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The historical development of the thermoelectrically cooled X‐ray detector and its impact on the portable and hand‐held XRF industries (February 2009)
Abstract
Portable/hand-held X-ray fluorescence (XRF) instruments now achieve performance comparable to laboratory-sized, expensive, liquid nitrogen cooled systems. The availability of these systems has expanded XRF applications out of the laboratory to in situ analysis including that for lead in paint, alloy identification, process control, restriction of hazardous substances/waste from electrical and electronic equipment (RoHS/WEEE) compliance, and art and archaeology. The development of small, low-power, high-performance, and cost-effective X-ray detectors was a critical part of this transformation. This paper will look back at the development and technical achievements of the Amptek X-ray detector as well the future direction of portable XRF. Copyright © 2009 John Wiley & Sons, Ltd.
... However, their relative energy resolution is usually limited to > 2% and may be much poorer. 2 While diagnostic analyses which rely on atomic line emission of x-rays are well suited by crystal spectrometers, analyses which rely on broad-spectrum emission, such as Bremsstrahlung, are better suited by pulse-height detectors. Furthermore, while line-emission analyses are restricted to a finite set of N degrees-of-freedom, specifically line positions, intensities, and FWHMs, from which to draw ≤ N parameters about the target ions, i.e., temperatures, densities, and velocities, broad-spectrum analyses have a 1-D continuous degree-of-freedom from which a 1-D continuous parameter such as an energy distribution function may be drawn about the incident electrons. ...
... In pulse-height x-ray detectors, resolution is limited by the counting statistics of the number of electron-hole pairs which are produced by the incident x-ray. 2 Thus, the response of the detector to a monoenergetic beam of x-rays is a mostly-Gaussian distribution of energies centered on the correct energy. This response function can be made into a response matrix when the response functions to many different energies are concatenated as the columns of a matrix. ...
We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV.
... However, their relative energy resolution is usually limited to > 2% and may be much poorer. 2 While diagnostic analyses which rely on atomic line emission of x-rays are well suited by crystal spectrometers, analyses which rely on broad-spectrum emission, such as Bremsstrahlung, are better suited by pulse-height detectors. Furthermore, while line-emission analyses are restricted to a finite set of N degrees-of-freedom, specifically line positions, intensities, and FWHMs, from which to draw ≤ N parameters about the target ions, i.e., temperatures, densities, and velocities, broad-spectrum analyses have a 1-D continuous degree-of-freedom from which a 1-D continuous parameter such as an energy distribution function may be drawn about the incident electrons. ...
... In pulse-height x-ray detectors, resolution is limited by the counting statistics of the number of electron-hole pairs which are produced by the incident x-ray. 2 Thus, the response of the detector to a monoenergetic beam of x-rays is a mostly-Gaussian distribution of energies centered on the correct energy. This response function can be made into a response matrix when the response functions to many different energies are concatenated as the columns of a matrix. ...
We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV.
... [32], [33]. For low energy X-rays, the electronic noise in the CZT detection system is critical, being the most important factor that determines the energy resolution and the energy detection limit. ...
... Although the spectroscopic response of Si-PIN detectors [22], [33] be better due to the slightly better energy resolution, its intrinsic detection efficiency is lower for X-rays within the keV range when compared with CZT detectors ( ). For instance, for a typical Si thickness within m range, the intrinsic detection efficiency at 22 keV is as low as , respectively [22]. ...
In the present study, we show that CZT detectors can be used in a wide X-ray energy range including low-energy X-rays down to 2.1 keV at which may be extended down to 1.5 keV by additional cooling to . CZT detector was operated in the low energy X-ray band to detect the K fluorescence X-rays emitted by low-Z elements, such as Ca, K, Cl, S, and eventually even further P, Si, Al. Additionally, it was demonstrated the fine spectroscopic features of the CZT detector cooled to , which make it suitable for the detection of L fluorescence X-rays emitted by high-Z elements in the range, such as Th, Pa, U, Np and Pu, resulting from the decay of actinide radionuclides , , and , respectively. With this cooled CZT detector it was possible to resolve the main L X-ray lines as well as to measure its intensity. The relative intensity obtained for the Pu L X-ray lines , , , , , and was, respectively, , , , , and . The Np L X-ray most intense lines , , , and yielded a relative intensity of , , and , respectively. The overall results are in good agreement with the values found in literature. The principal performance features of the CZT detector were, also studied experimentally or estimated from data tabulated in the literature. Notably, we found a -fold diminution of the electronic noise FWHM temperature sensitivity (from
... XR-100CR is a high performance X-ray detector mounted on a thermo-electric cooler (Peltier type) together with the input FET to the pre-amplifier. These components are kept at À55°C and are enclosed in a hermetic package with a Beryllium window [8]. It can be operated in air or in vacuum with a 149 eV FWHM resolution at 5.9 keV. ...
... 4 shows the measured photon energy spectra of the USX beam, at accelerating voltages ranging from 2 to 3 kV, as measured using a semiconductor detector (Si-PIN photodiode). The measurement is performed at 5 cm from the aluminium foil and at very low tube current (0.5 mA) as it is recommended to operate the detector at low photon fluence rate [8]. ...
... Это находит применение в случае рентгенофлуоресцентного определения некоторых элементов в отдельных включениях геологических образцов при изучении проблемы генезиса угля. Динамичное развитие характерно для детекторов с термоэлектрическим охлаждением [8,[10][11][12], варианта РФА с полным внешним отражением (РФА ПВО, TXRF) [8,[13][14][15][16]. При исследовании разнообразных материалов в полевых условиях широко применяются удобные портативные энергодисперсионные рентгенофлуоресцентные спектрометры [8,12,[17][18][19]. ...
В представленном обзоре кратко рассмотрены достижения в разработке аппаратуры для проведения рентгенофлуоресцентного анализа (РФА), способы подготовки проб, взаимные влияния элементов, а также приведены примеры применения РФА для определения элементного состава углей и зол различного происхождения. Отдельное внимание уделено варианту РФА с полным внешним отражением.
... Finally an Amptek XR-100CR high performance X-ray detector [14], utilizing a Silicon PIN photodiode, is installed in the focal plane to monitor the stability of the beam. Table 5 describes a number of characteristics of the four detectors. ...
The Nuclear Spectroscopic Telescope ARray (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (5-80 keV) telescope to orbit. The ground calibration of the optics posed a challenge as the need to suppress finite source distance effects over the full optic and the energy range of interest were unique requirements not met by any existing facility. In this paper we present the requirements for the NuSTAR optics ground calibration, and how the Rainwater Memorial Calibration Facility, RaMCaF, is designed to meet the calibration requirements. The nearly 175 m long beamline sports a 48 cm diameter 5-100 keV X-ray beam and is capable of carrying out detailed studies of large diameter optic elements, such as the NuSTAR optics, as well as flat multilayer-coated Silicon wafers.
... The second revolution happened at the beginning of the nineties with the development, around 1990-1995, of highresolution small size, Peltier cooled HgI 2 detectors (developed by Jan Iwanczyk and coworkers) (Fig. 8) [11], and, soon after, Peltier-cooled Si-PIN detectors (developed by John Pantazis and coworkers at AMPTEK) ( Fig. 9) [12,13]. These detectors had an energy resolution comparable to that of nitrogen-cooled Si detectors and allowed to assemble the first portable devices to carry out measurements [15,16]. ...
This paper describes history and technical evolution of portable devices which use energy-dispersive X-ray fluorescence (EDXRF)-analysis to study works of art. The history starts in 1971, when the first transportable equipment was employed to examine the pigments of Raphael’s painting “La Deposizione” during restoration at the “Istituto Centrale del Restauro” in Rome. Then, paintings of all types were analyzed and metals (bronzes, brasses, gold and silver). The evolution of the exciting source is described (from radioisotopes or big size X-ray tubes, to miniaturized, dedicated X-ray tubes) and of X-ray detectors (from proportional gas counters, to N2-cooled Si or Ge-detectors, to Peltier cooled HgI2 and Si-PIN, to Peltier cooled Si-drift). Also, the pulse height analyzers had an important evolution, from a heavy box to a computer card, to very small electronic circuits included in the detector box. The most “modern” portable EDXRF device is currently composed of a small-size X-ray tube, a Si-drift detector, both properly collimated, a portable computer, and dedicated software for the processing of the data. The total weight of such a device is about 2 kg. The last evolution: from analysis of a limited number of points to a complete scanning of the artifact. A mechanics is also required, with a sophisticated software interfacing mechanics to measuring heads. Maps giving the distribution of all analyzed elements in all areas of the painting “La Fornarina” by Raphael could be obtained. Finally, an accurate analysis of the K or L-X rays of the elements present in the paintings allowed to determine the disposition of the pigment in the correct layer.
... Energy resolutions close to the theoretically achievable energy resolution limited by the Fano ionization statistics (= 119 eV Full Width at Half Maximum, FWHM, at 5.9 keV) have been achieved when the detectors are operated at low temperatures (≤ 20 • C); e.g. FWHM at 5.9 keV of 130 eV with Si (Li) at −173 • C [1], of 149 eV with Si p + -i-n + photodiodes at −43 • C [2], of 130 eV with CCDs at −90 • C [3], of 133 eV with SDDs at 10 • C [4], and of 131 eV with DEPFETs at room temperature [5]. ...
A commercial-off-the-shelf (COTS) Si p+-i-n+ photodiode (Hamamatsu S5973), designed for visible and infrared detection, was repurposed for use as a low-cost and readily available detector for photon counting X-ray and γ-ray spectroscopy. The detector was investigated for its spectroscopic performance, while being coupled to a custom-made charge sensitive preamplifier, under the illumination of photons with energies up to 59.54 keV. The detector-preamplifier system was subjected to temperatures from 80 °C to 20 °C. Energy resolutions (Full Width at Half Maximum, FWHM) of 0.66 keV ± 0.05 keV at 5.9 keV, 0.70 keV ± 0.04 keV at 22.16 keV, and 0.74 keV ± 0.06 keV at 59.54 keV, were achieved at 20 °C. The energy resolution deteriorated at 80 °C, reaching a value of 1.8 keV ± 0.1 keV FWHM at 59.54 keV. The results suggested that the performance, in terms of energy resolution, of the currently reported COTS Si detector was better than that achieved with certain purpose-grown wide bandgap detectors at 20 °C and 40 °C and better than that achieved with other repurposed Si detectors at 20°C, opening new possibilities for applications for the Hamamatsu S5973 detectors and increasing the availability of low cost X-ray and γ-ray spectroscopy instrumentation.
... Despite the compatibility of RXRFS instrumentation with the concept of portability, the decay of the source over time, and regulatory issues related to the use of radioactive material, were major disadvantages. The advent of miniaturized X-ray tubes and cooled Si-PiN diode detectors (Pantazis et al. 2010) was a breakthrough (see Chapter 18, Volume 1), and a new generation of instrumentation was developed, eliminating isotope sources while also providing superior levels of sensitivity and LOD. These newer-generation instruments are well-suited for screening a variety of raw materials and food products (Potts and West 2008). ...
This chapter critically discusses the state-of-the-art application of portable (i.e. transportable, field-portable, or fieldable, including briefcase-like, handheld, and miniaturized) spectroscopic and spectrometric instrumentation in food, feed, and agriculture sectors. The overview is focused on the current employment of X-ray fluorescence (XRF), laser-induced breakdown spectroscopy (LIBS), nuclear magnetic resonance (NMR), and mass spectrometry (MS). However, brief comparisons with other popular techniques (e.g. FT-IR, NIR, Raman) are provided, particularly in cases where either of them exhibits distinct advantages or profound limitations in this field of research. Merits and pitfalls of these techniques are exposed. This chapter describes that, in general, the capability for on-site, rapid chemical/elemental analysis, with minimally invasive measurements and optimization by untrained personnel, deliver outstanding value of particular importance for the analysis of food, feed, and agriculture items. These advantageous properties lead to the widespread implementation of portable instrumentations throughout this field. This chapter aims to present the information to the readers in a critical and interpretative manner; therefore, restrictions in the current applicability of these techniques, as well as challenges yet to be addressed, are highlighted. These considerations are based on the most recent literature pertaining to the highest development level at the time. Furthermore, the literature overview is supplemented by the interpretation of the current development trends as well as future prospects of transportable spectroscopy and spectrometry in the field of food, feed, and agriculture.
... Despite the compatibility of RXRFS instrumentation with the concept of portability, the decay of the source over time, and regulatory issues related to the use of radioactive material, were major disadvantages. The advent of miniaturized X-ray tubes and cooled Si-PiN diode detectors (Pantazis et al. 2010) was a breakthrough (see Chapter 18, Volume 1), and a new generation of instrumentation was developed, eliminating isotope sources while also providing superior levels of sensitivity and LOD. These newer-generation instruments are well-suited for screening a variety of raw materials and food products (Potts and West 2008). ...
Spectroscopic methods of qualitative and quantitative analysis have profound practical importance in food and agriculture. There exist subtle differences among the problems typically encountered in analytical routines between these two sectors, but the advantages of the methodologies described in this chapter are equally meaningful in both fields. Analytical tasks in food science and technology, regardless of whether the food industry, governmental agencies, or academic laboratories are considered, are expected to determine food composition and characteristics to ensure the quality and safety of the food supply. It is mandatory by legal regulations to perform analysis of food products throughout the production process, from raw material to the final product after its delivery to the market. This includes the chemical composition and physical properties of food items. The result of the analysis should be sufficient to determine the nutritional value of the product, its functional characteristics, and market acceptability. The specific nature of the food supply chain puts particular importance on the rapidness, precision, and robustness of the analysis. The prominence of the method’s reliability ensured through proper validation is stressed. Through these lenses, conventional methods for determining food chemical and physical properties become hardly suitable for the needs of the modern global market. The traditional approaches of analytical chemistry are time-consuming, and what is critical is mostly limited to laboratory use. The quality
data from items analyzed in food and agriculture are typically obtained through time-consuming, inflexible, and destructive (wet chemical) conventional methods. These conventional methods do not meet today’s requirements for rapid, on-site, analytical methods. In contrast, spectroscopic and spectrometric methods are capable of high-throughput yet low sample volume, rapid, often non- or minimally-invasive analysis, and, in certain cases, remote measurement as well. Furthermore, as it will be emphasized in this chapter, the challenges met in the food and agriculture areas imply a particular set of advantages for the application of portable spectroscopy and spectrometry.
... The history of portable XRF analyzers was summarized in a 2012 symposium; 57 it started with an isotope-source lead paint analyzer in the early 1990s, followed by alloy analyzers in the mid-1990s, and later converting over almost exclusively to instruments using miniature X-ray tube sources. Key enabling technologies were the development of thermoelectrically cooled silicon PIN-diode (p-type-intrinsicn-type) detectors 58 and miniature X-ray tubes. 59 Subsequently, handheld XRF applications have expanded to the whole food chain or life cycle, 60 of the metals from mineral exploration through mining and refining, to alloy identification in fabrication, finished goods, in situ inspection, and in scrap metal recycling. ...
Until very recently, handheld spectrometers were the domain of major analytical and security instrument companies, with turnkey analyzers using spectroscopic techniques from X-ray fluorescence (XRF) for elemental analysis (metals), to Raman, mid-infrared, and near-infrared (NIR) for molecular analysis (mostly organics). However, the past few years have seen rapid changes in this landscape with the introduction of handheld laser-induced breakdown spectroscopy (LIBS), smartphone spectroscopy focusing on medical diagnostics for low-resource areas, commercial engines that a variety of companies can build up into products, hyphenated or dual technology instruments, low-cost visible-shortwave NIR instruments selling directly to the public, and, most recently, portable hyperspectral imaging instruments. Successful handheld instruments are designed to give answers to non-scientist operators; therefore, their developers have put extensive resources into reliable identification algorithms, spectroscopic libraries or databases, and qualitative and quantitative calibrations. As spectroscopic instruments become smaller and lower cost, “engines” have emerged, leading to the possibility of being incorporated in consumer devices and smart appliances, part of the Internet of Things (IOT). This review outlines the technologies used in portable spectroscopy, discusses their applications, both qualitative and quantitative, and how instrument developers and vendors have approached giving actionable answers to non-scientists. It outlines concerns on crowdsourced data, especially for heterogeneous samples, and finally looks towards the future in areas like IOT, emerging technologies for instruments, and portable hyphenated and hyperspectral instruments.
... The main characteristics of these tubes are air cooling, low weight and high stability. On the other hand, several types of non-cryogenic, miniaturized detectors are in constant improvement [5]. There are, of course, several degrees of portability, ranging from the equipment used by Čechác et al. [6] with an annular radionuclide source and a Si(Li) detector cooled with liquid nitrogen, to the ultra-compact, handheld commercial equipments, such as the one used by Pincé et al. [7]. ...
The X-ray fluorescence technique is a powerful analytical tool with a broad range of applications such as quality control, environmental contamination by heavy metals, cultural heritage, among others. For the first time, a portable energy dispersive X-ray fluorescence spectrometer was assembled, with orthogonal triaxial geometry between the X-ray tube, the secondary target, the sample and the detector. This geometry reduces the background of the measured spectra by reducing significantly the Bremsstrahlung produced in the tube through polarization in the secondary target and in the sample. Consequently, a practically monochromatic excitation energy is obtained. In this way, a better peak-background ratio is obtained compared to similar devices, improving the detection limits and leading to superior sensitivity. The performance of this setup is compared with the one of a benchtop setup with triaxial geometry and a portable setup with planar geometry. Two case studies are presented concerning the analysis of a 18th century paper document, and the bone remains of an individual buried in the early 19th century.
... Fixed XRF instruments have tradition of many decades, but XRF method can be implemented in portable devices also [84], [85] [86]. The flexibility of portable XRF spectrometers has been greatly improved by means of the development of compact, air-cooled X-ray tubes and thermoelectrically cooled X-ray detectors [87]. Radioisotope X-ray sources can be replaced by aircooled miniature X-ray tubes in portable devices with considerable improvements to the portability of XRF spectrometers, because the administrative restrictions concerning radioisotope handling are avoided, indeed, the spread of low-power Xray tube makes possible the instrument safely use without external shielding. ...
A new integrated system capable of simultaneously performing EDXRF (Energy Dispersive X-Ray Fluorescence), and Raman analyses is described. The new system has been designed in the frame of the IT@CHA project funded by the Italian Ministry for Education and Research in order to be a compact and portable instrument. This system will combine the information about elemental composition obtainable by XRF with the molecular information obtainable by Raman technique. The results of preliminary performance evaluation are also presented.
... X-ray spectra have been recorded using a semiconductor Peltier cooled detector of the type AMTEK, Model XR-100CR (Si-PIN photodiode) coupled to a digital pulse processor PX4. The detector crystal (300 mm thickness, 2.4 Â 2.8 mm active area) is mounted inside the vacuum enclosure provided with a beryllium window (Pantazis et al., 2010). For Ultrasoft X-rays the photon transmission through the beryllium window (12.5 mm thickness) varies with energy which will in turn impact the amplitude of the measured spectrum. ...
Ultrasoft X-ray characteristic aluminum K alpha line (Al Kα with energy of 1.5 keV) is used in radiobiological experiments to study the effect of radiation on biological matter. A simple method to generate a continuous beam of those X-ray radiations is to bombarding an aluminum target with accelerated electrons using high voltage (HV). In this work, by varying the HV we study the characteristics of a photon beam generated by means of a cold cathode transmission X-ray tube. The anode is a thin (16µm) aluminum foil supported by a copper grid. The spatial distribution of air kerma is measured using gafchromic films of HD-810 calibrated with a parallel plate free-air ionization chamber. We show that HV strongly modifies the energetic spectrum and air kerma rate as well as its uniformity and intensity in air.
... XRF analyses by means of modern portable systems produce analytical results of high accuracy consistent with standard or specific calibrations, with results from traditional laboratory XRF systems, and with elemental concentrations measured in acidic solutions. This is documented by numerous studies on sediments, soils, artifacts and other materials ( Laohaudomchock et al. 2010, Pantazis 2010, Weindorf et al. 2010, Zhu and Weindorf 2010). Geochronological information was obtained by means of radiocarbon dating of plant remains and biogenetically produced carbonate as well as by archaeological age estimation of diagnostic sherds found embedded in vibracore sediments. ...
It is well known from historic catalogues that the Greek coast has repeatedly been struck by large earthquakes and associated tsunami events during the past millennia. The seismically highly active Hellenic Arc, where the African plate is being subducted by the Aegean microplate, is considered to be the most significant tsunami source in the wider region. The study presented in this paper focuses on sedimentary and geomorphological tsunami traces encountered at Pheia, western Peloponnese (Greece), one of the harbours of the nearby cult site Olympia. Sedimentological, pedological, geoarchaeological and geochemical analyses revealed tsunami sand and gravel of mostly marine origin reaching far inland. Wave refraction and channeling effects seem to have steepened tsunami waters up to 18-20 m above present sea level and induced tsunami water passage across the narrow Katakolo Pass into adjacent coastal plains. Tsunami deposits that were accumulated onshore were partly cemented and later exposed in the form of beachrock. By radiocarbon dating and archaeological age estimation of ceramic fragments, three distinct tsunami events were found, namely for the 6(th) millennium BC, for the time around 4300 +/- 200 cal BC and for the Byzantine to post-Byzantine period. Olympia's harbour site Pheia was finally destroyed by tsunami landfall, most probably in the 6(th) century AD and accompanied by co-seismic submergence.
... The design is a novel electron multiplying CCD (EMCCD) which is coupled to a thin microcolumnar scintillator film (CsI (Tl)) via a fiber optic taper. Finally an Amptek XR-100CR high performance X-ray detector [14], utilizing a Silicon PIN photodiode, is installed in the focal plane to monitor the stability of the beam.Table 5 describes a number of characteristics of the four detectors. ...
The Nuclear Spectroscopic Telescope ARray (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (5–80 keV) telescope to orbit. The ground calibration of the optics posed a challenge as the need to suppress finite source distance effects over the full optic and the energy range of interest were unique requirements not met by any existing facility. In this paper we present the requirements for the NuSTAR optics ground calibration, and how the Rainwater Memorial Calibration Facility, RaMCaF, is designed to meet the calibration requirements. The nearly 175 m long beamline sports a 48 cm diameter 5– 100 keV X-ray beam and is capable of carrying out detailed studies of large diameter optic elements, such as the NuSTAR optics, as well as flat multilayer-coated Silicon wafers.
... With the help of computers, deconvolution methods were developed to extract the net intensities of overlapping individual X-rays lines (Beckhoff et al. 2006). An XRF device was even included on the Apollo 15 and 16 missions (LearnXRF 2011) and Mars Pathfinder mission in 1996(Pantazis et al. 2010. While in 1970s the XRF spectrometry applications in environmental sciences demonstrated some amateurism, by the end of the 20th century the mentioned applications were the most published X-ray analysis results in the scientific literature. ...
Information about the elemental compositions of coal and coal ash is very important to solve some issues related to both technological processes and the control of environmental pollution. It is known that the coal and coal ash samples often contain significant amounts of valuable as well as toxic components (e.g., V, Cr, Со, Ni, Cu, Zn, As, Sr, Ba, Pb, Ga, and Ge) that can be successfully determined by X‐ray fluorescence (XRF) spectrometry. This review briefly discusses the development of XRF equipment, elements of interest determined by XRF, and common sample preparation procedures. The calculation of relative intensities of analytical lines of some elements and scattered radiation is presented to demonstrate possible matrix effects in XRF analysis. Possibilities and drawbacks of total reflection XRF (TXRF) are described in detail as the coal and ash analysis is a relatively new area of application of TXRF method. The review also presents examples of the application of the XRF method for analysis of waste from coal preparation plants and thermal power plants to assess their prospects and to choose a method for extracting individual elements. Among the reviewed publications, several works are devoted to the study of the element distributions, especially rare earth elements, in coals, coal ash, and coal waste.
This paper describes history and evolution of portable devices which use energy-dispersive X-ray fluorescence (EDXRF)-analysis to study pigments in paintings of all type and over all kinds of substrate (canvas, wood, copper, ceramics, paper, plaster….) and ancient metals (bronzes, brasses, gold, silver…) The history starts in 1971, when the first transportable equipment was employed to examine the pigments of Raphael painting “La Deposizione” during restoration. The paper continues then examining the evolution of the exciting sources (from radioisotopes to big size X-ray tubes, to miniaturized, dedicated X-ray tubes) , of X-ray detectors (from proportional gas counters, to N2 -cooled Si or Ge-detectors, to Peltier cooled HgI2 and Si-PIN, to Peltier cooled Si-drift). Also the pulse height analyzers had an important evolution, from heavy boxes to boards, to small size boxes to very small electronic circuits included in the detector container. Also equipment with single-channel analyzers were employed at the beginning.
The most “modern” EDXRF device is currently composed of a small size X-ray tube and a Si-drift detector, both properly collimated, and a dedicated PC. The total weight of the device is of about 2 Kg.
Finally , the last evolution and revolution: from analysis of a limited number of points to a complete scanning of the painting. A mechanics is required, with a sophisticated software interfacing mechanics to measuring head. Maps giving the distribution of all analyzed elements in all areas of the painting may be obtained.
We describe a method to reduce vacuum ultraviolet (VUV) pulse pileup (PPU) in x-ray pulse-height Silicon Drift Detector (SDD) signals. An Amptek FAST SDD, with C1 (Si 3 N 4 ) window, measures bremsstrahlung emitted from PFRC-2 plasma to extract the electron temperature (T e ) and density (n e ). The C1 window has low transmissivity for photons with energy below 200 eV though will transmit some VUV and soft x-ray photons, which PFRC-2 plasmas abundantly emit. Multi-VUV-photon PPU contaminates the interpretation of x rays with energy [Formula: see text] 100 eV, particularly in a low-energy exponential tail. The predicted low transmissivity of ∼1 μm thick Mylar [polyethylene terephthalate (PET)] to photons of energy [Formula: see text] eV led to the selection of Mylar as the candidate filter to reduce VUV PPU. Experiments were conducted on an x-ray tube with a graphite target and on a quasi-Maxwellian tenuous plasma (n e ∼ 10 ⁹ cm ⁻³ ) with effective temperatures reaching 1500 eV. A Mylar filter thickness of 850 nm is consistent with the results. The Mylar-filter-equipped SDD was then used on the PFRC-2 plasma, showing a substantial reduction in the low-energy x-ray signal, supporting our hypothesis of the importance of VUV PPU. We describe the modeling and experiments performed to characterize the effect of the Mylar filter on SDD measurements.
Hand-held X-ray fluorescence (XRF) instrumentation has become widely used in a broad range of applications for problem solving. When used for in situ measurements (that is, instrumentation placed in contact...
Stainless steel is a very important technological material used in various industries. In this work, a simple non-destructive method is developed for major as well as trace elemental determination in stainless steel samples using micro-X-ray fluorescence (XRF) based technique. The utilization of full bremsstrahlung excitation in combination with micro-focused geometry substantially reduces the detection limit of different elements present in stainless steel. The developed methodology is capable of determining elemental concentrations down to 30–80 ppm level in stainless steel matrix without any requirement of cumbersome dissolution or separation procedure. Elements such as Si, P, S and Co were determined simultaneously at trace level using the developed micro-XRF based technique. At the same time this technique is also capable of analyzing elements which are present at percentage levels. Till now there is no such report showing the capability of lab-XRF based non-destructive technique for the analysis of both major as well trace elements down to such low concentration level to the best of our knowledge. Moreover, the methodology involved is very simple and straight forward. The analytical results obtained were very much satisfactory with good accuracy and precision.
Determination of trace elemental concentrations in presence of heavy Z matrix like uranium using X-Ray Fluorescence (XRF) based technique require separation of major matrix from the sample matrix. This separation process is laborious and also produces large amount of organic waste. To counter this problem we have developed a Micro-XRF based technique for the trace elemental analysis in uranium matrix without applying any matrix separation steps. The main challenge of trace elemental analysis in presence of heavy matrix like uranium is severe matrix effect which deteriorates the detection limit as well as the analytical result. In order to assess the matrix tolerance for the direct trace elemental analysis in uranium by X-Ray Fluorescence technique, a detailed study has been conducted to observe the effect of uranium matrix on the analytical results like detection limits or recovery rate etc in the present paper. Based on the detail studies, a limiting concentration for uranium as major matrix has been optimized, up to which matrix effect can be tolerable for trace elemental analysis without further matrix separation. However if the matrix concentration goes beyond that limit, the sample has to be diluted to maintain the uranium matrix concentration below that limit. The presently developed methodology has been validated by determining trace elemental concentration in real natural uranium samples down to few hundred ng/mL concentration level. The presently developed methodology is very simple, cost-effective and less time consuming, with detection limits comparable to other well established trace analytical methods. Moreover the presently developed methodology is having an added advantage of avoiding the complex matrix separation steps up to a certain level of matrix concentration.
In this work, an energy-resolving thermoelectrically cooled single crystal cadmium telluride (CdTe) detector system upgraded with the latest firmware was optimized for high X-ray flux operations using high bias voltage and fast peaking time. This detector system was deployed into an experimental benchtop X-ray fluorescence (XRF) imaging/computed tomography (XFCT) system developed for quantitative imaging of metal nanoprobes such as gold nanoparticles (GNPs). Using the firmware-upgraded and existing/old CdTe detector systems, the Compton/XRF spectra from small (8 mm diameter) GNP-containing phantoms were acquired. The phantoms were irradiated with 1.8 mm Sn-filtered 125 kVp cone beam X-rays at 24 mA. The firmware-upgraded detector system produced relatively lower dead time under high X-ray flux, compared with the old detector system, and performed well with the spectral resolution of ∼0.7 keV (in full width at half maximum) at 69 keV photon energy. Given the same 2 mm aperture detector collimator and irradiation time of 10 s, this detector system managed to score nearly 50% more gold XRF signals than the existing one at all GNP concentrations tested. This improvement resulted in the GNP detection limit of 0.02 wt. % which was lower than that (0.03 wt. %) achievable with the existing detector system. When combined with the detector collimator containing a larger (3 mm) aperture, the firmware-upgraded detector system produced drastically more gold XRF signal at a given GNP concentration (e.g., 9 times more for 1 wt. % GNP solution and irradiation time of 10 s), leading to further reduction in the GNP detection limit (i.e., 0.01 wt. %). The present investigation showed that the firmware upgraded CdTe detector system optimized for high X-ray flux operations allowed for better photon counting efficiency, thus leading to sensitivity enhancement of an experimental benchtop XRF/XFCT imaging system.
Commercially available fully spectroscopic pixelated cadmium telluride (CdTe) detector systems have been adopted lately for benchtop x-ray fluorescence (XRF) imaging/computed tomography (XFCT) of objects containing metal nanoprobes such as gold nanoparticles (GNPs). To date, however, some important characteristics of such detector systems under typical operating conditions of benchtop XRF/XFCT imaging systems are not well known. One important but poorly studied characteristic is the effect of detector bias-voltage on photon counting efficiency, energy resolution, and the resulting material detection limit. In this work, therefore, we investigated these characteristics for a commercial pixelated detector system adopting a 1-mm-thick CdTe sensor (0.25-mm pixel-pitch), known as HEXITEC, incorporated into an experimental benchtop cone-beam XFCT system with parallel-hole detector collimation. The detector system, operated at different bias-voltages, was used to acquire the gold XRF/Compton spectra from 1.0 wt% GNP-loaded phantom irradiated with 125 kVp x-rays filtered by 1.8-mm Tin. At each bias-voltage, the gold XRF signal, and the full-width-at-half-maximum at gold Kα2 XRF peak (∼67 keV) provided photon counting efficiency and energy resolution, respectively. Under the current experimental conditions, the detector photon counting efficiency and energy resolution improved with increasing bias-voltage by ∼41 and ∼29% at −300V; ∼54 and ∼35% at −500V, respectively, when compared to those at −100V. Consequently, the GNP detection limit improved by ∼26% at −300V and ∼30% at −500V. Furthermore, the homogeneity of per-pixel energy resolution within the collimated detector area improved by ∼34% at −300V and ∼54% at −500V. These results suggested the gradual improvements in the detector performance with increasing bias-voltage up to −500V. However, at and beyond −550V, there were no discernible improvements in photon counting efficiency and energy resolution. Thus, the bias-voltage range of −500 to −550V was found optimal under the current experimental conditions that are considered typical of benchtop XRF/XFCT imaging tasks.
In this paper, we described a method of double-sided diffusion and drift of lithium-ions into monocrystalline silicon for the formation of the large-sized, p-i-n structured Si(Li) radiation detectors. The p-i-n structure is a p-n junction with a doped region, where the “i-region” is between the n and the p layers. A well-defined i-region is usually associated with p or n layers with high resistivities. The p-i-n structure is mostly used in diodes and in some types of semiconductor radiation detectors. The uniqueness of this method is that, in this method, the processes of diffusion and drift of lithium-ions, which are the main processes in the formation of Si(Li) p-i-n structures, are produced from both flat sides of cylindrical-shaped monocrystalline silicon, at optimal temperature (T = 420 °C) conditions of diffusion, and subsequently, with synchronous supply of temperature (from 55 to 100 °C) and reverse bias voltage (from 70 to 300 V) during drift of lithium-ions into silicon. Thus, shortening the manufacturing time of the detector and providing a more uniform distribution of lithium-ions in the crystal volume. Since, at present, the development of manufacturing of large-sized Si(Li) detectors is hindered due to difficulties in obtaining a uniformly compensated large area and time-consuming manufacturing process, the proposed method may open up new possibilities in detector manufacturing.
A portable spectrometer should be small, lightweight, and capable of running on battery power for a reasonable duration of time. These instruments are intended for use in the field and, therefore, must perform well outside the climate‐controlled environment of a laboratory. When judged against its laboratory counterpart, a portable spectrometer, evaluated strictly on typical laboratory specifications for analytical performance, usually will not perform as well. For many of the spectroscopic techniques, the availability of portable spectrometers was driven by safety, security, terrorism, and military concerns. The major exceptions to this are handheld X‐ray fluorescence, laser‐induced breakdown spectroscopy, and near‐infrared spectroscopy systems, where field instrumentation has been driven almost exclusively by commercial reasons. Applications are critical for the success of portable spectrometers. This chapter also presents an overview of the key concepts discussed in this book.
Historically, the primary sensors used in energy‐dispersive X‐ray Fluorescence spectrometers were cryogenic cooled Si(Li) detectors. The revolutionary invention of silicon drift detector, made by Emilio Gatti and Pavel Rehak in 1982, gave a new push to the development of semiconductor detectors for x‐ray spectrometry, and provided remarkably better detector performance parameters than Si‐PIN. All of these components, a PIN or SDD detector, cooled with a Peltier cooler, as well as the readout electronics, are small enough to easily fit on a small handheld XRF instrument. This chapter briefly reviews the basic physical principles of semiconductor detectors. There are several fundamental textbooks which detail the relevant aspects of semiconductor detector physics and signal processing. The chapter provides a brief review of the principles behind semiconductor detectors and readout electronics. The Si detectors’ quantum efficiency is determined by absorption of X‐rays in the detector volume.
X-ray fluorescence analysis (XRF) is widely used when determining the concentrations of elements in various materials in biological research. Current review considers the achievements related to the features of the XRF method. X-ray fluorescence analysis in most cases is a non-destructive method that has proven its potential for measuring the concentrations of elements with a high atomic number Z in organs and tissues in vivo. The main areas of its application in biology and medicine are content determination of basic and toxic elements in plants, samples of bones, teeth, hairs, nails and tissues of vital organs, body fluids such as blood, serum, plasma, saliva, urine, etc. Usually, these studies are part of applied programs that include environmental and metabolic analyses of the population, including the influence of professional factors. The advantages of XRF are also discussed with regards to biological materials. It is noted that the form of the element in the sample practically does not affect the analysis result. In recent years, several new XRF spectrometers models have been designed, where polycapillary lenses and half lenses are used as collimating systems. This is important in the case of in vivo application of X-ray fluorescence determination of certain elements in bones and tissues. The dynamic development is typical for detectors with thermoelectric cooling. Variants of preparation of biological materials for analysis are discussed (grinding, dry or wet ashing, acid decomposition, use of suspensions in the case of XRF with TIR). The results of evaluating the interelement effects for XRF of materials of plant origin, including herbs, spices, apple leaves, birch and tomato leaves, tea, wheat, rye, rice, oatmeal, flax flour, beans, ground, and instant coffee are presented. Examples of the use of XRF in various types of forensic research are considered: poisoning, counterfeiting of drugs and food brands, dental implants, identification of remains. The review presents examples of the participation of Russian X-ray physicists in solving the problems under consideration. The list of references is 400 papers, mainly including the publications of the last 20 years.
Cultural Heritage objects are frequently unavailable for transportation to laboratory facilities due to their size, location or local Cultural Heritage preservation regulations. The development of handheld XRF (hXRF) systems has, therefore, proven to be essential in the study of unmovable objects. In this study, two handheld XRF instruments—Bruker™ Tracer III SD® and Olympus™ Innov-X Delta Premium—were compared and evaluated using tesserae from the Mosaico de los Amores (Linares, Spain). Given their portability, the user-friendly nature of their operating systems and their overall performance, both hXRF instruments are highly recommended for in situ campaigns in Cultural Heritage studies. However, the detection limits calculated for each element point towards a better detection of low-Z elements when using the two-beam mode of the Olympus™ Innov-X Delta Premium hXRF. This study underlines the importance of systems that allow the analysis of the same point with analytical conditions optimized for different chemical elements.
A new table-top combined spectrometer was designed and constructed consisting of X-ray fluorescence and Raman spectrometers for spot-analysis of elementary and chemical composition of solid and liquid substances for industrial analytical applications.
Novel confocal X-ray fluorescence (XRF) spectrometer was designed and constructed for 3D analysis of elementary composition in the surface layer of spatially extended objects having unlimited chemical composition and geometrical shape. The main elements of the XRF device were mounted on a moving frame of a commercial 3D printer. The XRF unit consists of a silicon drift detector and a low-power transmission-type X-ray tube. Both the excitation and secondary X-ray beams were formed and regulated by simple collimator systems in order to create a macro confocal measuring setup. The spatial accuracy of the mechanical stages of the 3D printer achieved was less than 5 μm at 100-μm step-size. The diameter of the focal spot of the confocal measuring arrangement was between 1.5 and 2.0 mm. The alignment of the excitation and secondary X-ray beams and the selection of the measuring spot on the sample surface were ensured by two laser beams and a digital microscope for visualization of the irradiated spot. The elements of the optical system together with the XRF spectrometer were mounted on the horizontal arm of the 3D printer, which mechanical design is capable of synchronized moving the full spectroscopic device within vertical directions. Analytical capability and the 3D spatial resolution of the confocal spectrometer were determined. Copyright
Mobile instrumentation is of growing importance to archaeometry research. Equipment is utilized in the field or at museums, thus avoiding transportation or risk of damage to valuable artifacts. Many spectroscopic techniques are nondestructive and micro-destructive in nature, which preserves the cultural heritage objects themselves. This review includes over 160 references pertaining to the use of mobile spectroscopy for archaeometry. Following a discussion of terminology related to mobile instrumental methods, results of a literature survey on their applications for cultural heritage objects is presented. Sections devoted to specific techniques are then provided: Raman spectroscopy, X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, laser-induced breakdown spectroscopy, and less frequently used techniques. The review closes with a discussion of combined instrumental approaches.
This paper presents, for the first time in the Mediterranean, geo-scientific evidence of fan al- luviation and terrace formation by repeated tsunami inundation since the mid-Holocene. Tsunami events revealed to be a dominating factor in the overall landscape evolution of the near-coast zone around the Gulf of Kyparissia. High-resolution multi-proxy palaeoenvironmental analyses were carried out based on vibracores, down to 16 m below surface, drilled along a transect in the Epitalio valley to the SE of the city of Pyrgos. We used sedimentological, micropalaeontological, mineralogical, geochemical and geochro- nological methods in order to detect and evaluate landscape changes. Vibracoring sites were selected after detailed geophysical prospection using electrical resistivity tomography measurements. The Epitalio valley, located approximately 4 km distant from the present coastline and only approximately 800 m long, is characterised by a large triangle-shaped fan. This fan ends at the distinctive step of the Olympia terrace, 5.5 m high, facing towards the lower Alpheios River valley. The prominent and active Alpheios Fault and Epitalio Fault zones directly run across the study area. The Epitalio fan stratigraphy revealed conspicuous coarse-grained layers out of gravel, coarse and medium sand and marine shell debris associated with basal erosional unconformities, fining upward of grain size and incorporated rip-up clasts out of underlying material. These high-energy layers were found repeatedly intersecting silt-dominated fluvio-limnic deposits. Microfossil analyses of high-energy layers revealed the presence of mixed lagoonal, shallow marine and deep water foraminifera, in parts strongly damaged. This allochthonous marine signal goes far beyond the (para-)autochthonous background signal of ubiquitous marine species which come from reworked bedrock units. Further evidence of high-energy impact from the seaside are the strong geomorphological discrepancy between the small Epitalio valley head and the large Epitalio fan together with lithostratigraphical characteristics and dimensions of the high-energy deposits, as well as mineralogical and geochemical fingerprints such as high Ca/Fe and Sr/K ratios. We conclude that the Epitalio valley was repeatedly inundated by tsunami waters across the Epitalio pass accumulating a large amount of tsunami inflow sediments in the form of the Epitalio fan. The Olympia terrace front was formed both during tsunami backflow along the Alpheios River depression line and, later, by Alpheios River floods. Isochronic tsunami signatures are known from several coastal archives in the closer and wider environs of the study area: We found that Epitalio tsunami events T0, T1 and T2 occurred at approximately 5300 – 5200 cal BC, 4350 – 4250 cal BC and during the 3rd millennium BC, respectively, as part of supra-regional tsunami events. Based on the study of reliable relative sea level markers, we detected vertical crust uplift bound to the foot walls of the Pheia, Alpheios and Epitalio Fault Zones in the range of at least 12 –13 m, in some parts even 20 m, during the past 6400 or so years. Tsunami flooding of the Epitalio valley and the formation of the Epitalio fan at least partially thus occurred at times when the elevation of the local topography was minimum 12 –13 m lower. Under such circumstances, the local tsunami hazard was even much higher than today.
This review covers past and present developments of Analytical Chemistry in the field of Cultural Heritage (CH), from the methods to characterize materials to the procedures aiming to diagnose the state of conservation of CH assets. A great number of analytical methodologies and tools (molecular and elemental spectroscopic techniques, chemometrics, chemical reactivity and modeling, etc.) are now available to define: (a) the impacts of the environmental stressors (natural and anthropogenic), (b) the decaying (chemical reactions) pathways of such materials with the surrounding environment, (c) the development of new remediation (cleaning, consolidation, rehabilitation, etc.) processes based on the chemical knowledge and (d) the transfer of such knowledge to Conservation Departments in Museums and companies working in the field of CH. Two important issues are highlighted in this review. One is the important role of the analytical chemistry in this field, although its role was forgotten till few decades in this important area of knowledge; nowadays there are hundreds of papers demonstrating the important role of analytical chemistry practitioners in any kind of CH actions. The other is the societal impact of the issues related to the study of Heritage (i.e, Rock art paintings, Pompeii, the paintings in medieval churches, the masters of painting, etc.) where analytical chemist are important actors specially if portable instruments are used in field works. Finally a special consideration will be paid to future developments and how Analytical Chemistry can give even added value to the research in CH
This paper summarizes an oral presentation of the same title presented at the occasion of recognizing the “The 100th Anniversary of X-ray Spectroscopy” at DXC 2013. It gives an overview of the development in electronics with focus on (mainly) energy-dispersive X-ray detectors and related data processing. Naturally this has its origin in the early transistors and the first semiconductor junction detectors of the late 1940s. It was followed by refinement of semiconductor detector technology in general and particularly by the invention of Li-drifting and employment of low-noise field effect transistors until such devices matured sufficiently to be marketed by the late 1960s. Further improvement followed in resolution, speed, operability at room temperature, and development of junction arrays with imaging capabilities. An important aspect is the development of related software requiring affordable laboratory computers, programming languages, and databases of fundamental parameters. Today x-ray fluorescence analysis (and not only the energy-dispersive variant) is widely employed as an analytical tool for the traditional technical and industrial applications but notably also, at an expanding rate as well as variety, in other fields including environmental, medical, archaeological, space, arts, and many more.
The development of analytical chemistry in the past decades has provided the raw materials industry with a wealth of new methods and procedures for the characterization of raw, intermediate and final products. The greatest advances were made in trace and micro analytical methods. These are now routinely available at reasonable cost and turnaround times. Equally significant for the industry is the development of process analytical methods for bulk properties that provide crucial information for successful automation of complex processes.
Zusammenfassung
Die Entwicklung der analytischen Chemie in den vergangenen Jahrzehnten hat eine Vielzahl neuer Methoden und Verfahren zur Charakterisierung von Rohstoffen, Zwischenprodukten und Handelsware gebracht. Die großen Fortschritte beziehen sich dabei auf neue Methoden der Spuren- und Mikroanalyse, die jetzt routinemäßig zu vernünftigen Preisen bei akzeptablen Analysenzeiten verfügbar sind. Gleichermaßen wichtig für die Industrie ist die Entwicklung prozessanalytischer Methoden für Volumeneigenschaften, die entscheidende Informationen für die erfolgreiche Automation komplexer Prozesse bereitstellen können.
“Small” spectrometers fall into three broad classes: small versions of laboratory instruments, providing data, subsequently processed on a PC; dedicated analyzers, providing actionable information to an individual operator; and process analyzers, providing quantitative or semi-quantitative information to a process controller. The emphasis of this paper is on handheld dedicated analyzers. Many spectrometers have historically been large, possible fragile, expensive and complicated to use. The challenge over the last dozen years, as instruments have moved into the field, has been to make spectrometers smaller, affordable, rugged, easy-to-use, but most of all capable of delivering actionable results. Actionable results can dramatically improve the efficiency of a testing process and transform the way business is done. There are several keys to this handheld spectrometer revolution. Consumer electronics has given us powerful mobile platforms, compact batteries, clearly visible displays, new user interfaces, etc., while telecomm has revolutionized miniature optics, sources and detectors. While these technologies enable miniature spectrometers themselves, actionable information has demanded the development of rugged algorithms for material confirmation, unknown identification, mixture analysis and detection of suspicious materials in unknown matrices. These algorithms are far more sophisticated than the ‘correlation’ or ‘dot-product’ methods commonly used in benchtop instruments. Finally, continuing consumer electronics advances now enable many more technologies to be incorporated into handheld spectrometers, including Bluetooth, wireless, WiFi, GPS, cameras and bar code readers, and the continued size shrinkage of spectrometer ‘engines’ leads to the prospect of dual technology or ‘hyphenated’ handheld instruments.
Field-portable X-ray fluorescence (FP-XRF) instruments are important for non-destructive, rapid and convenient measurements of lead in paint, in view of potential remediation. Using real-life paint samples, we compared measurements from three FP-XRF instruments currently used in Switzerland with laboratory measurements using inductively coupled plasma mass spectrometry after complete sample dissolution. Two FP-XRF devices that functioned by lead L shell excitation frequently underestimated the lead concentration of samples. Lack of accuracy correlated with lead depth and/or the presence of additional metal elements (Zn, Ba or Ti). A radioactive source emitter XRF that enabled the additional K shell excitation showed higher accuracy and precision, regardless of the depth of the lead layer in the sample or the presence of other elements. Inspection of samples by light and electron microscopy revealed the diversity of real-life samples, with multi-layered paints showing various depths of lead and other metals. We conclude that the most accurate measurements of lead in paint are currently obtained with instruments that provide at least sufficient energy for lead K shell excitation.
This review offers the reader a wealth of information published between April 2010 and March 2011 concerning analytical endeavours using the range of conventional and hyphenated XRF techniques that encourage the user to ensure the potential for high spectral sensitivity and, where appropriate, spatial resolution is achieved. The development of advanced micro-beam set ups and new X-ray optics driven by third generation synchrotron based XRF techniques provide nano-imaging and the detection of nano-particles on single cells whilst TXRF coupled with GIXRF and GEXRF offer great potential for non-destructive investigations of thin layers on reflecting surfaces as well as depth profiling of implants. A new portable XRF system is described as an alternative for the traditionally applied K-X-ray fluorescence technology for in vivo measurements of lead in bone. Cryogenic cooling of heat sensitive biological samples is offered as a method to mitigate possible damage by the use of the more powerful μ-XRF technique. Other new preparation methods are also reviewed for the presentation and analysis of industrial, environmental and archaeological samples. One of the more unusual contributions available this year in the characterisation and use of industrial minerals showed that a semi-precious stone, amethyst, is more effective at shielding radiation than concrete.
The James L. Waters Symposium 2012 had five invited speakers to describe the development and commercialization of portable, hand-held X-ray fluorescence (XRF) spectrometers.Lee Grodzins described the birth and the maturation of hand-held XRF (HHXRF) spectrometers.Andrew Ellis described how the stainless-steel industry in Finland led to the development of X-MET HHXRF analyzers.Charles Jensen reviewed the performance improvements in miniature X-ray sources made by his company, Moxtek.Alan Huber explained how his company, Amptek, led the development of detectors for HHXRF.Stanislaw Piorek detailed the evolution of analytical capabilities of field-portable, HHXRF analyzers.
This paper presents evidence of multiple tsunami impact on the Bay of Palairos-Pogonia, NW Greece, during the Holocene based on detailed geo-scientific studies. Altogether, 41 vibracores were drilled to detect high-energy influence in the stratigraphical record. Layers of coarse-grained allochthonous marine deposits were found intersecting autochthonous fine-grained back beach sediments in the Palairos coastal plain, on top of beach or marly bedrock units at Pogonia beach and along the Pogonia cliff section. High-energy deposits are associated with specific sedimentary structures such as fining upward sequences, rip up-clasts, basal erosional contact, bi- to multimodal grain size distribution, lamination, and co-existence of both well rounded and angular, sharply edged components, all of them typical of tsunami impact. Macro- and microfaunal analyses revealed tsunami-related input of numerous ex situ marine species and mostly angular shell debris into quiescent fresh- to brackish water environments by high-energy and long-distance transport. Geophysical methods helped to find subsurface structures and to seize the lateral extent of tsunami layers. Ca–Fe ratios derived from XRF measurements were used to trace tsunami influence inland. Most important is the widespread spatial distribution of the tsunamites with a lateral extent between 70 m at the Pogonia cliff section, 200 m at Pogonia beach, and 1 km in the central Palairos plain, and overall tendencies of fining and thinning towards inland. Highest elevations of tsunamites were found around Pogonia village at ca. 7.5 m a.s.l. Vibracore data give evidence that the overall coastal evolution has been strongly affected, locally even controlled by multiple high-energy impact.
In this work, a study of detection systems in portable X-ray fluorescence (PXRF) spectrometry was performed. An assessment of various detectors and their influence on the measurement of trace elements in different bulk materials, from light to heavy matrices, was done. Four reference materials were analyzed: Orchard Leaves (NBS-1571); Bone Meal (NIST-1486); River Sediment (NBS-1645) and Free-Cutting Brass (NBS-1105). Detection limits were calculated for the elements present in the reference materials, quantitative calculations were performed for three known samples and a comparison was made for each detector. Three case studies were also performed in order to appraise the behavior of the detection systems: A paper document from 1909, a potassium alum/calcite mixture and a Portuguese coin.
Uncritical application of portable X-ray fluorescence (PXRF) to non-destructive analysis of archaeological ceramics has been received with scepticism. In this article, we present a methodological evaluation of the parameters and constraints for PXRF analysis of archaeological ceramics. We use experimental matrices that simulate characteristics of archaeological artefacts to demonstrate the impact of (1) surface morphology, (2) organic surface coatings and (3) grain size and mineralogy on non-destructive PXRF analysis. We then apply these parameters to PXRF analysis of heterogeneous handmade ceramics from central Turkey. We conclude that with appropriate methodology, non-destructive PXRF analysis can be demonstrated to provide a high level of accurate and precise geochemical discrimination for archaeological ceramics. Copyright © 2011 John Wiley & Sons, Ltd.
A new class of silicon drift detectors (SDD), called "Vortex™", with a large active area (~ 0.5 cm2), high-energy resolution (1 Mcps) has been developed for X-ray diffraction (XRD) and X-ray fluorescence (XRF) applications. The Vortex™ design allows for a relatively large active area while still maintaining a very low anode capacitance (~ 60 fF). This very small detector capacitance results in a reduction of the series- noise component and hence a reduction of the overall inherent electronic noise. The Vortex™ detector utilizes novel patent pending structures that have produced very low dark current (both bulk silicon dark current and surface dark current), high electric field, uniform charge collection, low noise and high-sensitivity to low energy X-rays. An energy resolution of 143 eV FWHM was measured at 5.9 keV, 6 µs peaking time; < 250 eV FWHM was achieved at 250 ns with commensurate output count rates of greater than 400 Kcps. The details of the detector performance as a function of amplifier peaking time and input count rates, and as compared to a comparable Si(Li) detector, are discussed.
The paper presents a series of in-situ Energy Dispersive X-ray Fluorescence (EDXRF) measurements performed in Greece and Cyprus for the characterization and quantitative
analysis of valuable archaeological and historical artifacts, such as pigments on wall paintings and ceramics as well as gold
and bronze alloys on sculpture and jewelry. The various types of instrumentation and analytical procedures used for the quantification
of in-situ XRF data will be discussed. The experience acquired from the above investigations will be critically reviewed in order to
assess the importance, as well as the limitations of in-situ EDXRF analyses in the preservation and conservation of our cultural heritage.
Silicon diodes have traditionally been the detectors of choice for quantitative X-ray spectroscopy. Their response has been very well characterized and existing software algorithms process the spectra for accurate, quantitative analysis. But Si diodes have limited sensitivity at energies above 30 keV, while recent regulations require measurement of heavy metals such as lead and mercury, with K X-ray emissions well above 30 keV. Measuring the K lines is advantageous to reduce the interference between the L lines of these elements with each other and with the K lines of light elements. CdTe has much higher stopping power than Si, making it attractive for measuring higher energies, but the quality and reproducibility of its spectra have limited its use in the energy range of characteristic X-rays, <100 keV. CdTe detectors have now been optimized for energies <100 keV, yielding electronic noise of 500 eV for a 5 mm times 5 mm times 0.75 mm device. This provides adequate energy resolution for distinguishing characteristic X-ray peaks >30 keV. The response function of these CdTe detectors differs in important ways from that of Si detectors, requiring changes to the X-ray analytical software used to process the spectra. This paper will characterize the response of the latest generation of high resolution CdTe detectors at the energies of characteristic X-rays. It will present effects important for X-ray analysis, including the peak shape arising from hole tailing, escape peaks, spectral background, linearity, and stability. Finally, this paper will present spectral processing algorithms optimized for CdTe, including peak shape and escape peak algorithms.
A compact, high resolution X-ray and gamma ray spectroscopy system
has recently been developed which provides excellent energy resolution
over a wide range of photon energies. Two detector types have been
tested, a cooled silicon PIN photodiode for X-ray energies from 2keV to
30 keV and a CdTe detector for energies from 20 keV to 1 MeV. The CdTe
detector can be operated cooled or at room temperature. The heart of the
system is a miniature preamplifier developed at AMPTEK which is used in
combination with a small thermoelectric cooler to reduce the leakage
current of the detectors. Using the cooled Si-PIN detector, 660 eV FWHM
was achieved at 5.9 keV and using a CdTe detector 1.3 keV was achieved
at 60 keV both with nearly 100% counting efficiency. Good resolution was
also achieved at higher energies
The recent results on development of X-ray Si(Li), Si-planar and CdTe p-i-n detectors cooled by Peltier coolers for fabrication of laboratory and portable XRF analysers for different applications are discussed.Low detection limits of XRF analysers are provided by increasing of detectors sensitive surface; improvement of their spectrometrical characteristics; decreasing of front-end-electronics noise level; Peltier coolers and vacuum chambers cooling modes optimization.Solution of all mentioned tasks allowed to develop Peltier cooled detectors with the following performances:1.Si(Li) detectors:S=20mm2, thickness=3.5mm, 175eV (5.9keV), 430eV (59.6keV);S=100mm2; thickness=4.5mm, 270eV (5.9keV), 485eV (59.6keV).2.Si-planar detector:S=10mm2, thickness=0.4mm, 230eV (5.9keV), 460eV (59.6keV).3.CdTe p-i-n detectors:S=16mm2, thickness=0.5mm, 350eV (5.9keV), 585eV (59.6keV).S=16mm2, thickness=1.2mm, 310eV (5.9keV), 600eV (59.6keV).Advantages and disadvantages of all types of detectors for X-ray fluorescence analysis are compared. Spectra are presented. Application of different XRF analysers based on developed detectors in medicine, environmental science, industry, cryminalistics and history of art are demonstrated.
We discuss recent results obtained in the development of Si(Li), Si p–i–n, CdTe p–i–n and CdZnTe x-ray detectors with Peltier coolers for fabrication of laboratory and portable XRF analyzers. The characteristics of Si(Li) Peltier-cooled detectors are close to those of detectors cooled with the liquid nitrogen and remain the most preferred type of detectors for the tasks of x-ray fluorescence analysis. Considerable success was obtained in the improvement of the characteristics of CdTe p–i–n detectors and CdZnTe detectors with a metal–semiconductor–metal structure, effective in the energy range up to 100 keV. The spectra of all detectors are presented. Copyright © 2004 John Wiley & Sons, Ltd.
The purpose of this paper is to describe a novel charge transport scheme in semiconductors, in which the field responsible for the charge transport is independent of the depletion field. The application of the novel charge transport scheme leads to the following new semiconductor detectors: 1.1) Semiconductor drift chamber;2.2) Ultralow capacitance - large area semiconductor X-ray spectrometers and photodiodes;3.3) Fully depleted thick CCD.Special attention is paid to the concept of the semiconductor drift chamber as a position sensing detecter for high energy charged particles. Position resolution limiting factors are considered and the values of the resolutions are given.
This paper presents a comparison of HgI2, CdTe and Si (p-i-n) detector technologies for use in X-ray spectroscopy applications in terms of the basic material properties, the detector fabrication techniques and the spectral responses achieved. The requirements imposed on the detector technologies by the design and construction of portable, hand-held instrumentation are discussed. A number of new spectral results are shown. For example, the energy resolution of 596 eV FWHM at 59.5 keV obtained with CdTe (p-i-n) detectors and the energy resolution of 415 eV FWHM at 22 keV measured with HgI2 structures are reported. A discussion of the various practical applications with the above detector technologies is presented.
Thermoelectrically cooled semiconductor detectors, such as Si-PIN, Si-drift, Te and HgI2, coupled to miniaturized low-power X-ray tubes, are well suited in portable systems for energy-dispersive X-ray fluorescence (EDXRF), analysis of archaeological samples. The Si-PIN detector is characterized by a thickness of about 300 μm, an area of about 2×3 mm2, an energy resolution of about 200–250 eV at 5.9 keV and an entrance window of 25–75 μm. The Si-drift detector has approximately the same area and thickness, but an energy resolution of 155 eV at 5.9 keV. The efficiency of these detectors is around 100% from 4 to 10 keV, and then decreases versus energy, reaching ∼9% at 30 keV. Coupled to a miniaturized 10 kV, 0.1 mA, Ca-anode or to a miniaturized 30 kV, 0.1 mA, W-anode X-ray tubes, portable systems can be constructed, which are able to analyse K-lines of elements up to about silver, and L-lines of heavy elements. The Cd1−xZnxTe detector has an area of 4 mm2 and a thickness of 3 mm. It has an energy resolution of about 300 eV at 5.9 keV, and an efficiency of 100% over the whole range of X-rays. Finally the HgI2 detector has an efficiency of about 100% in the whole range of X-rays, and an energy resolution of about 200 eV at 5.9 keV. Coupled to a small 50–60 kV, 1 mA, W-anode X-ray tube, portable systems can be constructed, for the analysis of practically all elements. These systems were applied to analysis in the field of archaeometry and in all applications for which portable systems are needed or at least useful (for example X-ray transmission measurements, X-ray microtomography and so on). Results of in-field use of these detectors and a comparison among these room temperature detectors in relation to concrete applications are presented. More specifically, concerning EDXRF analysis, ancient gold samples were analysed in Rome, in Mexico City and in Milan, ancient bronzes in Sassari, in Bologna, in Chieti and in Naples, and sulfur (due to pollution) in an old roman fresco in the church of S. Stefano Rotondo (Rome).
A compact, inexpensive system for high resolution X-ray and gamma ray detection has been developed. A small, cylindrical hybrid circuit includes detector, FET and feedback components mounted on a small thermoelectric cooler. The hybrid mounts to a small enclosure which provides heat sinking and houses the hybrid preamplifier. A novel feedback technique eliminates feedback resistor noise. Resolution with a 7 mm2 silicon-PIN diode for the 5.9 keV 55Fe peak is 250 eV FWHM. Other solid state detectors may be used with the XR-100T electronics to meet the requirements of a wide range of applications.
An improved compact, high-resolution spectroscopy system has been developed in which Si-PIN or Cd1−xZnxTe radiation detectors and certain preamplifier components are mounted on a thermoelectric cooler. This system combines very high-energy resolution with the convenience of room temperature operation, since the cooling is transparent to the user. Several recent developments have considerably improved performance, resulting in dramatic improvements in both the energy resolution and sensitivity of this commercially available system. In addition, a complete portable spectroscopy system and a very low-noise, general-purpose laboratory preamplifier are now available. These improvements, the measured performance, and field applications of these systems will be discussed.
Detectors with ultrathin entrance windows have been fabricated, which show an overall improvement of the detector performance in the optical and X-ray region as well as for heavy ions. The quantum efficiency was higher than 60% within the entire wavelength range between 200 nm and 800 nm. In the soft X-ray region the spectroscopic resolution could be improved significantly. For the MnKα line a peak to valley ratio of 5700:1 was achieved. Measurements with241Am α-particles revealed an effective “dead” layer width of less than 150Å.The compatibility of the technology to produce thin entrance windows with the planar process allows its application on various pn-junction detector designs. A new silicon drift detector with a total area of 21 mm2 was successfully tested and operated at count rates up to 3 × 107s−1cm−2. At room temperature, the devices have shown an energy resolution for the MnKα line of 227 eV (FWHM) with shaping times of 250–500 ns, decreasing to 152 eV at −20°C. The fast readout in combination with a large detector area, a homogeneous entrance window and an exceptionally low noise without the need of an extensive cooling system makes them especially suited for spectroscopic applications in non-laboratory environments.
By applying the well known techniques of the planar process: oxide passivation, photo engraving and ion implantation, Si pn-junction detectors were fabricated with leakage currents of less than 1 nA cm−2/100 ωm at room temperature. Best values for the energy resolution were 10.0 keV for the 5.486 MeV alphas of 241Am at 22°C using 5 × 5 mm2 detector chips.
To assess the effect of intraparenchymal saline injection on the results of radio-frequency (RF) tissue ablation.
Ex vivo and in vivo animal RF ablation was performed with and without intraparenchymal saline injection. Initially, saline was injected as a bolus (1-20 mL) before RF application. For subsequent in vivo studies, saline was injected as a bolus before RF application or continuously (1 mL/min) during RF application. Finally, 14 patients with liver metastases and one patient with primary cholangiocarcinoma were treated with the continuous infusion technique. A single RF electrode (tip exposure, 1-3 cm) was used with various ablation parameters.
With pretreatment bolus injection of saline, lesions measured 1.4 cm +/- 0.1, 1.6 cm +/- 0.2, and 1.2 cm +/- 0.1 in ex vivo liver, in vivo animal muscle, and in vivo animal liver, respectively. Without saline enhancement, lesion sizes were 1.0 +/- 0.2, 1.2 +/- 0.2, and 0.8 +/- 0.1 cm, respectively. With continuous saline injection in in vivo pig liver, lesion size was 1.8 - 4.1 cm in diameter. In human tumors, necrosis volume was variable, but complete necrosis was seen in 13 of 25 lesions (diameter, 1.2-3.9 cm). Partial necrosis greater than 50% was seen in 12 lesions (diameter, 1.5-4.5 cm).
Saline-enhanced RF ablation might permit percutaneous destruction of large liver lesions.
A CdTe Schottky diode detector of 1 mm thickness was employed in diagnostic x-ray spectroscopy. The detector response to monoenergetic photons was investigated with gamma rays from the calibration sources (241Am and 133Ba). As spectral distortion due to carrier trapping, known as tailing, was small in gamma-ray spectra, the effects of carrier trapping were not taken into account in the calculation of response functions. The distortion due to the transmission of primary x rays and the escape of secondary x rays (K-fluorescent x rays and Compton-scattered x rays) from the crystal was included in the calculated response functions. X-ray spectra corrected using the response functions were in good agreement with the reference spectra obtained with a high-purity germanium detector. The results indicated that correction for the distortion due to carrier trapping is not necessary when using a thin CdTe detector in diagnostic x-ray spectroscopy.
Thermoelectrically cooled X-ray detectors based on Si-PIN and Cd1-xZnxTe (CZT) devices are now widely used in field-portable X-ray fluorescence (XRF) instrumentation. A previous generation of detectors provided high-energy resolution comparable to that of cryogenic detectors, but at much reduced sensitivity. Recent research at Amptek, Inc., Bedford, MA, has explored several approaches to improving the sensitivity of the detectors for higher energy X-rays. First, larger volume Si-PIN detectors have been integrated with two-stage coolers and Amptek's low-noise electronics. Second, CdTe M-π-n detectors have been successfully integrated with the thermoelectric cooler hybrid. These devices have many practical advantages for X-ray spectroscopy. Third, a "dual" detector has been developed, consisting of an Si-PIN for high resolution at the lowest energies stacked on a high-Z semiconductor detector for higher sensitivity at the higher energies. The design and performance of sensors utilizing these three approaches will be presented and the results compared with theoretical expectations. All of these detectors are now commercially available and used in commercial products.
Silicon drift detectors have been tested for X-ray Spectroscopy
applications. By optimizing the detector-FET connection and using a very
low leakage current detector manufacturing process, it has been possible
to achieve a very good energy resolution. The resolution and leakage
current have been studied as a function of temperature, from room
temperature down to -30°C, and as a function of active area. Also
the effects influencing the peak to background ratio have been outlined
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