| 1. |
- Aad, G, et al.
(författare)
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- 2015
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swepub:Mat__t
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| 2. |
- Echelmeier, A., et al.
(författare)
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Segmented flow generator for serial crystallography at the European X-ray free electron laser
- 2020
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Ingår i: Nature Communications. - : Nature Research. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 3. |
- Allahgholi, A., et al.
(författare)
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Front end ASIC for AGIPD, a high dynamic range fast detector for the European XFEL
- 2016
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Ingår i: Journal of Instrumentation. - 1748-0221 .- 1748-0221. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- The Adaptive Gain Integrating Pixel Detector (AGIPD) is a hybrid pixel X-ray detector for the European-XFEL. One of the detector's important parts is the radiation tolerant front end ASIC fulfilling the European-XFEL requirements: high dynamic range-from sensitivity to single 12.5keV-photons up to 104 photons. It is implemented using the dynamic gain switching technique with three possible gains of the charge sensitive preamplifier. Each pixel can store up to 352 images in memory operated in random-access mode at >= 4.5MHz frame rate. An external vetoing may be applied to overwrite unwanted frames.
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| 4. |
- Allahgholi, A., et al.
(författare)
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The AGIPD 1.0 ASIC : Random access high frame rate, high dynamic range X-ray camera readout for the European XFEL
- 2015
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Ingår i: 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2015. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467398626
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Konferensbidrag (refereegranskat)abstract
- 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 1012 photons of 12.4 keV, while being ≤ 100 fs in length. AGIPD (Adaptive Gain Integrating Pixel Detector) is a hybrid 1M-pixel detector developed by DESY, PSI, and the Universities of Bonn and Hamburg to cope with these properties. Thus the readout ASIC has to provide not only single photon sensitivity and a dynamic range ≳ 104 photons/pixel in the same image but also a memory for as many images of a pulse train as possible for delayed readout prior to the next train. The AGIPD 1.0 ASIC uses a 130 nm CMOS technology and radiation tolerant techniques to withstand the radiation damage incurred by the high impinging photon flux. Each ASIC contains 64 × 64 pixels of 200μmχ200μm. The circuit of each pixel contains a charge sensitive preamplifier with threefold switchable gain, a discriminator for an adaptive gain selection, and a correlated double sampling (CDS) stage to remove reset and low-frequency noise components. The output of the CDS, as well as the dynamically selected gain is sampled in a capacitor-based analogue memory for 352 samples, which occupies about 80% of a pixels area. For readout each pixel features a charge sensitive buffer. A control circuit with a command based interface provides random access to the memory and controls the row-wise readout of the data via multiplexers to four differential analogue ports. The AGIPD 1.0 full scale ASIC has been received back from the foundry in fall of 2013. Since then it has been extensively characterised also with a sensor as a single chip and in 2 × 8-chip modules for the AGIPD 1 Mpix detector. We present the design of the AGIPD 1.0 ASIC along with supporting results, also from beam tests at PETRA III and APS, and show changes incorporated in the recently taped out AGIPD 1.1 ASIC upgrade.
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| 5. |
- Mezza, D., et al.
(författare)
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Characterization of the AGIPD1.1 readout chip and improvements with respect to AGIPD1.0
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 945
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Tidskriftsartikel (refereegranskat)abstract
- AGIPD, the Adaptive Gain Integrating Pixel Detector, is a hybrid detector with a frame rate of 4.5 MHz, a dynamic range up to 104⋅ 12.4 keV photons, as well as single photon resolution, developed for the European XFEL (Eu.XFEL). The final 1 Mpixel detector system consists of 16 tiled modules each one with 16 readout chips. The single ASIC is 64 x 64 pixels, each with a size of 200 x 200 μm2. Each pixel can store up to 352 images. This work is focused on the characterization of AGIPD1.1, the second version of the full scale ASIC, and the improvements with respect to AGIPD1.0. From the measurements presented in this paper we show that the flaws observed in AGIPD1.0 (i.e. ghosting, crosstalk, slow readout speed) have been fixed in AGIPD1.1. In addition the main performance parameters such as noise, dynamic range and so on were measured for the new version of the ASIC and will be summarized.
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| 6. |
- Trunk, Ulrich, et al.
(författare)
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AGIPD : A multi megapixel, multi megahertz X-ray camera for the European XFEL
- 2017
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. - 9781510611009
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Konferensbidrag (refereegranskat)abstract
- AGIPD is a hybrid pixel detector developed by DESY, PSI, and the Universities of Bonn and Hamburg. It is targeted for use at the European XFEL, a source with unique properties: a train of up to 2700 pulses is repeated at 10 Hz rate. The pulses inside a train are ≤100fs long and separated by 220 ns, containing up to 1012 photons of 12.4 keV each. The readout ASICs with 64 x 64 pixels each have to cope with these properties: Single photon sensitivity and a dynamic range up to 104 photons/pixel in the same image as well as storage for as many as possible images of a pulse train for delayed readout, prior to the next train. The high impinging photon flux also requires a very radiation hard design of sensor and ASIC, which uses 130 nm CMOS technology and radiation tolerant techniques. The signal path inside a pixel of the ASIC consists of a charge sensitive preamplifier with 3 individual gains, adaptively selected by a subsequent discriminator. The preamp also feeds to a correlated double sampling stage, which writes to an analogue memory to record 352 frames. It is random-access, so it can be used most efficiently by overwriting bad or empty images. Encoded gain information is stored to a similar memory. Readout of these memories is via a common charge sensitive amplifier in each pixel, and multiplexers on four differential ports. Operation of the ASIC is controlled via a command interface, using 3 LVDS lines. It also serves to configure the chip's operational parameters and timings.
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| 7. |
- Mezza, D., et al.
(författare)
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Calibration methods for charge integrating detectors
- 2022
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 1024
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Tidskriftsartikel (refereegranskat)abstract
- Since the introduction of the extremely intense X-ray free electron lasers, the need for low noise, high dynamic range and potentially fast charge integrating detectors has increased significantly. Among all the problems that research and development groups have to face in the development of such detectors, their calibration represents one of the most challenging and the collaboration between the detector development and user groups is of fundamental importance. The main challenge is to develop a calibration suite that is capable to test the detector over a wide dynamic range, with a high granularity and a very high linearity, together with a certain radiation tolerance and the possibility to well define the timings and the synchronization with the detector. Practical considerations have also to be made like the possibility to calibrate the detector in a reasonable time, the availability of the calibration source at the experimental place and so on. Such a calibration test suite is often not represented by a single source but by several sources that can cover different parts of the dynamic range and that need to be cross calibrated to have a final calibration curve. In this respect an essential part of the calibration is also to develop a mathematical model that allows calibrating the entire dynamic range, taking into account features that are calibration source and/or detector specific. The aim of this contribution is to compare the calibration for the AGIPD detector using several calibration sources such as internal current source, backside pulsing, IR pulsed laser, LED light and mono-energetic protons. The mathematical procedure used to calibrate the different sources will be discussed in great detail showing how to take into account a few shortcomings (like pixel coupling) that are common for many charge integrating detectors. This work has been carried out in the frame of the AGIPD project for the European X-ray Free Electron Laser.
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| 8. |
- Mezza, D., et al.
(författare)
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Characterization of AGIPD1.0 : The full scale chip
- 2016
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 838, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- The AGIPD (adaptive gain integrating pixel detector) detector is a high frame rate (4.5 MHz) and high dynamic range (up to 104 ·12.4 keV photons) detector with single photon resolution (down to 4 keV taking 5σ as limit and lowest noise settings) developed for the European XFEL (XFEL.EU). This work is focused on the characterization of AGIPD1.0, which is the first full scale version of the chip. The chip is 64×64 pixels and each pixel has a size of 200×200 μm2. Each pixel can store up to 352 images at a rate of 4.5 MHz (corresponding to 220 ns). A detailed characterization of the AGIPD1.0 chip has been performed in order to assess the main performance of the ASIC in terms of gain, noise, speed and dynamic range. From the measurements presented in this paper a good uniformity of the gain, a noise around 320 e− (rms) in standard mode and around 240 e− (rms) in high gain mode has been measured. Furthermore a detailed discussion about the non-linear behavior after the gain switching is presented with both experimental results and simulations.
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| 9. |
- Mezza, D., et al.
(författare)
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New calibration circuitry and concept for AGIPD
- 2016
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Ingår i: Journal of Instrumentation. - 1748-0221 .- 1748-0221. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- AGIPD (adaptive gain integrating pixel detector) is a detector system developed for the European XFEL (XFEL.EU), which is currently being constructed in Hamburg, Germany. The XFEL.EU will operate with bunch trains at a repetition rate of 10 Hz. Each train consists of 2700 bunches with a temporal separation of 220 ns corresponding to a rate of 4.5 MHz. Each photon pulse has a duration of < 100 fs (rms) and contains up to 1012 photons in an energy range between 0.25 and 25 keV . In order to cope with the large dynamic range, the first stage of each bump-bonded AGIPD ASIC is a charge sensitive preamplifier with three different gain settings that are dynamically switched during the charge integration. Dynamic gain switching allows single photon resolution in the high gain stage and can cover a dynamic range of 104 × 12.4 keV photons in the low gain stage. The burst structure of the bunch trains forces to have an intermediate in-pixel storage of the signals. The full scale chip has 352 in-pixel storage cells inside the pixel area of 200 × 200 μm2. This contribution will report on the measurements done with the new calibration circuitry of the AGIPD1.1 chip (without sensor). These results will be compared with the old version of the chip (AGIPD1.0). A new calibration method (that is not AGIPD specific) will also be shown.
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