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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.
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.
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.
Improved Neutron Capture Cross Section Measurements with the n_TOF Total Absorption Calorimeter
E. Mendoza,V. Becares,A. Casado,D. Cano-Ott,M. Fernandez-Ordonez,E. Gonzalez-Romero,C. Guerrero,T. Martinez,J. J. Vidriales,J. Andrzejewski,J. Marganiec,J. Perkowski,L. Audouin,B. Berthier,L. Tassan-G 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The n_TOF collaboration operates a Total Absorption Calorimeter (TAC) [1] for measuring neutron capture cross-sections of low-mass and/or radioactive samples. The results obtained with the TAC have led to a substantial improvement of the capture cross sections of ^(237)Np and ^(240)Pu [2].The experience acquired during the first measurements has allowed us to optimize the performance of the TAC and to improve the capture signal to background ratio, thus opening the way to more complex and demanding measurements on rare radioactive materials. The new design has been reached by a series of detailed Monte Carlo simulations of complete experiments and dedicated test measurements. The new capture setup will be presented and the main achievements highlighted. KEYWORDS: ND2010, nuclear data, n\textunderscore TOF, background, Monte Carlo, neutron, time of flight, cross section, calorimeter, shielding, simulation, total absorption, gamma ray, neutron capture.
Recent developments in G<small>EANT</small>4
Allison, J.,Amako, K.,Apostolakis, J.,Arce, P.,Asai, M.,Aso, T.,Bagli, E.,Bagulya, A.,Banerjee, S.,Barrand, G.,Beck, B.R.,Bogdanov, A.G.,Brandt, D.,Brown, J.M.C.,Burkhardt, H.,Canal, Ph.,Cano-Ott, D. Elsevier 2016 Nuclear Instruments & Methods in Physics Research. Vol.835 No.-
<P><B>Abstract</B></P> <P>G<SMALL>EANT</SMALL>4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. The adaptation of G<SMALL>EANT</SMALL>4 to multithreading, advances in physics, detector modeling and visualization, extensions to the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Multithreading resulted in a smaller memory footprint and nearly linear speed-up. </LI> <LI> Scoring options, faster geometry primitives, more versatile visualization were added. </LI> <LI> Improved electromagnetic and hadronic models and cross sections were developed. </LI> <LI> Reverse Monte Carlo and general biasing methods were added. </LI> <LI> Physics validation efforts were expanded and new validation tools were added. </LI> </UL> </P>
Monte Carlo Simulations for the Study of a Moderated Neutron Detector
M. B. Gomez Hornillos,V. Gorlychev,R. Caballero,G. Cortes,A. Poch,C. Pretel,F. Calvino,J. L. Tain,A. Algora,J. Agramunt,D. Cano-Ott,T. Martinez,E. Mendoza,J. Rissanen,J. Aysto,A. Jokinen,T. Eronen,I. 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
This work presents the Monte Carlo simulations performed with the MCNPX and GEANT4 codes for the design of a BEta deLayEd Neutron detector, BELEN-20. This detector will be used for the study of beta delayed neutron emission and consists of a block of polyethylene with dimensions 90 × 90 × 80 cm ^3 and 20 cylindrical ^3He gas counters. The results of these simulations have been validated experimentally with a ^(252)Cf source in the laboratory at UPC, Barcelona. Also the first experiment with this detector has been carried out in November 2009 in JYFL, Finland. In this experiment the neutron emission probability after beta decay of the fission products ^(88)Br, ^(94,95)Rb and ^(138)I has been measured; this data is still under analysis. Simulations with MCNPX and GEANT4 have been performed in order to obtain the efficiency of the BELEN-20 detector for each of the above nuclei using the neutron energy distribution corresponding to each nucleus.
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.