"The MODES_SNM project aims to carry out technical research in order to develop a prototype for a mobile, modular detection system for radioactive and Special Nuclear Materials (SNM). To maximize the detection capability for SNM the project will develop new detectors for fast and thermal neutrons, as well as gamma-rays, based on the technology of high pressure scintillation cells using noble gases (as 4-He and Xe) recently developed by ARKTIS. The proof-of-principle of the new detectors has already been recently demonstrated. The project’s goal is to deliver a tested prototype of a modular mobile system capable of passively detecting weak or shielded radioactive sources with accuracy higher than that of currently available systems. The identification of the gamma-ray emitter is also possible by using the spectroscopic analysis performed by high pressure Xe cells whereas the ratio between fast and thermal neutrons will bring information about the eventual shielding around the source. The R&D aims at improve the current detectors (i.e. at designing, constructing and testing robust, safe, and lightweight high pressure cells with an advanced read-out system) so that they can be used as basic components of the modular mobile system. A suitable Information System will be also developed to manage the detectors, integrate and analyze the data, and provide to the user simple information derived by a decision tree utilizing the data from the three types of detectors. The prototype detection system is the major deliverable of the project. The project also includes the qualification of this detection system in laboratory condition to quantify its detection performance and ultimate limits, as well as a demonstration phase in which the detection system will be field-tested by the end-user group established within the project."