First steps toward the development of SONATE, a Compact Accelerator driven Neutron Source

Facilities providing bright thermal neutron beams are of primary importance for various research topics such as condensed matter experiments, neutron-imaging or medical applications. Currently these are mainly spallation sources and nuclear reactors. However, these later facilities are ageing and the political context does not favor the building of new ones. This is the case in CEA-Saclay (France), where the Orphee reactor is planned to shutdown in 2019. Therefore, another local facility, affordable by one country, able to provide high brilliance neutron beams has to be built. At CEA-Saclay, a compact accelerator driven neutron source, SONATE, is investigated in taking advantage of the IPHI accelerator able to deliver a 3 MeV proton beam with an intensity up to 100 mA. In the future, SONATE is foreseen to operate with 20 MeV protons to increase the neutron brightness. In addition to the difficulties to operate such high intensity accelerators, the other challenges regard the target-moderator-reflector (TMR) design which is crucial to maximize the neutron flux at the detector location. At CEA-Saclay, several experiments were performed between 2016 and 2019 with the IPHI accelerator. Geant4 simulations were also developed. They demonstrate the feasibility of such concept and enable to find the best TMR configuration for the future SONATE facility. These developments are reported in this article.

A Study of Loop Detectors Based on Vehicular Trajectories

Vehicular trajectories are firstly achieved on the basis of vehicle time and space information obtained from VISSIM simulation. Via simulating setting loop detectors at different locations and collecting traffic data in different time intervals, different traffic flow fundamental diagrams on the basis of the detect data are then generated. Finally, comparing these fundamental diagrams, two conclusions are achieved. The loop detective interval has a significant impact on fundamental diagrams while the detector location has an extremely limited influence. Particularly, fundamental diagram is more aggregated with longer data collecting interval and capacity is more easily to be obtained with longer distance between neighboring loop detectors.