Quantification of cross-irradiation and cross-illumination using a Risø TL/OSL DA-15 reader

The automated Risø TL/OSL DA-15 reader is widely used for luminescence dating applications. The nature of the device is such that the irradiation and illumination of a sample during the OSL procedures may affect discs in adjacent positions. It is critical to confirm that these factors do not introduce significant systematic errors. The effects of such cross-talk (cross-irradiation and cross-bleaching) are examined and quantified, both for specific and general cases. Depending upon the protocol used, cross-irradiation and cross-bleaching could accumulate to have an effect on the D_e estimate, and for the latter this could be significant (i.e. 10%).     

Nanostructured layers of anion-defective gamma–alumina – New perspective TL and OSL materials for skin dosimetry. Preliminary results

Thin- layer material based on nanostructured Al₂O₃ of the surface density 5 mg/cm² was obtained. The material is characterized by high OSL and TL yields comparable with those for TLD-500 which is one of the leaders among the TL and OSL detectors. The dose response, fading and dependence of TL yield on heating rate was studied. It is established that high luminescence yield of the samples under study correlates with the content of anion vacancies and γ-phase of Al₂O₃. The data for time-resolved luminescent spectroscopy are presented, which evidence for possible correlation between high TL and OSL activity and the F-type centers. It is noted that the material needs to be modified for successful use in dosimetry. In addition further studies to decrease the contribution of unstable (at 300 К) components to OSL and TL yields are required.     

Equation of state for technetium from X‐ray diffraction and first-principle calculations

The ambient temperature equation of state (EoS) of technetium metal has been measured by X-ray diffraction. The metal was compressed using a diamond anvil cell and using a 4:1 methanol-ethanol pressure transmitting medium. The maximum pressure achieved, as determined from the gold pressureEquation of state for technetium from X-ray diffraction and first-principle calculations scale, was 67 GPa. The compression data shows that the HCP phase of technetium is stable up to 67 GPa. The compression curve of technetium was also calculated using first-principles total-energy calculations. Utilizing a number of fitting strategies to compare the experimental and theoretical data it is determined that the Vinet equation of state with an ambient isothermal bulk modulus of B_0T=288 GPa and a first pressure derivative of B′=5.9(2) best represent the compression behavior of technetium metal.     

Effect of gamma and beta radiation on I–V characterization of the solar cell panel

ABSTRACT

Optoelectronic devices, widely used in high energy and nuclear physics applications, suffer severe radiation damage that leads to degradations in its efficiency. In this paper, the influence of gamma radiation (¹³⁷Ce source) and beta radiation (⁹⁰Sr source) on the photoelectric parameters of the Si solar cell, based on the I–V characterization at different irradiation exposer, has been studied. The penetrating radiation produces defects in the base material, may be activated during its lifetime, becoming traps for electron–hole pairs produced optically and, this will, decrease the efficiency of the solar cell. The main objective of the paper is to study and measure changes in the I–V characteristics of solar cells, such as efficiency, maximum current, maximum power, and efficiency, due to the exposure of solar systems to different doses of γ and β irradiations.     

Estimating the fraction of gamma quanta in the primary cosmic ray flux with energies of ∼1017 eV from the MSU EAS array data

Using data from the MSU EAS array and model calculations, we search for events with abnormally small fractions of muons with energies above 10 GeV in showers with particle numbers of >2 × 10⁷ and zenith angles of <30 degrees. We confirm with good statistical accuracy that the content of gamma quanta in the primary cosmic ray flux can be as high as 2% at energies of ～10¹⁷ eV.     

Effect of inductive and capacitive coupling on the current–voltage characteristic and electromagnetic radiation from a system of Josephson junctions

We have studied the current–voltage characteristic of a system of long Josephson junctions taking into account the inductive and capacitive coupling. The dependence of the average time derivative of the phase difference on the bias current and spatiotemporal dependences of the phase difference and magnetic field in each junction are considered. The possibility of branching of the current–voltage characteristic in the region of zero field step, which is associated with different numbers of fluxons in individual Josephson junctions, is demonstrated. The current–voltage characteristic of the system of Josephson junctions is compared with the case of a single junction, and it is shown that the observed branching is due to coupling between the junctions. The intensity of electromagnetic radiation associated with motion of fluxons is calculated, and the effect of coupling between junctions on the radiation power is analyzed.     

Performance of a 3 mm×3 mm silicon photomultiplier for use on the X-ray calibration system of the SVOM gamma ray monitor

The calibration detector of a gamma ray monitor (GRM) is designed to detect alpha particles from ²⁴¹Am and to send out the coincidence signal to the GRM X-ray detector. The silicon photomultiplier (SiPM), as a novel photon device, is a good candidate to convert alpha-exciting fluorescent photons into electric signals. Three types of SiPMs from SSPM and MPPC, each having an active area of 3 mm×3 mm, were compared in the matter of the spectra from low-intensity light, dark count, crosstalk probability and I-V curve. The temperature coe cient of SSPM-0710G9MM was also characterized. The application of a SiPM on the GRM has been proved to be feasible.     

Performance of a 3 mm×3 mm silicon photomultiplier for use on the X-ray calibration system of the SVOM gamma ray monitor

The calibration detector of a gamma ray monitor (GRM) is designed to detect alpha particles from ²⁴¹Am and to send out the coincidence signal to the GRM X-ray detector. The silicon photomultiplier (SiPM), as a novel photon device, is a good candidate to convert alpha-exciting fluorescent photons into electric signals. Three types of SiPMs from SSPM and MPPC, each having an active area of 3 mm×3 mm, were compared in the matter of the spectra from low-intensity light, dark count, crosstalk probability and I-V curve. The temperature coe cient of SSPM-0710G9MM was also characterized. The application of a SiPM on the GRM has been proved to be feasible.     

Relationship between width of pulses and Lorentz factor expected from the light curve of fireball sources

Time profiles of many gamma-ray bursts consist of distinct pulses, which provides a possibility of characterizing the temporal structure of these bursts. We employ a simple model of highly symmetric fireballs to analyse the effect of the expansion speed on the light curve arising from different forms of local pulses. The relationship between the ratio r of the FWHM width of the rising phase of the light curve to that of the decaying phase and the Lorentz factor is investigated. The analysis shows that, when the rest frame radiation form is ignored, temporal profiles of the light curve arising from pulses of fireballs will not be affected by the expansion speed （that is, r is almost a constant） as long as the fireball expands relativistically. When the rest frame radiation form is taken into account, there will be a break in the curves of r - log F. The location of the break depends mainly on the adopted value of the rest frame peak frequency VO,p. One would reach almost the same result when a jet is considered. In addition, we utilize a sample of 48 individual GRB pulses to check the relationship between the ratio r and the expansion speed F. We find no significant correlation between them, and this is consistent with the theoretical analysis.     

Cosmic ray “knee” in the spectrum and proton-proton cross section from the point of view of new quarks

A possible explanation of the “knee” in the cosmic ray spectrum by the change in hadron-hadron interactions at the corresponding energy is discussed. It is shown that, at c.m. energies above 5 TeV, the total proton-proton cross sections obtained from cosmic ray experiments exceed the asymptotic fit made over the collider data. Such a rise of the cross sections favors the hypothesis about new chromodynamically charged degrees of freedom, the threshold of their creation being about \(\sqrt {^\mathcal{S} knee} \approx 2.3 TeV\). The properties of these new particles which are needed are discussed.     

Perturbation of the spectrum of the Ba atom by radiation from a color center laser in the range from 8400 to 8700 cm−1

The perturbation of the Ba atom by radiation from a color center laser in the range between 8400 and 8700 cm^?1 is experimentally studied. The study was performed by the method of resonance ionization spectroscopy by simultaneously irradiating a beam of Ba atoms by a color center laser and a dye laser at 17735 cm^?1. The dynamic polarizabilities of the 5d6p ¹ F ₀ ³ and 6p ^{2 1} D ₂ levels are measured.     

Beijing synchrotron radiation total—reflection X—ray fluorescence analysis facility and its applications on trace element study of cells

The feasibility of total-reflection X-ray fluorescence(TXRF) analysis excited by synchrotron radiation applied to trace element analysis of biological cells is investigated.The Beijing synchrotron radiation TXRF facility and the related xperimental method are also described.The elemental mininum detection limits of some standard reference materials are determined.The elemental compositions of a cluster of small intestine cells of a small white mouse are given,and hence the average trace element contents of the single small intestine cell are also obtained.With this technique,the changes of some trace elements in the cells of lung and cervix cancer before and after apoptosis are also preliminarily studied.2001 Elsevier Science B.V.All rights Reserved.     

Study of strain and compostion of the self—organized GE dots by grazing incident X—ray diffraction

Grazing incident X-ray diffraction at different grazing angles for self-organized Ge dots grown on Si(001) are carried out and lattice constant expansions of 1.2?parallel to the surface as compared with the Si lattice are found within the Ge dots.A 3.1?lattice expansion of the Ge dots along the growth direction is also fund by ordinary X-ray(004) diffraction.According to the Poisson equation and the Vegard law,our results infer that the Ge dot should be a partially strain relaxed SiGe alloy with Ge content of abuot 55?2001 Elsevier Science B.V.All rights reserved.     

Nonlinear coupling between the mean polarizability \bar \gamma of molecules and the local-field anisotropy in a liquid crystal and change of the “ \bar \gamma = const” paradigm

The nonlinear relation between the mean effective polarizability $ \bar \gamma $ of molecules and the local-field anisotropy in uniaxial liquid crystals is demonstrated. Stringent constraints on $ \bar \gamma $ from below, indicative of the dependence of $ \bar \gamma $ on the liquid-crystal state and the change of the “ $ \bar \gamma $ = const” paradigm, are established. The theoretical results are confirmed by experiments with nematic liquid crystals having high and low birefringences.     

Variation of internal stresses as a function of deformation and distance from sources in Cu–Al polycrystalline alloys

Internal stress fields in deformed Cu–Al polycrystalline alloys are studied via TEM. The sources of such stresses are determined. Internal stress fields are measured as a function of distance from different sources. The effect grain size has on the formation of internal stresses is determined.     

Application of Synchrotron X‐Ray Microbeam Spectroscopy to the Determination of Metal Distribution and Speciation in Biological Tissues

Abstract

Resolving the distribution and speciation of metal(loid)s within biological environmental samples is essential for understanding bioavailability, trophic transfer, and environmental risk. We used synchrotron x‐ray microspectroscopy to analyze a range of samples that had been exposed to metal(loid) contamination. Microprobe x‐ray fluorescence elemental mapping (µSXRF) of decomposing rhizosphere microcosms consisting of Ni‐ and U‐contaminated soil planted with wheat (Triticum aestivum) showed the change in Ni and U distribution over a 27‐day period, with a progressive movement of U into decaying tissue. µSXRF maps showed the micrometer‐scale distribution of Ca, Mn, Fe, Ni, and U in roots of willow (Salix nigra L.) growing on a former radiological settling pond, with U located outside of the epidermis and Ni inside the cortex. X‐ray computed tomography (CMT) of woody tissue of this same affected willow showed that small points of high Ni fluorescence observed previously are actually a Ni‐rich substance contained within an individual xylem vessel. µSXRF and x‐ray absorption near‐edge spectroscopy (XANES) linked the elevated Se concentrations in sediments of a coal fly ash settling pond with oral deformities of bullfrog tadpoles (Rana catesbeiana). Se distribution was localized within the deformed mouthparts, and with an oxidation state of Se (?II) consistent with organo‐Se compounds, it suggests oral deformities are caused by incorporation of Se into proteins. The range of tissues analyzed in this study highlight the applicability of synchrotron X‐ray microspectroscopic techniques to biological tissues and the study of metal(loid) bioavailability.     

Mössbauer, magnetic, X‐ray fluorescence and transmission electron microscopy study of natural magnetic materials from speleothems: haematite and the Morin transition

Detrital magnetic materials within cave stalagmitic formations, e.g., haematite or magnetite, carry remanence whose vector is of value in dating. Magnetometry measurements on a particular haematite‐bearing sample reveal that remanence was substantially restored and/or conserved on rewarming after cooling below the Morin transition temperature. Mössbauer measurements indicate the presence of two types of haematite, distinguished primarily by particle size. The majority is small in size, partially exhibiting superparamagnetism, and does not undergo a Morin transition above liquid nitrogen temperature. Superparamagnetic goethite is the second major component. Mine haematite samples of surface location with different color and mineralogical composition have also been studied. Possible relations between the mineralogical composition of the mine samples and detrital stalagmitic magnetic material, the modifications and the origin of this mineralization are discussed. Special attention is paid to the “irreversible” Morin transition in large enough (>20 nm) haematite particles and the possible loss of natural remanent magnetization and hence of palaeomagnetic records.