Browsing by Author "Hult, M"

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    Analysis of compound semiconductor materials using heavy ion recoil spectrometry
    (Australian and New Zealand Institutes of Physics, 1994-11-09) Walker, SR; Johnston, PN; Bubb, IF; Studd, W; Cohen, DD; Dytlewski, N; Hult, M; Whitlow, HJ; Zahring, C; Östling, M; Andersson, M; Martin, JW
    Heavy Ion Recoil Spectrometry has been used to examine various semiconductor material systems which cannot easily be studied using convensional ion beam techniques such as RBS. The technique enables the determination of seperate energy spectra for individual elements. This enables it to be used in many situations where RBS is inappropriate due to the superimposition of signals in the backscattering spectrum. We have employed Recoil Spectrometry to study; light element impurity concentrations, stoiciometry and metalisation contact systems for various compound semiconductor materials.- The experiments were performed at the ANTARES (TN Tandem) accelerator facillity at Lucas Heights using 61-91 MeV 12?I ions jn e incident " ' i ions cause nuclei of the sample to recoil following Rutherford scattering. The recoiling target nuclei are then analysed by a Time Of Flight and Energy (TOF-E) detector telescope composed of two timing pickoff detectors and a surface barrier (energy) detector. From the time of flight and energy, the ion mass can be determined and individual depth distributions for each element can be obtained.
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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 I: alpha decay
    (IOP Publishing, 2016-11-28) Pommé, S; Stroh, H; Paepen, J; Van Ammel, R; Marouli, M; Altzitzoglou, A; Hult, M; Kossert, K; Nähle, O; Schrader, H; Juget, F; Bailat, C; Nedjadi, Y; Bochud, F; Buchillier, T; Michotte, M; Courte, S; van Rooy, MW; van Staden, MJ; Lubbe, L; Simpson, BRS; Fazio, A; De Felice, D; 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, M; Korun, M; Chisté, V; Amiot, MN
    Claims that proximity to the Sun causes variation of decay constants at permille level have been investigated for alpha decaying nuclides. Repeated decay rate measurements of 209Po, 226Ra, 228Th, 230U, and 241Am sources were performed over periods of 200 d up to two decades at various nuclear metrology institutes around the globe. Residuals from the exponential decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ in amplitude and phase from one data set to another and appear attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of α decaying sources set an upper limit between 0.0006% and 0.006% 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. Oscillations in phase with Earth's orbital distance to the sun could not be observed within 10−5–10−6 range precision. © The Authors CC BY 3.0 licence
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    On decay constants and orbital distance to the Sun—part II: beta minus decay
    (IOP Publishing, 2016-11-28) Pommé, S; Stroh, H; Paepen, J; Van Ammel, R; Marouli, M; Altzitzoglou, A; Hult, M; Kossert, K; Nähle, O; Schrader, H; Juget, F; Bailat, C; Nedjadi, Y; Bochud, F; Buchillier, T; Michotte, M; Courte, S; van Rooy, MW; van Staden, MJ; Lubbe, L; Simpson, BRS; Fazio, A; De Felice, D; 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, M; Korun, M; Chisté, V; Amiot, MN
    Claims that proximity to the Sun causes variations of decay constants at the permille level have been investigated for beta-minus decaying nuclides. Repeated activity measurements of 3H, 14C, 60Co, 85Kr, 90Sr, 124Sb, 134Cs, 137Cs, and 154Eu sources were performed over periods of 259 d up to 5 decades at various nuclear metrology institutes. Residuals from the exponential decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ in amplitude and phase 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− decaying sources set an upper limit of 0.003%–0.007% 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
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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