First 10Be measurements at Trondheim 1 MV AMS

The performance of the Trondheim 1 MV AMS system for Be measurements has been investigated. While the initial acceptance tests were done using the 1 + 1+ charge state, we concluded that the 2 + 2+ charge state offers superior measurement conditions. With this setting, the source-to-detector efficiency is 5.4 ± 0.2% and a Be/Be background level of 3.4 ± 0.8·10 was achieved. Standard samples (n = 14) with a high Be content of Be/Be = 2.7·10 could be reproduced to a 0.4% precision, leaving counting statistics as the limiting uncertainty for most samples. The accuracy of the system was also tested using 5 secondary standards of different Be content. The results corroborate the precision achieved with the standard sample and demonstrate the accuracy of the system.Peer reviewe

Radiocarbon calibration around AD 1900 from Scots pine (Pinus sylvestris) tree rings from northern Norway

To resolve an inconsistency around AD 1895 between radiocarbon (14C) measurements on oak from the British Isles and Douglas fir and Sitka spruce from the Pacific Northwest, USA, we measured the 14C content in single-year tree rings from a Scots pine tree (Pinus sylvestris L.), which grew in a remote location in Saltdal, northern Norway. The dataset covers the period AD 1864–1937 and its results are in agreement with measurements from the US Pacific coast around 1895. The most likely explanation for older ages in British oak in this period seems to be 14C depletion associated with the combustion of fossil fuels

The 1953-1965 rise in atmospheric bomb 14C in central Norway

Sub-annual measurements, eight increments per year, of cellulose in a Scots pine tree growing in central Norway are presented as a proxy for tropospheric 14CO2 at biweekly to monthly resolution. The results are validated by comparison to direct atmospheric measurements in the years 1959–1965, and a new dataset is obtained for 1953–1958. In this period, our cellulose measurements deviate from the Bomb 13 NH1 calibration curve, which is derived from single-year measurements of tree rings. This is due to seasonal cycles in tropospheric radiocarbon (14C) concentrations, caused by the first series of atmospheric nuclear weapons tests

Status Report of the Trondheim Radiocarbon Laboratory

The Trondheim radiocarbon (14C) laboratory has evolved from a traditional radiocarbon decay counting laboratory to an accelerator mass spectrometry (AMS) facility primarily measuring 14C. This evolution required adjustments in sample preparation and data handling to match the capacity of the AMS system and reduction in sample sizes to about 1 mgC. We summarize here the steps involved in dating a sample at the National Laboratory for Age Determination in Trondheim, Norway. These include the structure of our sample database for information handling, sample cleaning procedures for different sample types, our reduction systems, both an automated EA-based system for regular use and a manual system for more challenging samples, and data evaluation. We will also briefly summarize the capabilities of our isotope-ratio mass spectrometer