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The only method for assessing the fusion power throughput of a deuterium–tritium (DT) reactor presently relies on determining the absolute number of 14 MeV neutrons produced in the DT plasma. An independent method, developed and investigated during the recent DT campaign at the Joint European Torus, is based on the absolute counting of 17 MeV gamma rays produced by the competing T(D, γ)5He reaction that features a very weak branching ratio (about 3–6 × 10−6) when compared to the main T(D, n)4He reaction. The state-of-the-art spectrometer used for gamma-ray measurements in magnetic confinement fusion plasmas is LaBr3(Ce) scintillator detectors, although they require significant neutron shielding to extract a relatively weak gamma-ray signal from a much more abundant neutron field. A better approach relies on a gamma-ray detector that is intrinsically insensitive to neutrons. We have advanced the design of a gamma-ray counter based on the Cherenkov effect for gamma-rays whose energy exceeds 11 MeV, optimized to work in the neutron-rich environment of a steady-state, magnetically confined fusion plasma device. The gamma-rays interact with an aluminum window and extract electrons that move into the radiator emitting photons via the Cherenkov effect. Since the Cherenkov light consists of few photons (25 on average) in the far UV band (100–200 nm), a pre-amplifier is required to transport the photons to the neutron-shielded location, which may be a few meters away, where the readout elements of the detector, either a silicon or standard photomultiplier tube, are placed. The present work focuses on the development of a scintillating GEM (Gas Electron Multiplier) based pre-amplifier that acts as a Cherenkov photon pre-amplifier and wavelength shifter. This paper presents the result of a set of Garfield++ simulations developed to find the optimal GEM working parameters. A photon gain of 100 is obtained by biasing a single GEM foil to 1 kV.

Runaway electron gamma-ray detection system, a novel hard x-ray (HXR) spectrometer optimized for bremsstrahlung radiation measurement from runaway electrons in fusion plasmas, has been developed. The detector is based on a 1‘×1’ LaBr3:Ce scintillator crystal coupled with a photomultiplier tube. The system has an energy dynamic range exceeding 20 MeV with an energy resolution of 3% at 661.7 keV. The detector gain is stable even under severe loads, with a gain shift that stays below 3% at HXR counting rates in excess of 1 MCps. The performance of the system enables unprecedented studies of the time-dependent runaway electron energy distribution function, as shown in recent runaway electron physics experiments at the ASDEX Upgrade and COMPASS tokamaks.

As of today, the standard method employed in tokamaks for the absolute measurement of the neutron flux (thus of the nuclear fusion power) is based on activation foils, being the most robust and unbiased technique for the absolute determination of neutron fluence. However, this technique is not able to provide real-time data useful for the control of future fusion plants like DEMO. In this paper, we present some preliminary results about the R&D activity aimed at developing the Single-crystal Diamond Detectors (SDD) used for fast neutron measurements into an absolute neutron flux monitor. Tests have been conducted at the new NILE neutron source of the Rutherford-Appleton Laboratory, a facility with compact neutron generators with a maximum yield of 109 n/s and 1010 n/s for 2.5 MeV and 14 MeV neutrons, respectively. A series of neutron spectra and flux measurements have been taken with different SDD and associated DAQ. Comparisons with standard activation foils (and namely Fe, Zr, Al and Nb foils for 14 MeV neutrons and In for 2.5 MeV neutrons) and with other reference detectors are presented and discussed. Also discussed is the stability of the SDD over time when employed at high neutron rates in realistic neutron environment, and the effects of neutron irradiation on both the counting rate and detector resolution.

A single gamma-ray spectrometer installed at the end of a collimator can be used to infer the total emission from a tokamak plasma if the transport of gamma-rays from the plasma to the detector is known. In such analysis, the plasma emission profile plays a fundamental role, since it impacts the fraction of plasma volume intercepted by the detector line of sight. In this work, the DT 17 MeV fusion gamma-rays emission profile of the JET discharge #99608 from second 46 to 48 has been estimated both with the TRANSP code and reconstructed through tomographic inversion based on the neutron camera data, assuming that fusion gamma-rays have the same profile as the 14 MeV fusion neutrons. The gamma-ray transport has been evaluated both by MonteCarlo simulations and analytical calculations. By combining MonteCarlo and analytical evaluations of the gamma-ray transport in different ways with the estimated radiation emission profile, we provide four different routes to determine the total gamma-ray yield from measurements whose results agree within better than 10%.

The gas recycle is nowadays an important issue for gaseous detectors operation under study and for this reason, scientists are testing new gas systems for GEM detectors. Since some gas purifier does not allow to use oxygen, the standard Ar-CO2 (70%–30%) cannot be used; thus, new gas mixtures are under investigation. This paper presents the study of a triple GEM detector filled with new gas mixture based on Argon and Nitrogen (Ar-N2) at different concentrations: 90%–10%, 80%–20% and 70%–30%. The GEM detector characterisation has provided the High Voltage working point for the gas mixtures and a comparison between the Ar-CO2 and the Ar-N2.

In fusion plasma scenario, soft X-rays are important tools to study impurities inside plasma. However state-of-the-art silicon detectors cannot survive for long time to the heavy damages due to harsh conditions in tokamaks. GEM detectors are a good alternative thanks to their resilience to radiation damage. In this paper, a GEM detector coupled with new dedicated electronic readout based on GEMINI chip is described. In particular, the detector response has been studied comparing the well established PH method and the ToT method implemented in GEMINI. The results indicate the possibility of using this electronic readout to do soft X-ray spectroscopy measurements in the energy range up to about 10–20 keV.

Dedicated nuclear diagnostics have been designed, developed, and built within EUROFUSION enhancement programs in the last ten years for installation at the Joint European Torus and capable of operation in high power Deuterium–Tritium (DT) plasmas. The recent DT Experiment campaign, called DTE2, has been successfully carried out in the second half of 2021 and provides a unique opportunity to evaluate the performance of the new nuclear diagnostics and for an understanding of their behavior in the record high 14 MeV neutron yields (up to 4.7 × 1018 n/s) and total number of neutrons (up to 2 × 1019 n) achieved on a tokamak. In this work, we will focus on the 14 MeV high resolution neutron spectrometers based on artificial diamonds which, for the first time, have extensively been used to measure 14 MeV DT neutron spectra with unprecedented energy resolution (Full Width at Half Maximum of ≈1% at 14 MeV). The work will describe their long-term stability and operation over the DTE2 campaign as well as their performance as neutron spectrometers in terms of achieved energy resolution and high rate capability. This important experience will be used to outline the concept of a spectroscopic neutron camera for the SPARC tokamak. The proposed neutron camera will be the first one to feature the dual capability to measure (i) the 2.5 and 14 MeV neutron emissivity profile via the conventional neutron detectors based on liquid or plastics scintillators and (ii) the 14 MeV neutron spectral emission via the use of high-resolution diamond-based spectrometers. The new opportunities opened by the spectroscopic neutron camera to measure plasma parameters will be discussed.

The most performant deuterium–tritium (DT) plasma discharges realized by the Joint European Torus (JET) tokamak in the recent DT campaign have produced neutron yields on the order of 1018 n/s. At such high neutron yields, gamma-ray spectroscopy measurements with scintillators are challenging as events from the neutron-induced background often dominate over the signal, leading to a significant fraction of pileup events and instability of the photodetector gain along with the consequent degradation of the reconstructed spectrum. Here, we describe the solutions adopted for the tangential lanthanum bromide spectrometer installed at JET. A data acquisition system with free streaming mode digitization capabilities for the entire duration of the discharge has been used to solve dead-time related issues and a data reconstruction code with pileup recovery and photodetector gain drift restoration has been implemented for off-line analysis of the data. This work focuses on the acquired data storage and parsing, with a detailed explanation of the pileup recovery and gain drift restoration algorithms.

The Joint European Torus (JET) gamma-ray camera has been recently upgraded with the installation of new gamma-ray detectors, based on LaBr

A new position-sensitive thermal neutron detector based on boron-coated converters has been developed as an alternative to today’s standard $$^3\mathrm{He}$$ 3 He -based technology for application to thermal neutron scattering. The key elements of the development are the boron-coated GEM foils (Sauli in Nucl Instrum Methods Phys Res Sect A Accel Spectrom Detect Assoc Equip 386:531, 1997) that are used as a multi-layer neutron converter via the $$^{10}\mathrm{B}(n,\alpha )^7\mathrm{Li}$$ 10 B ( n , α ) 7 Li reaction together with an efficient collection of the produced secondary electrons. This paper reports the test performed on a 3 layers converter prototype coupled to a GEMPix detector (Murtas in Radiat Meas 138:106421, 2020), carried out in order to study the possibility to produce a large-scale multi-layer neutron detector capable to reach high detection efficiency with high spatial resolution and able to sustain the high neutron flux expected in the new neutron spallation source under development like the ESS.

The PRIMA project aims at the construction of two ITER-NBI facilities in Padova (Italy). The first one is called SPIDER which is negative H/D 100 keV RF source, while the second one (MITICA) will be a full scale 1 MeV deuterium beam injector as the one that will be used in ITER. In order to resolve the horizontal beam intensity profile in MITICA and one of the eight beamlets groups in SPIDER, the Close-contact Neutron Emission Surface Mapping (CNESM) system is being developed. The goal of this device is to reconstruct the D− beam evaluating the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. For this reason, the CNESM diagnostic, which is based on nGEM detectors for fast neutrons, will be placed right behind the SPIDER and MITICA beam dump, i.e. in an UHV (Ultra High Vacuum) environment. Since the nGEM detectors need to operate at atmospheric pressure a vacuum sealed detector box has been designed to be installed inside the vacuum vessel and able to sustain atmospheric pressure inside. This paper describes the status of the CNESM diagnostic and underlines the different phases followed during the realization and installation of the diagnostic on the SPIDER beam dump as well as its imaging performances.

The Chiaravalle Cross, a masterpiece of Mediaeval goldsmithery, went under restoration in 2016. This was a unique opportunity to undertake an in-depth multidisciplinary study. Several issues were addressed, as for example the chronology of the Cross, lacking any official document about it. The scientific investigations included in situ and laboratory measurements, and the analyses, part of a multidisciplinary protocol, completely characterized the gemstones adorning the Cross, the cameos, the gold, silver, jasper and glass parts, to derive indications on their provenance, authenticity and dating issues. All the results were shared with the whole collaboration of experts, which included art historians, a restorer, a conservator, a scholar in ancient glyptic, gemologists, archaeometallurgists, physicists and scientists in a very fruitful exchange of knowledge. This work is an example of a real multidisciplinary research, gathering good practices in the study of a complex piece of art.

A state-of-the-art EJ276 plastic scintillator-based detector for neutron spectroscopy has undergone detailed characterization both in a controlled laboratory and on-site at the SPIDER negative ion source facility in Padua. The device will be used for the spectroscopy of 2.5 MeV neutrons produced from Deuterium-Deuterium fusion reactions occurring inside the SPIDER beam dump. A plastic based scintillator with neutron/gamma discrimination has some key advantages over the commonly used organic liquid scintillators with regards economic cost and handling safety. The purpose of this characterization is to determine the operational functionality and reliability of this new breed of detector material. Several tests were performed to verify expected operation with regards to signal reproducibility, long-term stability, and pulse shape discrimination (PSD) capabilities. It was found that the detector system (EJ276 scintillator + photomultiplier tube) performed well in terms of reproducibility and PSD, however the long-term stability of the scintillator light output was seen to diminish considerably over time (>50% decrease) and must be consistently monitored in order to have an accurate conversion scale needed for energy spectroscopy.

The High Voltage Padova Test Facilities (HVPTF) is a R&D project focused on understanding the physical processes behind breakdown and micro-discharges in high-voltage insulation, as well as developing new diagnostics, models, and operational modes to address these challenges and aid in the stable operation of MITICA. The X-rays produced during breakdown have a spectrum that extends from low energy (keV) up to several hundreds of keV and a flux that can reach 106 photons/cm2s. This paper shows the development and preliminary results of a newly designed X-Ray diagnostic based on Gas Electron Multiplier (SXR-GEM). This detector is able to stand very high rate (> MHz) in single photon counting mode and can cover the energy range from 3-50 keV. The XR-GEM detector is equipped with anodic pads (256 pads 6x6 mm2) readout with a new data acquisition system called GEMINI, which gives the possibility to obtain a counting rate of several MHz and sub-ms time resolution together with mm spatial resolution. Preliminary measurement shows that this kind of diagnostic is able to reconstruct the time evolution of the discharge at very high rates and to provide X-rays imaging.

Neutron spallation sources always require new instrument upgrades and innovations in order to improve the quality of their experiments. In this framework, the capability to accurately measure total neutron cross sections at the VESUVIO instrument at the ISIS Facility can be boosted by a tailored transmission detector. For this reason, the first double ceramic thick GEM detector has been realised. Detectors based on GEM technology are broadly developed thanks to their characteristics, such as good spatial resolution (< 0.5 mm), good detection efficiency, high rate capability (MHz/mm2) and a possible coverage area of some meters at low costs. This article shows the realisation of a GEM detector made of a 10B4C cathode, two ceramic thick GEM foils and a padded anode, as well as the device characterisation on the VESUVIO beam line, where stability, γ-sensitivity, imaging capability and sample analysis have been studied. The successful results confirm that the ceramic thick GEM detector performs well in thermal and epithermal neutron detection and it will allow the scientific user community of the instrument to perform better quality transmission measurements so as to determine more accurate total neutron cross section of condensed-matter systems.

The Joint European Torus (JET) gamma-ray camera has been recently upgraded with the installation of new gamma-ray detectors, based on LaBr3(Ce) scintillation crystals, which add spectroscopic capability to the existing system allowing measurements with good energy resolution (5% at 0.622 MeV), a dynamic range from hundreds of keV up to about 30 MeV, and high counting rate capabilities of MCps. First gamma-ray measurements during the C38 campaign of the JET have been successfully carried out, in particular, in D-3He plasmas from three-ion ion cyclotron resonance heating experiments, where the detection of 16.4 MeV γ-rays from D + 3He → γ + 5Li reactions with the gamma-ray camera upgrade allowed determining the spatial profile of alpha particles born in D + 3He fusion reactions.

An important instrumental development work has been done in the last two decades in the field of neutron and gamma ray spectroscopic measurements of magnetic confinement plasmas. Starting from the present state of the art instrumentation installed at JET, this paper reviews the recent development that has been carried out within the EUROFUSION programme for the forthcoming high power JET D and DT campaign. This development was dedicated to the realization of new compact neutron and gamma-ray spectrometers which combine very high energy resolution (typically better than 5%) and MHz counting rate capabilities allowing for time resolution in the 10 ms time scale. One of the advantages offered by the compact dimensions of these spectrometers is to make possible their use in multiple sight-line camera configurations, such as for future burning plasma reactors (ITER and DEMO). New compact neutron spectrometers based on single crystal diamond detectors have been developed and installed at JET for measurements of the 14 MeV neutron spectrum. Measurements on a portable DT neutron generator have shown that neutron spectroscopy of the accelerated beam ions at unprecedented energy resolution (∼1% at 14 MeV) is possible, which opens up new opportunities for diagnosing DT plasmas. For what concerns gamma ray measurements, the JET gamma ray camera has been recently upgraded with new compact spectrometers based on a LaBr3 scintillator coupled to Silicon Photomultiplier with the dual aim to improve the spectroscopic and rate capabilities of the detectors. The upgrade camera system will reconstruct the spatial gamma ray emissivity from the plasma in the MeV energy range at MHz counting rates and energy resolution in the 2-4% range. This will allow physics studies of gamma rays produced by the interaction of fast ions with impurities in the plasma and bremsstrahlung emission from runaway electrons.

Silicon Carbide (SiC) is a relatively new entry in the world of solid-state detectors. Although SiC response to neutrons is more complex than the one obtained with diamonds, the measured energy resolution (FWHM/ E d 4 % ) makes SiC an interesting alternative to diamond and silicon detectors for fast neutrons. The results obtained from the measurements of the response of a 100 μ m thick SiC detector to neutrons in the energy range between 3 and 20 MeV at the n_TOF spallation source at CERN are presented in this paper. By selecting the neutron energy by means of the time of flight, the detector response to quasi-mono-energetic neutrons was measured. The main neutron-induced nuclear reactions were identified in the measured pulse height spectrum. Detection efficiency as a function of neutron energy was measured and interpreted based on available neutron cross section and by making use of Monte Carlo simulations.

One of the main configuration of Fast Ion Loss Detectors (FILD) installed in present day tokamaks and stellarators consists of a collimator and a scintillator coupled to a suitable optical system. In view of their use at the JT-60SA and ITER tokamaks, the impact of the background radiation induced by fusion born neutrons on the instrument must be quantified. In JT-60SA the interaction is predominantly due to 2.5 MeV neutrons born from D –D reactions while, at ITER, 14 MeV neutrons born from D –T are of additional concern, as their flux is expected to be the same as the one from the escaping ions at the position of the FILD. In particular, the generation of background charged particles when neutrons interact with the FILD supporting structure is of most relevance, both at JT-60SA and ITER. In this work we present the results of a study on the neutron sensitivity of the whole FILD setup to 2.5 MeV and 14 MeV neutrons. A set of GEANT4 simulations with a detector geometry derived from the current CAD model of the proposed FILD design has been carried out. Modelling has been validated at the Frascati Neutron Generator, where aspects of the interaction of MeV range neutrons with the FILD setup have been tested. Based on our simulations, we predict that neutrons will induce a measurable background on the FILD, both at JT-60SA and ITER, but they will also not impede measurements.

The experimental thermal neutron cross sections of the 20 proteinogenic amino acids have been measured over the incident-neutron energy range spanning from 1 meV to 10 keV and data have been interpreted using the multi-phonon expansion based on first-principles calculations. The scattering cross section, dominated by the incoherent inelastic contribution from the hydrogen atoms, can be rationalised in terms of the average contributions of different functional groups, thus neglecting their correlation. These results can be used for modelling the total neutron cross sections of complex organic systems like proteins, muscles, or human tissues from a limited number of starting input functions. This simplification is of crucial importance for fine-tuning of transport simulations used in medical applications, including boron neutron capture therapy as well as secondary neutrons-emission induced during proton therapy. Moreover, the parametrized neutron cross sections allow a better treatment of neutron scattering experiments, providing detailed sample self-attenuation corrections for a variety of biological and soft-matter systems.

The ITER project requires additional heating by two neutral beam injectors, each accelerating up to 1 MV a 40 A beam of negative deuterium ions for one hour. Such requirements have never been reached, so it was decided to build in Padova a facility (PRIMA) that hosts two experimental devices: SPIDER, a 100 kV negative H/D RF beam source, and MITICA, a full-scale injector for the ITER NBI. SPIDER has begun operation in 2018, while MITICA is expected to start after 2020. In both devices the accelerated deuterium beam impinges on an actively cooled beam dump used to stop the deuterons. Detection of fusion neutrons produced between beam–deuterons and dump-embedded deuterons will be used as a means to resolve the horizontal beam intensity profile. A neutron detection system called Close-contact Neutron Emission Surface Mapping (CNESM) is installed right behind the SPIDER beam dump, with the aim to provide the neutron emission map of the beam dump surface. The core of this diagnostic system is an nGEM (neutron-Gas Electron Multiplier) detector which will be able to reconstruct the fast neutron beam profile with an efficiency of about 10−4. A crucial point in order to correctly reconstruct the profile of the deposited D − power is the directionality discrimination capability of the detector. This paper reports on the results of the characterization of the nGEM directionality capabilities, performed at the Frascati Neutron Generator (FNG) using 2.5 MeV neutrons, before installation of the detector inside the SPIDER vacuum vessel.

In this work we present the response of a new large volume 4H Silicon Carbide (SiC) detector to 14 MeV neutrons. The device has an active thickness of 100 μ m (obtained by epitaxial growing) and an active area of 25 mm2. Tests were conducted at the ENEA-Frascati Neutron Generator facility by using 14.1 MeV neutrons. The SiC detector performance was compared to that of Single-Crystal Diamond (SCD) detectors. The SiC response function was successfully measured and revealed a very complex structure due to the presence in the detector of both Silicon and Carbon atoms. Nevertheless, the flexibility in the SiC manufacturing and the new achievements in terms of relatively large areas (up 1x1 cm2) and a wide range of thicknesses makes them an interesting alternative to diamond detectors in environments where limited space and high neutron fluxes are an issue, i.e. modern neutron cameras or in-vessel tokamak measurements for the new generation fusion machines such as ITER. The absence of instabilities during neutron irradiation and the capability to withstand high neutron fluences and to follow the neutron yield suggest a straightforward use of these detectors as a neutron diagnostics.

At the present time, different kinds of thermal neutron detectors are under development at the European Spallation Source research facility, in order to overcome the well-known problem of the He-3 shortage. One of these new systems relies on the use of a 3D neutron convener cathode that consists of a stack of aluminum grids, covered by a 0.9 mu m B-10 enriched boron carbide layer ((B4C)-B-10). As the conversion efficiency is a function of the boron thickness and the mean free path of the charged particles produced in the neutron induced reaction, the characterization of the boron carbide layer uniformity over the grids becomes crucial. In this work, a non-destructive method to map the thickness distribution of the converter layer over the grids is shown. The measurements exploit the white-beam neutron radiography technique where the specimen is irradiated at different angles. This experiment has been performed at the IMAT beamline operating at the ISIS spallation neutron source (UK). The results confirm that this non-destructive, wide-ranging technique allows a reliable and fast sample characterization and that it may be exploited in similar analyses where equivalent requirements are requested.

Diagnosing soft x-ray (SXR) emission from tokamaks represents a unique source of information, since it allows the study of several plasma parameters, such as the electron and ion temperature, the investigation of the ionization equilibrium, particle and impurities transport and the study of MHD fluctuations and disruptions. A new SXR diagnostic system called EXODUS (Enhanced X-ray Optimized Detector for Use in multiple Scenarios) is under development with the aim to obtain energy resolved SXR emission profiles from the plasma with a high time resolution (

The ITER neutral beam test facility under construction in Padova will host two experimental devices: SPIDER, a 100 kV negative H/D RF beam source, and MITICA, a full scale, 1 MeV deuterium beam injector . SPIDER will start operations in 2016 while MITICA is expected to start during 2019. Both devices feature a beam dump used to stop the produced deuteron beam. Detection of fusion neutrons produced between beam-deuterons and dump-implanted deuterons will be used as a means to resolve the horizontal beam intensity profile. The neutron detection system will be placed right behind the beam dump, as close to the neutron emitting surface as possible thus providing the map of the neutron emission on the beam dump surface. The system uses nGEM neutron detectors . These are Gas Electron Multiplier detectors equipped with a cathode that also serves as neutron–proton converter foil. The cathode is designed to ensure that most of the detected neutrons at a point of the nGEM surface are emitted from the corresponding beamlet footprint (with dimensions of about 40×22 mm2) on the dump front surface. The size of the nGEM detector for SPIDER is 352 mm×200 mm. Several smaller size prototypes have been successfully made in the last years and the experience gained on these detectors has led to the production of the full size detector for SPIDER during 2014. This nGEM has a read-out board made of 256 pads (arranged in a 16×16 matrix) each with a dimension of 22 mm×13 mm. This paper describes the production of this detector and its tests (in terms of beam profile reconstruction capability, uniformity over the active area, gamma rejection capability and time stability) performed on the ROTAX beam-line at the ISIS spallation source (Didcot-UK).

Since 2006 lithium as an advanced plasma facing material has been tested on the Frascati Tokamak Upgrade (FTU). Lithium in the liquid phase acts both as plasma facing component, i.e. limiter, and plays also a role in plasma operation because by depositing a lithium film on the walls (lithization) oxygen is gettered. As in all deposition processes, even for the lithization, the presence of impurities in plasma phase strongly affects the properties of the deposited film. During the 2008 campaigns of FTU it was observed a strong release of carbon dioxide (during disruptions), resulting in successive serious difficulty of operation. In order to find the possible reactions occurred, we have analyzed the surface of two tiles of the toroidal limiter close to the Liquid Lithium Limiter (LLL). The presence of molybdenum oxides and carbides suggested that the surface temperatures could have exceeded 1000 K, likely during disruptions. lithium oxides and hydroxides have been found on the tiles and in the dust collected in the vessel, confirming the presence of LiO and LiOH and a not negligible concentration of Li 2 CO 3 especially at the LLL location. On the basis of the above results, we propose here a simple rationale, based on a two reactions mechanism, which can explain the formation of Li 2 CO 3 and its subsequent decomposition during disruption with release of CO 2 in the vessel. Admitting surface temperatures above 1000 K during a disruption, relatively high partial pressures of CO 2 are also predicted by the equilibrium constant for Li 2 CO 3 decomposition.

A set of gamma ray spectrometers has been designed for ITER within the Radial Gamma Ray Spectrometer (RGRS) project. The aim of this project is designing a system, integrated with the ITER radial neutron camera, which is able to measure the gamma-rays emitted from the plasma with a good energy resolution (about 1.5% at 4.44 MeV) and at high counting rates (in excess of 1 MHz). The RGRS will be able to operate both in the D phase and in the full-power DT phase and will measure gamma rays from (i) reactions between fast ions, such as particles, and light impurities and (ii) bremsstrahlung emission generated by runaway electron interactions with both plasma bulk and tokamak walls. The RGRS detectors are arranged in nine lines of sights (able to cover a radial region with r < a/3), each featuring a large LaBr3 scintillator crystal. Due to the high neutron flux and magnetic field, several solutions have been adopted to guarantee a good signal to background ratio and MHz counting rate capabilities. The RGRS is capable to combine space and energy distribution measurements of particles and runaway electrons, which will help the study of the fast particle physics in a burning plasma. Published by AIP Publishing. https://doi.org/10.1063/1.5038963

Building the European Spallation Source (ESS), the most powerful neutron source in the world, requires significant technological advances at most fronts of instrument component design. Detectors are not an exception. The existing implementations at current neutron scattering facilities are at their performance limits and sometimes barely cover the scientific needs. At full operation the ESS will yield unprecedented neutron brilliance. This means that one of the most challenging aspects for the new detector designs is the increased rate capability and in particular the peak instantaneous rate capability, i.e.\,the number of neutrons hitting the detector per channel, pixel or cm$^2$ at the peak of the neutron pulse. This paper focuses on estimating the incident and detection rates that are anticipated for the Small Angle Neutron Scattering (SANS) instruments planned for ESS. Various approaches are applied and the results thereof are presented.

Dust present in the vessel of FTU has been collected and analysed. Being FTU a device with full metal plasma facing components for the whole life and equipped with a liquid lithium limiter (LLL) make FTU of special interest from a point of view of dust studies. Analyses were conducted by standard dust analysis methods and by dedicated analysis, as X-rays and neutron diffraction, to investigate the presence of lithium compounds due the presence of the LLL in FTU. Dust collected near the LLL presents a different elemental composition, namely Li compounds, compared to the dust collected in the rest of the vessel; in particular LiO 2 , LiOH, and Li 2 CO 3 . On the basis of these results, the formation of Li 2 CO 3 is proposed via a two steps process. Results of fuel retention measured by thermal desorption spectroscopy (TDS) method show that fuel retention should not be an issue for FTU.

This work presents the first neutron characterization of artefacts from the grave-goods of Kha and Merit, a unique cultural treasure of mankind and preserved at the Museo Egizio in Turin. This magnificent collection, discovered in the early years of the last century, includes an impressive amount of artefacts such as coffins, textiles, metallic and ceramic pottery, and alabaster containers. The present study investigates two sealed potteries, using enhanced Neutron Tomography, Radiography, and Prompt Gamma Activation Analysis techniques. The neutron probe provides access to the morphological reconstructions of the inner parts of the vases and to map, with unprecedented details, the elemental composition of the surfaces and bulk areas of the potteries. The present work extends the knowledge to hitherto unknown contents of the sealed vases unlocking their secrets.

Neutron Imaging using epithermal neutron beams is a technique that is not yet widely exploited. However, it offers an interesting potential allowing for joining the advantages of imaging (i.e. space-resolved information) along with element sensitivity (at least for most medium-weight elements). In the following pages, the development of Neutron Resonance Transmission Imaging (NRTI) is presented. In recent years it has been developed by two separated groups making use of the characteristics of pulsed sources optimized for Time-of-Flight measurements. An application to a cultural heritage object at the ISIS facility is presented as an example in this chapter.

A neutron diagnostic based on Gas Electron Multiplier is proposed for the MITICA beam injector test facility. The detection system is called Close-contact Neutron Emission Surface Mapping (CNESM) and aims at providing the beam intensity profile on the horizontal direction by measuring the neutron emission from the beam dump surface by placing a detector right behind the dump. CNESM uses Gas Electron Multiplier detectors equipped with a cathode that also serves as neutron-proton converter foil, named nGEM. The cathode, made of a thin polythene film and an aluminium film, is designed for detection of neutrons emitted with and angle between 30 and 70 degrees with respect to the deuterium beam axis. Neutron scattering in the dump and neutron detection with the nGEM were simulated with the MCNP6.1.1 code.

The paper describes a new compact neutron spectrometer optimized for the detection of 2.5 MeV neutrons for fusion plasma applications. The first neutron spectroscopy measurements on a nuclear fusion plasma experiment (EAST) with this detector are also reported together with the data interpretation. The detector allowed separating the different neutron emission components from the plasma and to validate the effectiveness of the Neutral Beam Injection (NBI) heating. A possible improvement of the diagnostic has been also identified in order to increase the detector sensitivity to weak components of the neutron spectrum, such as those due to the Ion Cyclotron Resonace Heating (ICRH). The relatively simple response function of the (CLYC)-L-7 detector to 2.5 MeV neutrons together with its good capability in the n/gamma discrimination, makes this detector an interesting spectrometer for deuterium (D) plasma diagnostics. In particular, its compactness allows for integration in a multi-line of sight camera where space constraints are present.

Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources. © 2016 IOP Publishing Ltd.

Single-crystal Diamond Detectors (SDDs), due to their good charge carrier transport properties, low leakage and therefore good energy resolution, are good candidates for fast neutron measurement on pulsed spallation sources and fusion plasma experiments. Moreover, diamonds are known to be resistant to neutron irradiation. Nevertheless, measurements show transient effects during irradiation with ionizing particles, as the alpha particle calibration sources. The decrease of the detector counting rate of a counting chain and the pulse height are interpreted as due to a charge trapping inside the detector, which modifies the drift electric field. These instabilities are strongly dependent on the specific type of the interaction. Measurements have been carried out with both alpha particles in the laboratory and neutrons at the ISIS neutron spallation source. We show that these polarization effects are not permanent: the detector performances can be restored by simply inverting the detector bias high voltage. Prime Novelty Statement: The measurements described in the paper were performed in order to study the polarization effect in Single-crystal Diamond Detector. This effect was observed under alpha particle and neutron irradiation. With the Transient Current Technique an interpretation of the effect is given. (C) 2015 Elsevier B.V. All rights reserved.

Experiments on runaway electrons have been performed for the determination of the critical electric field for runaways generation. A large database of post-disruption generated runaway beams has been analysed in order to identify linear dynamical models for new position and current runaway beam controllers, and experiments of Electron Cyclotron assisted plasma start-up have shown the presence of runaway electrons also below the expected electric field threshold, indicating that the radio-frequency power acts as seeding for fast electrons. A linear micro-stability analysis of Neon doped pulses has been carried out to investigate the mechanisms leading to the observed density peaking. A study of the ion drift effects on the MARFE instability has been performed and the peaking of density profile in the high density regime has been well reproduced using a thermo-diffusive pinch in the particle transport equation. The analysis of the linear stability of the 2/1 tearing mode observed in high density plasmas has highlighted a destabilization with increasing peaking of the current profile during the density ramp-up, while the final phase of the mode temporal evolution is characterized by limit cycles on the amplitude/frequency plane. A Liquid Lithium Limiter with thermal load capability up to 10 MW/m2 has been tested. The pulse duration has been extended up to 4.5 s and elongated configurations have been obtained for 3.5 s, with the X-point just outside the plasma chamber. W/Fe samples have been exposed in the SOL in order to study the sputtering of Fe and the W enrichment of the surface layer. Dusts have been collected and analyzed, showing that the metallic population exhibits a high fraction of magnetic grains. A new diagnostic for in-flight RE studies has allowed to provide simultaneously the image and the visible/infrared spectrum of the forward and backward radiation. A fast infrared camera for thermo-graphic analysis has provided the pattern of the toroidal limiter heating by disruption heat loads, and a triple-GEM detector has been mounted on one equatorial port and tested for soft-X rays diagnostic. The Collective Thomson Scattering diagnostic has been upgraded and used for investigations on Parametric Decay Instability excitation by Electron Cyclotron beams correlated with magnetic islands, and new capabilities of the Cherenkov probe have been explored in the presence of Beta-induced Alfvén Eigenmodes associated to high-amplitude magnetic islands.

As planned in the previous year, EDDI testing plan started with a round robin test campaign on EUROFER 97. The campaign of TENSILE testing was completed in Oct. 2016, and the data was discussed just after such term. The first real data requests have been presented during 2016, and namely creep tests on pre-fatigued specimens, LCF tests and fracture tests with a non-standard yoke/pin configuration. The real tests required have been prioritized and started in 2016.They will continue in 2017 with other tests (especially LCF) to be distributed to the different RUs following cost exigencies and results of the RR.

The high-energy neutron component (En > 10 MeV) of the neutron spectrum of PRISMA, a beam-line at the ISIS spallation source, has been characterized for the first time. Neutron measurements using a Single-crystal Diamond Detector at a short-pulse source are obtained by a combination of pulse height and time of flight analysis. An XY scan provides a 2D map of the high-energy neutron beam which has a diameter of about 40 mm. The high neutron flux, that has been found to be (3.8 ± 0.7) 105 cm−2s−1 for En > 10 MeV in the centre, opens up for a possible application of the beam-line as a high-energy neutron irradiation position. Results are of interest for the development of the ChipIR beam-line, which will feature an atmospheric-like neutron spectrum for chip irradiation experiment. Furthermore, these results demonstrate that diamond detectors can be used at spallation sources to investigate the transport of high-energy neutrons down instruments which is of interest in general to designers as high-energy neutrons are a source of background in thermal beamlines.

Milan Cathedral is one of the biggest and widest churches ever built among the other coeval architectures. It had a very long and complex construction history, which started in 1386 and lasted more than four centuries. The dominant style is the European gothic but the lombard tradition has strongly influenced the composition. Gothic cathedrals were diffusely built in Europe during the Middle Age, and each region developed its own local interpretation. However, a common feature of the style was the presence of slender pillars and of many elements able to reduce the horizontal thrusts of the vaults, such as spires, buttresesses, flying buttresesses and tie rods. In Milan Cathedral, tie rods have a fundamental role due to the specific characteristics of the structural system and its complex history. In 2012, a broken tie rod was found and it was substituted with a new one. Therefore, a multidisciplinary research on these elements started, aiming at a deeper material characterization and an in-situ identification of local defects. Among non-destructive techniques, several neutron analyses were performed on different samples. We will report on neutron diffraction measurements and neutron resonant capture analysis on part of the original broken tie rod. Moreover, neutron imaging was recorded on other iron tie rods (from an external spire). Results will be useful for an independent assessment and validation of models and of new on-site monitoring techniques, since no other conventional non-destructive technique will allow the same characterization.

An investigation of the gamma background was carried out in the VESUVIO spectrometer at the ISIS spallation neutron source. This study, performed with a yttrium-aluminum-perovskite (YAP) scintillator, follows high resolution pulse height measurements of the gamma background carried out on the same instrument with the use of a high-purity germanium detector. In this experimental work, a mapping of the gamma background was attempted. trying to find the spatial distribution and degree of directionality of the different contributions identified in the previous study. It is found that the gamma background at low times is highly directional and mostly due to the gamma rays generated in the moderator-decoupler system. The other contributions, consistently to the findings of a previous experiment, are identified as a nearly isotropic one due to neutron absorption in the walls of the experimental hall, and a directional one coming from the beam dump. (c) 2009 Elsevier B.V. All rights reserved.

Fast neutron detectors with a sub-centimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. Based on the results obtained with small area prototypes, the first medium-size (20 x 35.2 cm2 active area) nGEM detector has been realized for both the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as a beam monitor for fast neutrons beam lines at spallation sources, too. The nGEM is a Triple GEM gaseous detector equipped with polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the performance of the medium-size nGEM detector tested at the VESUVIO beam line of the ISIS spallation source. Being this detector the actual largest area fast neutron detector based on the GEM technology, particular attention was paid in the study of detector response in different points over the active area. Measurements of GEM counting rate (both as a function of VGEM and of time) and of the capability of the detector to reconstruct the beam in different positions are presented. This detector serves as a basis for the realization of an even larger area detector that will be used in the MITICA NBI prototype for ITER that represents the evolution of SPIDER.

The planned round robin test campaign, started in 2015, will continue in 2016 (with the LCF tests). The first tests will be performed during 2016 on "real" samples (and namely with pre-fatigued creep experiments).

The ITER neutral beam test facility under construction in Padova will host two experimental devices: SPIDER, a 100 kV negative H/D RF source, and MITICA, a full scale, 1MeV deuterium beam injector. A detection system called Close - contact Neutron Emission Surface Mapping (CNESM) is under development with the aim to resolve the horizontal beam intensity profile in MITICA and one of the eight beamlet groups in S PIDER, with a spatial resolution of 3 and 5 cm2 respectively. This is achieved by the evaluation of the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. CNESM uses nGEM detectors, i .e. GEM detectors equipped with a cathode that also serves as neutron - proton converter foil. The diagnostic will be placed right behind the SPIDER and MITICA beam dump, i.e. in an UHV environment, but the nGEM detectors need to operate at atmospheric press ure, so to contain the detector a vacuum sealed box has been designed to be installed inside the vacuum vessel and at atmospheric pressure inside. The box design was driven by the need to minimize the neutron attenuation and the distance between the beam d ump surface and the detector active area. This paper presents the status of the CNSESM diagnostics and describes the design of the detectors and of the sealed box (in particular the analysis carried out to define its parameters, the necessary pumping and l eak test procedures to ensure the compatibility of the box with the UHV environment and the proposed installation/removal procedure ). Also the general layout of the diagnostic as part of the SPIDER experiment will be discussed. Finally the preliminary des ign of MITICA CNESM diagnostic will be introduced. This work was set up in collaboration and financial support of Fusion for Energy.

The Testing Capability Map collected for the different EDDI research units was updated in spring 2015. As planned in the previous year, EDDI testing plan started with a round robin test campaign on EUROFER 97. First tests have started in November 2015 with the round robin tensile campaign. The first "real" test requests have been provided and prioritized at the end of 2015.

Single-crystal Diamond Detectors (SDDs), due to their high radiation hardness, fast response time and small size, are good candidates as fast neutron detectors in those environments where the high neutron flux is an issue, such as spallation neutron sources and the next generation thermonuclear fusion plasmas, i.e. the ITER experiment. Neutron detection in SDDs is based on the collection of electron-hole pairs produced by charged particles generated by neutron interactions with 12C. Recent measurements have demonstrated the SDD capability of measuring the neutron flux with a good energy resolution and at high rates. In this work a novel detector based on a 12-pixels SDD matrix will be presented. Each pixel is equipped with an independent electronic chain: the fast shaping preamplifier coupled to a digitizer is able to combine the high rate capability and the good energy resolution. Two CAEN digitizers are compared and the possibility of performing good energy resolution measurements (< 2%) and at high rates (> 1 MHz per channel) is described. Each pixel was characterized and calibrated using an 241Am source: the energy resolution was evaluated and gives a mean value of 1.73% at 5.5 MeV. The good energy resolution achieved and its uniformity between pixels are the demonstration of the capability of this novel detector as a spectrometer. This system will be installed during the next Deuterium-Tritium campaign on a collimated vertical line of sight at JET for 14MeV neutron measurements.