T. Papaevangelou
A5047902474- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Radiation Detection and Scintillator Technologies
- Particle physics theoretical and experimental studies
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- Neutrino Physics Research
- Photocathodes and Microchannel Plates
- CCD and CMOS Imaging Sensors
- Nuclear reactor physics and engineering
- Nuclear physics research studies
- Astronomy and Astrophysical Research
- Particle Accelerators and Free-Electron Lasers
- Radiation Therapy and Dosimetry
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Muon and positron interactions and applications
- Magnetic confinement fusion research
- Adaptive optics and wavefront sensing
CEA Paris-Saclay
2016-2025
Institut de Recherche sur les Lois Fondamentales de l'Univers
2016-2025
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016-2025
Istituto Nazionale di Fisica Nucleare, Sezione di Padova
2024
Université Paris-Saclay
2017-2024
CEA Paris-Saclay - Etablissement de Saclay
2011-2023
European Organization for Nuclear Research
2004-2022
Aristotle University of Thessaloniki
2002-2022
Universitat de Barcelona
2022
Universidad de Zaragoza
2015-2022
Hypothetical low-mass particles, such as axions, provide a compelling explanation for the dark matter in universe. Such particles are expected to emerge abundantly from hot interior of stars. To test this prediction, CERN Axion Solar Telescope (CAST) uses 9 T refurbished Large Hadron Collider magnet directed towards Sun. In strong magnetic field, solar axions can be converted X-ray photons which recorded by detectors. 2013–2015 run, thanks low-background detectors and new telescope,...
We have searched for solar axions or similar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup with improved conditions in all detectors. From absence of excess X-rays when magnet was pointing Sun, we set an upper limit on axion-photon coupling 8.8 x 10^{-11} GeV^{-1} at 95% CL m_a <~ 0.02 eV. This result is best experimental over a broad range axion masses and eV also supersedes previous derived from energy-loss arguments globular-cluster stars.
The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO look for axions or axion-like particles (ALPs) originating in the Sun via Primakoff conversion of solar plasma photons. In terms signal-to-noise ratio, about 4–5 orders magnitude more sensitive than CAST, currently most powerful helioscope, reaching sensitivity to axion-photon couplings down few × 10−12 GeV−1 and thus probing large fraction unexplored ALP parameter space....
Hypothetical axionlike particles with a two-photon interaction would be produced in the sun by Primakoff process. In laboratory magnetic field ("axion helioscope"), they transformed into x-rays energies of few keV. Using decommissioned Large Hadron Collider test magnet, CERN Axion Solar Telescope ran for about 6 months during 2003. The first results from analysis these data are presented here. No signal above background was observed, implying an upper limit to axion-photon coupling...
We have searched for solar axions or other pseudoscalar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup. Whereas we previously reported results from CAST with evacuated magnet bores (Phase I), setting limits on lower mass axions, here report where were filled 4He gas II) of variable pressure. The introduction generates a refractive photon mγ, thereby achieving maximum possible conversion rate those axion masses ma match mγ. With 160 different...
The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using 3He as a buffer gas. At T=1.8 K this allows larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with 4He. With about 1 h of data taking at each 252 different we have scanned the mass range 0.39 eV < m_a 0.64 eV. From absence excess X-rays when magnet was pointing Sun set typical upper limit on axion-photon coupling g_ag 2.3 x 10^{-10} GeV^{-1} 95% CL, exact...
We study the feasibility of a new generation axion helioscope, most ambitious and promising detector solar axions to date. show that large improvements in magnetic field volume, x-ray focusing optics backgrounds are possible beyond those achieved CERN Axion Solar Telescope (CAST). For hadronic models, sensitivity axion-photon coupling gaγ ≳ few × 10−12 GeV−1 is conceivable, 1–1.5 orders magnitude CAST sensitivity. If also couple electrons, Sun produces larger flux for same value Peccei-Quinn...
A new Micromegas manufacturing technique, based on kapton etching technology, has been developed recently, resulting in further improvement of the characteristics detector, such as uniformity and stability. Excellent energy resolution obtained, reaching 11% FWHM for 5.9 keV photon peak the55Fe X-ray source 1.8% (with possible evidence less than 1%) 5.5 MeV alpha 241Am source. The Microbulk detector shows several advantages like flexible structure, low material high radio-purity, opening thus...
The CERN Axion Solar Telescope has finished its search for solar axions with (3)He buffer gas, covering the range 0.64 eV ≲ ma 1.17 eV. This closes gap to cosmological hot dark matter limit and actually overlaps it. From absence of excess x rays when magnet was pointing Sun we set a typical upper on axion-photon coupling gaγ 3.3 × 10(-10) GeV(-1) at 95% C.L., exact value depending pressure setting. Future direct axion searches will focus increasing sensitivity smaller values gaγ, example by...
We review the physics potential of a next generation search for solar axions: International Axion Observatory (IAXO) . Endowed with sensitivity to discover axion-like particles (ALPs) coupling photons as small gaγ∼ 10−12 GeV−1, or electrons gae∼10−13, IAXO has find QCD axion in 1 meV∼1 eV mass range where it solves strong CP problem, can account cold dark matter Universe and be responsible anomalous cooling observed number stellar systems. At same time, will have enough detect lower axions...
A bstract This article describes BabyIAXO, an intermediate experimental stage of the International Axion Observatory (IAXO), proposed to be sited at DESY. IAXO is a large-scale axion helioscope that will look for axions and axion-like particles (ALPs), produced in Sun, with unprecedented sensitivity. BabyIAXO conceived test all subsystems (magnet, optics detectors) relevant scale final system thus serve as prototype IAXO, but same time fully-fledged physics reach itself, potential discovery....
In non-hadronic axion models, which have a tree-level axion-electron interaction, the Sun produces strong flux by bremsstrahlung, Compton scattering, and axio-recombination, ``BCA processes.'' Based on new calculation of this flux, including for first time we derive limits Yukawa coupling gae axion-photon interaction strength gaγ using CAST phase-I data (vacuum phase). For ma≲10 meV/c2 find < 8.1 × 10−23 GeV−1 at 95% CL. We stress that next-generation helioscope such as proposed IAXO could...
Standard Model extensions often predict low‐mass and very weakly interacting particles, such as the axion. A number of small‐scale experiments at intensity/precision frontier are actively searching for these elusive complementing searches physics beyond colliders. Whilst a next generation will give access to huge unexplored parameter space, discovery would have tremendous impact on our understanding fundamental physics.
The CERN Axion Solar Telescope (CAST) searches for $a\ensuremath{\rightarrow}\ensuremath{\gamma}$ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward Sun. Two parallel bores filled with helium adjustable pressure to match x-ray refractive mass ${m}_{\ensuremath{\gamma}}$ axion search ${m}_{a}$. After vacuum phase (2003--2004), which is optimal ${m}_{a}\ensuremath{\lesssim}0.02\text{ }\text{ }\mathrm{eV}$, we used $^{4}\mathrm{He}$ 2005--2007...
Abstract The PICOSEC Micromegas (MM) detector is a precise timing gaseous based on MM operating in two-stage amplification mode and Cherenkov radiator. Prototypes equipped with cesium iodide (CsI) photocathodes have shown promising time resolutions as 24 picoseconds (ps) for Minimum Ionizing Particles. However, due to the high hygroscopicity susceptibility ion bombardment of CsI photocathodes, alternative photocathode materials are needed improve robustness MM. Diamond-like Carbon (DLC) film...
The ENUBET project recently concluded the R&D for a site independent design of monitored neutrino beam high precision cross section measurements, in which flux is inferred from measurement charged leptons an instrumented decay tunnel. In this phase three fundamental results were obtained and will be discussed here: 1) beamline not requiring horn relying on static focusing elements allows to perform $\nu_e$ DUNE energy range with 1% statistical uncertainty employing $10^{20}$ 400 GeV protons...
Abstract PICOSEC Micromegas (MM) is a precise timing gaseous detector based on Cherenkov radiator coupled with semi-transparent photocathode and an MM amplifying structure. The concept was successfully demonstrated through single-channel prototype, achieving sub-25 ps time resolution Minimum Ionizing Particles (MIPs). A series of studies followed, aimed at developing robust, large-area, scalable detectors high resolution, complemented by specialized fast-response readout electronics. This...
ENUBET has pioneered a novel technique to control the neutrino flux and flavor composition with percent-level precision. This successful R&D effort paved way for new generation of cross-section experiments designed meet precision requirements current oscillation studies. In this talk, we will summarize ENUBET's key achievements outline plans its implementation at CERN