Search

SABRE (Sodium-iodide with Active Background REjection) is a direct dark matter search experiment based on an array of radio-pure NaI(Tl) crystals surrounded by a liquid scintillator veto. Twin SABRE experiments in the Northern and Southern Hemispheres will differentiate a dark matter signal from seasonal and local effects. The experiment is currently in a Proof-of-Principle (PoP) phase, whose goal is to demonstrate that the background rate is low enough to carry out an independent search for a dark matter signal, with sufficient sensitivity to confirm or refute the DAMA result during the following full-scale experimental phase. The impact of background radiation from the detector materials and the experimental site needs to be carefully investigated, including both intrinsic and cosmogenically activated radioactivity. Based on the best knowledge of the most relevant sources of background, we have performed a detailed Monte Carlo study evaluating the expected background in the dark matter search spectral region. The simulation model described in this paper guides the design of the full-scale experiment and will be fundamental for the interpretation of the measured background and hence for the extraction of a possible dark matter signal., Comment: 13 pages, 5 figures

International audience; We discover new, hitherto unknown, shadow poles in Brune's alternative parametrization of R-matrix theory [Brune, Phys. Rev. C 66, 044611 (2002)PRVCAN0556-281310.1103/PhysRevC.66.044611]. Where these poles are, and how many there are, depends on how one continues R-matrix operators to complex wave numbers (especially the shift S and penetration P functions). This has little consequence for the exact R-matrix formalism (past the last energy threshold), as we show one can still always fully reconstruct the scattering matrix with only the previously known alternative parameters (poles and corresponding resonance widths), for which there were as many poles as the number of levels Nλ. However, we generalize the alternative parametrization to the Reich-Moore formalism and show that the choice of continuation is now critical as it changes the alternative parameters values (poles and residue widths are now complex). In order to establish nuclear libraries with alternative parameters, the nuclear community will thus have to decide what convention to adopt. We argue in favor of analytical continuation (against the legacy of Lane and Thomas approach) in the second article [P. Ducru, B. Forget, V. Sobes, G. Hale, and M. Paris, Phys. Rev. C 103, 064609 (2021)10.1103/PhysRevC.103.064609] of this trilogy on pole parametrizations of R-matrix theory, on which we build to establish the windowed multipole representation or R-matrix cross sections in the third and last article [P. Ducru, A. Alhajri, I. Meyer, B. Forget, V. Sobes, C. Josey, and J. Liang, Phys. Rev. C 103, 064610 (2021)10.1103/PhysRevC.103.064610]. We observe the first evidence of shadow poles in the alternative parametrization of R-matrix theory in the isotope Xe134 spin-parity group Jπ=1/2(−) and show how they indeed depend on the choice of continuation to complex wave numbers.

In this follow-up article to [Shadow poles in the alternative parametrization of R-matrix theory, Ducru (2020)], we establish new results on scattering matrix pole expansions for complex wavenumbers in R-matrix theory. In the past, two branches of theoretical formalisms emerged to describe the scattering matrix in nuclear physics: R-matrix theory, and pole expansions. The two have been quite isolated from one another. Recently, our study of Brune's alternative parametrization of R-matrix theory has shown the need to extend the scattering matrix (and the underlying R-matrix operators) to complex wavenumbers. Two competing ways of doing so have emerged from a historical ambiguity in the definitions of the shift $\boldsymbol{S}$ and penetration $\boldsymbol{P}$ functions: the legacy Lane \& Thomas "force closure" approach, versus analytic continuation (which is the standard in mathematical physics). The R-matrix community has not yet come to a consensus as to which to adopt for evaluations in standard nuclear data libraries, such as ENDF. In this article, we argue in favor of analytic continuation of R-matrix operators. We bridge R-matrix theory with the Humblet-Rosenfeld pole expansions, and unveil new properties of the Siegert-Humblet radioactive poles and widths, including their invariance properties to changes in channel radii $a_c$. We then show that analytic continuation of R-matrix operators preserves important physical and mathematical properties of the scattering matrix -- cancelling spurious poles and guaranteeing generalized unitarity -- while still being able to close channels below thresholds., Under review in Phys. Rev. C. 23 pages, 1 figure, 1 table. arXiv admin note: substantial text overlap with arXiv:1903.02661

We investigate the stability, with respect to spatial inhomogeneity, of a two-dimensional dense neutrino gas. The system exhibits growth of seed inhomogeneity due to nonlinear coherent neutrino self-interactions. In the absence of incoherent collisional effects, we observe a dependence of this instability growth rate on the neutrino mass spectrum: the normal neutrino mass hierarchy exhibits spatial instability over a larger range of neutrino number density compared to that of the inverted case. We further consider the effect of elastic incoherent collisions of the neutrinos with a static background of heavy, nucleon-like scatterers. At small scales, the growth of flavor instability can be suppressed by collisions. At large length scales we find, perhaps surprisingly, that for inverted neutrino mass hierarchy incoherent collisions fail to suppress flavor instabilities, independent of the coupling strength., 10 pages, 6 figures Version accepted in PLB. Minor changes. Title changed

A corrected description of the interpolation scheme for the neutron data standards is given. It is emphasized that the energies (nodes) listed are where the evaluated cross sections are shown. A numerical example that shows how the high-resolution 235U(n,f) data should be averaged to be compared with lower resolution cross sections is given.

The exclusive reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ was studied in the photon energy range 3.0--3.8 GeV and the momentum transfer range $0.4l\ensuremath{-}tl1.0\text{ }\text{ }{\mathrm{GeV}}^{2}$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range, the integrated luminosity was about $20\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. The reaction was isolated by detecting the ${\ensuremath{\pi}}^{+}$ and proton in CLAS, and reconstructing the ${\ensuremath{\pi}}^{\ensuremath{-}}$ via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the $S$, $P$, and $D$-waves, in the ${M}_{{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}}$ mass range 0.4--1.4 GeV, were derived performing a partial wave expansion of the extracted moments. Beside the dominant contribution of the $\ensuremath{\rho}(770)$ meson in the $P$-wave, evidence for the ${f}_{0}(980)$ and the ${f}_{2}(1270)$ mesons was found in the $S$ and $D$-waves, respectively. The differential production cross sections $d\ensuremath{\sigma}/dt$ for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the ${f}_{0}(980)$ has been measured in a photoproduction experiment.

Full calculations of six-nucleon reactions with a three-body final state have been elusive and a long-standing issue. We present neutron spectra from the T(t,2n)α (TT) reaction measured in inertial confinement fusion experiments at the OMEGA laser facility at ion temperatures from 4 to 18 keV, corresponding to center-of-mass energies (E_{c.m.}) from 16 to 50 keV. A clear difference in the shape of the TT-neutron spectrum is observed between the two E_{c.m.}, with the ^{5}He ground state resonant peak at 8.6 MeV being significantly stronger at the higher than at the lower energy. The data provide the first conclusive evidence of a variant TT-neutron spectrum in this E_{c.m.} range. In contrast to earlier available data, this indicates a reaction mechanism that must involve resonances and/or higher angular momenta than L=0. This finding provides an important experimental constraint on theoretical efforts that explore this and complementary six-nucleon systems, such as the solar ^{3}He(^{3}He,2p)α reaction.

Full calculations of six-nucleon reactions with a three-body final state have been elusive and a long-standing issue. We present neutron spectra from the T(t,2n)α (TT) reaction measured in inertial confinement fusion experiments at the OMEGA laser facility at ion temperatures from 4 to 18 keV, corresponding to center-of-mass energies (E_{c.m.}) from 16 to 50 keV. A clear difference in the shape of the TT-neutron spectrum is observed between the two E_{c.m.}, with the ^{5}He ground state resonant peak at 8.6 MeV being significantly stronger at the higher than at the lower energy. The data provide the first conclusive evidence of a variant TT-neutron spectrum in this E_{c.m.} range. In contrast to earlier available data, this indicates a reaction mechanism that must involve resonances and/or higher angular momenta than L=0. This finding provides an important experimental constraint on theoretical efforts that explore this and complementary six-nucleon systems, such as the solar ^{3}He(^{3}He,2p)α reaction.

With the need for improving existing nuclear data evaluations, (e.g., ENDF/B-VIII.0 and JEFF-3.3 releases) the first step was to evaluate the standards for use in such a library. This new standards evaluation made use of improved experimental data and some developments in the methodology of analysis and evaluation. In addition to the work on the traditional standards, this work produced the extension of some energy ranges and includes new reactions that are called reference cross sections. Since the effort extends beyond the traditional standards, it is called the neutron data standards evaluation. This international effort has produced new evaluations of the following cross section standards: the H(n,n), Li-6(n,t), B-10(n, alpha), B-10(n,alpha(1)gamma), C-nat(n,n), Au(n,gamma), U-235(n,f) and U-238(n,f). Also in the evaluation process the U-238(n,gamma) and Pu-239(n,f) cross sections that are not standards were evaluated. Evaluations were also obtained for data that are not traditional standards: the Maxwellian spectrum averaged cross section for the Au(n,gamma) cross section at 30 keV; reference cross sections for prompt gamma-ray production in fast neutron-induced reactions; reference cross sections for very high energy fission cross sections; the Cf-252 spontaneous fission neutron spectrum and the U-235 prompt fission neutron spectrum induced by thermal incident neutrons; and the thermal neutron constants. The data and covariance matrices of the uncertainties were obtained directly from the evaluation procedure. Correction in: Nuclear Data Sheets, Volume 163, January 2020, Pages 280-281, DOI:10.1016/j.nds.2019.12.008

We describe the new ENDF/B-VIII.0 evaluated nuclear reaction data library. ENDF/B-VIII.0 fully incorporates the new IAEA standards, includes improved thermal neutron scattering data and uses new evaluated data from the CIELO project for neutron reactions on 1H, 16O, 56Fe, 235U, 238U and 239Pu described in companion papers in the present issue of Nuclear Data Sheets. The evaluations benefit from recent experimental data obtained in the U.S. and Europe, and improvements in theory and simulation. Notable advances include updated evaluated data for light nuclei, structural materials, actinides, fission energy release, prompt fission neutron and γ-ray spectra, thermal neutron scattering data, and charged-particle reactions. Integral validation testing is shown for a wide range of criticality, reaction rate, and neutron transmission benchmarks. In general, integral validation performance of the library is improved relative to the previous ENDF/B-VII.1 library. Fil: Brown, D.A.. Brookhaven National Laboratory; Estados Unidos Fil: Chadwick, M.B.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Capote, R.. International Atomic Energy Agency, Vienna; Austria Fil: Kahler, A.C.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Trkov, A.. International Atomic Energy Agency, Vienna; Austria Fil: Herman, M.W.. Brookhaven National Laboratory; Estados Unidos Fil: Sonzogni, A.A.. Brookhaven National Laboratory; Estados Unidos Fil: Danon, Y.. Rensselaer Polytechnic Institute; Estados Unidos Fil: Carlson, A.D.. National Institute of Standards and Technology; Estados Unidos Fil: Dunn, M.. Spectra Tech; Estados Unidos Fil: Smith, D.L.. Argonne National Laboratory; Estados Unidos Fil: Hale, G.M.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Arbanas, G.. Oak Ridge National Laboratory; Estados Unidos Fil: Arcilla, R.. Brookhaven National Laboratory; Estados Unidos Fil: Bates, C.R.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Beck, B.. Lawrence Livermore National Laboratory; Fil: Becker, B.. Gesellschaft für Anlagen und Reaktorsicherheit; Alemania Fil: Brown, F.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Casperson, R.J.. Lawrence Livermore National Laboratory; Estados Unidos Fil: Conlin, J.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Cullen, D.E.. Lawrence Livermore National Laboratory; Estados Unidos Fil: Descalle, M.A.. Lawrence Livermore National Laboratory; Estados Unidos Fil: Firestone, R.. Lawrence Berkeley National Laboratory; Estados Unidos Fil: Gaines, T.. AWE plc; Reino Unido Fil: Guber, K.H.. Oak Ridge National Laboratory; Estados Unidos Fil: Hawari, A.I.. University of North Carolina; Estados Unidos Fil: Holmes, J.. Naval Nuclear Laboratory; Estados Unidos Fil: Johnson, T.D.. Brookhaven National Laboratory; Estados Unidos Fil: Kawano, T.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Kiedrowski, B.C.. University of Michigan; Estados Unidos Fil: Koning, A.J.. International Atomic Energy Agency, Vienna; Austria Fil: Kopecky, S.. EC-JRC; Bélgica Fil: Leal, L.. Institut de Radioprotection et de Sûreté Nucléaire; Francia Fil: Lestone, J.P.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Lubitz, C.. Naval Nuclear Laboratory; Estados Unidos Fil: Marquez Damian, Jose Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Mattoon, C.M.. Lawrence Livermore National Laboratory; Estados Unidos Fil: McCutchan, E.A.. Brookhaven National Laboratory; Estados Unidos Fil: Mughabghab, S.. Brookhaven National Laboratory; Estados Unidos Fil: Navratil, P.. TRIUMF; Canadá Fil: Neudecker, D.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Nobre, G.P.A.. Brookhaven National Laboratory; Estados Unidos Fil: Noguere, G.. Commissariat A Energie Atomique; Francia Fil: Paris, M.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Pigni, M.T.. Oak Ridge National Laboratory; Estados Unidos Fil: Plompen, A.J.. EC-JRC; Bélgica Fil: Pritychenko, B.. Brookhaven National Laboratory; Estados Unidos Fil: Pronyaev, V.G.. PI Atomstandart at SC Rosatom; Rusia Fil: Roubtsov, D.. Laboratoires Nucleaires Canadiens; Canadá Fil: Rochman, D.. Paul Scherrer Institut; Suiza Fil: Romano, P.. Argonne National Laboratory; Estados Unidos Fil: Schillebeeckx, P.. EC-JRC; Bélgica Fil: Simakov, S.. Karlsruhe Institute of Technology; Alemania Fil: Sin, M.. University of Bucharest; Rumania Fil: Sirakov, I.. Institute For Nuclear Research And Nuclear Energy Bulgarian Academy Of Sciences; Bulgaria Fil: Sleaford, B.. Lawrence Livermore National Laboratory; Estados Unidos Fil: Sobes, V.. Oak Ridge National Laboratory; Estados Unidos Fil: Soukhovitskii, E.S.. Joint Institute for Energy and Nuclear Research; Bielorrusia Fil: Stetcu, I.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Talou, P.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos. Oak Ridge National Laboratory; Estados Unidos Fil: Thompson, I.. Lawrence Livermore National Laboratory; Estados Unidos Fil: van der Marck, S.. NRG; Países Bajos Fil: Welser-Sherrill, L.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Wiarda, D.. Oak Ridge National Laboratory; Estados Unidos Fil: White, M.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Wormald, J.L.. University of North Carolina; Estados Unidos Fil: Wright, R.Q.. Oak Ridge National Laboratory; Estados Unidos Fil: Zerkle, M.. Naval Nuclear Laboratory; Estados Unidos Fil: Zerovnik, G.. EC-JRC; Bélgica Fil: Zhu, Yan. University of North Carolina; Estados Unidos

Given the increasing availability of new cultivars with high yield potential, the use of annual tropical forages to improve cattle production systems is increasing and therefore warrants more research. The objective of this study was to quantify the influence of feed supplementation and nitrogen fertilization on the diurnal ingestive behaviour of crossbred steers (zebu x taurine), maintained on a pasture of Alexander grass ( Urochloa plantaginea ). The treatments included the application of nitrogen fertilizer at 100 kg/ha; at 100 kg/ha + supplemented feed of wheat bran (0.5% of bodyweight); and at 200 kg/ha. The study used a completely randomized design with three replications. The paddock size was 0.7 ha. Data were analysed by fitting mixed models. The times spent resting, ruminating and consuming water were not different among treatments. However, time spent grazing significantly differed. On average, steers given supplemented feed spent less time grazing (297 min/day) than steers without the supplemented feed (345 min/day). Steers in the pasture with supplementation showed a significantly greater number of daytime bites (2029 bites) than steers in the 200 kg nitrogen treatment (1715 bites). Supplementation reduced grazing time without altering other behaviour variables. The number of daily bites was lower on the pasture with the higher nitrogen level. Keywords: Feeding time, grazing, idle, nitrogen fertilization, rumination

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies - 235,238U, 239Pu, 56Fe, 16O and 1H - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform Fil: Chadwick, M.B.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Capote, R.. International Atomic Energy Agenc; Austria Fil: Trkov, A.. Brookhaven National Laboratory; Estados Unidos Fil: Herman, M.W.. Brookhaven National Laboratory; Estados Unidos Fil: Brown, D.A.. European Commission, Joint Research Center; Bélgica Fil: Hale, G.M.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Kahler, A.C.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Talou, P.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Plompen, A.J.. European Commission, Joint Research Center; Bélgica Fil: Schillebeeckx, P.. European Commission, Joint Research Center; Bélgica Fil: Pigni, M.T.. Oak Ridge National Laboratory; Estados Unidos Fil: Leal, L.. Institut de Radioprotection et de Surete Nucleaire; Francia Fil: Danon, Y.. Rensselaer Polytechnic Institute; Estados Unidos Fil: Carlson, A.D.. National Institute of Standards and Technology; Estados Unidos Fil: Romain, P.. Commissariat a L'Energie Atomique; Francia Fil: Morillon, B.. Commissariat a L'Energie Atomique; Francia Fil: Bauger, E.. Commissariat a L'Energie Atomique; Francia Fil: Hambsch, F.-J.. European Commission, Joint Research Center; Bélgica Fil: Kopecky, S.. European Commission, Joint Research Center; Bélgica Fil: Giorginis, G.. European Commission, Joint Research Center; Bélgica Fil: Kawano, T.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Lestone, J.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Neudecker, D.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Rising, M.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Paris, M.. Los Alamos National High Magnetic Field Laboratory; Estados Unidos Fil: Nobre, G.P.A.. Brookhaven National Laboratory; Estados Unidos Fil: Arcilla, R.. Brookhaven National Laboratory; Estados Unidos Fil: Cabellos, O.. Organisation for Economic Co-operation and Development. Nuclear Energy Agency; Francia Fil: Hill, I.. Organisation for Economic Co-operation and Development. Nuclear Energy Agency; Francia Fil: Dupont, E.. Organisation for Economic Co-operation and Development. Nuclear Energy Agency; Francia Fil: Koning, A.J.. International Atomic Energy Agency; Austria Fil: Cano Ott, D.. Centro de Investigaciones Energéticas Medioambientales y Tecnólogicas; España Fil: Mendoza, E.. Centro de Investigaciones Energéticas Medioambientales y Tecnólogicas; España Fil: Balibrea, J.. Centro de Investigaciones Energéticas Medioambientales y Tecnólogicas; España Fil: Paradela, C.. European Commission. Joint Research Center; Bélgica Fil: Durán, I.. Universidad de Santiago de Compostela; España Fil: Qian, J.. China Nuclear Data Center; China Fil: Ge, Z.. China Nuclear Data Center; China Fil: Liu, T.. China Nuclear Data Center; China Fil: Hanlin, L.. China Institute of Atomic Energy; China Fil: Ruan, X.. China Institute of Atomic Energy; China Fil: Haicheng, W.. China Institute of Atomic Energy; China Fil: Sin, M.. Bucharest University; Rumania Fil: Noguere, G.. Commissariat a L'Energie Atomique. Nuclear Energy Division; Francia Fil: Bernard, D.. Commissariat a L'Energie Atomique. Nuclear Energy Division; Francia Fil: Jacqmin, R.. Commissariat a L'Energie Atomique. Nuclear Energy Division; Francia Fil: Bouland, O.. Commissariat a L'Energie Atomique. Nuclear Energy Division; Francia Fil: De Saint Jean, C.. CEA, Nuclear Energy Division; Francia Fil: Pronyaev, V.G.. PI Atomstandart at SC Rosatom; Rusia Fil: Ignatyuk, A.V.. Institute of Physics and Power Engineering; Rusia Fil: Yokoyama, K.. Japan Atomic Energy Agency; Japón Fil: Ishikawa, M.. Japan Atomic Energy Agency; Japón Fil: Fukahori, T.. Japan Atomic Energy Agency; Japón Fil: Iwamoto, N.. Japan Atomic Energy Agency; Japón Fil: Iwamoto, O.. Japan Atomic Energy Agency; Japón Fil: Kunieda, S.. Japan Atomic Energy Agency; Japón Fil: Lubitz, C.R.. Knolls Atomic Power Laboratory; Estados Unidos Fil: Salvatores, M.. Idaho National Laboratory; Estados Unidos Fil: Palmiotti, G.. Idaho National Laboratory; Estados Unidos Fil: Kodeli, I.. Jozef Stefan Institute; Eslovenia Fil: Kiedrowski, B.. University of Michigan; Estados Unidos Fil: Roubtsov, D.. Canadian Nuclear Laboratories; Canadá Fil: Thompson, I.. Lawrence Livermore National Laboratory; Estados Unidos Fil: Quaglioni, S.. Lawrence Livermore National Laboratory; Estados Unidos Fil: Kim, H.I.. Korean Atomic Energy Research Institute; Corea del Sur Fil: Lee, Y.O.. Korean Atomic Energy Research Institute; Corea del Sur Fil: Fischer, U.. Karlsruhe Institute of Technology; Alemania Fil: Simakov, S.. Karlsruhe Institute of Technology; Alemania Fil: Dunn, M.. Oak Ridge National Laboratory; Estados Unidos Fil: Guber, K.. Oak Ridge National Laboratory; Estados Unidos Fil: Marquez Damian, Jose Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Cantargi, Florencia Olga. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Sirakov, I.. Institute for Nuclear Research and Nuclear Energy; Bulgaria Fil: Otuka, N.. International Atomic Energy Agency; Austria Fil: Daskalakis, A.. Naval Nuclear Laboratory; Estados Unidos Fil: McDermott, B.J.. Naval Nuclear Laboratory; Estados Unidos Fil: van der Marck, S.C.. Nuclear Research and Consultancy Group; Países Bajos

O objetivo do experimento foi avaliar a associação da ervilhaca (Vica sativa) ou da suplementação energética em pastagem de aveia branca (Avena sativa) sobre o desempenho de novilhos de corte na fase de terminação. Foram utilizados 18 novilhos castrados, 1/4 Marchegiana 1/4Aberdeen Angus2/4 Nelore, com peso vivo e idade média de 360kg e 19 meses, respectivamente, divididos em três tratamentos: pastagem de aveia branca, pastagem de aveia branca consorciada com ervilhaca e pastagem de aveia branca com suplementação energética (milho grão triturado, 1% do peso vivo por dia, na matéria seca). O delineamento experimental utilizado foi o de blocos ao acaso com três tratamentos e três repetições. Houve interação significativa entre o período de avaliação e os tratamentos para participação do componente folha da aveia na pastagem. A participação da ervilhaca aumentou no decorrer do experimento de 3,51% para 12,21% consequentemente a participação da aveia diminuiu no decorrer do experimento. Não houve diferença significativa (P>0,05) para massa de forragem, carga animal, oferta de forragem e taxa de acúmulo diário entre os tratamentos. Os animais que receberam suplementação apresentaram maior (P0.05) was found for the forage mass, stoking rate, forage offer and rate of daily accumulation between treatments. The animals that received supplementation showed higher (P

Through the R-matrix analysis, neutron cross sections as well as the covariance are estimated for 16 O in the resolved resonance range. Although we consider the current results are still preliminary, we present the summary of the cross section analysis and the results of data uncertainty/covariance, including those for the differential cross sections. It is found that the values obtained highlight consequences of nature in the theory as well as knowledge from measurements, which gives a realistic quantification of evaluated nuclear data covariances.

After first reviewing the parametric description of light-element reactions in multichannel systems using R-matrix theory and features of the general LANL R-matrix analysis code EDA, we describe how its chi-square minimization procedure gives parameter covariances. This information is used, together with analytically calculated sensitivity derivatives, to obtain cross section covariances for all reactions included in the analysis by first-order error propagation. Examples are given of the covariances obtained for systems with few resonances ( 5 He) and with many resonances ( 13 C ). We discuss the prevalent problem of this method leading to cross section uncertainty estimates that are unreasonably small for large data sets. The answer to this problem appears to be using parameter confidence intervals in place of standard errors.

Few-body nuclear physics often relies upon phenomenological models, with new efforts at the ab initio theory reported recently; both need high-quality benchmark data, particularly at low center-of-mass energies. We use high-energy-density plasmas to measure the proton spectra from ^{3}He+T and ^{3}He+^{3}He fusion. The data disagree with R-matrix predictions constrained by neutron spectra from T+T fusion. We present a new analysis of the ^{3}He+^{3}He proton spectrum; these benchmarked spectral shapes should be used for interpreting low-resolution data, such as solar fusion cross-section measurements.

We calculate Boltzmann neutrino energy transport with self-consistently coupled nuclear reactions through the weak-decoupling-nucleosynthesis epoch in an early universe with significant lepton numbers. We find that the presence of lepton asymmetry enhances processes which give rise to nonthermal neutrino spectral distortions. Our results reveal how asymmetries in energy and entropy density uniquely evolve for different transport processes and neutrino flavors. The enhanced distortions in the neutrino spectra alter the expected big bang nucleosynthesis light element abundance yields relative to those in the standard Fermi-Dirac neutrino distribution cases. These yields, sensitive to the shapes of the neutrino energy spectra, are also sensitive to the phasing of the growth of distortions and entropy flow with time/scale factor. We analyze these issues and speculate on new sensitivity limits of deuterium and helium to lepton number., 19 pages, 14 figures, 5 tables

Evaluations are being done for the H(n,n), 6Li(n,t), 10B(n,αγ), 10B(n,α), C(n,n), Au(n,γ), 235U(n,f) and 238U(n,f) standard cross sections. Evaluations are also being done for data that are not traditional standards including: the Au(n,γ) cross section at energies below where it is considered a standard; reference cross sections for prompt gamma-ray production in fast neutron-induced reactions; reference cross sections for very high energy fission cross sections; the 235U thermal neutron fission spectrum and the 252Cf spontaneous fission neutron spectrum and the thermal constants.

We report the latest results from R-matrix analyses of reactions in the 13,14C and 17O systems that are of interest in reactor applications and nuclear astrophysics. These were done in order to provide separate cross sections for the stable isotopes (12,13C) of natural carbon, and to contribute improved cross sections for 16O to the CIELO project. Although particular attention was paid to the data in the standards region (

We study derivatives of the shift and penetration factors of collision theory with respect to energy, angular momentum, and charge. Definitive results for the signs of these derivatives are found for the repulsive Coulomb case. In particular, we find that the derivative of the shift factor with respect to energy is positive for the repulsive Coulomb case, a long anticipated but heretofore unproven result. These results are closely connected to the properties of the sum of squares of the regular and irregular Coulomb functions; we also present investigations of this quantity., Comment: 13 pages, 1 figure

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies – 16 O, 56 Fe, 235,8 U and 239 Pu – with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

Avaliaram-se os efeitos da suplementação e o uso de cultura de levedura sobre o ganho médio diário (GMD), os parâmetros ruminais e a concentração de ureia plasmática em bezerros sob pastejo de aveia preta (Avena strigosa) e azevém (Lolium multiflorum), e estudaram-se a produção e a composição química da forragem. Utilizaram-se 32 bezerros, em pastejo contínuo e lotação variável. Os tratamentos foram: apenas mistura mineral (MM); mistura mineral mais levedura (MML); mistura mineral mais ração (MMR); e mistura mineral mais ração mais levedura (MMRL). A MM contendo casca de soja foi ofertada em 150g/animal/dia, e a levedura foi adicionada à MM na quantidade de 10g/animal/dia. A ração contendo 75% de NDT e 23% de PB foi fornecida para um consumo diário médio de 12g/kg de peso corporal. O GMD, para os respectivos tratamentos, foi 0,610; 0,599; 0,809 e 0,818kg/animal, na ordem citada. A concentração de amônia ruminal e a de ureia plasmática não foram influenciadas pelos tratamentos. A biomassa forrageira diminuiu ao longo do ciclo vegetativo, com rendimentos inicial e final de 1.364 e 879kg de MS/ha, e os teores médios de NDT e PB de 71,7 e 11,7%, respectivamente. O fornecimento do suplemento melhorou o desempenho dos animais, e a adição de levedura não influenciou as variáveis estudadas. We evaluated the effects of supplementation and use of yeast culture on the average daily gain (ADG), ruminal parameters and plasma urea nitrogen in calves grazing oat (Avena strigosa) and ryegrass (Lolium multiflorum) and studied the production and chemical composition of forage. 32 calves were used in continuous grazing with variable stocking rate. The treatments administered were: only mineral (MM), administration of mineral with yeast (MML), mineral plus ration (MMR) and mineral plus ration with yeast (MMRL). MM added with soybean hulls was supplied at 150 g/animal/day and yeast added to the MM in the amount of 10 g/animal/day. The ration containing 75% of TDN and 23% of PB was supplied for an average daily intake of 12 g /kg of body weight. The ADG for the respective treatments were 0.610, 0.599, 0.809 and 0.818kg/animal, respectively. The concentration of ruminal ammonia and plasma urea was not affected by treatments. Forage biomasses declined throughout the growing season, with initial and final yields of 1.364 and 879kg DM/ha, and TDN and CP levels of 71.7 and 11.7%, respectively. The supply of the supplement improved animal performance, and the addition of yeast did not influence the variables studied.

Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of 6Li in low-metallicity stars. Using high energy-density plasmas we measure the T(3He,γ)6Li reaction rate, a candidate for anomalously high 6Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. In conclusion, this is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.

O objetivo deste estudo foi avaliar o desempenho de bezerros recebendo ou não suplemento energético, mantidos em pastagem de aveia preta (Avena strigosa Schreb) manejada sob duas ofertas de forragem. Foram utilizados 16 animais do grupamento genético Composto Marchangus Z (1/4 Marchigiana 1/4 Angus 1/2 Nelore), com oito meses de idade, castrados, e com peso médio inicial de 200kg. O delineamento experimental utilizado foi o inteiramente ao acaso, em um fatorial 2x2 (duas ofertas de forragem x dois manejos alimentares - com e sem suplementação de milho moído). Não houve interação significativa entre oferta e suplementação para nenhuma das variáveis. A oferta de forragem real ficou próxima do estipulado para 6 e 10% (5,95% e 9,07%, respectivamente). A oferta de 6% apresentou maior porcentagem de folha (57,0 contra 30,4%), menor porcentagem de colmo (43,0 contra 69,6%) e, consequentemente, maior relação folha/colmo (1,45 contra 0,45), resultando em pastagens de melhor qualidade (PB = 20,0 contra 13,6%) na menor oferta. A taxa de acúmulo diária foi maior (P

We discuss how small neutrino rest masses can increase the expansion rate near the photon decoupling epoch in the early universe, causing an earlier, higher temperature freeze-out for ionization equilibrium compared to the massless neutrino case. This yields a larger free-electron fraction. A larger ratio of the sound horizon to the photon diffusion length follows, implying a smaller inferred Neff. This neutrino-mass/recombination effect depends strongly on the neutrino rest masses. Though below current sensitivity, this effect could be probed by next-generation cosmic microwave background experiments, giving an observational handle of neutrino mass physics., Comment: 6 pages, 6 figures; reorganized, content unchanged

The absolute total cross sections for np and pp scattering below 1000 MeV are determined based on partial-wave analyses (PWAs) of nucleon-nucleon scattering data. These cross sections are compared with the most recent ENDF/B-VII.0 and JENDL-3.3 data files, and the Nijmegen PWA. Systematic deviations from the ENDF/B-VII.0 and JENDL-3.3 evaluations are found to exist in the low-energy region. Comparison of the np evaluation with the result of most recent np total and differential cross section measurements will be discussed. Results of those measurements were not used in the evaluation database. A comparison was done to check a quality of evaluation and its capabilities to predict experimental observables. Excellent agreement was found between the new experimental data and our PWA predictions.

We perform a self-consistent calculation of collective neutrino oscillations including the effect of back scattered neutrinos (Halo effect) in the `single-angle' approximation, within a spherically symmetric supernova model. We find that due to the Halo effect the onset of flavor transformations is pushed to smaller radii, by a few kilometers. The celebrated phenomenon of the spectral split is found to be robust under the present inclusion of the Halo effect., Comment: 13 pages, 5 figures

The Web of Science interface counts at most 100,000 retrieved items from a single query. If the query results in a dataset containing more than 100,000 items the number of retrieved items is indicated as >100,000. The problem studied here is how to find the exact number of items in a query that leads to more than 100,000 items. One way to achieve this objective is presented. The retrieval of the entire scientific production from the United States in a specific year (2007) is counted and an advanced search strategy is designed. Different sections of items can be retrieved using the Source field of the database. A Boolean statement was created with the aim of eliminating overlapped sections and improving the accuracy of this search strategy.

This paper presents a partially reusable, two-stage-to-orbit launch vehicle concept for delivering 65 metric ton payloads to low Earth orbit. A winged booster and an expendable core stage each use identical main propulsion, thrust structure, and propellant feed systems. For both stages, four 745,000 lbf thrust, RS-68 oxygen/hydrogen rocket engines, presently used on the Delta-IV launch vehicle, are used. The booster, which does not require reentry thermal protection, ascends to aMach 2.4, 81,000 ft altitude condition, separates from the core stage, and glides back to a runway landing. Sixty-five metric tons in orbit would be enabling to a variety of exploration missions, including very large telescope emplacement missions, robust outer planet missions, and others requiring large payloadmasses or volumes. Use of a reusable booster, designed formaintainability and affordability, would, in combination with an expendable core using common propulsion, allow for significant reductions in recurring costs compared with a totally expendable vehicle with similar payload capabilities.

An $R$-matrix model for three-body final states is presented and applied to a recent measurement of the neutron energy spectrum from the $^{3}\mathrm{H}+^{3}\mathrm{H}\ensuremath{\rightarrow}2n+\ensuremath{\alpha}$ reaction. The calculation includes the $n\ensuremath{\alpha}$ and $nn$ interactions in the final state, angular momentum conservation, antisymmetrization, and the interference between different channels. A good fit to the measured spectrum is obtained, where clear evidence for the ${}^{5}\mathrm{He}$ ground state is observed. The model is also used to predict the $\ensuremath{\alpha}$-particle spectrum from $^{3}\mathrm{H}+^{3}\mathrm{H}$ as well as particle spectra from $^{3}\mathrm{He}+^{3}\mathrm{He}$. The $R$-matrix approach presented here is very general and can be adapted to a wide variety of problems with three-body final states.

We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and cosmic microwave background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy density, helium abundance, deuterium abundance, effective number of neutrinos, and sum of the light neutrino mass eigenstates. We give examples for constraints on dark radiation, neutrino rest mass, lepton numbers, and scenarios for light and heavy sterile neutrinos., 29 pages, 10 figures

The Gamma Reaction History (GRH) diagnostic developed and lead by the Los Alamos National Laboratory GRH Team is used to determine the bang time and burn width of imploded inertial confinement fusion capsules at the National Ignition Facility. The GRH team is conceptualizing and designing a new Gamma-­to-Electron Magnetic Spectrometer (GEMS), that would be capable of an energy resolution ΔE/E~3-­5%. In this whitepaper we examine the physics that could be explored by the combination of these two gamma-ray diagnostics, with an emphasis on the sensitivity needed for measurements. The main areas that we consider are hydrodynamical mixing, ablator areal density and density profile, and temporal variations of the density of the cold fuel and the ablator during the DT burn of the capsule.

This paper describes the development of a platform to study astrophysically relevant nuclear reactions using inertial-confinement fusion implosions on the OMEGA and National Ignition Facility laser facilities, with a particular focus on optimizing the implosions to study charged-particle-producing reactions. Primary requirements on the platform are high yield, for high statistics in the fusion product measurements, combined with low areal density, to allow the charged fusion products to escape. This is optimally achieved with direct-drive exploding pusher implosions using thin-glass-shell capsules. Mitigation strategies to eliminate a possible target sheath potential which would accelerate the emitted ions are discussed. The potential impact of kinetic effects on the implosions is also considered. The platform is initially employed to study the complementary T(t,2n)α, T(3He,np)α and 3He(3He,2p)α reactions. Proof-of-principle results from the first experiments demonstrating the ability to accurately measur...

We introduce a new computational capability that moves toward a self-consistent calculation of neutrino transport and nuclear reactions for big bang nucleosynthesis (BBN). Such a self-consistent approach is needed to be able to extract detailed information about nuclear reactions and physics beyond the standard model from precision cosmological observations of primordial nuclides and the cosmic microwave background radiation. We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our approach allows the dissection of the relative contributions of each process responsible for evolving the dynamics of the early universe. Such an approach allows a detailed account of the evolution of the active neutrino energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and 'ow between the neutrino and photon/electron/positron/baryon plasma components. Our calculations reveal nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions. We discuss the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma. These e↑ects result in changes in the computed values of the BBN deuterium and helium-4 yields that are on the order of a half-percent relative to a baseline standard BBN calculation with no neutrino transport. This is an order of magnitude larger e↑ect than in previous estimates. For particular implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium and a 0.6% decrease in 4 He over our baseline. The magnitude of these changes are on the order of uncertainties in the nuclear physics for the case of deuterium and are potentially signi↓cant for the error budget of helium in upcoming cosmological observations.