Orateur
Description
The Extreme Light Infrastructure-Nuclear Physics (ELI-NP) facility will provide monochromatic, high-brilliance and polarized gamma-ray beams, which can be used to study nuclear reactions of current astrophysical interest through the inverse photo-dissociation processes and detailed balance principle. In particular, of special interest are (p, $\gamma$) and ($\alpha$, $\gamma$) reactions that regulate the ratio of C and O and those that burn $^{18}$O and, therefore, regulate the ratio between $^{16}$O and $^{18}$O in the Universe. For instance, the benchmark inverse kinematic reaction $^{12}$C($\gamma$, $\alpha$)$^{16}$O can be investigated down to 1 MeV in the centre-of-mass reference frame, where experimental data from direct experiments are sparse.
A dedicated Time Projection Chamber (ELITPC) with an active gaseous target kept under low pressure is being developed at University of Warsaw, IFIN-HH/ELI-NP and University of Connecticut. The active target volume of ELITPC will be about 35 $\times$ 20 $\times$ 20 cm$^3$ and will be centered around gamma-beam axis. The reaction products stopped in the gas will produce primary electrons that drift towards charge amplification structures made of Gas Electron Multiplier (GEM) foils. The three-dimensional kinematics of the photo-dissociation events will be reconstructed from about 10$^3$ signal strips, arranged into redundant, 3-coordinate system.
High intensity $\gamma$ beams are expected to be available at ELI-NP ($\sim$10$^7$ photons/bunch, 100 Hz bunch repetition rate). The beam-induced background has been studied using Monte Carlo techniques for different $\gamma$ beam profiles, in order to optimize the expected signal to background ratio. Several scaled demonstrator detectors were constructed and tested with alpha-particle and X-ray sources.
The results from ongoing R$\&$D activities for this project will be presented.
