Detection of ¹³⁵Cs by accelerator mass spectrometry

Abstract

The results demonstrate the feasibility of measuring long-lived Cs isotopes without Ba interference by AMS with on-line isobar separation and the ability to use shorter lived Cs isotopes for yield tracing.

Determination of 135Cs by accelerator mass spectrometry

“…The ISA was used to suppress the isobaric interferences from 134/135 Ba. Using 0.53 Pa of O 2 gas in the reaction cell of the ISA was found to be sufficient for removing Ba while maintaining a usable Cs signal [3].…”

“…However, since the established techniques rely on radiometric measurement of the Cs isotopes, new techniques for the measurement of 135 Cs must be developed because of its long half life (2.3 Ma) and pure beta emission. The first detection of 135 Cs by accelerator mass spectrometry (AMS) was accomplished using an Isobar Separator for Anions (ISA) which eliminated the ubiquitous Ba isobar interference in Cs samples [3][4][5]. ISA-AMS has the potential to enhance nuclear contamination forensics that has been pioneered using inductively coupled mass spectrometry (ICPMS) and chronometric tracing techniques proposed by Lee et al, and oceanic tracing techniques which thus far have relied on the shorter lived 137 Cs isotope.…”

Dynamics and reactivity of thermalized ions in a radiofrequency quadrupole gas-reaction cell used for the production of radioactive molecular ions

“…The system is differentially pumped to ensure a vacuum of 10 -6 mbar or less in the Einzel lens sections and about 5 x 10 -5 mbar in the central section surrounding the pressurized cell. The system is integrated into the injection beam line of the AMS system after the low energy mass selection magnet [1][2][3][4]8]. The dimensionless Mathieu parameters q and a describe the coupling of ions with the quadrupolar RF field generated inside the ion guide [10].…”

“…A large variety of chemical reactions between ions and neutral molecules can be accomplished in a pressurized radiofrequency quadrupole (RFQ) ion guide [1][2][3][4]. However, these reactions are highly dependent on the translational energy of ions when they interact with neutrals.…”

“…To obtain efficient chemical conversion, near thermal conditions must be achieved by combining electrostatic deceleration of ions, followed by collisions with a reactive or non-reactive gas near room temperature (~300 K). Approaches such as mounting the pressurized RFQ ion guide on a high voltage platform matching the energy of the incoming beam combined with the use of focusing and stopping electrodes, have successfully been applied in Accelerator Mass Spectrometry (AMS) to partially thermalize ions [1][2][3][4]. This approach enables the selective suppression of atomic isobars from several radionuclides of interest via highly specific ion-molecule reactions.…”