Browsing by Author "Michotte, C"

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    Activity measurements of the radionuclide 153Sm for the ANSTO, Australia in the ongoing comparison BIPM.RI(II)-K1.Sm-153
    (Institute of Physics, 2005-01-01) Ratel, G; Michotte, C; Reinhard, MI; Alexiev, D; Mo, L
    In 2004, the Australian Nuclear Science and Technology Organisation (ANSTO) submitted two samples of known activity of 153Sm to the International Reference System (SIR). The value of the activity submitted was about 920 MBq. This key comparison result has been added to the matrix of degrees of equivalence in the key comparison database that now contains five results, identifier BIPM.RI(II)-K1.Sm-153. © 2005, Institute of Physics
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    APMP comparison of the activity measurements of Ba-133 (APMP.RI(II)-K2.Ba-133) and links to the SIR
    (Institute of Physics, 2009-01-01) Yunoki, A; Mo, L; Shaha, VV; Kartubi, N; van Wyngaardt, WM; Yuan, MC; Nhan, DD; Park, TS; Yuandi, Y; Soodprasert, T; Michotte, C
    The international comparison of radioactivity measurements of 133Ba (APMP.RI(II)-K2.Ba-133) was carried out within the framework of the Asia-Pacific Metrology Programme (APMP). In total, ten institutes took part in the comparison, and five institutes undertook absolute measurements. Nine of the results agreed with each other within their specified uncertainties. The source from the same radioactive solution that was used in the comparison was sent to the BIPM/SIR in order to link this regional comparison to the BIPM key comparison reference value (KCRV). The degrees of equivalence between the APMP comparison and the other measurements for 133Ba are presented. © 2009, Institute of Physics
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    Evidence against solar influence on nuclear decay constants
    (Elsevier B. V., 2016-10-10) Pommé, S; Stroh, H; Paepen, J; Van Ammel, R; Marouli, M; Altzitzoglou, T; Hult, M; Kossert, K; Nähle, O; Schrader, H; Juget, F; Bailat, CJ; Nedjadi, Y; Bochud, F; Buchillier, T; Michotte, C; Courte, S; van Rooy, MW; van Staden, MJ; Lubbe, J; Simpson, BRS; Fazio, A; De Felice, P; Jackson, TW; van Wyngaardt, WM; Reinhard, MI; Golya, J; Bourke, S; Roy, T; Galea, R; Keightley, JD; Ferreira, KM; Collins, SM; Ceccatelli, A; Unterweger, MP; Fitzgerald, R; Bergeron, DE; Pibida, L; Verheyen, L; Bruggeman, M; Vodenik, B; Korun, M; Chisté, V; Amiot, MN
    The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth's orbital distance to the Sun could not be observed within a to range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards. © 2016 The Authors. Published by Elsevier B.V.
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    On decay constants and orbital distance to the Sun—part III: beta plus and electron capture decay
    (IOP Publishing, 2016-11-28) Pommé, S; Stroh, H; Paepen, J; Van Ammel, R; Marouli, M; Altzitzoglou, T; Hult, M; Kossert, K; Nähle, O; Schrader, H; Juget, F; Bailat, C; Nedjadi, Y; Bochud, F; Buchillier, T; Michotte, C; Courte, S; van Rooy, MW; van Staden, MJ; Lubbe, J; Simpson, BRS; Fazio, A; De Felice, P; Jackson, TW; van Wyngaardt, WM; Reinhard, MI; Golya, J; Bourke, S; Roy, T; Galea, R; Keightley, JD; Ferreira, KM; Collins, SM; Ceccatelli, A; Verheyen, L; Bruggeman, M; Vodenik, B; Korun, M; Chisté, V; Amiot, MN
    The hypothesis that seasonal changes in proximity to the Sun cause variation of decay constants at permille level has been tested for radionuclides disintegrating through electron capture and beta plus decay. Activity measurements of 22Na, 54Mn, 55Fe, 57Co, 65Zn, 82+85Sr, 90Sr, 109Cd, 124Sb, 133Ba, 152Eu, and 207Bi sources were repeated over periods from 200 d up to more than four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and appear attributable to instabilities in the instrumentation and measurement conditions. Oscillations in phase with Earth's orbital distance to the sun could not be observed within 10−4–10−5 range precision. The most stable activity measurements of β+ and EC decaying sources set an upper limit of 0.006% or less to the amplitude of annual oscillations in the decay rate. There are no apparent indications for systematic oscillations at a level of weeks or months. © The Authors CC BY 3.0 licence