WorldWideScience

Sample records for intermediate energy fission

  1. Fission in intermediate energy heavy ion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelmy, J.B.; Begemann-Blaich, M.; Blaich, T.; Boissevain, J.; Fowler, M.M.; Gavron, A.; Jacak, B.V.; Lysaght, P.S. (Los Alamos National Lab., NM (USA)); Britt, H.C.; Fields, D.J.; Hansen, L.F.; Lanier, R.G.; Massoletti, D.J.; Namboodiri, M.M.; Remington, B.A.; Sangster, T.C.; Struble, G.L.; Webb, M.L. (Lawrence Livermore National Lab., CA (USA)); Chan, Y.D.; Dacai, A.; Harmon, A.; Leyba, J.; Pouliot, J.; Stokstad, R.G. (Lawrence Berkeley Lab., CA (USA)); Hansen, O.; Levine, M.J.; Thorn, C.E.; Trautmann, W. (Brookhaven National Lab., Upton, NY (USA)); Dichter, B.; Kaufman, S.; Videbaek, F. (Argonne National Lab. (USA)); Fraenkel, Z.; Mamane, G. (Weizmann Inst. of Science, Rehovoth (Israel)); Cebra, D.; Westfall, G.D. (Michigan State Univ., East Lansing (USA))

    1989-10-09

    A systematic study of reaction mechanisms at intermediate energies (50-100 MeV/A) has been performed at the Lawrence Berkeley Laboratory's BeValac using medium weight projectiles on medium and heavy element targets. A gas and plastic phoswich detector system was employed which gave large geometric coverage and a wide dynamic response. The particles identified with the gas detectors could be characterized into three components - intermediate mass fragments (IMF), fission fragments (FF) and heavy residues (HR). Major observed features are: The reaction yields are similar in the 50 to 100 MeV/A range, central collisions have high multiplicty of IMF's with broad angular correlations consistent with a large participant region, effects of final state Coulomb interactions are observed and give information on the size and temporal behavior of the source, true fission yields are dependent on target fissility and correlated with relatively peripheral collisions. Analysis of fission and evaporation yields implies limiting conditions for which fission decay remains a viable deexcitation channel. (orig.).

  2. Fission induced by nucleons at intermediate energies

    CERN Document Server

    Meo, Sergio Lo; Massimi, Cristian; Vannini, Gianni; Ventura, Alberto

    2014-01-01

    Monte Carlo calculations of fission of actinides and pre-actinides induced by protons and neutrons in the energy range from 100 MeV to 1 GeV are carried out by means of a recent version of the Li\\`ege Intranuclear Cascade Model, INCL++, coupled with two different evaporation-fission codes, GEMINI++ and ABLA07. In order to reproduce experimental fission cross sections, model parameters are usually adjusted on available (p,f) cross sections and used to predict (n,f) cross sections for the same isotopes.

  3. Rupturing the hemi-fission intermediate in membrane fission under tension: Reaction coordinates, kinetic pathways, and free-energy barriers.

    Science.gov (United States)

    Zhang, Guojie; Müller, Marcus

    2017-08-14

    Membrane fission is a fundamental process in cells, involved inter alia in endocytosis, intracellular trafficking, and virus infection. Its underlying molecular mechanism, however, is only incompletely understood. Recently, experiments and computer simulation studies have revealed that dynamin-mediated membrane fission is a two-step process that proceeds via a metastable hemi-fission intermediate (or wormlike micelle) formed by dynamin's constriction. Importantly, this hemi-fission intermediate is remarkably metastable, i.e., its subsequent rupture that completes the fission process does not occur spontaneously but requires additional, external effects, e.g., dynamin's (unknown) conformational changes or membrane tension. Using simulations of a coarse-grained, implicit-solvent model of lipid membranes, we investigate the molecular mechanism of rupturing the hemi-fission intermediate, such as its pathway, the concomitant transition states, and barriers, as well as the role of membrane tension. The membrane tension is controlled by the chemical potential of the lipids, and the free-energy landscape as a function of two reaction coordinates is obtained by grand canonical Wang-Landau sampling. Our results show that, in the course of rupturing, the hemi-fission intermediate undergoes a "thinning → local pinching → rupture/fission" pathway, with a bottle-neck-shaped cylindrical micelle as a transition state. Although an increase of membrane tension facilitates the fission process by reducing the corresponding free-energy barrier, for biologically relevant tensions, the free-energy barriers still significantly exceed the thermal energy scale kBT.

  4. Systematics of fission cross sections at the intermediate energy region

    Energy Technology Data Exchange (ETDEWEB)

    Fukahori, Tokio; Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    The systematics was obtained with fitting experimental data for proton induced fission cross sections of Ag, {sup 181}Ta, {sup 197}Au, {sup 206,207,208}Pb, {sup 209}Bi, {sup 232}Th, {sup 233,235,238}U, {sup 237}Np and {sup 239}Pu above 20 MeV. The low energy cross section of actinoid nuclei is omitted from systematics study, since the cross section has a complicated shape and strongly depends on characteristic of nucleus. The fission cross sections calculated by the systematics are in good agreement with experimental data. (author)

  5. Superasymmetric fission at intermediate energy and production of neutron-rich nuclei with A

    NARCIS (Netherlands)

    Huhta, M; Dendooven, P; Honkanen, A; Jokinen, A; Lhersonneau, G; Oinonen, M; Penttila, H; Perajarvi, K; Rubchenya, VA; Aysto, J

    1997-01-01

    The yields of neutron-rich Ni, Cu, Zn, Ga and Ge-isotopes were measured in 25 MeV proton induced fission of U-238 using the ion guide-based isotope separator technique. The results indicate enhancement for superasymmetric mass division at intermediate excitation energy of the fissioning nucleus and

  6. Photon and proton induced fission on heavy nuclei at intermediate energies

    Directory of Open Access Journals (Sweden)

    Andrade-II E.

    2014-04-01

    Full Text Available We present an analysis of fission induced by intermediate energy protons or photons on actinides. The 660 MeV proton induced reactions are on 241Am, 238U, and 237Np targets and the Bremmstrahlung-photons with end-point energies at 50 MeV and 3500 MeV are on 232Th and 238U targets. The study was performed by means of the Monte Carlo simulation code CRISP. A multimodal fission extension was added to the code within an approach which accounts for the contribution of symmetric and asymmetric fission. This procedure allowed the investigation of fission cross sections, fissility, number of evaporated nucleons and fission-fragment charge distributions. The comparison with experimental data show a good agreement between calculations and experiments.

  7. Calculation for fission decay from heavy ion reactions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Blaich, T.; Begemann-Blaich, M.; Fowler, M.M.; Wilhelmy, J.B. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Britt, H.C.; Fields, D.J.; Hansen, L.F.; Namboodiri, M.N.; Sangster, T.C. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)); Fraenkel, Z. (Weizmann Institute of Science, 76100 Rehovot (Israel))

    1992-02-01

    A detailed deexcitation calculation is presented for target residues resulting from intermediate-energy heavy ion reactions. The model involves an intranuclear cascade, subsequent fast nucleon emission, and final decay by statistical evaporation including fission. Results are compared to data from bombardments with Fe and Nb projectiles on targets of Ta, Au, and Th at 100 MeV/nucleon. The majority of observable features are reproduced with this simple approach, making obvious the need for involving new physical phenomena associated with multifragmentation or other collective dissipation mechanisms.

  8. Cherenkov light detection as a velocity selector for uranium fission products at intermediate energies

    Science.gov (United States)

    Yamaguchi, T.; Enomoto, A.; Kouno, J.; Yamaki, S.; Matsunaga, S.; Suzaki, F.; Suzuki, T.; Abe, Y.; Nagae, D.; Okada, S.; Ozawa, A.; Saito, Y.; Sawahata, K.; Kitagawa, A.; Sato, S.

    2014-12-01

    The in-flight particle separation capability of intermediate-energy radioactive ion (RI) beams produced at a fragment separator can be improved with the Cherenkov light detection technique. The cone angle of Cherenkov light emission varies as a function of beam velocity. This can be exploited as a velocity selector for secondary beams. Using heavy ion beams available at the HIMAC synchrotron facility, the Cherenkov light angular distribution was measured for several thin radiators with high refractive indices (n = 1.9 ~ 2.1). A velocity resolution of ~10-3 was achieved for a 56Fe beam with an energy of 500 MeV/nucleon. Combined with the conventional rigidity selection technique coupled with energy-loss analysis, the present method will enable the efficient selection of an exotic species from huge amounts of various nuclides, such as uranium fission products at the BigRIPS fragment separator located at the RI Beam Factory.

  9. Cherenkov light detection as a velocity selector for uranium fission products at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, T., E-mail: yamaguti@phy.saitama-u.ac.jp [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Enomoto, A.; Kouno, J.; Yamaki, S.; Matsunaga, S.; Suzaki, F.; Suzuki, T. [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Abe, Y.; Nagae, D.; Okada, S.; Ozawa, A.; Saito, Y.; Sawahata, K. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Kitagawa, A.; Sato, S. [National Institute of Radiological Sciences, Chiba 263-8555 (Japan)

    2014-12-01

    The in-flight particle separation capability of intermediate-energy radioactive ion (RI) beams produced at a fragment separator can be improved with the Cherenkov light detection technique. The cone angle of Cherenkov light emission varies as a function of beam velocity. This can be exploited as a velocity selector for secondary beams. Using heavy ion beams available at the HIMAC synchrotron facility, the Cherenkov light angular distribution was measured for several thin radiators with high refractive indices (n=1.9∼2.1). A velocity resolution of ∼10{sup −3} was achieved for a {sup 56}Fe beam with an energy of 500 MeV/nucleon. Combined with the conventional rigidity selection technique coupled with energy-loss analysis, the present method will enable the efficient selection of an exotic species from huge amounts of various nuclides, such as uranium fission products at the BigRIPS fragment separator located at the RI Beam Factory. - Highlights: • The cone angle of Cherenkov light can be used as a velocity selector of RI beams. • Proof-of-principle experiments are made using heavy ions at intermediate energies. • Results demonstrate successful separation of RI beams produced by fragmentation. • A velocity resolution of 10{sup −3} is achieved for thin high refractive radiators.

  10. Angular distribution of fragments from neutron-induced fission of {sup 238}U in the intermediate energy region

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Magnus

    2004-06-01

    Areas ranging from nuclear structure models to accelerator-driven systems benefit from improved neutron-induced fission data in the intermediate energy region. In this Master's degree thesis, the fragment angular distribution from fission of {sup 238}U, induced by 21-MeV neutrons, has been analysed from an experiment performed with the Medley/DIFFICILE setup at the The Svedberg Laboratory in Uppsala. The data have been corrected for low energy neutrons in the beam. The results agree with other experiments, as well as with model calculations. The data should be a starting point for further analysis with a goal to deduce the fission cross-section of {sup 238}U.

  11. Emission of intermediate mass fragments during fission

    Science.gov (United States)

    Chen, S. L.; de Souza, R. T.; Cornell, E.; Davin, B.; Hamilton, T. M.; Hulbert, D.; Kwiatkowski, K.; Lou, Y.; Viola, V. E.; Korteling, R. G.; Wile, J. L.

    1996-11-01

    Ternary fission in the reaction 4He + 232Th at Elab=200 MeV has been observed. Intermediate mass fragments (IMF: 3fission. The widths of the energy spectra are relatively constant for neck fragments with Z>=4, suggesting little variability in the scission configurations. A linear dependence of on Z is observed for the neck IMFs. The observed trend is compared with a Coulomb trajectory model.

  12. On current ambiguity in the interpretation of fission at intermediate excitation energy

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, C., E-mail: schmitt@ganil.fr [Grand Accélérateur National d' Ions Lourds, CEA/DSM–CNRS/IN2P3, 14076 Caen (France); Mazurek, K. [The Niewodniczański Institute of Nuclear Physics – PAN, 31-342 Kraków (Poland); Nadtochy, P.N. [Omsk State University, Department of Theoretical Physics, 644077 Omsk (Russian Federation)

    2014-10-07

    Various approaches are currently used to interpret experimental data on fission. We critically examine a wide set of observables measured for fission of {sup 206,210}Po nuclei at medium excitation energy, and illustrate the ambiguity in current analysis. Dynamical calculations based on the four-dimensional Langevin equation using a macroscopic potential energy landscape are performed, and found to consistently describe available measurements. This observation calls into question the robustness of recent analysis based on statistical-model calculations and concluding, on the contrary, to substantial shell effects at the fission saddle point in {sup 206,210}Po. The inconsistency in interpretation reached by the two approaches shows that, depending on the system, the conclusion can be strongly model-dependent. Although this may not be surprising, it emphasizes the today still limited reliability of firmly extracting fundamental nuclear properties from customary analysis.

  13. On current ambiguity in the interpretation of fission at intermediate excitation energy

    Directory of Open Access Journals (Sweden)

    C. Schmitt

    2014-10-01

    Full Text Available Various approaches are currently used to interpret experimental data on fission. We critically examine a wide set of observables measured for fission of Po206,210 nuclei at medium excitation energy, and illustrate the ambiguity in current analysis. Dynamical calculations based on the four-dimensional Langevin equation using a macroscopic potential energy landscape are performed, and found to consistently describe available measurements. This observation calls into question the robustness of recent analysis based on statistical-model calculations and concluding, on the contrary, to substantial shell effects at the fission saddle point in Po206,210. The inconsistency in interpretation reached by the two approaches shows that, depending on the system, the conclusion can be strongly model-dependent. Although this may not be surprising, it emphasizes the today still limited reliability of firmly extracting fundamental nuclear properties from customary analysis.

  14. Fission dynamics with systems of intermediate fissility

    Indian Academy of Sciences (India)

    E Vardaci; A Di Nitto; P N Nadtochy; A Brondi; G La Rana; R Moro; M Cinausero; G Prete; N Gelli; E M Kozulin; G N Knyazheva; I M Itkis

    2015-08-01

    A 4 light charged particle spectrometer, called 8 LP, is in operation at the Laboratori Nazionali di Legnaro, Italy, for studying reaction mechanisms in low-energy heavy-ion reactions. Besides about 300 telescopes to detect light charged particles, the spectrometer is also equipped with an anular PPAC system to detect evaporation residues and a two-arm time-of-flight spectrometer to detect fission fragments. The spectrometer has been used in several fission dynamics studies using as a probe light charged particles in the fission and evaporation residues (ER) channels. This paper proposes a journey within some open questions about the fission dynamics and a review of the main results concerning nuclear dissipation and fission time-scale obtained from several of these studies. In particular, the advantages of using systems of intermediate fissility will be discussed.

  15. Systematics of Proton-Induced Fission Cross Sections for Intermediate Energy Applications

    CERN Document Server

    Prokofiev, A V; Wilson, W B

    2002-01-01

    The recent systematics of proton-induced fission cross sections is extended to a wider range of target nuclei and incident energies. Reasonable agreement with available experimental data is demonstrated. The extended systematics is employed to generate a data library for use in the CINDER'90 transmutation inventory code.

  16. Theoretical and experimental studies of the neutron rich fission product yields at intermediate energies

    Directory of Open Access Journals (Sweden)

    Äystö J.

    2012-02-01

    Full Text Available A new method to measure the fission product independent yields employing the ion guide technique and a Penning trap as a precision mass filter, which allows an unambiguous identification of the nuclides is presented. The method was used to determine the independent yields in the proton-induced fission of 232Th and 238U at 25 MeV. The data were analyzed with the consistent model for description of the fission product formation cross section at the projectile energies up to 100 MeV. Pre-compound nucleon emission is described with the two-component exciton model using Monte Carlo method. Decay of excited compound nuclei is treated within time-dependent statistical model with inclusion of the nuclear friction effect. The charge distribution of the primary fragment isobaric chain was considered as a result of frozen quantal fluctuations of the isovector nuclear density. The theoretical predictions of the independent fission product cross sections are used for normalization of the measured fission product isotopic distributions.

  17. Fission Fragment Mass Distributions and Total Kinetic Energy Release of 235-Uranium and 238-Uranium in Neutron-Induced Fission at Intermediate and Fast Neutron Energies

    Energy Technology Data Exchange (ETDEWEB)

    Duke, Dana Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-12

    This Ph.D. dissertation describes a measurement of the change in mass distributions and average total kinetic energy (TKE) release with increasing incident neutron energy for fission of 235U and 238U. Although fission was discovered over seventy-five years ago, open questions remain about the physics of the fission process. The energy of the incident neutron, En, changes the division of energy release in the resulting fission fragments, however, the details of energy partitioning remain ambiguous because the nucleus is a many-body quantum system. Creating a full theoretical model is difficult and experimental data to validate existing models are lacking. Additional fission measurements will lead to higher-quality models of the fission process, therefore improving applications such as the development of next-generation nuclear reactors and defense. This work also paves the way for precision experiments such as the Time Projection Chamber (TPC) for fission cross section measurements and the Spectrometer for Ion Determination in Fission (SPIDER) for precision mass yields.

  18. A hemi-fission intermediate links two mechanistically distinct stages of membrane fission.

    Science.gov (United States)

    Mattila, Juha-Pekka; Shnyrova, Anna V; Sundborger, Anna C; Hortelano, Eva Rodriguez; Fuhrmans, Marc; Neumann, Sylvia; Müller, Marcus; Hinshaw, Jenny E; Schmid, Sandra L; Frolov, Vadim A

    2015-08-06

    Fusion and fission drive all vesicular transport. Although topologically opposite, these reactions pass through the same hemi-fusion/fission intermediate, characterized by a 'stalk' in which only the outer membrane monolayers of the two compartments have merged to form a localized non-bilayer connection. Formation of the hemi-fission intermediate requires energy input from proteins catalysing membrane remodelling; however, the relationship between protein conformational rearrangements and hemi-fusion/fission remains obscure. Here we analysed how the GTPase cycle of human dynamin 1, the prototypical membrane fission catalyst, is directly coupled to membrane remodelling. We used intramolecular chemical crosslinking to stabilize dynamin in its GDP·AlF4(-)-bound transition state. In the absence of GTP this conformer produced stable hemi-fission, but failed to progress to complete fission, even in the presence of GTP. Further analysis revealed that the pleckstrin homology domain (PHD) locked in its membrane-inserted state facilitated hemi-fission. A second mode of dynamin activity, fuelled by GTP hydrolysis, couples dynamin disassembly with cooperative diminishing of the PHD wedging, thus destabilizing the hemi-fission intermediate to complete fission. Molecular simulations corroborate the bimodal character of dynamin action and indicate radial and axial forces as dominant, although not independent, drivers of hemi-fission and fission transformations, respectively. Mirrored in the fusion reaction, the force bimodality might constitute a general paradigm for leakage-free membrane remodelling.

  19. Nucleon-induced fission cross-sections of tantalum and separated tungsten isotopes and "compound nucleus" effect in intermediate energy region

    CERN Document Server

    Smirnov, A N; Eismont, V P; Filatov, N P; Blomgren, J; Conde, H; Prokofiev, A V; Mashnik, S G

    2007-01-01

    Neutron- and proton-induced fission cross-sections of separated isotopes of tungsten (182W, 183W, 184W, and 186W) and 181Ta relative to 209Bi have been measured in the incident nucleon energy region 50 - 200 MeV using fission chambers based on thin-film breakdown counters (TFBC) using quasi-monoenergetic neutrons from the 7Li(p,n) reaction and at the proton beams of The Svedberg Laboratory (TSL), Uppsala University (Uppsala, Sweden). The results are compared with predictions by the CEM03.01 event generator, as well as with the recent data for nuclei in the lead-bismuth region. The effect of "compound nucleus" in the intermediate energy region is discussed, displaying in exponential dependence of nucleon-induced fission cross-sections on the parameter Z^2/A of the composite system (projectile+target nucleus), and in other characteristics of the fission process for which parameter Z^2/A plays a role similar to the one of the usual liquid-drop parameter Z^2/A of compound nuclei.

  20. Neck Emission of Intermediate Mass Fragments During Fission

    Science.gov (United States)

    de Souza, R. T.; Chen, S. L.; Cornell, E. W.; Davin, B.; Hamilton, T. M.; Hulburt, D.; Kwiatkowski, K.; Lou, Y.; Viola, V. E.; Wile, J. L.; Korteling, R.

    1996-05-01

    Ternary fission of heavy nuclei provides a unique opportunity to constrain models of the dissipative forces which occur during fission. We have measured neck emission of Intermediate mass fragments (IMF:3 model are made.

  1. Intrinsic energy partition in fission

    Directory of Open Access Journals (Sweden)

    Mirea M.

    2013-03-01

    Full Text Available The intrinsic energy partition between two complementary fission fragments is investigated microscopically. The intrinsic excitation energy of fission fragments is dynamically evaluated in terms of the time-dependent pairing equations. These equations are corroborated with two conditions. One of them fixes the number of particles and the other separates the pairing active spaces associated to the two fragments in the vicinity of the scission configuration. The excitation energy in a wide distribution of fission fragments is calculated for the 234U parent nucleus.

  2. Energy from nuclear fission(*

    Directory of Open Access Journals (Sweden)

    Ripani M.

    2015-01-01

    Full Text Available The main features of nuclear fission as physical phenomenon will be revisited, emphasizing its peculiarities with respect to other nuclear reactions. Some basic concepts underlying the operation of nuclear reactors and the main types of reactors will be illustrated, including fast reactors, showing the most important differences among them. The nuclear cycle and radioactive-nuclear-waste production will be also discussed, along with the perspectives offered by next generation nuclear assemblies being proposed. The current situation of nuclear power in the world, its role in reducing carbon emission and the available resources will be briefly illustrated.

  3. A study of potential high band-gap photovoltaic materials for a two step photon intermediate technique in fission energy conversion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Prelas, M.A.

    1996-01-24

    This report describes progress made to develop a high bandgap photovoltaic materials for direct conversion to electricity of excimer radiation produced by fission energy pumped laser. This report summarizes the major achievements in sections. The first section covers n-type diamond. The second section covers forced diffusion. The third section covers radiation effects. The fourth section covers progress in Schottky barrier and heterojunction photovoltaic cells. The fifth section covers cell and reactor development.

  4. Energy partition in low energy fission

    CERN Document Server

    Mirea, M

    2011-01-01

    The intrinsic excitation energy of fission fragments is dynamically evaluated in terms of the time dependent pairing equations. These equations are corroborated with two conditions. One of them fixes the number of particles and the another separates the pairing active spaces associated to the two fragments in the vicinity of the scission configuration. The fission path is obtained in the frame of the macroscopic-microscopic model. The single particle level schemes are obtained within the two center Woods-Saxon shell model. It is shown that the available intrinsic dissipated energy is not shared proportionally to the masses of the two fission fragments. If the heavy fragment possesses nucleon numbers close to the magic ones, the accumulated intrinsic excitation energy is lower than that of the light fragment.

  5. Fission dynamics at low excitation energy

    CERN Document Server

    Aritomo, Y

    2013-01-01

    The origin of mass asymmetry in the fission of uranium at a low excitation energy is clarified by a trajectory analysis of the Langevin equation. The positions of the peaks in the mass distribution of fission fragments are mainly determined by fission saddle points originating from the shell correction energy. The widths of the peaks, on the other hand, result from a shape fluctuation around the scission point caused by the random force in the Langevin equation. We found that a random vibration in the oblate direction of fissioning fragments is essential for the fission process. According to this picture, fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup. This is expected to lead to a new viewpoint of fission dynamics and the splitting mechanism.

  6. Nuclear dissipation effects on fission and evaporation in systems of intermediate fissility

    Directory of Open Access Journals (Sweden)

    Gelli N.

    2010-03-01

    Full Text Available The systems of intermediate fissility 132Ce and 158Er have been studied experimentally and theoretically in order to investigate the dissipation properties of nuclear matter. Cross sections of fusion-fission and evaporation residues channels together with charged particles multiplicities in both channels, their spectra, angular correlations and mass-energy distribution of fission fragments have been measured. Theoretical analysis has been performed using multi-dimensional stochastic approach with realistic treatment of particle evaporation. The results of analysis show that full one-body or unusually strong two-body dissipation allows to reproduce experimental data. No temperature dependent dissipation was needed.

  7. Fission dynamics at low excitation energy. 2

    CERN Document Server

    Aritomo, Y; Ivanyuk, F A

    2014-01-01

    The mass asymmetry in the fission of U-236 at low excitation energy is clarified by the analysis of the trajectories obtained by solving the Langevin equations for the shape degrees of freedom. It is demonstrated that the position of the peaks in the mass distribution of fission fragments is determined mainly by the saddle point configuration originating from the shell correction energy. The width of the peaks, on the other hand, results from the shape fluctuations close to the scission point caused by the random force in the Langevin equation. We have found out that the fluctuations between elongated and compact shapes are essential for the fission process. According to our results the fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup, but is accompanied by the fluctuations between elongated and compact shapes. This picture presents a new viewpoint of fission dynamics and the splitting mechanism.

  8. Energy from nuclear fission an introduction

    CERN Document Server

    De Sanctis, Enzo; Ripani, Marco

    2016-01-01

    This book provides an overview on nuclear physics and energy production from nuclear fission. It serves as a readable and reliable source of information for anyone who wants to have a well-balanced opinion about exploitation of nuclear fission in power plants. The text is divided into two parts; the first covers the basics of nuclear forces and properties of nuclei, nuclear collisions, nuclear stability, radioactivity, and provides a detailed discussion of nuclear fission and relevant topics in its application to energy production. The second part covers the basic technical aspects of nuclear fission reactors, nuclear fuel cycle and resources, safety, safeguards, and radioactive waste management. The book also contains a discussion of the biological effects of nuclear radiation and of radiation protection, and a summary of the ten most relevant nuclear accidents. The book is suitable for undergraduates in physics, nuclear engineering and other science subjects. However, the mathematics is kept at a level that...

  9. Energy-loss distributions of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Demidovich, N.N.; Nakhutin, I.E.; Shatunov, V.G.

    1976-03-05

    The f-f coincidence method was used to investigate the change in the form of the energy-loss distributions of Cf/sup 252/ fission fragments in air, down to fragment energies approx.0.8 MeV. A theoretical model is considered for the estimate of the mean-squared deviations of the fragment energy-loss distributions. (AIP)

  10. Photofissility of heavy nuclei at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Deppman, A.; Arruda Neto, J.D.T.; Likhachev, V.P. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Tavares, O.A.P.; Duarte, S.B.; Oliveira, E.C. de [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Goncalves, M. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)

    2002-10-01

    We use the recently developed MCMC/MCEF (Multi Collisional Monte Carlo plus Monte Carlo for Evaporation-Fission calculations) model to calculate the photo fissility and the photofission cross section at intermediate energies for the {sup 243} Am and for {sup 209} Bi, and compare them to results obtained for other actinides and to available experimental data. As expected, the results for {sup 243} Am are close to those for {sup 237} Np. The fissility for pre actinide nuclei is nearly one order of magnitude lower than that for the actinides. Both fissility and photofission cross section for {sup 209} Bi are in good agreement with the experimental data. (author)

  11. Fission energy program of the US Department of Energy, FY 1981

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, Robert L.

    1980-03-01

    Information is presented concerning the National Energy Plan and fission energy policy; fission energy program management; converter reactor systems; breeder reactor systems; and special nuclear evaluations and systems.

  12. Derivation of Energy Generated by Nuclear Fission-Fusion Reaction

    OpenAIRE

    Kayano, Hideo; Teshigawara, Makoto; Konashi, Kenji; Yamamoto, Takuya

    1994-01-01

    In the solids which contain fissionable elements and deuterium, it is expected that the energy generated by nuclear fission contributes to the promotion of the D-D nuclear fusion in the solids. When nuclear fission occurs by neutrons in the solid, the fissionable elements divide into two fission product nuclei having the energy of 100MeV, respectively. It is expected that the hige energy fission products promote rapidly nuclear fision reaction by knocking out the D atoms in the solids and by ...

  13. Excitation-energy dependence of the nuclear fission characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Baba, H.; Saito, T.; Takahashi, N. [Osaka City Univ. (Japan). Faculty of Science] [and others

    1996-03-01

    It is known that the width parameter of the fragment mass yield distribution follows a beautiful systematics with respect to the excitation energy. According to this systematics, the fission characteristics following the systematics should disappear when the excitation energy Ex goes down to 14 MeV. The present purpose is to elucidate if, where, how and why a transition takes place in the fission characteristics of the asymmetric fission of light actinide elements. Two types of experiments are performed, one is the double-energy measurement of the kinetic energies of complementary fragments in the thermal-neutron fission of {sup 235,233}U and proton-induced fission of {sup 238}U at 13.3- and 15.7-MeV excitations, and the other is the radiochemical study of proton-induced fission and photofission of {sup 238}U at various excitation energies. In conclusion, it has demonstrated that there are two distinctive fission mechanisms in the low-energy fission of light actinide elements and the transition between them takes place around 14-MeV excitation. The characteristics of proton fission and photofission in the energy range lower than the above transition point are the essentially the same as those of thermal-neutron fission and also spontaneous fission. The results of GDR fission indicates the fission in the high-energy side starts from the nuclear collective states, whereas the lower-energy fission is of non-collective nature. It is likely that thermal-neutron fission is rather of the barrier-penetrating type like spontaneous fission than the threshold fission. (S.Y.)

  14. Effects of fissioning nuclei distributions on fragment mass distributions for high energy fission

    Directory of Open Access Journals (Sweden)

    Rossi P C R

    2012-02-01

    Full Text Available We study the effects of fissioning nuclei mass- and energy-distributions on the formation of fragments for fission induced by high energy probes. A Monte Carlo code called CRISP was used for obtaining mass distributions and spectra of the fissioning nuclei for reactions induced by 660 MeV protons on 241Am and on 239Np, by 500 MeV protons on 208Pb, and by Bremsstrahlung photons with end-point energies at 50 MeV and 3500 MeV on 238U. The results show that even at high excitation energies, asymmetric fission may still contribute significantly to the fission cross section of actinide nuclei, while it is the dominante mode in the case of lead. However, more precise data for high energy fission on actinide are necessary in order to allow definite conclusions.

  15. Evolution of isotopic fission-fragment yields with excitation energy

    Directory of Open Access Journals (Sweden)

    Bazin D.

    2012-07-01

    Full Text Available Two fission experiments have been performed at GANIL using 238U beams at different energies and light targets. Different fissioning systems were produced with excitation energies from 10 to 230 MeV and their decay by fission was investigated with GANIL spectrometers. Preliminary fission-fragment isotopic distributions have been obtained. The evolution with impinging energy of their properties, the neutron excess and the width of the neutron-number distributions, gives important insights into the dynamics of fusion-fission mechanism.

  16. Fusion-fission energy systems evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Teofilo, V.L.; Aase, D.T.; Bickford, W.E.

    1980-01-01

    This report serves as the basis for comparing the fusion-fission (hybrid) energy system concept with other advanced technology fissile fuel breeding concepts evaluated in the Nonproliferation Alternative Systems Assessment Program (NASAP). As such, much of the information and data provided herein is in a form that meets the NASAP data requirements. Since the hybrid concept has not been studied as extensively as many of the other fission concepts being examined in NASAP, the provided data and information are sparse relative to these more developed concepts. Nevertheless, this report is intended to provide a perspective on hybrids and to summarize the findings of the rather limited analyses made to date on this concept.

  17. Energy Partition in n+233U Fission Reaction

    Institute of Scientific and Technical Information of China (English)

    CHEN; Yong-jing; LIU; Ting-jin; SHU; Neng-chuan

    2012-01-01

    <正>The partition of the total excitation energy between the fission fragments for the n+233U fission reactions are analyzed with a semi-empirical model, and it is a key point for calculating the prompt fission neutron spectrum, and it is still a long-standing problem for nuclear fission, and attracts more and more attention. With the available experimental data, such as the average total number of emitted neutrons, the

  18. Nuclear reactions at intermediate energies

    Directory of Open Access Journals (Sweden)

    Shyam Radhey

    2016-01-01

    Full Text Available In the domain of Nuclear reactions at intermediate energies, the QCD coupling constant αs is large enough (~ 0.3 - 0.5 to render the perturbative calculational techniques inapplicable. In this regime the quarks are confined into colorless hadrons and it is expected that effective field theories of hadron interactions via exchange of hadrons, provide useful tools to describe such reactions. In this contribution we discuss the application of one such theory, the effective Lagrangian model, in describing the hadronic reactions at intermediate energies whose measurements are the focus of a vast international experimental program.

  19. Structural materials for fission & fusion energy

    Directory of Open Access Journals (Sweden)

    Steven J. Zinkle

    2009-11-01

    Full Text Available Structural materials represent the key for containment of nuclear fuel and fission products as well as reliable and thermodynamically efficient production of electrical energy from nuclear reactors. Similarly, high-performance structural materials will be critical for the future success of proposed fusion energy reactors, which will subject the structures to unprecedented fluxes of high-energy neutrons along with intense thermomechanical stresses. Advanced materials can enable improved reactor performance via increased safety margins and design flexibility, in particular by providing increased strength, thermal creep resistance and superior corrosion and neutron radiation damage resistance. In many cases, a key strategy for designing high-performance radiation-resistant materials is based on the introduction of a high, uniform density of nanoscale particles that simultaneously provide good high temperature strength and neutron radiation damage resistance.

  20. Intermediate structure in the keV fission cross section of /sup 235/U

    Energy Technology Data Exchange (ETDEWEB)

    Migneco, E. (Univ., Catania, Italy); Bonsignore, P.; Lanzano, G.; Wartena, J.A.; Weigmann, H.

    1975-10-01

    The relative fission cross section of /sup 235/U has been measured up to 200 keV with a nominal resolution of 1.0 ns/m, using a thin foil plastic scintillator detector. The data have been analyzed in order to detect nonstatistical effects due to intermediate structure. Statistical tests which have been applied to this fission and similar total cross section data include calculations of the auto-correlation function and Wald-Wolfowitz tests on the cross section and on the autocorrelograms. The comparison of the results indicates the presence of intermediate structure effects in fission cross-section which may be interpreted on the basis of the double-humped deformation potential. 5 figures. (auth)

  1. Proton induced fission of 181-Ta at relativistic energies

    CERN Document Server

    Ayyad, Y; Casarejos, E; Álvarez-Pol, H; Bacquias, A; Boudard, A; Caamaño, M; Enqvist, T; Föhr, V; Kelić-Heil, A; Kezzar, K; Leray, S; Paradela, C; Pérez-Loureiro, D; Pleskač, R; Tarrío, D

    2012-01-01

    Total fission cross sections of 181-Ta induced by protons at different relativistic energies have been measured at GSI, Darmstadt. The inverse kinematics technique used together with a dedicated set-up, made it possible to determine these cross sections with high accuracy. The new data obtained in this experiment will contribute to the understanding of the fission process at high excitation energies. The results are compared with data from previous experiments and systematics for proton-induced fission cross sections.

  2. Generalized Energy-Dependent Q Values for Fission

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R

    2010-03-31

    We extend Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q value for major and minor actinides on the incident neutron energies in the range 0 {le} E{sub n} {le} 20 MeV. Our parameterization is based on the actinide evaluations recommended for the ENDF/B-VII.1 release. This paper describes the calculation of energydependent fission Q values based on the calculation of the prompt energy release in fission by Madland. This calculation was adopted for use in the LLNL ENDL database and then generalized to obtain the prompt fission energy release for all actinides. Here the calculation is further generalized to the total energy release in fission. There are several stages in a fission event, depending on the time scale. Neutrons and gammas may be emitted at any time during the fission event.While our discussion here is focussed on compound nucleus creation by an incident neutron, similar parameterizations could be obtained for incident gammas or spontaneous fission.

  3. Fission-fragment energy correlation measurements for the spontaneous fission of /sup 244/Cm

    Energy Technology Data Exchange (ETDEWEB)

    Caitucoli, F.; Leroux, B.; Barreau, G.; Sicre, A.; Doan, T.P. (Bordeaux-1 Univ., 33 - Gradignan (France). Centre d' Etudes Nucleaires); Asghar, M.; Hamadache, K.; Allab, M. (Centre des Sciences et de la Technologie Nucleaires, Algiers (Algeria))

    1983-02-28

    Fission-fragment mass and kinetic energy distributions and their correlations have been measured for the spontaneous fission of /sup 244/Cm. About 3.54 x 10/sup 5/ fission events were collected. The global mass distribution shows shoulders at ..mu..sub(H) approx.= 134 and ..mu..sub(H) approx.= 143-144. The peak/valley ratio is 86. The dip ..delta..Esub(K) value at symmetry is 13.4 +- 1.5 MeV. In the yields for high-kinetic-energy selected events, the masses 139 and 144 dominate. The results of /sup 244/Cm are compared with the other isotopes of Cm and discussed in terms of the structures present in the potential energy surface of the fissioning system caused by the structures in the nascent fragments.

  4. Mass and energy dependence of pion-induced fission

    Science.gov (United States)

    Peterson, R. J.; Debarros, S.; Desouza, I. O.; Gaspar, M. B.; Khan, Hameed Ahmed; Manzoor, Shahid

    1995-06-01

    Data for fission induced by pi meson beams from 80 to 500 MeV are presented for nuclei from Fe through Pu as measured by solid state track detectors. The general trends for binary fission with π + are reproduced fairly well by a calculation in the ‘high excitation’ limit with standard level density and fission barrier parameters, but π - data are underpredicted. A universal dependence of the binary fission probabilities with the fissility ( Z±1)2/A is found to be valid for both pion beam charges for all beam energies below the delta resonance. Probabilities for observing three fragments with π + are not reproduced by a ternary fission application of the model found to work for binary fission.

  5. Study on fission blanket fuel cycling of a fusion-fission hybrid energy generation system

    Science.gov (United States)

    Zhou, Z.; Yang, Y.; Xu, H.

    2011-10-01

    This paper presents a preliminary study on neutron physics characteristics of a light water cooled fission blanket for a new type subcritical fusion-fission hybrid reactor aiming at electric power generation with low technical limits of fission fuel. The major objective is to study the fission fuel cycling performance in the blanket, which may possess significant impacts on the feasibility of the new concept of fusion-fission hybrid reactor with a high energy gain (M) and tritium breeding ratio (TBR). The COUPLE2 code developed by the Institute of Nuclear and New Energy Technology of Tsinghua University is employed to simulate the neutronic behaviour in the blanket. COUPLE2 combines the particle transport code MCNPX with the fuel depletion code ORIGEN2. The code calculation results show that soft neutron spectrum can yield M > 20 while maintaining TBR >1.15 and the conversion ratio of fissile materials CR > 1 in a reasonably long refuelling cycle (>five years). The preliminary results also indicate that it is rather promising to design a high-performance light water cooled fission blanket of fusion-fission hybrid reactor for electric power generation by directly loading natural or depleted uranium if an ITER-scale tokamak fusion neutron source is achievable.

  6. Energy-Dependent Fission Q Values Generalized for All Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R

    2008-09-25

    We generalize Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q values on incident neutron energy, E{sub n}, for all major and minor actinides. These Q(E{sub n}) parameterizations are included in the ENDL2008 release. This paper describes calculations of energy-dependent fission Q values based on parameterizations of the prompt energy release in fission [1], developed by Madland [1] to describe the prompt energy release in neutron-induced fission of {sup 235}U, {sup 238}U, and {sup 239}Pu. The energy release is then related to the energy deposited during fission so that experimentally measurable quantities can be used to obtain the Q values. A discussion of these specific parameterizations and their implementation in the processing code for Monte Carlo neutron transport, MCFGEN, [2] is described in Ref. [3]. We extend this model to describe Q(E) for all actinides, major and minor, in the Evaluated Nuclear Data Library (ENDL) 2008 release, ENDL2008.

  7. Experiments in intermediate energy physics

    Energy Technology Data Exchange (ETDEWEB)

    Dehnhard, D.

    2003-02-28

    Research in experimental nuclear physics was done from 1979 to 2002 primarily at intermediate energy facilities that provide pion, proton, and kaon beams. Particularly successful has been the work at the Los Alamos Meson Physics Facility (LAMPF) on unraveling the neutron and proton contributions to nuclear ground state and transition densities. This work was done on a wide variety of nuclei and with great detail on the carbon, oxygen, and helium isotopes. Some of the investigations involved the use of polarized targets which allowed the extraction of information on the spin-dependent part of the triangle-nucleon interaction. At the Indiana University Cyclotron Facility (IUCF) we studied proton-induced charge exchange reactions with results of importance to astrophysics and the nuclear few-body problem. During the first few years, the analysis of heavy-ion nucleus scattering data that had been taken prior to 1979 was completed. During the last few years we created hypernuclei by use of a kaon beam at Brookhaven National Laboratory (BNL) and an electron beam at Jefferson Laboratory (JLab). The data taken at BNL for a study of the non-mesonic weak decay of the A particle in a nucleus are still under analysis by our collaborators. The work at JLab resulted in the best resolution hypernuclear spectra measured thus far with magnetic spectrometers.

  8. INTERMEDIATE-ENERGY LIGHT SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Corbett, William

    2002-11-25

    from each port can be subdivided into several separate beams, each of which can serve an independent experimental station. All told, 50 or more scientific teams can simultaneously and independently conduct research using intense photon beams from a single intermediate-energy synchrotron radiation facility.

  9. Fission fragment energy correlation measurements for Cf-252(SF)

    Energy Technology Data Exchange (ETDEWEB)

    Barreau, G.; Sicre, A.; Caitucoli, F.; Doan, T.P.; Leroux, B.; Martinez, G.; Asghar, M.; Benfoughal, T.

    1986-01-01

    The mean total kinetic energy, its variance and to a lesser extent the mass yield show strong and correlated fluctuations. These structures are discussed in terms of the static macro-microscopic potential energy calculations. The cold fission mass yield distribution exhibits a fine structure which results from an odd-even effect on nuclear charge.

  10. Analytic computation of average energy of neutrons inducing fission

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Alexander Rich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-12

    The objective of this report is to describe how I analytically computed the average energy of neutrons that induce fission in the bare BeRP ball. The motivation of this report is to resolve a discrepancy between the average energy computed via the FMULT and F4/FM cards in MCNP6 by comparison to the analytic results.

  11. Excitation energy dependence of fission in the mercury region

    CERN Document Server

    McDonnell, J D; Sheikh, J A; Staszczak, A; Warda, M

    2014-01-01

    Background: Recent experiments on beta-delayed fission reported an asymmetric mass yield in the neutron-deficient nucleus 180Hg. Earlier experiments in the mass region A=190-200 close to the beta-stability line, using the (p,f) and (\\alpha,f) reactions, observed a more symmetric distribution of fission fragments. While the beta-delayed fission of 180Hg can be associated with relatively low excitation energy, this is not the case for light-ion reactions, which result in warm compound nuclei. Purpose: To elucidate the roles of proton and neutron numbers and excitation energy in determining symmetric and asymmetric fission yields, we compute and analyze the isentropic potential energy surfaces of 174,180,198Hg and 196,210Po. Methods: We use the finite-temperature superfluid nuclear density functional theory, for excitation energies up to E*=30MeV and zero angular momentum. For our theoretical framework, we consider the Skyrme energy density functional SkM* and a density-dependent pairing interaction. Results: Fo...

  12. Fragment Deexcitation of Fission Induced by High Energy Nucleons

    Directory of Open Access Journals (Sweden)

    Yavshits S.

    2010-03-01

    Full Text Available The KRIF library of the neutron-, proton- and gamma-spectra emitted by the nuclei excited up to 500 MeV is presented. The KRIF contains information for about 2000 emitters which are the fragments of the ten targets fission induced by the nucleons with the energies up to 3 GeV.

  13. Excitation-energy sorting in superfluid fission dynamics

    Directory of Open Access Journals (Sweden)

    Schmidt K.-H.

    2010-10-01

    Full Text Available It is now well established that at moderate excitation energies the nucleus temperature does not vary with increasing excitation energy. We show that, as a consequence, two nuclei with different temperatures brought into contact show a rather surprising energy-sorting mechanism where the hotter nucleus transfers all its excitation energy to the colder one. The scission configuration of the fission process offers a unique possibility to observe this phenomenon. The energy-sorting mechanism is clearly reflected by the mean number of prompt neutrons as a function of the fragment mass and by the dependence of the local even-odd effect with mass asymmetry.

  14. Intermediate-energy light sources

    CERN Document Server

    Corbett, W

    2003-01-01

    Increasingly, atomic scale information underlies scientific and technological progress in disciplines ranging from pharmaceutical development to materials synthesis to environmental remediation. While a variety of research tools are used to provide atomic scale information, synchrotron radiation has proved invaluable in this quest. The rapid growth of soft- and hard X-ray synchrotron light sources stands as stark testimony to the importance and utility of synchrotron radiation. Starting from just a handful of synchrotron light sources in the early 1970s, this burgeoning field now includes over 70 proposed, in-construction, or operating facilities in 23 countries on five continents. Along the way, synchrotron light facilities have evolved from small laboratories extracting light parasitically from storage rings designed for high-energy physics research to large, dedicated sources using the latest technology to produce extraordinarily bright photon beams. The basic layout of a multi-GeV storage ring light sourc...

  15. Intermediate-energy nuclear chemistry workshop

    Energy Technology Data Exchange (ETDEWEB)

    Butler, G.W.; Giesler, G.C.; Liu, L.C.; Dropesky, B.J.; Knight, J.D.; Lucero, F.; Orth, C.J.

    1981-05-01

    This report contains the proceedings of the LAMPF Intermediate-Energy Nuclear Chemistry Workshop held in Los Alamos, New Mexico, June 23-27, 1980. The first two days of the Workshop were devoted to invited review talks highlighting current experimental and theoretical research activities in intermediate-energy nuclear chemistry and physics. Working panels representing major topic areas carried out indepth appraisals of present research and formulated recommendations for future research directions. The major topic areas were Pion-Nucleus Reactions, Nucleon-Nucleus Reactions and Nuclei Far from Stability, Mesonic Atoms, Exotic Interactions, New Theoretical Approaches, and New Experimental Techniques and New Nuclear Chemistry Facilities.

  16. Laser Inertial Fusion-based Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System

    OpenAIRE

    Kramer, Kevin James

    2010-01-01

    This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by ...

  17. Investigation of 11B+197Au Reaction at Intermediate Energies

    CERN Document Server

    Karapetyan, G S; Balabekyan, A R

    2016-01-01

    Mechanism of nuclear reactions on 197Au induced by 11B ions at energies above Coulomb barrier was studied by induced-activity method and gamma-spectroscopy. The cross sections of the reaction fragments from 197Au induced by 11B ions were measured at bombarding energies 137.5 and 255.5 MeV. The fission process was investigated by using multimodal fission approach at the energy 137.5 MeV, and pure symmetric distribution at 255.5 MeV. It was observed that the transferred linear momentum provides the information on the initial projectile-target information. The fissility for both fission reactions under study was deduced from measured fission cross section using the total inelastic cross section. Comparison with proton-induced fission shown, that the linear momentum transferred to the fissile system depends on the probe.

  18. Comparative evaluation of solar, fission, fusion, and fossil energy resources. Part 2: Power from nuclear fission

    Science.gov (United States)

    Clement, J. D.

    1973-01-01

    Different types of nuclear fission reactors and fissionable materials are compared. Special emphasis is placed upon the environmental impact of such reactors. Graphs and charts comparing reactor facilities in the U. S. are presented.

  19. Viscosity and fission time scale of Dy-156 at high excitation energies and large angular momenta

    NARCIS (Netherlands)

    vantHof, G; Bacelar, JCS; Dioszegi, [No Value; Harakeh, MN; Hesselink, WHA; KalantarNayestanaki, N; Kugler, A; vanderPloeg, H; Plompen, AJM; vanSchagen, JPS

    1996-01-01

    The reaction Ar-40 + Cd-116 --> Dy-156* --> fission as Studied at beam energies E(b) = 216 MeV and E(b) = 238 MeV, wherein gamma-rays were measured in coincidence with fission fragments. From these spectra the nuclear viscosity gamma and fission time scale were deduced by comparing to statistical

  20. Delayed fission

    Energy Technology Data Exchange (ETDEWEB)

    Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-07-01

    Delayed fission is a nuclear decay process that couples {beta} decay and fission. In the delayed fission process, a parent nucleus undergoes {beta} decay and thereby populates excited states in the daughter. If these states are of energies comparable to or greater than the fission barrier of the daughter, then fission may compete with other decay modes of the excited states in the daughter. In this paper, mechanism and some experiments of the delayed fission will be discussed. (author)

  1. Proceedings of the Second Fusion-Fission Energy Systems Review Meeting

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-11-02

    The agenda of the meeting was developed to address, in turn, the following major areas: specific problem areas in nuclear energy systems for application of fusion-fission concepts; current and proposed fusion-fission programs in response to the identified problem areas; target costs and projected benefits associated with fusion-fission energy systems; and technical problems associated with the development of fusion-fission concepts. The greatest emphasis was placed on the characteristics of and problems, associated with fuel producing fusion-fission hybrid reactors.

  2. Proceedings of the Second Fusion-Fission Energy Systems Review Meeting

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-11-02

    The agenda of the meeting was developed to address, in turn, the following major areas: specific problem areas in nuclear energy systems for application of fusion-fission concepts; current and proposed fusion-fission programs in response to the identified problem areas; target costs and projected benefits associated with fusion-fission energy systems; and technical problems associated with the development of fusion-fission concepts. The greatest emphasis was placed on the characteristics of and problems, associated with fuel producing fusion-fission hybrid reactors.

  3. The Power Makers' Challenge And the Need for Fission Energy

    CERN Document Server

    Nicholson, Martin

    2012-01-01

    The Power Makers - the producers of our electricity - must meet the demands of their customers while also addressing the threat of climate change. There are widely differing views about solutions to electricity generation in an emission constrained world. Some see the problem as relatively straight forward, requiring deep cuts in emissions now by improving energy efficiency, energy conservation and using only renewable resources. Many electricity industry engineers and scientists see the problem as being much more involved.   The Power Makers ’ Challenge: and the need for Fission Energy looks at why using only conventional renewable energy sources is not quite as simple as it seems. Following a general introduction to electricity and its distribution, the author quantifies the reductions needed in greenhouse gas emissions from the power sector in the face of ever increasing world demands for electricity. It provides some much needed background on the many energy sources available for producing electricity ...

  4. q-Gamow States for intermediate energies

    CERN Document Server

    Plastino, A; Zamora, D J

    2016-01-01

    In a recent paper [Nuc. Phys. A {\\bf 948}, (2016) 19] we have demonstrated the possible existence of Tsallis' q-Gamow states. Now, accelerators' experimental evidence for Tsallis' distributions has been ascertained only at very high energies. Here, instead, we develop a different set of q-Gamow states for which the associated q-Breit-Wigner distribution could easily be found at intermediate energies, for which accelerators are available at many locations. In this context, it should be strongly emphasized [Physica A {\\bf 388} (2009) 601] that, empirically, one never exactly and unambiguously "detects" pure Gaussians, but rather q-Gaussians. A prediction is made via Eq.(3.30)

  5. Role of energy cost in the yield of cold ternary fission of 252Cf

    Indian Academy of Sciences (India)

    P V Kunhikrishnan; K P Santhosh

    2013-01-01

    The energy costs in the cold ternary fission of 252Cf for various light charged particle emission are calculated by includingWong's correction for Coulomb potential. Energy cost is found to be higher in cold fission than in normal fission. It is found that energy cost always increases with decrease in experimental yield in all the light charged particle emissions. The higher ground state deformation of the fragments, the odd–even effect and the enhanced yield in the octupole region observed in cold fission are found to be consistent with the concept of energy cost.

  6. Examining fine potential energy effects in high-energy fission dynamics

    Science.gov (United States)

    Mazurek, K.; Schmitt, C.; Nadtochy, P. N.; Kmiecik, M.; Maj, A.; Wasiak, P.; Wieleczko, J. P.

    2013-11-01

    The potential energy surface plays a decisive role in nuclear fission. Together with inertia and viscosity, it influences the trajectory of the system, and the properties of the fission fragments result from the puzzling interplay between static and dynamical effects. A careful study on the influence of the parametrization of the potential energy landscape in heavy-ion-induced fission is performed. Dynamical calculations are done within the stochastic Langevin approach in a three-dimensional deformation space. Various prescriptions of the potential energy surface are considered, probing two different Liquid Drop models and the deformation dependence of the Wigner/congruence energy. A wide set of observables, including cross sections, particle multiplicities, and integral, as well as isotopic and isobaric, distributions of fission and evaporation products, is analyzed. Nuclei close to the Businaro-Gallone point are confirmed to be well suited for investigating the Liquid Drop parametrization, while the influence of the deformation-dependent Wigner/congruence energy is difficult to demonstrate unambiguously in fission at high excitation energies.

  7. Intermediate energy neutron beams from the MURR.

    Science.gov (United States)

    Brugger, R M; Herleth, W H

    1990-01-01

    Several reactors in the United States are potential candidates to deliver beams of intermediate energy neutrons for NCT. At this time, moderators, as compared to filters, appear to be the more effective means of tailoring the flux of these reactors. The objective is to sufficiently reduce the flux of fast neutrons while producing enough intermediate energy neutrons for treatments. At the University of Missouri Research Reactor (MURR), the code MCNP has recently been used to calculate doses in a phantom. First, "ideal" beams of 1, 35, and 1000 eV neutrons were analyzed to determine doses and advantage depths in the phantom. Second, a high quality beam that had been designed to fit in the thermal column of the MURR, was reanalyzed. MCNP calculations of the dose in phantom in this beam confirmed previous calculations and showed that this beam would be a nearly ideal one with neutrons of the desired energy and also a high neutron current. However, installation of this beam will require a significant modification of the thermal column of the MURR. Therefore, a second beam that is less difficult to build and install, but of lower neutron current, has been designed to fit in MURR port F. This beam is designed using inexpensive A1, S, and Pb. The doses calculated in the phantom placed in this beam show that it will be satisfactory for sample tests, animal tests, and possible initial patient trials. Producing this beam will require only modest modifications of the existing tube.

  8. Sustainable, Full-Scope Nuclear Fission Energy at Planetary Scale

    Directory of Open Access Journals (Sweden)

    Robert Petroski

    2012-11-01

    Full Text Available A nuclear fission-based energy system is described that is capable of supplying the energy needs of all of human civilization for a full range of human energy use scenarios, including both very high rates of energy use and strikingly-large amounts of total energy-utilized. To achieve such “planetary scale sustainability”, this nuclear energy system integrates three nascent technologies: uranium extraction from seawater, manifestly safe breeder reactors, and deep borehole disposal of nuclear waste. In addition to these technological components, it also possesses the sociopolitical quality of manifest safety, which involves engineering to a very high degree of safety in a straightforward manner, while concurrently making the safety characteristics of the resulting nuclear systems continually manifest to society as a whole. Near-term aspects of this nuclear system are outlined, and representative parameters given for a system of global scale capable of supplying energy to a planetary population of 10 billion people at a per capita level enjoyed by contemporary Americans, i.e., of a type which might be seen a half-century hence. In addition to being sustainable from a resource standpoint, the described nuclear system is also sustainable with respect to environmental and human health impacts, including those resulting from severe accidents.

  9. q-Gamow states for intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Plastino, A. [La Plata National University and Argentina' s National Research Council, (IFLP-CCT-CONICET)-C. C. 727, 1900 La Plata (Argentina); Rocca, M.C., E-mail: mariocarlosrocca@gmail.com [La Plata National University and Argentina' s National Research Council, (IFLP-CCT-CONICET)-C. C. 727, 1900 La Plata (Argentina); Ferri, G.L. [Fac. de C. Exactas, National University La Pampa, Peru y Uruguay, Santa Rosa, La Pampa (Argentina); Zamora, D.J. [La Plata National University and Argentina' s National Research Council, (IFLP-CCT-CONICET)-C. C. 727, 1900 La Plata (Argentina)

    2016-11-15

    In a recent paper Plastino and Rocca (2016) [18] we have demonstrated the possible existence of Tsallis' q-Gamow states. Now, accelerators' experimental evidence for Tsallis' distributions has been ascertained only at very high energies. Here, instead, we develop a different set of q-Gamow states for which the associated q-Breit–Wigner distribution could easily be found at intermediate energies, for which accelerators are available at many locations. In this context, it should be strongly emphasized Vignat and Plastino (2009) [2] that, empirically, one never exactly and unambiguously “detects” pure Gaussians, but rather q-Gaussians. A prediction is made via Eq. (3.4).

  10. Fission fragment mass energy correlation for 13 actinides ranging from Th to Cf

    Energy Technology Data Exchange (ETDEWEB)

    Caitucoli, F.; Barreau, G.; Leroux, B.; Doan, T.P.; Sicre, A.; Asghar, M.; Perrin, P.; Maurel, M.

    1986-01-01

    Fission fragment mass-energy correlations have been measured for a large range of fissioning systems. The ''cold fragmentations'' mass distributions show the strong influence of the potential energy surface around scission (shell and charge effects).

  11. Dependence of Fission-Fragment Properties On Excitation Energy For Neutron-Rich Actinides

    Directory of Open Access Journals (Sweden)

    Ramos D.

    2016-01-01

    Isotopic fission yields of 250Cf, 244Cm, 240Pu, 239Np and 238U are presented in this work. With this information, the average number of neutrons as a function of the atomic number of the fragments is calculated, which reflects the impact of nuclear structure around Z=50, N=80 on the production of fission fragments. The characteristics of the Super Long, Standard I, Standard II, and Standard III fission channels were extracted from fits of the fragment yields for different ranges of excitation energy. The position and contribution of the fission channels as function of excitation energy are presented.

  12. Fission cross section calculations for 209Bi target nucleus based on fission reaction models in high energy regions

    Directory of Open Access Journals (Sweden)

    Kaplan Abdullah

    2015-01-01

    Full Text Available Implementation of projects of new generation nuclear power plants requires the solving of material science and technological issues in developing of reactor materials. Melts of heavy metals (Pb, Bi and Pb-Bi due to their nuclear and thermophysical properties, are the candidate coolants for fast reactors and accelerator-driven systems (ADS. In this study, α, γ, p, n and 3He induced fission cross section calculations for 209Bi target nucleus at high-energy regions for (α,f, (γ,f, (p,f, (n,f and (3He,f reactions have been investigated using different fission reaction models. Mamdouh Table, Sierk, Rotating Liquid Drop and Fission Path models of theoretical fission barriers of TALYS 1.6 code have been used for the fission cross section calculations. The calculated results have been compared with the experimental data taken from the EXFOR database. TALYS 1.6 Sierk model calculations exhibit generally good agreement with the experimental measurements for all reactions used in this study.

  13. Dynamical aspects of intermediate-energy heavy-ion collisons

    Science.gov (United States)

    Dempsey, James Francis

    1997-10-01

    The production of neutrons, light charged particles (LCPs), and intermediate-mass fragments (IMFs), from the four reactions 55 MeV/A [124,136Xe] + [112,124Sn], is studied with an experimental apparatus which is highly efficient for the detection of both charged particles and neutrons. The IMFs are found more localized in the mid-velocity region (parallel velocity close to center of mass) than are the LPCs, and the detected multiplicity of IMFs depends linearly on the charge lost from the projectile. IMF multiplicity is found to be largely independent of the neutron excess of the system, aside from a slight increase with increasing neutron excess that is expected from statistical-model simulations. Remnants of the projectile, with very little velocity reduction, are found for most of the reaction cross section. Isotopic and isobaric fragment yields in the projectile-velocity region indicate that charge-to- mass ratio neutralization is generally not achieved but is approached when little remains of the projectile. For all systems, the fragments found in the mid-velocity region are substantially more neutron rich than those found in the velocity region dominated by the emission from the projectile. This observation can be qualitatively accounted for if the mid-velocity source (or sources) is either more neutron rich or smaller, with the same neutron-to-proton ratio, than the source with the velocity of the projectile. The observations of this work suggest that the intermediate mass fragments are, to a large extent, formed dynamically by a multiple neck rupture or a proximity-fission type mechanism. Though it remains unexplained, this process enhances the neutron- to-proton ratio of the emitted fragments. This scenario is reminiscent of low-energy ternary fission and one predicted by Boltzmann-Uehling-Uhlenbeck (BUU) calculations. However, these calculations predict too much velocity damping of the projectile remnant and do not produce a mid-velocity neutron

  14. Fission energy program of the U. S. Department of Energy

    Energy Technology Data Exchange (ETDEWEB)

    1978-06-01

    The document describes programs managed by the Program Director for Nuclear Energy, Department of Energy, and under the cognizance of the Committee on Science and Technology, United States House of Representatives. The major portion of the document is concerned with civilian nuclear power development, the policy for which has been established by the National Energy Plan of April 1977, but it also includes descriptions of the space applications and naval reactor programs.

  15. Fission energy program of the U. S. Department of Energy

    Energy Technology Data Exchange (ETDEWEB)

    1978-06-01

    The document describes programs managed by the Program Director for Nuclear Energy, Department of Energy, and under the cognizance of the Committee on Science and Technology, United States House of Representatives. The major portion of the document is concerned with civilian nuclear power development, the policy for which has been established by the National Energy Plan of April 1977, but it also includes descriptions of the space applications and naval reactor programs.

  16. Multi-modal calculations of prompt fission neutrons from 238U(n, f) at low induced energy

    Institute of Scientific and Technical Information of China (English)

    ZHENG Na; ZHONG Chun-Lai; FAN Tie-Shuan

    2011-01-01

    Properties of prompt fission neutrons from 238U(n,f) are calculated for incident neutron energies below 6 MeV using the multi-modal model,including the prompt fission neutron spectrum,the average prompt fission neutron multiplicity,and the prompt fission neutron multiplicity as a function of the fission fragment mass v(A) (usually named “sawtooth” data) The three most dominant fission modes are taken into account.The model parameters are determined on the basis of experimental fission fragment data.The predicted results are in good agreement with the experimental data.

  17. Prompt neutron fission spectrum mean energies for the fissile nuclides and /sup 252/Cf

    Energy Technology Data Exchange (ETDEWEB)

    Holden, N.E.

    1985-01-01

    The international standard for a neutron spectrum is that produced from the spontaneous fission of /sup 252/Cf, while the thermal neutron induced fission neutron spectra for the four fissile nuclides, /sup 233/U, /sup 235/U, /sup 239/Pu, and /sup 241/Pu are of interest from the standpoint of nuclear reactors. The average neutron energies of these spectra are tabulated. The individual measurements are recorded with the neutron energy range measured, the method of detection as well as the average neutron energy for each author. Also tabulated are the measurements of the ratio of mean energies for pairs of fission neutron spectra. 75 refs., 9 tabs. (LEW)

  18. Energy dependence of 238U fission yields investigated in inverse kinematics

    Directory of Open Access Journals (Sweden)

    Veselsky M.

    2010-03-01

    Full Text Available The production cross sections of neutron-rich fission residues produced in reactions induced by a 238U beam impinging onto Pb and Be targets were investigated at the Fragment Separator (FRS at GSI using the inverse kinematic technique. These data allowed us to discuss the optimum energies in fission for producing the most neutron-rich residues.

  19. Fission-like events in the 12C+169Tm system at low excitation energies

    Science.gov (United States)

    Sood, Arshiya; Singh, Pushpendra P.; Sahoo, Rudra N.; Kumar, Pawan; Yadav, Abhishek; Sharma, Vijay R.; Shuaib, Mohd.; Sharma, Manoj K.; Singh, Devendra P.; Gupta, Unnati; Kumar, R.; Aydin, S.; Singh, B. P.; Wollersheim, H. J.; Prasad, R.

    2017-07-01

    Background: Fission has been found to be a dominating mode of deexcitation in heavy-ion induced reactions at high excitation energies. The phenomenon of heavy-ion induced fission has been extensively investigated with highly fissile actinide nuclei, yet there is a dearth of comprehensive understanding of underlying dynamics, particularly in the below actinide region and at low excitation energies. Purpose: Prime objective of this work is to study different aspects of heavy-ion induced fission ensuing from the evolution of composite system formed via complete and/or incomplete fusion in the 12C+169Tm system at low incident energies, i.e., Elab≈6.4 , 6.9, and 7.4 A MeV, as well as to understand charge and mass distributions of fission fragments. Method: The recoil-catcher activation technique followed by offline γ spectroscopy was used to measure production cross sections of fission-like events. The evaporation residues were identified by their characteristic γ rays and vetted by the decay-curve analysis. Charge and mass distributions of fission-like events were studied to obtain dispersion parameters of fission fragments. Results: In the present work, 26 fission-like events (32 ≤Z ≤49 ) were identified at different excitation energies. The mass distribution of fission fragments is found to be broad and symmetric, manifesting their production via compound nuclear processes. The dispersion parameters of fission fragments obtained from the analysis of mass and isotopic yield distributions are found to be in good accord with the reported values obtained for different fissioning systems. A self-consistent approach was employed to determine the isobaric yield distribution. Conclusions: The present work suggests that fission is one of the competing modes of deexcitation of complete and/or incomplete fusion composites at low excitation energies, i.e., E*≈57 , 63, and 69 MeV, where evaporation of light nuclear particle(s) and/or γ rays are assumed to be the sole

  20. Neutron and fission yields from high-energy deuterons in infinite /sup 238/U targets

    Energy Technology Data Exchange (ETDEWEB)

    Canfield, E.

    1965-06-28

    Early work on the interaction of high energy deuterons with large /sup 238/U targets is reexamined and current theoretical study is discussed. Results of fission and neutron yield calculations are compared with experiment. (SDF)

  1. Microscopic description of fission in neutron-rich radium isotopes with the Gogny energy density functional

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Guzman, R. [Kuwait University, Physics Department, Kuwait (Kuwait); Robledo, L.M. [Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain)

    2016-01-15

    Mean-field calculations, based on the D1S, D1N and D1M parametrizations of the Gogny energy density functional, have been carried out to obtain the potential energy surfaces relevant to fission in several Ra isotopes with the neutron number 144 ≤ N ≤ 176. Inner and outer barrier heights as well as first and second isomer excitation energies are given. The existence of a well-developed third minimum along the fission paths of Ra nuclei is analyzed in terms of the energetics of the ''fragments'' defining such elongated configuration. The masses and charges of the fission fragments are studied as functions of the neutron number in the parent Ra isotope. The comparison between fission and α-decay half-lives, reveals that the former becomes faster for increasing neutron numbers. Though there exists a strong variance of the results with respect to the parameters used in the computation of the spontaneous fission rate, a change in tendency is observed at N = 164 with a steady increase that makes heavier neutron-rich Ra isotopes stable against fission, diminishing the importance of fission recycling in the r-process. (orig.)

  2. Laser Intertial Fusion Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, Kevin James [Univ. of California, Berkeley, CA (United States)

    2010-04-08

    This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 μm of tungsten to mitigate x-ray damage. The first wall is cooled by Li17Pb83 eutectic, chosen for its neutron multiplication and good heat transfer properties. The Li17Pb83 flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li17Pb83, separated from the Li17Pb83 by a solid ODS wall. This main system coolant is the molten salt flibe (2LiF-BeF2), chosen for beneficial neutronics and heat transfer properties. The use of flibe enables both fusion fuel production (tritium) and neutron moderation and multiplication for the fission blanket. A Be pebble (1 cm diameter) multiplier layer surrounds the coolant injection plenum and the coolant flows radially through perforated walls across the bed. Outside the Be layer, a fission fuel layer comprised of depleted uranium contained in Tristructural-isotropic (TRISO) fuel particles

  3. Measurements of structural material capture to uranium-235 fission rate ratios in an intermediate spectrum assembly

    Energy Technology Data Exchange (ETDEWEB)

    Azzoni, P.; Benzi, V.; Chiodi, P.L.; Giuliani, C.; Guardini, S.; Marrasi, R.; Salomoni, A.; Tassan, S.

    1980-10-01

    Experimental determinations of capture rates of structural materials used in fast breeder reactors, such as iron, chromium, nickel, and stainless steel, normalized to the /sup 235/U fission rate, were performed. The aim of these experiments was to check structural material multigroup cross-section libraries in the 1- to 100-keV range, where substantial discrepancies among various cross-section evaluations are not yet resolved. The experiments were carried out in an ARGONAUTtype RB-2 reactor, using the Null Reactivity Oscillation method, on test media composed of quasi-homogeneous loose particle mixtures. Comparisons were carried out with corresponding calculated values, showing a trend of these values to overestimate the measured quantities. These results are not in disagreement with the indications of recent /sup 235/U cross-section measurements as far as the sigma /SUB c/ /sigma /SUB f/ of /sup 235/U is concerned.

  4. The dependence of cumulative 238U(n,f) fission yield on incident-neutron energy

    Institute of Scientific and Technical Information of China (English)

    ZHENG Na; ZHONG Chunlai; MA Liyong; CHEN Zhongjing; LI Xiangqing; LIU Tingjin; CHEN Jinxiang; FAN Tieshuan

    2009-01-01

    This work is aim at studying the dependence of fission yields on incident neutron energy,so as to produce evaluated yield sets of the energy dependence.Experimental data at different neutron energies for gas fission products 85m,87,88Kr and 138Xe resulting from the 238U(n,f) reaction are processed using codes AVERAGE for weighed average and ZOTT for simultaneous evaluation.Energy dependence of the cumulative fission product yields on the incident neutron is presented.The evaluated curve of product yield is compared with the results calculated by the TALYS-0.64 code.The present evaluation is consistent with other main libraries in error permission.The fit curve of 87,88Kr can be recommended to predict the unmeasured fission yields.Comparisons of the evaluated energy dependence curves with theoretical calculated results show that the predictions using purely theoretical model for the fission process are not sufficiently accurate and reliable for the calculations of the cumulative fission yields for the 238U(n,f).

  5. Evaluation of excitation energy and spin in fission fragments using the statistical model, and the FIPPS project

    Directory of Open Access Journals (Sweden)

    Sage C.

    2013-03-01

    Full Text Available We review the statistical model and its application for the process of nuclear fission. The expressions for excitation energy and spin distributions for the individual fission fragments are given. We will finally emphasize the importance of measuring prompt gamma decay to further test the statistical model in nuclear fission with the FIPPS project.

  6. Fragment Excitation and Moments of Kinetic Energy Distributions in Nuclear Fission

    Science.gov (United States)

    Faust, Herbert R.

    2004-02-01

    The Random Excitation Model (REX-M) in nuclear fission is formulated with the level density formula from the Fermi-gas model. It is assumed that excitation of fission fragments is totally determined by a temperature calculated from the reaction Q-value. From this assumption fragment excitation, moments of kinetic energy distributions, and neutron evaporation are calculated. It is shown that the measured distributions and the neutron evaporation characteristics are in good agreement with the model calculations. Finally we extend the REX-model to describe aspects of ternary fission.

  7. Nuclear Fission

    Science.gov (United States)

    Denschlag, J. O.

    This chapter first gives a survey on the history of the discovery of nuclear fission. It briefly presents the liquid-drop and shell models and their application to the fission process. The most important quantities accessible to experimental determination such as mass yields, nuclear charge distribution, prompt neutron emission, kinetic energy distribution, ternary fragment yields, angular distributions, and properties of fission isomers are presented as well as the instrumentation and techniques used for their measurement. The contribution concentrates on the fundamental aspects of nuclear fission. The practical aspects of nuclear fission are discussed in http://dx.doi.org/10.1007/978-1-4419-0720-2_57 of Vol. 6.

  8. Fission properties of einsteinium and fermium. [Half-life, kinetic energy release, mass division, prompt neutron emission

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.C.

    1978-01-01

    The systematics of the low energy fission of the fermium isotopes is studied considering half-lives, masss division, kinetic-energy release, and accompanying prompt neutron emission. It is shown that the low energy fission of the fermium isotopes is a microcosm of the fission process, exhibiting a wide range of half lives, mass and kinetic energy distributions and varying neutron emission. The trends in the fermium isotopes are considered. 23 references. (JFP)

  9. Description of Induced Nuclear Fission with Skyrme Energy Functionals: II. Finite Temperature Effects

    CERN Document Server

    Schunck, N; Carr, H

    2013-01-01

    Understanding the mechanisms of induced nuclear fission for a broad range of neutron energies could help resolve fundamental science issues, such as the formation of elements in the universe, but could have also a large impact on societal applications in energy production of nuclear waste management. The goal of this paper is to set up the foundations of a microscopic model to study the static aspects of induced fission as a function of the excitation energy of the incident neutron, from thermal to fast neutrons. To account for the high excitation energy of the compound nucleus, we employ a statistical approach based on finite temperature nuclear density functional theory with Skyrme energy densities, which we benchmark on the fission of 239Pu(n,f). We compute the evolution of the least-energy fission pathway across multidimensional potential energy surfaces with up to five collective variables as a function of the nuclear temperature, and predict the evolution of both the inner and outer fission barriers as ...

  10. DIRECT ENERGY CONVERSION (DEC) FISSION REACTORS - A U.S. NERI PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    D. BELLER; G. POLANSKY; ET AL

    2000-11-01

    The direct conversion of the electrical energy of charged fission fragments was examined early in the nuclear reactor era, and the first theoretical treatment appeared in the literature in 1957. Most of the experiments conducted during the next ten years to investigate fission fragment direct energy conversion (DEC) were for understanding the nature and control of the charged particles. These experiments verified fundamental physics and identified a number of specific problem areas, but also demonstrated a number of technical challenges that limited DEC performance. Because DEC was insufficient for practical applications, by the late 1960s most R&D ceased in the US. Sporadic interest in the concept appears in the literature until this day, but there have been no recent programs to develop the technology. This has changed with the Nuclear Energy Research Initiative that was funded by the U.S. Congress in 1999. Most of the previous concepts were based on a fission electric cell known as a triode, where a central cathode is coated with a thin layer of nuclear fuel. A fission fragment that leaves the cathode with high kinetic energy and a large positive charge is decelerated as it approaches the anode by a charge differential of several million volts, it then deposits its charge in the anode after its kinetic energy is exhausted. Large numbers of low energy electrons leave the cathode with each fission fragment; they are suppressed by negatively biased on grid wires or by magnetic fields. Other concepts include magnetic collimators and quasi-direct magnetohydrodynamic generation (steady flow or pulsed). We present the basic principles of DEC fission reactors, review the previous research, discuss problem areas in detail and identify technological developments of the last 30 years relevant to overcoming these obstacles. A prognosis for future development of direct energy conversion fission reactors will be presented.

  11. The contrasting fission potential-energy structure of actinides and mercury isotopes

    CERN Document Server

    Ichikawa, Takatoshi; Möller, Peter; Sierk, Arnold J

    2012-01-01

    Fission-fragment mass distributions are asymmetric in fission of typical actinide nuclei for nucleon number $A$ in the range $228 \\lnsim A \\lnsim 258$ and proton number $Z$ in the range $90\\lnsim Z \\lnsim 100$. For somewhat lighter systems it has been observed that fission mass distributions are usually symmetric. However, a recent experiment showed that fission of $^{180}$Hg following electron capture on $^{180}$Tl is asymmetric. An earlier experiment has shown fission of $^{198}$Hg and nearby nuclei is symmetric, but with hints of asymmetric yield distributions up to about 10 MeV above the saddle-point energy. We calculate potential-energy surfaces for a typical actinide nucleus and for 12 even isotopes in the range $^{178}$Hg--$^{200}$Hg, demonstrating the radical differences between actinide and mercury potential surfaces. We discuss these differences and how the changing potential-energy structure along the mercury isotope chain affects the observed (a)symmetry of the fission fragments. We show that the ...

  12. Status of art report on intermediate energy nuclear data

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ouk; Chang, Jong Hwa

    1997-06-01

    Nuclear reaction data of intermediate energy ranging above 20 MeV upto a few GeV form an important ingredient of several nuclear energy application, such as medical research, astrophysics, transmutation of radioactive waste and accelerator-driven reactor. Current status of the intermediate energy nuclear data cannot satisfy the requirements of these applications. Despite the fact that theories and models with suitable parameterization and fitting to the experimental data can be used for filling gaps in the available experimental database, current theories and models for intermediate nuclear energy nuclear reaction are still under development. This report summarizes required intermediate energy nuclear data and their physical quantities for the relevant research fields. Theories/models and codes developed up to now for the intermediate nuclear reaction are also outlined and transport codes based on these models are briefly introduced in this report. Available experimental facilities and data libraries are filed and trend of activities in the foreign countries on intermediate energy nuclear data are summarized. It is hoped that this report provide a part of information for the research activity on intermediate energy nuclear data in Korea to establish its long-term plan. (author). 14 tabs., 6 figs

  13. Laser Intertial Fusion Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, Kevin James [Univ. of California, Berkeley, CA (United States)

    2010-04-08

    This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 μm of tungsten to mitigate x-ray damage. The first wall is cooled by Li17Pb83 eutectic, chosen for its neutron multiplication and good heat transfer properties. The Li17Pb83 flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li17Pb83, separated from the Li17Pb83 by a solid ODS wall. This main system coolant is the molten salt flibe (2LiF-BeF2), chosen for beneficial neutronics and heat transfer properties. The use of flibe enables both fusion fuel production (tritium) and neutron moderation and multiplication for the fission blanket. A Be pebble (1 cm diameter) multiplier layer surrounds the coolant injection plenum and the coolant flows radially through perforated walls across the bed. Outside the Be layer, a fission fuel layer comprised of depleted uranium contained in Tristructural-isotropic (TRISO) fuel particles

  14. Metabolism. AMP-activated protein kinase mediates mitochondrial fission in response to energy stress.

    Science.gov (United States)

    Toyama, Erin Quan; Herzig, Sébastien; Courchet, Julien; Lewis, Tommy L; Losón, Oliver C; Hellberg, Kristina; Young, Nathan P; Chen, Hsiuchen; Polleux, Franck; Chan, David C; Shaw, Reuben J

    2016-01-15

    Mitochondria undergo fragmentation in response to electron transport chain (ETC) poisons and mitochondrial DNA-linked disease mutations, yet how these stimuli mechanistically connect to the mitochondrial fission and fusion machinery is poorly understood. We found that the energy-sensing adenosine monophosphate (AMP)-activated protein kinase (AMPK) is genetically required for cells to undergo rapid mitochondrial fragmentation after treatment with ETC inhibitors. Moreover, direct pharmacological activation of AMPK was sufficient to rapidly promote mitochondrial fragmentation even in the absence of mitochondrial stress. A screen for substrates of AMPK identified mitochondrial fission factor (MFF), a mitochondrial outer-membrane receptor for DRP1, the cytoplasmic guanosine triphosphatase that catalyzes mitochondrial fission. Nonphosphorylatable and phosphomimetic alleles of the AMPK sites in MFF revealed that it is a key effector of AMPK-mediated mitochondrial fission.

  15. Dynamical effects in nuclear collisions in the Fermi energy range: aligned breakup of heavy projectiles 24.75.+i; 25.70.Mn; 25.70.Pq; Heavy ions reactions at intermediate energy; Fragment correlations; Fission and aligned breakup; Deformation and neck instability

    CERN Document Server

    Bocage, F; Louvel, M; Auger, G; Bacri, C O; Bellaize, N; Borderie, B; Bougault, R; Brou, R; Buchet, P; Charvet, J L; Chbihi, A; Cussol, D; Dayras, R; De Cesare, N; Demeyer, A N; Doré, D; Durand, D; Frankland, J D; Galíchet, E; Genouin-Duhamel, E; Gerlic, E; Guinet, D; Lautesse, P; Laville, J L; Lecolley, J F; Legrain, R; Le Neindre, N; López, O; Maskay, A M; Nalpas, L; Nguyen, A D; Pârlog, M; Péter, J; Plagnol, E; Rivet, M F; Rosato, E; Saint-Laurent, F; Salou, S; Steckmeyer, J C; Stern, M; Tabacaru, G; Tamain, B; Tirel, O; Tassan-Got, L; Vient, E; Vigilante, M; Volant, C; Wieleczko, J P; Le Brun, C; Genoux-Lubain, A; Rudolf, G; Stuttgé, L

    2000-01-01

    Recent experimental results concerning heavy systems (Pb + Au, Pb + Ag, Pb + Al, Gd + C, Gd + U, Xe + Sn, etc) obtained at GANIL with the INDRA and NAUTILUS 4 pi arrays will be presented. The study of reaction mechanisms has shown the dominant binary and highly dissipative character of the process. The two heavy and excited fragments produced after the first stage of the interaction can decay into various decay modes from evaporation to multifragmentation including fission. However, deviations from this simple picture have been found by analyzing angular and velocity distributions of light charged particles, and fragments. Indeed, there is a certain amount of matter in excess emitted between the two primary sources suggesting either the existence of a mid-rapidity source similar to the one observed in the relativistic regime (participants) or a strong deformation induced by the dynamics of the collision (neck instability). This last possibility has been suggested by analyzing in detail the angular distributio...

  16. Intermediate energy light sources and the SSRF project

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Advances in insertion device technology, top-up operation and superconducting RF cavities make it possible to generate high brightness X-ray with intermediate energy light sources, which leads a new trend in designing and constructing third generation light sources around the world. The development status and the remarkable technical features of intermediate energy light sources are reviewed, and the main SSRF properties are described in this paper.

  17. Fission-fragment energy correlation measurements for /sup 252/Cf(sf) and structures in far-out asymmetric fission

    Energy Technology Data Exchange (ETDEWEB)

    Barreau, G.; Sicre, A.; Caitucoli, F.; Doan, T.P.; Leroux, B.; Martinez, G. (CEA Centre d' Etudes Nucleaires de Bordeaux-Gradignan, 33 - Gradignan (France)); Asghar, M. (Centre d' Etudes Nucleaires, Alger (Algeria)); Benfoughal, T. (CEA Centre d' Etudes Nucleaires de Bordeaux-Gradignan, 33 - Gradignan (France); Centre d' Etudes Nucleaires, Alger (Algeria))

    1985-01-14

    Fragment-mass and kinetic-energy distribution measurements for /sup 252/Cf(sf) have been extended to the far-out asymmetric low-yield fission region of Msub(H) = 190 compared with the existing data that go up to Msub(H) proportional 168. The mass yield Y(m) shows a shoulder for Msub(H) proportional 163 and an important enhancement for Msub(H) > or approx. 176. The (m), sigmasub(EK)(m) and, to a lesser extent, Y(m) distributions show strong and correlated amplitude fluctuations for Msub(H) > or approx. 170. These data indicate strong and rapid changes in deformation of the nascent fragments and the coexistence of more than one deformed-shell stabilized scission configuration for the same mass splits. These structures and those present in the relatively high-yield regions are discussed in terms of the static macro-microscopic potential-energy calculations.

  18. Probing energy dissipation, γ-ray and neutron multiplicity in the thermal neutron-induced fission of {sup 239}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Pahlavani, M.R.; Mirfathi, S.M. [University of Mazandaran, Department of Nuclear Physics, Faculty of Basic Science, Babolsar (Iran, Islamic Republic of)

    2016-04-15

    The incorporation of the four-dimensional Langevin equations led to an integrative description of fission cross-section, fragment mass distribution and the multiplicity and energy distribution of prompt neutrons and γ-rays in the thermal neutron-induced fission of {sup 239}Pu. The dynamical approach presented in this paper thoroughly reproduces several experimental observables of the fission process at low excitation energy. (orig.)

  19. Studies on fission with ALADIN. Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Julie-Fiona; Taieb, Julien; Chatillon, Audrey; Belier, Gilbert; Boutoux, Guillaume; Ebran, Adeline; Gorbinet, Thomas; Grente, Lucie; Laurent, Benoit; Pellereau, Eric [CEA DAM Bruyeres-le-Chatel, Arpajon (France); Alvarez-Pol, Hector; Ayyad, Yassid; Benlliure, Jose; Cortina Gil, Dolores; Caamano, Manuel; Fernandez Dominguez, Beatriz; Paradela, Carlos; Ramos, Diego; Rodriguez-Sanchez, Jose-Luis; Vargas, Jossitt [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Audouin, Laurent; Tassan-Got, Laurent [CNRS/IN2P3, IPNO, Orsay (France); Aumann, Thomas [Technische Universitaet Darmstadt, Darmstadt (Germany); Casarejos, Enrique [Universidad de Vigo, Vigo (Spain); Farget, Fanny; Rodriguez-Tajes, Carme [CNRS/IN2P3, GANIL, Caen (France); Heinz, Andreas [Chalmers University of Technology, Gothenburg (Sweden); Jurado, Beatriz [CNRS/IN2P3, CENBG, Gradignan (France); Kelic-Heil, Aleksandra; Kurz, Nikolaus; Nociforo, Chiara; Pietri, Stephane; Rossi, Dominic; Schmidt, Karl-Heinz; Simon, Haik; Voss, Bernd; Weick, Helmut [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)

    2015-12-15

    A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism. (orig.)

  20. Dynamical effects and fission in the heavy ion collisions at incident energies near the Fermi energy; Effets dynamiques et fission dans les collisions d`ions lourds a des energies incidentes voisines de l`energie de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Jean Colin [Lab. de Physique Corpusculaire, Caen Univ., 14 (France)

    1997-12-01

    In this work we have studied the reaction mechanisms implied in the heavy ion collisions at energies near the Fermi level. We have observed the predominance of binary processes (2 principal nuclei in the exit channel) and selected events leading to the fission of one of the two fragmentation products. On the basis of the study of angular distributions of fission fragments and associated light particles, we have determined the angular momentum of the nucleus in the moment of fission and the angular momentum transfer in the interaction. The comparison of experimental values of the angular momentum transferred with the theoretical models enables the characterization of projectile-target interaction. For the different systems studied, the spin of fissioning nucleus ranges between 30 {Dirac_h} and 60 {Dirac_h} while the transferred angular momentum may reach 90 {Dirac_h}. For these studies the determinant parameter is the sequence of emission of light particles and fragments, hence the lifetime associated to each processes. For central collisions we have measured pre-fission lifetimes lower then 10{sup -21} sec. These values are very short in comparison with the statistical fission processes, what prompted to search for off-equilibrium (non-statistical) phenomena in the data. Taking into account the charges of the fission fragments we were able to isolate a dynamical component and a statistical component in the fission process. We have compared these two classes of events and showed that there is a relative excess of energy between the fragments when the origin of scission is dynamical. We hope to derive of this observable the nuclear deformation velocity and constrain the value of the nuclear matter viscosity in comparison with the theoretical models 54 refs., 27 figs., 2 tabs.

  1. Microscopic description of fission in neutron-rich Radium isotopes with the Gogny energy density functional

    CERN Document Server

    Rodriguez-Guzman, R R

    2015-01-01

    Mean field calculations, based on the D1S, D1N and D1M parametrizations of the Gogny energy density functional, have been carried out to obtain the potential energy surfaces relevant to fission in several Ra isotopes with the neutron number 144 $\\le$ N $\\le$ 176. Inner and outer barrier heights as well as first and second isomer excitation energies are given. The existence of a well developed third minimum along the fission paths of Ra nuclei, is analyzed in terms of the energetics of the "fragments" defining such elongated configuration. The masses and charges of the fission fragments are studied as functions of the neutron number in the parent Ra isotope. The comparison between fission and $\\alpha$-decay half-lives, reveals that the former becomes faster for increasing neutron numbers. Though there exists a strong variance of the results with respect to the parameters used in the computation of the spontaneous fission rate, a change in tendency is observed at N=164 with a steady increase that makes heavier ...

  2. Improved fission neutron energy discrimination with 4He detectors through pulse filtering

    Science.gov (United States)

    Zhu, Ting; Liang, Yinong; Rolison, Lucas; Barker, Cathleen; Lewis, Jason; Gokhale, Sasmit; Chandra, Rico; Kiff, Scott; Chung, Heejun; Ray, Heather; Baciak, James E.; Enqvist, Andreas; Jordan, Kelly A.

    2017-03-01

    This paper presents experimental and computational techniques implemented for 4He gas scintillation detectors for induced fission neutron detection. Fission neutrons are produced when natural uranium samples are actively interrogated by 2.45 MeV deuterium-deuterium fusion reaction neutrons. Fission neutrons of energies greater than 2.45 MeV can be distinguished by their different scintillation pulse height spectra since 4He detectors retain incident fast neutron energy information. To enable the preferential detection of fast neutrons up to 10 MeV and suppress low-energy event counts, the detector photomultiplier gain is lowered and trigger threshold is increased. Pile-up and other unreliable events due to the interrogating neutron flux and background radiation are filtered out prior to the evaluation of pulse height spectra. With these problem-specific calibrations and data processing, the 4He detector's accuracy at discriminating fission neutrons up to 10 MeV is improved and verified with 252Cf spontaneous fission neutrons. Given the 4He detector's ability to differentiate fast neutron sources, this proof-of-concept active-interrogation measurement demonstrates the potential of special nuclear materials detection using a 4He fast neutron detection system.

  3. Decay heat and anti-neutrino energy spectra in fission fragments from total absorption spectroscopy

    Science.gov (United States)

    Rykaczewski, Krzysztof

    2015-10-01

    Decay studies of over forty 238U fission products have been studied using ORNL's Modular Total Absorption Spectrometer. The results are showing increased decay heat values, by 10% to 50%, and the energy spectra of anti-neutrinos shifted towards lower energies. The latter effect is resulting in a reduced number of anti-neutrinos interacting with matter, often by tens of percent per fission product. The results for several studied nuclei will be presented and their impact on decay heat pattern in power reactors and reactor anti-neutrino physics will be discussed.

  4. Fission fragment charge and mass distributions in 239Pu(n,f) in the adiabatic nuclear energy density functional theory

    CERN Document Server

    Regnier, D; Schunck, N; Verriere, M

    2016-01-01

    Accurate knowledge of fission fragment yields is an essential ingredient of numerous applications ranging from the formation of elements in the r-process to fuel cycle optimization for nuclear energy. The need for a predictive theory applicable where no data is available is an incentive to develop a fully microscopic approach to fission dynamics. In this work, we calculate the pre-neutron emission charge and mass distributions of the fission fragments formed in the neutron-induced fission of 239Pu using a microscopic method based on nuclear energy density functional (EDF) method, where large amplitude collective motion is treated adiabatically using the time dependent generator coordinate method (TDGCM) under the Gaussian overlap approximation (GOA). Fission fragment distributions are extracted from the flux of the collective wave packet through the scission line. We find that the main characteristics of the fission charge and mass distributions can be well reproduced by existing energy functionals even in tw...

  5. Odd–even effect in fragment angular momentum in low-energy fission of actinides

    Indian Academy of Sciences (India)

    B S Tomar; R Tripathi; A Goswami

    2007-01-01

    Quantitative explanation for the odd–even effect on fragment angular momenta in the low-energy fission of actinides have been provided by taking into account the single particle spin of the odd proton at the fragment's scission point deformation in the case of odd- fragments along with the contribution from the population of angular momentum bearing collective vibrations of the fissioning nucleus at scission point. The calculated fragment angular momenta have been found to be in very good agreement with the experimental data for fragments in the mass number region of 130–140. The odd–even effect observed in the fragment angular momenta in the low-energy fission of actinides has been explained quantitatively for the first time.

  6. Collective spectra along the fission barrier

    Directory of Open Access Journals (Sweden)

    Pigni M. T.

    2012-12-01

    Full Text Available Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states and in the intermediate wells (superdeformed and hyperdeformed states play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two–cluster configurations in a dynamical way, permitting exchange of upper–shell nucleons between clusters. The impact of theoretical spectra on neutron–induced fission cross sections and, in combination with an improved version of the scission–point model, on angular distribution of fission fragments is evaluated for plutonium isotopes of interest to nuclear energy applications.

  7. Excitation Functions of Fusion and Fission for 32S+170Er at Energies Near and Below Coulomb Barrier

    Institute of Scientific and Technical Information of China (English)

    BAO; Peng-fei; LIN; Cheng-jian; YANG; Feng; JIA; Hui-ming; XU; Xin-xing; YANG; Lei; SUN; Li-jie; MA; Nan-ru; ZHANG; Huan-qiao; LIU; Zu-hua

    2013-01-01

    Excitation functions of fusion evaporation residue(ER)and fission for 32S+170Er system at near barrier energy region were measured,respectively.With the comparison to the calculations of coupledchannels effects,it is accessible to investigate the impacts on the fusion and fission processes of target deformation and the dependence on the entrance-channel.The experiment was performed at Beijing HI-13 Tandem Accelerator.Fission and fusion evaporation

  8. Yield-Energy Evaluation of 85Kr of 239Pu+n Fission

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The yields of 85Kr, the important production of the 239Pu fission, were re-evaluated over the incident neutron energy 1-15 MeV, based upon all the experimental data. The yields as function of energ

  9. Effects of Fission Yield Data in the Calculation of Antineutrino Spectra for 235U (n ,fission) at Thermal and Fast Neutron Energies

    Science.gov (United States)

    Sonzogni, A. A.; McCutchan, E. A.; Johnson, T. D.; Dimitriou, P.

    2016-04-01

    Fission yields form an integral part of the prediction of antineutrino spectra generated by nuclear reactors, but little attention has been paid to the quality and reliability of the data used in current calculations. Following a critical review of the thermal and fast ENDF/B-VII.1 235U 235 fission yields, deficiencies are identified and improved yields are obtained, based on corrections of erroneous yields, consistency between decay and fission yield data, and updated isomeric ratios. These corrected yields are used to calculate antineutrino spectra using the summation method. An anomalous value for the thermal fission yield of 86Ge generates an excess of antineutrinos at 5-7 MeV, a feature which is no longer present when the corrected yields are used. Thermal spectra calculated with two distinct fission yield libraries (corrected ENDF/B and JEFF) differ by up to 6% in the 0-7 MeV energy window, allowing for a basic estimate of the uncertainty involved in the fission yield component of summation calculations. Finally, the fast neutron antineutrino spectrum is calculated, which at the moment can only be obtained with the summation method and may be relevant for short baseline reactor experiments using highly enriched uranium fuel.

  10. Effects of Fission Yield Data in the Calculation of Antineutrino Spectra for ^{235}U(n,fission) at Thermal and Fast Neutron Energies.

    Science.gov (United States)

    Sonzogni, A A; McCutchan, E A; Johnson, T D; Dimitriou, P

    2016-04-01

    Fission yields form an integral part of the prediction of antineutrino spectra generated by nuclear reactors, but little attention has been paid to the quality and reliability of the data used in current calculations. Following a critical review of the thermal and fast ENDF/B-VII.1 ^{235}U fission yields, deficiencies are identified and improved yields are obtained, based on corrections of erroneous yields, consistency between decay and fission yield data, and updated isomeric ratios. These corrected yields are used to calculate antineutrino spectra using the summation method. An anomalous value for the thermal fission yield of ^{86}Ge generates an excess of antineutrinos at 5-7 MeV, a feature which is no longer present when the corrected yields are used. Thermal spectra calculated with two distinct fission yield libraries (corrected ENDF/B and JEFF) differ by up to 6% in the 0-7 MeV energy window, allowing for a basic estimate of the uncertainty involved in the fission yield component of summation calculations. Finally, the fast neutron antineutrino spectrum is calculated, which at the moment can only be obtained with the summation method and may be relevant for short baseline reactor experiments using highly enriched uranium fuel.

  11. Role of effective distance in the fission mechanism study by the double-energy measurement for uranium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Hiroshi; Saito, Tadashi; Takahashi, Naruto [Osaka Univ., Suita (Japan)] [and others

    1997-09-01

    Fission product kinetic energies were measured by the double-energy method for thermal-neutron fission of {sup 235,233}U and proton-induced fission of {sup 238}U at the 15.8-MeV excitation. From the obtained energy-mass correlation data, the kinetic-energy distribution was constructed from each mass bin to evaluate the first moment of the kinetic energy for a given fragment mass. The resulting kinetic energy was then converted to the effective distance between the charge centers at the moment of scission. The effective distances deduced for the proton-induced fission was concluded to be classified into two constant values, one for asymmetric and the other for symmetric mode, irrespective of the mass though an additional component was further extracted in the asymmetric mass region. This indicates that the fission takes place via two well-defined saddles, followed by the random neck rupture. On the contrary, the effective distances obtained for thermal-neutron induced fission turned out to lie along the contour line at the same level as the equilibrium deformation in the two-dimensional potential map. This strongly suggests that it is essentially a barrier-penetrating type of fission rather than the over-barrier fission. (author). 73 refs.

  12. A new facility for high-energy neutron-induced fission studies

    Energy Technology Data Exchange (ETDEWEB)

    Prokofiev, A.V. [The Svedberg Lab., Uppsala Univ., Uppsala (Sweden)]|[V.G. Khlopin Radium Inst., St. Petersburg (Russian Federation); Pomp, S.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Mermod, P.; Oesterlund, M.; Blomgren, J. [Dept. of Neutron Research, Uppsala Univ., Uppsala (Sweden); Tippawan, U. [Dept. of Neutron Research, Uppsala Univ., Uppsala (Sweden)]|[Fast Neutron Research Facility, Chiang Mai Univ., Chiang Mai (Thailand); Dangtip, S. [Fast Neutron Research Facility, Chiang Mai Univ., Chiang Mai (Thailand); Einarsson, L. [The Svedberg Lab., Uppsala Univ., Uppsala (Sweden); Gavrikov, Yu.A.; Kotov, A.A.; Vaishnene, L.A. [Petersburg Nuclear Physics Inst., Gatchina, Leningrad District (Russian Federation); Germann, T. [Univ. of Konstanz, Konstanz (Germany)

    2003-07-01

    A new facility is constructed for measurements of neutron-induced fission cross-sections in the 20-180 MeV energy region versus the np scattering cross-section, which is adopted as the primary neutron standard. The advantage of the experiment compared to earlier studies is that the fission-fragment detection and the neutron-flux measurement via np scattering are performed simultaneously and at the same position in the beam, and, therefore, many sources of systematic errors cancel out. Further reduction of systematic errors is achieved due to ''embedded'' determination of effective solid angle of particle detectors using {alpha}-particles from the radioactive decay of the target nuclei. The performance of the facility is illustrated by first data obtained for angular distributions of fission fragments in the {sup 238}U(n,f) reaction. (orig.)

  13. Isotope analysis in central heavy ion collisions at intermediate energies

    Science.gov (United States)

    Geraci, E.; Abbondanno, U.; Bardelli, L.; Barlini, S.; Bini, M.; Bruno, M.; Cannata, F.; Casini, G.; Chiari, M.; D'Agostino, M.; de Sanctis, J.; Giussani, A.; Gramegna, F.; Kravchuk, V. L.; Lanchais, A. L.; Marini, P.; Moroni, A.; Nannini, A.; Olmi, A.; Ordine, A.; Pasquali, G.; Piantelli, S.; Poggi, G.; Vannini, G.; Nucl-Ex Collaboration

    2007-11-01

    Symmetry energy is a key quantity in the study of the equation of state of asymmetric nuclear matter. Heavy ion collisions at low and intermediate energies, performed at Laboratori Nazionali di Legnaro and Laboratori Nazionali del Sud, can be used to extract information on the symmetry energy coefficient Csym, which is currently poorly known but relevant both for astrophysics and for deeper knowledge of the structure of exotic nuclei.

  14. Isotope analysis in central heavy ion collisions at intermediate energies

    CERN Document Server

    Geraci, E; Bardelli, L; Barlini, S; Bini, M; Bruno, M; Cannata, F; Casini, G; Chiari, M; D'Agostino, M; De Sanctis, J; Giussani, A; Gramegna, F; Kravchuk, V L; Lanchais, A L; Marini, P; Moroni, A; Nannini, A; Olmi, A; Ordine, A; Pasquali, G; Piantelli, S; Poggi, G; Vannini, G

    2006-01-01

    Symmetry energy is a key quantity in the study of the equation of state of asymmetric nuclear matter. Heavy ion collisions at low and intermediate energies, performed at Laboratori Nazionali di Legnaro and Laboratori Nazionali del Sud, can be used to extract information on the symmetry energy coefficient Csym, which is currently poorly known but relevant both for astrophysics and for structure of exotic nuclei.

  15. Fission excitation function for 19F + 194,196,198Pt at near and above barrier energies

    Directory of Open Access Journals (Sweden)

    Singh Varinderjit

    2015-01-01

    Full Text Available Fission excitation functions for 19F + 194,196,198Pt reactions populating 213,215,217Fr compound nuclei are reported. Out of these three compound nuclei, 213Fr is a shell closed (N=126 compound nucleus and the other two are away from the shell closure. From a comparison of the experimental fission cross-sections with the statistical model predictions, it is observed that the fission cross-sections are underestimated by the statistical model predictions using shell corrected finite range rotating liquid drop model (FRLDM fission barriers. Further the FRLDM fission barriers are reduced to fit the fission cross-sections over the entire measured energy range.

  16. Feasibility of Traveling Wave Direct Energy Conversion of Fission Reaction Fragments

    Science.gov (United States)

    Tarditi, A. G.; George, J. A.; Miley, G. H.; Scott, J. H.

    2013-01-01

    Fission fragment direct energy conversion has been considered in the past for the purpose of increasing nuclear power plant efficiency and for advanced space propulsion. Since the fragments carry electric charge (typically in the order of 20 e) and have 100 MeV-range kinetic energy, techniques utilizing very high-voltage DC electrodes have been considered. This study is focused on a different approach: the kinetic energy of the charged fission fragments is converted into alternating current by means of a traveling wave coupling scheme (Traveling Wave Direct Energy Converter, TWDEC), thereby not requiring the utilization of high voltage technology. A preliminary feasibility analysis of the concept is introduced based on a conceptual level study and on a particle simulation model of the beam dynamics.

  17. Fission cross sections of sup 2 sup 0 sup 9 Bi, sup 2 sup 3 sup 2 Th, sup 2 sup 3 sup 5 U, sup 2 sup 3 sup 8 U and sup 2 sup 3 sup 7 Np by intermediate energy protons and deuterons

    CERN Document Server

    Yurevich, V I; Nikilaev, V A; Yakovlev, R M

    2002-01-01

    Fission cross sections of sup 2 sup 0 sup 9 Bi, sup 2 sup 3 sup 2 Th, sup 2 sup 3 sup 5 U, sup 2 sup 3 sup 8 U, and sup 2 sup 3 sup 7 Np have been measured with 1.0-3.7-GeV protons and 1.0-GeV deuterons. The results are compared with other experimental data, available evaluations, and predictions of the theoretical model

  18. Neutrino interactions with nucleons and nuclei at intermediate energies

    CERN Document Server

    Alvarez-Ruso, L; Mosel, U

    2006-01-01

    We investigate neutrino-nucleus collisions at intermediate energies incorporating quasielastic scattering and Delta(1232) excitation as elementary processes, together with Fermi motion, Pauli blocking and mean-field potentials in the nuclear medium. A full coupled-channel treatment of final state interactions is achieved with a semiclassical BUU transport model. Results for inclusive reactions and nucleon knockout are presented.

  19. Experimental Studies of Few-nucleon Systems at Intermediate Energies

    NARCIS (Netherlands)

    Stephan, E.; Kistryn, St.; Kalantar-Nayestanaki, N.

    2014-01-01

    Systems composed of 3 nucleons are a subject of precise experimental studies for many years. At the first stage the investigations were mainly focused on elastic nucleon-deuteron scattering, slowly extending to systematic measurements of the deuteron breakup reaction. Intermediate energies, below th

  20. The Fukushima nuclear disaster and its effects on media framing of fission and fusion energy technologies

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Luisa; Horta, Ana; Pereira, Sergio; Delicado, Ana [Institute of Social Sciences of the University of Lisbon, Av. Prof. Anibal de Bettencourt, 9 1600-189 Lisbon (Portugal)

    2015-07-01

    This paper presents results of a comparison of media coverage of fusion and fission energy technologies in three countries (Germany, Spain and Portugal) and in the English language international print media addressing transnational elite, from 2008 to 2012. The analysis showed that the accident in Fukushima in March 2010 did not have significant impact on media framing of nuclear fusion in the major part of print media under investigation. In fact, fusion is clearly dissociated from traditional nuclear (fission) energy and from nuclear accidents. It tends to be portrayed as a safe, clean and unlimited source of energy, although less credited when confronted with research costs, technological feasibility and the possibility to be achieved in a reasonable period of time. On the contrary, fission is portrayed as a hazardous source of energy, expensive when compared to research costs of renewables, hardly a long-term energy option, susceptible to contribute to the proliferation of nuclear weapons or rogue military use. Fukushima accident was consistently discussed in the context of safety problems of nuclear power plants and in many cases appeared not as an isolated event but rather as a reminder of previous nuclear disasters such as Three Miles Island and Chernobyl. (authors)

  1. Fifty years of nuclear fission: Nuclear data and measurements series

    Energy Technology Data Exchange (ETDEWEB)

    Lynn, J.E.

    1989-06-01

    This report is the written version of a colloquium first presented at Argonne National Laboratory in January 1989. The paper begins with an historical preamble about the events leading to the discovery of nuclear fission. This leads naturally to an account of early results and understanding of the fission phenomena. Some of the key concepts in the development of fission theory are then discussed. The main theme of this discussion is the topography of the fission barrier, in which the interplay of the liquid-drop model and nucleon shell effects lead to a wide range of fascinating phenomena encompassing metastable isomers, intermediate-structure effects in fission cross-sections, and large changes in fission product properties. It is shown how study of these changing effects and theoretical calculations of the potential energy of the deformed nucleus have led to broad qualitative understanding of the nature of the fission process. 54 refs., 35 figs.

  2. Mass yields and kinetic energy of fragments from fission of highly-excited nuclei with A≲220

    Science.gov (United States)

    Denisov, V. Yu.; Margitych, T. O.; Sedykh, I. Yu.

    2017-02-01

    It is shown that the potential energy surface of the two separated fragments has the saddle point, which takes place at small distance between the surfaces of well-deformed fragments. The height of this two-body saddle point is larger than the height of one-body fission barrier for nuclei with A ≲ 220. The mass yields of the fission fragments, which are appearing at the fission of nuclei with A ≲ 220, are related to the number of states of the two-fragment systems at the two-body saddle points. The characteristics of kinetic energy of fragments are described by using the trajectory motion equations with the dissipation terms. The Gaussian distribution of the final kinetic energy around the classical value of this energy induced by the stochastic fluctuations is taken into account at an evaluation of the total kinetic energy distributions of the fission fragments.

  3. Total kinetic energy release in the fast neutron-induced fission of $^{235}$U

    CERN Document Server

    Yanez, R; King, J; Barrett, J S; Fotiades, N; Lee, H Y

    2015-01-01

    We have measured the total kinetic energy (TKE) release for the $^{235}$U(n,f) reaction for $E_{n}$=2-100 MeV using the 2E method with an array of Si PIN diode detectors. The neutron energies were determined by time of flight measurements using the white spectrum neutron beam at the LANSCE facility. (To calibrate the apparatus, the TKE release for $^{235}$U(n$_{th}$,f) was also measured using a thermal neutron beam from the OSU TRIGA reactor). The TKE decreases non-linearly from 169.0 MeV to 161.4 MeV for $E_{n}$=2-90 MeV. The standard deviation of the TKE distribution is constant from $E_{n}$=20-90 MeV. Comparison of the data with the multi-modal fission model of Brosa indicates the TKE decrease is a consequence of the growth of symmetric fission and the corresponding decrease of asymmetric fission with increasing neutron energy. The average TKE associated with the Brosa superlong, standard I and standard II modes for a given mass is independent of neutron energy.

  4. Systems Modeling For The Laser Fusion-Fission Energy (LIFE) Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Meier, W R; Abbott, R; Beach, R; Blink, J; Caird, J; Erlandson, A; Farmer, J; Halsey, W; Ladran, T; Latkowski, J; MacIntyre, A; Miles, R; Storm, E

    2008-10-02

    A systems model has been developed for the Laser Inertial Fusion-Fission Energy (LIFE) power plant. It combines cost-performance scaling models for the major subsystems of the plant including the laser, inertial fusion target factory, engine (i.e., the chamber including the fission and tritium breeding blankets), energy conversion systems and balance of plant. The LIFE plant model is being used to evaluate design trade-offs and to identify high-leverage R&D. At this point, we are focused more on doing self consistent design trades and optimization as opposed to trying to predict a cost of electricity with a high degree of certainty. Key results show the advantage of large scale (>1000 MWe) plants and the importance of minimizing the cost of diodes and balance of plant cost.

  5. Measurement of the energy spectra of fission fragments using nuclear track detectors and digital image processing

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, Guillermo; Golzarri, Jose I. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, Mexico D.F. 01000 (Mexico); Castano, Victor M., E-mail: castano@fata.unam.m [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Boulevard Juriquilla 3001, Santiago de Queretaro, Queretaro 76230 (Mexico)

    2010-08-15

    Energy spectra of fission fragments were determined using a Nuclear Track Methodology (NTM) supported by digital image analysis and numerical data processing using a standard personal computer. The analysis of a californium ({sup 252}Cf) spectrum with this approach shows improvement compared with the values reported previously using the standard procedure, in terms of resolution and accuracy. This new method adds full automation to the technical advantages and cost effectiveness of an NTM.

  6. Study of Relationship Between Neutron Energy and Fission Yields of 95Zr, 140Ba and 147Nd From 235U

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This work measures fission yields of 235U induced by neutrons with energy of thermal, 3.0, 5.0, 5.5, 8.0 and 14.8 MeV. The main purpose is to study the relationship between neutron energy and fission fields of 95Zr,140Ba and 147Nd from 235U by measuring the radioactivity of foil with direct gamma spectrometry. The fission yields induced by fast neutrons are get by fast-thermal-ratio method which based on yields from thermal neutrons, yields by thermal neutron are come from absolute measurement. Since fast-thermal-ratio method eliminates uncertainties of gamma intensity, gamma

  7. Energy and Mass Distributions of Induced-Fission of 197 Au Nucleus by 29 MeV Protons

    Institute of Scientific and Technical Information of China (English)

    S.Soheyli

    2007-01-01

    A thin target of197 Au is bombarded with 29 MeV protons from the cyclotron at Department of Nuclear Research Centre for Agriculture and Medicine. Correlated energies of fission-fragment pairs are measured with silicon surface-barrier detectors and their time of flights is made using a spectrometry pair. The fission cross section, fragment mass distribution, and total kinetic energy distribution of the fission fragments are measured in our experiment. The results are also compared with the previous works and good agreements are found.

  8. Total kinetic energy release in the fast neutron-induced fission of $^{235}$U

    CERN Document Server

    Yanez, R; King, J; Barrett, J S; Fotiades, N; Lee, H Y

    2016-01-01

    We have measured the total kinetic energy (TKE) release for the $^{235}$U(n,f) reaction for $E_{n}$=2-100 MeV using the 2E method with an array of Si PIN diode detectors. The neutron energies were determined by time of flight measurements using the white spectrum neutron beam at the LANSCE facility. To benchmark the TKE measurement, the TKE release for $^{235}$U(n$_{th}$,f) was also measured using a thermal neutron beam from the Oregon State University TRIGA reactor, giving pre-neutron emission $E^*_{TKE}=170.7\\pm0.4$ MeV in good agreement with known values. Our measurements are thus absolute measurements. The TKE in $^{235}$U(n,f) decreases non-linearly from 169.0 MeV to 161.4 MeV for $E_{n}$=2-90 MeV. Comparison of the data with the multi-modal fission model of Brosa indicates the TKE decrease is a consequence of the growth of symmetric fission and the corresponding decrease of asymmetric fission with increasing neutron energy. The average TKE associated with the Brosa superlong, standard I and standard II ...

  9. Measurements of charge distributions of the fragments in the low energy fission reaction

    Science.gov (United States)

    Wang, Taofeng; Han, Hongyin; Meng, Qinghua; Wang, Liming; Zhu, Liping; Xia, Haihong

    2013-01-01

    The measurement for charge distributions of fragments in spontaneous fission 252Cf has been performed by using a unique style of detector setup consisting of a typical grid ionization chamber and a ΔΕ-Ε particle telescope, in which a thin grid ionization chamber served as the ΔΕ-section and the E-section was an Au-Si surface barrier detector. The typical physical quantities of fragments, such as mass number and kinetic energies as well as the deposition in the gas ΔΕ detector and E detector were derived from the coincident measurement data. The charge distributions of the light fragments for the fixed mass number A2* and total kinetic energy (TKE) were obtained by the least-squares fits for the response functions of the ΔΕ detector with multi-Gaussian functions representing the different elements. The results of the charge distributions for some typical fragments are shown in this article which indicates that this detection setup has the charge distribution capability of Ζ:ΔΖ>40:1. The experimental method developed in this work for determining the charge distributions of fragments is expected to be employed in the neutron induced fissions of 232Th and 238U or other low energy fission reactions.

  10. Transport code and nuclear data in intermediate energy region

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Akira; Odama, Naomitsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Maekawa, F.; Ueki, K.; Kosaka, K.; Oyama, Y.

    1998-11-01

    We briefly reviewed the problems of intermediate energy nuclear data file and transport codes in connection with processing of the data. This is a summary of our group in the task force on JENDL High Energy File Integral Evaluation (JHEFIE). In this article we stress the necessity of the production of intermediate evaluated nuclear data file up to 3 GeV for the application of accelerator driven transmutation (ADT) system. And also we state the necessity of having our own transport code system to calculate the radiation fields using these evaluated files from the strategic points of view to keep our development of the ADT technology completely free from other conditions outside of our own such as imported codes and data with poor maintenance or unknown accuracy. (author)

  11. Fission-product energy release for times following thermal-neutron fission of /sup 235/U between 2 and 14000 seconds

    Energy Technology Data Exchange (ETDEWEB)

    Dickens, J.K.; Emery, J.F.; Love, T.A.; McConnell, J.W.; Northcutt, K.J.; Peelle, R.W.; Weaver, H.

    1977-10-01

    Fission-product decay energy-releases rates were measured for thermal-neutron fission of /sup 235/U. Samples of mass 1 to 10 ..mu..g were irradiated for 1 to 100 sec by use of the fast pneumatic-tube facility at the Oak Ridge Research Reactor. The resulting beta- and gamma-ray emissions were counted for times-after-fission between 2 and 14,000 seconds. The data were obtained for beta and gamma rays separately as spectral distributions, N(E/sub ..gamma../) vs E/sub ..gamma../ and N(E/sub beta/) vs E/sub ..beta../. For the gamma-ray data the spectra were obtained by using a NaI detector, while for the beta-ray data the spectra were obtained by using an NE-110 detector with an anticoincidence mantle. The raw data were unfolded to provide spectral distributions of modest resolution. These were integrated over E/sub ..gamma../ and E/sub ..beta../ to provide total yield and energy integrals as a function of time after fission. Results are low compared to the present 1973 ANS Decay-heat standard. A complete description of the experimental apparatus and data-reduction techniques is presented. The final integral data are given in tabular and graphical form and are compared with published data. 41 figures, 13 tables.

  12. Chimera microscopic approach to heavy ion collisions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Lukasik, J.; Majka, Z. [Uniwersytet Jagiellonski, Cracow (Poland). Inst. Fizyki

    1993-12-01

    A microscopic model based on a molecular dynamics concept is presented. The model simulates some quantum effects and thus enables studies of large fermionic systems. It was devised to investigate the dynamics of heavy ion collision at intermediate energies. The model was applied to study an early phase of the {sup 84}Kr+{sup 159}Tb reaction at 45 MeV/nucleon. (author). 30 refs, 9 figs.

  13. Total fission cross section of {sup 181}Ta and {sup 208}Pb induced by protons at relativistic energies

    Energy Technology Data Exchange (ETDEWEB)

    Ayyad, Y.; Benlliure, J.; Casarejos, E. [Group GENP, Dpto. Fisica de Particulas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Schmidt, K. H. [GSI, Planckstrasse 1, 64941, Darmstadt (Germany); Jurado, B. [Universite Bordeaux I, CNRS/IN2 P3, CENBG, BP 120, F-33175 Gradignan (France); Kelic-Heil, A. [GSI, Planckstrasse 1, 64941, Darmstadt (Germany); Pol, H. A. [Group GENP, Dpto. Fisica de Particulas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Ricciardi, M. V.; Pleskac, R. [GSI, Planckstrasse 1, 64941, Darmstadt (Germany); Enqvist, T. [CUPP Project, P.O. Box 22, FI-86801, Pyhsalmi (Finland); Rejmund, F. [Grand Accelerateur National D Ions Lourds, BP 55027, F-14076 Caen Cedex 05 (France); Giot, L. [Subatech - Ecole des Mines de Nantes (France); Henzl, V. [Massachusetts Inst. of Technology, 77, Massachusetts Ave, Cambridge, MA 02139 (United States); Lukic, S. [Karlsruhe Inst. of Technology, D-76021 Karlsruhe (Germany); Ngoc, S. N. [Dept. of Nuclear Physics, Inst. of Physics, National Centre for Natural Science and Technology, NgiaDo-TuLiem, Hanoi (Viet Nam); Boudard, A. [DSM/IRFU/CEA, 91191 Gif-sur-Ivette (France); Universite Louis Pasteur, Strasbourg (France); Leray, S. [DSM/IRFU/CEA, 91191 Gif-sur-Ivette (France); Fernandez, M. [Entro de Investigaciones Energticas Medioambientales Y Tecnolgicas, Madrid (Spain); Kurtukian, T. [Universite Bordeaux I, CNRS/IN2 P3, CENBG, BP 120, F-33175 Gradignan (France); Nadtochy, P. [Omsk State Univ., Dept. of Theoretical Physics, RU-644077 Omsk (Russian Federation); Schmitt, C. [Grand Accelerateur National D' Ions Lourds, BP 55027, F-14076 Caen Cedex 05 (France); Henzlova, D. [Los Alamos National Laboratory, Safeguards Science and Technology Group N-1, Los Alamos, NM 87545 (United States); Paradela, C. [Group GENP, Dpto. Fisica de Particulas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Bacquias, A. [DSM/IRFU/CEA, 91191 Gif-sur-Ivette (France); Universite Louis Pasteur, Strasbourg (France); Loureiro, D. P. [Group GENP, Dpto. Fisica de Particulas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Foehr, V. [GSI, Planckstrasse 1, 64941, Darmstadt (Germany); Tarrio, D. [Group GENP, Dpto. Fisica de Particulas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Kezzar, K. [DSM/IRFU/CEA, 91191 Gif-sur-Ivette (France)

    2011-07-01

    Total fission cross section induced by protons in {sup 181}Ta and {sup 208}Pb at energies in the range of 300 to 1000 A MeV have been measured at GSI (Germany) using the inverse kinematics technique. A dedicated setup with high efficiency made it possible to determine these cross sections with high accuracy. The new data seed light in the controversial results obtained so far and contribute to the understanding of the fission process at high excitation energies. (authors)

  14. Strange particle production at low and intermediate energies

    CERN Document Server

    Alam, M Rafi; Athar, M Sajjad; Vacas, M J Vicente

    2011-01-01

    The weak kaon production off the nucleon induced by neutrinos and antineutrinos is studied at low and intermediate energies of interest for some ongoing and future neutrino oscillation experiments. We develop a microscopical model based on the SU(3) chiral Lagrangians. The studied mechanisms are the main source of kaon production for neutrino energies up to 2 GeV for the various channels and the cross sections are large enough to be amenable to be measured by experiments such as Minerva, T2K and NO$\

  15. Parameters of the Disk Loaded Waveguide structure for intermediate particles acceleration in the intermediate energy range

    CERN Document Server

    Paramonov, V

    2013-01-01

    The Disk Loaded Waveguide (DLW) is the mostly used high frequency structure for acceleration of lightweight particles - electrons in the high energy range. In some physical experiments acceleration of more heavy particles - muons to medium energies is required. DLW parameters are considered for particle velocity 0.04 < \\beta < 1 both for the fundamental and the nearest backward spatial harmonics. Physical and technical restrictions for DLW application in the low \\beta range and lower frequency (the L-band range) are analyzed. Basing on particularities of acceleration with Traveling Wave (TW), deep optimization of DLW cells dimensions, the choice of optimal operating phase advance for each DLW section and combination of forward and backward TW modes, it is possible to create simple, cost effective acceleration system for acceleration in the velocity range 0.2 < \\beta < 1 intermediate particles, in some parameters overcoming accelerating system with RF cavities in Standing Wave (SW) mode. Design cri...

  16. Linear Free Energy Correlations for Fission Product Release from the Fukushima-Daiichi Nuclear Accident

    Energy Technology Data Exchange (ETDEWEB)

    Abrecht, David G.; Schwantes, Jon M.

    2015-03-03

    This paper extends the preliminary linear free energy correlations for radionuclide release performed by Schwantes, et al., following the Fukushima-Daiichi Nuclear Power Plant accident. Through evaluations of the molar fractionations of radionuclides deposited in the soil relative to modeled radionuclide inventories, we confirm the source of the radionuclides to be from active reactors rather than the spent fuel pool. Linear correlations of the form ln χ = -α (ΔGrxn°(TC))/(RTC)+β were obtained between the deposited concentration and the reduction potential of the fission product oxide species using multiple reduction schemes to calculate ΔG°rxn(TC). These models allowed an estimate of the upper bound for the reactor temperatures of TC between 2130 K and 2220 K, providing insight into the limiting factors to vaporization and release of fission products during the reactor accident. Estimates of the release of medium-lived fission products 90Sr, 121mSn, 147Pm, 144Ce, 152Eu, 154Eu, 155Eu, 151Sm through atmospheric venting and releases during the first month following the accident were performed, and indicate large quantities of 90Sr and radioactive lanthanides were likely to remain in the damaged reactor cores.

  17. Linear free energy correlations for fission product release from the Fukushima-Daiichi nuclear accident.

    Science.gov (United States)

    Abrecht, David G; Schwantes, Jon M

    2015-03-03

    This paper extends the preliminary linear free energy correlations for radionuclide release performed by Schwantes et al., following the Fukushima-Daiichi Nuclear Power Plant accident. Through evaluations of the molar fractionations of radionuclides deposited in the soil relative to modeled radionuclide inventories, we confirm the initial source of the radionuclides to the environment to be from active reactors rather than the spent fuel pool. Linear correlations of the form In χ = −α ((ΔGrxn°(TC))/(RTC)) + β were obtained between the deposited concentrations, and the reduction potentials of the fission product oxide species using multiple reduction schemes to calculate ΔG°rxn (TC). These models allowed an estimate of the upper bound for the reactor temperatures of TC between 2015 and 2060 K, providing insight into the limiting factors to vaporization and release of fission products during the reactor accident. Estimates of the release of medium-lived fission products 90Sr, 121mSn, 147Pm, 144Ce, 152Eu, 154Eu, 155Eu, and 151Sm through atmospheric venting during the first month following the accident were obtained, indicating that large quantities of 90Sr and radioactive lanthanides were likely to remain in the damaged reactor cores.

  18. Understanding Low Energy Gamma Emission from Fission and Capture with DANCE

    Science.gov (United States)

    Wilburn, Grey; Couture, Aaron; Mosby, Shea

    2012-10-01

    Los Alamos National Laboratory's Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 barium fluoride (BaF2) detectors in a 4π array used to study cross-section measurements from neutron capture reactions. Further, recent studies have taken advantage of DANCE to study the gamma emission from fission, which is not well characterized. Neutron capture is studied because of its relevance to nuclear astrophysics (almost all elements heavier than iron are formed via neutron capture) and nuclear energy, where neutron capture is a poison in the reactor. Gamma ray cascades following neutron capture and fission include photons with energies between 100 keV and 10 MeV. DANCE uses a ^6LiH sphere to attenuate scattered neutrons, the primary background in DANCE. Unfortunately, it also attenuates low energy gamma rays. In order to quantify this effect and validate simulations, direct measurements of low energy gammas were made with a high purity germanium (HPGe) crystal. HPGe's allow for high resolution measurements of low energy gamma rays that are not possible using the BaF2 crystals. The results and their agreement with simulations will be discussed.

  19. Role of near threshold resonances in intermediate energy nuclear physics

    Indian Academy of Sciences (India)

    B K Jain; N J Upadhyay

    2014-11-01

    The presence of a resonance close to the threshold strongly effects the dynamics of the interacting particles at low energies. Production of 12C, the element for life, in 4He burning in Sun is a classic example of such a situation. In intermediate energy nuclear physics, this situation arises in the interactions of an -meson with a nucleon and that of a −-meson with a proton at low energies, where both these systems have a resonance or a bound state near their thresholds, resulting in a strong attractive interaction. If putting these mesons in nuclear environment produces a strong attraction, it is possible that, in nature there may exist - and −-nuclear bound states. Such a tantalizing possibility has led to experimental and theoretical programmes to search for them. These efforts have produced positive results. This paper gives a brief critical overview of these studies, emphasizing especially the efforts led by Bhabha Atomic Research Centre (BARC).

  20. Fission of 255,256Es, 255-257Fm, and 258Md at moderate excitation energies

    NARCIS (Netherlands)

    Britt, H.C.; Hoffman, D.C.; Plicht, J. van der; Wilhelmy, J.; Cheifetz, E.; Dupzyk, R.J.; Lougheed, R.W.

    1984-01-01

    The fission of 255,256Es, 255-257Fm, and 258Md has been studied in the excitation energy range from threshold to 25 MeV. A target of 254Es was used in the direct reaction studies; (d,pf), (t,pf), (3He,df), (3He,pf), and in the compound induced fission reactions formed with p, d, t, and α particle pr

  1. Fission of 255,256Es, 255-257Fm, and 258Md at moderate excitation energies

    NARCIS (Netherlands)

    Britt, H.C.; Hoffman, D.C.; Plicht, J. van der; Wilhelmy, J.; Cheifetz, E.; Dupzyk, R.J.; Lougheed, R.W.

    1984-01-01

    The fission of 255,256Es, 255-257Fm, and 258Md has been studied in the excitation energy range from threshold to 25 MeV. A target of 254Es was used in the direct reaction studies; (d,pf), (t,pf), (3He,df), (3He,pf), and in the compound induced fission reactions formed with p, d, t, and α particle

  2. On the Analysis of Intermediate-Energy Coulomb Excitation Experiments

    CERN Document Server

    Scheit, Heiko; Glasmacher, Thomas; Motobayashi, Tohru

    2008-01-01

    In a recent publication (Bertulani et al., PLB 650 (2007) 233 and arXiv:0704.0060v2) the validity of analysis methods used for intermediate-energy Coulomb excitation experiments was called into question. Applying a refined theory large corrections of results in the literature seemed needed. We show that this is not the case and that the large deviations observed are due to the use of the wrong experimental parameters. We furthermore show that an approximate expression derived by Bertulani et al. is in fact equivalent to the theory of Winther and Alder (NPA 319 (1979) 518), an analysis method often used in the literature.

  3. Intermediate energy semileptonic probes of the hadronic neutral current

    Energy Technology Data Exchange (ETDEWEB)

    Musolf, M.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States)]|[Old Dominion Univ., Norfolk, VA (United States). Dept. of Physics]|[CEBAF Theory Group, Newport News, VA (United States); Donnelly, T.W. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Dubach, J. [Massachusetts Univ., Amherst, MA (United States). Dept. of Physics and Astronomy; Pollock, S.J. [Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory]|[Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands). Sectie K; Kowalski, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Beise, E.J. [California Inst. of Tech., Pasadena, CA (United States). W.K. Kellogg Radiation Lab.]|[Maryland Univ., College Park, MD (United States). Dept. of Physics

    1993-06-01

    The present status and future prospects of intermediate-energy semileptonic neutral current studies are reviewed. Possibilities for using parity-violating electron scattering from nucleons and nuclei to study hadron structure and nuclear dynamics are emphasized, with particular attention paid to probes of strangeness content in the nucleon. Connections are drawn between such studies and tests of the electroweak gauge theory using electron or neutrino scattering. Outstanding theoretical issues in the interpretation of semileptonic neutral current measurements are highlighted and the prospects for undertaking parity-violating electron or neutrino scattering experiments in the near future are surveyed.

  4. Intermediate-energy Coulomb excitation of Na30

    Science.gov (United States)

    Ettenauer, S.; Zwahlen, H.; Adrich, P.; Bazin, D.; Campbell, C. M.; Cook, J. M.; Davies, A. D.; Dinca, D.-C.; Gade, A.; Glasmacher, T.; Lecouey, J.-L.; Mueller, W. F.; Otsuka, T.; Reynolds, R. R.; Riley, L. A.; Terry, J. R.; Utsuno, Y.; Yoneda, K.

    2008-07-01

    The neutron-rich nucleus Na30 in the vicinity of the “Island of Inversion” was investigated using intermediate-energy Coulomb excitation. A single γ-ray transition was observed and attributed to the 31+→2gs+ decay. A transition probability of B(E2;2gs+→31+)=147(21)e2fm4 was determined and found in agreement with a previous experiment and with large-scale shell-model calculations. Evidence for the strong excitation of the 41+ state predicted by the shell-model calculations was not observed.

  5. Spontaneous Fission and alpha -Decay Half-Lives of Superheavy Nuclei in Different Macroscopic Energy Models

    CERN Document Server

    Lojewski, Z; Pomorski, K

    2003-01-01

    Spontaneous fission half-lives (T sub s sub f) of the heaviest nuclei are calculated in the macroscopic-microscopic approach based on the deformed Woods-Saxon potential. Four different models of the macroscopic energy are examined and their influence on the results is discussed. The calculations of (T sub s sub f) are performed within WKB approximation. Multi-dimensional dynamical-programming method (MDP) is applied to minimize the action integral in a 3-dimensional space of deformation parameters describing the nuclear shape (beta sub 2 ,beta sub 4 ,beta sub 6).

  6. Elastic proton-deuteron scattering at intermediate energies

    CERN Document Server

    Ramazani-Moghaddam-Arani, A; Bacher, A D; Bailey, C D; Biegun, A; Eslami-Kalantari, M; Gašparić, I; Joulaeizadeh, L; Kalantar-Nayestanaki, N; Kistryn, St; Kozela, A; Mardanpour, H; Messchendorp, J G; Micherdzinska, A M; Moeini, H; Shende, S V; Stephan, E; Stephenson, E J; Sworst, R

    2008-01-01

    Observables in elastic proton-deuteron scattering are sensitive probes of the nucleon-nucleon interaction and three-nucleon force effects. The present experimental data base for this reaction is large, but contains a large discrepancy between data sets for the differential cross section taken at 135 MeV/nucleon by two experimental research groups. This paper reviews the background of this problem and presents new data taken at KVI. Differential cross sections and analyzing powers for the $^{2}{\\rm H}(\\vec p,d){p}$ and ${\\rm H}(\\vec d,d){p}$ reactions at 135 MeV/nucleon and 65 MeV/nucleon, respectively, have been measured. The data differ significantly from previous measurements and consistently follow the energy dependence as expected from an interpolation of published data taken over a large range at intermediate energies.

  7. Elastic proton-deuteron scattering at intermediate energies

    Science.gov (United States)

    Ramazani-Moghaddam-Arani, A.; Amir-Ahmadi, H. R.; Bacher, A. D.; Bailey, C. D.; Biegun, A.; Eslami-Kalantari, M.; Gašparić, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Micherdzinska, A. M.; Moeini, H.; Shende, S. V.; Stephan, E.; Stephenson, E. J.; Sworst, R.

    2008-07-01

    Observables in elastic proton-deuteron scattering are sensitive probes of the nucleon-nucleon interaction and three-nucleon force effects. The present experimental database for this reaction is large, but contains a large discrepancy between data sets for the differential cross section taken at 135 MeV/nucleon by two experimental research groups. This article reviews the background of this problem and presents new data taken at Kernfysisch Versneller Instituute (KVI). Differential cross sections and analyzing powers for the 2H(p→,d)p and 1H(d→,d)p reactions at 135 MeV/nucleon and 65 MeV/nucleon, respectively, have been measured. The differential cross-section data differ significantly from previous measurements and consistently follow the energy dependence as expected from an interpolation of published data taken over a large range at intermediate energies.

  8. Intermediate evaluation of USAID/Cairo energy policy planning project

    Energy Technology Data Exchange (ETDEWEB)

    Wilbanks, T.J.; Wright, S.B. (Oak Ridge National Lab., TN (United States)); Barron, W.F. (Hong Kong Univ. (Hong Kong)); Kamel, A.M. (Ain Shams Univ., Cairo (Egypt)); Santiago, H.T. (USDOE, Washington, DC (United States))

    1992-01-01

    Three years ago, a team from the Oak Ridge National Laboratory and the Oak Ridge Associated Universities, supplemented by an expert from the US Department of Energy and a senior Egyptian energy professional, carried out what was termed an intermediate evaluation'' of a major energy policy project in Egypt. Supported by USAID/Cairo, the project had concentrated on developing and strengthening an Organization for Energy Planning (OEP) within the Government of India, and it was actually scheduled to end less than a year after this evaluation. The evaluation was submitted to USAID/Cairo and circulated elsewhere in the US Agency for International Development and the Government of Egypt as an internal report. Over the next several years, the USAID energy planning project ended and the functions performed by OEP were merged with planning capabilities in the electric power sector. Now that the major issues addressed by the evaluation report have been resolved, we are making it available to a broader audience as a contribution to the general literature on development project evaluation and institution-building.

  9. Intermediate evaluation of USAID/Cairo energy policy planning project

    Energy Technology Data Exchange (ETDEWEB)

    Wilbanks, T.J.; Wright, S.B. [Oak Ridge National Lab., TN (United States); Barron, W.F. [Hong Kong Univ. (Hong Kong); Kamel, A.M. [Ain Shams Univ., Cairo (Egypt); Santiago, H.T. [USDOE, Washington, DC (United States)

    1992-09-01

    Three years ago, a team from the Oak Ridge National Laboratory and the Oak Ridge Associated Universities, supplemented by an expert from the US Department of Energy and a senior Egyptian energy professional, carried out what was termed an ``intermediate evaluation`` of a major energy policy project in Egypt. Supported by USAID/Cairo, the project had concentrated on developing and strengthening an Organization for Energy Planning (OEP) within the Government of India, and it was actually scheduled to end less than a year after this evaluation. The evaluation was submitted to USAID/Cairo and circulated elsewhere in the US Agency for International Development and the Government of Egypt as an internal report. Over the next several years, the USAID energy planning project ended and the functions performed by OEP were merged with planning capabilities in the electric power sector. Now that the major issues addressed by the evaluation report have been resolved, we are making it available to a broader audience as a contribution to the general literature on development project evaluation and institution-building.

  10. Microscopic description of fission in nobelium isotopes with the Gogny-D1M energy density functional

    CERN Document Server

    Rodriguez-Guzman, R

    2016-01-01

    Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in the isotopes $^{250-260}$No. The even-even isotopes have been considered within the standard Hartree-Fock-Bogoliobov (HFB) framework while for the odd-mass ones the Equal Filling Approximation (HFB-EFA) has been employed. Ground state quantum numbers and deformations, pairing energies, one-neutron separation energies, inner and outer barrier heights as well as fission isomer excitation energies are given. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the systematic of the spontaneous fission half-lives t$_\\mathrm{SF}$ both for even-even and odd-mass nuclei. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation, it is shown that both the specialization energy and the pairing quenching effects, taken into account within the self-consistent HF...

  11. Microscopic description of fission in nobelium isotopes with the Gogny-D1M energy density functional

    Science.gov (United States)

    Rodríguez-Guzmán, R.; Robledo, L. M.

    2016-11-01

    Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in the isotopes 250-260No . The even-even isotopes have been considered within the standard Hartree-Fock-Bogoliobov (HFB) framework while for the odd-mass ones the Equal Filling Approximation (HFB-EFA) has been employed. Ground state quantum numbers and deformations, pairing energies, one-neutron separation energies, inner and outer barrier heights as well as fission isomer excitation energies are given. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the systematic of the spontaneous fission half-lives t_SF both for even-even and odd-mass nuclei. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation, it is shown that both the specialization energy and the pairing quenching effects, taken into account within the self-consistent HFB-EFA blocking procedure, lead to larger t_SF values in odd-mass nuclei as compared with their even-even neighbors. Alpha decay lifetimes have also been computed using a parametrization of the Viola-Seaborg formula. The high quality of the Gogny-D1M functional regarding nuclear masses leads to a very good reproduction of Q_{α} values and consequently of lifetimes.

  12. $\\gamma$-ray energy spectra and multiplicities from the neutron-induced fission of $^{235}$U using STEFF

    CERN Multimedia

    An experiment is proposed to use the STEFF spectrometer at n_TOF to study fragment $\\gamma$-correlations following the neutron-induced fission of $^{235}$U. The STEFF array of 12 NaI detectors will allow measurements of the single $\\gamma$-energy, the $\\gamma$ multiplicity, and the summed $\\gamma$energy distributions as a function of the mass and charge split, and deduced excitation energy in the fission event. These data will be used to study the origin of fission-fragment angular momenta, examining angular distribution eects as a function of incident neutron energy. The principal application of this work is in meeting the NEA high-priority request for improved $\\gamma$ray data from $^{235}$U(n; F). To improve the detection rate and expand the range of detection angles, STEFF will be modied to include two new ssion-fragment detectors each at 45 to the beam direction.

  13. Laser inertial fusion-based energy: Neutronic design aspects of a hybrid fusion-fission nuclear energy system

    Science.gov (United States)

    Kramer, Kevin James

    This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 mum of tungsten to mitigate x-ray damage. The first wall is cooled by Li17Pb83 eutectic, chosen for its neutron multiplication and good heat transfer properties. The Li17Pb 83 flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li17Pb83, separated from the Li17Pb83 by a solid ODS wall. This main system coolant is the molten salt flibe (2LiF-BeF2), chosen for beneficial neutronics and heat transfer properties. The use of flibe enables both fusion fuel production (tritium) and neutron moderation and multiplication for the fission blanket. A Be pebble (1 cm diameter) multiplier layer surrounds the coolant injection plenum and the coolant flows radially through perforated walls across the bed. Outside the Be layer, a fission fuel layer comprised of depleted uranium contained in Tristructural-isotropic (TRISO) fuel particles having a packing fraction of 20% in 2 cm diameter fuel pebbles. The fission blanket is cooled by

  14. Complex fission phenomena

    CERN Document Server

    Poenaru, D N; Greiner, W

    2005-01-01

    Complex fission phenomena can be studied in a unified way. Very general reflection asymmetrical equilibrium (saddle-point) nuclear shapes, may be obtained by solving an integro-differential equation without being necessary to specify a certain parametrization. The mass asymmetry in cold fission phenomena can be explained as the result of adding a phenomenological shell correction to the liquid drop model deformation energy. Applications to binary, ternary, and quaternary fission are outlined. Predictions of two alpha accompanied fission are experimentally confirmed.

  15. Comparative evaluation of solar, fission, fusion, and fossil energy resources, part 3

    Science.gov (United States)

    Clement, J. D.; Reupke, W. A.

    1974-01-01

    The role of nuclear fission reactors in becoming an important power source in the world is discussed. The supply of fissile nuclear fuel will be severely depleted by the year 2000. With breeder reactors the world supply of uranium could last thousands of years. However, breeder reactors have problems of a large radioactive inventory and an accident potential which could present an unacceptable hazard. Although breeder reactors afford a possible solution to the energy shortage, their ultimate role will depend on demonstrated safety and acceptable risks and environmental effects. Fusion power would also be a long range, essentially permanent, solution to the world's energy problem. Fusion appears to compare favorably with breeders in safety and environmental effects. Research comparing a controlled fusion reactor with the breeder reactor in solving our long range energy needs is discussed.

  16. Statistical and dynamical aspects of intermediate energy nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ghetti, R.

    1997-01-01

    Studies of intermediate energy heavy ion reactions have revealed that the probability of emitting n-fragments is reducible to the probability of emitting a single fragment through the binomial distribution. The resulting one-fragment probability shows a dependence on the thermal energy that is characteristic of statistical decay. Similarly, the charge distributions associated with n-fragment emission are reducible to the one-fragment charge distribution, and thermal scaling is observed. The reducibility equation for the n-fragment charge distribution contains a quantity with a value that starts from zero, at low transverse energies, and saturates at high transverse energies. This evolution may signal a transition from a coexistence phase to a vapour phase. In the search for a signal of liquid-gas phase transition, the appearance of intermittency is reconsidered. Percolation calculations, as well as data analysis, indicate that an intermittent-like signal appears from classes of events that do not coincide with the critical one. 232 refs.

  17. Systematics of photopion reaction yields at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Hiroshi [Kanazawa Univ. (Japan). Faculty of Science

    1996-03-01

    Our development in radiochemical measurements of photopion yields from complex nuclei ranging from {sup 7}Li to {sup 209}Bi at intermediate energies is reviewed. It has been found from systematized yields with respect to photon-energies, types of photopion reaction and target masses that (1) photons responsible for the ({gamma}, {pi}{sup +}), ({gamma}, {pi}{sup -}) and ({gamma}, {pi}{sup -}xn) reactions upto x=9 are mostly of energies lower than 400 MeV but higher than 140 MeV (pion rest mass), (2) ({gamma}, {pi}{sup +}) and ({gamma}, {pi}{sup -}) yields are independent of target mass (A{sub t}) heavier than A{sub t}{approx}30, and the yield ratio of Y({gamma}, {pi}{sup -})/Y({gamma}, {pi}{sup +}) is 5-6 irrespective of photon energies concerned, and (3) the yield variations of ({gamma}, {pi}{sup -}xn) reactions are well expressed as functions of (N/Z) of targets and neutron multiplicity. These findings appear to imply requirements of new concepts on neutron density distributions and photonuclear processes in complex nuclei. (author)

  18. Modelling interaction cross sections for intermediate and low energy ions

    Energy Technology Data Exchange (ETDEWEB)

    Toburen, L.H.; Shinpaugh, J.L.; Justiniano, E.L.B

    2002-07-01

    When charged particles slow in tissue they undergo electron capture and loss processes than can have profound effects on subsequent interaction cross sections. Although a large amount of data exists for the interaction of bare charged particles with atoms and molecules, few experiments have been reported for these 'dressed' particles. Projectile electrons contribute to an impact-parameter-dependent screening of the projectile charge that precludes straightforward scaling of energy loss cross sections from those of bare charged particles. The objective of this work is to develop an analytical model for the energy-loss-dependent effects of screening on differential ionisation cross sections that can be used in track structure calculations for high LET ions. As a first step a model of differential ionisation cross sections for bare ions has been combined with a simple screening model to explore cross sections for intermediate and low energy dressed ions in collisions with atomic and molecular gas targets. The model is described briefly and preliminary results compared to measured electron energy spectra. (author)

  19. Modelling interaction cross sections for intermediate and low energy ions.

    Science.gov (United States)

    Toburen, L H; Shinpaugh, J L; Justiniano, E L B

    2002-01-01

    When charged particles slow in tissue they undergo electron capture and loss processes that can have profound effects on subsequent interaction cross sections. Although a large amount of data exists for the interaction of bare charged particles with atoms and molecules, few experiments have been reported for these 'dressed' particles. Projectile electrons contribute to an impact-parameter-dependent screening of the projectile charge that precludes straightforward scaling of energy loss cross sections from those of bare charged particles. The objective of this work is to develop an analytical model for the energy-loss-dependent effects of screening on differential ionisation cross sections that can be used in track structure calculations for high LET ions. As a first step a model of differential ionisation cross sections for bare ions has been combined with a simple screening model to explore cross sections for intermediate and low energy dressed ions in collisions with atomic and molecular gas targets. The model is described briefly and preliminary results compared to measured ejected electron energy spectra.

  20. New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products.

    Science.gov (United States)

    Fallot, M; Cormon, S; Estienne, M; Algora, A; Bui, V M; Cucoanes, A; Elnimr, M; Giot, L; Jordan, D; Martino, J; Onillon, A; Porta, A; Pronost, G; Remoto, A; Taín, J L; Yermia, F; Zakari-Issoufou, A-A

    2012-11-16

    In this Letter, we study the impact of the inclusion of the recently measured beta decay properties of the (102;104;105;106;107)Tc, (105)Mo, and (101)Nb nuclei in an updated calculation of the antineutrino energy spectra of the four fissible isotopes (235,238)U and (239,241)Pu. These actinides are the main contributors to the fission processes in pressurized water reactors. The beta feeding probabilities of the above-mentioned Tc, Mo, and Nb isotopes have been found to play a major role in the γ component of the decay heat of (239)Pu, solving a large part of the γ discrepancy in the 4-3000 s range. They have been measured by using the total absorption technique, insensitive to the pandemonium effect. The calculations are performed by using the information available nowadays in the nuclear databases, summing all the contributions of the beta decay branches of the fission products. Our results provide a new prediction of the antineutrino energy spectra of (235)U, (239,241)Pu, and, in particular, (238)U for which no measurement has been published yet. We conclude that new total absorption technique measurements are mandatory to improve the reliability of the predicted spectra.

  1. New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products

    CERN Document Server

    Fallot, M; Estienne, M; Algora, A; Bui, V M; Cucoanes, A; Elnimr, M; Giot, L; Jordan, D; Martino, J; Onillon, A; Porta, A; Pronost, G; Taín, J L; Yermia, F; Zakari-Issoufou, A -A

    2012-01-01

    In this paper, we study the impact of the inclusion of the recently measured beta decay properties of the $^{102;104;105;106;107}$Tc, $^{105}$Mo, and $^{101}$Nb nuclei in an updated calculation of the antineutrino energy spectra of the four fissible isotopes $^{235, 238}$U, and $^{239,241}$Pu. These actinides are the main contributors to the fission processes in Pressurized Water Reactors. The beta feeding probabilities of the above-mentioned Tc, Mo and Nb isotopes have been found to play a major role in the $\\gamma$ component of the decay heat of $^{239}$Pu, solving a large part of the $\\gamma$ discrepancy in the 4 to 3000\\,s range. They have been measured using the Total Absorption Technique (TAS), avoiding the Pandemonium effect. The calculations are performed using the information available nowadays in the nuclear databases, summing all the contributions of the beta decay branches of the fission products. Our results provide a new prediction of the antineutrino energy spectra of $^{235}$U, $^{239,241}$Pu ...

  2. Determination of the Spectral Index in the Fission Spectrum Energy Regime

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Amy Sarah [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-16

    Neutron reaction cross sections play a vital role in tracking the production and destruction of isotopes exposed to neutron fluence. They are central to the process of reconciling the initial and final atom inventories. Measurements of irradiated samples by radiochemical methods in tangent with an algorithm are used to evaluate the fluence a sample is exposed to over the course of the irradiation. This algorithm is the Isotope Production Code (IPC) created and used by the radiochemistry data assessment team at Los Alamos National Laboratory (LANL). An integral result is calculated by varying the total neutron fluence seen by a sample. A sample, irradiated in a critical assembly, will be exposed to a unique neutron flux defined by the neutron source and distance of the sample from the source. Neutron cross sections utilized are a function of the hardness of the neutron spectrum at the location of irradiation. A spectral index is used an indicator of the hardness of the neutron spectrum. Cross sections fit forms applied in IPC are collapsed from a LANL 30-group energy structure. Several decades of research and development have been performed to formalize the current IPC cross section library. Basis of the current fission spectrum neutron reaction cross section library is rooted in critical assembly experiments performed from the 1950’s through the early 1970’s at LANL. The focus of this report is development of the spectral index used an indicator of the hardness of the neutron spectrum in the fission spectrum energy regime.

  3. Hipse: an event generator for nuclear collisions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Lacroix, D.; Van Lauwe, A.; Durand, D

    2003-11-01

    An event generator, HIPSE (Heavy-Ion Phase-Space Exploration), dedicated to the description of nuclear collisions in the intermediate energy range is presented. Based on the sudden approximation and on geometrical hypothesis, it can conveniently simulate heavy-ion interactions at all impact parameters and thus can constitute a valuable tool for the understanding of processes such as neck emission or multifragmentation in peripheral or/and central collisions. After a detailed description of the ingredients of the model, first comparisons with experimental data collected by the INDRA collaboration are shown. Special emphasis is put on the kinematical characteristics of fragments and light particles observed at all impact parameters for Xe+Sn reactions at 25 and 50 MeV/u and Ni + Ni at 82 MeV/u. (authors)

  4. Electron scattering by O2 at intermediate and high energies

    Institute of Scientific and Technical Information of China (English)

    Deheng Shi; Jinfeng Sun; Xiangdong Yang; Zunlue Zhu; Yufang Liu

    2005-01-01

    @@ A complex optical model potential correlated by the concept of bonded atoms, which considers the overlapping effect of electron clouds between two atoms in a molecule, is firstly employed to calculate the absolute differential cross sections, the integrated and momentum transfer cross sections for electrons scattered by O2 at intermediate and high energies by using additivity rule model at Hartree-Fock level. In the study,the complex optical model potential is composed of static, exchange, correlation polarization plus absorption contributions. The quantitative absolute differential cross sections, the integrated and momentum transfer cross sections are obtained. Compared with available experimental data, this approach presents good results. It is shown that the additivity rule model together with the complex optical model potential correlated by the concept of bonded atoms is completely suitable for the calculations of the absolute differential cross sections, the integrated and momentum transfer cross sections.

  5. Validation of Geant4 hadronic physics models at intermediate energies

    Science.gov (United States)

    Banerjee, Sunanda; Geant4 Hadronic Group

    2010-04-01

    GEANT4 provides a number of physics models at intermediate energies (corresponding to incident momenta in the range 1-20 GeV/c). Recently, these models have been validated with existing data from a number of experiments: (a) inclusive proton and neutron production with a variety of beams (π-, π+, p) at different energies between 1 and 9 GeV/c on a number of nuclear targets (from beryllium to uranium); (2) inclusive pion/kaon/proton production from 14.6 GeV/c proton beams on nuclear targets (from beryllium to gold); (3) inclusive pion production from pion beams between 3-13 GeV/c on a number of nuclear targets (from beryllium to lead). The results of simulation/data comparison for different GEANT4 models are discussed in the context of validating the models and determining their usage in physics lists for high energy application. Due to the increasing number of validations becoming available, and the requirement that they be done at regular intervals corresponding to the GEANT4 release schedule, automated methods of validation are being developed.

  6. Fission fragment charge and mass distributions in 239Pu(n ,f ) in the adiabatic nuclear energy density functional theory

    Science.gov (United States)

    Regnier, D.; Dubray, N.; Schunck, N.; Verrière, M.

    2016-05-01

    Background: Accurate knowledge of fission fragment yields is an essential ingredient of numerous applications ranging from the formation of elements in the r process to fuel cycle optimization for nuclear energy. The need for a predictive theory applicable where no data are available, together with the variety of potential applications, is an incentive to develop a fully microscopic approach to fission dynamics. Purpose: In this work, we calculate the pre-neutron emission charge and mass distributions of the fission fragments formed in the neutron-induced fission of 239Pu using a microscopic method based on nuclear density functional theory (DFT). Methods: Our theoretical framework is the nuclear energy density functional (EDF) method, where large-amplitude collective motion is treated adiabatically by using the time-dependent generator coordinate method (TDGCM) under the Gaussian overlap approximation (GOA). In practice, the TDGCM is implemented in two steps. First, a series of constrained EDF calculations map the configuration and potential-energy landscape of the fissioning system for a small set of collective variables (in this work, the axial quadrupole and octupole moments of the nucleus). Then, nuclear dynamics is modeled by propagating a collective wave packet on the potential-energy surface. Fission fragment distributions are extracted from the flux of the collective wave packet through the scission line. Results: We find that the main characteristics of the fission charge and mass distributions can be well reproduced by existing energy functionals even in two-dimensional collective spaces. Theory and experiment agree typically within two mass units for the position of the asymmetric peak. As expected, calculations are sensitive to the structure of the initial state and the prescription for the collective inertia. We emphasize that results are also sensitive to the continuity of the collective landscape near scission. Conclusions: Our analysis confirms

  7. Ternary fission

    Indian Academy of Sciences (India)

    M Balasubramaniam; K R Vijayaraghavan; C Karthikraj

    2015-09-01

    We present the ternary fission of 252Cf and 236U within a three-cluster model as well as in a level density approach. The competition between collinear and equatorial geometry is studied by calculating the ternary fragmentation potential as a function of the angle between the lines joining the stationary middle fragment and the two end fragments. The obtained results for the 16O accompanying ternary fission indicate that collinear configuration is preferred to equatorial configuration. Further, for all the possible third fragments, the potential energy surface (PES) is calculated corresponding to an arrangement in which the heaviest and the lightest fragments are considered at the end in a collinear configuration. The PES reveals several possible ternary modes including true ternary modes where the three fragments are of similar size. The complete mass distributions of Si and Ca which accompanied ternary fission of 236U is studied within a level density picture. The obtained results favour several possible ternary combinations.

  8. Thermal fission rates with temperature dependent fission barriers

    CERN Document Server

    Zhu, Yi

    2016-01-01

    \\item[Background] The fission processes of thermal excited nuclei are conventionally studied by statistical models which rely on inputs of phenomenological level densities and potential barriers. Therefore the microscopic descriptions of spontaneous fission and induced fission are very desirable for a unified understanding of various fission processes. \\item[Purpose] We propose to study the fission rates, at both low and high temperatures, with microscopically calculated temperature-dependent fission barriers and mass parameters. \\item[Methods] The fission barriers are calculated by the finite-temperature Skyrme-Hartree-Fock+BCS method. The mass parameters are calculated by the temperature-dependent cranking approximation. The thermal fission rates can be obtained by the imaginary free energy approach at all temperatures, in which fission barriers are naturally temperature dependent. The fission at low temperatures can be described mainly as a barrier-tunneling process. While the fission at high temperatures ...

  9. Photon emission in neutral current interactions at intermediate energies

    CERN Document Server

    Wang, E; Nieves, J

    2014-01-01

    Neutral current photon emission reactions with nucleons and nuclei are studied. These processes are important backgrounds for nu_mu to nu_e (bar(nu)_mu to bar(nu)_e) appearance oscillation experiments where electromagnetic showers instigated by electrons (positrons) and photons are not distinguishable. At intermediate energies, these reactions are dominated by the weak excitation of the Delta(1232) resonance and its subsequent decay into Ngamma There are also non-resonant contributions that, close to threshold, are fully determined by the effective chiral Lagrangian of strong interactions. In addition, we have also included mechanisms mediated by nucleon excitations (N*) from the second resonance region above the Delta(1232). From these states, the contribution of the D13 N*(1520) turns out to be sizable for (anti)neutrino energies above 1.5 GeV. We have extended the model to nuclear targets taking, into account Pauli blocking, Fermi motion and the in-medium Delta resonance broadening. We present our predicti...

  10. MCNP6 fragmentation of light nuclei at intermediate energies

    CERN Document Server

    Mashnik, Stepan G

    2014-01-01

    Fragmentation reactions induced on light target nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the latest Los Alamos Monte Carlo transport code MCNP6 and with its cascade-exciton model (CEM) and Los Alamos version of the quark-gluon string model (LAQGSM) event generators, version 03.03, used as stand-alone codes. Such reactions are involved in different applications, like cosmic-ray-induced single event upsets (SEU's), radiation protection, and cancer therapy with proton and ion beams, among others; therefore, it is important that MCNP6 simulates them as well as possible. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after INC. Both CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to He4 from energetic nucleons ...

  11. Signatures of special nuclear material: High-energy gamma rays following fission

    Energy Technology Data Exchange (ETDEWEB)

    Norman, Eric B.; Prussin, Stanley G.; Larimer, Ruth-Mary; Shugart, Howard; Browne, Edgardo; Smith, Alan R.; McDonald, Rchard J.; Nitsche, Heino; Gupta, Puja; Frank, Michael I.; Gosnell, Thomas B.

    2003-05-29

    Since September 11, 2001, much effort has been devoted to the development of new and improved means for the detection and prevention of the clandestine transport of special nuclear material (SNM, i.e. {sup 235}U or {sup 239}Pu) and other materials for producing weapons of mass destruction. In a recent Brief Communication, Borozdin et al. showed that cosmic-ray muons could be used to image dense objects inside containers. Here we describe a method for unequivocally identifying SNM in large seagoing containers. Our method is based on the fact that neutron-induced fission of {sup 235}U or {sup 239}Pu is followed by {beta} decays of short-lived fission fragments during which large numbers of high-energy {gamma} rays (above 3000 keV) are emitted. These {gamma} rays have energies above those of natural {gamma} background, are emitted with significantly greater intensity per fission than {beta}-delayed neutrons, have much higher probabilities of escaping hydrogenous cargo loadings than neutrons, and their energy spectra and time dependencies provide a unique signature of SNM. To demonstrate the main properties of high-energy delayed {gamma} rays, we produced neutrons by bombarding a 1-inch thick water-cooled Be target with 16-MeV deuterons from Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Neutrons were moderated using steel and polyethylene. We employed a pneumatic transfer system to shuttle targets from the irradiation location inside the polyethylene moderator to a remote shielded counting station. We irradiated {sup 235}U (93% isotopic content), {sup 239}Pu (95% isotopic content), wood, polyethylene, aluminum, sandstone, and steel targets for 30 seconds (in a thermal-neutron flux of 1.5 x 10{sup 6}/cm{sup 2}-sec) and acquired 10 sequential {gamma}-ray spectra, each of 3 sec. duration starting 3 sec. after the end of bombardment. We used an 80% relative efficiency coaxial germanium detector and a 30-cm x 30-cm x 10-cm plastic scintillator to detect

  12. Reaction 48Ca+208Pb: the capture-fission cross-sections and the mass-energy distributions of fragments above and deep below the Coulomb barrier

    CERN Document Server

    Prokhorova, E V; Itkis, M G; Kondratev, N A; Kozulin, E M; Krupa, L; Oganessian, Yu T; Pashkevich, V V; Pokrovsky, I V; Rusanov, A Ya; Oganessian, Yu.Ts.

    2003-01-01

    The capture-fission cross-sections in an energy range of 206-242 MeV of 48Ca-projectiles and mass-energy distributions (MEDs) of reaction products in an energy range of 211-242 MeV have been measured in the 48Ca+208Pb reaction using the double-arm time-of-flight spectrometer CORSET. The MEDs of fragments for heated fission were shown to consist of two components. One component, which is due to classical fusion-fission, is associated with the symmetric fission of the 256No compound nucleus. The other component, which appears as ''shoulders'', is associated with the quasi-fission process and can be named ''quasi-fission shoulders''. Those quasi-fission shoulders enclose light fragments whose masses are 60-90 a.m.u. The total kinetic energy (TKE) of the fragments that belong to the shoulders is higher than the value expected for a classical fusion-fission process. We have come to the conclusion that in quasi-fission, spherical shells with Z=28 and N=50 play a great role. It has also been demonstrated that the pr...

  13. Fission Spectrum

    Science.gov (United States)

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  14. Nucleon charge-exchange reactions at intermediate energy

    Energy Technology Data Exchange (ETDEWEB)

    Alford, W.P. [Western Ontario Univ., London, ON (Canada). Dept. of Physics]|[TRIUMF, Vancouver, BC (Canada); Spicer, B.M. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1997-12-31

    An historical review of the development of ideas pertaining to Gamow-Teller giant resonances is given, and a description of the emergence of techniques for the study of charge exchange reactions - particularly the technical advances which yielded the recent volume of new date. The present status of charge exchange reactions is reviewed and assessed. Evidence is presented from the {sup 14}C(p,n) reaction for the dominance of the spin-isospin component of the nucleon-nucleon interaction in intermediate energy reactions. In (p,n) reactions the Gamow-Teller giant resonance dominates the spectra, with higher multipoles contributing. By contrast, in (n,p) reactions in the heavier nuclei, the Gamow-Teller transitions are substantially Pauli-blocked and the spin dipole resonance dominates, with contributions from higher multipoles. Discussions of the multipole decomposition process, used to obtain from the data the contributions of the different multipoles, and the contributions of the multipoles, are given. 226 refs., 19 figs.

  15. Neutron emission effects on final fragments mass and kinetic energy distribution from low energy fission of 34U

    Science.gov (United States)

    Montoya, M.; Rojas, J.; Lobato, I.

    2008-12-01

    The kinetic energy distribution as a function of mass of final fragments (m) from low energy fission of $^{234}U$, measured with the Lohengrin spectrometer by Belhafaf et al. presents a peak around m=108 and another around m = 122. The authors attribute the first peak to the evaporation of a large number of neutrons around the corresponding mass number; and the second peak to the distribution of the primary fragment kinetic energy. Nevertheless, the theoretical calculations related to primary distribution made by Faust et al. do not result in a peak around m = 122. In order to clarify this apparent controversy, we have made a numerical experiment in which the masses and the kinetic energy of final fragments are calculated, assuming an initial distribution of the kinetic energy without peaks on the standard deviation as function of fragment mass. As a result we obtain a pronounced peak on the standard deviation of the kinetic energy distribution around m = 109, a depletion from m = 121 to m = 129, and an small peak around m = 122, which is not as big as the measured by Belhafaf et al. Our simulation also reproduces the experimental results on the yield of the final mass, the average number of emitted neutrons as a function of the provisional mass (calculated from the values of the final kinetic energy of the complementary fragments) and the average value of fragment kinetic energy as a function of the final mass.

  16. Brownian shape motion on five-dimensional potential-energy surfaces:nuclear fission-fragment mass distributions.

    Science.gov (United States)

    Randrup, Jørgen; Möller, Peter

    2011-04-01

    Although nuclear fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the fission-fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.

  17. Brownian shape motion on five-dimensional potential-energy surfaces: Nuclear fission-fragment mass distributions

    CERN Document Server

    Randrup, Jorgen

    2011-01-01

    Although nuclear fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there exists no model with demonstrated predictive power for the fission fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.

  18. Pion- and proton-nucleus interactions at intermediate energy

    Energy Technology Data Exchange (ETDEWEB)

    Dehnhard, D.

    1992-12-01

    We report on scattering and reaction experiments on light nuclei using the [pi]-meson and proton beams from the Los Alamos Meson Physics Facility (LAMPF) and the Indiana University Cyclotron Facility (IUCF). Differential cross sections, cross section asymmetries, and angular correlation functions have been measured in order to test models of the reaction mechanism and of nuclear structure. At LAMPF we have measured asymmetries for pion scattering from polarized [sup 13]C which are uniquely sensitive to the isoscalar spin density. In order to determine details of the reaction mechanism, we have obtained approval for a scattering experiment on polarized [sup 3]He for which the nuclear structure is very well known. We have completed data taking for two studies of elastic scattering of [pi][sup +] from [sup 6]Li and [sup l3]C. The detailed differential cross sections from these experiments will be used to constrain theoretical analyses of previous polarization experiments done at the Pierre-Scherrer-Institute (PSI) and at LAMPF. We have analyzed [pi]-triton coincidence events from the [sup 4]He([pi],[pi][prime] t)p reaction and have found evidence for direct triton knockout from [sup 4]He. We have extended these angular correlation measurements to higher energies and to [sup 2]H and [sup 3]He targets. At IUCF we have performed the first [sup 4]He(p,n) experiment at intermediate energies, T[sub p] = 100, 147, and 200 MeV, in a search for previously reported narrow states in [sup 4]Li of widths of [approx] 1 MeV. Within the statistics of the data we have found no evidence for such narrow structures.

  19. Azimuthal Distributions in Intermediate Energy Heavy-Ion Collisions

    Science.gov (United States)

    Wilson, William Kenneth

    The azimuthal distributions of light particles (Z = 1,2) with respect to the entrance channel reaction plane are investigated with a view towards characterizing the modes of collective motion in intermediate energy heavy -ion collisions. A new technique for reaction plane determination from the distribution of light particles produced in a collision is developed and applied to Ar+V data. The data were acquired using the MSU 4pi Array, a new 215 element large solid angle detector system. At a beam energy of 35 MeV/nucleon, light charged particles are found to exhibit an enhanced emission in the reaction plane which increases with the mass of the detected particle. As the beam energy is increased to 100 MeV/nucleon, the anisotropy nearly vanishes, providing clues to the dynamics of these reactions in a transitional energy regime. The observed anisotropy contains signatures of two distinct modes of collective motion: attractive mean field deflection, and rotation of the fused system. A microscopic calculation based on mean-field mediated interactions plus nucleon-nucleon collisions reproduces both forms of collective motion and their associated azimuthal distributions. The calculation also suggests that the anisotropy due to mean -field deflection is established during the initial stages of the collision. The nature of the nuclear mean-field is further explored using data taken by the 4pi Array for peripheral 50 MeV/nucleon C induced reactions on C and Au targets. Although projectile fragments in grazing collisions are positively deflected by the coulomb force, a specific set of protons are found to be simultaneously attractively deflected by the mean-field towards the opposite side of the reaction plane. This direct observation of attractive mean field deflection supports aspects of the interpretation of the Ar+V data. Lastly, the experimental results are summarized and the potential for extracting more information about the dynamics of heavy-ion collisions using

  20. The nature of singlet exciton fission in carotenoid aggregates.

    Science.gov (United States)

    Musser, Andrew J; Maiuri, Margherita; Brida, Daniele; Cerullo, Giulio; Friend, Richard H; Clark, Jenny

    2015-04-22

    Singlet exciton fission allows the fast and efficient generation of two spin triplet states from one photoexcited singlet. It has the potential to improve organic photovoltaics, enabling efficient coupling to the blue to ultraviolet region of the solar spectrum to capture the energy generally lost as waste heat. However, many questions remain about the underlying fission mechanism. The relation between intermolecular geometry and singlet fission rate and yield is poorly understood and remains one of the most significant barriers to the design of new singlet fission sensitizers. Here we explore the structure-property relationship and examine the mechanism of singlet fission in aggregates of astaxanthin, a small polyene. We isolate five distinct supramolecular structures of astaxanthin generated through self-assembly in solution. Each is capable of undergoing intermolecular singlet fission, with rates of triplet generation and annihilation that can be correlated with intermolecular coupling strength. In contrast with the conventional model of singlet fission in linear molecules, we demonstrate that no intermediate states are involved in the triplet formation: instead, singlet fission occurs directly from the initial 1B(u) photoexcited state on ultrafast time scales. This result demands a re-evaluation of current theories of polyene photophysics and highlights the robustness of carotenoid singlet fission.

  1. Multiplicity and energy of neutrons from {sup 233}U(n{sub th},f) fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Katsuhisa; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan)

    1998-03-01

    The correlation between fission fragments and prompt neutrons from the reaction {sup 233}U(n{sub th},f) was measured with improved accuracy. The results determined the neutron multiplicity and emission energy as a function of fragment mass and total kinetic energy. The average energy as a function of fragment mass followed a nearly symmetric distribution centered about the equal mass-split and formed a remarkable contrast with the saw-tooth distribution of the average neutron multiplicity. The neutron multiplicity from the specified fragment decreases linearly with total kinetic energy, and the slope of multiplicity with kinetic energy had the minimum value at about 130 u. The level density parameter versus mass determined from the neutron data showed a saw-tooth structure with the pronounced minimum at about 128 and generally followed the formula by Gilbert and Cameron, suggesting that the neutron emission process was very much affected by the shell-effect of the fission fragment. (author)

  2. Fission fragment mass distributions via prompt -ray spectroscopy

    Indian Academy of Sciences (India)

    L S Danu; D C Biswas; B K Nayak; R K Choudhury

    2015-09-01

    The distribution of fragment masses formed in nuclear fission is one of the most striking features of the process. Such measurements are very important to understand the shape evolution of the nucleus from ground state to scission through intermediate saddle points. The fission fragment mass distributions, generally obtained via conventional methods (i.e., by measuring the energy and/or the velocity of the correlated fission fragments) are limited to a mass resolution of 4–5 units. On the other hand, by employing the -ray spectroscopy, it is possible to estimate the yield of individual fission fragments. In this work, determination of the fission fragment mass distribution by employing prompt -ray spectroscopy is described along with the recent results on 238U(18O, f) and 238U(32S, f) systems.

  3. Neutron-energy-dependent defect production cross sections for fission and fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Odette, G.R.; Doiron, D.R.

    1976-06-01

    Neutron cross sections for displacements and post-short-term cascade annealing defects are derived from nuclear kinematics calculations of primary atomic recoil energy distributions and the number of secondary defects produced per primary as a function of recoil energy. For the first time, recoil kinematics of charged- and multiple-particle emission reactions are treated rigorously using a compound-nucleus evaporation spectrum nuclear model. Secondary-defect production functions, derived from computer simulation experiments, are taken from the literature. Spectral-averaged defect production cross sections for a fusion reactor first-wall-type environment are on the order of 1.5 to 2.5 times those for a fast fission reactor core-type spectrum. The indicated range of uncertainty is primarily due to secondary-defect production model sensitivity. Nuclear model and data errors are expected to become more significant at high neutron energies, greater than approximately 20 MeV. Fusion reactor environments are found to produce some very energetic recoils and high-energy release events due to charged-particle reactions such as (n,..cap alpha..).

  4. Fission-product yields for thermal-neutron fission of /sup 243/Cm determined from measurements with a high-resolution low-energy germanium gamma-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Merriman, L.D.

    1984-04-01

    Cumulative fission-product yields have been determined for 13 gamma rays emitted during the decay of 12 fission products created by thermal-neutron fission of /sup 243/Cm. A high-resolution low-energy germanium detector was used to measure the pulse-height spectra of gamma rays emitted from a 77-nanogram sample of /sup 243/Cm after the sample had been irradiated by thermal neutrons. Analysis of the data resulted in the identification and matching of gamma-ray energies and half-lives to individual radioisotopes. From these results, 12 cumulative fission product yields were deduced for radionuclides with half-lives between 4.2 min and 84.2 min. 7 references.

  5. Uranium and Plutonium Average Prompt-fission Neutron Energy Spectra (PFNS) from the Analysis of NTS NUEX Data

    Science.gov (United States)

    Lestone, J. P.; Shores, E. F.

    2014-05-01

    In neutron experiments (NUEX) conducted at the Nevada Test Site (NTS) by Los Alamos National Laboratory, the time-of-flight of fission-neutrons emitted from nuclear tests were observed by measuring the current generated by the collection of protons scattered from a thin CH2 foil many meters from the nuclear device into a Faraday cup. The time dependence of the Faraday cup current is a measure of the energy spectrum of the neutrons that leak from the device. With good device models and accurate neutron-transport codes, the leakage spectra can be converted into prompt fast-neutron-induced fission-neutron energy spectra. This has been done for two events containing plutonium, and for an earlier event containing uranium. The prompt-fission neutron spectra have been inferred for 1.5-MeV 239Pu(n,f) and 235U(n,f) reactions for outgoing neutron energies from 1.5 to ∼10.5 MeV, in 1-MeV steps. These spectra are in good agreement with the Los Alamos fission model.

  6. Neutron-induced fission cross sections of 233U and 243Am in the energy range 0.5 Mev En 20 MeV @ n_TOF

    CERN Document Server

    Belloni, F; Milazzo, P M; Calviani, M; Colonna, N; Mastinu, P; Abbondanno, U; Aerts, G; Álvarez, H; Álvarez-Velarde, F; Andriamonje, S; Andrzejewski, J; Assimakopoulos, P; Audouin, L; Badurek, G; Baumann, P; Becvár, F; Berthoumieux, E; Calviño, F; Cano-Ott, D; Capote, R; Carrapiço, C; Cennini, P; Chepel, V; Chiaveri, E; Cortes, G; Couture, A; Cox, J; Dahlfors, M; David, S; Dillmann, I; Domingo-Pardo, C; Dridi, W; Duran, I; Eleftheriadis, C; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Fujii, K; Furman, W; Goncalves, I; González-Romero, E; Gramegna, F; Guerrero, C; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martinez, A; Igashira, M; Jericha, E; Käppeler, F; Kadi, Y; Karadimos, D; Karamanis, D; Kerveno, M; Koehler, P; Kossionides, E; Krticka, M; Lampoudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martínez, T; Massimi, C; Mengoni, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, H; O'Brien, S; Pancin, J; Papachristodoulou, C; Papadopoulos, C; Paradela, C; Patronis, N; Pavlik, A; Pavlopoulos, P; Perrot, L; Pigni, M T; Plag, R; Plompen, A; Plukis, A; Poch, A; Praena, J; Pretel, C; Quesada, J; Rauscher, T; Reifarth, R; Rubbia, C; Rudolf, G; Rullhusen, P; Salgado, J; Santos, C; Sarchiapone, L; Savvidis, I; Stephan, C; Tagliente, G; Tain, J L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vazl, P; Ventura, A; Villamarin, D; Vincente, M C; Vlachoudis, V; Vlastou, R; Voss, F; Walter, S; Wiescher, M; Wisshak, K

    2011-01-01

    Neutron-induced fission cross-sections of actinides have been recently measured at the neutron time of flight facility n_TOF at CERN in the frame of a research project involving isotopes relevant for nuclear astrophysics and nuclear technologies. Fission fragments are detected by a gas counter with good discrimination between nuclear fission products and background events. Neutron-induced fission cross-sections of 233U and 243Am were determined relative to 235U. The present paper reports the results obtained at neutron energies between 0.5 and 20 MeV.

  7. The energy profiles of atomic conformational transition intermediates of adenylate kinase.

    Science.gov (United States)

    Feng, Yaping; Yang, Lei; Kloczkowski, Andrzej; Jernigan, Robert L

    2009-11-15

    The elastic network interpolation (ENI) (Kim et al., Biophys J 2002;83:1620-1630) is a computationally efficient and physically realistic method to generate conformational transition intermediates between two forms of a given protein. However it can be asked whether these calculated conformations provide good representatives for these intermediates. In this study, we use ENI to generate conformational transition intermediates between the open form and the closed form of adenylate kinase (AK). Based on C(alpha)-only intermediates, we construct atomic intermediates by grafting all the atoms of known AK structures onto the C(alpha) atoms and then perform CHARMM energy minimization to remove steric conflicts and optimize these intermediate structures. We compare the energy profiles for all intermediates from both the CHARMM force-field and from knowledge-based energy functions. We find that the CHARMM energies can successfully capture the two energy minima representing the open AK and closed AK forms, while the energies computed from the knowledge-based energy functions can detect the local energy minimum representing the closed AK form and show some general features of the transition pathway with a somewhat similar energy profile as the CHARMM energies. The combinatorial extension structural alignment (Shindyalov et al., 1998;11:739-747) and the k-means clustering algorithm are then used to show that known PDB structures closely resemble computed intermediates along the transition pathway.

  8. Mass-energy correlation measurements for /sup 252/Cf spontaneous fission

    Energy Technology Data Exchange (ETDEWEB)

    Sicre, A.; Barreau, G.; Caitucoli, F.; Doan, T.P.; Leroux, B.; Martinez, G.; Asghar, M.; Benfoughal, T.

    1985-01-01

    Fragment-mass and kinetic energy distribution measurements for /sup 252/Cf(sf) have been extended to the far-out asymmetric low yield fission region up to Msub(H) = 190 compared with the existing data that go up to Msub(H) approximately 168. The mass yield Y(M) shows an important enhancement for Msub(H) >= 176. The (M), sigmasub(Esub(K))(M) and, to a lesser extent, Y(M) distributions show strong and correlated amplitude fluctuations for Msub(H) >= 170. These data indicate strong and rapid changes in deformation of the nascent fragments. These structures are discussed in terms of the static macro-microscopic potential energy calculations. Several spherical and deformed shells are involved to stabilize the light fragment and especially the proton spherical shell Z = 28. So it is possible to observe very rich neutron nuclei like /sub 28//sup 73/Ni. Furthermore we select small excitation energy events (E* = Qsub(R) - Esub(KT) <= 8 MeV). The distribution Y(M) for these nearly cold fragmentations is dominated by the strong neutron deformed shell N = 88 and shows an important charge odd-even effect.

  9. ND:GLASS LASER DESIGN FOR LASER ICF FISSION ENERGY (LIFE)

    Energy Technology Data Exchange (ETDEWEB)

    Caird, J A; Agrawal, V; Bayramian, A; Beach, R; Britten, J; Chen, D; Cross, R; Ebbers, C; Erlandson, A; Feit, M; Freitas, B; Ghosh, C; Haefner, C; Homoelle, D; Ladran, T; Latkowski, J; Molander, W; Murray, J; Rubenchik, S; Schaffers, K; Siders, C W; Stappaerts, E; Sutton, S; Telford, S; Trenholme, J; Barty, C J

    2008-10-28

    We have developed preliminary conceptual laser system designs for the Laser ICF (Inertial Confinement Fusion) Fission Energy (LIFE) application. Our approach leverages experience in high-energy Nd:glass laser technology developed for the National Ignition Facility (NIF), along with high-energy-class diode-pumped solid-state laser (HEC-DPSSL) technology developed for the DOE's High Average Power Laser (HAPL) Program and embodied in LLNL's Mercury laser system. We present laser system designs suitable for both indirect-drive, hot spot ignition and indirect-drive, fast ignition targets. Main amplifiers for both systems use laser-diode-pumped Nd:glass slabs oriented at Brewster's angle, as in NIF, but the slabs are much thinner to allow for cooling by high-velocity helium gas as in the Mercury laser system. We also describe a plan to mass-produce pump-diode lasers to bring diode costs down to the order of $0.01 per Watt of peak output power, as needed to make the LIFE application economically attractive.

  10. To fission or not to fission

    CERN Document Server

    Pomorski, Krzysztof; Ivanyuk, Fedir A

    2016-01-01

    The fission-fragments mass-yield of 236U is obtained by an approximate solution of the eigenvalue problem of the collective Hamiltonian that describes the dynamics of the fission process whose degrees of freedom are: the fission (elongation), the neck and the mass-asymmetry mode. The macroscopic-microscopic method is used to evaluate the potential energy surface. The macroscopic energy part is calculated using the liquid drop model and the microscopic corrections are obtained using the Woods-Saxon single-particle levels. The four dimensional modified Cassini ovals shape parametrization is used to describe the shape of the fissioning nucleus. The mass tensor is taken within the cranking-type approximation. The final fragment mass distribution is obtained by weighting the adiabatic density distribution in the collective space with the neck-dependent fission probability. The neck degree of freedom is found to play a significant role in determining that final fragment mass distribution.

  11. Calorimetria nucleare in collisioni tra ioni pesanti ad energie intermedie

    Science.gov (United States)

    Spezzi, L.

    2002-07-01

    Nel presente lavoro di tesi ci si e' occupati di uno studio sistematico di misure di temperatura ed energia di eccitazione in sistemi nucleari formati in reazioni tra ioni pesanti ad energie intermedie. La temperatura a stata misurata tramite due diversi metodi: rapporto tra le rese di isotopi che differiscono di uno stesso numero di nucleoni ( d/t-3He/4He , 3He/4He -6Li/7Li) - temperatura isotopica -, e rapporto tra le popolazioni degli stati eccitati in frammenti instabili (5Li e 6Li) che decadono in particelle leggere in coincidenza - temperatura di emissione. Le misure in esame sono state effettuate presso i Laboratori Nazionali del Sud per i sistemi 93Nb+93Nb, 93Nb+116,124Sn, 116,120Sn+116,124Sn e 116Sn+93Nb ad energie comprese tra 17 e 40 A MeV. L'apparato di rivelazione era costituito da un odoscopio ad alta granularite (96 telescopi Si (50micron)-Si(300micron)-CsI(Tl) ) e basse soglie di rivelazione, utilizzato sia per identificare risonanze in frammenti eccitati che per misure di rese di isotopi di frammenti con 2<=Z<=6, e dal multirivelatore FIASCO che, grazie alla misura contemporanea di posizione e tempo di volo dei frammenti provenienti dal proiettile (PLF - Projectile Like Fragments) e dal bersaglio (TLF - Target Like Fragment), e' stato utilizzato per misurare direttamente l'energia di eccitazione del sistema in studio. Analisi precedenti, condotte nell'ambito di varie collaborazioni, hanno messo in evidenza la possible esistenza di una transizione di fase liquido-gas del primo ordine nella materia nucleare. In tale contesto, ci siamo occupati di una verifica della curva calorica nucleare, ovvero della correlazione esistente fra temperatura ed energia di eccitazione del sistema, indagando, nel contempo, sulla sua dipendenza dalla massa del sistema che si frammenta. Si e' effettuato, inoltre, un confronto fra i due diversi metodi di misura della temperatura (temperatura isotopica e di emissione): l'andamento plateau-like della curva calorica e' stato

  12. Mass and nuclear charge yields for sup 237 Np(2n sub th ,f) at different fission fragment kinetic energies

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, G.; Barreau, G.; Sicre, A.; Doan, T.P.; Audouard, P.; Leroux, B. (CEA Centre d' Etudes Nucleaires de Bordeaux-Gradignan, 33 - Gradignan (France)); Arafa, W.; Brissot, R.; Bocquet, J.P. (Grenoble-1 Univ., 38 (France). Inst. des Sciences Nucleaires); Faust, H. (Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)); Koczon, P.; Mutterer, M. (Technische Hochschule Darmstadt (Germany, F.R.). Inst. fuer Kernphysik); Goennenwein, F. (Tuebingen Univ. (Germany, F.R.). Physikalisches Inst.); Asghar, M. (Universite des Sciences et de la Technologie Houari Boumediene, Algiers (Algeria). Inst. de Physique); Quade, U.; Rudolph, K. (Muenchen Univ. (Germany, F.R.)); Engelhardt, D. (Karlsruhe Univ. (T.H.) (Germany, F.R.)); Piasecki, E. (Warsaw Univ. (Poland))

    1990-09-03

    The recoil mass separator LOHENGRIN of the Laue-Langevin Institute Grenoble has been used to measure for the first time, the yields of light fission fragments from the fissioning system: {sub 93}{sup 239}Np; this odd-Z nucleus is formed after double thermal neutron capture in a {sub 93}{sup 237}Np target. The mass distributions were measured for different kinetic energies between 92 and 115.5 MeV, but the nuclear charge distributions were determined only up to 112 MeV. These distributions are compared to the distributions obtained for the even-even system {sub 94}{sup 240}Pu. At high kinetic energy, the mass distribution shows a prominent peak around mass number A{sub L}=106. These cold fragmentations are discussed in terms of a calculation based on a scission point model extrapolated to the cold fission case. As expected for an odd-Z fissioning nucleus, the nuclear charge distributions do not reveal any odd-even effect. The global neutron odd-even effect is found to be (8.1{plus minus}1.5)%. A simple model has been used to show that most of the neutron odd-even effect results from prompt neutron evaporation from the fragments. (orig.).

  13. Microscopic description of fission in neutron-rich plutonium isotopes with the Gogny-D1M energy density functional

    CERN Document Server

    Rodriguez-Guzman, R

    2014-01-01

    The most recent parametrization D1M of the Gogny energy density functional is used to describe fission in the isotopes $^{232-280}$ Pu. We resort to the methodology introduced in our previous studies [Phys. Rev. C \\textbf{88}, 054325 (2013) and Phys. Rev. C \\textbf {89}, 054310 (2014)] to compute the fission paths, collective masses and zero point quantum corrections within the Hartree-Fock-Bogoliubov framework. The systematics of the spontaneous fission half-lives t$_{SF}$, masses and charges of the fragments in Plutonium isotopes is analyzed and compared with available experimental data. We also pay attention to isomeric states, the deformation properties of the fragments as well as to the competition between the spontaneous fission and $\\alpha$-decay modes. The impact of pairing correlations on the predicted t$_{SF}$ values is demonstrated with the help of calculations for $^{232-280}$Pu in which the pairing strengths of the Gogny-D1M energy density functional are modified by 5 $\\%$ and 10 $\\%$, respective...

  14. High-energy Neutron-induced Fission Cross Sections of Natural Lead and Bismuth-209

    CERN Document Server

    Tarrio, D; Carrapico, C; Eleftheriadis, C; Leeb, H; Calvino, F; Herrera-Martinez, A; Savvidis, I; Vlachoudis, V; Haas, B; Koehler, P; Vannini, G; Oshima, M; Le Naour, C; Gramegna, F; Wiescher, M; Pigni, M T; Audouin, L; Mengoni, A; Quesada, J; Becvar, F; Plag, R; Cennini, P; Mosconi, M; Rauscher, T; Couture, A; Capote, R; Sarchiapone, L; Vlastou, R; Domingo-Pardo, C; Dillmann, I; Pavlopoulos, P; Karamanis, D; Krticka, M; Jericha, E; Ferrari, A; Martinez, T; Trubert, D; Oberhummer, H; Karadimos, D; Plompen, A; Isaev, S; Terlizzi, R; Cortes, G; Cox, J; Cano-Ott, D; Pretel, C; Colonna, N; Berthoumieux, E; Vaz, P; Heil, M; Lopes, I; Lampoudis, C; Walter, S; Calviani, M; Gonzalez-Romero, E; Embid-Segura, M; Stephan, C; Igashira, M; Papachristodoulou, C; Aerts, G; Tavora, L; Berthier, B; Rudolf, G; Andrzejewski, J; Villamarin, D; Ferreira-Marques, R; Tain, J L; O'Brien, S; Reifarth, R; Kadi, Y; Neves, F; Poch, A; Kerveno, M; Rubbia, C; Lazano, M; Dahlfors, M; Wisshak, K; Salgado, J; Dridi, W; Ventura, A; Andriamonje, S; Assimakopoulos, P; Santos, C; Voss, F; Ferrant, L; Patronis, N; Chiaveri, E; Guerrero, C; Perrot, L; Vicente, M C; Lindote, A; Praena, J; Baumann, P; Kappeler, F; Rullhusen, P; Furman, W; David, S; Marrone, S; Tassan-Got, L; Gunsig, F; Alvarez-Velarde, F; Massimi, C; Mastinu, P; Pancin, J; Papadopoulos, C; Tagliente, G; Haight, R; Chepel, V; Kossionides, E; Badurek, G; Marganiec, J; Lukic, S; Pavlik, A; Goncalves, I; Duran, I; Alvarez, H; Abbondanno, U; Fujii, K; Milazzo, P M; Moreau, C

    2011-01-01

    The CERN Neutron Time-Of-Flight (n\\_TOF) facility is well suited to measure small neutron-induced fission cross sections, as those of subactinides. The cross section ratios of (nat)Pb and (209)Bi relative to (235)U and (238)U were measured using PPAC detectors. The fragment coincidence method allows to unambiguously identify the fission events. The present experiment provides the first results for neutron-induced fission up to 1 GeV for (nat)Pb and (209)Bi. A good agreement with previous experimental data below 200 MeV is shown. The comparison with proton-induced fission indicates that the limiting regime where neutron-induced and proton-induced fission reach equal cross section is close to 1 GeV.

  15. Comparative evaluation of solar, fission, fusion, and fossil energy resources. Part 1: Solar energy

    Science.gov (United States)

    Williams, J. R.

    1974-01-01

    The utilization of solar energy to meet the energy needs of the U.S. is discussed. Topics discussed include: availability of solar energy, solar energy collectors, heating for houses and buildings, solar water heater, electric power generation, and ocean thermal power.

  16. Primary photodissociation pathways of epichlorohydrin and analysis of the C-C bond fission channels from an O((3)P)+allyl radical intermediate.

    Science.gov (United States)

    Fitzpatrick, Benjamin L; Alligood, Bridget W; Butler, Laurie J; Lee, Shih-Huang; Lin, Jim Jr-Min

    2010-09-01

    This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H(2)COCH)CH(2)Cl. The three dominant photoproduct channels analyzed are c-(H(2)COCH)CH(2)+Cl, c-(H(2)COCH)+CH(2)Cl, and C(3)H(4)O+HCl. In the second channel, the c-(H(2)COCH) photofission product is a higher energy intermediate on C(2)H(3)O global potential energy surface and has a small isomerization barrier to vinoxy. The resulting highly vibrationally excited vinoxy radicals likely dissociate to give the observed signal at the mass corresponding to ketene, H(2)CCO. The final primary photodissociation pathway HCl+C(3)H(4)O evidences a recoil kinetic energy distribution similar to that of four-center HCl elimination in chlorinated alkenes, so is assigned to production of c-(H(2)COC)=CH(2); the epoxide product is formed with enough vibrational energy to isomerize to acrolein and dissociate. The paper then analyzes the dynamics of the C(3)H(5)O radical produced from C-Cl bond photofission. When the epoxide radical photoproduct undergoes facile ring opening, it is the radical intermediate formed in the O((3)P)+allyl bimolecular reaction when the O atom adds to an end C atom. We focus on the HCO+C(2)H(4) and H(2)CO+C(2)H(3) product channels from this radical intermediate in this report. Analysis of the velocity distribution of the momentum-matched signals from the HCO+C(2)H(4) products at m/e=29 and 28 shows that the dissociation of the radical intermediate imparts a high relative kinetic energy, peaking near 20 kcal/mol, between the products. Similarly, the energy imparted to relative kinetic energy in the H(2)CO+C(2)H(3) product channel of the O((3)P)+allyl radical intermediate also peaks at high-recoil kinetic energies, near 18 kcal/mol. The strongly forward-backward peaked angular distributions and the high kinetic energy release result from tangential recoil during the dissociation of highly rotationally excited nascent radicals formed photolytically in this

  17. NEUTRON CROSS SECTION EVALUATIONS OF FISSION PRODUCTS BELOW THE FAST ENERGY REGION

    Energy Technology Data Exchange (ETDEWEB)

    OH,S.Y.; CHANG,J.; MUGHABGHAB,S.

    2000-05-11

    Neutron cross section evaluations of the fission-product isotopes, {sup 95}Mo, {sup 99}Tc, {sup 101}Ru, {sup 103}Rh, {sup 105}Pd, {sup 109}Ag, {sup 131}Xe, {sup 133}Cs, {sup 141}Pr, {sup 141}Nd, {sup 147}Sm, {sup 149}Sm, {sup 150}Sm, {sup 151}Sm, {sup 152}Sm, {sup 153}Eu, {sup 155}Gd, and {sup 157}Gd were carried out below the fast neutron energy region within the framework of the BNL-KAERI international collaboration. In the thermal energy region, the energy dependence of the various cross-sections was calculated by applying the multi-level Breit-Wigner formalism. In particular, the strong energy dependence of the coherent scattering lengths of {sup 155}Gd and {sup 157}Gd were determined and were compared with recent calculations of Lynn and Seeger. In the resonance region, the recommended resonance parameters, reported in the BNL compilation, were updated by considering resonance parameter information published in the literature since 1981. The s-wave and, if available, p-wave reduced neutron widths were analyzed in terms of the Porter-Thomas distribution to determine the average level spacings and the neutron strength functions. Average radiative widths were also calculated from measured values of resolved energy resonances. The average resonance parameters determined in this study were compared with those in the BNL and other compilations, as well as the ENDF/B-VI, JEF-2.2, and JENDL-3.2 data libraries. The unresolved capture cross sections of these isotopes, computed with the determined average resonance parameters, were compared with measurements, as well as the ENDF/B-VI evaluations. To achieve agreement with the measurements, in a few cases minor adjustments in the average resonance parameters were made. Because of astrophysical interest, the Maxwellian capture cross sections of these nuclides at a neutron temperature of 30 keV were computed and were compared with other compilations and evaluations.

  18. Student Experiments in Spontaneous Fission.

    Science.gov (United States)

    Becchetti, F. D.; Ying, J. S.

    1981-01-01

    Advanced undergraduate experiments utilizing a commercially available, thin spontaneous fission source are described, including studies of the energy and mass distribution of the fission fragments and their energy and angular correlation. The experiments provide a useful introduction to fission, nuclear mass equations, heavy-ion physics, and…

  19. Complex fission phenomena

    Science.gov (United States)

    Poenaru, D. N.; Gherghescu, R. A.; Greiner, W.

    2005-01-01

    Complex fission phenomena are studied in a unified way. Very general reflection asymmetrical equilibrium (saddle point) nuclear shapes are obtained by solving an integro-differential equation without being necessary to specify a certain parametrization. The mass asymmetry in binary cold fission of Th and U isotopes is explained as the result of adding a phenomenological shell correction to the liquid drop model deformation energy. Applications to binary, ternary, and quaternary fission are outlined.

  20. Mass-energy distribution of fragments in Langevin dynamics of fission induced by heavy ions

    Directory of Open Access Journals (Sweden)

    Vanin D. V.

    2012-12-01

    Full Text Available Four-dimensional Langevin equation was employed to calculate mass-energy distributions of fission fragments of highly excited compound nuclei. The research took into account not only three shape collective coordinates introduced on the basis of {c,h,α}-parametrization but also orientation degree of freedom (K-state— spin about the symmetry axis. Overdamped Langevin equation was used to describe the evolution of the K-state. Friction tensor was calculated using the “wall+window” model of the modified one-body dissipation mechanism with a reduction coeffcient from the “wall” formula ks. The calculations have been performed with ks = 0:25 and ks = 1:0. To learn more about the role of the dissipation effects the calculations have also been done with use of the chaoticity measure of nucleon movements in the nuclear shape configuration as ks parameter. Calculations were performed for the large number of compound nuclei with Z2/A parameter in the range 21 ≤ Z2/A ≤ 44. The goal was to study the mass-energy distributions not only for heavy nuclei but also for light nuclei close to the Businaro-Gallone point. Mass-energy distributions and variances of the mass fragments are well reproduced in the applied calculations for all considered compound nuclei. It was shown that inclusion of the K-state in the dynamical model produces considerable increase of the mass and energy variances. Inclusion of the chaoticity measure to the friction tensor provides a better agreement with the experiment results on mass variances.

  1. Sustainable and safe nuclear fission energy technology and safety of fast and thermal nuclear reactors

    CERN Document Server

    Kessler, Günter

    2012-01-01

    Unlike existing books of nuclear reactor physics, nuclear engineering and nuclear chemical engineering this book covers a complete description and evaluation of nuclear fission power generation. It covers the whole nuclear fuel cycle, from the extraction of natural uranium from ore mines, uranium conversion and enrichment up to the fabrication of fuel elements for the cores of various types of fission reactors. This is followed by the description of the different fuel cycle options and the final storage in nuclear waste repositories. In addition the release of radioactivity under normal and possible accidental conditions is given for all parts of the nuclear fuel cycle and especially for the different fission reactor types.

  2. Energy Dependence of Neutron-Induced Fission Product Yields of 235U, 238U and 239Pu Between 0.5 and 14.8 MeV

    Science.gov (United States)

    Gooden, Matthew; Tornow, Werner; Tonchev, Anton; Vieira, Dave; Wilhelmy, Jerry; Arnold, Charles; Fowler, Malcolm; Stoyer, Mark

    2014-09-01

    Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements have been performed. The energy dependence of a number of cumulative fission products between 0.5 and 14.8 MeV have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of activation utilizing specially designed dual-fission chambers and γ-ray counting. The dual-fission chambers are back-to-back ionization chambers encasing a target with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the fission rate in the activation target with no reference to the fission cross-section, reducing uncertainties. γ-ray counting was performed on well-shield HPGe detectors over a period of 2 months per activation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 4.6 and 14.8 MeV.

  3. Monte-Carlo simulation for fragment mass and kinetic energy distributions from neutron induced fission of 235U

    CERN Document Server

    Montoya, M; Rojas, J

    2007-01-01

    The mass and kinetic energy distribution of nuclear fragments from thermal neutron induced fission of 235U have been studied using a Monte-Carlo simulation. Besides reproducing the pronounced broadening on the standard deviation of the final fragment kinetic energy distribution $\\sigma_{e}(m)$ around the mass number m = 109, our simulation also produces a second broadening around m = 125, that is in agreement with the experimental data obtained by Belhafaf et al. These results are consequence of the characteristics of the neutron emission, the variation in the primary fragment mean kinetic energy and the yield as a function of the mass.

  4. Spontaneous fission properties of superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Hessberger, F.P. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Helmholtz-Institut Mainz, Mainz (Germany)

    2017-04-15

    Spontaneous fission properties of transuranium isotopes are reviewed. Specific emphasis was laid on brief historical overviews of theoretical descriptions and experimental determination of basic properties as spontaneous fission half-lives, fission barriers, or total kinetic energy release in fission. Experimental spontaneous fission half-lives are compared with the results of recent theoretical predictions. Hindrance factors for spontaneous fission of odd-mass nuclei are discussed in context with the configuration (spin, parity) of the fissioning states and the change in energy of single particle levels at deformation. Kinetic energy release and mass distributions are discussed in the context of different fission modes, as symmetric and asymmetric or fission from elongated or compact shapes of the nascent fission fragments. An overview of recent fission barrier calculations of superheavy elements on the basis of macroscopic-microscopic models or self-consistent calculations is given, and the results are compared for selected examples. (orig.)

  5. 1: the atom. 2: radioactivity. 3: man and radiations. 4: the energy. 5: nuclear energy: fusion and fission. 6: the operation of a nuclear reactor. 7: the nuclear fuel cycle; 1: l'atome. 2: la radioactivite. 3: l'homme et les rayonnements. 4: l'energie. 5: l'energie nucleaire: fusion et fission. 6: le fonctionnement d'un reacteur nucleaire. 7: le cycle du combustible nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-07-01

    This series of 7 digest booklets present the bases of the nuclear physics and of the nuclear energy: 1 - the atom (structure of matter, chemical elements and isotopes, the four fundamental interactions, nuclear physics); 2 - radioactivity (definition, origins of radioelements, applications of radioactivity); 3 - man and radiations (radiations diversity, biological effects, radioprotection, examples of radiation applications); 4 - energy (energy states, different forms of energy, characteristics); 5 - nuclear energy: fusion and fission (nuclear energy release, thermonuclear fusion, nuclear fission and chain reaction); 6 - operation of a nuclear reactor (nuclear fission, reactor components, reactor types); 7 - nuclear fuel cycle (nuclear fuel preparation, fuel consumption, reprocessing, wastes management). (J.S.)

  6. Fission and Properties of Neutron-Rich Nuclei - Proceedings of the Second International Conference

    Science.gov (United States)

    Hamilton, J. H.; Phillips, W. R.; Carter, H. K.

    Stability, Fission Barrier and Nuclear Structure of the Z = 102 Isotope 254No * Neutron Capture on Radioactive Targets: Probing the S-Process * Angular Momentum Generation in Spontaneous Fission Fragments Without Thermal Excitation of Collective Modes * First Excited States in Neutron-Rich Neon and Sodium Isotopes * Production and Identification of New Heavy Neutron-Rich Isotopes * The Munich Accelerator for Fission Fragments MAFF, the Recycling of Radioactive Beams and Superheavy Elements * SIRIUS: A UK Facility to Provide Parallel Radioactive Beams for Research * Spectroscopy of Halo Nuclei From Reaction Measurements * Possibilities for Experiments with Neutron-Rich Beams in Nuclear Astrophysics * Superheavy Nuclei Revisited * Prospects for the Production of Neutron-Rich Nuclei by Relativistic Beams * Coulomb Dissociation of 19C and its Halo Structure * New Results on the Role of Shell Effects in Nuclear Fission From Experiments with Secondary Beams * How to Interpret the Correlations Preceding Spontaneous Fission Events Observed in Reactions of 48Ca with the Heaviest Actinide Targets * Charge and Mass Distributions of Fission Fragments From Intermediate Energy Collisions of 238U Projectiles. Generation of Very Neutron-Rich Nuclei * Fission Modes in 238U + d Reaction at Intermediate Energy * SU(3) Dynamical Symmetry and Odd-Even (ΔL = 1) Staggering in Heavy Deformed Nuclei * Deformation of Fragments with A ≃ 130 in Two Mode Fission * List of Participants

  7. Neutron emission effects on final fragments mass and kinetic energy distribution from low energy fission of {sup 234}U

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, M.; Rojas, J. [Instituto Peruano de Energia Nuclear, Av. Canada 1470, Lima 41 (Peru); Lobato, I. [Facultad de Ciencias, Universidad Nacional de Ingenieria, Av. Tupac Amaru 210, Apartado Postal 31-139, Lima (Peru)]. e-mail: mmontoya@ipen.gob.pe

    2008-07-01

    The standard deviation of the final kinetic energy distribution ({sigma}{sub e}) as a function of mass of final fragments (m) from low energy fission of {sup 234}U, measured with the Lohengrin spectrometer by Belhafaf et al., presents a peak around m = 109 and another around m = 122. The authors attribute the first peak to the evaporation of a large number of neutrons around the corresponding mass number, i.e. there is no peak on the standard deviation of the primary kinetic energy distribution ({sigma}{sub E}) as a function of primary fragment mass (A). The second peak is attributed to a real peak on {sigma}{sub E}(A). However, theoretical calculations related to primary distributions made by H.R. Faust and Z. Bao do not suggest any peak on {sigma}{sub E}(A). In order to clarify this apparent controversy, we have made a numerical experiment in which the masses and the kinetic energy of final fragments are calculated, assuming an initial distribution of the kinetic energy without structures on the standard deviation as function of fragment mass. As a result we obtain a pronounced peak on {sigma}{sub e} (m) curve around m = 109, a depletion from m = 121 to m = 129, and an small peak around m = 122, which is not as great as that measured by Belhafaf et al. Our simulation also reproduces the experimental results on the yield of the final mass Y(m), the average number of emitted neutrons as a function of the provisional mass (calculated from the values of the final kinetic energy of the complementary fragments) and the average value of fragment kinetic energy as a function of the final mass. From our results we conclude that there are no peaks on the {sigma}{sub E} (A) curve, and the observed peaks on {sigma}{sub e} (m) are due to the emitted neutron multiplicity and the variation of the average fragment kinetic energy as a function of primary fragment mass. (Author)

  8. Excitation energy dependence of fragment-mass distributions from fission of 180,190Hg formed in fusion reactions of 36Ar + 144,154Sm

    Directory of Open Access Journals (Sweden)

    K. Nishio

    2015-09-01

    Full Text Available Mass distributions of fission fragments from the compound nuclei 180Hg and 190Hg formed in fusion reactions 36Ar + 144Sm and 36Ar + 154Sm, respectively, were measured at initial excitation energies of E⁎(Hg180=33–66 MeV and E⁎(Hg190=48–71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses A¯L/A¯H=79/101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β+/EC-delayed fission of 180Tl, from our earlier ISOLDE(CERN experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of A¯L/A¯H=83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.

  9. Fission Measurements with Dance

    Science.gov (United States)

    Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Keksis, A. L.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Agvaanluvsan, U.; Dashdorj, D.; Macri, R. A.; Parker, W. E.; Wilk, P. A.; Wu, C. Y.; Becker, J. A.; Angell, C. T.; Tonchev, A. P.; Baker, J. D.

    2008-08-01

    Neutron capture cross section measurements on actinides are complicated by the presence of neutron-induced fission. An efficient fission tagging detector used in coincidence with the Detector for Advanced Neutron Capture Experiments (DANCE) provides a powerful tool in undertaking simultaneous measurements of (n,γ) and (n,f) cross sections. Preliminary results on 235U(n,γ) and (n,f) and 242mAm(n,f) cross sections measured with DANCE and a custom fission-tagging parallel plate avalanche counter (PPAC) are presented. Additional measurements of γ-ray cluster multiplicity distributions for neutron-induced fission of 235U and 242mAm and spontaneous fission of 252Cf are shown, as well as γ-ray energy and average γ-ray energy distributions.

  10. Statistical and off-equilibrium production of fragments in heavy ion collisions at intermediate energies; Production statistique et hors-equilibre de fragments dans les collisions d`ions lourdes aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Bocage, Frederic [Lab. de Physique Corpusculaire, Caen Univ., 14 - Caen (France)

    1998-12-15

    The study of reaction products, fragments and light charged particles, emitted during heavy-ion collisions at intermediate energies has shown the dominant binary dissipative character of the reaction, which is persisting for almost all impact parameters. However, in comparison with this purely binary process, an excess of nuclear matter is observed in-between the quasi-projectile and the quasi-target. To understand the mechanisms producing such an excess, this work studies more precisely the breakup in two fragments of the quasi-projectile formed in Xe+Sn, from 25 to 50 MeV/u, and Gd+C and Gd+U at 36 MeV/u. The data were obtained during the first INDRA experiment at GANIL. The angular distributions of the two fragments show the competition between statistical fission and non-equilibrated breakup of the quasi-projectile. In the second case, the two fragments are aligned along the separation axis of the two primary partners. The comparison of the fission directions and probabilities with statistical models allows us to measure the fission time, as well as the angular momentum, temperature and size of the fissioning residue. The relative velocities are compatible with Coulomb and thermal effects in the case of statistical fission and are found much higher for the breakup of a non-equilibrated quasi-projectile, which indicates that the projectile was deformed during interaction with the target. Such deformations should be compared with dynamical calculations in order to constrain the viscosity of nuclear matter and the parameters of the nucleon-nucleon interaction, (author) 148 refs., 77 figs., 11 tabs.

  11. Energy dependence of fission product yields from 235U, 238U, and 239Pu with monoenergetic neutrons between thermal and 14.8 MeV

    Science.gov (United States)

    Gooden, Matthew; Arnold, Charles; Bhike, Megha; Bredeweg, Todd; Fowler, Malcolm; Krishichayan; Tonchev, Anton; Tornow, Werner; Stoyer, Mark; Vieira, David; Wilhelmy, Jerry

    2017-09-01

    Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements has been performed. The energy dependence of a number of cumulative fission product yields (FPY) have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of fission counting using specially designed dual-fission chambers and γ-ray counting. Each dual-fission chamber is a back-to-back ionization chamber encasing an activation target in the center with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the total number of fissions in the activation target with no reference to the fission cross-section, thus reducing uncertainties. γ-ray counting of the activation target was performed on well-shielded HPGe detectors over a period of two months post irradiation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 3.6, 4.6, 5.5, 7.5, 8.9 and 14.8 MeV. Preliminary results from thermal irradiations at the MIT research reactor will also be presented and compared to present data and evaluations. This work was performed under the auspices of the U.S. Department of Energy by Los Alamos National Security, LLC under contract DE-AC52-06NA25396, Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and by Duke University and Triangle Universities Nuclear Laboratory through NNSA Stewardship Science Academic Alliance grant No. DE-FG52-09NA29465, DE-FG52-09NA29448 and Office of Nuclear Physics Grant No. DE-FG02-97ER41033.

  12. Determination of Fission Product Yields of 235U, 238U and 239Pu for Neutron Energies from 0.5 to 14.8 MeV

    Science.gov (United States)

    Gooden, Matthew; Arnold, Charles; Becker, John; Bhatia, Chitra; Bhike, Megha; Fowler, Malcolm; Howell, Calvin; Kelley, John; Stoyer, Mark; Tonchev, Anton; Tornow, Werner; Vieira, Dave; Wilhelmy, Jerry

    2014-03-01

    A joint TUNL-LANL-LLNL collaboration has been formed to study the issue of possible energy dependences for certain fission product isotopes. Work has been carried out at the TUNL 10 MV Tandem accelerator which produces nearly mono-energetic neutrons via either 2H(d,n)3He,3H(d,n)4He,or3H(p,n)3He reactions. Three dual fission ionization chambers dedicated to 235U, 238U and 239Pu thick target foils and thin monitor foils respectively, were exposed to the neutron beams. After irradiation, thick target foils were gamma counted over a period of 1-2 months and characteristic gamma rays from fission products were recorded using HPGe detectors at TUNL's low background counting area. Using the dual fission chambers, relative fission product yield were determined at a high precision of 2-3 % as well as absolute fission product yields at a lower precision of 5-6 %. Preliminary results will be presented for a number of fission product isotopes over the incident neutron energy range of 0.5 to 14.8 MeV.

  13. Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering

    Science.gov (United States)

    Lukman, Steven; Chen, Kai; Hodgkiss, Justin M.; Turban, David H. P.; Hine, Nicholas D. M.; Dong, Shaoqiang; Wu, Jishan; Greenham, Neil C.; Musser, Andrew J.

    2016-12-01

    Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics.

  14. Assessing the role of the (n, γ f process in the low-energy fission of actinides

    Directory of Open Access Journals (Sweden)

    Talou Patrick

    2016-01-01

    Full Text Available We review the role of the (n, γ f process in the low-energy neutron-induced fission reaction of 239Pu. Recent measurements of the average total γ-ray energy released in this reaction were performed with the Detector for Advanced Neutron Capture Experiments (DANCE at Los Alamos. Significant fluctuations of this quantity in the resonance region below 100 eV can be interpreted by invoking the presence of the indirect (n, γ f process. Modern calculations of the probability for such an event to occur are presented.

  15. Energy Technology Programmes 1993-1998. Intermediate report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    The Tekes energy technology research programmes were launched in 1993. The aim is to produce innovative solutions that are efficient, environmentally sound and widely - even globally - applicable. Now Tekes manages a total of 12 energy technology research programmed. Research programmed form a network linking academia and industry. Total funding for the energy technology programmed during the years 1993-1998 is estimated at some FIM 1.5 billion, about half of which will be put up by the Tekes and the rest by the industry. Funding by the Ministry of Trade and Industry covers the first full-scale applications (demonstrations) resulting from the research and development activities. Finnish technology is front-ranking in the efficient use of energy, combustion technology, renewable energy sources and environmental technology. In this report the results and the research activities of the separate programmes is presented and discussed

  16. Thermal fission rates with temperature dependent fission barriers

    Science.gov (United States)

    Zhu, Yi; Pei, J. C.

    2016-08-01

    Background: The fission processes of thermal excited nuclei are conventionally studied by statistical models which rely on inputs of phenomenological level densities and potential barriers. Therefore the microscopic descriptions of spontaneous fission and induced fission are very desirable for a unified understanding of various fission processes. Purpose: We propose to study the fission rates, at both low and high temperatures, with microscopically calculated temperature-dependent fission barriers and collective mass parameters. Methods: The fission barriers are calculated by the finite-temperature Skyrme-Hartree-Fock+BCS method. The mass parameters are calculated by the temperature-dependent cranking approximation. The thermal fission rates can be obtained by the imaginary free energy approach at all temperatures, in which fission barriers are naturally temperature dependent. The fission at low temperatures can be described mainly as a barrier-tunneling process. While the fission at high temperatures has to incorporate the reflection above barriers. Results: Our results of spontaneous fission rates reasonably agree with other studies and experiments. The temperature dependencies of fission barrier heights and curvatures have been discussed. The temperature dependent behaviors of mass parameters have also been discussed. The thermal fission rates from low to high temperatures with a smooth connection have been given by different approaches. Conclusions: Since the temperature dependencies of fission barrier heights and curvatures, and the mass parameters can vary rapidly for different nuclei, the microscopic descriptions of thermal fission rates are very valuable. Our studies without free parameters provide a consistent picture to study various fissions such as that in fast-neutron reactors, astrophysical environments, and fusion reactions for superheavy nuclei.

  17. Interactions of quarks and gluons with nuclei at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, A.H. [Columbia Univ., New York, NY (United States)

    1994-04-01

    Some processes involving the interaction of medium energy quarks and gluons with nuclear matter are described. Possible mechanisms for the A-dependence of the energy loss of leading protons produced in proton-nucleus collisions are given, and an experiment which may help to distinguish these mechanisms is described. A possible color transparency experiment at CEBAF is described. Experiments to measure energy loss of quarks in nuclear matter and the formation time of hadrons are discussed along with the possibilities of measuring {sigma}{sub J}/{psi} and {sigma}{sub {psi}{prime}} at CEBAF.

  18. The Complete Burning of Weapons Grade Plutonium and Highly Enriched Uranium with (Laser Inertial Fusion-Fission Energy) LIFE Engine

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Diaz de la Rubia, T; Moses, E

    2008-12-23

    The National Ignition Facility (NIF) project, a laser-based Inertial Confinement Fusion (ICF) experiment designed to achieve thermonuclear fusion ignition and burn in the laboratory, is under construction at the Lawrence Livermore National Laboratory (LLNL) and will be completed in April of 2009. Experiments designed to accomplish the NIF's goal will commence in late FY2010 utilizing laser energies of 1 to 1.3 MJ. Fusion yields of the order of 10 to 20 MJ are expected soon thereafter. Laser initiated fusion-fission (LIFE) engines have now been designed to produce nuclear power from natural or depleted uranium without isotopic enrichment, and from spent nuclear fuel from light water reactors without chemical separation into weapons-attractive actinide streams. A point-source of high-energy neutrons produced by laser-generated, thermonuclear fusion within a target is used to achieve ultra-deep burn-up of the fertile or fissile fuel in a sub-critical fission blanket. Fertile fuels including depleted uranium (DU), natural uranium (NatU), spent nuclear fuel (SNF), and thorium (Th) can be used. Fissile fuels such as low-enrichment uranium (LEU), excess weapons plutonium (WG-Pu), and excess highly-enriched uranium (HEU) may be used as well. Based upon preliminary analyses, it is believed that LIFE could help meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the nation's and world's stockpile of spent nuclear fuel and excess weapons materials. LIFE takes advantage of the significant advances in laser-based inertial confinement fusion that are taking place at the NIF at LLNL where it is expected that thermonuclear ignition will be achieved in the 2010-2011 timeframe. Starting from as little as 300 to 500 MW of fusion power, a single LIFE engine will be able to generate 2000 to 3000 MWt in steady state for periods of years to decades, depending on the nuclear fuel and engine configuration. Because the fission

  19. World Energy Data System (WENDS). Volume XI. Nuclear fission program summaries

    Energy Technology Data Exchange (ETDEWEB)

    1979-06-01

    Brief management and technical summaries of nuclear fission power programs are presented for nineteen countries. The programs include the following: fuel supply, resource recovery, enrichment, fuel fabrication, light water reactors, heavy water reactors, gas cooled reactors, breeder reactors, research and test reactors, spent fuel processing, waste management, and safety and environment. (JWR)

  20. Characteristic Dirac Signature in Elastic Proton Scattering at Intermediate Energies

    Science.gov (United States)

    Hynes, M. V.; Picklesimer, A.; Tandy, P. C.; Thaler, R. M.

    1984-03-01

    Nonrelativistic nucleon-nucleus first-order multiple-scattering calculations are extended to include virtual (Dirac) negative energy states of just the projectile. This effect may be thought of as virtual NN¯ pair production and annihilation in the field of the nucleus. This extension leads to a parameter-free Dirac description of the projectile in elastic proton scattering which produces a characteristic effect in spin observables over a wide range of energies which is in agreement with experiment. This Dirac signature is extremely stable with respect to uncertainties in the microscopic input.

  1. Stochastic approaches to dynamics of heavy ion collisions, the case of thermal fission

    Energy Technology Data Exchange (ETDEWEB)

    Boilley, D.; Abe, Y. [Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics; Suraud, E. [Universite Paul Sabatier, 31 - Toulouse (France). Lab. de Physique Quantique; Ayik, S. [Tennessee Technological Univ., Cookeville, TN (United States)

    1994-03-30

    In order to study the influence of fluctuations on various phenomena linked to heavy ion collisions, a Langevin equation has been derived from a microscopic model. Parameters entering this equation are completely determined from microscopic quantities characterizing nuclear matter. This equation has been applied to various phenomena at intermediate energies. This paper focuses on large amplitude motions and especially thermal fission. Fission rate is calculated and compared to experimental results.

  2. The nuclear spin response to intermediate energy protons

    Energy Technology Data Exchange (ETDEWEB)

    Baker, F.T. (Georgia Univ., Athens (USA)); Bimbot, L.; Djalali, C.; Morlet, M.; Willis, A. (Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire); Castel, B. (Queen' s Univ., Kingston, Ontario (Canada)); Fergerson, R.W.; Glashausser, C.; Green, A.; Beatty, D.; Cupps, V. (Rutgers - the State Univ., Piscataway, NJ (USA)); Hausser, O. (Simon Fraser Univ., Burnaby, British Columbia (Canada) British Columbia Univ., Vancouver (Canada). TRIUMF Facility); Hicks, K.; Miller, C.A.; Abegg, R.; Jackson, K.P.; Yen, S. (British Columbia Univ., Vancouver (Canada). TRIUMF Facility); Jones, K.; Smith, R.D. (Los Alamos National Lab., NM (USA)); Nanda, S.K. (Continuous Electron Beam Accelerator Facility, Newport News, VA (USA)); Vetterli, M.; Jeppeson, R. (Simon Fraser Univ., Burnaby, British Columbia (Canada)); Henderson, R. (British Columbia Univ., Vancouver (Canada). TRIUMF Facility Melbourne Univ., Parkville (Australia)); Lisantti, J. (Oregon Univ., Eugene (USA)); Sawafta, R. (A

    1990-03-22

    Measurements of the spin-flip probability S{sub nn} for inclusive inelastic proton scattering around 300 MeV from nuclei between {sup 12}C and {sup 90}Zr show that an enhanced spin response near 40 MeV excitation at q{proportional to}100 MeV/c is a general feature of nuclear structure. Data for {sup 40}Ca at 800 MeV confirm that the enhancement is not a peculiarity of 300 MeV scattering. In addition, measurements in {sup 44}Ca up to 75 MeV show that the enhancement cannot be attributed solely to a relatively narrow resonance. Continuum RPA calculations suggest that the enhancement is due to the exhaustion of most S=0 strength at lower energy and a shift of S=1 strength to higher energy. (orig.).

  3. Spin observables in deuteron proton radiative capture at intermediate energies

    Science.gov (United States)

    Mehmandoost-Khajeh-Dad, A. A.; Amir-Ahmadi, H. R.; Bacelar, J. C. S.; van den Berg, A. M.; Castelijns, R.; Deltuva, A.; van Garderen, E. D.; Glöckle, W.; Golak, J.; Kalantar-Nayestanaki, N.; Kamada, H.; Kiš, M.; Koohi-Fayegh-Dehkordi, R.; Löhner, H.; Mahjour-Shafiei, M.; Mardanpour, H.; Messchendorp, J. G.; Nogga, A.; Sauer, P.; Shende, S. V.; Skibinski, R.; Witała, H.; Wörtche, H. J.

    2005-06-01

    A radiative deuteron-proton capture experiment was carried out at KVI using polarized-deuteron beams at incident energies of 55, 66.5, and 90 MeV/nucleon. Vector and tensor-analyzing powers were obtained for a large angular range. The results are interpreted with the help of Faddeev calculations, which are based on modern two- and three-nucleon potentials. Our data are described well by the calculations, and disagree significantly with the observed tensor anomaly at RCNP.

  4. Charge Transfer and Ionization by Intermediate-Energy Heavy Ions

    Energy Technology Data Exchange (ETDEWEB)

    Toburen, L. H. [East Carolina University; McLawhorn, S. L. [East Carolina University; McLawhorn, R. A. [East Carolina University; Evans, N. L. [East Carolina University; Justiniano, E. L. B. [East Carolina University; Shinpaugh, J. L. [East Carolina University; Schultz, David Robert [ORNL; Reinhold, Carlos O [ORNL

    2006-11-01

    The use of heavy ion beams for microbeam studies of mammalian cell response leads to a need to better understand interaction cross sections for collisions of heavy ions with tissue constituents. For ion energies of a few MeV u-1 or less, ions capture electrons from the media in which they travel and undergo subsequent interactions as partially 'dressed' ions. For example, 16 MeV fluorine ions have an equilibrium charge of 7+, 32 MeV sulphur ions have an equilibrium charge of approx. 11+, and as the ion energies decrease the equilibrium charge decreases dramatically. Data for interactions of partially dressed ions are extremely rare, making it difficult to estimate microscopic patterns of energy deposition leading to damage to cellular components. Such estimates, normally obtained by Monte Carlo track structure simulations, require a comprehensive database of differential and total ionisation cross sections as well as charge transfer cross sections. To provide information for track simulation, measurement of total ionisation cross sections have been initiated at East Carolina University using the recoil ion time-of-flight method that also yields cross sections for multiple ionisation processes and charge transfer cross sections; multiple ionisation is prevalent for heavy ion interactions. In addition, measurements of differential ionisation cross sections needed for Monte Carlo simulation of detailed event-by-event particle tracks are under way. Differential, total and multiple ionisation cross sections and electron capture and loss cross sections measured for C+ ions with energies of 100 and 200 keV u-1 are described.

  5. Charge transfer and ionisation by intermediate-energy heavy ions.

    Science.gov (United States)

    Toburen, L H; McLawhorn, S L; McLawhorn, R A; Evans, N L; Justiniano, E L B; Shinpaugh, J L; Schultz, D R; Reinhold, C O

    2006-01-01

    The use of heavy ion beams for microbeam studies of mammalian cell response leads to a need to better understand interaction cross sections for collisions of heavy ions with tissue constituents. For ion energies of a few MeV u(-1) or less, ions capture electrons from the media in which they travel and undergo subsequent interactions as partially 'dressed' ions. For example, 16 MeV fluorine ions have an equilibrium charge of 7(+), 32 MeV sulphur ions have an equilibrium charge of approximately 11(+), and as the ion energies decrease the equilibrium charge decreases dramatically. Data for interactions of partially dressed ions are extremely rare, making it difficult to estimate microscopic patterns of energy deposition leading to damage to cellular components. Such estimates, normally obtained by Monte Carlo track structure simulations, require a comprehensive database of differential and total ionisation cross sections as well as charge transfer cross sections. To provide information for track simulation, measurement of total ionisation cross sections have been initiated at East Carolina University using the recoil ion time-of-flight method that also yields cross sections for multiple ionisation processes and charge transfer cross sections; multiple ionisation is prevalent for heavy ion interactions. In addition, measurements of differential ionisation cross sections needed for Monte Carlo simulation of detailed event-by-event particle tracks are under way. Differential, total and multiple ionisation cross sections and electron capture and loss cross sections measured for C(+) ions with energies of 100 and 200 keV u(-1) are described.

  6. Calculation of the intermediate energy activation cross section

    Energy Technology Data Exchange (ETDEWEB)

    Furihata, Shiori; Yoshizawa, Nobuaki [Mitsubishi Research Inst., Inc., Tokyo (Japan)

    1997-03-01

    We discussed the activation cross section in order to predict accurately the activation of soil around an accelerator with high energy and strong intensity beam. For the assessment of the accuracy of activation cross sections estimated by a numerical model, we compared the calculated cross section with various experimental data, for Si(p,x){sup 22}Na, Al(p,x){sup 22}Na, Fe(p,x){sup 22}Na, Si(p,x){sup 7}Be, O(p,x){sup 3}H, Al(p,x){sup 3}H and Si(p,x){sup 3}H reactions. We used three computational codes, i.e., quantum molecular dynamics (QMD) plus statistical decay model (SDM), HETC-3STEP and the semiempirical method developed by Silberberg et.al. It is observed that the codes are accurate above 1GeV, except for {sup 7}Be production. We also discussed the difference between the activation cross sections of proton- and neutron-induced reaction. For the incident energy at 40MeV, it is found that {sup 3}H production cross sections of neutron-induced reaction are ten times as large as those of proton-induced reaction. It is also observed that the choice of the activation cross sections seriously affects to the estimate of saturated radioactivity, if the maximum energy of neutron flux is below 100MeV. (author)

  7. Effect of transverse vibrations of fissile nuclei on the angular and spin distributions of low-energy fission fragments

    Science.gov (United States)

    Bunakov, V. E.; Kadmensky, S. G.; Lyubashevsky, D. E.

    2016-05-01

    It is shown that A. Bohr's classic theory of angular distributions of fragments originating from low-energy fission should be supplemented with quantum corrections based on the involvement of a superposition of a very large number of angular momenta L m in the description of the relative motion of fragments flying apart along the straight line coincidentwith the symmetry axis. It is revealed that quantum zero-point wriggling-type vibrations of the fissile system in the vicinity of its scission point are a source of these angular momenta and of high fragment spins observed experimentally.

  8. Evidence for a Novel Reaction Mechanism of a Prompt Shock-Induced Fission Following the Fusion of 78Kr and 40Ca Nuclei at E/A =10 MeV

    CERN Document Server

    Henry, E; Nyibule, S; Quinlan, M; Schroder, W U; Ademard, G; Amorini, F; Auditore, L; Beck, C; Berceanu, I; Bonnet, E; Borderie, B; Cardella, G; Chbihi, A; Colonna, M; De Filippo, E; DOnofrio, A; Frankland, J D; Geraci, E; La Guidara, E; La Commara, M; Lanzalone, G; Lautesse, P; Lebhertz, D; Neindre, N Le; Lombardo, I; Loria, D; Mazurek, K; Pagano, A; Papa, M; Piasecki, E; Pirrone, S; Politi, G; Porto, F; Rizzo, F; Rosato, E; Rusotto, P; Spadaccini, G; Trifiro, A; Trimarchi, M; Verde, G; Vigilante, M; Wieleczko, J P

    2014-01-01

    An analysis of experimental data from the inverse-kinematics ISODEC experiment on 78Kr+40Ca reaction at a bombarding energy of 10 AMeV has revealed signatures of a hitherto unknown reaction mechanism, intermediate between the classical damped binary collisions and fusion-fission, but also substantially different from what is being termed in the literature as fast fission or quasi fission. These signatures point to a scenario where the system fuses transiently while virtually equilibrating mass asymmetry and energy and, yet, keeping part of the energy stored in a collective shock-imparted and, possibly, angular momentum bearing form of excitation. Subsequently the system fissions dynamically along the collision or shock axis with the emerging fragments featuring a broad mass spectrum centered around symmetric fission, relative velocities somewhat higher along the fission axis than in transverse direction, and virtually no intrinsic spin. The class of massasymmetric fission events shows a distinct preference fo...

  9. Proton-deuteron radiative capture cross sections at intermediate energies

    CERN Document Server

    Mehmandoost-Khajeh-Dad, A A; Amir-Ahmadi, H R; Bacelar, J C S; Berg, A M van den; Castelijns, R; van Garderen, E D; Kalantar-Nayestanaki, N; Kiš, M; Löhner, H; Messchendorp, J G; Wörtche, H J

    2011-01-01

    Differential cross sections of the reaction $p(d,^3{\\rm He})\\gamma$ have been measured at deuteron laboratory energies of 110, 133 and 180 MeV. The data were obtained with a coincidence setup measuring both the outgoing $^3$He and the photon. The data are compared with modern calculations including all possible meson-exchange currents and two- and three- nucleon forces in the potential. The data clearly show a preference for one of the models, although the shape of the angular distribution cannot be reproduced by any of the presented models.

  10. Low-energy fission investigated in reactions of 750 AMeV {sup 238}U-ions with Pb and Be targets. Pt. 1. Nuclear charge distributions

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, P. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Bernas, M. [IPN Orsay, 91 Orsay (France); Czajkowski, S. [IPN Orsay, 91 Orsay (France); Geissel, H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Aumann, T. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Dessagne, P. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Donzaud, C. [IPN Orsay, 91 Orsay (France); Hanelt, E. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Heinz, A. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Hesse, M. [Tuebingen Univ. (Germany). Physikalisches Inst.; Kozhuharov, C. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Miehe, C. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Muenzenberg, G. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Pfuetzner, M. [Warsaw Univ. (Poland); Schmidt, K.H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Schwab, W. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Stephan, C. [IPN Orsay, 91 Orsay (France); Suemmerer, K. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Tassan-got, L. [IPN Orsay, 91 Orsay (France); Voss, B. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik

    1996-07-01

    Charge distributions of fragments from low energy nuclear fission are investigated in reactions of highly fissile {sup 238}U projectiles at relativistic energies (750 A.MeV) with a heavy (Pb) and a light (Be) target. The fully stripped fission fragments are separated by the fragment separator (FRS). Their high kinetic energies in the laboratory system allow the identification of all atomic numbers by using multiple-sampling ionization chambers (MUSIC). The elemental distributions of fragments observed at larger magnetic rigidities than the {sup 238}U projectiles show asymmetric break-up and odd-even effects. They indicate a low energy fission process, induced mainly by dissociation in the electro-magnetic field for the U/Pb-system, or by peripheral nuclear interactions for the U/Be-system. (orig.)

  11. Low energy fission investigated in reactions of 750 AMeV {sup 238}U-ions with Pb and Be targets

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, P. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Bernas, M. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Czajkowski, S. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Geissel, H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Aumann, T. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Dessagne, P. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Donzaud, C. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Hanelt, E. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Heinz, A. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Hesse, M. [Tuebingen Univ. (Germany). Physikalisches Inst.; Kozhuharov, C. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Miehe, C. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Muenzenberg, G. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Pfuetzner, M. [Warsaw Univ. (Poland); Schmidt, K.H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Schwab, W. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Stephan, C. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Suemmerer, K. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Tassan-Got, L. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Voss, B. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik

    1995-10-01

    Charge distributions of fragments from low energy nuclear fission are investigated in reactions of highly fissile {sup 238}U projectiles at relativistic energies (750 AMeV) with a heavy (Pb) and a light (Be) target. The fully stripped fission fragments are separated by the Fragment Separator (FRS). Their high kinetic energies in the laboratory system allow the identification of all atomic numbers by using Multiple-Sample Ionization Chambers (MUSIC). The elemental distributions of fragments observed at larger magnetic rigidities than the {sup 238}U projectiles show asymmetric break-up and odd-even effects. They indicate a low energy fission process, induced mainly by dissociation in the electromagnetic field for the U/Pb-system, or by peripheral nuclear interactions for the U/Be-system. (orig.)

  12. Low-energy fission investigated in reactions of 750 AMeV238U-ions with Pb and Be targets. I. Nuclear charge distributions

    Science.gov (United States)

    Armbruster, P.; Bernas, M.; Czajkowski, S.; Geissel, H.; Aumann, T.; Dessagne, Ph.; Donzaud, C.; Hanelt, E.; Heinz, A.; Hesse, M.; Kozhuharov, C.; Miehe, Ch.; Münzenberg, G.; Pfützner, M.; Schmidt, K.-H.; Schwab, W.; Stéphan, C.; Sümmerer, K.; Tassan-Got, L.; Voss, B.

    1996-12-01

    Charge distributions of fragments from low energy nuclear fission are investigated in reactions of highly fissile238U projectiles at relativistic energies (750 A·MeV) with a heavy (Pb) and a light (Be) target. The fully stripped fission fragments are separated by the Fragment Separator (FRS). Their high kinetic energies in the laboratory system allow the identification of all atomic numbers by using Multiple-Sampling Ionization Chambers (MUSIC). The elemental distributions of fragments observed at larger magnetic rigidities than the238U projectiles show asymmetric break-up and odd-even effects. They indicate a low energy fission process, induced mainly by dissociation in the electro-magnetic field for the U/Pb-system, or by peripheral nuclear interactions for the U/Be-system.

  13. Plunger lifetime measurements after Coulomb excitation at intermediate beam energies

    Energy Technology Data Exchange (ETDEWEB)

    Hackstein, Matthias; Dewald, Alfred; Fransen, Christoph; Ilie, Gabriela; Jolie, Jan; Melon, Barbara; Pissulla, Thomas; Rother, Wolfram; Zell, Karl-Oskar [University of Cologne (Germany); Petkov, Pavel [University of Cologne (Germany); INRNE (Bulgaria); Chester, Aaron; Adrich, Przemyslaw; Bazin, Daniel; Bowen, Matt; Gade, Alexandra; Glasmacher, Thomas; Miller, Dave; Moeller, Victoria; Starosta, Krzysztof; Stolz, Andreas; Vaman, Constantin; Voss, Philip; Weissharr, Dirk [Michigan State Univerity (United States); Moeller, Oliver [TU Darmstadt (Germany)

    2008-07-01

    Two recoil-distance-doppler-shift (RDDS) experiments were performed at the NSCL/MSU using Coulomb excitations of the projectile nuclei {sup 110}Pd, {sup 114}Pd at beam energies of 54 MeV/u in order to investigate the evolution of deformation of neutron rich paladium isotopes. The experimental set-up consisted of a dedicated plunger device, developed at the University of Cologne, the SEGA Ge-array and the S800 spectrometer. Lifetimes of the 2{sub 1}{sup +}-states in {sup 110}Pd and {sup 114}Pd were derived from the analysis of the {gamma}-line-shapes as well as from the measured decay-curves. Special features of the data analysis, e.g. features originating from the very high recoil velocities, are discussed.

  14. New stopping power formula for intermediate energy electrons.

    Science.gov (United States)

    Gümüş, Hasan

    2008-12-01

    This study presents a new stopping power (SP) formula for electrons. In the modified Bethe-Bloch SP expression, analytical expressions for the effective charge and effective mean excitation energies (EMEE) of target atoms are used, while for the effective charge of incoming electrons, Sugiyama's semiempirical formula from Peterson and Green is used. An analytical expression for practical SP calculations is obtained using the Bethe approximation and a Thomas-Fermi model of the atom. The calculated results of the SP for electrons in some materials, such as H(2)O, H(2), CO(2), N(2), and O(2), are compared with experimental data, together with Penelope code results and a number of other semiempirical and analytical calculations.

  15. HYPERFUSE: a hypervelocity inertial confinement system for fusion energy production and fission waste transmutation

    Energy Technology Data Exchange (ETDEWEB)

    Makowitz, H.; Powell, J.R.; Wiswall, R.

    1980-01-01

    Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from a LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., /sup 137/Cs, /sup 90/Sr, /sup 129/I, /sup 99/Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,..cap alpha..), (n,..gamma..), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R = 1.0 to 3.0) requirements. These studies also indicate that masses on the order of 1.0 g at densities of rho greater than or equal to 500.0 g/cm/sup 3/ are required for a practical fusion-based fission product transmutation system.

  16. UCLA Intermediate Energy Nuclear and Particle Physics Research: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Nefkens, B M.K. [Principal Investigator, ed.; Goetz, J; Lapik, A; Korolija, M; Prakhov, S; Starostin, A [ed.

    2011-05-18

    This project covers the following research: (a) Investigations into the structure of the proton and neutron. This is done by investigating the different resonance states of nucleons with beams of tagged, polarized photons, linearly as well as circularly, incident on polarized hydrogen/deuterium targets and measuring the production of {pi}{sup 0}, 2{pi}{sup }0, 3{pi}{sup 0}, {eta} , {eta}', {omega}, etc. The principal detector is the Crystal Ball multiphoton spectrometer which has an acceptance of nearly 4 . It has been moved to the MAMI accelerator facility of the University of Mainz, Germany. We investigate the conversion of electromagnetic energy into mesonic matter and conversely. (b) We investigate the consequences of applying the "standard" symmetries of isospin, G-parity, charge conjugation, C, P, T, and chirality using rare and forbidden decays of light mesons such as the {eta} ,{eta}' and {omega}. We also investigate the consequences of these symmetries being slightly broken symmetries. We do this by studying selected meson decays using the Crystal Ball detector. (c) We determine the mass, or more precisely the mass difference of the three light quarks (which are inputs to Quantum Chromodynamics) by measuring the decay rate of specially selected {eta} and {eta}' decay modes, again we use the Crystal Ball. (d)We have started a new program to search for the 33 missing cascade baryons using the CLAS detector at the Thomas Jefferson Laboratory. Cascade resonances are very special: they have double strangeness and are quite narrow. This implies that they can be discovered by the missing mass technique in photoproduction reactions such as in {gamma}p{yields}{Xi}{sup}K{sup +}K{sup +}. The cascade program is of particular importance for the upgrade to 12 GeV of the CLAS detector and for design of the Hall D at JLab. (e) Finally, we are getting more involved in a new program to measure the hadronic matter form factor of complex nuclei, in particular

  17. Pion- and proton-nucleus interactions at intermediate energy

    Energy Technology Data Exchange (ETDEWEB)

    Dehnhard, D.

    1992-02-01

    {pi}-meson and proton beams from the Los Alamos Meson Physics Facility (LAMPF) and the Indiana University Cyclotron Facility (IUCF) were used in scattering and reaction experiments on atomic nuclei. The experimental data allow tests of models of the reaction mechanism and of nuclear structure. For example, the asymmetries observed in a pion scattering experiment on polarized {sup 13}C nuclei were found to contain unique information on the isoscalar spin density. However, further experiments on polarized nuclei of simpler structure are needed to provide the data for a thorough analysis of the reaction mechanism. For this reason a pion scattering experiment on a polarized {sup 3}He target is planned and a high-resolution study on {sup 6}Li({pi},{pi}{prime}) will be done. An analysis of {pi}-triton coincidence events from the {sup 4}He({pi},{pi}{prime}t)p reaction yielded evidence for direct triton knock-out from {sup 4}He. This work will be continued at higher incident pion energies. Additional work on the {sup 4}He(p,n) reaction at IUCF is planned to determine the isovector strength in mass-4 nuclei and the level parameters of {sup 4}Li.

  18. Calculation of depth-dose distribution of intermediate energy heavy-ion beams

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the characteristics of the interactions between intermediate energy heavy-ion beam and target matter, a method to calculate the depth-dose distribution of heavy-ion beams with intermediate energy (10 -100 MeV/u) is presented. By comparing high energy beams where projectile fragmentation is overwhelm ing with lowenergies where energy straggling is the sole factor instead, a crescent energy spread with increasing depth and a simple fragmentation assumption were included for the depth-dose calculation of the intermediate energy beam. Rel ative depth-dose curves of carbon and oxygen ion beams with intermediate energie s were computed according to the method here. Comparisons between the calculated relative doses and measurements are shown. The calculated Bragg curves, especially the upstream and downstream Bragg peaks, agree with the measured data. Differences between the two results appear only around the peak regions because of th e limitations of the calculation and experimental conditions, but the calculated curves generally reproduce the measured data within the experimental errors. Th e reasons for the divergences were analyzed carefully and the magnitudes of the deviations are given.

  19. Neutron-rich rare isotope production from projectile fission of heavy beams in the energy range of 20 MeV/nucleon

    CERN Document Server

    Vonta, N; Loveland, W D; Kwon, Y K; Tshoo, K; Jeong, S C; Veselsky, M; Bonasera, A; Botvina, A

    2016-01-01

    We investigate the possibilities of producing neutron-rich nuclides in projectile fission of heavy beams in the energy range of 20 MeV/nucleon expected from low-energy facilities. We report our efforts to theoretically describe the reaction mechanism of projectile fission following a multinucleon transfer collision at this energy range. Our calculations are mainly based on a two-step approach: the dynamical stage of the collision is described with either the phenomenological Deep-Inelastic Transfer model (DIT), or with the microscopic Constrained Molecular Dynamics model (CoMD). The deexcitation/fission of the hot heavy projectile fragments is performed with the Statistical Mul- tifragmentation Model (SMM). We compared our model calculations with our previous experimental projectile-fission data of 238U (20 MeV/nucleon)+208Pb and 197Au (20 MeV/nucleon)+197Au and found an overall reasonable agreement. Our study suggests that projectile fission following periph- eral heavy-ion collisions at this energy range of...

  20. Neutron-rich rare-isotope production from projectile fission of heavy nuclei near 20 MeV/nucleon beam energy

    Science.gov (United States)

    Vonta, N.; Souliotis, G. A.; Loveland, W.; Kwon, Y. K.; Tshoo, K.; Jeong, S. C.; Veselsky, M.; Bonasera, A.; Botvina, A.

    2016-12-01

    We investigate the possibilities of producing neutron-rich nuclides in projectile fission of heavy beams in the energy range of 20 MeV/nucleon expected from low-energy facilities. We report our efforts to theoretically describe the reaction mechanism of projectile fission following a multinucleon transfer collision at this energy range. Our calculations are mainly based on a two-step approach: The dynamical stage of the collision is described with either the phenomenological deep-inelastic transfer model (DIT) or with the microscopic constrained molecular dynamics model (CoMD). The de-excitation or fission of the hot heavy projectile fragments is performed with the statistical multifragmentation model (SMM). We compared our model calculations with our previous experimental projectile-fission data of 238U (20 MeV/nucleon) + 208Pb and 197Au (20 MeV/nucleon) + 197Au and found an overall reasonable agreement. Our study suggests that projectile fission following peripheral heavy-ion collisions at this energy range offers an effective route to access very neutron-rich rare isotopes toward and beyond the astrophysical r-process path.

  1. Standard test method for gamma energy emission from fission products in uranium hexafluoride and uranyl nitrate solution

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This test method covers the measurement of gamma energy emitted from fission products in uranium hexafluoride (UF6) and uranyl nitrate solution. It is intended to provide a method for demonstrating compliance with UF6 specifications C 787 and C 996 and uranyl nitrate specification C 788. 1.2 The lower limit of detection is 5000 MeV Bq/kg (MeV/kg per second) of uranium and is the square root of the sum of the squares of the individual reporting limits of the nuclides to be measured. The limit of detection was determined on a pure, aged natural uranium (ANU) solution. The value is dependent upon detector efficiency and background. 1.3 The nuclides to be measured are106Ru/ 106Rh, 103Ru,137Cs, 144Ce, 144Pr, 141Ce, 95Zr, 95Nb, and 125Sb. Other gamma energy-emitting fission nuclides present in the spectrum at detectable levels should be identified and quantified as required by the data quality objectives. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its us...

  2. Dynamical features of nuclear fission

    Indian Academy of Sciences (India)

    Santanu Pal

    2015-08-01

    It is now established that the transition-state theory of nuclear fission due to Bohr and Wheeler underestimates several observables in heavy-ion-induced fusion–fission reactions. Dissipative dynamical models employing either the Langevin equation or equivalently the Fokker–Planck equation have been developed for fission of heavy nuclei at high excitations (T ∼1 MeV or higher). Here, we first present the physical picture underlying the dissipative fission dynamics. We mainly concentrate upon the Kramers’ prescription for including dissipation in fission dynamics. We discuss, in some detail, the results of a statistical model analysis of the pre-scission neutron multiplicity data from the reactions 19F+194,196,198Pt using Kramers’ fission width. We also discuss the multi-dimensional Langevin equation in the context of kinetic energy and mass distribution of the fission fragments.

  3. Fission modes of mercury isotopes

    CERN Document Server

    Warda, M; Nazarewicz, W

    2012-01-01

    Recent experiments on beta-delayed fission in the mercury-lead region and the discovery of asymmetric fission in $^{180}$Hg [1] have stimulated renewed interest in the mechanism of fission in heavy nuclei. Here we study fission modes and fusion valleys in $^{180}$Hg and $^{198}$Hg using the self-consistent nuclear density functional theory employing Skyrme and Gogny energy density functionals. We show that the observed transition from asymmetric fission in $^{180}$Hg towards more symmetric distribution of fission fragments in $^{198}$Hg can be explained in terms of competing fission modes of different geometries that are governed by shell effects in pre-scission configurations. The density distributions at scission configurations are studied and related to the experimentally observed mass splits.

  4. Point-by-point model calculation of the prompt neutron multiplicity distribution ν(A) in the incident neutron energy range of multi-chance fission

    Science.gov (United States)

    Tudora, Anabella; Hambsch, Franz-Josef; Tobosaru, Viorel

    2017-09-01

    Prompt neutron multiplicity distributions ν(A) are required for prompt emission correction of double energy (2E) measurements of fission fragments to determine pre-neutron fragment properties. The lack of experimental ν(A) data especially at incident neutron energies (En) where the multi-chance fission occurs impose the use of ν(A) predicted by models. The Point-by-Point model of prompt emission is able to provide the individual ν(A) of the compound nuclei of the main and secondary nucleus chains undergoing fission at a given En. The total ν(A) is obtained by averaging these individual ν(A) over the probabilities of fission chances (expressed as total and partial fission cross-section ratios). An indirect validation of the total ν(A) results is proposed. At high En, above 70 MeV, the PbP results of individual ν(A) of the first few nuclei of the main and secondary nucleus chains exhibit an almost linear increase. This shape is explained by the damping of shell effects entering the super-fluid expression of the level density parameters. They tend to approach the asymptotic values for most of the fragments. This fact leads to a smooth and almost linear increase of fragment excitation energy with the mass number that is reflected in a smooth and almost linear behaviour of ν(A).

  5. The Complete Burning of Weapons Grade Plutonium and Highly Enriched Uranium with (Laser Inertial Fusion-Fission Energy) LIFE Engine

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Diaz de la Rubia, T; Moses, E

    2008-12-23

    The National Ignition Facility (NIF) project, a laser-based Inertial Confinement Fusion (ICF) experiment designed to achieve thermonuclear fusion ignition and burn in the laboratory, is under construction at the Lawrence Livermore National Laboratory (LLNL) and will be completed in April of 2009. Experiments designed to accomplish the NIF's goal will commence in late FY2010 utilizing laser energies of 1 to 1.3 MJ. Fusion yields of the order of 10 to 20 MJ are expected soon thereafter. Laser initiated fusion-fission (LIFE) engines have now been designed to produce nuclear power from natural or depleted uranium without isotopic enrichment, and from spent nuclear fuel from light water reactors without chemical separation into weapons-attractive actinide streams. A point-source of high-energy neutrons produced by laser-generated, thermonuclear fusion within a target is used to achieve ultra-deep burn-up of the fertile or fissile fuel in a sub-critical fission blanket. Fertile fuels including depleted uranium (DU), natural uranium (NatU), spent nuclear fuel (SNF), and thorium (Th) can be used. Fissile fuels such as low-enrichment uranium (LEU), excess weapons plutonium (WG-Pu), and excess highly-enriched uranium (HEU) may be used as well. Based upon preliminary analyses, it is believed that LIFE could help meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the nation's and world's stockpile of spent nuclear fuel and excess weapons materials. LIFE takes advantage of the significant advances in laser-based inertial confinement fusion that are taking place at the NIF at LLNL where it is expected that thermonuclear ignition will be achieved in the 2010-2011 timeframe. Starting from as little as 300 to 500 MW of fusion power, a single LIFE engine will be able to generate 2000 to 3000 MWt in steady state for periods of years to decades, depending on the nuclear fuel and engine configuration. Because the fission

  6. Neutron Transport and Nuclear Burnup Analysis for the Laser Inertial Confinement Fusion-Fission Energy (LIFE) Engine

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, K J; Latkowski, J F; Abbott, R P; Boyd, J K; Powers, J J; Seifried, J E

    2008-10-24

    Lawrence Livermore National Laboratory is currently developing a hybrid fusion-fission nuclear energy system, called LIFE, to generate power and burn nuclear waste. We utilize inertial confinement fusion to drive a subcritical fission blanket surrounding the fusion chamber. It is composed of TRISO-based fuel cooled by the molten salt flibe. Low-yield (37.5 MJ) targets and a repetition rate of 13.3 Hz produce a 500 MW fusion source that is coupled to the subcritical blanket, which provides an additional gain of 4-8, depending on the fuel. In the present work, we describe the neutron transport and nuclear burnup analysis. We utilize standard analysis tools including, the Monte Carlo N-Particle (MCNP) transport code, ORIGEN2 and Monteburns to perform the nuclear design. These analyses focus primarily on a fuel composed of depleted uranium not requiring chemical reprocessing or enrichment. However, other fuels such as weapons grade plutonium and highly-enriched uranium are also under consideration. In addition, we have developed a methodology using {sup 6}Li as a burnable poison to replace the tritium burned in the fusion targets and to maintain constant power over the lifetime of the engine. The results from depleted uranium analyses suggest up to 99% burnup of actinides is attainable while maintaining full power at 2GW for more than five decades.

  7. Low-lying Regge trajectory and polarizations in. pi. /sup +/P elastic reaction at intermediate energy

    Energy Technology Data Exchange (ETDEWEB)

    Girardi, G.; Navelet, H.

    1976-07-01

    In this note we examine how a low-lying Regge trajectory provides a natural explanation of the departure from mirror symmetry in the ..pi..N elastic-scattering polarization at intermediate energy. This result confirms the conjecture of Dash and Navelet, who invoke the same mechanism in NN scattering. (AIP)

  8. Flow and multifragmentation of $^{24}$Mg + $^{27}$Al at intermediate energies

    NARCIS (Netherlands)

    Prendergast, E. P.; Brink, A. van der; Haas, A. P. de; Kamermans, R.; Kuijer, P. G.; Laat, C. T. A. M. de; Ostendorf, R. W.; Oti, E.; Péghaire, A.; Snellings, R. J. M.

    1999-01-01

    Submitted to: Phys. Rev. C Abstract: An elaborated investigation was done into the reaction mechanism of heavy ion collisions at intermediate energies of small nuclear systems. Experimental data measured with the Huygens detectors and IQMD simulations of mgal at 45 and 95 amev were analysed with res

  9. Hidden systematics of fission channels

    Directory of Open Access Journals (Sweden)

    Schmidt Karl-Heinz

    2013-12-01

    Full Text Available It is a common procedure to describe the fission-fragment mass distributions of fissioning systems in the actinide region by a sum of at least 5 Gaussian curves, one for the symmetric component and a few additional ones, together with their complementary parts, for the asymmetric components. These components have been attributed to the influence of fragment shells, e.g. in the statistical scission-point model of Wilkins, Steinberg and Chasman. They have also been associated with valleys in the potential-energy landscape between the outer saddle and the scission configuration in the multi-channel fission model of Brosa. When the relative yields, the widths and the mean mass-asymmetry values of these components are fitted to experimental data, the mass distributions can be very well reproduced. Moreover, these fission channels are characterised by specific values of charge polarisation, total kinetic energy and prompt-neutron yields. The present contribution investigates the systematic variation of the characteristic fission-channel properties as a function of the composition and the excitation energy of the fissioning system. The mean position of the asymmetric fission channels in the heavy fragment is almost constant in atomic number. The deformation of the nascent fragments at scission, which is the main source of excitation energy of the separated fission fragments ending up in prompt-neutron emission, is found to be a unique function of Z for the light and the heavy fragment of the asymmetric fission channels. A variation of the initial excitation energy of the fissioning system above the fission saddle is only seen in the neutron yield of the heavy fragment. The charge polarisation in the two most important asymmetric fission channels is found to be constant and to appreciably exceed the macroscopic value. The variation of the relative yields and of the positions of the fission channels as a function of the composition and excitation energy

  10. Experimental Neutron-Induced Fission Fragment Mass Yields of 232Th and 238U at Energies from 10 to 33 MeV

    CERN Document Server

    Simutkin, V D; Blomgren, J; Österlund, M; Bevilacqua, R; Ryzhov, I V; Tutin, G A; Yavshits, S G; Vaishnene, L A; Onegin, M S; Meulders, J P; Prieels, R

    2013-01-01

    Development of nuclear energy applications requires data for neutron-induced reactions for actinides in a wide neutron energy range. Here we describe measurements of pre-neutron emission fission fragment mass yields of 232Th and 238U at incident neutron energies from 10 to 33 MeV. The measurements were done at the quasi-monoenergetic neutron beam of the Louvain-la-Neuve cyclotron facility CYCLONE; a multi-section twin Frisch-gridded ionization chamber was used to detect fission fragments. For the peak neutron energies at 33, 45 and 60 MeV, the details of the data analysis and the experimental results have been published before and in this work we present data analysis in the low-energy tail of the neutron energy spectra. The preliminary measurement results are compared with available experimental data and theoretical predictions.

  11. Structural effects in UO2 thin films irradiated with fission-energy Xe ions

    Science.gov (United States)

    Popel, A. J.; Lebedev, V. A.; Martin, P. G.; Shiryaev, A. A.; Lampronti, G. I.; Springell, R.; Kalmykov, S. N.; Scott, T. B.; Monnet, I.; Grygiel, C.; Farnan, I.

    2016-12-01

    Uranium dioxide thin films have been successfully grown on LSAT (Al10La3O51Sr14Ta7) substrates by reactive magnetron sputtering. Irradiation by 92 MeV 129Xe23+ ions to simulate fission damage that occurs within nuclear fuels caused microstructural and crystallographic changes. Initially flat and continuous thin films were produced by magnetron sputtering with a root mean square roughness of 0.35 nm determined by AFM. After irradiation, this roughness increased to 60-70 nm, with the films developing discrete microstructural features: small grains (∼3 μm), along with larger circular (up to 40 μm) and linear formations with non-uniform composition according to the SEM, AFM and EDX results. The irradiation caused significant restructuring of the UO2 films that was manifested in significant film-substrate mixing, observed through EDX analysis. Diffusion of Al from the substrate into the film in unirradiated samples was also observed.

  12. Intermediate Mass Fragment Emission Pattern in Peripheral Heavy-Ion Collisions at Fermi Energies

    Science.gov (United States)

    Piantelli, S.; Bidini, L.; Poggi, G.; Bini, M.; Casini, G.; Maurenzig, P. R.; Olmi, A.; Pasquali, G.; Stefanini, A. A.; Taccetti, N.

    2002-02-01

    The emission pattern in the vperp-vpar plane of intermediate mass fragments with Z = 3-7 (IMF) has been studied in the collision 116Sn+ 93Nb at 29.5A MeV as a function of the total kinetic energy loss of the reaction. This pattern shows that for peripheral reactions most IMF's are emitted at velocities intermediate between those of the projectile- and target-like products. Coulomb trajectory calculations show that these IMF's are produced in the interaction zone in a short time interval at the end of the target-projectile interaction.

  13. An analytic solution for energy loss and time-of-flight calculations for intermediate-energy light ions

    NARCIS (Netherlands)

    Snellings, RJM; Hulsbergen, W; Prendergast, EP; van den Brink, A; de Haas, AP; Habets, JJLM; Kamermans, R; Koopmans, M; Kuijer, PG; de Laat, CTAM; Ostendorf, RW; Peghaire, A; Rossewij, M

    1999-01-01

    Particle identification in intermediate heavy-ion collisions, using a modern 4 pi detector which contains several active layers, relies on a parametrisation or numerical integration of the energy loss in thick layers of detector material for different ions. Here an analytical solution applicable ove

  14. Decay modes in spontaneous fission

    CERN Document Server

    Gönnenwein, F

    1999-01-01

    Spontaneous fission (SF) is considered to be the choice reaction for studying the influence of shell and pairing effects in fission in general, and in particular their impact on the mass and energy distributions of fission fragments. For the time being some 35 SF reactions have been analysed in detail for elements ranging from Pu up to Rf. Going from the lighter to the heavier actinides both, the distributions of fragment mass (or charge) and of total kinetic energy undergo dramatic changes. It is observed in experiment, however, that these distributions may be well described as a superposition of a few fission modes, each with its own characteristic mass an energy pattern. The experimental modes are traced in theory to fine structures in the potential energy surface of a fissioning nucleus, provided shell and pairing corrections to the basic liquid drop model are accounted for.

  15. GGA+U study of uranium mononitride: A comparison of the U-ramping and occupation matrix schemes and incorporation energies of fission products

    Energy Technology Data Exchange (ETDEWEB)

    Claisse, Antoine, E-mail: claisse@kth.se [KTH Royal Institute of Technology, Reactor Physics, AlbaNova University Centre, 106 91 Stockholm (Sweden); Klipfel, Marco [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); Lindbom, Niclas [KTH Royal Institute of Technology, Reactor Physics, AlbaNova University Centre, 106 91 Stockholm (Sweden); Freyss, Michel [CEA, DEN, DEC, Centre de Cadarache, 13108 Saint-Paul-lez-Durance (France); Olsson, Pär [KTH Royal Institute of Technology, Reactor Physics, AlbaNova University Centre, 106 91 Stockholm (Sweden)

    2016-09-15

    Uranium mononitride is studied in the DFT + U framework. Its ground state is investigated and a study of the incorporation of diverse fission products in the crystal is conducted. The U-ramping and occupation matrix control (OMC) schemes are used to eliminate metastable states. Beyond a certain amount of introduced correlation, the OMC scheme starts to find a lower total energy. The OMC scheme is chosen for the second part of this study. Furthermore, the influence of the magnetic ordering is studied using the U-ramping method, showing that antiferromagnetic order is the most stable one when the U parameter is larger than 1.75 eV. The effect on the density of states is investigated and elastic constants are provided for comparison with other methods and experiments. The incorporation energies of fission products in different defect configurations are calculated and these energies are corrected to take into account the limited size of the supercell. - Highlights: • We studied bulk uranium nitride with means of DFT+U with the U-ramping scheme and the OMC scheme. • We produces a density of states plot and calculated the elastic constants of UN. • We calculated the incorporation energy of many fission products in UN, and corrected them to take into account the elastic interactions. • The OMC scheme should be used over the U-ramping scheme. • Fission products go to larger crystal sites.

  16. Experimental approach to fission process of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Hiroshi [Osaka Univ., Toyonaka (Japan). Faculty of Science

    1997-07-01

    From experimental views, it seems likely that the mechanism of nuclear fission process remains unsolved even after the Bohr and Weeler`s study in 1939. Especially, it is marked in respect of mass distribution in unsymmetric nuclear fission. The energy dependency of mass distribution can be explained with an assumption of 2-mode nuclear fission. Further, it was demonstrated that the symmetrical fission components and the unsymmetrical ones have different saddle and fission points. Thus, the presence of the 2-mode fission mechanism was confirmed. Here, transition in the nuclear fission mechanism and its cause were investigated here. As the cause of such transition, plausible four causes; a contribution of multiple-chance fission, disappearance of shell effects, beginning of fission following collective excitation due to GDR and nuclear phase transition were examined in the condition of excitation energy of 14.0 MeV. And it was suggested that the transition in the nuclear fission concerned might be related to phase transition. In addition, the mechanism of nuclear fission at a low energy and multi-mode hypothesis were examined by determination of the energy for thermal neutron fission ({sup 233,235}U and {sup 239}Pu) and spontaneous nuclear fission ({sup 252}Cf). (M.N.)

  17. MCNP6 Simulation of Light and Medium Nuclei Fragmentation at Intermediate Energies

    Energy Technology Data Exchange (ETDEWEB)

    Mashnik, Stepan Georgievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kerby, Leslie Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Idaho, Moscow, ID (United States)

    2015-08-24

    Fragmentation reactions induced on light and medium nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the Los Alamos transport code MCNP6 and with its CEM03.03 and LAQGSM03.03 event generators. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to sup>4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

  18. MCNP6 simulation of light and medium nuclei fragmentation at intermediate energies

    Directory of Open Access Journals (Sweden)

    Mashnik Stepan G.

    2016-01-01

    Full Text Available Fragmentation reactions induced on light and medium nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the Los Alamos transport code MCNP6 and with its CEM03.03 and LAQGSM03.03 event generators. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC, followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. CEM and LAQGSM account also for coalescence of light fragments (complex particles up to 4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

  19. MCNP6 simulation of light and medium nuclei fragmentation at intermediate energies

    CERN Document Server

    Mashnik, Stepan G

    2015-01-01

    Fragmentation reactions induced on light and medium nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the Los Alamos transport code MCNP6 and with its CEM03.03 and LAQGSM03.03 event generators. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to 4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes

  20. MCNP6 simulation of light and medium nuclei fragmentation at intermediate energies

    Science.gov (United States)

    Mashnik, Stepan G.; Kerby, Leslie M.

    2016-05-01

    Fragmentation reactions induced on light and medium nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the Los Alamos transport code MCNP6 and with its CEM03.03 and LAQGSM03.03 event generators. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to 4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

  1. Neutron emission effects on fragment mass and kinetic energy distribution from fission of 239Pu induced by thermal neutrons

    Science.gov (United States)

    Montoya, M.; Rojas, J.; Lobato, I.

    2010-08-01

    The average of fragment kinetic energy (E*) and the multiplicity of prompt neutrons (ν) as a function of fragment mass (m*), as well as the fragment mass yield (Y(m*)) from thermal neutron-induced fission of 239Pu have been measured by Tsuchiya et al.. In that work the mass and kinetic energy are calculated from the measured kinetic energy of one fragment and the difference of time of flight of the two complementary fragments. However they do not present their results about the standard deviation σE*(m*). In this work we have made a numerical simulation of that experiment which reproduces its results, assuming an initial distribution of the primary fragment kinetic energy (E(A)) with a constant value of the standard deviation as function of fragment mass (σE(A)). As a result of the simulation we obtain the dependence σE*(m*) which presents an enhancement between m* = 92 and m* = 110, and a peak at m* = 121.

  2. Differential cross sections for electron-impact vibrational-excitation of tetrahydrofuran at intermediate impact energies

    Energy Technology Data Exchange (ETDEWEB)

    Do, T. P. T. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); School of Education, Can Tho University, Campus II, 3/2 Street, Xuan Khanh, Ninh Kieu, Can Tho City (Viet Nam); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Konovalov, D. A.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville (Australia); Brunger, M. J., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jones, D. B., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

    2015-03-28

    We report differential cross sections (DCSs) for electron-impact vibrational-excitation of tetrahydrofuran, at intermediate incident electron energies (15-50 eV) and over the 10°-90° scattered electron angular range. These measurements extend the available DCS data for vibrational excitation for this species, which have previously been obtained at lower incident electron energies (≤20 eV). Where possible, our data are compared to the earlier measurements in the overlapping energy ranges. Here, quite good agreement was generally observed where the measurements overlapped.

  3. Axisymmetric Magnetic Mirror Fusion-Fission Hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Moir, R. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martovetsky, N. N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Molvik, A. W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simonen, T. C. [Univ. of California, Berkeley, CA (United States)

    2011-05-13

    The achieved performance of the gas dynamic trap version of magnetic mirrors and today’s technology we believe are sufficient with modest further efforts for a neutron source for material testing (Q=Pfusion/Pinput~0.1). The performance needed for commercial power production requires considerable further advances to achieve the necessary high Q>>10. An early application of the mirror, requiring intermediate performance and intermediate values of Q~1 are the hybrid applications. The Axisymmetric Mirror has a number of attractive features as a driver for a fusion-fission hybrid system: geometrical simplicity, inherently steady-state operation, and the presence of the natural divertors in the form of end tanks. This level of physics performance has the virtue of low risk and only modest R&D needed and its simplicity promises economy advantages. Operation at Q~1 allows for relatively low electron temperatures, in the range of 4 keV, for the DT injection energy ~ 80 keV. A simple mirror with the plasma diameter of 1 m and mirror-to-mirror length of 35 m is discussed. Simple circular superconducting coils are based on today’s technology. The positive ion neutral beams are similar to existing units but designed for steady state. A brief qualitative discussion of three groups of physics issues is presented: axial heat loss, MHD stability in the axisymmetric geometry, microstability of sloshing ions. Burning fission reactor wastes by fissioning actinides (transuranics: Pu, Np, Am, Cm, .. or just minor actinides: Np, Am, Cm, …) in the hybrid will multiply fusion’s energy by a factor of ~10 or more and diminish the Q needed to less than 1 to overcome the cost of recirculating power for good economics. The economic value of destroying actinides by fissioning is rather low based on either the cost of long-term storage or even deep geologic disposal so most of the revenues of hybrids will come from electrical power. Hybrids that obtain revenues from

  4. Isoscaling of the Fission Fragments with Langevin Equation

    Institute of Scientific and Technical Information of China (English)

    WANG Kun; TIAN Wen-Dong; ZHONG Chen; ZHOU Xing-Fei; MA Yu-Gang; WEI Yi-Bin; CAI Xiang-Zhou; CHEN Jin-Gen; FANG De-Qing; GUO Wei; MA Guo-Liang; SHEN Wen-Qing

    2005-01-01

    @@ The Langevin equation is used to simulate the fission process of 112Sn + 112Sn and 116Sn + 116Sn. The mass distribution of the fission fragments are given by assuming the process of symmetric fission or asymmetric fission with the Gaussian probability sampling. The isoscaling behaviour has been observed from the analysis of fission fragments of both the reactions, and the isoscaling parameter α seems to be sensitive to the width of fission probability and the beam energy.

  5. Benchmarking of activation reaction distribution in an intermediate energy neutron field.

    Science.gov (United States)

    Ogawa, Tatsuhiko; Morev, Mikhail N; Hirota, Masahiro; Abe, Takuya; Koike, Yuya; Iwai, Satoshi; Iimoto, Takeshi; Kosako, Toshiso

    2011-07-01

    Neutron-induced reaction rate depth profiles inside concrete shield irradiated by intermediate energy neutron were calculated using a Monte-Carlo code and compared with an experiment. An irradiation field of intermediate neutron produced in the forward direction from a thick (stopping length) target bombarded by 400 MeV nucleon(-1) carbon ions was arranged at the heavy ion medical accelerator in Chiba. Ordinary concrete shield of 90 cm thickness was installed 50 cm downstream the iron target. Activation detectors of aluminum, gold and gold covered with cadmium were inserted at various depths. Irradiated samples were extracted after exposure and gamma-ray spectrometry was performed for each sample. Comparison of experimental and calculated shows good agreement for both low- and high-energy neutron-induced reaction except for (27)Al(n,X)(24)Na reaction at the surface.

  6. Thermal-neutron-induced alpha-accompanied fission of /sup 235/U investigation of the low energy part of the alpha spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Caitucoli, F. (CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France). Dept. de Recherche Fondamentale); Leroux, B.; Cajan, N.; Benfoughal, T.; Doan, T.P.; El Hage, F.; Sicre, A. (CEA Centre d' Etudes Nucleaires de Bordeaux-Gradignan, 33 - Gradignan (France)); Asghar, M. (Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)); Barreau, G.; Perrin, P. (Institut Max von Laue - Paul Langevin, 38 - Grenoble (France))

    1980-01-01

    The energy spectrum of the ..cap alpha..-particles emitted in the thermal-neutron induced fission of /sup 235/U was measured from 11.5 MeV down to 2 MeV using the parabola mass spectrometer Lohengrin at the I.L.L. high flux reactor. This low energy part of the energy spectrum presents a smooth connection with the energy spectra which have been recently reported above 7 MeV. The overall energy spectrum, which is known to be quasi-gaussian above 12 MeV, is slightly asymmetric at low energy, where the observed particles are 6% more than expected from a gaussian shape. As a consequence, all the values reported for /sup 235/ U for the rate of ..cap alpha..-accompanied fission compared to binary fission have to be multiplied by 1.06. This asymmetry is about 2 times less important than the one reported for /sup 252/Cf. No evidence was seen for any intense low energy component as reported before. The possible reasons for the existence of this asymmetry are discussed.

  7. (Studies of target fragmentation in intermediate energy, relativistic and ultra-relativistic nuclear collisions)

    Energy Technology Data Exchange (ETDEWEB)

    Loveland, W.D.

    1991-08-01

    The work described herein is part of a project involving the study of low energy (< 10 MeV/A), intermediate energy (10--100 MeV/A) and relativistic (> 250 MeV/A) heavy ion reactions. In the low energy regime, we published a monograph on the properties of the heaviest elements and used that publication as a basis for making a set of best'' semi-empirical predictions of heavy element decay properties. The intermediate energy research effort focussed upon the completion of studies already begun and the initiation of a number of new experiments. In our study of a interaction of 21 MeV/nucleon {sup 129}Xe with {sup 197}Au, we compared the characteristics of the observed deep inelastic phenomena with various models of dissipative reactions and found significant discrepancies between observations and predictions. These discrepancies seemed to be caused by an improper treatment of pre-equilibrium in the early stages of the collision. In our study of the relativistic interaction of 400 MeV/nucleon {sup 12}C with {sup 197}Au, we reported the first direct physical measurement of the properties of the spallation residues from a nucleus-nucleus collision. We found the residue energies to be much lower than those predicted by the intranuclear cascade model, indicating some substantial modifications of that model are needed. But, we also found, indications of significant, non-zero values of the residue transverse momentum, a finding that calls into question the interpretation of a number of radiochemical recoil studies of the kinematics of high energy reactions. A program of performing numerical simulations of intermediate and high energy nuclear collisions using the QMD model was initiated.

  8. The SPIDER fission fragment spectrometer for fission product yield measurements

    Energy Technology Data Exchange (ETDEWEB)

    Meierbachtol, K.; Tovesson, F. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Shields, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States); Arnold, C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Blakeley, R. [University of New Mexico, Albuquerque, NM 87131 (United States); Bredeweg, T.; Devlin, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hecht, A.A.; Heffern, L.E. [University of New Mexico, Albuquerque, NM 87131 (United States); Jorgenson, J.; Laptev, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mader, D. [University of New Mexico, Albuquerque, NM 87131 (United States); O' Donnell, J.M.; Sierk, A.; White, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2015-07-11

    The SPectrometer for Ion DEtermination in fission Research (SPIDER) has been developed for measuring mass yield distributions of fission products from spontaneous and neutron-induced fission. The 2E–2v method of measuring the kinetic energy (E) and velocity (v) of both outgoing fission products has been utilized, with the goal of measuring the mass of the fission products with an average resolution of 1 atomic mass unit (amu). The SPIDER instrument, consisting of detector components for time-of-flight, trajectory, and energy measurements, has been assembled and tested using {sup 229}Th and {sup 252}Cf radioactive decay sources. For commissioning, the fully assembled system measured fission products from spontaneous fission of {sup 252}Cf. Individual measurement resolutions were met for time-of-flight (250 ps FWHM), spacial resolution (2 mm FHWM), and energy (92 keV FWHM for 8.376 MeV). Mass yield results measured from {sup 252}Cf spontaneous fission products are reported from an E–v measurement.

  9. Fission modes in charged-particle induced fission

    Energy Technology Data Exchange (ETDEWEB)

    Matthies, A.; Kotte, R.; Seidel, W.; Stary, F.; Wohlfarth, D. (Zentralinstitut fuer Kernforschung, Rossendorf bei Dresden (German Democratic Republic))

    1990-12-01

    The population of the three fission modes predicted by Brosa's multi-channel fission model for the uranium region was studied in different fissioning systems. They were produced bombarding {sup 232}Th and {sup 238}U targets by light charged particles with energies slightly above the Coulomb barrier. Though the maximum excitation energy of the compound nucleus amounted to about 22 MeV, the influences of various spherical and deformed nuclear shells on the mass and total kinetic energy distributions of fission fragments are still pronounced. The larger variances of the total kinetic energy distributions compared to those of thermal neutron induced fission were explained by temperature dependent fluctuations of the amount and velocity of alteration of the scission point elongation of the fissioning system. From the ratio of these variances the portion of the potential energy dissipated among intrinsic degrees of freedom before scission was deduced for the different fission channels. It was found that the excitation remaining after pre-scission neutron emission is mainly transferred into intrinsic heat and less into pre-scission kinetic energy. (orig.).

  10. Population of bound excited states in intermediate-energy fragmentation reactions

    CERN Document Server

    Obertelli, A; Bazin, D; Campbell, C M; Cook, J M; Cottle, P D; Davies, A D; Dinca, D C; Glasmacher, T; Hansen, P G; Hoagland, T; Kemper, K W; Lecouey, J L; Müller, W F; Reynolds, R R; Roeder, B T; Terry, J R; Tostevin, J A; Yoneda, K; Zwahlen, H

    2006-01-01

    Fragmentation reactions with intermediate-energy heavy-ion beams exhibit a wide range of reaction mechanisms, ranging from direct reactions to statistical processes. We examine this transition by measuring the relative population of excited states in several sd-shell nuclei produced by fragmentation with the number of removed nucleons ranging from two to sixteen. The two-nucleon removal is consistent with a non-dissipative process whereas the removal of more than five nucleons appears to be mainly statistical.

  11. Neutron dose equivalent rate in intermediate energy heavy ion target area

    CERN Document Server

    Li Gui Sheng; Li Zong Wei; Su You Wu; Zhang Shu Mi

    2000-01-01

    The fluence rate distributions of neutrons emitted in the reactions of 50 MeV/u sup 1 sup 8 O-ion on thick Be, Cu, Au targets were measured with an activation method of threshold detectors and the neutron dose equivalent rate distributions at 1 m from the targets in intermediate energy heavy ion target area were obtained using the conversion coefficients for neutron fluence rate to ambient dose equivalent rate.

  12. [Studies in intermediate energy nuclear physics]. Technical progress report, [October 1, 1992--September 30, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, R.J.

    1993-10-01

    This report summarizes work carried out between October 1, 1992 and September 30, 1993 at the Nuclear Physics Laboratory of the University of Colorado, Boulder. The experimental program in intermediate-energy nuclear physics is very broadly based; it includes pion-nucleon and pion-nucleus studies at LAMPF and TRIUMF, kaon-nucleus scattering at the AGS, and equipment development for experiments at the next generation of accelerator facilities.

  13. Calculations for populations of selected isotopes in intermediate energy heavy ion collisions

    CERN Document Server

    Majumder, A

    2000-01-01

    We compute the populations of isotopes of Boron, Carbon and Nitrogen measured experimentally in intermediate energy heavy ion collisions. A two component soluble statistical model is used to find the initial populations of different nuclei at a finite temperature. These initial populations are both in particle stable and particle unstable states. The particle unstable states then decay. The final populations after these decays are computed and compared with experimental data.

  14. Isospin Effect on the Process of Multifragmentation and Dissipation at Intermediate Energy Heavy Ion Collisions

    CERN Document Server

    Liu Jian Ye; Zuo, W; Wang, S J; Zhao, Q; Guo, W J; Chen, B; Liu, Jian-Ye; Yang, Yan-Fang; Zuo, Wei; Wang, Shun-Jin; Zhao, Qiang; Guo, Wen-Jun; Chen, Bo

    2001-01-01

    In the simulation of intermediate energy heavy ion collisions by using the isospin dependent quantum molecular dynamics, the isospin effect on the process of multifragmentation and dissipation has been studied. It is found that the multiplicity of intermediate mass fragments $N_{imf}$ for the neutron-poor colliding system is always larger than that for the neutron-rich system, while the quadrupole of single particle momentum distribution $Q_{zz}$ for the neutron-poor colliding system is smaller than that of the neutron-rich system for all projectile-target combinations studied at the beam energies from about 50MeV/nucleon to 150MeV/nucleon. Since $Q_{zz}$ depends strongly on isospin dependence of in-medium nucleon-nucleon cross section and weakly on symmetry potential at the above beam energies, it may serve as a good probe to extract the information on the in-medium nucleon-nucleon cross section. The correlation between the multiplicity $N_{imf}$ of intermediate mass fragments and the total numer of charged ...

  15. "TIVAL" — A development in spectrum tailoring for intermediate-energy neutron beam production

    Science.gov (United States)

    Constantine, G.

    1989-07-01

    Beams of intermediate-energy neutrons produced by filtering offer significant advantages over thermal neutrons for boron neutron capture therapy. Preconditioning the spectrum within the reactor prior to filtering can increase the intensity and lower the mean neutron energy, to give reduced proton recoil damage in normal tissue. Aluminium with a small proportion of D 2O has been proposed as a spectrum shifter to achieve this. We describe here calculations that demonstrate considerable further softening of the spectrum by TIVAL, a mixture of aluminium together with small quantities of titanium and vanadium.

  16. The 2-ID-B intermediate-energy scanning X-ray microscope at the APS

    Energy Technology Data Exchange (ETDEWEB)

    McNulty, I.; Paterson, D.; Arko, J.; Erdmann, M.; Goetze, K.; Ilinski, P.; Mooney, T.; Vogt, S.; Xu, S. [Argonne National Lab., IL (United States); Frigo, S.P. [Chicago Univ., IL (United States). Dept. of Physics; Retsch, C.C. [Saint-Gobain Sekurit Deutschland (Germany); Stampfl, A.P.J. [Australian Nuclear Science and Technology Organisation, Div. Physics, Menai, NSW (Australia); Wang, Y. [X-Radia Inc., Concord, CA (United States)

    2002-08-01

    The intermediate-energy scanning x-ray microscope at beamline 2-ID-B at the Advanced Photon Source is a dedicated instrument for materials and biological research. The microscope uses a zone plate lens to focus coherent 1-4 keV x-rays to a 60 nm focal spot of 10{sup 9} photons/s onto the sample. It records simultaneous transmission and energy-resolved fluorescence images. We have used the microscope for nano-tomography of chips and micro-spectroscopy of cells. (authors)

  17. Intermediate energy proton stopping power for hydrogen molecules and monoatomic helium gas

    Science.gov (United States)

    Xu, Y. J.; Khandelwal, G. S.; Wilson, J. W.

    1984-01-01

    Stopping power in the intermediate energy region (100 keV to 1 MeV) was investigated, based on the work of Lindhard and Winther, and on the local plasma model. The theory is applied to calculate stopping power of hydrogen molecules and helium gas for protons of energy ranging from 100 keV to 2.5 MeV. Agreement with the experimental data is found to be within 10 percent. Previously announced in STAR as N84-16955

  18. Fission yield measurements at IGISOL

    Directory of Open Access Journals (Sweden)

    Lantz M.

    2016-01-01

    Full Text Available The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure relative independent fission yields. In some cases it is even possible to resolve isomeric states from the ground state, permitting measurements of isomeric yield ratios. So far the reactions U(p,f and Th(p,f have been studied using the IGISOL-JYFLTRAP facility. Recently, a neutron converter target has been developed utilizing the Be(p,xn reaction. We here present the IGISOL-technique for fission yield measurements and some of the results from the measurements on proton induced fission. We also present the development of the neutron converter target, the characterization of the neutron field and the first tests with neutron-induced fission.

  19. Ternary fission and cluster radioactivities

    CERN Document Server

    Poenaru, D N; Greiner, W; Gherghescu, R A; Hamilton, J H; Ramayya, A V

    2002-01-01

    Ternary fission yield for different kinds of light particle accompanied fission processes is compared to the Q-values for the corresponding cold phenomena, showing a striking correlation. The experimental evidence for the existence of a quasimolecular state in sup 1 sup 0 Be accompanied fission of sup 2 sup 5 sup 2 Cf may be explained using a three-center phenomenological model which generates a third minimum in the deformation energy at a separation distance very close to the touching point. This model is a natural extension of the unified approach to three groups of binary decay modes (cold fission, cluster radioactivities and alpha decay), illustrated by sup 2 sup 3 sup 4 U decay modes, and the alpha valley on the potential energy surfaces of sup 1 sup 0 sup 6 Te. New measurements of cluster decay modes, confirming earlier predictions within analytical superasymmetric fission model, are included in a comprehensive half-life systematics. (authors)

  20. Fission dynamics: The quest of a temperature dependent nuclear viscosity

    Directory of Open Access Journals (Sweden)

    Vardaci E.

    2013-12-01

    Full Text Available This contribution presents a journey within the open questions about the current use of a temperature dependent nuclear viscosity in models of nuclear fission and proposes an alternative experimental approach by using systems of intermediate fissility. This study is particularly relevant because: i systems of intermediate fissility offer a suitable framework since the intervals between the compound nucleus and scission point temperatures with increasing excitation energy are much smaller than in the case of heavier systems, ii the measurement of observables in the ER channel translates into a larger set of effective constraints for the models.

  1. Measurement of Fission Product Yields from Fast-Neutron Fission

    Science.gov (United States)

    Arnold, C. W.; Bond, E. M.; Bredeweg, T. A.; Fowler, M. M.; Moody, W. A.; Rusev, G.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Henderson, R.; Kenneally, J.; Macri, R.; McNabb, D.; Ryan, C.; Sheets, S.; Stoyer, M. A.; Tonchev, A. P.; Bhatia, C.; Bhike, M.; Fallin, B.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.

    2014-09-01

    One of the aims of the Stockpile Stewardship Program is a reduction of the uncertainties on fission data used for analyzing nuclear test data [1,2]. Fission products such as 147Nd are convenient for determining fission yields because of their relatively high yield per fission (about 2%) and long half-life (10.98 days). A scientific program for measuring fission product yields from 235U,238U and 239Pu targets as a function of bombarding neutron energy (0.1 to 15 MeV) is currently underway using monoenergetic neutron beams produced at the 10 MV Tandem Accelerator at TUNL. Dual-fission chambers are used to determine the rate of fission in targets during activation. Activated targets are counted in highly shielded HPGe detectors over a period of several weeks to identify decaying fission products. To date, data have been collected at neutron bombarding energies 4.6, 9.0, 14.5 and 14.8 MeV. Experimental methods and data reduction techniques are discussed, and some preliminary results are presented.

  2. GGA+U study of uranium mononitride: A comparison of the U-ramping and occupation matrix schemes and incorporation energies of fission products

    Science.gov (United States)

    Claisse, Antoine; Klipfel, Marco; Lindbom, Niclas; Freyss, Michel; Olsson, Pär

    2016-09-01

    Uranium mononitride is studied in the DFT + U framework. Its ground state is investigated and a study of the incorporation of diverse fission products in the crystal is conducted. The U-ramping and occupation matrix control (OMC) schemes are used to eliminate metastable states. Beyond a certain amount of introduced correlation, the OMC scheme starts to find a lower total energy. The OMC scheme is chosen for the second part of this study. Furthermore, the influence of the magnetic ordering is studied using the U-ramping method, showing that antiferromagnetic order is the most stable one when the U parameter is larger than 1.75 eV. The effect on the density of states is investigated and elastic constants are provided for comparison with other methods and experiments. The incorporation energies of fission products in different defect configurations are calculated and these energies are corrected to take into account the limited size of the supercell.

  3. Energy Dependence of Fission Product Yields from 235U, 238U and 239Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV

    Science.gov (United States)

    Gooden, M. E.; Arnold, C. W.; Becker, J. A.; Bhatia, C.; Bhike, M.; Bond, E. M.; Bredeweg, T. A.; Fallin, B.; Fowler, M. M.; Howell, C. R.; Kelley, J. H.; Krishichayan; Macri, R.; Rusev, G.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2016-01-01

    Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varying degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for 235U, 238U and 239Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed from the dual-fission chamber and gamma

  4. Energy Dependence of Fission Product Yields from 235U, 238U and 239Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Gooden, M. E.; Arnold, C. W.; Becker, J. A.; Bhatia, C.; Bhike, M.; Bond, E. M.; Bredeweg, T. A.; Fallin, B.; Fowler, M. M.; Howell, C. R.; Kelley, J. H.; Krishichayan,; Macri, R.; Rusev, G.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2016-01-01

    Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varying degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for 235U, 238U and 239Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed

  5. Multifragmentation in intermediate energy 129Xe-induced heavy-ion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Tso, Kin [Univ. of California, Berkeley, CA (United States)

    1996-05-01

    The 129Xe-induced reactions on natCu, 89Y, 165Ho, and 197Au at bombarding energies of E/A = 40 & 60 MeV have been studied theoretically and experimentally in order to establish the underlying mechanism of multifragmentation at intermediate energy heavy-Ion collisions. Nuclear disks formed in central heavy-ion collisions, as simulated by means of Boltzmann-like kinetic equations, break up into several fragments due to a new kind of Rayleigh-like surface instability. A sheet of liquid, stable in the limit of non-interacting surfaces, is shown to become unstable due to surface-surface interactions. The onset of this instability is determined analytically. A thin bubble behaves like a sheet and is susceptible to the surface instability through the crispation mode. The Coulomb effects associated with the depletion of charges in the central cavity of nuclear bubbles are investigated. The onset of Coulomb instability is demonstrated for perturbations of the radial mode. Experimental intermediate-mass-fragment multiplicity distributions for the 129Xe-induced reactions are shown to be binomial at each transverse energy. From these distributions, independent of the specific target, an elementary binary decay probability p can be extracted that has a thermal dependence. Thus it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with transverse energy implies a contraction of the emission time scale. The sensitivity of p to the lower Z threshold in the definition of intermediate-mass-fragments points to a physical Poisson simulations of the particle multiplicities show that the weak auto-correlation between the fragment multiplicity and the transverse energy does not distort a Poisson distribution into a binomial distribution. The effect of device efficiency on the experimental results has also been studied.

  6. Control of energy homeostasis: role of enzymes and intermediates of fatty acid metabolism in the central nervous system.

    Science.gov (United States)

    Wolfgang, Michael J; Lane, M Daniel

    2006-01-01

    The regulation of energy homeostasis is critical for normal physiology and survival. Energy flux must be rigorously monitored and adjusted to ensure that fuel intake and expenditure remain within acceptable limits. The central nervous system (CNS) is, in large part, responsible for conducting this energy-monitoring function and for integrating the numerous inputs. It has become evident that neurons of the CNS monitor and respond to levels of metabolic intermediates that reflect peripheral energy status. Intermediates in the fatty acid biosynthetic pathway have been implicated as hypothalamic signaling mediators that sense and respond to changes in circulating fuels. Genetic and pharmacologic manipulation of the enzymes of fatty acid metabolism have led to the hypothesis that neuronal metabolic intermediates affect neural outputs that modify both feeding behavior and energy expenditure. This review focuses on the regulatory roles of these enzymes and intermediates in the regulation of food intake and energy balance.

  7. Response to 'A comment on 'Signatures of fissile materials:High-energy gamma rays following fission,' by Zeev B. Alfassi'

    Energy Technology Data Exchange (ETDEWEB)

    Norman, Eric B.; Prussin, Stanley G.; Larimer, Ruth-Mary; Shugart, Howard; Browne, Edgardo; Smith, Alan R.; McDonald, Richard J.; Nitsche, Heino; Gupta, Puja; Frank, Michael I.; Gosnell, Thomas B.

    2004-06-03

    Prof. Alfassi has pointed out that radionuclides that are not fission products, but which emit {gamma} rays with energies E{sub {gamma}} > 3 MeV, can be produced by neutron irradiation. He suggested that the decays of such activation products would interfere with the identification of fissionable materials. However, the combination of the energy spectrum and the temporal variation of the fission product gamma rays can be used to distinguish fissionable material from other nuclides. The activation of nuclides that could produce interferences will depend upon the specifics of the cargo and, possibly, the local surroundings. As discussed in our original publication, in addition to the steel that Prof. Alfassi referred to in his Comment, we studied the activation of wood, polyethylene, aluminum, and sandstone. Activation by thermal neutrons will always occur, and Prof. Alfassi correctly points out that nuclides such as {sup 49}Ca and {sup 37}S can be formed in this way. These nuclides are representative of most potential interferences. Both {sup 48}Ca and {sup 36}S have very low isotopic abundances (0.187% and 0.02%, respectively) and small thermal neutron capture cross sections (0.20 barns and 0.98 barns, respectively). In addition, their half lives are more than an order of magnitude longer than the gross average observed from the fission products, and more than two orders of magnitude longer than the lifetimes of the shorter-lived fission products that contribute significantly to the total intensity in the energy range of interest. These differences make it possible to distinguish between fission products and thermal neutron activation products. Prof. Alfassi also pointed out that interferences, of which {sup 16}N is likely to be the most important, can be produced by fast neutron reactions. (As described in our original publication, we did not use a 14 MeV generator in our work.) Fortunately, a judicious choice of the source neutron energy can limit the extent of

  8. Solvent-dependent activation of intermediate excited states in the energy relaxation pathways of spheroidene.

    Science.gov (United States)

    Maiuri, Margherita; Polli, Dario; Brida, Daniele; Lüer, Larry; LaFountain, Amy M; Fuciman, Marcel; Cogdell, Richard J; Frank, Harry A; Cerullo, Giulio

    2012-05-14

    In carotenoids internal conversion between the allowed (S(2)) and forbidden (S(1)) excited states occurs on a sub-picosecond timescale; the involvement of an intermediate excited state(s) (S(x)) mediating the process is controversial. Here we use high time resolution (sub-20 fs) broadband (1.2-2.5 eV) pump-probe spectroscopy to study the solvent dependence of excited state dynamics of spheroidene, a naturally-occurring carotenoid with ten conjugated double bonds. In the high polarizability solvent, CS(2), we find no evidence of an intermediate state, and the traditional three-level (S(0), S(1), S(2)) model fully accounts for the S(2)→ S(1) process. On the other hand, in the low polarizability solvent, cyclohexane, we find that rapid (~30 fs) relaxation to an intermediate state, S(x), lying between S(1) and S(2) is required to account for the data. We interpret these results as due to a shift of the S(2) energy, which positions the state above or below the energy of S(x) in response to changes in solvent polarizability. This journal is © the Owner Societies 2012

  9. Monte Carlo Simulation to relate primary and final fragments mass and kinetic energy distribution from low energy fission of $^{234}U$

    CERN Document Server

    Montoya, M; Lobato, I

    2008-01-01

    The kinetic energy distribution as a function of mass of final fragments (m) from low energy fission of $^{234}U$, measured with the Lohengrin spectrometer by Belhafaf et al. presents a peak around m=108 and another around m = 122. The authors attribute the first peak to the evaporation of a large number of neutrons around the corresponding mass number; and the second peak to the distribution of the primary fragment kinetic energy. Nevertheless, the theoretical calculations related to primary distribution made by Faust et al. do not result in a peak around m = 122. In order to clarify this apparent controversy, we have made a numerical experiment in which the masses and the kinetic energy of final fragments are calculated, assuming an initial distribution of the kinetic energy without peaks on the standard deviation as function of fragment mass. As a result we obtain a pronounced peak on the standard deviation of the kinetic energy distribution around m = 109, a depletion from m = 121 to m = 129, and an small...

  10. Determination of the fission barrier height in fission of heavy radioactive beams induced by the (d,p)-transfer

    CERN Multimedia

    A theoretical framework is described, allowing to determine the fission barrier height using the observed cross sections of fission induced by the (d,p)-transfer with accuracy, which is not achievable in another type of low-energy fission of neutron-deficient nuclei, the $\\beta$-delayed fission. The primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission of...

  11. Modernizing the Fission Basis

    Science.gov (United States)

    Tonchev, Anton; Henderson, Roger; Schunck, Nicolas; Sroyer, Mark; Vogt, Ramona

    2016-09-01

    In 1939, Niels Bohr and John Wheeler formulated a theory of neutron-induced nuclear fission based on the hypothesis of the compound nucleus. Their theory, the so-called ``Bohr hypothesis,'' is still at the heart of every theoretical fission model today and states that the decay of a compound nucleus for a given excitation energy, spin, and parity is independent of its formation. We propose the first experiment to validate to 1-2% absolute uncertainties the practical consequences of the Bohr hypothesis during induced nuclear fission. We will compare the fission product yields (FPYs) of the same 240Pu compound nucleus produced via two different reactions (i) n+239Pu and (ii) γ+240 Pu. These high-precision FPYs measurements will be extremely beneficial for our fundamental understanding of the nuclear fission process and nuclear reactions from first principles. This work was performed under the auspices of US DOE by LLNL under Contract DE-AC52-07NA27344. Funding was provided via the LDRD-ERD-069 project.

  12. Comparative evaluation of solar, fission, fusion, and fossil energy resources. Part 5: Conclusions and recomendations

    Science.gov (United States)

    Williams, J. R.

    1974-01-01

    Air pollution resulting from the use of fossil fuels is discussed. Phenomena relating to the emission of CO2 such as the greenhouse effect and multiplier effect are explored. Particulate release is also discussed. The following recommendations are made for the elimination of fossil fuel combustion products in the United States: development of nuclear breeder reactors, use of solar energy systems, exploration of energy alternatives such as geothermal and fusion, and the substitution of coal for gas and oil use.

  13. Highly efficient spin-conversion effect leading to energy up-converted electroluminescence in singlet fission photovoltaics

    Science.gov (United States)

    Pandey, Ajay K.

    2015-01-01

    Free charge generation in donor-acceptor (D-A) based organic photovoltaic diodes (OPV) progresses through formation of charge-transfer (CT) and charge-separated (CS) states and excitation decay to the triplet level is considered as a terminal loss. On the other hand a direct excitation decay to the triplet state is beneficial for multiexciton harvesting in singlet fission photovoltaics (SF-PV) and the formation of CT-state is considered as a limiting factor for multiple triplet harvesting. These two extremes when present in a D-A system are expected to provide important insights into the mechanism of free charge generation and spin-character of bimolecular recombination in OPVs. Herein, we present the complete cycle of events linked to spin conversion in the model OPV system of rubrene/C60. By tracking the spectral evolution of photocurrent generation at short-circuit and close to open-circuit conditions we are able to capture spectral changes to photocurrent that reveal the triplet character of CT-state. Furthermore, we unveil an energy up-conversion effect that sets in as a consequence of triplet population build-up where triplet-triplet annihilation (TTA) process effectively regenerates the singlet excitation. This detailed balance is shown to enable a rare event of photon emission just above the open-circuit voltage (VOC) in OPVs.

  14. Measurement of the energy spectrum of {sup 252}Cf fission fragments using nuclear track detectors and digital image processing

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, G.; Golzarri, J. I. [UNAM, Instituto de Fisica, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Castano, V. M. [UNAM, Centro de Fisica Aplicada y Tecnologia Avanzada, Boulevard Juriquilla 3001, Santiago de Queretaro, 76230 Queretaro (Mexico); Gaso, I. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Mena, M.; Segovia, N. [UNAM, Instituto de Geofisica, Circuito de la Investigacion Cientifica, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2010-02-15

    The energy spectrum of {sup 252}Cf fission fragments was measured using nuclear track detectors and digital image analysis system. The detection material was fused silica glass. The detectors were chemically etched in an 8% HF solution. After experimenting with various etching time, it was found that the best resolution of the track diameter distribution was obtained after 30 minutes of etching. Both Gaussian and Lorentzian curves were fit to the track diameter distribution histograms and used to determine the basic parameters of the distribution of the light (N{sub L}) and heavy (N{sub H}) formed peaks and the minimum of the central valley (N{sub V}). Advantages of the method presented here include the fully-automated analysis process, the low cost of the nuclear track detectors and the simplicity of the nuclear track method. The distribution resolution obtained by this method is comparable with the resolution obtained by electronic analysis devices. The descriptive variables calculated were very close to those obtained by other methods based on the use of semiconductor detectors. (Author)

  15. Elastic and total cross sections for simple biomolecules in the intermediate energy range

    Directory of Open Access Journals (Sweden)

    Dhanoj Gupta

    2015-09-01

    Full Text Available The elastic and total cross sections for formaldehyde, acetaldehyde, acetone, 2-butanone and formamide are calculated using the spherical complex optical potential formalism in the intermediate energy range from 50 eV to 10 keV. These cross sections find application to various fields like radiation damage and biological sciences. The present results are compared with the available experimental and theoretical data and are found to give excellent agreement. The elastic cross sections reported for most of the targets in the present energy range are done for the first time. The energy dependence of the contribution of ionization and elastic cross section with respect to the total cross section and the correlation of total cross section with polarizability of the molecules are also studied.

  16. Elastic and total cross sections for simple biomolecules in the intermediate energy range

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Dhanoj; Naghma, Rahla; Antony, Bobby, E-mail: bka.ism@gmail.com [Atomic and Molecular Physics Lab, Department of Applied Physics, Indian School of Mines, Dhanbad 826004, JH (India)

    2015-09-15

    The elastic and total cross sections for formaldehyde, acetaldehyde, acetone, 2-butanone and formamide are calculated using the spherical complex optical potential formalism in the intermediate energy range from 50 eV to 10 keV. These cross sections find application to various fields like radiation damage and biological sciences. The present results are compared with the available experimental and theoretical data and are found to give excellent agreement. The elastic cross sections reported for most of the targets in the present energy range are done for the first time. The energy dependence of the contribution of ionization and elastic cross section with respect to the total cross section and the correlation of total cross section with polarizability of the molecules are also studied.

  17. (d,p)-transfer induced fission of heavy radioactive beams

    CERN Document Server

    Veselsky, Martin

    2012-01-01

    (d,p)-transfer induced fission is proposed as a tool to study low energy fission of exotic heavy nuclei. Primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission offers a possibility for systematic study the low energy fission of heavy exotic nuclei at the ISOLDE.

  18. Intermediate ionization continua for double charge exchange at high impact energies

    Science.gov (United States)

    Belkić, D.ževad

    1993-05-01

    We investigate the problem of two-electron capture from heliumlike atomic systems by bare nuclei ZP+(ZTe1,e2)i-->(ZPe1,e2)f+ZT at high incident energies, using the four-body formalism of the first- and second-order theories. Our goal is to establish the relative importance of the intermediate ionization continua of the two electrons in comparison with the usual direct path of the double electron transfer. For this purpose we presently introduce the boundary-corrected continuum-intermediate-state (BCIS) approximation, which preserves all the features of two-electron capture as a genuine four-body problem. The proposed second-order theory provides a fully adequate description of the fact that, in an intermediate stage of collision, both electrons move in the field of the two Coulomb centers. The previously devised boundary-corrected first Born (CB1) approximation can be obtained as a further simplification of the BCIS model if the invoked two-electron Coulomb waves are replaced by their long-range logarithmic phase factors defined in terms of the corresponding interaggregate separation R. The BCIS method is implemented on the symmetric resonant double charge exchange in collisions between α particles and He(1s2) at impact energies E>=900 keV. The obtained results for the differential and total cross sections are compared with the available experimental data and satisfactory agreement is recorded. As the incident energy increases, a dramatic improvement is obtained in going from the CB1 to the BCIS approximation, since the latter closely follows the measurement, whereas the former overestimates the observed total cross sections by two orders of magnitude.

  19. Complex fragment production in Kr-induced reactions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, A.; Colonna, M.; Di Toro, M. (Catania Univ. (Italy). Dipt. di Fisica INFN, Catania (Italy). Lab. Nazionale del Sud); Bonasera, A. (INFN, Catania (Italy)); Cavinato, M.; Gulminelli, F. (Milan Univ. (Italy). Dipt. di Fisica INFN, Milan (Italy)); Cunsolo, A. (Catania Univ. (Italy). Dipt. di Fisica INFN, Catania (Italy)); Di Leo, G.C. (Catania Univ. (Italy). Dipt. di Fisica)

    1991-07-15

    Several features of complex fragment production at intermediate energies can be understood from the coupling of a dynamical description, which takes into account entrance-channel properties, and a statistical decay of equilibrated primary sources. We discuss this point using two different models for the dynamics, both based on the idea of the competition between mean field and two-body effects in this intermediate-energy range. The importance of a slow emission of large clusters in the de-excitation stage is stressed, with the possibility of using a suitably extended evaporation code. Fragment yields and spectra are analysed for Kr-induced reactions on C, Al, Ti at 34.4 MeV/A and on Au at 43 MeV/A. The effects of a different equation of state (e.o.s.) used in microscopic calculations is analysed. A stiffer e.o.s. implies more stopping of the fragments. Finally, projectile-like fragments produced in the Kr+Au reaction at 200 MeV/A are analysed. The predictions of the participant-spectator model are confirmed in this energy range. (orig.).

  20. Energy dependence of fission-fragment mass distributions from strongly damped shape evolution

    Science.gov (United States)

    Randrup, J.; Möller, P.

    2013-12-01

    The recently developed treatment of Brownian shape evolution is refined to take account of the gradual decrease in microscopic effects as the nuclear excitation energy is raised. We construct effective potential-energy surfaces by multiplying the shell-plus-pairing correction term by a suppression factor that depends on the local excitation energy. While this approach is equivalent to the modification of the Fermi-gas level density parameter suggested by Ignatyuk [Sov. J. Nucl. Phys. 29, 450 (1979)], we adopt a more general functional form for the suppression factor, which is adjusted to measured charge yields for 234U(E*≈11MeV). The resulting model is benchmarked by comparison with 70 measured yields.

  1. Isospin Effect on Nuclear Stopping in Intermediate Energy Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By using the isospin dependent quantum molecular dynamics model (IQMD), we study the dependence of nuclear stopping Qzz/A and R in intermediate energy heavy ion collisions on system size, initial N/Z, isospin symmetry potential and the medium correction of two-body cross sections. We find the effect of initial N/Z ratio, isospin symmetry potential on stopping is weak. The excitation function of Qzz/A and R depends on the form of medium correction of two-body cross sections and the equation of state of nuclear matter (EOS). Our results show the behavior of the excitation function of Qzz/A and

  2. Nucleon and cluster knockout reactions induced in light nuclei by intermediate-energy protons

    Energy Technology Data Exchange (ETDEWEB)

    Vdovin, A.I.; Golovin, A.V.; Loshchakov, I.I.

    1987-11-01

    Experimental and theoretical studies of nucleon and cluster knockout reactions induced in light nuclei by intermediate-energy (30--150 MeV) protons are reviewed. The methods of theoretical analysis of knockout reactions are considered. The main attention is devoted to the t-matrix approximation with distorted waves. It is shown for the example of cluster knockout reactions how quasielastic and two-step processes can be coherently included in the matrix element when the t-matrix approximation is used.

  3. Quadrupole Collectivity beyond N=28: Intermediate-Energy Coulomb Excitation of Ar47,48

    Science.gov (United States)

    Winkler, R.; Gade, A.; Baugher, T.; Bazin, D.; Brown, B. A.; Glasmacher, T.; Grinyer, G. F.; Meharchand, R.; McDaniel, S.; Ratkiewicz, A.; Weisshaar, D.

    2012-05-01

    We report on the first experimental study of quadrupole collectivity in the very neutron-rich nuclei Ar47,48 using intermediate-energy Coulomb excitation. These nuclei are located along the path from doubly magic Ca to collective S and Si isotopes, a critical region of shell evolution and structural change. The deduced B(E2) transition strengths are confronted with large-scale shell-model calculations in the sdpf shell using the state-of-the-art SDPF-Uand EPQQM effective interactions. The comparison between experiment and theory indicates that a shell-model description of Ar isotopes around N=28 remains a challenge.

  4. Radiochemistry and the Study of Fission

    Energy Technology Data Exchange (ETDEWEB)

    Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-14

    These are slides from a lecture given at UC Berkeley. Radiochemistry has been used to study fission since it’ discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution. The following topics are covered: In the beginning: the discovery of fission; forensics using fission products: what can be learned from fission products, definitions of R-values and Q-values, fission bases, K-factors and fission chambers, limitations; the neutron energy dependence of the mass yield distribution (the two mode fission hypothesis); the influence of nuclear structure on the mass yield distribution. In summary: Radiochemistry has been used to study fission since it’s discovery. Radiochemical measurement of fission product yields have provided the highest precision data for developing fission models and for nuclear forensics. The two-mode fission hypothesis provides a description of the neutron energy dependence of the mass yield curve. However, data is still rather sparse and more work is needed near second and third chance fission. Radiochemical measurements have provided evidence for the importance of nuclear states in the compound nucleus in predicting the mass yield curve in the resonance region.

  5. Historical evolution of nuclear energy systems development and related activities in JAERI. Fission, fusion, accelerator utilization

    Energy Technology Data Exchange (ETDEWEB)

    Tone, Tatsuzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    Overview of the historical evolution of nuclear energy systems development and related activities in JAERI is given in the report. This report reviews the research and development for light water reactor, fast breeder reactor, high temperature gas reactor, fusion reactor and utilization of accelerator-based neutron source. (author)

  6. Nuclear fission, the energy of the future; La fision nuclear como energia del futuro

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Val, J. M.; Fernandez, J. A.; Leon, P. T.

    2002-07-01

    The design of new-generation nuclear power stations incorporates approaches and control systems which significantly reduce risk and waste generation, while enhancing an installation's performance. This article reviews current programs involving the world's advanced reactors,and other future systems such as rapid reproduction reactors, or those operating in sub-critical conditions as energy amplifier. (Author) 12 refs.

  7. Intermediate milling energy optimization to enhance the characteristics of barium hexaferrite magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hodaei, A.; Ataie, A., E-mail: aataie@ut.ac.ir; Mostafavi, E.

    2015-08-15

    Highlights: • Nano-sized BaFe{sub 12}O{sub 19} was successfully synthesized via a solid-state reaction. • Intermediate milling energy was optimized to improve BaFe{sub 12}O{sub 19} properties. • Minimum total energy of 93.7 kJ/g was necessary for formation of BaFe{sub 12}O{sub 19}. • Deviation from the optimum milling energy deteriorates the magnetic properties. - Abstract: Nano-sized barium hexaferrite particles were synthesized by mechanical activation of BaCO{sub 3} and Fe{sub 2}O{sub 3} powders mixture as starting materials. The effects of mechanical milling energy on the phase composition, morphology, thermal behavior and magnetic properties of the samples were systematically investigated by employing X-ray diffractometer, field emission scanning electron microscopy, differential thermal/thermo gravimetry analysis and vibrating sample magnetometer, respectively. The milling energy was calculated at five different levels using collision model. It was found that there is an optimum milling energy value for obtaining barium hexaferrite phase. The results revealed that applying a minimum total milling energy of 93.7 kJ/g was necessary for formation of almost single barium hexaferrite at a relatively low calcination temperature of 800 °C. FESEM micrograph of the above sample exhibited nano-size particles with a mean particle size of 80 nm. Further increase in milling energy leads to dramatic decrease in phase purity as well as magnetic characteristics of the samples. By increasing the milling energy from 93.7 to 671.9 kJ/g, saturation magnetization (M{sub s}) decreased from 22.5 to 0.39 emu/g, and also coercivity (H{sub c}) decreased from 4.28 to 1.46 kOe.

  8. Nucleon-nucleon resonances at intermediate energies using a complex energy formalism

    CERN Document Server

    Papadimitriou, G

    2015-01-01

    We apply our method of complex scaling, valid for a general class of potentials, in a search for nucleon-nucleon S-matrix poles up to 2 GeV laboratory kinetic energy. We find that the realistic potentials JISP16, constructed from inverse scattering, and chiral field theory potentials N$^3$LO and N$^2$LO$_{opt}$ support resonances in energy regions well above their fit regions. In some cases these resonances have widths that are narrow when compared with the real part of the S-matrix pole.

  9. Fe-substituted indium thiospinels: New intermediate band semiconductors with better absorption of solar energy

    Science.gov (United States)

    Chen, Ping; Chen, Haijie; Qin, Mingsheng; Yang, Chongyin; Zhao, Wei; Liu, Yufeng; Zhang, Wenqing; Huang, Fuqiang

    2013-06-01

    The indium thiospinels In2S3 and MgIn2S4 are promising host for the intermediated band (IB) photovoltaic materials due to their ideal band gap value. Here, the optical properties and electronic structure of Fe-doped In2S3 and MgIn2S4 have been investigated. All the Fe-substituted semiconductors exhibit two additional absorption bands at about 0.7 and 1.25 eV, respectively. The results of first-principles calculations revealed that the Fe substituted at the octahedral In site would introduce a partially filled IB into the band gap. Thanks to the formation of IB, the Fe-substituted semiconductors have the ability to absorb the photons with energies below the band gap. With the wide-spectrum absorption of solar energy, these materials possess potential applications in photovoltaic domain.

  10. Evolution of collectivity in the 78Ni region: Coulomb excitation of 74Ni at intermediate energies.

    Directory of Open Access Journals (Sweden)

    Marchi T.

    2014-03-01

    Full Text Available The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic observables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope (64Ni towards the 78Ni nucleus where the large neutron excess coincides with a double shell closure. In this framework, we have recently performed an experiment with the goal to extract the B(E2; 0+ → 2+ value for the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment: preliminary results are discussed.

  11. A Common Optical Potential for $^{4}$He+$^{12}$C at Intermediate Energies

    CERN Document Server

    Hu, Li-Yuan; Hou, Ying-Wei; Liu, Hui-Lan

    2016-01-01

    A common optical potential for $^4$He+$^{12}$C at intermediate bombarding energies, which is essential in analyzing exotic nuclei with $^4$He clusters, was obtained based on the S\\~{a}o Paulo potential (SPP). Among systematic optical potentials for $^4$He+$^{12}$C, this potential has the merit of using a fixed imaginary part of Woods-Saxon form. By optical-model calculations, this potential reproduced the experimental elastic scattering angular distributions of $^4$He+$^{12}$C well within the energy range of 26\\,$A$--60\\,$A$ MeV. It was also applied successfully in calculations of the breakup reactions of $^6$Li+$^{12}$C and $^6$He+$^{12}$C with a three-body continuum discretized coupled-channels method.

  12. Nuclear Many-Body Theory of Electroweak Interactions with Nuclei at Intermediate Energies

    Energy Technology Data Exchange (ETDEWEB)

    Nieves, J. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain); Amaro, J.E. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain); Valverde, M. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain)

    2005-02-15

    The Quasi-Elastic (QE) contribution of the nuclear inclusive electron model developed in reference [Nucl. Phys. A627 (1997) 543; ibidem Nucl. Phys. A627 (1997) 598] is extended to the study of electroweak Charged Current (CC) induced nuclear reactions at intermediate energies of interest for future neutrino oscillation experiments. Long range nuclear (RPA) correlations, Final State Interaction (FSI) and Coulomb corrections are included within the model. RPA correlations are shown to play a crucial role in the whole range of neutrino energies, up to 500 MeV, studied in this work. Predictions for inclusive muon capture for different nuclei through the Periodic Table and for the reactions C12({nu}{sub {mu}},{mu}{sup -})X and C12({nu}{sub e},e{sup -})X near threshold are also given.

  13. Nuclear Power from Fission Reactors. An Introduction.

    Science.gov (United States)

    Department of Energy, Washington, DC. Technical Information Center.

    The purpose of this booklet is to provide a basic understanding of nuclear fission energy and different fission reaction concepts. Topics discussed are: energy use and production, current uses of fuels, oil and gas consumption, alternative energy sources, fossil fuel plants, nuclear plants, boiling water and pressurized water reactors, the light…

  14. Sub-library of Updated Fission Barrier Parameters(CENPL-FBP2)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The fission barrier parameters are important to determine the fission character of a nucleus. The fission barrier parameters and fission level densities are key ingredients in calculations of not only fission cross section but also various cross sections, and spectra for the fissile nuclides, even heavy nuclides at higher incident energies. It is necessaries that the accuracy of fission barrier parameters requires even higher, and nuclides with fission barrier parameters can cover even wider nuclear range.

  15. Dynamical collective potential energy landscape: its impact on the competition between fusion and quasi-fission in a heavy fusing system

    CERN Document Server

    Díaz-Torres, A

    2006-01-01

    A realistic microscopically-based quantum approach to the competition between fusion and quasi-fission in a heavy fusing system is applied to several reactions leading to $^{256}$No. Fusion and quasi-fission are described in terms of a diffusion process of nuclear shapes through a dynamical collective potential energy landscape which is initially diabatic and gradually becomes adiabatic. The microscopic ingredients of the theory are obtained with a realistic two-center shell model based on Woods-Saxon potentials. The results indicate that (i) the diabatic effects play a very important role in the onset of fusion hindrance for heavy systems, and (ii) very asymmetric reactions induced by closed shell nuclei seem to be the best suited to synthesize the heaviest compound nuclei.

  16. Fission modelling with FIFRELIN

    Energy Technology Data Exchange (ETDEWEB)

    Litaize, Olivier; Serot, Olivier; Berge, Leonie [CEA, DEN, DER, SPRC, Saint Paul Lez Durance (France)

    2015-12-15

    The nuclear fission process gives rise to the formation of fission fragments and emission of particles (n,γ, e{sup -}). The particle emission from fragments can be prompt and delayed. We present here the methods used in the FIFRELIN code, which simulates the prompt component of the de-excitation process. The methods are based on phenomenological models associated with macroscopic and/or microscopic ingredients. Input data can be provided by experiment as well as by theory. The fission fragment de-excitation can be performed within Weisskopf (uncoupled neutron and gamma emission) or a Hauser-Feshbach (coupled neutron/gamma emission) statistical theory. We usually consider five free parameters that cannot be provided by theory or experiments in order to describe the initial distributions required by the code. In a first step this set of parameters is chosen to reproduce a very limited set of target observables. In a second step we can increase the statistics to predict all other fission observables such as prompt neutron, gamma and conversion electron spectra but also their distributions as a function of any kind of parameters such as, for instance, the neutron, gamma and electron number distributions, the average prompt neutron multiplicity as a function of fission fragment mass, charge or kinetic energy, and so on. Several results related to different fissioning systems are presented in this work. The goal in the next decade will be i) to replace some macroscopic ingredients or phenomenological models by microscopic calculations when available and reliable, ii) to be a support for experimentalists in the design of detection systems or in the prediction of necessary beam time or count rates with associated statistics when measuring fragments and emitted particle in coincidence iii) extend the model to be able to run a calculation when no experimental input data are available, iv) account for multiple chance fission and gamma emission before fission, v) account for

  17. Fission modelling with FIFRELIN

    Science.gov (United States)

    Litaize, Olivier; Serot, Olivier; Berge, Léonie

    2015-12-01

    The nuclear fission process gives rise to the formation of fission fragments and emission of particles (n,γ , e-) . The particle emission from fragments can be prompt and delayed. We present here the methods used in the FIFRELIN code, which simulates the prompt component of the de-excitation process. The methods are based on phenomenological models associated with macroscopic and/or microscopic ingredients. Input data can be provided by experiment as well as by theory. The fission fragment de-excitation can be performed within Weisskopf (uncoupled neutron and gamma emission) or a Hauser-Feshbach (coupled neutron/gamma emission) statistical theory. We usually consider five free parameters that cannot be provided by theory or experiments in order to describe the initial distributions required by the code. In a first step this set of parameters is chosen to reproduce a very limited set of target observables. In a second step we can increase the statistics to predict all other fission observables such as prompt neutron, gamma and conversion electron spectra but also their distributions as a function of any kind of parameters such as, for instance, the neutron, gamma and electron number distributions, the average prompt neutron multiplicity as a function of fission fragment mass, charge or kinetic energy, and so on. Several results related to different fissioning systems are presented in this work. The goal in the next decade will be i) to replace some macroscopic ingredients or phenomenological models by microscopic calculations when available and reliable, ii) to be a support for experimentalists in the design of detection systems or in the prediction of necessary beam time or count rates with associated statistics when measuring fragments and emitted particle in coincidence iii) extend the model to be able to run a calculation when no experimental input data are available, iv) account for multiple chance fission and gamma emission before fission, v) account for the

  18. Two neutron correlations in photo-fission

    Science.gov (United States)

    Dale, D. S.; Kosinov, O.; Forest, T.; Burggraf, J.; Stave, S.; Warren, G.; Starovoitova, V.

    2016-09-01

    A large body of experimental work has established the strong kinematical correlation between fission fragments and fission neutrons. Here, we report on the progress of investigations of the potential for strong two neutron correlations arising from the nearly back-to-back nature of the two fission fragments that emit these neutrons in the photo-fission process. In initial measurements, a pulsed electron linear accelerator was used to generate bremsstrahlung photons that impinged upon an actinide target, and the energy and opening angle distributions of coincident neutrons were measured using a large acceptance neutron detector array. A planned comprehensive set of measurements of two neutron correlations in the photo-fission of actinides is expected to shed light on several fundamental aspects of the fission process including the multiplicity distributions associated with the light and heavy fission fragments, the nuclear temperatures of the fission fragments, and the mass distribution of the fission fragments as a function of energy released. In addition to these measurements providing important nuclear data, the unique kinematics of fission and the resulting two neutron correlations have the potential to be the basis for a new tool to detect fissionable materials. A key technical challenge of this program arises from the need to perform coincidence measurements with a low duty factor, pulsed electron accelerator. This has motivated the construction of a large acceptance neutron detector array, and the development of data analysis techniques to directly measure uncorrelated two neutron backgrounds.

  19. Theoretical Description of the Fission Process

    Energy Technology Data Exchange (ETDEWEB)

    Witold Nazarewicz

    2003-07-01

    The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process.

  20. Development of ODS FeCrAl for Compatibility in Fusion and Fission Energy Applications

    Science.gov (United States)

    Pint, B. A.; Dryepondt, S.; Unocic, K. A.; Hoelzer, D. T.

    2014-12-01

    Oxide dispersion strengthened (ODS) FeCrAl alloys with 12-15% Cr are being evaluated for improved compatibility with Pb-Li for a fusion energy application and with high temperature steam for a more accident-tolerant light water reactor fuel cladding application. A 12% Cr content alloy showed low mass losses in static Pb-Li at 700°C, where a LiAlO2 surface oxide formed and inhibited dissolution into the liquid metal. All the evaluated compositions formed a protective scale in steam at 1200°C, which is not possible with ODS FeCr alloys. However, most of the compositions were not protective at 1400°C, which is a general and somewhat surprising problem with ODS FeCrAl alloys that is still being studied. More work is needed to optimize the alloy composition, microstructure and oxide dispersion, but initial promising tensile and creep results have been obtained with mixed oxide additions, i.e. Y2O3 with ZrO2, HfO2 or TiO2.

  1. The role of non-elastic nuclear processes for intermediate-energy protons in silicon targets

    Energy Technology Data Exchange (ETDEWEB)

    Hormaza, Joel Mesa, E-mail: jmesa@ibb.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Botucatu, SP (Brazil); Garcia, Cesar E., E-mail: cgarcia@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), Havana (Cuba); Arruda Neto, Joao D.T.; Rodrigues, Tulio E., E-mail: arruda@if.usp.br, E-mail: tulio@if.usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica; Schelin, Hugo R.; Denyak, Valery, E-mail: schelin@utfpr.edu.br, E-mail: denyak@gmail.com [Instituto de Pesquisa Pele Pequeno Principe, Curitiba, PR (Brazil); Paschuck, Sergei A.; Evseev, Ivan, E-mail: sergei@utfpr.edu.br, E-mail: evseev@utfpr.edu.br [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

    2013-07-01

    The transportation of energetic ions in bulk matter is of direct interest in several areas including shielding against ions originating from either space radiations or terrestrial accelerators, cosmic ray propagation studies in galactic medium, or radiobiological effects resulting from the work place or clinical exposures. For carcinogenesis, terrestrial radiation therapy, and radiobiological research, knowledge of beam composition and interactions is necessary to properly evaluate the effects on human and animal tissues. For the proper assessment of radiation exposures both reliable transport codes and accurate input parameters are needed. In the last years efforts have been increasing in order to develop more effective models to describe and predict the damages induced by radiation in electronic devices. In this sense, the interaction of protons with those devices, particularly which operate in space, is a topic of paramount importance, mainly because although the majority of them are made with silicon, experimental data on p+Si nuclear processes is very sparse. In this work we have used a new quite sophisticated Monte Carlo multicollisional intranuclear cascade (MCMC) code for pre-equilibrium emission, plus de-excitation of residual nucleus by two ways: evaporation of particles (mainly nucleons, but also composites) and possibly fragmentation/fission in the case of heavy residues, in order to study some observable of nuclear interaction of protons between 100-200 MeV in a {sup 28}Si target. The code has been developed with very recent improvements that take into account Pauli blocking effects in a novel and more precise way, as well as a more rigorous energy balance, an energy stopping time criterion for pre-equilibrium emission and the inclusion of deuteron, triton and 3He emissions in the evaporation step, which eventually concurs with fragmentation/break-up stage. The fragment mass distributions, as well as the multiplicities and the spectra of secondary

  2. Effect of fission fragment on thermal conductivity via electrons with an energy about 0.5 MeV in fuel rod gap

    Directory of Open Access Journals (Sweden)

    F Golian

    2017-02-01

    Full Text Available The heat transfer process from pellet to coolant is one of the important issues in nuclear reactor. In this regard, the fuel to clad gap and its physical and chemical properties are effective factors on heat transfer in nuclear fuel rod discussion. So, the energy distribution function of electrons with an energy about 0.5 MeV in fuel rod gap in Busherhr’s VVER-1000 nuclear reactor was investigated in this paper. Also, the effect of fission fragments such as Krypton, Bromine, Xenon, Rubidium and Cesium on the electron energy distribution function as well as the heat conduction via electrons in the fuel rod gap have been studied. For this purpose, the Fokker- Planck equation governing the stochastic behavior of electrons in absorbing gap element has been applied in order to obtain the energy distribution function of electrons. This equation was solved via Runge-Kutta numerical method. On the other hand, the electron energy distribution function was determined by using Monte Carlo GEANT4 code. It was concluded that these fission fragments have virtually insignificant effect on energy distribution of electrons and therefore, on thermal conductivity via electrons in the fuel to clad gap. It is worth noting that this result is consistent with the results of other experiments. Also, it is shown that electron relaxation in gap leads to decrease in thermal conductivity via electrons

  3. Fission yield studies at the IGISOL facility

    Energy Technology Data Exchange (ETDEWEB)

    Penttilae, H.; Elomaa, V.V.; Eronen, T.; Hakala, J.; Jokinen, A.; Kankainen, A.; Moore, I.D.; Rahaman, S.; Rinta-Antila, S.; Rissanen, J.; Saastamoinen, A.; Weber, C.; Aeystoe, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); Rubchenya, V. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation)

    2012-04-15

    Low-energy-particle-induced fission is a cost-effective way to produce neutron-rich nuclei for spectroscopic studies. Fission has been utilized at the IGISOL to produce isotopes for decay and nuclear structure studies, collinear laser spectroscopy and precision mass measurements. The ion guide technique is also very suitable for the fission yield measurements, which can be performed very efficiently by using the Penning trap for fission fragment identification and counting. The proton- and neutron-induced fission yield measurements at the IGISOL are reviewed, and the independent isotopic yields of Zn, Ga, Rb, Sr, Cd and In in 25MeV deuterium-induced fission are presented for the first time. Moving to a new location next to the high intensity MCC30/15 light-ion cyclotron will allow also the use of the neutron-induced fission to produce the neutron rich nuclei at the IGISOL in the future. (orig.)

  4. Estimation of the radiation strength, dose equivalent and mean gamma-ray energy form p+ sup 2 sup 3 sup 8 U fission products

    CERN Document Server

    Kawakami, H

    2003-01-01

    On 100 isobars from 72 to 171 mass number, the radiation strength, dose equivalent and mean gamma-ray energy from p+ sup 2 sup 3 sup 8 U fission products at Tandem accelerator facility were estimated on the basis of data of proton induced fission mass yield by T. Tsukada. In order to control radiation, the decay curves of radiation of each mass after irradiation were estimated and illustrated. These calculation results showed 1) the peak of p+ sup 2 sup 3 sup 8 U fission products is 101 and 133 mass number. 2) gamma-ray strength of target ion source immediately after irradiation is 3.12x10 sup 1 sup 1 (Radiation/s) when it repeated 4 cycles of UC sub 2 (2.6 g/cm sup 2) target radiated by 30 MeV and 3 mu A proton for 5 days and then cooled for 2 days. It decreased to 3.85x10 sup 1 sup 0 and 6.7x10 sup 9 (Radiation/s) after one day and two weeks cooling, respectively. 3) Total dose equivalent is 3.8x10 sup 4 (mu S/h) at 1 m distance without shield. 4) There are no problems on control the following isobars, beca...

  5. Crossover from a fission-evaporation scenario towards multifragmentation in spallation reactions

    CERN Document Server

    Napolitani, P

    2006-01-01

    Mostly for the purpose of applications for the energy and the environment and for the design of sources of neutrons or exotic nuclides, intense research has been dedicated to spallation, induced by protons or light projectiles at incident energies of around 1 GeV. In this energy range, while multifragmentation has still a minor share in the total reaction cross section, it was observed to have, together with fission, a prominent role in the production and the kinematics of intermediate-mass fragments, so as to condition the whole production of light and heavy nuclides. The experimental observables we dispose of attribute rather elusive properties to the intermediate-mass fragments and do not allow to classify them within one exclusive picture which is either multifragmentation or fission. Indeed, these two decay mechanisms, driven by different kinds of instabilities, exhibit behaviours which are closely comparable. High-resolution measurements of the reaction kinematics trace the way for probing finer feature...

  6. Isospin Effect on Nuclear Stopping in Intermediate Energy Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    李庆峰; 李祝霞

    2002-01-01

    By using the isospin-dependent quantum molecular dynamics model, we study the dependence of nuclear stopping Qzz/A and R in intermediate energy heavy ion collisions on system size, initial N/Z, isospin symmetry potential and the medium correction of two-body cross sections. We find the effect of the initial N/Z ratio and isospinsymmetry potential on stopping is weak. The excitation function of Qzz/A and R depends on the form of medium correction of two-body cross sections, the equation ofstate of nuclear matter. Our results show that the behaviour of the excitation function of Qzz/A and R can provide clearer information of the isospin dependence of the medium correction of two-body cross sections

  7. Excitation of vibrational quanta in furfural by intermediate-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Costa, R. F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, 09210-580 São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Lima, M. A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); and others

    2015-12-14

    We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°–90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.

  8. Absolute Differential Cross Sections for Elastic Scattering of Electrons from CO at Intermediate and High Energies

    Institute of Scientific and Technical Information of China (English)

    SHI De-Heng; LIU Yu-Fang; SUN Jin-Feng; YANG Xiang-Dong; ZHU Zun-Lue

    2005-01-01

    @@ The additivity rule model together with the complex optical model potential correlated by the concept of bonded atoms, which considers the overlapping effect of electron clouds between two atoms in a molecule, is firstly employed to calculate the absolute differential cross sections for electrons scattered by carbon monoxide at intermediate and high energies at the Hartree-Fock level. A comparison of elastic differential cross section results, obtained by using the correlated complex optical model potential, with the available experimental data,shows a significant improvement over the uncorrelated ones. The differential cross sections obtained by using the correlated complex optical model potential are in very good agreement with the experimental data. It is shown that the additivity rule model together with the correlated complex optical model potential is suitable for the calculations of the absolute differential cross sections of e-CO scattering.

  9. Probing core polarization around 78Ni: intermediate energy Coulomb excitation of 74Ni

    Directory of Open Access Journals (Sweden)

    Marchi T.

    2013-12-01

    We have recently measured the B(E2; 0+ → 2+ of the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment performed at the National Superconducting Cyclotron Laboratory of the Michigan State University. The 74Ni secondary beam has been produced by fragmentation of 86Kr at 140 AMeV on a thick Be target. Selected radioactive fragments impinged on a secondary 197Au target where the measurement of the emitted γ-rays allows to extract the Coulomb excitation cross section and related structure information. Preliminary B(E2 values do not point towards an enhancement of the transition matrix element and the comparison to what was already measured by Aoi and co-workers in [1] opens new scenarios in the interpretation of the shell evolution of the Z=28 isotopes.

  10. On the search for a (n,f cross-section reference at intermediate energies

    Directory of Open Access Journals (Sweden)

    Duran I.

    2017-01-01

    Full Text Available The (n,f cross-sections proposed as references by the IAEA for 235U, 238U and 209Bi are compared with a new analysis that combines the measurements performed at CERN-n_TOF of their cross-section ratios with new calculations done using Monte Carlo codes based on phenomenological models INCL+ +, GEMINI+ +, and ABLA07. The calculations are cross-checked with those for the (p,f reactions, where experimental values are available. We have evaluated in this way the (n,f cross sections for 238U, 235U and 209Bi, in the intermediate energy region going from 190 MeV to 2 GeV. Our results definitively discard the JENDL/HE-2007 evaluations above 300 MeV, falling inside the confidence corridor proposed by IAEA but for the points around 300–400 MeV where a discrepancy is to be noticed.

  11. Intermediate pyrolysis of biomass energy pellets for producing sustainable liquid, gaseous and solid fuels.

    Science.gov (United States)

    Yang, Y; Brammer, J G; Mahmood, A S N; Hornung, A

    2014-10-01

    This work describes the use of intermediate pyrolysis system to produce liquid, gaseous and solid fuels from pelletised wood and barley straw feedstock. Experiments were conducted in a pilot-scale system and all products were collected and analysed. The liquid products were separated into an aqueous phase and an organic phase (pyrolysis oil) under gravity. The oil yields were 34.1 wt.% and 12.0 wt.% for wood and barley straw, respectively. Analysis found that both oils were rich in heterocyclic and phenolic compounds and have heating values over 24 MJ/kg. The yields of char for both feedstocks were found to be about 30 wt.%, with heating values similar to that of typical sub-bituminous class coal. Gas yields were calculated to be approximately 20 wt.%. Studies showed that both gases had heating values similar to that of downdraft gasification producer gas. Analysis on product energy yields indicated the process efficiency was about 75%.

  12. An Apparatus for the Measurement of Various Scattering Processes in Intermediate Energy, Ion - Atom Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Kvale, T. J.; Seely, D. G.

    1998-07-01

    This paper summarizes the main features of an apparatus constructed at the University of Toledo for the study of various scattering processes in intermediate energy, ion - atom collisions. The main purpose of this facility is to provide experimental data which serve as benchmarks to test current scattering theories for those processes. Recent measurements of single electron detachment (SED) and double electron detachment (DED) total cross sections for 5-50 keV H{sup -} ions incident on noble gases and for 10-50 keV H{sup -} ions incident on CH{sub 4} molecules were conducted in this laboratory. As a result of an analysis of the scattered beam growth curves, information about other charge-changing cross sections in the hydrogen-atom (molecule) collision systems were obtain, as well.

  13. Systematics of intermediate-energy single-nucleon removal cross sections

    CERN Document Server

    Tostevin, J A

    2014-01-01

    There is now a large and increasing body of experimental data and theoretical analyses for reactions that remove a single nucleon from an intermediate-energy beam of neutron- or proton-rich nuclei. In each such measurement, one obtains the inclusive cross section for the population of all bound final states of the mass A-1 reaction residue. These data, from different regions of the nuclear chart, and that involve weakly- and strongly-bound nucleons, are compared with theoretical expectations. These calculations include an approximate treatment of the reaction dynamics and shell-model descriptions of the projectile initial state, the bound final states of the residues, and the single-particle strengths computed from their overlap functions. The results are discussed in the light of recent data, more exclusive tests of the eikonal dynamical description, and calculations that take input from more microscopic nuclear structure models.

  14. Excitation of vibrational quanta in furfural by intermediate-energy electrons

    Science.gov (United States)

    Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; García, G.; Blanco, F.; Brunger, M. J.

    2015-12-01

    We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°-90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.

  15. Fully microscopic description of elastic and inelastic scattering at intermediate incident energies

    Directory of Open Access Journals (Sweden)

    Minomo Kosho

    2016-01-01

    Full Text Available We aim for fully microscopic understanding of many-body nuclear reactions starting from two- and three-nucleon forces based on chiral effective field theory (Ch-EFT. We first construct a g-matrix with the nuclear forces based on Ch-EFT using Brueckner-Hartree-Fock theory, in which the three-nucleon force effects are represented through the density dependence of the g-matrix. Then, the folding model and microscopic coupled-channels method with the g-matrix are applied to nucleon-nucleus and nucleus-nucleus scattering at intermediate incident energies. This new microscopic framework well describes the elastic and inelastic cross sections with no ad-hoc parameters. In addition, the three-nucleon force and coupled-channels effects on many-body nuclear reactions are clarified.

  16. Intermediate-energy Coulomb excitation of 104Sn: Moderate E2 strength decrease approaching 100Sn

    CERN Document Server

    Doornenbal, P; Aoi, N; Matsushita, M; Obertelli, A; Steppenbeck, D; Wang, H; Audirac, L; Baba, H; Bednarczyk, P; Boissinot, S; Ciemala, M; Corsi, A; Furumoto, T; Isobe, T; Jungclaus, A; Lapoux, V; Lee, J; Matsui, K; Motobayashi, T; Nishimura, D; Ota, S; Pollacco, E C; Sakurai, H; Santamaria, C; Shiga, Y; Sohler, D; Taniuchi, R

    2013-01-01

    The reduced transition probability B(E2) of the first excited 2+ state in the nucleus 104Sn was measured via Coulomb excitation in inverse kinematics at intermediate energies. A value of 0.163(26) e^2b^2 was extracted from the absolute cross-section on a Pb target, while the method itself was verified with the stable 112Sn isotope. Our result deviates significantly from the earlier reported value of 0.10(4) e^2b^2 and corresponds to a moderate decrease of excitation strength relative to the almost constant values observed in the proton-rich, even-A 106-114Sn isotopes. Present state-of-the-art shell-model predictions, which include proton and neutron excitations across the N=Z=50 shell closures as well as standard polarization charges, underestimate the experimental findings

  17. A rapid multi-device wireless power transfer scheme using an intermediate energy storage

    Science.gov (United States)

    Yoon, C. S.; Nam, S. S.; Cho, S. H.

    2016-04-01

    We introduce a new time-division multiplex wireless power transfer (TDM-WPT) scheme for charging multiple devices with a single transmitter. More specifically, our proposed scheme adopts the intermediate energy storage (IES) circuit which enables storing the received energy from the source temporarily and then supplying it to the load. Thus, by adopting the IES, the receiver can charge the battery with the stored energy in the IES even while the receiver is not performing the direct charging process (from the transmitter). This allows charging multiple receivers simultaneously in a virtual manner, and it eventually leads to the reduction of overall charging time. For the theoretical verification, we analyse the performance of our proposed scheme based on the identical environment and in some selected results. We show that with our proposed scheme the required total charging time can be reduced compared to the conventional TDM-WPT. We also consider practical load (battery charger) requirements which change continuously. We present the simple guidelines for some key design parameters such as the optimal capacity of the IES and the proper number of receivers. Note that we additionally present the sample IES circuit and the related circuit simulation to show the detailed operation and the feasibility of the proposed scheme.

  18. The Fission of thorium with Alpha Particles

    Energy Technology Data Exchange (ETDEWEB)

    Newton, Amos S.

    1948-10-15

    Soon after the discovery of fission, Meitner, Bretscher and Cook found differences in the decay of various chemical fractions separated from uranium irradiated with slow neutrons and thorium irradiated with fast neutrons respectively and suggested that a difference existed in the distribution of fission products in the two cases. In 1940, Turner suggested that the distribution in various modes of fission should be investigated. The fact that elements such as tin, cadmium, palladium, and silver were found in fast neutron and deuteron fission of uranium and thorium before they were found in slow neutron fission of uranium suggested that the middle region of the distribution was raised as the energy of the incident particle was increased. Since the compound nucleus formed in the fission of thorium with alpha particles is U{sup 236}, the same compound nucleus formed in the fission of U{sup 235} with neutrons, it is of interest to study the fission of thorium with alphas and compare the resulting distribution of fission products with that found with uranium with slow and thorium with fast neutrons. Any difference between the various results where the same compound nucleus is formed must be due to differences in energy content and possible differences in distribution of the nucleons in the compound nucleus at the time of fission.

  19. Radiochemical studies on nuclear fission at Trombay

    Indian Academy of Sciences (India)

    Asok Goswami

    2015-08-01

    Since the discovery of nuclear fission in the year 1939, both physical and radiochemical techniques have been adopted for the study of various aspects of the phenomenon. Due to the ability to separate individual elements from a complex reaction mixture with a high degree of sensitivity and selectivity, a chemist plays a significant role in the measurements of mass, charge, kinetic energy, angular momentum and angular distribution of fission products in various fissioning systems. At Trombay, a small group of radiochemists initiated the work on radiochemical studies of mass distribution in the early sixties. Since then, radiochemical investigations on various fission observables have been carried out at Trombay in , , and heavy-ion-induced fissions. An attempt has been made to highlight the important findings of such studies in this paper, with an emphasis on medium energy and heavy-ion-induced fission.

  20. Ideological Fission

    DEFF Research Database (Denmark)

    Christiansen, Steen Ledet

    ; it is a materialisation of an ideological fission which attempts to excise certain ideological constructions, yet paradoxically casting them in a form that is recognizable and familiar. The monstrous metonomy which is used shows us glimpses of a horrid being, intended to vilify the attack on New York City. However......, it is a being which is reminiscent of earlier monsters - from Godzilla to The Blob. It is evident that the Cloverfield monster is a paradoxical construction which attempts to articulate fear and loathing about terrorism, but ends up trapped in an ideological dead-end maze, unable to do anything other than...

  1. MCNP6 Simulation of Light and Medium Nuclei Fragmentation at Intermediate Energies

    Energy Technology Data Exchange (ETDEWEB)

    Mashnik, Stepan Georgievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kerby, Leslie Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-05-22

    MCNP6, the latest and most advanced LANL Monte Carlo transport code, representing a merger of MCNP5 and MCNPX, is actually much more than the sum of those two computer codes; MCNP6 is available to the public via RSICC at Oak Ridge, TN, USA. In the present work, MCNP6 was validated and verified (V&V) against different experimental data on intermediate-energy fragmentation reactions, and results by several other codes, using mainly the latest modifications of the Cascade-Exciton Model (CEM) and of the Los Alamos version of the Quark-Gluon String Model (LAQGSM) event generators CEM03.03 and LAQGSM03.03. It was found that MCNP6 using CEM03.03 and LAQGSM03.03 describes well fragmentation reactions induced on light and medium target nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below, and can serve as a reliable simulation tool for different applications, like cosmic-ray-induced single event upsets (SEU’s), radiation protection, and cancer therapy with proton and ion beams, to name just a few. Future improvements of the predicting capabilities of MCNP6 for such reactions are possible, and are discussed in this work.

  2. Long-term residual radioactivity in an intermediate-energy proton linac

    Science.gov (United States)

    Blaha, J.; La Torre, F. P.; Silari, M.; Vollaire, J.

    2014-07-01

    A new 160 MeV H- linear accelerator (LINAC4) is being installed at CERN to replace the present 50 MeV LINAC2 as proton injector of the PS Booster (PSB). During operation, the accelerator components will be activated by the beam itself and by the secondary radiation field. Detailed Monte Carlo simulations, for various beam energies and several decay times, were performed to predict the residual radioactivity in the main accelerator components and to estimate the residual dose rate inside the tunnel. The results of this study will facilitate future dismantling, handling and storage of the activated parts and consequently minimize the radiation dose to involved workers. The component activation was also compared with the exemption limits given in the current Swiss legislation and to the CERN design values, in order to make predictions for the future storage and disposal of radioactive waste. The airborne radioactivity induced by particles escaping the beam dump and the activation of the beam dump cooling water circuit were also quantified. The aim of this paper is to provide data of sufficiently general interest to be used for similar studies at other intermediate-energy proton accelerator facilities.

  3. Fully differential cross sections for low to intermediate energy perpendicular plane ionization of xenon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, G., E-mail: ghanshyam.purohit@spsu.ac.in; Singh, P.; Patidar, V.

    2014-12-15

    Highlights: • We present triply differential cross section (TDCS) results for the perpendicular plane ionization of xenon atoms. • The TDCS has been calculated in the modified distorted wave Born approximation formalism. • The effects of target polarization and post collision interaction have also been included. • The polarization potential, higher order effects and PCI has been found to be useful in the description of TDCS. - Abstract: Triple differential cross section (TDCS) results are reported for the perpendicular plane ionization of Xe (5p) at incident electron energies 5 eV, 10 eV, 20 eV, and 40 eV above ionization potential. The modified distorted wave Born approximation formalism with first as well as the second order Born terms has been used to calculate the TDCS. Effects of target polarization and post collision interaction have also been included. We compare the (e, 2e) TDCS results of our calculation with the recent available experimental data and theoretical results and discuss the process contributing to structure seen in the differential cross section. It has been observed from the present study that the second order effect and target polarization make significant contribution in description of collision dynamics of xenon at the low and intermediate energy for the perpendicular emission of electrons.

  4. Measurement of reaction cross section for proton-rich nuclei (A<30) at intermediate energies

    CERN Document Server

    Zhang, H Y; Ren Zhong Zhou; Ma, Y G; Jiang, W Z; Zhu, Z Y; Cai, X Z; Fang, D Q; Zhong, C; Yu Li Ping; Wei, Y B; Zhan, W L; Guo, Z Y; Xiao, G Q; Wang, J S; Wang, J C; Wang, Q J; Li, J X; Wang, M; Chen, Z Q

    2002-01-01

    Radioactive ion beams were produced through the projectile fragmentation induced by 69 MeV/ nucleon sup 3 sup 6 Ar primary beam on a sup 9 Be target. Measurements of reaction cross sections (sigma sub R 's) for 44 nuclei with A<30 (mostly proton-rich), on carbon were performed on RIBLL (Radioactive Ion Beam Line in Lanzhou) of HIRFL (Heavy Ion Research Facility in Lanzhou) at intermediate energies around 30 MeV/nucleon by a transmission method. The experimental sigma sub R values for sup 2 sup 3 Al and sup 2 sup 7 P are abnormally large compared with their neighboring nuclei. Together with the previous experimental facts such as the binding energy and ground state data, it suggests anomalously large matter root-mean-square radii and proton halo structure in sup 2 sup 3 Al and in sup 2 sup 7 P. There is an enhancement for the sigma sub R of sup 1 sup 7 F + sup 1 sup 2 C compared with the neighboring isotopes. Considering that the ground state of sup 1 sup 7 F is 1d sub 5 sub / sub 2 , this can indicate that...

  5. Research on Nuclear Reaction Network Equation for Fission Product Nuclides

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Nuclear Reaction Network Equation calculation system for fission product nuclides was developed. With the system, the number of the fission product nuclides at different time can be calculated in the different neutron field intensity and neutron energy spectra

  6. Study of nuclear reactions involving heavy nuclei and intermediate- and high-energy protons and an application in nuclear reactor physics (ADS); Estudo das reacoes nucleares envolvendo nucleos pesados e protons a energias intermediarias e altas de uma aplicacao em fisica de reatores nucleares (ADS)

    Energy Technology Data Exchange (ETDEWEB)

    Matuoka, Paula Fernanda Toledo

    2016-07-01

    In the present work, intermediate- and high-energy nuclear reactions involving heavy nuclei and protons were studied with the Monte Carlo CRISP (Rio - Ilheus - Sao Paulo Collaboration) model. The most relevant nuclear processes studied were intranuclear cascade and fission-evaporation competition. Preliminary studies showed fair agreement between CRISP model calculation and experimental data of multiplicity of evaporated neutrons (E < 20 MeV) from the p(1200 MeV) + {sup 208}Pb reaction and of spallation residues from the p(1000 MeV) + {sup 208}Pb reaction. The investigation of neutron multiplicity from proton-induced fission of {sup 232}Th up to 85 MeV showed that it was being overestimated by CRISP model; on the other hand, fission cross section were being underestimated. This behavior is due to limitations of the intranuclear cascade model for low-energies (around 50 MeV). The p(1200 MeV) + {sup 208}Pb reaction was selected for the study of a spallation neutron source. High-energy neutrons (E > 20 MeV) were emitted mostly in the intranuclear cascade stage, while evaporation presented larger neutron multiplicity. Fission cross section of 209 mb and spallation cross section of 1788 mb were calculated both in agreement with experimental data. The fission process resulted in a symmetric mass distribution. Another Monte Carlo code, MCNP, was used for radiation transport in order to understand the role of a spallation neutron source in a ADS (Accelerator Driven System) nuclear reactor. Initially, a PWR reactor was simulated to study the isotopic compositions in spent nuclear fuel. As a rst attempt, a spallation neutron source was adapted to an industrial size nuclear reactor. The results showed no evidence of incineration of transuranic elements and modifications were suggested. (author)

  7. Advanced Space Fission Propulsion Systems

    Science.gov (United States)

    Houts, Michael G.; Borowski, Stanley K.

    2010-01-01

    Fission has been considered for in-space propulsion since the 1940s. Nuclear Thermal Propulsion (NTP) systems underwent extensive development from 1955-1973, completing 20 full power ground tests and achieving specific impulses nearly twice that of the best chemical propulsion systems. Space fission power systems (which may eventually enable Nuclear Electric Propulsion) have been flown in space by both the United States and the Former Soviet Union. Fission is the most developed and understood of the nuclear propulsion options (e.g. fission, fusion, antimatter, etc.), and fission has enjoyed tremendous terrestrial success for nearly 7 decades. Current space nuclear research and technology efforts are focused on devising and developing first generation systems that are safe, reliable and affordable. For propulsion, the focus is on nuclear thermal rockets that build on technologies and systems developed and tested under the Rover/NERVA and related programs from the Apollo era. NTP Affordability is achieved through use of previously developed fuels and materials, modern analytical techniques and test strategies, and development of a small engine for ground and flight technology demonstration. Initial NTP systems will be capable of achieving an Isp of 900 s at a relatively high thrust-to-weight ratio. The development and use of first generation space fission power and propulsion systems will provide new, game changing capabilities for NASA. In addition, development and use of these systems will provide the foundation for developing extremely advanced power and propulsion systems capable of routinely and affordably accessing any point in the solar system. The energy density of fissile fuel (8 x 10(exp 13) Joules/kg) is more than adequate for enabling extensive exploration and utilization of the solar system. For space fission propulsion systems, the key is converting the virtually unlimited energy of fission into thrust at the desired specific impulse and thrust

  8. Numerical comparison between deep water and intermediate water depth expressions applied to a wave energy converter

    Directory of Open Access Journals (Sweden)

    Pedro Beirão

    2015-09-01

    Full Text Available The energy that can be captured from the sea waves and converted into electricity should be seen as a contribution to decrease the excessive dependency and growing demand of fossil fuels. Devices suitable to harness this kind of renewable energy source and convert it into electricity—wave energy converters (WECs—are not yet commercially competitive. There are several types of WECs, with different designs and working principles. One possible classification is their distance to the shoreline and thus their depth. Near-shore devices are one of them since they are typically deployed at intermediate water depth (IWD. The selection of the WEC deployment site should be a balance between several parameters; water depth is one of them. Another way of classifying WECs is grouping them by their geometry, size and orientation. Considering a near-shore WEC belonging to the floating point category, this paper is focused on the numerical study about the differences arising in the power captured from the sea waves when the typical deep water (DW assumption is compared with the more realistic IWD consideration. Actually, the production of electricity will depend, among other issues, on the depth of the deployment site. The development of a dynamic model including specific equations for the usual DW assumption as well as for IWD is also described. Derived equations were used to build a time domain simulator (TDS. Numerical results were obtained by means of simulations performed using the TDS. The objective is to simulate the dynamic behavior of the WEC due to the action of sea waves and to characterize the wave power variations according with the depth of the deployment site.

  9. Proceedings of the workshop on program options in intermediate-energy physics. Volume 1. Summary and panel reports

    Energy Technology Data Exchange (ETDEWEB)

    Allred, J.C.; Talley, B. (comps.)

    1980-05-01

    A Workshop on Program Options in Intermediate-Energy Physics sponsored by the US Department of Energy was held at Los Alamos Scientific Laboratory, August 20 to 31, 1979. The scope of the workshop included all laboratories in intermediate-energy physics, worldwide, and all of these sent representatives to the workshop. The workshop addressed itself to the critical questions on nuclear and particle physics and how they can best be investigated by intermediate-energy accelerators. Among the questions that the workshop members considered were: (1) what are the important physics topics which might be understood through research on these accelerators in the next 10 years. These topics include, but are not restricted to, fundamental interactions and symmetries in particle physics, and nuclear modes of motion, structure, and reaction mechanisms; (2) what experiments should be undertaken to carry out the program. What are the kinematical conditions, accuracies, resolutions, and other parameters required to obtain the desired knowledge; (3) which accelerators are best suited for each experiment. What work at other laboratories (low-, intermediate-, or high-energy) could be undertaken to complement and/or supplement the proposed LAMPF program; and (4) what new facility capabilities should be explored for the long-term future. The workshop was divided into small panels in order to promote effective interchange of ideas. After reports to other panels and plenary sessions, the panelists prepared reports stating the results of their deliberations. These reports comprise the principal part of Volume I.

  10. Fundamental Fission Research with the NIFFTE Time Projection Chamber

    Science.gov (United States)

    Kleinrath, Verena; Niffte Collaboration

    2013-10-01

    The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) has developed a novel instrument for fission research - a Time Projection Chamber (TPC), which enables detailed tracking of charged particles emitted in neutron-induced fission. While the primary goal of the project is to measure fission cross sections with unprecedented precision, the TPC can also facilitate more fundamental fission studies. The detector's high efficiency (4-pi acceptance) and precise tracking capabilities (including energy deposition) provide a large amount of valuable information. Recent data collected during engineering runs using a U238/U235 target will be used to generate fission fragment angular distributions and yields as a function of incident neutron energy. These experimental results can lend insight into the evolution of nuclear shapes with respect to energy on the path to scission and therefore immediately drive fission theory development. Preliminary angular distributions and yields using the NIFFTE TPC will be presented. Neutron Induced Fission Fragment Tracking Experiment.

  11. Total reaction cross sections in CEM and MCNP6 at intermediate energies

    Science.gov (United States)

    Kerby, Leslie M.; Mashnik, Stepan G.

    2015-08-01

    Accurate total reaction cross section models are important to achieving reliable predictions from spallation and transport codes. The latest version of the Cascade Exciton Model (CEM) as incorporated in the code CEM03.03, and the Monte Carlo N-Particle transport code (MCNP6), both developed at Los Alamos National Laboratory (LANL), each use such cross sections. Having accurate total reaction cross section models in the intermediate energy region (∼ 50 MeV to ∼ 5 GeV) is very important for different applications, including analysis of space environments, use in medical physics, and accelerator design, to name just a few. The current inverse cross sections used in the preequilibrium and evaporation stages of CEM are based on the Dostrovsky et al. model, published in 1959. Better cross section models are available now. Implementing better cross section models in CEM and MCNP6 should yield improved predictions for particle spectra and total production cross sections, among other results. Our current results indicate this is, in fact, the case.

  12. X-ray experiments for Space applications in intermediate energy range

    CERN Document Server

    Yadav, Vipin K; Nandi, Anuj; Palit, Sourav

    2009-01-01

    X-ray experiments in the intermediate energy range (1-50 keV) are carried out at the Indian Centre for Space Physics (ICSP), Kolkata for space application. The purpose is to carry out developmental studies of space instruments to observe energetic phenomena from compact objects (black hole and compact stars) and active stars and their testing and evaluation. The testing/evaluation setup primarily consists of an X-ray generator, various X-ray imaging masks, an X-ray imager (CMOS) and an X-ray spectrometer (Si-PIN photo-diode). The X-ray generator (Mo target) operates in 1-50 kV anode voltage, and 1-30 mA beam current. A 45 feet long shielded collimator is used to collimate the beam which leads to the detector chamber having a 30 arc-sec angular diameter. Two types of imaging masks are used - conventional Coded Aperture Masks (CAM) and Tungsten Fresnel half-period zone-plates (ZPs) having angular resolutions of a few tens of arc-sec. The Moire fringe pattern produced by the composite shadows of two ZPs is inver...

  13. Modeling interactions of intermediate-energy neutrons in a plastic scintillator array with GEANT4

    Energy Technology Data Exchange (ETDEWEB)

    Kohley, Z., E-mail: zkohley@gmail.com [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Lunderberg, E.; DeYoung, P.A. [Department of Physics, Hope College, Holland, MI 49423 (United States); Roeder, B.T. [LPC-Caen, ENSICAEN, IN2P3/CNRS et Universite de Caen, 14050 Caen cedex (France); Baumann, T. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Christian, G.; Mosby, S.; Smith, J.K.; Snyder, J.; Spyrou, A.; Thoennessen, M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2012-08-01

    A Monte Carlo simulation of a large-area neutron time-of-flight detector, built on the GEANT4 framework, has been compared with an experimental measurement of the {sup 16}B{yields}{sup 15}B+n decay produced from a 55 MeV/u{sup 17}C beam. The ability of the Monte Carlo simulation to reproduce the intermediate-energy neutron interactions within the detector has been explored using both the stock GEANT4 physics processes and a custom neutron interaction model, MENATE{sub R}. The stock GEANT4 physics processes were unable to reproduce the experimental observables, while excellent agreement was obtained through the inclusion of the MENATE{sub R} model within GEANT4. The differences between the two approaches are shown to be related to the modeling of the neutron-carbon inelastic reactions. Additionally, the use of MENATE{sub R} provided accurate reproduction of experimental signals associated with neutron scattering within the detector. These results provide validation of the Monte Carlo simulation for modeling measurements of multiple neutrons where the identification and removal of false neutron signals, due to multiple neutron scattering, are required.

  14. Total Reaction Cross Sections in CEM and MCNP6 at Intermediate Energies

    CERN Document Server

    Kerby, Leslie M

    2015-01-01

    Accurate total reaction cross section models are important to achieving reliable predictions from spallation and transport codes. The latest version of the Cascade Exciton Model (CEM) as incorporated in the code CEM03.03, and the Monte Carlo N-Particle transport code (MCNP6), both developed at Los Alamos National Laboratory (LANL), each use such cross sections. Having accurate total reaction cross section models in the intermediate energy region ($\\sim$50 MeV to $\\sim$5 GeV) is very important for different applications, including analysis of space environments, use in medical physics, and accelerator design, to name just a few. The current inverse cross sections used in the preequilibrium and evaporation stages of CEM are based on the Dostrovsky {\\it et al.} model, published in 1959. Better cross section models are available now. Implementing better cross section models in CEM and MCNP6 should yield improved predictions for particle spectra and total production cross sections, among other results. Our current...

  15. Isospin Effect of Coulomb Interaction on Momentum Dissipation in Intermediate Energy Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Ye; GUO Wen-Jun; XING Yong-Zhong; Li Xi-Guo

    2004-01-01

    We investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. We also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon-nucleon cross section.In this case, Coulomb interaction does not change obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon-nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon-nucleon cross section and weakly on the symmetry potential.

  16. Effect of nuclear viscosity on fission process

    Energy Technology Data Exchange (ETDEWEB)

    Li Shidong; Kuang Huishun; Zhang Shufa; Xing Jingru; Zhuo Yizhong; Wu Xizhen; Feng Renfa

    1989-02-01

    According to the fission diffusion model, the deformation motion of fission nucleuses is regarded as a diffusion process of quasi-Brownian particles under fission potential. Through simulating such Brownian motion in two dimensional phase space by Monte-Carlo mehtod, the effect of nuclear visocity on Brownian particle diffusion is studied. Dynamical quanties, such as fission rate, kinetic energy distribution on scission, and soon are numerically calculated for various viscosity coefficients. The results are resonable in physics. This method can be easily extended to deal with multi-dimensional diffusion problems.

  17. Nuclear Stopping as A Probe to In-medium Nucleon-nucleon Cross Section in Intermediate Energy Heavy Ion Collisions

    CERN Document Server

    Liu Jian Ye; Wang, S J; Zuo, W; Zhao, Q; Yang Yong Feng; Liu, Jian-Ye; Guo, Wen-Jun; Wang, Shun-Jin; Zuo, Wei; Zhao, Qiang; Yang, Yan-Fang

    2001-01-01

    Using an isospin-dependent quantum molecular dynamics, nuclear stopping in intermediate heavy ion collisions has been studied. The calculation has been done for colliding systems with different neutron-proton ratios in beam energy ranging from 15MeV/u to 150MeV/u. It is found that, in the energy region from above Fermi energy to 150MeV/u, nuclear stopping is very sensitive to the isospin dependence of in-medium nucleon-nucleon cross section, but insensitive to symmetry potential. From this investigation, we propose that nuclear stopping can be used as a new probe to extract the information on the isospin dependence of in-medium nucleon-nucleon cross section in intermediate energy heavy ion collisions.

  18. Intermediate steps towards the 2000-Watt society in Switzerland: an energy-economic scenario analysis[Dissertation 17314

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, T. F

    2007-07-01

    In this dissertation by Thorsten Frank Schulz the intermediate steps necessary to realise the 2000-Watt Society in Switzerland are examined. An analysis of an energy-economic scenario shows that the 2000-Watt Society should be seen as a long-term goal. According to the author, the major changes required to allow the implementation of this project concern energy-transformation and energy-demand technologies. Electricity will, according to the author, play an important role in a service-oriented society in the future. In such a transformation even intermediate steps are associated with considerable expense. The aims of the 2000-Watt Society project are listed. Energy and CO{sub 2} balances for the domestic and transport sectors are presented and discussed. Complementary analyses are presented concerning fuel cells and wood-based fuel technologies. Finally, the implications of the 2000-Watt society and the effects of technological change are summarised and an outlook is presented.

  19. Energy dependent sticking coefficients of trimethylamine on Si(001)-Influence of the datively bonded intermediate state on the adsorption dynamics

    Science.gov (United States)

    Lipponer, M. A.; Reutzel, M.; Dürr, M.; Höfer, U.

    2016-11-01

    The adsorption dynamics of the datively bonded trimethylamine (TMA) on Si(001) was investigated by means of molecular beam techniques. The initial sticking probability s0 of TMA on Si(001) was measured as a function of kinetic energy at two different surface temperatures (230 and 550 K). At given surface temperature, s0 was found to decrease with increasing kinetic energy (0.1 to 0.6 eV) indicating a non-activated reaction channel. At increased surface temperature, s0 is reduced due to the onset of desorption into the gas phase. The energy dependence of s0 is compared to the results for the adsorption of tetrahydrofuran (THF) on Si(001), which reacts via a datively bonded intermediate into a covalently bound final state. As s0 follows the same energy dependence both for TMA and THF, the datively bonded intermediate state is concluded to dominate the reaction dynamics in the latter case as well.

  20. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    R A Gherghescu; D N Poenaru

    2015-09-01

    The macroscopic–microscopic method is extended to calculate the deformation energy and penetrability for binary nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped daughter and emitted fragment nuclei. The macroscopic part is obtained using the Yukawa-plus-exponential potential. The microscopic shell and pairing corrections are obtained using the Strutinsky and BCS approaches and the cranking formulae yield the inertia tensor. Finally, the WKB method is used to calculate penetrabilities and spontaneous fission half-lives. Calculations are performed for the decay of 282,292120 nuclei.

  1. Microscopic dynamical description of proton-induced fission with the Constrained Molecular Dynamics (CoMD) Model

    CERN Document Server

    Vonta, N; Veselsky, M; Bonasera, A

    2015-01-01

    The microscopic description of nuclear fission still remains a topic of intense basic research. Un- derstanding nuclear fission, apart from a theoretical point of view, is of practical importance for energy production and the transmutation of nuclear waste. In nuclear astrophysics, fission sets the upper limit to the nucleosynthesis of heavy elements via the r-process. In this work we initiated a systematic study of intermediate energy proton-induced fission using the Constrained Molecu- lar Dynamics (CoMD) code. The CoMD code implements an effective interaction with a nuclear matter compressibility of K=200 (soft EOS) with several forms of the density dependence of the nucleon-nucleon symmetry potential. Moreover, a constraint is imposed in the phase-space occu- pation for each nucleon restoring the Pauli principle at each time step of the collision. A proper choice of the surface parameter of the effective interaction has been made to describe fission. In this work, we present results of fission calculation...

  2. Prompt fission neutron spectrum of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Capote, R. [International Atomic Energy Agency, Vienna (Austria); Chen, Y. -J. [China Institute of Atomic Energy, Beijing (China); Hambsch, F. J. [European Commission, Joint Research Centre - IRRM, Geel (Belgium); Jurado, B. [CENBG, CNRS/IN2P3, Gradignan (France); Kornilov, N. [Ohio Univ., Athens, OH (United States); Lestone, J. P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Litaize, O. [CEA, DEN, DER, SPRC, Saint-Paul-Lez-Durance (France); Morillon, B. [CEA, DAM, DIF, Arpajon (France); Neudecker, D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oberstedt, S. [European Commission, Joint Research Centre - IRRM, Geel (Belgium); Ohsawa, T. [Kinki Univ., Osaka-fu (Japan); Otuka, N. [International Atomic Energy Agency, Vienna (Austria); Pronyaev, V. G. [Institute of Physics and Power Engineering, Obninsk (Russian Federation); Saxena, A. [Bhabha Atomic Research Centre, Mumbai (India); Schmidt, K. H. [CENBG, CNRS/IN2P3, Gradignan (France); Serot, O. [CEA, DEN, DER, SPRC, Saint-Paul-Lez-Durance (France); Shcherbakov, O. A. [Petersburg Nuclear Physics Institute of NRC " Kurchatov Institute" , Gatchina (Russian Federation); Shu, N. -C. [China Institute of Atomic Energy, Beijing (China); Smith, D. L. [Argonne National Lab. (ANL), Argonne, IL (United States); Talou, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trkov, A. [International Atomic Energy Agency, Vienna (Austria); Tudora, A. C. [Univ. of Bucharest, Magurele (Romania); Vogt, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Davis, CA (United States); Vorobyev, A. S. [Petersburg Nuclear Physics Institute of NRC " Kurchatov Institute" , Gatchina (Russian Federation)

    2016-01-06

    Here, the energy spectrum of prompt neutron emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) "Evaluation of Prompt Fission Neutron Spectra of Actinides" was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei.

  3. Correlation measurements of fission-fragment properties

    Science.gov (United States)

    Oberstedt, S.; Belgya, T.; Billnert, R.; Borcea, R.; Cano-Ott, D.; Göök, A.; Hambsch, F.-J.; Karlsson, J.; Kis, Z.; Martinez, T.; Oberstedt, A.; Szentmiklosi, L.; Takác, K.

    2010-10-01

    For the development of future nuclear fission applications and for a responsible handling of nuclear waste the a-priori assessment of the fission-fragments' heat production and toxicity is a fundamental necessity. The success of an indispensable modelling of the fission process strongly depends on a good understanding of the particular mechanism of scission, the mass fragmentation and partition of excitation energy. Experimental observables are fission-fragment properties like mass- and energy-distributions, and the prompt neutron as well as γ-ray multiplicities and emission spectra. The latter quantities should preferably be known as a function of fragment mass and excitation energy. Those data are highly demanded as published by the OECD-NEA in its high priority data request list. With the construction of the double (v, E) spectrometer VERDI we aim at measuring pre- and post-neutron masses directly and simultaneously to avoid prompt neutron corrections. From the simultaneous measurement of pre- and post-neutron fission-fragment data the prompt neutron multiplicity may then be inferred fully correlated with fragment mass yield and total kinetic energy. Using an ultra-fast fission event trigger spectral prompt fission γ-ray measurements may be performed. For that purpose recently developed lanthanum-halide detectors, with excellent timing characteristics, were coupled to the VERDI spectrometer allowing for a very good discrimination of fission γ-rays and prompt neutrons due to their different time-of-flight.

  4. Correlation measurements of fission-fragment properties

    Directory of Open Access Journals (Sweden)

    Oberstedt A.

    2010-10-01

    Full Text Available For the development of future nuclear fission applications and for a responsible handling of nuclear waste the a-priori assessment of the fission-fragments’ heat production and toxicity is a fundamental necessity. The success of an indispensable modelling of the fission process strongly depends on a good understanding of the particular mechanism of scission, the mass fragmentation and partition of excitation energy. Experimental observables are fission-fragment properties like mass- and energy-distributions, and the prompt neutron as well as γ-ray multiplicities and emission spectra. The latter quantities should preferably be known as a function of fragment mass and excitation energy. Those data are highly demanded as published by the OECD-NEA in its high priority data request list. With the construction of the double (v, E spectrometer VERDI we aim at measuring pre- and post-neutron masses directly and simultaneously to avoid prompt neutron corrections. From the simultaneous measurement of pre- and post-neutron fission-fragment data the prompt neutron multiplicity may then be inferred fully correlated with fragment mass yield and total kinetic energy. Using an ultra-fast fission event trigger spectral prompt fission γ-ray measurements may be performed. For that purpose recently developed lanthanum-halide detectors, with excellent timing characteristics, were coupled to the VERDI spectrometer allowing for a very good discrimination of fission γ-rays and prompt neutrons due to their different time-of-flight.

  5. Impact of density-dependent symmetry energy and Coulomb interactions on the evolution of intermediate mass fragments

    Indian Academy of Sciences (India)

    Karan Singh Vinayak; Suneel Kumar

    2014-03-01

    Within the framework of isospin-dependent quantum molecular dynamics (IQMD) model, we demonstrate the evolution of intermediate mass fragments in heavy-ion collisions. In this paper, we study the time evolution, impact parameter, and excitation energy dependence of IMF production for the different forms of density-dependent symmetry energy. The IMF production and charge distribution show a minor but considerable sensitivity towards various forms of densitydependent symmetry energy. The Coulomb interactions affect the IMF production significantly at peripheral collisions. The IMF production increases with the stiffness of symmetry energy.

  6. Asymmetric Fission in the 78Kr+40Ca reactions at 5.5 MeV/nucleon

    Directory of Open Access Journals (Sweden)

    Roy R.

    2012-02-01

    Full Text Available The cross section, kinetic energy distribution and angular distribution of fragments with atomic number 3 ≤ Z ≤ 28 emitted in the reaction 78Kr + 40Ca at the bombarding energy of 5.5 MeV/nucleon and coincidence between light charged particles and fragments were measured by means of the 4π-INDRA array to study the decay mechanism of medium mass excited nucleus. Global features indicate a high degree of relaxation and are compatible with a binary fission from compound nucleus. The mean value of the kinetic energy distributions of fragments indicates dominance of Coulomb interaction, while the width of the distribution signals large fluctuations. Inclusive cross-section distributions of fragments with charge 3 ≤ Z ≤ 28 are bell-shaped and a strong even-odd-staggering (o-es is observed for 3 ≤ Z ≤ 12. Coincidence measurements suggest that the light partners in very asymmetric fission are emitted at excitation energies below the particle emission thresholds. Data were confronted to the predictions of statistical model describing the decay of compound nuclei by emission of light particles and fragments. Calculations assuming spherical fission fragments and finite-range liquid drop fission barriers are not able to explain the experimental features. Attempts have been made to improve the agreement with experimental data. The analysis indicates the strong influence of the shape parameterization of the potential energy surface in describing the fission process of intermediate mass compound nuclei.

  7. Feasibility of using intermediate x-ray energies for highly conformal extracranial radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Peng; Yu, Victoria; Nguyen, Dan; Demarco, John; Low, Daniel A.; Sheng, Ke, E-mail: ksheng@mednet.ucla.edy [Department of Radiation Oncology, University of California Los Angeles, California 90095 (United States); Woods, Kaley; Boucher, Salime [RadiaBeam Technologies, Santa Monica, California 90404 (United States)

    2014-04-15

    Purpose: To investigate the feasibility of using intermediate energy 2 MV x-rays for extracranial robotic intensity modulated radiation therapy. Methods: Two megavolts flattening filter free x-rays were simulated using the Monte Carlo code MCNP (v4c). A convolution/superposition dose calculation program was tuned to match the Monte Carlo calculation. The modeled 2 MV x-rays and actual 6 MV flattened x-rays from existing Varian Linacs were used in integrated beam orientation and fluence optimization for a head and neck, a liver, a lung, and a partial breast treatment. A column generation algorithm was used for the intensity modulation and beam orientation optimization. Identical optimization parameters were applied in three different planning modes for each site: 2, 6 MV, and dual energy 2/6 MV. Results: Excellent agreement was observed between the convolution/superposition and the Monte Carlo calculated percent depth dose profiles. For the patient plans, overall, the 2/6 MV x-ray plans had the best dosimetry followed by 2 MV only and 6 MV only plans. Between the two single energy plans, the PTV coverage was equivalent but 2 MV x-rays improved organs-at-risk sparing. For the head and neck case, the 2MV plan reduced lips, mandible, tongue, oral cavity, brain, larynx, left and right parotid gland mean doses by 14%, 8%, 4%, 14%, 24%, 6%, 30% and 16%, respectively. For the liver case, the 2 MV plan reduced the liver and body mean doses by 17% and 18%, respectively. For the lung case, lung V20, V10, and V5 were reduced by 13%, 25%, and 30%, respectively. V10 of heart with 2 MV plan was reduced by 59%. For the partial breast treatment, the 2 MV plan reduced the mean dose to the ipsilateral and contralateral lungs by 27% and 47%, respectively. The mean body dose was reduced by 16%. Conclusions: The authors showed the feasibility of using flattening filter free 2 MV x-rays for extracranial treatments as evidenced by equivalent or superior dosimetry compared to 6 MV plans

  8. Measurements of yields of fission products in the reaction of {sup 238}U with high-energy p, d and n beams

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, J.A.; Ahmad, I.; Back, B.B. [and others

    1995-08-01

    An experiment was performed at the Michigan State University cyclotron to determine the yields of neutron-rich fission products in the reaction of {sup 238}U with 100-MeV neutrons, 200-MeV deuterons and 200-MeV protons. Several 1-mm-thick {sup 238}U foils were irradiated for 100-second intervals sequentially for each configuration and the ten spectra were added for higher statistics. The three successive spectra, each for a 40 s period, were accumulated for each sample. Ten foils were irradiated. Successive spectra allowed us to determine approximate half-lives of the gamma peaks. Several arrangements, which were similar to the setup we plan to use in our radioactive beam proposal, were used for the production of fission products. For the high-energy neutron irradiation, U foils were placed after a 5-inch-long, 1-inch-diameter Be cylinder which stopped the 200-MeV deuteron beam generating 100-MeV neutrons. Arrangements for deuteron irradiation included direct irradiation of U foils, placing U foils after different lengths of (0.5 inch, 1.0 inch and 1.5 inch) 2-inch diameter U cylinder. Since the deuteron range in uranium is 17 mm, some of the irradiations were due to the secondary neutrons from the deuteron-induced fission of U. Similar arrangements were also used for the 200-MeV proton irradiation of the {sup 238}U foils. In all cases, several neutron-rich fission products were identified and their yields determined. In particular, we were able to observe Sn in all the runs and determine its yield. The data show that with our proposed radioactive device we will be able to produce more than 10{sup 12} {sup 132}Sn atoms per second in the target. Assuming an overall efficiency of 1 %, we will be able to deliver one particle nanoampere of {sup 132}Sn beam at a target location. Detailed analysis of the {gamma}-ray spectra is in progress.

  9. SPIDER Progress Towards High Resolution Correlated Fission Product Data

    Science.gov (United States)

    Shields, Dan; Meierbachtol, Krista; Tovesson, Fredrik; Arnold, Charles; Blackeley, Rick; Bredeweg, Todd; Devlin, Matt; Hecht, Adam; Jandel, Marian; Jorgenson, Justin; Nelson, Ron; White, Morgan; Spider Team

    2014-09-01

    The SPIDER detector (SPectrometer for Ion DEtermination in fission Research) is under development with the goal of obtaining high-resolution, high-efficiency, correlated fission product data needed for many applications including the modeling of next generation nuclear reactors, stockpile stewardship, and the fundamental understanding of the fission process. SPIDER simultaneously measures velocity and energy of both fission products to calculate fission product yields (FPYs), neutron multiplicity (ν), and total kinetic energy (TKE). A detailed description of the prototype SPIDER detector components will be presented. Characterization measurements with alpha and spontaneous fission sources will also be discussed. LA-UR-14-24875. The SPIDER detector (SPectrometer for Ion DEtermination in fission Research) is under development with the goal of obtaining high-resolution, high-efficiency, correlated fission product data needed for many applications including the modeling of next generation nuclear reactors, stockpile stewardship, and the fundamental understanding of the fission process. SPIDER simultaneously measures velocity and energy of both fission products to calculate fission product yields (FPYs), neutron multiplicity (ν), and total kinetic energy (TKE). A detailed description of the prototype SPIDER detector components will be presented. Characterization measurements with alpha and spontaneous fission sources will also be discussed. LA-UR-14-24875. This work is in part supported by LANL Laboratory Directed Research and Development Projects 20110037DR and 20120077DR.

  10. Fission barrier heights in the A ∼ 200 mass region

    Indian Academy of Sciences (India)

    K Mahata

    2015-08-01

    Statistical model analysis is carried out for - and -induced fission reactions using a consistent description for fission barrier and level density in A ∼ 200 mass region. A continuous damping of shell correction with excitation energy is considered. Extracted fission barriers agree well with the recent microscopic–macroscopic model. The shell corrections at the saddle point were found to be insignificant.

  11. Mass Distribution Measurement of 252Cf Spontaneous Fission

    Institute of Scientific and Technical Information of China (English)

    LIU; Shi-long; YANG; Yi; ZHANG; Chun-li; HAN; Hong-yin

    2015-01-01

    The E-v method of measuring the kinetic energy(E)and velocity(v)of outgoing fission products has been utilized,with the goal of measuring the mass resolution better than 1atomic mass units(amu),and could identify every mass for light fission products of unsymmetrical fission.This work measured mass yield distribution

  12. Fusion-fission study at IUAC: Recent results

    Science.gov (United States)

    Pullanhiotan, Sugathan

    2016-10-01

    Several properties observed in heavy ion induced fission led to the conclusion that fission is not always originated from fully equilibrated compound nucleus. Soon after the collision of two nuclei, it forms a di-nuclear system than can fission before a compound nucleus is formed. This process termed quasi-fission is a major hurdle to the formation of heavier elements by fusion. Fission originated before complete equilibration showed anomalously large angular anisotropy and mass distribution wider than what is expected from compound nucleus fission. The standard statistical model fails to predict the outcome of quasi-fission and currently no dynamical model is fully developed to predict all the features of quasi-fission. Though much progress has been made in recent times, a full understanding of the fission dynamics is still missing. Experiments identifying the influence of entrance channel parameters on dynamics of fusion-fission showed contrasting results. At IUAC accelerator facility many experiments have been performed to make a systematic study of fission dynamics using mass distribution, angular distribution and neutron multiplicity measurements in mass region around A ∼ 200. Recent measurement on mass distribution of fission fragment from reaction 19 F +206,208 Pb around fusion barrier energy showed the influence of multi-mode fission in enhancing the mass variance at low excitation energy. In this talk I will present some of these results.

  13. Fission dynamics within time-dependent Hartree-Fock: boost-induced fission

    CERN Document Server

    Goddard, P M; Rios, A

    2015-01-01

    Background: Nuclear fission is a complex large-amplitude collective decay mode in heavy nuclei. Microscopic density functional studies of fission have previously concentrated on adiabatic approaches based on constrained static calculations ignoring dynamical excitations of the fissioning nucleus, and the daughter products. Purpose: To explore the ability of dynamic mean-field methods to describe induced fission processes, using quadrupole boosts in the nuclide $^{240}$Pu as an example. Methods: Quadrupole constrained Hartree-Fock calculations are used to create a potential energy surface. An isomeric state and a state beyond the second barrier peak are excited by means of instantaneous as well as temporally extended gauge boosts with quadrupole shapes. The subsequent deexcitation is studied in a time-dependent Hartree-Fock simulation, with emphasis on fissioned final states. The corresponding fission fragment mass numbers are studied. Results: In general, the energy deposited by the quadrupole boost is quickl...

  14. Critical validity assessment of theoretical models: charge-exchange at intermediate and high energies

    Science.gov (United States)

    Belkić, Dževad

    1999-06-01

    Exact comprehensive computations are carried out by means of four leading second-order approximations yielding differential cross sections dQ/ dΩ for the basic charge exchange process H ++H(1s)→H(1s)+H + at intermediate and high energies. The obtained extensive set of results is thoroughly tested against all the existing experimental data with the purpose of critically assessing the validity of the boundary corrected second-Born (CB2), continuum-distorted wave (CDW), impulse approximation (IA) and the reformulated impulse approximation (RIA). The conclusion which emerges from this comparative study clearly indicates that the RIA agrees most favorably with the measurements available over a large energy range 25 keV-5 MeV. Such a finding reaffirms the few-particle quantum scattering theory which imposes several strict conditions on adequate second-order methods. These requirements satisfied by the RIA are: (i) normalisations of all the scattering wave functions, (ii) correct boundary conditions in both entrance and exit channels, (iii) introduction of a mathematically justified two-center continuum state for the sum of an attractive and a repulsive Coulomb potential with the same interaction strength, (iv) inclusion of the multiple scattering effects neglected in the IA, (v) a proper description of the Thomas double scattering in good agreement with the experiments and without any unobserved peak splittings. Nevertheless, the performed comparative analysis of the above four approximations indicates that none of the methods is free from some basic shortcomings. Despite its success, the RIA remains essentially a high-energy model like the other three methods under study. More importantly, their perturbative character leaves virtually no room for further systematic improvements, since the neglected higher-order terms are prohibitively tedious for practical purposes and have never been computed exactly. To bridge this gap, we presently introduce the variational Pad

  15. Overview of research by the fission group in Trombay

    Indian Academy of Sciences (India)

    R K Chourdhury

    2015-08-01

    Nuclear fission studies in Trombay began nearly six decades ago, with the commissioning of the APSARA research reactor. Early experimental work was based on mass, kinetic energy distributions, neutron and X-ray emission in thermal neutron fission of 235U, which were carried out with indigenously developed detectors and electronics instrumentation. With the commissioning of CIRUS reactor and the availability of higher neutron flux, advanced experiments were carried out on ternary fission, pre-scission neutron emission, fragment charge distributions, quarternary fission, etc. In the late eighties, heavy-ion beams from the pelletron-based medium energy heavy-ion accelerator were available, which provided a rich variety of possibilities in nuclear fission studies. Pioneering work on fragment angular distributions, fission time-scales, transfer-induced fission, -ray multiplicities and mass–energy correlations were carried out, providing important information on the dynamics of the fission process. More recently, work on fission fragment -ray spectroscopy has been initiated, to understand the nuclear structure aspects of the neutron-rich fission fragment nuclei. There have also been parallel efforts to carry out theoretical studies in the areas of shell effects, superheavy nuclei, fusion–fission dynamics, fragment angular distributions, etc. to complement the experimental studies. This paper will provide a glimpse of the work carried out by the fission group at Trombay in the above-mentioned topics.

  16. Application of the dinuclear system model to fission process

    Directory of Open Access Journals (Sweden)

    Andreev A. V.

    2016-01-01

    Full Text Available A theoretical evaluation of the collective excitation spectra of nucleus at large deformations is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two-cluster configurations in a dynamical way, permitting exchange of nucleons between clusters. In this work the method of calculation of the potential energy and the collective spectrum of fissioning nucleus at scission point is presented. Combining the DNS model calculations and the statistical model of fission we calculate the mass, total kinetic energy, and angular distribution of fission fragments for the neutron–induced fission of 239Pu.

  17. Ternary fission of (_

    Directory of Open Access Journals (Sweden)

    Dariush Naderi

    2017-05-01

    Full Text Available Using three cluster model, the ternary fission of (_"98" ^"252" Cf is studied. We applied collinear and equatorial configurations to study the ternary fission of (_"98" ^"252" Cf when three fragments are Sn, Ni and Ca. The potential energy of collinear and equatorial configurations is calculated. We calculated the potential energy for odd and even values of A3. Also, we compared the potential energy for (_"50" ^(A_"1" Sn+(_"28" ^(A_"2" Ni+(_"20" ^(A_"3" Ca and (_"50" ^(A_"1" -"1" Sn+(_"28" ^(A_"2" +"1" Ni+(_"20" ^(A_"3" Ca to investigate the influence of neutron numbers of three fragments. Obtained results show that for (_"50" ^(A_"1" Sn+(_"28" ^(A_"2" Ni+(_"20" ^(A_"3" Ca reaction with even A3 in collinear and equatorial configurations, the potential energy and penetration probability have ,respectively, minimum and maximum values in A3=48 whereas for odd values of A3 the minimum value for the potential energy and the maximum value of penetration probability take place in A3=49. For (_"50" ^(A_"1" -"1" Sn+(_"28" ^(A_"2" +"1" Ni+(_"20" ^(A_"3" Ca reactions in collinear and equatorial cases, the minimum value of potential energy and maximum value of penetration probability take place in A3=49 and A3=50, respectively, for even and odd values of A3. Also, among all the possible reactions the lowest value of potential energy and highest value of penetration probability happen for (_"50" ^132Sn+(_"28" ^72Ni+(_"20" ^48Ca configuration.

  18. Isotopic fission fragment distributions as a deep probe to fusion-fission dynamics

    CERN Document Server

    Farget, F; Delaune, O; Tarasov, O B; Derkx, X; Schmidt, K -H; Amthor, A M; Audouin, L; Bacri, C -O; Barreau, G; Bastin, B; Bazin, D; Blank, B; Benlliure, J; Caceres, L; Casarejos, E; Chibihi, A; Fernandez-Dominguez, B; Gaudefroy, L; Golabek, C; Grevy, S; Jurado, B; Kamalou, O; Lemasson, A; Lukyanov, S; Mittig, W; Morrissey, D J; Navin, A; Pereira, J; Perrot, L; Rejmund, M; Roger, T; Saint-Laurent, M -G; Savajols, H; Schmitt, C; Sherill, B M; Stodel, C; Taieb, J; Thomas, J -C; Villari, A C

    2012-01-01

    During the fission process, the nucleus deforms and elongates up to the two fragments inception and their final separation at scission deformation. The evolution of the nucleus energy with deformation is determined by the macroscopic properties of the nucleus, and is also strongly influenced by the single-particle structure of the nucleus. The fission fragment distribution is a direct consequence of the deformation path the nucleus has encountered, and therefore is the most genuine experimental observation of the potential energy landscape of the deforming nucleus. Very asymmetric fusion-fission reactions at energy close to the Coulomb barrier, produce well-defined conditions of the compound nucleus formation, where processes such as quasi-fission, pre-equilibrium emission and incomplete fusion are negligible. In the same time, the excitation energy is sufficient to reduce significantly structural effects, and mostly the macroscopic part of the potential is responsible for the formation of the fission fragmen...

  19. Search for Singlet Fission Chromophores

    Energy Technology Data Exchange (ETDEWEB)

    Havlas, Z.; Akdag, A.; Smith, M. B.; Dron, P.; Johnson, J. C.; Nozik, A. J.; Michl, J.

    2012-01-01

    Singlet fission, in which a singlet excited chromophore shares its energy with a ground-state neighbor and both end up in their triplet states, is of potential interest for solar cells. Only a handful of compounds, mostly alternant hydrocarbons, are known to perform efficiently. In view of the large number of conditions that a successful candidate for a practical cell has to meet, it appears desirable to extend the present list of high performers to additional classes of compounds. We have (i) identified design rules for new singlet fission chromophores and for their coupling to covalent dimers, (ii) synthesized them, and (iii) evaluated their performance as neat solids or covalent dimers.

  20. Thorium-uranium fission radiography

    Science.gov (United States)

    Haines, E. L.; Weiss, J. R.; Burnett, D. S.; Woolum, D. S.

    1976-01-01

    Results are described for studies designed to develop routine methods for in-situ measurement of the abundance of Th and U on a microscale in heterogeneous samples, especially rocks, using the secondary high-energy neutron flux developed when the 650 MeV proton beam of an accelerator is stopped in a 42 x 42 cm diam Cu cylinder. Irradiations were performed at three different locations in a rabbit tube in the beam stop area, and thick metal foils of Bi, Th, and natural U as well as polished silicate glasses of known U and Th contents were used as targets and were placed in contact with mica which served as a fission track detector. In many cases both bare and Cd-covered detectors were exposed. The exposed mica samples were etched in 48% HF and the fission tracks counted by conventional transmitted light microscopy. Relative fission cross sections are examined, along with absolute Th track production rates, interaction tracks, and a comparison of measured and calculated fission rates. The practicality of fast neutron radiography revealed by experiments to data is discussed primarily for Th/U measurements, and mixtures of other fissionable nuclei are briefly considered.

  1. Determination of the fission-neutron averaged cross sections of some high-energy threshold reactions of interest for reactor dosimetry

    CERN Document Server

    Arribere, M A; Ribeiro-Guevara, S; Korochinsky, S; Blostein, J J

    2003-01-01

    For three high threshold reactions, we have measured the cross sections averaged over a sup 2 sup 3 sup 5 U fission neutron spectrum. The measured reactions, and corresponding averaged cross sections found, are: sup 1 sup 2 sup 7 I(n,2n) sup 1 sup 2 sup 6 I, (1.36+-0.12) mb; sup 9 sup 0 Zr(n,2n) sup 8 sup 9 sup m Zr, (13.86+-0.83) mu b; and sup 5 sup 8 Ni(n,d+np+pn) sup 5 sup 7 Co, (274+-15) mu b; all referred to the well known standard of (111+-3) mb for the sup 5 sup 8 Ni(n,p) sup 5 sup 8 sup m sup + sup g Co averaged cross section. The measured cross sections are of interest in nuclear engineering for the characterization of the fast neutron component in the energy distribution of reactor neutrons. (author)

  2. Ternary fission of superheavy elements

    Science.gov (United States)

    Balasubramaniam, M.; Vijayaraghavan, K. R.; Manimaran, K.

    2016-01-01

    Ternary fission of superheavy nuclei is studied within the three-cluster model potential energy surfaces (PESs). Due to shell effects, the stability of superheavy nuclei has been predicted to be associated with Z =114 , 120, and 126 for protons and N =184 for neutrons. Taking some representative nuclei we have extended the ternary fission studies to superheavy nuclei. We adopted two minimization procedures to minimize the potential and considered different arrangements of the fragments. The PES from one-dimensional minimization reveals a strong cluster region favoring various ternary breakups for an arrangement in which the lightest fragment is kept at the center. The PES obtained from two-dimensional minimization reveals strong preference of ternary fragmentation in the true ternary fission region. Though the dominant decay mode of superheavy nuclei is α decay, the α -accompanied ternary breakup is found to be a nonfavorable one. Further, the prominent ternary combinations are found to be associated with the neutron magic number.

  3. Investigation of the fission fragment properties of the reaction sup 2 sup 3 sup 8 U(n,f) at incident neutron energies up to 5.8 MeV

    CERN Document Server

    Vivès, F; Bax, H; Oberstedt, S

    2000-01-01

    The fission fragment properties of the reaction sup 2 sup 3 sup 8 U(n,f) have been studied, at different incident neutron energies ranging from E sub n =1.2 to 5.8 MeV. The pre-neutron emission mass, kinetic energy and fission fragment angular distributions have been investigated with a double Frisch-gridded ionization chamber. The influence of the subthreshold vibrational resonances and of the proton pairing effect on the fission fragment properties is clearly visible. The total kinetic energy averaged over all fission fragment masses TKEbar shows an increasing trend up to E sub n =3.5 MeV with a sudden drop at roughly E sub n =3.8 MeV which has been attributed to the onset of pair breaking at the barrier. Above E sub n =3.8 MeV, the TKEbar is again continuously increasing. The changes in the mass yield and TKEbar(A) distributions have been studied as a function of the compound nuclear excitation energy and their contribution to the observed variations in the TKEbar have been determined. The two-dimensional ...

  4. Fission Dynamics: The Quest of a Temperature Dependent Nuclear Viscosity

    Directory of Open Access Journals (Sweden)

    E. Vardaci

    2013-08-01

    Full Text Available This paper presents a journey within some open questions about the current use of a temperature dependent nuclear viscosity in models of nuclear fission and proposes an alternative experimental approach by using systems of intermediate fissility. This study is particularly relevant because: i systems of intermediate fissility offer a suitable frame-work since the intervals between the compound nucleus and scission point temperatures with increasing excitation energy are much smaller than in the case of heavier systems, ii the dependence of viscosity on the temperature may change with the fissility of the composite system; iii the opportunity to measure also observables in the evaporation residues channel translates into a larger set of effective constraints for the models.

  5. Theoretical Description of the Fission Process

    Energy Technology Data Exchange (ETDEWEB)

    Witold Nazarewicz

    2009-10-25

    Advanced theoretical methods and high-performance computers may finally unlock the secrets of nuclear fission, a fundamental nuclear decay that is of great relevance to society. In this work, we studied the phenomenon of spontaneous fission using the symmetry-unrestricted nuclear density functional theory (DFT). Our results show that many observed properties of fissioning nuclei can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. From the calculated collective potential and collective mass, we estimated spontaneous fission half-lives, and good agreement with experimental data was found. We also predicted a new phenomenon of trimodal spontaneous fission for some transfermium isotopes. Our calculations demonstrate that fission barriers of excited superheavy nuclei vary rapidly with particle number, pointing to the importance of shell effects even at large excitation energies. The results are consistent with recent experiments where superheavy elements were created by bombarding an actinide target with 48-calcium; yet even at high excitation energies, sizable fission barriers remained. Not only does this reveal clues about the conditions for creating new elements, it also provides a wider context for understanding other types of fission. Understanding of the fission process is crucial for many areas of science and technology. Fission governs existence of many transuranium elements, including the predicted long-lived superheavy species. In nuclear astrophysics, fission influences the formation of heavy elements on the final stages of the r-process in a very high neutron density environment. Fission applications are numerous. Improved understanding of the fission process will enable scientists to enhance the safety and reliability of the nation’s nuclear stockpile and nuclear reactors. The deployment of a fleet of safe and efficient advanced reactors, which will also minimize radiotoxic

  6. Superfluid dynamics of 258Fm fission

    CERN Document Server

    Scamps, Guillaume; Lacroix, Denis

    2015-01-01

    Theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The slow, mostly adiabatic motion through the fission barrier is followed by a fast, non-adiabatic descent of the potential between the fragments. The latter stage is essentially unexplored. However, it is crucial as it generates most of the excitation energy in the fragments. The superfluid dynamics in the latter stage of fission is obtained with the time-dependent Hartree-Fock theory including BCS dynamical pairing correlations. The fission modes of the 258Fm nucleus are studied. The resulting fission fragment characteristics show a good agreement with experimental data. Quantum shell effects are shown to play a crucial role in the dynamics and formation of the fragments. The importance of quantum fluctuations beyond the independent particle/quasi-particle picture is underlined and qualitatively studied.

  7. Charge Dependence and Electric Quadrupole Effects on Single-Nucleon Removal in Relativistic and Intermediate Energy Nuclear Collisions

    Science.gov (United States)

    Norbury, John W.

    1992-01-01

    Single nucleon removal in relativistic and intermediate energy nucleus-nucleus collisions is studied using a generalization of Weizsacker-Williams theory that treats each electromagnetic multipole separately. Calculations are presented for electric dipole and quadrupole excitations and incorporate a realistic minimum impact parameter, Coulomb recoil corrections, and the uncertainties in the input photonuclear data. Discrepancies are discussed. The maximum quadrupole effect to be observed in future experiments is estimated and also an analysis of the charge dependence of the electromagnetic cross sections down to energies as low as 100 MeV/nucleon is made.

  8. Development of Si-based detectors for intermediate energy heavy-ion physics at a storage-ring accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Whitlow, H.J.; Jaworowski, J.; Leandersson, M.; El Bouanani, M. [Lund Institute of Technology, Solvegatan Lund, (Sweden). Department of Nuclear Physics; Jakobsson, B. [Lund Univ. (Sweden). Dept. of Cosmic and Subatomic Physics; Romanski, J.; Westerberg, L.; Van Veldhuizen, E.J. [Uppsala Univ. (Sweden); The Chicsi Collaboration

    1996-12-31

    Ultrahigh vacuum (UHV) compatible Si detectors are being developed by the CELSIUS Heavy lon Collaboration (CHIC) for measuring the energy and identity of Intermediate Mass Fragments (IMF) with Z {approx} 3 - 12 and energies of 0.7 - I 0 A MeV. Here we give an overview of the development of Si {delta}E-E detector telescopes and investigations on IMF identification based on the pulse shape from Si-detectors where the particles impinge on the rear-face of the detector. 9 refs., 4 figs.

  9. Charge Dependence and Electric Quadrupole Effects on Single-Nucleon Removal in Relativistic and Intermediate Energy Nuclear Collisions

    Science.gov (United States)

    Norbury, John W.

    1992-01-01

    Single nucleon removal in relativistic and intermediate energy nucleus-nucleus collisions is studied using a generalization of Weizsacker-Williams theory that treats each electromagnetic multipole separately. Calculations are presented for electric dipole and quadrupole excitations and incorporate a realistic minimum impact parameter, Coulomb recoil corrections, and the uncertainties in the input photonuclear data. Discrepancies are discussed. The maximum quadrupole effect to be observed in future experiments is estimated and also an analysis of the charge dependence of the electromagnetic cross sections down to energies as low as 100 MeV/nucleon is made.

  10. Dynamics of light, intermediate, heavy and superheavy nuclear systems formed in heavy-ion collisions

    Indian Academy of Sciences (India)

    Manoj K Sharma; Gurvinder Kaur

    2014-05-01

    The dynamical description of light, intermediate, heavy and superheavy nuclei formed in heavy-ion collisions is worked out using the dynamical cluster decay model (DCM), with reference to various effects such as deformation and orientation, temperature, angular momentum etc. Based on the quantum mechanical fragmentation theory (QMFT), DCM has been applied to understand the decay mechanism of a large number of nuclei formed in low-energy heavy-ion reactions. Various features related to the dynamics of competing decay modes of nuclear systems are explored by addressing the experimental data of a number of reactions in light, intermediate, heavy and superheavy mass regions. The DCM, being a non-statistical description for the decay of a compound nucleus, treats light particles (LPs) or equivalently evaporation residues (ERs), intermediate mass fragments (IMFs) and fission fragments on equal footing and hence, provides an alternative to the available statistical model approaches to address fusion–fission and related phenomena.

  11. A revised calculational model for fission

    Energy Technology Data Exchange (ETDEWEB)

    Atchison, F.

    1998-09-01

    A semi-empirical parametrization has been developed to calculate the fission contribution to evaporative de-excitation of nuclei with a very wide range of charge, mass and excitation-energy and also the nuclear states of the scission products. The calculational model reproduces measured values (cross-sections, mass distributions, etc.) for a wide range of fissioning systems: Nuclei from Ta to Cf, interactions involving nucleons up to medium energy and light ions. (author)

  12. Dual-fission chamber and neutron beam characterization for fission product yield measurements using monoenergetic neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, C.; Fallin, B. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Gooden, M.E., E-mail: megooden@tunl.duke.edu [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Department of Physics, North Carolina State University, Raleigh, NC 27605 (United States); Howell, C.R. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Kelley, J.H. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Department of Physics, North Carolina State University, Raleigh, NC 27605 (United States); Tornow, W. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Arnold, C.W.; Bond, E.M.; Bredeweg, T.A.; Fowler, M.M.; Moody, W.A.; Rundberg, R.S.; Rusev, G.; Vieira, D.J.; Wilhelmy, J.B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Becker, J.A.; Macri, R.; Ryan, C.; Sheets, S.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); and others

    2014-09-01

    A program has been initiated to measure the energy dependence of selected high-yield fission products used in the analysis of nuclear test data. We present out initial work of neutron activation using a dual-fission chamber with quasi-monoenergetic neutrons and gamma-counting method. Quasi-monoenergetic neutrons of energies from 0.5 to 15 MeV using the TUNL 10 MV FM tandem to provide high-precision and self-consistent measurements of fission product yields (FPY). The final FPY results will be coupled with theoretical analysis to provide a more fundamental understanding of the fission process. To accomplish this goal, we have developed and tested a set of dual-fission ionization chambers to provide an accurate determination of the number of fissions occurring in a thick target located in the middle plane of the chamber assembly. Details of the fission chamber and its performance are presented along with neutron beam production and characterization. Also presented are studies on the background issues associated with room-return and off-energy neutron production. We show that the off-energy neutron contribution can be significant, but correctable, while room-return neutron background levels contribute less than <1% to the fission signal.

  13. Design and construction of a spectrometer facility and experiment for intermediate energy proton scattering on helium. [Wave functions, preliminary experimental techniques

    Energy Technology Data Exchange (ETDEWEB)

    Rolfe, R.M.

    1976-12-01

    The goal of the research was to investigate proton scattering on nuclei at intermediate energies and in particular to investigate proton scattering on helium. A theoretical investigation of the helium nucleus and the nature of the intermediate energy interaction, design and optimization of an energy-loss spectrometer facility for proton-nucleus scattering, and the unique superfluid helium target and experimental design are discussed.

  14. SP-FISPACT2001. A computer code for activation and decay calculations for intermediate energies. A connection of FISPACT with MCNPX; SP-FISPACT2001. Una connessione di FISPACT con MCNPX per la codifica computerizzata delle energie intermedie

    Energy Technology Data Exchange (ETDEWEB)

    Petrovich, C. [ENEA, Divisione Sistemi Energetici Ecosostenibili, Centro Ricerche Ezio Clementel, Bologna (Italy)

    2001-07-01

    The calculation of the number of atoms and the activity of materials following nuclear interactions at incident energies up to several GeV is necessary in the design of Accelerator Driven Systems, Radioactive Ion Beam and proton accelerator facilities such as spallation neutron sources. As well as the radioactivity of the materials, this allows the evaluation of the formation of active gaseous elements and the assessment of possible corrosion problems The particle energies involved here are higher than those used in typical nuclear reactors and fusion devices for which many codes already exist. These calculations can be performed by coupling two different computer codes: MCNPX and SP-FISPACT. MCNPX performs Monte Carlo particle transport up to energies of several GeV. SP-FISPACT is a modification of FISPACT, a code designed for fusion applications and able to calculate neutron activation for energies <20 MeV. In such a way it is possible to perform a hybrid calculation in which neutron activation data are used for neutron interactions at energies <20 MeV and intermediate energy physics models for all the other nuclear interactions. [Italian] In fase di design di sistemi ADS (Accelerator Driven Systems), di strutture con acceleratori quali quelli finalizzate alla produzione di fasci di ioni radioattivi o a sorgenti neutroniche di spallazione e' necessario calcolare la composizione e l'attivita' di materiali a seguito di interazioni nucleari con energie fino a qualche GeV. Oltre la radioattivita' dei materiali, questi calcoli permettono di prevedere la formazione di elementi gassosi attivi e possibili problemi di corrosione. Le energie delle particelle qui coinvolte sono piu' alte di quelle usate in tipici reattori nucleari ed in dispositivi finalizzati alla fusione, per i quali sono gia' disponibili diversi codici. Questi tipi di calcoli possono essere eseguiti accoppiando due codici differenti: MCNPX e SP-FISPACT. MCNPX trasporta

  15. Spontaneous fission of the heaviest elements

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.C.

    1989-04-01

    Although spontaneous fission was discovered in /sup 238/U in 1940, detailed studies of the process were first made possible in the 1960's with the availability of milligram quantities of /sup 252/Cf. The advent of solid-state detectors made it possible to perform measurements of coincident fission fragments from even very short-lived spontaneous fission activities or those available in only very small quantities. Until 1971 it was believed that the main features of the mass and kinetic-energy distributions were essentially the same as those for thermal neutron-induced fission and that all low-energy fission proceeded via asymmetric mass division with total kinetic energies which could be derived by linear extrapolation from those of lighter elements. In 1971, measurements of /sup 257/Fm showed an increase in symmetric mass division with anomalously high TKE's. Subsequent experiments showed that in /sup 258/Fm and /sup 259/Fm, the most probable mass split was symmetric with very high total kinetic energy. Measurements for the heavier elements have shown symmetric mass distributions with both high and low total kinetic energies. Recent results for spontaneous fission properties of the heaviest elements are reviewed and compared with theory. 31 refs., 8 figs., 1 tab.

  16. Calculation of Prompt Fission Neutron Spectrum for 233U(n, f) Reaction by Semi-empirical Method

    Institute of Scientific and Technical Information of China (English)

    CHEN; Yong-jing; LIU; Ting-jin; SHU; Neng-chuan

    2013-01-01

    The prompt fission neutron spectra for neutron-induced fission of 233U for low energy neutron(below 6 MeV)are calculated using the nuclear evaporation theory with a semi-empirical method,in which the partition of the total excitation energy between the fission fragments for the nth+233U fission

  17. Degree of Rate Control: How Much the Energies of Intermediates and Transition States Control Rates

    DEFF Research Database (Denmark)

    Stegelmann, Carsten; Andreasen, Anders; Campbell, Charles T.

    2009-01-01

    For many decades, the concept of a “rate-determining step” has been of central importance in understanding chemical kinetics in multistep reaction mechanisms and using that understanding to advantage. Yet a rigorous method for identifying the rate-determining step in a reaction mechanism was only...... model for any reaction mechanism. Thus, it is very important to identify these rate-controlling transition states and rate-controlling intermediates for both applied and basic research. Here, we present a method for doing that....

  18. Fission cross section measurements for minor actinides

    Energy Technology Data Exchange (ETDEWEB)

    Fursov, B. [IPPE, Obninsk (Russian Federation)

    1997-03-01

    The main task of this work is the measurement of fast neutron induced fission cross section for minor actinides of {sup 238}Pu, {sup 242m}Am, {sup 243,244,245,246,247,248}Cm. The task of the work is to increase the accuracy of data in MeV energy region. Basic experimental method, fissile samples, fission detectors and electronics, track detectors, alpha counting, neutron generation, fission rate measurement, corrections to the data and error analysis are presented in this paper. (author)

  19. Rearrangement of cluster structure during fission processes

    DEFF Research Database (Denmark)

    Lyalin, Andrey G.; Obolensky, Oleg I.; Solov'yov, Andrey V.

    2004-01-01

    Results of molecular dynamics simulations of fission reactions $Na_10^2+ -->Na_7^++ Na_3^+ and Na_18^2+--> 2Na_9^+ are presented. The dependence of the fission barriers on the isomer structure of the parent cluster is analysed. It is demonstrated that the energy necessary for removing homothetic...... groups of atoms from the parent cluster is largely independent of the isomer form of the parent cluster. The importance of rearrangement of the cluster structure during the fission process is elucidated. This rearrangement may include transition to another isomer state of the parent cluster before actual...

  20. Fission cross section measurements for minor actinides

    Energy Technology Data Exchange (ETDEWEB)

    Fursov, B. [IPPE, Obninsk (Russian Federation)

    1997-03-01

    The main task of this work is the measurement of fast neutron induced fission cross section for minor actinides of {sup 238}Pu, {sup 242m}Am, {sup 243,244,245,246,247,248}Cm. The task of the work is to increase the accuracy of data in MeV energy region. Basic experimental method, fissile samples, fission detectors and electronics, track detectors, alpha counting, neutron generation, fission rate measurement, corrections to the data and error analysis are presented in this paper. (author)

  1. Fission fragment mass distributions in reactions populating 200Pb

    CERN Document Server

    Chaudhuri, A; Ghosh, T K; Banerjee, K; Sadhukhan, Jhilam; Bhattacharya, S; Roy, P; Roy, T; Bhattacharya, C; Asgar, Md A; Dey, A; Kundu, S; Manna, S; Meena, J K; Mukherjee, G; Pandey, R; Rana, T K; Srivastava, V; Dubey, R; Kaur, Gurpreet; Saneesh, N; Sugathan, P; Bhattacharya, P

    2016-01-01

    The fission fragment mass distributions have been measured in the reactions 16O + 184W and 19F+ 181Ta populating the same compound nucleus 200Pb? at similar excitation energies. It is found that the widths of the mass distribution increases monotonically with excitation energy, indicating the absence of quasi-fission for both reactions. This is contrary to two recent claims of the presence of quasi-fission in the above mentioned reactions.

  2. An Isoratio Method to Study Free Energy and Temperature Effects in Intermediate Mass Fragments Produced in Heavy-Ion Collisions

    Science.gov (United States)

    Ma, Chun-Wang; Qiao, Chun-Yuan; Ding, Tian-Tian; Niu, Fei; Song, Yi-Dan; Niu, Yi-Fei

    2016-07-01

    An isoratio method, i.e., the isotopic (isotonic) ratio among three isotopes (isotones), is proposed to study the free energy and temperature effects in the intermediate mass fragments produced in heavy-ion collisions. The parameterizations for the free energy of nucleus at low temperature, which have been proposed in the framework of the density functional theory using the SKM skymre interaction, are adopted to calculate the temperature-dependent free energy of fragment. By analyzing the measured yields of fragments in the 140A MeV 58,64Ni + 9Be reactions, it is verified that the free energy in the isoratio is almost the same for different reactions. A temperature-dependent pairing-energy is introduced into the parameterizations for free energy, which reveals that the weakened pairing energy at the low temperature accounts for the weakened or disappearing odd-even staggering in isoratio. Supported by the Program for Science and Technology Innovation Talents in Universities of Henan Province under Grant No. 13HASTIT046, the Creative Experimental Project of National Undergraduate Students (CEPNU201510476017)

  3. Isospin effects of the Skyrme potential and the momentum dependent interaction at intermediate energy heavy ion collisions

    Institute of Scientific and Technical Information of China (English)

    GUO Wen-Jun; LIU Jian-Ye

    2008-01-01

    We improve the isospin dependent quantum molecular dynamical model by including isospin effects in the Skyrme potential and the momentum dependent interaction to obtain an isospin dependent Skyrme potential and an isospin dependent momentum interaction. We investigate the isospin effects of Skyrme potential and momentum dependent interaction on the isospin fractionation ratio and the dynamical mechanism in intermediate energy heavy ion collisions. It is found that the isospin dependent Skyrme potential and the isospin dependent momentum interaction produce some important isospin effects in the isospin fractionation ratio.

  4. Intermediate-energy inverse-kinematics one-proton pickup reactions on neutron-deficient $fp$-shell nuclei

    CERN Document Server

    McDaniel, S; Tostevin, J A; Baugher, T; Bazin, D; Brown, B A; Cook, J M; Glasmacher, T; Grinyer, G F; Ratkiewicz, A; Weisshaar, D

    2012-01-01

    Background: Thick-target-induced nucleon-adding transfer reactions onto energetic rare-isotope beams are an emerging spectroscopic tool. Their sensitivity to single-particle structure complements one-nucleon removal reaction capabilities in the quest to reveal the evolution of nuclear shell structure in very exotic nuclei. Purpose: To add intermediate-energy, carbon-target-induced one-proton pickup reactions to the arsenal of $\\gamma$-ray tagged direct reactions applicable in the regime of low beam intensities and to apply these for the first time to $fp$-shell nuclei. Methods: Inclusive and partial cross sections were measured for the $\

  5. Double-electron detachment cross sections in intermediate-energy H{sup {minus}} plus noble-gas collisions

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J.S.; Fang, X.D.; Sen, A.; Matulioniene, R.; Kvale, T.J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States)

    1995-07-01

    Absolute measurements of the total double-electron detachment (DED) cross sections for 3- to 50-keV H{sup {minus}} ions incident on helium atoms and for 5- to 50-keV H{sup {minus}} ions incident on neon and argon atoms are reported in this paper. The present DED cross sections are in better agreement with the previously reported DED cross sections for helium targets than for either neon or argon targets. A semiempirical calculation of the double detachment cross sections for the intermediate-energy collision region is also presented in this paper.

  6. Impact parameter and beam energy dependence for azimuthal asymmetry of direct photons and free protons in intermediate energy heavy-ion collisions

    Institute of Scientific and Technical Information of China (English)

    LIU Gui-Hua; MA Yu-Gang; CAI Xiang-Zhou; FANG De-Qing; SHEN Wen-Qing; TIAN Wen-Dong; WANG Kun

    2009-01-01

    Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we have calculated the impact parameter and beam energy dependence for azimuthal asymmetry, characterized by directed transverse flow parameter F and elliptic asymmetry coefficient v2, of direct photons and the corresponding free protons in intermediate energy heavy-ion collisions. It is further shown the anti-correlated azimuthal asymmetry between direct photons and free protons.

  7. A brief review of intermediate controlled nuclear syntheses (ICNS) without harmful radiations

    Energy Technology Data Exchange (ETDEWEB)

    Lanjewar, R. B. [Department of Chemistry Dharampeth M. P. Deo Memorial Science College, NAGPUR-440033, India rb-lanjewar@rediffmail.com (India)

    2015-03-10

    Hadronic mechanics gave birth to new magnecular fuels. The present day demand is of clean energy source that is cheap and abundant. Clean energy can be obtained by harnessing renewable energy sources like solar, wind etc. Nuclear energy conventionally produced by fission reactions emits hazardous radiation and radioactive waste. The requirements of clean and safe energy gets fulfilled by novel fuel that achieved by elevating the traditional quantum mechanics to hadronic mechanics and to hadronic chemistry. In the present paper, a comprehensive review on both the theoretical and experimental aspect of the Intermediate Controlled Nuclear Synthesis (ICNS) as developed by Italian American Scientist Professor R. M. Santilli.

  8. The VERDI fission fragment spectrometer

    Science.gov (United States)

    Frégeau, M. O.; Bryś, T.; Gamboni, Th.; Geerts, W.; Oberstedt, S.; Oberstedt, A.; Borcea, R.

    2013-12-01

    The VERDI time-of-flight spectrometer is dedicated to measurements of fission product yields and of prompt neutron emission data. Pre-neutron fission-fragment masses will be determined by the double time-of-flight (TOF) technique. For this purpose an excellent time resolution is required. The time of flight of the fragments will be measured by electrostatic mirrors located near the target and the time signal coming from silicon detectors located at 50 cm on both sides of the target. This configuration, where the stop detector will provide us simultaneously with the kinetic energy of the fragment and timing information, significantly limits energy straggling in comparison to legacy experimental setup where a thin foil was usually used as a stop detector. In order to improve timing resolution, neutron transmutation doped silicon will be used. The high resistivity homogeneity of this material should significantly improve resolution in comparison to standard silicon detectors. Post-neutron fission fragment masses are obtained form the time-of-flight and the energy signal in the silicon detector. As an intermediary step a diamond detector will also be used as start detector located very close to the target. Previous tests have shown that poly-crystalline chemical vapour deposition (pCVD) diamonds provides a coincidence time resolution of 150 ps not allowing complete separation between very low-energy fission fragments, alpha particles and noise. New results from using artificial single-crystal diamonds (sCVD) show similar time resolution as from pCVD diamonds but also sufficiently good energy resolution.

  9. The VERDI fission fragment spectrometer

    Directory of Open Access Journals (Sweden)

    Frégeau M.O.

    2013-12-01

    Full Text Available The VERDI time-of-flight spectrometer is dedicated to measurements of fission product yields and of prompt neutron emission data. Pre-neutron fission-fragment masses will be determined by the double time-of-flight (TOF technique. For this purpose an excellent time resolution is required. The time of flight of the fragments will be measured by electrostatic mirrors located near the target and the time signal coming from silicon detectors located at 50 cm on both sides of the target. This configuration, where the stop detector will provide us simultaneously with the kinetic energy of the fragment and timing information, significantly limits energy straggling in comparison to legacy experimental setup where a thin foil was usually used as a stop detector. In order to improve timing resolution, neutron transmutation doped silicon will be used. The high resistivity homogeneity of this material should significantly improve resolution in comparison to standard silicon detectors. Post-neutron fission fragment masses are obtained form the time-of-flight and the energy signal in the silicon detector. As an intermediary step a diamond detector will also be used as start detector located very close to the target. Previous tests have shown that poly-crystalline chemical vapour deposition (pCVD diamonds provides a coincidence time resolution of 150 ps not allowing complete separation between very low-energy fission fragments, alpha particles and noise. New results from using artificial single-crystal diamonds (sCVD show similar time resolution as from pCVD diamonds but also sufficiently good energy resolution.

  10. A fission fragment detector for correlated fission output studies

    Energy Technology Data Exchange (ETDEWEB)

    Mosby, S., E-mail: smosby@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tovesson, F.; Couture, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Duke, D.L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States); Kleinrath, V. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Idaho State University, Pocatello, ID 83201 (United States); Meharchand, R.; Meierbachtol, K.; O' Donnell, J.M.; Perdue, B.; Richman, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Shields, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States)

    2014-09-01

    A digital data acquisition system has been combined with a double Frisch gridded ionization chamber for use at both moderated and unmoderated neutron sources at the Los Alamos Neutron Science (LANSCE) facility. The high efficiency of the instrument combined with intense LANSCE beams and new acquisition system permits fission output measurements across 11 orders of magnitude incident neutron energy. The acquisition and analysis system is presented along with the first in-beam performance tests of the setup.

  11. Degree of Rate Control: How Much the Energies of Intermediates and Transition States Control Rates

    DEFF Research Database (Denmark)

    Stegelmann, Carsten; Andreasen, Anders; Campbell, Charles T.

    2009-01-01

    electronic or steric control on the relative energies of the key species. Since these key species are the ones whose relative energies most strongly influence the net reaction rate, they also identify the species whose energetics must be most accurately measured or calculated to achieve an accurate kinetic...

  12. Prompt Fission Gamma-ray Studies at DANCE

    Science.gov (United States)

    Jandel, M.; Rusev, G.; Bond, E. M.; Bredeweg, T. A.; Chadwick, M. B.; Couture, A.; Fowler, M. M.; Haight, R. C.; Kawano, T.; Keksis, A. L.; Mosby, S. M.; O'Donnell, J. M.; Rundberg, R. S.; Stetcu, I.; Talou, P.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Stoyer, M. A.; Haslett, R. J.; Henderson, R. A.; Becker, J. A.; Wu, C. Y.

    Measurements of correlated data on prompt-fission γ-rays (PFG) have been carried out for various actinide isotopes in recent years using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory (LANL). We have developed a model that conveniently parametrizes the correlated data of γ-ray multiplicity and energy. New results on two- dimensional prompt-fission γ-ray multiplicity versus energy distributions from spontaneous fission on 252Cf and neutron-induced fission on 242mAm are presented together with previously obtained results on 233,235U and 239Pu. Correlated PFG data from 252Cf are also compared to results of the detailed theoretical model developed at LANL, for different thresholds of PFG energies. Future plans to measure correlated data on fission fragments, prompt fission neutrons and γ-rays at DANCE are presented.

  13. Recent studies in heavy ion induced fission reactions

    Science.gov (United States)

    Choudhury, R. K.

    2001-08-01

    Nuclear fission process involves large scale shape changes of the nucleus, while it evolves from a nearly spherical configuration to two separated fission fragments. The dynamics of these shape changes in the nuclear many body system is governed by a strong interplay of the collective and single particle degrees of freedom. With the availability of heavy ion accelerators, there has been an impetus to study the nuclear dynamics through the investigations of nucleus--nucleus collisions involving fusion and fission process. From the various investigations carried out in the past years, it is now well recognized that there is large scale damping of collective modes in heavy ion induced fission reactions, which in other words implies that nuclear motion is highly viscous. In recent years, there have been many experimental observations in heavy ion induced fission reactions at medium bombarding energies, which suggest possible occurrence of various non-equilibrium modes of fission such as quasi-fission, fast fission and pre-equilibrium fission, where some of the internal degrees of freedom of the nucleus is not fully equilibrated. We have carried out extensive investigations on the fission fragment angular distributions at near barrier bombarding energies using heavy fissile targets. The measured fragment anisotropies when compared with the standard saddle point model (SSPM) calculations show that for projectile-target systems having zero or low ground state spins, the angular anisotropy exhibits a peak-like behaviour at the sub barrier energies, which cannot be explained by the SSPM calculations. For projectiles or targets with large ground state spins, the anomalous peaking gets washed out due to smearing of the K-distribution by the intrinsic entrance channel spins. Recently studies have been carried out on the spin distributions of fission fragments through the gamma ray multiplicity measurements. The fission fragments acquire spin mainly from two sources: (i) due to

  14. Contributions of complete fusion and break-up–fusion to intermediate mass fragment production in the low energy interaction of 12C and 27Al

    CERN Document Server

    Förtsch, S V; Colleoni, P; Gadioli, E; Gadioli Erba, E; Mairani, A; Steyn, G F; Lawrie, J J; Smit, F D; Connell, S H; Fearick, R W; Thovhogi, T

    2007-01-01

    The measured spectra of a large number of intermediate mass fragments produced at a CM energy of about 110 MeV in the 27Al(12C, x) reaction as well as in its inverse reaction, 12C(27Al, x), are presented. The analysis of these data suggests that, at this energy, the main reaction mechanisms which contribute to the intermediate mass fragment emission are two-nucleus complete fusion and break-up–fusion reactions.

  15. Isospin Diffusion in $^{58}$Ni-Induced Reactions at Intermediate Energies

    CERN Document Server

    Galichet, E; Borderie, B; Colonna, M; Bougault, R; Durand, D; Neindre, N Le; Lopez, O; Manduci, L; Vient, E; Chbihi, A; Frankland, J D; Wieleczko, J P; Dayras, R; Volant, C; Guinet, D C R; Lautesse, P; Parlog, M; Rosato, E; Vigilante, M

    2010-01-01

    Isospin diffusion is probed as a function of the dissipated energy by studying two systems $^{58}$Ni+$^{58}$Ni and $^{58}$Ni+$^{197}$Au, over the incident energy range 52-74\\AM. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the symmetry energy term. A better overall agreement between data and simulations is obtained when using a symmetry term with a potential part linearly increasing with nuclear density. The isospin equilibration time at 52 \\AM{} is estimated to 130$\\pm$10 fm/$c$.

  16. In-beam investigation of ternary fission

    Science.gov (United States)

    Kotte, R.; Fromm, W. D.; Hentschel, E.; Ortlepp, H. G.; Schilling, K. D.; Seidel, W.; Stary, F.; Zwicker, G.

    1988-06-01

    Nuclear fission accompanied by long-range alpha particles has been investigated. Fission was induced by irradiating a natural uranium target with 13.5 MeV deuterons. The alpha energy and angular distributions are similar to those observed in spontaneous or thermal neutron induced fission. The correlation angle between alpha particles and light fission fragments has a most probable value ofbar \\vartheta _{l f - α } = 82.1^circ ± 0.9^circ and a dispersion (FWHM) of Δϑ=18.4°±1.2°. The mean value and dispersion of the energy distribution arebar E_α = 14.8 ± 1.0 MeV and ΔE=9.1±1.2 MeV (FWHM), respectively. The peak-to-valley ratio of the ternary fission fragment mass distribution is found to increase with increasing alpha energy. For near-symmetric mass division, a strong broadening of the angular distribution is observed. The results are discussed in the frame of a multichannel-fission model.

  17. An investigation into electron scattering from pyrazine at intermediate and high energies

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, A. G.; Fuss, M. C. [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 113-bis, 28006 Madrid (Spain); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid (Spain); Gorfinkiel, J. D. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Almeida, D.; Ferreira da Silva, F.; Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Brunger, M. J. [ARC Centre for Antimatter-Matter Studies, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); García, G., E-mail: g.garcia@iff.csic.es [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 113-bis, 28006 Madrid (Spain); Centre for Medical Radiation Physics, University of Wollongong, NSW 2522 (Australia)

    2013-11-14

    Total electron scattering cross sections for pyrazine in the energy range 10–500 eV have been measured with a new magnetically confined electron transmission-beam apparatus. Theoretical differential and integral elastic, as well as integral inelastic, cross sections have been calculated by means of a screening-corrected form of the independent-atom representation (IAM-SCAR) from 10 to 1000 eV incident electron energies. The present experimental and theoretical total cross sections show a good level of agreement, to within 10%, in the overlapping energy range. Consistency of these results with previous calculations (i.e., the R-matrix and Schwinger Multichannel methods) and elastic scattering measurements at lower energies, below 10 eV, is also discussed.

  18. Fission: statistical nucleon pair breaking

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, M. (Instituto Peruano de Energia Nuclear, Lima (Peru))

    1984-06-01

    In order to explain the odd-even effect observed in low energy fission fragment distributions it has been recently required a double mechanism of nucleon pair breaking: before scission (early pair breaking) and at scission (late pair breaking), respectively. In the present work we show that, using the same formulae but considering only the early pair breaking mechanism, one can reproduce fairly well all the available experimental data on the odd-even effects.

  19. Two Pion Production in Nucleon-Nucleon Collisions at Intermediate Energies

    CERN Document Server

    Alvarez-Ruso, L; Hernández, E

    1998-01-01

    We have developed a model for the N N --> N N pi pi reaction and evaluated cross sections for the different charged channels. The low energy part of those channels where the pions can be in an isospin zero state is dominated by N* excitation, driven by an isoscalar source followed by the decay N* --> N (pi pi, T=0, s-wave). At higher energies, and in channels where the pions are not in T=0, Delta excitation mechanisms become relevant.

  20. Poincaré Invariant Three-Body Scattering at Intermediate Energies

    Directory of Open Access Journals (Sweden)

    Polyzou W.N.

    2010-04-01

    Full Text Available Relativistic Faddeev equations for three-body scattering are solved at arbitrary energies in terms of momentum vectors without employing a partial wave decomposition. Relativistic invariance is incorporated within the framework of Poincaré invariant quantum mechanics. Based on a Malfliet-Tjon interaction, observables for elastic and breakup scattering are calculated and compared to non-relativistic ones. The convergence of the Faddeev multiple scattering series is investigated at higher energies.

  1. Determination of minimum impact parameter by modified touching spheres schemes for intermediate energy Coulomb excitation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajiv; Sharma, Shagun [DAV University, Physics Department, Jalandhar (India); Singh, Pradeep [Deenbandhu Chhotu Ram University of Science and Technology, Department of Physics, Murthal (India); Kharab, Rajesh [Kurukshetra University, Department of Physics, Kurukshetra (India)

    2016-02-15

    The energy-independent touching spheres schemes commonly used for the determination of the safe minimum value of the impact parameter for Coulomb excitation experiments are modified through the inclusion of an energy-dependent term. The touching spheres+3fm scheme after modification emerges out to be the best one while touching spheres+4fm scheme is found to be better in its unmodified form. (orig.)

  2. Crystallographic structure of the K intermediate of bacteriorhodopsin: conservation of free energy after photoisomerization of the retinal.

    Science.gov (United States)

    Schobert, Brigitte; Cupp-Vickery, Jill; Hornak, Viktor; Smith, Steven; Lanyi, Janos

    2002-08-23

    The K state, an early intermediate of the bacteriorhodopsin photocycle, contains the excess free energy used for light-driven proton transport. The energy gain must reside in or near the photoisomerized retinal, but in what form has long been an open question. We produced the K intermediate in bacteriorhodopsin crystals in a photostationary state at 100K, with 40% yield, and determined its X-ray diffraction structure to 1.43 A resolution. In independent refinements of data from four crystals, the changes are confined mainly to the photoisomerized retinal. The retinal is 13-cis,15-anti, as known from vibrational spectroscopy. The C13=C14 bond is rotated nearly fully to cis from the initial trans configuration, but the C14-C15 and C15=NZ bonds are partially counter-rotated. This strained geometry keeps the direction of the Schiff base N-H bond vector roughly in the extracellular direction, but the angle of its hydrogen bond with water 402, that connects it to the anionic Asp85 and Asp212, is not optimal. Weakening of this hydrogen bond may account for many of the reported features of the infrared spectrum of K, and for its photoelectric signal, as well as the deprotonation of the Schiff base later in the cycle. Importantly, although 13-cis, the retinal does not assume the expected bent shape of this configuration. Comparison of the calculated energy of the increased angle of C12-C13=C14, that allows this distortion, with the earlier reported calorimetric measurement of the enthalpy gain of the K state indicates that a significant part of the excess energy is conserved in the bond strain at C13.

  3. Modeling Fission Product Sorption in Graphite Structures

    Energy Technology Data Exchange (ETDEWEB)

    Szlufarska, Izabela [University of Wisconsin, Madison, WI (United States); Morgan, Dane [University of Wisconsin, Madison, WI (United States); Allen, Todd [University of Wisconsin, Madison, WI (United States)

    2013-04-08

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission

  4. Survey and screening of intermediate-size photovoltaic total energy and electric applications

    Energy Technology Data Exchange (ETDEWEB)

    Rattin, E.J.

    1978-08-01

    One of the principal objectives of this photovoltaic mission analysis effort has been to identify and evaluate applications for photovoltaic solar energy conversion that could lead to significant contributions to the national energy supply and that would provide attractive opportunities for application experiments aimed at stimulating the adoption of photovoltaic technology. The scope of the study has included applications both for electric-only photovoltaic (PV) systems and for photovoltaic total energy systems (PTES), i.e., systems that provide both photovoltaic electricity and solar thermal energy to meet all or part of the energy demand at a single load point or a group of related load points. In either case, both flat-plate and concentrating systems have been considered and it has been assumed that the thermal energy is collected in and transported by the fluid used in an active cooling system for the photovoltaic cells. Because the efficiency of photovoltaic devices decreases rapidly with increasing temperature and because the operational lifetime of such devices is reduced by prolonged operation at elevated temperatures, a practical upper limit of about 200/sup 0/C (400/sup 0/F) was assumed for the temperature at which arrays can be allowed to be operated. This limitation, in turn, places an upper bound on the temperature at which solar thermal energy is available in PTES applications. An initial screening aimed at identifying the most promising applications has therefore been required, with the expectation that detailed evaluation will be made of only the higher-ranking candidates. A description of the screening procedure that was adopted and a discussion of the results are presented.

  5. EMISSION OF PHOTONS IN SPONTANEOUS FISSION OF CF-252

    NARCIS (Netherlands)

    VANDERPLOEG, H; BACELAR, JCS; BUDA, A; LAURENS, CR; VANDERWOUDE, A; GAARDHOJE, JJ; ZELAZNY, Z; VANTHOF, G; KALANTARNAYESTANAKI, N

    1995-01-01

    High energy photon emission accompanying the spontaneous fission of Cf-252 is measured for different mass splits. The photon yields up to an energy of 20 MeV are obtained at several angles relative to the fission direction. Statistical model calculations are used to interpret the data. The photon yi

  6. Next-Generation Electrochemical Energy Materials for Intermediate Temperature Molten Oxide Fuel Cells and Ion Transport Molten Oxide Membranes.

    Science.gov (United States)

    Belousov, Valery V

    2017-02-21

    High temperature electrochemical devices such as solid oxide fuel cells (SOFCs) and oxygen separators based on ceramic materials are used for efficient energy conversion. These devices generally operate in the temperature range of 800-1000 °C. The high operating temperatures lead to accelerated degradation of the SOFC and oxygen separator materials. To solve this problem, the operating temperatures of these electrochemical devices must be lowered. However, lowering the temperature is accompanied by decreasing the ionic conductivity of fuel cell electrolyte and oxygen separator membrane. Therefore, there is a need to search for alternative electrolyte and membrane materials that have high ionic conductivity at lower temperatures. A great many opportunities exist for molten oxides as electrochemical energy materials. Because of their unique electrochemical properties, the molten oxide innovations can offer significant benefits for improving energy efficiency. In particular, the newly developed electrochemical molten oxide materials show high ionic conductivities at intermediate temperatures (600-800 °C) and could be used in molten oxide fuel cells (MOFCs) and molten oxide membranes (MOMs). The molten oxide materials containing both solid grains and liquid channels at the grain boundaries have advantages compared to the ceramic materials. For example, the molten oxide materials are ductile, which solves a problem of thermal incompatibility (difference in coefficient of thermal expansion, CTE). Besides, the outstanding oxygen selectivity of MOM materials allows us to separate ultrahigh purity oxygen from air. For their part, the MOFC electrolytes show the highest ionic conductivity at intermediate temperatures. To evaluate the potential of molten oxide materials for technological applications, the relationship between the microstructure of these materials and their transport and mechanical properties must be revealed. This Account summarizes the latest results on

  7. Analysis for mass distribution of proton-induced reactions in intermediate energy range

    CERN Document Server

    Xiao Yu Heng

    2002-01-01

    The mass and charge distribution of residual products produced in the spallation reactions needs to be studied, because it can provide useful information for the disposal of nuclear waste and residual radioactivity generated by the spallation neutron target system. In present work, the Many State Dynamical Model (MSDM) is based on the Cascade-Exciton Model (CEM). The authors use it to investigate the mass distribution of Nb, Au and Pb proton-induced reactions in energy range from 100 MeV to 3 GeV. The agreement between the MSDM simulations and the measured data is good in this energy range, and deviations mainly show up in the mass range of 90 - 150 for the high energy proton incident upon Au and Pb

  8. Intermediate energy electron impact excitation of composite vibrational modes in phenol

    Energy Technology Data Exchange (ETDEWEB)

    Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Lopes, M. C. A.; Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Oliveira, E. M. de; Lima, M. A. P. [Instituto de Física ‘Gleb Wataghin,’ Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil); Costa, R. F. da [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, C.P. 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, C.P. 19044, 81531-990 Curitiba, Paraná (Brazil); Silva, G. B. da [Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-05-21

    We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C{sub 6}H{sub 5}OH). The measurements were carried out at incident electron energies in the range 15–40 eV and for scattered-electron angles in the range 10–90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C{sub 6}H{sub 5}OH molecule by electron impact.

  9. Total and elastic electron scattering cross sections from Xe at intermediate and high energies

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, G [Instituto de Matematicas y Fisica Fundamental, CSIC, Serrano 123, 28006 Madrid (Spain); Pablos, J L de [Departamento de Fusion y Particulas Elementales, CIEMAT, Avenida Complutense 22, 28040 Madrid (Spain); Blanco, F [Departamento de Fisica Atomica Molecular y Nuclear, Universidad Complutense de Madrid, 28040 Madrid (Spain); Williart, A [Departamento de Fisica de los Materiales, UNED, Senda del Rey 9, 28040 Madrid (Spain)

    2002-11-28

    Experimental total electron scattering cross sections from Xe in the energy range 300-5000 eV have been obtained with experimental errors of about 3%. The method was based on the measurement of the attenuation of a linear electron beam through a Xe gas cell in combination with an electron spectroscopy technique to analyse the energy of the transmitted electrons. Differential and integral elastic cross sections have been calculated using a scattering potential method which includes relativistic effects. The consistency of our theoretical and experimental results is also discussed in the paper. Finally, analytical formulae depending on two parameters, namely the number of target electrons and the atomic polarizability, are given to reproduce the experimental data for Ne, Ar, Kr and Xe in the energy range 500-10 000 eV.

  10. Intermediate-energy differential and integral cross sections for vibrational excitation in α-tetrahydrofurfuryl alcohol.

    Science.gov (United States)

    Duque, H V; Chiari, L; Jones, D B; Pettifer, Z; da Silva, G B; Limão-Vieira, P; Blanco, F; García, G; White, R D; Lopes, M C A; Brunger, M J

    2014-06-01

    Differential and integral cross section measurements, for incident electron energies in the 20-50 eV range, are reported for excitation of several composite vibrational modes in α-tetrahydrofurfuryl alcohol (THFA). Optimisation and frequency calculations, using GAUSSIAN 09 at the B3LYP/aug-cc-pVDZ level, were also undertaken for the two most abundant conformers of THFA, with results being reported for their respective mode classifications and excitation energies. Those calculations assisted us in the experimental assignments of the composite features observed in our measured energy loss spectra. There are, to the best of our knowledge, no other experimental or theoretical data currently available in the literature against which we can compare the present results.

  11. Fission gas in thoria

    Science.gov (United States)

    Kuganathan, Navaratnarajah; Ghosh, Partha S.; Galvin, Conor O. T.; Arya, Ashok K.; Dutta, Bijon K.; Dey, Gautam K.; Grimes, Robin W.

    2017-03-01

    The fission gases Xe and Kr, formed during normal reactor operation, are known to degrade fuel performance, particularly at high burn-up. Using first-principles density functional theory together with a dispersion correction (DFT + D), in ThO2 we calculate the energetics of neutral and charged point defects, the di-vacancy (DV), different neutral tri-vacancies (NTV), the charged tetravacancy (CTV) defect cluster geometries and their interaction with Xe and Kr. The most favourable incorporation point defect site for Xe or Kr in defective ThO2 is the fully charged thorium vacancy. The lowest energy NTV in larger supercells of ThO2 is NTV3, however, a single Xe atom is most stable when accommodated within a NTV1. The di-vacancy (DV) is a significantly less favoured incorporation site than the NTV1 but the CTV offers about the same incorporation energy. Incorporation of a second gas atom in a NTV is a high energy process and more unfavourable than accommodation within an existing Th vacancy. The bi-NTV (BNTV) cluster geometry studied will accommodate one or two gas atoms with low incorporation energies but the addition of a third gas atom incurs a high energy penalty. The tri-NTV cluster (TNTV) forms a larger space which accommodates three gas atoms but again there is a penalty to accommodate a fourth gas atom. By considering the energy to form the defect sites, solution energies were generated showing that in ThO2-x the most favourable solution equilibrium site is the NTV1 while in ThO2 it is the DV.

  12. New parameterization of effective nucleon-nucleon $t$-matrix interaction for scattering at intermediate energies

    CERN Document Server

    Ladygina, N B

    2008-01-01

    The model suggested by Love and Franey for description of the nucleon-nucleon interaction was used as the base. The new fitting of the model parameters was done in the energy range from 100 MeV up to 1100 MeV. It is based on the modern partial-wave-analysis solution for NN-amplitudes. The three observables: differential cross section, vector analyzing power, and spin correlation coefficient -- were obtained at every energy. The results are compared with existing the experimental data.

  13. A new approach to prompt fission neutron TOF data treatment

    Science.gov (United States)

    Zeynalov, Sh.; Zeynalova, O. V.; Hambsch, F.-J.; Oberstedt, S.

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. A new mathematical approach, applicable to single events, was developed for prompt fission neutron (PFN) time-offlight distribution unfolding. The main goal was to understand the reasons of the long existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of the fission fragments (FF). Since the 252Cf (sf) reaction is one of the main references for nuclear data the understanding of the PFN emission mechanism is very important both for nuclear fission theory and nuclear data. The experimental data were taken with a twin Frisch-grid ionization chamber and a NE213-equivalent neutron detector in an experimental setup similar to the well known work of C. Budtz-Jorgensen and H.-H. Knitter. About 2.5 × 105 coincidences between fission fragment (FF) and neutron detector response to prompt fission neutron detection have been registered (∼ 1.6 × 107 of total recorded fission events). Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12-bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The main goal of this work was a detailed description of the prompt fission neutron treatment.

  14. DSP Algorithms for Fission Fragment and Prompt Fission Neutron Spectroscopy

    Science.gov (United States)

    Zeynalova, O.; Zeynalov, Sh.; Hambsch, F.-J.; Oberstedt, S.; Fabry, I.

    2009-10-01

    Digital signal processing (DSP) algorithms are in high demand for modern nuclear fission investigation due to importance of increase the accuracy of fissile nuclear data for new generation of nuclear power stations. DSP algorithms for fission fragment (FF) and prompt fission neutron (PFN) spectroscopy are described in the present work. The twin Frisch-grid ionization chamber (GTIC) is used to measure the kinetic energy-, mass- and angular distributions of the FF in the 252Cf(SF) reaction. Along with the neutron time-of-flight (TOF) measurement the correlation between neutron emission and FF mass and energy is investigated. The TOF is measured between common cathode of the GTIC and the neutron detector (ND) pulses. Waveform digitizers (WFD) having 12 bit amplitude resolution and 100 MHz sampling frequency are used for the detector pulse sampling. DSP algorithms are developed as recursive procedures to perform the signal processing, similar to those available in various nuclear electronics modules, such as constant fraction discriminator (CFD), pulse shape discriminator (PSD), peak-sensitive analogue-to-digital converter (pADC) and pulse shaping amplifier (PSA). To measure the angle between FF and the cathode plane normal to the GTIC a new algorithm is developed having advantage over the traditional analogue pulse processing schemes. Algorithms are tested by comparing the numerical simulation of the data analysis of the 252Cf(SF) reaction with data available from literature.

  15. Point-by-Point model description of average prompt neutron data as a function of total kinetic energy of fission fragments

    Science.gov (United States)

    Tudora, A.

    2013-03-01

    The experimental data of average prompt neutron multiplicity as a function of total kinetic energy of fragments (TKE) exhibit, especially in the case of 252Cf(SF), different slopes dTKE/dν and different behaviours at low TKE values. The Point-by-Point (PbP) model can describe these different behaviours. The higher slope dTKE/dν and the flattening of at low TKE exhibited by a part of experimental data sets is very well reproduced when the PbP multi-parametric matrix ν(A,TKE) is averaged over a double distribution Y(A,TKE). The lower slope and the almost linear behaviour over the entire TKE range exhibited by other data sets is well described when the same matrix ν(A,TKE) is averaged over a single distribution Y(A). In the case of average prompt neutron energy in SCM as a function of TKE, different dTKE/dɛ slopes are also obtained by averaging the same PbP matrix ɛ(A,TKE) over Y(A,TKE) and over Y(A). The results are exemplified for three fissioning systems benefiting of experimental data as a function of TKE: 252Cf(SF), 235U(nth,f) and 239Pu(nth,f). In the case of 234U(n,f) for the first time it was possible to calculate (TKE) and (TKE) at many incident energies by averaging the PbP multi-parametric matrices over the experimental Y(A,TKE) distributions recently measured at IRMM for 14 incident energies in the range 0.3-5 MeV. The results revealed that the slope dTKE/dν does not vary with the incident energy and the flattening of at low TKE values is more pronounced at low incident energies. The average model parameters dependences on TKE resulted from the PbP treatment allow the use of the most probable fragmentation approach, having the great advantage to provide results at many TKE values in a very short computing time compared to PbP and Monte Carlo treatments.

  16. Intermediate energy cross sections for electron-impact vibrational-excitation of pyrimidine

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Ellis-Gibbings, L.; García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); School of Biology, Chemistry and Forensic Science, University of Wolverhampton, Wolverhampton WV1 1LY (United Kingdom); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-09-07

    We report differential cross sections (DCSs) and integral cross sections (ICSs) for electron-impact vibrational-excitation of pyrimidine, at incident electron energies in the range 15–50 eV. The scattered electron angular range for the DCS measurements was 15°–90°. The measurements at the DCS-level are the first to be reported for vibrational-excitation in pyrimidine via electron impact, while for the ICS we extend the results from the only previous condensed-phase study [P. L. Levesque, M. Michaud, and L. Sanche, J. Chem. Phys. 122, 094701 (2005)], for electron energies ⩽12 eV, to higher energies. Interestingly, the trend in the magnitude of the lower energy condensed-phase ICSs is much smaller when compared to the corresponding gas phase results. As there is no evidence for the existence of any shape-resonances, in the available pyrimidine total cross sections [Baek et al., Phys. Rev. A 88, 032702 (2013); Fuss et al., ibid. 88, 042702 (2013)], between 10 and 20 eV, this mismatch in absolute magnitude between the condensed-phase and gas-phase ICSs might be indicative for collective-behaviour effects in the condensed-phase results.

  17. Planck intermediate results: XLIII. Spectral energy distribution of dust in clusters of galaxies

    DEFF Research Database (Denmark)

    Adam, R.; Ade, P. A R; Aghanim, N.;

    2016-01-01

    Although infrared (IR) overall dust emission from clusters of galaxies has been statistically detected using data from the Infrared Astronomical Satellite (IRAS), it has not been possible to sample the spectral energy distribution (SED) of this emission over its peak, and thus to break the degene...

  18. Intermediate Energies for Nuclear Astrophysics and the Development of a Position Sensitive Microstrip Detector System

    Energy Technology Data Exchange (ETDEWEB)

    Sobotka, Lee G. [Washington Univ., St. Louis, MO (United States); Blackmon, J. [Louisiana State Univ., Baton Rouge, LA (United States); Bertulani, C. [Texas A & M Univ., College Station, TX (United States)

    2015-12-30

    The chemical elements are made at astrophysical sites through a sequence of nuclear reactions often involving unstable nuclei. The overarching aim of this project is to construct a system that allows for the inverse process of nucleosynthesis (i.e. breakup of heavier nuclei into lighter ones) to be studied in high efficiency. The specific problem to be overcome with this grant is inadequate dynamic range and (triggering) threshold to detect the products of the breakup which include both heavy ions (with large energy and large deposited energy in a detector system) and protons (with little energy and deposited energy.) Early on in the grant we provided both TAMU and RIKEN (the site of the eventual experiments) with working systems based on the existing technology. This technology could be used with either an external preamplifier that was to be designed and fabricated by our RIKEN collaborators or upgraded by replacing the existing chip with one we designed. The RIKEN external preamplifier project never can to completion but our revised chip was designed, fabricated, used in a test experiment and performs as required.

  19. Characteristics of spontaneous fission of 250No

    Science.gov (United States)

    Svirikhin, A. I.; Andreev, A. V.; Yeremin, A. V.; Izosimov, I. N.; Isaev, A. V.; Kuznetsov, A. N.; Kuznetsova, A. A.; Malyshev, O. N.; Popeko, A. G.; Popov, Y. A.; Sokol, E. A.; Chelnokov, M. L.; Chepigin, V. I.; Schneidman, T. M.; Gall, B.; Dorvaux, O.; Brione, P.; Hauschild, K.; Lopez-Martenz, A.; Rezynkina, K.; Mullins, S.; Jones, P.; Mosat, P.

    2017-07-01

    This study describes an experiment on investigating the properties of spontaneous fission of shortlived neutron-deficient nuclei synthesized in the reaction of complete fusion 48Ca + 204Pb = 252No*. The experiment is performed using the SHELS separator and the beam of multicharged ions at U-400 accelerator (LNR, JINR). Two activities undergoing spontaneous fission, which can be related to the ground and isomeric states of 250No nucleus, are registered. The half-lives, total kinetic energies of fission fragments, and neutron multiplicities are measured for the short-lived nuclei. The average number of neutrons per fission for the activity with t 1/2 = 5.1 ± 0.3 μs is = 4.38 ± 0.13 μs, and for nuclei with the half-life t 1/2 = 36 ± 3 μs it is xxxxx.

  20. Theoretical and experimental investigation of (e,2e) ionization of argon 3p in asymmetric kinematics at intermediate energy

    Science.gov (United States)

    Amami, Sadek; Ulu, Melike; Ozer, Zehra Nur; Yavuz, Murat; Kazgoz, Suay; Dogan, Mevlut; Zatsarinny, Oleg; Bartschat, Klaus; Madison, Don

    2014-07-01

    The field of electron-impact ionization of atoms, or (e,2e), has provided significant detailed information about the physics of collisions. For ionization of hydrogen and helium, essentially exact numerical methods have been developed which can correctly predict what will happen. For larger atoms, we do not have theories of comparable accuracy. Considerable attention has been given to ionization of inert gases and, of the inert gases, argon seems to be the most difficult target for theory. There have been several studies comparing experiment and perturbative theoretical approaches over the last few decades, and generally qualitative but not quantitative agreement is found for intermediate energy incident electrons. Recently a nonperturbative method, the B-spline R-matrix (BSR) method, was introduced which appears to be very promising for ionization of heavier atoms. We have recently performed an experimental and theoretical investigation for ionization of argon, and we found that, although the BSR gave reasonably good agreement with experiment, there were also some cases of significant disagreement. The previous study was performed for 200-eV incident electrons and ejected electron energies of 15 and 20 eV. The purpose of the present work is to extend this study to a much larger range of ejected electron energies (15-50 eV) to see if theory gets better with increasing energy as would be expected for a perturbative calculation. The experimental results are compared with both the BSR and two different perturbative calculations.

  1. Experimental measurement of radiological penumbra associated with intermediate energy x-rays (1 MV) and small radiosurgery field sizes.

    Science.gov (United States)

    Keller, Brian M; Beachey, David J; Pignol, Jean-Philippe

    2007-10-01

    Stereotactic radiosurgery is used to treat intracranial lesions with a high degree of accuracy. At the present time, x-ray energies at or above Co-60 gamma rays are used. Previous Monte Carlo simulations have demonstrated that intermediate energy x-ray photons or IEPs (defined to be photons in the energy range of 0.2-1.2 MeV), combined with small field sizes, produce a reduced radiological penumbra leading to a sharper dose gradient, improved dose homogeneity and sparing of critical anatomy adjacent to the target volume. This hypothesis is based on the fact that, for small x-ray fields, a dose outside the treatment volume is dictated mainly by the range of electrons set into motion by x-ray photons. The purpose of this work is: (1) to produce intermediate energy x rays using a detuned medical linear accelerator, (2) to characterize the energy of this beam, (3) to measure the radiological penumbra for IEPs and small fields to compare with that produced by 6 MV x rays or Co-60, and (4) to compare these experimental measurements with Monte Carlo computer simulations. The maximum photon energy of our IEP x-ray spectrum was measured to be 1.2 MeV. Gafchromic EBT films (ISP Technologies, Wayne, NJ) were irradiated and read using a novel digital microscopy imaging system with high spatial resolution. Under identical irradiation conditions the measured radiological penumbra widths (80%-20% distance), for field sizes ranging from 0.3 x 0.3 to 4.0 x 4.0 cm2, varied from 0.3-0.77 mm (1.2 MV) and from 1.1-2.1 mm (6 MV). Even more dramatic were the differences found when comparing the 90%-10% or the 95%-5% widths, which are in fact more significant in radiotherapy. Monte Carlo simulations agreed well with the experimental findings. The reduction in radiological penumbra could be substantial for specific clinical situations such as in the treatment of an ocular melanoma abutting the macula or for the treatment of functional disorders such as trigeminal neuralgia (a nonlethal

  2. Excitation functions of proton-proton elastic scattering at intermediate energies

    Science.gov (United States)

    Scobel, W.; Dohrmann, F.; Bisplinghoff, J.; Hinterberger, F.; Scobel, W.; Altmeier, M.; Bauer, F.; Bisplinghoff, J.; Bissel, T.; Bollmann, R.; Busch, M.; Büßer, K.; Cloth, P.; Danie, R.; Diehl, O.; Dohrmann, F.; Engelhardt, H. P.; Ernst, J.; Eversheim, P. D.; Felden, O.; Flammer, J.; Gasthuber, M.; Gebel, R.; Greiff, J.; Groß, A.; Groß-Hardt, R.; Hebbel, K.; Hinterberger, F.; Hüskes, T.; Jahn, R.; Koch, I.; Langkau, R.; Lindemann, T.; Lindlein, J.; Maier, R.; Maschuw, R.; Mayer-Kuckuk, T.; Pfuff, M.; Prasuhn, D.; Rohdjeß, H.; Rosendaal, D.; von Rossen, P.; Schirm, N.; Schulz-Rojahn, M.; Schwarz, V.; Scobel, W.; Steinbeck, S.; Sterzenbach, G.; Thomas, S.; Trelle, H. J.; Walker, M.; Weise, E.; Wellinghausen, A.; Woller, K.; Ziegler, R.; EDDA Collaboration at COSY; EDDA Collaboration

    1998-03-01

    Excitation functions of proton-proton elastic cross sections have been measured in narrow momentum steps Δp = 28 MeV/c in the kinetic energy range from 0.5 to 2.5 GeV and the angular range 35° ≤ Θcm ≤ 90° with a detector providing ΔΘcm ≈ 1.4° resolution and 82% solid angle coverage. Measurements have been performed continuously during projectile acceleration in the Cooler Synchrotron COSY with an internal CH 2 fiber target; background corrections were derived from measurements with a carbon fiber target and from Monte Carlo simulations of inelastic pp contributions. Particular care was taken to monitor the luminosity as a function of beam energy. The results provide excitation functions and angular distributions of unprecedented precision and internal consistency. The measured cross sections are compared to recent phase shift analyses, and their impact on the present solution SM97 [1] is discussed.

  3. Impact of thermal and intermediate energy neutrons on the semiconductor memories for the CERN accelerators

    CERN Document Server

    Cecchetto, Matteo; Gerardin, Simone

    A wide quantity of SRAM memories are employed along the Large Hadron Collider (LHC), the main CERN accelerator, and they are subjected to high levels of ionizing radiations which compromise the reliability of these devices. The Single Event Effect (SEE) qualification for components to be used in the complex high-energy accelerator at CERN relies on the characterization of two cross sections: 200-MeV protons and thermal neutrons. However, due to cost and time constraints, it is not always possible to characterize the SEE response of components to thermal neutrons, which is often regarded as negligible for components without borophosphosilicate glass (BPSG). Nevertheless, as recent studies show, the sensitivity of deep sub-micron technologies to thermal neutrons has increased owing to the presence of Boron 10 as a dopant and contact contaminant. The very large thermal neutron fluxes relative to high-energy hadron fluxes in some of the heavily shielded accelerator areas imply that even comparatively small therm...

  4. Vector and tensor analysing powers in deuteron-proton breakup reactions at intermediate energies

    CERN Document Server

    Chiladze, D; Dymov, S; Glagolev, V; Hartmann, M; Hejny, V; Kacharava, A K; Keshelashvili, I; Khoukaz, A; Koch, H R; Komarov, V; Kulessa, P; Kulikov, A; Macharashvili, G; Maeda, Y; Mersmann, T; Merzliakov, S; Mikirtytchiants, S; Mussgiller, A; Nioradze, M; Ohm, H; Rathmann, F; Schleichert, R; Stein, H J; Ströher, H; Uzikov, Y; Wilkin, C; Yaschenko, S; Uzikov, Yu.

    2006-01-01

    Vector and tensor analysing powers of the d(pol)p->(pp)n (charge-exchange) and d(pol)p->(pn)p (non-charge-exchange) breakup reactions have been measured with the ANKE spectrometer at the COSY ring at a deuteron beam energy of 1170 MeV for small momentum transfers to the low excitation energy (pp) or (pn) systems. A quantitative understanding of the values of A_xx and A_yy for the charge-exchange reaction is provided by impulse approximation calculations. The data suggest that spin-flip isospin-flip transitions, which dominate the charge-exchange breakup of the deuteron, are also important in the non-charge-exchange reaction.

  5. Spin observables in deuteron-proton radiative capture at intermediate energies

    CERN Document Server

    Mehmandoost-Khajeh-Dad, A A; Bacelar, J C S; Van den Berg, A M; Castelijns, R; Deltuva, A; Van Garderen, E; Glöckle, W; Golak, J; Kalantar-Nayestanaki, N; Kamada, H; Koohi-Fayegh-Dehkordi, R; L"ohner, H; Mahjour-Shafiei, M; Mardanpur, H; Messchendorp, J G; Nogga, A; Sauer, P; Shende, S V; Skibinski, R; Witala, H; W"ortche, H J

    2005-01-01

    A radiative deuteron-proton capture experiment was carried out at KVI using polarized-deuteron beams at incident energies of 55, 66.5, and 90 MeV/nucleon. Vector and tensor-analyzing powers were obtained for a large angular range. The results are interpreted with the help of Faddeev calculations, which are based on modern two- and three-nucleon potentials. Our data are described well by the calculations, and disagree significantly with the observed tensor anomaly at RCNP.

  6. Pre-equilibrium particle emission in the heavy ion collisions at intermediate energy

    Science.gov (United States)

    Bellia, G.; Agodi, C.; Alba, R.; Coniglione, R.; Zoppo, A. Del; Finocchiaro, P.; Loukachine, K.; Maiolino, C.; Migneco, E.; Peghaire, A.; Piattelli, P.; Santonocito, D.; Sapienza, P.

    Hard photons and high energy protons from Ar and Xe induced reactions at 44 MeV/u were analysed in a series of experiments performed with the detector MEDEA. A careful analysis shows a strong correlation between hard γ and fast protons giving an unambiguous signature of the n-p first chance bremsstrahlung hypothesis. Some preliminary results on the emission of fast protons are reported.

  7. A hadron-nucleus collision event generator for simulations at intermediate energies

    CERN Document Server

    Ackerstaff, K; Bollmann, R

    2002-01-01

    Several available codes for hadronic event generation and shower simulation are discussed and their predictions are compared to experimental data in order to obtain a satisfactory description of hadronic processes in Monte Carlo studies of detector systems for medium energy experiments. The most reasonable description is found for the intra-nuclear-cascade (INC) model of Bertini which employs microscopic description of the INC, taking into account elastic and inelastic pion-nucleon and nucleon-nucleon scattering. The isobar model of Sternheimer and Lindenbaum is used to simulate the inelastic elementary collisions inside the nucleus via formation and decay of the DELTA sub 3 sub 3 -resonance which, however, limits the model at higher energies. To overcome this limitation, the INC model has been extended by using the resonance model of the HADRIN code, considering all resonances in elementary collisions contributing more than 2% to the total cross-section up to kinetic energies of 5 GeV. In addition, angular d...

  8. The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts

    CERN Document Server

    Mandelbaum, Rachel; Bridle, Sarah; Abdalla, Filipe B; Brough, Sarah; Colless, Matthew; Couch, Warrick; Croom, Scott; Davis, Tamara; Drinkwater, Michael J; Forster, Karl; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, Tornado; Madore, Barry; Martin, Chris; Pimbblet, Kevin; Poole, Gregory B; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted

    2009-01-01

    Correlations between the intrinsic shapes of galaxy pairs, and between the intrinsic shapes of galaxies and the large-scale density field, may be induced by tidal fields. These correlations, which have been detected at low redshifts (z<0.35) for bright red galaxies in the Sloan Digital Sky Survey (SDSS), and for which upper limits exist for blue galaxies at z~0.1, provide a window into galaxy formation and evolution, and are also an important contaminant for current and future weak lensing surveys. Measurements of these alignments at intermediate redshifts (z~0.6) that are more relevant for cosmic shear observations are very important for understanding the origin and redshift evolution of these alignments, and for minimising their impact on weak lensing measurements. We present the first such intermediate-redshift measurement for blue galaxies, using galaxy shape measurements from SDSS and spectroscopic redshifts from the WiggleZ Dark Energy Survey. Our null detection allows us to place upper limits on the...

  9. Recoil properties of radionuclides formed in photospallation reactions on complex nuclei at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Haba, Hiromitsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Sakamoto, Koh; Matsumura, Hiroshi [Kanazawa Univ., Faculty of Science, Kanazawa, Ishikawa (Japan); Oura, Yasuji [Tokyo Metropolitan Univ., Department of Chemistry, Tokyo (Japan); Shibata, Seiichi [Kyoto Univ., Research Reactor Institute, Kumatori, Osaka (Japan); Furukawa, Michiaki [Yokkaichi Univ., Faculty of Environmental and Information Sciences, Yokkaichi, Mie (Japan); Fujiwara, Ichiro [Otemon-Gakuin Univ., Faculty of Economics, Ibaraki, Osaka (Japan)

    2001-03-01

    A short review is given on our studies of recoil properties of radionuclides formed in photospallation reactions induced by bremsstrahlung of end-point energies (E{sub 0}) from 600 to 1100 MeV, in which the thick-target thick-catcher method was employed. The measurements have been successful on 14, 24, 26, 31, 21 and 20 nuclides from {sup nat}V, {sup nat}Cu, {sup 93}Nb, {sup nat}Ag, {sup nat}Ta, and {sup 197}Au, respectively. Reflecting the resonance character in a photonuclear reaction, the mean ranges FW and BW in the forward and backward directions, respectively, are E{sub 0}-independent at the studied energies and classified into two groups accounting for the ({gamma}, xn) (x {>=} 1) and ({gamma}, xnyp) (x, y {>=} 1) processes. The forward-to-backward ratios (F/B) are independent of the mass difference ({delta}A) between a product (A{sub p}) and a target (A{sub t}) and also of A{sub t}. The kinematic properties of the product nuclei were analyzed by the two-step vector velocity model. The forward velocity {nu} after the first step of photon-reaction is quite different from that of proton-reaction at proton energies of E{sub p} {<=} 3 GeV, though the difference disappears at higher energies. On the other hand, the mean kinetic energy T of the residual nucleus in the second step is almost equal to that of proton-reaction irrespective of E{sub p}. A comparison with T values calculated by the PICA (Photon-Induced Intranuclear Cascade Analysis) code at E{sub 0}=400 MeV was also performed. It was found that although the code well reproduces the experimental results of {sup nat}V and {sup nat}Cu, the same calculation for heavier targets gives T values lower than the experimental results, indicating some nuclear-structure effect, such as a medium effect notably at A{sub t} {>=} 100. An average kinetic energy carried off by the emitted particles {epsilon}{sub s}=T/({delta}A/A{sub t}) of both photon- and proton-reactions seem to increase with an increase of A{sub t} up

  10. Progress in physics design of fusion-fission hybrid energy reactor%次临界能源堆物理设计进展

    Institute of Scientific and Technical Information of China (English)

    李茂生; 贾建平; 程和平; 蒋洁琼; 栗再新; 杨永伟; 吴宏春; 师学明; 刘荣; 鹿心鑫; 朱通华; 王新华; 余泳; 严钧; 唐涛

    2014-01-01

    聚变-裂变混合能源堆包括聚变中子源和次临界能源堆,主要目标是生产电能。回顾了国内外混合堆的发展历史,给出混合能源堆设计的边界条件和约束条件,说明次临界能源堆以铀锆合金为燃料、水为冷却剂的设计思想。利用输运燃耗耦合程序 MCORGS 计算了混合能源的燃耗,给出了中子有效增殖因数、能量放大倍数和氚增殖比等物理量随时间的变化。通过分析能谱和重要核素随燃耗时间的变化,说明混合能源堆与核燃料增殖、核废料嬗变混合堆的不同特点。论述了混合堆的热工设计并进行了安全分析。对于燃耗数值模拟程序,通过多家对算,保证其计算结果的可信性。针对次临界能源堆的特点,利用贫铀球壳建立了贫铀聚乙烯装置和贫铀 LiH 装置,并且专门设计加工了天然铀装置,开展铀裂变率、造钚率、产氚率等中子学积分实验,验证了数值模拟的可靠性。%In this paper,we propose a preliminary design for a fusion-fission hybrid energy reactor (FFHER),based on cur-rent fusion science and technology and well-developed fission technology.Design rules are listed and a primary concept blanket with uranium alloy as fuel and water as coolant is put forward.The uranium fuel can be natural uranium,LWR spent fuel,or de-pleted uranium.The FFHER design can increase the utilization rate of uranium in a comparatively simple way to sustain the de-velopment of nuclear energy.The interaction between the fusion neutron and the uranium fuel with the aim of achieving greater energy multiplication and tritium sustainability is studied.Other concept hybrid reactor designs are also reviewed.Integral neu-tron experiments were carried out to verify the credibility of our proposed physical design.The combination of the physical design with the related thermal hydraulic design,alloy fuel manufacture,and nuclear fuel cycle programs provides the

  11. Apparent Clustering of Intermediate-redshift Galaxies as a Probe of Dark Energy

    CERN Document Server

    Matsubara, T; Matsubara, Takahiko; Szalay, Alexander S.

    2002-01-01

    We show the apparent redshift-space clustering of galaxies in redshift range of 0.2-0.4 provides surprisingly useful constraints on dark energy component in the universe, because of the right balance between the density of objects and the survey depth. We apply Fisher matrix analyses to the the Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS), as a concrete example. Possible degeneracies in the evolution of the equation of state (EOS) and the other cosmological parameters are clarified.

  12. Positron-Lithium Atom and Electron-Lithium Atom Scattering Systems at Intermediate and High Energies

    Institute of Scientific and Technical Information of China (English)

    K. Ratnavelu; S. Y. Ng

    2006-01-01

    @@ The coupled-channel optical method is used to study positron scattering by atomic lithium at energies ranging from the ionization threshold to 60 eV. The present method simultaneously treats the target channels and the positronium (Ps) channels in the coupled-channel method together with the continuum effects via an ab-initio optical potential. Ionization, elastic and inelastic cross sections in target channels, and the total cross section are also reported and compared with other theoretical and experimental data. A comparative study with the corresponding electron-lithium data is also reported.

  13. Measurement of the Higgs decay to electroweak bosons at low and intermediate CLIC energies

    CERN Document Server

    AUTHOR|(SzGeCERN)471575; Milutinovic-Dumbelovic, Gordana; Pandurovic, Mila; Lukic, Strahinja

    2016-01-01

    In this paper a simulation of measurements of the Higgs boson decay to electroweak bosons in $e^+e^-$ collisions at CLIC is presented. Higgs boson production and subsequent $H\\rightarrow ZZ^\\ast$ and $H\\rightarrow WW^\\ast$ decay processes were simulated alongside the relevant background processes at 350 GeV and 1.4 TeV center-of-mass energy. Full detector simulation and event reconstruction were used under realistic beam conditions. The achievable statistical precision of the measured product of the Higgs production cross section and the branching ratio for the analysed decays has been determined.

  14. A study of stopping power in nuclear reactions at intermediate energies

    CERN Document Server

    Lehaut, G; Lopez, O

    2010-01-01

    We show a systematic experimental study based on INDRA data of the stopping power in central symmetric nuclear reactions. Total mass of the systems goes from 80 to 400 nucleons while the incident energy range is from 12 AMeV to 100 AMeV. The role of isospin diffusion at 32 and 45 MeV/nucleon with 124,136Xe projectiles on 112,124Sn targets performed at GANIL is also discussed. Results suggest a strong memory of the entrance channel above 20 AMeV/A (nuclear transparency) and, as such, constitute valuable tests of the microscopic transport models.

  15. Elastic differential cross sections of electron scattering by CF4 at intermediate energies

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The elastic differential cross sections(DCS)for electron scattering from CF4 are calculated at six impact energies(in 100-700 eV)employing the independent atom model(IAM)with partial waves. The atoms are presented by a model complex optical potential which is composed of static, exchange, polarization, and absorption terms. The electron density function ρ(r) is obtained by a fitting procedue to the Dirac-Hartree-Fock-Slater sef-consistent data. Compared with available experimental data, the present approach gives good results.

  16. The knockout reaction of 15C on a 9Be target at intermediate energies

    Science.gov (United States)

    Sadeghi, H.; Fereidonnejad, R.; Ghambari, M.

    2016-05-01

    In this work, neutron knockout reactions of 15C on a 9Be target at energy 103 and 250 MeV/nucleon are studied. Using the Eikonal approximation of the Glauber model, total neutron removal cross sections, the stripping and diffractive cross sections as well as 14C longitudinal momentum distributions are determined in both 15C ground state and exited states of the wave function. We compared the results of our calculations with the available experimental data obtained recently. The calculated cross sections of 15C and 14C reactions, as well as the momentum distribution are in relatively good agreement with available data.

  17. Microscopic analysis of p^{10}B scattering at the intermediate energies

    CERN Document Server

    Dzhazairov-Kahramanov, Albert; Krassovitskiy, Pavel

    2016-01-01

    The differential cross sections of the p^{10}B scattering at energies of 197, 600 and 1000 MeV have been calculated within the framework of the Glauber theory. The operator of multiple scattering takes into account the contributions of single and double collisions. The contributions from protons scattering on the nucleons of different shells have been estimated in the single-scattering cross-section. The comparison with the experiment at 197 MeV and with DWBA calculation showed the adequate description of cross-sections in the region of the front angles.

  18. Enhanced trigger for the NIFFTE fissionTPC in presence of high-rate alpha backgrounds

    Science.gov (United States)

    Bundgaard, Jeremy; Niffte Collaboration

    2015-10-01

    Nuclear physics and nuclear energy communities call for new, high precision measurements to improve existing fission models and design next generation reactors. The Neutron Induced Fission Fragment Tracking experiment (NIFFTE) has developed the fission Time Projection Chamber (fissionTPC) to measure neutron induced fission with unrivaled precision. The fissionTPC is annually deployed to the Weapons Neutron Research facility at Los Alamos Neutron Science Center where it operates with a neutron beam passing axially through the drift volume, irradiating heavy actinide targets to induce fission. The fissionTPC was developed at the Lawrence Livermore National Laboratory's TPC lab, where it measures spontaneous fission from radioactive sources to characterize detector response, improve performance, and evolve the design. To measure 244Cm, we've developed a fission trigger to reduce the data rate from alpha tracks while maintaining a high fission detection efficiency. In beam, alphas from 239Pu are a large background when detecting fission fragments; implementing the fission trigger will greatly reduce this background. The implementation of the cathode fission trigger in the fissionTPC will be presented along with a detailed study of its efficiency.

  19. Isospin Momentum-Dependent Interaction and Its Role on the Isospin Fractionation Ratio in Intermediate Energy Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Ye; GUO Wen-Jun; XING Yong-Zhong; LEE Xi-Guo

    2005-01-01

    @@ We investigate the role of isospin momentum-dependent interaction on the isospin fractionation ratio and its dynamical mechanism in the intermediate energy heavy ion collisions, by inserting an isospin degree of freedom into the momentum-dependent interaction to obtain an isospin momentum-dependent interaction given in a form practically usable in the isospin-dependent quantum molecular dynamics model It is found that the isospin momentum-dependent interaction brings an important isospin effect into the isospin fractionation ratio. In particular, the isospin momentum-dependent interaction reduces obviously the reduction of isospin fractionation ratio. Thus the isospin dependence of momentum-dependent interaction is thus important for studying accurately the equation of state of isospin asymmetry nuclear matter.

  20. Intermediate steps towards the 2000 W society in Switzerland: An energy-economic scenario analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Thorsten F.; Kypreos, Socrates [Energy Economics Group, Paul Scherrer Institute (PSI) CH-5232 Villigen (Switzerland); Barreto, Leonardo [Energy Economics Group, Paul Scherrer Institute (PSI) CH-5232 Villigen (Switzerland); Austrian Energy Agency, A-1060 Vienna (Austria); Wokaun, Alexander [General Energy, Paul Scherrer Institute (PSI) CH-5232 Villigen (Switzerland)

    2008-04-15

    In the future, sustainable development under the umbrella of the 2000 W society could be of major interest. Could the target of the 2000 W society, i.e. a primary energy per capita (PEC) consumption of 2000 W, be realized until 2050? Various combinations of PEC and CO{sub 2} targets are tested, and the additional costs to be paid by the society are estimated. The assessment is carried out with the Swiss MARKAL model, a bottom-up energy-system model projecting future technology investments for Switzerland. The analysis reveals that the 2000 W society should be seen as a long-term goal. For all contemplated scenarios, a PEC consumption of 3500 W per capita (w/cap) is feasible in the year 2050. However, strong PEC consumption targets can reduce CO{sub 2} emissions to an equivalent of 5% per decade at maximum. For stronger CO{sub 2} emission reduction goals, corresponding targets must be formulated explicitly. At an oil price of 75 US${sub 2000}/bbl in 2050, the additional (cumulative, discounted) costs to reach a 10% CO{sub 2} reduction per decade combined with a 3500 W per capita target amount to about 40 billion US${sub 2000}. On the contrary, to reach pure CO{sub 2} reduction targets is drastically cheaper, challenging the vision of the 2000 W society. (author)

  1. A fission-fragment-sensitive target for X-ray spectroscopy in neutron-induced fission

    CERN Document Server

    Ethvignot, T; Giot, L; Casoli, P; Nelson, R O

    2002-01-01

    A fission-fragment-sensitive detector built for low-energy photon spectroscopy applications at the WNR 'white' neutron source at Los Alamos is described. The detector consists of eight layers of thin photovoltaic cells, onto which 1 mg/cm sup 2 of pure sup 2 sup 3 sup 8 U is deposited. The detector serves as an active target to select fission events from background and other reaction channels. The fairly small thickness of the detector with respect to transmission of 20-50 keV photons permits the measurement of prompt fission-fragment X-rays. Results with the GEANIE photon spectrometer are presented.

  2. Characterization of the scission point from fission-fragment velocities

    CERN Document Server

    Caamaño, M; Delaune, O; Schmidt, K -H; Schmitt, C; Audouin, L; Bacri, C -O; Benlliure, J; Casarejos, E; Derkx, X; Fernández-Domínguez, B; Gaudefroy, L; Golabek, C; Jurado, B; Lemasson, A; Ramos, D; Rodríguez-Tajes, C; Roger, T; Shrivastava, A

    2015-01-01

    The isotopic-yield distributions and kinematic properties of fragments produced in transfer-induced fission of 240Pu and fusion-induced fission of 250Cf, with 9 MeV and 45 MeV of excitation energy respectively, were measured in inverse kinematics with the spectrometer VAMOS. The kinematic properties of identified fission fragments allow to derive properties of the scission configuration such as the distance between fragments, the total kinetic energy, the neutron multiplicity, the total excitation energy, and, for the first time, the proton- and neutron-number sharing during the emergence of the fragments. These properties of the scission point are studied as functions of the fragment atomic number. The correlation between these observables, gathered in one single experiment and for two different fissioning systems at different excitation energies, give valuable information for the understanding and modeling of the fission process.

  3. Chiral symmetry restoration in heavy-ion collisions at intermediate energies

    CERN Document Server

    Palmese, A; Seifert, E; Steinert, T; Moreau, P; Bratkovskaya, E L

    2016-01-01

    We study the effect of the chiral symmetry restoration (CSR) on heavy-ion collisions observables in the energy range $\\sqrt{s_{NN}}$=3-20 GeV within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the non-linear $\\sigma-\\omega$ model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations.

  4. Planck intermediate results. XLIII. The spectral energy distribution of dust in clusters of galaxies

    CERN Document Server

    Adam, R; Aghanim, N; Ashdown, M; Aumont, J; Baccigalupi, C; Barreiro, R B; Bartolo, N; Battaner, E; Benabed, K; Benoit-Lévy, A; Bersanelli, M; Bielewicz, P; Bikmaev, I; Bonaldi, A; Bond, J R; Borrill, J; Bouchet, F R; Burenin, R; Burigana, C; Calabrese, E; Cardoso, J -F; Catalano, A; Chiang, H C; Christensen, P R; Churazov, E; Colombo, L P L; Combet, C; Comis, B; Couchot, F; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davis, R J; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Désert, F -X; Diego, J M; Dole, H; Doré, O; Douspis, M; Ducout, A; Dupac, X; Elsner, F; Enßlin, T A; Finelli, F; Forni, O; Frailis, M; Fraisse, A A; Franceschi, E; Galeotta, S; Ganga, K; Génova-Santos, R T; Giard, M; Giraud-Héraud, Y; Gjerløw, E; González-Nuevo, J; Gregorio, A; Gruppuso, A; Gudmundsson, J E; Hansen, F K; Harrison, D L; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Hornstrup, A; Hovest, W; Hurier, G; Jaffe, A H; Jaffe, T R; Jones, W C; Keihänen, E; Keskitalo, R; Khamitov, I; Kisner, T S; Kneissl, R; Knoche, J; Kunz, M; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Lattanzi, M; Lawrence, C R; Leonardi, R; Levrier, F; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Macías-Pérez, J F; Maffei, B; Maggio, G; Mandolesi, N; Mangilli, A; Maris, M; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Melchiorri, A; Mennella, A; Migliaccio, M; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Nørgaard-Nielsen, H U; Novikov, D; Novikov, I; Oxborrow, C A; Pagano, L; Pajot, F; Paoletti, D; Pasian, F; Perdereau, O; Perotto, L; Pettorino, V; Piacentini, F; Piat, M; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Pratt, G W; Prunet, S; Puget, J -L; Rachen, J P; Rebolo, R; Reinecke, M; Remazeilles, M; Renault, C; Renzi, A; Ristorcelli, I; Rocha, G; Rosset, C; Rossetti, M; Roudier, G; Rubiño-Martín, J A; Rusholme, B; Santos, D; Savelainen, M; Savini, G; Scott, D; Stolyarov, V; Stompor, R; Sudiwala, R; Sunyaev, R; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Terenzi, L; Toffolatti, L; Tomasi, M; Tristram, M; Tucci, M; Valenziano, L; Valiviita, J; Van Tent, F; Vielva, P; Villa, F; Wade, L A; Wehus, I K; Yvon, D; Zacchei, A; Zonca, A

    2016-01-01

    Although infrared (IR) overall dust emission from clusters of galaxies has been statistically detected using data from the Infrared Astronomical Satellite (IRAS), it has not been possible to sample the spectral energy distribution (SED) of this emission over its peak, and thus to break the degeneracy between dust temperature and mass. By complementing the IRAS spectral coverage with Planck satellite data from 100 to 857 GHz, we provide new constraints on the IR spectrum of thermal dust emission in clusters of galaxies. We achieve this by using a stacking approach for a sample of several hundred objects from the Planck cluster sample; this procedure averages out fluctuations from the IR sky, allowing us to reach a significant detection of the faint cluster contribution. We also use the large frequency range probed by Planck, together with component-separation techniques, to remove the contamination from both cosmic microwave background anisotropies and the thermal Sunyaev-Zeldovich effect (tSZ) signal, which d...

  5. A Precision Measurement of pp Elastic Scattering Cross Sections at Intermediate Energies

    CERN Document Server

    Albers, D; Bisplinghoff, J; Bollmann, R; Büsser, K; Busch, M; Daniel, R; Diehl, O; Dohrmann, F; Engelhardt, H P; Ernst, J; Eversheim, P D; Gasthuber, M; Gebel, R; Greiff, J; Gross, A; Gross-Hardt, R; Heider, S; Heine, A; Hinterberger, F; Hueskes, T; Igelbrink, M; Jeske, M; Langkau, R; Lindlein, J; Maier, R; Maschuw, R; Mosel, F; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Scheid, N; Schirm, N; Schulz-Rojahn, M; Schwandt, F; Schwarz, V; Scobel, W; Thomas, S; Trelle, H J; Weise, E; Wellinghausen, A; Woller, K; Ziegler, R

    2004-01-01

    We have measured differential cross sections for \\pp elastic scattering with internal fiber targets in the recirculating beam of the proton synchrotron COSY. Measurements were made continuously during acceleration for projectile kinetic energies between 0.23 and 2.59 GeV in the angular range $30 \\leq \\theta_{c.m.} \\leq 90$ deg. Details of the apparatus and the data analysis are given and the resulting excitation functions and angular distributions presented. The precision of each data point is typically better than 4%, and a relative normalization uncertainty of only 2.5% within an excitation function has been reached. The impact on phase shift analysis as well as upper bounds on possible resonant contributions in lower partial waves are discussed.

  6. Density effect of the neutron halo nucleus induced reactions in intermediate energy heavy ion collisions

    Institute of Scientific and Technical Information of China (English)

    CAO Xi-Guang; CHEN Jin-Gen; MA Yu-Gang; FANG De-Qing; TIAN Wen-Dong; YAN Ting-Zhi; CAI Xiang-Zhou

    2009-01-01

    Using an isospin-dependent quantum molecular dynamics (IQMD) model, we study the 15C induced reactions from 30-120 MeV/nucleon systematically. Here the valence neutron of 15C is assigned at both 1d5/2 and 2s1/2 states respectively in order to study the density effect of reaction mechanism. It is. believed that the existent neutron halo structure at the 2s1/2 state of 15C will affect the light particle emission evidently.In our calculation, the different density distributions of 15C at two states are calculated by relativistic mean field (RMF) model and introduced in the initiation of IQMD model, respectively. It is found that some observables such as emission fragmentation multiplicity, emission neutron/proton ratio and emission neutrons'kinetic energy spectrum are sensitive to the initial density distribution.

  7. Fragmentation cross sections at intermediate energies for hadrontherapy and space radiation protection

    Directory of Open Access Journals (Sweden)

    De Napoli M.

    2014-03-01

    Full Text Available Nuclear fragmentation studies, historically driven by the interest of the nuclear physicists, are nowadays the subject of great attention for the hadrontherapy and the space radiation protection communities. In both fields, fragmentation cross sections are needed to predict the effects of the ion nuclear interactions within the patient’s and the astronaut’s body. Indeed, the the Monte Carlo codes used in planning tumor treatments and space missions must be tuned and validated by experimental data. However, only a limited set of fragmentation cross sections are available in literature, especially at Fermi energies. Therefore we have studied the production of secondary fragments in the 12C+12C and 12C+ 197Au reactions at 62 AMeV. Some of the measured cross sections are presented in this work.

  8. Fragmentation cross sections at intermediate energies for hadrontherapy and space radiation protection

    Science.gov (United States)

    De Napoli, M.; Agodi, C.; Bondi, M.; Cappuzzello, F.; Carbone, D.; Cavallaro, M.; Cirrone, G. A. P.; Cuttone, G.; Nicolosi, D.; Pandola, L.; Raciti, G.; Romano, F.; Sardina, D.; Scuderi, V.; Tropea, S.

    2014-03-01

    Nuclear fragmentation studies, historically driven by the interest of the nuclear physicists, are nowadays the subject of great attention for the hadrontherapy and the space radiation protection communities. In both fields, fragmentation cross sections are needed to predict the effects of the ion nuclear interactions within the patient's and the astronaut's body. Indeed, the the Monte Carlo codes used in planning tumor treatments and space missions must be tuned and validated by experimental data. However, only a limited set of fragmentation cross sections are available in literature, especially at Fermi energies. Therefore we have studied the production of secondary fragments in the 12C+12C and 12C+ 197Au reactions at 62 AMeV. Some of the measured cross sections are presented in this work.

  9. Isospin dependence of collective flow in heavy-ion collisions at intermediate energies

    CERN Document Server

    Li, B A; Ko, C M; Yennello, S J; Li, Bao An

    1996-01-01

    Within the framework of an isospin-dependent Boltzmann-Uehling-Uhlen beck (BUU) model using initial proton and neutron densities calculated from the nonlinear relativistic mean-field (RMF) theory, we compare the strength of transverse collective flow in reactions ^{48}Ca+^{58}Fe and ^{48}Cr+^{58}Ni, which have the same mass number but different neutron/proton ratios. The neutron-rich system (^{48}Ca+^{58}Fe) is found to show significantly stronger negative deflection and consequently has a higher balance energy, especially in peripheral collisions. NOTE ADDED IN PROOF: The new phenomenon predicted in this work has just been confirmed by an experiment done by G.D. Westfall et al. using the NSCL/MSU radioactive beam facility and a spartan soccer. A paper by R. Pak et al. is submitted to PRL to report the experimental result.

  10. Photoproduction de Mesons sur le Nucleon aux Energies Intermediaire (in French) [Photoproduction of mesons on the nucleon at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Guidal, Michel [Univ. of Paris, Orsay (France)

    1996-12-13

    One object of this thesis is to propose a model taking account of low transfer reaction mechanisms for a series of photoproduction reactions on nucleons for photon energies ≳4 GeV. If our comprehension of processes with low transfers is correct, then extrapolating our model in the domain of large transfers and the comparison with data supplied will give us information on the domains in energy and transfers from which an interpretation of reactions in terms of the "soft" process ceases to be valid. In the domain of large transfers, only one approach in terms of "hard" process can then explain the data. We are interested in electromagnetic photoproduction reactions because the probe, firstly, interacts with the target via an exact and well known mechanism (described by the QED theory) and also eliminates the interaction phenomena in the initial state. No probe is as well known as the photon. The extraction of reaction mechanisms, amplitudes and coupling constants match is made easier than in the case of hadronic probes. The energy domain Eγ >4 GeV studied is particularly interesting because it is from this energy of incident photons that can be expected to achieve large enough pulse transfers to hope for emergence of hard processes and therefore see the cessation of validity of interpretation of hadron models. Also, resonance effects are minor and do not interfere with our interpretations. Experimentally, this area is widely unexplored and the new generation accelerators of a large duty cycle (CEBAF, MAMI, ESRF, ELF, ...) combined with 4π detectors will allow to precisely measure low cross sections reactions of a large transfer. We first study pion photoproduction reactions on nucleon because they are the most experimentally accessible reactions and many data of high energy and low transfers exist. This will require strong constraints on the model parameters of the numerous analyses performed previously. Then we'll move on to kaon photoproduction

  11. Fission neutron spectra measurements at LANSCE - status and plans

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Robert C [Los Alamos National Laboratory; Noda, Shusaku [Los Alamos National Laboratory; Nelson, Ronald O [Los Alamos National Laboratory; O' Donnell, John M [Los Alamos National Laboratory; Devlin, Matt [Los Alamos National Laboratory; Chatillon, Audrey [CEA-FRANCE; Granier, Thierry [CEA-FRANCE; Taieb, Julien [CEA-FRANCE; Laurent, Benoit [CEA-FRANCE; Belier, Gilbert [CEA-FRANCE; Becker, John A [LLNL; Wu, Ching - Yen [LLNL

    2009-01-01

    A program to measure fission neutron spectra from neutron-induced fission of actinides is underway at the Los Alamos Neutron Science Center (LANSCE) in a collaboration among the CEA laboratory at Bruyeres-le-Chatel, Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The spallation source of fast neutrons at LANSCE is used to provide incident neutron energies from less than 1 MeV to 100 MeV or higher. The fission events take place in a gas-ionization fission chamber, and the time of flight from the neutron source to that chamber gives the energy of the incident neutron. Outgoing neutrons are detected by an array of organic liquid scintillator neutron detectors, and their energies are deduced from the time of flight from the fission chamber to the neutron detector. Measurements have been made of the fission neutrons from fission of {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. The range of outgoing energies measured so far is from 1 MeV to approximately 8 MeV. These partial spectra and average fission neutron energies are compared with evaluated data and with models of fission neutron emission. Results to date will be presented and a discussion of uncertainties will be given in this presentation. Future plans are to make significant improvements in the fission chambers, neutron detectors, signal processing, data acquisition and the experimental environment to provide high fidelity data including mea urements of fission neutrons below 1 MeV and improvements in the data above 8 MeV.

  12. Chiral symmetry restoration in heavy-ion collisions at intermediate energies

    Science.gov (United States)

    Palmese, A.; Cassing, W.; Seifert, E.; Steinert, T.; Moreau, P.; Bratkovskaya, E. L.

    2016-10-01

    We study the effect of the chiral symmetry restoration (CSR) on heavy-ion collisions observables in the energy range √{sN N}=3 -20 GeV within the parton-hadron-string dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the nonlinear σ -ω model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations. For the pion-nucleon Σ term we adopt Σπ≈ 45 MeV, which corresponds to some world average. Our systematic studies show that chiral symmetry restoration plays a crucial role in the description of heavy-ion collisions at √{sN N}=3 -20 GeV, realizing an increase of the hadronic particle production in the strangeness sector with respect to the nonstrange one. We identify particle abundances and rapidity spectra to be suitable probes in order to extract information about CSR, while transverse mass spectra are less sensitive. Our results provide a microscopic explanation for the so-called horn structure in the excitation function of the K+/π+ ratio: The CSR in the hadronic phase produces the steep increase of this particle ratio up to √{sN N}≈7 GeV, while the drop at higher energies is associated to the appearance of a deconfined partonic medium. Furthermore, the appearance and disappearance of the horn-structure are investigated as functions of the system size and collision centrality. We close this work by an analysis of strangeness production in the (T ,μB ) plane (as extracted from the PHSD for central Au+Au collisions) and discuss the possibilities to identify a possible critical point in the phase diagram.

  13. Long-term residual radioactivity in an intermediate-energy proton linac

    CERN Document Server

    Blaha, J; Silari, M; Vollaire, J

    2014-01-01

    A new 160 MeV H−H− linear accelerator (LINAC4) is being installed at CERN to replace the present 50 MeV LINAC2 as proton injector of the PS Booster (PSB). During operation, the accelerator components will be activated by the beam itself and by the secondary radiation field. Detailed Monte Carlo simulations, for various beam energies and several decay times, were performed to predict the residual radioactivity in the main accelerator components and to estimate the residual dose rate inside the tunnel. The results of this study will facilitate future dismantling, handling and storage of the activated parts and consequently minimize the radiation dose to involved workers. The component activation was also compared with the exemption limits given in the current Swiss legislation and to the CERN design values, in order to make predictions for the future storage and disposal of radioactive waste. The airborne radioactivity induced by particles escaping the beam dump and the activation of the beam dump cooling w...

  14. Ternary fission yields of 241Pu(nth,f)

    Science.gov (United States)

    Köster, Ulli; Faust, Herbert; Fioni, Gabriele; Friedrichs, Thomas; Groß, Martin; Oberstedt, Stephan

    1998-10-01

    Ternary events in the thermal neutron induced fission of 241Pu were studied with the recoil separator LOHENGRIN at the Institut Laue Langevin in Grenoble. Yields and energy distributions could be determined for most isotopes of the elements hydrogen to oxygen. Also several heavier nuclei up to 30Mg could be observed. Yields were measured for 42 isotopes, for further 17 isotopes upper limits could be deduced. For the first time the halo nuclei 11Li and 14Be were found in neutron induced fission with yields of some 10-10 per fission. This is orders of magnitude lower than predicted by most of the ternary fission models.

  15. Negative Pion Induced Fission with Heavy Target Nuclei

    Institute of Scientific and Technical Information of China (English)

    G. Sher; Mukhtar A. Rana; S. Manzoor; M. I. Shahzad

    2011-01-01

    We investigate fission induced by negative pions in copper and bismuth targets using CR-39 dielectric track detectors. The target-detector assemblies in Air-geometric configuration were exposed at the AGS facility of Brookhaven National Laboratory, USA. The exposed detectors were chemically etched under appropriate etching conditions and scanned to collect data in the form of fission fragments tracks produced as a result of interaction of pions with the target nuclei. Using the track counts, the experimental fission cross sections for copper and bismuth have been measured at energies of 500, 672, 1068 and 1665 MeV and compared with the calculation using the Cascade-Exciton Model code (CEM95). The values of fission probability based on experimental fission cross-sections have been compared with the theoretically calculated values of fission probabilities obtained using the CEM95 code. Good agreement is observed between the measured and computed results.

  16. Modeling secondary particle tracks generated by intermediate- and low-energy protons in water with the Low-Energy Particle Track Simulation code

    Science.gov (United States)

    Verkhovtsev, Alexey; Traore, Ali; Muñoz, Antonio; Blanco, Francisco; García, Gustavo

    2017-01-01

    Using a recent extension of the Low-Energy Particle Track Simulation (LEPTS) Monte Carlo code, we model the slowing-down of heavy charged particles propagating in water, combined with an explicit molecular-level description of radiation effects due to the formation of secondary electrons, their propagation through the medium, and electron-induced molecular dissociations. As a case study, we consider the transport of protons with the initial energy of 1 MeV until their thermalization, so that we cover the energy range that contributes mainly to the energy deposition in the Bragg peak region. In order to include protons into the simulation procedure, a comprehensive dataset of integral and differential cross sections of elastic and inelastic scattering of intermediate- and low-energy protons from water molecules is created. Experimental and theoretical cross sections available in the literature are carefully examined, compared and verified. The ionization cross section by protons includes recent experimental measurements of the production of different charged fragments.

  17. Energy dependence of the prompt γ -ray emission from the (d,p) -induced fission of U*234 and Pu*240

    Energy Technology Data Exchange (ETDEWEB)

    Rose, S. J.; Zeiser, F.; Wilson, J. N.; Oberstedt, A.; Oberstedt, S.; Siem, S.; Tveten, G. M.; Bernstein, L. A.; Bleuel, D. L.; Brown, J. A.; Crespo Campo, L.; Giacoppo, F.; Görgen, A.; Guttormsen, M.; Hadyńska, K.; Hafreager, A.; Hagen, T. W.; Klintefjord, M.; Laplace, T. A.; Larsen, A. C.; Renstrøm, T.; Sahin, E.; Schmitt, C.; Tornyi, T. G.; Wiedeking, M.

    2017-07-01

    Prompt-fission γ rays are responsible for approximately 5% of the total energy released in fission, and therefore important to understand when modeling nuclear reactors. In this work we present prompt γ -ray emission characteristics in fission as a function of the nuclear excitation energy of the fissioning system. Emitted γ -ray spectra were measured, and γ -ray multiplicities and average and total γ energies per fission were determined for the 233 U ( d , p f ) reaction for excitation energies between 4.8 and 10 MeV, and for the 239 Pu ( d , p f ) reaction between 4.5 and 9 MeV. The spectral characteristics show no significant change as a function of excitation energy above the fission barrier, despite the fact that an extra ~ 5 MeV of energy is potentially available in the excited fragments for γ decay. The measured results are compared with model calculations made for prompt γ -ray emission with the fission model code gef. Further comparison with previously obtained results from thermal neutron induced fission is made to characterize possible differences arising from using the surrogate ( d , p ) reaction.

  18. Ionization Chamber for Prompt Fission Neutron Investigations

    OpenAIRE

    ZEYNALOV Sh.; ZEYNALOVA O. V.; Hambsch, Franz-Josef; Sedyshev, P.; SHVETSOV V.

    2014-01-01

    In this work we report recent achievements in design of twin back-to-back ionization chamber (TIC) for fission fragment (FF) mass and kinetic energy measurement. Correlated FF kinetic energies, their masses and the angle of FF in respect to the axes in 3D Cartesian coordinates can be determined from analysis of the heights and shapes of the pulses induced by the fission fragments on the anodes of TIC. Anodes of TIC were designed as consisting of isolated strips each having independent electro...

  19. V&V of MCNP 6.1.1 Beta Against Intermediate and High-Energy Experimental Data

    Energy Technology Data Exchange (ETDEWEB)

    Mashnik, Stepan G [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-09-08

    This report presents a set of validation and verification (V&V) MCNP 6.1.1 beta results calculated in parallel, with MPI, obtained using its event generators at intermediate and high-energies compared against various experimental data. It also contains several examples of results using the models at energies below 150 MeV, down to 10 MeV, where data libraries are normally used. This report can be considered as the forth part of a set of MCNP6 Testing Primers, after its first, LA-UR-11-05129, and second, LA-UR-11-05627, and third, LA-UR-26944, publications, but is devoted to V&V with the latest, 1.1 beta version of MCNP6. The MCNP6 test-problems discussed here are presented in the /VALIDATION_CEM/and/VALIDATION_LAQGSM/subdirectories in the MCNP6/Testing/directory. README files that contain short descriptions of every input file, the experiment, the quantity of interest that the experiment measures and its description in the MCNP6 output files, and the publication reference of that experiment are presented for every test problem. Templates for plotting the corresponding results with xmgrace as well as pdf files with figures representing the final results of our V&V efforts are presented. Several technical “bugs” in MCNP 6.1.1 beta were discovered during our current V&V of MCNP6 while running it in parallel with MPI using its event generators. These “bugs” are to be fixed in the following version of MCNP6. Our results show that MCNP 6.1.1 beta using its CEM03.03, LAQGSM03.03, Bertini, and INCL+ABLA, event generators describes, as a rule, reasonably well different intermediate- and high-energy measured data. This primer isn’t meant to be read from cover to cover. Readers may skip some sections and go directly to any test problem in which they are interested.

  20. Modelling the widths of fission observables in GEF

    Directory of Open Access Journals (Sweden)

    Schmidt K.-H.

    2013-03-01

    Full Text Available The widths of the mass distributions of the different fission channels are traced back to the probability distributions of the corresponding quantum oscillators that are coupled to the heat bath, which is formed by the intrinsic degrees of freedom of the fissioning system under the influence of pairing correlations and shell effects. Following conclusion from stochastic calculations of Adeev and Pashkevich, an early freezing due to dynamical effects is assumed. It is shown that the mass width of the fission channels in low-energy fission is strongly influenced by the zero-point motion of the corresponding quantum oscillator. The observed variation of the mass widths of the asymmetric fission channels with excitation energy is attributed to the energy-dependent properties of the heat bath and not to the population of excited states of the corresponding quantum oscillator.

  1. Applications of Event-by-Event Fission Modeling with FREYA

    Directory of Open Access Journals (Sweden)

    Vogt R.

    2012-02-01

    Full Text Available The recently developed code FREYA (Fission Reaction Event Yield Algorithm generates large samples of complete fission events, consisting of two receding product nuclei as well as a number of neutrons and photons, all with complete kinematic information. Thus it is possible to calculate arbitrary correlation observables whose behavior may provide unique insight into the fission process. We first discuss the present status of FREYA, which has now been extended to include spontaneous fission. Concentrating on 239Pu(nth,f, 240Pu(sf and 252Cf(sf, we discuss the neutron multiplicity correlations, the dependence of the neutron energy spectrum on the neutron multiplicity, and the relationship between the fragment kinetic energy and the number of neutrons and their energies. We also suggest novel fission observables that could be measured with modern detectors.

  2. Differential, elastic integral and moment transfer cross sections for electron scattering from N2 at intermediate- and high-energies

    Institute of Scientific and Technical Information of China (English)

    Shi De-Heng; Liu Yu-Fang; Sun Jin-Feng; Zhu Zun-Lue; Yang Xiang-Dong

    2005-01-01

    A complex optical model potential modified by incorporating the concept of bonded atom, with the overlapping effect of electron clouds between two atoms in a molecule taken into consideration, is firstly employed to calculate the differential cross sections, elastic integral cross sections, and moment transfer cross sections for electron scattering from molecular nitrogen over the energy range 300-1000eV by using additivity rule model at Hartree-Fock level. The bondedatom concept is used in the study of the complex optical model potential composed of static, exchange, correlation polarization and absorption contributions. The calculated quantitative molecular differential cross sections, elastic integral cross sections, and moment transfer cross sections are compared with the experimental and theoretical ones wherever available, and they are found to be in good agreement with each other. It is shown that the additivity rule model together with the complex optical model potential modified by incorporating the concept of bonded atom is completely suitable for the calculations of differential cross section, elastic integral cross section and moment transfer cross section over the intermediate- and high-energy ranges.

  3. Validation and Verification of MCNP6 Against Intermediate and High-Energy Experimental Data and Results by Other Codes

    CERN Document Server

    Mashnik, Stepan G

    2010-01-01

    MCNP6, the latest and most advanced LANL transport code representing a recent merger of MCNP5 and MCNPX, has been Validated and Verified (V&V) against a variety of intermediate and high-energy experimental data and against results by different versions of MCNPX and other codes. In the present work, we V&V MCNP6 using mainly the latest modifications of the Cascade-Exciton Model (CEM) and of the Los Alamos version of the Quark-Gluon String Model (LAQGSM) event generators CEM03.02 and LAQGSM03.03. We found that MCNP6 describes reasonably well various reactions induced by particles and nuclei at incident energies from 18 MeV to about 1 TeV per nucleon measured on thin and thick targets and agrees very well with similar results obtained with MCNPX and calculations by CEM03.02, LAQGSM03.01 (03.03), INCL4 + ABLA, and Bertini INC + Dresner evaporation, EPAX, ABRABLA, HIPSE, and AMD, used as stand alone codes. Most of several computational bugs and more serious physics problems observed in MCNP6/X during our V...

  4. Mapping the deformation in the "island of inversion": Inelastic scattering of 30Ne and 36Mg at intermediate energies

    Science.gov (United States)

    Doornenbal, P.; Scheit, H.; Takeuchi, S.; Aoi, N.; Li, K.; Matsushita, M.; Steppenbeck, D.; Wang, H.; Baba, H.; Ideguchi, E.; Kobayashi, N.; Kondo, Y.; Lee, J.; Michimasa, S.; Motobayashi, T.; Poves, A.; Sakurai, H.; Takechi, M.; Togano, Y.; Yoneda, K.

    2016-04-01

    The transition strengths of the first-excited 2+ states and deformation lengths of the nuclei 30Ne and 36Mg were determined via Coulomb- and nuclear-force-dominated inelastic scattering at intermediate energies. Beams of these exotic nuclei were produced at the RIKEN Radioactive Isotope Beam Factory and were incident on lead and carbon targets at energies above 200 MeV/u . Absolute excitation cross sections on the lead target yielded reduced transition probabilities of 0.0277(79) and 0.0528(121) e2b2 , while the measurements with the carbon target revealed nuclear deformation lengths of δN=1.98 (11) and 1.93(11) fm for 30Ne and 36Mg, respectively. Corresponding quadrupole deformation parameters of β2˜0.5 from the two probes were found comparable in magnitude, showing no indication for a reduction in deformation along isotopic and isotonic chains from 32Mg towards the neutron drip-line. Comparisons to shell-model calculations illustrate the importance of neutron excitations across the N =20 shell for 30Ne and suggest that shallow maximums of collectivity may occur around N =22 and 24 along the neon and magnesium isotopic chains, respectively.

  5. Photoproduction of mesons on the nucleon at intermediate energies; Photoproduction de mesons sur le nucleon aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Guidal, M

    1997-01-01

    In this work a model is proposed to simulate the photoproduction of pseudoscalar mesons ('PI' and K) on the nucleon at high energy. This model is based on the exchange of mesonic or baryonic Regge trajectories, it is gauge invariant and it uses a Feynman diagram formalism inspired from isobaric models. The measurements concerning the following reactions {gamma}p {yields} n{pi}{sup +}, {gamma}n {yields} p{pi}{sup -}, {gamma}p {yields} p{pi}{sup 0} and {gamma}n {yields} n{pi}{sup 0} are reviewed and the new model is confronted to the experimental results. The model gives a reasonable and coherent description of these 4 reactions. The model has also been applied to the photoproduction of strange mesons and of {lambda} and {sigma} baryons and has been extrapolated at low energy to the threshold of the reaction, the model matches the results even up to E{sub {gamma}} = 2 GeV for differential cross-sections and recoil polarization. An attempt has been made to associate a Regge based description, which is valid with low transfers, with perturbative quantum chromodynamics which is valid with high transfers. The model relies on the saturation of trajectories in the high transfer region and on the counting laws that give the right variation of the cross-section. It seems that a model based on linear trajectories can be reliable up to 4 GeV. The domain of high transfer has been too little investigated to provide enough experimental data to validate the model. An experiment whose purpose is to study the photoproduction of {phi} at high transfer, is proposed. This experiment requires an accelerator with high useful cycle because of the smallness of the expected cross-section. The CEBAF (continuous electron beam accelerator facility) as well as the CLAS 4{pi} detector is presented. The study of {gamma}p {yields} p{phi} and {gamma}p {yields} K{lambda}{sup *} (1520) requires the discrimination of kaons from pions so the measurement of 180 ps as time resolution allows the

  6. Fission barrier, damping of shell correction and neutron emission in the fission of A$\\sim$200

    CERN Document Server

    Mahata, K; Kapoor, S S

    2015-01-01

    Decay of $^{210}$Po compound nucleus formed in light and heavy-ion induced fusion reactions has been analyzed simultaneously using a consistent prescription for fission barrier and nuclear level density incorporating shell correction and its damping with excitation energy. Good description of all the excitation functions have been achieved with a fission barrier of 21.9 $\\pm$ 0.2 MeV. For this barrier height, the predicted statistical pre-fission neutrons in heavy-ion fusion-fission are much smaller than the experimental values, implying the presence of dynamical neutrons due to dissipation even at these low excitation energies ($\\sim$ 50~MeV) in the mass region A $\\sim$ 200. When only heavy-ion induced fission excitation functions and the pre-fission neutron multiplicities are included in the fits, the deduced best fit fission barrier depends on the assumed fission delay time during which dynamical neutrons can be emitted. A fission delay of (0.8 $\\pm$ 0.1 )$\\times 10^{-19}$ s has been estimated correspondin...

  7. True ternary fission

    Science.gov (United States)

    Vijayaraghavan, K. R.; Balasubramaniam, M.; von Oertzen, W.

    2015-04-01

    The study of the ternary fission of nuclei has received new interest recently. It is of general interest for nuclear dynamics, although the process is very rare. In the present work, we discuss the possibilities of true ternary fission (fragment masses A >30 ) in 252Cf for different mass splits. These mass splits are strongly favored in a collinear geometry. Based on the three cluster model (TCM), it is shown that the true ternary fission into fragments with almost equal masses is one of the possible fission modes in 252Cf . For general decays it is shown that the formation of the lightest fragment at the center has the highest probability. Further the formation of tin isotopes and/or other closed shell fragments are favored. For the decay products the presence of closed shell nuclei among the three fragments enhances the decay probabilities.

  8. Fission in a Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Younes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-26

    A three-year theory project was undertaken to study the fission process in extreme astrophysical environments, such as the crust of neutron stars. In the first part of the project, the effect of electron screening on the fission process was explored using a microscopic approach. For the first time, these calculations were carried out to the breaking point of the nucleus. In the second part of the project, the population of the fissioning nucleus was calculated within the same microscopic framework. These types of calculations are extremely computer-intensive and have seldom been applied to heavy deformed nuclei, such as fissioning actinides. The results, tools and methodologies produced in this work will be of interest to both the basic-science and nuclear-data communities.

  9. Continuous-Energy Adjoint Flux and Perturbation Calculation using the Iterated Fission Probability Method in Monte Carlo Code TRIPOLI-4® and Underlying Applications

    Science.gov (United States)

    Truchet, G.; Leconte, P.; Peneliau, Y.; Santamarina, A.; Malvagi, F.

    2014-06-01

    Pile-oscillation experiments are performed in the MINERVE reactor at the CEA Cadarache to improve nuclear data accuracy. In order to precisely calculate small reactivity variations (experiments, a reference calculation need to be achieved. This calculation may be accomplished using the continuous-energy Monte Carlo code TRIPOLI-4® by using the eigenvalue difference method. This "direct" method has shown limitations in the evaluation of very small reactivity effects because it needs to reach a very small variance associated to the reactivity in both states. To answer this problem, it has been decided to implement the exact perturbation theory in TRIPOLI-4® and, consequently, to calculate a continuous-energy adjoint flux. The Iterated Fission Probability (IFP) method was chosen because it has shown great results in some other Monte Carlo codes. The IFP method uses a forward calculation to compute the adjoint flux, and consequently, it does not rely on complex code modifications but on the physical definition of the adjoint flux as a phase-space neutron importance. In the first part of this paper, the IFP method implemented in TRIPOLI-4® is described. To illustrate the effciency of the method, several adjoint fluxes are calculated and compared with their equivalent obtained by the deterministic code APOLLO-2. The new implementation can calculate angular adjoint flux. In the second part, a procedure to carry out an exact perturbation calculation is described. A single cell benchmark has been used to test the accuracy of the method, compared with the "direct" estimation of the perturbation. Once again the method based on the IFP shows good agreement for a calculation time far more inferior to the "direct" method. The main advantage of the method is that the relative accuracy of the reactivity variation does not depend on the magnitude of the variation itself, which allows us to calculate very small reactivity perturbations with high precision. Other applications of

  10. Relative motion correction to fission barriers

    CERN Document Server

    Skalski, J

    2007-01-01

    We discuss the effect of kinetic energy of the relative motion becoming spurious for separate fragments on the selfconsistent mean-field fission barriers. The treatment of the relative motion in the cluster model is contrasted with the necessity of a simpler and approximate approach in the mean-field theory. A scheme of the energy correction to the Hartree-Fock is proposed. The results obtained with the effective Skyrme interaction SLy6 show that the correction, previously estimated as $\\sim$ 8 MeV in $A=70-100$ nuclei, amounts to 4 MeV in the medium heavy nucleus $^{198}$Hg and to null in $^{238}$U. However, the corrected barrier implies a shorter fission half-life of the latter nucleus. The same effect is expected to lower barriers for multipartition (i.e. ternary fission, etc) and make hyperdeformed minima less stable.

  11. Relative Motion Correction to Fission Barriers

    Science.gov (United States)

    Skalski, J.

    We discuss the effect of kinetic energy of the relative motion becoming spurious for separate fragments on the selfconsistent mean-field fission barriers. The treatment of the relative motion in the cluster model is contrasted with the necessity of a simpler and approximate approach in the mean-field theory. A scheme of the energy correction to the Hartree-Fock is proposed. The results obtained with the effective Skyrme interaction SLy6 show that the correction, previously estimated as ~ 8 MeV in A = 70 - 100 nuclei, amounts to 4 MeV in the medium heavy nucleus 198Hg and to null in 238U. However, the corrected barrier implies a shorter fission half-life of the latter nucleus. The same effect is expected to lower barriers for multipartition (i.e. ternary fission, etc) and make hyperdeformed minima less stable.

  12. Antiproton Induced Fission and Fragmentation of Nuclei

    CERN Multimedia

    2002-01-01

    The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...

  13. Safe and Cheap and Abundant and Clean Fission Energy Resource:Perfect and Feasible Gen-Ⅴ Molten-salt Depleted-uranium Reactor

    Institute of Scientific and Technical Information of China (English)

    DONG; Bao-guo; DONG; Pei; GU; Ji-yuan

    2015-01-01

    The supercritical,reactor core melting and nuclear fuel leaking accidents have troubled fission reactors for decades,and greatly limit their extensive applications.Now these troubles are still open.Here we first show a possible perfect reactor,Molten-salt Depleted-uranium Reactor

  14. Singlet Fission of Non-polycyclic Aromatic Molecules in Organic Photovoltaics.

    Science.gov (United States)

    Kawata, So; Pu, Yong-Jin; Saito, Ayaka; Kurashige, Yuki; Beppu, Teruo; Katagiri, Hiroshi; Hada, Masaki; Kido, Junji

    2016-02-24

    Singlet fission of thienoquinoid compounds in organic photovoltaics is demonstrated. The escalation of the thienoquinoid length of the compounds realizes a suitable packing structure and energy levels for singlet fission. The magnetic-field dependence of the photocurrent and the external quantum efficiency of the devices reveal singlet fission of the compounds and dissociation of triplet excitons into charges.

  15. Fission barriers and probabilities of spontaneous fission for elements with Z$\\geq$100

    CERN Document Server

    Baran, A; Reinhard, P -G; Robledo, L M; Staszczak, A; Warda, M

    2015-01-01

    This is a short review of methods and results of calculations of fission barriers and fission half-lives of even-even superheavy nuclei. An approvable agreement of the following approaches is shown and discussed: The macroscopic-microscopic approach based on the stratagem of the shell correction to the liquid drop model and a vantage point of microscopic energy density functionals of Skyrme and Gogny type selfconsistently calculated within Hartree-Fock-Bogoliubov method. Mass parameters are calculated in the Hartree-Fock-Bogoliubov cranking approximation. A short part of the paper is devoted to the nuclear fission dynamics. We also discuss the predictive power of Skyrme functionals applied to key properties of the fission path of $^{266}$Hs. It applies the standard techniques of error estimates in the framework of a $\\chi^2$ analysis.

  16. Improved Fission Neutron Data Base for Active Interrogation of Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

    2013-11-06

    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

  17. Spectroscopy of heavy fissionable nuclei

    Indian Academy of Sciences (India)

    S K Tandel

    2015-09-01

    Structural studies of heavy nuclei are quite challenging due to increased competition from fission, particularly at high spins. Nuclei in the actinide region exhibit a variety of interesting phenomena. Recent advances in instrumentation and analysis techniques have made feasible sensitive measurements of nuclei populated with quite low cross-sections. These include isomers and rotational band structures in isotopes of Pu ( = 94) to Rf ( = 104), and octupole correlations in the Th ( = 90) region. The obtained experimental data have provided insights on various aspects like moments of inertia and nucleon alignments at high spins, quasiparticle energies and evolution of quadrupole and octupole collectivity, among others. An overview of some of these results is presented.

  18. Dissipative effects in fission investigated in complete kinematics measurements

    Science.gov (United States)

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Taïeb, J.; Ramos, D.; Álvarez-Pol, H.; Audouin, L.; Ayyad, Y.; Bélier, G.; Boutoux, G.; Casarejos, E.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelić-Heil, A.; Laurent, B.; Martin, J.-F.; Paradela, C.; Pellereau, E.; Pietras, B.; Rodríguez-Tajes, C.; Rossi, D. M.; Simon, H.; Vargas, J.; Voss, B.

    2017-09-01

    The study of dissipative effects in fission has been carried out with fusion-fission reactions by using a limited number of observables, such as the fission probabilities, the mass distribution of the fission fragments, or the neutron multiplicities. However, the large angular momenta gained by the compound nucleus in this kind of reaction could affect the conclusions drawn from such experiments. In this work, we propose to investigate the fission dynamics by the use of spallation reactions on 208Pb because the fissioning systems are produced with low angular momentum, small deformations, and high excitation energies, enhancing the dissipative effects. The complete kinematics measurements of the fission fragments and light-charged particles were performed by the use of the SOFIA setup combined with the inverse kinematics technique, allowing us for the first time a full indentification in atomic and mass number of the two fission fragments. These measurements permit us to define new fission observables for the investigation of the temperature and deformation dependencies of the dissipation parameter.

  19. Fission neutron output measurements at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Ronald Owen [Los Alamos National Laboratory; Haight, Robert C [Los Alamos National Laboratory; Devlin, Matthew J [Los Alamos National Laboratory; Fotiadis, Nikolaos [Los Alamos National Laboratory; Laptev, Alexander [Los Alamos National Laboratory; O' Donnell, John M [Los Alamos National Laboratory; Taddeucci, Terry N [Los Alamos National Laboratory; Tovesson, Fredrik [Los Alamos National Laboratory; Ullmann, J L [Los Alamos National Laboratory; Wender, Stephen A [Los Alamos National Laboratory; Bredeweg, T A [Los Alamos National Laboratory; Jandel, M [Los Alamos National Laboratory; Vieira, D J [Los Alamos National Laboratory; Wu, Ching - Yen [LLNL; Becker, J A [LLNL; Stoyer, M A [LLNL; Henderson, R [LLNL; Sutton, M [LLNL; Belier, Gilbert [BRUYERES-LE-CHATEL, FRANCE; Chatillon, A [BRUYERES-LE-CHATEL, FRANCE; Granier, Thierry [CEA, BRUYERES-LE-CHATEL, FRANCE; Laurent, Benoit [CEA, BRUYERES-LE-CHATEL, FRANCE; Taieb, Julien [CEA, BRUYERES-LE-CHATEL, FRANCE

    2010-01-01

    Accurate data for both physical properties and fission properties of materials are necessary to properly model dynamic fissioning systems. To address the need for accurate data on fission neutron energy spectra, especially at outgoing neutron energies below about 200 keV and at energies above 8 MeV, ongoing work at LANSCE involving collaborators from LANL, LLNL and CEA Bruyeres-le-Chatel is extending the energy range, efficiency and accuracy beyond previous measurements. Initial work in the outgoing neutron energy range from 1 to 7 MeV is consistent with current evaluations and provides a foundation for extended measurements. As part of these efforts, a new fission fragment detector that reduces backgrounds and improves timing has been designed fabricated and tested, and new neutron detectors are being assessed for optimal characteristics. Simulations of experimental designs are in progress to ensure that accuracy goals are met. Results of these measurements will be incorporated into evaluations and data libraries as they become available.

  20. ISOLDE experiment explores new territory in nuclear fission

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    An international collaboration led by the University of Leuven, Belgium, exploiting ISOLDE’s radioactive beams, has recently discovered an unexpected new type of asymmetric nuclear fission, which challenges current theories. The surprising result opens the way for new nuclear structure models and further theories to elucidate the question.   Resonance Ionization Laser Ion Source (RILIS) in action at ISOLDE. RILIS was instrumental in providing the pure beam necessary for the successful nuclear fission experiment. In nuclear fission, the nucleus splits into two fragments (daughter nuclei), releasing a huge amount of energy. Nuclear fission is exploited in power plants to produce energy. From the fundamental research point of view, fission is not yet fully understood decades after its discovery and its properties can still surprise nuclear physicists. The way the process occurs can tell us a lot about the internal structure of the nucleus and the interactions taking place inside the com...