Search

We investigate the crosstalk between Transition-Edge Sensor (TES) pixels in a 24-pixel hard X-ray spectrometer array fabricated at the Advanced Photon Source, Argonne National Laboratory. Analysis shows thermal cross talk, possibly associated with insufficient thermalization, and rare but larger in magnitude electrical crosstalk between specific perpetrator-victim pixel combinations, potentially due to defects in the bias wiring or microwave multiplexing circuit. We use a method based on group-triggering and averaging to isolate the crosstalk response despite only having access to X-ray photon illumination uniform across the entire array. This allows us to identify thermal and electrical crosstalk between pixel pairs in repeated measurements to the level of 1 part in 1000 or better. In the array under study, the magnitude of observed crosstalk is small but comparable to the resolving power of this pixel design ( E / Δ E ∼ 1000 at 20 keV) and so potentially responsible for a degradation in energy resolution of the array at high incident photon rates. Having proven the methods to identify and quantify crosstalk in our setup, we can now consider mitigations. [ABSTRACT FROM AUTHOR]

X-ray spectrometers based on superconducting transition edge sensors (TESs) are promising in the spectroscopy research. For several X-ray light source facilities in Shanghai, deployment of TES-based spectrometers is proposed. This paper introduces the work on data processing for a TES-based X-ray spectrometer prototype developed at ShanghaiTech University. A data acquisition software is designed and programmed for multi-pixel data recording. The signal analysis method is optimized to best realize the performance of the prototype. We have achieved 12-channel simultaneous data acquisition and better than 9 eV resolution in the range from 2 to 9 keV for 11 TES pixels. [ABSTRACT FROM AUTHOR]

The performance and parameters of the online photon single‐shot spectrometer (PSSS) at the Aramis beamline of the SwissFEL free‐electron laser are presented. The device operates between the photon energies 4 and 13 keV and uses diamond transmission gratings and bent Si crystals for spectral measurements on the first diffraction order of the beam. The device has an energy window of 0.7% of the median photon energy of the free‐electron laser pulses and a spectral resolution (full width at half‐maximum) ΔE/E on the order of 10−5. The device was characterized by comparing its performance with reference data from synchrotron sources, and a parametric study investigated other effects that could affect the reliability of the spectral information. [ABSTRACT FROM AUTHOR]

Four specimens of gametophores and protonemata of Scopelophila cataractae (copper moss) were collected from a stream in Doi Suthep-Pui National Park, Thailand in order to determine heavy metal accumulation and Cu localization. The order of total metal concentrations in the protonemata and leaf cell surfaces of S. cataractae was Fe > Zn > Cu. Significant Cu values (> 400 mg kg−1) were found in both gametophores and protonemata. Growth substrates were considered as a key source of heavy metals in the sampling stream. X-ray spectrometry (EDS micro-analyser) detected the localization of ten elements (C, O, Mg, Al, Si, Ca, S, Cu, Zn and In); substantial atomic percentages of Al, Cu and Zn were noted in leaf surfaces and protonemata. These metallic elements were found in highest proportion. To some extent, cell surfaces at the basal leaf costa showed the highest peak value compared to medial and apical leaf portions (≈ 4.3 at.%). This Cu moss can be used as a bioindicator to reflect anthropogenic activities in stream ecosystems. [ABSTRACT FROM AUTHOR]

X-ray fluorescence computed tomography (XFCT) is a high-sensitivity imaging modality for high-atomic elements such as gadolinium (Gd) or gold (Au). In order to improve the contrast of x-ray fluorescence (XRF) signals in the raw projection data, common XFCT systems use single-pixel x-ray spectrometers to record XRF photons stimulated by the pencil-beam x-ray source and achieve line-by-line scan of the whole object by translating the x-ray source or the object. However, this kind of design results in waiting time of the translation device. One improvement would be to replace the traditional x-ray tube with a spatially distributed multi-beam x-ray source and scan the whole object by switching the exposure of each focus. In this study, we present a design of the XFCT system using a spatially distributed multi-beam source, and a XFCT imaging experiment was performed to investigate its feasibility. Each cold cathode of the x-ray source used in this study was made of carbon nanotubes, and each focus was independently controlled by the electronic control system. The incident beam was collimated by a pinhole array to produce a pencil-beam source. The object scanned by the system was a polymethyl methacrylate (PMMA) cylinder (8 cm in diameter) with Gd (20 mg/ml) and I (100 mg/ml) insertions. Results show that the distribution of iodine (I) and Gd in a PMMA phantom was successfully reconstructed, but the imaging performance was limited by the collimation and exposure mode of the current distributed x-ray source. The practicality of the current distributed x-ray source used for XFCT scan and further optimization of the proposed system are discussed according to the experimental results.

Alpha Particle X-ray Spectrometer (APXS) is one of the two scientific experiments on Chandrayaan-2 rover named as Pragyan. The primary scientific objective of APXS is to determine the elemental composition of the lunar surface in the surrounding regions of the landing site. This will be achieved by employing the technique of X-ray fluorescence (XRF) spectroscopy using in situ excitation source 244Cm emitting both X-rays and alpha particles. These radiations excite characteristic X-rays of the elements by the processes of particle induced X-ray emission and XRF. The characteristic X-rays are detected by the 'state-of-the-art' X-ray detector known as Silicon Drift Detector, which provides high energy resolution, as well as high efficiency in the energy range of 1-25 keV. This enables APXS to detect all major rock forming elements such as, Na, Mg, Al, Si, Ca, Ti and Fe. The flight model of the APXS payload has been completed and tested for various instrument parameters. The APXS provides energy resolution of ~135 eV at 5. 9keV for the detector operating temperature of about -35°C. The design details and the performance measurement of APXS are presented in this paper. [ABSTRACT FROM AUTHOR]

Solar X-ray Monitor (XSM) is one of the scientific instruments onboard Chandrayaan-2 orbiter. The XSM along with instrument CLASS (Chandra's Large Area soft X-ray Spectrometer) comprise the remote X-ray fluorescence spectroscopy experiment of Chandrayaan-2 mission with an objective to determine the elemental composition of the lunar surface on a global scale. XSM instrument will measure the solar X-rays in the energy range of 1-15 keV using state-of-the-art silicon drift detector. The flight model of the XSM payload has been designed, realized and characterized for various operating parameters. XSM provides energy resolution of ~180 eV at 5.9 keV with high time cadence of one second. The X-ray spectra of the Sun observed with XSM will also contribute to the study of solar corona. The detailed description and the performance characteristics of the XSM instrument are presented in this article. [ABSTRACT FROM AUTHOR]

Semiconductor detectors for PIXE applications were fabricated using TlBr crystals. The TlBr detectors had a multiple-electrode detector design to minimize the pulse-height loss due to hole trapping. Electrodes containing thallium metal were employed for the TlBr detectors to suppress the polarization phenomena. Energy resolutions of 2.4, 3.3, and 3.8 keV FWHM for 5.9, 22.1, and 59.5 keV photons, respectively, were obtained for a TlBr detector operating at −50 °C. [ABSTRACT FROM AUTHOR]

We performed small-scale demonstrations at GSFC of high-resolution X-ray TES microcalorimeters read out using a microwave SQUID multiplexer. This work is part of our effort to develop detector and readout technologies for future space-based X-ray instruments such as the microcalorimeter spectrometer envisaged for Lynx, a large mission concept under development for the Astro 2020 Decadal Survey. In this paper we describe our experiment, including details of a recently designed, microwave-optimized low-temperature setup that is thermally anchored to the 55 mK stage of our laboratory ADR. Using a ROACH2 FPGA at room temperature, we read out pixels of a GSFC-built detector array via a NIST-built multiplexer chip with Nb coplanar waveguide resonators coupled to rf-SQUIDs. The resonators are spaced 6 MHz apart (at ∼ 5.9 GHz) and have quality factors of ∼ 15,000. In our initial demonstration, we used flux-ramp modulation frequencies of 125 kHz to read out 5 pixels simultaneously and achieved spectral resolutions of 2.8-3.1 eV FWHM at 5.9 keV. Our subsequent work is ongoing: to-date we have achieved a median spectral resolution of 3.4 eV FWHM at 5.9 keV while reading out 28 pixels simultaneously with flux-ramp frequencies of 160 kHz. We present the measured system-level noise and maximum slew rates and briefly describe our future development work. [ABSTRACT FROM AUTHOR]

A hard X-ray (HXR) spectrometer has been developed to study the runaway electrons during the sawtooth activities and during the runaway current plateau phase on the J-TEXT tokamak. The spectrometer system contains four NaI scintillator detectors and a multi-channel analyzer (MCA) with 0.5 ms time resolution. The dedicated peak detection circuit embedded in the MCA provides a pulse height analysis at count rate up to 1.2 million counts per second (Mcps), which is the key to reach the high time resolution. The accuracy and reliability of the system have been verified by comparing with the hardware integrator of HXR flux. The temporal evolution of HXR flux in different energy ranges can be obtained with high time resolution by this dedicated HXR spectrometer. The response of runaway electron transport with different energy during the sawtooth activities can be studied. The energy evolution of runaway electrons during the plateau phase of runaway current can be obtained. [ABSTRACT FROM AUTHOR]

We have proposed, designed and built a dual-channel x-ray imaging crystal spectrometer (XICS) for spectrally- and spatially-resolved x-ray Thomson scattering (XRTS) measurements in the Matter in Extreme Conditions (MEC) end station at the Linac Coherent Light Source (LCLS). This spectrometer employs two spherically-bent germanium (Ge) 220 crystals, which are combined to form a large aperture dispersive element with a spectral bandwidth of ~300 eV that enables both the elastic and inelastic x-ray scattering peaks to be simultaneously measured. The apparatus and its characterization are described. A resolving power of ~1900 was demonstrated and a spatial resolution of ~12 μm was achieved in calibration tests. For XRTS measurements, a narrow-bandwidth (Δ E / E <0.003) LCLS x-ray free electron laser (XFEL) beam at 5.07 keV was used to probe a dense carbon plasma produced in shock-compressed samples of different forms of carbon. Preliminary results of the scattering experiments from Pyrolytic Graphite samples that illustrate the utility of the instrument are presented. [ABSTRACT FROM AUTHOR]

The improved X-ray optical scheme, the system of registration, and the measurement procedure of the multifunctional synchrotron radiation spectrometer in the dispersive EXAFS mode are described. The results of the spectrometer energy resolution measurements are given. The advantages and disadvantages of traditional and dispersive EXAFS spectrometers are analyzed. Examples of EXAFS spectra measured in the dispersive mode are given. [ABSTRACT FROM AUTHOR]

The goal of this project (BK-284/RT1/2007) is to chose the proper method of car body welding. SMAW could be treated as the main method used in the transport industry. Properties of metal weld deposits depend on many conditions. This paper attempts to study first of all the role of oxide inclusion sites on the transformation austenite->acicular ferrite in steel weld metal deposits and their toughness. Properties of metal weld deposits depend on the amount of acicular ferrite in them. For good toughness over a range of temperatures, metal weld deposits should have a high amount of acicularferrite. Different basic and rutile electrodes were used in order to obtain different asdeposited weld compositions. Impact toughness tests of various deposits were carried out. The microstructure of the welds with different oxygen levels, the inclusion size distribution and approximate chemical composition of inclusions are characterized. Mostobservations and measurements were done with a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The result of the present study implies that it is advantageous to keep oxygen contents in basic and rutile deposits as low as possiblewhen well-developed microstructures of acicular ferrite are desired.

Calorimetric X-ray detectors are very sensitive to their environment. The boundary conditions can have a profound effect on the gain including heat sink temperature, the local radiation temperature, bias, and the temperature of the readout electronics. Any variation in the boundary conditions can cause temporal variations in the gain of the detector and compromise both the energy scale and the resolving power of the spectrometer. Most production X-ray calorimeter spectrometers, both on the ground and in space, have some means of tracking the gain as a function of time, often using a calibration spectral line. For small gain changes, a linear stretch correction is often sufficient. However, the detectors are intrinsically non-linear and often the event analysis, i.e., shaping, optimal filters etc., add additional non-linearity. Thus for large gain variations or when the best possible precision is required, a linear stretch correction is not sufficient. Here, we discuss a new correction technique based on non-linear interpolation of the energy-scale functions. Using Astro-H/SXS calibration data, we demonstrate that the correction can recover the X-ray energy to better than 1 part in 10 $$^{4}$$ over the entire spectral band to above 12 keV even for large-scale gain variations. This method will be used to correct any temporal drift of the on-orbit per-pixel gain using on-board calibration sources for the SXS instrument on the Astro-H observatory. [ABSTRACT FROM AUTHOR]

A 2.2 kJ plasma focus device was analysed as an electron beam and an X-ray source that operates with argon gas refilled at a specific pressure. Time-resolved X-ray signals were observed using an array of PIN diode detectors, and the electron beam energy was detected using a scintillator-assisted photomultiplier tube. The resultant X-rays were investigated by plasma focus discharge for pressures ranging from 1.5 mbar to 2.0 mbar. This range corresponded to the significant values of X-ray yields and electron beam energies from the argon plasma. The electron temperature of argon plasma at an optimum pressure range was achieved by an indirect method using five-channel BPX65 PIN diodes of aluminum foils with different thicknesses. X-ray yield, electron beam energy, and electron temperature of argon plasma were achieved at 1.5-2.0 mbar because of the strong bombardment of the energetic electron beam. [ABSTRACT FROM AUTHOR]

Pion-nucleon scattering lengths are directly related to the ground-state level shift and broadening in pionic hydrogen as well as to the pionic deuterium level shift. The level broadening in deuterium measures the strength of pion threshold-production in proton-proton reactions. However, collisional processes during the atomic de-excitation cascade considerably complicate the analysis of X-ray line shapes in order to extract the hadronic broadening. Therefore, additionally the purely electromagnetic twin system muonic hydrogen was studied. Results of these experiments performed at PSI by using a high-resolution crystal spectrometer are discussed in the context with a new analysis approach for the hadronic broadening. [ABSTRACT FROM AUTHOR]

Alpha Particle X-ray Spectrometer (APXS) payload configuration for Chandrayaan-2 rover has been completed recently and fabrication of mechanical assembly, PCB layout design and fabrication are in progress. Here we present the design and performance evaluation of various subsystems developed for APXS payload. The low energy threshold of <1 keV and the energy resolution of ∼150 eV at 5.9 keV, for the Silicon Drift Detector (SDD), as measured from the developed APXS electronics is comparable to the standard spectrometers available off-the-shelf. We have also carried out experiments for measuring fluorescent X-ray spectrum from various standard samples from the USGS catalog irradiated by the laboratory X-ray source 241 Am with 1 mCi activity. It is shown that intensities of various characteristic X-ray lines are well correlated with the respective elemental concentrations. [ABSTRACT FROM AUTHOR]

The remote X-ray fluorescence spectroscopy is a powerful technique to investigate the elemental abundances in the atmosphere-less planetary bodies. The experiment involves measuring spectra of fluorescent X-rays from lunar surface using a low energy X-ray detector onboard an orbiting satellite. Since the flux of fluorescent X-ray lines critically depend on the flux and spectrum of the incident solar X-rays, it is essential to have simultaneous and accurate measurement of X-ray from both Moon and Sun. In the context of Moon, this technique has been employed since early days of space exploration to determine elemental composition of lunar surface. However, so far it has not been possible to exploit it to its full potential due to various reasons. Therefore it is planned to continue the remote X-ray fluorescence spectroscopy experiment on-board Chandrayaan-2 which includes both lunar X-ray observations and solar X-ray observations as two separate payloads. The lunar X-ray observations will be carried out by Chandra Large Area Soft x-ray Spectrometer (CLASS) experiment; whereas the solar X-ray observations will be carried out by a separate payload, Solar X-ray Monitor (XSM). Here we present the overall design of the XSM instrument, the present development status as well as preliminary results of the laboratory model testing. XSM instrument will have two packages namely – XSM sensor package and XSM electronics package. XSM will accurately measure spectrum of Solar X-rays in the energy range of 1–15 keV with energy resolution ∼200 eV @ 5.9 keV. This will be achieved by using state-of-the-art Silicon Drift Detector (SDD), which has a unique capability of maintaining high energy resolution at very high incident count rate expected from Solar X-rays. XSM onboard Chandrayaan-2 will be the first experiment to use such detector for Solar X-ray monitoring. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the mechanism of action at the interface between a commercially available Y-TZP and its veneering ceramic after final firing. Particular attention was paid, from a microstructural point of view, to evaluating the effects of different surface treatments carried out on the zirconia. Methods: In total, 32 specimens of presintered zirconia Y-TZP (LavaFrame, 3M ESPE, Germany) were cut with a low-speed diamond blade. The specimens were divided in two major groups, for testing after fracture or after mirror finishing, and were sintered following the manufacturer's instructions. Each major group was then randomly divided into four subgroups, according to using or not using the dedicated framework modifier, with or without a preliminary silica coating (CoJet, 3 M ESPE). A suitable veneering ceramic was used for each group (Lava Ceram Overlay Porcelain, 3 M ESPE). A detailed microstructural study of the interfaces of the zirconia-veneering ceramic was performed using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer to evaluate chemical variation at the interfaces. Results: When the framework modifier was not applied on the Y-TZP surface, microdetachments, porosities, and openings in the ceramic layer were observed at the interlayers. A degree of diffusion of different elements through the interfaces from both the zirconia and veneering layers was detected. Conclusions: Application of the framework modifier can increase the wettability of the zirconia surfaces, allowing a continuous contact with the veneering layer. The microanalysis performed showed the presence of a reaction area at the interface between the different materials. Clinical significance: the increase of the wettability of the zirconia surface could improve the adhesion at interface with the veneering ceramic and reduce the clinical failure as chipping or delamination. [ABSTRACT FROM AUTHOR]

The elemental abundances of lunar surface are the important clues to study the formation and evolution history of the Moon. In 2010, China's Chang'E-2 (CE-2) lunar orbiter carried a set of X-ray spectrometer (XRS) to investigate the elemental abundances of the lunar surface. During CE-2's life span around the Moon, the XRS experienced several events of solar flare. The X-ray solar monitor onboard recorded the spectra of solar X-rays at the same time. In this paper, we introduced the XRS instrument and data product. We analyzed the characteristics of the XRS data. Using the data obtained during an M solar flare event which had occurred on Feb. 16, 2011, we derived the elemental abundances of Mg, Al, Si, Ca and Fe of the lunar surface in the Oceanus Procellarum. Finally, we discussed the factors that influence the accuracy of the inversion. [ABSTRACT FROM AUTHOR]

The Super Advanced X-ray Emission Spectrometer (SAXES) at the Swiss Light Source contains a high resolution Charge-Coupled Device (CCD) camera used for Resonant Inelastic X-ray Scattering (RIXS). Using the current CCD-based camera system, the energy-dispersive spectrometer has an energy resolution (E/ΔE) of approximately 12,000 at 930eV. A recent study predicted that through an upgrade to the grating and camera system, the energy resolution could be improved by a factor of 2. In order to achieve this goal in the spectral domain, the spatial resolution of the CCD must be improved to better than 5µm from the current 24µm spatial resolution (FWHM). The 400eV–1600eV energy X-rays detected by this spectrometer primarily interact within the field free region of the CCD, producing electron clouds which will diffuse isotropically until they reach the depleted region and buried channel. This diffusion of the charge leads to events which are split across several pixels. Through the analysis of the charge distribution across the pixels, various centroiding techniques can be used to pinpoint the spatial location of the X-ray interaction to the sub-pixel level, greatly improving the spatial resolution achieved. Using the PolLux soft X-ray microspectroscopy endstation at the Swiss Light Source, a beam of X-rays of energies from 200eV to 1400eV can be focused down to a spot size of approximately 20nm. Scanning this spot across the 16µm square pixels allows the sub-pixel response to be investigated. Previous work has demonstrated the potential improvement in spatial resolution achievable by centroiding events in a standard CCD. An Electron-Multiplying CCD (EM-CCD) has been used to improve the signal to effective readout noise ratio achieved resulting in a worst-case spatial resolution measurement of 4.5±0.2μm and 3.9±0.1μm at 530eV and 680eV respectively. A method is described that allows the contribution of the X-ray spot size to be deconvolved from these worst-case resolution measurements, estimating the spatial resolution to be approximately 3.5µm and 3.0µm at 530eV and 680eV, well below the resolution limit of 5µm required to improve the spectral resolution by a factor of 2. [ABSTRACT FROM AUTHOR]

The Northland Allochthon is a displaced rock unit in New Zealand. It overlies the autochthonous sediments of non-marine to marine transgressive sediments and unconformably overlain by the Waitemata and correlative groups of Upper Oligocene-Lower Miocene age. Lithologically, the allochthonous unit is mostly composed of sandstone, siltstone, greensand, siliceous mudstone, argillaceous micritic limestone, and rare coal measures, along with dispersed organic matter. In this paper, the provenance & tectonic setting of different lithofacies of Northland Allochthon rocks is inferred using geochemical analysis. Major and trace element composition of these lithofacies are analyzed by X-ray spectrometer using standard analytical techniques. The results indicate that SiO2 and Al2O3 are most abundant with dominance of quartz, feldspar and clay. The SiO2 correlate negatively with all other oxides, however, Al2O3 correlate positively. Variation of CaO, K2O and Na2O content appears to be independent of Al2O3 content. This indicates that major element variation could result from processes other than simple dilution by Si2O2 and Al2O3. Trace elements exhibit a systematic relationship with Al2O3 and its concentration increase as grain size and SiO2 content decreases. K2O/Na2O vs SiO2 discriminant plot indicates the tectonic setting of Northland Allochthon rocks, New Zealand belong to active continental margin. Immobility of elements is indicated by Zr and Yttrium concentration. Depletion of Al is indicated by the replacement of plagioclase and matrix by calcite tends to behave like Ti as suggested by a positive correlation between these elements [ABSTRACT FROM AUTHOR]

We present an Application Specific Integrated Circuit (ASIC) for high resolution X-ray spectrometers (XRS) in radiation harsh environment (such as Jovian system). The ASIC was designed to read out signals from low resistivity pixelated Silicon-Drift-Detectors (SDD) to ensure radiation hardness. The readout is done by wire-bonding the anodes to the inputs of the ASIC. The ASIC dissipates 32 mW and provides 16 channels of low-noise charge amplification, high-order shaping with baseline stabilization, discrimination, pile-up rejection, and peak detection with analog memory. The readout is sparse and based on a custom low-power tri-stable low-voltage differential signaling digital interface. A unit of 64 SDD pixels, read out by four ASICs, covers an area of 12.8 cm^2, and dissipates less than 20 mW/cm^2. The ASICs were powered on and irradiated using a beam line with 203 MeV protons, to total doses ranging from 0.25 Mrad to 12 Mrad. Performance degradation due to radiation-induced leakage current was observed to peak around 2 Mrad dose. Critical contributors to the degradation were identified through simulation and measurements, and corresponding circuitry was thus modified to address the issues. Measurements on the radiation-resistant design have shown excellent radiation resistance at total doses ranging from 1 to 8 Mrad. [ABSTRACT FROM PUBLISHER]

The overall performance of a 100-pixel superconducting tunnel junction (STJ) array detector in the soft X-ray region was determined by measuring fluorescent X-rays from light elements. The yield of working STJs in the fabricated detector was 90%, and the leakage current for these 90 STJs was 11.6±2.5 nA. The STJs had an intrinsic energy resolution for O-K α X-rays (524.9 eV) of 10.2±1.7 eV (FWHM). The deviation from energy linearity was −0.042±0.45%, 0.793±0.91%, and 0.135±1.31% for O-K α (524.9 eV), N-K α (392.4 eV) and B-K α (183.3 eV) X-rays, respectively. Most of the STJs exhibited uniform X-ray detection characteristics. In addition, the detector could discriminate the N-K α peak in the fluorescent X-ray spectrum from n-type SiC doped with 300 ppm nitrogen. [ABSTRACT FROM AUTHOR]

Abstract: Silicon Drift Detector (SDD) based X-ray spectrometer has been developed for obtaining the elemental composition of unknown samples by detecting fluorescent X-rays in the energy region 1–25 keV by a non-destructive process. The use of new technology X-ray detector provides good energy resolution for detecting the elements separated with ∼150 eV apart. Here we present the design of a complete X-ray spectrometer intended for use in the future space-born experiment. The low energy threshold of <1 keV and the energy resolution of ∼150 eV at 5.9 keV, as measured from the system is comparable to the standard spectrometers available off-the-shelf. We evaluated the system performance for different signal peaking time, as well as for different input count rates and show that the performance remains stable for incident count rate up to 20,000 counts per second. We have also carried out a ‘proof of concept’ experiment of measuring fluorescent X-ray spectrum from various standard XRF samples from the USGS catalog irradiated by the laboratory X-ray source 241Am with 1 mCi activity. It is shown that intensities of various characteristic X-ray lines are well correlated with the respective elemental concentrations. A specific effort has been made while designing the developed X-ray spectrometer to use electronic components which are available in space grade so that the same electronic design can be used in the upcoming planetary missions with appropriate mechanical packaging. [Copyright &y& Elsevier]

Abstract: We present a forward modelling technique for calculating the surface X-ray spectra for a variety of lunar terrains. Our calculations considered variations in solar fluxes from solar quiescent condition to large flare activity (M1 flare), and expected elemental concentrations in the target, as well as yield, instrumental, and viewing geometry parameters for X-ray induced fluorescence from the lunar surface. Additionally, we present estimates of anticipated XRF signals from prominent Kα lines observable by a collimated 14cm2 X-ray detector from a 100km lunar orbit with ∼20km spatial resolution. Our results show that Mg, Al and Si characteristic Kα lines can be observed for all solar conditions. The Ca Kα lines line can be differentiated from a fixed background during more energetic solar conditions such as C1 and M1 flares, whereas Ti and Fe lines are identifiable only during C1 and M1 solar flare conditions for Apollo 12 site composition. Both the Kα X-ray intensity ratios of Mg/Si and Al/Si correlate well with concentration ratios of Mg/Si and Al/Si, respectively, for B1 and M1 solar conditions. The Kα X-ray intensity ratios of Fe/Si and Ca/Si correlates with concentration ratios of Fe/Si and Ca/Si, respectively, for M1 solar condition. In principle, the modelling technique outlined here can be used to determine absolute elemental abundances (Mg, Al, Si, Ca, Ti and Fe) from X-ray spectra measured during recent and future lunar missions. [ABSTRACT FROM AUTHOR]

Abstract: A study of the single-photon events generated by the interaction of X-rays up to 60keV with a true two-phase charge coupled device (CCD) is reported. In particular, a relevant classification of the events is carried out according to their size and collected charge. This classification shows the occurrence of two main groups, characterized by a quite large difference in the ADU values that has been observed between events having different sizes but coming from photons with the same energy. Based upon 2D numerical calculations accounting for the charge cloud dynamics, diffusion and recombination, an explanation is suggested for this difference, arising from the difference in the electric field strength in the point of initial interaction. Moreover, the relative abundance of these two groups was found to be energy dependent. A model accounting for the true two-phase pixel structure was found to be a valid tool for a correct prediction of this abundance and an enhanced reconstruction of the spectra of the impinging photons. [Copyright &y& Elsevier]

We present an application specific integrated circuit (ASIC) for high-resolution X-ray spectrometers. The ASIC is designed to read out signals from a pixelated silicon drift detector (SDD). Each hexagonal pixel has an area of 15 mm2 and an anode capacitance of less than 100 fF. There is no integrated Field Effect transistor (FET) in the pixel, rather, the readout is done by wire-bonding the anodes to the inputs of the ASIC. The ASIC provides 14 channels of low-noise charge amplification, high-order shaping with baseline stabilization, and peak detection with analog memory. The readout is sparse and based on low voltage differential signaling. An interposer provides all the interconnections required to bias and operate the system. The channel dissipates 1.6 mW. The complete 14-pixel unit covers an area of 210 mm2, dissipates 12 mW cm-2, and can be tiled to cover an arbitrarily large detection area. We measured a preliminary resolution of 172 eV at -35 degC on the 6 keV peak of a 55Fe source. [ABSTRACT FROM PUBLISHER]

Abstract: The back-illuminated charge coupled devices (CCD) are suitable for soft X-ray photon detection. Their nominal performances suggest that they can boost both efficiency and resolving power of X-ray spectrometers based on diffraction gratings and two-dimensional position sensitive detectors. We tested the performances of two commercially available CCDs, intended to replace a more traditional microchannel plate (MCP) detector. Our tests show that the devices have excellent performances in terms of dark current, response linearity, detection efficiency and spatial resolution. We observed that the CCDs have better efficiency (more than 10 times) and better resolution (∼3 times) than the MCP. Moreover we found an intrinsic limit for the spatial resolution, which is almost independent of the detector pixel size and is estimated around 25μm. [Copyright &y& Elsevier]

A new X-ray spectrometer has been constructed for Compton profile measurements at beamline ID15B of the ESRF. The spectrometer is based on a novel idea, dispersion compensation, which was proposed earlier. A cylindrically bent Laue monochromator focuses ∼90 keV synchrotron radiation at about 0.7 m before the sample, and produces a well defined energy or wavelength gradient on the sample. A cylindrically bent Laue analyser almost perfectly compensates this wavelength gradient. Using an Al sample, it has been confirmed that the new spectrometer improves the counting rate by a factor of two compared with the previously constructed 30 keV and 60 keV spectrometers, with a comparable momentum resolution. Because of reduced absorption owing to use of high-energy X-rays, the enhancement of the counting rate is spectacular for heavy-element materials. [ABSTRACT FROM AUTHOR]

A new focusing spectrometer employing Johann geometry has been built and permanently installed at the wiggler beamline W1 at the Hamburger Synchrotron Strahlungslabor (HASYLAB) am Deutschen Elektronen Synchrotron (DESY). It is now available for user operation. The design of the spectrometer is optimized for the use of a large source spot size at the DORIS storage ring as well as for simple operation and robustness under user-mode conditions. Nevertheless, the ideal source for enlarging the number of possible applications in the future would be an undulator at one of the PETRA III beamlines. In the following the spectrometer design is described and boundary conditions such as the available energy range for future experiments are discussed. Two benchmark experiments, resonant inelastic X-ray scattering (RIXS) and X-ray absorption fluorescence spectroscopy (XAFS), on samples with complicated matrices demonstrate the performance of the new instrument. [ABSTRACT FROM AUTHOR]

A high-resolution spectrometer aimed at performing experiments of inelastic X-ray scattering by electronic excitations is described. The spectrometer has been installed at the D12A-XRD1 beamline of the National Synchrotron Light Laboratory (LNLS), in Campinas, Brazil. Synchrotron radiation is monochromated to about 6 kev and focused horizontally onto the sample by a sagittally focusing Si(lll) double-crystal monochromator in non-dispersive setting. The spectrometer operates in Rowland circle geometry and is based on a focusing Si(333) analyses in near-backdiffraction geometry for energy analysis of inelastically scattered photons. The analyses works at a fixed Bragg angle, so energy transfers are obtained by varying the incident photon energy. A relative energy resolution of the whole spectrometer of ∼1.5 x 10-4 at 5.93 kev has been achieved. As an example of application, inelastic X-ray scattering by plasmon excitation in polycrystalline Be was measured. Test results demonstrate that inelastic X-ray scattering experiments with eV energy resolution and an acceptable counting rate are feasible at the LNLS when focused on plasmon and particle-hole excitations. [ABSTRACT FROM AUTHOR]

The swept charge device has been developed using CCD technology to perform photon counting X-ray spectroscopy in the 0.5–10 keV band as an alternative to silicon PIN and drift diode detectors. The key benefits of the detector are large area, combined with reduced electrical interconnects, with X-ray performance obtained using modest cooling to around −20°C. Here we test the technology for its suitability for space use where solar protons degrade the CTI of the detector leading to a degradation in its resolution as a spectrometer. We report on the irradiation experiments conducted and discuss changes in leakage current and energy resolution in the detector. [Copyright &y& Elsevier]

The PN-CCD camera on the XMM-Newton X-ray astronomy satellite is the most advanced X-ray spectrometer combining high quantum efficiency, high-speed readout and excellent energy resolution. According to the fullframe concept, the whole 6×6 cm2 large CCD-chip area is used as image area, i.e. is sensitive and exposed to X-rays. The camera operates since January 2000 successfully in space without performance degradation. Based on the concept and technology development of the XMM-Newton PN-CCD, the ‘frame store PN-CCD’, a further development of the detector has been proposed. For the new detector a frame store area is added, adjacent to the image area, to allow in parallel photon exposure in the image area and signal readout of the previous image in the frame store area. The concept and the new features of the device will be described here. This comprises in particular a reduced probability of out-of-time event occurrence, the optimization of electronic noise and charge transfer losses as well as a method to obtain a cleaner low-energy response. The first measurements with the new frame store PN-CCD are presented with focus on the above addressed detector parameters. It is planned to apply the device as focal plane instrument for the ROSITA mission that has the aim to extend the ROSAT all-sky survey towards higher energies. [Copyright &y& Elsevier]

A portable (200×100×100 mm3), high-luminosity, spherically bent crystal spectrometer was designed to measure very low emissivity X-ray spectra of different elements with spatial resolution in a wide spectral range (1.2−19.6 A˚). A large (50×15 mm2) open aperture mica spherically bent crystal with R=150 mm was used as dispersive and focusing element. This spectrometer was associated with a large sensitive area (φ=40 mm) micro-channel plates assembly. This apparatus provides simultaneously high spectral (λ/δλ∼1800) and spatial (100–200 μm) resolutions. Its large tunability allowed, without any adjustment of the spectrometer set-up, to record spectra in the 1.38–17.5 A˚ wavelength range. We used the X-ray emission of femtosecond laser-produced plasmas from different materials ((CF2)n, CaF2, Cu, Al) to test the spectrometer. Thanks to the high sensitivity (high collection efficiency) of the system, high quality space-resolved X-ray spectra of Fluorine and Aluminum plasmas were obtained on a single laser shot. [Copyright &y& Elsevier]