Characterization and first test of an i-TED prototype at CERN n_TOF

Neutron capture cross section measurements are of fundamental importance for the study of the slow process of neutron capture, so called s-process. This mechanism is responsible for the formation of most elements heavier than iron in the Universe. To this aim, installations and detectors have been developed, as total energy radiation C 6 D 6 detectors. However, these detectors can not distinguish between true capture gamma rays from the sample under study and neutron induced gamma rays produced in the surroundings of the setup. To improve this situation, we propose (Domingo Pardo in Nucl Instr Meth Phys Res A 825:78-86, 2016, [1]) the use of the Compton principle to select events produced in the sample and discard background events. This involves using detectors capable of resolving the interaction position of the gamma ray inside the detector itself, as well as a high energy resolution. These are the main features of i-TED, a total energy detector capable of gamma ray imaging. Such system is being developed at the "Gamma Spectroscopy and Neutrons Group" at IFIC (http://webgamma.ific.uv.es/gamma/es/, [2]), in the framework of the ERC-funded project HYMNS (High sensitivitY and Measurements of key stellar Nucleo-Synthesis reactions). This work summarizes first tests with neutron beam at CERN n _ TOF.