| 1. |
- Belonoshko, Anatoly B., et al.
(författare)
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Molecular dynamics study of phase transitions in Xe
- 2002
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 117:15, s. 7233-7244
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Tidskriftsartikel (refereegranskat)abstract
- A full account is given of our recent theoretical discovery [A. B. Belonoshko, R. Ahuja, and B. Johansson, Phys. Rev. Lett. 87, 165505 (2001)] of the fcc-bcc transition in Xe at high pressure and temperature. The interaction model and method for calculating phase boundaries are exhaustively tested by independent methods. The model was carefully checked against experimental data and results of ab initio molecular dynamics and it was found to perform very well. The two-phase method employed for finding the melting transition was compared with the robust thermodynamic approach and was found to provide data in exact agreement with the latter. The deviation of the calculated melting curve from the experimental one is quite tolerable at low pressures. After a reinterpretation of the experimental data, our results are also in good agreement with recent diamond anvil cell experiments. At a pressure of around 25 GPa and a temperature of about 2700 K, we find a triple fcc-bcc-liquid point. The fcc-bcc boundary is calculated without reference to the experimental data, in contrast to our previous work, and found to be in nice agreement with previous calculations as well as with the experimental data points, which, however, were interpreted as melting. Our finding concerning the fcc-bcc transition is confirmed by the direct molecular dynamics simulation of the fcc, bcc, and liquid phases in the same computational cell. In this simulation, it was observed that while the fcc phase melts, the bcc structure solidifies. Since Xe is a typical rare-gas solid, the fcc-bcc transition can now be expected for a number of other van der Waals systems, first of all in Ar and Kr. Our finding suggests, that the transition from close packed to bcc structure might be more common at high pressure and high temperature than was previously anticipated. The performed thorough test of methods and models in this study leads us to suggest that the original interpretation of experimental results is erroneous.
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| 2. |
- Broggio, D., et al.
(författare)
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Child and adult thyroid monitoring after a reactor accident (CAThyMARA): Technical recommendations and remaining gaps
- 2019
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 128:Septemberg
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier Ltd Following a severe nuclear reactor accident large amounts of radioactive iodine are released in the atmosphere. Health consequences estimation for the affected population is based on the dose assessment which can be derived from in vivo measurements. Since the uptake of radioactive iodine increases the thyroid cancer risk of children it is of particular interest to dispose of technical recommendations on thyroid monitoring, particularly for children. This paper summarizes recommendations that have been issued by a group of European radiation protection specialists during the CAThyMARA project. It covers technical aspects such as the choice of instruments, the calibration process, the measurement preparedness, the dose assessment and communication issues. This paper also discusses remaining gaps and serves as an introduction to other papers of this special issue.
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| 3. |
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| 4. |
- Lebacq, A L, et al.
(författare)
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European intercomparison on the measurement of l-131 in thyroid of adults and children.
- 2019
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 129
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Tidskriftsartikel (refereegranskat)abstract
- In case of a nuclear reactor accident affecting a large population the internal contamination of the workers and the public can be assessed through in vivo measurements. Since iodine-131 is one of the most important releases and since it is of health concern, thyroid monitoring of this radionuclide is of special interest. Intercomparisons of thyroid in vivo measurements usually focus on the adult case. Here we report about a European intercomparison exercise for spectroscopic devices. Three sets of thyroid phantoms of unknown activity were circulated, representing the following ages: 5 years-old, 10 years-old and the adult. Nineteen institutions from twelve countries in Europe took part in an intercomparison exercise. Twenty-nine measurement devices have been tested. In the adult case, 5 results were outside the acceptance criteria and 10 in the 10-years old case. In the 5 years-old case, the result was not reported for one measurement device and 11 results were outside the acceptance criteria. Devices that have been tested during this intercomparison now dispose of calibration coefficients for the three age groups.
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