# Hannover 2020 – wissenschaftliches Programm

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# MS: Fachverband Massenspektrometrie

## MS 12: Accelerator Mass Spectrometry and Applications III

### MS 12.3: Vortrag

### Donnerstag, 12. März 2020, 14:30–14:45, f128

Towards the redetermination of the halflife of ^{32}Si - Equilibrium charge distributions of ^{28}Si in Ar — •Matthias Schlomberg, Christof Vockenhuber, and Hans-Arno Synal — Laboratory of Ion Beam Physics, ETH Zurich

The long-lived radionuclide ^{32}Si is a cosmogenic nuclide with potentially interesting applications for dating the recent past. However, its half-life of about 150 years is still not known with sufficient precision despite several independent measurements over the four decades. The SINCHRON collaboration with partners from PSI, CHUV, PTB and ETH aims at a comprehensive redetermination of the half-life of ^{32}Si. Laboratory of Ion Beam Physics at ETH Zurich will perform the AMS measurements for the determination of the number of ^{32}Si atoms in the samples used for the activity measurement. In addition to the challenge of the separation of ^{32}Si from the isobar ^{32}S, the absolute measurement is challenging, because no ^{32}Si standards are available.

Therefore, the equilibrium charge state distribution of ^{28}Si in Ar was measured in the energy range of 1-40 MeV using the external stripper at the TANDEM AMS facility. This information is necessary to find the optimal terminal voltage and for correction of mass fractionation in the stripping process.

In the first part of the presentation, the SINCHRON project will be introduced and motivated. Subsequently, our setup to measure the equilibrium charge distribution will be shown and the obtained data will be presented and discussed.