Ioannis Madesis

Ioannis Madesis
National and Kapodistrian University of Athens | uoa · Department of Nuclear and Particle Physics

Ph.D. - Atomic/Molecular Physics

About

28
Publications
2,009
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65
Citations
Additional affiliations
December 2012 - present
University of Crete
Position
  • PhD Student
Description
  • Development and construction of a dedicated beam-line for experiments in Atomic Physics.
Education
October 2012 - July 2015
National Technical University of Athens
Field of study
  • Microelectronics and Nanodevices
September 2003 - October 2012
National Technical University of Athens
Field of study
  • Physics/Applied Sciences

Publications

Publications (28)
Article
Full-text available
The process of the capture of a target electron into the projectile continuum (ECC) is investigated both experimentally and theoretically for collisions of 1.25-6.00 MeV deuterons with multielectron gas targets. Double-differential cross sections (DDCS), d2σ/dωdE, of the ECC cusp-shaped electron peak involving He, Ne, and Ar gas targets were measur...
Article
Full-text available
The Tandem Accelerator Laboratory of NCSR “Demokritos,” Athens, Greece, is presented. A technical description of the laboratory, the installed setups together with currently implemented upgrades and associated funded projects are given. A few highlights as well as future upgrade plans and access possibilities to external users are also presented.
Article
This study focuses on the details of cascade repopulation of doubly excited triply open-shell C 3+ (1s2s2p) 4 P and 2 P ± states produced in 2-18 MeV collisions of C 4+ (1s2s 3 S) with He. Such cascade calculations are necessary for the correct determination of the ratio R of their cross sections, used as a measure of spin statistics [Madesis et al...
Article
Full-text available
We report on C3+(1s2ℓ2ℓ′ L2S+1)-resolved cross sections of electron capture in collisions of swift C4+(1s2s S3) ions with helium and hydrogen. The study focuses on the formation of doubly excited triply open-shell C3+(1s2s2p) P4 and P2± states with emphasis on the ratio R of their cross sections as a measure of spin statistics. Using zero-degree Au...
Article
Full-text available
Synopsis New state-resolved Li-like carbon Auger KLL measurements of mixed-state C ⁴⁺ (1s ² ¹ S, 1s2s ³ S) ions in 6-15 MeV collisions with He are presented. Results of three-electron semiclassical atomic orbital AOCC coupled channel (3eAOCC) calculations are also presented and compared.
Article
Full-text available
Auger KLn lines are observed in high‐resolution electron spectra obtained in collisions of mixed‐state (1s21S,1s2s3S) He‐like beams of 4 MeV B3+ with H2 and 6 MeV C4+ with He targets. Supporting atomic structure calculations show these lines to correspond to doubly excited states, which can be readily populated by electron transfer to the component...
Article
Full-text available
Normalized electron yields of the formation of 2s2p 3,1P states from the metastable states 1s2s 3,1S and from the ground state 1s21S were obtained in 6-18MeV C4+ collisions with H2, He, Ne and Ar gas targets. The method of zero-degree Auger projectile spectroscopy was used to detect electrons emitted in the Auger decay C4+ (2s2p 3,1P) → C5+ (1s) +...
Article
Full-text available
Single electron transfer to the 1s2s 3S long-lived component of the naturally occurring mixed-state(1s2, 1s2s 3S) C4+ion beam in collisions with gas targets was investigated using zero-degree Auger projectile spectroscopy at the Demokritos 5.5 MV tandem accelerator. The observed KLL Auger spectrum contains 1s2s2p 2P and 4P states resulting from dir...
Article
Full-text available
An experimental station has recently been completed with a beam line dedicated to atomic collision physics at the 5.5 MV TANDEM accelerator laboratory of the Institute of Nuclear and Particle Physics (INPP) at the National Center for Scientific Research (NCSR) “Demokritos” in Athens. A Zero-degree Auger Projectile Spectroscopy (ZAPS) apparatus comp...
Article
Full-text available
A gas stripper system has been installed inside the terminal of the Demokritos TANDEM accelerator, in addition to the existing foil stripper system, while two additional post strippers (one gas and one foil) were also installed in the beam line between the analyzing and switching magnets of the accelerator. These installations were necessary for th...
Article
Full-text available
The only existing heavy-ion accelerator in Greece, the 5.5 MV TANDEM at the National Research Center “Demokritos” in Athens has been used to date primarily for investigations centering around nuclear physics. Here, we propose to establish the new (for Greece) discipline of Atomic Physics with Accelerators, a strong field in the EU with important co...
Article
Full-text available
A new accelerator beam line dedicated to atomic collision physics has been constructed as part of the APAPES project that is being carried out at the TANDEM of the NCSR “Demokritos”. Interest in various charge states resulted in the design of a second stripping point after acceleration that was added to the main part of the TANDEM accelerator after...
Article
Full-text available
University of Crete (UoC) has initiated the research initiative APAPES funded by THALES‡ that has already set up a new experimental station with a beam line dedicated solely on basic atomic physics research. This new experiment utilizing Zero-degree Auger Projectile Spectroscopy (ΖΑPS) is located at the 5 MV TANDEM accelerator of the National Cente...
Article
Full-text available
The use of mixed-state ionic beams in collision dynamics investigations is examined. Using high resolution Auger projectile spectroscopy involving He-like ( 1 s 2 1 S , 1 s 2 s 3 , 1 S ) mixed-state beams, the spectrum contributions of the 1 s 2 s 3 S metastable beam component is effectively separated and clearly identified. This is performed with...
Preprint
Full-text available
The use of mixed-state ionic beams in collision dynamics investigations is examined. Using high resolution Auger projectile spectroscopy involving He-like ($1s^2\thinspace^1\!S, 1s2s\thinspace^{3,1}\!S$) mixed-state beams, the spectrum contributions of the $1s2s\thinspace^3\!S$ metastable beam component is effectively separated and clearly identifi...
Article
In zero-degree Auger projectile spectroscopy (ZAPS), electrons are measured with high energy resolution at 0° with respect to the beam direction and state-selective cross sections can be determined. However, for Auger electrons from long-lived projectile states such as the 1s2s2pPJ4 (with lifetimes ranging from ns to ms depending on atomic number Z...
Article
Full-text available
Effective solid angle correction factors for two high resolution electrostatic spectrometers - a hemispherical and a tandem parallel plate – are determined using SIMION Monte Carlo simulations. Results are compared to experimental correction factors directly determined from Auger spectra produced by 1s ionization in collisions of 6.6 MeV C²⁺ (1s²2s...
Article
The methodology and results of a detailed four-element lens optimization analysis based on electron trajectory numerical simulations are presented for a hemispherical deflector analyzer (HDA), whose entry aperture size is determined by the injection lens itself and is therefore virtual. Trajectory calculations were performed using both the boundary...
Article
Full-text available
We have recently build a new experimental station with a beam line dedicated to atomic collision physics at the 5 MV TANDEM accelerator of the Institute of Nuclear and Particle Physics at the National Research Center " Demokritos " in Athens, Greece. A complete zero-degree Auger projectile spectroscopy apparatus composed of a single stage hemispher...
Conference Paper
Full-text available
We have investigated the voltage settings for the 4-element injection lens of a biased paracentric hemispherical deflection analyzer (HDA) with virtual entry aperture using numerical methods. The two lens electrode voltages were varied as free parameters while the electron optical properties of the analyzer were calculated from trajectories with te...
Conference Paper
Full-text available
We present the unique benefits of gas and foil pre- and post- stripping in the production of pure ground state (1s?), as well as mixed (1s?, 1s2s) state He-like beams. The availability of such beams in TANDEM accelerators is of vital importance in studies concerning the population mechanisms of the 1s2s2p ?P metastable states produced in collisions...
Conference Paper
Full-text available
We investigate the energy resolution and line shape of a biased paracentric hemispherical deflector analyzer considering the distance between the exit focal plane and the detection plane. Equipped with a piezoelectrically controlled location of a 2D position sensitive detector we were able to accurately determine the optimum conditions for best ene...
Conference Paper
Full-text available
We demonstrate an experimental approach to the solid angle correction needed for the metastable 1s2s2p ^4P state obtained in ion-atom collisions with gaseous targets. By applying a small bias voltage VGC on the target gas cell, the ^4P contributions are separated into two peaks one arising from inside (which is shifted by e_{VGC}) and the other out...
Article
Full-text available
The Optimization of a 4-Element Input Lens on a Hemispherical Deflector Analyzer Using SIMION - Volume 21 Issue S4 - TJM Zouros, A. Kanellakopoulos, I. Madesis, A. Dimitriou, M. Fernández-Martín, G. Martinez, T.J. Mertzimekis
Article
Full-text available
We present SIMION 8.1 Monte Carlo type simulations of the response function and detection solid angle for long lived Auger states (lifetime τ ∼ 10−9 − 10−5 s) recorded by a hemispherical spectrograph with injection lens and position sensitive detector used for high resolution Auger spectroscopy of ion beams. Also included in these simulations for t...
Conference Paper
Full-text available
The new research initiative APAPES (http://apapes.physics.uoc.gr/) has already established a new experimental station with a beam line dedicated for atomic collisions physics research, at the 5 MV TANDEM accelerator of the National Research Centre "Demokritos" in Athens, Greece. A complete zero-degree Auger projectile spectroscopy (ZAPS) apparatus...

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Project
SEE http://apapes.physics.uoc.gr/