Speaker
Description
GRAPhEME is a $\gamma$ spectrometer developed by CNRS/IPHC Strasbourg (France), in collaboration with EC-JRC/Geel (Belgium) and IFIN-HH Bucharest (Romania). With its 6 High Purity Planar Germanium detectors, GRAPhEME, installed at the EC-JRC GELINA facility, was optimized for measurements of accurate (n,xn $\gamma$) cross sections on actinides. The experimental methodology is based on prompt $\gamma$-ray spectroscopy coupled to time of flight measurements. In a first configuration, involving 4 HPGe, several measurement campaigns have produced numerous sets of data for $^{235}$U [1], $^{238}$U [2] , $^{232}$Th [3] and $^{183,182,184,186,nat}$W isotopes [4]. An update of the setup in 2016, with a segmented (6x6 pixels) HPGe has opened the way for measurements with very active targets. A first campaign on $^{233}$U has been performed and a second one, on $^{239}$Pu is planned in the coming months. Beyond the experimental work, a strong collaboration with theoreticians has emerged allowing the use of the data produced with GRAPhEME to test and constraint nuclear reaction codes [5] like TALYS, CoH and EMPIRE.
In this paper, we would like to present an overview of fifteen years of experiments with GRAPhEME and to highlight the performances and achievements done at EC-JRC GELINA facility. The limitations of our apparatus and methodology will be also described with the solutions we implement continuously to improve GRAPhEME and the associated data analysis methodology. The next challenge tackled with GRAPhEME is to perform (n,2n) and (n,3n) cross sections measurements at the new GANIL/SPIRAL2/NFS facility in Caen, France. A status of this new project will be discussed. This overview paper, if accepted, will be completed by five other submitted papers, which will present more focused items related to GRAPhEME (new inelastic cross section data on $^{233}$U and $^{183}$W, improvement of data analysis methodology, inferring total cross section from measured partial ones, problematic of nuclear structure uncertainties, evaluation).
- On the need for precise nuclear structure data for high quality (n, n'$\gamma$) cross section measurements. G.Henning et al.
- (poster) Using Monte-Carlo method to analyze experimental data and produce uncertainties and covariances. G.Henning et al.
- Experimental measurement of $^{183}$W(n, n'$\gamma$) and (n, 2n$\gamma$) cross sections (preliminary). G.Henning et al.
- Measurement and evaluation of partial and total (n,xn) reaction cross-sections on highly radioactive nuclei of interest for energy production application. F. Claeys et al.
- (poster) From $^{232}$Th(n,n' $\gamma$) cross sections to level production and total inelastic scattering cross section. N. Dari Bako et al.
[1] M.Kerveno et al., Physical Review C 87, 24609 (2013)
[2] M.Kerveno et al., Physical Review C, accepted for publication (2021)
[3] E. Party, Thesis University of Strasbourg, paper in preparation
[4] G. Henning et al., Proceedings of PHYSOR 2020 conference: https://hal.archives-ouvertes.fr/hal-02956052
[5] M.Kerveno et al., Eur. Phys. J Web of Conferences 239, 01023 (2020)
