High-resolution X-ray Spectrometry Research Articles

Development of a low-noise readout ASIC for Silicon Drift Detectors in high energy resolution X-ray spectrometry

ASIC with a low-noise readout channel for Silicon Drift Detectors in high energy resolution X-ray spectrometry was designed and prototyped in the AMS 350 nm CMOS process via Europractice as a miniASIC. For the analog readout channel tests there was used the detector module SDD-10-130-PTW LTplus-ic (PNDetector GmbH). The measured energy resolution of this module with the designed readout channel: 200 eV (FWHM) at 55Fe, -16 °C, 1 kcps and a peaking time of 8 μs.

Development of Large Bismuth Absorbers for Magnetic Calorimeters Applied to Hard X-ray Spectrometry

Bismuth is an interesting material for magnetic calorimeter absorbers applied to high energy resolution X-ray spectrometry; it has a low specific heat and high atomic number. However, past detector developments with Bi absorbers were confronted with the low thermal conductivity of bismuth that degraded the energy resolution and deformed the detector response function (non-Gaussian energy peak). In the present study, we have investigated the performances of large bulk bismuth absorbers (\(1\times 1\times 0.16\) mm\(^{3}\)) thermally coupled to metallic magnetic sensors. Despite a very good baseline energy resolution, detectors with monolithic bismuth absorbers have degraded FWHM energy resolutions with any type of thermal coupling between the absorber and the sensor tested. In comparison tests with BiCu and BiAg bilayer absorbers demonstrated much better performances.

Development of a WDX-μ-PIXE system for chemical state mapping

In this paper, we have developed a wavelength dispersive X-ray spectrometer microparticle-induced X-ray emission (WDX-[Formula: see text]-PIXE) system combining a microbeam system with high spatial resolution and wavelength dispersive X-ray (WDX) spectrometry with high-energy resolution for chemical state mapping. A Von Hamos geometry was used for the WDX system to achieve higher detection efficiency and energy resolution. The system consists of a curved crystal and a CCD camera. The WDX system was installed in a newly developed microbeam system. The energy resolution of the WDX system was 0.67 eV for [Formula: see text] (1740 eV). [Formula: see text] and [Formula: see text] X-ray spectra from various Si compounds were measured and chemical shifts related to chemical states were clearly observed. The system was applied to the chemical state analysis of clay particles. After elemental mapping of the clay particles using a conventional [Formula: see text]-PIXE system with a Si(Li) detector, particles to be analyzed were selected and analyzed sequentially with the WDX system. [Formula: see text] spectra from clay particles were obtained. The microscopic spatial distribution of elements and chemical state of the clay particles were sequentially measured with high energy and spatial resolution using a microbeam.

Study on the reflectivity properties of spherically bent analyser crystals

Theoretical and experimental studies are presented on properties of spherically bent analyser crystals for high-resolution X-ray spectrometry. A correction to the bent-crystal strain field owing to its finite surface area is derived. The results are used to explain the reflectivity curves and anisotropic properties of Si(660) and Si(553) analysers in near-backscattering geometry. The results from the calculation agree very well with experimental results obtained using an inelastic X-ray scattering synchrotron beamline.

Small scale production of high purity 193mPt by the 192Os(α,ߙ3n)-process

Abstract Some production aspects of the Auger electron emitter 193mPt (T 1/2=4.33 d) through the 192Os(α,ߙ3n)-process were investigated. Relatively thick targets of 99.65% enriched 192Os, prepared by pressing or electrolytic deposition, were irradiated with 40 MeV α-particles for 3 h at a nominal beam current of 1.6 μA. The radioplatinum formed was chemically separated with a yield of 90% and the expensive target material was recovered with a yield of 85%. The radioactivity of 193mPt was determined by high resolution X-ray spectrometry. The radionuclidic purity of 193mPt amounted to 99%, the level of 195mPt and 191Pt impurities being each 0.5%. The batch yield of 193mPt achieved was about 10 MBq with a specific activity of 1 GBq/μg Pt. Both the batch yield and the specific activity could be appreciably increased through improved targetry. A comparison of the cyclotron and reactor production routes of 193mPt shows that the (n,ߙγ) reaction leads to high production yields but the α-particle induced reaction results in a product of higher radionuclidic purity and four orders of magnitude higher specific activity of 193mPt.

Experimental studies and nuclear model calculations on proton induced reactions on manganese up to 45MeV with reference to production of 55Fe, 54Mn and 51Cr

Excitation functions of the reactions (55)Mn(p,n)(55)Fe, (55)Mn(p,x)(54)Mn and (55)Mn(p,x)(51)Cr were measured from their respective thresholds up to 18 MeV in the first case and up to 45 MeV in the latter two cases, using the conventional stacked-foil technique. The radioactivity of (55)Fe was determined via high resolution X-ray spectrometry and of other radionuclides via high resolution γ-ray spectrometry. Nuclear model calculations were performed using the codes ALICE-IPPE, EMPIRE and TALYS. In some cases, good agreement was found between the experimental and theoretical data while in others considerable deviations were observed. From the experimental data the expected integral yields of the three investigated radionuclides were calculated.

Cross section measurements of the 131Xe(p,n) reaction for production of the therapeutic radionuclide 131Cs

131Cs is an X-ray emitter radioisotope gaining interest in prostate brachytherapy. It is generally produced via the 130Ba(n,γ) 131Ba→ 131Cs process in thermal-flux reactors. Here we investigate its cyclotron production possibilities. Excitation function of the 131Xe(p,n) 131Cs reaction was measured up to 35 MeV using the stacked gascell technique and high-resolution X-ray spectrometry. The experimental data were compared with results of the ALICE-IPPE and EMPIRE-II codes and curves taken from the PADF and TENDL database. The calculated integral yield was 17 MBq/μA h in the energy range E p =20→7 MeV. Comparison of cyclotron and reactor production routes was given.

Measurement of excitation functions of helion-induced reactions on enriched Ru targets for production of medically important 103Pd and 101mRh and some other radionuclides

Excitation functions were determined by the stacked-foil and induced radioactivity measurement technique for the reactions 100Ru( α,n) 103Pd, 101Ru( α,2n) 103Pd, 101Ru( 3He,n) 103Pd, and 102Ru( 3He,2n) 103Pd, producing the therapeutic radionuclide 103Pd, and for the reactions 101Ru( 3He,x) 101mRh(Cum) and 102Ru( 3He,x) 101mRh(Cum), producing the medically interesting radionuclide 101mRh. Data were also measured for the reactions 101Ru( 3He,pn+d) 102m,gRh, 102Ru( 3He,p2n+dn+t) 102m,gRh, 101Ru( 3He,x) 101gRh(Cum), 102Ru( 3He,x) 101gRh(Cum), 101Ru( 3He,3n) 101Pd, 102Ru( 3He,4n) 101Pd, 101Ru( 3He,4n) 100Pd, and 101Ru( 3He,p3n+d2n+tn) 100Rh, producing other palladium and rhodium isotopes/isomers. The energy ranges covered were up to 25 MeV for α-particles and up to 34 MeV for 3He ions. The radioactivity of the radionuclide 103Pd induced in thin metallic foils of the enriched ruthenium isotopes was measured by high-resolution X-ray spectrometry and the radioactivities of other radionuclides by γ-ray spectrometry. The integral thick target yields of the radionuclide 103Pd calculated from the excitation functions of the first four of the above-named reactions amount to 960, 1050, 50, and 725 kBq/μAh, respectively, at the maximum investigated energies of the incident particles. The integral thick target yields of the radionuclide 101mRh amount to 16.1 and 2.9 MBq/μAh for 101Ru and 102Ru targets, respectively, at 34 MeV energy of incident 3He ions. The integral yields of the other observed radionuclides were also deduced from the excitation functions of the above-mentioned respective nuclear reactions. The excitation functions and integral yields of some rare reaction products were also determined. The experimental excitation functions of some reactions are compared with the predictions of nuclear model calculations. In general, good agreement was obtained.

DETECTING STERILE DARK MATTER IN SPACE

Space-based instruments provide new and, in some cases, unique opportunities to search for dark matter. In particular, if dark matter comprises sterile neutrinos, the X-ray detection of their decay line is the most promising strategy for discovery. Sterile neutrinos with masses in the keV range could solve several long-standing astrophysical puzzles, from supernova asymmetries and the pulsar kicks to star formation, reionization, and baryogenesis. The best current limits on sterile neutrinos come from Chandra and XMM-Newton. Future advances can be achieved with a high-resolution X-ray spectrometry in space.

The spectral response of superconducting tunnel junction X-ray detectors

The Advanced Detector Group at LLNL is developing superconducting Nb–Al–AlOx–Al–Nb tunnel junction detector arrays for high-resolution soft X-ray spectrometry. We have characterized the detector response function in the energy range between 50 and 2000 eV with monochromatic X-rays, in collaboration with the Physikalisch-Technische Bundesanstalt Laboratory at the BESSY II electron storage ring. The detectors have an energy resolution between 7 and 15 eV FWHM in that energy range, and a count rate capability of ∼10,000 counts/s per detector pixel. In addition, the detector response function exhibits several spectral artifacts, and although their magnitude is only on the order of 1% of the main line, they can reduce the sensitivity for X-ray analysis of dilute specimens if they overlap with the correspondingly weak emission lines. We have characterized these artifacts by scanning a collimated synchrotron radiation beam across the detector area. We identify their origin due to X-ray absorption at locations other than the main Nb absorber film, and outline future detector designs to reduce the artifacts and thereby extend the spectrometer sensitivity.

Influence of hydrogenation on the microstructure and crystallization of Zr-Cu-Ni-Al-Y metallic glass

Zr-Cu-Ni-Al-Y metallic glass was electrochemically charged with hydrogen. The hydrogen content in the hydrogenated specimen was derived from the shift of scattering maxima of the X-ray diffraction (XRD) spectra. The microstructures of the untreated Zr-Cu-Ni-Al-Y metallic glass and the hydrogenated specimen have been studied using conventional transmission electron microscopy, high-resolution transmission electron microscopy and energy-dispersive X-ray spectrometry as well as XRD. The untreated Zr-Cu-Ni-Al-Y specimen was found to be almost totally amorphous with a trace amount of yttrium oxide. The addition of the rare-earth element yttrium is beneficial for decreasing the oxygen content in the matrix. Some nanosized precipitates have been found in the hydrogenated specimens. The crystallization of the precipitates was found to consist of two stages. The Zr(Cu, Ni, Al, Y) precipitates segregate in the first stage, while the formation of crystalline ZrH2 dominates the second stage. The size, amount and distribution of the nanocrystals are mainly related to the charging current and time.

Devitrification Mechanisms in Al-Y-Ni Glasses

ABSTRACTCrystallization of gas atomized Al-Y-Ni alloy powder during consolidation has been studied ex-situ using high-resolution lattice imaging, diffraction and energy-dispersive X-ray spectrometry experiments in a transmission electron microscope. In the as-atomized powder amorphous particles occur but others show some evidence of decomposition. On the application of heat and pressure two types of decomposition product are formed initially; equiaxed nanoscale α-Al grains embedded in an amorphous matrix, and dendritic aluminum structures with veins of amorphous and micro-crystalline phases between the aluminum-rich regions. Complex ordered structures were identified in the α-Al: thin sheets of solute rich material were formed on the {100} and {110} aluminum planes with ordered cubic symmetry. Precursors for the Al19Ni5Y3 and Al3Y phases are formed in the vein regions. The second and third stages of crystallization involve the conversion of these ordered phases and embryonic precipitates to the better-known binary and ternary compounds.

Measurements and nuclear model calculations on proton-induced reactions on 103Rh up to 40 MeV: evaluation of the excitation function of the 103Rh(p,n) 103Pd reaction relevant to the production of the therapeutic radionuclide 103Pd

Excitation functions were measured by the stacked-foil technique for the reactions 103Rh(p,n) 103Pd, 103Rh(p,3n) 101Pd and 103Rh(p,4n) 100Pd from their respective thresholds up to 39.6 MeV. The radioactivity of the activation products was determined by high-resolution X-ray and γ-ray spectrometry. Statistical model calculations taking into account the precompound effects were performed for all reactions, and good agreement was found with our data. A critical evaluation of the existing and present data for the 103Rh(p,n) 103Pd reaction was carried out. Recommended cross sections and integral yields for this reaction of key importance in the production of the widely used therapeutic radionuclide 103Pd are given.

Gas proportional scintillation counters with a CsI-covered microstrip plate UV photosensor for high-resolution X-ray spectrometry

A xenon-filled gas proportional scintillation counter for X-ray spectrometry is described. The detector uses a microstrip plate covered with a thin CsI film as a photosensor rather than the usual photomultiplier tube. The achieved energy resolution for 5.9 keV X-rays is 12% when the microstrip is operated within the xenon volume and 10.5% when the microstrip is operated in a P-10 environment, separated from the xenon volume by a quartz window.

High-resolution x-ray spectrometry using iridium-gold phase transition thermometers

Cryogenic detectors based on iridium-gold phase transition thermometers are being developed for various applications in astroparticle physics, aiming at high energy resolution, low energy threshold and moderate count rates. A microcalorimeter with an energy resolution of 15.5 eV (FWHM) for the 55 Mn Kα 1 x-ray line for tentative use in an analytical x-ray system (e.g. SEM, TRFA) is presented.

Semiconductor drift detectors: applications and new devices

Recent technological developments and new topology designs have made semiconductor drift detectors ideal devices for high-resolution x-ray spectrometry. In this paper the basic topology of a semiconductor drift detector with on-chip electronics specially designed for x-ray spectrometry is reviewed. These devices have been used for the first time in x-ray and γ-ray spectroscopy applications. In particular, the results obtained in non-destructive analyses by using a EDXRF spectrometer based on a Peltier cooled semiconductor drift detector and in photodetection of scintillation light are reported. The working principle and the first experimental results for a novel position-sensitive x-ray detector with spectroscopic capability are presented. Copyright © 1999 John Wiley & Sons, Ltd.

Correlation between the reliability of laser diodes and the crystal perfection of epitaxial layers estimated by high-resolution x-ray diffractometry

The dependence of the degradation of high-power quantum-well GaAs/AlGaAs laser diodes, grown by molecular-beam epitaxy, on the crystal perfection of the individual layers of the heterostructure is investigated. The crystal perfection of the layers is estimated by highresolution x-ray spectrometry. A numerical fit of the diffraction-reflection curves is performed using the Debye-Waller static factor. It is shown that considerably higher crystal perfection of laser heterostructures can be obtained by using as the waveguide layers binary AlAs/GaAs superlattices instead of the solid solution AlGaAs.

Materials in nanopipes of undoped GaN

The nanopipes in undoped GaN epilayers grown on sapphire substrates were investigated by field emission high-resolution electron microscopy (HREM) and energy-dispersive x-ray spectrometry (EDS). In the HREM images, the cores of the nanopipes appeared disordered in the thin regions and more ordered in the thicker regions, indicating the amorphous layer on the surface has a significant influence on the visible image of the nanopipe in the thin regions. The EDS spectra showed that composition of the materials in nanopipes was mainly oxygen, carbon, and gallium elements. The results suggest that the nanopipes are related to impurities.

The Canadian experience in performing accuracy checks on administered doses of radiopharmaceuticals

A calibration service was introduced in 1986 to assist the Canadian nuclear medicine community in determining more accurately the amount of radioactive material administered to patients for either diagnostic or therapeutic purposes. This aspect of a quality assurance program in nuclear medicine provides an accuracy check on instruments and the technologists using them. The calibration report issued constitutes direct traceability of a facility to a national standards laboratory. Nuclides most frequently calibrated are 99mTc and 131I. Others include 67Ga, 111In, 123I, 125I and 201Tl. All samples received are analysed for radionuclidic impurities by high-resolution X-ray and gamma-ray spectrometry. Ten years of testing has shown that, except for a few conscientious departments, accuracy checks on radionuclide (dose) calibrators are not a high priority. There are 285 nuclear medicine facilities in Canada and, since there is no legal requirement that the calibrators be checked for accuracy, only 29 have had their instruments checked using this service. Of these, 14 perform annual accuracy checks with NRCC. In this paper, the results of the intercomparisons are described, and quality control problems associated with the use of radionuclide calibrators in nuclear medicine are discussed.

Extracting Low Energy X-Ray Peaks From EDS and WDS Spectra

Interest in electron beam x-ray microanalysis with low incident beam energies, defined arbitrarily as 5 keV and below, has been greatly stimulated in recent years by the development of the high performance field emission gun scanning electron microscope (FEG-SEM), which can produce a nanometer-scale probe with sufficient current to operate with both energy dispersive (EDS) and wavelength dispersive (WDS) spectrometers. Microanalysis in this regime requires the analyst to confront new spectrometry problems that are not typically encountered, or that can be safely ignored, when operating with conventional beam energies, 10 keV or greater. With low energy operation, the choice of atomic shells that can be accessed is restricted, forcing the analyst to make use of shells that have low fluorescence yields for intermediate and high atomic number elements, and possibly strong chemical effects, which are evident with high resolution x-ray spectrometry.