Evidence of 11-year solar cycles in tree rings from 1010 to 1110 AD – Progress on high precision AMS measurements

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 294; pp. 459 - 463
• Main Authors: Güttler, D., Wacker, L., Kromer, B., Friedrich, M., Synal, H.-A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2013
• Subjects: 14C; 14CO2; Accelerators; Age; AMS; Calibration; Calibration curve; Modulation; Offsets; Radioactive age determination; Radiocarbon ages; Solar cycle; Solar cycles; Solar forcing; Tree rings; 14C; Radiocarbon ages; Solar forcing; Calibration curve; AMS; 14CO2; Solar cycle
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2012.08.046

Oak tree rings from Southern Germany covering the AD 1010–1110years have been analyzed for radiocarbon with accelerator mass spectrometry (AMS) at the laboratory at ETH Zurich. High-precision measurements with a precision down to 12years radiocarbon age and a time resolution of 2years aimed to identify modulations of the 14C concentration in tree ring samples caused by the 11years solar cycles, a feature that so far is not visible in the IntCal calibration curve. Our results are in good agreement with the current calibration curve IntCal09. However, we observed an offset in radiocarbon age of 25–40years towards older values. An evaluation of our sample preparation, that included variations of e.g.: chemicals, test glasses and processing steps did not explain this offset. The numerous measurements using the AMS-MICADAS system validated its suitability for high precision measurements with high repeatability.