Position reconstruction for segmented detectors Ebrahimi, A.; Feindt, F.; Garutti, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2021, Letnik:
1014
Journal Article
Recenzirano
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The topic of the paper is the position reconstruction from signals of segmented detectors. With the help of a simple simulation, it is shown that the position reconstruction using the ...centre-of-gravity method is strongly biased, if the width of the charge (or e.g. light) distribution at the electrodes (or photo detectors) is less than the read-out pitch. A method is proposed which removes this bias for events with signals in two or more read-out channels and thereby improves the position resolution. The method also provides an estimate of the position–response function for every event. Examples are given for which its width as a function of the reconstructed position varies by as much as an order of magnitude.
A fast Monte Carlo program is described which simulates the signals from a silicon pixel detector traversed by charged particles under different angles, and the results obtained with the proposed reconstruction method and with the centre-of-gravity method are compared. The simulation includes the local energy-loss fluctuations, the position-dependent electric field, the diffusion of the charge carriers, the electronics noise and charge thresholds for clustering, A comparison to test-beam-data is used to validate the simulation.
The LHC is planning an upgrade program which will bring the luminosity up to about 7.5×1034cm−2s−1 in 2027, with the goal of delivering an integrated luminosity of 3000 or even 4000 fb−1 by the end ...of 2037. This High Luminosity phase, HL-LHC, will present new challenges of higher data rates and unprecedented radiation levels for the pixel detector. A fluence of 2.3×1016neq/cm2, or equivalently 12 MGy, is expected for the inner layer of the CMS Inner Tracker (IT) for 3000 fb−1 of integrated luminosity. To maintain or even improve the performance of the present system, new technologies have to be exploited for the so-called Phase-2 upgrade. Among them is the future version of front-end chips in 65 nm CMOS technology by the CERN RD53 Collaboration, which supports small pixel sizes of 50 × 50 or 100×25μm2 and low pixel charge thresholds (≈1000 e−). Thin planar n-in-p type silicon sensors with a thickness of the active layer of 150 μm, segmented into pixel sizes of 100×25μm2 or 50×50μm2, will be used throughout most of the IT. They have been shown to allow for a good detector resolution that is much more stable with respect to radiation damage compared to the Phase-1 detector. CMS has launched several R&D submissions for the development of suitable planar silicon sensors at Hamamatsu Photonics K.K. and FBK Trento. We present results for measurements on such prototype sensors bump bonded to the RD53A prototype chip developed by the RD53 Collaboration at CERN. Different pixel cell designs are compared and evaluated in beam tests at CERN, DESY and FNAL for spatial resolution and hit efficiency at various track angles before and after irradiation. As an example, hit efficiencies of 99% at vertical incidence were reached after irradiation to 5×1015neq/cm2, which corresponds to the layer 2 lifetime fluence of the CMS IT.
In the last decades, the number of known tardigrade species has considerably increased to more than 960 species with new ones being discovered every year. However, the study of tardigrade species ...presents a general problem which is frequently encountered during the work with invertebrates: small size and remarkable degrees of phenotypic plasticity may sometimes not permit a definite identification of the species. In this investigation we have used riboprinting, a tool to study rDNA sequence variation, in order to distinguish tardigrade species from each other. The method combines a restriction site variation approach of ribotyping with amplified DNAs. In eight investigated species of heterotardigrades and eutardigrades we have amplified the genes for the small subunit ribosomal RNA (SSU; 18S) and subsequently sequenced the genes. Virtual riboprints were used for identification of restriction sites from ten already published 18S rDNA sequences and seven new 18S rDNA sequences. On the basis of the obtained sequences, diagnostic restriction fragment patterns can be predicted with only 11 restriction enzymes. The virtual digestion confirmed the obtained restriction fragment patterns and restriction sites of all amplified and digested tardigrade DNAs. We show that the variation in positions and number of restriction sites obtained by standard restriction fragment analysis on agarose gels can be used successfully for taxonomic identification at different taxonomic levels. The simple restriction fragment analysis provides a fast and convenient method of molecular barcoding for species identification in tardigrades.
Zusammenfassung
Im Laufe der letzten Jahrzehnte wurden viele neue Tardigradenarten beschrieben. Zur Zeit sind mehr als 960 Arten bekannt und jedes Jahr kommen neue Arten hinzu. Die Arbeit mit Tardigraden stellt jedoch oftmals ein Problem dar, das generell auch bei anderen Organismen von großer Bedeutung ist: die geringe Größe und die außergewöhnliche phenotypische Plastizität machen in vielen Fällen eine genaue Artidentifikation schwierig. In der vorliegenden Untersuchung verwenden wir das Riboprinting, eine Technik, rDNA Sequenzunterschiede zu erfassen, um damit verschiedene Tardigradenarten voneinander zu differenzieren. Diese Methode vereint den Ansatz der Restriktionsschnittstellenanalyse des Riboprinting mit amplifizierten DNAs. Von acht untersuchten Heterotardigraden und Eutardigraden wurden die Gene für die kleine ribosomale RNA Untereinheit (SSU; 18S) amplifiziert und sequenziert. Virtuelle Riboprints wurden zur Identifikation von zehn bereits publizierten 18S rDNA Sequenzen und sieben neuen 18S DNA Sequenzen erstellt. Auf der Basis der vorliegenden Sequenzen können die diagnostischen Restriktionsfragmentmuster mit insgesamt elf Restriktionsenzyme vorhergesagt werden. Der virtuelle Verdau bestätigt die Restriktionsfragmentmuster und Restriktionsschnittstellen aller amplifizierten und verdauten Tardigraden DNAs. Wir zeigen, dass die unterschiedlichen Variationen in den Positionen und Anzahl der Restriktionsschnittstellen erfolgreich zur taxonomischen Identifikation auf verschiedenen taxonomischen Ebenen verwendet werden können. Die einfache Restriktionsfragmentanalyse stellt eine schnelle und geeignete Methode für das molekulare Barcoding zur Artidentifikation bei Tardigraden dar.
In this work, charge collection profiles of non-irradiated and irradiated 150µm thick p-type pad diodes were measured using a 5.2GeV electron beam traversing the diode parallel to the readout ...electrode. Four diodes were irradiated to 1MeV neutron equivalent fluences of 2, 4, 8, and 12 × 1015cm−2 with 23MeV protons. The Charge Collection Efficiency profiles as a function of depth are extracted by unfolding the data. The results of the measurements are compared to the TCAD device simulation using three radiation damage models from literature which were tuned to different irradiation types and fluences.
Results of an extensive R&D program aiming at radiation hard, small pitch, 3D pixel sensors are reported. The CMS experiment is supporting this R&D in the scope of the Inner Tracker upgrade for the ...High Luminosity phase of the CERN Large Hadron Collider (HL-LHC). In the HL-LHC the Inner Tracker will have to withstand an integrated fluence up to 2.3×1016neq/cm2. A small number of 3D sensors were interconnected with the RD53A readout chip, which is the first prototype of 65 nm CMOS pixel readout chip designed for the HL-LHC pixel trackers. In this paper results obtained in beam tests before and after irradiation are reported. The irradiation of a single chip module was performed up to a maximum equivalent fluence of about 1×1016neq/cm2. The analysis of the collected data shows excellent performance: the spatial resolution in not irradiated sensors can reach about 3 to 5 μm, for inclined tracks, depending on the pixel pitch. The measured hit detection efficiencies are close to 99% measured both before and after the above mentioned irradiation fluence.
Pixelated silicon detectors are state-of-the-art technology to achieve precise tracking and vertexing at collider experiments, designed to accurately measure the hit position of incoming particles in ...high rate and radiation environments. The detector requirements become extremely demanding for operation at the High-Luminosity LHC, where up to 200 interactions will overlap in the same bunch crossing on top of the process of interest. Additionally, fluences up to 2.3 × 1016cm−2 1MeV neutron equivalent at 3.0cm distance from the beam are expected for an integrated luminosity of 3000fb−1. In the last decades, the pixel pitch has constantly been reduced to cope with the experiments’ needs of achieving higher position resolution and maintaining low pixel occupancy per channel. The spatial resolution improves with a decreased pixel size but it degrades with radiation damage. Therefore, prototype sensor modules for the upgrade of the experiments at the HL-LHC need to be tested after being irradiated. This paper describes position resolution measurements on planar prototype sensors with 100 × 25µm2 pixels for the CMS Phase-2 Upgrade. It reviews the dependence of the position resolution on the relative inclination angle between the incoming particle trajectory and the sensor, the charge threshold applied by the readout chip and the bias voltage. A precision setup with three parallel planes of sensors has been used to investigate the performance of sensors irradiated to fluences up to ϕeq=3.6×1015 cm−2. The measurements were performed with a 5GeV electron beam. A spatial resolution of 3.2±0.1µm is found for non-irradiated sensors, at the optimal angle for charge sharing. The resolution is 5.0±0.2µm for a proton-irradiated sensor at ϕeq=2.1×1015 cm−2 and a neutron-irradiated sensor at ϕeq=3.6×1015 cm−2. The extrapolated resolution to infinite beam momentum, where the contribution of multiple scattering can be neglected, has also been evaluated.
Complete 18S rDNA sequences and sequences of domain III of mitochondrial 12S rDNA were obtained to assess phylogenetic relationships among major suprageneric taxa of leeches and the possibly closely ...related clitellate taxa Branchiobdellida and Acanthobdellida. The monophyly of the families Erpobdellidae, Piscicolidae, and Glossiphoniidae, the suborders Erpobdelliformes and Hirudiniformes, and the order Arhynchobdellida have been confirmed by parsimony and maximum likelihood phylogenetic analysis of separate and combined data sets. Both the nuclear 18S rDNA sequences and the mitochondrial 12S rDNA sequences were consistent in not supporting a monophyletic order Rhynchobdellida, represented by the families Piscicolidae and Glossiphoniidae. A topology with the Piscicolidae as the first branch in the leech tree followed by the Glossiphoniidae received the highest support in terms of taxonomic, character, and outgroup congruence. According to this topology, the putative apomorphies of the Rhynchobdellidae (e.g. the proboscis) can be parsimoniously explained as plesiomorphies already present in the ancestral leech. This common ancestor was probably a bloodsucking leech with a proboscis rather than an unspecialized ectocommensal, as suggested by previous hypotheses. During the course of leech evolution, a reduction of the proboscis could have taken place in predatory arhynchobdellid ancestors to enable swallowing of larger prey. A second gain of sanguivory by the jawed Hirudiniformes could have been facilitated by pre‐adaptations to ectoparasitic blood feeding. The 18S rDNA analysis further indicates a close relationship between the clitellate groups Branchiobdellida and Acanthobdellida, although this relationship is not strongly supported.
R&D on novel sensor routing and test structure development Hoffmann, K.-H.; Auzinger, G.; Bergauer, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
628, Številka:
1
Journal Article
Recenzirano
The Central European Consortium designed and prototyped generic test structures (TS) in a R&D study to allow standard monitoring of the process quality of silicon sensors of any given vendor. ...Furthermore, some novel signal routing strategies for silicon sensors have been applied on the wafers to achieve an implementation of a pitch adapter directly in the sensor, either in the first metal layer or in a second additional metal routing layer. These improvements would allow to connect the readout chip directly to the sensor, omitting an additional pitch adapter. The on-sensor pitch adapter would be reflected by a substantial material budget saving which would be of special interest for the tracking detectors at the super-LHC.
After a first batch of improved TS was produced in 2007, a second batch of enhanced TS and additional sensors, with integrated pitch adapters, has been produced by the Institute of Electron Technology in Warsaw, Poland. Some improvements of the TS and the designs of the sensors will be shown. Afterwards a selection of measurements on TS and sensors will be discussed as well as a testbeam and its first results.
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