The MOBISIC project, funded by the System@tic Paris-Region cluster, is being developed in the context of local crisis (attack bombing in urban environment, in confined space such as an underground train tunnel etc.) or specific event securing (soccer world cup, political meeting etc.). It consists in conceiving, developing and experimenting a mobile, modular ('plug and play') and multi-sensors securing system. In this project, CEA LIST has suggested different solutions for nuclear risks detection and identification. It results in embedding a CZT sensor and a gamma camera in an indoor drone. This article first presents the different modifications carried out on the UAV and different sensors, and focuses then on the experimental performances.

To monitor radioactivity passing through a vehicle such as a pedestrian, a car, a train or a truck, Radiation Portal Monitors (RMP) are commonly employed. These detection systems consist of a large volume detector set close to the potential source path. An alarm is then triggered when the signal rises over a threshold initially estimated in view of the natural background signal. The approach developed in this work makes use of several detectors in a network along the source path. The correlation detection approach is elaborated to take into account the temporal periodicity of the signals taken by all distributed sensors as a whole. This new detection method is then not based only on counting statistics but also on the temporal series analysis. Therefore, a specific algorithm has been developed in our laboratory for this security application and shows a significant improvement, especially in terms of detection probability increase and false alarm reduction. This paper presents the theoretical approach and promising results obtained by simulation.

Illegal radioactive material transportation detection, by terrorist for example, is problematic in urban public transportation. Academics and industrials systems include Radiation Portal Monitor (RPM) to detect radioactive matters transported in vehicles or carried by pedestrians. However, today's RPMs are not able to efficiently detect a radioactive material in movement. Due to count statistic and gamma background, false alarms may be triggered or at the contrary a radioactive material not detected. The statistical false alarm rate has to be as low as possible in order to limit useless intervention especially in urban mass transportation. The real-time approach depicted in this paper consists in using a time correlated detection technique in association with a sensor network. It is based on several low-cost and large area plastic scintillators and a digital signal processing designed for signal reconstruction from the sensor network. The number of sensors used in the network can be adapted to fit with applications requirements or cost. The reconstructed signal is improved by comparing other approaches. This allows us to increase the device speed that has to be scanned while decreasing the risk of false alarm.In the framework of a project called SECUR-ED Secured Urban Transportation -European Demonstration, this prototype system will be used during an experiment in the Milan urban mass transportation.

This paper deals with a new generation of acquisition systems for nuclear instrumentation. This project, called PING aims at developing instrumentation devices in order to cover a wide range of nuclear measurements with single hardware architecture. More specifically, this device is well suited for neutron measurements. This system is based on a full digital signal processing free from any analog signal neither formatting nor processing. Digitized signals can then be processed for physical information extraction. The dedicated embedded signal processing software in Field Programmable Gate Array (FPGA) allows us to achieve versatile passive or active neutron measurements, or gamma spectrometry. First experimental results are reported in this article. Both gamma and neutron measurements performance are presented.

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The purpose of the FP7 UNCOSS project (Underwater Coastal Sea Surveyor, http://www.uncossproject.org) is to develop a neutron-based underwater explosive sensor to detect unexploded ordnance lying on the sea bottom. The Associated Particle Technique is used to focus the inspection on a suspicious object located by optical and electromagnetic sensors and to determine if there is an explosive charge inside. This paper presents the data acquisition electronics and data analysis software which have been developed for this project. The electronics digitize and process the signal in real-time based on a field programmable gate array structure to perform precise timeof-flight and gamma-ray energy measurements. UNCOSS software offers the basic tools to analyze the time-of-flight and energy spectra of the interrogated object. It allows to unfold the gamma-ray spectrum into pure elemental count proportions, mainly C, N, O, Fe, Al, Si, and Ca. The C, N, and O count fractions are converted into chemical proportions by taking into account the gamma-ray production cross sections, as well as neutron and photon attenuation in the different shields between the ROV (Remotely Operated Vehicle) and the explosive, such as the explosive iron shell, seawater, and ROV envelop. These chemical ratios are plotted in a two-dimensional (2D) barycentic representation to position the measured point with respect to common explosives. The systematic uncertainty due to the above attenuation effects and counting statistical fluctuations are combined with a Monte Carlo method to provide a 3D uncertainty area in a barycentric plot, which allows to determine the most probable detected materials in view to make a decision about the presence of explosive. Index Terms-Associated particle technique, fast neutron interrogation, underwater explosive detection, data acquisition electronics, data analysis.

Homeland security requests the use Radiation Portal Monitor (RPM) to detect and differentiate gamma and neutron radiation. Gamma detection is required for illicit transportation of radioactive matter detection. Neutron detection is important to control nonproliferation of enriched material. Manufacturers worldwide propose sensors based on 3 He which give the actual state of art in term of neutron detection. The price fluctuations due to the announcement of the shortage of 3 He forces manufacturers to find viable alternative. From 10 years sensors providers have the challenge to replace previous 3 He detectors that are known to be the most commonly deployed neutron sensor. As 3 He detectors can only detect neutron, they must be completed with gamma detector. The proposed approach is based on pulse time correlation between adjacent sensors from signal collected by EJ200 plastic scintillators to detect gamma and neutron. Results obtained during FP7 Scintilla project test campaigns show the system relevance for replacement of today's 3 He detectors.

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