• Design and analysis of a hybrid X-ray transmission and diffraction system

      Greenberg, J.A.; Carpenter, J.; Coccarelli, D.; Ding, Y.; Yang, S.; Fang, E.; Brumbaugh, K.; Gregory, C.; Ashok, A.; Kapadia, A.J.; et al. (SPIE, 2021)
      Aviation security, mail inspection, medical diagnostics and many other industries all face the same challenge: to accurately identify the presence of a target material concealed within a cluttered surrounding environment. X-ray systems that combine transmission and diffraction measurements promise excellent detection performance with low false alarm rates; however, conventional approaches to combining these measurements typically under-utilize the available information and result in higher overall system resource costs. Here, we consider a fully integrated approach to hybrid X-ray transmission and diffraction systems and discuss simulation- and experimental-based investigations of the design and performance (both imaging and detection) of such systems. Based on this analysis, we describe a hybrid system capable of scanning boxes and/or luggage and report its ability to distinguish materials of interest to aviation security and pharmaceutical inspection. © 2021 SPIE.
    • Fluorlamprophyllite, Na-3(SrNa)Ti-3(Si2O7)(2)O2F2, a new mineral from Pocos de Caldas alkaline massif, Morro do Serrote, Minas Gerais, Brazil

      Andrade, Marcelo B.; Yang, Hexiong; Downs, Robert T.; Färber, Gunnar; Contreira Filho, Reynaldo R.; Evans, Stanley H.; Loehn, Clayton W.; Schumer, Benjamin N.; Univ Arizona, Dept Geosci (MINERALOGICAL SOC, 2018-02)
      A new mineral species, fluorlamprophyllite (IMA2013-102), ideally Na3(SrNa)Ti-3(Si2O7)(2)O2F2, has been found in the Pocos de Caldas alkaline massif, Morro do Serrote, Minas Gerais, Brazil. Alternatively, the idealized chemical formula could be written as (SrNa)[(Na3Ti)F-2][Ti-2(Si2O7)(2)O-2], setting the large interlayer cations before the cations of the layer. Fluorlamprophyllite is the F-analogue of lamprophyllite. It is associated with aegirine, analcime, natrolite, nepheline and microcline. Fluorlamprophyllite crystals are brownish-orange and bladed. The mineral is transparent with a pale yellow streak and an adamantine lustre. It is brittle and has a Mohs hardness of similar to 3; cleavage is perfect on {100} and no parting was observed. The calculated density is 3.484 g/cm(3). Optically, fluorlamprophyllite is biaxial (+), with alpha= 1.735(7), beta = 1.749(7) and gamma = 1.775(9) and 2V(meas) = 72(3)degrees. An electron microprobe analysis produced an average composition (wt.%) (9 points) of Na2O 10.63(30), K2O 0.47(3), SiO2 30.51(13), SrO 18.30(24), MgO 0.81(17), Al2O3 0.23(2), CaO 1.11(7), MnO 5.03(38), TiO2 27.41(87), Fe2O3 2.45(37), F 2.86(23), plus H2O 1.00 (added to bring the total close to 100%), O = F 1.20, with the total = 98.61%. The elements Nb and Ba were sought, but contents were below microprobe detection limits. The resultant chemical formula was calculated on the basis of 18 (O + F) atoms per formula unit. The addition of 1.00 wt.% H2O brought [F+(OH)] = 2 pfu, yielding (Na2.63Sr1.35Mn0.54Ca0.15Mg0.15K0.08)(Sigma 4.90)(Ti2.63Fe0.24Al0.04)(Sigma 2.91)Si3.89O16[F-1.15(OH)(0.85)](Sigma 2.00). The mineral is monoclinic, with space group C2/m and unit-cell parameters a - 19.255(2), b - 7.0715(7), c - 5.3807(6) A, beta = 96.794(2)degrees and V = 727.5(1) A(3). The structure is a layered silicate inasmuch as the O atoms are arranged in well-defined, though not necessarily close-packed layers.
    • Mineralogy of Vera Rubin Ridge From the Mars Science Laboratory CheMin Instrument

      Rampe, E. B.; Bristow, T. F.; Morris, R. V.; Morrison, S. M.; Achilles, C. N.; Ming, D. W.; Vaniman, D. T.; Blake, D. F.; Tu, V. M.; Chipera, S. J.; et al. (AMER GEOPHYSICAL UNION, 2020-09-24)
      Vera Rubin ridge (VRR) is an erosion-resistant feature on the northwestern slope of Mount Sharp in Gale crater, Mars, and orbital visible/shortwave infrared measurements indicate it contains red hematite. The Mars Science LaboratoryCuriosityrover performed an extensive campaign on VRR to study its mineralogy, geochemistry, and sedimentology to determine the depositional and diagenetic history of the ridge and constrain the processes by which the hematite could have formed. X-ray diffraction (XRD) data from the CheMin instrument of four samples drilled on and below VRR demonstrate differences in iron, phyllosilicate, and sulfate mineralogy and hematite grain size. Hematite is common across the ridge, and its detection in a gray outcrop suggest localized regions with coarse-grained hematite, which commonly forms from warm fluids. Broad XRD peaks for hematite in one sample below VRR and the abundance of FeO(T)in the amorphous component suggest the presence of nanocrystalline hematite and amorphous Fe oxides/oxyhydroxides. Well crystalline akaganeite and jarosite are present in two samples drilled from VRR, indicating at least limited alteration by acid-saline fluids. Collapsed nontronite is present below VRR, but samples from VRR contain phyllosilicate with d(001) = 9.6 angstrom, possibly from ferripyrophyllite or an acid-altered smectite. The most likely cementing agents creating the ridge are hematite and opaline silica. We hypothesize late diagenesis can explain much of the mineralogical variation on the ridge, where multiple fluid episodes with variable pH, salinity, and temperature altered the rocks, causing the precipitation and crystallization of phases that are not otherwise in equilibrium.
    • Motivations and methods for the analysis of multi-modality x-ray systems for explosives detection

      Carpenter, Joshua; Ding, Yijun; Hurlock, Ava; Coccarelli, David; Gregory, Christopher; Diallo, Souleymane O.; Ashok, Amit; Gehm, Michael E.; Greenberg, Joel A.; Univ Arizona (SPIE-INT SOC OPTICAL ENGINEERING, 2019-05-14)
      Transmission-based imaging and X-ray diffraction-based material analysis have largely developed independently. However, for a variety of applications ranging from in-vivo soft tissue analysis to concealed explosives detection, it is necessary to realize high-fidelity, spatially-resolved material discrimination. We therefore seek to understand to what degree transmission and X-ray diffraction (XRD) complement one another and can be implemented practically, particularly in the case of explosives detection in aviation security. Using a combination of simulated and experimental data, we identify the relative value of the X-ray signatures available to transmission and XRD measurements, and explore how the measurement fidelity can impact these results.