D. Cester

The light output and the detection efficiency of the liquid scintillator EJ-309

The light output response and the neutron and gamma-ray detection efficiency are determined for liquid scintillator EJ-309. The light output function is compared to those of previous studies. Experimental efficiency results are compared to predictions from GEANT4, MCNPX and PENELOPE Monte Carlo simulations. The differences associated with the use of different light output functions are discussed.

Detecting fast and thermal neutrons with a boron loaded liquid scintillator, EJ-339A.

A commercial boron-loaded liquid scintillator EJ-339 A was studied, using a (252)Cf source with/without polyethylene moderator, to examine the possibility of discriminating slow-neutron induced events in (10)B from fast-neutron events, resulting from proton recoils, and gamma-ray events. Despite the strong light quenching associated with neutron induced events in (10)B, correct classification of these events is shown to be possible with the aid of digital signal processing.

Characterization of a Large Area ZnS(Ag) Detector for Gross Alpha and Beta Activity Measurements in Tap Water Plants

In this work we present the characterization of a large area 200 mm ×200 mm EJ-444 scintillation detector to be used for monitoring gross alpha and beta activity in tap water plants. Specific tests were performed in order to determine the best setup to read-out the light from the detector side. The possibility to stack many detectors and get a compact device with total active area of the order of 1 m2 has been explored. Alpha/beta discrimination, efficiency and homogeneity tests were carried out with alpha and beta sources. Background from ambient radioactivity was measured as well. Alpha/beta real-time monitoring in drinking water is a goal of the EU project TAWARA_RTM.

Characterization and calibration of a novel detection system for real time monitoring of radioactive contamination in water processed at water treatment facilities

Characterization and calibration measurements were carried out at the National Institute of Ionizing Radiation Metrology of ENEA on the TAp WAter RAdioactivity (TAWARA) Real Time Monitor system recently developed for real time monitoring of radioactive contamination in water processed at water treatment facilities. Reference radiations and radionuclides were chosen in order to reflect energy ranges and radiation types of the major water radioactive contaminants possibly arising from environmental, industrial or terroristic origin. The following instrument parameters were tested: sensitivity, selectivity, background, short/long term stability, linearity with respect to activity.

Commissioning and Field Tests of a Van-Mounted System for the Detection of Radioactive Sources and Special Nuclear Material

MODES_SNM project aimed at developing a mobile/portable modular detection system for radioactive sources and Special Nuclear Material (SNM). Its main goal was to deliver a tested prototype capable of passively detecting weak or shielded radioactive sources with accuracy higher than that of currently available systems. By the end of the project all the objectives have been successfully achieved. Results from the laboratory commissioning and the field tests are presented in this publication.

Gamma spectrometer based on CeBr 3 scintillator with compton suppression for identification of trace activities in water

The performance of a spectrometry system (SPEC) for identification of trace activities in water is presented. The SPEC detector is a part of the TAWARA_RTM platform designed for monitoring of water processed for distribution by the Waterworks Company. The SPEC system is dedicated for identification of radioisotopes emitting γ-rays of energies between 50 keV and 2 MeV. The SPEC detector comprises a CeBr3 scintillator grown from specially purified raw material with reduced content of actinides that produce unwanted alpha particle background. In order to reduce the Compton scattering background, an active anti-Compton shield (ACS) made of BGO is used. In addition, a passive lead shield around the ACS is used for further suppression of the external background. The SPEC detector is designed for use with a dedicated concentrator system, that will be used for absorption of a selected group of radioactive elements that may be present in water processed at the waterworks. The system is tested upon capability to detect the γ-ray emitters with activity according to the guidance levels published by the EU in the Council Directive.

Special nuclear material detection studies with the SMANDRA mobile system

The detection of special nuclear material has been studied with the SMANDRA mobile inspection system used both as a high sensitivity passive neutron/gamma spectroscopic tool and as an active inspection device using tagged neutrons. The detection of plutonium samples is possible with passive interrogation, the passive detection of uranium being much more difficult because of the low neutron yield and of the easiness of shielding the gamma rays. However, we show that active interrogation with tagged neutrons is able to provide signatures for the discrimination of uranium against other materials.

An integrated mobile system for port security

An integrated mobile system for port security is presented. The system is designed to perform active investigations, by using the tagged neutron inspection technique, of suspect dangerous materials as well as passive measurements of neutrons and gamma rays to search and identify radioactive and special nuclear materials.