84 research outputs found
Optimization of radiation hardness and charge collection of edgeless silicon pixel sensors for photon science
Recent progress in active-edge technology of silicon sensors enables the
development of large-area tiled silicon pixel detectors with small dead space
between modules by utilizing edgeless sensors. Such technology has been proven
in successful productions of ATLAS and Medipix-based silicon pixel sensors by a
few foundries. However, the drawbacks of edgeless sensors are poor radiation
hardness for ionizing radiation and non-uniform charge collection by edge
pixels. In this work, the radiation hardness of edgeless sensors with different
polarities has been investigated using Synopsys TCAD with X-ray
radiation-damage parameters implemented. Results show that if no conventional
guard ring is present, none of the current designs are able to achieve a high
breakdown voltage (typically < 30 V) after irradiation to a dose of ~10 MGy. In
addition, a charge-collection model has been developed and was used to
calculate the charges collected by the edge pixels of edgeless sensors when
illuminated with X-rays. The model takes into account the electric field
distribution inside the pixel sensor, the absorption of X-rays, drift and
diffusion of electrons and holes, charge sharing effect, and threshold settings
in ASICs. It is found that the non-uniform charge collection of edge pixels is
caused by the strong bending of electric field and the non-uniformity depends
on bias voltage, sensor thickness and distance from active edge to the last
pixel ("edge space"). In particular, the last few pixels close to the active
edge of the sensor are not sensitive to low-energy X-rays (< 10 keV) especially
for sensors with thicker Si and smaller edge space. The results from the model
calculation have been compared to measurements and good agreement was obtained.
The model has been used to optimize the edge design.Comment: 12 pages, 8 figure
Detector developments for photon science at DESY
The past, current and planned future developments of X-ray imagers in the Photon-Science Detector Group at DESY-Hamburg is presented. the X-ray imagers are custom developed and tailored to the different X-ray sources in Hamburg, including the storage ring PETRA III/IV; the VUV-soft X-ray free electron laser FLASH, and the European Free-Electron Laser. Each source puts different requirements on the X-ray detectors, which is described in detail, together with the technical solutions implemented
The Adaptive Gain Integrating Pixel Detector at the European XFEL
The Adaptive Gain Integrating Pixel Detector (AGIPD) is an x-ray imager,
custom designed for the European x-ray Free-Electron Laser (XFEL). It is a
fast, low noise integrating detector, with an adaptive gain amplifier per
pixel. This has an equivalent noise of less than 1 keV when detecting single
photons and, when switched into another gain state, a dynamic range of more
than 10 photons of 12 keV. In burst mode the system is able to store 352
images while running at up to 6.5 MHz, which is compatible with the 4.5 MHz
frame rate at the European XFEL. The AGIPD system was installed and
commissioned in August 2017, and successfully used for the first experiments at
the Single Particles, Clusters and Biomolecules (SPB) experimental station at
the European XFEL since September 2017. This paper describes the principal
components and performance parameters of the system.Comment: revised version after peer revie
R&D Paths of Pixel Detectors for Vertex Tracking and Radiation Imaging
This report reviews current trends in the R&D of semiconductor pixellated
sensors for vertex tracking and radiation imaging. It identifies requirements
of future HEP experiments at colliders, needed technological breakthroughs and
highlights the relation to radiation detection and imaging applications in
other fields of science.Comment: 17 pages, 2 figures, submitted to the European Strategy Preparatory
Grou
Megapixels @ Megahertz -- The AGIPD High-Speed Cameras for the European XFEL
The European XFEL is an extremely brilliant Free Electron Laser Source with a
very demanding pulse structure: trains of 2700 X-Ray pulses are repeated at 10
Hz. The pulses inside the train are spaced by 220 ns and each one contains up
to photons of 12.4 keV, while being fs in length. AGIPD,
the Adaptive Gain Integrating Pixel Detector, is a hybrid pixel detector
developed by DESY, PSI, and the Universities of Bonn and Hamburg to cope with
these properties. It is a fast, low noise integrating detector, with single
photon sensitivity (for keV) and a large dynamic
range, up to photons at 12.4 keV. This is achieved with a charge
sensitive amplifier with 3 adaptively selected gains per pixel. 352 images can
be recorded at up to 6.5 MHz and stored in the in-pixel analogue memory and
read out between pulse trains. The core component of this detector is the AGIPD
ASIC, which consists of pixels of . Control of the ASIC's image acquisition and analogue readout is
via a command based interface. FPGA based electronic boards, controlling ASIC
operation, image digitisation and 10 GE data transmission interface AGIPD
detectors to DAQ and control systems. An AGIPD 1 Mpixel detector has been
installed at the SPB experimental station in August 2017, while a second one is
currently commissioned for the MID endstation. A larger (4 Mpixel) AGIPD
detector and one to employ Hi-Z sensor material to efficiently register photons
up to keV are currently under construction.Comment: submitted to the proceedings of the ULITIMA 2018 conference, to be
published in NIM
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CAMP@FLASH: an end-station for imaging, electron- and ion-spectroscopy, and pumpâprobe experiments at the FLASH free-electron laser
The non-monochromatic beamline BL1 at the FLASH free-electron laser facility at DESY was upgraded with new transport and focusing optics, and a new permanent end-station, CAMP, was installed. This multi-purpose instrument is optimized for electron- and ion-spectroscopy, imaging and pumpâprobe experiments at free-electron lasers. It can be equipped with various electron- and ion-spectrometers, along with large-area single-photon-counting pnCCD X-ray detectors, thus enabling a wide range of experiments from atomic, molecular, and cluster physics to material and energy science, chemistry and biology. Here, an overview of the layout, the beam transport and focusing capabilities, and the experimental possibilities of this new end-station are presented, as well as results from its commissioning
A MHz X-ray diffraction set-up for dynamic compression experiments in the diamond anvil cell
An experimental platform for dynamic diamond anvil cell (dDAC) research has been developed at the High Energy Density (HED) Instrument at the European X-ray Free Electron Laser (European XFEL). Advantage was taken of the high repetition rate of the European XFEL (up to 4.5â
MHz) to collect pulse-resolved MHz X-ray diffraction data from samples as they are dynamically compressed at intermediate strain rates (â€103â
sâ1), where up to 352 diffraction images can be collected from a single pulse train. The set-up employs piezo-driven dDACs capable of compressing samples in â„340â
”s, compatible with the maximum length of the pulse train (550â
”s). Results from rapid compression experiments on a wide range of sample systems with different X-ray scattering powers are presented. A maximum compression rate of 87â
TPaâ
sâ1 was observed during the fast compression of Au, while a strain rate of âŒ1100â
sâ1 was achieved during the rapid compression of N2 at 23â
TPaâ
sâ1
Segmented flow generator for serial crystallography at the European X-ray free electron laser
Serial femtosecond crystallography (SFX) with X-ray free electron lasers (XFELs) allows structure determination of membrane proteins and time-resolved crystallography. Common liquid sample delivery continuously jets the protein crystal suspension into the path of the XFEL, wasting a vast amount of sample due to the pulsed nature of all current XFEL sources. The European XFEL (EuXFEL) delivers femtosecond (fs) X-ray pulses in trains spaced 100 ms apart whereas pulses within trains are currently separated by 889 ns. Therefore, continuous sample delivery via fast jets wastes >99% of sample. Here, we introduce a microfluidic device delivering crystal laden droplets segmented with an immiscible oil reducing sample waste and demonstrate droplet injection at the EuXFEL compatible with high pressure liquid delivery of an SFX experiment. While achieving ~60% reduction in sample waste, we determine the structure of the enzyme 3-deoxy-D-manno-octulosonate-8-phosphate synthase from microcrystals delivered in droplets revealing distinct structural features not previously reported
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