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Study of Photon Strength Function of Actinides: the Case of ^(235)U, ^(238)Np and ^(241)Pu
C. Guerrero,F. Alvarez-Velarde,D. Cano-Ott,T. Martinez,E. Mendoza,D. Villamarin,N. Colonna,M. H. Meaze,S. Marrone,G. Tagliente,R. Terlizzi,F. Belloni,U. Abbondanno,K. Fujii,P. M. Milazzo,C. Moreau,G. 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The decay from excited levels in medium and heavy nuclei can be described in a statisticalapproach by means of Photon Strength Functions and Level Density distributions. The study of electromagnetic cascades following neutron capture based on the use of high eciency detectors has been shown to be well suited for probing the properties of the Photon Strength Function of heavy (high level density) and/or radioactive (high background) nuclei. In this work we have investigated for the first time the validity of the recommended PSF of actinides, in particular ^(235)U, ^(238)Np and ^(241)Pu. Our study includes the search for resonance structures in the PSF below S_n and draws conclusions regarding their existence and their characteristics in terms of energy, width and electromagnetic nature.
S. LERSPALUNGSANTI,A. ALBERS,S. OTT,T. DÜSER 한국자동차공학회 2015 International journal of automotive technology Vol.16 No.1
This article demontrates a systematic approach for human ride comfort objectification. The main objective is to integrate the prediction of the subjective comfort evaluation into the concept phase of product development process. By means of the human sensation model based on the Artificial Neural Networks (ANN), the subjectively sensed convenience of each passenger is estimated. In this paper, two examples of the implementation of the proposed methods are discussed. The first example represents an investigation of comfort-relevant design parameters of the drive train, such as the friction coefficient gradient of the clutch friction pair, the mass of inertia and the damping of the dual mass flywheel. The consequent vibrational properties and the subjective assessments during the start-up situation are predicted. The second example considers the determination of gear rattle tendency of a 5-speed manual transmission. To predict the gear rattle presence and to evaluate the resulted annoying level, the ANN-based models representing the NVH experts are elaborated. As a result, a good correlation of the subjective ratings and the predicted evaluations is attained. Consequently, the proposed method can be effectively applied to compare different gearbox solutions for new product concept. Hence, the development time and costs might be significantly reduced.
Past, Present and Future of the n_TOF Facility at CERN
E. Chiaveri,S. Andriamonje,M. Calviani,V. Vlachoudis,M. Brugger,P. Cennini,F. Cerutti,M. Chin,A. Ferrari,Y. Kadi,E. Lebbos,R. Losito,C. Guerrero,V. Becares,D. Cano-Ott,M. Fernandez-Ordonez,E. Gonzalez 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The n_TOF spallation neutron facility is operating at CERN since 2001. Neutrons are produced with a very wide energy range, from thermal up to 1 GeV and with a very high instantaneous flux (10^5n/cm^2/pulse at 200 m from target) thanks to the high intensity (7 × 10^(12) protons/pulse) and low repetition rate of the Proton Synchrotron (PS) which is delivering protons to a lead spallation target. The experimental area is located at 200 m from the target, resulting in a very good energy resolution and beam quality thanks to the adoption of an optimal collimation system. At the end of 2008 the n_TOF facility has resumed operation after a halt of 3 years due to technical issues. This contribution will outline the main physics results obtained by the facility since its inception in 1999, and show the importance of the measured nuclear data in the field of Nuclear Astrophysics and Nuclear Technology. Then it will present the future perspectives of the facility, aiming mainly in the direction of measuring highly radioactive samples, for which the facility has unique capabilities, with a lower background.
D. Cano-Ott,F. Alvarez-Velarde,E. Gonzalez-Romero,C. Guerrero,T. Martinez,E. Mendoza,D. Villamarin,M. C. Vicente,U. Abbondanno,N. Colonna,M. H. Meaze,S. Marrone,G. Tagliente,R. Terlizzi,F. Belloni,K. 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The successful development of advanced nuclear systems for sustainable energy production and nuclear waste management depends on high quality nuclear data libraries. Recent sensitivity studies and reports [1][2][3] have identified the need for substantially improving the accuracy of neutron cross-section data for minor actinides. The n_TOF collaboration has initiated an ambitious experimental program for the measurement of neutron capture cross sections of minor actinides. Two experimental setups have been constructed for this purpose: a Total Absorption Calorimeter (TAC) [4] for measuring neutron capture cross-sections of low-mass and/or radioactive samples and a set of two low neutron sensitivity C_6D_6 detectors for the less radioactive materials.
Physical properties of giant molecular clouds in the Large Magellanic Cloud
Hughes, A.,Wong, T.,Ott, J.,Muller, E.,Pineda, J. L.,Mizuno, Y.,Bernard, J.-P.,Paradis, D.,Maddison, S.,Reach, W. T.,Staveley-Smith, L.,Kawamura, A.,Meixner, M.,Kim, S.,Onishi, T.,Mizuno, N.,Fukui, Y. Blackwell Publishing Ltd 2010 Monthly notices of the Royal Astronomical Society Vol.406 No.3
<P>ABSTRACT</P><P>The Magellanic Mopra Assessment (MAGMA) is a high angular resolution <SUP>12</SUP>CO (<I>J</I>= 1 → 0) mapping survey of giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud using the Mopra Telescope. Here we report on the basic physical properties of 125 GMCs in the LMC that have been surveyed to date. The observed clouds exhibit scaling relations that are similar to those determined for Galactic GMCs, although LMC clouds have narrower linewidths and lower CO luminosities than Galactic clouds of a similar size. The average mass surface density of the LMC clouds is 50 M<SUB>⊙</SUB> pc<SUP>−2</SUP>, approximately half that of GMCs in the inner Milky Way. We compare the properties of GMCs with and without signs of massive star formation, finding that non-star-forming GMCs have lower peak CO brightness than star-forming GMCs. We compare the properties of GMCs with estimates for local interstellar conditions: specifically, we investigate the H <SMALL>I</SMALL> column density, radiation field, stellar mass surface density and the external pressure. Very few cloud properties demonstrate a clear dependence on the environment; the exceptions are significant positive correlations between (i) the H <SMALL>I</SMALL> column density and the GMC velocity dispersion, (ii) the stellar mass surface density and the average peak CO brightness and (iii) the stellar mass surface density and the CO surface brightness. The molecular mass surface density of GMCs without signs of massive star formation shows no dependence on the local radiation field, which is inconsistent with the photoionization-regulated star formation theory proposed by McKee. We find some evidence that the mass surface density of the MAGMA clouds increases with the interstellar pressure, as proposed by Elmegreen, but the detailed predictions of this model are not fulfilled once estimates for the local radiation field, metallicity and GMC envelope mass are taken into account.</P>
Lee, J.K.,Kim, S.Y.,Ott, R.T.,Kim, J.Y.,Eckert, J.,Lee, M.H. MPR Pub. Services 2016 INTERNATIONAL JOURNAL OF REFRACTORY METALS AND HAR Vol.54 No.-
<P>Nanostructured tungsten composites were fabricated by spark plasma sintering of nanostructured composite powders. The composite powders, which were synthesized by mechanical milling of tungsten and Ni-based alloy powders, are comprised of alternating layers of tungsten and metallic glass several hundred nanometers in size. The mechanical behavior of the nanostructured W composite is similar to pure tungsten, however, in contrast to monolithic pure tungsten, some macroscopic compressive plasticity accompanies the enhanced maximum strength up to 2.4 GPa by introducing reinforcement. We have found that the mechanical properties of the composites strongly depend on the uniformity of the nano-grained tungsten matrix and reinforcement phase distribution. (C) 2015 Elsevier Ltd. All rights reserved.</P>
Coordinated underground measurements of gamma-ray emitting radionuclides for plasma physics research
Tzika, Faidra,Hult, Mikael,Fenyvesi, Andrá,s,Bandac, Iulian,Degering, Detlev,Ianni, Aldo,Laubenstein, Matthias,de Vismes-Ott, Anne,Marissens, Gerd,Stroh, Heiko,Lutter, Guillaume,Son, Soohyun,Hon Elsevier 2017 Applied radiation and isotopes Vol.126 No.-
<P><B>Abstract</B></P> <P>Forty-eight samples made of CaF<SUB>2</SUB>, LiF and YVO<SUB>4</SUB> were placed inside the KSTAR Tokamak and irradiated by neutrons and charged particles from eight plasma pulses. The aim was to provide information for plasma diagnostics. Due to the short pulse durations, the activities induced in the samples were low and therefore measurements were performed in five low-background underground laboratories. Details of the underground measurements, together with data on the quality control amongst the radiometric laboratories, are presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> First activation probe experiment was conducted at KSTAR Tokamak. </LI> <LI> The activated samples were measured with low level gamma-ray spectrometry. </LI> <LI> Five CELLAR underground laboratories participated in the measurement campaign. </LI> <LI> The metrological aspects and the comparability of the measurements are discussed. </LI> <LI> The final aim is to determine the neutrons and charged particles fluxes at KSTAR. </LI> </UL> </P>
Characterization of the New n_TOF Neutron Beam: Fluence, Profile and Resolution
C. Guerrero,V. Becares,D. Cano-Ott,M. Fernandez-Ordonez,E. Gonzalez-Romero,F. Martin-Fuertes,T. Martinez,E. Mendoza,G. Pina,J. Quinones,V. Vlachoudis,M. Calviani,S. Andriamonje,M. Brugger,F. Cerutti,E 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
After a halt of four years, the n_TOF spallation neutron facility at CERN has resumed operation in November 2008 with a new spallation target characterized by an improved safety and engineering design, resulting in a more robust overall performance and efficient cooling. The first measurement during the 2009 run has aimed at the full characterization of the neutron beam. Several detectors, such as calibrated fission chambers, the n\textunderscore TOF Silicon Monitor, a MicroMegas detector with ^(10)B and ^(235)U samples, as well as liquid and solid scintillators have been used in order to characterize the properties of the neutron fluence. The spatial profile of the beam has been studied with a specially designed "X-Y" MicroMegas which provided a 2D image of the beam as a function of neutron energy. Both properties have been compared with simulations performed with the FLUKA code. The characterization of the resolution function is based on results from simulations which have been verified by the study of narrow capture resonances of ^(56)Fe, which were measured as part of a new campaign of (n, γ) measurements on Fe and Ni isotopes.