Publications (103)46.75 Total impact
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Article: Simultaneous measurement of the neutron capture and fission yields of 233-U
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ABSTRACT: We have measured the neutron capture and fission cross section of 233 U at the neutron time-of-flight facility n TOF at CERN in the energy range from 1 eV to 1 MeV with high accuracy by using a high performance 4π BaF 2 Total Absorption Calorimeter (TAC) as a detection device. The method, based on the TAC energy response study, allowing to disentangle between γ's originating from fission and capture will be presented as well as the first very preliminary results.N. Colonna J. Cox C. Domingo-Pardo International Atomic Energy Agency. ; 1213151623(22):17-18. -
Article: Experimental challenges for the Re/Os clock
Proceedings of the International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos - IX. 25-30 June 2006, CERN. 04/2013; -1:55. -
Article: Neutron capture measurements on the s-process termination isotopes lead and bismuth
04/2013; -1:58. -
Article: Au(n,gamma) - the making of a new standard
Proceedings Of Science. Nuclear Astrophysics - Nuclei in the Cosmos IX. 04/2013; -1:80. -
Article: Neutron beam imaging with an XY-micromegas detector at n TOF at CERN
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ABSTRACT: A micromegas detector with a segmented anode in two orthogonal directions, equipped with a neutron/charged particle converter, was developed by a joint effort at CEA and CERN. This 'XY-micromegas' allows the determination of a neutron beam image on an area of 6 × 6 cm 2 with a spatial resolution of 0.5 mm as a function of neutron time of flight (n TOF). The experimental results collected in three years of operation at the n TOF facility are summarized together with a comparison with simulations performed by means of the FLUKA code. PACS numbers: 29.40.Cs, 29.40.Gx (Some figures may appear in colour only in the online journal)Physica Scripta 09/2012; 150:14004-3. · 1.20 Impact Factor -
Article: Neutron-induced fission cross-section of 233U in the energy range 0.5 < En < 20 MeV
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ABSTRACT: The neutron-induced fission cross-section of 233U has been measured at the CERN n_TOF facility relative to the standard fission cross-section of 235U between 0.5 and 20MeV. The experiment was performed with a fast ionization chamber for the detection of the fission fragments and to discriminate against a \alpha -particles from the natural radioactivity of the samples. The high instantaneous flux and the low background of the n_TOF facility result in data with uncertainties of » \approx 3% , which were found in good agreement with previous experiments. The high quality of the present results allows to improve the evaluation of the 233U (n,f) cross-section and, consequently, the design of energy systems based on the Th/U cycle.European Physical Journal A 05/2012; 47(1):1-7. · 2.19 Impact Factor -
Article: Micromegas at low pressure for beam tracking
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ABSTRACT: New facilities like FAIR at GSI or SPIRAL2 at GANIL, will provide radioactive ion beams at low energies (less than 10 MeV/n). Such beams have generally a large emittance, which requires the use of beam tracking detectors to reconstruct the exact trajectories of the nuclei. To avoid the angular and energy straggling that classical beam tracking detectors would generate in the beam due to their thickness, we propose the use of SED (Secondary Electron Detectors). It consists of a low pressure gaseous detector placed outside the beam coupled to an emissive foil in the beam. Since 2008, different low pressure gaseous detectors (wire chambers and micromegas) have been constructed and tested. The performances achievable at low pressure are similar to or even better than the ones at atmospheric pressure. The fast charge collection leads to excellent timing properties as well as high counting rate capabilities. Several micromegas at low pressure were tested in the laboratory demonstrating a good time resolution, 130±30 ps, which is compatible with the results obtained with wire chambers.Journal of Instrumentation 03/2012; 7(03):C03017. · 1.87 Impact Factor -
Article: Neutron-induced fission cross section of $^245$Cm: New results from data taken at the time-of-flight facility n$_$TOF
Phys. Rev. C. 03/2012; 85(3):034616. -
Article: Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications
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ABSTRACT: 044615-1 0556-2813/2012/85(4)/044615(15) ©2012 American Physical Society C. MASSIMI et al. We have measured the neutron capture cross sections of the stable magnesium isotopes 24,25,26 Mg in the energy range of interest to the s process using the neutron time-of-flight facility n_TOF at CERN. Capture events from a natural metal sample and from samples enriched in 25 Mg and 26 Mg were recorded using the total energy method based on C 6 2 H 6 detectors. Neutron resonance parameters were extracted by a simultaneous resonance shape analysis of the present capture data and existing transmission data on a natural isotopic sample. Maxwellian-averaged capture cross sections for the three isotopes were calculated up to thermal energies of 100 keV and their impact on s-process analyses was investigated. At 30 keV the new values of the stellar cross section for 24 Mg, 25 Mg, and 26 Mg are 3.8±0.2 mb, 4.1±0.6 mb, and 0.14±0.01 mb, respectively.Physical Review C. 01/2012; 04461520(29-04461520). -
Article: Neutron-induced fission cross section measurement of U-233, Am-241 and Am-243 in the energy range 0.5 MeV <= E-n <= 20 MeV at n_TOF at CERN
Physica Scripta 01/2012; T150. · 1.20 Impact Factor -
Article: Neutron-induced fission cross section measurement of U-233, Am-241 and Am-243 in the energy range 0.5 MeV <= E-n <= 20 MeV at n_TOF at CERN
Physica Scripta 01/2012; T150. · 1.20 Impact Factor -
Article: Neutron beam imaging with an XY-micromegas detector at n_TOF at CERN
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ABSTRACT: A micromegas detector with a segmented anode in two orthogonal directions, equipped with aPhysica Scripta 01/2012; 2012(T150):014004. · 1.20 Impact Factor -
Article: AGATA - Advanced Gamma Tracking Array
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ABSTRACT: The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realization of gamma-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly-segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterization of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximize its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer.Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/2011; 668:26. · 1.21 Impact Factor -
Article: 96Zr(n, γ) measurement at the n_TOF facility at CERN
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ABSTRACT: The (n, γ) cross section of 96Zr has been investigated at the CERN n_TOF spallation neutron source. High-resolution time-of-flight measurements using an enriched ZrO2 sample allowed us to analyze 15 resonances below 40 keV with improved accuracy. On average, the capture widths were found to be 25% smaller than reported in earlier experiments. If complemented with the contribution by direct radiative capture, the derived Maxwellian averaged cross sections are consistent with activation data at kT=25 keV. The present results confirm the astrophysical implications for the s-process branching at 95Zr.Phys. Rev. C. 11/2011; 84(5). -
Article: Measurement of the 236U(n,f) cross section from 170 meV to 2 MeV at the CERN n_TOF facility
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ABSTRACT: The neutron-induced fission cross section of 236U was measured at the neutron Time-of-Flight (n_TOF) facility at CERN relative to the standard 235U(n,f) cross section for neutron energies ranging from above thermal to several MeV. The measurement, covering the full range simultaneously, was performed with a fast ionization chamber, taking advantage of the high resolution of the n_TOF spectrometer. The n_TOF results confirm that the first resonance at 5.45 eV is largely overestimated in some nuclear data libraries. The resonance triplet around 1.2 keV was measured with high resolution and resonance parameters were determined with good accuracy. Resonances at high energy have also been observed and characterized and different values for the cross section are provided for the region between 10 keV and the fission threshold. The present work indicates various shortcomings of the current nuclear data libraries in the subthreshold region and provides the basis for an accurate re-evaluation of the 236U(n,f) cross section, which is of great relevance for the development of emerging or innovative nuclear reactor technologies.Phys. Rev. C. 10/2011; 84(4). -
Article: Astrophysics at n_TOF Facility at CERN
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ABSTRACT: The neutron time of flight (n_TOF) facility at CERN is a spallation neutron source with white neutron energy spectrum (from thermal to several GeV), covering the full energy range of interest for nuclear astrophysics, in particular for measurements of the neutron capture cross section required in s-process nucleosynthesis. This contribution presents an overview on the astrophysical program carried on at the n_TOF facility, the main results and their implications.Journal of Physics Conference Series 09/2011; 312(4):042024. -
Article: Micromegas detector developments for MIMAC
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ABSTRACT: The aim of the MIMAC project is to detect non-baryonic Dark Matter with a directional TPC. The recent Micromegas efforts towards building a large size detector will be described, in particular the characterization measurements of a prototype detector of 10 $\times$ 10 cm$^2$ with a 2 dimensional readout plane. Track reconstruction with alpha particles will be shown.09/2011; -
Article: Micromegas detector developments for Dark Matter directional detection with MIMAC
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ABSTRACT: The aim of the MIMAC project is to detect non-baryonic Dark Matter with a directional TPC using a high precision Micromegas readout plane. We will describe in detail the recent developments done with bulk Micromegas detectors as well as the characterisation measurements performed in an Argon(95%)-Isobutane(5%) mixture. Track measurements with alpha particles will be shown.05/2011; -
Article: Neutron-induced fission cross section of natPb and 209Bi from threshold to 1 GeV: An improved parametrization
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ABSTRACT: Neutron-induced fission cross sections for natPb and 209Bi were measured with a white-spectrum neutron source at the CERN Neutron Time-of-Flight (n_TOF) facility. The experiment, using neutrons from threshold up to 1 GeV, provides the first results for these nuclei above 200 MeV. The cross sections were measured relative to 235U and 238U in a dedicated fission chamber with parallel plate avalanche counter detectors. Results are compared with previous experimental data. Upgraded parametrizations of the cross sections are presented, from threshold energy up to 1 GeV. The proposed new sets of fitting parameters improve former results along the whole energy range.Phys. Rev. C. 04/2011; 83(4). -
Article: 197Au(n,γ) cross section in the unresolved resonance region
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ABSTRACT: The cross section of the reaction 197Au(n,γ) was measured with the time-of-flight technique at the n_TOF (neutron time-of-flight) facility in the unresolved resonance region between 5 and 400 keV using a pair of C6D6 (where D denotes 2H) liquid scintillators for the detection of prompt capture γ rays. The results with a total uncertainty of 3.9%–6.7% for a resolution of 20 bins per energy decade show fair agreement with the Evaluated Nuclear Data File Version B-VII.0 (ENDF/B-VII.0), which contains the standard evaluation. The Maxwellian-averaged cross section (MACS) at 30 keV is in excellent agreement with the one according to the ENDF/B-VII.0 evaluation and 4.7% higher than the MACS measured independently by activation technique. Structures in the cross section, which had also been reported earlier, have been interpreted as being due to clusters of resonances.Phys. Rev. C. 03/2011; 83(3).
Top co-authors
Top Journals
Institutions
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2007–200711
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University of Notre Dame
USA
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2012
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International Atomic Energy Agency (IAEA)
- Section of Nuclear Data
Vienna, Vienna, Austria
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2009
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GANIL
Caen, Basse-Normandie, France
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2004
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INFN - Istituto Nazionale di Fisica Nucleare
Legnaro, Veneto, Italy
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