No abstract available

[en] In this paper bulk sample prompt gamma neutron activation analysis (BSPGNAA) was applied to aqueous sample analysis using a relative method. For elemental analysis of an unknown bulk sample, gamma self-shielding coefficient was required. Gamma self-shielding coefficient of unknown samples was estimated by an experimental method and also by MCNP code calculation. The proposed methodology can be used for the determination of the elemental concentration of unknown aqueous samples by BSPGNAA where knowledge of the gamma self-shielding within the sample volume is required.

[en] In this paper, we attempt to determine the self-attenuation correction factor for 37 different sand samples collected from Antalya region of Turkey with densities changing from 2.205 to 2.679 g cm^-3.Transmission method has been used in order to obtain self-attenuation correction factor in comparison with the air and ultrapure water samples for each case. Self-attenuation correction factor versus energy fit curve is obtained. While the self-attenuation correction factor has large values at low energies, it becomes smaller at high energies and tends to become constant thereafter. (author)

No abstract available

[en] We propose a simple theoretical model for star formation in which the local star formation rate (SFR) in a galaxy is determined by three factors. First, the interplay between the interstellar radiation field and molecular self-shielding determines what fraction of the gas is in molecular form and thus eligible to form stars. Second, internal feedback determines the properties of the molecular clouds that form, which are nearly independent of galaxy properties until the galactic interstellar medium (ISM) pressure becomes comparable to the internal giant molecular cloud (GMC) pressure. Above this limit, galactic ISM pressure determines molecular gas properties. Third, the turbulence driven by feedback processes in GMCs makes star formation slow, allowing a small fraction of the gas to be converted to stars per free-fall time within the molecular clouds. We combine analytic estimates for each of these steps to formulate a single star formation law, and show that the predicted correlation between SFR, metallicity, and surface densities of atomic, molecular, and total gas agree well with observations.

No abstract available

[en] This report describes HOW to calculate self-shielding in the unresolved resonance region (URR), in terms of the computer codes we provide to allow a user to do these calculations himself. Here we only describe HOW to calculate; a longer companion report describes in detail WHY it is necessary to include URR self-shielding.

No abstract available

[en] Analytical techniques have been utilized to obtain the radiation attenuation of nuclear power sources. This calculation was extended to cylindrical source geometry and results were computed by means of a computer program. The self-attenuation parameter of an annular fuel source is evaluated by analytical technique. The self-shielding parameter of a solid cylindrical source when the inner radius is allowed to approach zero is evaluated

[en] The paper first introduces two self-shielding models available in the APOLLO2 code: the Sanchez-Coste and the subgroup methods, the former being used for production assembly calculations. These two methods are based on mathematical and physical probability tables, respectively. A comparison study was undertaken to investigate the accuracy of these two approaches on the Rowlands pin-cell benchmark. Results indicate that both techniques lead to results consistent with Monte-Carlo reference calculations. (author)