[en] The number of tallies performed in a given Monte Carlo calculation is limited in most modern Monte Carlo codes by the amount of memory that can be allocated on a single processor. By using domain decomposition, the calculation is now limited by the total amount of memory available on all processors, allowing for significantly more tallies to be performed. However, decomposing the problem geometry introduces significant issues with the way tally statistics are conventionally calculated. In order to deal with the issue of calculating tally variances in domain decomposed environments for the Shift hybrid Monte Carlo code, this paper presents an alternative approach for reactor scenarios in which an assumption is made that once a particle leaves a domain, it does not reenter the domain. Particles that reenter the domain are instead treated as separate independent histories. This assumption introduces a bias that inevitably leads to under-prediction of the calculated variances for tallies within a few mean free paths of the domain boundaries. However, through the use of different decomposition strategies, primarily overlapping domains, the negative effects of such an assumption can be significantly reduced to within reasonable levels.

[en] We consider an evolution transport equation and show that its solution converges to the solution of a diffusion equation, as the mean free path converges to zero. We suppose the medium to be isotropic and consider perfect reflection as boundary conditions

[en] Measurements of the electron transparency of a Micromegas mesh are compared to simulations. The flux conservation argument is shown to lead to inaccurate estimates of the transparency, the importance of accurate geometric modelling of the mesh is discussed and the effect of the dipole moment of the mesh is demonstrated. This study provides a validation of the microscopic simulation methods specifically developed for micropattern devices where the characteristic dimensions are of the same order of magnitude as the electron mean free path in the gas.

[en] In these lectures we describe the bases of angular resolved photoemission: determination of the electronic band structure of solids (bulk), measurements of life-time and mean free path, determination of surfaces states (valence and core) and their relationship with surface reconstruction. (author)

[en] We show that diffusing wave spectroscopy (DWS) is sensitive to the presence of a moderate short-range attraction between droplets in uniform fractionated colloidal emulsions near and below the jamming point associated with monodisperse hard spheres. This moderate interdroplet attraction, induced by micellar depletion, has an energy of about ∼2.4 k _B T, only somewhat larger than thermal energy. Although changes in the mean free path of optical transport caused by this moderate depletion attraction are small, DWS clearly reveals an additional secondary decay-to-plateau in the intensity autocorrelation function at long times that is not present when droplet interactions are nearly hard. We hypothesize that this secondary decay-to-plateau does not reflect the average self-motion of individual droplets experiencing Brownian excitations, but instead results from heterogeneous dynamics involving a sub-population of droplets that still experience bound motion yet with significantly larger displacements than the average. By effectively removing the contribution of this secondary decay-to-plateau, which is linked to greater local heterogeneity in droplet structure caused by the moderate attraction, we obtain self-motion mean square displacements (MSDs) of droplets that reflect only the initial primary decay-to-plateau. Moreover, we show that droplet self-motion primary plateau MSDs can be interpreted using the generalized Stokes-Einstein relation of passive microrheology, yielding quantitative agreement with plateau elastic shear moduli measured mechanically. (paper)

[en] In this paper we analyze an imaging technique based on intensity speckle correlations over incident field position proposed by Newmann and Webb (2014 Phys. Rev. Lett. 113 263903). Its purpose is to reconstruct a field incident on a strongly scattering random medium. The thickness of the complex medium is much larger than the scattering mean free path so that the wave emerging from the random section forms an incoherent speckle pattern. Our analysis clarifies the conditions under which the method can give a good reconstruction and characterizes its performance. The analysis is carried out in the white-noise paraxial regime, which is relevant for the applications in optics that motivated the original paper. (paper)

[en] The method of invariant embedding has been applied to transport calculations for gamma-ray with real cross sections depending upon energy and angle. Some problems including excessive amount of space meshes met in transport calculations for gamma-ray are discussed, followed by the features of the invariant embedding method developed to overcome these difficulties. The method is proved to be practically free from space mesh and can be applied to deep penetration problems. Some results of calculations for exposure buildup factors of gamma-ray up to depths as large as 300 mean free paths are presented. (author)

[en] Photonic crystals are extremely sensitive to structural disorder even to the point of completely losing their functionalities. While, on one side, this can be detrimental for applications in traditional optical devices, on the other side, it gives also rise to very interesting new physics and maybe even new applications. We propose a route to introduce disorder in photonic crystals in a controlled way by creating a certain percentage of vacancies in the lattice. We show how the method works and what type of materials can be obtained this way. Also, we use this system to probe the role of disorder on the resulting transport properties from various points of view, including measurements of the transport and scattering mean free path and the diffusion constant.

[en] Gamma ray linear attenuation coefficients have been measured experimentally for olive bagasse and nutshell by using narrow beam geometry for Co-60 and the values have been compared with soil. These values have been used calculate mean free path, half value layer and tenth value layer parameters. Besides, effect of multi-layered systems (soil + olive bagasse and soil + nutshell) has been analyzed in terms of half value layer

[en] Precise measurement of the neutron lifetime is important in particle physics and cosmology. Along with the Asymmetry parameter, A, the value of the neutron lifetime is important to test the unitarity of the Cabibbo- Kobayashi-Maskawa (CKM) matrix. The neutron lifetime also affects the primordial helium abundance and the calculation of the helium abundance can be used to test cosmological models, like the Big Bang theory. Also, the discrepancy between the most precise value of the neutron lifetime measured using the beam experiment