Status of breakup reaction theory
Recent studies on breakup reactions with the continuum-discretized coupled-channels method are reviewed. The topics covered are: four-body breakup processes for 6He induced reaction, dynamical relativistic effects on Coulomb breakup, microscopic description of projectile breakup processes, description of ternary processes (new triple-α reaction rate) and new approach to inclusive breakup processes.
Statistical theory of breakup reactions
We propose an alternative for Coupled-Channels calculations with loosely bound exotic nuclei (CDCC), based on the the Random Matrix Model of the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCCs), able in principle to take into account many pseudo channels. (author)
Statistical Theory of Breakup Reactions
Bertulani, Carlos A; Hussein, Mahir S
2014-01-01
We propose alternatives to coupled-channels calculations with loosely-bound exotic nuclei (CDCC), based on the the random matrix (RMT) and the optical background (OPM) models for the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCC$_S$), able in principle to take into account many pseudo channels.
Breakup fusion theory of nuclear reactions
Continuum spectra of particles emitted in incomplete fusion reactions are one of the major interests in current nuclear reaction studies. Based on an idea of the so-called breakup fusion (BF) reaction, several authors derived closed formulas for the singles cross section of the particles that are emitted. There have been presented, however, two conflicting cross section formulas for the same BF reaction. For convenience, we shall call one of them the IAV (Ichimura, Austern and Vincent) and the other UT (Udagawa and Tamura) cross section formulas. In this work, the formulation of the UT cross section formula (prior-form) is presented, and the post-form version of the IAV cross section formula is evaluted for a few α- and d-induced reactions based on the exact finite range method. It is shown that the values thus calculated are larger by an order of magnitude as compared with the experimental cross sections for the α-induced reactions, while they are comparable with the experimental cross sections for the d-induced reactions. A possible origin of why such a large cross section is resulted in the case of α-induced reactions is also discussed. Polarization of the residual compound nucleus produced in breakup fusion reactions are calculated and compared with experiments. It is shown that the polarization is rather sensitive to the deflection angles of the strongly absortive partial waves and to obtain a good fit with the experimental data a l-dependent potential in the incident channel is needed in order to stress the lower partial waves
Progress in all-order breakup reaction theories
R Chatterjee
2010-07-01
Progress in breakup reaction theories, like the distorted wave Born approximation, the continuum discretized coupled channels method and the dynamical eikonal approximation, is brought into focus. The need to calculate exclusive reaction observables and the utility of benchmark tests as arbitrators of theoretical models are discussed.
Significance Of Deuteron Breakup In A Halo Transfer Reaction
Yilmaz, M; Yilmaz, Mustafa; Gonul, Bulent
2000-01-01
We discuss the quasi-adiabatic approximations to the three-body wavefunction in breakup processes, clarifying the assumptions underlying the model. This suggests alternative approximation schemes. Using different theoretical three-body models, calculated differential cross section angular distributions for the Be-11(p,d) reaction,for which new preliminary data have been reported at 35 MeV, are presented. We show that calculations are sensitive to the inclusion of deuteron breakup and to the breakup model used, particularly if used to deduce absolute spectroscopic information on the 0{+} and 2{+} Be-10 core state parentages. There is also considerable sensitivity to the model used in calculations of the relative cross sections to the two states.
Break-up stage restoration in multifragmentation reactions
Raduta, Ad.R. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay cedex (France)]|[NIPNE, Bucharest-Magurele, POB-MG 6 (Romania); Bonnet, E.; Borderie, B.; Le Neindre, N.; Rivet, M.F. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay cedex (France); Piantelli, S. [Dip. di Fisica e Sezione INFN, Universita di Firenze, I-50019 Sesto Fiorentino, Fi (Italy)
2007-02-15
In the case of Xe+Sn at 32 MeV/nucleon multifragmentation reaction break-up fragments are built-up from the experimentally detected ones using evaluations of light particle evaporation multiplicities which thus settle fragment internal excitation. Freeze-out characteristics are extracted from experimental kinetic energy spectra under the assumption of full decoupling between fragment formation and energy dissipated in different degrees of freedom. Thermal kinetic energy is determined uniquely while for freeze-out volume - collective energy a multiple solution is obtained. Coherence between the solutions of the break-up restoration algorithm and the predictions of a multifragmentation model with identical definition of primary fragments is regarded as a way to select the true value. The broad kinetic energy spectrum of {sup 3}He is consistent with break-up genesis of this isotope. (authors)
Investigations of nuclear projectile break-up reactions
The cross sections for radiative capture of α-particles, deuterons and protons by light nuclei at very low relative energies are of particular importance for the understanding of the nucleosynthesis of chemical elements and for determining the relative elemental abundances in stellar burning processes at various astrophysical sites. As example we quote the reactions α+d → 6Li+γ, α+3He → 7Be+γ, or α+12C → 16O+γ. As an alternative to the direct experimental study of these processes we consider the inverse process, the photodisintegration, by means of the virtual photons provided by a nuclear Coulomb field: Z+a → Z+b+c. The radiative capture process b+c → a+γ is related to the inverse process, the photodisintegration γ+a → b+c by the detailed balance theorem. Except for the extreme case very close to the threshold the phase space favours the photodisintegration cross section as compared to the radiative capture. The Coulomb dissociation cross section proves to be enhanced due to the large virtual photon number, seen by the passing projectile, and the kinematics of the process leads to particular advantages for studies of the interaction of the two break-up fragments at small relative energies Ebc. The conditions of dedicated experimental investigations are discussed and demonstrated by recent experimental and theoretical studies of the break-up of 156 MeV 6Li projectiles. In addition, a brief review about general features of break-up processes of light ions in the field of atomic nuclei is given. (orig.)
No-capture breakup and incomplete fusion reactions induced by stable weakly bound nucleus 9Be
Seyyedi, S. A.
2016-06-01
The reactions including the stable weakly bound nucleus 9Be have been studied using the classical trajectory model accompanied with the experimental breakup function and the Aage-Winther interaction potential (AW95). In these calculations, the no-capture breakup and the incomplete fusion cross-sections as well as their competition at around the Coulomb barrier have been investigated. Our calculations showed that at a given far-Coulomb-barrier energy the incomplete fusion reaction in different distributions of angular momentum and energies can dominate the no-capture breakup reaction. This dominating process is reversed at the near-barrier energies.
Investigation of the intermediate-energy deuteron breakup reaction
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
Diaz-Torres, Alexis
2007-01-01
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).
A dynamical theory of incomplete fusion reactions: The breakup-fusion reaction approach
A dynamical theory of partial fusion reactions is presented, which may fill the gap between direct and compound nuclear reaction theories. With the new theory one can calculate partial fusion taking place in three-body (and many more) channels reached via direct reactions, e.g., breakup and knockout reactions. The authors present first the results for the cross section for such reactions, taking as an example breakup followed by fusion. They then discuss a physical picture which emerges from their theory, namely that the partial fusion reactions, particularly of the massive-transfer type, take place in a so-called deep peripheral region. It is also shown that the deep peripheral character of such processes diminishes as the mass of the fused system decreases, so that the reactions essentially evolve to the usual peripheral character. Finally, comparisons are made of results of numerical calculations with experimental data, taking as an example the /sup 159/Tb(/sup 14/N,α) reaction with E/sub lab/ = 95 MeV
Final state interactions in electron induced trinucleon breakup reactions
This thesis presents an exact analysis of the electromagnetic breakup process of a trinucleon system. The one-photon exchange mechanism is reviewed. The relevant components of the nuclear current are discussed and the off-shell one-body current matrix elements are derived to accommodate the evaluation of the trinucleon nuclear structure functions. The Faddeev equations are introduced. To facilitate the numerical evaluations the unitary pole expansion (UPE) is employed to describe a local S-wave spin-dependent interaction in a series of separable potential terms. The UPE convergence properties for the trinucleon bound state as well as for the N-N and N-d scattering observables are investigated. In view of the electromagnetic two-body and three-body breakup analysis the half off-shell wave functions for 3N→Nd and 3N→3N scattering are calculated. The nuclear structure functions of the electromagnetic two-body breakup structure functions of the electromagnetic two-body breakup processes are derived and exactly calculated. Results are presented and discussed for several kinetamic configurations. The nuclear response functions of the trinucleon breakup processes are calculated for a momentum transfer Q = 400 MeV/c. The results are compared with recent experimental data for the longitudinal and transverse response of both trinucleon systems. The three-body contributions to the response functions result from an essentially fourfold numerical integration of the invariant electromagnetic three-body breakup amplitude. A detailed derivation of this amplitude is presented and the treatment of the subsequent integration is discussed. An extension is formulated to include D-state components in the trinucleon bound state as well as in the disconnected final state components for the two-body breakup process. One kinematic situation is studied with the D-state extension. For the three-body breakup processes only the PWIA response is determined with the D-state component in the
Approximations in fusion and breakup reactions induced by radioactive beams
Cardenas, W.H.Z.; Carlin Filho, N.; Hussein, M.S. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Canto, L.F.; Donangelo, R. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Lubian, J. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica; Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Havana (Cuba); Romanelli, A. [Facultad de Ingenieria, Montevideo (Uruguay). Inst. de Fisica
2000-07-01
Some commonly used approximations for complete fusion and breakup transmission coefficients in collisions of weakly bound projectiles at near barrier energies are assessed. We show that they strongly depend on the adopted classical trajectory and can be significantly improved with proper treatment of the incident and emergent currents in the WKB approximation. (author)
Classical simulations of heavy-ion fusion reactions and weakly-bound projectile breakup reactions
S S Godre
2014-05-01
Heavy-ion collision simulations in various classical models are discussed. Heavy-ion reactions with spherical and deformed nuclei are simulated in a classical rigid-body dynamics (CRBD) model which takes into account the reorientation of the deformed projectile. It is found that the barrier parameters depend not only on the initial orientations of the deformed nucleus, but also on the collision energy and the moment of inertia of the deformed nucleus. Maximum reorientation effect occurs at near- and below-barrier energies for light deformed nuclei. Calculated fusion crosssections for 24Mg + 208Pb reaction are compared with a static-barrier-penetration model (SBPM) calculation to see the effect of reorientation. Heavy-ion reactions are also simulated in a 3-stage classical molecular dynamics (3S-CMD) model in which the rigid-body constraints are relaxed when the two nuclei are close to the barrier thus, taking into account all the rotational and vibrational degrees of freedom in the same calculation. This model is extended to simulate heavy-ion reactions such as 6Li + 209Bi involving the weakly-bound projectile considered as a weakly-bound cluster of deuteron and 4He nuclei, thus, simulating a 3-body system in 3S-CMD model. All the essential features of breakup reactions, such as complete fusion, incomplete fusion, no-capture breakup and scattering are demonstrated.
Moro, Antonio M.; Lei, Jin
2016-05-01
The problem of the calculation of inclusive breakup cross sections in nuclear reactions is reexamined. For that purpose, the theory proposed by Ichimura et al. (Phys Rev C 32:431, 1985) is revisited, both in its prior and post representations. We briefly outline the connection of this theory with that proposed by Udagawa and Tamura (Phys Rev C 24:1348, 1981) and apply both theories to the inclusive breakup of ^6Li on ^{209}Bi at near-barrier energies, comparing also with available data. The relative importance of elastic versus non-elastic breakup, as a function of the incident energy and of the projectile separation energy, is also investigated.
Study of direct and sequential break-up reactions in 6Li+ 112Sn system
The 6Li projectile while moving in the field of a target nucleus can not only dissociate into α+d but it can also first exchange a few nucleon with the target and then break up into two fragments. Identification of all these processes is important to understand the break-up mechanism of 6Li projectile and also to find the origin of the high yield of alpha particle production in such a reaction. In this paper, we present the exclusive measurement of breakup cross sections in 6Li+112Sn reaction exploring the above possibilities. Cross sections for both sequential as well as direct breakup are measured and compared with the theoretical calculations. The measured elastic scattering angular distributions were used as a constraint to the potential parameters that were used in the calculations to explain both elastic scattering and the breakup processes simultaneously
Casal, J.; Rodríguez-Gallardo, M.; Arias, J. M.; Gómez-Camacho, J.
2016-04-01
A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of B (E 1 ) distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to 11Li (9Li+n +n ) and 6He (4He+n +n ) three-body systems for which some data exist.
Casal, J; Arias, J M; Gómez-Camacho, J
2016-01-01
A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly-bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of $B(E1)$ distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to $^{11}$Li ($^{9}$Li+n+n) and $^6$He ($^{4}$He+n+n) three-body systems for which some data exist.
Experimental study of non-capture breakup reactions at the TANDAR Laboratory
Breakup reactions play a distinctive role among the processes that occur in nuclear collisions induced by weakly bound projectiles. The motivation for the study of these reactions recognizes various origins, that range from their usefulness as an indirect tool to determine cross sections of the corresponding inverse capture processes of astrophysical interest, to the questions that arise from their connection to other reaction channels such as complete and incomplete fusion. For the investigation of these and other aspects it is desirable to have a detailed experimental knowledge of the process and of the underlying mechanisms. In this talk we will review the details and main results of the experiments that are being carried on at the TANDAR Laboratory for the investigation of non-capture breakup reactions, i.e., those for which the breakup products manage to escape from being subsequently absorbed by the target-like nucleus. The measurements involve the coincident detection of the emitted light particles, from which one can obtain an unambiguous and complete characterization of the reaction by means of the identification of the fragment that undergoes breakup (either the projectile or a projectile-like transfer product) and the determination of the total Q value, relative energy of the breakup products, and the angular distribution of their emission in the relevant rest frame. We will describe the tools that are used for the discrimination of resonant processes from those presumably originated in the direct population of the continuum and the conditions for their application. The absolute differential and total cross sections of breakup reactions that have been obtained for 6Li + 144Sm will be presented and discussed, taking as a reference for comparison the corresponding cross sections of competing channels in the same system
Numerical assessment of post-prior equivalence for inclusive breakup reactions
Lei, Jin
2015-01-01
We address the problem of the post-prior equivalence in inclusive breakup reactions induced by weakly-bound nuclei. The problem is studied within the DWBA model of Ichimura, Austern, Vincent [Phys. Rev. C32, 431 (1985)]. The post and prior formulas obtained in this model are briefly recalled, and applied to several breakup reactions induced by deuterons and $^6$Li projectiles, to test their actual numerical equivalence. The different contributions of the prior-form formula are also discussed. A critical comparison with the prior-form distorted-wave Born approximation (DWBA) model of Udagawa and Tamura [Phys. Rev. C24, 1348 (1981)] is also provided.
Reaction mechanism for the symmetric breakup of 24Mg following an interaction with 12C
Data on the yield of the symmetric breakup of 24Mg as a function of beam energy are presented and compared with detailed calculations of the energy dependence. The 24Mg states seen in symmetric breakup agree with previously observed breakup states having spin and parities Jπ=4+,(6+),8+. The data allow the variations of yield for indivual states to be judged, as the beam energy is varied. The variation in the yield of the 4+ states is compared in detail with calculations assuming several possible compound nuclear or direct reaction mechanisms. It is concluded that a massive (12C) transfer or a simple statistical compound process are unlikely mechanisms, but that each of several other mechanisms is consistent with the data. ((orig.))
Vector and tensor analysing powers in deuteron-proton breakup reactions at intermediate energies
Chiladze, D; Dymov, S; Glagolev, V; Hartmann, M; Hejny, V; Kacharava, A K; Keshelashvili, I; Khoukaz, A; Koch, H R; Komarov, V; Kulessa, P; Kulikov, A; Macharashvili, G; Maeda, Y; Mersmann, T; Merzliakov, S; Mikirtytchiants, S; Mussgiller, A; Nioradze, M; Ohm, H; Rathmann, F; Schleichert, R; Stein, H J; Ströher, H; Uzikov, Y; Wilkin, C; Yaschenko, S; Uzikov, Yu.
2006-01-01
Vector and tensor analysing powers of the d(pol)p->(pp)n (charge-exchange) and d(pol)p->(pn)p (non-charge-exchange) breakup reactions have been measured with the ANKE spectrometer at the COSY ring at a deuteron beam energy of 1170 MeV for small momentum transfers to the low excitation energy (pp) or (pn) systems. A quantitative understanding of the values of A_xx and A_yy for the charge-exchange reaction is provided by impulse approximation calculations. The data suggest that spin-flip isospin-flip transitions, which dominate the charge-exchange breakup of the deuteron, are also important in the non-charge-exchange reaction.
Interplay of projectile breakup and target excitation in reactions induced by weakly-bound nuclei
Gomez-Ramos, M
2016-01-01
In this work, we reexamine the extension of the CDCC formalism to include target excitation and apply it to a variety of reactions to study the effect of breakup on inelastic cross sections. We use a transformed oscillator basis to discretize the continuum of the projectiles in the different reactions and use the extended CDCC method developed in this work to solve the resulting coupled differential equations. A new code has been developed to perform the calculations. Reactions 58Ni(d, d) 58Ni*, 24Mg(d, d) 24Mg* , 144Sm( 6Li, 6Li) 144Sm* and 9Be( 6Li, 6Li) 9Be* are studied. Satisfactory agreement is found between experimental data and extended CDCC calculations. The studied CDCC method is proved to be an accurate tool to describe target excitation in reactions with weakly-bound nuclei. Moderate effects of breakup on inelastic observables are found for the reactions studied. Cross section magnitudes are not modified much, but angular distributions present smoothing when opposed to calculations without breakup.
Coulomb dissociation and momentum distributions for 11Li → 9Li + n + n breakup reactions
Momentum distributions for the 11Li → 9Li+n+n breakup reaction, generated by Coulomb dipole excitations, axe calculated in a 3-body model for 11Li. The relative momentum distribution of the two neutrons is in good agreement with recent 3-body coincidence measurements but the momentum distribution for the 9Li recoil and the decay energy spectrum are much narrower than observed. These discrepancies may be due to higher order dynamical effects which have been ignored
Kumari, Anju; Kharab, Rajesh, E-mail: kharabrajesh@rediffmail.com
2015-09-15
The influence of projectile breakup on fusion cross section for {sup 6}He + {sup 209}Bi, {sup 6}He + {sup 64}Zn, {sup 6}Li + {sup 209}Bi and {sup 6}Li + {sup 64}Zn reactions at near barrier energies is studied within the framework of quantum diffusion approach. The breakup does not affect the fusion induced by {sup 6}He, whereas a significant suppression for {sup 6}Li induced reaction is observed in below barrier energy region.
Analysis of Coulomb breakup reactions of 19C on heavy targets
The Coulomb breakup reactions 181Ta(19C, 18C+n)181Ta and 208Pb(19C, 18C+n)208Pb has been investigated at 88 A MeV and 67 A MeV beam energies respectively within the theoretical framework of eikonal approximation with a motive to estimate the relative contribution of higher order multipole transitions, especially of electric quadrupole and dipole-quadrupole interference terms. The results so obtained reflect the finite contribution of electric quadrupole terms at higher relative energies while the dipole-quadrupole interference terms show their presence through longitudinal momentum distribution of core. (author)
Effect of the breakup process on the direct reaction with a 6Li projectile
We investigate the effect of the breakup process on the direct reaction (DR) for 6Li. In order to study this effect, we introduce the experimental and semiexperimental ratio factors Rexpt and Rth by using the semiexperimental and experimental α-production cross sections and DR cross sections. The average values of the ratio Rexpt (Rth) for the 6Li+208Pb and 6Li+209Bi systems are 0.90 (0.91) and 0.86 (0.85), respectively. From these results, it can be seen that the α-production cross sections are the main contribution to the DR cross sections.
The two-proton halo nucleus 17Ne studied in high-energy nuclear breakup reactions
We report on exclusive measurements of nuclear breakup reactions of highly-energetic (500 MeV) unstable 17Ne beams impinging on light targets in an experiment at the R3B-LAND complete-kinematics reaction setup at GSI. Focusing on the properties of beam-like 15O-p (=16F) systems produced in one-proton-removal reactions, we are presenting a comprehensive analysis of the s-/d-wave configuration mixing of the 17Ne valence-proton pair that is used to quantify its halo-nature. The results include the 15O-p relative-energy spectrum, 16F momentum distributions, and their corresponding momentum profile.
Cook, K. J.; Simpson, E. C.; Luong, D. H.; Kalkal, Sunil; Dasgupta, M.; Hinde, D. J.
2016-06-01
Background: Complete fusion cross sections in collisions of light weakly bound nuclei and high-Z targets show suppression of complete fusion at above-barrier energies. This has been interpreted as resulting from the breakup of the weakly bound nucleus prior to reaching the fusion barrier, reducing the probability of complete charge capture. Below-barrier studies of reactions of 9Be have found that the breakup of 8Be formed by neutron stripping dominates over direct breakup and that transfer-triggered breakup may account for the observed suppression of complete fusion. Purpose: This paper investigates how the above conclusions are affected by lifetimes of the resonant states that are populated prior to breakup. If the mean life of a populated resonance (above the breakup threshold) is much longer than the fusion time scale, then its breakup (decay) cannot suppress complete fusion. For short-lived resonances, the situation is more complex. This work explicitly includes the mean life of the short-lived 2+ resonance in 8Be in classical dynamical model calculations to determine its effect on energy and angular correlations of the breakup fragments and on model predictions of suppression of cross sections for complete fusion at above-barrier energies. Method: Previously performed coincidence measurements of breakup fragments produced in reactions of 9Be with 144Sm, 168Er, 186W, 196Pt, 208Pb, and 209Bi at energies below the barrier have been reanalyzed using an improved efficiency determination of the BALiN detector array. Predictions of breakup observables and of complete and incomplete fusion at energies above the fusion barrier are then made using the classical dynamical simulation code platypus, modified to include the effect of lifetimes of resonant states. Results: The agreement of the breakup observables is much improved when lifetime effects are included explicitly. Sensitivity to subzeptosecond lifetime is observed. The predicted suppression of complete fusion
Measurement of the Breakup Cross Sections in 6He+9Be Reaction at 25 MeV/Nucleon
WANG Jia; HU Qing-Yuan; WU Cui-E; A. Ozawa; Y. Yamaguchi; R. Kanungo; D. Fang; I. Tanihata; YE Yan-Lin; JIANG Dong-Xing; ZHANG Gao-Long; PANG Dan-Yang; LI Zhi-Huan; ZHENG Tao; LI Xiang-Qing; WANG Quan-Jin
2005-01-01
@@ The breakup reaction cross sections were measured for the reaction of 6He at 25 MeV/nucleon from 9Be target with intensity of 105 pps. By fitting the energy spectra of breakup α particles with Gaussian functions, the angular distribution of differential cross sections in the laboratory system has been extracted and compared with the Serber model calculations. The good agreement between the calculation and the experimental data favours a dominant configuration of the 4He core plus valence neutrons for the structure of 6He.
Study of the He3 breakup reaction and the triton production spectra at 283 MeV
The breakup of He3 ions at 94MeV/nucleon was studied in inclusive experiments on nuclei ranging from C12 to Pb208, and in coincidence experiments (γd) and (γt) on an A127 target. The inclusive spectra of protons and deuterons show an important contribution of the He3 breakup reaction to the reaction cross section (80%). Analysis of the dependence as a function of A confirms a peripheral mechanism. The coincidence experiment gives a proportion of inelastic breakup in the inclusive cross section of 40 %. Examination of triton spectra reveals that at 94 MeV the dominant reaction is not breakup transfer as at lower energies, but charge exchange. The spectra peak at energies of 20MeV, compatible with the excitation of a mixture of L=1 and L=2 states. The variation of the cross section following an A1/3 law indicates a peripheral mechanism for the (He3,t) reaction too. The (γ-t) coincidence reaction showing residual nucleus production near the target nucleus reinforces this result
Faddeev calculations of break-up reactions with realistic experimental constraints
Kuros-Zolnierczuk, J; Meyer, H O; Whitaker, T J; Witala, H; Golak, J; Kamada, H; Nogga, A; Skibinski, R
2004-01-01
We present a method to integrate predictions from a theoretical model of a reaction with three bodies in the final state over the region of phase space covered by a given experiment. The method takes into account the true experimental acceptance, as well as variations of detector efficiency, and eliminates the need for a Monte-Carlo simulation of the detector setup. The method is applicable to kinematically complete experiments. Examples for the use of this method include several polarization observables in dp break-up at 270 MeV. The calculations are carried out in the Faddeev framework with the CD Bonn nucleon-nucleon interaction, with or without the inclusion of an additional three-nucleon force.
Vector and tensor analyzing powers in deuteron-proton breakup reaction
High precision data for vector and tensor analyzing powers of the 1H( d-vector ,pp)n breakup reaction at 130 and 100 MeV deuteron beam energies have been measured in a large fraction of the phase space. They are compared to the theoretical predictions based on various approaches to describe the three nucleon (3N) system dynamics. Theoretical predictions describe very well the vector analyzing power data, with no need to include any three-nucleon force effects for these observables. Tensor analyzing powers can be also very well reproduced by calculations in most of the studied region, but locally certain discrepancies are observed. At 130 MeV for Axy such discrepancies usually appear, or are enhanced, when model 3N forces are included. Predicted effects of 3NFs are much lower at 100 MeV and at this energy equally good consistency between the data and the calculations is obtained with or without 3NFs.
Experimental study of relativistic effects in the dp breakup reaction using the WASA detector
Kłos B.
2014-03-01
Full Text Available An experiment to investigate the 1H(d→$\\overrightarrow d $, ppn breakup reaction at 340 MeV, 360 MeV and 400 MeV deuteron beam energy has been performed at the Cooler Synchrotron COSY-Jülich with the WASA detector. The main goal was to study of various aspects of few-nucleon dynamics in the medium energy region, with a particular emphasis on relativistic effects and their interplay with three nucelon forces. The almost 4π geometry of the WASA detector gives an unique possibility to study the different aspects of nucleon-nucleon dynamics in the three nucleon system. The preliminary analysis of the collected data is presented.
Cook, K J; Luong, D H; Kalkal, Sunil; Dasgupta, M; Hinde, D J
2016-01-01
Complete fusion cross sections in collisions of light, weakly bound nuclei and high Z targets show above-barrier suppression of complete fusion. This has been interpreted as resulting from breakup of the weakly bound nucleus prior to reaching the fusion barrier, reducing the probability of complete fusion. This paper investigates how these conclusions are affected by lifetimes of the resonant states that are populated prior to breakup. If the mean life of a populated resonance is much longer than the fusion timescale, then its breakup cannot suppress complete fusion. For short-lived resonances, the situation is more complex. This work includes the mean life of the short-lived 2+ resonance in 8Be in classical dynamical model calculations to determine its effect on energy and angular correlations of the breakup fragments and on predictions of fusion suppression. Coincidence measurements of breakup fragments produced in reactions of 9Be with 144Sm, 168Er, 186W, 196Pt, 208Pb and 209Bi at energies below the barrie...
Study of {sup 19}C by breakup reactions; Etude du {sup 19}C par reactions de cassure
Liegard, Emmanuel [Lab. de Physique Corpusculaire, Caen Univ., 14 Caen (France)
1998-01-07
To date studies of halo nuclei have been principally focussed on the A 11 systems {sup 11}Li and {sup 11}Be. The evolution of the properties of the halo with the mass of the system and the binding energy and angular momentum of the halo nucleons is a question of fundamental importance. It was in this spirit that the present study of {sup 19}C (S{sub n} = 240 {+-} 100 keV) was undertaken. The experiment was performed at GANIL using a secondary {sup 19}C beam ({approx_equal} 15 pps at 36 MeV/nucleon) produced via fragmentation. The experimental setup which included the neutron array DEMON, provided for identification of the core-breakup and dissociation reaction channels. In the first case, a very narrow single neutron angular distribution (FWHM = 64 {+-} 17 MeV/c) was observed for {sup 19}C, in contrast to that found for three `reference` nuclei {sup 21}N, {sup 22}O and {sup 24}F (FWHM {approx_equal} 165 MeV/c). This result could be interpreted within the framework of the core-breakup reaction model of a one-neutron halo nucleus. The results obtained for dissociation, while supporting the existence of the halo, indicated that it is not well developed. In addition, a comparison between the present results, the parallel momentum distributions for the core ({sup 18}C) and theoretical predictions have allowed conclusions to be drawn regarding the configuration of the valence neutron. In particular, a purely 2s{sub 1/2} of 1d{sub 5/2} configuration is excluded and mixing, possible with core excited states, must be considered. A probable ground state spin-parity assignment of 3{sup +}/2 or 5{sup +}/2 is suggested. (author) 150 refs., 278 figs., 28 tabs.
The tensor analyzing power T20 in deuteron break-up reactions within the Bethe-Salpeter formalism
The deuteron tensor analyzing power T20 in the deuteron break-up reaction Dp → pX is calculated within a relativistic approach based on the Bethe-Salpeter equation with a realistic meson-exchange potential. Our results on T20 and the cross section are compared with experimental data and non-relativistic calculations and with the outcome of a relativization procedure of the deuteron wave function. (orig.)
GEANT4 simulation of dp non-mesonic breakup reaction at 300 and 500 MeV
GEANT4 simulations of the reaction dp→ppn, i.e. the dp non-mesonic breakup reaction, at 300 and 500 MeV of deuteron energy for different detector configurations are presented. Two threads made from polyethylene and carbon with the thickness of 10 μm are used as targets. The goal of the simulations is to find a method by means of which the signal from the dp non-mesonic breakup can be separated from the background that mainly comes from the carbon content of the CH2 target. The obtained results will be used in the experimental spin program that will be realized at the Nuclotron in Dubna. The aim of this experimental investigation is to contribute to the elucidation of the structure of the spin-dependent parts of the nucleon-nucleon and three-nucleon forces acting in the dp non-mesonic breakup. The deuteron energies will be ranging from 300 up to 500 MeV
A distorted-wave Born-approximation theory of heavy-ion induced projectile break-up reactions
A distorted-wave Born-approximation (DWBA) formalism is developed to describe the 'elastic' and 'inelastic' break-up of the projectile in the heavy ion induced reactions. Using a 'local momentum approximation' and the surface localization property of these reactions expressions for the DWBA transition amplitude are derived. One of the attractive features of the present formulation is the fact that the readial integrals involved in it are the same as those contained in the transition amplitude evaluated with a zero range approximation. The validity of the approximations used in our derivations has been tested and it is shown that these approximations are well fulfilled. (orig.)
Measurement of the reaction 2H(e,e') at 180 degrees close to the deuteron breakup threshold.
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
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
Equivalence of post and prior sum rules for inclusive breakup reactions
A critical examination of sum rules derived previously by Austern and Vincent (post form) and by Udagawa and Tamura (prior form) demonstrates that agreement between the two approaches is obtained if certain approximations implicit in the Udagawa-Tamura prior-form derivation are avoided. We examine the relation of the two approaches to singularities of the post-form distorted wave Born approximation matrix element and to the procedures for reduction of a many-body theory by use of effective operators in a model space. The two-step heuristic model is seen to be invalid for prior-form inelastic breakup; it is necessary to take account of nuclear excitations during projectile breakup. Careful treatment of the non-Hermiticity of kinetic energy operators with respect to continuum wave functions is required
Charge correlations in the breakup of gold projectiles in reactions at E/A=600 MeV
In the present thesis the charge correlations in the breakup of gold projectiles in heavy ion collisions at an incident energy of E/A=600 MeV were studied. Thereby it has been proved that the sum of the charges from the projectile source under exclusion of the protons (Zbound) is saliently suited for the classification of the nuclear reactions. At large values of Zbound we fins fission and spallation reactions. For smaller values of Zbound we observe events with an increasing number of medium-heavy fragments. Thereby the multifragment events appear in the Dalitz diagrams as a continuation of more symmetric becoming spallation events. In reactions with Zbound ≅ 35 the conditions for the formation of medium-heavy fragments are optimal and the multifragment events represent the dominating exit channel. A mean multiplicity of the medium-heavy fragments of ≅ 4 is reached. (orig./HSI)
Investigation of the role of break-up processes on the fusion of 16O induced reactions
An experiment was carried out to explore heavy ion incomplete fusion reaction dynamics, within the framework of the break-up fusion model, at energies near and above the Coulomb barrier. Excitation functions for several radionuclides produced via xn, pxn, and αxn channels were measured in the 16O+181Ta system at energies of ≅76-100 MeV. The experimental excitation functions were compared with those calculated using the theoretical model code PACE4. It was observed that excitation functions of xn/pxn channels are in good agreement with theoretical predictions. However, a significant enhancement in the measured excitation functions of α-emitting channels was observed and attributed to the incomplete fusion processes. The incomplete fusion fraction (FICF) that gives the relative importance of complete and incomplete fusion processes was found to increase with energy. The results are discussed in terms of α-cluster structure of the projectile on various fusion reactions.
Song, Yu-Shou; Hu, Li-Yuan; Liu, Hui-Lan; Wu, Hong-Yi
2015-01-01
The two-body core+$2n$ cluster structure was implemented to describe the two-neutron halo nucleus $^{\\mathrm{14}}\\mathrm{Be}$, where the core$^{\\mathrm{12}}\\mathrm{Be}$ was assumed inert and at ground state and the dineutron was assumed at pure $2S_0$ state. Based on such a structure the three-body continuum-discretized coupled-channel (CDCC) calculation was successfully used to deal with the $^{\\mathrm{14}}\\mathrm{Be}$ breakup reactions of $^{\\mathrm{14}}\\mathrm{Be}+^{\\mathrm{12}}\\mathrm{C}$ at 68~MeV/nucleon and $^{\\mathrm{14}}\\mathrm{Be}+ $Pb at 35~MeV/nucleon.Consequently, we modeled the kinematically complete measurement experiment of $^{\\mathrm{14}}\\mathrm{Be}$ (35~MeV/nucleon) Coulomb breakup at a lead target with the help of Geant4. From the simulation data the relative energy spectrum was constructed by the invariant mass method and $B(E1)$ spectrum was extracted using virtual photon model. The influence of the target thickness and detector performance on the spectroscopy was investigated.
Determination of nn scattering length from data on nn final state interaction in nd-breakup reaction
Full text: An experiment is proposed for the high-precision determination of the neutron-neutron scattering length investigating the nn final state interaction in the nd breakup reaction. The singlet pp and nn scattering lengths are very sensitive probes of the NN-interaction, and their difference is a direct measure of charge-symmetry breaking (CSB) of the nuclear force. However CSB is a small effect, and accurate values of the scattering lengths are needed for a theoretical analysis. The proton-proton scattering length is well known from pp-scattering data (app = -17.3± 0.4 fm), and its uncertainty is mainly due to a model-dependent procedure of removing Coulomb effects. The neutron-neutron scattering length is determined from the following processes n+d→p+n+n, π- + d → γ +n+n, d+d→2He+n+n by investigating the kinematic region of the nn final-state interaction (FSI) where two neutrons fly with low relative energy. The results obtained by now are characterized by a significant uncertainty in values of ann; they are grouped near -16 and -19 fm [1,2], so even the sign of the difference ann - app is uncertain. In this experiment neutron-neutron scattering length is determined by measuring the yield of the nd breakup reaction as a function of the relative energy εnn =(E1 +E2-2(E1E2)1/2cosθ)/2 of two neutrons in the FSI region (two neutrons fly in a narrow angular cone) where nn-interaction is strongly revealed. The theory of reactions in 3N system predicts the εnn dependence of the FSI cross section being sensitive to the value of ann. The measurements will be made using the neutron channel RADEX at Moscow meson factory of the Institute for Nuclear Research. The momenta and angles of the two emitted neutrons and the energy of the proton will be measured for each breakup event. The measured dependence of the reaction yield on the relative energy of the two neutrons will be compared to results of the Monte Carlo simulation that includes the finite geometry
We have studied the single proton breakup from weakly bound exotic nuclei due to several reaction mechanisms separately and their total and the interference effects, in order to clarify quantitatively which mechanism would dominate the measured observables. We have considered: first, the recoil effect of the core-target Coulomb potential which we distinguish from the direct proton-target Coulomb potential, and secondly the nuclear breakup, which consists of stripping and diffraction. Thus, we have calculated the absolute values of breakup cross sections and parallel momentum distributions (LMD) for 8B and 17F projectiles on a light and a heavy target in a range of intermediate incident energies (40 A-80 A MeV) for each reaction mechanism. Furthermore the interference among the two Coulomb effects and nuclear diffraction has been studied in detail. The calculation of the direct and recoil Coulomb effects separately and of their interference is the new and most relevant aspect of this work. (authors)
Analysis of LMD data of core coming from Ta(15C, 14C+n)Ta Coulomb breakup reaction
It is well established fact that the neutron-halo nucleus is a loosely bound exotic nuclear state where in the valence neutron is found mostly at a much larger distance from the remaining core. The development of radioactive ion beams (RI) has provided a great opportunity to explore various peculiar properties of such nuclear systems. Consequently lots of efforts have been made on theoretical and experimental fronts to understand the exotic features of halo nuclei. One of the clear manifestations of exotic properties of isotopes lying near neutron drip line is the loss of magicity and the tendency to posses prolate deformation. In this conference contribution, we study Ta(15C, 14C+n)Ta Coulomb breakup reaction with a special emphasis on the study of effects of deformation and to investigate the possibility of occupying d-orbital by valence neutron in 15 C
Ciepał, I.; Parol, W.; Kalantar-Nayestanaki, N.; Khatri, G.; Kistryn, St.; Kłos, B.; Kozela, A.; Kulessa, P.; Messchendorp, J.; Skwira-Chalot, I.; Stephan, E.; Włoch, B.
2016-03-01
A set of differential cross-section data of the 1H(d, pp)n breakup reaction at 130 and 160 MeV deuteron beam energies has been measured in the forward polar angles domain. The data were collected with the use of the Germanium Wall (FZ Jülich) and BINA (KVI Groningen) detectors. This part of the phase-space is special with respect to the dominant Coulomb force influence on the system dynamics. The data are compared with the theoretical calculations based on the Argonne V18 potential supplemented with the long-range electromagnetic component. The predictions also include the Urbana IX three nucleon force model. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest.
An investigation of the role of spectroscopic factors in the breakup reaction of 11Be
Canbula, Bora; Canbula, Deniz; Babacan, Halil
2014-01-01
The experimental elastic cross section data of the projectile 11Be on target 12C at 49.3 MeV/nucleon energy is analysed. The calculations for the elastic scattering is performed by the phenomenological optical model. The different optical potentials to include breakup effects into the calculations, which are neutron+12C, neutron+10Be and 10Be+12C are described with the aid of the global potentials for neutron interactions and fitted to experimental data for the core and target interaction. Also, the first analysis of the optical model for 10Be on target 12C at 39.1 MeV is done for building the interaction potential of the core and the target for 11Be. For investigating the effects of the spectroscopic factor obtained from the direct capture process using the nuclear level density are compared with the previous cross section and spectroscopic factor results. Obtained results for the elastic cross section are reproduced the experimental data very well, and shows the requirement of including spectroscopic proper...
Mukeru, B.; Lekala, M. L.
2016-08-01
In this paper we analyze the effects of the projectile resonances on the total, Coulomb, and nuclear breakup cross sections as well as on the Coulomb-nuclear interferences at different arbitrary incident energies. It is found that these resonances have non-negligible effects on the total, Coulomb, and nuclear breakup cross sections. Qualitatively, they have no effects on the constructiveness or destructiveness of the Coulomb-nuclear interferences. Quantitatively, we obtained that these resonances increase by 7.38%, 7.58%, and 20.30% the integrated total, Coulomb, and nuclear breakup cross sections, respectively at Elab=35 MeV . This shows that the nuclear breakup cross sections are more affected by the effects of the projectile resonances than their total and Coulomb breakup counterparts. We also obtain that the effects of the resonances on the total, Coulomb, and nuclear breakup cross sections decrease as the incident energy increases.
Wimmer, K; Gade, A; Tostevin, J A; Baugher, T; Chajecki, Z; Coupland, D; Famiano, M A; Ghosh, T K; Grinyer, G F; Hodges, R; Howard, M E; Kilburn, M; Lynch, W G; Manning, B; Meierbachtol, K; Quarterman, P; Ratkiewicz, A; Sanetullaev, A; Stroberg, S R; Tsang, M B; Weisshaar, D; Winkelbauer, J; Youngs, R Winkler M
2012-01-01
The two-proton removal reaction from 28Mg projectiles has been studied at 93 MeV/u at the NSCL. First coincidence measurements of the heavy 26Ne projectile residues, the removed protons and other light charged particles enabled the relative cross sections from each of the three possible elastic and inelastic proton removal mechanisms to be determined. These more final-state-exclusive measurements are key for further interrogation of these reaction mechanisms and use of the reaction channel for quantitative spectroscopy of very neutron-rich nuclei. The relative and absolute yields of the three contributing mechanisms are compared to reaction model expectations - based on the use of eikonal dynamics and sd-shell-model structure amplitudes.
Zemlyanaya, E V; Lukyanov, K V
2010-01-01
The breakup cross sections in the reaction $^6$He+$^{12}$C are calculated at about 40 MeV/nucleon using the high-energy approximation (HEA) and with the help of microscopic optical potentials (OP) of interaction with the target nucleus $^{12}$C of the projectile nucleus fragments $^4$He and 2n. Considering the di-neutron $h$=2n as a single particle the relative motion $h\\alpha$ wave function is estimated so that to explain both the separation energy of $h$ in $^6$He and the rms radius of the latter. The stripping and absorbtion total cross sections are calculated and their sum is compared with the total reaction cross section obtained within a double-folding microscopic OP for the $^6$He+$^{12}$C scattering. It is concluded that the breakup cross sections contribute in about 50% of the total reaction cross section.
Analysis on two-neutron correlation through Dalitz plot of Coulomb breakup reaction for 6He
A new method to describe the three-body decaying states is developed. In this method, the Lippmann–Schwinger equation is combined with the complex scaling method to take the correct boundary condition into account. For the application, the E1 transition strength of 6He is investigated. The energy and Dalitz distributions of the E1 transition are calculated, and the internal correlation of 6He is discussed. As results, it is found that the 6He → 5He(3/2-)+n → 4He+n+n sequential decay process is dominant in the E1 transition reaction of 6He. (author)
Study of the Three-Nucleon Force Effects in the 2H(p, n) Breakup Reaction at 170 MeV
For the study of three nucleon force (3NF) effects in the intermediate energy region, the differential cross sections and the vector analyzing power Ay were measured for the 2H(p, n) inclusive breakup reaction at 170 MeV. The polarized proton beam of 170 MeV was injected to the deuterated polyethylene (CD2) target and the energy of scattered neutrons were deduce by TOF method. The data was compared with the results of the Faddeev calculations with and without 3NFs. Concerning about the differential cross sections, we can see large discrepancies between the data and the calculations in the region where the energies of scattered neutrons are low, which are similar to the results of the 2H(p, p) inclusive breakup reaction at 250 MeV. (author)
Measurement of the 2H(p, n) Breakup Reaction at 170 MeV and the Three-Nucleon Force Effects
The effects of three nucleon force (3NF) have been actively studied via the nucleon–deuteron (Nd) scattering states. The differential cross sections and the vector analyzing powers Ay of the 2H(p, n) inclusive breakup reaction at 170 MeV were measured for the study of 3NF effects in the intermediate energy region. The polarized proton beam of 170 MeV was injected to the deuterated polyethylene (CD2) target and the energy of scattered neutrons were measured by using TOF method. The data were compared with the Faddeev calculations based on modern nucleon–nucleon (NN) forces with and without the 3NF. Concerning the differential cross sections, we can see large discrepancies between the data and the calculations in the region of scattered neutron energies are low, which is similar to the results of the 2H(p, p) inclusive breakup reaction at 250 MeV. (author)
A study of 11 Be an 11 Li halo nuclei by core breakup reactions
The study of light nuclei with large neutron excess are very useful for the understanding of nuclear matter far from stability. The nuclear halo phenomenon has been observed for the first time for Z 11 Be and 11 Li halo nuclei. In this channel, the neutron is supposed not to participate to the reaction and then, when detected, to carry out the same properties as in the halo nucleus. The deduced widths of the neutron momentum distributions are different from the one extracted from the core distributions and with the more recent theoretical models. From these studies, it is also stressed that the properties of the core are essential to understand the halo phenomenon. In particular, the correlation between the core vibrations and the halo neutron are able to explain the emergence of the halo in 11 Be. (author)
What does determine the competition between complete fusion, incomplete fusion and breakup reactions
A series of γ-charged particle coincidence experiments were performed with the aim to identify simulatanously both the target and the projectile residues in heavy-ion induced reactions. The study concentrates on the mechanism of the production of 'fast' α-particles in 12C + 160Gd collisions at four bombarding energies: 90, 120, 160 and 200 MeV. Inclusive α-particle production cross sections increase in this energy range from 570 mb at E(12C) = 90 MeV to 2100 mb at E(12C) = 200 MeV. At forward angles the energy spectra of singles α-particles are bell-shaped with the mean energy close to Esub(α) = 1/3E(12C). Contribution of evaporation α-particles is negligible at forward angles and high bombarding energies. Angular distributions of the 'fast' component are peaked at forward angles, and they fall down with angle almost exponentially. (orig./AH)
Studies of the Three-Nucleon System Dynamics in the Deuteron-Proton Breakup Reaction
Ciepał I.
2014-03-01
$$\\overrightarrow d$ , ppn reaction was investigated experimentally at 100 and 130 MeV deuteron beam energies. Rich set of data for cross section, vector and tensor analyzing powers was obtained with the use of the SALAD and BINA detectors at KVI and Germanium Wall setup at FZ-Jülich. Results are compared with various theoretical approaches which describe the three-nucleon (3N system dynamics. For correct description of the cross section data both, three-nucleon force (3NF and Coulomb force, have to be included into calculations and influence of those ingredients is seizable at specific parts of the phase space. In case of the vector analyzing powers very low sensitivity to any effects beyond nucleon-nucleon interaction was found. At 130 MeV, the Axy data are not correctly described when 3NF models are included into calculations.
Nuclear break-up has been studied both from an experimental and a theoretical point of view and has shown to be a powerful tool to probe nucleon correlations in nuclei. A theory beyond mean-field, called TDDM, (Time Dependant Density Matrix) taking into account two-body correlations has been developed. The dynamical evolution of a correlated nuclei can be described and especially nuclear break-up. This study shows that the distributions of relative angle between the two neutrons strongly differ when varying initial correlations: two nucleons close together in the nuclei will lead to small relative angle after emission whereas two nucleons far from each other gives large relative angles. From an experimental point of view, correlations between the two neutrons in the halo of the Borromean nucleus He6 have been investigated. Its ground state is predicted to have two dominant configurations: the di-neutron configuration where the two neutrons are very close to each other and the cigar configuration, where the two neutrons are on opposite side with respect to the core. Nuclear break-up of He6 on a lead target has been studied at GANIL with a SPIRAL beam. The alpha particles coming out of the break-up where detected by a stripped Silicon detector coupled to a Silicon-Lithium detector and the neutrons by EDEN and the Neutron Wall, in order to get a large angular coverage. Angular correlation functions extracted from data show both strong correlation at small relative angles and at large relative angle corresponding respectively to the contribution of the di-neutron configuration and of the cigar like configuration. So He6 ground state seems to be a superposition of these two configurations. (author)
In the framework of the impulse approximation, the relation between the effective cross section of the charge-exchange breakup of a fast deuteron d + a → (pp) + b and the effective cross section of the charge transfer process n + a → p + b is discussed. In doing so, the effects of the proton identity (Fermi-statistics) and of the Coulomb and strong interactions of protons in the final state are taken into account. The distribution over relative momenta of the protons, produced in the charge-exchange process d + p → (pp) + n in the forward direction, is investigated. At the transfer momenta being close to zero the effective cross section of the charge-exchange breakup of a fast deuteron, colliding with the proton target, is determined only by the spin-flip part of the amplitude of the charge transfer reaction n + p → p + n at the zero angle. It is shown that the study of the process d + p → (pp) + n in a beam of the polarized (aligned) deuterons allows one, in principle, to separate two spin-dependent terms in the amplitude of the charge transfer reaction n + p → p + n, one of which does not conserve and the other one conserves the projection of the nucleon spin onto the direction of momentum at the transition of the neutron into the proton
A method of calculation of the triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup at astrophysically relevant energies E of the relative motion of the breakup fragments, taking into account the three-body (α - d - 208Pb) Coulomb effects and the contributions from the E1- and E2- multipoles, including their interference, has been proposed. The new results for the astrophysical S-factor of the direct radiative capture d(α, γ)6 Li reaction at E ≤ 250 keV have been obtained. It is shown that the experimental triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup can also be used to give information about the value of the modulus squared of the nuclear vertex constant for the virtual 6Li → α + d. (author)
Measurement of the 12C(e,e′p)11B two-body breakup reaction at high missing momentum
The five-fold differential cross section for the 12C(e,e′p)11B reaction was determined over a missing momentum range of 200–400 MeV c−1, in a kinematics regime with xB>1 and Q2=2.0 (GeV c−1)2. A comparison of the results with previous lower missing momentum data and with theoretical models are presented. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV c−1. The theoretical calculations are from two very different approaches, one mean field and the other short range correlated; yet for this system the two approaches show striking agreement with the data and each other up to a missing momentum value of 325 MeV c−1. For larger momenta, the calculations diverge which is likely due to the factorization approximation used in the short range approach. (paper)
Grevy, S. [Institut de Physique Nucleaire, CNRS - IN2P3 Universite Paris Sud, 91406 Orsay Cedex (France)
1997-12-31
The study of light nuclei with large neutron excess are very useful for the understanding of nuclear matter far from stability. The nuclear halo phenomenon has been observed for the first time for Z < 10 nuclei in 80`s: halo nuclei consist of a `stable` core (neutron separation energy of about a few MeV) and one or two neutrons with a very low separation energy of about a few hundred keV. Their wave functions can extent from the core at distances larger than the main range of nuclear force. These halo nuclei have been studied by dissociation reactions in which the neutron from the halo is detected in coincidence with the core. It has been shown that the extraction of the halo wave function is strongly influenced by (i) the reaction mechanism itself (ii) final state interactions. In the present work core breakup reactions are used in which the halo neutron is detected in anticoincidence with the core to study the {sup 11} Be and {sup 11} Li halo nuclei. In this channel, the neutron is supposed not to participate to the reaction and then, when detected, to carry out the same properties as in the halo nucleus. The deduced widths of the neutron momentum distributions are different from the one extracted from the core distributions and with the more recent theoretical models. From these studies, it is also stressed that the properties of the core are essential to understand the halo phenomenon. In particular, the correlation between the core vibrations and the halo neutron are able to explain the emergence of the halo in {sup 11} Be. (author). 78 refs.
Influence of the breakup on the fusion and scattering process
We present results of the study of the influence of the break-up process on the fusion, scattering and reaction cross sections, at near barrier energies. Most of the discussed reactions and scattering mechanisms are induced by the stable weakly bound nuclei 6,7 Li and 9 Be, although comparisons with reactions induced by strongly bound nuclei are also made. We give a picture of the break-up and fusion mechanisms at energies above the Coulomb barrier. (author)
Asymptotic and near-target direct breakup of 6Li and 7Li
Kalkal, Sunil; Simpson, E. C.; Luong, D. H.; Cook, K. J.; Dasgupta, M.; Hinde, D. J.; Carter, I. P.; Jeung, D. Y.; Mohanto, G.; Palshetkar, C. S.; Prasad, E.; Rafferty, D. C.; Simenel, C.; Vo-Phuoc, K.; Williams, E.; Gasques, L. R.; Gomes, P. R. S.; Linares, R.
2016-04-01
Background: Li,76 and 9Be are weakly bound against breakup into their cluster constituents. Breakup location is important for determining the role of breakup in above-barrier complete fusion suppression. Recent works have pointed out that experimental observables can be used to separate near-target and asymptotic breakup. Purpose: Our purpose is to distinguish near-target and asymptotic direct breakup of Li,76 in reactions with nuclei in different mass regions. Method: Charged particle coincidence measurements are carried out with pulsed Li,76 beams on 58Ni and 64Zn targets at sub-barrier energies and compared with previous measurements using 208Pb and 209Bi targets. A detector array providing a large angular coverage is used, along with time-of-flight information to give definitive particle identification of the direct breakup fragments. Results: In interactions of 6Li with 58Ni and 64Zn, direct breakup occurs only asymptotically far away from the target. However, in interactions with 208Pb and 209Bi, near-target breakup occurs in addition to asymptotic breakup. Direct breakup of 7Li into α -t is not observed in interactions with 58Ni and 64Zn. However, near-target dominated direct breakup was observed in measurements with 208Pb and 209Bi. A modified version of the Monte Carlo classical trajectory model code platypus, which explicitly takes into account lifetimes associated with unbound states, is used to simulate sub-barrier breakup reactions. Conclusions: Near-target breakup in interactions with Li,76 is an important mechanism only for the heavy targets 208Pb and 209Bi. There is insignificant near-target direct breakup of 6Li and no direct breakup of 7Li in reactions with 58Ni and 64Zn. Therefore, direct breakup is unlikely to suppress the above-barrier fusion cross section in reactions of Li,76 with 58Ni and 64Zn nuclei.
Breakup branches of Borromean beryllium-9
The breakup reaction 9Be(4He, 3α)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in 9Be up to 12 MeV were populated and reconstructed through the measurement of the charged reaction products. It is proposed that limits on the spins and parities of the states can be derived from the way that they decay. Various breakup paths for excited states in 9Be have been explored including the 8Beg.s. + n, 8Be2+ + n and 5Heg.s. + 4He channels. By imposing the condition that the breakup proceeded via the 8Be ground state, clean excitation spectra for 9Be were reconstructed. The remaining two breakup channels were found to possess strongly-overlapping kinematic signatures and more sophisticated methods (referenced) are required to completely disentangle these other possibilities. Emphasis is placed on the development of the experimental analysis and the usefulness of Monte-Carlo simulations for this purpose
Breakup branches of Borromean beryllium-9
Smith, R., E-mail: r.smith.3@pgr.bham.ac.uk; Freer, M.; Wheldon, C.; Curtis, N.; Ashwood, N. I.; Barr, M.; Kokalova, Tz.; Malcolm, J. D.; Ziman, V. A. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Almaraz-Calderon, S.; Aprahamian, A.; Bucher, B.; Couder, M.; Fang, X.; Jung, F.; Lu, W.; Roberts, A.; Tan, W. P. [Institute for Structure and Nuclear Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Copp, P.; Lesher, S. R. [Department of Physics, University of Wisconsin - La Crosse, La Crosse, WI 54601 (United States); and others
2015-10-15
The breakup reaction {sup 9}Be({sup 4}He, 3α)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in {sup 9}Be up to 12 MeV were populated and reconstructed through the measurement of the charged reaction products. It is proposed that limits on the spins and parities of the states can be derived from the way that they decay. Various breakup paths for excited states in {sup 9}Be have been explored including the {sup 8}Be{sub g.s.} + n, {sup 8}Be{sub 2{sup +}} + n and {sup 5}He{sub g.s.} + {sup 4}He channels. By imposing the condition that the breakup proceeded via the {sup 8}Be ground state, clean excitation spectra for {sup 9}Be were reconstructed. The remaining two breakup channels were found to possess strongly-overlapping kinematic signatures and more sophisticated methods (referenced) are required to completely disentangle these other possibilities. Emphasis is placed on the development of the experimental analysis and the usefulness of Monte-Carlo simulations for this purpose.
Breakup branches of Borromean beryllium-9
Smith, R.; Freer, M.; Wheldon, C.; Curtis, N.; Almaraz-Calderon, S.; Aprahamian, A.; Ashwood, N. I.; Barr, M.; Bucher, B.; Copp, P.; Couder, M.; Fang, X.; Goldring, G.; Jung, F.; Kokalova, Tz.; Lesher, S. R.; Lu, W.; Malcolm, J. D.; Roberts, A.; Tan, W. P.; Ziman, V. A.
2015-10-01
The breakup reaction 9Be(4He, 3α)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in 9Be up to 12 MeV were populated and reconstructed through the measurement of the charged reaction products. It is proposed that limits on the spins and parities of the states can be derived from the way that they decay. Various breakup paths for excited states in 9Be have been explored including the 8Beg.s. + n, 8Be2+ + n and 5Heg.s. + 4He channels. By imposing the condition that the breakup proceeded via the 8Be ground state, clean excitation spectra for 9Be were reconstructed. The remaining two breakup channels were found to possess strongly-overlapping kinematic signatures and more sophisticated methods (referenced) are required to completely disentangle these other possibilities. Emphasis is placed on the development of the experimental analysis and the usefulness of Monte-Carlo simulations for this purpose.
11Li structural information from inclusive break-up measurements
Fernández-García J. P.
2015-01-01
Full Text Available Structure information of 11Li halo nucleus has been obtained from the inclusive break-up measurements of the 11Li+208Pb reactions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV. The effective break-up energy and the slope of B(E1 distribution close to the threshold have been extracted from the experimental data.
Systematic study of breakup effects on complete fusion at energies above the Coulomb barrier
Wang, Bing; Gomes, P R S; Zhao, En-Guang; Zhou, Shan-Gui
2014-01-01
A large number of complete fusion excitation functions of reactions including the breakup channel were measured in recent decades, especially in the last few years. It allows us to investigate the systematic behavior of the breakup effects on the complete fusion cross sections. To this end, we perform a systematic study of the breakup effects on the complete fusion cross sections at energies above the Coulomb barrier. The reduced fusion functions $F(x)$ are compared with the universal fusion functions which are used as a uniform standard reference. The complete fusion cross sections at energies above the Coulomb barrier are suppressed by the breakup of projectiles. This suppression effect for reactions induced by the same projectile is independent of the target and mainly determined by the lowest energy breakup channel of the projectile. There holds a good exponential relation between the suppression factor and the energy corresponding to the lowest breakup threshold.
The weakly bound 9Be and tightly bound 10B, neighbouring projectiles were used on the 116Sn and 115In respectively; both reactions leading to the same compound nucleus 125Xe. The present study was carried out near the barrier varying the beam energy
Medium modifications of the nucleon--deuteron break--up cross section in the Faddeev approach
M. Beyer; G. Röpke; Sedrakian, A.
1996-01-01
The three--nucleon scattering problem in a nuclear medium is considered within the Faddeev technique. In particular the deuteron break--up cross section that governs the formation and the break--up reactions of deuterons (NNN Nd) in a nuclear environment is calculated at finite temperatures and densities. A significant enhancement of the in--medium break--up cross section with increasing density has been found.
Tumino, A.; Spitaleri, C.; Sergi, M.L.; Cherubini, S.; La Cognata, M.; Lamia, L.; Romano, S.; Tudisco, S. [Universita di Catania, Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); Kroha, V.; Burjan, V.; Novac, J.; Vincour, J. [Nuclear Physics Institute of ASCR, Rez, Prague (Czech Republic); Fueloep, Z.; Somorjai, E. [Institute of Nuclear Research of Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Pizzone, R.G. [INFN Laboratori Nazionali del Sud, Catania (Italy)
2006-03-15
The Trojan Horse Method (THM) was applied to the {sup 3}He+{sup 7}Li interaction in order to investigate the quasi-free {sup 7}Li(p,{alpha}){sup 4}He reaction. The three-body experiment was performed at 33 MeV corresponding to a {sup 7}Li-p relative energy ranging from 50 keV to 7 MeV. The extracted {sup 7}Li(p,{alpha}){sup 4}He quasi-free cross-section was compared with the behavior of direct data, as well as with the result of a previous THM investigation on the {sup 7}Li(p,{alpha}){sup 4}He reaction off the neutron in {sup 2}H. A good agreement between data sets shows up throughout the energy range investigated, providing a very important validity test of the pole approximation for the THM. (orig.)
A computer ''experiment'' using Monte Carlo sampling methods has been designed to simulate the breaking up of 12C by medium-energy neutrons into final reaction channels having 2, 3, or 4 outgoing charged particles. The calculational nuclear physics concept used in the ''experiment'' is one of a sequentially decaying, highly excited compound nucleus. Two methods of Monte Carlo sampling, the rejection method and the cumulative-distribution method, are discussed as applied to probability functions developed in the program
Hard breakup of two nucleons from the 3He nucleus
We investigate a large angle photodisintegration of two nucleons from the 3He nucleus within the framework of the hard rescattering model (HRM). In the HRM a quark of one nucleon knocked out by an incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with large relative momentum. Assuming the dominance of the quark-interchange mechanism in a hard nucleon-nucleon scattering, the HRM allows the expression of the amplitude of a two-nucleon breakup reaction through the convolution of photon-quark scattering, NN hard scattering amplitude, and nuclear spectral function, which can be calculated using a nonrelativistic 3He wave function. The photon-quark scattering amplitude can be explicitly calculated in the high energy regime, whereas for NN scattering one uses the fit of the available experimental data. The HRM predicts several specific features for the hard breakup reaction. First, the cross section will approximately scale as s-11. Second, the s11 weighted cross section will have the shape of energy dependence similar to that of s10 weighted NN elastic scattering cross section. Also one predicts an enhancement of the pp breakup relative to the pn breakup cross section as compared to the results from low energy kinematics. Another result is the prediction of different spectator momentum dependencies of pp and pn breakup cross sections. This is due to the fact that the same-helicity pp-component is strongly suppressed in the ground state wave function of 3He. Because of this suppression the HRM predicts significantly different asymmetries for the cross section of polarization transfer NN breakup reactions for circularly polarized photons. For the pp breakup this asymmetry is predicted to be zero while for the pn it is close to (2/3).
Nuclear Interference effects in 8B sub-Coulomb breakup
Nunes, F. M.; Thompson, I.J.
1998-01-01
The breakup of $^8$B on $^{58}$Ni below the Coulomb barrier was measured recently with the aim of determining the Coulomb breakup components. We reexamine this reaction, and perform one step quantum-mechanical calculations that include E1, E2 and nuclear contributions. We show that the nuclear contribution is by no means negligible at the intermediate angular range where data was taken. Our results indicate that, for an accurate description of this reaction, Coulomb E1, E2 and nuclear process...
Measurement of the 12C(e,e'p)11B Two-Body Breakup Reaction at High Missing Momentum Values
Monaghan, P; Shneor, R; Subedi, R; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertin, P; Bertozzi, W; Boeglin, W; Chen, J P; Choi, Seonho; Chudakov, E; Ciofi degli-Atti, C; Cisbani, E; Cosyn, W; Craver, B; de Jager, C W; Feuerbach, R J; Folts, E; Frullani, S; Garibaldi, F; Gayou, O; Gilad, S; Gilman, R; Glamazdin, O; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; Jans, E; Jiang, X; Jiang, Y; Kaufman, L; Kelleher, A; Kolarkar, A; Kuchina, E; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Morita, H; Nanda, S; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Reitz, B; Ron, G; Rosner, G; Ryckebusch, J; Saha, A; Sawatzky, B; Segal, J; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Thompson, N; Ulmer, P E; Urciuoli, G M; Voutier, E; Wang, K; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Yao, H; Zheng, X; Zhu, L
2014-08-01
The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. The theoretical calculations agree well with the data up to a missing momentum value of 325 MeV/c and then diverge for larger missing momenta. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV/c.
Measurement of the 12C(e,e'p)11B Two-Body Breakup Reaction at High Missing Momentum Values
Monaghan, P; Subedi, R; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertin, P; Bertozzi, W; Boeglin, W; Chen, J P; Choi, Seonho; Chudakov, E; Atti, C Ciofi degli; Cisbani, E; Cosyn, W; Craver, B; de Jager, C W; Feuerbach, R J; Folts, E; Frullani, S; Garibaldi, F; Gayou, O; Gilad, S; Gilman, R; Glamazdin, O; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; Jans, E; Jiang, X; Jiang, Y; Kaufman, L; Kelleher, A; Kolarkar, A; Kuchina, E; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Morita, H; Nanda, S; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Reitz, B; Ron, G; Rosner, G; Ryckebusch, J; Saha, A; Sawatzky, B; Segal, J; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Thompson, N; Ulmer, P E; Urciuoli, G M; Voutier, E; Wang, K; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Yao, H; Zheng, X; Zhu, L
2013-01-01
The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. The theoretical calculations agree well with the data up to a missing momentum value of 325 MeV/c and then diverge for larger missing momenta. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV/c.
Breakup mechanisms for 7Li + 197Au, 204Pb systems at sub-barrier energies
Luong D.H.
2013-12-01
Full Text Available Coincidence measurements of breakup fragments were carried out for the 7Li + 197Au and 204Pb systems at sub-barrier energies. The mechanisms triggering breakup, and time-scales of each process, were identified through the reaction Q-values and the relative energy of the breakup fragments. Binary breakup of 7Li were found to be predominantly triggered by nucleon transfer, with p-pickup leading to 8Be → α + α decay being the preferred breakup mode. From the time-scales of each process, the coincidence yields were separated into prompt and delayed components, allowing the identification of breakup process important in the suppression of complete fusion of 7Li at above-barrier energies.
^{11}Li structural information from inclusive break-up measurements
Fernandez-Garcia, J. P.; Cubero, M.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Borge, M. J. G.; Buchmann, L.; Diget, C. A.; Falou, H. A.; Fulton, B. R.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Kanungo, R.; Lay, J. A.; Madurga, M.; Martel, I.; Moro, A. M.; Mukha, I.; Nilsson, T.; Rodriguez-Gallardo, M.; Sanchez-Benitez, A. M.; Shotter, A.; Tengblad, O.; Walden, P.
2015-01-01
Structure information of Li-11 halo nucleus has been obtained from the inclusive break-up measurements of the Li-11+Pb-208 reactions at energies around the Coulomb barrier (E-lab = 24.3 and 29.8 MeV). The effective break-up energy and the slope of B(E1) distribution close to the threshold have be...
Percolation picture of nucleus break-up
The production of nuclear fragments in multifragmentation and spallation reactions is viewed as a percolation phenomenon. A model of nuclear percolation is proposed. The criteria for linkage of nucleons to a cluster are defined in real and momentum spaces. In addition, ''compactness'' conditions are imposed to the clusters in both spaces. This model behaves in many respects as a two-dimensional site percolation model, exhibiting a rather well defined percolation threshold at psub(c) approximately 0.6. The concentration p is related to the number of fast particles leaving the nuclear volume. We discuss possible experimental signatures of this new break-up mechanism
Polarization measurements in pion deuteron breakup and absorption
The reactions which form the pion-NN system are discussed. Rare and sensitive spin transfer observables involving the deuteron spin are reported. The improvements performed in the uncertainty associated with the only observable measured in pion deuteron breakup are presented
Study on breakup mechanism of unstable nuclei with CDCC
Matsumoto, T
2015-01-01
The continuum-discretized coupled-channels method (CDCC) has been successful in describing breakup reactions involving unstable nuclei. Moreover, CDCC is a useful method for evaluation of nuclear data, which are important for nuclear engineering. In this article, we present the theoretical foundation of CDCC and some results of CDCC analyses.
Breakup of molten aluminum drops
To clarify the entrapment of water and the breakup mechanism in molten Al drops, a series of experiments was carried out by pouring molten Al of 10 to 20 g (up to 1,000degC) into a highly subcooled-water pool (room temperature) through the air. A single large-scale water jet, which is capable of penetrating a molten Al drop, was found to appear above the molten Al drop immediately after an air column which the molten drop is dragging from the water surface, is detached. It was observed with a high frequency that a molten Al drop begins swelling first, and is then broken up during falling through the water pool or after hitting the basement. It was also found that the breakup always occurs in the course of solid crust formation, and the molten drop solidified without breakup forms a large cavity inside. Based on the experimental observations, it is concluded that the swelling and the breakup of a molten Al drop should be caused by the water entrapped inside and the hydrogen remaining super-saturated. It is reasonable to consider that an intensive breakup should be caused when some quantity of water is injected into a molten Al drop with a capability that a high-pressure vapor is generated due to a rapid release of latent heat just after brittle cracks occur during swelling. (author)
Deuteron–deuteron scattering above four-nucleon breakup threshold
A. Deltuva
2015-03-01
Full Text Available Deuteron–deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit Δ-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated.
Deuteron-deuteron scattering above four-nucleon breakup threshold
Deltuva, A
2015-01-01
Deuteron-deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit $\\Delta$-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated.
Deuteron–deuteron scattering above four-nucleon breakup threshold
Deltuva, A., E-mail: arnoldas.deltuva@tfai.vu.lt [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Goštauto 12, LT-01108 Vilnius (Lithuania); Fonseca, A.C. [Centro de Física Nuclear da Universidade de Lisboa, P-1649-003 Lisboa (Portugal)
2015-03-06
Deuteron–deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit Δ-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated.
Inclusive breakup of Borromean nuclei
Hussein, Mahir S; Frederico, Tobias
2016-01-01
We derive the inclusive breakup cross section of a three-fragment projectile nuclei, $a = b +x_1 + x_2$, in the spectator model. The resulting four-body cross section for observing $b$, is composed of the elastic breakup cross section which contains information about the correlation between the two participant fragments, and the inclusive non-elastic breakup cross section. This latter cross section is found to be a non-trivial four-body generalization of the Austern formula \\cite{Austern1987}, which is proportional to a matrix element of the form, $\\langle\\hat{\\rho}_{{x_1},{x_2}}\\left|\\left[W_{{x_1}} + W_{{x_2}} + W_{3B}\\right]\\right|\\hat{\\rho}_{{x_1}, {x_2}}\\rangle$. The new feature here is the three-body absorption, represented by the imaginary potential, $W_{3B}$. We analyze this type of absorption and supply ideas of how to calculate its contribution.
Mechanisms of Li-projectile breakup-up
Various experimental and theoretical features observed in recent studies of break-up of 6Li and 7Li projectiles in the field of atomic nuclei are discussed, in particular for the transitional energy regime of 10-30 MeV/amu. The discussion is organized as three independent lectures presented at the International School on Nuclear Physics, Kiev (UkSSR), 28 May - 8 June, 1990. After a survey on the main experimental facts and on the basic reaction mechanisms, current theoretical approaches are illustrated by an application to the analysis of elastic break-up of 156 MeV 6Li projectiles. Finally Coulomb break-up is discussed as a novel tool of laboratory nuclear astrophysics. (orig.)
High Energy Break-Up of Few-Nucleon Systems
Sargsian, Misak
2008-03-01
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.
High Energy Break-Up of Few-Nucleon Systems
Sargsian, Misak M
2008-01-01
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.
Elastic Coulomb breakup of 34Na
Singh, G.; Shubhchintak, Chatterjee, R.
2016-08-01
Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our
Elastic breakup cross sections of well-bound nucleons
Wimmer, K; Gade, A; Tostevin, J A; Baugher, T; Chajecki, Z; Coupland, D; Famiano, M A; Ghosh, T K; Howard, G F Grinyer 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
2014-01-01
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.
Simulation of deuteron break-up at Tp=2.5 GeV for ANKE facility
The experimental conditions for studying the deuteron break-up are simulated on the basis of pd interaction events generated by the ROC model at the energy Tp=2.5 GeV. The background conditions for separation of the break-up reaction pd→ppn at this energy are examined. 13 refs., 8 figs., 2 tabs
Elastic and break-up of the 1n-halo 11Be nucleus
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
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.
Elastic and break-up of the 1n-halo 11Be nucleus
Di Pietro A.
2014-03-01
Full Text Available 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.
Evidence for elastic {sup 16}O breakup into the {alpha}-{sup 12}C continuum
Tatischeff, V.; Auger, P.; Bogaert, G.; Coc, A.; Kiener, J.; Lefebvre, A. [Institut National de Physique Nucleaire et de Physique des Particules (IN2P3), 75 - Paris (France); Disdier, D.; Kraus, L.; Linck, I. [Strasbourg-1 Univ., 67 (France); Mittig, W. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Stephan, C. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; and others
1996-09-01
Radiative capture cross section have been measured by the method of breakup of a {sup 16}O beam at 95 MeV/A, which is particularly sensitive to the E2 part. The elastic breakup of {sup 16}O into {sup 12}C and {alpha} induced by Coulomb interaction with the electric field of a heavy nucleus may be regarded as the time reversed radiative capture reaction. (K.A.). 11 refs.
Breakup of loosely bound nuclei as indirect method in nuclear astrophysics. 8B, 9C, 23Al
We discuss the use of one-nucleon breakup reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. These are peripheral processes, therefore from breakup reaction data we can extract asymptotic normalization coefficients (ANC) from which reaction rates of astrophysical interest can be precisely evaluated. In particular, the breakup of 8B and 9C is described in detail in terms of an extended Glauber model. The results of this new analysis lead to the astrophysical factor S17(0) = 18.7 ± 1.9 eVb for the key reaction for solar neutrino production 7Be(p,γ)8B. We discuss a proposed use of the breakup of proton drip line nucleus 23Al to obtain the stellar reaction rate for 22Mg(p,γ)23Al. (author)
Observation of auroral fading before breakup
We have obtained detailed observations of the onset of auroral breakup using a variety of instruments with time resolution of some tens of seconds. 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. At the time of the fading there is a brief darkening of the poleward sky. Often the breakup is preceded by one or more rapid intensifications, each one preceded by local fading. Pseudo-breakups may also occur without the development of a major event. A bonafide breakup may begin on the fading arc, on an adjacent arc, or in an entirely new region nearby. This optical activity is closely correlated with the development of auroral radar echoes, suggesting that variations in the ionospheric and magnetospheric electric and magnetic fields are responsible for the observed auroral variations. Data from the IMS magnetometer network provide some indication of a correlated response by the local auroral and ionospheric current, although this could be partly due to changes in conductivity. Riometer recordings show a slow decrease in ionsperic 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. The implications of these observations regarding the trigger mechanism for the expansion phase of a magnetospheric substorm are discussed. (author)
Theoretical studies on reaction mechanisms of unstable nuclei
Recent studies on reactions of unstable nuclei by means of the continuum-discretized coupled-channels method (CDCC) are briefly reviewed. The topics covered are: four-body breakup processes for 6He induced reaction, microscopic description of projectile breakup processes, and new approach to inclusive breakup processes. (author)
Microscopic Description of Diffractive Deuteron Breakup by He-3 Nuclei
Kovalchuk, Valery
2016-01-01
A microscopic formalism for describing observed cross sections for deuteron breakup by three-nucleon nuclei was developed on the basis of the diffraction nuclear model. A general formula that describes the amplitude for the reaction d+3He->3He+p+n and which involves only one adjustable parameter was obtained by using expansions of the integrands involved in terms of a Gaussian basis. This formula was used to analyze experimental data on the exclusive cross sections for deuteron breakup by He-3 nuclei at the projectile energy of 89.4 MeV. The importance of employing, in calculations, a deuteron wave function that has a correct asymptotic behavior at large nucleon-nucleon distances was demonstrated.
Investigation of correlations in the breakup of He8
Correlations in light neutron-rich nuclei are of considerable importance in understanding their structure. In this context the breakup of He8 into He6 + 2n has been investigated at 15 MeV/nucleon. The measurements were undertaken using a setup composed of two detector arrays: CHARISSA to detect the charged fragments and DEMON to detect the neutrons. The interpretation of the results was facilitated using a Monte Carlo simulation which was developed to take into account the correlations, the reaction and the experimental setup. Two techniques were used to study the correlations in the breakup of He8. The first, intensity interferometry, provides, via the construction of the neutron-neutron correlation function, for a first estimate of the source size and thus the average separation between the neutrons. The second, using Dalitz plots, allows both the neutron-neutron and core-neutron correlations to be probed. Here, sequential decay via the ground state resonance of He7 and has been found to dominate the dissociation of He8. The spatial and temporal characteristics of the breakup of He8 have thus been deduced and a root-mean-square separation between the two valence neutrons in the continuum states was estimated to be (7.3 ± 0.6) fm with a time delay between their emission of (1000 ± 300) fm/c. (author)
Neutron Induced D Breakup in Inertial Confinement Fusion at the Omega Laser Facility
Forrest, C. J.; Glebov, V. Yu.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.; Schroder, W. U.; Frenje, J. A.; Gatu Johnson, M.
2015-11-01
High-resolution neutron spectroscopy is used to study the deuteron breakup reaction D(n,n ') np in the thermonuclear environment created in inertial confinement fusion experiments at the Omega Laser Facility. Neutrons with an energy of 14.1 MeV generated in the primary D-T fusion reactions scatter elastically and inelastically off the dense (cryogenic) D-T fuel assembly surrounding the central hot spot at peak fuel compression. These neutrons also induce a breakup of the fuel deuterons. The corresponding breakup cross section is measured relative to elastic n -D and n -T scattering, i.e., simultaneously in the same environment. Apart from astrophysical and technological interest, the neutron-induced deuteron breakup reaction is of interest to the physics of nucleon -nucleon forces. For example, theoretical calculations predict a noticeable influence of nucleonic three-body forces on the magnitude of the breakup cross section. Preliminary results from measurements of the neutron contribution in the 2- to 6-MeV range show reasonable agreement with the published ENDL 2008.2 semi-empirical cross-section. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Study of pairing and clusterization in light nuclei through nuclear break-up
Nuclear break-up is a powerful tool to investigate nuclear structure as it is sensitive to the quantum properties of the emitted particles. This reaction mechanism has been used to investigate several aspects of correlations. First, the case of 11Be was studied where the spectroscopic factors for the two configurations where extracted. Secondly, the spectroscopic factor for alpha clusterization in the ground state of 40Ca was measured. Finally the correlation between the two neutrons in the halo of 6He emitted through breakup reactions showed strong contribution for the di-neutron configuration. (authors)
Negative Emotions and Behaviors are Markers of Breakup Distress
Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeanette
2013-01-01
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…
Intrusive Thoughts: A Primary Variable in Breakup Distress
Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette
2013-01-01
University students who were high versus low on breakup distress scores were given self-report measures to assess their intrusive thoughts about the romantic breakup and their somatic symptoms that followed the breakup as well as their extracurricular activities and social support that might alleviate their breakup distress. In a regression…
Fragmentation processes in nuclear reactions
Fragmentation processes in nuclear collisions are reviewed. The main emphasis is put on light ion breakup at nonrelativistic energies. The post- and prior-form DWBA theories are discussed. The post-form DWBA, appropriate for the ''spectator breakup'' describes elastic as well as inelastic breakup modes. This theory can also account for the stripping to unbound states. The theoretical models are compared to typical experimental results to illustrate the various possible mechanisms. It is discussed, how breakup reactions can be used to study high-lying single particle strength in the continuum; how it can yield information about momentum distributions of fragments in the nucleus. (orig.)
Bocage, F; Louvel, M; Auger, G; Bacri, C O; Bellaize, N; Borderie, B; Bougault, R; Brou, R; Buchet, P; Charvet, J L; Chbihi, A; Cussol, D; Dayras, R; De Cesare, N; Demeyer, A N; Doré, D; Durand, D; Frankland, J D; Galíchet, E; Genouin-Duhamel, E; Gerlic, E; Guinet, D; Lautesse, P; Laville, J L; Lecolley, J F; Legrain, R; Le Neindre, N; López, O; Maskay, A M; Nalpas, L; Nguyen, A D; Pârlog, M; Péter, J; Plagnol, E; Rivet, M F; Rosato, E; Saint-Laurent, F; Salou, S; Steckmeyer, J C; Stern, M; Tabacaru, G; Tamain, B; Tirel, O; Tassan-Got, L; Vient, E; Vigilante, M; Volant, C; Wieleczko, J P; Le Brun, C; Genoux-Lubain, A; Rudolf, G; Stuttgé, L
2000-01-01
Recent experimental results concerning heavy systems (Pb + Au, Pb + Ag, Pb + Al, Gd + C, Gd + U, Xe + Sn, etc) obtained at GANIL with the INDRA and NAUTILUS 4 pi arrays will be presented. The study of reaction mechanisms has shown the dominant binary and highly dissipative character of the process. The two heavy and excited fragments produced after the first stage of the interaction can decay into various decay modes from evaporation to multifragmentation including fission. However, deviations from this simple picture have been found by analyzing angular and velocity distributions of light charged particles, and fragments. Indeed, there is a certain amount of matter in excess emitted between the two primary sources suggesting either the existence of a mid-rapidity source similar to the one observed in the relativistic regime (participants) or a strong deformation induced by the dynamics of the collision (neck instability). This last possibility has been suggested by analyzing in detail the angular distributio...
Recent developments in the eikonal description of the breakup of exotic nuclei
Capel, P; Esbensen, H; Fukui, T; Johnson, R C; Nunes, F M; Ogata, K
2015-01-01
The study of exotic nuclear structures, such as halo nuclei, is usually performed through nuclear reactions. An accurate reaction model coupled to a realistic description of the projectile is needed to correctly interpret experimental data. In this contribution, we briefly summarise the assumptions made within the modelling of reactions involving halo nuclei. We describe briefly the Continuum-Discretised Coupled Channel method (CDCC) and the Dynamical Eikonal Approximation (DEA) in particular and present a comparison between them for the breakup of 15C on Pb at 68AMeV. We show the problem faced by the models based on the eikonal approximation at low energy and detail a correction that enables their extension down to lower beam energies. A new reaction observable is also presented. It consists of the ratio between angular distributions for two different processes, such as elastic scattering and breakup. This ratio is completely independent of the reaction mechanism and hence is more sensitive to the projectile...
Theory of inclusive breakup cross section for Borromean nuclei within a four-body spectator model
Carlson, Brett V; Hussein, Mahir S
2016-01-01
We develop a model to treat the inclusive non-elastic break up reactions involving weakly bound three-cluster nuclei. Borromean, two-nucleon, halo nuclei are candidates of unstable three-fragments projectiles. The model is based on the theory of inclusive breakup reactions commonly employed in the treatment of incomplete fusion and surrogate method. The theory was developed in the 80's by Ichimura, Autern and Vincent (IAV) [Phys. Rev. C 32, 431 (1985)] \\cite{IAV1985}, Udagawa and Tamura (UT)[Phys. Rev. C 24, 1348 (1981)], \\cite{UT1981} and Hussein and McVoy (HM)[Nucl. Phys. A 445, 124 (1985)], \\cite{HM1985}. We extend these three-body theories to derive an expression for the fragment yield in the reaction $A\\,(a,b)\\,X$, where the projectile is $a = x_1 + x_2 + b$. The inclusive breakup cross section is found to be the sum of a generalized four-body form of the elastic breakup cross section plus the inclusive non-elastic breakup cross section which involves the "reaction" cross section of the participant fragm...
Influence of the halo upon angular distributions for elastic scattering and breakup
The angular distributions for elastic scattering and breakup of halo nuclei are analysed using a near-side/far-side decomposition within the framework of the dynamical eikonal approximation. This analysis is performed for 11Be impinging on Pb at 69 MeV/nucleon. These distributions exhibit very similar features. In particular they are both near-side dominated, as expected from Coulomb-dominated reactions. The general shape of these distributions is sensitive mostly to the projectile-target interactions, but is also affected by the extension of the halo. This suggests the elastic scattering not to be affected by a loss of flux towards the breakup channel.
Duan, R.-O.; 越塚 誠一; 高田 孝; 山口 彰
2004-01-01
The JNC cooperative research scheme on the nuclear fuel cycle with The University of Tokyo has been carried out to investigate a flow regime and interfacial area density of multi-phase flow in sodium-water reaction using the Moving-Particle Semi-implicit (MPS) method.
Three-body coupled-channel theory of scattering and breakup of light and heavy ions
It is shown that the method of coupled discretized continuum channels (CDCC) based on the three-body model for direct reactions is very successful in explaining the following, recently developed experiments using deuteron, 6Li and 7Li projectiles whose breakup threshold energies are very low: (i) Precise measurement of all the possible analyzing powers in elastic scattering of polarized deuteron at 56 MeV, (ii) scattering of polarized deuteron at intermediate energies, (iii) deuteron projectile breakup at 56 MeV, (iv) scattering of polarized 7Li at 20 and 44 MeV and (v) projectile breakup of 6Li at 178 MeV and 7Li at 70 MeV. The CDCC analyses of those data are made transparently with no adjustable parameters. (author)
Far-field breakup of spiral waves in the plankton ecological systems
Liu, Quan-Xing
2007-01-01
For oscillatory conditions, breakup of the spiral waves far away from the spiral core (as so-called "far-field breakup") was reported in a simple activator-inhibitor model by Markus B\\"{a}r, Michal Or-Guil and Lutz Brusch [Phys. Rev. Lett. \\textbf{82}, 1160 (1999) and New J. Phys. \\textbf{6}, 5 (2004)], which is in the chemical reaction-diffusion system. In present letter, the scenario in the plankton ecological system is reported. The spatial plankton model is studied numerically by computer and we find that the far-field breakup also exists in the oceanic ecological systems over a range of diffusion coefficients of phytoplankton and zooplankton. The far-field breakup leading to the spatial chaos patterns can be verified in field observation and is useful to understand the population dynamics of oceanic ecological systems. It also indicates that the far-field breakup may be a common phenomenon in the world. Finally, we give some illumination from the ecological meaning.
Nuclear-breakup mechanisms in the interaction of relativistic projectiles with heavy targets
The breakup of a Au nucleus under bombardment with relativistic p, α, and 20Ne 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
Critical exponents in nucleus breakup
In recent years the study of cluster formation has become a new field in statistical physics. Nuclear reactions with particle number change can be viewed as a cluster formation processes. Multifragmentation decay produces a power law distribution of medium size clusters. These two cluster size distributions resemble that of many others statistical cluster formation processes. We discuss now these analogies in some details
Elastic Coulomb breakup of $^{34}$Na
Singh, G; Chatterjee, R
2016-01-01
Purpose : The aim of this paper is to study the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb to give us a core of $^{33}$Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of $^{34}$Na. Method : A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb at 100 MeV/u. The triple differential cross-section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum and angular distributions as well as the average momenta, along with the energy-angular distributions. Results : The total one neutron removal cross-section is calculated to test the possible ground state configurations of $^{34}$Na. The average momentum results along with energy-angular calculations indicate $^{34}$Na to ha...
Kočenda, Evžen; Hanousek, Jan
2012-01-01
Roč. 13, č. 2 (2012), s. 121-143. ISSN 1435-6104 R&D Projects: GA ČR GA402/09/1595 Institutional support: PRVOUK-P23 Keywords : break-up of firms * corporate performance * ownership changes Subject RIV: AH - Economics Impact factor: 0.588, year: 2012
Projectile deformation effects in the breakup of $^{37}$Mg
Shubhchintak,; Shyam, R
2015-01-01
We study the breakup of $^{37}$Mg on Pb at 244MeV/u with the recently developed extended theory of Coulomb breakup within the post-form finite range distorted wave Born approximation that includes deformation of the projectile. Comparing our calculated cross section with the available Coulomb breakup data we determine the possible ground state configuration of $^{37}$Mg.
De Fazio, Dario
2014-06-21
In this work, we present a quantum mechanical scattering study of the title reaction from 1 mK to 2000 K. Total integral cross sections and thermal rate constants are compared with previous theoretical and experimental data and with simpler theoretical models to understand the range of validity of the approximations used in the previous studies. The obtained quantum reactive observables have been found to be nearly insensitive to the roto-vibrational energy of the reactants at high temperatures. More sensitive to the reactant's roto-vibrational energy are the data in the cold and ultra-cold regimes. The implications of the new data presented here in the early universe scenario are also discussed and analyzed. PMID:24810283
Entrainment instability and vertical motion as causes of stratocumulus breakup
Weaver, C. J.; Pearson, R., Jr.
1990-01-01
Entrainment instability is thought to be a cause of stratocumulus breakup. At the interface between the cloud and the overlying air, mixtures may form which are negatively buoyant because of cloud droplet evaporation. Quantities devised to predict breakup are obtained from aircraft observations and are tested against cloud observations from satellite. Often, the parameters indicate that breakup should occur but the clouds remain, sometimes for several days. One possible explanation for breakup is vertical motion from passing synoptic cyclones. Several cases suggest that breakup is associated with the downward vertical motion from the cold air advected behind an eastward moving cyclone.
Proton-neutron correlation in the deuteron breakup at 56 MeV and prior-form DWBA analysis
Proton-neutron angular correlations in the 12C, 51V and 118Sn(d,pn) reactions have been measured at 56 MeV to investigate the deuteron breakup process. The elastic breakup which leaves the target nucleus in its ground state dominates the coincident spectra. The experimental data have been analyzed using the prior-form DWBA. For both nuclear and Coulomb breakup, sufficient convergence of the calculations is obtained by including the pn angular momenta up to l=2. For the nuclear breakup calculations, the l=0 and 2 contributions dominate the cross sections. For the Coulomb breakup the l=1 contribution is predominant. The DWBA calculations reproduce the experimental data in the angular region where the protons are emitted on the side of the beam opposite to the neutrons. On the other hand the calculations overestimate the breakup cross sections by a factor of 2 to 10 in the angular region where the protons are emitted on the same side of the beam as the neutrons. The disagreement may be due to the insufficient treatment of the final-state distorted wave in the prior-form DWBA. (author)
Ice breakup: Observations of the acoustic signal
Waddell, S. R.; Farmer, D. M.
1988-03-01
We describe observations of ambient sound beneath landfast ice in the Canadian Arctic Archipelago and interpret its evolution over the period June-August in terms of ice cracking and disintegration. The data were recorded on six bands between 50 and 14,500 Hz for the period April 2 to August 7, 1986, in Dolphin and Union Strait. The frequency dependence of the attenuation of sound in water allows separation of distant and local noise sources. In conjunction with satellite imagery and meteorological data, it is shown that strong signals in the acoustic time series are associated with major breakup events. The acoustic signal can provide predictive information about ice conditions and the approach of breakup.
Lima, V; Lacroix, D; Blumenfeld, Y; Bourgeois, C; Chabot, M; Chomaz, Ph; Désesquelles, P; Duflot, V; Duprat, J; Fallot, M; Frascaria, N; Grévy, S; Guillemaud-Müller, D; Roussel-Chomaz, P; Savajols, H; Sorlin, O
2007-01-01
The break-up of 11Be was studied at 41AMeV using a secondary beam of 11Be from the GANIL facility on a 48Ti target by measuring correlations between the 10Be core, the emitted neutrons and gamma rays. The nuclear break-up leading to the emission of a neutron at large angle in the laboratory frame is identified with the towing mode through its characteristic n-fragment correlation. The experimental spectra are compared with a model where the time dependent Schrodinger equation (TDSE) is solved for the neutron initially in the 11 Be. A good agreement is found between experiment and theory for the shapes of neutron experimental energies and angular distributions. The spectroscopic factor of the 2s orbital is tentatively extracted to be 0.46+-0.15. The neutron emission from the 1p and 1d orbitals is also studied.
Basis for breakup states of three identical particles
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. (author)
Breakup of Bubbles in Turbulent Flow.
Vejražka, Jiří; Stanovský, Petr; Tihon, Jaroslav
Ozarow Mazowiecki : Nobell Compressing sp. z o.o, 2015 - (Kosinsky, K.; Urbanczyk, M.; Žerko, S.), s. 70 ISBN N. [Smart and Green Interfaces Conference - SGIC2015. Belgrade (RS), 30.03.2015-01.04.2015] R&D Projects: GA MŠk(CZ) LD13018 Institutional support: RVO:67985858 Keywords : bubble breakup * turbulent flow * velocity Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Fractal aggregation and breakup of fine particles
Li Bingru
2016-01-01
Full Text Available Breakup may exert a controlling influence on particle size distributions and particles either are fractured or are eroded particle-by-particle through shear. The shear-induced breakage of fine particles in turbulent conditions is investigated using Taylor-expansion moment method. Their equations have been derived in continuous form in terms of the number density function with particle volume. It suitable for future implementation in computational fluid dynamics modeling.
The Beam Break-Up Numerical Simulator
Travish, G.A.
1989-11-01
Beam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution. 50 refs., 18 figs., 5 tabs.
The Beam Break-Up Numerical Simulator
Beam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution. 50 refs., 18 figs., 5 tabs
Droplet Breakup of the Nematic Liquid Crystal MBBA
Nachman, Benjamin
2012-01-01
Droplet breakup is a well studied phenomena in Newtonian fluids. One property of this behavior is that, independent of initial conditions, the minimum radius exhibits power law scaling with the time left to breakup tau. Because they have additional structure and shear dependent viscosity, liquid crystals pose an interesting complication to such studies. Here, we investigate the breakup of a synthetic nematic liquid crystal known as MBBA. We determine the phase of the solution by using a cross polarizer setup in situ with the liquid bridge breakup apparatus. Consistent with previous studies of scaling behavior in viscous-inertial fluid breakup, when MBBA is in the isotropic phase, the minimum radius decreases as tau^{1.03 \\pm 0.04}. In the nematic phase however, we observe very different thinning behavior. Our measurements of the thinning profile are consistent with two interpretations. In the first interpretation, the breakup is universal and consists of two different regimes. The first regime is characterize...
Study on the breakup length of circular impinging jet
无
2007-01-01
Circular impinging jet, which is widely used in accelerated control cooling (ACC) equipment to accelerate the cooling of hot rolled plates, is subject to breakup, and may result in undesirable cooling effect. Therefore, the jet breakup should be avoided as possible in industrial production. The objective of this study is to find the relation of the processing parameters of the ACC equipment versus the breakup length of jet with weaker turbulence. To obtain quantitative findings, not only relative experimental study but also numerical simulation was carried out. For a weaker turbulent water jet, the breakup length increases with the increase of jet diameter, as well as with the jet velocity; jet diameter has a significant effect on the breakup length for a certain flow rate when compared with jet velocity; finally a suggested correlation of the jet breakup length versus jet Weber number is presented in this study.
Effects of nuclear breakup channel on fusion of 6Li+64Zn system around barrier energies
We have studied the effects of breakup, occurring due to the nuclear interaction between weakly bound 6Li and tightly bound 64Zn isotopes, on the fusion reaction at near barrier energies within the framework of dynamic polarization potential (DPP) approach. When the nuclear induced dynamic polarization potential is taken into account sub barrier enhancement and above barrier suppression have been found which improves the matching between the fusion excitation function data and predictions for 6Li+64Zn system significantly. (author)
Integral measurement of break-up excitation function using a multiple silicon telescope
A simple method is proposed for measuring the inclusive break-up excitation function which the experimental device, consisting of a set of successive silicon detectors, serves the double purpose of decreasing the incident beam energy and of detecting and identifying the reaction products. Monte Carlo simulations revealed the merits and the limitations of the method. Finally, experimental data for tritons are treated in order to obtain relevant physical informations (authors). 9 refs., 9 figs
Quantitative analysis of liquid jets breakup with SAXS
Full text: The breakup of liquid jets represents a wide area of research in the field of multiphase flows, fully justified by their wide presence both in industrial and in scientific applications. Moreover, the recent development of microfluidic systems has raised great interest in understanding the flows in small spatial dimensions. Such interest has been further increased due to the evolution of free electron lasers and the consequent need to develop new, high throughput techniques to characterize biological macromolecules. Jet instability has been widely described both theoretically and by performing simulations, however there is still need to have accurate sets of experimental data. In fact most of them are based on light scattering which is disturbed by reflection, absorption and multiple scattering of droplets and air interface morphology, and on camera imaging which is limited by the dimension of the phenomena that can be seen. In the present communication we want to show the potentiality of synchrotron SAXS in providing quantitative information on the dynamics of liquid jets at the nanoscale. To this purpose, we have investigated free liquid jets in air with circular nozzle geometry of different diameters (450μm-100μm), flow rates (2-10 ml/min), and solvents (water, ethanol, isopropanol and their mixtures). We determined their time dependent morphology and their breakup length in the Rayleigh and rst wind-induced regimes. The resulting data are considered as basis for the use of free jet micromixers to examine the evolution of chemical and biological reactions by SAXS. (author)
^{11}Li Breakup on ^{208}Pb at Energies Around the Coulomb Barrier
Fernández-García, J.P.; Cubero, M.; Rodríguez-Gallardo, M.;
2013-01-01
The inclusive breakup for the 11Li+208Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of 9Li following the 11Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbatio...
Breakup of oil droplets in turbulent flows
The oil droplets, or water-in-oil emulsions, which form after an oil is spilled at sea, were studied. The mechanism that disintegrates an oil film into droplets was critically examined. A theoretical interpretation was developed for the mechanical shear associated with small turbulent eddies. This mechanism has been suggested to be the cause of the droplet breakup. A formula for maximum droplet sizes to be expected in turbulent flows was derived. It was found that the dissipation rates required by the shear mechanism were higher than typical values found in breaking waves in the upper ocean. 27 refs., 1 tab., 3 figs
Assessment of deuteron-induced reaction mechanisms at low and medium energies
Avrigeanu V.; Avrigeanu M.
2010-01-01
An extended analysis of the nuclear reaction mechanisms involved in the deuterons interaction with 63,65Cu is presented. First, the available elastic-scattering data analysis provided us the optical potential for reaction cross sections calculations. An increased effort has been devoted to the breakup mechanism, both the elastic breakup and the breakup fusion contributions to the different activation cross sections being carefully considered. Next, the direct reaction contributions throu...
The studies on the breakup effects of weakly bound nuclei, both stable and radioactive, on fusion cross section is a subject of contemporary interest. These weakly bound nuclei have low breakup threshold (binding energy) that makes the fusion induced by these nuclei fundamentally different from that induced by tightly bound nuclei. Among these nuclei, the nucleus 9Be is very interesting because it has low break up threshold of 1.67 MeV and has a possible three body n+α+α Borromean structure. So far, numbers of experiments have been carried out to study the fusion reactions induced by 9Be on various targets at near barrier energies
24 CFR 982.315 - Family break-up.
2010-04-01
... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Family break-up. 982.315 Section... SECTION 8 TENANT BASED ASSISTANCE: HOUSING CHOICE VOUCHER PROGRAM Leasing a Unit § 982.315 Family break-up... assistance in the program if the family breaks up. The PHA administrative plan must state PHA policies on...
Breakup Effects on University Students' Perceived Academic Performance
Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette
2012-01-01
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…
Comment on breakup densities of hot nuclei
In [V.E. Viola et al., Phys. Rev. Lett. 93 (2004) 132701, D.S. Bracken et al., Phys. Rev. C 69 (2004) 034612] the observed decrease in spectral peak energies of IMFs emitted from hot nuclei was interpreted in terms of a breakup density that decreased with increasing excitation energy. Subsequently, Raduta et al. [Ad. Raduta et al., Phys. Lett. B 623 (2005) 43] performed MMM simulations that showed decreasing spectral peaks could be obtained at constant density. In this Letter we point out that this apparent inconsistency is due to a selective comparison of theory and data that overlooks the evolution of the fragment multiplicities as a function of excitation energy
Team formation and breakup in multiagent systems
Rao, Venkatesh Guru
The goal of this dissertation is to pose and solve problems involving team formation and breakup in two specific multiagent domains: formation travel and space-based interferometric observatories. The methodology employed comprises elements drawn from control theory, scheduling theory and artificial intelligence (AI). The original contribution of the work comprises three elements. The first contribution, the partitioned state-space approach is a technique for formulating and solving co-ordinated motion problem using calculus of variations techniques. The approach is applied to obtain optimal two-agent formation travel trajectories on graphs. The second contribution is the class of MixTeam algorithms, a class of team dispatchers that extends classical dispatching by accommodating team formation and breakup and exploration/exploitation learning. The algorithms are applied to observation scheduling and constellation geometry design for interferometric space telescopes. The use of feedback control for team scheduling is also demonstrated with these algorithms. The third contribution is the analysis of the optimality properties of greedy, or myopic, decision-making for a simple class of team dispatching problems. This analysis represents a first step towards the complete analysis of complex team schedulers such as the MixTeam algorithms. The contributions represent an extension to the literature on team dynamics in control theory. The broad conclusions that emerge from this research are that greedy or myopic decision-making strategies for teams perform well when specific parameters in the domain are weakly affected by an agent's actions, and that intelligent systems require a closer integration of domain knowledge in decision-making functions.
Numerical analysis of jet breakup behavior using particle method
A continuous jet changes to droplets where jet breakup occurs. In this study, two-dimensional numerical analysis of jet breakup is performed using the MPS method (Moving Particle Semi-implicit Method) which is a particle method for incompressible flows. The continuous fluid surrounding the jet is neglected. Dependencies of the jet breakup length on the Weber number and the Froude number agree with the experiment. The size distribution of droplets is in agreement with the Nukiyama-Tanasawa distribution which has been widely used as an experimental correlation. Effects of the Weber number and the Froude number on the size distribution are also obtained. (author)
Numerical analysis of jet breakup behavior using particle method
A continuous jet changes to droplets where jet breakup occurs. In this study, two-dimensional numerical analysis of jet breakup is performed using the MPS method (Moving Particle Semi-implicit Method) which is a particle method for incompressible flows. The continuous fluid surrounding the jet is neglected. Dependencies of the jet breakup length on the Waber number and the Froude number agree with the experiment. The size distribution of droplets is in agreement with the Nukiyama-Tanasawa distribution which has been widely used as an experimental correlation. Effects of the Weber number and the Froude number on the size distribution are also obtained. (author)
Numerical analysis of jet breakup behavior using particle method
A continuous jet changes to droplets where jet breakup occurs. In this study, two-dimensional numerical analysis of jet breakup is performed using the MPS method (Moving Particle Semi-implicit Method) which is a particle method for incompressible flows. The continuous fluid surrounding the jet is neglected. Dependencies of the jet breakup length on the Weber number and the Froude number agree with the experiment. The size distribution of droplets is in agreement with the Nukiyama-Tanasawa distribution that has been widely used as an experimental correlation. Effects of the Weber number and the Froude number on the size distribution are also obtained. (author)
Breakup of Spiral Waves in Coupled Hindmarsh–Rose Neurons
Breakup of spiral wave in the Hindmarsh–Rose neurons with nearest-neighbour couplings is reported. Appropriate initial values and parameter regions are selected to develop a stable spiral wave and then the Gaussian coloured noise with different intensities and correlation times is imposed on all neurons to study the breakup of spiral wave, respectively. Based on the mean field theory, the statistical factor of synchronization is defined to analyse the evolution of spiral wave. It is found that the stable rotating spiral wave encounters breakup with increasing intensity of Gaussian coloured noise or decreasing correlation time to certain threshold
Breakup of Spiral Waves in Coupled Hindmarsh-Rose Neurons
MA Jun; JIA Ya; TANG Jun; YANG Li-Jian
2008-01-01
@@ Breakup of spiral wave in the Hindmarsh-Rose neurons with nearest-neighbour couplings is reported.Appropriate initial values and parameter regions are selected to develop a stable spiral wave and then the Gauesian coloured noise with different intensities and correlation times is imposed on all neurons to study the breakup of spiral wave, respectively.Based on the mean field theory, the statistical factor of synchronization is defined to analyse the evolution of spiral wave.It is found that the stable rotating spiral wave encounters breakup with increasing intensity of Gaussian coloured noise or decreasing correlation time to certain threshold.
The TAB method for numerical calculation of spray droplet breakup
Orourke, P. J.; Amsden, A. A.
A short history is given of the major milestones in the development of the stochastic particle method for calculating liquid fuel sprays. The most recent advance has been the discovery of the importance of drop breakup in engine sprays. A new method, called TAB, for calculating drop breakup is presented. Some theoretical properties of the method are derived; its numerical implementation in the computer program KIVA is described; and comparisons are presented between TAB-method calculations and experiments and calculations using another breakup model.
Vector and tensor analyzing powers in deuteron-proton breakup
Vector and tensor analyzing powers of the 1H(d-bar,pp)n breakup reaction at 130 and 100 MeV deuteron beam energies have been measured at KVI Groningen with the use of the detection systems covering large fractions of the phase space. The high precision data are compared to the theoretical predictions based on various approaches to describe the three nucleon (3N) system dynamics. Theoretical predictions describe very well the vector analyzing power data, with no need to include any three-nucleon force effects for these observables. The tensor analyzing powers can be also very well reproduced by calculations in most of the studied region, but locally certain discrepancies are observed. At 130 MeV for Axy such discrepancies usually appear, or are enhanced, when model 3N forces (3NFs), TM99 or Urbana IX, are included. Problems of all theoretical approaches with describing Axx and Ayy are limited to very small regions of the phase space, usually characterized with the lowest relative energies of the two protons. Predicted effects of 3NFs are much lower at 100 MeV, therefore at this energy equally good consistency between the data and the calculations is obtained with or without 3NFs.
Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction
We discus recent developments in theory of high energy two-body break-up 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 between two outgoing nucleons. This final state hard rescattering can be expressed through the hard NN scattering amplitude. Within HRM we discuss hard break-up reactions involving D and 3He targets and demonstrate how these reactions are sensitive to the dynamics of hard pn and pp interaction. 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.
Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction
Sargsian, Misak
2008-10-01
We discus recent developments in theory of high energy two-body break-up 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 between two outgoing nucleons. This final state hard rescattering can be expressed through the hard NN scattering amplitude. Within HRM we discuss hard break-up reactions involving D and 3He targets and demonstrate how these reactions are sensitive to the dynamics of hard pn and pp interaction. 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.
Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction
Sargsian, Misak M
2008-01-01
We discus recent developments in theory of high energy two-body break-up 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 between two outgoing nucleons. This final state hard rescattering can be expressed through the hard NN scattering amplitude. Within HRM we discuss hard break-up reactions involving D and 3He targets and demonstrate how these reactions are sensitive to the dynamics of hard pn and pp interaction. 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 ex...
Breakup of spiral wave under different boundary conditions
Zhao Ying-Kui; Wang Guang-Rui; Chen Shi-Gang
2007-01-01
In this paper, we investigate the breakup of spiral wave under no-flux, periodic and Dirichlet boundary conditions respectively. When the parameter ε is close to a critical value for Doppler-induced wave breakup, the instability of the system caused by the boundary effect occurs in the last two cases, resulting in the breakup of spiral wave near the boundary. With our defined average order measure of spiral wave (AOMSW), we quantify the degree of order of the system when the boundary-induced breakup of spiral wave happens. By analysing the AOMSW and outer diameter R of the spiral tip orbit, it is easy to find that this boundary effect is correlated with large values of R, especially under the Dirichlet boundary condition. This correlation is nonlinear, so the AOMSW sometimes oscillates with the variation of ε.
Study on the breakup lengths of free round liquid jets
ZHU Ying; WAN Yun-xia; HUANG Yong; PENG Xin-ke
2007-01-01
An experiment was conducted to measure the breakup lengths of water jets with a high-speed video camera for Weber numbers from 0 to about 1.1 × 103. The initial jet diameters are changed from 0.3mm to 1.0mm. The results indicate that at low jet velocity the breakup lengths of the jets are increased linearly from 0 to a maximum value. At the Weber number about 20 the breakup length of the jet reaches its maximum value for different initial jet diameter. A computation based on the dispersion equation is conducted to study the relationship between the growth rate of the jet surface wave and the maximum breakup length. The computations show that the maximum growth rate for the axisymmetric surface wave has a turning point at Weber number about 20, and that agrees well with the experiments.
Capillary Breakup of a Liquid Bridge: Identifying Regimes and Transitions
Li, Yuan
2016-01-01
Computations of the breakup of a liquid bridge are used to establish the limits of applicability of similarity solutions derived for different breakup regimes. These regimes are based on particular viscous-inertial balances, that is different limits of the Ohnesorge number $Oh$. To accurately establish the transitions between regimes, the minimum bridge radius is resolved through four orders of magnitude using a purpose-built multiscale finite element method. This allows us to construct a quantitative phase diagram for the breakup phenomenon which includes the appearance of a recently discovered low-$Oh$ viscous regime. The method used to quantify the accuracy of the similarity solutions allows us to identify a number of previously unobserved features of the breakup, most notably an oscillatory convergence towards the viscous-inertial similarity solution. Finally, we discuss how the new findings open up a number of challenges for both theoretical and experimental analysis.
Vibrating Breakup of Jet for Uniform Metal Droplets
Shengdong GAO; Yingxue YAO; Chengsong CUI
2007-01-01
Uniform droplet formation from capillary stream breakup provides promising opportunities for many applications such as solder balls manufacturing, circuit board printing and rapid prototype manufacturing. In this study an apparatus capable of making monosize metal spheres by vibrating breakup has been developed. The droplets were electrically charged to avoid collision and merging with one another during flight. As a result, uniformly sized tin powders (180μm in diameter) were obtained after cooling and solidification.
Numerical simulation of mechanical breakup of river ice-cover
WANG Jun; HE Liang; CHEN Pang-pang; SUI Jueyi
2013-01-01
Ice jams and ice dams in rivers will cause significant rises of water levels.Under extreme conditions,the ice flooding during winter or early spring may occur.In this paper,by considering the fluid-solid coupling effect caused by the water and the ice cover,the mechanisms of the mechanical breakup of the river ice cover are studied.A formula is obtained for determining whether or not the mechanical breakup process would happen under the hydraulic pressure of the flow.Combined with the hydraulic model under the ice covered flow,a numerical model is built and the interaction between the discharge,the hydraulic pressure under the ice cover and the date for the mechanical breakup of the river ice cover is simulated.The simulated results of the dates for the mechanical breakup of the river ice cover agree very well with the field observations of the breakups of the river ice cover in the Hequ Reach of the Yellow River.Therefore,the numerical model might serve as a good preliminary step in studying the breakup of the river ice-cover,evidencing many important parameters that affect the ice-cover process.
Role of the direct mechanisms in the deuteron-induced surrogate reactions
Avrigeanu, M
2015-01-01
An extended analysis of the key role of direct interactions, i.e., breakup, stripping and pick-up processes, for the deuteron–induced surrogate reactions is presented. Particular comments concern the deuteron breakup which is dominant in the case of the ( d; p g ) surrogate reactions on actinides target nuclei, around the Coulomb barrier.
Proton--induced deuteron breakup at GeV energies with forward emission of a fast proton pair
Komarov, V; Kacharava, A K; Kulikov, A; Macharashvili, G; Petrus, A Yu; Rathmann, F; Seyfarth, H; Ströher, H; Uzikov, Yu N; Yaschenko, S V; Zalikhanov, B; Büscher, M; Erven, W; Hartmann, M; Khoukaz, A; Koch, R; Kurbatov, V S; Lang, N; Maier, R; Merzlyakov, S I; Mikirtychiants, S M; Müller, H; Nioradze, M S; Ohm, H; Prasuhn, D; Schieck, H P; Schleichert, R; Stein, H J; Watzlawik, K H; Zhuravlev, N Yu; Zwoll, K; Uzikov, Yu.
2003-01-01
A study of the deuteron breakup reaction $pd \\to (pp)n$ with forward emission of a fast proton pair with small excitation energy $E_{pp}<$ 3 MeV has been performed at the ANKE spectrometer at COSY--J\\"ulich. An exclusive measurement was carried out at six proton--beam energies $T_p=$~0.6,~0.7,~0.8,~0.95,~1.35, and 1.9 GeV by reconstructing the momenta of the two protons. The differential cross section of the breakup reaction, averaged up to $8^{\\circ}$ over the cm polar angle of the total momentum of the $pp$ pairs, has been obtained. Since the kinematics of this process is quite similar to that of backward elastic $pd \\to dp$ scattering, the results are compared to calculations based on a theoretical model previously applied to the $pd \\to dp$ process.
Neutron-neutron quasifree scattering in nd breakup at 10 MeV
Malone, R. C.; Crowe, B.; Crowell, A. S.; Cumberbatch, L. C.; Esterline, J. H.; Fallin, B. A.; Friesen, F. Q. L.; Han, Z.; Howell, C. R.; Markoff, D.; Ticehurst, D.; Tornow, W.; Witała, H.
2016-03-01
The neutron-deuteron (nd) breakup reaction provides a rich environment for testing theoretical models of the neutron-neutron (nn) interaction. Current theoretical predictions based on rigorous ab-initio calculations agree well with most experimental data for this system, but there remain a few notable discrepancies. The cross section for nn quasifree (QFS) scattering is one such anomaly. Two recent experiments reported cross sections for this particular nd breakup configuration that exceed theoretical calculations by almost 20% at incident neutron energies of 26 and 25 MeV [1, 2]. The theoretical values can be brought into agreement with these results by increasing the strength of the 1S0 nn potential matrix element by roughly 10%. However, this modification of the nn effective range parameter and/or the 1S0 scattering length causes substantial charge-symmetry breaking in the nucleon-nucleon force and suggests the possibility of a weakly bound di-neutron state [3]. We are conducting new measurements of the cross section for nn QFS in nd breakup. The measurements are performed at incident neutron beam energies below 20 MeV. The neutron beam is produced via the 2H(d, n)3He reaction. The target is a deuterated plastic cylinder. Our measurements utilize time-of-flight techniques with a pulsed neutron beam and detection of the two emitted neutrons in coincidence. A description of our initial measurements at 10 MeV for a single scattering angle will be presented along with preliminary results. Also, plans for measurements at other energies with broad angular coverage will be discussed.
Gómez Camacho, A.; Gomes, P. R. S.; Lubian, J.; Padrón, I.
2008-05-01
A simultaneous optical model calculation of elastic scattering, complete fusion, and breakup cross sections for energies around the Coulomb barrier is presented for reactions involving the weakly bound projectile Be9 on the medium size target Sm144. In the calculations, the nuclear polarization potential U is split into a volume part UF, which is responsible for fusion reactions, and a surface part UDR, which accounts for direct reactions. A simultaneous χ2 analysis of elastic and complete fusion data shows that the extracted optical potential parameters of the real VF and imaginary WF parts of UF and the corresponding parts VDR and WDR of UDR satisfy separately the dispersion relation. Energy-dependent forms for the fusion and direct reaction potentials indicate that, at the strong absorption radius, the direct reaction potentials dominate over the fusion potentials. Moreover, the imaginary direct reaction potential results in a rather smooth function of E around the barrier energy. These findings show that the threshold anomaly, usually present in reactions with tightly bound projectiles, is not exhibited for the system Be9+Sm144. Within this formalism, the effect of breakup reactions on complete fusion is studied by turning on and off the potentials responsible for breakup reactions.
Breakup of 42 MeV 7Li projectiles in the ﬁelds of 12C and 197Au nuclei
Dhruba Gupta; C Samanta; R Kanungo; P Basu; Subinit Roy; S Kailas; A Chatterjee; B J Roy; K Mahata; A Samant; A Shrivastava
2001-07-01
Inclusive cross sections of particles and tritons from the breakup of 42 MeV 7Li by 12C and 197Au targets are presented and analysed in the framework of the Serber model. Spectral distortions due to the targets and relevant reaction mechanisms are discussed.
Investigation on Electrostatical Breakup of Bio-Oil Droplets
John Z. Wen
2012-10-01
Full Text Available In electrostatic atomization, the input electrical energy causes breaking up of the droplet surface by utilizing a mutual repulsion of net charges accumulating on that surface. In this work a number of key parameters controlling the bio-oil droplet breakup process are identified and these correlations among the droplet size distribution, specific charges of droplets and externally applied electrical voltages are quantified. Theoretical considerations of the bag or strip breakup mechanism of biodiesel droplets experiencing electrostatic potential are compared to experimental outcomes. The theoretical analysis suggests the droplet breakup process is governed by the Rayleigh instability condition, which reveals the effects of droplets size, specific charge, surface tension force, and droplet velocities. Experiments confirm that the average droplet diameters decrease with increasing specific charges and this decreasing tendency is non-monotonic due to the motion of satellite drops in the non-uniform electrical field. The measured specific charges are found to be smaller than the theoretical values. And the energy transformation from the electrical energy to surface energy, in addition to the energy loss, Taylor instability breakup, non-excess polarization and some system errors, accounts for this discrepancy. The electrostatic force is the dominant factor controlling the mechanism of biodiesel breakup in electrostatic atomization.
Dynamics of bubble breakup at a T junction
Lu, Yutao; Fu, Taotao; Zhu, Chunying; Ma, Youguang; Li, Huai Z.
2016-02-01
The gas-liquid interfacial dynamics of bubble breakup in a T junction was investigated. Four regimes were observed for a bubble passing through the T junction. It was identified by the stop flow that a critical width of the bubble neck existed: if the minimum width of the bubble neck was less than the critical value, the breakup was irreversible and fast; while if the minimum width of the bubble neck was larger than the critical value, the breakup was reversible and slow. The fast breakup was driven by the surface tension and liquid inertia and is independent of the operating conditions. The minimum width of the bubble neck could be scaled with the remaining time as a power law with an exponent of 0.22 in the beginning and of 0.5 approaching the final fast pinch-off. The slow breakup was driven by the continuous phase and the gas-liquid interface was in the equilibrium stage. Before the appearance of the tunnel, the width of the depression region could be scaled with the time as a power law with an exponent of 0.75; while after that, the width of the depression was a logarithmic function with the time.
Resonant and nonresonant breakup of the neutron-halo nuclei 11Be and 19C from a proton target
The breakup of a halo nuclei from a stable nucleus is a sensitive tool of the reaction framework. In order to study the halo continuum, both resonant and nonresonant contributions should be taken into account. In addition a proper treatment of the few-body dynamics of the three-body problem should be accomplished in case only few degrees of freedom play a role in the reaction mechanism. Most recently, the Faddeev/AGS multiple scattering reaction formalism [1,2,3] has been applied to the study of reactions involving two-body halo nuclei [4,5,6]. These works have shown that a tighter control in the reaction theory is needed and that traditional reaction approaches may not be adequate to interpret and extract accurate and reliable structure information from the data. Our aim is to use the Faddeev/AGS scattering approach to analyse the experimental data, which unlike other approximate reaction methods provides a numerically exact solution of the underlying effective three-body Hamiltonian. We calculate inclusive breakup angular cross sections and energy spectrum observables for the scattering of one neutron-halo nuclei 11Be and 19C from a proton target at intermediate energies and compare with existing experimental data [7,8] respectively.(author)
Coulomb and nuclear breakup at low energies: Scaling laws
We report on a recent work on the low-energy behavior of the breakup cross section in so far as it has important role in the fusion of weakly bound and halo nuclei at near-barrier energies. We assess the way the nuclear component of this cross section scales with the target mass. In complete accord with previous finding at higher energies we verify that the low energy behavior of the breakup cross section for a given projectile and relative center of mass energy with respect to the Coulomb barrier height scales as the cubic root of the mass number of the target. Surprisingly we find that the Coulomb component of the breakup cross section at these low energies also obeys scaling, but with a linear dependence on the target charge. Our findings are important when planning for experiments involving these exotic nuclei. (authors)
Breakup of Droplets in Micro and Nanofluidic T-Junctions
A. bedram
2013-01-01
Full Text Available We employ numerical simulations to investigate the breakup of droplets in micro- and nanoscale T junctions, which are used to produce small droplets from a large droplet. For this purpose a Volume f Fluid (VOF based method is used and for verifying the reliability of the numerical outcomes, the results are compared with the available experimental and analytical results. Our results reveal that breakup time and breakup length of the droplets play important roles in handling these systems optimally. Our results also indicate that for nanoscale Tjunctions by increasing the capillary number the performance increases while for the micro-scale systems there is a specific capillary number for which the system is in its optimum condition.
Scaling laws for near barrier Coulomb and Nuclear Breakup
Hussein, M S; Lubian, J; Otomar, D R; Canto, L F
2013-01-01
We investigate the nuclear and the Coulomb contributions to the breakup cross sections of $^6$Li in collisions with targets in different mass ranges. Comparing cross sections for different targets at collision energies corresponding to the same $E/V_{\\mathrm{\\scriptscriptstyle B}}$, we obtain interesting scaling laws. First, we derive an approximate linear expression for the nuclear breakup cross section as a function of $A_{\\mathrm{% \\scriptscriptstyle T}}^{1/3}$. We then confirm the validity of this expression performing CDCC calculations. Scaling laws for the Coulomb breakup cross section are also investigated. In this case, our CDCC calculations indicate that this cross section has a linear dependence on the atomic number of the target. This behavior is explained by qualitative arguments. Our findings, which are consistent with previously obtained results for higher energies, are important when planning for experiments involving exotic weakly bound nuclei.
Coulomb and Nuclear Breakup at Low Energies: Scaling Laws
Hussein M. S.
2013-12-01
Full Text Available We report on a recent work on the low-energy behavior of the breakup cross section in so far as it has important role in the fusion of weakly bound and halo nuclei at near-barrier energies. We assess the way the nuclear component of this cross section scales with the target mass. In complete accord with previous finding at higher energies we verify that the low energy behavior of the breakup cross section for a given projectile and relative center of mass energy with respect to the Coulomb barrier height scales as the cubic root of the mass number of the target. Surprisingly we find that the Coulomb component of the breakup cross section at these low energies also obeys scaling, but with a linear dependence on the target charge. Our findings are important when planning for experiments involving these exotic nuclei.
Neutrino Magnetic Moment Contribution to the Neutrino-Deuteron Reaction
Tsuji, K.; Nakamura, S.; Sato, T.; Kubodera, K.; Myhrer, F.
2004-01-01
We study the effect of the neutrino magnetic moment on the neutrino-deuteron breakup reaction, using a method called the standard nuclear physics approach, which has already been well tested for several electroweak processes involving the deuteron.
New technique for high-speed microjet breakup analysis
Vago, N. [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, 1111, Budapest (Hungary); Synova SA, Ch. Dent d' Oche, 1024 Ecublens (Switzerland); Spiegel, A. [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, 1111, Budapest (Hungary); Couty, P. [Institute of Imaging and Applied Optics, Swiss Federal Institute of Technology, Lausanne, BM, 1015, Lausanne (Switzerland); Wagner, F.R.; Richerzhagen, B. [Synova SA, Ch. Dent d' Oche, 1024 Ecublens (Switzerland)
2003-10-01
In this paper we introduce a new technique for visualizing the breakup of thin high-speed liquid jets. Focused light of a He-Ne laser is coupled into a water jet, which behaves as a cylindrical waveguide until the point where the amplitude of surface waves is large enough to scatter out the light from the jet. Observing the jet from a direction perpendicular to its axis, the light that appears indicates the location of breakup. Real-time examination and also statistical analysis of the jet disruption is possible with this method. A ray tracing method was developed to demonstrate the light scattering process. (orig.)
Coincidence cross sections within the quasi free break-up model for elastic projectile break-up
Scrutinizing the basic break-up model of Serber we show that it is possible to derive the triple differential cross sections for particle-particle coincidences in analytical form. An alternative interpretation within the opaque version of the model suggests to assign these cross sections to the elastic nonresonant projectile break-up due to the nuclear interaction. Distortion effects by the Coulomb field of the target are included in analogy to the Serber model. Beside the well known single maximum in the break-up spectra double and triple peak structures appear for certain combinations of the observation angles. The model yields reasonable agreement to the given experimental data, concerning the multiple peak structure as well as the order of magnitude for the absolute normalisation. Its application comprises the region of forward emission angles, especially the angular range of the classical Coulomb deflection. (orig.)
Light particle emission and projectile breakup in 35A MeV 12C induced collisions
Inclusive spectra of p, d, t, 3He from 35A MeV 12C + C, Al, Cu, Au reactions as wll as coincidences between projectile-like fragments and light particles have been measured. The apparent temperature does not seem to depend on the size of the coincident fragment. An independent way to determine source velocities indicates that high energy protons are emitted from a source with a velocity close to half the beam velocity even in assymmetric reactions. We observed in in-plane enhancement in the azimuthal angular distributions of coincident projectile-like fragments which gets stronger with increasing mass of the triggering particle or the fragment. A discussion around momentum conservation effects shows that p * B correlations may originate form a combination of pure projectile breakup- and nucleon-nucleon quasi-elastic scattering process. The correlations observed in less peripheral collision need the introduction of a second, light particle emitting source
Gómez Camacho, A.; Gomes, P. R. S.; Lubian, J.; Aguilera, E. F.
2014-03-01
A brief description is presented of the results obtained in recent years for the simultaneous analysis of elastic and fusion cross section data of nuclear reactions for several nuclear systems with weakly bound and halo projectiles. The method used in this description, consists of simultaneously determine the parameters of fusion UF and direct reaction UDR polarization potentials of Woods-Saxon geometric shapes, that fit the elastic and fusion data. As a matter of fact, UFis an energy dependent potential, with real VF and imaginary WFcomponents, that is responsible for fusion reactions. Similarly, UDR is also energy dependent with real VDR and imaginary WDR parts, that accounts for direct reactions. A general finding for all the systems presented is that, the real and imaginary parts of the fusion potential and direct reaction potentials, are related by a dispersion relation and their energy dependence around and below the Coulomb barrier, show the so-called Breakup Threshold Anomaly. The effect of breakup reactions on fusion cross sections is studied by analyzing the separate effect of the absorption potential WDR and the fusion barrier rising produced by VDR.
Capillary breakup of suspensions near pinch-off
Mathues, Wouter; McIlroy, Claire; Harlen, Oliver G.; Clasen, Christian
2015-09-01
We present new findings on how the presence of particles alters the pinch-off dynamics of a liquid bridge. For moderate concentrations, suspensions initially behave as a viscous liquid with dynamics determined by the bulk viscosity of the suspension. Close to breakup, however, the filament loses its homogeneous shape and localised accelerated breakup is observed. This paper focuses on quantifying these final thinning dynamics for different sized particles with radii between 3 μm and 20 μm in a Newtonian matrix with volume fractions ranging from 0.02 to 0.40. The dynamics of these capillary breakup experiments are very well described by a one-dimensional model that correlates changes in thinning dynamics with the particle distribution in the filament. For all samples, the accelerated dynamics are initiated by increasing particle-density fluctuations that generate locally diluted zones. The onset of these concentration fluctuations is described by a transition radius, which scales with the particle radius and volume fraction. The thinning rate continues to increase and reaches a maximum when the interstitial fluid is thinning between two particle clusters. Contrary to previous experimental studies, we observe that the final thinning dynamics are dominated by a deceleration, where the interstitial fluid appears not to be disturbed by the presence of the particles. By rescaling the experimental filament profiles, it is shown that the pinching dynamics return to the self-similar scaling of a viscous Newtonian liquid bridge in the final moments preceding breakup.
Influence of projectile breakup on complete fusion
A Mukherjee; M K Pradhan
2010-07-01
Complete fusion excitation functions for 11,10B+159Tb and 6,7Li+159Tb have been reported at energies around the respective Coulomb barriers. The measurements show significant suppression of complete fusion cross-sections at energies above the barrier for 10B+159Tb and 6,7Li+159Tb reactions, when compared to those for 11B+159Tb. The comparison shows that the extent of suppression of complete fusion cross-sections is correlated with the -separation energies of the projectiles. Also, the measured incomplete fusion cross-sections show that the -particle emanating channel is the favoured incomplete fusion process. Inclusive measurement of the -particles produced in 6Li+159Tb reaction has been carried out. Preliminary CDCC calculations carried out to estimate the - yield following 6Li breaking up into + fail to explain the measured -yield. Transfer processes seem to be important contributors.
Analyzing powers of the deuteron-proton breakup in a wide phase space region
Deuteron-proton breakup can serve as a very rich testing ground for modern calculations based on model nucleon-nucleon interactions and including also subtle effects of the so-called three-nucleon force (3NF). In the case of experiment exploring a significant part of the phase space, data obtained for continuum of final states constitute a large base for comparisons with theoretical predictions. Moreover, studies with transversally polarized deuterons give access to two vector and three tensor analyzing powers, some of which vanish in the case of the elastic scattering process. A dedicated experiment has been performed at KVI Groningen, with the use of 130 MeV polarized deuteron beam and high acceptance position-sensitive detection system. About 800 data points have been analyzed for each spin observable: vector Ax, Ay and tensor Axx, Axy, Ayy analyzing powers of the 1H(vector (d),pp)n breakup reaction. Theoretical predictions generally describe analyzing power data quite well and the quality of description provided by various approaches is rather similar. There are, however, configurations where the agreement between the data and theory is not so satisfactory. These discrepancies are not always cured by inclusion of 3NF, what indicates incompleteness of the treatment of the spin part of three nucleon system dynamics.
Development and validation of models for bubble coalescence and breakup
A generalized model for bubble coalescence and breakup has been developed, which is based on a comprehensive survey of existing theories and models. One important feature of the model is that all important mechanisms leading to bubble coalescence and breakup in a turbulent gas-liquid flow are considered. The new model is tested extensively in a 1D Test Solver and a 3D CFD code ANSYS CFX for the case of vertical gas-liquid pipe flow under adiabatic conditions, respectively. Two kinds of extensions of the standard multi-fluid model, i.e. the discrete population model and the inhomogeneous MUSIG (multiple-size group) model, are available in the two solvers, respectively. These extensions with suitable closure models such as those for coalescence and breakup are able to predict the evolution of bubble size distribution in dispersed flows and to overcome the mono-dispersed flow limitation of the standard multi-fluid model. For the validation of the model the high quality database of the TOPFLOW L12 experiments for air-water flow in a vertical pipe was employed. A wide range of test points, which cover the bubbly flow, turbulent-churn flow as well as the transition regime, is involved in the simulations. The comparison between the simulated results such as bubble size distribution, gas velocity and volume fraction and the measured ones indicates a generally good agreement for all selected test points. As the superficial gas velocity increases, bubble size distribution evolves via coalescence dominant regimes first, then breakup-dominant regimes and finally turns into a bimodal distribution. The tendency of the evolution is well reproduced by the model. However, the tendency is almost always overestimated, i.e. too much coalescence in the coalescence dominant case while too much breakup in breakup dominant ones. The reason of this problem is discussed by studying the contribution of each coalescence and breakup mechanism at different test points. The redistribution of the
On reaction mechanisms involved in the deuteron–induced surrogate reactions
An extended analysis of the nuclear reaction mechanisms involved within deuteron interaction with nuclei, namely the breakup, stripping, pick-up, pre-equilibrium emission, and evaporation from fully equilibrated compound nucleus, is presented in order to highlight the importance of the direct mechanisms still neglected in the analysis of deuteron-induced surrogate reactions. Particularly, the dominance of the breakup mechanism at low energies around the Coulomb barrier should be considered in the case of (d,x) surrogate reactions on actinide target nuclei
On reaction mechanisms involved in the deuteron–induced surrogate reactions
Avrigeanu, M.; Avrigeanu, V.; Mănăilescu, C. [Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Bucharest-Magurele (Romania)
2015-02-24
An extended analysis of the nuclear reaction mechanisms involved within deuteron interaction with nuclei, namely the breakup, stripping, pick-up, pre-equilibrium emission, and evaporation from fully equilibrated compound nucleus, is presented in order to highlight the importance of the direct mechanisms still neglected in the analysis of deuteron-induced surrogate reactions. Particularly, the dominance of the breakup mechanism at low energies around the Coulomb barrier should be considered in the case of (d,x) surrogate reactions on actinide target nuclei.
The study of the dp{yields}ppn reaction at 500 MeV of the deuteron energy at ITS Nuclotron
Piyadin, S.M., E-mail: piyadin@jinr.ru [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Janek, M. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Physics Dept, University of Zilina, 010 26 Zilina (Slovakia); Gurchin, Yu.V.; Isupov, A.Yu. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Karachuk, J.-T. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Advanced Research Institute for Electrical Engineering, Bucharest (Romania); Khrenov, A.N.; Krasnov, V.A.; Kurilkin, A.K.; Kurilkin, P.K.; Ladygin, V.P.; Livanov, A.N. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Martinska, G. [P.J.Safarik University, Kosice (Slovakia); Reznikov, S.G. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Semenov, A.K. [Moscow University Radioelectronic and Avtomatic, Dubna, Moscow region (Russian Federation); Terekhin, A.A. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Tumanov, A.E. [Moscow University Radioelectronic and Avtomatic, Dubna, Moscow region (Russian Federation); Vasiliev, T.A. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation)
2011-10-15
The experiment on dp non-mesonic breakup at Internal Target Station at Nuclotron-M is presented. The first results on the study of the dp-breakup reaction with 500 MeV unpolarized deuteron beam are discussed. Selection procedure of useful events for the dp{yields}ppn reaction with the registration of two protons is shown.
Improvement of Jet Breakup Model in Fuel Coolant Interactions
Bang, Kwang Hyun; Kim, Kyung Kyu; Nam, Yang Ho [Korea Maritime Univ., Jinhae (Korea, Republic of)
2007-02-15
The objective of this work is to improve TRACER-II code in conjunction with the OECD SERENA project for validation of vapor explosion analysis codes. FCI breakup model is to be improved by building four-fluid multiphase flow model and existing models and experimental data are examined for the validation of the model. Four-fluid multiphase flow model has been built in TRACER-II code and jet breakup model has been included. Kelvin-Helmholtz instability is modelled for the jet side and boundary layer stripping is modelled for the jet leading edge. This work can contributes to the reduction of uncertainty in the FCI models for reactor safety analysis.
Laser-induced break-up of water jet waveguide
Couty, P.; Hoffmann, P. [EPFL/STI/IOA/Advanced Photonics Laboratory, Lausanne BM, 1015, Lausanne (Switzerland); Spiegel, A.; Vago, N. [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, 1111, Budapest (Hungary); Ugurtas, B.I. [EPFL/STI/IMHEF/Laboratory Fluid Mechanics, Lausanne, 1015, Lausanne (Switzerland)
2004-06-01
In this article, an optical method to control the break-up of high-speed liquid jets is proposed. The method consists of focusing the light of a pulsed laser source into the jet behaving as a waveguide. Experiments were performed with the help of a Q-switched frequency doubled Nd:Yag laser ({lambda}=532 nm). The jet diameter was 48 {mu}m and jet velocities from 100 to 200 m/s. To study the laser-induced water jet break-up, observations of the jet coupled with the high power laser were performed for variable coupling and jet velocity conditions. Experimentally determined wavelength and growth rate of the laser-generated disturbance were also compared with the ones predicted by linear stability theory of free jets. (orig.)
Effect of target deformation and projectile breakup in complete fusion of 6Li + 152Sm
Nuclear reaction induced by weakly bound (stable or radioactive) nuclei is a subject of current experimental and theoretical interest. Measurements of fusion cross section involving loosely bound projectile 6Li and 9Be exist with different conclusion about the enhancement or suppression of fusion cross section. Recently we have measured the fusion cross section for 6Li + 144Sm, where it has been found that there is an enhancement of fusion cross section below the barrier in comparison with single BPM calculation, where as there is an overall suppression in fusion cross section as compared to CCFULL calculation in the entire energy range measured. With this motivation, we chose a deformed target, 152Sm, with β2 = 0.24 to compare with the results of 144Sm which is a spherical target. It will also be interesting to see effect of target deformation (enhancement) versus projectile breakup (suppression) specially at subbarrier energy
Semiclassical treatment of fusion and breakup processes of ^{6,8}He halo nuclei
Majeed, Fouad A.; Abdul-Hussien, Yousif A.
2016-06-01
A semiclassical approach has been used to study the effect of channel coupling on the calculations of the total fusion reaction cross section σ _{fus}, and the fusion barrier distribution D_{fus} for the systems 6He +^{238}U and 8He +^{197}Au. Since these systems invloves light exotic nuclei, breakup states channel play an important role that should be considered in the calculations. In semiclassical treatment, the relative motion between the projectile and target nuclei is approximated by a classical trajectory while the intrinsic dynamics is handled by time-dependent quantum mechanics. The calculations of the total fusion cross section σ _{fus}, and the fusion barrier distribution D_{fus} are compared with the full quantum mechanical calculations using the coupled-channels calculations with all order coupling using the computer code and with the available experimental data.
Population of Metastable States in Stable Hafnium and Ytterbium Nuclei via Beam Break-up
The ''Chessboard'' section of the DIAMANT charged-particle array has been coupled with the AFRODITE γ-ray spectrometer at the iThemba Laboratory for Accelerator Based Sciences. Charged-particle-γ-ray coincidence data were recorded during the bombardment of a 176Yb target with a 13C beam at an energy of 90 MeV. The purpose of the investigation was to study the population of metastable states in hafium nuclei via incomplete fusion reactions in which the beam breaks up due to its α-cluster character. Of note was the observation of the band based on the Kπ = 16+, T1/2 = 31 year isomer in 178Hf to its 19+ member. Also, decays from the high-K isomeric states in 174Yb and 176Yb. which were populated via 3αxn channels, indicative of complete break-up of the 13C beam
Study on breakup behavior of molten material JET in coolant
It is important to estimate the jet breakup behavior of the molten core material jet in coolant during a core distractive accident (CDA) of a fast breeder reactor (FBR). In the present study, the molten jet of U-alloy 78 simulating the core material is injected into the water simulating the coolant. The visual data of the molten jet breakup behavior is observed by using the high-speed video camera. The front velocity of the molten jet is estimated by using the image processing technique from the visual data. It shows that the front velocity of the molten jet can be divided into three regions in time. In first region, the front velocity of the molten jet increases. In second region, the front velocity of the molten jet suddenly decreases. In third region, the front velocity of the molten jet keeps at low and steady. In first region, the column diameter of the molten jet decreases with the passage of time. At the location between first region and second region, the column of the molten jet breaks up and disappears. It is experimentally observed that the molten material column in the molten material jet from breaks up and disappears as the border time between the first and the second regions. In the present study, the jet breakup length is defined as the distance from the water surface to the location between the first and the second regions, since the main body of the molten material jet column is fragmented at the time and location. From the present experimental results, it is clarified that the jet breakup behavior depends on the injection nozzle diameter but independs on the penetration velocity of the molten material jet. The present experimental results are different from qualitative tendency of the formula by Saito at al. but are qualitatively similar by Epstein et al.. (author)
Coalescence and breakup of large droplets in turbulent channel flow
Scarbolo, Luca; Bianco, Federico; Soldati, Alfredo
2015-07-01
Coalescence and breakup of large deformable droplets dispersed in a wall-bounded turbulent flow are investigated. Droplets much larger than the Kolmogorov length scale and characterized by a broad range of surface tension values are considered. The turbulent field is a channel flow computed with pseudo-spectral direct numerical simulations, while phase interactions are described with a phase field model. Within this physically consistent framework, the motion of the interfaces, the capillary effects, and the complex topological changes experienced by the droplets are simulated in detail. An oil-water emulsion is mimicked: the fluids are considered of same density and viscosity for a range of plausible values of surface tension, resulting in a simplified system that sets a benchmark for further analysis. In the present conditions, the Weber number (We), that is, the ratio between inertia and surface tension, is a primary factor for determining the droplets coalescence rate and the occurrence of breakups. Depending on the value of We, two different regimes are observed: when We is smaller than a threshold value (We 1), a permanent dynamic equilibrium between coalescence and breakup events is established.
Hard breakup of the deuteron into two Δ isobars
We study high-energy photodisintegration of the deuteron into two Δ 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→ΔΔ 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→ΔΔ scattering. We predict that the cross section of the deuteron breakup to Δ++Δ- is 4-5 times larger than that of the breakup to the Δ+Δ0 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 Δ isobars are the result of the disintegration of the preexisting ΔΔ components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both Δ++Δ- and Δ+Δ0 channels to be similar.
Nonlinear dynamics and breakup of free-surface flows
Surface-tension-driven flows and, in particular, their tendency to decay spontaneously into drops have long fascinated naturalists, the earliest systematic experiments dating back to the beginning of the 19th century. Linear stability theory governs the onset of breakup and was developed by Rayleigh, Plateau, and Maxwell. However, only recently has attention turned to the nonlinear behavior in the vicinity of the singular point where a drop separates. The increased attention is due to a number of recent and increasingly refined experiments, as well as to a host of technological applications, ranging from printing to mixing and fiber spinning. The description of drop separation becomes possible because jet motion turns out to be effectively governed by one-dimensional equations, which still contain most of the richness of the original dynamics. In addition, an attraction for physicists lies in the fact that the separation singularity is governed by universal scaling laws, which constitute an asymptotic solution of the Navier-Stokes equation before and after breakup. The Navier-Stokes equation is thus continued uniquely through the singularity. At high viscosities, a series of noise-driven instabilities has been observed, which are a nested superposition of singularities of the same universal form. At low viscosities, there is rich scaling behavior in addition to aesthetically pleasing breakup patterns driven by capillary waves. The author reviews the theoretical development of this field alongside recent experimental work, and outlines unsolved problems. copyright 1997 The American Physical Society
Inverted Break-up Behaviour in Continuous Inkjet (CIJ) Printing
McIlroy, Claire; Harlen, Oliver; Morrison, Neil
2014-11-01
Although droplet creation during continuous jetting of Newtonian fluids has been widely studied, unsolved problems surrounding the break-up dynamics remain. Jetting through a nozzle creates a stream of liquid that is rendered unstable by surface tension. This instability creates a succession of main drops connected by thin filaments, with drop separation determined by the fastest growing wavelength. In order to control break-up and increase printing speeds, continuous inkjet (CIJ) printing exploits the effects of finite amplitude modulations in the jet velocity profile giving conditions where jet stability deviates from the usual Rayleigh behaviour. To explore these non-linear effects, we have developed a one-dimensional jetting model. In particular, we identify a modulation range for which pinching occurs upstream of the connecting filament, rather than downstream - a phenomenon we call ``inverted'' break-up. Furthermore, this behaviour can be controlled by the addition of harmonics to the initial driving signal. Our results are compared to full axisymmetric simulations in order to incorporate the effects of nozzle geometry. EPSRC Innovation in Industrial Technology.
Some features of spray breakup in effervescent atomizers
Gadgil, Hrishikesh P.; Raghunandan, B.N. [Indian Institute of Science, Department of Aerospace Engineering, Bangalore (India)
2011-02-15
The near orifice spray breakup at low GLR (gas to liquid ratio by mass) values in an effervescent atomizer is studied experimentally using water as a simulant and air as atomizing gas. From the visualizations, the near orifice spray structures are classified into three modes: discrete bubble explosions, continuous bubble explosions and annular conical spray. The breakup of the spray is quantified in terms of the mean bubble bursting distance from the orifice. The parametric study indicates that the mean bubble bursting distance mainly depends on airflow rate, jet diameter and mixture velocity. It is also observed that the jet diameter has a dominant effect on the bubble bursting distance when compared to mixture velocity at a given airflow rate. The mean bubble bursting distance is shown to be governed by a nondimensional two-phase flow number consisting of all the aforementioned parameters. The location of bubble bursting is found to be highly unsteady spatially, which is influenced by flow dynamics inside the injector. It is proposed that this unsteadiness in jet breakup length is a consequence of varying degree of bubble expansion caused due to the intermittent occurrence of single phase and two-phase flow inside the orifice. (orig.)
Salama, Ahmed; Ling, Lisa
2005-01-01
Vehicle breakup analysis has been performed for missions that may carry nuclear fuel for heating or power purposes to assess nuclear safety in case of launch failure leading to atmospheric reentry. Also, failure scenarios exist which could lead to breakup during Entry / Descent / Landing (EDL) at Mars due to off-nominal entries, with implications for planetary protection requirements. Since the Mars Science Laboratory (MSL) spacecraft may include a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), an analysis of breakup in case of launch failure is required. Also, breakup during Mars EDL due to off-nominal entries could release the RTG heat source that has implications for planetary protection requirements. This paper presents a methodology of MSL breakup analysis for launch failure with application to Mars off-nominal entry.
Elastic break-up of 156 MeV 6Li projectiles with large asymptotic relative momenta of the fragments
The triple differential cross sections for elastic break-up of 156 MeV 6Li projectiles by the reactions 208Pb (6Li, ad) 208Pbg.s., and 12C (6Li, ad) 12Cg.s. have been measured with large asymptotic relative momenta of the outgoing fragments. The data exhibit rather unfamiliar shapes of the energy spectra, often replacing the usual bell-shape distributions by double-peaked structures and varying rapidly with the relative emission angles. The origin of these features has been explored and the cross sections have been analysed on the basis of a diffractive disintegration approach. (orig.)
The Effect of Corporate Break-ups on Information Asymmetry: A Market Microstructure Analysis
Bardong, Florian; Bartram, Söhnke M.; Yadav, Pradeep K.
2006-01-01
This paper investigates the information environment during and after a corporate break-up utilizing direct measures of information asymmetry developed in the market microstructure literature. The analysis is based on all corporate break-ups in the United States in the period 1995-2005. The results document that information asymmetry declines significantly as a result of a break-up. However, this reduction takes place not at the time of its announcement or its completion, but after it has been...
Spectroscopy and break-up of low energy unbound states in 12C
The nuclear structure of 12C has been discussed since the early days of nuclear physics, but experimentally there are today still open questions about the spectroscopy of this nucleus, which hamper a clear understanding of this issue. In particular the properties of broad states just above the 3α-threshold are presently being elucidated by both theory and experiments. Since 2001 we have used the β-decays of the short lived isotopes 12N and 12B to provide new information on the 0+, 1+, and 2+ states in 12C. The main results from our first series of experiments performed at IGISOL Jyvaeskylae in 2001 and ISOLDECERN in 2002, published in [1,2,3], are: 1. The Spin-parity of the so-called 10.3 MeV state is 0+ and its shape is strongly influenced by interference with the 7.654 MeV 0+ state. 2. The breakup mechanism of the 10.3 MeV state is mainly through the 8Be ground-state, but higher energies in 8Be also contribute. 3. A (most likely) 2+ state above the so called 10.3 MeV state is populated in the β-decay of 12N. 4. A good description of the breakup spectrum of the 12.71 MeV state can be made using an R-matrix formalism taking into account the symmetrisation of the three a-particles in the final state as well as the properties of the 8Be 2+ state. 5. The consequences for the astrophysical reaction rate of the triple-a reaction has been explored. In 2004 (in Jyvaeskylae) and again in 2006 (at the KVI, The Netherlands) we have revisited these decays for the following reasons. Our first set of experiments had a poor coverage for decays where the three a-particles share the breakup energy more or less equally, and hence the extend that such channels contribute could not be accurately extracted. Also, we were unable to extract the branching ratios with which the observed states were populated from the first set of data. Preliminary results from our new experiments can be found in [4] (Jyvaeskylae) and [5] (KVI data). In the ongoing analysis it has become clear that some
What should be measured in deuteron breakup with polarized proton target
At present, two different approaches are used for interpretation of inclusive data on deuteron breakup with emission of protons-fragments at zero degree by hadrons. According to one of them the observed characteristics of this reaction (cross sections, polarization observables) are determined by the reaction mechanism and the deuteron structure at short distances (in the commonly accepted sense) plays a minor role. According to the other approach it is the deuteron structure at short distances which determines the observed trend of the data. Neither of these approaches can describe the data even qualitatively in the whole investigated region of kinematical variables, having particular success for some narrow region corresponding to long distances. Installation of the polarized proton target at LHE (Laboratory of High Energies) JINR opens an opportunity to perform a rather simple experiment which could discriminate one of these completing approaches. The idea of this experiment is discussed in the present paper. Measurement of the observable suggested here is a particular example of a general problem of a search for spin correlations in inelastic reactions between particles separated well in 4-velocity or rapidity spaces. In our particular case correlations of spin degrees of freedom between particles, one of which is in the target fragmentation region and the other belongs to the projectile fragmentation region, are discussed. 10 refs., 1 fig
Experimental study on breakup characteristics of molten jet falling in gas plenum and water pool
Akinaga, Makoto; Kurita, Tomohisa; Yokobori, Seiichi [Toshiba Corp., Kawasaki, Kanagawa (Japan)
2001-07-01
The breakup characteristics of liquid jet issuing to air plenum and flowing into liquid pool were experimentally clarified. The jet breakup behavior around air was classified varying liquid substance. The bismuth and stannum molten jet was found to maintain its original shape. Moreover, breakup behavior of this molten jet during falling into the water pool was visualized. From the lump sedimented to the bottom, break-up behavior was found to be affected by the water subcooling which determining the balance between boiling and solidifying. (author)
Experimental study on breakup characteristics of molten jet falling in gas plenum and water pool
The breakup characteristics of liquid jet issuing to air plenum and flowing into liquid pool were experimentally clarified. The jet breakup behavior around air was classified varying liquid substance. The bismuth and stannum molten jet was found to maintain its original shape. Moreover, breakup behavior of this molten jet during falling into the water pool was visualized. From the lump sedimented to the bottom, break-up behavior was found to be affected by the water subcooling which determining the balance between boiling and solidifying. (author)
Application of Multiphase Particle Methods in Atomization and Breakup Regimes of Liquid Jets
Farrokhpanah, Amirsaman
2016-01-01
Multiphase Smoothed Particle Hydrodynamics (SPH) method has been used to study the jet breakup phenomena. It has been shown that this method is well capable of capturing different jet breakup characteristics. The value obtained for critical Weber number here in transition from dripping to jetting is a very good match to available values in literature. Jet breakup lengths are also agreeing well with several empirical correlations. Successful usage of SPH, as a comparably fast CFD solver, in jet breakup analysis helps in speeding up the numerical study of this phenomenon.
Bag-breakup control of surface drag in hurricanes
Troitskaya, Yuliya; Zilitinkevich, Sergej; Kandaurov, Alexander; Ermakova, Olga; Kozlov, Dmitry; Sergeev, Daniil
2016-04-01
Air-sea interaction at extreme winds is of special interest now in connection with the problem of the sea surface drag reduction at the wind speed exceeding 30-35 m/s. This phenomenon predicted by Emanuel (1995) and confirmed by a number of field (e.g., Powell, et al, 2003) and laboratory (Donelan et al, 2004) experiments still waits its physical explanation. Several papers attributed the drag reduction to spume droplets - spray turning off the crests of breaking waves (e.g., Kudryavtsev, Makin, 2011, Bao, et al, 2011). The fluxes associated with the spray are determined by the rate of droplet production at the surface quantified by the sea spray generation function (SSGF), defined as the number of spray particles of radius r produced from the unit area of water surface in unit time. However, the mechanism of spume droplets' formation is unknown and empirical estimates of SSGF varied over six orders of magnitude; therefore, the production rate of large sea spray droplets is not adequately described and there are significant uncertainties in estimations of exchange processes in hurricanes. Herewith, it is unknown what is air-sea interface and how water is fragmented to spray at hurricane wind. Using high-speed video, we observed mechanisms of production of spume droplets at strong winds by high-speed video filming, investigated statistics and compared their efficiency. Experiments showed, that the generation of the spume droplets near the wave crest is caused by the following events: bursting of submerged bubbles, generation and breakup of "projections" and "bag breakup". Statistical analysis of results of these experiments showed that the main mechanism of spray-generation is attributed to "bag-breakup mechanism", namely, inflating and consequent blowing of short-lived, sail-like pieces of the water-surface film. Using high-speed video, we show that at hurricane winds the main mechanism of spray production is attributed to "bag-breakup", namely, inflating and
Breakup conditions of projectile spectators from dynamical observables
Begemann-Blaich, M.; Lindenstruth, V.; Pochodzalla, J. [and others
1998-03-01
Momenta and masses of heavy projectile fragments (Z {>=} 8), produced in collisions of {sup 197}Au with C, Al, Cu and Pb targets at E/A=600 MeV, were determined with the ALADIN magnetic spectrometer at SIS. Using these informations, an analysis of kinematic correlations between the two and three heaviest projectile fragments in their rest frame was performed. The sensitivity of these correlations to the conditions at breakup was verified within the schematic SOS-model. For a quantitative investigation, the data were compared to calculations with statistical multifragmentation models and to classical three-body calculations. With classical trajectory calculations, where the charges and masses of the fragments are taken from a Monte Carlo sampling of the experimental events, the dynamical observables can be reproduced. The deduced breakup parameters, however, differ considerably from those assumed in the statistical multifragmentation models which describe the charge correlations. If, on the other hand, the analysis of kinematic and charge correlations is performed for events with two and three heavy fragments produced by statistical multifragmentation codes, a good agreement with the data is found with the exception that the fluctuation widths of the intrinsic fragment energies are significantly underestimated. A new version of the multifragmentation code MCFRAG was therefore used to investigate the potential role of angular momentum at the breakup stage. If a mean angular momentum of 0.75 {Dirac_h}/nucleon is added to the system, the energy fluctuations can be reproduced, but at the same time the charge partitions are modified and deviate from the data. (orig.)
Breakup conditions of projectile spectators from dynamical observables
Momenta and masses of heavy projectile fragments (Z ≥ 8), produced in collisions of 197Au with C, Al, Cu and Pb targets at E/A=600 MeV, were determined with the ALADIN magnetic spectrometer at SIS. Using these informations, an analysis of kinematic correlations between the two and three heaviest projectile fragments in their rest frame was performed. The sensitivity of these correlations to the conditions at breakup was verified within the schematic SOS-model. For a quantitative investigation, the data were compared to calculations with statistical multifragmentation models and to classical three-body calculations. With classical trajectory calculations, where the charges and masses of the fragments are taken from a Monte Carlo sampling of the experimental events, the dynamical observables can be reproduced. The deduced breakup parameters, however, differ considerably from those assumed in the statistical multifragmentation models which describe the charge correlations. If, on the other hand, the analysis of kinematic and charge correlations is performed for events with two and three heavy fragments produced by statistical multifragmentation codes, a good agreement with the data is found with the exception that the fluctuation widths of the intrinsic fragment energies are significantly underestimated. A new version of the multifragmentation code MCFRAG was therefore used to investigate the potential role of angular momentum at the breakup stage. If a mean angular momentum of 0.75 ℎ/nucleon is added to the system, the energy fluctuations can be reproduced, but at the same time the charge partitions are modified and deviate from the data. (orig.)
Bubble breakup in two-dimensional Stokes flow
A new class of exact solutions is reported for an evolving bubble in a two-dimensional slow viscous flow. It is observed that for an expanding bubble the interface grows smoother with time, whereas the contracting-bubble solutions display a tendency to form sharp corners (''near cusps'') for small values of surface tension. In the latter case, we also obtain analytic solutions that describe bubble breakup: For a large class of initial shapes, the interface will eventually develop a thin ''neck'' whose width goes to zero before the bubble is completely removed from the liquid
Chaotic behaviour as a signal of nuclear breakup
The nuclear breakup process is studied under the assumption that the energy transfer between the target and the projectile nucleus in the peripheral collisions can induce a chaotic behaviour of the nuclear Fermi systems, provided by the matching between the Woods - Saxon wall frequency and the uni - nucleonic frequency oscillation. Such a behaviour could be emphasized by uni-nucleonic phase - space maps, Poincare maps, power spectra, autocorrelation function and Lyapunov exponents ranging the nuclear interaction time scale: 10-22 s - 10-23 s. It is also shown that this method could be applied for various different fields and problems regarding nuclear dynamics. (authors)
Investigation of the Deuteron Breakup on Proton Target in the Forward Angular Region at 130 MeV
A set of differential cross-section data of the 1H(d, pp)n breakup reaction at 130 MeV deuteron beam energy has been measured in the domain of very forward polar angles with the use of the Germanium Wall detector at the Forschungszentrum Jülich. The data obtained for over 1000 kinematical points (112 geometries) are compared with the theoretical predictions based on various models of the three-nucleon (3N) dynamics. They comprise: the realistic nucleon-nucleon potentials alone or combined with the three-nucleon force (3NF), the coupled-channel calculations with the explicit treatment of the Δ-isobar excitation and finally, the potentials derived from chiral perturbation theory. In the part of the phase space studied, the Coulomb interaction between protons has a strong impact on the differential cross section of the breakup reaction. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest. In these regions the data are well reproduced exclusively by calculations which include the electromagnetic repulsion between protons. In spite of the dominance of the Coulomb force in the phase space studied, the contribution of 3NF effects is also observed. (author)
Temporal variations in river-ice break-up over the Mackenzie River Basin, Canada
de Rham, Laurent P.; Prowse, Terry D.; Bonsal, Barrie R.
2008-02-01
SummaryFor northern and arctic regions, the spring break-up period has important socio-economic, ecological and morphological effects. While these impacts are reasonably well understood, spatial and temporal assessments of break-up timing and duration remain limited due to the lack of readily available hydrometric data. For this study, the Mackenzie River Basin (MRB) of Canada is selected as a test watershed in which the spatial and temporal aspects of observed (1913-2002) spring river-ice break-up are characterized. Data from 29 Water Survey of Canada gauging sites are used including the commonly assessed 'Last B date' (last ice effect) and two hydrometric variables extracted directly from original water-level recording charts (the timing of initiation of break-up and peak water-level during break-up). It is found that the extracted variables provide a more physically based quantitative description of the break-up season in the MRB compared to the 'Last B date' method. On average, the northwards progressing ice break-up season within the MRB lasts ∼8 weeks but historically has varied within a window representative of ∼3 months of the year. The break-up period at specific locations varies from 4 days to 4 weeks. Results also indicate an anomalous zone of earlier spring break-up in the upper Peace and Athabasca region that may be partially related to the effects of flow regulation. In addition, the Mann-Kendall test reveals significantly earlier trends in the timing of spring break-up (∼1 day/decade) in upstream portions of the major tributaries of the MRB over the period 1970-2002. While similar trends have been found for other hydroclimatic variables in the basin, this study highlights the temporal patterns and variability of the spring break-up period in the Mackenzie River system.
Role of projectile breakup effects and intrinsic degrees of freedom on fusion dynamics
Singh Gautam, Manjeet
2016-05-01
This article analyzes the fusion dynamics of loosely bound and stable projectiles with Zr-target isotopes within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model (EDWSP model). In the case of the 28Si + 90Zr reaction, the coupling to the inelastic surface excitations results in an adequate description of the observed fusion dynamics while in case of the 28Si + 94Zr reaction, the coupling to collective surface vibrational states as well as the neutron (multi-neutron) transfer channel is necessary in the coupled channel calculations to reproduce the below-barrier fusion data. However, the EDWSP model calculation provides an accurate explanation of the fusion data of 28Si + 90,94Zr reactions in the domain of the Coulomb barrier. In the fusion of the 6Li + 90Zr reaction, the inclusion of the nuclear structure degrees of freedom recovers the observed sub-barrier fusion enhancement but results in suppression of the above barrier fusion data by 34% with respect to the coupled channel calculations. Using EDWSP model calculations, this suppression factor is reduced by 14% and consequently, the above-barrier fusion data of 6Li + 90Zr reaction is suppressed by 20% with reference to the EDWSP model calculations. Such fusion suppression at above-barrier energies can be correlated with the breakup of the projectile (6Li) before reaching the fusion barrier, as a consequence of low binding energy. Supported by Dr. D. S. Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission (UGC), New Delhi, India
Break-up dynamics of fluctuating liquid threads.
Petit, Julien; Rivière, David; Kellay, Hamid; Delville, Jean-Pierre
2012-11-01
The thinning dynamics of a liquid neck before break-up, as may happen when a drop detaches from a faucet or a capillary, follows different rules and dynamic scaling laws depending on the importance of inertia, viscous stresses, or capillary forces. If now the thinning neck reaches dimensions comparable to the thermally excited interfacial fluctuations, as for nanojet break-up or the fragmentation of thermally annealed nanowires, these fluctuations should play a dominant role according to recent theory and observations. Using near-critical interfaces, we here fully characterize the universal dynamics of this thermal fluctuation-dominated regime and demonstrate that the cross-over from the classical two-fluid pinch-off scenario of a liquid thread to the fluctuation-dominated regime occurs at a well-defined neck radius proportional to the thermal length scale. Investigating satellite drop formation, we also show that at the level of the cross-over between these two regimes it is more probable to produce monodisperse droplets because fluctuation-dominated pinch-off may allow the unique situation where satellite drop formation can be inhibited. Nonetheless, the interplay between the evolution of the neck profiles from the classical to the fluctuation-dominated regime and the satellites' production remains to be clarified. PMID:23090994
Aleksandrova, A. G.; Galushina, T. Yu.
2015-12-01
The paper describes the software package developed for the numerical simulation of the breakups of natural and artificial objects and algorithms on which it is based. A new software "Numerical model of breakups" includes models of collapse of the spacecraft (SC) as a result of the explosion and collision as well as two models of the explosion of an asteroid.
Light-particle multiplicity accompanying projectile breakup at 20 MeV/A
A large-solid-angle array has been used to determine the multiplicity of Z = 1 and Z = 2 particles accompanying projectile breakup into two fragments each with 5 ≤ Z ≤ 8. The charge balance obtained shows that projectile breakup is not associated with an unusual charge transfer to the target. 13 refs., 1 fig
Coupled channels approach to the break-up in the field of a nucleus
The elastic scattering and break-up of the deuteron in the field of a nucleus is formulated in terms of coupled differential equations together with correct boundary conditions. Cross sections for the two processes are given in terms of the scattering coefficients. An approximate treatment of the Coulomb distortion in the break-up channel is suggested. (orig.)
The breakup of levitating water drops observed with a high speed camera
C. Emersic
2011-10-01
Full Text Available Collision-induced water drop breakup in a vertical wind tunnel was observed using a high speed camera for interactions between larger drop sizes (up to 7 mm diameter than have previously been experimentally observed. Three distinct collisional breakup types were observed and the drop size distributions from each were analysed for comparison with predictions of fragment distributions from larger drops by two sets of established breakup parameterisations. The observations showed some similarities with both parameterisations but also some marked differences for the breakup types that could be compared, particularly for fragments 1 mm and smaller. Modifications to the parameterisations are suggested and examined. Presented is also currently the largest dataset of bag breakup distributions observed. Differences between this and other experimental research studies and modelling parameterisations, and the associated implications for interpreting results are discussed. Additionally, the stochastic coalescence and breakup equation was solved computationally using a breakup parameterisation, and the evolving drop-size distribution for a range of initial conditions was examined. Initial cloud liquid water content was found to have the greatest influence on the resulting distribution, whereas initial drop number was found to have relatively little influence. This may have implications when considering the effect of aerosol on cloud evolution, raindrop formation and resulting drop size distributions. Calculations presented show that, using an ideal initial cloud drop-size distribution, ~1–3% of the total fragments are contributed from collisional breakup between drops of 4 and 6 mm.
Self-similar drop-size distributions produced by breakup in chaotic flows
Deformation and breakup of immiscible fluids in deterministic chaotic flows is governed by self-similar distributions of stretching histories and stretching rates and produces populations of droplets of widely distributed sizes. Scaling reveals that distributions of drop sizes collapse into two self-similar families; each family exhibits a different shape, presumably due to changes in the breakup mechanism
Unity and diversity in mixing: Stretching, diffusion, breakup, and aggregation in chaotic flows
Experiments and theory have produced a reasonably good qualitative understanding of the evolution of chaotic mixing of passive tracers, especially in two-dimensional time-periodic flow fields. Such an understanding forms a fabric for the evolution of breakup, aggregation, and diffusion-controlled reactions in more complex flows. These systems can be viewed as a population of ''microstructures'' whose behavior is dictated by iterations of a chaotic flow; microstructures break, diffuse, and aggregate, causing the population to evolve in space and time. This paper presents simple physical models for such processes. Self-similarity is common to all the problems; examples arise in the context of the distribution of stretchings within chaotic flows, in the asymptotic evolution of diffusion-reaction processes at striation thickness scales, in the equilibrium distribution of drop sizes generated upon mixing of immiscible fluids, in the equations describing mean-field kinetics of coagulation, in the sequence of actions necessary for the destruction of islands in two-dimensional flow, and in the fractal structure of clusters produced upon aggregation in chaotic flows
Kistryn, S; Bodek, K; Ciepal, I; Deltuva, A; Fonseca, A; Kalantar-Nayestanaki, N; Kis, M; Klos, B; Kozela, A; Mahjour-Shafiei, M; Micherdzinska, A; Sauer, P U; Stephan, E; Sworst, R; Zejma, J; Zipper, W; Kistryn, St.
2006-01-01
High precision cross-section data of the deuteron-proton breakup reaction at 130 MeV deuteron energy are compared with the theoretical predictions obtained with a coupled-channel extension of the CD Bonn potential with virtual Delta-isobar excitation, without and with inclusion of the long-range Coulomb force. The Coulomb effect is studied on the basis of the cross-section data set, extended in this work to about 1500 data points by including breakup geometries characterized by small polar angles of the two protons. The experimental data clearly prefer predictions obtained with the Coulomb interaction included. The strongest effects are observed in regions in which the relative energy of the two protons is the smallest.
Numerical simulation of jet breakup behavior by the lattice Boltzmann method
In order to understand the jet breakup behavior of the molten core material into coolant during a core disruptive accident (CDA) for a sodium-cooled fast reactor (SFR), we simulated the jet breakup due to the hydrodynamic interaction using the lattice Boltzmann method (LBM). The applicability of the LBM to the jet breakup simulation was validated by comparison with our experimental data. In addition, the influence of several dimensionless numbers such as Weber number and Froude number was examined using the LBM. As a result, we validated applicability of the LBM to the jet breakup simulation, and found that the jet breakup length is independent of Froude number and in good agreement with the Epstein's correlation when the jet interface becomes unstable. (author)
Benjamin J. Crowe III
2009-09-30
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.
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.
Equation of state of hot nuclei before break-up
Following the method developed by the authors, recently, the equation of state of hot nuclei (238U* in concrete) before break-up was investigated numerically. The isotherms are drawn in the plane of the general pressure P versus volume VRT. They are similar to those of Van der Waals gas. The critical temperature of phase transition should correspond to the isotherm with one truning point only. It turns out that the data of mas yield distribution can be reproduced by many pairs of parameters T and VRT (freeze-out temperature and freezeout volume) varying in certain range. For each isotherm (each T), the data are always best reproduced by the value of VRT located at the maximum general pressure within two phases coexistence region
Space debris characterization in support of a satellite breakup model
Fortson, Bryan H.; Winter, James E.; Allahdadi, Firooz A.
1992-01-01
The Space Kinetic Impact and Debris Branch began an ambitious program to construct a fully analytical model of the breakup of a satellite under hypervelocity impact. In order to provide empirical data with which to substantiate the model, debris from hypervelocity experiments conducted in a controlled laboratory environment were characterized to provide information of its mass, velocity, and ballistic coefficient distributions. Data on the debris were collected in one master data file, and a simple FORTRAN program allows users to describe the debris from any subset of these experiments that may be of interest to them. A statistical analysis was performed, allowing users to determine the precision of the velocity measurements for the data. Attempts are being made to include and correlate other laboratory data, as well as those data obtained from the explosion or collision of spacecraft in low earth orbit.
Elastic nucleon-deuteron scattering and breakup with chiral forces
Witała Henryk
2016-01-01
Full Text Available Results on three-nucleon (3N elastic scattering and breakup below the pion production threshold are discussed. The large discrepancies found between a theory based on numerical solutions of 3N Faddeev equations with standard nucleon-nucleon (NN potentials only and data point to the need for three-nucleon forces (3NF’s. This notion is supported by the fact that another possible reason for the discrepancies in elastic nucleon-deuteron (Nd scattering, relativistic effects, turned out to be small. Results for a new generation of chiral NN forces (up to N4LO together with theoretical truncation errors are shown. They support conclusions obtained with standard NN potentials
Breakup of partially wetting nanoscale nematic liquid films
Lam, Michael; Linda Cummings Collaboration; Lou Kondic Collaboration; Te-Sheng Lin Collaboration
2015-11-01
The breakup of nematic liquid crystals (NLCs) films with thicknesses less than a micrometer is studied. Particular attention is paid to the interplay between the bulk elasticity and the anchoring (boundary) conditions at the substrate and free surface. Within the framework of the long wave approximation, a fourth order nonlinear partial differential equation (PDE) is derived for the free surface height. Numerical simulations of a perturbed flat film show that, depending on the initial average thickness of the film, satellite droplets form and persist on time scales much longer than dewetting. Formulating the model in terms of an effective disjoining pressure (elastic response and van der Waals interaction), simulations further suggest that satellite droplets form when the initial average film thickness corresponds to a positive effective disjoining pressure. Our results may shed light on the so-called ''forbidden film thicknesses'' seen in experiments. Supported by NSF grant DMS-1211713.
Effect of rf structure on cumulative beam breakup
We treat the effect of rf structure of a linac beam on cumulative beam breakup in the presence of external focusing. Starting with the difference equations of Helm and Loew, we derive two forms of an exact analytic solution for coasting beams: as a sum of products of Gegenbauer polynomials involving external focusing and rf structure, and as an integral involving these same parameters. The continuous-beam limit of Neil, Hall, and Cooper is obtained as the bunch separation goes to zero. An explicit solution is presented for the steady state, including modulation of the incoming displacement, showing both stable and unstable behavior with distance. Asymptotic amplitude expressions are derived for the transient solution, which can lead to even larger beam displacements. Approximate solutions also are obtained for accelerated and decelerated beams. Comparison with numerical simulations are presented
Scattering and breakup probabilities in nuclear few-body systems
One can state that the three-body model calculations based on the solution of Faddeev-type equations have been successful in predicting scattering and breakup probabilities for the three-nucleon case as well as for the α-d system. However, much remains to be done, such as more precision experiments and the laborious critical evaluation of existing data. It would be extremely valuable to have a quick way to handle the Coulomb problem. Experiments on d-16O and d-40Ca might aid in finding a way to do this. It will still be quite some time before we can make any definite statements about the offshell effects or about three-body forces in the three-nucleon case, i e effects which are not already contained in the knowledge of the triton binding energy
Single bunch beam breakup in linacs and BNS damping
We study a single-bunch beam breakup (BBU) problem by a macro-particle model. We consider both the BBU solution and the Landau damping solution which includes the Balakin-Novokhatsky-Smirnov (BNS) damping. In the BBU solution, we get an analytic solution which includes both the Chao-Richter-Yao solution and the two-particle model solution and which agrees well with simulation. The solution can also be used in a multi-bunch case. In the Landau damping solution, we can be see the mechanism of Landau damping formally and can get some insights into BNS damping. We confirm that a two-particle model criterion for BNS damping is a good one. We expect that the two-particle model criterion is represented by the first order interaction in Landau damping solution of a macro-particle model. (author)
Considerations and calculations on the breakup of jets and drops of melt related to premixing
Buerger, M.; Berg, E. von; Buck, M. [Inst. fuer Kernenergetik und Energiesysteme (IKE), Univ. of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany)
1998-01-01
Various descriptions of jet and drop breakup are applied in premixing codes, presently. The main task is to check these descriptions over a wide range of conditions in order to assure extrapolation capabilities for the codes. Jet breakup under non-boiling conditions is relatively well described by IKEJET, based on Conte/Miles (CM) instability description and a relatively detailed stripping model, in contrast to using Kelvin/Helmholtz (KH) theory. Remaining open questions are elaborated. Especially, thick jet behavior with dominance of stripping even at small relative velocities must be distinguished from thin jets with coarse breakup. The application of IKEJET to cases with jet breakup under strong film boiling yielded significantly too little fragmentation. As a possible explanation line, multiphase effects on the wave growth and stripping are considered, due to entrainment of melt and water. Parametric checking calculations are performed with a strongly simplified approach for PREMIX and FARO experiments in order to reveal main effects and the possible physical explanation features as a basis for extended modelling. The results indicate that jet breakup may be essentially sufficient to explain the experimental behavior. Rather coalescence than further drop breakup may be expected. This is also indicated by calculations with IKE drop breakup models. (author)
Effect of Air Entrainment on Breakup of Plunging Liquid Jet into Water Pool
The steam explosion intensity is largely dependent upon the degree of volumetric fractions of melt droplets and steam in the fuel-coolant mixture. The rate of melt jet breakup and droplet sizes are, therefore, the key physical parameters in the analysis of FCIs. In a recent OECD/NEA international program SERENA, the areas where research may be needed to reduce the level of uncertainties in the code predictions have been identified. The predicted void fractions in the mixture were generally much higher than experimental data and a deficiency in melt jet breakup modeling would be one of the primary causes. In this paper, an extended study of non-boiling liquid jet breakup from the previous jet breakup experiment is reported with an emphasis on the role of air entrainment by plunging liquid jet into water pool. An improved jet breakup model is also presented with comparison to the experimental data. Non-boiling liquid jet breakup experiment was conducted and the debris size was analyzed with a new jet breakup model with an emphasis on the role of air entrainment. The predicted debris size with consideration of entrained air showed good agreement with the experimental data
Effect of Air Entrainment on Breakup of Plunging Liquid Jet into Water Pool
Kim, Hyoungtak; Bang, Kwanghyun [Korea Maritime Univ., Busan (Korea, Republic of)
2013-05-15
The steam explosion intensity is largely dependent upon the degree of volumetric fractions of melt droplets and steam in the fuel-coolant mixture. The rate of melt jet breakup and droplet sizes are, therefore, the key physical parameters in the analysis of FCIs. In a recent OECD/NEA international program SERENA, the areas where research may be needed to reduce the level of uncertainties in the code predictions have been identified. The predicted void fractions in the mixture were generally much higher than experimental data and a deficiency in melt jet breakup modeling would be one of the primary causes. In this paper, an extended study of non-boiling liquid jet breakup from the previous jet breakup experiment is reported with an emphasis on the role of air entrainment by plunging liquid jet into water pool. An improved jet breakup model is also presented with comparison to the experimental data. Non-boiling liquid jet breakup experiment was conducted and the debris size was analyzed with a new jet breakup model with an emphasis on the role of air entrainment. The predicted debris size with consideration of entrained air showed good agreement with the experimental data.
Cooley, Sarah; Pavelsky, Tamlin
2016-04-01
The annual spring breakup of river ice has important consequences for northern ecosystems and significant economic implications for Arctic industry and transportation. River ice breakup research is restricted by the sparse distribution of hydrological stations in the Arctic, where limited available data suggests a trend towards earlier ice breakup. The specific climatic mechanisms driving this trend, however, are complex and can vary both regionally and within river systems. Consequently, understanding the response of river ice processes to a warming Arctic requires simultaneous examination of spatial and temporal patterns in breakup timing. Here we present an automated algorithm for river ice breakup detection using MODIS satellite imagery that enables identification of spatial and temporal breakup patterns at large scales. We examine breakup timing on the Mackenzie, Lena, Ob' and Yenisey rivers for the period 2000-2014. First, we split each river into 10 km segments. Next, for each day of the breakup season, we classify each river pixel as snow/ice, mixed ice/water or open water based on MODIS reflectance values and remove all cloud-covered segments using the MODIS cloud product. We then define the breakup date as the first day where the segment is 75% open water. Using this method, we are able to determine breakup dates with a mean uncertainty of +/-1.3 days. We find our remotely sensed breakup dates to be highly correlated to ground breakup dates and the timing of peak discharge. All statistically significant temporal trends in breakup timing are negative, indicating an overall shift towards earlier breakup. Considerable variability in the statistical significance and magnitude of trends along each river suggests that different climatic and physiographic drivers are impacting spatial patterns in breakup. Trends detected on the lower Mackenzie corroborate recent studies indicating weakening ice resistance and earlier breakup timing near the Mackenzie Delta. In
Electron fluxes in the breakup region according to measurements at Kosmos-426
Results of electron flux measurement conducted at KOSMOS-426 satellite within magnetosphere region, where breakup propagated, are analyzed. Maximum of electron fluxes with particle isotropic pinch-angular distribution measured with different pinch-angles is recorded in breakup region. Energy spectrum of 0.25-2 MeV electrons is harded near the boundary of radiation belt. Essential decrease of the intensity within latitude narrow range is marked during breakup in E≤1 keV energy electron fluxes behind the boundary of radiation belt
Sensitivity of N/Z ratio in projectile break-up of isobaric systems
De Filippo E.
2016-01-01
Full Text Available The binary break-up of projectile-like fragments in non central heavy-ion collisions follows different decay patterns, from equilibrated emission towards dynamical (prompt fission. Recently, comparing two systems with different N/Z in the entrance channel, it has been shown that the dynamical emission cross-section is enhanced for the most neutron rich system while the statistical emission cross-section is independent from the isotopic composition. In order to understand this dependence and disentangle it from the initial size of the nuclei, we have studied the two isobaric systems 124Xe+64 Zn and 124Xe+64 Ni at 35 A MeV (InKiIsSy experiment, in comparison with the previous studied reactions (124Sn +64 Ni and 112Sn +58 Ni at the same bombarding energy. We present the first results evidencing a striking similar effect in the dynamical decay as a function of the N/Z of the target for equal size systems.
The Nd Break-Up Process in Leading Order in a Three-Dimensional Approach
Fachuddin, I; Glöckle, W; Elster, Ch.
2003-01-01
A three-dimensional approach based on momentum vectors as variables for solving the three nucleon Faddeev equation in first order is presented. The nucleon-deuteron break-up amplitude is evaluated in leading order in the NN T-matrix, which is also generated directly in three dimensions avoiding a summation of partial wave contributions. A comparison of semi-exclusive observables in the $d(p,n)pp$ reaction calculated in this scheme with those generated by a traditional partial wave expansion shows perfect agreement at lower energies. At about 200 MeV nucleon laboratory energies deviations in the peak of the cross section appear, which may indicate that special care is required in a partial wave approach for energies at and higher than 200 MeV. The role of higher order rescattering processes beyond the leading order in the NN T-matrix is investigated with the result, that at 200 MeV rescattering still provides important contributions to the cross section and certain spin observables. The influence of a relativi...
Laurent, B
2007-11-15
Correlations in light neutron-rich nuclei are of considerable importance in understanding their structure. In this context the breakup of He{sup 8} into He{sup 6} + 2n has been investigated at 15 MeV/nucleon. The measurements were undertaken using a setup composed of two detector arrays: CHARISSA to detect the charged fragments and DEMON to detect the neutrons. The interpretation of the results was facilitated using a Monte Carlo simulation which was developed to take into account the correlations, the reaction and the experimental setup. Two techniques were used to study the correlations in the breakup of He{sup 8}. The first, intensity interferometry, provides, via the construction of the neutron-neutron correlation function, for a first estimate of the source size and thus the average separation between the neutrons. The second, using Dalitz plots, allows both the neutron-neutron and core-neutron correlations to be probed. Here, sequential decay via the ground state resonance of He{sup 7} and has been found to dominate the dissociation of He{sup 8}. The spatial and temporal characteristics of the breakup of He{sup 8} have thus been deduced and a root-mean-square separation between the two valence neutrons in the continuum states was estimated to be (7.3 {+-} 0.6) fm with a time delay between their emission of (1000 {+-} 300) fm/c. (author)
Fission fragment (FF) angular distributions for 6,7Li+235,238U reactions and FF mass distributions for 6,7Li+238U reactions have been measured at energies around the Coulomb barrier and reported in earlier symposia. The aim is to investigate the effect of projectile breakup on various observables in fission reactions. Due to low breakup threshold there is a probability of breakup of the projectiles which in turn may affect the compound nucleus (CN) formation cross section. In the present study it is proposed to determine the 2 > from the measured fission fragment anisotropy and compare them with the ones obtained from coupled channels calculations to investigate the effect of projectile breakup
Gobyzov Oleg
2016-01-01
Full Text Available The present paper reports an application of optical methods, namely PIV, background-oriented-schlieren (BOS and high-magnification imaging with background illumination to study of dynamics and breakup of 10-100 μm size droplets in continuous supersonic flow terminated by a normal shock wave. Flow diagnostics was performed by means of BOS and PIV. Shadow photography allowed to specify velocity ranges for different droplet sizes and to visualize droplets dynamics and breakup modes. Features of the experimental setup and certain details of implemented measurement system are considered. Results of velocity measurements and droplets behavior, including deformation and breakup, are presented and analysis of experimental conditions and dimensionless parameters affecting the droplets behavior is performed. Distinctive features of deformation and breakup processes of submillimeter scale droplets are revealed.
Generalized breakup and coalescence models for population balance modelling of liquid-liquid flows
Traczyk, Marcin; Thompson, Chris
2015-01-01
Population balance framework is a useful tool that can be used to describe size distribution of droplets in a liquid-liquid dispersion. Breakup and coalescence models provide closures for mathematical formulation of the population balance equation (PBE) and are crucial for accu- rate predictions of the mean droplet size in the flow. Number of closures for both breakup and coalescence can be identified in the literature and most of them need an estimation of model parameters that can differ even by several orders of magnitude on a case to case basis. In this paper we review the fundamental assumptions and derivation of breakup and coalescence ker- nels. Subsequently, we rigorously apply two-stage optimization over several independent sets of experiments in order to identify model parameters. Two-stage identification allows us to estab- lish new parametric dependencies valid for experiments that vary over large ranges of important non-dimensional groups. This be adopted for optimization of parameters in breakup...
Gobyzov, Oleg; Lozhkin, Yuriy; Ryabov, Mikhail; Markovich, Dmitriy
2016-03-01
The present paper reports an application of optical methods, namely PIV, background-oriented-schlieren (BOS) and high-magnification imaging with background illumination to study of dynamics and breakup of 10-100 μm size droplets in continuous supersonic flow terminated by a normal shock wave. Flow diagnostics was performed by means of BOS and PIV. Shadow photography allowed to specify velocity ranges for different droplet sizes and to visualize droplets dynamics and breakup modes. Features of the experimental setup and certain details of implemented measurement system are considered. Results of velocity measurements and droplets behavior, including deformation and breakup, are presented and analysis of experimental conditions and dimensionless parameters affecting the droplets behavior is performed. Distinctive features of deformation and breakup processes of submillimeter scale droplets are revealed.
Belov, P. A., E-mail: pavelbelov@gmail.com; Yakovlev, S. L., E-mail: yakovlev@cph10.phys.spbu.ru [St. Petersburg State University, Department of Computational Physics (Russian Federation)
2013-02-15
The process of neutron-deuteron scattering at energies above the deuteron-breakup threshold is described within the three-body formalism of Faddeev equations. Use is made of the method of solving Faddeev equations in configuration space on the basis of expanding wave-function components in the asymptotic region in bases of eigenfunctions of specially chosen operators. Asymptotically, wave-function components are represented in the form of an expansion in an orthonormalized basis of functions depending on the hyperangle. This basis makes it possible to orthogonalize the contributions of elastic-scattering and breakup channels. The proposed method permits determining scattering and breakup parameters from the asymptotic representation of the wave function without reconstructing it over the entire configuration space. The scattering and breakup amplitudes for states of total spin S = 1/2 and 3/2 were obtained for the s-wave Faddeev equation.
Multipass beam breakup can severely limit current in superconducting linear accelerators due to the inherently high Q's of transverse deflecting modes of the rf cavities. The success of higher-order-mode damping in increasing threshold currents for the 4-pass CEBAF SRF linac design is investigated with computer modeling. This simulation is shown to be in agreement with theoretical analyses which have successfully described beam breakup in the Stanford superconducting, recirculating linac. Numerical evaluation of an analytic treatment by Gluckstern of multipass beam breakup with distributed cavities is also found to be consistent with the computer model. Application of the simulation to the design array of 400 five-cell CEBAF/Cornell cavities with measured higher-order-mode damping indicates that the beam breakup threshold current is at least an order of magnitude above the CEBAF design current of 200 μA
Is the inhibition/enhancement of fusion due to breakup still a puzzle?
The effect of breakup in the fusion cross section in terms of suppression versus enhancement, discussed in a conflicting way in the literature, is addressed. Data and theoretical predictions available in the literature are compared. Excitation functions of the sub- and near-barrier fusion cross-sections for a wide variety of light and heavy systems are presented and interpreted. We have measured fusion excitation functions and breakup correlation functions for the medium weight systems 6 Li + 59 Co and 7 Li + 59 Co. These measurements help to establish the influence of the projectile breakup on the fusion process at near-barrier energies and contribute to the determination of how the mass of the target affects the breakup role. The results indicate a light fusion enhancement at sub-barrier energies and a geometry dominated cross section at barrier energies. (author)
Measuring the area of tear film break-up by image analysis software
Pena-Verdeal, Hugo; García-Resúa, Carlos; Ramos, Lucía.; Mosquera, Antonio; Yebra-Pimentel, Eva; Giráldez, María. Jesús
2013-11-01
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 μl 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.
Sub-picosecond pulse break-up in an InGaAsP optical amplifier
Romstad, Francis Pascal
broadening and eventual break-up for input pulse energies on the order of picoJoules. This break-up is present in the gain region (6-14 dB), while for absorption (-6 dB9 and transparency, pulse narrowing by a factor of two is evidenced. We observe that not only the amplitude is modulated, but also the linear...
Ice breakup forecast in the reach of the Yellow River: the support vector machines approach
Zhou, H; Li, W.; C. Zhang; Liu, J.
2009-01-01
Accurate lead-time forecast of ice breakup is one of the key aspects for ice flood prevention and reducing losses. In this paper, a new data-driven model based on the Statistical Learning Theory was employed for ice breakup prediction. The model, known as Support Vector Machine (SVM), follows the principle that aims at minimizing the structural risk rather than the empirical risk. In order to estimate the appropriate parameters of the SVM, Multiobj...
Drag-induced breakup mechanism for droplet generation in dripping within flow focusing microfluidics
Ping Wu; Zhaofeng Luo; Zhifeng Liu; Zida Li; Chi Chen; Lili Feng; Liqun He
2015-01-01
Based on viscous drag-induced breakup mechanism, a simple model was proposed to predict the dripping drop-let size as a function of controllable parameters in flow focusing micro devices. The size of thread before breakup was also investigated through laminar flow theory. Experiments and numerical simulations by VOF are carried out simultaneously to validate the theoretical analysis, showing that droplet size decreases rapidly with the in-crease of the flow rate ratio and capil ary number.
A Genesis breakup and burnup analysis in off-nominal Earth return and atmospheric entry
Salama, Ahmed; Ling, Lisa; McRonald, Angus
2005-01-01
The Genesis project conducted a detailed breakup/burnup analysis before the Earth return to determine if any spacecraft component could survive and reach the ground intact in case of an off-nominal entry. In addition, an independent JPL team was chartered with the responsibility of analyzing several definitive breakup scenarios to verify the official project analysis. This paper presents the analysis and results of this independent team.
Aerosol cluster impact and break-up : model and implementation.
Lechman, Jeremy B.
2010-10-01
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.
Asteroid breakup linked to the Great Ordovician Biodiversification Event
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
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.
We have studied spin observables in the three-body break-up reaction in deuteron–deuteron scattering in the phase-space regime that corresponds to the quasi-free deuteron–proton scattering process with the neutron as spectator. The data are compared to measurements of the elastic deuteron–proton scattering process and state-of-the-art Faddeev calculations. The results for iT11 and T22 for the quasi-free scattering data agree very well with previously published elastic-scattering data. A significant discrepancy is found for T20, which could point to a break-down of the quasi-free assumption