0000000000009098
AUTHOR
J.l. Ferrero
Identification of overglaze and underglaze cobalt decoration of ceramics from Valencia(Spain) by portable EDXRF spectrometry
The purpose of this work is the application of non-destructive analysis to differentiate underglaze and overglaze techniques used in the decoration of glazed ceramics from Valencia (Spain). This study was carried out by portable EDXRF spectrometry using an X-ray tube and a thermoelectrically cooled semiconductor detector. From the EDXRF spectra we have identified the main elements present in the tin-opacified lead glaze and in the cobalt pigments. The identification of the underglaze and overglaze decoration is based on the different ratios between the fluorescence line of the main component of the glaze (Pb-La line) and the fluorescence lines of the main components of the pigment (Co-Ka, M…
<title>Studies of the activation background in CsI(Tl) detectors</title>
CsI scintillation crystals are widely used as detection in (gamma) -ray astronomy observations. In the MeV energy region, one of the most important background sources in CsI is the (beta) decays induced in the crystal by cosmic ray protons and their secondaries. One recent idea for reducing this background is to use discrete detector arrays to reject the large amount of localized (beta) decay events. Two experiments were carried out with 1 cm3 CsI crystals bombarded with energetic proton beams and fast/thermal neutrons, with the aim of evaluating the effectiveness of this method in pixelated (1 cm3) CsI detectors. The ratio of the number of decays resulting in single site and multiple site …
X-ray fluorescence analysis of yellow pigments in altarpieces by Valencian artists of the XV and XVI centuries
Abstract XRF analysis has allowed a quick and precise detection and identification of the inorganic elements that compose the yellow pigments in altarpieces of the XV and XVI centuries painted by the Valencian artists Miguel Alcaniz, Vicente Macip, Juan de Juanes, Hernando Yanez de la Almedina and Hernando Llanos. The analyses have been carried out with an XRF portable system that consists of a tube of X-rays and detectors of Si(Li) and cadmium zinc telluride. This system has enabled a non-aggressive and non-destructive analysis of many pieces at the Museo de Bellas Artes of Valencia (Spain). Among the yellow pigments we have identified a pigment composed by lead and tin oxides named lead–t…
Monte Carlo simulation of alpha spectra in low-geometry measurements
Abstract Monte Carlo simulation of alpha spectra obtained with semiconductor detectors in low-geometry has been developed. The proposed method reproduces adequately experimental spectra of alpha emitters by taking into account the energy losses and trajectory changes of alpha particles as consequences of their interactions in the source, backing and detector.
A study of coupled-reaction channel effects in the36S +37Cl system, hybridization between single particle orbits
Elastic and inelastic scattering as well as transfer transitions involving a valence proton in thesd- andfp- shell orbits are studied in the interaction of37Cl +36S at ECM=50 MeV. Experimental angular distributions of single particle states of37Cl (elastic and inelastic transfer) are presented with a CRC analysis. In the CRC calculations the effects of inelastic and transfer couplings are studied using known spectroscopic information. In the CRC analysis six single particle bound states and the collective 2+ excitation of36S are included in the coupling scheme. Higher order coupling effects are found to be important. A distinct effect, the mixing of single particle states (of different pari…
Influence of inelastic couplings on 32S + 24MG sub-barrier fusion
Elastic, inelastic and mutual excitation angular distributions have been measured for 32S+ 24Mg at 65, 75, 56.3, 95 and 110 MeV of 32S incident energy. The data have been analysed by optical model and coupled channel calculations. Energy-dependent optical potentials have been obtained which have been used to describe the 32S + 24Mg fusion data of Berkowitz et al2). Barrier penetration and coupled channel models are compared. It is found that the energy-dependence of the empirical potentials is essential if a consistent simultaneous description of elastic, inelastic an fusion data is required.
Energy dependence of the $^{28}$Si($^{32}$S,$^{36}$Ar)$^{24}$Mg reaction between 90 and 103 MeV incident energy
Abstract Angular distributions for the 28 Si( 32 S, 36 Ar) 24 Mg reaction have been measured from 90 to 103 MeV of incident lab energy, in steps of 0.5 MeV. The ground state, the 2 1 + level in each nucleus and the mutual excitation of both 2 1 + states have been resolved. The data have been analysed in the frame of finite range DWBA calculations. The deduced relative spectroscopic factors show good agreement with those predicted by the model of Chung and Wildenthal but are smaller than those deduced in other experiments.
Characterization of cobalt pigments found in traditional Valencian ceramics by means of laser ablation-inductively coupled plasma mass spectrometry and portable X-ray fluorescence spectrometry.
Abstract In this work, a comparison of the performances of laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) and portable X-ray fluorescence (XRF) spectrometry for the characterization of cobalt blue pigments used in the decoration of Valencian ceramics is presented. Qualitative data on the elemental composition of the blue pigments obtained using both techniques show a good agreement. Moreover, the results clearly illustrate that potters utilized different kinds of cobalt pigments in different historical periods. While both techniques seem suitable for the proposed task, they show different strengths and weaknesses. Portable X-ray fluorescence spectrometry is a cheaper…
Comparison of total-reflection X-ray fluorescence, static and portable energy dispersive X-ray fluorescence spectrometers for art and archeometry studies
Abstract In this paper, a Total-reflection X-ray Fluorescence (TXRF), a static and a portable Energy Dispersive X-ray Fluorescence (EDXRF) spectrometers are described. Both the equipments and the techniques employed in the field of the art and archeometry are compared. Some applications in this area are presented as well. The aim of the work is to know which spectrometer is the best suited depending on the work of art and the problem treated. The conclusion reached from the experience is that the portable EDXRF spectrometer is advisable to make “in situ” and online analysis in a multidisciplinary environment, the static EDXRF equipment is good to perform analysis on paper and metal pieces a…
Hybridization ofsd- andfp-shell proton orbitals in the systemS36+37Cl
Experimental and theoretical evidence is presented that the proton exchange is strongly enhanced by a mixing of single-particle configurations in $^{37}\mathrm{Cl}$ (in the system $^{36}\mathrm{S}$${+}^{37}$Cl, which is shown to be the clearest example of hybridization in nuclear physics. The experimental data on elastic and inelastic transfer are only reproduced if the complete set of single-particle states (${\mathit{d}}_{3/2}$,${\mathit{s}}_{1/2}$,${\mathit{f}}_{7/2}$,${\mathit{p}}_{3/2}$,${\mathit{f}}_{5/2}$, and ${\mathit{p}}_{1/2}$) is included in a coupled-reaction-channel calculation. The strong enhancement is explained by the hybridization of orbits of different parity. In a two-ce…
Study of the background on a ZnS(Ag) alpha counter with a plastic veto detector
Alpha counters based on the scintillation of ZnS(Ag) have been used widely to measure total alpha activity in environmental samples. The main difficulties for this kind of detectors consist of having a reasonable low background, i.e., around 10−3 counts/s. It is assumed that the background comes from natural sources (mainly radon) and there is no contribution from cosmic, beta or gamma rays since the efficiency for these sources is extremely low. However, the study of the background using a thin plastic veto detector shows that the cosmic ray contribution to the alpha background is about 5–50%, whereas the estimated gamma contribution is below 10%. Therefore, this anti-coincidence set-up ca…
Joaquin Sorolla's pigment characterisation of the paintings ‘Vision of Spain’ by means of EDXRF portable system
In this work, portable energy dispersive X-ray fluorescence (EDXRF) spectrometry was employed to the characterisation of the palette used by the Spanish artist Joaquin Sorolla (1863–1923) in the paintings ‘Vision of Spain’, a set of 14 oils on canvas painted by Sorolla between 1911 and 1919 by order of Mr Archer Huntington to decorate the library of the Hispanic Society of America (HSA) in New York. The analyses, sponsored by BANCAJA and provided by the HSA, were carried out in situ, prior to the cleaning and restoration process, while the paintings hanging on the walls of the library of the HSA. The results revealed that the paintings were made over different priming layers containing, res…
One-nucleon transfer reactions induced by 32S on 34S AT Einc = 90.0 and 97.09 MeV
Abstract The one-proton and one-neutron transfer reactions in the interaction of 34 S with incident 32 S were studied in the 0–3.5 MeV excitation energy range of the exit nuclei. The experimental set-up (kinematic identification technique, implanted targets, etc.) has allowed an angular resolution of 0.2°, a mass resolution of 1.5% and a Q -value resolution of 0.35 MeV. Comparison with DWBA computations using an analytical approximation for the radial integral, with insertion of suitable recoil corrections, demonstrates the absorptive direct mechanisms of the reactions, even when double excitation of residual nuclei is present. The extracted values for the products of spectroscopic factors …
Isotopic Effects and Surface Absorption in $^{35-37}$Cl+$^{24}$Mg Interactions
Abstract The few-nucleon transfer is found to play an important role in the isotopic effects observed in absorption. This conclusion is obtained by measuring elastic scattering and quasielastic reactions and by analysing elastic data with both phenomenological and microscopic models. The sensitivity domain is found to be different for imaginary and real potentials. The implication for the validity of the dispersion relation for phenomenological potentials at the real sensitivity radius, when transfers are important, is discussed.
Analysis of pigments from Spanish works of art using a portable EDXRF spectrometer
Nowadays there is an intensive program for the conservation, restoration and analysis of the impressive and extensive Spanish cultural heritage. In the last few years, the Unidad de Arqueometria of the ICMUV has carry out a great quantity of in situ EDXRF analysis of pigments on materials of historic and cultural interest (altarpieces, frescoes, canvas, sculptures, etc.) from museums and churches of the whole of the Spanish geography. Here we present a few examples of the analysis of works of art using x-ray fluorescence spectrometry with a portable system based on x-ray tubes and a non-cryogenic Si-PIN detector. EDXRF qualitative and non-destructive analyses of stone, pigments and preparat…
Energy damping and intermediate-velocity fragment emission in peripheral Kr+Au collisions at 43 MeV/u
Abstract Triple and four-fold coincidences among fragments have been measured in the reaction 84 Kr+Au at 43 MeV/u. All events showing the projectile-like nucleus and fission fragments of the target-like nucleus, and all events with one additional intermediate-velocity fragment, were analysed in the frame of a dissipative collision and a participant-spectator model. The mechanism is basically that of a dissipative collision but the emission of the intermediate velocity fragment by the target differs from an equilibrated evaporation.
Radioactivity measurements on migrating birds (Turdus philomelos) captured in the Comunidad Valenciana (Spain)
The radionuclides 137Cs, 134Cs and 90Sr have been measured in edible tissues and bones of migratory birds (song-thrushes, Turdus philomelos) from central and northern Europe and captured in the Comunidad Valenciana, Spain in the 1994 autumn–winter season. Eight years after the Chernobyl accident, extensive agricultural lands in Europe are still contaminated and this study shows that there was a transfer of radioactive isotopes to the captured migratory song-thrushes. The whole-body dose commitment to humans consuming these birds is estimated.
Applications of the X-ray fluorescence analysis to the cultural patrimony of the Comunidad Valenciana (Spain): Painting, metal and paper
We present examples of the application of the X-ray fluorescence (XRF) to the study of the artistic and cultural patrimony of the Comunidad Valenciana in the following areas: a) Valencian paintings of the XV and XVI centuries; b) silver ornaments coming from Iberian towns (s. III b.C.); c) ink and paper samples in manuscripts and engravings of the XVII and XIX centuries. The non destructive analyses are carried out “in situ” using a XRF system that consists of a tube of X-rays of 50 kV and 1 mA, and a detector of Si(Li) with an energy resolution 140 eV (FWHM at 5.9 keV).
Elastic scattering of 35Cl and 37Cl on 24Mg
Abstract Elastic scattering of 35Cl and 37Cl on 24Mg was measured at two c.m. energies. Optical model analysis with different potentials are compared. Isotopics effects on absorption are observed. The closure approximation model is found to give a good reproduction of experimental data.
Positron lifetime measurements on neutron‐irradiated InP crystals
Neutron‐irradiated InP single crystals have been investigated by positron‐lifetime measurements. The samples were irradiated with thermal neutrons at different fluences yielding concentrations for Sn‐transmuted atoms between 2×1015 and 2×1018 cm−3. The lifetime spectra have been analyzed into one exponential decay component. The mean lifetimes show a monotonous increase with the irradiation dose from 246 to 282 ps. The increase in the lifetime has been associated to a defect containing an Indium vacancy. Thermal annealing at 550 °C reduces the lifetime until values closed to those obtained for the as‐grown and conventionally doped InP crystals. navarrof@evalvx.ific.uv.es ; Jose.Ferrero@uv.es