Magnetic bottle electron spectroscopy of atomic reactions triggered by a pulsed electron beamBarba, Žiga (Avtor) Žitnik, Matjaž (Mentor) electron spectroscopyTOF spectroscopyelectron-electron coincidencesIn the last 20–30 years the magnetic bottle electron spectrometer (MBES) has become a well established tool to research many-particle inner-shell vacancy decay by multi-electron coincidence methods in atoms and molecules. We report on a new version of such a spectrometer that we have designed at our laboratory where for the first time, instead of photons, electrons are used as the excitation source. This was achieved by positioning the electron source behind the permanent magnet setup aligning it parallel to the spectrometer axis which allowed 3–5 % of electrons to pass through a channel in the soft iron core that concentrates the magnetic field lines towards the target region achieving a magnetic field density of 600 mT. Short, nanosecond electron pulses, necessary for the operation of the spectrometer, were produced by sweeping the continuous beam across a narrow aperture at the electron source exit. Using numerical models we simulated how the different apparatus components would perform. These findings pointed out that careful alignment of all the components (the electron source, the permanent magnet set-up, the drift field and the electron detector) is crucial in optimizing the performance of the spectrometer. We report on the first experiment using the new spectrometer, where 800 eV electrons were scattered on argon. In the scattered, emitted and Auger electron kinetic spectra, which were calculated from electron time of flights, we can clearly distinguish several characteristic features: 3p and 2p ionization peaks and the L- MM Auger signal. From the results we estimate the energy resolution of 1.5 % after the electrons travel along the 2 m long drift tube. By analyzing two-, three- and four-electron coincidences we reduced the background further and resolved a few additional weaker spectral components that belong to more complex decay processes, such as the Coster-Kronig 2s vacancy decay, where the atom ejects four electrons with different energies in such a way, that the sum of their energies remains constant. Comparison to the theoretical BEB (Binary-encounter Bethe) scattering model showed agreement with our experimental data. The total electron detection efficiency $\eta \approx$ 0.23 was found to be constant in the investigated 0–0.8 keV energy range. This is somewhat lower than reported for other MBES set-ups where a practically 70 % efficiency is assumed. The discrepancy is most likely due to a relatively large target volume and the remaining spectrometer misalignment.20202020-10-13 12:07:37Doktorsko delo/naloga121519VisID: 113415COBISS_ID: 24015363sl