RESUMO
Samples of materials which will be used in the LHC machine for shielding and construction components were irradiated in the stray radiation field of the CERN-EU high-energy reference field facility. After irradiation, the specific activities induced in the various samples were analysed with a high-precision gamma spectrometer at various cooling times, allowing identification of isotopes with a wide range of half-lives. Furthermore, the irradiation experiment was simulated in detail with the FLUKA Monte Carlo code. A comparison of measured and calculated specific activities shows good agreement, supporting the use of FLUKA for estimating the level of induced activity in the LHC.
Assuntos
Materiais de Construção/análise , Transferência Linear de Energia , Modelos Teóricos , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Radioisótopos/análise , Radiometria/métodos , Benchmarking/métodos , Simulação por Computador , Materiais de Construção/normas , Teste de Materiais/métodos , Teste de Materiais/normas , Método de Monte Carlo , Aceleradores de Partículas/instrumentação , Doses de Radiação , Proteção Radiológica/normas , Radiometria/instrumentação , Radiometria/normas , Reprodutibilidade dos Testes , Espalhamento de Radiação , Sensibilidade e Especificidade , SuíçaRESUMO
A new method to estimate remanent dose rates, to be used with the Monte Carlo code FLUKA, was benchmarked against measurements from an experiment that was performed at the CERN-EU high-energy reference field facility. An extensive collection of samples of different materials were placed downstream of, and laterally to, a copper target, intercepting a positively charged mixed hadron beam with a momentum of 120 GeV c(-1). Emphasis was put on the reduction of uncertainties by taking measures such as careful monitoring of the irradiation parameters, using different instruments to measure dose rates, adopting detailed elemental analyses of the irradiated materials and making detailed simulations of the irradiation experiment. The measured and calculated dose rates are in good agreement.
Assuntos
Materiais de Construção/análise , Transferência Linear de Energia , Modelos Teóricos , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Radioisótopos/análise , Radiometria/métodos , Benchmarking/métodos , Simulação por Computador , Materiais de Construção/normas , Teste de Materiais/métodos , Teste de Materiais/normas , Método de Monte Carlo , Aceleradores de Partículas/instrumentação , Doses de Radiação , Proteção Radiológica/normas , Radiometria/instrumentação , Radiometria/normas , Reprodutibilidade dos Testes , Espalhamento de Radiação , Sensibilidade e Especificidade , SuíçaRESUMO
STAC8 is a significant improvement upon its predecessor PHOTON and is a valuable analytical code for quick and conservative beamline shielding designs for synchrotron radiation (SR) facilities. In order to check the applicability, accuracy and limitations of STAC8, studies were conducted to compare the results of STAC8 with those of PHOTON with calculations using the FLUKA and EGS4 Monte Carlo codes. Doses and spectra for scattered SR in a few beam-target-shield geometries were calculated, with and without photon linear polarisation effects. Areas for expanding the STAC8 capabilities, for example, features of the mirror-reflected lights and double-Compton light calculations and the use of monochromatic light have been identified. Some of these features have been implemented and benchmarked against Monte Carlo calculations. Reasonable agreements were found between the STAC8 and Monte Carlo calculations.
Assuntos
Modelos Estatísticos , Método de Monte Carlo , Proteção Radiológica/métodos , Radiometria/métodos , Software , Síncrotrons/instrumentação , Algoritmos , Simulação por Computador , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Doses de Radiação , Validação de Programas de ComputadorRESUMO
PIP: This study examines the possible link between the existence of a pay-as-you-go social security program and individual procreative behavior. When a public old-age income support system takes the place of within-family support, the theoretical literature preducts that fertility rates will decline since children are no longer perceived as important to the old age security of the parents. The author takes up this theoretical problem and examines it through three different but related issues: optimal capital accumulation, optimal population growth and the role of social institutions affecting efficient intergenerational allocations. Econometric analysis employing a steady state growth model is used. Altruism between generations is studied for effect on the standard model. The model shows that for social optimum the per capita pension is related to the growth rate of the population, therefore, for society as a whole, children are investment goods. However, given the existence of a social security system, it is in each household's best interest to have no children at all. Only a government transfer, a child allowance to parents, changes the model and fertility rates. When modified to account for "caring" the model demonstrates that altruistic behavior between generations is not symmetrical. The study concludes that a pay-as-you-go funded social security system should be supplemented by a system of child allowances or replaced by a fully funded social security system.^ieng