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In the context of the COVID-19 pandemic, French public opinion has been divided about Pr. Didier Raoult and his hydroxychloroquine-based treatment against COVID-19. In this paper, our aim is to contribute to the understanding of this polarization of public opinion by investigating the relationship between (analytic vs. intuitive) cognitive style and trust in Didier Raoult and his treatment. Through three studies (totalNafter exclusion = 950), we found that a more intuitive cognitive style predicted higher trust in Didier Raoult and his treatment. Moreover, we found that Trust in Raoult was positively associated with belief that truth is political, belief in conspiracy theories, belief in pseudo-medicines and pseudo-medical and conspiratorial beliefs regarding the COVID-19 pandemic. We also found a negative association with knowledge of scientific methods and regard for scientific method over personal experience. However, higher trust in Didier Raoult was not associated with self-reported compliance with official regulations concerning the COVID-19 pandemic.

CUORE Upgrade with Particle IDentification (CUPID) is a foreseen ton-scale array of Li2MoO4 (LMO) cryogenic calorimeters with double readout of heat and light signals. Its scientific goal is to fully explore the inverted hierarchy of neutrino masses in the search for neutrinoless double beta decay of 100Mo. Pile-up of standard double beta decay of the candidate isotope is a relevant background. We generate pile-up heat events via injection of Joule heater pulses with a programmable waveform generator in a small array of LMO crystals operated underground in the Laboratori Nazionali del Gran Sasso, Italy. This allows to label pile-up pulses and control both time difference and underlying amplitudes of individual heat pulses in the data. We present the performance of supervised learning classifiers on data and the attained pile-up rejection efficiency.

Charge trapping phenomena and recombination centers were studied in three Cs2HfCl6 single crystals of slightly different stoichiometry grown by the vertical Bridgeman method. Electron paramagnetic resonance (EPR) spectra measured both before and after X-ray irradiation show creation of two distinct Vk centers. One of them was Vk(a) already known from a recent work by “R. Král, V. Babin, E. Mihoková, M. Buryi, V. V. Laguta, K. Nitsch, and M. Nikl, Luminescence and Charge Trapping in Cs2HfCl6 Single Crystals: Optical and Magnetic Resonance Spectroscopy Study, J. Phys. Chem. C 121, 12375–12382 (2017)”. Its quantity was different in each of the samples studied; the smallest, however, was in the one with the best stoichiometry. The second Vk center presently observed has never been described before. Its existence at an almost undetectable level was observed only in two of the three crystals. Thermally stimulated luminescence (TSL) spectra measured in the three samples were evidently composed of at least 2–3 strongly overlapped components within the 10–500 K temperature range. This suggested the existence of several recombination centers activated by the depletion of specific charge carrier traps. The corresponding TSL glow curves composed of seven complex peaks demonstrated significant decrease of the peaks amplitude in the sample with the best stoichiometry. Along with decreased radioluminescence amplitude, the combined EPR and TSL study allowed us to assume the reduction of both the recombination and trap center concentration with the increased crystal quality

International audience; The carrier trapping and recombination mechanisms occurring in Ce-doped silica fibers, produced by a sol-gel technique, are investigated by combining temperature-dependent steady-state X-ray-excited luminescence, wavelength- and time-resolved scintillation measurements, and wavelength-resolved thermally stimulated luminescence, focusing especially on the temperature range from 10 to 320 K. The scintillation decay features a decay time of the order of tens of nanoseconds, characteristic of the parity- and spin-allowed 5d-4f radiative transition of Ce3+ ions. In addition, a slow and complex decay contribution in the microsecond timescale is detected. We interpret these features as due to the radiative recombination at Ce centers of carriers freed from a continuous distribution of trapping sites in the forbidden gap as well as to the occurrence of an athermal tunneling recombination process between traps and Ce3+ ions. This interpretation is reinforced by good agreement between independent evaluations of trap depths and lifetimes obtained by both the numerical analysis of scintillation time decays and thermally stimulated luminescence experiments.

Lead halide perovskites (LHP) are rapidly emerging as efficient, low-cost, solution-processable scintillators for radiation detection. Carrier trapping is arguably the most critical limitation to the scintillation performance. Nonetheless, no clear picture of the trapping and detrapping mechanisms to/from shallow and deep trap states involved in the scintillation process has been reported to date, as well as on the role of the material dimensionality. Here, this issue is addressed by performing, for the first time, a comprehensive study using radioluminescence and photoluminescence measurements side-by-side to thermally-stimulated luminescence (TSL) and afterglow experiments on CsPbBr3 with increasing dimensionality, namely nanocubes, nanowires, nanosheets, and bulk crystals. All systems are found to be affected by shallow defects resulting in delayed intragap emission following detrapping via a-thermal tunneling. TSL further reveals the existence of additional temperature-activated detrapping pathways from deeper trap states, whose effect grows with the material dimensionality, becoming the dominant process in bulk crystals. These results highlight that, compared to massive solids where the suppression of both deep and shallow defects is critical, low dimensional nanostructures are more promising active materials for LHP scintillators, provided that their integration in functional devices meets efficient surface engineering.

The influence of fiber drawing on mechanical and vibrational properties of RE-doped sol-gel silica is disclosed by a comparison of bulk silica, before and after the melting process, and fibers. The mechanical characterization is carried out by nanoindentation technique: hardness and elastic modulus are found to be consistent with those of Corning 7980 reference glass, and related to the elasto-plastic behavior of the glassy material. Our results evidence an increase of the resistance of fibers to fracture under an applied load, ascribed to drawing-induced residual stresses. Their impact on sol-gel silica mechanical properties is further disclosed by complementary vibrational characterization by Raman and FTIR spectroscopies, confirming the occurrence of a modification of the structural features after the drawing process and of residual stresses in the fibers. The overall results highlight the role of the fiber drawing in improving the glass mechanical properties, causing a slight rearrangement of the silica structure.

7Li enriched Cs2LiYCl6:Ce3+ (CLYC) is a promising inorganic scintillator for real-time γ-ray and fast neutron spectrometry. The neutron/γ-ray discrimination is usually accomplished exploiting the different quenching effects of high Linear Energy Transfer (LET) particles on different scintillation mechanisms, usually by means of the time analysis of the pulse shape. In principle, the emission wavelength information could be used to address the same task. However, a systematic study of the correlations between the CLYC decay time, its radio-luminescence spectrum and the LET of the impinging particle has not yet been performed. We therefore investigated the CLYC scintillation process under neutron and γ-ray irradiation, correlating the time response to the scintillation wavelength spectrum using a 1–inch right cylinder>99% 7Li enriched CLYC. We found that the relative intensity of the Core to Valence Luminescence (CVL) is almost constant with photons in the energy range 20–660 keV, i.e. 0.5–5 keV/μm LET, and is only partially quenched by neutrons. Instead, the direct electron-hole capture scintillation mechanism is completely cut under neutron irradiation. The luminescence in between the deep-Ultraviolet and the Near Ultraviolet region (250–350 nm) might be attributed to both the CVL and the host luminescence, also in thick highly Ce3+-doped crystals.

A PbMoO4 single crystal as a perspective detector for neutrinoless double beta decay experiment was grown by the Czochralski technique from high purity raw materials including archaeological lead. Charge trapping and energy transfer phenomena in this crystal have been studied by electron paramagnetic resonance (EPR) and wavelength-resolved thermally stimulated luminescence (TSL). EPR revealed several impurities, which however do not participate in the charge trapping processes: Gd3+, Cr3+, Mn2+. Self-trapped electron and (MoO4)3--VPb centers creation under laser light was confirmed. At least six glow peaks related to the thermal release of the charge carriers were observed having maxima at 41 K, 53 K, 83 K, 90 K, 105 K and 118 K. The peak at 41 K was ascribed to the de-trapping of self-trapped electrons. The 53 K one, in particular, is created by re-trapping processes. Partial cleaning procedure followed by the initial rise method allow to determine the trap depths and frequency factors for the 90 K and 105 K glow peaks. They have been referred to the (MoO4)3--VPb decay. A three-component analysis of the spectra could explain the observed 100 nm red shift of the thermo-luminescence emission maximum.

International audience; The generation of silver species has been investigated in silver containing sodo‐gallo‐phosphate glasses subjected to X‐rays irradiations. Radio‐luminescence spectroscopy has evidenced the presence of isolated and paired silver ions. The proportion of silver pairing is found dominant in ortho‐phosphate glass compositions, compared to poly‐phosphate counterparts. The phosphate glass network is reported to have a decisive impact on the X‐Ray photosensitivity and the formation of luminescent silver species, namely Ag2+ hole trap silver ions and Agmx+ silver clusters. The subsistence of femtosecond laser produced silver luminescent structures under X‐Ray irradiation has been demonstrated.

In this study, we propose an original approach for particle discrimination in a mixed radiation field using scintillators. The method relies on the possibility to identify the point of interaction in a phoswich detector from the emission spectra of the produced scintillation light, using optical filters as passive selectors. As a proof of concept, we developed a compact prototype thermal neutron active dosimeter for mixed neutron/gamma fields. The detector was characterized in terms of energy calibration, neutron efficiency and gamma rejection. The obtained results show that more than the 99% of counts due to gamma rays are rejected if the color discrimination is employed, thus demonstrating the feasibility of the proposed approach to be used in radiation detection.

Journal of geophysical research / Planets 125(1), 1-19 (2020). doi:10.1029/2019JE006176, Gibbs energy representations for ices II, III, V, and VI are reported. These were constructed using new measurements of volumes at high pressure over a range of low temperatures combined with calculated vibrational energies grounded in statistical physics. The collection of representations are released within the open source SeaFreeze program, together with the Gibbs representation already known for ice Ih and water. This program allows accurate determination of thermodynamics properties (phase boundaries, density, specific heat, bulk modulus, thermal expansivity, chemical potentials) and seismic wave velocities over the entire range of conditions encountered in hydrospheres in our solar system (130���500 K to 2,300 MPa). These comprehensive representations allow exploration of the rich spectrum of thermodynamic behavior in the H$_2$O system. Although these results are broadly applicable in science and engineering, their use is particularly relevant to habitability analysis, interior modeling, and future geophysical sounding of water���rich planetary bodies of our solar system and beyond., Published by Wiley, Hoboken, NJ

A new inorganic scintillation material based on Ba-Gd silica glass doped with cerium (BGS) is fabricated and studied. With the highest light yield among heavy glasses at the level of 2500 ph/MeV and fast scintillation response, the new scintillator ensures a good coincidence time resolution of γ -quanta from a 22Na source and SiPM readout. In addition to good performance in γ -quanta detection, the material demonstrates capability for efficient detection of low-energetic​ neutrons. The scintillator is produced by exploiting the standard industrial glass technology, which allows for an unlimited scaling up the conversion of raw material into a high-quality scintillator at a high rate. The glass can be casted in application-specific molds, so minimizing the material losses. The presented glass scintillator has potential for further improvement of its light output and scintillation response time.

Room temperature angle dispersive powder x-ray diffraction experiments on zircon-type NdVO

The results of irradiation tests on Ce-doped sol-gel silica using X- and g-rays up to 10 kGy are reported, in order to investigate the radiation hardness of this material for high energy physics applications. Sol-gel silica fibers with Ce concentrations of 0.0125 mol% and 0.05 mol% are characterized by means of optical absorption and attenuation length measurements before and after irradiation. The two different techniques give comparable results, evidencing the formation of a main broad radiation-induced absorption band, peaking at about 2.2 eV, related to radiation-induced color centers. The results are compared with those obtained on bulk silica. This study reveals that an improvement of the radiation hardness of Ce-doped silica fibers can be achieved by reducing Ce content inside the fiber core, paving the way for further material development.

Ce-doped garnets find their use as scintillators as well as phosphors. Among synthetic garnets, gallium gadolinium aluminium garnet (GGAG) is a relatively new and interesting material, a mixed garnet that has displayed very good scintillation and luminescence properties. In the presented work Ce-doped GGAG ceramic samples were produced by reaction sintering from commercial oxide powders. The mixed powders were pressed into pellets and sintered. In order to achieve transparency of a ceramic material, it is crucial to eliminate porosity. Therefore, a number of process parameters and their influence on the microstructure and optical quality of the ceramics were studied: starting powders, sintering additives and sintering conditions. The sintering process consisted of two steps, viz. pressureless sintering in air followed by hot isostatic pressing. Luminescence properties of the sintered ceramics were studied by means of photo-luminescence and correlated to the fabrication process parameters.

In recent years, oxide materials based on garnet structure are being investigated as very promising candidates in the field of scintillation because of their high density, good chemical stability, optical transparency, and the possibility to easily incorporate luminescent rare-earth ions. Several studies demonstrated that garnet crystals show high light yield and advantageous timing performances, which make them of interest for applications in medical imaging and high energy physics detectors [1]. Among synthetic garnets, Ce-doped gadolinium gallium aluminum garnet (GGAG:Ce) is a relatively new and interesting material. It is a mixed garnet that has displayed very good scintillation and luminescence properties: its high density enhances the interaction with ionizing radiation, and the presence of Gd provides a high cross section for thermal neutron capture [2]. GGAG:Ce preserves a crystalline cubic structure, which allows to produce it in the form of transparent polycrystalline ceramic [3] with favorable characteristics for optical applications such as lasers, LEDs, and scintillators. In this work, ceramic samples were produced by reaction sintering from commercial oxide powders: the mixed powders were pressed into pellets and sintered by a combined process of air sintering and hot isostatic pressing. The sintering process was carefully selected and the use of sintering additives was optimized to eliminate porosity, which is crucial to achieve a good optical transparency. Optical properties were studied by means of optical absorption spectroscopy, steady-state and time resolved photo- and radio- luminescence, and correlated to the fabrication process parameters. Moreover, trapping phenomena caused by the presence of point defects were investigated by wavelength resolved thermally stimulated luminescence in a wide temperature range (10 - 800 K); a significant persistent luminescence signal was also singled out and investigated as a function of temperature. The presence of point defects was also evidenced by the occurrence of a sensitization of the radio-luminescence signal as a function of increasing cumulated X-ray dose, related to a competitive process between traps and Ce recombination centers in free carrier capture. Finally, preliminary results on recently developed layered Y3Al5O12:Pr/Gd3(Ga,Al)5O12:Ce (YAG:Pr/GGAG:Ce) ceramics for particle detection and discrimination will be also reported. This work has been supported by H2020 European Institute for Innovation and Technology (EIT) SPARK project (16290) and H2020 Rise project INTELUM (644260). [1] M. T. Lucchini et al., Nucl. Instrum. Methods Phys. Res. A 816 (2016) 176-183 [2] J. Dumazert et al., Nucl. Inst. Methods Phys. Res. A 882 (2018) 53 [3] Y. Ye et al., Opt. Mater. 71 (2017) 23

KLuS2 single crystal samples undoped and doped with a low (5 %) or high (38 %) concentration of trivalent thulium or ytterbium ions were synthesized in the form of thin hexagonal plates. The low phonon energy ( ∼ 220 cm−1) was confirmed using Raman spectroscopy. Samples were studied also by using optical absorption and emission as well as electron paramagnetic resonance spectroscopy and the observed spectral features are discussed. In particular, the 5 % Yb doped samples demonstrate homogeneous dopant distribution inside the material over the lutetium sites. No other signals either from potassium site or the exchange coupled ions were detected. For infrared transitions the luminescence kinetic was determined. Significantly broad infrared emission bands (at 1.4, 1.8 and 2.3 μm for Tm3+, 1 μm for Yb3+) and long decay times (e.g. 0.4 ms from 3H4 to 19 ms from 3F4 levels of Tm3+, 1.4 ms from 2F5/2 level of Yb3+) make those materials perspective for future laser development.

Ce-doped garnets find their use as scintillators as well as phosphors. Among synthetic garnets, gallium gadolinium aluminum garnet (GGAG) is a relatively new and interesting material, a mixed garnet that has displayed very good scintillation and luminescent properties [1]. In the presented work GGAG ceramic samples were produced by reaction sintering from commercial oxide powders. The mixed powders were pressed into pellets and sintered. In order to achieve transparency of a ceramic material, it is crucial to eliminate porosity. Therefore, the sintering process was carefully selected and the use of sintering additives was studied. The sintering process consisted of two steps, viz. sintering in air followed by hot isostatic pressing. The influence of starting powders, sintering additives and sintering conditions on the microstructure and optical quality of the ceramics was studied. Fig. 1 shows one of the ceramic samples and its microstructure. Luminescence properties were studied by means of photo- and radio-luminescence and correlated to the fabrication process parameters. In some of the samples, significant persistent luminescence was observed and studied. Moreover, point defects were investigated by thermally stimulated luminescence, also in comparison with a single crystal with the same composition. [1] Y. Wu, F. Meng, Q. Li, M. Koschan, C. L. Melcher. Role of Ce4+ in the scintillation mechanism of codoped Gd3Ga3Al2O12:Ce. Phys. Rev. Appl. 2 (2014) 044009.

Carbon capture and storage using regenerable sorbents are an effective approach to reduce CO

Scintillating silica optical fibre sensors have shown interesting results for ionizing radiation monitoring and therefore can be useful for dosimetry applications in medical field. In fact, they enable a remote, punctual and real-time dose assessment (Mones et al., 2008). In addition, the high radiation hardness that characterizes silica optical fibers, makes these systems promising for radiation detection in high energy physics experiments (Chiodini et al., 2014). This work aims to review the recent progresses in the development and characterization of rare-earth doped silica fibres. The radioluminescent and dosimetric properties of Ce, Eu, Yb and Pr-doped silica matrices are described and the advantages and challenges in the use of these materials for dosimetry in medical and technical applications are shown. In radiation therapy, an effective approach to deal with the stem effect, that is a spurious luminescent signal in the UV-VIS region due to the irradiation of the passive fibre (i.e. Cerenkov light and intrinsic fluorescence) must be considered. The opportunity to use Yb as dopant and to exploit its near infrared emission for the stem effect optical discrimination is presented (Veronese et al., 2014). In the field of high energy physics, radioluminescent optical fibres could find applications in future detectors and calorimeters. The possible choice of Pr as dopant, in view of its fast scintillation time is described and discussed.

Particle discrimination in a mixed radiation field using scintillators is a challenging topic in radiation detection research. We propose a novel approach relying on the possibility of identifying particles interacting in a phoswich detector from the emission spectrum of the produced scintillation signal. As a proof of concept, we focus on the discrimination between neutrons and gamma rays. Lu 3 Al 5 O 12 :Pr and Gd 3 Al 2 Ga 3 O 12 :Ce thin single crystal scintillators, coupled to two different silicon photomultipliers equipped with optical filters, are simultaneously used in the same phoswich detector. Their optical emissions peak at approximately 310 nm and 545 nm respectively, and thus they can easily be distinguished by optical filtering. While both crystals are sensitive to gamma rays, neutrons interact only with the Gd 3 Al 2 Ga 3 O 12 :Ce thanks to the presence of Gd acting as neutron converter. Optical filtration and an anti-coincidence algorithm are therefore used to perform particle discrimination, rejecting coincidence signals arising from gamma rays, which simultaneously deposit energy in both crystals, and counting anti-coincidence signals due to neutrons, which deposit energy only in the Gd 3 Al 2 Ga 3 O 12 :Ce. The simple neutron counter developed here is intended to be a proof of the principle of the feasibility of the color-based particle discrimination technique.

Lithium fast-ion conductors have shown positive effects on the hydrogen storage properties of the Li-Mg-N-H system. In the present work, Li4(NH2)3BH4 doped Mg(NH2)2-2LiH was formed by milling the 2LiNH2-MgH2-0.2LiBH4 composite and posterior annealing under hydrogen pressure to reduce the kinetic barrier of the Li-Mg-N-H system. The effect of repetitive dehydrogenation/rehydrogenation cycles on the kinetic and thermodynamic performance was evaluated. The dehydrogenation rate in the doped composite was twice that in the un-doped sample at 200 °C, while hydrogenation was 20 times faster. The activation energy decreases by 9% due to the presence of Li4(NH2)3BH4 compared to the un-doped composite, evidencing its catalytic role. The presence of Li4(NH2)3BH4 in the composite stabilized the hydrogen storage capacity after successive sorption cycles. Thermodynamic studies revealed a variation in the pressure composition isotherm curves between the first dehydrogenation cycle and the subsequent. The Li4(NH2)3BH4 doped composite showed a sloped plateau region at higher equilibrium pressure in regard to the flat plateau of the un-doped composite. Detailed structural investigations revealed the effective influence of Li4(NH2)3BH4 in different reactions: the irreversible dehydrogenation in the presence of MgH2 and the reversible hydrogen release when it reacts with Li2Mg2(NH)3. The role of Li4(NH2)3BH4 in improving the dehydrogenation kinetics is associated with the weakening of the N-H bond and the mobile small ion mass transfer enhancement. Fil: Amica, Guillermina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina Fil: Cova, Federico Hector. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina Fil: Arneodo Larochette, Pierre Paul. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina Fil: Gennari, Fabiana Cristina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The optical emission from the 5d – 4f allowed transition of Pr3+ ions embedded in sol-gel silica is investigated for High Energy Physics applications requiring fast scintillating materials. A complete and detailed characterization of the optical, scintillation and radiation hardness properties of Pr-doped silica is carried out employing different experimental techniques including steady-state and time-resolved photo-luminescence, radio- and thermo-luminescence, scintillation and optical absorption. Optical absorption measurements, performed after X-ray irradiation sequences up to 1 kGy, evidence the formation of radiation-induced absorption bands related to point defects acting as color centers. Spontaneous partial recovery of the radiation-induced defects at room temperature, as well as after thermal treatments, is also disclosed. Particular attention is paid to the comparison between bulk silica, both before and after a melting process, and fibers. The results reveal the presence of a lower concentration of optically active defects in melted glass. Such comparison highlights a role of the fiber drawing in modifying the glass defectiveness, consisting in the occurrence of a structural reorganization of the amorphous network during the process.

The investigation of the characteristic luminescent response of Ce-doped silica fibers exposed to electrons in the 20-200-GeV energy range is reported in this work to explore the feasibility of using silica-based fibers for a simultaneous dual-readout approach. The sol-gel method allows the preparation of either doped or undoped fibers with high aspect ratio and high purity, providing good flexibility and spatial resolution for the realization of a dual-readout detector. The dual Cherenkov and scintillation light emitted by silica-based fibers potentially offers applications in high-energy-physics calorimetry as well as in other fields, such as radiation monitoring in medicine, security, and industrial control. The response of the fibers, embedded in a tungsten-copper absorber block to obtain a spaghetti-like geometry in a high-energy-physics environment, is investigated through a test-beam campaign at the CERN Super Proton Synchrotron facility. The discrimination of Cherenkov and scintillation light is demonstrated and discussed, along with a detailed investigation of the scintillation properties of the material: time-resolved spectroscopy, relative light output, and attenuation length are evaluated. The results presented in this study can pave the way for further material engineering and future applications.

Large Stokes shift fast emitters show a negligible reabsorption of their luminescence, a feature highly desirable for several applications such as fluorescence imaging, solar-light managing, and fabricating sensitive scintillating detectors for medical imaging and high-rate high-energy physics experiments. Here we obtain high efficiency luminescence with significant Stokes shift by exploiting fluorescent conjugated acene building blocks arranged in nanocrystals. Two ligands of equal molecular length and connectivity, yet complementary electronic properties, are co-assembled by zirconium oxy-hydroxy clusters, generating crystalline hetero-ligand metal-organic framework (MOF) nanocrystals. The diffusion of singlet excitons within the MOF and the matching of ligands absorption and emission properties enables an ultrafast activation of the low energy emission in the 100 ps time scale. The hybrid nanocrystals show a fluorescence quantum efficiency of ~60% and a Stokes shift as large as 750 meV (~6000 cm−1), which suppresses the emission reabsorption also in bulk devices. The fabricated prototypal nanocomposite fast scintillator shows benchmark performances which compete with those of some inorganic and organic commercial systems.