ROBINSON ALVES DOS SANTOS
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Artigo IPEN-doc 23868 Experimental and MCNP studies of paraffin and polyethylene in neutron moderation and BF3 detector efficiency2013 - CARDENAS, JOSE P.N.; MADI FILHO, TUFIC; PETRI, ANNA R.; SANTOS, ROBINSON A. dos; MARTINS, JOAO F.T.; CARVALHO, DIEGO V.S.; ALVARENGA, T.; BELLEZZO, M.; LARANJO, G.; LIMA, M.; OLIVEIRA, P.; PEREIRA, MARIA da C.C.The Nuclear and Energy Research Institute – IPEN, offers post-graduate programs, namely: Nuclear Technology - Applications (TNA), Nuclear Technology - Materials (TNM), Nuclear Technology - Reactors (TNR). The Institute programs mission is to form expert technicians and engineers with a strong knowledge in their discipline to work in the nuclear area. The course: “Theoretical Fundaments and Practices of the Instrumentation used in Nuclear Data Acquisition” covers the use of laboratory nuclear instrumentation and the accomplishment of experiments to obtain nuclear parameters. One of these experiments is object of this work: “Experimental and MCNP Studies of Paraffin and Polyethylene Neutron Moderation and BF3 Detector Efficiency”. Neutrons are uncharged particles and, therefore, cannot be detected by Coulomb interactions. Thus, the detector assembly used must contain some kind of material with high cross section for interaction with neutrons, called converters. A boron trifluoride (BF3) detector was used in this experiment to detect neutron in real time. However, the response of this arrangement varies according to the energy range of incident neutrons. Their efficiency for thermal neutrons is above 90%, but, this result decreases, significantly, for neutrons of energy greater than 0.5 eV. The neutron moderation and, consequently, its energy variation were obtained by interposing different thicknesses of moderator material (Paraffin or Polyethylene) between the source and the detector.Artigo IPEN-doc 23875 Am-Be neutron irradiator used for nuclear instrumentation training2013 - MADI FILHO, TUFIC; CARDENAS, JOSE P.N.; PETRI, ANNA R.; SANTOS, ROBINSON A. dos; MARTINS, JOAO F.T.; CARVALHO, DIEGO V.S.; ALVARENGA, T.; BELLEZZO, M.; LARANJO, G.; LIMA, M.; OLIVEIRA, P.; PEREIRA, MARIA da C.C.A neutron irradiator was assembled at IPEN (Nuclear and Energy Research Institute) facility to perform qualitative-quantitative analysis of materials, using thermal and fast neutrons. In order to determine the 116mIn decay constant, a thermal flux obtained experimentally by Monte Carlo N-Particle Transport Code-MCNP, in a previous work, was used in the nuclear experiment. The activity calculated from the activation parameters was 13.51±0.17 kBq and the activity determined experimentally was 12.51± 0.36 kBq. The decay constant determined by the pulse height analyzer (PHA) measures was 211.4 μ·s-1, and that determined by fitting the data using a Multichannel Scaler (MCS) system was 200.3 ± 1.6 μ·s-1. The half-life of 116mIn found in the literature is 3256.8 s, which corresponds to a decay constant of 212.8 μ·s-1. The present experiment does not intend to establish a new value for the decay constant: it solely aims students’ practical exercises in nuclear properties of elements. This experiment is part of the nuclear experimental course.