115 research outputs found

    Sensitivity of measured fission yields on prompt-neutron corrections

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    The amount of emitted prompt neutrons from the fission fragments increases as a function of excitation energy. Yet it is not fully understood whether the increase in \nu(A) as a function of E_{n} is mass dependent. The share of excitation energies among the fragments is still under debate, but there are reasons to believe that the excess in neutron emission originates only from the heavy fragments, leaving \nu_{light}(A) almost unchanged. In this work we investigated the consequences of a mass-dependent increase in \nu(A) on the final mass and energy distributions. The assumptions on \nu(A) are essential when analysing measurements based on the 2E-technique. This choice showed to be significant on the measured observables. For example, the post-neutron emission mass yield distribution revealed changes up to 10-30%. The outcome of this work pinpoint the urgent need to determine \nu(A) experimentally, and in particular, how \nu(A) changes as a function of incident-neutron energy. Until then, many fission yields in the data libraries could be largely affected, since they were analysed based on another assumption on the neutron emission.Comment: 4 pages, 3 figures, Proc. 2013 International Conference on Nuclear Data for Science & Technology (ND2013), March 4-8, 2013, New York, USA, to be published in Nuclear Data Sheet

    Sprinkler Irrigation Systems and Water Saving, A Case Study from South of Iraq

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    The irrigation systems modernization is a part of water resources management improvement process which requires a decision support system, the core of such system is an automated procedure for simulating the relevant processes governing the system. Simulation models have been used in two phases in this research for two specified areas within Maysan and Wasit provinces in Iraq with an area of 480Ă—250 meters for each province, which have been taken as a case study to redesign and replace the existing open channel network with the new sprinkler irrigation system. The first phase is to find a crop water requirement and irrigation requirements for maize, wheat and barley using CROPWAT 8.0 simulation model, while the second phase includes the irrigation network design using EPANET 2.0 simulation model to perform extended period simulation of hydraulic behavior within pressurized pipe networks, in addition to, the SPAW model which have been used to evaluate soil characteristics. This study has revealed that the designed sprinkler system capacity is 113m3/hr with 5.04 mm/hr precipitation rate. The designed sprinkler system can be used to irrigate different crop types including maize, barley and wheat. Since, the sprinkler system has been designed to meet the maize irrigation water requirements which is the heights requiring water consumer crop the during the summer season, then it has the ability to meet the different winter cereals irrigation requirements. The designed system can be used in the different regions of Iraq generally and southern regions, especially because it has been designed to suit the soil that characterized by moderate, slow infiltration rates in addition to suit areas of relatively high wind speed which affecting the water distribution uniformity and slow infiltration rates of soils

    Ion counting efficiencies at the IGISOL facility

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    At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high precision. Fission fragments from a U target are passing through a Ni foil and entering a gas filled chamber. The collected fragments are guided through a mass separator to a Penning trap where their masses are identified. This simulation work focuses on how different fission fragment properties (mass, charge and energy) affect the stopping efficiency in the gas cell. In addition, different experimental parameters are varied (e. g. U and Ni thickness and He gas pressure) to study their impact on the stopping efficiency. The simulations were performed using the Geant4 package and the SRIM code. The main results suggest a small variation in the stopping efficiency as a function of mass, charge and kinetic energy. It is predicted that heavy fragments are stopped about 9% less efficiently than the light fragments. However it was found that the properties of the U, Ni and the He gas influences this behavior. Hence it could be possible to optimize the efficiency.Comment: 52 pages, 44 figure
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