Niobium and Rhenium: Improved Binders for AMS
Dr Thomas Woodruff1, Dr. George Jackson1
1Prime Lab, West Lafayette, United States
In 2017 PRIME Lab began using a gas filled magnet (GFM) system for the measurement of 26Al. This enabled injection of the more prolific AlO- ion as opposed to Al-. Along with these higher beam currents came a lowering of the achievable blank. However, source memory was a much larger problem for 26Al versus 10Be. We have since switched to Nb as a binder for both Al2O3 and BeO. The reduction in source memory for 26Al was substantial and we now routinely run a machine blank with a ratio less than 1E-15 26Al/27Al even after measuring unknown samples with ratios greater than 1E-11 26Al/27Al. We have also begun using all Nb targets periodically during 36Cl runs to eliminate buildup of 36Cl source memory.
Another refractory metal introduced into our process is Re, used as a binder for CaF2. We found that using Re increased currents by 31% over Ag and we now routinely measure currents over 500 nA CaF-. This has increased performance for both our biomedical and extraterrestrial 41Ca programs.
Dr. Thomas Woodruff is Chief Accelerator Engineer and Data Scientist at the Purdue University Rare Isotope Measurement Lab in West Lafayette, IN USA. Thomas holds a PhD in physics from Purdue University with research interests that include particle detector development for accelerator mass spectrometry and cosmogenic radionuclides on the West Antarctic Ice Sheet. In his spare time Thomas enjoys listening to jazz, reading history, and wrangling cats.