Abstract
The application of muon tomography method in small scale, for the imaging of a five-centimeter side lead cube, is being examined in the present work. The representation of the object is ...being achieved by using the transmission muography technique, in which the “free-sky” muon flux is compared to the muon flux measured within the acceptance of the detector. This comparison yields information about the absorption of the muons as they pass through the object under investigation. Also, a projective reconstruction method called “Back Projection” is tested by being applied on the data, providing information about the location of the object and its dimensions. This project has been carried out within the frame of EKATY programme, which aims to the innovative imaging of the subsurface of archaeological sites and the interior of structural elements of monuments in three and four dimensions.
Abstract
Within the frame of the EKATϒ programme, whose purpose is the innovative imaging of the subsurface of archaeological sites and the interior of structural elements of monuments in “three” and ...“four” dimensions, the applicability of Muon Tomography technique in the representation of a tumulus is tested in the present work. The scanning of its internal structure is accomplished by measuring the flux deficit of cosmic muon tracks in the presence of an object inside the tumulus, compared to the muon flux when traversing a uniform tumulus (transmission muography). The feasibility study of the method is achieved with a simulation of the tumulus geometry and the structure under investigation. Following the simulation process, a tracking telescope, consisting of four MicroMegas detectors and two trigger plastic scintillators, will be placed near Apollonia’s tumulus to collect data. For the specific latitude where the Apollonia’s tumulus is located, the energy and angular muon distribution at sea level is studied. Implementing the dimensions of the telescope in the simulation, the back-projection method is examined for the localization of the hidden object and the estimation of its dimensions. The method is tested for the telescope optimal position, placed under the tumulus, and the realistic one, placed near the tumulus at the level of its base.
A multi-core FPGA-based 2D-clustering implementation for real-time image processing is presented in this paper. The clustering algorithm is using a moving window technique to reduce the time and data ...required for the cluster identification process. The implementation is fully generic, with an adjustable detection window size. A fundamental characteristic of the implementation is that multiple clustering cores can be instantiated. Each core can work on a different identification window that processes data of independent "images" in parallel, thus, increasing performance by exploiting more FPGA resources. The algorithm and implementation are developed for the Fast TracKer processor for the trigger upgrade of the ATLAS experiment but their generic design makes them easily adjustable to other demanding image processing applications that require real-time pixel clustering.
The aim of this study is to assess the fixation of the major nutrients C, N, P, Ca, Mg, K, Na by algal biomass produced in the rice fields of Thessaloniki plain in Greece under semi-arid ...Mediterranean conditions and to evaluate the limiting factors for their growth. Measurements were performed in experimental rice-field following the regional conventional practices (C–H treatment): (a) direct sowing, (b) continuous flooding with few intermissions, (c) use of nitrogen fertilizers at 176 kg N ha
−1
, and (d) application of herbicides (active ingredients benzofenap and clomazone). Herbicides were not applied in a small part of the field isolated by bunds (C–NH treatment) in order to assess possible limiting effects of herbicides on algae growth. Climatic data, measurements of rice crop characteristics and water quality of the ponded water in the C–H part of the experimental field were also obtained in order to assess the limiting effects of light, temperature and nutrients based on a modelling approach. Green algae were found to be dominant in the specific system. Considering the two treatments, the results showed that herbicides did not affect algae growth probably due to the short period of exposure followed by the continuous flooding. Nutrients fixation by algae for C–H followed the order C (52.1 %) > Ca (5.6 %) > K (3.5 %) > N (2.4 %) > Mg (0.3 %) ≈ Na (0.3 %) > P (0.24 %) with a final dry biomass production at 1,118 kg ha
−1
. Based on the measurements and model simulations the most limiting factors under the regional conventional practices of rice cultivation were the temperature at the initial and final stage of rice growing season, the light when the leaf area index of rice was >2 and phosphorus concentration in the ponded water. The mean algae growth rate during the flooding period was estimated at 8.2 kg ha
−1
day
−1
, while the maximum rate was estimated at 15.9 kg ha
−1
day
−1
at the initial growth stages of rice before the beginning of intense light limitations from rice crop coverage.
With the luminosity upgrade of the LHC machine (SLHC, Super-LHC), the Muon system of the ATLAS experiment at CERN will also need a detector upgrade in the highest rapidity region. MAMMA, Muon ATLAS ...Micromegas Activity, is an ongoing R&D activity with the aim to develop large detectors based on the bulk-Micromegas technology for use in the ATLAS Muon Spectrometer. Micromegas is a good potential candidate for the construction of large muon chambers that combine trigger and tracking capability and can sustain high particle rates expected at the SLHC. A medium size Micromegas prototype, in scale 1:10 of the final chambers, has been built and evaluated in the laboratory and in beam tests at CERN. Results from the analysis of test-beam data are presented. The results indicate that large size Micromegas is a viable candidate for ATLAS Muon upgrade
Crimean-Congo haemorrhagic fever (CCHF) was diagnosed in a United Kingdom traveller who returned from Bulgaria in June 2014. The patient developed a moderately severe disease including fever, ...headaches and petechial rash. CCHF was diagnosed following identification of CCHF virus (CCHFV) RNA in a serum sample taken five days after symptom onset. Sequence analysis of the CCHFV genome showed that the virus clusters within the Europe 1 clade, which includes viruses from eastern Europe.
The parallel 2D pixel clustering FPGA implementation used for the input system of the ATLAS Fast TracKer (FTK) processor is presented. The input system for the FTK processor will receive data from ...the Pixel and micro-strip detectors from inner ATLAS read out drivers (RODs) at full rate, for total of 760Gbs, as sent by the RODs after level-1 triggers. The cluster detection window size can be adjusted for optimizing the cluster identification process. Additionally, the implementation can be parallelized by instantiating multiple cores to identify different clusters independently thus exploiting more FPGA resources. This flexibility makes the implementation suitable for a variety of demanding image processing applications. The implementation is robust against bit errors in the input data stream and drops all data that cannot be identified. The results of the first hardware tests of the single flow implementation on the custom FTK input mezzanine (IM) board are presented.
The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been deployed in the deep waters of the Mediterranean Sea. This digital optical module has a novel design ...with a very large photocathode area segmented by the use of 31 three inch photomultiplier tubes. It has been integrated in the ANTARES detector for in-situ testing and validation. This paper reports on the first months of data taking and rate measurements. The analysis results highlight the capabilities of the new module design in terms of background suppression and signal recognition. The directionality of the optical module enables the recognition of multiple Cherenkov photons from the same
40
K decay and the localisation of bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The 2004 H8 Testbeam setup is used as a test ground of various aspects of the ATLAS detector. The H8 study program focuses on sub-detector and trigger system performance in combined and standalone ...mode, as well as offline reconstruction and analysis, but leaves also space for specialized studies and experimental setups. In a dedicated setup, a BIS type Monitored Drift Tube chamber was placed in front of the Liquid Argon Calorimeter and was attached to its support structure. The aim of this project is to perform positioning measurements of the Liquid Argon Calorimeter electrodes using the track information from the BIS muon chamber. Moreover, the goal is to study the performance of the chamber in positron and muon beams at different beam incident angles. Last but not least, we investigate the correlation between the position of the cluster barycenter in the Liquid Argon and the reconstructed track in the BIS chamber.
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