AMS with a 14 million volt accelerator – Mn-53 and Fe-60 with ANU’s ENGE
Prof. Anton Wallner1,2, Prof. LK Fifield1, Michaela B. Froehlich1, Dominik Koll1,2, Guy Leckenby1,3, Martin Martschini1,4, Stefan Pavetich1, Stephen G. Tims1, Dorothea Schumann5, Zuzana Slavkovská1
1The Australian National University, Canberra, Australia, 2Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, 3present address: University of British Columbia, TRIUMF, Vancouver, Canada, 4present address: University of Vienna, Faculty of Physics, VERA Laboratory, Vienna, Austria, 5Biology and Chemistry, Paul Scherrer Institute (PSI), Villigen, Switzerland
AMS at ANU’s Department of Nuclear Physics and Accelerator Applications is based on a 14UD tandem accelerator. The 14UD has demonstrated exceptional accelerator performance over more than 3 decades of AMS, e.g. by running regularly above 14 MV. Sadly, but perhaps inevitably, a number of similar nuclear physics facilities have been lost to closure due to aging equipment and high operational costs. The aim of this paper is to showcase the actual performance and potential of an indeed older but definitely not obsolete AMS facility, demonstrating the continuing need for specialised high-energy systems.
The measurement program at the Heavy Ion Accelerator Facility (HIAF) has always been strong on environmental, safeguards and geological research. Several nuclear astrophysics projects were also added over the past 10 years as a major research topic. This system operates with particle energies between ~24 MeV (actinides) and >200 MeV (e.g. ⁵³Mn, ⁹³Zr).
The focus here will be on the AMS performance utilizing HIAF’s unique setup of high particle energies combined with an ENGE split-pole spectrograph that has been converted into a gas-filled magnet (GFM) as a means for providing an efficient reduction of isobaric background. ANU’s ENGE has been in use as a GFM now for more than 20 years, first for ³²Si and then for ⁵³Mn in geology. However, more recently, a set of additional isotopes has been added and to support these projects a new flexible multi-anode ion chamber was constructed:
• ⁶⁰Fe: this isotope – mainly of interest to astrophysics, e.g. the search for recent nearby Super-nova explosions – has become one of the dominant isotopes within ANU’s measurement program. Background-free measurement (equivalent to ⁶⁰Fe/Fe<3×10^-¹⁷) has been demonstrated.
• ⁵³Mn: more difficult to measure than ⁶⁰Fe, this nuclide is of interest to nuclear astrophysics as well as for geological applications. Both applications require a measurement sensitivity that challenges even HIAF’s present capabilities.
• Other nuclides measured with the ENGE include ³²Si, ⁵⁹Ni and ⁹³Zr. In addition, ¹⁰Be and ²⁶Al, both extracted as oxides, achieve lower background or higher measurement efficiency when using the ENGE, as already demonstrated at other facilities, e.g. TU Munich and PRIME lab.
The potential of the ENGE for isobaric suppression and more generally HIAF’s measurement sensitivity and accuracy will be exemplified using ⁶⁰Fe and ⁵³Mn. We will give an overview of recent research activities, ongoing discussions on the half-life values, standard materials used and we will summarize ANU’s performance parameters of the above mentioned other isotopes.
Biographies to come