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1

Reaction Mechanisms of the Proton - Deuteron Breakup Process at GeV Energies  

E-print Network

The deuteron fragmentation by fast protons has been studied both near the kinematics of quasi-free proton - proton scattering and far away from it. We have concentrated on the interplay between different reaction mechanisms associated with the antisymmetrization of the initial and final states and rescattering contributions. A multiple-scattering-expansion technique has been applied to evaluate the reaction amplitude. An essential element of this approach in the momentum representation is the use of the effective nucleon- nucleon interaction constructed by Love and Franey as a two-body t-matrix for the incident proton scattering on a bound nucleon in the deuteron. Along with the five-fold cross sections, the proton analyzing power and the deuteron analyzing powers have been calculated as function of the momentum of the outgoing fast proton. The results are compared with the data obtained by the Gatchina-Saclay collaboration.

N. B. Ladygina; A. V. Shebeko

2003-05-30

2

Breakup of deuterons on tritons  

NASA Astrophysics Data System (ADS)

The breakup reaction T ( d, p) nt at the projectile deuteron energy of 36.9 MeV was studied theoretically and experimentally. The measured inclusive spectra and angular distributions of product protons are presented. A theoretical description of the reaction in question is based on the microscopic nuclear-diffractionmodel and on the theory of resonance processes. It is shown that, in T ( d, p) processes, a significant role is played not only by quasifree processes involving final-state interaction that are considered in the diffraction approximation but also by the production of 4H* and 4He* resonance states. The experimental results obtained in the present study for the angular and energy distributions of final-state particles can be satisfactorily interpreted with allowance for these resonances. It is shown that only upon taking into account two 4H* resonances do the calculated spectra of protons from T ( d, p) reactions appear to be in good numerical agreement with experimental data.

Beliuskina, O. O.; Grantsev, V. I.; Kisurin, K. K.; Omelchuk, S. E.; Roznyuk, Yu. S.; Rudenko, B. A.; Semenov, V. S.; Slusarenko, L. I.; Struzhko, B. G.; Tartakovsky, V. K.

2012-12-01

3

Investigation of the intermediate-energy deuteron breakup reaction  

SciTech Connect

The Udagawa-Tamura formalism is employed to calculate the proton singles both in the bound and unbound regions. Both the Elastic-Breakup (EB) and the Breakup-Fusion (BF) processes are considered to calculate the doubly-differential cross section for light and intermediate mass nuclei. The calculated spectra for 25 and 56 MeV deuterons reproduce the experimental spectra very well except for the spectra at large angle and at low energies, of the outgoing particle. Contributions due to precompound and evaporation processes are estimated to supplement the spectral results based on the Elastic-Breakup and Breakup-Fusion mechanisms. An extension of the model calculations to higher deuteron energies is being made to test the (EB + BF) model limitations. 5 refs., 1 fig.

Divadeenam, M.; Ward, T.E.; Mustafa, M.G.; Udagawa, T.; Tamura, T.

1989-01-01

4

The Polarized Deuteron Breakup Experiment at COSY  

NASA Astrophysics Data System (ADS)

A study of the deuteron breakup reaction pd ? (pp)n with forward emission of a fast proton pair with small excitation energy Epp < 3 MeV has been performed using the ANKE spectrometer at COSY Jülich. The differential cross section of the breakup reaction, averaged up to 8° over the cm polar angle of the total momentum of the pp pairs, has been obtained at six proton beam energies Tp = 0.6, 0.7, 0.8, 0.95, 1.35, and 1.9 GeV. A first measurement of the vector analyzing power Ayp has been carried out, using a polarization normalization obtained with the EDDA detector. In addition, for the first time asymmetries of p?d elastic scattering at Tp = 500 MeV have been recorded with the spectator setup at ANKE.

Rathmann, F.; Barsov, S.; Dymov, S.; Kacharava, A.; Khoukaz, A.; Komarov, V.; Kulikov, A.; Kurbatov, A.; Lang, N.; Lehmann, I.; Lorentz, B.; Macharashvili, G.; Mussgiller, A.; Paetz gen. Schieck, H.; Schleichert, R.; Seyfarth, H.; Steffens, E.; Ströher, H.; Uzikov, Yu.; Yaschenko, S.; Zalikhanov, B.

2003-07-01

5

Hard breakup of the deuteron into two Delta-isobars  

E-print Network

We study high energy photodisintegration of the deuteron into two $\\Delta$-isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks the quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of $pn\\rightarrow \\Delta\\Delta$ scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the $pn\\rightarrow \\Delta\\Delta$ scattering. We predict that the cross section of the deuteron breakup to $ \\Delta^{++}\\Delta^{-}$ is 4-5 times larger than that of the breakup to the $ \\Delta^{+}\\Delta^{0}$ channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard $\\Delta$-isobars are the result of the disintegration of the preexisting $\\Delta\\Delta$ components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both $ \\Delta^{++}\\Delta^{-}$ and $ \\Delta^{+}\\Delta^{0}$ channels to be similar.

Carlos G. Granados; Misak M. Sargsian

2011-04-20

6

Hard breakup of the deuteron into two ? isobars  

NASA Astrophysics Data System (ADS)

We study high-energy photodisintegration of the deuteron into two ? isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks a quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn??? scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the pn??? scattering. We predict that the cross section of the deuteron breakup to ?++?- is 4-5 times larger than that of the breakup to the ?+?0 channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard ? isobars are the result of the disintegration of the preexisting ?? components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both ?++?- and ?+?0 channels to be similar.

Granados, Carlos G.; Sargsian, Misak M.

2011-05-01

7

Hard breakup of the deuteron into two ? -isobars  

NASA Astrophysics Data System (ADS)

Photodisintegration of the deuteron into two ?-isobars at large center of mass angles is studied within the QCD hard rescattering model (HRM). According to the HRM, the reaction proceeds in three main steps: the photon knocks the quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons emerging at large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn->?? scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. We predict that the cross section of the deuteron breakup to &++circ;&-circ; is 4-5 times larger than that of the breakup to the &+circ;0? channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard ?-isobars are the result of the disintegration of initial ?? components of the deuteron wave function. In this case, the angular distributions and cross sections of the breakup in both &++circ;&-circ; and &+circ;0? channels are expected to be similar.

Granados, Carlos; Sargsian, Misak

2011-04-01

8

Hard breakup of the deuteron into two {Delta} isobars  

SciTech Connect

We study high-energy photodisintegration of the deuteron into two {Delta} isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks a quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn{yields}{Delta}{Delta} scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the pn{yields}{Delta}{Delta} scattering. We predict that the cross section of the deuteron breakup to {Delta}{sup ++}{Delta}{sup -} is 4-5 times larger than that of the breakup to the {Delta}{sup +}{Delta}{sup 0} channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard {Delta} isobars are the result of the disintegration of the preexisting {Delta}{Delta} components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both {Delta}{sup ++}{Delta}{sup -} and {Delta}{sup +}{Delta}{sup 0} channels to be similar.

Granados, Carlos G.; Sargsian, Misak M. [Florida International University, Miami, Florida 33199 (United States)

2011-05-15

9

Hard breakup of the deuteron into two $\\Delta$-isobars  

E-print Network

We study high energy photodisintegration of the deuteron into two $\\Delta$-isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM the process develops in three main steps: the photon knocks the quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons produced at large transverse momenta. Within the HRM the cross section is expressed through the amplitude of $pn\\rightarrow \\Delta\\Delta$ scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the $pn\\rightarrow \\Delta\\Delta$ scattering. We predict a cross section for the deuteron breakup to $ \\Delta^{++}\\Delta^{-}$ a factor of 4-5 times larger than that for the breakup to the $ \\Delta^{-}...

Granados, Carlos G

2010-01-01

10

Neutrino Emissivities from Deuteron-Breakup and Formation in Supernovae  

NASA Astrophysics Data System (ADS)

Recently it was pointed out that there are abundant light clusters, such as deuteron, triton and helium, in supernova environment. An interesting question is how much neutrino emissions from these light clusters affect supernova explosion mechanism. To address this question through a supernova simulation, neutrino emissivities from these light clusters are necessary input. The deuteron is the simplest cluster, and occupy a substantial portion of the light cluster abundance. Thus in this work, we study neutrino emissions from electron/positron capture on the deuteron and the nucleon-nucleon fusion processes in the surface region of a supernova core. We evaluate these weak processes using one-nucleon impulse current supplemented by two-nucleon exchange-currents, and nuclear wave functions generated by a high precision nucleon-nucleon potential. We present the neutrino emissivities from the deuteron calculated for typical profiles of core-collapsed supernovae. These novel neutrino emissivities are compared with the standard neutrino emission mechanisms.

Nakamura, Satoshi X.

2014-12-01

11

Quark-Model Baryon-Baryon Interaction Applied to Neutron-Deuteron Scattering. III - - Breakup Differential Cross Sections  

NASA Astrophysics Data System (ADS)

The low-energy breakup differential cross sections of the neutron-deuteron (nd) scattering are studied employing the energy-independent version of the quark-model baryon-baryon interaction fss2. This interaction reproduces almost all the breakup differential cross sections predicted by the meson-exchange potentials for neutron incident energies E_n ? 65 MeV. The space star anomaly of 13 MeV nd scattering is not improved even in our model. Some overestimation of the breakup differential cross sections at E_n = 22.7 -- 65 MeV implies that systematic studies of various breakup configurations are necessary both experimentally and theoretically.

Fujiwara, Y.; Fukukawa, K.

2011-05-01

12

Measurement of the reaction 2H(e,e') at 180 degrees close to the deuteron breakup threshold.  

PubMed

Inclusive inelastic electron scattering off the deuteron under 180 degrees has been studied at the S-DALINAC close to the breakup threshold at momentum transfers q=0.27 fm;{-1} and 0.74 fm;{-1} with good energy resolution sufficient to map in detail the spin flip M1 response, which governs the starting reaction pn-->dgamma of big-bang nucleosynthesis over most of the relevant temperature region. Results from potential model calculations and (for q=0.27 fm;{-1}) from pionless nuclear effective field theory are in excellent agreement with the data. PMID:18518283

Ryezayeva, N; Arenhövel, H; Burda, O; Byelikov, A; Chernykh, M; Enders, J; Griesshammer, H W; Kalmykov, Y; von Neumann-Cosel, P; Ozel, B; Poltoratska, I; Pysmenetska, I; Rangacharyulu, C; Rathi, S; Richter, A; Schrieder, G; Shevchenko, A; Yevetska, O

2008-05-01

13

Measurement of the Reaction {sup 2}H(e,e{sup '}) at 180 deg. Close to the Deuteron Breakup Threshold  

SciTech Connect

Inclusive inelastic electron scattering off the deuteron under 180 deg. has been studied at the S-DALINAC close to the breakup threshold at momentum transfers q=0.27 fm{sup -1} and 0.74 fm{sup -1} with good energy resolution sufficient to map in detail the spin flip M1 response, which governs the starting reaction pn{yields}d{gamma} of big-bang nucleosynthesis over most of the relevant temperature region. Results from potential model calculations and (for q=0.27 fm{sup -1}) from pionless nuclear effective field theory are in excellent agreement with the data.

Ryezayeva, N.; Burda, O.; Byelikov, A.; Chernykh, M.; Enders, J.; Kalmykov, Y.; Neumann-Cosel, P. von; Poltoratska, I.; Pysmenetska, I.; Rathi, S.; Richter, A.; Schrieder, G.; Shevchenko, A.; Yevetska, O. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Arenhoevel, H. [Institut fuer Kernphysik, Universitaet Mainz, D-55099 Mainz (Germany); Griesshammer, H. W. [Center for Nuclear Studies, Department of Physics, George Washington University, Washington, D.C. 20052 (United States); Oezel, B. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Science and Art Faculty, Cukurova University, 01330 Adana (Turkey); Rangacharyulu, C. [Department of Physics, University of Saskatchewan, Saskatoon, S7N 5E2 (Canada)

2008-05-02

14

Analysis of experimental data on doublet neutron-deuteron scattering at energies below the deuteron-breakup threshold on the basis of the pole approximation of the effective-range function  

NASA Astrophysics Data System (ADS)

On the basis of the Bargmann representation of the S matrix, the pole approximation is obtained for the effective-range function k cot ?. This approximation is optimal for describing the neutron-deuteron system in the doublet spin state. The values of r 0 = 412.469 fm and v 2 = -35 495.62 fm3 for the doublet low-energy parameters of neutron-deuteron scattering and the value of D = 172.678 fm2 for the respective pole parameter are deduced by using experimental results for the triton binding energy E T , the doublet neutron-deuteron scattering length a 2, and van Oers-Seagrave phase shifts at energies below the deuteron-breakup threshold. With these parameters, the pole approximation of the effective-range function provides a highly precise description (the relative error does not exceed 1%) of the doublet phase shift for neutron-deuteron scattering at energies below the deuteron-breakup threshold. Physical properties of the triton in the ground ( T) and virtual ( v) states are calculated. The results are B v = 0.608 MeV for the virtuallevel position and C {/T 2} = 2.866 and C {/v 2} = 0.0586 for the dimensionless asymptotic normalization constants. It is shown that, in the Whiting-Fuda approximation, the values of physical quantities characterizing the triton virtual state are determined to a high precision by one parameter, the doublet neutron-deuteron scattering length a 2. The effective triton radii in the ground ( ? T = 1.711 fm) and virtual ( ? v = 74.184 fm) states are calculated for the first time.

Babenko, V. A.; Petrov, N. M.

2008-01-01

15

Analysis of experimental data on doublet neutron-deuteron scattering at energies below the deuteron-breakup threshold on the basis of the pole approximation of the effective-range function  

SciTech Connect

On the basis of the Bargmann representation of the S matrix, the pole approximation is obtained for the effective-range function k cot {delta}. This approximation is optimal for describing the neutron-deuteron system in the doublet spin state. The values of r{sub 0} = 412.469 fm and v{sub 2} = -35 495.62 fm{sup 3} for the doublet low-energy parameters of neutron-deuteron scattering and the value of D = 172.678 fm{sup 2} for the respective pole parameter are deduced by using experimental results for the triton binding energy E{sub T}, the doublet neutron-deuteron scattering length a{sub 2}, and van Oers-Seagrave phase shifts at energies below the deuteron-breakup threshold. With these parameters, the pole approximation of the effective-range function provides a highly precise description (the relative error does not exceed 1%) of the doublet phase shift for neutron-deuteron scattering at energies below the deuteron-breakup threshold. Physical properties of the triton in the ground (T) and virtual (v) states are calculated. The results are B{sub v} = 0.608 MeV for the virtuallevel position and C{sub T}{sup 2} = 2.866 and C{sub v}{sup 2} = 0.0586 for the dimensionless asymptotic normalization constants. It is shown that, in the Whiting-Fuda approximation, the values of physical quantities characterizing the triton virtual state are determined to a high precision by one parameter, the doublet neutron-deuteron scattering length a{sub 2}. The effective triton radii in the ground ({rho}{sub T} = 1.711 fm) and virtual ({rho}{sub v} = 74.184 fm) states are calculated for the first time.

Babenko, V. A.; Petrov, N. M., E-mail: pet@online.com.ua [National Academy of Sciences of Ukraine, Bogolyubov Institute for Theoretical Physics (Ukraine)

2008-01-15

16

Review of quasi-elastic charge-exchange data in the nucleon-deuteron breakup reaction  

NASA Astrophysics Data System (ADS)

The available data on the forward charge exchange of nucleons on the deuteron up to 2 GeV/nucleon are reviewed. The value of the inclusive nd ? pnn/ np ? pn cross section ratio is sensitive to the fraction of spin-independent neutron-proton backward scattering. The measurements of the polarisation transfer in d( n, p){ nn} or the deuteron analysing power in p{ d, { pp}) n in high-resolution experiments, where the final nn or pp pair emerge at low excitation energy, depend upon the longitudinal and transverse spin-spin up amplitudes. The relation between these types of experiments is discussed and the results compared with predictions of the impulse approximation model in order to see what new constraints they can bring to the neutron-proton database.

Lehar, F.; Wilkin, C.

2010-07-01

17

Droplet Breakup Mechanisms in Air-blast Atomizers  

NASA Astrophysics Data System (ADS)

Atomization processes are encountered in many natural and man-made phenomena. Examples are pollen release by plants, human cough or sneeze, engine fuel injectors, spray paint and many more. The physics governing the atomization of liquids is important in understanding and utilizing atomization processes in both natural and industrial processes. We have observed the governing physics of droplet breakup in an air-blast water atomizer using a high magnification, high speed, and high resolution LASER imaging technique. The droplet breakup mechanisms are investigated in three major categories. First, the liquid drops are flattened to form an oblate ellipsoid (lenticular deformation). Subsequent deformation depends on the magnitude of the internal forces relative to external forces. The ellipsoid is converted into a torus that becomes stretched and disintegrates into smaller drops. Second, the drops become elongated to form a long cylindrical thread or ligament that break up into smaller drops (Cigar-shaped deformation). Third, local deformation on the drop surface creates bulges and protuberances that eventually detach themselves from the parent drop to form smaller drops.

Aliabadi, Amir Abbas; Taghavi, Seyed Mohammad; Lim, Kelly

2011-11-01

18

A PROPOSAL TO MEASURE THE CROSS SECTION OF THE SPACE STAR IN NEUTRON-DEUTERON BREAKUP IN A RECOIL GEOMETRY SETUP  

SciTech Connect

Nucleon-deuteron (Nd) breakup is an important tool for obtaining a better understanding of three-nucleon (3N) dynamics and for developing meson exchange descriptions of nuclear systems. The kinematics of the nd breakup reaction enable observables to be studied in a variety of exit-channel configurations that show sensitivity to realistic nucleon-nucleon (NN) potential models and three-nucleon force (3NF) models. Rigorous 3N calculations give very good descriptions of most 3N reaction data. However, there are still some serious discrepancies between data and theory. The largest discrepancy observed between theory and data for nd breakup is for the cross section for the space-star configuration. This discrepancy is known as the “Space star Anomaly”. Several experimental groups have obtained results consistent with the “Space Star Anomaly”, but it is important to note that they all used essentially the same experimental setup and so their experimental results are subject to the same systematic errors. We propose to measure the space-star cross-section at the Triangle Universities Nuclear Laboratory (TUNL) using an experimental technique that is significantly different from the one used in previous breakup experiments. This technique has been used by a research group from the University of Bonn to measure the neutron-neutron scattering length. There are three possible scenarios for the outcome of this work: 1) the new data are consistent with previous measurements; 2) the new data are not in agreement with previous measurements, but are in agreement with theory; and 3) the new data are not in agreement with either theory or previous measurements. Any one of the three scenarios will provide valuable insight on the Space Star Anomaly.

Benjamin J. Crowe III

2009-09-30

19

Direct processes effects on deuteron activation cross sections  

NASA Astrophysics Data System (ADS)

An extended analysis of reaction mechanisms involved in deuterons interaction with target nuclei from 27Al till 231Pa, at incident energies up to 60 MeV, is presented. Increased attention is devoted to direct processes, concerning the breakup, stripping, and pickup contributions to the deuteron activation cross sections. Finally, the pre-equilibrium and evaporation cross sections, corrected for the initial flux leakage towards direct processes, have completed the deuteron interaction analysis. The overall agreement of the measured data and model calculations proves the correctness of nuclear mechanism description.

Avrigeanu, M.; Avrigeanu, V.

2014-09-01

20

Systematic study of three-nucleon force effects in the cross section of the deuteron-proton breakup at 130 MeV  

SciTech Connect

High precision cross-section data of the deuteron-proton breakup reaction at 130 MeV are presented for 72 kinematically complete configurations. The data cover a large region of the available phase space, divided into a systematic grid of kinematical variables. They are compared with theoretical predictions, in which the full dynamics of the three-nucleon (3N) system is obtained in three different ways: realistic nucleon-nucleon (NN) potentials are combined with model 3N forces (3NF's) or with an effective 3NF resulting from explicit treatment of the Delta-isobar excitation. Alternatively, the chiral perturbation theory approach is used at the next-to-next-to-leading order with all relevant NN and 3N contributions taken into account. The generated dynamics is then applied to calculate cross-section values by rigorous solution of the 3N Faddeev equations. The comparison of the calculated cross sections with the experimental data shows a clear preference for the predictions in which the 3NF's are included. The majority of the experimental data points is well reproduced by the theoretical predictions. The remaining discrepancies are investigated by inspecting cross sections integrated over certain kinematical variables. The procedure of global comparisons leads to establishing regularities in disagreements between the experimental data and the theoretically predicted values of the cross sections. They indicate deficiencies still present in the assumed models of the 3N system dynamics.

St. Kistryn; E. Stephan; A. Biegun; K. Bodek; A. Deltuva; E. Epelbaum; K. Ermisch; W. Gloeckle; J. Golak; N. Kalantar-Nayestanaki; H. Kamada; M. Kis; B. Klos; A. Kozela; J. Kuros-Zolnierczuk; M. Mahjour-Shafiei; U.-G. Meissner; A. Micherdzinska; A. Nogga; P. U. Sauer; R. Skibinski; R. Sworst; H. Witala; J. Zejma; W. Zipper

2005-08-11

21

3D thermo-mechanical models of continental breakup and transition from rifting to continental break-up and spreading  

NASA Astrophysics Data System (ADS)

We conducted high-resolution 3D thermo-mechanical numerical modeling experiments to explore evolution and styles of plume-activated rifting in presence of preexisting far-field tectonic stress/strain field and tectonic heritage (in form of cratonic blocks embedded in «normal lithosphere»). The experiments demonstrate strong dependence of rifting style on preexisting far-field tectonic stress/strain field and initial thermo-rheological profile, as well as on the tectonic heritage. The models with homogeneous lithosphere demonstrate strongly non-linear impact of far-field extension rates on timing of break-up processes. Experiments with relatively fast far-field extension (6 mm/y) show intensive normal fault localization in crust and uppermost mantle above the zones of plume-head emplacement some 15-20 Myrs after the onset of the experiment. When plume head material reaches the bottom of the continental crust (at ~25 Myrs), the latter is rapidly ruptured (<1 Myrs) and several steady oceanic floor spreading centers develop. Slower (3 mm/y) far-field velocities result in disproportionally longer break-up time (from 60 to 70 Myrs depending on initial isoterm at the crust bottom). Although in all experiments with homogeneous lithosphere spreading centers have similar orientation perpendicular to the direction of far-field extension, their number and spatial location are different for different extension rates and thermo-rheological structures of the lithosphere. On the contrary, in case of normal lithosphere containing embedded cratonic block, spreading zones develop symmetrically, embracing cratonic micro-plate along its long sides. Presence of cratonic blocks leads to splitting of the plume head onto initially nearly symmetrical parts, each of which flows towards beneath the craton borders. This craton-controlled distribution of plume material causes the crustal strain localization and uprise of plume material along the craton boundaries. Though there is a net tendency, in all models, of more rapid transition to spreading in case of more intensive far-field forcing, the presence of «cratonic» blocks seemingly leads to certain «acceleration» of break-up processes. Thus, lithospheric heterogeneities play important role in spatial distribution of plume-induced spreading centers and in the timing of break-up processes.

Koptev, Alexander; Burov, Evgueni; Gerya, Taras

2014-05-01

22

Nuclear-breakup mechanisms in the interaction of relativistic projectiles with heavy targets  

SciTech Connect

The breakup of a Au nucleus under bombardment with relativistic p, ..cap alpha.., and /sup 20/Ne has been investigated in an extensive, multi-detector study. The present discussion addresses some of the many aspects of the experimental results. A broad distribution of coincident fragment masses is observed, with the total fragment kinetic energy being higher than expected for a fission mechanism for total fragment mass less than or equal to 120. The formation of light fragments is shown to be inconsistent with a binary breakup mechanism, and a multi-fragment target breakup is suggested. In general, the results indicate a broad spectrum of violence in the collisions, from gentle, leading to the production of heavy spallation products and fission, to essentially explosive, leading to multi-fragment breakup into light mas products. These aspects of the reactions represent a late-stage breakup of the target residues and are positively correlated with the violence of the initial fast stage of the collision as measured by the charged particle multiplicity.

Steinberg, E.P.

1982-01-01

23

Mechanism of Water Droplet Breakup near the Leading Edge of an Airfoil  

NASA Technical Reports Server (NTRS)

This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de T cnica Aeroespacial (INTA) in Madrid, Spain. The airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Droplet deformation is defined and studied against main parameters. The high speed imaging allowed observation of the actual mechanism of breakup and identification of the sequence of configurations from the initiation of the breakup to the disintegration of the droplet. Results and comparisons are presented for droplets of diameters in the range of 500 to 1800 micrometers, and airfoil velocities of 70 and 90 meters/second.

Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida Garcia

2012-01-01

24

Mechanism of Water Droplet Breakup Near the Leading Edge of an Airfoil  

NASA Technical Reports Server (NTRS)

This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. The airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Droplet deformation is defined and studied against main parameters. The high speed imaging allowed observation of the actual mechanism of breakup and identification of the sequence of configurations from the initiation of the breakup to the disintegration of the droplet. Results and comparisons are presented for droplets of diameters in the range of 500 to 1800 microns, and airfoil velocities of 70 and 90 m/sec.

Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida, Garcia

2012-01-01

25

Multiple mechanisms of spiral wave breakup in a model of cardiac electrical activity  

NASA Astrophysics Data System (ADS)

It has become widely accepted that the most dangerous cardiac arrhythmias are due to reentrant waves, i.e., electrical wave(s) that recirculate repeatedly throughout the tissue at a higher frequency than the waves produced by the heart's natural pacemaker (sinoatrial node). However, the complicated structure of cardiac tissue, as well as the complex ionic currents in the cell, have made it extremely difficult to pinpoint the detailed dynamics of these life-threatening reentrant arrhythmias. A simplified ionic model of the cardiac action potential (AP), which can be fitted to a wide variety of experimentally and numerically obtained mesoscopic characteristics of cardiac tissue such as AP shape and restitution of AP duration and conduction velocity, is used to explain many different mechanisms of spiral wave breakup which in principle can occur in cardiac tissue. Some, but not all, of these mechanisms have been observed before using other models; therefore, the purpose of this paper is to demonstrate them using just one framework model and to explain the different parameter regimes or physiological properties necessary for each mechanism (such as high or low excitability, corresponding to normal or ischemic tissue, spiral tip trajectory types, and tissue structures such as rotational anisotropy and periodic boundary conditions). Each mechanism is compared with data from other ionic models or experiments to illustrate that they are not model-specific phenomena. Movies showing all the breakup mechanisms are available at http://arrhythmia.hofstra.edu/breakup and at ftp://ftp.aip.org/epaps/chaos/E-CHAOEH-12-039203/ INDEX.html. The fact that many different breakup mechanisms exist has important implications for antiarrhythmic drug design and for comparisons of fibrillation experiments using different species, electromechanical uncoupling drugs, and initiation protocols.

Fenton, Flavio H.; Cherry, Elizabeth M.; Hastings, Harold M.; Evans, Steven J.

2002-09-01

26

Mechanism of ternary breakup in the reaction Au197+Au197 at 15A MeV  

NASA Astrophysics Data System (ADS)

The mechanism of the ternary breakup of the very heavy system Au197+Au197 at an energy of 15A MeV has been studied by using the improved quantum molecular dynamics model. The calculation results reproduce the characteristic features in ternary breakup events explored in a series of experiments; i.e., the masses of three fragments are comparable in size and the very fast, nearly collinear breakup of the colliding system is dominant in the ternary breakup events. Further, the evolution of the time scales of different ternary reaction modes and the behavior of mass distributions of three fragments with impact parameters are studied. The time evolution of the configurations of the composite reaction systems is also studied. We find that for most of the ternary breakup events with the features found in the experiments, the configuration of the composite system has two-preformed-neck shape. The study shows that those ternary breakup events having the characteristic features found in the experiments happen at relatively small impact parameter reactions, but not at peripheral reactions. The ternary breakup reaction at peripheral reactions belongs to binary breakup with a neck emission.

Tian, Junlong; Wu, Xizhen; Li, Zhuxia; Zhao, Kai; Zhang, Yingxun; Li, Xian; Yan, Shiwei

2010-11-01

27

Fracture Mechanical Analysis of Frost Wedging in Ice Shelves as Break-Up Mechanism  

NASA Astrophysics Data System (ADS)

Disintegration events in ice shelves have been the subject of extensive investigations in the past years, however comprehensive explanations applicable to a majority of events are still missing. A popular assumption made by Scambos et al. (2000) [1] links disintegration events to a general thinning of the ice shelf in conjunction with growing melt-water ponds leading to hydro fractures. This explanation seems reasonable for break-up events that happened in Antarctic summers. Large parts of the Wilkins Ice Shelf, however broke-up in fall and winter periods. Therefore, the aim of the present study is to analyse the possibility of frost wedging of water filled surface crevasses in an ice shelf as a source of break-up events. Configurational forces are used to assess crack criticality. The simulations are performed on a 2-dimensional single crack with a mode-I type load, body forces and additional crack-face pressure due to freezing of the water. Depth-dependent density profiles are considered. The relevant parameters, Young's modulus, Poisson's ratio and external loading are obtained from literature, remote sensing data analysis and modelling of the ice dynamics. The investigation is performed using the finite element software COMSOL. The simulations show that in comparison to water filled crevasses without ice, thin layers of frozen water may lead to a decreasing criticality at the crack tip as long as the ice 'bridge' is allowed to take tensile loads. An increasing crack criticality can be seen for thicker layers of ice. The results are compared to findings from previous finite element analyses of dry and water filled cracks as presented in Plate et al. (2012) [2]. [1] Scambos, T., Hulbe, C., Fahnestock, M., & Bohlander, J. (2000). The link between climate warming and break-up of ice shelves in the Antarctic Peninsula. Journal of Glaciology, 46(154), 516-530. [2] Plate, C., Müller, R., Humbert, A., & Gross, D. (2012). Evaluation of the criticality of cracks in ice shelves using finite element simulations. The Cryosphere, 6(5), 973-984.

Plate, Carolin; Humbert, Angelika; Gross, Dietmar; Müller, Ralf

2013-04-01

28

Mechanism of Coulomb breakup reactions of two-neutron halo nuclei 6He and 11Li  

NASA Astrophysics Data System (ADS)

We investigate the three-body Coulomb breakup reactions of two-neutron halo nuclei and discuss the correlations of every binary subsystem such as of core-n and n-n by showing the invariant mass spectra. It is found that the final-state interactions of core-n and n-n binary subsystems dominantly determine the observed energy distributions of the breakup cross sections, such as the low-lying enhancements. Furthermore, we investigate the effects of the 9Li core excitations on the Coulomb breakup cross section of 11Li. It is shown that the integrated E1 strength at low energy region is reduced by ~ 15 % by the inclusion of the 9Li core excitations.

Kikuchi, Yuma; Myo, Takayuki; Kat?, Kiyoshi; Ikeda, Kiyomi

2014-12-01

29

Description of Jet Breakup  

NASA Technical Reports Server (NTRS)

In this article we review recent results on the breakup of cylindrical jets of a Newtonian fluid. Capillary forces provide the main driving mechanism and our interest is in the description of the flow as the jet pinches to form drops. The approach is to describe such topological singularities by constructing local (in time and space) similarity solutions from the governing equations. This is described for breakup according to the Euler, Stokes or Navier-Stokes equations. It is found that slender jet theories can be applied when viscosity is present, but for inviscid jets the local shape of the jet at breakup is most likely of a non-slender geometry. Systems of one-dimensional models of the governing equations are solved numerically in order to illustrate these differences.

Papageorgiou, Demetrios T.

1996-01-01

30

The Breakup  

ERIC Educational Resources Information Center

This article reports on the breakup between Texas Southmost College (TSC) and the upper-division University of Texas at Brownsville (UTB). The split marks the official end of an unusual 20-year partnership between TSC and the University of Texas System that, for the first time, ushered four-year university education into overwhelmingly Latino…

Lum, Lydia

2011-01-01

31

Stream breakup by waves  

NASA Astrophysics Data System (ADS)

An imaging technique is used to investigate the fluid dynamics associated with the breakup of a liquid jet by a passing transverse shock wave. This mechanism is believed to be a potential source of combustion instability in liquid propellant rocket engines. Combustion instability is caused by the release of heat in phase with a passing pressure disturbance. The jet/wave interaction causes rapid atomization and propellant redistribution, and enhances mixing, vaporization, and reaction rates. Knowledge of the breakup process aids in prediction of local heat release with respect to the passing wave and provides insight on its viability as a potential instability mechanism. The present shock tube study applies high-speed, high-resolution photography to explore the jet/wave interaction that might be experienced in a large scale liquid oxygen/hydrogen (LOX/H2) engine similar to the Space Shuttle Main Engine (SSME) or other such engines being considered for the next generation of launch systems. Fluid parameters deemed important were simulated as well as possible. Two types of wave induced breakup were examined: a constant velocity flow field (square wave) and an exponentially decaying velocity field (N-wave). Time resolved images of the jet/wave interaction indicate very rapid and fire atomization within 500 microns of impingement. Shock interaction with the primary atomization process produces a substantial change to the breakup mechanism and serves as a principal candidate for the promotion and acceleration of rocket engine instability. Results of the qualitative and quantitative study reveal that the step wave produces a long duration tangential and normal stress on the liquid column as compared to the N-wave. As a result, N-waves decelerate jet displacement and extend the jet breakup time.

Samuelsen, G. S.; Ateshkadi, Arash

1995-04-01

32

Breakup of SUSY Quantum Mechanics in the Limit-Circle Region of the Reflective Kratzer Oscillator  

E-print Network

The paper studies violation of conventional rules of SUSY quantum mechanics for the centrifugal potential V(r) within the limit-circle (LC) range. A special attention is given to transformation properties of the Titchmarsh-Weyl m-function under Darboux deformations of the reflective Kratzer oscillator: centrifugal Kepler-Coulomb (KC) potential plus a Taylor series in r. Since our analysis is based on Fulton's representation of a regular-at-infinity solution [Math. Nachr. 281, 1418 (2008)] as a superposition of two Frobenius solutions at the origin, we refer to the appropriate expressions as the Titchmarsh-Weyl-Fulton (TWF) functions. Explicit transformation relations are derived for partner TWF functions associated with SUSY pairs of centrifugal potentials. It is shown that these relations have a completely different form for Darboux transformations (DTs) keeping the potential within the LC range. As an illustration, we use regular nodeless Frobenius solutions to construct SUSY partners of the radial r- and c-Gauss-reference (GRef) potentials solvable via hypergeometric and confluent hypergeometric functions, respectively. We explicitly demonstrate existence of non-isospectral partners of both radial potentials in the LC region and obtain their discrete energy spectra using the derived closed-form expressions for the TWF functions. The general transformation relations for the TWF function have been verified taking advantage of form-invariance of the radial GRef potentials under double-step DTs with the so-called 'basic' seed solutions (SSs). Similarly we directly ratify that TWF functions for three shape-invariant reflective potentials on the half-line -- hyperbolic Poschl-Teller (h-PT), Eckart/Manning-Rosen (E/MR), and centrifugal KC potentials - do retain their form under basic DTs.

Gregory Natanson

2014-05-07

33

Surviving Atmospheric Spacecraft Breakup  

NASA Technical Reports Server (NTRS)

In essence, to survival a spacecraft breakup an animal must not experience a lethal event. Much as with surviving aircraft breakup, dissipation of lethal forces via breakup of the craft around the organism is likely to greatly increase the odds of survival. As spacecraft can travel higher and faster than aircraft, it is often assumed that spacecraft breakup is not a survivable event. Similarly, the belief that aircraft breakup or crashes are not survivable events is still prevalent in the general population. As those of us involved in search and rescue know, it is possible to survive both aircraft breakup and crashes. Here we make the first report of an animal, C. elegans, surviving atmospheric breakup of the spacecraft supporting it and discuss both the lethal events these animals had to escape and the implications implied for search and rescue following spacecraft breakup.

Szewczyk, Nathaniel J.; Conley, Catharine A.

2003-01-01

34

Satellite Breakup Risk Mitigation  

NASA Technical Reports Server (NTRS)

Many satellite breakups occur as a result of an explosion of stored energy on-board spacecraft or rocket-bodies. These breakups generate a cloud of tens or possibly hundreds of thousands of debris fragments which may pose a transient elevated threat to spaceflight crews and vehicles. Satellite breakups pose a unique threat because the majority of the debris fragments are too small to be tracked from the ground. The United States Human Spaceflight Program is currently implementing a risk mitigation strategy that includes modeling breakup events, establishing action thresholds, and prescribing corresponding mitigation actions in response to satellite breakups.

Leleux, Darrin P.; Smith, Jason T.

2006-01-01

35

Experimental Investigation of the Few-Nucleon Dynamics in Deuteron-Deuteron Collision at 160 MeV  

NASA Astrophysics Data System (ADS)

An experiment, with unpolarized deuteron beam of 160 MeV impinging on liquid deuterium target, was carried out using BINA detector at KVI, in Groningen, the Netherlands. Data were collected for the purpose of obtaining high precision differential cross-section for the deuteron break-up reaction. The elastic scattering data were also collected alongside for the purpose of cross-section normalization. We present here a sample of the un-normalised cross-section for the three-body final state (dd?dpn) reaction.

Khatri, G.; Bodek, K.; Ciepa?, I.; Kalantar-Nayestanaki, N.; Kistryn, St.; K?os, B.; Kozela, A.; Magiera, A.; Mazumdar, I.; Messchendorp, J.; Parol, W.; Rozp?dzik, D.; Skwira-Chalot, I.; Stephan, E.; Wro?ska, A.; Zejma, J.

2014-11-01

36

Effect of the phase space factor in the breakup of composite particles  

NASA Astrophysics Data System (ADS)

The need to include the phase space factor in the analysis of ? breakup spectra according to Fermi's Golden Rule is indicated. The importance of the number of particles present in the final state is exemplified by a model calculation for proton, deuteron, and triton spectra produced by the breakup of 160 MeV alphas on zirconium. NUCLEAR REACTIONS phase space factor, model alpha breakup spectra for Zr(?,xp), Zr(?,xd), and Zr(?,xt) reactions at E?=160 MeV.

Pai?, G.; Antolkovi?, B.

1981-04-01

37

Electrodisintegration of $^3$He below and above deuteron breakup threshold  

E-print Network

Recent advances in the study of electrodisintegration of 3He are presented and discussed. The pair-correlated hyperspherical harmonics method is used to calculate the initial and final state wave functions, with a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana IX three-nucleon interactions. The model for the nuclear current and charge operators retains one- and many-body contributions. Particular attention is made in the construction of the two-body current operators arising from the momentum-dependent part of the two-nucleon interaction. Three-body current operators are also included so that the full current operator is strictly conserved. The present model for the nuclear current operator is tested comparing theoretical predictions and experimental data of pd radiative capture cross section and spin observables.

L. E. Marcucci; M. Viviani; R. Schiavilla; A. Kievsky; S. Rosati

2004-11-19

38

Relating breakup and incomplete fusion of weakly bound nuclei through a classical trajectory model with stochastic breakup.  

PubMed

A classical dynamical model that treats breakup stochastically is presented for low energy reactions of weakly bound nuclei. The three-dimensional model allows a consistent calculation of breakup, incomplete, and complete fusion cross sections. The model is assessed by comparing the breakup observables with continuum discretized coupled-channel quantum mechanical predictions, which are found to be in reasonable agreement. Through the model, it is demonstrated that the breakup probability of the projectile as a function of its distance from the target is of primary importance for understanding complete and incomplete fusion at energies near the Coulomb barrier. PMID:17501341

Diaz-Torres, A; Hinde, D J; Tostevin, J A; Dasgupta, M; Gasques, L R

2007-04-13

39

180 Degree Electron Scattering from the Deuteron  

NASA Astrophysics Data System (ADS)

Transverse electron scattering from the deuteron has been measured at the MIT-Bates Linear Accelerator for eleven incident energies in the range from 133 to 373 MeV, and deuteron excitation energies as large as 222 MeV. These data were acquired at a scattering angle of 180 where the cross sections are directly related to the transverse form factors without the need of Rosenbluth separations. Nuclear interaction effects, such as meson exchange currents and isobar configurations, are predicted to make significant contributions to the magnetic current structure of the deuteron that is sampled in the measurement of the transverse form factor. In this experiment a systematic study was made of predictions for various features of the excitation energy spectrum including the elastic peak, the threshold breakup cusp, the quasielastic peak, the dip region, and the beginning of the deep-inelastic region beyond pion production threshold. Gaseous deuterium and hydrogen targets were utilized for these measurements. The proton elastic cross section was used to set the target thickness normalization. The data were corrected for background due to direct scattering from the beam entrance and exit windows of the gas-target cells. The exact single hard-photon formalism of Mo and Tsai, with a multiplicative correction factor for multiple soft-photon emission, was used in making radiative corrections for the emission of real photons before or after scattering. The experimental data are found to be in qualitative agreement with theory, and support the existence of meson exchange current and isobar configuration effects. For instance the predicted threshold breakup cross section would be significantly lower than the data without the inclusion of meson exchange currents. There are quantitative differences between theory and experiment which indicate the need for further improvement in the theoretical calculations.

Parker, Brett Lee

40

Crossover between Rayleigh-Taylor Instability and turbulent cascading atomization mechanism in the bag-breakup regime  

E-print Network

The question whether liquid atomization (or pulverization) resorts to instability dynamics (through refinements of Rayleigh-Plateau, Rayleigh-Taylor or Kelvin-Helmholtz mechanism) or to turbulent cascades similar to Richardson and Kolmogorov first ideas seems to be still open. In this paper, we report experimental evidences that both mechanisms are needed to explain the spray drop PDF obtained from an industrial nozzle. Instability of Rayleigh-Taylor kind governs the size of the largest droplets while the smallest ones obey a PDF given by a turbulent cascading mechanism resulting in a log-L\\'evy stable law of stability parameter close to 1.68. This value, very close to the inverse of the Flory exponent, can be related to a recent model for intermittency modeling stemming from self-avoiding random vortex stretching.

Nicolas Rimbert; Guillaume Castanet

2010-05-31

41

Theory of Bose-Einstein condensation mechanism for deuteron-induced nuclear reactions in micro/nano-scale metal grains and particles.  

PubMed

Recently, there have been many reports of experimental results which indicate occurrences of anomalous deuteron-induced nuclear reactions in metals at low energies. A consistent conventional theoretical description is presented for anomalous low-energy deuteron-induced nuclear reactions in metal. The theory is based on the Bose-Einstein condensate (BEC) state occupied by deuterons trapped in a micro/nano-scale metal grain or particle. The theory is capable of explaining most of the experimentally observed results and also provides theoretical predictions, which can be tested experimentally. Scalabilities of the observed effects are discussed based on theoretical predictions. PMID:19440686

Kim, Yeong E

2009-07-01

42

Tensor analyzing powers for {sup 7}Li breakup  

SciTech Connect

Differential cross sections and {ital T}{sub 20} and {sup {ital T}}{ital T}{sub 20} analyzing powers have been measured for 70 MeV {sup 7}Li breakup into the {alpha} particle plus triton channel, on a {sup 120}Sn target. Measurements were made for both continuum breakup and sequential breakup via the 4.63 MeV state in {sup 7}Li. The {ital T}{sub 20} data for the continuum breakup do not agree with a semiclassical Coulomb model, indicating that the breakup at small angles does not proceed solely via a Coulomb force. The data generally show a somewhat better agreement with continuum discretized coupled channels calculations, indicating the importance of the nuclear force and channel coupling in the reaction mechanism.

Davis, N.J.; Shepherd-Themistocleous, C.H.; Shotter, A.C.; Davinson, T.; Ireland, D.G.; Livingston, K.; Macdonald, E.W.; Page, R.D.; Sellin, P.J.; Woods, P.J. [Department of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (United Kingdom)] [Department of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (United Kingdom); Clarke, N.M.; Tungate, G.; Griffith, J.A.R.; Hall, S.J.; Karban, O.; Martel-Bravo, I.; Nelson, J.M. [School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)] [School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Rusek, K. [Soltan Institute for Nuclear Studies, Zaklad 1, Hoza 69, 00 681 Warsaw (Poland)] [Soltan Institute for Nuclear Studies, Zaklad 1, Hoza 69, 00 681 Warsaw (Poland); Gomez-Camacho, J. [Departmento de FAMN, Facultad de Fisicas, Universidad de Sevilla, Aptdo. 1065, 41080 Sevilla (Spain)] [Departmento de FAMN, Facultad de Fisicas, Universidad de Sevilla, Aptdo. 1065, 41080 Sevilla (Spain)

1995-12-01

43

Excitation of the ?(1232) isobar in deuteron charge exchange on hydrogen at 1.6, 1.8, and 2.3 GeV  

NASA Astrophysics Data System (ADS)

The charge-exchange break-up of polarised deuterons d?p?{pp}sn, where the final {pp}s diproton system has a very low excitation energy and hence is mainly in the S01 state, is a powerful tool to probe the spin-flip terms in the proton-neutron charge-exchange scattering. Recent measurements with the ANKE spectrometer at the COSY storage ring at 1.6, 1.8, and 2.27 GeV have extended these studies into the pion-production regime in order to investigate the mechanism for the excitation of the ?(1232) isobar in the d?p?{pp}sX reaction. Values of the differential cross section and two deuteron tensor analysing powers, Axx and Ayy, have been extracted as functions of the momentum transfer to the diproton or the invariant mass MX of the unobserved system X. The unpolarised cross section in the high MX region is well described in a model that includes only direct excitation of the ? isobar through undistorted one pion exchange. However, the cross section is grossly underestimated for low MX, even when ? excitation in the projectile deuteron is included in the calculation. Furthermore, direct ? production through one pion exchange only reproduces the angular dependence of the difference between the two tensor analysing powers.

Mchedlishvili, D.; Barsov, S.; Carbonell, J.; Chiladze, D.; Dymov, S.; Dzyuba, A.; Engels, R.; Gebel, R.; Glagolev, V.; Grigoryev, K.; Goslawski, P.; Hartmann, M.; Imambekov, O.; Kacharava, A.; Kamerdzhiev, V.; Keshelashvili, I.; Khoukaz, A.; Komarov, V.; Kulessa, P.; Kulikov, A.; Lehrach, A.; Lomidze, N.; Lorentz, B.; Macharashvili, G.; Maier, R.; Merzliakov, S.; Mielke, M.; Mikirtychyants, M.; Mikirtychyants, S.; Nioradze, M.; Ohm, H.; Papenbrock, M.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Seyfarth, H.; Stein, H. J.; Steffens, E.; Stockhorst, H.; Ströher, H.; Tabidze, M.; Trusov, S.; Uzikov, Yu.; Valdau, Yu.; Wilkin, C.

2013-10-01

44

Configuration-space Faddeev calculation for proton-deuteron observables at energy E{sub lab} = 3 MeV  

SciTech Connect

A new computational method for solving the nucleon-deuteron breakup scattering problem has been applied to study the elastic neutron- and proton-deuteron scattering on the basis of the configuration-space Faddeev-Noyes-Noble-Merkuriev equations. This method is based on the spline-decomposition in the angular variable and on a generalization of the Numerov method for the hyperradius. The Merkuriev-Gignoux-Laverne approach has been generalized for arbitrary nucleon-nucleon potentials and with an arbitrary number of partial waves taken into account. The nucleon-deuteron observables at the incident nucleon energy 3 MeV have been calculated using the charge-independent AV14 nucleon-nucleon potential including the Coulomb force for the proton-deuteron scattering. Results have been compared with those of other authors and with experimental proton-deuteron scattering data.

Suslov, V. M.; Filikhin, I.; Vlahovic, B.; Slaus, I. [Department of Physics, North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707,USA (United States); Braun, M. A. [Department of Physics, North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707,USA (United States); Department of High Energy Physics and Elementary Particles,Saint-Petersburg State University, 198504, Petrodvorets, St. Petersburg (Russian Federation)

2011-10-24

45

Study of all Reaction Channels in Deuteron-Deuteron Scattering  

NASA Astrophysics Data System (ADS)

Few-nucleon systems can be used as fundamental laboratories for studying details of the nuclear force effects. We performed a series of deuteron-deuteron scattering experiments at intermediate energies. The experiments exploited BINA and BBS experimental setups and polarized deuteron beams with kinetic energies of 65 and 90 MeV/nucleon. These experiments aim to measure differential cross sections, vector and tensor analyzing powers of all available reaction channels in deuteron-deuteron scattering. With these data we will provide a systematic database, which will be used to test present theoretical approximations and upcoming ab-initio calculations in four-nucleon system.

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

46

Compact LINAC for deuterons  

SciTech Connect

We are developing a compact deuteron-beam accelerator up to the deuteron energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IHPMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.

Kurennoy, S S [Los Alamos National Laboratory; O' Hara, J F [Los Alamos National Laboratory; Rybarcyk, L J [Los Alamos National Laboratory

2008-01-01

47

Two facets of the deuteron  

SciTech Connect

Two of the simplest nuclear reactions, electron deuteron elastic scattering and deuteron photodisintegration, will be discussed. In particular, measurements of the tensor analyzing power T{sub 20} in e-d scattering performed with a polarized gas target in the VEPP-3 electron storage ring will be presented. In addition, measurements of deuteron photodisintegration at high energy performed at SLAC will be discussed. The meson-exchange calculations appear to agree well with al available data for electron-deuteron elastic scattering, while the constituent counting rules appear to describe the high-energy deuteron photodisintegration results at {theta}cm = 90{degrees}.

Holt, R.J.

1992-01-01

48

Two facets of the deuteron  

SciTech Connect

Two of the simplest nuclear reactions, electron deuteron elastic scattering and deuteron photodisintegration, will be discussed. In particular, measurements of the tensor analyzing power T{sub 20} in e-d scattering performed with a polarized gas target in the VEPP-3 electron storage ring will be presented. In addition, measurements of deuteron photodisintegration at high energy performed at SLAC will be discussed. The meson-exchange calculations appear to agree well with al available data for electron-deuteron elastic scattering, while the constituent counting rules appear to describe the high-energy deuteron photodisintegration results at {theta}cm = 90{degrees}.

Holt, R.J.

1992-09-01

49

Large-Scale Climate Controls of Interior Alaska River Ice Breakup PETER A. BIENIEK AND UMA S. BHATT  

E-print Network

. The breakup of river ice can also lead to ice jams and flooding in spring (Beltaos 2008) and occurs whenLarge-Scale Climate Controls of Interior Alaska River Ice Breakup PETER A. BIENIEK AND UMA S. BHATT, it is important to understand the key mechanisms that control the timing of river ice breakup. The relationships

Bhatt, Uma

50

Magmatism and deformation during continental breakup  

NASA Astrophysics Data System (ADS)

The rifting of continents and the transition to seafloor spreading is characterised by extensional faulting and thinning of the lithosphere, and is sometimes accompanied by voluminous intrusive and extrusive magmatism. In order to understand how these processes develop over time to break continents apart, we have traditionally relied on interpreting the geological record at the numerous fully developed, ancient rifted margins around the world. In these settings, however, it is difficult to discriminate between different mechanisms of extension and magmatism because the continent-ocean transition is typically buried beneath thick layers of volcanic and sedimentary rocks, and the tectonic and volcanic activity that characterised breakup has long-since ceased. Ongoing continental breakup in the African and Arabian rift systems offers a unique opportunity to address these problems because it exposes several sectors of tectonically active rift sector development spanning the transition from embryonic continental rifting in the south to incipient seafloor spreading in the north. Here I synthesise exciting, multidisciplinary observational and modelling studies using geophysical, geodetic, petrological and numerical techniques that uniquely constrain the distribution, time-scales, and interactions between extension and magmatism during the progressive breakup of the African Plate. This new research has identified the previously unrecognised role of rapid and episodic dike emplacement in accommodating a large proportion of extension during continental rifting. We are now beginning to realise that changes in the dominant mechanism for strain over time (faulting, stretching and magma intrusion) impact dramatically on magmatism and rift morphology. The challenge now is to take what we're learned from East Africa and apply it to the rifted margins whose geological record documents breakup during entire Wilson Cycles.

Keir, Derek

2013-04-01

51

Dynamical effects in proton breakup from exotic nuclei  

SciTech Connect

This contribution discusses dynamical effects in proton breakup from a weakly bound state in an exotic nucleus on a heavy target. The Coulomb interactions between the proton and the core and the proton and the target are treated to all orders, including also the full multipole expansion of the Coulomb potential. The dynamics of proton Coulomb breakup is compared to that of an equivalent neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism. A number of experimentally measurable observables such as parallel momentum distributions, proton angular distributions and total breakup cross sections can be calculated. With respect to nuclear breakup it is found that a proton behaves exactly as a neutron of larger binding energy. The extra 'effective energy' is due to the combined core-target Coulomb barrier. In Coulomb breakup we distinguish the effect of the core-target Coulomb potential (called recoil effect), with respect to which the proton behaves again as a more bound neutron, from the direct proton-target Coulomb potential. The latter gives cross sections about an order of magnitude larger than the recoil term. The two effects give rise to complicated interferences in the parallel momentum distributions. They are instead easily separable in the proton angular distributions which are therefore suggested as a very useful observable for future experimental studies.

Bonaccorso, Angela; Kumar, Ravinder [INFN, Sez. di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); INFN, Sez. di Pisa, Largo B. Pontecorvo 3, 56127 Pisa and Department of Physics, Deenbandhu Chhoturam University of Science and Technology, Murthal, Sonepat, Haryana, 131039 (India)

2012-10-20

52

Breakup of drops in a microfluidic T junction  

NASA Astrophysics Data System (ADS)

We propose a mechanism of droplet breakup in a symmetric microfluidic T junction driven by pressure decrement in a narrow gap between the droplet and the channel wall. This mechanism works in a two-dimensional setting where the capillary (Rayleigh-Plateau) instability of a cylindrical liquid thread, suggested earlier [D. Link, S. Anna, D. Weitz, and H. Stone, Phys. Rev. Lett. 92, 054503 (2004)] as the cause of breakup, is not operative, but it is likely to be responsible for the breakup also in three dimensions. We derive a dependence of the critical droplet extension on the capillary number Ca by combining a simple geometric construction for the interface shape with lubrication analysis in a narrow gap where the surface tension competes with the viscous drag. The theory, formally valid for Ca1/5?1, shows a very good agreement with numerical results when it is extrapolated to moderate values of Ca.

Leshansky, A. M.; Pismen, L. M.

2009-02-01

53

Basis for Breakup States of Three Identical Particles  

NASA Astrophysics Data System (ADS)

A new basis for expanding three-body momentum-space states for three identical particles is studied. The basis states are simultaneously eigenstates of the total angular momentum and the total antisymmetrization operator. The total kinetic energy and two Dalitz-Fabri variables are chosen as the remaining three continuous variables. Zernike polynomials are used as a basis set for a generalized Fourier expansion in the Dalitz-Fabri variables. Born approximations to the nucleon-deuteron breakup amplitude (zero total orbital angular momentum) are calculated for Malfliet-Tjon I-III potentials and displayed in a Dalitz plot that shows the global structures of the reaction probabilities. Numerical results are presented, which indicate favorable convergence properties of the generalized Fourier expansion. These results suggest that the new basis set may be attractive in more realistic calculations.

Chandler, C.; Gibson, A. G.

54

Effect of AN Off-Shell Transformation of the Quark-Model NN Interaction in the Neutron-Deuteron Scattering  

NASA Astrophysics Data System (ADS)

The neutron-deuteron (nd) scattering is studied in the Faddeev formalism, employing the NN sector of the quark-model baryon-baryon interaction fss2. The energy-dependence of the NN interaction, inherent to the resonating-group formulation of two three-quark clusters, is eliminated by the standard off-shell transformation utilizing the square root of the normalization kernel. This procedure yields an extra nonlocality to the quark-model exchange kernel, which is very important to reproduce all the observables for the bound state and the elastic scattering below En ? 65 MeV. The deuteron breakup differential cross sections are also examined.

Fujiwara, Y.; Fukukawa, K.

55

Drop breakup and deformation in sudden onset strong flows  

NASA Astrophysics Data System (ADS)

This work characterizes the deformation and breakup of a single drop subjected to a sudden onset shear flow. The drop is immersed in a second fluid (the matrix) with which it is immiscible. A cylindrical couette device is used to create a flow field which, in the absence of the drop, would constitute a close approximation of simple shear flow. The magnitude of the imposed shear rate was greater than that which would be necessary to just break the drop. The experiments conducted were limited to matrix fluid viscosities above 7Pa? s and shear rates below 15/s, ensuring that the flows considered were inertialess. The matrix fluid was a corn syrup solution. The drop fluids were polybutadiene, paraffin oil and silicone oil, leading to a range of interfacial tensions. At the shear rates used in these experiments the fluids used Newtonian. Viscosity ratios (drop/matrix) ranging from 0.01 to 1 were considered. Two breakup mechanisms were observed to contribute to the dispersion of the original drop. In all cases elongative end pinching, defined by this study, caused the ends of a stretching drop to break off and form daughter drops. Breakup due to elongative end pinching was always the first breakup observed. The daughter drops formed by elongative end pinching were always the largest daughter drops formed. In cases when the experimental conditions were sufficiently stronger than the critical conditions (needed to just barely break up the drop), a second type of breakup, capillary wave breakup, was also observed. Measurement of the characteristic time scales and length scales were made of each type of breakup. The lengths (a) were found to scale as capillary numbers: Ca=a mg/s. The times (t) were found to scale as strains: s=t g. A qualitative explanation for the capillary number scaling is presented and quantitatively compared to predictions based on small deformation analysis. Additionally the daughter drop size distributions resulting from drop breakup is characterized. These distributions are shown to be dependent on the relative dominance of the two breakup mechanisms observed.

Marks, Charles Raphael

56

Spiral vortices and liquid breakup  

Microsoft Academic Search

Axially directed spiral vortices have been observed in an internal cavity flow, with attention to the breakup behavior of a liquid droplet placed in the initiation point of a vortex. A dynamic process is identified, on the basis of the axially detected spiral vortices from wall shear layers and separated from shear layers studied, which could furnish a key for

L. K. Isaacson

1986-01-01

57

A fundamental study of liquid phase particle breakup. Revision  

NASA Astrophysics Data System (ADS)

Combustion efficiency of aluminized propellants in solid rocket motors is reduced by incomplete aluminum combustion and two-phase nozzle flow losses. Combustion of these propellants can produce large Al/Al2O3 agglomerates. As a direct result of agglomerate breakup, the aluminum combustion rate is increased, and the thermal energy released is more efficiently transferred into exhaust kinetic energy. This research sought to obtain physical data to characterize the mechanisms of aerodynamic droplet breakup. Experiments have been completed in which conventional liquids and a liquid metal (mercury) was studied. The primary goal of the conventional liquid experiments was to examine the effect of liquid properties (viscosity and surface tension) on the breakup mechanism, time scale, and fragment size distribution. The goal of the mercury experiments was to examine the effect of the much higher surface tension more characteristic of liquid aluminum. A key element of the experimental effort is the use of nonintrusive laser diagnostics including pulsed laser holography (PLH) and laser Doppler velocimetry (LDV). The exceptional temporal and spatial resolution of PLH provided the ability to resolve the mechanism of breakup and the size distribution of the fragments. LDV was used to determine drop velocity distributions along the nozzle revealing the rapid acceleration of the flattened droplets and then, surprisingly, the milder acceleration of the fragments.

1984-12-01

58

Isomer ratio measurements as a probe of the dynamics of breakup and incomplete fusion  

SciTech Connect

The incomplete fusion mechanism following breakup of {sup 6,7}Li and {sup 9}Be projectiles incident on targets of {sup 209}Bi and {sup 208}Pb is investigated through isomer ratio measurements for the {sup 212}At and {sup 211}Po products. The phenomenological analysis presented in this paper indicates that incomplete fusion brings relatively more angular momentum into the system than equivalent reactions with a direct beam of the fused fragment. This is attributed to the trajectories of breakup fragments. Calculations with a 3D classical trajectory model support this. Isomer ratio measurements for incomplete fusion reactions can provide a test of new theoretical models of breakup and fusion.

Gasques, L. R.; Dasgupta, M.; Hinde, D. J.; Peatey, T.; Diaz-Torres, A.; Newton, J. O. [Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

2006-12-15

59

Electrohydrodynamic (EHD) stimulation of jet breakup  

NASA Technical Reports Server (NTRS)

Electrohydrodynamic (EHD) excitation of liquid jets offers an alternative to piezoelectric excitation without the complex frequency response caused by piezoelectric and mechanical resonances. In an EHD exciter, an electrode near the nozzle applies an alternating Coulomb force to the jet surface, generating a disturbance which grows until a drop breaks off downstream. This interaction is modelled quite well by a linear, long wave model of the jet together with a cylindrical electric field. The breakup length, measured on a 33 micrometer jet, agrees quite well with that predicted by the theory, and increases with the square of the applied voltage, as expected. In addition, the frequency response is very smooth, with pronounced nulls occurring only at frequencies related to the time which the jet spends inside the exciter.

Crowley, J. M.

1982-01-01

60

Phenomenology of the Deuteron Electromagnetic Form Factors  

E-print Network

A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm^-1. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.

TheJLAB t20 collaboration; D. Abbott

2000-02-04

61

The naming of the deuteron  

Microsoft Academic Search

The naming of the deuteron involved a protracted debate between 1933 and 1935. The principal protagonists were Harold C. Urey, Gilbert N. Lewis, Ernest O. Lawrence, and Ernest Rutherford, but others on both sides of the Atlantic entered the fray as well. This paper examines the arguments and issues that emerged in the debate, and the process by which agreement

Roger H. Stuewer

1986-01-01

62

Jet breakup and droplet formation in near-critical regime of carbon dioxide–dichloromethane system  

Microsoft Academic Search

The jet breakup and droplet formation mechanism of a liquid in the near-critical conditions of a solvent–antisolvent system is examined with high-speed visualization experiments and simulated using a front tracking\\/finite volume method. The size of droplets formed under varying system pressure at various jet breakup regimes is measured with a Global Sizing Velocimetry, using the shadow sizing method. A stainless

Lai Yeng Lee; Liang Kuang Lim; Jinsong Hua; Chi-Hwa Wang

2008-01-01

63

Beam breakup in a microtron  

SciTech Connect

In a microtron, the path length change from pass to pass is a fixed multiple of the RF wavelength, and the accelerating system can be reasonably well approximated as a single cavity. Under such circumstances it is possible to derive an analytical formula for the multipass beam breakup threshold current. The threshold current determined by numerical simulations agrees very well with the formula for a machine with a small number of passes. The analytic formula can serve as a useful guide in examining optics designs to improve the BBU threshold.

Yung, B.C.; Merminga, L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

1997-06-01

64

High Energy Break-Up of Few-Nucleon Systems  

E-print Network

We discus recent developments in theory of high energy two-body break-up reactions of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon by the outgoing two nucleons. Within HRM we discuss hard break-up reactions involving $^2D$ and $^3He$ targets. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.

Misak M. Sargsian

2008-01-14

65

Comparisons of debris environment model breakup models  

Microsoft Academic Search

This paper presents a comparison of current spacecraft breakup models used in orbital (space) debris computational environment models. The breakup models to be compared come from the NASA EVOLVE (Evolutionary) model long term debris model, the IMPACT code developed by Aerospace Corp., and the Fragmentation Algorithms for Satellite Targets (FAST) developed by Kaman Sciences. The comparison will show the methodologies

F. Jonas; K. Yates; R. Evans

1993-01-01

66

Antimisting fuel breakup and flammability  

NASA Technical Reports Server (NTRS)

The breakup behavior and flammability of antimisting turbine fuels subjected to aerodynamic shear are investigated. Fuels tested were Jet A containing 0.3% FM-9 polymer at various levels of degradation ranging from virgin AMK to neat Jet A. The misting behavior of the fuels was quantified by droplet size distribution measurements. A technique based on high resolution laser photography and digital image processing of photographic records for rapid determination of droplet size distribution was developed. The flammability of flowing droplet-air mixtures was quantified by direct measurements of temperature rise in a flame established in the wake of a continuous ignition source. The temperature rise measurements were correlated with droplet size measurements. The flame anchoring phenomenon associated with the breakup of a liquid fuel in the wake of bluff body was shown to be important in the context of a survivable crash scenario. A pass/fail criterion for flammability testing of antimisting fuels, based on this flame-anchoring phenomenon, was proposed. The role of various ignition sources and their intensity in ignition and post-ignition behavior of antimisting fuels was also investigated.

Parikh, P.; Fleeter, R.; Sarohia, V.

1983-01-01

67

Breakup of diminutive Rayleigh jets  

NASA Astrophysics Data System (ADS)

Discharging a liquid from a nozzle at sufficient large velocity leads to a continuous jet that due to capillary forces breaks up into droplets. Here we investigate the formation of microdroplets from the breakup of micron-sized jets with ultra high-speed imaging. The diminutive size of the jet implies a fast breakup time scale ?c=??r3/? of the order of 100 ns, and requires imaging at 14×106 frames/s. We directly compare these experiments with a numerical lubrication approximation model that incorporates inertia, surface tension, and viscosity [J. Eggers and T. F. Dupont, J. Fluid Mech. 262, 205 (1994); X. D. Shi, M. P. Brenner, and S. R. Nagel, Science 265, 219 (1994)]. The lubrication model allows to efficiently explore the parameter space to investigate the effect of jet velocity and liquid viscosity on the formation of satellite droplets. In the phase diagram, we identify regions where the formation of satellite droplets is suppressed. We compare the shape of the droplet at pinch-off between the lubrication approximation model and a boundary-integral calculation, showing deviations at the final moment of the pinch-off. In spite of this discrepancy, the results on pinch-off times and droplet and satellite droplet velocity obtained from the lubrication approximation agree with the high-speed imaging results.

van Hoeve, Wim; Gekle, Stephan; Snoeijer, Jacco H.; Versluis, Michel; Brenner, Michael P.; Lohse, Detlef

2010-12-01

68

Observations of auroral fading before breakup  

NASA Technical Reports Server (NTRS)

The onset of auroral breakup was studied by using a variety of instruments with time resolution of some tens of second. Rapid sequences of all-sky photographs, and fast meridian scans by photometers, show that breakup is usually preceded by moderate brightening, followed by fading of the auroral brightness lasting one or two minutes, before the actual breakup itself. This optical activity is closely correlated with the development of auroral radar echoes. Data from a magnetometer network provide some indication of a correlated response by the local auroral and ionospheric currents. Riometer recordings show a slow decrease in ionspheric radio wave absorption over a period of about ten minutes prior to breakup, with the largest decrease essentially to quiet-time values in the region of auroral fading and subsequent breakup.

Pellinen, R. J.; Heikkila, W. J.

1978-01-01

69

The naming of the deuteron  

NASA Astrophysics Data System (ADS)

The naming of the deuteron involved a protracted debate between 1933 and 1935. The principal protagonists were Harold C. Urey, Gilbert N. Lewis, Ernest O. Lawrence, and Ernest Rutherford, but others on both sides of the Atlantic entered the fray as well. This paper examines the arguments and issues that emerged in the debate, and the process by which agreement was finally achieved on the name for this new particle.

Stuewer, Roger H.

1986-03-01

70

Quenching of the Deuteron in Flight  

E-print Network

We investigate the Lorentz contraction of a deuteron in flight. Our starting point is the Blankenbecler-Sugar projection of the Bethe-Salpeter equation to a 3-dimensional quasi potential equation, wqhich we apply for the deuteron bound in an harmonic oscillator potential (for an analytical result) and by the Bonn NN potential for a more realistic estimate. We find substantial quenching with increasing external momenta and a significant modification of the high momentum spectrum of the deuteron.

M. Dillig; C. Rothleitner

2006-04-24

71

Quenching of the Deuteron in Flight  

NASA Astrophysics Data System (ADS)

We investigate the Lorentz contraction of a deuteron in flight. Starting from the Blankenbecler-Sugar projection of the Bethe-Salpeter equation to a 3-dimensional quasi potential equation, we apply it for the deuteron bound in an harmonic oscillator potential (for an analytical result) or by the Bonn NN potential for a more realistic estimate. We find substantial quenching with increasing external momenta and a significant modification of the high momentum spectrum of the deuteron.

Dillig, M.; Rothleitner, C.

72

Elastic breakup cross sections of well-bound nucleons  

NASA Astrophysics Data System (ADS)

The 9Be(28Mg,27Na ) one-proton removal reaction with a large proton separation energy of Sp(28Mg ) =16.79 MeV is studied at intermediate beam energy. Coincidences of the bound 27Na residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleon removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the removal of more weakly bound protons from lighter nuclei. The role of transitions of the proton between different bound single-particle configurations upon the elastic breakup cross section is also quantified in this well-bound case. The measured and calculated elastic breakup fractions are found to be in good agreement.

Wimmer, K.; Bazin, D.; Gade, A.; Tostevin, J. A.; Baugher, T.; Chajecki, Z.; Coupland, D.; Famiano, M. A.; Ghosh, T. K.; Grinyer, G. F.; Howard, M. E.; Kilburn, M.; Lynch, W. G.; Manning, B.; Meierbachtol, K.; Quarterman, P.; Ratkiewicz, A.; Sanetullaev, A.; Showalter, R. H.; Stroberg, S. R.; Tsang, M. B.; Weisshaar, D.; Winkelbauer, J.; Winkler, R.; Youngs, M.

2014-12-01

73

Elastic breakup cross sections of well-bound nucleons  

E-print Network

The 9Be(28Mg,27Na) one-proton removal reaction with a large proton separation energy of Sp(28Mg)=16.79 MeV is studied at intermediate beam energy. Coincidences of the bound 27Na residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleon removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the re- moval of more weakly-bound protons from lighter nuclei. The role of transitions of the proton between different bound single-particle configurations upon the elastic breakup cross section is also quantified in this well-bound case. The measured and calculated elastic breakup fractions are found to be in good agreement.

K. Wimmer; D. Bazin; A. Gade; J. A. Tostevin; T. Baugher; Z. Chajecki; D. Coupland; M. A. Famiano; T. K. Ghosh; G. F. Grinyer M. E. Howard; M. Kilburn; W. G. Lynch; B. Manning; K. Meierbachtol; P. Quarterman; A. Ratkiewicz; A. Sanetullaev; R. H. Showalter; S. R. Stroberg; M. B. Tsang; D. Weisshaar; J. Winkelbauer; R. Winkler; M. Youngs

2014-12-07

74

Negative Emotions and Behaviors are Markers of Breakup Distress  

ERIC Educational Resources Information Center

Method: University students who experienced a recent romantic breakup were given several self-report measures and were then divided into high versus low breakup distress groups. Results: The high breakup distress versus the low breakup distress groups had higher scores on negative emotions scales including depression, anxiety and anger and…

Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeanette

2013-01-01

75

Triton Breakup and Formation at Very Low Energies  

NASA Astrophysics Data System (ADS)

Different theoretical models for two- and three-body electromagnetic currents are constructed using meson-exchange mechanisms and minimal substitution in the momentum dependence of two- and three-nucleon interactions. We review the use of effective field theory (EFT) to compute electromagnetic reactions in three-nucleon systems at very low energies. We first explain how EFT theory can be extended to incorporate the photon into the three-nucleon systems when also a three-nucleon force is acting. We also explain the predictions of the resulting EFT for neutron-deuteron radiative capture process at very low energies. In this work, a number of low-energy photonuclear observables, including neutron-deuteron radiative capture reactions and triton photodisintegration, are calculated in order to make a comparative study of the pion-less EFT results with the models based on the realistic Argonne v18(AV18) two-nucleon and Urbana IX or Tucson-Melbourne three-nucleon interactions. The calculated cross-section of neutron-deuteron radiative capture and photon polarization parameter of 3H are in satisfactory agreement with the available experimental data.

Sadeghi, H.

2012-09-01

76

Deuteron and Anti-deuteron Production in $e^{+}e^{-}$ Collisions at the Z resonance  

Microsoft Academic Search

Deuteron and anti-deuteron production in Z decays has been observed in the ALEPH experiment at LEP. The production rate of anti-deuterons is measured to be (5.9+-1.8+-0.5) 10^-6 per hadronic Z decay in the anti-deuteron momentum range from 0.62 to 1.03 GeV\\/c. The coalescence parameter B_2, which characterizes the likelihood of anti-deuteron production, is measured to be 0.0033+-0.0013 GeV^2 in Z

S Schael; R Barate; R Brunelière; I De Bonis; D Décamp; C Goy; S Jézéquel; J P Lees; F Martin; E Merle; M N Minard; B Pietrzyk; B Trocmé; S Bravo; M P Casado; M Chmeissani; J M Crespo; E Fernández; M Fernández-Bosman; L Garrido; M Martínez; A Pacheco; H Ruiz; A Colaleo; D Creanza; N De Filippis; M De Palma; G Iaselli; G Maggi; M Maggi; S Nuzzo; A Ranieri; G Raso; F Ruggieri; G Selvaggi; L Silvestris; P Tempesta; A Tricomi; G Zito; X Huang; J Lin; Q Ouyang; T Wang; Y Xie; R Xu; S Xue; J Zhang; L Zhang; W Zhao; D Abbaneo; T Barklow; O L Buchmüller; M Cattaneo; B Clerbaux; H Drevermann; R W Forty; M Frank; F Gianotti; J B Hansen; J Harvey; D E Hutchcroft; P Janot; B Jost; M Kado; P Mato; A Moutoussi; F Ranjard; Luigi Rolandi; W D Schlatter; F Teubert; A Valassi; I Videau; F Badaud; S Dessagne; A Falvard; D Fayolle; P Gay; J Jousset; B Michel; S Monteil; D Pallin; J M Pascolo; P Perret; J D Hansen; P H Hansen; A C Kraan; B S Nilsson; A Kyriakis; C Markou; E Simopoulou; A Vayaki; K Zachariadou; A Blondel; J C Brient; F Machefert; A Rougé; H L Videau; V Ciulli; E Focardi; G Parrini; A Antonelli; M Antonelli; G Bencivenni; F Bossi; G Capon; F Cerutti; V Chiarella; P Laurelli; G Mannocchi; G P Murtas; L Passalacqua; J Kennedy; J G Lynch; P Negus; V O'Shea; A S Thompson; S Wasserbaech; R J Cavanaugh; S Dhamotharan; C Geweniger; P Hanke; V Hepp; E E Kluge; A Putzer; H Stenzel; K Tittel; M Wunsch; R Beuselinck; W Cameron; G Davies; P J Dornan; M Girone; N Marinelli; J Nowell; S A Rutherford; J K Sedgbeer; J C Thompson; R White; V M Ghete; P Girtler; E Kneringer; D Kuhn; G Rudolph; E Bouhova-Thacker; C K Bowdery; D P Clarke; G Ellis; A J Finch; F Foster; G Hughes; R W L Jones; M R Pearson; N A Robertson; T Sloan; M Smizanska; O van der Aa; C Delaere; G Leibenguth; V Lemaître; U Blumenschein; F Hölldorfer; K Jakobs; F Kayser; A S Müller; B Renk; H G Sander; S Schmeling; H W Wachsmuth; C Zeitnitz; T Ziegler; A Bonissent; P Coyle; C Curtil; A Ealet; D Fouchez; P Payre; A Tilquin; F Ragusa; A David; H Dietl; G Ganis; K Hüttmann; G Lütjens; W Männer; H G Moser; R Settles; M Villegas; G Wolf; J Boucrot; O Callot; M Davier; L Duflot; J F Grivaz; P Heusse; A Jacholkowska; L Serin; J J Veillet; P Azzurri; G Bagliesi; T Boccali; L Foà; A Giammanco; A Giassi; F Ligabue; A Messineo; F Palla; G Sanguinetti; A Sciabà; G Sguazzoni; P Spagnolo; R Tenchini; A Venturi; P G Verdini; O Awunor; G A Blair; G Cowan; A García-Bellido; M G Green; T Medcalf; A Misiejuk; J A Strong; P Teixeira-Dias; R W Clifft; T R Edgecock; P R Norton; I R Tomalin; J J Ward; B Bloch-Devaux; D E Boumediene; P Colas; B Fabbro; E Lançon; M C Lemaire; E Locci; P Pérez; J Rander; B Tuchming; B Vallage; A M Litke; G Taylor; C N Booth; S Cartwright; F Combley; P N Hodgson; M H Lehto; L F Thompson; A Böhrer; S Brandt; C Grupen; J Hess; A Ngac; G Prange; C Borean; G Giannini; H He; J Pütz; J E Rothberg; S R Armstrong; K Berkelman; K Cranmer; D P S Ferguson; Y Gao; S González; O J Hayes; H Hu; S Jin; J Kile; P A McNamara; J Nielsen; Y B Pan; J H Von Wimmersperg-Töller; W Wiedenmann; J Wu; S L Wu; X Wu; G Zobernig; G Dissertori

2004-01-01

77

Capillary breakup of Discontinuously Rate Thickening Suspensions  

E-print Network

In this study, we investigated the behavior of Discontinuously Rate Thickening Suspensions (DRTS) in capillary breakup, where a thin suspension filament breaks up under the action of surface tension forces. We performed ...

Zimoch, Pawel

2012-01-01

78

Note on the Transmutation Function for Deuterons  

Microsoft Academic Search

We consider the effect of the finite size and ready polarizability of the deuteron on the probability of transmutations involving the capture of the neutron. These have as a consequence that the Coulomb repulsion of the nucleus is less effective than for alpha-particles or protons, and that the corresponding transmutation functions increase less rapidly with deuteron energy. We treat the

J. R. Oppenheimer; M. Phillips

1935-01-01

79

On the breakup of viscous liquid threads  

NASA Technical Reports Server (NTRS)

A one-dimensional model evolution equation is used to describe the nonlinear dynamics that can lead to the breakup of a cylindrical thread of Newtonian fluid when capillary forces drive the motion. The model is derived from the Stokes equations by use of rational asymptotic expansions and under a slender jet approximation. The equations are solved numerically and the jet radius is found to vanish after a finite time yielding breakup. The slender jet approximation is valid throughout the evolution leading to pinching. The model admits self-similar pinching solutions which yield symmetric shapes at breakup. These solutions are shown to be the ones selected by the initial boundary value problem, for general initial conditions. Further more, the terminal state of the model equation is shown to be identical to that predicted by a theory which looks for singular pinching solutions directly from the Stokes equations without invoking the slender jet approximation throughout the evolution. It is shown quantitatively, therefore, that the one-dimensional model gives a consistent terminal state with the jet shape being locally symmetric at breakup. The asymptotic expansion scheme is also extended to include unsteady and inerticial forces in the momentum equations to derive an evolution system modelling the breakup of Navier-Stokes jets. The model is employed in extensive simulations to compute breakup times for different initial conditions; satellite drop formation is also supported by the model and the dependence of satellite drop volumes on initial conditions is studied.

Papageorgiou, Demetrios T.

1995-01-01

80

Spin-manipulating polarized deuterons  

SciTech Connect

Spin dynamics of polarized deuteron beams near depolarization resonances, including a new polarization preservation concept based on specially-designed multiple resonance crossings, has been tested in a series of experiments in the COSY synchrotron. Intricate spin dynamics with sophisticated pre-programmed patterns as well as effects of multiple crossings of a resonance were studied both theoretically and experimentally with excellent agreement. Possible applications of these results to preserve, manipulate and spin-flip polarized beams in synchrotrons and storage rings are discussed.

Morozov, V S; Krisch, A D; Leonova, M A; Raymond, R S; Sivers, D W; Wong, V K; Hinterberger, F; Kondratenko, A M

2011-03-01

81

Streak breakup in turbulent boundary layers  

NASA Astrophysics Data System (ADS)

Direct numerical simulations are used to compute the evolution of a single streak in a laminar boundary layer (Re* = 450) and a turbulent boundary on a flat plate at zero pressure gradient (Re* = 900). The single streak is formed through fluid injection at the wall as in Acarlar and Smith (1987). It is found that the single streak undergoes an instability resulting in the formation of hairpin vortices. The resulting flow field is in very good agreement with the experimental results of Acarlar and Smith (1987). The instability can be explained through an Orr-Sommerfeld analysis of the velocity profile on the plane of symmetry of the streak. The predicted wavelength and eigenfunctions are in very good agreement with those obtained from the simulations. Application of the same analysis to streaks in a fully turbulent boundary layer reveal as good an agreement. It is argued that this instability is the basic mechanism responsible for streak breakup. Acarlar, M.S. and Smith, C.R., 1987. A study of hairpin vortices in a laminar boundary layer. Part 2. Hairpin vortices generated by fluid injection. J. Fluid Mech., 175, pp. 43-83.

Haritonidis, Joseph H.; Skote, Martin

1999-11-01

82

Preventing alternans-induced spiral wave breakup in cardiac tissue: An ion-channel-based approach  

NASA Astrophysics Data System (ADS)

The detailed processes involved in spiral wave breakup, believed to be one major mechanism by which tachycardia evolves into fibrillation, are still poorly understood. This has rendered difficult the proper design of an efficient and practical control stimulus protocol to eliminate such events. In order to gain new insights into the underlying electrophysiological and dynamical mechanisms of breakup, we applied linear perturbation theory to a steadily rotating spiral wave in two spatial dimensions. The tissue was composed of cells modeled using the Fenton-Karma equations whose parameters were chosen to emphasize alternans as a primary mechanism for breakup. Along with one meandering mode, not just one but several unstable alternans modes were found with differing growth rates, frequencies, and spatial structures. As the conductance of the fast inward current was increased, the instability of the modes increased, consistent with increased meandering and propensity for spiral breakup in simulations. We also explored a promising new approach, based on the theory, for the design of an energy efficient electrical stimulus protocol to control spiral wave breakup. The novelty lies in addressing the problem directly at the ion channel level and taking advantage of the inherent two dimensional nature of the rotating wave. With the help of the eigenmode method, we were able to calculate the exact timing and amplitude of the stimulus, and locate it optimally to maximize efficiency. The analysis led to a special-case example that demonstrated that a single, properly timed stimulus can have a global effect, suppressing all growing alternans modes over the entire tissue, thus inhibiting spiral wave breakup.

Allexandre, D.; Otani, N. F.

2004-12-01

83

Spin-Flipping Polarized Deuterons At COSY  

NASA Astrophysics Data System (ADS)

We recently stored a 1.85 GeV/c vertically polarized deuteron beam in the COSY Ring in Jülich; we then spin-flipped it by ramping a new air-core rf dipole's frequency through an rf-induced spin resonance to manipulate the polarization direction of the deuteron beam. We first experimentally determined the resonance's frequency and set the dipole's rf voltage to its maximum; then we varied its frequency ramp time and frequency range. We used the EDDA detector to measure the vector and tensor polarization asymmetries. We have not yet extracted the deuteron's tensor polarization spin-flip parameters from the measured data, since our short run did not provide adequate tensor analyzing-power data at 1.85 GeV/c. However, with a 100 Hz frequency ramp and our longest ramp time of 400 s, the deuterons' vector polarization spin-flip efficiency was 48±1%.

Yonehara, K.; Krisch, A. D.; Morozov, V. S.; Raymond, R. S.; Wong, V. K.; Bechstedt, U.; Gebel, R.; Lehrach, A.; Lorenz, B.; Maier, R.; Prasuhn, D.; Schnase, A.; Stockhorst, H.; Eversheim, D.; Hinterberger, F.; Rohdjess, H.; Ulbrich, K.; Scobel, W.

2004-02-01

84

Temporal properties of secondary drop breakup in the bag-stamen breakup regime  

NASA Astrophysics Data System (ADS)

The situation of liquid drop bag-stamen breakup in a continuous air jet flow is investigated by a high speed camera. Test liquids include water, ethanol, and various glycerol mixtures. First, the morphology of bag-stamen breakup is observed and analyzed. The bag-stamen breakup range is found to be in good agreement with the model obtained by Rayleigh-Taylor instability. Then the disk and stamen deformation properties, the fragment average size, and size distribution of ring and stamen are researched in detail, respectively.

Zhao, Hui; Liu, Hai-Feng; Xu, Jian-Liang; Li, Wei-Feng; Lin, Kuang-Fei

2013-05-01

85

Deuteron bremsstrahlung-weighted photonuclear sum rule  

SciTech Connect

The various contributions to the deuteron bremsstrahlung-weighted photonuclear sum rule sigma/sub -1/ are analyzed. It is shown that the unretarded normal L = 1 sum rule is model independent and that retardation, higher multipoles, and interaction effects are negligible. An accurate estimation of sigma/sub -1/ is provided by the knowledge of the charge deuteron radius and of the spin gyromagnetic factors of the proton and of the neutron.

Bohigas, O.; Lipparini, E.

1987-11-01

86

Experimental Study of Melt Jet Breakup in Water  

Microsoft Academic Search

In the present study, the jet breakup characteristics of molten material is experimentally investigated in nonboiling condition using Wood's metal to isolate the key features of jet breakup phenomenon from the conjugated nature of melt breakup and steam generation. The experimental apparatus consists mainly of melt generating furnace and melt crucible equipped with variable nozzle diameter, a rectangular water tank

Kwang Hyun BANG; Jong Myung KIM; Dong Ha KIM

2003-01-01

87

Breakup of finite thickness viscous shell microbubbles by ultrasound: A simplified zero-thickness shell model  

PubMed Central

A simplified three-dimensional (3-D) zero-thickness shell model was developed to recover the non-spherical response of thick-shelled encapsulated microbubbles subjected to ultrasound excitation. The model was validated by comparison with previously developed models and was then used to study the mechanism of bubble break-up during non-spherical deformations resulting from the presence of a nearby rigid boundary. The effects of the shell thickness and the bubble standoff distance from the solid wall on the bubble break-up were studied parametrically for a fixed insonification frequency and amplitude. A diagram of bubble shapes versus the normalized shell thickness and wall standoff was derived, and the potential bubble shapes at break-up from reentrant jets were categorized resulting in four distinct zones. PMID:23556560

Hsiao, Chao-Tsung; Chahine, Georges L.

2013-01-01

88

Role of pion exchange in ? meson photoproduction on the deuteron  

NASA Astrophysics Data System (ADS)

Incoherent ? photoproduction on the deuteron is studied, with the main emphasis on the role of final-state interactions. In addition to the previously studied mechanisms of N N and ? N rescatterings, the role of an intermediate pion exchange is considered in detail, where first a pion is photoproduced on one nucleon and then rescatters into an ? meson on the other, the spectator nucleon. It is found that the role of this pion-mediated contribution is comparable in size to that of ? N rescattering. Results for total and semi-inclusive differential cross sections and associated polarization observables are presented. In particular, polarization observables show significant sensitivity to final-state interactions.

Fix, A.; Arenhövel, H.; Levchuk, M.; Tammam, M.

2015-01-01

89

[Defence mechanisms and coping strategies in men and women: a comparative and structural study based on the artistic production of people suffering from a break-up of their life project].  

PubMed

A comparative study of men and women suffering from a break-up of their life project allowed us examining the typically female and male manners to cope with trauma, anxiety, guilt, depression and internal destructivity. In a first stage, an exploratory study was focussed on 206 subjects, belonging to several clinical subgroups: people living in great precarity and long-term unemployed people, asylum seekers and refugees, drug addicts, prisoners and people coming out of prison. Secondly, arts therapeutic sessions were proposed with the aim of helping the participants finding an outlet to their situation. The artistic production (drawings and stories induced by music) was analysed with the help of original rating scales, constructed in a phenomenological and structural perspective. We will present a synthesis of our qualitative observations, as well as some results of typological and structural studies, computed with the help of non parametric statistical procedures on the data of N = 93 participants. The results allow us pointing to gender differences and defining typically male and female coping styles. Differential indications for psychotherapy can be extracted from these analyses. PMID:24437072

Schiltz, L; Ciccarello, A; Ricci-Boyer, L; Schiltz, J

2013-01-01

90

PROSPECTS FOR ACCELERATION OF DEUTERONS AND HELIONS.  

SciTech Connect

In order to study the spin structure of the neutron at high energy, a beam rich in polarized neutrons needs to be developed. The neutron has no charge and cannot be accelerated, so either deuterons or helions must be considered. When it comes to spin manipulation and stability of the polarization in a circular accelerator, it is the anomalous part of the magnetic moment which is important. If the anomaly is too small, then manipulation becomes difficult as in the case of deuterons--spin rotators and Siberian snakes become ineffective. {sup 3}He nuclei appear to be the easiest choice for a polarized neutron beam. In this paper I discuss the prospects for both helions and deuterons as polarized beams in RHIC or in an electron-ion collider.

MACKAY,W.W.

2007-09-10

91

Prospects for Acceleration of Deuterons and Helions  

SciTech Connect

In order to study the spin structure of the neutron at high energy, a beam rich in polarized neutrons needs to be developed. The neutron has no charge and cannot be accelerated, so either deuterons or helions must be considered. When it comes to spin manipulation and stability of the polarization in a circular accelerator, it is the anomalous part of the magnetic moment which is important. If the anomaly is too small, then manipulation becomes difficult as in the case of deuterons--spin rotators and Siberian snakes become ineffective. {sup 3}He nuclei appear to be the easiest choice for a polarized neutron beam. In this paper I discuss the prospects for both helions and deuterons as polarized beams in RHIC or in an electron-ion collider.

MacKay, W. W. [Brookhaven National Laboratory, Upton, NY 11973 (United States)

2008-02-06

92

Comparisons of debris environment model breakup models  

NASA Astrophysics Data System (ADS)

This paper presents a comparison of current spacecraft breakup models used in orbital (space) debris computational environment models. The breakup models to be compared come from the NASA EVOLVE (Evolutionary) model long term debris model, the IMPACT code developed by Aerospace Corp., and the Fragmentation Algorithms for Satellite Targets (FAST) developed by Kaman Sciences. The comparison will show the methodologies and results obtained for each model such as mass versus fragment number distributions. Implications for debris cloud formation will be discussed in terms of the environments produced. No attempt is made to recommend any one model over the other as each were designed and employed for specific purposes in the environment models they are part of or contribute to. The comparisons are intended to provide researchers both quantitative and qualitative information on the models for use in their own research activities.

Jonas, F.; Yates, K.; Evans, R.

1993-01-01

93

A mesonic analog of the deuteron  

NASA Astrophysics Data System (ADS)

Using the LAMP model for nuclear quark structure, we calculate the binding energy and quark structure of a B meson merging with a D meson. Our variational calculation shows that a molecular, deuteron-like state structure changes rather abruptly, as the separation between the two mesons decreases, and at a separation of about 0.14 fm, the hadronic system transforms into a four-quark bound state, although one maintaining an internal structure rather than that of a four-quark "bag." Unlike the deuteron, pion exchange does not provide any contribution to the ? 150 MeV binding.

Silbar, Richard R.; Goldman, T.

2014-12-01

94

Beam Breakup Effects in Dielectric Based Accelerators  

SciTech Connect

The dynamics of the beam in structure-based wakefield accelerators leads to beam stability issues not ordinarily found in other machines. In particular, the high current drive beam in an efficient wakefield accelerator loses a large fraction of its energy in the decelerator structure, resulting in physical emittance growth, increased energy spread, and the possibility of head-tail instability for an off axis beam, all of which can lead to severe reduction of beam intensity. Beam breakup (BBU) effects resulting from parasitic wakefields provide a potentially serious limitation to the performance of dielectric structure based wakefield accelerators as well. We report on experimental and numerical investigation of BBU and its mitigation. The experimental program focuses on BBU measurements at the AWA facility in a number of high gradient and high transformer ratio wakefield devices. New pickup-based beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable. The numerical part of this research is based on a particle-Green's function beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the results of detailed experimental measurements with the accurate numerical results and to design an external FODO channel for the control of the beam in the presence of strong transverse wakefields.

Schoessow, P.; Kanareykin, A. [Euclid Techlabs LLC, Solon, OH 44139 (United States); Jing, C. [Euclid Techlabs LLC, Solon, OH 44139 (United States); Argonne National Laboratory, IL (United States); Kustov, A. [Dynamics Software, Helsinki (Finland); Altmark, A. [Electrotechnical University Eltech 'LETI', St. Petersburg (Russian Federation); Power, J. G.; Gai, W. [Argonne National Laboratory, IL (United States)

2009-01-22

95

Cold nuclear matter effects on J/{psi} production as constrained by deuteron-gold measurements at {radical}(s{sub NN})=200 GeV  

SciTech Connect

We present a new analysis of J/{psi} production yields in deuteron-gold collisions at {radical}(s{sub NN})=200 GeV using data taken from the PHENIX experiment in 2003 and previously published in S. S. Adler et al. [Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/{psi} data taken in 2005 are used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors (R{sub dAu}). A suppression of J/{psi} in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial-state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/{psi} (or precursor) breakup cross section is added. Breakup cross sections of {sigma}{sub breakup}=2.8{sub -1.4}{sup +1.7} (2.2{sub -1.5}{sup +1.6}) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross-section values are consistent within large uncertainties with the 4.2{+-}0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.

Adare, A.; Bickley, A. A.; Ellinghaus, F.; Kinney, E.; Seele, J.; Wysocki, M. [University of Colorado, Boulder, Colorado 80309 (United States); Adler, S. S.; Aronson, S. H.; Azmoun, B.; Belikov, S.; David, G.; Desmond, E. J.; Franz, A.; Haggerty, J. S.; Harvey, M.; Johnson, B. M.; Kistenev, E.; Kroon, P. J.; Lynch, D.; Makdisi, Y. I. [Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)] (and others)

2008-02-15

96

Modeling mud flocculation using variable collision and breakup efficiencies  

NASA Astrophysics Data System (ADS)

Solution of the Winterwerp (1998) floc growth and breakup equation yields time dependent median floc size as an outcome of collision driven floc growth and shear induced floc breakage. The formulation is quite nice in that it is an ODE that yields fast solution for median floc size and can be incorporated into sediment transport models. The Winterwerp (1998) floc size equation was used to model floc growth and breakup data from laboratory experiments conducted under both constant and variable turbulent shear rate (Keyvani 2013). The data showed that floc growth rate starts out very high and then reduces with size to asymptotically approach an equilibrium size. In modeling the data, the Winterwerp (1998) model and the Son and Hsu (2008) variant were found to be able to capture the initial fast growth phase and the equilibrium state, but were not able to well capture the slow growing phase. This resulted in flocs reaching the equilibrium state in the models much faster than the experimental data. The objective of this work was to improve the ability of the general Winterwerp (1998) formulation to better capture the slow growth phase and more accurately predict the time to equilibrium. To do this, a full parameter sensitivity analysis was conducted using the Winterwerp (1998) model. Several modifications were tested, including the variable fractal dimension and yield strength extensions of Son and Hsu (2008, 2009). The best match with the in-house data, and data from the literature, was achieved using floc collision and breakup efficiency coefficients that decrease with floc size. The net result of the decrease in both of these coefficients is that floc growth slows without modification to the equilibrium size. Inclusion of these new functions allows for substantial improvement in modeling the growth phase of flocs in both steady and variable turbulence conditions. The improvement is particularly noticeable when modeling continual growth in a decaying turbulence field similar to what might be experienced in a river mouth jet. Inclusion of the functions does, however, result in problems with capturing rapid floc breakage due to a stepwise increase in turbulent shear. References Keyvani, A. (2013). Flocculation processes in river mouth fluvial to marine transitions. Ph.D. dissertation, University of Houston. Son, M. & Hsu, T.J. (2008). Flocculation model of cohesive sediment using variable fractal dimension. Environmental Fluid Mechanics, 8(1), 55-71. Son, M. & Hsu, T.J. (2009). The effect of variable yield strength and variable fractal dimension on flocculation of cohesive sediment. Water Research, 43(14), 3582 - 3592. Winterwerp, J. C. (1998). A simple model for turbulence induced flocculation of cohesive sediment. Journal of Hydraulic Research, 36(3), 309-326.

Strom, K.; Keyvani, A.

2013-12-01

97

Multipass Beam Breakup in Energy Recovery Linacs  

SciTech Connect

This paper is a compilation of several presentations on multipass beam breakup (BBU) in energy recovery linacs (ERL) given at the 32nd Advanced ICFA Beam Workshop on ERLs. The goal of this paper is to summarize the progress achieved in analytical, numerical, and experimental studies of the instability and outline available and proposed BBU mitigation techniques. In this paper, a simplified theory of multipass BBU in recirculating linacs is presented. Several BBU suppression techniques and their working principles are discussed. The paper presents an overview of available BBU codes. Results of experimental studies of multipass BBU at the Jefferson Laboratory (JLab) FEL Upgrade are described.

Eduard Pozdeyev; Christopher Tennant; Joseph Bisognano; M Sawamura; R. Hajima; T.I. Smith

2005-03-19

98

Polar lake circulation during ice break-up  

NASA Astrophysics Data System (ADS)

An extensive dataset on lake physical properties has been collected during the final stage of the ice-covered period in May-June 2013 in polar Lake Kilpisjärvi, Finland. The data reveal several important features of lake dynamics, which shed new light on the mechanism of ice cover break-up and ice melting in lakes and marginal seas. CTD transects with high spatial resolution showed up a 300m-wide upwelling zone in the center of the lake, driven by downslope converging flow of warm waters from open-water 'moat' along the lake shoreline. The resulting radial density gradient, balanced by the Coriolis force, created a lake-wide anti-cyclonically rotating gyre with a measured peak azimuthal velocity of 0.05 m/s. Appreciable marginal heating is driven in polar enclosed basins by high amount of solar radiation and by surface inflow of meltwater. Hence, quasi-geostrophic anticyclonic circulation is suggested to be a general feature of polar lakes, redistributing heat within a water body and potentially accelerating ice melting. In addition, high-resolution records of pressure, current velocities and water temperature revealed under-ice seiches with periods of 10 to 25 min. The ice breakup was associated with 10 times increase of seiche amplitudes under ice. The seiches decayed within 10-15 hours; during this short period, the previously ice-covered lake became ice-free. We suggest that seiche-driven vertical motions of the soft ice sheet contribute significantly to breaking and melting of seasonal ice in enclosed reservoirs.

Kirillin, Georgiy; Forrest, Alexander; Graves, Kelly; Laval, Bernard

2014-05-01

99

Numerical simulation of jet breakup due to amplitude-modulated (AM) disturbance  

Microsoft Academic Search

In order to characterize the mechanics of jet breakup, the finite volume formulations were employed to solve the Navier-Stokes equations and continuity equation of jet. The volume of fluid(VOF) method was used to track the free surface of jet. The spray process of the molten Pb63Sn37 alloy was simulated based on the mathematical model by means of FLUENT code. The

Jun LUO; Le-hua QI; Li LI; Fang YANG; Xiao-shan JIANG

2008-01-01

100

Breakup Effects on University Students' Perceived Academic Performance  

ERIC Educational Resources Information Center

The Problem: Problems that might be expected to affect perceived academic performance were studied in a sample of 283 university students. Results: Breakup Distress Scale scores, less time since the breakup and no new relationship contributed to 16% of the variance on perceived academic performance. Variables that were related to academic…

Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

2012-01-01

101

Modeling of Turbulence Effects on Liquid Jet Atomization and Breakup  

NASA Technical Reports Server (NTRS)

Recent experimental investigations and physical modeling studies have indicated that turbulence behaviors within a liquid jet have considerable effects on the atomization process. This study aims to model the turbulence effect in the atomization process of a cylindrical liquid jet. Two widely used models, the Kelvin-Helmholtz (KH) instability of Reitz (blob model) and the Taylor-Analogy-Breakup (TAB) secondary droplet breakup by O Rourke et al, are further extended to include turbulence effects. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic scales and the initial flow conditions. For the secondary breakup, an additional turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. The drop size formed from this breakup regime is estimated based on the energy balance before and after the breakup occurrence. This paper describes theoretical development of the current models, called "T-blob" and "T-TAB", for primary and secondary breakup respectivety. Several assessment studies are also presented in this paper.

Trinh, Huu P.; Chen, C. P.

2005-01-01

102

Numerical simulation of turbulent jet primary breakup in Diesel engines  

E-print Network

Numerical simulation of turbulent jet primary breakup in Diesel engines Peng Zeng1 Marcus Herrmann and Aerospace Engineering Arizona State University "Micro-Macro Modelling and Simulation of Liquid-Vapour Flows" IRMA Strasbourg, 23.Jan.2008 #12;Introduction DNS of Primary Breakup in Diesel Injection Phase

Helluy, Philippe

103

Persistence of Memory in Drop Breakup: The Breakdown of Universality  

Microsoft Academic Search

A low-viscosity drop breaking apart inside a viscous fluid is encountered when air bubbles, entrained in thick syrup or honey, rise and break apart. Experiments, simulations, and theory show that the breakup under conditions in which the interior viscosity can be neglected produces an exceptional form of singularity. In contrast to previous studies of drop breakup, universality is violated so

Pankaj Doshi; Itai Cohen; Wendy W. Zhang; Michael Siegel; Peter Howell; Osman A. Basaran; Sidney R. Nagel

2003-01-01

104

Mixing and Dispersion of Immiscible Fluids: Stretching and Breakup in Chaotic Flows.  

NASA Astrophysics Data System (ADS)

We investigate the stretching and breakup of a drop freely suspended in a viscous fluid undergoing chaotic advection. Droplets stretch into filaments acted on by a complex flow history leading to exponential length increase, folding, and eventual breakup; following breakup, chaotic stirring disperses the fragments throughout the flow. These events are studied by experiments conducted in a time-periodic two-dimensional low Reynolds number chaotic flow. Studies are restricted to viscosity ratios p such that 0.01 < p < 2.8. The experimental results are highly reproducible and illustrate new qualitative aspects with respect to the case of stretching and breakup in linear flows. For example, breakup near folds is associated with a change of sign in stretching rate; this mode of breakup leads to the formation of rather large drops. The dominant breakup mechanism, however, is capillary wave instabilities in highly stretched filaments. Other modes of breakup, such as 'necking', 'end-pinching', and 'fold-pinching' occur as well. We find that drops in low-viscosity-ratio systems, p < 1, extend relatively little, O(10 ^1-10^2), before they break, producing an array of uniformly spaced drops (also known as mother drops) with as many as 19 satellites and sub-satellites in between. Large drop fragments, typically the product of end-pinching and fold-pinching, may again undergo a succession of breakup events, usually about 2 -4 times. Drops in systems with p > 1, on the other hand, stretch substantially, O(10 ^1-10^4), before they break producing small fragments that rarely break again. The number of satellites in between two mother drops in these systems never exceeds 5. The experimental results are interpreted in terms of a simple model assuming that moderately extended filaments behave passively; this is an excellent approximation especially for low-viscosity-ratio drops, p < 1. The dynamics of the disturbances on the surface of the extending filament, and consequently the sizes of the resulting mother drops, are computed by means of linear stability theory. The linear stability theory, however, fails to capture the evolution of the undulated filament once the large curvature around the neck region develops. Thus, we resort to a different technique, i.e., boundary integral method, to obtain the exact pinch-off location and simulate the subsequent fluid motions which lead to the formation of satellite drops. Data from 2000-3000 thousands of droplets measured in each experiment after a long time indicate that the mean drop size decreases as the viscosity ratio increases. The repetitive nature of stretching and folding, as well as the self-repeating nature of the breakup process, suggests self-similarity. We find that, indeed, upon scaling, the drop size distributions corresponding to different viscosity ratios can be collapsed into a master curve.

Tjahjadi, Mahari

105

Practical Methods for Studying Collisional Breakup  

NASA Astrophysics Data System (ADS)

The quantum theory of three-body breakup in Coulomb systems, formulated in the early sixties, has formed the basis of a considerable body of theoretical analysis of low energy electron impact ionization. Although aspects of this theory have been incorporated into various perturbative and distorted-wave treatments, the formal theory has not provided a viable comupational approach to a first-principles treatment of ionization, due to the complicated nature of the boundary conditions for three-body breakup in Coulomb systems and the fact that they are only known in the far asymptotic region. Exterior complex scaling allows one to solve the Schrödinger equation without explicit imposition of asymptotic boundary conditions. This approach has produced the first triple differential cross sections for e-H ionization that are in complete agreement with absolute measurements[1]. In this talk, I will review the essential aspects of this approach and present new results on double differential cross sections for e-H ionization. I will also discuss some new methods for extracting dynamical information from numerically obtained wave functions that are more efficient than the flux operator approach we previously employed. These methods allow us to explore ionization in the threshold region and open the way to calculations on systems with more than two electrons, where new physical effects can be studied. [1] T. N. Rescigno, M. Baertschy, W. A. Isaacs and C. W. McCurdy, Science 286, 2474 (1999)

Rescigno, T. N.

2000-10-01

106

New Candidates for Recent Asteroid Breakups  

NASA Astrophysics Data System (ADS)

Asteroids in our solar system formed in a dynamically quiescent disk, but their orbits became gravitationally stirred enough by Jupiter to lead to high-speed collisions. As a result, several dozen large asteroids have been disrupted by impacts over the past several gigayears and have produced groups of fragments called asteroid families. Here we report three new candidates for asteroid families that were formed by collisions occurring in the last 1 Myr. According to our modeling of the past orbital histories of known cluster members, we estimate that the Emilkowalski, 1992 YC2, and Lucascavin clusters are 220+/-30, 50-250, and 300-800 kyr old, respectively. Together with the previously identified Datura cluster, estimated to be 450+/-50 kyr old, they are the most recent asteroid breakups ever discovered in the main belt. Astronomical observations of identified family members can be used to better understand impact physics, asteroid composition, and surface-aging processes. Discovered breakups may also be important sources of interplanetary dust.

Nesvorný, D.; Vokrouhlický, D.

2006-11-01

107

Polymeric filament thinning and breakup in microchannels  

E-print Network

The effects of elasticity on filament thinning and breakup are investigated in microchannel cross flow. When a viscous solution is stretched by an external immiscible fluid, a low 100 ppm polymer concentration strongly affects the breakup process, compared to the Newtonian case. Qualitatively, polymeric filaments show much slower evolution, and their morphology features multiple connected drops. Measurements of filament thickness show two main temporal regimes: flow- and capillary-driven. At early times both polymeric and Newtonian fluids are flow-driven, and filament thinning is exponential. At later times, Newtonian filament thinning crosses over to a capillary-driven regime, in which the decay is algebraic. By contrast, the polymeric fluid first crosses over to a second type of flow-driven behavior, in which viscoelastic stresses inside the filament become important and the decay is again exponential. Finally, the polymeric filament becomes capillary-driven at late times with algebraic decay. We show that the exponential flow thinning behavior allows a novel measurement of the extensional viscosities of both Newtonian and polymeric fluids.

P. E. Arratia; J. P. Gollub; D. J. Durian

2007-03-15

108

Development of the Explosion Breakup Model for Space Debris  

NASA Astrophysics Data System (ADS)

This paper will examine the applicability of the National Aeronautics and Space Administration (NASA) standard breakup model 2000 revision to explosion breakup in space. The cylinder specimens of stainless steel with smooth were explosively expanded to fragmentation. The driver was a column of the high explosive PETN inserted into the central bore and initiated by exploding a bundle of fine copper wires using a discharge current from a high-voltage capacitor bank. Expansion rate and the collection fragments will be analyzed based on the method used in the NASA standard breakup model 2000 revision to be compared with the explosion model adopted in the NASA standard breakup model. And this paper evaluated NASA standard breakup model 2000 revision model about size distribution, average cross-section area, area mass ratio distribution, delta velocity distribution.

Hata, Hidehiro; Hiroe, Tetsuyuki; Fujiwara, Kazuhito

109

Incoherent Pion Production in Neutrino - Deuteron Reactions  

E-print Network

Within the multiple scattering formulation, the incoherent pion production in neutrino-deuteron reactions at energies near the $\\Delta(1232)$ resonance is investigated. The calculations include an impulse term and one-loop contributions from nucleon-nucleon ($NN$) and pion-nucleon ($\\pi N$) final state interactions. The input pion production amplitudes and $\\pi N$ scattering amplitudes are generated from a dynamical model which describes very extensive data of $\\pi N$ scattering and both the electromagnetic and the weak pion production reactions on the nucleon. The $NN$ scattering amplitudes are generated from the Bonn potential. The validity of the developed calculation procedures is established by giving a reasonably good description of the data of pion photo-production on the deuteron. The constructed model is then applied to predict the cross sections of $\

Jia-Jun Wu; T. Sato; T. -S. H. Lee

2014-12-07

110

Sikuliqiruq: Ice dynamics of the Meade river - Arctic Alaska, from freezeup to breakup from time-series ground imagery  

USGS Publications Warehouse

Ice formation and breakup on Arctic rivers strongly influence river flow, sedimentation, river ecology, winter travel, and subsistence fishing and hunting by Alaskan Natives. We use time-series ground imagery ofthe Meade River to examine the process at high temporal and spatial resolution. Freezeup from complete liquid cover to complete ice cover ofthe Meade River at Atqasuk, Alaska in the fall of 2008 occurred in less than three days between 28 September and 2 October 2008. Breakup in 2009 occurred in less than two hours between 23:47 UTC on 23 May 2009 and 01:27 UTC on 24 May 2009. All times in UTC. Breakup in 2009 and 2010 was ofthe thermal style in contrast to the mechanical style observed in 1966 and is consistent with a warming Arctic. ?? 2010 Taylor & Francis.

Beck, R.A.; Rettig, A.J.; Ivenso, C.; Eisner, W.R.; Hinkel, K.M.; Jones, B.M.; Arp, C.D.; Grosse, G.; Whiteman, D.

2010-01-01

111

Neutron-deuteron scattering in configuration space  

NASA Astrophysics Data System (ADS)

A new computational method for solving the configuration-space Faddeev equations for the breakup scattering problem [1] has been applied to consider nd scattering both below and above two-body threshold. To perform numeric calculations for arbitrary nuclear potential and with arbitrary number of partial waves retained, we use approach proposed in [2]. The calculations of the inelasticity and phase-shift, as well the breakup amplitudes for nd scattering for various lab energies were performed with the charge independent AV14 potential. The results are compared with those of Bochum and Pisa group [3]. 1. V.M. Suslov and B. Vlahovic, Phys. Rev. C 69, 044003 (2004). 2. S.P. Merkuriev, C. Gignoux and A. Laverne, Ann. Phys. 99, 30 (1976). 3. W. Gl"ockle, H. Witala, D. H"uber, H. Kamada, J. Golak, Physics Report, 274, 107 (1996).

Suslov, Vladimir; Braun, Mikhail; Vlahovic, Branislav

2006-04-01

112

Coupling between a deuteron and a lattice  

E-print Network

We recently put forth a new fundamental lattice Hamiltonian based on an underlying picture of electrons and deuterons as elementary Dirac particles. Within this model there appears a term in which lattice vibrations are coupled to internal nuclear transitions. This is interesting as it has the potential to provide a connection between experiment and models that describe coherent energy transfer between two-level systems and an oscillator. In this work we describe a calculation of the coupling matrix element in the case of the deuteron based on the old empirical Hamada-Johnston model for the nucleon-nucleon interaction. The triplet S and D states of the the deuteron in the rest frame couples to a singlet P state through this new interaction. The singlet P state in this calculation is a virtual state with an energy of 125 MeV, and a coupling matrix element for $z$-directed motion given by $2.98 \\times 10^{-3} ~M_J c \\hat{P}_z$.

P. L. Hagelstein; I. U. Chaudhary

2012-04-08

113

Bromine and iodine excitation-function measurements with protons and deuterons at 3--17 MeV  

SciTech Connect

We report nuclear excitation functions for the reactions [sup 79]Br[([ital p],[ital n])+([ital d],2[ital n])][sup 79]Kr, [sup 81]Br[([ital p],[ital n])+ ([ital d],2[ital n])][sup 81]Br, [sup 81]Br([ital d],[ital p])[sup 82]Br, and [sup 127]I[([ital p],[ital n])+([ital d],2[ital n])][sup 127]Xe. The measurements were made from reaction threshold to 17 MeV with the Lawrence Livermore National Laboratory's Tandem Van de Graaff accelerator using the stacked-foil method. The [sup 79]Br([ital d],2[ital n])[sup 79]Kr and the [sup 81]Br excitation functions are the first reported. The targets consisted of the halides dispersed in the plastic Kapton. The activated targets were assayed using [gamma] counting and mass spectrometry. We found that we had to remeasure the gamma intensities for the [sup 79]Kr decay. The excitation functions were modeled using the Hauser-Feshbach statistical-model code STAPRE, using the exciton preequilibrium model. We found a preference for the back-shifted (BS) level density prescription over the use of the Gilbert-Cameron prescription. For BS, the constant [ital K], governing the transition to equilibrium, was taken as 500 to 700 MeV[sup 3]. These values gave preequilibrium fractions consistent with those we obtained from ion-recoil range studies of light ion reactions. In general the modeling agreed well with experiment. For the deuteron induced reactions, we had to allow for deuteron breakup using a microscopic breakup fusion approach developed by Udagawa and Tamura. Our analysis of the stripping reaction, [sup 81]Br([ital d],[ital p])[sup 82]Br, by this procedure is especially noteworthy.

West, H.I. Jr.; Nuckolls, R.M.; Hudson, B.; Ruiz, B.; Lanier, R.G.; Mustafa, M.G. (University of California, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States))

1993-01-01

114

Thermonuclear breakup reactions of light nuclei. I - Processes and effects. [in astrophysic plasmas  

NASA Technical Reports Server (NTRS)

Temperature and density conditions are considered for the occurrence of breakup reactions of light nuclei in astrophysical plasmas. The proton-induced endothermic process is shown to be the principal mechanism for nuclear breakdown in a plasma. The phenomenon occurs at a temperature of about 1 MeV, which is a fraction of the typical binding energy per nucleon in nuclei. The temperature for breakup of He-4 is about twice as large, because of the higher binding energy. Depending on the temperature attained in the plasma, the initial concentration of elements heavier than hydrogen can be depleted. However, if it attains a temperature of about 1 MeV, breaking up the metals (C, N, O, Ne, Mg) but not He-4, an increase in the He-4 abundance by as much as 10 percent can result, since these elements essentially break down to alpha particles.

Guessoum, Nidhal; Gould, Robert J.

1989-01-01

115

Impacts, tillites, and the breakup of Gondwanaland  

NASA Technical Reports Server (NTRS)

Mathematical analysis demonstrates that substantial impact crater deposits should have been produced during the last 2 Gy of Earth's history. Textures of impact deposits are shown to resemble textures of tillites and diamictites of Precambrian and younger ages. The calculated thickness distribution for impact crater deposits produced during 2 Gy is similar to that of tillites and diamictites of 2 Ga or younger. We suggest, therefore, that some tillites/diamictites could be of impact origin. Extensive tillite/diamictite deposits predated continental flood basalts on the interior of Gondwanaland. Significantly, other investigators have already associated impact cratering with flood basalt volcanism and continental rifting. Thus, it is proposed that the breakup of Gondwanaland could have been initiated by crustal fracturing from impacts.

Oberbeck, Verne R.; Marshall, John R.; Aggarwal, Hans

1993-01-01

116

Pion-less effective field theory on low-energy deuteron electrodisintegration  

SciTech Connect

In view of its relation to Big Bang nucleosynthesis and a reported discrepancy between nuclear models and data taken at S-DALINAC, electro-induced deuteron breakup {sup 2}H(e,e{sup '}p)n is studied at momentum transfer q<100 MeV and close to threshold in the low-energy nuclear effective field theory without dynamical pions, EFT({pi} /). The result at next-to-next-to-leading order (N{sup 2}LO) for electric dipole currents and at next-to-leading order (NLO) for magnetic ones converges order-by-order better than quantitatively predicted and contains no free parameter. It is at this order determined by simple, well-known observables. Decomposing the triple differential cross section into the longitudinal-plus-transverse (L+T), transverse-transverse (TT), and longitudinal-transverse interference (LT) terms, we find excellent agreement with a potential-model calculation by Arenhoevel and co-workers, based on the Bonn potential. Theory and data also agree well on {sigma}{sub L+T}. There is however no space on the theory side for the discrepancy of up to 30%(3{sigma}) between theory and experiment in {sigma}{sub LT}. From universality of EFT({pi} /), we conclude that no theoretical approach with the correct deuteron asymptotic wave function can explain the data. Undetermined short-distance contributions that could affect {sigma}{sub LT} enter only at high orders (i.e., at the few-percent level). We notice some issues with the kinematics and normalization of the data reported.

Christlmeier, Stefan [Institut fuer Theoretische Physik (T39), Physik-Department, Technische Universitaet Muenchen, D-85747 Garching (Germany); Griesshammer, Harald W. [Institut fuer Theoretische Physik (T39), Physik-Department, Technische Universitaet Muenchen, D-85747 Garching (Germany); Center for Nuclear Studies, Department of Physics, The George Washington University, Washington DC 20052 (United States)

2008-06-15

117

The breakup length of harmonically stimulated capillary jets  

NASA Astrophysics Data System (ADS)

A simple transfer function that can predict the breakup length of a pressure-modulated capillary jet is rigorously deduced from first principles. In this paper, the initial velocity modulation of a stimulated jet is given in terms of its pressure amplitude by means of a generalized Bernoulli equation, which in turn is connected to the breakup time through a two-mode linear analysis. The predicted breakup length is compared against experimental results with water jets emerging from a thin 1 mm-diameter orifice for different pressure modulations. These experiments agree better with the presented theoretical prediction than with a previously established model.

García, F. J.; González, H.; Castrejón-Pita, J. R.; Castrejón-Pita, A. A.

2014-09-01

118

A novel particle tracking and break-up detection algorithm: application to the turbulent break-up of bubbles  

NASA Astrophysics Data System (ADS)

A new method has been developed to measure experimentally the break-up properties of bubbles. The technique is based on the application of a particle tracking velocimetry algorithm to high-speed video images not only to measure the velocity of the bubbles, but also to detect the break-up events. Thus the algorithm is able to associate every broken bubble with the daughter bubbles formed upon their corresponding break-up. Moreover, the lifetime, as well as the number and size of fragments resulting from the break-up process, can be measured for a large number of bubbles. Statistical processing of the information collected allows us to compute the break-up frequency and daughter size distribution of the bubbles as a function of the bubble size and the mean properties of the base flow. The method has been employed to study the break-up of a cloud of bubbles injected at the central axis of a turbulent water jet. Experimental results for the break-up frequency and daughter bubble size distribution are also presented to illustrate the performance of the technique.

Rodríguez-Rodríguez, Javier; Martínez-Bazán, Carlos; Montañes, José Luis

2003-08-01

119

Strategy to search fragments from breakups in GEO  

NASA Astrophysics Data System (ADS)

This paper proposes a strategy to search fragments from breakups in the Geosynchronous Earth Orbit (GEO) region based upon population prediction and motion prediction by means of ground-based optical observations. Breakup fragments have uncertainties in the states such as their position and motion, or even in their existence. Population prediction and motion prediction resolve those uncertainties. Population prediction evaluates the time-averaged distribution of fragments, whose position at a given time is unknown, in the celestial sphere. Motion prediction evaluates the expected motion of fragments appeared in image series acquired by a telescope's CCD camera. This paper logically describes procedures of the search strategy, and provides mathematical expressions of population prediction and motion prediction. This paper also validates the search strategy via actual observations, in which a confirmed breakup in the GEO region is selected as a target. It is concluded that the proposed strategy is valid even for searching uncataloged fragments from breakups in the GEO region.

Uetsuhara, M.; Hanada, T.; Yamaoka, H.; Yanagisawa, T.; Kurosaki, H.; Kitazawa, Y.

2012-04-01

120

Breakup of double emulsions in wedge-shaped microfluidic channels  

NASA Astrophysics Data System (ADS)

Double emulsion droplets can serve as drug delivery vehicles and individual compartments for chemical reactions, and such materials are relevant to new kinds of microfluidic applications. We study experimentally the dynamics and breakup of double emulsion droplets flowing through poly(dimethylsiloxane) (PDMS) channels. As water-in-oil-in-water (W/O/W) double emulsion droplets flow through such wedge-shaped channels, the breakup of the droplets is controlled by the capillary number and the droplet-to-orifice size ratio. We obtain a phase diagram of droplet breakup morphology from the experimental results, and explain the results via a combination of the capillary instability and thin film dynamics. The phase diagram is useful for predicting and controlling the breakup of the droplet. Finally, differences between results obtained in PDMS channels and capillary channels are discussed.

Li, Jiang; Chen, Haosheng; Stone, Howard A.

2010-11-01

121

[MRO] Capillary Breakup of Discontinuously Rate Thickening Suspensions  

E-print Network

Using discontinuously rate thickening suspensions (DRTS) as a model system, we show that beads-on-a-string morphologies can arise as a result of external viscous drag acting during capillary-driven breakup of a non-Newtonian ...

McKinley, Gareth H.

122

Breakup of a Liquid Drop Falling Through a Quiescent Media: A DNS Study  

NASA Astrophysics Data System (ADS)

The breakup of falling liquid droplets in a stationary media is studied using Direct Numerical Simulations (DNS). An adaptive Volume of Fluid (VOF) method based on an octree Cartesian grid generation is employed, considerably reducing the computational cost. Fragmentations are followed reaching approximately stable clouds of droplets up to 1/1000 of the initial droplet diameter. Three different simulations are performed investigating the influence of the initial E"otv"os number. The mechanism of breakup, one of the most unclear phenomena in multiphase systems is described in detail. The wave growth over the bag, creation and retraction of punctures and ligament formation are presented and results are compared with recent theoretical investigations of (Savva & Bush, J. Fluid. Mech. 626: 211-240.) and (Bermond & Villermaux, J. Fluid. Mech. 524: 121-130.). The roles of Rayleigh-Taylor and Rayleigh-Plateau instabilities on breakup are also described and their influences on further cluster-of-fragments creation are shown. The outcomes can be used to develop current secondary atomization models. Moreover, the results can be used for better understanding of rain drop atomization during precipitation, as well as water droplet atomization in cooling towers.

Jalaal, Maziyar; Mehravaran, Kian

2011-11-01

123

Exotic break-up modes in heavy ion reactions at low energies  

NASA Astrophysics Data System (ADS)

New reaction mechanisms occurring in heavy ion collisions at low energy (10-30 MeV/nucleon) are investigated within the stochastic mean field model. We concentrate on the analysis of ternary breakup events, of dynamical origin, occurring in semicentral reactions, where the formation of excited systems in various conditions of shape and angular momentum is observed. We show how this fragmentation mode may emerge from the combined action of surface (neck) instabilities and angular momentum effects. Interesting perspectives on this mechanism in neutron-rich (or exotic) systems are developing, with the possibility of accessing information on the low-density behavior of the nuclear symmetry energy.

Rizzo, C.; Colonna, M.; Baran, V.; Di Toro, M.

2014-11-01

124

Adult Attachment and the Break-Up of Romantic Relationships  

Microsoft Academic Search

The study of the break-up of romantic relationships was integrated into research on adults' attachment representations. Eighty-three female subjects, currently married mothers of one child, were given the Adult Attachment Interview (AAI; George, Kaplan, & Main, 1985), supplemented with questions about the break-up of relationships with former husbands or boyfriends. Subjects who were classified as Unresolved with respect to loss

Marian J. Bakermans-Kranenburg; Marinus H. van IJzendoora

1997-01-01

125

Breakup of an electrified viscous thread with charged surfactants  

NASA Astrophysics Data System (ADS)

The dynamics and breakup of electrified viscous jets in the presence of ionic surfactants at the interface are investigated theoretically. Axisymmetric configurations are considered and the jet is surrounded by a concentrically placed cylindrical electrode, which is held at a constant voltage potential. The annular region between the jet and the electrode is taken to be a hydrodynamically passive dielectric medium and an electric field is set up there and drives the flow, along with other physical mechanisms including capillary instability and viscous effects. The jet fluid is taken to be a symmetric electrolyte and proper modeling of the cationic and anionic species is used by considering the Nernst-Planck equations in order to find the volume charge density that influences the electric field in the jet. A positively charged insoluble surfactant is present at the interface, and its evolution, as well as the resulting value of the local surface tension coefficient, is coupled with the voltage potential at the interface. The resulting coupled nonlinear systems are derived and analytical progress is made by carrying out a nonlinear slender jet approximation. The reduced model is described by a number of hydrodynamic, electrical, and electrokinetic parameters, and an extensive computational study is undertaken to elucidate the dynamics along with allied linear properties. It is established that the jet ruptures in finite time provided the outer electrode is sufficiently far away, and numerous examples are given where the dimensionless parameters can be used to control the size of the satellite drops that form beyond the topological transition, as well as the time to break up. It is also shown that pinching solutions follow the self-similar dynamics of clean viscous jets at times close to the breakup time. Finally, a further asymptotic theory is developed for large Debye layers to produce an additional model that incorporates the effects of surface charge diffusion. Numerical solutions establish that the presence of electrostatic and electrokinetic effects increases the sizes of satellites but have a rather weak influence on the time to rupture.

Conroy, D. T.; Matar, O. K.; Craster, R. V.; Papageorgiou, D. T.

2011-02-01

126

Effect of gas mass flux on cryogenic liquid jet breakup  

NASA Technical Reports Server (NTRS)

A scattered-light scanning instrument developed at NASA Lewis Research Center was used to measure the characteristic drop size of clouds of liquid nitrogen droplets. The instrument was calibrated with suspensions of monosized polystyrene spheres. In this investigation of the mechanism of liquid nitrogen jet disintegration in a high-velocity gas flow, the Sauter mean diameter, D32, was found to vary inversely with the nitrogen gas mass flux raised to the power 1.33. Values of D32 varied from 5 to 25 microns and the mass flux exponent of 1.33 agrees well with theory for liquid jet breakup in high-velocity gas flows. The loss of very small droplets due to the high vaporization rate of liquid nitrogen was avoided by sampling the spray very close to the atomizer, i.e., 1.3 cm downstream of the nozzle orifice. The presence of high velocity and thermal gradients in the gas phase also made sampling of the particles difficult. As a result, it was necessary to correct the measurements for background noise produced by both highly turbulent gas flows and thermally induced density gradients in the gas phase.

Ingebo, R. D.

1992-01-01

127

Analytical description of the breakup of liquid jets in air  

NASA Technical Reports Server (NTRS)

A viscous or inviscid cylindrical jet with surface tension in a vacuum tends to pinch due to the mechanism of capillary instability. Similarity solutions are constructed which describe this phenomenon as a critical time is encountered, for two physically distinct cases: inviscid jets governed by the Euler equations and highly viscous jets governed by the Stokes equations. In both cases the only assumption imposed is that at the time of pinching the jet shape has a radial length scale which is smaller than the axial length scale. For the inviscid case, we show that our solution corresponds exactly to one member of the one-parameter family of solutions obtained from slender jet theories and the shape of the jet is locally concave at breakup. For highly viscous jets our theory predicts local shapes which are monotonic increasing or decreasing indicating the formation of a mother drop connected to the jet by a thin fluid tube. This qualitative behavior is in complete agreement with both direct numerical simulations and experimental observations.

Papageorgiou, Demetrios T.

1993-01-01

128

Vibration-Induced Gas-Liquid Interface Breakup  

NASA Astrophysics Data System (ADS)

Gas-liquid interfaces can be forced to break up when subjected to vibrations within critical ranges of frequency and amplitude. This breakup mechanism was examined experimentally using deep layers of silicone oils over a range of viscosity and sinusoidal, primarily axial vibration conditions that can produce dramatic disturbances at the gas-liquid free surface. Although small-amplitude vibrations produce standing Faraday waves, large-amplitude vibrations produce liquid jets into the gas, droplets pinching off from the jets, gas cavities in the liquid from droplet impact, and bubble transport below the interface. Experiments used several different silicone oils over a range of pressures and vibration conditions. Computational simulations exhibiting similar behavior will be included in the presentation. Applications include liquid fuel rockets, inertial sensing devices, moving vehicles, mixing processes, and acoustic excitation. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

O'Hern, Timothy; Torczynski, John; Romero, Ed; Shelden, Bion

2010-11-01

129

Benchmark calculation for proton-deuteron elastic scattering observables including Coulomb  

E-print Network

Two independent calculations of proton-deuteron elastic scattering observables including Coulomb repulsion between the two protons are compared in the proton lab energy region between 3 MeV and 65 MeV. The hadron dynamics is based on the purely nucleonic charge-dependent AV18 potential. Calculations are done both in coordinate space and momentum space. The coordinate-space calculations are based on a variational solution of the three-body Schr\\"odinger equation using a correlated hyperspherical expansion for the wave function. The momentum-space calculations proceed via the solution of the Alt-Grassberger-Sandhas equation using the screened Coulomb potential and the renormalization approach. Both methods agree within 1% on all observables, showing the reliability of both numerical techniques in that energy domain. At energies below three-body breakup threshold the coordinate-space method remains favored whereas at energies higher than 65 MeV the momentum-space approach seems to be more efficient.

Deltuva, A; Kievsky, A; Rosati, S; Sauer, P U; Viviani, M

2005-01-01

130

Effects of large mass transfer and statistical decay on ternary breakup in the reaction U238+Au197 at 15A MeV  

NASA Astrophysics Data System (ADS)

The ternary breakup mechanism of U238+Au197 at 15A MeV has been investigated by a hybrid model that combines the improved quantum molecular dynamics (ImQMD) model together with a statistical code gemini++. The results are in good agreement with the experimental data and indicate that in peripheral reactions, ternary breakup in this reaction results from quasi-U statistical fission while for central and semicentral collisions it can be understood by a two-step mechanism: deep-inelastic collision (DIC) followed by a sequential binary breakup of one of the DIC products. In the process of DIC, there is a large mass transfer from Au to U to form transuranium. Due to the low fission barrier, such transuranium nuclei will decay into stable light nuclei through various fission modes. An event-by-event analysis shows that the second breakup mainly occurs in the deexcitation process and most of the ternary breakup events are from semicentral and peripheral collisions that correspond to deep inelastic and quasi-elastic reactions, respectively.

Jiang, Xiang; Yan, Shiwei

2014-08-01

131

Searching for Quarks in the Deuteron  

SciTech Connect

The deuteron has been studied in numerous elastic scattering and phatodisintegration experiments over a wide range of momentum transfers. A primary motivation is investigating the validity of theories based an hadronic vs. quark degrees of freedom. It is often thought that hadronic approaches will break dawn at large momentum transfers, and it will be necessary to use quark degrees of freedom. I will very briefly review the status of our understanding of the underlying theoretical issues, the world data sets for elastic scattering and photodisintegration, and the ability of hadronic and quark based theories to explain the data. Hadronic theories appear to provide good explanations for elastic scattering, but photodisintegration is very difficult to understand.

Ron Gilman

2002-06-01

132

Novel Physics with Tensor Polarized Deuteron Targets  

SciTech Connect

Development of solid spin-1 polarized targets will open the study of tensor structure functions to precise measurement, and holds the promise to enable a new generation of polarized scattering experiments. In this talk we will discuss a measurement of the leading twist tensor structure function b1, along with prospects for future experiments with a solid tensor polarized target. The recently approved JLab experiment E12-13-011 will measure the lead- ing twist tensor structure function b1, which provides a unique tool to study partonic effects, while also being sensitive to coherent nuclear properties in the simplest nuclear system. At low x, shadowing effects are expected to dominate b1, while at larger values, b1 provides a clean probe of exotic QCD effects, such as hidden color due to 6-quark configuration. Since the deuteron wave function is relatively well known, any non-standard effects are expected to be readily observable. All available models predict a small or vanishing value of b1 at moderate x. However, the first pioneer measurement of b1 at HERMES revealed a crossover to an anomalously large negative value in the region 0.2 < x < 0.5, albeit with relatively large experimental uncertainty. E12-13-011 will perform an inclusive measurement of the deuteron tensor asymmetry in the region 0.16 < x < 0.49, for 0.8 < Q2 < 5.0 GeV2. The UVa solid polarized ND3 target will be used, along with the Hall C spectrometers, and an unpolarized 115 nA beam. This measurement will provide access to the tensor quark polarization, and allow a test of the Close-Kumano sum rule, which vanishes in the absence of tensor polarization in the quark sea. Until now, tensor structure has been largely unexplored, so the study of these quantities holds the potential of initiating a new field of spin physics at Jefferson Lab.

Slifer, Karl J. [UNH; Long, Elena A. [UNH

2013-09-01

133

Surface-integral formalism of deuteron stripping  

E-print Network

The purpose of this paper is to develop an alternative theory of deuteron stripping to resonance states based on the surface integral formalism of Kadyrov et al. [Ann. Phys. 324, 1516 (2009)] and continuum-discretized coupled channels (CDCC). First we demonstrate how the surface integral formalism works in the three-body model and then we consider a more realistic problem in which a composite structure of target nuclei is taken via optical potentials. We explore different choices of channel wave functions and transition operators and show that a conventional CDCC volume matrix element can be written in terms of a surface-integral matrix element, which is peripheral, and an auxiliary matrix element, which determines the contribution of the nuclear interior over the variable $r_{nA}$. This auxiliary matrix element appears due to the inconsistency in treating of the $n-A$ potential: this potential should be real in the final state to support bound states or resonance scattering and complex in the initial state to describe $n-A$ scattering. Our main result is formulation of the theory of the stripping to resonance states using the prior form of the surface integral formalism and CDCC method. It is demonstrated that the conventional CDCC volume matrix element coincides with the surface matrix element, which converges for the stripping to the resonance state. Also the surface representation (over the variable $r_{nA}$ of the stripping matrix element enhances the peripheral part of the amplitude although the internal contribution doesn't disappear and increases with increase of the deuteron energy. We present calculations corroborating our findings for both stripping to the bound state and the resonance.

A. M. Mukhamedzhanov; D. Y. Pang; C. A. Bertulani; A. S. Kadyrov

2014-08-24

134

Solving the three-body Coulomb breakup problem using exterior complex scaling  

SciTech Connect

Electron-impact ionization of the hydrogen atom is the prototypical three-body Coulomb breakup problem in quantum mechanics. The combination of subtle correlation effects and the difficult boundary conditions required to describe two electrons in the continuum have made this one of the outstanding challenges of atomic physics. A complete solution of this problem in the form of a ''reduction to computation'' of all aspects of the physics is given by the application of exterior complex scaling, a modern variant of the mathematical tool of analytic continuation of the electronic coordinates into the complex plane that was used historically to establish the formal analytic properties of the scattering matrix. This review first discusses the essential difficulties of the three-body Coulomb breakup problem in quantum mechanics. It then describes the formal basis of exterior complex scaling of electronic coordinates as well as the details of its numerical implementation using a variety of methods including finite difference, finite elements, discrete variable representations, and B-splines. Given these numerical implementations of exterior complex scaling, the scattering wave function can be generated with arbitrary accuracy on any finite volume in the space of electronic coordinates, but there remains the fundamental problem of extracting the breakup amplitudes from it. Methods are described for evaluating these amplitudes. The question of the volume-dependent overall phase that appears in the formal theory of ionization is resolved. A summary is presented of accurate results that have been obtained for the case of electron-impact ionization of hydrogen as well as a discussion of applications to the double photoionization of helium.

McCurdy, C.W.; Baertschy, M.; Rescigno, T.N.

2004-05-17

135

A Determination of the Mass of the Deuteron  

NASA Astrophysics Data System (ADS)

We have measured the atomic mass of the deuteron relative to the calibration 12C6+ and 12C4+ ions and arrived at a value of 2 014 101 778 052 (40) pu for the mass of deuterium and 2 013 553 212 744 (40) pu for the mass of the deuteron. The spectroscopy was performed in the new University of Washington Penning Trap Mass Spectrometer (UW-PTMS). The measurement was made by using the experiment to make a very accurate determination of the cyclotron frequency of a deuteron isolated in a Penning trap, followed by the cyclotron frequency of a carbon calibration ion, isolated at the same place in that same trap. The ratio of the cyclotron frequencies is inversely proportional to the ratio of the two ion's mass-to-charge ratio after systematic corrections are made. The deuteron mass along with the proton mass, which also has its best measurement at the UW-PTMS, can be used with the deuteron binding energy[20] to refine the neutron mass to mn= 1 008 664 916 018 (435) pu. In addition to discussing the physics of our penning trap spectrometer and the systematic corrections necessary to obtain a mass ratio, improvements to the spectrometer will be described that were used in the deuteron measurement as well as improvements that were made later for future measurements.

Zafonte, Steven Leo

136

Termination of spiral wave breakup in a Fitzhugh-Nagumo model via short and long duration stimuli  

NASA Astrophysics Data System (ADS)

Rotating spiral waves have been observed in a variety of nonlinear biological and physical systems. Spiral waves are found in excitable and oscillatory systems and can be stationary, meander, or even degenerate into multiple unstable rotating waves (a process called "spiral wave breakup"). In the heart, spiral wave breakup is thought to be the underlying mechanism of cardiac fibrillation. The spatiotemporal complexity of multiple unstable spiral waves is difficult to control or terminate. Here, the mechanisms of the termination of spiral wave breakup in response to global stimulation are investigated. A modified Fitzhugh-Nagumo model was used to represent cellular kinetics to study the role of the fast (activation) and slow (recovery) variables. This simplified model allows a theoretical analysis of the termination of spiral wave breakup via both short and long duration pulses. Simulations were carried out in both two-dimensional sheets and in a three-dimensional geometry of the heart ventricles. The short duration pulses affected only the fast variable and acted to reset wave propagation. Monophasic pulses excited tissue ahead of the wave front thus reducing the amount of excitable tissue. Biphasic shocks did the same, but they also acted to generate new wave fronts from the pre-existing wave tails by making some active regions excitable. Thus, if the short duration stimuli were strong enough, they acted to fill in excitable tissue via propagating wave fronts and terminated all activity. The long duration wave forms were selected such that they had a frequency spectrum similar to that of the pseudoelectrocardiograms recorded during fibrillation. These long duration wave forms affected both the recovery and activation variables, and the mechanism of unstable multiple spiral wave termination was different compared to the short duration wave forms. If the long duration stimuli were strong enough, they acted to alter the "state" (i.e., combination of fast and slow variables) of the tissue throughout 1.5 cycles, thus "conditioning" the tissue such that by the end of the stimuli almost no excitable tissue remained. The peak current, total energy, and average power of stimuli required to terminate spiral wave breakup were less for the long duration wave forms compared to the short duration wave forms. In addition, closed loop feedback via stimulation with a wave form that was the difference of the pseudoelectrocardiogram and a strongly periodic chaotic signal was successful at terminating spiral wave breakup. These results suggest that it may be possible to improve cardiac defibrillation efficacy by using long duration wave forms to affect recovery variables in the heart as opposed to the traditional brief duration wave forms that act only on the fast variables.

Gray, Richard A.

2002-09-01

137

Self-similar Breakup of Near-inviscid Fluids  

E-print Network

of images for front- pinching (region A) are shown in Figure 2 and examples of the breakup within the filament(region C) are pre- sented in Fig. 3. The shadowgraph scheme consisted of a 150 W fibre optics lamp (MFO-90, Microtec), an optical diffuser (1... observed, the flow is Qwater4 = 0.750 ml/s. The asymptotic analysis shows that at the point of breakup (t=0 µs) ? = 19.2± 0.9?. coupled to a microscope lens (12× ultra zoom, Navitar). Although this optical system is known to produce pin- cushion distortion...

Castrejon-Pita, J.R.; Castrejon-Pita, A.A.; Hinch, E.J.; Lister, J.R.; Hutchings, I.M.

2012-01-01

138

On the breakup of tectonic plates by polar wandering  

NASA Technical Reports Server (NTRS)

The equations for the stresses in a homogeneous shell of uniform thickness caused by a shift of the axis of rotation are derived. The magnitude of these stresses reaches a maximum value of the order of 10 to the 9th power dyn/sq cm, which is sufficient for explaining a tectonic breakup. In order to deduce the fracture pattern according to which the breakup of tectonic plates can be expected the theory of plastic deformation of shells is applied. The analysis of this pattern gives an explanation of the existing boundary systems of the major tectonic plates as described by Morgan (1968), LePichon (1968) and Isacks et al. (1968).

Liu, H.-S.

1974-01-01

139

Uncertainty assessment for the breakup of satellites due to hypervelocity impacts  

Microsoft Academic Search

The breakup of a spacecraft or its components due to hypervelocity impact is a very chaotic event. Given the best of conditions, no two breakups will be exactly the same. This uncertainty in the physical processes spills over into attempts to develop computer models to do breakup analysis and future debris environment forecasting. Because of this uncertainty, even the \\

David B. Spencer; Keith A. Akins

2001-01-01

140

Preventing alternans-induced spiral wave breakup in cardiac tissue: An ion-channel-based approach  

E-print Network

Preventing alternans-induced spiral wave breakup in cardiac tissue: An ion-channel-based approach D growing alternans modes over the entire tissue, thus inhibiting spiral wave breakup. DOI: 10.1103/Phys (Received 12 March 2004; published 3 December 2004) The detailed processes involved in spiral wave breakup

Otani, Niels F.

141

The reaction proton deuteron yields triton pion at 470 and 590 MeV  

NASA Technical Reports Server (NTRS)

The preliminary results from a study of the deuteron (proton, positive pion)triton reaction are reported. The differential cross section for this reaction was measured for a number of center of mass angles from 37 deg to 160 deg at incident proton energies of 470 and 590 MeV. The cross sections measured at 590 MeV agree with predictions made considering a two-nucleon process. The 470 MeV data shows a peak in the backward direction which is not predicted by this mechanism.

Dollhopf, W.; Lunke, C.; Perdrisat, C. F.; Roberts, W. K.; Kitching, P.; Olsen, W. C.; Priest, J. R.

1973-01-01

142

A re-evaluation of metal diapir breakup and equilibration in terrestrial magma oceans  

NASA Astrophysics Data System (ADS)

Due to mechanisms such as impact heating, early atmospheric thermal blanketing, and radioactive heating, the presence of at least one global magma ocean stage in the early histories of terrestrial planets seems unavoidable. In such a context, a key question to constrain the early thermo-chemical evolution of the Earth is how much iron diapirs provided by differentiated impactors emulsified during their sinking towards the bottom of an early magma ocean. In the past years, several workers have focused on this question, using however various approaches and making different assumptions. While most studies favor rapid breakup and equilibration of iron bodies during their sinking through the magma ocean, recent work suggests that iron bodies of size comparable or greater than a few tens of kilometers may preserve most of their initial volume as they reach the bottom of a magma ocean, therefore leading to metal-silicate disequilibrium. To clarify the discrepancies and the differences among studies I have conducted a series of numerical simulations and theoretical calculations to derive the conditions and the timing for the breakup of metal diapirs of any size, sinking through a silicate magma ocean, with a large range of plausible viscosity values. The obtained breakup criterion is used to derive stable diapir sizes and their ability to equilibrate with the surrounding silicates. I show that for plausible magma ocean viscosities, diapirs with initial radii smaller than the thickness of a magma ocean rapidly break up into stable diapir sizes smaller than 0.2 m, at which metal-silicate equilibration is rapidly achieved.

Samuel, Henri

2012-01-01

143

The Soviet Breakup and U.S. Foreign Policy.  

ERIC Educational Resources Information Center

This issue of a quarterly publication on world affairs explores the historical significance of the disintegration of the Soviet Union and the implication for U.S. foreign policy. With the breakup of the USSR in 1990-91, Russia for the first time this century does not have control over the non-Russian nations of its former empire in Central Asia,…

Lynch, Allen

1991-01-01

144

NASA's new breakup model of evolve 4.0  

Microsoft Academic Search

Analyses of the fragmentation (due to explosions and collisions) of spacecraft and rocket bodies in low Earth orbit (LEO) have been performed this year at NASA\\/JSC. The overall goals of this study have been to achieve a better understanding of the results of fragmentations on the orbital debris environment and then to implement this understanding into the breakup model of

N. L. Johnson; P. H. Krisko; J.-C. Liou; P. D. Anz-Meador

2001-01-01

145

Color Breakup In Sequentially-Scanned LC Displays  

NASA Technical Reports Server (NTRS)

In sequentially-scanned liquid-crystal displays the chromatic components of color pixels are distributed in time. For such displays eye, head, display, and image-object movements can cause the individual color elements to be visible. We analyze conditions (scan designs, types of eye movement) likely to produce color breakup.

Arend, L.; Lubin, J.; Gille, J.; Larimer, J.; Statler, Irving C. (Technical Monitor)

1994-01-01

146

Ablation and Breakup of Large Meteoroids during Atmospheric Entry  

Microsoft Academic Search

An ablation model is described that can be used to estimate the effect on a large meteoroid of passage through a planetary atmosphere. The effect on ablation and deceleration of breakup due to aerodynamic pressure is investigated. Results from arc-jet wind-tunnel tests and strength measurements of meteorite samples have been used to help determine the material properties needed in the

Barrett Baldwin; Yvonne Sheaffer

1971-01-01

147

Nuclear induced breakup of halo nuclei H. Esbensen  

E-print Network

energies. The description of breakup reactions at low beam energies is much more difficult because one, which is the conventional method used to describe low-energy, heavy-ion reactions of ordinary nuclei treatment is much larger than the exact result. This trend is also indicated at low energy by comparing

Bertsch George F.

148

On causal links between flood basalts and continental breakup  

Microsoft Academic Search

Temporal coincidence between continental flood basalts and breakup has been noted for almost three decades. Eight major continental flood basalts have been produced over the last 300 Ma. The most recent, the Ethiopian traps, erupted in about 1 Myr at 30 Ma. Rifting in the Red Sea and Gulf of Aden, and possibly East African rift started at about the

V. Courtillot; C. Jaupart; I. Manighetti; P. Tapponnier; J. Besse

1999-01-01

149

Current reduction in a pseudo-breakup event: THEMIS observations  

NASA Astrophysics Data System (ADS)

events are thought to be generated by the same physical processes as substorms. This paper reports on the cross-tail current reduction in an isolated pseudo-breakup observed by three of the THEMIS probes (THEMIS A (THA), THEMIS D (THD), and THEMIS E (THE)) on 22 March 2010. During this pseudo-breakup, several localized auroral intensifications were seen by ground-based observatories. Using the unique spatial configuration of the three THEMIS probes, we have estimated the inertial and diamagnetic currents in the near-Earth plasma sheet associated with flow braking and diversion. We found the diamagnetic current to be the major contributor to the current reduction in this pseudo-breakup event. During flow braking, the plasma pressure was reinforced, and a weak electrojet and an auroral intensification appeared. After flow braking/diversion, the electrojet was enhanced, and a new auroral intensification was seen. The peak current intensity of the electrojet estimated from ground-based magnetometers, ~0.7 × 105 A, was about 1 order of magnitude lower than that in a typical substorm. We suggest that this pseudo-breakup event involved two dynamical processes: a current-reduction associated with plasma compression ahead of the earthward flow and a current-disruption related to the flow braking/diversion. Both processes are closely connected to the fundamental interaction between fast flows, the near-Earth ambient plasma, and the magnetic field.

Yao, Z. H.; Pu, Z. Y.; Owen, C. J.; Fu, S. Y.; Chu, X. N.; Liu, J.; Angelopoulos, V.; Rae, I. J.; Yue, C.; Zhou, X.-Z.; Zong, Q.-G.; Cao, X.; Shi, Q. Q.; Forsyth, C.; Du, A. M.

2014-10-01

150

Spray formation: 3D liquid breakup due to surface tension  

Microsoft Academic Search

The objective of the work was the investigation of fluid dynamic and surface tension instabilities that effect the breakup of fuel jets in the atomization process. Computational and analytical methods were used. Initial work involved the evaluation of numerical methods for flows with density discontinuities. It was discovered that many commonly used methods are poorly suited to predicting two phase

Robert E. Childs; Nagi N. Mansour

1987-01-01

151

Breakup of New Orleans Households after Hurricane Katrina  

ERIC Educational Resources Information Center

Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household breakup resulting from Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads…

Rendall, Michael S.

2011-01-01

152

Chain reaction led to breakup of Larsen B Ice Shelf  

NASA Astrophysics Data System (ADS)

In 2002, Antarctica's Larsen B Ice Shelf disintegrated over the course of just a few months. The shelf, which covered more than 3000 square kilometers of ice, had been stable for thousands of years before it broke up, and the processes involved in the sudden breakup were not well understood.

Balcerak, Ernie

2014-02-01

153

High Energy Two-Body Deuteron Photodisintegration  

SciTech Connect

The differential cross section for two­body deuteron photodisintegration was measured at photon energies between 0.8 and 4.0 GeV and center­of­mass angles theta_cm =37deg, 53deg, 70deg, and 90deg as part of CEBAF experiment E89­012. Constituent counting rules predict a scaling of this cross section at asymptotic energies. In previous experiments this scaling has surprisingly been observed at energies between 1.4 and 2.8 GeV at 90deg. The results from this experiment are in reasonable agreement with previous measurements at lower energies. The data at 70deg and 90deg show a constituent counting rule behavior up to 4.0 GeV photon energy. The 37deg and 53deg data do not agree with the constituent counting rule prediction. The new data are compared with a variety of theoretical models inspired by quantum chromodynamics (QCD) and traditional hadronic nuclear physics.

Bart Terburg

1999-07-31

154

PLATYPUS: a code for fusion and breakup in reactions induced by weakly-bound nuclei within a classical trajectory model with stochastic breakup  

E-print Network

A self-contained Fortran-90 program based on a classical trajectory model with stochastic breakup is presented, which should be a powerful tool for quantifying complete and incomplete fusion, and breakup in reactions induced by weakly-bound two-body projectiles near the Coulomb barrier. The code calculates complete and incomplete fusion cross sections and their angular momentum distribution, as well as breakup observables (angle, kinetic energy and relative energy distributions).

Alexis Diaz-Torres

2011-01-18

155

PLATYPUS: a code for fusion and breakup in reactions induced by weakly-bound nuclei within a classical trajectory model with stochastic breakup  

E-print Network

A self-contained Fortran-90 program based on a classical trajectory model with stochastic breakup is presented, which should be a powerful tool for quantifying complete and incomplete fusion, and breakup in reactions induced by weakly-bound two-body projectiles near the Coulomb barrier. The code calculates complete and incomplete fusion cross sections and their angular momentum distribution, as well as breakup observables (angle, kinetic energy and relative energy distributions).

Diaz-Torres, Alexis

2007-01-01

156

Application of deuteron-deuteron (D-D) fusion neutrons to 40Ar/39Ar geochronology.  

PubMed

Neutron irradiation of samples for 40Ar/39Ar dating in a 235U fission reactor requires error-producing corrections for the argon isotopes created from Ca, K, and, to a lesser extent, Cl. The fission spectrum includes neutrons with energies above 2-3 MeV, which are not optimal for the 39K(n,p)39Ar reaction. These higher-energy neutrons are responsible for the largest recoil displacements, which may introduce age artifacts in the case of fine-grained samples. Both interference corrections and recoil displacements would be significantly reduced by irradiation with 2.45 MeV neutrons, which are produced by the deuteron-deuteron (D-D) fusion reaction 2H(d,n)3He. A new generation of D-D reactors should yield sufficiently high neutron fluxes (>10(12) n cm(-2)s(-1)) to be useful for 40Ar/39Ar dating. Modeling indicates that irradiation with D-D neutrons would result in scientific benefits of improved accuracy and broader applicability to fine-grained materials. In addition, radiological safety would be improved, while both maintenance and operational costs would be reduced. Thus, development of high-flux D-D fusion reactors is a worthy goal for 40Ar/39Ar geochronology. PMID:15498681

Renne, Paul R; Knight, Kim B; Nomade, Sébastien; Leung, Ka-Ngo; Lou, Tak-Pui

2005-01-01

157

Bubble mechanisms and characteristics at pore scale in a packed-bed reactor  

Microsoft Academic Search

An image processing technique was used to study dominant bubble mechanisms in a two-dimensional packed-bed at pore level under the bubbly flow regime. Bubble breakup and coalescence were identified as dominant mechanisms using a large number of image samples. Two types of coalescence mechanisms were identified that occur due to compression and deceleration associated with the bubbles and three breakup

Daeseong Jo; Shripad T. Revankar

2009-01-01

158

Quasielastic electron-deuteron scattering in the weak binding approximation  

E-print Network

We perform a global analysis of all available electron-deuteron quasielastic scattering data using Q^2-dependent smearing functions that describe inclusive inelastic e-d scattering within the weak binding approximation. We study the dependence of the cross sections on the deuteron wave function and the off-shell extrapolation of the elastic electron-nucleon cross sections, which show particular sensitivity at x >> 1. The excellent overall agreement with data over a large range of Q^2 and x suggests a limited need for effects beyond the impulse approximation, with the possible exception of the very high-x or very low-Q^2 regions, where short-distance effects or scattering from non-nucleonic constituents in the deuteron become more relevant.

J. J. Ethier; N. Doshi; S. Malace; W. Melnitchouk

2014-02-17

159

Exclusive measurement of coherent eta photoproduction from the deuteron  

E-print Network

Coherent photoproduction of eta mesons from the deuteron has been measured from threshold up to incident photon energies of 750 MeV using the photon spectrometer TAPS at the tagged photon facility at the Mainz microtron MAMI. For the first time, differential coherent cross sections have been deduced from the coincident detection of the eta meson and the recoil deuteron. A missing energy analysis was used for the suppression of background events so that a very clean identification of coherent eta-photoproduction was achieved. The resulting cross sections agree with previous experimental results except for angles around 90 deg in the photon-deuteron cm-system where they are smaller. They are compared to various model calculations.

J. Weiss; P. Achenbach; J. Ahrens; J. R. M. Annand; R. Beck; V. Hejny; J. D. Kellie; V. Kleber; M. Kotulla; B. Krusche; V. Kuhr; R. Leukel; V. Metag; V. M. Olmos de Leon; F. Rambo; A. Schmidt; U. Siodlaczek; H. Stroeher; F. Wissmann; M. Wolf

2003-04-02

160

Exclusive rho^0 muoproduction on transversely polarised protons and deuterons  

E-print Network

The transverse target spin azimuthal asymmetry A_UT in hard exclusive production of rho^0 mesons was measured at COMPASS by scattering 160 GeV/c muons off transversely polarised protons and deuterons. The measured asymmetry is sensitive to the nucleon helicity-flip generalised parton distributions E^q, which are related to the orbital angular momentum of quarks in the nucleon. The Q^2, x_B and p_t^2 dependence of A_UT is presented in a wide kinematic range. Results for deuterons are obtained for the first time. The measured asymmetry is small in the whole kinematic range for both protons and deuterons, which is consistent with the theoretical interpretation that contributions from GPDs E^u and E^d approximately cancel.

C. Adolph; M. G. Alekseev; V. Yu. Alexakhin; Yu. Alexandrov; G. D. Alexeev; A. Amoroso; A. A. Antonov; A. Austregesilo; B. Bade?ek; F. Balestra; J. Barth; G. Baum; Y. Bedfer; J. Bernhard; R. Bertini; M. Bettinelli; K. Bicker; J. Bieling; R. Birsa; J. Bisplinghoff; P. Bordalo; F. Bradamante; C. Braun; A. Bravar; A. Bressan; M. Büchele; E. Burtin; L. Capozza; M. Chiosso; S. U. Chung; A. Cicuttin; M. L. Crespo; S. Dalla Torre; S. Das; S. S. Dasgupta; S. Dasgupta; O. Yu. Denisov; L. Dhara; S. V. Donskov; N. Doshita; V. Duic; W. Dünnweber; M. Dziewiecki; A. Efremov; C. Elia; P. D. Eversheim; W. Eyrich; M. Faessler; A. Ferrero; A. Filin; M. Finger; M. Finger Jr; H. Fischer; C. Franco; N. du Fresne von Hohenesche; J. M. Friedrich; V. Frolov; R. Garfagnini; F. Gautheron; O. P. Gavrichtchouk; S. Gerassimov; R. Geyer; M. Giorgi; I. Gnesi; B. Gobbo; S. Goertz; S. Grabmüller; A. Grasso; B. Grube; R. Gushterski; A. Guskov; T. Guthörl; F. Haas; D. von Harrach; F. H. Heinsius; F. Herrmann; C. Heß; F. Hinterberger; N. Horikawa; Ch. Höppner; N. d'Hose; S. Ishimoto; O. Ivanov; Yu. Ivanshin; T. Iwata; R. Jahn; V. Jary; P. Jasinski; G. Jegou; R. Joosten; E. Kabuß; D. Kang; B. Ketzer; G. V. Khaustov; Yu. A. Khokhlov; Yu. Kisselev; F. Klein; K. Klimaszewski; S. Koblitz; J. H. Koivuniemi; V. N. Kolosov; K. Kondo; K. Königsmann; I. Konorov; V. F. Konstantinov; A. Korzenev; A. M. Kotzinian; O. Kouznetsov; M. Krämer; Z. V. Kroumchtein; F. Kunne; K. Kurek; L. Lauser; A. A. Lednev; A. Lehmann; S. Levorato; J. Lichtenstadt; T. Liska; A. Maggiora; A. Magnon; N. Makke; G. K. Mallot; A. Mann; C. Marchand; A. Martin; J. Marzec; T. Matsuda; G. Meshcheryakov; W. Meyer; T. Michigami; Yu. V. Mikhailov; M. A. Moinester; A. Morreale; A. Mutter; A. Nagaytsev; T. Nagel; T. Negrini; F. Nerling; S. Neubert; D. Neyret; V. I. Nikolaenko; W. -D. Nowak; A. S. Nunes; A. G. Olshevsky; M. Ostrick; A. Padee; R. Panknin; D. Panzieri; B. Parsamyan; S. Paul; E. Perevalova; G. Pesaro; D. V. Peshekhonov; G. Piragino; S. Platchkov; J. Pochodzalla; J. Polak; V. A. Polyakov; J. Pretz; M. Quaresma; C. Quintans; J. -F. Rajotte; S. Ramos; V. Rapatsky; G. Reicherz; A. Richter; E. Rocco; E. Rondio; N. S. Rossiyskaya; D. I. Ryabchikov; V. D. Samoylenko; A. Sandacz; M. G. Sapozhnikov; S. Sarkar; I. A. Savin; G. Sbrizzai; P. Schiavon; C. Schill; T. Schlüter; K. Schmidt; L. Schmitt; K. Schönning; S. Schopferer; M. Schott; W. Schröder; O. Yu. Shevchenko; L. Silva; L. Sinha; A. N. Sissakian; M. Slunecka; G. I. Smirnov; S. Sosio; F. Sozzi; A. Srnka; L. Steiger; M. Stolarski; M. Sulc; R. Sulej; H. Suzuki; P. Sznajder; S. Takekawa; J. Ter Wolbeek; S. Tessaro; F. Tessarotto; L. G. Tkatchev; S. Uhl; I. Uman; M. Vandenbroucke; M. Virius; N. V. Vlassov; L. Wang; M. Wilfert; R. Windmolders; W. Wi?licki; H. Wollny; K. Zaremba; M. Zavertyaev; E. Zemlyanichkina; M. Ziembicki; N. Zhuravlev; A. Zvyagin

2012-09-17

161

Quasielastic electron-deuteron scattering in the weak binding approximation  

SciTech Connect

We perform a global analysis of all available electron-deuteron quasielastic scattering data using Q^2-dependent smearing functions that describe inclusive inelastic e-d scattering within the weak binding approximation. We study the dependence of the cross sections on the deuteron wave function and the off-shell extrapolation of the elastic electron-nucleon cross section, which show particular sensitivity at x >> 1. The excellent overall agreement with data over a large range of Q^2 and x suggest a limited need for effects beyond the impulse approximation, with the exception of the very high-x or very low-Q^2 regions, where short-distance effects in the deuteron become more relevant.

Ethier, Jacob J. [William and Mary College, JLAB; Doshi, Nidhi P. [Carnegie Mellon University; Malace, Simona P. [JLAB; Melnitchouk, Wally [JLAB

2014-06-01

162

Exotic break-up modes in heavy ion reactions at low energies  

E-print Network

New reaction mechanisms occurring in heavy ion collisions at low energy (10- 30 MeV/A) are investigated within the Stochastic Mean Field model. We concentrate on the analysis of ternary breakup events, of dynamical origin, occurring in semi-central reactions, where the formation of excited systems in various conditions of shape and angular momentum is observed. We show how this fragmentation mode, which can be considered as a precursor of the neck emission observed at higher beam energies, emerges from the combined action of surface (neck) instabilities and angular momentum effects. Interesting perspectives are opening towards the investigation of this mechanism in neutron-rich (or exotic) systems, with the possibility to access information on the low-density behavior of the nuclear symmetry energy.

C. Rizzo; M. Colonna; V. Baran; M. Di Toro

2014-07-03

163

Breakup of liquid jets from non-circular orifices  

NASA Astrophysics Data System (ADS)

The purpose of this investigation is to study the effect of the orifice geometry on liquid breakup. In order to develop a better understanding of the liquid jet breakup, investigations were carried out in two steps—study of low-pressure liquid jet breakup and high-pressure fuel atomization. This paper presents the experimental investigations conducted to study the flow behavior of low-pressure water jets emanating from orifices with non-circular geometries, including rectangular, square, and triangular shapes and draws a comparison with the flow behavior of circular jets. The orifices had approximately same cross-sectional areas and were machined by electro-discharge machining process in stainless steel discs. The liquid jets were discharged in the vertical direction in atmospheric air at room temperature and pressure conditions. The analysis was carried out for gage pressures varying from 0 to 1,000 psi (absolute pressures from 0.10 to 6.99 MPa). The flow behavior was analyzed using high-speed visualization techniques. To draw a comparison between flow behavior from circular and non-circular orifices, jet breakup length and width were measured. The flow characteristics were analyzed from different directions, including looking at the flow from the straight edges of the orifices as well as their sharp corners. The non-circular geometric jets demonstrated enhanced instability as compared to the circular jets. This has been attributed to the axis-switching phenomenon exhibited by them. As a result, the non-circular jets yielded shorter breakup lengths as compared to the circular jets. In order to demonstrate the presence of axis-switching phenomenon in square and triangular jets, the jet widths were plotted along the axial direction. This technique clearly demonstrated the axis switching occurring in square and triangular jets, which was not clearly visible unlike the case of rectangular jets. To conclude, non-circular geometry induces greater instabilities in the liquid jets, thereby leading to faster disintegration. Thus, non-circular orifice geometries can provide a cheaper solution of improving liquid breakup and thus may enhance fuel atomization as compared to the precise manufacturing techniques of drilling smaller orifices or using costly elevated fuel injection pressure systems.

Sharma, Priyesh; Fang, Tiegang

2014-02-01

164

Isoscalar Spin Strength in CARBON-12 and Calcium -40 Measured by Polarized Deuteron, Polarized Deuteron' Scattering  

NASA Astrophysics Data System (ADS)

The distribution of isoscalar spin strength in ^{12}C and ^ {40}Ca was measured with the inelastic scattering of 400 MeV polarized deuterons. Both nuclei were studied at laboratory angles from 3^ circ to 7^circ, and the isoscalar spin strength distributions were mapped out up to approximately 57 MeV in excitation energy for ^{12}C and 42 MeV in ^{40}Ca. Previously unknown concentrations of isoscalar spin strength were found in ^{40}Ca in the regions around 8 MeV and 15 MeV. New clusters of strength were also found in ^{12}C, near 21 and 30 MeV, as well as a possible new Delta T = 0, Delta S = 1 discrete state at 20.5 MeV. Very little collectivity was seen in either nucleus, which is consistent with theoretical and experimental predictions of a weakly repulsive residual interaction in this channel.

Johnson, Barry Newell

1993-01-01

165

Apparent temperature of fragments in the breakup of spectator residues  

SciTech Connect

Assuming the sequential decay of particle unstable primary fragments for light fragment production and the direct two body decay for heavy fragment production, we analyze the apparent temperature (the inverse logarithmic slope of kinetic energy distributions) of fragments in the breakup of spectator residues. Unlike other models it is independent of the projectile energy. Mass numbers obtained for the particle unstable primary fragments in the reactions of projectile proton and targets of Kr, Ag, and Xe are in the range 14-18.

Masuda, N.; Nitto, T.; Uchiyama, F.

1986-12-01

166

Radial electron-beam-breakup transit-time oscillator  

SciTech Connect

A new radially-driven electron-beam-breakup transit-time oscillator has been investigated analytically and through computer simulation as a compact low-impedance high-power microwave generator. In a 1MV, 50kA device 35cm in radius and 15cm long, with no external magnetic field, 5GW of extracted power and a growth rate of 0.26/ns have been observed. Theoretical maximum efficiencies are several times higher.

Mostrom, M.A. [Mission Research Corp., Albuquerque, NM (United States); Kwan, T.J.T. [Los Alamos National Lab., NM (United States)

1995-01-01

167

Compound orbits break-up in constituents: an algorithm  

E-print Network

In this paper decomposition of periodic orbits in bifurcation diagrams are derived in unidimensional dynamics system $x_{n+1}=f(x_{n};r)$, being $f$ an unimodal function. We proof a theorem which states the necessary and sufficient conditions for the break-up of compound orbits in their simpler constituents. A corollary to this theorem provides an algorithm for the computation of those orbits. This process closes the theoretical framework initiated in (Physica D, 239:1135--1146, 2010).

Jesús San Martín; A. González Gómez; Ma José Moscoso; Daniel Rodríguez-Pérez

2014-02-24

168

Breakup and early seafloor spreading between India and Antarctica  

Microsoft Academic Search

We present a tectonic interpretation of the breakup and early seafloor spreading between India and Antarctica based on improved coverage of potential field and seismic data off the east Antarctic margin between the Gunnerus Ridge and the Bruce Rise. We have identified a series of ENE trending Mesozoic magnetic anomalies from chron M9o (~130.2 Ma) to M2o (~124.1 Ma) in

Carmen Gaina; R. Dietmar Müller; Belinda Brown; Takemi Ishihara; Sergey Ivanov

2007-01-01

169

Collision and Breakup of Water Drops at Terminal Velocity  

Microsoft Academic Search

The collision and subsequent breakup of water drops moving essentially vertically and at terminal velocity has been studied for five drop pairs: the diameters Ds of the large drops were 4.8, 3.6 and 3.0 mm; the diameters D3 of the small drops were 1.8 mm and 1.0 mm. 712 collisions were obtained in 25,000 individually recorded attempts. Three distinct types

J. D. McTaggart-Cowan; Roland List

1975-01-01

170

Beam-breakup calculations for the DARHT accelerator  

Microsoft Academic Search

An induction line that will accelerate a 4-MeV, 3-kA beam of electrons to 16- to 20-MeV in 64 gaps is modeled. To suppress beam-breakup (BBU) instabilities induced by excitation of RF deflecting modes, the growth factor ? must be kept sufficiently small (e.g. <3). On prototype DARHT cavities, RF measurements have shown that the normally degenerate TM modes are split

Paul Allison; M. J. Burns; George J. Caporaso; A. G. Cole

1991-01-01

171

JET BREAKUP AND SPRAY FORMATION IN A DIESEL ENGINE.  

SciTech Connect

The breakup of injected fuel into spray is of key interest to the design of a fuel efficient, nonpolluting diesel engine. We report preliminary progress on the numerical simulation of diesel fuel injection spray with the front tracking code FronTier. Our simulation design is set to match experiments at ANL, and our present agreement is semi-quantitative. Future efforts will include mesh refinement studies, which will better model the turbulent flow.

GLIMM,J.; LI,X.; KIM,M.N.; OH,W.; MARCHESE,A.; SAMULYAK,R.; TZANOS,C.

2003-06-17

172

Breakup of small aggregates driven by turbulent hydrodynamic stress  

E-print Network

Breakup of small solid aggregates in homogeneous and isotropic turbulence is studied theoretically and by using Direct Numerical Simulations at high Reynolds number, Re_{\\lambda} \\simeq 400. We show that turbulent fluctuations of the hydrodynamic stress along the aggregate trajectory play a key role in determining the aggregate mass distribution function. Differences between turbulent and laminar flows are discussed. A novel definition of the fragmentation rate is proposed in terms of the typical frequency at which the hydrodynamic stress becomes sufficiently high to cause breakup along each Lagrangian path. We also define an Eulerian proxy of the real fragmentation rate, based on the joint statistics of the stress and its time derivative, which should be easier to measure in any experimental set-up. Both our Eulerian and Lagrangian formulations define a clear procedure for the computation of the mass distribution function due to fragmentation. Contrary, previous estimates based only on single point statistics of the hydrodynamic stress exhibit some deficiencies. These are discussed by investigating the evolution of an ensemble of aggregates undergoing breakup and aggregation.

Matthaus U. Babler; Luca Biferale; Alessandra S. Lanotte

2012-01-24

173

NAVSPASUR orbital processing for satellite break-up events  

NASA Technical Reports Server (NTRS)

Satellite breakups via explosion or collision can instantly increase the trackable orbiting population by up to several hundred objects, temporarily perturbing the routine space surveillance operations at U.S. Space Command (USSPACWCOM) and the Naval Space Surveillance Center (NAVSPASUR). This paper is a survey of some of the procedures and techniques used by NAVSPASUR to respond to such events. First, the overall data flow at NAVSPASUR is described highlighting the places at which human analysts may intervene with special processing. So-called manual intervention is required in a variety of non-nominal situations, including breakups. Second, a description is given of some of the orbital analysis and other software tools available to NAVSPASUR analysts. These tools were developed in-house over the past thirty years and can be employed in a highly flexible manner. The basic design philosophy for these tools was to implement simple concepts as efficiently as possible and to allow the analyst maximum use of his personal expertise. Finally, several historical breakup scenarios are discussed briefly. These scenarios provide examples of the types of questions that are fairly easy to answer in the present operational environment, as well as examples of questions that are very difficult to answer.

Schumacher, Paul W., Jr.

1991-01-01

174

A model of plate kinematics in Gondwana breakup  

NASA Astrophysics Data System (ADS)

An accurate model of relative plate motions in Gondwana breakup is based on visual fitting of seafloor isochrons and fracture zones (FZ) from the Riiser-Larsen Sea and Mozambique Basin. Used predictively, the model precisely locates kinematic markers in the West Somali Basin, which allows the conclusion that the spreading centres in the West Somali and Mozambique basins and the Riiser-Larsen Sea formed parts of the boundary between the same two plates. The locations of FZ and less well-defined isochrons from neighbouring regions are also consistent with their formation on other lengths of this same boundary and with its relocation from the West Somali Basin and northern Natal Valley to the West Enderby Basin and Lazarev Sea during chron M10n. Small independently moving plates thus played no role in the breakup of this core part of Gondwana. In an inversion procedure, the data from these areas yield more precise finite rotations that describe the history of the two plates' separation. Breakup is most simply interpreted to have occurred in coincidence with Karoo volcanism, and a reconstruction based on the rotations shows the Lebombo and Mateke-Sabi monoclines and the Mozambique and Astrid ridges as two sets of conjugate volcanic margins. Madagascar's pre-drift position can be used as a constraint to reassess the positions of India and Sri Lanka in the supercontinent.

Eagles, Graeme; König, Matthias

2008-05-01

175

Cryogenic liquid-jet breakup in two-fluid atomizers  

NASA Technical Reports Server (NTRS)

A two-fluid atomizer was used to study the breakup of liquid-nitrogen jets in nitrogen, argon, and helium atomizing gas flows. A scattered-light scanner particle sizing instrument previously developed at NASA Lewis Research Center was further developed and used to determine characteristic drop diameters for the cryogenic sprays. In the breakup regime of aerodynamic-stripping, i.e., sonic-velocity conditions, the following correlation of the reciprocal Sauter mean diameter, D(sub 32)exp -1, with the atomizing-gas flowrate, W(g), was obtained: D(sub 32)exp -1 = k(sub c)(W(g)exp 1.33), where k(sub c) is a proportionality constant evaluated for each atomizing gas. Values of k(sub c) = 120, 220, and 1100 were obtained for argon, nitrogen, and helium gasflows, respectively. The reciprocal Sauter mean diameter and gas flowrate have the units of 1/cm and g/sec, respectively. In the regime of capillary-wave breakup, or subsonic conditions, it was found that D(sub 32)exp -1 = k(g)(W(g)exp 0.75), where k = 270, 390, and 880 for argon, nitrogen, and helium gasflows, respectively.

Ingebo, Robert D.

1991-01-01

176

Electrical alternans and spiral wave breakup in cardiac tissue  

NASA Astrophysics Data System (ADS)

This paper reports the results of a theoretical investigation of spiral wave breakup in model equations of action potential propagation in cardiac tissue. A general formulation of these equations is described in which arbitrary experimentally determined restitution and dispersion curves can in principle be fitted. Spiral wave behavior is studied in two-dimension as a function of a parameter Re which controls the steepness of the restitution curve at short diastolic intervals. Spiral breakup is found to occur when the minimum period Tmin, below which a periodically stimulated tissue exhibits alternans in action potential duration, exceeds by a finite amount the spiral rotation period TS. At this point, oscillations in action potential duration are of sufficiently large amplitude to cause a spontaneous conduction block to form along the wavefront. The latter occurs closer to the initiation point of reentry (spiral tip) with increasing steepness and, hence, in smaller tissue sizes. Spiral breakup leads to a spatially disorganized wave activity which is always transient, except for tissues larger than some minimum size and within a very narrow range of Re which increases with dispersion.

Karma, Alain

1994-09-01

177

Transverse liquid fuel jet breakup, burning, and ignition  

SciTech Connect

An analytical/numerical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion first proposed by Schetz, et al. (1980). Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, have been used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flame supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic crossflow. Typical flame structures and concentration profiles have been calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integrated reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.

Li, H.

1990-12-31

178

Transverse liquid fuel jet breakup, burning, and ignition  

SciTech Connect

An analytical/numerical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion first proposed by Schetz, et al. (1980). Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, have been used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flame supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic crossflow. Typical flame structures and concentration profiles have been calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integrated reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.

Li, H.

1990-01-01

179

Beam breakup calculations for the second axis of DARHT  

SciTech Connect

The accelerator for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility will produce a 4-kA, 20-MeV, 2-{micro}s output electron beam with a design goal of less than 1000 {pi} mm-mrad normalized transverse emittance and less than 0.5-mm beam centroid motion. In order to meet this goal, the beam transport must have excellent optics and the beam breakup instability (BBU) must be limited in growth. Using a number of simulation codes such as AMOS and BREAKUP, we have modeled the transverse impedances of the DARHT-II accelerator cells and the electron beam response to different transverse excitations such as injector RF noise, magnetic dipole fields arising from the 90-degree bend between the cathode stalk and insulator column, and downstream solenoid alignment errors. The very low Q ({approx}2) predicted for the most important TM dipole modes has prompted us to extend the BREAKUP code to be able to use the dipole wakefields calculated by AMOS in addition to the most usual discrete frequency BBU mode model. We present results for the predicted BBU growth and the empirical sensitivity to various machine parameters.

Fawley, William M.; Chen, Y.-J.; Houck, T.L.

1999-08-20

180

Time Reversal Invariance Violation in Neutron Deuteron Scattering  

E-print Network

Time reversal invariance violating (TRIV) effects for low energy elastic neutron deuteron scattering are calculated for meson exchange and EFT-type of TRIV potentials in a Distorted Wave Born Approximation, using realistic hadronic strong interaction wave functions, obtained by solving three-body Faddeev equations in configuration space. The relation between TRIV and parity violating observables are discussed.

Young-Ho Song; Rimantas Lazauskas; Vladimir Gudkov

2011-04-15

181

Hard pion exchange currents and the backward deuteron disintegration  

NASA Astrophysics Data System (ADS)

Relation between exchange currents and a potential is discussed in the framework of the Schroedinger-like scheme. Backward deuteron disintegration is studied using the Paris and Reid soft-core potentials and the static hard pion exchange currents up to the order ?

Truhlik, E.; Adam, J.

182

JLAB Measurements of the Deuteron Electric and Magnetic Form Factors  

SciTech Connect

Large-momentum transfer JLab measurements of the deuteron electric and magnetic form factors are reported. The data are compared to theoretical models based on the relativistic impulse approximation with the inclusion of meson-exchange currents, and to predictions of quark-dimensional scaling and perturbative QCD.

Gerassimos G. Petratos

2000-12-12

183

Radiative Corrections to Neutrino Reactions off Proton and Deuteron  

E-print Network

Radiative corrections are calculated for antineutrino proton quasielastic scattering, neutrino deuteron scattering, and the asymmetry of polarised neutron beta decay from which $G_{A}/G_{V}$ is determined. A particular emphasis is given to the constant parts that are usually absorbed into the coupling constants, and thereby those that appear in the processes that concern us are unambiguously tied among each other.

T. Kubota; M. Fukugita

2004-10-01

184

Spin Structure Moments of the Proton and Deuteron  

SciTech Connect

Moments of the spin structure functions g1 and g2 of the proton and deuteron have been measured in the resonance region at intermediate four momentum transfer. We perform a Nachtmann moment analysis of this data, along with isovector and isoscalar combinations, in order to rigorously account for target mass effects. This analysis provides the first definitive evidence for dynamic higher twists.

Slifer, Karl; Rondon-Aramayo, Oscar; Aghalaryan, Aram; Ahmidouch, Abdellah; Asaturyan, Razmik; Bloch, Frederic; Boeglin, Werner; Bosted, Peter; Carasco, Cedric; Carlini, Roger; Cha, Jinseok; Chen, Jian-Ping; Christy, Michael; Cole, Leon; Coman, Luminita; Crabb, Donald; Danagoulian, Samuel; Day, Donal; Dunne, James; Elaasar, Mostafa; Ent, Rolf; Fenker, Howard; Frlez, Emil; Gaskell, David; Gan, Liping; Gomez, Javier; Hu, Bitao; Jourdan, Juerg; Jones, Mark; Keith, Christopher; Keppel, Cynthia; Khandaker, Mahbubul; Klein, Andreas; Kramer, Laird; Liang, Yongguang; Lichtenstadt, Jechiel; Lindgren, Richard; Mack, David; McKee, Paul; McNulty, Dustin; Meekins, David; Mkrtchyan, Hamlet; Nasseripour, Rakhsha; Niculescu, Maria-Ioana; Normand, Kristoff; Norum, Blaine; Pocanic, Dinko; Prok, Yelena; Raue, Brian; Reinhold, Joerg; Roche, Julie; Rohe, Daniela; Savvinov, Nikolai; Sawatzky, Bradley; Seely, Mikell; Sick, Ingo; Smith, C.; Smith, G.; Stepanyan, Samuel; Tang, Liguang; Tajima, Shigeyuki; Testa, Giuseppe; Vulcan, William; Wang, Kebin; Warren, G.; Wesselmann, Frank; Wood, Stephen; Yan, Chen; Yuan, Lulin; Yun, Junho; Zeier, Markus; Guo Zhu, Hong

2009-01-01

185

Characterization of the 2012-044C Briz-M Upper Stage Breakup  

NASA Technical Reports Server (NTRS)

The NASA breakup model prediction was close to the observed population for catalog objects. The NASA breakup model predicted a larger population than was observed for objects under 10 cm. The stare technique produces low observation counts, but is readily comparable to model predictions. Customized stare parameters (Az, El, Range) were effective to increase the opportunities for HAX to observe the debris cloud. Other techniques to increase observation count will be considered for future breakup events.

Hamilton, Joseph A.; Matney, Mark

2013-01-01

186

Commissioning and operation of the deuteron injector for PKUNIFTY project  

NASA Astrophysics Data System (ADS)

PKUNIFTY (PeKing University Neutron Imaging FaciliTY), a thermal neutron imaging facility based on a 2 MeV RFQ accelerator, has been constructed at Peking University. Its deuteron injector, which consists of a 2.45 GHz permanent magnet electron cyclotron resonance (PMECR) deuteron ion source and a two-solenoid low energy beam transport (LEBT), aims at producing and delivering 50 mA, 50 keV deuteron beam with a duty factor of 10% (1 ms, 100 Hz). In the preliminary tests of RFQ accelerator, the ECR ion source and LEBT are required to operate at various duty factors (from 1% to 10%). The deuteron ion source has been tested with different pulse widths for this reason. In order to optimize the transmission parameters, the beam current at the exit of RFQ as a function of solenoids tuning and steering magnets tuning are carefully studied. The beam emittance at the entrance of RFQ has been measured with space charge compensation by different argon gas (RG) pressure from 1.6 × 10-4 Pa to 4.7 × 10-3 Pa. The measuring results show the best compensating pressure is 3.5 × 10-3 Pa with a minimal normalized rms emittance of 0.12 pi mm mrad. During the commissioning, we found the purity of deuteron gas is an important factor which severely affects ECR discharge and plasma intensity inside the ion source chamber. The detailed experimental results obtained during the commissioning are discussed in this paper.

Ren, H. T.; Peng, S. X.; Lu, P. N.; Zhao, J.; Zhou, Q. F.; Song, Z. Z.; Yuan, Z. X.; Yu, J. X.; Guo, Z. Y.; Chen, J. E.

2014-02-01

187

Commissioning and operation of the deuteron injector for PKUNIFTY project.  

PubMed

PKUNIFTY (PeKing University Neutron Imaging FaciliTY), a thermal neutron imaging facility based on a 2 MeV RFQ accelerator, has been constructed at Peking University. Its deuteron injector, which consists of a 2.45 GHz permanent magnet electron cyclotron resonance (PMECR) deuteron ion source and a two-solenoid low energy beam transport (LEBT), aims at producing and delivering 50 mA, 50 keV deuteron beam with a duty factor of 10% (1 ms, 100 Hz). In the preliminary tests of RFQ accelerator, the ECR ion source and LEBT are required to operate at various duty factors (from 1% to 10%). The deuteron ion source has been tested with different pulse widths for this reason. In order to optimize the transmission parameters, the beam current at the exit of RFQ as a function of solenoids tuning and steering magnets tuning are carefully studied. The beam emittance at the entrance of RFQ has been measured with space charge compensation by different argon gas (RG) pressure from 1.6 × 10(-4) Pa to 4.7 × 10(-3) Pa. The measuring results show the best compensating pressure is 3.5 × 10(-3) Pa with a minimal normalized rms emittance of 0.12 pi?mm?mrad. During the commissioning, we found the purity of deuteron gas is an important factor which severely affects ECR discharge and plasma intensity inside the ion source chamber. The detailed experimental results obtained during the commissioning are discussed in this paper. PMID:24593440

Ren, H T; Peng, S X; Lu, P N; Zhao, J; Zhou, Q F; Song, Z Z; Yuan, Z X; Yu, J X; Guo, Z Y; Chen, J E

2014-02-01

188

Coalescence and Breakup of Oppositely Charged Droplets  

PubMed Central

The coalescence process of oppositely charged drops for different electrical conductivities of liquids is presented. When the electrical conductivity was relatively low, oppositely charged drops failed to coalesce under sufficiently high electrical fields and capillary ripples were formed on the surfaces of droplets after rebound. For a high electrically conductive liquid, it was found that a crown profile of drop fission always appeared on the top surface of negatively charged drops after the two charged drops contacted and bounced off. Furthermore, we report here, for the first time, the newly found phenomenon and argue that the break up might be caused by Rayleigh instability, a form of Coulomb fission. The different mobility of positive and negative ions is the underlying mechanism that explains why the break up always happened on the negative side of charged drops. PMID:25410022

Wang, Junfeng; Wang, Bin; Qiu, Huihe

2014-01-01

189

Breakup time scale studied in the 8 GeV/c pi- + 197Au reaction  

E-print Network

Experimental data from the reaction of an 8.0 GeV/c pi- beam incident on a 197Au target have been analyzed in order to investigate the integrated breakup time scale for hot residues. Alpha-particle energy spectra and particle angular distributions supported by a momentum tensor analysis suggest that at large excitation energy, above 3-5 MeV/nucleon, light-charged particles are emitted prior to or at the same time as the emission of the heavy fragments. Comparison with the SMM and GEMINI models is presented. A binary fission-like mechanism fits the experimental data at low excitation energies, but seems unable to reproduce the data at excitation energies above 3-5 MeV/nucleon.

L. Pienkowski; K. Kwiatkowski; T. Lefort; W. -c. Hsi; L. Beaulieu; A. Botvina; B. Back; H. Breuer; S. Gushue; R. G. Korteling; R. Laforest; E. Martin; E. Ramakrishnan; L. P. Remsberg; D. Rowland; A. Ruangma; V. E. Viola; E. Winchester; S. J. Yennello

2000-09-16

190

The visibility of color breakup and a means to reduce it.  

PubMed

Color breakup is an artifact seen on displays that present colors sequentially. When the eye tracks a moving object on such a display, different colors land on different places on the retina, and this gives rise to visible color fringes at the object's leading and trailing edges. Interestingly, color breakup is also observed when the eye is stationary and an object moves by. Using a novel psychophysical procedure, we measured breakup both when viewers tracked and did not track a moving object. Breakup was somewhat more visible in the tracking than in the non-tracking condition. The video frames contained three subframes, one each for red, green, and blue. We spatially offset the green and blue stimuli in the second and third subframes, respectively, to find the values that minimized breakup. In the tracking and non-tracking conditions, spatial offsets of ?x/3 in the second subframe (where ?x is the displacement of the object in one frame) and 2?x/3 in the third eliminated breakup. Thus, this method offers a way to minimize or even eliminate breakup whether the viewer is tracking or not. We suggest ways to implement the method with real video content. We also developed a color-breakup model based on spatiotemporal filtering in color-opponent pathways in early vision. We found close agreement between the model's predictions and the experimental results. The model can be used to predict breakup for a wide variety of conditions. PMID:25527148

Johnson, Paul V; Kim, Joohwan; Banks, Martin S

2014-01-01

191

An Analysis of Recent Major Breakups in the Low Earth Orbit Region  

NASA Technical Reports Server (NTRS)

Of the 4 recent major breakup events, the FY-1C ASAT test and the collision between Iridium 33 and Cosmos 2251 generated the most long-term impact to the environment. About half of the fragments will still remain in orbit at least 20 years after the breakup. The A/M distribution of the Cosmos 2251 fragments is well-described by the NASA Breakup Model. Satellites made of modern materials (such as Iridium 33), equipped with large solar panels, or covered with large MLI layers (such as FY-1C) may generated significant amount of high A/M fragments upon breakup.

Liou, J.-C.; Anz-Meador, P. D.

2010-01-01

192

The visibility of color breakup and a means to reduce it  

PubMed Central

Color breakup is an artifact seen on displays that present colors sequentially. When the eye tracks a moving object on such a display, different colors land on different places on the retina, and this gives rise to visible color fringes at the object's leading and trailing edges. Interestingly, color breakup is also observed when the eye is stationary and an object moves by. Using a novel psychophysical procedure, we measured breakup both when viewers tracked and did not track a moving object. Breakup was somewhat more visible in the tracking than in the non-tracking condition. The video frames contained three subframes, one each for red, green, and blue. We spatially offset the green and blue stimuli in the second and third subframes, respectively, to find the values that minimized breakup. In the tracking and non-tracking conditions, spatial offsets of ?x/3 in the second subframe (where ?x is the displacement of the object in one frame) and 2?x/3 in the third eliminated breakup. Thus, this method offers a way to minimize or even eliminate breakup whether the viewer is tracking or not. We suggest ways to implement the method with real video content. We also developed a color-breakup model based on spatiotemporal filtering in color-opponent pathways in early vision. We found close agreement between the model's predictions and the experimental results. The model can be used to predict breakup for a wide variety of conditions. PMID:25527148

Johnson, Paul V.; Kim, Joohwan; Banks, Martin S.

2014-01-01

193

Breakup of a finite length fluid film  

NASA Astrophysics Data System (ADS)

We study the process of dewetting of thin liquid films using a long-wave approximation for the film thickness, h, under partial wetting conditions. The governing equation for h includes the effects of surface tension as well as those of the gravity force, and incorporates an additional conjoining/disjoining pressure term to account for intermolecular forces. We perform standard linear stability analysis of infinite flat films, and identify the corresponding stable, unstable and metastable regions. Within this framework, we analyze the evolution of a semi-infinite film of length L in one direction. The numerical simulations show that for long and thin films, the dewetting at the extremes of the strip generates a pearling process consisting of successive stages of formation of bumps at the ends and consecutive pinch off behind these bumps. On the other hand, for shorter and thicker films, the evolution ends up by forming a single central drop. The time evolution as well as the final drops pattern shows a competition between the dewetting mechanisms caused by nucleation and by free surface instability.

Diez, Javier; Kondic, Lou

2006-11-01

194

Tear Film Images and Breakup Analyzed Using Fluorescent Quenching  

PubMed Central

Purpose. Tear evaporation should increase fluorescein concentration, causing fluorescence dimming from self-quenching for high but not low fluorescein concentration. This prediction was tested and compared to the predicted effect of “tangential flow” that fluorescence dimming should be similar for high and low concentrations. Methods. A custom optical system was used for video recording of tear film fluorescence in 30 subjects. The subjects were asked to blink at the start of the recording and try to keep their eyes open for the rest of the 60-second recording. An initial recording was made after instillation of 1 ?L 0.1% fluorescein followed by further recordings at 5-minute intervals using 0.5% and 5% fluorescein. Results. Decay of fluorescence was considerably greater for the high (5%) concentration condition than for the low (0.1%) concentration. This is shown by “ratio images” (ratio of the intensity of a fluorescence image at a later time divided by that of an earlier image), fluorescence decay curves, fluorescence decay rates, and histograms of estimated tear thickness decrease. For example, for the high concentration condition, decay rates were higher than for the low concentration for all 30 subjects (P < 0.0001, binomial test). Additionally, breakup time was significantly reduced for the high compared to the low concentration condition. Conclusions. The greater fluorescence decay and more rapid breakup for the high concentration condition are the results expected if thinning and breakup are mainly due to evaporation, hence causing self-quenching. Fluorescence decay rate for the low concentration condition was not significantly greater than zero. PMID:23920365

King-Smith, P. Ewen; Ramamoorthy, Padmapriya; Braun, Richard J.; Nichols, Jason J.

2013-01-01

195

Radial electron-beam-breakup transit-time oscillator  

DOEpatents

A radial electron-beam-breakup transit-time oscillator (RBTO) provides a compact high power microwave generator. The RBTO includes a coaxial vacuum transmission line having an outer conductor and an inner conductor. The inner conductor defines an annular cavity with dimensions effective to support an electromagnetic field in a TEM.sub.00m mode. A radial field emission cathode is formed on the outer conductor for providing an electron beam directed toward the annular cavity electrode. Microwave energy is then extracted from the annular cavity electrode.

Kwan, Thomas J. T. (Los Alamos, NM); Mostrom, Michael A. (Albuquerque, NM)

1998-01-01

196

Dynamical Relativistic Effects in Breakup Processes of Halo Nuclei  

NASA Astrophysics Data System (ADS)

The continuum-discretized coupled-channels (CDCC) method is used to study the breakup of weakly-bound nuclei at intermediate energies collisions. For large impact parameters, the Eikonal CDCC (E-CDCC) method was applied. The effects of Lorentz contraction on the nuclear and Coulomb potentials have been investigated in details. Such effects tend to increase cross sections appreciably. We also show that, for loosely-bound nuclei, the contribution of the so-called close field is small and can be neglected.

Ogata, K.; Bertulani, C. A.

2010-04-01

197

North Atlantic Margins: Case studies of Magmatic Continental Breakup  

NASA Astrophysics Data System (ADS)

Continental breakup between Europe and Greenland was accompanied by the rapid eruption of the > 1 million cubic kilometres of extruded basalts forming North Atlantic Igneous Province. With episodes of extension in the region dating back to the Devonian, rifting finally proceeded to full breakup and oceanic spreading in the Paleocene. Flood basalt units flowed up to 150 km over pre-existing sedimentary basins, discrete volcanic centres formed and intrusion into the thinned continental crust occurred. Marine seismic investigations utilising industry-leading seismic reflection imaging technologies and large deployments of ocean bottom seismometers across the Faroes and Hatton Bank margins have been used to better resolve margin structure and composition, improving our understanding of breakup processes. Seismic reflection imaging reveals sub-aerial and submarine seaward-dipping reflector sequences tracking the interplay of uplift (transient and permanent), crustal loading through extrusion and ongoing extension. Lower crustal reflectors, cross-cutting the continental fabric and interpreted as intrusions, are observed within the narrow continent-ocean transition. P-wave tomography of wide-angle reflections and refractions, recorded to offsets of up to ~200 km, reveals unusually thick oceanic crust with lower crustal velocities in excess of those expected for MORB compositions. High P-wave velocities are attributed to magnesium-rich compositions which, combined with the large oceanic crustal thickness, would be consistent with an elevated mantle temperature (~150°C higher than 'normal') at the time of breakup. Vp/Vs ratios derived from tomography of converted shear wave phases also support high magnesium melt composition. P-wave velocities and Vp/Vs ratios across the continent-ocean transition show a mixing trend between magnesium-rich gabbroic compositions (100% for oceanic crust) and compositions consistent with the Lewisian gneiss basement or Early Proterozoic metamorphic basement of the Faroes and Hatton Bank areas respectively. Sedimentary units forming a low velocity zone beneath the flood basalts across the Faroe Ridge and into the Faroe-Shetland Trough are hypothesised to represent Paleocene sedimentary rock emplaced as transient thermal uplift across the nascent rift zone led to increased weathering and clastic sediment transport from Greenland.

Eccles, J. D.; White, R. S.; Christie, P. A. F.

2012-04-01

198

Nuclear Magnetic Resonance System for a Polarized Deuteron Target  

NASA Astrophysics Data System (ADS)

The polarized target group at TUNL uses NMR to continuously monitor the polarization of a dynamically polarized proton target for n-p scattering experiments. The target is now being modified to handle a deuteron sample. Deuteron NMR measurements are dominated by a low signal to noise ratio and therefore averaging over many frequency sweeps is required to extract the thermal equlibrium signal. This technique requires minimizing NMR baseline instabilities over a frequency range of ± 250 KHz. A varactor, with applied bias determined by a PC running Labview, added in series with the tank circuit will allow fine adjustments of the resonant frequency to maximize signal sensitivity over the entire spectrum. The main source of systematic drift is the temperature dependent electrical properties of the coaxial cable which can be removed by stabilizing the temperature of the electronics and cable with a water bath.

Poole, J. O.; Gould, C. R.; Haase, D. G.; Raichle, B. W.; Walston, J. R.; Seely, M. L.; Tornow, W.

1997-11-01

199

Spin Manipulating Vector and Tensor Polarized Deuterons Stored in COSY  

NASA Astrophysics Data System (ADS)

We recently studied spin flipping and spin manipulation of a simultaneously vector and tensor polarized deuteron beam stored in the COSY Cooler Synchrotron at 1.85 GeV/c. Using the EDDA detector we calibrated vector and tensor analyzing powers, which were earlier unknown at this energy; thus, we were able to obtain the absolute values for both the vector and tensor polarizations. We manipulated the deuteron's polarization using a new water-cooled ferrite rf dipole, by adiabatically sweeping its frequency through an rf-induced spin resonance. We first experimentally determined the resonance's frequency and then varied the dipole's frequency range and frequency ramp time. This allowed us to maximize the vector polarization spin-flip efficiency to about 97 ± 1%. We also studied the interesting tensor polarization manipulation in considerable detail.

Morozov, Vassili; Krisch, Alan; Leonova, Maria; Raymond, Richard; Sivers, Dennis; Wong, Victor; Yonehara, Katsuya; Bechstedt, Ulf; Gebel, Ralf; Lehrach, Andreas; Lorentz, Bernd; Maier, Rudolf; Schnase, Alexander; Stockhorst, Hans; Eversheim, Dieter; Hinterberger, Frank; Rohdjess, Heiko; Ulbrich, Kay

2004-05-01

200

Deuteron production and elliptic flow in relativistic heavy ion collisions  

SciTech Connect

The hadronic transport model ART is extended to include the production and annihilation of deuterons via the reactions BB{r_reversible}dM, where B and M stand for baryons and mesons, respectively, as well as their elastic scattering with mesons and baryons in the hadronic matter. This new hadronic transport model is used to study the transverse momentum spectrum and elliptic flow of deuterons in relativistic heavy ion collisions, with the initial hadron distributions after hadronization of the produced quark-gluon plasma taken from a blast wave model. The results are compared with those measured by the PHENIX and STAR Collaborations for Au+Au collisions at {radical}(s{sub NN})=200 GeV and also with those obtained from the coalescence model based on freeze-out nucleons in the transport model.

Oh, Yongseok [Cyclotron Institute and Physics Department, Texas A and M University, College Station, Texas 77843 (United States); Korea Institute of Science and Technology Information, Daejeon 305-806 (Korea, Republic of); Lin Ziwei [Department of Physics, East Carolina University, Greenville, North Carolina 27858 (United States); Ko, Che Ming [Cyclotron Institute and Physics Department, Texas A and M University, College Station, Texas 77843 (United States)

2009-12-15

201

The effects of nozzle geometry on waterjet breakup at high Reynolds numbers  

Microsoft Academic Search

Waterjet breakup is traditionally considered to follow the Ohnesorge classification. In this classification, high Reynolds number waterjets are considered to atomize quickly after discharge. By generating a constricted waterjet where the water flow stays detached all the way through the nozzle, we have observed the first wind-induced breakup mode at high Reynolds numbers. Such a peculiar behavior, however, was not

H. Vahedi Tafreshi; B. Pourdeyhimi

2003-01-01

202

Predicting Fall Semester Breakups in College Roommates: A Replication Using the Social Satisfaction Questionnaire.  

ERIC Educational Resources Information Center

Undergraduates living in residence halls (n=578) completed the Social Satisfaction Questionnaire (SSQ). SSQ scores predicted subsequent roommate breakups resulting from interpersonal conflict. The prediction of breakup provided by SSQ scores was superior to that for demographic variables, other indices of the relationship quality, and general…

Lovejoy, M. Christine; And Others

1995-01-01

203

Deformation and breakup of high-viscosity droplets with symmetric microfluidic cross flows Thomas Cubaud*  

E-print Network

Deformation and breakup of high-viscosity droplets with symmetric microfluidic cross flows Thomas, 47.61.Jd The shape of high-viscosity droplets translating in a straight square microchannel can deformation rate, and the breakup of high-viscosity ratio droplets is inhibited in simple shear flows 4

Cubaud, Thomas

204

Experimental studies of the beam-breakup mode on ETA: comparison with theory  

SciTech Connect

The beam breakup mode has been observed and measured on ETA. Comparison between the measurements and the results of a computer code indicate that the beam breakup instability will be the most important limitation on current transport thru ATA. ETA Experiments that will enable a more accurate determination of the magnitude of the instability on ATA are discussed.

Caporaso, G.J.; Struve, K.W.

1982-01-29

205

An investigation of soft launch and instability breakup with a two-stage light gas gun  

SciTech Connect

Exploratory research has been performed in the use of a two-stage light gas gun facility to investigate the soft acceleration and breakup physics of rapidly launched thin plates. A flash radiograph system was joined with the gun facility to provide the principal diagnostic. In the study, radiographs of thin-plate acceleration and breakup were obtained.

Grady, D.E.; Moody, R.L.

1988-05-01

206

Theoretical and empirical analysis of the average cross-sectional areas of breakup fragments  

Microsoft Academic Search

This paper compares two different approaches to calculate the average cross-sectional area of breakup fragments. The first one is described in the NASA standard breakup model 1998 revision. This approach visually classifies fragments into several shapes, and then applies formulae developed for each shape to calculate the average cross-sectional area. The second approach was developed jointly by the Kyushu University

T. Hanada; J.-C. Liou

2011-01-01

207

Formation of beads-on-a-string structures during break-up of viscoelastic filaments  

E-print Network

Break-up of viscoelastic filaments is pervasive in both nature and technology. If a filament is formed by placing a drop of saliva between a thumb and forefinger and is stretched, the filament’s morphology close to break-up ...

Bhat, Pardeep P.

208

Observation of the freezing line in a deuteron glass  

Microsoft Academic Search

The phase diagram of the deuteron glass Rb1-x(ND4)xD2PO4 has been determined experimentally in the entire range of concentration x. A recently introduced temperature-frequency plot has been used to analyze the shape of the dielectric relaxation spectrum, indicating that in the glassy regime the longest relaxation time diverges according to the Vogel-Fulcher law. The corresponding Vogel-Fulcher temperature has been identified as

Z. Kutnjak; R. Pirc; A. Levstik; I. Levstik; C. Filipic; R. Blinc; R. Kind

1994-01-01

209

Deuteron Spin Structure Functions in the Resonance and DIS Regions  

SciTech Connect

We derive relations between spin-dependent nuclear and nucleon g_1 and g_2 structure functions, valid at all Q^2, and in both the resonance and deep inelastic regions. We apply the formalism to the specific case of the deuteron, which is often used as a source of neutron structure information, and compare the size of the nuclear corrections calculated using exact kinematics and using approximations applicable at large Q^2.

S. Kulagin; W. Melnitchouk

2007-10-03

210

Spin structure functions: Proton / deuteron measurements in the resonance region  

SciTech Connect

The RSS experiment ran in Hall C at Jefferson Lab and measured the proton and deuteron beam-target asymmetries for parallel and perpendicular target fields over a W range from pion threshold to 1.9 GeV at Q{sup 2} {approx} 1.3 GeV{sup 2}. Preliminary results for the proton spin structure functions g{sub 1} and g{sub 2} are presented.

Mark Jones; RSS Collaboration

2006-02-01

211

Can one extract the pi-neutron scattering length from pi-deuteron scattering?  

E-print Network

We give a prove of evidence that the original power counting by Weinberg can be applied to estimate the contributions of the operators contributing to the pi-deuteron scattering length. As a consequence, pi-deuteron observables can be used to extract neutron amplitudes--in case of pi-deuteron scattering this means that the pi-neutron scattering length can be extracted with high accuracy. This result is at variance with recent claims. We discuss the origin of this difference.

A. Nogga; C. Hanhart

2005-11-02

212

Covariant spectator theory of np scattering: Deuteron magnetic moment  

NASA Astrophysics Data System (ADS)

The deuteron magnetic moment is calculated using two model wave functions obtained from 2007 high-precision fits to np scattering data. Included in the calculation are a new class of isoscalar np interaction currents, which are automatically generated by the nuclear force model used in these fits. After normalizing the wave functions, nearly identical predictions are obtained: model WJC-1, with larger relativistic P-state components, gives 0.863(2), while model WJC-2 with very small P-state components gives 0.864(2). These are about 1% larger than the measured value of the moment, 0.857 n.m., giving a new CST prediction for the size of the ??? exchange, and other purely transverse interaction currents that are largely unconstrained by the nuclear dynamics. The physical significance of these results is discussed, and general formulas for the deuteron form factors, expressed in terms of deuteron wave functions and a new class of interaction current wave functions, are given.

Gross, Franz

2014-06-01

213

Study of break-up reactions of light dicluster nuclei  

SciTech Connect

The light weakly-bound nucleus 7Li is studied within a dicluster {alpha} + t picture. Different observables obtained within our simple model are compared with previous calculations and experiments showing good agreement. In particular we calculate dipole and quadrupole electromagnetic response to the continuum. The energy distribution of B(E{lambda}) values are consistent with the energy weighted molecular sum rule and display a sizable contribution of non-resonant character arising from the weak binding property. The corresponding form factors for excitations to the continuum are used in a semiclassical coupled channel scheme to get estimates for the break-up cross section in a heavy ion reaction. The nuclear contribution is found to play an important role in the process for bombarding energies around the Coulomb barrier. The masses and charges ratios of the two clusters are shown to lead to features of the cluster halo that may significantly differ from the one usually associated with one-nucleon haloes. Various features of structural properties of weakly-bound dicluster nuclei may be studied with this simple formalism and their properties may be used to get accurate estimates for break-up cross-sections.

Fortunato, L.; Vitturi, A. [Dipartimento di Fisica 'G.Galilei', Universita di Padova, via Marzolo 8, I-35131 Padova (Italy); INFN, via Marzolo 8, I-35131 Padova (Italy)

2006-08-14

214

Coulomb breakup of $^{37}$Mg and its ground state structure  

E-print Network

We calculate Coulomb breakup of the neutron rich nucleus $^{37}$Mg on a Pb target at the beam energy of 244 MeV/nucleon within the framework of a finite range distorted wave Born approximation theory that is extended to include the effects of projectile deformation. In this theory, the breakup amplitude involves the full wave function of the projectile ground state. Calculations have been carried out for the total one-neutron removal cross section $(\\sigma_{-1n})$, the neutron-core relative energy spectrum, the parallel momentum distribution of the core fragment, the valence neutron angular, and energy-angular distributions. The calculated $\\sigma_{-1n}$ has been compared with the recently measured data to put constraints on the spin parity, and the one-neutron separation energy ($S_{-1n}$) of the $^{37}$Mg ground state ($^{37}$Mg$_{gs}$). The dependence of $\\sigma_{-1n}$ on the deformation of this state has also been investigated. Our study suggests that $^{37}$Mg$_{gs}$ is most likely to have a spin parity ...

Shubhchintak,; Chatterjee, R; Shyam, R; Tsushima, K

2015-01-01

215

Distribution of living Cupressaceae reflects the breakup of Pangea  

PubMed Central

Most extant genus-level radiations in gymnosperms are of Oligocene age or younger, reflecting widespread extinction during climate cooling at the Oligocene/Miocene boundary [?23 million years ago (Ma)]. Recent biogeographic studies have revealed many instances of long-distance dispersal in gymnosperms as well as in angiosperms. Acting together, extinction and long-distance dispersal are likely to erase historical biogeographic signals. Notwithstanding this problem, we show that phylogenetic relationships in the gymnosperm family Cupressaceae (162 species, 32 genera) exhibit patterns expected from the Jurassic/Cretaceous breakup of Pangea. A phylogeny was generated for 122 representatives covering all genera, using up to 10,000 nucleotides of plastid, mitochondrial, and nuclear sequence per species. Relying on 16 fossil calibration points and three molecular dating methods, we show that Cupressaceae originated during the Triassic, when Pangea was intact. Vicariance between the two subfamilies, the Laurasian Cupressoideae and the Gondwanan Callitroideae, occurred around 153 Ma (124–183 Ma), when Gondwana and Laurasia were separating. Three further intercontinental disjunctions involving the Northern and Southern Hemisphere are coincidental with or immediately followed the breakup of Pangea. PMID:22550176

Mao, Kangshan; Milne, Richard I.; Zhang, Libing; Peng, Yanling; Liu, Jianquan; Thomas, Philip; Mill, Robert R.; S. Renner, Susanne

2012-01-01

216

Fragment angular correlation in the breakup of 16O ions at 95 MeV/A  

NASA Astrophysics Data System (ADS)

Fragment angular correlations in projectile breakup reactions are very sensitive to interference between different multipolarities entering in the excitation-dissociation process of the projectile. In particular, it was proposed to disentangle L=1 and L=2 contributions in direct breakup reactions of 16O with low relative energy between the ? and 12C fragment, which are of astrophysical interest. We studied the experimental aspects of extracting those angular correlations in extreme kinematical conditions usually encountered in breakup experiments of astrophysical interest. The breakup of 95 MeV/A 16O projectiles induced by a 208Pb target was measured using the high-resolution spectrometer SPEG at Ganil for the coincident detection of the fragments. Sequential breakup via the 12.53 MeV level of 16O is analyzed in this framework and it favors an one-step M2 excitation of this level.

Tatischeff, V.; Kiener, J.; Aguer, P.; Bogaert, G.; Coc, A.; Disdier, D.; Ichihara, T.; Kraus, L.; Lefebvre, A.; Linck, I.; Mittig, W.; Motobayashi, T.; de Oliveira Santos, F.; Roussel-Chomaz, P.; Stephan, C.; Thibaud, J. P.

1998-04-01

217

The role of pion exchange in $\\eta$ meson photo production on the deuteron  

E-print Network

Incoherent $\\eta$ photoproduction on the deuteron is studied with the main emphasis on the role of final state interactions. In addition to the previously studied mechanisms of $NN$ and $\\eta N$ rescatterings, the role of an intermediate pion exchange is considered in detail, where first a pion is photoproduced on one nucleon and then rescatters into an $\\eta$ meson on the other, the spectator nucleon. It is found, that the role of this pion mediated contribution is comparable in size to that of $\\eta N$ rescattering. Results for total and semi-inclusive differential cross sections and associated polarization observables are presented. In particular polarization observables show a significant sensititvity to final state interactions.

Fix, A; Levchuk, M; Tammam, M

2015-01-01

218

The role of pion exchange in $?$ meson photo production on the deuteron  

E-print Network

Incoherent $\\eta$ photoproduction on the deuteron is studied with the main emphasis on the role of final state interactions. In addition to the previously studied mechanisms of $NN$ and $\\eta N$ rescatterings, the role of an intermediate pion exchange is considered in detail, where first a pion is photoproduced on one nucleon and then rescatters into an $\\eta$ meson on the other, the spectator nucleon. It is found, that the role of this pion mediated contribution is comparable in size to that of $\\eta N$ rescattering. Results for total and semi-inclusive differential cross sections and associated polarization observables are presented. In particular polarization observables show a significant sensititvity to final state interactions.

A. Fix; H. Arenhövel; M. Levchuk; M. Tammam

2015-01-01

219

Reply to comment by Alley et al. on ``Catastrophic ice shelf breakup as the source of Heinrich event icebergs''  

E-print Network

breakup as the source of Heinrich event icebergs,'' Paleoceanography, 20, PA1011, doi:10.1029/2004PA001118 breakup as the source of Heinrich event icebergs'' by C. L. Hulbe et al., Paleoceanogra- phy, PA1009 doi), Cat- astrophic ice shelf breakup as the source of Heinrich event icebergs, Paleoceanography, 19, PA

Boyce, C. Kevin

220

a Longitudinal-Transverse Separation of the Helium -3(ELECTRON, Electron-Deuteron Reaction.  

NASA Astrophysics Data System (ADS)

The differential cross section d^5 sigma/dOmega_{e}dOmega _{d}dE was measured at sqrt{Q^2}=418 MeV/c at the Bates Linear Accelerator Center, covering the range in missing momentum p_{m} from 0-90 MeV/c. The forward angle data were taken at an initial energy of 382.5 MeV and an electron scattering angle of 72^circ, for a virtual photon polarization of epsilon =.47. The backward angle data were taken at an initial energy of 265.3 MeV and an electron scattering angle of 122 ^circ for an epsilon =.13. Each momentum setting of the spectrometers covered a wide range in both missing momentum and Q ^2 and the coincidence acceptance was modelled with a Monte Carlo simulation of the three-body kinematics. Particle detectors and digital readout electronics were deployed on the magnetic spectrometers MEPS and OHIPS, including a new drift chamber readout system specifically for this experiment. Software for data acquisition and data analysis was written. The data were taken in approximately parallel kinematics so that the interference structure functions sigma_{LT} and sigma_{TT} vanish. Cross sections were normalized to the ^3He elastic cross section and the detection efficiency was measured on D(e,e^'d). The structure functions were projected to sqrt {Q^2}=420 MeV/c using the predictions of the two-body breakup model of Nagorny. A Rosenbluth -type separation was made on the data at two values of missing momentum. At p_{m}=22 MeV/c the longitudinal-to-transverse ratio was found to be 3.528+/-0.803+/-0.421 and at p_{m}=54 MeV/c was 3.752+/-1.450+/-1.910. This is in sharp disagreement with the longitudinal-to-transverse strength for free electron-deuteron scattering and provides a direct contradiction to the quasideuteron model. This is in rough agreement with models of both Laget and Nagorny. The longitudinal to transverse ratio can be attributed to an enhancement of the transverse current due to an isovector (spin-isospin flip transition) component, where the initial np-pair is in an S = 0,T = 1 state. The experimental data shows that there is a considerable effect due to np-correlations in the singlet state. Theoretical models approximately reproduce the transverse structure function S_ {T} but disagree with measured values of S_{L} by a factor of ~2.

Tripp, Christopher Scott

1995-01-01

221

Spatial and temporal patterns in river ice breakup observed with MODIS and AVHRR time series  

NASA Astrophysics Data System (ADS)

The timing of spring river ice breakup, a major annual event for physical, biological, and human systems on Arctic rivers, has been used to infer regional climate variations over the past century or more. Most observations of ice breakup are recorded as point data taken from selected ground-based stations. It is unknown whether these point observations are fully representative of breakup patterns elsewhere along the course of a river. Here, daily time series of MODIS and AVHRR satellite images are used to remotely sense spatial and temporal patterns in ice breakup along 1600-3300 km lengths of the Lena, Ob', Yenisey, and Mackenzie Rivers. The first day of predominantly ice-free water is visually identified and mapped for the years 1992-1993, 1995-1998, and 2000-2003, with a mean precision of ± 1.75 days. The derived breakup dates show high correlation with ground-based observations, though a slight trend towards earlier satellite-derived dates can be traced to differences in the way ice breakup date is defined. Large ice jams are often observed, particularly at confluences, though smaller ice jams may not be visible due to the limited spatial resolution of the imagery used. At the watershed scale, spatial patterns in breakup seem to be primarily governed by latitude, timing of the spring flood wave, and location of confluences with major tributaries. Interestingly, channel-scale factors such as slope, width, and radius of curvature, which are known to influence ice breakup at the reach scale, do not appear to be major factors at the scale observed here. The degree of similarity between interannual trends in breakup date at distant points along a river is generally high, which supports the use of point-scale data to infer regional climate variations. This similarity does not hold true for the Mackenzie River, where substantial spatial differences in breakup trends are observed. A new variable, spatially integrated breakup date (di), uses weighted spatial averaging to provide a more encompassing measure of breakup timing. The Ob' and Yenisey Rivers show similar trends in spatially integrated breakup date from year to year. In contrast, the Mackenzie and Lena show a remarkably consistent negative correlation, here attributed to sea surface temperature anomalies associated with the Pacific Decadal Oscillation Index.

Pavelsky, T. M.; Smith, L. C.

2004-12-01

222

D-Cluster Converter Foil for Laser-Accelerated Deuteron Beams: Towards Deuteron-Beam-Driven Fast Ignition  

SciTech Connect

Fast Ignition (FI) uses Petawatt laser generated particle beam pulse to ignite a small volume called a pre-compressed Inertial Confinement Fusion (ICF) target, and is the favored method to achieve the high energy gain per target burn needed for an attractive ICF power plant. Ion beams such as protons, deuterons or heavier carbon ions are especially appealing for FI as they have relative straight trajectory, and easier to focus on the fuel capsule. But current experiments have encountered problems with the 'converter-foil' which is irradiated by the Petawatt laser to produce the ion beams. The problems include depletion of the available ions in the convertor foils, and poor energy efficiency (ion beam energy/ input laser energy). We proposed to develop a volumetrically-loaded ultra-high-density deuteron deuterium cluster material as the basis for converter-foil for deuteron beam generation. The deuterons will fuse with the ICF DT while they slow down, providing an extra 'bonus' energy gain in addition to heating the hot spot. Also, due to the volumetric loading, the foil will provide sufficient energetic deuteron beam flux for 'hot spot' ignition, while avoiding the depletion problem encountered by current proton-driven FI foils. After extensive comparative studies, in Phase I, high purity PdO/Pd/PdO foils were selected for the high packing fraction D-Cluster converter foils. An optimized loading process has been developed to increase the cluster packing fraction in this type of foil. As a result, the packing fraction has been increased from 0.1% to 10% - meeting the original Phase I goal and representing a significant progress towards the beam intensities needed for both FI and pulsed neutron applications. Fast Ignition provides a promising approach to achieve high energy gain target performance needed for commercial Inertial Confinement Fusion (ICF). This is now a realistic goal for near term in view of the anticipated ICF target burn at the National Ignition Facility (NIF) in CA within a year. This will usher in the technology development Phase of ICF after years of research aimed at achieving breakeven experiment. Methods to achieve the high energy gain needed for a competitive power plant will then be a key developmental issue, and our D-cluster target for Fast Ignition (FI) is expected to meet that need.

Miley, George H.

2012-10-24

223

arXiv:nucl-ex/0002003v225Feb2000 Phenomenology of the deuteron electromagnetic form factors  

E-print Network

arXiv:nucl-ex/0002003v225Feb2000 Phenomenology of the deuteron electromagnetic form factors D. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic struc- ture. They can

Thomas Jefferson National Accelerator Facility

224

The Breakup Time of a Droplet in a Fully-Developed Turbulent Flow  

NASA Astrophysics Data System (ADS)

We extend the work of Martínez-Bazán et al(C. Martínez-Bazán, J.L. Montañes, J.C. Lasheras, On the Breakup of an Air Bubble Injected into a Fully-Developed Turbulent Flow, Part 1: Breakup Frequency, Part 2: Size PDF of the Resulting Daughter Bubbles), JFM (1999)., on the breakup of air bubbles in a fully-developed turbulent flow, to liquid-liquid systems. The evolution of the droplet size probability density function, pdf, resulting from the breakup of a jet of heptane injected at the centerline of a submerged, high Reynolds number water jet is measured using image processing techniques. We use the evolution of the droplet size pdf to calculate the frequency (inverse of breakup time) of droplet breakup over a range of turbulent intensities. For turbulent Weber numbers less than 100 (Wet = frac?\\overline? u^2D?), the droplet breakup frequency is shown to depend on the turbulent dissipation rate as g(?,D) ? ?^0.45± 0.03. An extension of the phenomenological model proposed by Martínez-Bazán et al, based on the kinematics of droplet deformation, is shown to be in agreement with the experimental data. The model indicates that the effect of dispersed-phase density is small. The effects of surface tension and viscosity are also discussed.

Eastwood, C. D.; Cartellier, A.; Lasheras, J. C.

1999-11-01

225

Droplet breakup in accelerating gas flows. Part 2: Secondary atomization  

NASA Technical Reports Server (NTRS)

An experimental investigation to determine the effects of an accelerating gas flow on the atomization characteristics of liquid sprays was conducted. The sprays were produced by impinging two liquid jets. The liquid was molten wax and the gas was nitrogen. The use of molten wax allowed for a quantitative measure of the resulting dropsize distribution. The results of this study, indicate that a significant amount of droplet breakup will occur as a result of the action of the gas on the liquid droplets. Empirical correlations are presented in terms of parameters that were found to affect the mass median dropsize most significantly, the orifice diameter, the liquid injection velocity, and the maximum gas velocity. An empirical correlation for the normalized dropsize distribution is also presented. These correlations are in a form that may be incorporated readily into existing combustion model computer codes for the purpose of calculating rocket engine combustion performance.

Zajac, L. J.

1973-01-01

226

Inadvertent Earth Reentry Breakup Analysis for the New Horizons Mission  

NASA Technical Reports Server (NTRS)

The New Horizons (NH) spacecraft was launched in January 2006 aboard an Atlas V launch vehicle, in a mission to explore Pluto, its moons, and other bodies in the Kuiper Belt. The NH spacecraft is powered by a Radioisotope Thermoelectric Generator (RTG) which encases multiple General Purpose Heat Source (GPHS) modules. Thus, a pre-launch vehicle breakup analysis for an inadvertent atmospheric reentry in the event of a launch failure was required to assess aerospace nuclear safety and for launch contingency planning. This paper addresses potential accidental Earth reentries analyzed at the Jet Propulsion Laboratory (JPL) which may arise during the ascent to parking orbit, resulting in a suborbital reentry, as well as a departure from parking orbit, resulting in an orbital reentry.

Ling, Lisa M.; Salama, Ahmed; Ivanov, Mark; McRonald, Angus

2007-01-01

227

Breakup Threshold Anomaly: New Manifestation of the Dispersion Relation  

E-print Network

It is pointed out that the usual threshold anomaly, found operative in the energy behavior of the imaginary and real parts of the optical potential representing the elastic scattering of tightly bound nuclei at near- and below-barrier energies, suffers a drastic qualitative change in the case of the elastic scattering of weakly bound projectile nuclei. Owing to the strong coupling to the breakup channel even at sub-barrier energies, the imaginary potential strength seems to increase as the energy is lowered down to below the natural, barrier, threshold, accompanied by a decrease in the real potential strength. This feature is consistent with the dispersion relation. It also clearly indicates the effective increase of the barrier height. The systems $^{9}$Be,$^{16}$O + $^{64}$Zn and $^{6,7}$Li + $^{138}$Ba are analyzed to illustrate this new phenomenon.

Chamon, L C; Hussein, M S

2006-01-01

228

Airfoil large eddy breakup devices for turbulent drag reduction  

NASA Technical Reports Server (NTRS)

It was determined from the present LaRC experiments that tandem, airfoil-shaped large eddy breakup (LEBU) devices can reduce local skin friction as much as 30 percent with a recovery region extending more than 100 boundary layer thicknesses downstream. These airfoils experience near laminar skin friction device drag and produce net drag reductions of up to 7 percent. In contrast to the thin plates used in previous experiments, these airfoils are more than 1000 time stiffer and hence have the potential to withstand the real flight environment (dynamic pressure 36 times larger than in low-speed wing tunnels). In addition, the higher Reynolds numbers of the present tests indicate drag reduction performance is at least as good (or better) as at lower Reynolds numbers.

Anders, J. B.

1986-01-01

229

From conjugate volcanic rifted margins to micro-continent formation: Double breakup development of the Norwegian-Greenland Sea  

NASA Astrophysics Data System (ADS)

We re-evaluate the structure and spreading evolution of the Norwegian-Greenland Sea and surrounding volcanic (rifted) margins based on new high-resolution aeromagnetic surveys. The new dataset combined with long-offset seismic and gravity data allow us to have a better understanding of the structure and evolution of the conjugate margin systems in the Norwegian-Greenland Sea from the rifting to the drifting stage. We particularly focus on the new JAS-12 aeromagnetic survey acquired between the Aegir Ridge and the Jan Mayen micro-continent, which was initially part of the Møre-Vøring-Greenland rift system. Combined with the previous NB-07 and JAS-05 surveys, our final compilation fully covers the continent-ocean transition and the whole oceanic spreading system from the Møre margin to the conjugate Jan Mayen micro-continent with high quality, high-resolution and reliable magnetic data. The new dataset allowed a new, consistent and precise interpretation of the magnetic polarity chrons and oceanic fractures, providing the basis for more accurate rotation poles estimation, and better basin and crustal reconstructions between Norway, Greenland and the Jan Mayen micro-continent. This dataset allowed us to clarify the pre- and post-breakup configurations of the rift system and discuss the mechanisms involved during the onset of the two phases of breakup leading to the micro-continent formation. Our observations and models suggest that the pre-breakup rift system evolved through a significant Late Jurassic-Cretaceous thinning phase. This episode led to a significant thinning of the continental crust and an exhumation of pre-existing lower crust. However, we have not been able to identify and/or validate any clear domains of exhumed and denudated serpentinised mantle. The first Eocene breakup is mostly characterised by severe magmatism (sill, SDRS). Lithospheric/asthenospheric processes leading to rift localisation do not necessarily represent a continuum of lithospheric deformation with the precedent thinning system. Diking and disconnected lithospheric plumbing are proposed to explain the Eocene breakup. After the first phase of continental breakup, two major phases of spreading influenced the Norwegian-Greenland Sea. Phase I (from C24 to C21r, ~54 to 49 Ma) marks the earliest phase of spreading, probably initiated in the central and outer part of the Møre Basin. During this period, the formation of overlapping systems and pseudo-fault development, indirectly influenced by the proto-margin segmentation, suggests the presence of additional micro-plates in the Norwegian-Greenland Sea. We also observed a significant change in the oceanic spreading system in the late Early Eocene. Based on observations from the surrounding areas, this supports a major and distinct tectonic and magmatic event in the Norwegian-Greenland Sea at around C21r (49-47.9 Ma), the beginning of a second phase. During Phase II, from C21r-C12 or possibly younger (48-<32 Ma) of the Norway Basin development, spreading rates decreased, spreading direction changed leading to the formation of unexpected N-S oriented oceanic fracture zones. Phase II probably coincides with the climax of extension and possibly local spreading that is suspected in the southern part of the Jan Mayen micro-continent forming a complex area of oceanic, transitional and continental fragments before its complete dislocation from East Greenland in Latest Oligocene.

Gernigon, Laurent; Blischke, Anett; Nasuti, Aziz; Olesen, Odleiv; Sand, Morten; Sveinn Arnarson, Thorarinn

2014-05-01

230

The northern slope of South China Sea: an ideal site for studying passive margin extension and breakup  

NASA Astrophysics Data System (ADS)

With the advance of hydrocarbon exploration into deep waters of the northern SCS, structural details from continental slope to deepsea basin have been revealed. A striking feature is the dramatic change in Cenozoic extension along and across the strike as well as with the time. Along strike the slope is seperated by lithospheric faults into segments with different amount of Cenozoic extension. The breakup occurred in the no-extension eastern segment (the Chaoshan depression), the most strongly extended central segment (the Baiyun sag) but failed in the western segment of intermediate extension (the Qingdongnan basin). This pattern violates the expectation that breakup occurs at first where the extension reached the maximum. In the central segment, the style of extension varies significantly in dip direction. Differing from the belts of half grabens in the shelf, the extension is expressed as a large downwarp (the Baiyun sag) in the slope, and as irregularly shaped sags (the Liwan sag) near the continental-oceanic boundary (COB). The Baiyun sag (BYS) is the largest and deepest sag in the Pearl River Mouth basin (PRMB). Long-cable MCS revealed that at the center of the BYS the crust thinned to <7 km. Grabens and half-grabens are seen only along the SW border of the BYS in Paleogene and did not control the main subsidence of the sag. In Neogene, swarms of NWW-striking small faults developed in the SW and NE flanks of the sag. These features indicate that ductile extension had dominated the formation of the BYS. Suppose the SCS started opening at 30 Ma (although no breakup unconformity found at 30 Ma in the ODP#1148 well adjacent to the COB), the anomalous post-breakup subsidence in the BYS exceeds that predicted by classical model by 1~2 km and occurred most strongly in several periods. Similar anomalous post-breakup subsidence has been observed also in the shelf. The Liwan sag (LWS) SE of the BYS is an aggregate of NS-, NW-, EW-, and NE-elongated narrow and short sags. Its complex shape differs from that of any other sag in the northern SCS, also differs from that of the lower slope of SE Atlantic margin and the Gulf of Mexico where thrust belts developed by gravitational sliding. Multi-staged magmatic activities have contributed to but could not fully explain the structural complexities of the LWS. Perhaps basement structures have played an important role as the sag might be developed upon the relict Mesozoic West Pacific subduction system. In addition, two horizons of deep-seated waving reflectors are identified beneath the LWS, which are suspected to be respectively a detachment surface and the intra-crustal shear zones related to lower-crust flow. A good understanding of these features may help answering the fundamental question on what controls the style, magnitude, and segmentation of passive margin extension and breakup, what is the mechanism, and what differences between marginal sea and open oceans in their evolution and dynamics. Preliminary attempt has been made taking into account basement structure, kinematics of bounding blocks, lithospheric rheology, lower crustal flow, as well as enhanced sediment supply by monsoon strengthening. This study is funded by CNSF40976033.

Zhou, D.; Sun, Z.; Pang, X.; Wu, X.; Xu, H.; Qiu, N.

2011-12-01

231

Coulomb breakup of $^{37}$Mg and its ground state structure  

E-print Network

We calculate Coulomb breakup of the neutron rich nucleus $^{37}$Mg on a Pb target at the beam energy of 244 MeV/nucleon within the framework of a finite range distorted wave Born approximation theory that is extended to include the effects of projectile deformation. In this theory, the breakup amplitude involves the full wave function of the projectile ground state. Calculations have been carried out for the total one-neutron removal cross section $(\\sigma_{-1n})$, the neutron-core relative energy spectrum, the parallel momentum distribution of the core fragment, the valence neutron angular, and energy-angular distributions. The calculated $\\sigma_{-1n}$ has been compared with the recently measured data to put constraints on the spin parity, and the one-neutron separation energy ($S_{-1n}$) of the $^{37}$Mg ground state ($^{37}$Mg$_{gs}$). The dependence of $\\sigma_{-1n}$ on the deformation of this state has also been investigated. Our study suggests that $^{37}$Mg$_{gs}$ is most likely to have a spin parity assignment of $3/2^-$. Using the shell model value for the spectroscopic factor for this configuration and without considering the projectile deformation effects, a $S_{-1n}$ of $0.10 \\pm 0.02$ MeV is extracted. Inclusion of the deformation effects increases the value of the deduced $S_{-1n}$. The narrow parallel momentum distribution of the core fragment and the strong forward peaking of the valence neutron angular distribution suggest a one-neutron halo configuration in the $2p_{3/2}$ ground state of $^{37}$Mg.

Shubhchintak; Neelam; R. Chatterjee; R. Shyam; K. Tsushima

2015-01-15

232

Observables in elastic electron-deuteron scattering with two-photon exchange  

NASA Astrophysics Data System (ADS)

The general form of the cross section as well as the polarizations of electron-deuteron elastic scattering are given. Two-photon exchange effects are analyzed. Possible signatures of the two-photon exchange effects in the electron-deuteron elastic scattering are discussed.

Dong, Yu Bing; Kao, Chung Wen; Yang, Shin Nan; Chen, Yu Chun

2006-12-01

233

Elastic and break-up of the 1n-halo 11Be nucleus  

NASA Astrophysics Data System (ADS)

The elastic and break-up angular distributions of the 10,11Be+64Zn reactions measured at Ec.m.?1.4 VC have been analysed within the CCDC and O.M. frameworks. The suppression of the Coulomb-nuclear interference, observed in the 11Be scattering case with respect to the 10Be, has been interpreted as due to a long range absorption owing to the coupling with the break-up (Coulomb and nuclear) channels. The presence of 10Be events on the 11Be experiment data have been explained as due mainly to break-up processes.

Di Pietro, A.; Moro, A. M.; Acosta, L.; Amorini, F.; Borge, M. J. G.; Figuera, P.; Fisichella, M.; Fraile, L. M.; Gomez-Camacho, J.; Jeppesen, H.; Lattuada, M.; Martel, I.; Milin, M.; Musumarra, A.; Papa, M.; Pellegriti, M. G.; Perez-Bernal, F.; Raabe, R.; Randisi, G.; Rizzo, F.; Scuderi, V.; Tengblad, O.; Torresi, D.; Vidal, A. Maira; Voulot, D.; Wenander, F.; Zadro, M.

2014-03-01

234

Explanation of 3He and triton rates in the alpha breakup inclusive cross sections  

NASA Astrophysics Data System (ADS)

(?, 3He) and (?, t) continuum inclusive spectra are measured on target nuclei ranging from 58Ni to 209Bi. Systematic differences in the absolute magnitudes of the 3He and triton spectra are found. To explain these differences the distorted-wave Born approximation calculations in the post form for inclusive breakup reactions are performed. It is shown that Coulomb effects are responsible for these differences. NUCLEAR REACTIONS (?, t), (?, 3He) breakup reactions: measured d2?d ? dE; targets: 58Ni, 90Zr, 120Sn, 209Bi; post form DWBA breakup theory.

Shyam, R.; Baur, G.; Budzanowski, A.; Bojowald, J.; Dabrowski, H.; Mayer-Böricke, C.; Oelert, W.; Riepe, G.; Rogge, M.; Turek, P.; Rösel, F.; Trautmann, D.

1983-05-01

235

A study of the paraelectric-ferroelectric phase transition of triglycine sulphate by deuteron nuclear magnetic resonance and relaxation  

Microsoft Academic Search

The quadrupole coupling (QC) tensors of the deuteron in all hydrogen positions are reported for the paraelectric (p) phase of triglycine sulphate (TGS), while for the ferroelectric (f) phase the authors restrict themselves to the deuterons in the 'long' and 'short' hydrogen bonds and to the ND3 deuterons of glycine GI. In addition, the orientation dependence of the spin-lattice relaxation

G. Slosarek; A. Heuer; H. Zimmermann; U. Haeberlen

1989-01-01

236

Linear relation between deuteron matter radius and the scattering length  

NASA Astrophysics Data System (ADS)

We explain the empirical linear relations between the triplet scattering length, or the asymptotic normalization constant, and the deuteron matter radius using the effective range expansion in a manner similar to a recent paper by Bhaduri et al. We emphasize the corrections due to the finite force range and to shape dependence. The discrepancy between the experimental values and the empirical line shows the need for a larger value of the wound extension, a parameter which we introduce here. Short-distance nonlocality of the n-p interaction is a plausible explanation for the discrepancy.

Sprung, D. W. L.; Wu, Hua; Martorell, J.

1990-09-01

237

Effective Theory for Neutron-Deuteron Scattering and the Triton  

E-print Network

We apply the effective field theory approach to the three-nucleon system. In particular, we consider neutron-deuteron scattering and the triton. Precise predictions for S=3/2 scattering are obtained in a straightforward way. In the S=1/2 channel, however, a unique nonperturbative renormalization takes place which requires the introduction of a three-body force at leading order. We also show that invariance under the renormalization group explains some universal features of the three-nucleon system.

H. -W. Hammer

1999-05-18

238

Effects of polymer concentration and molecular weight on the dynamics of visco-elasto-capillary breakup  

E-print Network

Capillary-break-up measurements of viscoelastic polymer solutions are performed using a Capillary Breakup Extensional Rheometer (CABER). The device consists of two coaxial plates which are used to form and hold a liquid ...

Verani, Matthieu, 1977-

2004-01-01

239

Theoretical quantum chemical study of protonated - deuteronated PAHs: Interstellar implications  

NASA Astrophysics Data System (ADS)

Diffuse Interstellar Bands (DIBs) are optical absorption features on the interstellar extinction curve. Ultra-high resolution spectroscopic observations suggest that at least some of these features are due to large molecules. Observational results also reveal that the strengths of the DIBs are not strongly correlated with each other, implying that there must be several carriers. Considering the wide range of interstellar species and the cost and duration of experimental work that is involved to determine the carriers of DIBs, Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) calculations offer opportunities to investigate which molecules are suitable for laboratory studies. The widespread presence of Polycyclic Aromatic Hydrocarbons (PAHs) in astrophysical environments is known from observations of the Unidentified Infrared (UIR) emission bands. Since PAHs are stable enough to be present under interstellar conditions, they are good candidates to be the carriers of the DIBs. We report DFT and TDDFT calculations to predict electronic transitions of neutral as well as protonated-deuteronated PAHs with various sites of protonation and deuteronation. The PAH molecules considered for calculation include pyrene, perylene, coronene and heptacene. Compared to their neutral forms, these charged isoelectronic forms of PAHs are predicted to have active transitions in the visible region, which means they are suitable candidates as carriers for some of the DIBs.

Buragohain, Mridusmita; Pathak, Amit; Hammonds, Mark; Sarre, Peter J.

2013-06-01

240

Spin manipulating vector & tensor polarized deuterons stored in COSY  

NASA Astrophysics Data System (ADS)

We recently studied the spin manipulation of a simultaneously vector and tensor polarized deuteron beam stored at 1.85 GeV/c in the COSY Cooler Synchrotron. Using the EDDA detector, we first calibrated the vector and tensor analyzing powers, which were earlier unmeasured at 1.85 GeV/c; this allowed us to measure the absolute values of both the vector and tensor polarizations. Then we manipulated the deuteron's polarization by sweeping the frequency of a ferrite rf dipole through an rf-induced spin resonance. We first experimentally determined the resonance's frequency and then varied the rf dipole's frequency sweep range ?f and frequency ramp time ?t to maximize the spin-flip efficiency. We then obtained a measured vector spin-flip efficiency of 98.5 ± 0.3% [1]. We also studied, in detail, the behavior of the tensor polarization during spin manipulation; these new data may allow a better understanding of the interesting quantum behavior of spin-1 bosons. This research was supported by the German BMBF Science Ministry. [1] V.S. Morozov et al., Phys. Rev. ST Accel. Beams 8, 061001 (2005).

Morozov, V. S.; Krisch, A. D.; Leonova, M. A.; Raymond, R. S.; Sivers, D. W.; Wong, V. K.; Yonehara, K.; Gebel, R.; Lehrach, A.; Lorentz, B.; Maier, R.; Prasuhn, D.; Schnase, A.; Stockhorst, H.; Eversheim, D.; Hinterberger, F.; Rohdjess, H.; Ulbrich, K.

2006-04-01

241

Faddeev-Yakubovsky Calculation above 4-BODY Break-Up Threshold  

NASA Astrophysics Data System (ADS)

This is the first attempt to solve the four-body Faddeev-Yakubovsky equation at an energy above the 4-body break-up threshold. The calculation is carried out with minimal inputs employing a separable type of the Paris potential, and numerical convergence is checked. About two digits convergence is obtained below the 4-body break-up threshold, however, one or less above that.

Uzu, Eizo; Kamada, Hiroyuki; Koike, Yasuro

2003-04-01

242

Three-body breakup in the dissociative recombination of the covalent triatomic molecular ion O3+.  

PubMed

We report the first observation of almost exclusive three-body breakup in the dissociative recombination of a covalent triatomic molecular ion O3+. The three-body channel, constituting about 94% of the total reactivity, has been investigated in detail. The atomic fragments are formed in only the first two electronic states, 3P and 1D, while formation in the 1S state has not been observed. The breakup predominantly proceeds through dissociative states with linear geometry. PMID:17677840

Zhaunerchyk, V; Geppert, W D; Larsson, M; Thomas, R D; Bahati, E; Bannister, M E; Fogle, M R; Vane, C R; Osterdahl, F

2007-06-01

243

Transition from continental break-up to punctiform seafloor spreading: How fast, symmetric and magmatic  

Microsoft Academic Search

We present a comparison between numerical and analogue models focusing on the role of inherited lithospheric structures in influencing the process of continental break-up. Our results highlight that the presence of pre-existing anisotropies localizes strain and favors continental break-up and formation of a new ocean. For a fixed strain rate, the pre-rift lithosphere configuration influences rift duration, melt production and

Giacomo Corti; Jolante Van Wijk; Marco Bonini; Dimitrios Sokoutis; Sierd Cloetingh; Fabrizio Innocenti; Piero Manetti

2003-01-01

244

Measuring the area of tear film break-up by image analysis software  

NASA Astrophysics Data System (ADS)

Tear film breakup time (BUT) test only examines the first break in the tear film, but subsequent tear film events are not monitored. We present a method of measuring the area of breakup after the appearance of the first breakup by using open source software. Furthermore, the speed of the rupture was determined. 84 subjects participated in the study. 2 ?l volume of 2% sodium fluorescein was instilled using a micropipette. The subject was seated behind a slit-lamp using a cobalt blue filter together with a Wratten 12 yellow filter. Then, the tear film was recorded by a camera attached to the slit lamp. 4 frames of each video was extracted, the first rupture (BUT_0), breakup after 1 second (BUT_1), rupture after 2 seconds (BUT_2) and breakup before the last blink (BUT_F). Open source software of measurement based on Java (NIH ImageJ) was used to measure the number of pixels in areas of breakup. These areas were divided by the area of exposed cornea to obtain the percentage of ruptures. Instantaneous breakup speed was calculated for second 1 as the difference between BUT_1 - BUT_0, whereas instant speed for second 2 was BUT_2 - BUT_1. Mean area of breakup obtained was: BUT_0 = 0.26%, BUT_1 = 0.48%, BUT_2 = 0.79% and BUT_F = 1.61%. Break speed was 0.22 area/sec for second 1 and 0.31 area/sec for second 2, showing a statistical difference between them (p = 0.007). Post BUT analysis may be easily monitoring with the aid of this software.

Pena-Verdeal, Hugo; García-Resúa, Carlos; Ramos, Lucía.; Mosquera, Antonio; Yebra-Pimentel, Eva; Giráldez, María. Jesús

2013-11-01

245

Effects of Breakup of Weakly Bound Projectile and Neutron Transfer on Fusion Reactions  

SciTech Connect

The excitation functions of elastic and quasielastic scattering at backward angles are measured for the systems 16O + 152Sm , 6,7Li + 208Pb. The barrier distributions are extracted from these measured excitation functions and compared with the corresponding fusion barrier distributions. Except some details, the barrier distributions derived from the data of fusion and elastic/quasielastic scattering are almost the same for the tightly bound reaction systems. For the reaction systems with weakly bound projectile, the barrier distributions extracted from quasielastic scattering are obviously different the fusion barrier distributions. However, the barrier distributions extracted from the excitation functions of the quasielastic scattering plus breakup are almost the same as the one extracted from the complete fusion data. This result means that barrier distribution not only bears the information of nuclear structures but also contains the knowledge of reaction mechanisms. In addition, the measured barrier distribution of 32S + 96Zr is flat and extends to lower energy due to the coupling of neutron transfer with positive Q-values, which will result in a significant enhancement effusion cross sections at the subbarrier energies. However, our results show that the complete fusion of the weakly bound projectile with heavy target is suppressed at the above barrier energies as compared with the model predictions.

Lin, C. J.; Zhang, H. Q.; Yang, F.; Ruan, M.; Liu, Z. H.; Wu, X. K.; Zhou, P.; Zhang, C. L.; Zhang, G. L.; An, G. P.; Jia, H. M.; Xu, X. X. [China Institute of Atomic Energy, P.O. Box 275 (10), Beijing 102413 (China)

2006-11-02

246

Breakup structure of two-phase jets with various momentum flux from a porous injector  

NASA Astrophysics Data System (ADS)

Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To increase atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear coaxial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial injector

Lee, Inchul; Kim, Dohun; Koo, Jaye

2014-02-01

247

Breakup of {sup 12}C resonances into three alpha particles  

SciTech Connect

The reaction {sup 3}He+{sup 11}B->d+{sup 12}C* has been used to populate resonances in {sup 12}C up to an excitation energy of 15 MeV. The subsequent breakup to three alpha particles has been measured in complete kinematics. Dalitz plots are used to visualize and analyze the data. The Dalitz plot intensity distribution exhibits zero points characteristic of the total spin and parity of the 3alpha system allowing us to determine the spin and parity of a state in {sup 12}C at 13.35 MeV whose quantum numbers were hitherto not well established. The Dalitz plot intensity distributions of the 2{sup -} state at 11.83 MeV and the 1{sup +} state at 12.71 MeV are compared with the predictions of a recent three-body calculation as well as with simpler models. All are able to reproduce the gross structures seen in the Dalitz plot, but none give an accurate description of the detailed profile of the distributions.

Kirsebom, O. S.; Fynbo, H. O. U.; Hyldegaard, S.; Riisager, K. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Alcorta, M.; Borge, M. J. G.; Cubero, M.; Dominguez-Reyes, R.; Madurga, M.; Perea, A.; Tengblad, O. [Instituto de Estructura de la Materia, CSIC, ES-28006 Madrid (Spain); Diget, C. A.; Fulton, B. R. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Fraile, L. M. [PH Department, CERN, CH-1211 Geneva 23 (Switzerland); Jonson, B.; Nilsson, T.; Nyman, G. [Fundamental Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Munoz Martin, A. [CMAM, Universidad Autonoma de Madrid, Cantoblanco, ES-28049 Madrid (Spain)

2010-06-15

248

Cheating, breakup, and divorce: is Facebook use to blame?  

PubMed

The purpose of the present study was to investigate the relationship between using the social networking site known as Facebook and negative interpersonal relationship outcomes. A survey of 205 Facebook users aged 18-82 was conducted using a 16-question online survey to examine whether high levels of Facebook use predicted negative relationship outcomes (breakup/divorce, emotional cheating, and physical cheating). It was hypothesized that those with higher levels of Facebook use would demonstrate more negative relationship outcomes than those with lower use. The study then examined whether these relationships were mediated by Facebook-related conflict. Furthermore, the researchers examined length of relationship as a moderator variable in the aforementioned model. The results indicate that a high level of Facebook usage is associated with negative relationship outcomes, and that these relationships are indeed mediated by Facebook-related conflict. This series of relationships only holds for those who are, or have been, in relatively newer relationships of 3 years or less. The current study adds to the growing body of literature investigating Internet use and relationship outcomes, and may be a precursor to further research investigating whether Facebook use attributes to the divorce rate, emotional cheating, and physical cheating. PMID:23745615

Clayton, Russell B; Nagurney, Alexander; Smith, Jessica R

2013-10-01

249

Panjal Paleomagnetism: Implications for Early Permian Gondwana break-up  

NASA Astrophysics Data System (ADS)

The mid-Early Permian represents an important phase in Pangaea's development marking the time when the >13,000 km-long string of terranes that are collectively known as 'Cimmeria' separated from Gondwana's Tethyan margin (northern Africa-NE Arabia-northern India-NW and northern Australia). The ~289 Ma Panjal Traps of NW India (Kashmir) are one of a number of mafic suites (Abor, Sikkim etc.) that were erupted onto the Indian block possibly during the separation of the Lhasa/SE Qiangtang block. Herein, we report data from the first modern paleomagnetic study of the unit. Results from four quarry sections (15 individual cooling units) from a locality close to Srinagar together form a tectonically coherent sequence spanning 2-3 km of stratigraphy. The derived direction and paleopole yield key new information concerning (1) the Early Permian location of India, and by inference that of central Gondwana, and (2) inform debates related to Cimmeria's breakup from eastern Gondwana. Moreover, they provide a new independent control for assessing NW Greater India's extent prior to its collision with Asia and the amount of vertical-axis rotation this sector of the Himalayan range experienced in the mid to late Cenozoic.

Stojanovic, D.; Aitchison, J.; Ali, J. R.; Ahmad, T.; Ahmad Dar, R.; Agarwal, A.; Roeder, T.

2013-12-01

250

Asteroid breakup linked to the Great Ordovician Biodiversification Event  

NASA Astrophysics Data System (ADS)

The rise and diversification of shelled invertebrate life in the early Phanerozoic eon occurred in two major stages. During the first stage (termed as the Cambrian explosion), a large number of new phyla appeared over a short time interval ~540Myrago. Biodiversity at the family, genus and species level, however, remained low until the second stage marked by the Great Ordovician Biodiversification Event in the Middle Ordovician period. Although this event represents the most intense phase of species radiation during the Palaeozoic era and led to irreversible changes in the biological make-up of Earth's seafloors, the causes of this event remain elusive. Here, we show that the onset of the major phase of biodiversification ~470Myrago coincides with the disruption in the asteroid belt of the L-chondrite parent body-the largest documented asteroid breakup event during the past few billion years. The precise coincidence between these two events is established by bed-by-bed records of extraterrestrial chromite, osmium isotopes and invertebrate fossils in Middle Ordovician strata in Baltoscandia and China. We argue that frequent impacts on Earth of kilometre-sized asteroids-supported by abundant Middle Ordovician fossil meteorites and impact craters-accelerated the biodiversification process.

Schmitz, Birger; Harper, David A. T.; Peucker-Ehrenbrink, Bernhard; Stouge, Svend; Alwmark, Carl; Cronholm, Anders; Bergström, Stig M.; Tassinari, Mario; Xiaofeng, Wang

2008-01-01

251

Droplet collisions after liquid jet breakup in microgravity conditions  

NASA Astrophysics Data System (ADS)

The droplet dynamics and collisions after a liquid jet breakup have been experimentally studied in low gravity conditions. An experimental setup was designed in order to be used at the I.N.T.A. Drop Tower, which allows for 2.1 seconds of microgravity. The dynamics of distilled water jets injected into a rectangular tank was recorded by means of a high-speed video camera. Observations of the droplet trajectories showed a conical shape of the liquid jet caused by droplet collisions just after detachment from the liquid jet. The detached droplets initially follow straight paths at constant velocity in the direction of injection. Deviation of these trajectories is a consequence of the collision between two droplets with an impact parameter slightly different from zero. The collision between two droplets can give rise to coalescence or bouncing between droplets depending on the droplet velocity difference and impact parameter. At low values of the relative velocity, the collision leads to coalescence between droplets, while at higher values the collision results in bouncing between droplets.

Suñol, F.; González-Cinca, R.

2011-12-01

252

Aerosol cluster impact and break-up : model and implementation.  

SciTech Connect

In this report a model for simulating aerosol cluster impact with rigid walls is presented. The model is based on JKR adhesion theory and is implemented as an enhancement to the granular (DEM) package within the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Modeling the interactions of small particles is relevant to a number of applications (e.g., soils, powders, colloidal suspensions, etc.). Modeling the behavior of aerosol particles during agglomeration and cluster dynamics upon impact with a wall is of particular interest. In this report we describe preliminary efforts to develop and implement physical models for aerosol particle interactions. Future work will consist of deploying these models to simulate aerosol cluster behavior upon impact with a rigid wall for the purpose of developing relationships for impact speed and probability of stick/bounce/break-up as well as to assess the distribution of cluster sizes if break-up occurs. These relationships will be developed consistent with the need for inputs into system-level codes. Section 2 gives background and details on the physical model as well as implementations issues. Section 3 presents some preliminary results which lead to discussion in Section 4 of future plans.

Lechman, Jeremy B.

2010-10-01

253

Complete set of deuteron analyzing powers for dp elastic scattering at intermediate energies  

NASA Astrophysics Data System (ADS)

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with polarized deuterons beams at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers ( iT 11, T 20, T 21, T 22) in deuteron-proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with the Tucson-Melbourne'99, and UrbanaIX three nucleon forces.

Sekiguchi, K.; Okamura, H.; Wada, Y.; Miyazaki, J.; Taguchi, T.; Gebauer, U.; Dozono, M.; Kawase, S.; Kubota, Y.; Lee, C. S.; Maeda, Y.; Mashiko, T.; Miki, K.; Sakaguchi, S.; Sakai, H.; Sakamoto, N.; Sasano, M.; Shimizu, Y.; Takahashi, K.; Tang, R.; Uesaka, T.; Wakasa, T.; Yako, K.

2014-01-01

254

Measurement of inelastic cross sections in relativistic deuteron-on-lead reactions  

SciTech Connect

The inelastic cross section of deuterons hitting a lead target has been determined by the beam attenuation technique. A spallation neutron source based on a lead target was irradiated with 1.6- and 2.5-GeV deuterons. Solid-state nuclear track detectors as well as the activation method were used to obtain the neutron and proton distribution along the surface of the source. The attenuation coefficient was estimated by fitting the experimental data and taking into account the buildup effect and the beam attenuation. Using the attenuation coefficient, the interaction length and then the inelastic cross section of deuterons on lead reaction were determined.

Zamani, M.; Stoulos, S.; Fragopoulou, M. [Aristotle University of Thessaloniki, School of Physics, GR-54 124 Thessaloniki (Greece); Krivopustov, M. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation)

2010-10-15

255

Polarization observables in lepton-deuteron elastic scattering including the lepton mass  

NASA Astrophysics Data System (ADS)

Expressions for the unpolarized differential cross section and for various polarization observables in the lepton-deuteron elastic scattering, ? +D ?? +D ,? =e ,? ,? , have been obtained in the one-photon-exchange approximation, taking into account the lepton mass. Polarization effects have been investigated for the case of a polarized lepton beam and polarized deuteron target which can have vector or tensor polarization. Numerical estimations of the lepton mass effects have been done for the unpolarized differential cross section and for some polarization observables and applied to the case of low-energy muon deuteron elastic scattering.

Gakh, G. I.; Gakh, A. G.; Tomasi-Gustafsson, E.

2014-12-01

256

Spectroscopic information of 6Li from elastic scattering of deuterons, 3He and 4He by 6Li  

NASA Astrophysics Data System (ADS)

The elastic scattering of deuterons, 3He and 4He on 6Li at different incident energies have been analyzed in the framework of the optical model (OM) using ECIS88 as well as SPI GENOA codes. The optical potential parameters were extracted in the phenomenological treatment. A good agreement between theoretical and experimental differential cross-sections was obtained in whole angular range. Parameters for real part of potential have been also calculated microscopically with double-folding model for the d, 3He and 4He scattering, respectively, using DFPOT code. The elastic transfer mechanism has been studied by coupled reaction channel (CRC) method using FRESCO code. Spectroscopic amplitudes of 6Li ? t + 3He and 6Li ? ? + d configurations have been extracted from d, 3He and 4He scattering on 6Li at wide energy range. A comparison between spectroscopic amplitudes obtained from deuteron and ? elastically scattering from 6Li has been made. The extracted spectroscopic amplitudes of 6Li ? 4He + d(SF = SA2) from 6Li(d, 6Li)d and 6Li(?, 6Li)? are not the same as expected theoretically.

Amar, A.

2014-07-01

257

Determination of the Azimuthal Asymmetry of Deuteron Photodisintegration in the Energy Region E{sub {gamma}} = 1.1 - 2.3 GeV  

SciTech Connect

Deuteron photodisintegration is a benchmark process for the investigation of the role of quarks and gluons in nuclei. Existing theoretical models of this process describe the available cross sections with the same degree of success. Therefore, spin-dependent observables are crucial for a better understanding of the underlying dynamical mechanisms. However, data on the induced polarization (P{sub y}), along with the polarization transfers (C{sub x'} and C{sub z'} ), have been shown to be insensitive to differences between theoretical models. On the other hand, the beam-spin asymmetry {Sigma} is predicted to have a large sensitivity and is expected to help in identifying the energy at which the transition from the hadronic to the quark-gluon picture of the deuteron takes place. Here, the work done to determine the experimental values of the beam-spin asymmetry in deuteron photodisintegration for photon energies between 1.1 ? 2.3 GeV is presented. The data were taken with the CLAS at the Thomas Jefferson National Accelerator Facility during the g13 experiment. Photons with linear polarization of ~80% were produced using the coherent bremsstrahlung facility in Hall B. The work done by the author to calibrate a specific detector system, select deuteron photodisintegration events, study the degree of photon polarization, and finally determine the azimuthal asymmetry and any systematic uncertainties associate with it, is comprehensively explained. This work shows that the collected data provide the kinematic coverage and statistics to test the available QCD-based models. The results of this study show that the available theoretical models in their current state do not adequately predict the azimuthal asymmetry in the energy region 1.1 ? 2.3 GeV.

Nicholas Zachariou

2012-05-20

258

Polarized deuterons and protons at NICA@JINR  

NASA Astrophysics Data System (ADS)

The novel scheme of proton and deuteron polarization control in the NICA collider at Dubna is proposed. By means of two Siberian Shakes with solenoid magnetic field the beam spin tune is shifted to the "zero" spin resonance vicinity, whereas manipulation of the polarization is realized by "weak" field solenoids. The scheme makes it possible to obtain any desired direction of the polarization in the both MPD and SPD detectors for any sort of the particles. The possibility of the beam polarization control in the orbit plane at any azimuth of the collider magnetic arcs exists also. The last gives necessary flexibility of optimal matching the beam polarization at injection into collider and at the polarimetery monitor points.

Kovalenko, A. D.; Filatov, Yu. N.; Kondratenko, A. M.; Kondratenko, M. A.; Mikhaylov, V. A.

2014-01-01

259

Covariant Spectator Theory of np scattering: Deuteron Quadrupole Moment  

The deuteron quadrupole moment is calculated using two CST model wave functions obtained from the 2007 high precision fits to $np$ scattering data. Included in the calculation are a new class of isoscalar $np$ interaction currents automatically generated by the nuclear force model used in these fits. The prediction for model WJC-1, with larger relativistic P-state components, is $2.5\\%$ smaller that the experiential result, in common with the inability of models prior to 2014 to predict this important quantity. However, model WJC-2, with very small P-state components, gives agreement to better than 1\\%, similar to the results obtained recently from $\\chi$EFT predictions to order N$^3$LO.

Gross, Franz

2015-01-01

260

Correcting systematic errors in high-sensitivity deuteron polarization measurements  

NASA Astrophysics Data System (ADS)

This paper reports deuteron vector and tensor beam polarization measurements taken to investigate the systematic variations due to geometric beam misalignments and high data rates. The experiments used the In-Beam Polarimeter at the KVI-Groningen and the EDDA detector at the Cooler Synchrotron COSY at Jülich. By measuring with very high statistical precision, the contributions that are second-order in the systematic errors become apparent. By calibrating the sensitivity of the polarimeter to such errors, it becomes possible to obtain information from the raw count rate values on the size of the errors and to use this information to correct the polarization measurements. During the experiment, it was possible to demonstrate that corrections were satisfactory at the level of 10 -5 for deliberately large errors. This may facilitate the real time observation of vector polarization changes smaller than 10 -6 in a search for an electric dipole moment using a storage ring.

Brantjes, N. P. M.; Dzordzhadze, V.; Gebel, R.; Gonnella, F.; Gray, F. E.; van der Hoek, D. J.; Imig, A.; Kruithof, W. L.; Lazarus, D. M.; Lehrach, A.; Lorentz, B.; Messi, R.; Moricciani, D.; Morse, W. M.; Noid, G. A.; Onderwater, C. J. G.; Özben, C. S.; Prasuhn, D.; Levi Sandri, P.; Semertzidis, Y. K.; da Silva e Silva, M.; Stephenson, E. J.; Stockhorst, H.; Venanzoni, G.; Versolato, O. O.

2012-02-01

261

Nonradiative proton--deuteron fusion in stellar plasma  

E-print Network

The nuclear reaction e+p+d -----> He3 + e is considered at thermonuclear energies. The motion of the electron is treated within the adiabatic approximation and the pd scattering state is constructed in the form of an antisymmetrized product of the bound state wave function of the deuteron and of the wave function of the pd relative motion. The latter is calculated using an effective pd potential constructed via the Marchenko inverse scattering method. The bound state wave function of He3 is obtained using Faddeev--type integrodifferential equations. The reaction rate thus obtained for the solar interior conditions is approximately 10^{-4} of the corresponding rate for the radiative capture pd ----> He3 + gamma .

S. A. Rakityansky; S. A. Sofianos; L. L. Howell; M. Braun; V. B. Belyaev

1996-07-16

262

Covariant spectator theory of n p scattering: Deuteron quadrupole moment  

NASA Astrophysics Data System (ADS)

The deuteron quadrupole moment is calculated using two covariant spectator theory model wave functions obtained from the 2007 high-precision fits to n p scattering data. Included in the calculation are a new class of isoscalar n p interaction currents automatically generated by the nuclear force model used in these fits. The prediction for model WJC-1, with larger relativistic P -state components, is 2.5 % smaller than the experimental result, in common with the inability of models prior to 2014 to predict this important quantity. However, model WJC-2, with very small P -state components, gives agreement to better than 1%, similar to the results obtained recently from chiral effective field theory predictions to next-to-next-to-next-to-leading order.

Gross, Franz

2015-01-01

263

Proton Polarization Angular Distribution in Deuteron Photo-Disintegration  

SciTech Connect

The apparent scaling in 90 cm deuteron photodisintegration, first observed several years ago at SLAC, has lead to several related experiments and a number ot theoretical calculations.We have in the past year measured in Hall A, with up to 2.5-GeV photons, cross sections at large angles and the proton polarization at 90cm.Verypreliminary online analysis of the induced polarizations yields the very surprising result that theinduced polarizations apparently vanish starting at about the same energy at whichthe existing cross section data start to scale, to follow the constituent countingrules.Given this result, we propose further measurements to see if this observationholds at other angles.

Sarty, Adam; Fox, Brendan; Meekins, David; Margaziotis, Demetrius; Kinney, Edward; Garibaldi, Franco; Gao, Juncai; Aniol, Konrad; Epstein, Martin; Amaryan, Moscov; Amaryan, Moskov; Markowitz, Pete; Bosted, Peter; Roche, Rikki; Gilman, Ronald; Frullani, Salvatore; Churchwell, Steve

1999-12-01

264

QCD Dynamics of High Energy Photodisintegration of the Deuteron  

NASA Astrophysics Data System (ADS)

The recent experiments on high energy two-body photodisintegration of the deuteron [1,2,3] set a new stage in high energy (E_? >= 1 GeV) nuclear physics. The calculations using the conventional mesonic picture of nuclear interactions failed to describe the qualitative features of these measurements. Our analysis demonstrated that at the photon energies E_?>= 2-2.5 GeV the relevant degrees of freedom in the reaction is the quarks rather then nucleons and mesons. We developed a new theoretical approach [4] in which the photon absorption by a quark in one nucleon followed by its high momentum transfer interaction with a quark in the other may produce two final-state nucleons with high relative momentum. We sum the relevant quark rescattering diagrams, to show that the scattering amplitude depends on a convolution between the large angle pn scattering amplitude, the hard photon-quark interaction vertex and the low-momentum deuteron wave function. The computed absolute values of the cross section are in reasonable agreement with the data. The further development of the present approach is the calculation of polarization observables which have been measured recently at Jefferson Lab. We will discuss the results of our calculation for these observables and give an outlook on possible extension of the studies to the domain of electro-disintegration reactions. [1] C. Bochna et al., Phys. Rev. Lett. 81, 4576 (1998). [2] S.J. Freedman et al., Phys. Rev. C48, 1864 (1993). [3] J.E. Belz et al., Phys. Rev. Lett. 74, 646 (1995). [4] L.L. Frankfurt, G.A. Miller, M.M. Sargsian and M.I. Strikman, Phys. Rev. Lett. 84, 3045 (2000).

Sargsian, Misak

2000-10-01

265

Parity violation in neutron deuteron scattering in pionless effective field theory  

NASA Astrophysics Data System (ADS)

In this dissertation the parity violating neutron deuteron scattering amplitudes are calculated using pionless effective field theory to leading order. The five low energy parity violating constants present in pionless effective field theory are estimated by matching onto the ``best" values for the parameters of the model by Desplanques, Donoghue, and Holstein (DDH). Using these estimates and the calculated amplitudes, predictions for the spin rotation of a neutron through a deuteron target are given with a value of 1.8 × 10-8 rad cm-1. Also given are the longitudinal analyzing power in neutron deuteron scattering with a polarized neutron yielding 2.2 × 10-8, and a polarized deuteron giving 4.0 × 10-8. These observables are discussed in the broader context of hadronic parity violation and as possible future experiments to determine the values of the five low energy parity violating constant present in pionless effective theory.

Vanasse, Jared J.

266

Pre-breakup age of East Greenland Ridge strata  

NASA Astrophysics Data System (ADS)

The East Greenland Ridge (EGR) is a submarine elevation that juts out from the Northeast Greenland shelf, separating the modern Boreas Basin in north from the Greenland Basin in south. The EGR strikes roughly northwest-southeast and lies almost perpendicular to the Mohns Spreading Ridge and sub-parallel to the Knipovich Spreading Ridge. The EGR is about 320 km long and includes several en-echelon elongated crests. The flanks on either side of the EGR are generally high and steep, with escarpments exposing outcropping sub-strata. The EGR has been characterized as a continental sliver. However, this is based on analysis of seismic data only, while no direct evidence has hitherto been published to strengthen this interpretation. In 2012, two up-slope transects on the northeastern lower flank of the EGR were dredged by GEUS and UiT in order to obtain in-situ samples of the outcropping strata. Subsequent work by GEUS on the dredged samples was concentrated on lithological description and age determination of selected rock samples. The selected samples were either fresh and angular, or too soft to have survived long transport, and therefore interpreted to be in-situ or near in-situ (local and limited transported) and representative for the geology of the EGR. Some rock samples of greenish grey, slightly sandy mudstones were dated by palynological analysis to be of Late Triassic (Carnian) age, i.e. to pre-date the onset of seafloor spreading in this part of the Northeast Atlantic Ocean by more than 150 ma years. Notably, no basalts were dredged, which further supports the interpretation that the strata overlying the basement of the EGR is composed of pre-breakup sediments, and thus strengthen the characterization of the EGR as a continental sliver.

Nielsen, Tove; Bjerager, Morten; Lindström, Sofie; Nøhr-Hansen, Henrik; Lander Rasmussen, Tine

2014-05-01

267

Deformation and breakup of round drops and nonturbulent liquid jets in uniform crossflows  

NASA Astrophysics Data System (ADS)

The deformation and breakup properties of liquid drops and round liquid jets in uniform crossflows were studied computationally, motivated by applications to the behavior of sprays in crossflows found in a variety of power and propulsion systems. The objective of the present investigation was to extend the parameter range of past deformation and breakup studies, by means of numerical computations, to conditions more representative of practical high-pressure spray combustion processes. The time-dependent, incompressible and two-dimensional Navier-Stokes equations were solved on a uniform, staggered grid using the projection method of Chorin (1968) and the Level Set method of Sussman et al. (1994). Numerical simulations of the effect of crossflows on the deformation and breakup of drops and round liquid jets were carried out for the following range of parameters to study the independent effects of four dimensionless variables that fully describe the problem: Weber numbers of 0.1--2,000,000, Ohnesorge numbers of 0.001--100, Reynolds numbers of 12.5--200 and liquid/gas density ratios of 2--infinity (the last by Richardson extrapolation). The present results were in good agreement with existing measurements of deformation and breakup properties of both liquid drops and round liquid jets at large liquid/gas density ratios and with wake and drag properties of spheres and cylinders in crossflows. Similar to past experimental observations, remarkable similarities were observed between the breakup properties of round liquid jets and liquid drops. The liquid/gas density ratio was found to have a relatively small effect on deformation and breakup. Effects of Reynolds number variations were also small for conditions where the drag coefficient is relatively independent of the Reynolds number. As the Stokes flow regime is approached, however, the Weber number (We) required for breakup increases significantly due to increased drag coefficients. At large Ohnesorge number (Oh) conditions, where liquid viscous forces dominate surface tension forces, breakup is best defined in terms of a critical ratio of drag forces to liquid viscous forces, We 1/2/Oh, and plotting We1/2 /Oh vs. 1/Oh yielded breakup regime boundaries that were relatively constant for large Oh and largely independent of other parameters of the flow.

Aalburg, Christian

2002-09-01

268

Spin and Parity Assignments in PHOSPHORUS-34 Using the Polarized (deuteron, Alpha) and (deuteron, Alpha Gamma) Reactions.  

NASA Astrophysics Data System (ADS)

A measurement of method II (d,alpha gamma) angular correlations (LF61), using a polarized deuteron beam is a powerful technique for determining spins and parities in light nuclei, since two separate correlations, corresponding to two beam polarization substates, are measured for each transition and in each case the residual nucleus is left in a strongly polarized state. This technique, together with model-independent parity assignments from T_{20} measurements at zero degrees, has been used to measure the spins and parities of the low-lying excited states in the nucleus ^{34}P. The resulting J ^pi assignments for these states are well reproduced by a shell model calculation using Wildenthal's used interaction (Wi82). The effect of the finite particle detector size and the less than completely polarized beam on the measured correlations has been discussed and the results have been incorporated into the final analysis.

Trudel, Anne Janine

269

Deuteron Magnetic Resonance Spectrum and Relaxation in KD2 PO4  

Microsoft Academic Search

The electric field gradient (EFG) tensor at the site of the deuteron in the hydrogen bond of KD2PO4 and the relaxation times of the deuteron have been studied. The measured quadrupole coupling constant is 119 kc\\/sec, the asymmetry parameter is 0.049, and the major principal axis of the tensor is along the bond direction. None of these features of the

John L. Bjorkstam; Edwin A. Uehling

1959-01-01

270

Deuteron magnetic resonance study of CoSiF6.6D2O  

Microsoft Academic Search

The quadrupole coupling constant, asymmetry parameter and the direction of the principal axes of the EFG tensor of deuterons in CoSiF6.6D2O have been obtained at room temperature. A temperature variation study of 2D resonance reveals an abrupt change in the quadrupolar splitting frequency and in the linewidth of the individual deuteron line at the transition temperature Tc=262+or-2K during the cooling

M. Bose; A. Ghoshray; A. Basu; K. Roy

1979-01-01

271

Assessment of the Breakup of the Antarctic Polar Vortex in Two New Chemistry-Climate Models  

NASA Technical Reports Server (NTRS)

Successful simulation of the breakup of the Antarctic polar vortex depends on the representation of tropospheric stationary waves at Southern Hemisphere middle latitudes. This paper assesses the vortex breakup in two new chemistry-climate models (CCMs). The stratospheric version of the UK Chemistry and Aerosols model is able to reproduce the observed timing of the vortex breakup. Version 2 of the Goddard Earth Observing System (GEOS V2) model is typical of CCMs in that the Antarctic polar vortex breaks up too late; at 10 hPa, the mean transition to easterlies at 60 S is delayed by 12-13 days as compared with the ERA-40 and National Centers for Environmental Prediction reanalyses. The two models' skill in simulating planetary wave driving during the October-November period accounts for differences in their simulation of the vortex breakup, with GEOS V2 unable to simulate the magnitude and tilt of geopotential height anomalies in the troposphere and thus underestimating the wave driving. In the GEOS V2 CCM the delayed breakup of the Antarctic vortex biases polar temperatures and trace gas distributions in the upper stratosphere in November and December.

Hurwitz, M. M.; Newman, P. A.; Oman, L. D.; Li, F.; Morgenstern, O.; Braesicke, P.; Pyle, J. A.

2010-01-01

272

Modern Studies of the Deuteron: from the Lab Frame to the Light Front  

E-print Network

We review the recent progress made in studies of deuteron structure at small internucleon distances. This progress is largely facilitated by the new generation of experiments in deuteron electrodisintegration carried out at unprecedentedly high momentum transfer. The theoretical analysis of these data confirms the onset of the high energy eikonal regime in the scattering process which allows one to separate long range nuclear effects from the effects genuinely related to the short distance structure of the deuteron. Our conclusion is that for the first time the deuteron is probed at relative momenta beyond 300 MeV/c without dominating long range effects. As a result, at these large nucleon momenta the cross section is sensitive to the nuclear dynamics at sub-fermi distances. Due to large internal momenta involved we are dealing with the relativistic bound state that is best described by the light-cone momentum distribution of nucleons in the deuteron. We present the first attempt of extracting the deuteron li...

Boeglin, Werner

2015-01-01

273

Effects of earlier sea ice breakup on survival and population size of polar bears in western Hudson Bay  

USGS Publications Warehouse

Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population-level effects of climatic change, however, remain difficult to quantify. We used a flexible extension of Cormack-Jolly-Seber capture-recapture models to estimate population size and survival for polar bears (Ursus maritimus), one of the most ice-dependent of Arctic marine mammals. We analyzed data for polar bears captured from 1984 to 2004 along the western coast of Hudson Bay and in the community of Churchill, Manitoba, Canada. The Western Hudson Bay polar bear population declined from 1,194 (95% CI = 1,020-1,368) in 1987 to 935 (95% CI = 794-1,076) in 2004. Total apparent survival of prime-adult polar bears (5-19 yr) was stable for females (0.93; 95% CI = 0.91-0.94) and males (0.90; 95% CI = 0.88-0.91). Survival of juvenile, subadult, and senescent-adult polar bears was correlated with spring sea ice breakup date, which was variable among years and occurred approximately 3 weeks earlier in 2004 than in 1984. We propose that this correlation provides evidence for a causal association between earlier sea ice breakup (due to climatic warming) and decreased polar bear survival. It may also explain why Churchill, like other communities along the western coast of Hudson Bay, has experienced an increase in human-polar bear interactions in recent years. Earlier sea ice breakup may have resulted in a larger number of nutritionally stressed polar bears, which are encroaching on human habitations in search of supplemental food. Because western Hudson Bay is near the southern limit of the species' range, our findings may foreshadow the demographic responses and management challenges that more northerly polar bear populations will experience if climatic warming in the Arctic continues as projected.

Regehr, E.V.; Lunn, N.J.; Amstrup, Steven C.; Stirling, I.

2007-01-01

274

A Examination of Two-Nucleon Correlations in CARBON-12 via (electron, Electron' Proton) and (electron, Electron' Deuteron) at X = 2 and Momentum Transfer = 913 Mev/c.  

NASA Astrophysics Data System (ADS)

This thesis describes the measurement of ^{12}C(e,e^' p) and ^{12}C(e,e ^'d) at the kinematics for quasielastic knockout of a deuteron with a momentum transfer of 913 MeV/c and an energy transfer of 213 MeV. We measured the coincidence cross section as a function of the missing energy over the range E_{m } = 0-210. The experiment was performed in February 1989 in the South Hall at the Bates Linear Accelerator Center. We used the Bigbite and OHIPS spectrometers to detect the scattered electrons and hadrons respectively. The beam energy was 781 MeV. The data was a challenge to analyze because of the low statistics, some faulty electronics, and the poor performance of the electron spectrometer. The problems which affected the data have been understood and corrected. The data has also been corrected for radiative effects. In the ^{12}C(e,e ^'p) cross section we can identify a narrow peak at 18 MeV associated with proton knockout from the P-shell and a region from 27-60 MeV which we attribute to knockout from the S-shell and to multinucleon reactions. The cross section above 60 MeV is consistent zero except for a small bump at E_{m } ~ 110 MeV. This tiny peak occurs at E_{m} ~ omega/2 which corresponds to the break-up of a two-nucleon pair. The cross section at this point is on the same order as the total measured cross section for deuteron knockout. We compared the P-shell and S-shell ^ {12}C(e,e^'p) cross section to a factorized DWIA calculation. We used the program PEEPSO to generate the distorted momentum distributions and the program MONTEEP to form the theoretical counts spectra. The calculated cross section greatly overestimated the data. Comparisons between theory and data for a range of experiments suggests that the theoretical momentum distributions for large negative missing momentum are in error. In the ^{12}C(e,e ^'d) cross section we can identify a narrow peak at 26 MeV which corresponds to deuteron knockout where the residual ^{10} B nucleus remains in the ground state or a low excited state. A second broad peak centered at 65 MeV is associated with deuteron knockout where one of the nucleons was in the S-shell and the other was in either the S- or the P -shell. We developed a simple kinematical model to describe the ^{12}C(e,e ^'d) cross section. The missing energy distribution and center-of-mass momentum distribution for the n-p was generated by convoluting the single particle distributions. We examined several models for the n-p relative momentum distribution. The results have a similar form to the data and indicate that the knocked-on n-p pair interact via a short range N-N potential. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.).

Penn, Steven Douglas

275

Droplet Deformation Prediction With the Droplet Deformation and Breakup Model (DDB)  

NASA Technical Reports Server (NTRS)

The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.

Vargas, Mario

2012-01-01

276

{sup 8}B proton halo via reaction and breakup cross section measurements  

SciTech Connect

The reaction cross section for {sup 8}B and {sup 7}Be and the breakup cross section for {sup 8}B on silicon have been measured for incident energies between 10 and 40 MeV/nucleon with a stack of silicon detectors. Secondary {sup 8}B and {sup 7}Be beams were obtained by use of the LISE spectrometer at GANIL. The stack of silicon detectors had the multiple purpose of slowing down the incident secondary beams, identifying the reaction products, and measuring their energy. The separate contributions of diffraction dissociation and absorption to the breakup have been determined. The parallel momentum distribution of {sup 7}Be resulting from the breakup of {sup 8}B has also been determined. The data are compared to theoretical calculations. {copyright} {ital 1996 The American Physical Society.}

Negoita, F.; Borcea, C.; Carstoiu, F. [IAP, P.O. Box MG-6, 76900 Bucharest-Magurele (Romania)] [IAP, P.O. Box MG-6, 76900 Bucharest-Magurele (Romania); Lewitowicz, M.; Saint-Laurent, M.G.; Anne, R.; Bazin, D.; Corre, J.M.; Roussel-Chomaz, P. [GANIL (IN2P3/CNRS,DSM/CEA) Boite Postale 5027, 14021 Caen Cedex (France)] [GANIL (IN2P3/CNRS,DSM/CEA) Boite Postale 5027, 14021 Caen Cedex (France); Borrel, V.; Guillemaud-Mueller, D.; Keller, H.; Mueller, A.C.; Pougheon, F.; Sorlin, O. [IPN, CNRS-IN2P3, 91406 Orsay Cedex (France)] [IPN, CNRS-IN2P3, 91406 Orsay Cedex (France); Lukyanov, S.; Penionzhkevich, Y.; Fomichev, A.; Skobelev, N.; Tarasov, O. [FLNR, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russia)] [FLNR, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russia); Dlouhy, Z. [NPI, 250 68 Rez (Czech Republic)] [NPI, 250 68 Rez (Czech Republic); Kordyasz, A. [Institute of Experimental Physics, Warsaw University, Hoza 69, 00681 Warsaw (Poland)] [Institute of Experimental Physics, Warsaw University, Hoza 69, 00681 Warsaw (Poland)

1996-10-01

277

Imaging and photometry of comet C/1999 S4 (LINEAR) before perihelion and after breakup.  

PubMed

We analyzed photometric measurements and images of comet C/LINEAR before perihelion and after its breakup. Results from our photometry data include a lower limit of 0.44 kilometer for the radius of the nucleus before breakup, and a determination that it was depleted in carbon-chain molecules relative to most other comets. Our imaging and modeling results, which include a constraint on the rotational state of the nucleus, indicate that the disintegration likely started on 18 or 19 July 2000. The total mass detectable in the dust tail after the breakup was 3 x 10(8) kilograms, comparable to one of the fragments in the Hubble Space Telescope images; we therefore infer that most of the comet's original mass is hidden in remnants between 1 millimeter and 50 meters in diameter. PMID:11359005

Farnham, T L; Schleicher, D G; Woodney, L M; Birch, P V; Eberhardy, C A; Levy, L

2001-05-18

278

Droplet formation from the breakup of micron-sized liquid jets  

NASA Astrophysics Data System (ADS)

Droplet formation from the breakup of a liquid jet emerging from a micron-sized circular nozzle is investigated with ultra high-speed imaging at 1 million frames per second and within a lubrication approximation model [Eggers and Dupont, Phys. Rev. Lett. 262, 1994, 205-221]. The capillary time ?c= ??r^3 / ? is extremely small -- of the order of 1?s. In the analyzed low Reynolds number regime the jet breakup is driven by surface tension forces only. Rayleigh breakup is not influenced by the surrounding air. The high- speed imaging results and those from the model calculation perfectly agree for various liquid viscosities and jet velocities, confirming a universal scaling law also for diminutive Rayleigh jets.

van Hoeve, Wim; van der Bos, Arjan; Versluis, Michel; Snoeijer, Jacco; Brenner, Michael P.; Lohse, Detlef

2009-11-01

279

Deuteron energy of 15 MK in ultra-dense deuterium without plasma formation: Temperature of the interior of the Sun  

Microsoft Academic Search

Deuterons are released with kinetic energy up to 630 eV from ultra-dense deuterium as shown previously, by Coulomb explosions initiated by ns laser pulses at ?1011 Wcm?2. With higher laser intensity at 1014 Wcm?2, the initial kinetic energy now observed by TOF-MS with variable acceleration energy is up to 1100 eV per deuteron. This indicates ejection of one deuteron by

Patrik U. Andersson; Leif Holmlid

2010-01-01

280

Complete Set of Deuteron Analyzing Powers for dp Elastic Scattering at 250 MeV\\/nucleon and Three Nucleon Forces  

Microsoft Academic Search

Measurements of a complete set of deuteron analyzing powers (iT11, T20, T21, T22) for elastic deuteron-proton scattering at 250 MeV\\/nucleon have been performed with polarized deuteron beams at RIKEN RI Beam Factory. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with the Tucson-Melbourne'99, and UrbanaIX three nucleon forces.

K. Sekiguchi; N. Sakamoto; M. Sasano; S. Sakaguchi; H. Okamura; H. Suzuki; H. Sakai; K. Yako; Y. Shimizu; Y. Maeda; T. Saito; T. Wakasa; M. Dozono

2010-01-01

281

Complete Set of Deuteron Analyzing Powers for dp Elastic Scattering at Intermediate Energies and Three Nucleon Forces  

NASA Astrophysics Data System (ADS)

Experimental programs with polarized deuterons beams at intermediate energies are in progress at RIKEN RI Beam Factory. We have measured a complete set of deuteron analyzing powers in deuteron-proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with the Tucson-Melbourne'99, and UrbanaIX three nucleon forces.

Sekiguchi, K.; Okamura, H.; Wada, Y.; Miyazaki, J.; Taguchi, T.; Gebauer, U.; Dozono, M.; Kawase, S.; Kubota, Y.; Lee, C. S.; Maeda, Y.; Mashiko, T.; Miki, K.; Sakaguchi, S.; Sakai, H.; Sakamoto, N.; Sasano, M.; Shimizu, Y.; Takahashi, K.; Tang, R.; Uesaka, T.; Wakasa, T.; Yako, K.

2014-03-01

282

Polarization effects in $e^+ +e^-\\to \\bar d+d$ and determination of time like deuteron form factors  

E-print Network

Polarization effects in the reaction $e^++e^-\\to \\bar d+d$ have been investigated for the case of longitudinally polarized electron beam and arbitrary polarization of the produced deuteron, with the aim of a determination of the time-like complex deuteron electromagnetic form factors. General expressions of polarization observables are derived and numerical estimations have been carried out by means of various models of deuteron electromagnetic form factors, for kinematical conditions near threshold.

G. I. Gakh; E. Tomasi--Gustafsson; C. Adamuš?ín; S. Dubni\\v cka; A. Z. Dubni?kov\\' a

2006-04-25

283

Bag breakup of low viscosity drops in the presence of a continuous air jet  

NASA Astrophysics Data System (ADS)

This work examines the breakup of a single drop of various low viscosity fluids as it deforms in the presence of continuous horizontal air jet. Such a fragmentation typically occurs after the bulk liquid has disintegrated upon exiting the atomizer and is in the form of an ensemble of drops which undergo further breakup. The drop deformation and its eventual disintegration is important in evaluating the efficacy of a particular industrial process, be it combustion in automobile engines or pesticide spraying in agricultural applications. The interplay between competing influences of surface tension and aerodynamic disruptive forces is represented by the Weber number, We, and Ohnesorge number, Oh, and used to describe the breakup morphology. The breakup pattern considered in our study corresponds to that of a bag attached to a toroidal ring which occurs from ˜12 < We < ˜16. We aim to address several issues connected with this breakup process and their dependence on We and Oh which have been hitherto unexplored. The We boundary at which breakup begins is theoretically determined and the expression obtained, We = 12( {1 + 2/3 Oh^2 } ), is found to match well with experimental data {[L.-P. Hsiang and G. M. Faeth, Int. J. Multiphase Flow 21(4), 545-560 (1995)] and [R. S. Brodkey, "Formation of drops and bubbles," in The Phenomena of Fluid Motions (Addison-Wesley, Reading, 1967)]}. An exponential growth in the radial extent of the deformed drop and the streamline dimension of the bag is predicted by a theoretical model and confirmed by experimental findings. These quantities are observed to strongly depend on We. However, their dependence on Oh is weak.

Kulkarni, V.; Sojka, P. E.

2014-07-01

284

Under-ice movement of cohesive sediments before river-ice breakup  

NASA Astrophysics Data System (ADS)

A significant body of research exists on river hydraulics and sediment transport during open-water conditions, and to a lesser extent during the period of ice-cover. Most of the ice-related studies, however, are based on controlled laboratory experiments or field studies conducted under stable ice-cover conditions. They have largely ignored the most dynamic periods, such as breakup, when hydraulic conditions are most rapidly changing and energy levels are maximized. Moreover, the entire pre-breakup to ice-clearance period is virtually devoid of even standard hydrometric measurements of suspended sediment, largely because of safety and logistic problems. Some recent work has pointed to the formation of a sediment plume comprising fine-grained sediments that develops before the main breakup fracturing of the ice cover. This plume has been noted as being particularly ecologically significant because it can contain the winter-long deposition of contaminants that preferentially attach to fine-grained material. Unfortunately, however, because measurements of the critical parameters affecting sediment transport during these periods are rarely taken, much uncertainty remains about the hydraulic forces that resuspend and transport sediments under an ice cover, and particularly for cohesive fine-grained sediments. This paper describes a field experiment designed to broaden our understanding of sediment transport during this critical pre-breakup period. Detailed measurements of river stage, ice elevations, flow velocity profiles and suspended sediment were taken over a 17-day period just before the 1998 river-ice breakup at Hay River, Northwest Territories, Canada. Results indicated that just before breakup, the shear stress, which governs the beginning of sediment motion, increases dramatically and drives the development of the under-ice sediment plume of very fine-grained, cohesive sediments. The shear stress in this case became critical at a mean under-ice velocity of 0·4 m/s.

Milburn, D.; Prowse, T. D.

2002-03-01

285

Determination of the threshold of the break-up of invariant tori in a class of three frequency Hamiltonian systems  

E-print Network

Determination of the threshold of the break-up of invariant tori in a class of three frequency Hamiltonian systems C. Chandre Service de Physique Th#19;eorique, CEA Saclay, F-91191 Gif-sur-Yvette cedex of this paper is to determine the threshold of the break-up of an invariant torus with a speci#12;c frequency

Roma Tor Vergata, Università di

286

Post-breakup tectonics in southeast Brazil from thermochronological data and combined inverse-forward thermal history modeling  

E-print Network

with Andean tectonics and those in NE Brazil leads us to assume a plate-wide compressional stressPost-breakup tectonics in southeast Brazil from thermochronological data and combined inverse. Riccomini, and C. Gautheron (2012), Post-breakup tectonics in southeast Brazil from thermochronological data

Paris-Sud XI, Université de

287

Study of the effects of nuclear and Coulomb interactions in the breakup of 19C on 208Pb  

NASA Astrophysics Data System (ADS)

A detailed partial wave analysis of the breakup of 19C on 208Pb at 67 MeV/A is performed to investigate the effects of the nuclear and Coulomb breakups. It is first shown that the breakup cross sections are dominated by p-waves, but all the outgoing neutrons are not necessarily in the p-waves. The contributions of the other partial waves are important and account for the normalization of the breakup cross section. The nuclear contribution is not negligible for angles below 3{}^\\circ and in fact both nuclear and Coulomb breakups contribute equally between 2{}^\\circ and 3{}^\\circ . The incoherent difference of the full (coherent sum of nuclear and Coulomb breakups) and nuclear breakup cross sections agree with the data for low excitation energies. However, the full breakup cross section alone describes well the data for high excitation energies. We found that the small nuclear contribution does not directly imply small nuclear–Coulomb interferences, which was generally found to be destructive regardless whether the continuum–continuum couplings are included or not.

Mukeru, B.; Lekala, M. L.; Denikin, A. S.

2015-01-01

288

Beltaos S. and Kb A. (2013): Estimating river discharge during ice breakup from near-simultaneous satellite imagery  

E-print Network

-economic and ecological implications that primarily result from the formation and release of major ice jams. A key driver, results of ice jamming that accompanies dynamic breakup events. Less well known, but just as important, and degradation of water quality (Beltaos, 2007). Breakup ice jamming can also be beneficial, however. For example

Kääb, Andreas

289

Effects of thermal quenching on the breakup of pyroclasts  

NASA Astrophysics Data System (ADS)

It is often assumed that magma fragments when it contacts water. Obsidian chips and glass spheres crack when quenched. Vesicular pyroclasts are made of similar glass, so thermal quenching may cause them to break more easily. We performed a set of experiments on air fall pumice from Medicine Lake, California. Density and texture of similar samples are described in Manga et al., Bull Volc 2010. We made "quenched" samples by heating natural pyroclasts to 600 °C, quenching them in water at 21 °C, drying them at 105 °C, and then cooling them to room temperature. We compare these samples with untreated air fall pumice from the same deposit, hereafter referred to as "regular" pumice. We tested whether quenched pumice would 1) shatter more easily in collisions and 2) abrade faster. Our collision experiment methods are described in Dufek et al., Nature Geoscience 2012. Our abrasion experiment methods are described in Manga et al., Bull Volc 2010. We also tested whether individual clasts lose mass upon quenching and whether they increase in effective wet density. Effective wet density is defined as underwater density of a clast when water occupies part of the pore space. Effective wet density, measured as a function of time after immersion, indicates the volume fraction of the pore space that becomes occupied by water. We compare effective wet density of individual clasts pre-quenching with effective wet density after having been quenched, thoroughly dried and then cooled to room temperature. An increase in effective wet density would suggest that bubble walls had been damaged during quenching, allowing water to occupy the pore space faster. We also compare pre-quenching and post-quenching textures using X-Ray Tomography (XRT) and SEM images. Results from collision experiments show no obvious difference between quenched pumice and regular pumice. Quenched pumice abraded more quickly than regular pumice. We find that 1 to 2 % of mass was lost during quenching. Effective wet density increased 0 to 2.5 %, as measured after 5 minutes immersion in water. Overall we see modest differences between quenched pumice and regular pumice in breakup, abrasion, mass, and effective wet density. Experimental results suggest that quenching may damage small parts of a clast but tends not to cause cracks that propagate easily through the clast. XRT and SEM imaging confirms that quenching only damages small external parts. This is in stark contrast to non-vesicular glass that develops large cracks on quenching.

Patel, A.; Manga, M.; Carey, R. J.; Degruyter, W.; Dufek, J.

2012-12-01

290

Expressions for the threshold current of multipass beam breakup in recirculating linacs from single cavity models  

SciTech Connect

We investigate multipass beam breakup (BBU) in a recirculating linear accelerator in the framework of a single cavity model. We present expressions for the beam breakup threshold current for various situations derived from a perturbative solution of BBU equations. These formulae should serve as a guide to understand the BBU phenomenon for a particular system and also as a tool to estimate the BBU threshold current quickly. Many of the results presented are more general than previous considerations because they include the effects of coupling between the two transverse polarizations in each dipole higher order mode.

Byung C. Yunn

2005-10-01

291

Break-up phenomena of liquid metal thin film induced by high electric current  

E-print Network

The room temperature liquid metal related electronics has been found important in a wide variety of emerging areas over the past few years. However, its failure features under high electrical current densities are not clear until now. Here we show that a liquid metal thin film would break-up as the applied current increases to a critical magnitude. The break-up phenomenon is attributed to be caused by the so-called electromigration effect. This problem could be one of the major hurdles that must be tackled with caution in the research and application of future liquid metal film electronics.

Rongchao Ma; Cangran Guo; Yixin Zhou; Jing Liu

2013-09-03

292

On the breakup of air bubbles in Hele-Shaw cell  

E-print Network

We study the problem of breakup of an air bubble in a Hele-Shaw cell. In particular, we propose some sufficient conditions of breakup of the bubble, and ways to find the contraction points of its parts. We also study regulated contraction of a pair of bubbles (in which the rates of air extraction from the bubbles is controlled), and study various asymptotic questions (such as the asymptotics of contraction of a bubble to a degenerate critical point, and asymptotics of contraction of a small bubble in presence of a big bubble).

Vladimir Entov; Pavel Etingof

2008-04-30

293

Relativistic nuclear corrections to the spin structure function of the deuteron in the light-cone variables  

SciTech Connect

The relativistic deuteron has been considered in the light-cone formalism as a system of two strongly interacting nucleons (two-nucleon approximation). The technique for the calculation of the average helicity of the proton in the deuteron has been considered in the light-cone variables. A receipt has been pro-posed for the consistent calculation of relativistic nuclear corrections to the average helicity of the proton in the deuteron and to the spin structure function of the deuteron g{sub 1}{sup D}. Relativistic-correction-induced change in the Bjorken sum rule has been discussed.

Pavlov, F. F., E-mail: f.pavlov@tuexph.stu.neva.ru [St. Petersburg State Polytechnic University (Russian Federation)

2012-06-15

294

Effects of various lithospheric yield stresses and different mantle-heating modes on the breakup of the Pangea supercontinent  

NASA Astrophysics Data System (ADS)

simulations of three-dimensional spherical mantle convection were performed to investigate the effects of various lithospheric yield stresses and two different mantle-heating modes (i.e., mixed heating from the bottom and interior and purely internal heating) on the breakup of the Pangea supercontinent and the subsequent continental drift for the past 200 Myr. Results show that the continental breakup and subsequent continental drift are accomplished in mantle convection models with two different heating modes. This implies that active upwelling plumes from the core-mantle boundary are not necessarily required for the breakup of Pangea. In addition, I found that the continental breakup is only realized when choosing a moderate value of the yield stress (~120 MPa). The bound on the yield stress derived in the present study will potentially enable the self-consistent reconstruction of continental breakup and drift as well as the accompanying pattern on mantle convection since 200 Ma.

Yoshida, Masaki

2014-05-01

295

The proton–deuteron system in pionless EFT revisited  

NASA Astrophysics Data System (ADS)

We provide a detailed discussion of the low-energy proton–deuteron system in pionless effective field theory, considering both the spin-quartet and doublet S-wave channels. Extending and amending our previous work on the subject, we calculate the 3He–3H binding energy difference both perturbatively (using properly normalized trinucleon wave functions) and non-perturbatively by resumming all O(? ) Coulomb diagrams in the doublet channel. Our nonperturbative result agrees well with a calculation that involves the full off-shell Coulomb T-matrix. Carefully examining the cutoff-dependence in the doublet channel, we present numerical evidence for a new three-nucleon counterterm being necessary at next-to-leading order if Coulomb effects are included. Indeed, such a term has recently been identified analytically. We furthermore make a case for a simplified Coulomb power counting that is consistent throughout the bound-state and scattering regimes. Finally, using a ‘partially screened’ full off-shell Coulomb T-matrix, we investigate the importance of higher-order Coulomb corrections in low-energy quartet-channel scattering.

König, Sebastian; Grießhammer, Harald W.; Hammer, H.-W.

2015-04-01

296

Muon induced deuteron disintegration in three-dimensions  

NASA Astrophysics Data System (ADS)

We present a three-dimensional (3D) description of muon induced deuteron disintegration. This reaction is treated as the decay of the muonic atom with the muon initially on the lowest K shell. Our aim is to calculate the total and differential decay rates. We work in momentum space and use 3D momentum eigenstates directly. This approach allowed us to calculate the appropriate nuclear matrix elements, necessary building blocks for the differential decay rate, in a single step. For contrast - in classical calculations many partial-waves have to be taken into account. We achieved a very good agreement between the 3D and partial-wave methods for calculations that involve single-nucleon currents. Our result for the total decay rate is also in agreement with experimental values, though these are not very precise. This success motivates us to also include two-nucleon current contributions that include the meson exchange currents. Additionally, our formalism can also be applied to other, so far poorly described, processes like: ? +3 He? ? + n + d or ? +3 He ? ? + n + n + p.

Topolnicki, Kacper; Golak, Jacek; Skibi?ski, Roman; Marcucci, Laura Elisa; Wita?a, Henryk; Eldeen Elmeshneb, Alaa

2014-11-01

297

Asymptotic normalization coefficients and spectroscopic factors from deuteron stripping reactions  

NASA Astrophysics Data System (ADS)

We present the analysis of three deuteron stripping reactions, C14(d,p)C15,Ni58(d,p)Ni59, and Sn116(d,p)Sn117 using the combined method [A. M. Mukhamedzhanov and F. M. Nunes, Phys. Rev. C 72, 017602 (2005), 10.1103/PhysRevC.72.017602], in which each reaction is analyzed at low and significantly higher energies. At low energies all these reactions are peripheral and the experimental asymptotic normalization coefficients (ANCs) are determined with accuracy about 10%. At higher energies we determine the spectroscopic factors (SFs) by fixing the normalization of the peripheral parts of the reaction amplitudes governed by the ANCs found from the low-energy data. The combined method imposes a strict limitation on the variation of the geometrical parameters of the single-particle potential, which can be arbitrarily taken in the standard approach. By checking the compatibility of the ANCs and SFs using the combined method we reveal the flaw in the contemporary nuclear reaction theory in treating the nuclear interior, which is the most crucial part in the determination of the SFs.

Pang, D. Y.; Mukhamedzhanov, A. M.

2014-10-01

298

Glassy dynamics of protein methyl groups revealed by deuteron NMR.  

PubMed

We investigated site-specific dynamics of key methyl groups in the hydrophobic core of chicken villin headpiece subdomain (HP36) over the temperature range between 298 and 140 K using deuteron solid-state NMR longitudinal relaxation measurements. The relaxation of the longitudinal magnetization is weakly nonexponential (glassy) at high temperatures and exhibits a stronger degree of nonexponentiality below about 175 K. In addition, the characteristic relaxation times deviate from the simple Arrhenius law. We interpret this behavior via the existence of distribution of activation energy barriers for the three-site methyl jumps, which originates from somewhat different methyl environments within the local energy landscape. The width of the distribution of the activation barriers for methyl jumps is rather significant, about 1.4 kJ/mol. Our experimental results and modeling allow for the description of the apparent change at about 175 K without invoking a specific transition temperature. For most residues in the core, the relaxation behavior at high temperatures points to the existence of conformational exchange between the substates of the landscape, and our model takes into account the kinetics of this process. The observed dynamics are the same for dry and hydrated protein. We also looked at the effect of F58L mutation inside the hydrophobic core on the dynamics of one of the residues and observed a significant increase in its conformational exchange rate constant at high temperatures. PMID:23301823

Vugmeyster, Liliya; Ostrovsky, Dmitry; Penland, Kirsten; Hoatson, Gina L; Vold, Robert L

2013-01-31

299

Field and experimental constraints on the deformation and break-up up of injected magma (Invited)  

NASA Astrophysics Data System (ADS)

Understanding the mechanics that control mafic schlieren and enclave formation is a central issue in volcanology for interpreting the conditions of the unerupted material in a chamber. Field observations from the Tuolumne Intrusive Suite (TIS), USA, demonstrate that meter-scale migrating tubes, or “ladder dikes,” can be strongly deformed by shearing motions in the magma chamber. These delicate features offer preserved length scales of deformation that can be used to infer fundamental quantities controlling the rheology of silicic magma. Here we investigate what governs the dynamics of these tube-like structures in a shear flow using analog experiments, which are motivated by field observations from the TIS. Using variations in yield strength of the injected material, buoyancy, and ambient flow behavior, we aim to characterize the deformation of the tubes under a wide range of conditions. The experiments are conducted in an 8 cm high and 60 cm wide cylindrical tank. In all experiments the tank is filled to a depth of 7 cm with corn syrup (? = 1430 kg/m3, µ = 280 Pa s). A rigid rotating plate is driven from above by an external motor creating a simple shear flow in the corn syrup with rotation speeds varying between 0.08 - 12 rpm. The experiment involves a downward injection of a controlled volume of a particle-fluid mixture. The fluid is the same corn syrup used for the ambient fluid and the particles are glass powder (? = 2600 kg/m3, d = 1µm) and zirconium silicate spheres (? = 3600 kg/m3, d=0.4mm). Our results show that the particle-fluid tube may follow two end-member regimes depending on the shear stress/buoyancy force ratio (V*) and the viscous stress/yield stress ratio (R) imposed initially. At low R values (< 1) and low V* values (<100) as well as all R values for V* > 100, the injected tube becomes gravitationally unstable and breaks up into blobs separated by thin strands of interstitial tube material. At high R values (> 1) and low V* values (<100), the injected tube is too stiff and does not go unstable or breakup. Initial field observations of migrating tubes (Paterson 2009) in the TIS suggest that the break-up of these features can be linked to the yield strength of the magma during deformation. Here, we present a field investigation that includes detailed mapping of ~100 migrating tubes in the Cathedral Peak Granite (along with some tubes in the Half Dome granite). Preliminary results suggest that a few long tubes appear to have been broken up into regularly spaced sections. Interestingly, the majority of the mapped tubes (specifically where they occur in large clusters) are located near a contact with either host rock or another intrusive unit in the TIS and are oriented roughly perpendicular to that contact. The preserved length scales of deformation are compared to experimental regimes in which tubes break up into blobs.

Hodge, K. F.; Carazzo, G.; Jellinek, M.

2010-12-01

300

Relative Timing of CAMP, Rifting, Continental Breakup, and Basin Inversion: Tectonic Significance  

E-print Network

1 Relative Timing of CAMP, Rifting, Continental Breakup, and Basin Inversion: Tectonic Significance in eastern North America provides a temporal benchmark for assessing the relative timing of rifting, drift, and geochronological data favor a diachronous rift-drift transition (seafloor spreading began earlier in the south

301

Application of the complex scaling method for few-body scattering problems including the breakup  

NASA Astrophysics Data System (ADS)

A formalism based on the complex-scaling method is used to solve a few-particle scattering problem in configuration space. This method allows to use trivial boundary conditions and is compatible with most of the bound state techniques. In this contribution calculations of neutron scattering on triton is presented using realistic nuclear Hamiltonians for neutron energies above four-nucleon breakup threshold.

Lazauskas, Rimantas

2014-12-01

302

Early break-up of the Norwegian Channel Ice Stream during the Last Glacial Maximum  

E-print Network

the timing of ice sheet retreat as we suspect the 3 oldest ages have some inheritance from a previous ice suggest that the ice stream broke up about 2000 years earlier than the age assignment based on 14 C agesEarly break-up of the Norwegian Channel Ice Stream during the Last Glacial Maximum John Inge

Briner, Jason P.

303

Bouncing Back from a Breakup: Attachment, Time Perspective, Mental Health, and Romantic Loss  

ERIC Educational Resources Information Center

Coping with a romantic breakup is a normal developmental task of emerging adulthood. Because of their role in influencing interpersonal relationships and adjustment, attachment history and time perspectives may influence resilience to romantic loss. In an online survey of 1,404 university students ages 18-25 who reported experiencing recent…

Gilbert, Steven P.; Sifers, Sarah K.

2011-01-01

304

Effect of inertia on drop breakup under shear Yuriko Y. Renardya)  

E-print Network

numbers in the range 0 to 0.43 yield steady states with egg-shaped drops. On the other hand, the additionARTICLES Effect of inertia on drop breakup under shear Yuriko Y. Renardya) Department A spherical drop, placed in a second liquid of the same density and viscosity, is subjected to shear between

305

Triassic alkaline magmatism of the Hawasina Nappes: post-breakup melting of the Oman lithospheric mantle  

E-print Network

Triassic alkaline magmatism of the Hawasina Nappes: post-breakup melting of the Oman lithospheric within three tectonostratigraphic groups of the Hawasina Nappes in the Oman Mountains the Oman lithospheric mantle, the original DMM-HIMU signature of which was overprinted during its pervasive

Paris-Sud XI, Université de

306

DebriSat - A Planned Laboratory-Based Satellite Impact Experiment for Breakup Fragment Characterizations  

NASA Technical Reports Server (NTRS)

The goal of the DebriSat project is to characterize fragments generated by a hypervelocity collision involving a modern satellite in low Earth orbit (LEO). The DebriSat project will update and expand upon the information obtained in the 1992 Satellite Orbital Debris Characterization Impact Test (SOCIT), which characterized the breakup of a 1960 s US Navy Transit satellite. There are three phases to this project: the design and fabrication of DebriSat - an engineering model representing a modern, 60-cm/50-kg class LEO satellite; conduction of a laboratory-based hypervelocity impact to catastrophically break up the satellite; and characterization of the properties of breakup fragments down to 2 mm in size. The data obtained, including fragment size, area-to-mass ratio, density, shape, material composition, optical properties, and radar cross-section distributions, will be used to supplement the DoD s and NASA s satellite breakup models to better describe the breakup outcome of a modern satellite.

Liou, Jer-Chyi; Clark, S.; Fitz-Coy, N.; Huynh, T.; Opiela, J.; Polk, M.; Roebuck, B.; Rushing, R.; Sorge, M.; Werremeyer, M.

2013-01-01

307

Satellites in the inviscid breakup of bubbles J.M. Gordillo  

E-print Network

Satellites in the inviscid breakup of bubbles J.M. Gordillo Departamento de Ingenier the gas to liquid density ratio = g/l is different from zero, tiny satellite bubbles may be formed with a closed expression for the characteristic satellite diameter, which decreases when decreasing and which

Fontelos, Marco

308

Characterization of the 2012-044c Briz-M Upper Stage Breakup  

NASA Technical Reports Server (NTRS)

On 6 August, 2012, Russia launched two commercial satellites aboard a Proton rocket, and attempted to place them in geosynchronous orbit using a Briz-M upper stage (2012-044C, SSN 38746). Unfortunately, the upper stage failed early in its burn and was left stranded in an elliptical orbit with a perigee in low Earth orbit (LEO). Because the stage failed with much of its fuel on board, it was deemed a significant breakup risk. These fears were confirmed when it broke up 16 October, creating a large cloud of debris with perigees below that of the International Space Station. The debris cloud was tracked by the US Space Surveillance Network (SSN), which can reliably detect and track objects down to about 10 cm in size. Because of the unusual geometry of the breakup, there was an opportunity for NASA Orbital Debris Program Office to request radar assets to characterize the extent of the debris cloud in sizes smaller than the standard debris tracked by the SSN. This paper will describe the observation campaign to measure the small particle distributions of this cloud, and presents the results of the analysis of the data. We shall compare the data to the modelled size distribution, number, and shape of the cloud, and what implications this may have for future breakup debris models. We shall conclude the paper with a discussion how this measurement process can be improved for future breakups.

Matney, M. J.; Hamilton, Joseph; Papanyan, Valen

2013-01-01

309

Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures  

SciTech Connect

A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.

Schoessow, P.; Kanareykin, A.; Jing, C. [Euclid Techlabs LLC, Solon, OH 44139 (United States); Kustov, A. [Dynamics Software, Helsinki (Finland); Altmark, A. [Electrotechnical University Eltech 'LETI', St. Petersburg (Russian Federation); Gai, W. [Argonne National Laboratory, Argonne IL 60439 (United States)

2010-11-04

310

An Analysis of Recent Major Breakups in he Low Earth Orbit Region  

NASA Technical Reports Server (NTRS)

Of the 190 known satellite breakups between 1961 and 2006, only one generated more than 500 cataloged fragments. The event was the explosion of the Pegasus Hydrazine Auxiliary Propulsion System in 1996, adding 713 fragments to the U.S. Satellite Catalog. Since the beginning of 2007; however, the near-Earth environment has been subjected to several major breakups, including the Fengyun-1C anti-satellite test and the explosion of Briz-M in 2007, the unusual breakup of Cosmos 2421 in 2008, and the collision between Iridium 33 and Cosmos 2251 in 2009. Combined, these events added more than 5000 large (> or equal 10 cm) fragments to the environment. Detailed analysis of the radar cross section measurements and orbit histories of the fragments from these major events reveals several unusual characteristics in their size and area-to-mass ratio distributions. The characteristics could be related to the material composition of the parent vehicles, the nature of the breakup, and the composition and physical property of the fragments. In addition, the majority of these fragments are expected to remain in orbit for at least decades. Their long-term impact to the environment is analyzed using the NASA orbital debris evolutionary model, LEGEND. Descriptions of these analyses and a summary are included in this paper.

Liou, Jer-Chyi; Anz-Meador, P. D.

2010-01-01

311

Assembly, configuration, and break-up history of Rodinia: A synthesis  

Microsoft Academic Search

This paper presents a brief synthesis of the current state of knowledge on the formation and break-up of the early-Neoproterozoic supercontinent Rodinia, and the subsequent assembly of Gondwanaland. Our discussions are based on both palaeomagnetic constraints and on geological correlations of basement provinces, orogenic histories, sedimentary provenance, the development of continental rifts and passive margins, and the record of mantle

Z. X. Li; S. V. Bogdanova; A. S. Collins; A. Davidson; B. De Waele; R. E. Ernst; I. C. W. Fitzsimons; R. A. Fuck; D. P. Gladkochub; J. Jacobs; K. E. Karlstrom; S. Lu; L. M. Natapov; V. Pease; S. A. Pisarevsky; K. Thrane; V. Vernikovsky

2008-01-01

312

Spray angle and breakup length of charge-injected electrostatic pressure-swirl nozzle  

Microsoft Academic Search

An investigation for spray characteristics such as liquid breakup length and spray cone angle of a charge-injected electrostatic pressure-swirl nozzle has been conducted. The work forms part of the design and development of electrospray nozzle for practical oil burner application. The designed nozzle used in the experiment consists of a sharp pointed tungsten wire as a charge injector and the

G. N. Laryea; S. Y. No

2004-01-01

313

Real-Time Characterization of Formation and Breakup of Iridium Clusters in Highly Dealuminated Zeolite Y  

SciTech Connect

The chemistry of formation of iridium clusters from mononuclear iridium diethylene complexes anchored in dealuminated Y zeolite, and their subsequent breakup -- all including changes in the metal-metal, metal-support, and metal-ligand interactions -- is demonstrated by time-resolved EXAFS, XANES, and IR spectroscopy.

Uzun, Alper; Gates, Bruce C. (UCD)

2009-01-15

314

Effect of interior surface finish on the break-up of commercial shaped charge liners  

SciTech Connect

A series of experiments aimed at understanding the influence of the liner interior surface finish on the break-up of shaped charge jets has been completed. The experiments used a standard 81-mm shaped charge design, loaded with LX-14 high explosive; incorporating high-precision copper shaped charged liners. The results indicate that a significant reduction of jet break-up time occurs between a surface finish of 99.30 microinches and 375.65 microinches. Surface finishes of 4.78, 44.54 and 99.30 microinches produced significantly better ductility and associated break-up times than the 375.65-microinch finish. The baseline production process high-precision liners were measured to have an average surface finish of 44.54 microinches. The results show that for the shaped charge warhead geometry and explosive combination investigated, some care must be taken in respect to surface finish, but that very fine surface finishes do not significantly improve the jet ductility and associated break-up times.

Baker, E L; Schwartz, A J

1999-08-11

315

Note on the breakup of immersed threads in the absence of viscosity differences  

E-print Network

1 Note on the breakup of immersed threads in the absence of viscosity differences By A. Y. G U N case of threads and fluid having equal viscosities. Due to surface tension, the threads will break up. The instability of the system is expressed in terms of the so-called growth rate. Thanks to the equal viscosities

Eindhoven, Technische Universiteit

316

Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight and concentration  

E-print Network

Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight fluids all exhibit the same global necking behavior that is observed for a Newtonian fluid of equivalent, as would occur in the equivalent Newtonian fluid. Alternatively, a cylindrical filament forms in which

317

Paleoproterozoic intracratonic basin processes, from breakup of Kenorland to assembly of Laurentia: Hurwitz Basin, Nunavut, Canada  

Microsoft Academic Search

The evolution of Hurwitz Basin records discontinuous tectonic processes in the Hearne domain (northern Canada) resulting from changing distant boundary conditions. Magmatic, eustatic and paleoclimatic influences, although significant, are considered to have been of secondary importance. In agreement with recent models, lower Hurwitz Group units record intracratonic basin formation during initial breakup stages of a speculative Neoarchean supercontinent (Kenorland). In

Lawrence B Aspler; Ira E Wisotzek; Jeffrey R Chiarenzelli; Miklos F Losonczy; Brian L Cousens; Vicki J McNicoll; William J Davis

2001-01-01

318

Catastrophic ice shelf breakup as the source of Heinrich event icebergs  

E-print Network

Catastrophic ice shelf breakup as the source of Heinrich event icebergs Christina L. Hulbe,1 of the glacial North Atlantic record abrupt widespread iceberg rafting of detrital carbonate and other lithic (climate) forcings have been proposed. Here we suggest an explanation for the iceberg release

Boyce, C. Kevin

319

ICESat profiles of tabular iceberg margins and iceberg breakup at low Ted Scambos,1  

E-print Network

ICESat profiles of tabular iceberg margins and iceberg breakup at low latitudes Ted Scambos,1 Olga of tabular iceberg margins and the Ronne Ice Shelf edge reveal shapes indicative of two types of bending forces. Icebergs and shelf fronts in sea-ice-covered areas have broad ($1000 m wide), rounded, $0.6 m

Boyce, C. Kevin

320

JET BREAKUP and SPRAY FORMATION in a DIESEL ENGINE James Glimm  

E-print Network

JET BREAKUP and SPRAY FORMATION in a DIESEL ENGINE James Glimm Department of Applied Mathematics of a fuel eÃ?cient, nonpollut- ing diesel engine. We report preliminary progress on the numerical simulation Introduction The design of a fuel eÃ?cient, nonpolluting diesel engine is the subject of intensive international

New York at Stoney Brook, State University of

321

Post-breakup Basin Evolution along the South-Atlantic Margins  

NASA Astrophysics Data System (ADS)

The post-breakup tectono-stratigraphic evolution of large offshore basins along the South American and African continental margins record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. A regional comparison based on tectonic-stratigraphic analysis of selected seismic transects between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin) provides a comprehensive basin-to-basin documentation of the key geological parameters controlling ocean and continental margin development. This comparison includes the margin configuration, subsidence development through time, sediment influx and storage patterns, type of basin fill (e.g. salt vs. non-salt systems; carbonate-rich vs. clastics-dominated systems) and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development. The diversity in the stratigraphic architecture of the conjugate margins offshore southern Brazil, Namibia and Angola reflects variations in the interplay of a number of controlling factors, of which the most important are (a) the structural configuration of each margin segment at the time of break-up, (b) the post break-up subsidence history of the respective margin segment, (c) variations in the type, quantity and distribution of margin sediment, and (d) sea-level changes.

Strozyk, Frank; Back, Stefan; Kukla, Peter

2014-05-01

322

Monitoring ice break-up on the Mackenzie River, Canada, from MODIS Aqua and Terra observations  

NASA Astrophysics Data System (ADS)

Monitoring the response of river ice phenology to variability and changes in high-latitude climate conditions is critical for improving our understanding of northern hydrology and related impacts on geochemical and biological processes. Shorter ice cover duration, thinner ice, and earlier break-up also influence the winter road season, thereby influencing industrial development and the delivery of goods to northern communities. Increased upstream temperatures over the Mackenzie River Basin have caused shorter ice cover seasons, consequently changing the timing and severity of river ice flow in this high-latitude region. This study involves the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) Level 3 500-m snow products (Aqua and Terra), complemented with 250-m Level 1b data, to monitor ice cover during the break-up period on the Mackenzie River over the 2001-2013 period. Results from the analysis of 10 ice seasons (2003-2012) show that first day ice-off was observed between day of year (DY) 115-125 and ended between DY 145-155, resulting in average melt durations of about 30-40 days. Additional ice-on and ice-off days observed during 2003-2012 resulted from northern flowing entrained river ice that extended the break-up season until DY 155-163. Floating ice flowing northbound could therefore generate multiple periods of ice-cover and ice-free days at the same geographic location. During the ice break-up seasons from 2003-2012, ice melt was initiated by in situ melt over drainage basin (thermodynamic), especially between 61-62o N. However, ice break-up above the 62o N was more dynamically driven. In addition, ice jams were found to be largely controlled by river morphology.

Muhammad, P.; Duguay, C. R.; Kang, K.

2013-12-01

323

Using Synthetic Aperture Radar to Study River Ice Breakup on the Kuparuk River, Northern Alaska  

NASA Astrophysics Data System (ADS)

A combined use of remote sensing techniques and in-situ measurements is an effective approach to study Arctic hydrology, given the vastness, complexity, and logistical challenges posed by most Arctic watersheds. Remote sensing techniques can provide tools to assess the geospatial variations that form the integrated response of a river system and, therefore, provide important details to study one of the effects of climate change on the remote Arctic environment. This study investigates the breakup response of the Kuparuk River on the North Slope of Alaska using synthetic aperture radar (SAR). Imagery and runoff data collected during the spring and summer months between 2001 and 2010 from the Lower Kuparuk River are included in the analysis, which totals 65 SAR images. Image processing results have been calibrated with in-situ stream gauge data provided by USGS gauging station 15896000, on the Lower Kuparuk River, near the town of Deadhorse, Alaska. A time series was assembled to examine the breakup initiation in the subsets through statistical analysis. Images were stacked, geocoded using a Fast Fourier Transform, subset, masked, and divided into subsections. The statistics of each subsection were then compiled and analyzed. Arctic river breakup is a dynamic process. Therefore, we expected drastic change in river surface conditions to correspond to a large variance in backscatter between river subsections. However, before and after breakup we expected image subsections to have largely homogenous statistics. This was verified in nearly all of the image sets, although some variance still existed before and after the breakup event as a result of other conflicting variables. Changes in wind velocity, water depth, and size of point bars all contributed to these confounding variances. Combined with a comprehensive field campaign, SAR imagery interpretations have the potential to develop into a useful monitoring tool for monitoring Arctic rivers and developing resource management plans for neighboring communities.

Floyd, A.; Prakash, A.; Meyer, F. J.; Gens, R.; Liljedahl, A. K.

2012-12-01

324

Attachment Styles and Personal Growth following Romantic Breakups: The Mediating Roles of Distress, Rumination, and Tendency to Rebound  

PubMed Central

The purpose of this research was to examine the associations of attachment anxiety and avoidance with personal growth following relationship dissolution, and to test breakup distress, rumination, and tendency to rebound with new partners as mediators of these associations. Study 1 (N?=?411) and Study 2 (N?=?465) measured attachment style, breakup distress, and personal growth; Study 2 additionally measured ruminative reflection, brooding, and proclivity to rebound with new partners. Structural equation modelling revealed in both studies that anxiety was indirectly associated with greater personal growth through heightened breakup distress, whereas avoidance was indirectly associated with lower personal growth through inhibited breakup distress. Study 2 further showed that the positive association of breakup distress with personal growth was accounted for by enhanced reflection and brooding, and that anxious individuals’ greater personal growth was also explained by their proclivity to rebound. These findings suggest that anxious individuals’ hyperactivated breakup distress may act as a catalyst for personal growth by promoting the cognitive processing of breakup-related thoughts and emotions, whereas avoidant individuals’ deactivated distress may inhibit personal growth by suppressing this cognitive work. PMID:24066169

Marshall, Tara C.; Bejanyan, Kathrine; Ferenczi, Nelli

2013-01-01

325

Meson Photoproduction off the Deuteron and off 3He Department of Physics, University of Basel, Klingelbergstrasse. 82  

E-print Network

Meson Photoproduction off the Deuteron and off 3He B. Krusche Department of Physics, University of Basel, Klingelbergstrasse. 82 Basel, Switzerland Abstract. Photoproduction of mesons off the deuteron). Meson photoproduction off the neutron has been investigated for different final states (o, oo, o

Krusche, Bernd

326

Quantum Field Theory, and Screening the Coulomb Potential by Mobile Deuterons for the Low-Energy Nuclear Reaction  

Microsoft Academic Search

The Coulomb potential is screened by high density mobile deuterons more than the electrons in the PdDx deuteride, and the coherent motion of deuteron might play an important role for analysis of the low-energy nuclear reaction in condensed matter. Together with the group theoretical approach used in nuclear physics, the quantum field theory might provide a sound foundation for analysis

Hiroshi Takahashi

2005-01-01

327

Tear Film Breakup and Structure Studied by Simultaneous Video Recording of Fluorescence and Tear Film Lipid Layer Images  

PubMed Central

Purpose. The thinning of the precorneal tear film between blinks and tear film breakup can be logically analyzed into contributions from three components: evaporation, flow into the cornea, and tangential flow along the corneal surface. Whereas divergent tangential flow contributes to certain types of breakup, it has been argued that evaporation is the main cause of tear thinning and breakup. Because evaporation is controlled by the tear film lipid layer (TFLL) it should therefore be expected that patterns of breakup should match patterns in the TFLL, and this hypothesis is tested in this study. Methods. An optical system is described for simultaneous video imaging of fluorescein tear film breakup and the TFLL. Recordings were made from 85 subjects, including both with healthy and dry eyes. After instillation of 5 ?L2% fluorescein, subjects were asked to blink 1 second after the start of the recording and try to maintain their eyes open for the recording length of 30 or 60 seconds. Results. Areas of tear film thinning and breakup usually matched corresponding features in the TFLL. Whereas thinning and breakup were often matched to thin lipid, surprisingly, the corresponding lipid region was not always thinner than the surrounding lipid. Occasionally, a thin lipid region caused a corresponding region of greater fluorescence (thicker aqueous layer), due to convergent tangential flow. Conclusions. Areas of tear thinning and breakup can generally be matched to corresponding regions of the TFLL as would be expected if breakup is largely due to evaporation. Surprisingly, in some examples, the corresponding lipid area was not thinner and possibly thicker than the surrounding lipid. This indicates that the lipid was a poor barrier to evaporation, perhaps because of deficiency in composition and/or structure. For example, bacterial lipases may have broken down esters into component acids and alcohols, causing a defective TFLL structure with increased evaporation. PMID:23766476

King-Smith, P. Ewen; Reuter, Kathleen S.; Braun, Richard J.; Nichols, Jason J.; Nichols, Kelly K.

2013-01-01

328

Deuteron cross section evaluation for safety and radioprotection calculations of IFMIF/EVEDA accelerator prototype  

NASA Astrophysics Data System (ADS)

In the frame of IFMIF/EVEDA activities, a prototype accelerator delivering a high power deuteron beam is under construction in Japan. Interaction of these deuterons with matter will generate high levels of neutrons and induced activation, whose predicted yields depend strongly on the models used to calculate the different cross sections. A benchmark test was performed to validate these data for deuteron energies up to 20 MeV and to define a reasonable methodology for calculating the cross sections needed for EVEDA. Calculations were performed using the nuclear models included in MCNPX and PHITS, and the dedicated nuclear model code TALYS. Although the results obtained using TALYS (global parameters) or Monte Carlo codes disagree with experimental values, a solution is proposed to compute cross sections that are a good fit to experimental data. A consistent computational procedure is also suggested to improve both transport simulations/prompt dose and activation/residual dose calculations required for EVEDA.

Blideanu, Valentin; García, Mauricio; Joyer, Philippe; López, Daniel; Mayoral, Alicia; Ogando, Francisco; Ortíz, Félix; Sanz, Javier; Sauvan, Patrick

2011-10-01

329

Nondestructive determination of traces of light elements in molybdenum powder and alloys by deuteron activation analysis  

SciTech Connect

The authors use deuteron activation activation analysis to determine traces of other elements in molybdenum powder and an alloy of molybdenum with rhenium. The content of the elements in the samples was determined by comparison. Graphite and MoO/sub 3/ were taken as the reference substances for carbon and oxygen respectively. It is pointed out that radionuclides are formed in exothermal reactions from practically all molybdenum isotopes; they interfere in the determination of the trace elements. These interferences can be reduced by irradiation of the samples at deuteron energies which are significantly lower than the Coulombic barrier of molybdenum. The developed method of deuteron activation analysis can be used to determine C, O, Al, Na, Cl, and Mn at concentrations of 0.1-1.0 microg/g without destruction of the molybdenum samples.

Mukhammedov, S.; Rakhmonov, A.A.

1986-04-01

330

Results of Predictive Fokker-Planck Modelling of NBI Deuterons in ITER  

NASA Astrophysics Data System (ADS)

First an analytical formalism is presented for calculating the source distribution of ions generated by neutral beam injection (NBI) in tokamak plasmas. A general NBI ion source term, applicable to studies in the phase space up to 6 dimensions, is provided for neutral beams with finite thickness and divergence. Further, using this source term for the envisaged NBI in ITER, we carry out 3D Fokker-Planck modelling of the steady-state deuteron distribution function of NBI produced fast deuterons relaxing on bulk plasma components. For two basic ITER scenarios we demonstrate the poloidal profiles of the beam deuteron density, of the NBI generated current as well as of the NBI power deposition to bulk electrons and ions. Further, we evaluate the capability of gamma and NPA diagnostics of NBI ions in ITER and demonstrate the sensitivity of the distributions of NBI generated ions to different ITER operation scenarios.

Yavorskij, V.; Schoepf, K.; Goloborod'ko, V.; Cecconello, M.; Eriksson, L.-G.; Khan, M.; Kiptily, V.; Korotkov, A.; Polevoi, A.; Sharapov, S.; Reznik, S.

2011-08-01

331

Deuteron energy of 15 MK in ultra-dense deuterium without plasma formation: Temperature of the interior of the Sun  

NASA Astrophysics Data System (ADS)

Deuterons are released with kinetic energy up to 630 eV from ultra-dense deuterium as shown previously, by Coulomb explosions initiated by ns laser pulses at ?10 W cm. With higher laser intensity at <10 W cm, the initial kinetic energy now observed by TOF-MS with variable acceleration energy is up to 1100 eV per deuteron. This indicates ejection of one deuteron by Coulomb repulsion from two stationary charges in the material. It proves a full kinetic energy release of 1260 eV or a deuteron temperature of 15 MK, similar to the temperature in the interior of the Sun. Plasma processes are excluded by the sharp TOF peaks observed and by the slow signal variation with laser intensity. Deuterons with even higher energy from multiple charge repulsion are probably detected. D + D fusion processes are expected to exist in the ultra-dense phase without plasma formation.

Andersson, Patrik U.; Holmlid, Leif

2010-06-01

332

Excitation of giant monopole resonance in 208Pb and 116Sn using inelastic deuteron scattering  

NASA Astrophysics Data System (ADS)

The excitation of the isoscalar giant monopole resonance (ISGMR) in 208Pb and 116Sn has been investigated using small-angle (including 0°) inelastic scattering of 100 MeV/u deuteron and multipole-decomposition analysis (MDA). The extracted strength distributions agree well with those from inelastic scattering of 100 MeV/u ? particles. These measurements establish deuteron inelastic scattering at Ed ? 100 MeV /u as a suitable probe for extraction of the ISGMR strength with MDA, making feasible the investigation of this resonance in radioactive isotopes in inverse kinematics.

Patel, D.; Garg, U.; Itoh, M.; Akimune, H.; Berg, G. P. A.; Fujiwara, M.; Harakeh, M. N.; Iwamoto, C.; Kawabata, T.; Kawase, K.; Matta, J. T.; Murakami, T.; Okamoto, A.; Sako, T.; Schlax, K. W.; Takahashi, F.; White, M.; Yosoi, M.

2014-07-01

333

Importance of the Doppler Effect to the Determination of the Deuteron Binding Energy  

E-print Network

The deuteron binding energy extracted from the reaction ${}^1H(n,\\gamma){}^2H$ is reviewed with the exact relativistic formula, where the initial kinetic energy and the Doppler effect are taken into account. We find that the negligible initial kinetic energy of the neutron could cause a significant uncertainty which is beyond the errors available up to now. Therefore, we suggest an experiment which should include the detailed informations about the initial kinetic energy and the detection angle. It could reduce discrepancies among the recently reported values about the deuteron binding energy and pin down the uncertainty due to the Doppler broadening of $\\gamma$ ray.

Yongkyu Ko; Myung Ki Cheoun; Il-Tong Cheon

1999-04-01

334

Measurement of (anti)deuteron and (anti)proton production in DIS at HERA  

E-print Network

The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV using an integrated luminosity of 120 pb-1. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements.

Chekanov, S; Magill, S; Musgrave, B; Nicholass, D; Repond, J; Yoshida, R; Mattingly, M C K; Jechow, M; Pavel, N; Yagues-Molina, A G; Antonelli, S; Antonioli, P; Bari, G; Basile, M; Bellagamba, L; Bindi, M; Boscherini, D; Bruni, A; Bruni, G; Cifarelli, L; Cindolo, F; Contin, A; Corradi, M; De Pasquale, S; Iacobucci, G; Margotti, A; Nania, R; Polini, A; Sartorelli, G; Zichichi, A; Bartsch, D; Brock, I; Goers, S; Hartmann, H; Hilger, E; Jakob, H P; Jüngst, M; Kind, O M; Nuncio-Quiroz, A E; Paul, E; Renner, R; Samson, U; Schonberg, V; Shehzadi, R; Wlasenko, M; Brook, N H; Heath, G P; Morris, J D; Namsoo, T; Capua, M; Fazio, S; Mastroberardino, A; Schioppa, M; Susinno, G; Tassi, E; Kim, J Y; Ma, K J; Ibrahim, Z A; Kamaluddin, B; Wan-Abdullah, W A T; Ning, Y; Ren, Z; Sciulli, F; Chwastowski, J; Eskreys, A; Figiel, J; Galas, A; Gil, M; Olkiewicz, K; Stopa, P; Zawiejski, L; Adamczyk, L; Bold, T; Grabowska-Bold, I; Kisielewska, D; Lukasik, J; Przybycien, M; Suszycki, L; Kotanski, A; Slominski, W; Adler, V; Behrens, U; Bloch, I; Blohm, C; Bonato, A; Borras, K; Ciesielski, R; Coppola, N; Dossanov, A; Drugakov, V; Fourletova, J; Geiser, A; Gladkov, D; Göttlicher, P; Grebenyuk, J; Gregor, I; Haas, T; Hain, W; Horn, C; Huttmann, A; Kahle, B; Katkov, I I; Klein, U; Kötz, U; Kowalski, H; Lobodzinska, E; Löhr, B; Mankel, R; Melzer-Pellmann, I A; Miglioranzi, S; Montanari, A; Notz, D; Rinaldi, L; Roloff, P; Rubinsky, I; Santamarta, R; Schneekloth, U; Spiridonov, A; Stadie, H; Szuba, D; Szuba, J; Theedt, T; Wolf, G; Wrona, K; Youngman, C; Zeuner, W; Lohmann, W; Schlenstedt, S; Barbagli, G; Gallo, E; Pelfer, P G; Bamberger, A; Dobur, D; Karstens, F; Vlasov, N N; Bussey, P J; Doyle, A T; Dunne, W; Ferrando, J; Forrest, M; Saxon, D H; Skillicorn, I O; Gialas, I; Papageorgiu, K; Gosau, T; Holm, U; Klanner, R; Lohrmann, E; Salehi, H; Schleper, P; Schörner-Sadenius, T; Sztuk, J; Wichmann, K; Wick, K; Foudas, C; Fry, C; Long, K R; Tapper, A D; Kataoka, M; Matsumoto, T; Nagano, K; Tokushuku, K; Yamada, S; Yamazaki, Y; Barakbaev, A N; Boos, E G; Pokrovskiy, N S; Zhautykov, B O; Aushev, V; Son, D; De Favereau, J; Piotrzkowski, K; Barreiro, F; Glasman, C; Jiménez, M; Labarga, L; Del Peso, J; Ron, E; Soares, M; Terron, J; Zambrana, M; Corriveau, F; Liu, C; Walsh, R; Zhou, C; Tsurugai, T; Antonov, A; Dolgoshein, B A; Sosnovtsev, V; Stifutkin, A; Suchkov, S; Dementiev, R K; Ermolov, P F; Gladilin, L K; Khein, L A; Korzhavina, I A; Kuzmin, V A; Levchenko, B B; Lukina, O Yu; Proskuryakov, A S; Shcheglova, L M; Zotkin, D S; Zotkin, S A; Abt, I; Büttner, C; Caldwell, A; Kollar, D; Schmidke, W B; Sutiak, J; Grigorescu, G; Keramidas, A; Koffeman, E; Kooijman, P; Pellegrino, A; Tiecke, H; Vázquez, M; Wiggers, L; Brümmer, N; Bylsma, B; Durkin, L S; Lee, A; Ling, T Y; Allfrey, P D; Bell, M A; Cooper-Sarkar, A M; Cottrell, A; Devenish, R C E; Foster, B; Korcsak-Gorzo, K; Patel, S; Roberfroid, V; Robertson, A; Straub, P B; Uribe-, C; Estrada; Walczak, R; Bellan, P; Bertolin, A; Brugnera, R; Carlin, R; Dal Corso, F; Dusini, S; Garfagnini, A; Limentani, S; Longhin, A; Stanco, L; Turcato, M; Oh, B Y; Raval, A; Ukleja, J; Whitmore, J J; Iga, Y; D'Agostini, G; Marini, G; Nigro, A; Cole, J E; Hart, J C; Abramowicz, H; Gabareen, A; Ingbir, R; Kananov, S; Levy, A; Kuze, M; Maeda, J; Hori, R; Kagawa, S; Okazaki, N; Shimizu, S; Tawara, T; Hamatsu, R; Kaji, H; Kitamura, S; Ota, O; Ri, Y D; Ferrero, M I; Monaco, V; Sacchi, R; Solano, A; Arneodo, M; Ruspa, M; Fourletov, S; Martin, J F; Boutle, S K; Butterworth, J M; Gwenlan, C; Jones, T W; Loizides, J H; Sutton, M R; Wing, M; Brzozowska, B; Ciborowski, J; Grzelak, G; Kulinski, P; Luzniak, P; Malka, J; Nowak, R J; Pawlak, J M; Tymieniecka, T; Ukleja, A; Zarnecki, A F; Adamus, M; Plucinsky, P P; Eisenberg, Y; Giller, I; Hochman, D; Karshon, U; Rosin, M; Brownson, E; Danielson, T; Everett, A; Kcira, D; Reeder, D D; Ryan, P; Savin, A A; Smith, W H; Wolfe, H; Bhadra, S; Catterall, C D; Cui, Y; Hartner, G; Menary, S; Noor, U; Standage, J; Whyte, J

2007-01-01

335

Comparative analysis of properties of channels of deuteron and tritium production in 16O p collisions at a projectile momentum of 3.25 GeV/ c per nucleon  

NASA Astrophysics Data System (ADS)

The results of a comparative analysis of channels involving the inclusive production of deuterons and tritons in 16O p collisions at a projectile momentum of 3.25 GeV/ c per nucleon are presented. The mechanisms governing proton, deuteron, and triton production in the fragmentation of oxygen nuclei are found to be independent. It is shown that the observed proton-multiplicity correlations are associated predominantly with the character of the primary event of a proton-nucleon collision in 16O p interactions. It is found that, in reactions involving triton production, the contributions of processes leading to an increase in the mean proton multiplicity ( n ? p + ? - and np ? pn) and processes leading to its decrease ( p ? n + ? +) compensate each other.

Olimov, K.; Glagolev, V. V.; Gulamov, K. G.; Kurbanov, A.; Lutpullaev, S. L.; Olimov, A. K.; Petrov, V. I.; Yuldashev, A. A.

2014-12-01

336

Effective Search Strategy Applicable for Breakup Fragments in the Geostationary Region  

NASA Astrophysics Data System (ADS)

This paper proposes to apply the orbital debris modeling techniques to devise an effective search strategy applicable for breakup fragments in the geostationary region. The orbital debris modeling techniques describe debris generation and propagation to effectively conduct predictive analyses of space objects that include characterizing, tracking and predicting the behavior of individual and groups of space objects. Therefore, the techniques enable us to predict population of debris from a specific breakup. The population prediction specifies effectively when, where and how we should conduct optical measurements using ground-based telescopes. The orbital debris modeling techniques also enable us to predict motion of debris in successive images. The motion prediction specifies effectively and precisely how we should process successive images of objects in the geostationary region, taken with ground-based telescopes. This paper also validates the proposed search strategy through actual observations, targeting the US Titan IIIC transtage explosion in the geostationary region.

Uetsuhara, M.; Kitazawa, Y.; Yanagisawa, T.; Hanada, T.

2011-09-01

337

The Breakup of a Main-Belt Asteroid 450 Thousand Years Ago  

NASA Astrophysics Data System (ADS)

Collisions in the asteroid belt frequently lead to catastrophic breakups, where more than half of the target's mass is ejected into space. Several dozen large asteroids have been disrupted by impacts over the past several billion years. These impact events have produced groups of fragments with similar orbits called asteroid families. Here we report the discovery of a very young asteroid family around the object 1270 Datura. Our work takes advantage of a method for identification of recent breakups in the asteroid belt using catalogs of osculating (i.e., instantaneous) asteroid orbits. The very young families show up in these catalogs as clusters in a five-dimensional space of osculating orbital elements.

Nesvorny, D.; Vokrouhlicky, D.; Bottke, W. F.

2006-06-01

338

Breakup of an electrified, perfectly conducting, viscous thread in an AC field  

NASA Astrophysics Data System (ADS)

We study the axisymmetric breakup and satellite formation of slender jets surrounded by a concentrically placed cylindrical electrode and subjected to time-dependent AC electric fields. The jet is assumed to be a perfectly conducting viscous fluid and surrounded by a dielectric inviscid gas. We use the long-wave approximation to derive coupled evolution equations for the interface position and the axial velocity component, which accounts for electrostatic forcing. The electrostatic force in this case is large and competes with capillary forces near the rupture point, causing the interface to oscillate and the satellite to have shapes that are distinct from the DC case. In particular, our results indicate that it may be possible to use the AC field to control the number of satellites accompanying breakup as well as their size.

Conroy, D. T.; Matar, O. K.; Craster, R. V.; Papageorgiou, D. T.

2011-06-01

339

The Atlas-Centaur 67 incident. [meteorological conditions during lightning caused breakup upon ascent  

NASA Technical Reports Server (NTRS)

The conditions leading to the breakup of the Atlas-Centaur 67 (AC-67) vehicle launched on March 26, 1987 during a typical winter-time storm are analyzed, and a most probable lightning strike scenario was developed based on inspection of the AC-67 debris, the AC-68 vehicle, and appropriate drawings, electrical diagrams, and photographs. It is shown that, during ascent, the vehicle encountered increasingly larger electric fields and flew through clouds that produced precipitation static on the vehicle, eventually triggering a cloud-to-ground lightning, comprised of at least four return strokes. The resulting lightning current coupled a signal into the wiring which goes to the AC-67 digital computer unit (DCU), effecting a single-word memory alteration and causing the DCU to issue a hardover engine gimbal command. This led to an excessive angle of attack, large dynamic loads, and the breakup of the AC-67.

Christian, H. J.; Crouch, K.; Fisher, B.; Mazur, V.; Perala, R. A.

1988-01-01

340

Breakup of liquid filaments over a wide range of Ohnesorge number  

NASA Astrophysics Data System (ADS)

This work presents a study of the breakup of liquid filaments over a wide range of Ohnesorge numbers (0.001 to 10) using a simple large-scale jet generator. The experimental arrangement features a variable-size nozzle, whose radius can be adjusted from 100 ?m to 3 mm and which is capable of jetting liquids with viscosities between 1 mPa s and 1.4 Pa s. The actuator of this generator consists of an electromagnetic vibrator that can be driven by arbitrary waveforms in order to control the jet formation process. The instrumentation also includes a fast pressure transducer to monitor the true pressure drive produced by the actuator. The filament breakup behavior and distribution (regime diagram), in terms of aspect ratio and Ohnesorge number, is compared with the predictions from previously published models.

Castrejon-Pita, Alfonso A.; Castrejon-Pita, Jose R.; Hutchings, Ian M.

2011-11-01

341

First Measurement of the Tensor Structure Function b1 of the Deuteron.  

E-print Network

a loose compound. The more one gets them at a peel, however, the more they stick together. They give up or intrinsic angular momentum. See Figure 1.1 to get an impression about it. One assigns to every particle.1: The deuteron can align its spin only to the top (left picture) or to the front/back (right picture

342

First Measurement of the Tensor Structure Function b 1 of the Deuteron.  

E-print Network

a loose compound. The more one gets them at a peel, however, the more they stick together. They give up or intrinsic angular momentum. See Figure 1.1 to get an impression about it. One assigns to every particle.1: The deuteron can align its spin only to the top (left picture) or to the front/back (right picture

343

Extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements  

NASA Technical Reports Server (NTRS)

A method is presented for extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements within the framework of the Glauber approximation. This method, which involves the solution of a linear integral equation, is applied to pn collisions between 15 and 275 GeV/c. Effects arising from inelastic intermediate states are estimated.

Franco, V.

1977-01-01

344

Extraction of Neutron Structure Functions from (Semi)InclusiveDeuteron Data  

NASA Astrophysics Data System (ADS)

Structure functions parameterize fundamental information about the internal structure of the nucleon, and in the deep-inelastic region are given in terms of the longitudinal momentum distributions of the nucleons' quark and gluon constituents. Compared to the copious amount of proton structure function data, there is considerably less for the neutron, which is mainly derived from deuteron data. Extracting neutron structure functions from the deuteron results in ambiguities from the necessary nuclear corrections. Such ambiguities can be confronted using free neutron and proton and inclusive deuteron data. The Barely Off-shell Neutron Structure experiment (BoNuS) ran in experimental Hall B at Jefferson Lab in 2005 and provided a virtually free neutron target for the first time. Extraction of the free neutron structure functions has been performed via global fits to both the BoNuS and deuteron inclusive data, utilizing an existing fit to the free proton, within the framework of the weak binding approximation and utilizing various nuclear potentials. We will report on the results of this fitting effort and the consistency between neutron information from BoNuS and the impulse approximation.

Kalantarians, Narbe

2013-04-01

345

Momentum distribution of nucleons in the deuteron on the basis of the Moscow potential  

SciTech Connect

Themomentum distribution of nucleons in the deuteron is calculated for the Moscow and Paris nucleon-nucleon potentials. It is shown that the Moscow potential provides a better description of the distribution deduced from data on the reaction d(e, e Prime p)n in the region close to the kinematical region of quasielastic proton knockout.

Neudatchin, V. G. [Moscow State University, Institute of Nuclear Physics (Russian Federation); Khokhlov, N. A. [Komsomolsk-on-Amur State Technical University (Russian Federation)

2013-06-15

346

Antideuteron and deuteron production in midcentral Pb+Pb collisions at 158A GeV  

E-print Network

Production of deuterons and antideuterons was studied by the NA49 experiment in the 23.5% most central Pb+Pb collisions at the top CERN Super Proton Synchroton (SPS) energy of ?s[subscript NN]=17.3 GeV. Invariant yields ...

Roland, Christof E.

347

Spin Physics Experiments at NICA-SPD with polarized proton and deuteron beams  

NASA Astrophysics Data System (ADS)

The brief description of the Letter of Intent proposing primarily to perform measurements of asymmetries of the DY pair production in collisions of non-polarized, longitudinally and transversally polarized protons and deuterons which provide an access to all leading twist collinear and TMD PDFs of quarks and anti-quarks in nucleons.

Savin, I.; Efremov, A.; Peshekhonov, D.; Kovalenko, A.; Teryaev, O.; Shevchenko, O.; Nagajcev, A.; Guskov, A.; Kukhtin, V.; Toplilin, N.

2015-01-01

348

b1 and the Angular Momentum Sum Rule in the Deuteron  

NASA Astrophysics Data System (ADS)

We formulate the generalized deep inelastic tensor spin structure of the deuteron which can be obtained from deeply virtual Compton scattering and meson production experiments. We discuss its connection to the total quark angular momentum sum rule for a spin-one hadronic system within a gauge invariant decomposition of hadronic spin.

Liuti, S.; Kathuria, K.

2014-10-01

349

Effective field theory calculation of two-deuteron radiative capture reaction at astrophysical energies  

NASA Astrophysics Data System (ADS)

Two-deuteron radiative capture reaction is one of the deuterium-burning processes that the cross section is not well known at very low-energies. We develop the formalism based on pionless Effective Field Theory (EFT) for deuteron-deuteron ( dd) scattering to derive the cross section of two-deuteron radiative capture. Within this formalism the two- and three-body forces, should also be included in the capture cross section calculations. The aim of the present work is to calculate the observables of the low-energy dd photonuclear reactions. The cross section and the astrophysical S-factor for the 2H( d, ?)4He reaction have been calculated. The 4He is studied as four-body bound states in the pionless EFT. The theoretical uncertainties for observables are estimated based on the variation of the cutoffs. The astrophysical S-factor is accurately determined to be 6.9×10-6 keV b (6.1×10-6 keV b) for two-body (two- and three-body) at zero energy. A satisfactory agreement between theory and experiment for dd radiative capture observables up to order of calculation has been found by insertion of three-body force.

Sadeghi, H.; Khalili, H.

2014-08-01

350

Neutron and high energy deuteron anisotropy investigations in plasma focus device  

NASA Astrophysics Data System (ADS)

The anisotropies of neutron and high energy deuteron emissions from the NX2 plasma focus device [M. V. Roshan et al., Phys. Lett. A 373, 851 (2009)] are studied. The nuclear activation of graphite targets is used to measure the fluences of high energy deuterons in the axial and radial directions. Two bismuth germanate scintillation detectors connected to multichannel analyzer systems are used for the detection of 511 keV gamma rays resulting from positron annihilation in the two targets. In addition, fast neutron activation detectors are employed to measure the axial and radial fluences of fusion neutrons. These detection systems are calibrated using the simulation code MCNPX [L. S. Waters et al., AIP Conf. Proc. 896, 81 (2007)]. Two distinct regimes of neutron and deuteron anisotropies are observed for the NX2 device. For deuterium gas pressures below 10 mbar, the neutron anisotropy increases with increasing pressure, while the overall neutron yield remains low. For gas pressures of 10-14 mbar, the neutron anisotropy is essentially constant, while, with increasing pressure, the neutron yield rises rapidly and the deuteron anisotropy falls.

Roshan, M. V.; Rawat, R. S.; Talebitaher, A.; Lee, P.; Springham, S. V.

2009-05-01

351

Deformation and Break-up of Suspension Droplets Sheared in an Immiscible Fluid  

NASA Astrophysics Data System (ADS)

The deformation and break-up behaviour of suspension droplets immersed in an immiscible fluid has not been widely studied albeit such systems are frequently encountered in every day multiphase products such as foods and cosmetics. Starch is a common thickener used in the food industry. Starch suspensions have shown to offer better flavour perception than polymer thickened solutions; a better understanding of their behaviour under flow would be beneficial in terms of advancement on product formulation. Deformation and break-up of a droplet of swollen-in-water starch granules placed in high viscosity silicon oil was visualised using a counter-rotating parallel-plate shear cell. The silicon oil had a high viscosity to induce shear stresses high enough to deform the droplet; it is also transparent and inert towards the studied system. The starch suspension was prepared to have a volume fraction of 100% swollen granules, i.e. that all water was bound within the swollen starch granules. The shear flow behaviour of this starch suspension is characterised by an apparent yield stress, shear-thinning and first normal stress differences. The rheo-optical experiments were conducted as start-up flow experiments applying shear stresses above the apparent yield stress. A constant shear stress throughout the experiment allows a constant viscosity of the droplet and therefore rules out the shear thinning aspect. Analysis showed droplet break-up at critical Capillary numbers close to those reported for Newtonian fluids. The results demonstrate that the droplet break-up behaviour in a complex emulsion system submitted to shear flow may not be fully described by the rheology of the individual phases alone but may require a microstructure component.

Desse, Melinda; Hill, Sandra E.; Mitchell, John R.; Wolf, Bettina; Budtova, Tatiana

2008-07-01

352

Dynamics of Growth and Breakup of Viscous Pendant Drops into Air.  

PubMed

This paper presents a numerical study of the dynamics of a viscous liquid drop that is being formed directly at the tip of a vertical tube into ambient air. A model is developed to predict the evolution of the drop shape and its breakup based on RIPPLE, which is a solution algorithm for computing transient, two-dimensional, incompressible fluid flow with surface tension on free surfaces of general topology (D. B. Kothe and R. C. Mjolsness, AIAA J. 30, 2694 (1992)). The full Navier-Stokes system is solved by using finite-difference formulation on a Eulerian mesh. The mesh is fixed in space, with the flow and surface moving through it to ensure accurate calculations of complex free surface flows and topology, including surface breakup and coalescence. The novel feature of the numerical algorithm is the use of a Eulerian volume-tracking approach which allows the calculations to pass the breaking point during formation of a drop continuously without interruption or numerical modification and, therefore, to explore the features of generation of satellite droplets. The effects of physical and geometric parameters on the nonlinear dynamics of drop growth and breakup are investigated. The focus here is on drop breakup and subsequent formation of satellite droplets. The effects of finite inertial, capillary, viscous, and gravitational forces are all accounted for to classify different formation dynamics and to elucidate features of satellite droplet generation. The numerical predictions are compared with experimental measurements for water drops, and the results show good agreement. Copyright 1999 Academic Press. PMID:10072280

Zhang

1999-04-01

353

Low-altitude acceleration of auroral electrons during breakup observed by a mother-daughter rocket  

NASA Technical Reports Server (NTRS)

By the use of a mother-daughter rocket combination and ground-based observations with television, time and space variations are resolved in particle measurements in breakup aurora. The spectral variations measured during a temporal variation in the aurora can be explained by a nearly uniform acceleration of all the electrons such as would be caused by an electric potential drop along the magnetic field lines. Many other explanations can be eliminated.

Johnstone, A. D.; Davis, T. N.

1974-01-01

354

High-Speed Microscopic Imaging of the Initial Stage of Diesel Spray Formation and Primary Breakup  

Microsoft Academic Search

The formation and breakup of diesel sprays was investigated experimentally on a common rail diesel injector using a long range microscope. The objectives were to further the fundamental understanding of the processes involved in the initial stage of diesel spray formation.\\u000d\\u000a\\u000d\\u000aTests were conducted at atmospheric conditions and on a rapid compression machine with motored in-cylinder peak pressures up to

Cyril Crua; Tenzin Shoba; Morgan Heikal; Martin Gold; Cassandra Higham

2010-01-01

355

Simulations of the Breakup of Comet Shoemaker-Levy 9 Employing a Swarm Model: Initial Conditions  

NSDL National Science Digital Library

The breakup of comet Shoemaker-Levy 9 due to its gravitational interaction with Jupiter in July, 1994 is simulated using a swarm model. In this simulation, the comet is modeled as an initially spherical distribution of 16,384 particles. The particles interact with the tidal field of Jupiter and with each other through inter-particle gravitation and collisions. All simulations were performed on the Maspar MP-2 at NASA-GSFC.

Kevin Olson

1995-03-24

356

Simulations of the Breakup of Comet Shoemaker-Levy 9 Employing a Swarm Model: Dynamical Evolution  

NSDL National Science Digital Library

The breakup of comet Shoemaker-Levy 9 due to its gravitational interaction with Jupiter in July, 1994 is simulated using a swarm model. In this simulation, the comet is modeled as an initially spherical distribution of 16,384 particles. The particles interact with the tidal field of Jupiter and with each other through inter-particle gravitation and collisions. All simulations were performed on the Maspar MP-2 at NASA-GSFC.

Kevin Olson

1995-03-24

357

Structure of 23Al from the one-proton breakup reaction and astrophysical implications  

Microsoft Academic Search

The ground state of the proton-rich nucleus 23Al has been studied by one-proton removal on a carbon target at about 50 MeV\\/nucleon using the EXOGAM + SPEG experimental setup at GANIL. Longitudinal momentum distributions of the 22Mg breakup fragments, inclusive and in coincidence with gamma rays de-exciting the residues, were measured. The ground-state structure of 23Al is found to be

A. Banu; L. Trache; F. Carstoiu; N. L. Achouri; A. Bonaccorso; W. N. Catford; M. Chartier; M. Dimmock; B. Fernández-Domínguez; M. Freer; L. Gaudefroy; M. Horoi; M. Labiche; B. Laurent; R. C. Lemmon; F. Negoita; N. A. Orr; S. Paschalis; N. Patterson; E. S. Paul; M. Petri; B. Pietras; B. T. Roeder; F. Rotaru; P. Roussel-Chomaz; E. Simmons; J. S. Thomas; R. E. Tribble

2011-01-01

358

How does breakup influence near-barrier fusion of weakly bound light nuclei ?  

E-print Network

The influence on the fusion process of coupling to collective degrees of freedom has been explored. The significant enhancement of he fusion cross setion at sub-barrier energies was understood in terms of the dynamical processes arising from strong couplings to collective inelastic excitations of the target and projectile. However, in the case of reactions where breakup becomes an important process, conflicing model predictions and experimental results have been reported in the literature. Excitation functions for sub- and near-barrier total (complete + incomplete) fusion cross sections have been measured for the $^{6,7}$Li + $^{59}$Co at the Vivitron facility and at the 8UD Pelletron tandem facility using standard $\\gamma$-ray techniques. The data extend to medium-mass systems previous works exploring the coupling effects in fusion reactions of both lighter and heavier systems. Results of continuum-discretized coupled channel (CDCC) calculations indicate a small enhancement of total fusion for the more weakly bound $^{6}$Li at sub-barrier energies, with similar cross sections for both reactions at and above the barrier. A systematic study of $^{4,6}$He induced fusion reactions with the CDCC method is in progress. The understanding of the reaction dynamics involving couplings to the breakup channels requires th explicit measurement of precise elastic scattering data as well as yields leading to the breakup itself. Recent coincidence experiments for $^{6,7}$Li + $^{59}$Co are addressing this issue. The particle identification of the breakup products have been achieved by measuring the three-body final-state correlations.

C. Beck; N. Rowley; M. Rousseau; F. Haas; P. Bednarczyk; S. Courtin; N. Kintz; F. Hoellinger; P. Papka; S. Szilner; A. Sanchez I Zafra; A. Hachem; E. Martin; O. Stezowski; A. Diaz-Torres; F. A. Souza; A. Szanto De Toledo; A. Aissaoui; N. Carlin; R. Liguori Neto; M. G. Munhoz; J. Takahashi; A. A. P. Suade; M. M. De Moura; E. M. Szanto; K. Hagino; I. J. Thompson

2004-11-03

359

Breakup reactions of {sup 11}Li within a three-body model  

SciTech Connect

Breakup reactions of {sup 11}Li (n+n+{sup 9}Li) on a light target are investigated. The projectile-target interactions are described by phenomenological optical potentials. The model predicts dependence on beam energy and target, differences between longitudinal and transverse momentum distributions, and provides absolute values for all computed differential cross sections. Good agreement with the experimental data is obtained with a relative neutron-{sup 9}Li p-wave content of about 40%.

Garrido, E. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Fedorov, D. V.; Jensen, A. S. [Institute of Physics and Astronomy, DK-8000 Aarhus C (Denmark)

1999-11-16

360

Reaction mechanisms in the 6Li+59Co system  

E-print Network

The reactions induced by the weakly bound 6Li projectile interacting with the intermediate mass target 59Co were investigated. Light charged particles singles and $\\alpha$-$d$ coincidence measurements were performed at the near barrier energies E_lab = 17.4, 21.5, 25.5 and 29.6 MeV. The main contributions of the different competing mechanisms are discussed. A statistical model analysis, Continuum-Discretized Coupled-Channels calculations and two-body kinematics were used as tools to provide information to disentangle the main components of these mechanisms. A significant contribution of the direct breakup was observed through the difference between the experimental sequential breakup cross section and the CDCC prediction for the non-capture breakup cross section.

F. A . Souza; C. Beck; N. Carlin; N. Keeley; R. Liguori Neto; M. M. de Moura; M. G. Munhoz; M. G. Del Santo; A. A. P. Suaide; E. M. Szanto; A. Szanto de Toledo

2008-11-27

361

Effect of contact line motion on the deformation and breakup of stretching liquid bridges  

NASA Astrophysics Data System (ADS)

The use of pin-tools for the deposition of small quantities of liquids on substrates has gained popularity recently. Applications range from spotting of biochips in DNA arrayers to coloring of contact lenses. The pin-tool is nothing more than a stretching liquid bridge whose contact lines are allowed to move on one or both of the substrates between which the bridge liquid is held captive. In this paper, the effect of contact line motion on the stretching and breakup of the liquid bridge is analyzed. The movement of the contact line is modeled by means of Navier's slip law and a constant contact angle. In the computations, the full nonlinear, transient Navier-Stokes system is solved using the Galerkin/finite element method. The experiments rely on the use of high-speed digital imagers for visualization of the contact line motion and dynamics of bridge breakup. The partitioning of the liquid between the two substrates and the size of the spots formed on the substrates upon bridge breakup are determined as functions of the physical and the geometric properties of the bridge-substrate system and stretching velocity.

Ambravaneswaran, B.; Panditaratne, J. C.; Schreiweis, A. L.; Basaran, O. A.

1999-11-01

362

The breakup of digital microfluids on a piezoelectric substrate using surface acoustic waves.  

PubMed

A new method for the breakup of a digital microfluid (a discrete droplet) is presented and a device for splitting the digital microfluid is fabricated on a 128° yx-LiNbO3 piezoelectric substrate using microelectronic technology. Together with the surface tension of the digital microfluid, the inertia of acoustic streaming caused by the sudden disappearance of the electric signal for generating the surface acoustic wave breaks up the digital microfluid. The escape angle of the daughter digital microfluids is calculated. A sound-absorption film is coated on the acoustic path to prevent the further breakup of the daughter digital microfluids. Droplet breakups are demonstrated using red dye solution digital microfluids. Results show that digital microfluids can be broken up by suddenly decreasing the power of the electrical signal from 12.3 dBm to -3.98 dBm, and the average escape angle of daughter digital microfluids is 68.5° for 4 ?L of initial digital microfluid. The results also show that the escape angle is affected by the initial volume of the digital microfluid. PMID:25474784

Zhang, An-Liang; Zha, Yan

2014-12-01

363

Transverse liquid fuel jet breakup, burning, and ignition. M.S. Thesis  

NASA Technical Reports Server (NTRS)

An analytical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion. Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, were used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flame supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic cross flow. Typical flame structures and concentration profiles were calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integration reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.

Li, Hsi-Shang

1990-01-01

364

Transfer/Breakup Channel Couplings in Sub-barrier Fusion Reactions  

NASA Astrophysics Data System (ADS)

With the recent availability of state-of-the-art radioactive ion beams, there has been a renew interest in the investigation of nuclear reactions with heavy ions near the Coulomb barrier. The role of inelastic and transfer channel couplings in fusion reactions induced by stable heavy ions can be revisited. Detailed analysis of recent experimental fusion cross sections by using standard coupled-channel calculations is first discussed. Multi-neutron transfer effects are introduced in the fusion process below the Coulomb barrier by analyzing 32S+90,96Zr as benchmark reactions. The enhancement of fusion cross sections for 32S+96Zr is well reproduced at sub-barrier energies by NTFus code calculations including the coupling of the neutrontransfer channels following the Zagrebaev semi-classical model. Similar effects for 40Ca+90Zr and 40Ca+96Zr fusion excitation functions are found. The breakup coupling in both the elastic scattering and in the fusion process induced by weakly bound stable projectiles is also shown to be crucial. In the second part of this work, full coupled-channel calculations of the fusion excitation functions are performed by using the breakup coupling for the more neutron-rich reaction and for the more weakly bound projectiles. We clearly demonstrate that Continuum-Discretized Coupled-Channel calculations are capable to reproduce the fusion enhancement from the breakup coupling in 6Li+59Co.

Beck, C.

2013-03-01

365

A user`s guide for BREAKUP: A computer code for parallelizing the overset grid approach  

SciTech Connect

In this user`s guide, details for running BREAKUP are discussed. BREAKUP allows the widely used overset grid method to be run in a parallel computer environment to achieve faster run times for computational field simulations over complex geometries. The overset grid method permits complex geometries to be divided into separate components. Each component is then gridded independently. The grids are computationally rejoined in a solver via interpolation coefficients used for grid-to-grid communications of boundary data. Overset grids have been in widespread use for many years on serial computers, and several well-known Navier-Stokes flow solvers have been extensively developed and validated to support their use. One drawback of serial overset grid methods has been the extensive compute time required to update flow solutions one grid at a time. Parallelizing the overset grid method overcomes this limitation by updating each grid or subgrid simultaneously. BREAKUP prepares overset grids for parallel processing by subdividing each overset grid into statically load-balanced subgrids. Two-dimensional examples with sample solutions, and three-dimensional examples, are presented.

Barnette, D.W.

1998-04-01

366

Neutron-3H scattering above the four-nucleon breakup threshold  

NASA Astrophysics Data System (ADS)

Background: Theoretical calculations of the four-body scattering above the four-body breakup threshold are technically very difficult owing to complicated singularities in the momentum space or boundary conditions in the coordinate space.Purpose: We aim at calculating the neutron-3H scattering observables above the four-nucleon breakup threshold.Methods: We employ Alt, Grassberger, and Sandhas (AGS) integral equations for the four-nucleon transition operators and solve them in the momentum-space framework using the complex-energy method. We significantly improve its accuracy and practical applicability by introducing the numerical integration method with the special weights.Results: Using realistic nuclear interaction models we obtain fully converged results for the neutron-3H scattering. Elastic differential cross section and neutron analyzing power as well as the total cross section are calculated at 14.1, 18.0, and 22.1 MeV neutron energy.Conclusions: Realistic four-nucleon scattering calculations above the four-nucleon breakup threshold are feasible. There is quite good agreement between the theoretical predictions and experimental data for the neutron-3H scattering in the considered energy regime.

Deltuva, A.; Fonseca, A. C.

2012-07-01

367

Facebook Surveillance of Former Romantic Partners: Associations with PostBreakup Recovery and Personal Growth  

PubMed Central

Abstract Previous research has found that continuing offline contact with an ex-romantic partner following a breakup may disrupt emotional recovery. The present study examined whether continuing online contact with an ex-partner through remaining Facebook friends and/or engaging in surveillance of the ex-partner's Facebook page inhibited postbreakup adjustment and growth above and beyond offline contact. Analysis of the data provided by 464 participants revealed that Facebook surveillance was associated with greater current distress over the breakup, more negative feelings, sexual desire, and longing for the ex-partner, and lower personal growth. Participants who remained Facebook friends with the ex-partner, relative to those who did not remain Facebook friends, reported less negative feelings, sexual desire, and longing for the former partner, but lower personal growth. All of these results emerged after controlling for offline contact, personality traits, and characteristics of the former relationship and breakup that tend to predict postbreakup adjustment. Overall, these findings suggest that exposure to an ex-partner through Facebook may obstruct the process of healing and moving on from a past relationship. PMID:22946958

2012-01-01

368

Extension of a CLSVOF method for droplet-laden flows with a coalescence/breakup model  

NASA Astrophysics Data System (ADS)

A multiple marker Coupled Level-Set/Volume-of-Fluid (CLSVOF) method for droplet-laden flows has been extended with a physical model to accommodate coalescence and breakup of the droplets. In the CLSVOF method each droplet has its own locally defined marker functions. This prevents the problem of numerical coalescence in conventional Level-Set and Volume-of-Fluid methods when two droplet interfaces are less than one grid cell apart from each other. In the present model coalescence is based on a computationally efficient film drainage model, which predicts if and when two colliding droplets will coalesce. If the contact time between two colliding droplets exceeds the predicted film drainage time, coalescence is numerically accomplished by merging the marker functions of the two separate droplets. Similarly, breakup of a droplet is accommodated by splitting the marker functions of the droplet. Simulations are shown for (near) head-on collision of two equal droplets at Weber numbers of 2.3, 9.33, 13.63, and 61.4, corresponding to four different collision regimes. The good agreement with the experimental data for each Weber number demonstrates the capability of the CLSVOF method to simulate coalescence and breakup with physical realism. A sensitivity study has shown a strong sensitivity of the collision dynamics on the prescribed film drainage time, while the influence of the spatial grid resolution appears to be small. This underlines the importance of accurate models for the film drainage time.

Kwakkel, Marcel; Breugem, Wim-Paul; Boersma, Bendiks Jan

2013-11-01

369

Complete Set of Deuteron Analyzing Powers for dp Elastic Scattering at Intermediate Energies and Three Nucleon Forces  

NASA Astrophysics Data System (ADS)

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with polarized deuterons beams at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers in deuteron-proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with the Tucson-Melbourne'99, and UrbanaIX three nucleon forces.

Sekiguchi, K.; Okamura, H.; Wada, Y.; Miyazaki, J.; Taguchi, T.; Gebauer, U.; Dozono, M.; Kawase, S.; Kubota, Y.; Lee, C. S.; Maeda, Y.; Mashiko, T.; Miki, K.; Sakaguchi, S.; Sakai, H.; Sakamoto, N.; Sasano, M.; Shimizu, Y.; Takahashi, K.; Tang, R.; Uesaka, T.; Wakasa, T.; Yako, K.

370

Complete Set of Deuteron Analyzing Powers for dp Elastic Scattering at Intermediate Energies and Three Nucleon Forces  

NASA Astrophysics Data System (ADS)

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with the polarized deuteron beam at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers in deuteron-proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with the Tucson-Melbourne'99, and UrbanaIX three nucleon forces.

Sekiguchi, K.; Okamura, H.; Wada, Y.; Miyazaki, J.; Taguchi, T.; Gebauer, U.; Dozono, M.; Kawase, S.; Kubota, Y.; Lee, C. S.; Maeda, Y.; Mashiko, T.; Miki, K.; Sakaguchi, S.; Sakai, H.; Sakamoto, N.; Sasano, M.; Shimizu, Y.; Takahashi, K.; Tang, R.; Uesaka, T.; Wakasa, T.; Yako, K.

2014-08-01

371

Measurement of the Tensor Analyzing Powers T20 and T21 in Elastic Electron-Deuteron Scattering  

SciTech Connect

The tensor analyzing power components T{sub 20} and T{sub 21} have been measured in elastic electron-deuteron scattering at the 2 GeV electron storage ring VEPP-3, Novosibirsk, in a four-momentum transfer range from 8.4 to 21.6 fm{sup -2}. A new polarized internal gas target with an intense cryogenic atomic beam source was used. The new data determine the deuteron form factors GC and GQ in an important range of momentum transfer where the first node of the deuteron monopole charge form factor is located. The new results are compared with previous data and with some theoretical predictions.

D. M. Nikolenko; H. Arenhoevel; L. M. Barkov; S. L. Belostotsky; V. F. Dmitriev; M. V. Dyug; R. Gilman; R. J. Holt; L. G. Isaeva; C. W. de Jager; E. R. Kinney; R. S. Kowalczyk; B. A. Lazarenko; A. Yu. Loginov; S. I. Mishnev; V. V. Nelyubin; A. V. Osipov; D. H. Potterveld; I. A. Rachek; R. Sh. Sadykov; Yu. V. Shestakov; A. A. Sidorov; V. N. Stibunov; D. K. Toporkov; V. V. Vikhrov; H. de Vries; and S. A. Zevakov

2003-02-01

372

The proton conducting electrolyte BaTi0.5In0.5O2.75: determination of the deuteron site and its local environment  

NASA Astrophysics Data System (ADS)

Deuterated BaTi0.5In0.5O2.75 has been studied with neutron total (Bragg plus diffuse) scattering data, using both the Rietveld refinement method and the reverse Monte Carlo (RMC) modelling technique, to investigate the preferred proton site and its local structural environment. The Rietveld analysis shows an excellent fit between experimental data and a long-range cubic description of the BaTi0.5In0.5O2.53(OD)0.44 perovskite structure containing a statistical distribution of Ti and In ions at the centre of regular (Ti/In)O6 octahedra. However, an RMC analysis of the data reveals substantial local structural features that reflect limitations of the Rietveld method for studies of this type. The Ti-O and In-O pair distribution functions given by the RMC analysis are markedly different from each other, with average Ti-O and In-O bond distances of 2.035 Å and 2.159 Å, respectively. The InO6 octahedra are regular in shape whereas the TiO6 octahedra are distorted. The average O-D bond distance is roughly 0.96 Å, and the preferred deuteron sites have a second nearest oxygen distance of 2.13 Å, which confirms localized tilting of the deuteron and indicates a substantial degree of hydrogen bonding. The impact of octahedral distortion and hydrogen bonding on the proton conduction mechanism is discussed.

Norberg, Stefan T.; Rahman, Seikh M. H.; Hull, Stephen; Knee, Christopher S.; Eriksson, Sten G.

2013-11-01

373

Direct processes in 54-MeV Li-7 breakup reactions on C-12 and Au-197 targets, and the extraction of astrophysical cross sections  

NASA Astrophysics Data System (ADS)

Strong direct processes were observed for elastic breakup in 54-MeV Li-7 + C-12, Au-197 reactions. In the case of C-12, the observed Li-7 to alpha + t direct-breakup yield was significantly larger than predicted by a Coulomb-breakup calculation, indicating the importance of the nuclear field. For Au-197, final-state interactions produced a strong distortion in the fragment energy spectra, as well as a modulation of the coincidence efficiency for different detector geometries. Such Coulomb effects are found to severely complicate the extraction of radiative-capture cross sections from direct-breakup data.

Gazes, S. B.; Mason, J. E.; Roberts, R. B.; Teichmann, S. G.

1992-01-01

374

Two-nucleon systems in a finite volume. II. S13-D13 coupled channels and the deuteron  

SciTech Connect

The energy spectra of two nucleons in a cubic volume provide access to the two phase shifts and one mixing angle that define the S matrix in the S13-D13 coupled channels containing the deuteron. With the aid of recently derived energy quantization conditions for such systems, and the known scattering parameters, these spectra are predicted for a range of volumes. It is found that extractions of the infinite-volume deuteron binding energy and leading scattering parameters, including the S-D mixing angle at the deuteron pole, are possible from lattice QCD calculations of two-nucleon systems with boosts of |P|?2?/L{radical}3 in volumes with 10??fm?L?14??fm. The viability of extracting the asymptotic D/S ratio of the deuteron wave function from lattice QCD calculations is discussed.

Briceno, Raul [JLAB; Davoudi, Zohreh [Washington U.; Luu, Thomas C. [Forschungszentrum Jülich; Savage, Martin J. [Washington U.

2013-12-01

375

Radiative Capture of Neutrons and Deuterons Into CARBON-13: Evidence for a Secondary Doorway State Effect  

NASA Astrophysics Data System (ADS)

Differential cross sections were measured at a detector angle of 90(DEGREES) in the lab for the ('12)C(n,(gamma)(,0))('13)C reaction at 19 incident neutron energies between 6.5 and 18.5 MeV. This energy region spans the pygmy and T(,<) giant dipole resonances in ('13)C. Angular distributions of cross section were measured for this reaction at 7 incident neutron energies between 12.0 and 18.5 MeV. Angular distributions of vector analyzing power were measured for the ('12)C((')n,(gamma)(,0))('13)C reaction at 4 incident neutron energies between 12.0 and 18.2 MeV, analyzing powers were measured at 125(DEGREES) neutron energies of 15.4, 17.4, and 18.8 MeV. The angular distributions show a rapid energy dependence just below the peak of the giant dipole resonance. This energy dependent structure in the angular distributions occurs at the same excitation energy as a resonance in the ('11)B(d,(gamma)(,0))('13)C reaction. A study of the deuteron capture reaction in this energy region was therefore under- taken. The 90(DEGREES) differential cross sections were measured for the ('11)B(d,(gamma)(,0))('13)C reaction at 11 deuteron beam energies between 1.65 and 3.50 MeV. Angular distributions of cross section were measured at deuteron beam energies of 1.6, 1.8, 2.0, and 4.0 MeV. Angular distributions of vector and tensor (T(,20)((THETA))) analyzing power were measured at deuteron beam energies of 2.0 and 4.0 MeV, with 55(DEGREES) and 125(DEGREES) vector analyzing powers being measured at 1.6 and 1.8 MeV. Both data sets were fit simultaneously using a formalism which described the ('11)B(d,(gamma)(,0))('13)C resonance as a secondary doorway state, with the T(,<) giant dipole resonance (seen through the neutron capture data) being a primary doorway state. The data were well described by this fit, most notably the rapid energy dependence in the neutron capture angular distributions. A shell model calculation of the expected strength of this interaction agreed well with the strength found by fitting the data. It was found to be possible to describe the deuteron capture angular distributions (the doorway state formalism leaves these independent of the rest of the analysis) fairly well using a simple "deuteron cluster" model of the ('13)C ground state.

August, Robert Andrew, Jr.

376

Preservation and control of the proton and deuteron polarizations in the proposed electron-ion collider at Jefferson Lab  

SciTech Connect

We propose a scheme of preserving the proton and deuteron beam polarizations during acceleration and storage in the proposed electron-ion collider at Jefferson Lab. This scheme allows one to provide both the longitudinal and transverse polarization orientations of the proton and deuteron beams at the interaction points of the figure-8 ion collider ring. We discuss questions of matching the polarization direction at all stages of the beam transport including the pre-booster, large booster and ion collider ring.

Kondratenko, Anatoliy [Scientific and Technical Laboratory Zaryad, Novosibirsk (Russian Federation); Derbenev, Yaroslav S. [JLAB, Newport News, VA (United States); Filatov, Yury [Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Lin, Fanglei [JLAB, Newport News, VA (United States); Morozov, Vasiliy [JLAB, Newport News, VA (United States); Kondratenko, M. A. [Scientific and Technical Laboratory Zaryad, Novosibirsk (Russian Federation); Zhang, Yuhong [JLAB, Newport News, VA (United States)

2014-01-01

377

Measurement of the deuteron structure function F2 in the resonance region and evaluation of its moments  

Microsoft Academic Search

Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F2 with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasielastic peak up to the invariant mass of the final-state hadronic system W~=2.7 GeV with four-momentum transfers Q2 from 0.4 to

M. Osipenko; G. Ricco; S. Simula; M. Battaglieri; M. Ripani; G. Adams; P. Ambrozewicz; M. Anghinolfi; B. Asavapibhop; G. Asryan; G. Audit; H. Avakian; H. Bagdasaryan; N. Baillie; J. P. Ball; N. A. Baltzell; S. Barrow; V. Batourine; K. Beard; I. Bedlinskiy; M. Bektasoglu; M. Bellis; N. Benmouna; A. S. Biselli; B. E. Bonner; S. Bouchigny; S. Boiarinov; R. Bradford; D. Branford; W. K. Brooks; S. Bültmann; V. D. Burkert; C. Butuceanu; J. R. Calarco; S. L. Careccia; D. S. Carman; A. Cazes; S. Chen; P. L. Cole; A. Coleman; P. Corvisiero; D. Cords; D. Crabb; J. P. Cummings; E. de Sanctis; R. Devita; P. V. Degtyarenko; H. Denizli; L. Dennis; A. Deur; K. V. Dharmawardane; C. Djalali; G. E. Dodge; J. Donnelly; D. Doughty; P. Dragovitsch; M. Dugger; S. Dytman; O. P. Dzyubak; H. Egiyan; K. S. Egiyan; L. Elouadrhiri; A. Empl; P. Eugenio; R. Fatemi; G. Fedotov; R. J. Feuerbach; T. A. Forest; H. Funsten; M. Garçon; G. Gavalian; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; C. I. O. Gordon; R. W. Gothe; K. A. Griffioen; M. Guidal; M. Guillo; N. Guler; L. Guo; V. Gyurjyan; C. Hadjidakis; R. S. Hakobyan; J. Hardie; D. Heddle; F. W. Hersman; K. Hicks; I. Hleiqawi; M. Holtrop; J. Hu; M. Huertas; C. E. Hyde-Wright; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; M. M. Ito; D. Jenkins; H. S. Jo; K. Joo; H. G. Juengst; J. D. Kellie; M. Khandaker; K. Y. Kim; W. Kim; A. Klein; F. J. Klein; A. V. Klimenko; M. Klusman; M. Kossov; L. H. Kramer; V. Kubarovsky; J. Kuhn; S. E. Kuhn; J. Lachniet; J. M. Laget; J. Langheinrich; D. Lawrence; T. Lee; Ji Li; A. C. S. Lima; K. Livingston; K. Lukashin; J. J. Manak; C. Marchand; S. McAleer; B. McKinnon; J. W. C. McNabb; B. A. Mecking; S. Mehrabyan; J. J. Melone; M. D. Mestayer; C. A. Meyer; K. Mikhailov; R. Minehart; M. Mirazita; R. Miskimen; V. Mokeev; L. Morand; S. A. Morrow; J. Mueller; G. S. Mutchler; P. Nadel-Turonski; J. Napolitano; R. Nasseripour; G. Nefedov; S. Niccolai; G. Niculescu; I. Niculescu; B. B. Niczyporuk; R. A. Niyazov; M. Nozar; G. V. O'Rielly; A. I. Ostrovidov; E. Pasyuk; S. A. Philips; J. Pierce; N. Pivnyuk; D. Pocanic; O. Pogorelko; E. Polli; S. Pozdniakov; B. M. Preedom; J. W. Price; Y. Prok; D. Protopopescu; L. M. Qin; B. A. Raue; G. Riccardi; B. G. Ritchie; F. Ronchetti; G. Rosner; P. Rossi; D. Rowntree; P. D. Rubin; F. Sabatié; C. Salgado; J. P. Santoro; V. Sapunenko; R. A. Schumacher; V. S. Serov; Y. G. Sharabian; J. Shaw; A. V. Skabelin; E. S. Smith; L. C. Smith; D. I. Sober; A. Stavinsky; S. S. Stepanyan; B. E. Stokes; P. Stoler; S. Strauch; R. Suleiman; M. Taiuti; S. Taylor; D. J. Tedeschi; U. Thoma; R. Thompson; A. Tkabladze; L. Todor; C. Tur; M. Ungaro; M. F. Vineyard; A. V. Vlassov; L. B. Weinstein; D. P. Weygand; M. Williams; E. Wolin; M. H. Wood; A. Yegneswaran; J. Yun; L. Zana; J. Zhang

2006-01-01

378

The influence of the deviation from the equilibrium deuteron distribution on the neutron spectra in linear pinch geometries  

NASA Astrophysics Data System (ADS)

In order to analyze the influence of the deviation from the equilibrium distribution of the fast deuterons on the neutron spectrum, the limiting case, corresponding to a two dimensional monoenergetic deuteron distribution, was studied. The appearance of a pronounced peak in the side-on spectra at neutron energy = 2.5 MeV is noted. There is good agreement between theory and experiment, if relaxation processes are taken into account.

Deutsch, R.; Herold, H.; Kaeppeler, H. J.; Schmidt, H.

1982-07-01

379

Deuteron frozen-spin- polarized target for nd experiments at the VdG accelerator of Charles University  

NASA Astrophysics Data System (ADS)

A frozen-spin- polarized deuteron target cooled by the 3He/ 4He dilution refrigerator is described. Fully deuterated 1,2-propanediol was used as a target material. Deuteron vector polarization about 40% was obtained for the target in the shape of a cylinder of 2-cm diameter and 6-cm length. The target is intended for a study of 3N interactions at the polarized neutron beam generated by the Van de Graaff accelerator at the Charles University in Prague.

Borisov, N. S.; Bazhanov, N. A.; Belyaev, A. A.; Brož, J.; ?erný, J.; Doležal, Z.; Fedorov, A. N.; Gurevich, G. M.; Ivanov, M. P.; Kodyš, P.; Kubík, P.; Kuzmin, E. S.; Lazarev, A. B.; Lehar, F.; Lukhanin, O. O.; Matafonov, V. N.; Neganov, A. B.; Pisarev, I. L.; Švejda, J.; Shilov, S. N.; Usov, Yu. A.; Wilhelm, I.

2008-08-01

380

Dynamics and breakup of a contracting liquid filament  

NASA Astrophysics Data System (ADS)

Contraction of a filament of an incompressible Newtonian liquid in a passive ambient fluid is studied computationally to provide insights into the dynamics of satellite drops created during drop formation. This free boundary problem, which is composed of the Navier Stokes system and the associated initial and boundary conditions that govern the evolution in time of the filament shape and the velocity and pressure fields within it, is solved by the method of lines incorporating the finite element method for spatial discretization. The finite element algorithm developed here utilizes an adaptive elliptic mesh generation technique that is capable of tracking the dynamics of the filament up to the incipience of pinch-off without the use of remeshing. The correctness of the algorithm is verified by demonstrating that its predictions accord with (a) previously published results of Basaran (1992) on the analysis of finite-amplitude oscillations of viscous drops, (b) simulations of the dynamics of contracting filaments carried out with the well-benchmarked algorithm of Wilkes et al. (1999), and (c) scaling laws governing interface rupture and transitions that can occur from one scaling law to another as pinch-off is approached. In dimensionless form, just two parameters govern the problem: the dimensionless half-length L_o and the Ohnesorge number Oh which measures the relative importance of viscous force to capillary force. Regions of the parameter space are identified where filaments (a) contract to a sphere without breaking into multiple droplets, (b) break via the so-called endpinching mechanism where daughter drops pinch-off from the ends of the main filament, and (c) break after undergoing a series of complex oscillations. Predictions made with the new algorithm are also compared to those made with a model based on the slender-jet approximation. A region of the parameter space is found where the slender-jet approximation fares poorly, and its cause is elucidated by examination of the vorticity dynamics and flow fields within contracting filaments.

Notz, Patrick K.; Basaran, Osman A.

2004-08-01

381

Mechanisms in knockout reactions  

NASA Astrophysics Data System (ADS)

We report on the first detailed study of the mechanisms involved in knockout reactions, via a coincidence measurement of the residue and fast proton in one-proton knockout reactions, using the S800 spectrograph in combination with the HiRA detector array at the NSCL. Results on the reactions ^9Be(^9C,^8B+X)Y and ^9Be(^8B,^7Be+X)Y are presented. They are compared with theoretical predictions for both the diffraction (elastic breakup) and stripping (inelastic breakup) reaction mechanisms, as calculated in the eikonal model. The data shows a clear distinction between the two reaction mechanisms, and the observed respective proportions are very well reproduced by the reaction theory. This agreement supports the results of knockout reaction analyses and their applications to the spectroscopy of rare isotopes. In particular, this add considerable support to the use of the eikonal model as a quantitative tool, able, for example, to determine single-particle spectroscopic strengths in rare isotopes.

Bazin, D.; Charity, R. J.; de Souza, R. T.; Famiano, M. A.; Gade, A.; Henzl, V.; Henzlova, D.; Hudan, S.; Lee, J.; Lukyanov, S.; Lynch, W. G.; McDaniel, S.; Mocko, M.; Obertelli, A.; Rogers, A. M.; Sobotka, L. G.; Terry, J. R.; Tostevin, J. A.; Tsang, M. B.; Wallace, M. S.

2009-10-01

382

Evolution of Raindrop Size Distribution by Coalescence, Breakup, and Evaporation: Theory and Observations.  

NASA Astrophysics Data System (ADS)

The evolution of raindrop size distribution by coalescence, collisional breakup, and evaporation is studied using the Low and List parameterization for collisions. The authors consider two models of the development of raindrop size distribution; model 1 is a spatially homogeneous, time-dependent model, and model 2 is a ID (vertical) time-dependent model. The authors present the governing equations for the drop size distribution, balance equations for the rainwater content and rainfall rate, and scaling relationships. The authors demonstrate that the two models are intimately related. For model 1, the authors find that under the action of coalescence and breakup the size distribution attains a steady equilibrium form with three peaks at small drop sizes and an exponential tail at large drop sizes with a slope of approximately 65 cm1. Under the action of coalescence, breakup, and evaporation. the evolution of a size distribution with a high enough rainwater content can be divided into two phases. In the initial phase, the evolution is collision controlled and the distribution evolves rapidly to approximate the shape of the equilibrium distribution without evaporation. The second phase starts after the rainwater content has been sufficiently reduced by evaporation. In this phase the evolution is evaporation controlled, the peaks at small drop sizes are smoothed, but the tail of the distribution remains exponential and its slope changes only slowly with time. In model 2, with a steady input of raindrops at the top of the rain shaft, a steady distribution is attained at any height after the lapse of a sufficiently long time. After a sufficient distance of fall, the steady distribution becomes approximately invariant with distance of fall and very close to the equilibrium distribution of model 1. With evaporation also occurring, the evolution is similar to that for model 1, with distance of fall taking on the role of time of evolution. A comparison of the results of the calculations with observed raindrop size distributions, at high rainfall rates, supports the idea that the observed distributions are in or near collisional equilibrium. However, the slope (20-25 cm1) of the tail of the observed distributions is much smaller than the slope (65 cm1) of the computed equilibrium distribution. This discrepancy suggests that either the Low and List parameterization is greatly overestimating drop breakup and/or the number of fragments formed by collisional breakup, or processes other than coalescence, breakup, and evaporation are strongly controlling the observed raindrop size distributions. Another possible factor contributing to the discrepancy may be the averaging of observed raindrop size distributions over considerable periods of time. It is recommended that in future observations attempts be made to obtain reliable drop size distributions in much shorter periods of time.

Hu, Zaillang; Srivastava, R. C.

1995-05-01

383

Probing the high momentum component of the deuteron at high Q^2.  

SciTech Connect

The {sup 2}H(e,e'p) cross section at a momentum transfer of 3.5 (GeV/c){sup 2} was measured over a kinematical range that made it possible to study this reaction for a set of fixed missing momenta as a function of the neutron recoil angle {theta}{sub nq} and to extract missing momentum distributions for fixed values of {theta}{sub nq} up to 0.55 GeV/c. In the region of 35{sup o} {le} {theta}{sub nq} {le} 45{sup o} recent calculations, which predict that final state interactions are small, agree reasonably well with the experimental data. Therefore these experimental reduced cross sections provide direct access to the high momentum component of the deuteron momentum distribution in exclusive deuteron electro-disintegration.

Boeglin, Werner; Ambrozewicz, Pawel; Aniol, Konrad; Arrington, John; Batigne, Guillaume; Bosted, Peter; Camsonne, Alexandre; Chang, C; Chen, Jian-Ping; Choi, Seonho; Deur, Alexandre; Epstein, Martin; Finn, John; Frullani, Salvatore; Furget, Christophe; Garibaldi, Franco; Gayou, Olivier; Gilman, Ronald; Hansen, Jens-Ole; Hayes, David; Higinbotham, Douglas; Hinton, Wendy; Hyde, Charles; Ibrahim, Hassan; De Jager, Cornelis; Jiang, Xiaodong; Jones, Mark; Kaufman, Lisa; Klein, Andreas; Kox, Serge; Kramer, Laird; Kumbartzki, Gerfried; Laget, Jean; LeRose, John; Lindgren, Richard; Margaziotiz, Demetrius; Markowitz, Pete; McCormick, Kathy; Meziani, Zein-Eddine; Michaels, Robert; Milbrath, Brian; Mitchell, Joseph; Monaghan, Peter; Moteabbed, Maryam; Moussiegt, Pierre; Nasseripour, Rakhsha; Paschke, Kent; Perdrisat, Charles; Piasetzky, Eliazer; Punjabi, Vina; Qattan, Issam; Quemener, Gilles; Ransome, Ronald; Raue, Brian; Real, Jean-Sebastien; Reinhold, Joerg; Reitz, Bodo; Roche, Rikki; Roedelbronn, Michael; Saha, Arunava; Slifer, Karl; Solvignon-Slifer, Patricia; Sulkosky, Vincent; Ulmer, Paul; Voutier, Eric; Weinstein, Lawrence; Wojtsekhowski, Bogdan

2011-12-01

384

Nuclear effects in the proton-deuteron Drell-Yan process  

SciTech Connect

We compute the nuclear corrections to the proton-deuteron Drell-Yan cross section for inclusive dilepton production, which, when combined with the proton-proton cross section, is used to determine the flavor asymmetry in the proton sea, dbar - ubar. In addition to nuclear smearing corrections that are known to be important at large values of the nucleon's parton momentum fraction x_N, we also consider dynamical off-shell nucleon corrections associated with the modifications of the bound nucleon structure inside the deuteron, which we find to be significant at intermediate and large x_N values. We also provide estimates of the nuclear corrections at kinematics corresponding to existing and planned Drell-Yan experiments at Fermilab and J-PARC which aim to determine the dbar/ubar ratio for x < 0.6.

Ehlers, Peter J. [Univ. Washington; Accardi, Alberto [Hampton U., JLAB; Brady, Lucas T.; Melnitchouk, Wally [JLAB

2014-07-01

385

Charge exchange in the relaxation of a deuteron beam in a two-component tokamak  

NASA Astrophysics Data System (ADS)

A stability analysis is carried out for a beam of fast ions in the plasma of a two-component tokamak, of the type described by Furth (1975), in which the interaction between a deuteron beam and the tritium of the plasma filament plays a major part in the nuclear reactions. The influence of charge-exchange on the relaxation of the deuteron beam in a tokamak with longitudinal injection is examined. It is shown that charge exchange may play a major role, even at a relatively low neutral-deuterium density, since charge exchange sustains an anisotropic distribution of the beam with respect to velocity. The anisotropic distribution leads to a beam-Alfven instability and a marked acceleration of the beam relaxation process.

Gureev, K. G.; Cheremnykh, O. K.

1980-01-01

386

Space-time study of double scattering in hadron deuteron collisions  

SciTech Connect

A space-time picture of double scattering in the deuteron (those events where both the neutron and proton interact with the incoming hadron) is developed. We work in the deuteron rest frame using the assumption that processes involving large virtual masses are damped. For the general case, the process is shown to consist of sequential scatterings, while for large momenta, we may, due to Lorentz contraction, neglect the separation between neutron and proton, and the Abramovskii, Gribov, and Kancheli cutting rules are derived. We then model the process with the Mandelstam diagram and verify the previous results by explicit calculation. A numerical estimate is then made of the size of the effect and a comparison with experimental data is made.

Rogers, E.O.

1981-01-01

387

Measurement of 230Pa and 186Re Production Cross Sections Induced by Deuterons at Arronax Facility  

NASA Astrophysics Data System (ADS)

A dedicated program has been launched on production of innovative radionuclides for PET imaging and for ?- and ? targeted radiotherapy using proton or ? particles at the ARRONAX cyclotron. Since the accelerator is also able to deliver deuteron beams up to 35 MeV, we have reconsidered the possibility of using them to produce medical isotopes. Two isotopes dedicated to targeted therapy have been considered: 226Th, a decay product of 230Pa, and 186Re. The production cross sections of 230Pa and 186Re, as well as those of the contaminants created during the irradiation, have been determined by the stacked-foil technique using deuteron beams. Experimental values have been quantified using a referenced cross section. The measured cross sections have been used to determine expected production yields and compared with the calculated values obtained using the Talys code with default parameters.

Duchemin, Charlotte; Guertin, Arnaud; Metivier, Vincent; Haddad, Ferid; Michel, Nathalie

2014-02-01

388

SOCIT4 collisional-breakup test data analysis: with shape and materials  

NASA Astrophysics Data System (ADS)

The Satellite Orbital-Debris Characterization Impact Test SOCIT series was a set of four hypervelocity impact tests conducted under a U S Department of Defense DoD program in 1991 through 1992 The common testing procedure of the set was to launch a small projectile at hypervelocity towards a large target in an impact chamber The last of the four tests SOCIT4 targeted a flight-ready U S Transit navigation satellite yielding collision fragments in the size regime of one millimeter through tens of centimeters A subset of the fragments was weighed measured and tabulated The derived area-to-mass vs size distributions have been used in the NASA breakup models dated 1998 and 2001 current model This paper revisits the SOCIT4 data set and explores in detail the fragment material shape and pickup position relationships The intent of this study is not only to gain an understanding of the collisional-breakup process of this particular payload but also to determine how these data may apply to other breakups What emerges from the study first is a clear distinction in fragment area-to-mass between primarily metal heavy and primarily non-metal light fragments Metal fragments which are dominated by aluminum follow the characteristic curve of increasing area-to-mass with decreasing size objects move from the character of large irregular chards to that of small solid spheroids Non-metal fragments dominated by phenolic plastic also move towards solid spheroids as their sizes decrease But unlike the metals

Krisko, P. H.; Horstman, M.; Fudge, M. L.

389

Field-cooled and zero-field-cooled dielectric susceptibility in deuteron glasses  

Microsoft Academic Search

The temperature dependence of the field-cooled and zero-field cooled static dielectric susceptibilities of the deuteron glass Rb0.4(ND4)0.6D2PO4 has been determined. Whereas above the freezing temperature Tf the two susceptibilities are equal, a splitting of the two branches as well as a remanent polarization is observed below Tf. The fact that this splitting takes place demonstrates the occurrence of a freezing

A. Levstik; C. Filipi; Z. Kutnjak; I. Levstik; R. Pirc; B. Tadic; R. Blinc

1991-01-01

390

Recoil-Proton Polarization in High-Energy Deuteron Photodisintegration with Circularly Polarized Photons  

SciTech Connect

We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.

X. Jiang; J. Arrington; F. Benmokhtar; A. Camsonne; J. P. Chen; S. Choi; E. Chudakov; F. Cusanno; A. Deur; D. Dutta; F. Garibaldi; D. Gaskell; O. Gayou; R. Gilman; C. Glashauser; D. Hamilton; O. Hansen; D. W. Higinbotham; R. J. Holt; C. W. de Jager; M. K. Jones; L. J. Kaufman; E. R. Kinney; K. Kramer; L. Lagamba; R. de Leo; J. Lerose; D. Lhuillier; R. Lindgren; N. Liyanage; K. McCormick; Z.-E. Meziani; R. Michaels; B. Mof?t; P. Monaghan; S. Nanda; K. D. Paschke; C. F. Perdrisat; V. Punjabi; I. A. Qattan; R. D. Ransome; P. E. Reimer; B. Reitz; A. Saha; E. C. Schulte; R. Sheyor; K. Slifer; P. Solvignon; V. Sulkosky; G. M. Urciuoli; E. Voutier; K. Wang; K. Wijesooriya; B. Wojtsekhowski; and L. Zhu

2007-05-01

391

Dissecting deuteron Compton scattering I: The observables with polarised initial states  

NASA Astrophysics Data System (ADS)

A complete set of linearly independent observables in Compton scattering with arbitrarily polarised real photons off an arbitrarily polarised spin-1 target is introduced, for the case that the final-state polarisations are not measured. Adopted from the one widely used, e.g., in deuteron photo-dissociation, it consists of 18 terms: the unpolarised cross section, the beam asymmetry, 4 target asymmetries and 12 asymmetries in which both beam and target are polarised. They are expressed by the helicity amplitudes and —where available— related to observables discussed by other authors. As application to deuteron Compton scattering, their dependence on the (isoscalar) scalar and spin dipole polarisabilities of the nucleon is explored in Chiral Effective Field Theory with dynamical ?(1232) degrees of freedom at order e 2 ? 3. Some asymmetries are sensitive to only one or two dipole polarisabilities, making them particularly attractive for experimental studies. At a photon energy of 100 MeV, a set of 5 observables is identified from which one may be able to extract the spin polarisabilities of the nucleon. These are experimentally realistic but challenging and mostly involve tensor-polarised deuterons. Relative to Compton scattering from a nucleon, sensitivity to the "mixed" spin polarisabilities ? E1 M2 and ? M1 E2 is increased because of the interference with the D wave component of the deuteron and with its pion-exchange current. An interactive Mathematica 9.0 notebook with results for all observables at photon energies up to 120 MeV is available from hgrie@gwu.edu.

Grießhammer, Harald W.

2013-08-01

392

Calculations of Double Differential Deuteron Emission Cross Sections at 62 MeV Proton Induced Reactions  

NASA Astrophysics Data System (ADS)

In this study, double differential deuteron emission cross sections for 27Al, 54,56Fe, 197Au, 208Pb and 209Bi target nuclei have been calculated by the TALYS code at 62 MeV proton energy. The use of TALYS involved calculations by the pre-equilibrium exciton model and the Hauser-Feshbach model. The calculated double differential cross sections have been compared with the experimental data taken from the literature.

Aydin, A.; Sarpun, I. H.; Kaplan, A.; Tel, E.

2013-06-01

393

Recoil-proton polarization in high-energy deuteron photodisintegration with circularly polarized photons.  

PubMed

We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance. PMID:17501566

Jiang, X; Arrington, J; Benmokhtar, F; Camsonne, A; Chen, J P; Choi, S; Chudakov, E; Cusanno, F; Deur, A; Dutta, D; Garibaldi, F; Gaskell, D; Gayou, O; Gilman, R; Glashauser, C; Hamilton, D; Hansen, O; Higinbotham, D W; Holt, R J; de Jager, C W; Jones, M K; Kaufman, L J; Kinney, E R; Kramer, K; Lagamba, L; de Leo, R; Lerose, J; Lhuillier, D; Lindgren, R; Liyanage, N; McCormick, K; Meziani, Z-E; Michaels, R; Moffit, B; Monaghan, P; Nanda, S; Paschke, K D; Perdrisat, C F; Punjabi, V; Qattan, I A; Ransome, R D; Reimer, P E; Reitz, B; Saha, A; Schulte, E C; Sheyor, R; Slifer, K; Solvignon, P; Sulkosky, V; Urciuoli, G M; Voutier, E; Wang, K; Wijesooriya, K; Wojtsekhowski, B; Zhu, L

2007-05-01

394

Deuteron spin structure functions in the resonance and deep inelastic scattering regions  

SciTech Connect

We derive relations between spin-dependent nuclear and nucleon g1 and g2 structure functions within the nuclear impulse approximation, which are valid at all Q^2, and in both the resonance and deep inelastic regions. We apply the formalism to the specific case of the deuteron, which is often used as a source of neutron structure information, and compare the size of the nuclear corrections calculated using exact kinematics and using approximations applicable at large Q^2.

S.A. Kulagin; W. Melnitchouk

2008-01-01

395

The relativistic impulse approximation for the exclusive electrodisintegration of the deuteron  

E-print Network

The electrodisintegration of the deuteron in the frame of the Bethe-Salpeter approach with a separable kernel of the nucleon-nucleon interaction is considered. This conception keeps the covariance of a description of the process. A comparison of relativistic and nonrelativistic calculations is presented. The factorization of the cross section of the reaction in the impulse approximation is obtained by analytical calculations. It is shown that the photon-neutron interaction plays an important role.

S. G. Bondarenko; V. V. Burov; E. P. Rogochaya; A. A. Goy

2006-12-15

396

Implications of Plume Head Feeding of Asthenosphere for Continental Breakup and Convergence  

NASA Astrophysics Data System (ADS)

A global layer of asthenosphere that is hotter and more buoyant that deeper mantle can explain a range of observations. For example, the spreading rate dependent thinning of asthenosphere can explain why the fastest spreading center, the East Pacific Rise, is also the deepest very large spreading center. Models using the same asthenospheric properties also reproduce the even greater depths of the Australian-Antarctic Discordance. This result is due to restricted flow around diverging thick cratonic lithosphere. Mantle plumes are often assumed to be the source of hot asthenosphere. Plumes are also considered as the source for ocean island basalts (OIBs). If the asthenosphere is widespread it would also be the source region for mid-ocean ridge basalts (MORBs). Since OIB and MORB have very different major, trace and isotopic compositions it is hard to reconcile plumes as the source for both. However, the basalts in large Igneous provinces (LIPs) are similar to MORBs. Thus, it is possible that the source of LIPs is also the source of more widespread hot asthenosphere. The breakup of continents is strongly correlated with massive volcanism in LIPs. Diapiric upwelling of hot mantle plume heads is the widely accepted mechanism to produce both the regional uplift and the large volumes of basalt needed to allow continental splitting. Previous estimates of plume head volumes were based on the assumption that the basalt results from partial melting of the entire plume head to a moderate fraction. However, the low-density of the residue of mantle melting may prevent the deeper parts of the plume head from ascending to shallow depths where it can partially melt. Therefore the volume of plume heads may be sufficient to supply hot mantle to the entire asthenosphere. Just as localized thickening of the asthenosphere during a plume head event may supply the uplift-related force to drive magma-assisted rifting, the thinning of a buoyant layer of asthenosphere may provide much of the force needed to thicken crust in mountain belts. Subduction can drive such thinning as asthenosphere freezes onto the top of a slab and is dragged into the deep mantle. However, sufficient asthenospheric thinning to build high mountains can only happen if the region of asthenosphere thinning is walled in by thick cratonic lithosphere on one side and by a laterally continuous slab curtain on the other side. Moderate to fast rate subduction with such a lithospheric configuration has to persist for tens of Ma to produce high mountains. Geologic data is consistent with such long periods of subduction before the onset of crustal convergence in for the Larimide, Andean and Tibetan orogenies. Processes such as plate spreading and cooling act to diminish the amount of hot asthenosphere in a region. If hot asthenosphere is supplied by infrequent plume head events then this may lead to gradual changes in spreading center depths. Such thinning of buoyant asthenosphere under a large region could put a spreading center into compression relative to other ridges and might promote initiation of subduction.

Buck, W. R.

2012-12-01

397

Assessment of the consequences of the Fengyun-1C breakup in low Earth orbit  

NASA Astrophysics Data System (ADS)

On 11 January 2007, the 880 kg (958 kg at launch) weather spacecraft Fengyun-1C, launched on 10 May 1999 into a sun-synchronous orbit with a CZ-4B booster from the Taiyuan Satellite Launch Center, was destroyed over central China as a result of the first successful Chinese anti-satellite weapon test. It was carried out with a direct ascent interception with a kinetic energy kill vehicle launched by an SC-19 missile, fired from a mobile ground platform close to the Xichang Satellite Launch Center. While the technical details of the test, probably the third attempt, and the characteristics of the weapon used remain shrouded in secrecy, the intentional breakup of the aging weather spacecraft, fully functional until 2005, produced a huge amount of debris in one of the orbital regimes already most affected by past fragmentation events. At present, the US Space Surveillance Network has identified about 2600 objects, typically larger than 10 cm, but the fragments larger than 1 cm may be more than 100,000. After two decades of substantial international progress in the field of orbital debris mitigation, in order to preserve the low Earth and geosynchronous environments for future space missions, the Fengyun-1C destruction represented a serious turnabout. In fact, it abruptly increased by approximately 20% the number of cataloged debris in orbit. To give a rough idea of the impact of this single event on the circumterrestrial environment, it is sufficient to realize that about 15 years of global space activity - including failures and accidental breakups - had been needed to increase, by a comparable amount, the number of cataloged debris in orbit to the level observed before the Chinese anti-satellite test. The purpose of this presentation is to assess the impact of the debris cloud generated by the Fengyun-1C breakup on the low Earth environment. The anti-satellite test was carried out at an altitude of about 863 km, spreading the cataloged fragments between 200 and 4000 km, with maximum concentration around the breakup height. The environmental impact was particularly significant in all the altitude range between 700 and 1000 km, where the debris density due to past space activities was already at worrisome levels. Considering the inclination, nearly polar, and the height of the target, such a deliberate act of debris generation was therefore one of worst conceivable with current technology and its consequences will unfortunately be felt for many decades.

Pardini, Carmen

398

Comparison of axial and radial electron beam-breakup transit-time oscillators  

SciTech Connect

Comparison of two configurations of a novel high-power microwave generator is presented in this article. Coupling the beam-breakup instability with the transit-time effect of the electron beam in the cavity, rapid energy exchange between the electrons and cavity modes can occur. The dominant cavity modes in the axial and radial configurations are different but their growth rates are comparable. We found that the radial configuration can have a beam impedance less than 10 {Omega} and therefore more suitable for low-voltage and high power operation. Good agreements have been obtained between linear theory and simulation for both configurations.

Kwan, T.J.T. [Los Alamos National Lab., NM (United States); Mostrom, M.A. [Mission Research Corporation, Albuquerque, NM (United States)

1995-08-01

399

An Attempt to Observe Debris from the Breakup of a Titan 3C-4 Transtage  

NASA Technical Reports Server (NTRS)

In February 2007 dedicated observations were made of the orbital space predicted to contain debris from the breakup of the Titan 3C-4 transtage back on February 21, 1992. These observations were carried out on the Michigan Orbital DEbris Survey Telescope (MODEST) in Chile with its 1.3deg field of view. The search region or orbital space (inclination and right ascension of the ascending node (RAAN) was predicted using NASA#s LEGEND (LEO-to-GEO Environment Debris) code to generate a Titan debris cloud. Breakup fragments are created based on the NASA Standard Breakup Model (including fragment size, area-to-mass (A/M), and delta-V distributions). Once fragments are created, they are propagated forward in time with a subroutine GEOPROP. Perturbations included in GEOPROP are those due to solar/lunar gravity, radiation pressure, and major geopotential terms. Barker, et. al, (AMOS Conference Proceedings, 2006, pp. 596-604) used similar LEGEND predictions to correlate survey observations made by MODEST (February 2002) and found several possible night-to-night correlations in the limited survey dataset. One conc lusion of the survey search was to dedicate a MODEST run to observing a GEO region predicted to contain debris fragments and actual Titan debris objects (SSN 25000, 25001 and 30000). Such a dedicated run was undertaken with MODEST between February 17 and 23, 2007 (UT dates). MODEST#s limiting magnitude of 18.0 (S\\N approx.10) corresponds to a size of 22cm assuming a diffuse Lambertian albedo of 0.2. However, based on observed break-up data, we expect most debris fragments to be smaller than 22cm which implies a need to increase the effective sensitivity of MODEST for smaller objects. MODEST#s limiting size can be lowered by increasing the exposure time (20 instead of 5 seconds) and applying special image processing. The special processing combines individual CCD images to detect faint objects that are invisible on a single CCD image. Sub-images are cropped from six consecutive CCD images with pixel shifts between images being consistent with the predicted movement of a Titan object. A median image of all the sub-images is then created leaving only those objects with the proper Titan motion. Limiting the median image in this manner brings the needed computer time to process all images taken on one night down to about 50 hours of CPU time.

Barker, E. S.; Matney, M. J.; Yanagisawa, T.; Liou, J.-C.; Abercromby, K. J.; Rodriquez, H. M.; Horstman, M. F.; Seitzer, P.

2007-01-01

400

Recirculating Beam Breakup Study for the 12 GeV Upgrade at Jefferson Lab  

SciTech Connect

Two new high gradient C100 cryomodules with a total of 16 new cavities were installed at the end of the CEBAF south linac during the 2011 summer shutdown as part of the 12-GeV upgrade project at Jefferson Lab. We surveyed the higher order modes (HOMs) of these cavities in the Jefferson Lab cryomodule test facility and CEBAF tunnel. We then studied recirculating beam breakup (BBU) in November 2011 to evaluate CEBAF low energy performance, measure transport optics, and evaluate BBU thresholds due to these HOMs. This paper discusses the experiment setup, cavity measurements, machine setup, optics measurements, and lower bounds on BBU thresholds by new cryomodules.

Ilkyoung Shin, Todd Satogata, Shahid Ahmed, Slawomir Bogacz, Mircea Stirbet, Haipeng Wang, Yan Wang, Byung Yunn, Ryan Bodenstein

2012-07-01

401

Chirally sensitive electron-induced molecular breakup and the Vester-Ulbricht hypothesis.  

PubMed

We have studied dissociative electron attachment in sub-eV collisions between longitudinally polarized electrons and chiral bromocamphor molecules. For a given target enantiomer, the dissociative Br anion production depends on the helicity of the incident electrons, with an asymmetry that depends on the electron energy and is of order 3×10^{-4}. The existence of chiral sensitivity in a well-defined molecular breakup reaction demonstrates the viability of the Vester-Ulbrict hypothesis, namely, that the longitudinal polarization of cosmic beta radiation was responsible for the origins of biological homochirality. PMID:25260009

Dreiling, J M; Gay, T J

2014-09-12

402

SOCIT4 collisional-breakup test data analysis: With shape and materials characterization  

NASA Astrophysics Data System (ADS)

In this paper we revisit the 1995 Kaman database of the SOCIT4 fragment characteristics with added analysis of a subset of the cataloged fragments from the test. This database was compiled from the last of a series of four hypervelocity impact tests conducted under a U.S. Department of Defense program in 1991 1992. This test targeted a flight-ready, U.S. Transit navigation satellite, yielding collision fragments in the size regime of sub-millimeter through tens of centimeters. Results in this database were used in the 1998 NASA Standard Breakup Model to represent characteristic length (size) and area-to-mass distributions of fragments smaller than 10 cm. In this analysis we explore, in detail, the tabulated fragment material and shape. What emerges is a clear distinction in fragment area-to-mass ratio between primarily metal and primarily non-metal fragments. Metal fragments, which are dominated by aluminum, follow the characteristic curve of increasing area-to-mass ratio with decreasing characteristic length: objects move from the character of large irregular bent shards to that of small solid spheroids. Non-metal fragments, dominated by phenolic/plastic, do not appear to move towards solid spheroids as easily as metals. Also unlike the metals, their area-to-mass ratio curve plateaus in the midsize region (smaller than 1 cm), coinciding with a peak in plate-like, non-metal fragments. The internal structure of the Transit payload, with its phenolic surface skin and packed arrays of plastic circuit boards, certainly governs this plateau behavior. In the small fragment regime (smaller than 4 mm) phenolic/plastic ellipsoidal ‘Nuggets’ dominate the population. They outnumber aluminum ‘Nuggets’ by over four to one. Through this study we gain a more detailed understanding of the collisional-breakup process of this particular payload, but also have begun to determine how these data may apply to other breakups. Our long-term goal is to apply this new understanding to future upgrades of the NASA Standard Breakup Model.

Krisko, P. H.; Horstman, M.; Fudge, M. L.

403

Deuteron beam interaction with Li jet for a neutron source test facility  

SciTech Connect

Testing and evaluating candidate fusion reactor materials in a high-flux, high-energy neutron environment are critical to the success and economic feasibility of a fusion device. The current understanding of materials behavior in fission-like environments and existing fusion facilities is insufficient to ensure the necessary performance of future fusion reactor components. An accelerator-based deuterium-lithium system to generate the required high neutron flux for material testing is considered to be the most promising approach in the near future. In this system, a high-energy (30-40 MeV) deuteron beam impinges on a high-speed (10-20 m/s) lithium jet to produce the high-energy (>14 MeV) neutrons required to simulate a fusion environment via the Li (d,n) nuclear stripping reaction. Interaction of the high-energy deuteron beam and the subsequent response of the high-speed lithium jet are evaluated in detail. Deposition of the deuteron beam, jet-thermal hydraulic response, lithium-surface vaporization rate, and dynamic stability of the jet are modeled. It is found that lower beam kinetic energies produce higher surface temperature and consequently higher Li vaporization rates. Larger beam sizes significantly reduce both bulk and surface temperatures. Thermal expansion and dynamic velocities (normal to jet direction) due to beam energy deposition and momentum transfer are much lower than jet flow velocity and decrease substantially at lower beam current densities.

Hassanein, A.

1995-09-01

404

Measurement of the Electric and Magnetic Elastic Structure Functions of the Deuteron at Large Momentum Transfers  

SciTech Connect

The deuteron elastic structure functions, A(Q{sup 2}) and B(Q{sup 2}), have been extracted from cross section measurements of elastic electron-deuteron scattering in coincidence using the Continuous Electron Beam Accelerator and Hall A Facilities of Jefferson Laboratory. Incident electrons were scattered off a high-power cryogenic deuterium target. Scattered electrons and recoil deuterons were detected in the two High Resolution Spectrometers of Hall A. A(Q{sup 2}) was extracted from forward angle cross section measurements in the squared four-momentum transfer range 0.684 ? Q{sup 2} ? 5.90 (GeV/c){sup 2}. B(Q{sup 2}) was determined by means of a Rosenbluth separation in the range 0.684 ? Q{sup 2} ? 1.325 (GeV/c){sup 2}. The data are compared to theoretical models based on the impulse approximation with the inclusion of meson-exchange currents and to predictions of quark dimensional scaling and perturbative quantum chromodynamics. The results are expected to provide insights into the transition from meson-nucleon to quark-gluon descriptions of the nuclear two-body system.

Riad Suleiman

1999-10-01

405

Covariant Spectator Theory of np scattering: Deuteron magnetic moment and form factors  

SciTech Connect

The deuteron magnetic moment is calculated using two model wave functions obtained from 2007 high precision fits to $np$ scattering data. Included in the calculation are a new class of isoscalar $np$ interaction currents which are automatically generated by the nuclear force model used in these fits. After normalizing the wave functions, nearly identical predictions are obtained: model WJC-1, with larger relativistic P-state components, gives 0.863(2), while model WJC-2 with very small $P$-state components gives 0.864(2) These are about 1\\% larger than the measured value of the moment, 0.857 n.m., giving a new prediction for the size of the $\\rho\\pi\\gamma$ exchange, and other purely transverse interaction currents that are largely unconstrained by the nuclear dynamics. The physical significance of these results is discussed, and general formulae for the deuteron form factors, expressed in terms of deuteron wave functions and a new class of interaction current wave functions, are given.

Gross, Franz L. [JLAB

2014-06-01

406

Measurement of the deuteron elastic structure functions at large momentum transfers  

SciTech Connect

The cross section for elastic electron-deuteron scattering has been measured using the Hall A Facility of Jefferson Laboratory. Scattered electrons and recoiling deuterons were detected in coincidence in the two 4 GeV/c High Resolution Spectrometers (HRS) of Hall A. The deuteron elastic structure functions A(Q{sup 2}) and B(Q{sup 2}) have been extracted from these data. Results for the measurement of A(Q{sup 2}) in the range of 0.7 ? Q{sup 2} ? 6.0 (GeV/c){sup 2} are reported. Results for the magnetic structure function, B(Q{sup 2}), are presented in the range of 0.7 ? Q{sup 2} ? 1.35 (GeV/c){sup 2}. The results for both structure functions are compared to predictions of meson-nucleon based models, both with and without the inclusion of meson-exchange currents. The A(Q{sup 2}) results are compared to predictions of the dimensional scaling quark model and perturbative quantum chromodynamics. The results can provide insights into the transition from meson-nucleon to quark-gluon descriptions of the nuclear two-body system.

Kathy McCormick

1999-08-01

407

Three Nucleon Force Effects in Intermediate Energy Deuteron Analyzing Powers for dp Elastic Scattering  

E-print Network

A complete high precision set of deuteron analyzing powers for elastic deuteron-proton ($dp$) scattering at 250 MeV/nucleon (MeV/N) has been measured. The new data are presented together with data from previous measurements at 70, 100, 135 and 200 MeV/N. They are compared with the results of three-nucleon (3N) Faddeev calculations based on modern nucleon-nucleon (NN) potentials alone or combined with two models of three nucleon forces (3NFs): the Tucson-Melbourne 99 (TM99) and Urbana IX. At 250 MeV/N large discrepancies between pure NN models and data, which are not resolved by including 3NFs, were found at c.m.\\ backward angles of $\\theta_{\\rm c.m.}\\gtrsim 120^\\circ$ for almost all the deuteron analyzing powers. These discrepancies are quite similar to those found for the cross section at the same energy. We found small relativistic effects that cannot resolve the discrepancies with the data indicating that other, short-ranged 3NFs are required to obtain a proper description of the data.

K. Sekiguchi; H. Okamura; N. Sakamoto; H. Suzuki; M. Dozono; Y. Maeda; T. Saito; S. Sakaguchi; H. Sakai; M. Sasano; Y. Shimizu; T. Wakasa; K. Yako; H. Wita?a; W. Glöckle; J. Golak; H. Kamada; A. Nogga

2011-06-01

408

Evaluated activation cross sections of longer-lived radionuclides produced by deuteron induced reactions on natural iron up to 10 MeV  

NASA Astrophysics Data System (ADS)

Charged particle induced reactions can be used to monitor in real time the wear of mechanical structures such as internal combustion engines and turbines. Charged particle induced reactions with suitable properties also can be used for monitoring the actual parameters of bombarding particle beams. One of these reactions is the natFe(d,x) 57Co process. The available experimental data in the literature are well established around and above the maximum of the excitation function, however only a little, scattered data are available in the threshold energy region of the reaction. In this work we measured the excitation functions of relevant processes resulting in 55,56,57,58Co, 59Fe and 52,54Mn induced by deuteron beams on natural iron in the energy range from threshold up to 10 MeV. The new experimental data collected are used to determine with high confidence recommended values for the missing low energy part of the investigated excitation functions.

Király, B.; Takács, S.; Ditrói, F.; Tárkányi, F.; Hermanne, A.

2009-01-01

409

New interpretation of proton and deuteron tunneling in 2?-methylacetophenone  

NASA Astrophysics Data System (ADS)

The enol-keto transition rate constants in 2?-methylacetophenone observed by Grellmann et al. [3] are calculated from first principles. The results reinterpret the proposed mechanism and show that proton tunneling is preceded by dissociation of a substrate-solvent complex rather than by rotamer interconversion.

Fernández-Ramos, Antonio; Siebrand, Willem; Smedarchina, Zorka

2013-10-01

410

NPR : Dinosaur-Killing Asteroid Traced to Breakup ... http://www.npr.org/templates/story/story.php?stor... 1 of 2 18/09/2007 12:22  

E-print Network

NPR : Dinosaur-Killing Asteroid Traced to Breakup ... http estimated to be 60 kilometers in diameter. Space Dinosaur-Killing Asteroid Traced to Breakup Event. This was the asteroid that wiped out the dinosaurs and gave mammals a chance. At least that's what a team of planetary

Claeys, Philippe

411

Triassic alkaline magmatism of the Hawasina Nappes: Post-breakup melting of the Oman lithospheric mantle modified by the Permian Neotethyan Plume  

E-print Network

Triassic alkaline magmatism of the Hawasina Nappes: Post-breakup melting of the Oman lithospheric Keywords: Neotethys Passive margin Post-breakup magmatism Triassic Hawasina Oman Mountains Middle to Late Triassic lavas were sampled within three tectonostratigraphic groups of the Hawasina Nappes in the Oman

Demouchy, Sylvie

412

Large-scale climate c-ntr-ls -f Interi-r Alaska river ice breakup1 Peter A. Bieniek1*  

E-print Network

ice can alsice jams and flice stLarge-scale climate c-ntr-ls -f Interi-r Alaska river ice breakup1 2 Peter A. Bieniek1* , Uma S: April 8, 201018 19 20 21 22 23 24 25 26 27 Keywice breakup, Alaska climate

Bhatt, Uma

413

Deformation and breakup of stretching bridges of Newtonian and shear-thinning liquids: comparison of one- and two-dimensional models  

Microsoft Academic Search

Deformation and breakup of bridges of Newtonian and non-Newtonian fluids held captive between two disks that are separated from one another at a constant speed are studied computationally. When the liquid bridge is at the incipience of breakup, a thin liquid thread connects two large volumes of fluid that are pendant from and sessile on the top and bottom disks.

Ozgur E. Yildirim; Osman A. Basaran

2001-01-01

414

Hydroclimatic controls on the occurrence of break-up and ice-jam flooding in the Mackenzie Delta, NWT, Canada  

NASA Astrophysics Data System (ADS)

SummaryConcern has been expressed regarding the impacts of climate change on freshwater aquatic ecosystems in arctic regions. Populated with lakes controlled by flooding from spring break-up ice jams, arctic deltas such as the Mackenzie Delta in northern Canada are particularly sensitive to changing ice break-up conditions and the hydroclimatic controls on break-up and ice-jam flooding. An understanding of these controls is necessary for assessing future climate change effects. This paper presents an assessment of hydroclimatic conditions controlling break-up over the period 1974-2006, with a focus on extreme flood events. Both the upstream driving force, capturing elements of the spring discharge hydrograph, and the downstream resistance force, describing the competence of the downstream ice cover, were quantified with reference to the Mackenzie River at Arctic Red River hydrometric station such that the contribution of each to the severity and timing of break-up could be explored. Results show that the severity of peak break-up stage is most influenced by upstream discharge and the balance between upstream and downstream melt, while timing is related to delta ice conditions and the rise of the spring hydrograph. The highest peak stage events require a rapid rise in discharge and high peak discharge. Minimal downstream melting degree-days and greater ice thickness are also important, although no relationship of these appears to control the level of backwater produced from broken ice and ice jamming effects. The pattern of rapid (protracted) upstream melt and lower (higher) intensity melt in the delta characterizes the highest (lowest) break-up events. For the most severe events, upstream forces are important in controlling discharge-driven events, while an altered hydrologic response occurring for ice-driven events was noted, meriting future examination. Finally, trends toward a longer prebreak-up melt interval, lower peak discharge, rate of rise in discharge, and ice thickness, and higher freeze-up stage were observed, with greater variability of these controls and break-up severity in the most recent decade.

Goulding, Holly L.; Prowse, Terry D.; Bonsal, Barrie

2009-12-01

415

Analysis of exponent values in Gaussian-type functions for development of protonic and deuteronic basis functions  

NASA Astrophysics Data System (ADS)

We analyzed the exponent (?) values in Gaussian-type functions (GTF) for protons and deuterons in BH3, CH4, NH3, H2O, HF, and their deuterated molecules for the development of nuclear basis functions, which are used for molecular orbital (MO) calculations that directly include nuclear quantum effects. The optimized ? (?opt) value in the single s-type ([1s]) GTF for protons is changed due to the difference in flexibility of the electronic basis sets. The difference between the energy obtained by using the ?opt value for each molecule and that obtained by using the average ? (?ave) value for these exponents with the 6-31G(d,p) electronic basis function is only 2 × 10-5 a.u. The ?ave values of protonic and deuteronic [1s] GTFs by the present calculation are 24.1825 and 35.6214, respectively. We found that the ?ave values enable the evaluation of the total energy and the geometrical changes in hydrogen bonding, such as O?H bond O, O?H bond N, and O?H bond C, while the ?opt value became small by forming a hydrogen bond. The result using only the [1s] GTF for the protonic and deuteronic basis functions is sufficient to explain the differences of energy and geometry induced by the H/D isotope effect, although the total energy of ?5 × 10-4 a.u. was improved by using the s-, p-, and d-type ([1s1p1d]) GTFs for protons and deuterons. We clearly demonstrate that the protonic and deuteronic basis functions based on the ?ave value enable us to apply the method to other sample molecules (glycine, malonaldehyde, and formic acid dimer). The protonic and deuteronic basis functions we developed treat the quantum effects of protons and deuterons effectively and extend the application range of the MO calculation to include nuclear quantum effects.

Ishimoto, Takayoshi; Tachikawa, Masanori; Nagashima, Umpei

416

Vibration and Nonlinear Resonance in the Break-up of an Underwater Bubble  

E-print Network

We use high-speed X-ray phase-contrast imaging, weakly nonlinear analysis and boundary integral simulations to characterize the final stage of underwater bubble break-up. The X-ray imaging study shows that an initial azimuthal perturbation to the shape of the bubble neck gives rise to oscillations that increasingly distort the cross-section shape. These oscillations terminate in a pinch-off where the bubble surface develops concave regions that contact similar to what occurs when two liquid drops coalesce. We also present a weakly nonlinear analysis that shows that this coalescence-like mode of pinch-off occurs when the initial shape oscillation interferes constructively with the higher harmonics it generates and thus reinforce each other's effects in bringing about bubble break-up. Finally we present numerical results that confirm the weakly nonlinear analysis scenario as well as provide insight into observed shape reversals. They demonstrate that when the oscillations interfere destructively, a qualitativel...

Lai, Lipeng; Fezzaa, Kamel; Zhang, Wendy W; Nagel, Sidney R

2013-01-01

417

Estimation of debris dispersion due to a space vehicle breakup during reentry  

NASA Astrophysics Data System (ADS)

This paper studies the problem of the estimation of the extent of the airspace containing falling debris due to a space vehicle breakup. A precise propagation of debris to the ground is not practical for many reasons. There is insufficient knowledge of the initial state vector, ambient wind conditions, and the key parameters including the ballistic coefficients. In addition, propagation of all debris pieces to the ground would require extensive computer time. In this paper, a covariance propagation method is introduced for the estimation of debris dispersion due to a space vehicle breakup. The falling debris is simulated, and the data are analyzed to derive the probability of debris evolution in different altitude layers over time. The concept of positional probability ellipsoids is employed for the visualization of the results. Through a case study, it is shown that while the results of the covariance propagation method are in close agreement with those of the Monte Carlo method, the covariance propagation method is much more computationally efficient than the Monte Carlo method.

Reyhanoglu, Mahmut; Alvarado, Juan

2013-05-01

418

JHU/APL Breakup Analysis Tool (APLbat) for the New Horizons Radiological Contingency  

NASA Astrophysics Data System (ADS)

The New Horizons spacecraft will be the first to study Pluto and its largest moon Charon. It launched on 19 January 2006 and will encounter Pluto in 2015. The long duration of the flight, the great distance from the Sun, and the low temperatures in the Pluto-Kuiper Belt necessitate the use of a Radioisotope Thermoelectric Generator (RTG) for heating and electricity. RTGs provide heat and electricity through the radioactive decay of plutonium dioxide (PuO2) fuel pellets. The pellets are contained in protective shells called the General Purpose Heat Source (GPHS) modules. As the New Horizons Pluto-Kuiper Belt mission-implementing organization. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) was responsible for determining the Earth impact footprint of the GPHS modules in the event of an orbital or suborbital re-entry accident during launch. The JHU/APL-developed computer program, APL Breakup Analysis Tool (APLbat), takes estimates of uncertainty in the initial vehicle (spacecraft) position and motion and, using a design-of-experiments approach and a six-degree-of-freedom dynamics model, simulates the continued motion of the vehicle, predicts its breakup as it re-enters the atmosphere, and produces a most probable elliptical Earth impact footprint for the GPHS modules.

Lear, Matthew; McGrath, Brian; Takashima, Naruhisa; Heyler, Gene

2007-01-01

419

Deformation and break-up of viscoelastic droplets in confined shear flow  

E-print Network

The deformation and break-up of Newtonian/viscoelastic droplets are studied in confined shear flow. Our numerical approach is based on a combination of Lattice-Boltzmann models (LBM) and finite difference schemes, the former used to model two immiscible fluids with variable viscous ratio, and the latter used to model the polymer dynamics. The kinetics of the polymers is introduced using constitutive equations for viscoelastic fluids with finitely extensible non-linear elastic dumbbells with Peterlin's closure (FENE-P). We quantify the droplet response by changing the polymer relaxation time $\\tau_P$, the maximum extensibility $L$ of the polymers, and the degree of confinement, i.e. the ratio of the droplet diameter to gap spacing. In unconfined shear flow, the effects of droplet viscoelasticity on the critical Capillary number $\\mbox{Ca}_{\\mbox{\\tiny{cr}}}$ for break-up are moderate in all cases studied. However, in confined conditions a different behaviour is observed: the critical Capillary number of a viscoelastic droplet increases or decreases, depending on the maximum elongation of the polymers, the latter affecting the extensional viscosity of the polymeric solution. Force balance is monitored in the numerical simulations to validate the physical picture.

A. Gupta; M. Sbragaglia

2014-06-16

420

Simulations of the breakup of liquid filaments on a partially wetting solid substrate  

NASA Astrophysics Data System (ADS)

We report direct numerical simulations of liquid filaments breaking up into droplets on partially wetting substrates. It is motivated by recent experiments, linear stability analyses, and lubrication-based calculations. The fluid flow is governed by the Stokes equations and the contact line motion is handled by a phase-field model, which also serves to capture the interfacial motion. The coupled Stokes and Cahn-Hilliard equations are solved using a finite-element algorithm in three dimensions. This avoids additional approximations of the fluid flow or contact line motion, and allows us to compute arbitrary contact angles on the substrate. We simulate both the breakup of infinite liquid filaments via growing capillary waves and that of finite liquid filaments with drops pinching off from the ends, with a focus on the effect of the wetting angle. In both cases, substrate hydrophobicity promotes breakup of the thread, and decreases the spacing of the daughter drops. The results show the differences in the two processes and in the final drop size and spacing. The development of capillary waves agrees well with prior linear analysis and the end-pinching results offer new insights into this poorly understood phenomenon.

Ghigliotti, Giovanni; Zhou, Chunfeng; Feng, James J.

2013-07-01

421

Inviscid Breakup of Bubbles and Drops With and Without Surface Charge  

NASA Astrophysics Data System (ADS)

We present boundary-integral simulations of the breakup of inviscid bubbles and droplets, with and without surface charge. In our simulations, an inner fluid volume of density ?1 is surrounded by an exterior fluid of infinite extent and density ?2. When there is no charge on the surface, we see excellent agreement with previous work, except for intermediate density ratios, where the simulations are plagued by oscillatory instabilities not observed in experiments [1]. With the addition of surface charge, initially spherical drops and bubbles are unstable to small perturbations above a critical surface charge density. For the droplet limit, the charged drop forms a "lemon" shape before ejecting a highly charged jet from the tips of the "lemon," where the size of the jet scales with the square of the inverse surface conductivity. For the bubble limit, we find that fission always takes place by the formation of a "peanut"-shaped bubble, where breakup takes place at the center of the bubble, regardless of surface conductivity. For intermediate densities, combinations of droplet and bubble fission are observed.[4pt] [1] J.C. Burton and P. Taborek, Phys. Rev. Lett. 101, 214502 (2008)

Burton, Justin; Taborek, Peter

2010-11-01

422

Nanometer Contact Physics of Water Ice in Protoplanetary Disks, Breakup, Twisting and Rolling  

NASA Astrophysics Data System (ADS)

The formation of planetary bodies is not yet fully understood. Beyond the snow line in protplanetary disks, volatile components like water condense to solid state. The interaction between these solid particles can cause the formation of larger objects due to aggregation at low velocities, or sometimes -depending on the conditions- their own destruction [1,2] . Water ice has been detected in protoplanetary disks [3,4] and in order to understand its role in the formation of icy bodies like icy planets, asteroids and comets, we carried out laboratory experiments. Water ice aggregates have been formed from frozen liquid water droplets at ~ 190 K. Droplets are smaller than 20 ?m in radius and show a well defined size distribution. At pressure between 0.1 - 1 mbar and temperatures about 200 K, several effects like sublimation, twisting, rolling and breakup have been observed and measured. By the quantification of parameters like mass, acceleration after breakup and aggregate size and structure, the adhesion force that exist in the contact area between the aggregates' monomers, and other parameters, can be determined

Aumatell, Guillem; Wurm, Gerhard

2013-07-01

423

Cryogenic and Simulated Fuel Jet Breakup in Argon, Helium and Nitrogen Gas Flows  

NASA Technical Reports Server (NTRS)

Two-phase flow atomization of liquid nitrogen jets was experimentally investigated. They were co-axially injected into high-velocity gas flows of helium, nitrogen and argon, respectively, and atomized internally inside a two-fluid fuel nozzle. Cryogenic sprays with relatively high specific surface areas were produced, i.e., ratios of surface area to volume were fairly high. This was indicated by values of reciprocal Sauter mean diameters, RSMD's, as measured with a scattered- light scanning instrument developed at NASA Lewis Research Center. Correlating expressions were derived for the three atomizing gases over a gas temperature range of 111 to 422 K. Also, the correlation was extended to include waterjet breakup data that had been previously obtained in simulating fuel jet breakup in sonic velocity gas flow. The final correlating expression included a new dimensionless molecular-scale acceleration group. It was needed to correlate RSMD data, for LN2 and H2O sprays, with the fluid properties of the liquid jets and atomizing gases used in this investigation.

Ingebo, Robert D.

1995-01-01

424

The Characteristics and Consequences of the Break-up of the Fengyun-1C Spacecraft  

NASA Technical Reports Server (NTRS)

The intentional break-up of the Fengyun-1C spacecraft on 11 January 2007 via hypervelocity collision with a ballistic object created the most severe artificial debris cloud in Earth orbit since the beginning of space exploration. More than 900 debris on the order of 10 cm or greater in size have been identified by the U.S. Space Surveillance Network (SSN). The majority of these debris reside in long-lived orbits. The NASA Orbital Debris Program Office has conducted a thorough examination of the nature of the Fengyun-1C debris cloud, using SSN data for larger debris and special Haystack radar observations for smaller debris. These data have been compared with the NASA standard satellite break-up model for collisions, and the results are presented in this paper. The orbital longevity of the debris have also been evaluated for both small and large debris. The consequent long-term spatial density effects on the low Earth orbit (LEO) regime are then described. Finally, collision probabilities between the Fengyun-1C debris cloud and the resident space object population of 1 January 2007 have been calculated. The potential effect on the growth of the near-Earth satellite population is presented.

Johnson, Nicholas L.; Stansbery, Eugene; Liou, Jer-chyi; Horstman, Matt; Stokeley, Christopher; Whitlock, David

2007-01-01

425

Breakup and finite-range effects on the 8B(d,n ) 9C reaction  

NASA Astrophysics Data System (ADS)

The astrophysical factor of 8B(p,? ) 9C at zero energy, S18(0 ) , is determined by a three-body coupled-channels analysis of the transfer reaction 8B(d,n ) 9C at 14.4 MeV/nucleon. Effects of the breakup channels of d and 9C are investigated with the continuum-discretized coupled-channels method. It is found that, in the initial and final channels, respectively, the transfer process through the breakup states of d and 9C , its interference with that through their ground states in particular, gives a large increase in the transfer cross section. The finite-range effects with respect to the proton-neutron relative coordinate are found to be about 20%. As a result of the present analysis, S18(0 ) =22 ±6 eV b is obtained, which is smaller than the result of the previous distorted-wave Born approximation analysis by about 51%.

Fukui, Tokuro; Ogata, Kazuyuki; Yahiro, Masanobu

2015-01-01

426

Semi-Inclusive Charged-Pion Electroproduction off Protons and Deuterons: Cross Sections, Ratios and Access to the Quark-Parton Model at Low Energies  

SciTech Connect

A large set of cross sections for semi-inclusive electroproduction of charged pions (?±) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2 > 4 GeV2 and range in four-momentum transfer squared 2 < Q2 < 4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, Pt2 < 0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W', is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark ? pion production mechanisms. The x, z and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for ?+ and ?-) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.

Asaturyan, R; Mkrtchyan, H; Navasardyan, T; Tadevosyan, V; Adams, G S; Ahmidouch, A; Angelescu, T; Arrington, J; Asaturyan, A; Baker, O K; Benmouna, N; Bertoncini, C; Blok, H P; Boeglin, W U; Bosted, P E; Breuer, H; Christy, M E; Connell, S H; Cui, Y; Dalton, M M; Danagoulian, S; Day, D; Dunne, J A; Dutta, D; El Khayari, N; Fenker, H C; Frolov, V V; Gan, L; Gaskell, D; Hafidi, K; Hinton, W; Holt, R J; Horn, T; Huber, G M; Hungerford, E; Jiang, X; Jones, M; Joo, K; Kalantarians, N; Kelly, J J; Keppel, C E; Kubarovsky, V; Li, Y; Liang, Y; Mack, D; Malace, S P; Markowitz, P; McGrath, E; McKee, P; Meekins, D G; Mkrtchyan, A; Moziak, B; Niculescu, G; Niculescu, I; Opper, A K; Ostapenko, T; Reimer, P E; Reinhold, J; Roche, J; Rock, S E; Schulte, E; Segbefia, E; Smith, C; Smith, G R; Stoler, P; Tang, L; Ungaro, M; Uzzle, A; Vidakovic, S; Villano, A; Vulcan, W F; Wang, M; Warren, G; Wesselmann, F R; Wojtsekhowski, B; Wood, S A; Xu, C; Yuan, L

2012-01-11

427

Applications of optical holography to applied mechanics.  

NASA Technical Reports Server (NTRS)

This paper provides a brief summary of applications of optical holography and holographic interferometry to applied solid mechanics. Basic equations commonly used in fringe interpretation are described and used to reduce the data contained on holographic interferograms. A comparison of data obtained holographically with analytical prediction is given wherever possible. Applications contained herein include front surface physics, study of bomb breakup, transverse wave propagation, study of mode shapes of panels at elevated temperatures, nondestructive testing, and vibration analysis.

Aprahamian, R.

1972-01-01

428

Excitation of states of medium-mass nuclei in the region of giant resonances in inelastic deuteron scattering  

NASA Astrophysics Data System (ADS)

Results are presented that were obtained by measuring a continuum in the inelastic scattering of 37-MeV deuterons on 12C, 48Ti, and 58,64Ni nuclei in the angular range 16° ? ? ? 61°. Broad excitation maxima are found for deuteron scattering angles in the range ? ? 21°. The region of a broad maximum includes giant resonances of target nuclei, whose levels are excited quite readily at E d = 37 MeV. Summation of the inelastic-scattering cross sections over all final states of the excited| nucleus and the use of completeness of the wave functions for these states make it possible to express the total cross section for inelastic (incoherent) deuteron scattering only in terms of the wave functions for the ground state of the target nucleus. The corresponding quasielastic-scattering amplitude is taken in the diffraction approximation. Nucleon correlations in the target nucleus are disregarded. Upon disregarding a small contribution of multiple quasielastic scattering at small scattering angles, the cross section for incoherent deuteron scattering is represented approximately as the product of known factors—the square of the absolute value of the amplitude for diffractive quasielastic scattering and the effective number of target nucleons scattering deuterons. The results of these calculations agree qualitatively with experimental data.

Grantsev, V. I.; Davydovskyy, V. V.; Kisurin, K. K.; Omelchuk, S. E.; Palkin, G. P.; Roznyuk, Yu. S.; Rudenko, B. A.; Saltykov, L. S.; Semenov, V. S.; Slusarenko, L. I.; Struzhko, B. G.; Tartakovsky, V. K.; Shytiuk, V. A.

2008-10-01

429

THE GALACTIC CENTER S-STARS AND THE HYPERVELOCITY STARS IN THE GALACTIC HALO: TWO FACES OF THE TIDAL BREAKUP OF STELLAR BINARIES BY THE CENTRAL MASSIVE BLACK HOLE?  

SciTech Connect

In this paper, we investigate the link between the hypervelocity stars (HVSs) discovered in the Galactic halo and the Galactic center (GC) S-stars, under the hypothesis that they are both the products of the tidal breakup of the same population of stellar binaries by the central massive black hole (MBH). By adopting several hypothetical models for binaries to be injected into the vicinity of the MBH and doing numerical simulations, we realize the tidal breakup processes of the binaries and their follow-up dynamical evolution. We find that many statistical properties of the detected HVSs and GC S-stars could be reproduced under some binary injecting models, and their number ratio can be reproduced if the stellar initial mass function is top-heavy (e.g., with slope {approx} - 1.6). The total number of the captured companions is {approx}50 that have masses in the range {approx}3-7 M{sub Sun} and semimajor axes {approx}< 4000 AU and survive to the present within their main-sequence lifetime. The innermost one is expected to have a semimajor axis {approx}300-1500 AU and a pericenter distance {approx}10-200 AU, with a significant probability of being closer to the MBH than S2. Future detection of such a close star would offer an important test to general relativity. The majority of the surviving ejected companions of the GC S-stars are expected to be located at Galactocentric distances {approx}< 20 kpc, and have heliocentric radial velocities {approx} - 500-1500 km s{sup -1} and proper motions up to {approx}5-20 mas yr{sup -1}. Future detection of these HVSs may provide evidence for the tidal breakup formation mechanism of the GC S-stars.

Zhang Fupeng; Lu Youjun [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Yu Qingjuan [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

2013-05-10

430

Breakup and reestablishment of the armour layer in a large gravel-bed river below dams: The lower Ebro  

Microsoft Academic Search

Changes in armour layer during floods under supply limited conditions are little known. This paper describes the breakup and the reestablishment of the bed armour layer in the regulated gravel-bed Ebro River during a flooding period. The study was conducted over a 28-km study reach from 2002 to 2004. The surface, subsurface and bed load grain size distribution constitute the

Damia Vericat; Ramon J. Batalla; Celso Garcia

2006-01-01

431

ELSEVIER Earth and Planetary Science Letters 160 (1998) 845862 Post-breakup basaltic magmatism along the East Greenland Tertiary  

E-print Network

rights reserved. Keywords: basalts; igneous activity; continental drift; East Greenland; continental emplaced 5­9 My after continental breakup at 55 Ma [1]. Rare earth element (REE) concentrations determined proximity of the mantle plume to the East Greenland continental margin. The low degree of melting at high

432

ELSEVIER Earth-Science Reviews 40 (1996) 229-258 Continental break-up and collision in the Neoproterozoic and  

E-print Network

ELSEVIER Earth-Science Reviews 40 (1996) 229-258 Continental break-up and collision geodynamic models which limited the speeds at which large continental plates could move to an arbitrarily low value. Baltica and Laurentia probably shared a common drift history for the time interval 750-600 Ma

Torsvik, Trond Helge

433

Breakup phenomena of a coaxial jet in the non-dilute region using real-time X-ray radiography  

NASA Astrophysics Data System (ADS)

An innovative approach to the investigation of liquid jet breakup processes in the near-injector region has been developed to overcome the experimental difficulties associated with optically opaque, dense sprays. Real-time X-ray radiography (RTR) has been employed to observe the inner structure and breakup phenomena of coaxial jets. In the atomizing regime, droplets much smaller than the exit diameter are formed beginning essentially at the injector exit. Through the use of RTR, the instantaneous contour of the liquid core was visualized. Experimental results consist of controlled-exposure digital video images of the liquid jet breakup process. Time-averaged video images have also been recorded for comparison. A digital image processing system is used to analyze the recorded images by creating radiance level distributions of the jet. A rudimentary method for deducing intact-liquid-core length has been suggested. The technique of real-time X-ray radiography has been shown to be a viable approach to the study of the breakup processes of high-speed liquid jets.

Cheung, F. B.; Kuo, K. K.; Woodward, R. D.; Garner, K. N.

1990-07-01

434

Astrophysically Important Reaction Rates For Novae And X-ray Bursts From Proton Breakup At Intermediate Energies  

Microsoft Academic Search

We discuss the use of one-nucleon removal reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. The breakup reactions are proved to be good spectroscopic tools and can be used to study a large number of loosely bound proton- or neutron-rich nuclei over a wide range of beam energies. As peripheral processes, they can

A. Banu; L. Trache; F. Carstoiu; N. A. Orr; N. L. Achouri; A. Bonaccorso; W. N. Catford; M. Chartier; B. Fernandez-Dominguez; M. Freer; L. Gaudefroy; M. Horoi; M. Labiche; B. Laurent; R. C. Lemmon; F. Negoita; S. Paschalis; N. Patterson; B. Pietras; B. Roeder; F. Rotaru; P. Roussel-Chomaz; E. Simmons; J. S. Thomas; R. E. Tribble

2010-01-01

435

Connections between the Spring Breakup of the Southern1 Hemisphere Polar Vortex, Stationary Waves, and Air-Sea2  

E-print Network

Connections between the Spring Breakup of the Southern1 Hemisphere Polar Vortex, Stationary Waves, and Air-Sea2 Roughness3 Chaim I. Garfinkel Department of Earth and Planetary Science, Johns Hopkins Earth Observing System Chemistry-Climate11 Model (GEOSCCM). Specifically, an updated air-sea roughness

Garfinkel, Chaim I.

436

Breakup magmatism style on the North Atlantic Igneous Province: insight from Mid-Norwegian volcanic margin  

NASA Astrophysics Data System (ADS)

The distribution of breakup-related igneous rocks on rifted margins provide important constraints on the magmatic processes during continental extension and lithosphere separation which lead to a better understanding of the melt supply from the upper mantle and the relationship between tectonic setting and volcanism. The results can lead to a better understanding of the processes forming volcanic margins and thermal evolution of associated prospective basins. We present a revised mapping of the breakup-related igneous rocks in the NE Atlantic area, which are mainly based on the Mid-Norwegian (case example) margin. We divided the breakup related igneous rocks into (1) extrusive complexes, (2) shallow intrusive complexes (sills/dykes) and (3) deep intrusive complexes (Lower Crustal Body: LCB). The extrusive complex has been mapped using the seismic volcanostratigraphic method. Several distinct volcanic seismic facies units have been identified. The top basalt reflection is easily identified because of the high impedance contrast between the sedimentary and volcanic rocks resulting in a major reflector. The basal sequence boundary is frequently difficult to identify but it lies usually over the intruded sedimentary basin. Then the base is usually picked above the shallow sill intrusions identified on seismic profile. The mapping of the top and the base of the basaltic sequences allows us to determine the basalt thickness and estimate the volume of the magma production on the Mid- Norwegian margin. The thicker part of the basalt corresponds to the seaward dipping reflector (SDR). The magma feeder system, mainly formed by dyke and sill intrusions, represents the shallow intrusive complex. Deeper interconnected high-velocity sills are also mappable in the margin. Interconnected sill complexes can define continuous magma network >10 km in vertical ascent. The large-scale sill complexes, in addition to dyke swarm intrusions, represent a mode of vertical long-range magma transport through the upper crust. The deep intrusive complex represents the Lower Crustal Body (LCB) which is observed along the margin and characterized by high P-wave velocity bodies (Vp> 7km/s). On the Vøring margin a strong amplitude dome-shaped reflection (the so-called T-Reflection) has been identified and interpreted as the top LCB. In the sedimentary part of the margin, sill intrusions are the major feeder system and seem to be connected with LCB. In the volcanic part of the margin, dykes represent the main feeder system and lie above the thicker part of the LCB.

Mansour Abdelmalak, Mohamed; Faleide, Jan Inge; Planke, Sverre; Theissen-Krah, Sonja; Zastrozhnov, Dmitrii; Breivik, Asbjørn Johan; Gernigon, Laurent; Myklebust, Reidun

2014-05-01

437

Seafloor spreading and microcontinent formation during Mesozoic breakup between Australia and Greater India  

NASA Astrophysics Data System (ADS)

The Perth Abyssal Plain (PAP) formed at the nexus of rifting and breakup between three major continents within Gondwana - India, Australia and Antarctica. Oceanic crust within the PAP records the history of Mesozoic seafloor spreading as India moved away from Australia. However, despite the clear importance of the seafloor spreading history of the PAP in constraining the relative motions of these continents during the early stages of breakup, little attention has been paid to the PAP, and particularly its western flank largely due to a lack of new data in collected in this region. We present new observations to constrain the evolution of the PAP, collected during voyage ss2011/v06 of the Southern Surveyor in late 2011. The new data comprise magnetic anomaly profile data, swath bathymetry, and dredge samples collected from 7 sites. The most significant dredge results were obtained from the Batavia Knoll (BK) and Gulden Draak Knoll (GDK), two prominent bathymetric features located >1000 km west of the Australian continental margin. Previous tectonic reconstructions typically treat these bathymetric features as igneous plateaus emplaced on older oceanic crust. However, dredges carried out on the western flanks of each of these knolls recovered continental basement rocks, revealing that both knolls are continental fragments. Estimates of the depths to magnetic sources for shiptrack profiles across the knolls provide evidence for variations in sediment thickness within the knolls. We use forward modeling of shiptrack magnetic profiles combined with gravity anomalies derived from satellite altimetry to make first-order estimates of the extent and spatial variation in thickness of the continental crust. New magnetic anomaly profiles provide evidence for previously unidentified M-series anomalies in the western part of the Perth Abyssal Plain, east of the BK and GDK. These observations both support a reconstruction model in which the microcontinents rifted away from Australia as part of greater India during initial breakup at ~130 Ma. Seafloor spreading in the PAP continued during the early part of the Cretaceous Normal Superchron (until approximately 108 Ma assuming a constant spreading rate inferred from the M-series anomalies). A westward jump in the Australia-India plate boundary led to cessation of spreading in the PAP and the rifting of the BK and GDK from Greater India. Satellite-derived gravity anomalies and swath bathymetry profiles provide evidence for ridge propagation events within the PAP ocean crust, occurring during the Cretaceous Normal Superchron. This series of westwards jumps of the India-Australia plate boundary suggests a strong influence of the Kerguelen hotspot, located beneath eastern greater India at this time.

Williams, S.; Whittaker, J.; Müller, R.

2012-12-01

438

Effects of insoluble surfactants on the nonlinear deformation and breakup of stretching liquid bridges  

SciTech Connect

During the emission of single drops and the atomization of a liquid from a nozzle, threads of liquid are stretched and broken. A convenient setup for studying in a controlled manner the dynamics of liquid threads is the so-called liquid bridge, which is created by holding captive a volume of liquid between two solid disks and pulling apart the two disks at a constant velocity. Although the stability of static bridges and the dynamics of stretching bridges of pure liquids have been extensively studied, even a rudimentary understanding of the dynamics of the stretching and breakup of bridges of surfactant-laden liquids is lacking. In this work, the dynamics of a bridge of a Newtonian liquid containing an insoluble surfactant are analyzed by solving numerically a one-dimensional set of equations that results from a slender-jet approximation of the Navier{endash}Stokes system that governs fluid flow and the convection-diffusion equation that governs surfactant transport. The computational technique is based on the method-of-lines, and uses finite elements for discretization in space and finite differences for discretization in time. The computational results reveal that the presence of an insoluble surfactant can drastically alter the physics of bridge deformation and breakup compared to the situation in which the bridge is surfactant free. They also make clear how the distribution of surfactant along the free surface varies with stretching velocity, bridge geometry, and bulk and surface properties of the liquid bridge. Gradients in surfactant concentration along the interface give rise to Marangoni stresses which can either retard or accelerate the breakup of the liquid bridge. For example, a high-viscosity bridge being stretched at a low velocity is stabilized by the presence of a surfactant of low surface diffusivity (high Peclet number) because of the favorable influence of Marangoni stresses on delaying the rupture of the bridge. This effect, however, can be lessened or even negated by increasing the stretching velocity. Large increases in the stretching velocity result in interesting changes in their own right regardless of whether surfactants are present or not. Namely, it is shown that whereas bridges being stretched at low velocities rupture near the bottom disk, those being stretched at high velocities rupture near the top disk. {copyright} {ital 1999 American Institute of Physics.} thinsp

Ambravaneswaran, B.; Basaran, O.A. [School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907-1283 (United States)] [School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907-1283 (United States)

1999-05-01

439

Comparison of mechanism of break up and cycle length in defibrillation success  

NASA Astrophysics Data System (ADS)

Heart fibrillation is an often fatal condition which can be modeled by chaotic electrical activity; spiral waves of electrical activity rotate, break-up, and meander on tissue. As they do, they produce a chaotic distribution of electrical activity, negatively affecting physical contraction (blood pumping). Fenton, et al. studied several mechanisms of this wave breakup, including ``far from tip'' and ``Doppler shift.'' We used Fenton et al.'s mathem