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Author (down) Orce, J.N. et al; Rubio, B.
Title Search for two-phonon octupole excitations in Gd-146 Type Journal Article
Year 2016 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A
Volume 52 Issue 6 Pages 166 - 7pp
Keywords
Abstract The low-spin structure of the nearly spherical nucleus Gd-146 was studied using the Sm-144(He-4, 2n) fusion-evaporation reaction. High-statistics gamma-gamma coincidence measurements were performed at iThemba LABS with 7x10(9) gamma-gamma coincidence events recorded. Gated gamma-ray energy spectra show evidence for the 6(2)(+) -> 3(1)(-) -> 0(1)(+) cascade of E3 transitions in agreement with recent findings by Caballero and co-workers, but with a smaller branching ratio of I-gamma = 4.7(10) for the 6(2)(+) -> 3(1)(-) 1905.1 keV gamma ray. Although these findings may support octupole vibrations in spherical nuclei, sophisticated beyond mean-field calculations including angular-momentum projection are required to interpret in an appropriate way the available data due to the failure of the rotational model assumptions in this nucleus.
Address [Orce, J. N.; Raju, M. Kumar; Khumalo, N. A.; Dinoko, T. S.; Easton, J.; Kheswa, N.; Herbert, M. S.; Masiteng, P. L.; Noncolela, S. P.; Shirinda, O.; Sithole, P. S.] Univ Western Cape, Dept Phys, P-B X17, ZA-7535 Bellville, South Africa, Email: jnorce@uwc.ac.za
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6001 ISBN Medium
Area Expedition Conference
Notes WOS:000378999800002 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2750
Permanent link to this record
 
 
Author (down) Olmo, G.J.; Rubiera-Garcia, D.; Sanchez-Puente, A.
Title Classical resolution of black hole singularities via wormholes Type Journal Article
Year 2016 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 76 Issue 3 Pages 143 - 6pp
Keywords
Abstract In certain extensions of General Relativity, wormholes generated by spherically symmetric electric fields can resolve black hole singularities without necessarily removing curvature divergences. This is shown by studying geodesic completeness, the behavior of time-like congruences going through the divergent region, and by means of scattering of waves off the wormhole. This provides an example of the logical independence between curvature divergences and space-time singularities, concepts very often identified with each other in the literature.
Address [Olmo, Gonzalo J.; Sanchez-Puente, A.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: gonzalo.olmo@csic.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000375302500001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2655
Permanent link to this record
 
 
Author (down) Olmo, G.J.; Rubiera-Garcia, D.; Sanchez-Puente, A.
Title Impact of curvature divergences on physical observers in a wormhole space-time with horizons Type Journal Article
Year 2016 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity
Volume 33 Issue 11 Pages 115007 - 12pp
Keywords Singularities; black holes; metric-affine geometry
Abstract The impact of curvature divergences on physical observers in a black hole space-time, which, nonetheless, is geodesically complete is investigated. This space-time is an exact solution of certain extensions of general relativity coupled to Maxwell's electrodynamics and, roughly speaking, consists of two Reissner-Nordstrom (or Schwarzschild or Minkowski) geometries connected by a spherical wormhole near the center. We find that, despite the existence of infinite tidal forces, causal contact is never lost among the elements making up the observer. This suggests that curvature divergences may not be as pathological as traditionally thought.
Address [Olmo, Gonzalo J.; Sanchez-Puente, A.] Univ Valencia, CSIC, Ctr Mixto, Dept Fis Teor, E-46100 Valencia, Spain, Email: gonzalo.olmo@csic.es;
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0264-9381 ISBN Medium
Area Expedition Conference
Notes WOS:000377442000010 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2728
Permanent link to this record
 
 
Author (down) Oliver, J.F.; Rafecas, M.
Title Modelling Random Coincidences in Positron Emission Tomography by Using Singles and Prompts: A Comparison Study Type Journal Article
Year 2016 Publication PLoS One Abbreviated Journal PLoS ONE
Volume 11 Issue 9 Pages e0162096 - 22pp
Keywords
Abstract Random coincidences degrade the image in Positron Emission Tomography, PET. To compensate for their degradation effects, the rate of random coincidences should be estimated. Under certain circumstances, current estimation methods fail to provide accurate results. We propose a novel method, “Singles-Prompts” (SP), that includes the information conveyed by prompt coincidences and models the pile-up. The SP method has the same structure than the well-known “Singles Rate” (SR) approach. Hence, SP can straightforwardly replace SR. In this work, the SP method has been extensively assessed and compared to two conventional methods, SR and the delayed window (DW) method, in a preclinical PET scenario using Monte-Carlo simulations. SP offers accurate estimates for the randoms rates, while SR and DW tend to overestimate the rates (similar to 10%, and 5%, respectively). With pile-up, the SP method is more robust than SR (but less than DW). At the image level, the contrast is overestimated in SR-corrected images, + 16%, while SP produces the correct value. Spill-over is slightly reduced using SP instead of SR. The DW images values are similar to those of SP except for low-statistic scenarios, where DW behaves as if randoms were not compensated for. In particular, the contrast is reduced, -16%. In general, the better estimations of SP translate into better image quality.
Address [Oliver, Josep F.; Rafecas, M.] Inst Fis Corpuscular IFIC UV CSIC, Valencia, Spain, Email: josep.f.oliver@uv.es
Corporate Author Thesis
Publisher Public Library Science Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-6203 ISBN Medium
Area Expedition Conference
Notes WOS:000383255200040 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2825
Permanent link to this record
 
 
Author (down) n_TOF Collaboration (Zugec, P. et al); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L.
Title Integral measurement of the C-12(n, p)B-12 reaction up to 10 GeV Type Journal Article
Year 2016 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A
Volume 52 Issue 4 Pages 101 - 13pp
Keywords
Abstract The integral measurement of the C-12(n, p)B-12 reaction was performed at the neutron time-of-flight facility nTOF at CERN. The total number of B-12 nuclei produced per neutron pulse of the nTOF beam was determined using the activation technique in combination with a time-of-flight technique. The cross section is integrated over the n_TOF neutron energy spectrum from reaction threshold at 13.6 MeV to 10 GeV. Having been measured up to 1 GeV on basis of the U-235(n, f) reaction, the neutron energy spectrum above 200 MeV has been re-evaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The experimental results related to the C-12(n, p)B-12 reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which mostly underestimate the B-12 production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters.
Address [Zugec, P.; Bosnar, D.] Univ Zagreb, Fac Sci, Dept Phys, Zagreb 41000, Croatia, Email: pzugec@phy.hr
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6001 ISBN Medium
Area Expedition Conference
Notes WOS:000376181400001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2683
Permanent link to this record
 
 
Author (down) n_TOF Collaboration (Gunsing, F. et al); Domingo-Pardo, C.; Tain, J.L.; Tarifeño-Saldivia, A.
Title Nuclear data activities at the n_TOF facility at CERN Type Journal Article
Year 2016 Publication European Physical Journal Plus Abbreviated Journal Eur. Phys. J. Plus
Volume 131 Issue 10 Pages 371 - 13pp
Keywords
Abstract Nuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. Experimental nuclear reaction data are compiled on a worldwide basis by the international network of Nuclear Reaction Data Centres (NRDC) in the EXFOR database. The EXFOR database forms an important link between nuclear data measurements and the evaluated data libraries. CERN's neutron time-of-flight facility nTOF has produced a considerable amount of experimental data since it has become fully operational with the start of the scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at CERN's neutron time-of-flight facility nTOF will be presented.
Address [Gunsing, F.; Belloni, F.; Berthoumieux, E.; Diakaki, M.; Dupont, E.] CEA Saclay, Irfu, Gif Sur Yvette, France, Email: gunsing@cea.fr
Corporate Author Thesis
Publisher Springer Heidelberg Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-5444 ISBN Medium
Area Expedition Conference
Notes WOS:000386722000001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2850
Permanent link to this record
 
 
Author (down) n_TOF Collaboration (Diakaki, M. et al); Domingo-Pardo, C.; Tain, J.L.
Title Neutron-induced fission cross section of Np-237 in the keV to MeV range at the CERN n_TOF facility Type Journal Article
Year 2016 Publication Physical Review C Abbreviated Journal Phys. Rev. C
Volume 93 Issue 3 Pages 034614 - 12pp
Keywords
Abstract The neutron-induced fission cross section of Np-237 was experimentally determined at the high-resolution and high-intensity facility n_TOF, at CERN, in the energy range 100 keV to 9 MeV, using the U-235(n, f) and U-238(n, f) cross section standards below and above 2 MeV, respectively. A fast ionization chamber was used in order to detect the fission fragments from the reactions and the targets were characterized as far as their mass and homogeneity are concerned by means of a spectroscopy and Rutherford backscattering spectroscopy respectively. Theoretical calculations within the Hauser-Feshbach formalism have been performed, employing the EMPIRE code, and the model parameters were tuned in order to successfully reproduce the experimental fission cross-sectional data and simultaneously all the competing reaction channels.
Address [Diakaki, M.; Aerts, G.; Andriamonje, S.; Berthoumieux, E.] CEA Saclay, DSM, F-91191 Gif Sur Yvette, France, Email: maria.diakaki@cea.fr
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9985 ISBN Medium
Area Expedition Conference
Notes WOS:000372415600004 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2591
Permanent link to this record
 
 
Author (down) n_TOF Collaboration (Cosentino, L. et al); Domingo-Pardo, C.; Tain, J.L.; Tarifeño-Saldivia, A.
Title Experimental setup and procedure for the measurement of the Be-7(n,alpha)alpha reaction at n_TOF Type Journal Article
Year 2016 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A
Volume 830 Issue Pages 197-205
Keywords Cosmological lithium problem; Big bang nucleosynthesis; Be-7(n,alpha)alpha reaction; n_TOF spallation neutron source
Abstract The newly built second experimental area EAR2 of then n_ToF spallation neutron source at CERN allows to perform (n, charged particles) experiments on short-lived highly radioactive targets. This paper describes a detection apparatus and the experimental procedure for the determination of the cross-section of the Be-7(n,alpha)alpha reaction, which represents one of the focal points toward the solution of the cosmological Lithium abundance problem, and whose only measurement, at thermal energy, dates back to 1963. The apparently unsurmountable experimental difficulties stemming from the huge Be-7 gamma-activity, along with the lack of a suitable neutron beam facility, had so far prevented further measurements. The detection system is subject to considerable radiation damage, but is capable of disentangling the rare reaction signals from the very high background. This newly developed setup could likely be useful also to study other challenging reactions requiring the detectors to be installed directly in the neutron beam.
Address [Cosentino, L.; Musumarra, A.; Pappalardo, A.; Piscopo, M.; Finocchiaro, P.; Cardella, R.; Heyse, J.; Jenkins, D. G.; Kaeppeler, F.; Katabuchi, T.; Kokkoris, M.; Lederer, C.; Lonsdale, S.; Massimi, C.; Mastinu, P.; Matteucci, F.; Mazzone, A.; Milazzo, P. M.; Nolte, R.; Patronis, N.; Pavlik, A.; Rauscher, T.; Schillebeeckx, P.; Stamatopoulos, A.; Tsinganis, A.; Vannini, G.; Vlastou, R.; Wallner, A.; Woods, P. J.] INFN Lab Nazl Sud, Catania, Italy, Email: FINOCCHIARO@LNS.INFN.IT
Corporate Author Thesis
Publisher Elsevier Science Bv Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0168-9002 ISBN Medium
Area Expedition Conference
Notes WOS:000381530300027 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2792
Permanent link to this record
 
 
Author (down) n_TOF Collaboration (Barbagallo, M. et al); Domingo-Pardo, C.; Tain, J.L.; Tarifeño-Saldivia, A.
Title Be-7(n,alpha)He-4 Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN Type Journal Article
Year 2016 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.
Volume 117 Issue 15 Pages 152701 - 7pp
Keywords
Abstract The energy-dependent cross section of the (7)Bed(n,alpha)He-4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be-7 and by the low reaction cross section have been overcome at nTOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the nTOF facility at CERN, the availability of a sufficient amount of chemically pure Be-7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be-7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.
Address [Barbagallo, M.; Colonna, N.; Damone, L.; Mastromarco, M.; Mazzone, A.; Tagliente, G.; Variale, V.] Ist Nazl Fis Nucl, Sez Bari, Bari, Italy, Email: nicola.colonna@ba.infn.it
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Medium
Area Expedition Conference
Notes WOS:000384479300003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2822
Permanent link to this record
 
 
Author (down) NEXT Collaboration (Martin-Albo, J. et al); Muñoz Vidal, J.; Ferrario, P.; Nebot-Guinot, M.; Gomez-Cadenas, J.J.; Alvarez, V.; Carcel, S.; Carrion, J.V.; Cervera-Villanueva, A.; Diaz, J.; Laing, A.; Liubarsky, I.; Lopez-March, N.; Lorca, D.; Martinez, A.; Novella, P.; Palmeiro, P.; Querol, M.; Renner, J.; Rodriguez, J.; Serra, L.; Simon, A.; Sorel, M.; Yahlali, N.
Title Sensitivity of NEXT-100 to neutrinoless double beta decay Type Journal Article
Year 2016 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 05 Issue 5 Pages 159 - 30pp
Keywords Dark Matter and Double Beta Decay (experiments); Rare decay
Abstract NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta (0v beta beta) decay of Xe-136. The detector possesses two features of great value for 0v beta beta searches: energy resolution better than 1% FWHM at the Q value of Xe-136 and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most 4 x 10(-4) counts keV(-1) kg(-1) yr(-1). Accordingly, the detector will reach a sensitivity to the 0v beta beta-decay half-life of 2.8 x 10(25) years (90% CL) for an exposure of 100 kg.year, or 6.0 x 10(25) years after a run of 3 effective years.
Address [Martin-Albo, J.; Munoz Vidal, J.; Ferrario, P.; Nebot-Guinot, M.; Gomez-Cadenas, J. J.; Alvarez, V.; Carcel, S.; Carrion, J. V.; Cervera, A.; Diaz, J.; Laing, A.; Liubarsky, I.; Lopez-March, N.; Lorca, D.; Martinez, A.; Novella, P.; Palmeiro, B.; Querol, M.; Renner, J.; Rodriguez, J.; Serra, L.; Simon, A.; Sorel, M.; Yahlali, N.] CSIC, Inst Fis Corpuscular IFIC, Calle Catedrat Jose Beltran 2, Valencia 46980, Spain, Email: justo.martin-albo@ific.uv.es
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1029-8479 ISBN Medium
Area Expedition Conference
Notes WOS:000391745200003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2928
Permanent link to this record