WorldWideScience

Sample records for proton capture nucleosynthesis

  1. p-process nucleosynthesis via proton-capture reactions in thermonuclear supernovae explosions

    Directory of Open Access Journals (Sweden)

    Endres Anne

    2015-01-01

    Full Text Available Model calculations within the framework of the so-called γ process show an underproduction of the p nucleus with the highest isotopic abundace 92Mo. This discrepancy can be narrowed by taking into account the alternative production site of a type Ia supernova explosion. Here, the nucleus 92Mo can be produced by a sequence of proton-capture reactions. The amount of 92Mo nuclei produced via this reaction chain is most sensitive to the reactions 90Zr(p,γ and 91Nb(p,γ. Both rates have to be investigated experimentally to study the impact of this nucleosynthesis aspect on the long-standing 92Mo-problem. We have already measured the proton-capture reaction on 90Zr using high-resolution in-beam γ-ray spectroscopy. In this contribution, we will present our preliminary results of the total cross sections as well as the partial cross sections. Furthermore, we plan to measure the 91Nb(p,γ reaction soon. Due to the radioactive target material, the 91Nb nuclei have to be produced prior to the experiment. The current status of this production will be presented in this contribution.

  2. Radiative neutron capture on a proton at big-bang nucleosynthesis energies

    International Nuclear Information System (INIS)

    Ando, S.; Cyburt, R. H.; Hong, S. W.; Hyun, C. H.

    2006-01-01

    The total cross section for radiative neutron capture on a proton, np→dγ, is evaluated at big-bang nucleosynthesis (BBN) energies. The electromagnetic transition amplitudes are calculated up to next-to-leading-order within the framework of pionless effective field theory with dibaryon fields. We also calculate the dγ→np cross section and the photon analyzing power for the dγ(vector sign)→np process from the amplitudes. The values of low-energy constants that appear in the amplitudes are estimated by a Markov Chain Monte Carlo analysis using the relevant low-energy experimental data. Our result agrees well with those of other theoretical calculations except for the np→dγ cross section at some energies estimated by an R-matrix analysis. We also study the uncertainties in our estimation of the np→dγ cross section at relevant BBN energies and find that the estimated cross section is reliable to within ∼1% error

  3. Implication of the Proton-Deuteron Radiative Capture for Big Bang Nucleosynthesis.

    Science.gov (United States)

    Marcucci, L E; Mangano, G; Kievsky, A; Viviani, M

    2016-03-11

    The astrophysical S factor for the radiative capture d(p,γ)^{3}He in the energy range of interest for big bang nucleosynthesis (BBN) is calculated using an ab initio approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions-the Argonne v_{18} and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the 1/m leading order contribution (m is the nucleon mass), also the next-to-leading order term, proportional to 1/m^{3}. The many-body currents are constructed in order to satisfy the current conservation relation with the adopted Hamiltonian model. The hyperspherical harmonics technique is applied to solve the A=3 bound and scattering states. Particular attention is paid in this second case in order to obtain, in the energy range of BBN, an uncertainty on the astrophysical S factor of the order or below ∼1%. Then, in this energy range, the S factor is found to be ∼10% larger than the currently adopted values. Part of this increase (1%-3%) is due to the 1/m^{3} one-body operator, while the remaining is due to the new more accurate scattering wave functions. We have studied the implication of this new determination for the d(p,γ)^{3}He S factor on the deuterium primordial abundance. We find that the predicted theoretical value for ^{2}H/H is in excellent agreement with its experimental determination, using the most recent determination of the baryon density of the Planck experiment, and with a standard number of relativistic degrees of freedom N_{eff}=3.046 during primordial nucleosynthesis. This calls for a more accurate measurement of the astrophysical S factor in order to confirm the present predictions.

  4. Electron Capture Cross Sections for Stellar Nucleosynthesis

    Directory of Open Access Journals (Sweden)

    P. G. Giannaka

    2015-01-01

    Full Text Available In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasiparticle random-phase approximation (pn-QRPA and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the abovementioned e--capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the 66Zn isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

  5. Capture reactions on C-14 in nonstandard big bang nucleosynthesis

    Science.gov (United States)

    Wiescher, Michael; Gorres, Joachim; Thielemann, Friedrich-Karl

    1990-01-01

    Nonstandard big bang nucleosynthesis leads to the production of C-14. The further reaction path depends on the depletion of C-14 by either photon, alpha, or neutron capture reactions. The nucleus C-14 is of particular importance in these scenarios because it forms a bottleneck for the production of heavier nuclei A greater than 14. The reaction rates of all three capture reactions at big bang conditions are discussed, and it is shown that the resulting reaction path, leading to the production of heavier elements, is dominated by the (p, gamma) and (n, gamma) rates, contrary to earlier suggestions.

  6. Neutron-capture nucleosynthesis in the first stars

    International Nuclear Information System (INIS)

    Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Sneden, Christopher

    2014-01-01

    Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars.

  7. Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis

    Science.gov (United States)

    Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu

    Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.

  8. Neutron-capture Nucleosynthesis in the First Stars

    Science.gov (United States)

    Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Sneden, Christopher

    2014-04-01

    Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, and The McDonald Observatory of The University of Texas at Austin.

  9. Proton capture resonance studies

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, G.E. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Bilpuch, E.G. [Duke University, Durham, North Carolina (United States) 27708]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Bybee, C.R. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Cox, J.M.; Fittje, L.M. [Tennessee Technological University, Cookeville, Tennessee (United States) 38505]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Labonte, M.A.; Moore, E.F.; Shriner, J.D. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Shriner, J.F. Jr. [Tennessee Technological University, Cookeville, Tennessee (United States) 38505]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Vavrina, G.A. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Wallace, P.M. [Duke University, Durham, North Carolina (United States) 27708]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708

    1997-02-01

    The fluctuation properties of quantum systems now are used as a signature of quantum chaos. The analyses require data of extremely high quality. The {sup 29}Si(p,{gamma}) reaction is being used to establish a complete level scheme of {sup 30}P to study chaos and isospin breaking in this nuclide. Determination of the angular momentum J, the parity {pi}, and the isospin T from resonance capture data is considered. Special emphasis is placed on the capture angular distributions and on a geometric description of these angular distributions. {copyright} {ital 1997 American Institute of Physics.}

  10. Proton capture by magnetic monopoles

    International Nuclear Information System (INIS)

    Olaussen, K.; Olsen, H.A.; Oeverboe, I.; Osland, P.

    1983-09-01

    In the Kazama-Yang approximation, the lowest monopole-proton bound states have binding energies of 938 MeV, 263 keV, 105 eV, and 0.04 eV. The cross section for radiative capture to these states is for velocities β = 10 -5 - 10 -3 found to be of the order of 10 -28 - 10 -26 cm 2 . For the state that has a binding energy of 263 keV, the capture length in water is 171 x (β/10 -4 )sup(0.48) m. Observation of photons from the capture process would indicate the presence of monopoles. (orig.)

  11. Astrophysical neutron capture rates in s- and r-process nucleosynthesis

    International Nuclear Information System (INIS)

    Beer, H.; Mohr, P.; Oberhummer, H.; Rauscher, T.; Mutti, P.; Corvi, F.; Sedyshev, P.V.; Popov, Yu.P.

    1997-01-01

    The astrophysical neutron capture rates of light and heavy nuclei are measured and calculated. The measurements are realized using the activation technique at the 3.75 MV Karlsruhe Van de Graaff accelerator and by means of the time-of-flight method at the Geel electron linear accelerator (GELINA). The setup for the fast cyclic activation measurements made on 26 Mg and 48 Ca, as well as on Pt isotopes is described. The time-of-flight method is used for neutron capture measurements of the bottleneck isotopes 138 Ba and 208 Pb. The calculations are made using direct and compound nuclear capture models. The s-process nucleosynthesis path in the Os and Pt mass region is discussed in details. It is shown that for 19 '1 Os, 192 Ir and 193 Pt there is a competition between β-decay and neutron capture. The β-decay half-lives are dependent on temperature and electron density of the s-process environment. The abundance of s-only 192 Pt originates from the branching at 191 Os and 192 Ir. The isotopes 190 Pt and 198 Pt are not on the s-process path, therefore the seed abundance vanish during nucleosynthesis. Calculations are carried out using parametrized models in order to reproduce the s-process abundance in the mass region from Os up to Pt. The neutron density is adjusted to reproduce the solar abundance of the s-only isotope 9 2 Pt in the analysis of the present branching especially

  12. Neutron Capture Cross Section of Unstable Ni63: Implications for Stellar Nucleosynthesis

    Science.gov (United States)

    Lederer, C.; Massimi, C.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Duran, I.; Dressler, R.; Dzysiuk, N.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Gurusamy, P.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Korschinek, G.; Krtička, M.; Kroll, J.; Langer, C.; Leeb, H.; Leong, L. S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Mastinu, P. F.; Mastromarco, M.; Meaze, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondelaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Pignatari, M.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Roman, F.; Rubbia, C.; Sarmento, R.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T. J.; Žugec, P.

    2013-01-01

    The Ni63(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from kT=5-100keV with uncertainties around 20%. Stellar model calculations for a 25M⊙ star show that the new data have a significant effect on the s-process production of Cu63, Ni64, and Zn64 in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

  13. Neutron-Capture Nucleosynthesis and the Chemical Evolution of Globular Clusters

    Science.gov (United States)

    Shingles, Luke J.

    2015-09-01

    Elements heavier than iron are almost entirely produced in stars through neutron captures and radioactive decays. Of these heavy elements, roughly half are produced by the slow neutron-capture process (s-process), which takes place under extended exposure to low neutron densities. Most of the s-process production occurs in stars with initial masses between roughly 0.8 and 8 solar masses (Msun), which evolve through the Asymptotic Giant Branch (AGB) phase. This thesis explores several topics related to AGB stars and the s-process, with a focus on comparing theoretical models to observations in the literature on planetary nebulae, post-AGB stars, and globular cluster stars. A recurring theme is the uncertainty of carbon-13-pocket formation, which is crucial for building accurate models of s-process nucleosynthesis. We first investigated whether neutron-capture reactions in AGB stars are the cause of the low sulphur abundances in planetary nebulae and post-AGB stars relative to the interstellar medium. Accounting for uncertainties in the size of the partial mixing zone that forms carbon-13 pockets and the rates of neutron-capture and neutron-producing reactions, our models failed to reproduce the observed levels of sulphur destruction. From this, we concluded that AGB nucleosynthesis is not the cause of the sulphur anomaly. We also discovered a new method to constrain the extent of the partial mixing zone using neon abundances in planetary nebulae. We next aimed to discover the stellar sites of the s-process enrichment in globular clusters that have inter- and intra-cluster variation, with the examples of M4 (relative to M5) and M22, respectively. Using a new chemical evolution code developed by the candidate, we tested models with stellar yields from rotating massive stars and AGB stars. We compared our model predictions for the production of s-process elements with abundances from s-poor and s-rich populations. We found that rotating massive stars alone do not

  14. Dynamics of RF captured cooled proton beams

    International Nuclear Information System (INIS)

    Kells, W.; Mills, F.

    1983-01-01

    In the course of electron cooling experiments at the Electron Cooling Ring (ECR) at Fermilab, several peculiar features of the longitudinal phase space of cold protons (200 MeV) captured in RF buckets were observed. Here we present the experimental facts, present a simple theory, and summarize computer simulation results which support the theory and facts

  15. Neutron capture measurements on 62Ni, 63Ni and 197Au and their relevance for stellar nucleosynthesis

    CERN Document Server

    Lederer, Claudia

    Neutron capture reactions in stars are responsible for forming about 99% of the elemental abundances heavier than Fe. Two processes contribute about equally to the overall abundance pattern: the slow neutron capture process (s process) where neutron densities are small and therefore radioactive decay is generally faster than subsequent neutron capture on radionuclides, and the rapid neutron capture process (r process) which takes place in environments of high neutron densities, driving the reaction path towards the neutron rich side. The key nuclear physics input for s process studies are stellar neutron capture cross sections, called MACS (Maxwellian-averaged cross section). In the course of this work, dierent reactions relevant to s process nucleosynthesis have been studied. To improve and check existing information, neutron capture cross sections of most stable Fe and Ni isotopes were measured via the time-of-flight technique at the n TOF facility at CERN. This campaign was triggered by a work of Sneden et...

  16. Some effects of high temperature and density on neutron-capture nucleosynthesis

    International Nuclear Information System (INIS)

    Norman, E.B.; Kellogg, S.E.

    1984-01-01

    Examples of nuclear reactions between nuclei in excited states, beta decays of nuclear excited states, and bound-state beta decays are shown. The effects of these processes on selected problems in heavy-element nucleosynthesis are discussed. 40 references

  17. Electron Capture in Proton Collisions with CO.

    Science.gov (United States)

    Stancil, P. C.; Schultz, D. R.; Kimura, M.; Gu, J.-P.; Hirsch, G.; Buenker, R. J.; Li, Y.

    1999-10-01

    Electron capture by protons following collisions with carbon monoxide is studied with a variety of theoretical approaches including quantal and semiclassical molecular-orbital close-coupling (MOCC) and classical trajectory Monte Carlo (CTMC) techniques. The MOCC treatments utilize potential surfaces and couplings computed for a range of H^+-CO orientation angles and C-O separations. Results including integral, differential, electronic state-selective, and vibrational state-selective cross sections will be presented for low- to intermediate-energies. Comparison with experiment will be made where possible and the relevance of the reaction in astrophysics and atmospheric physics will be discussed.

  18. Capture of polarized deuterons on protons

    International Nuclear Information System (INIS)

    Fonseca, A.C.; Lehman, D.R.

    1995-01-01

    Full three-body calculations for the cross sections, vector analyzing powers, and tensor analyzing powers for radiative capture of polarized deuterons on protons over the energy range of available data are completed. The Paris, Bonn A, and AV14 two-nucleon interactions are used by means of separable-expansion methods. The Paris and Bonn interactions are handled by the Ernst-Shakin-Thaler (EST) method, whereas the AV14 potential is used through the new expansion of Koike, in order to reduce the two-variable integral equations to a single variable. The electromagnetic transition is calculated with the Siegert long-wavelength E1 operator. Comparisons are made between results for different nucleon-nucleon interactions and with respect to the experimental data. copyright 1995 American Institute of Physics

  19. Proton capture reactions and nuclear structure

    International Nuclear Information System (INIS)

    Kikstra, S.W.

    1989-01-01

    Experimental studies are described of the structure of 40 Ca and 42 Sc with measurements at proton-capture of (p, gamma) reactions. Where possible, an attempt has been made to interpret the results of the measurements in termsof existing models. The 40 Ca and 42 Sc nuclides were excited by bombarding 39 K and 41 Ca targets, respectively with low energy protons (E p = 0.3-3.0 MeV), that were produced by the Utrecht 3MV van de Graaff accelerator. From the measured energy and intensity of the gamma-rays created in the subsequent decay of the cuclei, information was obtained on the existence and properties of their excited states. In addition properties of two T = 3/2 levels at high excitation energy of the 9 Be nucleus were investigated. These levels were excited by the resonant absorption of gamma-rays from the 11 B(p, gamma) 12 C reaction. The results of the measurements are interpreted by a comparison to the analoque β-decay of 9 Li and to shell model calculations. The total decay energy of the superallowed O + → O + transition between the ground states of 42 Sc and 42 Ca was determined by measurements in Utrecht of the proton separation energy S p of 42 Sc and in Oak Ridge of S n of 42 Sc and 42 Ca. The results were used for verification of the conserved vector current hypothesis, which implies that the ft values of all superallowed O + → O + β-decays are the same. An attempt was made to describe properties of odd-parity states of A = 37-41 nuclei with a variant of the Warburton, Becker, Millener and Brown (WBMB) interaction.Finally a new method for the assignment of nuclear spins by a simple statistical analysis of spectroscopic information is proposed. (author). 169 refs.; 22 figs.; 24 schemes; 29 tabs

  20. Introduction to nucleosynthesis

    International Nuclear Information System (INIS)

    Guasp, J.

    1975-01-01

    After a short introduction on stellar evolution, the physical foundations of nucleosynthesis are exposed: H, He, C and O fusion, Si burning and the equilibrium process. The effect of neutrinos in the last stages of stellar evolution and Supernova explosions are treated too. Afterwards the neutron capture process, fast and slow, are considerated concluding with cosmic nucleogenesis and nucleosynthesis in overmasive objects. (author)

  1. New neutron capture and total cross section measurements on 88Sr and their impact on s-process nucleosynthesis

    International Nuclear Information System (INIS)

    Koehler, P.E.; Spencer, R.R.; Guber, K.H.

    1998-01-01

    The authors have made new and improved measurements of the neutron capture and total cross sections of 88 Sr at the Oak Ridge Electron Linear Accelerator (ORELA). Improvements over previous measurements include a wider incident neutron energy range, the use of metallic rather than carbonate samples, better background subtraction, reduced sensitivity to sample-dependent backgrounds, and better pulse-height weighting functions. Because of its small cross section, the 88 Sr(n,γ) reaction is an important bottleneck during the s-process nucleosynthesis. Hence, an accurate determination of this rate is needed to better constrain the neutron exposure in s-process models and to more fully exploit the recently discovered isotopic anomalies in certain meteorites. They describe the experimental procedures, compare the results to previous data, and discuss their astrophysical impact

  2. Nucleosynthesis at the proton drip line--a challenge for nuclear physics

    International Nuclear Information System (INIS)

    Schatz, H.; Goerres, J.; Wiescher, M.; Bildsten, L.; Rauscher, T.; Thielemann, F.-K.

    1998-01-01

    The rp-process in X-ray bursts is investigated using a complete and updated nuclear reaction network from H to Sn that is coupled to a one dimensional, one zone X-ray burst model. In particular we consider 2p-capture reactions that can bridge proton unbound nuclei and therefore accelerate the reaction flow. This allows for the first time the calculation of the actual endpoint of the rp-process. We find that for a 25 s burst the reaction flow reaches already Cd. The consequences for energy production, final composition of the ashes and fuel consumption are discussed. In addition, the influence of the current uncertainties in the nuclear physics data base on the results is investigated and the parameters for which a future experimental determination is most desirable are identified

  3. Near-Ultraviolet Observations of CS 29497-030: New Constraints on Neutron-Capture Nucleosynthesis Processes

    Science.gov (United States)

    Ivans, Inese I.; Sneden, Christopher; Gallino, Roberto; Cowan, John J.; Preston, George W.

    2005-07-01

    Employing spectra obtained with the new Keck I HIRES near-UV-sensitive detector, we have performed a comprehensive chemical composition analysis of the binary blue metal-poor star CS 29497-030. Abundances for 29 elements and upper limits for an additional seven have been derived, concentrating on elements largely produced by means of neutron-capture nucleosynthesis. Included in our analysis are the two elements that define the termination point of the slow neutron-capture process, lead and bismuth. We determine an extremely high value of [Pb/Fe]=+3.65+/-0.07 (σ=0.13) from three features, supporting the single-feature result obtained in previous studies. We detect Bi for the first time in a metal-poor star. Our derived Bi/Pb ratio is in accord with those predicted from the most recent FRANEC calculations of the slow neutron-capture process in low-mass asymptotic giant branch (AGB) stars. We find that the neutron-capture elemental abundances of CS 29497-030 are best explained by an AGB model that also includes very significant amounts of pre-enrichment of rapid neutron-capture process material in the protostellar cloud out of which the CS 29497-030 binary system formed. Mass transfer is consistent with the observed [Nb/Zr]~0. Thus, CS 29497-030 is both an r+s and ``extrinsic AGB'' star. Furthermore, we find that the mass of the AGB model can be further constrained by the abundance of the light odd-element Na. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  4. Impact of Neutrino Flavor Oscillations on the Neutrino-driven Wind Nucleosynthesis of an Electron-capture Supernova

    Science.gov (United States)

    Pllumbi, Else; Tamborra, Irene; Wanajo, Shinya; Janka, Hans-Thomas; Hüdepohl, Lorenz

    2015-08-01

    Neutrino oscillations, especially to light sterile states, can affect nucleosynthesis yields because of their possible feedback effect on the electron fraction (Ye). For the first time, we perform nucleosynthesis calculations for neutrino-driven wind trajectories from the neutrino-cooling phase of an 8.8 {M}⊙ electron-capture supernova (SN), whose hydrodynamic evolution was computed in spherical symmetry with sophisticated neutrino transport and whose Ye evolution was post-processed by including neutrino oscillations between both active and active-sterile flavors. We also take into account the α-effect as well as weak magnetism and recoil corrections in the neutrino absorption and emission processes. We observe effects on the Ye evolution that depend in a subtle way on the relative radial positions of the sterile Mikheyev-Smirnov-Wolfenstein resonances, on collective flavor transformations, and on the formation of α particles. For the adopted SN progenitor, we find that neutrino oscillations, also to a sterile state with eV mass, do not significantly affect the element formation and in particular cannot make the post-explosion wind outflow neutron-rich enough to activate a strong r-process. Our conclusions become even more robust when, in order to mimic equation-of-state-dependent corrections due to nucleon potential effects in the dense-medium neutrino opacities, six cases with reduced Ye in the wind are considered. In these cases, despite the conversion of active neutrinos to sterile neutrinos, Ye increases or is not significantly lowered compared to the values obtained without oscillations and active flavor transformations. This is a consequence of a complicated interplay between sterile-neutrino production, neutrino-neutrino interactions, and α-effect.

  5. Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ)69Ni

    Science.gov (United States)

    Spyrou, A.; Larsen, A. C.; Liddick, S. N.; Naqvi, F.; Crider, B. P.; Dombos, A. C.; Guttormsen, M.; Bleuel, D. L.; Couture, A.; Crespo Campo, L.; Lewis, R.; Mosby, S.; Mumpower, M. R.; Perdikakis, G.; Prokop, C. J.; Quinn, S. J.; Renstrøm, T.; Siem, S.; Surman, R.

    2017-04-01

    Neutron-capture reactions play an important role in heavy element nucleosynthesis, since they are the driving force for the two processes that create the vast majority of the heavy elements. When a neutron capture occurs on a short-lived nucleus, it is extremely challenging to study the reaction directly and therefore the use of indirect techniques is essential. The present work reports on such an indirect measurement that provides strong constraints on the 68Ni(n, γ)69Ni reaction rate. This is done by populating the compound nucleus 69Ni via the β decay of 69Co and measuring the γ-ray deexcitation of excited states in 69Ni. The β-Oslo method was used to extract the γ-ray strength function and the nuclear level density. In addition the half-life of 69Co was extracted and found to be in agreement with previous literature values. Before the present results, the 68Ni(n, γ)69Ni reaction was unconstrained and the purely theoretical reaction rate was highly uncertain. The new uncertainty on the reaction rate based on the present experiment (variation between upper and lower limit) is approximately a factor of 3. The commonly used reaction libraries JINA-REACLIB and BRUSLIB are in relatively good agreement with the experimental rate. The impact of the new rate on weak r-process calculations is discussed.

  6. Impact of neutrino flavor oscillations on the neutrino-driven wind nucleosynthesis of an electron-capture supernova

    NARCIS (Netherlands)

    Pllumbi, E.; Tamborra, I.; Wanajo, S.; Janka, H.-T.; Hüdepohl, L.

    2015-01-01

    Neutrino oscillations, especially to light sterile states, can affect nucleosynthesis yields because of their possible feedback effect on the electron fraction (Ye). For the first time, we perform nucleosynthesis calculations for neutrino-driven wind trajectories from the neutrino-cooling phase of

  7. Simulation of proton RF capture in the AGS Booster

    International Nuclear Information System (INIS)

    Khiari, F.Z.; Luccio, A.U.; Weng, W.T.

    1988-01-01

    RF capture of the proton beam in the AGS Booster has been simulated with the longitudinal phase-space tracking code ESME. Results show that a capture in excess of 95% can be achieved with multiturn injection of a chopped beam

  8. Neutron capture cross section of /sup 197/Au: A standard for stellar nucleosynthesis

    International Nuclear Information System (INIS)

    Ratynski, W.; Kaeppeler, F.

    1988-01-01

    We have measured the neutron capture cross section of gold using the 7 Li(p,n) 7 Be reaction for neutron production. This reaction not only provides the integrated neutron flux via the 7 Be activity of the target, but also allows for the simulation of a Maxwellian neutron energy spectrum at kT = 25 keV. As this spectrum is emitted in a forward cone of 120 0 opening angle, the cross section can be measured in good geometry and independent of any other standard. Systematic uncertainties were studied experimentally in a series of activations. The final stellar cross section at kT = 25 keV was found to be 648 +- 10 mb, and extrapolation to the common s-process temperature kT = 30 keV yields 582 +- 9 mb. This result is used for renormalization of a number of cross sections which had been measured relative to gold

  9. Nuclear structure near the particle drip-lines and explosive nucleosynthesis processes

    International Nuclear Information System (INIS)

    Kratz, K.L.; Pfeiffer, B.; Moeller, P.; Thielemann, F.K.; Wiescher, M.

    1999-01-01

    In this paper, we discuss the nuclear physics input for a selected set of explosive nucleosynthesis scenarios leading to rapid proton-- and neutron--capture processes. Observables (like e.g. luminosity curves or elemental abundance distributions) witness the interplay between nuclear structure aspects near the particle drip-lines and the appropriate astrophysical environments, and can give guidance to and constraints on stellar conditions and the associated nucleosynthesis. (authors)

  10. Radiative muon capture on nuclei and protons

    International Nuclear Information System (INIS)

    Azuelos, G.; Gorringe, T.P.; Henderson, R.; Macdonald, J.A.; Poutissou, J.M.; Azuelos, G.; Depommier, P.; Poutissou, R.; Ahmad, S.; Burnham, A.; Hasinoff, M.D.; Larabee, A.J.; Waltham, C.E.; Wright, D.H.; Armstrong, D.S.; Blecher, M.; Serna-Angel, A.; Bertl, W.; Chen, C.Q.; Zhang, N.S.; McDonald, S.C.; Taylor, G.N.; Robertson, B.C.

    1990-01-01

    A brief review is made of the study of gp, the induced pseudoscalar coupling constant, in radiative muon capture on light nuclei, and of motivations for a measurement on hydrogen, with particular emphasis on recent and ongoing experiments at TRIUMF [fr

  11. Experimental approach to explosive nucleosynthesis

    International Nuclear Information System (INIS)

    Kubono, S.

    1991-07-01

    Recent development of experimental studies on explosive nucleosynthesis, especially the rapid proton process and the primordial nucleosynthesis were discussed with a stress on unstable nuclei. New development in the experimental methods for the nuclear astrophysics is also discussed which use unstable nuclear beams. (author)

  12. Nucleosynthesis of proton-rich nuclei. Experimental results on the rp-process

    International Nuclear Information System (INIS)

    Galaviz, D; Amthor, A M; Bazin, D; Becerril, A D; Brown, B A; Cole, A; Cook, J M; Elliot, T; Estrade, A; Gade, A; Glasmacher, T; Lorusso, G; Matos, M; Montes, F; Mueller, W; Chen, A A; Fueloep, Z S; Heger, A; Howard, M E; Kessler, R

    2010-01-01

    We report in this study the nuclear properties of proton-rich isotopes located along the rp-process path. The experiments have recently been performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The level properties above the proton separation energy of the nuclei 30 S, 36 K and 37 Ca were measured with precision of < 10 keV. This will allow a reduction in the determination of the astrophysical (p,γ) reaction rate under rp-process conditions.

  13. Proton capture and loss in ion-molecule collisions

    International Nuclear Information System (INIS)

    Ibanez, S; Alessi, M; Zimmerman, V; Fregenal, D; Focke, P; Bernardi, G; Suarez, S

    2007-01-01

    We have measured proton distributions from the collision systems Ar + , Kr + on CH 4 molecular targets, searching for atom capture into the projectile continuum. Within the studied energy range (100 to 300 eV/u) we have not distinctive evidence of capture. A small contamination of ion beams with molecular ions as ArH + or KrH + , have shown to be enough to produce peak shaped structures at the projectile velocity. We, therefore, concentrate our study on proton loss from molecular ions in collision with several targets

  14. Primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Gustavino, C.; Anders, M.; Bemmerer, D.; Elekes, Z.; Trezzi, D.

    2016-01-01

    Big Bang nucleosynthesis (BBN) describes the production of light nuclei in the early phases of the Universe. For this, precise knowledge of the cosmological parameters, such as the baryon density, as well as the cross section of the fusion reactions involved are needed. In general, the energies of interest for BBN are so low (E < 1 MeV) that nuclear cross section measurements are practically unfeasible at the Earth's surface. As of today, LUNA (Laboratory for Underground Nuclear Astrophysics) has been the only facility in the world available to perform direct measurements of small cross section in a very low background radiation. Owing to the background suppression provided by about 1400 meters of rock at the Laboratori Nazionali del Gran Sasso (LNGS), Italy, and to the high current offered by the LUNA accelerator, it has been possible to investigate cross sections at energies of interest for Big Bang nucleosynthesis using protons, 3 He and alpha particles as projectiles. The main reaction studied in the past at LUNA is the 2 H( 4 He, γ) 6 Li. Its cross section was measured directly, for the first time, in the BBN energy range. Other processes like 2 H(p, γ) 3 He, 3 He( 2 H, p) 4 He and 3 He( 4 He, γ) 7 Be were also studied at LUNA, thus enabling to reduce the uncertainty on the overall reaction rate and consequently on the determination of primordial abundances. The improvements on BBN due to the LUNA experimental data will be discussed and a perspective of future measurements will be outlined. (orig.)

  15. Double electron capture by protons in collisions with H2

    International Nuclear Information System (INIS)

    Salazar-Zepeda, M.H.; Gleason, Cristian; Gonzalez, Eduardo; Gonzalez-Magana, O.; Hinojosa, Guillermo

    2010-01-01

    Double electron capture of protons in collisions with molecular hydrogen in the energy range 1.5-10 keV was studied by measuring the resulting H - velocity distributions. In this paper, a technique that provides experimental evidence about double capture mechanisms is proposed. In addition, cross-sections for this process were measured in the energy range of 1-5 keV.

  16. High-Temperature Nucleosynthesis Processes on the Proton-Rich Side of Stability: the Alpha-Rich Freezeout and the rp^2-Process

    Science.gov (United States)

    Meyer, Bradley S.

    2001-10-01

    Nucleosynthesis on the proton-rich side of stability has at least two intriguing aspects. First, the most abundant of the stable iron-group isotopes, such as ^48Ti, ^52Cr, and ^56,57Fe, are synthesized as proton-rich, radioactive parents in alpha-rich freezeouts from equilibrium. The production of these radioactive progenitors depends in large measure on reactions on the proton-rich side of stability. The second intriguing aspect is that explosive nucleosynthesis in a hydrogen-rich environment (namely, the rp-process) may be associated with exotic astrophysical settings, such as x-ray bursts, and may be responsible for production of some of the light p-process nuclei (for example, ^92,94Mo and ^96,98Ru). We have developed web-based tools to help nuclear physicists determine which nuclear reactions on the proton-rich side of stability govern the nucleosynthesis in these processes. For the alpha-rich freezeout, one may determine the effect of any one of 2,140 reactions on the yield of any isotope in the nuclear reaction network with the web calculator. As a relevant example, I will discuss the governing role of ^57Ni (n,p)^57Co in the synthesis of the important astronomical observable ^57Co. As for explosive, proton-rich burning, I will discuss the synthesis of p-process nuclei in the repetitive rp-process (the rp^2-process). movies/rp.html>Movies of the rp^2-process illustrate its important features and give some indications of the important nuclear reactions.

  17. Cross section measurements of proton capture reactions on Se isotopes relevant to the astrophysical p process

    Science.gov (United States)

    Foteinou, V.; Harissopulos, S.; Axiotis, M.; Lagoyannis, A.; Provatas, G.; Spyrou, A.; Perdikakis, G.; Zarkadas, Ch.; Demetriou, P.

    2018-03-01

    Cross sections of proton capture reactions on 74Se, 78Se, and 80Se have been measured at incident beam energies from 2 to 6 MeV, 1.7 to 3 MeV, and 1.5 to 3.5 MeV, respectively. In the case of Se,8078, cross sections were obtained from in-beam γ -angular distribution measurements, whereas for the 74Se isotope they were derived from off-beam activity measurements. The measured cross sections were compared with calculations performed with the nuclear reaction code talys (version 1.6). A good agreement between theory and experiment was found. Astrophysical S factors and reaction rates deduced from the experimental and calculated cross sections were also compared and the impact of different nuclear ingredients in the calculations on the reaction rates was investigated. It was found that, for certain combinations of nuclear input models, the reaction rates obtained at temperatures relevant to p -process nucleosynthesis differ by a factor 2 at the most, differences that are well within the acceptable deviations of calculated p -nuclei abundances and observations.

  18. Radiative proton-capture nuclear processes in metallic hydrogen

    International Nuclear Information System (INIS)

    Ichimaru, Setsuo

    2001-01-01

    Protons being the lightest nuclei, metallic hydrogen may exhibit the features of quantum liquids most relevant to enormous enhancement of nuclear reactions; thermonuclear and pycnonuclear rates and associated enhancement factors of radiative proton captures of high-Z nuclei as well as of deuterons are evaluated. Atomic states of high-Z impurities are determined in a way consistent with the equations of state and screening characteristics of the metallic hydrogen. Rates of pycnonuclear p-d reactions are prodigiously high at densities ≥20 g/cm 3 , pressures ≥1 Gbar, and temperatures ≥950 K near the conditions of solidification. It is also predicted that proton captures of nuclei such as C, N, O, and F may take place at considerable rates, owing to strong screening by K-shell electrons, if the densities ≥60-80 g/cm 3 , the pressures ≥7-12 Gbar, and the temperatures just above solidification. The possibilities and significance of pycnonuclear p-d fusion experiments are specifically remarked

  19. Corrections to primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Dicus, D.A.; Kolb, E.W.; Gleeson, A.M.; Sudarshan, E.C.G.; Teplitz, V.L.; Turner, M.S.

    1982-01-01

    The changes in primordial nucleosynthesis resulting from small corrections to rates for weak processes that connect neutrons and protons are discussed. The weak rates are corrected by improved treatment of Coulomb and radiative corrections, and by inclusion of plasma effects. The calculations lead to a systematic decrease in the predicted 4 He abundance of about ΔY = 0.0025. The relative changes in other primoridal abundances are also 1 to 2%

  20. Precision Mass Measurements of 129-131Cd and Their Impact on Stellar Nucleosynthesis via the Rapid Neutron Capture Process

    CERN Document Server

    Atanasov, D.; Blaum, K.; Cakirli, R.B.; Cocolios, T.E.; George, S.; Herfurth, F.; Kisler, D.; Janka, H.T.; Just, O.; Kowalska, M.; Kreim, S.; Kisler, D.; Litvinov, Yu. A.; Lunney, D.; Manea, V.; Neidherr, D.; Rosenbusch, M.; Schweikhard, L.; Welker, A.; Wienholtz, F.; Wolf, R. N.; Zuber, K.

    2015-01-01

    Masses adjacent to the classical waiting-point nuclide 130Cd have been measured by using the Penning- trap spectrometer ISOLTRAP at ISOLDE/CERN. We find a significant deviation of over 400 keV from earlier values evaluated by using nuclear beta-decay data. The new measurements show the reduction of the N = 82 shell gap below the doubly magic 132Sn. The nucleosynthesis associated with the ejected wind from type-II supernovae as well as from compact object binary mergers is studied, by using state-of-the-art hydrodynamic simulations. We find a consistent and direct impact of the newly measured masses on the calculated abundances in the A = 128 - 132 region and a reduction of the uncertainties from the precision mass input data.

  1. Injection and capture simulations for a high intensity proton synchrotron

    International Nuclear Information System (INIS)

    Cho, Y.; Lessner, E.; Symon, K.; Univ. of Wisconsin, Madison, WI

    1994-01-01

    The injection and capture processes in a high intensity, rapid cycling, proton synchrotron are simulated by numerical integration. The equations of motion suitable for rapid numerical simulation are derived so as to maintain symplecticity and second-order accuracy. By careful bookkeeping, the authors can, for each particle that is lost, determine its initial phase space coordinates. They use this information as a guide for different injection schemes and rf voltage programming, so that a minimum of particle losses and dilution are attained. A fairly accurate estimate of the space charge fields is required, as they influence considerably the particle distribution and reduce the capture efficiency. Since the beam is represented by a relatively coarse ensemble of macro particles, the authors study several methods of reducing the statistical fluctuations while retaining the fine structure (high intensity modulations) of the beam distribution. A pre-smoothing of the data is accomplished by the cloud-in-cell method. The program is checked by making sure that it gives correct answers in the absence of space charge, and that it reproduces the negative mass instability properly. Results of simulations for stationary distributions are compared to their analytical predictions. The capture efficiency for the rapid-cycling synchrotron is analyzed with respect to variations in the injected beam energy spread, bunch length, and rf programming

  2. Primordial Nucleosynthesis

    International Nuclear Information System (INIS)

    Coc, Alain

    2013-01-01

    Primordial nucleosynthesis, or Big Bang Nucleosynthesis (BBN), is one of the three evidences for the Big-Bang model, together with the expansion of the Universe and the Cosmic Microwave Background. There is a good global agreement over a range of nine orders of magnitude between abundances of 4 He, D, 3 He and 7 Li deduced from observations, and calculated in primordial nucleosynthesis. This comparison was used to determine the baryonic density of the Universe. For this purpose, it is now superseded by the analysis of the Cosmic Microwave Background (CMB) radiation anisotropies. However, there remain, a yet unexplained, discrepancy of a factor 3-5, between the calculated and observed lithium primordial abundances, that has not been reduced, neither by recent nuclear physics experiments, nor by new observations. We review here the nuclear physics aspects of BBN for the production of 4 He, D, 3 He and 7 Li, but also 6 Li, 9 Be, 11 B and up to CNO isotopes. These are, for instance, important for the initial composition of the matter at the origin of the first stars. Big-Bang nucleosynthesis, that has been used, to first constrain the baryonic density, and the number of neutrino families, remains, a valuable tool to probe the physics of the early Universe, like variation of ''constants'' or alternative theories of gravity.

  3. Electron capture by fast protons from helium-like ions

    International Nuclear Information System (INIS)

    Samanta, R.; Purkait, M.

    2011-01-01

    Four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation have been applied to calculate the single-electron capture cross sections by fast protons through some helium-like ions in a large energy range from 30-1000 keV. In this model, distortion has been taken into account in the entrance channel. In the final channel, the passive electron plays the role of screening of the target ion. However, continuum states of the projectile and the electron in the field of the residual target ion are included. The comparison of the results is made with those of other theoretical investigations and experimental findings. The present calculated results are found to be in good agreement with the available experimental findings. (authors)

  4. Primordial Nucleosynthesis

    Science.gov (United States)

    Coc, Alain

    Primordial or big bang nucleosynthesis (BBN) is now a parameter free theory whose predictions are in good overall agreement with observations. However, the 7Li calculated abundance is significantly higher than the one deduced from spectroscopic observations. Most solutions to this lithium problem involve a source of extra neutrons that inevitably leads to an increase of the deuterium abundance. This seems now to be excluded by recent deuterium observations that have drastically reduced the uncertainty on D/H and also calls for improved precision on thermonuclear reaction rates.

  5. On some problems of the dynamics of protons captured by geomagnetic fields

    International Nuclear Information System (INIS)

    Kudela, K.; Dubinski, Yu.

    1977-01-01

    Problems on the dynamics of protons captured by the geomagnetic field is reviewed using new experimental data obtained from artificial satellites. The problems on radial and pitch-angular diffusion of high-energy protons on different L-shells are considered. A good agreement is shown to exist between experimental data and diffusion analysis results. The experimental researches of the changes in the fluxes of quasi-captured, captured, and spilled protons are interpreted as a result of the scattering of protons on lowfrequency waves in the magnetosphere. Presented are the graphs of measurement of the flux of spilled and quasi-ca.ptured protons on different L-shells according to the data obtained from the ''ESRO-1A'' and ''Intercosmos-5'' satellites. To clarify the dynamics of the interaction of protons with waves, it is acknowledged as necessary to pay attention to enhancing the role played by a complex character of experiments

  6. Dynamic stellar neutron-capture nucleosynthesis: the need for more nuclear data for the s-process

    International Nuclear Information System (INIS)

    Mathews, G.J.; Howard, W.M.; Takahashi, K.; Ward, R.A.

    1984-09-01

    We summarize results from a detailed parameter study of the s-process in models which produce an exponential distribution of exposures by sequential irradiations and dredge up in the stellar environment. The calculations are based on a complete network of measured and calculated neutron capture and beta-decay rates as well as estimates for their temperature dependence. In the framework of these models we identify and systematically vary the astrophysical variables which affect the observed solar-system sigmaN (cross section times abundance) curve. Constraints are placed on the s-process neutron exposure and flux as well as the temperatures, densities, neutron pulse shape and inter-pulse period. The results also highlight important needs for better nuclear data in various mass regions. 26 references

  7. The Diverse Origins of Neutron-capture Elements in the Metal-poor Star HD 94028: Possible Detection of Products of I-Process Nucleosynthesis

    Science.gov (United States)

    Roederer, Ian U.; Karakas, Amanda I.; Pignatari, Marco; Herwig, Falk

    2016-04-01

    We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H] = -1.62 ± 0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe] = +0.79 ± 0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe] = +0.22 ± 0.12), including unusually large molybdenum ([Mo/Fe] = +0.97 ± 0.16) and ruthenium ([Ru/Fe] = +0.69 ± 0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe] = -0.06 ± 0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99 ± 0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (I process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the I process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the I process may have been common in the early Galaxy. These data are associated with Program 072.B-0585(A), PI. Silva. Some data presented in this paper were obtained from the Barbara A. Mikulski Archive for Space Telescopes (MAST). The Space Telescope Science Institute is

  8. Measurement of proton capture reactions in the hot cycles: an evaluation of experimental methods

    Energy Technology Data Exchange (ETDEWEB)

    Leleux, P [Inst. de Physique Nucleaire, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium)

    1998-06-01

    In the hot cycles, most of the proton capture reactions involve radioactive nuclei in the entrance and exit channels. This paper evaluates the specific methods that were designed to measure such reactions. (orig.)

  9. Laser accelerated protons captured and transported by a pulse power solenoid

    OpenAIRE

    Burris-Mog, T.; Harres, K.; Zielbauer, B.; Bagnoud, V.; Herrmannsdoerfer, T.; Roth, M.; Cowan, T. E.; Nürnberg, F.; Busold, S.; Bussmann, M.; Deppert, O.; Hoffmeister, G.; Joost, M.; Sobiella, M.; Tauschwitz, A.

    2011-01-01

    Using a pulse power solenoid, we demonstrate efficient capture of laser accelerated proton beams and the ability to control their large divergence angles and broad energy range. Simulations using measured data for the input parameters give inference into the phase-space and transport efficiencies of the captured proton beams. We conclude with results from a feasibility study of a pulse power compact achromatic gantry concept. Using a scaled target normal sheath acceleration spectrum, we prese...

  10. Proton injection and RF capture in the national spallation neutron source

    International Nuclear Information System (INIS)

    Luccio, A.U.; Beebe-Wang, J.; Maletic, D.

    1997-01-01

    The accelerator system for the 1 to 5 MW National Spallation Neutron Source (NSNS) consists of a linac followed by a 1 GeV proton accumulator ring. Since the ring is a very high current machine, the injection and rf capture of the protons is deeply affected by transverse and longitudinal space charge effects. Results of numerical simulation of the process are presented together with considerations on methods and results of space charge treatment in high intensity proton storage rings

  11. Primordial nucleosynthesis.

    Science.gov (United States)

    Schramm, D N

    1998-01-06

    With the advent of the new extragalactic deuterium observations, Big Bang nucleosynthesis (BBN) is on the verge of undergoing a transformation. In the past, the emphasis has been on demonstrating the concordance of the BBN model with the abundances of the light isotopes extrapolated back to their primordial values by using stellar and galactic evolution theories. As a direct measure of primordial deuterium is converged upon, the nature of the field will shift to using the much more precise primordial D/H to constrain the more flexible stellar and galactic evolution models (although the question of potential systematic error in 4He abundance determinations remains open). The remarkable success of the theory to date in establishing the concordance has led to the very robust conclusion of BBN regarding the baryon density. This robustness remains even through major model variations such as an assumed first-order quark-hadron phase transition. The BBN constraints on the cosmological baryon density are reviewed and demonstrate that the bulk of the baryons are dark and also that the bulk of the matter in the universe is nonbaryonic. Comparison of baryonic density arguments from Lyman-alpha clouds, x-ray gas in clusters, and the microwave anisotropy are made.

  12. Capture reactions into borromean two-proton systems at rp-waiting points

    DEFF Research Database (Denmark)

    Hove, D.; Jensen, A. S.; Fynbo, H. O. U.

    2016-01-01

    of the radiative capture reactions can be determined. We present numerical results for $E1$ and $E2$ photon emission, and discuss occurrence preferences in general as well as relative sizes of these most likely processes. Finally, we present narrow estimated intervals for the proton capture rates relevant...

  13. Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process. Penning-trap mass measurements of neutron-rich cadmium and caesium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Atanasov, Dinko

    2016-07-06

    Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric proton-to-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similar regions of the nuclear chart and furthermore suitable for r-process studies is still little or even not existing. The basic nuclear properties such as binding energies, half-lives, neutron-induced or neutron-capture reaction cross-sections, play an important role in theoretical simulations and can vary or even drastically alternate results of these studies. Therefore, a considerable effort was put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium ({sup 129-131}Cd) and caesium ({sup 132,146-148}Cs) isotopes. Measurements were done at the on-line radioactive ion-beam facility ISOLDE by using the four-trap mass spectrometer ISOLTRAP. The cadmium isotopes are key nuclides for the synthesis of stable isotopes around the mass peak A = 130 in the Solar System abundance.

  14. Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process Penning-trap mass measurements of neutron-rich cadmium and caesium isotopes

    CERN Document Server

    AUTHOR|(CDS)2085660; Litvinov, Yuri A.; Kreim, Susanne

    Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric proton- to-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similar regions of the nuclear chart and furthermore suitable for r-process studies is still little or even not existing. The basic nuclear properties such as binding energies, half-lives, neutron-induced or neutron-capture reaction cross-sections, play an important role in theoretical simulations and can vary or even drastically alternate results of these studies. Therefore, a considerable effort was put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium (129−131 Cd) and caesium...

  15. On the introduction of {sup 17}O+p reaction rates evaluated through the THM in AGB nucleosynthesis calculations

    Energy Technology Data Exchange (ETDEWEB)

    Palmerini, S.; Sergi, M. L.; La Cognata, M.; Pizzone, R. G. [I.N.F.N. Laboratori Nazionali del Sud, via Santa Sofia 62, Catania (Italy); Lamia, L.; Spitaleri, C. [Dipartimento di Fisica e Astronomia, Universitá degli Studi di Catania (Italy)

    2014-05-09

    The rates for the {sup 17}O(p,αα{sup 14}N, {sup 17}O(p,α){sup 18}F and {sup 18}O(p,α){sup 15}N reactions deduced trough the Trojan Horse Method (THM) have been introduced into a state-of-the-art asymptotic giant branch (AGB) models for proton-capture nucleosynthesis and cool bottom process. The predicted abundances have been compared with isotopic compositions provided by geochemical analysis of presolar grains. As a result, an improved agreement is found between the models and the isotopic mix of oxide grains of AGB origins, whose composition is the signature of low-temperature proton-capture nucleosynthesis.

  16. Strange Meson Radiative Capture on the Proton in Low Energy QCD Lagrangian

    Institute of Scientific and Technical Information of China (English)

    ZHOULi-Juan; MAWei-Xing; 等

    2002-01-01

    Based on our low energy QCD Lagrangian description of strange meson photoproduction off the proton and the crossing symmetry,the strange meson radiative capture on the proton,K-+p→γ+A,is investigated in the [SU SF(6)×O(3)]sym,SUc(3) quark model of baryon structure with the same input parameter,the only strong coupling constant αM,as that in the strange meson photoproduction off the proton γ+p-→K+ Α,a crossing channel of the capture reaction,A good agreement on the branching ratio between the predictions and data is obtained successfully.This excellent fit indicates that our low energy QCD Lagrangian theory with only one free parameter is an advanced and unified description of strange meson photoproduction and its associated radiative capture.

  17. Laser accelerated protons captured and transported by a pulse power solenoid

    Directory of Open Access Journals (Sweden)

    T. Burris-Mog

    2011-12-01

    Full Text Available Using a pulse power solenoid, we demonstrate efficient capture of laser accelerated proton beams and the ability to control their large divergence angles and broad energy range. Simulations using measured data for the input parameters give inference into the phase-space and transport efficiencies of the captured proton beams. We conclude with results from a feasibility study of a pulse power compact achromatic gantry concept. Using a scaled target normal sheath acceleration spectrum, we present simulation results of the available spectrum after transport through the gantry.

  18. Differential cross section measurement of radiative capture of protons by nuclei 12C

    International Nuclear Information System (INIS)

    Burtebayev, N.; Zazulin, D.M.; Buminskii, V.P.; Zarifov, R.A.; Tohtarov, R.N.; Sagindykov, Sh.Sh.; Baktibayev, M.K.

    2003-01-01

    Measurements of differential cross sections of nuclear reaction 12 C(p, γ) 13 N at 0, 45, 90, 135 Deg. to beam direction of flying protons in the field of E p = 350-1100 KeV with an error it is not worse than 10 % have been carried out. Most important was studied, from the astrophysical point of view, process of capture of protons by nucleuses 12 C on the ground state of a nucleus 13 N. It is experimentally shown isotropy of angular distribution of differential cross sections of reaction 12 C(p, γ) 13 N, in the given field energy of protons

  19. Radiative proton-deuteron capture in a gauge invariant relativistic model

    NARCIS (Netherlands)

    Korchin, AY; Van Neck, D; Scholten, O; Waroquier, M

    A relativistic model is developed for the description of the process p+dHe-3+gamma*. It is based on the impulse approximation, but is explicitly gauge invariant and Lorentz covariant. The model is applied to radiative proton-deuteron capture and electrodisintegration of He-3 nt intermediate

  20. Production of e(+)e(-) pairs in proton-deuteron capture to He-3

    NARCIS (Netherlands)

    Korchin, AY; Van Neck, D; Waroquier, M; Scholten, O; Dieperink, AEL

    1998-01-01

    The process p + d He-3 + gamma * at intermediate energies is described using a covariant and gauge-invariant model, and a realistic pd(3)He vertex, Both photodisintegration of He-3 and proton-deuteron capture with production of e(+)e(-) pairs are studied, and results for cross sections and response

  1. The primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Audouze, J.

    1984-01-01

    This review of the primordial nucleosynthesis is divided in three chapters. In the first the author attempts to determine the primordial abundances of the lightest elements which can be formed by the Big Bang nucleosynthesis. The second is a summary of the Standard Big Bang nucleosynthesis. This simple and attractive model might be found in difficulty in the case of a primordial abundance of He <= 0.24 and/or in the case of models of galactic evolution allowing infall of external matter having a primordial composition. Finally, in the third, two alternative proposals to the Standard Big Bang nucleosynthesis are summarized. (Auth.)

  2. A new target concept for proton accelerator driven boron neutron capture therapy applications

    International Nuclear Information System (INIS)

    Powell, J.R.; Ludewig, H.; Todosow, M.; Reich, M.

    1998-01-01

    A new target concept termed Discs Incorporating Sector Configured Orbiting Sources (DISCOS), is proposed for spallation applications, including BNCT (Boron Neutron Capture Therapy). In the BNCT application a proton beam impacts a sequence of ultra thin lithium DISCOS targets to generate neutrons by the 7 Li(p,n) 7 Be reaction. The proton beam loses only a few keV of its ∼MeV energy as it passes through a given target, and is re-accelerated to its initial energy, by a DC electric field between the targets

  3. IMPACT OF NEW GAMOW–TELLER STRENGTHS ON EXPLOSIVE TYPE IA SUPERNOVA NUCLEOSYNTHESIS

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Suzuki, Toshio [National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Hidaka, Jun [Mechanical Engineering Department, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506 (Japan); Honma, Michio [Center for Mathematical Sciences, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Iwamoto, Koichi [Department of Physics, College of Science and Technology, Nihon University, Tokyo 101-8308 (Japan); Nomoto, Ken’ichi [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Otsuka, Takaharu, E-mail: kanji.mori@nao.ac.jp, E-mail: kajino@nao.ac.jp, E-mail: michael.famiano@wmich.edu, E-mail: suzuki@phys.chs.nihon-u.ac.jp, E-mail: jun.hidaka@meisei-u.ac.jp, E-mail: m-honma@u-aizu.ac.jp, E-mail: iwamoto@phys.cst.nihon-u.ac.jp, E-mail: nomoto@astron.s.u-tokyo.ac.jp, E-mail: otsuka@phys.s.u-tokyo.ac.jp [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2016-12-20

    Recent experimental results have confirmed a possible reduction in the Gamow–Teller (GT{sub +}) strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of SNe Ia. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT{sub +} strength can result in a slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed that more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of SNe Ia, and the final mass fractions are compared to those obtained using more commonly used rates.

  4. Low-energy photodisintegration of the deuteron and Big-Bang nucleosynthesis

    International Nuclear Information System (INIS)

    Tornow, W.; Czakon, N.G.; Howell, C.R.; Hutcheson, A.; Kelley, J.H.; Litvinenko, V.N.; Mikhailov, S.F.; Pinayev, I.V.; Weisel, G.J.; Witala, H.

    2003-01-01

    The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the high-intensity gamma-ray source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang nucleosynthesis. Our data are in excellent agreement with potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density Ω B h 2 obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%

  5. Low-energy photodisintegration of the deuteron and Big-Bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Tornow, W.; Czakon, N.G.; Howell, C.R.; Hutcheson, A.; Kelley, J.H.; Litvinenko, V.N.; Mikhailov, S.F.; Pinayev, I.V.; Weisel, G.J.; Witala, H

    2003-11-06

    The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the high-intensity gamma-ray source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang nucleosynthesis. Our data are in excellent agreement with potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density {omega}{sub B}h{sup 2} obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%.

  6. Strange Meson Radiative Capture on the Proton in Low Energy QCD Lagrangian

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li-Juan; MA Wei-Xing

    2002-01-01

    Based on our low energy QCD Lagrangian description of strange meson photoproduction off the protonand the crossing symmetry, the strange meson radiative capture on the proton, K- + p →γ + A, is investigated in the[SUsF (6) O(3)]sym. SUc (3) quark model of baryon structure with the same input parameter, the only strong couplingconstant aM, as that in the strange meson photoproduction off the proton γ + p → K+ + A, a crossing channel of thecapture reaction. A good agreement on the branching ratio between the predictions and data is obtained successfully.This excellent fit indicates that our low energy QCD Lagrangian theory with only one free parameter is an advancedand unified description of strange meson photoproduction and its associated radiative capture.

  7. Electron capture in proton collisions with alkali atoms as a three-body problem

    International Nuclear Information System (INIS)

    Avakov, G.V.; Blokhintsev, L.D.; Kadyrov, A.S.; Mukhamedzhanov, A.M.

    1992-01-01

    A previous paper proposed an approach to the calculation of electron transfer reactions in ion-atomic collisions based on the Faddeev three-body equations written in the Alt-Grassberger-Sandhas form. In the present work this approach is used to describe the electron capture in proton collisions with alkali atoms. The results of calculation of the total and partial cross sections for charge exchange in proton collisions with Li, Na, K and Rb atoms are presented. The calculated total cross sections are in good agreement with experiment for light target atoms. In going over to heavier targets, the theoretical total cross sections, while agreeing in form, tend to be larger than the experimental ones. The calculated partial cross sections for electron capture into the 2s state of the H atom are also in agreement with experiment. Some other partial cross sections were also calculated. (author)

  8. Radiative proton capture to the first excited state of sup 29 P nucleus at subbarrier energies

    Energy Technology Data Exchange (ETDEWEB)

    Matulewicz, T; Dabrowska, M; Decowski, P; Kicinska-Habior, M; Sikora, B [Warsaw Univ. (Poland). Inst. Fizyki Doswiadczalnej; Toke, J [Rochester Univ., NY (USA). Nuclear Structure Research Lab.; Somorjai, E [Magyar Tudomanyos Akademia, Debrecen (Hungary). Atommag Kutato Intezete

    1985-08-01

    Differential cross sections at 0 deg and 90 deg measured for {sup 28}Si(p,{gamma}{sub 1}){sup 29}P reaction at proton energy range 2.3-2.9 MeV have been analyzed in terms of the direct-semidirect capture model extended by the effective potential approach. Spectroscopic factor of the first excited states of {sup 29}P nucleus was found to be 0.10+-0.05. 9 refs., 1 fig. (author).

  9. Differential cross section measurement of radiative capture of protons by nuclei 13C

    International Nuclear Information System (INIS)

    Baktibayev, M.K.; Burminskii, V.P.; Burtebayev, N.; Dzazairov-Kakhramanov, V.; Kadyrzhanov, K.K.; Sagindykov, Sh.Sh.; Zarifov, R.A.; Zazulin, D.M.

    2004-01-01

    Full text: The reaction 13 C(p,γ ) 14 N is the important one for the astrophysics, not only for nuclear synthesis of CNO elements, but and for nuclear synthesis of elements participating in subsequent combustion of helium [1]. The predominant yield of the reaction occurs at protons energies of less than 1 MeV. However, the clearness of the capture mechanism in this energy region is made difficult because of the superposition of the contribution of the low - energetical part of the resonance 1320 keV onto the cross section. Last experimental data for more wide energy region, informed in the work [1], and results of previous works, mentioned in that work, give reason for further continuation of the study of the reaction 13 C(p,γ ) 14 N. Measured data of the work [1] in the region of E ρ = (320 † 900) keV at the angles of 0 o and 90 o are obviously insufficient. In the present work measurements of differential cross sections of the reaction were carried out at protons energies E p = 991, 558 and 365 keV, the accuracy is not worse then 10%. There was studied the most (from the astrophysical point of view) important process of protons capture by 13 C nuclei onto the ground state of the 14 N nucleus. The 13 C (99%) targets, used in the experiment, were sprayed onto copper base. The target thickness was determined by incident protons energy losses in the target. The energy losses were clearly reflected in the corresponding spreading of transitions of radiation capture. The statement about the gamma-lines spreading is valid in this case, because energy losses in the target are here significantly more, than the energetical resolution of the detector. The peak width of the radiation capture gamma-line at half-height corresponds to energy losses of incident protons in the target. From the Table of brake values for protons in carbon [2] there was determined that the thickness of the target was 140 ± 5% μg/cm 2 . The upper part of gamma-lines in the spectrum repeats the

  10. Warp simulations for capture and control of laser-accelerated proton beams

    International Nuclear Information System (INIS)

    Nuernberg, Frank; Harres, K; Roth, M; Friedman, A; Grote, D P; Logan, B G; Schollmeier, M

    2010-01-01

    The capture of laser-accelerated proton beams accompanied by co-moving electrons via a solenoid field has been studied with particle-in-cell simulations. The main advantages of the Warp simulation suite that we have used, relative to envelope or tracking codes, are the possibility of including all source parameters energy resolved, adding electrons as second species and considering the non-negligible space-charge forces and electrostatic self-fields. It was observed that the influence of the electrons is of vital importance. The magnetic effect on the electrons outbalances the space-charge force. Hence, the electrons are forced onto the beam axis and attract protons. Beside the energy dependent proton density increase on axis, the change in the particle spectrum is also important for future applications. Protons are accelerated/decelerated slightly, electrons highly. 2/3 of all electrons get lost directly at the source and 27% of all protons hit the inner wall of the solenoid.

  11. Warp simulations for capture and control of laser-accelerated proton beams

    International Nuclear Information System (INIS)

    Nurnberg, F.; Friedman, A.; Grote, D.P.; Harres, K.; Logan, B.G.; Schollmeier, M.; Roth, M.

    2009-01-01

    The capture of laser-accelerated proton beams accompanied by co-moving electrons via a solenoid field has been studied with particle-in-cell simulations. The main advantages of the Warp simulation suite that was used, relative to envelope or tracking codes, are the possibility of including all source parameters energy resolved, adding electrons as second species and considering the non-negligible space-charge forces and electrostatic self-fields. It was observed that the influence of the electrons is of vital importance. The magnetic effect on the electrons out balances the space-charge force. Hence, the electrons are forced onto the beam axis and attract protons. Besides the energy dependent proton density increase on axis, the change in the particle spectrum is also important for future applications. Protons are accelerated/decelerated slightly, electrons highly. 2/3 of all electrons get lost directly at the source and 27% of all protons hit the inner wall of the solenoid.

  12. Magnetic moment calculation for p+d→ 3 He+γ process in Big=bang nucleosynthesis with effective field theory

    International Nuclear Information System (INIS)

    Bayegan, S.; Sadeghi, H.

    2004-01-01

    In big-bang nucleosynthesis, processes relevant ti increasing of nucleon density are more important. One of the theories that its solutions more accurately explain the experimental works is Effective Field Theory in this paper. Magnetic moment (χM1) for radiative capture of protons by deuterons p + d → 3 He+γ process is calculated using Effective Field Theory. The calculation includes coulomb interaction up to next-to -next-leading order (N 2 LO)

  13. Differential cross section measurement of radiative capture of protons by nuclei 13C

    International Nuclear Information System (INIS)

    Baktibayev, M.K.; Burminskii, V.P.; Burtebayev, N.; Jazairov-Kakhramanov, V.; Kadyrzhanov, K.K.; Sagindykov, Sh.Sh.; Zarifov, R.A.; Zazulin, D.M.

    2004-01-01

    The reaction 13 C(p,γ ) 14 N is the important one for the astrophysics, not only for nuclear synthesis of CNO elements, but also for nuclear synthesis of elements participating in subsequent combustion of helium [1]. The predominant yield of the reaction occurs at protons energies of less than 1 MeV. However, the clearness of the capture mechanism in this energy region is made difficult because of the superposition of the contribution of the low - energy part of the resonance 1320 keV onto the cross section. Last experimental data for a wider energy region, informed in the work [1], and results of previous works, mentioned in that work, give reason for further continuation of the study of the reaction 13 C(p,γ ) 14 N. Measured data of the work [1] in the region of E P = (320 - 900) keV at the angles of 0 o and 90 o are obviously insufficient. In the present work measurements of differential cross sections of the reaction were carried out at protons energies E P = 991 - 365 keV, the accuracy is not worse than 10%. There was studied the most (from the astrophysical point of view) important process of protons capture by 13 C nuclei onto the ground state of the 14 N nucleus. The theoretical investigation of the given reaction included calculation of cross sections. The cross sections were calculated within the framework of model of direct capture with the using of optical potentials for the description of a channel of scattering. The wave functions of a bound state were generated in a potential reproducing binding energy of a proton in 14 N nucleus. Results of calculations were compared with the experimental data. (author)

  14. Nucleosynthesis outreach slides

    Energy Technology Data Exchange (ETDEWEB)

    Lippuner, Jonas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-03

    The purpose of this report is to explain s- and r-process nucleosynthesis to the general public at outreach events, specifically in a Planetarium show at the Pajarito Environmental Education Center in Los Alamos.

  15. Sun's dynamics and nucleosynthesis

    International Nuclear Information System (INIS)

    Gavanescu, Adela; Rusu, Mircea V.

    2005-01-01

    Nucleosynthesis processes in the sun are one of the main results related to the evolution of the Sun. Dynamics and energetics of the Sun could be studied indirectly by their elements products in produced by nucleosynthesis. Also solar atmosphere and its characteristics reveled in its full development is observed during the solar eclipses. We try to correlate these facts in order to obtained data to be used in solar models. (authors)

  16. Radiative capture of cold neutrons by protons and deuteron photodisintegration with twisted beams

    Science.gov (United States)

    Afanasev, Andrei; Serbo, Valeriy G.; Solyanik, Maria

    2018-05-01

    We consider two basic nuclear reactions: capture of neutrons by protons, n + p → γ + d, and its time-reversed counterpart, photodisintegration of the deuteron, γ + d → n + p. In both of these cases we assume that the incoming beam of neutrons or photons is ‘twisted’ by having an azimuthal phase dependence, i.e., it carries an additional angular momentum along its direction of propagation. Taking a low-energy limit of these reactions, we derive relations between corresponding transition amplitudes and cross sections with plane-wave beams and twisted beams. Implications for experiments with twisted cold neutrons and twisted photon beams are discussed.

  17. The boundary-corrected second Born (B2B) approximation: proton-hydrogen electron capture

    International Nuclear Information System (INIS)

    Dewangan, D.P.; Bransden, B.H.

    1988-01-01

    The probability amplitude for proton-hydrogen ground-state electron capture at 125 keV in the boundary-corrected second Born approximation has been evaluated numerically by retaining all significant bound and continuum hydrogenic intermediate states for which the orbital angular momentum l ≤ 3. The differential cross section is found to be in good agreement with the experimental data for scattering angles less than about 1 mrad in the centre of mass system. The value of the boundary-corrected second Born total cross section is similar to that obtained in the boundary-corrected first Born approximation. (author)

  18. Nucleosynthesis in nova outbursts

    International Nuclear Information System (INIS)

    Iliadis, C.; Azuma, R.E.; Buchmann, L.

    1994-02-01

    Astronomical observations have shown that He, CNO material and/or heavy elements are considerably enriched in certain nova ejecta relative to solar matter. The heavy element enrichments can be explained by the dredge-up of matter from an underlying ONeMg white dwarf and subsequent redistribution of the material by the rp-process. The proton capture reactions on 32 S and 36 A r important for hydrogen burning during nova outbursts have been measured experimentally. The derived stellar reaction rates have been incorporated into large-scale network calculations and the astrophysical consequences are discussed. (author)

  19. Nucleosynthesis in nova outbursts

    Energy Technology Data Exchange (ETDEWEB)

    Iliadis, C [TRIUMF, Vancouver, BC (Canada); [Univ. of Toronto, McLennan Physical Labs., Toronto, ON (Canada); Azuma, R E [Univ. of Toronto, McLennan Physical Lab., Toronto, ON (Canada); Buchmann, L [TRIUMF, Vancouver, BC (Canada); and others

    1994-02-01

    Astronomical observations have shown that He, CNO material and/or heavy elements are considerably enriched in certain nova ejecta relative to solar matter. The heavy element enrichments can be explained by the dredge-up of matter from an underlying ONeMg white dwarf and subsequent redistribution of the material by the rp-process. The proton capture reactions on 32{sup S} and 36{sup A}r important for hydrogen burning during nova outbursts have been measured experimentally. The derived stellar reaction rates have been incorporated into large-scale network calculations and the astrophysical consequences are discussed. (author) 17 refs., 2 figs.

  20. Electron correlations in single-electron capture from helium by fast protons and α particles

    International Nuclear Information System (INIS)

    Mancev, Ivan; Milojevic, Nenad

    2010-01-01

    Single-electron capture from heliumlike atomic systems by bare projectiles is investigated by means of the four-body boundary-corrected first Born approximation (CB1-4B). The effect of the dynamic electron correlation is explicitly taken into account through the complete perturbation potential. The quantum-mechanical post and prior transition amplitudes for single charge exchange encompassing symmetric and/or asymmetric collisions are derived in terms of two-dimensional real integrals in the case of the prior form and five-dimensional quadratures for the post form. An illustrative computation is performed for single-electron capture from helium by protons and α particles at intermediate and high impact energies. The role of dynamic correlations is examined as a function of increased projectile energy. The validity and utility of the proposed CB1-4B method is critically assessed in comparison with the existing experimental data for total cross sections, and excellent agreement is obtained.

  1. Proton capture to the ground and excited states in light nuclei

    International Nuclear Information System (INIS)

    Anghinolfi, M.; Corvisiero, P.; Guarnone, M.; Ricco, G.; Sanzone, M.; Taiuti, M.; Zucchiatti, A.

    1984-01-01

    Proton capture experiments, when performed with good resolution, generally provide two different kinds of physical information; the ground-state pγ/sub o/ cross section, which is related, through the detailed balance, to the inverse photonuclear γp/sub o/ reaction; the advantage of capture experiments is the definite kinematics, corresponding to monochromatic photons in γp reactions, and a more precise beam monitoring. The pγ/sub x/ cross section to the various excited states of the final nucleus; this information is typical of capture experiments, since excited nuclear targets are not available. Many laboratories performed extensive capture experiments at excitation energies up to the GDR region, but only recently few groups (Ohio, Triangle and Genova Universities) extended the investigation to energies above the GDR. In fact more severe experimental problems arise at higher energies: since the pγ differential cross sections range in this energy region between 0.1 and 1Γb/sr, while competitive reactions have two or three order of magnitude higher cross sections, the signal-to-background ratio is very low. The data analysis strongly depends on the detector line shape, scarsely known at photon energies above 20 MeV; a very accurate knowledge of the detector response function is therefore necessary

  2. Big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Boyd, Richard N.

    2001-01-01

    The precision of measurements in modern cosmology has made huge strides in recent years, with measurements of the cosmic microwave background and the determination of the Hubble constant now rivaling the level of precision of the predictions of big bang nucleosynthesis. However, these results are not necessarily consistent with the predictions of the Standard Model of big bang nucleosynthesis. Reconciling these discrepancies may require extensions of the basic tenets of the model, and possibly of the reaction rates that determine the big bang abundances

  3. Explosive processes in nucleosynthesis

    International Nuclear Information System (INIS)

    Boyd, R.N.

    2002-01-01

    There are many explosive processes in nucleosynthesis: big bang nucleosynthesis, the rp-process, the γ-process, the ν-process, and the r-process. However, I will discuss just the rp-process and the r-process in detail, primarily because both seem to have been very active research areas of late, and because they have great potential for studies with radioactive nuclear beams. I will also discuss briefly the γ-process because of its inevitability in conjunction with the rp-process. (orig.)

  4. Neutron-capture reactions by stable and unstable neutron-rich nuclei and their relevance for nucleosynthesis in hot and explosive astrophysical scenarios

    International Nuclear Information System (INIS)

    Hofinger, R.

    1997-10-01

    This thesis deals on the one hand with neutron-capture reactions by carbon-, nitrogen-, oxygen- and sulfur-isotopes, and on the other hand with the two-step processes 4 He(2n, γ) 6 He and 9 Li(2n, γ) 11 Li. Some of the involved carbon-, nitrogen- and oxygen-isotopes possess neutron-halos characterized by the unexpected large radial extension of the nuclear matter density distribution. Special attention is paid to the halo properties in the calculation of the direct neutron capture cross section. For the determination of the nuclear structure, models are used, when no experimental information is available. The results for the reaction rates are compared to previously used rates. The rates obtained in this work are partly orders of magnitude higher than the previously used reaction rates. The reaction rates for the two-step processes are on the one hand calculated assuming a two-step process, on the other hand from genuine three-body models for the process of photodisintegration of the nuclei 6 He and 11 Li. It turns out that the calculations assuming a trio-step process underestimate the reaction rates by orders of magnitude. The influence of the reaction rate for the reaction 4 He(2n, γ) 6 He and the formation of 12 C is examined in a nuclear reaction network under conditions which are typical for the α- process in supernovae of type II. It turns out that under these conditions the influence of the reaction 4 He(2n, γ) 6 He is negligible on the formation of 12 C. (author)

  5. Measurement of the weak nucleon-nucleon interaction by polarized cold neutron capture on protons

    Directory of Open Access Journals (Sweden)

    Alarcon R.

    2014-03-01

    Full Text Available The NPDGamma Experiment at the Spallation Neutron Source at Oak Ridge National Laboratory is measuring the parity-odd correlation between the neutron spin and the direction of the emitted photon in the capture of polarized cold neutrons on protons. A parity violating asymmetry from this process is directly related to the strength of the hadronic weak interaction between nucleons. The experiment was run first with heavier nuclear targets to check systematic effects, false asymmetries, and backgrounds. Since early 2012 the experiment has been collecting data with a 16-liter liquid parahydrogen target. Data taking will continue through 2013 until statistics for a 10−8 asymmetry measurement are expected. The experiment performance will be discussed as well as the status of the asymmetry measurements.

  6. Nucleosynthesis in Core-Collapse Supernovae

    Science.gov (United States)

    Stevenson, Taylor Shannon; Viktoria Ohstrom, Eva; Harris, James Austin; Hix, William R.

    2018-01-01

    The nucleosynthesis which occurs in core-collapse supernovae (CCSN) is one of the most important sources of elements in the universe. Elements from Oxygen through Iron come predominantly from supernovae, and contributions of heavier elements are also possible through processes like the weak r-process, the gamma process and the light element primary process. The composition of the ejecta depends on the mechanism of the explosion, thus simulations of high physical fidelity are needed to explore what elements and isotopes CCSN can contribute to Galactic Chemical Evolution. We will analyze the nucleosynthesis results from self-consistent CCSN simulations performed with CHIMERA, a multi-dimensional neutrino radiation-hydrodynamics code. Much of our understanding of CCSN nucleosynthesis comes from parameterized models, but unlike CHIMERA these fail to address essential physics, including turbulent flow/instability and neutrino-matter interaction. We will present nucleosynthesis predictions for the explosion of a 9.6 solar mass first generation star, relying both on results of the 160 species nuclear reaction network used in CHIMERA within this model and on post-processing with a more extensive network. The lowest mass iron core-collapse supernovae, like this model, are distinct from their more massive brethren, with their explosion mechanism and nucleosynthesis being more like electron capture supernovae resulting from Oxygen-Neon white dwarves. We will highlight the differences between the nucleosynthesis in this model and more massive supernovae. The inline 160 species network is a feature unique to CHIMERA, making this the most sophisticated model to date for a star of this type. We will discuss the need and mechanism to extrapolate the post-processing to times post-simulation and analyze the uncertainties this introduces for supernova nucleosynthesis. We will also compare the results from the inline 160 species network to the post-processing results to study further

  7. Estimates of the astrophysical S-factors for proton radiative capture by 10B and 24Mg nuclei using the ANCs from proton transfer reactions

    International Nuclear Information System (INIS)

    Artemov, S.V.; Igamov, S.B.; Karakhodzhaev, A.A.; Nie, G.K.; Yarmukhamedov, R.; Zaparov, E.A.; Burtebaev, N.; Rehm, K.E.

    2010-01-01

    The contribution of the direct radiative capture of protons by 10 B and 24 Mg nuclei at low energies to the astrophysical S-factors in the reactions 10 B(p,γ) 11 C and 24 Mg(p,γ) 25 Al have been calculated within the R-matrix formalism by using empirical proton asymptotical normalization coefficients (ANC). The ANCs for bound proton configurations { 10 B+p} and { 24 Mg+p} were obtained from the analysis of the reactions ( 3 He, d). The ANCs were also estimated from the values of the neutron ANCs in the mirror nucleus 25 Mg following the suggestion that the neutron and the proton in the mirror states have equivalent nuclear potentials. It has been found that the S-factor for the reaction 10 B(p,γ) 11 C extrapolated to zero energy contributes ~100 keV b to the radiative capture to the ground state of 11 C. For the reaction 24 Mg(p,γ) 25 Al the value S(0) gives 58 keV b with a direct capture contribution of 41 keV b. (author)

  8. Nucleosynthesis in stellar explosions

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, S.E.; Axelrod, T.S.; Weaver, T.A.

    1983-01-01

    The final evolution and explosion of stars from 10 M/sub solar/ to 10/sup 6/ M/sub solar/ are reviewed with emphasis on factors affecting the expected nucleosynthesis. We order our paper in a sequence of decreasing mass. If, as many suspect, the stellar birth function was peaked towards larger masses at earlier times (see e.g., Silk 1977; but also see Palla, Salpeter, and Stahler 1983), this sequence of masses might also be regarded as a temporal sequence. At each stage of Galactic chemical evolution stars form from the ashes of preceding generations which typically had greater mass. A wide variety of Type I supernova models, most based upon accreting white dwarf stars, are also explored using the expected light curves, spectra, and nucleosynthesis as diagnostics. No clearly favored Type I model emerges that is capable of simultaneously satisfying all three constraints.

  9. Nucleosynthesis in stellar explosions

    International Nuclear Information System (INIS)

    Woosley, S.E.; Axelrod, T.S.; Weaver, T.A.

    1983-01-01

    The final evolution and explosion of stars from 10 M/sub solar/ to 10 6 M/sub solar/ are reviewed with emphasis on factors affecting the expected nucleosynthesis. We order our paper in a sequence of decreasing mass. If, as many suspect, the stellar birth function was peaked towards larger masses at earlier times (see e.g., Silk 1977; but also see Palla, Salpeter, and Stahler 1983), this sequence of masses might also be regarded as a temporal sequence. At each stage of Galactic chemical evolution stars form from the ashes of preceding generations which typically had greater mass. A wide variety of Type I supernova models, most based upon accreting white dwarf stars, are also explored using the expected light curves, spectra, and nucleosynthesis as diagnostics. No clearly favored Type I model emerges that is capable of simultaneously satisfying all three constraints

  10. Nucleosynthesis in Supernovae

    Science.gov (United States)

    Thielemann, Friedrich-Karl; Isern, Jordi; Perego, Albino; von Ballmoos, Peter

    2018-04-01

    We present the status and open problems of nucleosynthesis in supernova explosions of both types, responsible for the production of the intermediate mass, Fe-group and heavier elements (with the exception of the main s-process). Constraints from observations can be provided through individual supernovae (SNe) or their remnants (e.g. via spectra and gamma-rays of decaying unstable isotopes) and through surface abundances of stars which witness the composition of the interstellar gas at their formation. With a changing fraction of elements heavier than He in these stars (known as metallicity) the evolution of the nucleosynthesis in galaxies over time can be determined. A complementary way, related to gamma-rays from radioactive decays, is the observation of positrons released in β+-decays, as e.g. from ^{26}Al, ^{44}Ti, ^{56,57}Ni and possibly further isotopes of their decay chains (in competition with the production of e+e- pairs in acceleration shocks from SN remnants, pulsars, magnetars or even of particle physics origin). We discuss (a) the role of the core-collapse supernova explosion mechanism for the composition of intermediate mass, Fe-group (and heavier?) ejecta, (b) the transition from neutron stars to black holes as the final result of the collapse of massive stars, and the relation of the latter to supernovae, faint supernovae, and gamma-ray bursts/hypernovae, (c) Type Ia supernovae and their nucleosynthesis (e.g. addressing the ^{55}Mn puzzle), plus (d) further constraints from galactic evolution, γ-ray and positron observations. This is complemented by the role of rare magneto-rotational supernovae (related to magnetars) in comparison with the nucleosynthesis of compact binary mergers, especially with respect to forming the heaviest r-process elements in galactic evolution.

  11. Big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Fields, Brian D.; Olive, Keith A.

    2006-01-01

    We present an overview of the standard model of big bang nucleosynthesis (BBN), which describes the production of the light elements in the early universe. The theoretical prediction for the abundances of D, 3 He, 4 He, and 7 Li is discussed. We emphasize the role of key nuclear reactions and the methods by which experimental cross section uncertainties are propagated into uncertainties in the predicted abundances. The observational determination of the light nuclides is also discussed. Particular attention is given to the comparison between the predicted and observed abundances, which yields a measurement of the cosmic baryon content. The spectrum of anisotropies in the cosmic microwave background (CMB) now independently measures the baryon density to high precision; we show how the CMB data test BBN, and find that the CMB and the D and 4 He observations paint a consistent picture. This concordance stands as a major success of the hot big bang. On the other hand, 7 Li remains discrepant with the CMB-preferred baryon density; possible explanations are reviewed. Finally, moving beyond the standard model, primordial nucleosynthesis constraints on early universe and particle physics are also briefly discussed

  12. Excitations of one-valence-proton, one-valence-neutron nucleus {sup 210}Bi from cold-neutron capture

    Energy Technology Data Exchange (ETDEWEB)

    Cieplicka-Oryńczak, N. [INFN sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków (Poland); Fornal, B.; Szpak, B. [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków (Poland); Leoni, S.; Bottoni, S. [INFN sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Bazzacco, D. [Dipartimento di Fisica e Astronomia dell’Università, I-35131 Padova (Italy); INFN Sezione di Padova, I-35131 Padova (Italy); Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T. [Institute Laue-Langevin, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Bocchi, G. [Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); France, G. de [GANIL, Bd. Becquerel, BP 55027, 14076 CAEN Cedex 05 (France); Simpson, G. [LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, F-38026 Grenoble Cedex (France); Ur, C. [INFN Sezione di Padova, Via F. Marzolo 8, I-35131 Padova (Italy); Urban, W. [Faculty of Physics, University of Warsaw, ul. Hoża 69, 02-681, Warszawa (Poland)

    2015-10-15

    The low-spin structure of one-proton, one-neutron {sup 210}Bi nucleus was investigated in cold-neutron capture reaction on {sup 209}Bi. The γ-coincidence measurements were performed with use of EXILL array consisted of 16 HPGe detectors. The experimental results were compared to shell-model calculations involving valence particles excitations. The {sup 210}Bi nucleus offers the potential to test the effective proton-neutron interactions because most of the states should arise from the proton-neutron excitations. Additionally, it was discovered that a few states should come from the couplings of valence particles to the 3{sup −} octupole vibration in {sup 208}Pb which provides also the possibility of testing the calculations involving the core excitations.

  13. Big bang nucleosynthesis and the cosmic neutrino background

    International Nuclear Information System (INIS)

    Cao Yun; Xing Zhizhong

    2013-01-01

    We present a brief overview of the neutrino decoupling and big bang nucleosynthesis in the early universe. The big bang relic neutrinos formed one of the backgrounds of the universe. A few possible ways to directly detect the cosmic neutrino background are briefly introduced, and particular attention is paid to the relic neutrino capture on b-decaying nuclei. (authors)

  14. Photinos and primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Salati, P.

    1986-07-01

    Photinos are among the most interesting particles predicted by supersymmetric theories. If they exist they should influence in many ways the results of the primordial nucleosynthesis i.e. the predicted primordial abundances of D, 3 He, 4 He (and 7 Li). If photinos are stable, cosmological constraints restrict their possible mass to be either very light (M∼ γ γ > a few GeV), depending on the slepton and squark masses. In the case where photinos are unstable, they could create high energy photons able to photodisintegrate the light elements. The comparison between the predicted and the observed abundances allows to restrict significantly the photino mass-lifetime range: roughly speaking photinos of relatively high mass (M∼ γ > 150 MeV) and low time scale ( 3 sec) are compatible with these abundances

  15. Nucleosynthesis in the early Galaxy: Progress and challenges.

    Science.gov (United States)

    Montes, Fernando

    2015-10-01

    Chemical imprints left by the first stars in the oldest stars of the Milky Way gives clues of the stellar nucleosynthesis responsible for the creation of elements heavier than iron. Recent progress in astronomical observations and in the modeling of the chemical evolution of the Galaxy have shown that multiple nucleosynthesis processes may operate at those early times. In this talk I will review some of that evidence along with the important role that nuclear reactions play in those processes. I will focus in progress in our understanding of the rapid neutron capture process (r-process) and in new results on nucleosynthesis in core-collapse supernovae and neutrino-driven winds that produce elements up to silver. I will show some examples of recent nuclear physics measurements addressing the need for better nuclear data and give an outlook of the remaining challenges and future plans to continue those measurements.

  16. Neutrinos and nucleosynthesis in supernova

    Energy Technology Data Exchange (ETDEWEB)

    Solis, U [Instituto de Ciencias Nucleares, Departamento de Fisica de Altas EnergIas, Universidad Nacional Autonoma de Mexico (ICN-UNAM). Apartado Postal 70-543, 04510 Mexico, D.F. (Mexico); D' Olivo, J C [Instituto de Ciencias Nucleares, Departamento de Fisica de Altas EnergIas, Universidad Nacional Autonoma de Mexico (ICN-UNAM). Apartado Postal 70-543, 04510 Mexico, D.F. (Mexico); Cabral-Rosetti, L G [Departamento de Posgrado, Centro Interdisciplinario de Investigacion y Docencia en Educacion Tecnica (CIIDET), Av. Universidad 282 Pte., Col. Centro, A. Postal 752, C.P. 76000, Santiago de Queretaro, Qro. (Mexico)

    2006-05-15

    The type II supernova is considered as a candidate site for the production of heavy elements. The nucleosynthesis occurs in an intense neutrino flux, we calculate the electron fraction in this environment.

  17. Neutrinos and nucleosynthesis in supernova

    International Nuclear Information System (INIS)

    Solis, U; D'Olivo, J C; Cabral-Rosetti, L G

    2006-01-01

    The type II supernova is considered as a candidate site for the production of heavy elements. The nucleosynthesis occurs in an intense neutrino flux, we calculate the electron fraction in this environment

  18. Investigation of 65Cu by means of the average resonance proton capture method

    International Nuclear Information System (INIS)

    Erlandsson, B.; Nilsson, K.; Piotrowski, J.

    1979-01-01

    The 64 Ni(p,γ) 65 Cu reaction has been studied in the proton energy range E sub(p) = 2.05 - 2.55 MeV. The gamma-ray spectra were recorded with a three-crystal pair spectrometer at proton energy differences of 19 keV covering the proton energy range. An average gamma-ray spectrum was formed by adding all the individual spectra after proper adjustment as a result of the alterations in proton energy. The intensities of the gamma rays to final states with known J sup(π)-values were tested against theoretical calculations based on the Hauser-Feshbach theory with good results and these made it possible to deduce further J sup(π)-values. (author)

  19. Big-Bang Nucleosynthesis

    CERN Document Server

    Fields, Brian D.; Sarkar, Subir

    2014-01-01

    A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, η, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of η from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range η=(5.7−6.7)×10−10 at 95% CL (corresponding to a cosmological baryon density ΩBh2=0.021−0.025). The D and He-4 abundances, when combined with the CMB determination of η, provide the bound Nν=3.28±0.28 on the effective number of neutrino species. Other constraints on new physics are discussed briefly.

  20. Exchange currents in the radiative capture of thermal neutrons by protons and deuterons

    International Nuclear Information System (INIS)

    Konijnenberg, M.W.

    1990-01-01

    Measurements are presented about the ratio between the contributions to the radiative neutron capture process by deuterons from states with total spin J = 1/2 and J = 3/2. It is shown that the outcome of these experiments can only be understood from the electromagnetic interaction with nucleons, mesons and nucleon resonances involving meson exchange. (author). 112 refs.; 27 figs.; 7 tabs

  1. A Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Induced Pseudoscalar Coupling gp

    International Nuclear Information System (INIS)

    Banks, Thomas Ira

    2007-01-01

    This dissertation describes a measurement of the rate of nuclear muon capture by the proton, performed by the MuCap Collaboration using a new technique based on a time projection chamber operating in ultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPa pressure. The hydrogen target's low gas density of 1 percent compared to liquid hydrogen is key to avoiding uncertainties that arise from the formation of muonic molecules. The capture rate was obtained from the difference between the mu- disappearance rate in hydrogen--as determined from data collected in the experiment's first physics run in fall2004--and the world average for the mu+ decay rate. After combining the results of my analysis with the results from another independent analysis of the 2004 data, the muon capture rate from the hyperfine singlet ground state of the mu-p atom is found to be Λ S = 725.0 ± 17.4 1/s, from which the induced pseudoscalar coupling of the nucleon, gP(q2 = -0.88m2mu)= 7.3 ± 1.1, is extracted. This result for gP is consistent with theoretical predictions that are based on the approximate chiral symmetry of QCD

  2. The r-process nucleosynthesis and related challenges

    Directory of Open Access Journals (Sweden)

    Goriely Stephane

    2017-01-01

    Full Text Available The rapid neutron-capture process, or r-process, is known to be of fundamental importance for explaining the origin of approximately half of the A > 60 stable nuclei observed in nature. Recently, special attention has been paid to neutron star (NS mergers following the confirmation by hydrodynamic simulations that a non-negligible amount of matter can be ejected and by nucleosynthesis calculations combined with the predicted astrophysical event rate that such a site can account for the majority of r-material in our Galaxy. We show here that the combined contribution of both the dynamical (prompt ejecta expelled during binary NS or NS-black hole (BH mergers and the neutrino and viscously driven outflows generated during the post-merger remnant evolution of relic BH-torus systems can lead to the production of r-process elements from mass number A ≳ 90 up to actinides. The corresponding abundance distribution is found to reproduce the solar distribution extremely well. It can also account for the elemental distributions observed in low-metallicity stars. However, major uncertainties still affect our understanding of the composition of the ejected matter. These concern (i the β-interactions of electron (antineutrinos with free neutrons and protons, as well as their inverse reactions, which may affect the neutron-richness of the matter at the early phase of the ejection, and (ii the nuclear physics of exotic neutron-rich nuclei, including nuclear structure as well as nuclear interaction properties, which impact the calculated abundance distribution. Both aspects are discussed in the light of recent hydrodynamical simulations of NS mergers and microscopic calculations of nuclear decay and reaction probabilities.

  3. Cosmological lepton asymmetry, primordial nucleosynthesis and sterile neutrinos

    Science.gov (United States)

    Abazajian, Kevork; Bell, Nicole F.; Fuller, George M.; Wong, Yvonne Y. Y.

    2005-09-01

    We study post weak decoupling coherent active-sterile and active-active matter-enhanced neutrino flavor transformation in the early Universe. We show that flavor conversion efficiency at Mikheyev-Smirnov-Wolfenstein resonances is likely to be high (adiabatic evolution) for relevant neutrino parameters and energies. However, we point out that these resonances cannot sweep smoothly and continuously with the expansion of the Universe. We show how neutrino flavor conversion in this way can leave both the active and sterile neutrinos with nonthermal energy spectra, and how, in turn, these distorted energy spectra can affect the neutron-to-proton ratio, primordial nucleosynthesis, and cosmological mass/closure constraints on sterile neutrinos. We demonstrate that the existence of a light sterile neutrino which mixes with active neutrinos can change fundamentally the relationship between the cosmological lepton numbers and the primordial nucleosynthesis He4 yield.

  4. Electron capture into the n = 3 states of hydrogen by proton impact on CO, CO2, and N2O

    International Nuclear Information System (INIS)

    Loyd, D.H.; Dawson, H.R.

    1979-01-01

    Absolute cross sections for electron capture into the 3s, 3p, and 3d states of hydrogen have been measured for 2.2--8.2-keV proton impact on CO, CO 2 , and N 2 O. The relative magnitudes of the 3s, 3p, and 3d cross sections for CO are very similar to cross sections previously measured for elemental gases. The CO 2 and N 2 O cross sections have a very different relative distribution among the 3s, 3p, and 3d states compared to all other gases studied in this laboratory, with the 3p cross section being so small that only an estimate of the upper limit to the cross section was possible

  5. Study of isobaric analogue states in 64Zn through proton capture by 63Cu

    International Nuclear Information System (INIS)

    Roy, A.; Iyengar, K.V.K.; Jhingan, M.L.

    1976-01-01

    The reaction 63 Cu(p,γ) 64 Zn has been studied in the proton energy range 1650-2750 keV using the Van de Graaff accelerator at B.A.R.C., Trombay. About 100 resonances were observed in the excitation function out of which the prominent ones at Esub(p)=1731, 1882, 2036, 2099, 2312, 2352, 2421 and 2479 keV have been identified as analogues of the ground and low-lying excited states of 64 Cu. The overall energy resolution was 2.5 keV. The Coulomb displacement energy for the isobaric pair 64 Cu- 64 Zn has been deduced to be 99.63 +- MeV. The spectra of γ-rays and their angular distributions have been obtained at resonances corresponding to the analogue of the ground and first four excited states of 64 Cu. The resonance strengths and the branching ratios for the γ-decay of the resonances has been presented. The M1 width of the γ-decay from resonance at 1751 keV to the ground state of 64 Zn, (0.20 +- 0.04)eV, is in excellent agreement with the value 0.19 eV deduced from the log ft value of 5.3 of the β decay of the parent analogue

  6. Thermal-neutron capture by protons accompanied by e+e- pair production

    International Nuclear Information System (INIS)

    Rekalo, M.P.

    1985-01-01

    Viewing the deuteron as an elementary particle with unit spin and positive spatial parity, we introduce five electromagnetic form factors (three transverse and two longitudinal) characterizing thermal-neutron capture in the reaction n+p→d+e + +e - . All of the observable characteristics of the process n+p→d+e + +e - involving polarized nucleons are calculated in terms of these form factors. The form factors of the transition n+p→d+γ* (γ* is a virtual photon) are related to the nucleon electromagnetic form factors and the characteristics of the dnp vertex using the relativistic impulse approximation. Here only two form factors (one transverse and one longitudinal) turn out to be leading

  7. Heavy-element nucleosynthesis

    International Nuclear Information System (INIS)

    Mathews, G.J.

    1990-01-01

    New measurements and theoretical studies of nuclear properties, together with new astronomical data on the growth of heavy-element abundances during the early history of the Galaxy, now provide a clearer picture of where in nature the elements heavier than iron are produced by rapid (r-process) and show (s-process) neutron capture reactions. The nuclear data suggest that the r-process involves a high-neutron-density beta-flow equilibrium environment and that the s-process may have occurred at a temperature and neutron density consistent with a 13 C(α,n) 16 0 neutron source. The astronomical data, when compared with simple galactic chemical evolution modes, suggests that the r-process is associated with type II supernovae and that the neutron source must be manufactured by the star. Low-mass type II supernovae are proposed as the most important contributors to the r-process. A 13 C neutron source in intermediate-mass stars is proposed for the s-process. 64 refs., 7 figs

  8. Coupled variations of fundamental couplings and primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Coc, Alain; Nunes, Nelson J.; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth

    2006-10-01

    The effect of variations of the fundamental nuclear parameters on big-bang nucleosynthesis are modeled and discussed in detail taking into account the interrelations between the fundamental parameters arising in unified theories. Considering only 4 He, strong constraints on the variation of the neutron lifetime, neutron-proton mass difference are set. These constraints are then translated into constraints on the time variation of the Yukawa couplings and the fine structure constant. Furthermore, we show that a variation of the deuterium binding energy is able to reconcile the 7 Li abundance deduced from the WMAP analysis with its spectroscopically determined value while maintaining concordance with D and 4 He. (authors)

  9. Constraining axion dark matter with Big Bang Nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Blum, Kfir; D' Agnolo, Raffaele Tito [Institute for Advanced Study, Princeton, NJ 08540 (United States); Lisanti, Mariangela; Safdi, Benjamin R. [Department of Physics, Princeton University, Princeton, NJ 08544 (United States)

    2014-10-07

    We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of {sup 4}He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.

  10. Constraining axion dark matter with Big Bang Nucleosynthesis

    Directory of Open Access Journals (Sweden)

    Kfir Blum

    2014-10-01

    Full Text Available We show that Big Bang Nucleosynthesis (BBN significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of He4 during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.

  11. Constraining axion dark matter with Big Bang Nucleosynthesis

    International Nuclear Information System (INIS)

    Blum, Kfir; D'Agnolo, Raffaele Tito; Lisanti, Mariangela; Safdi, Benjamin R.

    2014-01-01

    We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of 4 He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN

  12. Constraining axion dark matter with Big Bang Nucleosynthesis

    Science.gov (United States)

    Blum, Kfir; D'Agnolo, Raffaele Tito; Lisanti, Mariangela; Safdi, Benjamin R.

    2014-10-01

    We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron-proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of 4He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.

  13. Inhomogeneous Big Bang Nucleosynthesis Revisited

    OpenAIRE

    Lara, J. F.; Kajino, T.; Mathews, G. J.

    2006-01-01

    We reanalyze the allowed parameters for inhomogeneous big bang nucleosynthesis in light of the WMAP constraints on the baryon-to-photon ratio and a recent measurement which has set the neutron lifetime to be 878.5 +/- 0.7 +/- 0.3 seconds. For a set baryon-to-photon ratio the new lifetime reduces the mass fraction of He4 by 0.0015 but does not significantly change the abundances of other isotopes. This enlarges the region of concordance between He4 and deuterium in the parameter space of the b...

  14. Proton magnetic resonance spectroscopy of a boron neutron capture therapy 10B-carrier, L-p-boronophenylalanine-fructose complex

    Energy Technology Data Exchange (ETDEWEB)

    Timonen, M.

    2010-07-01

    Boron neutron capture therapy (BNCT) is a radiotherapy that has mainly been used to treat malignant brain tumours, melanomas, and head and neck cancer. In BNCT, the patient receives an intravenous infusion of a 10B-carrier, which accumulates in the tumour area. The tumour is irradiated with epithermal or thermal neutrons, which result in a boron neutron capture reaction that generates heavy particles to damage tumour cells. In Finland, boronophenylalanine fructose (BPA-F) is used as the 10B-carrier. Currently, the drifting of boron from blood to tumour as well as the spatial and temporal accumulation of boron in the brain, are not precisely known. Proton magnetic resonance spectroscopy (1H MRS) could be used for selective BPA-F detection and quantification as aromatic protons of BPA resonate in the spectrum region, which is clear of brain metabolite signals. This study, which included both phantom and in vivo studies, examined the validity of 1H MRS as a tool for BPA detection. In the phantom study, BPA quantification was studied at 1.5 and 3.0 T with single voxel 1H MRS, and at 1.5 T with magnetic resonance imaging (MRSI). The detection limit of BPA was determined in phantom conditions at 1.5 T and 3.0 T using single voxel 1H MRS, and at 1.5 T using MRSI. In phantom conditions, BPA quantification accuracy of +- 5% and +- 15% were achieved with single voxel MRS using external or internal (internal water signal) concentration references, respectively. For MRSI, a quantification accuracy of <5% was obtained using an internal concentration reference (creatine). The detection limits of BPA in phantom conditions for the PRESS sequence were 0.7 (3.0 T) and 1.4 mM (1.5 T) mM with 20 x 20 single voxel MRS, and 1.0 mM with acquisition-weighted MRSI, respectively. In the in vivo study, an MRSI or single voxel MRS or both was performed for ten patients (patients 1-10) on the day of BNCT. Three patients had glioblastoma multiforme (GBM), and five patients had a recurrent or

  15. Electron capture into the 3s, 3p, 3d states and the 3, 4, 5, 6 levels of H by proton impact on gases

    International Nuclear Information System (INIS)

    Lenormand, J.

    1976-01-01

    The excitation of the Hsub(α), Hsub(β), Hsub(γ), Hsub(delta) Balmer lines by means of 15-85keV protons incident on noble-gas and molecular targets have been observed. Absolute cross-sections for electron capture by the 3l (l=s, p, d) states and the 3, 4, 5, 6 levels of hydrogen atom have been determined with He, Ne, Ar, Kr, Xe, N 2 and O 2 . Polarizations of the Hsub(α) and Hsub(β) lines have been measured for 10-70keV protons on Ar, Kr, and Xe. Absolute cross-sections for the emission of the 3914A band of N 2 + have been obtained for 10-100keV protons on the gaseous nitrogen target [fr

  16. Spallation nucleosynthesis by accelerated charged-particles

    International Nuclear Information System (INIS)

    Goriely, S.

    2008-01-01

    Recent observations have suggested the presence of radioactive elements, such as Pm and 84≤Z≤99 elements) at the surface of the magnetic star HD101065, also known as Przybylski's star. This star is know to be a chemically peculiar star and its anomalous 38 30 heavy elements can be achieved. In this nucleosynthesis process, the secondary-neutron captures play a crucial role. The most attractive feature of the spallation process is the systematic production of Pm and Tc and the possible synthesis of actinides and sub-actinides.Based on such a parametric model, it is also shown that intense fluences of accelerated charged-particles interacting with surrounding material can efficiently produce elements heavier than iron. Different regimes are investigated and shown to be at the origin of p- and s-nuclei in the case of high-fluence low-flux events and r-nuclei for high-fluence high-flux irradiations. The possible existence of such irradiation events need to be confirmed by hydrodynamics simulations, but most of all by spectroscopic observations through the detection of short-lived radio-elements

  17. Primordial nucleosynthesis: Beyond the standard model

    International Nuclear Information System (INIS)

    Malaney, R.A.

    1991-01-01

    Non-standard primordial nucleosynthesis merits continued study for several reasons. First and foremost are the important implications determined from primordial nucleosynthesis regarding the composition of the matter in the universe. Second, the production and the subsequent observation of the primordial isotopes is the most direct experimental link with the early (t approx-lt 1 sec) universe. Third, studies of primordial nucleosynthesis allow for important, and otherwise unattainable, constraints on many aspects of particle physics. Finally, there is tentative evidence which suggests that the Standard Big Bang (SBB) model is incorrect in that it cannot reproduce the inferred primordial abundances for a single value of the baryon-to-photon ratio. Reviewed here are some aspects of non-standard primordial nucleosynthesis which mostly overlap with the authors own personal interest. He begins with a short discussion of the SBB nucleosynthesis theory, high-lighting some recent related developments. Next he discusses how recent observations of helium and lithium abundances may indicate looming problems for the SBB model. He then discusses how the QCD phase transition, neutrinos, and cosmic strings can influence primordial nucleosynthesis. He concludes with a short discussion of the multitude of other non-standard nucleosynthesis models found in the literature, and make some comments on possible progress in the future. 58 refs., 7 figs., 2 tabs

  18. Long-Range Electrostatics-Induced Two-Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site.

    Science.gov (United States)

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen-Hsiang; Parks, Jerry M; Smith, Jeremy C; Weiss, Kevin L; Keen, David A; Blakeley, Matthew P; Louis, John M; Langan, Paul; Weber, Irene T; Kovalevsky, Andrey

    2016-04-11

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. From (p)reheating to nucleosynthesis

    International Nuclear Information System (INIS)

    Jedamzik, Karsten

    2002-01-01

    This paper gives a brief qualitative description of the possible evolution of the early universe between the end of an inflationary epoch and the end of big-bang nucleosynthesis. After a general introduction, establishing the minimum requirements cosmologists impose on this cosmic evolutionary phase, namely, successful baryogenesis, the production of cosmic dark matter and successful light-element nucleosynthesis, a more detailed discussion on some recent developments follows. This latter includes the physics of preheating, the putative production of (alternative) dark matter and the current status of big bang nucleosynthesis

  20. Late baryogenesis faces primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Delbourgo-Salvador, P.; Audouze, J.; Salati, P.

    1991-11-01

    Since the sphalleron mechanism present in the standard theory of electro-weak interactions violates B+L, models have been suggested where baryogenesis takes place at late epochs and is concomitant with primordial nucleosynthesis. The possibility for the baryon asymmetry to be generated was numerically investigated at the same time as the light elements are cooked. The primordial yields of D, 3 He, 4 He and 7 Li were shown to exceed the upper limits inferred from observation, unless baryogenesis is anterior to the freeze-out of the weak interactions. This implies strong constraints on scenarios where the baryon asymmetry originates from the late decay of massive gravitinos. (author) 18 refs., 6 figs

  1. Nucleosynthesis in Jets from Collapsars

    International Nuclear Information System (INIS)

    Fujimoto, Shin-ichiro; Nishimura, Nobuya; Hashimoto, Masa-aki

    2008-01-01

    We investigate nucleosynthesis inside magnetically driven jets ejected from collapsars, or rotating magnetized stars collapsing to a black hole, based on two-dimensional magnetohydrodynamic simulation of the collapsars during the core collapse. We follow the evolution of the abundances of about 4000 nuclides from the collapse phase to the ejection phase using a large nuclear reaction network. We find that the r-process successfully operates only in the energetic jets (>10 51 erg), so that U and Th are synthesized abundantly, even when the collapsars have a relatively small magnetic field (10 10 G) and a moderately rotating core before the collapse. The abundance patterns inside the jets are similar to that of the r-elements in the solar system. The higher energy jets have larger amounts of 56 Ni. Less energetic jets, which have small amounts of 56 Ni, could induce GRB without supernova, such as GRB060505 and GRB060614

  2. Big Bang nucleosynthesis in crisis?

    International Nuclear Information System (INIS)

    Hata, N.; Scherrer, R.J.; Steigman, G.; Thomas, D.; Walker, T.P.; Bludman, S.; Langacker, P.

    1995-01-01

    A new evaluation of the constraint on the number of light neutrino species (N ν ) from big bang nucleosynthesis suggests a discrepancy between the predicted light element abundances and those inferred from observations, unless the inferred primordial 4 He abundance has been underestimated by 0.014±0.004 (1σ) or less than 10% (95% C.L.) of 3 He survives stellar processing. With the quoted systematic errors in the observed abundances and a conservative chemical evolution parametrization, the best fit to the combined data is N ν =2.1±0.3 (1σ) and the upper limit is N ν ν =3) at the 98.6% C.L. copyright 1995 The American Physical Society

  3. On the idea of low-energy nuclear reactions in metallic lattices by producing neutrons from protons capturing "heavy" electrons

    Science.gov (United States)

    Tennfors, Einar

    2013-02-01

    The present article is a critical comment on Widom and Larsens speculations concerning low-energy nuclear reactions (LENR) based on spontaneous collective motion of protons in a room temperature metallic hydride lattice producing oscillating electric fields that renormalize the electron self-energy, adding significantly to the effective electron mass and enabling production of low-energy neutrons. The frequency and mean proton displacement estimated on the basis of neutron scattering from protons in palladium and applied to the Widom and Larsens model of the proton oscillations yield an electron mass enhancement less than one percent, far below the threshold for the proposed neutron production and even farther below the mass enhancement obtained by Widom and Larsen assuming a high charge density. Neutrons are not stopped by the Coulomb barrier, but the energy required for the neutron production is not low.

  4. Cosmic-Ray Nucleosynthesis of p-nuclei: Yields and Routes

    Science.gov (United States)

    Kusakabe, Motohiko; Mathews, Grant J.

    2018-02-01

    We investigate the cosmic-ray nucleosynthesis (CRN) of proton-rich stable nuclides (p-nuclides). We calculate the cosmic-ray (CR) energy spectra of heavy nuclides with mass number A=[74,209], taking into account the detailed nuclear spallation, decay, energy loss, and escape from the Galaxy during the CR propagation. We adopt the latest semiempirical formula SPACS for the spallation cross sections and the latest data on nuclear decay. Effective electron-capture decay rates are calculated using the proper cross sections for recombination and ionization in the whole CR energy region. Calculated CR spectral shapes vary for different nuclides. Abundances of proton-rich unstable nuclides increase in CRs with increasing energy relative to those of other nuclides. Yields of the primary and secondary spallation processes and differential yields from respective seed nuclides are calculated. We find that the CR energy region of ≤slant { \\mathcal O }(100) MeV/nucleon predominantly contributes to the total yields. The atomic cross sections in the low-energy range adopted in this study are then necessary. Effects of CRN on the Galactic chemical evolution of p-nuclides are calculated. Important seed nuclides are identified for respective p-nuclides. The contribution of CRN is significant for 180m Ta, accounting for about 20% of the solar abundance. About 87% of the 180m Ta CRN yield can be attributed to the primary process. The most important production routes are reactions of 181Ta, 180Hf, and 182W. CRN yields of other p-nuclides are typically about { \\mathcal O }(10‑4–10‑2) of solar abundances.

  5. The role of nuclear inputs in r-process nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Giuliani, Samuel Andrea; Arzhanov, Alexander; Friess, Stephen; Martinez-Pinedo, Gabriel; Moeller, Heiko; Sieverding, Andre; Wu, Meng-Ru [TU Darmstadt (Germany)

    2016-07-01

    We have studied the sensitivity of the r-process abundances produced in dynamical ejecta from neutron star mergers to different nuclear mass models. For each mass model, the resulting abundances are almost independent of the astrophysical conditions and reproduce the general features of the observed r-process abundance. We find that the second peak around A ∝ 130 is produced by the fission yields of the material that piles up in nuclei with A >or similar 250. We also find distinct differences in the predictions at and just above the third peak (A ∝ 195) for different mass models, due to different neutron separation energies at N = 130. Due to the crucial role that fission plays in r-process nucleosynthesis, we have computed the fission properties of superheavy nuclei using the BCPM energy density functional. We found that certain combinations of neutron and proton number lead to an enhanced stability against the spontaneous fission process, related with the existence of magic numbers in the superheavy region. However, the systematic of the fission properties is strongly affected by the choice of the collective degree of freedom when the fission path is obtained by minimizing the action integral. Finally, a comparison with other theoretical models and the consequences for r-process nucleosynthesis are discussed.

  6. Big-bang nucleosynthesis revisited

    Science.gov (United States)

    Olive, Keith A.; Schramm, David N.; Steigman, Gary; Walker, Terry P.

    1989-01-01

    The homogeneous big-bang nucleosynthesis yields of D, He-3, He-4, and Li-7 are computed taking into account recent measurements of the neutron mean-life as well as updates of several nuclear reaction rates which primarily affect the production of Li-7. The extraction of primordial abundances from observation and the likelihood that the primordial mass fraction of He-4, Y(sub p) is less than or equal to 0.24 are discussed. Using the primordial abundances of D + He-3 and Li-7 we limit the baryon-to-photon ratio (eta in units of 10 exp -10) 2.6 less than or equal to eta(sub 10) less than or equal to 4.3; which we use to argue that baryons contribute between 0.02 and 0.11 to the critical energy density of the universe. An upper limit to Y(sub p) of 0.24 constrains the number of light neutrinos to N(sub nu) less than or equal to 3.4, in excellent agreement with the LEP and SLC collider results. We turn this argument around to show that the collider limit of 3 neutrino species can be used to bound the primordial abundance of He-4: 0.235 less than or equal to Y(sub p) less than or equal to 0.245.

  7. Neutrinos and Big Bang Nucleosynthesis

    Directory of Open Access Journals (Sweden)

    Gary Steigman

    2012-01-01

    Full Text Available According to the standard models of particle physics and cosmology, there should be a background of cosmic neutrinos in the present Universe, similar to the cosmic microwave photon background. The weakness of the weak interactions renders this neutrino background undetectable with current technology. The cosmic neutrino background can, however, be probed indirectly through its cosmological effects on big bang nucleosynthesis (BBN and the cosmic microwave background (CMB radiation. In this BBN review, focused on neutrinos and more generally on dark radiation, the BBN constraints on the number of “equivalent neutrinos” (dark radiation, on the baryon asymmetry (baryon density, and on a possible lepton asymmetry (neutrino degeneracy are reviewed and updated. The BBN constraints on dark radiation and on the baryon density following from considerations of the primordial abundances of deuterium and helium-4 are in excellent agreement with the complementary results from the CMB, providing a suggestive, but currently inconclusive, hint of the presence of dark radiation, and they constrain any lepton asymmetry. For all the cases considered here there is a “lithium problem”: the BBN-predicted lithium abundance exceeds the observationally inferred primordial value by a factor of ~3.

  8. Supernova neutrinos and explosive nucleosynthesis

    Science.gov (United States)

    Kajino, T.; Aoki, W.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Mathews, G. J.; Nakamura, K.; Shibagaki, S.; Suzuki, T.

    2014-05-01

    Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes 7Li, 11B, 92Nb, 138La and 180Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and θ13, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements 11B and 7Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ13, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

  9. Supernova neutrinos and explosive nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kajino, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Aoki, W. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Hayakawa, T. [Japan Atomic Energy Agency, Shirakara-Shirane 2-4, Tokai-mura, Ibaraki 319-1195 (Japan); Hidaka, J.; Hirai, Y.; Shibagaki, S. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Nakamura, K. [Faculty of Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Suzuki, T. [Department of Physics, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan)

    2014-05-09

    Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and θ{sub 13}, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements {sup 11}B and {sup 7}Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ{sub 13}, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

  10. Deuterium and big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Burles, S.

    2000-01-01

    Measurements of deuterium absorption in high redshift quasar absorption systems provide a direct inference of the deuterium abundance produced by big bang nucleosynthesis (BBN). With measurements and limits from five independent absorption systems, we place strong constraints on the primordial ratio of deuterium to hydrogen, (D/H) p = 3.4 ± 0.3 x 10 -5 [1,2]. We employ a direct numerical treatment to improve the estimates of critical reaction rates and reduce the uncertainties in BBN predictions of D/H and 7 Li/H by a factor of three[3] over previous efforts[4]. Using our measurements of (D/H) p and new BBN predictions, we find at 95% confidence the baryon density ρ b = (3.6 ± 0.4) x 10 -31 g cm -3 (Ω b h 2 65 = 0.045 ± 0.006 in units of the critical density), and cosmological baryon-photon ratio η = (5.1 ± 0.6) x 10 -10

  11. Evolution and nucleosynthesis of asymptotic giant branch stellar models of low metallicity

    Energy Technology Data Exchange (ETDEWEB)

    Fishlock, Cherie K.; Karakas, Amanda I.; Yong, David [Research School of Astronomy and Astrophysics, Australian National University, Canberra ACT 2611 (Australia); Lugaro, Maria, E-mail: cherie.fishlock@anu.edu.au, E-mail: amanda.karakas@anu.edu.au, E-mail: david.yong@anu.edu.au, E-mail: maria.lugaro@monash.edu [Monash Centre for Astrophysics, Monash University, Clayton VIC 3800 (Australia)

    2014-12-10

    We present stellar evolutionary tracks and nucleosynthetic predictions for a grid of stellar models of low- and intermediate-mass asymptotic giant branch (AGB) stars at Z = 0.001 ([Fe/H] =–1.2). The models cover an initial mass range from 1 M {sub ☉} to 7 M {sub ☉}. Final surface abundances and stellar yields are calculated for all elements from hydrogen to bismuth as well as isotopes up to the iron group. We present the first study of neutron-capture nucleosynthesis in intermediate-mass AGB models, including a super-AGB model, of [Fe/H] = –1.2. We examine in detail a low-mass AGB model of 2 M {sub ☉} where the {sup 13}C(α,n){sup 16}O reaction is the main source of neutrons. We also examine an intermediate-mass AGB model of 5 M {sub ☉} where intershell temperatures are high enough to activate the {sup 22}Ne neutron source, which produces high neutron densities up to ∼10{sup 14} n cm{sup –3}. Hot bottom burning is activated in models with M ≥ 3 M {sub ☉}. With the 3 M {sub ☉} model, we investigate the effect of varying the extent in mass of the region where protons are mixed from the envelope into the intershell at the deepest extent of each third dredge-up. We compare the results of the low-mass models to three post-AGB stars with a metallicity of [Fe/H] ≅ – 1.2. The composition is a good match to the predicted neutron-capture abundances except for Pb and we confirm that the observed Pb abundances are lower than what is calculated by AGB models.

  12. Circular polarization of γ-quanta radiated in the capture of polarized neutrons by protons and the quark compound bag model

    International Nuclear Information System (INIS)

    Grach, I.L.; Shmatkov, M.Zh.

    1983-01-01

    The circular polarization Psub(γ) of γ-quanta radiated in the capture of polarized neutrons by protons is calculated The contribution of the M1 and E2 radiation of nucleons to Psub(γ) is found using the accurate wave functions of the continuous spectrum. The contribution of the six-quark bag to the polarization Psub(γ) is determined. The value of Psub(γ) is related to the admixture of the 6q-bag in the deuteron. Experimental value of Psub(γ) corresponds to small (< or approximately 0.7%) admixture of the bag

  13. Nucleosynthesis and the nova outburst

    International Nuclear Information System (INIS)

    Starrfield, S.

    1995-01-01

    A nova outburst is the consequence of the accretion of hydrogen rich material onto a white dwarf and it can be considered as the largest hydrogen bomb in the Universe. The fuel is supplied by a secondary star in a close binary system while the strong degeneracy of the massive white dwarf acts to contain the gas during the early stages of the explosion. The containment allows the temperature in the nuclear burning region to exceed 10 8 K under all circumstances. As a result a major fraction of CNO nuclei in the envelope are transformed into β + -unstable nuclei. We discuss the effects of these nuclei on the evolution. Recent observational studies have shown that there are two compositional classes of novae; one which occurs on carbon-oxygen white dwarfs, and a second class that occurs on oxygen-neon-magnesium white dwarfs. In this review we will concentrate on the latter explosions since they produce the most interesting nucleosynthesis. We report both on the results of new observational determinations of nova abundances and, in addition, new hydrodynamic calculations that examine the consequences of the accretion process on 1.0M circle-dot , 1.25M circle-dot , and 1.35M circle-dot white dwarfs. Our results show that novae can produce 22 Na, 26 Al, and other intermediate mass nuclei in interesting amounts. We will present the results of new calculations, done with updated nuclear reaction rates and opacities, which exhibit quantitative differences with respect to published work

  14. Primordial nucleosynthesis: A cosmological point of view

    International Nuclear Information System (INIS)

    Mathews, G. J.; Kajino, T.; Yamazaki, D.; Kusakabe, M.; Cheoun, M.-K.

    2014-01-01

    Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the test-ing ground upon which all cosmological models must ultimately rest. It is our only probe of the universe during the first few minutes of cosmic expansion and in particular during the important radiation-dominated epoch. These lectures review the basic equations of space-time, cosmology, and big bang nucleosynthesis. We will then review the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measure-ments are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we summarize the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field

  15. Polarized proton capture reaction /sup 7/Li(p,. gamma. )/sup 8/Be in the energy range from 380 to 960 keV

    Energy Technology Data Exchange (ETDEWEB)

    Ulbricht, J; Arnold, W; Berg, H; Huttel, E; Krause, H H; Clausnitzer, G [Giessen Univ. (Germany, F.R.). Abt. Grossgeraete (Angewandte Kernphysik)

    1977-09-05

    The polarized proton capture in /sup 7/Li was used to study the reaction mechanism and to obtain spectroscopic information on the /sup 8/Be nucleus. Gamma-ray angular distributions of the analyzing power were measured as a function of proton energy from Esub(p) = 380-960 keV with three Ge(Li) detectors simultaneously. The excitation functions of the cross section and the analyzing power are strongly energy dependent. The data were analyzed unambiguously and represented by three R-matrix elements, two M1 and one E1. The energy dependence of the two M1 matrix elements agrees with the well-known two 1/sup +/ resonances at Esub(x) = 17.642 and 18.157 MeV. The energy dependence of the E1 matrix element shows a smooth background presumably caused by a direct-capture mechanism, and furthermore, a resonant contribution, which is a significant suggestion of a new 1/sup -/ state in the /sup 8/Be system at Esub(x) = 17.70 MeV with a width of GAMMAsub(p) = 180 keV.

  16. Shifting of the electron-capture-to-the-continuum peak in proton-helium collisions at 10 and 20 keV

    International Nuclear Information System (INIS)

    Bhattacharya, S.; Deb, N.C.; Roy, K.; Sahoo, S.; Crothers, D.S.F.

    2005-01-01

    A refined theoretical approach has been developed to study the double-differential cross sections (DDCS's) in proton-helium collisions as a function of the ratio of ionized electron velocity to the incident proton velocity. The refinement is done in the present coupled-channel calculation by introducing a continuum distorted wave in the final state coupled with discrete states including direct as well as charge transfer channels. It is confirmed that the electron-capture-to-the-continuum (ECC) peak is slightly shifted to a lower electron velocity than the equivelocity position. Comparing measurements and classical trajectory Monte Carlo (CTMC) calculations at 10 and 20 keV proton energies, excellent agreement of the ECC peak heights is achieved at both energies. However, a minor disagreement in the peak positions between the present calculation and the CTMC results is noted. A smooth behavior of the DDCS is found in the present calculation on both sides of the peak whereas the CTMC results show some oscillatory behavior particularly to the left of the peak, associated with the statistical nature of CTMC calculations

  17. Nucleosynthesis in cold white dwarf explosions

    International Nuclear Information System (INIS)

    Canal, R.; Hernanz, M.

    1986-01-01

    Type I supernovae (SNI) are generally thought to be the main contributors to the galactic nucleosynthesis of iron-peak elements and their yields of intermediate-mass elements may also be important. We concentrate here upon a different class of models, based on the explosion of cold, massive, partially solid white dwarfs. We show that such white dwarfs must be relatively frequent among SNI progenitors and how their hydrodynamics upon ignition is very different from that of hotter, fluid white dwarfs. The implications for nucleosynthesis are briefly discussed and some preliminary results are presented

  18. Explosive Nucleosynthesis in Different Ye Conditions

    International Nuclear Information System (INIS)

    Iwamoto, Nobuyuki; Umeda, Hideyuki; Nomoto, Ken'ichi; Tominaga, Nozomu; Thielemann, Friedrich-Karl; Hix, W. Raphael

    2006-01-01

    The influence of a large variation of Ye on explosive yield is investigated. We calculate nucleosynthesis with the initial electron fraction Ye ranging from 0.48 to 0.58 in explosive Si burning region in Population III, 25 M· supernovae. We obtain the significant overproduction of odd elements, K and Sc. In the Ye < 0.5 cases light p-process nuclei are enhanced. We find that the abundance pattern taken from arbitrary mixture of each nucleosynthesis yield in various values of Ye can reasonably explain that in observed extremely metal-poor stars

  19. Neutral currents, supernovae neutrinos, and nucleosynthesis

    International Nuclear Information System (INIS)

    Haxton, W.C.

    1988-01-01

    The inelastic interactions of neutrinos during stellar collapse and neutron star cooling are discussed. The primary mechanism for dissipative neutrino reactions is nuclear excitation by neutral current scattering, a process not included in standard descriptions of supernovae. Charge-current and neutral current ''preheating'' of iron lying outside the shock front appears to be significant in the few milliseconds near shock breakout. This could help produce a more energetic shock. During the cooling phase, the neutral current interactions of muon and taon neutrinos appear to be responsible for some interesting nucleosynthesis. I discuss two examples the production of fluorine and neutrino-induced r-process nucleosynthesis. 26 refs., 1 fig., 3 tabs

  20. Big bang nucleosynthesis - Predictions and uncertainties

    International Nuclear Information System (INIS)

    Krauss, L.M.; Romanelli, P.

    1990-01-01

    A detailed reexamination is made of primordial big-bang nucleosynthesis (BBN), concentrating on the data for the main nuclear reactions leading to the production of Li-7, He-3 and D, and on the neutron half-life, relevant for He-4 production. The new values for reaction rates and uncertainties are then used as input in a Monte Carlo analysis of big bang nucleosynthesis of light elements. This allows confidence levels for the predictions of the standard BBN model to be high. 70 refs

  1. Big bang nucleosynthesis constraints on bulk neutrinos

    International Nuclear Information System (INIS)

    Goh, H.S.; Mohapatra, R.N.

    2002-01-01

    We examine the constraints imposed by the requirement of successful nucleosynthesis on models with one large extra hidden space dimension and a single bulk neutrino residing in this dimension. We solve the Boltzmann kinetic equation for the thermal distribution of the Kaluza-Klein modes and evaluate their contribution to the energy density at the big bang nucleosynthesis epoch to constrain the size of the extra dimension R -1 ≡μ and the parameter sin 2 2θ which characterizes the mixing between the active and bulk neutrinos

  2. Proton-rich nuclear statistical equilibrium

    International Nuclear Information System (INIS)

    Seitenzahl, I.R.; Timmes, F.X.; Marin-Lafleche, A.; Brown, E.; Magkotsios, G.; Truran, J.

    2008-01-01

    Proton-rich material in a state of nuclear statistical equilibrium (NSE) is one of the least studied regimes of nucleosynthesis. One reason for this is that after hydrogen burning, stellar evolution proceeds at conditions of an equal number of neutrons and protons or at a slight degree of neutron-richness. Proton-rich nucleosynthesis in stars tends to occur only when hydrogen-rich material that accretes onto a white dwarf or a neutron star explodes, or when neutrino interactions in the winds from a nascent proto-neutron star or collapsar disk drive the matter proton-rich prior to or during the nucleosynthesis. In this Letter we solve the NSE equations for a range of proton-rich thermodynamic conditions. We show that cold proton-rich NSE is qualitatively different from neutron-rich NSE. Instead of being dominated by the Fe-peak nuclei with the largest binding energy per nucleon that have a proton-to-nucleon ratio close to the prescribed electron fraction, NSE for proton-rich material near freezeout temperature is mainly composed of 56Ni and free protons. Previous results of nuclear reaction network calculations rely on this nonintuitive high-proton abundance, which this Letter explains. We show how the differences and especially the large fraction of free protons arises from the minimization of the free energy as a result of a delicate competition between the entropy and nuclear binding energy.

  3. A Measurement of the Rate of Muon Capture in Hydrogen Gas andDetermination of the Proton's Induced Pseudoscalar Coupling gP

    Energy Technology Data Exchange (ETDEWEB)

    Banks, Thomas Ira [Univ. of California, Berkeley, CA (United States)

    2007-07-01

    This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between the μ- disappearance rate in hydrogen--as determinedfrom data collected in the experiment's first physics run in fall2004--and the world averagefor the μ+ decay rate. After combining theresults of my analysis with the results from another independent analysisof the 2004 data, the muon capture rate from the hyperfine singlet groundstate of the mu-p atom is found to be ΛS = 725.0 ± 17.4 1/s, fromwhich the induced pseudoscalar coupling of the nucleon, gP(q2 = -0.88m$2\\atop{μ}$)= 7.3 ± 1.1, is extracted. This result for gP is consistent withtheoretical predictions that are based on the approximate chiral symmetryof QCD.

  4. Large-basis shell-model technology in nucleosynthesis and cosmology

    International Nuclear Information System (INIS)

    Mathews, G.J.; Bloom, S.D.; Takahashi, K.; Fuller, G.M.; Hausman, R.F. Jr.

    1985-05-01

    We discuss various applications of the Lanczos method to describe properties of many-body microscopic systems in nucleosynthesis and cosmology. These calculations include: solar neutrino detectors; beta-decay of excited nuclear states; electron-capture rates during a core-bounce supernova; exotic quarked nuclei as a catalyst for hydrogen burning; and the quark-hadron phase transition during the early universe. 27 refs., 3 figs

  5. Study of the supernova nucleosynthesis 40Ca(α,γ)44Ti reaction: progress report

    International Nuclear Information System (INIS)

    Nassar, H.; Paul, M.; Ghelberg, S.; Ofan, A.; Trubnikov, N.; Ben-Dov, Y.; Hass, M.; Nara Singh, B.S.

    2005-01-01

    We report on a study of the α-capture reaction on 40 Ca in the energy range relevant to supernova nucleosynthesis (T 9 ∼ 0.8-3). The experiment measures the overall yield of 44 Ti nuclei produced in an activation of a thick 4 He target by a 40 Ca beam. Preliminary results show a significantly stronger yield than observed in previous measurements in the range T 9 ∼ 1.5-3

  6. THE INTERMEDIATE NEUTRON-CAPTURE PROCESS AND CARBON-ENHANCED METAL-POOR STARS

    Energy Technology Data Exchange (ETDEWEB)

    Hampel, Melanie [Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, D-69117 Heidelberg (Germany); Stancliffe, Richard J. [Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, D-53121 Bonn (Germany); Lugaro, Maria [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, H-1121 Budapest (Hungary); Meyer, Bradley S., E-mail: mhampel@lsw.uni-heidelberg.de [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 (United States)

    2016-11-10

    Carbon-enhanced metal-poor (CEMP) stars in the Galactic Halo display enrichments in heavy elements associated with either the s (slow) or the r (rapid) neutron-capture process (e.g., barium and europium, respectively), and in some cases they display evidence of both. The abundance patterns of these CEMP- s / r stars, which show both Ba and Eu enrichment, are particularly puzzling, since the s and the r processes require neutron densities that are more than ten orders of magnitude apart and, hence, are thought to occur in very different stellar sites with very different physical conditions. We investigate whether the abundance patterns of CEMP- s / r stars can arise from the nucleosynthesis of the intermediate neutron-capture process (the i process), which is characterized by neutron densities between those of the s and the r processes. Using nuclear network calculations, we study neutron capture nucleosynthesis at different constant neutron densities n ranging from 10{sup 7}–10{sup 15} cm{sup -3}. With respect to the classical s process resulting from neutron densities on the lowest side of this range, neutron densities on the highest side result in abundance patterns, which show an increased production of heavy s -process and r -process elements, but similar abundances of the light s -process elements. Such high values of n may occur in the thermal pulses of asymptotic giant branch stars due to proton ingestion episodes. Comparison to the surface abundances of 20 CEMP- s / r stars shows that our modeled i -process abundances successfully reproduce observed abundance patterns, which could not be previously explained by s -process nucleosynthesis. Because the i -process models fit the abundances of CEMP- s / r stars so well, we propose that this class should be renamed as CEMP- i .

  7. np→dγ for big-bang nucleosynthesis

    International Nuclear Information System (INIS)

    Chen, Jiunn-Wei; Savage, Martin J.

    1999-01-01

    The cross section for np→dγ is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The E1 amplitude is computed up to N 3 LO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is computed up to next-to-leading order, and the four-nucleon-one-magnetic-photon counterterm that enters is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to E∼1 MeV is estimated to be (less-or-similar sign)4%. (c) 1999 The American Physical Society

  8. Fred Hoyle, primary nucleosynthesis and radioactivity

    Science.gov (United States)

    Clayton, Donald D.

    2008-10-01

    Primary nucleosynthesis is defined as that which occurs efficiently in stars born of only H and He. It is responsible not only for increasing the metallicity of the galaxy but also for the most abundant gamma-ray-line emitters. Astrophysicists have inappropriately cited early work in this regard. The heavily cited B2FH paper (Burbidge et al., 1957) did not effectively address primary nucleosynthesis whereas Hoyle (Hoyle, 1954) had done so quite thoroughly in his infrequently cited 1954 paper. Even B2FH with Hoyle as coauthor seems strangely to not have appreciated what Hoyle (Hoyle, 1954) had achieved. I speculate that Hoyle must not have thoroughly proofread the draft written in 1956 by E.M. and G.R. Burbidge. The clear roadmap of primary nucleosynthesis advanced in 1954 by Hoyle describes the synthesis yielding the most abundant of the radioactive isotopes for astronomy, although that aspect was unrealized at the time. Secondary nucleosynthesis has also produced many observable radioactive nuclei, including the first gamma-ray-line emitter to be discovered in the galaxy and several others within stardust grains. Primary gamma-ray emitters would have been even more detectable in the early galaxy, when the birth rate of massive stars was greater; but secondary emitters, such as 26Al, would have been produced with smaller yield then owing to smaller abundance of seed nuclei from which to create them.

  9. Beta decay and muon capture rates in a self-consistent relativistic framework

    Energy Technology Data Exchange (ETDEWEB)

    Marketin, Tomislav; Paar, Nils; Niksic, Tamara; Vretenar, Dario [Physics Department, Faculty of Science, University of Zagreb (Croatia); Ring, Peter [Physik-Department, Technische Universitaet Muenchen, D-85748 Muenchen (Germany)

    2009-07-01

    A fully consistent calculation of muon capture and beta decay rates is presented, based on a microscopic theoretical framework describing the semileptonic weak interaction processes. Nuclear ground state is determined using the Relativistic Hartree-Bogolyubov (RHB) model with density dependent meson-nucleon coupling constants, and transition rates are calculated via proton-neutron relativistic quasiparticle RPA using the same interaction as in the RHB equations. Muon capture rates are calculated for a wide range of nuclei along the valley of stability, from {sup 12}C to {sup 244}Pu, with accuracy of approximately 30%, using the interaction DD-ME2. Previous studies of beta decay rates have only taken into account Gamow-Teller transitions. We extend this approach by including forbidden transitions and systematically study their contribution to decay rates of exotic nuclei along the r-process path, which are important for constraining the conditions in which nucleosynthesis takes place.

  10. Consistency of neutron and proton capture intensity standards new relative intensities for 56Co, 66Ga decay and 35Cl(n,γ) reaction gamma rays

    International Nuclear Information System (INIS)

    Molnar, G.L.; Revay, Z.; Belgya, T.

    2000-01-01

    The equivalence of efficiency determination procedures based on neutron and proton capture lines has been verified and the deviation of high-energy efficiency from linearity confirmed. The new, accurate relative intensities for 56 Co and 66 Ga extend the range of secondary radioactive standards up to 4.8 MeV. Extreme care has to be taken with any high-energy intensity value obtained in the past with the help of 56 Co and 66 Ga calibration sources, and corrections have to be made using the present data of high accuracy. Relative intensities have also been improved for the 35 Cl(n,γ) reaction, a useful secondary standard in a wide energy range, between 0.3-8.5 MeV. The new data are supported by other most recent measurements of a slightly lower precision

  11. Sensitivity tests on the rates of the excited states of positron decays during the rapid proton capture process of the one-zone X-ray burst model

    Science.gov (United States)

    Lau, Rita

    2018-02-01

    In this paper, we investigate the sensitivities of positron decays on a one-zone model of type-I X-ray bursts. Most existing studies have multiplied or divided entire beta decay rates (electron captures and beta decay rates) by 10. Instead of using the standard Fuller & Fowler (FFNU) rates, we used the most recently developed weak library rates [1], which include rates from Langanke et al.'s table (the LMP table) (2000) [2], Langanke et al.'s table (the LMSH table) (2003) [3], and Oda et al.'s table (1994) [4] (all shell model rates). We then compared these table rates with the old FFNU rates [5] to study differences within the final abundances. Both positron decays and electron capture rates were included in the tables. We also used pn-QRPA rates [6,7] to study the differences within the final abundances. Many of the positron rates from the nuclei's ground states and initial excited energy states along the rapid proton capture (rp) process have been measured in existing studies. However, because temperature affects the rates of excited states, these studies should have also acknowledged the half-lives of the nuclei's excited states. Thus, instead of multiplying or dividing entire rates by 10, we studied how the half-lives of sensitive nuclei in excited states affected the abundances by dividing the half-lives of the ground states by 10, which allowed us to set the half-lives of the excited states. Interestingly, we found that the peak of the final abundance shifted when we modified the rates from the excited states of the 105Sn positron decay rates. Furthermore, the abundance of 80Zr also changed due to usage of pn-QRPA rates instead of weak library rates (the shell model rates).

  12. Current rate of nucleosynthesis and its implications

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, D C.V.

    1981-06-01

    Comparisons among stellar birthrate figures for stars of 05-9 and B0, 0.5 and 1 spectral type show that the current rate of nucleosynthesis is compatible with the idea of massive stars producing most of the metals only in the event that the stellar birthrate decreased with time. The current stellar evolution data, as well as observations, do not support the premise that intermediate mass stars are the source of the bulk of the nucleosynthesis in the galaxy. It is concluded that the limits of the Simple Model must be surpassed with the supposition of prompt initial enrichment, in order foo the stellar birthrate to be constant while the metals originate in the massive stars.

  13. Type Ia Supernovae: Energetics, Neutronization and Nucleosynthesis

    International Nuclear Information System (INIS)

    Truran, James W.; Calder, Alan C.; Townsley, Dean M.; Seitenzahl, Ivo R.; Peng, Fang; Vladimirova, Natalia; Lamb, Donald Q.; Brown, Edward F.

    2007-01-01

    The utility of Type Ia supernovae, not simply as probes of the distance scale but also as a means of constraining the properties of dark energy, demands a significant improvement in theoretical predictions of their properties in outburst. To this end, we have given substantial effort to quantifying the energetics and nucleosynthesis properties of deflagration fronts in the interiors of the putative carbon-oxygen white dwarf progenitors of Type Ia thermonuclear supernovae. We briefly review some essential features of our flame model and its properties in this paper and discuss its implications both for our multidimensional numerical simulations of SNe Ia and for nucleosynthesis (specifically 56Ni production) in SNe Ia and Galactic chemical evolution

  14. The Role of Fe and Ni for S-process Nucleosynthesis and Innovative Nuclear Technologies

    CERN Document Server

    Giubrone, G; Perkowski, J; Andriamonje, S; Carrapico, C; Wallner, A; Vannini, G; Quesada, J M; Lederer, C; Tarrio, D; Berthier, B; Lozano, M; Krticka, M; Domingo-Pardo, C; Chiaveri, E; Jericha, E; Ferrari, A; Massimi, C; Avrigeanu, V; Martinez, T; Guerrero, C; Andrzejewski, J; Karadimos, D; Mendoza, E; Ganesan, S; Vlachoudis, V; Milazzo, P M; Cortes, G; Becares, V; Tain, J L; Variale, V; Quinones, J; Calvino, F; Kappeler, F; Gunsing, F; Gramegna, F; Colonna, N; Marrone, S; Lebbos, E; Paradela, C; Mastinu, P F; Vaz, P; Tassan-Got, L; Kadi, Y; Dillman, I; Cano-Ott, D; Brugger, M; Audouin, L; Fernandez-Ordonez, M; Sarmento, R; Becvar, F; Goncalves, I F; Martin-Fuertes, F; Cerutti, F; Pina, G; Mosconi, M; Tagliente, G; Duran, I; Berthoumieux, E; Praena, J; Ioannides, K; Weiss, C; Mirea, M; Gomez-Hornillos, M B; Vlastou, R; Calviani, M; Nolte, R; Mengoni, A; Gonzalez-Romero, E; Marganiec, J; Leeb, H; Heil, M; Meaze, M H; Pavlik, A; Belloni, F; Harrispopulos S

    2011-01-01

    The accurate measurement of neutron capture cross sections of all Fe and Ni isotopes is important for disentangling the contribution of the s-process and the r-process to the stellar nucleosynthesis of elements in the mass range 60 < A < 120. At the same time, Fe and Ni are important components of structural materials and improved neutron cross section data is relevant in the design of new nuclear systems. With the aim of obtaining improved capture data on all stable iron and nickel isotopes, a program of measurements has been launched at the CERN Neutron Time of Flight Facility n_TOF.

  15. Neutrino mixing and big bang nucleosynthesis

    Science.gov (United States)

    Bell, Nicole

    2003-04-01

    We analyse active-active neutrino mixing in the early universe and show that transformation of neutrino-antineutrino asymmetries between flavours is unavoidable when neutrino mixing angles are large. This process is a standard Mikheyev-Smirnov-Wolfenstein flavour transformation, modified by the synchronisation of momentum states which results from neutrino-neutrino forward scattering. The new constraints placed on neutrino asymmetries eliminate the possibility of degenerate big bang nucleosynthesis.Implications of active-sterile neutrino mixing will also be reviewed.

  16. Photodisintegration of deuterium and big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Hara, K.Y.; Utsunomiya, H.; Goko, S.; Akimune, H.; Yamagata, T.; Ohta, M.; Toyokawa, H.; Kudo, K.; Uritani, A.; Shibata, Y.; Lui, Y.-W.; Ohgaki, H.

    2003-01-01

    Photodisintegration cross sections were measured for deuterium with Laser-Compton scattering γ beams at seven energies near threshold. Combined with the preceding data, R(E)=N a σv for the p(n,γ)D reaction is for the first time evaluated based on experimental data with 6% uncertainty in the energy region relevant to the big bang nucleosynthesis (BBN). The result confirms the theoretical evaluation on which the BBN in the precision era relies

  17. Bulk yields of nucleosynthesis from massive stars

    International Nuclear Information System (INIS)

    Arnett, W.D.

    1978-01-01

    Preliminary estimates are made of the absolute yields of abundant nuclei synthesized in observed stars. The compositions of nine helium stars of mass 3 or =10M/sub sun/ is estimated. A variety of choices for the initial mass function (IMF) are used to calculate the yield per stellar generation. For standard choices of the (IMF) the absolute and relative yields of 12 C, 16 O, 20 Ne, 24 Mg, the Si to Ca group, and the iron group agree with solar system values, to the accuracy of the calculations. The relative yields are surprisingly insensitive to the slope of the IMF. In a second approach, using standard estimates (Ostriker, Richstone, and Thuan) for the current rate of stellar death, I find the present rate of nucleosynthesis in the solar neighborhood to be about 10%of the average rate over galactic history. This result is consistent with many standard models of galactic evolution (for example, the Schmidt model in which star formation goes as gas density squared). It appears that if the star formation rate is high enough to produce the stars we see around us, then the nucleosynthesis rate is large enough to produce the processed nuclei (except 4 He) seen in those stars. The typical nucleosynthesis source is massive (Mapprox. =30 M/sub sun/); the death rate of such stars is a small fraction (3-10%) of recent estimates of the total rate of supernovae

  18. Proton angular distribution of {sup 16}O(d,p){sup 17}O{sup *} near a deuteron capture resonance; Evolution de la distribution angulaire des protons {sup 16}O(d,p){sup 17}O{sup *} au voisinage d'une resonance de capture du deuteron

    Energy Technology Data Exchange (ETDEWEB)

    Berthelot, R; Cohen, E; Cotton, H; Farraggi, T; Grjebine, A; Leveque, V; Naggiar, M; Roclawski-Conjeaud, D; Szteinsznaider, D [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1954-07-01

    The study of angular distributions of the protons from the reaction {sup 16}O(d,p){sup 17}O{sup *} (level at 875 keV) was made, using a photographic method, at seven different deuteron energies, from 1.66 to 2.20 MeV (obtained with the Saclay electrostatic generator). The analysis of results shows that the angular distribution for forward angles is for each chosen energy in good agreement with the stripping theory (l = 0), even at the maximum of the capture resonance of the deuteron, about 2.1 MeV. Moreover, the differential cross section at 7 deg reaches a maximum for this resonance energy. (author) [French] L'etude des distributions angulaires des protons emis au cours de la reaction {sup 16}O(d,p){sup 17}O{sup *} (niveau a 875 key) a ete effectuee, par une methode photographique, pour 7 energies differentes de deuterons comprises entre 1,66 et 2,20 MeV (obtenues grace a l'accelerateur electrostatique de Saclay). L'analyse des resultats montre que la distribution angulaire vers l'avant est, pour toutes ces energies, en bon accord avec la theorie du ''stripping'' ( 1=0), meme au maximum de la resonance de capture du deuteron situee vers 2,1 MeV. De plus, la section efficace differentielle a 7 deg passe par un maximum pour cette energie de resonance. (auteur)

  19. The r-process nucleosynthesis: Nuclear physics challenges

    Energy Technology Data Exchange (ETDEWEB)

    Goriely, S. [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles Campus de la Plaine, CP 226, 1050 Brussels (Belgium)

    2012-10-20

    About half of the nuclei heavier than iron observed in nature are produced by the socalled rapid neutron capture process, or r-process, of nucleosynthesis. The identification of the astrophysics site and the specific conditions in which the r-process takes place remains, however, one of the still-unsolved mysteries of modern astrophysics. Another underlying difficulty associated with our understanding of the r-process concerns the uncertainties in the predictions of nuclear properties for the few thousands exotic neutron-rich nuclei involved and for which essentially no experimental data exist. The present contribution emphasizes some important future challenges faced by nuclear physics in this problem, particularly in the determination of the nuclear structure properties of exotic neutron-rich nuclei as well as their radiative neutron capture rates and their fission probabilities. These quantities are particularly relevant to determine the composition of the matter resulting from the r-process. Their impact on the r-abundance distribution resulting from the decompression of neutron star matter is discussed.

  20. Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, Masahiro [Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa 277-8582 (Japan); Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa 277-8583 (Japan); Kohri, Kazunori [Theory Center, IPNS, KEK, Tsukuba 305-0801 (Japan); Sokendai, Tsukuba 305-0801 (Japan); Moroi, Takeo [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa 277-8583 (Japan); Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Takaesu, Yoshitaro, E-mail: takaesu@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan)

    2015-12-17

    We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.

  1. Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation

    Directory of Open Access Journals (Sweden)

    Masahiro Kawasaki

    2015-12-01

    Full Text Available We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.

  2. TYPE Ia SUPERNOVAE AS SITES OF THE p-PROCESS: TWO-DIMENSIONAL MODELS COUPLED TO NUCLEOSYNTHESIS

    International Nuclear Information System (INIS)

    Travaglio, C.; Gallino, R.; Roepke, F. K.; Hillebrandt, W.

    2011-01-01

    Beyond Fe, there is a class of 35 proton-rich nuclides, between 74 Se and 196 Hg, called p-nuclei. They are bypassed by the s and r neutron capture processes and are typically 10-1000 times less abundant than the s- and/or r-isotopes in the solar system. The bulk of p-isotopes is created in the 'gamma processes' by sequences of photodisintegrations and beta decays in explosive conditions in both core collapse supernovae (SNe II) and in Type Ia supernovae (SNe Ia). SNe II contribute to the production of p-nuclei through explosive neon and oxygen burning. However, the major problem in SN II ejecta is a general underproduction of the light p-nuclei for A 209 Bi. We select tracers within the typical temperature range for p-process production, (1.5-3.7) x 10 9 K, and analyze in detail their behavior, exploring the influence of different s-process distributions on the p-process nucleosynthesis. In addition, we discuss the sensitivity of p-process production to parameters of the explosion mechanism, taking into account the consequences on Fe and alpha elements. We find that SNe Ia can produce a large amount of p-nuclei, both the light p-nuclei below A = 120 and the heavy-p nuclei, at quite flat average production factors, tightly related to the s-process seed distribution. For the first time, we find a stellar source able to produce both light and heavy p-nuclei almost at the same level as 56 Fe, including the debated neutron magic 92, 94 Mo and 96, 98 Ru. We also find that there is an important contribution from the p-process nucleosynthesis to the s-only nuclei 80 Kr, 86 Sr, to the neutron magic 90 Zr, and to the neutron-rich 96 Zr. Finally, we investigate the metallicity effect on p-process production in our models. Starting with different s-process seed distributions for two metallicities Z = 0.02 and Z = 0.001, running two-dimensional SN Ia models with different initial composition, we estimate that SNe Ia can contribute to at least 50% of the solar p

  3. Testing a Dilaton Gravity Model Using Nucleosynthesis

    International Nuclear Information System (INIS)

    Boran, S.; Kahya, E. O.

    2014-01-01

    Big bang nucleosynthesis (BBN) offers one of the most strict evidences for the Λ-CDM cosmology at present, as well as the cosmic microwave background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D, 3 He, 4 He, T, and 7 Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model and Λ-CDM in the light of the astrophysical observations

  4. Supernova neutrinos, giant resonances, and nucleosynthesis

    International Nuclear Information System (INIS)

    Haxton, W.

    1990-01-01

    Almost all of the 3·10 53 ergs liberated in a core collapse supernova is radiated as neutrinos by the cooling neutron star. The neutrinos can excite nuclei in the mantle of the star by their neutral and charged current reactions. I argue that the resulting spallation reactions are an important nucleosynthesis mechanism that may be responsible for the galactic abundances of 7 Li, 11 B, 19 F, 138 La, 180 Ta, and approximately a dozen other light nuclei. 18 refs., 1 fig., 1 tab

  5. Treatment of isomers in nucleosynthesis codes

    Science.gov (United States)

    Reifarth, René; Fiebiger, Stefan; Göbel, Kathrin; Heftrich, Tanja; Kausch, Tanja; Köppchen, Christoph; Kurtulgil, Deniz; Langer, Christoph; Thomas, Benedikt; Weigand, Mario

    2018-03-01

    The decay properties of long-lived excited states (isomers) can have a significant impact on the destruction channels of isotopes under stellar conditions. In sufficiently hot environments, the population of isomers can be altered via thermal excitation or de-excitation. If the corresponding lifetimes are of the same order of magnitude as the typical time scales of the environment, the isomers have to be treated explicitly. We present a general approach to the treatment of isomers in stellar nucleosynthesis codes and discuss a few illustrative examples. The corresponding code is available online at http://exp-astro.de/isomers/.

  6. Big Bang nucleosynthesis: The standard model

    International Nuclear Information System (INIS)

    Steigman, G.

    1989-01-01

    Current observational data on the abundances of deuterium, helium-3, helium-4 and lithium-7 are reviewed and these data are used to infer (or to bound) the primordial abundances of these elements. The physics of primordial nucleosynthesis in the context of the ''standard'' (isotropic, homogeneous,...) hot big bang model is outlined and the primordial abundances predicted within the context of this model are presented. The theoretical predictions are then confronted with the observational data. This confrontation reveals the remarkable consistency of the standard model, constrains the nucleon abundance to lie within a narrow range and, permits the existence of no more than one additional flavor of light neutrinos

  7. Applications for fission product data to problems in stellar nucleosynthesis

    International Nuclear Information System (INIS)

    Mathews, G.J.

    1983-10-01

    A general overview of the nucleosynthesis mechanisms for heavy (A greater than or equal to 70) nuclei is presented with particular emphasis on critical data needs. The current state of the art in nucleosynthesis models is described and areas in which fission product data may provide useful insight are proposed. 33 references, 10 figures

  8. THE RGB AND AGB STAR NUCLEOSYNTHESIS IN LIGHT OF THE RECENT {sup 17}O(p, {alpha}){sup 14}N AND {sup 18}O(p, {alpha}){sup 15}N REACTION-RATE DETERMINATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Palmerini, S.; Sergi, M. L.; La Cognata, M.; Pizzone, R. G.; Spitaleri, C. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Lamia, L. [Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy)

    2013-02-20

    In recent years, the Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of proton-induced reactions on A = 17 and A = 18 oxygen isotopes, overcoming extrapolation procedures and enhancement effects due to electron screening. In particular, the strengths of the 20 keV and 65 keV resonances in the {sup 18}O(p, {alpha}){sup 15}N and {sup 17}O(p, {alpha}){sup 14}N reactions, respectively, have been extracted, as well as the contribution of the tail of the broad 656 keV resonance in the {sup 18}O(p, {alpha}){sup 15}N reaction inside the Gamow window. The strength of the 65 keV resonance in the {sup 17}O(p, {alpha}){sup 14}N reaction, measured by means of the THM, has been used to renormalize the corresponding resonance strength in the {sup 17}O + p radiative capture channel. As a result, more accurate reaction rates for the {sup 18}O(p, {alpha}){sup 15}N, {sup 17}O(p, {alpha}){sup 14}N, and {sup 17}O(p, {gamma}){sup 18}F processes have been deduced, devoid of systematic errors due to extrapolation or the electron screening effect. Such rates have been introduced into state-of-the-art red giant branch and asymptotic giant branch (AGB) models for proton-capture nucleosynthesis coupled with extra-mixing episodes. The predicted abundances have been compared with isotopic compositions provided by geochemical analysis of presolar grains. As a result, an improved agreement is found between the models and the isotopic mix of oxide grains of AGB origins, whose composition is the signature of low-temperature proton-capture nucleosynthesis. The low {sup 14}N/{sup 15}N found in SiC grains cannot be explained by the revised nuclear reaction rates and remains a serious problem that has not been satisfactorily addressed.

  9. Toward a self-consistent and unitary reaction network for big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Paris, Mark W.; Brown, Lowell S.; Hale, Gerald M.; Hayes-Sterbenz, Anna C.; Jungman, Gerard; Kawano, Toshihiko, E-mail: mparis@lanl.gov [Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Fuller, George M.; Grohs, Evan B. [Department of Physics, University of California, San Diego, La Jolla, CA (United States); Kunieda, Satoshi [Nuclear Data Center, Japan Atomic Energy Agency, Tokai-mura Naka-gun, Ibaraki (Japan)

    2014-07-01

    Unitarity, the mathematical expression of the conservation of probability in multichannel reactions, is an essential ingredient in the development of accurate nuclear reaction networks appropriate for nucleosynthesis in a variety of environments. We describe our ongoing program to develop a 'unitary reaction network' for the big-bang nucleosynthesis environment and look at an example of the need and power of unitary parametrizations of nuclear scattering and reaction data. Recent attention has been focused on the possible role of the {sup 9}B compound nuclear system in the resonant destruction of {sup 7}Li during primordial nucleosynthesis. We have studied reactions in the {sup 9}B compound system with a multichannel, two-body unitary R-matrix code (EDA) using the known elastic and reaction data, in a four-channel treatment. The data include elastic {sup 6}Li({sup 3}He,{sup 3}He){sup 6}Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for {sup 6}Li({sup 3}He,p){sup 8}Be* and from 0.4 to 5.0 MeV for the {sup 6}Li({sup 3}He,γ){sup 7}Be reaction. Capture data have been added to the previous analysis with integrated cross section measurements from 0.7 to 0.825 MeV for {sup 6}Li({sup 3}He,γ){sup 9}B. The resulting resonance parameters are compared with tabulated values from TUNL Nuclear Data Group analyses. Previously unidentified resonances are noted and the relevance of this analysis and a unitary reaction network for big-bang nucleosynthesis are emphasized. (author)

  10. Toward a self-consistent and unitary reaction network for big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Paris, Mark W.; Brown, Lowell S.; Hale, Gerald M.; Hayes-Sterbenz, Anna C.; Jungman, Gerard; Kawano, Toshihiko; Fuller, George M.; Grohs, Evan B.; Kunieda, Satoshi

    2014-01-01

    Unitarity, the mathematical expression of the conservation of probability in multichannel reactions, is an essential ingredient in the development of accurate nuclear reaction networks appropriate for nucleosynthesis in a variety of environments. We describe our ongoing program to develop a 'unitary reaction network' for the big-bang nucleosynthesis environment and look at an example of the need and power of unitary parametrizations of nuclear scattering and reaction data. Recent attention has been focused on the possible role of the 9 B compound nuclear system in the resonant destruction of 7 Li during primordial nucleosynthesis. We have studied reactions in the 9 B compound system with a multichannel, two-body unitary R-matrix code (EDA) using the known elastic and reaction data, in a four-channel treatment. The data include elastic 6 Li( 3 He, 3 He) 6 Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for 6 Li( 3 He,p) 8 Be* and from 0.4 to 5.0 MeV for the 6 Li( 3 He,γ) 7 Be reaction. Capture data have been added to the previous analysis with integrated cross section measurements from 0.7 to 0.825 MeV for 6 Li( 3 He,γ) 9 B. The resulting resonance parameters are compared with tabulated values from TUNL Nuclear Data Group analyses. Previously unidentified resonances are noted and the relevance of this analysis and a unitary reaction network for big-bang nucleosynthesis are emphasized. (author)

  11. Primordial nucleosynthesis revisited via Trojan Horse Results

    Directory of Open Access Journals (Sweden)

    Pizzone R.G.

    2016-01-01

    Full Text Available Big Bang Nucleosynthesis (BBN requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of d(d,pt, d(d,n3He and 3He(d,p4He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM to study reactions of relevance for the BBN and measure their astrophysical S(E-factor. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN (0.01nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances of D, 3,4He and 7Li. These were compared with the observational primordial abundance estimates in different astrophysical sites. A comparison was also performed with calculations using other reaction rates compilations available in literature.

  12. Primordial Black Holes and r-Process Nucleosynthesis.

    Science.gov (United States)

    Fuller, George M; Kusenko, Alexander; Takhistov, Volodymyr

    2017-08-11

    We show that some or all of the inventory of r-process nucleosynthesis can be produced in interactions of primordial black holes (PBHs) with neutron stars (NSs) if PBHs with masses 10^{-14}  M_{⊙}captured by a NS sinks to the center of the NS and consumes it from the inside. When this occurs in a rotating millisecond-period NS, the resulting spin-up ejects ∼0.1  M_{⊙}-0.5  M_{⊙} of relatively cold neutron-rich material. This ejection process and the accompanying decompression and decay of nuclear matter can produce electromagnetic transients, such as a kilonova-type afterglow and fast radio bursts. These transients are not accompanied by significant gravitational radiation or neutrinos, allowing such events to be differentiated from compact object mergers occurring within the distance sensitivity limits of gravitational-wave observatories. The PBH-NS destruction scenario is consistent with pulsar and NS statistics, the dark-matter content, and spatial distributions in the Galaxy and ultrafaint dwarfs, as well as with the r-process content and evolution histories in these sites. Ejected matter is heated by beta decay, which leads to emission of positrons in an amount consistent with the observed 511-keV line from the Galactic center.

  13. Chemical abundances associated with gamma-ray bursts: nucleosynthesis in afterglows

    Science.gov (United States)

    Hu, Tao; Wang, Min

    2014-03-01

    Gamma-ray burst (GRB) ejecta carries huge amounts of energy expanding into the surrounding medium and heats up these materials, making it possible that nucleosynthesis can take place in such hot sites in afterglow stage. Here, we study possible changes in chemical abundances in the GRB afterglow processes of Wolf-Rayet (WR) star wind environments (Case A) and constant density surroundings (Case B). We find that the light element of lithium-beryllium-boron could occur in the afterglows via He+He process and spallation reactions. Some isotopes of F, Ne, Mg, Al, Si, P, S and Fe-group elements are also new species formed in the afterglows via proton-, neutron- and α-capture. The results show that the nucleosynthetic yields might be a diagnostic of the GRB's ambient environment. Our calculations indicate that Mg, Al, Si, P, Cr, Mn, Fe and Co have trended to appear in Case A, while Ne, Ti and Ni trend to occur in Case B. Furthermore, although some species have occurred both in Cases A and B, their mass fractions are quite different in these two cases. Here, we show that the mass fractions of 7Li, 7Be, 24Mg and 30Si are higher in Case A than that in Case B, but 18F gives an opposite conclusion. Nucleosynthetic outputs might also be an indice to estimate the luminosity-temperature relation factor β. In this study, when β reduces, the mass abundances of 11B and 20Ne are higher in Case B than that in Case A; in contrast, as the β becomes larger, this trend would be reversed; therefore, perhaps we could select the above elements as the indicators to estimate the properties of the surroundings around the GRBs. We also suggest that the spectroscopic observations of a GRB afterglow could only reveal the nucleosynthetic outputs from the interaction site between the GRB jet and its ambient matter, but could not represent the original composition of the pre-GRB surrounding medium.

  14. Fission and r-process nucleosynthesis in neutron star mergers

    International Nuclear Information System (INIS)

    Giuliani, Samuel Andrea

    2018-01-01

    Fission plays a crucial role for the r-process nucleosynthesis in neutron star mergers. Due to the high neutron densities achieved in this astrophysical scenario the sequence of neutron captures and beta decays that constitutes the r process produces superheavy neutron rich nuclei that become unstable against fission. Fission determines thus the heaviest nuclei that can be produced by the r process and the fission yields shape the abundances of lighter nuclei. But despite the key role of fission the sensitivity of the r-process nucleosynthesis to uncertainties in fission predictions has not been explored. Nowadays there are only few set of fission rates suited for r-process calculations and most of them rely on a simplified treatment of the fission process. In this thesis we go beyond these approximations and compute the fission properties of r-process nuclei using the energy density functional approach. Fission is described as a tunneling process where the nucleus ''moves'' in a collective space characterized by coordinates describing the nuclear shape. Thus fission depends on the evolution of the energy with the deformation but also on the inertia due to the motion in the collective space. This is analogous to the quantum mechanical tunneling of a particle inside a potential well. In our study the relevant quantities for the description of the fission process are consistently computed for 3642 nuclei following the Hartree-Fock-Bogolyubov theory with constraining operators. We perform an extensive benchmark against the available experimental data and explore the variations of the fission properties along the superheavy landscape. We find that while collective inertias have a strong impact in the fission probabilities of light nuclei their role becomes less relevant in r -process nuclei. Within the statistical model we compute the neutron induced stellar reaction rates relevant for the r-process nucleosynthesis. These sets of stellar reaction

  15. Neutrino nucleosynthesis in supernovae: Shell model predictions

    International Nuclear Information System (INIS)

    Haxton, W.C.

    1989-01-01

    Almost all of the 3 · 10 53 ergs liberated in a core collapse supernova is radiated as neutrinos by the cooling neutron star. I will argue that these neutrinos interact with nuclei in the ejected shells of the supernovae to produce new elements. It appears that this nucleosynthesis mechanism is responsible for the galactic abundances of 7 Li, 11 B, 19 F, 138 La, and 180 Ta, and contributes significantly to the abundances of about 15 other light nuclei. I discuss shell model predictions for the charged and neutral current allowed and first-forbidden responses of the parent nuclei, as well as the spallation processes that produce the new elements. 18 refs., 1 fig., 1 tab

  16. Isotope ratio in stellar atmospheres and nucleosynthesis

    International Nuclear Information System (INIS)

    Barbuy, B.L.S.

    1987-01-01

    The determination of isotopic ratios in stellar atmospheres is studied. The isotopic shift of atomic and molecular lines of different species of a certain element is examined. CH and MgH lines are observed in order to obtain the 12 C: 13 C and 24 Mg: 25 Mg: 26 Mg isotpic ratios. The formation of lines in stellar atmospheres is computed and the resulting synthetic spectra are employed to determine the isotopic abundances. The results obtained for the isotopic ratios are compared to predictions of nucleosynthesis theories. Finally, the concept of primary and secondary element is discussed, and these definitions are applied to the observed variations in the abundance of elements as a function of metallicity. (author) [pt

  17. Big-Bang nucleosynthesis and lithium abundance

    International Nuclear Information System (INIS)

    Singh, Vinay; Lahiri, Joydev; Bhowmick, Debasis; Basu, D.N.

    2017-01-01

    The predictions of the standard big-bang nucleosynthesis (BBN) theory depend on the astrophysical nuclear reaction rates and on additional three parameters, the number of flavours of light neutrinos, the neutron lifetime and the baryon-to-photon ratio in the uni- verse. The effect of the modification of thirty-five reaction rates on light element abundance yields in BBN was investigated earlier by us. In the present work we have replaced the neutron lifetime, baryon-to-photon ratio by the most recent values and further modified 3 He( 4 He,γ) 7 Be reaction rate which is used directly for estimating the formation of 7 Li as a result of β + decay by the most recent equation. We find that these modifications reduce the calculated abundance of 7 Li by ∼ 12%

  18. Primordial nucleosynthesis in the new cosmology

    International Nuclear Information System (INIS)

    Cyburt, R.H.

    2003-01-01

    Big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies independently predict the universal baryon density. Comparing their predictions will provide a fundamental test on cosmology. Using BBN and the CMB together, we will be able to constrain particle physics, and predict the primordial, light element abundances. These future analyses hinge on new experimental and observational data. New experimental data on nuclear cross sections will help reduce theoretical uncertainties in BBN's predictions. New observations of light element abundances will further sharpen BBN's probe of the baryon density. Observations from the MAP and PLANCK satellites will measure the fluctuations in the CMB to unprecedented accuracy, allowing the precise determination of the baryon density. When combined, this data will present us with the opportunity to perform precision cosmology

  19. Constraints on vacuum energy from structure formation and Nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Fred C.; Grohs, Evan [Physics Department, University of Michigan, 450 Church Street, Ann Arbor, MI, 48109 (United States); Alexander, Stephon [Physics Department, Brown University, 6127 Wilder Laboratory, Providence, RI, 02912 (United States); Mersini-Houghton, Laura, E-mail: fca@umich.edu, E-mail: stephon_alexander@brown.edu, E-mail: egrohs@umich.edu, E-mail: mersini@physics.unc.edu [Physics Department, University of North Carolina, 120 E. Cameron Avenue, Chapel Hill, NC, 27599 (United States)

    2017-03-01

    This paper derives an upper limit on the density ρ{sub Λ} of dark energy based on the requirement that cosmological structure forms before being frozen out by the eventual acceleration of the universe. By allowing for variations in both the cosmological parameters and the strength of gravity, the resulting constraint is a generalization of previous limits. The specific parameters under consideration include the amplitude Q of the primordial density fluctuations, the Planck mass M {sub pl}, the baryon-to-photon ratio η, and the density ratio Ω {sub M} /Ω {sub b} . In addition to structure formation, we use considerations from stellar structure and Big Bang Nucleosynthesis (BBN) to constrain these quantities. The resulting upper limit on the dimensionless density of dark energy becomes ρ{sub Λ}/ M {sub pl}{sup 4} < 10{sup −90}, which is ∼30 orders of magnitude larger than the value in our universe ρ{sub Λ}/ M {sub pl}4 ∼ 10{sup −120}. This new limit is much less restrictive than previous constraints because additional parameters are allowed to vary. With these generalizations, a much wider range of universes can develop cosmic structure and support observers. To constrain the constituent parameters, new BBN calculations are carried out in the regime where η and G = M {sub pl}{sup −2} are much larger than in our universe. If the BBN epoch were to process all of the protons into heavier elements, no hydrogen would be left behind to make water, and the universe would not be viable. However, our results show that some hydrogen is always left over, even under conditions of extremely large η and G , so that a wide range of alternate universes are potentially habitable.

  20. Explosive nucleosynthesis in zones rich in hydrogen and helium

    International Nuclear Information System (INIS)

    Toussaint, Jacques.

    1975-01-01

    Explosive nucleosynthesis was studied for element with masses lower than that of 35 Cl at temperatures between 10 8 to 10 9 K. It is shown that in some astrophysical objects (Novae, Supernovae or super-massive-stars) an explosive nucleosynthesis of isotopes such as 3 He, 7 Li, 25 Mg or 29 Si is possible. The existence of those elements in the interstellar medium would make possible, ultimately, the formation of heavier elements (iron peak and above) [fr

  1. (n,γ) (γ,n) unstability in the r process of nucleosynthesis

    International Nuclear Information System (INIS)

    Duarte, S.J.B.

    1977-01-01

    The equilibrium approximation for capture and neutron photoemission reactions within r process of nucleosynthesis is analysed. This analysis is considered for whole range of neutron density and temperature which enable the ocurrence of the process. In this way it is necessary to know capture and photo-emission rates for approximately 2000 nuclei. The detailed balance is used in rate relation of above-mencioned reactions, and its application, under temperature, and its application, under temperature conditions and neutron density is discussed. The others nuclear parameters used in face of the nuclei involved in r process are far away of the β stability line. The temperature conditions and neutron density are presented from the point where the equilirbium approximation is not applicable. The procedure to be used in the application of the obtained results in dynamical models of r process is also presented. (M.C.K.) [pt

  2. Big-bang nucleosynthesis - observational aspects

    International Nuclear Information System (INIS)

    Pagel, B.E.J.

    1990-01-01

    Extrapolation of observational data on the abundances of D, 3 He, 4 He and 7 Li in various astrophysical objects to derive their primordial values leads to results in good accordance with calculations from Standard Big Bang nucleosynthesis theory over 9 orders of magnitude in abundance and has led to the following predictions: There are not more than 3 light neutrino species or other particles contributing relativistic degrees of freedom at temperatures of a few MeV; the neutron half-life is less than 10.4 minutes; and baryonic dark matter exists, but not in sufficient quantities to close the universe. (The first two of these predictions have been confirmed by laboratory experiments). Searches for a primordial component in the abundance of any other element heavier than hydrogen - such as might have resulted from inhomogeneities due to phase transitions in the early universe, notably the quark-hadron transition - have so far proved completely negative. The primordial helium abundance is found from observations of extragalactic ionized hydrogen clouds to be close to 0.230 by mass, a little lower than predicted, but the difference does not exceed likely errors. (orig.)

  3. Summary of Recent Developments in Primordial Nucleosynthesis.

    Science.gov (United States)

    Schramm, D N

    1993-06-01

    This paper summarizes the recent observational and theoretical results on Big Bang Nucleosynthesis. In particular, it is shown that the new Pop II (6)Li results strongly support the argument that the Spite Plateau lithium is a good estimate of the primordial value. The (6)Li is consistent with the Be and Be found in Pop II stars, assuming those elements are cosmic ray produced. The HST (2)D value tightens the (2)D arguments and the observation of the (3)He in planetary nebula strengthens the (3)He +(2)D argument as a lower bound on Ωb. The new low metalicity (4)He determinations slightly raise the best primordial (4)He number and thus make a better fit and avoid a potential problem. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ωb are possible vis-à-vis the homogeneous model; hence, the robustness of Ωb∼ 0.05 is now apparent. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ωb∼ 1 seems to be definitely excluded, so, if Ω= 1, as some recent observations may hint, then non-baryonic dark matter is required.

  4. Inhomogeneous neutrino degeneracy and big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Whitmire, Scott E.; Scherrer, Robert J.

    2000-01-01

    We examine big bang nucleosynthesis (BBN) in the case of inhomogeneous neutrino degeneracy, in the limit where the fluctuations are sufficiently small on large length scales that the present-day element abundances are homogeneous. We consider two representative cases: degeneracy of the electron neutrino alone and equal chemical potentials for all three neutrinos. We use a linear programming method to constrain an arbitrary distribution of the chemical potentials. For the current set of (highly restrictive) limits on the primordial element abundances, homogeneous neutrino degeneracy barely changes the allowed range of the baryon-to-photon ratio η. Inhomogeneous degeneracy allows for little change in the lower bound on η, but the upper bound in this case can be as large as η=1.1x10 -8 (only ν e degeneracy) or η=1.0x10 -9 (equal degeneracies for all three neutrinos). For the case of inhomogeneous neutrino degeneracy, we show that there is no BBN upper bound on the neutrino energy density, which is bounded in this case only by limits from structure formation and the cosmic microwave background. (c) 2000 The American Physical Society

  5. What's Next for Big Bang Nucleosynthesis?

    International Nuclear Information System (INIS)

    Cyburt, R.H.

    2005-01-01

    Big bang nucleosynthesis (BBN) plays an important role in the standard hot big bang cosmology. BBN theory is used to predict the primordial abundances of the lightest elements, hydrogen, helium and lithium. Comparison between the predicted and observationally determined light element abundances provides a general test of concordance and can be used to fix the baryon content in the universe. Measurements of the cosmic microwave background (CMB) anisotropies now supplant BBN as the premier baryometer, especially with the latest results from the WMAP satellite. With the WMAP baryon density, the test of concordance can be made even more precise. Any disagreement between theory predictions and observations requires careful discussion. Several possibilities exist to explain discrepancies; (1) observational systematics (either physical or technical) may not be properly treated in determining primordial light element abundances (2) nuclear inputs that determine the BBN predictions may have unknown systematics or may be incomplete, and (3) physics beyond that included in the standard BBN scenario may need to be included in the theory calculation. Before we can be absolutely sure new physics is warranted, points (1) and (2) must be addressed and ruled out. All of these scenarios rely on experimental or observational data to make definitive statements of their applicability and range of validity, which currently is not at the level necessary to discern between these possibilities with high confidence. Thus, new light element abundance observations and nuclear experiments are needed to probe these further. Assuming concordance is established, one can use the light element observations to explore the evolution from their primordial values. This can provide useful information on stellar evolution, cosmic rays and other nuclear astrophysics. When combined with detailed models, BBN, the CMB anisotropy and nuclear astrophysics can provide us with information about the populations

  6. Neutrino-Induced Nucleosynthesis in Helium Shells of Early Core-Collapse Supernovae

    Directory of Open Access Journals (Sweden)

    Banerjee Projjwal

    2016-01-01

    Full Text Available We summarize our studies on neutrino-driven nucleosynthesis in He shells of early core-collapse supernovae with metallicities of Z ≲ 10−3 Z⊙. We find that for progenitors of ∼ 11–15 M⊙, the neutrons released by 4He(ν¯ee, e+n3H in He shells can be captured to produce nuclei with mass numbers up to A ∼ 200. This mechanism is sensitive to neutrino emission spectra and flavor oscillations. In addition, we find two new primary mechanisms for neutrino-induced production of 9Be in He shells. The first mechanism produces 9Be via 7Li(n,γ8Li(n,γ9Li(e− ν¯ee9Be and relies on a low explosion energy for its survival. The second mechanism operates in progenitors of ∼ 8 M⊙, where 9Be can be produced directly via 7Li(3H, n09Be during the rapid expansion of the shocked Heshell material. The light nuclei 7Li and 3H involved in these mechanisms are produced by neutrino interactions with 4He. We discuss the implications of neutrino-induced nucleosynthesis in He shells for interpreting the elemental abundances in metal-poor stars.

  7. Big bang nucleosynthesis revisited via Trojan Horse method measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pizzone, R. G.; Spartá, R.; Spitaleri, C.; La Cognata, M.; Tumino, A. [INFN—Laboratori Nazionali del Sud, Via Santa Sofia 62, I-95123 Catania (Italy); Bertulani, C. A.; Lalmansingh, J. [Department of Physics and Astronomy, Texas A and M University, Commerce, TX 75025 (United States); Lamia, L. [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via Santa Sofia 64, I-95123 Catania (Italy); Mukhamedzhanov, A., E-mail: rgpizzone@lns.infn.it [Cyclotron Institute, Texas A and M University, College Station, TX 77843 (United States)

    2014-05-10

    Nuclear reaction rates are among the most important input for understanding primordial nucleosynthesis and, therefore, for a quantitative description of the early universe. An up-to-date compilation of direct cross-sections of {sup 2}H(d, p){sup 3}H, {sup 2}H(d, n){sup 3}He, {sup 7}Li(p, α){sup 4}He, and {sup 3}He(d, p){sup 4}He reactions is given. These are among the most uncertain cross-sections used and input for big bang nucleosynthesis calculations. Their measurements through the Trojan Horse method are also reviewed and compared with direct data. The reaction rates and the corresponding recommended errors in this work were used as input for primordial nucleosynthesis calculations to evaluate their impact on the {sup 2}H, {sup 3,4}He, and {sup 7}Li primordial abundances, which are then compared with observations.

  8. Big-Bang nucleosynthesis with updated nuclear data

    Energy Technology Data Exchange (ETDEWEB)

    Coc, Alain [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), CNRS/IN2P3, Universite Paris Sud 11, UMR 8609, Batiment 104, F-91405 Orsay Campus (France); Vangioni, Elisabeth, E-mail: Alain.Coc@csnsm.in2p3.f, E-mail: vangioni@iap.f [Institut d' Astrophysique de Paris, UMR-7095 du CNRS, Universite Pierre et Marie Curie, 98 bis bd Arago, 75014 Paris (France)

    2010-01-01

    Primordial nucleosynthesis is one of the three evidences for the Big-Bang model together with the expansion of the Universe and the Cosmic Microwave Background. There is a good global agreement over a range of nine orders of magnitude between abundances of {sup 4}He, D, {sup 3}He and {sup 7}Li deduced from observations and calculated primordial nucleosynthesis. This comparison was used to determine the baryonic density of the Universe. For this purpose, it is now superseded by the analysis of the Cosmic Microwave Background (CMB) radiation anisotropies. Big-Bang nucleosynthesis remains, nevertheless, a valuable tool to probe the physics of the early Universe. However, the yet unexplained, discrepancy between the calculated and observed lithium primordial abundances, has not been reduced, neither by recent nuclear physics experiments, nor by new observations.

  9. Introduction to big bang nucleosynthesis and modern cosmology

    Science.gov (United States)

    Mathews, Grant J.; Kusakabe, Motohiko; Kajino, Toshitaka

    Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the testing ground upon which many cosmological models must ultimately rest. It is our only probe of the universe during the important radiation-dominated epoch in the first few minutes of cosmic expansion. This paper reviews the basic equations of space-time, cosmology, and big bang nucleosynthesis. We also summarize the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measurements are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we analyze the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field.

  10. Nucleosynthesis confronts an unstable inert 17 keV state

    International Nuclear Information System (INIS)

    Enqvist, K.; Kainulainen, K.; Thomson, M.

    1991-01-01

    We study the cosmological consequences of an inert 17 keV state mixing with the electron neutrino. We find that the nucleosynthesis upper bound on the primordial helium abundance prohibits the existence of such a state, unless its lifetime falls into the range 6x10 -4 s vac -2 s. In this range the decay occurs after the chemical decoupling of the electron neutrinos and before the beginning of the nucleosynthesis, with the result that the predicted helium abundance can be lower than what it would be in the standard scenario. (orig.)

  11. Nonuniversal scalar-tensor theories and big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth

    2009-01-01

    We investigate the constraints that can be set from big bang nucleosynthesis on two classes of models: extended quintessence and scalar-tensor theories of gravity in which the equivalence principle between standard matter and dark matter is violated. In the latter case, and for a massless dilaton with quadratic couplings, the phase space of theories is investigated. We delineate those theories where attraction toward general relativity occurs. It is shown that big bang nucleosynthesis sets more stringent constraints than those obtained from Solar System tests.

  12. The quark-hadron phase transition and primordial nucleosynthesis

    Science.gov (United States)

    Hogan, Craig J.

    1987-01-01

    After presenting the current view of the processes taking place during the cosmological transition from 'quark soup' to normal hadron matter, attention is given to what happens to cosmological nucleosynthesis in the presence of small-scale baryon inhomogeneities. The QCD phase transition is among the plausible sources of this inhomogeneity. It is concluded that the formation of primordial 'quark nuggets' and other cold exotica requires very low entropy regions at the outset, and that even the more modest nonlinearities perturbing nucleosynthesis probably require some ingredient in addition to a quiescent, mildly supercooled transition.

  13. Nonuniversal scalar-tensor theories and big bang nucleosynthesis

    Science.gov (United States)

    Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth

    2009-05-01

    We investigate the constraints that can be set from big bang nucleosynthesis on two classes of models: extended quintessence and scalar-tensor theories of gravity in which the equivalence principle between standard matter and dark matter is violated. In the latter case, and for a massless dilaton with quadratic couplings, the phase space of theories is investigated. We delineate those theories where attraction toward general relativity occurs. It is shown that big bang nucleosynthesis sets more stringent constraints than those obtained from Solar System tests.

  14. Experimental Neutron Capture Rate Constraint Far from Stability.

    Science.gov (United States)

    Liddick, S N; Spyrou, A; Crider, B P; Naqvi, F; Larsen, A C; Guttormsen, M; Mumpower, M; Surman, R; Perdikakis, G; Bleuel, D L; Couture, A; Crespo Campo, L; Dombos, A C; Lewis, R; Mosby, S; Nikas, S; Prokop, C J; Renstrom, T; Rubio, B; Siem, S; Quinn, S J

    2016-06-17

    Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on ^{69}Ni, a nucleus that is five neutrons away from the last stable isotope of Ni. The implications of this measurement on nucleosynthesis around mass 70 are discussed, and the impact of similar future measurements on the understanding of the origin of the heavy elements in the cosmos is presented.

  15. Current quests in nucleosynthesis: present and future neutron-induced reaction measurements

    Directory of Open Access Journals (Sweden)

    Praena J.

    2014-03-01

    Full Text Available We present some open questions in nucleosynthesis focused on the measurement of relevant neutron capture cross-sections and on new experimental methods. We review the recent 63Ni(n,γ experiment carried out at the n_TOF facility at CERN and its astrophysical implications as well as future experiments and opportunities at n_TOF. We argue some improvements in the measurement of cross-sections by activation arising from a new method for the generation of stellar neutron spectra. We show preliminary results of the experimental validation of the method. We discuss the astrophysical implications of the 181Ta(n,γ stellar cross-section measured with this method. Finally, we describe challenging experiments consisting of in situ radioactive ion beams and stellar neutron beams.

  16. Early nucleosynthesis, particle physics and the quark-lithium connection

    International Nuclear Information System (INIS)

    Reeves, H.; Audouze, J.; Delbourgo-Salvador, P.; Salati, P.; California Univ., Berkeley

    1987-01-01

    Three questions relevant to the primordial nucleosynthesis of the very light elements are discussed in this contribution: 1. It is argued that the ''standard'' Big Bang nucleosynthesis models are strenghtened if D is destroyed thoroughly during the galactic history. This can be achieved by specific models of chemical evolution of galaxies like those assuming a rate of star formation varying with time. 2. The existence of non baryonic particles such as massive neutrinos or supersymetric particles (gravitinos, photinos ...) might affect this early nucleosynthesis. If they are massive (≥ 500 MeV) and long lived enough (≥ 10 5 sec) the energetic photons released by their possible decay might affect the relative abundances of the light elements. In the case of the photinos, which are the supersymetric particles and which might be experimentally detectable in a near future, this possible effect can be used as to constrain the predictions on their physical properties (mass, lifetime...). 3. The early nucleosynthesis can be affected by the inhomogeneities triggered by the quark-hadron phase transition. It is argued that the primordial abundance of 7 Li limits very severely this possibility. As in the case of photinos the relation between the early synthesis of 7 Li and the characteristics of this quark-hadron phase transition may provide interesting constraints on some important physical parameters such as the constant B of the quark-bag model

  17. Collaborative Research: Neutrinos and Nucleosynthesis in Hot Dense Matter

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, Gail [North Carolina State Univ., Raleigh, NC (United States); Schaefer, Thomas [North Carolina State Univ., Raleigh, NC (United States)

    2015-05-31

    The major accomplishments of the research activity at NC State during the five years were: to determine the effects and signatures of turbulence in supernova, to calculate r-process and supernova nucleosynthesis, and to determine the neutrino scattering and flavor transformation that occurs in black hole accretion disks. This report goes into more detail on them.

  18. Capturing Thoughts, Capturing Minds?

    DEFF Research Database (Denmark)

    Nielsen, Janni

    2004-01-01

    Think Aloud is cost effective, promises access to the user's mind and is the applied usability technique. But 'keep talking' is difficult, besides, the multimodal interface is visual not verbal. Eye-tracking seems to get around the verbalisation problem. It captures the visual focus of attention...

  19. Primordial nucleosynthesis as a probe of particle physics and cosmology

    International Nuclear Information System (INIS)

    Walker, T.P.

    1987-01-01

    In this dissertation, the author uses the success of the standard model of big-bang nucleosynthesis to examine the effects of interacting particle species and the effect of varying coupling constants, predicted by theories set in extra dimensions, on primordial nucleosynthesis. A review is given of the standard model and of the abundances of the light elements expected to be produced in the early Universe. The weakest piece of the concordance between the standard model of big-bang nucleosynthesis and observation is the production and primordial abundance of 7 Li. Therefore he discusses the production of 7 Li in astrophysical environments other than the early Universe and shows that the predictions of big-bang nucleosynthesis, when supplemented by those due to astrophysical sources, are in good agreement with observation. He then shows that the effect on big-bang nucleosynthesis of an additional particle species which remains coupled to either photons or light neutrinos can be quite different from that predicted by the equivalent number of neutrino species parameterization, which does work for decoupled additional species. In particular he considers the case of an additional axion-like particle and shows that its effect is to decrease the amount of 4 He produced in the big-bang. In addition, he considers the effects of varying coupling constants on 4 He production in the big-bang and shows that constraining Y p = 0.24 ± 0.01 leads to a constraint on the time variation of the fine-structure constant of |dln α/dt| ≤ x 10 -14

  20. Capture cross sections on unstable nuclei

    Science.gov (United States)

    Tonchev, A. P.; Escher, J. E.; Scielzo, N.; Bedrossian, P.; Ilieva, R. S.; Humby, P.; Cooper, N.; Goddard, P. M.; Werner, V.; Tornow, W.; Rusev, G.; Kelley, J. H.; Pietralla, N.; Scheck, M.; Savran, D.; Löher, B.; Yates, S. W.; Crider, B. P.; Peters, E. E.; Tsoneva, N.; Goriely, S.

    2017-09-01

    Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.

  1. Capture cross sections on unstable nuclei

    Directory of Open Access Journals (Sweden)

    Tonchev A.P.

    2017-01-01

    Full Text Available Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.

  2. Asymptotic normalization coefficients from proton transfer reactions and astrophysical S factors for the CNO 13C(p,gamma)14N radiative capture prosess

    Czech Academy of Sciences Publication Activity Database

    Mukhamedzhanov, A. M.; Azhari, A.; Burjan, Václav; Gagliardi, C. A.; Kroha, Václav; Sattarov, A.; Tang, X.; Trache, L.; Tribble, R. E.

    2003-01-01

    Roč. 725, č. 725 (2003), s. 279-294 ISSN 0375-9474 R&D Projects: GA ČR GA202/01/0709; GA MŠk ME 385 Institutional research plan: CEZ:AV0Z1048901 Keywords : radiative capture reaction * asymptotic normalization coefficient Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.761, year: 2003

  3. Asymptotic normalization coefficients from proton transfer reactions and astrophysical S factors for the (CNOC)-C-13(p, gamma)N-14 radiative capture process

    Czech Academy of Sciences Publication Activity Database

    Mukhamedzhanov, A. M.; Azhari, A.; Burjan, Václav; Gagliardi, C. A.; Kroha, Václav; Sattarov, A.; Tang, X.; Trache, L.; Tribble, R. E.

    2003-01-01

    Roč. 725, č. 22 (2003), s. 279-294 ISSN 0375-9474 R&D Projects: GA ČR GA202/01/0709; GA MŠk ME 385 Institutional research plan: CEZ:AV0Z1048901 Keywords : radiative capture reaction * asymptotic normalization coefficient Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.761, year: 2003

  4. Proton-proton bremsstrahlung

    International Nuclear Information System (INIS)

    Fearing, H.W.

    1990-01-01

    We summarize some of the information about the nucleon-nucleon force which has been obtained by comparing recent calculations of proton-proton bremsstrahlung with cross section and analyzing power data from the new TRIUMF bremsstrahlung experiment. Some comments are made as to how these results can be extended to neutron-proton bremsstrahlung. (Author) 17 refs., 6 figs

  5. High-entropy ejections from magnetized proto-neutron star winds: implications for heavy element nucleosynthesis

    Science.gov (United States)

    Thompson, Todd A.; ud-Doula, Asif

    2018-06-01

    Although initially thought to be promising for production of the r-process nuclei, standard models of neutrino-heated winds from proto-neutron stars (PNSs) do not reach the requisite neutron-to-seed ratio for production of the lanthanides and actinides. However, the abundance distribution created by the r-, rp-, or νp-processes in PNS winds depends sensitively on the entropy and dynamical expansion time-scale of the flow, which may be strongly affected by high magnetic fields. Here, we present results from magnetohydrodynamic simulations of non-rotating neutrino-heated PNS winds with strong dipole magnetic fields from 1014 to 1016 G, and assess their role in altering the conditions for nucleosynthesis. The strong field forms a closed zone and helmet streamer configuration at the equator, with episodic dynamical mass ejections in toroidal plasmoids. We find dramatically enhanced entropy in these regions and conditions favourable for third-peak r-process nucleosynthesis if the wind is neutron-rich. If instead the wind is proton-rich, the conditions will affect the abundances from the νp-process. We quantify the distribution of ejected matter in entropy and dynamical expansion time-scale, and the critical magnetic field strength required to affect the entropy. For B ≳1015 G, we find that ≳10-6 M⊙ and up to ˜10-5 M⊙ of high-entropy material is ejected per highly magnetized neutron star birth in the wind phase, providing a mechanism for prompt heavy element enrichment of the universe. Former binary companions identified within (magnetar-hosting) supernova remnants, the remnants themselves, and runaway stars may exhibit overabundances. We provide a comparison with a semi-analytic model of plasmoid eruption and discuss implications and extensions.

  6. Controlled Nucleosynthesis Breakthroughs in Experiment and Theory

    CERN Document Server

    Adamenko, Stanislav; Merwe, Alwyn

    2007-01-01

    This book ushers in a new era of experimental and theoretical investigations into collective processes, structure formation, and self-organization of nuclear matter. It reports the results of experiments wherein for the first time the nuclei constituting our world (those displayed in Mendeleev's table as well as the super-heavy ones) have been artificially created. Pioneering breakthroughs are described, achieved at the "Proton-21" Laboratory, Kiev, Ukraine, in a variety of new physical and technological directions. A detailed description of the main experiments, their analyses, and the interpretation of copious experimental data are given, along with the methodology governing key measurements and the processing algorithms of the data that empirically confirm the occurrence of macroscopic self-organizing processes leading to the nuclear transformations of various materials. The basic concepts underlying the initiation of self-sustaining collective processes that result in the formation of nuclear structures a...

  7. Impact of (α, n) reactions on the nucleosynthesis in neutrino-driven winds

    Energy Technology Data Exchange (ETDEWEB)

    Bliss, Julia [Institut fuer Kernphysik, TU Darmstadt (Germany); Arcones, Almudena [Institut fuer Kernphysik, TU Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH (Germany); Montes, Fernando; Pereira, Jorge [National Superconducting Cyclotron Laboratory, Michigan State University (United States); Joint Institute for Nuclear Astrophysics (United States)

    2015-07-01

    Neutrino-driven winds that follow core-collapse supernova explosions are an exciting astrophysical site for the synthesis of heavy elements. Although recent hydrodynamical simulations show that the conditions in the wind are not extreme enough for a r-process up to uranium, neutrino-driven winds may be the astrophysical site where lighter heavy elements between Sr and Ag are produced. However, it is still not clear if the conditions in the wind are slightly neutron-rich, proton-rich or turn proton-rich for some time. In neutron-rich winds, (α,n) reactions are key to move matter beyond the Fe-group towards heavier elements. Due to the deficit of experimental information, the relevant reaction rates have mostly been calculated with codes based on Hauser-Feshbach models. Although these codes have been cross-checked with experimental data in regions close to stability, their accuracy is questionable as one moves towards more exotic regions. We present the impact of (α,n) reactions on the nucleosynthesis of elements between Sr and Ag in neutrino-driven winds.

  8. Proton capture in the nuclei 21Ne and 22Ne and its influence on the solar hydrogen burning in the neon-sodium cyclus

    International Nuclear Information System (INIS)

    Goerres, J.

    1983-01-01

    The aim of this thesis was to remove the uncertainties in the reaction rates of 21 Ne(p,γ) 22 Na and 22 Ne(p,γ) 23 Na in order to can make founded statements about the hydrogen burning in the NeNa cyclus. After the description of the experimental arrangement the search for resonances in the reaction 21 Ne(p,γ) 22 Na below Esub(p)=355 keV is reported. While the theory of the direct radiation capture is discussed the experimental results of the search for this transitions in 21 Ne(p,γ) 22 Na respectively 22 Ne(p,γ) 23 Na are presented. The astrophysical aspects of the results of this thesis are discussed and summarizingly presented. (orig./HSI) [de

  9. Primordial and Stellar Nucleosynthesis Chemical Evolution of Galaxies

    International Nuclear Information System (INIS)

    Chiosi, Cesare

    2010-01-01

    Following a brief introduction to early Universe cosmology, we present in some detail the results of primordial nucleosynthesis. Then we summarize the basic theory of nuclear reactions in stars and sketch the general rules of stellar evolution. We shortly review the subject of supernova explosions both by core collapse in massive stars (Type II) and carbon-deflagration in binary systems when one of the components is a White Dwarf accreting mass from the companion (Type Ia). We conclude the part dedicated to nucleosynthesis with elementary notions on the s- and r-process. Finally, we shortly address the topic of galactic chemical evolution and highlight some simple solutions aimed at understanding the main observational data on abundances and abundance ratios.

  10. The standard and degenerate primordial nucleosynthesis versus recent experimental data

    International Nuclear Information System (INIS)

    Esposito, S.; Mangano, G.; Miele, G.; Pisanti, O.

    2000-01-01

    We report the results on Big Bang Nucleosynthesis (BBN) based on an updated code, with accuracy of the order of 0.1% on He4 abundance, compared with the predictions of other recent similar analysis. We discuss the compatibility of the theoretical results, for vanishing neutrino chemical potentials, with the observational data. Bounds on the number of relativistic neutrinos and baryon abundance are obtained by a likelihood analysis. We also analyze the effect of large neutrino chemical potentials on primordial nucleosynthesis, motivated by the recent results on the Cosmic Microwave Background Radiation spectrum. The BBN exclusion plots for electron neutrino chemical potential and the effective number of relativistic neutrinos are reported. We find that the standard BBN seems to be only marginally in agreement with the recent BOOMERANG and MAXIMA-1 results, while the agreement is much better for degenerate BBN scenarios for large effective number of neutrinos, N ν ∼ 10. (author)

  11. Particle Physics Catalysis of Thermal Big Bang Nucleosynthesis

    International Nuclear Information System (INIS)

    Pospelov, Maxim

    2007-01-01

    We point out that the existence of metastable, τ>10 3 s, negatively charged electroweak-scale particles (X - ) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X - with helium, formed at temperatures of about T=10 8 K, lead to the catalytic enhancement of 6 Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X - does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X - particles (τ>10 5 s) relative to entropy of n X - /s -17 , which is one of the most stringent probes of electroweak scale remnants known to date

  12. Particle physics catalysis of thermal big bang nucleosynthesis.

    Science.gov (United States)

    Pospelov, Maxim

    2007-06-08

    We point out that the existence of metastable, tau>10(3) s, negatively charged electroweak-scale particles (X-) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X- with helium, formed at temperatures of about T=10(8) K, lead to the catalytic enhancement of 6Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X- does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X- particles (tau>10(5) s) relative to entropy of nX-/s less, approximately <3x10(-17), which is one of the most stringent probes of electroweak scale remnants known to date.

  13. Dirac fields in loop quantum gravity and big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Bojowald, Martin; Das, Rupam; Scherrer, Robert J.

    2008-01-01

    Big bang nucleosynthesis requires a fine balance between equations of state for photons and relativistic fermions. Several corrections to equation of state parameters arise from classical and quantum physics, which are derived here from a canonical perspective. In particular, loop quantum gravity allows one to compute quantum gravity corrections for Maxwell and Dirac fields. Although the classical actions are very different, quantum corrections to the equation of state are remarkably similar. To lowest order, these corrections take the form of an overall expansion-dependent multiplicative factor in the total density. We use these results, along with the predictions of big bang nucleosynthesis, to place bounds on these corrections and especially the patch size of discrete quantum gravity states.

  14. Electron screening and its effects on big-bang nucleosynthesis

    International Nuclear Information System (INIS)

    Wang Biao; Bertulani, C. A.; Balantekin, A. B.

    2011-01-01

    We study the effects of electron screening on nuclear reaction rates occurring during the big-bang nucleosynthesis epoch. The sensitivity of the predicted elemental abundances on electron screening is studied in detail. It is shown that electron screening does not produce noticeable results in the abundances unless the traditional Debye-Hueckel model for the treatment of electron screening in stellar environments is enhanced by several orders of magnitude. This work rules out electron screening as a relevant ingredient to big-bang nucleosynthesis, confirming a previous study [see Itoh et al., Astrophys. J. 488, 507 (1997)] and ruling out exotic possibilities for the treatment of screening beyond the mean-field theoretical approach.

  15. Lepton asymmetry, neutrino spectral distortions, and big bang nucleosynthesis

    Science.gov (United States)

    Grohs, E.; Fuller, George M.; Kishimoto, C. T.; Paris, Mark W.

    2017-03-01

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

  16. Was the Universe actually radiation dominated prior to nucleosynthesis?

    Science.gov (United States)

    Giblin, John T.; Kane, Gordon; Nesbit, Eva; Watson, Scott; Zhao, Yue

    2017-08-01

    Maybe not. String theory approaches to both beyond the Standard Model and inflationary model building generically predict the existence of scalars (moduli) that are light compared to the scale of quantum gravity. These moduli become displaced from their low energy minima in the early Universe and lead to a prolonged matter-dominated epoch prior to big bang nucleosynthesis (BBN). In this paper, we examine whether nonperturbative effects such as parametric resonance or tachyonic instabilities can shorten, or even eliminate, the moduli condensate and matter-dominated epoch. Such effects depend crucially on the strength of the couplings, and we find that unless the moduli become strongly coupled, the matter-dominated epoch is unavoidable. In particular, we find that in string and M-theory compactifications where the lightest moduli are near the TeV scale, a matter-dominated epoch will persist until the time of big bang nucleosynthesis.

  17. Challenges to the standard model of Big Bang nucleosynthesis

    International Nuclear Information System (INIS)

    Steigman, G.

    1993-01-01

    Big Bang nucleosynthesis provides a unique probe of the early evolution of the Universe and a crucial test of the consistency of the standard hot Big Bang cosmological model. Although the primordial abundances of 2 H, 3 He, 4 He, and 7 Li inferred from current observational data are in agreement with those predicted by Big Bang nucleosynthesis, recent analysis has severely restricted the consistent range for the nucleon-to-photon ratio: 3.7 ≤ η 10 ≤ 4.0. Increased accuracy in the estimate of primordial 4 he and observations of Be and B in Pop II stars are offering new challenges to the standard model and suggest that no new light particles may be allowed (N ν BBN ≤ 3.0, where N ν is the number of equivalent light neutrinos). 23 refs

  18. R-process nucleosynthesis: a dynamical model

    Energy Technology Data Exchange (ETDEWEB)

    Hillebrandt, W; Takahashi, K [Technische Hochschule Darmstadt (Germany, F.R.). Inst. fuer Kernphysik; Kodama, T [Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro

    1976-10-01

    The synthesis of heavy and neutron-rich elements (with the mass number A > approximately 70) is reconsidered in the framework of a dynamical supernova model. The synthesis equation for the rapid neutron-capture (or, the r-) process and the hydrodynamical equations for the supernova explosion are solved simultaneously. Improved systematics of nuclear parameters are used, and the energy release due to ..beta..-decays as well as the energy loss due to neutrinos is taken into account. It is shown that the observed solar-system abundance curve can be reproduced fairly well by assuming only one supernova event on a time-scale of the order of 1 s. However there are still some discrepancies which may be explained by uncertainties in the nuclear data used.

  19. Monte Carlo calculations for r-process nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mumpower, Matthew Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-12

    A Monte Carlo framework is developed for exploring the impact of nuclear model uncertainties on the formation of the heavy elements. Mass measurements tightly constrain the macroscopic sector of FRDM2012. For r-process nucleosynthesis, it is necessary to understand the microscopic physics of the nuclear model employed. A combined approach of measurements and a deeper understanding of the microphysics is thus warranted to elucidate the site of the r-process.

  20. Nucleosynthesis of heavy elements by the photonuclear reaction

    International Nuclear Information System (INIS)

    Hayakawa, Takehito

    2002-01-01

    Nucleosynthesis of heavy elements is important for understanding of the site mechanism in the stellar and cosmochronology. The nuclei heavier than iron have been synthesized mainly by the s-process and the β-decay after the r-process. The light isotope p-nuclei produced by the photonuclear reaction in Type II supernovae explosions. In order to understand the role of each process, the ratios of the processes are calculated. I propose the experimental plan using the photon sources. (author)

  1. Towards the kinetic theory of inequilibrium cosmological nucleosynthesis

    International Nuclear Information System (INIS)

    Fillipov, S.S.; Sedelnikov, E.V.; Khlopov, M.Yu.

    1993-07-01

    The aim of the paper is to elaborate the framework for the possible effects of nucleosynthesis by inequilirbium particles on the radiation dominance stage. Based on such an analysis the sensitivity of the astrophysical data to the presence of the sources of inequilibrium particles in the early Universe can be studied, thus providing an effective tool to probe cosmological effects of syperhight energy physics. 6 refs

  2. Neutrinos and Nucleosynthesis in Hot and Dense Matter

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, George [Univ. of California, San Diego, CA (United States)

    2016-01-14

    The Topical Collaboration for Neutrinos and Nucleosynthesis in Hot and Dense matter brought together researchers from a variety of nuclear science specialties and a number of institutions to address nuclear physics and neutrino physics problems associated with dense matter and the origin of the elements. See attached final technical reports for (1) the UCSD award and (2) a copy of the report for the whole TC

  3. Possible evidence for dark radiation from Big Bang Nucleosynthesis data

    Energy Technology Data Exchange (ETDEWEB)

    Flambaum, V.V. [New South Wales Univ., School of Physics, Sydney NSW (Australia); Argonne National Laboratory, Physics Div., Argonne, IL (United States); Shuryak, E.V. [State University of New York Stony Brook, Dept. of Physics and Astronomy, NY (United States)

    2006-06-15

    We address the emerging discrepancy between the Big Bang Nucleosynthesis data and standard cosmology, which asks for a bit longer evolution time. If this effect is real, one possible implication (in a framework of brane cosmology model) is that there is a 'dark radiation' component which is negative and makes few percents of ordinary matter density. If so, all scales of this model can be fixed, provided brane-to-bulk leakage problem is solved. (authors)

  4. Possible evidence for dark radiation from Big Bang Nucleosynthesis data

    International Nuclear Information System (INIS)

    Flambaum, V.V.; Shuryak, E.V.

    2006-01-01

    We address the emerging discrepancy between the Big Bang Nucleosynthesis data and standard cosmology, which asks for a bit longer evolution time. If this effect is real, one possible implication (in a framework of brane cosmology model) is that there is a 'dark radiation' component which is negative and makes few percents of ordinary matter density. If so, all scales of this model can be fixed, provided brane-to-bulk leakage problem is solved. (authors)

  5. The gravitino-stau scenario after catalyzed big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kersten, Joern [The Abdus Salam ICTP, Strada Costiera 11, 34014 Trieste (Italy); Schmidt-Hoberg, Kai, E-mail: jkersten@ictp.it, E-mail: kai.schmidt-hoberg@ph.tum.de, E-mail: kai.schmidt.hoberg@desy.de [Physik-Department T30, Technische Universitaet Muenchen, James-Franck-Strasse, 85748 Garching (Germany)

    2008-01-15

    We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m{sub 1/2}. As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints.

  6. The gravitino-stau scenario after catalyzed big bang nucleosynthesis

    Science.gov (United States)

    Kersten, Jörn; Schmidt-Hoberg, Kai

    2008-01-01

    We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m1/2. As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints.

  7. The gravitino–stau scenario after catalyzed big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Kersten, Jörn; Schmidt-Hoberg, Kai

    2008-01-01

    We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m 1/2 . As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints

  8. Neutron capture cross sections of Kr

    Directory of Open Access Journals (Sweden)

    Fiebiger Stefan

    2017-01-01

    Full Text Available Neutron capture and β− -decay are competing branches of the s-process nucleosynthesis path at 85Kr [1], which makes it an important branching point. The knowledge of its neutron capture cross section is therefore essential to constrain stellar models of nucleosynthesis. Despite its importance for different fields, no direct measurement of the cross section of 85Kr in the keV-regime has been performed. The currently reported uncertainties are still in the order of 50% [2, 3]. Neutron capture cross section measurements on a 4% enriched 85Kr gas enclosed in a stainless steel cylinder were performed at Los Alamos National Laboratory (LANL using the Detector for Advanced Neutron Capture Experiments (DANCE. 85Kr is radioactive isotope with a half life of 10.8 years. As this was a low-enrichment sample, the main contaminants, the stable krypton isotopes 83Kr and 86Kr, were also investigated. The material was highly enriched and contained in pressurized stainless steel spheres.

  9. Nucleosynthesis and remnants in massive stars of solar metallicity

    International Nuclear Information System (INIS)

    Woosley, S.E.; Heger, A.

    2007-01-01

    Hans Bethe contributed in many ways to our understanding of the supernovae that happen in massive stars, but, to this day, a first principles model of how the explosion is energized is lacking. Nevertheless, a quantitative theory of nucleosynthesis is possible. We present a survey of the nucleosynthesis that occurs in 32 stars of solar metallicity in the mass range 12-120M sun . The most recent set of solar abundances, opacities, mass loss rates, and current estimates of nuclear reaction rates are employed. Restrictions on the mass cut and explosion energy of the supernovae based upon nucleosynthesis, measured neutron star masses, and light curves are discussed and applied. The nucleosynthetic results, when integrated over a Salpeter initial mass function (IMF), agree quite well with what is seen in the sun. We discuss in some detail the production of the long lived radioactivities, 26 Al and 60 Fe, and why recent model-based estimates of the ratio 60 Fe/ 26 Al are overly large compared with what satellites have observed. A major source of the discrepancy is the uncertain nuclear cross sections for the creation and destruction of these unstable isotopes

  10. S-process nucleosynthesis in low mass AGB Stars: do we really need an improved determination of the 13C(α, n)16O reaction rate?

    International Nuclear Information System (INIS)

    Cristallo, S.; Straniero, O.; Gallino, R.

    2005-01-01

    Thermally pulsing Asymptotic Giant Branch stars are responsible for the nucleosynthesis of the main component of the cosmic s-elements. The most important neutron source is the 13 C(α, n) 16 O reaction. Owing to the presence of a subthreshold resonance, the low energy extrapolation is a rather complex task. The rate quoted in the literature differ up to a factor of 4 at typical stellar energies. The latest improvements in computer power allows us to calculate the evolution of TP-AGB stars coupled with a full nuclear network, extending from hydrogen to lead. Here we discuss the effects of the variation of the 13 C(α, n) 16 O rate on the predicted neutron capture nucleosynthesis

  11. Simultaneous solution to the 6Li and 7Li big bang nucleosynthesis problems from a long-lived negatively charged leptonic particle

    International Nuclear Information System (INIS)

    Kusakabe, Motohiko; Kajino, Toshitaka; Boyd, Richard N.; Yoshida, Takashi; Mathews, Grant J.

    2007-01-01

    The 6 Li abundance observed in metal-poor halo stars exhibits a plateau similar to that for 7 Li suggesting a primordial origin. However, the observed abundance of 6 Li is a factor of 10 3 larger and that of 7 Li is a factor of 3 lower than the abundances predicted in the standard big bang when the baryon-to-photon ratio is fixed by Wilkinson microwave anisotropy probe. Here we show that both of these abundance anomalies can be explained by the existence of a long-lived massive, negatively charged leptonic particle during nucleosynthesis. Such particles would capture onto the synthesized nuclei thereby reducing the reaction Coulomb barriers and opening new transfer reaction possibilities, and catalyzing a second round of big bang nucleosynthesis. This novel solution to both of the Li problems can be achieved with or without the additional effects of stellar destruction

  12. Optimization of a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications in nucleosynthesis experiments

    Science.gov (United States)

    Gatu Johnson, M.; Casey, D. T.; Hohenberger, M.; Zylstra, A. B.; Bacher, A.; Brune, C. R.; Bionta, R. M.; Craxton, R. S.; Ellison, C. L.; Farrell, M.; Frenje, J. A.; Garbett, W.; Garcia, E. M.; Grim, G. P.; Hartouni, E.; Hatarik, R.; Herrmann, H. W.; Hohensee, M.; Holunga, D. M.; Hoppe, M.; Jackson, M.; Kabadi, N.; Khan, S. F.; Kilkenny, J. D.; Kohut, T. R.; Lahmann, B.; Le, H. P.; Li, C. K.; Masse, L.; McKenty, P. W.; McNabb, D. P.; Nikroo, A.; Parham, T. G.; Parker, C. E.; Petrasso, R. D.; Pino, J.; Remington, B.; Rice, N. G.; Rinderknecht, H. G.; Rosenberg, M. J.; Sanchez, J.; Sayre, D. B.; Schoff, M. E.; Shuldberg, C. M.; Séguin, F. H.; Sio, H.; Walters, Z. B.; Whitley, H. D.

    2018-05-01

    Polar-direct-drive exploding pushers are used as a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications including diagnostic calibration, nuclear security, backlighting, electron-ion equilibration, and nucleosynthesis-relevant experiments. In this paper, two different paths to improving the performance of this platform are explored: (i) optimizing the laser drive, and (ii) optimizing the target. While the present study is specifically geared towards nucleosynthesis experiments, the results are generally applicable. Example data from T2/3He-gas-filled implosions with trace deuterium are used to show that yield and ion temperature (Tion) from 1.6 mm-outer-diameter thin-glass-shell capsule implosions are improved at a set laser energy by switching from a ramped to a square laser pulse shape, and that increased laser energy further improves yield and Tion, although by factors lower than predicted by 1 D simulations. Using data from D2/3He-gas-filled implosions, yield at a set Tion is experimentally verified to increase with capsule size. Uniform D3He-proton spectra from 3 mm-outer-diameter CH shell implosions demonstrate the utility of this platform for studying charged-particle-producing reactions relevant to stellar nucleosynthesis.

  13. The r-process nucleosynthesis during the decompression of neutron star crust material

    Energy Technology Data Exchange (ETDEWEB)

    Goriely, S. [Institut d' Astronomie et d' Astrophysique, CP-226, Université Libre de Bruxelles, 1050 Brussels (Belgium); Bauswein, A. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece and Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching (Germany); Janka, H.-T. [Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching (Germany); Sida, J.-L.; Lemaître, J.-F.; Panebianco, S. [C.E.A. Saclay, Irfu/Service de Physique Nucléaire, 91191 Gif-sur-Yvette (France); Dubray, N.; Hilaire, S. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-05-02

    About half of the nuclei heavier than iron observed in nature are produced by the so-called rapid neutron capture process, or r-process, of nucleosynthesis. The identification of the astrophysics site and the specific conditions in which the r-process takes place remains, however, one of the still-unsolved mysteries of modern astrophysics. Another underlying difficulty associated with our understanding of the r-process concerns the uncertainties in the predictions of nuclear properties for the few thousands exotic neutron-rich nuclei involved, for which essentially no experimental data exist. The present paper emphasizes some important future challenges faced by nuclear physics in this problem, particularly in the determination of the nuclear structure properties of exotic neutron-rich nuclei as well as their radiative neutron capture rates and their fission probabilities. These quantities are particularly relevant to determine the composition of the matter resulting from the r-process. Both the astrophysics and the nuclear physics difficulties are critically reviewed with special attention paid to the r-process taking place during the decompression of neutron star matter following the merging of two neutron stars.

  14. Resonance capture reactions with a total energy detector

    International Nuclear Information System (INIS)

    Macklin, R.L.

    1978-01-01

    The determination of nuclear reaction rates is considered; the Moxon--Rae detector and pulse height weighting are reviewed. This method has been especially useful in measuring (n,γ) cross sections. Strength functions and level spacing can be derived from (n,γ) yields. The relevance of neutron capture data to astrophysical nucleosynthesis is pointed out. The total gamma energy detection method has been applied successfully to radiative neutron capture cross section measurements. A bibliography of most of the published papers reporting neutron capture cross sections measured by the pulse height weighting technique is included. 55 references

  15. Capture and photonuclear reaction rates involving charged-particles: Impacts of nuclear ingredients and future measurement on ELI-NP

    Directory of Open Access Journals (Sweden)

    Xu Y.

    2018-01-01

    Full Text Available The astrophysical p-process is an important way of nucleosynthesis to produce the stable and proton-rich nuclei beyond Fe which can not be reached by the s- and r-processes. In the present study, the impact of nuclear ingredients, especially the nuclear potential, level density and strength function, to the astrophysical re-action rates of (p,γ, (α,γ, (γ,p, and (γ,α reactions are systematically studied. The calculations are performed basad on the modern reaction code TALYS for about 3000 stable and proton-rich nuclei with 12≤Z≤110. In particular, both of the Wood-Saxon potential and the microscopic folding potential are taken into account. It is found that both the capture and photonuclear reaction rates are very sensitive to the nuclear potential, thus the better determination of nuclear potential would be important to reduce the uncertainties of reaction rates. Meanwhile, the Extreme Light Infrastructure-Nuclear Physics (ELI-NP facility is being developed, which will provide the great opportunity to experimentally study the photonuclear reactions in p-process. Simulations of the experimental setup for the measurements of the photonuclear reactions 96Ru(γ,p and 96Ru(γ,α are performed. It is shown that the experiments of photonuclear reactions in p-process based on ELI-NP are quite promising.

  16. Capture and photonuclear reaction rates involving charged-particles: Impacts of nuclear ingredients and future measurement on ELI-NP

    Science.gov (United States)

    Xu, Y.; Goriely, S.; Balabanski, D. L.; Chesnevskaya, S.; Guardo, G. L.; La Cognata, M.; Lan, H. Y.; Lattuada, D.; Luo, W.; Matei, C.

    2018-05-01

    The astrophysical p-process is an important way of nucleosynthesis to produce the stable and proton-rich nuclei beyond Fe which can not be reached by the s- and r-processes. In the present study, the impact of nuclear ingredients, especially the nuclear potential, level density and strength function, to the astrophysical re-action rates of (p,γ), (α,γ), (γ,p), and (γ,α) reactions are systematically studied. The calculations are performed basad on the modern reaction code TALYS for about 3000 stable and proton-rich nuclei with 12≤Z≤110. In particular, both of the Wood-Saxon potential and the microscopic folding potential are taken into account. It is found that both the capture and photonuclear reaction rates are very sensitive to the nuclear potential, thus the better determination of nuclear potential would be important to reduce the uncertainties of reaction rates. Meanwhile, the Extreme Light Infrastructure-Nuclear Physics (ELI-NP) facility is being developed, which will provide the great opportunity to experimentally study the photonuclear reactions in p-process. Simulations of the experimental setup for the measurements of the photonuclear reactions 96Ru(γ,p) and 96Ru(γ,α) are performed. It is shown that the experiments of photonuclear reactions in p-process based on ELI-NP are quite promising.

  17. Neutron capture cross section of $^{93}$Zr

    CERN Document Server

    We propose to measure the neutron capture cross section of the radioactive isotope $^{93}$Zr. This project aims at the substantial improvement of existing results for applications in nuclear astrophysics and emerging nuclear technologies. In particular, the superior quality of the data that can be obtained at n_TOF will allow on one side a better characterization of s-process nucleosynthesis and on the other side a more accurate material balance in systems for transmutation of nuclear waste, given that this radioactive isotope is widely present in fission products.

  18. Observational limits on the magnetic-monopole structure of protons

    International Nuclear Information System (INIS)

    Broderick, J.J.; Ficenec, J.R.; Teplitz, D.C.; Teplitz, V.L.

    1979-01-01

    We report the results of a search for absorption of 42-cm radiation in neutral galactic hydrogen. One explanation of a positive result would be the existence of a type of anomalous proton whose magnetic moment arises from a distribution of magnetic charge rather than from a distribution of circulating currents. No absorption of 42-cm radiation was seen; this implies an upper limit of 2.3 x 10 -4 for the abundance of this type of anomalous proton relative to protons which radiate at 21 cm. The observed absence of anomalous protons also implies an absence of primordial anomalous protons since they could not have been swept up by heavier elements during cosmic nucleosynthesis. The observation is sensitive only to anomalous protons with exactly the same value for their magnetic moment that conventional ones have

  19. Effects of an energy broadened proton beam on the neutron distribution for the "7Li(p,n)"7Be reaction near threshold

    International Nuclear Information System (INIS)

    Shor, A.; Eisen, Y.; Berkovits, D.; Hirsh, T.; Feinberg, G.; Friedman, M.; Paul, M.; Krasa, A.; Giorginis, G.; Plompen, A.

    2011-01-01

    A common method for simulating the thermal neutron conditions in the stellar interior is based on the "7Li(p,n)"7Be reaction near threshold energy. Maxwellian-averaged neutron capture cross-sections of mean energy 25 keV, relevant to the s-process nucleosynthesis, are measured at existing Van-de-Graaff (VdG) proton accelerators. Soreq NRC Applied Research superconducting linear Accelerator Facility (SARAF) phase 1 is in its final stage of commissioning. Maxwellian averaged neutron capture cross-section measurements are planned to be conducted using a forced-flow closed-loop liquid-lithium target (LiLiT). The proton beam energy spread of RF linear accelerators, such as SARAF, is typically larger than the spread of proton beams of VdG accelerators. The energy spread of SARAF proton beam at 1912 keV is calculated to be of the order of 20-40 keV FWHM as compared to about 3 keV FWHM for VdG accelerators. For simulating the SARAF proton beam we performed an experiment at the IRMM-Geel VdG using a gold foil degrader positioned before the LiF target. This degrader shifts the mean proton energy to 1912 keV and it broadens the proton beam energy to values simulating the spread of the proton beam at SARAF. For calibrating the cross-sections we also performed a "7Li(p,n)"7Be experiment without the gold foil degrader at a proton energy of 1912 keV. The VdG was operated in a pulse mode and the neutron energies were determined by time-of-flight measurements using "6Li glass detectors. Detector efficiencies were obtained by Monte Carlo calculations. We present our study and compare the results for both narrow and broad energy proton beams. It is shown that the energy distribution for the broad-energy beam with a spread of 15 keV is similar to that of the distribution of the narrow energy beam and they peak nearly at the same energy. The broad-energy distribution has a tail extending to higher energies than that of the narrow-energy beam. It appears also that the neutron

  20. Nuclear weak interactions, supernova nucleosynthesis and neutrino oscillation

    Science.gov (United States)

    Kajino, Toshitaka

    2013-07-01

    We study the nuclear weak response in light-to-heavy mass nuclei and calculate neutrino-nucleus cross sections. We apply these cross sections to the explosive nucleosynthesis in core-collapse supernovae and find that several isotopes of rare elements 7Li, 11B, 138La, 180Ta and several others are predominantly produced by the neutrino-process nucleosynthesis. We discuss how to determine the suitable neutrino spectra of three different flavors and their anti-particles in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. Light-mass nuclei like 7Li and 11B, which are produced in outer He-layer, are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect, while heavy-mass nuclei like 138La, 180Ta and r-process elements, which are produced in the inner O-Ne-Mg layer or the atmosphere of proto-neutron star, are likely to be free from the MSW effect. Using such a different nature of the neutrino-process nucleosynthesis, we study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the unknown neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

  1. Persistent Tensions in Big Bang Nucleosynthesis and Windows on New Physics

    International Nuclear Information System (INIS)

    Tytler, David

    2009-01-01

    Now that we know the baryon to photon ratio to 5% from the cosmic microwave background, Big Bang Nucleosynthesis using standard physics predicts the abundances of five light nuclei with no free parameters. The Deuterium to Hydrogen ratio measured towards quasars agrees with the prediction to within 10%, but there has been tension verging on disagreement between the estimates of the primordial abundances of 4 He and especially 7 Li since 1996. While some recent 4 He measurements agree, the large majority of measurements over the last 30 years have been smaller than the predictions. For 7 Li, the measurements are sufficiently accurate to show that the 7 Li/H in old stars in the halo of our Galaxy is a factor of 3-4 below the predicted ratio. Perhaps stars with a variety of masses have destroyed the same amount of 7 Li, or we already have evidence for new physics. Improved measurements of the primordial abundances could lead to a detection of a wide variety of new physics because BBN is sensitive to all four forces. Examples include new particles that were relativistic during BBN, decaying particles that change the abundances after BBN or a large net lepton number for the universe that changed the neutron to proton ratio and hence the abundances.

  2. Dirac cosmology and the onset of galactic nucleosynthesis

    International Nuclear Information System (INIS)

    Adams, P.J.; Canuto, V.

    1976-01-01

    Recently Browne and Berman determined the onset of nucleosynthesis of heavy elements in the galaxy to be about 18 billion years ago based on the weak decay of rhenium 187 to osmium 187. This age is appreciably larger than the 13 billion years determined from the uranium decay chains. It is also larger than the 16 billion year age of the Universe determined from the standard model by the latest values of the Hubble constant and deceleration parameter. This letter points out that this discrepancy is predicted by Dirac's cosmology and derives from a time-varying weak coupling constant. (Auth.)

  3. Big bang photosynthesis and pregalactic nucleosynthesis of light elements

    International Nuclear Information System (INIS)

    Audouze, J.; Lindley, D.; Silk, J.; and Laboratoire Rene Bernas, Orsay, France)

    1985-01-01

    Two nonstandard scenarios for pregalactic synthesis of the light elements ( 2 H, 3 He, 4 He, and 7 Li) are developed. Big bang photosynthesis occurs if energetic photons, produced by the decay of massive neutrinos or gravitinos, partially photodisintegrate 4 He (formed in the standard hot big bang) to produce 2 H and 3 He. In this case, primordial nucleosynthesis no longer constrains the baryon density of the universe, or the number of neutrino species. Alternatively, one may dispense partially or completely with the hot big bang and produce the light elements by bombardment of primordial gas, provided that 4 He is synthesized by a later generation of massive stars

  4. Quark mass variation constraints from Big Bang nucleosynthesis

    International Nuclear Information System (INIS)

    Bedaque, Paulo F.; Luu, Thomas; Platter, Lucas

    2011-01-01

    We study the impact on the primordial abundances of light elements created by a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way, we use lattice QCD data and a hierarchy of effective field theories. We find that the measured 4 He abundances put a bound of -1% q /m q q /m q .

  5. Big bang photosynthesis and pregalactic nucleosynthesis of light elements

    Science.gov (United States)

    Audouze, J.; Lindley, D.; Silk, J.

    1985-01-01

    Two nonstandard scenarios for pregalactic synthesis of the light elements (H-2, He-3, He-4, and Li-7) are developed. Big bang photosynthesis occurs if energetic photons, produced by the decay of massive neutrinos or gravitinos, partially photodisintegrate He-4 (formed in the standard hot big bang) to produce H-2 and He-3. In this case, primordial nucleosynthesis no longer constrains the baryon density of the universe, or the number of neutrino species. Alternatively, one may dispense partially or completely with the hot big bang and produce the light elements by bombardment of primordial gas, provided that He-4 is synthesized by a later generation of massive stars.

  6. Evolution of the early universe and big-bang nucleosynthesis

    International Nuclear Information System (INIS)

    Kajino, T.

    1995-01-01

    Cosmological phase transition can create strongly inhomogeneous baryon density distribution. Inhomogeneous big-bang model for primordial nucleosynthesis allows higher universal mass density parameter of baryons than the standard model does, which is marginally consistent with recent astronomical suggestion that some kind of dark matter is made of baryons. Enhanced heavy-element abundances in halo dwarfs is shown to be an observational signature for the inhomogeneous big-bang model. The studies of radioactive nuclear reactions help predict the theoretical abundances of these elements more precisely. (author). 53 refs., 8 figs

  7. Collective neutrino oscillations and r-process nucleosynthesis in supernovae

    Science.gov (United States)

    Duan, Huaiyu

    2012-10-01

    Neutrinos can oscillate collectively in a core-collapse supernova. This phenomenon can occur much deeper inside the supernova envelope than what is predicted from the conventional matter-induced Mikheyev-Smirnov-Wolfenstein effect, and hence may have an impact on nucleosynthesis. The oscillation patterns and the r-process yields are sensitive to the details of the emitted neutrino fluxes, the sign of the neutrino mass hierarchy, the modeling of neutrino oscillations and the astrophysical conditions. The effects of collective neutrino oscillations on the r-process will be illustrated using representative late-time neutrino spectra and outflow models.

  8. Chiral-symmetry order parameter, the lattice, and nucleosynthesis

    International Nuclear Information System (INIS)

    McLerran, L.

    1987-01-01

    I discuss an order parameter for the chiral-symmetry restoration phase transition which may be useful in computations of big-bang nucleosynthesis, a phenomenon which requires a finite baryon-number density. This parameter is strictly speaking an order parameter in the large-N limit, and distinguishes between a parity-doubled and a massless-fermion realization of chiral-symmetry restoration. This order parameter may be evaluated at a zero net baryon-number density at finite temperature, and is useful as long as the baryon chemical potential μ is much less than the temperature T

  9. BIG BANG NUCLEOSYNTHESIS WITH A NON-MAXWELLIAN DISTRIBUTION

    International Nuclear Information System (INIS)

    Bertulani, C. A.; Fuqua, J.; Hussein, M. S.

    2013-01-01

    The abundances of light elements based on the big bang nucleosynthesis model are calculated using the Tsallis non-extensive statistics. The impact of the variation of the non-extensive parameter q from the unity value is compared to observations and to the abundance yields from the standard big bang model. We find large differences between the reaction rates and the abundance of light elements calculated with the extensive and the non-extensive statistics. We found that the observations are consistent with a non-extensive parameter q = 1 - 0.12 +0.05 , indicating that a large deviation from the Boltzmann-Gibbs statistics (q = 1) is highly unlikely.

  10. Adiabatic capture and debunching

    International Nuclear Information System (INIS)

    Ng, K.Y.

    2012-01-01

    In the study of beam preparation for the g-2 experiment, adiabatic debunching and adiabatic capture are revisited. The voltage programs for these adiabbatic processes are derived and their properties discussed. Comparison is made with some other form of adiabatic capture program. The muon g-2 experiment at Fermilab calls for intense proton bunches for the creation of muons. A booster batch of 84 bunches is injected into the Recycler Ring, where it is debunched and captured into 4 intense bunches with the 2.5-MHz rf. The experiment requires short bunches with total width less than 100 ns. The transport line from the Recycler to the muon-production target has a low momentum aperture of ∼ ±22 MeV. Thus each of the 4 intense proton bunches required to have an emittance less than ∼ 3.46 eVs. The incoming booster bunches have total emittance ∼ 8.4 eVs, or each one with an emittance ∼ 0.1 eVs. However, there is always emittance increase when the 84 booster bunches are debunched. There will be even larger emittance increase during adiabatic capture into the buckets of the 2.5-MHz rf. In addition, the incoming booster bunches may have emittances larger than 0.1 eVs. In this article, we will concentrate on the analysis of the adiabatic capture process with the intention of preserving the beam emittance as much as possible. At this moment, beam preparation experiment is being performed at the Main Injector. Since the Main Injector and the Recycler Ring have roughly the same lattice properties, we are referring to adiabatic capture in the Main Injector instead in our discussions.

  11. Radiative muon capture on hydrogen

    International Nuclear Information System (INIS)

    Bertl, W.; Ahmad, S.; Chen, C.Q.; Gumplinger, P.; Hasinoff, M.D.; Larabee, A.J.; Sample, D.G.; Schott, W.; Wright, D.H.; Armstrong, D.S.; Blecher, M.; Azuelos, G.; Depommier, P.; Jonkmans, G.; Gorringe, T.P.; Henderson, R.; Macdonald, J.A.; Poutissou, J.M.; Poutissou, R.; Von Egidy, T.; Zhang, N.S.; Robertson, B.D.

    1992-01-01

    The radiative capture of negative muons by protons can be used to measure the weak induced pseudoscalar form factor. Brief arguments why this method is preferable to ordinary muon capture are given followed by a discussion of the experimental difficulties. The solution to these problems as attempted by experiment no. 452 at TRIUMF is presented together with preliminary results from the first run in August 1990. An outlook on the expected final precision and the experimental schedule is also given. (orig.)

  12. Electron capture rate of a composite of partially ionized atomic nuclei

    International Nuclear Information System (INIS)

    Yokoi, K.; Takahashi, K.

    1979-01-01

    Electron captures (or more generally β-transitions) are known to play key roles at various stages of stellar evolution and in many nucleosynthesis processes. With decreasing temperatures and densities, the bound electron captures start to compete with the free electron captures, and eventually in the low-temperature, low-density limit the total capture rate shall converge to that of the orbital electrons observed in laboratory. The authors calculate the occupation probabilities of the electron orbits and the electron capture rates in a mixture of atoms and ions which are supposedly under a chemical equilibrium. (orig./AH)

  13. Gravitational capture

    International Nuclear Information System (INIS)

    Bondi, H.

    1979-01-01

    In spite of the strength of gravitational focres between celestial bodies, gravitational capture is not a simple concept. The principles of conservation of linear momentum and of conservation of angular momentum, always impose severe constraints, while conservation of energy and the vital distinction between dissipative and non-dissipative systems allows one to rule out capture in a wide variety of cases. In complex systems especially those without dissipation, long dwell time is a more significant concept than permanent capture. (author)

  14. Chemical evolution, stellar nucleosynthesis and a variable star formation rate

    International Nuclear Information System (INIS)

    Olive, K.A.; Thielemann, F.K.; Truran, J.W.

    1986-04-01

    The effects of a decreasing star formation rate (SFR) on the galactic abundances of elements produced in massive stars (M ≥ 10 Msub solar). On the basis of a straightforward model of galactic evolution, a relation between the upper mass limit of type II supernovae (M/sub SN/) contributing to chemical evolution and the decline of the SFR (tau) is derived, when the oxygen abundance is determined only by massive stars. The additional requirement that all intermediate mass elements (Ne-Ti), which are also predominantly due to nucleosynthesis in massive stars, are produced in solar proportions leads to a unique value of M/sub SN/ and tau. The application of this method with abundance yields from Arnett (1978) and Woosley and Weaver (1986) resuults, however, in contradicting solutions: M/sub SN/ ≅ 45 Msub solar, tau = ∞, and M/sub SN/ ≅ 15 Msub solar, tau = 3 x 10 9 y. Thus, in order that this approach provide an effective probe of the SFR over the history of our galaxy it is essential that converging and more accurate predictions of the consequences of stellar and supernova nucleosynthesis will be forthcoming. 54 refs., 2 figs., 2 tabs

  15. Challenges in nucleosynthesis of trans-iron elements

    International Nuclear Information System (INIS)

    Rauscher, T.

    2014-01-01

    Nucleosynthesis beyond Fe poses additional challenges not encountered when studying astrophysical processes involving light nuclei. Astrophysical sites and conditions are not well known for some of the processes involved. On the nuclear physics side, different approaches are required, both in theory and experiment. The main differences and most important considerations are presented for a selection of nucleosynthesis processes and reactions, specifically the s-, r-, γ-, and νp-processes. Among the discussed issues are uncertainties in sites and production conditions, the difference between laboratory and stellar rates, reaction mechanisms, important transitions, thermal population of excited states, and uncertainty estimates for stellar rates. The utility and limitations of indirect experimental approaches are also addressed. The presentation should not be viewed as confining the discussed problems to the specific processes. The intention is to generally introduce the concepts and possible pitfalls along with some examples. Similar problems may apply to further astrophysical processes involving nuclei from the Fe region upward and/or at high plasma temperatures. The framework and strategies presented here are intended to aid the conception of future experimental and theoretical approaches

  16. Big-bang nucleosynthesis in the new cosmology

    International Nuclear Information System (INIS)

    Fields, B.D.

    2005-01-01

    Big bang nucleosynthesis (BBN) describes the production of the lightest elements in the first minutes of cosmic time. I will review the physics of cosmological element production, and the observations of the primordial element abundances. The comparison between theory and observation has heretofore provided our earliest probe of the universe, and given the best measure of the cosmic baryon content. However, BBN has now taken a new role in cosmology, in light of new precision measurements of the cosmic microwave background (CMB). Recent CMB anisotropy data yield a wealth of cosmological parameters; in particular, the baryon-to-photon ratio η = n B /n γ is measured to high precision. The confrontation between the BBN and CMB 'baryometers' poses a new and stringent test of the standard cosmology; the status of this test will be discussed. Moreover, it is now possible to recast the role of BBN by using the CMB to fix the baryon density and even some light element abundances. This strategy sharpens BBN into a more powerful probe of early universe physics, and of galactic nucleosynthesis processes. The impact of the CMB results on particle physics beyond the Standard Model, and on non-standard cosmology, will be illustrated. Prospects for improvement of these bounds via additional astronomical observations and nuclear experiments will be discussed, as will the lingering 'lithium problem.' (author)

  17. Giant resonance effects in radiative capture

    International Nuclear Information System (INIS)

    Snover, K.A.

    1979-01-01

    The technique of capture reaction studies of giant resonance properties is described, and a number of examples are given. Most of the recent work of interest has been in proton capture, in part because of the great utility (and availability) of polarized beams; most of the discussion concerns this reaction. Alpha capture, which has been a useful tool for exploring isoscalar E2 strength, and neutron capture are, however, also treated. 46 references, 14 figures

  18. Proton linacs for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Lennox, A.J.

    1993-08-01

    Recent advances in the ability to deliver boron-containing drugs to brain tumors have generated interest in ∼4 MeV linacs as sources of epithermal neutrons for radiation therapy. In addition, fast neutron therapy facilities have been studying methods to moderate their beams to take advantage of the high cross section for epithermal neutrons on boron-10. This paper describes the technical issues involved in each approach and presents the motivation for undertaking such studies using the Fermilab linac. the problems which must be solved before therapy can begin are outlined. Status of preparatory work and results of preliminary measurements are presented

  19. Nucleosynthesis Modes in the High-Entropy-Wind Scenario of Type II Supernovae

    International Nuclear Information System (INIS)

    Farouqi, K.; Kratz, K.-L.; Cowan, J. J.; Mashonkina, L. I.; Pfeiffer, B.; Sneden, C.; Thielemann, F.-K.; Truran, J. W.

    2008-01-01

    In an attempt to constrain the astrophysical conditions for the nucleosynthesis of the classical r-process elements beyond Fe, we have performed large-scale dynamical network calculations within the model of an adiabatically expanding high- entropy wind (HEW) of type II supernovae (SN II). A superposition of several entropy-components (S) with model-inherent weightings results in an excellent reproduction of the overall Solar System (SS) isotopic r-process residuals (N r,· ), as well as the more recent observations of elemental abundances of metal-poor, r-process rich halo stars in the early Galaxy. For the heavy r-process elements beyond Sn, our HEW model predicts a robust abundance pattern up to the Th, U r-chronometer region. For the lighter neutron-capture region, an S-dependent superposition of (i) a normal α-component directly producing stable nuclei, including s-only isotopes, and (ii) a component from a neutron-rich α-freezeout followed by the rapid recapture of β-delayed neutrons (βdnrpar; emitted from the far-unstable seed nuclei is indicated. In agreement with several recent halo-star observations in the 60< A<110 region, our HEW model confirms a Z-dependent non-correlation, respectively partial correlation with the heavier ''main'' r-process elements

  20. Electron capture in asymmetric collisions

    International Nuclear Information System (INIS)

    Graviele, M.S.; Miraglia, J.E.

    1988-01-01

    It is calculated the electronic capture of K shell by protons using the on-shell impulsive wave functions, exact and eikonal, in the initial and final channels respectively. Both wave functions are normalized and have the correct asyntotic conditions. A good agreement to the experimental data is found. (A.C.A.S.) [pt

  1. Measurement of Reactions on 30P for Nova Nucleosynthesis

    Science.gov (United States)

    Ma, Z.; Guidry, M. W.; Hix, W. R.; Smith, M. S.

    2003-05-01

    Replace these paragraphs with your abstract. We encourage you to include a sentence acknowledging your funding agency. In a recent study the 30P(p,gamma)31S rate played a crucial role in the synthesis of heavier nuclear species, from Si to Ca, in nova outbursts on ONe White Dwarfs [1]. The adopted rate of this reaction, based on a Hauser-Feshbach calculation [2], has a large uncertainty and could be as much as a factor of 100 too high or too low [3]. In their study, Jose et al.[1] varied the 30P(p,gamma)31S reaction rate within this uncertainty and found that, when rate is reduced by a factor of 100, the synthesis of elements above Si is lowered by a factor 10 with respect to the values found with the nominal rate. This has important consequences for nova nucleosynthesis, as overproduction of isotopes in the Si to Ca mass region has been observed in the ejecta from some nova explosions (e.g.,[4,5]). While generally valid at higher temperatures, Hauser-Feshbach calculations of the rates at nova temperatures can have large uncertainties. At these temperatures, the rate is more likely dominated by a few individual nuclear resonances. At present there are about 10 31S resonances known above the 30P + p threshold that may contribute to the 30P(p,gamma)31S reaction rate at nova temperatures. The excitation energies of these levels are known but spins and parities (for all but two) are not. We plan to measure the 30P(p,p)30P and 30P(p,gamma)31S reactions at HRIBF to better determine this reaction rate. A detailed description of the experiments will be given. We are also conducting a new nova nucleosynthesis simulation over multiple spatial zones of the exploding envelope to investigate the influence of the 30P(p,gamma)31S reaction rate on nova nucleosynthesis. The results of these calculations will be discussed. 1. Jose , J., Coc, A., Hernanz, M., Astrophys. J., 560, 897(2001). 2. Thielemann, F.-K et al., 1987, Advances in Nuclear Astrophysics, ed. E. Vangioni-Flam ( Gif

  2. Chaotic amplification of neutrino chemical potentials by neutrino oscillations in big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Shi, X.

    1996-01-01

    We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of big bang nucleosynthesis. We calculate the magnitude of the amplification and show evidence of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification in big bang nucleosynthesis. It is shown that with a ∼1 eV ν e , the amplification of its chemical potential by active-sterile neutrino oscillations can lower the effective number of neutrino species at big bang nucleosynthesis to significantly below three. copyright 1996 The American Physical Society

  3. Chaotic amplification of neutrino chemical potentials by neutrino oscillations in big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Shi, X. [Department of Physics, Queen`s University, Kingston, Ontario, K7L 3N6 (CANADA)

    1996-08-01

    We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of big bang nucleosynthesis. We calculate the magnitude of the amplification and show evidence of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification in big bang nucleosynthesis. It is shown that with a {approximately}1 eV {nu}{sub {ital e}}, the amplification of its chemical potential by active-sterile neutrino oscillations can lower the effective number of neutrino species at big bang nucleosynthesis to significantly below three. {copyright} {ital 1996 The American Physical Society.}

  4. Big bang nucleosynthesis with Gaussian inhomogeneous neutrino degeneracy

    International Nuclear Information System (INIS)

    Stirling, Spencer D.; Scherrer, Robert J.

    2002-01-01

    We consider the effect of inhomogeneous neutrino degeneracy on big bang nucleosynthesis for the case where the distribution of neutrino chemical potentials is given by a Gaussian. The chemical potential fluctuations are taken to be isocurvature, so that only inhomogeneities in the electron chemical potential are relevant. Then the final element abundances are a function only of the baryon-photon ratio η, the effective number of additional neutrinos ΔN ν , the mean electron neutrino degeneracy parameter ξ-bar, and the rms fluctuation of the degeneracy parameter, σ ξ . We find that for fixed η, ΔN ν , and ξ-bar, the abundances of 4 He, D, and 7 Li are, in general, increasing functions of σ ξ . Hence, the effect of adding a Gaussian distribution for the electron neutrino degeneracy parameter is to decrease the allowed range for η. We show that this result can be generalized to a wide variety of distributions for ξ

  5. Dark/visible parallel universes and Big Bang nucleosynthesis

    International Nuclear Information System (INIS)

    Bertulani, C. A.; Frederico, T.; Fuqua, J.; Hussein, M. S.; Oliveira, O.; Paula, W. de

    2012-01-01

    We develop a model for visible matter-dark matter interaction based on the exchange of a massive gray boson called herein the Mulato. Our model hinges on the assumption that all known particles in the visible matter have their counterparts in the dark matter. We postulate six families of particles five of which are dark. This leads to the unavoidable postulation of six parallel worlds, the visible one and five invisible worlds. A close study of big bang nucleosynthesis (BBN), baryon asymmetries, cosmic microwave background (CMB) bounds, galaxy dynamics, together with the Standard Model assumptions, help us to set a limit on the mass and width of the new gauge boson. Modification of the statistics underlying the kinetic energy distribution of particles during the BBN is also discussed. The changes in reaction rates during the BBN due to a departure from the Debye-Hueckel electron screening model is also investigated.

  6. Neutrino nucleosynthesis in core-collapse Supernova explosions

    Directory of Open Access Journals (Sweden)

    Sieverding A.

    2016-01-01

    Full Text Available The neutrino-induced nucleosynthesis (ν process in supernova explosions of massive stars of solar metallicity with initial main sequence masses between 15 and 40 M⊙ has been studied. A new extensive set of neutrino-nucleus cross-sections for all the nuclei included in the reaction network is used and the average neutrino energies are reduced to agree with modern supernova simulations. Despite these changes the ν process is found to contribute still significantly to the production of the nuclei 7Li, 11B, 19F, 138La and 180Ta, even though the total yields for those nuclei are reduced. Furthermore we study in detail contributions of the ν process to the production of radioactive isotopes 26Al, 22Na and confirm the production of 92Nb and 98Tc.

  7. Light element nucleosynthesis and estimates of the universal baryon density

    International Nuclear Information System (INIS)

    Mathews, G.J.; Viola, V.E.

    1978-01-01

    The present mean universal baryon density rho/sub b/, is of interest because it and the Hubble constant determine the curvature of the Universe. The available indicators of rho/sub b/ come from the present deuterium abundance, if it is assumed that ''big-bang'' nucleosynthesis must produce enough D to at least match the abundance of this nuclide in the interstellar medium. An alternative method utilizing the 7 Li/D ratio is used to evaluate rho/sub b/. With this method the difficulty associated with the astration process can be essentially canceled from the problem. The results obtained indicate an open Universe with a best guess for rho/sub b/ of 7.1 x 10 -31 g/cm 3 . 1 figure, 1 table

  8. Big Bang nucleosynthesis and the quark-hadron transition

    International Nuclear Information System (INIS)

    Kurki-suonio, H.; Matzner, R.A.; Olive, K.A.; Schramm, D.N.

    1989-12-01

    An examination and brief review is made of the effects of quark-hadron transistion induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R much greater than 10(exp 3), whereas the simplest models for the transition seem to restrict R to less than approximately 10(exp 2)

  9. Big Bang nucleosynthesis and abundances of light elements

    International Nuclear Information System (INIS)

    Pagel, B.E.J.

    1991-01-01

    Big Bang nucleosynthesis (BBNS) theory is sketched, indicating the dependence of primordial abundances of D, 3 He, 4 He and 7 Li on the mean baryonic density of the universe and the dependence of 4 He on the number of neutrino families and the neutron half-life. Observational data and inferred primordial abundances of these elements are reviewed and shown to be consistent (within errors) either with standard BBNS in a homogeneous universe about 100 seconds after the Big Bang or with moderately inhomogeneous BBNS models resulting from earlier phase transitions like the quark-hadron transition if this is first order. However, models with closure density supplied by baryons are apparently ruled out. Finally, implications for the existence of baryonic and non-baryonic dark matter are briefly discussed. (orig.)

  10. Big bang nucleosynthesis and the quark-hadron transition

    Science.gov (United States)

    Kurki-Suonio, Hannu; Matzner, Richard A.; Olive, Keith A.; Schramm, David N.

    1990-01-01

    An examination and brief review is made of the effects of quark-hadron transition induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R is much greater the 10(exp e), whereas the simplest models for the transition seem to restrict R to less than of approximately 10(exp 2).

  11. Massive stars with mass loss: Evolution, nucleosynthesis, and astrophysical implications

    International Nuclear Information System (INIS)

    Prantzos, N.

    1986-06-01

    Evolution and nucleosynthesis of mass loss WR stars is studied, particularly evolution of stars with initial mass between 50 and 100 solar masses, during combustion of H and He. A semi-empirical mass loss formalism, the Roxburgh criterion for convection, and nuclear data are used. Composition of the stellar surface and ejecta (and ejecta contribution to cosmic ray composition) are derived. The contribution of these stars to s elements in our solar system is shown. Their production of 26 Al is compared to the quantity in the galaxy. Gamma ray emission at 1.8 MeV from the decay of this radionuclide is estimated in galactic longitude. The stars evolve as 0 and 0f stars during H combustion and spend 20% of their He combustion period as WN stars and 80% as WC-W0. Evolution always occurs in the blue part of the HR diagram, and satisfies observational constraints on its upper part [fr

  12. Gravitino, dark matter candidate and implications for big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Bailly, S.

    2008-11-01

    The Standard Model of particle physics was developed in the seventies. Despite many experimental successes, it presents many problems that can only be solved with models beyond the Standard Model. Supersymmetry is an interesting candidate, postulating a new symmetry between fermions and bosons. This model can also have interesting applications in cosmology. It offers potentially good candidates for dark matter, what represents 25% of the energy density of the Universe, and its nature is unknown. Another cosmological problem is the lithium problems in Big Bang Nucleosynthesis describing the production of light elements in the first seconds of the Universe. The lithium abundance predicted by the theory is inconsistent with observations. I study a scenario in which a supersymmetric particle, the gravitino, is the candidate for dark matter and the production of this particle through the decay of other supersymmetric particles may solve the lithium problems. (author)

  13. Quark mass variation constraints from Big Bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bedaque, P; Luu, T; Platter, L

    2010-12-13

    We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way we use lattice QCD data and an hierarchy of effective field theories. We find that the measured {sup 4}He abundances put a bound of {delta}-1% {approx}< m{sub q}/m{sub 1} {approx}< 0.7%. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio {eta}. Including the bounds on the variation of {eta} coming from WMAP results and some additional assumptions narrows the range of allowed values of {delta}m{sub q}/m{sub q} somewhat.

  14. Neutrino nucleosynthesis in core-collapse Supernova explosions

    Science.gov (United States)

    Sieverding, A.; Huther, L.; Martínez-Pinedo, G.; Langanke, K.; Heger, A.

    2018-01-01

    The neutrino-induced nucleosynthesis (v process) in supernova explosions of massive stars of solar metallicity with initial main sequence masses between 15 and 40 M⨀ has been studied. A new extensive set of neutrino-nucleus cross-sections for all the nuclei included in the reaction network is used and the average neutrino energies are reduced to agree with modern supernova simulations. Despite these changes the v process is found to contribute still significantly to the production of the nuclei 7Li, 11B, 19F, 138La and 180Ta, even though the total yields for those nuclei are reduced. Furthermore we study in detail contributions of the v process to the production of radioactive isotopes 26Al, 22Na and confirm the production of 92Nb and 98Tc.

  15. Computational Astrophysics Consortium 3 - Supernovae, Gamma-Ray Bursts and Nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, Stan [Univ. of California, Santa Cruz, CA (United States)

    2014-08-29

    Final project report for UCSC's participation in the Computational Astrophysics Consortium - Supernovae, Gamma-Ray Bursts and Nucleosynthesis. As an appendix, the report of the entire Consortium is also appended.

  16. Cosmological nucleosynthesis and active-sterile neutrino oscillations with small mass differences: the nonresonant case

    International Nuclear Information System (INIS)

    Kirilova, D.P.; Chizhov, M.V.

    1998-05-01

    We study the nonresonant oscillations between left-handed electron neutrinos ν s and nonthermalized sterile neutrinos ν s in the early Universe plasma. The case when ν s do not thermalize till 2 MeV and the oscillations become effective after ν e decoupling is discussed. As far as for this model the rates of expansion of the Universe, neutrino oscillations and neutrino interactions with the medium may be comparable, we have analyzed the kinetic equations for neutrino density matrix, accounting simultaneously for these processes. The evolution of neutrino ensembles was described numerically by integrating the kinetic equations for the neutrino density matrix in momentum space for small mass differences δm 2 ≤10 -7 eV 2 . This approach allowed us to study precisely the evolution of the neutrino number densities, energy spectrum distortion and the asymmetry between neutrinos and antineutrinos due to oscillations for each momentum mode. We have performed a complete numerical analysis for the full range of the oscillations parameters of the model of the influence of the nonequilibrium ν e ↔ν s oscillations on the primordial production of 4 He. The exact kinetic approach enabled us to calculate the effects of neutrino population depletion, the distortion of the neutrino spectrum and the generation of neutrino-antineutrino asymmetry on the kinetics of neutron-to-proton transitions during the primordial nucleosynthesis epoch and correspondingly on the cosmological 4 He production. It was shown that the neutrino population depletion and spectrum distortion play an important role. The asymmetry effect, in case the lepton asymmetry is accepted initially equal to the baryon one, is proved to be negligible for the discussed range of δm 2 . Constant helium contours in δm 2 -θ plane were calculated. Thanks to the exact kinetic approach more precise cosmological constraints on the mixing parameters were obtained. (author)

  17. Primordial nucleosynthesis in inhomogeneous cosmologies: Ω = 1 with baryonic dark matter

    International Nuclear Information System (INIS)

    Mathews, G.J.; Sale, K.E.

    1986-09-01

    We consider the constraints on Ω from primordial nucleosynthesis in inhomogeneous cosmologies. We find that allowance for isothermal fluctuations significantly weakens the upper bound on the average value of Ω derived from the standard big bang. Under the plausible additional assumption that regions of high baryon density are preferentially absorbed into cold dark matter, the constraints from primordial nucleosynthesis can be satisfied for large values of Ω, including Ω = 1. 22 refs., 2 figs

  18. Microscopic study of proton emission from heavy nuclei

    International Nuclear Information System (INIS)

    Sahu, B.B.; Patra, S.K.; Agarwalla, S.K.

    2011-01-01

    In recent years many theoretical calculations have been employed to explain the observed lifetimes of proton radioactivity and alpha decay processes in the region of proton rich nuclei. These data are very promising for the analysis of possible irregularities in the structure of these proton-rich nuclei. They are also of great interest in rapid proton capture processes. Some new results for proton radioactivity in this region of proton-rich nuclei have indicated that the proton emission mode is rather competitive with the alpha decay one. In the energy domain of radioactivity, proton can be considered as a point charge having highest probability of being present in the parent nucleus

  19. r-Process nucleosynthesis from three-dimensional jet-driven core-collapse supernovae with magnetic misalignments

    Science.gov (United States)

    Halevi, Goni; Mösta, Philipp

    2018-06-01

    We investigate r-process nucleosynthesis in three-dimensional general relativistic magnetohydrodynamic simulations of jet-driven supernovae resulting from rapidly rotating, strongly magnetized core-collapse. We explore the effect of misaligning the pre-collapse magnetic field with respect to the rotation axis by performing four simulations: one aligned model and models with 15°, 30°, and 45° misalignments. The simulations we present employ a microphysical finite-temperature equation of state and a leakage scheme that captures the overall energetics and lepton number exchange due to post-bounce neutrino emission and absorption. We track the thermodynamic properties of the ejected material with Lagrangian tracer particles and analyse its composition with the nuclear reaction network SKYNET. By using different neutrino luminosities in post-processing the tracer data with SKYNET, we constrain the impact of uncertainties in neutrino luminosities. We find that, for the aligned model considered here, the use of an approximate leakage scheme results in neutrino luminosity uncertainties corresponding to a factor of 100-1000 uncertainty in the abundance of third peak r-process elements. Our results show that for misalignments of 30° or less, r-process elements are robustly produced as long as neutrino luminosities are reasonably low (≲ 5 × 1052 erg s-1). For a more extreme misalignment of 45°, we find the production of r-process elements beyond the second peak significantly reduced. We conclude that robust r-process nucleosynthesis in magnetorotational supernovae requires a progenitor stellar core with a large poloidal magnetic field component that is at least moderately (within ˜30°) aligned with the rotation axis.

  20. The Revival of Galactic Cosmic-Ray Nucleosynthesis?

    International Nuclear Information System (INIS)

    Fields, B.D.; Olive, K.A.

    1999-01-01

    Because of the roughly linear correlation between Be/H and Fe/H in low-metallicity halo stars, it has been argued that a open-quotes primaryclose quotes component in the nucleosynthesis of Be must be present in addition to the open-quotes secondaryclose quotes component from standard Galactic cosmic-ray nucleosynthesis. In this paper we critically reevaluate the evidence for the primary versus secondary character of Li, Be, and B (LiBeB) evolution, analyzing both the observations and Galactic chemical evolution models. Although it appears that [Be/H] versus [Fe/H] has a logarithmic slope near 1, it is rather the Be-O trend that directly arises from the physics of spallation production. Using new abundances for oxygen in halo stars based on UV OH lines, we find that in Population II stars for which O has been measured, the Be-O slope has a large uncertainty due to systematic effects. Namely, the Be-O logarithmic slope lies in the range 1.3 endash 1.8, rendering it difficult to distinguish from the data between the secondary slope of 2 and the primary slope of 1. The possible difference between the Be-Fe and Be-O slopes is a consequence of the variation in O/Fe versus Fe: recent data suggest that the best-fit O/Fe-Fe slope for Population II is in the range -0.5 to -0.2, rather than zero (i.e., Fe∝O) as is often assumed. In addition to this phenomenological analysis of Be and B evolution, we have also examined the predicted LiBeB, O, and Fe trends in Galactic chemical evolution models that include outflow. Based on our results, it is possible that a good fit to the LiBeB evolution requires only the traditional Galactic cosmic-ray spallation and the (primary) neutrino-process contribution to 11 B. We thus suggest that these two processes might be sufficient to explain 6 Li, Be, and B evolution in the Galaxy, without the need for an additional primary source of Be and B. However, the uncertainties in the data at this time prevent one from reaching a definitive

  1. Proton therapy

    International Nuclear Information System (INIS)

    Smith, Alfred R

    2006-01-01

    Proton therapy has become a subject of considerable interest in the radiation oncology community and it is expected that there will be a substantial growth in proton treatment facilities during the next decade. I was asked to write a historical review of proton therapy based on my personal experiences, which have all occurred in the United States, so therefore I have a somewhat parochial point of view. Space requirements did not permit me to mention all of the existing proton therapy facilities or the names of all of those who have contributed to proton therapy. (review)

  2. Mass spectrometry of stardust : experimental tests of nucleosynthesis

    International Nuclear Information System (INIS)

    Clayton, R.N.

    1997-01-01

    Primitive meteorites contain grains of diamond, graphite and silicon carbide which condensed from the outflows of red-giant stars, which existed before the formation of our Sun and Solar System. Nuclear processes within the parent star have modified the isotopic compositions of all elements in the grains. By means of a very sensitive and selective microanalytical technique, Resonant Ionization Mass Spectrometry, we can measure isotopic abundances of trace metals in individual 3-micrometer-sized crystals. The technique uses multi-photon photoionization with tuned lasers to ionize a single element selectively and efficiently. This allows isotopic measurements of trace constituents in complex systems. Results from zirconium and molybdenum in presolar silicon carbide grains show large enhancements in the s-process isotopes, and depletion by factors >2 in the r-process and p-process isotopes. The observations are in good agreement with recent calculations of s-process nucleosynthesis in Asymptotic Giant Branch stars. These results confirm the classical subdivision of nucleo-synthetic processes into p-, r-, and s-processes and show that the principal site of the s-process is in carbon-rich red giant stars. (author)

  3. Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons

    International Nuclear Information System (INIS)

    Schelke, M.; Catena, R.; Fornengo, N.; Masiero, A.; Pietroni, M.

    2006-06-01

    A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble-rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50-500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of non-standard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model. (Orig.)

  4. Chaos and turbulent nucleosynthesis prior to a supernova explosion

    Directory of Open Access Journals (Sweden)

    W. D. Arnett

    2014-03-01

    Full Text Available Three-dimensional (3D, time dependent numerical simulations of flow of matter in stars, now have sufficient resolution to be fully turbulent. The late stages of the evolution of massive stars, leading up to core collapse to a neutron star (or black hole, and often to supernova explosion and nucleosynthesis, are strongly convective because of vigorous neutrino cooling and nuclear heating. Unlike models based on current stellar evolutionary practice, these simulations show a chaotic dynamics characteristic of highly turbulent flow. Theoretical analysis of this flow, both in the Reynolds-averaged Navier-Stokes (RANS framework and by simple dynamic models, show an encouraging consistency with the numerical results. It may now be possible to develop physically realistic and robust procedures for convection and mixing which (unlike 3D numerical simulation may be applied throughout the long life times of stars. In addition, a new picture of the presupernova stages is emerging which is more dynamic and interesting (i.e., predictive of new and newly observed phenomena than our previous one.

  5. Big Bang Nucleosynthesis and Cosmological Constraints on Neutrino Oscillation Parameters

    CERN Document Server

    Kirilova, Daniela P; Kirilova, Daniela; Chizhov, Mihail

    2001-01-01

    We present a review of cosmological nucleosynthesis (CN) with neutrino oscillations, discussing the different effects of oscillations on CN, namely: increase of the effective degrees of freedom during CN, spectrum distortion of the oscillating neutrinos, neutrino number density depletion, and growth of neutrino-antineutrino asymmetry due to active-sterile oscillations. We discuss the importance of these effects for the primordial yield of helium-4. Primordially produced He-4 value is obtained in a selfconsistent study of the nucleons and the oscillating neutrinos. The effects of spectrum distortion, depletion and neutrino-antineutrino asymmetry growth on helium-4 production are explicitly calculated. An update of the cosmological constraints on active-sterile neutrino oscillations parameters is presented, giving the values: delta m^2 sin^8 (2 theta) 0, and |delta m^2| < 8.2 x 10^{-10} eV^2 at large mixing angles for delta m^2 < 0. According to these constraints, besides the active-sterile LMA solution,...

  6. Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Schelke, M. [Istituto Nazionale di Fisica Nucleare, Torino (Italy); Catena, R. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Fornengo, N. [Torino Univ. (Italy). Dipt. di Fisica Teorica]|[Istituto Nazionale di Fisica Nucleare, Torino (Italy); Masiero, A. [Pavoa Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padova (Italy); Pietroni, M. [Istituto Nazionale di Fisica Nucleare, Padova (Italy)

    2006-06-15

    A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble-rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50-500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of non-standard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model. (Orig.)

  7. r-process nucleosynthesis in dynamic helium-burning environments

    Science.gov (United States)

    Cowan, J. J.; Cameron, A. G. W.; Truran, J. W.

    1985-01-01

    The results of an extended examination of r-process nucleosynthesis in helium-burning enviroments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the C-13 neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be 10 to the 20th-10 to the 21st neutrons per cubic centimeter for times of 0.01-0.1 s and neutron number densities in excess of 10 to the 19th per cubic centimeter for times of about 1 s. The amount of C-13 required is found to be exceedingly high - larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system.

  8. Observational constraints on secret neutrino interactions from big bang nucleosynthesis

    Science.gov (United States)

    Huang, Guo-yuan; Ohlsson, Tommy; Zhou, Shun

    2018-04-01

    We investigate possible interactions between neutrinos and massive scalar bosons via gϕν ¯ν ϕ (or massive vector bosons via gVν ¯γμν Vμ) and explore the allowed parameter space of the coupling constant gϕ (or gV) and the scalar (or vector) boson mass mϕ (or mV) by requiring that these secret neutrino interactions (SNIs) should not spoil the success of big bang nucleosynthesis (BBN). Incorporating the SNIs into the evolution of the early Universe in the BBN era, we numerically solve the Boltzmann equations and compare the predictions for the abundances of light elements with observations. It turns out that the constraint on gϕ and mϕ in the scalar-boson case is rather weak, due to a small number of degrees of freedom (d.o.f.). However, in the vector-boson case, the most stringent bound on the coupling gV≲6 ×10-10 at 95% confidence level is obtained for mV≃1 MeV , while the bound becomes much weaker gV≲8 ×10-6 for smaller masses mV≲10-4 MeV . Moreover, we discuss in some detail how the SNIs affect the cosmological evolution and the abundances of the lightest elements.

  9. Big bang nucleosynthesis: The standard model and alternatives

    Science.gov (United States)

    Schramm, David N.

    1991-01-01

    Big bang nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the big bang cosmological model. This paper reviews the standard homogeneous-isotropic calculation and shows how it fits the light element abundances ranging from He-4 at 24% by mass through H-2 and He-3 at parts in 10(exp 5) down to Li-7 at parts in 10(exp 10). Furthermore, the recent large electron positron (LEP) (and the stanford linear collider (SLC)) results on the number of neutrinos are discussed as a positive laboratory test of the standard scenario. Discussion is presented on the improved observational data as well as the improved neutron lifetime data. Alternate scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conlusions on the baryonic density relative to the critical density, omega(sub b) remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the conclusion that omega(sub b) approximately equals 0.06. This latter point is the driving force behind the need for non-baryonic dark matter (assuming omega(sub total) = 1) and the need for dark baryonic matter, since omega(sub visible) is less than omega(sub b).

  10. Supernova nucleosynthesis and the physics of neutrino oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Kajino, Toshitaka [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan) and Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2012-11-20

    We studied the explosive nucleosynthesis in core-collapse supernovae and found that several isotopes of rare elements like {sup 7}Li, {sup 11}B, {sup 138}La, {sup 180}Ta and others are predominantly produced by the neutrino interactions with several abundant nuclei. These isotopes are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect. We here first study how to know the suitable average neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the neutrino oscillation parameters, {theta}{sub 13} and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process {sup 11}B and {sup 7}Li encapsulated in the grains. Combining the recent experimental constraints on {theta}{sub 13}, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

  11. Supernova nucleosynthesis and the physics of neutrino oscillation

    Science.gov (United States)

    Kajino, Toshitaka

    2012-11-01

    We studied the explosive nucleosynthesis in core-collapse supernovae and found that several isotopes of rare elements like 7Li, 11B, 138La, 180Ta and others are predominantly produced by the neutrino interactions with several abundant nuclei. These isotopes are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect. We here first study how to know the suitable average neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

  12. Big bang nucleosynthesis: The standard model and alternatives

    International Nuclear Information System (INIS)

    Schramm, D.N.

    1991-01-01

    Big bang nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the big bang cosmological model. This paper reviews the standard homogeneous-isotropic calculation and shows how it fits the light element abundances ranging from 4 He at 24% by mass through 2 H and 3 He at parts in 10 5 down to 7 Li at parts in 10 10 . Furthermore, the recent LEP (and SLC) results on the number of neutrinos are discussed as a positive laboratory test of the standard scenario. Discussion is presented on the improved observational data as well as the improved neutron lifetime data. Alternate scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conclusions on the baryonic density relative to the critical density, Ω b , remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the conclusion that Ω b ≅0.06. This latter point is the driving force behind the need for non-baryonic dark matter (assuming Ω total =1) and the need for dark baryonic matter, since Ω visible b . (orig.)

  13. The exact parity symmetric model and big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Foot, R.; Volkas, R.R.

    1996-12-01

    The assumption of exact, unbroken parity symmetry leads directly to a simple predictive resolution of the atmospheric and solar neutrino puzzles. This is because the existence of this symmetry implies the existence of a set of mirror neutrinos which must mix maximally with the known neutrinos if neutrinos have mass. the maximal mixing of the electron neutrino with the mirror electron neutrino with 3 x 10{sup -10} eV{sup 2} {<=} |{delta}m{sup 2}| {<=} 10{sup -3} eV{sup 2} leads to a predicted reduction of the solar neutrino flux by-a factor of 2, which is in quite good agreement with the experiments. The maximal mixing of the muon neutrino with the mirror muon neutrino with |{delta}m{sup 2}| {approx} 10{sup -2} eV{sup 2} also solves the atmospheric neutrino puzzle. We show that there is a significant range of parameters where these solutions are not in conflict with standard Big Bang Nucleosynthesis when the creation of lepton asymmetry due to neutrino oscillations is taken into account. (authors).

  14. r-process nucleosynthesis in dynamic helium-burning environments

    International Nuclear Information System (INIS)

    Cowan, J.J.; Cameron, A.G.W.; Truran, J.W.

    1985-01-01

    The results of an extended examination of r-process nucleosynthesis in helium-burning environments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the 13 C neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be: 10 20 --10 21 neutrons cm -3 for times of 0.01--0.1 s and neutron number densities in excess of 10 19 cm -3 for times of approx.1 s. The amount of 13 C required is found to be exceedingly high: larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system

  15. Explosive nucleosynthesis in a neutrino-driven core collapse supernova

    International Nuclear Information System (INIS)

    Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

    2010-01-01

    We investigate explosive nucleosynthesis in a delayed neutrino-driven, supernova explosion aided by standing accretion shock instability (SASI), based on two-dimensional hydrodynamic simulations of the explosion of a 15 M · star. We take into accounts neutrino heating and cooling as well as change in electron fraction due to weak interactions appropriately, in the two-dimensional simulations. We assume the isotropic emission of neutrinos from the neutrino spheres with given luminosities. and the Fermi-Dirac distribution of given temperatures. We find that the stalled shock revives due to the neutrino heating aided by SASI for cases with L νe ≥3.9x10 52 ergss -1 and the as-pherical shock passes through the outer layers of the star (≥10,000 km), with the explosion energies of ∼10 51 ergs.Next we examine abundances and masses of the supernova ejecta. We find that masses of the ejecta and 56 Ni correlate with the neutrino luminosity, and 56 Ni mass is comparable to that observed in SN 1987A. We also find that abundance pattern of the supernova ejecta is similar to that of the solar system, for cases with high explosion energies of >10 51 ergs. We emphasize that 64 Zn, which is underproduced in the spherical case, is abundantly produced in slightly neutron-rich ejecta.

  16. Resonance parameters for measured keV neutron capture cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Musgrove, A.R. de L

    1969-05-01

    All available neutron capture cross sections in the keV region ({approx} to 100 keV) have been fitted with resonance parameters. Capture cross sections for nuclides with reasonably well known average s-wave parameters, but no measured cross section, have been calculated and tabulated using p-and d- wave strength functions interpolated between fitted values. Several of these nuclides are of interest in the theory of slow nucleosynthesis of heavy elements in stars, and the product of cosmic abundance (due to the s-process) and capture cross section at 30 keV has been plotted versus mass number. (author)

  17. Neutrinos, Weak Interactions, and r-process Nucleosynthesis

    International Nuclear Information System (INIS)

    Balantekin, A B

    2006-01-01

    Two of the key issues in understanding the neutron-to-proton ratio in a corecollapse supernova are discussed. One of these is the behavior of the neutrino-nucleon cross sections as supernova energies. The other issue is the many-body properties of the neutrino gas near the core when both one- and two-body interaction terms are included

  18. The nTOF Total Absorption Calorimeter for neutron capture measurements at CERN

    International Nuclear Information System (INIS)

    Guerrero, C.; Abbondanno, U.; Aerts, G.; Alvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapico, C.; Cennini, P.; Chepel, V.

    2009-01-01

    The n T OF Collaboration has built and commissioned a high-performance detector for (n,γ) measurements called the Total Absorption Calorimeter (TAC). The TAC was especially designed for measuring neutron capture cross-sections of low-mass and/or radioactive samples with the accuracy required for nuclear technology and stellar nucleosynthesis. We present a detailed description of the TAC and discuss its overall performance in terms of energy and time resolution, background discrimination, detection efficiency and neutron sensitivity.

  19. Astrophysical S-factor of the 32He(α,γ) 733 7Be reaction in the Big-Bang nucleosynthesis

    Science.gov (United States)

    Ghamary, Motahareh; Sadeghi, Hossein; Mohammadi, Saeed

    2018-05-01

    In the present work, we have studied the properties of the 23He(α , γ) 47Be reaction. The direct radiative capture nuclear reactions in the Big-Bang nucleosynthesis mainly, are done in the external areas of inter-nuclear interaction range and play an essential role in nuclear astrophysics. Among of these reactions, the 23He(α , γ) 47Be reaction with Q = 1.586 MeV is the main part of the Big-Bang nucleosynthesis chain reactions. This reaction can be used to understand the physical and chemical properties of the sun as well as can be justified the lake of the observed solar neutrino in the detector of the Earth. Since product neutrino fluxes are predicated in the center of the sun by the decay of 7Be and 8B, and almost are proportional to the astrophysical S-factor for the 23He(α , γ) 47Be reaction, S34. The 23He(α , γ) 47Be reaction is considered the key to solve the solar neutrino puzzle. Finally, we have astrophysical S-factor obtained for the ground S1,3/2-, first excited S1,1/2-and total S34 states by modern nucleon-nucleon two-body local potential models. We have also compared the obtained S-factor with experimental data and other theoretical works.

  20. THE {sup 12}C + {sup 12}C REACTION AND THE IMPACT ON NUCLEOSYNTHESIS IN MASSIVE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Pignatari, M. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Hirschi, R.; Bennett, M. [Astrophysics Group, EPSAM Institute, Keele University, Keele, ST5 5BG (United Kingdom); Wiescher, M.; Beard, M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Gallino, R. [Universita' di Torino, Torino, Via Pietro Giuria 1, I-10126 Torino (Italy); Fryer, C.; Rockefeller, G. [Computational Physics and Methods (CCS-2), LANL, Los Alamos, NM 87545 (United States); Herwig, F.; Timmes, F. X., E-mail: marco.pignatari@unibas.ch [The Joint Institute for Nuclear Astrophysics, Notre Dame, IN 46556 (United States)

    2013-01-01

    Despite much effort in the past decades, the C-burning reaction rate is uncertain by several orders of magnitude, and the relative strength between the different channels {sup 12}C({sup 12}C, {alpha}){sup 20}Ne, {sup 12}C({sup 12}C, p){sup 23}Na, and {sup 12}C({sup 12}C, n){sup 23}Mg is poorly determined. Additionally, in C-burning conditions a high {sup 12}C+{sup 12}C rate may lead to lower central C-burning temperatures and to {sup 13}C({alpha}, n){sup 16}O emerging as a more dominant neutron source than {sup 22}Ne({alpha}, n){sup 25}Mg, increasing significantly the s-process production. This is due to the chain {sup 12}C(p, {gamma}){sup 13}N followed by {sup 13}N({beta} +){sup 13}C, where the photodisintegration reverse channel {sup 13}N({gamma}, p){sup 12}C is strongly decreasing with increasing temperature. Presented here is the impact of the {sup 12}C+{sup 12}C reaction uncertainties on the s-process and on explosive p-process nucleosynthesis in massive stars, including also fast rotating massive stars at low metallicity. Using various {sup 12}C+{sup 12}C rates, in particular an upper and lower rate limit of {approx}50,000 higher and {approx}20 lower than the standard rate at 5 Multiplication-Sign 10{sup 8} K, five 25 M {sub Sun} stellar models are calculated. The enhanced s-process signature due to {sup 13}C({alpha}, n){sup 16}O activation is considered, taking into account the impact of the uncertainty of all three C-burning reaction branches. Consequently, we show that the p-process abundances have an average production factor increased up to about a factor of eight compared with the standard case, efficiently producing the elusive Mo and Ru proton-rich isotopes. We also show that an s-process being driven by {sup 13}C({alpha}, n){sup 16}O is a secondary process, even though the abundance of {sup 13}C does not depend on the initial metal content. Finally, implications for the Sr-peak elements inventory in the solar system and at low metallicity are

  1. Big bang nucleosynthesis with a varying fine structure constant and nonstandard expansion rate

    International Nuclear Information System (INIS)

    Ichikawa, Kazuhide; Kawasaki, Masahiro

    2004-01-01

    We calculate the primordial abundances of light elements produced during big bang nucleosynthesis when the fine structure constant and/or the cosmic expansion rate take nonstandard values. We compare them with the recent values of observed D, 4 He, and 7 Li abundances, which show a slight inconsistency among themselves in the standard big bang nucleosynthesis scenario. This inconsistency is not solved by considering either a varying fine structure constant or a nonstandard expansion rate separately but solutions are found by their simultaneous existence

  2. Laboratory approaches of nuclear reactions involved in primordial and stellar nucleosynthesis

    International Nuclear Information System (INIS)

    Rolfs, C.; California Inst. of Tech., Pasadena

    1986-01-01

    Laboratory-based studies of primordial and stellar nucleosynthesis are reviewed, with emphasis on the nuclear reactions induced by charged particles. The analytical approach used to investigate nuclear reactions associated with stellar reactions is described, as well as the experimental details and procedures used to investigate nuclear reactions induced by charged particles. The present knowledge of some of the key reactions involved in primordial nucleosynthesis is discussed, along with the progress and problems of nuclear reactions involved in the hydrogen and helium burning phases of a star. Finally, a description is given of new experimental techniques which might be useful for future experiments in the field of nuclear astrophysics. (U.K.)

  3. Constraining neutrino physics with big bang nucleosynthesis and cosmic microwave background radiation

    International Nuclear Information System (INIS)

    Hansen, S.H.; Melchiorri, A.; Mangano, G.; Miele, G.; Pisanti, O.

    2002-01-01

    We perform a likelihood analysis of the recent results on the anisotropy of cosmic microwave background radiation from the BOOMERanG and DASI experiments to show that they single out an effective number of neutrinos in good agreement with standard big bang nucleosynthesis. We also consider degenerate big bang nucleosynthesis to provide new bounds on effective relativistic degrees of freedom N ν and, in particular, on the neutrino chemical potential ξ α . When including supernova type Ia data we find, at 2σ, N ν ≤7 and -0.01≤ξ e ≤0.22, vertical bar ξ μ,τ vertical bar ≤2.6

  4. Constraining antimatter domains in the early universe with big bang nucleosynthesis.

    Science.gov (United States)

    Kurki-Suonio, H; Sihvola, E

    2000-04-24

    We consider the effect of a small-scale matter-antimatter domain structure on big bang nucleosynthesis and place upper limits on the amount of antimatter in the early universe. For small domains, which annihilate before nucleosynthesis, this limit comes from underproduction of 4He. For larger domains, the limit comes from 3He overproduction. Since most of the 3He from &pmacr; 4He annihilation are themselves annihilated, the main source of primordial 3He is the photodisintegration of 4He by the electromagnetic cascades initiated by the annihilation.

  5. Radiative capture of nucleons at astrophysical energies with single-particle states

    International Nuclear Information System (INIS)

    Huang, J.T.; Bertulani, C.A.; Guimaraes, V.

    2010-01-01

    Radiative capture of nucleons at energies of astrophysical interest is one of the most important processes for nucleosynthesis. The nucleon capture can occur either by a compound nucleus reaction or by a direct process. The compound reaction cross sections are usually very small, especially for light nuclei. The direct capture proceeds either via the formation of a single-particle resonance or a non-resonant capture process. In this work we calculate radiative capture cross sections and astrophysical S-factors for nuclei in the mass region A<20 using single-particle states. We carefully discuss the parameter fitting procedure adopted in the simplified two-body treatment of the capture process. Then we produce a detailed list of cases for which the model works well. Useful quantities, such as spectroscopic factors and asymptotic normalization coefficients, are obtained and compared to published data.

  6. Nucleosynthesis in Wolf-Rayet stars and galactic cosmic-ray isotopic composition

    International Nuclear Information System (INIS)

    Prantzos, N.

    1984-01-01

    An explanation of the isotopic composition of galactic cosmic rays could provide some clues to the mystery of their origin. It seems now that the strong stellar winds of Wolf-Rayet stars could account for most of the isotopic anomalies that have been observed in cosmic rays. Some results are presented, obtained by detailed nucleosynthesis computations. 25 references

  7. Abundances of La and Ta Through ν-Nucleosynthesis in 20M ...

    Indian Academy of Sciences (India)

    Solar mass fractions of the seeds La139, Ta181, Ba138 and Hf180 are taken for calculation. They are assumed to be produced in ... of these elements by extending the earlier works on neutrino nucleosynthesis in massive stars. .... ing the shock heating of the layers surrounding the collapsing core of supernova progenitor.

  8. Neutron capture reactions on Lu isotopes at DANCE

    CERN Document Server

    Roig, O

    2010-01-01

    The DANCE (Detector for Advanced Neutron Capture Experiments) array located at the Los Alamos national laboratory has been used to obtain the neutron capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process in astrophysics and for applications as in reactor physics or in nuclear medicine. Three targets were used to perform these measurements. One was natLu foil and the other two were isotope-enriched targets of 175Lu and 176Lu. The cross sections are obtained for now through a precise neutron flux determination and a normalization at the thermal neutron cross section value. A comparison with the recent experimental data and the evaluated data of ENDF/B-VII.0 will be presented. In addition, resonances parameters and spin assignments for some resonances will be featured.

  9. Virtual-bremsstrahlung production in proton-proton scattering and proton-deuteron capture

    NARCIS (Netherlands)

    Messchendorp, Johannes Gerhardus

    1999-01-01

    The well-known coupling of the photon with the nucleon together with the fact that photons (or any electromagnetic (e.m.) probe) interact only relatively weakly with nucleons, make bremsstrahlung production an ideal tool to study details of the nucleon-nucleon interaction. In this thesis dilepton

  10. Proton decay theory

    International Nuclear Information System (INIS)

    Marciano, W.J.

    1983-01-01

    Topics include minimal SU(5) predictions, gauge boson mediated proton decay, uncertainties in tau/sub p/, Higgs scalar effects, proton decay via Higgs scalars, supersymmetric SU(5), dimension 5 operators and proton decay, and Higgs scalars and proton decay

  11. Proton therapy

    International Nuclear Information System (INIS)

    Jongen, Y.

    1995-01-01

    Ideal radiotherapy deposits a large amount of energy in the tumour volume, and none in the surrounding healthy tissues. Proton therapy comes closer to this goal because of a greater concentration of dose, well defined proton ranges and points of energy release which are precisely known - the Bragg peak1. In the past, the development of clinical proton therapy has been hampered by complexity, size, and cost. To be clinically effective, energies of several hundred MeV are required; these were previously unavailable for hospital installations, and pioneering institutions had to work with complex, inadequate equipment originally intended for nuclear physics research. Recently a number of specialist organizations and commercial companies have been working on dedicated systems for proton therapy. One, IBA of Belgium, has equipment for inhouse hospital operation which encompasses a complete therapy centre, delivered as a turnkey package and incorporating a compact, automated, higher energy cyclotron with isocentric gantries. Their system will be installed at Massachusetts General Hospital, Boston. The proton therapy system comprises: - a 235 MeV isochronous cyclotron to deliver beams of up to 1.5 microamps, but with a hardware limitation to restrict the maximum possible dose; - variable energy beam (235 to 70 MeV ) with energy spread and emittance verification; - a beam transport and switching system to connect the exit of the energy selection system to the entrances of a number of gantries and fixed beamlines. Along the beam transport system, the beam characteristics are monitored with non-interceptive multiwire ionization chambers for automatic tuning; - gantries fitted with nozzles and beamline elements for beam control; both beam scattering and beam wobbling techniques are available for shaping the beam;

  12. Radiative nucleon capture with quasi-separable potentials

    International Nuclear Information System (INIS)

    Shubhchintak; Bertulani, C A; Mukhamedzhanov, A M; Kruppa, A T

    2016-01-01

    We study radiative capture reactions using quasi-separable potentials. This procedure allows an easier treatment of non-local effects that can be extended to three-body problems. Using this technique, we calculate the neutron and proton radiative capture cross sections on 12 C. The results obtained are shown to be in good agreement with the available experimental data. (paper)

  13. Big bang nucleosynthesis: The strong nuclear force meets the weak anthropic principle

    International Nuclear Information System (INIS)

    MacDonald, J.; Mullan, D. J.

    2009-01-01

    Contrary to a common argument that a small increase in the strength of the strong force would lead to destruction of all hydrogen in the big bang due to binding of the diproton and the dineutron with a catastrophic impact on life as we know it, we show that provided the increase in strong force coupling constant is less than about 50% substantial amounts of hydrogen remain. The reason is that an increase in strong force strength leads to tighter binding of the deuteron, permitting nucleosynthesis to occur earlier in the big bang at higher temperature than in the standard big bang. Photodestruction of the less tightly bound diproton and dineutron delays their production to after the bulk of nucleosynthesis is complete. The decay of the diproton can, however, lead to relatively large abundances of deuterium.

  14. Astrophysical Li-7 as a product of big bang nucleosynthesis and galactic cosmic-ray spallation

    Science.gov (United States)

    Olive, Keith A.; Schramm, David N.

    1992-01-01

    The astrophysical Li-7 abundance is considered to be largely primordial, while the Be and B abundances are thought to be due to galactic cosmic ray (GCR) spallation reactions on top of a much smaller big bang component. But GCR spallation should also produce Li-7. As a consistency check on the combination of big bang nucleosynthesis and GCR spallation, the Be and B data from a sample of hot population II stars is used to subtract from the measured Li-7 abundance an estimate of the amount generated by GCR spallation for each star in the sample, and then to add to this baseline an estimate of the metallicity-dependent augmentation of Li-7 due to spallation. The singly reduced primordial Li-7 abundance is still consistent with big bang nucleosynthesis, and a single GCR spallation model can fit the Be, B, and corrected Li-7 abundances for all the stars in the sample.

  15. Neutrino masses and mixings: Big Bang and Supernova nucleosynthesis and neutrino dark matter

    International Nuclear Information System (INIS)

    Fuller, George M.

    1999-01-01

    The existence of small mixings between light active and sterile neutrino species could have implications for Big Bang and Supernova Heavy Element Nucleosynthesis. As well, such mixing would force us to abandon cherished constraints on light neutrino Dark Matter. Two proposed 4-neutrino mass and mixing schemes, for example, can both accomodate existing experimental results and lead to elegant solutions to the neutron-deficit problem for r-Process nucleosynthesis from neutrino-heated supernova ejecta. Each of these solutions is based on matter-enhanced (MSW) active-sterile neutrino transformation. In plausible extensions of these schemes to the early universe, Shi and Fuller have shown that relatively light mass (∼200 eV to ∼10 keV) sterile neutrinos produced via active-sterile MSW conversion can have a ''cold'' energy spectrum. Neutrinos produced in this way circumvent the principal problem of light neutrino dark matter and would be, essentially, Cold Dark Matter

  16. The Main Path to C, N, O Elements in Big Bang Nucleosynthesis

    International Nuclear Information System (INIS)

    Su-Qing, Hou; Kai-Su, Wu; Yong-Shou, Chen; Neng-Chuan, Shu; Zhi-Hong, Li

    2010-01-01

    The production of C, N, O elements in a standard big bang nucleosynthesis scenario is investigated. Using the up-to-date data of nuclear reactions in BBN, in particular the 8 Li (n,γ) 9 Li which has been measured in China Institute of Atomic Energy, a full nucleosynthesis network calculation of BBN is carried out. Our calculation results show that the abundance of 12 C is increased for an order of magnitude after addition of the reaction chain 8 Li(n,γ) 9 Li(α,n) 12 B(β) 12 C, which was neglected in previous studies. We find that this sequence provides the main channel to convert the light elements into C, N, O in standard BBN. (nuclear physics)

  17. Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density

    International Nuclear Information System (INIS)

    Smith, Michael Scott; Roberts, Luke F.; Hix, William Raphael; Bruner, Blake D.; Kozub, R.L.; Tytler, David; Fuller, George M.; Lingerfelt, Eric J.; Nesaraja, Caroline D

    2008-01-01

    We performed new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio η given current observational uncertainties. We also performed sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the η constraint.

  18. Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density Constraints

    International Nuclear Information System (INIS)

    Smith, Michael S.; Roberts, Luke F.; Hix, W. Raphael; Bruner, Blake D.; Kozub, Raymond L.; Tytler, David; Fuller, George M.; Lingerfelt, Eric; Nesaraja, Caroline D.

    2008-01-01

    We performed new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio η given current observational uncertainties. We also performed sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the η constraint

  19. Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density Constraints

    International Nuclear Information System (INIS)

    Smith, Michael Scott; Bruner, Blake D; KOZUB, RAYMOND L.; Roberts, Luke F.; Tytler, David; Fuller, George M.; Lingerfelt, Eric; Hix, William Raphael; Nesaraja, Caroline D

    2008-01-01

    We ran new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio eta given current observational uncertainties. We also ran sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the eta constraint

  20. Distortions in the cosmic background radiation and big-bang 4He nucleosynthesis

    International Nuclear Information System (INIS)

    Mathews, G.J.; Alhassid, Y.; Fuller, G.M.

    1981-01-01

    The observed distortion of the cosmic background radiation is analyzed in the framework of information theory to derive a simple form of the photon occupation probability. Taking this distribution function as indicative of the Lagrange parameters which might characterize the era of nucleosynthesis during the big bang, and assuming equilibrium among the constituents present, we find that the primordial 4 He abundance may be reduced by as much as 15% from the standard big-bang prediction

  1. Lithium isotopic abundances in metal-poor stars: a problem for standard big bang nucleosynthesis?

    International Nuclear Information System (INIS)

    Nissen, P.E.; Asplund, M.; Lambert, D.L.; Primas, F.; Smith, V.V.

    2005-01-01

    Spectral obtained with VLT/UVES suggest the existence of the 6 Li isotope in several metal-poor stars at a level that challenges ideas about its synthesis. The 7 Li abundance is, on the other hand, a factor of three lower than predicted by standard Big Bang nucleosynthesis theory. Both problems may be explained if decaying suppersymmetric particles affect the synthesis of light elements in the Big Bang. (orig.)

  2. The effects of irradiation and proton implantation on the density of mobile protons in SiO2 films

    International Nuclear Information System (INIS)

    Vanheusden, K.

    1998-04-01

    Proton implantation into the buried oxide of Si/SiO 2 /Si structures does not introduce mobile protons. The cross section for capture of radiation-induced electrons by mobile protons is two orders of magnitude smaller than for electron capture by trapped holes. The data provide new insights into the atomic mechanisms governing the generation and radiation tolerance of mobile protons in SiO 2 . This can lead to improved techniques for production and radiation hardening of radiation tolerant memory devices

  3. Trojan Horse cross section measurements and their impact on primordial nucleosynthesis

    Science.gov (United States)

    Pizzone, R. G.; Spartá, R.; Bertulani, C.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A.; Tumino, A.

    2018-01-01

    Big Bang Nucleosynthesis (BBN) nucleosynthesis requires several nuclear physics inputs and, among them, an important role is played by nuclear reaction rates. They are among the most important input for a quantitative description of the early Universe. An up-to-date compilation of direct cross sections of d(d,p)t, d(d,n)3He and 3He(d,p)4He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM) to study reactions of relevance for the BBN and measure their astrophysical S(E)-factor. The result of these recent measurements is reviewed and compared with the available direct data. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN (0.01nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances of D, 3,4He and 7Li. These ones were then compared with the observational primordial abundance estimates in different astrophysical sites. A comparison was also performed with calculations using other reaction rates compilations available in literature.

  4. Effects of neutrino oscillations on nucleosynthesis and neutrino signals for an 18 M⊙ supernova model

    Science.gov (United States)

    Wu, Meng-Ru; Qian, Yong-Zhong; Martínez-Pinedo, Gabriel; Fischer, Tobias; Huther, Lutz

    2015-03-01

    In this paper, we explore the effects of neutrino flavor oscillations on supernova nucleosynthesis and on the neutrino signals. Our study is based on detailed information about the neutrino spectra and their time evolution from a spherically symmetric supernova model for an 18 M⊙ progenitor. We find that collective neutrino oscillations are not only sensitive to the detailed neutrino energy and angular distributions at emission, but also to the time evolution of both the neutrino spectra and the electron density profile. We apply the results of neutrino oscillations to study the impact on supernova nucleosynthesis and on the neutrino signals from a Galactic supernova. We show that in our supernova model, collective neutrino oscillations enhance the production of rare isotopes 138La and 180Ta but have little impact on the ν p -process nucleosynthesis. In addition, the adiabatic Mikheyev-Smirnov-Wolfenstein flavor transformation, which occurs in the C /O and He shells of the supernova, may affect the production of light nuclei such as 7Li and 11B. For the neutrino signals, we calculate the rate of neutrino events in the Super-Kamiokande detector and in a hypothetical liquid argon detector. Our results suggest the possibility of using the time profiles of the events in both detectors, along with the spectral information of the detected neutrinos, to infer the neutrino mass hierarchy.

  5. Primordial nucleosynthesis in the Rh = ct cosmology: pouring cold water on the simmering Universe

    Science.gov (United States)

    Lewis, Geraint F.; Barnes, Luke A.; Kaushik, Rajesh

    2016-07-01

    Primordial nucleosynthesis is rightly hailed as one of the great successes of the standard cosmological model. Here we consider the initial forging of elements in the recently proposed Rh = ct universe, a cosmology that demands linear evolution of the scale factor. Such a universe cools extremely slowly compared to standard cosmologies, considerably depleting the available neutrons during nucleosynthesis; this has significant implications for the resultant primordial abundances of elements, predicting a minuscule quantity of helium which is profoundly at odds with observations. The production of helium can be enhanced in such a `simmering universe' by boosting the baryon to photon ratio, although more than an order of magnitude increase is required to bring the helium mass fraction into accordance with observations. However, in this scenario, the prolonged period of nucleosynthesis results of the efficient cooking of lighter into heavier elements, impacting the resultant abundances of all elements so that, other than hydrogen and helium, there are virtually no light elements present in the universe. Without the addition of substantial new physics in the early universe, it is difficult to see how the Rh = ct universe can be considered a viable cosmological model.

  6. Proton radiography to improve proton therapy treatment

    NARCIS (Netherlands)

    Takatsu, J.; van der Graaf, E. R.; van Goethem, Marc-Jan; van Beuzekom, M.; Klaver, T.; Visser, Jan; Brandenburg, S.; Biegun, A. K.

    The quality of cancer treatment with protons critically depends on an accurate prediction of the proton stopping powers for the tissues traversed by the protons. Today, treatment planning in proton radiotherapy is based on stopping power calculations from densities of X-ray Computed Tomography (CT)

  7. General properties of astrophysical reaction rates in explosive nucleosynthesis

    International Nuclear Information System (INIS)

    Rauscher, Thomas

    2013-01-01

    Fundamental differences in the prediction of reaction rates with intermediate and heavy target nuclei compared to the ones with light nuclei are discussed, with special emphasis on stellar modifications of the rates. Ground and excited state contributions to the stellar rates are quantified, deriving a linear weighting of excited state contributions despite of a Boltzmann population of the nuclear states. A Coulomb suppression effect of the excited state contributions is identified, acting against the usual Q-value rule in some reactions. The proper inclusion of experimental data in revised stellar rates is shown, containing revised uncertainties. An application to the s-process shows that the actual uncertainties in the neutron capture rates are larger than would be expected from the experimental errors alone. Sensitivities of reaction rates and cross sections are defined and their application in reaction studies is discussed. The conclusion provides a guide to experiment as well as theory on how to best improve the rates used in astrophysical simulations and how to assess their uncertainties.

  8. DFT studies on proton-ethylene collisions

    International Nuclear Information System (INIS)

    Wang Zhiping; Zhang Fengshou; Wang Jing

    2012-01-01

    In the framework of the time-dependent local-density approximation (TDLDA)which applied to valence electrons, coupled non-adiabatically to molecular dynamics of ions, the microscopic mechanisms of collisions between energetic protons and ethylene are studied. Not only the amount of energy lost of the projectile, but also the electron and vibration excitations of the target are identified. In addition, the influences of the collision orientation on the energy loss of the proton and excitation dynamics of ethylene are discussed. It is found that the ionization is enhanced and more electrons are captured by the proton when the proton with the impact energy less than 250 eV moves perpendicularly to the molecular plane. A strong relation between the proton energy lost and the impact orientation is obtained when the impact energy is larger than 250 eV. (authors)

  9. Study of the 17Ne Coulomb dissociation process and its role for the rp process of nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Marganiec, Justyna [TU Darmstadt (Germany); EMMI, GSI Darmstadt (Germany); Wamers, Felix [EMMI, GSI Darmstadt (Germany); TU Darmstadt (Germany); GSI Darmstadt (Germany); FIAS, Frankfurt am Main (Germany); Aumann, Thomas [TU Darmstadt (Germany); GSI Darmstadt (Germany); Egorova, Irina [BLTP JINR Dubna (Russian Federation); Grigorenko, Leonid [FLNR JINR Dubna (Russian Federation); RRC KI, Moscow (Russian Federation); Heil, Michael [GSI Darmstadt (Germany); Perfenova, Yuliya [FLNR JINR Dubna (Russian Federation); INP, Moscow (Russian Federation); Plag, Ralf [GSI Darmstadt (Germany); Goethe-Universitaet, Frankfurt am Main (Germany); Collaboration: R3B-Collaboration

    2014-07-01

    The study of {sup 17}Ne Coulomb dissociation process gives us a possibility to study the time-reversed reaction {sup 15}O(2p,γ){sup 17}Ne, with the detailed balance theorem. This reaction could serve as a bypass of {sup 15}O waiting point during the rp process, and move the initial CNO material towards heavier nuclei. The two-proton capture can proceed sequentially or directly from the three-body continuum. And the reaction rate can be enhanced by a few orders of magnitude by taking the three-body continuum into account. The Coulomb dissociation method is the one way to experimentally determine the three-body radiative capture cross section, which is needed to verify theoretical calculations, and which was not experimentally determined yet. The experiment has been performed at the LAND/R3B setup at GSI.

  10. Proton diffraction

    International Nuclear Information System (INIS)

    Den Besten, J.L.; Jamieson, D.N.; Allen, L.J.

    1998-01-01

    The Lindhard theory on ion channeling in crystals has been widely accepted throughout ion beam analysis for use in simulating such experiments. The simulations use a Monte Carlo method developed by Barret, which utilises the classical 'billiard ball' theory of ions 'bouncing' between planes or tubes of atoms in the crystal. This theory is not valid for 'thin' crystals where the planes or strings of atoms can no longer be assumed to be of infinite proportions. We propose that a theory similar to that used for high energy electron diffraction can be applied to MeV ions, especially protons, in thin crystals to simulate the intensities of transmission channeling and of RBS spectra. The diffraction theory is based on a Bloch wave solution of the Schroedinger equation for an ion passing through the periodic crystal potential. The widely used universal potential for proton-nucleus scattering is used to construct the crystal potential. Absorption due to thermal diffuse scattering is included. Experimental parameters such as convergence angle, beam tilt and scanning directions are considered in our calculations. Comparison between theory and experiment is encouraging and suggests that further work is justified. (authors)

  11. Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n_TOF facility (CERN)

    Science.gov (United States)

    Casanovas, A.; Domingo-Pardo, C.; Guerrero, C.; Lerendegui-Marco, J.; Calviño, F.; Tarifeño-Saldivia, A.; Dressler, R.; Heinitz, S.; Kivel, N.; Quesada, J. M.; Schumann, D.; Aberle, O.; Alcayne, V.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Barbagallo, M.; Bečvář, F.; Bellia, G.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Busso, M.; Caamaño, M.; Caballero-Ontanaya, L.; Calviani, M.; Cano-Ott, D.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Damone, L. A.; Diakaki, M.; Dietz, M.; Dupont, E.; Durán, I.; Eleme, Z.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Furman, V.; Göbel, K.; Gawlik, A.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González-Romero, E.; Gunsing, F.; Heyse, J.; Jenkins, D. G.; Käppeler, F.; Kadi, Y.; Katabuchi, T.; Kimura, A.; Kokkoris, M.; Kopatch, Y.; Krtička, M.; Kurtulgil, D.; Ladarescu, I.; Lederer-Woods, C.; Meo, S. Lo; Lonsdale, S. J.; Macina, D.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Michalopoulou, V.; Milazzo, P. M.; Mingrone, F.; Musumarra, A.; Negret, A.; Nolte, R.; Ogállar, F.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Persanti, L.; Porras, I.; Praena, J.; Radeck, D.; Ramos, D.; Rauscher, T.; Reifarth, R.; Rochman, D.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Simone, S.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Talip, T.; Tassan-Got, L.; Tsinganis, A.; Ulrich, J.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T.; Žugec, P.; Köster, U.

    2018-05-01

    The neutron capture cross section of some unstable nuclei is especially relevant for s-process nucleosynthesis studies. This magnitude is crucial to determine the local abundance pattern, which can yield valuable information of the s-process stellar environment. In this work we describe the neutron capture (n,γ) measurement on two of these nuclei of interest, 204Tl and 171Tm, from target production to the final measurement, performed successfully at the n_TOF facility at CERN in 2014 and 2015. Preliminary results on the ongoing experimental data analysis will also be shown. These results include the first ever experimental observation of capture resonances for these two nuclei.

  12. Investigation of the impact of the $^{39}$Ar(n , $\\alpha)^{36}$S reaction on the nucleosynthesis of the rare isotope $^{36}$S

    CERN Multimedia

    Geltenbort, P

    2002-01-01

    The origin of the rare, neutron rich isotope $^{36}$S remains a debated question. One of the key reactions in the s-process nucleosynthesis network leading to $^{36}$S is $^{39}$Ar(n , $\\alpha) ^{36}\\!$S. This reaction has never been studied so far, which is due to the fact that $^{39}$Ar is a radioactive (T$_{1/2}$ = 269 y) gas, which is not commercially available. During a three days experimental campaign, an optimized $^{39}$Ar sample was prepared at ISOLDE. A dedicated titaniumoxide target (8 g/cm$^{2}$) was bombarded with 1 GeV protons from the PS Booster. In order to obtain a pure argon beam, a water-cooled transfer line was used to freeze-out less volatile isobars before they can reach the ion source. Adding stable argon with a calibrated leak to the ion source enabled to determine the ionization efficiency (3.5%). For the isotope separation, the low-mass side (GLM) of the General Purpose Separator was used. After magnetic separation, $^{39}$Ar ions (1+) were implanted at 60 keV in a 12 mm thick alumin...

  13. Radiative capture versus Coulomb dissociation

    International Nuclear Information System (INIS)

    Esbensen, H.; Physics

    2006-01-01

    Measurements of the Coulomb dissociation of 8 B have been used to infer the rate of the inverse radiative proton capture on 7 Be. The analysis is usually based on the assumptions that the two processes are related by detailed balance and described by E1 transitions. However, there are corrections to this relation. The Coulomb form factors for the two processes, for example, are not identical. There are also E2 transitions and higher-order effects in the Coulomb dissociation, and the nuclear induced breakup cannot always be ignored. While adding first-order E2 transitions enhances the decay energy spectrum, the other mechanisms cause a suppression at low relative energies. The net result may accidentally be close to the conventional first-order E1 calculation, but there are differences which cannot be ignored if accuracies of 10% or better are needed

  14. Radiative Capture versus Coulomb Dissociation

    International Nuclear Information System (INIS)

    Esbensen, Henning

    2006-01-01

    Measurements of the Coulomb dissociation of 8B have been used to infer the rate of the inverse radiative proton capture on 7Be. The analysis is usually based on the assumptions that the two processes are related by detailed balance and described by E1 transitions. However, there are corrections to this relation. The Coulomb form factors for the two processes, for example, are not identical. There are also E2 transitions and higher-order effects in the Coulomb dissociation, and the nuclear induced breakup cannot always be ignored. While adding first-order E2 transitions enhances the decay energy spectrum, the other mechanisms cause a suppression at low relative energies. The net result may accidentally be close to the conventional first-order E1 calculation, but there are differences which cannot be ignored if accuracies of 10% or better are needed

  15. (n,{gamma}) and (p,{gamma}) rates for s- and p-process nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kaeppeler, F [Forschungszentrum Karlsruhe, Karlsruhe (Germany)

    1998-06-01

    The late stages of stellar evolution are characterized by a series of nucleosynthesis events. With respect to the heavy elements, these are the s process associated with the helium burning layers in Red Giant stars as well as the r and p processes which occur in supernova explosions. In contrast to the explosive scenarios, the nuclear physics data for s-process studies can be determined in laboratory experiments as illustrated at few recent examples. The application of these techniques to measurements of relevance for the p process are also discussed. (orig.)

  16. (n,γ) and (p,γ) rates for s- and p-process nucleosynthesis

    International Nuclear Information System (INIS)

    Kaeppeler, F.

    1998-01-01

    The late stages of stellar evolution are characterized by a series of nucleosynthesis events. With respect to the heavy elements, these are the s process associated with the helium burning layers in Red Giant stars as well as the r and p processes which occur in supernova explosions. In contrast to the explosive scenarios, the nuclear physics data for s-process studies can be determined in laboratory experiments as illustrated at few recent examples. The application of these techniques to measurements of relevance for the p process are also discussed. (orig.)

  17. Astrophysical S-factor for destructive reactions of lithium-7 in big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Komatsubara, Tetsuro; Kwon, YoungKwan; Moon, JunYoung; Kim, Yong-Kyun [Rare Isotope Science Project, Institute for Basic Science, Daejeon (Korea, Republic of); Moon, Chang-Bum [Hoseo University, Asan, Chungnam (Korea, Republic of); Ozawa, Akira; Sasa, Kimikazu; Onishi, Takahiro; Yuasa, Toshiaki; Okada, Shunsuke; Saito, Yuta [Division of Physics, University of Tsukuba, Tsukuba, Ibaraki (Japan); Hayakawa, Takehito; Shizuma, Toshiyuki [Japan Atomic Energy Agency, Shirakata Shirane, Tokai, Ibaraki (Japan); Kubono, Shigeru [RIKEN, Hirosawa, Wako, Saitama (Japan); Kusakabe, Motohiko [School of Liberal Arts and Science, Korea Aerospace University (Korea, Republic of); Kajino, Toshitaka [National Astronomical Observatory, Osawa, Mitaka, Tokyo (Japan)

    2014-05-02

    One of the most prominent success with the Big Bang models is the precise reproduction of mass abundance ratio for {sup 4}He. In spite of the success, abundances of lithium isotopes are still inconsistent between observations and their calculated results, which is known as lithium abundance problem. Since the calculations were based on the experimental reaction data together with theoretical estimations, more precise experimental measurements may improve the knowledge of the Big Bang nucleosynthesis. As one of the destruction process of lithium-7, we have performed measurements for the reaction cross sections of the {sup 7}L({sup 3}He,p){sup 9}Be reaction.

  18. Hadronic decay of late-decaying particles and big-bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, Masahiro [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)]. E-mail: masahiro_kawasaki@mac.com; Kohri, Kazunori [Department of Earth and Space Science, Osaka University, Osaka 560-0043 (Japan); Moroi, Takeo [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

    2005-10-06

    We study the big-bang nucleosynthesis (BBN) scenario with late-decaying exotic particles with lifetime longer than {approx}1 s. With a late-decaying particle in the early universe, predictions of the standard BBN scenario can be significantly altered. Therefore, we derive constraints on its primordial abundance. We pay particular attention to hadronic decay modes of such particles. We see that the non-thermal production process of D, {sup 3}He and {sup 6}Li provides a stringent upper bound on the primordial abundance of late-decaying particles with hadronic branching ratio.

  19. Nucleosynthesis in neutrino-driven winds: Influence of the nuclear physics input

    International Nuclear Information System (INIS)

    Arcones, Almudena; Martinez-Pinedo, Gabriel

    2010-01-01

    We have performed hydrodynamical simulations of the long-time evolution of proto-neutron stars to study the nucleosynthesis using the resulting wind trajectories. Although the conditions found in the present wind models are not favourable for the production of heavy elements, a small enhancement of the entropy results in the production of r-process elements with A ∼ 195. This allows us to explore the sensitivity of their production to the hydrodynamical evolution (wind termination shock) and nuclear physics input used.

  20. Nucleosynthesis in neutrino-driven, aspherical supernova explosion of a massive star

    International Nuclear Information System (INIS)

    Fujimoto, S.; Hashimoto, M.; Ono, M.; Kotake, K.; Ohnishi, N.

    2011-01-01

    We examine explosive nucleosynthesis of p-nuclei during a delayed neutrino-driven, aspherical supernova explosion aided by standing accretion shock instability, based on two-dimensional hydrodynamic simulations of the explosion of a 15M · star. We find that p-nuclei are mainly produced through γ-processes, and that the nuclei lighter than 92 Mo are abundantly synthesized in slightly neutron-rich bubbles with electron fractions of Y e ≤0.48. 94 Mo, 96 Ru, and 98 Ru, are underproduced compared with the solar system, as in the spherical model.

  1. Proton imaging apparatus for proton therapy application

    International Nuclear Information System (INIS)

    Sipala, V.; Lo Presti, D.; Brianzi, M.; Civinini, C.; Bruzzi, M.; Scaringella, M.; Talamonti, C.; Bucciolini, M.; Cirrone, G.A.P.; Cuttone, G.; Randazzo, N.; Stancampiano, C.; Tesi, M.

    2011-01-01

    Radiotherapy with protons, due to the physical properties of these particles, offers several advantages for cancer therapy as compared to the traditional radiotherapy and photons. In the clinical use of proton beams, a p CT (Proton Computer Tomography) apparatus can contribute to improve the accuracy of the patient positioning and dose distribution calculation. In this paper a p CT apparatus built by the Prima (Proton Imaging) Italian Collaboration will be presented and the preliminary results will be discussed.

  2. Proton radioactivity from proton-rich nuclei

    International Nuclear Information System (INIS)

    Guzman, F.; Goncalves, M.; Tavares, O.A.P.; Duarte, S.B.; Garcia, F.; Rodriguez, O.

    1999-03-01

    Half-lives for proton emission from proton-rich nuclei have been calculated by using the effective liquid drop model of heavy-particle decay of nuclei. It is shown that this model is able to offer results or spontaneous proton-emission half-life-values in excellent agreement with the existing experimental data. Predictions of half-life-values for other possible proton-emission cases are present for null orbital angular momentum. (author)

  3. Radiative electron capture

    International Nuclear Information System (INIS)

    Biggerstaff, J.A.; Appleton, B.R.; Datz, S.; Moak, C.D.; Neelavathi, V.N.; Noggle, T.S.; Ritchie, R.H.; VerBeek, H.

    1975-01-01

    Some data are presented for radiative electron capture by fast moving ions. The radiative electron capture spectrum is shown for O 8+ in Ag, along with the energy dependence of the capture cross-section. A discrepancy between earlier data, theoretical prediction, and the present data is pointed out. (3 figs) (U.S.)

  4. Proton-90Zr interaction at sub-coulomb proton energies

    International Nuclear Information System (INIS)

    Laird, C.E.; Flynn, D.; Hershberger, R.L.; Gabbard, F.

    1985-01-01

    Measurements have been made of proton elastic scattering differential cross sections for proton scattering at 135 0 and 165 0 from 2 to 7 MeV, of inelastic scattering cross sections for proton scattering from 3.9 to 5.7 MeV, and of the radiative capture cross sections from 1.9 to 5.7 MeV detecting primary and cascade gamma rays. Optical potentials with Hauser-Feshbach and coupled-channel models have been used to analyze the data. This analysis yields an energy dependent absorptive potential of W = 2.63+.73 whose mean value of 5 MeV at E/sub p/ = 4 MeV is consistent with previously reported, but anomalously small values. The diffuseness of the real potential is .54 fm, which is consistent with values found for 92 Zr and 94 Zr. The adopted model values are used to deduce a total proton strength function which displays the features of both the 3s and the 3p single particle resonances

  5. Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

    Science.gov (United States)

    Dai, Wei-Ming; Guo, Zong-Kuan; Cai, Rong-Gen; Zhang, Yuan-Zhong

    2017-06-01

    We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density.

  6. Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Wei-Ming; Cai, Rong-Gen [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Physical Sciences, Beijing (China); Guo, Zong-Kuan [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Astronomy and Space Science, Beijing (China); Zhang, Yuan-Zhong [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)

    2017-06-15

    We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density. (orig.)

  7. Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

    International Nuclear Information System (INIS)

    Dai, Wei-Ming; Cai, Rong-Gen; Guo, Zong-Kuan; Zhang, Yuan-Zhong

    2017-01-01

    We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density. (orig.)

  8. Atom capture and loss in ion molecule collisions

    International Nuclear Information System (INIS)

    Breinig, M.; Lasley, S.E.; Gaither, C.C. III.

    1985-01-01

    Progress is reported in measuring the energy and angular distribution of protons emerging with velocity close to the beam velocity from the target region when Ar + beams collide with a CH 4 target and ArH + beams collide with a He target at asymptotically high speeds. The protons result from the transfer of a target constituent to the projectile (atom capture) or from the dissociation of the projectile molecule in the collision (atom loss). For atom capture processes the Thomas peak is clearly observed. 10 refs., 3 figs

  9. Deep Mixing of 3He: Reconciling Big Bang and Stellar Nucleosynthesis

    International Nuclear Information System (INIS)

    Eggleton, P P; Dearborn, D P; Lattanzio, J

    2006-01-01

    Low-mass stars, ∼ 1-2 solar masses, near the Main Sequence are efficient at producing 3 He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3 He with the predictions of both stellar and Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus we are able to remove the threat that 3 He production in low-mass stars poses to the Big Bang nucleosynthesis of 3 He

  10. Convergence of scalar-tensor theories towards general relativity and primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Serna, A; Alimi, J-M; Navarro, A

    2002-01-01

    In this paper, we analyse the conditions for convergence towards general relativity of scalar-tensor gravity theories defined by an arbitrary coupling function α (in the Einstein frame). We show that, in general, the evolution of the scalar field (φ) is governed by two opposite mechanisms: an attraction mechanism which tends to drive scalar-tensor models towards Einstein's theory, and a repulsion mechanism which has the contrary effect. The attraction mechanism dominates the recent epochs of the universe evolution if, and only if, the scalar field and its derivative satisfy certain boundary conditions. Since these conditions for convergence towards general relativity depend on the particular scalar-tensor theory used to describe the universe evolution, the nucleosynthesis bounds on the present value of the coupling function, α 0 , strongly differ from some theories to others. For example, in theories defined by α ∝ |φ| analytical estimates lead to very stringent nucleosynthesis bounds on α 0 (∼ -19 ). By contrast, in scalar-tensor theories defined by α ∝ φ much larger limits on α 0 (∼ -7 ) are found

  11. Recent results in explosive and s-process nucleosynthesis from measurements on radioactive and stable targets

    International Nuclear Information System (INIS)

    Koehler, P.E.; Kaeppeler, F.; Schatz, H.

    1993-01-01

    Measurements of (n,p) and (n,α) cross sections are crucial for a better understanding of many scenarios of nucleosynthesis. Current problems in which such reactions play a roll include the possible synthesis of heavy element during the big bang. The production of several rare isotopes in explosive nucleosynthesis, and a better understanding of the role of the s process in the synthesis of light and intermediate mass nuclei. We have recently completed measurements of several (n,p) and (n,α) cross sections of importance to nuclear astrophysics. The cross sections were measured in the range from thermal energy to approximately 1 MeV by using the white neutron source at the Manuel Lujan, Jr. Neutron Scattering Center (LANSCE) in Los Alamos. We have also made complementary measurements at the Karlsruhe Van de Graaff and at thee Oak Ridge Electron Linear Accelerator (ORELA). We discuss the impact of the results on nuclear astrophysics as well as recent improvements and future plans

  12. Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis.

    Science.gov (United States)

    Eggleton, Peter P; Dearborn, David S P; Lattanzio, John C

    2006-12-08

    Low-mass stars, approximately 1 to 2 solar masses, near the Main Sequence are efficient at producing the helium isotope 3He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3He with the predictions of both stellar and Big Bang nucleosynthesis. Here we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus, we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He.

  13. Constraints on lifetime and mass of heavy lepton neutrinos imposed by big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Miyama, Shoken; Sato, Katsuhiko

    1978-01-01

    If there exist massive neutral leptons (heavy neutrinos), they would have been produced in thermal equilibrium in the early stages of the universe. The effects of their presence and decay on the big bang nucleosynthesis are investigated in detail and abundances of the products 4 He, 2 H and 7 Li are compared with the observed cosmic abundances. We have determined a region in the lifetime-mass diagram of the heavy neutrino which should be ruled out in order for the big bang nucleosynthesis not to conflict with observed abundances of the elements. In addition, if a lower limit of the lifetime obtained from the Weinberg-Salam type theory, tau>=6 x 10 7 (1 MeV/m sub(νh)) 5 sec, is assumed, where m sub(νh) is the mass of the heavy neutrino, the mass range of 70 eV< m sub(νh)<10 MeV is ruled out. The other constraints on the mass and the lifetime obtained from astrophysical considerations are also discussed and summarized. (author)

  14. Big Bang nucleosynthesis: Accelerator tests and can Ω/sub B/ really be large

    International Nuclear Information System (INIS)

    Schramm, D.N.

    1987-10-01

    The first collider tests of cosmological theory are now underway. The number of neutrino families in nature, N/sub nu/, plays a key role in elementary particle physics as well as in the synthesis of the light elements during the early evolution of the Universe. Standard Big Bang Nucleosynthesis argues for N/sub nu/ = 3 +- 1. Current limits on N/sub nu/ from the CERN anti pp collider and e + e - colliders are presented and compared to the cosmological bound. Supernova SN 1987A is also shown to give a limit on N/sub nu/ comparable to current accelerator bounds. All numbers are found to be small thus verifying the Big Bang model at an earlier epoch than is possible by traditional astronomical observations. Future measurements at SLC and LEP will further tighten this argument. Another key prediction of the standard Big Bang Nucleosynthesis is that the baryon density must be small (Ω/sub B/ ≤ 0.1). Recent attempts to try to subvert this argument using homogeneities of various types are shown to run afoul of the 7 Li abundance which has now become a rather firm constraint. 18 refs., 2 figs

  15. Convergence of scalar-tensor theories towards general relativity and primordial nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Serna, A [Dept. Fisica y Computacion, Universidad Miguel Hernandez, E03202-Elche (Spain); Alimi, J-M [LAEC, CNRS-UMR 8631, Observatoire de Paris-Meudon, F92195-Meudon (France); Navarro, A [Dept. Fisica, Universidad de Murcia, E30071-Murcia (Spain)

    2002-03-07

    In this paper, we analyse the conditions for convergence towards general relativity of scalar-tensor gravity theories defined by an arbitrary coupling function {alpha} (in the Einstein frame). We show that, in general, the evolution of the scalar field ({phi}) is governed by two opposite mechanisms: an attraction mechanism which tends to drive scalar-tensor models towards Einstein's theory, and a repulsion mechanism which has the contrary effect. The attraction mechanism dominates the recent epochs of the universe evolution if, and only if, the scalar field and its derivative satisfy certain boundary conditions. Since these conditions for convergence towards general relativity depend on the particular scalar-tensor theory used to describe the universe evolution, the nucleosynthesis bounds on the present value of the coupling function, {alpha}{sub 0}, strongly differ from some theories to others. For example, in theories defined by {alpha} {proportional_to} |{phi}| analytical estimates lead to very stringent nucleosynthesis bounds on {alpha}{sub 0}({approx}<10{sup -19}). By contrast, in scalar-tensor theories defined by {alpha} {proportional_to} {phi} much larger limits on {alpha}{sub 0}({approx}<10{sup -7}) are found.

  16. Proton movies

    CERN Multimedia

    2009-01-01

    A humorous short film made by three secondary school students received an award at a Geneva film festival. Even without millions of dollars or Hollywood stars at your disposal, it is still possible to make a good science fiction film about CERN. That is what three students from the Collège Madame de Staël in Carouge, near Geneva, demonstrated. For their amateur short film on the LHC, they were commended by the jury of the video and multimedia festival for schools organised by the "Media in education" service of the Canton of Geneva’s Public Education Department. The film is a spoof of a television news report on the LHC start-up. In sequences full of humour and imagination, the reporter conducts interviews with a very serious "Professor Sairne", some protons preparing for their voyage and even the neutrons that were rejected by the LHC. "We got the idea of making a film about CERN at the end of the summer," explains Lucinda Päsche, one of the three students. "We did o...

  17. New measurement of neutron capture resonances of 209Bi

    CERN Document Server

    Domingo-Pardo, C.; Aerts, G.; Alvarez-Pol, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Cano-Ott, D.; Capote, R.; Carrillode Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillman, I.; Dolfini, R.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Gallino, R.; Goncalves, I.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Kadi, Y.; Kappeler, F.; Karamanis, D.; Karadimos, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krticka, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Mastinu, P.; Mengoni, A.; Milazzo, P.M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; Oshima, M.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J.L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, Alberto; Villamarin, D.; Vincente, M.C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.

    2006-01-01

    The neutron capture cross section of Bi209 has been measured at the CERN n TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Additional experimental sources of systematic error, such as the electronic threshold in the detectors, summing of gamma-rays, internal electron conversion, and the isomeric state in bismuth, have been taken into account. Gamma-ray absorption effects inside the sample have been corrected by employing a nonpolynomial weighting function. Because Bi209 is the last stable isotope in the reaction path of the stellar s-process, the Maxwellian averaged capture cross section is important for the recycling of the reaction flow by alpha-decays. In the relevant stellar range of thermal energies between kT=5 and 8 keV our new capture rate is about 16% higher than the presently accepted value used for nucleosynthesis calculations. At th...

  18. Contribution of Proton Capture Reactions to the Ascertained ...

    Indian Academy of Sciences (India)

    Upakul Mahanta

    2017-11-27

    Nov 27, 2017 ... to models of stellar development and the investigations of their properties have ... is also known for its multiple populations along with a bimodal distribution of the ...... its abundance have shown some decrement. This may be ...

  19. Effect of exotic long-lived sub-strongly interacting massive particles in big bang nucleosynthesis and a new solution to the Li problem

    Directory of Open Access Journals (Sweden)

    Kawasaki Masahiro

    2012-02-01

    Full Text Available The plateau of 7Li abundance as a function of the iron abundance by spectroscopic observations of metal-poor halo stars (MPHSs indicates its primordial origin. The observed abundance levels are about a factor of three smaller than the primordial 7Li abundance predicted in the standard Big Bang Nucleosynthesis (BBN model. This discrepancy might originate from exotic particle and nuclear processes operating in BBN epoch. Some particle models include heavy (m >> 1 GeV long-lived colored particles which would be confined inside exotic heavy hadrons, i.e., strongly interacting massive particles (SIMPs. We have found reactions which destroy 7Be and 7Li during BBN in the scenario of BBN catalyzed by a long-lived sub-strongly interacting massive particle (sub-SIMP, X. The reactions are non radiative X captures of 7 Be and 7Li which can be operative if the X particle interacts with nuclei strongly enough to drive 7 Be destruction but not strongly enough to form a bound state with 4 He of relative angular momentum L = 1. We suggest that 7Li problem can be solved as a result of a new process beyond the standard model through which the observable signature was left on the primordial Li abundance.

  20. BROOKHAVEN: Proton goal reached

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    On March 30 the 35-year old Alternating Gradient Synchrotron (AGS) exceeded its updated design goal of 6 x 10 13 protons per pulse (ppp), by accelerating 6.3 x 10 13 ppp, a world record intensity. This goal was set 11 years ago and achieving it called for the construction of a new booster and the reconstruction of much of the AGS. The booster was completed in 1991, and reached its design intensity of 1.5 x 10 13 ppp in 1993. The AGS reconstruction was finished in 1994, and by July of that year the AGS claimed a new US record intensity for a proton synchrotron of 4 x 10 13 ppp, using four booster pulses. Reaching the design intensity was scheduled for 1995. In 1994, the AGS had seemed to be solidly limited to 4 x 10 13 ppp, but in 1995 the operations crew, working on their own in the quiet of the owl shift, steadily improved the intensity, regularly setting new records, much to the bemusement of the machine physicists. The physicists, however, did contribute. A second harmonic radiofrequency cavity in the booster increased the radiofrequency bucket area for capture, raising the booster intensity from 1.7 to 2.1 x 10 13 ppp. In the AGS, new radiofrequency power supplies raised the available voltage from 8 to 13 kV, greatly enhancing the beam loading capabilities of the system. A powerful new transverse damping system successfully controlled instabilities that otherwise would have destroyed the beam in less than a millisecond. Also in the AGS, 35th harmonic octupole resonances were found

  1. BROOKHAVEN: Proton goal reached

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1995-09-15

    On March 30 the 35-year old Alternating Gradient Synchrotron (AGS) exceeded its updated design goal of 6 x 10{sup 13} protons per pulse (ppp), by accelerating 6.3 x 10{sup 13} ppp, a world record intensity. This goal was set 11 years ago and achieving it called for the construction of a new booster and the reconstruction of much of the AGS. The booster was completed in 1991, and reached its design intensity of 1.5 x 10{sup 13} ppp in 1993. The AGS reconstruction was finished in 1994, and by July of that year the AGS claimed a new US record intensity for a proton synchrotron of 4 x 10{sup 13} ppp, using four booster pulses. Reaching the design intensity was scheduled for 1995. In 1994, the AGS had seemed to be solidly limited to 4 x 10{sup 13} ppp, but in 1995 the operations crew, working on their own in the quiet of the owl shift, steadily improved the intensity, regularly setting new records, much to the bemusement of the machine physicists. The physicists, however, did contribute. A second harmonic radiofrequency cavity in the booster increased the radiofrequency bucket area for capture, raising the booster intensity from 1.7 to 2.1 x 10{sup 13} ppp. In the AGS, new radiofrequency power supplies raised the available voltage from 8 to 13 kV, greatly enhancing the beam loading capabilities of the system. A powerful new transverse damping system successfully controlled instabilities that otherwise would have destroyed the beam in less than a millisecond. Also in the AGS, 35th harmonic octupole resonances were found.

  2. Stimulus-driven capture and contingent capture

    NARCIS (Netherlands)

    Theeuwes, J.; Olivers, C.N.L.; Belopolsky, A.V.

    2010-01-01

    Whether or not certain physical events can capture attention has been one of the most debated issues in the study of attention. This discussion is concerned with how goal-directed and stimulus-driven processes interact in perception and cognition. On one extreme of the spectrum is the idea that

  3. AGB nucleosynthesis in the Large Magellanic Cloud. Detailed abundance analysis of the RV Tauri star MACHO 47.2496.8

    NARCIS (Netherlands)

    Reyniers, M.; Abia, C.; van Winckel, H.; Lloyd Evans, T.; Decin, L.K.E.; Eriksson, K.; Pollard, K.R.

    2007-01-01

    Context: .Abundance analysis of post-AGB objects as probes of AGB nucleosynthesis. Aims: .A detailed photospheric abundance study is performed on the carbon-rich post-AGB candidate MACHO 47.2496.8 in the LMC. Methods: .High-resolution, high signal-to-noise ESO VLT-UVES spectra of MACHO 47.2496.8 are

  4. The Lithium isotope ratio in Population II halo dwarfs: A proposed test of the late decaying massive particle nucleosynthesis scenario

    International Nuclear Information System (INIS)

    Brown, L.; Schramm, D.N.

    1988-02-01

    It is shown that observations of the Lithium isotope ratio in high surface temperature Population II stars may be critical to cosmological nucleosynthesis models. In particular, decaying particle scenarios as derived in some supersymmetric models may stand or fall with such observations. 15 refs., 3 figs., 2 tabs

  5. Proton-air and proton-proton cross sections

    Directory of Open Access Journals (Sweden)

    Ulrich Ralf

    2013-06-01

    Full Text Available Different attempts to measure hadronic cross sections with cosmic ray data are reviewed. The major results are compared to each other and the differences in the corresponding analyses are discussed. Besides some important differences, it is crucial to see that all analyses are based on the same fundamental relation of longitudinal air shower development to the observed fluctuation of experimental observables. Furthermore, the relation of the measured proton-air to the more fundamental proton-proton cross section is discussed. The current global picture combines hadronic proton-proton cross section data from accelerator and cosmic ray measurements and indicates a good consistency with predictions of models up to the highest energies.

  6. Capture ready study

    Energy Technology Data Exchange (ETDEWEB)

    Minchener, A.

    2007-07-15

    There are a large number of ways in which the capture of carbon as carbon dioxide (CO{sub 2}) can be integrated into fossil fuel power stations, most being applicable for both gas and coal feedstocks. To add to the choice of technology is the question of whether an existing plant should be retrofitted for capture, or whether it is more attractive to build totally new. This miscellany of choices adds considerably to the commercial risk of investing in a large power station. An intermediate stage between the non-capture and full capture state would be advantageous in helping to determine the best way forward and hence reduce those risks. In recent years the term 'carbon capture ready' or 'capture ready' has been coined to describe such an intermediate stage plant and is now widely used. However a detailed and all-encompassing definition of this term has never been published. All fossil fuel consuming plant produce a carbon dioxide gas byproduct. There is a possibility of scrubbing it with an appropriate CO{sub 2} solvent. Hence it could be said that all fossil fuel plant is in a condition for removal of its CO{sub 2} effluent and therefore already in a 'capture ready' state. Evidently, the practical reality of solvent scrubbing could cost more than the rewards offered by such as the ETS (European Trading Scheme). In which case, it can be said that although the possibility exists of capturing CO{sub 2}, it is not a commercially viable option and therefore the plant could not be described as ready for CO{sub 2} capture. The boundary between a capture ready and a non-capture ready condition using this definition cannot be determined in an objective and therefore universally acceptable way and criteria must be found which are less onerous and less potentially contentious to assess. 16 refs., 2 annexes.

  7. Exploring nuclear reactions relevant to Stellar and Big-Bang Nucleosynthesis using High-Energy-Density plasmas at OMEGA and the NIF

    Science.gov (United States)

    Gatu Johnson, M.

    2017-10-01

    Thermonuclear reaction rates and nuclear processes have been explored traditionally by means of accelerator experiments, which are difficult to execute at conditions relevant to Stellar Nucleosynthesis (SN) and Big Bang Nucleosynthesis (BBN). High-Energy-Density (HED) plasmas closely mimic astrophysical environments and are an excellent complement to accelerator experiments in exploring SN and BBN-relevant nuclear reactions. To date, our work using HED plasmas at OMEGA and NIF has focused on the complementary 3He+3He, T+3He and T +T reactions. First studies of the T +T reaction indicated the significance of the 5He ground-state resonance in the T +T neutron spectrum. Subsequent T +T experiments showed that the strength of this resonance varies with center-of-mass (c-m) energy in the range of 16-50 keV, a variation that is not fundamentally understood. Studies of the 3He+3He and T+3He reactions have also been conducted at OMEGA at c-m energies of 165 keV and 80 keV, respectively, and the results revealed three things. First, a large cross section for the T+3He- γ branch can be ruled out as an explanation for the anomalously high abundance of 6Li in primordial material. Second, the results contrasted to theoretical modeling indicate that the mirror-symmetry assumption is not enough to capture the differences between T +T and 3He+3He reactions. Third, the elliptical spectrum assumed in the analysis of 3He+3He data obtained in accelerator experiments is incorrect. Preliminary data from recent experiments at the NIF exploring the 3He+3He reaction at c-m energies of 60 keV and 100 keV also indicate that the underlying physics changes with c-m energy. In this talk, we describe these findings and future directions for exploring light-ion reactions at OMEGA and the NIF. The work was supported in part by the US DOE, LLE, and LLNL.

  8. Carbon Capture and Storage

    NARCIS (Netherlands)

    Benson, S.M.; Bennaceur, K.; Cook, P.; Davison, J.; Coninck, H. de; Farhat, K.; Ramirez, C.A.; Simbeck, D.; Surles, T.; Verma, P.; Wright, I.

    2012-01-01

    Emissions of carbon dioxide, the most important long-lived anthropogenic greenhouse gas, can be reduced by Carbon Capture and Storage (CCS). CCS involves the integration of four elements: CO 2 capture, compression of the CO2 from a gas to a liquid or a denser gas, transportation of pressurized CO 2

  9. CAPTURED India Country Evaluation

    NARCIS (Netherlands)

    O'Donoghue, R.; Brouwers, J.H.A.M.

    2012-01-01

    This report provides the findings of the India Country Evaluation and is produced as part of the overall CAPTURED End Evaluation. After five years of support by the CAPTURED project the End Evaluation has assessed that results are commendable. I-AIM was able to design an approach in which health

  10. Interatomic Coulombic electron capture

    International Nuclear Information System (INIS)

    Gokhberg, K.; Cederbaum, L. S.

    2010-01-01

    In a previous publication [K. Gokhberg and L. S. Cederbaum, J. Phys. B 42, 231001 (2009)] we presented the interatomic Coulombic electron capture process--an efficient electron capture mechanism by atoms and ions in the presence of an environment. In the present work we derive and discuss the mechanism in detail. We demonstrate thereby that this mechanism belongs to a family of interatomic electron capture processes driven by electron correlation. In these processes the excess energy released in the capture event is transferred to the environment and used to ionize (or to excite) it. This family includes the processes where the capture is into the lowest or into an excited unoccupied orbital of an atom or ion and proceeds in step with the ionization (or excitation) of the environment, as well as the process where an intermediate autoionizing excited resonance state is formed in the capturing center which subsequently deexcites to a stable state transferring its excess energy to the environment. Detailed derivation of the asymptotic cross sections of these processes is presented. The derived expressions make clear that the environment assisted capture processes can be important for many systems. Illustrative examples are presented for a number of model systems for which the data needed to construct the various capture cross sections are available in the literature.

  11. Proton therapy device

    International Nuclear Information System (INIS)

    Tronc, D.

    1994-01-01

    The invention concerns a proton therapy device using a proton linear accelerator which produces a proton beam with high energies and intensities. The invention lies in actual fact that the proton beam which is produced by the linear accelerator is deflected from 270 deg in its plan by a deflecting magnetic device towards a patient support including a bed the longitudinal axis of which is parallel to the proton beam leaving the linear accelerator. The patient support and the deflecting device turn together around the proton beam axis while the bed stays in an horizontal position. The invention applies to radiotherapy. 6 refs., 5 figs

  12. Evidence for supernova injection into the solar nebula and the decoupling of r-process nucleosynthesis.

    Science.gov (United States)

    Brennecka, Gregory A; Borg, Lars E; Wadhwa, Meenakshi

    2013-10-22

    The isotopic composition of our Solar System reflects the blending of materials derived from numerous past nucleosynthetic events, each characterized by a distinct isotopic signature. We show that the isotopic compositions of elements spanning a large mass range in the earliest formed solids in our Solar System, calcium-aluminum-rich inclusions (CAIs), are uniform, and yet distinct from the average Solar System composition. Relative to younger objects in the Solar System, CAIs contain positive r-process anomalies in isotopes A 140. This fundamental difference in the isotopic character of CAIs around mass 140 necessitates (i) the existence of multiple sources for r-process nucleosynthesis and (ii) the injection of supernova material into a reservoir untapped by CAIs. A scenario of late supernova injection into the protoplanetary disk is consistent with formation of our Solar System in an active star-forming region of the galaxy.

  13. Baryonic density of the universe: Big Bang nucleosynthesis versus CMB observations

    International Nuclear Information System (INIS)

    Vangioni-Flam, E.; Coc, A.; Casse, M.

    2003-01-01

    Thanks to recent nuclear reaction rate compilations (NACRE[2]) and new experimental and theoretical works in nuclear physics, we have updated Standard Big Bang Nucleosynthesis (SBBN) calculations. The results are compared to the most representative light element abundances, measured in pristine astrophysical media to derive the baryonic density of the Universe. We confront Ω b h 2 obtained in this study with other values deduced from recent independent approaches as the observations of the anisotropies of the Cosmic Microwave Background (BOOMERANG, CBI, DASI, MAXIMA and VSA experiments) or the Lyman-α forest at high redshifts. Comparison between these results is a test of their consistency and could provide a better determination of this important cosmological parameter

  14. Constraining f(T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN

    Energy Technology Data Exchange (ETDEWEB)

    Capozziello, S. [Universita di Napoli ' ' Federico II' ' , Complesso Universitario di Monte Sant' Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Napoli (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Napoli (Italy); Gran Sasso Science Institute, L' Aquila (Italy); Lambiase, G. [University of Salerno, Dipartimento di Fisica E.R. Cainaiello, Fisciano (Italy); INFN, Gruppo Collegato di Salerno, Sezione di Napoli, Fisciano (Italy); Saridakis, E.N. [National Technical University of Athens, Department of Physics, Athens (Greece); Baylor University, CASPER, Physics Department, Waco, TX (United States)

    2017-09-15

    We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f(T) gravity. The three most studied viable f(T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f(T) models can successfully satisfy the BBN constraints. (orig.)

  15. Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios

    CERN Document Server

    Cyburt, Richard H; Fields, Brian D; Luo, Feng; Olive, Keith A; Spanos, Vassilis C

    2009-01-01

    The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical...

  16. Big-bang nucleosynthesis and the baryon density of the universe.

    Science.gov (United States)

    Copi, C J; Schramm, D N; Turner, M S

    1995-01-13

    For almost 30 years, the predictions of big-bang nucleosynthesis have been used to test the big-bang model to within a fraction of a second of the bang. The agreement between the predicted and observed abundances of deuterium, helium-3, helium-4, and lithium-7 confirms the standard cosmology model and allows accurate determination of the baryon density, between 1.7 x 10(-31) and 4.1 x 10(-31) grams per cubic centimeter (corresponding to about 1 to 15 percent of the critical density). This measurement of the density of ordinary matter is pivotal to the establishment of two dark-matter problems: (i) most of the baryons are dark, and (ii) if the total mass density is greater than about 15 percent of the critical density, as many determinations indicate, the bulk of the dark matter must be "non-baryonic," composed of elementary particles left from the earliest moments.

  17. Constraining f(T) teleparallel gravity by big bang nucleosynthesis: f(T) cosmology and BBN.

    Science.gov (United States)

    Capozziello, S; Lambiase, G; Saridakis, E N

    2017-01-01

    We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f ( T ) gravity. The three most studied viable f ( T ) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f ( T ) models can successfully satisfy the BBN constraints.

  18. Effects of sterile neutrino and extra-dimension on big bang nucleosynthesis

    Science.gov (United States)

    Jang, Dukjae; Kusakabe, Motohiko; Cheoun, Myung-Ki

    2018-04-01

    We study effects of the sterile neutrino in the five-dimensional universe on the big bang nucleosynthesis (BBN). Since the five-dimensional universe model leads to an additional term in the Friedmann equation and the energy density of the sterile neutrino increases the total energy density, this model can affect the primordial abundance via changing the cosmic expansion rate. The energy density of the sterile neutrino can be determined by a rate equation for production of the sterile neutrino. We show that not only the mixing angle and the mass of the sterile neutrino, but also a resonant effect in the oscillation between sterile and active neutrinos is important to determine a relic abundance of the sterile neutrino. In this study, we also investigate how the sterile neutrino in extra-dimensional model can affect the BBN, and constrain the parameters related to the above properties of the sterile neutrino by using the observational primordial abundances of light elements.

  19. 178th International School of Physics "Enrico Fermi" : From the Big Bang to the Nucleosynthesis

    CERN Document Server

    Nappi, E

    2011-01-01

    Physicists have devoted much effort to reproducing the conditions of the primordial universe in laboratory conditions in their quest to work out a comprehensive theory of the appearance and evolution of nuclear matter. Whether it be trying to recreate the predicted primordial state of high-energy density matter in which quarks and gluons are effectively deconfined - the so-called Quark Gluon Plasma (QGP) - or exploring the structure and reaction properties of very unstable nuclei in experiments using radioactive beams, they have striven to understand the events which characterized the Big Bang and the various nucleosynthesis mechanisms which occur in the stars. This book contains the proceedings of the 2010 Enrico Fermi summer school held in Varenna, Italy, in July 2010, and devoted to the present understanding of the primordial universe and the origin of the elements, as achieved by studying nuclei and their constituents in extreme regimes of energy and composition. Subjects covered include: QGP formation; e...

  20. Revisiting big-bang nucleosynthesis constraints on long-lived decaying particles

    Science.gov (United States)

    Kawasaki, Masahiro; Kohri, Kazunori; Moroi, Takeo; Takaesu, Yoshitaro

    2018-01-01

    We study the effects of long-lived massive particles, which decayed during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundance of light elements. Compared to previous studies, (i) the reaction rates of standard BBN reactions are updated, (ii) the most recent observational data on the light element abundance and cosmological parameters are used, (iii) the effects of the interconversion of energetic nucleons at the time of inelastic scattering with background nuclei are considered, and (iv) the effects of the hadronic shower induced by energetic high-energy antinucleons are included. We compare the theoretical predictions on the primordial abundance of light elements with the latest observational constraints, and we derive upper bounds on the relic abundance of the decaying particle as a function of its lifetime. We also apply our analysis to an unstable gravitino, the superpartner of a graviton in supersymmetric theories, and obtain constraints on the reheating temperature after inflation.

  1. Testing the Friedmann equation: The expansion of the universe during big-bang nucleosynthesis

    International Nuclear Information System (INIS)

    Carroll, Sean M.; Kaplinghat, Manoj

    2002-01-01

    In conventional general relativity, the expansion rate H of a Robertson-Walker universe is related to the energy density by the Friedmann equation. Aside from the present day, the only epoch at which we can constrain the expansion history in a model-independent way is during big-bang nucleosynthesis (BBN). We consider a simple two-parameter characterization of the behavior of H during BBN and derive constraints on this parameter space, finding that the allowed region of parameter space is essentially one dimensional. We also study the effects of a large neutrino asymmetry within this framework. Our results provide a simple way to compare an alternative cosmology to the observational requirement of matching the primordial abundances of the light elements

  2. Constraining f(T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN

    International Nuclear Information System (INIS)

    Capozziello, S.; Lambiase, G.; Saridakis, E.N.

    2017-01-01

    We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f(T) gravity. The three most studied viable f(T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f(T) models can successfully satisfy the BBN constraints. (orig.)

  3. Constraining f( T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN

    Science.gov (United States)

    Capozziello, S.; Lambiase, G.; Saridakis, E. N.

    2017-09-01

    We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f( T) gravity. The three most studied viable f( T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f( T) models can successfully satisfy the BBN constraints.

  4. Nuclear astrophysics: Recent results on CNO-cycle reactions and AGB nucleosynthesis

    International Nuclear Information System (INIS)

    La Cognata, M.

    2011-01-01

    Nuclear astrophysics aims to measure nuclear-reaction cross sections of astrophysical interest to be included into models to study stellar evolution and nucleosynthesis. Low energies, < 100 keV, are requested for this is the window where these processes are more effective. Two effects have prevented to achieve a satisfactory knowledge of the relevant nuclear processes, namely the Coulomb barrier exponentially suppressing the cross section and the presence of atomic electrons. These difficulties have triggered theoretical and experimental investigations to extend our knowledge down to astrophysical energies. For instance, indirect techniques such as the Trojan Horse Method and new experimental facilities such as deep underground laboratories have been devised yielding new cutting-edge results.

  5. Aspherical nucleosynthesis in a core-collapse supernova with 25 M {sub ☉} standard progenitor

    Energy Technology Data Exchange (ETDEWEB)

    Popov, M. V. [École Normale Supérieure de Lyon, CRAL (UMR CNRS 5574), Université de Lyon 1, 46 allée d' Italie, F-69007 Lyon (France); Filina, A. A.; Baranov, A. A.; Chardonnet, P. [LAPTh, Université de Savoie, 9, Chemin de Bellevue BP 110, F-74941 Annecy-le-Vieux Cedex (France); Chechetkin, V. M. [Keldysh Institute of Applied Mathematics RAS, Miusskaya sq. 4, 125047 Moscow (Russian Federation)

    2014-03-01

    The problem of nucleosynthesis was studied within an aspherical supernova model. The explosive burning was computed in a star of 25 M {sub ☉} initial mass on its final stage of evolution. The chemical composition of a presupernova was taken from realistic evolutionary computations. A piecewise parabolic method on a local stencil was applied to simulate the hydrodynamics of the explosion. The gravity was recomputed by a Poisson solver on a fine grid as the explosion developed. A detailed yield of chemical elements was performed as a post-processing step using the tracer particles method. The produced nuclei formed a layer-like structure enclosing large fragments of nickel and iron-group isotopes that were pushed away from the central region by an explosion along the polar direction. The light nuclei were preferentially moving along the equatorial plane forming a torus-like structure.

  6. Optional carbon capture

    Energy Technology Data Exchange (ETDEWEB)

    Alderson, T.; Scott, S.; Griffiths, J. [Jacobs Engineering, London (United Kingdom)

    2007-07-01

    In the case of IGCC power plants, carbon capture can be carried out before combustion. The carbon monoxide in the syngas is catalytically shifted to carbon dioxide and then captured in a standard gas absorption system. However, the insertion of a shift converter into an existing IGCC plant with no shift would mean a near total rebuild of the gasification waste heat recovery, gas treatment system and HRSG, with only the gasifier and gas turbine retaining most of their original features. To reduce the extent, cost and time taken for the revamping, the original plant could incorporate the shift, and the plant would then be operated without capture to advantage, and converted to capture mode of operation when commercially appropriate. This paper examines this concept of placing a shift converter into an IGCC plant before capture is required, and operating the same plant first without and then later with CO{sub 2} capture in a European context. The advantages and disadvantages of this 'capture ready' option are discussed. 6 refs., 2 figs., 4 tabs.

  7. Elastic proton-proton scattering at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Yip, K.

    2011-09-03

    Here we describe elastic proton+proton (p+p) scattering measurements at RHIC in p+p collisions with a special optics run of {beta}* {approx} 21 m at STAR, at the center-of-mass energy {radical}s = 200 GeV during the last week of the RHIC 2009 run. We present preliminary results of single and double spin asymmetries.

  8. Baryon production in proton-proton collisions

    International Nuclear Information System (INIS)

    Liu, F.M.; Werner, K.

    2002-01-01

    Motivated by the recent rapidity spectra of baryons and antibaryons in pp collisions at 158 GeV and the Ω-bar/Ω ratio discussion, we reviewed string formation mechanism and some string models. This investigation told us how color strings are formed in ultrarelativistic proton-proton collisions

  9. Prospects for direct neutron capture measurements on s-process branching point isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, C.; Lerendegui-Marco, J.; Quesada, J.M. [Universidad de Sevilla, Dept. de Fisica Atomica, Molecular y Nuclear, Sevilla (Spain); Domingo-Pardo, C. [CSIC-Universidad de Valencia, Instituto de Fisica Corpuscular, Valencia (Spain); Kaeppeler, F. [Karlsruhe Institute of Technology, Institut fuer Kernphysik, Karlsruhe (Germany); Palomo, F.R. [Universidad de Sevilla, Dept. de Ingenieria Electronica, Sevilla (Spain); Reifarth, R. [Goethe-Universitaet Frankfurt am Main, Frankfurt am Main (Germany)

    2017-05-15

    The neutron capture cross sections of several unstable key isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure directly due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n, γ) measurement, where high neutron fluxes and effective background rejection capabilities are required. At present there are about 21 relevant s-process branching point isotopes whose cross section could not be measured yet over the neutron energy range of interest for astrophysics. However, the situation is changing with some very recent developments and upcoming technologies. This work introduces three techniques that will change the current paradigm in the field: the use of γ-ray imaging techniques in (n, γ) experiments, the production of moderated neutron beams using high-power lasers, and double capture experiments in Maxwellian neutron beams. (orig.)

  10. Proton: the particle.

    Science.gov (United States)

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10(80). Protons were created at 10(-6) -1 second after the Big Bang at ≈1.37 × 10(10) years beforethe present. Proton life span has been experimentally determined to be ≥10(34) years; that is, the age of the universe is 10(-24)th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W(+), W(-), Z(0), and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter. Copyright © 2013 Elsevier Inc. All

  11. Proton: The Particle

    Energy Technology Data Exchange (ETDEWEB)

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10{sup 80}. Protons were created at 10{sup −6} –1 second after the Big Bang at ≈1.37 × 10{sup 10} years beforethe present. Proton life span has been experimentally determined to be ≥10{sup 34} years; that is, the age of the universe is 10{sup −24}th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W{sup +}, W{sup −}, Z{sup 0}, and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter.

  12. Neutron capture cross section measurement of $^{151}Sm$ at the CERN neutron Time of Flight Facility (nTOF)

    CERN Document Server

    Abbondanno, U; Alvarez-Velarde, F; Alvarez-Pol, H; Andriamonje, Samuel A; Andrzejewski, J; Badurek, G; Baumann, P; Becvar, F; Benlliure, J; Berthoumieux, E; Calviño, F; Cano-Ott, D; Capote, R; Cennini, P; Chepel, V; Chiaveri, Enrico; Colonna, N; Cortés, G; Cortina-Gil, D; Couture, A; Cox, J; Dababneh, S; Dahlfors, M; David, S; Dolfini, R; Domingo-Pardo, C; Durán, I; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Frais-Kölbl, H; Furman, W; Gonçalves, I; Gallino, R; Gonzalez-Romero, E; Goverdovski, A; Gramegna, F; Griesmayer, E; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martínez, A; Isaev, S; Jericha, E; Kappeler, F; Kadi, Y; Karadimos, D; Kerveno, M; Ketlerov, V; Köhler, P; Konovalov, V; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martinez-Val, J; Mastinu, P; Mengoni, A; Milazzo, P M; Molina-Coballes, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, Heinz; O'Brien, S; Pancin, J; Papaevangelou, T; Paradela, C; Pavlik, A; Pavlopoulos, P; Perlado, J M; Perrot, L; Pignatari, M; Plag, R; Plompen, A; Plukis, A; Poch, A; Policarpo, Armando; Pretel, C; Quesada, J; Raman, S; Rapp, W; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, Carlo; Rudolf, G; Rullhusen, P; Salgado, J; Soares, J C; Stéphan, C; Tagliente, G; Taín, J L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarín, D; Vincente, M C; Vlachoudis, V; Voss, F; Wendler, H; Wiescher, M; Wissha, K

    2004-01-01

    The measurement of **1**5**1Sm(n, gamma)**1**5**2Sm (samarium) cross section showed improved performance of the new spallation neutron facility. It covered a wide energy range with good resolution, high neutron flux, low backgrounds and a favourable duty factor. The samarium cross section was found to be of great importance for characterizing neutron capture nucleosynthesis in asymptotic giant stars. The combination of these features provided a promising basis for a broad experimental program directed towards application in astrophysics and advanced nuclear technologies. (Edited abstract)

  13. arXiv AlterBBN v2: A public code for calculating Big-Bang nucleosynthesis constraints in alternative cosmologies

    CERN Document Server

    Arbey, A.; Hickerson, K.P.; Jenssen, E.S.

    We present the version 2 of AlterBBN, an open public code for the calculation of the abundance of the elements from Big-Bang nucleosynthesis. It does not rely on any closed external library or program, aims at being user-friendly and allowing easy modifications, and provides a fast and reliable calculation of the Big-Bang nucleosynthesis constraints in the standard and alternative cosmologies.

  14. Processes involved in pion capture in hydrogen-containing molecules

    International Nuclear Information System (INIS)

    Horvath, D.

    1983-03-01

    A systematic analysis is presented of the possible elementary processes determining the fate of negative pions stopped in hydrogen-containing samples. Using a phenomenological description in comparison with the available experimental information on pion capture in hydrogen, it is shown that the formation and decay of pπ - atoms in compounds Zsub(m)Hsub(n) are determined mainly by the processes of Auger capture in a molecular orbit ZHπ - , transition from molecular to atomic orbit, transfer of pions to atoms Z in collisions pπ - +Z, and nuclear capture in collisions pπ - +H. The recent assumption of a considerable role of the processes of radiative atomic capture in bound hydrogen atoms, nuclear capture of pions by protons from the molecular state ZHπ - , or 'inner' transfer of the pion via tunnelling through the bond Z-H is not supported by the theory and contradicts the experimental data

  15. Some options for the muon collider capture and decay solenoids

    International Nuclear Information System (INIS)

    Green, M.A.

    1995-11-01

    This report discusses some of the problems associated with using solenoid magnets to capture the secondary particles that are created when an intense beam of 8 to 10 GeV protons interacts with the target at the center of the capture region. Hybrid capture solenoids with inductions of 28 T and a 22T are described. The first 14 to 15 T of the solenoid induction will be generated by a superconducting magnet. The remainder of the field will be generated by a Bitter type of water cooled solenoid. The capture solenoids include a transition section from the high field solenoid to a 7 T decay channel where pions and kaons that come off of the target decay into muons. A short 7 T solenoidal decay channel between the capture solenoid system and the phase rotation system is described. A concept for separation of negative and positive pions and kaons is briefly discussed

  16. Proton-transfer reactions in ionized gases

    International Nuclear Information System (INIS)

    Stiller, W.; Schmidt, R.; Schuster, R.

    1985-01-01

    Ion-molecule reactions play an important role in various radiolytic processes, e.g. gas-pulse radiolysis, environmental research. For a discussion of mechanisms rate coefficients have to be assessed. Here gas-phase rate coefficients of ion-(polar) molecule reactions are calculated using the ideas of interaction potentials, reactive cross-sections and distribution functions of the translational energies of both the reactants (ions I, molecules M). The starting point of our approach, directed especially to gas-phase proton-transfer reactions, is the idea that the rate coefficient k can be calculated as an ion-molecule capture-rate coefficient multiplied by a 'steric factor' representing the probability for proton transfer. Mutual capture of the reaction partners within a possible reaction zone is caused by the physical interaction between an ion and a polar molecule. A model is discussed. Results are presented. (author)

  17. r-Process Nucleosynthesis in the Early Universe Through Fast Mergers of Compact Binaries in Triple Systems

    Science.gov (United States)

    Bonetti, Matteo; Perego, Albino; Capelo, Pedro R.; Dotti, Massimo; Miller, M. Coleman

    2018-05-01

    Surface abundance observations of halo stars hint at the occurrence of r-process nucleosynthesis at low metallicity ([Fe/H] scale of the inner compact object binaries. Our results are highly sensitive to the assumed initial distribution of the inner binary semi-major axes. Distributions with mostly wide compact object binaries are most affected by the third object, resulting in a strong increase (by more than a factor of 2) in the fraction of fast coalescences. If instead the distribution preferentially populates very close compact binaries, general relativistic precession prevents the third body from increasing the inner binary eccentricity to very high values. In this last case, the fraction of coalescing binaries is increased much less by tertiaries, but the fraction of binaries that would coalesce within 108 yr even without a third object is already high. Our results provide additional support to the compact-binary merger scenario for r-process nucleosynthesis.

  18. 44Ti Nucleosynthesis Lines and Hard X-ray Continuum in Young SNRs: from INTEGRAL to Simbol-X

    Science.gov (United States)

    Renaud, M.; Terrier, R.; Trap, G.; Lebrun, F.; Decourchelle, A.; Vink, J.

    2009-05-01

    Supemovae and their remnants are the main Galactic nucleosynthesis sites and the privileged sources of Galactic cosmic rays. The youngest of such remnants can be studied through two distinct observational features: 44Ti γ-ray lines and the hard X-ray nonthermal continuum emission. The former gives unique information on the nucleosynthesis conditions occuring during the first stages of the explosion, while the latter provides clues on acceleration processes at supernova remnant shocks. In this contribution, we present new INTEGRAL results on Tycho, the remnant of a historical supernova, and on G1.9+0.3, which has been recently unveiled as the youngest Galactic supernova remnant. Expectations with Simbol-X are also addressed.

  19. 44Ti Nucleosynthesis Lines and Hard X-ray Continuum in Young SNRs: from INTEGRAL to Simbol-X

    International Nuclear Information System (INIS)

    Renaud, M.; Terrier, R.; Lebrun, F.; Trap, G.; Decourchelle, A.; Vink, J.

    2009-01-01

    Supemovae and their remnants are the main Galactic nucleosynthesis sites and the privileged sources of Galactic cosmic rays. The youngest of such remnants can be studied through two distinct observational features: 44 Tiγ-ray lines and the hard X-ray nonthermal continuum emission. The former gives unique information on the nucleosynthesis conditions occuring during the first stages of the explosion, while the latter provides clues on acceleration processes at supernova remnant shocks. In this contribution, we present new INTEGRAL results on Tycho, the remnant of a historical supernova, and on G1.9+0.3, which has been recently unveiled as the youngest Galactic supernova remnant. Expectations with Simbol-X are also addressed.

  20. Big-bang nucleosynthesis and the relic abundance of dark matter in a stau-neutralino coannihilation scenario

    International Nuclear Information System (INIS)

    Jittoh, Toshifumi; Koike, Masafumi; Sato, Joe; Yamanaka, Masato; Kohri, Kazunori; Shimomura, Takashi

    2008-01-01

    A scenario of the big-bang nucleosynthesis is analyzed within the minimal supersymmetric standard model, which is consistent with a stau-neutralino coannihilation scenario to explain the relic abundance of dark matter. We find that we can account for the possible discrepancy of the abundance of 7 Li between the observation and the prediction of the big-bang nucleosynthesis by taking the mass of the neutralino as 300 GeV and the mass difference between the stau and the neutralino as (100-120) MeV. We can therefore simultaneously explain the abundance of the dark matter and that of 7 Li by these values of parameters. The lifetime of staus in this scenario is predicted to be O(100-1000) sec.

  1. Spherical proton emitters

    International Nuclear Information System (INIS)

    Berg, S.; Semmes, P.B.; Nazarewicz, W.

    1997-01-01

    Various theoretical approaches to proton emission from spherical nuclei are investigated, and it is found that all the methods employed give very similar results. The calculated decay widths are found to be qualitatively insensitive to the parameters of the proton-nucleus potential, i.e., changing the potential parameters over a fairly large range typically changes the decay width by no more than a factor of ∼3. Proton half-lives of observed heavy proton emitters are, in general, well reproduced by spherical calculations with the spectroscopic factors calculated in the independent quasiparticle approximation. The quantitative agreement with experimental data obtained in our study requires that the parameters of the proton-nucleus potential be chosen carefully. It also suggests that deformed proton emitters will provide invaluable spectroscopic information on the angular momentum decomposition of single-proton orbitals in deformed nuclei. copyright 1997 The American Physical Society

  2. Proton therapy physics

    CERN Document Server

    2012-01-01

    Proton Therapy Physics goes beyond current books on proton therapy to provide an in-depth overview of the physics aspects of this radiation therapy modality, eliminating the need to dig through information scattered in the medical physics literature. After tracing the history of proton therapy, the book summarizes the atomic and nuclear physics background necessary for understanding proton interactions with tissue. It describes the physics of proton accelerators, the parameters of clinical proton beams, and the mechanisms to generate a conformal dose distribution in a patient. The text then covers detector systems and measuring techniques for reference dosimetry, outlines basic quality assurance and commissioning guidelines, and gives examples of Monte Carlo simulations in proton therapy. The book moves on to discussions of treatment planning for single- and multiple-field uniform doses, dose calculation concepts and algorithms, and precision and uncertainties for nonmoving and moving targets. It also exami...

  3. Proton solvation and proton transfer in chemical and electrochemical processes

    International Nuclear Information System (INIS)

    Lengyel, S.; Conway, B.E.

    1983-01-01

    This chapter examines the proton solvation and characterization of the H 3 O + ion, proton transfer in chemical ionization processes in solution, continuous proton transfer in conductance processes, and proton transfer in electrode processes. Topics considered include the condition of the proton in solution, the molecular structure of the H 3 O + ion, thermodynamics of proton solvation, overall hydration energy of the proton, hydration of H 3 O + , deuteron solvation, partial molal entropy and volume and the entropy of proton hydration, proton solvation in alcoholic solutions, analogies to electrons in semiconductors, continuous proton transfer in conductance, definition and phenomenology of the unusual mobility of the proton in solution, solvent structure changes in relation to anomalous proton mobility, the kinetics of the proton-transfer event, theories of abnormal proton conductance, and the general theory of the contribution of transfer reactions to overall transport processes

  4. Study of proton radioactivities

    Energy Technology Data Exchange (ETDEWEB)

    Davids, C.N.; Back, B.B.; Henderson, D.J. [and others

    1995-08-01

    About a dozen nuclei are currently known to accomplish their radioactive decay by emitting a proton. These nuclei are situated far from the valley of stability, and mark the very limits of existence for proton-rich nuclei: the proton drip line. A new 39-ms proton radioactivity was observed following the bombardment of a {sup 96}Ru target by a beam of 420-MeV {sup 78}Kr. Using the double-sided Si strip detector implantation system at the FMA, a proton group having an energy of 1.05 MeV was observed, correlated with the implantation of ions having mass 167. The subsequent daughter decay was identified as {sup 166}Os by its characteristic alpha decay, and therefore the proton emitter is assigned to the {sup 167}Ir nucleus. Further analysis showed that a second weak proton group from the same nucleus is present, indicating an isomeric state. Two other proton emitters were discovered recently at the FMA: {sup 171}Au and {sup 185}Bi, which is the heaviest known proton radioactivity. The measured decay energies and half-lives will enable the angular momentum of the emitted protons to be determined, thus providing spectroscopic information on nuclei that are beyond the proton drip line. In addition, the decay energy yields the mass of the nucleus, providing a sensitive test of mass models in this extremely proton-rich region of the chart of the nuclides. Additional searches for proton emitters will be conducted in the future, in order to extend our knowledge of the location of the proton drip line.

  5. Study on the dominant reaction path in nucleosynthesis during stellar evolution by means of the Monte Carlo method

    International Nuclear Information System (INIS)

    Yamamoto, K.; Hashizume, K.; Wada, T.; Ohta, M.; Suda, T.; Nishimura, T.; Fujimoto, M. Y.; Kato, K.; Aikawa, M.

    2006-01-01

    We propose a Monte Carlo method to study the reaction paths in nucleosynthesis during stellar evolution. Determination of reaction paths is important to obtain the physical picture of stellar evolution. The combination of network calculation and our method gives us a better understanding of physical picture. We apply our method to the case of the helium shell flash model in the extremely metal poor star

  6. The mass (charge) spectrum of superheavy nuclei fission fragments: the new perspectives for the theory of nucleosynthesis

    International Nuclear Information System (INIS)

    Maslyuk, V.T.

    2012-01-01

    A new approach to the problem of nucleosynthesis based on assumption of a nuclear matter or superheavy nuclei series fragmentation up to atomic nuclei is proposed. It is shown that studies of the mass (charge) fragments yields (MCFY) after nuclear matter disintegration is possible within proposed statistical theory. The data of MCFY calculation for exotic superheavy nuclei multifragmentation with A=300, 900 and 1200 and arbitrary Z values are demonstrated

  7. Limits on cosmological variation of strong interaction and quark masses from big bang nucleosynthesis, cosmic, laboratory and Oklo data

    International Nuclear Information System (INIS)

    Flambaum, V.V.; Shuryak, E.V.

    2002-01-01

    Recent data on the cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of the possible variation of other constants. We discuss the variation of strong scale and quark masses. We derive limits on their relative change from (i) primordial big bang nucleosynthesis, (ii) the Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals

  8. Constraining nuclear data via cosmological observations: Neutrino energy transport and big bang nucleosynthesis

    Directory of Open Access Journals (Sweden)

    Paris Mark

    2017-01-01

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

  9. Optimising the Target and Capture Sections of the Neutrino Factory

    CERN Document Server

    Hansen, Ole Martin; Stapnes, Steinar

    The Neutrino Factory is designed to produce an intense high energy neutrino beam from stored muons. The majority of the muons are obtained from the decay of pions, produced by a proton beam impinging on a free-flowing mercury-jet target and captured by a high magnetic field. It is important to capture a large fraction of the produced pions to maximize the intensity of the neutrino beam. Various optimisation studies have been performed with the aim of maximising the muon influx to the accelerator and thus the neutrino beam intensity. The optimisation studies were performed with the use of Monte Carlo simulation tools. The production of secondary particles, by interactions between the incoming proton beam and the mercury target, was optimised by varying the proton beam impact position and impact angles on the target. The proton beam and target interaction region was studied and showed to be off the central axis of the capture section in the baseline configuration. The off-centred interaction region resulted in ...

  10. US Spacesuit Knowledge Capture

    Science.gov (United States)

    Chullen, Cinda; Thomas, Ken; McMann, Joe; Dolan, Kristi; Bitterly, Rose; Lewis, Cathleen

    2011-01-01

    The ability to learn from both the mistakes and successes of the past is vital to assuring success in the future. Due to the close physical interaction between spacesuit systems and human beings as users, spacesuit technology and usage lends itself rather uniquely to the benefits realized from the skillful organization of historical information; its dissemination; the collection and identification of artifacts; and the education of those in the field. The National Aeronautics and Space Administration (NASA), other organizations and individuals have been performing United States (U.S.) Spacesuit Knowledge Capture since the beginning of space exploration. Avenues used to capture the knowledge have included publication of reports; conference presentations; specialized seminars; and classes usually given by veterans in the field. More recently the effort has been more concentrated and formalized whereby a new avenue of spacesuit knowledge capture has been added to the archives in which videotaping occurs engaging both current and retired specialists in the field presenting technical scope specifically for education and preservation of knowledge. With video archiving, all these avenues of learning can now be brought to life with the real experts presenting their wealth of knowledge on screen for future learners to enjoy. Scope and topics of U.S. spacesuit knowledge capture have included lessons learned in spacesuit technology, experience from the Gemini, Apollo, Skylab and Shuttle programs, hardware certification, design, development and other program components, spacesuit evolution and experience, failure analysis and resolution, and aspects of program management. Concurrently, U.S. spacesuit knowledge capture activities have progressed to a level where NASA, the National Air and Space Museum (NASM), Hamilton Sundstrand (HS) and the spacesuit community are now working together to provide a comprehensive closed-looped spacesuit knowledge capture system which includes

  11. Motion Capturing Emotions

    OpenAIRE

    Wood Karen; Cisneros Rosemary E.; Whatley Sarah

    2017-01-01

    The paper explores the activities conducted as part of WhoLoDancE: Whole Body Interaction Learning for Dance Education which is an EU-funded Horizon 2020 project. In particular, we discuss the motion capture sessions that took place at Motek, Amsterdam as well as the dancers’ experience of being captured and watching themselves or others as varying visual representations through the HoloLens. HoloLens is Microsoft’s first holographic computer that you wear as you would a pair of glasses. The ...

  12. Nuclear muon capture

    CERN Document Server

    Mukhopadhyay, N C

    1977-01-01

    Our present knowledge of the nuclear muon capture reactions is surveyed. Starting from the formation of the muonic atom, various phenomena, having a bearing on the nuclear capture, are reviewed. The nuclear reactions are then studied from two angles-to learn about the basic muon+nucleon weak interaction process, and to obtain new insights on the nuclear dynamics. Future experimental prospects with the newer generation muon 'factories' are critically examined. Possible modification of the muon+nucleon weak interaction in complex nuclei remains the most important open problem in this field. (380 refs).

  13. Hospital-based proton linear accelerator for particle therapy and radioisotope production

    Science.gov (United States)

    Lennox, Arlene J.

    1991-05-01

    Taking advantage of recent advances in linear accelerator technology, it is possible for a hospital to use a 70 MeV proton linac for fast neutron therapy, boron neutron capture therapy, proton therapy for ocular melanomas, and production of radiopharmaceuticals. The linac can also inject protons into a synchrotron for proton therapy of deep-seated tumors. With 180 μA average current, a single linac can support all these applications. This paper presents a conceptual design for a medical proton linac, switchyard, treatment rooms, and isotope production rooms. Special requirements for each application are outlined and a layout for sharing beam among the applications is suggested.

  14. Proton-Proton and Proton-Antiproton Colliders

    CERN Document Server

    Scandale, Walter

    2014-01-01

    In the last five decades, proton–proton and proton–antiproton colliders have been the most powerful tools for high energy physics investigations. They have also deeply catalyzed innovation in accelerator physics and technology. Among the large number of proposed colliders, only four have really succeeded in becoming operational: the ISR, the SppbarS, the Tevatron and the LHC. Another hadron collider, RHIC, originally conceived for ion–ion collisions, has also been operated part-time with polarized protons. Although a vast literature documenting them is available, this paper is intended to provide a quick synthesis of their main features and key performance.

  15. Three-Dimensional General-Relativistic Magnetohydrodynamic Simulations of Remnant Accretion Disks from Neutron Star Mergers: Outflows and r-Process Nucleosynthesis.

    Science.gov (United States)

    Siegel, Daniel M; Metzger, Brian D

    2017-12-08

    The merger of binary neutron stars, or of a neutron star and a stellar-mass black hole, can result in the formation of a massive rotating torus around a spinning black hole. In addition to providing collimating media for γ-ray burst jets, unbound outflows from these disks are an important source of mass ejection and rapid neutron capture (r-process) nucleosynthesis. We present the first three-dimensional general-relativistic magnetohydrodynamic (GRMHD) simulations of neutrino-cooled accretion disks in neutron star mergers, including a realistic equation of state valid at low densities and temperatures, self-consistent evolution of the electron fraction, and neutrino cooling through an approximate leakage scheme. After initial magnetic field amplification by magnetic winding, we witness the vigorous onset of turbulence driven by the magnetorotational instability (MRI). The disk quickly reaches a balance between heating from MRI-driven turbulence and neutrino cooling, which regulates the midplane electron fraction to a low equilibrium value Y_{e}≈0.1. Over the 380-ms duration of the simulation, we find that a fraction ≈20% of the initial torus mass is unbound in powerful outflows with asymptotic velocities v≈0.1c and electron fractions Y_{e}≈0.1-0.25. Postprocessing the outflows through a nuclear reaction network shows the production of a robust second- and third-peak r process. Though broadly consistent with the results of previous axisymmetric hydrodynamical simulations, extrapolation of our results to late times suggests that the total ejecta mass from GRMHD disks is significantly higher. Our results provide strong evidence that postmerger disk outflows are an important site for the r process.

  16. METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS

    Energy Technology Data Exchange (ETDEWEB)

    Placco, Vinicius M.; Rossi, Silvia [Departamento de Astronomia-Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Sao Paulo, SP 05508-900 (Brazil); Frebel, Anna [Massachusetts Institute of Technology and Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Beers, Timothy C. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Karakas, Amanda I.; Kennedy, Catherine R. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Christlieb, Norbert [Zentrum fuer Astronomie der Universitaet Heidelberg, Landessternwarte, Koenigstuhl 12, D-69117 Heidelberg (Germany); Stancliffe, Richard J. [Argelander-Institut fuer Astronomie der Universitaet Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany)

    2013-06-20

    We present a comprehensive abundance analysis of two newly discovered carbon-enhanced metal-poor (CEMP) stars. HE 2138-3336 is a s-process-rich star with [Fe/H] = -2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if non-local thermodynamic equilibrium corrections are included ([Pb/Fe] = +3.84). HE 2258-6358, with [Fe/H] = -2.67, exhibits enrichments in both s- and r-process elements. These stars were selected from a sample of candidate metal-poor stars from the Hamburg/ESO objective-prism survey, and followed up with medium-resolution (R {approx} 2000) spectroscopy with GEMINI/GMOS. We report here on derived abundances (or limits) for a total of 34 elements in each star, based on high-resolution (R {approx} 30, 000) spectroscopy obtained with Magellan-Clay/MIKE. Our results are compared to predictions from new theoretical asymptotic giant branch (AGB) nucleosynthesis models of 1.3 M{sub Sun} with [Fe/H] = -2.5 and -2.8, as well as to a set of AGB models of 1.0 to 6.0 M{sub Sun} at [Fe/H] = -2.3. The agreement with the model predictions suggests that the neutron-capture material in HE 2138-3336 originated from mass transfer from a binary companion star that previously went through the AGB phase, whereas for HE 2258-6358, an additional process has to be taken into account to explain its abundance pattern. We find that a narrow range of progenitor masses (1.0 {<=} M(M{sub Sun }) {<=} 1.3) and metallicities (-2.8 {<=} [Fe/H] {<=}-2.5) yield the best agreement with our observed elemental abundance patterns.

  17. Deep-Ocean Crusts as Telescopes: Using Live Radioisotopes to Probe Supernova Nucleosynthesis

    CERN Document Server

    Fields, B D; Ellis, Jonathan Richard; Fields, Brian D.; Hochmuth, Kathrin A.; Ellis, John

    2005-01-01

    Live 60Fe has recently been detected in a deep-ocean ferromanganese crust, isolated in layers dating from about 3 Myr ago. Since 60Fe has a mean life of 2.2 Myr, a near-Earth supernova is the only likely source for such a signal, and we explore here the consequences of a supernova origin. We combine the 60Fe data with several supernova nucleosynthesis models to calculate the supernova distance as a function of progenitor mass, finding an allowed range of 15-120 pc. We also predict the signals expected for several other radioisotopes, which are independent of the supernova distance. Species likely to be present near or above background levels are 10Be, 26Al, 53Mn, 182Hf and 244Pu. Of these, 182Hf and 244Pu are nearly background-free, presenting the best opportunities to provide strong confirmation of the supernova origin of the 60Fe signal, and to demonstrate that at least some supernovae are the source for the r-process. The accuracies of our predictions are hampered by large uncertainties in the predicted 60...

  18. Concordance of X-ray cluster data with big bang nucleosynthesis in mixed dark matter models

    International Nuclear Information System (INIS)

    Strickland, R.W.; Schramm, D.N.

    1997-01-01

    If the hot, X-ray-emitting gas in rich clusters forms a fair sample of the universe as in cold dark matter (CDM) models and the universe is at the critical density Ω T =1, then the data appear to imply a baryon fraction Ω b,X (Ω b,X ≡Ω b derived from X-ray cluster data), larger than that predicted by big bang nucleosynthesis (BBN). While other systematic effects such as clumping can lower Ω b,X , in this paper we use an elementary analysis to show that a simple admixture of hot dark matter (HDM; low-mass neutrinos) with CDM to yield mixed dark matter shifts Ω b,X down so that significant overlap with Ω b from BBN can occur for H 0 approx-lt 73kms -1 Mpc -1 , even without invoking the possible aforementioned effects. The overlap interval is slightly larger for lower mass neutrinos since fewer of them cluster on the scale of the hot X-ray gas. We illustrate this result quantitatively in terms of a simple isothermal model. More realistic velocity dispersion profiles, with less centrally peaked density profiles, imply that fewer neutrinos are trapped and thus further increase the interval of overlap. copyright 1997 The American Astronomical Society

  19. General neutralino NLSP with gravitino dark matter vs. big bang nucleosynthesis

    International Nuclear Information System (INIS)

    Hasenkamp, Jasper

    2009-08-01

    We study the scenario of gravitino dark matter with a general neutralino being the next-to-lightest supersymmetric particle (NLSP). Therefore, we compute analytically all 2- and 3-body decays of the neutralino NLSP to determine the lifetime and the electromagnetic and hadronic branching ratio of the neutralino decaying into the gravitino and Standard Model particles. We constrain the gravitino and neutralino NLSP mass via big bang nucleosynthesis and see how those bounds are relaxed for a Higgsino or a wino NLSP in comparison to the bino neutralino case. At neutralino masses >or similar 1 TeV, a wino NLSP is favoured, since it decays rapidly via a newly found 4-vertex. The Higgsino component becomes important, when resonant annihilation via heavy Higgses can occur. We provide the full analytic results for the decay widths and the complete set of Feynman rules necessary for these computations. This thesis closes any gap in the study of gravitino dark matter scenarios with neutralino NLSP coming from approximations in the calculation of the neutralino decay rates and its hadronic branching ratio. (orig.)

  20. Constraining strong baryon-dark-matter interactions with primordial nucleosynthesis and cosmic rays

    International Nuclear Information System (INIS)

    Cyburt, Richard H.; Fields, Brian D.; Pavlidou, Vasiliki; Wandelt, Benjamin

    2002-01-01

    Self-interacting dark matter (SIDM) was introduced by Spergel and Steinhardt to address possible discrepancies between collisionless dark matter simulations and observations on scales of less than 1 Mpc. We examine the case in which dark matter particles not only have strong self-interactions but also have strong interactions with baryons. The presence of such interactions will have direct implications for nuclear and particle astrophysics. Among these are a change in the predicted abundances from big bang nucleosynthesis (BBN) and the flux of γ rays produced by the decay of neutral pions which originate in collisions between dark matter and galactic cosmic rays (CR). From these effects we constrain the strength of the baryon-dark-matter interactions through the ratio of baryon-dark-matter interaction cross section to dark matter mass, s. We find that BBN places a weak upper limit on this ratio (less-or-similar sign)10 8 cm 2 g -1 . CR-SIDM interactions, however, limit the possible DM-baryon cross section to (less-or-similar sign)5x10 -3 cm 2 g -1 ; this rules out an energy-independent interaction, but not one which falls with center-of-mass velocity s∝1/v or steeper

  1. General neutralino NLSP with gravitino dark matter vs. big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hasenkamp, Jasper

    2009-08-15

    We study the scenario of gravitino dark matter with a general neutralino being the next-to-lightest supersymmetric particle (NLSP). Therefore, we compute analytically all 2- and 3-body decays of the neutralino NLSP to determine the lifetime and the electromagnetic and hadronic branching ratio of the neutralino decaying into the gravitino and Standard Model particles. We constrain the gravitino and neutralino NLSP mass via big bang nucleosynthesis and see how those bounds are relaxed for a Higgsino or a wino NLSP in comparison to the bino neutralino case. At neutralino masses >or similar 1 TeV, a wino NLSP is favoured, since it decays rapidly via a newly found 4-vertex. The Higgsino component becomes important, when resonant annihilation via heavy Higgses can occur. We provide the full analytic results for the decay widths and the complete set of Feynman rules necessary for these computations. This thesis closes any gap in the study of gravitino dark matter scenarios with neutralino NLSP coming from approximations in the calculation of the neutralino decay rates and its hadronic branching ratio. (orig.)

  2. Lithium in Very Metal-poor Dwarf Stars -- Problems for Standard Big Bang Nucleosynthesis?

    International Nuclear Information System (INIS)

    Lambert, David L.

    2004-01-01

    The standard model of primordial nucleosynthesis by the Big Bang as selected by the WMAP-based estimate of the baryon density (Ωbh2) predicts an abundance of 7Li that is a factor of three greater than the generally reported abundance for stars on the Spite plateau, and an abundance of 6Li that is about a thousand times less than is found for some stars on the plateau. This review discusses and examines these two discrepancies. They can likely be resolved without major surgery on the standard model of the Big Bang. In particular, stars on the Spite plateau may have depleted their surface lithium abundance over their long lifetime from the WMAP-based predicted abundances down to presently observed abundances, and synthesis of 6Li (and 7Li) via α + α fusion reactions may have occurred in the early Galaxy. Yet, there remain fascinating ways in which to remove the two discrepancies involving aspects of a new cosmology, particularly through the introduction of exotic particles

  3. Effects of sterile neutrinos and an extra dimension on big bang nucleosynthesis

    Science.gov (United States)

    Jang, Dukjae; Kusakabe, Motohiko; Cheoun, Myung-Ki

    2018-02-01

    By assuming the existence of extra-dimensional sterile neutrinos in the big bang nucleosynthesis (BBN) epoch, we investigate the sterile neutrino (νs) effects on the BBN and constrain some parameters associated with the νs properties. First, for the cosmic expansion rate, we take into account effects of a five-dimensional bulk and intrinsic tension of the brane embedded in the bulk and constrain a key parameter of the extra dimension by using the observational element abundances. Second, effects of the νs traveling on or off the brane are considered. In this model, the effective mixing angle between a νs and an active neutrino depends on energy, which may give rise to a resonance effect on the mixing angle. Consequently, the reaction rate of the νs can be drastically changed during the cosmic evolution. We estimated abundances and temperature of the νs by solving the rate equation as a function of temperature until the sterile neutrino decoupling. We then find that the relic abundance of the νs is drastically enhanced by the extra dimension and maximized for a characteristic resonance energy Eres≳0.01 GeV . Finally, some constraints related to the νs, i.e., mixing angle and mass difference, are discussed in detail with the comparison of our BBN calculations corrected by the extra-dimensional νs to observational data on light element abundances.

  4. AMS. A powerful tool for probing nucleosynthesis via long-lived radionuclides

    International Nuclear Information System (INIS)

    Wallner, A.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.; Kaeppeler, F.

    2005-01-01

    The potential of accelerator mass spectrometry (AMS) will be demonstrated on typical radionuclides of interest with half-lives between some years and up to hundred million years. The Vienna Environmental Research Accelerator (VERA) represents a state-of-the-art AMS facility which provides the ability for quantifying nuclides over the whole mass range. At VERA, AMS is used for quantifying long-lived radionuclides within a wide range of applications - from archaeology to astrophysics. Lack of information on cross section data exists for a list of nuclides pointed out by nuclear data requests. The potential of AMS as a powerful tool for probing nucleosynthesis will be demonstrated by means of some prime examples. Recent developments in the technique of AMS will be highlighted and some applications of AMS in astrophysics will be discussed. In addition, an overview on detection limits, measurement precision as well as the recent measurement program at VERA for quantifying such long-lived radionuclides will be presented. (author)

  5. Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Jedamzik, Karsten, E-mail: jedamzik@lpta.univ-montp2.fr [Laboratoire de Physique Mathémathique et Théorique, CNRS, Université de Montpellier II, F-34095 Montpellier Cedex 5 (France)

    2008-03-01

    The Big Bang nucleosynthesis (BBN) process in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of {sup 6}Li and {sup 7}Li, are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3×10{sup 2} s∼<τ{sub x}∼<10{sup 12} s. It is stressed that the production of {sup 6}Li at early times T∼10 keV is overestimated by a factor ∼10 when the approximation of the Saha equation for the {sup 4}He bound state fraction is utilized. To obtain conservative limits on the abundance of CHAMPs, a Monte Carlo analysis with ∼3 × 10{sup 6} independent BBN runs, varying the reaction rates of 19 different reactions, is performed. The analysis yields the surprising result that, except for small areas in the particle parameter space, conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in the case that the rates of a number of heretofore unconsidered reactions may be determined reliably in the future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude.

  6. Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

    Science.gov (United States)

    Jedamzik, Karsten

    2008-03-01

    The Big Bang nucleosynthesis (BBN) process in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of 6Li and 7Li, are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3\\times 10^2~\\mathrm {s}\\lesssim \\tau_x\\lesssim 10^{12}~\\mathrm {s} . It is stressed that the production of 6Li at early times T~10 keV is overestimated by a factor ~10 when the approximation of the Saha equation for the 4He bound state fraction is utilized. To obtain conservative limits on the abundance of CHAMPs, a Monte Carlo analysis with ~3 × 106 independent BBN runs, varying the reaction rates of 19 different reactions, is performed. The analysis yields the surprising result that, except for small areas in the particle parameter space, conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in the case that the rates of a number of heretofore unconsidered reactions may be determined reliably in the future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude.

  7. Muon capture in deuterium

    Czech Academy of Sciences Publication Activity Database

    Ricci, P.; Truhlík, Emil; Mosconi, B.; Smejkal, J.

    2010-01-01

    Roč. 837, - (2010), s. 110-144 ISSN 0375-9474 Institutional research plan: CEZ:AV0Z10480505 Keywords : Negative muon capture * Deuteron * Potential models Subject RIV: BE - Theoretical Physics Impact factor: 1.986, year: 2010

  8. Capture Matrices Handbook

    Science.gov (United States)

    2014-04-01

    materials, the affinity ligand would need identification , as well as chemistries that graft the affinity ligand onto the surface of magnetic...ACTIVE CAPTURE MATRICES FOR THE DETECTION/ IDENTIFICATION OF PHARMACEUTICALS...6 As shown in Figure 2.3-1a, the spectra exhibit similar baselines and the spectral peaks lineup . Under these circumstances, the spectral

  9. Capacitance for carbon capture

    International Nuclear Information System (INIS)

    Landskron, Kai

    2018-01-01

    Metal recycling: A sustainable, capacitance-assisted carbon capture and sequestration method (Supercapacitive Swing Adsorption) can turn scrap metal and CO 2 into metal carbonates at an attractive energy cost. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Capacitance for carbon capture

    Energy Technology Data Exchange (ETDEWEB)

    Landskron, Kai [Department of Chemistry, Lehigh University, Bethlehem, PA (United States)

    2018-03-26

    Metal recycling: A sustainable, capacitance-assisted carbon capture and sequestration method (Supercapacitive Swing Adsorption) can turn scrap metal and CO{sub 2} into metal carbonates at an attractive energy cost. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Embedded enzymes catalyse capture

    Science.gov (United States)

    Kentish, Sandra

    2018-05-01

    Membrane technologies for carbon capture can offer economic and environmental advantages over conventional amine-based absorption, but can suffer from limited gas flux and selectivity to CO2. Now, a membrane based on enzymes embedded in hydrophilic pores is shown to exhibit combined flux and selectivity that challenges the state of the art.

  12. Attention Capture by Faces

    Science.gov (United States)

    Langton, Stephen R. H.; Law, Anna S.; Burton, A. Mike; Schweinberger, Stefan R.

    2008-01-01

    We report three experiments that investigate whether faces are capable of capturing attention when in competition with other non-face objects. In Experiment 1a participants took longer to decide that an array of objects contained a butterfly target when a face appeared as one of the distracting items than when the face did not appear in the array.…

  13. Super-AGB Stars and their Role as Electron Capture Supernova Progenitors

    Science.gov (United States)

    Doherty, Carolyn L.; Gil-Pons, Pilar; Siess, Lionel; Lattanzio, John C.

    2017-11-01

    We review the lives, deaths and nucleosynthetic signatures of intermediate-mass stars in the range ≈6-12 M⊙, which form super-AGB stars near the end of their lives. The critical mass boundaries both between different types of massive white dwarfs (CO, CO-Ne, ONe), and between white dwarfs and supernovae, are examined along with the relative fraction of super-AGB stars that end life either as an ONe white dwarf or as a neutron star (or an ONeFe white dwarf), after undergoing an electron capture supernova event. The contribution of the other potential single-star channel to electron-capture supernovae, that of the failed massive stars, is also discussed. The factors that influence these different final fates and mass limits, such as composition, rotation, the efficiency of convection, the nuclear reaction rates, mass-loss rates, and third dredge-up efficiency, are described. We stress the importance of the binary evolution channels for producing electron-capture supernovae. Recent nucleosynthesis calculations and elemental yield results are discussed and a new set of s-process heavy element yields is presented. The contribution of super-AGB star nucleosynthesis is assessed within a Galactic perspective, and the (super-)AGB scenario is considered in the context of the multiple stellar populations seen in globular clusters. A brief summary of recent works on dust production is included. Last, we conclude with a discussion of the observational constraints and potential future advances for study into these stars on the low mass/high mass star boundary.

  14. Proton storage ring summer workshop

    International Nuclear Information System (INIS)

    Lawrence, G.P.; Cooper, R.K.

    1977-10-01

    During the week of August 16, 1976 a Workshop was held at the Los Alamos Scientific Laboratory (LASL) on the Proton Storage Ring (PSR) for the Weapons Neutron Research Facility (WNRF). Written contributions were solicited from each of the participants in the Workshop, and the contributions that were received are presented. The papers do not represent polished or necessarily complete work, but rather represent ''first cuts'' at their respective areas. Topics covered include: (1) background information on the storage ring; (2) WNRF design; (3) rf transient during filling; (4) rf capture; (5) beam bunch compression; (6) transverse space charge limits; (7) transverse resistive instability in the PSR; (8) longitudinal resistive instability; (9) synchrotron frequency splitting; (10) E Quintus Unum--off resonance; (11) first harmonic bunching in the storage ring; (12) kicker considerations; (13) beam extraction; (14) ferrite kicker magnets; and (15) E Quintus Unum: a possible ejection scheme

  15. Proton Fast Ignition

    International Nuclear Information System (INIS)

    Key, M H; Freeman, R R; Hatchett, S P; MacKinnon, A J; Patel, P K; Snavely, R A; Stephens, R B

    2006-04-01

    Fast ignition (FI) by a laser generated ballistically focused proton beam is a more recently proposed alternative to the original concept of FI by a laser generated beam of relativistic electrons. It has potential advantages in less complex energy transport into dense plasma. Recent successful target heating experiments motivate further investigation of the feasibility of proton fast ignition. The concept, the physics and characteristics of the proton beams, the recent experimental work on focusing of the beams and heating of solid targets and the overall prospects for proton FI are discussed

  16. Proton decay: spectroscopic probe beyond the proton drip line

    International Nuclear Information System (INIS)

    Seweryniak, D; Davids, C N; Robinson, A; Woods, P J; Blank, B; Carpenter, M P; Davinson, T; Freeman, S J; Hammond, N; Hoteling, N; Janssens, R V F; Khoo, T L; Liu, Z; Mukherjee, G; Shergur, J; Sinha, S; Sonzogni, A A; Walters, W B; Woehr, A

    2005-01-01

    Proton decay has been transformed in recent years from an exotic phenomenon into a powerful spectroscopic tool. The frontiers of experimental and theoretical proton-decay studies will be reviewed. Different aspects of proton decay will be illustrated with recent results on the deformed proton emitter 135 Tb, the odd-odd deformed proton emitter 130 Eu, the complex fine structure in the odd-odd 146 Tm nucleus and on excited states in the transitional proton emitter 145 Tm

  17. Review of inelastic proton-proton reactions

    CERN Document Server

    Morrison, Douglas Robert Ogston

    1973-01-01

    The most important new results on inelastic proton-proton scattering obtained with the new machines, I.S.R. and N.A.L., are: (1) The inelastic cross-section increases monotonically with energy from threshold to 1500 GeV/c. Above 6 GeV/c the energy variation has a s /sup +0.04/ behaviour. (2) Scaling is observed at I.S.R. energies in pion production. Confirmation is obtained of the hypothesis of limiting fragmentation. (3) The results are in general, consistent with the two-component model-one class of events being produced by diffraction dissociation and the other by a short-range-order process (e.g. the multiperipheral model). (4) There are indications that the protons have a granular structure; this from observation of secondaries of large transverse momenta. (33 refs).

  18. Gadolinium neutron capture therapy

    International Nuclear Information System (INIS)

    Akine, Yasuyuki; Tokita, Nobuhiko; Tokuuye, Koichi; Satoh, Michinao; Churei, Hisahiko

    1993-01-01

    Gadolinium neutron capture therapy makes use of photons and electrons produced by nuclear reactions between gadolinium and lower-energy neutrons which occur within the tumor. The results of our studies have shown that its radiation effect is mostly of low LET and that the electrons are the significant component in the over-all dose. The dose from gadolinium neutron capture reactions does not seem to increase in proportion to the gadolinium concentration, and the Gd-157 concentration of about 100 μg/ml appears most optimal for therapy. Close contact between gadolinium and the cell is not necessarily required for cell inactivation, however, the effect of electrons released from intracellular gadolinium may be significant. Experimental studies on tumor-bearing mice and rabbits have shown that this is a very promising modality though further improvements in gadolinium delivery to tumors are needed. (author)

  19. Protons and how they are transported by proton pumps

    DEFF Research Database (Denmark)

    Buch-Pedersen, Morten Jeppe; Pedersen, Bjørn Panyella; Nissen, Poul

    2008-01-01

    molecular components that allow the plasma membrane proton H(+)-ATPase to carry out proton transport against large membrane potentials. When divergent proton pumps such as the plasma membrane H(+)-ATPase, bacteriorhodopsin, and F(O)F(1) ATP synthase are compared, unifying mechanistic premises for biological...... proton pumps emerge. Most notably, the minimal pumping apparatus of all pumps consists of a central proton acceptor/donor, a positively charged residue to control pK (a) changes of the proton acceptor/donor, and bound water molecules to facilitate rapid proton transport along proton wires....

  20. Giving Protons a Boost

    CERN Multimedia

    2004-01-01

    The first of LHC's superconducting radio-frequency cavity modules has passed its final test at full power in the test area of building SM18. These modules carry an oscillating electric field that will accelerate protons around the LHC ring and help maintain the stability of the proton beams.

  1. On the proton decay

    International Nuclear Information System (INIS)

    Fonda, L.; Ghirardi, G.C.; Weber, T.

    1983-07-01

    The problem of the proton decay is considered taking into account that in actual experiments there is an interaction of the proton with its environment which could imply an increase of its theoretical lifetime. It is seen that, by application of the time-energy uncertainty relation, no prolongation of the lifetime is obtained in this case. (author)

  2. Neutron emission study after muon capture by nuclei

    International Nuclear Information System (INIS)

    Bouyssy, Alain.

    1974-01-01

    Muon capture by nuclei, used in the beginning for checking the weak interaction, is now a method of investigation of nuclear structure. Study of spectrum, asymmetry and polarization of emitted neutrons after polarized muon capture has been done in three directions: weak coupling constants, final state interaction, nuclear wave functions. The neutron intensity and helicity are very dependent of the neutron - residual nucleus interaction, while the asymmetry is sensitive to the wave functions used for the proton. Moreover if the induced tensor coupling constant is different from zero the asymmetry is increased. Longitudinal polarization experiments, with those for neutron intensity, would be of great interest to give informations on neutron asymmetry [fr

  3. Theory of Quasi-Equilibrium Nucleosynthesis and Applications to Matter Expanding from High Temperature and Density

    Science.gov (United States)

    Meyer, Bradley S.; Krishnan, Tracy D.; Clayton, Donald D.

    1998-05-01

    Our first purpose is construction of a formal theory of quasi-equilibrium. We define quasi-equilibrium, in its simplest form, as statistical equilibrium in the face of an extra constraint on the nuclear populations. We show that the extra constraint introduces a uniform translation of the chemical potentials for the heavy nuclei and derive the abundances in terms of it. We then generalize this theory to accommodate any number of constraints. For nucleosynthesis, the most important constraint occurs when the total number of heavy nuclei Yh within a system of nuclei differs from the number that would exist in nuclear statistical equilibrium (NSE) under the same conditions of density and temperature. Three situations of high relevance are (1) silicon burning, wherein the total number of nuclei exceeds but asymptotically approaches the NSE number; (2) alpha-rich freezeout expansions of high entropy, wherein Yh is less than the NSE number; and (3) expansions from high temperature of low-entropy matter, in which Yh exceeds the NSE number. These are of importance, respectively, within (1) supernova shells, (2) Type II supernova cores modestly outside the mass cut, and (3) Type Ia supernova cores in near-Chandrasekhar-mass events. Our next goal is the detailed analysis of situation (2), the high-entropy alpha-rich neutron-rich freezeout. We employ a nuclear reaction network, which we integrate, to compare the actual abundances with those obtained at the same thermal conditions by the quasi-equilibrium (QSE) theory and by the NSE theory. For this detailed comparison, we choose a high-entropy photon-to-nucleon ratio φ = 6.8, for which we conduct expansions at initial bulk neutron excess η0 = 0.10. We demonstrate that the abundance populations, as they begin expansion and cooling from temperature 10 × 109 K, are characterized by three distinct phases: (1) NSE, (2) QSE having Yh smaller than the NSE value, and (3) final reaction rate-dependent freezeout modifications of the

  4. PS proton source

    CERN Multimedia

    1959-01-01

    The first proton source used at CERN's Proton Synchrotron (PS) which started operation in 1959. This is CERN's oldest accelerator still functioning today (2018). It is part of the accelerator chain that supplies proton beams to the Large Hadron Collider. The source is a Thonemann type. In order to extract and accelerate the protons at high energy, a high frequency electrical field is used (140Mhz). The field is transmitted by a coil around a discharge tube in order to maintain the gas hydrogen in an ionised state. An electrical field pulse, in the order of 15kV, is then applied via an impulse transformer between anode and cathode of the discharge tube. The electrons and protons of the plasma formed in the ionised gas in the tube, are then separated. Currents in the order of 200mA during 100 microseconds have benn obtained with this type of source.

  5. Pygmy and core polarization dipole modes in 206Pb: Connecting nuclear structure to stellar nucleosynthesis

    Science.gov (United States)

    Tonchev, A. P.; Tsoneva, N.; Bhatia, C.; Arnold, C. W.; Goriely, S.; Hammond, S. L.; Kelley, J. H.; Kwan, E.; Lenske, H.; Piekarewicz, J.; Raut, R.; Rusev, G.; Shizuma, T.; Tornow, W.

    2017-10-01

    A high-resolution study of the electromagnetic response of 206Pb below the neutron separation energy is performed using a (γ → ,γ‧) experiment at the HI γ → S facility. Nuclear resonance fluorescence with 100% linearly polarized photon beams is used to measure spins, parities, branching ratios, and decay widths of excited states in 206Pb from 4.9 to 8.1 MeV. The extracted ΣB (E 1) ↑ and ΣB (M 1) ↑ values for the total electric and magnetic dipole strength below the neutron separation energy are 0.9 ± 0.2 e2fm2 and 8.3 ± 2.0 μN2, respectively. These measurements are found to be in very good agreement with the predictions from an energy-density functional (EDF) plus quasiparticle phonon model (QPM). Such a detailed theoretical analysis allows to separate the pygmy dipole resonance from both the tail of the giant dipole resonance and multi-phonon excitations. Combined with earlier photonuclear experiments above the neutron separation energy, one extracts a value for the electric dipole polarizability of 206Pb of αD = 122 ± 10 mb /MeV. When compared to predictions from both the EDF+QPM and accurately calibrated relativistic EDFs, one deduces a range for the neutron-skin thickness of Rskin206 = 0.12- 0.19 fm and a corresponding range for the slope of the symmetry energy of L = 48- 60 MeV. This newly obtained information is also used to estimate the Maxwellian-averaged radiative cross section 205Pb (n , γ)206Pb at 30 keV to be σ = 130 ± 25 mb. The astrophysical impact of this measurement-on both the s-process in stellar nucleosynthesis and on the equation of state of neutron-rich matter-is discussed.

  6. An update on the big bang nucleosynthesis prediction for 7Li: the problem worsens

    International Nuclear Information System (INIS)

    Cyburt, Richard H; Fields, Brian D; Olive, Keith A

    2008-01-01

    The lithium problem arises from the significant discrepancy between the primordial 7 Li abundance as predicted by big bang nucleosynthesis (BBN) theory and the Wilkinson Microwave Anisotropy Probe (WMAP) baryon density, and the pre-Galactic lithium abundance inferred from observations of metal-poor (Population II) stars. This problem has loomed for the past decade, with a persistent discrepancy of a factor of 2–3 in 7 Li/H. Recent developments have sharpened all aspects of the Li problem. Namely: (1) BBN theory predictions have sharpened due to new nuclear data; in particular, the uncertainty on the reaction rate for 3 He(α,γ) 7 Be has reduced to 7.4%, nearly a factor of 2 tighter than previous determinations. (2) The WMAP five-year data set now yields a cosmic baryon density with an uncertainty reduced to 2.7%. (3) Observations of metal-poor stars have tested for systematic effects. With these, we now find that the BBN+WMAP predicts 7 Li/H = (5.24 −0.67 +0.71 ) × 10 −10 . The central value represents an increase by 23%, most of which is due to the upward shift in the 3 He(α,γ) 7 Be rate. More significant is the reduction in the 7 Li/H uncertainty by almost a factor of 2, tracking the reduction in the 3 He(α,γ) 7 Be error bar. These changes exacerbate the Li problem; the discrepancy is now a factor 2.4 or 4.2σ (from globular cluster stars) to 4.3 or 5.3σ (from halo field stars). Possible resolutions to the lithium problem are briefly reviewed, and key experimental and astronomical measurements highlighted

  7. Advancing nucleosynthesis in self-consistent, multidimensional models of core-collapse supernovae

    International Nuclear Information System (INIS)

    Austin Harris, J.; Chertkow, M.A.; Blondin, J.M.; Pedro Marronetti; Florida Atlantic University, Boca Raton, FL

    2014-01-01

    We investigate CCSN in polar axisymmetric simulations using the multidimensional radiation hydrodynamics code CHIMERA. Computational costs have traditionally constrained the evolution of the nuclear composition in CCSN models to, at best, a 14-species α-network. However, the limited capacity of the α-network to accurately evolve detailed composition, the neutronization and the nuclear energy generation rate has fettered the ability of prior CCSN simulations to accurately reproduce the chemical abundances and energy distributions as known from observations. These deficits can be partially ameliorated by 'post-processing' with a more realistic network. Lagrangian tracer particles placed throughout the star record the temporal evolution of the initial simulation and enable the extension of the nuclear network evolution by incorporating larger systems in post-processing nucleosynthesis calculations. We present post-processing results of four ab initio axisymmetric CCSN 2D models evolved with the smaller α-network, and initiated from stellar metallicity, nonrotating progenitors of mass 12, 15, 20, and 25 M ⊙ 2 . As a test of the limitations of postprocessing, we provide preliminary results from an ongoing simulation of the 15 M ⊙ model evolved with a realistic 150 species nuclear reaction network in situ. With more accurate energy generation rates and an improved determination of the thermodynamic trajectories of the tracer particles, we can better unravel the complicated multidimensional 'mass-cut' in CCSN simulations and probe for less energetically significant nuclear processes like the νp-process and the r-process, which require still larger networks. (author)

  8. Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

    International Nuclear Information System (INIS)

    Mangano, Gianpiero; Miele, Gennaro; Pisanti, Ofelia; Sarikas, Srdjan; Pastor, Sergio

    2011-01-01

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N eff . This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N eff from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, η ν = η ν e +η ν μ +η ν τ and the initial electron neutrino asymmetry η ν e in , solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the ν e −ν-bar e asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2 H/H density ratio and 4 He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2 H/H abundance plays a relevant role in constraining the allowed regions in the η ν −η ν e in plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N eff as a function of the mixing parameter θ 13 , and point out the upper bound N eff ∼ eff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe

  9. Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

    Science.gov (United States)

    Mangano, Gianpiero; Miele, Gennaro; Pastor, Sergio; Pisanti, Ofelia; Sarikas, Srdjan

    2011-03-01

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos Neff. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on Neff from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, ην = ηνe+ηνμ+ηντ and the initial electron neutrino asymmetry ηνein, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the νe-bar nue asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2H/H density ratio and 4He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2H/H abundance plays a relevant role in constraining the allowed regions in the ην-ηνein plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to Neff as a function of the mixing parameter θ13, and point out the upper bound Nefflesssim3.4. Comparing these results with the forthcoming measurement of Neff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.

  10. Using Big Bang Nucleosynthesis to extend CMB probes of neutrino physics

    Energy Technology Data Exchange (ETDEWEB)

    Shimon, M.; Miller, N.J.; Fuller, G.M.; Keating, B.G. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA, 92093 (United States); Kishimoto, C.T. [Department of Physics and Astronomy, University of California, Los Angeles, CA, 90095 (United States); Smith, C.J., E-mail: meirs@mamacass.ucsd.edu, E-mail: nmiller@physics.ucsd.edu, E-mail: ckishimo@physics.ucsd.edu, E-mail: christel.smith@asu.edu, E-mail: gfuller@ucsd.edu, E-mail: bkeating@ucsd.edu [Department of Physics, Arizona State University, Tempe, AZ, 85287 (United States)

    2010-05-01

    We present calculations showing that upcoming Cosmic Microwave Background (CMB) experiments will have the power to improve on current constraints on neutrino masses and provide new limits on neutrino degeneracy parameters. The latter could surpass those derived from Big Bang Nucleosynthesis (BBN) and the observationally-inferred primordial helium abundance. These conclusions derive from our Monte Carlo Markov Chain (MCMC) simulations which incorporate a full BBN nuclear reaction network. This provides a self-consistent treatment of the helium abundance, the baryon number, the three individual neutrino degeneracy parameters and other cosmological parameters. Our analysis focuses on the effects of gravitational lensing on CMB constraints on neutrino rest mass and degeneracy parameter. We find for the PLANCK experiment that total (summed) neutrino mass M{sub ν} > 0.29 eV could be ruled out at 2σ or better. Likewise neutrino degeneracy parameters ξ{sub ν{sub e}} > 0.11 and |ξ{sub ν{sub μ{sub /{sub τ}}}}| > 0.49 could be detected or ruled out at 2σ confidence, or better. For POLARBEAR we find that the corresponding detectable values are M{sub ν} > 0.75 eV, ξ{sub ν{sub e}} > 0.62, and |ξ{sub ν{sub μ{sub /{sub τ}}}}| > 1.1, while for EPIC we obtain M{sub ν} > 0.20 eV, ξ{sub ν{sub e}} > 0.045, and |ξ{sub ν{sub μ{sub /{sub τ}}}}| > 0.29. Our forcast for EPIC demonstrates that CMB observations have the potential to set constraints on neutrino degeneracy parameters which are better than BBN-derived limits and an order of magnitude better than current WMAP-derived limits.

  11. Unveiling secret interactions among sterile neutrinos with big-bang nucleosynthesis

    Science.gov (United States)

    Saviano, Ninetta; Pisanti, Ofelia; Mangano, Gianpiero; Mirizzi, Alessandro

    2014-12-01

    Short-baseline neutrino anomalies suggest the existence of low-mass [m ˜O (1 ) eV ] sterile neutrinos νs. These would be efficiently produced in the early universe by oscillations with active neutrino species, leading to a thermal population of the sterile states seemingly incompatible with cosmological observations. In order to relieve this tension it has been recently speculated that new "secret" interactions among sterile neutrinos, mediated by a massive gauge boson X (with MX≪MW), can inhibit or suppress the sterile neutrino thermalization, due to the production of a large matter potential term. We note however, that they also generate strong collisional terms in the sterile neutrino sector that induce an efficient sterile neutrino production after a resonance in matter is encountered, increasing their contribution to the number of relativistic particle species Neff. Moreover, for values of the parameters of the νs-νs interaction for which the resonance takes place at temperature T ≲few MeV , significant distortions are produced in the electron (anti)neutrino spectra, altering the abundance of light element in big bang nucleosynthesis (BBN). Using the present determination of 4He and deuterium primordial abundances we determine the BBN constraints on the model parameters. We find that 2H/H density ratio exclude much of the parameter space if one assumes a baryon density at the best fit value of Planck experiment, ΩBh2=0.02207 , while bounds become weaker for a higher ΩBh2=0.02261 , the 95% C.L. upper bound of Planck. Due to the large error on its experimental determination, the helium mass fraction Yp gives no significant bounds.

  12. Neutron capture studies with a short flight path

    Science.gov (United States)

    Walter, Stephan; Heil, Michael; Käppeler, Franz; Plag, Ralf; Reifarth, René

    The time of flight (TOF) method is an important tool for the experimental determination of neu- tron capture cross sections which are needed for s-process nucleosynthesis in general, and for analyses of branchings in the s-process reaction path in particular. So far, sample masses of at least several milligrams are required to compensate limitations in the currently available neutron fluxes. This constraint leads to unacceptable backgrounds for most of the relevant unstable branch point nuclei, due to the decay activity of the sample. A possible solution has been proposed by the NCAP project at the University of Frankfurt. A first step in this direction is reported here, which aims at enhancing the sensitivity of the Karlsruhe TOF array by reducing the neutron flight path to only a few centimeters. Though sample masses in the microgram regime can be used by this approach, the increase in neutron flux has to be paid by a higher background from the prompt flash related to neutron production. Test measurements with Au samples are reported.

  13. Proton-proton colliding beam facility ISABELLE

    International Nuclear Information System (INIS)

    Hahn, H.

    1980-01-01

    This paper attempts to present the status of the ISABELLE construction project, which has the objective of building a 400 + 400 GeV proton colliding beam facility. The major technical features of the superconducting accelerators with their projected performance are described. Progress made so far, difficulties encountered, and the program until completion in 1986 is briefly reviewed

  14. Observation of two photons in n-p capture

    International Nuclear Information System (INIS)

    Dress, W.B. Jr.

    1972-01-01

    The observation of two gamma rays in coincidence following the capture of subthermal neutrons by protons in water is reported. The measured branching ratio of two-gamma events to single-gamma events in the energy range of 600 keV to 1620 keV was found to be 0.0011 +- 0.0002. Possible sources of systematic error are also considered. (8 figures) (U.S.)

  15. EVOLUTION, NUCLEOSYNTHESIS, AND YIELDS OF LOW-MASS ASYMPTOTIC GIANT BRANCH STARS AT DIFFERENT METALLICITIES. II. THE FRUITY DATABASE

    International Nuclear Information System (INIS)

    Cristallo, S.; Domínguez, I.; Abia, C.; Piersanti, L.; Straniero, O.; Gallino, R.; Di Rico, G.; Quintini, M.; Bisterzo, S.

    2011-01-01

    By using updated stellar low-mass stars models, we systematically investigate the nucleosynthesis processes occurring in asymptotic giant branch (AGB) stars. In this paper, we present a database dedicated to the nucleosynthesis of AGB stars: FRANEC Repository of Updated Isotopic Tables and Yields (FRUITY). An interactive Web-based interface allows users to freely download the full (from H to Bi) isotopic composition, as it changes after each third dredge-up (TDU) episode and the stellar yields the models produce. A first set of AGB models, having masses in the range 1.5 ≤M/M ☉ ≤ 3.0 and metallicities 1 × 10 –3 ≤ Z ≤ 2 × 10 –2 , is discussed. For each model, a detailed description of the physical and the chemical evolution is provided. In particular, we illustrate the details of the s-process and we evaluate the theoretical uncertainties due to the parameterization adopted to model convection and mass loss. The resulting nucleosynthesis scenario is checked by comparing the theoretical [hs/ls] and [Pb/hs] ratios to those obtained from the available abundance analysis of s-enhanced stars. On the average, the variation with the metallicity of these spectroscopic indexes is well reproduced by theoretical models, although the predicted spread at a given metallicity is substantially smaller than the observed one. Possible explanations for such a difference are briefly discussed. An independent check of the TDU efficiency is provided by the C-stars luminosity function. Consequently, theoretical C-stars luminosity functions for the Galactic disk and the Magellanic Clouds have been derived. We generally find good agreement with observations.

  16. Evolution, Nucleosynthesis, and Yields of Low-mass Asymptotic Giant Branch Stars at Different Metallicities. II. The FRUITY Database

    Science.gov (United States)

    Cristallo, S.; Piersanti, L.; Straniero, O.; Gallino, R.; Domínguez, I.; Abia, C.; Di Rico, G.; Quintini, M.; Bisterzo, S.

    2011-12-01

    By using updated stellar low-mass stars models, we systematically investigate the nucleosynthesis processes occurring in asymptotic giant branch (AGB) stars. In this paper, we present a database dedicated to the nucleosynthesis of AGB stars: FRANEC Repository of Updated Isotopic Tables & Yields (FRUITY). An interactive Web-based interface allows users to freely download the full (from H to Bi) isotopic composition, as it changes after each third dredge-up (TDU) episode and the stellar yields the models produce. A first set of AGB models, having masses in the range 1.5 3.0 and metallicities 1 × 10-3 <= Z <= 2 × 10-2, is discussed. For each model, a detailed description of the physical and the chemical evolution is provided. In particular, we illustrate the details of the s-process and we evaluate the theoretical uncertainties due to the parameterization adopted to model convection and mass loss. The resulting nucleosynthesis scenario is checked by comparing the theoretical [hs/ls] and [Pb/hs] ratios to those obtained from the available abundance analysis of s-enhanced stars. On the average, the variation with the metallicity of these spectroscopic indexes is well reproduced by theoretical models, although the predicted spread at a given metallicity is substantially smaller than the observed one. Possible explanations for such a difference are briefly discussed. An independent check of the TDU efficiency is provided by the C-stars luminosity function. Consequently, theoretical C-stars luminosity functions for the Galactic disk and the Magellanic Clouds have been derived. We generally find good agreement with observations.

  17. Recoil separators for radiative capture using radioactive ion beams. Recent advances and detection techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Chris [TRIUMF, Vancouver, BC (Canada); Greife, Uwe; Hager, Ulrike [Colorado School of Mines, Golden, CO (United States)

    2014-06-15

    Radiative capture reactions involving the fusion of hydrogen or helium are ubiquitous in the stellar history of the universe, and are some of the most important reactions in the processes that govern nucleosynthesis and energy generation in both static and explosive scenarios. However, radiative capture reactions pose some of the most difficult experimental challenges due to extremely small cross sections. With the advent of recoil separators and techniques in inverse kinematics, it is now possible to measure radiative capture reactions on very short-lived radioactive nuclei, and in the presence of high experimental backgrounds. In this paper we review the experimental needs for making measurements of astrophysical importance on radiative capture reactions. We also review some of the important historical advances in the field of recoil separators as well as describe current techniques and performance milestones, including descriptions of some of the separators most recently working at radioactive ion beam facilities, such as DRAGON at TRIUMF and the DRS at the Holifield Radioactive Ion Beam Facility. We will also summarize some of the scientific highlight measurements at the RIB facilities. (orig.)

  18. High-resolution neutron capture and transmission measurements and the stellar neutron capture cross sections of 116,120Sn

    International Nuclear Information System (INIS)

    Koehler, P.E.; Spencer, R.R.; Guber, K.H.

    1997-01-01

    Improved astrophysical reaction rates for 116,120 Sn(n, γ) are of interest because nucleosynthesis models have not been able to reproduce the observed abundances in this mass region. For example, previous s-process calculations have consistently underproduced the s-only isotope 116 Sn. Also, these studies have resulted in residual reprocess abundances for the tin isotopes which are systematically larger than predicted by reprocess calculations. It has been suggested that these problems could be solved by reducing the solar tin abundance by 10-20%, but there is no experimental evidence to justify this renormalization. Instead, it is possible that the problem lies in the (n,T) cross sections used in the reaction network calculations or in the s-process models. One reason to suspect the (n, γ) data is that previous measurements did not extend to low enough energies to determine accurately the Maxwellian-averaged capture cross sections at the low temperatures (kT=6-8 keV) favored by the most recent stellar models of the s process. Also, the two most recent high-precision measurements of the 120 Sn(n, γ) cross section are in serious disagreement. Because of its small size, this cross section could affect (via the s-process branching at 121 Sn) the relative abundances of the three s-only isotopes of Te

  19. Radionuclides 26Al, 53Mn and 60Fe as a test of the possible nucleosynthesis immediately before solar system formation

    International Nuclear Information System (INIS)

    Chechev, V.P.

    2000-01-01

    Parameters of a possible burst of nucleosynthesis just prior to the solar system formation were calculated on the basis of data on occurrence of 26 Al, 53 Mn and 60 Fe radionuclides in the early solar system. The whole number of the observance data was shown to result in the following restrictions of the parameters of the mentioned burst: its contribution into the general galactic synthesis of the elements did not exceed 0.5 % while time interval from the burst up to hardening of meteorites did not exceed 10 mln. years [ru

  20. Using Inertial Fusion Implosions to Measure the T+^{3}He Fusion Cross Section at Nucleosynthesis-Relevant Energies.

    Science.gov (United States)

    Zylstra, A B; Herrmann, H W; Johnson, M Gatu; Kim, Y H; Frenje, J A; Hale, G; Li, C K; Rubery, M; Paris, M; Bacher, A; Brune, C R; Forrest, C; Glebov, V Yu; Janezic, R; McNabb, D; Nikroo, A; Pino, J; Sangster, T C; Séguin, F H; Seka, W; Sio, H; Stoeckl, C; Petrasso, R D

    2016-07-15

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

  1. Big-bang nucleosynthesis through bound-state effects with a long-lived slepton in the NMSSM

    Science.gov (United States)

    Kohri, Kazunori; Koike, Masafumi; Konishi, Yasufumi; Ohta, Shingo; Sato, Joe; Shimomura, Takashi; Sugai, Kenichi; Yamanaka, Masato

    2014-08-01

    We show that the Li problems can be solved in the next-to-minimal supersymmetric standard model where the slepton as the next-to-lightest supersymmetric (SUSY) particle is very long lived. Such a long-lived slepton induces exotic nuclear reactions in big-bang nucleosynthesis, and destroys and produces the Li7 and Li6 nuclei via bound state formation. We study cases where the lightest SUSY particle is singlino-like neutralino and bino-like neutralino to present allowed regions in the parameter space, which is consistent with the observations on the dark matter and the Higgs mass.

  2. Proton storage rings

    International Nuclear Information System (INIS)

    Rau, R.R.

    1978-04-01

    A discussion is given of proton storage ring beam dynamic characteristics. Topics considered include: (1) beam energy; (2) beam luminosity; (3) limits on beam current; (4) beam site; (5) crossing angle; (6) beam--beam interaction; (7) longitudinal instability; (8) effects of scattering processes; (9) beam production; and (10) high magnetic fields. Much of the discussion is related to the design parameters of ISABELLE, a 400 x 400 GeV proton---proton intersecting storage accelerator to be built at Brookhaven National Laboratory

  3. ATLAS Forward Proton Detector

    CERN Document Server

    Grieco, Chiara; The ATLAS collaboration

    2018-01-01

    The aim of the ATLAS Forward Proton (AFP) detector system is the measurement of protons scattered diffractively or electromagnetically at very small angles. The full two-arm setup was installed during the 2016/2017 EYETS. This allows measurements of processes with two forward protons: central diffraction, exclusive production, and two-photon processes. In 2017, AFP participated in the ATLAS high-luminosity data taking on the day-by-day basis. In addition, several special runs with reduced luminosity were taken. The poster will present the AFP detectors and the lessons learned from the last year operation and some performance from 2016 and 2017.

  4. Motion Capturing Emotions

    Directory of Open Access Journals (Sweden)

    Wood Karen

    2017-12-01

    Full Text Available The paper explores the activities conducted as part of WhoLoDancE: Whole Body Interaction Learning for Dance Education which is an EU-funded Horizon 2020 project. In particular, we discuss the motion capture sessions that took place at Motek, Amsterdam as well as the dancers’ experience of being captured and watching themselves or others as varying visual representations through the HoloLens. HoloLens is Microsoft’s first holographic computer that you wear as you would a pair of glasses. The study embraced four dance genres: Ballet, Contemporary, Flamenco and Greek Folk dance. We are specifically interested in the kinesthetic and emotional engagement with the moving body and what new corporeal awareness may be experienced. Positioning the moving, dancing body as fundamental to technological advancements, we discuss the importance of considering the dancer’s experience in the real and virtual space. Some of the artists involved in the project have offered their experiences, which are included, and they form the basis of the discussion. In addition, we discuss the affect of immersive environments, how these environments expand reality and what effect (emotionally and otherwise that has on the body. The research reveals insights into relationships between emotion, movement and technology and what new sensorial knowledge this evokes for the dancer.

  5. Synovectomy by Neutron capture

    International Nuclear Information System (INIS)

    Vega C, H.R.; Torres M, C.

    1998-01-01

    The Synovectomy by Neutron capture has as purpose the treatment of the rheumatoid arthritis, illness which at present does not have a definitive curing. This therapy requires a neutron source for irradiating the articulation affected. The energy spectra and the intensity of these neutrons are fundamental since these neutrons induce nuclear reactions of capture with Boron-10 inside the articulation and the freely energy of these reactions is transferred at the productive tissue of synovial liquid, annihilating it. In this work it is presented the neutron spectra results obtained with moderator packings of spherical geometry which contains in its center a Pu 239 Be source. The calculations were realized through Monte Carlo method. The moderators assayed were light water, heavy water base and the both combination of them. The spectra obtained, the average energy, the neutron total number by neutron emitted by source, the thermal neutron percentage and the dose equivalent allow us to suggest that the moderator packing more adequate is what has a light water thickness 0.5 cm (radius 2 cm) and 24.5 cm heavy water (radius 26.5 cm). (Author)

  6. Radioactivity induced by neutrons: Enrico Fermi and a thermodynamic approach to radiative capture

    Science.gov (United States)

    De Gregorio, Alberto

    2006-07-01

    When Fermi learned that slow neutrons are much more effective than fast ones in inducing radioactivity, he explained this phenomenon by mentioning the well-known scattering cross section between neutrons and protons. At this early stage, he did not refer to the capture cross section by target nuclei. At the same time a thermodynamic approach to neutron-proton capture was being discussed by physicists: neutron capture was interpretated as the reverse of deuteron photodissociation and detailed balance among neutrons, protons, deuterons, and radiation was invoked. This thermodynamic approach might underlie Fermi's early explanation of the great efficiency of slow neutrons. Fermi repeatedly used a thermodynamic approach that had been used in describing some of the physical properties of conductors by Richardson and had been influential in Fermi's youth.

  7. Proton computed tomography

    International Nuclear Information System (INIS)

    Hanson, K.M.

    1978-01-01

    The use of protons or other heavy charged particles instead of x rays in computed tomography (CT) is explored. The results of an experimental implementation of proton CT are presented. High quality CT reconstructions are obtained at an average dose reduction factor compared with an EMI 5005 x-ray scanner of 10:1 for a 30-cm-diameter phantom and 3.5:1 for a 20-cm diameter. The spatial resolution is limited by multiple Coulomb scattering to about 3.7 mm FWHM. Further studies are planned in which proton and x-ray images of fresh human specimens will be compared. Design considerations indicate that a clinically useful proton CT scanner is eminently feasible

  8. Electron - proton colliders

    International Nuclear Information System (INIS)

    Wiik, B.H.

    1985-01-01

    Electron-proton storage rings allow us to study the interaction between the two basic constituents of matter, electrons and quarks at very short distances. Such machines were first discussed in connection with the ISR but the idea was abandoned because of the anticipated low counting rate. The interest in electron-proton storage rings was rekindeled by the discovery of large pointlike cross sections in lepton-hardon interactions and several/sup 2-15/ projects have been discussed during the past decade. However, despite a glorious past, which includes the discovery of quarks and neutral currents, and a multitude of proposals no electron-proton storage ring has ever been built. What we might learn by studying electron-proton collisions at high energies is discussed. After some brief comments on present proposals the proposed DESY ep project HERA is described as an example of how to realize such a machine

  9. Apparatus for proton radiography

    International Nuclear Information System (INIS)

    Martin, R.L.

    1976-01-01

    An apparatus for effecting diagnostic proton radiography of patients in hospitals comprises a source of negative hydrogen ions, a synchrotron for accelerating the negative hydrogen ions to a predetermined energy, a plurality of stations for stripping extraction of a radiography beam of protons, means for sweeping the extracted beam to cover a target, and means for measuring the residual range, residual energy, or percentage transmission of protons that pass through the target. The combination of information identifying the position of the beam with information about particles traversing the subject and the back absorber is performed with the aid of a computer to provide a proton radiograph of the subject. In an alternate embodiment of the invention, a back absorber comprises a plurality of scintillators which are coupled to detectors. 10 claims, 7 drawing figures

  10. Plant proton pumps

    DEFF Research Database (Denmark)

    Gaxiola, Roberto A.; Palmgren, Michael Gjedde; Schumacher, Karin

    2007-01-01

    Chemiosmotic circuits of plant cells are driven by proton (H+) gradients that mediate secondary active transport of compounds across plasma and endosomal membranes. Furthermore, regulation of endosomal acidification is critical for endocytic and secretory pathways. For plants to react...

  11. Inauguration of Proton Synchrotron

    CERN Multimedia

    1960-01-01

    On 5 February 1960, the Proton Synchrotron (PS) was formally inaugurated. The great Danish physicist, Niels Bohr, releases a bottle of champagne against a shielding block to launch the PS on its voyage in physics.

  12. Single Degenerate Models for Type Ia Supernovae: Progenitor's Evolution and Nucleosynthesis Yields

    Science.gov (United States)

    Nomoto, Ken'ichi; Leung, Shing-Chi

    2018-06-01

    . The companion star has become a He WD and CSM has disappeared: "SN Ia-He WD". We update nucleosynthesis yields of the carbon deflagration model W7, delayed detonation model WDD2, and the sub-Chandrasekhar mass model to provide some constraints on the yields (such as Mn) from the comparison with the observations. We note the important metallicity effects on 58Ni and 55Mn.

  13. Constraints on neutrino degeneracy from the cosmic microwave background and primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Orito, M.; Kajino, T.; Mathews, G. J.; Wang, Y.

    2002-01-01

    We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy based upon the latest high resolution CMB sky maps from BOOMERANG, DASI, and MAXIMA-1. We generate likelihood functions by marginalizing over (Ω b h 2 ,ξ ν μ,τ ,ξ ν e ,Ω Λ ,h,n) plus the calibration uncertainties. We consider flat Ω M +Ω Λ =1 cosmological models with two identical degenerate neutrino species, ξ ν μ,τ ≡ vertical bar ξ ν μ vertical bar = vertical bar ξ ν τ vertical bar and a small ξ ν e . We assign weak top-hat priors on the electron-neutrino degeneracy parameter ξ ν e and Ω b h 2 based upon allowed values consistent with the nucleosynthesis constraints as a function of ξ ν μ,τ . The change in the background neutrino temperature with degeneracy is also explicitly included, and Gaussian priors for h=0.72±0.08 and the experimental calibration uncertainties are adopted. The marginalized likelihood functions show a slight (0.5σ) preference for neutrino degeneracy. Optimum values with two equally degenerate μ and τ neutrinos imply ξ ν μ,τ =1.0 -1.0(0.5σ) +0.8(1σ) ,from which we deduce ξ ν e =0.09 -0.09 +0.15 , and Ω b h 2 =0.021 -0.002 +0.06 . The 2σ upper limit becomes ξ ν μ,τ ≤2.1, which implies ξ ν e ≤0.30, and Ω b h 2 ≤0.030. For only a single large-degeneracy species the optimal value is vertical bar ξ ν μ vertical bar or vertical bar ξ ν τ vertical bar =1.4 with a 2σ upper limit of vertical bar ξ ν μ vertical bar or vertical bar ξ ν τ vertical bar ≤2.5.

  14. Massive black holes and light-element nucleosynthesis in a baryonic universe

    Science.gov (United States)

    Gnedin, Nickolay Y.; Ostriker, Jeremiah P.; Rees, Martin J.

    1995-01-01

    We reexamine the model proposed by Gnedin & Ostriker (1992) in which Jeans mass black holes (M(sub BH) approximately = 10(exp 6) solar mass) form shortly after decoupling. There is no nonbaryonic dark matter in this model, but we examine the possibility that Omega(sub b) is considerably larger than given by normal nucleosynthesis. Here we allow for the fact that much of the high baryon-to-photon ratio material will collapse leaving the universe of remaining material with light-element abundances more in accord with the residual baryonic density (approximately = 10(exp -2)) than with Omega(sub 0) and the initial baryonic density (approximately = 10(exp -1)). We find that no reasonable model can be made with random-phase density fluctuations, if the power on scales smaller than 10(exp 6) solar mass is as large as expected. However, phase-correlated models of the type that might occur in connection with topological singularities can be made with Omega(sub b) h(exp 2) = 0.013 +/- 0.001, 0.15 approximately less than Omega(sub 0) approximately less than 0.4, which are either flat (Omega(sub lambda) = 1 - Omega(sub 0)) or open (Omega(sub lambda) = 0) and which satisfy all the observational constraints which we apply, including the large baryon-to-total mass ratio found in the X-ray clusters. The remnant baryon density is thus close to that obtained in the standard picture (Omega(sub b) h(exp 2) = 0.0125 +/- 0.0025; Walker et al. 1991). The spectral index implied for fluctuations in the baryonic isocurvature scenario, -1 less than m less than 0, is in the range expected by other arguments based on large-scale structure and microwave fluctuation constraints. The dark matter in this picture is in the form of massive black holes. Accretion onto them at early epochs releases high-energy photons which significantly heat and reionize the universe. But photodissociation does not materially change light-element abundances. A typical model gives bar-y approximately = 1 x 10(exp -5

  15. Experimental challenge to the big-bang nucleosynthesis - Cosmological 7Li problem in BBN

    Science.gov (United States)

    Kubono, S.; Kawabata, T.; Hou, S. Q.; He, J. J.

    2018-04-01

    The primordial nucleosynthesis(BBN) right after the big bang (BB) is one of the key elements that basically support the BB model. The BBN is well known that it produced primarily light elements, and explains reasonably most of the elemental abundances. However, there remains an interesting and serious question. That is so called the cosmological 7Li problem in BBN. The BBN simulations using nuclear data together with the recent detailed micro-wave background measurements explain most of the light elements including D, 4He, etc, but the 7Li abundance is over predicted roughly by a factor of three. Although this problem should be investigated in all the fields relevant including physics and astronomical observations, I will concentrate my discussion on the nuclear physics side, especially the recent progress for studying the last possible major destruction process of 7Be, the 7Be(n,α)4He reaction, which would reduce the overproduction if the cross section is large. There are several efforts recently made for the 7Be(n,α)4He reaction in the world. A new theoretical estimate was made compiling all available data of the mirror reaction 7Li(p,α)4He, suggesting about one order smaller reaction rate than the ones currently being used (Wagoner rate). The n-TOF group measured some part of the s-wave components of the reaction, suggesting that the s-wave contributions are much smaller than the Wagoner rate. The p-wave component was measured clearly at RCNP, Osaka using the time-reverse reaction 4He(α,n)7Be, indicating that the p-wave contribution dominates at the effective temperature region for the BBN. However, the sum of the s-wave and p-wave contributions is about one order of magnitude smaller than the Wagoner rate. It should be of great interest to confirm by the indirect method, Trojan-Horse method to deduce cross sections at the effective temperature region, and also see the cross sections for a wider energy range systematically, which is under way by the BELICOS

  16. Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mangano, Gianpiero; Miele, Gennaro; Pisanti, Ofelia; Sarikas, Srdjan [Istituto Nazionale di Fisica Nucleare – Sezione di Napoli, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Pastor, Sergio, E-mail: mangano@na.infn.it, E-mail: miele@na.infn.it, E-mail: pastor@ific.uv.es, E-mail: pisanti@na.infn.it, E-mail: sarikas@na.infn.it [Instituto de Física Corpuscular (CSIC-Universitat de València), Ed. Institutos de Investigación, Apdo. correos 22085, E-46071 Valencia (Spain)

    2011-03-01

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N{sub eff}. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N{sub eff} from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, η{sub ν} = η{sub ν{sub e}}+η{sub ν{sub μ}}+η{sub ν{sub τ}} and the initial electron neutrino asymmetry η{sub ν{sub e}{sup in}}, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the ν{sub e}−ν-bar {sub e} asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial {sup 2}H/H density ratio and {sup 4}He mass fraction. Note that taking the baryon fraction as measured by WMAP, the {sup 2}H/H abundance plays a relevant role in constraining the allowed regions in the η{sub ν}−η{sub ν{sub e}{sup in}} plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N{sub eff} as a function of the mixing parameter θ{sub 13}, and point out the upper bound N{sub eff}∼<3.4. Comparing these results with the forthcoming measurement of N{sub eff} by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.

  17. Proton beam therapy facility

    International Nuclear Information System (INIS)

    1984-01-01

    It is proposed to build a regional outpatient medical clinic at the Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois, to exploit the unique therapeutic characteristics of high energy proton beams. The Fermilab location for a proton therapy facility (PTF) is being chosen for reasons ranging from lower total construction and operating costs and the availability of sophisticated technical support to a location with good access to patients from the Chicago area and from the entire nation. 9 refs., 4 figs., 26 tabs

  18. Proton beam therapy facility

    Energy Technology Data Exchange (ETDEWEB)

    1984-10-09

    It is proposed to build a regional outpatient medical clinic at the Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois, to exploit the unique therapeutic characteristics of high energy proton beams. The Fermilab location for a proton therapy facility (PTF) is being chosen for reasons ranging from lower total construction and operating costs and the availability of sophisticated technical support to a location with good access to patients from the Chicago area and from the entire nation. 9 refs., 4 figs., 26 tabs.

  19. Robust automated knowledge capture.

    Energy Technology Data Exchange (ETDEWEB)

    Stevens-Adams, Susan Marie; Abbott, Robert G.; Forsythe, James Chris; Trumbo, Michael Christopher Stefan; Haass, Michael Joseph; Hendrickson, Stacey M. Langfitt

    2011-10-01

    This report summarizes research conducted through the Sandia National Laboratories Robust Automated Knowledge Capture Laboratory Directed Research and Development project. The objective of this project was to advance scientific understanding of the influence of individual cognitive attributes on decision making. The project has developed a quantitative model known as RumRunner that has proven effective in predicting the propensity of an individual to shift strategies on the basis of task and experience related parameters. Three separate studies are described which have validated the basic RumRunner model. This work provides a basis for better understanding human decision making in high consequent national security applications, and in particular, the individual characteristics that underlie adaptive thinking.

  20. Fragment capture device

    Science.gov (United States)

    Payne, Lloyd R.; Cole, David L.

    2010-03-30

    A fragment capture device for use in explosive containment. The device comprises an assembly of at least two rows of bars positioned to eliminate line-of-sight trajectories between the generation point of fragments and a surrounding containment vessel or asset. The device comprises an array of at least two rows of bars, wherein each row is staggered with respect to the adjacent row, and wherein a lateral dimension of each bar and a relative position of each bar in combination provides blockage of a straight-line passage of a solid fragment through the adjacent rows of bars, wherein a generation point of the solid fragment is located within a cavity at least partially enclosed by the array of bars.

  1. Capturing the Daylight Dividend

    Energy Technology Data Exchange (ETDEWEB)

    Peter Boyce; Claudia Hunter; Owen Howlett

    2006-04-30

    Capturing the Daylight Dividend conducted activities to build market demand for daylight as a means of improving indoor environmental quality, overcoming technological barriers to effective daylighting, and informing and assisting state and regional market transformation and resource acquisition program implementation efforts. The program clarified the benefits of daylight by examining whole building systems energy interactions between windows, lighting, heating, and air conditioning in daylit buildings, and daylighting's effect on the human circadian system and productivity. The project undertook work to advance photosensors, dimming systems, and ballasts, and provided technical training in specifying and operating daylighting controls in buildings. Future daylighting work is recommended in metric development, technology development, testing, training, education, and outreach.

  2. PROTON MICROSCOPY AT FAIR

    International Nuclear Information System (INIS)

    Merrill, F. E.; Mariam, F. G.; Golubev, A. A.; Turtikov, V. I.; Varentsov, D.

    2009-01-01

    Proton radiography was invented in the 1990's at Los Alamos National Laboratory (LANL) as a diagnostic to study dynamic material properties under extreme pressures, strain and strain rate. Since this time hundreds of dynamic proton radiography experiments have been performed at LANL and a facility has been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia for similar applications in dynamic material studies. Recently an international effort has investigated a new proton radiography capability for the study of dynamic material properties at the Facility for Anti-proton and Ion Research (FAIR) located in Darmstadt, Germany. This new Proton microscope for FAIR(PRIOR) will provide radiographic imaging of dynamic systems with unprecedented spatial, temporal and density resolution, resulting in a window for understanding dynamic material properties at new length scales. It is also proposed to install the PRIOR system at the GSI Helmholtzzentrum fuer Schwerionenforschung before installation at FAIR for dynamic experiments with different drivers including high explosives, pulsed power and lasers. The design of the proton microscope and expected radiographic performance is presented.

  3. Multicavity proton cyclotron accelerator

    Directory of Open Access Journals (Sweden)

    J. L. Hirshfield

    2002-08-01

    Full Text Available A mechanism for acceleration of protons is described, in which energy gain occurs near cyclotron resonance as protons drift through a sequence of rotating-mode TE_{111} cylindrical cavities in a strong nearly uniform axial magnetic field. Cavity resonance frequencies decrease in sequence from one another with a fixed frequency interval Δf between cavities, so that synchronism can be maintained between the rf fields and proton bunches injected at intervals of 1/Δf. An example is presented in which a 122 mA, 1 MeV proton beam is accelerated to 961 MeV using a cascade of eight cavities in an 8.1 T magnetic field, with the first cavity resonant at 120 MHz and with Δf=8 MHz. Average acceleration gradient exceeds 40 MV/m, average effective shunt impedance is 223 MΩ/m, but maximum surface field in the cavities does not exceed 7.2 MV/m. These features occur because protons make many orbital turns in each cavity and thus experience acceleration from each cavity field many times. Longitudinal and transverse stability appear to be intrinsic properties of the acceleration mechanism, and an example to illustrate this is presented. This acceleration concept could be developed into a proton accelerator for a high-power neutron spallation source, such as that required for transmutation of nuclear waste or driving a subcritical fission burner, provided a number of significant practical issues can be addressed.

  4. A potential diagnostic for low energy, nonthermal protons in solar flares

    International Nuclear Information System (INIS)

    MacKinnon, A.L.

    1989-01-01

    The current uncertainty in flare research regarding the role of low energy (<1 MeV) protons demands that we consider any possibilities for directly constraining their number and energy content. Here we point out that γ-ray lines, from radiative capture reactions of such protons, may in principle provide such constraints. Making allowance for the possibility that the protons slow down in a warm target, we show how observational upper limits to their strengths may be used to constrain the proton energy content and the temperature of the interaction region

  5. Electron clearing for the ISA proton beam

    International Nuclear Information System (INIS)

    Herrera, J.C.

    1976-01-01

    The circulating protons in the ISABELLE intersecting storage ring accelerator will collide with the residual gas in the vacuum chamber. The electrons produced will tend to be captured by the potential well of the beam itself and result in a neutralization of the space charge of the beam. A detailed analysis is given of the various mechanisms which can be used to reduce the net degree of beam neutralization. It is concluded that the average neutralization will be about 10 -4 for a residual gas pressure of 3 x 10 -11 torr of hydrogen

  6. Proton Radiography to Improve Proton Radiotherapy : Simulation Study at Different Proton Beam Energies

    NARCIS (Netherlands)

    Biegun, Aleksandra; Takatsu, Jun; van Goethem, Marc-Jan; van der Graaf, Emiel; van Beuzekom, Martin; Visser, Jan; Brandenburg, Sijtze

    To improve the quality of cancer treatment with protons, a translation of X-ray Computed Tomography (CT) images into a map of the proton stopping powers needs to be more accurate. Proton stopping powers determined from CT images have systematic uncertainties in the calculated proton range in a

  7. Simple, empirical approach to predict neutron capture cross sections from nuclear masses

    Science.gov (United States)

    Couture, A.; Casten, R. F.; Cakirli, R. B.

    2017-12-01

    neutron capture cross sections, extending far from stability, including for nuclei of the highest sensitivity to r -process nucleosynthesis.

  8. The AGB star nucleosynthesis in the light of the recent {sup 17}O(p,α){sup 14}N and {sup 18}O(p,α){sup 15}N reaction rate determinations

    Energy Technology Data Exchange (ETDEWEB)

    Palmerini, S.; Sergi, M. L.; La Cognata, M.; Pizzone, R. G. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Lamia, L. [Dipartimento di Fisica e Astronomia, Universitá degli Studi di Catania (Italy); Spitaleri, C. [INFN-Laboratori Nazionali del Sud, Catania, Italy and Dipartimento di Fisica e Astronomia, Universitá degli Studi di Catania (Italy)

    2015-02-24

    Presolar grains form in the cold and dusty envelopes of Asymptotic Giant Branch (AGB) stars. These solides, once that have been ejected by stellar winds, come to us as inclusions in meteorites providing invaluable benchmarks and constraints for our knowledge of low temeperature H-burning in stars. The Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of the {sup 17}O(p,α){sup 14}N and {sup 18}O(p,α){sup 15}N reactions. Moreover, the strength of the 65 keV resonance in the {sup 17}O(p,α){sup 14}N reaction, measured by means of the THM, has been used to renormalize the corresponding resonance strength in the {sup 17}O+p radiative capture channel. The new estimates of the reaction rates have been introduced into calculations of AGB star nucleosynthesis and the results have been compared with geochemical analysis of 'presolar' grains to determine their impact on astrophysical environments.

  9. Capture of muons with high energy transfer (μ-,pn) on the 2040Ca

    International Nuclear Information System (INIS)

    Arques, Marc

    1978-01-01

    As several Russian experiments had shown that the capture of mesons of negative charge in some target nuclei (Si, S, Ca, Cu, Pb) could lead to the emission of high energy protons and neutrons (a kinetic energy higher than 30 MeV), the author reports a preliminary measurement of the capture or a negatively charged muon in a K orbit around a nucleus, actually a capture with a simultaneous emission of a proton and a neutron, and of a neutrino with an as low as possible energy. After having outlined the interest of such an experiment, the author describes the kinematics of capture of a resting muon, the production of muons, the experimental assembly, the experiment and the associated electronics. Results are interpreted

  10. Capture cross sections for very heavy systems

    International Nuclear Information System (INIS)

    Rowley, N.; Grar, N.; Ntshangase, S.S.

    2006-01-01

    In intermediate-mass systems, collective excitations of the target and projectile can greatly enhance the sub-barrier capture cross section σ cap by giving rise to a distribution of Coulomb barriers. For such systems, capture essentially leads directly to fusion (formation of a compound nucleus (CN)), which then decays through the emission of light particles (neutrons, protons, and alpha particles). Thus the evaporation-residue (ER) cross section is essentially equal to σ cap . For heavier systems the experimental situation is significantly more complicated due to the presence of quasifission (QF) (rapid separation into two fragments before the CN is formed) and by fusion-fission (FF) of the CN itself. Thus three cross sections need to be measured in order to evaluate σ cap . Although the ER essentially recoil along the beam direction. QF and FF fragments are scattered to all angles and require the measurement of angular distribution in order to obtain the excitation function and barrier distribution for capture. Two other approaches to this problem exist. If QF is not important, one can still measure just the ER cross section and try to reconstruct the corresponding σ cap through use of an evaporation-model code that takes account of the FF degree of freedom. Some earlier results on σ cap obtained in this way will be re-analyzed with detail coupled-channels calculations, and the extra-push phenomenon discussed. One may also try to obtain σ cap by exploiting unitarity, that is, by measuring instead the flux of particles corresponding to quasielastic (QE) scattering from the Coulomb barrier. Some new QE results obtained for the 86 Kr + 208 Pb system at iThemba LABS in South Africa will be presented [ru

  11. Neutron capture at the s-process branching points $^{171}$Tm and $^{204}$Tl

    CERN Multimedia

    Branching points in the s-process are very special isotopes for which there is a competition between the neutron capture and the subsequent b-decay chain producing the heavy elements beyond Fe. Typically, the knowledge on the associated capture cross sections is very poor due to the difficulty in obtaining enough material of these radioactive isotopes and to measure the cross section of a sample with an intrinsic activity; indeed only 2 out o the 21 ${s}$-process branching points have ever been measured by using the time-of-flight method. In this experiment we aim at measuring for the first time the capture cross sections of $^{171}$Tm and $^{204}$Tl, both of crucial importance for understanding the nucleosynthesis of heavy elements in AGB stars. The combination of both (n,$\\gamma$) measurements on $^{171}$Tm and $^{204}$Tl will allow one to accurately constrain neutron density and the strength of the 13C(α,n) source in low mass AGB stars. Additionally, the cross section of $^{204}$Tl is also of cosmo-chrono...

  12. Neutron capture therapy

    International Nuclear Information System (INIS)

    Jun, B. J.

    1998-11-01

    The overall state of the art related with neutron capture therapy(NCT) is surveyed. Since the field related with NCT is very wide, it is not intended to survey all related subjects in depth. The primary objective of this report is to help those working for the installation of a NCT facility and a PGNAA(prompt gamma ray neutron activation analysis) system for the boron analysis understand overall NCT at Hanaro. Therefore, while the parts of reactor neutron source and PGNAA are dealt in detail, other parts are limited to the level necessary to understand related fields. For example, the subject of chemical compound which requires intensive knowledge on chemistry, is not dealt as a separated item. However, the requirement of a compound for NCT, currently available compounds, their characteristics, etc. could be understood through this report. Although the subject of cancer treated by NCT is out of the capability of the author, it is dealt focussing its characteristics related with the success of NCT. Each detailed subject is expected to be dealt more detail by specialists in future. This report would be helpful for the researchers working for the NCT to understand related fields. (author). 128 refs., 3 tabs., 12 figs

  13. Captured by Aliens

    Science.gov (United States)

    Achenbach, Joel

    2000-03-01

    Captured by Aliens is a long and twisted voyage from science to the supernatural and back again. I hung out in Roswell, N.M., spent time with the Mars Society, met a guy who was figuring out the best way to build a spaceship to go to Alpha Centauri. I visited the set of the X-Files and talked to Mulder and Scully. One day over breakfast I was told by NASA administrator Dan Goldin, We live in a fog, man! He wants the big answers to the big questions. I spent a night in the base of a huge radio telescope in the boondocks of West Virginia, awaiting the signal from the aliens. I was hypnotized in a hotel room by someone who suspected that I'd been abducted by aliens and that this had triggered my interest in the topic. In the last months of his life, I talked to Carl Sagan, who believed that the galaxy riots with intelligent civilizations. He's my hero, for his steadfast adherence to the scientific method. What I found in all this is that the big question that needs immediate attention is not what's out THERE, but what's going on HERE, on Earth, and why we think the way we do, and how we came to be here in the first place.

  14. Proton therapy in Australia

    International Nuclear Information System (INIS)

    Jackson, M.

    2000-01-01

    Full text: Proton therapy has been in use since 1954 and over 25,000 patients have been treated worldwide. Until recently most patients were treated at physics research facilities but with the development of more compact and reliable accelerators it is now possible to realistically plan for proton therapy in an Australian hospital. The Australian National Proton Project has been formed to look at the feasibility of a facility which would be primarily for patient treatment but would also be suitable for research and commercial applications. A detailed report will be produced by the end of the year. The initial clinical experience was mainly with small tumours and other lesions close to critical organs. Large numbers of eye tumours have also been treated. Protons have a well-defined role in these situations and are now being used in the treatment of more common cancers. With the development of hospital-based facilities, over 2,500 patients with prostate cancer have been treated using a simple technique which gives results at least as good as radical surgery, external beam radiotherapy or brachytherapy. Importantly, the incidence of severe complications is very low. There are encouraging results in many disease sites including lung, liver, soft tissue sarcomas and oesophagus. As proton therapy becomes more widely available, randomised trials comparing it with conventional radiotherapy or Intensity Modulated Radiation Therapy (IMRT) will be possible. In most situations the use of protons will enable a higher dose to be given safely but in situations where local control rates are already satisfactory, protons are expected to produce less complications than conventional treatment. The initial costs of a proton facility are high but the recurrent costs are similar to other forms of high technology radiotherapy. . Simple treatment techniques with only a few fields are usually possible and proton therapy avoids the high integral doses associated with IMRT. This reduction in

  15. Proton dynamics in cancer.

    Science.gov (United States)

    Huber, Veronica; De Milito, Angelo; Harguindey, Salvador; Reshkin, Stephan J; Wahl, Miriam L; Rauch, Cyril; Chiesi, Antonio; Pouysségur, Jacques; Gatenby, Robert A; Rivoltini, Licia; Fais, Stefano

    2010-06-15

    Cancer remains a leading cause of death in the world today. Despite decades of research to identify novel therapeutic approaches, durable regressions of metastatic disease are still scanty and survival benefits often negligible. While the current strategy is mostly converging on target-therapies aimed at selectively affecting altered molecular pathways in tumor cells, evidences are in parallel pointing to cell metabolism as a potential Achilles' heel of cancer, to be disrupted for achieving therapeutic benefit. Critical differences in the metabolism of tumor versus normal cells, which include abnormal glycolysis, high lactic acid production, protons accumulation and reversed intra-extracellular pH gradients, make tumor site a hostile microenvironment where only cancer cells can proliferate and survive. Inhibiting these pathways by blocking proton pumps and transporters may deprive cancer cells of a key mechanism of detoxification and thus represent a novel strategy for a pleiotropic and multifaceted suppression of cancer cell growth.Research groups scattered all over the world have recently started to investigate various aspects of proton dynamics in cancer cells with quite encouraging preliminary results. The intent of unifying investigators involved in this research line led to the formation of the "International Society for Proton Dynamics in Cancer" (ISPDC) in January 2010. This is the manifesto of the newly formed society where both basic and clinical investigators are called to foster translational research and stimulate interdisciplinary collaboration for the development of more specific and less toxic therapeutic strategies based on proton dynamics in tumor cell biology.

  16. Proton dynamics in cancer

    Directory of Open Access Journals (Sweden)

    Pouysségur Jacques

    2010-06-01

    Full Text Available Abstract Cancer remains a leading cause of death in the world today. Despite decades of research to identify novel therapeutic approaches, durable regressions of metastatic disease are still scanty and survival benefits often negligible. While the current strategy is mostly converging on target-therapies aimed at selectively affecting altered molecular pathways in tumor cells, evidences are in parallel pointing to cell metabolism as a potential Achilles' heel of cancer, to be disrupted for achieving therapeutic benefit. Critical differences in the metabolism of tumor versus normal cells, which include abnormal glycolysis, high lactic acid production, protons accumulation and reversed intra-extracellular pH gradients, make tumor site a hostile microenvironment where only cancer cells can proliferate and survive. Inhibiting these pathways by blocking proton pumps and transporters may deprive cancer cells of a key mechanism of detoxification and thus represent a novel strategy for a pleiotropic and multifaceted suppression of cancer cell growth. Research groups scattered all over the world have recently started to investigate various aspects of proton dynamics in cancer cells with quite encouraging preliminary results. The intent of unifying investigators involved in this research line led to the formation of the "International Society for Proton Dynamics in Cancer" (ISPDC in January 2010. This is the manifesto of the newly formed society where both basic and clinical investigators are called to foster translational research and stimulate interdisciplinary collaboration for the development of more specific and less toxic therapeutic strategies based on proton dynamics in tumor cell biology.

  17. Polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

  18. Journal of Proton Therapy

    Directory of Open Access Journals (Sweden)

    Editorial Office

    2015-01-01

    Full Text Available Journal of Proton Therapy (JPT is an international open access, peer-reviewed journal, which publishes original research, technical reports, reviews, case reports, editorials, and other materials on proton therapy with focus on radiation oncology, medical physics, medical dosimetry, and radiation therapy.No article processing/submission feeNo publication feePeer-review completion within 3-6 weeksImmediate publication after the completion of final author proofreadDOI assignment for each published articleFree access to published articles for all readers without any access barriers or subscriptionThe views and opinions expressed in articles are those of the author/s and do not necessarily reflect the policies of the Journal of Proton Therapy.Authors are encouraged to submit articles for publication in the inaugural issue of the Journal of Proton Therapy by online or email to editor@protonjournal.comOfficial Website of Journal of Proton Therapy: http://www.protonjournal.org/

  19. Medical Proton Accelerator Project

    International Nuclear Information System (INIS)

    Comsan, M.N.H.

    2008-01-01

    A project for a medical proton accelerator for cancer treatment is outlined. The project is motivated by the need for a precise modality for cancer curing especially in children. Proton therapy is known by its superior radiation and biological effectiveness as compared to photon or electron therapy. With 26 proton and 3 heavy-ion therapy complexes operating worldwide only one (p) exists in South Africa, and none in south Asia and the Middle East. The accelerator of choice should provide protons with energy 75 MeV for eye treatment and 250 MeV for body treatment. Four treatment rooms are suggested: two with isocentric gantries, one with fixed beams and one for development. Passive scanning is recommended. The project can serve Middle East and North Africa with ∼ 400 million populations. The annual capacity of the project is estimated as 1,100 to be compared with expected radiation cases eligible for proton cancer treatment of not less than 200,000

  20. Proton relativistic model; Modelo relativistico do proton

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Wilson Roberto Barbosa de

    1996-12-31

    In this dissertation, we present a model for the nucleon, which is composed by three relativistic quarks interacting through a contract force. The nucleon wave-function was obtained from the Faddeev equation in the null-plane. The covariance of the model under kinematical null-plane boots is discussed. The electric proton form-factor, calculated from the Faddeev wave-function, was in agreement with the data for low-momentum transfers and described qualitatively the asymptotic region for momentum transfers around 2 GeV. (author) 42 refs., 22 figs., 1 tab.