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Identifier 000438345
Title Investigation of electron capture in swift C4+ (1s2s 3S) collisions with gas targets using a zero-degree Auger projectile spectroscopy apparatus built with the L45 beam line at the “Demokritos” 5.5MV tandem accelerator.
Alternative Title Διερεύνηση της σύλληψης ηλεκτρονίου σε κρούσεις ταχέων C 4+ (1s2s 3S) ιόντων µε αέριους στόχους, χρησιµοποιώντας τη διάταξη ϕασµατοσκοπίας Auger ηλεκτρονίων ιόντων στις 0◦ που κατασκευάστηκε µε τη γραµµή L45 στον 5.5 MV tandem επιταχυντή του ΕΚΕΦΕ “∆ηµόκριτος”.
Author Μαδέσης, Ιωάννης Μ.
Thesis advisor Τζούρος, Θεώδορος
Abstract This thesis focuses primarily on the investigation of the collision process: C4+ (1s2s 3S) + T → C3+(1s2s2p 4P, 2P ±) + T+ |→ C4+(1s 2 ) + eA‘ in which a highly-charged (He-like) beam of C4+ ions in the long-lived metastable state (1s2s 3S) energetically collide with gas targets (He, H2). In the collision an electron from the target is captured by the 2p orbital of the carbon ion (a process known as electron transfer) in the process giving rise to the production of Li-like doubly-excited states 1s2s2p 4P (a spin quartet), 1s(2s2p 3P) 2P− (for short as 2P−) and 1s(2s2p 1P) 2P+ (for short as 2P+), both spin doublets, as well as many other levels to be discussed later. This collision process can be readily investigated experimentally since the initial, 1s2s 3S, ionic core is metastable1 and therefore naturally found mixed-in with the 1s 2 ground state ions as provided by accelerators. One of the main interests in the aforementioned process has to do with the question of whether the similarly configured 1s2s2p 4P and 2P± states are populated in the collision according to spin statistics, i.e. in the ratio R of their spin degeneracies of quartets to doublets. The concept of spin statistics is of fundamental interest since most collision processes are assumed to obey spin statistics. In fact, the above process was found not to obey spin statistics as first exposed in 2004 [2,3] for fluorine He-like ions (F7+) leading to controversial claims and results [4–6]. In this thesis, the Single Differential Cross-Section (SDCS), dσ(θ)/dΩ, is determined for each of these 1s2s2p produced levels using the high resolution projectile Auger electron spectroscopy technique known as Zero-degree Auger Projectile Spectroscopy (ZAPS), i.e. where the emitted projectile Auger electron eA is observed at the angle of θ = 0◦ with respect to the beam direction. Towards this purpose, a new, dedicated beam line (L45), together with a unique, state-of-the-art ZAPS experimental setup was built from scratch, at the only heavy ion research accelerator in Greece, the 5.5 MV tandem Van de Graaff accelerator (for short tandem), operated since 1972 by the INPP of the NCSR, in Athens. Furthermore, this new Atomic Physics initiative involved non-trivial changes to the existing hardware and mode of operation of the tandem accelerator itself, used primarily for Nuclear Physics investigations involving mostly proton beams. Experimental results utilizing the ZAPS technique, regarding relative populations of quartet and doublet states were found to be in agreement with earlier corrected measurements [6]. At the same time, ab initio dynamical calculations have been performed by the theory group of Prof. Alain Dubois - UPMC-Sorbone and CNRS Paris, involving for the first time three active electrons. These results, presented in Ref. [7], resolve the previously existing disagreement between theory and experiment and draw attention to the limited predictive power of the frozen core approximation as regards to spin statistics in highly correlated dynamical atomic systems.
Language English
Subject Accelerator-based atomic physics
Alkali vapors
Atomic magnetometry
Atomic physics
Auger electron spectroscopy
Aτοµική ϕυσική µε επιταχυντές
Cascades
Doubly-excited states
Dual-species
Electron capture (single electron transfer)
Entanglement in spin exchange collisions
He-like ions
Highly-charged ions
Ion-atom collisions
Li-like ions
Long-lived (metastable) states
Mixed-state ion beams
Precision measurements
Projectile-ion electron spectroscopy
Quantum metrology
Quantum physics
Quantum sensing
Quantum trajectories
Spin statistics
State-selective cross sections
Διπλά διεγερµένες καταστάσεις
Ηλιοειδή ιόντα
Ιοντικές δέσµες µεικτών καταστάσεων
Κρούσεις ιόντων ατόµων
Λιθιοειδή ιόντα
Μακρόβιες (µετασταθείς) καταστάσεις
Σπιν στατιστική
Σύλληψη ηλεκτρονίου (µονή µεταφορά ηλεκτρονίου)
Σύμπλεξη στις συγκρούσεις ανταλλαγής σπιν
Τροφοδοσία αλληλουχίας
Υψηλα ϕορτισµένα ιόντα
Φασµατοσκοπία ηλεκτρονίων ιόντων δέσµης
Φασµατοσκοπία ηλεκτρονίων ιόντων δέσµης στις 0◦
Issue date 2021-04-12
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/c/a/8/metadata-dlib-1615891163-364125-10309.tkl Bookmark and Share
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