Measurement of the ²⁵Mg(α,n)²⁸Si reaction cross section at LNL

A recent sensitivity study demonstrated that the ²⁵Mg(α,n)²⁸Si is the reaction with the strongest impact on the synthesis of ²⁶Al during explosive Neon and Carbon burning in nucleosynthesis events in galaxies. In order to improve the experimental knowledge of the ²⁵Mg(α,n)²⁸Si cross section, a new direct measurement has been performed at Legnaro National Laboratories for alpha beam energies ranging from 3 to 5 MeV. Our targets were made of 95.75% enriched ²⁵MgO (70 μg/cm²) evaporated on a 1 mg/cm² gold backing. Reaction neutrons were detected with ten BC501 liquid scintillators positioned at 2 m from the target and covering the angular range from 17.5 to 106 degrees with respect to the beam direction. The neutron energy was measured with the time-of-flight (TOF) technique. Two LaBr₃:Ce detectors were placed close to the target chamber, in order to study the gamma radiation produced by the reaction. The pulse shape analysis (PSA) technique was used to perform gamma-neutron discrimination and to reduce the background due to uncorrelated gamma rays. The data analysis is still ongoing