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Träfflista för sökning "WFRF:(Äystö Juha) "

Search: WFRF:(Äystö Juha)

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1.
  • Ekman, Jörgen, et al. (author)
  • Retention of Pb isotopes in glass surfaces for retrospective assessment of radon exposure
  • 2006
  • In: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 249:1-2, s. 544-547
  • Journal article (peer-reviewed)abstract
    • In recent years there has been increasing interest in radio-epidemiological techniques to retrospectively measure the radon dose exposure by determining the activity of 210Pb, the longest-lived 222Rn progeny, in glass surface layers. In this study the diffusion of 39 keV 209Pb+ ions implanted into glass using the IGISOL facility has been studied under conditions that mimic the recoil implantation of 210Pb from 222Rn. The resulting depth distributions of 209Pb were then measured after heat treatment in vacuum at different temperatures by a sputter erosion technique. The diffusion coefficient could be described by an Arrhenius equation D = D0exp(−H/kT) where and H = 2.81 ± 0.11 eV. No statistically significant loss of 209Pb from the sample was observed for annealing between 470 and 600 °C.
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2.
  • Solders, Andreas, 1976- (author)
  • Precision mass measurements : Final limit of SMILETRAP I and the developments of SMILETRAP II
  • 2011
  • Doctoral thesis (other academic/artistic)abstract
    • The subject of this thesis is high-precision mass-measurements performed with Penning trap mass spectrometers (PTMS). In particular it describes the SMILETRAP I PTMS and the final results obtained with it, the masses of 40Ca and that of the proton. The mass of 40Ca is an indispensible input in the evaluation of measurements of the bound electron g-factor, used to test quantum electrodynamical calculations in strong fields. The value obtained agrees with available literature values but has a ten times higher precision.The measurement of the proton mass, considered a fundamental physical constant, was performed with the aim of validating other Penning trap results and to test the limit of SMILETRAP I. It was also anticipated that a measurement at a relative precision close to 10-10 would give insight in how to treat certain systematic uncertainties. The result is a value of the proton mass in agreement with earlier measurements and with an unprecedented precision of 1.8×10-10.Vital for the achieved precision of the proton mass measurement was the use of the Ramsey excitation technique. This technique, how it was implemented at SMILETRAP I and the benefits from it is discussed in the thesis and in one of the included papers.The second part of the thesis describes the improved SMILETRAP II setup at the S-EBIT laboratory, AlbaNova. All major changes and upgrades compared to SMILETRAP I are discussed. This includes, apart from the Ramsey excitation technique, higher ionic charge states, improved temperature stabilization, longer run times, different reference ions, stronger and more stable magnetic field and a more efficient ion detection. Altogether these changes should reduce the uncertainty in future mass determinations by an order of magnitude, possibly down to 10-11.
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