B16-Test Beamline
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Abstract: The X-ray birefringence imaging (XBI) technique, first reported in 2014, is a sensitive method for spatially resolved mapping of the local orientational properties of anisotropic materials. In the case of organic materials, the technique may be applied to study the orientational properties of individual molecules and/or bonds, including the study of changes in molecular orientations associated with order–disorder phase transitions and characterization of phase transitions in liquid crystalline materials. This chapter presents a basic introduction to the XBI technique, giving a qualitative description of the fundamentals of the technique and discussing experimental aspects of the measurement of XBI data. Several examples are presented to highlight the application of the technique to study the orientational properties of molecules in organic materials.
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Jul 2020
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B16-Test Beamline
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Open Access
Abstract: A two-dimensional array of compound refractive lenses (2D array of CRLs) designed for hard X-ray imaging with a 3.5 mm2 large field of view is presented. The array of CRLs consists of 2D polymer biconcave parabolic 34 × 34 multi-lenses fabricated via deep X-ray lithography. The developed refractive multi-lens array was applied for sub-pixel resolution scanning transmission X–ray microscopy; a raster scan with only 55 × 55 steps provides a 3.5 megapixel image. The optical element was experimentally characterized at the Diamond Light Source at 34 keV. An array of point foci with a 55 µm period and an average size of ca. 2.1 µm × 3.6 µm was achieved. In comparison with the conventional scanning transmission microscopy using one CRL, sub-pixel resolution scanning transmission hard X-ray microscopy enables a large field of view and short scanning time while keeping the high spatial resolution.
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Jun 2020
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B16-Test Beamline
Detectors
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Abstract: One of the major limitations of XAS experiment at synchrotron facilities is the performance of the detectors. In order to be able to measure more challenging samples and to cope with the very high photon flux of the current and future (diffraction limited) sources technological developments of detectors are necessary. This paper reports on the construction and characterization of a monolithic nineteen channel germanium detector demonstrator fitted with CMOS preamplifiers. The detector was characterized in the lab with radioactive sources and with the X-ray synchrotron beam. Characteristics such as energy resolution, linearity, counting rate capabilities, and stability of the detector were thoroughly evaluated. In addition, it was proved that by using an advanced pulse processor such as Xspress4 it was possible to improve the performance of the detector system by eliminating the cross talk among channels and by suppressing the charge shared events. This work could pave the way to enhanced germanium fluorescence detectors for high throughput X-ray spectroscopy.
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Jun 2020
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B16-Test Beamline
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Diamond Proposal Number(s):
[20428, 24513]
Open Access
Abstract: Nylon-12 is an important structural polymer in wide use in the form of fibres and bulk structures. Fused filament fabrication (FFF) is an extrusion-based additive manufacturing (AM) method for rapid prototyping and final product manufacturing of thermoplastic polymer objects. The resultant microstructure of FFF-produced samples is strongly affected by the cooling rates and thermal gradients experienced across the part. The crystallisation behaviour during cooling and solidification influences the micro- and nano-structure, and deserves detailed investigation. A commercial Nylon-12 filament and FFF-produced Nylon-12 parts were studied by differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) to examine the effect of cooling rates under non-isothermal crystallisation conditions on the microstructure and properties. Slower cooling rates caused more perfect crystallite formation, as well as alteration to the thermal properties.
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May 2020
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B16-Test Beamline
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Diamond Proposal Number(s):
[20103]
Open Access
Abstract: Highly efficient scintillation crystals with short decay times are indispensable for improving the performance of numerous detection and imaging instruments that use- X-rays, gamma-quanta, ionising particles or neutrons. Halide perovskites emerged recently as very promising materials for detection of ionising radiation that motivated further exploration of the materials. In this work, we report on excellent scintillation properties of CsPbBr3 crystals when cooled to cryogenic temperatures. The temperature dependence of luminescence spectra, decay kinetics and light yield under excitation with X-rays and α-particles was investigated. It is shown that the observed changes of spectral and kinetic characteristics of the crystal with temperature can be consistently explained by radiative decay of free excitons, bound and trapped excitons as well as electron-hole pairs originating from their disintegration. It has been found that the crystal exhibits a fast decay time constant of 1 ns at 7 K. The scintillation light yield of CsPbBr3 at 7 K is assessed to be 50,000 ± 10,000 ph/MeV at excitation with 12 keV X-rays and 109,000 ± 22,000 ph/MeV at excitation with α-particles of 241Am. This finding places CsPbBr3 in an excellent position for the development of a new generation of cryogenic, efficient scintillation detectors with nanosecond response time, marking a step-change in opportunities for scintillator-based applications.
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May 2020
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B16-Test Beamline
B18-Core EXAFS
Optics
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Open Access
Abstract: An ≈4 nm FeCrNi film, deposited on a Ru/B4C multilayer (ML), is used to study cathodic hydrogen charging in electrolyte. A thin film on a ML allows obtaining precise quantitative information on surface metal composition and oxidation state using the X‐ray standing wave technique combined with near‐edge X‐ray absorption spectroscopy. The metal composition is found being close to the composition of stainless steel (SS) 304, and, as for bulk steel, the outer 2 nm passive layer, consisting of oxidized iron and chromium, is depleted of nickel. Overall, it is found that the film represented a useful replica of the surface of bulk steel. Following exposure to 0.1 m KCl electrolyte at −0.6 V versus Ag/AgCl, 11.3 (±3)% swelling of the film by hydrogen absorption is observed. The estimated absorbed amount is exceeding reported bulk absorption under similar conditions by more than an order of magnitude. Strong hydrogen absorption appears to be enabled by the 2D character of the thin film, i.e., a significantly lower associated strain energy compared with bulk absorption. The strong surface swelling is suggested to be related to the lowering of the pitting corrosion resistance of SS surfaces reported following hydrogen exposure.
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Apr 2020
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B16-Test Beamline
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Anna
Turyanskaya
,
Mirjam
Rauwolf
,
Vanessa
Pichler
,
Rolf
Simon
,
Manfred
Burghammer
,
Oliver J. L.
Fox
,
Kawal
Sawhney
,
Jochen G.
Hofstaetter
,
Andreas
Roschger
,
Paul
Roschger
,
Peter
Wobrauschek
,
Christina
Streli
Diamond Proposal Number(s):
[16260]
Open Access
Abstract: Gadolinium-based contrast agents (GBCAs) are frequently used in patients undergoing magnetic resonance imaging. In GBCAs gadolinium (Gd) is present in a bound chelated form. Gadolinium is a rare-earth element, which is normally not present in human body. Though the blood elimination half-life of contrast agents is about 90 minutes, recent studies demonstrated that some tissues retain gadolinium, which might further pose a health threat due to toxic effects of free gadolinium. It is known that the bone tissue can serve as a gadolinium depot, but so far only bulk measurements were performed. Here we present a summary of experiments in which for the first time we mapped gadolinium in bone biopsy from a male patient with idiopathic osteoporosis (without indication of renal impairment), who received MRI 8 months prior to biopsy. In our studies performed by means of synchrotron radiation induced micro- and submicro-X-ray fluorescence spectroscopy (SR-XRF), gadolinium was detected in human cortical bone tissue. The distribution of gadolinium displays a specific accumulation pattern. Correlation of elemental maps obtained at ANKA synchrotron with qBEI images (quantitative backscattered electron imaging) allowed assignment of Gd structures to the histological bone structures. Follow-up beamtimes at ESRF and Diamond Light Source using submicro-SR-XRF allowed resolving thin Gd structures in cortical bone, as well as correlating them with calcium and zinc.
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Apr 2020
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B16-Test Beamline
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M.
Mironova
,
K.
Metodiev
,
P.
Allport
,
I.
Berdalovic
,
Daniela
Bortoletto
,
C.
Buttar
,
R.
Cardella
,
V.
Dao
,
M.
Dyndal
,
P.
Freeman
,
L.
Flores Sanz De Acedo
,
L.
Gonella
,
T.
Kugathasan
,
H.
Pernegger
,
F.
Piro
,
R.
Plackett
,
P.
Riedler
,
A.
Sharma
,
E. J.
Schioppa
,
I.
Shipsey
,
C.
Solans Sanchez
,
W.
Snoeys
,
H.
Wennlöf
,
D.
Weatherill
,
D.
Wood
,
S.
Worm
Diamond Proposal Number(s):
[2206]
Abstract: This paper outlines the results of investigations into the effects of radiation damage in the mini-MALTA depleted monolithic pixel sensor prototype. Measurements were carried out at Diamond Light Source using a micro-focus X-ray beam, which scanned across the surface of the device in 2
μm
steps. This allowed the in-pixel photon response to be measured directly with high statistics. Three pixel design variations were considered: one with the standard continuous
n−
layer layout and front-end, and extra deep p-well and
n−
gap designs with a modified front-end. Five chips were measured: one unirradiated, one neutron irradiated, and three proton irradiated. The standard design showed a decrease of 12% in pixel response after irradiation to 1e15
neq∕cm2
. For the two new designs the pixel response did not decrease significantly after irradiation. A decrease of pixel response at high biasing voltages was observed. The charge sharing in the chip was quantified and found to be in agreement with expectations.
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Mar 2020
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B16-Test Beamline
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Diamond Proposal Number(s):
[2206]
Abstract: The MALTA team is developing the MALTA chip, a depleted monolithic active pixel sensor (DMAPS) implemented in the TowerJazz 180 nm modified CMOS process for tracking applications in high energy particle physics experiments such as the ATLAS experiment at the LHC . At the INFIERI school in Wuhan, China, I presented results on what was then the latest prototype of the chip, the MiniMALTA. So far measurements have shown promising that suggest that the chip is operational after irradiation doses comparable to those predicted for the outer pixel layers of the proposed inner tracker (ITk) upgrade in ATLAS.
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Mar 2020
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B16-Test Beamline
Detectors
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Leonardo
Abbene
,
Fabio
Principato
,
Gaetano
Gerardi
,
Antonino
Buttacavoli
,
Donato
Cascio
,
Manuele
Bettelli
,
Nicola
Sarzi Amade
,
Paul
Seller
,
Matthew C.
Veale
,
Oliver
Fox
,
Kawal
Sawhney
,
Silvia
Zanettini
,
Elio
Tomarchio
,
Andrea
Zappettini
Diamond Proposal Number(s):
[20545]
Abstract: In this work, the spectroscopic performances of new cadmium–zinc–telluride (CZT) pixel detectors recently developed at IMEM-CNR of Parma (Italy) are presented. Sub-millimetre arrays with pixel pitch less than 500 µm, based on boron oxide encapsulated vertical Bridgman grown CZT crystals, were fabricated. Excellent room-temperature performance characterizes the detectors even at high-bias-voltage operation (9000 V cm−1), with energy resolutions (FWHM) of 4% (0.9 keV), 1.7% (1 keV) and 1.3% (1.6 keV) at 22.1, 59.5 and 122.1 keV, respectively. Charge-sharing investigations were performed with both uncollimated and collimated synchrotron X-ray beams with particular attention to the mitigation of the charge losses at the inter-pixel gap region. High-rate measurements demonstrated the absence of high-flux radiation-induced polarization phenomena up to 2 × 106 photons mm−2 s−1. These activities are in the framework of an international collaboration on the development of energy-resolved photon-counting systems for high-flux energy-resolved X-ray imaging.
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Mar 2020
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