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Sample records for 12c nucleus rezonansnye

  1. New experimental limits on the probabilities of pauli-forbidden transitions in the {sup 12}C nucleus from data obtained with the borexino detector

    SciTech Connect

    Derbin, A. V.; Fomenko, K. A.

    2010-12-15

    The Pauli exclusion principle was tested for nucleons in the {sup 12}C nucleus by using data from the Borexino detector. The approach used consisted in seeking photons, neutrons, and protons, as well as electrons and positrons, emitted in the Pauli-forbidden transitions of nucleons from the 1P{sub 3/2} shell to the filled 1S{sub 1/2} shell. Owing to a uniquely low background level in the Borexino detector and its large mass, the currently most stringent experimental limits were obtained for the probabilities and relative intensities of Pauli-forbidden transitions for the electromagnetic, strong, and weak channels.

  2. Phenomenological and semi-microscopic analysis for 16O and 12C elastically scattering on the nucleus of 16O and 12C at Energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Hamada, Sh; Burtebayev, N.; Amangeldi, N.; Gridnev, K. A.; Rusek, K.; Kerimkulov, Zh; Maltsev, N.

    2012-09-01

    The nuclear burning process proceeds from the conservation of the most abundant element hydrogen to helium, then from helium to carbon and oxygen, and then from these to heavier elements. Some of the key reactions for the carbon and oxygen burning stages of the nucleosynthesis are 12C+12C and 16O+16O leading to all possible final states. This paper contains the experimental measurements of 12C+12C and 16O+16O angular distributions performed at the cyclotron DC-60 in Astana, Kazakhstan. The extracted beam of 16O and 12C was accelerated up to two energies 1.75 and 1.5 MeV/n and then directed to an Al2O3 target of thickness 20 μg/cm2 and a carbon self-supporting target of thickness 17.4 μg/cm2. The angular distribution calculations were performed using both the phenomenological optical potential (SPI-GENOA) code and the double folding potential (FRESCO) code.

  3. Description of nuclear systems with a self-consistent configuration-mixing approach: Theory, algorithm, and application to the 12C test nucleus

    NASA Astrophysics Data System (ADS)

    Robin, C.; Pillet, N.; Peña Arteaga, D.; Berger, J.-F.

    2016-02-01

    Background: Although self-consistent multiconfiguration methods have been used for decades to address the description of atomic and molecular many-body systems, only a few trials have been made in the context of nuclear structure. Purpose: This work aims at the development of such an approach to describe in a unified way various types of correlations in nuclei in a self-consistent manner where the mean-field is improved as correlations are introduced. The goal is to reconcile the usually set-apart shell-model and self-consistent mean-field methods. Method: This approach is referred to as "variational multiparticle-multihole configuration mixing method." It is based on a double variational principle which yields a set of two coupled equations that determine at the same time the expansion coefficients of the many-body wave function and the single-particle states. The solution of this problem is obtained by building a doubly iterative numerical algorithm. Results: The formalism is derived and discussed in a general context, starting from a three-body Hamiltonian. Links to existing many-body techniques such as the formalism of Green's functions are established. First applications are done using the two-body D1S Gogny effective force. The numerical procedure is tested on the 12C nucleus to study the convergence features of the algorithm in different contexts. Ground-state properties as well as single-particle quantities are analyzed, and the description of the first 2+ state is examined. Conclusions: The self-consistent multiparticle-multihole configuration mixing method is fully applied for the first time to the description of a test nucleus. This study makes it possible to validate our numerical algorithm and leads to encouraging results. To test the method further, we will realize in the second article of this series a systematic description of more nuclei and observables obtained by applying the newly developed numerical procedure with the same Gogny force. As

  4. Non-coplanar compact configurations of nuclei and non-compound-nucleus contribution in the fusion cross section of the 12C+93Nb reaction

    NASA Astrophysics Data System (ADS)

    Chopra, Sahila; Hemdeep, Kaur, Arshdeep; Gupta, Raj K.

    2016-02-01

    Background: In our earlier study of the 12C+93Nb→*105Ag reaction at three near- and below-barrier energies (Ec .m .=41.097 , 47.828, and 54.205 MeV), using the dynamical cluster-decay model (DCM) with various nuclear interaction potentials (the Blocki et al. pocket formula and others derived from the Skyrme energy density formalism) for compact, coplanar (Φc=00 ) nuclei, we found a large non-compound-nucleus (nCN) contribution in the measured fusion cross section of this reaction. Purpose: In the present work, we look for the effect of using non-coplanar, compact configurations (Φc≠00 ), in the Blocki et al. pocket formula of the nuclear proximity potential, on the non-compound-nucleus (nCN) contribution, using the DCM. Methods: Allowing the Φ degree of freedom in the DCM formalism, we calculate the compound-nucleus (CN) and nCN cross sections. The only parameter of the DCM is the neck-length parameter Δ R , which also fits the empirically determined nCN cross section nearly exactly, under the assumption of considering it like a quasifission process where the fragment preformation factor P0=1 . Results: With the Φ degree of freedom included, at the higher two energies the nCN cross section gets enhanced, and hence the pure CN cross section is decreased, since the calculated (total) fusion cross section is fitted to experimental data. The parameter Δ R for the nCN contribution is smaller, and hence the reaction time larger, than for the CN decay process. Also, the contributing angular momentum ℓmax value increases in going from Φc=00 to Φc≠00 for both the CN and nCN processes. The intermediate mass fragments (IMFs), measured up to mass 13 in this reaction, are shown extended up to mass 16, and the fusion-fission (f f ) region is identified as A /2 ±16 , the same as for the Φc=00 case. Conclusions: As a result of enhanced nCN cross section due to Φc≠00 , the CN fusion probability PCN for *105Ag changes its behavior from an increasing to a

  5. Delta Electroproduction in 12-C

    SciTech Connect

    Steven McLauchlan

    2003-01-31

    The Delta-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the delta mass indicating that this potential is dependent on the momentum of the delta. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the delta resonance in 12C, performed using the high energy electron beam at the Thomas Jefferson National Accelerator Facility, and the near 4(pie) acceptance detector CLAS that enables the detection of the full reaction final state. Inclusive, semi inclusive, and exclusive cross sections were measured with an incident electron beam energy of 1.162GeV over the Q2 range 0.175-0.475 (GeV/c)2. A Q2 dependence of the delta mass was only observed in the exclusive measurements indicating that the delta-nucleus potential is affected by the momentum of the delta.

  6. Double folding cluster potential for {sup 12}C+{sup 12}C elastic scattering

    SciTech Connect

    Hassanain, M. A.; Ibraheem, Awad A.; Farid, M. El-Azab

    2008-03-15

    Using the alpha ({alpha})-cluster structure of {sup 12}C nucleus, two versions of the {sup 12}C+{sup 12}C real double folded optical potentials have been generated based upon effective {alpha}-{alpha},{alpha}-nucleon (N) and N-N interactions. The obtained potentials, in conjunction with shallow phenomenological Woods-Saxon imaginary parts, successfully reproduce the elastic scattering differential cross section for 12 sets of data over the broad energy range 70-360 MeV. No renormalization of the real folded potentials is required to fit the data. The energy dependence of the extracted real and imaginary volume integrals and total reaction cross section is investigated.

  7. Incoherent neutral pion photoproduction on 12C.

    PubMed

    Tarbert, C M; Watts, D P; Aguar, P; Ahrens, J; Annand, J R M; Arends, H J; Beck, R; Bekrenev, V; Boillat, B; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Codling, R; Downie, E J; Föhl, K; Glazier, D I; Grabmayr, P; Gregor, R; Heid, E; Hornidge, D; Jahn, O; Kashevarov, V L; Knezevic, A; Kondratiev, R; Korolija, M; Kotulla, M; Krambrich, D; Krusche, B; Lang, M; Lisin, V; Livingston, K; Lugert, S; Macgregor, I J D; Manley, D M; Martinez, M; McGeorge, J C; Mekterovic, D; Metag, V; Nefkens, B M K; Nikolaev, A; Novotny, R; Owens, R O; Pedroni, P; Polonski, A; Prakhov, S N; Price, J W; Rosner, G; Rost, M; Rostomyan, T; Schadmand, S; Schumann, S; Sober, D; Starostin, A; Supek, I; Thomas, A; Unverzagt, M; Walcher, Th; Zehr, F

    2008-04-01

    We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The 12C(gamma,pi(0))(12)C*(4.4 MeV) reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a pi(0) spectrometer and to detect decay photons from the excited residual nucleus. The technique has potential applications to a broad range of future nuclear measurements with the Crystal Ball and similar detector systems elsewhere. Such data are sensitive to the propagation of the Delta in the nuclear medium and will give the first information on matter transition form factors from measurements with an electromagnetic probe. The incoherent cross sections are compared to two theoretical predictions including a Delta-hole model. PMID:18517938

  8. High-spin molecular resonances in 12C + 12C

    NASA Astrophysics Data System (ADS)

    Uegaki, E.; Abe, Y.

    2016-05-01

    Resonances observed in the 12C + 12C collisions are studied with a molecular model. At high spins J = 10-18, a stable dinuclear configuration is found to be an equator-equator touching one. Firstly, normal modes have been solved around the equilibrium, with spin J and K-quantum number being specified for rotation of the whole system. Secondly, with respect to large centrifugal energy, Coriolis coupling has been diagonalized among low-lying 11 states of normal-mode excitations, which brings K-mixing. The analyses of decay widths and excitation functions have been done. The molecular ground state exhibits alignments of the orbital angular momentum and the 12C spins, while some of the molecular excited states exhibit disalignments with small widths. Those results are surprisingly in good agreement with the experiments, which will light up a new physical picture of the highspin 12C + 12C resonances.

  9. Angular correlation measurements for {sup 12}C{sup 12}C,{sup 12}C{sup 12}C 3{sup -} scattering

    SciTech Connect

    Wuosmaa, A.H.; Betts, R.R.; Freer, M.

    1995-08-01

    Previous studies of inelastic {sup 12}C + {sup 12}C scattering to a variety of final states identified significant resonance behavior in a number of different reaction channels. These resonances can be interpreted as either potential scattering resonances, or as population of cluster structures in the compound nucleus {sup 24}Mg, or as some interplay between the two mechanisms. Currently, for many of these resonances the situation remains unclear. One example is a large peak observed in the excitation function for the 3{sup -} - g.s. excitation, identified in previous work performed at the Daresbury Laboratory in England. This peak is observed at the same center-of-mass energy as one observed in the O{sub 2}{sup +}-O{sub 2}{sup +} inelastic scattering channel. That structure was suggested to correspond to exotic deformed configurations in the compound nucleus {sup 24}Mg. As the peak in the 3{sup -} + g.s. exit channel occurs at precisely the same energy as the purported resonance, it is tempting to associate the two. Before such an association can be confirmed or ruled out, further information must be obtained about the 3{sup -} + g.s. structure. In particular, it is important to determine the angular momenta that dominate the 3{sup -} + g.s. structure.

  10. YF-12C on ramp

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The so-called YF-12C on the NASA Flight Research Center ramp. Following the loss of a YF-12A in a non-fatal accident in June 1971, NASA acquired the second production SR-71A (61-7951) from the Air Force. Because the SR-71 program was shrouded in the highest secrecy, the Air Force restricted NASA to using the aircraft solely for propulsion testing with YF-12A inlets and engines. It was designated the YF-12C, and given a bogus tail number (06937). The two YF-12As in the program had actual tail numbers 06935 and 06936. The first NASA flight of the YF-12C took place on 24 May 1972. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 606936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse of the program, with 146 flights between 11 December 1969 and 7 November 1979. The second YF-12A, 936, made

  11. Incoherent Neutral Pion Photoproduction on {sup 12}C

    SciTech Connect

    Tarbert, C. M.; Watts, D. P.; Branford, D.; Foehl, K.; Glazier, D. I.; Aguar, P.; Ahrens, J.; Arends, H. J.; Heid, E.; Jahn, O.; Krambrich, D.; Martinez, M.; Rost, M.; Thomas, A.; Walcher, Th.; Annand, J. R. M.; Codling, R.; Downie, E. J.; Livingston, K.; MacGregor, I. J. D.

    2008-04-04

    We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The {sup 12}C({gamma},{pi}{sup 0}){sup 12}C{sub 4.4} {sub MeV}* reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a {pi}{sup 0} spectrometer and to detect decay photons from the excited residual nucleus. The technique has potential applications to a broad range of future nuclear measurements with the Crystal Ball and similar detector systems elsewhere. Such data are sensitive to the propagation of the {delta} in the nuclear medium and will give the first information on matter transition form factors from measurements with an electromagnetic probe. The incoherent cross sections are compared to two theoretical predictions including a {delta}-hole model.

  12. /sup 18/O + /sup 12/C fusion-evaporation reaction

    SciTech Connect

    Heusch, B; Beck, C; Coffin, J P; Freeman, R M; Gallmann, A; Haas, F; Rami, F; Wagner, P; Alburger, D E

    1980-01-01

    A study of the /sup 18/O + /sup 12/C fusion evaporation reaction has been undertaken for 2 reasons: to make a systematic study of the formation cross section for each individual evaporation residue over a broad excitation energy region in the compound nucleus /sup 30/Si:30 to 62 MeV; and to compare all results to fusion-evaporation calculations done in the framework of the Hauser-Feschbach statistical model.

  13. The C-12/C-13 abundance ratio in Comet Halley

    SciTech Connect

    Wyckoff, S.; Lindholm, E.; Wehinger, P.A.; Peterson, B.A.; Zucconi, J.M.

    1989-04-01

    The individual (C-13)N rotational lines in Comet Halley are resolved using high-resolution spectra of the CN B2Sigma(+)-X2Sigma(+) (0,0) band. The observe C-12/C-13 abundance ratio excludes a site of origin for the comet near Uranus and Neptune and suggests a condensation environment quite distinct from other solar system bodies. Two theories are presented for the origin of Comet Halley. One theory suggest that the comet originated 4.5 Gyr ago in an inner Oort cloud at a heliocentric distance greater than 100 AU where chemical fractionation led to the C-13 enrichment in the CN parent molecule prior to condensation of the comet nucleus. According to the other, more plausible theory, the comet nucleus condensed relatively recently from the interstellar medium which has become enriches in C-13 and was subsequently gravitationally captured by the solar system. 107 refs.

  14. The 12C* Hoyle state in the inelastic 12C + 12C reaction and in 24Mg* decay

    NASA Astrophysics Data System (ADS)

    Morelli, L.; Bruno, M.; D'Agostino, M.; Baiocco, G.; Gulminelli, F.; Abbondanno, U.; Barlini, S.; Bini, M.; Casini, G.; Cinausero, M.; Degerlier, M.; Fabris, D.; Gramegna, F.; Mabiala, J.; Marchi, T.; Olmi, A.; Pasquali, G.; Piantelli, S.; Valdré, S.

    2016-08-01

    The reaction 12C + 12C at 95 MeV has been studied at the Legnaro Laboratories of INFN with the GARFIELD + RCo apparatus. Data have been analyzed in order to investigate the decay of the Hoyle state of 12C*. Two different data selections have been made. The first one corresponds to peripheral binary collisions where the quasi-projectile is excited to the Hoyle state and the target has been left in the ground state. The second selection allows for studying central events with the formation of a 24Mg* and the Hoyle state is obtained as a step of the decay chain. The characteristics of the Hoyle state decay are very similar in the two samples and point to a mainly sequential decay through the population of an intermediate 8Begs, with a small contribution (˜1.1%) from simultaneous three α-particle processes.

  15. First direct measurement of 12C(12C,n)23Mg at stellar energies

    NASA Astrophysics Data System (ADS)

    Tang, X. D.; Bucher, B.; Fang, X.; Heger, A.; Almaraz-Calderon, S.; Alongi, A.; Ayangeakaa, A. D.; Beard, M.; Best, A.; Browne, J.; Cahillane, C.; Couder, M.; deBoer, R. J.; Kontos, A.; Lamm, L.; Li, Y. J.; Long, A.; Lu, W.; Lyons, S.; Notani, M.; Patel, D.; Paul, N.; Pignatari, M.; Roberts, A.; Robertson, D.; Smith, K.; Stech, E.; Talwar, R.; Tan, W. P.; Wiescher, M.; Woosley, S. E.

    2016-02-01

    Neutrons produced by the carbon fusion reaction 12C(12C,n)23Mg play an important role in stellar nucleosynthesis. Past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement which extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction 12C(12C,p)23Na. The new reaction rate has been determined with a well-defined uncertainty which exceeds the precision required by astrophysics models. Using our constrained rate, we find that 12C(12C,n)23Mg is crucial to the production of Na and Al in Pop-III Pair Instability Supernovae.

  16. Fusion measurements of 12C+12C at energies of astrophysical interest

    NASA Astrophysics Data System (ADS)

    Santiago-Gonzalez, D.; Jiang, C. L.; Rehm, K. E.; Alcorta, M.; Almaraz-Calderon, S.; Avila, M. L.; Ayangeakaa, A. D.; Back, B. B.; Bourgin, D.; Bucher, B.; Carpenter, M. P.; Courtin, S.; David, H. M.; Deibel, C. M.; Dickerson, C.; DiGiovine, B.; Fang, X.; Greene, J. P.; Haas, F.; Henderson, D. J.; Janssens, R. V. F.; Jenkins, D.; Lai, J.; Lauritsen, T.; Lefebvre-Schuhl, A.; Montanari, D.; Pardo, R. C.; Paul, M.; Seweryniak, D.; Tang, X. D.; Ugalde, C.; Zhu, S.

    2016-05-01

    The cross section of the 12C+12C fusion reaction at low energies is of paramount importance for models of stellar nucleosynthesis in different astrophysical scenarios, such as Type Ia supernovae and Xray superbursts, where this reaction is a primary route for the production of heavier elements. In a series of experiments performed at Argonne National Laboratory, using Gammasphere and an array of Silicon detectors, measurements of the fusion cross section of 12C+12C were successfully carried out with the γ and charged-particle coincidence technique in the center-of-mass energy range of 3-5 MeV. These were the first background-free fusion cross section measurements for 12C+12C at energies of astrophysical interest. Our results are consistent with previous measurements in the high-energy region; however, our lowest energy measurement indicates a fusion cross section slightly lower than those obtained with other techniques.

  17. Folding model calculations for 6He+12C elastic scattering

    NASA Astrophysics Data System (ADS)

    Awad, A. Ibraheem

    2016-03-01

    In the framework of the double folding model, we used the α+2n and di-triton configurations for the nuclear matter density of the 6He nucleus to generate the real part of the optical potential for the system 6He+12C. As an alternative, we also use the high energy approximation to generate the optical potential for the same system. The derived potentials are employed to analyze the elastic scattering differential cross section at energies of 38.3, 41.6 and 82.3 MeV/u. For the imaginary part of the potential we adopt the squared Woods-Saxon form. The obtained results are compared with the corresponding measured data as well as with available results in the literature. The calculated total reaction cross sections are investigated and compared with the optical limit Glauber model description.

  18. The 12C(12C,α)20Ne and 12C(12C,p)23Na reactions at the Gamow peak via the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Tumino, A.; Spitaleri, C.; Cherubini, S.; Guardo, L.; Gulino, M.; Indelicato, I.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Spartá, R.

    2016-05-01

    A measurement of the 12C(14N,α20Ne)2H and 12C(14N,p23Na)2Hreactions has been performed at a 14N beam energy of 30.0 MeV. The experiment aims to explore the extent to which contributing 24Mg excited states can be populated in the quasi-free reaction off the deuteron in 14N. In particular, the 24Mg excitation region explored in the measurement plays a key role in stellar carbon burning whose cross section is commonly determined by extrapolating high-energy fusion data. From preliminary results, α and proton channels are clearly identified. In particular, ground and first excited states of 20Ne and 23Na play a major role.

  19. Selective alpha particle decay of 12C+12C resonances to excited 20Ne rotational bands observed in the 12C(12C,α)20Ne reaction

    NASA Astrophysics Data System (ADS)

    Ledoux, R. J.; Ordon¯Ez, C. E.; Bechara, M. J.; Al-Juwair, H. A.; Lavelle, G.; Cosman, E. R.

    1984-09-01

    Excitation functions of the 12C(12C,α)20Ne reaction were measured at θlab=7.5° between Ec.m.=14-40 MeV and angular distributions were measured from Ec.m.=17.8 to 20.6 MeV. Summed yields reveal prominent intermediate structure resonances over the entire range which correlate well to resonances previously observed in elastic data. The resonances show enhanced decays to excited rotational bands in 20Ne with reduced widths comparable to those for the elastic channel and an order of magnitude greater than those for the 20Ne ground state band. A discussion is given of the resonances as shape-isomeric states in a shell model secondary minimum in 24Mg, and of the selective alpha decay as being transitions to states of related configuration in 20Ne.

  20. First Direct Measurement of (12)C((12)C,n)(23)Mg at Stellar Energies.

    PubMed

    Bucher, B; Tang, X D; Fang, X; Heger, A; Almaraz-Calderon, S; Alongi, A; Ayangeakaa, A D; Beard, M; Best, A; Browne, J; Cahillane, C; Couder, M; deBoer, R J; Kontos, A; Lamm, L; Li, Y J; Long, A; Lu, W; Lyons, S; Notani, M; Patel, D; Paul, N; Pignatari, M; Roberts, A; Robertson, D; Smith, K; Stech, E; Talwar, R; Tan, W P; Wiescher, M; Woosley, S E

    2015-06-26

    Neutrons produced by the carbon fusion reaction (12)C((12)C,n)(23)Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction (12)C((12)C,p)(23)Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that (12)C((12)C,n)(23)Mg is crucial to the production of Na and Al in pop-III pair instability supernovae. It also plays a nonnegligible role in the production of weak s-process elements, as well as in the production of the important galactic γ-ray emitter (60)Fe. PMID:26197115

  1. Multicluster study of the {sup 12}C+n and {sup 12}C+p systems

    SciTech Connect

    Dufour, M.; Descouvemont, P.; Dufour, M.

    1997-10-01

    We use the generator coordinate method to study the {sup 12}C( n,{gamma}){sup 13}C and {sup 12}C( p,{gamma}){sup 13}N reactions, as well as the {sup 13}C and {sup 13}N spectroscopy. The {sup 12}C wave functions are defined by three {alpha} particles in a regular triangle of size R{sub C}. Different configurations are considered, in order to analyze clustering effects. It is shown that spectroscopic properties of {sup 13}C and {sup 13}N are sensitive to the {sup 12}C wave function; reasonable agreement with experiment is found with R{sub C} values minimizing the {sup 12}C binding energy. The present study supports the suggestion of a halo structure for the 1/2{sup +} excited state in {sup 13}C. The neutron and proton capture cross sections are in good agreement with experiment. Finally, we analyze distortion effects in the {sup 12}C+n wave functions. {copyright} {ital 1997} {ital The American Physical Society}

  2. The Circumstellar Shell of the Post-Asymptotic Giant Branch Star HD 56126: 12C12C/12C13C Isotope Ratio and 12C16O Column Density

    NASA Astrophysics Data System (ADS)

    Bakker, Eric J.; Lambert, David L.

    1998-11-01

    We have made the first detection of circumstellar absorption lines of the 12C13C A 1Πu-X 1Σ+g (Phillips) system 1-0 band and the 12C16O X 1Σ+ first-overtone 2-0 band in the spectrum of the post-AGB star HD 56126 (IRAS 07134+1005). All current detections of circumstellar molecular absorption lines toward HD 56126 (12C2, 12C13C, 12C14N, 13C14N, and 12C16O) yield the same heliocentric velocity of VCSE = 77.6 +/- 0.4 km s-1. The 12C2, 12C13C, and 12C16O lines give rotational temperatures and integrated column densities of Trot = 328 +/- 37 K, log Nint = 15.34 +/- 0.10 cm-2, Trot = 256 +/- 30 K, log Nint = 13.79 +/- 0.12 cm-2, and Trot = 51 +/- 37 K, log Nint = 18.12 +/- 0.13 cm-2, respectively. The rotational temperatures are lower for molecules with a higher permanent dipole moment. Derived relative column densities ratios are 12C2/12C13C = 36 +/- 13 and 12C16O/(12C2 + 12C13C) = 606 +/- 230. Combined with data from a previous paper, we find relative column densities of 12C16O/(12C14N + 13C14N) = 475 +/- 175 and 12C14N/13C14N = 38 +/- 2. Under chemical equilibrium conditions, 12C13C is formed twice as easily as 12C2. The isotopic exchange reaction for 12C2 is too slow to significantly alter the 12C2/12C13C ratio, and the 12C2 to 12C13C ratio is a good measure of half the carbon isotope ratio: 12C/13C = 2 × 12C2/12C13C = 72 +/- 26. This is in agreement with our prediction that the isotopic exchange reaction for 12C14N is efficient and our observation in Paper III of 12C14N/13C14N = 38 +/- 2. A fit of the C2 excitation model of van Dishoeck & Black to the relative population distribution of C2 yields nc σ/I = 3.3 +/- 1.0 × 10-14. At r ~= 1016 cm, this translates into nc = 1.7 × 107 cm-3 and Ṁ~=2.5×10-4 M⊙ yr-1.

  3. YF-12C in flight at sunset

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The so-called YF-12C in flight at sunset. The YF-12C was the second production SR-71A (61-7951), modified with YF-12A inlets and engines, and given a bogus tail number (06937). It replaced a YF-12A (60-6936) that crashed during a joint USAF-NASA research program. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 60-6936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse of the program, with 146 flights between 11 December 1969 and 7 November 1979. The second YF-12A, 936, made 62 flights. It was lost in a non-fatal crash on 24 June 1971. It was replaced by the YF-12C. The YF-12C was delivered to NASA on 16 July 1971. From then until 22 December 1978, it made 90 flights. The Lockheed A-12 family, known as the Blackbirds, were designed by Clarence 'Kelly' Johnson. They were constructed mostly

  4. Spin alignment and density matrix measurement in sup 28 Si + sup 12 C orbiting reaction

    SciTech Connect

    Ray, A.; Shapira, D.; Halbert, M.L.; Gomez del Campo, J.; Kim, H.J. ); Sullivan, J.P. . Cyclotron Inst.); Shivakumar, B.; Mitchell, J. . Wright Nuclear Structure Lab.)

    1990-01-01

    Gamma-ray angular correlations have been measured for the strongly damped reactions {sup 12}C({sup 28}Si,{sup 12}C){sup 28}Si between {theta}{sub cm} = (120{degree} {minus} 160{degree}) for E{sub cm} = 43.5 and 48 MeV. We find that the density matrices for the {sup 12}C(2{sub 1}{sup +}) and {sup 28}Si states are almost diagonal with respect to the direction of motion of the outgoing particle. The measured density matrices and spin alignments are consistent with the picture of formation of a long-lived dinuclear complex undergoing orbiting, bending and wriggling motions, but not with those obtained from statistical compound nucleus or sticking model calculations. 17 refs., 2 figs., 1 tab.

  5. 12C+ 12C elastic scattering excitation functions and phase shift analysis

    NASA Astrophysics Data System (ADS)

    Ledoux, R. J.; Bechara, M. J.; Ordonez, C. E.; Al-Juwair, H. A.; Cosman, E. R.

    1983-03-01

    The 12C+ 12C elastic scattering has been measured for Ec.m.=14.6-31.3 MeV, θc.m.=30°-110°. The elastic data have been analyzed via a phase shift analysis, enabling the extraction of model independent sets of phase shift parameters. The extracted Jπ values for the intermediate structure resonances at Ec.m.=18.4, 19.3, and 20.3 MeV are 12+, 12+, and 12+ or 14+, respectively. The questions of ambiguities in the phase shift analysis and the comparison with Jπ values deduced from other experiments are discussed. Evidence is presented for the existence of gross structure resonances. The elastic scattering has also been analyzed using the sum-of-differences method to directly extract the total reaction cross section. The results of these analyses are compared to existing models of the origin of intermediate structure resonances. NUCLEAR REACTIONS Measured the 12C+ 12C elastic scattering, Ec.m.=14.6-31.3 MeV, θc.m.=30°-110°. Phase shift analysis, sum-of-differences analysis.

  6. Decay strength distributions in {sup 12}C({sup 12}C,{gamma}) radiative capture

    SciTech Connect

    Jenkins, D. G.; Fulton, B. R.; Marley, P.; Fox, S. P.; Glover, R.; Wadsworth, R.; Watson, D. L.; Courtin, S.; Haas, F.; Lebhertz, D.; Beck, C.; Papka, P.; Rousseau, M.; Sanchez i Zafra, A.; Hutcheon, D. A.; Davis, C.; Ottewell, D.; Pavan, M. M.; Pearson, J.; Ruiz, C.

    2007-10-15

    The heavy-ion radiative capture reaction, {sup 12}C({sup 12}C,{gamma}), has been investigated at energies both on- and off-resonance, with a particular focus on known resonances at E{sub c.m.}=6.0, 6.8, 7.5, and 8.0 MeV. Gamma rays detected in a BGO scintillator array were recorded in coincidence with {sup 24}Mg residues at the focal plane of the DRAGON recoil separator at TRIUMF. In this manner, the relative strength of all decay pathways through excited states up to the particle threshold could be examined for the first time. Isovector M1 transitions are found to be a important component of the radiative capture from the E{sub c.m.}=6.0 and 6.8 MeV resonances. Comparison with Monte Carlo simulations suggests that these resonances may have either J=0 or 2, with a preference for J=2. The higher energy resonances at E{sub c.m.}=7.5 and 8.0 MeV have a rather different decay pattern. The former is a clear candidate for a J=4 resonance, whereas the latter has a dominant J=4 character superposed on a J=2 resonant component underneath. The relationship between these resonances and the well-known quasimolecular resonances as well as resonances in breakup and electrofission of {sup 24}Mg into two {sup 12}C nuclei are discussed.

  7. Measurement of the ^12C+^12C Fusion Reaction with MUSIC

    NASA Astrophysics Data System (ADS)

    Carnelli, P. F. F.; Almaraz-Calderon, S.; Henderson, D.; Rehm, K. E.; Albers, M.; Alcorta, M.; Bertone, P. F.; Esbensen, H.; Fernandez-Niello, J. O.; Jiang, C. L.; Lighthall, J. C.; Marley, S. T.; Palchan-Hazan, T.; Pardo, R. C.; Paul, M.

    2012-10-01

    The fusion of the ^12C+^12C system is of great interest in nuclear structure and nuclear astrophysics. Above the Coulomb barrier, the excitation function of this system exhibits oscillations, which are not well understood. There is also a significant discrepancy between the experimental fusion cross-section and recent coupled-channel calculations that is not present in other carbon systems. To address these issues, we have re-measured the fusion excitation function for ^12,13C+^12C in the energy range of 10 MeV < Ecm < 20 MeV using a Multi-Sampling Ionization Chamber (MUSIC) detector. The gas of the ionization chamber (CH4) served as both the target material and the counter gas. One of the main advantages of this method is that the excitation function is measured over a large range of energies using only one beam energy. This method has been proven to be successful and it will be used to measure fusion reactions in other light systems. The experimental results will be presented and compared to previous experimental data and theoretical models.

  8. Solving the {sup 12}C+{sup 12}C scattering puzzle: is there the '4th elephant'?

    SciTech Connect

    Demyanova, A. S.; Danilov, A. N.; Ogloblin, A. A.; Goncharov, S. A.; Bohlen, H. G.; Khlebnikov, S. V.; Tyurin, G. P.; Maslov, V. A.; Penionzkevich, Yu. E.; Sobolev, Yu. G.; Trzaska, W.

    2010-04-30

    Differential cross sections of the {sup 12}C+{sup 12}C and the {sup 13}C+{sup 12}C elastic scattering were measured at the projectile energies 240 MeV ({sup 12}C) and 250 MeV ({sup 13}C) up to the largest angles. The positions of the 1{sup st} Airy minima known from the former experiments were confirmed.

  9. Investigation of multiparticle final states in {sup 12}C photoreactions

    SciTech Connect

    Harty, P.D.; MacGregor, I.J.; Annand, J.R.; Anthony, I.; Cross, G.E.; Hall, S.J.; Kellie, J.D.; McGeorge, J.C.; Miller, G.J.; Owens, R.O.; Grabmayr, P.; Hehl, T.; Lamparter, T.; Sauer, M.; Schneider, R.; Spaeth, K.; Branford, D.; Davinson, T.; MacKenzie, J.A.; Ahrens, J.; Beck, R.

    1998-01-01

    The {sup 12}C({gamma},pn), {sup 12}C({gamma},pp), {sup 12}C({gamma},ppp), {sup 12}C({gamma},pp{pi}{sup {plus_minus}}), {sup 12}C({gamma},p{pi}{sup {plus_minus}}) reactions have been studied using tagged photons of energy E{sub {gamma}}=250{endash}600 MeV. A model which includes all major absorption mechanisms and final state interactions gives results that agree well with the shapes of missing energy spectra, but for some channels the predicted cross sections are too large. {copyright} {ital 1998} {ital The American Physical Society}

  10. Investigation of proton-proton short-range correlations via the 12C(e,e'pp) reaction.

    PubMed

    Shneor, R; Monaghan, P; Subedi, R; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertin, P; Bertozzi, W; Boeglin, W; Chen, J P; Choi, Seonho; Chudakov, E; Cisbani, E; Craver, B; de Jager, C W; Feuerbach, R J; Frullani, S; Garibaldi, F; Gayou, O; Gilad, S; Gilman, R; Glamazdin, O; Gomez, J; Hansen, J-O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; Jans, E; Jiang, X; Jiang, Y; Kaufman, L; Kelleher, A; Kolarkar, A; Kuchina, E; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Nanda, S; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Reitz, B; Ron, G; Rosner, G; Saha, A; Sawatzky, B; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Thompson, N; Ulmer, P E; Urciuoli, G M; Voutier, E; Wang, K; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Yao, H; Zheng, X; Zhu, L

    2007-08-17

    We investigated simultaneously the 12C(e,e'p) and 12C(e,e'pp) reactions at Q2=2 (GeV/c)2, xB=1.2, and in an (e, e'p) missing-momentum range from 300 to 600 MeV/c. At these kinematics, with a missing momentum greater than the Fermi momentum of nucleons in a nucleus and far from the delta excitation, short-range nucleon-nucleon correlations are predicted to dominate the reaction. For (9.5+/-2)% of the 12C(e,e'p) events, a recoiling partner proton was observed back-to-back to the 12C(e,e'p) missing-momentum vector, an experimental signature of correlations. PMID:17930888

  11. Investigation of Proton-Proton Short-Range Correlations via the 12C(e,e'pp) Reaction

    SciTech Connect

    J. Arrington; H. Benaoum; F. Benmokhtar; P. Bertin; W. Bertozzi; W. Boeglin; J. P. Chen; Seonho Choi; E. Chudakov; E. Cisbani; B. Craver; C. W. de Jager; R. Feuerbach; S. Frullani; F. Garibaldi; O. Gayou; S. Gilad; R. Gilman; O. Glamazdin; J. Gomez; O. Hansen; D. W. Higinbotham; T. Holmstrom; H. Ibrahim; R. Igarashi; E. Jans; X. Jiang; Y. Jiang; L. Kaufman; A. Kelleher; A. Kolarkar; E. Kuchina; G. Kumbartzki; J. J. LeRose; R. Lindgren; N. Liyanage; D. J. Margaziotis; P. Markowitz; S. Marrone; M. Mazouz; R. Michaels; B. Moffit; S. Nanda; C. F. Perdrisat; E. Piasetzky; M. Potokar; V. Punjabi; Y. Qiang; J. Reinhold; B. Reitz; G. Ron; G. Rosner; A. Saha; B. Sawatzky; A. Shahinyan; S. Sirca; K. Slifer; P. Solvignon; V. Sulkosky; N. Thompson; P. E. Ulmer; G. M. Urciuoli; E. Voutier; K. Wang; J. W. Watson

    2007-08-01

    We investigated simultaneously the 12C(e,e'p) and 12C(e,e'pp) reactions at Q2 = 2 [GeV/c]2, x_B = 1.2, and in an (e,e'p) missing-momentum range from 300 to 600 MeV/c. At these kinematics, with a missing-momentum greater than the Fermi momentum of nucleons in a nucleus and far from the delta excitation, short-range nucleon-nucleon correlations are predicted to dominate the reaction. For(9.5 +/- 2)% of the 12C(e,e'p) events, a recoiling partner proton was observed back-to-back to the 12C(e,e'p) missing momentum vector, an experimental signature of correlations.

  12. The effect of 12C + 12C rate uncertainties on the weak s-process component

    SciTech Connect

    Fryer, Christopher Lee; Hungerford, Aimee L; Hirschi, Raphael; Pignatari, Marco; Bennett, Michael E; Diehl, Steven; Herwig, Falk; Hillary, William; Richman, Debra; Rockefeller, Gabriel; Timmes, Frank X; Wiescher, Michael

    2010-09-10

    The contribution by massive stars (M > 15M{sub {circle_dot}}) to the weak s-process component of the solar system abundances is primarily due to the {sup 22}Ne neutron source, which is activated near the end of helium-core burning. The residual {sup 22}Ne left over from helium-core burning is then reignited during carbon burning, initiating further s-processing that modifies the isotopic distribution. This modification is sensitive to the stellar structure and the carbon burning reaction rate. Recent work on the {sup 12}C + {sup 12}C reaction suggests that resonances located within the Gamow peak may exist, causing a strong increase in the astrophysical S-factor and consequently the reaction rate. To investigate the effect of such a rate, 25M{sub {circle_dot}} stellar models with different carbon burning rates, at solar metallicity, were generated using the Geneva Stellar Evolution Code (GENEC) with nucleosynthesis post-processing calculated using the NuGrid Multi-zone Post-Processing Network code (MPPNP). A strongly enhanced rate can cause carbon burning to occur in a convective core rather than a radiative one and the convective core mixes the matter synthesized there up into the carbon shell, significantly altering the initial composition of the carbon-shell. In addition, an enhanced rate causes carbon-shell burning episodes to ignite earlier in the evolution of the star, igniting the {sup 22}Ne source at lower temperatures and reducing the neutron density.

  13. Semiclassical description of the {sup 6}He+{sup 12}C elastic scattering

    SciTech Connect

    Bayrak, O. Boztosun, I.

    2011-01-15

    The results of the elastic scattering of {sup 6}He+{sup 12}C systemat E{sub Lab} = 18 MeV by using the barrier and internal wave decomposition of the S-matrix element within the framework of the WKB method are presented. This is the first detailed study for the interaction of the exotic {sup 6}He nucleus on different stable nuclei by using a semiclassicalmethod. In this paper, we show that in order to obtain the elastic scattering cross section of the {sup 6}He+{sup 12}C systemat energies close to the Coulomb barrier, it is vitally important to take into account the inner complex turning points in the calculations and the tunneling effects play a crucial role to explain the experimental data. The semiclassical results are compared with the experimental data as well as the quantum-mechanical one.

  14. Nuclear transparency and the onset of strong absorption regime in the 12C+24Mg system

    NASA Astrophysics Data System (ADS)

    Lichtenthäler, R.; Lépine-Szily, A.; Hussein, M. S.

    1999-10-01

    The elastic scattering of 12C+24Mg has been studied by means of a phase-shift analysis of 21 angular distributions ranging from Elab=16 MeV up to Elab=40 MeV. A tridimensional plot of the reflection coefficient of the S matrix as a function of the angular momentum and energy shows a well-defined region of energy, which separates two regimes: strong absorption for higher energies and the so-called ``anomalous transparency regime,'' recently observed in this system at low energies. The Argand diagrams of the S matrix in angular momentum space also present very contrasting behaviors in the two regions with very rapidly varying phases in the low energy region, which we associate with a parity dependent term in the S matrix directly related to significant coupling to the elastic transfer of a 12C nucleus.

  15. Simulation of 12C+12C elastic scattering at high energy by using the Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Guo, Chen-Lei; Zhang, Gao-Long; Tanihata, I.; Le, Xiao-Yun

    2012-03-01

    The Monte Carlo method is used to simulate the 12C+12C reaction process. Taking into account the size of the incident 12C beam spot and the thickness of the 12C target, the distributions of scattered 12C on the MWPC and the CsI detectors at a detective distance have been simulated. In order to separate elastic scattering from the inelastic scattering with 4.4 MeV excited energy, we set several variables: the kinetic energy of incident 12C, the thickness of the 12C target, the ratio of the excited state, the wire spacing of the MWPC, the energy resolution of the CsI detector and the time resolution of the plastic scintillator. From the simulation results, the preliminary establishment of the experiment system can be determined to be that the beam size of the incident 12C is phi5 mm, the incident kinetic energy is 200-400 A MeV, the target thickness is 2 mm, the ratio of the excited state is 20%, the flight distance of scattered 12C is 3 m, the energy resolution of the CsI detectors is 1%, the time resolution of the plastic scintillator is 0.5%, and the size of the CsI detectors is 7 cm×7 cm, and we need at least 16 CsI detectors to cover a 0° to 5° angular distribution.

  16. {sup 12}C+{sup 12}C reactions at astrophysical energies: Tests of targets behaviour under beam bombardment

    SciTech Connect

    Morales-Gallegos, L.; Aliotta, M.; Davinson, T.; Di Leva, A.; Imbriani, G.; Romano, M.; Romoli, M.; Gialanella, L.; Schürmann, D.; De Cesare, M.; Strieder, F.

    2014-05-09

    {sup 12}C({sup 12}C,α){sup 20}Ne and {sup 12}C({sup 12}C,p){sup 23}Na are the most important reactions during the carbon burning phase in stars. Direct measurements at the relevant astrophysical energy (E=1.5±0.3MeV) are very challenging because of the extremely small cross sections involved and of the high beam-induced background originating from impurities in the targets. In addition, persistent resonant structures at low energies are not well understood and make the extrapolation of the cross section from high energy data very uncertain. As a preliminary step towards the measurements of the {sup 12}C({sup 12}C,α){sup 20}Ne and {sup 12}C({sup 12}C,p){sup 23}Na reactions we intend to investigate the behaviour of targets under beam bombardment, specifically the quantitative measurement of hydrogen and deuterium content of highly pure stable carbon targets in relation to target temperature. Experiments are taking place at the CIRCE accelerator in Caserta, Italy and preliminary results are presented here.

  17. Deformation and cluster structures in 12C studied with configuration mixing using Skyrme interactions

    NASA Astrophysics Data System (ADS)

    Fukuoka, Y.; Shinohara, S.; Funaki, Y.; Nakatsukasa, T.; Yabana, K.

    2013-07-01

    We report an investigation of the structure of the 12C nucleus employing a newly developed configuration-mixing method. In the three-dimensional coordinate-space representation, we generate a number of Slater determinants with various correlated structures using the imaginary-time algorithm. We then diagonalize a many-body Hamiltonian with the Skyrme interaction in the space spanned by the Slater determinants with parity and angular momentum projections. Our calculation reasonably describes the ground and excited states of the 12C nucleus, both for shell-model-like and cluster-like states. The excitation energies and transition strengths of the ground-state rotational band are well reproduced. Negative-parity excited states, 11-, 21-, and 31-, are also reasonably described. The second and third 0+ states, 02+ and 03+, appear at around 8.8 and 15 MeV, respectively. The 02+ state shows a structure consistent with former results of the α-cluster models. However, the calculated radius of the 02+ state is smaller than in those calculations. The three-α linear-chain configuration dominates in the 03+ state.

  18. Hyperdeformed band in 36Ar populated in the 12C + 24Mg elastic scattering

    NASA Astrophysics Data System (ADS)

    Lépine-Szily, A.; Sciani, W.; Benjamim, E. A.; Chamon, L. C.; Lichtenthäler, R.; Otani, Y.

    2008-05-01

    The strongly oscillating angular distributions of the elastic scattering of 12C + 24Mg at energies around the Coulomb barrier (Ecm = 10.67 - 16.00 MeV) [1] were reproduced adding three Breit-Wigner resonance terms with J values of 6, 7 and 8 h respectively to the l = 6, 7 and 8 terms of the elastic S-matrix. The elastic scattering S-matrix was calculated using the double folding, deep, optical potential with non-local interaction, also called, Sao Paulo Potential [2]. All fifteen angular distributions could be well reproduced by the 3 resonances, located respectively at Ecm = 14.15, 15.8 and 16.9 MeV in the entrance channel, which correspond to excitation energies of 30.45, 32.1 and 33.2 MeV in the 36Ar compound nucleus. The J = 6, 7 and 8 h resonances fit well into a rotational molecular band, together with the J = 18, 20, 22 and 24 h resonances observed in the 16O + 20Ne elastic scattering [3]. The band head is at 29.5 MeV excitation energy in the 36Ar compound nucleus and has a large moment of inertia indicating a large deformation. Calculations of Rae and Merchant [4] propose the existence of a hyperdeformed band in 36Ar with 12C + 24Mg and 16O + 20Ne cluster structure.

  19. Detailed study for 16O → 12C + α and 12C → 11B + p spectroscopic factors

    NASA Astrophysics Data System (ADS)

    Hamada, Sh.; Burtebayev, N.; Amangeldi, N.

    2014-10-01

    We have measured the angular distributions for 16O elastically scattered on 12C nuclei at energy 28 MeV and also for 12C ion beam elastically scattered on 11B target nuclei at energy 18 MeV. These measurements were performed in the cyclotron DC-60 INP NNC RK. Calculations were performed using both empirical Woods-Saxon and double folding optical model potentials. Both elastic scattering and transfer reaction were taken into consideration. We have extracted the spectroscopic factors for the configurations 16O → 12C + α and 12C → 11B + p and compared them with other calculated or extracted values at different energies from literature. The extracted spectroscopic factor for the configuration 12C → 11B + p from the current work is in the range 2.7-3.1, which is very close to Cohen-Kurath prediction. While for the configuration 16O → 12C + α, spectroscopic factors show fluctuation with energy which could be due to the well-known resonant-like behavior observed in 16O + 12C excitation function.

  20. Preequilibrium processes in the fusion of {sup 12}C with {sup 103}Rh up to 20 MeV/nucleon

    SciTech Connect

    Birattari, C.; Bonardi, M.; Cavinato, M.; Fabrici, E.; Gadioli, E.; Gadioli Erba, E.; Groppi, F.; Bello, M.; Bovati, C.; Di Filippo, A. |; Stevens, T.G.; Connell, S.H.; Sellschop, J.P.; Mills, S.J.; Nortier, F.M.; Steyn, G.F.; Marchetta, C. |

    1996-12-01

    We have measured the excitation functions of several reactions occurring in the fusion of {sup 12}C with {sup 103}Rh at incident energies up to about 230 MeV. The data can be satisfactorily reproduced by considering the preequilibrium emission of particles during the thermalization of the composite nucleus. The energy evolution of the mean-field interaction is also discussed. {copyright} {ital 1996 The American Physical Society.}

  1. Neutrino and antineutrino charge-exchange reactions on {sup 12}C

    SciTech Connect

    Samana, A. R.; Krmpotic, F.; Paar, N.; Bertulani, C. A.

    2011-02-15

    We extend the formalism of weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, for both neutrino-nucleus reactions and muon capture. Explicit violation of the conserved vector current hypothesis by the Coulomb field, as well as development of a sum-rule approach for inclusive cross sections, has been worked out. We have done a thorough study of exclusive (ground-state) properties of {sup 12}B and {sup 12}N within the projected quasiparticle random phase approximation (PQRPA). Good agreement with experimental data achieved in this way put into evidence the limitations of the standard RPA and QRPA models, which come from the inability of the RPA to open the p{sub 3/2} shell and from the nonconservation of the number of particles in the QRPA. The inclusive neutrino/antineutrino ({nu}/{nu}-tilde) reactions {sup 12}C({nu},e{sup -}){sup 12}N and {sup 12}C({nu}-tilde,e{sup +}){sup 12}B are calculated within both the PQRPA and the relativistic QRPA. It is found that (i) the magnitudes of the resulting cross sections are close to the sum-rule limit at low energy, but significantly smaller than this limit at high energies, for both {nu} and {nu}-tilde; (ii) they increase steadily when the size of the configuration space is augmented, particularly for {nu}/{nu}-tilde energies >200 MeV; and (iii) they converge for sufficiently large configuration space and final-state spin. The quasi-elastic {sup 12}C({nu},{mu}{sup -}){sup 12}N cross section recently measured in the MiniBooNE experiment is briefly discussed. We study the decomposition of the inclusive cross section based on the degree of forbiddenness of different multipoles. A few words are dedicated to the {nu}/{nu}-tilde-{sup 12}C charge-exchange reactions related to astrophysical applications.

  2. Terahertz Spectroscopy of the Bending Vibrations of Acetylene 12C2H2 and 12C2D2

    NASA Astrophysics Data System (ADS)

    Yu, Shanshan; Drouin, B.; Pearson, J.

    2009-12-01

    Several fundamental interstellar molecules, e.g., C2H2, CH4 and C3, are completely symmetric molecules and feature no permanent dipole moment and no pure rotation spectrum. As a result they have only previously been observed in the infrared. However, directly observing them with the rest of the molecular column especially when the source is spatially resolved would be very valuable in understanding chemical evolution. Vibrational difference bands provide a means to detect symmetric molecules with microwave precision using terahertz techniques. Herschel, SOFIA and ALMA have the potential to identify a number of vibrational difference bands of light symmetric species. This paper reports laboratory results on 12C2H2 and 12C2D2. Symmetric acetylene isotopologues have two bending modes, the trans bending and the cis bending. Their difference bands are allowed and occur in the microwave, terahertz, and far-infrared wavelengths, with band origins at 3500 GHz for 12C2H2 and 900 GHz for 12C2D2. Twenty 12C2H2 P branch high-J transitions and two hundred and fifty-one 12C2D2 P Q and R branch transitions have been measured in the 0.2 - 1.6 THz region with precision of 50 to 100 kHz. These lines were modeled together with prior data on the pure bending levels. Significantly improved molecular parameters were obtained for 12C2H2 and 12C2D2 with the combined data set, and new frequency and intensity predictions were made to support astrophysics applications. The research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. S. Y. was supported by an appointment to the NASA Postdoctoral Program, administrated by Oak Ridge Associated Universities through a contract with NASA.

  3. The C-12/C-13 Ratio as a Chemistry Indicator

    NASA Technical Reports Server (NTRS)

    Wirstroem, Eva; Geppert, Wolf; Persson, Carina; Charnley, Steven

    2011-01-01

    Isotopic ratios of elements are considered powerful tools, e.g. in tracing the origin of solar system body materials, or the degree of nucleosynthesis processing throughout the Galaxy. In interstellar molecules, some isotopic ratios like H/D and C-12/C-13 can also be used as indicators of their chemical origin. Isotope fractionation in gas-phase chemical reactions and gas-dust interaction makes observations of the ratio between C-12 and C-13 isotopologues suitable to distinguish between different formation scenarios. We will present observations of the C-12/C-13 ratio in methanol and formaldehyde towards a sample of embedded, massive young stellar objects. In relation to this we also present results from theoretical modeling showing the usefulness of the C-12/C-13 ratio as a chemistry indicator.

  4. Reexamination of the excited states of {sup 12}C

    SciTech Connect

    Freer, M.; Munoz-Britton, T.; Nicoli, M. P.; Singer, S. M.; Sparks, N.; Boztosun, I.; Bremner, C. A.; Chappell, S. P. G.; Rae, W. D. M.; Cowin, R. L.; Dillon, G. K.; Fulton, B. R.; Greenhalgh, B. J.; Watson, D. L.; Weisser, D. C.

    2007-09-15

    An analysis of the {sup 12}C({sup 12}C,3{alpha}){sup 12}C reaction was made at beam energies between 82 and 106 MeV. Decays to both the ground state and the excited states of {sup 8}Be were isolated, allowing states of different characters to be identified. In particular, evidence was found for a previously observed state at 11.16 MeV. An analysis of the angular distributions of the unnatural parity states at 11.83 and 13.35 MeV, previously assigned J{sup {pi}}=2{sup -}, calls into question the validity of these assignments, suggesting that at least one of the states may correspond to J{sup {pi}}=4{sup -}. Evidence is also found for 1{sup -} and 3{sup -} strengths associated with broad states between 11 and 14 MeV.

  5. EFOM 12C software: general overview. Final report

    SciTech Connect

    Jadot, P.; Fuchsova, J.; Vankelecom, E.; Van der Voort, E.; Thonet, C.

    1981-01-01

    The EFOM EC-12C software is described, produced by Systems-Europe during the first program of the CEC on energy modelling. This includes DAMOCLES, a specific data-base management system; SIMUL, a simulation program whose prime function is to check data consistency and issue warning messages when inconsistencies occur; and ORESTE-EDISON, a linear program matrix generator and report writer. The energy model, and the method of representing the energy system are briefly described. Appendix A defines the parameters needed to perform the case studies using the EFOM 12C software.

  6. Electromagnetic Response of ^{12}C: A First-Principles Calculation.

    PubMed

    Lovato, A; Gandolfi, S; Carlson, J; Pieper, Steven C; Schiavilla, R

    2016-08-19

    The longitudinal and transverse electromagnetic response functions of ^{12}C are computed in a "first-principles" Green's function Monte Carlo calculation, based on realistic two- and three-nucleon interactions and associated one- and two-body currents. We find excellent agreement between theory and experiment and, in particular, no evidence for the quenching of the measured versus calculated longitudinal response. This is further corroborated by a reanalysis of the Coulomb sum rule, in which the contributions from the low-lying J^{π}=2^{+}, 0_{2}^{+} (Hoyle), and 4^{+} states in ^{12}C are accounted for explicitly in evaluating the total inelastic strength. PMID:27588850

  7. Cluster Structure of {sup 12}C and {sup 11}Be

    SciTech Connect

    Freer, M.; Haigh, P. J.; Ashwood, N. I.; Bloxham, T.; Curtis, N.; McEwan, P.; Fujita, H.; Carter, J.; Usman, I.; Buthelezi, Z.; Foertsch, S. V.; Neveling, R.; Perez, S. M.; Smit, F. D.; Fearick, R. W.; Papka, P.; Swartz, J. A.; Bohlen, H. G.; Dorsch, T.; Kokalova, Tz.

    2009-08-26

    The structure of {sup 12}C is discussed, in particular the spectrum of states above the alpha-decay threshold. A search for the 2{sup +} excitation of the Hoyle-state is reported. The structural link between halo-like states and molecular states is explored in the case of {sup 11}Be.

  8. The Rotation-Vibration Structure of 12C

    NASA Astrophysics Data System (ADS)

    Gai, M.; Bijker, R.; Freer, M.; Kokalova, T.; Marin-Lambarri, D. J.; Wheldon, C.

    2014-12-01

    The newly measured high spin Jπ = 5- state at 22.4(2) MeV in 12C reported in this conference, fits very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D3h symmetry characterized by the sequence of states: 0+, 2+, 3- 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D3h symmetry was observed in triatomic molecules, and it is observed here for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or non observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.654 MeV in 12 C.

  9. Evidence for triangular D3h symmetry in 12C.

    PubMed

    Marín-Lámbarri, D J; Bijker, R; Freer, M; Gai, M; Kokalova, Tz; Parker, D J; Wheldon, C

    2014-07-01

    We report a measurement of a new high spin Jπ=5- state at 22.4(2) MeV in 12C which fits very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D3h symmetry characterized by the sequence 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D3h symmetry was observed in triatomic molecules, and it is observed here for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or nonobservation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.654 MeV in 12C. PMID:25032922

  10. {sup 12}C formation: A classical quest in new light

    SciTech Connect

    Tengblad, O.; Alcorta, M.; Borge, M. J. G.; Madurga, M.; Perea, A.; Cubero, M.; Fynbo, H. O. U.; Riisager, K.; Kirsebom, O.; Hyldegaard, S.; Jonson, B.; Nyman, G.; Nilsson, T.; Diget, D. G.; Fulton, B.

    2011-10-28

    In this work we have studied the break-up of {sup 12}C following the reactions {sup 10}B({sup 3}He,p{alpha}{alpha}{alpha}) and {sup 11}B({sup 3}He,d{alpha}{alpha}{alpha}). The study was performed at the 5 MV tandem in Madrid. The break-up gives us information on excited states in {sup 12}C from the famous Hoyle state up to an energy of almost 18 MeV. Using a highly segmented experimental set-up the simultaneous detection of the three alpha particles in coincidence with a proton or deuteron respectively made possible a full kinematic reconstruction of the break-up. On the basis of the energies of the 3 {alpha} particles and their angular correlations it has been possible to determine the spin and parity of states for cases in which the assignment has been doubtful. Some of these levels will also de-excite via electromagnetic emission. The comparison between the energy of proton that populate a state of {sup 12}C and the sum of the energies of the 3{alpha} emitted from the same state makes possible to determine the presence of electromagnetic disintegration ({gamma}) to lower states within {sup 12}C followed by the 3{alpha} break-up.

  11. The effect of 12C +12C rate uncertainties on the evolution and nucleosynthesis of massive stars

    NASA Astrophysics Data System (ADS)

    Bennett, M. E.; Hirschi, R.; Pignatari, M.; Diehl, S.; Fryer, C.; Herwig, F.; Hungerford, A.; Nomoto, K.; Rockefeller, G.; Timmes, F. X.; Wiescher, M.

    2012-03-01

    Over the last 40 years, the 12C +12C fusion reaction has been the subject of considerable experimental efforts to constrain uncertainties at temperatures relevant for stellar nucleosynthesis. Recent studies have indicated that the reaction rate may be higher than that currently used in stellar models. In order to investigate the effect of an enhanced carbon-burning rate on massive star structure and nucleosynthesis, new stellar evolution models and their yields are presented exploring the impact of three different 12C +12C reaction rates. Non-rotating stellar models considering five different initial masses, 15, 20, 25, 32 and 60 M⊙, at solar metallicity, were generated using the Geneva Stellar Evolution Code (GENEC) and were later post-processed with the NuGrid Multi-zone Post-Processing Network tool (MPPNP). A dynamic nuclear reaction network of ˜1100 isotopes was used to track the s-process nucleosynthesis. An enhanced 12C +12C reaction rate causes core carbon burning to be ignited more promptly and at lower temperature. This reduces the neutrino losses, which increases the core carbon-burning lifetime. An increased carbon-burning rate also increases the upper initial mass limit for which a star exhibits a convective carbon core (rather than a radiative one). Carbon-shell burning is also affected, with fewer convective-shell episodes and convection zones that tend to be larger in mass. Consequently, the chance of an overlap between the ashes of carbon-core burning and the following carbon shell convection zones is increased, which can cause a portion of the ashes of carbon-core burning to be included in the carbon shell. Therefore, during the supernova explosion, the ejecta will be enriched by s-process nuclides synthesized from the carbon-core s-process. The yields were used to estimate the weak s-process component in order to compare with the Solar system abundance distribution. The enhanced rate models were found to produce a significant proportion of Kr

  12. Centrality and system-size dependencies of temperatures of soft and hard components of pt distributions of negative pions in 4He + 12C, and 12C + 181Ta collisions at √{sN N}=3.14 GeV

    NASA Astrophysics Data System (ADS)

    Olimov, Kh. K.; Iqbal, Akhtar; Haseeb, Mahnaz Q.; Lutpullaev, S. L.; Yuldashev, B. S.

    2015-08-01

    Collision centrality as well as the system-size dependencies of the temperatures of the soft (pt=0.1 -0.5 GeV/c ) and hard (pt=0.5 -1.2 GeV/c ) components of the experimental transverse momentum distributions of the negative pions produced in 4He+12C , 12C+12C , and 12C+181Ta collisions at 4.2 A GeV/c (√{sN N}=3.14 GeV ) are analyzed. For the studied collision systems and selected collision centralities, the temperatures are extracted from fitting separately the soft and hard pt components of the negative pions by one-temperature Hagedorn and one-temperature Boltzmann functions. The extracted temperatures of both the soft and hard components of the pt distributions of π- depend on the geometry (size) and degree of overlap of the colliding nuclei in peripheral, semicentral, and central nucleus-nucleus collisions at √{sN N}=3.14 GeV . The gap (differences) between the extracted temperatures in the studied collision systems increases with increasing the degree of overlap of the colliding nuclei, i.e., with an increase in the collision centrality and the corresponding increase in the numbers of participant nucleons and binary collisions. The temperature of the soft pt component of the negative pions in 12C+12C (12C+181Ta ) collisions increases (decreases) with increasing of the collision centrality. The temperature of the hard pt component of π- in 12C+181Ta (4He+12C ) collisions increases (decreases) consistently with an increase in the collision centrality. The temperature of the soft pt component of π- decreases with an increase in the system size in semicentral and central nucleus-nucleus collisions at √{sN N}=3.14 GeV . In central collisions, the temperature of the hard pt component increases consistently with an increase in system size. The physical interpretations of the results obtained are given. The quantitative results on temperatures extracted from the pt spectra of negative pions in nucleus-nucleus collisions at 4.2 A GeV/c are compared to those

  13. Tests of Predictions of the Algebraic Cluster Model: the Triangular D 3h Symmetry of 12C

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2016-07-01

    A new theoretical approach to clustering in the frame of the Algebraic Cluster Model (ACM) has been developed. It predicts rotation-vibration structure with rotational band of an oblate equilateral triangular symmetric spinning top with a D 3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4±, 5- with a degenerate 4+ and 4- (parity doublet) states. Our measured new 2+ 2 in 12C allows the first study of rotation-vibration structure in 12C. The newly measured 5- state and 4- states fit very well the predicted ground state rotational band structure with the predicted sequence of states: 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D 3h symmetry is characteristic of triatomic molecules, but it is observed in the ground state rotational band of 12C for the first time in a nucleus. We discuss predictions of the ACM of other rotation-vibration bands in 12 C such as the (0+) Hoyle band and the (1-) bending mode with prediction of (“missing 3- and 4-”) states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or non observation) of the predicted (“missing”) states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.6542 MeV in 12C. We discuss proposed research programs at the Darmstadt S-DALINAC and at the newly constructed ELI-NP facility near Bucharest to test the predictions of the ACM in isotopes of carbon.

  14. Emission of charged particles from excited compound nucleus

    SciTech Connect

    Kalandarov, Sh. A.; Adamian, G. G.; Antonenko, N. V.

    2010-11-24

    The formation and decay of excited compound nucleus are studied within the dinuclear system model[1]. The cross sections of complex fragment emission are calculated and compared with experimental data for the reactions {sup 3}He+{sup 108}Ag, {sup 78,82}Kr+{sup 12}C. Angular momentum dependence of cluster emission in {sup 78}Kr+{sup 12}C and {sup 40}Ca+{sup 78}Kr reactions is demonstrated.

  15. 12C(p,p‧) scattering measurement at forward angles

    NASA Astrophysics Data System (ADS)

    Tamii, A.; Adachi, T.; Fujita, K.; Hatanaka, K.; Hashimoto, H.; Itoh, M.; Matsubara, H.; Nakanishi, K.; Sakemi, Y.; Shimbara, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Fujita, Y.; Sakaguchi, H.; Zenihiro, J.; Kawabata, T.; Sasamoto, Y.; Dozono, M.; Carter, J.; Fujita, H.; Rubio, B.; Perez, A.

    Experimental method of measuring inelastic proton scattering with high-resolution at forward angles including zero degrees has been developed. An energy resolution of 20 keV and a scattering angle resolution of 0.5 degrees have been achieved as well as low background condition and a reliable background subtraction method. The experimental technique was applied to the 12C(p,p‧) reaction for studying the property of the second 0+ state at 7.7 MeV and a broad bump around Ex~10 MeV, where the presence of a 2+ state was reported from the 12C(α,α‧) measurement. Preliminary spectra and angular distributions are shown.

  16. Observation of. lambda. -hypernuclei in the reaction /sup 12/C(. pi. /sup +/,K/sup +/)/sub. lambda. //sup 12/C

    SciTech Connect

    Milner, E.C.

    1985-12-01

    The observation of ..lambda..-hypernuclear levels in /sub ..lambda..//sup 12/C by associated production through the (..pi../sup +/,K/sup +/) reaction is reported. Spectrometers used in the measurements are discussed. The /sub ..lambda..//sup 12/C excitation energy spectra were recorded at laboratory scattering angles of 5.6/sup 0/, 10.3/sup 0/, and 15.2/sup 0/. The spectra show two major peaks - one attributed to the ground state, and one about 11 MeV higher in excitation. The peak near 11 MeV excitation energy is believed to be almost entirely composed of a multiplet of three J/sup ..pi../ = 2/sup +/ states. Relativistic DWBA calculations imply support for the expectation that higher spin states are preferentially populated in the (..pi../sup +/,K/sup +/) reaction, compared to the (K/sup -/,..pi../sup -/) reaction in which lower spin states are excited. 29 refs., 40 figs.

  17. AGB fluorine nucleosynthesis studied by means of Trojan-horse method: the case of {sup 15}N(p,{alpha}){sup 12}C

    SciTech Connect

    Pizzone, R. G.; Spitaleri, C.; La Cognata, M.; Cherubini, S.; Crucilla, V.; Gulino, M.; Lamia, L.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, S.; Tumino, A.; Tribble, R.; Trache, L.; Fu, C.; Goldberg, V.; Mukhamedzhanov, A.; Tabacaru, G.

    2008-05-12

    The low-energy bare-nucleus cross section for {sup 15}N(p,{alpha}){sup 12}C is extracted by means of the Trojan-horse Method applied to the {sup 2}H({sup 15}N,{alpha}){sup 12}C)n reaction at E{sub beam} = 60 MeV. The astrophysical S-factor is deduced and compared to the direct data in the same energy region. A fair agreement with direct data down to 80 keV is found if energy resolution effects are taken into account.

  18. Electromagnetic Response of 12C: A First-Principles Calculation

    NASA Astrophysics Data System (ADS)

    Lovato, A.; Gandolfi, S.; Carlson, J.; Pieper, Steven C.; Schiavilla, R.

    2016-08-01

    The longitudinal and transverse electromagnetic response functions of 12C are computed in a "first-principles" Green's function Monte Carlo calculation, based on realistic two- and three-nucleon interactions and associated one- and two-body currents. We find excellent agreement between theory and experiment and, in particular, no evidence for the quenching of the measured versus calculated longitudinal response. This is further corroborated by a reanalysis of the Coulomb sum rule, in which the contributions from the low-lying Jπ=2+, 02+ (Hoyle), and 4+ states in 12 are accounted for explicitly in evaluating the total inelastic strength.

  19. Nuclear transparency from quasielastic 12C(e,e'p)

    SciTech Connect

    D. Rohe; O. Benhar; C.S. Armstrong; R. Asaturyan; O.K. Baker; S. Bueltmann; C. Carasco; D. Day; R. Ent; H.C. Fenker; K. Garrow; A. Gasparian; P. Gueye; M. Hauger; A. Honegger; J. Jourdan; C.E. Keppel; G. Kubon; R. Lindgren; A. Lung; D.J. Mack; J.H. Mitchell; H. Mkrtchyan; D. Mocelj; K. Normand; T. Petitjean; O. Rondon; E. Segbefia; I. Sick; S. Stepanyan; L. Tang; F. Tiefenbacher; W.F. Vulcan; G. Warren; S.A. Wood; L. Yuan; M. Zeier; H. Zhu; B. Zihlmann

    2005-11-01

    We studied the reaction 12C(e,e'p) in quasielastic kinematics at momentum transfers between 0.6 and 1.8 (GeV/c){sup 2} covering the single-particle region. From this the nuclear transparency factors are extracted using two methods. The results are compared to theoretical predictions obtained using a generalization of Glauber theory described in this paper. Furthermore, the momentum distribution in the region of the 1s-state up to momenta of 300 MeV/c is obtained from the data and compared to the Correlated Basis Function theory and the Independent-Particle Shell model.

  20. 2{sup +} excitation of the {sup 12}C Hoyle state

    SciTech Connect

    Freer, M.; Fujita, H.; Carter, J.; Usman, I.; Buthelezi, Z.; Foertsch, S. V.; Neveling, R.; Perez, S. M.; Smit, F. D.; Fearick, R. W.; Papka, P.; Swartz, J. A.

    2009-10-15

    A high-energy-resolution magnetic spectrometer has been used to measure the {sup 12}C excitation energy spectrum to search for the 2{sup +} excitation of the 7.65 MeV, 0{sup +} Hoyle state. By measuring in the diffractive minimum of the angular distribution for the broad 0{sup +} background, evidence is found for a possible 2{sup +} state at 9.6(1) MeV with a width of 600(100) keV. The implications for the {sup 8}Be+{sup 4}He reaction rate in stellar environments are discussed.

  1. Symplectic structure and monopole strength in {sup 12}C

    SciTech Connect

    Yoshida, T.; Itagaki, N.; Kato, K.

    2011-02-15

    The relation between the monopole transition strength and existence of cluster structure in the excited states is discussed based on an algebraic cluster model. The structure of {sup 12}C is studied with a 3{alpha} model, and the wave function for the relative motions between {alpha} clusters are described by the symplectic algebra Sp(2, R){sub z}, which corresponds to the linear combinations of SU(3) states with different multiplicities. Introducing Sp(2,R){sub z} algebra works well for reducing the number of the basis states, and it is also shown that states connected by the strong monopole transition are classified by a quantum number {Lambda} of the Sp(2,R){sub z} algebra.

  2. Study of /sup 12/C interactions at HISS

    SciTech Connect

    Crawford, H.J.

    1982-12-01

    Single-particle inclusive measurements in high-energy nuclear physics have provided the foundation for a number of models of interacting nuclear fluids. Such measurements yield information on the endpoints of the evolution of highly excited nuclear systems. However, they suffer from the fact that observed particles can be formed in a large number of very different evolutionary paths. To learn more about how interactions proceed we have performed a series of experiments in which all fast nuclear fragments are analyzed for each individual interaction. These experiments were performed at the LBL Bevalac HISS (Heavy Ion Spectrometer System) facility where we studied the interaction of 1 GeV/nuc 12C nuclei with targets of C, CH/sub 2/, Cu, and U. In this paper we describe HISS and present some preliminary results of the experiment.

  3. Low-energy neutron direct capture by 12C in a dispersive optical potential

    NASA Astrophysics Data System (ADS)

    Kitazawa, H.; Go, K.; Igashira, M.

    1998-01-01

    A dispersive optical potential for the interaction between low-energy neutrons and 12C nuclei is derived from a dispersion relation based on the Feshbach generalized optical model. The potential reproduces completely neutron total cross sections below 1.0 MeV and substantially reproduces the energy of the 3090 keV(1/2+) level in 13C which is of nearly pure 2s1/2 single-particle character. It is found that direct-capture model calculations with this potential explain quite successfully the observed off-resonance capture transitions to the ground (1/2-), 3090 keV(1/2+), 3685 keV(3/2-), and 3854 keV(5/2+) levels in 13C at neutron energies of 20-600 keV. Special emphasis is laid on the fact that in these model analyses, account should be taken of the spatial nonlocality of the neutron-nucleus interaction potential, in particular for negative energies.

  4. Low-energy neutron direct capture by {sup 12}C in a dispersive optical potential

    SciTech Connect

    Kitazawa, H.; Go, K.; Igashira, M.

    1998-01-01

    A dispersive optical potential for the interaction between low-energy neutrons and {sup 12}C nuclei is derived from a dispersion relation based on the Feshbach generalized optical model. The potential reproduces completely neutron total cross sections below 1.0 MeV and substantially reproduces the energy of the 3090keV(1/2{sup +}) level in {sup 13}C which is of nearly pure 2s{sub 1/2} single-particle character. It is found that direct-capture model calculations with this potential explain quite successfully the observed off-resonance capture transitions to the ground (1/2{sup {minus}}), 3090keV(1/2{sup +}), 3685keV(3/2{sup {minus}}), and 3854keV(5/2{sup +}) levels in {sup 13}C at neutron energies of 20{endash}600 keV. Special emphasis is laid on the fact that in these model analyses, account should be taken of the spatial nonlocality of the neutron-nucleus interaction potential, in particular for negative energies. {copyright} {ital 1998} {ital The American Physical Society}

  5. Energies of molecular structures in 12C,16O,20Ne,24Mg, and 32S

    NASA Astrophysics Data System (ADS)

    Royer, G.; Ramasamy, G.; Eudes, P.

    2015-11-01

    The energies of the 12C,16O,20Ne,24Mg, and 32S 4 n nuclei have been determined within a generalized liquid drop model and assuming different planar and three-dimensional shapes of the α molecules: linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octagon, and cube. The potential barriers governing the entrance and decay channels via α absorption or emission as well as more symmetric binary and ternary reactions have been compared. The rms radii of the linear chains differ from the experimental rms radii of the ground states. The binding energies of the three-dimensional shapes at the contact point are higher than the ones of the planar configurations. The α particle plus A-4 daughter configuration leads always to the lowest potential barrier. The binding energy can be reproduced within the sum of the binding energy of n α particles plus the number of bonds multiplied by 2.4 MeV or by the sum of the binding energies of one α particle and the daughter nucleus plus the Coulomb energy and the proximity energy.

  6. {sup 35}Cl+{sup 12}C asymmetrical fission excitation functions

    SciTech Connect

    Beck, C.; Mahboub, D.; Nouicer, R.; Matsuse, T.; Djerroud, B.; Freeman, R.M.; Haas, F.; Hachem, A.; Morsad, A.; Youlal, M.; Dayras, R.; Wieleczko, J.P.; Berthoumieux, E.; Legrain, R.; Pollacco, E.

    1996-07-01

    The fully energy-damped yields from the {sup 35}Cl+{sup 12}C reaction have been systematically investigated using particle-particle coincidence techniques at a {sup 35}Cl bombarding energy of {approximately}8 MeV/nucleon. The fragment-fragment correlation data show that the majority of events arises from a binary-decay process with rather large numbers of secondary light-charged particles emitted from the two excited exit fragments. No evidence is observed for ternary break-up events. The binary-process results of the present measurement, along with those of earlier, inclusive experimental data obtained at several lower bombarding energies are compared with predictions of two different kinds of statistical model calculations. These calculations are performed using the transition-state formalism and the extended Hauser-Feshbach method and are based on the available phase space at the saddle point and scission point of the compound nucleus, respectively. The methods give comparable predictions and are both in good agreement with the experimental results thus confirming the fusion-fission origin of the fully damped yields. The similarity of the predictions for the two models supports the claim that the scission point configuration is very close to that of the saddle point for the light {sup 47}V compound system. The results also give further support for the specific mass-asymmetry-dependent fission barriers needed in the transition-state calculation. {copyright} {ital 1996 The American Physical Society.}

  7. High energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Wosiek, B.

    1986-01-01

    Experimental results on high energy nucleus-nucleus interactions are presented. The data are discussed within the framework of standard super-position models and from the point-of-view of the possible formation of new states of matter in heavy ion collisions.

  8. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  9. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  10. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  11. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  12. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  13. Nucleus-nucleus scattering at high energies

    NASA Technical Reports Server (NTRS)

    Franco, V.; Varma, G. K.

    1977-01-01

    Nucleus-nucleus scattering is treated in the Glauber approximation. The usual optical limit result, generally thought to improve as the number of nucleons in the colliding nuclei increases, is found to be the first term of a series which diverges for large nuclei. Corrections to the optical limit are obtained which provide a means of performing realistic calculations for collisions involving light nuclei. Total cross section predictions agree well with recent measurements.

  14. One- and two-step mechanisms of the 9Be( 12C, 11B) 10B reaction at Elab( 12C)=65 MeV and the energy dependence of 11,10B+ 10B interactions

    NASA Astrophysics Data System (ADS)

    Rudchik, A. T.; Momotyuk, O. A.; Budzanowski, A.; Chernievsky, V. K.; Koshchy, E. I.; Mokhnach, A. V.; Ziman, V. A.; Kliczewski, S.; Siudak, R.; Skwirczyńska, I.; Szczurek, A.; Makowska-Rzeszutko, M.; G l̵owacka, L.; Turkiewicz, J.

    2000-09-01

    Angular distributions of the 9Be( 12C, 11B) 10B reaction were measured at the energy of Elab( 12C)=65 MeV for transitions to the ground and 0.72 MeV (1 +), 1.74 MeV (0 +, T=1), 3.59 MeV (2 +) excited states of the 10B nucleus and 2.12 MeV (1/2 -)+2.15 MeV (1 +) excited states of 11B and 10B nuclei, respectively. Data were analyzed within the coupled reaction channel (CRC) model including one- and two-step transfer mechanisms. The elastic and inelastic scattering and p-, d-, (d + n)-, (n + p)-, ( 3He + p)- and ( 3He + d)-transfer mechanisms were included in the coupled channel scheme. It was found that two-step processes are important for all transitions. Data of 10B+ 10B elastic scattering from the literature were included in the analysis of the energy dependence of optical model parameters for 10B+ 10B and 10B+ 11B interactions. A good description of all sets of experimental data was achieved.

  15. Effect of repulsive and attractive three-body forces on nucleus-nucleus elastic scattering

    SciTech Connect

    Furumoto, T.; Sakuragi, Y.; Yamamoto, Y.

    2009-10-15

    The effect of the three-body force (TBF) is studied in nucleus-nucleus elastic scattering on the basis of Brueckner theory for nucleon-nucleon (NN) effective interaction (complex G matrix) in the nuclear matter. A new G matrix called CEG07 proposed recently by the present authors includes the TBF effect and reproduces a realistic saturation curve in the nuclear matter, and it is shown to well reproduce proton-nucleus elastic scattering. The microscopic optical potential for the nucleus-nucleus system is obtained by folding the G matrix with nucleon density distributions in colliding nuclei. We first analyze in detail the {sup 16}O+{sup 16}O elastic scattering at E/A=70 MeV. The observed cross sections are nicely reproduced up to the most backward scattering angles only when the TBF effect is included. The use of the frozen-density approximation (FDA) is essentially important to properly estimate the effect of the TBF in nucleus-nucleus scattering. Other prescriptions for defining the local density have also been tested, but only the FDA prescription gives a proper description of the experimental cross sections as well as the effect of the TBF. The effects of the three-body attraction and the {omega}-rearrangement term are also analyzed. The CEG07 interaction is compared with CDM3Y6, which is a reliable and successful effective density-dependent NN interaction used in the double-folding model. The CEG07 G matrix is also tested in the elastic scattering of {sup 16}O by the {sup 12}C, {sup 28}Si, and {sup 40}Ca targets at E/A=93.9 MeV, and in the elastic scattering of {sup 12}C by the {sup 12}C target at E/A=135 MeV with great success. The decisive effect of the TBF is clearly seen also in those systems. Finally, we have tested CEG07a, CEG07b, and CEG07c for the {sup 16}O+{sup 16}O system at various energies.

  16. Velocity spectra and angular distributions of evaporation residues from sup 32 S + sup 12 C at 145 MeV

    SciTech Connect

    Arena, N.; Cavallaro, S.; Femino', S.; Figuera, P.; Pirrone, S.; Porto, F.; Sambataro, S. )

    1991-11-01

    Velocity spectra and angular and mass distributions for the evaporation residues of the {sup 32}S+{sup 12}C system at {ital E}{sup 32}S=145 MeV in the angular range 3{degree}{le}{var theta}{sub {ital L}}{le}12{degree} have been measured. In order to separate compound nucleus evaporation residues from other heavy reaction products, a kinematic analysis based on simple statistical assumptions relative to the velocity spectra was performed. The structures in the mass distribution are compared with the LILITA code predictions. The fusion excitation function of the existing results is compared with theoretical models. The total reaction cross section has been extracted by means of the modified sum of differences method.

  17. Reconstruction of ^16O(,)^12C Events in the HIγS Optical Readout Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Stave, S.; Ahmed, M. W.; Clinton, E. R.; Howell, C. R.; Seo, P.-N.; Weller, H. R.; Gai, M.; Young, A. H.; Bromberger, B.; Dangendorf, V.; Tittelmeier, K.

    2008-10-01

    A new optical readout time projection chamber (O-TPC) is in use at the High Intensity γ-ray Source (HIγS) located at the Free Electron Laser Laboratory on the Duke University campus. One application of the HIγS O-TPC is the study of the inverse of the ^12C(,)^16O reaction which is important for stellar evolution theory. In the O-TPC, incoming γ-rays interact with an ^16O nucleus producing an α and a ^12C which then leave trails of ionization electrons along their path. The O-TPC then provides several signals each of which must be interpreted simultaneously to determine the different particle types, their energies and their directions. Part of the challenge of operating the O-TPC is integrating the fast signals from the photomultiplier tubes and drift chamber with the slow signals from the CCD camera which images the tracks. Automated routines have been developed to take all of the available track information and provide a reliable determination of the interaction cross section. Examples of the method and preliminary results will be presented.

  18. Terahertz Spectroscopy and Global Analysis of the Bending Vibrations of ^{12}C_2H_2 and ^{12}C_2D_2

    NASA Astrophysics Data System (ADS)

    Yu, Shanshan; Drouin, Brian J.; Pearson, John C.; Pickett, Herbert M.; Lattanzi, Valerio; Walters, Adam

    2009-06-01

    Symmetric molecules have no permanent dipole moment and are undetectable by rotational spectroscopy. Their interstellar observations have previously been limited to mid-infrared vibration-rotation spectroscopy. Although relatively weak, vibrational difference bands provide a means for detection of non polar molecules by terahertz techniques with microwave precision. Herschel, SOFIA, and ALMA have the potential to identify a number of difference bands of light symmetric species, e.g., C_2H_2, CH_4 and C_3. This paper reports the results of the laboratory study on ^{12}C_2H_2 and ^{12}C_2D_2. The symmetric isotopomers of acetylene have two bending modes, the trans bending ν_4 (^1{π}_g), and the cis bending ν_5 (^1{π}_u). For ^{12}C_2H_2, the two bending modes occur at 612 and 729 cm^{-1}, respectively. For ^{12}C_2D_2, the two bending modes occur at 511 and 538 cm^{-1}. The ν_5-ν_4 difference bands are allowed and occur in the microwave, terahertz, and far-infrared wavelengths, with band origins at 117 cm^{-1} (3500 GHz) for ^{12}C_2H_2 and 27 cm^{-1} (900 GHz) for ^{12}C_2D_2. Two hundred and fifty-one ^{12}C_2D_2 transitions, which are from ν_5-ν_4, (ν_5+ν_4)-2ν_4 and 2ν_5-(ν_5+ν_4) bands, have been measured in the 0.2-1.6 THz region, and 202 of them were observed for the first time. The precision of these measurements is estimated to be from 50 kHz to 100 kHz. A multistate analysis was carried out for the bending vibrational modes ν_4 and ν_5 of ^{12}C_2D_2, which includes the lines observed in this work and prior microwave, far-infrared and infrared data on the pure bending levels. Significantly improved molecular parameters were obtained for ^{12}C_2D_2 by adding the new measurements to the old data set which had only 10 lines with microwave measurement precision. The experiments on ^{12}C_2H_2 are in progress and ten P branch lines have been observed. We will present the ^{12}C_2H_2 results to date.

  19. Measurement of the di-electron mass spectrum in 12C+12C collisions at 2 AGeV by HADES

    SciTech Connect

    Sudol, Malgorzata

    2006-07-11

    The High Acceptance DiElectron Spectrometer (HADES) has been constructed at the SIS accelerator (GSI, Darmstadt) to investigate electron-positron pairs produced in proton, pion and heavy-ion induced reactions. The physics programme of HADES is focused on in-medium properties of light vector mesons. In this contribution the HADES experiment is outlined and first results obtained for 12C + 12C collisions at 2 AGeV are presented.

  20. Measurement of the complete fusion cross section of /sup 12/C+/sup 159/Tb, /sup 12/C+/sup 165/Ho

    SciTech Connect

    Wang Sufang; Cai Wei; Zheng Jiwen

    1989-07-01

    Complete fusion cross sections have been measured for /sup 12/C+/sup 159/Tb and /sup 12/C+/sup 165/Ho reactions by measuring /ital K/--/ital X/ rays of evaporation residues with a Si (Li) spectrometer. The half-lives of evaporation residues and their yield distributions as a function of incident energy have also been obtained. The experimental values for complete fusion cross sections were compared with the theoretical ones.

  1. Coupling and higher-order effects in the {sup 12}C(d,p){sup 13}C and {sup 13}C(p,d){sup 12}C reactions

    SciTech Connect

    Delaunay, F.; Nunes, F.M.; Lynch, W.G.; Tsang, M.B.

    2005-07-01

    Coupled-channel calculations are performed for the {sup 12}C(d,p){sup 13}C and {sup 13}C(p,d){sup 12}C reactions between 7 and 60 MeV to study the effect of inelastic couplings in transfer reactions. The effect of treating transfer beyond Born approximation is also addressed. The coupling to the {sup 12}C 2{sup +} state is found to change the peak cross section by up to 15%. Effects beyond Born approximation lead to a significant renormalization of the cross sections, between 5% and 10% for deuteron energies above 10 MeV and larger than 10% for lower energies. We also performed calculations including the remnant term in the transfer operator, which has a small impact on the {sup 12}C(d,p){sup 13}C(g.s.) and {sup 13}C(p,d){sup 12}C(g.s.) reactions (where g.s. indicates ground state). Above 30-MeV deuteron energy, the effect of the remnant term is larger than 10% for the {sup 12}C(d,p){sup 13}C(1/2{sup +}, 3.09 MeV) reaction and is found to increase with decreasing neutron separation energy for the 3.09-MeV state of {sup 13}C. This is of importance for transfer reactions with weakly bound nuclei.

  2. Investigation of Proton-Proton Short-Range Correlations via the 12C(e,eï ½Rpp) Reaction

    SciTech Connect

    Sheyor, Ran

    2007-12-01

    In this work we present a simultaneous measurement of the 12C(e,e2p) and 12C(e,e2pp) reactions. This measurement was done as part of the E01-015 experiment at Hall A of Jefferson Lab, at Q2 = 2 (GeV/c) 2 , B x = 1.2, for an (e,e2p) missing-momentum range from 300 to 600 MeV/c. At these kinematics conditions, with a missing-momentum greater than the Fermi momentum of nucleons in a nucleus and far from the D excitation, nucleon-nucleon Short-Range Correlations (SRCs) are predicted to dominate the reaction. For 9.5 ± 2% of the 12C(e,e2p) events, a recoiling partner proton was observed in the opposite direction to the 12C(e,e2p) missing momentum vector with roughly equal momentum. This observation is an experimental signature for proton-proton short-range correlations (pp-SRC) in nuclei. Even though the probability of pp-SRCs in nuclei is small, they are important since they can teach us about the strong interaction at short distances. Moreover, as a manifestation of asymmetric

  3. Kaon-Nucleus Interaction Studied through the In-Flight (K-,N) Reaction

    NASA Astrophysics Data System (ADS)

    Kishimoto, T.; Hayakawa, T.; Ajimura, S.; Khanam, F.; Itabashi, T.; Matsuoka, K.; Minami, S.; Mitoma, Y.; Sakaguchi, A.; Shimizu, Y.; Terai, K.; Chrien, R. E.; Pile, P.; Noumi, H.; Sekimoto, M.; Takahashi, H.; Fukuda, T.; Imoto, W.; Mizoi, Y.

    2007-08-01

    We studied the bar{K}-nucleus interaction by the 12C(K-,N) reaction. Missing mass spectra were derived from the momenta of both neutrons and protons from the reaction. An appreciable strength was observed below the bar{K}-nucleus threshold, which indicates that the bar{K}-nuclear potential is strongly attractive. The missing mass spectra are compared with the results of theoretical calculations. It is found that a potential depth of approximately -190 MeV best reproduces the spectrum of the 12C(K-,n) reaction and approximately -160 MeV best reproduces that of the 12C(K-,p) reaction. Our data show that the bar{K}-nucleus potential is sufficiently deep to realize kaon condensation in the core of neutron stars.

  4. bar{K}-Nucleus Interaction Probed by the In-Flight (K^-,N) Reactions

    NASA Astrophysics Data System (ADS)

    Kishimoto, T.; Hayakawa, T.; Ajimura, S.; Khanam, F.; Itabashi, T.; Matsuoka, K.; Minami, S.; Mitoma, Y.; Sakaguchi, A.; Shimizu, Y.; Terai, K.; Chrien, R. E.; Pile, P.; Noumi, H.; Sekimoto, M.; Takahashi, H.; Fukuda, T.; Imoto, W.; Mizoi, Y.

    We would like to point out that the (K^-,N) reactions are particularly useful for the study of the bar{K}-nucleus interaction. We have measured the missing mass spectra derived from the momenta of both neutrons and protons from the ^{12}{C}(K^-,N) reactions. It was found that an appreciable amount of strength were below the bar{K}-nucleus threshold which indicates that the bar{K}-nuclear potential is strongly attractive. The missing mass spectra are compared with theoretical calculations. It is found that a potential depth of around -190 MeV reproduces well the spectrum of the ^{12}C(K^-,n) reaction and a less deep potential of around -160 MeV reproduces well that of the ^{12}C(K^-,p) reaction. Our data show that the bar{K}-nucleus potential is very deep to realize kaon condensation in the core of neutron stars.

  5. Alpha particle condensation in {sup 12}C and nuclear rainbow scattering

    SciTech Connect

    Ohkubo, S.; Hirabayashi, Y.

    2008-05-12

    It is shown that the large radius of the Hoyle state of {sup 12}C with a dilute density distribution in an {alpha} particle condensate can be clearly seen in the shift of the rainbow angle (therefore the Airy minimum) to a larger angle in {alpha}+{sup 12}C rainbow scattering at the high energy region and prerainbow oscillations in {sup 3}He+{sup 12}C scattering at the lower energy region.

  6. Molecular structure in /sup 12/C + /sup 12/C, orbiting in /sup 12/C + /sup 28/Si, and first studies of the /sup 60/Ni + /sup 60/Ni interaction

    SciTech Connect

    Erb, K.A.; Ford, J.L.C. Jr.; Novotny, R.; Shapira, D.

    1981-01-01

    Some physical implications of a recently proposed classification scheme for the /sup 12/C + /sup 12/C Coulomb barrier resonances for which the requisite very large body of experimental data is already available are discussed. New data are presented suggesting that the back angle resonance-like structure previously observed in quasi-elastic /sup 28/Si + /sup 12/C reactions reflects the existence of a fully developed, rotating di-nuclear system that governs back-angle yields in many additional exit channels. Also some very recent data are briefly discussed for /sup 60/Ni + /sup 60/Ni scattering in a first look at a previously unstudied region of the periodic table. (WHK)

  7. Counting the number of correlated pairs in a nucleus

    SciTech Connect

    Vanhalst, Maarten; Cosyn, Wim; Ryckebusch, Jan

    2011-09-15

    We suggest that the number of correlated nucleon pairs in an arbitrary nucleus can be estimated by counting the number of proton-neutron, proton-proton, and neutron-neutron pairs residing in a relative S state. We present numerical calculations of those amounts for the nuclei {sup 4}He, {sup 9}Be, {sup 12}C, {sup 27}Al, {sup 40}Ca, {sup 48}Ca, {sup 56}Fe, {sup 63}Cu, {sup 108}Ag, and {sup 197}Au. The results are used to predict the values of the ratios of the per-nucleon electron-nucleus inelastic scattering cross section to the deuteron in the kinematic regime where correlations dominate.

  8. (. pi. sup +- ,. pi. sup +- prime N) reactions on sup 12 C and sup 208 Pb near the giant resonance region

    SciTech Connect

    Yoo, Sung Hoon.

    1990-05-01

    Angular distributions for the {sup 12}C({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p) and {sup 208}Pb({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p or n) reactions near the giant resonance region have been measured at T{sub {pi}} = 180 MeV, and found different between {pi}{sup +} and {pi}{sup {minus}} data. This observation is interpreted as evidence for different excitation mechanisms dominating the {pi}{sup {minus}}-nucleus and {pi}{sup +}-nucleus interactions in the giant resonance region of these targets. A comparison with the single-nucleon knock-out distorted-wave impulse approximation calculations shows, even though these calculations underestimate ({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} N) data for both targets, the dominance of direct process for ({pi}{sup +}, {pi}{sup {plus}}{prime} p) or ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} n) in contrast to ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) or ({pi}{sup +}, {pi}{sup +}{prime} n). In the ({pi}{sup +}, {pi}{sup +}{prime} p) reaction proton-proton hole states are excited directly and appear to have a large probability for direct decay with escape width, whereas in ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) the preferentially excited neutron-neutron hole doorway states couple to resonance states and decay with spreading width. This interpretation led us to suggest that the ratio of cross-sections for inelastic scattering to the giant resonance region should be written in terms of an incoherent sum of cross-sections to neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states contribute incoherently because the different decay processes do not populate the same final states of the residual nucleus.

  9. Neutrino magnetic moment effects in neutrino nucleus reactions

    SciTech Connect

    Singh, S.K.; Athar, M.S.

    1995-10-01

    Some low energy neutrino nucleus reactions induced by neutrinos (antineutrinos) having a magnetic moment of the order of 10{sup {minus}9}{minus}10{sup {minus}10} Bohr magneton are studied. It is found that in the case of {sup 4}He, {sup 12}C, and {sup 16}O, the detection of very low energy scalar and isoscalar elastic and inelastic reactions induced by the isoscalar vector currents can provide a better limit on the neutrino magnetic moment.

  10. Exotic atoms, K-nucleus scattering and hypernuclei

    SciTech Connect

    Barnes, P. D.

    1981-01-01

    Recent progress in exotic atom physics, kaon-nucleus scattering, and hypernuclear physics is reviewed. Specific problems discussed include searches for muon-nucleon interactions beyond QED, a comparison of data and recent calculation of K/sup + -/ + /sup 12/C elastic and inelastic scattering, as well as recent studies of ..sigma.. and ..lambda.. hypernuclei including new data on the level structure of /sup 13/C/..lambda...

  11. Holmium target fragmentation induced by intermediate energy /sup 12/C and /sup 16/O ions

    SciTech Connect

    Kraus, R.H. Jr.

    1986-01-01

    Target fragment (40 < A < 180) production cross sections were measured using off-line gamma-ray spectroscopy for the interaction of 208 MeV /sup 12/C, 272 MeV /sup 16/O, 442 MeV/sup 12/C, 1020 MeV /sup 12/C, and 1635 MeV /sup 16/O with /sup 165/Ho. Target fragment isobaric yields were deduced from these measurements. Trans-target nuclides were identified for all reaction systems. Nuclides up to 4 Z-units above the target were identified for 208 MeV /sup 12/C and 272 MeV /sup 16/O induced reactions, to 3 Z-units above the target for 442 MeV /sup 12/C and 1020 MeC /sup 12/C induced reactions, and to 2 Z-units above the target for 1635 MeV /sup 16/O induced reactions. Fission was observed to decrease between 17 MeV/A and 37 MeV/A from 13% of the reaction cross section to 4% for /sup 12/C induced reactions. No fission contribution was observed for 1020 MeV /sup 12/C and 1635 MeV /sup 16/O induced interactions.

  12. Dilute Nuclear States: {sup 12}C, {sup 10}Be and {sup 14}C

    SciTech Connect

    Freer, M.

    2008-11-11

    The experimental evidence for dilute {alpha}-particle states in {sup 12}C, {sup 10}Be and {sup 14}C is discussed. The question of the location of the 2{sup +} excitation of the 7.65 MeV {sup 12}C state remains unresolved, as does the existence of possible analogue states in {sup 14}C.

  13. Simulations of ^12C Break Up In A Twin Ionization Chamber

    NASA Astrophysics Data System (ADS)

    Segal, C. B.; Patel, N. R.; Greife, U.; Rehm, K. E.; Deibel, C. M.; Greene, J.; Henderson, D.; Jiang, C. L.; Kay, B. P.; Lee, H. Y.; Pardo, R.; Notani, M.; Marley, S. T.; Tang, X. D.

    2008-10-01

    In stellar explosions the triple α decay process is key to forming the life-giving ^12C . This experiment is to further investigate the energy region in ^12C around 10 MeV where a theoretically predicted 2^+ state has yet to be observed. The motivation for studying this is to better understand the ^12C nucleosynthesis process that occurs in red giant stars where the short lived ^8Be interacts with alphas at extreme temperature and pressure scenarios which then in turn creates ^12C. We study the particle-unbound states by implanting ^12B into a twin Frisch grid ionization chamber and following the decay into ^12C and subsequently into three α particles. The response of this ionization chamber to the detection of multiple α particles was studied using various simulation programs. Results of these simulations and limits for the predicted 2^+ state will be presented.

  14. Allele-specific inhibitors inactivate mutant KRAS G12C by a trapping mechanism

    PubMed Central

    Lito, Piro; Solomon, Martha; Li, Lian-Sheng; Hansen, Rasmus; Rosen, Neal

    2016-01-01

    It is thought that KRAS oncoproteins are constitutively active because their guanosine triphosphatase (GTPase) activity is disabled. Consequently, drugs targeting the inactive or guanosine 5′-diphosphate–bound conformation are not expected to be effective. We describe a mechanism that enables such drugs to inhibit KRASG12C signaling and cancer cell growth. Inhibition requires intact GTPase activity and occurs because drug-bound KRASG12C is insusceptible to nucleotide exchange factors and thus trapped in its inactive state. Indeed, mutants completely lacking GTPase activity and those promoting exchange reduced the potency of the drug. Suppressing nucleotide exchange activity downstream of various tyrosine kinases enhanced KRASG12C inhibition, whereas its potentiation had the opposite effect. These findings reveal that KRASG12C undergoes nucleotide cycling in cancer cells and provide a basis for developing effective therapies to treat KRASG12C-driven cancers. PMID:26841430

  15. Allele-specific inhibitors inactivate mutant KRAS G12C by a trapping mechanism.

    PubMed

    Lito, Piro; Solomon, Martha; Li, Lian-Sheng; Hansen, Rasmus; Rosen, Neal

    2016-02-01

    It is thought that KRAS oncoproteins are constitutively active because their guanosine triphosphatase (GTPase) activity is disabled. Consequently, drugs targeting the inactive or guanosine 5'-diphosphate-bound conformation are not expected to be effective. We describe a mechanism that enables such drugs to inhibit KRAS(G12C) signaling and cancer cell growth. Inhibition requires intact GTPase activity and occurs because drug-bound KRAS(G12C) is insusceptible to nucleotide exchange factors and thus trapped in its inactive state. Indeed, mutants completely lacking GTPase activity and those promoting exchange reduced the potency of the drug. Suppressing nucleotide exchange activity downstream of various tyrosine kinases enhanced KRAS(G12C) inhibition, whereas its potentiation had the opposite effect. These findings reveal that KRAS(G12C) undergoes nucleotide cycling in cancer cells and provide a basis for developing effective therapies to treat KRAS(G12C)-driven cancers. PMID:26841430

  16. Fusion cross section of 12C+13C at sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Zhang, N. T.; Tang, X. D.; Chen, H.; Chesneanu, D.; Straticiuc, M.; Trache, L.; Burducea, I.; Li, K. A.; Li, Y. J.; Ghita, D. G.; Margineanu, R.; Pantelica, A.; Gomoiu, C.

    2016-02-01

    In the recent work at Notre Dame, correlations between three carbon isotope fusion systems have been studied and it is found that the fusion cross sections of 12C+13Cand 13C+13C provide an upper limit on the fusion cross section of the astrophysically important 12C+12C reaction.The aim of this work is to continue such research by measuring the fusion cross section of the 12C+13C reaction to lower energies. In this experiment, the off-line activity measurement was performed in the ultra-low background laboratory 12C+13C and the fusion cross section for has been determined in the energy range of Ec.m. =2.5-6.8 MeV. Comparison between this work and several models is also presented.

  17. Study of two- and multi-particle correlations in 12C+24Mg and 12C+208Pb reactions at E=35 AMeV

    NASA Astrophysics Data System (ADS)

    Quattrocchi, L.; Acosta, L.; Amorini, F.; Anzalone, A.; Auditore, L.; Berceanu, I.; Cardella, G.; Chbihi, A.; De Filippo, E.; Dell'Aquila, D.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martel, I.; Minniti, T.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Veselsky, M.; Vigilante, M.

    2016-05-01

    Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30°) of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z˜3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

  18. EFFECTS OF NUCLEAR INDUCED BREAKUP ON THE FUSION OF 6Li+12C AND 6He+12C SYSTEMS AROUND BARRIER ENERGIES

    NASA Astrophysics Data System (ADS)

    Duhan, Sukhvinder S.; Singh, Manjeet; Kharab, Rajesh

    2012-06-01

    We have studied the effects of nuclear induced breakup channel coupling on the fusion cross-section for 6Li+12C and 6He+12C systems in the near barrier energy regime using the dynamic polarization potential (DPP) approach. It has been found that there is enhancement in the fusion cross-section with respect to standard one-dimensional barrier penetration model in the below barrier energy regime while at energies above the barrier there is suppression of fusion cross-section with respect to simple barrier penetration model is observed. The agreement between data and predictions for 6Li+12C system improves significantly as a result of the inclusion of nuclear induced DPP.

  19. /sup 12/C(/sup 6/Li,d)/sup 16/O. -->. cap alpha. +/sup 12/C reaction mechanism by means of angular correlation measurements

    SciTech Connect

    Cunsolo, A.; Foti, A.; Imme, G.; Pappalardo, G.; Raciti, G.; Saunier, N.

    1980-06-01

    The particle-particle angular correlation method is applied to the reaction /sup 12/C(/sup 6/Li,d)/sup 16/O ..-->.. ..cap alpha..+/sup 12/C. Deuterons were detected at theta/sup lab//sub d/=10/sup 0/. Information on the reaction mechanism is obtained by analyzing the shape and the angular shift of the experimental data. A dominant direct transfer mechanism is found for the primary reaction. The ratios GAMMA..cap alpha../sub 0//GAMMA and the ..cap alpha..-reduced widths ..gamma cap alpha../sub 0/ are deduced.

  20. The Nucleus Introduced

    PubMed Central

    Pederson, Thoru

    2011-01-01

    Now is an opportune moment to address the confluence of cell biological form and function that is the nucleus. Its arrival is especially timely because the recognition that the nucleus is extremely dynamic has now been solidly established as a paradigm shift over the past two decades, and also because we now see on the horizon numerous ways in which organization itself, including gene location and possibly self-organizing bodies, underlies nuclear functions. PMID:20660024

  1. 99.996 %{sup 12}C films isotopically enriched and deposited in situ

    SciTech Connect

    Dwyer, K. J.; Pomeroy, J. M.; Simons, D. S.

    2013-06-24

    Ionizing natural abundance carbon dioxide gas, we extract and mass select the ions, depositing thin films isotopically enriched to 99.9961(4) %{sup 12}C as measured by secondary ion mass spectrometry (SIMS). In solid state quantum information, coherence times of nitrogen-vacancy (NV) centers in {sup 12}C enriched diamond exceeding milliseconds demonstrate the viability of NV centers as qubits, motivating improved isotopic enrichment. NV centers in diamond are particularly attractive qubit candidates due to the optical accessibility of the spin states. We present SIMS analysis and cross-sectional scanning electron microscopy of {sup 12}C enriched thin film samples grown with this method.

  2. Astrophysical SE2 factor of the 12C(α, γ)16O reaction through the 12C(11B, 7Li)16O transfer reaction

    NASA Astrophysics Data System (ADS)

    Guo, B.; Du, X. C.; Li, Z. H.; Li, Y. J.; Pang, D. Y.; Su, J.; Yan, S. Q.; Fan, Q. W.; Gan, L.; Han, Z. Y.; Li, E. T.; Li, X. Y.; Lian, G.; Liu, J. C.; Pei, C. J.; Qiao, L. H.; Shen, Y. P.; Su, Y.; Wang, Y. B.; Zeng, S.; Zhou, Y.; Liu, W. P.

    2016-02-01

    The 12C(α, γ)16O reaction plays a key role in the evolution of stars with masses of M > 0.55 M⊙. At the Gamow peak (Ec.m. = 300 ke V, T9 = 0.2), the cross section of the 12C(α, γ)16O reaction is so small (about 10-17 barn) that the direct measurement in ground laboratory is not feasible with the existing technology. Up to now, the cross sections at lower energies can only be extrapolated from the data at higher energies. However, two subthreshold resonances, locating at Ex = 7.117 MeV and Ex = 6.917 MeV, make this extrapolation more complicated. In this work the 6.917 MeV subthreshold resonance in the 12C(α, γ)16O reaction was investigated via the 12C(11B, 7Li)16O reaction. The experiment was performed using the Q3D magnetic spectrograph at HI-13 tandem accelerator. We measured the angular distribution of the 12C(11B, 7Li)16O transfer reaction leading to the 6.917 MeV state. Based on DWBA analysis, we derived the square of ANC of the 6.917 MeV level in 16O to be (2.45± 0.28) ×1010 fm-1, with which the reduced-α width can be computed. Finally, we calculated the astrophysical SE2 factor of the 6.917 MeV resonance to be 67.6 ± 7.7 ke V b.

  3. Computational Models of X-Ray Burst Quenching Times and 12C Nucleosynthesis Following a Superburst

    SciTech Connect

    Fisker, J L

    2009-03-19

    Superbursts are energetic events on neutron stars that are a thousand times more powerful than ordinary type I X-ray bursts. They are believed to be powered by a thermonuclear explosion of accumulated {sup 12}C. However, the source of this {sup 12}C remains elusive to theoretical calculations and its concentration and ignition depth are both unknown. Here we present the first computational simulations of the nucleosynthesis during the thermal decay of a superbust, where X-ray bursts are quenched. Our calculations of the quenching time verify previous analytical calculations and shed new light on the physics of stable burning at low accretion rates. We show that concentrated (X{sub {sup 12}C} {approx}> 0.40), although insufficient, amounts of {sup 12}C are generated during the several weeks following the superburst where the decaying thermal flux of the superburst stabilizes the burning of the accreted material.

  4. Triangular D3h Symmetry in the Rotation-Vibration Spectrum of 12C

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2015-02-01

    Our recent measurements of new states in 12C including the second 2+ at 10 MeV and the high spin 5- state at 22.4 MeV allow us to study the Rotation-Vibration spectrum of 12C from which evidence for a new (D3h) geometrical symmetry emerges. The data fit very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4+/-, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D3h symmetry was observed in triatomic molecules, and it is observed in 12C for the first time in nuclear physics. The triatomic like structure in nuclei is reminiscent of the discovery of diatomic α+14C structure in 18O. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or non observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.654 MeV in 12C.

  5. Further evidence for a dynamically generated secondary bow in 13C+12C rainbow scattering

    NASA Astrophysics Data System (ADS)

    Ohkubo, S.; Hirabayashi, Y.; Ogloblin, A. A.

    2015-11-01

    The existence of a secondary bow is confirmed for 13C+12C nuclear rainbow scattering in addition to the 16O+12C system. This is found by studying the experimental angular distribution of 13C+12C scattering at the incident 13C energy EL=250 MeV with an extended double-folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic wave functions for 12C using a density-dependent nucleon-nucleon force. The Airy minimum at θ ≈70°, which is not reproduced by a conventional folding potential, is revealed to be a secondary bow generated dynamically by a coupling to the excited state 2+ (4.44 MeV) of 12C. The essential importance of the quadruple Y 2 term (reorientation term) of potential of the excited state 2+ of 12C for the emergence of a secondary bow is found. The mechanism of the secondary bow is intuitively explained by showing how the trajectories are refracted dynamically into the classically forbidden angular region beyond the rainbow angle of the primary rainbow.

  6. Phenomenological analysis of rapidity distribution of negative pions in central 12C+12C collisions at $\\sqrt{s_{nn}} = 3.14\\, {\\rm GeV}$

    NASA Astrophysics Data System (ADS)

    Olimov, Khusniddin K.; Ali, Qasim; Haseeb, Mahnaz Q.; Arif, Atif; Lutpullaev, Sagdulla L.; Yuldashev, B. S.

    2015-06-01

    Various aspects of the simple phenomenological model, the grand combinational model (GCM), proposed earlier for the systematic description of the center-of-mass (cm) rapidity distributions of different particles produced in high energy heavy ion collisions, were analyzed. The values of GCM parameters were extracted from fitting the cm rapidity distributions of the negative pions in 12C+12C collisions at √ {snn} = 3.14 GeV both in the experiment and using Modified FRITIOF Model. The GCM parameters extracted for the central 12C+12C collisions were compared with those obtained in central Pb+Pb collisions at super proton synchrotron (SPS) and alternating gradient synchrotron (AGS) energies between √ {snn} = 6.3 GeV and √ {snn} = 12.3 GeV and in central Au+Au collisions at Relativistic heavy ion collider (RHIC) energies between √ {snn} = 19.6 GeV and √ {snn} = 200 GeV. The plausible physical interpretations for the GCM parameters were given. The initial assumption that the parameter β of GCM should be zero for symmetric systems with identical colliding nuclei was validated. The parameter γ of GCM was deduced to follow an approximate asymptotic behavior (γ → 0 as √ {snn} -> ∞ ) at very large cm energies, and γ ≅ 0 could possibly be related to complete dehadronization of the whole collision system, along with attaining its maximum possible energy density, in central collisions of identical nuclei. The behavior of cm energy dependence of γ suggested that it could possibly be sensitive to deconfinement phase transition.

  7. Excitation functions of inelastic and transfer channels in {sup 12}C+{sup 12}C around E{sub c.m.}=32.5 MeV

    SciTech Connect

    Szilner, S.; Basrak, Z.

    1997-03-01

    A prominent and wide resonance centered at E{sub c.m.}=32.5 MeV has recently been found in the (0{sub 2}{sup +},0{sub 2}{sup +}) inelastic channel of the {sup 12}C+{sup 12}C reaction. It has been suggested that it corresponds to a 6{alpha}-particle-chain state in {sup 24}Mg. In the present work we study {sup 12}C+{sup 12}C excitation functions between center-of-mass energies of 30 and 35 MeV in steps of 250 keV for weakly populated outgoing channels. We present the inelastic channels to the states above the {alpha}-particle decay threshold, (0{sub 1}{sup +},0{sub 2}{sup +}), (0{sub 1}{sup +},3{sub 1}{sup {minus}}), and (0{sub 1}{sup +},4{sub 1}{sup +}), and the one- and two-nucleon transfer channels. In the inelastic and the transfer channels we observe correlated intermediate-width structures at E{sub c.m.}=31, 32.5, and 33.5 MeV, whose widths are appreciably smaller than the width measured in the (0{sub 2}{sup +},0{sub 2}{sup +}) channel. Our E{sub c.m.}=32.5 MeV angular distribution of the (0{sub 1}{sup +},0{sub 2}{sup +}) channel exhibits oscillatory behavior and, unlike that of the (0{sub 2}{sup +},0{sub 2}{sup +}) channel, does not display enhancement around {theta}{sub c.m.}=90{degree}. Data were collected via the kinematic coincidence technique. For data reduction we use a novel approach allowing for the extraction of results on nonbinary channels. {copyright} {ital 1997} {ital The American Physical Society}

  8. Kaon-nucleus scattering

    NASA Technical Reports Server (NTRS)

    Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.

    1989-01-01

    The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

  9. Convergence of the nucleus-nucleus Glauber multiple scattering series

    SciTech Connect

    Usmani, A.A.; Ahmad, I. )

    1991-05-01

    The Glauber {ital S}-matrix operator for nucleus-nucleus scattering is expressed as a finite series of matrix elements involving Bell's polynomials. Analyzing {alpha}{sup 4}He elastic-scattering data at the incident momentum of 4.32 GeV/{ital c}, we infer that our expansion is appreciably converging. Further, by applying closure over target and projectile states and neglecting a certain class of terms involving intermediate excitations, we arrive at a recurrence relation for nucleus-nucleus multiple scattering series terms, which invites further study as it seems to provide a simple method for calculating the nucleus-nucleus elastic-scattering cross section.

  10. Nucleus Course in Japanese.

    ERIC Educational Resources Information Center

    Akiyama, Nobuo; Flamm, Carol S.

    The "Nucleus Course in Japanese," based on the Institute of Modern Languages'"Situational Reinforcement" approach, is designed for 80 to 100 hours of instruction. Each lesson has several sections--Response drills, Appropriate Response Sequence, and Reading. Most of the lessons also include optional sections with Sentences for Repetition or a…

  11. Cell nucleus in context

    SciTech Connect

    Lelievre, Sophie A.; Bissell, Mina J.; Pujuguet, Philippe

    1999-11-11

    The molecular pathways that participate in regulation of gene expression are being progressively unraveled. Extracellular signals, including the binding of extracellular matrix and soluble molecules to cell membrane receptors, activate specific signal transducers that convey information inside the cell and can alter gene products. Some of these transducers when translocated to the cell nucleus may bind to transcription complexes and thereby modify the transcriptional activity of specific genes. However, the basic molecules involved in the regulation of gene expression are found in many different cell and tissue types; thus the mechanisms underlying tissue-specific gene expression are still obscure. In this review, we focus on the study of signals that are conveyed to the nucleus. We propose that the way in which extracellular signals are integrated may account for tissue-specific gene expression. We argue that the integration of signals depends on the structural organization of cells ( i.e., extracellular matrix, cell membrane, cytoskeleton, nucleus) which a particular cell type within a tissue. Putting the nuclei in context allows us to envision gene expression as being regulated not only by the communication between the extracellular environment and the nucleus, but also by the influence of organized assemblies of cells on extracellular-nuclear communications.

  12. IMPROVED LINE DATA FOR THE SWAN SYSTEM {sup 12}C{sup 13}C ISOTOPOLOGUE

    SciTech Connect

    Ram, Ram S.; Brooke, James S. A.; Bernath, Peter F.; Sneden, Christopher; Lucatello, Sara E-mail: rr662@york.ac.uk E-mail: chris@verdi.as.utexas.edu

    2014-03-01

    We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the {sup 12}C{sup 13}C isotopologue Swan d{sup 3}Π-a{sup 3}Π system 0-0, 0–1, 0–2, 1–0, 1–1, 1–2, 2–0, 2–1, and 2–2 vibrational bands. The line positions and energy levels were predicted through new analyses of published laboratory data for the {sup 12}C{sup 13}C lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The {sup 12}C{sup 13}C line data were combined with similar data for {sup 12}C{sub 2,} reported in a companion paper, and applied to produce synthetic spectra of carbon-rich metal-poor stars that have strong C{sub 2} Swan bands. The matches between synthesized and observed spectra were used to estimate band head positions for a few of the {sup 12}C{sup 13}C vibrational bands and to verify that the new computed line data match observed spectra. The much weaker C{sub 2} lines of the bright red giant Arcturus were also synthesized in the band head regions.

  13. Binary reaction decays from {sup 24}Mg+{sup 12}C

    SciTech Connect

    Beck, C.; Papka, P.; Zafra, A. Sanchez i; Azaiez, F.; Bednarczyk, P.; Courtin, S.; Curien, D.; Dorvaux, O.; Lebhertz, D.; Nourreddine, A.; Rousseau, M.; Thummerer, S.; Oertzen, W. von; Gebauer, B.; Wheldon, C.; Kokalova, Tz.; Angelis, G. de; Gadea, A.; Lenzi, S.; Szilner, S.

    2009-09-15

    Charged-particle and {gamma} decays in {sup 24}Mg* are investigated for excitation energies where quasimolecular resonances appear in {sup 12}C+{sup 12}C collisions. Various theoretical predictions for the occurrence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured {sup 24}Mg* excitation energy region. The inverse kinematics reaction {sup 24}Mg+{sup 12}C is studied at E{sub lab}({sup 24}Mg)=130 MeV, an energy that enables the population of {sup 24}Mg states decaying into {sup 12}C+{sup 12}C resonant breakup states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with Euroball IV installed at the Vivitron tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions, and their associated {gamma} decays studied. Coincident events associated with inelastic and {alpha}-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body Q values. The analysis of the binary reaction channels is presented with a particular emphasis on {sup 24}Mg-{gamma}, {sup 20}Ne-{gamma}, and {sup 16}O-{gamma} coincidences. New information (spin and branching ratios) is deduced on high-energy states in {sup 24}Mg and {sup 16}O, respectively.

  14. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts...

  15. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts...

  16. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts...

  17. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts...

  18. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts...

  19. Onset of deconfinement in nucleus-nucleus collisions

    SciTech Connect

    Gazdzicki, M.; Gorenstein, M. I.; Seyboth, P.

    2012-05-15

    The energy dependence of hadron production in relativistic nucleus-nucleus collisions reveals anomalies-the kink, horn, and step. They were predicted as signals of the deconfinement phase transition and observed by the NA49 Collaboration in central PbPb collisions at the CERN SPS. This indicates the onset of the deconfinement in nucleus-nucleus collisions at about 30 A GeV.

  20. The closo-Si12C12 molecule from cluster to crystal: A theoretical prediction

    NASA Astrophysics Data System (ADS)

    Duan, Xiaofeng F.; Burggraf, Larry W.

    2016-03-01

    The structure of closo-Si12C12 is unique among stable SinCm isomers (n, m > 4) because of its high symmetry, π-π stacking of C6 rings and unsaturated silicon atoms at symmetrical peripheral positions. Dimerization potential surfaces reveal various dimerization reactions that form between two closo-Si12C12 molecules through Si-Si bonds at unsaturated Si atoms. As a result the closo-Si12C12 molecule is capable of polymerization to form stable 1D polymer chains, 2D crystal layers, and 3D crystals. 2D crystal structures formed by side-side polymerization satisfy eight Si valences on each monomer without large distortion of the monomer structure. 3D crystals are formed by stacking 2D structures in the Z direction, preserving registry of C6 rings in monomer moiety.

  1. Experimental study of the 13C+12C fusion reaction at deep sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Tudor, D.; Chilug, A. I.; Straticiuc, M.; Trache, L.; Chesneanu, D.; Toma, S.; Ghita, D. G.; Burducea, I.; Margineanu, R.; Pantelica, A.; Gomoiu, C.; Zhang, N. T.; Tang, X.; Li, Y. J.

    2016-04-01

    Heavy-ion fusion reactions between light nuclei such as carbon and oxygen isotopes have been studied because of their significance for a wide variety of stellar burning scenarios. One important stellar reaction is 12C+12C, but it is difficult to measure it in the Gamow window because of very low cross sections and several resonances occurring. Hints can be obtained from the study of 13C+12C reaction. We have measured this process by an activation method for energies down to Ecm=2.5 MeV using 13C beams from the Bucharest 3 MV tandetron and gamma-ray deactivation measurements in our low and ultralow background laboratories, the latter located in a salt mine about 100 km north of Bucharest. Results obtained so far are shown and discussed in connection with the possibility to go even further down in energy and with the interpretation of the reaction mechanism at such deep sub-barrier energies.

  2. High Resolution Laser Spectroscopy of Mg12C12CD, Mg13C13CH and Mg12C_4H

    NASA Astrophysics Data System (ADS)

    Forthomme, D.; Linton, C.; Tokaryk, D. W.; Adam, A. G.; Granger, A. D.

    2010-06-01

    Carbon and magnesium are abundant elements in the interstellar medium, so it is possible that carbon chain molecules containing a magnesium atom may exist in this environment. With this in mind, radical molecules of the form MgC2nH (n = 1,2,3) have been frequent subjects of both experimental and theoretical studies In this presentation we will discuss our high-resolution experiments of the ~A2Π-~X2Σ+ transitions in the isotopologues Mg12C12CD and Mg13C13CH, which complement our earlier investigation of this spectrum in Mg12C12CH^b. The data permit us to determine the lengths of individual bonds to high precision. In addition, we have expanded on previous studies of the ~A2Π-~X2Σ+ transition of Mg12C_4H, conducted at medium resolution. The parameters obtained from our high-resolution spectra are compared with those obtained from theoretical structure calculations. H. Ding, C. Apetrei, L. Chacaga, J. P. Maier, Astrophys. J. 677 (2008) 348-352 D. W. Tokaryk, A. G. Adam, W. S. Hopkins, J. Mol. Spectrosc. 230 (2005) 54-61 D. E. Woon, Chem. Phys. Lett. 274 (1997) 299-305 C. A. Thompson and L. Andrews, J. Am. Chem. Soc. 118 (1996) 10242-10249 X. Guo, J. Zhang, J. Li, L. Jiang, J. Zhang, Chem. Phys 360 (2009) 27-31 E. Chasovskikh, E. B. Jochnowitz, J. P. Maier, J. Phys. Chem. A. 112 (2008) 8686-8689.

  3. Proton Nucleus Elastic Scattering Data.

    Energy Science and Technology Software Center (ESTSC)

    1993-08-18

    Version 00 The Proton Nucleus Elastic Scattering Data file PNESD contains the numerical data and the related bibliography for the differential elastic cross sections, polarization and integral nonelastic cross sections for elastic proton-nucleus scattering.

  4. 8Be Direct Transfer in α+12C Inelastic Scattering and Signatures of the Alpha Particle Condensation in the NEAR-3α Threshold States of 12C

    NASA Astrophysics Data System (ADS)

    Belyaeva, T. L.; Demyanova, A. S.; Ogloblin, A. A.; Goncharov, S. A.

    The coupled reaction channels model calculations of the direct 8Be transfer in the α+12C elastic and inelastic (to the 7.65 MeV 02^ + and the 9.65 MeV 31^ - states) scattering have been performed. It is shown that the cluster configuration with zero relative angular momentum dominates in 02^ + state being 4.4 times larger than that in the ground state. In the 31^ - state, a dominance of the p-orbital motion is found. The condensed properties are confirmed in the Hoyle state. The 3α exotic, but hardly a condensed structure of the 31^ - state is found.

  5. {sup 12}C-{sup 12}C elastic scattering at 1.016, 1.449, and 2.4 GeV and the NN amplitude

    SciTech Connect

    Chauhan, Deeksha; Khan, Z. A.

    2007-05-15

    Working within the framework of the Coulomb modified Glauber model, we analyze the elastic angular distribution and reaction cross section for the {sup 12}C-{sup 12}C system at 1.016, 1.449, and 2.4 GeV. The elastic S matrix is evaluated using the effective profile function approach, and a correlation expansion for the Glauber amplitude is obtained. We emphasize the parametrization of the basic (input) NN amplitude, which may be used for a wide range of angles. Retaining the first two terms of the correlation expansion and using the realistic densities for the colliding nuclei, we find that (i) the consideration of higher momentum transfer components, and hence the nondiffractive behavior, of the NN amplitude provides a more satisfactory account of the data than does the conventional (one-term) Gaussian parametrization for the NN amplitude, (ii) the in-medium effects seem to reduce the (free) NN total cross section and influence the other parameters of the NN amplitude as well, (iii) the phase of the NN amplitude does not help in improving the theoretical situation, and (iv) the c.m. correlations play an important role at the energies considered. We also discuss the suitability of the effective profile function approach in the present context.

  6. Role of 8Be heavy stripping mechanism in the α + 12C inelastic scattering to the near-3 α-threshold states in 12C

    NASA Astrophysics Data System (ADS)

    Belyaeva, T. L.; Danilov, A. N.; Demyanova, A. S.; Goncharov, S. A.; Ogloblin, A. A.; Perez-Torres, R.

    2011-11-01

    The angular distributions of α + 12C elastic and inelastic (to the 4.44 MeV, 2+; 7.65MeV, 0+; and 9.64MeV, 3- states) scattering at 110 MeV are characterized by pronounced enhancement and strong oscillations at large angles. We performed calculations of the differential cross sections of these reactions assuming a potential scattering in the forward hemisphere and the direct transfer of 8Be cluster θ c.m. > 90°. We showed that the α + 8Be cluster configuration with relative angular momentum L = 0 dominates in the Hoyle state being 4.4 times larger than that in the ground state. This result also contributes to the verification of αBEC hypothesis and is consistent with the conjecture of a dilute 3 α structure of the Hoyle state. In the 9.64 MeV, 3- state, a positive interference of all allowed α + 8Be configurations with a dominance of the p-orbital (49%) α-8Be relative motion is found. This finding manifests the exotic 3 α, but hardly condensed structure of the 9.64-MeV 3- state in 12C.

  7. Role of {sup 8}Be heavy stripping mechanism in the {alpha} + {sup 12}C inelastic scattering to the near-3{alpha}-threshold states in {sup 12}C

    SciTech Connect

    Belyaeva, T. L.; Danilov, A. N.; Demyanova, A. S.; Goncharov, S. A.; Ogloblin, A. A.; Perez-Torres, R.

    2011-11-15

    The angular distributions of {alpha} + {sup 12}C elastic and inelastic (to the 4.44 MeV, 2{sup +}; 7.65MeV, 0{sup +}; and 9.64MeV, 3{sup -} states) scattering at 110 MeV are characterized by pronounced enhancement and strong oscillations at large angles. We performed calculations of the differential cross sections of these reactions assuming a potential scattering in the forward hemisphere and the direct transfer of {sup 8}Be cluster {theta}{sub c.m.} > 90 Degree-Sign . We showed that the {alpha} + {sup 8}Be cluster configuration with relative angular momentum L = 0 dominates in the Hoyle state being 4.4 times larger than that in the ground state. This result also contributes to the verification of {alpha}BEC hypothesis and is consistent with the conjecture of a dilute 3{alpha} structure of the Hoyle state. In the 9.64 MeV, 3{sup -} state, a positive interference of all allowed {alpha} + {sup 8}Be configurations with a dominance of the p-orbital (49%) {alpha}-{sup 8}Be relative motion is found. This finding manifests the exotic 3{alpha}, but hardly condensed structure of the 9.64-MeV 3{sup -} state in {sup 12}C.

  8. Development of the Silicon Array at Notre Dame (SAND) for the Study of the 12C + 12C Reaction at Sub-Coulomb Energies

    NASA Astrophysics Data System (ADS)

    Cahillane, Craig

    2011-10-01

    The 12C + 12C fusion reaction is an important process in stellar evolution and nucleosynthesis. The energy region of interest lies between 1 and 3 MeV, but studying the reaction at these energies is difficult because of the reaction's rapidly decaying cross-section a sub-Coulomb energies. Both detector efficiency and beam intensity limit such measurements. As a test run for the future Silicon Array at Notre Dame (SAND), two YY1 Trapezoid Silicon Detectors were used to detect the proton decay of the carbon fusion reaction. The two detectors covered a solid angle of 0.34 steradians. In the construction of SAND, more large surface area silicon detectors will be used to dramatically increase detection efficiency by covering a much larger solid angle. Combined with the new high-intensity 5 MV accelerator also under construction at Notre Dame, SAND could reduce the error on low energy cross sections in the astrophysical region and possibly detect hypothesized resonances at lower energies. This work is supported by the NSF under Grant No. PHY-1068192 and PHY-0822648.

  9. Effect of {sup 12}C+{sup 12}C reaction and convective mixing on the progenitor mass of ONe white dwarfs

    SciTech Connect

    Halabi, Ghina M. El Eid, Mounib

    2015-02-24

    Stars in the mass range ∼8 - 12 M{sub ⊙} are the most numerous massive stars. This mass range is critical because it may lead to supernova (SN) explosion, so it is important for the production of heavy elements and the chemical evolution of the galaxy. We investigate the critical transition mass (M{sub up}), which is the minimum initial stellar mass that attains the conditions for hydrostatic carbon burning. Stars of masses < M{sub up} evolve to the Asymptotic Giant Branch and then develop CO White Dwarfs, while stars of masses ≥ M{sub up} ignite carbon in a partially degenerate CO core and form electron degenerate ONe cores. These stars evolve to the Super AGB (SAGB) phase and either become progenitors of ONe White Dwarfs or eventually explode as electron-capture SN (EC-SN). We study the sensitivity of M{sub up} to the C-burning reaction rate and to the treatment of convective mixing. In particular, we show the effect of a recent determination of the {sup 12}C+{sup 12}C fusion rate, as well as the extension of the convective core during hydrogen and helium burning on M{sub up} in solar metallicity stars. We choose the 9 M{sub ⊙} model to show the detailed characteristics of the evolution with the new C-burning rate.

  10. 33 CFR 157.12c - Construction, maintenance, security, calibration, and training.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... RELATING TO TANK VESSELS CARRYING OIL IN BULK Design, Equipment, and Installation § 157.12c Construction, maintenance, security, calibration, and training. (a) The oil discharge monitoring and control system must be designed to ensure that user access is restricted to essential controls. Access beyond these controls...

  11. {sup 15}N(p,{alpha}{sub 0}){sup 12}C S factor

    SciTech Connect

    Barker, F. C.

    2008-10-15

    Experimental values of the astrophysical S factor for the {sup 15}N(p,{alpha}{sub 0}){sup 12}C reaction are available both from direct measurements and from the Trojan horse method. We here use R-matrix formulas to fit these values and to extrapolate to zero energy to obtain values of S(0)

  12. Selective Targeting of the KRAS G12C Mutant: Kicking KRAS When It's Down.

    PubMed

    Hobbs, G Aaron; Wittinghofer, Alfred; Der, Channing J

    2016-03-14

    Two recent studies evaluated a small molecule that specifically binds to and inactivates the KRAS G12C mutant. The new findings argue that the perception that mutant KRAS is persistently frozen in its active GTP-bound form may not be accurate. PMID:26977877

  13. Are we there yet? A Practitioner's View of DO-178C/ED-12C

    NASA Astrophysics Data System (ADS)

    Daniels, Dewi

    RTCA DO-178B/EUROCAE ED-12B is the industry-accepted guidance for determining that the software aspects of airborne systems and equipment comply with airworthiness requirements. DO-178B/ED-12B, published in 1992, is being updated to DO-178C/ED-12C. Nearly six years in the making, DO- 178C/ED-12C is expected to be completed in December 2010. It will be accompanied by a new set of supplements providing additional and much-needed guidance on tool qualification, model based development and verification, objectoriented technologies, and formal methods. Written by a member of the DO-178C/ED-12C editorial team who is also a practising software developer and verifier, this paper provides a practitioner's view of the new standard and its supplements. It explains how they will affect your organisation, focusing on the practical implications of the many changes between DO-178B/ED-12B and DO-178C/ED-12C.

  14. GRH Characterization using 4.4 MeV ^12C Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Herrmann, H. W.; Langenbrunner, J. R.; Young, C. S.; Barton, B. T.; Mack, J. M.; McEvoy, A. M.; Evans, S.; Sedillo, T.; Stoeffl, W.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Grafil, E.

    2010-11-01

    The OMEGA Gamma Reaction History (GRH) diagnostic has been characterized using a relatively well-known source of 4.43 MeV gamma rays produced from inelastic scattering of DT-neutrons off of a graphite puck placed near an imploding capsule at the OMEGA laser facility. An independently measured neutron yield, combined with the known ^12C density and ^12C(n,n'γ)^12C cross-section, allows an in-situ calibration of the GRH detection efficiency at 4.43 MeV. GRH data were collected at two different ^12C target locations to confirm the published angular distribution of gamma rays and were compared with MCNP modeling predictions. These in-situ calibrations were used to validate the GRH simulation code based on a coupled MCNP/ACCEPT Monte-Carlo method. By combining these results with other absolute calibration methods, we are able to infer a DT branching ratio for gamma to neutron production and to make an accurate plastic ablator areal density measurement.

  15. Towards Understanding the DO-178C / ED-12C Assurance Case

    NASA Technical Reports Server (NTRS)

    Holloway, C M.

    2012-01-01

    This paper describes initial work towards building an explicit assurance case for DO-178C / ED-12C. Two specific questions are explored: (1) What are some of the assumptions upon which the guidance in the document relies, and (2) What claims are made concerning test coverage analysis?

  16. Ethane's 12C/13C Ratio in Titan: Implications for Methane Replenishment

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Nixon, C. A.; Romani, P. N.; Bjoraker, G. L.; Sada, P. V.; Lunsford, A. W.; Boyle, R. J.; Hesman, B. E.; McCabe, G. H.

    2009-01-01

    As the .main destination of carbon in the destruction of methane in the atmosphere of Titan, ethane provides information about the carbon isotopic composition of the reservoir from which methane is replenished. If the amount of methane entering the atmosphere is presently equal to the amount converted to ethane, the 12C/13C ratio in ethane should be close to the ratio in the reservoir. We have measured the 12C/13C ratio in ethane both with Cassini CIRS(exp 1) and from the ground and find that it is very close to the telluric standard and outer planet values (89), consistent with a primordial origin for the methane reservoir. The lower 12C/13C ratio measured for methane by Huygens GCMS (82.3) can be explained if the conversion of CH4 to CH3 (and C2H6) favors 12C over 13C with a carbon kinetic isotope effect of 1.08. The time required for the atmospheric methane to reach equilibrium, i.e., for replenishment to equal destruction, is approximately 5 methane atmospheric lifetimes.

  17. Interaction of (12)C ions with the mouse retinal response to light.

    PubMed

    Carozzo, Simone; Ball, Sherry L; Narici, Livio; Schardt, Dieter; Sannita, Walter G

    2015-06-26

    Astronauts in orbit reported phosphenes varying in shape and orientation across the visual field; incidence was correlated with the radiation flux. Patients with skull tumors treated by (12)C ions and volunteers whose posterior portion of the eye was exposed to highly ionizing particles in early studies reported comparable percepts. An origin in radiation activating the visual system is suggested. Bursts (∼ 4 ms) of (12)C ions evoked electrophysiological mass responses comparable to those to light in the retina of anesthetized wild-type mice at threshold flux intensities consistent with the incidence observed in humans. The retinal response amplitude increased in mice with ion intensity to a maximum at ∼ 2000 ions/burst, to decline at higher intensities; the inverted-U relationship suggests complex effects on retinal structures. Here, we show that bursts of (12)C ions presented simultaneously to white light stimuli reduced the presynaptic mass response to light in the mouse retina, while increasing the postsynaptic retinal and cortical responses amplitude and the phase-locking to stimulus of cortical low frequency and gamma (∼ 25-45 Hz) responses. These findings suggest (12)C ions to interfere with, rather than mimicking the light action on photoreceptors; a parallel action on other retinal structures/mechanisms resulting in cortical activation is conceivable. Electrophysiological visual testing appears applicable to monitor the radiation effects and in designing countermeasures to prevent functional visual impairment during operations in space. PMID:25956035

  18. Experimental evidence for a fusion enhancement in 19O+12C at near barrier energies

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Steinbach, T. K.; Vadas, J.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Tripathi, V.; Kuvin, S. A.; Wiedenhover, I.; Umar, A. S.; Oberacker, V. E.

    2016-03-01

    Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for 18O and 19O nuclei incident on a 12C target. A beam of 19O was produced by the 18O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting 19O beam bombarded a 100 μg/cm2 12C target at an intensity of 2-4 x 104p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Evaporation residues were detected with high efficiency by measuring them in the angular range 4.4° <=θlab <= 11.7°. The fusion cross-section has been measured down to 170 mb level. As compared to 18O+12C the fusion cross-section for 19O+12C is enhanced by approximately a factor of 3 times at the lowest energy measured. The measured excitation function will be compared with theoretical calculations. Supported by the US DOE under Grant No. DEFG02-88ER-40404.

  19. A = 10 nuclei and 12C with SRG evolved chiral three-nucleon interactions

    NASA Astrophysics Data System (ADS)

    Maris, Pieter; Vary, James; Calci, Angelo; Langhammer, Joachim; Binder, Sven; Roth, Robert

    2014-09-01

    We investigate selected static and transition properties of A = 10 nuclei and 12C using ab initio No-Core Shell Model (NCSM) methods with chiral two- and SRG-evolved three-nucleon interactions. We examine the dependences of observables on the SRG evolution scale and on the model-space parameters. We obtain nearly converged low-lying excitation spectra for 12C. We compare results of the full NCSM with the Importance Truncated NCSM in large model spaces for benchmarking purposes in 12C. The agreement of some observables with experiment is improved significantly by the inclusion of 3N interactions, e.g., the B(M1) from the first (Jπ , T) = (1+ , 1) state to the ground state of 12C. However, in some cases the agreement deteriorates, e.g., for the excitation energy of the first (1+ , 0) state, leaving room for improved next-generation chiral Hamiltonians. On the other hand, the excitation energies of 10C, 10B, and 10Be are not as well converged as those of 12C. In particular the lowest two (1+ , 0) states of 10B are sensitive to both the basis truncation parameters and the 3N interaction. We investigate selected static and transition properties of A = 10 nuclei and 12C using ab initio No-Core Shell Model (NCSM) methods with chiral two- and SRG-evolved three-nucleon interactions. We examine the dependences of observables on the SRG evolution scale and on the model-space parameters. We obtain nearly converged low-lying excitation spectra for 12C. We compare results of the full NCSM with the Importance Truncated NCSM in large model spaces for benchmarking purposes in 12C. The agreement of some observables with experiment is improved significantly by the inclusion of 3N interactions, e.g., the B(M1) from the first (Jπ , T) = (1+ , 1) state to the ground state of 12C. However, in some cases the agreement deteriorates, e.g., for the excitation energy of the first (1+ , 0) state, leaving room for improved next-generation chiral Hamiltonians. On the other hand, the excitation

  20. Study of the reactions occurring in the fusion of {sup 12}C and {sup 16}O with heavy nuclei at incident energies below 10 MeV/nucleon

    SciTech Connect

    Cavinato, M.; Fabrici, E.; Gadioli, E.; Gadioli Erba, E.; Vergani, P.; Crippa, M.; Colombo, G.; Redaelli, I.; Ripamonti, M.

    1995-11-01

    The excitation functions for production of many residues in the fusion of {sup 12}C with {sup 181}Ta and {sup 197}Au and of {sup 16}O with {sup 165}Ho and {sup 181}Ta have been measured at incident energies varying from the Coulomb barrier up to about 10 MeV/nucleon. The cross sections for fusion of these ions without fission have been deduced and they show that such a process may only occur for projectile angular momenta smaller than a critical value. The excitation functions for individual reactions provide evidence for the emission of preequilibrium nucleons during the thermalization of the composite nucleus and may be satisfactorily reproduced by a calculation based on the Boltzmann master equation theory.

  1. Investigating {sup 13}C+{sup 12}C reaction by the activation method. Sensitivity tests

    SciTech Connect

    Chesneanu, Daniela Trache, L.; Margineanu, R.; Pantelica, A.; Ghita, D.; Straticiuc, M.; Burducea, I.; Blebea-Apostu, A. M.; Gomoiu, C. M.; Tang, X.

    2015-02-24

    We have performed experiments to check the limits of sensitivity of the activation method using the new 3 MV Tandetron accelerator and the low and ultra-low background laboratories of the “Horia Hulubei” National Institute of Physics and Nuclear Engineering (IFIN-HH). We have used the {sup 12}C+{sup 13}C reaction at beam energies E{sub lab}= 6, 7 and 8 MeV. The knowledge of this fusion cross section at deep sub-barrier energies is of interest for astrophysical applications, as it provides an upper limit for the fusion cross section of {sup 12}C+{sup 12}C over a wide energy range. A {sup 13}C beam with intensities 0.5–2 particleμA was provided by the accelerator and used to bombard graphite targets, resulting in activation with {sup 24}Na from the {sup 12}C({sup 13}C,p) reaction. The 1369 and 2754 keV gamma-rays from {sup 24}Na de-activation were clearly observed in the spectra obtained in two different laboratories used for measurements at low and ultralow background: one at the surface and one located underground in the Unirea salt mine from Slanic Prahova, Romania. In the underground laboratory, for E{sub lab} = 6 MeV we have measured an activity of 0.085 ± 0.011 Bq, corresponding to cross sections of 1–3 nb. This demonstrates that it is possible to measure {sup 12}C targets irradiated at lower energies for at least 10 times lower cross sections than before β–γ coincidences will lead us another factor of 10 lower, proving that this installations can be successfully used for nuclear astrophysics measurements.

  2. Investigating 13C +12C reaction by the activation method. Sensitivity tests

    NASA Astrophysics Data System (ADS)

    Chesneanu, Daniela; Trache, L.; Margineanu, R.; Pantelica, A.; Ghita, D.; Straticiuc, M.; Burducea, I.; Blebea-Apostu, A. M.; Gomoiu, C. M.; Tang, X.

    2015-02-01

    We have performed experiments to check the limits of sensitivity of the activation method using the new 3 MV Tandetron accelerator and the low and ultra-low background laboratories of the "Horia Hulubei" National Institute of Physics and Nuclear Engineering (IFIN-HH). We have used the 12C +13C reaction at beam energies Elab= 6, 7 and 8 MeV. The knowledge of this fusion cross section at deep sub-barrier energies is of interest for astrophysical applications, as it provides an upper limit for the fusion cross section of 12C +12C over a wide energy range. A 13C beam with intensities 0.5-2 particleμA was provided by the accelerator and used to bombard graphite targets, resulting in activation with 24Na from the 12C (13C ,p) reaction. The 1369 and 2754 keV gamma-rays from 24Na de-activation were clearly observed in the spectra obtained in two different laboratories used for measurements at low and ultralow background: one at the surface and one located underground in the Unirea salt mine from Slanic Prahova, Romania. In the underground laboratory, for Elab = 6 MeV we have measured an activity of 0.085 ± 0.011 Bq, corresponding to cross sections of 1-3 nb. This demonstrates that it is possible to measure 12C targets irradiated at lower energies for at least 10 times lower cross sections than before β-γ coincidences will lead us another factor of 10 lower, proving that this installations can be successfully used for nuclear astrophysics measurements.

  3. Synthesis, crystal structure, and properties of two modifications of MgB(12)C(2).

    PubMed

    Adasch, Volker; Hess, Kai-Uwe; Ludwig, Thilo; Vojteer, Natascha; Hillebrecht, Harald

    2007-01-01

    Single crystals of two modifications of the new magnesium boride carbide MgB(12)C(2) were synthesized from the elements in a metallic melt by using tantalum ampoules. Crystals were characterized by single-crystal X-ray diffraction and electron microprobe analysis (energy-dispersive (EDX) and wavelength-dispersive (WDX) X-ray spectroscopy). Orthorhombic MgB(12)C(2) is formed in a Cu/Mg melt at 1873 K. The crystal structure of o-MgB(12)C(2) (Imma, Z=4, a=5.6133(10), b=9.828(2), c=7.9329(15) A, 574 reflections, 42 variables, R(1)(F)=0.0208, wR(2)(I)=0.0540) consists of a hexagonal primitive array of B(12) icosahedra with Mg atoms and C(2) units in trigonal-prismatic voids. Each icosahedron has six exohedral B--B and six B--C bonds. Carbon is tetrahedrally coordinated by three boron atoms and one carbon atom with a remarkably long C--C distance of 1.727 A. Monoclinic MgB(12)C(2) is formed in an Al/Mg melt at 1573 K. The structure of m-MgB(12)C(2) (C2/c, Z=4, a=7.2736(11), b=8.7768(13), c=7.2817(11) A, beta=105.33(3) degrees , 1585 reflections, 71 variables, R(1)(F)=0.0228, wR(2)(I)=0.0610) may be described as a distorted cubic close arrangement of B(12) icosahedra. Tetrahedral voids are filled by C atoms and octahedral voids are occupied by Mg atoms. The icosahedra are interconnected by four exohedral B--B bonds to linear chains and by eight interstitial C atoms to form a three-dimensional covalent network. Both compounds fulfill the electron-counting rules of Wade and Longuet-Higgins. PMID:17236227

  4. Geometric and electronic structures of B12C6N6 fullerene

    NASA Astrophysics Data System (ADS)

    Li, Fei; Zhang, Yan; Chen, Hongshan

    2014-02-01

    An electron deficient fullerene B12C6N6 is studied by using ab initio calculations. The structure is generated by replacing N with C in the B12N12 cage to ensure only B-C and B-N bonds are formed. All the possible isomers are optimized and the low energy structures are determined. C and N atoms in the low energy isomers are inclined to segregate and form B2C2 and B2N2 squares. Natural bond analysis shows that the atomic orbitals of B, C and N in this cage hybrid approximately in sp2.3 and then form B-C and B-N bonds. The 2p orbitals perpendicular to the cage surface are partially occupied and the molecular orbitals formed by these orbitals are highly delocalized. The natural charge on N is about -1.17 in both B12N12 and B12C6N6, and the charge on C is -0.72 to -0.60. The molecular orbital compositions show that the B-N bonds are the same in B12N12 and B12C6N6, and the B-C bonds possess stronger covalent character. The HOMO of B12C6N6 is formed by 2p of B and C, and the LUMO is formed by 2p of C. The energy gap of C24, B12N12 and B12C6N6 is 2.52, 6.84 and 3.22 eV, respectively.

  5. In-medium effect with muon-neutrino and anti-muon-neutrino quasi-elastic scattering from 12C nucleons

    NASA Astrophysics Data System (ADS)

    Cheoun, Myung-Ki; Kim, K. S.; Kim, Hungchong; So, W. Y.; Maruyama, Tomoyuki; Kajino, Toshitaka

    2015-04-01

    We investigated the in-medium effect by density-dependent axial and weak-vector form factors on muon-neutrino ({{ν }μ }) and anti-muon-neutrino ({{\\bar{ν }}μ }) scattering in the quasi-elastic (QE) region from nucleons (N*) bound in a nucleus or immersed in a nuclear medium via neutral current (NC) and charged current (CC). For the density-dependent form factors, we exploited a quark-meson-coupling (QMC) model. We found that the {{ν }μ }({{\\bar{ν }}μ })-{{N}*} scattering cross sections via NC in the QE region usually decrease with an increased medium density, while those using CC were increased. However, their rate of change was sensitive to the four-momentum transfer given to a bound nucleon through scattering. We compared these results obtained by the elementary process corrected by the in-medium effect to the BNL and MiniBooNE data, which measured {{ν }μ } scattering cross sections per nucleon through {{ν }μ } - 12C scattering in 12C composite targets. The incident energy range was 550 \\lt {{E}ν }\\lt 3000 MeV. We increased the energy up to 100 GeV to compare our results to the NOMAD experimental data. In order to study the density effects on a nucleon embedded in 12C, we exploited the QMC form factors evaluated at ρ =0.5{{ρ }o}, where the normal density {{ρ }o}˜ 0.15 f{{m}-3}. The strangeness contributions in NC scattering are also incorporated into the form factors for comparison with experimental data. Our numerical results show that most of the experimental data can be explained in a satisfactory manner by the density-dependent elementary process, but there are some remaining deviations resulting from the nuclear structure, particularly in the low and high momentum-transfer regions.

  6. 12C(16O, α)24Mg* reaction in the energy region Ec.m.=26.6 to 42.9 MeV

    NASA Astrophysics Data System (ADS)

    Bechara, M. J.; Lazzarini, A. J.; Ledoux, R. J.; Cosman, E. R.

    1983-04-01

    The 12C+16O resonance structure in the 28Si nucleus is examined by means of the 12C(16O, α)24Mg reaction excitation functions in the energy range Ec.m.=26.6 to 42.9 MeV in 430 keV steps at θlab=7.5°. We could identify 64 discrete states in 24Mg up to 31.7 MeV of excitation energy. The excitation functions show abundant structure over the entire energy range. The summed excitation functions, which tend to average out statistical fluctuations, show pronounced intermediate structure enhancement in the cross section at Ec.m.~=29.5, 32.2, and 35 MeV and indicate the presence of a smaller peak at 37.3 MeV. The widths of these structures are about 1 MeV, which is intermediate between the value expected from ion-ion potential resonances and statistical fluctuations. The nonstatistical character of these structures is reinforced by some statistical tests and by the correlations in energy and width found in several exit channels. Our data also suggest a possible structural relationship between the 28Si resonances and certain 24Mg final states. NUCLEAR REACTIONS 12C(16O, α)24Mg* measured σ(E) to states up to 31.7 MeV of excitation energy for Ec.m.=26.6 to 42.9 MeV in 430 keV steps, θlab=7.5°. Nonstatistical structure observed.

  7. An analysis of the 12C(p,d) reaction at eta'(958) meson production region by microscopic transport model (JAM)

    NASA Astrophysics Data System (ADS)

    Higashi, Yuko; Ikeno, Natumi; Nagahiro, Hideko; Hirenzaki, Satoru; Fujioka, Hiroyuki; Itahashi, Kenta; Tanaka, Yoshiki

    2014-09-01

    We study theoretically the 12C(p , d) reaction for the formation of the η' mesonic nucleus to optimize the experiments at GSI and FAIR, where the missing mass spectroscopy of the 12C(p , d) reaction is adopted to measure η' meson bound states in 11C. This method was proposed in Ref. and the peak structures are expected in the inclusive spectra of the deuteron in case that the discrete states exist. The semi-exclusive measurements are also considered at FAIR to reduce the background, where protons/charged pions are measured in coincidence with the deuteron. We present the theoretical distributions of the emitted charged particle in the (p , d) reaction. The charged particles produced by the η' absorption are expected to have uniform angular distribution with the specific energy of the absorption process, while those by the background distribute in the forward directions. Thus, we can reduce the background largely by the differences of the charged particle distributions from these processes. We use the microscopic transport model and we report the advantages of the semi-exclusive measurements.

  8. Astrophysical S(E) factor of the {sup 15}N(p,{alpha}){sup 12}C reaction at sub-Coulomb energies via the Trojan horse method

    SciTech Connect

    La Cognata, M.; Romano, S.; Spitaleri, C.; Cherubini, S.; Crucilla, V.; Gulino, M.; Lamia, L.; Pizzone, R. G.; Tumino, A.; Tribble, R.; Fu, Changbo; Goldberg, V. Z.; Mukhamedzhanov, A. M.; Schmidt, D.; Tabacaru, G.; Trache, L.; Irgaziev, B. F.

    2007-12-15

    The low-energy bare-nucleus cross section for {sup 15}N(p,{alpha}){sup 12}C is extracted by means of the Trojan horse method applied to the {sup 2}H({sup 15}N,{alpha}{sup 12}C)n reaction at E{sub beam}=60 MeV. For the first time we applied the modified half-off-energy-shell resonant R-matrix method that takes into account off-energy-shell effects and initial- and final-state interactions. In particular it has been shown that inclusion of Coulomb {sup 15}N-d scattering and off-shell effects do not affect the determination of the astrophysical factor. Also the simple plane-wave approximation used in previous analyses is justified. The results extracted via the Trojan horse method are compared to direct data in the same energy region and show very good agreement in the energy interval 70-312 keV. These results confirm the extrapolations of the S factor reported in literature.

  9. Analytic optical potentials for nucleon-nucleus nucleus-nucleus collisions involving light and medium nuclei

    NASA Technical Reports Server (NTRS)

    Bidasaria, H. B.; Townsend, L. W.

    1982-01-01

    Utilizing an optical model potential approximation to the exact nucleus-nucleus multiple-scattering series, optical potentials for nucleon-nucleus and nucleus-nucleus collisions are analytically derived. These expressions are applicable to light and medium cosmic ray nuclei as their single-particle density distributions are analytically determined, without approximation, from their actual harmonic well charge density distributions. Pauli correlation effects are included through the use of a simple Gaussian function to replace the usual expression obtained in the infinite nuclear matter approximation.

  10. Nucleus from string theory

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Morita, Takeshi

    2011-08-01

    In generic holographic QCD, we find that baryons are bound to form a nucleus, and that its radius obeys the empirically-known mass-number (A) dependence r∝A1/3 for large A. Our result is robust, since we use only a generic property of D-brane actions in string theory. We also show that nucleons are bound completely in a finite volume. Furthermore, employing a concrete holographic model (derived by Hashimoto, Iizuka, and Yi, describing a multibaryon system in the Sakai-Sugimoto model), the nuclear radius is evaluated as O(1)×A1/3[fm], which is consistent with experiments.

  11. Neutrino-nucleus interactions

    SciTech Connect

    Gallagher, H.; Garvey, G.; Zeller, G.P.; /Fermilab

    2011-01-01

    The study of neutrino oscillations has necessitated a new generation of neutrino experiments that are exploring neutrino-nuclear scattering processes. We focus in particular on charged-current quasi-elastic scattering, a particularly important channel that has been extensively investigated both in the bubble-chamber era and by current experiments. Recent results have led to theoretical reexamination of this process. We review the standard picture of quasi-elastic scattering as developed in electron scattering, review and discuss experimental results, and discuss additional nuclear effects such as exchange currents and short-range correlations that may play a significant role in neutrino-nucleus scattering.

  12. Theoretical calculations for neutrino-induced charged current reactions in sup 12 C and recent experimental results

    SciTech Connect

    Mintz, S.L. ); Pourkaviani, M. )

    1989-12-01

    Theoretical calculations are presented for the reaction {nu}{sub {ital e}}+{sup 12}C{r arrow}{sup 12}N{sub g.s.} +{ital e}{sup {minus}} for {ital E}{sub {nu}} from threshold to 135 MeV, for the reaction {nu}{sub {mu}}+{sup 12}C{r arrow}{sup 12}N{sub g.s.} +{mu}{sup {minus}}, and the corresponding antineutrino reaction for {ital E}{sub {nu}} from threshold to 160 MeV. Use is made of updated form factors based on more recent data for {ital e}{sup {minus}}+{sup 12}C{r arrow}{sup 12}C{sup *}+{ital e}{prime} {minus} and {gamma}+{sup 12}C{r arrow}{sup 12}C{sup *}. The recent neutrino reaction experiments are discussed in light of these calculations.

  13. Higgs-Boson Production in Nucleus-Nucleus Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Cross section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  14. Higgs-boson production in nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W. (Principal Investigator)

    1990-01-01

    Cross-section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two-photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two-photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  15. Networking the nucleus

    PubMed Central

    Rajapakse, Indika; Scalzo, David; Tapscott, Stephen J; Kosak, Steven T; Groudine, Mark

    2010-01-01

    The nuclei of differentiating cells exhibit several fundamental principles of self-organization. They are composed of many dynamical units connected physically and functionally to each other—a complex network—and the different parts of the system are mutually adapted and produce a characteristic end state. A unique cell-specific signature emerges over time from complex interactions among constituent elements that delineate coordinate gene expression and chromosome topology. Each element itself consists of many interacting components, all dynamical in nature. Self-organizing systems can be simplified while retaining complex information using approaches that examine the relationship between elements, such as spatial relationships and transcriptional information. These relationships can be represented using well-defined networks. We hypothesize that during the process of differentiation, networks within the cell nucleus rewire according to simple rules, from which a higher level of order emerges. Studying the interaction within and among networks provides a useful framework for investigating the complex organization and dynamic function of the nucleus. PMID:20664641

  16. Charge form factor and sum rules of electromagnetic response functions in $^{12}$C

    SciTech Connect

    Lovato, Alessandro; Gandolfi, Stefano; Carlson, Joseph A.; Butler, Ralph; Lusk, Ewing; Pieper, Steven C.; Schiavilla, Rocco

    2013-08-01

    An {\\it ab initio} calculation of the $^{12}$C elastic form factor, and sum rules of longitudinal and transverse response functions measured in inclusive (e,e') scattering, is reported, based on realistic nuclear potentials and electromagnetic currents. The longitudinal elastic form factor and sum rule are found to be in satisfactory agreement with available experimental data. A direct comparison between theory and experiment is difficult for the transverse sum rule. However, it is shown that the calculated one has large contributions from two-body currents, indicating that these mechanisms lead to a significant enhancement of the quasi-elastic transverse response. This fact may have implications for the anomaly observed in recent neutrino quasi-elastic charge-changing scattering data off $^{12}$C.

  17. Novel Polycarbo-Substituted Imidazo[1,2-c]quinazolines: Synthesis and Cytotoxicity Study.

    PubMed

    Khoza, Tebogo Ankie; Makhafola, Tshepiso Jan; Mphahlele, Malose Jack

    2015-01-01

    Amination of the 2-aryl-6-bromo-4-chloro-8-iodoquinazolines with 2-aminoethanol followed by acid-promoted cyclodehydration of the incipient 2-((6,8-dihalo-2-phenylquinazolin-4-yl)amino)ethanols afforded the corresponding novel 5-aryl-9-bromo-7-iodo-2,3-dihydro-2H-imidazo[1,2-c]quinazolines. The latter were, in turn, subjected to sequential (Sonogashira and Suzuki-Miyaura) and one-pot two-step (Sonogashira/Stille) cross-coupling reactions to afford diversely functionalized polycarbo-substituted 2H-imidazo[1,2-c]quinazolines. The imidazoquinazolines were screened for in vitro cytotoxicity against human breast adenocarcinoma (MCF-7) cells and human cervical cancer (HeLa) cells. PMID:26694336

  18. Analysis of the 11B(d,n)12C Reaction

    NASA Astrophysics Data System (ADS)

    Ridling, Nathan; Prior, Richard; Spraker, Mark; Weller, Henry; Perdue, Brent

    2006-10-01

    Studies have been performed on the ^11B(d,n)^12C reaction to measure the absolute astrophysical S factor and its energy dependence, the reaction cross section, and tensor and vector analyzing powers T20, T21, T22, and iT11. The motivation behind this research project is not only its relevance to nuclear astrophysics, but also in the reaction dynamics of (d,n) reactions at very low energies. PSD (Pulse shape discrimination) was used along with PAW (Physics Analysis Workstation) in order to extract the neutrons from the gamma-rays. Using a neutron response function fitting routine in Root, we have determined the number of neutron counts leading to the ground and first excited states of ^12C. These yields were used to construct the angular distributions of the cross section and analyzing powers. Ultimately, we will extract the reaction specific transition matrix elements.

  19. Nucleosynthesis in the Hyades Open Cluster: Evidence for the Enhanced Depletion of 12C

    NASA Astrophysics Data System (ADS)

    Schuler, Simon C.; King, Jeremy R.; The, Lih-Sin

    2010-03-01

    We present the results of a light element abundance analysis of three solar-type main sequence (MS) dwarfs and three red giant branch (RGB) clump stars in the Hyades open cluster using high-resolution and high signal-to-noise spectroscopy. The CNO abundances of each group (MS or RGB) are in excellent star-to-star agreement and confirm that the giants have undergone first dredge-up mixing. The observed abundances are compared to predictions of a standard stellar model based on the Clemson-American University of Beirut (CAUB) stellar evolution code. The model reproduces the observed evolution of the N and O abundances, as well as the previously derived 12C/13C ratio, but it fails to predict the observed level of 12C depletion in the giants. More tellingly, the sum of the observed giant CNO abundances does not equal that of the dwarfs.

  20. Projectile and Target Fragmentation in the Interaction of 12C and 27Al

    SciTech Connect

    Foertsch, S.V.; Steyn, G.F.; Lawrie, J.J.; Smit, F.D.; Cerutti, F.; Colleoni, P.; Gadioli, E.; Mairani, A.; Connell, S.H.; Fearick, R.W.; Thovhogi, T.; Machner, H.; Goldenbaum, F.; Pysz, K.

    2005-05-24

    The emission of intermediate mass fragments (IMFs) produced in the inclusive 12C+27Al and 27Al+12C reactions at incident energies corresponding to a c.m. excitation energy of 107.5 MeV were studied at lab. angles of 12 deg. to 25 deg. Double differential cross sections of the IMF spectra are compared to model calculations, which include direct breakup of both the projectile and target, nucleon coalescence, as well as partial and complete fusion. This study indicates the importance of the complementary nature of a reaction together with its inverse process in fully understanding the driving reaction mechanisms in the interaction of two light-mass nuclei.

  1. The C-12/C-13 ratio in Jupiter from the Voyager infrared investigation

    NASA Technical Reports Server (NTRS)

    Courtin, R.; Gautier, D.; Marten, A.; Kunde, V.

    1983-01-01

    An analysis of the v(4) band of CH4 in the spectra recorded by the Voyager 1 IRIS experiment has yielded a C-12/C-13 ratio in Jupiter that is 160 plus 40 or minus 55, or 1.8 plus 0.4 or minus 0.6 times the terrestrial value. It is noted that while no plausible theory predicts such a difference between the C-12/C-13 ratio values of Jupiter and the inner solar system, values of this ratio in the solar neighborhood 4.5 million years ago, inferred from recent interstellar medium measurements, are compatible with the present determination in Jupiter. The Jovian, rather than the terrestrial value, would then be representative of the carbon isotope ratio in the primitive solar nebula.

  2. Electromagnetic selection rules in the triangular α-cluster model of 12C

    NASA Astrophysics Data System (ADS)

    Stellin, G.; Fortunato, L.; Vitturi, A.

    2016-08-01

    After recapitulating the procedure to find the bands and the states occurring in the {{ D }}3h alpha-cluster model of 12C in which the clusters are placed at the vertexes of an equilateral triangle, we obtain the selection rules for electromagnetic transitions. While the alpha-cluster structure leads to the cancellation of E1 transitions, the approximations carried out in deriving the rotational-vibrational Hamiltonian lead to the disappearance of M1 transitions. Furthermore, although in general the lowest active modes are E2, E3, ... and M2, M3, ..., the cancellation of M2, M3 and M5 transitions between certain bands also occur as a result of the application of group theoretical techniques drawn from molecular physics. These implications can be very relevant for the spectroscopic analysis of γ-ray spectra of 12C.

  3. Two Categories of 13C/12C Ratios for Higher Plants 1

    PubMed Central

    Smith, Bruce N.; Epstein, Samuel

    1971-01-01

    13C/12C ratios have been determined for plant tissue from 104 species representing 60 families. Higher plants fall into two categories, those with low δPDBI13C values (—24 to —34‰) and those with high δ 13C values (—6 to —19‰). Algae have δ 13C values of —12 to —23‰. Photosynthetic fractionation leading to such values is discussed. PMID:16657626

  4. Isoscalar monopole and dipole excitations of cluster states and giant resonances in 12C

    NASA Astrophysics Data System (ADS)

    Kanada-En'yo, Yoshiko

    2016-05-01

    The isoscalar monopole (ISM) and dipole (ISD) excitations in 12C are investigated theoretically with the shifted antisymmetrized molecular dynamics (AMD) plus 3 α -cluster generator coordinate method (GCM). The small-amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by a small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large-amplitude cluster modes are incorporated by superposing 3 α -cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present a calculation that describes the ISM and ISD excitations over a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, although the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster modes are enhanced by the distance motion between α clusters, and they split into a couple of states because of the angular motion of α clusters. The low-energy ISM strengths exhaust 26% of the energy-weighted sum rule, which is consistent with the experimental data for the 12C(02+; 7.65 MeV) and 12C(03+; 10.3 MeV) measured by (e ,e') ,(α ,α') , and (6Li,6Li' ) scatterings. In the calculated low-energy ISD strengths, two 1- states (the 11- and 12- states) with the significant strengths are obtained over E =10 -15 MeV. The results indicate that the ISD excitations can be a good probe to experimentally search for new cluster states such as the 12C(12-) obtained in the present calculation.

  5. Corrections to the one-photon approximation in the 0+-->2+ transition of 12C

    SciTech Connect

    Paul Gueye; Madeleine Bernheim; J. F. Danel; Jean-Eric Ducret; L. Lakehal-Ayat; Jean-Marc Le Goff; Alain Magnon; Claude Marchand; Edmond Offermann; Jacques Marroncle; Pascal Vernin; Marco C. Traini; Vincent Breton; Salvatore Frullani; Franco Garibaldi; Francesco Ghio; Mauro Iodice; Zein-Eddine Meziani

    2001-04-18

    Contribution of higher order effects to the one-photon exchange approximation were studied in the first excited state of 12C by comparing inclusive inelastic scattering cross sections of electrons and positrons obtained at the Saclay Linear Accelerator. The data were compared to a distorted wave Born approximation (DWBA)calculation. The results indicate an effect less than 2% within 2sigma, compatible with what was observed in recent elastic scattering measurements.

  6. Muon and neutrino production in inclusive proton-/sup 12/C reactions

    SciTech Connect

    Mintz, S.L.

    1987-01-01

    We present an estimate for the cross section for the inclusive reaction p+ /sup 12/C..--> mu../sup +/+..nu..+X, where X is a nuclear state. For an incident proton c.m. energy of 1076 MeV, a cross section of 4.41 x 10/sup -42/ cm/sup 2/ is obtained. The possibility of observing anomalous threshold states is also discussed.

  7. Multiple-scattering effects in nucleus-nucleus reactions with Glauber theory

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Shinya; Ebata, Shuichiro; Horiuchi, Wataru; Kimura, Masaaki

    2014-09-01

    A study of new unstable nuclei has become possible in new radioactive beam facilities. In order to understand the relationship between reaction observables and nuclear structure, we need reaction theory which exactly reflects the nuclear structure. The Glauber theory is a powerful tool of analyzing high energy nuclear reactions. The theory describes the multiple scattering processes, whereas the optical limit approximation (OLA), which is widely used, ignores those processes. Those effects are expected to play an important role in the nuclear collision involving unstable nuclei (see for example Phys. Rev. C 54, 1843 (1996)). Here we apply the Glauber theory to nucleus-nucleus reactions. The wave functions are generated by the Skyrme-Hartree-Fock method and are expressed in a Slater determinant that allows us to evaluate the complete Glauber amplitude easily. We calculate total reaction cross sections, elastic cross sections and differential elastic cross sections for 16~24O, 40~70Ca, 56,58Ni, 100~140Sn, 190~214Pb on proton, 4He, 12C targets and compare with experimental data. The Glauber theory gives much better description than the OLA, especially at larger scattering angles.

  8. Measurements and Modeling of (16)O(12)C(17)O Spectroscopic Parameters at 2µm

    NASA Astrophysics Data System (ADS)

    Jacquemart, D.; Sung, K.; Brown, L. R.; Coleman, M.; Mantz, A. W.; Smith, M. A. H.

    2014-06-01

    In the present study, line-intensity measurements for 16O12C17O were performed using a high-resolution Fourier transform spectrometer (Bruker IFS-125HR) together with a Herriott cell allowing a 20.956 m absorption path. For this, a 17O-enriched CO2 gas sample mixture was used. The 16O12C17O isotopologue abundance in the sample was determined to be 0.3991 by mass spectrometry. Since a collisional narrowing effect has been observed, the Rautian profile was systematically used instead of the Voigt profile. Finally, around 1000 transitions were studied between 4604 and 5126 cm-1 involving 15 bands of the 16O12C17O isotopologue. For each of the 15 bands, transition dipole moments and Herman-Wallis factors were derived, which also enabled a global comparison with theoretical calculations and predictions achieved for carbon dioxide. For the measured and calculated line positions, the accuracy is between 0.1 - 1×10-3 cm-1. For line intensities, depending on the intensity of the band, accuracies are between 2 - 3 % for 5 cold bands and 2 hot bands and between 6 - 30 % for 8 weaker hot bands. Results from this work are compared to previous works and to HITRAN 2012. Complete line lists were generated to support atmospheric remote sensing for the Earth (e.g. GOSAT, OCO-2 ...), Mars and Venus.

  9. C-12/C-13 Ratio in Ethane on Titan and Implications for Methane's Replenishment

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Romani, Paul N.; Bjoraker, Gordon L.; Sada, Pedro V.; Nixon, Conor A.; Lunsford, Allen W.; Boyle, Robert J.; Hesman, Brigette E.; McCabe, George H.

    2009-01-01

    The C-12/C-13 abundance ratio in ethane in the atmosphere of Titan has been measured at 822 cm(sup -1) from high spectral resolution ground-based observations. The value 89(8), coincides with the telluric standard and also agrees with the ratio seen in the outer planets. It is almost identical to the result for ethane on Titan found by the composite infrared spectrometer (CIRS) on Cassini. The C-12/C-13 ratio for ethane is higher than the ratio measured in atmospheric methane by Cassini/Huygens GCMS, 82.3(l), representing an enrichment of C-12 in the ethane that might be explained by a kinetic isotope effect of approximately 1.1 in the formation of methyl radicals. If methane is being continuously resupplied to balance photochemical destruction, then we expect the isotopic composition in the ethane product to equilibrate at close to the same C-12/C-13 ratio as that in the supply. The telluric value of the ratio in ethane then implies that the methane reservoir is primordial.

  10. Electric quadrupole excitations in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1989-01-01

    Calculations are presented for electric quadrupole excitations in relativistic nucleus-nucleus collisions. The theoretical results are compared to an extensive data set and it is found that electric quadrupole effects provide substantial corrections to cross sections, especially for heavier nuclei.

  11. Meson multiplicity versus energy in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Atwater, T. W.; Freier, P. S.

    1986-01-01

    A systematic study of meson multiplicity as a function of energy at energies up to 100 GeV/u in nucleus-nucleus collisions has been made, using cosmic-ray data in nuclear emulsion. The data are consistent with simple nucleon-nucleon superposition models. Multiplicity per interacting nucleon in AA collisions does not appear to differ significantly from pp collisions.

  12. Scaling phenomenon in relativistic nucleus-nucleus collisions

    SciTech Connect

    Wong, C. Y.; Blankenbecler, R.

    1980-01-01

    New scaling variables for proton and pion production in relativistic nucleus-nucleus collisions are introduced which are the generalizations of the Feynmann scaling variable. They allow a simple description of the cross sections at forward and backward angles. 2 figures.

  13. Momentum loss in proton-nucleus and nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Khan, Ferdous; Townsend, Lawrence W.

    1993-01-01

    An optical model description, based on multiple scattering theory, of longitudinal momentum loss in proton-nucleus and nucleus-nucleus collisions is presented. The crucial role of the imaginary component of the nucleon-nucleon transition matrix in accounting for longitudinal momentum transfer is demonstrated. Results obtained with this model are compared with Intranuclear Cascade (INC) calculations, as well as with predictions from Vlasov-Uehling-Uhlenbeck (VUU) and quantum molecular dynamics (QMD) simulations. Comparisons are also made with experimental data where available. These indicate that the present model is adequate to account for longitudinal momentum transfer in both proton-nucleus and nucleus-nucleus collisions over a wide range of energies.

  14. The Galactic Nucleus

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio

    Exciting new broadband observations of the galactic nucleus have placed the heart of the Milky Way under intense scrutiny in recent years. This has been due in part to the growing interest from theorists motivated to study the physics of black hole accretion, magnetized gas dynamics, and unusual star formation. The center of our Galaxy is now known to harbor the most compelling supermassive black hole candidate, weighing in at 3-4 million solar masses. Its nearby environment is comprised of a molecular dusty ring, clusters of evolved and young stars, diffuse hot gas, ionized gas streamers, and several supernova remnants. This chapter will focus on the physical makeup of this dynamic region and the feasibility of actually imaging the black hole's shadow in the coming decade with mm interferometry.

  15. Neutrino-Nucleus Reactions and Nucleosynthesis

    SciTech Connect

    Suzuki, Toshio; Chiba, Satoshi; Yoshida, Takashi; Honma, Michio; Higashiyama, Koji; Umeda, Hideyuki; Nomoto, Ken'ichi; Kajino, Toshitaka; Otsuka, Takaharu

    2008-05-21

    Neutrino-induced reactions on {sup 12}C, {sup 4}He as well as Fe and Ni isotopes are studied based on new shell model Hamiltonians for p-shell and fp-shell. Gamow-Teller and spin-dipole transitions are investigated, and applied to neutrino-nucleus reactions induced by both DAR and supernova neutrinos. The reaction cross sections are found to be enhanced compared with conventional Hamiltonians as well as previous calculations. The production yields of {sup 7}Li and {sup 11}B during supernova explosions are found to be enhanced, and the effects of neutrino oscillations and implications of the enhancement on the constraint on temperature for {nu}{sub {mu}}{sub ,{tau}} and {nu}-bar{sub {mu}}{sub ,{tau}} are discussed. Production of other light elements such as {sup 10}Be and {sup 10}B by neutrino processes is also discussed. Neutral current reactions on Ni and Fe isotopes induced by supernova neutrinos are investigated. Effects of neutrino-induced reactions on the production yields of heavy elements such as Mn are discussed.

  16. Experimental Energy Levels and Partition Function of the 12C2 Molecule

    NASA Astrophysics Data System (ADS)

    Furtenbacher, Tibor; Szabó, István; Császár, Attila G.; Bernath, Peter F.; Yurchenko, Sergei N.; Tennyson, Jonathan

    2016-06-01

    The carbon dimer, the 12C2 molecule, is ubiquitous in astronomical environments. Experimental-quality rovibronic energy levels are reported for 12C2, based on rovibronic transitions measured for and among its singlet, triplet, and quintet electronic states, reported in 42 publications. The determination utilizes the Measured Active Rotational-Vibrational Energy Levels (MARVEL) technique. The 23,343 transitions measured experimentally and validated within this study determine 5699 rovibronic energy levels, 1325, 4309, and 65 levels for the singlet, triplet, and quintet states investigated, respectively. The MARVEL analysis provides rovibronic energies for six singlet, six triplet, and two quintet electronic states. For example, the lowest measurable energy level of the {{a}}{}3{{{\\Pi }}}{{u}} state, corresponding to the J = 2 total angular momentum quantum number and the F 1 spin-multiplet component, is 603.817(5) cm‑1. This well-determined energy difference should facilitate observations of singlet–triplet intercombination lines, which are thought to occur in the interstellar medium and comets. The large number of highly accurate and clearly labeled transitions that can be derived by combining MARVEL energy levels with computed temperature-dependent intensities should help a number of astrophysical observations as well as corresponding laboratory measurements. The experimental rovibronic energy levels, augmented, where needed, with ab initio variational ones based on empirically adjusted and spin–orbit coupled potential energy curves obtained using the Duo code, are used to obtain a highly accurate partition function, and related thermodynamic data, for 12C2 up to 4000 K.

  17. Neutral weak-current two-body contributions in inclusive scattering from {sup 12}C

    SciTech Connect

    Lovato, Alessandro; Gandolfi, Stefano; Carlson, Joseph; Pieper, S. C.; Schiavilla, Rocco

    2014-05-01

    An {\\it ab initio} calculation of the sum rules of the neutral weak response functions in $^{12}$C is reported, based on a realistic Hamiltonian, including two- and three-nucleon potentials, and on realistic currents, consisting of one- and two-body terms. We find that the sum rules of the response functions associated with the longitudinal and transverse components of the (space-like) neutral current are largest and that a significant portion ($\\simeq 30$\\%) of the calculated strength is due to two-body terms. This fact may have implications for the MiniBooNE and other neutrino quasi-elastic scattering data on nuclei.

  18. C12/C13-ratio determination in nanodiamonds by atom-probe tomography.

    PubMed

    Lewis, Josiah B; Isheim, Dieter; Floss, Christine; Seidman, David N

    2015-12-01

    The astrophysical origins of ∼ 3 nm-diameter meteoritic nanodiamonds can be inferred from the ratio of C12/C13. It is essential to achieve high spatial and mass resolving power and minimize all sources of signal loss in order to obtain statistically significant measurements. We conducted atom-probe tomography on meteoritic nanodiamonds embedded between layers of Pt. We describe sample preparation, atom-probe tomography analysis, 3D reconstruction, and bias correction. We present new data from meteoritic nanodiamonds and terrestrial standards and discuss methods to correct isotopic measurements made with the atom-probe tomograph. PMID:26095824

  19. Antiproton-nucleus interaction

    NASA Astrophysics Data System (ADS)

    Cugnon, J.; Vandermeulen, J.

    The antiproton-nucleus physics is reviewed. On the experimental side, the recent results obtained at the LEAR, BNL and KEK facilities are analyzed. A brief summary of the main pp and pn experimental data is also given. The antiproton-nucleus interaction can lead to elasic, inelastic and charge exchange scattering and to annihilation. The latter is very dominant. The scattering cross-sections are usually analyzed in terms of complex potential models. The relationship between potentials, charge conjugation and Dirac phenomenology is discussed. Much emphasis is put on the dynamics of the antiproton annihilation on nuclei. The energy transfer, pion absorption and target response are analyzed within the intranuclear cascade model. Special interest is devoted to strangeness production, hypernucleus formation and possible annihilation on two nucleons. Signatures for this new process are searched in experimental data. Finally, the highly debated question of quark-gluon formation is analyzed. Cet article constitue une revue de la physique antiproton-noyau. Du point de vue expérimental, cette revue porte particulièrement sur les récents résultats obtenus à LEAR, BNL et KEK. On y a aussi inclus une mise à jour des faits expérimentaux principaux pour pp et pn. L'interaction antiproton-noyau conduit à la diffusion élastique, inélastique et d'xA9change de charge et à des processus d'annihilation. Habituellement, les expériences de diffusion sont analysées en termes de potentiels complexes. La relation entre ces potentiels, la conjugaison de charge et la phénoménologie de Dirac est discutée. On s'est particulièrement intéressé à la dynamique de l'annihilation d'antiprotons sur des noyaux. Le transfert d'énergie, l'absorption de pions et la réponse de la cible sont analysés dans le cadre du modèle de cascade intranucléaire. Certains autres points sont discutés plus en détail: la production d'étrangeté, la formation d'hypernoyaux et l'annihilation sur

  20. Mechanics of the Nucleus

    PubMed Central

    Lammerding, Jan

    2015-01-01

    The nucleus is the distinguishing feature of eukaryotic cells. Until recently, it was often considered simply as a unique compartment containing the genetic information of the cell and associated machinery, without much attention to its structure and mechanical properties. This article provides compelling examples that illustrate how specific nuclear structures are associated with important cellular functions, and how defects in nuclear mechanics can cause a multitude of human diseases. During differentiation, embryonic stem cells modify their nuclear envelope composition and chromatin structure, resulting in stiffer nuclei that reflect decreased transcriptional plasticity. In contrast, neutrophils have evolved characteristic lobulated nuclei that increase their physical plasticity, enabling passage through narrow tissue spaces in their response to inflammation. Research on diverse cell types further demonstrates how induced nuclear deformations during cellular compression or stretch can modulate cellular function. Pathological examples of disturbed nuclear mechanics include the many diseases caused by mutations in the nuclear envelope proteins lamin A/C and associated proteins, as well as cancer cells that are often characterized by abnormal nuclear morphology. In this article, we will focus on determining the functional relationship between nuclear mechanics and cellular (dys-)function, describing the molecular changes associated with physiological and pathological examples, the resulting defects in nuclear mechanics, and the effects on cellular function. New insights into the close relationship between nuclear mechanics and cellular organization and function will yield a better understanding of normal biology and will offer new clues into therapeutic approaches to the various diseases associated with defective nuclear mechanics. PMID:23737203

  1. Measurements of 12 C ion fragmentation on thin carbon target from the FIRST collaboration at GSI

    NASA Astrophysics Data System (ADS)

    Toppi, M.; FIRST Collaboration

    2015-04-01

    The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI laboratory took data in summer 2011, studying the collisions of a 12C ion beam with Carbon and Au thin targets. The experiment main purpose is the double differential cross section measurement of the carbon ion fragmentation at energies that are relevant both for tumor therapy and space radiation protection applications (100-1000 MeV/u). The FIRST dataset contains carbon ions collisions on a 3.43 g·Cin-2 carbon target (about 24 M events) and on a 0.96 g·cm-2 Au target (about 4.5 M events). The SIS (heavy ion synchrotron) was used to accelerate the 12C ions at the energy of 400 MeV/u. The preliminary results of differential cross sections measurements as a function of angle and energy for carbon target, in the small angle region (θ ≤ 5°), are presented.

  2. The anharmonic resonances in the infrared spectrum of 12 C 13 CH 2

    NASA Astrophysics Data System (ADS)

    Fusina, L.; Bramati, G.; Mazzavillani, A.; di Lonardo, G.

    The vibration-rotation spectrum of 13 C mono-substituted acetylene, 12 C 13 CH 2 , has been recorded in the region between 1100 and 3500 cm -1 at instrumental (4 ×10 -3} cm -1 ) or Doppler limited (6- 8 ×10 -3 cm -1 ) resolution. Hot and cold bands involving the stretchings ν1 , ν2 and ν3 and the stretching-bending combination bands with v 2 = 1, v 4 ≤1 and v 5 ≤2 have been observed and analysed. The anharmonic resonances within the dyads ν 1 / ( ν2 +2 ν 5 ) and ν 3 / ( ν2 + ν 4 + ν5 ), which strongly perturb the spectrum of 13 C 2 H 2 and 12 C 2 H 2 , respectively, have been analysed. From the simultaneous treatment of all the assigned transitions a set of deperturbed molecular parameters, containing also the coupling coefficients K 1,255 and K 3,245 , was derived. They fully characterize the ro-vibrational pattern of the observed stretching and stretching-bending combination states and provide an accurate description of the anharmonic resonances in the molecule.

  3. Efficiency Calibration for Measuring the 12C(n, 2n)11C Cross Section

    NASA Astrophysics Data System (ADS)

    Eckert, Thomas; Gula, August; Vincett, Laurel; Yuly, Mark; Padalino, Stephen; Russ, Megan; Bienstock, Mollie; Simone, Angela; Ellison, Drew; Desmitt, Holly; Sangster, Craig; Regan, Sean; Fitzgerald, Ryan

    2015-11-01

    One possible inertial confinement fusion diagnostic involves tertiary neutron activation via the 12C(n, 2n)11C reaction. A recent experiment to measure this reaction cross-section involved coincidence counting the annihilation gamma rays produced by the positron decay of 11C. This requires an accurate value for the full-peak coincidence efficiency of the NaI detector system. The GEANT 4 toolkit was used to develop a Monte Carlo simulation of the detector system which can be used to calculate the required efficiencies. For validation, simulation predictions have been compared with the results of two experiments. In the first, full-peak coincidence positron annihilation efficiencies were measured for 22Na decay positrons that annihilate in a small plastic scintillator. In the second, a NIST-calibrated 68Ge source was used. A comparison of calculated with measured efficiencies, as well as 12C(n, 2n)11C cross sections are presented. Funded in part by a grant from the DOE through the Laboratory for Laser Energetics.

  4. Vibrational dynamics of a non-degenerate ultrafast rotor: The (C12,C13)-oxalate ion

    PubMed Central

    Kuroda, Daniel G.; Abdo, Mohannad; Chuntonov, Lev; Smith, Amos B.; Hochstrasser, Robin M.

    2013-01-01

    Molecular ions undergoing ultrafast conformational changes on the same time scale of water motions are of significant importance in condensed phase dynamics. However, the characterization of systems with fast molecular motions has proven to be both experimentally and theoretically challenging. Here, we report the vibrational dynamics of the non-degenerate (C12,C13)-oxalate anion, an ultrafast rotor, in aqueous solution. The infrared absorption spectrum of the (C12,C13)-oxalate ion in solution reveals two vibrational transitions separated by approximately 40 cm−1 in the 1500–1600 cm−1 region. These two transitions are assigned to vibrational modes mainly localized in each of the carboxylate asymmetric stretch of the ion. Two-dimensional infrared spectra reveal the presence and growth of cross-peaks between these two transitions which are indicative of coupling and population transfer, respectively. A characteristic time of sub-picosecond cross-peaks growth is observed. Ultrafast pump-probe anisotropy studies reveal essentially the same characteristic time for the dipole reorientation. All the experimental data are well modeled in terms of a system undergoing ultrafast population transfer between localized states. Comparison of the experimental observations with simulations reveal a reasonable agreement, although a mechanism including only the fluctuations of the coupling caused by the changes in the dihedral angle of the rotor, is not sufficient to explain the observed ultrafast population transfer. PMID:24182056

  5. Measurement of the fusion excitation function for 19O + 12C at near barrier energies

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Steinbach, T. K.; Vadas, J.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Tripathi, V.; Kuvin, S. A.; Wiedenhover, I.

    2015-10-01

    Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for 18O and 19O nuclei incident on a 12C target. A beam of 19O was produced by the 18O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting 19O beam bombarded a 100 μg/cm2 12C target at an intensity of 2-4 × 103 p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Using silicon detectors, micro-channel plate detectors, and an ionization chamber, evaporation residues were detected in the angular range θlab <= 23° with high efficiency. Initial experimental results including measurement of the fusion cross-section to approximately the 100 mb level will be presented. The measured excitation function will be compared to theoretical predictions. Supported by the US DOE under Grand No. DEFG02-88ER-40404.

  6. Direct measurement of 11B(p ,γ )12C astrophysical S factors at low energies

    NASA Astrophysics Data System (ADS)

    He, J. J.; Jia, B. L.; Xu, S. W.; Chen, S. Z.; Ma, S. B.; Hou, S. Q.; Hu, J.; Zhang, L. Y.; Yu, X. Q.

    2016-05-01

    We directly measure the absolute cross section of 11B(p ,γ )12C in the energy region of Ec .m .=130 -257 keV by using a thin target for the first time. This work is performed on a 320-kV platform at the Institute of Modern Physics in Lanzhou. The astrophysical S factors of this reaction are obtained for capture to the ground and first excited states of 12C. The properties of the known resonance at ˜150 keV are derived and agree with the previous results. However, in the energy region of 170-240 keV, our S factors are about 15%-50% larger than the adopted values in NACRE II and are also larger than the upper limits of NACRE II by up to ˜20 % . This indicates that our new reaction rate is enhanced by about 15%-50% compared to the NACRE II adopted rate in the temperature region 0.32-0.62 GK.

  7. Theoretical investigation of stabilities and optical properties of Si12C12 clusters.

    PubMed

    Duan, Xiaofeng F; Burggraf, Larry W

    2015-01-21

    By sorting through hundreds of globally stable Si12C12 isomers using a potential surface search and using simulated annealing, we have identified low-energy structures. Unlike isomers knit together by Si-C bonds, the lowest energy isomers have segregated carbon and silicon regions that maximize stronger C-C bonding. Positing that charge separation between the carbon and silicon regions would produce interesting optical absorption in these cluster molecules, we used time-dependent density functional theory to compare the calculated optical properties of four isomers representing structural classes having different types of silicon and carbon segregation regions. Absorptions involving charge transfer between segregated carbon and silicon regions produce lower excitation energies than do structures having alternating Si-C bonding for which frontier orbital charge transfer is exclusively from separated carbon atoms to silicon atoms. The most stable Si12C12 isomer at temperatures below 1100 K is unique as regards its high symmetry and large optical oscillator strength in the visible blue. Its high-energy and low-energy visible transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer. PMID:25612705

  8. Applying new tools to old problems—experimental studies of resonances in 12C

    NASA Astrophysics Data System (ADS)

    Kirsebom, O. S.; Fynbo, H. O. U.; Howard, A. M.; Laursen, K. L.

    2014-12-01

    We report preliminary results from an experimental study of the p + 11B reaction at beam energies of 2.00 MeV, 2.63 MeV and 3.12 MeV, corresponding to three known 0+, 2+ and 3- resonances in 12C at excitation energies of 17.79 MeV, 18.38 MeV and 18.81 MeV. The resonances have small γ-decay branches to lower-lying resonances of the order of 10-6- 10-5. By detecting the three outgoing a particles in coincidence and measuring their momenta, we obtain complete kinematics information. From the combined energy of the α particles we determine the energy of the γ transition. In this way, we identify two previously observed transitions, (0+, 17.79) → (1+, 12.71) and (3-, 18.38) → (3- 9.64), and one new transition, (2+, 18.81) → (1+, 12.71). The results demonstrate the usefulness of γ decay as a probe of the low-lying resonance spectrum of 12C in the search for new broad (cluster) resonances.

  9. Global optical potential for nucleus-nucleus systems from 50 MeV/u to 400 MeV/u

    NASA Astrophysics Data System (ADS)

    Furumoto, T.; Horiuchi, W.; Takashina, M.; Yamamoto, Y.; Sakuragi, Y.

    2012-04-01

    We present a new global optical potential (GOP) for nucleus-nucleus systems, including neutron-rich and proton-rich isotopes, in the energy range of 50-400 MeV/u. The GOP is derived from the microscopic folding model with the complex G-matrix interaction CEG07 and the global density presented by the São Paulo group. The folding model accounts for realistic complex optical potentials of nucleus-nucleus systems well and reproduces the existing elastic scattering data for stable heavy-ion projectiles at incident energies above 50 MeV/u. We then calculate the folding-model potentials (FMPs) for projectiles of even-even isotopes, 8-22C, 12-24O, 16-38Ne, 20-40Mg, 22-48Si, 26-52S, 30-62Ar, and 34-70Ca, scattered by stable target nuclei of 12C, 16O, 28Si, 40Ca 58Ni, 90Zr, 120Sn, and 208Pb at incident energies of 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 250, 300, 350, and 400 MeV/u. The calculated FMP is represented, with a sufficient accuracy, by a linear combination of 10-range Gaussian functions. The expansion coefficients depend on the incident energy, the projectile and target mass numbers, and the projectile atomic number, while the range parameters depend only on the projectile and target mass numbers. The adequate mass region of the present GOP by the global density is inspected in comparison with FMP by realistic density. The full set of the range parameters and the coefficients for all the projectile-target combinations at each incident energy are provided on a permanent open-access website together with a fortran program for calculating the microscopic-basis GOP (MGOP) for a desired projectile nucleus by the spline interpolation over the incident energy and the target mass number.

  10. Two Neutron Removal in Relativistic Nucleus-Nucleus Reactions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Significant discrepancies between theory and experiment have previously been noted for double neutron removal via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work examines the cause of these discrepancies and systematically investigates whether the problem might be due to electromagnetic theory, nuclear contributions, or an underestimate of experimental error. Using cross section systematics from other reactions it is found that the discrepancies can be resolved in a plausible manner.

  11. Examining the Structure of the Oxygen-16 Nucleus

    NASA Astrophysics Data System (ADS)

    Sauer, Ethan; Aprahamian, Ani; Tan, Wanpeng; Gyurjinyan, Armen; Frentz, Bryce; Guerin, Benjamin

    2015-10-01

    The intent of this work is to explore the structure of the nucleus of Oxygen-16 (16O), which consists of four alpha particles, each with two protons and two neutrons. 16O is generated via the fusion of helium and carbon during stellar nucleosynthesis. This reaction is crucial to the existence of life. By measuring the structure of the 16O nucleus, we hope to gain a better understanding of stellar evolution and processes. The theoretical state of most interest is a linear arrangement of the four alpha particles, proposed by Chevallier et al. in their 1967 paper to explain the surprisingly large moment of inertia of the nucleus they measured. The existence of this state can be most accurately observed through an analysis of the energy spectra of the decay products. This method has previously been implemented at Notre Dame by Freer et al. when a similar structure, that of Carbon-12 (12C), was analyzed, and a previously unknown state was observed. The data gathered is analyzed using the method of angular correlation, which makes use of the angles and energies of decay products relative to the center of mass frame to reconstruct possible spins of the initial state. Analysis is currently underway and results will be presented at CEU 2015. Supported by NSF Grant PHY-1419765.

  12. Unexpected doubly-magic nucleus.

    SciTech Connect

    Janssens, R. V. F.; Physics

    2009-01-01

    Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope {sup 24}O has been found to be one such nucleus - yet it lies just at the limit of stability.

  13. Spectral temperatures of {Delta}{sup 0}(1232) resonances produced in p{sup 12}C and d{sup 12}C collisions at 4.2 GeV/c per nucleon

    SciTech Connect

    Khan, Imran; Olimov, Kh. K.

    2013-07-15

    The reconstructed experimental transverse momentum (p{sub t}) distributions of {Delta}{sup 0}(1232) resonances produced in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c and the corresponding spectra calculated using Modified FRITIOF model were analyzed in the framework of Hagedorn Thermodynamic Model. The spectral temperatures of {Delta}{sup 0}(1232) resonances were extracted from fitting their p{sub t} spectra with one-temperature Hagedorn function. The extracted spectral temperatures of {Delta}{sup 0}(1232) were compared with the corresponding temperatures of {pi}{sup -} mesons in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c obtained similarly from fitting the p{sub t} spectra of {pi}{sup -} by one-temperature Hagedorn function. The spectral temperatures of {Delta}{sup 0}(1232) resonances agreed within uncertainties with the corresponding temperatures of {pi}{sup -} mesons produced in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c.

  14. Experimental study of the 12C ( K -stopped , π0 ) 12 Λ B reaction

    NASA Astrophysics Data System (ADS)

    Ahmed, M. W.; Cui, X.; Empl, A.; Hungerford, E. V.; Lan, K. J.; Youn, M.; Chrien, R. E.; Gill, R.; Pile, P.; Rusek, A.; Sutter, R.; Bjoraker, J.; Dehnhard, D.; O'Donnell, J. M.; Gerald, J.; Juengst, H.; Liu, J. H.; Peng, J. C.; Morris, C. L.; Riedel, C. M.; Thiessen, H. A.; Androic, D.; Bertovic, I.; Furic, M.; Petkovic, T.; Planinic, M.; Tang, L.; Zeps, V.

    2003-12-01

    The ( K -stopped , π0 ) strangeness and charge changing reaction was investigated by producing a 12 Λ B hypernucleus from a carbon target. The branching ratio for K- capture to the ground and p -shell states of this hypernucleus was found to be (0.28±0.08)× 10-3 and (0.35±0.09)× 10-3 , respectively, which after correction for isospin was lower than a previously measured value for the 12 C ( K -stopped , π- ) 12ΛC reaction, but still above the theoretical predictions for the ground state. The experiment obtained a missing-mass resolution comparable to in-flight reactions, however the higher background and lower selectivity of the K -stopped reaction limits its usefulness in the study of new hypernuclear species.

  15. Proportional Counter Calibration and Analysis for 12C + p Resonance Scattering

    NASA Astrophysics Data System (ADS)

    Nelson, Austin; Rogachev, Grigory; Uberseder, Ethan; Hooker, Josh; Koshchiy, Yevgen

    2014-09-01

    Light exotic nuclei provide a unique opportunity to test the predictions of modern ab initio theoretical calculations near the drip line. In ab initio approaches, nuclear structure is described starting from bare nucleon-nucleon and three-nucleon interactions. Calculations are very heavy and can only be performed for the lightest nuclei (A < 16). Experimental information on the structure of light exotic nuclei is crucial to determine the validity of these calculations and to fix the parameters for the three-nucleon forces. Resonance scattering with rare isotope beams is a very effective tool to study spectroscopy of nuclei near the drip line. A new setup was developed at the Cyclotron Institute for effective resonance scattering measurements. The setup includes ionization chamber, silicon array, and an array of proportional counters. The proportional counter array, consisting of 8 anode wires arranged in a parallel cellular grid, is used for particle identification and to track the positioning of light recoils. The main objective of this project was to test the performance and perform position calibration of this proportional counter array. The test was done using 12C beam. The excitation function for 12C + p elastic scattering was measured and calibration of the proportional counter was performed using known resonances in 13N. The method of calibration, including solid angle calculations, normalization corrections, and position calibration will be presented. Light exotic nuclei provide a unique opportunity to test the predictions of modern ab initio theoretical calculations near the drip line. In ab initio approaches, nuclear structure is described starting from bare nucleon-nucleon and three-nucleon interactions. Calculations are very heavy and can only be performed for the lightest nuclei (A < 16). Experimental information on the structure of light exotic nuclei is crucial to determine the validity of these calculations and to fix the parameters for the three

  16. Photosynthesis and sup 13 C/ sup 12 C ratios in Amazonian rain forests

    SciTech Connect

    Van Der Merwe, N.J. ); Medina, E. )

    1989-05-01

    Measurements are reported of {sup 13}C/{sup 12}C ratios for air CO{sub 2} at different heights in two Amazonian rain forests. CO{sub 2} emitted from the forest floor is severely depleted in {sup 13}C which produces isotopically light source air throughout the forest. Air {delta}{sup 13}C values vary very little with height above ground, but are about 5 to 6{per thousand} more negative than the open atmosphere. CO{sub 2} recycling under the canopy depletes all leaf {delta}{sup 13}C values by a like amount. Additional factors further deplete leaf {delta}{sup 13}C values by 4 to 5{per thousand} at ground level; this effect decreases with height to zero in the upper canopy, yielding a gradient in {delta}{sup 13}C values.

  17. E0 strength in /sup 12/C from /sup 6/Li scattering

    SciTech Connect

    Eyrich, W.; Hofmann, A.; Lehmann, A.; Muehldorfer, B.; Schloesser, H.; Wirth, H.; Gils, H.J.; Rebel, H.; Zagromski, S.

    1987-07-01

    The (/sup 6/Li,/sup 6/Li') reaction was studied on /sup 12/C at E/sub Li/ = 156 MeV at extreme forward angles including theta = 0/sup 0/. Spectra were taken in the excitation energy region E/sub x/approx. <30 MeV. E0 strength was deduced at E/sub x/ = 7.65 MeV (9.5% energy weighted sum rule) around E/sub x/ = 10.2 MeV (5% +- 1% energy weighted sum rule) and in the region 19 MeVless than or equal toE/sub x/less than or equal to21.5 MeV (5% +- 2% energy weighted sum rule).

  18. Animal /sup 13/C//sup 12/C correlates with trophic level in pelagic food webs

    SciTech Connect

    Rau, G.H.; Mearns, A.J.; Young, D.R.; Olson, R.J.; Schafer, H.A.; Kaplan, I.R.

    1983-01-01

    Whatever the underlying cause(s), our observations further substantiate the existence of small but progressive increases in animal tissue /sup 13/C//sup 12/C with increasing trophic level. Such a relationship has significant implications for the use of stable carbon isotope natural abundance in animal tissues or remains, in order to interpret the tropic structure and food base of past as well as present-day animal communities. The delta/sup 13/C of the marine animal tissues analyzed ranged from -20.6 to -15.8%. The macro-fauna from the eastern tropical Pacific Ocean had higher isotope values than the net plankton collected from the same area. The average increases in delta/sup 13/C per trophic level were 0.73 and 1.38% for the California coastal waters and for the eastern tropical Pacific, respectively. These isotopic increases approximate closely those previously reported to occur within single trophic level steps.

  19. Enhancement of radioactivity of /sup 14/C-/sup 12/C mixtures via partial reduction

    SciTech Connect

    Stevenson, G.R.; Lauricella, T.L.

    1986-08-20

    The solution electron affinities of perdeuterated polyaromatics are less than those of the protiated materials. This observation prompted the investigation of the possibility of increasing the radioactivity of benzophenone-carbonyl-/sup 14/C (BZO-14C)-cold benzophenone (BZO-12C) mixtures via the partial reduction of these mixtures to the ketyls. The /sup 14/C-depleted benzophenones left in the reaction vessel in the form of Na/sup +/(NH/sub 3/)BZO/sup -/ can be recovered by simply adding a solution of I/sub 2/ in tetrahydrofuran to the solid salt. Further, there is no theoretical limit as to how much the radioactivity of the sample can be enhanced by passing /sup 14/C-enhanced material through this process consecutively, up to the point where the pure carbon-14 compound is obtained.

  20. Elastic constant C11 of 12C diamond between 10 and 613 K

    NASA Astrophysics Data System (ADS)

    Nagakubo, A.; Arita, M.; Ogi, H.; Sumiya, H.; Nakamura, N.; Hirao, M.

    2016-05-01

    We measured the temperature dependence of the elastic constant C11 of a 12C diamond monocrystal using picosecond ultrasonics between 10 and 613 K. We found that C11 is almost temperature independent below room temperature; the temperature coefficient around 300 K is -6.6 MPa/K. Our results show a significantly higher Einstein temperature than reported values by ˜30%, indicating that diamond has a larger zero-point energy, which remains dominant around ambient temperature. We also calculated the temperature dependence of the elastic constants using ab-initio methods, resulting in good agreement with measurements. Our study shows that below-ambient-temperature measurements are not sufficient to extract the Debye temperature and the Grüneisen parameter of high-Debye-temperature materials.

  1. 12C+p resonant elastic scattering in the Maya active target

    NASA Astrophysics Data System (ADS)

    Sambi, S.; Raabe, R.; Borge, M. J. G.; Caamano, M.; Damoy, S.; Fernández-Domínguez, B.; Flavigny, F.; Fynbo, H.; Gibelin, J.; Grinyer, G. F.; Heinz, A.; Jonson, B.; Khodery, M.; Nilsson, T.; Orlandi, R.; Pancin, J.; Perez-Loureiro, D.; Randisi, G.; Ribeiro, G.; Roger, T.; Suzuki, D.; Tengblad, O.; Thies, R.; Datta, U.

    2015-03-01

    In a proof-of-principle measurement, the Maya active target detector was employed for a 12C( p, p) resonant elastic scattering experiment in inverse kinematics. The excitation energy region from 0 to 3MeV above the proton breakup threshold in 13N was investigated in a single measurement. By using the capability of the detector to localize the reaction vertex and record the tracks of the recoiling protons, data covering a large solid angle could be utilized, at the same time keeping an energy resolution comparable with that of direct-kinematics measurements. The excitation spectrum in 13N was fitted using the R-matrix formalism. The level parameters extracted are in good agreement with previous studies. The active target proved its potential for the study of resonant elastic scattering in inverse kinematics with radioactive beams, when detection efficiency is of primary importance.

  2. Measurement of the Induced Proton Polarization Pn in the 12C(e, e', p) reaction

    SciTech Connect

    Woo, R J; Barkhuff, David; Bertozzi, William; Chen, Jian-ping; Dale, Dan; Dodson, G; Dow, K A; Epstein, Marty; Farkhondeh, Manouchehr; Finn, Mike; Gilad, Shalev; Jones, Mark K; Joo, Kyungseon; Kelly, James; Kowalski, Stanley; Lourie, Bob; Madey, Richard; Margaziotis, Dimitri; Markowitz, Pete; McIntyre, Justin; Mertz, Christoph; Milbrath, Brian; Mitchell, Joseph; Perdrisat, Charles F; Punjabi, Vina; Rutt, Paul; Sarty, Adam; Tieger, D; Tschalaer, C; Turchinetz, William; Ulmer, Paul E; Van Verst, S P; Vellidis, C; Warren, Glen; Weinstein, Lawrence

    1998-01-19

    The first measurements of the induced proton polarization Pn for the 12C(e,e',p) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (w,q) = (294 MeV, 765 MeV/c) and sampled a missing momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data for the 1 p3/2 shell. The data for the continuum suggest that both the 1s1/2 shell and underlying l > 1 configurations contribute.

  3. A New Decay Path in the {sup 12}C+{sup 16}O Radiative Capture Reaction

    SciTech Connect

    Courtin, S.; Lebhertz, D.; Haas, F.; Beck, C.; Michalon, A.; Salsac, M.-D.; Jenkins, D. G.; Marley, P.; Lister, C. J.

    2009-03-04

    The {sup 12}C({sup 16}O,{gamma}){sup 28}Si radiative capture reaction has been studied at energies close to the Coulomb barrier at Triumf (Vancouver) using the Dragon spectrometer and its associated BGO array. It has been observed that the {gamma} decay flux proceeds mainly via states around 10-11 MeV and via the direct feeding of the {sup 28}Si 3{sub 1}{sup -}(6879 keV) and 4{sub 2}{sup +}(6888 keV) deformed states. A discussion is presented about this selective feeding as well as perspectives for the use of novel detection systems for the study of light heavy-ion radiative capture reactions.

  4. Response of an FBX dosimeter to high LET 7Li and 12C ions

    NASA Astrophysics Data System (ADS)

    Bhat, N. N.; Choudhary, D.; Sarma, A.; Gupta, B. L.; Siddappa, K.

    2003-12-01

    We have carried out systematic studies on the response of ferrous sulphate-benzoic acid-xylenol orange (FBX)—a highly sensitive chemical dosimeter in liquid form to accelerated charged particles of different LET. Dosimeters were exposed in the form of thin layers to graded fluence of 7Li ion beam with three different energies Viz, 46, 38 and 27 MeV corresponding to average LETs of 6.3, 7.5 and 11 eV Å -1 and 12C ion beam with energy 45.6 MeV corresponding to average LET of 52.5 eV Å -1. From the investigations, the corresponding G(Fe +3) values were found to be (51.7±1.3)×10 -7, (35.4±0.7)×10 -7, (19.3±0.6)×10 -7 and (8.4±0.1)×10 -7 mol J -1, respectively. For gamma radiation, with estimated LET of 0.02 eV Å -1, G(Fe +3) value was observed to be (56.1±0.4)×10 -7 mol J -1. Clearly, G(Fe +3) values were found to decrease with increasing LET of the particle beam. However, the dosimeter showed no dependence on LET up to about 6 eV Å -1 unlike the Fricke dosimeter. The results confirm the response of FBX dosimeter is non-linear for doses exceeding 5 Gy for 60Co gamma rays. More importantly, the present study using 7Li and 12C ions clearly shows that response of the FBX dosimeter is linear for high LET radiations at low as well as high doses.

  5. X-ray diffraction study of the binding of the antisickling agent 12C79 to human hemoglobin

    SciTech Connect

    Wireko, R.C.; Abraham, D.J. )

    1991-03-15

    The hemoglobin binding site of the antisickling agent 12C79 has been determined by x-ray crystallography. 12C79 is recognized as one of the first molecules to reach clinical trials that was designed, de novo, from x-ray-determined atomic coordinates of a protein. Several previous attempts to verify the proposed Hb binding sites via crystallographic studies have failed. Using revised experimental procedures, the authors obtained 12C79-deoxhemoglobin crystals grown after reaction with oxyhemoglobin and cyanoborohydride reduction to stabilize the Schiff base linkage. The difference electron-density Fourier maps show that two 12C79 molecules bind covalently to both symmetry-related N-terminal amino groups of the hemoglobin {alpha} chains. This is in contrast to the original design that proposed the binding of one drug molecule that spans the molecular dyad to interact with both N-terminal {alpha}-amino groups.

  6. {sup {bold 6}}Li(vector)+{sup {bold 12}}C inelastic scattering at 30 and 50 MeV

    SciTech Connect

    Kerr, P.L.; Kemper, K.W.; Green, P.V.; Mohajeri, K.; Myers, E.G.; Schmidt, B.G.; Hnizdo, V.

    1996-09-01

    A complete set of analyzing powers (AP`s), {ital iT}{sub 11}, {ital T}{sub 20}, {ital T}{sub 21}, and {ital T}{sub 22}, for 50 MeV {sup 12}C({sup 6}Li(vector),{sup 6}Li) elastic scattering and inelastic scattering to the {sup 12}C(2{sup +}, 4.44 MeV), {sup 12}C(0{sup +}, 7.65 MeV), and {sup 12}C(3{sup {minus}}, 9.64 MeV) states over the center-of-mass (c.m.) angular range 10{degree}{endash}115{degree} is reported. In addition, cross sections for the excited states 3{sup +}(2.18 MeV), 2{sup +}(4.31 MeV), and 1{sup +}(5.65 MeV) of {sup 6}Li were measured by using the inverse-kinematics reaction {sup 6}Li({sup 12}C,{sup 12}C) at 100 MeV. A combined analysis of the new 50 MeV data and previous 30 MeV data has been carried out using the coupled-channels (CC) code FRESCO. The CC calculations use an optical potential with double-folded (DF) real central, Woods-Saxon imaginary central, and Thomas real spin-orbit (SO) potentials. Calculations include reorientation terms and coupling to the first three excited states of {sup 6}Li and the first two nonzerospin states of {sup 12}C. The {sup 6}Li coupling strengths were fixed by the measured {sup 6}Li excited-state cross sections. The elastic-scattering cross sections and A.P.`s are described well. The need for an explicit SO potential is apparent in the elastic and inelastic-scattering AP`s {ital iT}{sub 11}, more so at 30 MeV than at 50 MeV. The rank-2 AP`s up to 50{degree} c.m. arise mainly from ground-state reorientation effects. The DF potential normalization constant {ital N} approaches unity for the 50 MeV data. At both energies, the {sup 12}C(2{sup +}) cross sections are underestimated at large angles, and the description of the {sup 12}C(3{sup {minus}}) cross sections is poor in detail. The {sup 12}C(3{sup {minus}}) AP`s and the {sup 12}C(2{sup +}) {ital iT}{sub 11} are not reproduced at either energy. {copyright} {ital 1996 The American Physical Society.}

  7. Role of break-up processes in the fusion of the {sup 12}C+ {sup 52}Cr system

    SciTech Connect

    Amanuel, F. K.; Zelalem, B.; Chaubey, A. K.; Agarwal, Avinash; Rizvi, I. A.; Maheshwari, Anjana; Ahmed, Tauseef

    2011-08-15

    We present the results and analysis of our investigation of the role of break-up processes on the fusion of a {sup 12}C{sup 6+} beam with a {sup 52}Cr target near, at, and above the Coulomb barrier. In this experiment the excitation functions of evaporation residues produced via ({sup 12}C, 2n), ({sup 12}C, pxn), ({sup 12}C, {alpha}xn), and ({sup 12}C, {alpha}pxn) channels in a {sup 12}C + {sup 52}Cr reaction were measured at several beam energies ranging from {approx_equal}51 to 87 MeV by employing the recoil catcher technique followed by off-line {gamma}-ray spectrometry. The measured excitation functions were compared with theoretical values obtained using the pace4 statistical model code. Further, for a ({sup 12}C, p2n) channel the measured excitation function was compared with the predictions of the alice-91 code, which was chosen as it takes into account pre-equilibrium emissions. For non-{alpha}-emitting channels, the experimentally measured excitation functions--after correcting them for possible contributions from higher charge isobaric precursor decays--were, in general, found to be in good agreement with theoretical predictions. However, for {alpha}-emitting channels, the measured excitation functions had significantly more production cross sections than what pace4 predicted. This enhancement may be attributed to incomplete fusion processes. An attempt was made to estimate the incomplete fusion fraction in order to compare the relative importance of complete and incomplete fusion processes. The incomplete fusion fraction was found to be sensitive to the projectile energy and mass asymmetry of the entrance channel. We also discuss the results in terms of the impact of the frozen {alpha}-cluster structure of the {sup 12}C isotope on various fusion reactions.

  8. Relative Biological Effectiveness of 12C and 28Si radiation in C57BL/6J mice

    PubMed Central

    Suman, Shubhankar; Datta, Kamal; Trani, Daniela; Laiakis, Evagelia C.; Strawn, Steven J.; Fornace, Albert J.

    2014-01-01

    Study of heavy ion radiation–induced effects on mice could provide insight into the human health risks of space radiation exposure. The purpose of the present study is to assess the relative biological effectiveness (RBE) of 12C and 28Si ion radiation, which has not been reported previously in the literature. Female C57BL/6J mice (n=15) were irradiated using 4 to 8 Gy of 28Si (300MeV/nucleon energy; LET 70 keV/μm) and 5 to 8 Gy of 12C (290MeV/nucleon energy; LET 13 keV/μm) ions. Post-exposure, mice were monitored regularly and their survival observed for 30 days. The LD50/30 dose (the dose at which 50% lethality occurred by 30-days post-exposure) was calculated from the survival curve and was used to determine the RBE of 28Si and 12C in relation to γ radiation. The LD50/30 for 28Si and 12C ion is 5.17 Gy and 7.34 Gy respectively and the RBE in relation to γ radiation (LD50/30 – 7.25 Gy) is 1.4 for 28Si and 0.99 for 12C. Determination of RBE of 28Si and 12C for survival in mice is not only important for space radiation risk estimate studies, but also has implications for HZE radiation in cancer therapy. PMID:22562428

  9. Unambiguous identification of the second 2+ state in 12C and the structure of the Hoyle state.

    PubMed

    Zimmerman, W R; Ahmed, M W; Bromberger, B; Stave, S C; Breskin, A; Dangendorf, V; Delbar, Th; Gai, M; Henshaw, S S; Mueller, J M; Sun, C; Tittelmeier, K; Weller, H R; Wu, Y K

    2013-04-12

    The second J(π)=2+ state of 12C, predicted over 50 years ago as an excitation of the Hoyle state, has been unambiguously identified using the 12C(γ,α0)(8)Be reaction. The alpha particles produced by the photodisintegration of 12C were detected using an optical time projection chamber. Data were collected at beam energies between 9.1 and 10.7 MeV using the intense nearly monoenergetic gamma-ray beams at the HIγS facility. The measured angular distributions determine the cross section and the E1-E2 relative phases as a function of energy leading to an unambiguous identification of the second 2+ state in 12C at 10.03(11) MeV, with a total width of 800(130) keV and a ground state gamma-decay width of 60(10) meV; B(E2:2(2)+→0(1)+)=0.73(13)e(2)  fm(4) [or 0.45(8) W.u.]. The Hoyle state and its rotational 2+ state that are more extended than the ground state of 12C presents a challenge and constraints for models attempting to reveal the nature of three alpha-particle states in 12C. Specifically, it challenges the ab initio lattice effective field theory calculations that predict similar rms radii for the ground state and the Hoyle state. PMID:25167256

  10. Sensitivity of cross sections for elastic nucleus-nucleus scattering to halo nucleus density distributions

    SciTech Connect

    Alkhazov, G. D.; Sarantsev, V. V.

    2012-12-15

    In order to clear up the sensitivity of the nucleus-nucleus scattering to the nuclear matter distributions in exotic halo nuclei, we have calculated differential cross sections for elastic scattering of the {sup 6}He and {sup 11}Li nuclei on several nuclear targets at the energy of 0.8 GeV/nucleon with different assumed nuclear density distributions in {sup 6}He and {sup 11}Li.

  11. Elongated shape isomers in the {sup 36}Ar nucleus

    SciTech Connect

    Cseh, Jozsef; Darai, Judit; Sciani, Wagner; Otani, Yul; Lepine-Szily, Alinka; Benjamim, Elisangela A.; Chamon, Luiz Carlos; Filho, Rubens Lichtenthaeler

    2009-09-15

    A recent analysis of the {sup 12}C+{sup 24}Mg scattering [W. Sciani et al., Phys. Rev. C 80, 034319 (2009)] suggests the existence of a hyperdeformed band in the {sup 36}Ar nucleus, completely in line with the predictions of {alpha}[W. D. M. Rae and A. C. Merchant, Phys. Lett. B279, 207 (1992)] and binary cluster calculations [J. Cseh et al., Phys. Rev. C 70, 034311 (2004)]. Here we review the structural understanding of the superdeformed and the hyperdeformed states of {sup 36}Ar and present new results on the shape isomers as well. Special attention is paid to the clusterization of these states, which indicates the appropriate reaction channels for their formation.

  12. YF-12A and YF-12C in flight formation at dawn

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The YF-12A (60-6935) carries the 'coldwall' heat transfer pod on a pylon beneath the forward fuselage. The pod is seen with its insulating coating intact. In the background, the YF-12C flies photo chase. The coldwall project, supported by Langley Research Center, consisted of a stainless steel tube equipped with thermocouples and pressure-sensors. A special insulating coating covered the tube, which was chilled with liquid nitrogen. At Mach 3, the insulation could be pyrotechnically blown away from the tube, instantly exposing it to the thermal environment. The experiment caused many inflight difficulties, such as engine unstarts, but eventually researchers got a successful flight. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 60-6936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse

  13. Double Nucleus in M83

    NASA Astrophysics Data System (ADS)

    Mast, Damián; Díaz, Rubén J.; Agüero, M. Paz

    2006-03-01

    M83 is one of the nearest galaxies with enhanced nuclear star formation, and it presents one of the best opportunities to study the kinematics and physical properties of a circumnuclear starburst. Our three-dimensional spectroscopy data in the R band confirm the presence of a secondary nucleus or mass concentration (previously suggested by Thatte and coworkers). We determine the position of this hidden nucleus, which would be more massive than the visible one and was not detected in the optical Hubble Space Telescope images due, probably, to the strong dust extinction. Using a Keplerian approximation, we estimated for the optical nucleus a mass of (5.0+/-0.8)×106 Msolar/sini (r<1.5"), and for the hidden nucleus, located 4''+/-1'' to the northwest (position angle of 271deg+/-15deg) of the optical nucleus, a mass of (1.00+/-0.08)×107 Msolar/sini (r<1.5"). The emission-line ratio map also unveils the presence of a second circumnuclear ring structure, previously discovered by IR imaging (Elmegreen and coworkers). The data allow us to resolve the behavior of the interstellar medium inside the circumnuclear ring and around the binary mass concentration.

  14. Nucleus management with irrigating vectis.

    PubMed

    Srinivasan, Aravind

    2009-01-01

    The main objective in modern cataract surgery is to achieve a better unaided visual acuity with rapid post-surgical recovery and minimal surgery-related complications. Early visual rehabilitation and better unaided vision can be achieved only by reducing the incision size. In manual small incision cataract surgery (MSICS), incision is between 5.5 to 7 mm. Once the nucleus is prolapsed into the anterior chamber, it can be extracted through the tunnel. Nucleus extraction with an irrigating vectis is a very simple technique, which combines mechanical and hydrostatic forces to express out the nucleus. This technique is time-tested with good results and more than 95% of nuclei in MSICS are extracted in this way offering all the merits of phacoemulsification with the added benefits of having wider applicability, better safety, shorter learning curve and lower cost. PMID:19075403

  15. Cometary nucleus and active regions

    NASA Technical Reports Server (NTRS)

    Whipple, F. L.

    1984-01-01

    On the basis of the icy conglomerate model of cometary nuclei, various observations demonstrate the spotted nature of many or most nuclei, i.e., regions of unusual activity, either high or low. Rotation periods, spin axes and even precession of the axes are determined. The observational evidence for variations in activity over the surfaces of cometary nuclei are listed and discussed. On June 11 the comet IRAS-ARAKI-ALCOCK approached the Earth to a distance of 0.031 AU, the nearest since C/Lexell, 1770 I, providing a unique opportunity for near-nucleus observations. Preliminary analysis of these images establishes the spin axis of the nucleus, with an oblioquity to the orbit plane of approximately 50 deg, and a lag angle of sublimation approximately 35 deg from the solar meridian on the nucleus. Asymmetries of the inner coma suggests a crazy-quilt distribution of ices with differing volatility over the surface of the nucleus. The observations of Comet P/Homes 1892 III, exhibiting two 8-10 magnitude bursts, are carefully analyzed. The grazing encounter produced, besides the first great burst, an active area on the nucleus, which was rotating retrograde with a period of 16.3hr and inclination nearly 180 deg. After the first burst the total magnitude fell less than two magnitudes from November 7 to November 30 (barely naked eye) while the nuclear region remained diffuse or complex, rarely if ever showing a stellar appearance. The fading was much more rapid after the second burst. The grazing encounter distributed a volume of large chunks in the neighborhood of the nucleus, maintaining activity for weeks.

  16. Multimodal Imaging Using a 11B(d,nγ)12C Source

    NASA Astrophysics Data System (ADS)

    Nattress, Jason; Rose, Paul; Mayer, Michal; Wonders, Marc; Wilhelm, Kyle; Erickson, Anna; Jovanovic, Igor; Multimodal Imaging; Nuclear Detection (MIND) in Active Interrogation Collaboration

    2016-03-01

    Detection of shielded special nuclear material (SNM) still remains one of the greatest challenges facing nuclear security, where small signal-to-background ratios result from complex, challenging configurations of practical objects. Passive detection relies on the spontaneous radioactive decay, whereas active interrogation (AI) uses external probing radiation to identify and characterize the material. AI provides higher signal intensity, providing a more viable method for SNM detection. New and innovative approaches are needed to overcome specific application constraints, such as limited scanning time. We report on a new AI approach that integrates both neutron and gamma transmission signatures to deduce specific material properties that can be utilized to aid SNM identification. The approach uses a single AI source, single detector type imaging system based on the 11B(d,nγ)12C reaction and an array of eight EJ-309 liquid scintillators, respectively. An integral transmission imaging approach has been employed initially for both neutrons and photons, exploiting the detectors' particle discrimination properties. Representative object images using neutrons and photons will be presented.

  17. Electrophysiological effects of 12C on patients undergoing heavy ions therapy at GSI: a pilot study

    NASA Astrophysics Data System (ADS)

    Sannita, W. G.; Narici, L.; Debus, J.; Carozzo, S.; Saturno, M.; Schardt, D.; Schulz-Ertner, D.

    Phosphenes light flashes observed in space have been attributed to heavy ions interfering with the retina photoreceptors However their generating mechanisms are still undefined and neurons of the retina and non-ocular visual structures are as sensitive to ionizing agents as retinal photoreceptors Multiple sources are therefore possible that could question safety in manned space travel Patients undergoing 12C ion therapy of skull tumors also involving the anterior optic pathway often report phosphenes similar to those described by astronauts and volunteers in accelerator experiments In a pilot study their occurrence either within each beam pulse or shortly after it in case of very short pulses correlated with the beam position and local dose deposited near the optic nerve or eye during irradiation Further research is in progress at the GSI Biophysics facilities in Darmstadt FRG Purposes of the study are 1- to identify electrophysiological cortical concomitants of phosphenes 2- to correlate phosphenes with irradiated portions of the anterior visual pathways and with known basic mechanisms of vision and 3- to obtain information to be used in the understanding of phosphenes observed in space We will present preliminary results from the first measurements

  18. Charged current antineutrino reactions from {sup 12}C at MiniBooNE energies

    SciTech Connect

    Athar, M. Sajjad; Ahmad, Shakeb; Singh, S. K.

    2007-05-01

    A study of charged current induced antineutrino interactions from nuclei has been done for the intermediate energy antineutrinos and applied to {sup 12}C, relevant for ongoing experiment by MiniBooNE collaboration. The calculations have been done for the quasielastic and inelastic lepton production as well as for the incoherent and the coherent pion production processes. The calculations are done in local density approximation. In the case of the quasielastic reaction the effects of Pauli blocking, Fermi motion effects, renormalization of weak transition strengths in nuclear medium and the Coulomb distortion of the outgoing lepton have been taken into account. For the inelastic processes the calculations have been done in the {delta} dominance model and take into account the effect of Pauli blocking, Fermi motion of the nucleon, and renormalization of {delta} properties in a nuclear medium. The effect of final state interactions of pions is also taken into account. The numerical results for the total cross sections for the charged current quasielastic scattering and incoherent pion production processes are compared with earlier experimental results available in freon and freon-propane. It is found that nuclear medium effects give strong reduction in the cross sections leading to satisfactory agreement with the available data.

  19. Analysis of a Measurement of 12C(n,2n)11C Cross Sections

    NASA Astrophysics Data System (ADS)

    Hartshaw, Garrett; Love, Ian; Yuly, Mark; Padalino, Stephen; Russ, Megan; Bienstock, Mollie; Simone, Angela; Ellison, Drew; Desmitt, Holly; Massey, Thomas; Sangster, Craig

    2013-10-01

    In inertial confinement fusion (ICF), nuclear fusion reactions are initiated by bombarding a small fuel pellet with high power lasers. One ICF diagnostic tool involves placing graphite discs within the reaction chamber to determine the number of high-energy neutrons. This diagnostic requires accurate 12C(n, 2n)11C cross sections, which have not been previously well measured. An experiment to measure this cross section was conducted at Ohio University, in which DT neutrons irradiated polyethylene and graphite targets. The neutron flux was determined by counting recoil protons from the polyethylene in a silicon dE-E detector telescope. Preliminary cross sections were calculated using the incident neutron flux and the number of 11C nuclei in the graphite and polyethylene targets determined by counting, in a separate counting station, the gamma rays resulting from the positron decay of 11C. This poster will present the data analysis techniques used to determine these cross sections and the MCNPX simulation used to compute the corrections needed to account for the detector and target geometry. Funded in part by a LLE contract through the DOE.

  20. Carbon isotope ratio (13C/12C) of pine honey and detection of HFCS adulteration.

    PubMed

    Çinar, Serap B; Ekşi, Aziz; Coşkun, İlknur

    2014-08-15

    Carbon isotope ratio ((13)C/(12)C=δ(13)C) of 100 pine honey samples collected from 9 different localities by Mugla region (Turkey) in years 2006, 2007 and 2008 were investigated. The δ(13)Cprotein value of honey samples ranged between -23.7 and -26.6‰, while the δ(13)Choney value varied between -22.7 and -27‰. For 90% of the samples, the difference in the C isotope ratio of protein and honey fraction (δ(13)Cpro-δ(13)Chon) was -1.0‰ and/or higher. Therefore, it can be said that the generally anticipated minimum value of C isotope difference (-1.0‰) for honey is also valid for pine honey. On the other hand, C4 sugar value (%), which was calculated from the δ(13)Cpro-δ(13)Chon difference, was found to be linearly correlated with the amount of adulterant (HFCS) in pine honey. These results indicate that C4 sugar value is a powerful criteria for detecting HFCS adulteration in pine honey. The δ(13)Choney and δ(13)Cprotein-δ(13)Choney values of the samples did not show any significant differences in terms of both year and locality (P>0.05), while the δ(13)Cprotein values showed significant differences due to year (P<0.05) but not due to locality (P>0.05). PMID:24679745

  1. Elastic neutron scattering at 96 MeV from {sup 12}C and {sup 208}Pb

    SciTech Connect

    Klug, J.; Blomgren, J.; Atac, A.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Mermod, P.; Pomp, S.; Tippawan, U.; Nilsson, L.; Elmgren, K.; Olsson, N.; Jonsson, O.; Prokofiev, A.V.; Renberg, P.-U.; Nadel-Turonski, P.; Dangtip, S.; Phansuke, P.; Oesterlund, M.; Le Brun, C.

    2003-12-01

    A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL, has recently been installed at the 20-180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from {sup 12}C and {sup 208}Pb has been studied at 96 MeV in the 10 deg. -70 deg. interval. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions based on phenomenology or microscopic nuclear theory.

  2. 13C /12C Fractionation of methane during oxidation in a temperate forested soil

    NASA Astrophysics Data System (ADS)

    Tyler, Stanley C.; Crill, Patrick M.; Brailsford, Gordon W.

    1994-03-01

    We have made measurements of the 13C /12C fractionation of methane (CH 4) during microbial oxidation by an upland temperate soil from College Woods, New Hampshire, using both in situ and laboratory incubation measurements. Uptake rates of 1-4.8 mg CH 4/m 2/d were measured during the active season in New Hampshire while rates of uptake were 2.6-6.8 mg CH 4/m 2/d in jars used for incubation studies. The fractionation factor, calculated from field measurements, was α = 0.978 ± .004. This corresponds to a kinetic isotope effect (KIE) of ki 2/k 13 = 1.022 ± .004 . Only a small dependence on temperature was noted for air temperatures between 281 and 296 K. Our results indicate that the KIE of soil CH 4 oxidation is controlled by physical parameters based on gaseous diffusion into the soil. The implications of these results are discussed with respect to the global CH 4 budget and balancing CH 4 sources and sinks through the use of δ13CH 4 measurements.

  3. Photon scattering from 12C and 4He nuclei near the Δ(1232) resonance

    NASA Astrophysics Data System (ADS)

    Igarashi, R.; Bergstrom, J. C.; Caplan, H. S.; Doss, K. G. E.; Hallin, E. L.; Skopik, D. M.; Delli Carpini, D.; Booth, E. C.; McIntyre, E. K.; Miller, J. P.; Lucas, M. A.; MacGibbon, B. E.; Nathan, A. M.; Wells, D.

    1995-08-01

    Angular distributions for photon scattering from 12C and 4He have been measured using continuous wave bremsstrahlung from the Saskatchewan Accelerator Laboratory pulse stretcher ring. Data for carbon were taken at 158.8, 195.2, 197.2, 247.2, and 290.2 MeV end-point energies, and for helium were taken at an end-point energy of 158.8 MeV. A large NaI(Tl) gamma ray spectrometer with 1.7% resolution was used to detect the scattered photons at laboratory scattering angles ranging from 20° to 150°. The excellent energy resolution of the NaI detector allowed a separation of elastic from inelastic photon scattering for the first time at these energies. The angular distributions for elastic scattering are in only fair agreement with delta-hole theory and theory based on the optical theorem at forward angles, and completely disagree with theory at backward angles. Measured cross sections for inelastic scattering leading to the 4.43 MeV state in carbon are small compared to the elastic scattering at forward angles, but are dominant at backward angles. This experiment is the first to separate elastic from inelastic photon scattering at these energies.

  4. Formin' actin in the nucleus.

    PubMed

    Baarlink, Christian; Grosse, Robert

    2014-01-01

    Many if not most proteins can, under certain conditions, change cellular compartments, such as, for example, shuttling from the cytoplasm to the nucleus. Thus, many proteins may exert functions in various and very different subcellular locations, depending on the signaling context. A large amount of actin regulatory proteins has been detected in the mammalian cell nucleus, although their potential roles are much debated and are just beginning to emerge. Recently, members of the formin family of actin nucleators were also reported to dynamically localize to the nuclear environment. Here we discuss our findings that specific diaphanous-related formins can promote nuclear actin assembly in a signal-dependent manner. PMID:24637338

  5. Acridine: a versatile heterocyclic nucleus.

    PubMed

    Kumar, Ramesh; Kaur, Mandeep; Kumari, Meena

    2012-01-01

    Acridine is a heterocyclic nucleus. It plays an important role in various medicines. A number of therapeutic agents are based on acridine nucleus such as quinacrine (antimalarial), acriflavine and proflavine (antiseptics), ethacridine (abortifacient), amsacrine and nitracine (anticancer), and tacrine. Acridine is obtained from high boiling fraction of coal tar. It is also obtained in nature from plant and marine sources. Acridine undergoes a number of reactions such as nucleophilic addition, electrophilic substitution, oxidation, reduction, reductive alkylation and photoalkylation. The present review article summarizes the synthesis, reaction, literature review and pharmaceutical importance of acridine. PMID:22574501

  6. Including higher energy data in the R-matrix extrapolation of 12C(α , γ) 16O

    NASA Astrophysics Data System (ADS)

    Deboer, R.; Uberseder, E.; Azuma, R. E.; Best, A.; Brune, C.; Goerres, J.; Sayre, D.; Smith, K.; Wiescher, M.

    2015-10-01

    The phenomenological R-matrix technique has proved to be very successful in describing the cross sections of interest to nuclear astrophysics. One of the key reactions is 12C(α , γ) 16O, which has frequently been analyzed using R-matrix but usually over a limited energy range. This talk will present an analysis that, for the first time, extends above the proton and α1 separation energies taking advantage of a large amount of additional data. The analysis uses the new publicly released JINA R-matrix code AZURE2. The traditional reaction channels of 12C(α , γ) 16O, 12C(α ,α0) 12, and 16N(βα) 12C are included but are now accompanied by the higher energy reactions. By explicitly including higher energy levels, the uncertainty in the extrapolation of the cross section is significantly reduced. This is accomplished by more stringent constraints on interference combination and background poles by the additional higher energy data and by considering new information about subthresold states from transfer reactions. The result is the most comprehensive R-matrix analysis of the 12C(α , γ) 16O reaction to date. This research was supported in part by the ND CRC and funded by the NSF through Grant No. Phys-0758100, and JINA through Grant No. Phys-0822648.

  7. RF-bunching of relativistic 12C3+ ion beam for laser cooling experiment at the CSRe

    NASA Astrophysics Data System (ADS)

    Wang, H. B.; Wen, W. Q.; Ma, X.; Huang, Z. K.; Zhang, D. C.; Bussmann, M.; Winters, D. F. A.; Yuan, Y. J.; Zhu, X. L.; Zhao, D. M.; Mao, R. S.; Li, J.; Mao, L. J.; Yang, J. C.; Zhao, H. W.; Xu, H. S.; Xiao, G. Q.; Xia, J. W.

    2015-01-01

    To prepare the upcoming experiment of laser cooling of relativistic 12C3+ ion beams at the experimental cooler storage ring (CSRe), a test experiment was performed with 12C3+ ion beams at an energy of 122 MeV/u on the CSRe, at the Institute of Modern Physics, Lanzhou, China. In this experiment, the main storage ring of CSRm was employed to accumulate and accelerate the ion beam which was injected into the CSRe for the experiments. The number of 12C3+ ions at the CSRe reached 5×108 for every injection, which satisfied the experimental requirement. To fulfil the laser cooling experiment, the 12C3+ ion beams were bunched by sinusoidal waveforms with fixed and sweeping frequencies, respectively. A resonant Schottky pick-up was employed to record the Schottky spectra of these ion beams. The test experimental results demonstrated that the RF-buncher and diagnostic systems at the CSRe worked well and the CSRe was very stable with 12C3+ ion beams, hereby the CSRe is suitable for laser cooling experiment.

  8. Functionalized active-nucleus complex sensor

    DOEpatents

    Pines, Alexander; Wemmer, David E.; Spence, Megan; Rubin, Seth

    2003-11-25

    A functionalized active-nucleus complex sensor that selectively associates with one or more target species, and a method for assaying and screening for one or a plurality of target species utilizing one or a plurality of functionalized active-nucleus complexes with at least two of the functionalized active-nucleus complexes having an attraction affinity to different corresponding target species. The functionalized active-nucleus complex has an active-nucleus and a targeting carrier. The method involves functionalizing an active-nucleus, for each functionalized active-nucleus complex, by incorporating the active-nucleus into a macromolucular or molecular complex that is capable of binding one of the target species and then bringing the macromolecular or molecular complexes into contact with the target species and detecting the occurrence of or change in a nuclear magnetic resonance signal from each of the active-nuclei in each of the functionalized active-nucleus complexes.

  9. Comparison of characteristics of {Delta}{sup 0}(1232) produced in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c

    SciTech Connect

    Olimov, Kh. K. Haseeb, Mahnaz Q. Khan, Imran

    2012-04-15

    Reconstructed momentum, transverse momentum, kinetic energy, rapidity, and emission angle distributions along with their mean values were compared for {Delta}{sup 0}(1232) resonances produced in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c. Mean momentum, transverse momentum, and rapidity of protons and negative pions coming from {Delta}{sup 0}(1232) decay were extracted and compared with the corresponding mean values for protons and {pi}{sup -} mesons in experiment and the relevant model calculations.

  10. Investigation of the Herzberg (C1Σ+→A1Π) band system in 12C17O

    NASA Astrophysics Data System (ADS)

    Hakalla, Rafał

    2015-10-01

    The C→A (0,1), (0,2) and (0,3) rovibronic bands of the less-abundant 12C17O isotopologue are studied in high resolution using a high-accuracy dispersive optical spectroscopy in the region of 22,800-26,100 cm-1. Calibration with respect to simultaneously recorded thorium atomic lines, obtained from several overlapped orders of the spectrum in the visible range, as well as a stainless steel hollow-cathode molecular lamp with two anodes, yields an absolute accuracy of wavenumbers measurements of about 0.0025 cm-1 for the CO spectra. All 261 spectra lines of the Herzberg band system in 12C17O, up to Jmax=34, were precisely measured and rotationally analyzed. As a result, the merged rotational constants and rotational equilibrium constants for the C1Σ+ Rydberg state, as well as the band origins, the isotope shifts, the RKR turning points, Franck-Condon factors, relative intensities, and r-centroids of the C→A system in the 12C17O isotopologue were obtained. An experimental RKR potential energy curve and vibrational levels of the C1Σ+ state in 12C17O together with highly excited k3Π, c3Π, E1Π, B1Σ+ and D‧1Σ+ states lying in the region between the first dissociation limit and the ionization potential of CO were plotted. A detailed investigation of possible perturbations that should occur in the C1Σ+(υ=0) Rydberg state of less-abundant 12C17O isotopologue in the close vicinity of the k3Π(υ=1, 2) and c3Π(υ=0) states in the region 92,000 cm-1 was performed. In the A1Π, υ=3 state of 12C17O, extensive, multi-state rotational perturbations were found and analyzed. Also, a global isotopic analysis of the C1Σ+ Rydberg state was carried out in the 12C16O, 12C17O, 13C16O, 12C18O, 13C17O, and 13C18O as well as in 14C16O and 14C18O isotopologues. This analysis enabled us to determine, amongst others, the vibrational equilibrium constants in 12C17O for the C1Σ+ state, to improve these constants in the 12C16O, 13C16O, 12C18O, 13C17O, and 13C18O isotopologues and

  11. Higgs and Particle Production in Nucleus-Nucleus Collisions

    NASA Astrophysics Data System (ADS)

    Liu, Zhe

    We apply a diagrammatic approach to study Higgs boson, a color-neutral heavy particle, pro- duction in nucleus-nucleus collisions in the saturation framework without quantum evolution. We assume the strong coupling constant much smaller than one. Due to the heavy mass and colorless nature of Higgs particle, final state interactions are absent in our calculation. In order to treat the two nuclei dynamically symmetric, we use the Coulomb gauge which gives the appropriate light cone gauge for each nucleus. To further eliminate initial state interactions we choose specific prescriptions in the light cone propagators. We start the calculation from only two nucleons in each nucleus and then demonstrate how to generalize the calculation to higher orders diagrammatically. We simplify the diagrams by the Slavnov-Taylor-Ward identities. The resulting cross section is factorized into a product of two Weizsacker-Williams gluon distributions of the two nuclei when the transverse momentum of the produced scalar particle is around the saturation momentum. To our knowledge this is the first process where an exact analytic formula has been formed for a physical process, involving momenta on the order of the saturation momentum, in nucleus-nucleus collisions in the quasi-classical approximation. Since we have performed the calculation in an unconventional gauge choice, we further confirm our results in Feynman gauge where the Weizsacker-Williams gluon distribution is interpreted as a transverse momentum broadening of a hard gluons traversing a nuclear medium. The transverse momentum factorization manifests itself in light cone gauge but not so clearly in Feynman gauge. In saturation physics there are two different unintegrated gluon distributions usually encountered in the literature: the Weizsacker-Williams gluon distribution and the dipole gluon distribution. The first gluon distribution is constructed by solving classical Yang-Mills equation of motion in the Mc

  12. Neutrino-nucleus reactions based on recent structure studies

    SciTech Connect

    Suzuki, Toshio

    2015-05-15

    Neutrino-nucleus reactions are studied with the use of new shell model Hamiltonians, which have proper tensor components in the interactions and prove to be successful in the description of Gamow-Teller (GT) strengths in nuclei. The new Hamiltonians are applied to obtain new neutrino-nucleus reaction cross sections in {sup 12}C, {sup 13}C, {sup 56}Fe and {sup 56}Ni induced by solar and supernova neutrinos. The element synthesis by neutrino processes in supernova explosions is discussed with the new cross sections. The enhancement of the production yields of {sup 7}Li, {sup 11}B and {sup 55}Mn is obtained while fragmented GT strength in {sup 56}Ni with two-peak structure is found to result in smaller e-capture rates at stellar environments. The monopole-based universal interaction with tensor force of π+ρ meson exchanges is used to evaluate GT strength in {sup 40}Ar and ν-induced reactions on {sup 40}Ar. It is found to reproduce well the experimental GT strength in {sup 40}Ar.

  13. S-Factor measurement of the 12C(p,γ)13N reaction in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Stöckel, Klaus; Reinhardt, Tobias P.; Akhmadaliev, S.; Bemmerer, D.; Gohl, St.; Reinicke, S.; Schmidt, K.; Serfling, M.; Szücs, T.; Takács, M. P.; Wagner, L.; Zuber, K.

    2015-05-01

    Hydrogen rich solid targets have been developed and produced to investigate the 12C(p, γ)13N reaction in inverse kinematics. The SRIM simulation software has been used to determine the parameters for ion implantation in various materials. Nuclear Resonant Reacton Analysis (NRRA) with the resonant reaction 15N(p, αγ)12C has been carried out to measure the hydrogen content of the produced targets. Measurements of the produced targets at the energy range from Ecm = 577 keV down to Ecm = 191 keV, were performed at the 3-MV Tandetron of Helmholtz-Zentrum Dresden-Rossendorf (HZDR).

  14. LED-based Fourier transform spectroscopy of 16O12C18O and 12C18O2 in the 11,260-11,430 cm-1 range

    NASA Astrophysics Data System (ADS)

    Serdyukov, V. I.; Sinitsa, L. N.; Lugovskoi, A. A.; Borkov, Yu. G.; Tashkun, S. A.; Perevalov, V. I.

    2016-07-01

    The absorption spectrum of the 16O12C18O and 12C18O2 carbon dioxide isotopologues has been recorded in the 11,260- 11,430 cm-1 spectral range using Bruker IFS 125 HR Fourier transform spectrometer with resolution 0.05 cm-1 at temperature 297 K and path length 24 m. The 18O enriched sample of carbon dioxide at total pressure 96.5 mbar was used for these purposes. The spectrometer used LED emitter as a light source. This gave possibility to reach the minimal detectable absorption coefficient αmin~1.4×10-7 cm-1 using 23,328 scans. In the recorded spectrum we have assigned the 00051-00001 band for both 16O12C18O and 12C18O2 isotopologues using the predictions performed within the framework of the method of effective operators. The line positions and intensities of the observed bands are found. The comparison of the observed and predicted line positions and intensities is performed confirming good accuracy of the predictions. The spectroscopic parameters for the observed bands are determined.

  15. Limits for the 3[alpha] branching ratio of the decay of the 7. 65 MeV, 0[sub 2][sup +] state in [sup 12]C

    SciTech Connect

    Freer, M.; Wuosmaa, A.H.; Betts, R.R.; Henderson, D.J.; Wilt, P. ); Zurmuehle, R.W.; Balamuth, D.P.; Barrow, S.; Benton, D.; Li, Q.; Liu, Z.; Miao, Y. )

    1994-04-01

    A study of the [sup 12]C([sup 12]C, 3[alpha])[sup 12]C reaction has been performed in order to determine the magnitude of the process by which the 7.65 MeV, 0[sub 2][sup +], state in [sup 12]C breaks up directly into three alpha particles, in contrast to the sequential decay through [sup 8]Be. The strength of this decay channel has important implications for the production rate of [sup 12]C in stellar nucleosynthesis. The present measurement indicates that the contribution of this decay process to the alpha width, [Gamma][sub [alpha

  16. Dynamical nucleus-nucleus potential at short distances

    SciTech Connect

    Jiang Yongying; Wang Ning; Li Zhuxia; Scheid, Werner

    2010-04-15

    The dynamical nucleus-nucleus potentials for fusion reactions {sup 40}Ca+{sup 40}Ca, {sup 48}Ca+{sup 208}Pb, and {sup 126}Sn+{sup 130}Te are studied with the improved quantum molecular dynamics model together with the extended Thomas-Fermi approximation for the kinetic energies of nuclei. The obtained fusion barrier for {sup 40}Ca+{sup 40}Ca is in good agreement with the extracted fusion barrier from the measured fusion excitation function, and the depths of the fusion pockets are close to the results of time-dependent Hartree-Fock calculations. The energy dependence of the fusion barrier is also investigated. The fusion pocket becomes shallow for a heavy fusion system and almost disappears for heavy nearly symmetric systems, and the obtained potential at short distances is higher than the adiabatic potential.

  17. Azimuthal correlation and collective behavior in nucleus-nucleus collisions

    SciTech Connect

    Mali, P.; Mukhopadhyay, A. Sarkar, S.; Singh, G.

    2015-03-15

    Various flow effects of nuclear and hadronic origin are investigated in nucleus-nucleus collisions. Nuclear emulsion data collected from {sup 84}Kr + Ag/Br interaction at an incident energy of 1.52 GeV per nucleon and from {sup 28}Si + Ag/Br interaction at an incident energy of 14.5 GeV per nucleon are used in the investigation. The transverse momentum distribution and the flow angle analysis show that collective behavior, like a bounce-off effect of the projectile spectators and a sidesplash effect of the target spectators, are present in our event samples. From an azimuthal angle analysis of the data we also see a direct flow of the projectile fragments and of the produced charged particles. On the other hand, for both data samples the target fragments exhibit a reverse flow, while the projectile fragments exhibit an elliptic flow. Relevant flow parameters are measured.

  18. Analysis of relativistic nucleus-nucleus interactions in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1987-01-01

    The development of a computer-assisted method is reported for the determination of the angular distribution data for secondary particles produced in relativistic nucleus-nucleus collisions in emulsions. The method is applied to emulsion detectors that were placed in a constant, uniform magnetic field and exposed to beams of 60 and 200 GeV/nucleon O-16 ions at the Super Proton Synchrotron (SPS) of the European Center for Nuclear Research (CERN). Linear regression analysis is used to determine the azimuthal and polar emission angles from measured track coordinate data. The software, written in BASIC, is designed to be machine independent, and adaptable to an automated system for acquiring the track coordinates. The fitting algorithm is deterministic, and takes into account the experimental uncertainty in the measured points. Further, a procedure for using the track data to estimate the linear momenta of the charged particles observed in the detectors is included.

  19. Single nucleon emission in relativistic nucleus-nucleus reactions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Townsend, Lawrence W.

    1992-01-01

    Significant discrepancies between theory and experiment have previously been noted for nucleon emission via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work investigates the hypothesis that these discrepancies have arisen due to uncertainties about how to deduce the experimental electromagnetic cross section from the total measured cross section. An optical-model calculation of single neutron removal is added to electromagnetic cross sections and compared to the total experimental cross sections. Good agreement is found thereby resolving some of the earlier noted discrepancies. A detailed comparison to the recent work of Benesh, Cook, and Vary is made for both the impact parameter and the nuclear cross section. Good agreement is obtained giving an independent confirmation of the parameterized formulas developed by those authors.

  20. VizieR Online Data Catalog: 12C16O lines in Arcturus IR spectrum

    NASA Astrophysics Data System (ADS)

    Tsuji T.

    2009-06-01

    Based on the Infrared Atlas of the Arcturus Spectrum by Hinkle, Wallace, and Livingston (1995, Cat. ), we measured line-depth, full-width at half-maximum (FWHM), and equivalent width (EW) of 12C16O lines including fundamental, first and second overtone bands, and the results are given in table2. We used the electronic version of the ratioed spectra in our measurement and the tabulated results are measured raw data without any correction yet. The resulting data are used to investigate the nature of the infrared spectrum of Arcturus. It is found that only the weak lines (log(W/nu)<-4.75) can be analyzed consistently on the basis of the classical line-formation theory and hence can be used to extract the nature of the photosphere: We found logAC=7.97 (on the scale of log AH=12.00), micro and macro turbulent velocities to be 1.87 and 3.47km/s, respectively, for the photosphere. The nature of CO lines, however, shows abrupt change at about log(W/nu)=-4.75: The EWs of the lines larger than this limit can no longer be accounted for by the photospheric parameters determined from the weaker lines. A more simple demonstration of this fact is that the curves-of-growth of overtone as well as of fundamental CO lines show unpredictable upturn at about log(W/nu)=-4.75. Similar unusual behaviors of empirical curves-of-growth are found in other red giant and supergiant stars, and it looks as if the curves-of-growth are composite of at least two components of different origins. We think it difficult to understand such empirical data as due to the classical photosphere alone, and infrared spectra of cool luminous stars including Arcturus should be hybrid in nature. Although strong lines of the CO fundamentals show strengthening, the weaker lines show slight weakening, and we consider a possibility that these results are due to absorption/emission by the molecular clouds formed in the extended atmosphere. In cooler giant and supergiant stars in which CO lines show

  1. Coral 13C/12C records of vertical seafloor displacement during megathrust earthquakes west of Sumatra

    NASA Astrophysics Data System (ADS)

    Gagan, Michael K.; Sosdian, Sindia M.; Scott-Gagan, Heather; Sieh, Kerry; Hantoro, Wahyoe S.; Natawidjaja, Danny H.; Briggs, Richard W.; Suwargadi, Bambang W.; Rifai, Hamdi

    2015-12-01

    The recent surge of megathrust earthquakes and tsunami disasters has highlighted the need for a comprehensive understanding of earthquake cycles along convergent plate boundaries. Space geodesy has been used to document recent crustal deformation patterns with unprecedented precision, however the production of long paleogeodetic records of vertical seafloor motion is still a major challenge. Here we show that carbon isotope ratios (δ13C) in the skeletons of massive Porites corals from west Sumatra record abrupt changes in light exposure resulting from coseismic seafloor displacements. Validation of the method is based on the coral δ13C response to uplift (and subsidence) produced by the March 2005 Mw 8.6 Nias-Simeulue earthquake, and uplift further south around Sipora Island during a M ∼ 8.4 megathrust earthquake in February 1797. At Nias, the average step-change in coral δ13C was 0.6 ± 0.1 ‰ /m for coseismic displacements of +1.8 m and -0.4 m in 2005. At Sipora, a distinct change in Porites microatoll growth morphology marks coseismic uplift of 0.7 m in 1797. In this shallow water setting, with a steep light attenuation gradient, the step-change in microatoll δ13C is 2.3 ‰ /m, nearly four times greater than for the Nias Porites. Considering the natural variability in coral skeletal δ13C, we show that the lower detection limit of the method is around 0.2 m of vertical seafloor motion. Analysis of vertical displacement for well-documented earthquakes suggests this sensitivity equates to shallow events exceeding Mw ∼ 7.2 in central megathrust and back-arc thrust fault settings. Our findings indicate that the coral 13C /12C paleogeodesy technique could be applied to convergent tectonic margins throughout the tropical western Pacific and eastern Indian oceans, which host prolific coral reefs, and some of the world's greatest earthquake catastrophes. While our focus here is the link between coral δ13C, light exposure and coseismic crustal deformation, the

  2. Nuclear data for neutron and proton interactions with 12C in the energy range 0-10 GeV.

    PubMed

    Pearlstein, S

    1993-08-01

    Nuclear model codes and nuclear systematics are used to give a first approximation to data for nucleons interacting with a 12C target over the range 0-10 GeV. Where there are experiments, the trial values are replaced by an eye guide through the measurements. The evaluated data have been placed in computerized form and are available for distribution. PMID:8392503

  3. Comment on 'Low-energy cross sections in the {sup 12}C({alpha},{gamma}){sup 16}O reaction'

    SciTech Connect

    Descouvemont, P.; Dufour, M.

    2010-02-15

    We show that the E1 and E2 S factors recommended by Katsuma [Phys. Rev. C 78, 034606 (2008)] do not include well-known constraints and that the model is inappropriate for the {sup 12}C({alpha},{gamma}){sup 16}O reaction.

  4. Coupled-channel analysis of neutron scattering from /sup 12/C between 9 and 15 MeV

    SciTech Connect

    Hansen, L.F.; Meigooni, A.S.

    1986-07-01

    A deformed and energy dependent phenomenological optical model potential and coupled-channel formalism for deformed nuclei have been used in the analysis of elastic and inelastic (Q = 4.439 MeV) scattering, and analyzing power for neutrons scattered from /sup 12/C in the energy range of 9 to 15 MeV. 6 refs., 1 fig., 1 tab.

  5. Four-body calculation of 12C(α, γ)16O radiative capture reaction at stellar energies

    NASA Astrophysics Data System (ADS)

    Sadeghi, H.; Firoozabadi, M. M.

    2016-01-01

    On the basis of the four-alphamodel, the 12C(α, γ)16Oradiative capture process is investigated by using the four-body Faddeev-Yakubovsky equations as well as the two- and three-body electromagnetic currents. The present calculation is an application of our current conservation realistic potentials method for the 12C(α, γ)16Oradiative capture process. This work clears the way formore refinedmodels of radiative capture based on two- and three-body realistic potentials and current conservation. The calculation is carried out by considering the 4He + 12C (1 + 3) and the 8Be + 8Be (2 + 2) subamplitudes, respectively. Radiative capture 12C(α, γ)16Oreaction is one of the most important reactions in nuclear astrophysics. For this reaction, the electric dipole transitions between states with the same isospin are forbidden in the first order. Because the state 1+ and 0+ ground state nuclei 16O have zero isospin, thus the electric dipole radiations are not at the first order between two levels and electric dipole radiation will be the second order and electric dipole radiation is the same order as the electric quadrupole radiation. Therefore, we must consider the effects of both radiations. In comparison with other theoretical methods and available experimental data, good agreement is achieved for the E 1 and E 2 contribution to the cross section and the astrophysical S factor for this process.

  6. General last-step labeling of biomolecule-based substrates by [12C], [13C], and [11C] carbon monoxide.

    PubMed

    Cornilleau, Thomas; Audrain, Hélène; Guillemet, Aude; Hermange, Philippe; Fouquet, Eric

    2015-01-16

    Alkaloid-, steroid-, biotin-, carbohydrate-, nucleoside-, and peptide-based bioconjugates are easily labeled with CO by a last-step palladium-catalyzed carbonylation. The choice of the [(12)C], [(13)C], or [(11)C] isotope opens the way to a new class of potential tracers or ligands easily available for various applications. PMID:25562588

  7. Hummingbird Comet Nucleus Analysis Mission

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel; Carle, Glenn C.; Lasher, Larry E.

    2000-01-01

    Hummingbird is a highly focused scientific mission, proposed to NASA s Discovery Program, designed to address the highest priority questions in cometary science-that of the chemical composition of the cometary nucleus. After rendezvous with the comet, Hummingbird would first methodically image and map the comet, then collect and analyze dust, ice and gases from the cometary atmosphere to enrich characterization of the comet and support landing site selection. Then, like its namesake, Hummingbird would carefully descend to a pre-selected surface site obtaining a high-resolution image, gather a surface material sample, acquire surface temperature and then immediately return to orbit for detailed chemical and elemental analyses followed by a high resolution post-sampling image of the site. Hummingbird s analytical laboratory contains instrumentation for a comprehensive molecular and elemental analysis of the cometary nucleus as well as an innovative surface sample acquisition device.

  8. RCNP E398 {sup 16}O,{sup 12}C(p,p’) experiment: Measurement of the γ-ray emission probability from giant resonances in relation to {sup 16}O,{sup 12}C(ν,ν’) reactions

    SciTech Connect

    Ou, I.; Yamada, Y.; Mori, T.; Yano, T.; Sakuda, M.; Tamii, A.; Suzuki, T.; Yosoi, M.; Aoi, N.; Ideguchi, E.; Hashimoto, T.; Miki, K.; Ito, T.; Iwamoto, C.; Yamamoto, T.; Akimune, H.

    2015-05-15

    We propose to measure the γ-ray emission probability from excited states above 5 MeV including giant resonance of {sup 16}O and {sup 12}C as a function of excitation energy in 1-MeV step. Here, we measure both the excitation energy (E{sub x}=5-30MeV) at the forward scattering angles (0°-3°) of the {sup 16}O, {sup 12}C (p, p’) reaction using Grand-Raiden Spectrometer and the energy of γ-rays (E{sub γ}) using an array of NaI(Tl) counters. The purpose of the experiment is to provide the basic and important information not only for the γ-ray production from primary neutral-current neutrino-oxygen (-carbon) interactions but also for that from the secondary hadronic (neutron-oxygen and -carbon) interactions.

  9. Photoproduction of lepton pairs in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies

    SciTech Connect

    Moreira, B. D.; Goncalves, V. P.; De Santana Amaral, J. T.

    2013-03-25

    In this contribution we study coherent interactions as a probe of the nonlinear effects in the Quantum Electrodynamics (QED). In particular, we study the multiphoton effects in the production of leptons pairs for proton-nucleus and nucleus-nucleus collisions for heavy nuclei. In the proton-nucleus we assume the ultrarelativistic proton as a source of photons and estimate the photoproduction of lepton pairs on nuclei at RHIC and LHC energies considering the multiphoton effects associated to multiple rescattering of the projectile photon on the proton of the nucleus. In nucleus - nucleus colllisions we consider the two nuclei as a source of photons. As each scattering contributes with a factor {alpha}Z to the cross section, this contribution must be taken into account for heavy nuclei. We consider the Coulomb corrections to calculate themultiple scatterings and estimate the total cross section for muon and tau pair production in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies.

  10. Characterization of fragment emission in {sup 20}Ne(7-10 MeV/nucleon)+{sup 12}C reactions

    SciTech Connect

    Dey, Aparajita; Bhattacharya, C.; Bhattacharya, S.; Kundu, S.; Banerjee, K.; Mukhopadhyay, S.; Gupta, D.; Bhattacharjee, T.; Banerjee, S. R.; Bhattacharyya, S.; Rana, T. K.; Basu, S. K.; Saha, R.; Krishan, K.; Mukherjee, A.; Bandopadhyay, D.; Beck, C.

    2007-09-15

    The inclusive energy distributions of the complex fragments (3{<=}Z{<=}7) emitted from the bombardment of {sup 12}C by {sup 20}Ne beams with incident energies between 145 and 200 MeV have been measured in the angular range 10 deg.{<=}{theta}{sub lab}{<=}50 deg. Damped fragment yields in all the cases have been found to have the characteristic of emission from fully energy equilibrated composites. The binary fragment yields are compared with the standard statistical model predictions. Whereas Li and Be fragments yields are in agreement with statistical-model calculations, enhanced yields of entrance channel fragments (5{<=}Z{<=}7) indicate the survival of orbiting-like process in {sup 20}Ne+{sup 12}C system at these energies.

  11. Resistance of Bacillus subtilis spores to 12C ion beams, stimulation of high-energy charged particles in space

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Dang, Bingrong; Li, Junxiong; Chen, Jinsong; Liu, Mei; Liu, Zhiheng; Zhang, Lixin

    To monitor the response of live microbes in space radiation environment with high-energy charged particles, we carry out ground stimulation radiation experiments. Spores of Bacillus (CGMCC 1.1849) species are one of the model systems used for astro- and radiobiological studies. (12) C ion beams served as stimulated space radiation from 5gry, 10gry, 20gry, 40gry, to 80gry at a rate of 15gry/min Death rates are measured and mutant strains are isolated. Five representative strains are analyzed for their corresponding gene sequences, protein sequences and gene expression index of DNA repair system gene recA and recO. The statistic results showed the strains resistance to (12) C ion beams radiation is partially due to the increase of gene expression index of recA and recO. In conclusion, our research provide a surrogate system to monitor the live microbial response in resistant to space radiation environment.

  12. New decay branches of the radiative capture reaction {sup 12}C({sup 16}O,{gamma}){sup 28}Si

    SciTech Connect

    Lebhertz, D.; Courtin, S.; Haas, F.; Salsac, M.-D.; Beck, C.; Michalon, A.; Rousseau, M.; Marley, P. L.; Glover, R. G.; Kent, P. E.; Hutcheon, D. A.; Davis, C.; Pearson, J. E.

    2009-01-28

    Resonances in the {sup 12}C({sup 16}O,{gamma}){sup 28}Si radiative capture process at energies around the Coulomb barrier have been probed using the very selective 0 deg. Dragon spectrometer at Triumf and its associated BGO {gamma}-array. For the first time the full level scheme involved in this process has been measured and shows previously unobserved {gamma}-decay to doorway states around 11 MeV in {sup 28}Si.

  13. Background reduction system of {sup 4}He({sup 12}C,{sup 16}O)gamma at KUTL

    SciTech Connect

    Taniguchi, M.; Sagara, K.; Teranishi, T.; Fujita, K.; Iwabuchi, R.; Gotoh, T.; Nakano, K.; Oba, N.

    2010-06-01

    The C-alpha reaction is one of the most important reactions in astrophysics. At Kyushu University Tandem accelerator Laboratory (KUTL), a high detective efficiency measurement has been made by adopting inverse kinematics: {sup 12}C beam is injected on windowless {sup 4}He gas target. In this experiment, a powerful background reduction system is necessary. We describe the effectiveness of the background system consisting of recoil mass separator, a long time chopper, and new movable slits.

  14. Early effects of low dose 12C6+ ion or X-ray irradiation on human peripheral blood lymphocytes

    NASA Astrophysics Data System (ADS)

    Chen, Yingtai; Li, Yumin; Zhang, Hong; Xie, Yi; Chen, Xuezhong; Ren, Jinyu; Zhang, Xiaowei; Zhu, Zijiang; Liu, Hongliang; Zhang, Yawei

    2010-04-01

    The aim of this study was to estimate the acute effects of low dose 12C6+ ions or X-ray radiation on human immune function. The human peripheral blood lymphocytes (HPBL) of seven healthy donors were exposed to 0.05 Gy 12C6+ ions or X-ray radiation and cell responses were measured at 24 h after exposure. The cytotoxic activities of HPBL were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT); the percentages of T and NK cells subsets were detected by flow cytometry; mRNA expression of interleukin (IL)-2, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were examined by real time quantitative RT-PCR (qRT-PCR); and these cytokines protein levels in supernatant of cultured cells were assayed by enzyme-linked immunosorbent assays (ELISA). The results showed that the cytotoxic activity of HPBL, mRNA expression of IL-2, IFN-γ and TNF-α in HPBL and their protein levels in supernatant were significantly increased at 24 h after exposure to 0.05 Gy 12C6+ ions radiation and the effects were stronger than observed for X-ray exposure. However, there was no significant change in the percentage of T and NK cells subsets of HPBL. These results suggested that 0.05 Gy high linear energy transfer (LET) 12C6+ radiation was a more effective approach to host immune enhancement than that of low LET X-ray. We conclude that cytokines production might be used as sensitive indicators of acute response to LDI.

  15. Cluster folding model for /sup 12/C(/sup 6/Li,/sup 6/Li) scattering at 156 Mev

    SciTech Connect

    Majka, Z.; Gils, H.J.; Rebel, H.

    1982-06-01

    A double-folding cluster model generated from d-..cap alpha.. and ..cap alpha..-..cap alpha.. interactions and internal cluster wave functions of the projectile and the target nuclei is proposed to describe the differential cross sections for /sup 6/Li elastic scattering from /sup 12/C at 156 MeV. Results of these calculations are compared with standard double-folding models and the phenomenological optical model predictions.

  16. The Simultaneous Investigation of the {sup 6}He+{sup 12}C Reaction Observables Using Folding Potential

    SciTech Connect

    Karakoc, M.; Kucuk, Y.; Boztosun, I.

    2008-11-11

    We investigate the observables of the {sup 6}He+{sup 12}C system by using coupled-channels Born approximation. We try to address the role of the transfer channels in explaining the reaction observables. We noticed the inclusion of the transfer channels does not have large effect. However, we present that deformation of the imaginary potential has an important effect in explaining the elastic, inelastic and transfer reaction data simultaneously for this system.

  17. Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively.

    PubMed

    Popa, Marcel Mirel; Georgescu, Emilian; Caira, Mino R; Georgescu, Florentina; Draghici, Constantin; Stan, Raluca; Deleanu, Calin; Dumitrascu, Florea

    2015-01-01

    The three possible structural isomers of 4-(pyridyl)pyrimidine were employed for the synthesis of new pyrrolo[1,2-c]pyrimidines and new indolizines, by 1,3-dipolar cycloaddition reaction of their corresponding N-ylides generated in situ from their corresponding cycloimmonium bromides. In the case of 4-(3-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine the quaternization reactions occur as expected at the pyridine nitrogen atom leading to pyridinium bromides and consequently to new indolizines via the corresponding pyridinium N-ylides. However, in the case of 4-(2-pyridyl)pyrimidine the steric hindrance directs the reaction to the pyrimidinium N-ylides and, subsequently, to the formation of the pyrrolo[1,2-c]pyrimidines. The new pyrrolo[1,2-c]pyrimidines and the new indolizines were structurally characterized through NMR spectroscopy. The X-ray structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported. PMID:26199663

  18. TERAHERTZ SPECTROSCOPY OF THE BENDING VIBRATIONS OF ACETYLENE {sup 12}C{sub 2}H{sub 2}

    SciTech Connect

    Yu Shanshan; Drouin, Brian J.; Pearson, John C.

    2009-11-01

    Twenty P-branch transitions of {sup 12}C{sub 2}H{sub 2} have been measured in the 0.8-1.6 THz region of its bending vibrational difference band. The accuracy of these measurements is estimated to be 100 kHz. The {sup 12}C{sub 2}H{sub 2} molecules were generated under room temperature by passing 150 mTorr H{sub 2}O vapor through calcium carbide (CaC{sub 2}) powder. The observed transitions were modeled together with prior far-infrared data involving the bending levels with SIGMA{sub t}V{sub t} (t = 4,5)<=2. Frequency predictions of {sup 12}C{sub 2}H{sub 2} in the terahertz region have been greatly improved by adding the first data of 'microwave' precision. The new measurements and predictions reported here will facilitate the analyses of astronomical observations by the high spectral resolution telescopes such as Herschel, SOFIA, and ALMA.

  19. Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively

    PubMed Central

    Georgescu, Emilian; Georgescu, Florentina; Draghici, Constantin; Stan, Raluca; Deleanu, Calin; Dumitrascu, Florea

    2015-01-01

    Summary The three possible structural isomers of 4-(pyridyl)pyrimidine were employed for the synthesis of new pyrrolo[1,2-c]pyrimidines and new indolizines, by 1,3-dipolar cycloaddition reaction of their corresponding N-ylides generated in situ from their corresponding cycloimmonium bromides. In the case of 4-(3-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine the quaternization reactions occur as expected at the pyridine nitrogen atom leading to pyridinium bromides and consequently to new indolizines via the corresponding pyridinium N-ylides. However, in the case of 4-(2-pyridyl)pyrimidine the steric hindrance directs the reaction to the pyrimidinium N-ylides and, subsequently, to the formation of the pyrrolo[1,2-c]pyrimidines. The new pyrrolo[1,2-c]pyrimidines and the new indolizines were structurally characterized through NMR spectroscopy. The X-ray structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported. PMID:26199663

  20. Asymptotic normalization coefficients of resonant and bound states from the phase shifts for α α and α 12C scattering

    NASA Astrophysics Data System (ADS)

    Orlov, Yu. V.; Irgaziev, B. F.; Nikitina, L. I.

    2016-01-01

    Recently we have published a paper [Irgaziev, Phys. Rev. C 91, 024002 (2015), 10.1103/PhysRevC.91.024002] where the S -matrix pole method (SMP), which is only valid for resonances, has been developed to derive an explicit expression for the asymptotic normalization coefficient (ANC) and is applied to the low-energy resonant states of nucleon +α and α +12C systems. The SMP results are compared with the effective-range expansion method (EFE) results. In the present paper the SMP and EFE plus the Padé approximation are applied to study the excited 2+ resonant states of 9Be. A contradiction is found between descriptions of the experimental phase shift data for α α scattering and of the 9Be resonant energy for 2+ state. Using the EFE method, we also calculate the ANC for the 9Be ground 0+ state with a very small width. This ANC agrees well with the value calculated using the known analytical expression for narrow resonances. In addition, for the α +12C states 1- and 3- the SMP results are compared with the Padé approximation results. We find that the Padé approximation improves a resonance width description compared with the EFE results. The EFE method is also used to calculate the ANCs for the bound 0mml:mprescripts>O ground 0+ state and for the excited 1- and 2+ levels, which are situated near the threshold of α +12C channel.

  1. Measurement of elastic 12C+alpha scattering: details of the experiment, analysis, and discussion of phase shifts

    SciTech Connect

    Couture, Aaron Joseph; Detwiler, Rebecca; Gorres, Joachim; Stech, Edward J; Ugalde, Claudio; Wiescher, Michael C F; Heil, Michael; Kappeler, Franz; Azuma, Richard E; Buchmann, Lothar

    2009-01-01

    Recent global analyses of {sup 12}C({alpha},{gamma}){sup 16}O have incorporated both elastic-scallering and {beta}-decay data in addition to direct measurements. In that context, it has been shown that an improvement in the available elastic-scallering data could help determine the contribution of the two subthreshold states, 6.92(2{sup +}) and 7.12(1{sup -}) MeV, and with excellent statistics could restrict resonance parameters above the threshold. To this end angular distributions of {sup 12}C({alpha}, {alpha}){sup 12}C in the {alpha}-energy range of 2.6-8.2 MeV, at angles from 24 to 166 have been measured at the University of Notre Dame using an array of 32 silicon detectors. Details of the experiment are reported. In the present analysis, the phase shifts have been determined from our previously reported R-matrix fit to these data. The uncertainties in the R-matrix phase shifts ({ell} = 0...6) are derived by a new Monte Carlo analysis technique as described in the article. We provide these phase shifts here for general use, in particular for the improved analysis and extrapolation of the {alpha} radiative capture to low energies.

  2. Construction of a chimeric lysin Ply187N-V12C with extended lytic activity against staphylococci and streptococci

    PubMed Central

    Dong, Qiuhua; Wang, Jing; Yang, Hang; Wei, Cuihua; Yu, Junping; Zhang, Yun; Huang, Yanling; Zhang, Xian-En; Wei, Hongping

    2015-01-01

    Developing chimeric lysins with a wide lytic spectrum would be important for treating some infections caused by multiple pathogenic bacteria. In the present work, a novel chimeric lysin (Ply187N-V12C) was constructed by fusing the catalytic domain (Ply187N) of the bacteriophage lysin Ply187 with the cell binding domain (146-314aa, V12C) of the lysin PlyV12. The results showed that the chimeric lysin Ply187N-V12C had not only lytic activity similar to Ply187N against staphylococcal strains but also extended its lytic activity to streptococci and enterococci, such as Streptococcus dysgalactiae, Streptococcus agalactiae, Streptococcus pyogenes, Enterococcus faecium and Enterococcus faecalis, which Ply187N could not lyse. Our work demonstrated that generating novel chimeric lysins with an extended lytic spectrum was feasible through fusing a catalytic domain with a cell-binding domain from lysins with lytic spectra across multiple genera. PMID:25219798

  3. Comet nucleus sample return mission

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.

  4. Theoretical antideuteron-nucleus absorptive cross sections

    NASA Technical Reports Server (NTRS)

    Buck, W. W.; Norbury, J. W.; Townsend, L. W.; Wilson, J. W.

    1993-01-01

    Antideuteron-nucleus absorptive cross sections for intermediate to high energies are calculated using an ion-ion optical model. Good agreement with experiment (within 15 percent) is obtained in this same model for (bar p)-nucleus cross sections at laboratory energies up to 15 GeV. We describe a technique for estimating antinucleus-nucleus cross sections from NN data and suggest that further cosmic ray studies to search for antideuterons and other antinuclei be undertaken.

  5. Carbon Isotope Fractionation Between CO Gas and CO Ice with Implications for 12C/13C of the Interstellar Medium and the Early Solar System

    NASA Astrophysics Data System (ADS)

    Young, E. D.; Schauble, E. A.

    2011-03-01

    A model for carbon-isotope fractionation between CO ice and gas is presented. The model includes a self-consistent portrayal of the kinetics of partitioning of 12C and 13C between CO ice and gas. Ice-gas carbon exchange may be a primary control for 12C/13C.

  6. Study of 16O(12C,α20Ne)α for the investigation of carbon-carbon fusion reaction via the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Rapisarda, G. G.; Spitaleri, C.; Bordeanu, C.; Hons, Z.; Kiss, G. G.; La Cognata, M.; Mrazek, J.; Nita, C.; Pantelica, D.; Petrascu, H.; Pizzone, R. G.; Romano, S.; Szücs, T.; Trache, L.; Tumino, A.; Velisa, G.

    2016-04-01

    Carbon-carbon fusion reaction represents a nuclear process of great interest in astrophysics, since the carbon burning is connected with the third phase of massive stars (M > 8 M⊙) evolution. In spite of several experimental works, carbon-carbon cross section has been measured at energy still above the Gamow window moreover data at low energy present big uncertainty. In this paper we report the results about the study of the 16O(12C,α 20Ne)α reaction as a possible three-body process to investigate 12C(12C,α)20Ne at astrophysical energy via Trojan Horse Method (THM). This study represents the first step of a program of experiments aimed to measure the 12C+12C cross section at astrophysical energy using the THM.

  7. Measurement of the sup 12 C( p ,. pi. sup 0 ) sup 13 N reaction by recoil detection

    SciTech Connect

    Homolka, J.; Schott, W.; Wagner, W.; Wilhelm, W. ); Saber, M.; Segel, R.E. ); Bent, R.D.; Fatyga, M.; Pollock, R.E. ); Kienle, P. ); Rehm, K.E. )

    1992-03-01

    Differential cross sections for the neutral pion production reaction {sup 12}C({ital p},{pi}{sup 0}){sup 13}N{sub g.s.} have been measured at 153.5, 166.1, 186.0, and 204.0 MeV bombarding energy using recoil detection. The shape of the angular distribution agrees well with that of the mirror reaction {sup 12}C({ital p},{pi}{sup +}){sup 13}C{sub g.s.}. Isospin invariance predicts for the ratio of the cross sections {sigma}({ital p},{pi}{sup +})/{sigma}({ital p},{pi}{sup 0})=2. At 153.5, 166.1, and 186.0, MeV, where ({ital p},{pi}{sup +}) cross sections have been reported previously by other groups at the same reduced pion momentum {eta}={ital p}{sub {pi}}/{ital m}{sub {pi}}{ital c}=0.34,0.55,0.78, the ratio of the total cross sections is 2.02{plus minus}0.14, 3.14{plus minus}0.12, and 2.12{plus minus}0.16, respectively. The ({ital p},{pi}{sup 0}) cross sections at 166 MeV is therefore 1.57{plus minus}0.06 times larger than expected. For {ital T}{sub {ital p}}{lt}160 MeV, the experimental cross sections are larger than predicted by a phase space and Coulomb barrier penetration calculation that fits the higher-energy data. Differential cross sections were also obtained for the {sup 12}C({ital p},{pi}{sup {minus}}){sup 13}O reaction, and upper limits set for differential cross sections for radiative capture to the ground state of {sup 13}N.

  8. Air-broadened line parameters with temperature dependence for 12C16O, 13C16O, and 12C18O at 2.3 μm

    NASA Astrophysics Data System (ADS)

    Smith, M. H.; Malathy Devi, V.; Benner, D.; Mantz, A. W.; Sung, K.; Brown, L. R.

    2012-12-01

    To improve the spectroscopic database for remote sensing of tropospheric CO, we have recorded more than 50 high resolution (0.005 cm-1) spectra of CO and two of its isotopologues (13CO and C18O) at temperatures between 150 and 298 K using a coolable absorption cell in the sample compartment of the Bruker IFS 125HR Fourier transform spectrometer at Jet Propulsion Laboratory. Air-broadened spectra at total pressures up to 700 Torr were recorded for all three isotopologues, and self-broadened CO spectra were also recorded. Line parameters were determined by broad-band constrained multispectrum least-squares fitting of 16 or more spectra simultaneously. Parameters determined in the fits included Lorentz half-width coefficients, their temperature dependence exponents; pressure-induced line shift coefficients, their temperature dependences; and the off-diagonal relaxation matrix elements that characterize line mixing. Speed dependence parameters were also included to minimize the fit residuals. The individual line positions and intensities were constrained to their theoretical relationships in order to obtain the rovibrational (G, B, D, and H) and band intensity parameters, including Herman-Wallis coefficients, as has been done for CO2 previously. The air-broadening results for the 13C16O and 12C18O 2-0 bands are compared with each other and with those for the corresponding 12C16O band.

  9. Reaction mechanisms in {sup 24}Mg+{sup 12}C and {sup 32}S+{sup 24}Mg

    SciTech Connect

    Beck, C.; Sanchez i Zafra, A.; Papka, P.; Thummerer, S.; Azaiez, F.; Courtin, S.; Curien, D.; Dorvaux, O.; Lebhertz, D.; Nourreddine, A.; Rousseau, M.; Oertzen, W. von; Gebauer, B.; Kokalova, Tz.; Wheldon, C.; De Angelis, G.; Gadea, A.; Lenzi, S.; Napoli, D. R.; Szilner, S.

    2009-03-04

    The occurrence of 'exotic' shapes in light N = Z{alpha}-like nuclei is investigated for {sup 24}Mg+{sup 12}C and {sup 32}S+{sup 24}Mg. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures with low spin are presented. For both reactions, exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility of Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated {gamma}-decays studied. The analysis of the binary and ternary reaction channels is discussed.

  10. Detailed study and mean field interpretation of {sup 16}O+{sup 12}C elastic scattering at seven medium energies

    SciTech Connect

    Nicoli, M. P.; Haas, F.; Freeman, R. M.; Szilner, S.; Basrak, Z.; Morsad, A.; Satchler, G. R.; Brandan, M. E.

    2000-03-01

    Detailed measurements of the elastic scattering of {sup 16}O ions from {sup 12}C have been carried out at seven energies from 62 to 124 MeV, at center-of-mass angles from about 10 degree sign to about 145 degree sign . A coherent optical model analysis of these data has been performed using both the Woods-Saxon and the folding-model potentials. The extracted results are consistent with analyses of data at higher energies for this and similar light heavy-ion systems. Some model-independent spline forms for the real potentials were also investigated. (c) 2000 The American Physical Society.

  11. {sup 16}O resonances near 4α threshold through {sup 12}C({sup 6}Li,d) reaction

    SciTech Connect

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Faria, P. Neto de; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M.; Napoli, M. di; Ukita, G. M.

    2014-11-11

    Several narrow alpha resonant {sup 16}O states were detected through the {sup 12}C({sup 6}Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)

  12. Effective field theory of Bose-Einstein condensation of α clusters and Nambu-Goldstone-Higgs states in 12C

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.; Takahashi, J.; Yamanaka, Y.; Ohkubo, S.

    2016-07-01

    An effective field theory of α -cluster condensation is formulated as a spontaneously broken symmetry in quantum field theory to understand the raison d'être and the nature of the Hoyle and α -cluster states in 12C. The Nambu-Goldstone and Higgs mode operators in infinite systems are replaced with a pair of canonical operators whose Hamiltonian gives rise to discrete energy states in addition to the Bogoliubov-de Gennes excited states. The calculations reproduce well the experimental spectrum of the α -cluster states. The existence of the Nambu-Goldstone-Higgs states is demonstrated and crucial. The γ -decay transitions are also obtained.

  13. Analyzing powers for {sup 6}{rvec L}i+{sup 12}C scattering at 30 and 50 MeV

    SciTech Connect

    Kerr, P.L.; Reber, E.L.; Green, P.V.; Kemper, K.W.; Mendez, A.J.; Mohajeri, K.; Myers, E.G.; Schmidt, B.G.; Hnizdo, V.

    1995-07-15

    Comparison between elastic analyzing powers at 30 and 50 MeV show no decrease in their magnitude at the higher energy. A combined optical model analysis of both energies shows T{sub 21} to arise from the tensor interaction, T{sub 20} to be an interference between tensor and J dependent interactions, and iT{sub 11} to be the most complicated, arising from an explicit spin-orbit, tensor, and J dependent interactions. The inelastic {sup 12}C vector analyzing powers require an explicit spin-orbit interaction to reproduce the magnitude of the oscillations.

  14. Binary channels of the {sup 19}F-on-{sup 12}C reaction at 92 MeV

    SciTech Connect

    Aissaoui, N.; Haas, F.; Freeman, R.M.; Beck, C.; Morsad, A.; Djerroud, B.; Caplar, R.; Hachem, A.

    1997-01-01

    Binary-reaction channels of {sup 19}F+{sup 12}C have been studied at E{sub lab}({sup 19}F)=92 MeV using kinematic coincidence techniques. The results are discussed in the light of previous inclusive measurements performed at the same incident energy and for which the occurrence of an important incomplete fusion mechanism after projectile breakup was proposed. Evidence for strong damped binary, especially quasisymmetric, decay processes is found. {copyright} {ital 1997} {ital The American Physical Society}

  15. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    NASA Astrophysics Data System (ADS)

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

  16. Catalytic Sulfur-Enabled Dehydrobicyclization of 1,6-Enynes toward Arylated Indeno[1,2-c]thiophenes.

    PubMed

    Wu, Ya-Nan; Fu, Rong; Wang, Nan-Nan; Hao, Wen-Juan; Li, Guigen; Tu, Shu-Jiang; Jiang, Bo

    2016-06-01

    A new copper-catalyzed sulfur-enabled dehydrobicyclization of 1,6-enynes using potassium sulfide as a sulfurating reagent has been established, providing a straightforward access toward arylated indeno[1,2-c]thiophenes with moderate to good yields. This sulfur incorporation pathway involves Michael addition, 5-exo-dig/5-endo-trig bicyclization and dehydrogenation sequence, resulting in continuous multiple bond-forming events including C-S and C-C bonds to rapidly construct functional organic molecules. PMID:27176454

  17. Comparative Study of {sup 6}He+{sup 12}C System by using Different Types of Nucleon Density Distributions

    SciTech Connect

    Kucuk, Y.; Boztosun, I.; Ibraheem, A.

    2008-11-11

    In this paper, we present the analysis of the {sup 6}He+{sup 12}C elastic scattering at 18.0 MeV within the framework of the double folding model. In order to make a comparative study, we have used four different types of nucleon density distributions for the ground state of the {sup 6}He in the microscopic potential calculations. We have observed that all these density distributions provide a consistent description of the elastic scattering angular distributions for this system.

  18. Actomyosin contractility rotates the cell nucleus

    PubMed Central

    Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G. V.

    2014-01-01

    The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells. PMID:24445418

  19. Astrophysical S factor of the 12C(α ,γ )6O reaction calculated with reduced R -matrix theory

    NASA Astrophysics Data System (ADS)

    An, Zhen-Dong; Chen, Zhen-Peng; Ma, Yu-Gang; Yu, Jian-Kai; Sun, Ye-Ying; Fan, Gong-Tao; Li, Yong-Jiang; Xu, Hang-Hua; Huang, Bo-Song; Wang, Kan

    2015-10-01

    Determination of the accurate astrophysical S factor of 12C(α ,γ )16O reaction has been regarded as the holy grail of nuclear astrophysics for decades. In current stellar models, a knowledge of that value to better than 10% is desirable. Due to the practical issues, tremendous experimental and theoretical efforts over nearly 50 years are not able to reach this goal, and the published values contradicted with each other strongly and their uncertainties are two times larger than the required precision. To this end we have developed a reduced R -matrix theory based on the classical R -matrix theory of Lane and Thomas, which treats primary transitions to the ground state and four bound states as the independent reaction channels in the channel spin representation. With the coordination of covariance statistics and error-propagation theory, a global fitting for almost all available experimental data of 16O system has been multi-iteratively analyzed by our powerful code. A reliable, accurate, and self-consistent astrophysical S factor of 12C(α ,γ )16O was obtained with a recommended value Stot(0.3 MeV ) =162.7 ±7.3 keV b (4.5%) which could meet the required precision.

  20. Modelling the 13C and 12C isotopes of inorganic and organic carbon in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Gustafsson, Erik; Mörth, Carl-Magnus; Humborg, Christoph; Gustafsson, Bo G.

    2015-08-01

    In this study, 12C and 13C contents of all carbon containing state variables (dissolved inorganic and organic carbon, detrital carbon, and the carbon content of autotrophs and heterotrophs) have for the first time been explicitly included in a coupled physical-biogeochemical Baltic Sea model. Different processes in the carbon cycling have distinct fractionation values, resulting in specific isotopic fingerprints. Thus, in addition to simulating concentrations of different tracers, our new model formulation improves the possibility to constrain the rates of processes such as CO2 assimilation, mineralization, and air-sea exchange. We demonstrate that phytoplankton production and respiration, and the related air-sea CO2 fluxes, are to a large degree controlling the isotopic composition of organic and inorganic carbon in the system. The isotopic composition is further, but to a lesser extent, influenced by river loads and deep water inflows as well as transformation of terrestrial organic carbon within the system. Changes in the isotopic composition over the 20th century have been dominated by two processes - the preferential release of 12C to the atmosphere in association with fossil fuel burning, and the eutrophication of the Baltic Sea related to increased nutrient loads under the second half of the century.

  1. Survival of orbiting in {sup 20}Ne (7-10 MeV/nucleon) + {sup 12}C reactions

    SciTech Connect

    Bhattacharya, C.; Dey, A.; Kundu, S.; Banerjee, K.; Bhattacharya, S.; Mukhopadhyay, S.; Gupta, D.; Bhattacharjee, T.; Banerjee, S.R.; Bhattacharyya, S.; Rana, T.; Basu, S.K.; Saha, R.; Bhattacharjee, S.; Krishan, K.; Mukherjee, A.; Bandopadhyay, D.; Beck, C.

    2005-08-01

    The inclusive energy distributions of fragments with Z {>=} 3 emitted from the bombardment of {sup 12}C by {sup 20}Ne beams with incident energies between 145 and 200 MeV have been measured in the angular range {theta}{sub lab}{approx}10 deg. -50 deg. Damped fragment yields in all cases have been found to be characteristic of emission from fully energy equilibrated composites; for B and C fragments, average Q values, , were independent of the center-of-mass emission angle ({theta}{sub c.m.}), and the angular distributions followed a {approx}1/sin{theta}{sub c.m.}-like variation, signifying long lifetimes of the emitting dinuclear systems. Estimates of total yields of these fragments have been found to be much larger than those predicted by the standard statistical model. This may be indicative of the survival of an orbiting-like process in the {sup 12}C+{sup 20}Ne system at these energies.

  2. The {sup 12}C({alpha}, {gamma}){sup 16}O E2 cross section at stellar energies

    SciTech Connect

    Descouvemont, P.; Dufour, M.

    2010-08-12

    The E2 component of the {sup 12}C({alpha}, {gamma}){sup 16}O cross section is investigated by a microscopic cluster model, and by R-matrix fits. The first approach provides S{sub E2}(300 keV){approx_equal}50 keV-b for ground-state transitions. In the R-matrix theory, we show that the background term plays a crucial role, and cannot be determined without ambiguity. Only an upper limit on the extrapolated S factor can be obtained [S{sub E2}(300 keV)<190 keV-b]. To constrain the R-matrix analysis, we use the GCM Asymptotic Normalization Constant (ANC) of the 2{sub 1}{sup +} level. This procedure strongly reduces the uncertainties on the R-matrix fit, and we end up with a recommended value of S{sub E2}(300 keV) =42{+-}2 keV-b. As ANC values derived from indirect methods are not consistent with the {sup 12}C({alpha}, {gamma}){sup 16}O cascade transitions to the 2{sub 1}{sup +} state, we suggest a remeasurement of this cross section.

  3. Effective source size, radial, angular and energy spread of therapeutic 11C positron emitter beams produced by 12C fragmentation

    NASA Astrophysics Data System (ADS)

    Lazzeroni, Marta; Brahme, Anders

    2014-02-01

    The use of positron emitter light ion beams in combination with PET (Positron Emission Tomography) and PET-CT (Computed Tomography) imaging could significantly improve treatment verification and dose delivery imaging during radiation therapy. The present study is dedicated to the analysis of the beam quality in terms of the effective source size, as well as radial, angular and energy spread of the 11C ion beam produced by projectile fragmentation of a primary point monodirectional and monoenergetic 12C ion beam in a dedicated range shifter of different materials. This study was performed combining analytical methods describing the transport of particles in matter and the Monte Carlo code SHIELD-HIT+. A high brilliance and production yield of 11C fragments with a small effective source size and emittance is best achieved with a decelerator made of two media: a first liquid hydrogen section of about 20 cm followed by a hydrogen rich section of variable length. The calculated intensity of the produced 11C ion beam ranges from about 5% to 8% of the primary 12C beam intensity depending on the exit energy and the acceptance of the beam transport system. The angular spread is lower than 1 degree for all the materials studied, but the brilliance of the beam is the highest with the proposed mixed decelerator.

  4. Particle gamma correlations in 12C measured with the CsI(Tl) based detector array CHIMERA

    NASA Astrophysics Data System (ADS)

    Cardella, G.; Acosta, L.; Amorini, F.; Auditore, L.; Berceanu, I.; Castoldi, A.; De Filippo, E.; Dell`Aquila, D.; Francalanza, L.; Gnoffo, B.; Guazzoni, C.; Lanzalone, G.; Lombardo, I.; Minniti, T.; Morgana, E.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Pop, A.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2015-11-01

    The gamma decay of the first excited 4.44 MeV 2+level of 12C, populated by inelastic scattering of proton and 16O beams at various energies was studied in order to test γ-ray detection efficiency and the quality of angular distribution information given by the CsI(Tl) detectors of the 4π CHIMERA array. The γ-decay was measured in coincidence with ejectile scattered particles in an approximately 4π geometry allowing to extract the angular distribution in the reference frame of recoiling 12C target. The typical sin2 (2θ) behavior of angular distribution was observed in the case of 16O beam. Besides that, for the proton beam, in order to explain the observed distribution, the addition of an incoherent flat contribution was required. This latter is the effect of proton spin flip events allowing the population of M=±1 magnetic substates, that is not possible in reactions induced by 16O beam. A comparison with previously collected data, obtained measuring only in and out of plane proton-γ-ray coincidences, confirms the good quality of the angular distribution information given by the apparatus. Possible applications with radioactive beams are outlined.

  5. A capillary absorption spectrometer for stable carbon isotope ratio (13C/12C) analysis in very small samples

    NASA Astrophysics Data System (ADS)

    Kelly, J. F.; Sams, R. L.; Blake, T. A.; Newburn, M.; Moran, J.; Alexander, M. L.; Kreuzer, H.

    2012-02-01

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO2 samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO2 near 2307 cm-1 (4.34 μm). This initial CAS system can achieve relative isotopic precision of about 10 ppm 13C, or ˜1‰ (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO2 concentrations ˜400-750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to ˜2 Torr. Overall 13C/12C ratios can be calibrated to ˜2‰ accuracy with diluted CO2 standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1000 scans are co-added in ˜10 s. The CAS is meant to work directly with converted CO2 samples from a laser ablation-catalytic combustion micro-sampler to provide 13C/12C ratios of small biological isolates currently operating with spatial resolutions ˜50 μm.

  6. Integral measurement of the 12C(n, p)12B reaction up to 10 GeV

    NASA Astrophysics Data System (ADS)

    Žugec, P.; Colonna, N.; Bosnar, D.; Ventura, A.; Mengoni, A.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Duran, I.; Eleftheriadis, C.; Ferrari, A.; Finocchiaro, P.; 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.; Heinitz, S.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Karadimos, D.; Kivel, N.; Kokkoris, M.; Krtička, M.; Kroll, J.; Langer, C.; Lederer, C.; Leeb, H.; Leong, L. S.; Lo Meo, S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mendoza, E.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondalaers, W.; Musumarra, A.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A.; Praena, J.; Quesada, J.; Rauscher, T.; Reifarth, R.; Riego, A.; Roman, F.; Rubbia, C.; Sarmento, R.; Saxena, A.; 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.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.

    2016-04-01

    The integral measurement of the 12C(n, p)12B reaction was performed at the neutron time-of-flight facility n_TOF at CERN. The total number of 12B nuclei produced per neutron pulse of the n_TOF beam was determined using the activation technique in combination with a time-of-flight technique. The cross section is integrated over the n_TOF neutron energy spectrum from reaction threshold at 13.6MeV to 10GeV. Having been measured up to 1GeV on basis of the 235U(n, f ) reaction, the neutron energy spectrum above 200MeV has been re-evaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1GeV up to 10GeV. The experimental results related to the 12C(n, p)12B reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which mostly underestimate the 12B production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters.

  7. Analyzing powers for ^12C(^6Li,d) at E(^6Li) = 50 MeV

    NASA Astrophysics Data System (ADS)

    Drummer, T. L.; Bartosz, E. E.; Cathers, P. D.; Fauerbach, M.; Kemper, K. W.; Myers, E. G.; Rusek, K.

    1998-04-01

    A complete set of analyzing powers (iT_11, T_20, T_21, T_22 and ^TT_20) have been measured for the stripping reaction ^12C(^6Li,d) at E(^6Li) = 50 MeV. At this energy, only states that have ``well known'' α + ^12C structures are strongly populated. Both DWBA and very detailed coupled reaction channels calculations have been performed to study the sensitivity of the extracted α spectroscopic factors to assumptions made regarding the coupling between states in the different projectile, target and ejectile inelastic channels. The coupled channels calculations were performed using the computer code FRESCO written by Ian Thompson running on Pentium PCs using the operating system Linux. The vector analyzing powers are almost totally determined by the deuteron spin-orbit potentials. DWBA and CCBA calculations both describe the data quite well. The extracted ground state spectroscopic factors are the same within 20% when previous data from 34 MeV(Data taken with C.R. Brune, H.J. Karwowski, E.J. Ludwig, A.J. Mendez, K.D. Veal and B. Kozlowska, University of North Carolina.) are analyzied with the present data. Supported by the National Science Foundation, the State of Florida and the State Committee for Scientific Research (KBN) of Poland.

  8. Measurements and Modeling of 16O12C17O Spectroscopic Parameters at 2 μm

    NASA Astrophysics Data System (ADS)

    Jacquemart, David; Sung, Keeyoon; Brown, Linda; Coleman, Max; Mantz, Arlan; Smith, Mary Ann H.

    2014-06-01

    Nearly 1000 line intensities of 16O12C17O between 4604 and 5126 wn were measured using an isotopically-enriched mixture sample having 40 % (determined by mass spectrometry). Spectra were recorded at 0.0056 wn resolution with a Fourier transform spectrometer (Bruker IFS-125HR at JPL) configured to a Herriott cell with a 20.946 m absorption path. Since collisional narrowing effects were observed, the Rautian profile was systematically applied (instead of the Voigt profile) using a multispectrum retrieval procedure. Transition dipole moments and Herman-Wallis factors were derived for 15 bands, and a global comparison with theoretical calculations and predictions was obtained. Accuracies for the line intensities ranged between 2 - 3 % for strong bands and 6 - 30 % for weak bands. Retrieved line positions were calibrated using CO, HCl and some well-known 16O12C16O transitions. For both measured and calculated line positions, the accuracies fell between 0.1 - 1×10-3 wn. Self-broadening was also obtained for a few bands. Complete line lists were generated to support atmospheric remote sensing of the Earth (e.g., OCO-2 mission), Mars and Venus. Research described in this paper was performed at Connecticut College, the Jet Propulsion Laboratory, and California Institute of Technology, and NASA Langley Research Center, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  9. Direct measurement of {sup 4}He({sup 12}C, {sup 16}O)gamma reaction at KUTL

    SciTech Connect

    Fujita, K.; Sagara, K.; Teranishi, T.; Goto, T.; Iwabuchi, R.; Matsuda, S.; Nakano, K.; Oba, N.; Taniguchi, M.; Yamaguchi, H.

    2010-06-01

    A {sup 12}C+{sup 4}He->{sup 16}O+gamma is regarded as the very important reaction to know the evolution of heavy stars. The cross section is, however, still unknown in spite of more than 40 years experiment in the world because of an existence of a resonance state of {sup 16}O at sub-threshold region. A cross section measurement with the direct detection of the produced {sup 16}O from E{sub cm} = 2.4 downto 0.7 MeV have been planned at Kyushu University Tandem Laboratory(KUTL). Detection of the {sup 16}O is the most possible method at low energy, since a detection efficiency of the {sup 16}O is very high.The new windowless blow-in gas target was developed to achieve the pressure of 24 Torr. Many movable slit were installed in a recoil mass separator, so that the backgrounds generated by the {sup 12}C beam was eliminated effectively. The results of recent experiments at E{sub cm} = 2.4 and 1.5 MeV are reported.

  10. A comparative study on radioprotective effect of N-acetylcysteine against 12C6+ ion versus X-rays

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Zhang, Hong; Zhang, Luwei

    Purpose: The aim of this study was to evaluate the different protective efficacy of N-acetylcysteine (NAC, 200 mg/kg dose) against 12C6+ ion (4 Gy) and X-rays (4 Gy) - induced damage in vivo model. Method: Kung-Ming female mice were divided into six groups, each composed of twelve animals: control group, two irradiation groups, and two NAC-treated groups, as well as NAC alone-treated group. An acute study was carried out to determine alterations in the oxidative stress (malondialdehyde level) using with colorimetric method and cell apoptosis measuring by flow cytometry as well as DNA-single strand break analyzing by comet assay at 2h after irradiation in mouse liver. Results: Compared with respective irradiation group, NAC can significantly ameliorate injury induced by two types of ionizing irradiation, which marked by the decrease of malondialdehyde level, and the reduction of apoptosis cells percentage and DNA damage. But the greater efficacy of NAC was prominently observed to inhibit the damage induced by X-rays, suggesting that NAC-mediated protective effect is more advisable to X-rays than 12C6+ ion irradiation. Moreover, NAC treatment alone did not result in any damage as compared to the control group. Conclusion: NAC may merit development as a potential radioprotective agent. Furthermore, NAC might exert its best effort to respond X rays-caused damage.

  11. Elastic deuteron scattering on {sup 12}C and {sup 16}O nuclei in the alpha-cluster model

    SciTech Connect

    Berezhnoy, Yu. A.; Mikhailyuk, V. P.; Pilipenko, V. V. Fedorchenko, D. V.

    2013-07-15

    On the basis of the dispersive alpha-cluster model for target nuclei and the theory of multiple diffractive scattering, differential cross sections and analyzing powers for the elastic scattering of 400 and 700-MeV deuterons on {sup 12}C and {sup 16}O target nuclei were calculated in the pointlike-deuteron approximation. In these calculations, the amplitude for incident-deuteron scattering on nuclei was constructed with the aid of amplitudes for d{alpha} scattering that were obtained from a fit to data on d{sup 16}O scattering. The same features were calculated on the basis of the diffraction approximation with allowance for the internal deuteron structure by using the amplitudes obtained earlier for nucleon scattering on {sup 12}C and {sup 16}O nuclei within the same dispersive alpha-clustermodel. The latter made it possible to perform calculations without employing adjustable parameters. The observables calculated on the basis of either approach agree with available experimental data.

  12. Use of laser spectroscopy to measure the 13C/12C and 18O/16O compositions of carbonate minerals.

    PubMed

    Barker, Shaun L L; Dipple, Gregory M; Dong, Feng; Baer, Douglas S

    2011-03-15

    The stable carbon and oxygen isotope compositions of carbonate minerals are utilized throughout the earth and environmental sciences for various purposes. Here, we demonstrate the first application of a prototype instrument, based on off-axis integrated cavity output laser spectroscopy, to measure the carbon and oxygen isotope composition of CO(2) gas evolved from the acidification of carbonate minerals. The carbon and oxygen isotope ratios were recorded from absorption spectra of (12)C(16)O(16)O, (13)C(16)O(16)O, and (12)C(16)O(18)O in the near-infrared wavelength region. The instrument was calibrated using CaCO(3) minerals with known δ(13)C(VPDB) and δ(18)O(VSMOW) values, which had been previously calibrated by isotope ratio mass spectrometry relative to the international isotopic standards NBS 18 and NBS 19. Individual analyses are demonstrated to have internal precision (1 SE) of better than 0.15‰ for δ(13)C and 0.6‰ for δ(18)O. Analysis of four carbonate standards of known isotopic composition over 2 months, determined using the original instrumental calibration, indicates that analyses are accurate to better than 0.5‰ for both δ(13)C and δ(18)O without application of standard-sample-standard corrections. PMID:21341717

  13. Theoretical investigation of stabilities and optical properties of Si{sub 12}C{sub 12} clusters

    SciTech Connect

    Duan, Xiaofeng F.; Burggraf, Larry W.

    2015-01-21

    By sorting through hundreds of globally stable Si{sub 12}C{sub 12} isomers using a potential surface search and using simulated annealing, we have identified low-energy structures. Unlike isomers knit together by Si–C bonds, the lowest energy isomers have segregated carbon and silicon regions that maximize stronger C–C bonding. Positing that charge separation between the carbon and silicon regions would produce interesting optical absorption in these cluster molecules, we used time-dependent density functional theory to compare the calculated optical properties of four isomers representing structural classes having different types of silicon and carbon segregation regions. Absorptions involving charge transfer between segregated carbon and silicon regions produce lower excitation energies than do structures having alternating Si–C bonding for which frontier orbital charge transfer is exclusively from separated carbon atoms to silicon atoms. The most stable Si{sub 12}C{sub 12} isomer at temperatures below 1100 K is unique as regards its high symmetry and large optical oscillator strength in the visible blue. Its high-energy and low-energy visible transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer.

  14. Investigation of the mixed-symmetric one-quadrupole phonon 2+ 1,ms state of the heavy nucleus 204Hg

    NASA Astrophysics Data System (ADS)

    Stegmann, R.; Stahl, C.; Rainovski, G.; Pietralla, N.; Möller, T.; Lettmann, M.; Janssens, R. V. F.; Carpenter, M.; Zhu, S.

    2016-06-01

    Low-energy quadrupole-collective excitations of isovector character, the so-called states with proton-neutron mixed-symmetric character (MSS), have been investigated in 204Hg which is the sole stable nucleus in the straight vicinity of 208Pb exhibiting a 2π — 2ν structure. A 12C(204Hg,204Hg*)12C projectile Coulomb-excitation experiment at 890MeV was performed at Argonne National Laboratory using the ATLAS accelerator. γ-rays originating from the decay of the excited states of 204Hg were detected using the GAMMASPHERE spectrometer. The measured Coulomb-excitation yields provide the B(M1) and the B(E2) strength distributions which unambiguously reveal the 23 + state at 1948 keV as the one-phonon MSS of 204Hg.

  15. The retrotrapezoid nucleus and breathing.

    PubMed

    Guyenet, Patrice G; Stornetta, Ruth L; Abbott, Stephen B G; Depuy, Seth D; Kanbar, Roy

    2012-01-01

    The retrotrapezoid nucleus (RTN) is located in the rostral medulla oblongata close to the ventral surface and consists of a bilateral cluster of glutamatergic neurons that are non-aminergic and express homeodomain transcription factor Phox2b throughout life. These neurons respond vigorously to increases in local pCO(2) via cell-autonomous and paracrine (glial) mechanisms and receive additional chemosensory information from the carotid bodies. RTN neurons exclusively innervate the regions of the brainstem that contain the respiratory pattern generator (RPG). Lesion or inhibition of RTN neurons largely attenuates the respiratory chemoreflex of adult rats whereas their activation increases respiratory rate, inspiratory amplitude and active expiration. Phox2b mutations that cause congenital central hypoventilation syndrome in humans prevent the development of RTN neurons in mice. Selective deletion of the RTN Phox2b-VGLUT2 neurons by genetic means in mice eliminates the respiratory chemoreflex in neonates.In short, RTN Phox2b-VGLUT2 neurons are a major nodal point of the CNS network that regulates pCO(2) via breathing and these cells are probable central chemoreceptors. PMID:23080151

  16. The multifunctional lateral geniculate nucleus.

    PubMed

    Weyand, Theodore G

    2016-02-01

    Providing the critical link between the retina and visual cortex, the well-studied lateral geniculate nucleus (LGN) has stood out as a structure in search of a function exceeding the mundane 'relay'. For many mammals, it is structurally impressive: Exquisite lamination, sophisticated microcircuits, and blending of multiple inputs suggest some fundamental transform. This impression is bolstered by the fact that numerically, the retina accounts for a small fraction of its input. Despite such promise, the extent to which an LGN neuron separates itself from its retinal brethren has proven difficult to appreciate. Here, I argue that whereas retinogeniculate coupling is strong, what occurs in the LGN is judicious pruning of a retinal drive by nonretinal inputs. These nonretinal inputs reshape a receptive field that under the right conditions departs significantly from its retinal drive, even if transiently. I first review design features of the LGN and follow with evidence for 10 putative functions. Only two of these tend to surface in textbooks: parsing retinal axons by eye and functional group and gating by state. Among the remaining putative functions, implementation of the principle of graceful degradation and temporal decorrelation are at least as interesting but much less promoted. The retina solves formidable problems imposed by physics to yield multiple efficient and sensitive representations of the world. The LGN applies context, increasing content, and gates several of these representations. Even if the basic concentric receptive field remains, information transmitted for each LGN spike relative to each retinal spike is measurably increased. PMID:26479339

  17. Music and the nucleus accumbens.

    PubMed

    Mavridis, Ioannis N

    2015-03-01

    Music is a universal feature of human societies over time, mainly because it allows expression and regulation of strong emotions, thus influencing moods and evoking pleasure. The nucleus accumbens (NA), the most important pleasure center of the human brain (dominates the reward system), is the 'king of neurosciences' and dopamine (DA) can be rightfully considered as its 'crown' due to the fundamental role that this neurotransmitter plays in the brain's reward system. Purpose of this article was to review the existing literature regarding the relation between music and the NA. Studies have shown that reward value for music can be coded by activity levels in the NA, whose functional connectivity with auditory and frontal areas increases as a function of increasing musical reward. Listening to music strongly modulates activity in a network of mesolimbic structures involved in reward processing including the NA. The functional connectivity between brain regions mediating reward, autonomic and cognitive processing provides insight into understanding why listening to music is one of the most rewarding and pleasurable human experiences. Musical stimuli can significantly increase extracellular DA levels in the NA. NA DA and serotonin were found significantly higher in animals exposed to music. Finally, passive listening to unfamiliar although liked music showed activations in the NA. PMID:25102783

  18. Complete and incomplete fusion and emission of preequilibrium nucleons in the interaction of [sup 12]C with [sup 197]Au below 10 MeV/nucleon

    SciTech Connect

    Vergani, P.; Gadioli, E.; Vaciago, E.; Fabrici, E.; Gadioli Erba, E.; Galmarini, M. ); Ciavola, G.; Marchetta, C. )

    1993-10-01

    The excitation functions for production of nineteen isotopes of At, Po, Bi, Pb, and Tl in the interaction of [sup 12]C with [sup 197]Au between 57 and 97 MeV incident energy have been measured with the activation technique. The analysis of these data allows one to estimate the cross sections for complete fusion of [sup 12]C and incomplete fusion of [sup 8]Be and [alpha] fragments with gold, and shows the presence of preequilibrium emissions at incident energies only slightly higher than the Coulomb barrier acting between [sup 12]C and [sup 197]Au.

  19. Nucleus accumbens stimulation in pathological obesity.

    PubMed

    Harat, Marek; Rudaś, Marcin; Zieliński, Piotr; Birska, Julita; Sokal, Paweł

    2016-01-01

    One of the potential treatment methods of obesity is deep brain stimulation (DBS) of nucleus accumbens. We describe the case of 19 years old woman with hypothalamic obesity. She weighted 151.4 kg before DBS and the non-surgical methods proved to be inefficient. She was treated with implantation of DBS electrode to nucleus accumbens bilaterally. Results were measured with body mass index and neuropsychological tests. Follow-up was 14 months. Fourteen months after surgery weight was 138 kg, BMI was 48.3. Neuropsychological test results were intact. The presented case supports the thesis of treatment of obesity with nucleus accumbens stimulation. PMID:27154450

  20. Microscopic study of neutron elastic scattering from {sup 12}C, {sup 40}Ca, and {sup 208}Pb at intermediate energies

    SciTech Connect

    Alvi, M. A.; Arafah, M. R.; Madani, J. H.; Ahmad, I.

    2009-02-15

    Recent neutron elastic scattering differential cross section data for {sup 12}C, {sup 40}Ca, and {sup 208}Pb at several energies from 65 to 225 MeV have been analyzed using Glauber multiple scattering model, suitably modified to enlarge angular range of validity. The center of mass and Pauli pair correlations have been considered. The effect of the phase variation of the NN scattering amplitude on the calculated cross sections has been studied. A medium modification of the 'elementary' NN interaction is also considered. The neutron differential cross sections have been calculated using the phenomenological and the recently proposed semiphenomenological neutron and proton target densities so as to check the validity of the semiphenomenological density model. We found that our method of analysis gives a very good description of the experimental data.

  1. CO2 pressure broadening and shift coefficients for the 2-0 band of 12C16O

    NASA Astrophysics Data System (ADS)

    Hashemi, R.; Predoi-Cross, A.; Dudaryonok, A. S.; Lavrentieva, N. N.; Vandaele, A. C.; Vander Auwera, J.

    2016-08-01

    Fourier transform absorption spectra of the 2-0 band of 12C16O mixed with CO2 have been recorded at total pressures from 156 to 1212 hPa and at 4 different temperatures between 240 K and 283 K. CO2 pressure-induced line broadening and line shift coefficients, and the temperature dependence of the former have been measured including line mixing using a multi-spectrum non-linear least squares fitting technique. Different line shape models have been considered to take into account the Dicke narrowing or speed dependence effects. Measured line-shape parameters were compared with theoretical values, calculated for individual temperatures using a semi-empirical method and the Exponential Power Gap (EPG) law.

  2. Improved determination of the astrophysical S(0) factor of the {sup 15}N(p,{alpha}){sup 12}C reaction

    SciTech Connect

    La Cognata, M.; Spitaleri, C.; Goldberg, V. Z.; Mukhamedzhanov, A. M.; Tribble, R. E.

    2009-07-15

    We present new improved R matrix fits of direct data and indirect Trojan Horse data for the {sup 15}N(p,{alpha}){sup 12}C reaction and provide a more accurate recommended value of S(0)=73.0{+-}5.0 MeV b from direct Redder data [A. Redder et al., Z. Phys. A 305, 325 (1982)] and S(0)=70.0{+-}13.5 MeV b from the Trojan Horse data [M. La Cognata et al., Phys. Rev. C 76, 065804 (2007)]. We also analyze a recent fit by Barker [F. C. Barker, Phys. Rev. C 78, 044611 (2008)] and demonstrate that when all the uncertainties are taken into account, our results overlap with his. We also provide a fit of the Trojan Horse data that properly takes into account finite residual energy resolution of the data.

  3. Quasielastic knockout of light fragments from {sup 12}C and {sup 16}O nuclei by intermediate-energy pions

    SciTech Connect

    Abramov, B. M.; Borodin, Yu. A.; Bulychjov, S. A.; Dukhovskoy, I. A.; Krutenkova, A. P.; Kulikov, V. V. Martemianov, M. A.; Matsuk, M. A.; Tarasov, V. E.; Turdakina, E. N.; Khanov, A. I.

    2007-07-15

    Quasielastic deuteron and triton knockout from {sup 12}C and {sup 16}O nuclei has been studied infull kinematics using a 0.72-GeV/c pion beam. The momentum distributions of the intranuclear quasideuteron motion, excitation-energy spectra of the residual nuclei, and the effective numbers N{sub d}{sup eff} of quasideuterons are determined. The parameters of the quasideuteron intranuclear motion are in reasonable agreement with the results obtained in other beams. The N{sub d}{sup eff} in the nuclei from {sup 6}Li to {sup 16}O measured in full kinematics are virtually independent of the atomic number in contrast to the analogous values in the inclusive deuteron-knockout reaction induced by protons. The phenomenon of triton knockout from these nuclei is observed, which makes possible estimation of the cross section of backward pion-triton elastic scattering in yet unexplored regions of energy and momentum transfer.

  4. Experimental controls on D/H and 13C/12C ratios of kerogen, bitumen and oil during hydrous pyrolysis

    USGS Publications Warehouse

    Schimmelmann, A.; Boudou, J.-P.; Lewan, M.D.; Wintsch, R.P.

    2001-01-01

    Large isotopic transfers between water-derived hydrogen and organic hydrogen occurred during hydrous pyrolysis experiments of immature source rocks, in spite of only small changes in organic 13C/12C. Experiments at 330 ??C over 72 h using chips or powder containing kerogen types I and III identify the rock/water ratio as a main factor affecting ????D for water and organic hydrogen. Our data suggest that larger rock permeability and smaller rock grain size increase the H-isotopic transfer between water-derived hydrogen and thermally maturing organic matter. Increasing hydrostatic pressure may have a similar effect, but the evidence remains inconclusive. ?? 2001 Elsevier Science Ltd. All rights reserved.

  5. Elastic scattering and total reaction cross sections for the B8, Be7, and Li6 +12C systems

    NASA Astrophysics Data System (ADS)

    Barioni, A.; Zamora, J. C.; Guimarães, V.; Paes, B.; Lubian, J.; Aguilera, E. F.; Kolata, J. J.; Roberts, A. L.; Becchetti, F. D.; Villano, A.; Ojaruega, M.; Jiang, H.

    2011-07-01

    Angular distributions for the elastic scattering of B8, Be7, and Li6 on a C12 target have been measured at Elab=25.8, 18.8, and 12.3 MeV, respectively. The analyses of these angular distributions have been performed in terms of the optical model using Woods-Saxon and double-folding type potentials. The effect of breakup in the elastic scattering of 8B+12C is investigated by performing coupled-channels calculations with the continuum discretized coupled-channel method and cluster-model folding potentials. Total reaction cross sections were deduced from the elastic-scattering analysis and compared with published data on elastic scattering of other weakly and tightly bound projectiles on C12, as a function of energy. With the exception of He4 and O16, the data can be described using a universal function for the reduced cross sections.

  6. Vibration-rotation spectroscopic database on acetylene, X ˜ 1 Σg + (12C2H2)

    NASA Astrophysics Data System (ADS)

    Amyay, B.; Fayt, A.; Herman, M.; Vander Auwera, J.

    2016-06-01

    A complete set of calculated vibration-rotation energies of 12C2H2 ( X ˜ 1 Σg + ) is provided for all vibrational states up to 13 000 cm-1 and some at higher energies, with rotational (J) and vibrational angular momentum (l) quantum numbers such that 0 ≤ J ≤ 100 and 0 ≤ |l| ≤ 20, respectively. The calculation is performed using a global effective Hamiltonian and related spectroscopic constants from the literature [B. Amyay et al., J. Mol. Spectrosc. 267, 80 (2011)], based on the polyad model. The numerical values of all related polyad matrix elements are also provided. The model and equations for the Hamiltonian matrix elements are gathered. The experimental acetylene database used for determining the parameters is listed.

  7. Direct measurement of {sup 4}He({sup 12}C, {sup 16}O){gamma} reaction near stellar energy

    SciTech Connect

    Fujita, K.; Sagara, K.; Teranishi, T.; Goto, T.; Iwabuchi, R.; Matsuda, S.; Oba, N.; Taniguchi, M.; Yamaguchi, H.

    2010-08-12

    A cross section measurement with a direct {sup 16}O detection method for the reaction energy from E{sub cm} = 2.4 down to 0.7 MeV is planned at Kyushu University Tandem Laboratory (KUTL). To perform the experiment successfully and to get the quantitative information of the cross section within the 10% error, we have newly developed several instruments in 2009, such as a blow-in type windowless gas target and movable slit system placed in the recoil mass separator. By using the windowless blow-in gas target, a pressure of 24 Torr was achieved. The effective thickness along the beam axis was measured by p+{sup 4}He scattering. Thanks to the movable slits installed in a recoil mass separator and the trajectory analysis, we found effective reduction of background conditions from the {sup 12}C beam.

  8. The Rovibrational Intensities of Five Absorption Bands of (12)C(16)O2 Between 5218 and 5349/cm

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Brown, Linda R.; Chackerian, Charles, Jr.; Freedman, Richard S.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Absolute line intensities, band intensities, and Herman-Wallis parameters were measured for the (01(sup 1)2)(sub I) from (00(sup 0)0)(sub I) perpendicular band of (12)C(16)O2 centered at 5315/cm, along with the three nearby associated hot bands: (10(sup 0)2)(sub II) from (01(sup 1)0)(sub I) at 5248/cm, (02(sup 2))(sub I) from (01(sup 1)0)(sub I) at 5291/cm, and (10(sup 0)2)(sub I) from (01(sup 1)0)(sub I) at 5349/cm. The nearby parallel hot band (30(sup 0))(sub I) from (10(sup 0)0)(sub II) at 5218/cm was also included in this study.

  9. Precise Branching Ratios to Unbound 12C States from 12N and 12B (beta)-Decays

    SciTech Connect

    Hyldegaard, S; Forssen, C; Alcorta, M; Barker, F C; Bastin, B; Borge, M G; Boutami, R; Brandenburg, S; Buscher, J; Dendooven, P; Diget, C A; Van Duppen, P; Eronen, T; Fox, S; Fulton, B R; Fynbo, H U; Huikari, J; Huyse, M; Jeppesen, H B; Jokinen, A; Jonson, B; Jungmann, K; Kankainen, A; Kirsebom, O; Madurga, M; Moore, I; Navratil, P; Nilsson, T; Nyman, G; Onderwater, G G; Penttila, H; Perajarvi, K; Raabe, R; Riisager, K; Rinta-Antila, S; Rogachevskiy, A; Saastamoinen, A; Sohani, M; Tengblad, O; Traykov, E; Vary, J P; Wang, Y; Wilhelmsen, K; Wilschut, H W; Aysto, J

    2008-08-20

    Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in {sup 12}C from {sup 12}N and {sup 12}B {beta}-decays. In the first the three {alpha}-particles emitted after {beta}-decay are measured in coincidence in separate detectors, while in the second method {sup 12}N and {sup 12}B are implanted in a detector and the summed energy of the three {alpha}-particles is measured directly. For the narrow states at 7.654 MeV (0{sup +}) and 12.71 MeV (1{sup +}) the resulting branching ratios are both smaller than previous measurements by a factor of {approx_equal} 2. The experimental results are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.

  10. Study of 12C excited states decaying into three α particles using the thick target inverse kinematic technique

    NASA Astrophysics Data System (ADS)

    Barbui, M.; Hagel, K.; Gauthier, J.; Wuenschel, S.; de Souza, R. T.; Hudan, S.; Fang, D.; Goldberg, V. Z.; Zheng, H.; Giuliani, G.; Rapisarda, G.; Kim, E.-J.; Liu, X.; Natowitz, J. B.

    2016-05-01

    We will show that the Thick Target Inverse Kinematics (TTIK) technique can be used to investigate the breakup of excited selfconjugate nuclei into many alpha particles. Two test runs were performed at Cyclotron Institute of Texas A&M University to study the reaction 20Ne+α at maximum beam energies of 10 and 12 AMeV. Due to the limited statistics, only events with alpha multiplicity up to three were analyzed. The analysis of the three α-particle emission data allowed the identification of the Hoyle state and other 12C excited states decaying into three alpha particles. The results will be shown and compared with other data available in the literature.

  11. A Survey of Beam Asymmetries in Semi-exclusive Electron Scattering on {sup 4}He and {sup 12}C

    SciTech Connect

    Dan Protopopescu

    2002-12-01

    A study of the polarized electron beam asymmetry in semi-exclusive (e,e{prime}p) reactions on {sup 4}He and {sup 12}C over a large kinematic range has been performed. The beam asymmetry A{prime}{sub LT} is related to the imaginary part of the longitudinal-transverse interference and therefore it vanishes in reactions proceeding through a channel with a single dominant mechanism. In quasifree nucleon knockout, the helicity asymmetry provides an unambiguous signature for the interference between direct knockout and rescattering amplitudes. The data were taken in April-May 1999 using polarized beams of energies between 2.2 and 4.4 GeV, with the CEBAF Large Acceptance Spectrometer (CLAS) detector located in Hall B at the Jefferson Laboratory, VA. The measured asymmetries compare well with the theoretical predictions.

  12. Interaction of 1p nuclei: Case of 14N+12C Elastic Scattering at 21.0 MeV

    NASA Astrophysics Data System (ADS)

    Burtebayev, N.; Alimov, D.; Boztosun, I.; Burtebayeva, J.; Kerimkulov, Zh K.; Nassurlla, M.; Amangeldy, N.; Morzabayev, A. K.; Sakhiev, S. K.; Hamada, Sh

    2015-04-01

    Optical model analysis has been conducted for the elastic scattering of 1p-shell nuclei around the Coulomb barrier energies. We have used both microscopic double-folding and phenomenological potentials for the real part of the complex nuclear potential. The imaginary potential has the shape of phenomenological Wood-Saxon volume. The case 14N+12C for 1p-shell nuclei has been studied in detail and it is noticed that a large normalization of the strength of the double-folding real potential is needed to explain the structure observed in the experimental data. A good agreement between experimental data and theoretical results is obtained for the phenomenological potential case.

  13. LASER BIOLOGY AND MEDICINE: Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air

    NASA Astrophysics Data System (ADS)

    Stepanov, E. V.

    2002-11-01

    Tunable diode lasers (TDLs) are applied to the diagnostics of gastroenterological diseases using respiratory tests and preparations enriched with the stable 13C isotope. This method of the analysis of the 13C/12C isotope ratio in CO2 in exhaled air is based on the selective measurement of the resonance absorption at the vibrational — rotational structure of 12CO2 and 13CO2. The CO2 transmission spectra in the region of 4.35 μm were measured with a PbEuSe double-heterostructure TDL. The accuracy of carbon isotope ratio measurements in CO2 of exhaled air performed with the TDL was ~0.5%. The data of clinical tests of the developed laser-based analyser are presented.

  14. Low-energy cross sections in the {sup 12}C({alpha},{gamma}){sup 16}O reaction

    SciTech Connect

    Katsuma, M.

    2008-09-15

    The low-energy {sup 12}C({alpha},{gamma}){sup 16}O reaction is analyzed with the potential model. The potentials are chosen from the deep potential describing the {alpha}-particle nuclear rainbow phenomena at high energies. Below E{sub c.m.}=1 MeV, the cross section is found to be dominated by the E2 transition to the ground state of {sup 16}O. No enhancement of the E1 component at low energies is predicted. The extrapolated astrophysical S-factors at E{sub c.m.}=0.3 MeV are S{sub E2}=150 keV b and S{sub E1}=3 keV b.

  15. A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples

    SciTech Connect

    Kelly, James F.; Sams, Robert L.; Blake, Thomas A.; Newburn, Matthew K.; Moran, James J.; Alexander, M. L.; Kreuzer, Helen W.

    2012-02-06

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO{sub 2} samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO{sub 2} near 2307 cm{sup -1} (4.34 {mu}m). This initial CAS system can achieve relative isotopic precision of about 10 ppm {sup 13}C, or {approx}1{per_thousand} (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO{sub 2} concentrations {approx}400 to 750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to {approx}2 Torr. Overall {sup 13}C/{sup 12}C ratios can be calibrated to {approx}2{per_thousand} accuracy with diluted CO{sub 2} standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1,000 scans are co-added in {approx}10 sec. The CAS is meant to work directly with converted CO{sub 2} samples from a Laser Ablation-Catalytic-Combustion (LA CC) micro-sampler to provide {sup 13}C/{sup 12}C ratios of small biological isolates with spatial resolutions {approx}50 {mu}m.

  16. Measurement of fragmentation cross sections of 12C ions on a thin gold target with the FIRST apparatus

    NASA Astrophysics Data System (ADS)

    Toppi, M.; Abou-Haidar, Z.; Agodi, C.; Alvarez, M. A. G.; Aumann, T.; Balestra, F.; Battistoni, G.; Bocci, A.; Böhlen, T. T.; Boudard, A.; Brunetti, A.; Carpinelli, M.; Cirio, R.; Cirrone, G. A. P.; Cortes-Giraldo, M. A.; Cuttone, G.; de Napoli, M.; Durante, M.; Fernández-García, J. P.; Finck, Ch.; Golosio, B.; Iarocci, E.; Iazzi, F.; Ickert, G.; Introzzi, R.; Juliani, D.; Krimmer, J.; Kummali, A. H.; Kurz, N.; Labalme, M.; Leifels, Y.; Le Fèvre, A.; Leray, S.; Marchetto, F.; Monaco, V.; Morone, M. C.; Nicolosi, D.; Oliva, P.; Paoloni, A.; Piersanti, L.; Pleskac, R.; Randazzo, N.; Rescigno, R.; Romano, F.; Rossi, D.; Rosso, V.; Rousseau, M.; Sacchi, R.; Sala, P.; Salvador, S.; Sarti, A.; Scheidenberger, C.; Schuy, C.; Sciubba, A.; Sfienti, C.; Simon, H.; Sipala, V.; Spiriti, E.; Tropea, S.; Vanstalle, M.; Younis, H.; Patera, V.; FIRST Collaboration

    2016-06-01

    A detailed knowledge of the light ions interaction processes with matter is of great interest in basic and applied physics. As an example, particle therapy and space radioprotection require highly accurate fragmentation cross-section measurements to develop shielding materials and estimate acute and late health risks for manned missions in space and for treatment planning in particle therapy. The Fragmentation of Ions Relevant for Space and Therapy experiment at the Helmholtz Center for Heavy Ion research (GSI) was designed and built by an international collaboration from France, Germany, Italy, and Spain for studying the collisions of a 12C ion beam with thin targets. The collaboration's main purpose is to provide the double-differential cross-section measurement of carbon-ion fragmentation at energies that are relevant for both tumor therapy and space radiation protection applications. Fragmentation cross sections of light ions impinging on a wide range of thin targets are also essential to validate the nuclear models implemented in MC simulations that, in such an energy range, fail to reproduce the data with the required accuracy. This paper presents the single differential carbon-ion fragmentation cross sections on a thin gold target, measured as a function of the fragment angle and kinetic energy in the forward angular region (θ ≲6° ), aiming to provide useful data for the benchmarking of the simulation softwares used in light ions fragmentation applications. The 12C ions used in the measurement were accelerated at the energy of 400 MeV/nucleon by the SIS (heavy ion synchrotron) GSI facility.

  17. Theoretical Investigation Optical Properties of Si12C12 Clusters and Oligomers having Potential as Excitonic Materials

    NASA Astrophysics Data System (ADS)

    Duan, Xiaofeng; Burggraf, Larry

    2015-03-01

    SiC clusters may have potential in 2-D exciton circuits. We determined the most stable SinCn isomer structures (n <=12) out of hundreds to thousands isomers using a method combining Stochastic Potential Surface Search and Pseududopotential Plane-Wave Density Functional Theory Car-Parinello Molecular Dynamics simulated annealing (PSPW-CPMD-SA). Four low-energy Si12C12 isomer structures are discussed to illustrate the varying optical properties of clusters with structures: i) cage type with C- and Si- segregations, ii) symmetric type formed having π-stacked C aromatic rings and exterior Si regions, iii) nearly planar bowl with C fullerene fragment surrounded by Si atoms, and iv) symmetrical SiC cluster having alternate SiC bonding in the structure. We employed B3LYP and PBE0 functionals and both cc-pVTZ and aug-cc-pVTZ basis sets to perform TDDFT calculations of excitation energies and photo-absorption spectra to show how structure and bonding patterns affect photo excitations in different types of SiC clusters. The electron and the hole charge distribution patterns in excitation were calculated for major photoabsorption transitions, reported for the most stable isomer, closo Si12C12. To understand electric field effects we also calculated dynamical polarizabilities for all the four structures using Coupled Perturbed Hartree-Fock (CPHF) at B3LYP/aug-cc-pVTZ and PBE0/aug-cc-pVTZ level of theory. We gratefully acknowledge support from the Air Force Office of Scientific Research in a program managed by Dr Michael Berman.

  18. A concise and efficient synthesis of benzimidazo[1,2-c]quinazolines through CuI-catalyzed intramolecular N-arylations

    PubMed Central

    Pang, Xinlong; Li, Ming

    2015-01-01

    Summary A series of functionalized benzimidazo[1,2-c]quinazoline derivatives was obtained in excellent yields under mild conditions through a CuI-catalyzed Ullmann N-arylation starting from easily available starting materials. PMID:26734086

  19. A concise and efficient synthesis of benzimidazo[1,2-c]quinazolines through CuI-catalyzed intramolecular N-arylations.

    PubMed

    Pang, Xinlong; Chen, Chao; Li, Ming; Xi, Chanjuan

    2015-01-01

    A series of functionalized benzimidazo[1,2-c]quinazoline derivatives was obtained in excellent yields under mild conditions through a CuI-catalyzed Ullmann N-arylation starting from easily available starting materials. PMID:26734086

  20. Definite evidence of the Landau-Zener transition in nucleus-nucleus collisions

    SciTech Connect

    Imanishi, B.; von Oertzen, W.; Voit, H.

    1987-01-01

    It is shown that the Landau-Zener transition mechanism due to the formation of molecular orbitals of the active neutron exists in the inelastic scattering /sup 13/C(/sup 12/C, /sup 12/C)/sup 13/C/sup */ (3.086 MeV, (1/2)/sup +/). The evidence stems from characteristic changes of the angular distributions observed as a function of the incident energy.

  1. Dynamic risk control by human nucleus accumbens.

    PubMed

    Nachev, Parashkev; Lopez-Sosa, Fernando; Gonzalez-Rosa, Javier Jesus; Galarza, Ana; Avecillas, Josue; Pineda-Pardo, Jose Angel; Lopez-Ibor, Juan José; Reneses, Blanca; Barcia, Juan Antonio; Strange, Bryan

    2015-12-01

    Real-world decisions about reward often involve a complex counterbalance of risk and value. Although the nucleus accumbens has been implicated in the underlying neural substrate, its criticality to human behaviour remains an open question, best addressed with interventional methodology that probes the behavioural consequences of focal neural modulation. Combining a psychometric index of risky decision-making with transient electrical modulation of the nucleus accumbens, here we reveal profound, highly dynamic alteration of the relation between probability of reward and choice during therapeutic deep brain stimulation in four patients with treatment-resistant psychiatric disease. Short-lived phasic electrical stimulation of the region of the nucleus accumbens dynamically altered risk behaviour, transiently shifting the psychometric function towards more risky decisions only for the duration of stimulation. A critical, on-line role of human nucleus accumbens in dynamic risk control is thereby established. PMID:26428667

  2. The Impact of the Uncertainties in the 12C(α,γ)16O Reaction Rate on the Asteroseismology of ZZ Ceti Stars: First Results

    NASA Astrophysics Data System (ADS)

    De Gerónimo, Francisco C.; Córsico, Alejandro H.; Althaus, Leandro G.; Romero, Alejandra D.

    2015-06-01

    We assess for the first time the impact that the uncertainties affecting the 12C(α,γ)16O reaction rate have on the asteroseismological inferences of ZZ Ceti stars. For our adopted test-case, the well studied DAV star G117-B15A, we found that the incomplete knowledge of the 12C(α,γ)16O nuclear reaction rate results in a moderate dispersion of the structural parameters of the asteroseismological model.

  3. Conformational restriction through C alpha i <--> C alpha i cyclization: Ac12c, the largest cycloaliphatic C alpha,alpha- disubstituted glycine known.

    PubMed

    Saviano, M; Iacovino, R; Menchise, V; Benedetti, E; Bonora, G M; Gatos, M; Graci, L; Formaggio, F; Crisma, M; Toniolo, C

    2000-02-01

    Two complete series of N-protected, monodispersed oligopeptide esters to the pentamer level from 1-aminocyclododecane-1-carboxylic acid (Ac(12)c), an alpha-amino acid conformationally constrained through C(alpha)(i) <--> C(alpha)(i) cyclization, and either L-Ala or Aib residues, along with the N-protected Ac(12)c homopeptide alkylamide series from monomer to trimer, have been synthesized by solution methods and fully characterized. The solution-preferred conformations of these peptides have been assessed by Fourier transform ir absorption and (1)H-nmr techniques. Moreover, the molecular structures of one derivative (Z-Ac(12)c-OH) and three peptides [the tripeptide ester Z-L-Ala-Ac(12)c-L-Ala-OMe, the tripeptide alkylamide Z-(Ac(12)c)(3)-NHiPr, and the tetrapeptide ester Z-(Aib)(2)-Ac(12)c-Aib-OtBu (Aib, alpha-aminoisobutyric acid)] have been determined in the crystal state by x-ray diffraction. The results obtained point to the conclusion that beta-bends and 3(10)-helices are preferentially adopted by peptides based on Ac(12)c, the largest cycloaliphatic C-disubstituted glycine known. A comparison with the structural tendencies extracted from published works on peptides from Aib, the prototype of C-disubstituted glycines, and the other extensively studied members of the class of 1-aminocycloalkane-1-carboxylic acids (Ac(n) c, with n = 3-9), is made and the implications for the use of the Ac(12)c residue in the Ac(n) c scan approach of conformationally restricted analogues of bioactive peptides are briefly discussed. PMID:10679624

  4. Testing string dynamics in lepton nucleus reactions

    SciTech Connect

    Gyulassy, M.; Pluemer, M.

    1989-10-01

    The sensitivity of nuclear attenuation of 10-100 GeV lepton nucleus ({ell}A) reactions to space-time aspects of hadronization is investigated within the context of the Lund string model. We consider two mechanisms for attenuation in a nucleus: final state cascading and string flip excitations. Implications for the evolution of the energy density in nuclear collisions are discussed. 16 refs., 10 figs.

  5. Volumes of cochlear nucleus regions in rodents.

    PubMed

    Godfrey, Donald A; Lee, Augustine C; Hamilton, Walter D; Benjamin, Louis C; Vishwanath, Shilpa; Simo, Hermann; Godfrey, Lynn M; Mustapha, Abdurrahman I A A; Heffner, Rickye S

    2016-09-01

    The cochlear nucleus receives all the coded information about sound from the cochlea and is the source of auditory information for the rest of the central auditory system. As such, it is a critical auditory nucleus. The sizes of the cochlear nucleus as a whole and its three major subdivisions - anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), and dorsal cochlear nucleus (DCN) - have been measured in a large number of mammals, but measurements of its subregions at a more detailed level for a variety of species have not previously been made. Size measurements are reported here for the summed granular regions, DCN layers, AVCN, PVCN, and interstitial nucleus in 15 different rodent species, as well as a lagomorph, carnivore, and small primate. This further refinement of measurements is important because the granular regions and superficial layers of the DCN appear to have some different functions than the other cochlear nucleus regions. Except for DCN layers in the mountain beaver, all regions were clearly identifiable in all the animals studied. Relative regional size differences among most of the rodents, and even the 3 non-rodents, were not large and did not show a consistent relation to their wide range of lifestyles and hearing parameters. However, the mountain beaver, and to a lesser extent the pocket gopher, two rodents that live in tunnel systems, had relative sizes of summed granular regions and DCN molecular layer distinctly larger than those of the other mammals. Among all the mammals studied, there was a high correlation between the size per body weight of summed granular regions and that of the DCN molecular layer, consistent with other evidence for a close relationship between granule cells and superficial DCN neurons. PMID:27435005

  6. Commissural axons of the mouse cochlear nucleus.

    PubMed

    Brown, M Christian; Drottar, Marie; Benson, Thane E; Darrow, Keith

    2013-05-01

    The axons of commissural neurons that project from one cochlear nucleus to the other were studied after labeling with anterograde tracer. Injections were made into the dorsal subdivision of the cochlear nucleus in order to restrict labeling only to the group of commissural neurons that gave off collaterals to, or were located in, this subdivision. The number of labeled commissural axons in each injection was correlated with the number of labeled radiate multipolar neurons, suggesting radiate neurons as the predominant origin of the axons. The radiate commissural axons are thick and myelinated, and they exit the dorsal acoustic stria of the injected cochlear nucleus to cross the brainstem in the dorsal half, near the crossing position of the olivocochlear bundle. They enter the opposite cochlear nucleus via the dorsal and ventral acoustic stria and at its medial border. Reconstructions of single axons demonstrate that terminations are mostly in the core and typically within a single subdivision of the cochlear nucleus. Extents of termination range from narrow to broad along both the dorsoventral (i.e., tonotopic) and the rostrocaudal dimensions. In the electron microscope, labeled swellings form synapses that are symmetric (in that there is little postsynaptic density), a characteristic of inhibitory synapses. Our labeled axons do not appear to include excitatory commissural axons that end in edge regions of the nucleus. Radiate commissural axons could mediate the broadband inhibition observed in responses to contralateral sound, and they may balance input from the two ears with a quick time course. PMID:23124982

  7. Improved Cloud Condensation Nucleus Spectrometer

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2010-01-01

    An improved thermal-gradient cloud condensation nucleus spectrometer (CCNS) has been designed to provide several enhancements over prior thermal- gradient counters, including fast response and high-sensitivity detection covering a wide range of supersaturations. CCNSs are used in laboratory research on the relationships among aerosols, supersaturation of air, and the formation of clouds. The operational characteristics of prior counters are such that it takes long times to determine aerosol critical supersaturations. Hence, there is a need for a CCNS capable of rapid scanning through a wide range of supersaturations. The present improved CCNS satisfies this need. The improved thermal-gradient CCNS (see Figure 1) incorporates the following notable features: a) The main chamber is bounded on the top and bottom by parallel thick copper plates, which are joined by a thermally conductive vertical wall on one side and a thermally nonconductive wall on the opposite side. b) To establish a temperature gradient needed to establish a supersaturation gradient, water at two different regulated temperatures is pumped through tubes along the edges of the copper plates at the thermally-nonconductive-wall side. Figure 2 presents an example of temperature and supersaturation gradients for one combination of regulated temperatures at the thermally-nonconductive-wall edges of the copper plates. c) To enable measurement of the temperature gradient, ten thermocouples are cemented to the external surfaces of the copper plates (five on the top plate and five on the bottom plate), spaced at equal intervals along the width axis of the main chamber near the outlet end. d) Pieces of filter paper or cotton felt are cemented onto the interior surfaces of the copper plates and, prior to each experimental run, are saturated with water to establish a supersaturation field inside the main chamber. e) A flow of monodisperse aerosol and a dilution flow of humid air are introduced into the main

  8. The extended chain compounds Ln {sub 12}(C{sub 2}){sub 3}I{sub 17} (Ln=Pr, Nd, Gd, Dy): Synthesis, structure and physical properties

    SciTech Connect

    Ryazanov, Mikhail; Mattausch, Hansjuergen; Simon, Arndt

    2007-04-15

    The title compounds are obtained in high yield from stoichiometric mixtures of Ln, LnI{sub 3} and graphite, heated at 900-950 deg. C in welded Ta containers. The crystal structures of new Pr and Nd phases determined by single-crystal X-ray diffraction are related to those of other Ln {sub 12}(C{sub 2}){sub 3}I{sub 17}-type compounds (C 2/c, a=19.610(1) and 19.574(4) A, b=12.406(2) and 12.393(3) A, c=19.062(5) and 19.003(5) A, {beta}=90.45(3){sup o} and 90.41(3){sup o}, for Pr{sub 12}(C{sub 2}){sub 3}I{sub 17} and Nd{sub 12}(C{sub 2}){sub 3}I{sub 17}, respectively). All compounds contain infinite zigzag chains of C{sub 2}-centered metal atom octahedra condensed by edge-sharing into the [tcc] {sub {infinity}} sequence (c=cis, t=trans) and surrounded by edge-bridging iodine atoms as well as by apical iodine atoms that bridge between chains. The polycrystalline Gd{sub 12}(C{sub 2}){sub 3}I{sub 17} sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation (Ln {sup 3+}){sub 12}(C{sub 2} {sup 6-}){sub 3}(I{sup -}){sub 17}(e{sup -}) under the assumption that one extra electron is localized in metal-metal bonding. The magnetization measurements on Nd{sub 12}(C{sub 2}){sub 3}I{sub 17}, Gd{sub 12}(C{sub 2}){sub 3}I{sub 17} and Dy{sub 12}(C{sub 2}){sub 3}I{sub 17} indicate the coexistence of competing magnetic interactions leading to spin freezing at T {sub f}=5 K for the Gd phase. The Nd and Dy compounds order antiferromagnetically at T {sub N}=25 and 29 K, respectively. For Dy{sub 12}(C{sub 2}){sub 3}I{sub 17}, a metamagnetic transition is observed at a critical magnetic field H{approx}25 kOe. - Graphical abstract: Zigzag chains of edge-sharing metal atom octahedra in Ln {sub 12}(C{sub 2}){sub 3}I{sub 17}.

  9. Investigation of carbon-coated lithiated Li{sub 4+x}Ti{sub 5}O{sub 12}/C for lithium-ion batteries

    SciTech Connect

    Pan, Mengjie; Zhang, Lin; Gong, Lijun; Liu, Hongbo; Chen, Yuxi

    2015-11-15

    Highlights: • Lithiated Li{sub 4+x}Ti{sub 5}O{sub 12}/C with pre-stored active Li ions has been synthesized. • The first-cycle coulombic efficiency of Li{sub 4+x}Ti{sub 5}O{sub 12}/C is over 100%. • Li{sub 4+x}Ti{sub 5}O{sub 12}/C displays excellent cyclic stability and capacity retention. • TiO{sub 2} nanoparticles and carbon coating are necessary for formation of Li{sub 4+x}Ti{sub 5}O{sub 12}/C. - Abstract: Carbon-coated Li{sub 4}Ti{sub 5}O{sub 12} and lithiated Li{sub 4+x}Ti{sub 5}O{sub 12} anode materials have been synthesized using nanosized anatase TiO{sub 2} and commercial TiO{sub 2} with mixed structure as Ti sources, respectively. Microstructural investigation indicates that Li{sub 4}Ti{sub 5}O{sub 12} and Li{sub 4+x}Ti{sub 5}O{sub 12} are covered by amorphous carbon layers with thickness of 2–3 nm. Their electrochemical performance has been evaluated, which indicates that an amount of active Li ions have been pre-stored in the Li{sub 4+x}Ti{sub 5}O{sub 12} lattice during solid-state synthesis, resulting in its first-cycle coulombic efficiency over 100%. Further, Li{sub 4+x}Ti{sub 5}O{sub 12}/C exhibits higher cyclic capacities than Li{sub 4}Ti{sub 5}O{sub 12}/C at different current density. The reversible charge capacity retention of Li{sub 4+x}Ti{sub 5}O{sub 12}/C reaches 98.5% after 100 cycles, which indicates that Li{sub 4+x}Ti{sub 5}O{sub 12}/C is promising candidate anode material for long lifetime lithium-ion batteries. The formation mechanism of Li{sub 4+x}Ti{sub 5}O{sub 12}/C has been discussed, in which the nanosized anatase TiO{sub 2} with high chemical activity and the carbon coating play key roles for the formation of Li{sub 4+x}Ti{sub 5}O{sub 12}/C.

  10. PET monitoring of cancer therapy with 3He and 12C beams: a study with the GEANT4 toolkit.

    PubMed

    Pshenichnov, Igor; Larionov, Alexei; Mishustin, Igor; Greiner, Walter

    2007-12-21

    We study the spatial distributions of beta(+)-activity produced by therapeutic beams of (3)He and (12)C ions in various tissue-like materials. The calculations were performed within a Monte Carlo model for heavy-ion therapy (MCHIT) based on the GEANT4 toolkit. The contributions from positron-emitting nuclei with T(1/2) > 10 s, namely (10,11)C, (13)N, (14,15)O, (17,18)F and (30)P, were calculated and compared with experimental data obtained during and after irradiation, where available. Positron-emitting nuclei are created by a (12)C beam in fragmentation reactions of projectile and target nuclei. This leads to a beta(+)-activity profile characterized by a noticeable peak located close to the Bragg peak in the corresponding depth-dose distribution. This can be used for dose monitoring in carbon-ion therapy of cancer. In contrast, as most of the positron-emitting nuclei are produced by a (3)He beam in target fragmentation reactions, the calculated total beta(+)-activity during or soon after the irradiation period is evenly distributed within the projectile range. However, we predict also the presence of (13)N, (14)O, (17,18)F created in charge-transfer reactions by low-energy (3)He ions close to the end of their range in several tissue-like media. The time evolution of beta(+)-activity profiles was investigated for both kinds of beams. We found that due to the production of (18)F nuclides the beta(+)-activity profile measured 2 or 3 h after irradiation with (3)He ions will have a distinct peak correlated with the maximum of depth-dose distribution. We also found certain advantages of low-energy (3)He beams over low-energy proton beams for reliable PET monitoring during particle therapy of shallow-located tumours. In this case the distal edge of beta(+)-activity distribution from (17)F nuclei clearly marks the range of (3)He in tissues. PMID:18065840

  11. 13C/12C and 15N/14N Isotope Analysis to Characterize Natural Degradation of Atrazine: Evidence from Parent and Daughter Compound Values

    NASA Astrophysics Data System (ADS)

    Elsner, Martin; Meyer, Armin

    2013-04-01

    The mobile and still herbicidal metabolites desethylatrazine (DEA) and desisopropylatrazine (DIA) are frequently detected together with its parent compound atrazine (Atz) in the aquatic environment. Interpretation of their transformation state is often difficult with current methods, which are mainly measuring concentrations. Alternatively, compound specific isotope analyses (CSIA) has become a novel tool to detect degradation processes of contaminants in groundwater. The aim of our study was to investigate on the lab scale 13C/12C and 15N/14N isotope trends in parent and daughter compounds associated with different degradation scenarios of atrazine likely to occur in the environment. Thus atrazine was dealkylated with (i) permanganate and (ii) the bacterium Rhodococcus sp. NI86/21. In both transformations, 13C/12C ratios of atrazine increased strongly (epsilon carbon/permanganate = -4.6 ± 0.6 ‰ and epsilon carbon/Rhodoccoccus = -3.8 ± 0.2 ‰) whereas nitrogen isotope fractionation was small. 13C/12C ratios of DEA showed the following trends. (i) When DEA was formed as only product (Atz + permanganate) 13C/12C remained constant, close to the initial value of Atz. (ii) When DEA was formed together with deisopropylatrazine (biodegradation of Atz) 13C/12C increased, but only within 2‰. (iii) When DEA and DIA was further biodegraded, 13C/12C increased for both metabolites up to 9‰. Thus strong enrichment of 13C/12C in the metabolites in comparison to Atz can give strong testimony for further breakdown of the metabolite.

  12. Computer program for parameterization of nucleus-nucleus electromagnetic dissociation cross sections

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Townsend, Lawrence W.; Badavi, Forooz F.

    1988-01-01

    A computer subroutine parameterization of electromagnetic dissociation cross sections for nucleus-nucleus collisions is presented that is suitable for implementation in a heavy ion transport code. The only inputs required are the projectile kinetic energy and the projectile and target charge and mass numbers.

  13. K--Nucleus Elastic Scattering at IntermediateEnergies in the Isobar-Doorway Model

    NASA Astrophysics Data System (ADS)

    Toyama, F. M.

    1983-11-01

    The differential cross sections for the K--nucleus elastic scattering at about PK = 800 MeV/c are calculated in the phenomenological isobar-doorway model. The many-body corrections on Y* resonances in nuclei are represented by the resonance energy shift Δ E and width-modification factor β. The parametrizations given by Gopal et al. are used for the resonance amplitudes. The effects of Δ E and β on the cross sections are investigated in detail. The results are compared with the available experimental data for the K- elastic scattering on 12C and 40Ca at PK = 800 MeV/c. The calculated cross sections are in good agreement with the data. However, the cross sections are not very sensitive to Δ E and β.

  14. Measurements of parity violation in neutron-nucleus reactions

    SciTech Connect

    Seestrom, S.J.; Bowman, C.D.; Bowman, J.D.; Knudson, J.; Mortensen, R.; Penttila, S.; Szymanski, J.J.; Wender, S.A.; Yoo, S.H.; Yuan, V.W. ); Frankle, C.M.; Gould, C.R.; Haase, D.G.; Mitchell, G.E. Triangle Universities Nuclear Lab., Durham, NC ); Roberson, N.R.; Zhu, X. (Duke Univ., Durham, NC

    1991-01-01

    In this talk I describe a new generation of experiments studying the weak interaction between nucleons. Measurements of the effect of this interaction are few in number and the significance of the observed effects are generally small. It is well known that the weak interaction violates parity. This was first experimentally established by C. S. Wu through measurement of an asymmetry of electrons emitted in the beta-decay of polarized {sup 60}Co. The measured asymmetry was large because beta decay is a weak interaction process. For a process in which the strong interaction can contribute, we expect much smaller asymmetries, of order 10{sup {minus}7}. In the work I will describe here we study the effects of the weak interaction through the signal of the parity violation associated with that interaction. There are two basic classes of experiment used to detect parity violation. The first relies on the measurement of a cross section or width that would vanish if parity were conserved. One example of this type of experiment in nuclear physics is the decay of an unnatural parity state to a 0+ nucleus and an {alpha}-particle. Such measurements have been made for two nuclei: {sup 16}O(2{sup {minus}}) {implies} {sup 12} C(g.s) + {alpha} and {sup 20}N{var epsilon}(1{sup +}) {implies} {sup 16} O(g.s) + {alpha}. Parity-violating widths as small as of 10{sup {minus}10} eV have been measured in these experiments. The second class of experiments involves a measurement of pseudo-scalar observables which are odd under parity inversion. These involve correlations between spin and linear angular momenta, for example circular polarization of {gamma}-rays ({sigma}{sub {gamma}} {center dot} {kappa}{sub {gamma}}) or longitudinal analyzing power ({sigma}{sub p} {center dot} {kappa}{sub p}). 20 refs., 6 figs.

  15. Meson-exchange currents and quasielastic predictions for charged-current neutrino-12C scattering in the superscaling approach

    NASA Astrophysics Data System (ADS)

    Megias, G. D.; Donnelly, T. W.; Moreno, O.; Williamson, C. F.; Caballero, J. A.; González-Jiménez, R.; De Pace, A.; Barbaro, M. B.; Alberico, W. M.; Nardi, M.; Amaro, J. E.

    2015-04-01

    We evaluate and discuss the impact of meson-exchange currents (MECs) on charged-current quasielastic neutrino cross sections. We consider the nuclear transverse response arising from two-particle two-hole states excited by the action of electromagnetic, purely isovector meson-exchange currents in a fully relativistic framework based on the work by the Torino Collaboration [A. D. Pace, M. Nardi, W. M. Alberico, T. W. Donnelly, and A. Molinari, Nucl. Phys. A726, 303 (2003)]. An accurate parametrization of this MEC response as a function of the momentum and energy transfers involved is presented. Results of neutrino-nucleus cross sections using this MEC parametrization together with a recent scaling approach for the one-particle one-hole contributions (named SuSAv2) are compared with experimental data.

  16. High Precision Mid-Ir Spectroscopy of ^{12C^{16}O_{2}} Near 4.3 μ m

    NASA Astrophysics Data System (ADS)

    Ting, Wei-Jo; Luo, Pei-Ling; Chung, Chieh-Hsing; Chen, Hshan-Chen; Lien, Yu-Hung; Shy, Jow-Tsong

    2009-06-01

    We have observed the sub-Doppler saturation spectrum of the ^{12C^{16}O_{2}} near 4.3 μ m using a mW-level DFG (Difference Frequency Generation) source. The DFG radiation is generated by a 1-W Ti:sapphire laser and a Nd:YAG laser amplified by 10-W fiber amplifier in a 50-mm long PPLN (Periodically Poled Lithium Niobate) crystal. We are able to generate 2 mW DFG power at 4.3 μ m. The Nd:YAG laser is frequency-doubled, and frequency stabilized on one ^{127I_{2}} hyperfine transition. The Ti:sapphire laser is locked onto the center of CO_{2} transition and its frequency is measured by an OFC (Optical Frequency Comb). In this talk, we will report our recent measurements on the high J 0001 → 0000 fundamental band transitions and the hot band 0111 → 0110 transitions. To increase the signal-to-noise ratio of the observed spectra, the CO_{2} absorption cell in heated to a temperature > 500^°C.

  17. Regional localization of the gene for thyroid peroxidase to human chromosome 2p25 and mouse chromosome 12C

    SciTech Connect

    Endo, Yuichi; Onogi, Satoshi; Fujita, Teizo

    1995-02-10

    Thyroid peroxidase (TPO) plays a central role in thyroid gland function. The enzyme catalyzes two important reactions of thyroid hormone synthesis, i.e., the iodination of tyrosine residues in thyroglobulin and phenoxy-ester formation between pairs of iodinated tyrosines to generate the thyroid hormones, thyroxine and triiodothyronine. Previously, we isolated the cDNAs encoding human and mouse TPOs and assigned the human TPO gene to the short arm of chromosome 2 by somatic cell hybrid mapping. By a similar analysis of DNA from somatic cell hybrids, the human TPO gene was mapped to 2pter-p12. The mouse TPO gene was localized to chromosome 12 using a rat TPO cDNA as a probe to hybridize with mouse-hamster somatic cell hybrids. In this study, we used fluorescence in situ hybridization (FISH) to confirm the localization of human and mouse TPO genes to human chromosome 2 and mouse chromosome 12 and to assign them regionally to 2p25 and 12C, respectively. 7 refs., 1 fig.

  18. Hypernuclear production cross section in the reaction of 6Li + 12C at 2 A GeV

    NASA Astrophysics Data System (ADS)

    Rappold, C.; Saito, T. R.; Bertini, O.; Bianchin, S.; Bozkurt, V.; Kim, E.; Kavatsyuk, M.; Ma, Y.; Maas, F.; Minami, S.; Nakajima, D.; Özel-Tashenov, B.; Yoshida, K.; Achenbach, P.; Ajimura, S.; Aumann, T.; Ayerbe Gayoso, C.; Bhang, H. C.; Caesar, C.; Erturk, S.; Fukuda, T.; Göküzüm, B.; Guliev, E.; Hoffmann, J.; Ickert, G.; Ketenci, Z. S.; Khaneft, D.; Kim, M.; Kim, S.; Koch, K.; Kurz, N.; Le Fèvre, A.; Mizoi, Y.; Nungesser, L.; Ott, W.; Pochodzalla, J.; Sakaguchi, A.; Schmidt, C. J.; Sekimoto, M.; Simon, H.; Takahashi, T.; Tambave, G. J.; Tamura, H.; Trautmann, W.; Voltz, S.; Yoon, C. J.

    2015-07-01

    Hypernuclear production cross sections have been deduced for the first time with induced reaction of heavy ion beam on fixed target and by means of the invariant mass method by the HypHI Collaboration exploiting the reaction of 6Li + 12C at 2 A GeV or √{sNN} = 2.70 GeV. A production cross section of 3.9 ± 1.4 μb for 3ΛH and of 3.1 ± 1.0 μb for 4ΛH respectively in the projectile rapidity region was inferred as well as the total production cross section of the Λ hyperon was measured and found to be equal to 1.7 ± 0.8 mb. A global fit based on a Bayesian approach was performed in order to include and propagate statistical and systematic uncertainties. Production ratios of 3ΛH/4ΛH, 3ΛH/Λ and 4ΛH/Λ were included in the inference procedure. The strangeness population factors S3 and S4 of 3ΛH and 4ΛH respectively were extracted. In addition, the multiplicities of the Λ hyperon, 3ΛH, and 4ΛH together with the rapidity and transversal momentum density distributions of the observed hypernuclei were extracted and reported.

  19. In vitro degradation behavior of Fe-20Mn-1.2C alloy in three different pseudo-physiological solutions.

    PubMed

    Mouzou, Essowè; Paternoster, Carlo; Tolouei, Ranna; Purnama, Agung; Chevallier, Pascale; Dubé, Dominique; Prima, Frédéric; Mantovani, Diego

    2016-04-01

    High manganese austenitic steels such as Fe-20Mn-1.2C alloys are among the most promising candidates for biodegradable stents applications due to their high strength, high ductility and their chemical composition. In the current work, 14day static in-vitro tests were performed in controlled atmosphere to assess the degradation behavior in three common pseudo-physiological solutions, i.e. commercial Hanks' (CH), modified Hanks' (MH) and albumin-enriched Dulbecco's modified phosphate buffered saline (DPBS) solutions. The degraded samples surfaces as well as the degradation products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Degradation of material and degradation products are shown to be strongly dependent on the test medium due to the presence of different ionic species such as HCO3(-), CO3(2-), Cl(-), Ca(2+) or phosphate groups. In both MH and CH solutions, the increased content of HCO3(-) ions seems to promote MnCO3 crystal growth on sample surfaces whereas the presence of albumin and high content of phosphate ions promotes the formation of an amorphous layer rich in phosphates, iron and manganese. PMID:26838884

  20. Absolute hydrogen depth profiling using the resonant 1H(15N, αγ)12C nuclear reaction

    NASA Astrophysics Data System (ADS)

    Reinhardt, Tobias P.; Akhmadaliev, Shavkat; Bemmerer, Daniel; Stöckel, Klaus; Wagner, Louis

    2016-08-01

    Resonant nuclear reactions are a powerful tool for the determination of the amount and profile of hydrogen in thin layers of material. Usually, this tool requires the use of a standard of well-known composition. The present work, by contrast, deals with standard-less hydrogen depth profiling. This approach requires precise nuclear data, e.g. on the widely used 1 H(15 N, αγ)12 C reaction, resonant at 6.4 MeV 15 N beam energy. Here, the strongly anisotropic angular distribution of the emitted γ -rays from this resonance has been re-measured, resolving a previous discrepancy. Coefficients of (0.38 ± 0.04) and (0.80 ± 0.04) have been deduced for the second and fourth order Legendre polynomials, respectively. In addition, the resonance strength has been re-evaluated to (25.0 ± 1.5) eV, 10% higher than previously reported. A simple working formula for the hydrogen concentration is given for cases with known γ -ray detection efficiency. Finally, the absolute approach is illustrated using two examples.

  1. High-precision optical measurements of 13C/12C isotope ratios in organic compounds at natural abundance

    PubMed Central

    Zare, Richard N.; Kuramoto, Douglas S.; Haase, Christa; Tan, Sze M.; Crosson, Eric R.; Saad, Nabil M. R.

    2009-01-01

    A continuous-flow cavity ring-down spectroscopy (CRDS) system integrating a chromatographic separation technique, a catalytic combustor, and an isotopic 13C/12C optical analyzer is described for the isotopic analysis of a mixture of organic compounds. A demonstration of its potential is made for the geochemically important class of short-chain hydrocarbons. The system proved to be linear over a 3-fold injection volume dynamic range with an average precision of 0.95‰ and 0.67‰ for ethane and propane, respectively. The calibrated accuracy for methane, ethane, and propane is within 3‰ of the values determined using isotope ratio mass spectrometry (IRMS), which is the current method of choice for compound-specific isotope analysis. With anticipated improvements, the low-cost, portable, and easy-to-use CRDS-based instrumental setup is poised to evolve into a credible challenge to the high-cost and complex IRMS-based technique. PMID:19564619

  2. Rovibrational Intensities of the (00 03) ← (10 00) Dyad Absorption Bands of 12C 16O 2

    NASA Astrophysics Data System (ADS)

    Kshirsagar, Rohidas J.; Giver, Lawrence P.; Chackerian, Charles

    2000-02-01

    Absolute line intensities of 12C16O2 are experimentally measured for the first time for the (0003)I ← (1000)II band at 5687.17 cm-1 and the (0003)I ← (1000)I band at 5584.39 cm-1. The spectra were obtained using a Bomem DA8 Fourier transform spectrometer and a 25-m base-path White cell at NASA-Ames Research Center. The rotationless bandstrengths at a temperature of 296 K and the Herman-Wallis parameters are S0vib = 6.68(30) × 10-25 cm-1/(molecule/cm2); A1 = 1.4(9) × 10-4, and A2 = -1.1(5) × 10-5 for the (0003)I ← (1000)II band and S0vib = 6.07(22) × 10-25 cm-1/(molecule/cm2); A1 = 5.2(1.5) × 10-4 and A2 = -4.0(7) × 10-5 for the (0003)I ← (1000)I band.

  3. 12C/13C kinetic isotope effects in the reactions of CH4 with OH and Cl

    NASA Astrophysics Data System (ADS)

    Gupta, Mohan L.; McGrath, M. P.; Cicerone, R. J.; Rowland, F. S.; Wolfsberg, M.

    1997-11-01

    In qualitative agreement with previous MP2 level calculations of the 12C/13C kinetic isotope effects (KIEs) for H-abstraction of CH4 by OH and Cl, higher level calculations yield KIEs at 300 K that differ from the corresponding experimental values, but in different directions. At QCISD(T)/6-311+G(2df,p), the theoretical KIE for CH4+Cl is 32‰ less than the measured value, while for CH4+OH, the theoretical KIE is greater than the measured value, but only by 5‰. Noticeable differences in atmospheric model simulation studies can occur if the measured KIEs are replaced by the analogous theoretical values. For example, the effect of carbon isotopic fractionation from the CH4 + Cl reaction on stratospheric δ13CH4 will be significantly lower than that obtained by Bergamaschi et al. [1996]. It is suggested, for the CH4+OH reaction and especially for the CH4+Cl reaction, that additional KIE measurements are needed.

  4. Detection of adulteration in honey samples added various sugar syrups with 13C/12C isotope ratio analysis method.

    PubMed

    Tosun, Murat

    2013-06-01

    Honey can be adulterated in various ways. One of the adulteration methods is the addition of different sugar syrups during or after honey production. Starch-based sugar syrups, high fructose corn syrup (HFCS), glucose syrup (GS) and saccharose syrups (SS), which are produced from beet or canes, can be used for adulterating honey. In this study, adulterated honey samples were prepared with the addition of HFCS, GS and SS (beet sugar) at a ratio of 0%, 10%, 20%, 40% and 50% by weight. (13)C/(12)C analysis was conducted on these adulterated honey samples using an isotope ratio mass spectrometer in combination with an elemental analyser (EA-IRMS). As a result, adulteration using C(4) sugar syrups (HFCS and GS) could be detected to a certain extent while adulteration of honey using C(3) sugar syrups (beet sugar) could not be detected. Adulteration by using SS (beet sugar) still has a serious detection problem, especially in countries in which beet is used in manufacturing sugar. For this reason, practice and analysis methods are needed to meet this deficit and to detect the adulterations precisely in the studies that will be conducted. PMID:23411291

  5. Performances of the Front-End Electronics for the HADES RPC TOF wall on a 12C beam

    NASA Astrophysics Data System (ADS)

    Belver, D.; Cabanelas, P.; Castro, E.; Díaz, J.; Garzón, J. A.; Gil, A.; Gonzalez-Diaz, D.; Koenig, W.; Traxler, M.; Zapata, M.

    2009-05-01

    A Front-End Electronics (FEE) chain for timing accurate measurements has been developed for the RPC wall upgrade of the High-Acceptance DiElectron Spectrometer (HADES). The wall will cover an area of around 8 m with 1122 RPC cells (2244 electronic channels). The FEE chain consists of two boards: a four-channel DaughterBOard (DBO) and a 32-channel MotherBOard (MBO). The DBO uses a fast 2 GHz amplifier feeding a discriminator. The time and the charge information are encoded in the leading and the trailing edge (by a charge to width method) of an LVDS signal. Each MBO houses up to eight DBOs providing them regulated voltage supply, threshold values via DACs, test signals and collection of their trigger outputs. The MBO delivers LVDS signals to a time-to-digital converter readout board (TRB) based on HPTDC for data acquisition. In this work, we present the performance of the FEE measured using: (a) narrow electronic test pulses and (b) real signals read out in a fully instrumented RPC sextant installed in its final position at the HADES. The detector was exposed to particles coming from reactions of a 12C beam on Be and Nb targets at 2 GeV/A kinetic energy. Results for the whole electronic chain (DBO+MBO+TRB) show a timing jitter of around 40 ps/channel for pulses above 100 fC and 80 ps/channel for beam data taken with the RPC.

  6. Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

    PubMed

    Sun, Feng M; Shi, Guang Y; Wang, Hui W

    2016-07-01

    Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs. PMID:27302905

  7. Measurement of the 12C(e,e‧p)11B two-body breakup reaction at high missing momentum

    NASA Astrophysics Data System (ADS)

    Monaghan, P.; Shneor, R.; Subedi, R.; Anderson, B. D.; Aniol, K.; Annand, J.; Arrington, J.; Benaoum, H. B.; Benmokhtar, F.; Bertin, P.; Bertozzi, W.; Boeglin, W.; Chen, J. P.; Choi, Seonho; Chudakov, E.; Ciofi degli Atti, C.; Cisbani, E.; Cosyn, W.; Craver, B.; de Jager, C. W.; Feuerbach, R. J.; Folts, E.; Frullani, S.; Garibaldi, F.; Gayou, O.; Gilad, S.; Gilman, R.; Glamazdin, O.; Gomez, J.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Ibrahim, H.; Igarashi, R.; Jans, E.; Jiang, X.; Kaufman, L.; Kelleher, A.; Kolarkar, A.; Kuchina, E.; Kumbartzki, G.; LeRose, J. J.; Lindgren, R.; Liyanage, N.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; Mazouz, M.; Meekins, D.; Michaels, R.; Moffit, B.; Morita, H.; Nanda, S.; Perdrisat, C. F.; Piasetzky, E.; Potokar, M.; Punjabi, V.; Qiang, Y.; Reinhold, J.; Reitz, B.; Ron, G.; Rosner, G.; Ryckebusch, J.; Saha, A.; Sawatzky, B.; Segal, J.; Shahinyan, A.; Širca, S.; Slifer, K.; Solvignon, P.; Sulkosky, V.; Thompson, N.; Ulmer, P. E.; Urciuoli, G. M.; Voutier, E.; Wang, K.; Watson, J. W.; Weinstein, L. B.; Wojtsekhowski, B.; Wood, S.; Yao, H.; Zheng, X.; Zhu, L.

    2014-10-01

    The five-fold differential cross section for the 12C{{(e,{{e}^{\\prime }}p)}^{11}}B reaction was determined over a missing momentum range of 200-400 MeV\\;{{c}^{-1}}, in a kinematics regime with {{x}_{B}}\\gt 1 and {{Q}^{2}}=2.0 {{(GeV\\;{{c}^{-1}})}^{2}}. A comparison of the results with previous lower missing momentum data and with theoretical models are presented. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV\\;{{c}^{-1}}. The theoretical calculations are from two very different approaches, one mean field and the other short range correlated; yet for this system the two approaches show striking agreement with the data and each other up to a missing momentum value of 325 MeV\\;{{c}^{-1}}. For larger momenta, the calculations diverge which is likely due to the factorization approximation used in the short range approach.

  8. A Model of Comet Nucleus Rotation

    NASA Astrophysics Data System (ADS)

    Keller, H. U.; Jorda, L.; Rickman, H.; Thomas, N.

    2000-10-01

    Modelling cometary rotation is of particular interest for the preparation of space missions to comets. For example, the mapping phase during the ROSETTA mission must be planned keeping in mind that, unlike most asteroids, the rotational state of most short-period comets might be complex (excited). The modelling of cometary nucleus rotation can also provide us with important parameters that are needed to interpret coma structures or to build time-dependent thermal models of the nucleus. We combine a general three-dimensional model for the nucleus shape, surface properties, and insolation with a simplified thermal model to calculate the local time-dependent activity and consequently the non-gravitational forces acting on the nucleus. The torque of this force is then used to numerically solve the forced Euler equations for a homogeneously outgassing irregularly-shaped cometary nucleus. We will discuss the results of our model for comets 46P/Wirtanen, the target of the ROSETTA mission, and 19P/Borrelly, the target of DEEP-SPACE 1 and derive some generalized inferences.

  9. An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial (12)C(16)O2 infrared line list.

    PubMed

    Huang, Xinchuan; Schwenke, David W; Tashkun, Sergey A; Lee, Timothy J

    2012-03-28

    An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO(2) by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σ(rms) (root-mean-squares error) = 0.0156 cm(-1) for 6873 J = 0-117 (12)C(16)O(2) experimental energy levels, even though less than 500 (12)C(16)O(2) energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the (12)C(16)O(2) and (13)C(16)O(2) isotopologues, spectroscopic constants G(v) computed from Ames-1 are within ±0.01 and 0.02 cm(-1) of reliable experimentally derived values, while for the (16)O(12)C(18)O, (16)O(12)C(17)O, (16)O(13)C(18)O, (16)O(13)C(17)O, (12)C(18)O(2), (17)O(12)C(18)O, (12)C(17)O(2), (13)C(18)O(2), (13)C(17)O(2), (17)O(13)C(18)O, and (14)C(16)O(2) isotopologues, the differences are between ±0.10 and 0.15 cm(-1). To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initio dipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for (12)C(16)O(2) using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σ(rms)(ΔI) < 20% or σ(rms)(ΔI∕δ(obs)) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra. PMID:22462861

  10. Protein quality control in the nucleus.

    PubMed

    Jones, Ramon D; Gardner, Richard G

    2016-06-01

    The nucleus is the repository for the eukaryotic cell's genetic blueprint, which must be protected from harm to ensure survival. Multiple quality control (QC) pathways operate in the nucleus to maintain the integrity of the DNA, the fidelity of the DNA code during replication, its transcription into mRNA, and the functional structure of the proteins that are required for DNA maintenance, mRNA transcription, and other important nuclear processes. Although we understand a great deal about DNA and RNA QC mechanisms, we know far less about nuclear protein quality control (PQC) mechanisms despite that fact that many human diseases are causally linked to protein misfolding in the nucleus. In this review, we discuss what is known about nuclear PQC and we highlight new questions that have emerged from recent developments in nuclear PQC studies. PMID:27015023

  11. Interpretive monitoring in the caudate nucleus

    PubMed Central

    Yanike, Marianna; Ferrera, Vincent P

    2014-01-01

    In a dynamic environment an organism has to constantly adjust ongoing behavior to adapt to a given context. This process requires continuous monitoring of ongoing behavior to provide its meaningful interpretation. The caudate nucleus is known to have a role in behavioral monitoring, but the nature of these signals during dynamic behavior is still unclear. We recorded neuronal activity in the caudate nucleus in monkeys during categorization behavior that changed rapidly across contexts. We found that neuronal activity maintained representation of the identity and context of a recently categorized stimulus, as well as interpreted the behavioral meaningfulness of the maintained trace. The accuracy of this cognitive monitoring signal was highest for behavior for which subjects were prone to make errors. Thus, the caudate nucleus provides interpretive monitoring of ongoing behavior, which is necessary for contextually specific decisions to adapt to rapidly changing conditions. DOI: http://dx.doi.org/10.7554/eLife.03727.001 PMID:25415238

  12. Uncovering the Nucleus Candidate for NGC 253

    NASA Astrophysics Data System (ADS)

    Günthardt, G. I.; Agüero, M. P.; Camperi, J. A.; Díaz, R. J.; Gomez, P. L.; Bosch, G.; Schirmer, M.

    2015-11-01

    NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H2 rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this

  13. Sigma-nucleus potential in A=28.

    PubMed

    Noumi, H; Saha, P K; Abe, D; Ajimura, S; Aoki, K; Bhang, H C; Endo, T; Fujii, Y; Fukuda, T; Guo, H C; Imai, K; Hashimoto, O; Hotchi, H; Kim, E H; Kim, J H; Kishimoto, T; Krutenkova, A; Maeda, K; Nagae, T; Nakamura, M; Outa, H; Sekimoto, M; Saito, T; Sakaguchi, A; Sato, Y; Sawafta, R; Shimizu, Y; Takahashi, T; Tang, L; Tamura, H; Tanida, K; Watanabe, T; Xia, H H; Zhou, S H; Zhu, L H; Zhu, X F

    2002-08-12

    We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum. PMID:12190516

  14. Nucleus model for periodic Comet Tempel 2

    NASA Technical Reports Server (NTRS)

    Sekanina, Zdenek

    1991-01-01

    Observational data obtained primarily during 1988 are analyzed and synthesized to develop a comprehensive physical model for the nucleus of Periodic Comet Tempel 2, one of the best studied members of Jupiter's family of short-period comets. It is confirmed that a previous investigation provided reliable information on the comet's spin-axis orientation, which implies and obliquity of 54 degrees of the orbit plane to the equatorial plane and which appears to have varied little - if at all - with time. This conclusion is critical for fitting a triaxial ellipsoid to approximate the figure of the nucleus.

  15. Hydrated nucleus pulposus herniation in seven dogs.

    PubMed

    Manunta, M L; Evangelisti, M A; Bergknut, N; Grinwis, G C M; Ballocco, I; Meij, B P

    2015-03-01

    The clinical signs, magnetic resonance imaging (MRI) findings, treatment and follow-up in seven dogs with hydrated nucleus pulposus extrusion (HNPE) are reported. All dogs had tetraparesis or tetraplegia. T2-weighted MRI revealed extradural hyperintense homogeneous material compressing the cervical spinal cord. After conservative treatment (five dogs) or surgical decompression (two dogs), all dogs returned to ambulatory function within 1 month. Follow-up MRI in conservatively treated dogs revealed complete disappearance of the extruded material. Histopathological examination of surgical specimens confirmed that the retrieved material was extruded nucleus pulposus with evidence of early degeneration. PMID:25599897

  16. Energy loss effect on color center creation in LiF crystals under irradiation with 12C, 14N, 40Ar, 84Kr, and 130Xe ions

    NASA Astrophysics Data System (ADS)

    Dauletbekova, A.; Schwartz, K.; Sorokin, M. V.; Baizhumanov, M.; Akilbekov, A.; Zdorovets, M.

    2015-09-01

    Color center creation in LiF crystals irradiated with 12C, 14N, 40Ar, 84Kr, and 130Xe MeV ions were studied as a function of the absorbed energy (fluence). For light ions (12C, 14N) the saturation of single F centers takes place at higher absorbed energy (5 × 1023 eV/cm3) than that for 40Ar, 84Kr and 130Xe ions (∼1023 eV/cm3). The saturation concentration of F centers for 12C and 14N (2 × 1019 cm-3) is twice of that for the heavier ions. Further irradiation with light ions decreases concentration of F centers, presumably due to aggregation, whereas for heavy ions the saturation concentration remains approximately the same that can be explained by much stronger recombination losses within single tracks.

  17. Monitoring the irradiation field of 12C and 16O SOBP beams using positron emitters produced through projectile fragmentation reactions

    NASA Astrophysics Data System (ADS)

    Inaniwa, Taku; Kohno, Toshiyuki; Tomitani, Takehiro; Sato, Shinji

    2008-02-01

    In order to effectively utilize the prominent properties of heavy ions in radiotherapy, it is important to evaluate both the position of the field irradiated with incident ions and the absorbed dose distribution in a patient's body. One of the methods for this purpose is the utilization of the positron emitters produced through the projectile fragmentation reactions of stable heavy ions with target nuclei. In heavy-ion therapy, spread-out Bragg peak (SOBP) beams are used to achieve uniform biological dose distributions in the whole tumor volume. Therefore, in this study, we designed SOBP beams of 30 and 50 mm water-equivalent length (mmWEL) in width for 12C and 16O, and carried out irradiation experiments using them. Water, polyethylene and polymethyl methacrylate were selected as targets to simulate a human body. Pairs of annihilation gamma rays were detected by means of a limited-angle positron camera for 500 s, and annihilation gamma-ray distributions were obtained. The maximum likelihood estimation (MLE) method was applied to the detected distributions for evaluating the positions of the distal and proximal edges of the SOBP in a target. The differences between the positions evaluated with the MLE method and those derived from the measured dose distributions were less than 1.7 mm and 2.5 mm for the distal and the proximal edge, respectively, in all irradiation conditions. When the positions of both edges are determined with the MLE method, the most probable shape of the dose distribution in a target can be estimated simultaneously. The close agreement between the estimated and the measured distributions implied that the shape of the dose distribution in an irradiated target could be evaluated from the detected annihilation gamma-ray distribution.

  18. Evaluated cross-section libraries and kerma factors for neutrons up to 100 MeV on {sup 12}C

    SciTech Connect

    Chadwick, M.B.; Blann, M.; Cox, L.; Young, P.G.; Meigooni, A.

    1995-04-11

    A program is being carried out at Lawrence Livermore National Laboratory to develop high-energy evaluated nuclear data libraries for use in Monte Carlo simulations of cancer radiation therapy. In this report we describe evaluated cross sections and kerma factors for neutrons with incident energies up to 100 MeV on {sup 12}C. The aim of this effort is to incorporate advanced nuclear physics modeling methods, with new experimental measurements, to generate cross section libraries needed for an accurate simulation of dose deposition in fast neutron therapy. The evaluated libraries are based mainly on nuclear model calculations, benchmarked to experimental measurements where they exist. We use the GNASH code system, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms. The libraries tabulate elastic and nonelastic cross sections, angle-energy correlated production spectra for light ejectiles with A{le}and kinetic energies given to light ejectiles and heavy recoil fragments. The major steps involved in this effort are: (1) development and validation of nuclear models for incident energies up to 100 MeV; (2) collation of experimental measurements, including new results from Louvain-la-Nueve and Los Alamos; (3) extension of the Livermore ENDL formats for representing high-energy data; (4) calculation and evaluation of nuclear data; and (5) validation of the libraries. We describe the evaluations in detail, with particular emphasis on our new high-energy modeling developments. Our evaluations agree well with experimental measurements of integrated and differential cross sections. We compare our results with the recent ENDF/B-VI evaluation which extends up to 32 MeV.

  19. (C-12)/(C-13) isotope ratio in the local interstellar medium from observations of (C-13)(O-18) in molecular clouds

    NASA Technical Reports Server (NTRS)

    Langer, William D.; Penzias, Arno A.

    1993-01-01

    The paper examines the (C-12)/(C-13) isotope ratio in the solar neighborhood on the basis of observations of the (C-12)(O-18) and (C-13)(O-18) J = 1-0 transitions in four interstellar clouds located within 500 pc. The (C-12)/(C-13) ratio in these sources ranges from 57 to 74, and its weighted average is 62 +/- 4, with thermal noise and line formation uncertainties contributing about equally to the probable error. These values indicate moderate chemical evolution in the local star neighborhood since the formation of the solar system, in good agreement with model prediction of the current carbon ratio in the local interstellar medium.

  20. Projections of the sensory trigeminal nucleus in a percomorph teleost, tilapia (Oreochromis niloticus).

    PubMed

    Xue, Hao-Gang; Yamamoto, Naoyuki; Yang, Chun-Ying; Kerem, Gulnisa; Yoshimoto, Masami; Sawai, Nobuhiko; Ito, Hironobu; Ozawa, Hitoshi

    2006-03-20

    The sensory trigeminal nucleus of teleosts is the rostralmost nucleus among the trigeminal sensory nuclear group in the rhombencephalon. The sensory trigeminal nucleus is known to receive the somatosensory afferents of the ophthalmic, maxillar, and mandibular nerves. However, the central connections of the sensory trigeminal nucleus remain unclear. Efferents of the sensory trigeminal nucleus were examined by means of tract-tracing methods, in a percomorph teleost, tilapia. After tracer injections to the sensory trigeminal nucleus, labeled terminals were seen bilaterally in the ventromedial thalamic nucleus, periventricular pretectal nucleus, medial part of preglomerular nucleus, stratum album centrale of the optic tectum, ventrolateral nucleus of the semicircular torus, lateral valvular nucleus, prethalamic nucleus, tegmentoterminal nucleus, and superior and inferior reticular formation, with preference for the contralateral side. Labeled terminals were also found bilaterally in the oculomotor nucleus, trochlear nucleus, trigeminal motor nucleus, facial motor nucleus, facial lobe, descending trigeminal nucleus, medial funicular nucleus, and contralateral sensory trigeminal nucleus and inferior olive. Labeled terminals in the oculomotor nucleus and trochlear nucleus showed similar densities on both sides of the brain. However, labelings in the trigeminal motor nucleus, facial motor nucleus, facial lobe, descending trigeminal nucleus, and medial funicular nucleus showed a clear ipsilateral dominance. Reciprocal tracer injection experiments to the ventromedial thalamic nucleus, optic tectum, and semicircular torus resulted in labeled cell bodies in the sensory trigeminal nucleus, with a few also in the descending trigeminal nucleus. PMID:16440296

  1. Nucleus-nucleus interactions between 20 and 65 GeV per nucleon

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Derrickson, J. H.; Fountain, W. F.; Meegan, C. A.; Parnell, T. A.; Roberts, F. E.; Watts, J. W.; Oda, H.; Takahashi, Y.; Jones, W. V.

    1987-01-01

    A hybrid electronic-counter/emulsion-chamber instrument was exposed to high-energy cosmic rays on a balloon. The data on 105 nucleus-nucleus collisions in the energy range 20-65 GeV/nucleon and for incident nuclear charges Zp in the range of 22 to 28 are presented. Inclusive characteristics of particle production on different targets (plastic, emulsion, and lead) are shown and compared with models based on the superposition of nucleon-nucleus interactions. Features of a subset of the more central collisions with a plastic target and some characteristics of individual events with the highest multiplicity of produced particles are described.

  2. Compound nucleus studies withy reverse kinematics

    SciTech Connect

    Moretto, L.G.

    1985-06-01

    Reverse kinematics reactions are used to demonstrate the compound nucleus origin of intermediate mass particles at low energies and the extension of the same mechanism at higher energies. No evidence has appeared in our energy range for liquid-vapor equilibrium or cold fragmentation mechanisms. 11 refs., 12 figs.

  3. Coherent elastic neutrino-nucleus scattering

    NASA Astrophysics Data System (ADS)

    Scholberg, Kate

    2015-05-01

    I describe physics potential and experimental prospects for coherent elastic neutrino-nucleus scattering (CEvNS), a process which has not yet been observed. Germanium- based detectors represent a promising technology for CEvNS experiments. I focus primarily on stopped-pion neutrino sources.

  4. Transport model of nucleon-nucleus reaction

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Townsend, L. W.; Cucinotta, F. A.

    1986-01-01

    A simplified model of nucleon-nucleus reaction is developed and some of its properties are examined. Comparisons with proton production measured for targets of Al-27, Ni-58, Zr-90, and Bi-209 show some hope for developing an accurate model for these complex reactions. It is suggested that binding effects are the next step required for further development.

  5. The Checkerboard Model of the Nucleus

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2015-04-01

    The Checker Board Model (CBM) of the nucleus and the associated extended standard model predicts that nature has 5 generations of quarks not 3 and that Nucleus is 2 dimensional. The CBM theory began with an insight into the structure of the He nucleus around the year 1989. Details of how this theory evolved which took many years, and is found on my web site (http://checkerboard.dnsalias.net) or in the following references One independent check of this model is that the wavelength of the ``up'' quark orbiting inside the proton at 84.8123% the speed of light (around the ``dn'' quark in the center of the proton) turns out to be exactly one de Broglie wavelength something determined after the mass and speed of the up quark were determined by other means. This theory explains the mass of the proton and neutron and their magnetic moments and this along with the beautiful symmetric 2D structure of the He nucleus led to the evolution of this theory. When this theory was first presented at Argonne in 1996, it was the first time that anyone had predicted the quarks orbited inside the proton at relativistic speeds and it was met with skepticism.

  6. The Nucleus and the Simple Microscope.

    ERIC Educational Resources Information Center

    Ford, Brian J.

    1982-01-01

    The 150th anniversary of the naming of the nucleus by Robert Brown in 1831 was commemorated by re-creating some of his most important observations using two of his microscopes. Comments on Brown's career and the microtechnique employed during his time are provided. (Author/JN)

  7. Nucleon-nucleus interactions from JACEE

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1985-01-01

    Results on hadron-nucleus interactions from the Japanese-American Cooperation Emulsion Experiment experiment are presented. Angular distributions for charged particles, and angular and transverse momentum spectra for photons have been measured for a sample of events with sigma epsilon sub gamma. Results on central rapidity density and transverse energy flow are discussed.

  8. Crystal and molecular structures of benzo[4,5]imidazo[1,2-c]quinazolin-6-one and 10-carboxybenzo[4,5]imidazo[1,2-c]quinazolin-6-one: A quantum-chemical study of their tautomerism

    SciTech Connect

    Koval'chukova, O. V.; Stash, A. I.; Strashnov, P. V.; Neborak, E. V.; Strashnova, S. B.; Zaitsev, B. E.

    2011-03-15

    Benzo[4,5]imidazo[1,2-c]quinazolin-6-one and 10-carboxybenzo[4,5]imidazo[1,2-c]quinazolin-6-one were isolated in the crystalline state and studied by X-ray diffraction. The crystal and molecular structures of these compounds were determined by X-ray diffraction. The energy characteristics of the tautomeric and ionic forms were calculated by the quantum-chemical PM3 method.

  9. Heavy-flavour dynamics in proton-proton and nucleus-nucleus collisions at LHC

    NASA Astrophysics Data System (ADS)

    Nardi, M.; Beraudo, A.; De Pace, A.; Monteno, M.; Prino, F.

    2016-01-01

    We present recent results for heavy-quark observables in nucleus-nucleus collisions at LHC energies, obtained by the POWLANG transport setup. The initial creation of c c ¯ and b b ¯ pairs is simulated with a perturbative QCD approach (POWHEG+PYTHIA) and validated through comparison to experimental data of proton-proton collisions. In the nucleus-nucleus case, the propagation of the heavy quarks in the plasma is studied with the relativistic Langevin equation, here solved using weak-coupling transport-coefficients. Successively, the heavy quarks hadronize in the medium. We compute the nuclear modification factor RAA and the elliptic flow v2 of the final D mesons, as well as D - h correlations, and compare our results to experimental data from the ALICE and CMS Collaborations.

  10. Average transverse momentum and energy density in high-energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1986-01-01

    Emulsion chambers were used to measure the transverse momenta of photons or pi(0) mesons produced in high-energy cosmic-ray nucleus-nucleus collisions. A group of events having large average transverse momenta has been found which apparently exceeds the expected limiting values. Analysis of the events at early interaction times, of the order of 1 fm/c, indicates that the observed transverse momentum increases with both rapidity density and energy density.

  11. Results on ultra-relativistic nucleus-nucleus interactions from balloon-borne emulsion chambers

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Derrickson, J. H.; Fountain, W.; Meegan, C. A.; Takahashi, Y.; Watts, J. W.; Fuki, M.; Gregory, J. C.; Hayashi, T.

    1985-01-01

    The results of balloon-borne emulsion-chamber measurements on high-energy cosmic-ray nuclei (Burnett et al., 1983) are summarized in tables and graphs and briefly characterized. Special consideration is given to seven nucleus-nucleus interaction events at energy in excess of 1 TeV/A with multiplicity greater than 400, and to Fe interactions (53 with CHO, 10 with emulsion, and 14 with Pb) at 20-60 GeV/A.

  12. Draft Genome Sequences of Listeria monocytogenes Serotype 4b Strains 944 and 2993 and Serotype 1/2c Strains 198 and 2932.

    PubMed

    Casey, Aidan; McAuliffe, Olivia; Fox, Edward M; Leong, Dara; Gahan, Cormac G M; Jordan, Kieran

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen and the causative agent of listeriosis among humans and animals. The draft genome sequences of L. monocytogenes serotype 4b strains 944 and 2993 and serotype 1/2c strains 198 and 2932 are reported here. PMID:27257200

  13. Complete and incomplete fusion in the [sup 28]Si+[sup 12]C, [sup 13]C reactions around 5 MeV/nucleon

    SciTech Connect

    Arena, N.; Cavallaro, S.; Femino', S.; Figuera, P.; Pirrone, S.; Politi, G.; Porto, F.; Romano, S.; Sambataro, S. )

    1994-08-01

    Velocity spectra, angular, and mass distributions of the evaporation residues produced in the reaction [sup 28]Si+[sup 12]C at [ital E]([sup 28]Si)=104, 115, and 154 MeV have been measured in the angular range 2.5[degree][le][var theta][sub [ital L

  14. Identification of high-risk Listeria monocytogenes serotypes in lineage I (serotype 1/2a, 1/2c, 3a and 3c) using multiplex PCR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: Using molecular subtyping techniques, Listeria monocytogenes is divided into three major phylogenetic lineages, and a multiplex PCR method can differentiate five L. monocytogenes subgroups: 1/2a-3a, 1/2c-3c, 1/2b-3b-7, 4b-4d-4e, and 4a-4c. In the current study, we conducted genome comparison...

  15. Draft Genome Sequences of Listeria monocytogenes Serotype 4b Strains 944 and 2993 and Serotype 1/2c Strains 198 and 2932

    PubMed Central

    Casey, Aidan; Fox, Edward M.; Leong, Dara; Gahan, Cormac G. M.; Jordan, Kieran

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen and the causative agent of listeriosis among humans and animals. The draft genome sequences of L. monocytogenes serotype 4b strains 944 and 2993 and serotype 1/2c strains 198 and 2932 are reported here. PMID:27257200

  16. The effect of microdosimetric 12C6+ heavy ion irradiation and Mg2+ on canthaxanthin production in a novel strain of Dietzia natronolimnaea

    PubMed Central

    2013-01-01

    Background Dietzia natronolimnaea is one of the most important bacterial bioresources for high efficiency canthaxanthin production. It produces the robust and stable pigment canthaxanthin, which is of special interest for the development of integrated biorefineries. Mutagenesis employing 12C6+ irradiation is a novel technique commonly used to improve microorganism productivity. This study presents a promising route to obtaining the highest feasible levels of biomass dry weight (BDW), and total canthaxanthin by using a microdosimetric model of 12C6+ irradiation mutation in combination with the optimization of nutrient medium components. Results This work characterized the rate of both lethal and non-lethal dose mutations for 12C6+ irradiation and the microdosimetric kinetic model using the model organism, D. natronolimnaea svgcc1.2736. Irradiation with 12C6+ ions resulted in enhanced production of canthaxanthin, and is therefore an effective method for strain improvement of D. natronolimnaea svgcc1.2736. Based on these results an optimal dose of 0.5–4.5 Gy, Linear energy transfer (LET) of 80 keV μm-1and energy of 60 MeV u-1 for 12C6+ irradiation are ideal for optimum and specific production of canthaxanthin in the bacterium. Second-order empirical calculations displaying high R-squared (0.996) values between the responses and independent variables were derived from validation experiments using response surface methodology. The highest canthaxanthin yield (8.14 mg) was obtained with an optimized growth medium containing 21.5 g L-1 D-glucose, 23.5 g L-1 mannose and 25 ppm Mg2+ in 1 L with an irradiation dose of 4.5 Gy. Conclusions The microdosimetric 12C6+ irradiation model was an effective mutagenic technique for the strain improvement of D. natronolimnaea svgcc1.2736 specifically for enhanced canthaxanthin production. At the very least, random mutagenesis methods using 12C6+ions can be used as a first step in a combined approach with long-term continuous

  17. Applicability of fluid-dynamical modeling of nucleus-nucleus collisions at relativistic energies

    NASA Astrophysics Data System (ADS)

    Hazineh, Dean; Auvinen, Jussi; Nahrgang, Marlene; Bass, Steffen

    2015-10-01

    At sufficiently high temperatures and densities, similar to the conditions found in the early universe, QCD matter forms a deconfined state called the quark gluon plasma (QGP). This state of matter can be created in collisions of ultra-relativistic heavy-ions, and RHIC data suggests that this QGP behaves similar to an ideal fluid. Viscous relativistic fluid dynamics therefore is one of the preferred theoretical tools to model the time-evolution and properties of the QGP. As the collision energy or the system size is decreased, the range of applicability of viscous fluid dynamics becomes smaller as the length scale of the interaction among the basic constituents is similar to the overall scale of the collision system itself. In order to investigate the validity of fluid-dynamical modeling of proton-nucleus and nucleus-nucleus collisions at LHC and RHIC, we conduct an analysis of the spatial and temporal evolution of the Knudsen number, i.e. the ratio of the microscopic mean free path to the macroscopic length scale of the system. We show results for large and small collision systems, as a function of the specific shear viscosity, and discuss the range of applicability of fluid-dynamical modeling in relativistic proton-nucleus and nucleus-nucleus collisions at different energies.

  18. Nucleus-nucleus total reaction cross sections, and the nuclear interaction radius

    SciTech Connect

    Abu-Ibrahim, Badawy

    2011-04-15

    We study the nucleus-nucleus total reaction cross sections for stable nuclei, in the energy region from 30A MeV to about 1A GeV, and find them to be in proportion to ({radical}({sigma}{sub pp}{sup tot}Z{sub 1}{sup 2/3}+{sigma}{sub pn}{sup tot}N{sub 1}{sup 2/3})+{radical}({sigma}{sub pp}{sup tot}Z{sub 2}{sup 2/3}+{sigma}{sub pn}{sup tot}N{sub 2}{sup 2/3})) {sup 2} in the mass range 8 to 100. Also, we find a parameter-free relation that enables us to predict a total reaction cross section for any nucleus-nucleus within 10% uncertainty at most, using the experimental value of the total reaction cross section of a given nucleus-nucleus. The power of the relation is demonstrated by several examples. The energy dependence of the nuclear interaction radius is deduced; it is found to be almost constant in the energy range from about 200A MeV to about 1A GeV; in this energy range and for nuclei with N=Z, R{sub I}(A)=(1.14{+-}0.02)A{sup 1/3} fm.

  19. Collateral projections from the lateral parabrachial nucleus to the paraventricular thalamic nucleus and the central amygdaloid nucleus in the rat.

    PubMed

    Liang, Shao-Hua; Yin, Jun-Bin; Sun, Yi; Bai, Yang; Zhou, Kai-Xiang; Zhao, Wen-Jun; Wang, Wei; Dong, Yu-Lin; Li, Yun-Qing

    2016-08-26

    Combined the retrograde double tracing with immunofluorescence histochemical staining, we examined the neurons in the lateral parabrachial nucleus (LPB) sent collateral projections to the paraventricular thalamic nucleus (PVT) and central amygdaloid nucleus (CeA) and their roles in the nociceptive transmission in the rat. After the injection of Fluoro-gold (FG) into the PVT and tetramethylrhodamine-dextran (TMR) into the CeA, respectively, FG/TMR double-labeled neurons were observed in the LPB. The percentages of FG/TMR double-labeled neurons to the total number of FG- or TMR-labeled neurons were 6.18% and 9.09%, respectively. Almost all of the FG/TMR double-labeled neurons (95%) exhibited calcitonin gene-related peptide (CGRP) immunoreactivity. In the condition of neuropathic pain, 94% of these neurons showed FOS immunoreactivity. The present data indicates that some of CGRP-expressing neurons in the LPB may transmit nociceptive information toward the PVT and CeA by way of axon collaterals. PMID:27423318

  20. Dropped nucleus following phacoemulsification cataract surgery.

    PubMed

    Tajunisah, I; Reddy, S C

    2007-12-01

    Twenty two cases of dropped nucleus following 1,196 phacoemulsification procedures in cataract surgery were examined retrospectively to determine the incidence, predisposing factors and visual outcomes of this dreaded complication. All the cases underwent pars plana vitrectomy and the lens fragments were removed with phacofragmotome, vitrectomy cutter or delivered through limbus. The incidence of dropped nucleus was 1.84%. The predisposing factors were hard cataracts (13.6%), polar cataracts (9.1%), previously vitrectomized eyes (4.5%) and high myopia (4.5%). The final visual outcome was > or = 6/12 in 10 eyes (45.5%); complications were seen in 5 eyes (22.7%). The interval between initial surgery and vitrectomy, the method of fragment removal and the type of lens implanted, did not influence the final visual outcome. PMID:18705466

  1. Cell Nucleus-Targeting Zwitterionic Carbon Dots

    PubMed Central

    Jung, Yun Kyung; Shin, Eeseul; Kim, Byeong-Su

    2015-01-01

    An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation. PMID:26689549

  2. Macromolecular transport in synapse to nucleus communication.

    PubMed

    Panayotis, Nicolas; Karpova, Anna; Kreutz, Michael R; Fainzilber, Mike

    2015-02-01

    Local signaling events at synapses or axon terminals must be communicated to the nucleus to elicit transcriptional responses. The lengths of neuronal processes pose a significant challenge for such intracellular communication. This challenge is met by mechanisms ranging from rapid signals encoded in calcium waves to slower macromolecular signaling complexes carried by molecular motors. Here we summarize recent findings on macromolecular signaling from the synapse to the nucleus, in comparison to those employed in injury signaling along axons. A number of common themes emerge, including combinatorial signal encoding by post-translational mechanisms such as differential phosphorylation and proteolysis, and conserved roles for importins in coordinating signaling complexes. Neurons may integrate ionic flux with motor-transported signals as a temporal code for synaptic plasticity signaling. PMID:25534890

  3. Core-nucleus distortation in hypernuclei

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We are completing a study of the effects of the spherical distortion of the {open_quotes}core{close_quotes} nucleus by the {Lambda} in a hypernucleus. The response of the core was determined by an appropriately chosen energy-density functional which depends, in particular, on the nuclear compressibility. The forcing action of the A is determined by the nuclear density dependence of the {Lambda} binding in nuclear matter which is obtained from our work on the {Lambda} single-particle energies. Because of the strongly repulsive {Lambda}NN forces, this {Lambda} binding {open_quotes}saturates{close_quotes} at a density close to the central density of nuclei, and results in a reduced core-nucleus distortion much less than would otherwise be obtained. The effects of the core distortion then turn out to be very small even for quite light hypernuclei. This result justifies the assumption that spherical core nuclei are effectively undistorted in a hypernucleus.

  4. Coherency in neutrino-nucleus elastic scattering

    NASA Astrophysics Data System (ADS)

    Kerman, S.; Sharma, V.; Deniz, M.; Wong, H. T.; Chen, J.-W.; Li, H. B.; Lin, S. T.; Liu, C.-P.; Yue, Q.; Texono Collaboration

    2016-06-01

    Neutrino-nucleus elastic scattering provides a unique laboratory to study the quantum mechanical coherency effects in electroweak interactions, towards which several experimental programs are being actively pursued. We report results of our quantitative studies on the transitions towards decoherency. A parameter (α ) is identified to describe the degree of coherency, and its variations with incoming neutrino energy, detector threshold, and target nucleus are studied. The ranges of α that can be probed with realistic neutrino experiments are derived, indicating complementarity between projects with different sources and targets. Uncertainties in nuclear physics and in α would constrain sensitivities in probing physics beyond the standard model. The maximum neutrino energies corresponding to α >0.95 are derived.

  5. Finite nucleus effects on relativistic energy corrections

    NASA Technical Reports Server (NTRS)

    Dyall, Kenneth G.; Faegri, Knut, Jr.

    1993-01-01

    The effect of using a finite nucleus model in quantum-chemical calculations is examined. Relativistic corrections from the first order Foldy-Wouthuysen terms are affected indirectly by the change in wavefunction, but also directly as a result of revised expressions for the Darwin and spin-orbit terms due to the change in nuclear potential. A calculation for the Rn atom indicates that the mass-velocity and Darwin corrections are much more sensitive to the finite nucleus than the non-relativistic total energy, but that the total contribution for these two terms is quite stable provided the revised form of the Darwin term is used. The spin-orbit interaction is not greatly affected by the choice of nuclear model.

  6. Neurofibromin is actively transported to the nucleus.

    PubMed

    Vandenbroucke, Ina; Van Oostveldt, Patrick; Coene, Elisabeth; De Paepe, Anne; Messiaen, Ludwine

    2004-02-27

    Mutations in the neurofibromatosis type 1 (NF1) tumor suppressor gene predispose individuals to a variety of benign and malignant tumors. Many tumor suppressors 'shuttle' between the nucleus and the cytoplasm, thus regulating their function. By expressing different NF1 constructs in COS-7 cells (encompassing exons 28-49 and fused to the green fluorescent protein), we identified a functional nuclear localization signal (NLS) in exon 43. Mutation of the NLS completely abolishes the nuclear entry of the NF1-derivative fusion protein. A highly expressed splice variant that lacks this NLS controls the localization and hence the function of neurofibromin. The localization of neurofibromin in the nucleus may provide novel clues to unknown functions for NF1. PMID:14988005

  7. Angular distributions of target fragments from the reactions of 292 MeV - 25. 2 GeV /sup 12/C with /sup 197/Au and /sup 238/U

    SciTech Connect

    Morita, Y.

    1983-05-20

    Angular distributions of target fragments from the reactions of /sup 12/C with /sup 197/Au and /sup 238/U were measured at projectile energies of 292 MeV, 1.0 GeV, 3.0 GeV, 12.0 GeV and 25.2 GeV. The angular distributions of the /sup 197/Au target fragments were all forwardly peaked. Extensively forward peaked angular distributions were observed at the non-relativistic projectile energies (292 MeV, 1.0 GeV). No obvious differences were observed in the angular distributions at the different relativistic projectile energies of 3.0 GeV, 12.0 GeV and 25.2 GeV. The characteristic angular distribution pattern from the relativistic projectile energy experiments was also observed in the non-relativistic energy experiments. Maximum degree of forward-peaking in the angular distributions at each projectile energy was observed at the product mass number (A) around 190 from the 292 MeV projectile energy, at A=180 from 1.0 GeV and at A=175 from 3.0 GeV and 12.0 GeV. In general, two different types of angular distributions were observed in the relativistic projectile energy experiments with the /sup 238/U target. Isotropic angular distributions were observed for the fission product nuclides. The angular distributions of the fission products at the intermediate (292 MeV) energy showed slightly forward- peaked angular distributions. Because of the long projectile-target interaction time in the primary nuclear reaction, larger momentum was transferred from the projectile to the target nucleus. Steep forward-peaked angular distributions were also observed with the /sup 238/U target.

  8. Revisiting the supratrigeminal nucleus in the rat.

    PubMed

    Fujio, T; Sato, F; Tachibana, Y; Kato, T; Tomita, A; Higashiyama, K; Ono, T; Maeda, Y; Yoshida, A

    2016-06-01

    The supratrigeminal nucleus (Vsup), originally proposed as a premotoneuron pool in the trigeminal reflex arc, is a key structure of jaw movement control. Surprisingly, however, the location of the rat Vsup has not precisely been defined. In light of our previous cat studies, we made two hypotheses regarding the rat Vsup: (1) the Vsup is cytoarchitectonically distinguishable from its surrounding structures; (2) the Vsup receives central axon terminals of the trigeminal mesencephalic nucleus (Vmes) neurons which are primary afferents innervating muscle spindles of jaw-closing muscles and periodontal ligaments around the teeth. To test the first hypothesis, we examined the cytoarchitecture of the rat Vsup. The Vsup was identified as an area medially adjacent to the dorsomedial part of trigeminal principal sensory nucleus (Vp), and extended from the level just rostral to the caudal two-thirds of the trigeminal motor nucleus (Vmo) to the level approximately 150μm caudal to the Vmo. Our rat Vsup was much smaller and its location was considerably different in comparison to the Vsup reported previously. To evaluate the second hypothesis, we tested the distribution patterns of Vmes primary afferent terminals in the cytoarchitectonically identified Vsup. After transganglionic tracer applications to the masseter, deep temporal, and medial pterygoid nerves, a large number of axon terminals were observed in all parts of Vsup (especially in its medial part). After applications to the inferior alveolar, infraorbital, and lingual nerves, a small number of axon terminals were labeled in the caudolateral Vsup. The Vsup could also be identified electrophysiologically. After electrical stimulation of the masseter nerve, evoked potentials with slow negative component were isolated only in the Vsup. The present findings suggest that the rat Vsup can be cytoarchitectonically and electrophysiologically identified, receives somatotopic termination of the trigeminal primary afferents, and

  9. Physical Properties of Cometary Nucleus Candidates

    NASA Technical Reports Server (NTRS)

    Jewitt, David; Hillman, John (Technical Monitor)

    2003-01-01

    In this proposal we aim to study the physical properties of the Centaurs and the dead comets, these being the precursors to, and the remnants from, the active cometary nuclei. The nuclei themselves are very difficult to study, because of the contaminating effects of near-nucleus coma. Systematic investigation of the nuclei both before they enter the zone of strong sublimation and after they have depleted their near-surface volatiles should neatly bracket the properties of these objects, revealing evolutionary effects.

  10. Development of a Mobile Ice Nucleus Counter

    SciTech Connect

    Kok, Gregory; Kulkarni, Gourihar

    2014-07-10

    An ice nucleus counter has been constructed. The instrument uses built-in refrigeration systems for wall cooling. A cascade refrigeration system will allow the cold wall to operate as low as -70 deg C, and a single stage system can operate the warm wall at -45 deg C. A unique optical particle counter has been constructed using polarization detection of the scattered light. This allows differentiation of the particles exiting the chamber to determine if they are ice or liquid.

  11. The fast Ice Nucleus chamber FINCH

    NASA Astrophysics Data System (ADS)

    Bundke, U.; Nillius, B.; Jaenicke, R.; Wetter, T.; Klein, H.; Bingemer, H.

    2008-11-01

    We present first results of our new developed Ice Nucleus (IN) counter FINCH from the sixth Cloud and Aerosol Characterization Experiment (CLACE 6) campaign at Jungfraujoch station, 3571 m asl. Measurements were made at the total and the ICE CVI inlet. Laboratory measurements of ice onset temperatures by FINCH are compared to those of the static diffusion chamber FRIDGE (FRankfurt Ice Deposition Freezing Experiment). Within the errors of both new instruments the results compare well to published data.

  12. Parity violation in the compound nucleus

    SciTech Connect

    Mitchell, G. E.; Crawford, B. E.; Grossmann, C. A.; Lowie, L. Y.; Bowman, J. D.; Knudson, J.; Penttilae, S.; Seestrom, S. J.; Smith, D. A.; Yen, Yi-Fen; Yuan, V. W.; Delheij, P. P. J.; Haseyama, T.; Masaike, A.; Matsuda, Y.; Postma, H.; Roberson, N. R.; Sharapov, E. I.; Stephenson, S. L.

    1999-06-10

    Measurements have been performed on the helicity dependence of the neutron resonance cross section for many nuclei by our TRIPLE Collaboration. A large number of parity violations are observed. Generic enhancements amplify the signal for symmetry breaking and the stochastic properties of the compound nucleus permit the strength of the symmetry-breaking interaction to be determined without knowledge of the wave functions of individual states. A total of 15 nuclei have been analyzed with this statistical approach. The results are summarized.

  13. Comet nucleus impact probe feasibility study

    NASA Technical Reports Server (NTRS)

    Castro, A. J.

    1980-01-01

    A top level listing of the comet nucleus impact probe (CNIP) feasibility experiments requirements are presented. A conceptual configuration which shows that the feasibility of engineering the experiment is possible and describes the candidate hardware is discussed. The design studies required in order to design the operating experiment are outlined. An overview of a program plan used to estimate a rough order of magnitude cost for the CNIP experiment is given.

  14. Comet nucleus and asteroid sample return missions

    NASA Astrophysics Data System (ADS)

    1992-06-01

    Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.

  15. Comet nucleus and asteroid sample return missions

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.

  16. Efficient nucleus detector in histopathology images.

    PubMed

    Vink, J P; Van Leeuwen, M B; Van Deurzen, C H M; De Haan, G

    2013-02-01

    In traditional cancer diagnosis, (histo)pathological images of biopsy samples are visually analysed by pathologists. However, this judgment is subjective and leads to variability among pathologists. Digital scanners may enable automated objective assessment, improved quality and reduced throughput time. Nucleus detection is seen as the corner stone for a range of applications in automated assessment of (histo)pathological images. In this paper, we propose an efficient nucleus detector designed with machine learning. We applied colour deconvolution to reconstruct each applied stain. Next, we constructed a large feature set and modified AdaBoost to create two detectors, focused on different characteristics in appearance of nuclei. The proposed modification of AdaBoost enables inclusion of the computational cost of each feature during selection, thus improving the computational efficiency of the resulting detectors. The outputs of the two detectors are merged by a globally optimal active contour algorithm to refine the border of the detected nuclei. With a detection rate of 95% (on average 58 incorrectly found objects per field-of-view) based on 51 field-of-view images of Her2 immunohistochemistry stained breast tissue and a complete analysis in 1 s per field-of-view, our nucleus detector shows good performance and could enable a range of applications in automated assessment of (histo)pathological images. PMID:23252774

  17. The nucleus basalis in Huntington's disease.

    PubMed

    Clark, A W; Parhad, I M; Folstein, S E; Whitehouse, P J; Hedreen, J C; Price, D L; Chase, G A

    1983-10-01

    The nucleus basalis of Meynert (nbM) provides most of the cholinergic input to the cerebral cortex. The loss of cortical choline acetyltransferase (CAT) activity in Alzheimer's disease (AD) and senile dementia of the Alzheimer's type (SDAT) appears to be related to a severe depopulation of the nbM in this dementia. In Huntington's disease (HD), by contrast, there is no loss of cortical CAT activity. The present quantitative study indicates that (1) there is no significant loss of neurons from the nbM in HD, and (2) that the previously described cytologic changes in the neurons of this nucleus in HD patients do not differ significantly from controls. These findings are consistent with the working hypothesis that the types of dementia associated with reductions of neocortical CAT activity are characterized by dysfunction or death of neurons in the nbM, but dementing disorders with normal neocortical CAT activity manifest no major abnormalities in this cholinergic nucleus of the basal forebrain. PMID:6225032

  18. Functional morphology of the suprachiasmatic nucleus.

    PubMed

    Ibata, Y; Okamura, H; Tanaka, M; Tamada, Y; Hayashi, S; Iijima, N; Matsuda, T; Munekawa, K; Takamatsu, T; Hisa, Y; Shigeyoshi, Y; Amaya, F

    1999-07-01

    In mammals, the biological clock (circadian oscillator) is situated in the suprachiasmatic nucleus (SCN), a small bilaterally paired structure just above the optic chiasm. Circadian rhythms of sleep-wakefulness and hormone release disappear when the SCN is destroyed, and transplantation of fetal or neonatal SCN into an arrhythmic host restores rhythmicity. There are several kinds of peptide-synthesizing neurons in the SCN, with vasoactive intestinal peptide, arginine vasopressin, and somatostatine neurons being most prominent. Those peptides and their mRNA show diurnal rhythmicity and may or may not be affected by light stimuli. Major neuronal inputs from retinal ganglion cells as well as other inputs such as those from the lateral geniculate nucleus and raphe nucleus are very important for entrainment and shift of circadian rhythms. In this review, we describe morphological and functional interactions between neurons and glial elements and their development. We also consider the expression of immediate-early genes in the SCN after light stimulation during subjective night and their role in the mechanism of signal transduction. The reciprocal interaction between the SCN and melatonin, which is synthesized in the pineal body under the influence of polysynaptic inputs from the SCN, is also considered. Finally, morphological and functional characteristics of clock genes, particularly mPers, which are considered to promote circadian rhythm, are reviewed. PMID:10433864

  19. Low P sub T hadron-nucleus interactions

    NASA Technical Reports Server (NTRS)

    Holynski, R.; Wozniak, K.

    1985-01-01

    The possibility of describing hadron-nucleus (hA) interactions is discussed in terms of a number of independent collisions of the projectile inside the target nucleus. This multiple rescattering may occur on a particle or quark parton level. To investigate the characteristics of hA interactions as a function of antineutrinos advantage is taken of the correlation between the average number antineutrinos of collisions of the projectile inside the nucleus and the number Ng of fast protons ejected from the struck nucleus. The relation antineutrinos vs Ng obtained in antineutrinos was used. For a given target nucleus this allows the selection of interactions occurring at different impact parameters.

  20. a Unified Approach to Hadron-Hadron Hadron-Nucleus and Nucleus-Nucleus Collisions at High Energy

    NASA Astrophysics Data System (ADS)

    Wang, Xin-Nian

    The problem of multiparticle production in high -energy hadron-hadron, hadron-nucleus and nucleus-nucleus collisions are studied systematically in the framework of the Geometrical Branching Model (GBM). The model is based on the geometrical properties of nucleons and the stochastic nature of the interaction among the soft partons. The eikonal formalism is used to relate the elastic and inelastic cross sections and AGK cutting rule is used in connection with the multiparticle production process. The stochastic process of Furry branching is employed to describe the proliferation and hadronization of partons which lead to the produced particles. The approach describes hh, hA and AA collisions in a unified formalism for c.m. energies less than 100 GeV. The result of multiplicity distribution of produced particles exhibits Koba-Nielsen-Olesen (KNO) scaling. The universality of KNO scaling breaks down due to the different geometrical sizes of the hadron and nuclei. For hA and AA collisions, the formalism of GBM allows the hadron to be broken (to h^') by the first collision; indeed, it is the attention given to h^'h and h ^'h^' collisions that distinguishes this work from other earlier investigations on the subject. All of the calculated results are in good agreement with experiments. A general Monte Carlo simulation of GBM for multiparticle production in hh, hA and AA collisions is also given. The particle productivity in particular is studied in detail and is contrasted from the case where quark-gluon plasma (QGP) is produced in the AA collisions. This work forms a definitive description of hadronic and nuclear collisions that can serve as a basis from which exotic features such as the formation of QGP can be recognized as signatures deviating from the normal background.

  1. FeCl3-mediated three-component cascade reaction: an effective approach to the construction of highly functionalized pyrrolo[1,2-c]quinazolinones.

    PubMed

    Zheng, Hu-Fei; Yu, Zhi-Hua; Yuan, Wei; Tang, Zi-Long; Clough, John; Gu, Yu-Cheng; Shi, De-Qing

    2014-02-01

    An unexpected FeCl3-mediated three-component cascade reaction has been used to construct structurally diverse pyrrolo[1,2-c]quinazolinone derivatives with potential biological activities. This method has advantages of mild conditions, simple work-up, as well as wide substrate scope, which makes it a powerful approach to the synthesis of diverse pyrrolo[1,2-c]quinazolinones. This cascade reaction involves 1,3-dipolar cycloaddition between azomethine ylides and allenoates, followed by intramolecular nucleophilic addition in the presence of FeCl3. The obtained products could be easily transformed into derivatives with the pyrrolo[2,3-c]quinazoline alkaloid skeleton. PMID:24382830

  2. Measurement of the exclusive cross section sup 12 C(. nu. sub e , e sup minus ) sup 12 N(g. s. )

    SciTech Connect

    Allen, R.C.; Chen, H.H.; Doe, P.J.; Hausamann, R.; Lee, W.P.; Lu, X.; Mahler, H.J.; Potter, M.E.; Wang, K.C. ); Bowles, T.J.; Burman, R.L.; Carlini, R.D.; Cochran, D.R.F.; Frank, J.S.; Piasetzky, E.; Sandberg, V.D. ); Krakauer, D.A.; Talaga, R.L. )

    1990-04-16

    The neutrino-induced nuclear transition {sup 12}C({nu}{sub {ital e}},{ital e}{sup {minus}}){sup 12}N (g.s.) has been observed with a 15-ton fine-grained tracking detector. The exclusive final state is identified by both an electron track and the positron decay of the {sup 12}N. From the observation of 181{plus minus}17 {sup 12}C({nu}{sub {ital e}},{ital e}{sup {minus}}){sup 12}N (g.s.) events with subsequent positron decays the flux-averaged cross section, equivalent to the cross section for 35.0-MeV neutrinos, is (1.05{plus minus}0.10(stat){plus minus}0.10(syst)){times}10{sup {minus}41} cm{sup 2}. This result is in good agreement with recent calculations.

  3. Formation of a necklike structure in {sup 35}Cl+{sup 12}C and {sup 197}Au reactions at 43 MeV/nucleon

    SciTech Connect

    Larochelle, Y.; Gingras, L.; Beaulieu, L.; Qian, X.; Saddiki, Z.; Djerroud, B.; Dore, D.; Laforest, R.; Roy, R.; Samri, M.; St-Pierre, C.; Ball, G.C.; Bowman, D.R.; Galindo-Uribarri, A.; Hagberg, E.; Horn, D.; Lopez, J.A.; Robinson, T.

    1997-04-01

    The experimental signature of the formation of a necklike structure, with a velocity between that of the projectilelike emitter and that of the targetlike emitter, is investigated with the same beam and experimental setup for targets lighter and heavier than the projectile. The reactions are {sup 35}Cl on {sup 12}C and on {sup 197}Au at 43 MeV/nucleon. Particle velocity distributions are compared with two-source statistical simulations and the presence of a necklike structure is inferred from the data. In the second part of the paper, dynamical model simulations with the formation of a necklike structure are presented for the {sup 35}Cl+{sup 12}C system at 43 MeV/nucleon. {copyright} {ital 1997} {ital The American Physical Society}

  4. Angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Grozdanov, D. N.; Zontikov, A. O.; Kopach, Yu. N.; Rogov, Yu. N.; Ruskov, I. N.; Sadovsky, A. B.; Skoy, V. R.; Barmakov, Yu. N.; Bogolyubov, E. P.; Ryzhkov, V. I.; Yurkov, D. I.

    2016-07-01

    The work is devoted to measuring the angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei. A portable ING-27 neutron generator (designed and fabricated at VNIIA, Moscow) with a built-in 64-pixel silicon α-detector was used as a source of tagged neutrons. The γ-rays of characteristic nuclear radiation from 12C were detected with a spectrometric system that consisted of 22 γ-detectors based on NaI(Tl) crystals arranged around the carbon target. The measured angular distribution of 4.43-MeV γ-rays is analyzed and compared with the results of other published experimental works.

  5. Nuclear radii calculations in various theoretical approaches for nucleus-nucleus interactions

    SciTech Connect

    Merino, C.; Novikov, I. S.; Shabelski, Yu.

    2009-12-15

    The information about sizes and nuclear density distributions in unstable (radioactive) nuclei is usually extracted from the data on interaction of radioactive nuclear beams with a nuclear target. We show that in the case of nucleus-nucleus collisions the values of the parameters depend somewhat strongly on the considered theoretical approach and on the assumption about the parametrization of the nuclear density distribution. The obtained values of root-mean-square radii (R{sub rms}) for stable nuclei with atomic weights A=12-40 vary by approximately 0.1 fm when calculated in the optical approximation, in the rigid target approximation, and using the exact expression of the Glauber theory. We present several examples of R{sub rms} radii calculations using these three theoretical approaches and compare these results with the data obtained from electron-nucleus scattering.

  6. Cold breakup of spectator residues in nucleus-nucleus collisions at high energy

    NASA Astrophysics Data System (ADS)

    Aichelin, J.; Hüfner, J.; Ibarra, R.

    1984-07-01

    Inclusive data from fragmentation reactions of the type AP+AT-->Z+X are analyzed and a reaction mechanism is proposed. A projectile AP (p, He, α, or Ne) collides with a target nucleus AT (Au) and one fragment with charge Z and energy E is observed at a solid angle Ω. Projectile energies vary between 84A MeV and several A GeV. We propose a parametrization for the triple differential cross section d3σdΩ dE dZ with six free parameters. The parametrization generalizes the two-vector model which is often used to describe spallation products in proton-nucleus collisions. By fitting data from various experiments we establish a systematics of the six parameters. The experimental values of the parameters can be quantitatively understood in a model where the target nucleus breaks into several fragments similar to the shattering of glass.

  7. The orientation of nucleus, nucleus-associated body and protruding nucleolus in aggregating Dictyostelium discoideum.

    PubMed

    Sameshima, M

    1985-02-01

    Dictyostelium discoideum growing or developing on cellulose dialysis membranes were fixed with acrolein vapour for electron microscopy. In interphase amoebae, nucleoli began to protrude from the nuclei. The percentage of cells with protruding nucleoli increased during aggregation by a value approximately twice as high in aggregation streams as in centers. Cells in pseudoplasmodia showed only a low percentage and protrusions disappeared at early culmination stage. The protrusions did not reappear when cells from dissociated pseudoplasmodia migrated toward cAMP. Thus the formation of the protrusions did not depend solely on chemotaxis; rather, it was specific to the aggregation stage. In aggregation streams, the nucleus was anterior in the cell, with the protrusion at its anterior periphery. In contrast, the nucleus associated body (NAB) was evident at the cell's mid-point. This orientation of nucleus and NAB in the aggregating slime mould amoeba is contrary to that seen in human neutrophils or cultured mouse 3T3 cells. PMID:2981691

  8. {sup 12}C({alpha},{gamma}){sup 16}O E2 cross section: R-matrix fits combined with a microscopic cluster model

    SciTech Connect

    Dufour, M.

    2008-07-15

    The E2 component of the {sup 12}C({alpha},{gamma}){sup 16}O cross section is investigated in two ways: by a microscopic cluster model, and by R-matrix fits. The {alpha}+{sup 12}C microscopic calculation is performed in the framework of the generator coordinate method (GCM) by including all {sup 12}C states (T=0) within the p shell. Using different nucleon-nucleon interactions we find S{sub E2}(300 keV){approx_equal}50 keV {center_dot} b for ground-state transitions. We also study cascade transitions to the 0{sub 2}{sup +} and 2{sub 1}{sup +} excited states of {sup 16}O. Then the S-factor is analyzed in the phenomenological R-matrix theory. We show that the background term plays a crucial role, and cannot be determined without ambiguity. Using the experimental phase shifts and capture cross sections, only an upper limit on the extrapolated S factor can be obtained [S{sub E2}(300 keV)<190 keV {center_dot} b]. To constrain the R-matrix analysis, we use the GCM asymptotic normalization constant (ANC) of the 2{sub 1}{sup +} level, well known to be a cluster state. This procedure strongly reduces the uncertainties on the R-matrix fit, and we end up with a recommended value of S{sub E2}(300 keV)=42{+-}2 keV {center_dot} b. We show that ANC values derived from indirect methods are not consistent with the {sup 12}C({alpha},{gamma}){sup 16}O cascade transitions to the 2{sub 1}{sup +} state, and suggest that a remeasurement of this cross section is desirable.

  9. Resonance strengths in the {sup 14}N(p,gamma){sup 15}O and {sup 15}N(p,alphagamma){sup 12}C reactions

    SciTech Connect

    Marta, Michele; Trompler, Erik; Bemmerer, Daniel; Beyer, Roland; Grosse, Eckart; Hannaske, Roland; Junghans, Arnd R.; Nair, Chithra; Schwengner, Ronald; Wagner, Andreas; Yakorev, Dmitry; Broggini, Carlo; Caciolli, Antonio; Erhard, Martin; Menegazzo, Roberto; Fueloep, Zsolt; Gyuerky, Gyoergy; Szuecs, Tamas; Vezzu, Simone

    2010-05-15

    The {sup 14}N(p,gamma){sup 15}O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The {sup 15}N(p,alphagamma){sup 12}C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The {sup 14}N(p,gamma){sup 15}O and {sup 15}N(p,alphagamma){sup 12}C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at E{sub p} = 1058 keV in {sup 14}N(p,gamma){sup 15}O and at E{sub p} = 897 and 430 keV in {sup 15}N(p,alphagamma){sup 12}C have been determined with improved precision, relative to the well-known resonance at E{sub p} = 278 keV in {sup 14}N(p,gamma){sup 15}O. The new recommended values are omegagamma=0.353+-0.018, 362+-20, and 21.9+-1.0 eV for their respective strengths. In addition, the branching ratios for the decay of the E{sub p} = 1058 keV resonance in {sup 14}N(p,gamma){sup 15}O have been redetermined. The data reported here should facilitate future studies of off-resonant capture in the {sup 14}N(p,gamma){sup 15}O reaction that are needed for an improved R-matrix extrapolation of the cross section. In addition, the data on the 430 keV resonance in {sup 15}N(p,alphagamma){sup 12}C may be useful for hydrogen depth profiling.

  10. Comparative study of dose distributions and cell survival fractions for 1H, 4He, 12C and 16O beams using Geant4 and Microdosimetric Kinetic model

    NASA Astrophysics Data System (ADS)

    Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Bleicher, Marcus

    2015-04-01

    Depth and radial dose profiles for therapeutic 1H, 4He, 12C and 16O beams are calculated using the Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT). 4He and 16O ions are presented as alternative options to 1H and 12C broadly used for ion-beam cancer therapy. Biological dose profiles and survival fractions of cells are estimated using the modified Microdosimetric Kinetic model. Depth distributions of cell survival of healthy tissues, assuming 10% and 50% survival of tumor cells, are calculated for 6 cm SOBPs at two tumor depths and for different tissues radiosensitivities. It is found that the optimal ion choice depends on (i) depth of the tumor, (ii) dose levels and (iii) the contrast of radiosensitivities of tumor and surrounding healthy tissues. Our results indicate that 12C and 16O ions are more appropriate to spare healthy tissues in the case of a more radioresistant tumor at moderate depths. On the other hand, a sensitive tumor surrounded by more resistant tissues can be better treated with 1H and 4He ions. In general, 4He beam is found to be a good candidate for therapy. It better spares healthy tissues in all considered cases compared to 1H. Besides, the dose conformation is improved for deep-seated tumors compared to 1H, and the damage to surrounding healthy tissues is reduced compared to heavier ions due to the lower impact of nuclear fragmentation. No definite advantages of 16O with respect to 12C ions are found in this study.

  11. Observation of γ-delayed 3 α breakup of the 15.11 and 12.71 MeV states in 12C

    NASA Astrophysics Data System (ADS)

    Kirsebom, O. S.; Alcorta, M.; Borge, M. J. G.; Cubero, M.; Diget, C. A.; Dominguez-Reyes, R.; Fraile, L.; Fulton, B. R.; Fynbo, H. O. U.; Galaviz, D.; Garcia, G.; Hyldegaard, S.; Jeppesen, H. B.; Jonson, B.; Joshi, P.; Madurga, M.; Maira, A.; Muñoz, A.; Nilsson, T.; Nyman, G.; Obradors, D.; Perea, A.; Riisager, K.; Tengblad, O.; Turrion, M.

    2009-09-01

    The reactions 10B (3He , pααα) at 4.9 MeV and 11B (3He , dααα) at 8.5 MeV have been used to investigate the γ decay of states in 12C. By measuring the four-body final state in complete kinematics we are able to detect γ transitions indirectly. We find γ transitions from the 15.11 MeV state in 12C to the 12.71, 11.83, 10.3 and 7.65 MeV states followed by their breakup into three α particles. The relative γ-ray branching ratios obtained are (1.2 ± 0.3), (0.32 ± 0.12), (1.4 ± 0.2) and (4.4 ± 0.8) %, respectively, with the remaining (92.7 ± 1.0) % of the γ decays going to the bound states. We obtain Γα / Γ = (2.8 ± 1.2) % for the isospin-forbidden α decay of the 15.11 MeV state. From the 12.71 MeV state we find γ transitions to the 10.3 and 7.65 MeV states. The relative γ-ray branching ratios are (0.9-0.5+0.6) and (2.6-1.2+1.6) %, respectively, with the remaining (96.6-1.3+1.7) % of the γ decays going to the bound states. Finally, we discuss the relation between the β decay of 12N and 12B to states in 12C and the γ decay of the 15.11 MeV analog in 12C to the same states.

  12. The {beta}-delayed {alpha}-spectrum of {sup 16}N and the astrophysical aspects of the {sup 12}C({alpha},{gamma}){sup 16}O reaction

    SciTech Connect

    Azuma, R.E.; Buchmann, L.; Barker, F.C.

    1995-08-01

    Radiative alpha-capture by {sup 12}C is a key process occurring during the helium-burning phase in red giant stars, and its rate remains one of the most significant uncertainties in the nucleosynthetic calculations for massive stars. This is largely due to the lack of precise experimental information concerning the values of the reduced {alpha}-particle widths of the J{sup {pi}} = 1{sup {minus}} and 2{sup +} subthreshold states in {sup 16}O to which the higher-energy radiative capture data are only weakly sensitive. Of these two states, the reduced {alpha}-width of the E{sub x} = 7.12 MeV J{sup {pi}} = 1{sup {minus}} level has been predicted to have a considerable effect on the structure of the hitherto unmeasured low-energy region of the {beta}-delayed {alpha}-particle spectrum of {sup 16}N. Experiments using the TRIUMF isotope separator TISOL have been performed to measure this {alpha}-spectrum down to an energy of E{sub {alpha}} = 600 keV, utilizing a coincidence technique which also accounts completely for the detector response function. The {alpha}-spectrum, containing 10{sup 6} counts, has been incorporated into both R- and K-matrix analyses along with the previously measured {sup 12}C({alpha},{gamma}){sup 16}O cross section and the {sup 12}C + {alpha} elastic phase shifts to yield a much improved value for S{sub E1}(300) keV. In light of this new determination of S{sub E1}(300), the available radiative capture data and elastic scattering phase shifts are re-analyzed, along with {beta}-delayed {alpha}-spectrum of {sup 16}N in an attempt also to place improved limits on the S{sub E1}(300) contribution to the {sup 12}C({alpha},{gamma}){sup 16}O cross section.

  13. Comparative study of dose distributions and cell survival fractions for 1H, 4He, 12C and 16O beams using Geant4 and Microdosimetric Kinetic model.

    PubMed

    Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Bleicher, Marcus

    2015-04-21

    Depth and radial dose profiles for therapeutic (1)H, (4)He, (12)C and (16)O beams are calculated using the Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT). (4)He and (16)O ions are presented as alternative options to (1)H and (12)C broadly used for ion-beam cancer therapy. Biological dose profiles and survival fractions of cells are estimated using the modified Microdosimetric Kinetic model. Depth distributions of cell survival of healthy tissues, assuming 10% and 50% survival of tumor cells, are calculated for 6 cm SOBPs at two tumor depths and for different tissues radiosensitivities. It is found that the optimal ion choice depends on (i) depth of the tumor, (ii) dose levels and (iii) the contrast of radiosensitivities of tumor and surrounding healthy tissues. Our results indicate that (12)C and (16)O ions are more appropriate to spare healthy tissues in the case of a more radioresistant tumor at moderate depths. On the other hand, a sensitive tumor surrounded by more resistant tissues can be better treated with (1)H and (4)He ions. In general, (4)He beam is found to be a good candidate for therapy. It better spares healthy tissues in all considered cases compared to (1)H. Besides, the dose conformation is improved for deep-seated tumors compared to (1)H, and the damage to surrounding healthy tissues is reduced compared to heavier ions due to the lower impact of nuclear fragmentation. No definite advantages of (16)O with respect to (12)C ions are found in this study. PMID:25825827

  14. Bisannelation with a benzo(1,2-c:4,5-c-prime) difuran equivalent - A new route to linear acene derivatives

    NASA Technical Reports Server (NTRS)

    Luo, Jihmei; Hart, Harold

    1988-01-01

    It was observed that the base peak in the mass spectra of all the Diels-Alder bis adducts of anthracene diendoxide as well as of its tetrahydro derivative appear at m/e 158, corresponding to the radical cation of benzo(1,2-c:4,5-c-prime) difuran (BDF). This paper describes a synthetic equivalent of BDF and demonstrates its utility for obtaining linear acene derivatives.

  15. Nonequilibrium neutron emission from /sup 12/C + /sup 158/Gd and /sup 13/C + /sup 157/Gd reactions. [103 to 160 MeV

    SciTech Connect

    Plasil, F.; Beene, J.R.; Ferguson, R.L.

    1981-01-01

    The energy dependence of nonequilibrium neutron emission (NNE) and the effects of projectile structure were investigated in these reactions between 103 and 160 MeV. Neutron energy spectra and angular distributions were measured. Typical spectra show no projectile structure effect. The absence of difference in NNE between /sup 12/C- and /sup 13/C-induced reactions was also noted. The Wilczynski model agrees well with the data. 5 figures, 1 table. (RWR)

  16. THE GALACTIC R CORONAE BOREALIS STARS: THE C{sub 2} SWAN BANDS, THE CARBON PROBLEM, AND THE {sup 12}C/{sup 13}C RATIO

    SciTech Connect

    Hema, B. P.; Pandey, Gajendra; Lambert, David L. E-mail: pandey@iiap.res.in

    2012-03-10

    Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C{sub 2} Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C{sub 2} bands are used to derive the {sup 12}C abundance, and the (1, 0) {sup 12}C{sup 13}C band to determine the {sup 12}C/{sup 13}C ratios. The carbon abundance derived from the C{sub 2} Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He = 0.1%) to 10.5 (C/He = 10%). Carbon abundances derived from C I lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the 'carbon problem'. In principle, the carbon abundances obtained from C{sub 2} Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C{sub 2} bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C{sub 2} carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the {sup 12}C/{sup 13}C ratios are discussed in light of the double degenerate and the final flash scenarios.

  17. Benzo[1,2-c;4,5-c‧]Bis[1,2,5]Thiadiazole in Organic Optoelectronics: A Mini-Review

    NASA Astrophysics Data System (ADS)

    Tam, Teck Lip Dexter; Wu, Jishan

    2015-09-01

    In this paper, organic optoelectronic research activities in the field of benzo[1,2-c;4,5-c‧]bis[1,2,5]thiadiazole (BBT)-based materials are reviewed. Synthetic pathways to the BBT core and its computational studies are described. Collective observations from separate reports suggest open-shell biradical nature of BBT-based materials. Future research directions for these materials are also described.

  18. Complete and incomplete fusion in the {sup 32}S+{sup 12}C reaction at E({sup 32}S)=20 MeV/A

    SciTech Connect

    Aiello, S.; Pirrone, S.; Politi, G.; Arena, N.; Cavallaro, Seb.; Sambataro, S.; Geraci, E.; Porto, F.; Lanzalone, G.

    1999-11-16

    Velocity distribution of mass identified evaporation residues produced in the {sup 32}S+{sup 12}C reaction at E({sup 32}S)=20 MeV/A have been measured using time-of-flight techniques. These distributions were used to separate the complete and incomplete fusion components. The complete fusion cross section and the deduced critical angular momenta are compared with other experimental data and the predictions of existing models.

  19. Complete and Incomplete fusion in the {sup 32}S+{sup 12}C reaction at E({sup 32}S)=20 MeV/A

    SciTech Connect

    S. Aiello; N. Arena; S. Cavallaro; E. Geraci; G. Lanzalone; S. Pirrone; G. Politi; F. Porto; S. Sambataro

    1999-12-31

    Velocity distribution of mass identified evaporation residues produced in the {sup 32}S+{sup 12}C reaction at E({sup 32}S)=20 MeV/A have been measured using time-of-flight techniques. These distributions were used to separate the complete and incomplete fusion components. The complete fusion cross section and the deduced critical angular momenta are compared with other experimental data and the predictions of existing models.

  20. Millimeter-Wave Observations of Circumstellar 14N/15N and 12C/13C Ratios: New Insights into J-Type Stars

    NASA Astrophysics Data System (ADS)

    Adande, Gilles; Ziurys, Lucy M.; Woolf, Neville

    2016-06-01

    Measurements of 14N/15N and 12C/13C isotopic ratios have been conducted towards circumstellar envelopes of a sample of evolved stars using the J = 3→2 rotational transitions of the isotopologues of HCN, observed with the Submillimeter Telescope (SMT) of the Arizona Radio Observatory (ARO). Towards the J-type stars Y CVn and RY Dra, where 12C/13C ~ 3, the 14N/15N ratios were found to be 120-180 and 225, respectively. The 14N/15N ratio is thus anomalously low relative to interstellar values and a factor ~100 lower than equilibrium values predicted from the CNO cycle. Combining these results with previous chemical and isotopic prior observations of these stars, we conclude that two anomalous behaviors are likely to have occurred in Y CVn and RY Dra. First, the stellar envelope failed to participate in the normal mixing seen in low mass red giants, in which C and then O are substantially converted to N. Secondly, both the carbon enrichment and anomalous isotopic composition of both 13C and15N could have been caused by a plume of hot gas, hydrogen poor but enriched in 12C, from a helium flash mixing into the envelope.

  1. The carbon abundance and 12C/13C isotopic ratio in the atmosphere of Arcturus from 2.3 µm CO bands

    NASA Astrophysics Data System (ADS)

    Pavlenko, Ya. V.

    2008-09-01

    We have modeled absorption lines of the 12CO and 13CO (Δ υ = 2) molecular bands at λλ 2.29 2.45 µm in the spectrum of Arcturus (K2III). A grid of model atmospheres and synthetic spectra were computed for the red giant using T eff = 4300, log g = 1.5, and the elemental abundances of Peterson et al. (1993), with the exception of the abundances of carbon, log N(C), and oxygen, log N(O) and the carbon isotopic ratio, 12C/13C, which were varied in our computations. The computed spectra were compared to the observed spectrum of Arcturus from the atlas of Hinkle et al. (1976). The best fit between the synthetic and observed spectra is achieved for log N(C) = -3.78, 12C/13C = 8 ± 0.5. We discuss the dependence of 12C/13C on log N(C) and log N(O) in the atmosphere of the red giant.

  2. Tricyclic Pyrazoles. Part 5. Novel 1,4-Dihydroindeno[1,2-c]pyrazole CB2 Ligands Using Molecular Hybridization Based on Scaffold Hopping

    PubMed Central

    Murineddu, Gabriele; Asproni, Battistina; Ruiu, Stefania; Deligia, Francesco; Falzoi, Matteo; Pau, Amedeo; Thomas, Brian F; Zhang, Yanan; Pinna, Gérard A; Pani, Luca; Lazzari, Paolo

    2012-01-01

    In search of new selective CB2 ligands, the synthesis and preliminary biological evaluation of novel 1,4-dihydroindeno[1,2-c]pyrazole hybrids of the highly potent prototypicals 5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-N-fenchyl-1H-pyrazole-3-carboxamide 1 and 1-(2,4-dichlorophenyl)-6-methyl-N-(piperidin-1-yl)-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxamide 2 are detailed. We postulated that the introduction of those pharmacophoric elements essential for activity of 1 in the tricyclic core of 2 might provide CB2 ligands with further improved receptor selectivity and biological activity. Among the compounds, 6-chloro-7-methyl-1-(2,4-dichlorophenyl)-N-fenchyl-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxamide (22) exhibited low two digit nanomolar affinity for the cannabinoid CB2R and maintained a high level of CB2-selectivity. PMID:22876271

  3. Vitamin B12[c-lactone], a biologically inactive corrinoid compound, occurs in cultured and dried lion's mane mushroom (Hericium erinaceus) fruiting bodies.

    PubMed

    Teng, Fei; Bito, Tomohiro; Takenaka, Shigeo; Yabuta, Yukinori; Watanabe, Fumio

    2014-02-19

    This study determined the vitamin B12 content of the edible medicinal mushroom Hericium erinaceus, lion's mane mushroom fruiting body, using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Trace levels (0.04-0.36 μg/100 g dry weight) of vitamin B12 were found in most of the dried mushroom samples, and two samples contained slightly higher levels (0.56 and 1.04 μg/100 g dry weight, respectively) of vitamin B12. We purified the corrinoid compounds from the extracts of dried lion's mane mushroom fruiting bodies using an immunoaffinity column and identified them as vitamin B12 or vitamin B12[c-lactone] (or both) based on LC/ESI-MS/MS chromatograms. This is the first report on an unnatural corrinoid, vitamin B12[c-lactone], occurring in foods. Vitamin B12[c-lactone] was simple to produce during incubation of authentic vitamin B12 and chloramine-T, an antimicrobial agent, at varying pH values (3.0-7.0) and was completely inactive in the vitamin B12-dependent bacteria that are generally used in vitamin B12 bioassays. PMID:24506286

  4. {gamma}-ray production by proton and {alpha}-particle induced reactions on {sup 12}C, {sup 16}O, {sup 24}Mg, and Fe

    SciTech Connect

    Belhout, A.; Kiener, J.; Coc, A.; Duprat, J.; Engrand, C.; Fitoussi, C.; Gounelle, M.; Lefebvre-Schuhl, A.; Sereville, N. de; Tatischeff, V.; Thibaud, J.-P.; Chabot, M.; Hammache, F.; Benhabiles-Mezhoud, H.

    2007-09-15

    {gamma}-ray production cross sections for proton and {alpha}-particle interactions with {sup 12}C, {sup 16}O, {sup 24}Mg, and Fe have been measured in the energy range 5-25 MeV with proton beams and 5-40 MeV with {alpha}-particle beams. Isotopically pure foils of {sup 24}Mg and foils of natural isotopical composition of C, MgO, and Fe have been used. {gamma}-ray angular distributions were obtained with five high-purity Ge detectors with bismuth germanate Compton shields placed at angles of 45 deg. to 157.5 deg. Cross sections for more than 50 different {gamma}-ray transitions were extracted, and for many of them no data have been published before. Comparison of present data with data available in the literature shows mostly good to excellent agreement. In addition to the production cross sections, high-statistics, low-background line shapes of the 4.438 MeV {sup 12}C {gamma} ray from inelastic scattering off {sup 12}C and spallation of {sup 16}O were obtained. Comparison with nuclear reaction calculations shows that these data place interesting constraints on nuclear reaction models.

  5. Design, Synthesis, and Biological Evaluation of 1-Methyl-1,4-dihydroindeno[1,2-c]pyrazole Analogues as Potential Anticancer Agents Targeting Tubulin Colchicine Binding Site.

    PubMed

    Liu, Yan-Na; Wang, Jing-Jing; Ji, Ya-Ting; Zhao, Guo-Dong; Tang, Long-Qian; Zhang, Cheng-Mei; Guo, Xiu-Li; Liu, Zhao-Peng

    2016-06-01

    By targeting a new binding region at the interface between αβ-tubulin heterodimers at the colchicine binding site, we designed a series of 7-substituted 1-methyl-1,4-dihydroindeno[1,2-c]pyrazoles as potential tubulin polymerization inhibitors. Among the compounds synthesized, 2-(6-ethoxy-3-(3-ethoxyphenylamino)-1-methyl-1,4-dihydroindeno[1,2-c]pyrazol-7-yloxy)acetamide 6a and 2-(6-ethoxy-3-(3-ethoxyphenylamino)-1-methyl-1,4-dihydroindeno[1,2-c]pyrazol-7-yloxy)-N-hydroxyacetamide 6n showed noteworthy low nanomolar potency against HepG2, Hela, PC3, and MCF-7 cancer cell lines. In mechanism studies, 6a inhibited tubulin polymerization and disorganized microtubule in A549 cells by binding to tubulin colchicine binding site. 6a arrested A549 cells in G2/M phase that was related to the alterations in the expression of cyclin B1 and p-cdc2. 6a induced A549 cells apoptosis through the activation of caspase-3 and PARP. In addition, 6a inhibited capillary tube formation in a concentration-dependent manner. In nonsmall cell lung cancer xenografts mouse model, 6a suppressed tumor growth by 59.1% at a dose of 50 mg/kg (ip) without obvious toxicity, indicating its in vivo potential as anticancer agent. PMID:27172319

  6. Electromagnetic processes in nucleus-nucleus collisions relating to space radiation research

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Most of the papers within this report deal with electromagnetic processes in nucleus-nucleus collisions which are of concern in the space radiation program. In particular, the removal of one and two nucleons via both electromagnetic and strong interaction processes has been extensively investigated. The theory of relativistic Coulomb fission has also been developed. Several papers on quark models also appear. Finally, note that the theoretical methods developed in this work have been directly applied to the task of radiation protection of astronauts. This has been done by parameterizing the theoretical formalism in such a fashion that it can be used in cosmic ray transport codes.

  7. The effect of the relative nuclear size on the nucleus-nucleus interactions

    NASA Technical Reports Server (NTRS)

    Erofeeva, I. N.; Murzin, V. S.; Sivoklokov, S. Y.; Smirnova, L. N.

    1985-01-01

    The experimental data on the interactions of light nuclei (d, He(4), C(12)) at the momentum 4.2 GeV/cA with the carbon nuclei were taken in the 2-m propane bubble chamber. The distributions in the number of interacting nucleons, the spectra of protons, the mean energies of secondary pions and protons, the mean fractions of energy transferred to the pion and nucleon components are presented. The results of the investigation of the mechanism of nucleus-nucleus interactions can be used to calculate the nuclear cascades in the atmosphere.

  8. Pion and Kaon Lab Frame Differential Cross Sections for Intermediate Energy Nucleus-Nucleus Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Blattnig, Steve R.

    2008-01-01

    Space radiation transport codes require accurate models for hadron production in intermediate energy nucleus-nucleus collisions. Codes require cross sections to be written in terms of lab frame variables and it is important to be able to verify models against experimental data in the lab frame. Several models are compared to lab frame data. It is found that models based on algebraic parameterizations are unable to describe intermediate energy differential cross section data. However, simple thermal model parameterizations, when appropriately transformed from the center of momentum to the lab frame, are able to account for the data.

  9. Observation of direct hadronic pairs in nucleus-nucleus collisions in JACEE emulsion chambers

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Jurak, A.; Hayashi, T.; Iwai, J.; Jones, W. V.

    1985-01-01

    In a number of high energy ( or = 1 TeV/amu) nucleus-nucleus collisions observed in Japanese-American Cooperative Emulsion Experiment (JACEE) emulsion chambers, nonrandom spatial association of produced charged particles, mostly hadronic pairs, are observed. Similar narrow pairs are observed in about 100 events at much low energy (20 to 60 GeV/amu). Analysis shows that 30 to 50% of Pair abundances are understood by the Hambury-Brown-Twiss effect, and the remainder seems to require other explanations.

  10. High energy factorization in nucleus-nucleus collisions. II. Multigluon correlations

    SciTech Connect

    Gelis, Francois; Lappi, Tuomas

    2008-09-01

    We extend previous results from the preceding paper on factorization in high energy nucleus-nucleus collisions by computing the inclusive multigluon spectrum to next-to-leading order. The factorization formula is strictly valid for multigluon emission in a slice of rapidity of width {delta}Y{<=}{alpha}{sub s}{sup -1}. Our results shows that often neglected disconnected graphs dominate the inclusive multigluon spectrum, and are crucial in order to achieve factorization for this quantity. These results provide a dynamical framework for the Glasma flux tube picture of the striking ''ridge''-like correlation seen in heavy ion collisions.

  11. Two-particle correlations of pions and light nuclear fragments in nucleus-nucleus interactions at an energy of 3.6 GeV/nucleon

    SciTech Connect

    Ad`yasevich, B.P.; Antonenko, V.G.; Vasil`ev, M.A.; Vinogradov, A.A.; Ippolitov, M.S.; Karadzhev, K.V.; Lebedev, A.L.; Man`ko, V.I.; Mgebrishvili, G.M.; Nikolaev, S.A.

    1994-11-01

    ACorrelations between a charged particle emitted in the angular interval 10-32{degrees} (in the lab system) and a pion emitted in the angular interval 45-135{degrees} are measured for the interactions of {sup 12}C and {sup 4}He nuclei of energy 3.6 GeV/nucleon with various nuclear targets. In all cases, the correlated emission of such particles is discovered. As in the case of baryonic nuclear fragments, correlations are negative for light targets (a fragment and the first particle are emitted preferentially in opposite directions). However, in contrast to the case of baryonic fragments, the amplitudes of the correlations decrease with increasing mass of the target nucleus, and correlations even become positive in the case of a Pb target. The magnitudes of the correlations depend systematically on the characteristics of the entrance and exit channels. As in the case of baryonic nuclear fragments, these observations are consistent with the notion of collective motion in nuclear matter. In addition, the effect of pion rescattering with reflection in nuclear matter is observed. 6 refs., 3 figs.

  12. The Checkerboard Model of the Nucleus

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2014-03-01

    The Lach Checker Board Model (CBM) of the nucleus and the associated ESM predicts that nature has 5 generations of quarks not 3. The heaviest generation in the Extended Standard Model (ESM) has a t' quark of mass 65 GeV and a b' quark of 42.4 GeV. The lepton in this generation has a mass of 27 GeV. Part of this theory evolved because it appears that the quarks and lepton of each generation have masses related by the geometric mean. The Geometric mean of 65 and 27 is 42. Charge is conserved (+2/3 and -1 is -1/3). Details of how this theory evolved is found on my web site (http://checkerboard.dnsalias.net) or in the following references [T.M. Lach, Checkerboard Structure of the Nucleus, Infinite Energy, Vol. 5, issue 30, (2000); T.M. Lach, Masses of the Sub-Nuclear Particles, nucl-th/0008026, @http://xxx.lanl.gov/] One independent check of this CB model is that the wavelength of the ``up'' quark orbiting inside the proton at 84.8123% the speed of light around the ``dn'' quark in the center turns out to be exactly one DeBroglie wavelength. This explains the mass of the proton and neutron and their magnetic moments. This along with the beautiful symmetric 2D structure of the He nucleus led to the evolution of this theory. One would expect a t'-anti t' meson of mass of about 130 GeV.

  13. Angular distributions of neutron-nucleus collisions

    SciTech Connect

    Mukhopadhyay, Tapan; Lahiri, Joydev; Basu, D. N.

    2011-06-15

    We derive the total and the differential cross sections with respect to angle for neutron-induced reactions from an analytical model having a simple functional form to demonstrate the quantitative agreement with the measured cross sections. The energy dependence of the neutron-nucleus interaction cross sections are estimated successfully for energies ranging from 5 to 600 MeV. In this work, the effect of the imaginary part of the nuclear potential is treated more appropriately compared to our earlier work. The angular distributions for neutron scattering also agree reasonably well with the experimental data at forward angles.

  14. Unveiling the nucleus of NGC 7172

    NASA Astrophysics Data System (ADS)

    Smajić, S.; Fischer, S.; Zuther, J.; Eckart, A.

    2012-08-01

    Aims: We present the results of near-infrared (NIR) H + K European Southern Observatory SINFONI integral field spectroscopy (IFS) of the Seyfert 2 galaxy NGC 7172. We investigate the central 800 pc, concentrating on excitation conditions, morphology, and stellar content. NGC 7172 was selected from a sample of the ten nearest Seyfert 2 galaxies from the Veron-Cetty & Veron catalogue. All objects were chosen as test cases for adaptive optics (AO) assisted observations that allow a detailed study (at high spatial and spectral resolution) of the nuclear and host environments. NGC 7172 has a prominent dustlane crossing the central galaxy region from east to west, which makes it an ideal candidate to investigate the effect of obscuration by strong galactic extinction on (active) galaxies and their classification. Methods: The NIR is less influenced by dust extinction than optical light and is sensitive to the mass-dominating stellar populations. SINFONI integral field spectroscopy combines NIR imaging and spectroscopy and provides us with the opportunity to analyze several emission and absorption lines to investigate the stellar populations and ionization mechanisms over the 4″ × 4″ field of view (FOV). Results: We present emission and absorption line measurements in the central 800 pc of NGC 7172. The detection of [Si vi] and broad Paα and Brγ components are clear signs of an accreting super-massive black hole hiding behind the prominent dustlane at visible wavelengths. Hot temperatures of about 1300 K are indicative of a dusty torus in the nuclear region. Narrow components of Paα and Brγ enable us to make an extinction measurement. Our measures of the molecular hydrogen lines, hydrogen recombination lines, and [Fe ii] indicate that the excitation of these lines is caused by an active galactic nucleus. The central region of the galactic disk is predominantly inhabited by gas, dust, and an old K-M type giant stellar population. The gaseous, molecular, and

  15. Parity violation in the compound nucleus

    SciTech Connect

    Mitchell, G.E.; Crawford, B.E.; Grossmann, C.A.; Lowie, L.Y.; Bowman, J.D.; Knudson, J.; Penttilae, S.; Seestrom, S.J.; Smith, D.A.; Yen, Y.; Yuan, V.W.; Delheij, P.P.; Haseyama, T.; Masaike, A.; Matsuda, Y.; Postma, H.; Roberson, N.R.; Sharapov, E.I.; Stephenson, S.L.

    1999-06-01

    Measurements have been performed on the helicity dependence of the neutron resonance cross section for many nuclei by our TRIPLE Collaboration. A large number of parity violations are observed. Generic enhancements amplify the signal for symmetry breaking and the stochastic properties of the compound nucleus permit the strength of the symmetry-breaking interaction to be determined without knowledge of the wave functions of individual states. A total of 15 nuclei have been analyzed with this statistical approach. The results are summarized. {copyright} {ital 1999 American Institute of Physics.}

  16. The bare nucleus of comet Neujmin 1

    NASA Technical Reports Server (NTRS)

    Campins, Humberto; A'Hearn, Michael F.; Mcfadden, Lucy-Ann

    1987-01-01

    Simultaneous visible and infrared observations of comet P/Neujmin 1 1984c are presented which show that the comet has a large (mean radius 10 km), dark (geometric albedo 2-3 percent) nucleus with a surface which is mostly inert material but which still shows a low level of gaseous activity. This is the first physical evidence that cometary nuclei can leave behind an inert body after the coma activity ceases. No asteroid or asteroid class has been found to match the reflectance and albedo of this comet except possibly some D asteroids.

  17. The Subthalamic Nucleus, oscillations and conflict

    PubMed Central

    Zavala, Baltazar; Zaghloul, Kareem; Brown, Peter

    2014-01-01

    The subthalamic nucleus (STN), which is currently the most common target for deep brain stimulation for Parkinson’s disease, has received increased attention over the past few years for the roles it may play in functions beyond simple motor control. In this article we will highlight several of the theoretical, interventional, and electrophysiological studies that have implicated the STN in response inhibition. Most influential amongst this evidence has been the reported effect of STN deep brain stimulation in increasing impulsive responses in the laboratory setting. Yet, how this relates to pathological impulsivity in patient’s everyday lives remains uncertain. PMID:25688872

  18. Line parameters including temperature dependences of self- and air-broadened line shapes of 12C16O2: 1.6-μm region

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Miller, Charles E.; Drouin, Brian J.; Payne, Vivienne H.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Gamache, Robert R.

    2016-07-01

    Pressure-broadened line shapes in the 30013←00001 (ν1+4 ν20 +ν3) band of 12C16O2 at 6228 cm-1 are reanalyzed using new spectra recorded with sample temperatures down to 170 K. High resolution, high signal-to-noise (S/N) laboratory measurements of line shapes (Lorentz air- and self-broadened half-width coefficients, pressure-shift coefficients and off-diagonal relaxation matrix element coefficients) as a function of gas sample temperatures for various pressures and volume mixing ratios are presented. The spectra were recorded using two different Fourier transform spectrometers (FTS): (1) the McMath-Pierce FTS located at the National Solar Observatory on Kitt Peak, Arizona (and reported in Devi et al., J Mol Spectrosc 2007;245:52-80) and, (2) the Bruker IFS-125HR FTS at the Jet Propulsion Laboratory in Pasadena, California. The 19 spectra taken at Kitt Peak were all recorded near room temperature while the 27 Bruker spectra were acquired both at room temperature and colder temperatures (170-296 K). Various spectral resolutions (0.004-0.011 cm-1), absorption path lengths (2.46-121 m) and CO2 samples (natural and 12C-enriched) were included in the dataset. To maximize the accuracies of the various retrieved line parameters, a multispectrum nonlinear least squares spectrum fitting software program was used to adjust the ro-vibrational constants (G,B,D etc.) and intensity parameters (including Herman-Wallis terms) instead of directly measuring the individual line positions and intensities. To minimize systematic residuals, line mixing (via off-diagonal relaxation matrix elements) and quadratic speed dependence parameters were included in the analysis. Contributions from other weakly absorbing bands: the 30013←00001 and 30012←00001 bands of 13C16O2, the 30013←00001 band of 12C16O18O, hot bands 31113←01101 and 32212←02201 of 12C16O2, as well as the 40013←10001 and the 40014←10002 bands of 12C16O2, present within the fitted interval were also measured

  19. A thalamic input to the nucleus accumbens mediates opiate dependence.

    PubMed

    Zhu, Yingjie; Wienecke, Carl F R; Nachtrab, Gregory; Chen, Xiaoke

    2016-02-11

    Chronic opiate use induces opiate dependence, which is characterized by extremely unpleasant physical and emotional feelings after drug use is terminated. Both the rewarding effects of a drug and the desire to avoid withdrawal symptoms motivate continued drug use, and the nucleus accumbens is important for orchestrating both processes. While multiple inputs to the nucleus accumbens regulate reward, little is known about the nucleus accumbens circuitry underlying withdrawal. Here we identify the paraventricular nucleus of the thalamus as a prominent input to the nucleus accumbens mediating the expression of opiate-withdrawal-induced physical signs and aversive memory. Activity in the paraventricular nucleus of the thalamus to nucleus accumbens pathway is necessary and sufficient to mediate behavioural aversion. Selectively silencing this pathway abolishes aversive symptoms in two different mouse models of opiate withdrawal. Chronic morphine exposure selectively potentiates excitatory transmission between the paraventricular nucleus of the thalamus and D2-receptor-expressing medium spiny neurons via synaptic insertion of GluA2-lacking AMPA receptors. Notably, in vivo optogenetic depotentiation restores normal transmission at these synapses and robustly suppresses morphine withdrawal symptoms. This links morphine-evoked pathway- and cell-type-specific plasticity in the paraventricular nucleus of the thalamus to nucleus accumbens circuit to opiate dependence, and suggests that reprogramming this circuit holds promise for treating opiate addiction. PMID:26840481

  20. Paraventricular hypothalamic nucleus: axonal projections to the brainstem

    PubMed Central

    Geerling, Joel C.; Shin, Jung-Won; Chimenti, Peter C.; Loewy, Arthur D.

    2010-01-01

    The paraventricular hypothalamic nucleus (PVH) contains many neurons that innervate the brainstem, but information regarding their target sites remains incomplete. Here, we labeled neurons in the rat PVH with an anterograde axonal tracer, Phaseolus vulgaris leucoagglutinin (PHAL) and studied their descending projections in reference to specific neuronal subpopulations throughout the brainstem. While many of their target sites were identified previously, numerous new observations were made. Major findings include: (1) In the midbrain, the PVH projects lightly to the ventral tegmental area, Edinger-Westphal nucleus, ventrolateral periaqueductal gray matter, reticular formation, pedunculopontine tegmental nucleus, and dorsal raphe nucleus. (2) In the dorsal pons, the PVH projects heavily to the pre-locus coeruleus, yet very little to the catecholamine neurons in the locus coeruleus, and selectively targets the viscerosensory subregions of the parabrachial nucleus; (3) In the ventral medulla, the superior salivatory nucleus, retrotrapezoid nucleus, compact and external formations of the nucleus ambiguus, A1 and caudal C1 catecholamine neurons, and caudal pressor area receive dense axonal projections, generally exceeding the PVH projection to the rostral C1 region; (4) The medial nucleus of the solitary tract (including A2 noradrenergic and aldosterone-sensitive neurons) receives the most extensive projections of the PVH, substantially more than the dorsal vagal nucleus or area postrema. Our findings suggest that the PVH may modulate a range of homeostatic functions, including cerebral and ocular blood flow, corneal and nasal hydration, ingestive behavior, sodium intake, and glucose metabolism, as well as cardiovascular, gastrointestinal, and respiratory activities. PMID:20187136

  1. On M31's Double Nucleus

    NASA Technical Reports Server (NTRS)

    Miller, R. H.; Smith, B. F.; Cuzzi, Jeffrey (Technical Monitor)

    1995-01-01

    The recent HST discovery of a double nucleus in M31 brings into prominence the question how long, a second core can survive within the nuclear regions of a galaxy. Physical conditions in the nuclear regions of a typical galaxy help a second core survive, so it can orbit for a long time. possibly for thousands of orbits. Given the nearly uniform mass density in a core, tidal forces within a core radius are compressive in all directions and help the core survive the buffeting it takes as it orbits near the center of the galaxy. We use numerical experiments to illustrate these physical principles. Our method allows the full power of the experiments to be concentrated on the nuclear regions. Spatial resolution of about 0.2 pc comfortably resolves detail within the 1.4 parsec core radius of the second, but brighter core (P1) in M31. We use these physical principles to discuss M31's double nucleus, but they apply to other galaxies as well. and in other astronomical situations such as dumbbell galaxies. galaxies orbiting near the center of a galaxy cluster, and subclustering in galaxy clusters. The experiments also illustrate that galaxy encounters and merging are quite sensitive to external tidal forces, such as those produced by the gravitational potential in a group or cluster of galaxies.

  2. Comet Borrelly Nucleus Found to the Side

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Deep Space 1 flew by comet Borrelly on September 22, 2001 and took these measurements with its plasma instruments between 90,000 kilometers (56,000 miles) and 2,000 kilometers (1,200 miles) away. These data show that the flow of ions around the comet's rocky, icy nucleus (the center of the deep V-shaped feature) is not centered on the comet's nucleus as scientists expected before the Borrelly flyby. Ions in the turbulent flow are heated to about 1 million Kelvin (2 million degrees Fahrenheit) causing the bands of ions to appear broad and jagged compared to the solar wind.

    Deep Space 1 completed its primary mission testing ion propulsion and 11 other advanced, high-risk technologies in September 1999. NASA extended the mission, taking advantage of the ion propulsion and other systems to undertake this chancy but exciting, and ultimately successful, encounter with the comet. More information can be found on the Deep Space 1 home page at http://nmp.jpl.nasa.gov/ds1/ .

    Deep Space 1 was launched in October 1998 as part of NASA's New Millennium Program, which is managed by JPL for NASA's Office of Space Science, Washington, D.C. The California Institute of Technology manages JPL for NASA.

  3. Comet nucleus and asteroid sample return missions

    NASA Astrophysics Data System (ADS)

    Melton, Robert G.; Thompson, Roger C.; Starchville, Thomas F., Jr.; Adams, C.; Aldo, A.; Dobson, K.; Flotta, C.; Gagliardino, J.; Lear, M.; McMillan, C.

    During the 1991-92 academic year, the Pennsylvania State University has developed three sample return missions: one to the nucleus of comet Wild 2, one to the asteroid Eros, and one to three asteroids located in the Main Belt. The primary objective of the comet nucleus sample return mission is to rendezvous with a short period comet and acquire a 10 kg sample for return to Earth. Upon rendezvous with the comet, a tethered coring and sampler drill will contact the surface and extract a two-meter core sample from the target site. Before the spacecraft returns to Earth, a monitoring penetrator containing scientific instruments will be deployed for gathering long-term data about the comet. A single asteroid sample return mission to the asteroid 433 Eros (chosen for proximity and launch opportunities) will extract a sample from the asteroid surface for return to Earth. To limit overall mission cost, most of the mission design uses current technologies, except the sampler drill design. The multiple asteroid sample return mission could best be characterized through its use of future technology including an optical communications system, a nuclear power reactor, and a low-thrust propulsion system. A low-thrust trajectory optimization code (QuickTop 2) obtained from the NASA LeRC helped in planning the size of major subsystem components, as well as the trajectory between targets.

  4. Comet nucleus and asteroid sample return missions

    NASA Technical Reports Server (NTRS)

    Melton, Robert G.; Thompson, Roger C.; Starchville, Thomas F., Jr.; Adams, C.; Aldo, A.; Dobson, K.; Flotta, C.; Gagliardino, J.; Lear, M.; Mcmillan, C.

    1992-01-01

    During the 1991-92 academic year, the Pennsylvania State University has developed three sample return missions: one to the nucleus of comet Wild 2, one to the asteroid Eros, and one to three asteroids located in the Main Belt. The primary objective of the comet nucleus sample return mission is to rendezvous with a short period comet and acquire a 10 kg sample for return to Earth. Upon rendezvous with the comet, a tethered coring and sampler drill will contact the surface and extract a two-meter core sample from the target site. Before the spacecraft returns to Earth, a monitoring penetrator containing scientific instruments will be deployed for gathering long-term data about the comet. A single asteroid sample return mission to the asteroid 433 Eros (chosen for proximity and launch opportunities) will extract a sample from the asteroid surface for return to Earth. To limit overall mission cost, most of the mission design uses current technologies, except the sampler drill design. The multiple asteroid sample return mission could best be characterized through its use of future technology including an optical communications system, a nuclear power reactor, and a low-thrust propulsion system. A low-thrust trajectory optimization code (QuickTop 2) obtained from the NASA LeRC helped in planning the size of major subsystem components, as well as the trajectory between targets.

  5. Neutronic Cross Section Calculations on Fluorine Nucleus

    NASA Astrophysics Data System (ADS)

    Kara, A.; Tel, E.

    2013-06-01

    Certain light nuclei such as Lithium (Li), Beryllium (Be), Fluorine (F) (which are known as FLİBE) and its molten salt compounds (LiF, BeF2 and NaF) can serve as a coolant which can be used at high temperatures without reaching a high vapor pressure. These molten salt compounds are also a good neutron moderator. In this study, cross sections of neutron induced reactions have been calculated for fluorine target nucleus. The new calculations on the excitation functions of 19F( n, 2n), 19F( n, p), 19F( n, xn), 19F( n, xp) have been made. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the full exciton model and the cascade exciton model. The equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, the ( n, 2n) and ( n, p) reaction cross sections have calculated by using evaluated empirical formulas developed by Tel et al. at 14-15 MeV energy. The multiple pre-equilibrium mean free path constant from internal transition have been investigated for 19F nucleus. The obtained results have been discussed and compared with the available experimental data.

  6. Asymmetrical fission and statistical emission of complex fragments from the highly excited {sup 47}V compound nucleus

    SciTech Connect

    Beck, C.; Djerroud, B.; Haas, F.; Freeman, R.M.; Hachem, A.; Heusch, B.; Morsad, A.; Vuillet-A-Crilles, M.; Youlal, M.; Abe, Y.; Dayras, R.; Wieleczko, J.P.; Legrain, R.; Pollaco, E.; Ray, A.; Shapira, D.; Campo, J.G.D.; Kim, H.J.; Cavallaro, S.; De Fillippo, E.; Lanzano, G.; Pagano, A.; Sperduto, M.L.; Matsuse, T.; Sanders, S.J.

    1991-12-31

    The properties of the fully damped (deep-inelastic and orbiting) and fusion (evaporation and fission) processes have been investigated in three entrance channels leading to the same {sup 47} V compound nucleus at high excitation energies. No entrance channel effect has been observed in either the evaporation residue or the fission-like yields in contrast to the {sup 28}Si + {sup 12}C and {sup 24}Mg + {sup 16}O reactions in which the orbiting process still persists. The asymmetrical elemental distributions of the fully energy relaxed fragments are well described by fusion-fission models based respectively on the scission point and saddle point pictures. Finally a general discussion of the competition between orbiting and fusion-fission mechanisms in light heavy-ion reactions is presented in the framework of their calculated available number of open channels.

  7. Centrifugal inhibitory processes affecting neurones in the cat cochlear nucleus

    PubMed Central

    Comis, S. D.

    1970-01-01

    1. Stimulation of the lateral part of the olivary S-segment in the cat inhibited neurones in the ipsilateral cochlear nucleus. A smaller number of neurones located in the ventral division of the cochlear nucleus were excited. 2. It is suggested that inhibition in the ipsilateral cochlear nucleus may be mediated directly by fibres making synaptic connexions on the cochlear nucleus neurones, or indirectly by inhibitory fibres acting at the cochlea. 3. The direct inhibitory process at the cochlear nucleus is unaffected by strychnine, whereas the inhibitory process at the cochlea is abolished by strychnine. 4. A cochlear nucleus neurone can be influenced simultaneously by excitatory and inhibitory processes. ImagesFig. 1 PMID:5499823

  8. A search for ϕ meson nucleus bound state using antiproton annihilation on nucleus

    NASA Astrophysics Data System (ADS)

    Ohnishi, H.; Bühler, P.; Cargnelli, M.; Curceanu, C.; Guaraldo, C.; Hartmann, O.; Hicks, K.; Iwasaki, M.; Ishiwatari, T.; Kienle, P.; Marton, J.; Muto, R.; Naruki, M.; Niiyama, M.; Noumi, H.; Okada, S.; Vidal, A. Romero; Sakaguchi, A.; Sakuma, F.; Sawada, S.; Sirghi, D.; Sirghi, F.; Suzuki, K.; Tsukada, K.; Doce, O. Vazquez; Widmann, E.; Yokkaichi, S.; Zmeskal, J.

    The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. In 2007, KEK-PS E325 experiment reported about 3.4 % mass reduction of the ϕ meson in medium-heavy nuclei (Cu). This result is possibly one of the indications of the partial restoration of chiral symmetry in nuclei, however, unfortunately it is hard to make strong conclusions from the data. One of the ways to conclude the strength of the ϕ meson mass shift in nuclei will be by trying to produce only slowly moving ϕ mesons where the maximum nuclear matter effect can be probed. The observed mass reduction of the ϕ meson in the nucleus can be translated as the existence of an attractive force between ϕ meson and nucleus. Thus, one of the extreme conditions that can be achieved in the laboratory is indeed the formation of a ϕ-nucleus bound state, where the ϕ meson is "trapped" in the nucleus. The purpose of the experiment is to search for a ϕ-nucleus bound state and measure the binding energy of the system. We will demonstrate that a completely background-free missing-mass spectrum can be obtained efficiently by (bar{p}, φ) spectroscopy together with K + Λ tagging, using the primary reaction channel bar{p} p rightarrow φ φ. This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort.

  9. A search for ϕ meson nucleus bound state using antiproton annihilation on nucleus

    NASA Astrophysics Data System (ADS)

    Ohnishi, H.; Bühler, P.; Cargnelli, M.; Curceanu, C.; Guaraldo, C.; Hartmann, O.; Hicks, K.; Iwasaki, M.; Ishiwatari, T.; Kienle, P.; Marton, J.; Muto, R.; Naruki, M.; Niiyama, M.; Noumi, H.; Okada, S.; Vidal, A. Romero; Sakaguchi, A.; Sakuma, F.; Sawada, S.; Sirghi, D.; Sirghi, F.; Suzuki, K.; Tsukada, K.; Doce, O. Vazquez; Widmann, E.; Yokkaichi, S.; Zmeskal, J.

    2012-12-01

    The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. In 2007, KEK-PS E325 experiment reported about 3.4 % mass reduction of the ϕ meson in medium-heavy nuclei (Cu). This result is possibly one of the indications of the partial restoration of chiral symmetry in nuclei, however, unfortunately it is hard to make strong conclusions from the data. One of the ways to conclude the strength of the ϕ meson mass shift in nuclei will be by trying to produce only slowly moving ϕ mesons where the maximum nuclear matter effect can be probed. The observed mass reduction of the ϕ meson in the nucleus can be translated as the existence of an attractive force between ϕ meson and nucleus. Thus, one of the extreme conditions that can be achieved in the laboratory is indeed the formation of a ϕ-nucleus bound state, where the ϕ meson is "trapped" in the nucleus. The purpose of the experiment is to search for a ϕ-nucleus bound state and measure the binding energy of the system. We will demonstrate that a completely background-free missing-mass spectrum can be obtained efficiently by (bar{p}, φ) spectroscopy together with K + Λ tagging, using the primary reaction channel bar{p} p rightarrow φ φ. This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort.

  10. New measurements of the astrophysical S factor for {sup 12}C(p,{gamma}){sup 13}N reaction at low energies and the asymptotic normalization coefficient (nuclear vertex constant) for the p+{sup 12}C{yields}{sup 13}N reaction

    SciTech Connect

    Burtebaev, N.; Zazulin, D. M.; Igamov, S. B.; Yarmukhamedov, R.; Peterson, R. J.

    2008-09-15

    New measurements of differential and total cross sections for the {sup 12}C(p,{gamma}){sup 13}N reaction have been made at beam energies of E{sub p}=354,390,460,463,565,750, and 1061 keV. Analysis of the astrophysical S factor S(E) for the {sup 12}C(p,{gamma}){sup 13}N reaction at low energies and of the reaction rates has been carried out within the R-matrix approach by using the previously measured nuclear vertex constant (or the respective asymptotic normalization coefficient) for the virtual decay {sup 13}N{yields}p+{sup 12}C to fix the direct capture part of the amplitude in S(E). It is demonstrated that the R-matrix approach, using the measured asymptotic normalization coefficient, can be employed as an ideal tool, minimizing the uncertainties associated with a calculation of the direct capture cross section of the {sup 12}C(p,{gamma}){sup 13}N reaction at extremely low energies. New information on the proton and {gamma} width for the first excited state of {sup 13}N is obtained.

  11. Physical role for the nucleus in cell migration

    NASA Astrophysics Data System (ADS)

    Fruleux, Antoine; Hawkins, Rhoda J.

    2016-09-01

    Cell migration is important for the function of many eukaryotic cells. Recently the nucleus has been shown to play an important role in cell motility. After giving an overview of cell motility mechanisms we review what is currently known about the mechanical properties of the nucleus and the connections between it and the cytoskeleton. We also discuss connections to the extracellular matrix and mechanotransduction. We identify key physical roles of the nucleus in cell migration.

  12. Satellite control system nucleus for the Brazilian complete space mission

    NASA Astrophysics Data System (ADS)

    Yamaguti, Wilson; Decarvalhovieira, Anastacio Emanuel; Deoliveira, Julia Leocadia; Cardoso, Paulo Eduardo; Dacosta, Petronio Osorio

    1990-10-01

    The nucleus of the satellite control system for the Brazilian data collecting and remote sensing satellites is described. The system is based on Digital Equipment Computers and the VAX/VMS operating system. The nucleus provides the access control, the system configuration, the event management, history files management, time synchronization, wall display control, and X25 data communication network access facilities. The architecture of the nucleus and its main implementation aspects are described. The implementation experience acquired is considered.

  13. Decrease and conquer: Phacoemulsification technique for hard nucleus cataracts.

    PubMed

    Kim, Hong Kyun

    2009-10-01

    I describe a technique to improve the control and safety of phacoemulsification during hard nucleus cataract surgery. Whereas the goal of the conventional nucleofractis technique is complete fragmentation of the lens, the technique aims to separate the endonuclear core from the epinucleus. This is done in 3 steps: circumferential disassembly, decreasing the central nucleus volume, and conquering the remnant. The technique offers safer and more effective phacoemulsification in patients with hard nucleus cataracts. PMID:19781457

  14. Physical role for the nucleus in cell migration.

    PubMed

    Fruleux, Antoine; Hawkins, Rhoda J

    2016-09-14

    Cell migration is important for the function of many eukaryotic cells. Recently the nucleus has been shown to play an important role in cell motility. After giving an overview of cell motility mechanisms we review what is currently known about the mechanical properties of the nucleus and the connections between it and the cytoskeleton. We also discuss connections to the extracellular matrix and mechanotransduction. We identify key physical roles of the nucleus in cell migration. PMID:27406341

  15. Thalamic reticular nucleus in Caiman crocodilus: forebrain connections.

    PubMed

    Pritz, Michael B

    2016-08-01

    Forebrain connections of the thalamic reticular nucleus associated with the lateral forebrain bundle were analyzed in Caiman crocodilus. Both the compact portion, the dorsal peduncular nucleus, and the diffuse part, the perireticular region, associated with the lateral forebrain bundle, were studied. A small tracer injection into the dorsal peduncular nucleus demonstrated reciprocal connections with a restricted portion of the dorsal thalamus. Tracer placements into this nucleus retrogradely labeled cells in a caudal portion of the ventrolateral area of the telencephalon. These results are compared with similar studies in other amniotes. PMID:27233216

  16. Giant Resonances in the Alpha-Nucleus Interaction

    SciTech Connect

    Karpeshin, F. F.

    2010-04-30

    Tunneling of alpha particles through the Coulomb barrier for the source {sup 135}Pr nucleus is consecutively considered. The effect of sharp peaks arising in the case of coincidence of the alpha energy with that of a quasistationary state within the barrier is elucidated. Peaks' energy depend on the alpha-nucleus potential. They can give rise to 'anomalous' properties of some neutron resonances. The peaks can also be observed in the incoming alpha-nucleus channel. The method can be applied for solution of the reverse problem of the alpha-nucleus scattering.

  17. Influence of the Coulomb field of the nucleus on the ratio of the yields of charged photopions

    SciTech Connect

    Tonapetyan, S.G.; Khvorostyan, V.M.; Vinokurov, E.A.; Nikitin, V.A.; Shebeko, A.V.

    1982-05-01

    We have measured the energy spectra of charged pions emitted at an angle theta/sub lab/ = 90/sup 0/ in interaction of photons with E/sup max//sub ..gamma../ = 400 MeV with the nuclei /sup 6/Li, /sup 12/C, /sup 24/Mg, /sup 28/Si, and /sup 40/Ca. The particles were recorded by means of a Freon bubble chamber in the energy range E/sub ..pi../ = 45--105 MeV. It was found that the maxima of the spectra of ..pi../sup -/ mesons are shifted relative to the maxima of ..pi../sup +/ mesons by approximately twice the magnitude of the Coulomb potential at the surface of the nucleus. Calculations carried out with Hartree-Fock wave functions for the nuclei /sup 12/C and /sup 40/Ca showed that the shifts of the pion spectra in energy are determined to a substantial degree by the shift of the neutron and proton levels in the nuclei.

  18. Decay of the excited compound system 48Cr* formed through 24Mg + 24Mg , 36Ar + 12C and 20Ne + 28Si reactions

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Subha, P. V.; Priyanka, B.

    2016-05-01

    The total cross section, the intermediate mass fragment (IMF) production cross section, and the cross section for the formation of light particle (LP) for the decay of 48Cr* formed through the entrance channel 24Mg + 24Mg , have been evaluated using the barrier penetration model, taking the scattering potential as the sum of the Coulomb and nuclear proximity potential, for various ECM values. The computed results have been compared with the available experimental data of the total cross section corresponding to E CM = 44.4 MeV for the entrance channel 24Mg + 24Mg , and were found to be in good agreement. The experimental values for the LP production cross section for the channel 24Mg + 24Mg were also seen to be agreeing with our calculations. Hence we have extended our studies and have thus computed the total cross section, IMF cross section and LP cross section for the decay of 48Cr* formed through the other two entrance channels 36Ar + 12C , and 20Ne + 28Si with different ECM values. It was found that the computed total cross sections for the entrance channel 36Ar + 12C with E CM = 47 MeV agree well with the corresponding experimental values. Hence, we hope that our predictions on the evaluations of the IMF cross sections and the light charged particle cross sections for the decay of 48Cr* , formed through the two entrance channels 36Ar + 12C , and 20Ne + 28Si , can be used for further experimental studies.

  19. Effects of mutant human Ki-ras{sup G12C} gene dosage on murine lung tumorigenesis and signaling to its downstream effectors

    SciTech Connect

    Dance-Barnes, Stephanie T.; Kock, Nancy D.; Floyd, Heather S.; Moore, Joseph E.; Mosley, Libyadda J.; D'Agostino, Ralph B.; Pettenati, Mark J.; Miller, Mark Steven

    2008-08-15

    Studies in cell culture have suggested that the level of RAS expression can influence the transformation of cells and the signaling pathways stimulated by mutant RAS expression. However, the levels of RAS expression in vivo appear to be subject to feedback regulation, limiting the total amount of RAS protein that can be expressed. We utilized a bitransgenic mouse lung tumor model that expressed the human Ki-ras{sup G12C} allele in a tetracycline-inducible, lung-specific manner. Treatment for 12 months with 500 {mu}g/ml of doxycycline (DOX) allowed for maximal expression of the human Ki-ras{sup G12C} allele in the lung, and resulted in the development of focal hyperplasia and adenomas. We determined if different levels of mutant RAS expression would influence the phenotype of the lung lesions. Treatment with 25, 100 and 500 {mu}g/ml of DOX resulted in dose-dependent increases in transgene expression and tumor multiplicity. Microscopic analysis of the lungs of mice treated with the 25 {mu}g/ml dose of DOX revealed infrequent foci of hyperplasia, whereas mice treated with the 100 and 500 {mu}g/ml doses exhibited numerous hyperplastic foci and also adenomas. Immunohistochemical and RNA analysis of the downstream effector pathways demonstrated that different levels of mutant RAS transgene expression resulted in differences in the expression and/or phosphorylation of specific signaling molecules. Our results suggest that the molecular alterations driving tumorigenesis may differ at different levels of mutant Ki-ras{sup G12C} expression, and this should be taken into consideration when inducible transgene systems are utilized to promote tumorigenesis in mouse models.

  20. THE {sup 12}C/{sup 13}C RATIO ON TITAN FROM CASSINI INMS MEASUREMENTS AND IMPLICATIONS FOR THE EVOLUTION OF METHANE

    SciTech Connect

    Mandt, Kathleen E.; Waite, J. Hunter; Teolis, Benjamin; Magee, Brian A.; Bell, Jared; Westlake, Joseph H.; Nixon, Conor A.; Mousis, Olivier

    2012-04-20

    We have re-evaluated the Cassini Ion Neutral Mass Spectrometer (INMS) {sup 12}C/{sup 13}C ratios in the upper atmosphere of Titan based on new calibration sensitivities and an improved model for the NH{sub 3} background in the {sup 13}CH{sub 4} mass channel. The INMS measurements extrapolated to the surface give a {sup 12}C/{sup 13}C in CH{sub 4} of 88.5 {+-} 1.4. We compare the results to a revised ratio of 91.1 {+-} 1.4 provided by the Huygens Gas Chromatograph Mass Spectrometer and 86.5 {+-} 7.9 provided by the Cassini Infrared Spectrometer and determine implications of the revised ratios for the evolution of methane in Titan's atmosphere. Because the measured {sup 12}C/{sup 13}C is within the probable range of primordial values, we can only determine an upper boundary for the length of time since methane began outgassing from the interior, assuming that outgassing of methane (e.g., cryovolcanic activity) has been continuous ever since. We find that three factors play a crucial role in this timescale: (1) the escape rate of methane, (2) the difference between the current and initial ratios and the rate of methane, and (3) production or resupply due to cryovolcanic activity. We estimate an upper limit for the outgassing timescale of 470 Myr. This duration can be extended to 940 Myr if production rates are large enough to counteract the fractionation due to escape and photochemistry. There is no lower limit to the timescale because the current ratios are within the range of possible primordial values.

  1. The effect of heavy ion 12C6+on the change of telomerase activity of the human hepatocellular cells and carcinoma cells

    NASA Astrophysics Data System (ADS)

    Dang, Bingrong

    The effect of heavy ion 12C6+on the change of telomerase activity of the human hepatocellular cells and carcinoma cells Dang Bingrong ,Hu Kaiqian (Institute of Modern Physics Chinese Academy of Sciences£¬Graduate University of Chinese Academy of Sciences lanzhou 730000) Abstract Objective To investigate the changes in telomerase and its activity in human tumor and normal cell after exposure of the cells to heavy ion radiation.Irradiation was performed at the Heavy Ion Researsh Facility in Lanzhou (HIRFL). Methods We use the hepatocellular cells HL-7702 and the hepatocellular carcinoma cells SMMC-7721 from the people to experiment. Cells were exposed to 12 C6+ irradiation at 0,1,2,3 and 4Gy. The hepatocellular cells HL-7702 exposed to 12 C6+ irradiation were re-cultured for 72 hours. The hepatocellular carcinoma cells SMMC-7721 were re-cultured for 24 hours and 72 hours. PCR based telomeric repeat amplification protocol(TRAP-PCR) method were used to determine the telomerase activity in SMMC-7721and HL-7702, respectively. Result HL-7702 cells didn't have telomerase. But the cells exposed to 2Gy and 3Gy have the telomerase activity, the cells exposed to 1Gy and 4Gy didn't have the telomerase activity. After exposure to heavy ionizing radiation 1-3Gy the telomerase activity in SMMC-7721 cells were significantly increased in a dose-and timedependent manner. The cells of 7721 exposed to 4Gy was significantly lower than that 0Gy cells. Conclusion Heavy ionizing radiation, as a high LET radiation,induces the increase in telomerase activity in low dose and the decrease in high dose. It indicates that telomerase participates in the repair process of DNA injury induced by heavy ionizing radiation. Key words telomerase heavy ion hepatocellular cells SMMC-7721 cells HL-7702 cells PCR- telomeric repeat amplification protocol

  2. Hydrothermal synthesis of Li{sub 4}Ti{sub 5}O{sub 12}/C nanostructured composites: Morphology and electrochemical performance

    SciTech Connect

    Vujković, Milica; Stojković, Ivana; Mitrić, Miodrag; Mentus, Slavko; Cvjetićanin, Nikola

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Nanostructured composite Li{sub 4}Ti{sub 5}O{sub 12}/C was obtained hydrothermally. ► The amount of carbon black influenced significantly the morphology of the composite. ► Rate capability of Li{sub 4}Ti{sub 5}O{sub 12} was improved by the synthesis in presence of carbon black. ► Coulombic capacity of 150 mAh g{sup −1} was obtained at a discharging rate of even 10 C. -- Abstract: Li{sub 4}Ti{sub 5}O{sub 12}/C composites with low (3 wt.%) and high (33 wt.%) carbon black content as well as carbon-free Li{sub 4}Ti{sub 5}O{sub 12} were prepared in two steps under identical conditions: hydrothermal reaction at 130 °C and post-calcination at 400 °C. The X-ray diffraction experiments confirmed the spinel structure of Li{sub 4}Ti{sub 5}O{sub 12} in all samples. The carbon content altered significantly the morphology of obtained micro/nanoparticles. The Li{sub 4}Ti{sub 5}O{sub 12}/C composite with the high carbon content showed the highest electrical conductivity (2.0 S cm{sup −1}), and displayed also extraordinary electrochemical performance: the cyclovoltammograms consisted of well defined reversible redox peaks at a scan rate as high as 10 mV s{sup −1}, while, by galvanostatic cycling, the coulombic capacity of 150 mAh g{sup −1} was evidenced at a discharging rate of 10 C.

  3. Assessment of experimental d-PIGE γ-ray production cross sections for 12C, 14N and 16O and comparison with absolute thick target yields

    NASA Astrophysics Data System (ADS)

    Csedreki, L.; Halász, Z.; Kiss, Á. Z.

    2016-08-01

    Measured differential cross sections for deuteron induced γ-ray emission from the reactions 12C(d,pγ)13C, (Eγ = 3089 keV), 14N(d,pγ)15N (Eγ = 8310 keV) and 16O(d,pγ)17O (Eγ = 871 keV) available in the literature were assessed. In order to cross check the assessed γ-ray production cross section data, thick target γ-yields calculated from the differential cross sections were compared with available measured thick target yields. Recommended differential cross section data for each reaction were deduced for particle induced γ-ray emission (PIGE) applications.

  4. Indirect Measurement of {sup 15}N(p,{alpha}){sup 12}C and {sup 18}O(p,{alpha}){sup 15}N. Applications to the AGB Star Nucleosynthesis

    SciTech Connect

    La Cognata, M.; Spitaleri, C.; Cherubini, S.; Crucilla, V.; Gulino, M.; Lamia, L.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Tumino, A.; Tribble, R.; Al-Abdullah, T.; Banu, A.; Fu, C.; Goldberg, V.; Mukhamedzhanov, A.; Tabacaru, G.; Trache, L.

    2008-04-06

    The Trojan Horse Method has been recently applied to the study of reactions involved in fluorine nucleosynthesis inside AGB stars. Fluorine abundance is important since it allows to constrain mixing models from the comparison of the observed fluorine abundances with the ones predicted by models. Anyway direct measurements of the cross section do not extend down to the Gamow peak, which is the astrophysically relevant energy region. In particular the study focuses on the {sup 15}N(p,{alpha}){sup 12}C and the {sup 18}O(p,{alpha}){sup 15}N reactions which can influence fluorine yield as they are part of {sup 19}F production/destruction network.

  5. Temperature and Pressure Studies of the Reactions of CH3O2, HO2, and 1,2-C4H9O2 with NO2.

    PubMed

    McKee, Kenneth; Blitz, Mark A; Pilling, Michael J

    2016-03-10

    A novel technique has been developed for the detection of peroxy radicals in order to study their kinetics with NO2. Peroxy radicals (RO2, where R = H, CH3, and 1,2-C4H9) were produced by laser flash photolysis and were probed by photodissociation of the RO2 and the subsequent detection of either OH or CH3O photofragments by laser-induced fluorescence. Reaction 1 , CH3O2 + NO2 + M ⇌ CH3O2NO2 + M (M = N2), was studied between 25 and 400 Torr at 295 K, giving results in excellent agreement with the literature. At temperatures between 333 and 363 K, equilibration was observed and yielded ΔrH(⊖)298(1) = -93.5 ± 0.3 kJ mol(-1). Reaction 2, HO2 + NO2 + M ⇌ HO2NO2 + M (M = N2), was studied at 295 K and showed kinetics in fair agreement with the literature. Equilibration at higher temperatures was obscured by an additional loss of HO2NO2 from the system. In addition, the OH quantum yield from photolysis of HO2NO2 at 248 nm was determined to be 0.15 ± 0.03. Reaction 3 , 1,2-C4H9O2 + NO2 + M ⇌ 1,2-C4H9O2NO2 + M (M = He), was studied between 241 and 341 K, and at the higher temperatures equilibration was observed, which yielded ΔrH(⊖)298(3) = -93.5 ± 0.6 kJ mol(-1). The low uncertainties in the enthalpies of formation for both CH3O2 and 1,2-C4H9O2 are a result of using a master equation method that allows global analysis of all the available rate data (present measurements and literature values) for forward and reverse reactions under all conditions of temperature and pressure. PMID:26397023

  6. Comparing modern measurements of the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C excitation function with previous values

    SciTech Connect

    Cooper, Kevin W.; Massey, Thomas N.; Ingram, David C.

    2013-04-19

    A possible means of active interrogation of special nuclear materials is detection of signature emissions following induced photofission. This method requires a probe gamma-ray beam to induce the photofission. The {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction is a candidate for the source of this probe beam. The reaction is prolific and the produced 15.1 MeV gamma-ray is close to a photofission cross-section peak for {sup 235,238}U and {sup 238,239}Pu. In order to model an active interrogation system using the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction as a source probe an accurate value for its differential crosssection must be included in data libraries. Measurements of the differential cross-section for the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction have been carried out with a BGO detector and found to differ from previous measurements reported by Kavanagh (1958) and Kuan (1964). The discrepancy in the measurements may be explained by examining the detector response function used by Kavanagh and presumably Kuan to that modeled with MCNP5. A comparison of the MCNP5 and Kavanagh detector response functions normalized to the 15.1 MeV gamma-ray peak pulse height shows a factor of approximately 1.7 difference in integrated counts. Applying this correction to the differential cross-section previously reported by Kuan brings the values into agreement, within uncertainties, to the more recent measurements. The evaluation of the detector response function for the 15.1 MeV gamma-ray signal in the NaI detector reported by Kavanagh to that modeled by MCNP5 is shown. This result is applied to the comparison of recent measurements on the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction differential cross-section to those previously reported.

  7. Isotope Substitution Effect in Polyatomic Molecules on the Example of 13C2H4 ← 12C2H4 Substitution

    NASA Astrophysics Data System (ADS)

    Bekhtereva, E. S.; Gromova, O. V.; Berezkin, K. B.; Kashirina, N. V.; Konov, I. A.; Bauerecker, S.

    2016-03-01

    General points of the theory of isotope substitution are applied to an analysis of the isotope substitution effect for the substitution 13C2H4←12C2H4 in the ethylene molecule. On the basis of the isotope relations so obtained, numerical predictions of band centers and the most significant rotational, centrifugal, and resonance parameters are made here for the first time for the four lower vibrational states of the 13C2H4 molecule, which can be used to analyze the complicated vibrational-rotational structure of the above-mentioned vibrational states.

  8. Study of the 20,22Ne+20,22Ne and 10,12,13,14,15C+12C Fusion Reactions with MUSIC

    NASA Astrophysics Data System (ADS)

    Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.; Carnelli, P. F. F.; DiGiovine, B.; Esbensen, H.; Hoffman, C. R.; Jiang, C. L.; Kay, B. P.; Lai, J.; Nusair, O.; Pardo, R. C.; Santiago-Gonzalez, D.; Talwar, R.; Ugalde, C.

    2016-05-01

    A highly efficient MUlti-Sampling Ionization Chamber (MUSIC) detector has been developed for measurements of fusion reactions. A study of fusion cross sections in the 10,12,13,14,15C+12C and 20,22Ne+20,22Ne systems has been performed at ATLAS. Experimental results and comparison with theoretical predictions are presented. Furthermore, results of direct measurements of the 17O(α, n)20Ne, 23Ne(α, p)26Mg and 23Ne(α, n)26Al reactions will be discussed.

  9. Determination of astrophysical thermonuclear rates with a bubble chamber: The {sup 12}C(αγ){sup 16}O reaction case

    SciTech Connect

    DiGiovine, B.; Henderson, D.; Holt, R. J.; Rehm, K. E.; Grames, J.; Meekins, D.; Poelker, M.; Suleiman, R.; Robinson, A.; Ugalde, C.; Sonnenschein, A.

    2013-11-07

    The {sup 12}C(αγ){sup 16}O reaction rate is considered one of the most important unknown parameters in the physics of structure and evolution of massive stars. While extensive experimental campaigns have been performed trying to improve the quality of the measurements, the rate still holds very large uncertainties. Here we discuss a new experimantal scheme to measure the cross section of this reaction with a bubble chamber and a bremsstrahlung beam. The main advantage of the technique is a gain in the luminosity of several orders of magnitude when compared to other ongoing experiments.

  10. An optical model analysis of /sup 16/O + /sup 12/C elastic scattering at E/A = 94 MeV

    SciTech Connect

    Kobos, A.M.; Satchler, G.R.

    1987-01-01

    An analysis of experimental data for /sup 16/O + /sup 12/C elastic scattering at an /sup 16/O bombarding energy of 1503 MeV is presented, including the use of ''model-independent'' and ''semi-model-independent'' techniques. The data unambiguously indicate an optical potential whose real part is approximately 80 MeV deep in the interior, but which is more attractive in the surface region than that given by a folding model with a ''realistic'' nucleon-nucleon interaction. 6 refs., 3 figs., 1 tab.

  11. Implementation of a Novel Laser System for Simultaneous Measurement of 13C/12C and D/H to Food Provenance

    NASA Astrophysics Data System (ADS)

    Saad, N.; Hoffnagle, J.

    2012-04-01

    Olive oil samples were analyzed using the world's first simultaneous δ13C + δD instrument, the 13C+D Combustion Module-Cavity Ringdown Spectroscopy (CM-CRDS) Isotope Analyzer. Simultaneous measurements of δ13C and δD of the whole oil have been performed on commercially available olive oils produced in Greece, Spain, Italy, California, Lebanon, Israel, Australia and Turkey. Together, the measurements of isotopic ratios of carbon (13C/12C) and hydrogen (D/H) produce statistically significant differentiation between olive oils from different locations around the globe. Stable isotope ratios are exquisitely sensitive to the biochemistry of plant species and the nutrients available to them in a particular geographical location. Isotope ratios provide detailed knowledge useful for forensic applications through a combination of stable-isotope measurements of carbon (13C/12C) and hydrogen (D/H) isotopes of organic matter and can help the associations among specific geographic areas through the measurement of these dual isotopes. We report here on the development of a novel laser spectroscopy based system for the simultaneous analysis of the stable isotope ratios of carbon (13C/12C) and hydrogen (D/H) that is robust, easy-to-use, and is the first stable isotope ratio analysis system to combine the measurement of 13C/12C and D/H in one simple analysis from a bulk organic sample. The system comprises a combustion module to convert the organic sample into CO2 and H2O and a Cavity Ring-Down Spectrometer (CRDS) that analyzes the combustion species inside an optical cavity based on the molecular absorption of individual isotopomers. The CRDS uses dual lasers to target the four isotpomers of interest: 12CO2, 13CO2, H2O and HDO. The system delivers a typical precision of 0.1permil for δ13C and 1.5 permil for δD that parallels that achieved by IRMS, but with an unprecedented simplicity that allows scientists to leverage the science and map out the provenance of the analyzed

  12. Measurements of fusion reactions of low-intensity radioactive carbon beams on 12C and their implications for the understanding of X-ray bursts.

    PubMed

    Carnelli, P F F; Almaraz-Calderon, S; Rehm, K E; Albers, M; Alcorta, M; Bertone, P F; Digiovine, B; Esbensen, H; Niello, J O Fernández; Henderson, D; Jiang, C L; Lai, J; Marley, S T; Nusair, O; Palchan-Hazan, T; Pardo, R C; Paul, M; Ugalde, C

    2014-05-16

    The interaction between neutron-rich nuclei plays an important role for understanding the reaction mechanism of the fusion process as well as for the energy production through pycnonuclear reactions in the crust of neutron stars. We have performed the first measurements of the total fusion cross sections in the systems (10,14,15)C+(12)C using a new active target-detector system. In the energy region accessible with existing radioactive beams, a good agreement between the experimental and theoretical cross sections is observed. This gives confidence in our ability to calculate fusion cross sections for systems which are outside the range of today's radioactive beam facilities. PMID:24877935

  13. Analysis of Returned Comet Nucleus Samples

    NASA Astrophysics Data System (ADS)

    Chang, Sherwood

    1997-12-01

    This volume contains abstracts that have been accepted by the Program Committee for presentation at the Workshop on Analysis of Returned Comet Nucleus Samples, held in Milpitas, California, January 16-18, 1989. Conveners are Sherwood Chang (NASA Ames Research Center) and Larry Nyquist (NASA Johnson Space Center). Program Committee members are Thomas Ahrens (ex-officio; California Institute of Technology), Lou Allamandola (NASA Ames Research Center), David Blake (NASA Ames Research Center), Donald Brownlee (University of Washington, Seattle), Theodore E. Bunch (NASA Ames Research Center), Humberto Campins (Planetary Science Institute), Jeff Cuzzi (NASA Ames Research Center), Eberhard Griin (Max-Plank-Institut fiir Kemphysik), Martha Hanner (Jet Propulsion Laboratory), Alan Harris (Jet Propulsion Laboratory), John Kerrid-e (University of Califomia, Los Angeles), Yves Langevin (University of Paris), Gerhard Schwehm (ESTEC), and Paul Weissman (Jet Propulsion Laboratory). Logistics and administrative support for the workshop were provided by the Lunar and Planetary Institute Projects Office.

  14. Analysis of Returned Comet Nucleus Samples

    NASA Technical Reports Server (NTRS)

    Chang, Sherwood (Compiler)

    1997-01-01

    This volume contains abstracts that have been accepted by the Program Committee for presentation at the Workshop on Analysis of Returned Comet Nucleus Samples, held in Milpitas, California, January 16-18, 1989. Conveners are Sherwood Chang (NASA Ames Research Center) and Larry Nyquist (NASA Johnson Space Center). Program Committee members are Thomas Ahrens (ex-officio; California Institute of Technology), Lou Allamandola (NASA Ames Research Center), David Blake (NASA Ames Research Center), Donald Brownlee (University of Washington, Seattle), Theodore E. Bunch (NASA Ames Research Center), Humberto Campins (Planetary Science Institute), Jeff Cuzzi (NASA Ames Research Center), Eberhard Griin (Max-Plank-Institut fiir Kemphysik), Martha Hanner (Jet Propulsion Laboratory), Alan Harris (Jet Propulsion Laboratory), John Kerrid-e (University of Califomia, Los Angeles), Yves Langevin (University of Paris), Gerhard Schwehm (ESTEC), and Paul Weissman (Jet Propulsion Laboratory). Logistics and administrative support for the workshop were provided by the Lunar and Planetary Institute Projects Office.

  15. Suprachiasmatic Nucleus: Cell Autonomy and Network Properties

    PubMed Central

    Welsh, David K.; Takahashi, Joseph S.; Kay, Steve A.

    2013-01-01

    The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals. Individual SCN neurons in dispersed culture can generate independent circadian oscillations of clock gene expression and neuronal firing. However, SCN rhythmicity depends on sufficient membrane depolarization and levels of intracellular calcium and cAMP. In the intact SCN, cellular oscillations are synchronized and reinforced by rhythmic synaptic input from other cells, resulting in a reproducible topographic pattern of distinct phases and amplitudes specified by SCN circuit organization. The SCN network synchronizes its component cellular oscillators, reinforces their oscillations, responds to light input by altering their phase distribution, increases their robustness to genetic perturbations, and enhances their precision. Thus, even though individual SCN neurons can be cell-autonomous circadian oscillators, neuronal network properties are integral to normal function of the SCN. PMID:20148688

  16. The Bivalent Side of the Nucleus Accumbens

    PubMed Central

    Levita, Liat; Hare, Todd A.; Voss, Henning U.; Glover, Gary; Ballon, Douglas J.; Casey, B.J.

    2009-01-01

    An increasing body of evidence suggests that the nucleus accumbens (NAcc) is engaged in both incentive reward processes and in adaptive responses to conditioned and unconditioned aversive stimuli. Yet, it has been argued that NAcc activation to aversive stimuli may be a consequence of the rewarding effects of their termination, i.e., relief. To address this question we used fMRI to delineate brain response to the onset and offset of unpleasant and pleasant auditory stimuli in the absence of learning or motor response. Increased NAcc activity was seen for the onset of both pleasant and unpleasant stimuli. Our results support the expanded bivalent view of NAcc function and call for expansion of current models of NAcc function that are solely focused on reward. PMID:18976715

  17. Nature of multiple-nucleus cluster galaxies

    SciTech Connect

    Merritt, D.

    1984-05-01

    In models for the evolution of galaxy clusters which include dynamical friction with the dark binding matter, the distribution of galaxies becomes more concentrated to the cluster center with time. In a cluster like Coma, this evolution could increase by a factor of approximately 3 the probability of finding a galaxy very close to the cluster center, without decreasing the typical velocity of such a galaxy significantly below the cluster mean. Such an enhancement is roughly what is needed to explain the large number of first-ranked cluster galaxies which are observed to have extra ''nuclei''; it is also consistent with the high velocities typically measured for these ''nuclei.'' Unlike the cannibalism model, this model predicts that the majority of multiple-nucleus systems are transient phenomena, and not galaxies in the process of merging.

  18. Isotopic microanalysis of returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Zinner, Ernst

    1989-01-01

    If isotopic measurements of interplanetary dust particles (IDPs) and primitive meteorites can serve as a guide to the isotopic analysis of returned comet nucleus material, an essential requirement will be the capability for microanalysis. The reason is that in both types of extraterrestrial samples large isotopic heterogeneities on a small spatial scale have become apparent once it was possible to measure isotopes in small samples. In the discovery of large isotopic anomalies the ion microprobe has played a significant role because of its high spatial resolution for isotopic ratio measurements. The largest isotopic anomalies in C, N, O, Mg, Si, Ca and Ti found to date were measured by ion microprobe mass spectrometry. The most striking examples are D/H measurements in IDPs and isotopic measurements of C, N and Si in SiC from the CM chondrites Murray and Murchison.

  19. Delta-nucleus dynamics: proceedings of symposium

    SciTech Connect

    Lee, T.S.H.; Geesaman, D.F.; Schiffer, J.P.

    1983-10-01

    The appreciation of the role in nuclear physics of the first excited state of the nucleon, the delta ..delta..(1232), has grown rapidly in the past decade. The delta resonance dominates nuclear reactions induced by intermediate energy pions, nucleons, and electromagnetic probes. It is also the most important non-nucleonic degree of freedom needed to resolve many fundamental problems encountered in the study of low-energy nuclear phenomena. Clearly, a new phase of nuclear physics has emerged and conventional thinking must be extended to account for this new dimension of nuclear dynamics. The most challenging problem we are facing is how a unified theory can be developed to describe ..delta..-nucleus dynamics at all energies. In exploring this new direction, it is important to have direct discussions among researchers with different viewpoints. Separate entries were prepared for the 49 papers presented. (WHK)

  20. Retrotrapezoid nucleus, respiratory chemosensitivity and breathing automaticity

    PubMed Central

    Guyenet, Patrice G.; Bayliss, Douglas A.; Stornetta, Ruth L.; Fortuna, Michal G.; Abbott, Stephen B.; Depuy, Seth D.

    2009-01-01

    SUMMARY Breathing automaticity and CO2 regulation are inseparable neural processes. The retrotrapezoid nucleus (RTN), a group of glutamatergic neurons that express the transcription factor Phox2b, may be a crucial nodal point through which breathing automaticity is regulated to maintain CO2 constant. This review updates the analysis presented in prior publications. Additional evidence that RTN neurons have central respiratory chemoreceptor properties is presented but this is only one of many factors that determine their activity. The RTN is also regulated by powerful inputs from the carotid bodies and, at least in the adult, by many other synaptic inputs. We also analyze how RTN neurons may control the activity of the downstream central respiratory pattern generator. Specifically, we review the evidence which suggests that RTN neurons a) innervate the entire ventral respiratory column, and b) control both inspiration and expiration. Finally, we argue that the RTN neurons are the adult form of the parafacial respiratory group in neonate rats. PMID:19712903

  1. Nucleus of Comet P/Arend-Rigaux

    SciTech Connect

    Brooke, T.Y.; Knacke, R.F.

    1986-07-01

    Photometry data at 1-20 microns taken of Comet P/Arend-Rigaux are reported. The observations were carried out to test the possibility of observing the nuclei of low activity, nearly extinct comets at visible and IR wavelengths. The data were collected in February 1985 using the NASA 3 m IR telescope on Mauna Kea. The comet was at 1.67 AU heliocentric distance at the time. Attempts were made to detect rotation of the core on the bases of variations in the J, H and K light curves. The images obtained were those of a rotating nucleus with a radius of 4.0-6.2 km surrounded by a faint coma. The comet had a geometric albedo of 0.01-0.03 and a near-IR red slope that exhibited no evidence of the presence of ice. 32 references.

  2. Nonlinear osmotic properties of the cell nucleus

    PubMed Central

    Finan, John D.; Chalut, Kevin J.; Wax, Adam; Guilak, Farshid

    2009-01-01

    Summary In the absence of active volume regulation processes, cell volume is inversely proportional to osmolarity, as predicted by the Boyle Van’t Hoff relation. In this study, we tested the hypothesis that nuclear volume has a similar relationship with extracellular osmolarity in articular chondrocytes, cells that are exposed to changes in the osmotic environment in vivo, and furthermore, we explored the mechanism of the relationships between osmolarity and nuclear size and shape. Nuclear size was quantified using two independent techniques, confocal laser scanning microscopy and angle-resolved low coherence interferometry. Nuclear volume was osmotically-sensitive but this relationship was not linear, showing a decline in the osmotic sensitivity in the hypo-osmotic range. Nuclear shape was also influenced by extracellular osmolarity, becoming smoother as the osmolarity decreased. The osmotically-induced changes in nuclear size paralleled the changes in nuclear shape, suggesting that shape and volume are interdependent. The osmotic sensitivity of shape and volume persisted after disruption of the actin cytoskeleton. Isolated nuclei contracted in response to physiologic changes in macromolecule concentration but not in response to physiologic changes in ion concentration, suggesting solute size has an important influence on the osmotic pressurization of the nucleus. This finding in turn implies that the diffusion barrier that causes osmotic effects is not a semi-permeable membrane, but rather due to size constraints that prevent large solute molecules from entering small spaces in the nucleus. As nuclear morphology has been associated previously with cell phenotype, these findings may provide new insight into the role of mechanical and osmotic signals in regulating cell physiology. PMID:19107599

  3. Recent developments in the study of deconfinement in nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Gazdzicki, M.; Gorenstein, M. I.; Seyboth, P.

    2014-05-01

    Deconfinement refers to the creation of a state of quasi-free quarks and gluons in strongly interacting matter. Model predictions and experimental evidence for the onset of deconfinement in nucleus-nucleus collisions were discussed in our first review on this subject. These results motivated further experimental and theoretical studies. This review addresses two subjects. First, a summary of the past, present and future experimental programmes related to discovery and study of properties of the onset of deconfinement are presented. Second, recent progress is reviewed on analysis methods and preliminary experimental results for new strongly intensive fluctuation measures are discussed, which are relevant for current and future studies of the onset of deconfinement and searches for the critical point of strongly interacting matter.

  4. Fluctuation analysis of relativistic nucleus-nucleus collisions in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1988-01-01

    An analytical technique was developed for identifying enhanced fluctuations in the angular distributions of secondary particles produced from relativistic nucleus-nucleus collisions. The method is applied under the assumption that the masses of the produced particles are small compared to their linear momenta. The importance of particles rests in the fact that enhanced fluctuations in the rapidity distributions is considered to be an experimental signal for the creation of the quark-gluon-plasma (QGP), a state of nuclear matter predicted from the quantum chromodynamics theory (QCD). In the approach, Monte Carlo simulations are employed that make use of a portable random member generator that allow the calculations to be performed on a desk-top computer. The method is illustrated with data taken from high altitude emulsion exposures and is immediately applicable to similar data from accelerator-based emulsion exposures.

  5. Dynamical and Statistical Aspects in Nucleus--Nucleus Collisions Around the Fermi Energy

    NASA Astrophysics Data System (ADS)

    Tamain, B.; Assenard, M.; Auger, G.; Bacri, C. O.; Benlliure, J.; Bisquer, E.; Bocage, F.; Borderie, B.; Bougault, R.; Buchet, P.; Charvet, J. L.; Chbihi, A.; Colin, J.; Cussol, D.; Dayras, R.; Demeyer, A.; Dore, D.; Durand, D.; Eudes, P.; Frankland, J.; Galichet, E.; Genouin-Duhamel, E.; Gerlic, E.; Germain, M.; Gourio, D.; Guinet, D.; Gulminelli, F.; Lautesse, P.; Laville, J. L.; Lebrun, C.; Lecolley, J. F.; Lefevre, A.; Lefort, T.; Legrain, R.; Le Neindre, N.; Lopez, O.; Louvel, M.; Lukasik, J.; Marie, N.; Maskay, M.; Metivier, V.; Nalpas, L.; Nguyen, A.; Parlog, M.; Peter, J.; Plagnol, E.; Rahmani, A.; Reposeur, T.; Rivet, M. F.; Rosato, E.; Saint-Laurent, F.; Salou, S.; Squalli, M.; Steckmeyer, J. C.; Stern, M.; Tabacaru, T.; Tassan-Got, L.; Tirel, O.; Vient, E.; Volan, C.; Wieleczko, J. P.

    1998-01-01

    This contribution is devoted to two important aspects of intermediate energy nucleus-nucleus collisions: the competition of dynamical and statistical features, and the origin of the multifragmentation process. These two questions are discussed in focusing on Indra data. It turns out that most of collisions are binary and reminiscent of deep inelastic collisions observed at low energy. However, intermediate velocity emission is a clear signature of dynamical emission and establishes a link with the participant-spectator picture which applies at high bombarding energies. Multifragmentation is observed when the dissipated energy is large and it turns out that expansion occurs at least for central collisions, as it is expected if this phenomenum has a dynamical origin.

  6. Experimental evidence and the Landau-Zener promotion in nucleus-nucleus collisions

    SciTech Connect

    Cindro, N.; Freeman, R.M.; Haas, F.

    1986-04-01

    Recent data from C+O collisions are analyzed in terms of the Landau-Zener promotion in nuclei. Evidence for the presence of this mechanism in nuclear collisions is of considerable interest, since it provides a signature of single-particle orbitals in molecular-type potentials and, at the same time, paves the way to a microscopic understanding of the collision dynamics, in particular of the energy dissipation rate. The analyzed data are of two types: integrated cross sections and angular distributions of inelastically scattered particles. The first set of data shows structure qualitatively consistent with recent calculations of the Landau-Zener effect; for this set of data no other reasonable explanation is presently available. The second set of data, while consistent with the presence of the Landau-Zener promotion, is examined in terms of other possible explanations too. The combined data show evidence favoring the presence of the Landau-Zener promotion in nucleus-nucleus collisions.

  7. Nonmonotonic Target Excitation Dependence of Pion Clans in Relativistic Nucleus-Nucleus Collisions

    NASA Astrophysics Data System (ADS)

    Ghosh, Dipak; Deb, Argha; Dutta, Srimonti

    Target excitation dependence of fluctuation of produced pions (i.e. classifying data of the fluctuation pattern on pions on the basis of the number of gray tracks) is studied for nucleus-nucleus collisions at different projectile energies. In each set the experimental multiplicity distribution is compared with the negative binomial distribution (NBD), which is found to describe the experimental distribution quite well. Target excitation dependence is studied in respect of the clan model parameters bar {n}c and bar {N}, which are extracted from the NBD fit parameters bar {n} and k. A detailed comparison between different interactions at the same energy and the same interactions at different energies is also drawn. A nonmonotonic dependence of D2/bar {n} on is revealed, which is also a characteristic of multiplicity fluctuations at RHIC data.

  8. On the geometric nature of high energy nucleus-nucleus reaction cross sections

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.; Bidasaria, H. B.

    1982-01-01

    Within the context of a high energy double-folding optical potential approximation to the exact nucleus-nucleus multiple-scattering series, eikonal scattering theory is used to investigate the validity of geometric reaction cross sections in relativistic heavy ion collisions. The potential used includes a finite range interaction and nuclear single-particle densities extracted from nuclear charge distributions by unfolding the finite proton charge distribution. Pauli correlation effects are also included in an approximate way. The sensitivity of the predictions to the assumed interaction, Pauli correlation approximation, and nuclear density distributions is investigated. These results are in agreement with early predictions concerning the geometric nature of relativistic heavy ion collisions and in disagreement with a recent analysis, utilizing the zero range approximation, which suggested otherwise. Reasons for the lack of agreement between the analyses are also presented. Finally, approximate applicability limits for geometric reaction cross sections are determined.

  9. Study of the A(e,e'$\\pi^+$) Reaction on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au

    SciTech Connect

    Qian, X; Clasie, B; Arrington, J; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Christy, M E; Chudakov, E; Dalton, M M; Daniel, A; Day, D; Dutta, D; El Fassi, L; Ent, R; Fenker, H C; Ferrer, J; Fomin, N; Gao, H; Garrow, K; Gaskell, D; Gray, C; Huber, G M; Jones, M K; Kalantarians, N; Keppel, C E; Kramer, K; Li, Y; Liang, Y; Lung, A F; Malace, S; Markowitz, P; Matsumura, A; Meekins, D G; Mertens, T; Miyoshi, T; Mkrtchyan, H; Monson, R; Navasardyan, T; Niculescu, G; Niculescu, I; Okayasu, Y; Opper, A K; Perdrisat, C; Punjabi, V; Rauf, A W; Rodriquez, V M; Rohe, D; Seely, J; Segbefia, E; Smith, G R; Sumihama, M; Tadevosyan, V; Tang, L; Villano, A; Vulcan, W F; Wesselmann, F R; Wood, S A; Yuan, L; Zheng, X

    2010-05-01

    Cross sections for the p($e,e'\\pi^{+}$)n process on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au targets were measured at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in order to extract the nuclear transparencies. Data were taken for four-momentum transfers ranging from $Q^2$=1.1 to 4.8 GeV$^2$ for a fixed center of mass energy of $W$=2.14 GeV. The ratio of $\\sigma_L$ and $\\sigma_T$ was extracted from the measured cross sections for $^1$H, $^2$H, $^{12}$C and $^{63}$Cu targets at $Q^2$ = 2.15 and 4.0 GeV$^2$ allowing for additional studies of the reaction mechanism. The experimental setup and the analysis of the data are described in detail including systematic studies needed to obtain the results. The results for the nuclear transparency and the differential cross sections as a function of the pion momentum at the different values of $Q^2$ are presented. Global features of the data are discussed and the data are compared with the results of model calculations for the p($e,e'\\pi^{+}$)n reaction from nuclear targets.

  10. Measurements of the 11B(d,nγ15.1)12C differential cross-section on thick and thin targets

    NASA Astrophysics Data System (ADS)

    Cooper, Kevin W.; Massey, Thomas N.; Carter, D. E.; Ingram, David C.

    2013-06-01

    The differential cross-section for the 15.1 MeV gamma ray produced by the 11B(d,nγ)12C reaction in a thick natural boron target has been measured for incident deuteron energies ranging from reaction threshold to 5 MeV. Measurements for a thin natural boron target have been carried out over a similar incident deuteron energy range. These results are compared to previous measurements made by Kavanagh (1958) and Kuan (1964). Measurements of the combined thick target yield for the 6.129, 6.917, and 7.116 MeV gamma rays from the 19F(p,αγ)16O reaction have been carried out on a stopping thickness sulfur hexafluoride gas cell for effective incident proton energies ranging from 1 to 4 MeV as a consistency check on the procedure used for normalization of the detector response function. The results for the 11B(d,nγ15.1)12C yield a significantly lower cross-section than that previously reported, while the measurements of the 19F(p,αγ) reaction are consistent with previous measurements made by Fessler (2000) and Micklich (2003).

  11. The polar 2e/12c bond in phenalenyl-azaphenalenyl hetero-dimers: Stronger stacking interaction and fascinating interlayer charge transfer

    NASA Astrophysics Data System (ADS)

    Zhong, Rong-Lin; Xu, Hong-Liang; Li, Zhi-Ru

    2016-08-01

    An increasing number of chemists have focused on the two-electron/multicenter bond (2e/mc) that was first introduced to interpret the bonding mechanism of radical dimers. Herein, we report the polar two-electron/twelve center (2e/12c) bonding character in a series of phenalenyl-azaphenalenyl radical hetero-dimers. Interestingly, the bonding energy of weaker polar hetero-dimer (P-TAP) is dominated by the overlap of the two different singly occupied molecular orbital of radicals, while that of stronger polar hetero-dimer (P-HAP) is dominated by the electrostatic attraction. Results show that the difference between the electronegativity of the monomers plays a prominent role in the essential attribution of the polar 2e/12c bond. Correspondingly, a stronger stacking interaction in the hetero-dimer could be effectively achieved by increasing the difference of nitrogen atoms number between the monomers. It is worthy of note that an interesting interlayer charge transfer character is induced in the polar hetero-dimers, which is dependent on the difference between the electronegativity of the monomers. It is our expectation that the new knowledge about the bonding nature of radical hetero-dimers might provide important information for designing radical based functional materials with various applications.

  12. [Effect of accelerated heavy ions of carbon 12C, neon 20Ne and iron 56Fe on the chromosomal apparatus of human blood lymphocytes in vitro].

    PubMed

    Repina, L A

    2011-01-01

    Cytogenetic assay of the chromosomal apparatus of human blood lymphocytes was carried out after in vitro irradiation by heavy charged particles with high LET values. Blood plasm samples enriched with lymphocytes were irradiated by accelerated ions of carbon 12C (290 MeV/nucleon and LET = 70 keV/microm), neon 20Ne (400 MeV/nucleon and LET = 70 keV/microm), and iron 56Fe (500 MeV/nucleon and LET = 200 keV/microm) in the dose range from 0.25 to 1 Gy. Rate of chromosome aberrations showed a linear dependence on doses from the densely ionizing radiations with high LET values. Frequency of dicentrics and centric rings in human lymphocytes irradiated by 12C with the energy of 290 MeV/nucleon was maximal at 1 Gy (p < 0.05) relative to the other heavy particles. It was found that relative biological effectiveness of heavy nuclei is several times higher than of 60Co gamma-radiation throughout the range of doses in this investigation. PMID:22312859

  13. Targeting triple-negative breast cancer cells with 6,7-bis(hydroxymethyl)-1H,3H-pyrrolo[1,2-c]thiazoles.

    PubMed

    Santos, Kathleen; Laranjo, Mafalda; Abrantes, Ana Margarida; Brito, Ana F; Gonçalves, Cristina; Sarmento Ribeiro, Ana Bela; Botelho, M Filomena; Soares, Maria I L; Oliveira, Andreia S R; Pinho e Melo, Teresa M V D

    2014-05-22

    Further studies on 6,7-bis(hydroxymethyl)-1H,3H-pyrrolo[1,2-c]thiazoles as anticancer agents against breast cancer are reported, allowing to demonstrate the potential of these compounds for the therapy of the triple-negative breast cancer, the most challenging tumors in clinical practice. These compounds were assayed for their in vitro cytotoxicity on several human breast cancer cell lines (MCF7, HCC1954 and HCC1806 cell lines). Particularly interesting were the results obtained for 4-hydroxyphenyl substituted derivative, which proved to be the most promising compound regarding HCC1806 cell line, a triple-negative breast cancer. The effects of the two most active compounds on cell survival, viability, cell cycle, DNA damage and expression of proteins related to cell death pathways were studied. The reported results consolidate the potential of 6,7-bis(hydroxymethyl)-1H,3H-pyrrolo[1,2-c]thiazoles for the therapy of breast cancer, particularly the triple-negative. PMID:24747064

  14. Analysis of SRM model nozzle calibration test data in support of IA12B, IA12C and IA36 space shuttle launch vehicle aerodynamics tests

    NASA Technical Reports Server (NTRS)

    Baker, L. R., Jr.; Tevepaugh, J. A.; Penny, M. M.

    1973-01-01

    Variations of nozzle performance characteristics of the model nozzles used in the Space Shuttle IA12B, IA12C, IA36 power-on launch vehicle test series are shown by comparison between experimental and analytical data. The experimental data are nozzle wall pressure distributions and schlieren photographs of the exhaust plume shapes. The exhaust plume shapes were simulated experimentally with cold flow while the analytical data were generated using a method-of-characteristics solution. Exhaust plume boundaries, boundary shockwave locations and nozzle wall pressure measurements calculated analytically agree favorably with the experimental data from the IA12C and IA36 test series. For the IA12B test series condensation was suspected in the exhaust plumes at the higher pressure ratios required to simulate the prototype plume shapes. Nozzle calibration tests for the series were conducted at pressure ratios where condensation either did not occur or if present did not produce a noticeable effect on the plume shapes. However, at the pressure ratios required in the power-on launch vehicle tests condensation probably occurs and could significantly affect the exhaust plume shapes.

  15. Trends of /sup 13/C//sup 12/C ratios in pinyon tree rings of the American Southwest and the global carbon cycle

    SciTech Connect

    Leavitt, S.W.; Long, A.

    1986-01-01

    An accurate atmospheric /sup 13/C//sup 12/C chronology can provide important constraints to models of the global carbon cycle. Trees accumulate carbon from atmospheric CO/sub 2/ into growth rings and offer potential for /sup 13/C//sup 12/C reconstructions, but results have not been reproducible. This paper presents delta/sup 13/C curves from 5 sites, representing 20 pinyon (Pinus edulis) trees, where cores of 4 trees from each site have been pooled into a composite sample. Isotopic analysis of cellulose in 5-yr ring groups produces curves with a general trend of decreasing delta/sup 13/C after 1800, but with pronounced short-term fluctuations superimposed upon the trend. Evidence indicates the fluctuations are strongly related to moisture availability (drought). A mean curve of the 5 delta/sup 13/C chronologies from which the fossil-fuel component is subtracted suggests a substantial biospheric CO/sub 2/ contribution to the atmosphere since 1800.

  16. Extended analysis of the Ångström band system (B1Σ+ - A1Π) in the rare 12C17O isotopologue

    NASA Astrophysics Data System (ADS)

    Hakalla, R.; Szajna, W.; Zachwieja, M.

    2012-11-01

    The Ångström band system (B1Σ+ - A1Π), so far unobserved in the rare 12C17O isotopologue, was obtained under high resolution as an emission spectrum using high accuracy dispersive optical spectroscopy. In total, 200 transition wave numbers belonging to the 0-1 and 0-2 bands were precisely measured and rotationally analysed. The obtained result was the merged rotational constants B0 = 1.898 8823(41) cm-1 and D0 = 6.4283(26) × 10-6 cm-1 for the B1Σ+ Rydberg state as well as the individual rotational constants B1 = 1.540 88(12) cm-1, D1 = 6.950(87) × 10-6 cm-1, B2 = 1.519 292(69) cm-1, D2 = 8.22(16) × 10-6 cm-1 for the A1Π state in the 12C17O isotopologue. The \\sigma _{0 - v^{\\prime \\prime }} band origins were also calculated. Numerous rotational perturbations observed in the A1Π state in this molecule have been identified. The observed perturbations were confronted with those predicted from theoretical calculations.

  17. Submillimeter Observations of Titan: Global Measures of Stratospheric Temperature, CO, HCN, HC3N, and the Isotopic Ratios 12C/13C and 14N/15N

    NASA Astrophysics Data System (ADS)

    Gurwell, Mark A.

    2004-11-01

    Interferometric observations of the atmosphere of Titan were performed with the Submillimeter Array on two nights in 2004 February to investigate the global average vertical distributions of several molecular species above the tropopause. Rotational transitions of CO, isomers of HCN, and HC3N were simultaneously recorded. The abundance of CO is determined to be 51+/-4 parts per million (ppm), constant with altitude. The vertical profile of HCN is dependent on the assumed temperature but generally increases from 30 parts per billion at the condensation altitude (~83 km) to 5 ppm at ~300 km. Furthermore, the central core of the HCN emission is strong and can be reproduced only if the upper stratospheric temperature increases with altitude. The isotopic ratios are determined to be 12C/13C=132+/-25 and 14N/15N=94+/-13 assuming the Coustenis & Bézard temperature profile. If the Lellouch temperature profile is assumed, the ratios decrease to 12C/13C=108+/-20 and 14N/15N=72+/-9. The vertical profile of HC3N is consistent with that derived by Marten et al.

  18. A large drop in atmospheric [sup 14]C/[sup 12]C and reduced melting in the younger dryas, documented with [sup 230]Th ages of corals

    SciTech Connect

    Edwards, R.L.; Beck, J.W. ); Burr, G.S.; Donahue, D.J. ); Chappell, J.M.A. ); Bloom, A.L. ); Druffel, E.R.M. ); Taylor, F.W. )

    1993-05-14

    Paired carbon-14 ([sup 14]C) and thorium-230 ([sup 230]Th) ages were determined on fossil corals from the Huon Peninsula, Papua New Guinea. The ages were used to calibrate part of the [sup 14]C time scale and to estimate rates of sea-level rise during the last deglaciation. An abrupt offset between the [sup 14]C and [sup 230]Th ages suggests that the atmospheric [sup 14]C/[sup 12]C ratio dropped by 15 percent during the latter part of and after the Younger Dryas (YD). This prominent drop coincides with greatly reduced rates of sea-level rise. Reduction of melting because of cooler conditions during the YD may have caused an increase in the rate of ocean ventilation, which caused the atmospheric [sup 14]C/[sup 12]C ratio to fall. The record of sea-level rise also shows that globally averaged rates of melting were relatively high at the beginning of the YD. Thus, these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the Mississippi to the St. Lawrence River triggered the YD event. 41 refs., 5 figs., 1 tab.

  19. Measurement of the sup 12 C(p,. pi. sup 0 ) sup 13 N sub g. s. reaction using recoil detection

    SciTech Connect

    Homolka, J.; Schott, W.; Wagner, W.; Wilhelm, W. ); Bent, R.D.; Fatyga, M.; Pollock, R.E. ); Saber, M.; Segel, R.E. ); Kienle, P. ); Rehm, K.E. )

    1991-04-10

    Cross sections for the reaction {sup 12}C(p,{pi}{sup 0}){sup 13}N{sub {ital g}.{ital s}.} have been measured at 153.5, 166.1, 186.0 and 204.0 MeV bombarding energy by detection of the {sup 13}N recoil ions. The shapes of the differential cross section angular distributions agree well with those for the {sup 12}C(p,{pi}{sup +}){sup 13}C{sub {ital g}.{ital s}.} reaction obtained by pion detection. The ratio of the (p,{pi}{sup +}) to (p,{pi}{sup 0}) total cross section is close to two, as expected from isospin invariance, at 153.5, 186.0 and 204.0 MeV, but deviates significantly from this at 166.1 MeV bombarding energy. The (p,{pi}{sup +}) and (p,{pi}{sup 0}) cross sections at the lower energies are both larger than expected from an extrapolation of the higher energy data.

  20. Measuring the Fusion Cross-Section of 18O + 12C with Low-Intensity Beams near and below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Steinbach, Tracy; Vadas, Justin; Singh, Varinderjit; Hudan, Sylvie; Desouza, Romualdo; Baby, Lagy; Kuvin, Sean; Wiedenhover, Ingo; Umar, Sait; Oberacker, Volker

    2016-03-01

    Fusion between neutron-rich light nuclei in the crust of an accreting neutron star has been proposed as a heat source that triggers an X-ray superburst. To explore the probability of such fusion events and examine their decay characteristics an experimental program using beams of neutron-rich light nuclei has been initiated. The evaporation residues (ERs) that result from the fusion of 18O and 12C nuclei, are directly measured and distinguished from unreacted beam particles on the basis of their energy and TOF. Using an experimental setup developed for the measurement with low-intensity (<105 ions/s) radioactive beams the fusion excitation function for 18O+12C has been measured in the sub-barrier domain down to the 820 μb level. The measured fusion excitation function is compared to the prediction of a density constrained TDHF model. In addition to the measured cross-section, the measured ER angular distributions provide insight into the relative importance of the different de-excitation channels. These ER angular distributions are compared to the predictions of a statistical model code, EVAPOR revealing an under-prediction of the de-excitation channels associated with α emission. The de-excitation channels associated with proton emission following fusion will also be investigated. Supported by the US DOE under Grant No. DEFG02-88ER-40404.