| 1. |
- Wunderer, C. B., et al.
(författare)
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Detector developments at DESY
- 2016
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 23, s. 111-117
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Tidskriftsartikel (refereegranskat)abstract
- With the increased brilliance of state-of-the-art synchrotron radiation sources and the advent of free-electron lasers (FELs) enabling revolutionary science with EUV to X-ray photons comes an urgent need for suitable photon imaging detectors. Requirements include high frame rates, very large dynamic range, single-photon sensitivity with low probability of false positives and (multi)-megapixels. At DESY, one ongoing development project-in collaboration with RAL/STFC, Elettra Sincrotrone Trieste, Diamond, and Pohang Accelerator Laboratory-is the CMOS-based soft X-ray imager PERCIVAL. PERCIVAL is a monolithic active-pixel sensor back-thinned to access its primary energy range of 250 eV to 1 keV with target efficiencies above 90%. According to preliminary specifications, the roughly 10 cm × 10 cm, 3.5k × 3.7k monolithic sensor will operate at frame rates up to 120 Hz (commensurate with most FELs) and use multiple gains within 27 μm pixels to measure 1 to ∼ 100000 (500 eV) simultaneously arriving photons. DESY is also leading the development of the AGIPD, a high-speed detector based on hybrid pixel technology intended for use at the European XFEL. This system is being developed in collaboration with PSI, University of Hamburg, and University of Bonn. The AGIPD allows singlepulse imaging at 4.5 MHz frame rate into a 352-frame buffer, with a dynamic range allowing single-photon detection and detection of more than 10000 photons at 12.4 keV in the same image. Modules of 65k pixels each are configured to make up (multi)megapixel cameras. This review describes the AGIPD and the PERCIVAL concepts and systems, including some recent results and a summary of their current status. It also gives a short overview over other FEL-relevant developments where the Photon Science Detector Group at DESY is involved. © 2016 International Union of Crystallography.
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| 2. |
- Correa, J., et al.
(författare)
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On the Charge Collection Efficiency of the PERCIVAL Detector
- 2016
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Ingår i: Journal of Instrumentation. - : IOP. - 1748-0221 .- 1748-0221. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- The PERCIVAL soft X-ray imager is being developed by DESY, RAL, Elettra, DLS, and PAL to address the challenges at high brilliance Light Sources such as new-generation Synchrotrons and Free Electron Lasers. Typical requirements for detector systems at these sources are high frame rates, large dynamic range, single-photon counting capability with low probability of false positives, high quantum efficiency, and (multi)-mega-pixel arrangements. PERCIVAL is a monolithic active pixel sensor, based on CMOS technology. It is designed for the soft X-ray regime and, therefore, it is post-processed in order to achieve high quantum efficiency in its primary energy range (250 eV to 1 keV) . This work will report on the latest experimental results on charge collection efficiency obtained for multiple back-side-illuminated test sensors during two campaigns, at the P04 beam-line at PETRA III, and the CiPo beam-line at Elettra, spanning most of the primary energy range as well as testing the performance for photon-energies below 250 eV . In addition, XPS surface analysis was used to cross-check the obtained results.
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| 3. |
- Khromova, A., et al.
(författare)
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Report on recent results of the PERCIVAL soft X-ray imager
- 2016
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Ingår i: Journal of Instrumentation. - : IOP. - 1748-0221 .- 1748-0221. ; 11:November
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Tidskriftsartikel (refereegranskat)abstract
- The PERCIVAL (Pixelated Energy Resolving CMOS Imager, Versatile And Large) soft X-ray 2D imaging detector is based on stitched, wafer-scale sensors possessing a thick epi-layer, which together with back-thinning and back-side illumination yields elevated quantum efficiency in the photon energy range of 125–1000 eV. Main application fields of PERCIVAL are foreseen in photon science with FELs and synchrotron radiation. This requires high dynamic range up to 105 ph @ 250 eV paired with single photon sensitivity with high confidence at moderate frame rates in the range of 10–120 Hz. These figures imply the availability of dynamic gain switching on a pixel-by-pixel basis and a highly parallel, low noise analog and digital readout, which has been realized in the PERCIVAL sensor layout. Different aspects of the detector performance have been assessed using prototype sensors with different pixel and ADC types. This work will report on the recent test results performed on the newest chip prototypes with the improved pixel and ADC architecture. For the target frame rates in the 10–120 Hz range an average noise floor of 14e− has been determined, indicating the ability of detecting single photons with energies above 250 eV. Owing to the successfully implemented adaptive 3-stage multiple-gain switching, the integrated charge level exceeds 4 centerdot 106 e− or 57000 X-ray photons at 250 eV per frame at 120 Hz. For all gains the noise level remains below the Poisson limit also in high-flux conditions. Additionally, a short overview over the updates on an oncoming 2 Mpixel (P2M) detector system (expected at the end of 2016) will be reported.
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| 4. |
- Marras, A., et al.
(författare)
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Experimental characterization of the PERCIVAL soft X-ray detector
- 2016
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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 (övrigt vetenskapligt/konstnärligt)abstract
- Considerable interest has been manifested for the use of high-brilliance X-ray synchrotron sources and X-ray Free-Electron Lasers for the investigation of samples.
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| 5. |
- Correa, J., et al.
(författare)
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Characterisation of a PERCIVAL monolithic active pixel prototype using synchrotron radiation
- 2016
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Ingår i: Journal of Instrumentation. - : IOP. - 1748-0221 .- 1748-0221. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- PERCIVAL ("Pixelated Energy Resolving CMOS Imager, Versatile And Large") is a monolithic active pixel sensor (MAPS) based on CMOS technology. Is being developed by DESY, RAL/STFC, Elettra, DLS, and PAL to address the various requirements of detectors at synchrotron radiation sources and Free Electron Lasers (FELs) in the soft X-ray regime. These requirements include high frame rates and FELs base-rate compatibility, large dynamic range, single-photon counting capability with low probability of false positives, high quantum efficiency (QE), and (multi-)megapixel arrangements with good spatial resolution. Small-scale back-side-illuminated (BSI) prototype systems are undergoing detailed testing with X-rays and optical photons, in preparation of submission of a larger sensor. A first BSI processed prototype was tested in 2014 and a preliminary result—first detection of 350eV photons with some pixel types of PERCIVAL—reported at this meeting a year ago. Subsequent more detailed analysis revealed a very low QE and pointed to contamination as a possible cause. In the past year, BSI-processed chips on two more wafers were tested and their response to soft X-ray evaluated. We report here the improved charge collection efficiency (CCE) of different PERCIVAL pixel types for 400eV soft X-rays together with Airy patterns, response to a flat field, and noise performance for such a newly BSI-processed prototype sensor.
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| 6. |
- Schomburg, Eike D., et al.
(författare)
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Acute muscle inflammation enhances the monosynaptic reflexes and c-fos expression in the feline spinal cord
- 2007
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Ingår i: European Journal of Pain. - : Wiley. - 1090-3801 .- 1532-2149. ; 11:5, s. 579-586
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this research was to study the changes of the motor reflex activity (monosynaptic reflex (MSR) of the flexor and extensor muscles) and Fos immunoreactivity in lumbo-sacral spinal cord after acute induced myositis of m. gastrocnemius-soleus (GS). The experiments were carried out on ischaemic decerebrated, spinalized in C1 cats. After infiltration of the GS muscle with carrageenan (2%) MSRs of flexors and extensors showed a significant increase in amplitude +127+/-24.5% and +155+/-28.5%, respectively, p<0.05. The exposed effect was initiated within 30 min and achieved a maximum 2.8h after the intramuscular injections of carrageenan. After analysis of dynamics of the MSRs, animals were perfused and c-fos expression in the spinal segments L6-S1 was evaluated. In comparison to sham-operated animals, the number of Fos-immunoreactive (Fos-ir) cells was noticeably increased in the lumbar cord of cats with carrageenan-induced myositis. The labeled cells were concentrated in the ipsilateral laminae I/II, neck of the dorsal horn (V/VI) and intermediate zone (VII), however, clear predominance of their concentration was found in the deep laminae. The effect of muscle inflammation was also expressed as a significant decline in the number of NADPH-d-reactive cells (p<0.05) in ipsilateral laminae I/II of L6/L7. The results show that the input from acutely inflamed muscles may induce an increase of the reflex responsiveness of flexors and extensors which is not mediated via the gamma-spindle-loop and which coincides with a significant increase in c-fos expression in the deep laminae of the lumbar spinal cord.
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