Rutte, Daniel; Pfänder, Jörg A; Koleška, Michal; Jonckheere, Raymond; Unterricker, Sepp (2014): Metallic Fluence Monitors and J-value standards [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.836880,

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Supplement to: Rutte, D et al. (2015): Radial fast-neutron fluence gradients during rotating 40Ar/39Ar sample irradiation recorded with metallic fluence monitors and geological age standards. Geochemistry, Geophysics, Geosystems, 16(1), 336-345, https://doi.org/10.1002/2014GC005611

Utilizing the neutron-irradiation parameter J is one of the major uncertainties in 40Ar/39Ar dating. The associated error of the individual J-value for a sample of unknown age depends on the accuracy of the age of the geological standards, the fast-neutron fluence distribution in the reactor and the distances between standards and samples during irradiation. While it is generally assumed that rotating irradiation evens out radial neutron fluence gradients, we observed axial and radial variations of the J-values in sample irradiations in the rotating channels of two reactors. To quantify them, we included three-dimensionally distributed metallic fast- (Ni) and thermal- (Co) neutron fluence monitors in three irradiations and geological age standards in three more. Two irradiations were carried out under Cd-shielding in the FRG1 reactor in Geesthacht, Germany, and four without Cd-shielding in the LVR-15 reactor in Řež, Czech Republic. The 58Ni(nf,p)58Co activation reaction and γ-spectrometry of the 811 keV peak associated with the subsequent decay of 58Co to 58Fe allow to calculate the fast-neutron fluence. The fast-neutron fluences at known positions in the irradiation container correlate with the J-values determined by mass-spectrometric 40Ar/39Ar measurements of the geological age standards. Ra-dial neutron fluence gradients are up to 1.8 %/cm in FRG1 and up to 2.2 %/cm in LVR-15; the corre-sponding axial gradients are up to 5.9 and 2.1 %/cm. We conclude that sample rotation might not al-ways suffice to meet the needs of high-precision dating and gradient monitoring can be crucial.

The .zip-archive contains the data of 40Ar/39Ar analyses and gammaspetrometric analyses related to sample irradiations FGA002, FGA003, FGA012, FGA014, FGA015, FGA016 in reactors FRG1 and LVR-15. Argon data are reported following the norms of Renne et al. [2009]. Gammaspectrometric analyses are saved in the .sp1 format of GammaVision software Version 5.10. Ni stands for Nickel foil, Co for Co foil. The position of both metallic and geological age standards is given by the first number giving the disk/plate number and the second the number of the individual hole. Coordinates and an evaluation of the data are given in the Supporting Information of the related article.