Browsing by Author "Jull, AJT"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Exposure history of the Torino meteorite
    (Wiley, 1996-03) Wieler, R; Graf, T; Signer, P; Vogt, S; Herzog, GF; Tuniz, C; Fink, D; Fifield, LK; Klein, J; Middleton, R; Jull, AJT; Pellas, P; Masarik, J; Dreibus, G
    We determined He, Ne, Ar, 10Be, 26Al, 36Cl, and 14C concentrations, as well as cosmic-ray track densities and halogen concentrations in different specimens of the H6 chondrite Torino, in order to constrain its exposure history to cosmic radiation. The Torino meteoroid had a radius of ∼20 cm and travelled in interplanetary space for 2.5–10 Ma. Earlier, Torino was part of a larger body. The smallest possible precursor had a radius of 55 cm and a journey through space longer than ∼65 Ma. If the first-stage exposure took place in a body with a radius of >3 m or in the parent asteroid, then it lasted nearly 300 Ma. The example of Torino shows that it is easy to underestimate first-stage exposure ages when constructing two-stage histories. © 1999-2021 John Wiley & Sons, Inc.
  • No Thumbnail Available
    Item
    New extraction line for the in-situ C-14 at HEKAL AMS laboratory
    (Goldschmidt, 2022-07-14) Buró, B; Fülöp, RH; Jull, AJT; Molnar, M
    In this study we presented a new cosmogenic in-situ C-14 extraction line at the ICER laboratory, which is similar to be published in Fülöp et al. [1]. These extraction system used the phase transformation of quartz to cristobalite on high temperature in order to quantitatively extract the carbon as CO2. The system consists of three independent components. 1: used for remove the atmospheric and meteoric C-14, 2: offline high-temperature (1650 °C) oven for extract and trapped the cosmogenic in-situ 14C from quartz, 3: CO2 gas purification and mass measurement line. After the extraction and cleaning, the purified CO2 samples are measured with compact 14C AMS system (Environ MICADAS) and the gas ion source interface. The extraction line allows for rapid sample throughput of about 6 samples per week. The sample masses ranging between 4 and 7 g of clean quartz. Our first tests were on the borehole CO2 blank gas and Cronus standards. The blank level of the whole line is very low. We get similar experiences and results as Fülöp et al. [1]. Purified quartz samples were sieved and used for analyse the fraction of 250 – 500 µm. The carbon yield from quartz samples are very good and we have the expected values. The research was supported by the European Union and the State of Hungary. co-financed by the European Regional Development Fund in the project of GINOP-2.3.4-15-2020-00007 “INTERACT”. [1] Fülöp et al. (2019) Nuclear Inst. and Methods in Physics Research B 438, 207-213.