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Half-Life

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Klaus Mayer - One of the best experts on this subject based on the ideXlab platform.

  • Remeasurement of 234U Half-Life
    Analytical chemistry, 2016
    Co-Authors: Zsolt Varga, Adrian Nicholl, Maria Wallenius, Klaus Mayer
    Abstract:

    The Half-Life of 234U has been measured using a novel approach. In this method, a uranium material was chemically purified from its thorium decay product at a well-known time. The ingrowth of the 230Th daughter product in the material was followed by measuring the accumulated 230Th daughter product relative to its parent 234U nuclide using inductively coupled plasma mass spectrometry. Then, the 234U decay constant and the respective Half-Life could be calculated using the radioactive decay equations based on the n(230Th)/n(234U) amount ratio. The obtained 234U Half-Life is 244 900 ± 670 years (k = 1), which is in good agreement with the previously reported results in the literature with comparable uncertainty. The main advantages of the proposed method are that it does not require the assumption of secular equilibrium between 234U and 238U. Moreover, the calculation is independent from the 238U Half-Life value and its uncertainty. The suggested methodology can also be applied for the remeasurement of the ...

  • Determination of the 229Th Half-Life
    Physical Review C, 2014
    Co-Authors: Zsolt Varga, Adrian Nicholl, Klaus Mayer
    Abstract:

    The paper describes the re-measurement of the Half-Life of 229Th (ground state). The Half-Life was obtained by the measurement of amount content of 229Th in the certified 229Th radioactivity standard (SRM 4328C) from National Institute of Standards and Technology. The measurement was performed by isotope dilution inductively coupled plasma mass spectrometry using two independent standards for quantification. From the results the 229Th Half-Life is determined to be 7917 years with an expanded uncertainty of 48 years using a coverage factor of k = 2. The methodology is traceable to SI and the calculation complies with the recommendations of Bureau International des Poids et Mesures (BIPM) for nuclear data evaluation.JRC.E.7-Nuclear Safeguards and Forensic

Zsolt Varga - One of the best experts on this subject based on the ideXlab platform.

  • Remeasurement of 234U Half-Life
    Analytical chemistry, 2016
    Co-Authors: Zsolt Varga, Adrian Nicholl, Maria Wallenius, Klaus Mayer
    Abstract:

    The Half-Life of 234U has been measured using a novel approach. In this method, a uranium material was chemically purified from its thorium decay product at a well-known time. The ingrowth of the 230Th daughter product in the material was followed by measuring the accumulated 230Th daughter product relative to its parent 234U nuclide using inductively coupled plasma mass spectrometry. Then, the 234U decay constant and the respective Half-Life could be calculated using the radioactive decay equations based on the n(230Th)/n(234U) amount ratio. The obtained 234U Half-Life is 244 900 ± 670 years (k = 1), which is in good agreement with the previously reported results in the literature with comparable uncertainty. The main advantages of the proposed method are that it does not require the assumption of secular equilibrium between 234U and 238U. Moreover, the calculation is independent from the 238U Half-Life value and its uncertainty. The suggested methodology can also be applied for the remeasurement of the ...

  • Determination of the 229Th Half-Life
    Physical Review C, 2014
    Co-Authors: Zsolt Varga, Adrian Nicholl, Klaus Mayer
    Abstract:

    The paper describes the re-measurement of the Half-Life of 229Th (ground state). The Half-Life was obtained by the measurement of amount content of 229Th in the certified 229Th radioactivity standard (SRM 4328C) from National Institute of Standards and Technology. The measurement was performed by isotope dilution inductively coupled plasma mass spectrometry using two independent standards for quantification. From the results the 229Th Half-Life is determined to be 7917 years with an expanded uncertainty of 48 years using a coverage factor of k = 2. The methodology is traceable to SI and the calculation complies with the recommendations of Bureau International des Poids et Mesures (BIPM) for nuclear data evaluation.JRC.E.7-Nuclear Safeguards and Forensic

Adrian Nicholl - One of the best experts on this subject based on the ideXlab platform.

  • Remeasurement of 234U Half-Life
    Analytical chemistry, 2016
    Co-Authors: Zsolt Varga, Adrian Nicholl, Maria Wallenius, Klaus Mayer
    Abstract:

    The Half-Life of 234U has been measured using a novel approach. In this method, a uranium material was chemically purified from its thorium decay product at a well-known time. The ingrowth of the 230Th daughter product in the material was followed by measuring the accumulated 230Th daughter product relative to its parent 234U nuclide using inductively coupled plasma mass spectrometry. Then, the 234U decay constant and the respective Half-Life could be calculated using the radioactive decay equations based on the n(230Th)/n(234U) amount ratio. The obtained 234U Half-Life is 244 900 ± 670 years (k = 1), which is in good agreement with the previously reported results in the literature with comparable uncertainty. The main advantages of the proposed method are that it does not require the assumption of secular equilibrium between 234U and 238U. Moreover, the calculation is independent from the 238U Half-Life value and its uncertainty. The suggested methodology can also be applied for the remeasurement of the ...

  • Determination of the 229Th Half-Life
    Physical Review C, 2014
    Co-Authors: Zsolt Varga, Adrian Nicholl, Klaus Mayer
    Abstract:

    The paper describes the re-measurement of the Half-Life of 229Th (ground state). The Half-Life was obtained by the measurement of amount content of 229Th in the certified 229Th radioactivity standard (SRM 4328C) from National Institute of Standards and Technology. The measurement was performed by isotope dilution inductively coupled plasma mass spectrometry using two independent standards for quantification. From the results the 229Th Half-Life is determined to be 7917 years with an expanded uncertainty of 48 years using a coverage factor of k = 2. The methodology is traceable to SI and the calculation complies with the recommendations of Bureau International des Poids et Mesures (BIPM) for nuclear data evaluation.JRC.E.7-Nuclear Safeguards and Forensic

G.w. Kolnicki - One of the best experts on this subject based on the ideXlab platform.

T H Sinks - One of the best experts on this subject based on the ideXlab platform.

  • Half-Life of polybrominated biphenyl in human sera.
    Environmental health perspectives, 1995
    Co-Authors: D H Rosen, W D Flanders, A Friede, Harold E.b. Humphrey, T H Sinks
    Abstract:

    Polybrominated biphenyl (PBB), a flame-retardant material, was introduced into the food chain in Michigan in 1973 due to a manufacturing and distribution mistake. Following public concern about the long-term health effects of PBB in humans, a cohort of PBB-exposed Michigan residents was assembled in 1975. We initiated this study to determine the Half-Life of PBB in human sera and to understand how continued body burden relates to the possible adverse health consequences of PBB exposure. To determine the Half-Life, eligible persons were selected from the cohort if they had at least two PBB measurements 1 year apart and had an initial level > or = 20 pbb. There were 163 persons who met the criteria with a median PBB level of 45.5 ppb. The estimated Half-Life is 10.8 years (95% CI, 9.2-14.7 years). The body burden of PBB in exposed persons will decrease only gradually over time. For persons with an initial level of 45.5 ppb of PBB, it will take more than 60 years for their PBB levels to fall below the current level of detection of 1 ppb.