Isobar separation of ⁹³Zr and ⁹³Nb at 24 MeV with a new multi-anode ionization chamber

Author(s)

Martin Martschini, Josef Buchriegler, Philippe Collon, Walter Kutschera, Johannes Lachner, Wenting Lu, Alfred Priller, Peter Steier, Robin Golser

Abstract

⁹³Zr with a half-life of 1.6 Ma is produced with high yield in nuclear fission, and thus should be present as a natural or anthropogenic trace isotope in all compartments of the general environment. Sensitive measurements of this isotope would immediately find numerous applications, however, its detection at sufficiently low levels has not yet been achieved. AMS measurements of

⁹³Zr suffer from the interference of the stable isobar

⁹³Nb. At the Vienna Environmental Research Accelerator VERA a new multi-anode ionization chamber was built. It is optimized for isobar separation in the medium mass range and is based on the experience from AMS experiments of

³⁶Cl at our 3-MV tandem accelerator facility. The design provides high flexibility in anode configuration and detector geometry. After validating the excellent energy resolution of the detector with

³⁶S, it was recently used to study iron-nickel and zirconium-niobium-molybdenum isobar separation. To our surprise, the separation of

⁹⁴Zr (Z = 40) from

⁹⁴Mo (Z = 42) was found to be much better than that of

⁵⁸Fe (Z = 26) from

⁵⁸Ni (Z = 28), despite the significantly larger ΔZ/Z of the latter pair. This clearly contradicts results from SRIM-simulations and suggests that differences in the stopping behavior may unexpectedly favor identification of

⁹³Zr. At 24 MeV particle energy, a

⁹³Nb (Z = 41) suppression factor of 1000 is expected based on a synthetic

⁹³Zr spectrum obtained by interpolation between experimental spectra from the two neighboring stable isotopes

⁹²Zr and

⁹⁴Zr. Assuming realistic numbers for chemical niobium reduction, a detection level of

⁹³Zr/Zr below 10

^-9 seems feasible.

Organisation(s)

Isotope Physics

External organisation(s)

Helmholtz-Zentrum Dresden-Rossendorf, University of Notre Dame

Journal

Nuclear Instruments & Methods in Physics Research. Section B. Beam Interactions with Materials and Atoms

Volume

361

Pages

201-206

No. of pages

6

ISSN

0168-583X

DOI

https://doi.org/10.1016/j.nimb.2015.03.061

Publication date

10-2015

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics

Keywords

ASJC Scopus subject areas

Nuclear and High Energy Physics, Instrumentation

Portal url

https://ucris.univie.ac.at/portal/en/publications/isobar-separation-of-93zr-and-93nb-at-24-mev-with-a-new-multianode-ionization-chamber(a64f932d-0b7d-4542-9422-eb65c386375d).html