Reactions induced by alpha particles, which play an important role in nuclear astrophysics, were investigated at energies below the Coulomb barrier using our IFIN-HH facilities. These include the 3 MV Tandetron™ accelerator [1], a local laboratory and the ultra-low background laboratory $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> Bq [2] located in a salt mine. Thick Zn metal targets were irradiated at laboratory energies in the range $$\hbox {E}_{\alpha }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>E</mml:mtext> <mml:mi>α</mml:mi> </mml:msub> </mml:math> = 5.4–8.0 MeV in 0.20 or 0.25 MeV steps. By measuring the prompt gamma-ray yields and the decay of radioisotopes produced in each reaction, in the Nuclear Astrophysics Group (NAG) and the $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> Bq laboratories [3], we determined the thick target yields, which were subsequently used to evaluate the reaction cross sections. We succeeded in determining the cross section for $$\alpha $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>α</mml:mi> </mml:math> + 64 Zn for the proton evaporation and radiative alpha capture channels at the lowest energies ever measured, deep inside the Gamow window for stellar processes at temperatures of 2–3 GK.