Deep underground gamma spectrometric measurement of 26Al in meteorite samples

26Al is routinely measured in meteorite samples by accelerator mass spectrometry (AMS). PTB participates in an international intercomparison between laboratories using AMS and gamma-ray spectrometry to improve the quality of such measurements. We performed gamma spectrometric measurements at the underground laboratory UDO using the GESPECOR software to calculate corrections for efficiency transfer, self-attenuation and coincidence summing. Four meteorite samples were measured for more than 30 days each but nevertheless, the uncertainty budgets are dominated by the uncertainties of the count rates.