Accelerator mass spectrometry at VERA

Fig.1: Overview of long-lived radionuclides

Fig. 2: Overview of the VERA facility

  • A balance between technical developments and demanding applications is very important at VERA (Vienna Environmental Research Accelerator). The applications reach into many areas of our environment, from archaeology to climate research. Special emphasis is placed on AMS applications within physics, i.e. astrophysics, nuclear physics, atomic and molecular physics. One focus of our technical developments is to extend the limits of the AMS method, e.g. the accuracy, reliability and sample size for the most important AMS isotope 14C. Another emphasis is the detection of the heaviest radioisotopes (233U, 236U, 244Pu). We are working to enable accelerator mass spectrometry of radioisotopes in the whole range of the nuclide map (Fig. 1, Golser et al., 2017).
  • VERA is an accelerator facility optimized for Accelerator Mass Spectrometry (AMS). The actual accelerator is a 3MV pelleton tandem accelerator from the National Electrostatics Corporation (NEC), USA. The facility went into operation in 1996 and was extended in 2001 and 2016 to allow accelerator mass spectrometry of radioisotopes in the whole range of the nuclide chart and the separation of isobars using a self-developed facility for ion-laser interaction (ILIAMS, below).
  • The figure 2 shows the facility with its two ion sources and the ILIAMS setup, the injector magnet and, after the tandem accelerator, analytical elements such as the magnetic analyzer, the electrostatic analyzer and the detectors for various AMS applications.
  • If you are interested in a guided tour at VERA laboratory, you can find all the relevant information here.

ILIAMS

  • Ion Laser InterAction Mass Spectrometry (ILIAMS) is a new kind of element-selective filter currently developed and explored at VERA. It is the first device of its kind worldwide coupled to an AMS-facility. ILIAMS utilizes selective laser photodetachment of cooled anions to efficiently remove disturbing ion species from the anion beam. In order to achieve the required ion laser interaction times of ~1ms, the anion beam is cooled in a buffer-gas-filled radiofrequency ion guide, where it is overlapped with a strong cw laser beam of appropriate wavelength. Thanks to ILIAMS, more and more new trace isotopes become for the first time accessible to AMS at environmental levels. Recent additions include the long-lived fission products 90Sr (highest sensitivity of any detection technique worldwide) 135Cs and 137Cs. Currently we are working hard to add the astrophysically interesting 182Hf (Astrophysics).