On-line ion chemistry for the AMS analysis of 90Sr and 135,137Cs

RFQ Reaction Cells for AMS: Developments and Applications

“…For samples for which no measures were taken to remove sulphur and no prior cleaning of the ion source which had been running S samples for the elemental tests, the level of 36 S background was calculated to be 3 x 10 -14 . More detailed descriptions of these measurements is provided in the PhD thesis of J. Eliades [16] Similar work followed for 90 Ba, using 133 Cs and 135 Ba difluoride anions [2]. Using the ISA alone, a suppression of yttrium with respect to strontium of 8 x 10 -5 and a suppression of zirconium with 03005-p.2 respect to strontium of 3 x 10 -6 were obtained.…”

“…For this gas, a laboratory energy of 10 eV corresponded to a centre of mass energy of 1.4 eV. At a cell pressure of 0.5 Pa, an acceleration gap between the cells of 9 V and a larger than usual voltage on the gradient electrodes in each cell, an attenuation factor of KF 3 -/CaF 3 -< 10 -5 was achieved [2]. With the implementation of proper segmented rods, it is expected that even more complete attenuation will be achieved.…”

“…Using the ISA alone, a suppression of yttrium with respect to strontium of 8 x 10 -5 and a suppression of zirconium with 03005-p.2 respect to strontium of 3 x 10 -6 were obtained. These ratios are further enhanced by the relative formation probability of the XF 3 -molecular anion in the ion source (where X is either Sr, Y or Zr) of 2 x 10 -5 for Y/Sr and 3 x 10 -5 for Zr/Sr [2,17]. Similarly, for barium with respect to strontium, the ISA provided a suppression of 2 x 10 -5 , which would be enhanced by a factor of 5 x 10 -4 for the formation of CsF 2 -over BaF 2 -in the ion source.…”

“…The use of anion-gas interactions in Radiofrequency Quadrupole (RFQ) ion guide reaction cells has been shown to be very effective in the elimination of a number of atomic and molecular isobars which have caused difficulties for Accelerator Mass Spectrometry (AMS) measurements [1,2]. This presentation begins with a review of the early work leading to the use of ion-gas reactions and continues with a discussion the recent measurements of the efficacy of this technique, some of which involve fluoride molecular anions.…”

Accelerator mass spectrometry – from DNA to astrophysics

“…This method looks promising to perform selective on-line ion chemistry with large suppression of unwanted stable isobars [17]. It will eventually also allow one to use small AMS facility where the isobar interferences must be removed at the injection side of the tandem accelerator.…”