| 1. |
- Becker, J., et al.
(författare)
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The detector simulation toolkit HORUS
- 2012
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 7:10, s. Art. no. C10009-
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, X-ray detectors used and developed at synchrotron sources and Free Electron Lasers (FELs) have become increasing powerful and versatile. However, as the capabilities of modern X-ray cameras grew so did their complexity and therefore their response functions are far from trivial. Since understanding the detecting system and its behavior is vital for any physical experiment, the need for dedicated powerful simulation tools arose. The HPAD Output Response fUnction Simulator (HORUS) was originally developed to analyze the performance implications of certain design choices for the Adaptive Gain Integrating Pixel Detector (AGIPD) and over the years grew to a more universal detector simulation toolkit covering the relevant physics in the energy range from below 1 keV to a few hundred keV. HORUS has already been used to study possible improvements of the AGIPD for X-ray Photon Correlation Spectroscopy (XPCS) at the European XFEL and its performance at low beam energies. It is currently being used to study the optimum detector layout for Coherent Diffration Imaging (CDI) at the European XFEL. Simulations of the charge summing mode of the Medipix3 chip have been essential for the improvements of the charge summing mode in the Medipix3 RX chip. HORUS is universal enough to support arbitrary hybrid pixel detector systems (within limitations). To date, the following detector systems are predefined within HORUS: The AGIPD, the Large Pixel Detector (LPD), the Cornell-Stanford Pixel Array Detector (CSPAD), the Mixed-Mode (MMPAD) and KEKPAD, and the Medipix2, Medipix3 and Medipix3 RX chips. © 2012 IOP Publishing Ltd and Sissa Medialab srl.
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| 2. |
- Graafsma, Heinz, et al.
(författare)
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Detector developments for photon science at DESY
- 2023
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Ingår i: Frontiers in Physics. - : Frontiers Media SA. - 2296-424X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
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| 4. |
- Marras, A., et al.
(författare)
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Development of CoRDIA : An Imaging Detector for next-generation Synchrotron Rings and Free Electron Lasers
- 2022
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Ingår i: Journal of Physics. - : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- An x-ray imager is being developed for use in diffraction-limited synchrotron rings and continuous wave free electron lasers. The imager is named CoRDIA (COntinuous Readout Digitising Imager Array) and aims at achieving continuous operation at a frame rate in excess of 100kHz. Other goals include single-photon sensitivity at 12 keV (or below), a full well in excess of 10k photon/pixel/image, and a 100μm pixel pitch. The detector ASIC will be compatible with multiple sensor materials to cover different energy ranges. Exploratory prototypes of the readout ASIC (basic circuital blocks) have been manufactured in TSMC 65nm technology: they are presently under test.
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| 5. |
- Marras, A., et al.
(författare)
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Development of the Continuous Readout Digitising Imager Array detector
- 2024
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Ingår i: Journal of Instrumentation. - : IOP Publishing. - 1748-0221. ; 19:3
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Tidskriftsartikel (refereegranskat)abstract
- The CoRDIA project aims to develop an X-ray imager capable of continuous operation in excess of 100 kframe/s. The goal is to provide a suitable instrument for Photon Science experiments at diffraction-limited Synchrotron Rings and Free Electron Lasers considering Continuous Wave operation. Several chip prototypes were designed in a 65 nm process: in this paper we will present an overview of the challenges and solutions adopted in the ASIC design.
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| 6. |
- Nawaz, S., et al.
(författare)
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Explainable machine learning for diffraction patterns
- 2023
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Ingår i: Journal of applied crystallography. - : International Union of Crystallography (IUCr). - 0021-8898 .- 1600-5767. ; 56:5, s. 1494-1504
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Tidskriftsartikel (refereegranskat)abstract
- Serial crystallography experiments at X-ray free-electron laser facilities produce massive amounts of data but only a fraction of these data are useful for downstream analysis. Thus, it is essential to differentiate between acceptable and unacceptable data, generally known as 'hit' and 'miss', respectively. Image classification methods from artificial intelligence, or more specifically convolutional neural networks (CNNs), classify the data into hit and miss categories in order to achieve data reduction. The quantitative performance established in previous work indicates that CNNs successfully classify serial crystallography data into desired categories [Ke, Brewster, Yu, Ushizima, Yang & Sauter (2018). J. Synchrotron Rad. 25, 655-670], but no qualitative evidence on the internal workings of these networks has been provided. For example, there are no visualization methods that highlight the features contributing to a specific prediction while classifying data in serial crystallography experiments. Therefore, existing deep learning methods, including CNNs classifying serial crystallography data, are like a 'black box'. To this end, presented here is a qualitative study to unpack the internal workings of CNNs with the aim of visualizing information in the fundamental blocks of a standard network with serial crystallography data. The region(s) or part(s) of an image that mostly contribute to a hit or miss prediction are visualized.
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| 7. |
- Rahmani, V., et al.
(författare)
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Data reduction for X-ray serial crystallography using machine learning
- 2023
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Ingår i: Journal of applied crystallography. - 0021-8898 .- 1600-5767. ; 56, s. 200-213
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Tidskriftsartikel (refereegranskat)abstract
- Serial crystallography experiments produce massive amounts of experimental data. Yet in spite of these large-scale data sets, only a small percentage of the data are useful for downstream analysis. Thus, it is essential to differentiate reliably between acceptable data (hits) and unacceptable data (misses). To this end, a novel pipeline is proposed to categorize the data, which extracts features from the images, summarizes these features with the 'bag of visual words' method and then classifies the images using machine learning. In addition, a novel study of various feature extractors and machine learning classifiers is presented, with the aim of finding the best feature extractor and machine learning classifier for serial crystallography data. The study reveals that the oriented FAST and rotated BRIEF (ORB) feature extractor with a multilayer perceptron classifier gives the best results. Finally, the ORB feature extractor with multilayer perceptron is evaluated on various data sets including both synthetic and experimental data, demonstrating superior performance compared with other feature extractors and classifiers.
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| 8. |
- Roberts, A., et al.
(författare)
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First demonstration of 3D optical readout of a TPC using a single photon sensitive Timepix3 based camera
- 2019
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Ingår i: Journal of Instrumentation. - : Institute of Physics Publishing. - 1748-0221. ; 14:6
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Tidskriftsartikel (refereegranskat)abstract
- The ARIADNE project is developing innovative optical readout technologies for two-phase liquid Argon time projection chambers (LArTPCs). Optical readout presents an exciting alternative to the current paradigm of charge readout. Optical readout is simple, scalable and cost effective. This paper presents first demonstration of 3D optical readout of TPC, using CF4 gas as a proof of principle. Both cosmic rays and an Americium-241 alpha source have been imaged in 100 mbar CF4. A single-photon sensitive camera was developed by combining a Timepix3 (TPX3) based camera with an image intensifier. When a pixel of TPX3 is hit, a packet containing all information about the hit is produced. This packet contains the x,y coordinates of the pixel, time of arrival (ToA) and time over threshold (ToT) information. The z position of the hit in the TPC is determined by combining drift velocity with ToA information. 3D event reconstruction is performed by combining the pixel's x,y location with this calculated z position. Calorimetry is performed using time over threshold, a measure of the intensity of the hit. © 2019 IOP Publishing Ltd and Sissa Medialab.
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| 9. |
- Sarajlić, M., et al.
(författare)
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Germanium "hexa" detector : Production and testing
- 2017
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Here we present new result on the testing of a Germanium sensor for X-ray radiation. The system is made of 3 × 2 Medipix3RX chips, bump-bonded to a monolithic sensor, and is called "hexa". Its dimensions are 45 × 30 mm2 and the sensor thickness was 1.5 mm. The total number of the pixels is 393216 in the matrix 768 × 512 with pixel pitch 55 μ m. Medipix3RX read-out chip provides photon counting read-out with single photon sensitivity. The sensor is cooled to -126°C and noise levels together with flat field response are measured. For -200 V polarization bias, leakage current was 4.4 mA (3.2 μ A/mm2). Due to higher leakage around 2.5% of all pixels stay non-responsive. More than 99% of all pixels are bump bonded correctly. In this paper we present the experimental set-up, threshold equalization procedure, image acquisition and the technique for bump bond quality estimate.
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| 10. |
- Sarajlic, M., et al.
(författare)
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Progress on TSV technology for Medipix3RX chip
- 2017
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The progress of Through Silicon Via (TSV) technology for Medipix3RX chip done at DESY is presented here. The goal of this development is to replace the wire bonds in X-ray detectors with TSVs, in order to reduce the dead area between detectors. We obtained the first working chips assembled together with Si based sensors for X-ray detection. The 3D integration technology, including TSV, Re-distribution layer deposition, bump bonding to the Si sensor and bump bonding to the carrier PCB, was done by Fraunhofer Institute IZM in Berlin. After assembly, the module was successfully tested by recording background radiation and making X-ray images of small objects. The active area of the Medipix3RX chip is 14.1 mm x 14.1 mm or 256 x 256 pixels. During TSV processing, the Medipix3RX chip was thinned from 775 mu m original thickness, to 130 mu m. The diameter of the vias is 40 mu m, and the pitch between the vias is 120 mu m. A liner filling approach was used to contact the TSV with the RDL on the backside of the Medipix3RX readout chip.
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