We have measured the ionization efficiency of silicon nuclear recoils with kinetic energy between 1.8 and 20 keV. We bombarded a silicon-drift diode with a neutron beam to perform an elastic-scattering experiment. A broad-energy neutron spectrum was used and the nuclear recoil energy was reconstructed using a measurement of the time of flight and scattering angle of the scattered neutron. The overall trend of the results of this work is well described by the theory of Lindhard et al. above 4 keV of recoil energy. Below this energy, the presented data shows a deviation from the model. The data indicates a faster drop than the theory prediction at low energies. I IntroductionThe development of technologies for detecting low energy nuclear recoils has been a very active field in recent years, mainly driven by dark matter searches and coherent neutrino nucleus scattering (CENNS) experiments. When a nucleus recoils in a semiconductor detector, it loses its kinetic energy through two mechanisms: the generation of free charge carriers by ionization and the production of phonons by collisions with the lattice atoms. The partition of energy is quantified by the ionization efficiency, ε, defined as the ratio of the energy lost via ionization, E i , to the kinetic energy of the nuclear recoil, E N R . In the literature, E i is usually denoted by eV

The total cross section of the 12 C+ 16 O fusion reaction has been measured at low energies to investigate the role of this reaction during late stellar evolution burning phases. A high-intensity oxygen beam, produced by the 5MV pelletron accelerator at the University of Notre Dame, impinged on a thick, ultra-pure graphite target. Protons and γ-rays were simultaneously measured in the center-of-mass energy range from 3.64 to 5.01 MeV for singles and from 3.73 to 4.84 MeV for coincidence events, using silicon and Ge detectors. Statistical model calculations were employed to interpret the experimental results. The emergence of a new resonance like broad structure and a decreasing trend in the S-factor data towards lower energies (opposite to previous data) are found for the 12 C+ 16 O fusion reaction. Based on these results the uncertainty range of the reaction rate within the temperature range of late stellar burning environments is being discussed .

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