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The PERCIVAL detector is a CMOS imager designed for the soft X-ray regime at photon sources. Although still in its final development phase, it has recently seen its first user experiments: ptychography at a free-electron laser, holographic imaging at a storage ring and preliminary tests on X-ray photon correlation spectroscopy. The detector performed remarkably well in terms of spatial resolution achievable in the sample plane, owing to its small pixel size, large active area and very large dynamic range; but also in terms of its frame rate, which is significantly faster than traditional CCDs. In particular, it is the combination of these features which makes PERCIVAL an attractive option for soft X-ray science.

Journal of synchrotron radiation 28(1), 131 - 145 (2021). doi:10.1107/S1600577520013958, In this paper the back-side-illuminated Percival 2-Megapixel (P2M) detector is presented, along with its characterization by means of optical and X-ray photons. For the first time, the response of the system to soft X-rays (250 eV to 1 keV) is presented. The main performance parameters of the first detector are measured, assessing the capabilities in terms of noise, dynamic range and single-photon discrimination capability. Present limitations and coming improvements are discussed., Published by Wiley-Blackwell, [S.l.]

A new multielement X-ray fluorescence detector is presented, specifically designed to probe the chemical speciation of trace 3d elements down to the p.p.m. range., X-ray absorption fine-structure (XAFS) spectroscopy can assess the chemical speciation of the elements providing their coordination and oxidation state, information generally hidden to other techniques. In the case of trace elements, achieving a good quality XAFS signal poses several challenges, as it requires high photon flux, counting statistics and detector linearity. Here, a new multi-element X-ray fluorescence detector is presented, specifically designed to probe the chemical speciation of trace 3d elements down to the p.p.m. range. The potentialities of the detector are presented through a case study: the speciation of ultra-diluted elements (Fe, Mn and Cr) in geological rocks from a calcareous formation related to the dispersal processes from Ontong (Java) volcanism (mid-Cretaceous). Trace-elements speciation is crucial in evaluating the impact of geogenic and anthropogenic harmful metals on the environment, and to evaluate the risks to human health and ecosystems. These results show that the new detector is suitable for collecting spectra of 3d elements in trace amounts in a calcareous matrix. The data quality is high enough that quantitative data analysis could be performed to determine their chemical speciation.

The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump–probe experiments. Among others, the low-α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low-α mode of the experimental set-ups developed at the TEMPO beamline to perform pump–probe experiments with soft X-rays based on photoelectron or photon detection are presented. A 282 kHz repetition-rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two-dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time-resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high-time-resolution pump–probe experiments compared and discussed. Fil: Silly, Mathieu G.. Synchrotron Soleil; Francia Fil: Ferte, Tom. Synchrotron Soleil; Francia Fil: Tordeux, Marie Agnes. Synchrotron Soleil; Francia Fil: Pierucci, Debora. Synchrotron Soleil; Francia Fil: Beaulieu, Nathan. Synchrotron Soleil; Francia Fil: Chauvet, Christian. Synchrotron Soleil; Francia Fil: Pressacco, Federico. Synchrotron Soleil; Francia Fil: Sirotti, Fausto. Synchrotron Soleil; Francia Fil: Popescu, Horia. Synchrotron Soleil; Francia Fil: Lopez Flores, Victor. Synchrotron Soleil; Francia Fil: Tortarolo, Marina del Carmen. Synchrotron Soleil; Francia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sacchi, Maurizio. Universite de Paris Vi. Institut des Nanosciences de Paris; Francia Fil: Jaouen, Nicolas. Synchrotron Soleil; Francia Fil: Hollander, Philippe. Synchrotron Soleil; Francia Fil: Ricaud, Jean Paul. Synchrotron Soleil; Francia Fil: Bergeard, Nicolas. Synchrotron Soleil; Francia Fil: Boeglin, Christine. Synchrotron Soleil; Francia Fil: Tudu, Bharati. Synchrotron Soleil; Francia Fil: Delaunay, Renaud. Universite de Paris VI; Francia Fil: Luning, Jan. Universite de Paris VI; Francia Fil: Malinowski, Gregory. Synchrotron Soleil; Francia Fil: Hehn, Michel. Synchrotron Soleil; Francia Fil: Baumier, Cedric. Université Paris Sud; Francia Fil: Fortuna, Franck. Université Paris Sud; Francia Fil: Krizmancic, Damjan. Elettra - Synchrotron Light Laboratory; Italia Fil: Stebel, Luigi. Elettra - Synchrotron Light Laboratory; Italia Fil: Sergo, Rudi. Elettra - Synchrotron Light Laboratory; Italia Fil: Cautero, Giuseppe. Elettra - Synchrotron Light Laboratory; Italia

The photoionization dynamics of OsO4 and RuO4, chosen as model systems of small-size mononuclear heavy-metal complexes, has been theoretically studied by the time-dependent density functional theory (TDDFT). Accurate experimental measurements of photoionization dynamics as a benchmarking test for the theory are reported for the photoelectron asymmetry parameters of outer valence ionizations of OsO4, measured in the 17-90 eV photon energy range. The theoretical results are in good agreement with the available experimental data. The observed dynamical behavior of partial cross sections and asymmetry parameters has been related to both the coupling to the continuum of discrete excited states, giving strong modulations in the photon energy dependency, and the atomic composition of the initial ionized states, which determines the rate of decay of ionization probability for increasing excitation energies. Overall, an extensive analysis of the photoionization dynamics for valence and core orbitals is presented, showing good agreement with all the available experimental data. This provides confidence for the validity of the TDDFT approach in describing photoionization of heavy transition element compounds, with the perspective of being used for larger systems. Further experimental work is suggested for RuO4 to gather evidence of the sensitivity of the theoretical method to the nature of the metal atom.

X-ray computed micro-tomography (μCT) is one of the most advanced and common non-destructive techniques in the field of medical imaging and material science. It allows recreating virtual models (3D models), without destroying the original objects, by measuring three-dimensional X-ray attenuation coefficient maps of samples on the (sub) micrometer scale. The quality of the images obtained using μCT is strongly dependent on the performance of the associated X-ray detector i.e. to the acquisition of information of the X-ray beam traversing the patient/sample being precise and accurate. Detectors for μCT have to meet the requirements of the specific tomography procedure in which they are going to be used. In general, the key parameters are high spatial resolution, high dynamic range, uniformity of response, high contrast sensitivity, fast acquisition readout and support of high frame rates. At present the detection devices in commercial μCT scanners are dominated by charge-coupled devices (CCD), photodiode arrays, CMOS acquisition circuits and more recently by hybrid pixel detectors. Monolithic CMOS imaging sensors, which offer reduced pixel sizes and low electronic noise, are certainly excellent candidates for μCT and may be used for the development of novel high-resolution imaging applications. The uses of monolithic CMOS based detectors such as the PERCIVAL detector are being recently explored for synchrotron and FEL applications. PERCIVAL was developed to operate in synchrotron and FEL facilities in the soft X-ray regime from 250 eV to 1 keV and it could offer all the aforementioned technical requirements needed in μCT experiments. In order to adapt the system for a typical tomography application, a scintillator is required, to convert incoming X-ray radiation (∼ tens of KeV) into visible light which may be detected with high efficiency. Such a taper-based scintillator was developed and mounted in front of the sensitive area of the PERCIVAL imager. In this presentation we will report the setup of the detector system and preliminary results of first μCTs of reference objects, which were performed in the TomoLab at ELETTRA.

The valence and core-level photoelectron spectra of gaseous indole, 2,3-dihydro-7-azaindole, and 3-formylindole have been investigated using VUV and soft X-ray radiation supported by both an ab initio electron propagator and density functional theory calculations. Three methods were used to calculate the outer valence band photoemission spectra: outer valence Green function, partial third order, and renormalized partial third order. While all gave an acceptable description of the valence spectra, the last method yielded very accurate agreement, especially for indole and 3-formylindole. The carbon, nitrogen, and oxygen is core-level spectra of these heterocycles were measured and assigned. The double ionization appearance potential for indole has been determined to be 21.8 +/- 0.2 eV by C is and N is Auger photoelectron spectroscopy. Theoretical analysis identifies the doubly ionized states as a band consisting of two overlapping singlet states and one triplet state with dominant configurations corresponding to holes in the two uppermost molecular orbitals. One of the singlet states and the triplet state can be described as consisting largely of a single configuration, but other doubly ionized states are heavily mixed by configuration interactions. This work provides full assignment of the relative binding energies of the core level features and an analysis of the electronic structure of substituted indoles in comparison with the parent indole.

Time resolved experiments are among the most powerful tools in physic for exploring photoelectron spectroscopy phenomena over time scales from milliseconds to picoseconds Moreover, acquisition systems with versatility and real-time computing are needed. Cross Delay-Lines detectors (CDL) are extremely suitable for these applications, since arrival time measurement is exploited to perform position detection, allowing to provide both information together. Typical architectures for acquisition systems are based on Aplication Specific Integrated Circuit (ASIC) Time-to-Digital Converters (TDCs) followed by a Field Programmable Logic Array (FPGA); fast parallel computing is combined with time precision, allowing to perform state-of-the-art time resolved experiments. Nevertheless, the limiting factor of this architecture is the absence of reconfigurability of the ASIC that strongly limits the customization respect to the requests of a specific set-up. Especially today, where the state-of-the-art TDCs implemented in FPGA, is comparable to the ASIC solutions. In 2019 Nuclear Science Symposium, we presented a fully-reconfigurable FPGA-based solution, where the TDC and the image reconstruction algorithm were hosted in two FPGAs. In particular, we focused on the 4-channel TDC that, guarantees high-performance in terms of resolution (1 ps), Full-Scale Range (200 µs), Integral Non Linearity, (4 ps over 500 ns), In this contribution, we give significant improvements in order to satisfy the aforementioned experimental experimental requests. In fact, the “pulse-to-pulse” dead-time of the TDC has been reduced from 20 ns to 7 ns, and the transmission rate between the FPGAs has been incremented from 10 to 100 Msps. Furthermore, we have increased the number of channels of the TDC from 4 to 8. This makes possible to correlate the CDL events with signals coming from other sources that can be as well Time-of-Fight or laser pulses as other CDL signals.

In this paper, we are presenting the results of the first test of the Percival P2M-FSI detector with tender x-rays photons at a synchrotron beamline. Percival is a monolithic CMOS Imager for detection of x-rays in Synchrotron Rings and Free Electron Lasers: the Front-Side-Illuminated (FSI) version of the detector has been proven able to successfully distinguish tender (2keV) x-ray single photons.

High brilliance synchrotrons and FELs require high performing detector systems to realise their full potential. High dynamic range, low noise and high frame rate are all of great importance. In this paper we present first optical characterization results of the P2M CMOS sensor, designed for soft X-ray detection at such facilities. Previous work is summarised and an overview of the sensor is presented. Test results for the sensor’s column-parallel ADC and readout chain are presented, and first test results for the pixel acquired using the Photon Transfer Curve (PTC) method are shown. Finally, an outline of future work is provided.

In many experiments involving detection of events, information is represented both by position and time of occurrence of the interaction. For the latter, the resolution is a primary demand that must remain compliant with global versatility and fast real-time computing of the system.At the basis of this kind of measurements are detectors providing at the same time X-Y position and the arrival time t of each detected event. Among these detectors, Cross Delay-Lines (CDL) detectors are one of the reference solutions and use the information of detection time also for determining the position of the event.The requests of precise time measurement and fast computing time-resolved experiments are nowadays fulfilled at best by the combination of Time-to-Digital Converter (TDC) architectures with spatial computing environment of Field Programmable Gate Array (FPGA) devices. Although very promising results have been achieved, time resolution necessary to imaging applications is still a serious limiting factor.Starting from a previous system introduced in [5], in which a multi-channel TDC is combined with efficient readout logic to maximize the overall efficiency, we propose a re-design of this system both in the hardware and firmware parts. In particular, the TDC reduces the Integral Non-Linearity error (INL) from 80 ps over 50 ns of full scale-range to 4 ps over 0.5 ms, maintaining resolution up to 1 ps and single-shot precision of the channel lower than 12 ps r.m.s.This has greatly improved the overall performance of the detected image of the CDL detector, allowing a spatial X/Y precision up to 35/50 mm r.m.s. respectively without local aberrations due to the INL.

2019 26th IEEE International Conference on Electronics, Circuits and Systems (ICECS), Genoa, Italy, 27 Nov 2019 - 29 Nov 2019; ... IEEE International Symposium on Circuits and Systems proceedings 51, 50 (2019). doi:10.1109/ICECS46596.2019.8964996, High brilliance synchrotrons and Free Electron Lasers (FELs) require high performing detector systems to realise their full potential. High dynamic range, low noise and high frame rate are all of great importance. In this paper we describe the P2M CMOS sensor, designed for soft X-ray detection at such facilities. We refer to previous work on test devices demonstrating a noise of 5Me- and quantum efficiency of >80% at 400eV (and with good sensitivity even below this value). Initial test results on the first Front Side Illuminated (FSI) 2 Megapixel device are also presented, and an outline of future work is described., Published by Inst. of Electr. and Electronics Engineers, New York, N.Y.

In this paper, we are presenting the Percival detector, a monolithic CMOS Imager for detection of soft x-rays in Synchrotron Rings and Free Electron Lasers. The imager consists in a 2D array of many (2M) small (27um pitch) pixels, without dead or blind zones in the imaging area. The imager achieves low noise and high dynamic range by means of an adaptive-gain in-pixel circuitry, that has been validated on prototypes. The imager features on-chip Analogue-to-Digital conversion to 12+1 bits, and has a readout speed which is compatible with most of Free Electron Laser Facilities. For direct detection of low-energy x-rays, the imager is back-illuminated and post-processed to achieve 100% fill factor.

This work reports on the recent activities carried out by the Detector and Instrumentation Laboratory of Elettra Sincrotrone Trieste. Since both the Elettra synchrotron and the Fermi free electron laser are generating photons in the low to medium x-ray energy range from some eV to tenths of keV the activities of the detector and instrumentation laboratory focuses on spectroscopic and imaging photon detectors, which feature high quantum efficiency from below the carbon edge and are operated also in UHV environments. Special focus will be drawn on custom made monolithic and multi element silicon drift detectors for the Twinmic and the XRF beam line at Elettra. Regarding low energy imaging detectors the PERCIVAL CMOS (‘Pixelated Energy Resolving CMOS Imager, Versatile and Large’) will be discussed which is currently being developed by a collaboration of DESY, RAL, Elettra, PAL and DLS to address the need for this type of detectors for free electron lasers in the soft X-ray regime. The majorities of Elettra’s soft x-ray beam lines are employing fast and spatially resolving electron detectors and their associated readout electronics, which have been developed in-house and have been tailored to the specific needs of the respective beam line. In addition devices for in situ beam diagnostics and dose monitoring for synchrotron radiation and FEL beams have been developed and are operated on a daily basis. Moreover, some recent results in basic research on room temperature semiconductors will be discussed. It is noteworthy that Elettra Sincrotrone Trieste through its Industrial Liaison Office commercializes many of these devices and the associated read-out electronics. In this presentation an overview of these devices and their application to specific scientific applications will be given and in view of upgrade programs future directions will be discussed.

The PERCIVAL collaboration to develop a soft X-ray imager able to address the challenges of high brilliance light sources, such as new-generation synchrotrons and Free Electron Lasers, has reached one of its major milestones: a full 2-MegaPixel (P2M) system (uninterrupted 4 × 4 cm2 active area) has already seen its first light.Smaller prototypes of the device, a monolithic active pixel sensor based on CMOS technology, have already been fully characterised, and have demonstrated high frame rate, large dynamic range, and relatively high quantum efficiency.The PERCIVAL modular layout allows for clover-leaf like arrangement of up to four P2M systems. Moreover, it will be post-processed in order to achieve a high quantum efficiency in its primary energy range (250 eV to 1 keV).We will present the P2M system, its status and newest results, bring these in context with achieved prototype performance, and outline future steps.

Time-resolved experiments often need detection devices able to provide information about position and arrival time of each detected event. Cross Delay-Lines detectors (CDL), which use arrival time information also for position detection, are the most suited instruments for this task and time resolution is a fundamental requirement, along with the high versatility and fast real-time computing. Typical acquisition architectures, based on Time-to-Digital Converters (TDC) followed by a Field Programmable Gate Array (FPGA), combine very fast parallel computing with a high time precision, allowing to perform state-of-the-art time-resolved experiments. In these devices, time precision as much as time accuracy are fundamental in order to guarantee a homogenous time-to-space conversion. Nevertheless, time resolution is still a limiting factor when time resolved experiments are associated to imaging.In 2017 at Nuclear Science Symposium, inside ″Development of fully FPGA-based 3D (X, Y, t) detection systems using multichannel Tapped Delay-Line Time-to-Digital Converter with Cross Delay-Line detectors″ we presented a new approach, combining FPGA-based multi-channel TDC and an efficient multipurpose readout logic addressed to CDL detector. In this contribution, thanks to the modularity and reconfigurability offered by the FPGA, we redesigned the firmware that describes the TDC increasing the resolution from 10 ps to 1 ps, the channel precision from 15 ps r.m.s. to 9.7 ps r.m.s. and, reducing the accuracy from 200 ps to 40 ps.As result, we have greatly improved the overall performance and versatility of CDL detector systems allowing image acquisition with spatial precision better than 30 μm.These make possible the application in a multidisciplinary research center like the Elettra and FERMI lightsources where electron analyzers and Time-of-Flight devices endowed with CDL detectors allow very high spatial and time resolved spectroscopy experiments.

We present a new bidimensional detector setup, based on cross delay line technology, specifically developed for time resolved experiments and particularly suited to work in conjunction with pump-and-probe systems. Thanks to the particular architecture of the acquisition electronics, the detector is able to correlate each event with the time it occurred in a way which preserves the picoseconds time resolution of pump-and-probe techniques and, more generally, can perform time resolved acquisition in the nanosecond or picoseconds scale. The acquisition setup count rate, up to more than 4 Mcounts/s in time resolved mode, exceeds the performances of the best two-dimensional detectors working in counting mode presently available on electron analysers. First experimental results, obtained both on bench tests and in UHV conditions, where the detector has been mounted on an electron analyser, confirm the validity of the approach and show the potentiality of time resolved acquisition applied to electron spectroscopy analysis.

Time-resolved experiments often need detection devices able to provide information about position and arrival time of each detected event. Time resolution is a fundamental requirement for these devices, along with the high versatility and fast real-time computing of the acquisition system. Typical architectures, based on Time-to-Digital Converters (TDC) followed by a FPGA, combine very fast parallel computing with a time precision better than hundreds of picoseconds, allowing to perform state-of-the-art time-resolved experiments. Nevertheless, time resolution is still a limiting factor, in particular for imaging applications where the detector spatial resolution is determined through time measurement. Furthermore, the separation between the TDC devices and a readout FPGA has some drawbacks in terms of versatility of the system. In this article, we present a new approach, combining FPGA-based multi-channel Tapped-Delay-Line TDC and an efficient multipurpose readout logic, to greatly improve the overall performance and versatility of Cross Delay-Line (CDL) detector systems.

This paper presents an optimization model to reduce the gap between planning and scheduling activities in pipeline networks for supply of petroleum derivatives, so as to effectively operate the plans developed at higher decision levels. Most of the information taken in the petroleum supply chain is unidirectional, from the strategic level passing through the tactical level and finally reaching the operational level. However, unviable schedules are often obtained from an operational standpoint, since operational criteria are not considered when decisions are made at the strategic and tactical levels. In particular, in the supply chain of refined petroleum products, the production campaigns of the refineries are defined for different regions based on the consumer market and no operational conditions related to distribution are accounted at this stage. This fact that may lead to operational infeasibilities. To overcome this type of problem the present paper proposes a Mixed Integer Linear Programming (MILP) ...

The peak brilliance reached by today's Free-Electron Laser and Synchrotron light sources requires photon detectors matching their output intensity and other characteristics in order to fully realiz ...

Over the last decade, synchrotron radiation sources have seen a significant increase in brilliance, and the advent of free electron lasers has made entire new research fields accessible to investigations with X-rays. These advances in light source capabilities have resulted not only in a host of scientific advances and discoveries, but also in a need for a new generation of X-ray imaging detectors that can match the sources' capabilities in terms of frame rate and image dynamic range while recording image information with fine granularity over a large - preferably uninterrupted - (multi)megapixel area with single-photon sensitivity. Developing such next-generation imagers is both costly and time-consuming, and the requirements at many photon science facilities are similar enough to invite a collaborative effort. The Percival ("Pixellated Energy Resolving CMOS Imager, Versatile And Large") imager is being developed by a collaboration of DESY, Rutherford Appleton Laboratory (RAL), Elettra, and Diamond Light Source (DLS) to answer this need for the soft X-ray regime

iWoRiD 2015, Hamburg, Germany, 28 Jun 2015 - 2 Jul 2015; Journal of Instrumentation 11(02), C02090 (2016). doi:10.1088/1748-0221/11/02/C02090, 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., Published by Inst. of Physics, London

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 10^6 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.

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.

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 single-pulse 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.

A velocity map imaging/ion time-of-flight spectrometer designed specifically for pump-probe experiments combining synchrotron and laser radiations is described. The in-house built delay line detector can be used in two modes: the high spatial resolution mode and the coincidence mode. In the high spatial resolution mode a kinetic energy resolution of 6% has been achieved. The coincidence mode can be used to improve signal-to-noise ratio for the pump-probe experiments either by using a gate to count electrons only when the laser is present or by recording coincidences with the ion formed in the ionization process.

Here, we report on a novel experimental apparatus for performing time-resolved soft x-ray absorption spectroscopy in the sub-ns time scale using non-hybrid multi-bunch mode synchrotron radiation. The present setup is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the ~500 MHz x-ray synchrotron radiation bunches and on a detection system that discriminates and singles out the significant x-ray photon pulses by means of a custom made photon counting unit. The whole setup has been validated by measuring the time evolution of the L(3) absorption edge during the melting and the solidification of a Ge single crystal irradiated by an intense ultrafast laser pulse. These results pave the way for performing synchrotron time-resolved experiments in the sub-ns time domain with variable repetition rate exploiting the full flux of the synchrotron radiation.

Advances in laser and Synchrotron Radiation instrumentation are continuously boosting fundamental research on the electronic structure of matter. At Elettra the collaboration between several groups active in the field of atomic, molecular and cluster physics and the Instrumentation and Detector Laboratory has resulted in an experimental set-up that successfully tackles the challenges posed by the investigation of the electronic structure of isolated species in the gas phase. The use of Synchrotron Radiation (SR) and Free Electron Laser (FEL) light, allows to cover a wide spectrum of targets from energetic to dynamics. We developed a Velocity Map Imaging (VMI) spectrometer that allows to perform as well SR as FEL experiments, just by changing part of the detection system. In SR experiments, at the Gasphase beamline of Elettra, a cross delay line detector is used, coupled to a 4-channel time-to-digital converter that reconstructs the position of the electrons. Simultaneously, a Time-of-Flight (TOF) mass spectrometer is used to acquire photoion spectra. Such a system allows PhotoElectron-PhotoIon-Coincidence (PEPICO) spectroscopy of atoms, molecules and clusters. In FEL experiments (notably differing from SR experiments in the much higher rate of events produced and detected, which forces one to forfeit coincidence detection), at the Low Density Matter (LDM) beamline of FERMI, a Micro Channel Plate (MCP) a phosphor screen and a CCD camera are used instead, capable of shot-by-shot collection of practically all events, albeit without time resolution.

The PERCIVAL ("Pixelated Energy Resolving CMOS Imager, Versatile and Large") is a collaboration of DESY, RAL/STFC, ELETTRA, and DLS to develop a monolithic active pixel sensor (MAPS) to provide a suitable detector for photon science for the photon energy regime between 250 eV and 1 keV. An important performance parameter is the spatial resolution which can be inferred from the Modulation Transfer Function (MTF). The MTF measures in optical systems the relative contrast of a pattern in function of the spatial frequency. With a back-thinned and back-illuminated PERCIVAL prototype chip, dedicated MTF evaluation data were taken at Elettra's TwinMic Beamline in March 2014 at a photon energy of 535 eV. We will present our MTF derivation approaches together with MTF results for 3 pixel types of the irradiated test sensor.

Free-Electron Lasers and Synchrotrons are rapidly increasing in brilliance. This has led a requirement of large dynamic range and high frame rate sensors that is now being fulfilled by the PERCVIAL CMOS imager for direct X-ray detection developed at Rutherford Appleton Laboratory. Utilising a lateral overflow pixel and back-side illumination, PERCIVAL simultaneously achieves low-noise single-photon detection and high full well up to 107 e−, all while maintaining a frame rate of 120Hz. PERCIVAL is currently in test structure stage, and will be produced in 2 Mpixel and 13 Mpixel “waferscale” variants in 2015.

The PERCIVAL soft-X-ray (250 eV 1 keV) image detector project is a collaboration between DESY, STFC, Elettra Sincrotrone Trieste and Diamond Light Source. The objective of the project is to develop a back-thinned CMOS detector which outperforms present soft-X ray image detector technology, in terms of sensor size, noise, dynamic range and frame rate. The size of this 13M pixel imager associated with its 120 frames per second frame rate impose very challenging requirements to the Data Acquisition Backend of the system. A DAQ backend system architecture, using a commercial deep-buffer switch to rearrange image data streams coming from different regions of the sensor via several 10Gbps Ethernet links has been proposed to reassemble image frames. Real-time data processing is to be performed on multiple, parallel commodity compute nodes. This contribution to the conference reports on benchmarking tests performed as a feasibility study, and presents the resulting recommendations for the system architecture of the PERCIVAL detector DAQ backend. The feasibility study covered three key issues: Reliably moving data in UDP packets from multiple 10Gbps Ethernet links from the DAQ front-end electronics to commodity compute nodes; Real-time processing on the compute nodes; and finally streaming data to a central parallel storage system.

A novel prototype detector for scintimammography is presented. The detector is built according to a modular strategy. Each module is composed of an array of p–i–n diodes, coupled to a CsI(Tl) scintillator and to mixed-mode ASICs with self-triggering, sparsifying, A/D conversion and bidirectional serial data I/O transfer capabilities. The front-end electronics exhibits good performance in terms of equivalent input noise charge (ENC − rms). Digital signals are routed out so that each module can be attached to a main board with an FPGA for overall detector management. PC-based supervision of the detector is accomplished using a LabVIEW graphical user interface.

With the increased brilliance of state-of-the-art Synchrotron radiation sources and the advent of Free Electron Lasers 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 counting capability with low probability of false positives, and (multi)-megapixels. PERCIVAL (``Pixelated Energy Resolving CMOS Imager, Versatile and Large'') is currently being developed by a collaboration of DESY, RAL, Elettra and DLS to address this need for the soft X-ray regime. PERCIVAL is a monolithic active pixel sensor (MAPS), i.e. based on CMOS technology. It will be back-thinned to access its primary energy range of 250 eV to 1 keV with target efficiencies above 90%. According to its preliminary specifications, the roughly 10 × 10 cm2, 3520 × 3710 pixel monolithic sensor will operate at frame rates up to 120 Hz (commensurate with most FELs) and use multiple gains within its 27 μm pixels to measure (e.g. at 500 eV) 1 to ~ 105 simultaneously-arriving photons. Currently, small-scale front-illuminated prototype systems (160 × 210 pixels) are undergoing detailed testing with visible-light as well as X-ray photons.

Our goal is to provide the scientific community with a large (10cm × 10cm) pixellated detector featuring a large dynamic range (1–105 photons), good spatial resolution (27µm), good Quantum Efficiency (QE) in the low energy range (250eV–1keV), variable readout speed (up to 120 frames/s), i.e. with characteristics compatible with user needs at today's of low-energy Free Electron Lasers (FEL) and synchrotron sources.

This paper presents a novel approach to aid the operational decision-making of scheduling activities in a real-world pipeline used to transport heavy oil derivatives. Heavy oil derivatives are products of less aggregate value, such as fuel oils, e.g. Marine Fuel. These products present some special characteristics for their transport. Indeed due to their viscosity at the room temperature it is impossible to transport them without heating. Thus, when transporting such products through pipelines the entire pipeline network (and the storage tanks) must be maintained heated during the entire pumping process. Such characteristics imply that a specific model oriented to this type of problem must be developed. Some papers have already addressed scheduling decisions within pipeline networks, but the considered scenario is particularly complex. In a heavy oil derivatives pipeline system, it's common to use the same tank for different products during the scheduling horizon, thus changing the aggregate capacity of storage for some products. This procedure is known as the exchange of service of the tank. In order to perform the programmed movements, it's frequent the relocation of a tank from one product to another, decreasing the storage capacity of the former while increasing the later. In addition, a lot of constraints are modelled, as instance, product blending in line, tankage constraints, volume of pipes, production/consumption constraints, and a series of operational requirements. The approach proposed in this work is formed by a decomposition procedure that uses a sequence of mathematic models and heuristicsto solve the problem. The proposed approach is tested using a real-world scenario, composed of a pipeline tree system. The model has been extensively tested in typical operational scenarios. Such models have been solved to optimality in few CPU seconds using a commercial package.

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.

Photoelectron distributions of the polarized $2{p}^{5}3d$ Rydberg states of neon have been studied with a newly built velocity map imaging analyzer. The atoms were polarized by absorption of synchrotron radiation and ionized by an infrared laser. The asymmetry parameters ${\ensuremath{\beta}}_{2}$ and ${\ensuremath{\beta}}_{4}$ characterizing two-photon resonant ionization have been extracted from the measured images and compared with the results of a quantum defect treatment. To achieve a good theoretical description of the data, it is necessary to take into account the dependence of the dipole transition matrix elements and phases of the partial waves on the angular momentum quantum numbers pertaining to various continuum channels.

This paper presents a new approach for sequencing of batches in a complex pipeline network by using Constraint Programming (CP) techniques. These batches are composed by oil derivatives to be transferred by the pipeline network. Although many papers found in the literature usually deal with reduced pipeline topologies, the network considered in this work is quite complex. It involves nine areas, including three refineries, one harbor and five distribution centers interconnected by fifteen multiproduct pipelines. Although this paper only focus on sequencing of batches, the final task is to provide a complete transfer scheduling for the pipeline network. This scheduling is accomplished by means of three key elements: assignment, sequencing and timing. The proposed CP model considered for sequencing of batches introduces particular features of the problem that can be used by specialized solvers. This approach aims to consider time delays introduced by the pipeline network during product transfers. Preliminary results show that a suitable ordering of batches can be obtained for improving inventory levels. Besides, results show a better performance when compared to a heuristic approach which can fail for some particular cases.

This paper addresses the problem of developing an optimisation structure to aid the operational decision-making of scheduling activities in a real-world pipeline network. During the scheduling horizon, many batches are pumped from (or passing through) different nodes (refineries, harbours or distribution terminals). Pipelines are shared resources operated and monitored 365 days a year, 24 hours per day. Scheduling details must be given, including pumping sequence in each node, volume of batches, tankage constraints, timing issues, while respecting a series of operational constraints. The balance between demand requirements and production campaigns, while satisfying inventory management issues and pipeline pumping procedures, is a difficult task. Based on key elements of scheduling, a decomposition approach is proposed using an implementation suitable for model increase. Operational insights have been derived from the obtained solutions, which are given in a reduced computational time for oil industrial-size scenarios.

This paper addresses the problem of developing an optimisation structure to aid the operational decision-making of scheduling activities in a real-world pipeline network. During the scheduling horizon, many batches are pumped from (or passing through) different areas. Pipes are a disputed resource. Scheduling details must be given, including pumping sequence in each area, batches' volume, tankage constraints, timing issues, while respecting a series of operational constraints. In addition, the electric energy presents on-peak demand hours, typically, from 5:30 p.m. to 8:30 p.m., and this feature also influences operational decisions. The balance between demand requirements and production campaigns, while satisfying inventory management issues and pipeline pumping procedures, is a difficult task. The proposed approach has been successfully applied to industrial-size scenarios. Many insights have been derived from the obtained solutions.

This work develops an optimization model to aid the operational decision-making in a real work tank farm scheduling. The short term scheduling of tank farm is a hard task because the specialist has to take into account issues concerning plant topology, mass balances, transfer policies, resource constraints, demand pattern, and changeovers. So this operational decision-making is still based on experience with the aid of manual computations. The main goal of this work is to reduce the difference between a theretical model and the practical needs. In order to reduce this difference the formulation addresses a new aspect related to the operator procedure. When the operator executes the programmed activities many tasks are delayed or advanced for personal convenience. This fact can cause bottlenecks in the system operation. In order to avoid them, some considerations about qualitative variables are inserted in the model. So that the generated scheduling tends to be more practical to represent the qualitative variables by means of fuzzy system. Moreover the scheduling problem is modeled in a unified framework, which uses Constraint Logic Programming (CLP) and Mixed Integer Linear Programming (MILP). This approach had a computational time smaller than only the MILP model, and is able to define a good solution in few seconds. The proposed model can be used to test and correct new operational conditions and scenarios rather than to just determine the scheduling of regular activities.

In this paper, we report the development of a prototype for a new kind of detector intended for scintimammography imaging. Traditional photon counting information is available; moreover, digital words representing the amplitude of each event and suitable image elaboration methods significantly enhance the detector capabilities. The prototype detector is composed of a collimator and four imaging modules. Each module is composed of an 8x8 sensing array of 2x2mm silicon PIN photodiode pixels, coupled to a CsI(Tl) scintillator and custom readout electronics. The sensor is fixed to an Al"2O"3 printed circuit board. Eight readout mixed analog-digital integrated circuits, wire bonded to the sensor pixels, provide analog signal conditioning, A/D conversion, self-triggered acquisition and bidirectional serial data transfer. Digital signals are routed out so that each module can be attached to a main board with suitable control logic for overall detector management. PC-based supervision of the detector is accomplished through an USB 2.0 interconnection using an easy-to-use graphical user interface. The purpose of the prototype is to test the approach and the chosen architecture; all its elements have been designed in order to permit the construction of the final detector with a significantly larger sensing area.

In this paper we report the development of a prototype for a new kind of detector intended for scintimammography imaging. Traditional photon counting information is available; moreover digital words representing the amplitude of each event and suitable image elaboration methods significantly enhance detector capabilities. The prototype detector is composed of a collimator and 4 imaging modules. Each module is composed of an 8times8 sensing array of 2 mmtimes2 mm silicon p-i-n photodiode pixels, coupled to a CsI(Tl) scintillator and custom readout electronics. The sensor is fixed to an Al2O3 printed circuit board. Eight readout mixed analog-digital ICs, wire bonded to single sensor pixels and to the PCB, provide analog signal conditioning, A/D conversion, self-triggered acquisition and bidirectional serial data transfer. Digital signals are routed out so that each module can be attached to a main board with an FPGA for overall detector management. PC-based supervision of the detector is accomplished using a LabVIEW simplified graphical user interface. The purpose of the prototype is to test the approach and the chosen architecture; all its elements have been designed in order to permit the construction of the final detector with a significantly larger sensing area

This paper presents two models for the Liquefied Petroleum Gas (LPG) transfer and storage operations in a refinery. First, a simulation model is proposed, based on Petri Nets, which integrates the continuous and discrete parts of the process. The second model uses mixed integer linear programming techniques for the optimisation and scheduling of the system. The models allow the visualization and simulation of the problem, helping the system operator to easily test and correct scheduling plans despite the complexity of the operations. Results from the simulation model, when applied on the optimisation model, can then be used to reduce the severity of the problem.