[en] The dependence of the diffusion parameters including slowing down area, neutron diffusion length and migration length on the voided volume fraction in water has been studied experimentally. For this purpose, the PIEAS Neutron Transport Facility (PNTF) comprised of a 10 Ci Am-Be neutron source and a water filled aluminum tank with Perspex voided tubes has been designed and fabricated. A BF₃ detector was used for the neutron counting. The slowing down area was determined at the cadmium cutoff level. The diffusion parameters were determined first in the absence of voids. The experimentally measured values of the slowing down area, the diffusion length and the migration length have been found in good agreement with the corresponding values determined by other workers. By varying void volume fraction from 0% to 7.5%, the experimental measurements show a monotonic increase in the slowing down area from 58.71±2.6 to 71.28±3.2 cm², in the diffusion length from 2.95±0.13 to 3.11±0.13 cm and in the migration length from 8.21±0.165 to 8.99±0.169 cm. Our measurements show that the diffusion parameters exhibit a quadratic dependence on the void volume fraction

[en] Short communication

[en] It has been proposed that the incorporation of an observer independent minimal length scale into the quantum field theories of the standard model effectively describes phenomenological aspects of quantum gravity. The aim of this paper is to interpret this description and its implications for scattering processes

[en] A unified differential reactor equation is analyzed. Migration is described in the diffusion approximation, slowing-down - in approximation of a heavy single-atom gas. The slowing-down time is shown not to be separated from the total neutron lifetime in a reactor. Thermalization corrections to slowing-down and diffusion lengths are obtained. For a reactor without reflector the criticality equation is written, wherein the probability of escape leakage is not broken down to multipliers depending on the slowing-down and thermalization region parameters

No abstract available

[en] Calculation of the effective diffusion coefficient is proposed using an analytical model based on Nernst-Planck equation, on electroneutrality and on measurements of current intensity. To validate this approach, migration tests were carried out on different w/c mortar samples. In steady state, the resulting effective diffusion coefficients are larger than those usually obtained with models based on Nernst-Planck equation without electroneutrality. An explanation of these differences and the importance of electroneutrality are discussed in the present work

[en] We give bounds for the fluctuations of estimators of the mean entropy production in Gibbsian sources. These bounds are valid for every n, where n denotes the size-length of the sample. We consider two estimators which are based on waiting and hitting times. (paper)

[en] The structure is investigated of the Baer ideal of a finitely generated algebra of arbitrary finite signature over an arbitrary field or over a Noetherian commutative-associative ring satisfying a system of Capelli identities of order n + 1. It is proved that the length of the Baer chain of ideals in such an algebra is at most n. It is proved that the quotient of this algebra modulo the largest nilpotent ideal is representable

[en] We discuss the length at which boundaries affect the magnetization of the quantum Ising chain with free ends. For this purpose we introduce two characteristic length scales describing the size of the boundary-modified region in respectively, longitudinal and transverse magnetization. We show that their finite-size scaling behaviour encodes the position of the critical point and the universal scaling exponent ν. The behaviour of proposed lengths in small systems is also discussed. These results should be useful in the context of both numerical and experimental studies. (paper)

No abstract available