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Sample records for capture decay rates

  1. Non-Markovian dynamics of quantum systems. II. Decay rate, capture, and pure states

    SciTech Connect

    Palchikov, Yu.V.; Antonenko, N.V.; Kanokov, Z.; Adamian, G.G.; Scheid, W.

    2005-01-01

    On the basis of a master equation for the reduced density matrix of open quantum systems, we study the influence of time-dependent friction and diffusion coefficients on the decay rate from a potential well and the capture probability into a potential well. Taking into account the mixed diffusion coefficient D{sub qp}, the quasistationary decay rates are compared with the analytically derived Kramers-type formulas for different temperatures and frictions. The diffusion coefficients supplying the purity of states are derived for a non-Markovian dynamics.

  2. Measurement of the beta+ and orbital electron-capture decay rates in fully ionized, hydrogenlike, and heliumlike 140Pr ions.

    PubMed

    Litvinov, Yu A; Bosch, F; Geissel, H; Kurcewicz, J; Patyk, Z; Winckler, N; Batist, L; Beckert, K; Boutin, D; Brandau, C; Chen, L; Dimopoulou, C; Fabian, B; Faestermann, T; Fragner, A; Grigorenko, L; Haettner, E; Hess, S; Kienle, P; Knöbel, R; Kozhuharov, C; Litvinov, S A; Maier, L; Mazzocco, M; Montes, F; Münzenberg, G; Musumarra, A; Nociforo, C; Nolden, F; Pfützner, M; Plass, W R; Prochazka, A; Reda, R; Reuschl, R; Scheidenberger, C; Steck, M; Stöhlker, T; Torilov, S; Trassinelli, M; Sun, B; Weick, H; Winkler, M

    2007-12-31

    We report on the first measurement of the beta+ and orbital electron-capture decay rates of 140Pr nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike 140Pr58+ ions is about 50% larger than that of heliumlike 140Pr57+ ions. Moreover, 140Pr ions with one bound electron decay faster than neutral 140Pr0+ atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay. PMID:18233571

  3. Time Modulation of the K-Shell Electron Capture Decay Rates of H-like Heavy Ions at GSI Experiments

    SciTech Connect

    Ivanov, A. N.; Kienle, P.

    2009-08-07

    According to experimental data at GSI, the rates of the number of daughter ions, produced by the nuclear K shell electron capture decays of the H-like heavy ions with one electron in the K shell, such as {sup 140}Pr{sup 58+}, {sup 142}Pm{sup 60+}, and {sup 122}I{sup 52+}, are modulated in time with periods T{sub EC} of the order of a few seconds, obeying an A scaling T{sub EC}=A/20 s, where A is the mass number of the mother nuclei, and with amplitudes a{sub d}{sup EC}approx0.21. We show that these data can be explained in terms of the interference of two massive neutrino mass eigenstates. The appearance of the interference term is due to overlap of massive neutrino mass eigenstate energies and of the wave functions of the daughter ions in two-body decay channels, caused by the energy and momentum uncertainties introduced by time differential detection of the daughter ions in GSI experiments.

  4. Measurement of the {beta}{sup +} and Orbital Electron-Capture Decay Rates in Fully Ionized, Hydrogenlike, and Heliumlike {sup 140}Pr Ions

    SciTech Connect

    Litvinov, Yu. A.; Geissel, H.; Winckler, N.; Knoebel, R.; Litvinov, S. A.; Scheidenberger, C.; Bosch, F.; Beckert, K.; Brandau, C.; Dimopoulou, C.; Hess, S.; Kozhuharov, C.; Mazzocco, M.; Nociforo, C.; Nolden, F.; Prochazka, A.; Reuschl, R.; Steck, M.; Stoehlker, T.; Trassinelli, M.

    2007-12-31

    We report on the first measurement of the {beta}{sup +} and orbital electron-capture decay rates of {sup 140}Pr nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike {sup 140}Pr{sup 58+} ions is about 50% larger than that of heliumlike {sup 140}Pr{sup 57+} ions. Moreover, {sup 140}Pr ions with one bound electron decay faster than neutral {sup 140}Pr{sup 0+} atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay.

  5. Electron-capture and β-decay Rates for sd-Shell Nuclei in Stellar Environments Relevant to High-density O-Ne-Mg Cores

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio; Toki, Hiroshi; Nomoto, Ken'ichi

    2016-02-01

    Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O-Ne-Mg cores of stars with initial masses of 8-10 M⊙. Electron capture induces a rapid contraction of the electron-degenerate O-Ne-Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes are induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O-Ne-Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O-Ne-Mg cores but also a wider range of stars, such as C-O cores of lower-mass stars.

  6. Electron-capture decay rate of {sup 7}Be-C{sub 60} by first-principles calculations based on density functional theory

    SciTech Connect

    Morisato, Tsuguo; Ohno, Kaoru; Ohtsuki, Tsutomu; Hirose, Kentaro; Sluiter, Marcel; Kawazoe, Yoshiyuki

    2008-09-15

    Carrying out a first-principles calculation assuming linear relationship between the electron density at Be nucleus and the electron-capture (EC) decay rate, we explained why {sup 7}Be-C{sub 60} shows higher EC decay rate than {sup 7}Be crystal, which was originally found experimentally by Ohtsuki et al. [Phys. Rev. Lett. 93, 112501 (2004)]. From the results of the calculation, we found that there are inequivalent four stable (i.e., lower energy) Be sites inside C{sub 60} and that center of C{sub 60} (C{sub C60}) is the most favorable site. For C{sub C60}, the electron density at the Be nucleus is the highest. It is also much higher than that at the Be nucleus in a Be crystal. Also, we estimated the expected electron density at the Be nucleus at room temperature by taking statistical average of the electron densities at the four Be nucleus sites using the Boltzmann distribution. The results of the calculation show fairly good agreement with the experimental results. In this paper, we focus on the detail of calculation, which was not fully demonstrated in the paper by Ohtsuki.

  7. Electron capture decay in Jovian planets

    NASA Astrophysics Data System (ADS)

    Zito, R. R.; Schiferl, D.

    1987-12-01

    Following the commonly acknowledged fact that the decay of K-40 substantially contributes to the heating of planetary interiors, an examination is made of the possibility that interior heat in the Jovian planets and stars, where interior pressures may exceed 45 Mbar, may be generated by the pressure-accelerated electron capture decay of a variety of isotopes. The isotopes considered encompass K-40, V-50, Te-123, La-138, Al-26, and Cl-36.

  8. Comment on 'Time modulation of K-shell electron capture decay rates of H-like heavy ions at GSI experiments.'

    SciTech Connect

    Lipkin, H. J.; Physics; Weizmann Inst. of Science; Tel Aviv Univ.

    2010-04-16

    A Comment on the Letter by A.N. Ivanov and P. Kienle, Physical Review Letters volume 103, Issue 6, 062502 (2009). The authors of the Letter offer a Reply to experimental data at GSI, the rates of the number of daughter ions, produced by the nuclear K shell electron capture decays of the H-like heavy ions with one electron in the K shell, such as {sup 140}Pr{sup 58+}, {sup 142}Pm{sup 60+}, and {sup 122}I{sup 52+}, are modulated in time with periods T{sub EC} of the order of a few seconds, obeying an A scaling T{sub EX}=A/20 s, where A is the mass number of the mother nuclei, and with amplitudes a{sub d {sup EC}}{approx}0.21. We show that these data can be explained in terms of the interference of two massive neutrino mass eigenstates. The appearance of the interference term is due to overlap of massive neutrino mass eigenstate energies and of the wave functions of the daughter ions in two-body decay channels, caused by the energy and momentum uncertainties introduced by time differential detection of the daughter ions in GSI experiments.

  9. Decay curve study in a standard electron capture decay

    SciTech Connect

    Nishimura, D.; Fukuda, M.; Kisamori, K.; Kuwada, Y.; Makisaka, K.; Matsumiya, R.; Matsuta, K.; Mihara, M.; Takagi, A.; Yokoyama, R.; Izumikawa, T.; Ohtsubo, T.; Suzuki, T.; Yamaguchi, T.

    2010-05-12

    We have searched for a time-modulated decay in a standard electron capture experiment for {sup 140}Pr, in order to confirm a report from GSI, where an oscillatory decay has been observed for hydrogen-like {sup 140}Pr and {sup 142}Pm ions in the cooler storage ring. {sup 140}Pr has been produced with the {sup 140}Ce(p, n) reaction by a pulsed proton beam accelerated from the Van de Graaff accelerator at Osaka University. Resultant time dependence of the K{sub a}lpha and K{sub b}eta X-ray intensities from the daughter shows no oscillatory behavior.

  10. Some options for the muon collider capture and decay solenoids

    NASA Astrophysics Data System (ADS)

    Green, Michael A.

    1996-05-01

    This report discusses some of the problems associated with using solenoid magnets to capture the secondary particles that are created when an intense beam of 8 to 10 GeV protons interacts with the target at the center of the capture region. Hybrid capture solenoids with inductions of 28 T and a 22 T are described. The first 14 to 15 T of the solenoid induction will be generated by a superconducting magnet. The remainder of the field will be generated by a Bitter type of water cooled solenoid. The capture solenoids include a transition section from the high field solenoid to a 7 T decay channel where pions and kaons that come off of the target decay into muons. A short 7 T solenoidal decay channel between the capture solenoid system and the phase rotation system is described. A concept for separation of negative and positive pions and kaons is briefly discussed.

  11. Neutron Capture Rates and r-PROCESS Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Surman, R. A.; Mumpower, M. R.; McLaughlin, G. C.; Sinclair, R.; Hix, W. R.; Jones, K. L.

    2013-03-01

    Simulations of r-process nucleosynthesis require nuclear physics information for thousands of neutron-rich nuclear species from the line of stability to the neutron drip line. While arguably the most important pieces of nuclear data for the r-process are the masses and β decay rates, individual neutron capture rates can also be of key importance in setting the final r-process abundance pattern. Here we consider the influence of neutron capture rates in forming the A ~ 80 and rare earth peaks.

  12. The calorimetric spectrum of the electron-capture decay of 163Ho. The spectral endpoint region

    NASA Astrophysics Data System (ADS)

    De Rújula, A.; Lusignoli, M.

    2016-05-01

    The electron-neutrino mass (or masses and mixing angles) may be directly measurable in weak electron-capture decays. The favoured experimental technique is "calorimetric". The optimal nuclide is 163Ho, and several experiments (ECHo, HOLMES and NuMECS) are currently studying its decay. The most relevant range of the calorimetric-energy spectrum extends for the last few hundred eV below its endpoint. It has not yet been well measured. We explore the theory, mainly in the cited range, of electron capture in 163Ho decay. A so far neglected process turns out to be most relevant: electron-capture accompanied by the shake-off of a second electron. Our two main conclusions are very encouraging: the counting rate close to the endpoint may be more than an order of magnitude larger than previously expected; the "pile-up" problem may be significantly reduced.

  13. Radiative Electron Capture in the First-Forbidden Unique Decay of 81Kr

    SciTech Connect

    Mianowski, S.; Werner-Malento, E.; Korgul, A.; Pomorski, M.; Pachucki, K.; Pfutzner, M.; Szweryn, B.; Zylicz, J.; Hornshoj, P.; Nilsson, T.; Rykaczewski, Krzysztof Piotr

    2010-01-01

    The photon spectrum accompanying the orbital K-electron capture in the first-forbidden unique decay of 81Kr was measured.The total radiation intensity for photon energies larger than 50 keVwas found to be 1.42(22) 10 4 per K capture. Both the shape of the spectrum and its intensity relative to the ordinary, nonradiative capture rate are compared to theoretical predictions. The best agreement is found for the recently developed model that employs the length gauge for the electromagnetic field.

  14. Searching for Experimental Verification of the Oscillation of Electron Capture Decay Probability

    NASA Astrophysics Data System (ADS)

    Vetter, Paul

    2009-05-01

    A group from Gesellschaft f"ur Schwerionenforschung (GSI) last year published an observation of time oscillations of the electron capture decay rate of stored hydrogen-like ions of ^142Pm and ^140Pr.(Phys. Lett. B 664, 162 (2008)). They proposed that the oscillating decay rate was caused by interference between momentum states of the ion caused by neutrino mass and flavor mixing. This hypothesis has been controversial, with several authors arguing either that neutrino mixing can or cannot be responsible. If neutrino mixing is responsible for the decay rate oscillations, then it should be possible to detect these oscillations in a simpler experiment without using stored hydrogenic ions, by observing an electron capture decay rate with an appropriate experiment time structure. If this were possible, it could revolutionize the study of neutrino mixing by allowing much simpler experiments to make precise measurements of mass differences and mixing angles. At LBNL, we performed an experiment to search for oscillations in electron capture rate using ^142Pm produced with a time short compared to the oscillation period, and counting ^142Nd Kα x-rays from the daughter. The decay time spectrum is well-described by a simple exponential, and we observed no statistically significant decay rate oscillations at a level much lower than proposed. A literature search for previous experiments that might have been sensitive to the reported modulation uncovered a candidate in ^142Eu. A reanalysis of that published data shows no decay rate oscillation. A recent experiment at Munich also did not observe decay rate oscillations in decays of ^180Re. Other potential explanations for the GSI decay oscillation data have been proposed, including quantum beats by nearly degenerate initial parent ion states and Thomas precession in the stored ions. I will discuss the status of experimental results, and possibilities for experimental confirmation of the various models. This work was supported by

  15. Accurate Q-Value for the ^{74}Se Double Electron Capture Decay

    SciTech Connect

    Kolhinen, V. S.; Elomaa, V.-V.; Eronen, T.; Hakala, J.; Jokinen, A.; Kortelainen, M.; Suhonen, J.; Aysto, J.

    2010-01-01

    The Q value of the neutrinoless double electron capture (0{nu}ECEC) decay of ^{74}Se was measured by using the JYFLTRAP Penning trap. The determined value is 1209.169(49) keV, which practically excludes the possibility of a complete energy degeneracy with the second 2^{+} state (1204-205(7) keV) of ^{74}Ge in a resoant 0{nu}ECEC decay. We have also computed the associated nuclear matrix element by using a microscopic nuclear model with realistic two-nucleon interactions. The computed matrix element is found to be quite small. The failure of the resonant condition, combined with the small nuclear matrix element and needed p-wave capture, suppresses the decay rate strongly and thus excludes ^{74}Se as a possible candidate to search for resonant 0{nu}ECEC processes.

  16. Ratios of heavy hadron semileptonic decay rates

    SciTech Connect

    Gronau, Michael; Rosner, Jonathan L.

    2011-02-01

    Ratios of charmed meson and baryon semileptonic decay rates appear to be satisfactorily described by considering only the lowest-lying (S-wave) hadronic final states and assuming the kinematic factor describing phase space suppression is the same as that for free quarks. For example, the rate for D{sub s} semileptonic decay is known to be (17.0{+-}5.3)% lower than those for D{sup 0} or D{sup +}, and the model accounts for this difference. When applied to hadrons containing b quarks, this method implies that the B{sub s} semileptonic decay rate is about 1% higher than that of the nonstrange B mesons. This small difference thus suggests surprisingly good local quark-hadron duality for B semileptonic decays, complementing the expectation based on inclusive quark-hadron duality that these differences in rates should not exceed a few tenths of a percent. For {Lambda}{sub b} semileptonic decay, however, the inclusive rate is predicted to be about 13% greater than that of the nonstrange B mesons. This value, representing a considerable departure from a calculation using a heavy-quark expansion, is close to the corresponding experimental ratio {Gamma}({Lambda}{sub b})/{Gamma}(B)=1.13{+-}0.03 of total decay rates.

  17. Systematic muon capture rates in PQRPA

    SciTech Connect

    Samana, A. R.; Sande, D.; Krmpotić, F.

    2015-05-15

    In this work we performed a systematic study of the inclusive muon capture rates for several nuclei with A < 60 using the Projected Random Quasi-particle Phase Approximation (PQRPA) as nuclear model, because it is the only RPA model that treats the Pauli Principle correctly. We reckon that the comparison between theory and data for the inclusive muon capture is not a fully satisfactory test on the nuclear model that is used. The exclusive muon transitions are more robust for such a purpose.

  18. Power spectrum analyses of nuclear decay rates

    NASA Astrophysics Data System (ADS)

    Javorsek, D.; Sturrock, P. A.; Lasenby, R. N.; Lasenby, A. N.; Buncher, J. B.; Fischbach, E.; Gruenwald, J. T.; Hoft, A. W.; Horan, T. J.; Jenkins, J. H.; Kerford, J. L.; Lee, R. H.; Longman, A.; Mattes, J. J.; Morreale, B. L.; Morris, D. B.; Mudry, R. N.; Newport, J. R.; O'Keefe, D.; Petrelli, M. A.; Silver, M. A.; Stewart, C. A.; Terry, B.

    2010-10-01

    We provide the results from a spectral analysis of nuclear decay data displaying annually varying periodic fluctuations. The analyzed data were obtained from three distinct data sets: 32Si and 36Cl decays reported by an experiment performed at the Brookhaven National Laboratory (BNL), 56Mn decay reported by the Children's Nutrition Research Center (CNRC), but also performed at BNL, and 226Ra decay reported by an experiment performed at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. All three data sets exhibit the same primary frequency mode consisting of an annual period. Additional spectral comparisons of the data to local ambient temperature, atmospheric pressure, relative humidity, Earth-Sun distance, and their reciprocals were performed. No common phases were found between the factors investigated and those exhibited by the nuclear decay data. This suggests that either a combination of factors was responsible, or that, if it was a single factor, its effects on the decay rate experiments are not a direct synchronous modulation. We conclude that the annual periodicity in these data sets is a real effect, but that further study involving additional carefully controlled experiments will be needed to establish its origin.

  19. Halley's comet - Its size and decay rate

    NASA Astrophysics Data System (ADS)

    Wallis, M. K.; Wickramasinghe, N. C.

    1985-09-01

    The outgassing rates inferred from the 1910 apparition and the brightness decay over the previous two millenia are compatible with the minimum nuclear brightness currently observed if the comet nucleus is small, 1.8 - 2.7 km radius with an albedo of 0.1 - 0.2. Outgassing is faster than from a bare nucleus of dirty H2O-ice, which is attributed either to a hot microdust coma or to an organic polymer composition. Halley's comet will decay away within another 45 - 65 apparitions.

  20. Observation of Energy-Dependent Electron-Capture Decay in Secondary Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Niebur, S. M.; Binns, W. R.; Hink, P. L.; Israel, M. H.; Klarmann, J.; Lijowski, M.; Christian, E. R.; von Rosenvinge, T. T.; Cummings, A. C.; George, J. S.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; Wiedenbeck, M. E.; Yanasak, N. E.

    2000-04-01

    Secondary galactic cosmic rays are produced at cosmic ray energies by fragmentation of primary cosmic rays during propagation through the interstellar medium; these nuclei carry a signature of the energy at which they were produced. Although electron-capture decay is inhibited at most of the energies typical of cosmic rays, decay is possible at the lower energies for isotopes such as 51Cr and 49V. We have analyzed Titanium, Vanadium, and Chromium isotopic data from the Cosmic Ray Isotope Spectrometer on ACE and found evidence of electron-capture decay at lower energies. We will present a comparison of secondary electron-capture decay isotope abundances and abundances of their decay products with results from improved propagation models in order to discuss the amount of electron-capture decay and subsequent acceleration that may have occurred during propagation.

  1. MAGNETIC FIELD-DECAY-INDUCED ELECTRON CAPTURES: A STRONG HEAT SOURCE IN MAGNETAR CRUSTS

    SciTech Connect

    Cooper, Randall L.; Kaplan, David L. E-mail: dkaplan@kitp.ucsb.edu

    2010-01-10

    We propose a new heating mechanism in magnetar crusts. Magnetars' crustal magnetic fields are much stronger than their surface fields; therefore, magnetic pressure partially supports the crust against gravity. The crust loses magnetic pressure support as the field decays and must compensate by increasing the electron degeneracy pressure; the accompanying increase in the electron Fermi energy induces nonequilibrium, exothermic electron captures. The total heat released via field-decay electron captures is comparable to the total magnetic energy in the crust. Thus, field-decay electron captures are an important, if not the primary, mechanism powering magnetars' soft X-ray emission.

  2. Calculation of doublet capture rate for muon capture in deuterium within chiral effective field theory

    NASA Astrophysics Data System (ADS)

    Adam, J.; Tater, M.; Truhlík, E.; Epelbaum, E.; Machleidt, R.; Ricci, P.

    2012-03-01

    The doublet capture rate Λ1 / 2 of the negative muon capture in deuterium is calculated employing the nuclear wave functions generated from accurate nucleon-nucleon (NN) potentials constructed at next-to-next-to-next-to-leading order of heavy-baryon chiral perturbation theory and the weak meson exchange current operator derived within the same formalism. All but one of the low-energy constants that enter the calculation were fixed from pion-nucleon and nucleon-nucleon scattering data. The low-energy constant dˆR (cD), which cannot be determined from the purely two-nucleon data, was extracted recently from the triton β-decay and the binding energies of the three-nucleon systems. The calculated values of Λ1 / 2 show a rather large spread for the used values of the dˆR. Precise measurement of Λ1 / 2 in the future will not only help to constrain the value of dˆR, but also provide a highly nontrivial test of the nuclear chiral EFT framework. Besides, the precise knowledge of the constant dˆR will allow for consistent calculations of other two-nucleon weak processes, such as proton-proton fusion and solar neutrino scattering on deuterons, which are important for astrophysics.

  3. Universal Distribution of Litter Decay Rates

    NASA Astrophysics Data System (ADS)

    Forney, D. C.; Rothman, D. H.

    2008-12-01

    Degradation of litter is the result of many physical, chemical and biological processes. The high variability of these processes likely accounts for the progressive slowdown of decay with litter age. This age dependence is commonly thought to result from the superposition of processes with different decay rates k. Here we assume an underlying continuous yet unknown distribution p(k) of decay rates [1]. To seek its form, we analyze the mass-time history of 70 LIDET [2] litter data sets obtained under widely varying conditions. We construct a regularized inversion procedure to find the best fitting distribution p(k) with the least degrees of freedom. We find that the resulting p(k) is universally consistent with a lognormal distribution, i.e.~a Gaussian distribution of log k, characterized by a dataset-dependent mean and variance of log k. This result is supported by a recurring observation that microbial populations on leaves are log-normally distributed [3]. Simple biological processes cause the frequent appearance of the log-normal distribution in ecology [4]. Environmental factors, such as soil nitrate, soil aggregate size, soil hydraulic conductivity, total soil nitrogen, soil denitrification, soil respiration have been all observed to be log-normally distributed [5]. Litter degradation rates depend on many coupled, multiplicative factors, which provides a fundamental basis for the lognormal distribution. Using this insight, we systematically estimated the mean and variance of log k for 512 data sets from the LIDET study. We find the mean strongly correlates with temperature and precipitation, while the variance appears to be uncorrelated with main environmental factors and is thus likely more correlated with chemical composition and/or ecology. Results indicate the possibility that the distribution in rates reflects, at least in part, the distribution of microbial niches. [1] B. P. Boudreau, B.~R. Ruddick, American Journal of Science,291, 507, (1991). [2] M

  4. Molecular decay rate near nonlocal plasmonic particles.

    PubMed

    Girard, Christian; Cuche, Aurélien; Dujardin, Erik; Arbouet, Arnaud; Mlayah, Adnen

    2015-05-01

    When the size of metal nanoparticles is smaller than typically 10 nm, their optical response becomes sensitive to both spatial dispersion and quantum size effects associated with the confinement of the conduction electrons inside the particle. In this Letter, we propose a nonlocal scheme to compute molecular decay rates near spherical nanoparticles which includes the electron-electron interactions through a simple model of electronic polarizabilities. The plasmonic particle is schematized by a dynamic dipolar polarizability α(NL)(ω), and the quantum system is characterized by a two-level system. In this scheme, the light matter interaction is described in terms of classical field susceptibilities. This theoretical framework could be extended to address the influence of nonlocality on the dynamics of quantum systems placed in the vicinity of nano-objects of arbitrary morphologies. PMID:25927799

  5. Aftershock Decay Rates in the Iranian Plateau

    NASA Astrophysics Data System (ADS)

    Ommi, S.; Zafarani, H.; Zare, M.

    2016-04-01

    Motivated by the desire to have more information following the occurrence of damaging events, the main purpose of this article is to study aftershock sequence parameters in the Iranian plateau. To this end, the catalogue of the Iranian earthquakes between 2002 to the end of 2013 has been collected and homogenized among which 15 earthquakes have been selected to study their aftershock decay rates. For different tectonic provinces, the completeness magnitudes (M c) of the earthquake catalogue have been calculated in different time intervals. Also, the M c variability in spatial and temporal windows has been determined for each selected event. For major Iranian earthquakes, catalogue of aftershocks has been collected thanks to three declustering methods: first, the classical windowing method of uc(Gardner) and uc(Knopoff) (Bull Seismol Soc Am 64:1363-1367, 1974); second, a modified version of this using spatial windowing based on the uc(Wells) and uc(Coppersmith) (Bull Seismol Soc Am 84:974-1002, 1994) relations; and third, the uc(Burkhard) and uc(Grünthal) (Swiss J Geosci 102:149-188, 2009) scheme. Effects of the temporal windows also have been investigated using the time periods of 1 month, 100 days, and 1 year in the declustering method of uc(Gardner) and uc(Knopoff) (Bull Seismol Soc Am 64:1363-1367, 1974). In the next step, the modified Omori law coefficients have been calculated for the 15 selected earthquakes. The calibrated regional generic model describing the temporal and magnitude distribution of aftershocks is of interest for time-dependent seismic hazard forecasts. The regional characteristics of the aftershock decay rates have been studied for the selected Iranian earthquakes in the Alborz, Zagros and Central Iran regions considering their different seismotectonics regimes. However, due to the lack of sufficient data, no results have been reported for the Kopeh-Dagh and Makran seismotectonic regions.

  6. Aftershock Decay Rates in the Iranian Plateau

    NASA Astrophysics Data System (ADS)

    Ommi, S.; Zafarani, H.; Zare, M.

    2016-07-01

    Motivated by the desire to have more information following the occurrence of damaging events, the main purpose of this article is to study aftershock sequence parameters in the Iranian plateau. To this end, the catalogue of the Iranian earthquakes between 2002 to the end of 2013 has been collected and homogenized among which 15 earthquakes have been selected to study their aftershock decay rates. For different tectonic provinces, the completeness magnitudes ( M c) of the earthquake catalogue have been calculated in different time intervals. Also, the M c variability in spatial and temporal windows has been determined for each selected event. For major Iranian earthquakes, catalogue of aftershocks has been collected thanks to three declustering methods: first, the classical windowing method of Gardner and Knopoff (Bull Seismol Soc Am 64:1363-1367, 1974); second, a modified version of this using spatial windowing based on the Wells and Coppersmith (Bull Seismol Soc Am 84:974-1002, 1994) relations; and third, the Burkhard and Grünthal (Swiss J Geosci 102:149-188, 2009) scheme. Effects of the temporal windows also have been investigated using the time periods of 1 month, 100 days, and 1 year in the declustering method of Gardner and Knopoff (Bull Seismol Soc Am 64:1363-1367, 1974). In the next step, the modified Omori law coefficients have been calculated for the 15 selected earthquakes. The calibrated regional generic model describing the temporal and magnitude distribution of aftershocks is of interest for time-dependent seismic hazard forecasts. The regional characteristics of the aftershock decay rates have been studied for the selected Iranian earthquakes in the Alborz, Zagros and Central Iran regions considering their different seismotectonics regimes. However, due to the lack of sufficient data, no results have been reported for the Kopeh-Dagh and Makran seismotectonic regions.

  7. Captures of hot and warm sterile antineutrino dark matter on EC-decaying {sup 63}Ho nuclei

    SciTech Connect

    Li, Y.F.; Xing, Zhi-zhong E-mail: xingzz@ihep.ac.cn

    2011-08-01

    Capturing low-energy electron antineutrinos on radioactive {sup 163}Ho nuclei, which decay into {sup 163}Dy via electron capture (EC), is a noteworthy opportunity to detect relic sterile antineutrinos. Such hypothetical particles are more or less implied by current experimental and cosmological data, and they might be a part of hot dark matter or a candidate for warm dark matter in the Universe. Using the isotope {sup 163}Ho as a target and assuming reasonable active-sterile antineutrino mixing angles, we calculate the capture rate of relic electron antineutrinos against the corresponding EC-decay background in the presence of sterile antineutrinos at the sub-eV or keV mass scale. We show that the signature of hot or warm sterile antineutrino dark matter should in principle be observable, provided the target is big enough and the energy resolution is good enough.

  8. Capturing the rare decay kaon+ to pion+ neutrino antineutrino

    NASA Astrophysics Data System (ADS)

    Stone, Jesse R.

    This thesis describes a search for the rare decay K+-->p+noverlinenoverline , a Flavor Changing Neutral Current (FCNC) process forbidden to first order in the Standard Model by the GIM mechanism. The decay is allowed at second order, however, and expected to have a branching ratio of approximately 10-10. Thanks to the presence of an internal top quark in the diagrams for this process, a measurement of the branching ratio for K+-->p+noverlinenoverline provides a measurement of the Cabibbo- Kobayashi-Maskawa matrix element Vtd. Data collected by Experiment 787 at Brookhaven National Laboratory during the 1995 run were analyzed, and one candidate event surfaced with an expected background of 0.08 +/- 0.03 events. This first observation of K+-->p+noverlinenoverline yields a branching ratio of BR( K+-->p+noverlinenoverline ) = ( (2.54+5.82- 2.10 )×10-10 . A simultaneous search for the decay K+-->p+X0 , where X0 is any massless, weakly interacting particle, yielded no candidate events, and a 90% confidence level upper limit on the branching ratio is set at 1.81×10-10.

  9. Weak {gamma}-transition intensities in the electron capture decay of {sup 144}Pm

    SciTech Connect

    Robinson, S.J.; Altgilbers, A.S.; Hindi, M.M.; Norman, E.B.; Larimer, R.

    1996-09-01

    We have determined the absolute intensity of weak {gamma} transitions in the level scheme of {sup 144}Nd, observed following the electron capture decay of {sup 144}Pm. The absolute intensity of the 1397-keV {ital E}3 branch from the 2093-keV (5{sub 1}{sup {minus}}) level was determined to be (4.9 {plus_minus} 0.7) {times} 10{sup {minus}4}{percent}. This leads to a revised absolute transition rate of {ital B}({ital E}3;5{sub 1}{sup {minus}}{r_arrow}2{sup +}{sub 1})=26{sub {minus}12}{sup +15} Weisskopf units, which is still consistent with an interpretation of the 5{sub 1}{sup {minus}} level based on quadrupole-octupole coupling. {copyright} {ital 1996 The American Physical Society.}

  10. Asynchronous beating of cilia enhances particle capture rate

    NASA Astrophysics Data System (ADS)

    Ding, Yang; Kanso, Eva

    2014-11-01

    Many aquatic micro-organisms use beating cilia to generate feeding currents and capture particles in surrounding fluids. One of the capture strategies is to ``catch up'' with particles when a cilium is beating towards the overall flow direction (effective stroke) and intercept particles on the downstream side of the cilium. Here, we developed a 3D computational model of a cilia band with prescribed motion in a viscous fluid and calculated the trajectories of the particles with different sizes in the fluid. We found an optimal particle diameter that maximizes the capture rate. The flow field and particle motion indicate that the low capture rate of smaller particles is due to the laminar flow in the neighbor of the cilia, whereas larger particles have to move above the cilia tips to get advected downstream which decreases their capture rate. We then analyzed the effect of beating coordination between neighboring cilia on the capture rate. Interestingly, we found that asynchrony of the beating of the cilia can enhance the relative motion between a cilium and the particles near it and hence increase the capture rate.

  11. Sensitivity studies for the main r process: β-decay rates

    SciTech Connect

    Mumpower, M.; Cass, J.; Passucci, G.; Aprahamian, A.; Surman, R.

    2014-04-15

    The pattern of isotopic abundances produced in rapid neutron capture, or r-process, nucleosynthesis is sensitive to the nuclear physics properties of thousands of unstable neutron-rich nuclear species that participate in the process. It has long been recognized that the some of the most influential pieces of nuclear data for r-process simulations are β-decay lifetimes. In light of experimental advances that have pushed measurement capabilities closer to the classic r-process path, we revisit the role of individual β-decay rates in the r process. We perform β-decay rate sensitivity studies for a main (A > 120) r process in a range of potential astrophysical scenarios. We study the influence of individual rates during (n, γ)-(γ, n) equilibrium and during the post-equilibrium phase where material moves back toward stability. We confirm the widely accepted view that the most important lifetimes are those of nuclei along the r-process path for each astrophysical scenario considered. However, we find in addition that individual β-decay rates continue to shape the final abundance pattern through the post-equilibrium phase, for as long as neutron capture competes with β decay. Many of the lifetimes important for this phase of the r process are within current or near future experimental reach.

  12. Sensitivity studies for the weak r process: neutron capture rates

    SciTech Connect

    Surman, R.; Mumpower, M.; Sinclair, R.; Jones, K. L.; Hix, W. R.; McLaughlin, G. C.

    2014-04-15

    Rapid neutron capture nucleosynthesis involves thousands of nuclear species far from stability, whose nuclear properties need to be understood in order to accurately predict nucleosynthetic outcomes. Recently sensitivity studies have provided a deeper understanding of how the r process proceeds and have identified pieces of nuclear data of interest for further experimental or theoretical study. A key result of these studies has been to point out the importance of individual neutron capture rates in setting the final r-process abundance pattern for a ‘main’ (A ∼ 130 peak and above) r process. Here we examine neutron capture in the context of a ‘weak’ r process that forms primarily the A ∼ 80 r-process abundance peak. We identify the astrophysical conditions required to produce this peak region through weak r-processing and point out the neutron capture rates that most strongly influence the final abundance pattern.

  13. Experimental Neutron Capture Rate Constraint Far from Stability.

    PubMed

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

    2016-06-17

    Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on ^{69}Ni, a nucleus that is five neutrons away from the last stable isotope of Ni. The implications of this measurement on nucleosynthesis around mass 70 are discussed, and the impact of similar future measurements on the understanding of the origin of the heavy elements in the cosmos is presented. PMID:27367386

  14. Experimental Neutron Capture Rate Constraint Far from Stability

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  15. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  16. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  17. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  18. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  19. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  20. Modern Measurements of Uranium Decay Rates

    NASA Astrophysics Data System (ADS)

    Parsons-Moss, T.; Faye, S. A.; Williams, R. W.; Wang, T. F.; Renne, P. R.; Mundil, R.; Harrison, M.; Bandong, B. B.; Moody, K.; Knight, K. B.

    2015-12-01

    It has been widely recognized that accurate and precise decay constants (λ) are critical to geochronology as highlighted by the EARTHTIME initiative, particularly the calibration benchmarks λ235U and λ238U. [1] Alpha counting experiments in 1971[2] measured λ235U and λ238U with ~0.1% precision, but have never been independently validated. We are embarking on new direct measurements of λ235U, λ238U, λ234Th, and λ234U using independent approaches for each nuclide. For the measurement of λ235U, highly enriched 235U samples will be chemically purified and analyzed for U concentration and isotopic composition by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Thin films will be electrodeposited from these solutions and the α activity will be measured in an α-γ coincidence counting apparatus, which allows reduced uncertainty in counting efficiency while achieving adequate counting statistics. For λ238U measurement we will measure ingrowth of 234Th in chemically purified, isotopically enriched 238U solutions, by quantitatively separating the Th and allowing complete decay to 234U. All of the measurements will be done using MC-ICP-MS aiming at 0.05% precision. This approach is expected to result in values of λ238U with less than 0.1% uncertainty, if combined with improved λ234Th measements. These will be achieved using direct decay measurements with an E-∆E charged particle telescope in coincidence with a gamma detector. This system allows measurement of 234Th β-decay and simultaneous detection and identification of α particles emitted by the 234U daughter, thus observing λ234U at the same time. The high-precision λ234U obtained by the direct activity measurements can independently verify the commonly used values obtained by indirect methods.[3] An overarching goal of the project is to ensure the quality of results including metrological traceability in order to facilitate implementation across diverse disciplines. [1] T

  1. Stellar capture rates for s-process strong component elements.

    NASA Astrophysics Data System (ADS)

    Mutti, P.; Corvi, F.; Athanassopoulos, K.; Beer, H.; Krupchitsky, P.

    The strong component of the s-process is required for the synthesis of the heaviest s-process elements, namely the lead and the bismuth isotopes. The termination of the path occurs via a cyclic process in which nuclei heavier than bismuth decay via alpha emission to isotopes of lead. In this mass region the abundances are strongly influenced by the double magic 208Pb which, having the smallest cross section of all the heavy elements, acts as a bottle-neck in the s-process path. In the framework of a thorough investigation in the atomic mass region around the neutron magic nuclei, the 209Bi and 207Pb capture cross sections were measured with high resolution at the Geel electron linear accelerator. Capture areas were determined for neutron resonances in a wide energy range and the Maxwellian-averaged cross sections were derived as a function of stellar temperature.

  2. Rate of gravitational inflaton decay via gauge trace anomaly

    SciTech Connect

    Watanabe, Yuki

    2011-02-15

    We analyze decay processes of the inflaton field, {phi}, during the coherent oscillation phase after inflation in f({phi})R gravity. It is inevitable that the inflaton decays gravitationally into gauge fields in the presence of f({phi})R coupling. We show a concrete calculation of the rate that the inflaton field decays into a pair of gauge fields via the trace anomaly. Comparing this new decay channel via the anomaly with the channels from the tree-level analysis, we find that the branching ratio crucially depends on masses and the internal multiplicities (flavor quantum number) of decay product particles. While the inflaton decays exclusively into light fields, heavy fields still play a role in quantum loops. We argue that this process in principle allows us to constrain the effects of arbitrary heavy particles in the reheating. We also apply our analysis to Higgs inflation, and find that the gravitational decay rate would never exceed gauge interaction decay rates if quantum gravity is unimportant.

  3. The decay rates of autoionizing quasi-molecular states

    NASA Astrophysics Data System (ADS)

    Kishinevsky, L. M.; Krakov, B. G.; Parilis, E. S.

    1981-09-01

    The decay rates of three quasi-molecular autoionizing states of a HeBe 4+-like system consisting of two electrons and two Coulomb centres are calculated. It is shown that with decreasing internuclear distance the decay rate passes through a maximum which for (2 pσ) 2 states is 1.6 × 10 15s-1. This considerably exceeds the value for the united atom.

  4. Auger Stimulated Ion Desorption of Negative Ions via K -Capture Radioactive Decay

    SciTech Connect

    Verkhoturov, S. V.; Schweikert, E. A.; Chechik, Victor; Sabapathy, Rajaram C.; Crooks, Richard M.; Parilis, E. S.

    2001-07-16

    We report on Auger stimulated ion desorption via Coulomb explosion from surface self-assembled alkylthiol and fluorocarbon molecular layers, triggered by K -capture decay of an imbedded radioactive {sup 55}Fe atom. The charge state of the ejecta is determined by charge exchange in binary atomic collisions in bulk and electron tunneling outside the solid, as well as by fragmentation of electronically excited molecules or molecular fragments. We describe the first nonbeam experiments documenting positive and abundant negative ion desorption due solely to core electron excitation after radioactive decay.

  5. Decay rate of the second radiation belt

    NASA Astrophysics Data System (ADS)

    Badhwar, G. D.; Robbins, D. E.

    Variations in the Earth's trapped (Van Allen) belts produced by solar flare particle events are not well understood. Few observations of increases in particle populations have been reported. This is particularly true for effects in low Earth orbit, where manned spaceflights are conducted. This paper reports the existence of a second proton belt and it's subsequent decay as measured by a tissue-equivalent proportional counter and a particle spectrometer on five Space Shuttle flights covering an eighteen-month period. The creation of this second belt is attributed to the injection of particles from a solar particle event which occurred at 2246 UT, March 22, 1991. Comparisons with observations onboard the Russian Mir space station and other unmanned satellites are made. Shuttle measurements and data from other spacecraft are used to determine that the e-folding time of the peak of the second proton belt. It was ten months. Proton populations in the second belt returned to values of quiescent times within eighteen months. The increase in absorbed dose attributed to protons in the second belt was approximately 20%. Passive dosimeter measurements were in good agreement with this value.

  6. A comparison of radiative capture with decay gamma-ray method in bore hole logging for economic minerals

    USGS Publications Warehouse

    Senftle, F.E.; Moxham, R.M.; Tanner, A.B.

    1972-01-01

    The recent availability of borehole logging sondes employing a source of neutrons and a Ge(Li) detector opens up the possibility of analyzing either decay or capture gamma rays. The most efficient method for a given element can be predicted by calculating the decay-to-capture count ratio for the most prominent peaks in the respective spectra. From a practical point of view such a calculation must be slanted toward short irradiation and count times at each station in a borehole. A simplified method of computation is shown, and the decay-to-capture count ratio has been calculated and tabulated for the optimum value in the decay mode irrespective of the irradiation time, and also for a ten minute irradiation time. Based on analysis of a single peak in each spectrum, the results indicate the preferred technique and the best decay or capture peak to observe for those elements of economic interest. ?? 1972.

  7. Possible capture of keV sterile neutrino dark matter on radioactive β-decaying nuclei

    NASA Astrophysics Data System (ADS)

    Li, Y. F.; Xing, Zhi-Zhong

    2011-01-01

    There exists an observed “desert” spanning six orders of magnitude between O(0.5) eV and O(0.5) MeV in the fermion mass spectrum. We argue that it might accommodate one or more keV sterile neutrinos as a natural candidate for warm dark matter. To illustrate this point of view, we simply assume that there is one keV sterile neutrino ν and its flavor eigenstate ν weakly mixes with three active neutrinos. We clarify different active-sterile neutrino mixing factors for the radiative decay of ν and β decays in a self-consistent parametrization. A direct detection of this keV sterile neutrino dark matter in the laboratory is in principle possible since the ν component of ν can leave a distinct imprint on the electron energy spectrum when it is captured on radioactive β-decaying nuclei. We carry out an analysis of its signatures in the capture reactions ν+H3→He3+e- and ν+Ru106→Rh106+e- against the β-decay backgrounds, and conclude that this experimental approach might not be hopeless in the long run.

  8. Measuring the Rate of Muon Capture on the Deuteron

    NASA Astrophysics Data System (ADS)

    Ibanez, Luis

    2014-03-01

    The goal of the MuSun experiment is to measure the rate of nuclear muon capture on the deuteron with a precision of 1.5%. This rate will be used to fix the low-energy constant that describes the two-nucleon weak axial current in effective field theory models. It will therefore calibrate evaluations of proton-proton fusion and neutrino-deuteron scattering. The experiment uses many of the techniques and much of the apparatus that were developed for the successful MuCap measurement of the rate of muon capture on the proton. However, to optimize the molecular kinetics, the deuterium gas is cooled to 30 K in a cryogenic time projection chamber (TPC). Progress in the analysis of the data taken during the production run of 2011 will be presented, as well as a description of the hardware upgrades and performance during the 2013 run, in preparation for another high-statistics run in 2014.

  9. Photoluminescence decay rate of silicon nanoparticles modified with gold nanoislands

    PubMed Central

    2014-01-01

    We investigated plasmon-assisted enhancement of emission from silicon nanoparticles (ncs-Si) embedded into porous SiO x matrix in the 500- to 820-nm wavelength range. In the presence in the near-surface region of gold nanoisland film, ncs-Si exhibited up to twofold luminescence enhancement at emission frequencies that correspond to the plasmon resonance frequency of Au nanoparticles. Enhancement of the photoluminescence (PL) intensity was attributed to coupling with the localized surface plasmons (LSPs) excited in Au nanoparticles and to increase in the radiative decay rate of ncs-Si. It has been shown that spontaneous emission decay rate of ncs-Si modified by thin Au film over the wide emission spectral range was accelerated. The emission decay rate distribution was determined by fitting the experimental decay curves to the stretched exponential model. The observed increase of the PL decay rate distribution width for the Au-coated nc-Si-SiO x sample in comparison with the uncoated one was explained by fluctuations in the surface-plasmon excitation rate. PACS 78. 67. Bf; 78.55.-m PMID:24708532

  10. Energy decay rate of the thermoelastic Bresse system

    NASA Astrophysics Data System (ADS)

    Liu, Zhuangyi; Rao, Bopeng

    2009-01-01

    In this paper, we study the energy decay rate for the thermoelastic Bresse system which describes the motion of a linear planar, shearable thermoelastic beam. If the longitudinal motion and heat transfer are neglected, this model reduces to the well-known thermoelastic Timoshenko beam equations. The system consists of three wave equations and two heat equations coupled in certain pattern. The two wave equations about the longitudinal displacement and shear angle displacement are effectively damped by the dissipation from the two heat equations. Actually, the corresponding energy decays exponentially like the classical one-dimensional thermoelastic system. However, the third wave equation about the vertical displacement is only weakly damped. Thus the decay rate of the energy of the overall system is still unknown. We will show that the exponentially decay rate is preserved when the wave speed of the vertical displacement coincides with the wave speed of longitudinal displacement or of the shear angle displacement. Otherwise, only a polynomial type decay rate can be obtained. These results are proved by verifying the frequency domain conditions.

  11. Observations of HF backscatter decay rates from HAARP generated FAI

    NASA Astrophysics Data System (ADS)

    Bristow, William; Hysell, David

    2016-07-01

    Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

  12. Search for Oscillation of the Electron-Capture Decay Probability of Pm-142

    SciTech Connect

    Vetter, Paul A; Vetter, Paul; Clark, Roderick; Dvorak, Jan; Freedman, Stuart; Gregorich, Kenneth; Jeppesen, Henrik; Mittelberger, Daniel; Wiedeking, Mathis

    2008-07-03

    We have searched for time modulation of the electron capture decay probability of 142Pm in an attempt to confirm a recent claim from a group at the Gesellschaft fur Schwerionenforschung (GSI). We produced 142Pm via the 124Sn(23Na, 5n)142Pm reaction at the Berkeley 88-Inch Cyclotron with a bombardment time short compared to the reported modulation period. Isotope selection by the Berkeley Gas-filled Separator is followed by implantation and a long period of monitoring the 142Nd K alpha x-rays from the daughter. The decay time spectrum of the x-rays is well-described by a simple exponential and the measured half-life of 40.68(53) seconds is consistent with the accepted value. We observed no oscillatory modulation at the proposed frequency at a level 31 times smaller than that reported by Litvinov (Phys. Lett. B 664 (2008) 162). A literature search for previous experiments that might have been sensitive to the reported modulation uncovered another example in 142Eu electron-capture decay. A reanalysis of the published data shows no oscillatory behavior.

  13. Radiative decay rates of impurity states in semiconductor nanocrystals

    SciTech Connect

    Turkov, Vadim K.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2015-10-15

    Doped semiconductor nanocrystals is a versatile material base for contemporary photonics and optoelectronics devices. Here, for the first time to the best of our knowledge, we theoretically calculate the radiative decay rates of the lowest-energy states of donor impurity in spherical nanocrystals made of four widely used semiconductors: ZnS, CdSe, Ge, and GaAs. The decay rates were shown to vary significantly with the nanocrystal radius, increasing by almost three orders of magnitude when the radius is reduced from 15 to 5 nm. Our results suggest that spontaneous emission may dominate the decay of impurity states at low temperatures, and should be taken into account in the design of advanced materials and devices based on doped semiconductor nanocrystals.

  14. Influences of the astrophysical environment on nuclear decay rates

    SciTech Connect

    Norman, E.B.

    1987-09-01

    In many astronomical environments, physical conditions are so extreme that nuclear decay rates can be significantly altered from their laboratory values. Such effects are relevant to a number of current problems in nuclear astrophysics. Experiments related to these problems are now being pursued, and will be described in this talk. 19 refs., 5 figs.

  15. Uncertainties in Astrophysical β-decay Rates from the FRDM

    SciTech Connect

    Bertolli, M.G.; Möller, P.; Jones, S.

    2014-06-15

    β{sup −}-decay rates are of crucial importance in stellar evolution and nucleosynthesis, as they are a key component in stellar processes. Tabulated values of the decay rates as functions of both temperature T and density ρ are necessary input to stellar evolution codes such as MESA, or largescale nucleosynthesis simulations such as those performed by the NuGrid collaboration. Therefore, it is interesting to know the uncertainties in these rates and the effects of these uncertainties on stellar structure and isotopic yields. We have calculated β-strength functions and reaction rates for nuclei ranging from {sup 16}O to {sup 339}136, extending from the proton drip line to the neutron drip line based on a quasi-particle random-phase approximation (QRPA) in a deformed folded-Yukawa single-particle model. Q values are determined from the finite-range droplet mass model (FRDM). We have investigated the effect of model uncertainty on astrophysical β{sup −}-decay rates calculated by the FRDM. The sources of uncertainty considered are Q values and deformation. The rates and their uncertainties are generated for a variety of temperature and density ranges, corresponding to key stellar processes. We demonstrate the effects of these rate uncertainties on isotopic abundances using the NuGrid network calculations.

  16. Determination of K-capture Probability in the Decay of {sup 139}Ce

    SciTech Connect

    Ganbaatar, N.; Ichinkhorloo, D.; Tserenchimeg, E.

    2009-03-31

    We have been studying the KX and gamma rays spectra in the electron capture decay of {sup 139}Ce{yields}{sup 139}La, which were measured by Ge-spectrometer. The absolute intensity of KX and the 165.8 keV gamma rays has been determined and the known conversion coefficients of the 165.8 keV gamma transition of {sup 139}La were used. The probability P{sub K} was determined as 0.755{+-}0.054. Our results have good agreement with the results of other works.

  17. 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.

  18. Materials Outgassing Rate Decay in Vacuum at Isothermal Conditions

    NASA Technical Reports Server (NTRS)

    Huang, Alvin Y.; Kastanas, George N.; Kramer, Leonard; Soares, Carlos E.; Mikatarian, Ronald R.

    2016-01-01

    As a laboratory for scientific research, the International Space Station has been in Low Earth Orbit for nearly 20 years and is expected to be on-orbit for another 10 years. The ISS has been maintaining a relatively pristine contamination environment for science payloads. Materials outgassing induced contamination is currently the dominant source for sensitive surfaces on ISS and modeling the outgassing rate decay over a 20 to 30 year period is challenging. Materials outgassing is described herein as a diffusion-reaction process using ASTM E 1559 rate data. The observation of -1/2 (diffusion) or non-integers (reaction limited) as rate decay exponents for common ISS materials indicate classical reaction kinetics is unsatisfactory in modeling materials outgassing. Non-randomness of reactant concentrations at the interface is the source of this deviation from classical reaction kinetics. A diffusion limited decay was adopted as the result of the correlation of the contaminant layer thicknesses on returned ISS hardware, the existence of high outgassing silicone exhibiting near diffusion limited decay, and the confirmation of non-depleted material after ten years in the Low Earth Orbit.Keywords: Materials Outgassing, ASTM E 1559, Reaction Kinetics, Diffusion, Space Environments Effects, Contamination

  19. Fine and ultrafine particle decay rates in multiple homes.

    PubMed

    Wallace, Lance; Kindzierski, Warren; Kearney, Jill; MacNeill, Morgan; Héroux, Marie-Ève; Wheeler, Amanda J

    2013-11-19

    Human exposure to particles depends on particle loss mechanisms such as deposition and filtration. Fine and ultrafine particles (FP and UFP) were measured continuously over seven consecutive days during summer and winter inside 74 homes in Edmonton, Canada. Daily average air exchange rates were also measured. FP were also measured outside each home and both FP and UFP were measured at a central monitoring station. A censoring algorithm was developed to identify indoor-generated concentrations, with the remainder representing particles infiltrating from outdoors. The resulting infiltration factors were employed to determine the continuously changing background of outdoor particles infiltrating the homes. Background-corrected indoor concentrations were then used to determine rates of removal of FP and UFP following peaks due to indoor sources. About 300 FP peaks and 400 UFP peaks had high-quality (median R(2) value >98%) exponential decay rates lasting from 30 min to 10 h. Median (interquartile range (IQR)) decay rates for UFP were 1.26 (0.82-1.83) h(-1); for FP 1.08 (0.62-1.75) h(-1). These total decay rates included, on average, about a 25% contribution from air exchange, suggesting that deposition and filtration accounted for the major portion of particle loss mechanisms in these homes. Models presented here identify and quantify effects of several factors on total decay rates, such as window opening behavior, home age, use of central furnace fans and kitchen and bathroom exhaust fans, use of air cleaners, use of air conditioners, and indoor-outdoor temperature differences. These findings will help identify ways to reduce exposure and risk. PMID:24143863

  20. 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.

  1. A precision measurement of the rate of muon capture on the deuteron

    NASA Astrophysics Data System (ADS)

    Luo, Xiao

    Because quantum chromodynamics (QCD) is non-perturbative at low energies, strong interactions at the ˜ GeV scale are very challenging to understand. Theoretical progress has been made recently using QCD-based effective field theories (EFT). The short-distance physics of the effective theory is absorbed into a limited number of low energy constants (LECs), which are determined by direct experimental measurement. The MuSun experiment is measuring the rate Lambdad for muon capture on the deuteron, which is the simplest weak interaction in a two nucleon system. Lambda d will be used, in turn, to better determine a fundamental LEC known as dR in the EFT. An improvement in the precision of this LEC will improve our understanding of several other processes in the two-nucleon sector: pp fusion, the main source of energy in the sun and other main-sequence stars and neutrino-deuteron scattering, as observed in the SNO experiment. The MuSun experiment determines Lambdad via a precision measurement of the negative muon lifetime in deuterium. The time difference between an incoming muon, which stops in deuterium, and the subsequent decay electron characterizes the muon disappearance rate. That disappearance rate is the sum of the ordinary muon decay rate and the nuclear capture rate. The ultimate goal of the MuSun experiment is to determine the nuclear capture rate (Lambdad) to a precision of 1.5 %, an order of magnitude improvement over previous efforts. The principal experimental development required to achieve this goal is a cryogenic (T ˜30K) time projection chamber, which not only serves as the deuterium gas target, but also provides an unambiguous measurement of muon stopping position - muons that stop in high Z materials outside the fiducial deuterium volume produce a very large systematic error. The low temperature helps minimize several other systematic errors. The MuSun experiment is taking place at the Paul Scherrer Institut in Villigen, Switzerland. Over the past

  2. Capturing relic neutrinos with {beta}- and double {beta}-decaying nuclei

    SciTech Connect

    Hodak, Rastislav; Kovalenko, Sergey; Simkovic, Fedor

    2009-11-09

    Neutrinos are probably one of the most important structural constituents of the Universe. The Big Bang Theory predicts that the significant component of them is formed by the cosmic neutrino background, an analogues of the big bang relic photons comprising the cosmic microwave background radiation, which has been measured with amazing accuracy. Properties of the relic neutrino background are closely related to the ones of the cosmic microwave radiation. Relic neutrinos pervade space, but their temperature is extremely small, being of the order of 0.1 meV. Although belonging to the most abundant particles of the Universe, the relic neutrinos evade direct detection so far. This is because the low-energy neutrinos interact only very weakly with matter. In this contribution, we explore the feasibility to detect the cosmic neutrino background by means of {beta}-decaying ({sup 3}H and {sup 187}Re) and double beta decaying ({sup 100}Mo) nuclei. In addition, we address the question whether double relic neutrino capture on nuclei can be an obstacle for observation of neutrinoless double {beta}-decay.

  3. Time Modulation of the {beta}{sup +}-Decay Rate of H-Like {sup 140}Pr{sup 58+} Ions

    SciTech Connect

    Ivanov, A. N.; Kryshen, E. L.; Pitschmann, M.; Kienle, P.

    2008-10-31

    Recent experimental data at GSI on the rates of the number of daughter ions, produced by the nuclear K-shell electron capture (EC) decays of the H-like ions {sup 140}Pr{sup 58+} and {sup 142}Pm{sup 60+}, suggest that they are modulated in time with periods T{sub EC}{approx_equal}7 sec and amplitudes a{sub EC}{approx_equal}0.20. Since it is known that these ions are unstable also under the nuclear positron ({beta}{sup +}) decays, we study a possible time dependence of the nuclear {beta}{sup +}-decay rate of the H-like {sup 140}Pr{sup 58+} ion. We show that the time dependence of the {beta}{sup +}-decay rate of the H-like {sup 140}Pr{sup 58+} ion as well as any H-like heavy ions cannot be observed.

  4. The MuCap experiment: A measurement of the muon capture rate in hydrogen gas

    SciTech Connect

    Banks, T. I.

    2007-10-26

    We have recently measured the rate of nuclear muon capture by the proton, using a novel technique which involves a time projection chamber operating in ultraclean, deuterium-depleted hydrogen gas. The target's low gas density of 1% compared to liquid hydrogen is key to avoiding uncertainties that arise from the formation of muonic molecules. The capture rate from the hyperfine singlet ground state of the {mu}p atom was obtained from the difference between the {mu}{sup -} disappearance rate in hydrogen and the world average for the {mu}{sup +} decay rate, yielding {lambda}{sub S} = 725.0{+-}17.4 s{sup -1}, from which the induced pseudoscalar coupling of the nucleon, g{sub P}(q{sup 2} = 0.88m{sub {mu}}{sup 2}) = 7.3{+-}1.1, is extracted. This result is consistent with theoretical predictions for g{sub P} that are based on the approximate chiral symmetry of QCD.

  5. Neutron capture by (94,96)Zr and the decays of (97)Zr and (97)Nb.

    PubMed

    Krane, K S

    2014-12-01

    Cross sections for radiative neutron capture have been determined for (94)Zr and (96)Zr using the activation technique with samples of naturally occurring Zr metal. The sensitivity to the correction for epithermal neutrons in the determination of small thermal cross sections is discussed, particularly in view of the variation in the resonance integral at different sites in the reactor. Gamma-ray spectroscopic studies of the decays of (97)Zr and its daughter (97)Nb have been performed, leading to improved values of the energies and intensities of the emitted γ rays, and correspondingly improved values for the energy levels and β feedings of excited states populated in (97)Nb and (97)Mo. PMID:25103250

  6. New search for double electron capture in {sup 106}Cd decay with the TGV-2 spectrometer

    SciTech Connect

    Briançon, Ch.; Brudanin, V. B.; Egorov, V. G.; Jose, J. M.; Klimenko, A. A.; Kovalik, A.; Rosov, S. V.; Rukhadze, E. N.; Rukhadze, N. I. Salamatin, A. V.; Timkin, V. V.; Fajt, L.; Hodak, R.; Šimkovic, F.; Shitov, Yu. A.; Špavorova, M.; Štekl, I.; Yakushev, E. A.

    2015-09-15

    A new experiment devoted to searches for double electron capture in {sup 106}Cd decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The limit T{sub 1/2}(2νEC/EC) > 2.0×10{sup 20} yr at a 90%confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope {sup 106}Cd to 99.57%. The limits T{sub 1/2}(KL, 2741 keV) > 0.9 × 10{sup 20} yr and T{sub 1/2}(KK, 2718 keV) ≫ 1.4 × 10{sup 20} yr at a 90% C.L. on the neutrinoless decay of {sup 106}Cd were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope {sup 106}Cd.

  7. New search for double electron capture in 106Cd decay with the TGV-2 spectrometer

    NASA Astrophysics Data System (ADS)

    Briançon, Ch.; Brudanin, V. B.; Egorov, V. G.; Jose, J. M.; Klimenko, A. A.; Kovalik, A.; Rosov, S. V.; Rukhadze, E. N.; Rukhadze, N. I.; Salamatin, A. V.; Timkin, V. V.; Fajt, L.; Hodak, R.; Šimkovic, F.; Shitov, Yu. A.; Špavorova, M.; Štekl, I.; Yakushev, E. A.

    2015-09-01

    A new experiment devoted to searches for double electron capture in 106Cd decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The limit T 1/2(2 νEC/EC) > 2.0×1020 yr at a 90%confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope 106Cd to 99.57%. The limits T 1/2(KL, 2741 keV) > 0.9 × 1020 yr and T 1/2(KK, 2718 keV) ≫ 1.4 × 1020 yr at a 90% C.L. on the neutrinoless decay of 106Cd were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope 106Cd.

  8. 31Cl beta decay and the 30P31S reaction rate in nova nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Bennett, Michael; Wrede, C.; Brown, B. A.; Liddick, S. N.; Pérez-Loureiro, D.; NSCL e12028 Collaboration

    2016-03-01

    The 30P31S reaction rate is critical for modeling the final isotopic abundances of ONe nova nucleosynthesis, identifying the origin of presolar nova grains, and calibrating proposed nova thermometers. Unfortunately, this rate is essentially experimentally unconstrained because the strengths of key 31S proton capture resonances are not known, due to uncertainties in their spins and parities. Using a 31Cl beam produced at the National Superconducting Cyclotron Laboratory, we have populated several 31S states for study via beta decay and devised a new decay scheme which includes updated beta feedings and gamma branchings as well as multiple states previously unobserved in 31Cl beta decay. Results of this study, including the unambiguous identification due to isospin mixing of a new l = 0 , Jπ = 3 /2+ 31S resonance directly in the middle of the Gamow Window, will be presented, and significance to the evaluation of the 30P31S reaction rate will be discussed. Work supported by U.S. Natl. Sci. Foundation (Grants No. PHY-1102511, PHY-1404442, PHY-1419765, and PHY-1431052); U.S. Dept. of Energy, Natl. Nucl. Security Administration (Award No. DE-NA0000979); Nat. Sci. and Eng. Research Council of Canada.

  9. Charge-exchange reactions and electron-capture rates for presupernova stellar evolution

    NASA Astrophysics Data System (ADS)

    Zegers, Remco

    2015-04-01

    Weak reaction rates such as electron captures and beta decays play major roles in a variety of astrophysical phenomena, such as core-collapse and thermonuclear supernovae and accreting neutron stars. Consequently, the use of accurate weak reaction rates in astrophysical simulations to understand these phenomena is important. Unfortunately, the number of relevant nuclei is typically very large, and, except for a few special cases, it is impossible to rely on experimental results only: theoretical models must be used to estimate the weak reaction rates. These models can then be benchmarked and improved on the basis of a limited number of experimental data. The most important nuclear structure input that is required for calculating weak reaction rates are Gamow-Teller transition strengths. Although these can be extracted from beta and electron-capture decay data, the energy window accessible by such experiments is limited, if accessible at all. However, at the high temperatures and densities that occur in massive stars prior to the cataclysmic demise, transitions to final states at high excitation energies are important. In addition, to properly test theory, full Gamow-Teller transition strength distributions are very valuable. Fortunately, nature is kind: charge-exchange experiments at intermediate energies can provide the relevant strength distributions over a wide energy window and a variety of charge-exchange probes, such as (p,n), (n,p), (d,2 He) and (t,3 He) have been used to extract strengths of relevance for astrophysics (and for other purposes). This presentation will focus on efforts to validate electron capture rates calculated based on nuclear structure models for nuclei with masses ranging from A ~ 40-65, and on studies aimed at testing astrophysical sensitivities to uncertainties/deviations in the theoretical rates. These efforts include experiments with unstable isotopes, and special gamma-ray coincidence techniques to localize very weak, but

  10. A Self-Organized Model for Cell-Differentiation Based on Variations of Molecular Decay Rates

    PubMed Central

    Hanel, Rudolf; Pöchacker, Manfred; Schölling, Manuel; Thurner, Stefan

    2012-01-01

    Systemic properties of living cells are the result of molecular dynamics governed by so-called genetic regulatory networks (GRN). These networks capture all possible features of cells and are responsible for the immense levels of adaptation characteristic to living systems. At any point in time only small subsets of these networks are active. Any active subset of the GRN leads to the expression of particular sets of molecules (expression modes). The subsets of active networks change over time, leading to the observed complex dynamics of expression patterns. Understanding of these dynamics becomes increasingly important in systems biology and medicine. While the importance of transcription rates and catalytic interactions has been widely recognized in modeling genetic regulatory systems, the understanding of the role of degradation of biochemical agents (mRNA, protein) in regulatory dynamics remains limited. Recent experimental data suggests that there exists a functional relation between mRNA and protein decay rates and expression modes. In this paper we propose a model for the dynamics of successions of sequences of active subnetworks of the GRN. The model is able to reproduce key characteristics of molecular dynamics, including homeostasis, multi-stability, periodic dynamics, alternating activity, differentiability, and self-organized critical dynamics. Moreover the model allows to naturally understand the mechanism behind the relation between decay rates and expression modes. The model explains recent experimental observations that decay-rates (or turnovers) vary between differentiated tissue-classes at a general systemic level and highlights the role of intracellular decay rate control mechanisms in cell differentiation. PMID:22693554

  11. A self-organized model for cell-differentiation based on variations of molecular decay rates.

    PubMed

    Hanel, Rudolf; Pöchacker, Manfred; Schölling, Manuel; Thurner, Stefan

    2012-01-01

    Systemic properties of living cells are the result of molecular dynamics governed by so-called genetic regulatory networks (GRN). These networks capture all possible features of cells and are responsible for the immense levels of adaptation characteristic to living systems. At any point in time only small subsets of these networks are active. Any active subset of the GRN leads to the expression of particular sets of molecules (expression modes). The subsets of active networks change over time, leading to the observed complex dynamics of expression patterns. Understanding of these dynamics becomes increasingly important in systems biology and medicine. While the importance of transcription rates and catalytic interactions has been widely recognized in modeling genetic regulatory systems, the understanding of the role of degradation of biochemical agents (mRNA, protein) in regulatory dynamics remains limited. Recent experimental data suggests that there exists a functional relation between mRNA and protein decay rates and expression modes. In this paper we propose a model for the dynamics of successions of sequences of active subnetworks of the GRN. The model is able to reproduce key characteristics of molecular dynamics, including homeostasis, multi-stability, periodic dynamics, alternating activity, differentiability, and self-organized critical dynamics. Moreover the model allows to naturally understand the mechanism behind the relation between decay rates and expression modes. The model explains recent experimental observations that decay-rates (or turnovers) vary between differentiated tissue-classes at a general systemic level and highlights the role of intracellular decay rate control mechanisms in cell differentiation. PMID:22693554

  12. Isolating the Decay Rate of Cosmological Gravitational Potential

    NASA Astrophysics Data System (ADS)

    Zhang, Pengjie

    2006-08-01

    The decay rate of cosmological gravitational potential measures the deviation from Einstein-de Sitter universe and can put strong constraints on the nature of dark energy and gravity. The usual method to measure this decay rate is through the integrated Sachs-Wolfe (ISW) effect-large-scale structure (LSS) cross-correlation. However, the interpretation of the measured correlation signal is complicated by galaxy bias and the matter power spectrum. This could bias and/or degrade its constraints on the nature of dark energy and gravity. But combining the lensing-LSS cross-correlation measurements, the decay rate of gravitational potential can be isolated. For any given narrow redshift bin of LSS, the ratio of the two cross-correlations directly measures (dlnDφ/dlna)H(z)/W(χ, χs), where Dφ is the linear growth factor of the gravitational potential, H is the Hubble constant at redshift z, W(χ, χs) is the lensing kernel, and χ and χs are the comoving angular diameter distance to lens and source, respectively. This method is optimal in the sense that (1) the measured quantity is essentially free of systematic errors and is only limited by cosmic variance, and (2) the measured quantity depends only on several cosmological parameters and can be predicted from first principles unambiguously. Although fundamentally limited by the inevitably large cosmic variance associated with the ISW measurements, it can still put useful independent constraints on the amount of dark energy and its equation of state. It can also provide a powerful test of modified gravity and can distinguish the Dvali-Gabadadze-Porrati model from ΛCDM at >2.5 σ confidence level.

  13. Double-Beta Decay of 96Zr and Double-Electron Capture of 156Dy to Excited Final States

    NASA Astrophysics Data System (ADS)

    Finch, Sean W.

    Two separate experimental searches for second-order weak nuclear decays to excited final states were conducted. Both experiments were carried out at the Kimballton Underground Research Facility to provide shielding from cosmic rays. The first search is for the two-neutrino double-beta decay of 96Zr to excited final states of the daughter nucleus, 96Mo. As a by product of this experiment, the beta decay of 96Zr was also investigated. Two coaxial high-purity germanium detectors were used in coincidence to detect gamma rays produced by the daughter nucleus as it de-excited to the ground state. After collecting 1.92 years of data with 17.91 g of enriched 96Zr, half-life limits at the level of 10 20 yr were produced. Measurements of this decay are important to test neutrinoless double-beta decay nuclear matrix element calculations, which are necessary to extract the neutrino mass from a measurement of the neutrinoless double-beta decay half-life. The second experiment is a search for the resonantly-enhanced neutrinoless double-electron capture decay of 156Dy to excited states in 156Gd. Double-electron capture is a possible experimental alternative to neutrinoless-double beta decay, which could distinguish the Dirac or Majorana nature of the neutrino. Two clover high-purity germanium detectors were used in coincidence to investigate the decay. A 213.5 mg enriched 156Dy sample was observed for 0.635 year, producing half-life limits of 10 17 yr. The limits produced by both of these experiments are currently the most stringent limits available for these decays.

  14. Solvent Polarity Effect on Nonradiative Decay Rate of Thioflavin T.

    PubMed

    Stsiapura, Vitali I; Kurhuzenkau, Siarhei A; Kuzmitsky, Valery A; Bouganov, Oleg V; Tikhomirov, Sergey A

    2016-07-21

    It has been established earlier that fluorescence quantum yield of thioflavin T (ThT)-a probe widely used for amyloid fibrils detection-is viscosity-dependent, and photophysical properties of ThT can be well-described by the fluorescent molecular rotor model, which associates twisted internal charge transfer (TICT) reaction with the main nonradiative decay process in the excited state of the dye. Solutions of ThT in a range of polar solvents were studied using steady-state fluorescence and sub-picosecond transient absorption spectroscopy methods, and we showed that solvent effect on nonradiative transition rate knr cannot be reduced to the dependence on viscosity only and that ∼3 times change of knr can be observed for ThT in aprotic solvents and water, which correlates with solvent polarity. Different behavior was observed in alcohol solutions, particularly in longer n-alcohols, where TICT rate was mainly determined by rotational diffusion of ThT fragments. Quantum-chemical calculations of S0 → S1 transition energy were performed to get insight of polar solvent contribution to the excited-state energy stabilization. Effect of polar solvent on electronic energy levels of ThT was simulated by applying homogeneous electric field according to the Onsager cavity model. Static solvent effect on the excited-state potential energy surface, where charge transfer reaction takes place, was not essential to account for experimentally observed TICT rate differences in water and aprotic solvents. From the other side, nonradiative decay rate of ThT in water, ethylene glycol, and aprotic solvents was found to follow dynamics of polar solvation knr ∼ τS(-1), which can explain dependence of the TICT rate on both polarity and viscosity of the solvents. PMID:27351358

  15. Photonuclear and radiative capture reaction rates for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Beard, Mary; Frauendorf, S.; Kaempfer, B.; Scwengner, R.; Wiescher, M.

    2011-10-01

    The vast majority of nuclei heavier than iron are synthesisized via the capture of neutrons. There are however 35 naturally occurring nuclei, including isotopes of Mo and La, located on the neutron-deficient size of the valley of stability. It has been proposed that these nuclei, referred to as p-nuclei, are produced via sequential photo-dissociation reactions in the oxygen-neon shell burning regions of a pre-supernova star. As such, cross sections for p-nuclei production are particularly sensitive to the gamma-ray strength function, which, though dominated by the giant dipole resonance, may contain extra strength contributions near to the neutron threshold. Recently new (γ, γ') cross section measurements have been performed at the ELBE facility at Helmholtz-Zentrum Dresden-Rossendorf for the nuclei ^92-100Mo, ^88Sr, ^90Zr and ^139La probing the photo-absorption cross section over an energy range 4.5 - 6 MeV, up to the neutron separation threshold. The use of these measurements as a test of existing gamma-ray strength function models, and the consequent impact on p-nuclei production rates, will be discussed.

  16. Strong neutrino cooling by cycles of electron capture and β- decay in neutron star crusts.

    PubMed

    Schatz, H; Gupta, S; Möller, P; Beard, M; Brown, E F; Deibel, A T; Gasques, L R; Hix, W R; Keek, L; Lau, R; Steiner, A W; Wiescher, M

    2014-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, β(-) decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This 'Urca' mechanism has been studied in the context of white dwarfs and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface. PMID:24291788

  17. Strong neutrino cooling by cycles of electron capture and decay in neutron star crusts

    SciTech Connect

    Schatz, Hendrik; Gupta, Sanjib; Moeller, Peter; Beard, Mary; Brown, Edward; Deibel, A. T.; Gasques, Leandro; Hix, William Raphael; Keek, Laurens; Lau, Rita; Steiner, Andrew M; Wiescher, Michael

    2013-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This Urca mechanism has been studied in the context of white dwarfs13 and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models1, 2 computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface.

  18. Parametric control of collision rates and capture rates in geometrically enhanced differential immunocapture (GEDI) microfluidic devices for rare cell capture

    PubMed Central

    Smith, James P.; Lannin, Timothy B.; Syed, Yusef A.; Santana, Steven M.; Kirby, Brian J.

    2013-01-01

    The enrichment and isolation of rare cells from complex samples, such as circulating tumor cells (CTCs) from whole blood, is an important engineering problem with widespread clinical applications. One approach uses a microfluidic obstacle array with an antibody surface functionalization to both guide cells into contact with the capture surface and to facilitate adhesion; geometrically enhanced differential immunocapture is a design strategy in which the array is designed to promote target cell–obstacle contact and minimize other interactions (Gleghorn et al., 2010; Kirby et al., 2012). We present a simulation that uses capture experiments in a simple Hele-Shaw geometry (Santana et al., 2012) to inform a target-cell-specific capture model that can predict capture probability in immunocapture microdevices of any arbitrary complex geometry. We show that capture performance is strongly dependent on the array geometry, and that it is possible to select an obstacle array geometry that maximizes capture efficiency (by creating combinations of frequent target cell–obstacle collisions and shear stress low enough to support capture), while simulatenously enhancing purity by minimizing non-specific adhesion of both smaller contaminant cells (with infrequent cell–obstacle collisions) and larger contaminant cells (by focusing those collisions into regions of high shear stress). PMID:24078270

  19. Enhanced capture rate for haze defects in production wafer inspection

    NASA Astrophysics Data System (ADS)

    Auerbach, Ditza; Shulman, Adi; Rozentsvige, Moshe

    2010-03-01

    involved scanning with three different recipe types: Standard Inspection: Nominal recipe with a low false alarm rate was used to scan the wafer and repeaters were extracted from the final defect map. Haze Monitoring Application: Recipe sensitivity was enhanced and run on a single field column from which on repeating defects were extracted. Enhanced Repeater Extractor: Defect processing included the two parallel routes: a nominal recipe for the random defects and the new high sensitive repeater extractor algorithm. The results showed that the new application (recipe #3) had the highest capture rate on haze defects and detected new repeater defects not found in the first two recipes. In addition, the recipe was much simpler to setup since repeaters are filtered separately from random defects. We expect that in the future, with the advent of mask-less lithography and EUV lithography, the monitoring of field and die repeating defects on the wafer will become a necessity for process control in the semiconductor fab.

  20. Decay Rate for Travelling Waves of a Relaxation Model

    NASA Astrophysics Data System (ADS)

    Liu, Hailiang; Woo, Ching Wah; Yang, Tong

    1997-03-01

    A relaxation model was proposed in [Shi Jin and Zhouping Xin,Comm. Pure Appl. Math.48(1995), 555-563] to approximate the hyperbolic systems numerically under the subcharacteristic condition introduced in [T. P. Liu,Comm. Math. Phys.108(1987), 153-175]. The stability of travelling waves with strong shock profile and integral zero was proved in [H. L. Liu, J. H. Wang, and T. Yang, Stability in a relaxation model with nonconvex flux, preprint, 1996; H. L. Liu and J. Wang, Asymptotic stability of travelling wave solutions of a hyperbolic system with relaxation terms, preprint, 1995] when the original system is scalar. In this paper, we study the rate of the asymptotic convergence speed of thse travelling wave solutions. The analysis applies to the case of a nonconvex flux and when the shock speed coincides with characteristic speed of the state at infinity. The decay rate is obtained by applying the energy method and is shown to be the same as the one for the viscous conservation law [A. Matsumura and K. Nishihara,Comm. Math. Phys.165(1994), 83-96].

  1. Revisiting the {sup 238}U Thermal Capture Cross Section and Gamma-Ray Emission Probabilities from {sup 239}Np Decay

    SciTech Connect

    Trkov, A.; Molnar, G.L.; Revay, Zs.; Mughabghab, S.F.; Firestone, R.B.; Pronyaev, V.G.; Nichols, A.L.; Moxon, M.C

    2005-07-15

    The precise value of the thermal capture cross section of {sup 238}U is uncertain, and evaluated cross sections from various sources differ by more than their assigned uncertainties. A number of the original publications have been reviewed to assess the discrepant data, corrections were made for more recent standard cross sections and other constants, and one new measurement was analyzed. Because of the strong correlations in activation measurements, the gamma-ray emission probabilities from the {beta}{sup -} decay of {sup 239}Np were also analyzed. As a result of the analysis, a value of 2.683 {+-} 0.012 b was derived for the thermal capture cross section of {sup 238}U. A new evaluation of the gamma-ray emission probabilities from {sup 239}Np decay was also undertaken.

  2. Revisiting the U-238 thermal capture cross section and gamma-raymission probabilities from Np-239 decay

    SciTech Connect

    Trkov, A.; Molnar, G.L.; Revay, Zs.; Mughabghab, S.F.; Firestone,R.B.; Pronyaev, V.G.; Nichols, A.L.; Moxon, M.C.

    2005-03-03

    The precise value of the thermal capture cross section of238U is uncertain, and evaluated cross sections from various sourcesdiffer by more than their assigned uncertainties. A number of theoriginal publications have been reviewed to assess the discrepant data,corrections were made for more recent standard cross sections andotherconstants, and one new measurement was analyzed. Due to the strongcorrelations in activation measurements, the gamma-ray emissionprobabilities from the beta decay of 239Np were also analyzed. As aresult of the analysis, a value of 2.683 +- 0.012 barns was derived forthe thermal capture cross section of 238U. A new evaluation of thegamma-ray emission probabilities from 239Np decay was alsoundertaken.

  3. GEANT4 simulations for in trap decay spectroscopy for electron capture branching ratio measurements using the TITAN facility

    NASA Astrophysics Data System (ADS)

    Seeraji, Shakil; Andreoiu, C.; Jang, F.; Ma, T.; Chaudhuri, A.; Grossheim, A.; Kwiatkowski, A. A.; Schultz, B. E.; Mane, E.; Gwinner, G.; Dilling, J.; Lennarz, A.; Frekers, D.; Chowdhury, U.; Simon, V. V.; Brunner, T.; Delheij, P.; Simon, M. C.

    2012-10-01

    The TITAN-EC project has developed a unique technique to measure electron capture branching ratios (ECBRs) of short lived intermediate nuclide involved in double beta decay. The ECBR information is important for determination of nuclear matrix elements of double-β decay for both double beta decay (2νββ) and neutrino-less double beta decay (0νββ) processes. An important feature of this technique is the use of open access penning trap. Radioactive ions are stored in the trap and their decays are observed. Electrons produced from β decay are guided out of the trap by the Penning trap's strong magnetic field and the x-ray from EC are detected by seven Si(Li) detectors placed radially around trap using thin Be windows. This set-up provides a lower background for the x-ray detection compared to earlier ECBC measurements where the beam is implanted in mylar tape. Detailed GEANT4 simulations have been performed to characterize the efficiency of the detectors and understand their response. In addition the impact of different sizes and shapes of the ion cloud inside the trap has also been investigated to optimize the experimental set-up.

  4. 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.

  5. Time decay rates for the equations of the compressible heat-conductive flow through porous media

    NASA Astrophysics Data System (ADS)

    Chen, Qing; Tan, Zhong; Wu, Guochun

    2015-11-01

    We consider the time decay rates of smooth solutions to the Cauchy problem for the equations of the compressible heat-conductive flow through porous media. We prove the global existence and uniqueness of the solutions by the standard energy method. Moreover, we establish the optimal decay rates of the solution as well as its higher-order spatial derivatives. And the damping effect on the time decay rates of the solution is studied in detail.

  6. Effect of room air recirculation delay on the decay rate of tracer gas concentration

    SciTech Connect

    Kristoffersen, A.R.; Gadgil, A.J.; Lorenzetti, D.M.

    2004-05-01

    Tracer gas measurements are commonly used to estimate the fresh air exchange rate in a room or building. Published tracer decay methods account for fresh air supply, infiltration, and leaks in ductwork. However, the time delay associated with a ventilation system recirculating tracer back to the room also affects the decay rate. We present an analytical study of tracer gas decay in a well-mixed, mechanically-ventilated room with recirculation. The analysis shows that failing to account for delays can lead to under- or over-estimates of the fresh air supply, depending on whether the decay rate calculation includes the duct volume.

  7. Factors influencing the variation in capture rates of shrews in southern California, USA

    USGS Publications Warehouse

    Laakkonen, J.; Fisher, R.N.; Case, T.J.

    2003-01-01

    We examined the temporal variation in capture rates of shrews Notiosorex crawfordi (Coues, 1877) and Sorex ornatus (Merriam, 1895) in 20 sites representing fragmented and continuous habitats in southern California, USA. In N. crawfordi, the temporal variation was significantly correlated with the mean capture rates. Of the 6 landscape variables analyzed (size of the landscape, size of the sample area, altitude, edge, longitude and latitude), sample area was positively correlated with variation in capture rates of N. crawfordi. In S. ornatus, longitude was negatively correlated with variation in capture rates. Analysis of the effect of precipitation on the short- and long-term capture rates at 2 of the sites showed no correlation between rainfall and capture rates of shrews even though peak number of shrews at both sites were reached during the year of highest amount of rainfall. A key problem confounding capture rates of shrews in southern California is the low overall abundance of both shrew species in all habitats and seasons.

  8. USE OF GEOSTATISTICS TO PREDICT VIRUS DECAY RATES FOR DETERMINATION OF SEPTIC TANK SETBACK DISTANCES

    EPA Science Inventory

    Water samples were collected from 71 public drinking-water supply wells in the Tucson, Arizona, basin. Virus decay rates in the water samples were determined with MS-2 coliphage as a model virus. The correlations between the virus decay rates and the sample locations were shown b...

  9. Electron-capture branch of {sup 100}Tc and tests of nuclear wave functions for double-{beta} decays.

    SciTech Connect

    Sjue, S. K. L.; Melconian, D.; Garcia, A.; Ahmad, I.; Algora, A.; Aysto, J.; Elomaa, V.-V.; Eronen, T.; Hakala, J.; Hoedl, S.; Kankainen, A.; Kessler, T.; Moore, I. D.; Naabe, F.; Penttila, H.; Rahaman, S.; Saastamoinen, A.; Swanson, H. E.; Weber, C.; Triambak, S.; Deryckx, K.; Physics; Univ. of Washington; Texas A&M Univ.; Univ. of Valencia; Hungarian Academy of Sciences; Univ. of Jyvaskyla; Univ. of Michigan

    2008-12-30

    We present a measurement of the electron-capture branch of {sup 100}Tc. Our value, B(EC) = (2.6 {+-} 0.4) x 10{sup -5}, implies that the {sup 100}Mo neutrino absorption cross section to the ground state of {sup 100}Tc is roughly 50% larger than previously thought. Disagreement between the experimental value and QRPA calculations relevant to double-{beta} decay matrix elements persists. We find agreement with previous measurements of the 539.5- and 590.8-keV {gamma}-ray intensities.

  10. Reduced Beta Decay Rates of Iron Isotopes for Supernova Physics

    SciTech Connect

    Nabi, Jameel-Un

    2009-07-07

    During the late phases of stellar evolution beta decay on iron isotopes, in the core of massive stars, plays a crucial role in the dynamics of core-collapse. The beta decay contributes in maintaining a 'respectable' lepton-to-baryon ratio (PSI{sub e}) of the core prior to collapse which results in a larger shock energy to power the explosion. It is indeed a fine tuning of the parameter PSI{sub e} at various stages of supernova physics which can lead to a successful transformation of the collapse into an explosion. The calculations presented here might help in fine-tuning of PSI{sub e} for the collapse simulators of massive stars.

  11. Statistical properties of aftershock rate decay: Implications for the assessment of continuing activity

    NASA Astrophysics Data System (ADS)

    Adamaki, Aggeliki; Papadimitriou, Eleftheria; Tsaklidis, George; Karakostas, Vassilios

    2011-08-01

    Aftershock rates seem to follow a power law decay, but the assessment of the aftershock frequency immediately after an earthquake, as well as during the evolution of a seismic excitation remains a demand for the imminent seismic hazard. The purpose of this work is to study the temporal distribution of triggered earthquakes in short time scales following a strong event, and thus a multiple seismic sequence was chosen for this purpose. Statistical models are applied to the 1981 Corinth Gulf sequence, comprising three strong (M = 6.7, M = 6.5, and M = 6.3) events between 24 February and 4 March. The non-homogeneous Poisson process outperforms the simple Poisson process in order to model the aftershock sequence, whereas the Weibull process is more appropriate to capture the features of the short-term behavior, but not the most proper for describing the seismicity in long term. The aftershock data defines a smooth curve of the declining rate and a long-tail theoretical model is more appropriate to fit the data than a rapidly declining exponential function, as supported by the quantitative results derived from the survival function. An autoregressive model is also applied to the seismic sequence, shedding more light on the stationarity of the time series.

  12. Application of the t-model of optimal prediction to the estimationof the rate of decay of solutions of the Euler equations in two and threedimensions

    SciTech Connect

    Hald, Ole H.; Shvets, Yelena; Stinis, Panagiotis

    2006-10-07

    The "t-model" for dimensional reduction is applied to theestimation of the rate of decay of solutions of the Burgers equation andof the Euler equations in two and three space dimensions. The model wasfirst derived in a statistical mechanics context, but here we analyze itpurely as a numerical tool and prove its convergence. In the Burgers casethe model captures the rate of decay exactly, as was already previouslyshown. For the Euler equations in two space dimensions, the modelpreserves energy as it should. In three dimensions, we find a power lawdecay in time and observe a temporal intermittency.

  13. Investigation of photoneutron and capture gamma-ray production in Pb and W under irradiation from 16N decay radiation

    NASA Astrophysics Data System (ADS)

    Kebwaro, Jeremiah Monari; Zhao, Yaolin; He, Chaohui

    2015-09-01

    Lead and tungsten are potential alternative materials for shielding reactor ex-core components with high 16N activity when available space limits application of concrete. Since the two materials are vulnerable to photonuclear reactions, the nature and intensity of the secondary radiation resulting from (γ,n) and (n,γ) reactions when 16N decay radiation interact with these materials need to be well known for effective shielding design. In this study the MCNP code was used to calculate the photoneutron and capture gamma-ray spectra in the two materials when irradiated by 16N decay radiation. It was observed that some of the photoneutrons generated in the two materials lie in the low-energy range which is considered optimum for (n,γ) reactions. Lead is more transparent to the photoneutrons when compared to tungsten. The calculations also revealed that the bremsstrahlung generated by the beta spectrum was not sufficient to trigger any additional photoneutrons. Both energetic and less energetic capture gamma-rays are observed when photoneutrons interact with nuclei of the two materials. Depending on the strength of the 16N source term, the secondary radiation could affect the effectiveness of the shield and need to be considered during design.

  14. Biomass decay rates and tissue nutrient loss in bloom and non-bloom-forming macroalgal species

    NASA Astrophysics Data System (ADS)

    Conover, Jessie; Green, Lindsay A.; Thornber, Carol S.

    2016-09-01

    Macroalgal blooms occur in shallow, low-wave energy environments and are generally dominated by fast-growing ephemeral macroalgae. When macroalgal mats undergo senescence and decompose they can cause oxygen depletion and release nutrients into the surrounding water. There are relatively few studies that examine macroalgal decomposition rates in areas impacted by macroalgal blooms. Understanding the rate of macroalgal bloom decomposition is essential to understanding the impacts of macroalgal blooms following senescence. Here, we examined the biomass, organic content, nitrogen decay rates and δ15N values for five macroalgal species (the bloom-forming Agardhiella subulata, Gracilaria vermiculophylla, Ulva compressa, and Ulva rigida and the non-bloom-forming Fucus vesiculosus) in Narragansett Bay, Rhode Island, U.S.A. using a litterbag design. Bloom-forming macroalgae had similar biomass decay rates (0.34-0.51 k d-1) and decayed significantly faster than non-bloom-forming macroalgae (0.09 k d-1). Biomass decay rates also varied temporally, with a significant positive correlation between biomass decay rate and water temperature for U. rigida. Tissue organic content decreased over time in all species, although A. subulata and G. vermiculophylla displayed significantly higher rates of organic content decay than U. compressa, U. rigida, and F. vesiculosus. Agardhiella subulata had a significantly higher rate of tissue nitrogen decay (0.35 k d-1) than all other species. By contrast, only the δ15N of F. vesiculosus changed significantly over the decay period. Overall, our results indicate that bloom-forming macroalgal species decay more rapidly than non-bloom-forming species.

  15. Estimating taxonomic diversity, extinction rates, and speciation rates from fossil data using capture-recapture models

    USGS Publications Warehouse

    Nichols, J.D.; Pollock, K.H.

    1983-01-01

    Capture-recapture models can be used to estimate parameters of interest from paleobiological data when encouter probabilities are unknown and variable over time. These models also permit estimation of sampling variances and goodness-of-fit tests are available for assessing the fit of data to most models. The authors describe capture-recapture models which should be useful in paleobiological analyses and discuss the assumptions which underlie them. They illustrate these models with examples and discuss aspects of study design.

  16. Capture-recapture estimation of prebreeding survival rate for birds exhibiting delayed maturation

    USGS Publications Warehouse

    Nichols, J.D.; Spendelow, J.A.; Hines, J.E.

    1990-01-01

    Many species of seabirds exhibit delayed maturity and do not return to the natal colony to breed for several years after fledging. Capture-recapture studies are frequently conducted at such breeding colonies and often include marking of young birds. However, because of the absence of these birds from the natal colony during the first few years after banding, the data do not fit neatly into existing capture-recapture models. Here we present a method for estimating prebreeding survival rate from capture-recapture studies on species exhibiting such patterns of delayed maturation. We illustrate the method using data from a capture-recapture study of Roseate Terns (Sterna dougallii ) on Falkner Island, Connecticut. The method appears to work well and emphasizes the potential to tailor capture-recapture models to specific field situations.

  17. Calculations on decay rates of various proton emissions

    NASA Astrophysics Data System (ADS)

    Qian, Yibin; Ren, Zhongzhou

    2016-03-01

    Proton radioactivity of neutron-deficient nuclei around the dripline has been systematically studied within the deformed density-dependent model. The crucial proton-nucleus potential is constructed via the single-folding integral of the density distribution of daughter nuclei and the effective M3Y nucleon-nucleon interaction or the proton-proton Coulomb interaction. After the decay width is obtained by the modified two-potential approach, the final decay half-lives can be achieved by involving the spectroscopic factors from the relativistic mean-field (RMF) theory combined with the BCS method. Moreover, a simple formula along with only one adjusted parameter is tentatively proposed to evaluate the half-lives of proton emitters, where the introduction of nuclear deformation is somewhat discussed as well. It is found that the calculated results are in satisfactory agreement with the experimental values and consistent with other theoretical studies, indicating that the present approach can be applied to the case of proton emission. Predictions on half-lives are made for possible proton emitters, which may be useful for future experiments.

  18. Seasonal determinations of algal virus decay rates reveal overwintering in a temperate freshwater pond.

    PubMed

    Long, Andrew M; Short, Steven M

    2016-07-01

    To address questions about algal virus persistence (i.e., continued existence) in the environment, rates of decay of infectivity for two viruses that infect Chlorella-like algae, ATCV-1 and CVM-1, and a virus that infects the prymnesiophyte Chrysochromulina parva, CpV-BQ1, were estimated from in situ incubations in a temperate, seasonally frozen pond. A series of experiments were conducted to estimate rates of decay of infectivity in all four seasons with incubations lasting 21 days in spring, summer and autumn, and 126 days in winter. Decay rates observed across this study were relatively low compared with previous estimates obtained for other algal viruses, and ranged from 0.012 to 11% h(-1). Overall, the virus CpV-BQ1 decayed most rapidly whereas ATCV-1 decayed most slowly, but for all viruses the highest decay rates were observed during the summer and the lowest were observed during the winter. Furthermore, the winter incubations revealed the ability of each virus to overwinter under ice as ATCV-1, CVM-1 and CpV-BQ1 retained up to 48%, 19% and 9% of their infectivity after 126 days, respectively. The observed resilience of algal viruses in a seasonally frozen freshwater pond provides a mechanism that can support the maintenance of viral seed banks in nature. However, the high rates of decay observed in the summer demonstrate that virus survival and therefore environmental persistence can be subject to seasonal bottlenecks. PMID:26943625

  19. Muon capture rates on O-16 leading to bound states of N-16.

    NASA Technical Reports Server (NTRS)

    Kane, F. R.; Eckhause, M.; Miller, G. H.; Roberts, B. L.; Vislay, M. E.; Welsh, R. E.

    1973-01-01

    A low-energy spectrum of gamma-rays following muon capture in O-16 was obtained with a high-resolution 1 cu cm Ge(Li) detector. The graph of the spectrum shows the separation of contaminant peaks from the 120 keV N-16 line. It is pointed out that there is a large discrepancy between the capture rate obtained in the investigation and results reported by Deutsch et al. (1969).

  20. Decay rates and electromagnetic transitions of heavy quarkonia

    NASA Astrophysics Data System (ADS)

    Pandya, J. N.; Soni, N. R.; Devlani, N.; Rai, A. K.

    2015-12-01

    The electromagnetic radiative transition widths for heavy quarkonia, as well as digamma and digluon decay widths, are computed in the framework of the extended harmonic confinement model (ERHM) and Coulomb plus power potential (CPPν) with varying potential index ν. The outcome is compared with the values obtained from other theoretical models and experimental results. While the mass spectra, digamma and digluon widths from ERHM as well as CPPν=1 are in good agreement with experimental data, the electromagnetic transition widths span over a wide range for the potential models considered here making it difficult to prefer a particular model over the others because of the lack of experimental data for most transition widths. Supported by University Grants Commission, India for Major Research Project F. No.42-775/2013(SR) (J N Pandya) and Dept. of Science and Technology, India, under SERC fast track scheme SR/FTP/PS-152/2012 (A K Rai)

  1. Beta decay rates of neutron-rich nuclei

    SciTech Connect

    Marketin, Tomislav; Huther, Lutz; Martínez-Pinedo, Gabriel

    2015-10-15

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. Currently, a single large-scale calculation is available based on a QRPA calculation with a schematic interaction on top of the Finite Range Droplet Model. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei.

  2. Beta decay rates of neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Marketin, Tomislav; Huther, Lutz; Petković, Jelena; Paar, Nils; Martínez-Pinedo, Gabriel

    2016-06-01

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.

  3. Complex Configuration Effects on β-DECAY Rates

    NASA Astrophysics Data System (ADS)

    Severyukhin, A. P.; Voronov, V. V.; Borzov, I. N.; Arsenyev, N. N.; van Giai, Nguyen

    2015-06-01

    Starting from a Skyrme interaction the Gamow-Teller (GT) strength in the Qβ- window has been studied within a microscopic model including the 2p-2h configuration effects. The suggested approach enables one to perform the calculations in very large configuration spaces. As a result, the β--decay halflife is decreased due to the 2p - 2h fragmentation of GT states. Using the Skyrme interaction SGII with tensor terms we study this reduction effect for the neutron-rich N = 82 isotones below the doubly magic nucleus 132Sn. Predictions are given for 126Ru and 128Pd in comparison to 130Cd which is the r-process waiting-point nucleus.

  4. Continuum-state and bound-state β--decay rates of the neutron

    NASA Astrophysics Data System (ADS)

    Faber, M.; Ivanov, A. N.; Ivanova, V. A.; Marton, J.; Pitschmann, M.; Serebrov, A. P.; Troitskaya, N. I.; Wellenzohn, M.

    2009-09-01

    For the β--decay of the neutron we analyze the continuum-state and bound-state decay modes. We calculate the decay rates, the electron energy spectrum for the continuum-state decay mode, and angular distributions of the decay probabilities for the continuum-state and bound-state decay modes. The theoretical results are obtained for the new value for the axial coupling constant gA=1.2750(9), obtained recently by H. Abele [Prog. Part. Nucl. Phys. 60, 1 (2008)] from the fit of the experimental data on the coefficient of the correlation of the neutron spin and the electron momentum of the electron energy spectrum of the continuum-state decay mode. We take into account the contribution of radiative corrections and the scalar and tensor weak couplings. The calculated angular distributions of the probabilities of the bound-state decay modes of the polarized neutron can be used for the experimental measurements of the bound-state β--decays into the hyperfine states with total angular momentum F=1 and scalar and tensor weak coupling constants.

  5. Prolonged decay of molecular rate estimates for metazoan mitochondrial DNA

    PubMed Central

    Ho, Simon Y.W.

    2015-01-01

    Evolutionary timescales can be estimated from genetic data using the molecular clock, often calibrated by fossil or geological evidence. However, estimates of molecular rates in mitochondrial DNA appear to scale negatively with the age of the clock calibration. Although such a pattern has been observed in a limited range of data sets, it has not been studied on a large scale in metazoans. In addition, there is uncertainty over the temporal extent of the time-dependent pattern in rate estimates. Here we present a meta-analysis of 239 rate estimates from metazoans, representing a range of timescales and taxonomic groups. We found evidence of time-dependent rates in both coding and non-coding mitochondrial markers, in every group of animals that we studied. The negative relationship between the estimated rate and time persisted across a much wider range of calibration times than previously suggested. This indicates that, over long time frames, purifying selection gives way to mutational saturation as the main driver of time-dependent biases in rate estimates. The results of our study stress the importance of accounting for time-dependent biases in estimating mitochondrial rates regardless of the timescale over which they are inferred. PMID:25780773

  6. Electron capture decay of 58-min U-229(92) and levels in Pa-229(91)

    SciTech Connect

    Ahmad, I.; Chasman, R. R.; Greene, J. P.; Kondev, F. G.; Zhu, S.

    2015-08-17

    Electron capture decay of U-229 is investigated by measuring the gamma-ray and conversion electron spectra of mass-separated and unseparated U-229 sources with high-resolution germanium and silicon detectors, respectively. Gamma-gamma coincidence measurements are also performed using germanium detectors. These studies provide level energies and level ordering in Pa-229. Single-particle assignments are given to these levels which are in agreement with the systematics in this region and also with theory. In a previous study, we report the observation of a 5/2(+/-) parity doublet in the Pa-229 ground state, which is a signature of octupole deformation. The present analysis of the data still shows a splitting of 60 +/- 50 eV, but with this large uncertainty the existence of the doublet is not certain.

  7. Neutrino energy loss rates and positron capture rates on {sup 55}Co for presupernova and supernova physics

    SciTech Connect

    Nabi, Jameel-Un; Sajjad, Muhammad

    2008-05-15

    Proton-neutron quasiparticle random phase approximation (pn-QRPA) theory has recently been used for the calculation of stellar weak interaction rates of the fp-shell nuclide with success. Neutrino losses from protoneutron stars play a pivotal role in deciding if these stars would be crushed into black holes or explode as supernovas. The product of abundance and positron capture rates on {sup 55}Co is substantial and as such can play a role in the fine tuning of input parameters of simulation codes especially in the presupernova evolution. Recently we introduced our calculation of capture rates on {sup 55}Co, in a luxurious model space of 7({Dirac_h}/2{pi}) {omega}, employing the pn-QRPA theory with a separable interaction. Simulators, however, may require these rates on a fine scale. Here we present for the first time an expanded calculation of the neutrino energy loss rates and positron capture rates on {sup 55}Co on an extensive temperature-density scale. This type of scale is appropriate for interpolation purposes and of greater utility for simulation codes. The pn-QRPA calculated neutrino energy loss rates are enhanced roughly up to two orders of magnitude compared with the large-scale shell model calculations and favor a lower entropy for the core of massive stars.

  8. Seasonal variations of decay rate measurement data and their interpretation.

    PubMed

    Schrader, Heinrich

    2016-08-01

    Measurement data of long-lived radionuclides, for example, (85)Kr, (90)Sr, (108m)Ag, (133)Ba, (152)Eu, (154)Eu and (226)Ra, and particularly the relative residuals of fitted raw data from current measurements of ionization chambers for half-life determination show small periodic seasonal variations with amplitudes of about 0.15%. The interpretation of these fluctuations is a matter of controversy whether the observed effect is produced by some interaction with the radionuclides themselves or is an artifact of the measuring chain. At the origin of such a discussion there is the exponential decay law of radioactive substances used for data fitting, one of the fundamentals of nuclear physics. Some groups of physicists use statistical methods and analyze correlations with various parameters of the measurement data and, for example, the Earth-Sun distance, as a basis of interpretation. In this article, data measured at the Physikalisch-Technische Bundesanstalt and published earlier are the subject of a correlation analysis using the corresponding time series of data with varying measurement conditions. An overview of these measurement conditions producing instrument instabilities is given and causality relations are discussed. The resulting correlation coefficients for various series of the same radionuclide using similar measurement conditions are in the order of 0.7, which indicates a high correlation, and for series of the same radionuclide using different measurement conditions and changes of the measuring chain of the order of -0.2 or even lower, which indicates an anti-correlation. These results provide strong arguments that the observed seasonal variations are caused by the measuring chain and, in particular, by the type of measuring electronics used. PMID:27258217

  9. Hawking-Moss Bounces and Vacuum Decay Rates

    SciTech Connect

    Weinberg, Erick J.

    2007-06-22

    The conventional interpretation of the Hawking-Moss (HM) solution implies a transition rate between vacua that depends only on the values of the potential in the initial vacuum and at the top of a potential barrier, leading to the implausible conclusion that transitions to distant vacua can be as likely as those to a nearby one. I analyze this issue using a nongravitational example with analogous properties. I show that such HM bounces do not give reliable rate calculations, but are instead related to the probability of finding a quasistable configuration at a local potential maximum.

  10. Impact of the dark matter velocity distribution on capture rates in the Sun

    SciTech Connect

    Choi, K.; Itow, Y.; Rott, C. E-mail: rott@skku.edu

    2014-05-01

    Dark matter could be captured in the Sun and self-annihilate, giving rise to an observable neutrino flux. Indirect searches for dark matter looking for this signal with neutrino telescopes have resulted in tight constraints on the interaction cross-section of dark matter with ordinary matter. We investigate how robust limits are against astro-physical uncertainties. We study the effect of the velocity distribution of dark matter in our Galaxy on capture rates in the Sun. We investigate four sources of uncertainties: orbital speed of the Sun, escape velocity of dark matter from the halo, dark matter velocity distribution functions and existence of a dark disc. We find that even extreme cases currently discussed do not decrease the sensitivity of indirect detection significantly because the capture is achieved over a broad range of the velocity distribution by integration over the velocity distribution. The effect of the uncertainty in the high-velocity tail of dark matter halo is very marginal as the capture process is rather inefficient at this region. The difference in capture rate in the Sun for various scenarios is compared to the expected change in event rates for direct detection. The possibility of co-rotating structure with the Sun can largely boost the signal and hence makes the interpretation of indirect detection conservative compared to direct detection.

  11. WEST NILE VIRUS ANTIBODY DECAY RATE IN FREE-RANGING BIRDS.

    PubMed

    McKee, Eileen M; Walker, Edward D; Anderson, Tavis K; Kitron, Uriel D; Brawn, Jeffrey D; Krebs, Bethany L; Newman, Christina; Ruiz, Marilyn O; Levine, Rebecca S; Carrington, Mary E; McLean, Robert G; Goldberg, Tony L; Hamer, Gabriel L

    2015-07-01

    Antibody duration, following a humoral immune response to West Nile virus (WNV) infection, is poorly understood in free-ranging avian hosts. Quantifying antibody decay rate is important for interpreting serologic results and for understanding the potential for birds to serorevert and become susceptible again. We sampled free-ranging birds in Chicago, Illinois, US, from 2005 to 2011 and Atlanta, Georgia, US, from 2010 to 2012 to examine the dynamics of antibody decay following natural WNV infection. Using serial dilutions in a blocking enzyme-linked immunosorbent assay, we quantified WNV antibody titer in repeated blood samples from individual birds over time. We quantified a rate of antibody decay for 23 Northern Cardinals (Cardinalis cardinalis) of 0.198 natural log units per month and 24 individuals of other bird species of 0.178 natural log units per month. Our results suggest that juveniles had a higher rate of antibody decay than adults, which is consistent with nonlinear antibody decay at different times postexposure. Overall, most birds had undetectable titers 2 yr postexposure. Nonuniform WNV antibody decay rates in free-ranging birds underscore the need for cautious interpretation of avian serology results in the context of arbovirus surveillance and epidemiology. PMID:25919465

  12. Vitamin C: Rate of Decay and Stability Characteristics

    ERIC Educational Resources Information Center

    Kakis, Frederic J.; Rossi, Carl J.

    1974-01-01

    Describes an experiment designed to provide the opportunity for studying some of the parameters affecting the stability of Vitamin C in various environments, and to acquaint the student with an experimental procedure for studying simple reaction kinetics and the calculations of specific rate constants. (Author/JR)

  13. Spectra and decay rates of bb¯ meson using Gaussian wave function

    NASA Astrophysics Data System (ADS)

    Rai, Ajay Kumar; Devlani, Nayneshkumar; Kher, Virendrasinh H.

    2015-05-01

    Using the Gaussian wave function mass spectra and decay rates of bb¯ meson are investigated in the framework of phenomenological quark anti-quark potential (coulomb plus power) model consisting of relativistic corrections to the kinetic energy term. The spin-spin, spin-orbit and tensor interactions are employed to obtain the pseudoscalar and vector meson masses. The decay constants (fP/V) are computed using the wave function at the origin. The di-gamma and di-leptonic decays of the bb¯ meson are investigated using Van-Rayan Weisskopf formula as well as in the NRQCD formalism.

  14. Total radiative capture rates for three- and four-nucleon pionic atoms

    SciTech Connect

    Werntz, C.; Valk, H.S.

    1988-02-01

    A corrected closure approximation is used to calculate the reduced rates for radiative capture of negative pions from 1s and 2p orbitals in /sup 3/H, /sup 3/He, and /sup 4/He. For /sup 3/He and /sup 4/He the calculated rates are in good agreement with experimental data. In the case of /sup 3/H, the calculated value for 1s capture is combined with the measured radiative capture branching ratio to obtain a value of GAMMA/sub tot//sup 1//sup s/ = 2.2 +- 0.4 eV for the total width of the 1s level in the /sup 3/H pionic atom. This value when compared to the measured total width of the 1s level in pionic /sup 3/He implies a small but definite contribution of singlet spin nucleon pairs to absorption of s-wave pions.

  15. Neutron capture cross-section studies of Tellurium isotopes for neutrinoless double beta decay applications

    NASA Astrophysics Data System (ADS)

    Bhike, Megha; Tornow, Werner

    2014-09-01

    The CUORE detector at Gran Sasso, aimed at searching for neutrinoless double-beta decay of 130Te, employs an array of TeO2 bolometer modules. To understand and identify the contribution of muon and (α,n) induced neutrons to the CUORE background, fast neutron cature cross-section data of the tellurium isotopes 126Te, 128Te and 130Te have been measured with the activation method at eight different energies in the neutron energy range 0.5-7.5 MeV. Plastic pill boxes of diameter 1.6 cm and width 1 cm containing Te were irradiated with mono-energetic neutrons produced via the 3H(p,n)3He and 2H(d,n)3He reactions. The cross-sections were determined relative to the 197Au(n, γ)198Au and 115In(n,n')115m In standard cross sections. The activities of the products were measured using 60% lead-shielded HPGe detectors at TUNL's low background counting facility. The present results are compared with the evaluated data from TENDL-2012, ENDF/B-VII.1, JEFF-3.2 and JENDL-4.0, as well as with literature data.

  16. Comparative capture rate responses of mosquito vectors to light trap and human landing collection methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Capture rate responses of female Aedes albopictus Skuse, Anopheles quadrimaculatus Say, Culex nigripalpus Theobald, Culex quinquefasciatus Say, and Ochlerotatus triseriatus (Wiedemann) to CDC-type light trap (LT) and human landing (HL) collection methods were observed and evaluated for congruency wi...

  17. RATE CONTROLLING PROCESSES AND ENHANCEMENT STRATEGIES IN HUMIDIFICATION FOR DUCT SO2 CAPTURE

    EPA Science Inventory

    The report gives results of an investigation of the fundamental rate processes that govern sulfur capture in power plant ducts during humidification of flue gases. The specific application was the reactivation of partially sulfated calcium-based sorbents from in-furnace injection...

  18. Decay rates of charmonia within a quark-antiquark confining potential

    NASA Astrophysics Data System (ADS)

    Smruti, Patel; Vinodkumar, P. C.; Shashank, Bhatnagar

    2016-05-01

    In this work, we investigate the spectroscopy and decay rates of charmonia within the framework of the non-relativistic Schrödinger equation by employing an approximate inter quark-antiquark potential. The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are employed to compute the spectroscopy of the excited S states and a few low-lying P and D waves. The resultant wave functions at zero inter-quark separation as well as some finite separations are employed to predict the di-gamma, di-leptonic and di-gluon decay rates of charmonia states using the conventional Van Royen-Weisskopf formula. The di-gamma and di-leptonic decay widths are also computed by incorporating the relativistic corrections of order v 4 within the NRQCD formalism. We have observed that the NRQCD predictions with their matrix elements computed at finite radial separation yield results which are found to be in better agreement with experimental values for both di-gamma and di-leptonic decays. The same scenario is seen in the case when di-gamma and di-leptonic decay widths are computed with the Van Royen-Weisskopf formula. It is also observed that the di-gluon decay width with the inclusion of binding energy effects are in better agreement with the experimental data available for 1S-2S and 1P. The di-gluon decay width of 3S and 2P waves waves are also predicted. Thus, the present study of decay rates clearly indicates the importance of binding energy effects. Supported by Major Research Project NO. F. 40-457/2011(SR), UGC, India

  19. Neglected role of fungal community composition in explaining variation in wood decay rates.

    PubMed

    Van der Wal, A; Ottosson, E; De Boer, W

    2015-01-01

    Decomposition of wood is an important component of global carbon cycling. Most wood decomposition models are based on tree characteristics and environmental conditions; however, they do not include community dynamics of fungi that are the major wood decomposers. We examined the factors explaining variation in sapwood decay in oak tree stumps two and five years after cutting. Wood moisture content was significantly correlated with sapwood decay in younger stumps, whereas ITS-based composition and species richness of the fungal community were the best predictors for mass loss in the older stumps. Co-occurrence analysis showed that, in freshly cut trees and in younger stumps, fungal communities were nonrandomly structured, whereas fungal communities in old stumps could not be separated from a randomly assembled community. These results indicate that the most important factors explaining variation in wood decay rates can change over time and that the strength of competitive interactions between fungi in decaying tree stumps may level off with increased wood decay. Our field analysis further suggests that ascomycetes may have a prominent role in wood decay, but their wood-degrading abilities need to be further tested under controlled conditions. The next challenging step will be to integrate fungal community assembly processes in wood decay models to improve carbon sequestration estimates of forests. PMID:26236897

  20. A new theoretical approach to thermonuclear radiative-capture reaction rate

    SciTech Connect

    Funaki, Yasuro; Yabana, Kazuhiro; Akahori, Takahiko

    2012-11-12

    We propose a new computational method for astrophysical reaction rate of radiative capture process, which does not require any solution of scattering problem. It is tested for twobody radiative caputure reaction {sup 16}O({alpha},{gamma}){sup 20}Ne and a comparison is made with an ordinary method solving two-body scattering problem. The method is shown to work well in practice and thus will be useful for problems in which an explicit construction of scattering solution is difficult such as the triple-alpha capture process.

  1. Nonlinear Stability Analysis with Decay Rates of Two Classes of Waves for Conservation Laws.

    NASA Astrophysics Data System (ADS)

    Zingano, Paulo Ricardo

    1990-08-01

    We study in this work the decay rate of disturbances to certain elementary waves for conservation laws when their initial profile is perturbed. In the first problem, rarefaction waves for the scalar equation u_ {t}+f(u)_{x}=u_{xx }, f convex, are considered, and we show that disturbances decay in the L^2 -norm as O(t^{-1/4+mu }), for mu > 0 arbitrarily small, provided they belong to the space L^1cap H^1 initially. The second problem concerns the stability of weak shock waves of a certain class of hyperbolic systems with relaxation, disturbances in this case are shown to decay in L ^2 at certain algebraic rates which depend on how fast they die off as x to +/- infty at initial time, provided they are sufficiently weak. This behavior is due to the compressibility of such waves with respect to the dynamic characteristics governing the propagation of disturbances, a basic feature of shock waves. This result is in vivid contrast to the corresponding one for rarefaction waves, where the decay is ultimately governed by diffusion processes which impose a limit on the overall rate. In both problems treated here, the analysis is based on the derivation of suitable energy inequalities with appropriate decay rates.

  2. Coordinate-dependent diffusion coefficients: Decay rate in open quantum systems

    SciTech Connect

    Sargsyan, V. V.; Palchikov, Yu. V.; Antonenko, N. V.; Kanokov, Z.; Adamian, G. G.

    2007-06-15

    Based on a master equation for the reduced density matrix of an open quantum collective system, the influence of coordinate-dependent microscopical diffusion coefficients on the decay rate from a metastable state is treated. For various frictions and temperatures larger than a crossover temperature, the quasistationary decay rates obtained with the coordinate-dependent microscopical set of diffusion coefficients are compared with those obtained with the coordinate-independent microscopical set of diffusion coefficients and coordinate-independent and -dependent phenomenological sets of diffusion coefficients. Neglecting the coordinate dependence of diffusion coefficients, one can strongly overestimate or underestimate the decay rate at low temperature. The coordinate-dependent phenomenological diffusion coefficient in momentum are shown to be suitable for applications.

  3. Beyond the bucket: testing the effect of experimental design on rate and sequence of decay

    NASA Astrophysics Data System (ADS)

    Gabbott, Sarah; Murdock, Duncan; Purnell, Mark

    2016-04-01

    Experimental decay has revealed the potential for profound biases in our interpretations of exceptionally preserved fossils, with non-random sequences of character loss distorting the position of fossil taxa in phylogenetic trees. By characterising these sequences we can rewind this distortion and make better-informed interpretations of the affinity of enigmatic fossil taxa. Equally, rate of character loss is crucial for estimating the preservation potential of phylogentically informative characters, and revealing the mechanisms of preservation themselves. However, experimental decay has been criticised for poorly modeling 'real' conditions, and dismissed as unsophisticated 'bucket science'. Here we test the effect of a differing experimental parameters on the rate and sequence of decay. By doing so, we can test the assumption that the results of decay experiments are applicable to informing interpretations of exceptionally preserved fossils from diverse preservational settings. The results of our experiments demonstrate the validity of using the sequence of character loss as a phylogenetic tool, and sheds light on the extent to which environment must be considered before making decay-informed interpretations, or reconstructing taphonomic pathways. With careful consideration of experimental design, driven by testable hypotheses, decay experiments are robust and informative - experimental taphonomy needn't kick the bucket just yet.

  4. Neutron Capture Rates near A=130 which Effect a Global Change to the r-Process Abundance Distribution

    SciTech Connect

    Surman, Rebecca; Beun, Joshua; Mclaughlin, Gail C; Hix, William Raphael

    2009-01-01

    We investigate the impact of neutron capture rates near the A=130 peak on the r-process abundance pattern. We show that these capture rates can alter the abundances of individual nuclear species, not only in the region of A=130 peak but also throughout the abundance pattern. We discuss in general the nonequilibrium processes that produce these abundance changes and determine which capture rates have the most significant impact.

  5. High-Rate Data-Capture for an Airborne Lidar System

    NASA Technical Reports Server (NTRS)

    Valett, Susan; Hicks, Edward; Dabney, Philip; Harding, David

    2012-01-01

    A high-rate data system was required to capture the data for an airborne lidar system. A data system was developed that achieved up to 22 million (64-bit) events per second sustained data rate (1408 million bits per second), as well as short bursts (less than 4 s) at higher rates. All hardware used for the system was off the shelf, but carefully selected to achieve these rates. The system was used to capture laser fire, single-photon detection, and GPS data for the Slope Imaging Multi-polarization Photo-counting Lidar (SIMPL). However, the system has applications for other laser altimeter systems (waveform-recording), mass spectroscopy, xray radiometry imaging, high-background- rate ranging lidar, and other similar areas where very high-speed data capture is needed. The data capture software was used for the SIMPL instrument that employs a micropulse, single-photon ranging measurement approach and has 16 data channels. The detected single photons are from two sources those reflected from the target and solar background photons. The instrument is non-gated, so background photons are acquired for a range window of 13 km and can comprise many times the number of target photons. The highest background rate occurs when the atmosphere is clear, the Sun is high, and the target is a highly reflective surface such as snow. Under these conditions, the total data rate for the 16 channels combined is expected to be approximately 22 million events per second. For each photon detection event, the data capture software reads the relative time of receipt, with respect to a one-per-second absolute time pulse from a GPS receiver, from an event timer card with 0.1-ns precision, and records that information to a RAID (Redundant Array of Independent Disks) storage device. The relative time of laser pulse firings must also be read and recorded with the same precision. Each of the four event timer cards handles the throughput from four of the channels. For each detection event, a flag is

  6. Capture locations and growth rates of Atlantic sturgeon in the Chesapeake Bay

    USGS Publications Warehouse

    Welsh, S.A.; Eyler, S.M.; Mangold, M.F.; Spells, A.J.

    2002-01-01

    Little information exists on temporal and spatial distributions of wild and hatchery-reared Atlantic sturgeon Acipenser oxyrinchus oxyrinchus in the Chesapeake Bay. Approximately 3,300 hatchery-reared Atlantic sturgeon comprised of two size groups were released into the Nanticoke River, a tributary of the Chesapeake Bay, on 8 July 1996. During January 1996-May 2000, 1099 Atlantic sturgeon were captured incidentally (i.e., bycatch) by commercial watermen in the Chesapeake Bay, including 420 hatchery-reared individuals. Wild and hatchery-reared Atlantic sturgeon were captured primarily in pound nets and gill nets. Biologists tagged each fish and recorded weight, length, and location of capture. Although two adults greater than 2000 mm fork length (FL) were captured in Maryland waters, wild sturgeon were primarily juveniles from Maryland and Virginia waters (415 and 259 individuals below 1000 mm FL, respectively). A growth rate of 0.565 mm/d (N = 15, SE = 0.081) was estimated for wild individuals (487-944 mm TL at release) at liberty from 30 to 622 d. The average growth of the group of hatchery-reared Atlantic sturgeon raised at 10??C exceeded that of the group raised at 17??C. Our distributional data based on capture locations are biased by fishery dependence and gear selectivity. These data are informative to managers, however, because commercial effort is widely distributed in the Chesapeake Bay, and little distributional data were available before this study.

  7. Efficacy of trap modifications for increasing capture rates of aquatic snakes in floating aquatic funnel traps

    USGS Publications Warehouse

    Halstead, Brian J.; Wylie, Glenn D.; Casazza, Michael L.

    2013-01-01

    Increasing detection and capture probabilities of rare or elusive herpetofauna of conservation concern is important to inform the scientific basis for their management and recovery. The Giant Gartersnake (Thamnophis gigas) is an example of a secretive, wary, and generally difficult-to-sample species about which little is known regarding its patterns of occurrence and demography. We therefore evaluated modifications to existing traps to increase the detection and capture probabilities of the Giant Gartersnake to improve the precision with which occurrence, abundance, survival, and other demographic parameters are estimated. We found that adding a one-way valve constructed of cable ties to the small funnel opening of traps and adding hardware cloth extensions to the wide end of funnels increased capture rates of the Giant Gartersnake by 5.55 times (95% credible interval = 2.45–10.51) relative to unmodified traps. The effectiveness of these modifications was insensitive to the aquatic habitat type in which they were deployed. The snout-vent length of the smallest and largest captured snakes did not vary among trap modifications. These trap modifications are expected to increase detection and capture probabilities of the Giant Gartersnake, and show promise for increasing the precision with which demographic parameters can be estimated for this species. We anticipate that the trap modifications found effective in this study will be applicable to a variety of aquatic and semi-aquatic reptiles and amphibians and improve conservation efforts for these species.

  8. Design of cycler trajectories and analysis of solar influences on radioactive decay rates during space missions

    NASA Astrophysics Data System (ADS)

    Rogers, Blake A.

    This thesis investigates the design of interplanetary missions for the continual habitation of Mars via Earth-Mars cyclers and for the detection of variations in nuclear decay rates due to solar influences. Several cycler concepts have been proposed to provide safe and comfortable quarters for astronauts traveling between the Earth and Mars. However, no literature has appeared to show how these massive vehicles might be placed into their cycler trajectories. Trajectories are designed that use either Vinfinity leveraging or low thrust to establish cycler vehicles in their desired orbits. In the cycler trajectory cases considered, the use of Vinfinity leveraging or low thrust substantially reduces the total propellant needed to achieve the cycler orbit compared to direct orbit insertion. In the case of the classic Aldrin cycler, the propellant savings due to Vinfinity leveraging can be as large as a 24 metric ton reduction for a cycler vehicle with a dry mass of 75 metric tons, and an additional 111 metric ton reduction by instead using low thrust. The two-synodic period cyclers considered benefit less from Vinfinity leveraging, but have a smaller total propellant mass due to their lower approach velocities at Earth and Mars. It turns out that, for low-thrust establishment, the propellant required is approximately the same for each of the cycler trajectories. The Aldrin cycler has been proposed as a transportation system for human missions between Earth and Mars. However, the hyperbolic excess velocity values at the planetary encounters for these orbits are infeasibly large, especially at Mars. In a new version of the Aldrin cycler, low thrust is used in the interplanetary trajectories to reduce the encounter velocities. Reducing the encounter velocities at both planets reduces the propellant needed by the taxis (astronauts use these taxis to transfer between the planetary surfaces and the cycler vehicle) to perform hyperbolic rendezvous. While the propellant

  9. Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy

    SciTech Connect

    Ma Yunzhi; Geng Jinpeng; Gao Song; Bao Shanglian

    2006-12-15

    The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction {sup 10}B(n,{alpha}){sup 7}Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned. Because of the chemical preference of boron-10 carrier molecules, the dose is heterogeneously distributed in cells. In the present work, the (scaled) dose point kernel of boron-11 decay, called {sup 11}B-DPK, was calculated by GEANT4 Monte Carlo simulation code. The DPK curve drops suddenly at the radius of 4.26 {mu}m, the continuous slowing down approximation (CSDA) range of a lithium-7 ion. Then, after a slight ascending, the curve decreases to near zero when the radius goes beyond 8.20 {mu}m, which is the CSDA range of a 1.47 MeV helium-4 ion. With the DPK data, S values for nuclei and cells with the boron-10 on the cell surface are calculated for different combinations of cell and nucleus sizes. The S value for a cell radius of 10 {mu}m and a nucleus radius of 5 {mu}m is slightly larger than the value published by Tung et al. [Appl. Radiat. Isot. 61, 739-743 (2004)]. This result is potentially more accurate than the published value since it includes the contribution of a lithium-7 ion as well as the alpha particle.

  10. Sharp rates of decay of solutions to the nonlinear fast diffusion equation via functional inequalities

    PubMed Central

    Vázquez, J. L.

    2010-01-01

    The goal of this paper is to state the optimal decay rate for solutions of the nonlinear fast diffusion equation and, in self-similar variables, the optimal convergence rates to Barenblatt self-similar profiles and their generalizations. It relies on the identification of the optimal constants in some related Hardy–Poincaré inequalities and concludes a long series of papers devoted to generalized entropies, functional inequalities, and rates for nonlinear diffusion equations. PMID:20823259

  11. Multiwell 14CO2-capture assay for evaluation of substrate oxidation rates of cells in culture.

    PubMed

    Collins, C L; Bode, B P; Souba, W W; Abcouwer, S F

    1998-05-01

    14CO2 capture is commonly used to evaluate the cellular oxidation rate of respiratory substrates. A modification of the established 14CO2-capture method was developed that enables the use of cells in adherent culture and easy analysis of multiple samples under different culture conditions. The use of commercially available culture and filter plates designed for use in a multiplate scintillation spectrophotometer enabled substrate oxidation rates to be evaluated for cells in a 24-well plate format without the need to dislodge the cells from the culture substrate as is required in traditional methods. Evaluation of radioactivity captured in potassium hydroxide-saturated filters was accomplished by adding scintillation fluid to the filter plate wells and counting. Alternatively, filters could be removed and placed in vials for evaluation in a conventional scintillation counter. This method was applied to the oxidation of 14C-glutamine by human breast cell lines and demonstrated concentration-dependent linear accumulation of captured counts. PMID:9591130

  12. Fine-grid calculations for stellar electron and positron capture rates on Fe isotopes

    SciTech Connect

    Nabi, Jameel-Un; Tawfik, Abdel Nasser

    2013-03-15

    The acquisition of precise and reliable nuclear data is a prerequisite to success for stellar evolution and nucleosynthesis studies. Core-collapse simulators find it challenging to generate an explosion from the collapse of the core of massive stars. It is believed that a better understanding of the microphysics of core-collapse can lead to successful results. The weak interaction processes are able to trigger the collapse and control the lepton-to-baryon ratio (Y{sub e}) of the corematerial. It is suggested that the temporal variation of Y{sub e} within the core of a massive star has a pivotal role to play in the stellar evolution and a fine-tuning of this parameter at various stages of presupernova evolution is the key to generate an explosion. During the presupernova evolution of massive stars, isotopes of iron, mainly {sup 54-56}Fe, are considered to be key players in controlling Y{sub e} ratio via electron capture on these nuclides. Recently an improved microscopic calculation of weak-interaction-mediated rates for iron isotopes was introduced using the proton-neutron quasiparticle random-phase-approximation (pn-QRPA) theory. The pn-QRPA theory allows a microscopic state-by-state calculation of stellar capture rates which greatly increases the reliability of calculated rates. The results were suggestive of some fine-tuning of the Y{sub e} ratio during various phases of stellar evolution. Here we present for the first time the fine-grid calculation of the electron and positron capture rates on {sup 54-56}Fe. The sensitivity of the pn-QRPA calculated capture rates to the deformation parameter is also studied in this work. Core-collapse simulators may find this calculation suitable for interpolation purposes and for necessary incorporation in the stellar evolution codes.

  13. First measurements of muon production rate using a novel pion capture system at MuSIC

    NASA Astrophysics Data System (ADS)

    Cook, S.; D'Arcy, R.; Fukuda, M.; Hatanaka, K.; Hino, Y.; Kuno, Y.; Lancaster, M.; Mori, Y.; Nam, T. H.; Ogitsu, T.; Sakamoto, H.; Sato, A.; Truong, N. M.; Yamamoto, A.; Yoshida, M.; Wing, M.

    2013-02-01

    The MuSIC (Muon Science Innovative Channel) beam line at RCNP (Research Centre for Nuclear Physics), Osaka will be the most intense source of muons in the world. A proton beam is incident on a target and, by using a novel capture solenoid, guides the produced pions into the beam line where they subsequently decay to muons. This increased muon flux will allow more precise measurements of cLFV (charged Lepton Flavour Violation) as well as making muon beams more economically feasible. Currently the first 36° of solenoid beam pipe have been completed and installed for testing with low proton current of 1 nA. Measurements of the total particle flux and the muon life time were made. The measurements were taken using thin plastic scintillators coupled to MPPCs (Multi-Pixel Photon Counter) that surrounded a magnesium or copper stopping target. The scintillators were used to record which particles stopped and their subsequent decay times giving a muon yield of 8.5 × 105 muons W-1proton beam or 3 × 108 muons s-1 when using the RCNP's full power (400 W).

  14. Disproof of solar influence on the decay rates of 90Sr/90 Y

    NASA Astrophysics Data System (ADS)

    Kossert, Karsten; Nähle, Ole J.

    2015-09-01

    A custom-built liquid scintillation counter was used for long-term measurements of 90Sr/90 Y sources. The detector system is equipped with an automated sample changer and three photomultiplier tubes, which makes the application of the triple-to-double coincidence ratio (TDCR) method possible. After decay correction, the measured decay rates were found to be stable and no annual oscillation could be observed. Thus, the findings of this work are in strong contradiction to those of Parkhomov (2011) who reported on annual oscillations when measuring 90Sr/90 Y with a Geiger-Müller counter. Sturrock et al. (2012) carried out a more detailed analysis of the experimental data from Parkhomov and claimed to have found correlations between the decay rates and processes inside the Sun. These findings are questionable, since they are based on inappropriate experimental data as is demonstrated in this work. A frequency analysis of our activity data does not show any significant periodicity.

  15. Blackbody-induced decay, excitation and ionization rates for Rydberg states in hydrogen and helium atoms

    NASA Astrophysics Data System (ADS)

    Glukhov, I. L.; Nekipelov, E. A.; Ovsiannikov, V. D.

    2010-06-01

    New features of the blackbody-induced radiation processes on Rydberg atoms were discovered on the basis of numerical data for the blackbody-induced decay Pdnl(T), excitation Penl(T) and ionization Pionnl(T) rates of nS, nP and nD Rydberg states calculated together with the spontaneous decay rates Pspnl in neutral hydrogen, and singlet and triplet helium atoms for some values of the principal quantum number n from 10 to 500 at temperatures from T = 100 K to 2000 K. The fractional rates Rd(e, ion)nl(T) = Pnld(e, ion)(T)/Pspnl equal to the ratio of the induced decay (excitation, ionization) rates to the rate of spontaneous decay were determined as functions of T and n in every series of states with a given angular momentum l = 0, 1, 2. The calculated data reveal an essential difference between the asymptotic dependence of the ionization rate Pionnl(T) and the rates of decay and excitation Pd(e)nl(T)~T/n2. The departures appear in each Rydberg series for n > 100 and introduce appreciable corrections to the formula of Cooke and Gallagher. Two different approximation formulae are proposed on the basis of the numerical data, one for Rd(e)nl(T) and another one for Rionnl(T), which reproduce the calculated values in wide ranges of principal quantum number from n = 10 to 1000 and temperatures between T = 100 K and T = 2000 K with an accuracy of 2% or better. Modified Fues' model potential approach was used for calculating matrix elements of bound-bound and bound-free radiation transitions in helium.

  16. Searches for massive neutrino emission in {sup 14}C beta and {sup 55}Fe electron-capture decays

    SciTech Connect

    Wietfeldt, F.E. |

    1994-05-01

    In 1985 Simpson reported evidence for the emission of a 17 keV mass neutrino in a small fraction of tritium beta decays. An experimental controversy ensued in which a number of both positive and negative results were reported. The beta spectrum of {sup 14}C was collected in a unique {sup 14}C-doped planar germanium detector and a distortion was observed that initially confirmed Simpson`s result. Further tests linked this distortion to a splitting of the collected charge between the central detector and the surrounding guard ring in a fraction of the events. A second {sup 14}C measurement showed no evidence for emission of a 17 keV mass neutrino. In a related experiment, a high statistics electron-capture internal-bremsstrahlung photon spectrum of {sup 55}Fe was collected with a coaxial germanium detector. A local search for departures from a smooth shape near the endpoint was performed, using a second-derivative technique. An upper limit of 0.65% (95% C.L.) for the mixing Of a neutrino in the mass range 5--25 keV was established. The upper limit on the mixing of a 17 keV mass neutrino was 0.14% (95% C.L.).

  17. Informing Neutron-Capture Rates through (d,p) Reactions on Neutron-Rich Tin Isotopes

    NASA Astrophysics Data System (ADS)

    Manning, B.; Cizewski, J. A.; Kozub, R. L.; Ahn, S.; Allmond, J. M.; Bardayan, D. W.; Chae, K. Y.; Chipps, K. A.; Howard, M. E.; Jones, K. L.; Liang, J. F.; Matos, M.; Nunes, F. M.; Nesaraja, C. D.; O'Malley, P. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Ratkiewicz, A.; Schmitt, K. T.; Shapira, D.; Smith, M. S.; Titus, L.

    2014-03-01

    Level energies and spectroscopic information for neutron-rich nuclei provide important input for r-process nucleosynthesis calculations; specifically, the location and strength of single-neutron l = 1 states when calculating neutron-capture rates. Surman and collaborators have performed sensitivity studies to show that varying neutron-capture rates can significantly alter final r-process abundances. However, there are many nuclei important to the r-process that cannot be studied. Extending studies to more neutron-rich nuclei will help constrain the nuclear shell-model in extrapolating to nuclei even further from stability. The (d,p) reaction has been measured with radioactive ion beams of 126Sn and 128Sn to complete the set of (d,p) studies on even mass tin isotopes from doubly-magic 132 to stable 124Sn. Work supported in part by the U.S. Department of Energy and National Science Foundation.

  18. Predicting the capture rate in the Sun from a direct detection signal independently of the astrophysics

    NASA Astrophysics Data System (ADS)

    Herrero-Garcia, Juan

    2016-05-01

    The goal of the works on which this talk is based is to relate a direct detection signal with neutrino limits from the Sun independently of the astrophysics. In order to achieve this we derive a halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal, with which one can set upper limits on the branching ratios into different channels from the absence of a high-energy neutrino flux in neutrino observatories. We also extend this bound to the case of inelastic scattering, both endothermic and exothermic. From two inelastic signals we show how the dark matter mass, the mass difference of the states and the couplings to neutrons and protons can be obtained. Furthermore, one can also pin down the exothermic/endothermic nature of the scattering, and therefore a precise lower bound on the solar capture rate is predicted. We also discuss isospin violation and uncertainties due to form factors.

  19. Evidence for correlations between fluctuations in 54Mn decay rates and solar storms

    NASA Astrophysics Data System (ADS)

    Mohsinally, T.; Fancher, S.; Czerny, M.; Fischbach, E.; Gruenwald, J. T.; Heim, J.; Jenkins, J. H.; Nistor, J.; O'Keefe, D.

    2016-02-01

    Following recent indications that several radioactive isotopes show fluctuating decay rates which may be influenced by solar activity, we present findings from a 2 year period of data collection on 54Mn. Measurements were recorded hourly from a 1 μCi sample of 54Mn monitored from January 2010-December 2011. A series of signal-detection algorithms determine regions of statistically significant fluctuations in decay behaviour from the expected exponential form. The 239 decay flags identified during this interval were compared to daily distributions of multiple solar indices, generated by NOAA, which are associated with heightened solar activity. The indices were filtered to provide a list of the 413 strongest events during a coincident period. We find that 49% of the strongest solar events are preceded by at least 1 decay flag within a 48 h interval, and 37% of decay flags are followed by a reported solar event within 48 h. These results are significant at the 0.9σ and 2.8σ levels respectively, based on a comparison to results obtained from a shuffle test, in which the decay measurements were randomly shuffled in time 10,000 times. We also present results from a simulation combining constructed data reflecting 10 sites which compared and filtered decay flags generated from all sites. The results indicate a potential 35% reduction in the false positive rate in going from 1 to 10 sites. By implication, the improved statistics attest to the benefit of analysing data from a larger number of geographically distributed sites in parallel.

  20. Rates for neutron-capture reactions on tungsten isotopes in iron meteorites. [Abstract only

    NASA Technical Reports Server (NTRS)

    Masarik, J.; Reedy, R. C.

    1994-01-01

    High-precision W isotopic analyses by Harper and Jacobsen indicate the W-182/W-183 ratio in the Toluca iron meteorite is shifted by -(3.0 +/- 0.9) x 10(exp -4) relative to a terrestrial standard. Possible causes of this shift are neutron-capture reactions on W during Toluca's approximately 600-Ma exposure to cosmic ray particles or radiogenic growth of W-182 from 9-Ma Hf-182 in the silicate portion of the Earth after removal of W to the Earth's core. Calculations for the rates of neutron-capture reactions on W isotopes were done to study the first possibility. The LAHET Code System (LCS) which consists of the Los Alamos High Energy Transport (LAHET) code and the Monte Carlo N-Particle(MCNP) transport code was used to numerically simulate the irradiation of the Toluca iron meteorite by galactic-cosmic-ray (GCR) particles and to calculate the rates of W(n, gamma) reactions. Toluca was modeled as a 3.9-m-radius sphere with the composition of a typical IA iron meteorite. The incident GCR protons and their interactions were modeled with LAHET, which also handled the interactions of neutrons with energies above 20 MeV. The rates for the capture of neutrons by W-182, W-183, and W-186 were calculated using the detailed library of (n, gamma) cross sections in MCNP. For this study of the possible effect of W(n, gamma) reactions on W isotope systematics, we consider the peak rates. The calculated maximum change in the normalized W-182/W-183 ratio due to neutron-capture reactions cannot account for more than 25% of the mass 182 deficit observed in Toluca W.

  1. Universal behavior of the spin-echo decay rate in La2CuO4

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey V.; Sachdev, Subir; Sokol, Alexander

    1994-04-01

    We present a theoretical expression for the spin-echo decay rate 1/T2G in the quantum-critical regime of square-lattice quantum antiferromagnets. Our results are in good agreement with recent experimental data by Imai et al. [Phys. Rev. Lett. 71, 1254 (1993)] for La2CuO4.

  2. False vacuum transitions —Analytical solutions and decay rate values

    NASA Astrophysics Data System (ADS)

    Correa, R. A. C.; Moraes, P. H. R. S.; da Rocha, Roldão

    2015-08-01

    In this work we show a class of oscillating configurations for the evolution of the domain walls in Euclidean space. The solutions are obtained analytically. Phase transitions are achieved from the associated fluctuation determinant, by the decay rates of the false vacuum.

  3. Estimate Of The Decay Rate Constant of Hydrogen Sulfide Generation From Landfilled Drywall

    EPA Science Inventory

    Research was conducted to investigate the impact of particle size on H2S gas emissions and estimate a decay rate constant for H2S gas generation from the anaerobic decomposition of drywall. Three different particle sizes of regular drywall and one particle size of paperless drywa...

  4. Conserved Non-Coding Sequences are Associated with Rates of mRNA Decay in Arabidopsis

    PubMed Central

    Spangler, Jacob B.; Feltus, Frank Alex

    2013-01-01

    Steady-state mRNA levels are tightly regulated through a combination of transcriptional and post-transcriptional control mechanisms. The discovery of cis-acting DNA elements that encode these control mechanisms is of high importance. We have investigated the influence of conserved non-coding sequences (CNSs), DNA patterns retained after an ancient whole genome duplication event, on the breadth of gene expression and the rates of mRNA decay in Arabidopsis thaliana. The absence of CNSs near α duplicate genes was associated with a decrease in breadth of gene expression and slower mRNA decay rates while the presence CNSs near α duplicates was associated with an increase in breadth of gene expression and faster mRNA decay rates. The observed difference in mRNA decay rate was fastest in genes with CNSs in both non-transcribed and transcribed regions, albeit through an unknown mechanism. This study supports the notion that some Arabidopsis CNSs regulate the steady-state mRNA levels through post-transcriptional control mechanisms and that CNSs also play a role in controlling the breadth of gene expression. PMID:23675377

  5. β+ Gamow-Teller transition strengths from 46Ti and stellar electron-capture rates.

    PubMed

    Noji, S; Zegers, R G T; Austin, Sam M; Baugher, T; Bazin, D; Brown, B A; Campbell, C M; Cole, A L; Doster, H J; Gade, A; Guess, C J; Gupta, S; Hitt, G W; Langer, C; Lipschutz, S; Lunderberg, E; Meharchand, R; Meisel, Z; Perdikakis, G; Pereira, J; Recchia, F; Schatz, H; Scott, M; Stroberg, S R; Sullivan, C; Valdez, L; Walz, C; Weisshaar, D; Williams, S J; Wimmer, K

    2014-06-27

    The Gamow-Teller strength in the β(+) direction to (46)Sc was extracted via the (46)Ti(t,(3)He + γ) reaction at 115  MeV/u. The γ-ray coincidences served to precisely measure the very weak Gamow-Teller transition to a final state at 991 keV. Although this transition is weak, it is crucial for accurately estimating electron-capture rates in astrophysical scenarios with relatively low stellar densities and temperatures, such as presupernova stellar evolution. Shell-model calculations with different effective interactions in the pf shell-model space do not reproduce the experimental Gamow-Teller strengths, which is likely due to sd-shell admixtures. Calculations in the quasiparticle random phase approximation that are often used in astrophysical simulations also fail to reproduce the experimental Gamow-Teller strength distribution, leading to strongly overestimated electron-capture rates. Because reliable theoretical predictions of Gamow-Teller strengths are important for providing astrophysical electron-capture reaction rates for a broad set of nuclei in the lower pf shell, we conclude that further theoretical improvements are required to match astrophysical needs. PMID:25014806

  6. The rate of decay of fresh fission products from a nuclear reactor

    NASA Astrophysics Data System (ADS)

    Dolan, David J.

    Determining the rate of decay of fresh fission products from a nuclear reactor is complex because of the number of isotopes involved, different types of decay, half-lives of the isotopes, and some isotopes decay into other radioactive isotopes. Traditionally, a simplified rule of 7s and 10s is used to determine the dose rate from nuclear weapons and can be to estimate the dose rate from fresh fission products of a nuclear reactor. An experiment was designed to determine the dose rate with respect to time from fresh fission products of a nuclear reactor. The experiment exposed 0.5 grams of unenriched Uranium to a fast and thermal neutron flux from a TRIGA Research Reactor (Lakewood, CO) for ten minutes. The dose rate from the fission products was measured by four Mirion DMC 2000XB electronic personal dosimeters over a period of six days. The resulting dose rate following a rule of 10s: the dose rate of fresh fission products from a nuclear reactor decreases by a factor of 10 for every 10 units of time.

  7. Invariance of decay rate with respect to boundary conditions in thermoelastic Timoshenko systems

    NASA Astrophysics Data System (ADS)

    Alves, M. S.; Jorge Silva, M. A.; Ma, T. F.; Muñoz Rivera, J. E.

    2016-06-01

    This paper is mainly concerned with the polynomial stability of a thermoelastic Timoshenko system recently introduced by Almeida Júnior et al. (Z Angew Math Phys 65(6):1233-1249, 2014) that proved, in the general case when equal wave speeds are not assumed, different polynomial decay rates depending on the boundary conditions, namely, optimal rate {t^{-1/2}} for mixed Dirichlet-Neumann boundary condition and rate {t^{-1/4}} for full Dirichlet boundary condition. Here, our main achievement is to prove the same polynomial decay rate {t^{-1/2}} (corresponding to the optimal one) independently of the boundary conditions, which improves the existing literature on the subject. As a complementary result, we also prove that the system is exponentially stable under equal wave speeds assumption. The technique employed here can probably be applied to other kind of thermoelastic systems.

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

    SciTech Connect

    Banks, Thomas Ira

    2007-07-10

    This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between the mu- disappearance rate in hydrogen--as determinedfrom data collected in the experiment's first physics run in fall2004--and the world averagefor the mu+ decay rate. After combining theresults of my analysis with the results from another independent analysisof the 2004 data, the muon capture rate from the hyperfine singlet groundstate of the mu-p atom is found to be Lambda_S = 725.0 +- 17.4 1/s, fromwhich the induced pseudoscalar coupling of the nucleon, gP(q2 = -0.88m2mu)= 7.3 +- 1.1, is extracted. This result for gP is consistent withtheoretical predictions that are based on the approximate chiral symmetryof QCD.

  9. Configuration splitting and gamma-decay transition rates in the two-group shell model

    SciTech Connect

    Isakov, V. I.

    2015-09-15

    Expressions for reduced gamma-decay transition rates were obtained on the basis of the twogroup configuration model for the case of transitions between particles belonging to identical groups of nucleons. In practical applications, the present treatment is the most appropriate for describing decays for odd–odd nuclei in the vicinity of magic nuclei or for nuclei where the corresponding subshells stand out in energy. Also, a simple approximation is applicable to describing configuration splitting in those cases. The present calculations were performed for nuclei whose mass numbers are close to A ∼ 90, including N = 51 odd—odd isotones.

  10. Measurement of the decay rate of the SiH feature as a function of temperature

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A., III; Kraus, George F.

    1994-01-01

    We have previously suggested that the SiH fundamental stretch could serve as a diagnostic indicator of the oxidation state of silicate surfaces exposed to the solar wind for prolonged periods. We have now measured the primary decay rate of SiH in vacuo as a function of temperature and find that the primary rate constant for the decay can be characterized by the following equation: k(min(exp -1)) approximately equals 0.186 exp(-9/RT) min(exp -1), where R = 2 x 10(exp -3) kcal deg(exp -1) mole(exp -1). This means that the half-life for the decay of the SiH feature at room temperature is approximately 20 yrs, whereas the half-life at a peak lunar regolith temperature of approximately 500K would be only approximately 20 days. At the somewhat lower temperature of approximately 400K the half-life for the decay is on the order of 200 days. The rate of loss of SiH as a function of temperature provides an upper limit to the quantity of H implanted by the solar wind which can be retained by a silicate grain in a planetary regolith. This will be discussed in more detail here.

  11. Measurement of the solar neutrino capture rate with gallium metal, part III

    SciTech Connect

    Elliott, Steven Ray

    2008-01-01

    The Russian-American experiment SAGE began to measure the solar neutrino capture rate with a target of gallium metal in December 1989. Measurements have continued with only a few brief interruptions since that time. In this article we present the experimental improvements in SAGE since its last published data summary in December 2001. Assuming the solar neutrino production rate was constant during the period of data collection, combined analysis of 168 extractions through December 2007 gives a capture rate of solar neutrinos with energy more than 233 keY of 65.4{sup +3.1}{sub 3.0} (stat) {sup +2.6}{sub -2.8} (syst) SNU. The weighted average of the results of all three Ga solar neUlrino experiments, SAGE, Gallex, and GNO, is now 66.1 {+-} 3.1 SNU, where statistical and systematic uncertainties have been combined in quadrature. During the recent period of data collection a new test of SAGE was made with a reactor-produced {sup 37}Ar neutrino source. The ratio of observed to calculated rates in this experiment, combined with the measured rates in the three prior {sup 51}Cr neutrino-source experiments with Ga, is 0.88 {+-} 0.05. A probable explanation for this low result is that the cross section for neutrino capture by the two lowest-lying excited states in {sup 71}Ge has been overestimated. If we assume these cross sections are zero, then the standard solar model including neutrino oscillations predicts a total capture rate in Ga in the range of 63--67 SNU with an uncertainly of about 5%, in good agreement with experiment. We derive the current value of the pp neutrino flux produced in the Sun to be {phi}{sup {circle_dot}}{sub pp} = (6.1 {+-} 0.8) x 10{sup 10}/(cm{sup 2} s), which agrees well with the flux predicted by the standard solar model. Finally, we make several tests and show that the data are consistent with the assumption that the solar neutrino production rate is constant in time.

  12. Beta-decay rate and beta-delayed neutron emission probability of improved gross theory

    NASA Astrophysics Data System (ADS)

    Koura, Hiroyuki

    2014-09-01

    A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for unmeasured nuclei are adopted from the KTUY nuclear mass formula, which is based on the spherical-basis method. Considering the properties of the integrated Fermi function, we can roughly categorized energy region of excited-state of a daughter nucleus into three regions: a highly-excited energy region, which fully affect a delayed neutron probability, a middle energy region, which is estimated to contribute the decay heat, and a region neighboring the ground-state, which determines the beta-decay rate. Some results will be given in the presentation. A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for

  13. Determining astrophysical three-body radiative capture reaction rates from inclusive Coulomb break-up measurements

    NASA Astrophysics Data System (ADS)

    Casal, J.; Rodríguez-Gallardo, M.; Arias, J. M.; Gómez-Camacho, J.

    2016-04-01

    A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of B (E 1 ) distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to 11Li (9Li+n +n ) and 6He (4He+n +n ) three-body systems for which some data exist.

  14. Stellar electron-capture rates calculated with the finite-temperature relativistic random-phase approximation

    SciTech Connect

    Niu, Y. F.; Paar, N.; Vretenar, D.; Meng, J.

    2011-04-15

    We introduce a self-consistent microscopic theoretical framework for modeling the process of electron capture on nuclei in stellar environment, based on relativistic energy density functionals. The finite-temperature relativistic mean-field model is used to calculate the single-nucleon basis and the occupation factors in a target nucleus, and J{sup {pi}}=0{sup {+-}}, 1{sup {+-}}, and 2{sup {+-}} charge-exchange transitions are described by the self-consistent finite-temperature relativistic random-phase approximation. Cross sections and rates are calculated for electron capture on {sup 54,56}Fe and {sup 76,78}Ge in stellar environment, and results compared with predictions of similar and complementary model calculations.

  15. Determination of phonon decay rate in p-type silicon under Fano resonance by measurement of coherent phonons

    NASA Astrophysics Data System (ADS)

    Kato, Keiko; Oguri, Katsuya; Sanada, Haruki; Tawara, Takehiko; Sogawa, Tetsuomi; Gotoh, Hideki

    2015-09-01

    We determine phonon decay rate by measuring the temperature dependence of coherent phonons in p-type Si under Fano resonance, where there is interference between the continuum and discrete states. As the temperature decreases, the decay rate of coherent phonons decreases, whereas that evaluated from the Raman linewidth increases. The former follows the anharmonic decay model, whereas the latter does not. The different temperature dependences of the phonon decay rate of the two methods originate from the way that the continuum state, which originates from the Fano resonance, modifies the time- and frequency-domain spectra. The observation of coherent phonons is useful for evaluating the phonon decay rate free from the interaction with the continuum state and clarifies that the anharmonic decay is dominant in p-type Si even under Fano resonance.

  16. ASSESSMENT OF THE RATES OF INJURY AND MORTALITY IN WATERFOWL CAPTURED WITH FIVE METHODS OF CAPTURE AND TECHNIQUES FOR MINIMIZING RISKS.

    PubMed

    O'Brien, Michelle F; Lee, Rebecca; Cromie, Ruth; Brown, Martin J

    2016-04-01

    Swan pipes, duck decoys, cage traps, cannon netting, and roundups are widely used to capture waterfowl in order to monitor populations. These methods are often regulated in countries with national ringing or banding programs and are considered to be safe, and thus justifiable given the benefits to conservation. However, few published studies have addressed how frequently injuries and mortalities occur, or the nature of any injuries. In the present study, rates of mortality and injury during captures with the use of these methods carried out by the Wildfowl & Wetlands Trust as part of conservation programs were assessed. The total rate of injury (including mild dermal abrasions) was 0.42% across all species groups, whereas total mortality was 0.1% across all capture methods. Incidence of injury varied among species groups (ducks, geese, swans, and rails), with some, for example, dabbling ducks, at greater risk than others. We also describe techniques used before, during, and after a capture to reduce stress and injury in captured waterfowl. Projects using these or other capture methods should monitor and publish their performance to allow sharing of experience and to reduce risks further. PMID:26845303

  17. Estimating the Esophagus Cancer Incidence Rate in Ardabil, Iran: A Capture-Recapture Method

    PubMed Central

    Khodadost, Mahmoud; Yavari, Parvin; Khodadost, Behnam; Babaei, Masoud; Sarvi, Fatemeh; Khatibi, Seyed Reza; Barzegari, Saeed

    2016-01-01

    Background: Accurate cancer registry and awareness of cancer incidence rate is essential in order to define strategies for cancer prevention and control programs. Capture-recapture methods have been recommended for reducing bias and increase the accuracy of cancer incidence estimation. Objectives: This study aimed to estimate the esophagus cancer incidence by capture-recapture method based on Ardabil population-based cancer registry data. Patients and Methods: Total new cases of esophagus cancer reported by three sources of pathology reports, medical records, and death certificates to Ardabil province cancer registry center in 2006 and 2008 were enrolled in the study. All duplicated cases between three sources were identified and removed using Excel software. Some characteristics such as name, surname, father’s name, date of birth and ICD codes related to their cancer type were used for data linkage and finding the common cases among three sources. The incidence rate per 100,000 was estimated based on capture-recapture method using the log-linear models. We used BIC, G2 and AIC statistics to select the best-fit model. Results: After removing duplicates, total 471 new cases of esophagus cancer were reported from three sources. The model with linkage between pathology reports, medical record sources and independence with the death certificates source was the best fitted model. The reported incidence rate for the years 2006 and 2008 was 18.77 and 18.51 per 100,000, respectively. In log-linear analysis, the estimated incidence rate for the years 2006 and 2008 was 49.71 and 53.87 per 100,000 populations, respectively. Conclusions: Based on the obtained results, it can be concluded that none of the sources of pathology reports, death certificates and medical records individually or collectively were fully covered the incidence cases of esophagus cancer and need to apply some changes in data abstracting and case finding.

  18. The role of wall confinement on the decay rate of an initially isotropic turbulent field

    NASA Astrophysics Data System (ADS)

    Dowling, David R.; Movahed, Pooya; Johnsen, Eric

    2014-11-01

    The problem of freely decaying isotropic turbulence has been the subject of intensive research during the past few decades due to its importance for modeling purposes. While isotropy and periodic boundary conditions assumptions simplify the analysis, large-scale anisotropy (e.g., caused by rotation, shear, acceleration or walls) is in practice present in most turbulent flows and affects flow dynamics across different scales, as well as the kinetic energy decay. We investigate the role of wall confinement and viscous dissipation on the decay rate of an initially isotropic field for confining volumes of different aspect ratios. We first generate an isotropic velocity field in a cube with periodic boundary conditions. Next, using this field, we change the boundary conditions to no-slip walls on all sides. These walls restrict the initial field to a confined geometry and also provide an additional viscous dissipation mechanism. The problem is considered for confining volumes of different aspect ratios by adjusting the initial field. The change in confining volume introduces an additional length scale to the problem. Direct numerical simulation of the proposed set-up is used to verify the scaling arguments for the decay rate of kinetic energy. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number ACI-1053575.

  19. Polynomial decay rate of a thermoelastic Mindlin-Timoshenko plate model with Dirichlet boundary conditions

    NASA Astrophysics Data System (ADS)

    Grobbelaar-Van Dalsen, Marié

    2015-02-01

    In this article, we are concerned with the polynomial stabilization of a two-dimensional thermoelastic Mindlin-Timoshenko plate model with no mechanical damping. The model is subject to Dirichlet boundary conditions on the elastic as well as the thermal variables. The work complements our earlier work in Grobbelaar-Van Dalsen (Z Angew Math Phys 64:1305-1325, 2013) on the polynomial stabilization of a Mindlin-Timoshenko model in a radially symmetric domain under Dirichlet boundary conditions on the displacement and thermal variables and free boundary conditions on the shear angle variables. In particular, our aim is to investigate the effect of the Dirichlet boundary conditions on all the variables on the polynomial decay rate of the model. By once more applying a frequency domain method in which we make critical use of an inequality for the trace of Sobolev functions on the boundary of a bounded, open connected set we show that the decay is slower than in the model considered in the cited work. A comparison of our result with our polynomial decay result for a magnetoelastic Mindlin-Timoshenko model subject to Dirichlet boundary conditions on the elastic variables in Grobbelaar-Van Dalsen (Z Angew Math Phys 63:1047-1065, 2012) also indicates a correlation between the robustness of the coupling between parabolic and hyperbolic dynamics and the polynomial decay rate in the two models.

  20. Comparing the effectiveness of heat rate improvements in different coal-fired power plants utilizing carbon dioxide capture

    NASA Astrophysics Data System (ADS)

    Walsh, Martin Jeremy

    New Congressional legislation may soon require coal-fired power generators to pay for their CO2 emissions and capture a minimum level of their CO2 output. Aminebased CO2 capture systems offer plants the most technically proven and commercially feasible option for CO2 capture at this time. However, these systems require a large amount of heat and power to operate. As a result, amine-based CO2 capture systems significantly reduce the net power of any units in which they are installed. The Energy Research Center has compiled a list of heat rate improvements that plant operators may implement before installing a CO2 capture system. The goal of these improvements is to upgrade the performance of existing units and partially offset the negative effects of adding a CO2 capture system. Analyses were performed in Aspen Plus to determine the effectiveness of these heat rate improvements in preserving the net power and net unit heat rate (NUHR) of four different power generator units. For the units firing high-moisture sub-bituminous coal, the heat rate improvements reduced NUHR by an average of 13.69% across a CO 2 capture level range of 50% to 90%. For the units firing bituminous coal across the same CO2 capture range, the heat rate improvements reduced NUHR by an average of 12.30%. Regardless of the units' coal or steam turbine cycle type, the heat rate improvements preserved 9.7% to 11.0% of each unit's net power across the same CO2 capture range. In general, the heat rate improvements were found to be most effective in improving the performance of units firing high-moisture sub-bituminous. The effect of the CO2 capture system on these units and the reasons for the improvements' greater effectiveness in them are described in this thesis.

  1. Correlation Between Decay Rate and Amplitude of Solar Cycles as Revealed from Observations and Dynamo Theory

    NASA Astrophysics Data System (ADS)

    Hazra, Gopal; Karak, Bidya Binay; Banerjee, Dipankar; Choudhuri, Arnab Rai

    2015-06-01

    Using different proxies of solar activity, we have studied the following features of the solar cycle: i) The linear correlation between the amplitude of cycle and its decay rate, ii) the linear correlation between the amplitude of cycle and the decay rate of cycle , and iii) the anti-correlation between the amplitude of cycle and the period of cycle . Features ii) and iii) are very useful because they provide precursors for future cycles. We have reproduced these features using a flux-transport dynamo model with stochastic fluctuations in the Babcock-Leighton effect and in the meridional circulation. Only when we introduce fluctuations in meridional circulation, are we able to reproduce different observed features of the solar cycle. We discuss the possible reasons for these correlations.

  2. Optimal decay rates of classical solutions for the full compressible MHD equations

    NASA Astrophysics Data System (ADS)

    Gao, Jincheng; Tao, Qiang; Yao, Zheng-an

    2016-04-01

    In this paper, we are concerned with optimal decay rates for higher-order spatial derivatives of classical solutions to the full compressible MHD equations in three-dimensional whole space. If the initial perturbation is small in {H^3}-norm and bounded in {L^q(qin [1, 6/5 ))}-norm, we apply the Fourier splitting method by Schonbek (Arch Ration Mech Anal 88:209-222, 1985) to establish optimal decay rates for the second-order spatial derivatives of solutions and the third-order spatial derivatives of magnetic field in {L^2}-norm. These results improve the work of Pu and Guo (Z Angew Math Phys 64:519-538, 2013).

  3. Initial cooperative decay rate and cooperative Lamb shift of resonant atoms in an infinite cylindrical geometry

    SciTech Connect

    Friedberg, Richard; Manassah, Jamal T.

    2011-08-15

    We obtain in both the scalar and vector photon models the analytical expressions for the initial cooperative decay rate and the cooperative Lamb shift for an ensemble of resonant atoms distributed uniformly in an infinite cylindrical geometry for the case that the initial state of the system is prepared in a phased state modulated in the direction of the cylindrical axis. We find that qualitatively the scalar and vector theories give different results.

  4. General decay rate estimates for viscoelastic wave equation with Balakrishnan-Taylor damping

    NASA Astrophysics Data System (ADS)

    Ha, Tae Gab

    2016-04-01

    In this paper, we consider the viscoelastic wave equation with Balakrishnan-Taylor damping. This work is devoted to prove uniform decay rates of the energy without imposing any restrictive growth assumption on the damping term and weakening the usual assumptions on the relaxation function. Our estimate depends both on the behavior of the damping term near zero and on behavior of the relaxation function at infinity.

  5. Absorption cross-section and decay rate of rotating linear dilaton black holes

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Aslan, O. A.

    2016-02-01

    We analytically study the scalar perturbation of non-asymptotically flat (NAF) rotating linear dilaton black holes (RLDBHs) in 4-dimensions. We show that both radial and angular wave equations can be solved in terms of the hypergeometric functions. The exact greybody factor (GF), the absorption cross-section (ACS), and the decay rate (DR) for the massless scalar waves are computed for these black holes (BHs). The results obtained for ACS and DR are discussed through graphs.

  6. Peculiarities of parabolic-barrier penetrability and thermal decay rate with the quantum diffusion approach

    SciTech Connect

    Kuzyakin, R. A.; Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2011-06-15

    With the quantum diffusion approach, the passing probability through the parabolic barrier is examined in the limit of linear coupling in the momentum between the collective subsystem and environment. The dependencies of the penetrability on time, energy, and the coupling strength between the interacting subsystems are studied. The quasistationary thermal decay rate from a metastable state is considered in the cases of linear couplings both in the momentum and in the coordinate.

  7. Direct Measurement of the Unimolecular Decay Rate of Criegee Intermediates to OH Products

    NASA Astrophysics Data System (ADS)

    Liu, Fang; Fang, Yi; Klippenstein, Stephen; McCoy, Anne; Lester, Marsha

    Ozonolysis of alkenes is an important non-photolytic source of OH radicals in the troposphere. The production of OH radicals proceeds though formation and unimolecular decay of Criegee intermediates such as syn-CH3CHOO and (CH3)2COO. These alkyl-substituted Criegee intermediates can undergo a 1,4-H transfer reaction to form an energized vinyl hydroperoxide species, which breaks apart to OH and vinoxy products. Recently, this laboratory used IR excitation in the C-H stretch overtone region to initiate the unimolecular decay of syn-CH3CHOO and (CH3)2COO Criegee intermediates, leading to OH formation. Here, direct time-domain measurements are performed to observe the rate of appearance of OH products under collision-free conditions utilizing UV laser-induced fluorescence for detection. The experimental rates are in excellent agreement with statistical RRKM calculations using barrier heights predicted from high-level electronic structure calculations. Accurate determination of the rates and barrier heights for unimolecular decay of Criegee intermediates is essential for modeling the kinetics of alkene ozonolysis reactions, a significant OH radical source in atmospheric chemistry, as well as the steady-state concentration of Criegee intermediates in the atmosphere. This research was supported through the National Science Foundation under grant CHE-1362835.

  8. CONCERNING THE PHASES OF THE ANNUAL VARIATIONS OF NUCLEAR DECAY RATES

    SciTech Connect

    Sturrock, P. A.; Buncher, J. B.; Fischbach, E.; Jenkins, J. H.; Mattes, J. J.; Javorsek, D. II

    2011-08-20

    Recent analyses of data sets acquired at the Brookhaven National Laboratory and at the Physikalisch-Technische Bundesanstalt both show evidence of pronounced annual variations, suggestive of a solar influence. However, the phases of decay-rate maxima do not correspond precisely to the phase of minimum Sun-Earth distance, as might then be expected. We here examine the hypothesis that decay rates are influenced by an unknown solar radiation, but that the intensity of the radiation is influenced not only by the variation in Sun-Earth distance, but also by a possible north-south asymmetry in the solar emission mechanism. We find that this can lead to phases of decay-rate maxima in the range 0-0.183 or 0.683-1 (September 6 to March 8) but that, according to this hypothesis, phases in the range of 0.183-0.683 (March 8 to September 6) are 'forbidden'. We find that phases of the three data sets analyzed here fall in the allowed range.

  9. Radiative decay rate of excitons in square quantum wells: Microscopic modeling and experiment

    NASA Astrophysics Data System (ADS)

    Khramtsov, E. S.; Belov, P. A.; Grigoryev, P. S.; Ignatiev, I. V.; Verbin, S. Yu.; Efimov, Yu. P.; Eliseev, S. A.; Lovtcius, V. A.; Petrov, V. V.; Yakovlev, S. L.

    2016-05-01

    The binding energy and the corresponding wave function of excitons in GaAs-based finite square quantum wells (QWs) are calculated by the direct numerical solution of the three-dimensional Schrödinger equation. The precise results for the lowest exciton state are obtained by the Hamiltonian discretization using the high-order finite-difference scheme. The microscopic calculations are compared with the results obtained by the standard variational approach. The exciton binding energies found by two methods coincide within 0.1 meV for the wide range of QW widths. The radiative decay rate is calculated for QWs of various widths using the exciton wave functions obtained by direct and variational methods. The radiative decay rates are confronted with the experimental data measured for high-quality GaAs/AlGaAs and InGaAs/GaAs QW heterostructures grown by molecular beam epitaxy. The calculated and measured values are in good agreement, though slight differences with earlier calculations of the radiative decay rate are observed.

  10. Photonic effects on the radiative decay rate and luminescence quantum yield of doped nanocrystals.

    PubMed

    Senden, Tim; Rabouw, Freddy T; Meijerink, Andries

    2015-02-24

    Nanocrystals (NCs) doped with luminescent ions form an emerging class of materials. In contrast to excitonic transitions in semiconductor NCs, the optical transitions are localized and not affected by quantum confinement. The radiative decay rates of the dopant emission in NCs are nevertheless different from their bulk analogues due to photonic effects, and also the luminescence quantum yield (QY, important for applications) is affected. In the past, different theoretical models have been proposed to describe the photonic effects for dopant emission in NCs, with little experimental validation. In this work we investigate the photonic effects on the radiative decay rate of luminescent doped NCs using 4 nm LaPO4 NCs doped with Ce(3+) or Tb(3+) ions in different refractive index solvents and bulk crystals. We demonstrate that the measured influence of the refractive index on the radiative decay rate of the Ce(3+) emission, having near unity QY, is in excellent agreement with the theoretical nanocrystal-cavity model. Furthermore, we show how the nanocrystal-cavity model can be used to quantify the nonunity QY of Tb(3+)-doped LaPO4 NCs and demonstrate that, as a general rule, the QY is higher in media with higher refractive index. PMID:25584627

  11. β -decay rates of Cs-131121 in the microscopic interacting boson-fermion model

    NASA Astrophysics Data System (ADS)

    Mardones, E.; Barea, J.; Alonso, C. E.; Arias, J. M.

    2016-03-01

    β -decay rates of Cs-131121 have been calculated in the framework of the neutron-proton interacting boson-fermion model (IBFM-2). For odd-A nuclei, the decay operator can be written in a relatively simple form in terms of the one-nucleon transfer operator. Previous studies of β decay in IBFM-2 were based on a transfer operator obtained by using the number operator approximation (NOA). In this work a new form of the one-nucleon transfer operator, derived microscopically without the NOA approximation, is used. The results from both approaches are compared and show that the deviation from experimental data is reduced without using the NOA approximation. Indications about the renormalization of the Fermi and Gamow-Teller matrix elements are discussed. This is a further step toward a more complete description of low-lying states in medium and heavy nuclei which is necessary to compute reliable matrix elements in studies of current active interest such as double-β decay or neutrino absorption experiments.

  12. Rate-dependent interface capture beyond the coffee-ring effect

    NASA Astrophysics Data System (ADS)

    Li, Yanan; Yang, Qiang; Li, Mingzhu; Song, Yanlin

    2016-04-01

    The mechanism of droplet drying is a widely concerned fundamental issue since controlling the deposition morphology of droplet has significant influence on printing, biology pattern, self-assembling and other solution-based devices fabrication. Here we reveal a striking different kinetics-controlled deposition regime beyond the ubiquitous coffee-ring effect that suspended particles tend to kinetically accumulate at the air-liquid interface and deposit uniformly. As the interface shrinkage rate exceeds the particle average diffusion rate, particles in vertical evaporation flow will be captured by the descending surface, producing surface particle jam and forming viscous quasi-solid layer, which dramatically prevents the trapped particles from being transported to drop edge and results in uniform deposition. This simple, robust drying regime will provide a versatile strategy to control the droplet deposition morphology, and a novel direction of interface assembling for fabricating superlattices and high quality photonic crystal patterns.

  13. Rate-dependent interface capture beyond the coffee-ring effect.

    PubMed

    Li, Yanan; Yang, Qiang; Li, Mingzhu; Song, Yanlin

    2016-01-01

    The mechanism of droplet drying is a widely concerned fundamental issue since controlling the deposition morphology of droplet has significant influence on printing, biology pattern, self-assembling and other solution-based devices fabrication. Here we reveal a striking different kinetics-controlled deposition regime beyond the ubiquitous coffee-ring effect that suspended particles tend to kinetically accumulate at the air-liquid interface and deposit uniformly. As the interface shrinkage rate exceeds the particle average diffusion rate, particles in vertical evaporation flow will be captured by the descending surface, producing surface particle jam and forming viscous quasi-solid layer, which dramatically prevents the trapped particles from being transported to drop edge and results in uniform deposition. This simple, robust drying regime will provide a versatile strategy to control the droplet deposition morphology, and a novel direction of interface assembling for fabricating superlattices and high quality photonic crystal patterns. PMID:27090820

  14. Rate-dependent interface capture beyond the coffee-ring effect

    PubMed Central

    Li, Yanan; Yang, Qiang; Li, Mingzhu; Song, Yanlin

    2016-01-01

    The mechanism of droplet drying is a widely concerned fundamental issue since controlling the deposition morphology of droplet has significant influence on printing, biology pattern, self-assembling and other solution-based devices fabrication. Here we reveal a striking different kinetics-controlled deposition regime beyond the ubiquitous coffee-ring effect that suspended particles tend to kinetically accumulate at the air-liquid interface and deposit uniformly. As the interface shrinkage rate exceeds the particle average diffusion rate, particles in vertical evaporation flow will be captured by the descending surface, producing surface particle jam and forming viscous quasi-solid layer, which dramatically prevents the trapped particles from being transported to drop edge and results in uniform deposition. This simple, robust drying regime will provide a versatile strategy to control the droplet deposition morphology, and a novel direction of interface assembling for fabricating superlattices and high quality photonic crystal patterns. PMID:27090820

  15. Age-specificity of black-capped chickadee survival rates: Analysis of capture-recapture data

    USGS Publications Warehouse

    Loery, G.; Pollock, K.H.; Nichols, J.D.; Hines, J.E.

    1987-01-01

    The ornithological literature indicates a widespread belief in two generalizations about the age-specificity of avian survival rates: (1) survival rates of young birds for some period following fledging are lower than those of adults, and (2) after reaching adulthood survival rates are constant for birds of all ages. There is a growing body of evidence in support of the first generalization, although little is known about how long the survival difference between young and adults lasts. This latter question can be addressed with capture-recapture or band recovery studies based on birds marked in the winter, but the inability to determine age in many species during winter has prevented the use of standard methods. There is very little evidence supporting the second generalization, and we are in need of methods and actual analyses that address this question. In the present paper we restate the two generalizations as hypotheses and test them using data from a wintering Black-capped Chickadee (Parus atricapillus) population in Connecticut, which has been studied by Loery for 26 yr. We use a cohort-based Jolly-Seber approach, which should be useful in other investigations of this nature. We found strong evidence of lower survival rates in 1st-yr birds than in adults, but could not determine whether this was the result of higher mortality rates, higher emigration rates, or a combination of the two. We also found evidence that survival rates of adult birds were not constant with age but decreased at a rate of ? 3.5%/yr. As adult birds are very faithful to their wintering areas, we believe that almost all this decrease can be attributed to an increase in mortality with age. Simulation results suggest that heterogeneity of capture probabilities could not explain the magnitude of the decrease in survival with age. Age-dependent tag loss is also discussed as an alternative explanation, but is dismissed as very unlikely in this situation. This analysis thus provides some of the

  16. The OXYGEN-15(ALPHA, GAMMA)NEON-19 Reaction Rate and the Rapid-Proton Capture Process

    NASA Astrophysics Data System (ADS)

    Magnus, Paul Vogt

    The energetics and the rates of the various nuclear reaction chains active in stars play a critical role in the stars' evolution and in the isotopic abundances resulting from this nucleosynthesis. One can therefore gain information about the structure and evolution of stars by examining these nuclear reaction chains and the resulting elemental and isotopic abundances. The abundances of a number of isotopes (e.g., 13C and ^ {15}N) point to the importance of explosive hydrogen burning which takes place on time scales which are short compared to the relevant beta-decay lifetimes. Explosive hydrogen burning is expected to occur at high temperatures (rm T>2times10^8K) in many astrophysical environments such as super-massive stars, accreting neutron stars, red giants with neutron star cores, novae, and supernovae. In these environments it is usually assumed that hydrogen burning occurs via the Hot-CNO (HCNO) cycle which is responsible for the observed abundance of 15N. At sufficiently high temperatures, however, the ^ {15}O(alpha,gamma)^{19 }Ne reaction can break the HCNO cycle and initiate a reaction chain called the rapid-proton capture (rp) process. The rp process transforms CNO nuclei to heavier nuclei (up to iron and nickel) by a chain of successive proton captures and beta decays. Hydrogen and helium-burning reactions, including the 15O( alpha,gamma)19Ne breakout reaction and the subsequent rp process, are thought to be the energy source for novae on the surface of accreting neutron stars and are possibly responsible for the unusual concentrations of heavy elements recently observed in novae. At astrophysically important temperatures, the 15O(alpha,gamma) 19Ne reaction rate is determined by the properties of several resonances just above the alpha-particle threshold in 19 Ne (Ecm<1.2 MeV). This thesis involves a series of experiments which determine the reaction rate for the 15O(alpha,gamma)^ {19}Ne reaction by measuring the properties of these resonances. The ^{15

  17. Theoretical simulation of carrier capture and relaxation rates in quantum-dot semiconductor optical amplifiers

    SciTech Connect

    Wu, Yunhu; Zhang, Guoping; Guo, Ling; Qi, Guoqun; Li, Xiaoming

    2014-06-14

    Based on Auger scattering mechanism, carrier-carrier scattering dynamics between the two-dimensional carrier reservoir (also called wetting layer, i.e., WL) and the confined quantum dot ground and first excited state in quantum-dot semiconductor optical amplifiers (QD-SOAs) are investigated theoretically in this paper. The scattering rates for independent electron and hole densities are calculated. The results show an ultra-fast carrier capture (relaxation) rate up to 1 ps{sup −1}, and there is a complex dependence of the Coulomb scattering rates on the WL electron and hole densities. In addition, due to the different effective mass and the level distribution, the scattering rates for electron and hole are very different. Finally, in order to provide a direction to control (increase or decrease) the input current in realistic QD-SOA systems, a simple method is proposed to determine the trends of the carrier recovery rates with the WL carrier densities in the vicinity of the steady-state.

  18. Nuclear mass inventory, photon dose rate and thermal decay heat of spent research reactor fuel assemblies

    SciTech Connect

    Pond, R.B.; Matos, J.E.

    1996-12-31

    This document has been prepared to assist research reactor operators possessing spent fuel containing enriched uranium of United States origin to prepare part of the documentation necessary to ship this fuel to the United States. Data are included on the nuclear mass inventory, photon dose rate, and thermal decay heat of spent research reactor fuel assemblies. Isotopic masses of U, Np, Pu and Am that are present in spent research reactor fuel are estimated for MTR, TRIGA and DIDO-type fuel assembly types. The isotopic masses of each fuel assembly type are given as functions of U-235 burnup in the spent fuel, and of initial U-235 enrichment and U-235 mass in the fuel assembly. Photon dose rates of spent MTR, TRIGA and DIDO-type fuel assemblies are estimated for fuel assemblies with up to 80% U-235 burnup and specific power densities between 0.089 and 2.857 MW/kg[sup 235]U, and for fission product decay times of up to 20 years. Thermal decay heat loads are estimated for spent fuel based upon the fuel assembly irradiation history (average assembly power vs. elapsed time) and the spent fuel cooling time.

  19. Radionuclide mass inventory, activity, decay heat, and dose rate parametric data for TRIGA spent nuclear fuels

    SciTech Connect

    Sterbentz, J.W.

    1997-03-01

    Parametric burnup calculations are performed to estimate radionuclide isotopic mass and activity concentrations for four different Training, Research, and Isotope General Atomics (TRIGA) nuclear reactor fuel element types: (1) Aluminum-clad standard, (2) Stainless Steel-clad standard, (3) High-enrichment Fuel Life Improvement Program (FLIP), and (4) Low-enrichment Fuel Life Improvement Program (FLIP-LEU-1). Parametric activity data are tabulated for 145 important radionuclides that can be used to generate gamma-ray emission source terms or provide mass quantity estimates as a function of decay time. Fuel element decay heats and dose rates are also presented parametrically as a function of burnup and decay time. Dose rates are given at the fuel element midplane for contact, 3.0-feet, and 3.0-meter detector locations in air. The data herein are estimates based on specially derived Beginning-of-Life (BOL) neutron cross sections using geometrically-explicit TRIGA reactor core models. The calculated parametric data should represent good estimates relative to actual values, although no experimental data were available for direct comparison and validation. However, because the cross sections were not updated as a function of burnup, the actinide concentrations may deviate from the actual values at the higher burnups.

  20. Instrument for precision long-term β-decay rate measurements.

    PubMed

    Ware, M J; Bergeson, S D; Ellsworth, J E; Groesbeck, M; Hansen, J E; Pace, D; Peatross, J

    2015-07-01

    We describe an experimental setup for making precision measurements of relative β-decay rates of (22)Na, (36)Cl, (54)Mn, (60)Co, (90)Sr, (133)Ba, (137)Cs, (152)Eu, and (154)Eu. The radioactive samples are mounted in two automated sample changers that sequentially position the samples with high spatial precision in front of sets of detectors. The set of detectors for one sample changer consists of four Geiger-Müller (GM) tubes and the other set of detectors consists of two NaI scintillators. The statistical uncertainty in the count rate is few times 0.01% per day for the GM detectors and about 0.01% per hour on the NaI detectors. The sample changers, detectors, and associated electronics are housed in a sealed chamber held at constant absolute pressure, humidity, and temperature to isolate the experiment from environmental variations. The apparatus is designed to accumulate statistics over many years in a regulated environment to test recent claims of small annual variations in the decay rates. We demonstrate that absent this environmental regulation, uncontrolled natural atmospheric pressure variations at our location would imprint an annual signal of 0.1% on the Geiger-Müller count rate. However, neither natural pressure variations nor plausible indoor room temperature variations cause a discernible influence on our NaI scintillator detector count rate. PMID:26233381

  1. Instrument for precision long-term β-decay rate measurements

    SciTech Connect

    Ware, M. J. Bergeson, S. D.; Ellsworth, J. E.; Groesbeck, M.; Hansen, J. E.; Pace, D.; Peatross, J.

    2015-07-15

    We describe an experimental setup for making precision measurements of relative β-decay rates of {sup 22}Na, {sup 36}Cl, {sup 54}Mn, {sup 60}Co, {sup 90}Sr, {sup 133}Ba, {sup 137}Cs, {sup 152}Eu, and {sup 154}Eu. The radioactive samples are mounted in two automated sample changers that sequentially position the samples with high spatial precision in front of sets of detectors. The set of detectors for one sample changer consists of four Geiger-Müller (GM) tubes and the other set of detectors consists of two NaI scintillators. The statistical uncertainty in the count rate is few times 0.01% per day for the GM detectors and about 0.01% per hour on the NaI detectors. The sample changers, detectors, and associated electronics are housed in a sealed chamber held at constant absolute pressure, humidity, and temperature to isolate the experiment from environmental variations. The apparatus is designed to accumulate statistics over many years in a regulated environment to test recent claims of small annual variations in the decay rates. We demonstrate that absent this environmental regulation, uncontrolled natural atmospheric pressure variations at our location would imprint an annual signal of 0.1% on the Geiger-Müller count rate. However, neither natural pressure variations nor plausible indoor room temperature variations cause a discernible influence on our NaI scintillator detector count rate.

  2. Instrument for precision long-term β-decay rate measurements

    NASA Astrophysics Data System (ADS)

    Ware, M. J.; Bergeson, S. D.; Ellsworth, J. E.; Groesbeck, M.; Hansen, J. E.; Pace, D.; Peatross, J.

    2015-07-01

    We describe an experimental setup for making precision measurements of relative β-decay rates of 22Na, 36Cl, 54Mn, 60Co, 90Sr, 133Ba, 137Cs, 152Eu, and 154Eu. The radioactive samples are mounted in two automated sample changers that sequentially position the samples with high spatial precision in front of sets of detectors. The set of detectors for one sample changer consists of four Geiger-Müller (GM) tubes and the other set of detectors consists of two NaI scintillators. The statistical uncertainty in the count rate is few times 0.01% per day for the GM detectors and about 0.01% per hour on the NaI detectors. The sample changers, detectors, and associated electronics are housed in a sealed chamber held at constant absolute pressure, humidity, and temperature to isolate the experiment from environmental variations. The apparatus is designed to accumulate statistics over many years in a regulated environment to test recent claims of small annual variations in the decay rates. We demonstrate that absent this environmental regulation, uncontrolled natural atmospheric pressure variations at our location would imprint an annual signal of 0.1% on the Geiger-Müller count rate. However, neither natural pressure variations nor plausible indoor room temperature variations cause a discernible influence on our NaI scintillator detector count rate.

  3. Analysis of Growth and Decay Rates of the Axial Dipole in Geodynamo Models

    NASA Astrophysics Data System (ADS)

    Avery, M. S.; Constable, C.; Davies, C.; Gubbins, D.

    2013-12-01

    Observations of the Earth's magnetic field made at the surface reveal temporal variations in the field originating in the outer core. PADM2M is a reconstruction of the 0 to 2 Ma paleomagnetic axial dipole moment. Ziegler & Constable, 2011 showed that for periods longer than 25 kyr the rate of growth of the geomagnetic dipole is greater than its decay rate. This asymmetry is not limited to times when the field is reversing; this may be indicative of a key physical process of secular variation. To investigate the possible core processes underlying this observation we have analyzed a suite of numerical dynamo simulations, specifically the temporal variation of their axial dipole moments. We use the magnetic diffusion time to scale the simulations' nondimensional time, as this is more appropriate for the periods of interest here. An advantage to analyzing simulations is that they do not suffer from the same limitations in spatial and temporal resolution as the data; however, simulations cannot yet run with Earth-like rotational rates or diffusivities. All of our simulations span multiple diffusion times. We have chosen a broad range of simulations with different reversal regimes (dipole-dominated, non-reversing; dipole-dominated, reversing; multipolar, reversing) and with different heating modes (bottom, internal, or a combination of the two). For each simulation we conduct the same analysis that was applied to PADM2M. Families of smoothed axial dipole models are constructed using penalized smoothing splines as an effective low-pass filter to see at what timescales any asymmetry exist. The first derivatives of each axial dipole record are calculated in order to examine the rates of growth and decay. The results vary with the nature of the simulations. Further analysis is needed to determine what dynamo parameters, and related physical properties, determine the relative rates of growth and decay.

  4. Measurement of the production rates of η and η‧ in hadronic Z decays

    NASA Astrophysics Data System (ADS)

    Buskulic, D.; Decamp, D.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Mours, B.; Alemany, R.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Gaitan, V.; Garrido, Ll.; Pacheco, A.; Pascual, A.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Maggi, M.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Gao, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Lou, J.; Qiao, C.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhao, W.; Atwood, W. B.; Bauerdick, L. A. T.; Blucher, E.; Bonvicini, G.; Bossi, F.; Boudreau, J.; Burnett, T. H.; Drevermann, H.; Forty, R. W.; Hagelberg, R.; Harvey, J.; Haywood, S.; Hilgart, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lançon, E.; Lehraus, I.; Lohse, T.; Lusiani, A.; Martinez, M.; Mato, P.; Mattison, T.; Meinhard, H.; Menary, S.; Meyer, T.; Minten, A.; Miguel, R.; Moser, H.-G.; Nash, J.; Palazzi, P.; Perlas, J. A.; Ranjard, F.; Redlinger, G.; Rolandi, L.; Roth, A.; Rothberg, J.; Ruan, T.; Saich, M.; Schlatter, D.; Schmelling, M.; Sefkow, F.; Tejessy, W.; Wachsmuth, H.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Badaud, F.; Bardadin-Otwinowska, M.; Bencheikh, A. M.; El Fellous, R.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Pietrzyk, B.; Proriol, J.; Prulhière, F.; Stimpfl, G.; Fearnley, T.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nilsson, B. S.; Efthymiopoulos, I.; Kyriakis, A.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Badier, J.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Fouque, G.; Gamess, A.; Orteu, S.; Rosowsky, A.; Rougé, A.; Rumpf, M.; Tanaka, R.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Moneta, L.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Lannutti, J.; Levinthal, D.; Mermikides, M.; Sawyer, L.; Wasserbaech, S.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Picchi, P.; Altoon, B.; Boyle, O.; Colrain, P.; Ten Have, I.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Scarr, J. M.; Smith, K.; Thompson, A. S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geiges, R.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Belk, A. T.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Dugeay, S.; Greene, A. M.; Hassard, J. F.; Lieske, N. M.; Patton, S. J.; Payne, D. G.; Phillips, M. J.; Sedgbeer, J. K.; Tomalin, I. R.; Wright, A. G.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Patel, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Barczewski, T.; Kleinknecht, K.; Raab, J.; Renk, B.; Roehn, S.; Sander, H.-G.; Schmidt, H.; Steeg, F.; Walther, S. M.; Wolf, B.; Aubert, J.-J.; Benchouk, C.; Bernard, V.; Bonissent, A.; Carr, J.; Coyle, P.; Drinkard, J.; Etienne, F.; Papalexiou, S.; Payre, P.; Qian, Z.; Rousseau, D.; Schwemling, P.; Talby, M.; Adlung, S.; Bauer, C.; Blum, W.; Brown, D.; Cowan, G.; Dehning, B.; Dietl, H.; Dydak, F.; Fernandez-Bosman, M.; Frank, M.; Halley, A. W.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stierlin, U.; Stiegler, U.; St. Denis, R.; Takashima, M.; Thomas, J.; Wolf, G.; Bertin, V.; Boucrot, J.; Callot, O.; Chen, X.; Cordier, A.; Davier, M.; Grivaz, J.-F.; Heusse, Ph.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Veillet, J.-J.; Videau, I.; Zhang, Z.; Zomer, F.; Abbaneo, D.; Amendolia, S. R.; Bagliesi, G.; Batignani, G.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Carpinelli, M.; Ciocci, M. A.; Dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Focardi, E.; Forti, F.; Giassi, A.; Giorgi, M. A.; Ligabue, F.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Carter, J. M.; Green, M. G.; March, P. V.; Mir, Ll. M.; Medcalf, T.; Quazi, I. S.; Strong, J. A.; West, L. R.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Edwards, M.; Fisher, S. M.; Jones, T. J.; Norton, P. R.; Salmon, D. P.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Kozanecki, W.; Lemaire, M. C.; Locci, E.; Loucatos, S.; Monnier, E.; Perez, P.; Perrier, F.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Ashman, J. G.; Babbage, W.; Booth, C. N.; Buttar, C.; Carney, R. E.; Cartwright, S.; Combley, F.; Hatfield, F.; Reeves, P.; Thompson, L. F.; Barberio, E.; Brandt, S.; Grupen, C.; Mirabito, L.; Schäfer, U.; Ganis, G.; Giannini, G.; Gobbo, B.; Ragusa, F.; Bellantoni, L.; Cinabro, D.; Conway, J. S.; Cowen, D. F.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Jared, R. C.; Leclaire, B. W.; Lishka, C.; Pan, Y. B.; Pater, J. R.; Pusztaszeri, J.-F.; Saadi, Y.; Sharma, V.; Schmitt, M.; Shi, Z. H.; Walsh, A. M.; Weber, F. V.; Whitney, M. H.; Wu, Sau Lan; Wu, X.; Zobernig, G.; Aleph Collaboration

    1992-10-01

    The decays η → γγ and η‧ → ηπ+π- have been observed in hadronic decays of the Z produced at LEP. The fragmentation functions of both the η and η‧ have been measured. The measured multiplicities for x > 0.1 are 0.298±0.023±0.021 and 0.068±0.016 for η and η‧ respectively. While the fragmentation function for the η is fairly well described by the JETSET Monte Carlo, it is found that the production rate of the η‧ is a factor of four less than the corresponding prediction.

  5. Variation in radical decay rates in epoxy as a function of crosslink density

    NASA Technical Reports Server (NTRS)

    Kent, G. M.; Memory, J. M.; Gilbert, R. D.; Fornes, R. E.

    1983-01-01

    A study was made of the behavior of radicals generated by Co-60 gamma radiation in the epoxy system tetraglycidyl-4,4'-diaminodiphenyl methane (TGDDM) cured with 4,4'-diaminodiphenyl sulfone (DDS). The molar ratio of TGDDM to DDS was varied in the epoxy samples, and they were prepared under the same curing conditions to obtain various extents of crosslinking. ESR spectrometry data suggest that the rate of decay of radicals is related to inhomogeneities in the resin, with radicals in the highly crosslinked regions having long decay times. The inhomogeneities are thought to be due to statistical variation associated with the complex crosslinking reactions or to difficulties in mixing the reactants.

  6. Combined Results on b-Hadron Production Rates and Decay Properties

    SciTech Connect

    Su, Dong

    2002-09-11

    Combined results on b-hadron lifetimes, b-hadron production rates, B{sub d}{sup 0}-{bar B}{sub d}{sup 0} and B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations, the decay width difference between the mass eigenstates of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system, the average number of c and {bar c} quarks in b-hadron decays, and searches for CP violation in the B{sub d}{sup 0}-{bar B}{sub d}{sup 0} system are presented. They have been obtained from published and preliminary measurements available in Summer 2000 from the ALEPH, CDF, DELPHI, L3, OPAL and SLD Collaborations. These results have been used to determine the parameters of the CKM unitarity triangle.

  7. Role of the bound-state wave function in capture-loss rates: Slow proton in an electron gas

    SciTech Connect

    Alducin, M.; Nagy, I.

    2003-07-01

    Capture and loss rates for protons moving in an electron gas are calculated using many-body perturbation theory. The role of the form of the bound-state wave function for weakly bound states around the proton is analyzed. We find significant differences (up to a factor of 2 higher) in the values of Auger capture and loss rates when using Hulthen-type instead of hydrogenic wave functions. Its relevance in stopping power is briefly discussed.

  8. Optimal Decay Rate of the Compressible Navier-Stokes-Poisson System in {mathbb {R}^3}

    NASA Astrophysics Data System (ADS)

    Li, Hai-Liang; Matsumura, Akitaka; Zhang, Guojing

    2010-05-01

    The compressible Navier-Stokes-Poisson (NSP) system is considered in {mathbb {R}^3} in the present paper, and the influences of the electric field of the internal electrostatic potential force governed by the self-consistent Poisson equation on the qualitative behaviors of solutions is analyzed. It is observed that the rotating effect of electric field affects the dispersion of fluids and reduces the time decay rate of solutions. Indeed, we show that the density of the NSP system converges to its equilibrium state at the same L 2-rate {(1+t)^{-frac {3}{4}}} or L ∞-rate (1 + t)-3/2 respectively as the compressible Navier-Stokes system, but the momentum of the NSP system decays at the L 2-rate {(1+t)^{-frac {1}{4}}} or L ∞-rate (1 + t)-1 respectively, which is slower than the L 2-rate {(1+t)^{-frac {3}{4}}} or L ∞-rate (1 + t)-3/2 for compressible Navier-Stokes system [Duan et al., in Math Models Methods Appl Sci 17:737-758, 2007; Liu and Wang, in Comm Math Phys 196:145-173, 1998; Matsumura and Nishida, in J Math Kyoto Univ 20:67-104, 1980] and the L ∞-rate (1 + t)- p with {p in (1, 3/2)} for irrotational Euler-Poisson system [Guo, in Comm Math Phys 195:249-265, 1998]. These convergence rates are shown to be optimal for the compressible NSP system.

  9. Initial colonization, community assembly and ecosystem function: fungal colonist traits and litter biochemistry mediate decay rate.

    PubMed

    Cline, Lauren C; Zak, Donald R

    2015-10-01

    Priority effects are an important ecological force shaping biotic communities and ecosystem processes, in which the establishment of early colonists alters the colonization success of later-arriving organisms via competitive exclusion and habitat modification. However, we do not understand which biotic and abiotic conditions lead to strong priority effects and lasting historical contingencies. Using saprotrophic fungi in a model leaf decomposition system, we investigated whether compositional and functional consequences of initial colonization were dependent on initial colonizer traits, resource availability or a combination thereof. To test these ideas, we factorially manipulated leaf litter biochemistry and initial fungal colonist identity, quantifying subsequent community composition, using neutral genetic markers, and community functional characteristics, including enzyme potential and leaf decay rates. During the first 3 months, initial colonist respiration rate and physiological capacity to degrade plant detritus were significant determinants of fungal community composition and leaf decay, indicating that rapid growth and lignolytic potential of early colonists contributed to altered trajectories of community assembly. Further, initial colonization on oak leaves generated increasingly divergent trajectories of fungal community composition and enzyme potential, indicating stronger initial colonizer effects on energy-poor substrates. Together, these observations provide evidence that initial colonization effects, and subsequent consequences on litter decay, are dependent upon substrate biochemistry and physiological traits within a regional species pool. Because microbial decay of plant detritus is important to global C storage, our results demonstrate that understanding the mechanisms by which initial conditions alter priority effects during community assembly may be key to understanding the drivers of ecosystem-level processes. PMID:26331892

  10. Optimal decay rate of the non-isentropic compressible Navier-Stokes-Poisson system in R

    NASA Astrophysics Data System (ADS)

    Zhang, Guojing; Li, Hai-Liang; Zhu, Changjiang

    In this paper, the compressible non-isentropic Navier-Stokes-Poisson (NSP) system is considered in R and the influences of internal electric field on the qualitative behaviors of solutions are analyzed. We observe that the electric field leads to the rotating phenomena in charge transport and reduces the speed of fluid motion, but it does not influence the transport of charge density and the heat diffusion. Indeed, we show that both density and temperature of the NSP system converge to their equilibrium state at the same rate (1 as the non-isentropic compressible Navier-Stokes system, but the momentum decays at the rate (1, which is slower than the rate (1 for the pure compressible Navier-Stokes system. These convergence rates are also shown to be optimal for the non-isentropic compressible NSP system.

  11. Neutron capture production rates of cosmogenic 60Co, 59Ni and 36Cl in stony meteorites

    NASA Technical Reports Server (NTRS)

    Spergel, M. S.; Reedy, R. C.; Lazareth, O. W.; Levy, P. W.

    1986-01-01

    Results for neutron flux calculations in stony meteoroids (of various radii and compositions) and production rates for Cl-36, Ni-59, and Co-60 are reported. The Ni-59/Co-60 ratio is nearly constant with depth in most meteorites: this effect is consistent with the neutron flux and capture cross section properties. The shape of the neutron flux energy spectrum, varies little with depth in a meteorite. The size of the parent meteorite can be determined from one of its fragments, using the Ni-59/Co-60 ratios, if the parent meteorite was less than 75 g/cm(2) in radius. If the parent meteorite was larger, a lower limit on the size of the parent meteorite can be determined from a fragment. In C3 chondrites this is not possible. In stony meteorites with R less than 50 g/cm(2) the calculated Co-60 production rates (mass less than 4 kg), are below 1 atom/min g-Co. The highest Co-60 production rates occur in stony meteorites with radius about 250 g/cm(2) (1.4 m across). In meteorites with radii greater than 400 g/cm(2), the maximum Co-60 production rate occurs at a depth of about 175 g/cm(2) in L-chondrite, 125 g/cm(2) in C3 chrondrite, and 190 g/cm(2) in aubrites.

  12. Toward Capturing Momentary Changes of Heart Rate Variability by a Dynamic Analysis Method

    PubMed Central

    Zhang, Haoshi; Zhu, Mingxing; Zheng, Yue; Li, Guanglin

    2015-01-01

    The analysis of heart rate variability (HRV) has been performed on long-term electrocardiography (ECG) recordings (12~24 hours) and short-term recordings (2~5 minutes), which may not capture momentary change of HRV. In this study, we present a new method to analyze the momentary HRV (mHRV). The ECG recordings were segmented into a series of overlapped HRV analysis windows with a window length of 5 minutes and different time increments. The performance of the proposed method in delineating the dynamics of momentary HRV measurement was evaluated with four commonly used time courses of HRV measures on both synthetic time series and real ECG recordings from human subjects and dogs. Our results showed that a smaller time increment could capture more dynamical information on transient changes. Considering a too short increment such as 10 s would cause the indented time courses of the four measures, a 1-min time increment (4-min overlapping) was suggested in the analysis of mHRV in the study. ECG recordings from human subjects and dogs were used to further assess the effectiveness of the proposed method. The pilot study demonstrated that the proposed analysis of mHRV could provide more accurate assessment of the dynamical changes in cardiac activity than the conventional measures of HRV (without time overlapping). The proposed method may provide an efficient means in delineating the dynamics of momentary HRV and it would be worthy performing more investigations. PMID:26172953

  13. Application of the renormalization group to the calculation of the vacuum decay rate in flat and curved space-time

    NASA Astrophysics Data System (ADS)

    Metaxas, Dimitrios

    2007-02-01

    I show that an application of renormalization group arguments may lead to significant corrections to the vacuum decay rate for phase transitions in flat and curved space-time. It can also give some information regarding its dependence on the parameters of the theory, including the cosmological constant in the case of decay in curved space-time.

  14. Determination of HF artificial ionospheric turbulence characteristics using comparison of calculated plasma wave decay rates with the measured see decay rates

    NASA Astrophysics Data System (ADS)

    Grach, Savely; Bareev, Denis; Gavrilenko, Vladimir; Sergeev, Evgeny

    Damping rates of plasma waves with ω ˜ ωuh (ω is the plasma wave frequency, ωuh is the upper hybrid frequency) were calculated for frequencies close to and distant from the double resonance where ωuh ˜ nωce (ωce is the electron cyclotron frequency, n=4,5 are the gyroharmonic num-bers). The calculations were performed numerically on the base of full plasma wave dispersion relation not restricted by both the 'long wave limit' and 'short wave limit', i.e. a fulfillment of the inequalities |∆| |k |vTe and |∆| |k |vTe was not required. Here ∆ = ω - nωce , vTe = (Te /me )1/2 is the electron thermal velocity and k is the projection of the wave vector onto the magnetic field direction. It is shown that the plasma wave damping rates do not differ noticeably from ones calculated under the long wave and short wave limits. The results obtained are compared with the data of the relaxation of the stimulated electromagnetic emission (SEE) after the pump wave turn off, which demonstrate an essential decrease of the relaxation time near 4th electron gyroharmonic, so far as the SEE relaxation is attributed to the damping of plasma waves responsible for the SEE generation. The comparison allows to determine characteristics of plasma waves mostly contributing to the SEE generation, such as wave numbers and the angles between the wave vectors and geomagnetic field, and the altitude region of the SEE source. The dependence of the decay rate on ∆ can be applied also to interpretation of the SEE spectral shape at different pump frequencies near gyroharmonics. The work is supported by RFBR grants 10-02-00642, 09-02-01150 and Federal Special-purpose Program "Scientific and pedagogical personnel of innovative Russia".

  15. Simultaneous use of mark-recapture and radiotelemetry to estimate survival, movement, and capture rates

    USGS Publications Warehouse

    Powell, L.A.; Conroy, M.J.; Hines, J.E.; Nichols, J.D.; Krementz, D.G.

    2000-01-01

    Biologists often estimate separate survival and movement rates from radio-telemetry and mark-recapture data from the same study population. We describe a method for combining these data types in a single model to obtain joint, potentially less biased estimates of survival and movement that use all available data. We furnish an example using wood thrushes (Hylocichla mustelina) captured at the Piedmont National Wildlife Refuge in central Georgia in 1996. The model structure allows estimation of survival and capture probabilities, as well as estimation of movements away from and into the study area. In addition, the model structure provides many possibilities for hypothesis testing. Using the combined model structure, we estimated that wood thrush weekly survival was 0.989 ? 0.007 ( ?SE). Survival rates of banded and radio-marked individuals were not different (alpha hat [S_radioed, ~ S_banded]=log [S hat _radioed/ S hat _banded]=0.0239 ? 0.0435). Fidelity rates (weekly probability of remaining in a stratum) did not differ between geographic strata (psi hat=0.911 ? 0.020; alpha hat [psi11, psi22]=0.0161 ? 0.047), and recapture rates ( = 0.097 ? 0.016) banded and radio-marked individuals were not different (alpha hat [p_radioed, p_banded]=0.145 ? 0.655). Combining these data types in a common model resulted in more precise estimates of movement and recapture rates than separate estimation, but ability to detect stratum or mark-specific differences in parameters was week. We conducted simulation trials to investigate the effects of varying study designs on parameter accuracy and statistical power to detect important differences. Parameter accuracy was high (relative bias [RBIAS] <2 %) and confidence interval coverage close to nominal, except for survival estimates of banded birds for the 'off study area' stratum, which were negatively biased (RBIAS -7 to -15%) when sample sizes were small (5-10 banded or radioed animals 'released' per time interval). To provide

  16. Desorption due to Recoil Induced by Neutrino Emission and Auger Relaxation of CHLORINE-37 Following the Electron Capture Decay of ARGON-37.

    NASA Astrophysics Data System (ADS)

    Zhu, Lin

    1995-01-01

    A novel experiment was developed in this work to study the desorption and the Auger relaxation processes of ^{37}Cl following the ^{37}Ar electron capture decay. For the first time, the desorption of ^{37}Cl ions due to recoil induced by neutrino emission in this decay process was observed. The kinetic energy distribution of the desorbing ^{37}Cl ions was accurately measured by using coincidence techniques. The resulting ^{37}Cl ion energy ranges from 5 eV to 13 eV with a maximum at around 9 eV and an FWHM about 3 eV. The charge state distribution of the desorbing ^{37}Cl ions was also measured. The resulting charge state distribution is: 53% of the total ions have charge +e, 21% have charge +2e and 26% have charge +ne, where n >= 3. The desorbing probability of ^ {37}Cl ions was measured by two independent experiments which gave the result of 9.4+/-1.2 %. The energy distribution, the charge state distribution and the desorbing probability of ^{37}Cl ions are all quite different as compared with the expected values for an isolated Cl atom. These differences are explained in the desorption model involving charge exchange and Coulomb repulsion between ^{37}Cl ions and their surrounding atoms. The electron capture decay also creates a highly unusual initial state in the ^{37 }Cl atom which allows direct observation of some novel relaxation processes which are amenable to many body theory, but essentially impossible to probe experimentally with conventional techniques. For the first time, direct evidence of the double Auger decay of a K-hole and the large shift in energy (22 eV) of an LMM Auger line was reported. The double Auger decay probability and energy distribution of the two double Auger electrons were measured by using coincidence techniques. The resulting double Auger decay probability ranges from 12+/-0.3 % to 15+/-0.4% of the total Auger decay. The preferred energy distribution of the double Auger emission is for one of the electrons to take most of the

  17. The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes

    USGS Publications Warehouse

    Kirwanm, M.L.; Langley, J.A.; Guntenspergen, Gleen R.; Megonigal, J.P.

    2013-01-01

    The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-level rise, relatively little is known about how decomposition rates will respond to sea-level rise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-level rise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive accelerating sea-level rise.

  18. The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes

    NASA Astrophysics Data System (ADS)

    Kirwan, M. L.; Langley, J. A.; Guntenspergen, G. R.; Megonigal, J. P.

    2013-03-01

    The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-level rise, relatively little is known about how decomposition rates will respond to sea-level rise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-level rise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive accelerating sea-level rise.

  19. Mixture models for estimating the size of a closed population when capture rates vary among individuals

    USGS Publications Warehouse

    Dorazio, R.M.; Royle, J. Andrew

    2003-01-01

    We develop a parameterization of the beta-binomial mixture that provides sensible inferences about the size of a closed population when probabilities of capture or detection vary among individuals. Three classes of mixture models (beta-binomial, logistic-normal, and latent-class) are fitted to recaptures of snowshoe hares for estimating abundance and to counts of bird species for estimating species richness. In both sets of data, rates of detection appear to vary more among individuals (animals or species) than among sampling occasions or locations. The estimates of population size and species richness are sensitive to model-specific assumptions about the latent distribution of individual rates of detection. We demonstrate using simulation experiments that conventional diagnostics for assessing model adequacy, such as deviance, cannot be relied on for selecting classes of mixture models that produce valid inferences about population size. Prior knowledge about sources of individual heterogeneity in detection rates, if available, should be used to help select among classes of mixture models that are to be used for inference.

  20. Solving the Neutrino Mass Mystery using Double Beta Decay. An Examination of the Feasibility of Xennoon Purification and Ion Capture and Release using an Electrostatic Probe

    SciTech Connect

    Outschoorn, Verena M

    2003-09-05

    Double beta decay has long been recognized as a useful avenue for the study of electron neutrinos, especially the neutrino mass and its fundamental nature (Majorana or Dirac). Recent neutrino oscillation experiments have provided compelling evidence that the neutrino has mass. The detection of the neutrinoless mode of double beta decay would finally set a lower limit on the mass of the electron neutrino, as well as prove that the neutrino is a Majorana particle (with opposite spin, it is its own anti-particle). The Enriched Xenon Observatory (EXO) project attempts to detect neutrinoless double beta decay using {sup 136}Xe that decays by this process to {sup 136}Ba{sup 2} + e{sup -} + e{sup -}. Perhaps one of the most significant characteristics of this project is the reduction of the background through the identification of the Barium ions for each individual event using laser fluorescence techniques. This project also proposes to collect scintillation light in addition to the ionization electrons in order to further improve energy resolution. Current work at SLAC includes the development of a purification system for xenon, as well as tests for the capture and release of single ions using an electrostatic probe.

  1. Electron capture and positron decay of /sup 206/Fr and /sup 208/Fr and the energy levels of /sup 206/Rn and /sup 208/Rn

    SciTech Connect

    Ritchie, B.G.; Avignone, F.T. III; Carter, H.K.; Mlekodaj, R.L.; Spejewski, E.H.

    1981-04-01

    The isotopes /sup 206/Fr and /sup 208/Fr were produced by the reactions Ir(/sup 20/Ne,xn)/sup 206,208/Fr and mass separated on-line. The electron-capture and positron decays to /sup 206/Rn and /sup 208/Rn were studied by collecting ..gamma.. ray and internal conversion electron singles spectra as a function of decay time as well as ..gamma..-..gamma.., ..gamma..-e/sup -/, and ..gamma..-x ray coincidence spectra. The energies and many of the spins were determined for 18 excited, even parity states in /sup 208/Rn and for 10 excited, even parity states in /sup 206/Rn. These nuclei appear to be excellent candidates for interpretation in terms of a weak coupling shell model. The energy levels were also compared to the predictions of the interacting boson approximation model.

  2. Comparison of the perfluorocarbon and tracer gas decay methods for assessing infiltration rates in residents

    SciTech Connect

    Schaap, L.; Leaderer, B.P.; Renes, S.; Verstraelen, H.; Tosun, T.; Dietz, R.N.

    1985-01-01

    The passive perfluorocarbon tracer (PFT) technique for determining air infiltration rates into homes and buildings was evaluated in an environmental chamber. The impact of sampler orientation at a constant ventilation rate and a constant temperature, of variable ventilation rate at a constant temperature, and of variable temperature at a constant ventilation rate were evaluated. The average relative standard deviation of 16 paired samplers deployed in experiment 1 was +- 1.9% +- 1.0% indicating good reproducibility of the passive sampling rate and sample analysis. No impact of sampler orientation with respect to low air velocities (<0.2 m/s) present in houses is expected. The passive samplers accurately measured the average tracer concentration as compared with calculations based on the known source strength (CO/sub 2/ decays) and the measured ventilation rate under conditions of a 3-fold variation in ventilation rates (experiment 2). Temperature cycling differences of 8/sup 0/C (experiment 3) did not produce a bias in the PFT determined ventilation rate. The PFT technique is applicable to the expected range of condition in homes and buildings. 3 refs., 1 fig., 1 tab.

  3. Analysis of flow decay potential on Galileo. [oxidizer flow rate reduction by iron nitrate precipitates

    NASA Technical Reports Server (NTRS)

    Cole, T. W.; Frisbee, R. H.; Yavrouian, A. H.

    1987-01-01

    The risks posed to the NASA's Galileo spacecraft by the oxidizer flow decay during its extended mission to Jupiter is discussed. The Galileo spacecraft will use nitrogen tetroxide (NTO)/monomethyl hydrazine bipropellant system with one large engine thrust-rated at a nominal 400 N, and 12 smaller engines each thrust-rated at a nominal 10 N. These smaller thrusters, because of their small valve inlet filters and small injector ports, are especially vulnerable to clogging by iron nitrate precipitates formed by NTO-wetted stainless steel components. To quantify the corrosion rates and solubility levels which will be seen during the Galileo mission, corrosion and solubility testing experiments were performed with simulated Galileo materials, propellants, and environments. The results show the potential benefits of propellant sieving in terms of iron and water impurity reduction.

  4. Derivative expansion and gauge independence of the false vacuum decay rate in various gauges

    NASA Astrophysics Data System (ADS)

    Metaxas, D.

    2001-04-01

    In theories with radiative symmetry breaking, the calculation of the false vacuum decay rate requires the inclusion of higher-order terms in the derivative expansion of the effective action. I show here that, in the case of covariant gauges, the presence of infrared singularities forbids the consistent calculation by keeping the lowest-order terms. The situation is remedied, however, in the case of Rξ gauges. Using the Nielsen identities I show that the final result is gauge independent for generic values of the gauge parameter v that are not anomalously small.

  5. An Examination of Sunspot Number Rates of Growth and Decay in Relation to the Sunspot Cycle

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2006-01-01

    On the basis of annual sunspot number averages, sunspot number rates of growth and decay are examined relative to both minimum and maximum amplitudes and the time of their occurrences using cycles 12 through present, the most reliably determined sunspot cycles. Indeed, strong correlations are found for predicting the minimum and maximum amplitudes and the time of their occurrences years in advance. As applied to predicting sunspot minimum for cycle 24, the next cycle, its minimum appears likely to occur in 2006, especially if it is a robust cycle similar in nature to cycles 17-23.

  6. Comparison of nonmesonic hypernuclear decay rates computed in laboratory and center-of-mass coordinates

    SciTech Connect

    De Conti, C.; Barbero, C.; Galeão, A. P.; Krmpotić, F.

    2014-11-11

    In this work we compute the one-nucleon-induced nonmesonic hypernuclear decay rates of {sub Λ}{sup 5}He, {sub Λ}{sup 12}C and {sub Λ}{sup 13}C using a formalism based on the independent particle shell model in terms of laboratory coordinates. To ascertain the correctness and precision of the method, these results are compared with those obtained using a formalism in terms of center-of-mass coordinates, which has been previously reported in the literature. The formalism in terms of laboratory coordinates will be useful in the shell-model approach to two-nucleon-induced transitions.

  7. Analysis of decay dose rates and dose management in the National Ignition Facility.

    PubMed

    Khater, Hesham; Brereton, Sandra; Dauffy, Lucile; Hall, Jim; Hansen, Luisa; Kim, Soon; Kohut, Tom; Pohl, Bertram; Sitaraman, Shiva; Verbeke, Jerome; Young, Mitchell

    2013-06-01

    A detailed model of the Target Bay (TB) at the National Ignition Facility (NIF) has been developed to estimate the post-shot radiation environment inside the facility. The model includes the large number of structures and diagnostic instruments present inside the TB. These structures and instruments are activated by neutrons generated during a shot, and the resultant gamma dose rates are estimated at various decay times following the shot. A set of computational tools was developed to help in estimating potential radiation exposure to TB workers. The results presented in this paper describe the expected radiation environment inside the TB following a low-yield DT shot of 10(16) neutrons. General environment dose rates drop below 30 μSv h(-1) within 3 h following a shot, with higher dose rates observed in the vicinity (~30 cm) of few components. The dose rates drop by more than a factor of two at 1 d following the shot. Dose rate maps of the different TB levels were generated to aid in estimating worker stay-out times following a shot before entry is permitted into the TB. Primary components, including the Target Chamber and diagnostic and beam line components, are constructed of aluminum. Near-term TB accessibility is driven by the decay of the aluminum activation product, 24Na. Worker dose is managed using electronic dosimeters (EDs) self-issued at kiosks using commercial dose management software. The software programs the ED dose and dose rate alarms based on the Radiological Work Permit (RWP) and tracks dose by individual, task, and work group. PMID:23629063

  8. Relativistic two-photon decay rates with the Lagrange-mesh method

    NASA Astrophysics Data System (ADS)

    Filippin, Livio; Godefroid, Michel; Baye, Daniel

    2016-01-01

    Relativistic two-photon decay rates of the 2 s1 /2 and 2 p1 /2 states towards the 1 s1 /2 ground state of hydrogenic atoms are calculated by using numerically exact energies and wave functions obtained from the Dirac equation with the Lagrange-mesh method. This approach is an approximate variational method taking the form of equations on a grid because of the use of a Gauss quadrature approximation. Highly accurate values are obtained by a simple calculation involving different meshes for the initial, final, and intermediate wave functions and for the calculation of matrix elements. The accuracy of the results with a Coulomb potential is improved by several orders of magnitude in comparison with benchmark values from the literature. The general requirement of gauge invariance is also successfully tested, down to rounding errors. The method provides high accuracies for two-photon decay rates of a particle in other potentials and is applied to a hydrogen atom embedded in a Debye plasma simulated by a Yukawa potential.

  9. Sensitivity of β -decay rates to the radial dependence of the nucleon effective mass

    NASA Astrophysics Data System (ADS)

    Severyukhin, A. P.; Margueron, J.; Borzov, I. N.; Van Giai, N.

    2015-03-01

    We analyze the sensitivity of β -decay rates in 78Ni and Sn,132100 to a correction term in Skyrme energy-density functionals (EDFs) which modifies the radial shape of the nucleon effective mass. This correction is added on top of several Skyrme parametrizations which are selected from their effective mass properties and predictions about the stability properties of 132Sn . The impact of the correction on high-energy collective modes is shown to be moderate. From the comparison of the effects induced by the surface-peaked effective mass in the three doubly magic nuclei, it is found that 132Sn is largely impacted by the correction, while 78Ni and 100Sn are only moderately affected. We conclude that β -decay rates in these nuclei can be used as a test of different parts of the nuclear EDF: 78Ni and 100Sn are mostly sensitive to the particle-hole interaction through the B (GT) values, while 132Sn is sensitive to the radial shape of the effective mass. Possible improvements of these different parts could therefore be better constrained in the future.

  10. Initial measurements of O-ion and He-ion decay rates observed from the Van Allen probes RBSPICE instrument

    PubMed Central

    Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob; Keika, Kunihiro

    2014-01-01

    H-ion (∼45 keV to ∼600 keV), He-ion (∼65 keV to ∼520 keV), and O-ion (∼140 keV to ∼1130 keV) integral flux measurements, from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft B, are reported. These abundance data form a cohesive picture of ring current ions during the first 9 months of measurements. Furthermore, the data presented herein are used to show injection characteristics via the He-ion/H-ion abundance ratio and the O-ion/H-ion abundance ratio. Of unique interest to ring current dynamics are the spatial-temporal decay characteristics of the two injected populations. We observe that He-ions decay more quickly at lower L shells, on the order of ∼0.8 day at L shells of 3–4, and decay more slowly with higher L shell, on the order of ∼1.7 days at L shells of 5–6. Conversely, O-ions decay very rapidly (∼1.5 h) across all L shells. The He-ion decay time are consistent with previously measured and calculated lifetimes associated with charge exchange. The O-ion decay time is much faster than predicted and is attributed to the inclusion of higher-energy (> 500 keV) O-ions in our decay rate estimation. We note that these measurements demonstrate a compelling need for calculation of high-energy O-ion loss rates, which have not been adequately studied in the literature to date. Key Points We report initial observations of ring current ions We show that He-ion decay rates are consistent with theory We show that O-ions with energies greater than 500 keV decay very rapidly PMID:26167435

  11. Vacuum stability and Higgs diphoton decay rate in the Zee-Babu model

    NASA Astrophysics Data System (ADS)

    Chao, Wei; Zhang, Jian-Hui; Zhang, Yongchao

    2013-06-01

    Although recent Higgs data from ATLAS and CMS are compatible with a Standard Model (SM) signal at 2σ level, both experiments see indications for an excess in the diphoton decay channel, which points to new physics beyond the SM. Given such a low Higgs mass m H ~ 125 GeV, another sign indicating the existence of new physics beyond the SM is the vacuum stability problem, i.e., the SM Higgs quartic coupling may run to negative values at a scale below the Planck scale. In this paper, we study the vacuum stability and enhanced Higgs diphoton decay rate in the Zee-Babu model, which was used to generate tiny Majorana neutrino masses at two-loop level. We find that it is rather difficult to find overlapping regions allowed by the vacuum stability and diphoton enhancement constraints. As a consequence, it is almost inevitable to introduce new ingredients into the model, in order to resolve these two issues simultaneously.

  12. Tracing nitrogen accumulation in decaying wood and examining its impact on wood decomposition rate

    NASA Astrophysics Data System (ADS)

    Rinne, Katja T.; Rajala, Tiina; Peltoniemi, Krista; Chen, Janet; Smolander, Aino; Mäkipää, Raisa

    2016-04-01

    Decomposition of dead wood, which is controlled primarily by fungi is important for ecosystem carbon cycle and has potentially a significant role in nitrogen fixation via diazotrophs. Nitrogen content has been found to increase with advancing wood decay in several studies; however, the importance of this increase to decay rate and the sources of external nitrogen remain unclear. Improved knowledge of the temporal dynamics of wood decomposition rate and nitrogen accumulation in wood as well as the drivers of the two processes would be important for carbon and nitrogen models dealing with ecosystem responses to climate change. To tackle these questions we applied several analytical methods on Norway spruce logs from Lapinjärvi, Finland. We incubated wood samples (density classes from I to V, n=49) in different temperatures (from 8.5oC to 41oC, n=7). After a common seven day pre-incubation period at 14.5oC, the bottles were incubated six days in their designated temperature prior to CO2 flux measurements with GC to determine the decomposition rate. N2 fixation was measured with acetylene reduction assay after further 48 hour incubation. In addition, fungal DNA, (MiSeq Illumina) δ15N and N% composition of wood for samples incubated at 14.5oC were determined. Radiocarbon method was applied to obtain age distribution for the density classes. The asymbiotic N2 fixation rate was clearly dependent on the stage of wood decay and increased from stage I to stage IV but was substantially reduced in stage V. CO2 production was highest in the intermediate decay stage (classes II-IV). Both N2 fixation and CO2 production were highly temperature sensitive having optima in temperature 25oC and 31oC, respectively. We calculated the variation of annual levels of respiration and N2 fixation per hectare for the study site, and used the latter data together with the 14C results to determine the amount of N2 accumulated in wood in time. The proportion of total nitrogen in wood

  13. Indoor acrolein emission and decay rates resulting from domestic cooking events

    NASA Astrophysics Data System (ADS)

    Seaman, Vincent Y.; Bennett, Deborah H.; Cahill, Thomas M.

    2009-12-01

    Acrolein (2-propenal) is a common constituent of both indoor and outdoor air, can exacerbate asthma in children, and may contribute to other chronic lung diseases. Recent studies have found high indoor levels of acrolein and other carbonyls compared to outdoor ambient concentrations. Heated cooking oils produce considerable amounts of acrolein, thus cooking is likely an important source of indoor acrolein. A series of cooking experiments were conducted to determine the emission rates of acrolein and other volatile carbonyls for different types of cooking oils (canola, soybean, corn and olive oils) and deep-frying different food items. Similar concentrations and emission rates of carbonyls were found when different vegetable oils were used to deep-fry the same food product. The food item being deep-fried was generally not a significant source of carbonyls compared to the cooking oil. The oil cooking events resulted in high concentrations of acrolein that were in the range of 26.4-64.5 μg m -3. These concentrations exceed all the chronic regulatory exposure limits and many of the acute exposure limits. The air exchange rate and the decay rate of the carbonyls were monitored to estimate the half-life of the carbonyls. The half-life for acrolein was 14.4 ± 2.6 h, which indicates that indoor acrolein concentrations can persist for considerable time after cooking in poorly-ventilated homes.

  14. Cooperative Lamb shift and the cooperative decay rate for an initially detuned phased state

    SciTech Connect

    Friedberg, Richard; Manassah, Jamal T.

    2010-04-15

    The cooperative Lamb shift (CLS) is hard to measure because in samples much larger than a resonant wavelength it is much smaller, for an initially prepared resonantly phased state, than the cooperative decay rate (CDR). We show, however, that if the phasing of the initial state is detuned so that the spatial wave vector is k{sub 1} congruent with k{sub 0{+-}}O((1/R)) (where k{sub 0}={omega}{sub 0}/c is the resonant frequency), the CLS grows to 'giant' magnitudes making it comparable to the CDR. Moreover, for certain controlled values of detuning, the initial CDR becomes small so that the dynamical Lamb shift (DLS) can be measured over a considerable period of time.

  15. Spontaneous decay rate and Casimir-Polder potential of an atom near a lithographed surface

    NASA Astrophysics Data System (ADS)

    Bennett, Robert

    2015-08-01

    Radiative corrections to an atom are calculated near a half-space that has arbitrarily shaped small depositions upon its surface. The method is based on calculation of the classical Green's function of the macroscopic Maxwell equations near an arbitrarily perturbed half-space using a Born-series expansion about the bare half-space Green's function. The formalism of macroscopic quantum electrodynamics is used to carry this over into the quantum picture. The broad utility of the calculated Green's function is demonstrated by using it to calculate two quantities: the spontaneous decay rate of an atom near a sharp surface feature and the Casimir-Polder potential of a finite grating deposited on a substrate. Qualitatively different behavior is found for the latter case where it is observed that the periodicity of the Casimir-Polder potential persists even outside the immediate vicinity of the grating.

  16. Combined results on b-hadron production rates, lifetimes, oscillations and semileptonic decays

    SciTech Connect

    WIllocq, stephane

    2000-08-02

    Combined results on b-hadron lifetimes, b-hadron production rates B{sub d}{sup 0}--Anti-B{sub d}{sup 0} and B{sub s}{sup 0}--Anti-B{sub s}{sup 0} oscillations, the decay width difference between the mass eigenstates of the B{sub s}{sup 0}--Anti-B{sub s}{sup 0} system, and the values of the CKM matrix elements {vert_bar}V{sub cb}{vert_bar} and {vert_bar}V{sub ub}{vert_bar} are obtained from published and preliminary measurements available in Summer 99 from the ALEPH, CDF, DELPHI, L3, OPAL and SLD Collaborations.

  17. Design of cycler trajectories and analysis of solar influences on radioactive decay rates during space missions

    NASA Astrophysics Data System (ADS)

    Rogers, Blake A.

    This thesis investigates the design of interplanetary missions for the continual habitation of Mars via Earth-Mars cyclers and for the detection of variations in nuclear decay rates due to solar influences. Several cycler concepts have been proposed to provide safe and comfortable quarters for astronauts traveling between the Earth and Mars. However, no literature has appeared to show how these massive vehicles might be placed into their cycler trajectories. Trajectories are designed that use either Vinfinity leveraging or low thrust to establish cycler vehicles in their desired orbits. In the cycler trajectory cases considered, the use of Vinfinity leveraging or low thrust substantially reduces the total propellant needed to achieve the cycler orbit compared to direct orbit insertion. In the case of the classic Aldrin cycler, the propellant savings due to Vinfinity leveraging can be as large as a 24 metric ton reduction for a cycler vehicle with a dry mass of 75 metric tons, and an additional 111 metric ton reduction by instead using low thrust. The two-synodic period cyclers considered benefit less from Vinfinity leveraging, but have a smaller total propellant mass due to their lower approach velocities at Earth and Mars. It turns out that, for low-thrust establishment, the propellant required is approximately the same for each of the cycler trajectories. The Aldrin cycler has been proposed as a transportation system for human missions between Earth and Mars. However, the hyperbolic excess velocity values at the planetary encounters for these orbits are infeasibly large, especially at Mars. In a new version of the Aldrin cycler, low thrust is used in the interplanetary trajectories to reduce the encounter velocities. Reducing the encounter velocities at both planets reduces the propellant needed by the taxis (astronauts use these taxis to transfer between the planetary surfaces and the cycler vehicle) to perform hyperbolic rendezvous. While the propellant

  18. Rate of Temperature Decay in Human Muscle Following 3 MHz Ultrasound: The Stretching Window Revealed

    PubMed Central

    Draper, David O.; Ricard, Mark D.

    1995-01-01

    Researchers have determined that when therapeutic ultrasound vigorously heats connective tissue, it can be effective in increasing extensibility of collagen affected by scar tissue. These findings give credence to the use of continuous thermal ultrasound to heat tissue before stretching, exercise, or friction massage in an effort to decrease joint contractures and increase range of motion. Before our investigation, it was not known how long following an ultrasound treatment the tissue will remain at a vigorous heating level (>3°C). We conducted this study to determine the rate of temperature decay following 3 MHz ultrasound, in order to determine the time period of optimal stretching. Twenty subjects had a 23-gauge hypodermic needle microprobe inserted 1.2 cm deep into the medial aspect of their anesthetized triceps surae muscle. Subjects then received a 3 MHz ultrasound treatment at 1.5 W/cm2 until the tissue temperature was increased at least 5°C. The mean baseline temperature before each treatment was 33.8 ± 1.3°C, and it peaked at 39.1 ± 1.2°C from the ultrasound. Immediately following the treatment, we recorded the rate at which the temperature dropped at 30-second intervals. We ran a stepwise nonlinear regression analysis to predict temperature decay as a function of time following ultrasound treatment. We found a significant nonlinear relationship between time and temperature decay. The average time it took for the temperature to drop each degree as expressed in minutes and seconds was: 1°C = 1:20; 2°C = 3:22; 3°C = 5:50; 4°C = 9:13; 5°C = 14:55; 5.3°C = 18:00 (baseline). We conclude that under similar circumstances where the tissue temperature is raised 5°C, stretching will be effective, on average, for 3.3 minutes following an ultrasound treatment. To increase this stretching window, we suggest that stretching be applied during and immediately after ultrasound application. ImagesFig 1.Fig 2. PMID:16558352

  19. The effects of supramolecular assembly on exciton decay rates in organic semiconductors

    NASA Astrophysics Data System (ADS)

    Daniel, Clément; Makereel, François; Herz, Laura M.; Hoeben, Freek J. M.; Jonkheijm, Pascal; Schenning, Albertus P. H. J.; Meijer, E. W.; Friend, Richard H.; Silva, Carlos

    2005-08-01

    We present time-resolved photoluminescence measurements on two series of oligo-p-phenylenevinylene (OPV) materials that are functionalized with quadruple hydrogen-bonding groups. These form supramolecular assemblies with thermotropic reversibility. The morphology of the assemblies depends on the way that the oligomers are functionalized; monofunctionalized OPVs (MOPVs) form chiral, helical stacks while bifunctionalized OPVs (BOPVs) form less organized structures. These are therefore model systems to investigate the effects of supramolecular assembly, the effects of morphology, and the dependence of oligomer length on the radiative and nonradiative rates of π-conjugated materials. The purpose of this work is to use MOPV and BOPV derivatives as model systems to study the effect of intermolecular interactions on the molecular photophysics by comparing optical properties in the dissolved phase and the supramolecular assemblies. A simple photophysical analysis allows us to extract the intrinsic radiative and nonradiative decay rates and to unravel the consequences of interchromophore coupling with unprecedented detail. We find that interchromophore coupling strongly reduces both radiative and intrinsic nonradiative rates and that the effect is more pronounced in short oligomers.

  20. Pressure Decay Testing Methodology for Quantifying Leak Rates of Full-Scale Docking System Seals

    NASA Technical Reports Server (NTRS)

    Dunlap, Patrick H., Jr.; Daniels, Christopher C.; Wasowski, Janice L.; Garafolo, Nicholas G.; Penney, Nicholas; Steinetz, Bruce M.

    2010-01-01

    NASA is developing a new docking system to support future space exploration missions to low-Earth orbit and the Moon. This system, called the Low Impact Docking System, is a mechanism designed to connect the Orion Crew Exploration Vehicle to the International Space Station, the lunar lander (Altair), and other future Constellation Project vehicles. NASA Glenn Research Center is playing a key role in developing the main interface seal for this docking system. This seal will be relatively large with an outside diameter in the range of 54 to 58 in. (137 to 147 cm). As part of this effort, a new test apparatus has been designed, fabricated, and installed to measure leak rates of candidate full-scale seals under simulated thermal, vacuum, and engagement conditions. Using this test apparatus, a pressure decay testing and data processing methodology has been developed to quantify full-scale seal leak rates. Tests performed on untreated 54 in. diameter seals at room temperature in a fully compressed state resulted in leak rates lower than the requirement of less than 0.0025 lbm, air per day (0.0011 kg/day).

  1. Are there any agricultural effects on the capture rates of male euglossine bees (Apidae: Euglossini)?

    PubMed

    Sandino, Juan Carlos

    2004-03-01

    During 30 days male euglossine bees were bait-sampled at 12 sites, in the central Pacific coast of Colombia (ten days and four sites at each of three adjacent habitats: farmlands, highly disturbed forest and less disturbed forest) and 487 individuals were captured. Most captured individuals belonged to six species, five widely distributed through the American tropics and an endemic species. Two of the frequently captured species presented no different abundances between habitats, while the other four (67.97% of all the captured individuals), all of them big sized or long-tongued, were more frequently captured at the farmlands. A cluster analysis of the data matrix for the 23 captured species and the 12 sampling sites, grouped together the farmland sites, apart from the forest sites. It is proposed that male euglossine bees from generalist, long-tongued or big sized species, forage frequently at the farmlands, where fragrance or nectar resources may be clumped, less diverse, and present an access restricted by deep corollas or by microclimatic conditions of high temperature and low humidity. PMID:17357407

  2. A halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal

    SciTech Connect

    Blennow, Mattias; Herrero-Garcia, Juan; Schwetz, Thomas

    2015-05-21

    We show that a positive signal in a dark matter (DM) direct detection experiment can be used to place a lower bound on the DM capture rate in the Sun, independent of the DM halo. For a given particle physics model and DM mass we obtain a lower bound on the capture rate independent of the local DM density, velocity distribution, galactic escape velocity, as well as the scattering cross section. We illustrate this lower bound on the capture rate by assuming that upcoming direct detection experiments will soon obtain a significant signal. When comparing the lower bound on the capture rate with limits on the high-energy neutrino flux from the Sun from neutrino telescopes, we can place upper limits on the branching fraction of DM annihilation channels leading to neutrinos. With current data from IceCube and Super-Kamiokande non-trivial limits can be obtained for spin-dependent interactions and direct annihilations into neutrinos. In some cases also annihilations into ττ or bb start getting constrained. For spin-independent interactions current constraints are weak, but they may become interesting for data from future neutrino telescopes.

  3. Relationship between mosquito (Diptera: Culicidae) landing rates on a human subject and numbers captured using CO2-baited light traps

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Capture rates of female Aedes albopictus Skuse, Aedes triseriatus (Say), Anopheles quadrimaculatus Say, Culex nigripalpus Theobald, and Culex quinquefasciatus Say in CDC-type light traps supplemented with CO2 (LT) and using the human landing (HL) collection method were observed in matched-pair exper...

  4. Neutron capture studies: 1, Multiple capture reactions and implications for calculated beta-delayed fission rates: 2, The nuclear level structure of 238Np

    SciTech Connect

    Hoff, R.W.

    1988-02-19

    Astrophysical r-process calculations of transbismuth elements are of interest because certain actinide pairs can be treated as chronometers in determining the duration of nucleosynthesis. For one such calculation where a particularly long galactic age was derived, 21 + 2 - 4 Gyr, we present evidence that the effect of beta-delayed fission appears to be seriously overestimated in uranium decay chains with A = 252 to 257. With this conclusion, it follows that this estimate of the galactic age must be considered more uncertain than if the calculated rates of beta-delayed fission were found to be acceptable. The nuclear level structure of 238Np has been investigated using the 237Np(n,..gamma..)238Np reaction and the alpha decay of 242mAm as experimental probes. Having established a level scheme for 238Np that includes 47 excited levels and 93 secondary transitions, we find a high degree of correspondence between the experimental band structure and that of a semi-empirical model developed to predict excitations in odd-odd deformed nuclei. 35 refs., 4 figs., 3 tabs.

  5. Investigating the decay rates of Escherichia coli relative to Vibrio parahemolyticus and Salmonella Typhi in tropical coastal waters.

    PubMed

    Lee, Choon Weng; Ng, Angie Yee Fang; Bong, Chui Wei; Narayanan, Kumaran; Sim, Edmund Ui Hang; Ng, Ching Ching

    2011-02-01

    Using the size fractionation method, we measured the decay rates of Escherichia coli, Salmonella Typhi and Vibrio parahaemolyticus in the coastal waters of Peninsular Malaysia. The size fractions were total or unfiltered, <250 μm, <20 μm, <2 μm, <0.7 μm, <0.2 μm and <0.02 μm. We also carried out abiotic (inorganic nutrients) and biotic (bacterial abundance, production and protistan bacterivory) measurements at Port Dickson, Klang and Kuantan. Klang had highest nutrient concentrations whereas both bacterial production and protistan bacterivory rates were highest at Kuantan. We observed signs of protist-bacteria coupling via the following correlations: Protistan bacterivory-Bacterial Production: r = 0.773, df = 11, p < 0.01; Protist-Bacteria: r = 0.586, df = 12, p < 0.05. However none of the bacterial decay rates were correlated with the biotic variables measured. E. coli and Salmonella decay rates were generally higher in the larger fraction (>0.7 μm) than in the smaller fraction (<0.7 μm) suggesting the more important role played by protists. E. coli and Salmonella also decreased in the <0.02 μm fraction and suggested that these non-halophilic bacteria did not survive well in seawater. In contrast, Vibrio grew well in seawater. There was usually an increase in Vibrio after one day incubation. Our results confirmed that decay or loss rates of E. coli did not match that of Vibrio, and also did not correlate with Salmonella decay rates. However E. coli showed persistence where its decay rates were generally lower than Salmonella. PMID:21146847

  6. Decay Rates and Semi-stable Fraction Formation after 12 years of Foliar Litter Decomposition in Canadian Forests

    NASA Astrophysics Data System (ADS)

    Trofymow, J. A.; Smyth, C.; Moore, T.; Prescott, C.; Titus, B.; Siltanen, M.; Visser, S.; Preston, C. M.; Nault, J.

    2009-12-01

    Litter decay in early and midphases of decomposition have been shown to highly influenced by climate and substrate quality, however factors affecting decay during the late semi-stable phase are less well understood. The Canadian Intersite Decomposition Experiment (CIDET) was established in 1992 with the objective of providing data on the long-term rates of litter decomposition and nutrient mineralization for a range of forested ecoclimatic regions in Canada. Such data were needed to help verify models used for national C accounting, as well as aid in the development of other soil C models. CIDET examined the annual decay, over a 12-year period, of 10 standard foliar litters and 2 wood substrates at 18 forested upland and 3 wetland sites ranging from the cool temperate to subarctic regions, a nearly 20oC span in temperature. On a subset of sites and litter types, changes in litter C chemistry over time were also determined. Over the first 6 years, C/N ratio and iron increased, NMR showed an overall decline in O-alkyl C (carbohydrates) and increase in alkyl, aromatic, phenolic, and carboxyl C. Proximate analysis showed the acid unhydrolyzable residue (AUR) increases, but true lignin did not accumulate, in contrast to the conceptual ligno-cellulose model of decomposition. Litter decay during first phase was related to initial litter quality (AUR and water soluble extract), winter precipitation, but not temperature, suggesting the importance of leaching during this phase. Decay rate “k” during the mid phase was related to temperature, initial litter quality (AUR and AUR/N), summer precipitation, but not soil N. In most cases decay had approached an asymptote before end of experiment. Although annual temperature was the best single predictor for 12-year asymptotes, summer precipitation and forest floor pH and C/N ratio were the best set of combined predictors. The changes in the decay factors during different phases may explain some of the discrepancies in the

  7. A Pilot Study of Mood Ratings Captured by Mobile Phone Versus Paper-and-Pencil Mood Charts in Bipolar Disorder

    PubMed Central

    Depp, Colin A.; Kim, Daniel H.; de Dios, Laura Vergel; Wang, Vicki; Ceglowski, Jennifer

    2013-01-01

    Objective Patient reported mood charts are frequently used in management of bipolar disorder. Although mood charts have recently been programmed in electronic devices such as mobile phones, little is known about the impact of the method of data capture on the psychometric properties and validity of these data. Methods In an ongoing pilot study, a sample of outpatients with bipolar disorder were randomized to either complete mood charts on a mobile phone or a standard paper-and-pencil mood chart as part of a 12 week-intervention (primary outcomes for the trial await study completion). We compared these conditions across single item rating of mood state, and we hypothesized that mobile phone based data capture would produce greater compliance to mood ratings, variability between and within participants, and concurrent validity with blinded clinician-rated affective symptom severity. Results A total of 56 participants were randomized and 40 participants were included in the analyses. There were no significant differences between conditions on demographic or clinical variables. The rate of compliance was significantly higher in paper-and-pencil versus mobile phone ratings. Ratings demonstrated significantly more variability within individuals in the mobile phone condition. Mobile phone mood ratings were significantly correlated with clinician-rated depressive symptom severity across the study and with manic symptom severity at the Week 6 assessment, whereas paper-and-pencil ratings were not significantly associated with clinician-rated depression or mania. Conclusions Although preliminary, our results suggest a lower rate of compliance with mobile phones compared to paper-and-pencil daily mood rating in bipolar disorder, yet a greater ability to capture variability and concurrent validity in quantifying affective symptoms. This clinical trial is registered at http://www.clinicaltrials.gov as NCT01670123. PMID:23646035

  8. Spin-dependent energy distribution of B-hadrons from polarized top decays considering the azimuthal correlation rate

    NASA Astrophysics Data System (ADS)

    Moosavi Nejad, S. M.

    2016-04-01

    Basically, the energy distribution of bottom-flavored hadrons produced through polarized top quark decays t (↑) →W+ + b (→Xb), is governed by the unpolarized rate and the polar and the azimuthal correlation functions which are related to the density matrix elements of the decay t (↑) → bW+. Here we present, for the first time, the analytical expressions for the O (αs) radiative corrections to the differential azimuthal decay rates of the partonic process t (↑) → b +W+ in two helicity systems, which are needed to study the azimuthal distribution of the energy spectrum of the hadrons produced in polarized top decays. These spin-momentum correlations between the top quark spin and its decay product momenta will allow the detailed studies of the top decay mechanism. Our predictions of the hadron energy distributions also enable us to deepen our knowledge of the hadronization process and to test the universality and scaling violations of the bottom-flavored meson fragmentation functions.

  9. Approaches for the direct estimation of rate of increase in population size using capture-recapture data

    USGS Publications Warehouse

    Nichols, J.D.; Sillett, T. Scott; Hines, J.E.; Holmes, Richard T.

    2005-01-01

    Recent developments in the modeling of capture-recapture data permit the direct estimation and modeling of population growth rate Pradel (1996). Resulting estimates reflect changes in numbers of birds on study areas, and such changes result from movement as well as survival and reproductive recruitment. One measure of the 'importance' of a demographic vital rate to population growth is based on temporal covariation (i.e., do changes in population growth follow changes in vital rates). If data are available to estimate vital rates or their components, then such data can be combined with capture-recapture data in order to estimate parameters of the relationship between population growth and the vital rate. These methods are illustrated using capture-recapture and nest observation data for Black-throated Blue Warblers, Dendroica caerulescens, from a long-term study at Hubbard Brook Experimental Forest, New Hampshire, USA. Population growth rate was found to be positively associated with the proportion of birds that double-brood. We encourage use of these methods and believe they will prove to be very useful in research on, and management of, migratory bird populations.

  10. Low lying states in {sup 153}Ho and {sup 157}Tm from electron capture and {beta}{sup +} decay of {sup 153}Er and {sup 157}Yb

    SciTech Connect

    Xu, S.; Xie, Y.; Pan, Q.; Luo, Y.; Zhang, C.; Zhang, J.; Wang, Y.; Zhang, X.; Gu, J.; Ge, Y.; Yin, X.; Wang, C.; Xing, Z.; Chen, X.

    1996-09-01

    A detailed discussion and supplemental experimental information on the electron capture and {beta}{sup +} decay schemes of {sup 153}Er and {sup 157}Yb proposed in our previous publications are included. The three-quasiparticle state and single-proton states assigned to {sup 153}Ho have been reproduced by a shell model calculation. The extracted quenching factor for the three-quasiparticle state was determined to be 10. The existence of the two bands in {sup 157}Tm has been explained by a triaxial deformation of the ground state of this nucleus. The experimental evidence from systematic behavior of the compiled low-energy levels indicates that the ground-state shapes change from spherical to deformed between neutron numbers {ital N}=86 and 88 in both the odd Ho and odd Tm isotopic chains. {copyright} {ital 1996 The American Physical Society.}

  11. A coupled deterministic/stochastic method for computing neutron capture therapy dose rates

    NASA Astrophysics Data System (ADS)

    Hubbard, Thomas Richard

    Neutron capture therapy (NCT) is an experimental method of treating brain tumors and other cancers by: (1) injecting or infusing the patient with a tumor-seeking, neutron target-labeled drug; and (2) irradiating the patient in an intense epithermal neutron fluence. The nuclear reaction between the neutrons and the target nuclei (e.g. sp{10}B(n,alpha)sp7Lirbrack releases energy in the form of high-LET (i.e. energy deposited within the range of a cell diameter) reaction particles which selectively kill the tumor cell. The efficacy of NCT is partly dependent on the delivery of maximum thermal neutron fluence to the tumor and the minimization of radiation dose to healthy tissue. Since the filtered neutron source (e.g. research reactor) usually provides a broad energy spectrum of highly-penetrating neutron and gamma-photon radiation, detailed transport calculations are necessary in order to plan treatments that use optimal treatment facility configurations and patient positioning. Current computational methods for NCT use either discrete ordinates calculation or, more often, Monte Carlo simulation to predict neutron fluences in the vicinity of the tumor. These methods do not, however, accurately calculate the transport of radiation throughout the entire facility or the deposition of dose in all the various parts of the body due to shortcomings of using either method alone. A computational method, specifically designed for NCT problems, has been adapted from the MASH methodology and couples a forward discrete ordinates (Ssb{n}) calculation with an adjoint Monte Carlo run to predict the dose at any point within the patient. The transport from the source through the filter/collimator is performed with a forward DORT run, and this is then coupled to adjoint MORSE results at a selected coupling parallelepiped which surrounds human phantom. Another routine was written to allow the user to generate the MORSE models at various angles and positions within the treatment room. The

  12. Modification of magicity toward the dripline and its impact on electron-capture rates for stellar core collapse

    NASA Astrophysics Data System (ADS)

    Raduta, Ad. R.; Gulminelli, F.; Oertel, M.

    2016-02-01

    The importance of microphysical inputs from laboratory nuclear experiments and theoretical nuclear structure calculations in the understanding of core-collapse dynamics and the subsequent supernova explosion is largely recognized in the recent literature. In this work, we analyze the impact of the masses of very neutron-rich nuclei on the matter composition during collapse and the corresponding electron-capture rate. To this end, we introduce an empirical modification of the popular Duflo-Zuker mass model to account for possible shell quenching far from stability. We study the effect of this quenching on the average electron-capture rate. We show that the pre-eminence of the closed shells with N =50 and N =82 in the collapse dynamics is considerably decreased if the shell gaps are reduced in the region of 78Ni and beyond. As a consequence, local modifications of the overall electron-capture rate of up to 30% can be expected, depending on the strength of magicity quenching. This finding has potentially important consequences on the entropy generation, the neutrino emissivity, and the mass of the core at bounce. Our work underlines the importance of new experimental measurements in this region of the nuclear chart, the most crucial information being the nuclear mass and the Gamow-Teller strength. Reliable microscopic calculations of the associated elementary rate, in a wide range of temperatures and electron densities, optimized on these new empirical information, will be additionally needed to get quantitative predictions of the collapse dynamics.

  13. Probing Anderson localization of light via decay rate statistics in aperiodic Vogel spirals

    NASA Astrophysics Data System (ADS)

    Christofi, Aristi; Pinheiro, Felipe A.; Dal Negro, Luca

    We systematically investigate the spectral properties of different types of two-dimensional aperiodic Vogel spiral arrays of pointlike scatterers and three-dimensional metamaterials with Vogel spiral chirality using rigorous Green's function spectral method. We considered an efficient T-matrix approach to analyze multiple-scattering effects, including all scattering orders, and to understand localization properties through the statistics of the Green's matrix eigenvalues. The knowledge of the spectrum of the Green matrix of multi-particle scattering systems provides important information on the character of light propagation and localization in chiral media with deterministic aperiodic geometry. In particular, we analyze for the first time the statistics of the eigenvalues and eigenvectors of the Green matrix and extract the decay rates of the eigenmodes, their inverse participation ratio (IPR), the Wigner delay times and their quality factors. We emphasize the unique properties of aperiodic Vogel spirals with respect to random scattering media, which have been investigated so far. This work was supported by the Army Research Laboratory under Cooperative Agreement Number W911NF-12-2-0023.

  14. Precision measurement of the decay rate of the negative positronium ion Ps{sup -}

    SciTech Connect

    Ceeh, Hubert; Hugenschmidt, Christoph; Schreckenbach, Klaus; Gaertner, Stefan A.; Thirolf, Peter G.; Fleischer, Frank; Schwalm, Dirk

    2011-12-15

    The negative positronium ion Ps{sup -} is a bound system consisting of two electrons and a positron. Its three constituents are pointlike leptonic particles of equal mass, which are subject only to the electroweak and gravitational force. Hence, Ps{sup -} is an ideal object in which to study the quantum mechanics of a three-body system. The ground state of Ps{sup -} is stable against dissociation but unstable against annihilation into photons. We report here on a precise measurement of the Ps{sup -} ground-state decay rate {Gamma}, which was carried out at the high-intensity NEutron induced POsitron source MUniCh (NEPOMUC) at the research reactor FRM II in Garching. A value of {Gamma}=2.0875(50) ns{sup -1} was obtained, which is three times more precise than previous experiments and in agreement with most recent theoretical predictions. The achieved experimental precision is at the level of the leading corrections in the theoretical predictions.

  15. Contributions of the W-boson propagator to the μ and τ leptonic decay rates

    NASA Astrophysics Data System (ADS)

    Ferroglia, Andrea; Greub, Christoph; Sirlin, Alberto; Zhang, Zhibai

    2013-08-01

    We derive closed expressions and useful expansions for the contributions of the tree-level W-boson propagator to the muon and τ leptonic decay rates. Calling M and m the masses of the initial and final charged leptons, our results in the limit m=0 are valid to all orders in M2/MW2. In the terms of O(mj2/MW2) (mj=M, m), our leading corrections, of O(M2/MW2), agree with the canonical value (3/5)M2/MW2, while the coefficient of our subleading contributions, of O(m2/MW2), differs from that reported in the recent literature. A possible explanation of the discrepancy is presented. The numerical effect of the O(mj2/MW2) corrections is briefly discussed. A general expression, valid for arbitrary values of MW, M, and m in the range MW>M>m, is given in the Appendix. The paper also contains a review of the traditional definition and evaluation of the Fermi constant.

  16. Minimally allowed neutrinoless double beta decay rates within an anarchical framework

    NASA Astrophysics Data System (ADS)

    Jenkins, James

    2009-06-01

    Neutrinoless double beta decay (ββ0ν) is the only realistic probe of the Majorana nature of the neutrino. In the standard picture, its rate is proportional to mee, the e-e element of the Majorana neutrino mass matrix in the flavor basis. I explore minimally allowed mee values within the framework of mass matrix anarchy where neutrino parameters are defined statistically at low energies. Distributions of mixing angles are well defined by the Haar integration measure, but masses are dependent on arbitrary weighting functions and boundary conditions. I survey the integration measure parameter space and find that for sufficiently convergent weightings, mee is constrained between (0.01-0.4) eV at 90% confidence. Constraints from neutrino mixing data lower these bounds. Singular integration measures allow for arbitrarily small mee values with the remaining elements ill-defined, but this condition constrains the flavor structure of the model’s ultraviolet completion. ββ0ν bounds below mee˜5×10-3eV should indicate symmetry in the lepton sector, new light degrees of freedom, or the Dirac nature of the neutrino.

  17. Minimally allowed neutrinoless double beta decay rates within an anarchical framework

    SciTech Connect

    Jenkins, James

    2009-06-01

    Neutrinoless double beta decay ({beta}{beta}0{nu}) is the only realistic probe of the Majorana nature of the neutrino. In the standard picture, its rate is proportional to m{sub ee}, the e-e element of the Majorana neutrino mass matrix in the flavor basis. I explore minimally allowed m{sub ee} values within the framework of mass matrix anarchy where neutrino parameters are defined statistically at low energies. Distributions of mixing angles are well defined by the Haar integration measure, but masses are dependent on arbitrary weighting functions and boundary conditions. I survey the integration measure parameter space and find that for sufficiently convergent weightings, m{sub ee} is constrained between (0.01-0.4) eV at 90% confidence. Constraints from neutrino mixing data lower these bounds. Singular integration measures allow for arbitrarily small m{sub ee} values with the remaining elements ill-defined, but this condition constrains the flavor structure of the model's ultraviolet completion. {beta}{beta}0{nu} bounds below m{sub ee}{approx}5x10{sup -3} eV should indicate symmetry in the lepton sector, new light degrees of freedom, or the Dirac nature of the neutrino.

  18. Using the Inflection Points and Rates of Growth and Decay to Predict Levels of Solar Activity

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    The ascending and descending inflection points and rates of growth and decay at specific times during the sunspot cycle are examined as predictors for future activity. On average, the ascending inflection point occurs about 1-2 yr after sunspot minimum amplitude (Rm) and the descending inflection point occurs about 6-7 yr after Rm. The ascending inflection point and the inferred slope (including the 12-mo moving average (12-mma) of (Delta)R (the month-to-month change in the smoothed monthly mean sunspot number (R)) at the ascending inflection point provide strong indications as to the expected size of the ongoing cycle s sunspot maximum amplitude (RM), while the descending inflection point appears to provide an indication as to the expected length of the ongoing cycle. The value of the 12-mma of (Delta)R at elapsed time T = 27 mo past the epoch of RM (E(RM)) seems to provide a strong indication as to the expected size of Rm for the following cycle. The expected Rm for cycle 24 is 7.6 +/- 4.4 (the 90-percent prediction interval), occurring before September 2008. Evidence is also presented for secular rises in selected cycle-related parameters and for preferential grouping of sunspot cycles by amplitude and/or period.

  19. Determination of plate wave velocities and diffuse field decay rates with braod-band acousto-ultrasonic signals

    NASA Technical Reports Server (NTRS)

    Kautz, Harold E.

    1993-01-01

    Lowest symmetric and lowest antisymmetric plate wave modes were excited and identified in broad-band acousto-ultrasonic (AU) signals collected from various high temperature composite materials. Group velocities have been determined for these nearly nondispersive modes. An algorithm has been developed and applied to determine phase velocities and hence dispersion curves for the frequency ranges of the broad-band pulses. It is demonstrated that these data are sensitive to changes in the various stiffness moduli of the materials, in agreement by analogy, with the theoretical and experimental results of Tang and Henneke on fiber reinforced polymers. Diffuse field decay rates have been determined in the same specimen geometries and AU configuration as for the plate wave measurements. These decay rates are of value in assessing degradation such as matrix cracking in ceramic matrix composites. In addition, we verify that diffuse field decay rates respond to fiber/matrix interfacial shear strength and density in ceramic matrix composites. This work shows that velocity/stiffness and decay rate measurements can be obtained in the same set of AU experiments for characterizing materials and in specimens with geometries useful for mechanical measurements.

  20. Decay rates of a molecule in the vicinity of a spherical surface of an isotropic magnetodielectric material

    NASA Astrophysics Data System (ADS)

    Chung, H. Y.; Leung, P. T.; Tsai, D. P.

    2012-10-01

    A comprehensive study is presented on the decay rates of excited molecules in the vicinity of a magnetodielectric material of spherical geometry via electrodynamic modeling. Both the models based on a driven-damped harmonic oscillator and on energy transfers will be applied so that the total decay rates can be rigorously decomposed into the radiative and the nonradiative rates. Clarifications of the equivalence of these two models for arbitrary geometry will be provided. Different possible orientations and locations of the molecule are studied with the molecule being placed near a spherical particle or a cavity. Among other results, TE modes are observed which can be manifested via nonradiative transfer from a tangential dipole within a small range of dissipation parameters set for the spherical particle. In addition, spectral analysis shows that decay rates at such a particle with small absorption are largely dominated by radiative transfer except at multipolar resonances when nonradiative transfer becomes prominent, and relatively unmodified decay is possible when negative refraction takes place.

  1. Viral abundance, production, decay rates and life strategies (lysogeny versus lysis) in Lake Bourget (France).

    PubMed

    Thomas, Rozenn; Berdjeb, Lyria; Sime-Ngando, Télesphore; Jacquet, Stéphan

    2011-03-01

    We have investigated the ecology of viruses in Lake Bourget (France) from January to August 2008. Data were analysed for viral and bacterial abundance and production, viral decay, frequency of lysogenic cells, the contribution of bacteriophages to prokaryotic mortality and their potential influence on nutrient dynamics. Analyses and experiments were conducted on samples from the epilimnion (2 m) and the hypolimnion (50 m), taken at the reference site of the lake. The abundance of virus-like particles (VLP) varied from 3.4 × 10⁷to 8.2 × 10⁷ VLP ml⁻¹; with the highest numbers and virus-to-bacterium ratio (VBR = 69) recorded in winter. Viral production varied from 3.2 × 10⁴ VLP ml⁻¹  h⁻¹ (July) to 2 × 10⁶ VLP ml⁻¹ h⁻¹ (February and April), and production was lower in the hypolimnion. Viral decay rate reached 0.12-0.15 day⁻¹, and this parameter varied greatly with sampling date and methodology (i.e. KCN versus filtration). Using transmission electron microscopy (TEM) analysis, viral lysis was responsible for 0% (January) to 71% (February) of bacterial mortality, while viral lysis varied between 0% (April) and 53% (January) per day when using a modified dilution approach. Calculated from viral production and burst size, the virus-induced bacterial mortality varied between 0% (January) and 68% (August). A weak relationship was found between the two first methods (TEM versus dilution approach). Interestingly, flow cytometry analysis performed on the dilution experiment samples revealed that the viral impact was mostly on high DNA content bacterial cells whereas grazing, varying between 8.3% (June) and 75.4% (April), was reflected in both HDNA and LDNA cells equally. The lysogenic fraction varied between 0% (spring/summer) and 62% (winter) of total bacterial abundance, and increased slightly with increasing amounts of mitomycin C added. High percentages of lysogenic cells were recorded when bacterial abundance and activity were the lowest

  2. Exact evaluation of the rates of electrostatic decay and scattering off thermal ions for an unmagnetized Maxwellian plasma

    SciTech Connect

    Layden, B.; Cairns, Iver H.; Robinson, P. A.

    2013-08-15

    Electrostatic decay of Langmuir waves into Langmuir and ion sound waves (L→L′+S) and scattering of Langmuir waves off thermal ions (L+i→L′+i′, also called “nonlinear Landau damping”) are important nonlinear weak-turbulence processes. The rates for these processes depend on the quadratic longitudinal response function α{sup (2)} (or, equivalently, the quadratic longitudinal susceptibility χ{sup (2)}), which describes the second-order response of a plasma to electrostatic wave fields. Previous calculations of these rates for an unmagnetized Maxwellian plasma have relied upon an approximate form for α{sup (2)} that is valid where two of the wave fields are fast (i.e., v{sub φ}=ω/k≫V{sub e} where ω is the angular frequency, k is the wavenumber, and V{sub e} is the electron thermal speed) and one is slow (v{sub φ}≪V{sub e}). Recently, an exact expression was derived for α{sup (2)} that is valid for any phase speeds of the three waves in an unmagnetized Maxwellian plasma. Here, this exact α{sup (2)} is applied to the calculation of the three-dimensional rates for electrostatic decay and scattering off thermal ions, and the resulting exact rates are compared with the approximate rates. The calculations are performed using previously derived three-dimensional rates for electrostatic decay given in terms of a general α{sup (2)}, and newly derived three-dimensional rates for scattering off thermal ions; the scattering rate is derived assuming a Maxwellian ion distribution, and both rates are derived assuming arc distributions for the wave spectra. For most space plasma conditions, the approximate rate is found to be accurate to better than 20%; however, for sufficiently low Langmuir phase speeds (v{sub φ}/V{sub e}≈3) appropriate to some spatial domains of the foreshock regions of planetary bow shocks and type II solar radio bursts, the use of the exact rate may be necessary for accurate calculations. The relative rates of electrostatic decay

  3. Rates of decay to non homogeneous Timoshenko model with tip body

    NASA Astrophysics Data System (ADS)

    Muñoz Rivera, Jaime E.; Ávila, Andrés I.

    2015-05-01

    We consider the uniform stabilization of a hybrid elastic model consisting of a Timoshenko beam and a tip load at the free end of the beam. Our main result proves that the semigroup eAt associated to this model is not exponentially stable. Moreover, we prove that the semigroup decays polynomially to zero as t - 1 / 2. When the damping mechanism is effective only on the boundary of the rotational angle, the solution also decays polynomially as t - 1 / 2 provided the wave speeds are equal. Otherwise it decays as t - 1 / 4 for any initial data taken in D (A).

  4. Decay rates of Gaussian-type I-balls and Bose-enhancement effects in 3+1 dimensions

    SciTech Connect

    Kawasaki, Masahiro; Yamada, Masaki E-mail: yamadam@icrr.u-tokyo.ac.jp

    2014-02-01

    I-balls/oscillons are long-lived spatially localized lumps of a scalar field which may be formed after inflation. In the scalar field theory with monomial potential nearly and shallower than quadratic, which is motivated by chaotic inflationary models and supersymmetric theories, the scalar field configuration of I-balls is approximately Gaussian. If the I-ball interacts with another scalar field, the I-ball eventually decays into radiation. Recently, it was pointed out that the decay rate of I-balls increases exponentially by the effects of Bose enhancement under some conditions and a non-perturbative method to compute the exponential growth rate has been derived. In this paper, we apply the method to the Gaussian-type I-ball in 3+1 dimensions assuming spherical symmetry, and calculate the partial decay rates into partial waves, labelled by the angular momentum of daughter particles. We reveal the conditions that the I-ball decays exponentially, which are found to depend on the mass and angular momentum of daughter particles and also be affected by the quantum uncertainty in the momentum of daughter particles.

  5. Decay rates of Gaussian-type I-balls and Bose-enhancement effects in 3+1 dimensions

    SciTech Connect

    Kawasaki, Masahiro; Yamada, Masaki

    2014-02-03

    I-balls/oscillons are long-lived spatially localized lumps of a scalar field which may be formed after inflation. In the scalar field theory with monomial potential nearly and shallower than quadratic, which is motivated by chaotic inflationary models and supersymmetric theories, the scalar field configuration of I-balls is approximately Gaussian. If the I-ball interacts with another scalar field, the I-ball eventually decays into radiation. Recently, it was pointed out that the decay rate of I-balls increases exponentially by the effects of Bose enhancement under some conditions and a non-perturbative method to compute the exponential growth rate has been derived. In this paper, we apply the method to the Gaussian-type I-ball in 3+1 dimensions assuming spherical symmetry, and calculate the partial decay rates into partial waves, labelled by the angular momentum of daughter particles. We reveal the conditions that the I-ball decays exponentially, which are found to depend on the mass and angular momentum of daughter particles and also be affected by the quantum uncertainty in the momentum of daughter particles.

  6. The effect of restoration of broken SU(4) symmetry on 2 νβ-β- decay rates

    NASA Astrophysics Data System (ADS)

    Ünlü, Serdar; Çakmak, Neçla

    2015-07-01

    The effect of restoration of SU(4) symmetry violations stemming from the mean field approximation on the 2 νβ-β- decay amplitudes and half-lives for 76Ge →76Se, 82Se →82Kr, 96Zr →96Mo and 100Mo →100Ru decay systems is investigated within the framework of the proton-neutron quasi-particle random phase approximation (pnQRPA) method. In this respect, the broken SU(4) symmetry property of the central quasi-particle mean field term is restored by using Pyatov's restoration method. In order to see the influence of restoration on the stability of the nuclear matrix element, the variation of the nuclear matrix element with particle-particle strength parameter is computed within and without restoration. The calculated decay rates within restoration are compared with the schematic and shell model estimates.

  7. Modelling the Effects of Prey Size and Distribution on Prey Capture Rates of Two Sympatric Marine Predators

    PubMed Central

    Thaxter, Chris B.; Daunt, Francis; Grémillet, David; Harris, Mike P.; Benvenuti, Silvano; Watanuki, Yutaka; Hamer, Keith C.; Wanless, Sarah

    2013-01-01

    Understanding how prey capture rates are influenced by feeding ecology and environmental conditions is fundamental to assessing anthropogenic impacts on marine higher predators. We compared how prey capture rates varied in relation to prey size, prey patch distribution and prey density for two species of alcid, common guillemot (Uria aalge) and razorbill (Alca torda) during the chick-rearing period. We developed a Monte Carlo approach parameterised with foraging behaviour from bird-borne data loggers, observations of prey fed to chicks, and adult diet from water-offloading, to construct a bio-energetics model. Our primary goal was to estimate prey capture rates, and a secondary aim was to test responses to a set of biologically plausible environmental scenarios. Estimated prey capture rates were 1.5±0.8 items per dive (0.8±0.4 and 1.1±0.6 items per minute foraging and underwater, respectively) for guillemots and 3.7±2.4 items per dive (4.9±3.1 and 7.3±4.0 items per minute foraging and underwater, respectively) for razorbills. Based on species' ecology, diet and flight costs, we predicted that razorbills would be more sensitive to decreases in 0-group sandeel (Ammodytes marinus) length (prediction 1), but guillemots would be more sensitive to prey patches that were more widely spaced (prediction 2), and lower in prey density (prediction 3). Estimated prey capture rates increased non-linearly as 0-group sandeel length declined, with the slope being steeper in razorbills, supporting prediction 1. When prey patches were more dispersed, estimated daily energy expenditure increased by a factor of 3.0 for guillemots and 2.3 for razorbills, suggesting guillemots were more sensitive to patchier prey, supporting prediction 2. However, both species responded similarly to reduced prey density (guillemot expenditure increased by 1.7; razorbill by 1.6), thus not supporting prediction 3. This bio-energetics approach complements other foraging models in predicting likely

  8. DNA decay rate in papyri and human remains from Egyptian archaeological sites.

    PubMed

    Marota, Isolina; Basile, Corrado; Ubaldi, Massimo; Rollo, Franco

    2002-04-01

    The writing sheets made with strips from the stem (caulis) of papyri (Cyperus papyrus) are one of the most ingenious products of ancient technology. We extracted DNA from samples of modern papyri varying in age from 0-100 years BP and from ancient specimens from Egypt, with an age-span from 1,300-3,200 years BP. The copy number of the plant chloroplast DNA in the sheets was determined using a competitive PCR system designed on the basis of a short (90 bp) tract of the chloroplast's ribulose bisphosphate carboxylase large subunit (rbcL) gene sequence. The results allowed us to establish that the DNA half-life in papyri is about 19-24 years. This means that the last DNA fragments will vanish within no more than 532-672 years from the sheets being manufactured. In a parallel investigation, we checked the archaeological specimens for the presence of residual DNA and determined the extent of racemization of aspartic (Asp) acid in both modern and ancient specimens, as a previous report (Poinar et al. [1996], Science 272:864-866) showed that racemization of aspartic acid and DNA decay are linked. The results confirmed the complete loss of authentic DNA, even in the less ancient (8th century AD) papyri. On the other hand, when the regression for Asp racemization rates in papyri was compared with that for human and animal remains from Egyptian archaeological sites, it proved, quite surprisingly, that the regressions are virtually identical. Our study provides an indirect argument against the reliability of claims about the recovery of authentic DNA from Egyptian mummies and bone remains. PMID:11920366

  9. Estimating Suicide Rates in Developing Nations: A Low-Cost Newspaper Capture-Recapture Approach in Cambodia.

    PubMed

    Harris, Keith M; Thandrayen, Joanne; Samphoas, Chien; Se, Pros; Lewchalermwongse, Boontriga; Ratanashevorn, Rattanakorn; Perry, Megan L; Britts, Choloe

    2016-04-01

    This study tested a low-cost method for estimating suicide rates in developing nations that lack adequate statistics. Data comprised reported suicides from Cambodia's 2 largest newspapers. Capture-recapture modeling estimated a suicide rate of 3.8/100 000 (95% CI = 2.5-6.7) for 2012. That compares to World Health Organization estimates of 1.3 to 9.4/100 000 and a Cambodian government estimate of 3.5/100 000. Suicide rates of males were twice that of females, and rates of those <40 years were twice that of those ≥40 years. Capture-recapture modeling with newspaper reports proved a reasonable method for estimating suicide rates for countries with inadequate official data. These methods are low-cost and can be applied to regions with at least 2 newspapers with overlapping reports. Means to further improve this approach are discussed. These methods are applicable to both recent and historical data, which can benefit epidemiological work, and may also be applicable to homicides and other statistics. PMID:26969636

  10. Capture rates of the European pine sawfly, Neodiprion sertifer, in pheromone traps, with special regard to effects of wind speed.

    PubMed

    Ostrand, F; Anderbrant, O; Jönsson, P; Lyytikäinen-Saarenmaa, P

    2001-08-01

    Males of the European pine sawfly, Neodiprion sertifer Geoffr., were marked and released downwind from pheromone traps, baited with 100 micrograms of the sex pheromone (2S,3S,7S)-3,7-dimethyl-2-pentadecyl acetate. Males were released 5 m downwind from one trap, or downwind from five traps, 50 m or 200 m away. The average capture rates after 24 hr were 21.5%, 17.7% and 3.8%, respectively. The capture rate was highest at moderate wind speeds (1-2 m/sec) in the 50 m experiments, whereas it decreased above wind speeds of 1.5 m/sec in the 200 m experiments. With no precipitation and > 13.5 degrees C during overcast, wind speed is presumably the most important climatic factor for N. sertifer males flying upwind to a pheromone source. Travel time, the elapsed time form take-off to landing on the trap, varied considerably, and the shortest recorded travel times were 1, 6 and 45 min for the 5, 50, and 200 m experiments, respectively. The trap efficiency i.e., number of captured males per number of males that landed on the trap, was estimated at 52% in the 5 m experiments. The sampling range after 24 hr was calculated at approximately 400 m by regression analysis. The combination of the males' flight ability during upwind progress and their longevity (12 days), suggests a potentially large seasonal sampling range of the traps used in this study. PMID:11521396