The new facility, Extreme Light Infrastructure – Nuclear Physics (ELI-NP), is a combined laser-gamma nuclear physics research facility currently undergoing its final implementation stages in Măgurele near Bucharest, Romania. It already hosts two fully-operational 10 PW laser arms and, by 2023, it will also house a γ-beam system based on laser Compton backscattering, capable of delivering a high-brilliance, low-energy beam at E γ ≲ 19.5 MeV. Owing to this unique laser-gamma instrumentation combination, several types of experiments will be possible at ELI-NP, including high precision nuclear resonance fluorescence (NRF) experiments. In this case, the main γ-beam detection system for performing NRF studies at ELI-NP is represented by the ELI Array of DEtectors (ELIADE), featuring eight high-purity germanium (HPGe) segmented clover detectors. The current work presents the characteristics of two of the ELIADE detectors, including their photopeak detection efficiency, energy resolution, and peak-to-total ratio measured using γ-ray sources, as well as the timing performance obtained via in-beam measurements. For these latter detector tests, 130La was populated via the fusion evaporation reaction 121Sb(12C,3n)130La using a beam energy of 53 MeV at the Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), also located in Măgurele. Herein, we report on the results of the ^130La linear polarization measurements taken using the ELIADE detectors as Compton polarimeters. The results obtained from the in-beam experiment were compared to several already published works and we present new information on the transition multipolarity in 130La.

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We describe the status of a project for obtaining an intense beam of polarized slow positrons at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) at Magurele (near Bucharest, Romania) [1]. Positrons will be created via pair production and moderated at a tungsten target using the pulsed brilliant gamma beam which will be produced by Compton back-scattering of circularly polarized laser photons on electrons from a warm linac beam [2]. Simulations of the interaction of circularly polarized γ‑rays of energies up to 3.5 MeV and an intensity of 2.4×1010γ/s with the target, moderation of created positrons and beam formation are discussed. The optimization of the target design showed that the primary slow positron beam can be obtained with intensity of 1‑2×106e+/s. The primary beam will be transversally polarized with a degree of polarization of ~30%. We discuss the necessity of changing the e+ beam polarization from transversal to longitudinal by an electrostatic 90˚ bender which is proposed to work in combination with a remoderator. Simulations show that neither the remoderator nor the electrostatic bender will change the degree of e+ beam polarization. The longitudinally polarized e+ can be successfully transported to the sample chambers without depolarization, but with reduced intensity (by approximately one order of magnitude) due to the remoderation. We present a convertor-moderator assembly with a hole which will allow creating positrons in parasitic mode, i.e., simultaneously with the nuclear physics experiments at ELI-NP. The positron spectroscopy laboratory at ELI-NP will be user dedicated and the beam will have the highest intensity of polarized slow positrons for material science in the world and therefore it could become a unique tool for investigation of magnetic samples.