Preliminary tests of 26Al fluoride target matrix on AMS system
Kateřina Fenclová1, Tomas Prasek1, Marcus Christl2, Philip Gautschi2, Christof Vockenhuber2
1Department of Nuclear Chemistry, Czech Technical University in Prague, Czech Republic, 2Laboratory of Ion Beam Physics, ETH Zürich
The performance of the fluoride materials using a superhalogenide ion AlF4- extracted from Na3AlF6 based target materials for 26Al/27Al measurements was tested on the 0.3 MV MILEA AMS. Routine AMS measurements of 26Al/27Al are often performed by using Al2O3 target samples and extracting the negative Al-ions from the ion source. In that case, a 26Mg isobar is suppressed as magnesium does not form sufficiently stable negative ions. However, the intensity of the Al- currents is significantly lower compared to molecular ions like AlO-, which cannot be generally used for analysis due to the formation of the molecular isobar 26MgO-.
In this study, a fluoride matrix utilization for 26Al measurements was investigated initially in a caesium sputtering ion source and low energy side of the HVE Tandetron system at NPI Rez, Czech Republic, and subsequently on the MILEA AMS system at ETH Zürich. The AlF4- current was used to evaluate the performance of the respective samples. Additives as PbF2 were tested to increase the extracted ion currents and samples containing MgF2 were used to investigate the presence of isobaric ions and the ionization efficiency of AlF4- was determined by recording the 27Al2+ current on the high energy side. The signals of 26Al2+ were investigated with the gas ionization detector. It was realized that aluminium fluoride matrix provides significantly more intense ion beam of AlF4- ion than Al- and AlO- from Al2O3 matrix but possible interferences from magnesium and cathode material were identified.
Katerina Fenclova, Ph.D. student of nuclear chemistry, Czech Technical University in Prague. I focus mainly on development and preparation of fluoride target matrices for AMS measurement of 239Pu and other actinides, as well as cosmogenic nuclides, their chemical separation and pre-concentration from natural samples.