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The SoLid experiment aims to measure neutrino oscillation at a baseline of 6.4 m from the BR2 nuclear reactor in Belgium. Anti-neutrinos interact via inverse beta decay (IBD), resulting in a positron and neutron signal that are correlated in time and space. The detector operates in a surface building, with modest shielding, and relies on extremely efficient online rejection of backgrounds in order to identify these interactions. A novel detector design has been developed using 12800 5 cm cubes for high segmentation. Each cube is formed of a sandwich of two scintillators, PVT and 6LiF:ZnS(Ag), allowing the detection and identification of positrons and neutrons respectively. The active volume of the detector is an array of cubes measuring 80× 80× 250 cm (corresponding to a fiducial mass of 1.6 T), which is read out in layers using two dimensional arrays of wavelength shifting fibres and silicon photomultipliers, for a total of 3200 readout channels. Signals are recorded with 14 bit resolution, and at 40 MHz sampling frequency, for a total raw data rate of over 2 Tbit/s. In this paper, we describe a novel readout and trigger system built for the experiment, that satisfies requirements on: compactness, low power, high performance, and very low cost per channel. The system uses a combination of high price-performance FPGAs with a gigabit Ethernet based readout system, and its total power consumption is under 1 kW. The use of zero suppression techniques, combined with pulse shape discrimination trigger algorithms to detect neutrons, results in an online data reduction factor of around 10000. The neutron trigger is combined with a large per-channel history time buffer, allowing for unbiased positron detection. The system was commissioned in late 2017, with successful physics data taking established in early 2018. The SoLid experiment aims to measure neutrino oscillation at a baseline of 6.4 m from the BR2 nuclear reactor in Belgium. Anti-neutrinos interact via inverse beta decay (IBD), resulting in a positron and neutron signal that are correlated in time and space. The detector operates in a surface building, with modest shielding, and relies on extremely efficient online rejection of backgrounds in order to identify these interactions. A novel detector design has been developed using 12800 5 cm cubes for high segmentation. Each cube is formed of a sandwich of two scintillators, PVT and 6LiF:ZnS(Ag), allowing the detection and identification of positrons and neutrons respectively. The active volume of the detector is an array of cubes measuring 80x80x250 cm (corresponding to a fiducial mass of 1.6 T), which is read out in layers using two dimensional arrays of wavelength shifting fibres and silicon photomultipliers, for a total of 3200 readout channels. Signals are recorded with 14 bit resolution, and at 40 MHz sampling frequency, for a total raw data rate of over 2 Tbit/s. In this paper, we describe a novel readout and trigger system built for the experiment, that satisfies requirements on: compactness, low power, high performance, and very low cost per channel. The system uses a combination of high price-performance FPGAs with a gigabit Ethernet based readout system, and its total power consumption is under 1 kW. The use of zero suppression techniques, combined with pulse shape discrimination trigger algorithms to detect neutrons, results in an online data reduction factor of around 10000. The neutron trigger is combined with a large per-channel history time buffer, allowing for unbiased positron detection. The system was commissioned in late 2017, with successful physics data taking established in early 2018.

The SoLid experiment has been designed to search for an oscillation pattern induced by a light sterile neutrino state, utilising the BR2 reactor of SCK$\bullet$CEN, in Belgium. The detector leverages a new hybrid technology, utilising two distinct scintillators in a cubic array, creating a highly segmented detector volume. A combination of 5 cm cubic polyvinyltoluene cells, with $^6$LiF:ZnS(Ag) sheets on two faces of each cube, facilitate reconstruction of the neutrino signals. % The polyvinyltoluene scintillator is used as an $\overline{\nu}_e$ target for the inverse beta decay of ($\overline{\nu}_e + p \rightarrow e^{+}+n$), with the $^6$LiF:ZnS(Ag) sheets used for associated neutron detection. Scintillation signals are read out by a network of wavelength shifting fibres connected to multipixel photon counters. Whilst the high granularity provides a powerful toolset to discriminate backgrounds; by itself the segmentation also represents a challenge in terms of homogeneity and calibration, for a consistent detector response. The search for this light sterile neutrino implies a sensitivity to distortions of around $\mathcal{O}$(10)\% in the energy spectrum of reactor $\overline{\nu}_e$. Hence, a very good neutron detection efficiency, light yield and homogeneous detector response are critical for data validation. The minimal requirements for the SoLid physics program are a light yield and a neutron detection efficiency larger than 40 PA/MeV/cube and 50 \% respectively. In order to guarantee these minimal requirements, the collaboration developed a rigorous quality assurance process for all 12800 cubic cells of the detector. To carry out the quality assurance process, an automated calibration system called CALIPSO was designed and constructed., Comment: Submitted to JINST

This paper presents a comprehensive optimisation study to maximise the light collection efficiency of scintillating cube elements used in the SoLid detector. Very short baseline reactor experiments, like SoLid, look for active to sterile neutrino oscillation signatures in the anti-neutrino energy spectrum as a function of the distance to the core and energy. Performing a precise search requires high light yield of the scintillating elements and uniformity of the response in the detector volume. The SoLid experiment uses an innovative hybrid technology with two different scintillators: polyvinyltoluene scintillator cubes and $^6$LiF:ZnS(Ag) screens. A precision test bench based on a $^{207}$Bi calibration source has been developed to study improvements on the energy resolution and uniformity of the prompt scintillation signal of antineutrino interactions. A trigger system selecting the 1~MeV conversion electrons provides a Gaussian energy peak and allows for precise comparisons of the different detector configurations that were considered to improve the SoLid detector light collection. The light collection efficiency is influenced by the choice of wrapping material, the position of the $^6$LiF:ZnS(Ag) screen, the type of fibre, the number of optical fibres and the type of mirror at the end of the fibre. This study shows that large gains in light collection efficiency are possible compared to the SoLid SM1 prototype. The light yield for the SoLid detector is expected to be at least 52$\pm$2 photo-avalanches per MeV per cube, with a relative non-uniformity of 6 %, demonstrating that the required energy resolution of at least 14 % at 1 MeV can be achieved., 25 pages, 19 figures, published in JINST 2018_JINST_13_P09005

Molecular-dynamics simulations were used to calculate threshold displacement energies for each atom type in BaTiO 3 perovskite. A primary knock-on atom with an energy range between 10 and 300 eV in principal crystallographic directions at 300 K was introduced. A statistical approach has been applied calculating displacement probability curves along main crystallographic directions. For each sublattice, the simulation was repeated from different initial conditions to estimate the uncertainty in the threshold displacement energy calculated values. The threshold displacement energies vary considerably with crystallographic direction and sublattice. The weighted average threshold displacement energies are 40 eV for oxygen, 64 eV for barium and 97 eV for titanium atoms. These values are comparable to ab initio calculated and experimentally derived values in perovskites. These results are proposed as threshold displacement energies, ideal for simulation programs that use atomic displacement calculation algorithms.

The radiation damage, in terms of atom displacements, induced by gamma irradiation in LYSO and LuYAP crystals is presented. Sc-44, Na-22 and V-48 are used as gamma sources for this study. The energy of gammas from the electron positron annihilation processes (511 keV) is also included in the study. The atom displacements distributions inside each material are calculated following the Monte Carlo assisted Classical Method introduced by the authors. This procedure also allows to study the atom displacements in-depth distributions inside each crystal. The atom displacements damage in LYSO crystals is found to be higher than in LuYAP crystals, mainly provoked by the displacements of silicon and oxygen atoms. But the difference between atom displacements produced in LYSO and LuYAP decreases when more energetic sources are used. On the other hand, the correlation between the atom displacements and energy deposition in-depth distributions is excellent. The atom displacements to energy deposition ratio is found to increases with more energetic photon sources. LYSO crystals are then more liable to the atom displacements damage than LuYAP crystals. (C) 2015 Elsevier B.V. All rights reserved.

The SoLid collaboration has developed a new detector technology to detect electron anti-neutrinos at close proximity to the Belgian BR2 reactor at surface level. A 288$\,$kg prototype detector was deployed in 2015 and collected data during the operational period of the reactor and during reactor shut-down. Dedicated calibration campaigns were also performed with gamma and neutron sources. This paper describes the construction of the prototype detector with a high control on its proton content and the stability of its operation over a period of several months after deployment at the BR2 reactor site. All detector cells provide sufficient light yields to achieve a target energy resolution of better than 20%/$\sqrt{E(MeV)}$. The capability of the detector to track muons is exploited to equalize the light response of a large number of channels to a precision of 3% and to demonstrate the stability of the energy scale over time. Particle identification based on pulse-shape discrimination is demonstrated with calibration sources. Despite a lower neutron detection efficiency due to triggering constraints, the main backgrounds at the reactor site were determined and taken into account in the shielding strategy for the main experiment. The results obtained with this prototype proved essential in the design optimization of the final detector. This paper is dedicated to our SCK$\cdot$CEN colleague, Edgar Koonen, who passed away unexpectedly in 2017. Edgar was part of the SoLid collaboration since its inception and his efforts were vital to get the experiment started. He will be duly missed., 29 pages, 23 figures, submitted to JINST

Several authors had estimated the displacements per atom cross sections under different approximations and models, including most of the main gamma- and electron-material interaction processes. These previous works used numerical approximation formulas which are applicable for limited energy ranges. We proposed the Monte Carlo assisted Classical Method (MCCM), which relates the established theories about atom displacements to the electron and positron secondary fluence distributions calculated from the Monte Carlo simulation. In this study the MCCM procedure is adapted in order to estimate the displacements per atom cross sections for gamma and electron irradiation. The results obtained through this procedure are compared with previous theoretical calculations. An improvement in about 10-90% for the gamma irradiation induced dpa cross section is observed in our results on regard to the previous evaluations for the studied incident energies. On the other hand, the dpa cross section values produced by irradiation with electrons are improved by our calculations in about 5-50% when compared with the theoretical approximations. When thin samples are irradiated with electrons, more precise results are obtained through the MCCM (in about 20-70%) with respect to the previous studies. (C) 2014 Elsevier B.V. All rights reserved.

Nowadays the electronic structure calculations allow the study of complex systems determining the hyperfine parameters measured at a probe atom, including the presence of crystalline defects. The hyperfine electric parameters have been measured by Mossbauer spectroscopy in silicon materials implanted with Mn 57 → Fe 57 ions, observing four main contributions to the spectra. Nevertheless, some ambiguities still remain in the 57Fe Mossbauer spectra interpretation in this case, regarding the damage configurations and its evolution with annealing. In the present work several implantation environments are evaluated and the 57Fe hyperfine parameters are calculated. The observed correlation among the studied local environments and the experimental observations is presented, and a tentative microscopic description of the behavior and thermal evolution of the characteristic defects local environments of the probe atoms concerning the location of vacancies and interstitial Si in the neighborhood of 57Fe ions in substitutional and interstitial sites is proposed.

Magnetic state of Fe-57 implanted and doped ZnO samples have been reported and studied by Mossbauer spectroscopy at different temperatures. The Mossbauer spectra mainly showed four doublets and three sextets, but some ambiguous identification remains regarding the probe site location and influence of defects in the hyperfine and magnetic parameters. In the present work some possible implantation configurations are suggested and evaluated using Monte Carlo simulation and electronic structure calculations within the density functional theory. Various implantation environments were proposed and studied considering the presence of defects. The obtained Fe-57 hyperfine parameters show a good agreement with the reported experimental values for some of these configurations. The possibility of Fe pair formation, as well as a Zn site vacancy stabilization between he second and third neighborhood of the implantation site, is supported. (C) 2014 Elsevier Ltd. All rights reserved.

The next generation of very-short-baseline reactor experiments will require compact detectors operating at surface level and close to a nuclear reactor. This paper presents a new detector concept based on a composite solid scintillator technology. The detector target uses cubes of polyvinyltoluene interleaved with $^6$LiF:ZnS(Ag) phosphor screens to detect the products of the inverse beta decay reaction. A multi-tonne detector system built from these individual cells can provide precise localisation of scintillation signals, making efficient use of the detector volume. Monte Carlo simulations indicate that a neutron capture efficiency of over 70% is achievable with a sufficient number of $^6$LiF:ZnS(Ag) screens per cube and that an appropriate segmentation enables a measurement of the positron energy which is not limited by gamma-ray leakage. First measurements of a single cell indicate that a very good neutron-gamma discrimination and high neutron detection efficiency can be obtained with adequate triggering techniques. The light yield from positron signals has been measured, showing that an energy resolution of 14%/$\sqrt{E({\mathrm{MeV}})}$ is achievable with high uniformity. A preliminary neutrino signal analysis has been developed, using selection criteria for pulse shape, energy, time structure and energy spatial distribution and showing that an antineutrino efficiency of 40% can be achieved. It also shows that the fine segmentation of the detector can be used to significantly decrease both correlated and accidental backgrounds., 17 pages, 15 figures, submitted to JINST

The Monte Carlo assisted Classical Method (MCCM) consists on a calculation procedure for determining the displacements per atom (dpa) distribution in solid materials. This algorithm allows studying the gamma and electron irradiation damage in different materials. It is based on the electrons elastic scattering classic theories and the use of Monte Carlo simulation for the physical processes involved. The present study deals with the Monte Carlo simulation of electron irradiation effects on YBa2Cu3O7-x (YBCO) slabs using the MCNPX code system. Displacements per atom distributions are obtained through the MCCM for electron irradiation up to 10 MeV. In-depth dpa profiles for electrons and positrons are obtained and analysed. Also, dpa contributions from each atomic specie in the material are calculated. It was found that the dpa distribution is more homogeneous in the material volume when increasing energy of incident electrons. Also, the dpa produced by positrons has no relevance when irradiating with electrons, in contrast with previous similar gamma irradiation studies. All the results are presented and discussed in this contribution. (C) 2011 Elsevier B.V. All rights reserved.

A first-principles study of the electric field gradient (EFG) calculated for ideal and In-111(Cd-111) implanted ZnO samples is reported in the present work. The study was made for ZnO ideal hexagonal structures and supercells were introduced in order to consider the possible implantation environments. The calculation was done using the "WIEN2k" code within the density functional theory, the exchange and correlation effects were determined by the GGA approximation. Three possible In-111(Cd-111) implantation configurations were studied, one substitutional incorporation at cation site and two interstitials. The obtained EFG values for the ideal structure and the substitutional site are in good agreement with the experimental reports measured by perturbed angular correlation (PAC) and high precision nuclear magnetic resonance (NMR). Thus, the ascription of substitutional incorporation of In-111(Cd-111) probe atom at the ZnO cation site after annealing was confirmed. (C) 2011 Elsevier Ltd. All rights reserved.

The present work reports the results of a first study of elemental composition in airborne particulate matter (fine and coarse) collected at the Municipality of Centro Habana, Havana City, Cuba, using the PIXE technique. At present, there is not any information available about element contents in airborne particulate matter from this region. A five months sampling campaign was carried out, collecting the samples under an air flux of 20 l/min with a Gent SFU Sampler equipped with a system which allows the aerosol collection in both size fractions simultaneously. A total of 144 aerosol samples were collected. For the PIXE analysis, the samples were irradiated by 2.0 MeV energy protons from a 2MV Tandetron Accelerator. A total of 14 elements ( S , Cl , K , Ca , Ti , V , Cr , Mn , Fe , Ni , Cu , Zn , Br and Pb ) were consistently detected with minimum detection limits from 1 ng/m3 to 10 ng/m3 for most of the elements. Enrichment factors were also calculated for both fractions in order to identify the natural and anthropogenic group of elements. The quantitative results obtained have revealed important information that has been used in a first attempt to understand and to characterize the atmospheric pollution of this area.

The contribution from positrons to the displacements per atom (dpa) distribution induced by the gamma irradiation on YBCO superconducting slabs is presented. The procedure implemented previously by the authors was adapted to take into account the contribution from positrons to dpa induced by the gamma radiation. The results show that, when positrons are considered in the atom displacement process, the total dpa almost doubles at 10 MeV of incident gamma radiation. At that energy positrons contribute 7% more to the total dpa than electrons, although electrons maintain having the highest contribution up to about 8 MeV.

The results of the calculations of the displacements per atom distribution induced by the gamma irradiation up to 15 MeV on YBa 2 Cu 3 O 7− x superconducting slabs are presented. Firstly, a calculation procedure for the displacement cross sections and the displacement per atom distributions was applied using the Monte Carlo simulation through the MCNPX code system. Then, based on this algorithm, the displacement per atom in-depth distributions were calculated starting from the energy flux distributions obtained from the simulation process, taking into account the contribution from each atom, obtaining a predominance of the Cu–O 2 planar sites over yttrium and barium atoms and more specifically the oxygen atoms predominate at low energies and the copper atoms at higher energies. Finally, the linear correlation observed between the displacement per atom distributions and energy deposition profiles at each incident energy was analyzed.

The calculation results of the atom displacement distribution induced by gamma radiation in the superconducting material YBa2Cu3O7–x are presented. Firstly, a direct calculation procedure for the atom displacement distribution inside a given material is introduced, starting from the application of the energy flux distribution values of secondary electrons, formerly calculated using the Monte Carlo method based code system MCNP-4C. Finally, calculation results of the atom displacement distribution, regarding the occupied oxygen crystalline sites, are presented for different incident gamma radiation energies, where an atom displacement threshold energy value of 20 eV was assigned to O(1–3) sites, while a value of 3.45 eV was used for the copper–oxygen chain sites at the basal plane. According to the present calculations, a predominating atom displacement rate at copper-oxygen chain sites was obtained. On the other hand, nearly linear correlations among atom displacements and energy deposition profiles were also found. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Bi 2 Sr 2 CaCu 2 O x superconducting thin rods textured by the laser floating zone melting method were irradiated with 1250 and 662 keV γ rays. The behavior of some of its superconducting properties with the exposure dose was studied by the measurement of dynamic magnetic susceptibility. It was observed that, for different dose levels according to the energy of the incident radiation, the rods preserve their superconducting intragrain properties, evidencing the high resistance of the material to the γ radiation damage. In all the cases it was verified that, with increasing exposure dose, the onset temperature of the superconducting transition increases. The possible mechanisms that should take place are analyzed in the text. The χ ac measurements also show the increasing behavior of the superconducting volume fraction in the sample with the exposure dose.

Present contribution deals with Monte Carlo simulation of atom displacements rates resulting in solids based on a calculation algorithm supporting the description of the conditions favouring the occurrence of single fast electron elastic scattering in solids, leading to the displacement of atoms from their crystalline sites. Firstly, a McKinley-Feshbach differential cross-section renormalization is introduced by considering single elastic scattering events with scattering angles only within the interval [θ l , π], where θ l is the limiting angle, under which multiple scattering events with relative low scattering angles prevails over the single ones. On this basis, a Monte Carlo simulation code (MCSAD) of atom displacements induced by electrons and photons was implemented. In particular, total atom displacements produced along an electron travelling path were sampled in different solids matrix and compared with Oen-Holmes-Cahn theory predictions at different electron initial energies. As a result, it was concluded that Oen-Holmes-Cahn calculations overestimate normalized atom displacements rates in comparison with present MCSAD ones in a range up to between 10 to 73% rate, where maximum deviation were observed in YBCO for heaviest atom. It was also found that Oen-Holmes-Cahn absolute atom displacements distributions overestimated in about 30 to 40 times at the maximum of the AD rate simulated by MCSAD code.

The aim of the present work is to study the radiation damage induced in LYSO and LuYAP crystals by the gamma radiation and the secondary electrons/positrons generated. The displacements per atom (dpa) distributions inside each material were calculated following the Monte Carlo assisted Classical Method (MCCM) introduced by the authors. As gamma sources were used Sc-44, Na-22 and V-48. Also the energy of gammas from the annihilation processes (511 keV) was included in the study. This procedure allowed studying the in-depth dpa distributions inside each crystal for all four sources. It was also possible to obtain the separate contribution from each atom to the total dpa. The LYSO crystals were found to receive more damage, mainly provoked by the displacements of silicon and oxygen atoms.

The radiation damage created in silicon materials by Mn-57 -> Fe-57 ion implantation has been studied and characterized by Mossbauer spectroscopy showing four main lines, assigned to: substitutional, interstitial and damaged configuration sites of the implanted ions. Nevertheless, the Mossbauer spectrum of Fe-57 in this materials remains with some ambiguous identification regarding the implantation configurations before and after annealing, specially the damaged configurations and its evolution. In the present work some possible implantation configurations are suggested and evaluated using a multiscale approach by Monte Carlo ion transport and electronic structure calculations within DFT. The proposed implantation environments were evaluated in terms of stability and the Fe-57 hyperfine parameters were calculated to establish the connections with the experimental observations. Good agreement was found between the experimental and the calculated hyperfine parameters for some configurations; suggesting which ones could be the implantation environments before and after sample annealing.

"El presente trabajo sintetiza los resultados experimentales obtenidos en la caracterización de un detector de silicio cristalino de 64 microbandas diseñado para experimentos de física de las altas energías, con el objetivo de estudiar su posible aplicación en la imagenelogía médica, específicamente en mamografía y angiografía digital. La Investigación incluyó la obtención de radiografías bidimensionales de un maniquí mamográfico empleando el método de barrido y su comparación con similares resultados simulados matemáticamente para diferentes fuentes de rayos X. También se presentan las imágenes reales obtenidas luego de radiografiar dos muestras de tejido biológico tomadas de biopsias de mamas, donde se identifica la existencia de un tipo de lesion pretumoral. Los resultados alcanzados apuntan positivamente hacia la posibilidad real de que estos detectores de avanzada puedan ser satisfactoriamente introducidos en la obtención de imágenes radiográficas digitales médicas."

Present contribution deals with the theoretical description of the conditions favoring the occurrence of single fast electron elastic scattering in solids, leading to the displacement of atoms from their crystalline sites.

In the present work the extended Monte Carlo assisted Classical Method (MCCM) is presented. The method consists on a calculation procedure for the determination of the displacements per atom (dpa) distribution in solid materials, which allows studying the gamma irradiation damage in different materials. The same one is based on the electrons elastic scattering classic theories and makes use of the Monte Carlo simulation of physical processes involved in the radiation interactions with substance. Recently, the contribution from positrons to dpa distributions has been also included. This method has been applied to different materials: metals (iron), semiconductors (Si and CZT) and high temperature superconductors like YBCO. Among other things, this procedure has allowed to study the dpa cross sections and the in-depth dpa distributions in a wide range of incident gamma energies. Also in compound materials, the contribution from each atomic species is possible to be evaluated.

The present paper synthesizes the results obtained in the evaluation of a 64 microstrips crystalline silicon detector coupled to RX64 ASIC, designed for high‐energy physics experiments, as a useful X‐ray detector in advanced medical radiography, specifically in digital mammography. Research includes the acquisition of two‐dimensional radiography of a mammography phantom using the scanning method, and the comparison of experimental profile with mathematically simulated one. The paper also shows the experimental images of three biological samples taken from breast biopsies, where it is possible to identify the presence of possible pathological tissues.

During the earliest tests of a free‐air ionization chamber a poor response to the X‐rays emitted by several sources was observed. Then, the Monte Carlo simulation of X‐rays transport in matter was employed in order to evaluate chamber behavior as X‐rays detector. The photons energy deposition dependence with depth and its integral value in all active volume were calculated. The obtained results reveal that the designed device geometry is feasible to be optimized.