The morphology of micrometre-size particulate matter is of critical importance in fields ranging from toxicology to climate science, yet these properties are surprisingly difficult to measure in the ...particles' native environment. Electron microscopy requires collection of particles on a substrate; visible light scattering provides insufficient resolution; and X-ray synchrotron studies have been limited to ensembles of particles. Here we demonstrate an in situ method for imaging individual sub-micrometre particles to nanometre resolution in their native environment, using intense, coherent X-ray pulses from the Linac Coherent Light Source free-electron laser. We introduced individual aerosol particles into the pulsed X-ray beam, which is sufficiently intense that diffraction from individual particles can be measured for morphological analysis. At the same time, ion fragments ejected from the beam were analysed using mass spectrometry, to determine the composition of single aerosol particles. Our results show the extent of internal dilation symmetry of individual soot particles subject to non-equilibrium aggregation, and the surprisingly large variability in their fractal dimensions. More broadly, our methods can be extended to resolve both static and dynamic morphology of general ensembles of disordered particles. Such general morphology has implications in topics such as solvent accessibilities in proteins, vibrational energy transfer by the hydrodynamic interaction of amino acids, and large-scale production of nanoscale structures by flame synthesis.
Abstract
An x-ray imager is being developed for use in diffraction-limited synchrotron rings and continuous wave free electron lasers. The imager is named CoRDIA (COntinuous Readout Digitising Imager ...Array) and aims at achieving continuous operation at a frame rate in excess of 100kHz. Other goals include single-photon sensitivity at 12 keV (or below), a full well in excess of 10k photon/pixel/image, and a 100μm pixel pitch. The detector ASIC will be compatible with multiple sensor materials to cover different energy ranges. Exploratory prototypes of the readout ASIC (basic circuital blocks) have been manufactured in TSMC 65nm technology: they are presently under test.
SPI: The spectrometer aboard INTEGRAL Vedrenne, G.; Roques, J.-P.; Schönfelder, V. ...
Astronomy & astrophysics,
11/2003, Letnik:
411, Številka:
1
Journal Article
Recenzirano
Odprti dostop
SPI is a high spectral resolution gamma-ray telescope on board the ESA mission INTEGRAL (International Gamma Ray Astrophysics Laboratory). It consists of an array of 19 closely packed germanium ...detectors surrounded by an active anticoincidence shield of BGO. The imaging capabilities of the instrument are obtained with a tungsten coded aperture mask located 1.7 m from the Ge array. The fully coded field-of-view is $16\deg$, the partially coded field of view amounts to $31\deg$, and the angular resolution is $2.5\deg$. The energy range extends from 20 keV to 8 MeV with a typical energy resolution of 2.5 keV at 1.3 MeV. Here we present the general concept of the instrument followed by a brief description of each of the main subsystems. INTEGRAL was successfully launched in October 2002 and SPI is functioning extremely well.
The focal-plane module is the key component of the DEPFET sensor with signal compression (DSSC) mega-pixel X-ray imager and handles the data of 128 <inline-formula> <tex-math ...notation="LaTeX">\times512 </tex-math></inline-formula> pixels. We report on assembly-related aspects, discuss the experimental investigation of bonding behavior of different adhesives, and present the metrology and electrical test results of the production. The module consists of two silicon (Si) sensors with flip-chip connected CMOS integrated circuits, a Si-heat spreader, a low-temperature co-fired ceramics circuit board, and a molybdenum frame. A low-modulus urethane-film adhesive fills the gaps between on-board components and frame. It is also used between board and heat spreader, reduces the misfit strain, and minimizes the module warpage very efficiently. The heat spreader reduces the on-board temperature gradient by about one order of magnitude. The placement precision of the bare modules to each other and the frame is characterized by a standard deviation below 10 and 65 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>, respectively. The displacement due to the in-plane rotation and vertical tilting errors remains below 80 and 50 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>, respectively. The deflection of the sensor plane shows a mean value below 30 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> with a standard deviation below 15 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>. Less than 4% of the application-specified integrated circuits (ASICs) exhibit a malfunction. More than two-thirds of the sensors have a maximum leakage current below 1 <inline-formula> <tex-math notation="LaTeX">\mu \text{A} </tex-math></inline-formula>.
The Nuclear Compton Telescope (NCT) is a balloon-borne Compton telescope designed for the study of astrophysical sources in the soft gamma-ray regime (200 keV-20 MeV). NCT's 10 high-purity germanium ...crossed-strip detectors measure the deposited energies and three-dimensional positions of gamma-ray interactions in the sensitive volume, and this information is used to restrict the initial photon to a circle on the sky using the Compton scatter technique. Thus NCT is able to perform spectroscopy, imaging, and polarization analysis on soft gamma-ray sources. NCT is one of the next generation of Compton telescopes--the so-called compact Compton telescopes (CCTs)--which can achieve effective areas comparable to the Imaging Compton Telescope's with an instrument that is a fraction of the size. The Crab Nebula was the primary target for the second flight of the NCT instrument, which occurred on 2009 May 17 and 18 in Fort Sumner, New Mexico. Analysis of 29.3 ks of data from the flight reveals an image of the Crab at a significance of 4 Delta *s. This is the first reported detection of an astrophysical source by a CCT.
SPI/INTEGRAL in-flight performance Roques, J. P.; Schanne, S.; von Kienlin, A. ...
Astronomy & astrophysics,
11/2003, Letnik:
411, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The SPI instrument has been launched on-board the INTEGRAL observatory on October 17, 2002. SPI is a spectrometer devoted to the sky observation in the 20 keV–8 MeV energy range using 19 germanium ...detectors. The performance of the cryogenic system is nominal and allows to cool the 19 kg of germanium down to 85 K with a comfortable margin. The energy resolution of the whole camera is 2.5 keV at 1.1 MeV. This resolution degrades with time due to particle irradiation in space. We show that the annealing process allows the recovery of the initial performance. The anticoincidence shield works as expected, with a low threshold at 75 keV, reducing the GeD background by a factor of 20. The digital front-end electronics system allows the perfect alignement in time of all the signals as well as the optimisation of the dead time (12%). We demonstrate that SPI is able to map regions as complex as the galactic plane. The obtained spectrum of the Crab nebula validates the present version of our response matrix. The 3σ sensitivity of the instrument at 1 MeV is $8\times10^{-7}$ ph cm-2 s-1 keV-1 for the continuum and $3\times10^{-5}$ ph cm-2 s-1 for narrow lines.
X-ray free-electron lasers have enabled new approaches to the structural determination of protein crystals that are too small or radiation-sensitive for conventional analysis
. For sufficiently short ...pulses, diffraction is collected before significant changes occur to the sample, and it has been predicted that pulses as short as 10 fs may be required to acquire atomic-resolution structural information
. Here, we describe a mechanism unique to ultrafast, ultra-intense X-ray experiments that allows structural information to be collected from crystalline samples using high radiation doses without the requirement for the pulse to terminate before the onset of sample damage. Instead, the diffracted X-rays are gated by a rapid loss of crystalline periodicity, producing apparent pulse lengths significantly shorter than the duration of the incident pulse. The shortest apparent pulse lengths occur at the highest resolution, and our measurements indicate that current X-ray free-electron laser technology
should enable structural determination from submicrometre protein crystals with atomic resolution.
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