1,464 research outputs found
PIXEL 2010 - a Resume
The Pixel 2010 conference focused on semiconductor pixel detectors for
particle tracking/vertexing as well as for imaging, in particular for
synchrotron light sources and XFELs. The big LHC hybrid pixel detectors have
impressively started showing their capabilities. X-ray imaging detectors, also
using the hybrid pixel technology, have greatly advanced the experimental
possibilities for diiffraction experiments. Monolithic or semi-monolithic
devices like CMOS active pixels and DEPFET pixels have now reached a state such
that complete vertex detectors for RHIC and superKEKB are being built with
these technologies. Finally, new advances towards fully monolithic active pixel
detectors, featuring full CMOS electronics merged with efficient signal charge
collection, exploiting standard CMOS technologies, SOI and/or 3D integration,
show the path for the future. This r\'esum\'e attempts to extract the main
statements of the results and developments presented at this conference.Comment: 8 pages, 19 figures, conference summar
How to drive innovation? Analyzing the innovation process underlying the current program structure at Daimler FC think! tank
This thesis assesses the innovation programs offered by Daimler Finance and Controlling think!
tank with regard to the comprehensiveness of steps in the innovation process they cover. Innovation
has long been acknowledged as a main driver of competitiveness and growth, with researchers
highlighting the need to view innovation as a process. To support FC think! tank in finding possible
ways of innovation program improvement, an ideal-typical innovation process is derived from the
literature and compared to the structure of the FC think! tank programs, which are addressed in
more detail in a short case about the unit. It is recommended that the programs should possibly
extend their structure to support innovation teams more comprehensi
Space Astronomy for the mid-21st Century: Robotically Maintained Space Telescopes
The historical development of ground based astronomical telescopes leads us
to expect that space-based astronomical telescopes will need to be operational
for many decades. The exchange of scientific instruments in space will be a
prerequisite for the long lasting scientific success of such missions.
Operationally, the possibility to repair or replace key spacecraft components
in space will be mandatory. We argue that these requirements can be fulfilled
with robotic missions and see the development of the required engineering as
the main challenge. Ground based operations, scientifically and technically,
will require a low operational budget of the running costs. These can be
achieved through enhanced autonomy of the spacecraft and mission independent
concepts for the support of the software. This concept can be applied to areas
where the mirror capabilities do not constrain the lifetime of the mission.Comment: 4 pages, accepted in February 2012 for publication in A
XMM observation of 1RXS J180431.1-273932: a new M-type X-ray binary with a 494 s-pulse period neutron star?
Low-mass X-ray binaries are binary systems composed of a compact object and a
low-mass star. Recently, a new class of these systems, known as symbiotic
-ray binaries (with a neutron star with a M-type giant companion), has been
discovered. Here, we present long-duration observations of the
source 1RXS J180431.1-273932. Temporal and spectral analysis of the source was
performed along with a search for an optical counterpart. We used a
Lomb-Scargle periodogram analysis for the period search and evaluated the
confidence level using Monte-Carlo simulations. The source is characterized by
regular pulses so that it is most likely a neutron star. A modulation of
s (3 error) was found with a confidence level of 99%.
Evidence of variability is also present, since the data show a rate of change
in the signal of counts s hr. A longer
observation will be necessary in order to determine if the source shows any
periodic behavior. The spectrum can be described by a power law with photon
index and a Gaussian line at 6.6 keV. The X-ray flux in the
0.2--10 keV energy band is erg s cm. The
identification of an optical counterpart (possibly an M6III red-giant star with
an apparent visual magnitude of ) allows a conservative distance
of kpc to be estimated. Other possibilities are also discussed. Once
the distance was estimated, we got an -ray luminosity of L_X\ut<6\times
10^{34} erg s, which is consistent with the typical -ray luminosity
of a symbiotic LMXB system.Comment: in press on A&
\u3cem\u3eAgolohymena aspidocauda\u3c/em\u3e nov. gen., nov. spec., a Histophagous Freshwater Tetrahymenid Ciliate in the Family Deltopylidae (Ciliophora, Hymenostomatia), from Idaho (Northwest U.S.A.): Morphology, Ontogenesis and Molecular Phylogeny
Morphology, ontogeny and the molecular phylogeny of Agolohymena aspidocauda nov. gen., nov. spec., a new freshwater tetrahymenid ciliate from Idaho, U.S.A, are described. The ontogeny and histophagous mode of nutrition are similar to those of Deltopylum rhabdoides Fauré-Fremiet and Mugard, 1946. The new genus is placed with Deltopylum in the resurrected family Deltopylidae Song & Wilbert, 1989. We emend the diagnostic features of the family to include division by polytomy, right and left somatic kineties extending into the preoral suture, crook-shaped or sigmoid adoral membranelles 1 and 2, markedly reduced adoral membranelle 3 and a tetrahymenid silverline pattern. The main diagnostic features of the new genus are a disc-shaped caudal ciliary array and formation of two types of resting cysts, one smooth and the other bearing tangled tubular or cylindrical lepidosomes. Nuclear small subunit ribosomal RNA gene and mitochondrial cytochrome oxidase subunit 1 gene sequences place the new genus basal within the order Tetrahymenida, well separated from members of the family Tetrahymenidae (Lambornella and Tetrahymena) and also from other tetrahymenids (Colpidium, Dexiostoma, Glaucoma). The genetic divergences between this species and other genera in Tetrahymenida are large enough to suggest placement of the new genus in a separate family. This corroborates the morphological data, since the elaborate caudal ciliary array and the lepidosome-covered resting cyst of this species are not found in other Tetrahymenidae
Background study for the pn-CCD detector of CERN Axion Solar Telescope
The CERN Axion Solar Telescope (CAST) experiment searches for axions from the
Sun converted into photons with energies up to around 10 keV via the inverse
Primakoff effect in the high magnetic field of a superconducting Large Hadron
Collider (LHC) prototype magnet. A backside illuminated pn-CCD detector in
conjunction with an X-ray mirror optics is one of the three detectors used in
CAST to register the expected photon signal. Since this signal is very rare and
different background components (environmental gamma radiation, cosmic rays,
intrinsic radioactive impurities in the set-up, ...) entangle it, a detailed
study of the detector background has been undertaken with the aim to understand
and further reduce the background level of the detector. The analysis is based
on measured data taken during the Phase I of CAST and on Monte Carlo
simulations of different background components. This study will show that the
observed background level (at a rate of (8.00+-0.07)10^-5 counts/cm^2/s/keV
between 1 and 7 keV) seems to be dominated by the external gamma background due
to usual activities at the experimental site, while radioactive impurities in
the detector itself and cosmic neutrons could make just smaller contribution.Comment: Comments: 10 pages, 9 figures and images, submitted to Astroparticle
Physic
A New Comprehensive 2-D Model of the Point Spread Functions of the XMM-Newton EPIC Telescopes : Spurious Source Suppression and Improved Positional Accuracy
We describe here a new full 2-D parameterization of the PSFs of the three
XMM-Newton EPIC telescopes as a function of instrument, energy, off-axis angle
and azimuthal angle, covering the whole field-of-view of the three EPIC
detectors. It models the general PSF envelopes, the primary and secondary
spokes, their radial dependencies, and the large-scale azimuthal variations.
This PSF model has been constructed via the stacking and centering of a large
number of bright, but not significantly piled-up point sources from the full
field-of-view of each EPIC detector, and azimuthally filtering the resultant
PSF envelopes to form the spoke structures and the gross azimuthal shapes
observed. This PSF model is available for use within the XMM-Newton Science
Analysis System via the usage of Current Calibration Files XRTi_XPSF_0011.CCF
and later versions. Initial source-searching tests showed substantial
reductions in the numbers of spurious sources being detected in the wings of
bright point sources. Furthermore, we have uncovered a systematic error in the
previous PSF system, affecting the entire mission to date, whereby returned
source RA and Dec values are seen to vary sinusoidally about the true position
(amplitude ~0.8") with source azimuthal position. The new PSF system is now
available and is seen as a major improvement with regard to the detection of
spurious sources. The new PSF also largely removes the discovered astrometry
error and is seen to improve the positional accuracy of EPIC. The modular
nature of the PSF system allows for further refinements in the future.Comment: Accepted for publication in A&A. 15 pages, 13 figures (some of
reduced quality). A full-resolution version is available at
http://www.star.le.ac.uk/~amr30/amr_PSFpaper.pd
Imaging Molecules from Within: Ultra-fast, {\AA}ngstr\"om Scale Structure Determination of Molecules via Photoelectron Holography using Free Electron Lasers
A new scheme based on (i) upcoming brilliant X-ray Free Electron Laser (FEL)
sources, (ii) novel energy and angular dispersive, large-area electron imagers
and (iii) the well-known photoelectron holography is elaborated that provides
time-dependent three-dimensional structure determination of small to medium
sized molecules with {\AA}ngstr\"om spatial and femtosecond time resolution.
Inducing molecular dynamics, wave-packet motion, dissociation, passage through
conical intersections or isomerization by a pump pulse this motion is
visualized by the X-ray FEL probe pulse launching keV photoelectrons within few
femtoseconds from specific and well-defined sites, deep core levels of
individual atoms, inside the molecule. On their way out the photoelectrons are
diffracted generating a hologram on the detector that encodes the molecular
structure at the instant of photoionization, thus providing 'femtosecond
snapshot images of the molecule from within'. Detailed calculations in various
approximations of increasing sophistication are presented and three-dimensional
retrieval of the spatial structure of the molecule with {\AA}ngstr\"om spatial
resolution is demonstrated. Due to the large photo-absorption cross sections
the method extends X-ray diffraction based, time-dependent structure
investigations envisioned at FELs to new classes of samples that are not
accessible by any other method. Among them are dilute samples in the gas phase
such as aligned, oriented or conformer selected molecules, ultra-cold ensembles
and/or molecular or cluster objects containing mainly light atoms that do not
scatter X-rays efficiently.Comment: 18 pages, 11 figure
Background Simulations of the Wide Field Imager of the ATHENA X-Ray Observatory
The ATHENA X-ray Observatory-IXO is a planned multinational orbiting X-ray
observatory with a focal length of 11.5m. ATHENA aims to perform pointed
observations in an energy range from 0.1 keV to 15 keV with high sensitivity.
For high spatial and timing resolution imaging and spectroscopic observations
the 640x640 pixel^2 large DePFET-technology based Wide field Imager (WFI) focal
plane detector, providing a field of view of 18 arcsec will be the main
detector. Based on the actual mechanics, thermal and shielding design we
present estimates for the WFI cosmic ray induced background obtained by the use
of Monte-Carlo simulations and possible background reduction measures.Comment: IEEE NSS MIC Conference 2011, Valencia, Spai
Science with the EXTraS Project: Exploring the X-ray Transient and variable Sky
The EXTraS project (Exploring the X-ray Transient and variable Sky) will
characterise the temporal behaviour of the largest ever sample of objects in
the soft X-ray range (0.1-12 keV) with a complex, systematic and consistent
analysis of all data collected by the European Photon Imaging Camera (EPIC)
instrument onboard the ESA XMM-Newton X-ray observatory since its launch. We
will search for, and characterize variability (both periodic and aperiodic) in
hundreds of thousands of sources spanning more than nine orders of magnitude in
time scale and six orders of magnitude in flux. We will also search for fast
transients, missed by standard image analysis. Our analysis will be completed
by multiwavelength characterization of new discoveries and phenomenological
classification of variable sources. All results and products will be made
available to the community in a public archive, serving as a reference for a
broad range of astrophysical investigations.Comment: 4 pages, 1 figure. Refereed Proceeding of "The Universe of Digital
Sky Surveys" conference held at the INAF - Observatory of Capodimonte,
Naples, on 25th-28th November 2014, to be published in the Astrophysics and
Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo,
Iodic
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