19,231 research outputs found
Infrastructure for Detector Research and Development towards the International Linear Collider
The EUDET-project was launched to create an infrastructure for developing and
testing new and advanced detector technologies to be used at a future linear
collider. The aim was to make possible experimentation and analysis of data for
institutes, which otherwise could not be realized due to lack of resources. The
infrastructure comprised an analysis and software network, and instrumentation
infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture
Perspectives of Imaging of Single Protein Molecules with the Present Design of the European XFEL. - Part I - X-ray Source, Beamlime Optics and Instrument Simulations
The Single Particles, Clusters and Biomolecules (SPB) instrument at the
European XFEL is located behind the SASE1 undulator, and aims to support
imaging and structure determination of biological specimen between about 0.1
micrometer and 1 micrometer size. The instrument is designed to work at photon
energies from 3 keV up to 16 keV. This wide operation range is a cause for
challenges to the focusing optics. In particular, a long propagation distance
of about 900 m between x-ray source and sample leads to a large lateral photon
beam size at the optics. The beam divergence is the most important parameter
for the optical system, and is largest for the lowest photon energies and for
the shortest pulse duration (corresponding to the lowest charge). Due to the
large divergence of nominal X-ray pulses with duration shorter than 10 fs, one
suffers diffraction from mirror aperture, leading to a 100-fold decrease in
fluence at photon energies around 4 keV, which are ideal for imaging of single
biomolecules. The nominal SASE1 output power is about 50 GW. This is very far
from the level required for single biomolecule imaging, even assuming perfect
beamline and focusing efficiency. Here we demonstrate that the parameters of
the accelerator complex and of the SASE1 undulator offer an opportunity to
optimize the SPB beamline for single biomolecule imaging with minimal
additional costs and time. Start to end simulations from the electron injector
at the beginning of the accelerator complex up to the generation of diffraction
data indicate that one can achieve diffraction without diffraction with about
0.5 photons per Shannon pixel at near-atomic resolution with 1e13 photons in a
4 fs pulse at 4 keV photon energy and in a 100 nm focus, corresponding to a
fluence of 1e23 ph/cm^2. This result is exemplified using the RNA Pol II
molecule as a case study
Random on-board pixel sampling (ROPS) X-ray Camera
Recent advances in compressed sensing theory and algorithms offer new
possibilities for high-speed X-ray camera design. In many CMOS cameras, each
pixel has an independent on-board circuit that includes an amplifier, noise
rejection, signal shaper, an analog-to-digital converter (ADC), and optional
in-pixel storage. When X-ray images are sparse, i.e., when one of the following
cases is true: (a.) The number of pixels with true X-ray hits is much smaller
than the total number of pixels; (b.) The X-ray information is redundant; or
(c.) Some prior knowledge about the X-ray images exists, sparse sampling may be
allowed. Here we first illustrate the feasibility of random on-board pixel
sampling (ROPS) using an existing set of X-ray images, followed by a discussion
about signal to noise as a function of pixel size. Next, we describe a possible
circuit architecture to achieve random pixel access and in-pixel storage. The
combination of a multilayer architecture, sparse on-chip sampling, and
computational image techniques, is expected to facilitate the development and
applications of high-speed X-ray camera technology.Comment: 9 pages, 6 figures, Presented in 19th iWoRI
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