Pushing the limits of 41Ca AMS with CaF2 targets at DREAMS

The performance of 41Ca measurements at the 6 MV AMS system at HZDR, DREAMS (DREsden AMS) was improved in terms of overall efficiency and suppression of interfering isobar 41K. Mixing CaF2 samples not only with Ag, but also with PbF2 increases the negative ionization efficiency by a factor 3, from 0.15% to 0.45%. This option is dedicated to low level samples because ion source parameters have to be lowered, which increases the measurement time. In general, 41K-suppression factor of the detector is improved from 2 x 104 to 4 x 104 by advances in the analysis of the spectra. With such improvements, a 95% confidence level (C.L.) sensitivity for the 41Ca/40Ca ratio of 2 x 10-15 can be achieved at DREAMS.

Automated summary

The performance of 41Ca measurements at DREAMS was improved in terms of overall efficiency and suppression of interfering isobar 41K. Mixing CaF2 samples with Ag and PbF2 increased the negative ionization efficiency by a factor 3. This improvement allows for a 95% confidence level sensitivity of 41Ca/40Ca ratio of 2 x 10-15 to be achieved at DREAMS.