This paper presents the detailed characterization of a single photon counting chip, named CHASE Jr., built in a CMOS 40-nm process, operating with synchrotron radiation. The chip utilizes an on-chip ...implementation of the C8P1 algorithm. The algorithm eliminates the charge sharing related uncertainties, namely, the dependence of the number of registered photons on the discriminator's threshold, set for monochromatic irradiation, and errors in the assignment of an event to a certain pixel. The article presents a short description of the algorithm as well as the architecture of the CHASE Jr., chip. The analog and digital functionalities, allowing for proper operation of the C8P1 algorithm are described, namely, an offset correction for two discriminators independently, two-stage gain correction, and different operation modes of the digital blocks. The results of tests of the C8P1 operation are presented for the chip bump bonded to a silicon sensor and exposed to the 3.5-μm-wide pencil beam of 8-keV photons of synchrotron radiation. It was studied how sensitive the algorithm performance is to the chip settings, as well as the uniformity of parameters of the analog front-end blocks. Presented results prove that the C8P1 algorithm enables counting all photons hitting the detector in between readout channels and retrieving the actual photon energy.
New physics experiments at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt require application-optimized detector readout circuits. The STS/MUCH-XYTER2 (or SMX2) is a new, ...128-channel prototype ASIC for silicon strip detectors and gas electron multiplier (GEM) detectors in the Compressed Baryonic Matter (CBM) experiment. It provides self-triggered amplitude and time measurement of incoming charge and serial streaming of digitized data. The 10 mm × 6.75 mm chip was fabricated employing the UMC CMOS 180 nm process. It comprises of an analog front-end with dual-path processing including a timing comparator in one path and a continuous-time 5-bit analog-to-digital converter in the other path, a digital back-end with time pre-sorting, advanced monitoring and throttling features and multiple 320 Mbps, serial links targeted for a GBT-based data acquisition structure. Specific conditions of the detector systems will be discussed prior to the structure and the features of the ASIC together with measurement results.
We report on the design of an active feedback circuit for charge sensitive amplifiers used for reading out hybrid pixel detectors. The predominant advantages of the proposed feedback over the ...existing solutions are its low noise, stability, and tunability. In addition, the circuit occupies small silicon area, which is crucial for hybrid pixel detectors. This paper presents both the mathematical analysis of the proposed circuit and measurement results obtained with the test structure.
The advent of high-speed x-ray photon correlation spectroscopy now allows the study of critical phenomena in fluids to much smaller length scales and over a wider range of temperatures than is ...possible with dynamic light scattering. We present an x-ray photon correlation spectroscopy study of critical fluctuation dynamics in a complex fluid typical of those used in liquid-liquid extraction (LLE) of ions, dodecane-DMDBTDMA with extracted aqueous Ce (NO3)3. We observe good agreement with both static and dynamic scaling without the need for significant noncritical background corrections. Critical exponents agree with 3D Ising values, and the fluctuation dynamics are described by simple exponential relaxation. The form of the dynamic master curve deviates somewhat from the Kawasaki result, with a more abrupt transition between the critical and noncritical asymptotic behavior. The concepts of critical phenomena thus provide a quantitative framework for understanding the structure and dynamics of LLE systems and a path forward to new LLE processes.
We report on a novel technique of an in-pixel multilevel offset correction to be used in hybrid pixel detector readout circuits operating in a single photon counting mode. This technique was ...implemented in a prototype integrated circuit consisting of 23,552 square shaped pixels of 75 μm pitch, which was designed and manufactured in CMOS 130 nm technology. Each pixel contains a charge sensitive amplifier, shaper, two discriminators, two 14-bit counters and a block for multilevel offset correction. The effective gain and offset are controlled individually in each pixel. The measurement results prove very good uniformity of the prototype integrated circuit with an offset spread of only 7e - rms and a gain spread of 2.5%.
Liquid–liquid extraction (LLE), the go-to process for a variety of chemical separations, is limited by spontaneous organic phase splitting upon sufficient solute loading, called third phase ...formation. In this study we explore the applicability of critical phenomena theory to gain insight into this deleterious phase behavior with the goal of improving separations efficiency and minimizing waste. A series of samples representative of rare earth purification were constructed to include each of one light and one heavy lanthanide (cerium and lutetium) paired with one of two common malonamide extractants (DMDOHEMA and DMDBTDMA). The resulting postextraction organic phases are chemically complex and often form rich hierarchical structures whose statics and dynamics near the critical point were probed herein with small-angle X-ray scattering and high-speed X-ray photon correlation spectroscopy. Despite their different extraction behaviors, all samples show remarkably similar critical behavior with exponents well described by classical critical point theory consistent with the 3D Ising model, where the critical behavior is characterized by fluctuations with a single diverging length scale. This unexpected result indicates a significant reduction in relevant chemical parameters at the critical point, indicating that the underlying behavior of phase transitions in LLE rely on far fewer variables than are generally assumed. The obtained scalar order parameter is attributed to the extractant fraction of the extractant/diluent mixture, revealing that other solution components and their respective concentrations simply shift the critical temperature but do not affect the nature of the critical fluctuations. These findings point to an opportunity to drastically simplify studies of liquid–liquid phase separation and phase diagram development in general while providing insights into LLE process improvement.
Climate is one of the main causes of forest fires in Europe. In addition, forest fires are influenced by other factors, such as the reconstruction of tree stands with a uniform species composition ...and increasing human pressure. At the same time, the increasing number of fires is accompanied by a steady increase in the number and quality of spatial information collected, which affects the ability to conduct more accurate studies of forest fires. The appropriate use of spatial information systems (GIS) together with all the collected information on fires could provide new insights into their causes and, in further steps, allow the development of new, more accurate predictive models. The objectives of the study were: (i) to estimate the probability of fire occurrence in the period 2007-2016; (ii) to evaluate the performance of the developed model; (iii) to identify and quantify anthropogenic, topographic and stand factors affecting the probability of fire occurrence in forest areas in Poland. To achieve these objectives, a statistical model based on a logistic regression approach was built using the nationwide forest fire database for the period from 2007 to 2016. The information in the database was obtained from the Polish State Forest Information System (SILP). Then it was supplemented with spatial, topographic and socio-economic information from various spatial and statistical databases. The results showed that fire probability is significantly positively affected by population density and distance from buildings. In addition, the further the distance from roads and railways, watercourses and water objects or the edge of the forest, height above sea level, and steep slopes, the lower is the fire probability. Analysis of spatial, ecological and socio-economic factors provides new insights that contribute to a better understanding of fire occurrence in Poland.
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