Search

The detection of thermal neutrons is increasingly important for several fields of interest, so new versatile, manageable and adaptable detectors are needed for applications in different environments and situations. To date, scintillators for thermal neutrons available on the market are fragile and with low adaptability. In this work, flexible and robust thermal neutron scintillators with improved properties as compared to commercial ZnS:Ag based phosphors are produced. The scintillators are produced by mixing ZnS:Ag powder and 6LiF nano-crystals in polysiloxane binders. 6LiF nano-crystals are synthesized by co-precipitation method, and the detection efficiency is optimized by tuning the crystal size through different solvent/co-solvent ratios. Then, the detection yield to thermal neutrons is investigated as related both to the crystal size and to the binder. Two different siloxanes, either with pendant phenyl groups or with aliphatic groups are used, the former being intrinsically fluorescent and with higher polarizability than the latter. The response to γ -rays is also evaluated. Lastly, the right combination of base resin and 6LiF crystals size allows to produce flexible scintillators for thermal neutrons with performances comparable to the commercial standard and with higher mechanical robustness and stability.

This paper describes a distributed Data Acquisition System (DAQ) developed for the TAWARA_RTM project (TAp WAter RAdioactivity Real Time Monitor). The aim is detecting the presence of radioactive contaminants in drinking water; in order to prevent deliberate or accidental threats. Employing a set of detectors, it is possible to detect alpha, beta and gamma radiations, from emitters dissolved in water. The Sensor Network (SN) consists of several heterogeneous nodes controlled by a centralized server. The SN cyber-security is guaranteed in order to protect it from external intrusions and malicious acts. The nodes were installed in different locations, along the water treatment processes, in the waterworks plant supplying the aqueduct of Warsaw, Poland. Embedded computers control the simpler nodes, and are directly connected to the SN. Local-PCs (LPCs) control the more complex nodes that consist signal digitizers acquiring data from several detectors. The DAQ in the LPC is split in several processes communicating with sockets in a local sub-network. Each process is dedicated to a very simple task (e.g. data acquisition, data analysis, hydraulics management) in order to have a flexible and fault-tolerant system. The main SN and the local DAQ networks are separated by data routers to ensure the cyber-security.

A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.