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Start Over Author "Paraschou, K." Topic fos: physical sciences
4 results on '"Paraschou, K."'

1. Precise timing and recent advancements with segmented anode PICOSEC Micromegas prototypes

Author

Manthos, I., Aune, S., Bortfeldt, J., Brunbauer, F., David, C., Desforge, D., Fanourakis, G., Gallinaro, M., García, F., Giomataris, I., Gustavsson, T., Iguaz, F. J., Kallitsopoulou, A., Kebbiri, M., Kordas, K., Lampoudis, C., Legou, P., Lisowska, M., Liu, J., Lupberger, M., Maillard, O., Maniatis, I., Müller, H., Oliveri, E., Papaevangelou, T., Paraschou, K., Pomorski, M., Qi, B., Resnati, F., Ropelewski, L., Sampsonidis, D., Scharenberg, L., Schneider, T., Sohl, L., van Stenis, M., Tsiamis, A., Tsipolitis, Y., Tzamarias, S. E., Utrobicic, A., Veenhof, R., Wang, X., White, S., Zhang, Z., Zhou, Y., Aristotle University of Thessaloniki, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CERN [Genève], Institute of Nuclear and Particle Physics (NCSR DEMOKRITOS), Universidade de Lisboa, Helsinki Institute of Physics (HIP), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Center for Interdisciplinary Research and Innovation (CIRI), University of Science and Technology of China [Hefei] (USTC), Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Capteurs et Instrumentation pour la Mesure (LCIM-LIST), Département d'instrumentation Numérique (DIN (CEA-LIST)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and National Technical University of Athens [Athens] (NTUA)

Subjects
Physics - Instrumentation and Detectors, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Detectors and Experimental Techniques, Instrumentation, physics.ins-det, Mathematical Physics
Abstract

Timing information in current and future accelerator facilities is important for resolving objects (particle tracks, showers, etc.) in extreme large particles multiplicities on the detection systems. The PICOSEC Micromegas detector has demonstrated the ability to time 150\,GeV muons with a sub-25\,ps precision. Driven by detailed simulation studies and a phenomenological model which describes stochastically the dynamics of the signal formation, new PICOSEC designs were developed that significantly improve the timing performance of the detector. PICOSEC prototypes with reduced drift gap size ($\sim$\SI{119}{\micro\metre}) achieved a resolution of 45\,ps in timing single photons in laser beam tests (in comparison to 76\,ps of the standard PICOSEC detector). Towards large area detectors, multi-pad PICOSEC prototypes with segmented anodes has been developed and studied. Extensive tests in particle beams revealed that the multi-pad PICOSEC technology provides also very precise timing, even when the induced signal is shared among several neighbouring pads. Furthermore, new signal processing algorithms have been developed, which can be applied during data acquisition and provide real time, precise timing., 5 pages, 3 figures, 12th International Conference on Position Sensitive Detectors

Published
2022
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2. Study of the PICOSEC-Micromegas Detector with Test Beam Data and Phenomenological Modelling of its Response

Author

Paraschou, K.

Subjects
Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, FOS: Physical sciences, High Energy Physics::Experiment, Instrumentation and Detectors (physics.ins-det)
Abstract

In this work, a part of the Research and Development effort of the PICOSEC detector is presented. The PICOSEC detector is a novel gas-filled detector, based on the Micromegas detector, which has been developed by the RD-51 PICOSEC collaboration. Instead of relying on traditional direct ionization, the PICOSEC detector takes advantage of the prompt timing characteristics of Cherenkov radiation by converting the Cherenkov photons into electrons through the use of a photocathode. The detector has been put into two type of tests where experimental data are collected. One involves a laser beam and a single photoelectron response at CEA-SACLAY, while the other involves a test beam of 150 GeV muons at the CERN SPS H4 secondary beamline, with multiple photoelectrons. The methods employed in the statistical analysis of the detector's timing properties are summarized and in their application an optimal time resolution of 76 ps is achieved for single photoelectrons. A strange dependence of the mean timing on the size of the electron peak is observed, which mimics the behaviour of the "time walk" effect. A simulation of the detector is developed to study the timing properties, which is also the main scope of the thesis. After a detailed investigation, it is found that the electrons in the gaseous mixture move with a different drift velocity before and after the first multiplication, introducing this "time walk" effect, and a phenomenological explanation of this effect is provided. Finally, a maximum likelihood statistical method for the estimation of the mean number of photoelectron extracted per particle is developed and an optimal time resolution of 24 ps is achieved with a mean number of photoelectrons per particle equal to 10.4. In this work, a deep understanding is acquired on a new detector which has brought upon unprecedented results in the field of gas-filled detectors., Master's thesis, School of Physics, Aristotle University of Thessaloniki, Greece, March 2018. 124 pages, 62 figures, 11 tables

Published
2020

3. New CAST Limit on the Axion-Photon Interaction

Author

CAST collaboration, Anastassopoulos, V., Aune, S., Barth, K., Belov, A., Brauninger, H., Cantatore, G., Carmona, J. M., Castel, J. F., Cetin, S. A., Christensen, F., Collar, J. I., Dafni, T., Davenport, M., Decker, T. A., Dermenev, A., Desch, K., Eleftheriadis, C., Fanourakis, G., Ferrer-Ribas, E., Fischer, H., Garcia, J. A., Gardikiotis, A., Garza, J. G., Gazis, E. N., Geralis, T., Giomataris, I., Gninenko, S., Hailey, C. J., Hasinoff, M. D., Hoffmann, D. H. H., Iguaz, F. J., Irastorza, I. G., Jakobsen, A., Jacoby, J., Jakovcic, K., Kaminski, J., Karuza, M., Kralj, N., Krcmar, M., Kostoglou, S., Krieger, Ch., Lakic, B., Laurent, J. M., Liolios, A., Ljubicic, A., Luzon, G., Maroudas, M., Miceli, L., Neff, S., Ortega, I., Papaevangelou, T., Paraschou, K., Pivovaroff, M. J., Raffelt, G., Rosu, M., Ruz, J., Choliz, E. Ruiz, Savvidis, I., Schmidt, S., Semertzidis, Y. K., Solanki, S. K., Stewart, L., Vafeiadis, T., Vogel, J. K., Yildiz, S. C., Zioutas, K., Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CAST, Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Anastassopoulos, V., Aune, S., Barth, K., Belov, A., Bräuninger, H., Cantatore, Giovanni, Carmona, J. M., Castel, J. F., Cetin, S. A., Christensen, F., Collar, J. I., Dafni, T., Davenport, M., Decker, T. A., Dermenev, A., Desch, K., Eleftheriadis, C., Fanourakis, G., Ferrer Ribas, E., Fischer, H., García, J. A., Gardikiotis, A., Garza, J. G., Gazis, E. N., Geralis, T., Giomataris, I., Gninenko, S., Hailey, C. J., Hasinoff, M. D., Hoffmann, D. H. H., Iguaz, F. J., Irastorza, I. G., Jakobsen, A., Jacoby, J., Jakovčić, K., Kaminski, J., Karuza, M., Kralj, N., Krčmar, M., Kostoglou, S., Krieger, C. h., Lakić, B., Laurent, J. . m., Liolios, A., Ljubičić, A., Luzón, G., Maroudas, M., Miceli, L., Neff, S., Ortega, I., Papaevangelou, T., Paraschou, K., Pivovaroff, M. J., Raffelt, G., Rosu, M., Ruz, J., Chóliz, E. Ruiz, Savvidis, I., Schmidt, S., Semertzidis, Y. . k., Solanki, S. K., Stewart, L., Vafeiadis, T., Vogel, J. K., Yildiz, S. C., and Zioutas, K.

Subjects
solar axion, Photon, Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, General Physics and Astronomy, magnetic field, 01 natural sciences, 7. Clean energy, law.invention, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Axion, law, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Detectors and Experimental Techniques, physics.ins-det, [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Physics, Large Hadron Collider, Instrumentation and Detectors (physics.ins-det), Axions, solar axions, axion helioscope, dark matter, axion-like particles, CERN LHC Coll, S029IAG, CAST, axion: mass, Astrophysics::Earth and Planetary Astrophysics, CERN Axion Solar Telescope, Particle Physics - Experiment, Particle physics, CERN Lab, Dark matter, FOS: Physical sciences, Telescope, Nuclear physics, [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, Coupling constant, Helioscope, hep-ex, 010308 nuclear & particles physics, background, coupling constant, axions, dark matter, axion helisocope, axion-photon coupling, sensitivity, magnet, coupling: (axion 2photon), High Energy Physics::Experiment, axion: solar, experimental results
Abstract

During 2003--2015, the CERN Axion Solar Telescope (CAST) has searched for $a\to\gamma$ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. In its final phase of solar axion searches (2013--2015), CAST has returned to evacuated magnet pipes, which is optimal for small axion masses. The absence of a significant signal above background provides a world leading limit of $g_{a\gamma} < 0.66 \times 10^{-10} {\rm GeV}^{-1}$ (95% C.L.) on the axion-photon coupling strength for $m_a \lesssim 0.02$ eV. Compared with the first vacuum phase (2003--2004), the sensitivity was vastly increased with low-background x-ray detectors and a new x-ray telescope. These innovations also serve as pathfinders for a possible next-generation axion helioscope., Comment: Second version after referees comments (post-print). Published version available Open Access at https://www.nature.com/articles/nphys4109

Published
2017
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4. Improved search for solar chameleons with a GridPix detector at CAST

Author

Wolfgang Funk, Milica Krčmar, T. Geralis, M. Maroudas, S. C. Yildiz, I. G. Irastorza, Joachim Jacoby, Sofia Kostoglou, Babette Döbrich, Sergei Gninenko, Giovanni Cantatore, C. Krieger, Søren Schmidt, M. Davenport, Marin Karuza, I. Ortega, M. J. Pivovaroff, Konstantin Zioutas, C. J. Hailey, J. Ruz, S. Neff, L. Miceli, T. Papaevangelou, S. Aune, Georg G. Raffelt, T. Dafni, I. Savvidis, M. Vretenar, Klaus Kurt Desch, Biljana Lakić, A. Liolios, Georgios Fanourakis, Nenad Kralj, Alexander Dermenev, J. F. Castel, A. Belov, Krešimir Jakovčić, L. Stewart, Dieter Hoffmann, Sami K. Solanki, Heinrich Bräuninger, Serkant Ali Cetin, E. Ruiz Chóliz, F.J. Iguaz, Vassilis Anastassopoulos, H. Fischer, A. Gardikiotis, Yannis K. Semertzidis, M. D. Hasinoff, C. Eleftheriadis, Jochen Kaminski, Anders Clemen Jakobsen, K. Paraschou, E. Ferrer-Ribas, J. M. Carmona, Julia Vogel, Theodoros Vafeiadis, J. G. Garza, K. Barth, G. Luzón, Walter Wuensch, I. Giomataris, M. Rosu, P. Brax, Ante Ljubičić, J. M. Laurent, J. A. Garcia, Evangelos Gazis, Finn Erland Christensen, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), CAST, Anastassopoulos, V., Aune, S., Barth, K., Belov, A., Bräuninger, H., Cantatore, G., Carmona, J. M., Castel, J. F., Cetin, S. A., Christensen, F., Dafni, T., Davenport, M., Dermenev, A., Desch, K., Döbrich, B., Eleftheriadis, C., Fanourakis, G., Ferrer-Ribas, E., Fischer, H., Funk, W., García, J. A., Gardikiotis, A., Garza, J. G., Gazis, E. N., Geralis, T., Giomataris, I., Gninenko, S., Hailey, C. J., Hasinoff, M. D., Hoffmann, D. H. H., Iguaz, F. J., Irastorza, I. G., Jakobsen, A., Jacoby, J., Jakovčić, K., Kaminski, J., Karuza, M., Kostoglou, S., Kralj, N., Krčmar, M., Krieger, C., Lakić, B., Laurent, J. M., Liolios, A., Ljubičić, A., Luzón, G., Maroudas, M., Miceli, L., Neff, S., Ortega, I., Papaevangelou, T., Paraschou, K., Pivovaroff, M. J., Raffelt, G., Rosu, M., Ruz, J., Chóliz, E. Ruiz, Savvidis, I., Schmidt, S., Semertzidis, Y. K., Solanki, S. K., Stewart, L., Vafeiadis, T., Vogel, J. K., Vretenar, M., Wuensch, W., Yildiz, S. C., Zioutas, K., and Brax, P.

Subjects
Physics - Instrumentation and Detectors, Photon, Physics::Instrumentation and Detectors, Solar luminosity, magnetic field, Astrophysics, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), photon: coupling, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Astrophysics::Solar and Stellar Astrophysics, Detectors and Experimental Techniques, GridPix, dark energy, modified gravity, physics.ins-det, Solar physics, Physics, dark energy experiments, particle physics - cosmology connection, solar physics, Astronomy and Astrophysics, chameleon: solar, solar physic, Instrumentation and Detectors (physics.ins-det), Coupling (probability), transition: (axion photon), dark energy experiment, Beta (plasma physics), Physics::Space Physics, CAST, Astrophysics::Earth and Planetary Astrophysics, CERN Axion Solar Telescope, Particle Physics - Experiment, chameleon, Modified gravity, Particle physics, CERN Lab, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, photon: spectrum, coupling constant: upper limit, Tachocline, Astrophysics::Cosmology and Extragalactic Astrophysics, X-ray, Dark energy experiments, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Sensitivity (control systems), hep-ex, background, 010308 nuclear & particles physics, magnet, coupling: (axion 2photon), Particle physics - cosmology connection, axion: solar, tachocline, Energy (signal processing), experimental results
Abstract

We report on a new search for solar chameleons with the CERN Axion Solar Telescope (CAST). A GridPix detector was used to search for soft X-ray photons in the energy range from 200 eV to 10 keV from converted solar chameleons. No signiffcant excess over the expected background has been observed in the data taken in 2014 and 2015. We set an improved limit on the chameleon photon coupling, $\beta_\gamma < 5.7\times10^{10}$ for $1, Comment: 19 pages, 12 figures, 3 tables

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