The correct identification of rock types is critical for understanding the origins and history of any particular rock body. Laser-induced breakdown spectroscopy (LIBS) has developed into an excellent ...analytical tool for geological materials research because of its numerous technical advantages compared with traditional methods. The coupling of LIBS with advanced multivariate analysis has received increasing attention because it facilitates the rapid processing of spectral information to differentiate and classify samples. In this study, we collected LIBS datasets for 16 sedimentary rocks from Triassic strata in Sichuan Basin. We compared the performance of two types of spectrometers (Czerny–Turner and Echelle) for classification of rocks using two advanced multivariate statistical techniques, i.e., partial least squares discriminant analysis (PLS-DA) and support vector machines (SVMs). Comparable levels of performance were achievable when using the two systems in the best signal reception conditions. Our results also suggest that SVM outperformed PLS-DA in classification performance. Then, we compared the results obtained when using pre-selected wavelength variables and broadband LIBS spectra as variable inputs. They provided approximately equivalent levels of performance. In addition, the rock slab samples were also analyzed directly after being polished. This minimized the analysis time greatly and showed improvement of classification performance compared with the pressed pellets.
•SVM and PLS-DA were compared using two spectrometers to classify sedimentary rocks.•SVM combined with LIBS improved the classification accuracy compared with PLS-DA.•Minimal difference using pre-selected and broadband spectra as variable inputs•Improved classification performance achievable using polished rock slab samples
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBJE, UL, UM, UPCLJ, UPUK
Measuring the neutron spectrum on the Linac head using a passive type neutron detector is relatively easier than an active type detector because it does not require the involvement of operators who ...work in a high radiation area. Neutron spectrum measurements with passive foil activation neutron detectors in a single-moderator are more practical and easier than multi-foil techniques. This technique is quite simple, easy to make, low cost, and the measurement time is relatively short. This spectrometer is designed by placing seven passive Au detectors at varying depths in a single-cylindrical moderator. The response function for each detector is calculated by MCNPX 2.7 program and used ENDF7 as a nuclear data library. Detector foil activity was measured using a gamma spectrometer, and the neutron spectrum was obtained using the unfolding technique using the UMG 3.3 program. The results of measuring the neutron spectrum measurements have been carried out at a position 10 cm below the head of the Elekta Precise 10 MV Linac was 2.73 × 105 n/cm2·s, where the fast neutron from these results are 4% higher when compared to the simulation results using PHITS.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Our group is currently developing a multilayer neutron spectrometer based on moderator combination selection to evaluate neutron energy spectra in irradiation fields for boron neutron capture therapy ...(BNCT). In a previous study, we optimally selected (based on simulations) liquid moderator combinations of the spectrometer to achieve high accuracy in the evaluated neutron energy spectra. According to the optimization result, we conducted a spectrometer verification test in the BNCT irradiation field at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor (KUR-HWNIF). The neutron energy spectrum result was evaluated, and the uncertainty was found to be less than 15%. The experimental results prove that the multilayer neutron spectrometer based on moderator combination selection effectively evaluates the neutron energy spectrum in a BNCT irradiation field.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A set of electron time‐of‐flight spectrometers for high‐resolution angle‐resolved spectroscopy was developed for the Small Quantum Systems (SQS) instrument at the SASE3 soft X‐ray branch of the ...European XFEL. The resolving power of this spectrometer design is demonstrated to exceed 10 000 (E/ΔE), using the well known Ne 1s−13p resonant Auger spectrum measured at a photon energy of 867.11 eV at a third‐generation synchrotron radiation source. At the European XFEL, a width of ∼0.5 eV full width at half‐maximum for a kinetic energy of 800 eV was demonstrated. It is expected that this linewidth can be reached over a broad range of kinetic energies. An array of these spectrometers, with different angular orientations, is tailored for the Atomic‐like Quantum Systems endstation for high‐resolution angle‐resolved spectroscopy of gaseous samples.
A set of electron time‐of‐flight spectrometers for high‐resolution angle‐resolved spectroscopy has been developed for the Small Quantum Systems (SQS) instrument at the SASE3 soft X‐ray branch of the European XFEL.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
•Smartphone-controlled NIR spectrometer was successfully used to detect FBs contamination in corn.•The spectral absorbance intensity of corn samples varied with the different levels of FBs ...contamination.•LPLS-S showed higher prediction accuracy of FBs content in corn than PLS and SVM models.•PLS-DA and SVM-DA showed similar results for classifying corn samples according to the MRL of FBs.
A portable near-infrared (NIR) spectrometer coupled with chemometrics for the detection of fumonisin B1 and B2 (FBs) in ground corn samples was proposed in the present work. A total of 173 corn samples were collected, and their FB contents were determined by HPLC–MS/MS. Partial least squares (PLS), support vector machine (SVM) and local PLS based on global PLS score (LPLS-S) algorithms were employed to construct quantitative models. The performance of the SVM and LPLS-S was better than that of PLS, and the LPLS-S presented the lowest RMSEP (12.08 mg/kg) and the highest RPD (3.44). Partial least squares-discriminant analysis (PLS-DA) and support vector machine-discriminant analysis (SVM-DA) were used to classify corn samples according to the maximum residue limit (MRL) of FBs, and the discriminant accuracy of both the PLS-DA and SVM-DA algorithms was above 86.0%. Thus, the present study provided a rapid method for monitoring FB contamination in corn samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
SANS‐J (a pinhole small‐angle neutron scattering spectrometer at research reactor JRR3, Tokai, Japan) was reconstructed as a focusing and polarized neutron small‐angle scattering spectrometer ...(SANS‐J‐II). By employing focusing lenses of a biconcave MgF2 crystal or of a sextupole permanent magnet and a high‐resolution photomultiplier, the minimum accessible magnitude of the scattering vector qmin was improved from 3 × 10−3Å−1 to an ultra‐small‐angle scattering (USAS) of 3 × 10−4 Å−1. Compared with a Bonse–Hart double‐crystal method, the advantages of focusing USAS are the efficient detection of anisotropic USAS with an area detector, an improvement in q resolution Δq/q at conventional magnitudes of the scattering vector q ~ 10−3 Å−1 and a gain in neutron flux in the conventional q region of q ~ 10−3 Å−1.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Characterization and performance of the DTAS detector Guadilla, V.; Tain, J.L.; Algora, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2018, Volume:
910, Issue:
C
Journal Article
Peer reviewed
Open access
DTAS is a segmented total absorption γ-ray spectrometer developed for the DESPEC experiment at FAIR. It is composed of up to eighteen NaI(Tl) crystals. In this work we study the performance of this ...detector with laboratory sources and also under real experimental conditions. We present a procedure to reconstruct offline the sum of the energy deposited in all the crystals of the spectrometer, which is complicated by the effect of NaI(Tl) light-yield non-proportionality. The use of a system to correct for time variations of the gain in individual detector modules, based on a light pulse generator, is demonstrated. We describe also an event-based method to evaluate the summing-pileup electronic distortion in segmented spectrometers. All of this allows a careful characterization of the detector with Monte Carlo simulations that is needed to calculate the response function for the analysis of total absorption γ-ray spectroscopy data. Special attention was paid to the interaction of neutrons with the spectrometer, since they are a source of contamination in studies of β-delayed neutron emitting nuclei.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Due to advantages such as the high efficiency of light utilization, small volume, and vibration resistance, digital micro-mirror device (DMD)-based spectrometers are widely used in ocean ...investigations, mountain surveys, and other field science research. In order to eliminate the stray light caused by DMDs, the stray light in DMD-based spectrometers was first measured and analyzed. Then, the stray light was classified into wavelength-related components and wavelength-unrelated components. Moreover, the noise caused by the stray light was analyzed from the perspective of encoding equation, and the de-noising decoding equation was deduced. The results showed that the accuracy range of absorbance was enhanced from 0, 1.9 to 0, 3.1 in single-stripe mode and the accuracy range of absorbance was enhanced from 0, 3.8 to 0, 6.3 in Hadamard transform (HT) multiple-stripe mode. A conclusion can be drawn that the de-noising strategy is feasible and effective for enhancing the SNR in DMD-based spectrometers.
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Online quantitative analysis of the reaction gas or tail gas of industrial production process can help to adjust the production process and improve product quality in time, which is of great ...significance to the transformation and upgrading of the relevant industries. However, due to the influence of industrial production cost, the application of expensive high-resolution mass spectrometer in industrial online quantitative analysis is relatively limited, while low-resolution mass spectrometer may detect the mass spectra with overlapping peaks, causing difficulties in the accurate quantification of reaction or tail gases. Although the current online quantitative analysis methods are relatively mature, there are still some spaces for optimization in terms of quantitative accuracy, method applicability and equipment complexity. For more accurate and more efficient online quantitative analysis, an online process mass spectrometer was proposed to detect the reaction gas or tail gas and separate the overlapping spectral peaks. At first, the component gases and their corresponding contents of the reaction gas or tail gas under measurement were accurately predicted according to industrial production scenarios, obtaining a prediction matrix and formulating a calibration standard gas. Secondly, all the overlapping spectral peaks of the calibration standard gas were obtained through finding the standard mass spectra of each component gas, and the simplest ratio matrix was constructed according to its relationship with the main peaks of each component gas, which was corrected by formulating the ratio standard gases with the same content as the relevant component gases. Then, the calibration matrix was obtained through detecting and calculating the calibration standard gas with the mass spectrometer, together with the prediction matrix and the ratio matrix, the calibration mathematical model was constructed to obtain the relative sensitivity matrix. Finally, a quantitative mathematical model was constructed with the calculated relative sensitivity matrix, the corrected ratio matrix and the detection matrix obtained after detecting and calculating the reaction gas or tail gas under measurement, and the content matrix of each component gas was obtained to monitor and control the industrial production process in real time. The online quantitative analysis of representative yeast fermenter tail gas showed that the method has high accuracy and strong applicability. After several rounds of online quantitative analysis experiments, the maximum quantitative error could be controlled within 0.4%, and the maximum quantitative relative standard deviation could be limited within 2%.
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