Performance of the ETH gas ionization chamber at low energy

The performance of gas ionization chambers (GIC) for the detection of low energy ions has been considerably improved in the past years by the use of silicon nitride entrance windows and low noise preamplifiers. This has led to an increased use of high resolution GICs in the fields of accelerator mass spectrometry and ion beam analysis. This development and the underlying physical principles are reviewed and the latest technical status of such devices is summarized.A detailed study on energy resolution and pulse height defect is presented with projectiles covering a wide particle mass range (H, 9Be, 13C, 27Al, 35Cl, 127I, 232Th) with energies between 0.1 and 2.2 MeV. The dependence of energy resolution and charge output per unit particle energy on the nuclear charge of the projectile is investigated and parametrized. SRIM calculations of ionizing energy loss considerably differ from these experimental findings. For 1 MeV particles discrepancies up to 50% are observed.The performance of GICs and their practical use is compared to that of solid state detectors. The potential for further improvement of the technology and its fields of application are assessed.