PL EN


Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników
Czasopismo
2003 | 1 | 2 | 210-234
Tytuł artykułu

The effective absorption cross-section of thermal neutrons in a medium containing strongly or weakly absorbing centres

Treść / Zawartość
Warianty tytułu
Języki publikacji
EN
Abstrakty
EN
The structure of a heterogeneous system influences diffusion of thermal neutrons. The thermal-neutron absorption in grained media is considered in the paper. A simple theory is presented for a two-component medium treated as grains embedded in the matrix or as a system built of two types of grains (of strongly differing absorption cross-sections). A grain parameter is defined as the ratio of the effective macroscopic absorption cross-section of the heterogeneous medium to the absorption cross-section of the corresponding homogeneous medium (consisting of the same components in the same proportions). The grain parameter depends on the ratio of the absorption cross-sections and contributions of the components and on the size of grains. The theoretical approach has been verified in experiments on prepared dedicated models which have kept required geometrical and physical conditions (silver grains distributed regularly in Plexiglas). The effective absorption cross-sections have been measured and compared with the results of calculations. A very good agreement has been observed. In certain cases the differences between the absorption in the heterogeneous and homogeneous media are very significant. A validity of an extension of the theoretical model on natural, two-component, heterogeneous mixtures has been tested experimentally. Aqueous solutions of boric acid have been used as the strongly absorbing component. Fine- and coarse-grained pure silicon has been used as the second component with well-defined thermal-neutron parameters. Small and large grains of diabase have been used as the second natural component. The theoretical predictions have been confirmed in these experiments.
Wydawca

Czasopismo
Rocznik
Tom
1
Numer
2
Strony
210-234
Opis fizyczny
Daty
wydano
2003-06-01
online
2003-06-01
Twórcy
  • The Henryk Niewodniczański Institute of Nuclear Physics, ul. Radzikowskiego 152, 31-342, Kraków, Poland
  • The Henryk Niewodniczański Institute of Nuclear Physics, ul. Radzikowskiego 152, 31-342, Kraków, Poland
  • The Henryk Niewodniczański Institute of Nuclear Physics, ul. Radzikowskiego 152, 31-342, Kraków, Poland
autor
  • The Henryk Niewodniczański Institute of Nuclear Physics, ul. Radzikowskiego 152, 31-342, Kraków, Poland
  • The Henryk Niewodniczański Institute of Nuclear Physics, ul. Radzikowskiego 152, 31-342, Kraków, Poland, Urszula.Woznicka@ifj.edu.pl
Bibliografia
  • [1] K.H. Beckurts, K. Wirtz: Neutron Physics, Springer, Berlin, 1964.
  • [2] J.A. Czubek, Drozdowicz, B. Gabańska, A. Igielski, E. Krynicka-Drozdowicz, U. Woźnicka: “Advances in absolute determination of the rock matrix absorption cross section for thermal neutrons”, Nucl. Geophys., Vol. 5, (1991) pp. 101–107.
  • [3] K.M. Case, F. Hoffmann, G. Placzek: Introduction to the Theory of Neutron Diffusion. Vol. I. Los Alamos Scientific Laboratory, 1953.
  • [4] J. Molina, M.C. Lopes: “The effect of scattering on thermal neutron self-shielding factors of infinite cylindrical probes”, Kerntechnik, Vol. 51, (1987), pp. 194–196.
  • [5] J. Molina, M.C. Lopes: “A new approach to the neutron self-shielding factor with multiple scattering”, Kerntechnik, Vol. 52, (1988), pp. 197–199.
  • [6] J.A. Czubek, K. Drozdowicz, B. Gabańska, A. Igielski, E. Krynicka, U. Woźnicka: “Thermal neutron macroscopic absorption cross section measurement applied for geophysics”, Progress in Nucl. Energy, Vol. 30, (1996), pp. 295–303. http://dx.doi.org/10.1016/0149-1970(95)00091-7[Crossref]
  • [7] K. Drozdowicz, B. Gabańska, E. Krynicka: “Fitting the decaying experimental curve by a sum of exponentials”, In: Rept. INP No. 1635/AP, Institute of Nuclear Physics, Kraków, 1993.
  • [8] U. Woźnicka: “Solution of the thermal neutron diffusion equation for a two-region system by perturbation calculation”, J. Phys. D: Appl. Phys., Vol. 14, (1981), pp. 1167–1182. http://dx.doi.org/10.1088/0022-3727/14/7/006[Crossref]
  • [9] K. Drozdowicz, U. Woźnicka: “Energy corrections in pulsed neutron measurements for cylindrical geometry”, J. Phys. D: Appl. Phys, Vol. 16, (1983), pp. 245–254. http://dx.doi.org/10.1088/0022-3727/16/3/007[Crossref]
  • [10] K. Drozdowicz, U. Woźnicka: “High-precision thermal neutron diffusion parameters for Plexiglas”, J. Phys. D: Appl. Phys., Vol. 20, (1987), pp. 985–993. http://dx.doi.org/10.1088/0022-3727/20/8/001[Crossref]
  • [11] E. Krynicka, K. Drozdowicz, B. Gabańska, W. Janik, J. Dabrowska: “Measurements of the thermal neutron absorption ∑a of model systems (reference KCl solutions) in two-region geometry”, In: Rept. INP No. 1857/PN Institute of Nuclear Physics, Kraków, 2001,http://www.ifj.edu.pl/reports/bib2001.html
  • [12] K. Drozdowicz, E. Krynicka, U. Woźnicka, A. Igielski, A. Kurowski: “The thermal neutron absorption of mixtures of hydrogenous and non-hydrogenous substances measured in two-region geometry”, Rept. INP No. 1891/PN, Institute of Nuclear Physics, Kraków, 2001,http://www.ifj.edu.pl/reports/bib2001.html
  • [13] Krynicka-E. Drozdowicz: “Standard deviation of the intersection point for two statistically uncertain curve”, Rept. INP No. 1212/PM, Institute of Nuclear Physics, Kraków, 1983.
  • [14] S.F. Mughabghab, M. Divadeenam, N.E. Holden: “Neutron Cross Sections”, Neutron Resonance Parameters and Thermal Cross Sections, Vol. 1. Part A., Academic Press, New York, 1981.
  • [15] K. Drozdowicz, B. Gabańska, A. Igielski, E. Krynicka, U. Woźnicka: “A pulsed measurement of the effective thermal neutron absorption cross-section of a heterogeneous medium”, Ann. Nucl. Energy, Vol. 28, (2001), pp. 519–530. http://dx.doi.org/10.1016/S0306-4549(00)00071-2[Crossref]
  • [16] K. Drozdowicz: “The diffusion cooling coefficient for thermal neutrons in Plexiglas”, J. Phys. D: Appl. Phys., Vol. 31, (1998), pp. 1800–1807. http://dx.doi.org/10.1088/0022-3727/31/15/006[Crossref]
  • [17] J.R. Granada: “Slow-neutron scattering by molecular gases: A synthetic scattering function”, Phys. Rev., Vol. B 31, (1985), pp. 4167–4177. http://dx.doi.org/10.1103/PhysRevB.31.4167[Crossref]
  • [18] J.R. Granada, V.H. Gillette: “A review of a synthetic scattering function approach to the thermal and cold neutron scattering kernels of moderator materials”, J. Neutr. Research, Vol. 7, (1999), pp. 75–85.
  • [19] K. Drozdowicz: “Thermal neutron diffusion parameters dependent on the flux energy distribution in finite hydrogenous media”, Rept. INP No. 1838/PN, Institute of Nuclear Physics, Kraków, 1999.
  • [20] E. Krynicka, B. Gabańska, U. Woźnicka, M. Kosik-Abramczyk: “Measurements of the thermal neutron absorption ∑a of boron of unknown isotopic ratio”, Rept. INP No. 1860/PN, Institute of Nuclear Physics, Kraków, 2000, http://www.ifj.edu.pl/reports/bib2000.html
  • [21] K. Drozdowicz, E. Krynicka: “Thermal neutron diffusion parameters in homogeneous mixtures”, Répt. INP No. 1694/PN, Institute of Nuclear Physics., Kraków, 1995.
  • [22] U. Woźnicka, E. Krynicka, K. Drozdowicz, M. Kosik, W. Janik: “Influence of granulation of the diabase sample on the thermal neutron ∑a measurement”, Rept. INP No. 1893/PN, Institute of Nuclear Physics, Kraków, 2001, http://www.ifj.edu.pl/reports/2001.html
  • [23] B. Gabańska, E. Krynicka, U. Woźnicka: “Effect of a crushing degree of the rock sample on the thermal neutron absorption cross section measurement”, Nafta-Gaz, Vol. 5, (2002), pp. 231–239.
  • [24] A. Polański, K. Smulikowski: Geochemia, Wyd. Geologiczne, Warszawa, 1969, pp. 60.
Typ dokumentu
Bibliografia
Identyfikatory
Identyfikator YADDA
bwmeta1.element.-psjd-doi-10_2478_BF02476293
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.