Search results for "Atomic physics"
showing 10 items of 5530 documents
Formation of dislocations and hardening of LiF under high-dose irradiation with 5–21 MeV 12C ions
2017
R. Zabels, I. Manika, J. Maniks, and R.Grants acknowledge the national project IMIS2, and A. Dauletbekova, M. Baizhumanov, and M. Zdorovets the Ministry of Education and Science of the Republic of Kazakhstan for the financial support.
First experiments on applying the gasdynamic ECR ion source for negative hydrogen ion production
2017
This article has no abstract. peerReviewed
Injected 1+ ion beam as a diagnostics tool of charge breeder ECR ion source plasmas
2015
International audience; Charge breeder electron cyclotron resonance ion sources (CB-ECRIS) are used as 1+ →n+ charge multiplication devices of post-accelerated radioactive ion beams. The charge breeding process involves thermalization of the injected 1+ ions with the plasma ions in ion–ion collisions, subsequent ionization by electron impact and extraction of the n+ ions. Charge breeding experiments of 85Rb and 133Cs ion beams with the 14.5 GHz PHOENIX CB-ECRIS operating with oxygen gas demonstrate the plasma diagnostics capabilities of the 1+ injection method. Two populations can be distinguished in the m/q-spectrum of the extracted ion beams, the low (1+ and 2+) charge states repres…
MeV-energy Xe ion-induced damage in LiF: The contribution of electronic and nuclear stopping mechanisms
2016
The contribution of electronic and nuclear damage mechanisms in the modification of structure and micromechanical properties of LiF crystals irradiated with 52, 224, and 450 MeV Xe ions at fluences 1010–1014 ions cm−2 has been studied. The ion-induced formation of dislocations and hardening in LiF at fluences above 1010 ions cm−2 has been observed. The depth profiles of nanoindentation show a joint contribution of electronic excitation and nuclear (impact) mechanisms to the ion-induced hardening. The electronic excitation mechanism dominates in the major part of the ion range while the impact mechanism prevails in a narrow zone at the end of the ion range. The efficiency of hardening produc…
Arsenic diffusion in relaxedSi1−xGex
2003
The intrinsic As diffusion properties have been determined in relaxed ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ epilayers. The properties were studied as a function of composition x for the full range of materials with $x=0,$ 0.20, 0.35, 0.50, 0.65, 0.8, and 1. The activation enthalpy ${E}_{a}$ was found to drop systematically from 3.8 eV $(x=0)$ to 2.4 eV $(x=1).$ Comparisons with other impurity atom- and self-diffusion results in Si, Ge, and SiGe show that both interstitials and vacancies contribute as diffusion vehicles in the composition range $0l~xl~0.35$ and that vacancy mechanism dominates diffusion in the composition range $0.35lxl~1.$
A quartz amplifier for high-sensitivity Fourier-transform ion-cyclotron-resonance measurements with trapped ions
2019
Single-ion sensitivity is obtained in precision Penning-trap experiments devoted to light (anti)particles or ions with low mass-to-charge ratios, by adding an inductance coil to an amplifier connected to the trap, both operated at 4 K. However, single-ion sensitivity has not been reached on heavy singly or doubly charged ions. In this publication, we present a new system to reach this point, based on the use of a quartz crystal as an inductance, together with a newly developed broad-band (BB) amplifier. We detect the reduced-cyclotron frequency of 40Ca+ ions stored in a 7-tesla open-ring Penning trap. By comparing the detected electric signal obtained with the BB amplifier and the fluoresce…
Experimental evidence on photo-assisted O− ion production from Al2O3 cathode in cesium sputter negative ion source
2020
The production of negative ions in cesium sputter ion sources is generally considered to be a pure surface process. It has been recently proposed that ion pair production could explain the higher-than-expected beam currents extracted from these ion sources, therefore opening the door for laser-assisted enhancement of the negative ion yield. We have tested this hypothesis by measuring the effect of various pulsed diode lasers on the O − beam current produced from Al 2O 3 cathode of a cesium sputter ion source. It is expected that the ion pair production of O − requires populating the 5d electronic states of neutral cesium, thus implying that the process should be provoked only with specific …
Photoelectron Emission from Metal Surfaces Induced by VUV-emission of Filament Driven Hydrogen Arc Discharge Plasma
2015
Photoelectron emission measurements have been performed using a filament-driven multi-cusp arc discharge volume production H^- ion source (LIISA). It has been found that photoelectron currents obtained with Al, Cu, Mo, Ta and stainless steel (SAE 304) are on the same order of magnitude. The photoelectron currents depend linearly on the discharge power. It is shown experimentally that photoelectron emission is significant only in the short wavelength range of hydrogen spectrum due to the energy dependence of the quantum efficiency. It is estimated from the measured data that the maximum photoelectron flux from plasma chamber walls is on the order of 1 A per kW of discharge power.
Operating a cesium sputter source in a pulsed mode
2020
A scheme is presented for pulsing of a cesium sputter negative ion source by periodically switching on and off the high voltage driving the sputtering process. We demonstrate how the pulsed ion beam can be used in combination with a pulsed laser (6 ns pulse length) that has a 10 Hz repetition rate to study the photodetachment process, where a negative ion is neutralized due to the absorption of a photon. In such experiments, where the ion beam is used only for a small fraction of the time, we show that the pulsed mode operation can increase the lifetime of a cathode by two orders of magnitude as compared with DC operation. We also investigate how the peak ion current compares with the ion c…
A new 18 GHz room temperature electron cyclotron resonance ion source for highly charged ion beams
2020
An innovative 18 GHz HIISI (Heavy Ion Ion Source Injector) room temperature Electron Cyclotron Resonance (ECR) ion source (ECRIS) has been designed and constructed at the Department of Physics, University of Jyväskylä (JYFL), for the nuclear physics program of the JYFL Accelerator Laboratory. The primary objective of HIISI is to increase the intensities of medium charge states (M/Q ≅ 5) by a factor of 10 in comparison with the JYFL 14 GHz ECRIS and to increase the maximum usable xenon charge state from 35+ to 44+ to serve the space electronics irradiation testing program. HIISI is equipped with a refrigerated permanent magnet hexapole and a noncylindrical plasma chamber to achieve very stro…