Single-pass non-destructive electronic detection of charged particles

Abstract

We have devised an experimental method and apparatus for the simultaneous nondestructive determination of the absolute ion number, ion kinetic energy, and length of bunches of charged particles. We have built and operated a corresponding electronic detector that is based on induced charges and their subsequent low-noise amplification at cryogenic temperatures. We have performed measurements with bunches of low-energy highly charged ions from an electron-beam ion source that show the capability of the methods and their implementation. We discuss requirements for, and applications of, such detectors with a particular view on the obtainable information and their sensitivity.

High-intensity laser experiments with highly charged ions in a Penning trap

“…From the time signal at the MCP we deduce the number of extracted ions, as the area below the signal is directly proportional to the number of ions. We have proven this dependence with a non-destructive single-pass charge counter whose signal height (U plat ) is known to be linearly dependent on the number of particles as well [34]. To determine the time-dependence of the number of stored ions, we have acquired a time-of-flight spectrum each 30s, evaluated the evolution of the C 2+ -signal (see figure 7(b)) in the time-of-flight spectrum and obtained the time evolution of the relative number of ions ejected from the trapping region.…”

“…The ion bunch properties, such as kinetic energy, ion number and bunch length can be deduced from the charge-counter signal shown in figure 5(b) (blue curve) by the evaluation of the plateau amplitude U plat , the area below the signal and the slope of the rising edge. The detailed procedure to obtain these quantities is described in [34]. With this procedure, we have been able to obtain a kinetic energy of the ion bunch below 100 eV/q and an axial extension of less than 50 mm.…”

Position-sensitive non-destructive detection of charged-particle bunches in low-energy beamlines

“…2 , with the voltage starting at zero when the particle is (infinitely) far away, reaching a maximum at the axial centre of the detection electrode pair and dropping to zero again. The knowledge of the geometry function can be used to measure the bunch length, as has been detailed in 21 .…”

“…Similar methods are also in use for dedicated measurements of particle mass 20 . Recently, a system and method has been devised that in addition to particle kinetic energy and particle number allows for a determination of axial bunch extension from a single-pass non-destructive measurement 21 .…”

Production of highly charged ions inside a cryogenic Penning trap by electron-impact ionisation

“…Depending on the charge state under consideration, the highly charged ions may be produced by various methods, most of which rely on an external source, combined with subsequent transport and capture into a Penning trap [15][16][17][18]. In contrast to singly charged ions, medium and high charge states cannot be efficiently produced by photo-ionisation inside the trap, as the required intensities are far beyond readily available lasers.…”