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  • 1.
    DiJulio, D. D.
    et al.
    European Spollat Source ERIC, POB 176, SE-22100 Lund, Sweden;Lund Univ, Div Nucl Phys, SE-22100 Lund, Sweden.
    Cooper-Jensen, Carsten P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. European Spollat Source ERIC, POB 176, SE-22100 Lund, Sweden.
    Llamas-Jansa, I.
    European Spollat Source ERIC, POB 176, SE-22100 Lund, Sweden;Inst Energy Technol, POB 40, N-2027 Kjeller, Norway.
    Kazi, S.
    Inst Energy Technol, POB 40, N-2027 Kjeller, Norway.
    Bentley, Phillip M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. European Spollat Source ERIC, POB 176, SE-22100 Lund, Sweden.
    Measurements and Monte-Carlo simulations of the particle self-shielding effect of B4C grains in neutron shielding concrete2018In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 147, p. 40-44Article in journal (Refereed)
    Abstract [en]

    A combined measurement and Monte-Carlo simulation study was carried out in order to characterize the particle self-shielding effect of B4C grains in neutron shielding concrete. Several batches of a specialized neutron shielding concrete, with varying B4C grain sizes, were exposed to a 2 angstrom neutron beam at the R2D2 test beamline at the Institute for Energy Technology located in Kjeller, Norway. The direct and scattered neutrons were detected with a neutron detector placed behind the concrete blocks and the results were compared to Geant4 simulations. The particle self-shielding effect was included in the Geant4 simulations by calculating effective neutron cross-sections during the Monte-Carlo simulation process. It is shown that this method well reproduces the measured results. Our results show that shielding calculations for low-energy neutrons using such materials would lead to an underestimate of the shielding required for a certain design scenario if the particle self shielding effect is not included in the calculations.

  • 2.
    Grusell, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Section of Medical Physics.
    On the definition of absorbed dose2015In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 107, p. 131-135Article in journal (Refereed)
    Abstract [en]

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before. (C) 2014 Elsevier Ltd. All rights reserved.

  • 3.
    Pokapanich, Wandared
    et al.
    Nakhon Phanom Univ, Fac Sci, Nakhon Phanom 48000, Thailand..
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Öhrwall, Gunnar
    Lund Univ, Max Lab, POB 118, SE-22100 Lund, Sweden..
    Tchaplyguine, Maxim
    Lund Univ, Max Lab, POB 118, SE-22100 Lund, Sweden..
    Core level photoelectron spectroscopy probed heterogeneous xenon/neon clusters2017In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 135, p. 45-48Article in journal (Refereed)
    Abstract [en]

    Binary rare gas clusters; xenon and neon which have a significant contrariety between sizes, produced by a co-expansion set up and have been studied using synchrotron radiation based x-ray photoelectron spectroscopy. Concentration ratios of the heterogeneous clusters; 1%, 3%, 5% and 10% were controlled. The core level spectra were used to determine structure of the mixed cluster and analyzed by considering screening mechanisms. Furthermore, electron binding energy shift calculations demonstrated cluster aggregation models which may occur in such process. The results showed that in the case of low mixing ratios of 3% and 5% of xenon in neon, the geometric structures exhibit xenon in the center and xenon/neon interfaced in the outer shells. However, neon cluster vanished when the concentration of xenon was increased to 10%.

  • 4.
    Vasilopoulou, T.
    et al.
    NCSR Demokritos, Inst Nucl & Radiol Sci, Technol Energy & Safety, Athens, Greece..
    Stamatelatos, I. E.
    NCSR Demokritos, Inst Nucl & Radiol Sci, Technol Energy & Safety, Athens, Greece..
    Batistoni, P.
    ENEA, Fus Tech Unit, Rome, Italy..
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Obryk, B.
    Polish Acad Sci, Inst Nucl Phys, Krakow, Poland..
    Popovichev, S.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England..
    Syme, D. B.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England..
    Neutron streaming along ducts and labyrinths at the JET biological shielding: Effect of concrete composition2015In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 116, p. 359-364Article in journal (Refereed)
    Abstract [en]

    Experiments and Monte Carlo simulations were performed at the Joint European Torus (JET) in order to validate the computational tools and methods applied for neutron streaming calculations through penetrations in the JET Hall biological shielding. In the present work the sensitivity of the simulations on the hydrogen and boron content in concrete shielding was investigated. MCNP code was used to simulate neutron streaming along the JET Hall personnel entrance labyrinth for deuterium-deuterium and deuterium-tritium plasma sources for different concrete wall compositions. Neutron fluence and ambient dose equivalent along the labyrinth were calculated. Simulation results for the "as built" JET concrete composition were compared against measurements performed using thermoluminescence detectors. This study contributes to the optimization of the radiation shielding of JET and, furthermore, provides information from JET experience that may assist in optimizing and validating the radiation shielding design methodology used in its successor fusion devices ITER and DEMO.

  • 5. Wolska, A.
    et al.
    Klepka, M. T.
    Lawniczak-Jablonska, K.
    Misiuk, A.
    Arvanitis, Dimitri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Structural and magnetic properties of Mn(+) implanted silicon crystals studied using X-ray absorption spectroscopy techniques2011In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 80, no 10, p. 1119-1124Article in journal (Refereed)
    Abstract [en]

    The implantation of Mn ions into two Si substrates with different doping (P or B), resistivity and oxygen content was performed at low and high substrate temperatures. Different post-implantation processing was carried out to study its influence on the structural and magnetic properties of these samples. The local order around the Mn atoms was characterized by X-ray absorption fine structure techniques and the magnetic properties of the Mn ionic cores were determined by means of X-ray magnetic circular dichroism measurements. The results are discussed in relation to the structural and macroscopic magnetic properties. It is shown that the amorphous matrix speeds up the formation of MnSi(x) inclusions. However, the existence of inclusions or the type of electrically active dopants is not directly related to the magnetic properties. Therefore, in the performed studies, the importance of structural defects on the magnetic properties was confirmed. A localized magnetic moment carried by the Mn ionic cores could not be detected by means of dichroic measurements.

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