Precompound decay models for medium energy nuclear reactions

International Nuclear Information System (INIS)

Blann, M.

1989-11-01

The formulations used for precompound decay models are presented and explained in terms of the physics of the intranuclear cascade model. Several features of spectra of medium energy (10--1000 MeV) reactions are summarized. Results of precompound plus evaporation calculations from the code ALICE are compared with a wide body of proton, alpha, and heavy ion induced reaction data to illustrate both the power and deficiencies of predicting yield of these reactions in the medium energy regime. 23 refs., 13 figs

Decay to Equilibrium for Energy-Reaction-Diffusion Systems

KAUST Repository

Haskovec, Jan

2018-02-06

We derive thermodynamically consistent models of reaction-diffusion equations coupled to a heat equation. While the total energy is conserved, the total entropy serves as a driving functional such that the full coupled system is a gradient flow. The novelty of the approach is the Onsager structure, which is the dual form of a gradient system, and the formulation in terms of the densities and the internal energy. In these variables it is possible to assume that the entropy density is strictly concave such that there is a unique maximizer (thermodynamical equilibrium) given linear constraints on the total energy and suitable density constraints. We consider two particular systems of this type, namely, a diffusion-reaction bipolar energy transport system, and a drift-diffusion-reaction energy transport system with confining potential. We prove corresponding entropy-entropy production inequalities with explicitly calculable constants and establish the convergence to thermodynamical equilibrium, first in entropy and later in L norm using Cziszár–Kullback–Pinsker type inequalities.

Decay to Equilibrium for Energy-Reaction-Diffusion Systems

KAUST Repository

Haskovec, Jan; Hittmeir, Sabine; Markowich, Peter A.; Mielke, Alexander

2018-01-01

We derive thermodynamically consistent models of reaction-diffusion equations coupled to a heat equation. While the total energy is conserved, the total entropy serves as a driving functional such that the full coupled system is a gradient flow. The novelty of the approach is the Onsager structure, which is the dual form of a gradient system, and the formulation in terms of the densities and the internal energy. In these variables it is possible to assume that the entropy density is strictly concave such that there is a unique maximizer (thermodynamical equilibrium) given linear constraints on the total energy and suitable density constraints. We consider two particular systems of this type, namely, a diffusion-reaction bipolar energy transport system, and a drift-diffusion-reaction energy transport system with confining potential. We prove corresponding entropy-entropy production inequalities with explicitly calculable constants and establish the convergence to thermodynamical equilibrium, first in entropy and later in L norm using Cziszár–Kullback–Pinsker type inequalities.

Enhanced emission of high-energy photons perpendicular to the reaction plane in α+Th reactions

International Nuclear Information System (INIS)

Tegner, P.; Marianski, B.; Morsch, H.P.; Rogge, M.; Bargholtz, C.; Decowski, P.; Zemlo, L.

1991-01-01

High-energy photon and neutron emission has been measured in coincidence with fission fragments in α+ 232 Th reactions at 170 MeV. From measurements parallel and perpendicular to the fission plane, anisotropies relative to the reaction plane were determined. The in-plane/out-of-plane intensity ratio is 0.72(7) for photons with energies above 20 MeV and 11(3) for neutrons at 35 MeV. The result for high-energy photons can be explained by nucleon-nucleon bremsstrahlung if the initial flow of nucleons has a correlation to the reaction plane similar to the one observed for fast neutrons

Multi-step direct reactions at low energies

International Nuclear Information System (INIS)

Marcinkowski, A.; Marianski, B.

2001-01-01

Full text: The theory of the multistep direct (MSD) reactions of Feshbach, Kerman and Koonin has for quite some time become a subject of controversy due to the bi orthogonal distorted waves involved in the transition amplitudes describing the MSD cross sections. The bi orthogonal wave functions result in non-normal DWBA matrix elements, that can be expressed in terms of normal DWBA matrix elements multiplied by the inverse elastic scattering S-matrix. It has been argued that the enhancing inverse S-factors are washed out by averaging over energy in the continuum. As a result normal DWBA matrix elements are commonly used in practical calculations. Almost all analyses of inelastic scattering and charge-exchange reactions using the DWBA matrix elements have concluded that nucleon emission at low energies can be described as one-step reaction mainly. On the other hand, it has been shown that the limits imposed by the energy weighted sum rules (EWSR's) on transition of given angular momentum transfer lead to a significant reduction of the one step cross section that can be compensated by the enhanced MSD cross sections obtained with the use of the non-normal DWBA matrix elements. Very recently the MSD theory of FKK was modified to include collective excitations and the non-normal DWBA matrix elements and the prescription for calculations of the cross sections for the MSD reactions was given. In the present paper we present the results of the modified theory used for describing the 93 Nb (n,xn) 93 Nb reaction at incident energy of 20 MeV and the 65 Cu (p,xn) 65 Zn reaction at 27 MeV. The results show enhanced contributions from two-, three- and four step reactions. We investigate the importance of the multi-phonon, multi particle hole and the mixed particle hole-phonon excitations in neutron scattering to the continuum. We also show the importance of the different sequences of collisions of the leading continuum nucleon that contribute to the MSD (p,n) reaction. When all

Low energy nuclear reaction polyplasmon postulate

Energy Technology Data Exchange (ETDEWEB)

Russell, John L. [201 Heritage Drive, Apt. 208, Canton, GA 30093 (United States)], E-mail: RUSSELLJL@aol.com

2008-11-15

An explanation is proposed for the nuclear reactions that occur in the electrolysis class of LENR processes. The proposed explanation postulates that a proton, or deuteron, dissolved in the hydrogen bearing metal cathode, absorbs its associated atomic electron to become a short lived state of the neutron with the resulting neutrino in a singular wave function centered on the neutron. The energy required to initiate this endothermic reaction is supplied either by the ion current during electrolysis type experiments, or by ion bombardment in plasma type experiments. It is the energy of this bombardment of the cathode with heavy ions that creates a coherent polyplasmon field within crystalline metallic grains that are present in the metal cathode of typical active electrolysis cells. The LENR process consists of a second order reaction mediated by a coherent plasmon field excited in the conduction electrons in a hydrogen bearing metal that is in the form of crystalline grains of the order of a few microns in dimension. The coherent plasmon field in each grain is called a polyplasmon. The metallic grains typically form during solidification of a metal, the impurities being forced to the grain surfaces. The resulting grain thus forms a resonant structure that can be filled with a number of coherent plasmons, i.e., a polyplasmon. Energy from the polyplasmon is coupled to the nucleus via electron capture by hydrogen. Because the neutrino has mass, its wave function has a second class of solutions. This description can take the form of a short lived pairing with the neutron that results from electron capture by the hydrogen nucleus. This short-lived compound particle is named the 'dion' and in the case of deuterium results in a 'dineutron'. Because the dion and dineutron are formed with essentially thermal kinetic energy, they can capture in nearby nuclei, either in hydrogen or in the host metal. Most of the resulting exothermic nuclear energy is

Low energy nuclear reaction polyplasmon postulate

International Nuclear Information System (INIS)

Russell, John L.

2008-01-01

An explanation is proposed for the nuclear reactions that occur in the electrolysis class of LENR processes. The proposed explanation postulates that a proton, or deuteron, dissolved in the hydrogen bearing metal cathode, absorbs its associated atomic electron to become a short lived state of the neutron with the resulting neutrino in a singular wave function centered on the neutron. The energy required to initiate this endothermic reaction is supplied either by the ion current during electrolysis type experiments, or by ion bombardment in plasma type experiments. It is the energy of this bombardment of the cathode with heavy ions that creates a coherent polyplasmon field within crystalline metallic grains that are present in the metal cathode of typical active electrolysis cells. The LENR process consists of a second order reaction mediated by a coherent plasmon field excited in the conduction electrons in a hydrogen bearing metal that is in the form of crystalline grains of the order of a few microns in dimension. The coherent plasmon field in each grain is called a polyplasmon. The metallic grains typically form during solidification of a metal, the impurities being forced to the grain surfaces. The resulting grain thus forms a resonant structure that can be filled with a number of coherent plasmons, i.e., a polyplasmon. Energy from the polyplasmon is coupled to the nucleus via electron capture by hydrogen. Because the neutrino has mass, its wave function has a second class of solutions. This description can take the form of a short lived pairing with the neutron that results from electron capture by the hydrogen nucleus. This short-lived compound particle is named the 'dion' and in the case of deuterium results in a 'dineutron'. Because the dion and dineutron are formed with essentially thermal kinetic energy, they can capture in nearby nuclei, either in hydrogen or in the host metal. Most of the resulting exothermic nuclear energy is absorbed in the plasmon

Energy and Molecules from Photochemical/Photocatalytic Reactions. An Overview

Directory of Open Access Journals (Sweden)

Davide Ravelli

2015-01-01

Full Text Available Photocatalytic reactions have been defined as those processes that require both a (not consumed catalyst and light. A previous definition was whether such reactions brought a system towards or away from the (thermal equilibrium. This consideration brings in the question whether a part of the photon energy is incorporated into the photochemical reaction products. Data are provided for representative organic reactions involving or not molecular catalysts and show that energy storage occurs only when a heavily strained structure is generated, and in that case only a minor part of photon energy is actually stored (ΔG up to 25 kcal·mol−1. The green role of photochemistry/photocatalysis is rather that of forming highly reactive intermediates under mild conditions.

Reaction mechanism in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Tanihata, Isao.

1982-04-01

The reaction mechanism in high energy heavy-ion collision is discussed. The discussion is mainly based on the experimental data. Empirical equations have been given for the total cross-sections of nucleus-nucleus reactions and the reaction cross-sections. These cross-sections are well described by the geometrical size of the colliding nuclei. The cross-sections are also understood by microscopic calculation. The charged particle multiplicity gives additional information about the geometrical aspect of heavy ion collision. The data suggested that the total energy, independent of projectile size, is most important for determining the multiplicity. The inclusive proton spectrum in a heavy ion collision showed two distinct regions. The one is the fragment region, and the other the participant region. The spectral shapes of inclusive pion spectra are reasonably well explained by the Coulomb interaction of pions with nuclear fragments. The high energy heavy ion reaction occurs in the overlap region of the projectile and target. This has been tested by measuring the number of participants for various reactions. The space and the time structure of the collision are also discussed in this paper as well as the dynamical aspects of the collision. (Kato, T.)

Optimal Electrical Energy Slewing for Reaction Wheel Spacecraft

Science.gov (United States)

Marsh, Harleigh Christian

The results contained in this dissertation contribute to a deeper level of understanding to the energy required to slew a spacecraft using reaction wheels. This work addresses the fundamental manner in which spacecrafts are slewed (eigenaxis maneuvering), and demonstrates that this conventional maneuver can be dramatically improved upon in regards to reduction of energy, dissipative losses, as well as peak power. Energy is a fundamental resource that effects every asset, system, and subsystem upon a spacecraft, from the attitude control system which orients the spacecraft, to the communication subsystem to link with ground stations, to the payloads which collect scientific data. For a reaction wheel spacecraft, the attitude control system is a particularly heavy load on the power and energy resources on a spacecraft. The central focus of this dissertation is reducing the burden which the attitude control system places upon the spacecraft in regards to electrical energy, which is shown in this dissertation to be a challenging problem to computationally solve and analyze. Reducing power and energy demands can have a multitude of benefits, spanning from the initial design phase, to in-flight operations, to potentially extending the mission life of the spacecraft. This goal is approached from a practical standpoint apropos to an industry-flight setting. Metrics to measure electrical energy and power are developed which are in-line with the cost associated to operating reaction wheel based attitude control systems. These metrics are incorporated into multiple families of practical high-dimensional constrained nonlinear optimal control problems to reduce the electrical energy, as well as the instantaneous power burdens imposed by the attitude control system upon the spacecraft. Minimizing electrical energy is shown to be a problem in L1 optimal control which is nonsmooth in regards to state variables as well as the control. To overcome the challenge of nonsmoothness, a

High energy photons production in nuclear reactions

International Nuclear Information System (INIS)

Nifenecker, H.; Pinston, J.A.

1990-01-01

Hard photon production, in nucleus-nucleus collisions, were studied at beam energies between 10 and 125 MeV. The main characteristics of the photon emission are deduced. They suggest that the neutron-proton collisions in the early stage of the reaction are the main source of high energy gamma-rays. An overview of the theoretical approaches is given and compared with experimental results. Theoretical attempts to include the contribution of charged pion exchange currents to photon production, in calculations of proton-nucleus-gamma and nucleus-nucleus-gamma reactions, showed suitable fitting with experimental data

Caging in high energy reactions

International Nuclear Information System (INIS)

Ache, H.J.

1977-01-01

The concept of caging high energy reactions is considered. It is noted that there is no easy and unambiguous way, short of a complete and very tedious product and mechanistic analysis, which is feasible only for very few systems, to determine the contribution made by caging. It is emphasized that some products resulting from the hot reaction with a certain substrate may be formed via caging while others are not. In research on the mechanism of caging the results of Roots work on the reactions of hot 18 F with the CF 3 CH 3 system seem to provide evidence for caging, with 18 F being the caged moiety, thus proceeding via a radical--radical recombination mechanism. Their work with H 2 S additive also seems to indicate that scavenging via hydrogen abstraction from H 2 S to form does not interfere with the radical--radical recombination consistent with Bunkers molecular approach to explain the cage effects. In other research a series of observations resulting from stereochemical and combined stereochemical density variation techniques seem to favor a caged-complex. It is clear that a more conclusive answer can only be reached by more systematic studies, utilizing the whole range of nuclear reactions such as (n,2n), (n,γ) and E.C. processes in mechanistically well defined systems to elucidate the effect of variations in the recoil energies, by carrying out studies in different solvents or host substances to assess the effect of the physical parameters, such as molecule size and intermolecular interactions on the escape probability or caging efficiencies

Photonuclear reactions at intermediate energy

International Nuclear Information System (INIS)

Koch, J.H.

1982-01-01

The dominant feature of photonuclear reactions at intermediate energies is the excitation of the δ resonance and one can therefore use such reactions to study the dynamics of δ propagation in a nucleus. Following an introductory section the author comments on photoabsorption on a single nucleon in Section II. A review of the δ-n Greens function and of the photonuclear amplitude is given in Section III. Results for photoabsorption on 4 He are shown in Section IV and compared with the data. Coherent π 0 photoproduction is discussed in Section V and calculations for 12 C are compared to recent measurements. (Auth.)

Energy gains from lattice-enabled nuclear reactions

International Nuclear Information System (INIS)

Nagel, David J.

2015-01-01

The energy gain of a system is defined as the ratio of its output energy divided by the energy provided to operate the system. Most familiar systems have energy gains less than one due to various inefficiencies. By contrast, lattice-enabled nuclear reactions (LENR) offer high energy gains. Theoretical values in excess of 1000 are possible. Energy gains over 100 have already been reported. But, they have not yet been sustained for commercially significant durations. This article summarizes the current status of LENR energy gains. (author)

Exploring Reaction Mechanism on Generalized Force Modified Potential Energy Surfaces (G-FMPES) for Diels-Alder Reaction

Science.gov (United States)

Jha, Sanjiv; Brown, Katie; Subramanian, Gopinath

We apply a recent formulation for searching minimum energy reaction path (MERP) and saddle point to atomic systems subjected to an external force. We demonstrate the effect of a loading modality resembling hydrostatic pressure on the trans to cis conformational change of 1,3-butadiene, and the simplest Diels-Alder reaction between ethylene and 1,3-butadiene. The calculated MERP and saddle points on the generalized force modified potential energy surface (G-FMPES) are compared with the corresponding quantities on an unmodified potential energy surface. Our study is performed using electronic structure calculations at the HF/6-31G** level as implemented in the AIMS-MOLPRO code. Our calculations suggest that the added compressive pressure lowers the energy of cis butadiene. The activation energy barrier for the concerted Diels-Alder reaction is found to decrease progressively with increasing compressive pressure.

Energy dissipation in the process of ternary fission in heavy nuclear reaction

International Nuclear Information System (INIS)

Li Xian; Wang Chengqian; Yan Shiwei

2015-01-01

We studied the evolution of the collective motion, interaction potential, the total kinetic and excitation energies in ternary fissions of 197 Au + 197 Au system at 15 MeV/u, and discussed energy dissipation of this reaction. Through the comparison with energy-angle correlation data in binary fissions, we preliminarily concluded that the rst fission of ternary fission was an extreme deep-inelastic process. We further analyzed the correlation of the total kinetic energy with impact parameters in both binary and ternary reactions, and found that the total energy of binary reactions systems was lost about 150 MeV more than ternary fission with small impact parameters, and with larger impact parameters the total energy of ternary reactions were lost 300 MeV more than binary reactions. (authors)

Minimum Energy Pathways for Chemical Reactions

Science.gov (United States)

Walch, S. P.; Langhoff, S. R. (Technical Monitor)

1995-01-01

Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives useful results for a number of chemically important systems. The talk will focus on a number of applications to reactions leading to NOx and soot formation in hydrocarbon combustion.

A few aspects of intermediate energy heavy ion reactions

International Nuclear Information System (INIS)

Guet, C.

1982-10-01

Some aspects of reactions induced by intermediate energy heavy ions, with a special emphasis of 85 MeV/nucleon 12 C data, are discussed and compared to low energy and relativistic energy features. Transition from mean field to independant nucleon picture is advocated by an increase of nuclear transparency illuminated by reaction cross section estimations. Projectile-like fragment distributions, while demonstrating a typical high energy fragmentation behaviour, exhibit low energy regime distortions. Light fragments, associated to large parallel momentum transfer may result from total explosion. Proton emission is investigated and discussed in terms of opposite models such as thermal equilibrium and nucleon-nucleon scattering. First pion production data are well explained by single nucleon-nucleon inelastic scattering

Nucleon charge-exchange reactions at intermediate energy

Energy Technology Data Exchange (ETDEWEB)

Alford, W.P. [Western Ontario Univ., London, ON (Canada). Dept. of Physics]|[TRIUMF, Vancouver, BC (Canada); Spicer, B.M. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1997-12-31

An historical review of the development of ideas pertaining to Gamow-Teller giant resonances is given, and a description of the emergence of techniques for the study of charge exchange reactions - particularly the technical advances which yielded the recent volume of new date. The present status of charge exchange reactions is reviewed and assessed. Evidence is presented from the {sup 14}C(p,n) reaction for the dominance of the spin-isospin component of the nucleon-nucleon interaction in intermediate energy reactions. In (p,n) reactions the Gamow-Teller giant resonance dominates the spectra, with higher multipoles contributing. By contrast, in (n,p) reactions in the heavier nuclei, the Gamow-Teller transitions are substantially Pauli-blocked and the spin dipole resonance dominates, with contributions from higher multipoles. Discussions of the multipole decomposition process, used to obtain from the data the contributions of the different multipoles, and the contributions of the multipoles, are given. 226 refs., 19 figs.

Nucleon charge-exchange reactions at intermediate energy

International Nuclear Information System (INIS)

Alford, W.P.; Spicer, B.M.

1997-01-01

An historical review of the development of ideas pertaining to Gamow-Teller giant resonances is given, and a description of the emergence of techniques for the study of charge exchange reactions - particularly the technical advances which yielded the recent volume of new date. The present status of charge exchange reactions is reviewed and assessed. Evidence is presented from the 14 C(p,n) reaction for the dominance of the spin-isospin component of the nucleon-nucleon interaction in intermediate energy reactions. In (p,n) reactions the Gamow-Teller giant resonance dominates the spectra, with higher multipoles contributing. By contrast, in (n,p) reactions in the heavier nuclei, the Gamow-Teller transitions are substantially Pauli-blocked and the spin dipole resonance dominates, with contributions from higher multipoles. Discussions of the multipole decomposition process, used to obtain from the data the contributions of the different multipoles, and the contributions of the multipoles, are given

Low Energy Nuclear Reactions?

CERN Multimedia

CERN. Geneva; Faccini, R.

2014-01-01

After an introduction to the controversial problem of Low Energy Nuclear Reactions (LENR) catalyzed by neutrons on metallic hydride surfaces we present the results of an experiment, made in collaboration with ENEA Labs in Frascati, to search neutrons from plasma discharges in electrolytic cells. The negative outcome of our experiment goes in the direction of ruling out those theoretical models expecting LENR to occur in condensed matter systems under specific conditions. Our criticism on the theoretical foundations of such models will also be presented.

Study of energy deposition in heavy-ion reactions

International Nuclear Information System (INIS)

Mota, V. De La; Abgrall, P.; Sebille, F.; Haddad, F.

1993-01-01

An investigation of energy deposition mechanisms in heavy-ion reactions at intermediate energies is presented. Theoretical simulations are performed in the framework of the semi-classical Landau-Vlasov model. They emphasize the influence of the initial non-equilibrium conditions, and the connection with the incident energy is discussed. Characteristic times involved in the energy thermalization process and finite size effects are analyzed. (authors) 20 refs., 4 figs

Novel Role of Superfluidity in Low-Energy Nuclear Reactions.

Science.gov (United States)

Magierski, Piotr; Sekizawa, Kazuyuki; Wlazłowski, Gabriel

2017-07-28

We demonstrate, within symmetry unrestricted time-dependent density functional theory, the existence of new effects in low-energy nuclear reactions which originate from superfluidity. The dynamics of the pairing field induces solitonic excitations in the colliding nuclear systems, leading to qualitative changes in the reaction dynamics. The solitonic excitation prevents collective energy dissipation and effectively suppresses the fusion cross section. We demonstrate how the variations of the total kinetic energy of the fragments can be traced back to the energy stored in the superfluid junction of colliding nuclei. Both contact time and scattering angle in noncentral collisions are significantly affected. The modification of the fusion cross section and possibilities for its experimental detection are discussed.

Computing the Free Energy along a Reaction Coordinate Using Rigid Body Dynamics.

Science.gov (United States)

Tao, Peng; Sodt, Alexander J; Shao, Yihan; König, Gerhard; Brooks, Bernard R

2014-10-14

The calculations of potential of mean force along complex chemical reactions or rare events pathways are of great interest because of their importance for many areas in chemistry, molecular biology, and material science. The major difficulty for free energy calculations comes from the great computational cost for adequate sampling of the system in high-energy regions, especially close to the reaction transition state. Here, we present a method, called FEG-RBD, in which the free energy gradients were obtained from rigid body dynamics simulations. Then the free energy gradients were integrated along a reference reaction pathway to calculate free energy profiles. In a given system, the reaction coordinates defining a subset of atoms (e.g., a solute, or the quantum mechanics (QM) region of a quantum mechanics/molecular mechanics simulation) are selected to form a rigid body during the simulation. The first-order derivatives (gradients) of the free energy with respect to the reaction coordinates are obtained through the integration of constraint forces within the rigid body. Each structure along the reference reaction path is separately subjected to such a rigid body simulation. The individual free energy gradients are integrated along the reference pathway to obtain the free energy profile. Test cases provided demonstrate both the strengths and weaknesses of the FEG-RBD method. The most significant benefit of this method comes from the fast convergence rate of the free energy gradient using rigid-body constraints instead of restraints. A correction to the free energy due to approximate relaxation of the rigid-body constraint is estimated and discussed. A comparison with umbrella sampling using a simple test case revealed the improved sampling efficiency of FEG-RBD by a factor of 4 on average. The enhanced efficiency makes this method effective for calculating the free energy of complex chemical reactions when the reaction coordinate can be unambiguously defined by a

Breakup reactions at intermediate and high energy

International Nuclear Information System (INIS)

Shotter, A.C.; Bice, A.N.

1981-01-01

Having considered some general aspects of peripheral break-up reactions involving heavy ions for the incident energy range 10-2000 MeV/A, specific experiments carried out at Berkeley in 1980 in the energy range 10-20 MeV/A are discussed. These indicate that sequential break-up processes from non-sequential inelastic processes both play significant roles in the mechanism. (UK)

Emission of high-energy, light particles from intermediate-energy heavy-ion reactions

International Nuclear Information System (INIS)

Ball, J.B.; Auble, R.L.

1982-01-01

One of the early surprises in examining reaction products from heavy ion reactions at 10 MeV/nucleon and above was the large yield of light particles emitted and the high energies to which the spectra of these particles extended. The interpretation of the origin of the high energy light ions has evolved from a picture of projectile excitation and subsequent evaporation to one of pre-equilibrium (or nonequilibrium) emission. The time scale for particle emission has thus moved from one that occurs following the initial collision to one that occurs at the very early stages of the collision. Research at ORNL on this phenomenon is reviewed

Nucleon charge exchange reaction and antiproton elastic scattering at intermediate energies

International Nuclear Information System (INIS)

Kronenfeld, J.

1985-02-01

This work treats the medium energy nuclear (p,n) charge exchange reaction to analog states and the low energy elastic scattering of antiprotons and investigates the central aspects of a microscopic theory based on multiple-scattering series which are pertinent to these reactions. A two-step term of the Distorted Wave Impulse Approximation (DWIA) in treating the (p,n) reaction, was included. For the very absorptive p-bar interaction with nuclei we conjecture that a partial infinite summation, constituing a renormalization of the single scattering term of the optical potential series provides the dominant feature of this interaction. In this work the excitation of analog states is calculated and it was found that the (p,n) reaction is described fairly well by the DWIA. In the first part of the work the (p,n) reaction in the energy range 100-200 MeV was treated. The DWIA calculations were based on eikonalization. In the second part of the work the p-barA interaction with the selfconsistent scheme mentioned above, for scattering energies 30-120 MeV, was examined. (author)

Mixed quantum-classical studies of energy partitioning in unimolecular chemical reactions

Science.gov (United States)

Bladow, Landon Lowell

A mixed quantum-classical reaction path Hamiltonian method is utilized to study the dynamics of unimolecular reactions. The method treats motion along the reaction path classically and treats the transverse vibrations quantum mechanically. The theory leads to equations that predict the disposai of the exit-channel potential energy to product translation and vibration. In addition, vibrational state distributions are obtained for the product normal modes. Vibrational excitation results from the curvature of the minimum energy reaction path. The method is applied to six unimolecular reactions: HF elimination from fluoroethane, 1,1-difluoroethane, 1,1-difluoroethene, and trifluoromethane; and HCl elimination from chloroethane and acetyl chloride. The minimum energy paths were calculated at either the MP2 or B3LYP level of theory. In all cases, the majority of the vibrational excitation of the products occurs in the HX fragment. The results are compared to experimental data and other theoretical results, where available. The best agreement between the experimental and calculated HX vibrational distributions is found for the halogenated ethanes, and the experimental deduction that the majority of the HX vibrational excitation arises from the potential energy release is supported. It is believed that the excess energy provided in experiments contributes to the poorer agreement between experiment and theory observed for HF elimination from 1,1-difluoroethene and trifluoromethane. An attempt is described to incorporate a treatment of the excess energy into the present method. However, the sign of the curvature coupling elements is then found to affect the dynamics. Overall, the method appears to be an efficient dynamical tool for modeling the disposal of the exit-channel potential energy in unimolecular reactions.

32S-induced reactions at 10 MeV/u bombarding energy

International Nuclear Information System (INIS)

Betz, J.; Graef, H.; Novotny, R.; Pelte, D.; Winkler, U.

1983-01-01

The deep-inelastic processes of the reactions 32 S+ 28 Si, sup(nat)S, 40 Ca, 58 Ni, 74 Ge are studied at 10 MeV/u bombarding energy employing a kinematical coincidence spectrometer. From the measured energies, momenta, masses and atomic numbers of two heavy fragments the corresponding parameters for the unobserved reaction products and the reaction Q-values are deduced. It is found that the reactions generally show the pattern of a normal deep-inelastic process which is followed by the evaporation of several light particles. But with much less intensities other processes also seem to occur: three-fragment excit channels and incomplete energy damping which is correlated with the emission of a few light particles of high momenta. (orig.)

Resonant Electromagnetic Interaction in Low Energy Nuclear Reactions

Science.gov (United States)

Chubb, Scott

2008-03-01

Basic ideas about how resonant electromagnetic interaction (EMI) can take place in finite solids are reviewed. These ideas not only provide a basis for conventional, electron energy band theory (which explains charge and heat transport in solids), but they also explain how through finite size effects, it is possible to create many of the kinds of effects envisioned by Giuliano Preparata. The underlying formalism predicts that the orientation of the external fields in the SPAWAR protocolootnotetextKrivit, Steven B., New Energy Times, 2007, issue 21, item 10. http://newenergytimes.com/news/2007/NET21.htm^,ootnotetextSzpak, S.; Mosier-Boss, P.A.; Gordon, F.E. Further evidence of nuclear reactions in the Pd lattice: emission of charged particles. Naturwissenschaften 94,511(2007)..has direct bearing on the emission of high-energy particles. Resonant EMI also implies that nano-scale solids, of a particular size, provide an optimal environment for initiating Low Energy Nuclear Reactions (LENR) in the PdD system.

Recent research on nuclear reaction using high-energy proton and neutron

Energy Technology Data Exchange (ETDEWEB)

Shibata, Tokushi [Tokyo Univ., Tanashi (Japan). Inst. for Nuclear Study

1997-11-01

The presently available high-energy neutron beam facilities are introduced. Then some interesting research on nuclear reaction using high-energy protons are reported such as the intermediate mass fragments emission and neutron spectrum measurements on various targets. As the important research using high-energy neutron, the (p,n) reactions on Mn, Fe, and Ni, the elastic scattering of neutrons, and the shielding experiments are discussed. (author)

Thermodynamic chemical energy transfer mechanisms of non-equilibrium, quasi-equilibrium, and equilibrium chemical reactions

International Nuclear Information System (INIS)

Roh, Heui-Seol

2015-01-01

Chemical energy transfer mechanisms at finite temperature are explored by a chemical energy transfer theory which is capable of investigating various chemical mechanisms of non-equilibrium, quasi-equilibrium, and equilibrium. Gibbs energy fluxes are obtained as a function of chemical potential, time, and displacement. Diffusion, convection, internal convection, and internal equilibrium chemical energy fluxes are demonstrated. The theory reveals that there are chemical energy flux gaps and broken discrete symmetries at the activation chemical potential, time, and displacement. The statistical, thermodynamic theory is the unification of diffusion and internal convection chemical reactions which reduces to the non-equilibrium generalization beyond the quasi-equilibrium theories of migration and diffusion processes. The relationship between kinetic theories of chemical and electrochemical reactions is also explored. The theory is applied to explore non-equilibrium chemical reactions as an illustration. Three variable separation constants indicate particle number constants and play key roles in describing the distinct chemical reaction mechanisms. The kinetics of chemical energy transfer accounts for the four control mechanisms of chemical reactions such as activation, concentration, transition, and film chemical reactions. - Highlights: • Chemical energy transfer theory is proposed for non-, quasi-, and equilibrium. • Gibbs energy fluxes are expressed by chemical potential, time, and displacement. • Relationship between chemical and electrochemical reactions is discussed. • Theory is applied to explore nonequilibrium energy transfer in chemical reactions. • Kinetics of non-equilibrium chemical reactions shows the four control mechanisms

Bibliographic survey of medium energy inclusive reaction data

International Nuclear Information System (INIS)

Arthur, E.D.; Madland, D.G.; McClellan, D.M.

1986-04-01

A bibliographic survey of inclusive reaction data (experimental and theoretical) for several projectile types having energies between 50 and 1000 MeV has been completed. Approximately one thousand references selected from this survey describe the current state of knowledge for particle-induced inclusive reaction data. The search covered data for the following projectiles: p, d, t, 3 He, 4 He, and lithium ions

(p,n) reaction at intermediate energy

International Nuclear Information System (INIS)

Goodman, C.D.

1979-01-01

The use of the (p,n) reaction in exploring effective interactions is reviewed. Some recent data on self-conjugate nuclei taken at the Indiana University Cyclotron Facility (IUCF) are presented, and the differences between low- and high-energy data are emphasized. Experimental problems and techniques used are briefly described. It is concluded that forward-angle (p,n) spectra at energies greater than 100 MeV are dominated by Gamow-Teller (GT) transitions, while Fermi transitions (IAS transitions) dominate near 45 MeV. Prominent GT transitions are expected from a pion-exchange interaction, and it is expected that OPEP is the dominant component of the interaction in the energy range of 100 to 200 MeV. 27 figures, 2 tables

Two-particle one-hole multiple-scattering contribution to 17O energies using an energy-dependent reaction matrix

International Nuclear Information System (INIS)

Bando, H.; Krenciglowa, E.M.

1976-01-01

The role of 2p1h correlations in 17 O is studied within a multiple-scattering formalism. An accurate, energy-dependent reaction matrix with orthogonalized plane-wave intermediate states is used to assess the relative importance of particle-particle and particle-hole correlations in the 17 O energies. The effect of energy dependence of the reaction matrix is closely examined. (Auth.)

Linear free energy relationships between aqueous phase hydroxyl radical reaction rate constants and free energy of activation.

Science.gov (United States)

Minakata, Daisuke; Crittenden, John

2011-04-15

The hydroxyl radical (HO(•)) is a strong oxidant that reacts with electron-rich sites on organic compounds and initiates complex radical chain reactions in aqueous phase advanced oxidation processes (AOPs). Computer based kinetic modeling requires a reaction pathway generator and predictions of associated reaction rate constants. Previously, we reported a reaction pathway generator that can enumerate the most important elementary reactions for aliphatic compounds. For the reaction rate constant predictor, we develop linear free energy relationships (LFERs) between aqueous phase literature-reported HO(•) reaction rate constants and theoretically calculated free energies of activation for H-atom abstraction from a C-H bond and HO(•) addition to alkenes. The theoretical method uses ab initio quantum mechanical calculations, Gaussian 1-3, for gas phase reactions and a solvation method, COSMO-RS theory, to estimate the impact of water. Theoretically calculated free energies of activation are found to be within approximately ±3 kcal/mol of experimental values. Considering errors that arise from quantum mechanical calculations and experiments, this should be within the acceptable errors. The established LFERs are used to predict the HO(•) reaction rate constants within a factor of 5 from the experimental values. This approach may be applied to other reaction mechanisms to establish a library of rate constant predictions for kinetic modeling of AOPs.

Overview of Light Hydrogen-Based Low Energy Nuclear Reactions

Science.gov (United States)

Miley, George H.; Shrestha, Prajakti J.

This paper reviews light water and hydrogen-based low-energy nuclear reactions (LENRs) including the different methodologies used to study these reactions and the results obtained. Reports of excess heat production, transmutation reactions, and nuclear radiation emission are cited. An aim of this review is to present a summary of the present status of light water LENR research and provide some insight into where this research is heading.

The nuclear structure and low-energy reactions (NSLER) collaboration

International Nuclear Information System (INIS)

Dean, D J

2006-01-01

The long-term vision of the Nuclear Structure and Low-Energy Reactions (NSLER) collaboration is to arrive at a comprehensive and unified description of nuclei and their reactions that is grounded in the interactions between the constituent nucleons. For this purpose, we will develop a universal energy density functional for nuclei and replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that will deliver maximum predictive power with minimal uncertainties that are well quantified. Nuclear structure and reactions play an essential role in the science to be investigated at rare isotope facilities, and in nuclear physics applications to the Science-Based Stockpile Stewardship Program, next-generation reactors, and threat reduction. We anticipate an expansion of the computational techniques and methods we currently employ, and developments of new treatments, to take advantage of petascale architectures and demonstrate the capability of the leadership class machines to deliver new science heretofore impossible

Neutron-proton bremsstrahlung from intermediate energy heavy-ion reactions as a probe of the nuclear symmetry energy?

International Nuclear Information System (INIS)

Yong, G.-C.; Li Baoan; Chen Liewen

2008-01-01

Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process pn→pnγ. Very interestingly, nevertheless, the ratio of hard photon spectra R 1/2 (γ) from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of 132 Sn + 124 Sn and 112 Sn + 112 Sn at E beam /A=50 MeV, for example, the R 1/2 (γ) displays a rise up to 15% when the symmetry energy is reduced by about 20% at ρ=1.3ρ 0 which is the maximum density reached in these reactions

Computed Potential Energy Surfaces and Minimum Energy Pathway for Chemical Reactions

Science.gov (United States)

Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

1994-01-01

Computed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NO and soot formation in hydrocarbon combustion are discussed.

Drift-tube studies of ion-molecule reactions at low collision energies

International Nuclear Information System (INIS)

Chatterjee, B.K.

1988-01-01

This thesis presents experimental studies of ion-molecule reactions at low collision energies using two drift tube mass spectrometer apparatus. The reactions studied are (i) proton transfer from HeH + to ArH + , (ii) charge and ion transfer reactions of O 2 2+ with NO, CO 2 , Ne and O 2 + ( 4 π u ) with CO 2 , (iii) oxidation reactions of Zr + and ZrO + with NO, CO 2 and O 2 , (iv) vibrational quenching reactions of H 3 + with He, (v) termolecular clustering reactions of H 2 CN + and H 2 CN + (HCN) (with He as the third body), (vi) three body association reactions of H + and D + with He (with He as the third body) and (vii) termolecular association reaction of NO + with NO (with Ne as third body). All the reactions were studied at thermal energies (at room temperature), reactions of O 2 2+ with NO and CO 2 , Zr + with NO/CO 2 /O 2 were also studied at center-of-mass energies higher than thermal and the association reactions of H 2 CN + /H 2 CN + (HCN) with HCN and H + /D + with He were studied at low temperatures. In addition, the thesis presents model calculations for the sweep-out effect which is an instrumental effect. A super Langevin rate constant is introduced which is a higher-order correction to the Langevin model. A theoretical model for the three-body ion-atom association rate constant is presented in the appendix of the thesis

Nuclear phenomena in low-energy nuclear reaction research.

Science.gov (United States)

Krivit, Steven B

2013-09-01

This is a comment on Storms E (2010) Status of Cold Fusion, Naturwissenschaften 97:861-881. This comment provides the following remarks to other nuclear phenomena observed in low-energy nuclear reactions aside from helium-4 make significant contributions to the overall energy balance; and normal hydrogen, not just heavy hydrogen, produces excess heat.

Low energy ion-molecule reactions

International Nuclear Information System (INIS)

Farrar, J.M.

1986-01-01

The authors work during the past year has focused on several problems in the condensation reactions of C + and CH 3 + with small molecules, particularly hydrocarbons. Their emphasis has been on understanding the dynamics of collision complex formation and isomerization of transient intermediates along the reaction coordinate. In many ionic reactions, intermediates having non-classical valence structures may be nearly as stable as their classical analogs, in contrast with neutral systems where the non-classical structures are much less stable. The C + + NH 3 system shows this behavior, indicating that the non-classical HCNH 2 + structure formed by insertion of C + into the N-H bond serves as a precursor to the products. N-H bond cleavage in this intermediate to form HCNH + occurs over a large barrier and occurs more readily than the 1,2 hydrogen atom shift to form the classical H 2 C = NH + intermediate. Their experimental kinetic energy distribution for this channel is consistent with the presence of a large exit channel barrier. Their recently published work on C + + H 2 O also demonstrates this phenomenon. The CHOH + hydroxycarbene cation serves as the initial intermediate and isomerization to the classical H 2 CO + cation is competitive with O-H or C-H cleavage to yield the formyl, HCO + , or isoformyl, COH + , cations. They have also completed studies on the reactions of C + with O 2 , CH 3 OH, HCN, and the two-carbon containing hydrocarbons ethane, ethylene, and acetylene

Low energy nuclear reactions: 2007 update

International Nuclear Information System (INIS)

Krivit, S. B.

2007-01-01

Introduction: This paper presents an overview of the field of low energy nuclear reactions (LENR), a branch of condensed matter nuclear science. It explains some of the various terminologies that have been used to describe this field since it debuted as 'cold fusion' in 1989. The paper also reviews some of the most interesting news and developments regarding low energy nuclear reaction experiments and theory, and some of the sociological and political trends that have affected the field over the last 18 years. It concludes with a list of resources and information for scientists, journalists and decision makers. Understanding the Nature of the Reactions The worldwide LENR research effort includes 200 researchers in 13 nations. Over the last 18 years, 12 international conferences have been held, as well as 7 regional conferences in Italy, 14 in Russia and 7 in Japan. The significant questions that face this field of research are: a) Are LENRs a genuine nuclear reaction? b) If so, is there a release of excess energy? and c) Are transmutations possible? If the answers to these questions turn out to be positive, the next questions will be: d) Is the energy release cost-effective? and e) Are the transmutations useful? Despite the fact that repeatability and reproducibility are challenging, the required parameters for achieving the excess heat effect are well understood. First, a high atomic loading ratio of D into Pd is required. In most conditions, 0.90 is the minimum threshold required to produce an excess heat effect. Second, a high electrical current density in the cathode is needed, 250 mA/cm 2 under most conditions. The third requirement is for some kind of dynamic trigger to impose a deuterium flux in, on or around the cathode. The challenge that researchers face is how to achieve these conditions. Some of the Most Interesting Research Developments Work by Stanislaw Szpak, Pamela Boss and Frank Gordon at the U.S. Navy's SPAWAR Systems Center in San Diego has

Total cross-sections for reactions of high energy particles (including elastic, topological, inclusive and exclusive reactions). Subvol. b

International Nuclear Information System (INIS)

Schopper, H.; Moorhead, W.G.; Morrison, D.R.O.

1988-01-01

The aim of this report is to present a compilation of cross-sections (i.e. reaction rates) of elementary particles at high energy. The data are presented in the form of tables, plots and some fits, which should be easy for the reader to use and may enable him to estimate cross-sections for presently unmeasured energies. We have analyzed all the data published in the major Journals and Reviews for momenta of the incoming particles larger than ≅ 50 MeV/c, since the early days of elementary particle physics and, for each reaction, we have selected the best cross-section data available. We have restricted our attention to integrated cross-sections, such as total cross-sections, exclusive and inclusive cross-sections etc., at various incident beam energies. We have disregarded data affected by geometrical and/or kinematical cuts which would make them not directly comparable to other data at different energies. Also, in the case of exclusive reactions, we have left out data where not all of the particles in the final state were unambiguously identified. This work contains reactions induced by neutrinos, gammas, charged pions, kaons, nucleons, antinucleons and hyperons. (orig./HSI)

Activation measurements of α-induced reactions at sub-Coulomb energies

Energy Technology Data Exchange (ETDEWEB)

Scholz, Philipp; Dewald, Alfred; Heinze, Stefan; Mayer, Jan; Mueller-Gatermann, Claus; Netterdon, Lars; Zilges, Andreas [Institute for Nuclear Physics, University of Cologne (Germany); Endres, Anne [Institute for Applied Physics, Goethe University Frankfurt am Main (Germany)

2015-07-01

Network calculations of the γ process rely almost completely on theoretically predicted reaction rates within the scope of the Hauser-Feshbach Statistical Model. Especially the prediction of cross sections for (γ,α)-reactions at energies within or close to the astrophysically relevant energy window remains a problem due to the uncertainties in the underlying α-optical-model potentials. Although experimental values far above the Coulomb-barrier are well reproduced, commonly used α-optical potentials often fail to describe the trend at energies comparable to those at astrophysical sites of the γ process. Improvements of the adopted optical-model potentials are hampered by the lack of experimental cross sections at sub-Coulomb energies. In order to enlarge the experimental data base, cross sections of the {sup 187}Re(α,n) and {sup 108}Cd(α,n) reactions were investigated using the activation technique with the Cologne Clover Counting Setup. Besides recent experimental results, future plans for more sensitive cross-section studies applying Accelerator Mass Spectrometry using CologneAMS are presented.

Statistical analysis of activation and reaction energies with quasi-variational coupled-cluster theory

Science.gov (United States)

Black, Joshua A.; Knowles, Peter J.

2018-06-01

The performance of quasi-variational coupled-cluster (QV) theory applied to the calculation of activation and reaction energies has been investigated. A statistical analysis of results obtained for six different sets of reactions has been carried out, and the results have been compared to those from standard single-reference methods. In general, the QV methods lead to increased activation energies and larger absolute reaction energies compared to those obtained with traditional coupled-cluster theory.

Origins of the Unfavorable Activation and Reaction Energies of 1-Azadiene Heterocycles Compared to 2-Azadiene Heterocycles in Diels-Alder Reactions.

Science.gov (United States)

Fell, Jason S; Martin, Blanton N; Houk, K N

2017-02-17

The reactivities of butadiene, cyclopentadiene, furan, thiophene, pyrrole, and their 1-aza- and 2-aza-derivatives in Diels-Alder reactions with ethylene and fumaronitrile were investigated with density functional theory (M06-2X/6-311G(d,p)). The activation free energies for the Diels-Alder reactions of cyclic 1-azadienes are 10-14 kcal mol -1 higher than those of cyclic 2-azadienes, and the reaction free energies are 17-20 kcal mol -1 more endergonic. The distortion/interaction model shows that the increased activation energies of cyclic 1-azadienes originate from increased transition state distortion energies and unfavorable interaction energies, arising from addition to the nitrogen terminus of the C═N bond.

Low-Energy Nuclear Reactions of Protons in Host Metals at Picometre Distance

International Nuclear Information System (INIS)

Heinrich Hora; George H. Miley; Jak C. Kelly

2000-01-01

A review is given for the explanation of the measurements of Miley (et al.) of a fully reproducible generation of nuclei of the whole periodic table by protons in host metals during a several-weeks reaction. Similar low-energy nuclear reactions (LENR) were observed by other groups. The fact that the heavy nuclides are not due to pollution can be seen from the fact that such very rare elements as thulium and terbium were detected by unique K-shell X-ray spectra. The nuclear reaction energy goes into the heavy nuclei as measured from much bigger traces in CR39 than from alphas. The fact that any reaction of the protons results in stable daughter nuclei is confirmed by the fact that the highest energy gain is resulting with stable reaction products. This has been explained in Ref. 2, and the energy gain for the heavy element generation by a compound reaction was discussed. The explanation is based on the model of the authors from 1989 to assume free motion of the protons contrary to localized crystalline states. A relation of the reaction time U on distance d of the reacting nuclei by a power law with an exponent 34.8 was derived. Based on few reproducible D-D reactions, a reaction time near the range of megaseconds and a reaction distance of nanometers was concluded. A splendid confirmation of the picometre-megasecond reactions was achieved by Li (et al.) from his direct quantum mechanical calculations of the hot fusion D-T reactions based on a one-step selective resonance tunneling model. Li (et al.) were able for the first time to derive the cross sections of the hot fusion. Li's application to picometre distance showed megasecond reaction times with no neutron or gamma emission. Because of the imaginary part in the Schroedinger potential, the problem of the level width is reduced by damping

Reversible aqueous zinc/manganese oxide energy storage from conversion reactions

Energy Technology Data Exchange (ETDEWEB)

Pan, Huilin; Shao, Yuyan; Yan, Pengfei; Cheng, Yingwen; Han, Kee Sung; Nie, Zimin; Wang, Chongmin; Yang, Jihui; Li, Xiaolin; Bhattacharya, Priyanka; Mueller, Karl T.; Liu, Jun

2016-04-18

Rechargeable aqueous batteries are attracting growing interest for energy storage due to their low cost and high safety. Fundamental understanding of highly reversible aqueous reactions is critical for building high-performance batteries. Herein, we studied the reversibility of Zn/MnO2 battery chemistry in mild aqueous MnSO4 electrolytes. α-MnO2 nanofibers were used as a high performance cathode. Our study provides good evidence for a conversion reaction mechanism through reversible formation of short nanorods and nanoparticle aggregates. This reversible conversion reaction provides an operating voltage of 1.44 V, high capacity of 285 mAh g-1, excellent rate and capacity retention of 92% after 5000 cycles. Zn metal anode also shows high reversibility in the mild aqueous MnSO4 electrolytes. The highly reversible and stable chemistries in aqueous Zn/MnO2 batteries open new opportunity for energy storage technologies with potentially high energy density, high safety, and low cost.

Nanoscopic analysis using Maruhn-Greiner theory by energy based variables in lattice for low energy nuclear reactions (LENRs)

International Nuclear Information System (INIS)

Cho, Hyo Sung; WooTae Ho

2016-01-01

Maruhn-Greiner theory is investigated for the low energy nuclear reactions (LENRs) in the aspect of the energy productions. Conventional nuclear reactions could give the hints in another kind of the nuclear theoretical utilizations. The results of simulations show the ranges of the configurations for H-ion to Pd with 10; 000 ions as 10 and 180 keV. The most probable ranges are 30 and 600 nanometers respectively. In the simulation result of broad energy regions, the cutoff energy, 350 keV , is very significant in analyzing the LENR, because the range usually depends on the entering particle, target particle, and energy of the entering particle. Therefore, the 350 keV shows there is priority for hydrogen interaction from the energy. In the analysis, the water (H_2O) has the better possibility in LENR after the 350 keV . Following the simulation for searching LENRs, the possible conditions that include the energy based variables of atomic ranges, Debye length, and reaction time has been investigated for the designed energy productions

Energy spectrum of 208Pb(n,x) reactions

Science.gov (United States)

Tel, E.; Kavun, Y.; Özdoǧan, H.; Kaplan, A.

2018-02-01

Fission and fusion reactor technologies have been investigated since 1950's on the world. For reactor technology, fission and fusion reaction investigations are play important role for improve new generation technologies. Especially, neutron reaction studies have an important place in the development of nuclear materials. So neutron effects on materials should study as theoretically and experimentally for improve reactor design. For this reason, Nuclear reaction codes are very useful tools when experimental data are unavailable. For such circumstances scientists created many nuclear reaction codes such as ALICE/ASH, CEM95, PCROSS, TALYS, GEANT, FLUKA. In this study we used ALICE/ASH, PCROSS and CEM95 codes for energy spectrum calculation of outgoing particles from Pb bombardment by neutron. While Weisskopf-Ewing model has been used for the equilibrium process in the calculations, full exciton, hybrid and geometry dependent hybrid nuclear reaction models have been used for the pre-equilibrium process. The calculated results have been discussed and compared with the experimental data taken from EXFOR.

S-factor for radiative capture reactions for light nuclei at astrophysical energies

Science.gov (United States)

Ghasemi, Reza; Sadeghi, Hossein

2018-06-01

The astrophysical S-factors of thermonuclear reactions, including radiative capture reactions and their analysis in the frame of different theoretical models, are the main source of nuclear processes. We have done research on the radiative capture reactions importance in the framework of a potential model. Investigation of the reactions in the astrophysical energies is of great interest in the aspect of astrophysics and nuclear physics for developing correct models of burning and evolution of stars. The experimental measurements are very difficult and impossible because of these reactions occurrence at low-energies. In this paper we do a calculation on radiative capture astrophysical S-factors for nuclei in the mass region A theoretical methods.

Macroscopic/microscopic simulation of nuclear reactions at intermediate energies

International Nuclear Information System (INIS)

Lacroix, D.; Van Lauwe, A.; Durand, D.

2003-01-01

An event generator, HIPSE (Heavy-Ion Phase-Space Exploration), dedicated to the description of nuclear collisions in the intermediate energy range is presented. The model simulates events for reactions close to the fusion barrier (5-10 MeV/A) up to higher energy (100 MeV/A) and it gives access to the phase-space explored during the collision. The development of HIPSE has been largely influenced by experimental observations. We have separated the reaction into 4 steps: contact, fragment formation, chemical freeze-out, and in-flight deexcitation. HIPSE will be useful for a study of various mechanisms such as neck fragmentation or multi-fragmentation

Characterization of low energy radioactive beams using direct reactions

DEFF Research Database (Denmark)

Johansen, J.G.; Fraser, M.A.; Bildstein, V.

2013-01-01

We demonstrate a new technique to determine the beam structure of low energy radioactive beams using coincidence events from a direct reaction. The technique will be described and tested using Geant4 simulations. We use the technique to determine for the first time the width, divergence and energy...

Low-energy nuclear reactions with double-solenoid- based ...

Indian Academy of Sciences (India)

solenoids to produce low-energy radioactive nuclear beams. In these systems the ... For many years, the disadvantage in these investigations ... fusion or breakup reaction, preferred with large forward-peaked cross-sections. To transfer the ...

Free energy for protonation reaction in lithium-ion battery cathode materials

International Nuclear Information System (INIS)

Benedek, R.; Thackeray, M. M.; van de Walle, A.

2008-01-01

Calculations are performed of free energies for proton-for-lithium-ion exchange reactions in lithium-ion battery cathode materials. First-principles calculations are employed for the solid phases and tabulated ionization potential and hydration energy data for aqueous ions. Layered structures, spinel LiMn 2 O 4 , and olivine LiFePO 4 are considered. Protonation is most favorable energetically in layered systems, such as Li 2 MnO 3 and LiCoO 2 . Less favorable are ion-exchange in spinel LiMn 2 O 4 and LiV 3 O 8 . Unfavorable is the substitution of protons for Li in olivine LiFePO 4 , because of the large distortion of the Fe and P coordination polyhedra. The reaction free energy scales roughly linearly with the volume change in the reaction

Energy Sharing and Energy Feedback: Affective and Behavioral Reactions to Communal Energy Displays

Energy Technology Data Exchange (ETDEWEB)

Leygue, Caroline, E-mail: caroline.leygue@nottingham.ac.uk [Horizon Digital Economy Research, University of Nottingham, Nottingham (United Kingdom); Ferguson, Eamonn [School of Psychology, University of Nottingham, Nottingham (United Kingdom); Skatova, Anya [Horizon Digital Economy Research, University of Nottingham, Nottingham (United Kingdom); Spence, Alexa [Horizon Digital Economy Research, University of Nottingham, Nottingham (United Kingdom); School of Psychology, University of Nottingham, Nottingham (United Kingdom)

2014-07-25

Smart meters and energy displays are being rolled out in many countries to help individuals monitor and reduce their energy usage. However, to date, there is little in depth understanding of how they may change behavior. While there is currently a great deal of technical research into developing smart metering, little research has been conducted on how this affects the energy user. This research addresses this gap and explores the user perspective of energy displays when energy is considered as a shared resource. We report an online experiment conducted across the UK examining affective and behavioral responses to energy sharing situations incorporating different types of energy displays. Reactions differed depending on the type of display. In a situation where one person used more than their fair share of energy, displays showing the average amount of usage in the house were associated with feelings of guilt and fear and a decrease in intention to use energy. Displays that identified the person who overused the resource were associated with anger, and direct sanction intentions on those who were overusing energy. Findings are discussed in terms of the smart meter rollout and the potential utility of detailed energy monitoring technologies for behavior change.

Energy sharing and energy feedback: Affective and behavioral reactions to communal energy displays.

Directory of Open Access Journals (Sweden)

Caroline eLeygue

2014-07-01

Full Text Available Smart meters and energy displays are being rolled out in many countries to help individuals monitor and reduce their energy usage. However, to date there is little in depth understanding of how they may change behavior. While there is currently a great deal of technical research into developing smart metering, little research has been conducted on how this affects the energy user. This research addresses this gap and explores the user perspective of energy displays when energy is considered as a shared resource. We report an online experiment conducted across the UK examining affective and behavioral responses to energy sharing situations incorporating different types of energy displays. Reactions differed depending on the type of display. In a situation where one person used more than their fair share of energy, displays showing the average amount of usage in the house were associated with feelings of guilt and fear and a decrease in intention to use energy. Displays that identified the person who overused the resource were associated with anger, and direct sanction intentions on those who were overusing energy. Findings are discussed in terms of the smart meter rollout and the potential utility of detailed energy monitoring technologies for behavior change.

Energy Sharing and Energy Feedback: Affective and Behavioral Reactions to Communal Energy Displays

International Nuclear Information System (INIS)

Leygue, Caroline; Ferguson, Eamonn; Skatova, Anya; Spence, Alexa

2014-01-01

Smart meters and energy displays are being rolled out in many countries to help individuals monitor and reduce their energy usage. However, to date, there is little in depth understanding of how they may change behavior. While there is currently a great deal of technical research into developing smart metering, little research has been conducted on how this affects the energy user. This research addresses this gap and explores the user perspective of energy displays when energy is considered as a shared resource. We report an online experiment conducted across the UK examining affective and behavioral responses to energy sharing situations incorporating different types of energy displays. Reactions differed depending on the type of display. In a situation where one person used more than their fair share of energy, displays showing the average amount of usage in the house were associated with feelings of guilt and fear and a decrease in intention to use energy. Displays that identified the person who overused the resource were associated with anger, and direct sanction intentions on those who were overusing energy. Findings are discussed in terms of the smart meter rollout and the potential utility of detailed energy monitoring technologies for behavior change.

Overview of light water/hydrogen-based low energy nuclear reactions

International Nuclear Information System (INIS)

Miley, George H.; Shrestha, Prajakti J.

2006-01-01

This paper reviews light water and hydrogen-based low-energy nuclear reactions (LENRs) including the different methodologies used to study these reactions and the results obtained. Reports of excess heat production, transmutation reactions, and nuclear radiation emission are cited. An aim of this review is to present a summary of the present status of light water LENR research and provide some insight into where this research is heading. (author)

NMTC/JAM, Simulates High Energy Nuclear Reactions and Nuclear-Meson Transport Processes

International Nuclear Information System (INIS)

Furihata, Shiori

2002-01-01

1 - Description of program or function: NMTC/JAM is an upgraded version of the code system NMTC/JAERI97. NMTC/JAERI97 simulates high energy nuclear reactions and nucleon-meson transport processes. It implements an intra-nuclear cascade model taking account of the in-medium nuclear effects and the pre-equilibrium calculation model based on the exciton one. For treating the nucleon transport process, the nucleon-nucleus cross sections are revised to those derived by the systematics of Pearlstein. Moreover, the level density parameter derived by Ignatyuk is included as a new option for particle evaporation calculation. A geometry package based on the Combinatorial Geometry with multi-array system and the importance sampling technique is implemented in the code. Tally function is also employed for obtaining such physical quantities as neutron energy spectra, heat deposition and nuclide yield without editing a history file. The code can simulate both the primary spallation reaction and the secondary particle transport in the intermediate energy region from 20 MeV to 3.5 GeV by the use of the Monte Carlo technique. The code has been employed in combination with the neutron-photon transport codes available to the energy region below 20 MeV for neutronics calculation of accelerator-based subcritical reactors, analyses of thick target spallation experimented and so on. 2 - Methods: High energy nuclear reactions induced by incident high energy protons, neutrons and pions are simulated with the Monte Carlo Method by the intra-nuclear nucleon-nucleon reaction probabilities based on an intra-nuclear nucleon cascade model followed by the particle evaporation including high energy fission process. Jet-Aa Microscopic transport model (JAM) is employed to simulate high energy nuclear reactions in the energy range of GeV. All reaction channels are taken into account in the JAM calculation. An intra-nuclear cascade model (ISOBAR code) taking account of the in-medium nuclear effects

Back-reactions, short-circuits, leaks and other energy wasteful reactions in biological electron transfer: redox tuning to survive life in O(2).

Science.gov (United States)

Rutherford, A William; Osyczka, Artur; Rappaport, Fabrice

2012-03-09

The energy-converting redox enzymes perform productive reactions efficiently despite the involvement of high energy intermediates in their catalytic cycles. This is achieved by kinetic control: with forward reactions being faster than competing, energy-wasteful reactions. This requires appropriate cofactor spacing, driving forces and reorganizational energies. These features evolved in ancestral enzymes in a low O(2) environment. When O(2) appeared, energy-converting enzymes had to deal with its troublesome chemistry. Various protective mechanisms duly evolved that are not directly related to the enzymes' principal redox roles. These protective mechanisms involve fine-tuning of reduction potentials, switching of pathways and the use of short circuits, back-reactions and side-paths, all of which compromise efficiency. This energetic loss is worth it since it minimises damage from reactive derivatives of O(2) and thus gives the organism a better chance of survival. We examine photosynthetic reaction centres, bc(1) and b(6)f complexes from this view point. In particular, the evolution of the heterodimeric PSI from its homodimeric ancestors is explained as providing a protective back-reaction pathway. This "sacrifice-of-efficiency-for-protection" concept should be generally applicable to bioenergetic enzymes in aerobic environments. Copyright © 2012 Federation of European Biochemical Societies. All rights reserved.

Role of compound nuclei in intermediate-energy heavy-ion reactions

International Nuclear Information System (INIS)

Moretto, L.G.; Wozniak, G.J.

1988-05-01

Hot compound nuclei are frequently produced in intermediate-energy reactions through a variety of processes. Their decay is shown to be an important and at times dominant source of complex fragments, high energy-gamma rays, and even pions

Studying astrophysical reactions with low-energy RI beams at CRIB

Directory of Open Access Journals (Sweden)

Yamaguchi H.

2016-01-01

Full Text Available Studies on nuclear astrophysics, nuclear structure, and other interests have been performed using the radioactive-isotope (RI beams at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS, the University of Tokyo. A typical measurement performed at CRIB is the elastic resonant scattering with the inverse kinematics. One recent experiment was on the α resonant scattering with 7Li and 7Be beams. This study is related to the astrophysical 7Li/7Be(α,γ reactions, important at hot p-p chain and νp-process in supernovae. There have also been measurements based on other experimental methods. The first THM measurement using an RI beam has been performed at CRIB, to study the 18F(p, α15O reaction at astrophysical energies via the three body reaction 2H(18F, α15On. The 18F(p, α 15O reaction rate is crucial to understand the 511-keV γ-ray production in nova explosion phenomena, and we successfully evaluated the reaction cross section at novae temperature and below experimentally for the first time.

Vibrational-state-selected ion--molecule reaction cross sections at thermal energies

NARCIS (Netherlands)

Pijkeren, D. van; Boltjes, E.; Eck, J. van; Niehaus, A.

1984-01-01

A method designed to measure relative ion—molecule reaction rates at thermal collision energies for selected reactant ion vibrational states is described. Relative reaction rates are determined for the three endothermic reactions: H2+ (υ)(He,H)HeH+, H2+ (υ)(Ne,H)NeH+, D2+(υ)(Ne, D)NeD+, and for the

Nuclear reactions video (knowledge base on low energy nuclear physics)

International Nuclear Information System (INIS)

Zagrebaev, V.; Kozhin, A.

1999-01-01

The NRV (nuclear reactions video) is an open and permanently extended global system of management and graphical representation of nuclear data and video-graphic computer simulation of low energy nuclear dynamics. It consists of a complete and renewed nuclear database and well known theoretical models of low energy nuclear reactions altogether forming the 'low energy nuclear knowledge base'. The NRV solves two main problems: 1) fast and visualized obtaining and processing experimental data on nuclear structure and nuclear reactions; 2) possibility for any inexperienced user to analyze experimental data within reliable commonly used models of nuclear dynamics. The system is based on the realization of the following principal things: the net and code compatibility with the main existing nuclear databases; maximal simplicity in handling: extended menu, friendly graphical interface, hypertext description of the models, and so on; maximal visualization of input data, dynamics of studied processes and final results by means of real three-dimensional images, plots, tables and formulas and a three-dimensional animation. All the codes are composed as the real Windows applications and work under Windows 95/NT

Prediction of Tetraoxygen Reaction Mechanism with Sulfur Atom on the Singlet Potential Energy Surface

Directory of Open Access Journals (Sweden)

Ashraf Khademzadeh

2014-01-01

Full Text Available The mechanism of S+O4 (D2h reaction has been investigated at the B3LYP/6-311+G(3df and CCSD levels on the singlet potential energy surface. One stable complex has been found for the S+O4 (D2h reaction, IN1, on the singlet potential energy surface. For the title reaction, we obtained four kinds of products at the B3LYP level, which have enough thermodynamic stability. The results reveal that the product P3 is spontaneous and exothermic with −188.042 and −179.147 kcal/mol in Gibbs free energy and enthalpy of reaction, respectively. Because P1 adduct is produced after passing two low energy level transition states, kinetically, it is the most favorable adduct in the 1S+1O4 (D2h atmospheric reactions.

Ab initio calculation of reaction energies. III. Basis set dependence of relative energies on the FH2 and H2CO potential energy surfaces

International Nuclear Information System (INIS)

Frisch, M.J.; Binkley, J.S.; Schaefer, H.F. III

1984-01-01

The relative energies of the stationary points on the FH 2 and H 2 CO nuclear potential energy surfaces relevant to the hydrogen atom abstraction, H 2 elimination and 1,2-hydrogen shift reactions have been examined using fourth-order Moller--Plesset perturbation theory and a variety of basis sets. The theoretical absolute zero activation energy for the F+H 2 →FH+H reaction is in better agreement with experiment than previous theoretical studies, and part of the disagreement between earlier theoretical calculations and experiment is found to result from the use of assumed rather than calculated zero-point vibrational energies. The fourth-order reaction energy for the elimination of hydrogen from formaldehyde is within 2 kcal mol -1 of the experimental value using the largest basis set considered. The qualitative features of the H 2 CO surface are unchanged by expansion of the basis set beyond the polarized triple-zeta level, but diffuse functions and several sets of polarization functions are found to be necessary for quantitative accuracy in predicted reaction and activation energies. Basis sets and levels of perturbation theory which represent good compromises between computational efficiency and accuracy are recommended

Fragment mass distribution of proton-induced spallation reaction with intermediate energy

International Nuclear Information System (INIS)

Fan Sheng; Ye Yanlin; Xu Chuncheng; Chen Tao; Sobolevsky, N.M.

2000-01-01

The test of part benchmark of SHIELD code is finished. The fragment cross section and mass distribution and excitation function of the residual nuclei from proton-induced spallation reaction on thin Pb target with intermediate energy have been calculated by SHIELD code. And the results are in good agreement with measured data. The fragment mass distribution of the residual nuclei from proton-induced spallation reaction on thick Pb target with incident energy 1.6 GeV have been simulated

Process and device for energy production from thermonuclear fusion reactions

International Nuclear Information System (INIS)

Bussard, R.W.; Coppi, Bruno.

1977-01-01

An energy generating system is described using a fusion reaction. It includes several contrivances for confining a plasma in an area, a protective device around a significant part of each of these confinement contrivances, an appliance for introducing a fusion reaction fuel in each of the confinements so that the plasma may be formed. Each confinement can be separated from the protective device so that it may be replaced by another. The system is connected to the confinements, to the protective devices or to both. It enables the thermal energy to be extracted and transformed into another form, electric, mechanical or both [fr

Isovector couplings for nucleon charge-exchange reactions at intermediate energies

International Nuclear Information System (INIS)

Love, W.G.; Nakayama, K.; Franey, M.A.

1987-01-01

The isovector parts of the effective nucleon-nucleon interaction are studied by examination of the reaction /sup 14/C(p,n) at intermediate energies near zero momentum transfer with use of recently developed G-matrix and free--t-matrix interactions. The spin-independent coupling (V/sub tau/) exhibits a strong energy and density dependence which, in the case of the G matrix based on the Bonn potential, significantly improves the agreement between calculated values of chemical bondV/sub σ//sub tau//V/sub tau/chemical bond 2 at q = 0 and those recently extracted from the reaction /sup 14/C

(γ,2n) reactions in complexe nuclei at intermediate energies

International Nuclear Information System (INIS)

Pinheiro Filho, J. de D.

1976-01-01

The Monte Carlo Method has been used in the intranuclear cascade model for the calculation of the cross sections of the (γ,2n) reactions in complex nuclei 9 Be, 12 C, 16 O, 59 Co, 103 Rh, 127 I, 197 Au and 209 Bi at intermediate energies (200MeV-1000MeV). The initial photon-interaction via the photomesonic and quasi-deuteron mechanisms have been taken into account. The nuclear model used was a degenerate Fermi gas of nucleons, and the Pauli exclusion principle was considered in all secondary interactions. To improve accuracy in the results of the calculations, 30000 cascades have been followed for each target nucleus at a given incident photon energy. The probabilities of the various (γ,2n) reactions, as well as the correspondent cross section obtained, are summarized in tables and graphs. New data on the cross sections of the 59 Co (γ,2n) and 209 Bi (γ,2n) reactions at photon energies between 300 MeV and 1000MeV are also reported. These measurements were obtained with the Bremsstrahlung beams of the Frascati 1 GeV Electron Synchrotron. A comparison between all existing data in the literature on the (γ,2n) reaction cross sections and the estimates by the Monte Carlo Method, is presented. (Author) [pt

dd →3 Hen Reaction at Intermediate Energies

International Nuclear Information System (INIS)

Ladygina, N. B.

2012-01-01

The dd → 3 Hen reaction is considered at the energies between 200 and 520 MeV. The Alt-Grassberger-Sandhas equations are iterated up to the lowest order terms over the nucleon-nucleon t-matrix. The parameterized 3He wave function including five components is used. The angular dependence of the differential cross section and energy dependence of tensor analyzing power T 20 at the zero scattering angle are presented in comparison with the experimental data. (author)

High-energy nuclear reaction mechanisms - fission, fragmentation and spallation

International Nuclear Information System (INIS)

Kaufman, S.B.

1987-01-01

Measurements of the correlations in kinetic energy, mass, charge, and angle of coincident fragments formed in high-energy nuclear reactions have helped to characterize the processes of fission, fragmentation and spallation. For example, fission or fission-like two-body breakup mechanisms result in a strong angular correlation between two heavy fragments; in addition, the momentum transfer in the reaction can be deduced from the correlation. Another example is the multiplicity of light charged particles associated with a given heavy fragment, which is a measure of the violence of the collision, thus distinguishing between central and peripheral collisions. A summary of what has been learned about these processes from such studies will be given, along with some suggestions for further experiments

Communication: State-to-state dynamics of the Cl + H2O → HCl + OH reaction: Energy flow into reaction coordinate and transition-state control of product energy disposal.

Science.gov (United States)

Zhao, Bin; Sun, Zhigang; Guo, Hua

2015-06-28

Quantum state-to-state dynamics of a prototypical four-atom reaction, namely, Cl + H2O → HCl + OH, is investigated for the first time in full dimensionality using a transition-state wave packet method. The state-to-state reactivity and its dependence on the reactant internal excitations are analyzed and found to share many similarities both energetically and dynamically with the H + H2O → H2 + OH reaction. The strong enhancement of reactivity by the H2O stretching vibrational excitations in both reactions is attributed to the favorable energy flow into the reaction coordinate near the transition state. On the other hand, the insensitivity of the product state distributions with regard to reactant internal excitation stems apparently from the transition-state control of product energy disposal.

Communication: State-to-state dynamics of the Cl + H2O → HCl + OH reaction: Energy flow into reaction coordinate and transition-state control of product energy disposal

International Nuclear Information System (INIS)

Zhao, Bin; Guo, Hua; Sun, Zhigang

2015-01-01

Quantum state-to-state dynamics of a prototypical four-atom reaction, namely, Cl + H 2 O → HCl + OH, is investigated for the first time in full dimensionality using a transition-state wave packet method. The state-to-state reactivity and its dependence on the reactant internal excitations are analyzed and found to share many similarities both energetically and dynamically with the H + H 2 O → H 2 + OH reaction. The strong enhancement of reactivity by the H 2 O stretching vibrational excitations in both reactions is attributed to the favorable energy flow into the reaction coordinate near the transition state. On the other hand, the insensitivity of the product state distributions with regard to reactant internal excitation stems apparently from the transition-state control of product energy disposal

Intermediate and high energy nuclear reactions at the hadronic structural level

Energy Technology Data Exchange (ETDEWEB)

Slowinski, B [Institute of Physics, Warsaw, University of Technology, Poland, Institute of Atomic Energy, Swierk, (Poland)

1997-12-31

Form tens of MeV to several hundred of GeV is stretched out quite a large interval of energy when the interaction between hadrons (for instance, pion/nucleon-nucleus and nucleus-nucleus reactions) can be described by the considerably simplified way with still acceptable accuracy. This happens because in this energy region hadrons (i.e. pions, nucleons etc.) remain quasiparticles of nuclear matter mostly without revealing any internal structure, their de Broglie`s wavelength is much shorter as compared to the average intranuclear nucleon`s distance, and the energy transfers in the reaction are, on the average, significantly greater than the binding energy of nucleons inside nuclei. Consequently an approach to the analysis of these phenomena based on simple geometric and probabilistic considerations is justifiable, especially for many practical purposes, in particular, for shielding and dosimetric estimations, material behaviour prediction, as well as for the approximate evaluation of electronuclear breeding effects in different composites of target materials, for nuclear passivation problems and so on. In this work basic physical reasons of such a simplified picture of intermediate and high energy nuclear reactions are presented. The most usual phenomenological models of hadronic multiple emission/production and recent results of the cascade evaporation type models, are also discussed. 2 figs.

Effect of free-particle collisions in high energy proton and pion-induced nuclear reactions

International Nuclear Information System (INIS)

Jacob, N.P. Jr.

1975-07-01

The effect of free-particle collisions in simple ''knockout'' reactions of the form (a,aN) and in more complex nuclear reactions of the form (a,X) was investigated by using protons and pions. Cross sections for the 48 Ti(p,2p) 47 Sc and the 74 Ge(p,2p) 73 Ga reactions were measured from 0.3 to 4.6 GeV incident energy. The results indicate a rise in (p,2p) cross section for each reaction of about (25 +- 3) percent between the energies 0.3 and 1.0 GeV, and are correlated to a large increase in the total free-particle pp scattering cross sections over the same energy region. Results are compared to previous (p,2p) excitation functions in the GeV energy region and to (p,2p) cross section calculations based on a Monte Carlo intranuclear cascade-evaporation model. Cross section measurements for (π/sup +-/, πN) and other more complex pion-induced spallation reactions were measured for the light target nuclei 14 N, 16 O, and 19 F from 45 to 550 MeV incident pion energy. These measurements indicate a broad peak in the excitation functions for both (π,πN) and (π,X) reactions near 180 MeV incident energy. This corresponds to the large resonances observed in the free-particle π + p and π - p cross sections at the same energy. Striking differences in (π,πN) cross section magnitudes are observed among the light nuclei targets. The experimental cross section ratio sigma(π - ,π - n)/sigma(π + ,πN) at 180 MeV is 1.7 +- 0.2 for all three targets. The experimental results are compared to previous pion and analogous proton-induced reactions, to Monte Carlo intranuclear cascade-evaporation calculations, and to a semi-classical nucleon charge exchange model. (108 references) (auth)

Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

Energy Technology Data Exchange (ETDEWEB)

Rojas-Chavez, H., E-mail: uu_gg_oo@yahoo.com.mx [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico) and Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo (Mexico); Reyes-Carmona, F. [Facultad de Quimica - UNAM, Circuito de la Investigacion Cientifica s/n, C.U. Del. Coyoacan (Mexico); Jaramillo-Vigueras, D. [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico)

2011-10-15

Highlights: {yields} PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. {yields} During high-energy milling oxygen has to be chemically reduced from the lead oxide. {yields} Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

International Nuclear Information System (INIS)

Rojas-Chavez, H.; Reyes-Carmona, F.; Jaramillo-Vigueras, D.

2011-01-01

Highlights: → PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. → During high-energy milling oxygen has to be chemically reduced from the lead oxide. → Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

Pre-equilibrium emission of nucleons from reactions induced by medium-energy heavy ions

International Nuclear Information System (INIS)

Korolija, M.; Holuh, E.; Cindro, N.; Hilscher, D.

1984-01-01

Recent data on fast-nucleon emission in heavy-ion-induced reactions are analysed successfully in terms of pre-equilibrium models; it is shown that the relevant parameters of those models preserve the physical meaning they have in light-ion-induced reactions. The initial exciton number obtained from a Griffin-plot analysis and the initial number of degrees of freedom, which is the relevant parameter of the modified HMB model, appear to be approximately equal for a given reaction at a given energy. It is inferred that, for heavy-ion reactions, the determination of such a parameter is substantially dominated by the centre-of-mass energy per nucleon above the Coulomb barrier, in contrast with the results of nucleon-induced reactions

Analysis of the proton-induced reactions at 150 MeV - 24 GeV by high energy nuclear reaction code JAM

International Nuclear Information System (INIS)

Niita, Koji; Nara, Yasushi; Takada, Hiroshi; Nakashima, Hiroshi; Chiba, Satoshi; Ikeda, Yujiro

1999-09-01

We are developing a nucleon-meson transport code NMTC/JAM, which is an upgraded version of NMTC/JAERI. NMTC/JAM implements the high energy nuclear reaction code JAM for the infra-nuclear cascade part. By using JAM, the upper limits of the incident energies in NMTC/JAERI, 3.5 GeV for nucleons and 2.5 GeV for mesons, are increased drastically up to several hundreds GeV. We have modified the original JAM code in order to estimate the residual nucleus and its excitation energy for nucleon or pion induced reactions by assuming a simple model for target nucleus. As a result, we have succeeded in lowering the applicable energies of JAM down to about 150 MeV. In this report, we describe the main components of JAM code, which should be implemented in NMTC/JAM, and compare the results calculated by JAM code with the experimental data and with those by LAHET2.7 code for proton induced reactions from 150 MeV to several 10 GeV. It has been found that the results of JAM can reproduce quite well the experimental double differential cross sections of neutrons and pions emitted from the proton induced reactions from 150 MeV to several 10 GeV. On the other hand, the results of LAHET2.7 show the strange behavior of the angular distribution of nucleons and pions from the reactions above 4 GeV. (author)

The (3He,t) and (d,2He)reactions at intermediate energies

International Nuclear Information System (INIS)

Brockstedt, A.

1987-09-01

The ( 3 He,t) reaction has been studied at 0.6-2.3 GeV at small scattering angles, 0-7 degrees, on various nuclei ( 12 C, 13 C, 26 Mg, 40 Ca, 48 Ca, 54 Fe, 90 Zr, 159 Tb, 208 Pb) including a proton target. The reaction is a single-step reaction and selects the spin-isospin channel. Angular distributions for low-lying states in 12 N are well described by DWIA calculations. From 13 C to 13 N transitions the ratio J στ /J τ , at momentum transfer, q, close to zero, is derived. The ratio remains roughly constant in the region 300 - 700 MeV/nucleon. The position of the quasi-free peak is shifted compared with free nucleon-nucleon scattering. The shift is towards higher excitation energies at q approx 1.4 fm -1 , and towards lower excitation energies at q approx 2.5 fm -1 . The p( 3 He,t)Δ ++ reaction is analysed as one-pion exchange and the ( 3 He,t) form factor is extracted. The shape and position of the Δ resonance seem to be independent of target mass for the targets studied. Compared with the p to Δ ++ transition the position is shifted towards lower excitation energy in nuclei. The (d,2p[ 1 S 0 ]) reaction, with the two protons in an 1 S 0 state labelled 2 He, is studied at 0.65 and 2.0 GeV at small angles, 0-4 degrees, on some of the targets used in the ( 3 He,t) experiment (p, 12 C, 40 Ca, 54 Fe). This reaction is also a one-step reaction that can be used for studies of spin-isospin excitations. Cross sections and tensor analysing powers are determined for the p(d, 2 He)n reaction. These results are compared with PWIA calculations. The Δ resonance in carbon is also here shifted down in excitation energy compared with the proton target. (author)

Effects of reagent translational and vibrational energy on the dynamics of endothermic reactions

Energy Technology Data Exchange (ETDEWEB)

Krajnovich, D.; Zhang, Z.; Huisken, F.; Shen, Y.R.; Lee, Y.T.

1981-07-01

The endothermic reactions Br + CH/sub 3/I ..-->.. CH/sub 3/ + IBr (..delta..H/sub 0//sup 0/ = 13 kcal/mole) and Br + CF/sub 3/I ..-->.. CF/sub 3/ + IBr (..delta..H/sub 0//sup 0/ = 11 kcal/mole) have been studied by the crossed molecular beams method. Detailed center-of-mass contour maps of the IBr product flux as a function of recoil velocity and scattering angle are derived. For both systems it is found that the IBr product is sharply backward scattered with respect to the incident Br dirction, and that most of the available energy goes into product translation. Vibrational enhancement of the Br + CF/sub 3/I reaction was investigated by using the infrared multiphoton absorption process to prepare highly vibrationally excited CF/sub 3/I. At a collision energy of 31 kcal/mole (several times the barrier height), reagent vibrational energy appears to be less effective than an equivalent amount of (additional) translational energy in promoting reaction. More forward scattered IBr is produced in reactions of Br with vibrationally hot CF/sub 3/I.

Effects of reagent translational and vibrational energy on the dynamics of endothermic reactions

International Nuclear Information System (INIS)

Krajnovich, D.; Zhang, Z.; Huisken, F.; Shen, Y.R.; Lee, Y.T.

1981-07-01

The endothermic reactions Br + CH 3 I → CH 3 + IBr (ΔH 0 0 = 13 kcal/mole) and Br + CF 3 I → CF 3 + IBr (ΔH 0 0 = 11 kcal/mole) have been studied by the crossed molecular beams method. Detailed center-of-mass contour maps of the IBr product flux as a function of recoil velocity and scattering angle are derived. For both systems it is found that the IBr product is sharply backward scattered with respect to the incident Br dirction, and that most of the available energy goes into product translation. Vibrational enhancement of the Br + CF 3 I reaction was investigated by using the infrared multiphoton absorption process to prepare highly vibrationally excited CF 3 I. At a collision energy of 31 kcal/mole (several times the barrier height), reagent vibrational energy appears to be less effective than an equivalent amount of (additional) translational energy in promoting reaction. More forward scattered IBr is produced in reactions of Br with vibrationally hot CF 3 I

A new type of power energy for accelerating chemical reactions: the nature of a microwave-driving force for accelerating chemical reactions.

Science.gov (United States)

Zhou, Jicheng; Xu, Wentao; You, Zhimin; Wang, Zhe; Luo, Yushang; Gao, Lingfei; Yin, Cheng; Peng, Renjie; Lan, Lixin

2016-04-27

The use of microwave (MW) irradiation to increase the rate of chemical reactions has attracted much attention recently in nearly all fields of chemistry due to substantial enhancements in reaction rates. However, the intrinsic nature of the effects of MW irradiation on chemical reactions remains unclear. Herein, the highly effective conversion of NO and decomposition of H2S via MW catalysis were investigated. The temperature was decreased by several hundred degrees centigrade. Moreover, the apparent activation energy (Ea') decreased substantially under MW irradiation. Importantly, for the first time, a model of the interactions between microwave electromagnetic waves and molecules is proposed to elucidate the intrinsic reason for the reduction in the Ea' under MW irradiation, and a formula for the quantitative estimation of the decrease in the Ea' was determined. MW irradiation energy was partially transformed to reduce the Ea', and MW irradiation is a new type of power energy for speeding up chemical reactions. The effect of MW irradiation on chemical reactions was determined. Our findings challenge both the classical view of MW irradiation as only a heating method and the controversial MW non-thermal effect and open a promising avenue for the development of novel MW catalytic reaction technology.

Probing the nuclear symmetry energy at high densities with nuclear reactions

Science.gov (United States)

Leifels, Y.

2017-11-01

The nuclear equation of state is a topic of highest current interest in nuclear structure and reactions as well as in astrophysics. The symmetry energy is the part of the equation of state which is connected to the asymmetry in the neutron/proton content. During recent years a multitude of experimental and theoretical efforts on different fields have been undertaken to constraint its density dependence at low densities but also above saturation density (ρ_0=0.16 fm ^{-3} . Conventionally the symmetry energy is described by its magnitude S_v and the slope parameter L , both at saturation density. Values of L = 44 -66MeV and S_v=31 -33MeV have been deduced in recent compilations of nuclear structure, heavy-ion reaction and astrophysics data. Apart from astrophysical data on mass and radii of neutron stars, heavy-ion reactions at incident energies of several 100MeV are the only means do access the high density behaviour of the symmetry energy. In particular, meson production and collective flows upto about 1 AGeV are predicted to be sensitive to the slope of the symmetry energy as a function of density. From the measurement of elliptic flow of neutrons with respect to charged particles at GSI, a more stringent constraint for the slope of the symmetry energy at supra-saturation densities has been deduced. Future options to reach even higher densities will be discussed.

Reaction mechanism and nuclear correlations study by low energy pion double charge exchange

International Nuclear Information System (INIS)

Weinfeld, Z.

1993-06-01

In pion double-charge-exchange (DCX) reactions, a positive (negative) pion is incident on a nucleus and a negative (positive) pion emerges. These reactions are of fundamental interest since the process must involve at least two nucleons in order to conserve charge. Although two nucleon processes are present in many reactions they are usually masked by the dominant single nucleon processes. DCX is unique in that respect since it is a two nucleon process in lowest order and thus may be sensitive to two-nucleon correlations. Measurements of low energy pion double-charge-exchange reactions to the double-isobaric-analog-state (DIAS) and ground-state (GS) of the residual nucleus provide new means for studying nucleon-nucleon correlations in nuclei. At low energies (T π 7/2 shell at energies ranging from 25 to 65 MeV. Cross sections were measured on 42,44,48 Ca, 46,50 Ti and 54 Fe. The calcium isotopes make a good set of nuclei on which to study the effects of correlations in DCX reactions

New Mechanism of Low Energy Nuclear Reactions Using Superlow

Science.gov (United States)

Gareev, F. A.; Zhidkova, I. E.

2006-03-01

We proposed a new mechanism of LENR (low energy nuclear reactions) cooperative processes in the whole system - nuclei+atoms+condensed matter can occur at smaller threshold than the corresponding ones assoiciated with free constituents. The cooperative processes can be induced and enhanced by (``superlow energy'') external fields. The excess heat is the emission of internal energy, and transmutations from LENR are the result of redistribution of the internal energy of the whole system. A review of possible stimulation mechanisms of LENR is presented. We have concluded that transmutation of nuclei at low energies and excess heat are possible in the framework of the known fundamental physical laws: The universal resonance synchronization principle, and based on it, different enhancement mechanisms of reaction rates are responsible for these processes. The excitation and ionization of atoms may play the role of a trigger for LENR. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0511092 v1 30 Nov 2005. F.A. Gareev, In: FPB-98, Novosibirsk, June 1998, p.92; F.A.Gareev, G.F. Gareeva, in: Novosibirsk, July 2000, p.161. F.A. Gareev, I.E. Zhidkova and Yu.L. Ratis, Preprint JINR P4-2004-68, Dubna, 2004. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0505021 9 May 2005.

Consistent post-reaction vibrational energy redistribution in DSMC simulations using TCE model

Science.gov (United States)

Borges Sebastião, Israel; Alexeenko, Alina

2016-10-01

The direct simulation Monte Carlo (DSMC) method has been widely applied to study shockwaves, hypersonic reentry flows, and other nonequilibrium flow phenomena. Although there is currently active research on high-fidelity models based on ab initio data, the total collision energy (TCE) and Larsen-Borgnakke (LB) models remain the most often used chemistry and relaxation models in DSMC simulations, respectively. The conventional implementation of the discrete LB model, however, may not satisfy detailed balance when recombination and exchange reactions play an important role in the flow energy balance. This issue can become even more critical in reacting mixtures involving polyatomic molecules, such as in combustion. In this work, this important shortcoming is addressed and an empirical approach to consistently specify the post-reaction vibrational states close to thermochemical equilibrium conditions is proposed within the TCE framework. Following Bird's quantum-kinetic (QK) methodology for populating post-reaction states, the new TCE-based approach involves two main steps. The state-specific TCE reaction probabilities for a forward reaction are first pre-computed from equilibrium 0-D simulations. These probabilities are then employed to populate the post-reaction vibrational states of the corresponding reverse reaction. The new approach is illustrated by application to exchange and recombination reactions relevant to H2-O2 combustion processes.

Definition and determination of the triplet-triplet energy transfer reaction coordinate.

Science.gov (United States)

Zapata, Felipe; Marazzi, Marco; Castaño, Obis; Acuña, A Ulises; Frutos, Luis Manuel

2014-01-21

A definition of the triplet-triplet energy transfer reaction coordinate within the very weak electronic coupling limit is proposed, and a novel theoretical formalism is developed for its quantitative determination in terms of internal coordinates The present formalism permits (i) the separation of donor and acceptor contributions to the reaction coordinate, (ii) the identification of the intrinsic role of donor and acceptor in the triplet energy transfer process, and (iii) the quantification of the effect of every internal coordinate on the transfer process. This formalism is general and can be applied to classical as well as to nonvertical triplet energy transfer processes. The utility of the novel formalism is demonstrated here by its application to the paradigm of nonvertical triplet-triplet energy transfer involving cis-stilbene as acceptor molecule. In this way the effect of each internal molecular coordinate in promoting the transfer rate, from triplet donors in the low and high-energy limit, could be analyzed in detail.

Theoretical calculation of n + {sup 59}Co reaction in energy region up to 100 MeV

Energy Technology Data Exchange (ETDEWEB)

Qingbiao, Shen; Baosheng, Yu; Dunjiu, Cai [Chinese Nuclear Data Center, Beijing, BJ (China)

1996-06-01

A set of neutron optical potential parameters for {sup 59}Co in energy region of 2{approx}100 MeV was obtained based on concerned experimental data. Various cross sections of n + {sup 59}Co reactions were calculated and predicted. The calculated results show that the activation products {sup 58,57}Co, {sup 59}Fe and {sup 56}Mn are main neutron monitor reaction products for n + {sup 59}Co reaction in energy range up to 100 MeV. {sup 54}Mn production reaction can be a promising neutron monitor reaction in the energy region from 30 to 100 MeV. (6 figs.).

Effect of compound nuclear reaction mechanism in 12C(6Li,d) reaction at sub-Coulomb energy

Science.gov (United States)

Mondal, Ashok; Adhikari, S.; Basu, C.

2017-09-01

The angular distribution of the 12C(6Li,d) reaction populating the 6.92 and 7.12 MeV states of 16O at sub-Coulomb energy (Ecm=3 MeV) are analysed in the framework of the Distorted Wave Born Approximation (DWBA). Recent results on excitation function measurements and backward angle angular distributions derive ANC for both the states on the basis of an alpha transfer mechanism. In the present work, we show that considering both forward and backward angle data in the analysis, the 7.12 MeV state at sub-Coulomb energy is populated from Compound nuclear process rather than transfer process. The 6.92 MeV state is however produced from direct reaction mechanism.

Probing nuclei with high-energy hadronic reactions

International Nuclear Information System (INIS)

Moss, J.M.

1995-01-01

I review the subject of hadron-nucleus collisions at energies where peturbative theory is applicable. Reactions studied experimentally at the Fermilab Tevatron and CERN's Super Proton Synchrotron include the Drell-Yan Process, direct photon production, quarkonium production, and open charm production. I conclude with an observation about a new era of proton-nucleus and nucleus-nucleus experiments which will be carried out at the hadron colliders, RHIC and LHC

Collisions of polyatomic ions with surfaces: incident energy partitioning and chemical reactions

International Nuclear Information System (INIS)

Zabka, J.; Roithova, J.; Dolejsek, Z.; Herman, Z.

2002-01-01

Collision of polyatomic ions with surfaces were investigated in ion-surface scattering experiments to obtain more information on energy partitioning in ion-surface collision and on chemical reactions at surfaces. Mass spectra, translation energy and angular distributions of product ions were measured in dependence on the incident energy and the incident angle of polyatomic projectiles. From these data distributions of energy fractions resulting in internal excitation of the projectile, translation energy of the product ions, and energy absorbed by the surface were determined. The surface investigated were a standard stainless steel surface, covered by hydrocarbons, carbon surfaces at room and elevated temperatures, and several surfaces covered by a self-assembled monolayers (C 12 -hydrocarbon SAM, C 11 -perfluorohydrocarbon SAM, and C 11 hydrocarbon with terminal -COOH group SAM). The main processes observed at collision energies of 10 - 50 eV were: neutralization of the ions at surfaces, inelastic scattering and dissociations of the projectile ions, quasi elastic scattering of the projectile ions, and chemical reactions with the surface material (usually hydrogen-atom transfer reactions). The ion survival factor was estimated to be a few percent for even-electron ions (like protonated ethanol ion, C 2 H 5 O + , CD 5 + ) and about 10 - 10 2 times lower for radical ions (like ethanol and benzene molecular ions, CD 4 + ). In the polyatomic ion -surface energy transfer experiments, the ethanol molecular ion was used as a well-characterized projectile ion. The results with most of the surfaces studied showed in the collision energy range of 13 - 32 eV that most collisions were strongly inelastic with about 6 - 8 % of the incident projectile energy transformed into internal excitation of the projectile (independent of the incident angle) and led partially to its further dissociation in a unimolecular way after the interaction with the surface. The incident energy

Recoil properties of radionuclides formed in photospallation reactions on complex nuclei at intermediate energies

International Nuclear Information System (INIS)

Haba, Hiromitsu; Oura, Yasuji; Shibata, Seiichi; Furukawa, Michiaki; Fujiwara, Ichiro

2001-01-01

A short review is given on our studies of recoil properties of radionuclides formed in photospallation reactions induced by bremsstrahlung of end-point energies (E 0 ) from 600 to 1100 MeV, in which the thick-target thick-catcher method was employed. The measurements have been successful on 14, 24, 26, 31, 21 and 20 nuclides from nat V, nat Cu, 93 Nb, nat Ag, nat Ta, and 197 Au, respectively. Reflecting the resonance character in a photonuclear reaction, the mean ranges FW and BW in the forward and backward directions, respectively, are E 0 -independent at the studied energies and classified into two groups accounting for the (γ, xn) (x ≥ 1) and (γ, xnyp) (x, y ≥ 1) processes. The forward-to-backward ratios (F/B) are independent of the mass difference (ΔA) between a product (A p ) and a target (A t ) and also of A t . The kinematic properties of the product nuclei were analyzed by the two-step vector velocity model. The forward velocity ν after the first step of photon-reaction is quite different from that of proton-reaction at proton energies of E p ≤ 3 GeV, though the difference disappears at higher energies. On the other hand, the mean kinetic energy T of the residual nucleus in the second step is almost equal to that of proton-reaction irrespective of E p . A comparison with T values calculated by the PICA (Photon-Induced Intranuclear Cascade Analysis) code at E 0 =400 MeV was also performed. It was found that although the code well reproduces the experimental results of nat V and nat Cu, the same calculation for heavier targets gives T values lower than the experimental results, indicating some nuclear-structure effect, such as a medium effect notably at A t ≥ 100. An average kinetic energy carried off by the emitted particles ε s =T/(ΔA/A t ) of both photon- and proton-reactions seem to increase with an increase of A t up to around A t =100, and become almost constant at larger A t , implying some change in the nuclear structure effect in this

6,7Li + 28Si total reaction cross sections at near barrier energies

International Nuclear Information System (INIS)

Pakou, A.; Musumarra, A.; Pierroutsakou, D.; Alamanos, N.; Assimakopoulos, P.A.; Divis, N.; Doukelis, G.; Gillibert, A.; Harissopulos, S.; Kalyva, G.; Kokkoris, M.; Lagoyannis, A.; Mertzimekis, T.J.; Nicolis, N.G.; Papachristodoulou, C.; Perdikakis, G.; Roubos, D.; Rusek, K.; Spyrou, S.; Zarkadas, Ch.

2007-01-01

Total reaction cross section measurements for the 6,7 Li + 28 Si systems have been performed at near-barrier energies. The results indicate that, with respect to the potential anomaly at barrier, 6 Li and 7 Li on light targets exhibit similar energy dependence on the imaginary potential. Comparisons are made with 6,7 Li cross sections on light and heavy targets, extracted via previous elastic scattering measurements and also with CDCC calculations. Energy dependent parametrisations are also obtained for total reaction cross sections of 6,7 Li on Si, as well as on any target, at near barrier energies

Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

International Nuclear Information System (INIS)

Osborn, David L.

2017-01-01

Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low temperature combustion and the oxidation of volatile organic compounds in earth’s atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization make characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, while master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

Science.gov (United States)

Osborn, David L.

2017-05-01

Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low-temperature combustion and in the oxidation of volatile organic compounds in Earth's atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization makes characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, and master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

Alpha-particle energy spectra measured at forward angles in heavy-ion-induced reactions

International Nuclear Information System (INIS)

Borcea, C.; Cierlic, E.; Kalpakchieva, R.; Oganessian, Yu.Ts.; Penionzhkevich, Yu.E.

1980-01-01

Energy spectra have been measured for α-particles emitted in the bombardment of 159 Tb, 181 Ta, 197 Au, and 232 Th nuclei by 20 Ne, 22 Ne, and 40 Ar projectiles. The reaction products emitted in the angular range (0+-2)deg relative to the beam direction were analyzed using a magnetic spectrometer and detected by means of a semiconductor ΔE-E telescope. It was found that in all cases the experimentally measured maximum α-particle energy almost amounts to the maximum possible value calculated from the reaction energy balance for a two-body exit channel. A correlation was found between the measured absolute cross section in different target-projectile combinations and the α-particle binding energy in the target nuclei. On the basis of the obtained results a conclusion has been drawn that the α-particles are emitted in the early stage of the reaction

Use of a GDMS for high-energy reaction data

International Nuclear Information System (INIS)

Moorhead, W.G.

1978-01-01

At CERN, data on high-energy reactions is being compiled using a Generalized Data Management System. The GDMS is a stand-alone system designed for administrative and engineering applications. The Data Base at present contains about 20,000 cross-section values, each linked to a description of the corresponding reaction, and the publication from which the value was derived. The immediate objective is to produce the widely circulated Compilation Reports, and the standard Report Generator of the GDMS is being used for this. Direct retrieval is also possible

Observation of the one- to six-neutron transfer reactions at sub-barrier energies

Energy Technology Data Exchange (ETDEWEB)

Jiang, C.L.; Rehm, K.E.; Gehring, J. [and others

1995-08-01

It was suggested many years ago that when two heavy nuclei are in contact during a grazing collision, the transfer of several correlated neutron-pairs could occur. Despite considerable experimental effort, however, so far only cross sections for up to four-neutron transfers have been uniquely identified. The main difficulties in the study of multi-neutron transfer reactions are the small cross sections encountered at incident energies close to the barrier, and various experimental uncertainties which can complicate the analysis of these reactions. We have for the first time found evidence for multi-neutron transfer reactions covering the full sequence from one- to six-neutron transfer reactions at sub-barrier energies in the system {sup 58}Ni + {sup 100}Mo.

Photon Energy Threshold in Direct Photocatalysis with Metal Nanoparticles: Key Evidence from the Action Spectrum of the Reaction.

Science.gov (United States)

Sarina, Sarina; Jaatinen, Esa; Xiao, Qi; Huang, Yi Ming; Christopher, Philip; Zhao, Jin Cai; Zhu, Huai Yong

2017-06-01

By investigating the action spectra (the relationship between the irradiation wavelength and apparent quantum efficiency of reactions under constant irradiance) of a number of reactions catalyzed by nanoparticles including plasmonic metals, nonplasmonic metals, and their alloys at near-ambient temperatures, we found that a photon energy threshold exists in each photocatalytic reaction; only photons with sufficient energy (e.g., higher than the energy level of the lowest unoccupied molecular orbitals) can initiate the reactions. This energy alignment (and the photon energy threshold) is determined by various factors, including the wavelength and intensity of irradiation, molecule structure, reaction temperature, and so forth. Hence, distinct action spectra were observed in the same type of reaction catalyzed by the same catalyst due to a different substituent group, a slightly changed reaction temperature. These results indicate that photon-electron excitations, instead of the photothermal effect, play a dominant role in direct photocatalysis of metal nanoparticles for many reactions.

Fusion reaction using low energy neutron-excess nucleus beam

International Nuclear Information System (INIS)

Fukuda, Tomokazu

1994-01-01

The present state and the plan of the experiment of measuring the fusion reaction near barriers by using neutron-excess nucleus beam, which has been advanced at RIKEN are reported. One of the purposes of this experiment is the feasibility investigation of the fusion reaction by using neutron-excess nuclei, which is indispensable for synthesizing superheavy elements. It is intended to systematically explore some enhancing mechanism in the neutron-excess nuclei which are unfavorable in beam intensity. This research can become the good means to prove the dynamic behavior of the neutrons on the surfaces of nuclei in reaction. The fusion reaction of 27 Al + Au was measured by using the stable nucleus beam of 27 Al, and the results are shown. In order to know the low energy fusion reaction of 11 Li and 11 Be which are typical halo nuclei, the identification by characteristic α ray of composite nuclei is carried out in 7,9,11 Li + 209 Bi and 9,10,11 Be + 208 Pb. A new detector having high performance, New MUSIC, is being developed. As the experiment by using this detector, the efficient measurement of the fusion reaction by using heavy neutron-excess nuclei up to Ni is considered. An example of 8 Li + α → 11 B + n reaction for celestial body physics is mentioned. (K.I.)

Photonucleon reactions in 40Ca at intermediate energies

International Nuclear Information System (INIS)

Adler, J.-O.; Bulow, B.; Jonsson, G.G.; Lindgren, K.

1976-01-01

The yields of the reactions 40 Ca(γ,n) 39 Ca* and 40 Ca(γ,p) 39 K* to the first three excited states have been measured for bremsstrahlung with end-point energies in the region 100-750 MeV. The C 2 S values for the first excited state were deduced from the pion photoproduction contribution to the measured yields. (Auth.)

A primer for electroweak induced low-energy nuclear reactions

Indian Academy of Sciences (India)

paper is devoted to delineating the unifying features and to an overall synthesis of .... reaction e− + p → n + νe for electrons and protons of very low kinetic energy ..... of Z protons and N = (A − Z) neutrons where A is the total number of nucleons.

Experimental Study of Photon Induced Reactions on 3He and 4He at Low Energies

International Nuclear Information System (INIS)

Tornow, W.

2011-01-01

Data are reported for the photodisintegration cross section of the reaction 3 He(γ, p) 2 H at ten energies between 7.0 and 16.0 MeV. Very preliminary data are presented for the reaction 4 He(γ, p) 3 H between 22.0 and 29.5 MeV in 0.5 MeV energy steps, and for the reaction 4 He(γ, n) 3 He at three energies around 28.0 MeV. High-pressure He/Xe gas scintillators served as target and detector. Our data are in better agreement with recent theoretical calculations than the majority of the existing data for all three reactions, but differ significantly from recent data taken with a mono-energetic photon beam and a time-projection chamber. (author)

Central collisions in intermediate energy heavy-ion reactions

International Nuclear Information System (INIS)

Wong, C.Y.

1979-01-01

The critical collisions in intermediate energy heavy-ion reactions are examined from both a microscopic and macroscopic viewpoint. In the microscopic description the proper tool is the extended TDHF approximation involving both the mean field and the particle collisions. To understand the underlying physics, the effect of the mean field and the effect of particle collisions are studied separately. It is found that th sudden increase in the density of the overlapping region can cause the volcano effect, leading to the complete disintegration of one of the nuclei. The self-consistent mean field also gives rise to the bunching instability when the two Fermi spheres of the colliding nucleons separate. The collision between nucleons, on the other hand, leads to irreversible dissipation, thermalization, and the possibility of a hydrodynamical description of the dynamics. Next is studied the dynamics of central collisions using the hydrodynamical description for many combinations of targets and projectiles at different energies. The formation of shock waves, sidesplash, and the complete disintegration of the whole nucleus are examined. Nuclear viscosity is found to affect the angular distribution of the reaction products and also the maximum compression ratio achieved during the collision. 28 references

Emission of high-energy charged particles at 00 in Ne-induced reactions

International Nuclear Information System (INIS)

Borcea, C.; Gierlik, E.; Kalinin, A.M.; Kalpakchieva, R.; Oganessia, Yu.Ts.; Pawlat, T.; Penionzhkevich, Yu.E.; Ryakhlyuk, A.V.

1982-01-01

Inclusive energy spectra have been measured for light charged particles emitted in the bombardment of 232 Th, 181 Ta, sup(nat)Ti and 12 C targets by 22 Ne ions at 178 MeV and sup(nat)Ti target by 20 Ne ions at 196 MeV. The reaction products were analysed and detected by means of a ΔE-E telescope placed in the focal plane of a magnetic spectrometer located at an angle of 0 deg with respect to the beam direction. In all the reactions studied light charged particles with an energy close to the respective calculated kinematic limit for a two-body exit channel are produced with relatively great probability. The results obtained make it possible to draw some conclusions about the reaction mechanism involving the emission of light charged particles

Efficient Solar Energy Harvesting and Storage through a Robust Photocatalyst Driving Reversible Redox Reactions.

Science.gov (United States)

Zhou, Yangen; Zhang, Shun; Ding, Yu; Zhang, Leyuan; Zhang, Changkun; Zhang, Xiaohong; Zhao, Yu; Yu, Guihua

2018-06-14

Simultaneous solar energy conversion and storage is receiving increasing interest for better utilization of the abundant yet intermittently available sunlight. Photoelectrodes driving nonspontaneous reversible redox reactions in solar-powered redox cells (SPRCs), which can deliver energy via the corresponding reverse reactions, present a cost-effective and promising approach for direct solar energy harvesting and storage. However, the lack of photoelectrodes having both high conversion efficiency and high durability becomes a bottleneck that hampers practical applications of SPRCs. Here, it is shown that a WO 3 -decorated BiVO 4 photoanode, without the need of extra electrocatalysts, can enable a single-photocatalyst-driven SPRC with a solar-to-output energy conversion efficiency as high as 1.25%. This SPRC presents stable performance over 20 solar energy storage/delivery cycles. The high efficiency and stability are attributed to the rapid redox reactions, the well-matched energy level, and the efficient light harvesting and charge separation of the prepared BiVO 4 . This demonstrated device system represents a potential alternative toward the development of low-cost, durable, and easy-to-implement solar energy technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Contribution to the study of low-energy (d,p) reactions on light nuclei; Contribution a l'etude des reactions (d,p) a basse energie sur noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Nguyen Van, S [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1967-05-15

This work is carried out with a view to analysing low energy (d,p) reactions on light nuclei measured at Grenoble or Algiers and suggesting a direct mechanism. The distorted wave approximation has been applied; this requires the development of programmes for the IBM 7044 computer at the 'Institut des Mathematiques Appliquees' in Grenoble. The (d,p) reactions on {sup 14}N, {sup 9}Be, {sup 22}Ne and {sup 16}O are dealt with. A calculation of the interference of the direct interaction and of resonating effects has been applied to {sup 16}O. (author) [French] Ce travail a pour but d'analyser les reactions (d,p) a basse energie sur noyaux legers, mesurees a Grenoble ou a Alger et qui suggerent un mecanisme direct. L'approximation des ondes distordues a ete appliquee, necessitant la mise au point de programmes sur l'ordinateur IBM 7044 de l'Institut des Mathematiques Appliquees de Grenoble. Des reactions (d,p) sur {sup 14}N, {sup 9}Be, {sup 22}Ne et {sup 16}O sont traitees. Un calcul de l'interference de l'interaction directe et des effets resonnants a ete applique a {sup 16}O. (auteur)

Energy Considerations for Plasma-Assisted N-Fixation Reactions

Directory of Open Access Journals (Sweden)

Aikaterini Anastasopoulou

2014-09-01

Full Text Available In a time of increasing concerns about the immense energy consumption and poor environmental performance of contemporary processes in the chemical industry, there is great need to develop novel sustainable technologies that enhance energy efficiency. There is abundant chemical literature on process innovations (laboratory-scale around the plasma reactor itself, which, naturally, is the essential part to be intensified to achieve a satisfactory process. In essence, a plasma process needs attention beyond reaction engineering towards the process integration side and also with strong electrical engineering focus. In this mini-review, we have detailed our future focus on the process and energy intensification of plasma-based N-fixation. Three focal points are mainly stressed throughout the review: (I the integration of renewable energy; (II the power supply system of plasma reactors and (III process design of industrial plasma-assisted nitrogen fixation. These different enabling strategies will be set in a holistic and synergetic picture so as to improve process performance.

Analysis for mass distribution of proton-induced reactions in intermediate energy range

CERN Document Server

Xiao Yu Heng

2002-01-01

The mass and charge distribution of residual products produced in the spallation reactions needs to be studied, because it can provide useful information for the disposal of nuclear waste and residual radioactivity generated by the spallation neutron target system. In present work, the Many State Dynamical Model (MSDM) is based on the Cascade-Exciton Model (CEM). The authors use it to investigate the mass distribution of Nb, Au and Pb proton-induced reactions in energy range from 100 MeV to 3 GeV. The agreement between the MSDM simulations and the measured data is good in this energy range, and deviations mainly show up in the mass range of 90 - 150 for the high energy proton incident upon Au and Pb

Experimental investigation of dd reaction in range of ultralow energies using Z-pinch

International Nuclear Information System (INIS)

Bystritskij, V.M.; Grebenyuk, V.M.; Parzhitskij, S.S.

1998-01-01

Results of the experiments to measure the dd reaction cross section in the range of deuteron collision energies from 0.1 keV to 1.5 keV using Z-pinch technique are presented. The experiment was performed at the Pulsed Ion Beam Accelerator of the High-Current Electronics Institute in Tomsk. The dd fusion neutrons were registered by scintillation detectors using time-of-flight method and BF 3 detectors of thermal neutrons. At 90% confidence level, the upper limits of the neutron producing dd reaction cross sections are obtained for average deuteron collision energies of 0.11, 0.34, 0.37 and 1.46 keV. The results demonstrate that high-intensity pulsed accelerators with a generator current of 2-3 MA allow the dd reaction cross sections to be measured in the range of deuteron collision energies from 0.8 keV to 3 keV

Fission in intermediate energy heavy ion reactions

International Nuclear Information System (INIS)

Wilhelmy, J.B.; Begemann-Blaich, M.; Blaich, T.; Boissevain, J.; Fowler, M.M.; Gavron, A.; Jacak, B.V.; Lysaght, P.S.; Britt, H.C.; Fields, D.J.; Hansen, L.F.; Lanier, R.G.; Massoletti, D.J.; Namboodiri, M.M.; Remington, B.A.; Sangster, T.C.; Struble, G.L.; Webb, M.L.; Chan, Y.D.; Dacai, A.; Harmon, A.; Leyba, J.; Pouliot, J.; Stokstad, R.G.; Hansen, O.; Levine, M.J.; Thorn, C.E.; Trautmann, W.; Dichter, B.; Kaufman, S.; Videbaek, F.; Fraenkel, Z.; Mamane, G.; Cebra, D.; Westfall, G.D.

1989-01-01

A systematic study of reaction mechanisms at intermediate energies (50-100 MeV/A) has been performed at the Lawrence Berkeley Laboratory's BeValac using medium weight projectiles on medium and heavy element targets. A gas and plastic phoswich detector system was employed which gave large geometric coverage and a wide dynamic response. The particles identified with the gas detectors could be characterized into three components - intermediate mass fragments (IMF), fission fragments (FF) and heavy residues (HR). Major observed features are: The reaction yields are similar in the 50 to 100 MeV/A range, central collisions have high multiplicty of IMF's with broad angular correlations consistent with a large participant region, effects of final state Coulomb interactions are observed and give information on the size and temporal behavior of the source, true fission yields are dependent on target fissility and correlated with relatively peripheral collisions. Analysis of fission and evaporation yields implies limiting conditions for which fission decay remains a viable deexcitation channel. (orig.)

Fission in intermediate energy heavy ion reactions

International Nuclear Information System (INIS)

Wilhelmy, J.B.; Begemann-Blaich, M.; Blaich, T.

1989-01-01

A systematic study of reaction mechanisms at intermediate energies (50--100 MeV/A) has been performed at the Lawrence Berkeley Laboratory's BeValac using medium weight projectiles on medium and heavy element targets. A gas and plastic phoswich detector system was employed which gave large geometric coverage and a wide dynamic response. The particles identified with the gas detectors could be characterized into three components - intermediate mass fragments (IMF), fission fragments (FF) and heavy residues (HR). Major observed features are: the reaction yields are similar in the 50 to 100 MeV/A range, central collisions have high multiplicity of IMF's with broad angular correlations consistent with a large participant region, effects of final state Coulomb interactions are observed and give information on the size and temporal behavior of the source, true fission yields are dependent on target fissility and correlated with relatively peripheral collisions. Analysis of fission and evaporation yields implies limiting conditions for which fission decay remains a viable deexcitation channel. 7 figs

Convergence to Equilibrium in Energy-Reaction-Diffusion Systems Using Vector-Valued Functional Inequalities

Science.gov (United States)

Mielke, Alexander; Mittnenzweig, Markus

2018-04-01

We discuss how the recently developed energy dissipation methods for reaction diffusion systems can be generalized to the non-isothermal case. For this, we use concave entropies in terms of the densities of the species and the internal energy, where the importance is that the equilibrium densities may depend on the internal energy. Using the log-Sobolev estimate and variants for lower-order entropies as well as estimates for the entropy production of the nonlinear reactions, we give two methods to estimate the relative entropy by the total entropy production, namely a somewhat restrictive convexity method, which provides explicit decay rates, and a very general, but weaker compactness method.

Energy flow and particle spectra with respect to the reaction plane for Au+Au collisions at AGS energies

International Nuclear Information System (INIS)

Zhang Yingchao; Wessels, J.P.

1995-01-01

Transverse energy flow is studied by exploiting the near 4π calorimetric coverage of experiment E877. A Fourier decomposition of the azimuthal transverse energy distributions in different regions of pseudorapidity is performed as a function of the centrality in order to describe the event shape. The extracted coefficients are compared to model predictions. Using the E877 forward spectrometer, triple differential cross section for protons and π + are measured with respect to the reaction plane determined by calorimeters. The variation of slope parameters at different orientations to the reaction plane is obtained by fitting to thermal Boltzmann distributions. (orig.)

A model for consecutive spallation and fragmentation reactions in inverse kinematics at relativistic energies

International Nuclear Information System (INIS)

Napolitani, P.; Tassan-Got, L.; Bernas, M.; Armbruster, P.

2003-04-01

Secondary reactions induced by relativistic beams in inverse kinematics in a thick target are relevant in several fields of experimental physics and technology, like secondary radioactive beams, production of exotic nuclei close to the proton drip line, and cross-section measurements for applications of spallation reactions for energy production and incineration of nuclear wastes. A general mathematical formulation is presented and successively applied as a tool to disentangle the primary reaction yields from the secondary production in the measurement of fission of a 238 U projectile impinging on a proton target at the energy of 1 A GeV. (orig.)

The TDF System for Thermonuclear Plasma Reaction Rates, Mean Energies and Two-Body Final State Particle Spectra

International Nuclear Information System (INIS)

Warshaw, S I

2001-01-01

The rate of thermonuclear reactions in hot plasmas as a function of local plasma temperature determines the way in which thermonuclear ignition and burning proceeds in the plasma. The conventional model approach to calculating these rates is to assume that the reacting nuclei in the plasma are in Maxwellian equilibrium at some well-defined plasma temperature, over which the statistical average of the reaction rate quantity σv is calculated, where σ is the cross-section for the reaction to proceed at the relative velocity v between the reacting particles. This approach is well-understood and is the basis for much nuclear fusion and astrophysical nuclear reaction rate data. The Thermonuclear Data File (TDF) system developed at the Lawrence Livermore National Laboratory (Warshaw 1991), which is the topic of this report, contains data on the Maxwellian-averaged thermonuclear reaction rates for various light nuclear reactions and the correspondingly Maxwellian-averaged energy spectra of the particles in the final state of those reactions as well. This spectral information closely models the output particle and energy distributions in a burning plasma, and therefore leads to more accurate computational treatments of thermonuclear burn, output particle energy deposition and diagnostics, in various contexts. In this report we review and derive the theoretical basis for calculating Maxwellian-averaged thermonuclear reaction rates, mean particle energies, and output particle spectral energy distributions for these reactions in the TDF system. The treatment of the kinematics is non-relativistic. The current version of the TDF system provides exit particle energy spectrum distributions for two-body final state reactions only. In a future report we will discuss and describe how output particle energy spectra for three- and four-body final states can be developed for the TDF system. We also include in this report a description of the algorithmic implementation of the TDF

Low Energy Electrons as Probing Tool for Astrochemical Reaction Mechanisms

Science.gov (United States)

Hendrik Bredehöft, Jan; Swiderek, Petra; Hamann, Thorben

The complexity of molecules found in space varies widely. On one end of the scale of molecular complexity is the hydrogen molecule H2 . Its formation from H atoms is if not understood than at least thoroughly investigated[1]. On the other side of said spectrum the precursors to biopolymers can be found, such as amino acids[2,3], sugars[4], lipids, cofactors[5], etc, and the kerogen-like organic polymer material in carbonaceous meteorites called "black stuff" [6]. These have also received broad attention in the last decades. Sitting in the middle between these two extremes are simple molecules that are observed by radio astronomy throughout the Universe. These are molecules like methane (CH4 ), methanol (CH3 OH), formaldehyde (CH2 O), hydrogen cyanide (HCN), and many many others. So far more than 40 such species have been identified.[7] They are often used in laboratory experiments to create larger complex molecules on the surface of simulated interstellar dust grains.[2,8] The mechanisms of formation of these observed starting materials for prebiotic chemistry is however not always clear. Also the exact mechanisms of formation of larger molecules in photochemical experiments are largely unclear. This is mostly due to the very complex chemistry going on which involves many different radicals and ions. The creation of radicals and ions can be studied in detail in laboratory simulations. They can be created in a setup mimicking interstellar grain chemistry using slow electrons. There is no free electron radiation in space. What can be found though is a lot of radiation of different sorts. There is electromagnetic radiation (UV light, X-Rays, rays, etc.) and there is particulate radiation as well in the form of high energy ions. This radiation can provide energy that drives chemical reactions in the ice mantles of interstellar dust grains. And while the multitude of different kinds of radiation might be a little confusing, they all have one thing in common: Upon

Effect of projectile on incomplete fusion reactions at low energies

Directory of Open Access Journals (Sweden)

Sharma Vijay R.

2017-01-01

Full Text Available Present work deals with the experimental studies of incomplete fusion reaction dynamics at energies as low as ≈ 4 - 7 MeV/A. Excitation functions populated via complete fusion and/or incomplete fusion processes in 12C+175Lu, and 13C+169Tm systems have been measured within the framework of PACE4 code. Data of excitation function measurements on comparison with different projectile-target combinations suggest the existence of ICF even at slightly above barrier energies where complete fusion (CF is supposed to be the sole contributor, and further demonstrates strong projectile structure dependence of ICF. The incomplete fusion strength functions for 12C+175Lu, and 13C+169Tm systems are analyzed as a function of various physical parameters at a constant vrel ≈ 0.053c. It has been found that one neutron (1n excess projectile 13C (as compared to 12C results in less incomplete fusion contribution due to its relatively large negative α-Q-value, hence, α Q-value seems to be a reliable parameter to understand the ICF dynamics at low energies. In order to explore the reaction modes on the basis of their entry state spin population, the spin distribution of residues populated via CF and/or ICF in 16O+159Tb system has been done using particle-γ coincidence technique. CF-α and ICF-α channels have been identified from backward (B and forward (F α-gated γspectra, respectively. Reaction dependent decay patterns have been observed in different α emitting channels. The CF channels are found to be fed over a broad spin range, however, ICF-α channels was observed only for high-spin states. Further, the existence of incomplete fusion at low bombarding energies indicates the possibility to populate high spin states

Effect of projectile on incomplete fusion reactions at low energies

Science.gov (United States)

Sharma, Vijay R.; Shuaib, Mohd.; Yadav, Abhishek; Singh, Pushpendra P.; Sharma, Manoj K.; Kumar, R.; Singh, Devendra P.; Singh, B. P.; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.; Prasad, R.

2017-11-01

Present work deals with the experimental studies of incomplete fusion reaction dynamics at energies as low as ≈ 4 - 7 MeV/A. Excitation functions populated via complete fusion and/or incomplete fusion processes in 12C+175Lu, and 13C+169Tm systems have been measured within the framework of PACE4 code. Data of excitation function measurements on comparison with different projectile-target combinations suggest the existence of ICF even at slightly above barrier energies where complete fusion (CF) is supposed to be the sole contributor, and further demonstrates strong projectile structure dependence of ICF. The incomplete fusion strength functions for 12C+175Lu, and 13C+169Tm systems are analyzed as a function of various physical parameters at a constant vrel ≈ 0.053c. It has been found that one neutron (1n) excess projectile 13C (as compared to 12C) results in less incomplete fusion contribution due to its relatively large negative α-Q-value, hence, α Q-value seems to be a reliable parameter to understand the ICF dynamics at low energies. In order to explore the reaction modes on the basis of their entry state spin population, the spin distribution of residues populated via CF and/or ICF in 16O+159Tb system has been done using particle-γ coincidence technique. CF-α and ICF-α channels have been identified from backward (B) and forward (F) α-gated γspectra, respectively. Reaction dependent decay patterns have been observed in different α emitting channels. The CF channels are found to be fed over a broad spin range, however, ICF-α channels was observed only for high-spin states. Further, the existence of incomplete fusion at low bombarding energies indicates the possibility to populate high spin states

The 3rd Nordic meeting on high energy reactions in nuclei

International Nuclear Information System (INIS)

Green, A.M.; Kullander, S.

Abstracts of the 31 lectures given at the meeting are presented. Major emphasis was placed on the nucleon-nucleon and nucleon-antinucleon interaction in bound and unbound systems. Four of the ten sessions were devoted to this subject. Two sessions contained lecture and seminars on 'Isobars in nuclei', two were devoted to hadron-nucleus reactions, one to high-energy heavy-ion reactions and one to new developments of experimental tools. This latter session had two talks, one about channeling with GeV particles and the other about the planned low-energy antiproton facility LEAR at CERN. Talks of more general character were 'The experimental programme at the CERN SC', 'Accelerator produced nuclear fuel' and 'The upsilons, a new family of quark-antiquark bound state'. (JIW)

Inclusive quasielastic neutrino reactions in 12C and 16O at intermediate energies

International Nuclear Information System (INIS)

Singh, S.K.; Oset, E.

1993-01-01

Inclusive quasielastic neutrino (antineutrino) reactions on 12 C and 16 O at intermediate energies (50< E<400 MeV) are studied to investigate the effects of the nuclear medium on the total cross section and the energy spectrum of the outgoing leptons. The calculations are done in the local density approximation and various nuclear effects like Pauli blocking, Fermi motion, and strong-interaction renormalizations due to the presence of nucleons are taken into account. The corrections due to Coulomb effects are included which have been hitherto neglected in inclusive reactions. The results presented here are applicable to the inclusive reactions with neutrino beams planned to look for neutrino oscillations in the Los Alamos experiments or the experiments with underground detectors looking for atmospheric or solar flare neutrinos

A Review of Study on Thermal Energy Transport System by Synthesis and Decomposition Reactions of Methanol

Science.gov (United States)

Liu, Qiusheng; Yabe, Akira; Kajiyama, Shiro; Fukuda, Katsuya

The study on thermal energy transport system by synthesis and decomposition reactions of methanol was reviewed. To promote energy conservation and global environment protection, a two-step liquid-phase methanol synthesis process, which starts with carbonylation of methanol to methyl formate, then followed by the hydrogenolysis of the formate, was studied to recover wasted or unused discharged heat from industrial sources for the thermal energy demands of residential and commercial areas by chemical reactions. The research and development of the system were focused on the following three points. (1) Development of low-temperature decomposition and synthetic catalysts, (2) Development of liquid phase reactor (heat exchanger accompanying chemical reaction), (3) Simulation of the energy transport efficiency of entire system which contains heat recovery and supply sections. As the result of the development of catalyst, promising catalysts which agree with the development purposes for the methyl formate decomposition reaction and the synthetic reaction are being developed though some studies remain for the methanol decomposition and synthetic reactions. In the fundamental development of liquid phase reactor, the solubilities of CO and H2 gases in methanol and methyl formate were measured by the method of total pressure decrease due to absorption under pressures up to 1500kPa and temperatures up to 140°C. The diffusivity of CO gas in methanol was determined by measuring the diameter and solution time of single CO bubbles in methanol. The chemical reaction rate of methanol synthesis by hydrogenolysis of methyl formate was measured using a plate-type of Raney copper catalyst in a reactor with rectangular channel and in an autoclave reactor. The reaction characteristics were investigated by carrying out the experiments at various temperatures, flow rates and at various catalyst development conditions. We focused on the effect of Raney copper catalyst thickness on the liquid

Intermediate- and high-energy reactions of uranium with neon and carbon

International Nuclear Information System (INIS)

McGaughey, P.L.

1982-11-01

Target fragment production from the interactions of 1.0, 3.0, 4.8, and 12 GeV 12 C and 5.0, 8.0, 20, and 42 GeV 20 Ne with uranium has been measured using off-line gamma-ray spectroscopic techniques. The experimental charge and mass yield distributions are generally consistent with the concepts of limiting fragmentation and factorization at energies of 3.0 GeV and above. The total projectile kinetic energy was found to be the relevant scaling parameter for the comparison of reactions induced by projectiles of different sizes. Light fragments with mass number less than 60 were found to violate limiting fragmentation, and had excitation functions that were strongly increasing with projectile energy until 8.0 to 12.0 GeV. With the 1.0 GeV 12 C beam the pattern of mass yields was quite different from that of all the other reactions, with the normal peak in the fission mass region (80 < A < 145), but with much lower yields below mass number 60 and between mass numbers 145 and 210, indicating that these fragments are formed primarily in very energetic reactions in which large excitation energies are transferred to and significant amounts of mass are removed from the target nucleus. Theoretical predictions of the intra-nuclear cascade, nuclear fireball, and nuclear firestreak models are compared with the experimental results. The intra-nuclear cascade and nuclear firestreak models are both able to predict the general shapes of the experimental distributions, with the exception of the yields for the lightest fragments

Reaction channels of 6,7Li+28Si at near-barrier energies

International Nuclear Information System (INIS)

Pakou, A; Rusek, K; Nicolis, N G; Alamanos, N; Doukelis, G; Gillibert, A; Kalyva, G; Kokkoris, M; Lagoyannis, A; Musumarra, A; Papachristodoulou, C; Perdikakis, G; Pierroutsakou, D; Pollacco, E C; Spyrou, A; Zarkadas, Ch

2005-01-01

The production of α-particles in the reactions 6,7 Li+ 28 Si was studied as a means to disentangle the various reaction channels at near-barrier energies. The competition between compound and direct reactions was determined by using the shape of angular distributions and statistical model calculations. DWBA calculations were also performed to probe the various direct channels. It was found that, approaching barrier, transfer channels are the most dominant for both reactions. For 7 Li+ 28 Si d-transfer is one of the contributing channels without excluding t-transfer, while for 6 Li+ 28 Si, n-transfer and p-transfer have substantial contribution but without excluding d-transfer

Theoretical study on pp → pnπ+ reaction at medium energies

International Nuclear Information System (INIS)

Ouyang, Zhen; Xie, Jujun; Zou, Bingsong; Xu, Hushan

2009-01-01

The pp → pnπ + reaction is a channel with the largest total cross section for pp collision in COSY/CSR energy region. In this work, we investigate individual contributions from various N* and Δ* resonances with mass up to about 2 GeV for the pp → pnπ + reaction. We extend a resonance model, which can reproduce the observed total cross section quite well, to give theoretical predictions of various differential cross sections for the present reaction at T p = 2.88 GeV. It could serve as a reference for identifying new physics in the future experiments at HIRFL-CSR. (author)

Direct reactions induced by 16O on 208Pb at high incident energy

International Nuclear Information System (INIS)

Mermaz, M.C.

1978-01-01

Direct reactions induced by 16 O mainly on 208 Pb at 20 MeV/nucleon are reviewed. The quasi-elastic transfer reaction, such as one-proton and one-neutron transfer respectively leading to 209 Bi and 209 Pb single-particle-states, is first discussed, the fragmentation of 16 O projectile on heavy targets is then envisaged. The one-nucleon transfer can be described within the framework of one-step processes using the DWBA formalism to calculate the cross sections. At high incident energy (312.6 MeV), transfer reactions involving nucleons from the deeper 1p 3/2 orbit of 16 O are kinematically favoured and well observed. At 20 MeV/A and above, a large part of the reaction cross sections seems to be due to the fragmentation of the projectile; more especially, an abrasion-ablation model have to be used in order to explain the general trend of the data (energy spectra and angular distribution)

Development of linear free energy relationships for aqueous phase radical-involved chemical reactions.

Science.gov (United States)

Minakata, Daisuke; Mezyk, Stephen P; Jones, Jace W; Daws, Brittany R; Crittenden, John C

2014-12-02

Aqueous phase advanced oxidation processes (AOPs) produce hydroxyl radicals (HO•) which can completely oxidize electron rich organic compounds. The proper design and operation of AOPs require that we predict the formation and fate of the byproducts and their associated toxicity. Accordingly, there is a need to develop a first-principles kinetic model that can predict the dominant reaction pathways that potentially produce toxic byproducts. We have published some of our efforts on predicting the elementary reaction pathways and the HO• rate constants. Here we develop linear free energy relationships (LFERs) that predict the rate constants for aqueous phase radical reactions. The LFERs relate experimentally obtained kinetic rate constants to quantum mechanically calculated aqueous phase free energies of activation. The LFERs have been applied to 101 reactions, including (1) HO• addition to 15 aromatic compounds; (2) addition of molecular oxygen to 65 carbon-centered aliphatic and cyclohexadienyl radicals; (3) disproportionation of 10 peroxyl radicals, and (4) unimolecular decay of nine peroxyl radicals. The LFERs correlations predict the rate constants within a factor of 2 from the experimental values for HO• reactions and molecular oxygen addition, and a factor of 5 for peroxyl radical reactions. The LFERs and the elementary reaction pathways will enable us to predict the formation and initial fate of the byproducts in AOPs. Furthermore, our methodology can be applied to other environmental processes in which aqueous phase radical-involved reactions occur.

Intramolecular energy transfer and mode-specific effects in unimolecular reactions of 1,2-difluoroethane

Science.gov (United States)

Raff, Lionel M.

1989-06-01

The unimolecular decomposition reactions of 1,2-difluoroethane upon mode-specific excitation to a total internal energy of 7.5 eV are investigated using classical trajectory methods and a previously formulated empirical potential-energy surface. The decomposition channels for 1,2-difluoroethane are, in order of importance, four-center HF elimination, C-C bond rupture, and hydrogen-atom dissociation. This order is found to be independent of the particular vibrational mode excited. Neither fluorine-atom nor F2 elimination reactions are ever observed even though these dissociation channels are energetically open. For four-center HF elimination, the average fraction of the total energy partitioned into internal HF motion varies between 0.115-0.181 depending upon the particular vibrational mode initially excited. The internal energy of the fluoroethylene product lies in the range 0.716-0.776. Comparison of the present results with those previously obtained for a random distribution of the initial 1,2-difluoroethane internal energy [J. Phys. Chem. 92, 5111 (1988)], shows that numerous mode-specific effects are present in these reactions in spite of the fact that intramolecular energy transfer rates for this system are 5.88-25.5 times faster than any of the unimolecular reaction rates. Mode-specific excitation always leads to a total decomposition rate significantly larger than that obtained for a random distribution of the internal energy. Excitation of different 1,2-difluoroethane vibrational modes is found to produce as much as a 51% change in the total decomposition rate. Mode-specific effects are also seen in the product energy partitioning. The rate coefficients for decomposition into the various channels are very sensitive to the particular mode excited. A comparison of the calculated mode-specific effects with the previously determined mode-to-mode energy transfer rate coefficients [J. Chem. Phys. 89, 5680 (1988)] shows that, to some extent, the presence of mode

Potential design modifications for the High Yield Lithium Injection Fusion Energy (HYLIFE) reaction chamber

International Nuclear Information System (INIS)

Pitts, J.H.; Hovingh, J.; Meier, W.R.; Monsler, M.J.; Powell, E.G.; Walker, P.E.

1979-01-01

Generation of electric power from inertial confinement fusion requires a reaction chamber. One promising type, the High Yield Lithium Injection Fusion Energy (HYLIFE) chamber, includes a falling array of liquid lithium jets. These jets act as: (1) a renewable first wall and blanket to shield metal components from x-ray and neutron exposure, (2) a tritium breeder to replace tritium burned during the fusion process, and (3) an absorber and transfer medium for fusion energy. Over 90% of the energy produced in the reaction chamber is absorbed in the lithium jet fall. Design aspects are included

Reactions with weakly bound nuclei at near barrier energies

International Nuclear Information System (INIS)

Nanal, Vandana

2014-01-01

In reactions with weakly bound nuclei, the effect of breakup on fusion process has attracted much attention in recent years. The experimental study shows that breakup channel leads to suppression of complete fusion at above barrier energies due to loss of flux. The fusion barrier distribution can provide a further insight into understanding the influence of coupling to the breakup channels. Similar information could be obtained from the elastic and quasielastic (QEL) scattering because of the conservation of the reaction flux (i.e. R+T= 1), where R is the reflection probability and T is the transmission probability. Thus, quasi-elastic scattering at backward angles is the counterpart of the fusion process and it is expected that the barrier distributions extracted from two processes, namely, QEL and fusion should be similar. While this is true for tightly bound reaction systems, in reactions involving weakly bound projectiles significant differences have been observed for QEL barrier distributions with and without inclusion of breakup processes. This talk will present the recent results for fusion and quasi-elastic scattering in "6","7Li + "1"9"7Au system. Developmental efforts towards a momentum achromatic separator, MARIE, to extract projectile-like secondary ion beams following the reactions of heavy-ion beams from superconducting LINAC booster at Mumbai will also be presented. (author)

Proton-proton reaction rates at extreme energies

International Nuclear Information System (INIS)

Nagano, Motohiko

1993-01-01

Results on proton-antiproton reaction rates (total cross-section) at collision energies of 1.8 TeV from experiments at Fermilab have suggested a lower rate of increase with energy compared to the extrapolation based on results previously obtained at CERN's proton-antiproton collider (CERN Courier, October 1991). Now an independent estimate of the values for the proton-proton total cross-section for collision energies from 5 to 30 TeV has been provided by the analysis of cosmic ray shower data collected over ten years at the Akeno Observatory operated by the Institute for Cosmic Ray Research of University of Tokyo. These results are based on the inelastic cross-section for collisions of cosmic ray protons with air nuclei at energies in the range10 16-18 eV. A new extensive air shower experiment was started at Akeno, 150 km west of Tokyo, in 1979 with a large array of detectors, both on the ground and under a 1-metre concrete absorber. This measured the total numbers of electrons and muons of energies above 1GeV for individual showers with much better accuracy than before. Data collection was almost continuous for ten years without any change in the triggering criteria for showers above10 16 eV. The mean free path for proton-air nuclei collisions has been determined from the zenith angle of the observed frequency of air showers which have the same effective path length for development in the atmosphere and the same primary energy

On the Effect of Microwave Energy on Lipase-Catalyzed Polycondensation Reactions

Directory of Open Access Journals (Sweden)

Alessandro Pellis

2016-09-01

Full Text Available Microwave energy (MWe is, nowadays, widely used as a clean synthesis tool to improve several chemical reactions, such as drug molecule synthesis, carbohydrate conversion and biomass pyrolysis. On the other hand, its exploitation in enzymatic reactions has only been fleetingly investigated and, hence, further study of MWe is required to reach a precise understanding of its potential in this field. Starting from the authors’ experience in clean synthesis and biocatalyzed reactions, this study sheds light on the possibility of using MWe for enhancing enzyme-catalyzed polycondensation reactions and pre-polymer formation. Several systems and set ups were investigated involving bulk and organic media (solution phase reactions, different enzymatic preparations and various starting bio-based monomers. Results show that MWe enables the biocatalyzed synthesis of polyesters and pre-polymers in a similar way to that reported using conventional heating with an oil bath, but in a few cases, notably bulk phase polycondensations under intense microwave irradiation, MWe leads to a rapid enzyme deactivation.

The astrophysical S factor for dd reaction at ultralow energies

International Nuclear Information System (INIS)

Bystritskii, Vit.M.; Bystritsky, V.M.; Grebenyuk, V.M.

2001-01-01

The experimental results of measurements of the astrophysical S factor for dd reaction at very low deuteron collision energies using liner plasma technique are presented. The experiment was fulfilled at the high-current generator of the High-Current Electronics Institute (Tomsk, Russia). The measured values of S factors for the deuteron collision energies 1.80, 2.06, and 2.27 keV are S dd = 114 ± 68, 64 ± 30, and 53 ± 16 keV b, respectively. The corresponding cross sections for dd reaction, described as a product of the barrier factor and measured astrophysical S factor are: σ dd n (E col = 1.80 keV) = (4.3 ± 2.6) x 10 -33 cm 2 ; σ dd n (E col = 2.06 keV) = (9.8 ± 4.6) x 10 -33 cm 2 ; σ dd n (E col = 2.27 keV) = (2.1 ± 0.6) x 10 -32 cm 2 [ru

Zero-point energy, tunnelling, and vibrational adiabaticity in the Mu + H2 reaction

Science.gov (United States)

Mielke, Steven L.; Garrett, Bruce C.; Fleming, Donald G.; Truhlar, Donald G.

2015-01-01

Isotopic substitution of muonium for hydrogen provides an unparalleled opportunity to deepen our understanding of quantum mass effects on chemical reactions. A recent topical review in this journal of the thermal and vibrationally state-selected reaction of Mu with H2 raises a number of issues that are addressed here. We show that some earlier quantum mechanical calculations of the Mu + H2 reaction, which are highlighted in this review, and which have been used to benchmark approximate methods, are in error by as much as 19% in the low-temperature limit. We demonstrate that an approximate treatment of the Born-Oppenheimer diagonal correction that was used in some recent studies is not valid for treating the vibrationally state-selected reaction. We also discuss why vibrationally adiabatic potentials that neglect bend zero-point energy are not a useful analytical tool for understanding reaction rates, and why vibrationally non-adiabatic transitions cannot be understood by considering tunnelling through vibrationally adiabatic potentials. Finally, we present calculations on a hierarchical family of potential energy surfaces to assess the sensitivity of rate constants to the quality of the potential surface.

Contribution to the study of low-energy (d,p) reactions on light nuclei; Contribution a l'etude des reactions (d,p) a basse energie sur noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Nguyen Van, S. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1967-05-15

This work is carried out with a view to analysing low energy (d,p) reactions on light nuclei measured at Grenoble or Algiers and suggesting a direct mechanism. The distorted wave approximation has been applied; this requires the development of programmes for the IBM 7044 computer at the 'Institut des Mathematiques Appliquees' in Grenoble. The (d,p) reactions on {sup 14}N, {sup 9}Be, {sup 22}Ne and {sup 16}O are dealt with. A calculation of the interference of the direct interaction and of resonating effects has been applied to {sup 16}O. (author) [French] Ce travail a pour but d'analyser les reactions (d,p) a basse energie sur noyaux legers, mesurees a Grenoble ou a Alger et qui suggerent un mecanisme direct. L'approximation des ondes distordues a ete appliquee, necessitant la mise au point de programmes sur l'ordinateur IBM 7044 de l'Institut des Mathematiques Appliquees de Grenoble. Des reactions (d,p) sur {sup 14}N, {sup 9}Be, {sup 22}Ne et {sup 16}O sont traitees. Un calcul de l'interference de l'interaction directe et des effets resonnants a ete applique a {sup 16}O. (auteur)

Angular evolution of peripheral heavy ion reactions at intermediate energies

International Nuclear Information System (INIS)

Blumenfeld, Y.; Chomaz, P.; Frascaria, N.; Garron, J.P.; Jacmart, J.C; Roynette, J.C

1985-01-01

Energy spectra and angular distributions of projectile-like fragments have been measured in the vicinity of the grazing angle for the 40 Ar+ 40 Ca and 40 Ar+ 208 Pb reactions at 44MeV/nucleon. Measurements of the 40 Ar+ 40 Ca system at 27MeV/nucleon and 20 Ne+ 208 Pb reaction at 44MeV/nucleon at one angle have also been performed. For fragments with charge and mass close to the projectile numerous deviations from the standard fragmentation model have been observed including rapidly changing shapes of the angular distributions with the fragment mass. Moreover the isotopic distributions and mean fragment velocities are strongly dependent on detection angle. A surface transfer reaction component dominant at the grazing angle can be separated from a second component which cannot be entirely accounted for by a simple fragmentation mechanism

Transfer of energy from irradiated crystals to redox reactions: iodide/bromate and nitrite/bromate systems

International Nuclear Information System (INIS)

Arnikar, H.J.; Madhava Rao, B.S.; Bedekar, M.J.

1978-01-01

Earlier it had been shown by the authors that some of the redox reactions, which do not take place at room temperature can be induced by γ radiation. The yields are proportional to the dose. Results reported here show that instead of direct irradiation, the energy stored in irradiated crystals in the form of F and hole centres can be available, in part, in effecting redox reactions. The mechanism of such an energy transfer is discussed with reference to reactions in the I - +BrO 3 - and NO 2 - +BrO 3 - systems due to the addition of irradiated NaCl. (author)

Computed potential energy surfaces for chemical reactions

Science.gov (United States)

Walch, Stephen P.

1988-01-01

The minimum energy path for the addition of a hydrogen atom to N2 is characterized in CASSCF/CCI calculations using the (4s3p2d1f/3s2p1d) basis set, with additional single point calculations at the stationary points of the potential energy surface using the (5s4p3d2f/4s3p2d) basis set. These calculations represent the most extensive set of ab initio calculations completed to date, yielding a zero point corrected barrier for HN2 dissociation of approx. 8.5 kcal mol/1. The lifetime of the HN2 species is estimated from the calculated geometries and energetics using both conventional Transition State Theory and a method which utilizes an Eckart barrier to compute one dimensional quantum mechanical tunneling effects. It is concluded that the lifetime of the HN2 species is very short, greatly limiting its role in both termolecular recombination reactions and combustion processes.

(3He,α) reaction mechanism at high energy and neutron inner shell structure

International Nuclear Information System (INIS)

Wiele, J. van de.

1980-01-01

The ( 3 He,α) reaction on 12 C, 16 O, 28 Si, 58 Ni, 90 Zr, 118 Sn, 124 Sn and 208 Pb targets has been studied at Esub( 3 He) = 217 MeV (or 205 MeV) in order to investigate the reaction mechanism at high energy and large momentum transfer. The reaction yields large cross sections at very forward angles and strongly enhances the largest orbital momentum transfer. The angular distribution shapes are well reproduced in the frame-work of the Z-R- D.W.B.A. analysis if we use a unique empirical α-potential: Vsub(α)(Esub(α)) = Vsub( 3 He)(3/4 Esub(α)) + Vsub(n)(1/4 Esub(α)). The excitation energy spectra have been measured up to 100 MeV in the residual light and medium nuclei and up to about 16 MeV in heavy nuclei. In addition to the well-known low-lying levels, peaks or broad structures are observed for each nucleus at higher excitation energies. They are attributed to pick up from inner shells: 1s( 11 C and 15 O), 1p( 27 Si), 1d5/2 + 1p( 57 Ni), 1f7/2( 89 Zr) 1g9/2 117 Sn, 123 Sn and 1h11/2( 207 Pb). Selectivity and localization of direct and indirect pick up ( 3 He,α) reactions were studied. Finite range calculations show that this reaction is not very sensitive to the details of the range from function but only to D 0 coefficient and range R. A microscopic α-nucleus optical potential calculated with n-n dependent and independent density forces is able to reproduce both elastic scattering and pick up reaction angular distributions [fr

Progress in applyiong the FKK multistep reaction theory to intermediate-energy data evaluation

International Nuclear Information System (INIS)

Chadwick, M.B.; Young, P.G.

1994-01-01

Recent developments to the physics modeling in the FKK-GNASH code system are reviewed. We describe modifications to include a linking of multistep direct and multistep compound processes, which are important when the incident energy is less than about 30 MeV. A model for multiple preequilibrium emission is given, and compared with experimental measurements of proton reactions on 90 Zr at 160 MeV. We also give some preliminary observations concerning FKK calculations which use both normal and non-normal DWBA matrix elements. We describe the application of the FKK-GNASH code to a range of nuclear data applications, including intermediate energy reactions of importance in the accelerator transmutation of waste, and fast neutron and proton cancer radiation treatment. We outline areas where further work is needed for the accurate modeling of nuclear reactions using the FKK theory

Reaching to a featured formula to deduce the energy of the heaviest particles producing from the controlled thermonuclear fusion reactions

Science.gov (United States)

Majeed, Raad H.; Oudah, Osamah N.

2018-05-01

Thermonuclear fusion reaction plays an important role in developing and construction any power plant system. Studying the physical behavior for the possible mechanism governed energies released by the fusion products to precise understanding the related kinematics. In this work a theoretical formula controlled the general applied thermonuclear fusion reactions is achieved to calculating the fusion products energy depending upon the reactants physical properties and therefore, one can calculate other parameters governed a given reaction. By using this formula, the energy spectrum of 4He produced from T-3He fusion reaction has been sketched with respect to reaction angle and incident energy ranged from (0.08-0.6) MeV.

Specialized reactions: reactions at intermediate energies: Baryon--nucleus collisions, 150 MeV--1 GeV

International Nuclear Information System (INIS)

Igo, G.

1974-01-01

The high energy collision approximation proposed by Glauber to describe experimental data at the upper end of the intermediate range is reviewed. Some aspects of the model which limit its validity are outlined. Elastic scattering of protons from light nuclei is discussed in the framework of the Glauber model. For data in the energy region near 200 MeV, the plane wave impulse approximation (PWIA) and the distorted wave impulse approximation (DWIA) are applied. Quasielastic scattering is treated by considering (p,p') and (p,2p) reactions with light nuclei. A short discussion of the high resolution spectrometer facility at LAMPF and the SPES 1 facility at Saturne is given. (46 figures, 3 tables, 102 references) (U.S.)

The 2H(e, e' p)n reaction at large energy transfers

NARCIS (Netherlands)

Willering, Hendrik Willem

2003-01-01

At the ELSA accelerator facillity in Bonn, Germany, we have measured the deutron "breakup" reaction 2H(e,e' p)n at four-momentum transfers around Q2 = -0 .20(GeV/c)2 with an electron beam energy of E0 = 1.6 GeV. The cross section has been determined for energy transfers extending from the

Experimental studies of keV energy neutron-induced reactions relevant to astrophysics and nuclear physics

Energy Technology Data Exchange (ETDEWEB)

Shima, T.; Kii, T.; Kikuchi, T.; Okazaki, F.; Kobayashi, T.; Baba, T.; Nagai, Y. [Tokyo Inst. of Tech. (Japan). Faculty of Science; Igashira, M.

1997-03-01

Nuclear reactions induced by keV energy neutrons provide a plenty of informations for studies of both astrophysics and nuclear physics. In this paper we will show our experimental studies of neutron- induced reactions of light nuclei in the keV energy region by means of a pulsed keV neutron beam and high-sensitivity detectors. Also we will discuss astrophysical and nuclear-physical consequences by using the obtained results. (author)

Direct Energy Supply to the Reaction Mixture during Microwave-Assisted Hydrothermal and Combustion Synthesis of Inorganic Materials

Directory of Open Access Journals (Sweden)

Roberto Rosa

2014-05-01

Full Text Available The use of microwaves to perform inorganic synthesis allows the direct transfer of electromagnetic energy inside the reaction mixture, independently of the temperature manifested therein. The conversion of microwave (MW radiation into heat is useful in overcoming the activation energy barriers associated with chemical transformations, but the use of microwaves can be further extended to higher temperatures, thus creating unusual high-energy environments. In devising synthetic methodologies to engineered nanomaterials, hydrothermal synthesis and solution combustion synthesis can be used as reference systems to illustrate effects related to microwave irradiation. In the first case, energy is transferred to the entire reaction volume, causing a homogeneous temperature rise within a closed vessel in a few minutes, hence assuring uniform crystal growth at the nanometer scale. In the second case, strong exothermic combustion syntheses can benefit from the application of microwaves to convey energy to the reaction not only during the ignition step, but also while it is occurring and even after its completion. In both approaches, however, the direct interaction of microwaves with the reaction mixture can lead to practically gradient-less heating profiles, on the basis of which the main observed characteristics and properties of the aforementioned reactions and products can be explained.

The astrophysical S-factor for dd-reactions at keV-energy range

International Nuclear Information System (INIS)

Bystritskii, V.; Bystritsky, V.; Chaikovsky, S.

2001-01-01

The experimental results of measurements of the astrophysical S-factor for dd-reaction at keV-energy range collision energies using liner plasma technique are presented. The experiments were carried out at the high current generator of the Institute of High-Current Electronics in Tomsk, Russia. The measured values of the S-factors for the deuteron collision energies 1.80, 2.06 and 2.27 keV are S dd =(114±68), (64±30), (53±16) b x keV, respectively. The corresponding cross sections for dd-reactions, described as a product of the barrier factor and measured astrophysical S-factor, are σ dd n (E col =1.80 keV)=(4.3±2.6) x 10 -33 cm 2 ; σ dd n (E col =2.06 keV)=(9.8±4.6) x 10 -33 cm 2 ; σ dd n (E col =2.27 keV)=(2.1±0.6) x 10 -32 cm 2 . (orig.) [de

Nuclear chemistry research of high-energy nuclear reactions at Carnegie-Mellon University, 1961--1977. Summary report

International Nuclear Information System (INIS)

Caretto, A.A. Jr.

1977-11-01

The activities and the results of research in the study of high energy nuclear reactions carried out at Carnegie Institute of Technology from 1957 to 1967 and at Carnegie-Mellon University from 1967 to 1977 are summarized. A complete list of all publications, doctoral dissertations, and reports resulting from the research of this project is also included. A major part of the report is a review of the research activities and results. The objective of the research of this project was the study of reactions initiated by projectiles of energy above about 100 MeV. The main effort was the investigation of simple nuclear reactions with the objective to deduce reaction mechanisms. These reactions were also used as probes to determine the nuclear structure of the target. In addition, a number of studies of spallation reactions were undertaken which included the determination of excitation functions and recoil properties. Recent research activities which have involved the study of pion induced reactions as well as reactions initiated by heavy ions is also discussed

Intermediate energy heavy ion reactions. A program for CELSIUS

International Nuclear Information System (INIS)

Jakobsson, B.

1986-02-01

The accelerator system under construction in Uppsala with the ECR-source + the K equals 200 synchrocyclotron + the CELSIUS synchrotron ring for storage, cooling and acceleration opens up possibilities for a very fruitful heavy ion physics program. Some recently obtained results and some recent ideas on intermediate energy reactions are discussed and speculations are made about some experiments where the unconventional qualities of CELSIUS beams could be utilized. (author)

The decay of hot nuclei formed in La-induced reactions at intermediate energies

International Nuclear Information System (INIS)

Libby, B.; Mignerey, A.C.; Madani, H.; Marchetti, A.A.; Colonna, M.; DiToro, M.

1992-01-01

The decay of hot nuclei formed in lanthanum-induced reactions utilizing inverse kinematics has been studied from E/A = 35 to 55 MeV. At each bombarding energy studied, the probability for the multiple emission of complex fragments has been found to be independent of target. Global features (total charge, source velocity) of the reaction La + Al at E/A = 45 MeV have been reproduced by coupling a dynamical model to study the collision stage of the reaction to a statistical model of nuclear decay

Fusion cross sections for 6,7Li + 24Mg reactions at energies below and above the barrier

International Nuclear Information System (INIS)

Ray, M.; Mukherjee, A.; Pradhan, M. K.; Kshetri, Ritesh; Sarkar, M. Saha; Dasmahapatra, B.; Palit, R.; Majumdar, I.; Joshi, P. K.; Jain, H. C.

2008-01-01

Measurement of fusion cross sections for the 6,7 Li + 24 Mg reactions by the characteristic γ-ray method has been done at energies from below to well above the respective Coulomb barriers. The fusion cross sections obtained from these γ-ray cross sections for the two systems are found to agree well with the total reaction cross sections at low energies. The relatively large difference between total cross sections and measured fusion cross sections at higher energies is consistent with the fact that other channels, in particular breakup, open up with an increase of bombarding energy. The breakup channel, however, appears not to have any influence on fusion cross sections. The critical angular momenta (l cr ) deduced from the fusion cross sections are found to have an energy dependence similar to other Li-induced reactions

Compound nuclei, binary decay, and multifragmentation in intermediate-energy heavy-ion reactions

International Nuclear Information System (INIS)

Moretto, L.G.; Wozniak, G.J.

1988-07-01

Hot compound nuclei, frequently produced in intermediate-energy reactions through a variety of processes, are shown to be an important and at times dominant source of complex fragments. 13 refs., 12 figs

Parameterization of pion production and reaction cross sections at LAMPF energies

International Nuclear Information System (INIS)

Burman, R.L.; Smith, E.S.

1989-05-01

A parameterization of pion production and reaction cross sections is developed for eventual use in modeling neutrino production by protons in a beam stop. Emphasis is placed upon smooth parameterizations for proton energies up to 800 MeV, for all pion energies and angles, and for a wide range of materials. The resulting representations of the data are well-behaved and can be used for extrapolation to regions where there are no measurements. 22 refs., 16 figs., 2 tabs

Reaction kinetics aspect of U3O8 kernel with gas H2 on the characteristics of activation energy, reaction rate constant and O/U ratio of UO2 kernel

International Nuclear Information System (INIS)

Damunir

2007-01-01

The reaction kinetics aspect of U 3 O 8 kernel with gas H 2 on the characteristics of activation energy, reaction rate constant and O/U ratio of UO 2 kernel had been studied. U 3 O 8 kernel was reacted with gas H 2 in a reduction furnace at varied reaction time and temperature. The reaction temperature was varied at 600, 700, 750 and 850 °C with a pressure of 50 mmHg for 3 hours in gas N 2 atmosphere. The reation time was varied at 1, 2, 3 and 4 hours at a temperature of 750 °C using similar conditions. The reaction product was UO 2 kernel. The reaction kinetic aspect between U 3 O 8 and gas H 2 comprised the minimum activation energy (ΔE), the reaction rate constant and the O/U ratio of UO 2 kernel. The minimum activation energy was determined from a straight line slope of equation ln [{D b . R o {(1 - (1 - X b ) ⅓ } / (b.t.Cg)] = -3.9406 x 10 3 / T + 4.044. By multiplying with the straight line slope -3.9406 x 10 3 , the ideal gas constant (R) 1.985 cal/mol and the molarity difference of reaction coefficient 2, a minimum activation energy of 15.644 kcal/mol was obtained. The reaction rate constant was determined from first-order chemical reaction control and Arrhenius equation. The O/U ratio of UO 2 kernel was obtained using gravimetric method. The analysis result of reaction rate constant with chemical reaction control equation yielded reaction rate constants of 0.745 - 1.671 s -1 and the Arrhenius equation at temperatures of 650 - 850 °C yielded reaction rate constants of 0.637 - 2.914 s -1 . The O/U ratios of UO 2 kernel at the respective reaction rate constants were 2.013 - 2.014 and the O/U ratios at reaction time 1 - 4 hours were 2.04 - 2.011. The experiment results indicated that the minimum activation energy influenced the rate constant of first-order reaction and the O/U ratio of UO 2 kernel. The optimum condition was obtained at reaction rate constant of 1.43 s -1 , O/U ratio of UO 2 kernel of 2.01 at temperature of 750 °C and reaction time of 3

Applications of Skyrme energy-density functional to fusion reactions spanning the fusion barriers

International Nuclear Information System (INIS)

Liu Min; Wang, Ning; Li Zhuxia; Wu Xizhen; Zhao Enguang

2006-01-01

The Skyrme energy density functional has been applied to the study of heavy-ion fusion reactions. The barriers for fusion reactions are calculated by the Skyrme energy density functional with proton and neutron density distributions determined by using restricted density variational (RDV) method within the same energy density functional together with semi-classical approach known as the extended semi-classical Thomas-Fermi method. Based on the fusion barrier obtained, we propose a parametrization of the empirical barrier distribution to take into account the multi-dimensional character of real barrier and then apply it to calculate the fusion excitation functions in terms of barrier penetration concept. A large number of measured fusion excitation functions spanning the fusion barriers can be reproduced well. The competition between suppression and enhancement effects on sub-barrier fusion caused by neutron-shell-closure and excess neutron effects is studied

Resonance capture reactions with a total energy detector

International Nuclear Information System (INIS)

Macklin, R.L.

1978-01-01

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

Generating Converged Accurate Free Energy Surfaces for Chemical Reactions with a Force-Matched Semiempirical Model.

Science.gov (United States)

Kroonblawd, Matthew P; Pietrucci, Fabio; Saitta, Antonino Marco; Goldman, Nir

2018-04-10

We demonstrate the capability of creating robust density functional tight binding (DFTB) models for chemical reactivity in prebiotic mixtures through force matching to short time scale quantum free energy estimates. Molecular dynamics using density functional theory (DFT) is a highly accurate approach to generate free energy surfaces for chemical reactions, but the extreme computational cost often limits the time scales and range of thermodynamic states that can feasibly be studied. In contrast, DFTB is a semiempirical quantum method that affords up to a thousandfold reduction in cost and can recover DFT-level accuracy. Here, we show that a force-matched DFTB model for aqueous glycine condensation reactions yields free energy surfaces that are consistent with experimental observations of reaction energetics. Convergence analysis reveals that multiple nanoseconds of combined trajectory are needed to reach a steady-fluctuating free energy estimate for glycine condensation. Predictive accuracy of force-matched DFTB is demonstrated by direct comparison to DFT, with the two approaches yielding surfaces with large regions that differ by only a few kcal mol -1 .

Universal trend for heavy-ion total reaction cross sections at energies above the Coulomb barrier

International Nuclear Information System (INIS)

Tavares, O.A.P.; Medeiros, E.L.; Morcelle, V.

2010-06-01

Heavy-ion total reaction cross section measurements for more than one thousand one hundred reaction cases covering 61 target nuclei in the range 6 Li- 238 U, and 158 projectile nuclei from 2 H up to 84 Kr (mostly exotic ones) have been analysed in a systematic way by using an empirical, three-parameter formula which is applicable to cases for projectile kinetic energies above the Coulomb barrier. The analysis has shown that the average total nuclear binding energy per nucleon of the interacting nuclei and their radii are the chief quantities which describe the cross section patterns. A great number of cross section data (87%) has been quite satisfactorily reproduced by the proposed formula, therefore total reaction cross section predictions for new, not yet experimentally investigated reaction cases can be obtained within 25 percent (or much less) of uncertainty (author)

Multiple scattering in the nuclear rearrangement reactions at medium energy

International Nuclear Information System (INIS)

Tekou, A.

1980-09-01

It is shown that the multiple scattering mechanism is very important in the transfer of the large momenta involved in the nuclear rearrangement reactions at medium energy. In contrast to the usual belief, the reaction cross-section is not very sensitive to the high momenta components of the nuclear wave function. The multiple scattering mechanism is especially important in 4 He(p,d) 3 He reaction around 800 MeV. Here the collisions involving two nucleons of the target nucleus are dominant. The triple collisions contribution is also important. The four collision contribution is negligible in the forward direction and sizeable at large angles. Thus, using the K.M.T. approach in DWBA calculations, the second order term of the optical potential must be included. So, is it not well established that the second term of the K.M.T. optical potential is important for the proton elastic scattering on light nuclei. (author)

Pauli-blocking effect in two-body collisions dominates the in-medium effects in heavy-ion reactions near Fermi energy

Energy Technology Data Exchange (ETDEWEB)

Xing, Yong-Zhong, E-mail: yzxing@tsnu.edu.cn [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); Zhang, H.F. [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Liu, Xiao-Bin [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); Zheng, Yu-Ming [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); China Institute of Atomic Energy, P.O. Box 275(18), Beijing 102413 (China)

2017-01-15

The dissipation phenomenon in the heavy-ion reaction at incident energy near Fermi energy is studied by simulating the reactions {sup 129}Xe + {sup 129}Sn and {sup 58}Ni + {sup 58}Ni with isospin-dependent quantum molecular dynamics model (IQMD). The isotropy ratio in terms of transverse and longitudinal energies of the free protons emitted in the final states of these reactions is quantitatively analyzed to explore the in-medium correlation of the binary collisions. Comparison of the calculations with the experimental data recently released by INDRA collaboration exhibits that the ratio is very sensitive to the Pauli blocking effect in two-body collisions and Pauli exclusion principle is indispensable in the theoretical simulations for the heavy-ion reactions near the Fermi energy.

Reaction energetics on long-range corrected density functional theory: Diels-Alder reactions.

Science.gov (United States)

Singh, Raman K; Tsuneda, Takao

2013-02-15

The possibility of quantitative reaction analysis on the orbital energies of long-range corrected density functional theory (LC-DFT) is presented. First, we calculated the Diels-Alder reaction enthalpies that have been poorly given by conventional functionals including B3LYP functional. As a result, it is found that the long-range correction drastically improves the reaction enthalpies. The barrier height energies were also computed for these reactions. Consequently, we found that dispersion correlation correction is also crucial to give accurate barrier height energies. It is, therefore, concluded that both long-range exchange interactions and dispersion correlations are essentially required in conventional functionals to investigate Diels-Alder reactions quantitatively. After confirming that LC-DFT accurately reproduces the orbital energies of the reactant and product molecules of the Diels-Alder reactions, the global hardness responses, the halves of highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps, along the intrinsic reaction coordinates of two Diels-Alder reactions were computed. We noticed that LC-DFT results satisfy the maximum hardness rule for overall reaction paths while conventional functionals violate this rule on the reaction pathways. Furthermore, our results also show that the HOMO-LUMO gap variations are close to the reaction enthalpies for these Diels-Alder reactions. Based on these results, we foresee quantitative reaction analysis on the orbital energies. Copyright © 2012 Wiley Periodicals, Inc.

Free Energy Contribution Analysis Using Response Kernel Approximation: Insights into the Acylation Reaction of a Beta-Lactamase.

Science.gov (United States)

Asada, Toshio; Ando, Kanta; Bandyopadhyay, Pradipta; Koseki, Shiro

2016-09-08

A widely applicable free energy contribution analysis (FECA) method based on the quantum mechanical/molecular mechanical (QM/MM) approximation using response kernel approaches has been proposed to investigate the influences of environmental residues and/or atoms in the QM region on the free energy profile. This method can evaluate atomic contributions to the free energy along the reaction path including polarization effects on the QM region within a dramatically reduced computational time. The rate-limiting step in the deactivation of the β-lactam antibiotic cefalotin (CLS) by β-lactamase was studied using this method. The experimentally observed activation barrier was successfully reproduced by free energy perturbation calculations along the optimized reaction path that involved activation by the carboxylate moiety in CLS. It was found that the free energy profile in the QM region was slightly higher than the isolated energy and that two residues, Lys67 and Lys315, as well as water molecules deeply influenced the QM atoms associated with the bond alternation reaction in the acyl-enzyme intermediate. These facts suggested that the surrounding residues are favorable for the reactant complex and prevent the intermediate from being too stabilized to proceed to the following deacylation reaction. We have demonstrated that the free energy contribution analysis should be a useful method to investigate enzyme catalysis and to facilitate intelligent molecular design.

Investigations of (. cap alpha. ,. cap alpha. 'x) reactions up to 40 MeV/A bombarding energy

Energy Technology Data Exchange (ETDEWEB)

Machner, H [Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.). Inst. fuer Kernphysik; Feldmeier, H [ed.

1980-02-01

The angle integrated cross sections of continuous nucleon spectra from light ion induced reactions could be well reproduced within nonequilibrium statistical models. An extended exciton model even allows the calculations of angular distributions. Energy and linear momentum dissipation are treated with the help of a generalized master equation. The Exciton Coalescence Model (ECM) reproduces the angular distributions of complex particles emitted in nuclear reactions at moderate energies.

Contribution to the phenomenological study of two-body reactions at high energy; Contribution a l'etude phenomenologique des reactions a deux corps a haute energie

Energy Technology Data Exchange (ETDEWEB)

Cohen-Tannoudji, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

A phenomenological model suited for the description of arbitrary two-body reactions at high energies is presented and applied to the analysis of {pi} - nucleon, K - nucleon, et K-bar - nucleon scattering.The idea is that the Regge-pole model does not take into account the whole content of the unitarity relation and has to be modified, as is currently done in one-particle exchange models, so that it may include absorptive corrections.In terms of a rather economical set of free parameters,we obtain a satisfactory agreement with all available data, including the recent evidence for a nonvanishing polarization in {pi}{sup -} p {pi}{sup 0} n reaction. We then reinterpret our parametrization of the amplitudes in terms of poles and branch points in the complex angular-momentum plane for the crossed channel. (author) [French] Un modele phenomenologique adapte a la description des reactions a deux corps a haute energie est presente et applique a l'analyse des diffusions {pi} - nucleon, K - nucleon, et K-bar - nucleon. L'idee essentielle est que le modele d'echange de poles de Regge ne tient pas compte du contenu total de la relation d'unitarite et doit etre modifie, comme cela a ete propose dans le cas de l'echange de particules, de facon a tenir compte de corrections de type absortif. Au moyen d'un ensemble relativement economique de parametres libres nous obtenons un accord satisfaisant avec tous les resultats disponibles, y compris l'existence recemment mise en evidence d'une polarisation non nulle dans la reaction {pi}{sup -} p {pi}{sup 0} n. Nous interpretons notre fa n d'ecrire les amplitudes au moyen de poles et de points de branchement dans le plan complexe du moment angulaire pour la voie croisee. (auteur)

Multifragmentation in intermediate energy 129Xe-induced heavy-ion reactions

International Nuclear Information System (INIS)

Tso, Kin.

1996-05-01

The 129 Xe-induced reactions on nat Cu, 89 Y, 165 Ho, and 197 Au at bombarding energies of E/A = 40 ampersand 60 MeV have been studied theoretically and experimentally in order to establish the underlying mechanism of multifragmentation at intermediate energy heavy-Ion collisions. Nuclear disks formed in central heavy-ion collisions, as simulated by means of Boltzmann-like kinetic equations, break up into several fragments due to a new kind of Rayleigh-like surface instability. A sheet of liquid, stable in the limit of non-interacting surfaces, is shown to become unstable due to surface-surface interactions. The onset of this instability is determined analytically. A thin bubble behaves like a sheet and is susceptible to the surface instability through the crispation mode. The Coulomb effects associated with the depletion of charges in the central cavity of nuclear bubbles are investigated. The onset of Coulomb instability is demonstrated for perturbations of the radial mode. Experimental intermediate-mass-fragment multiplicity distributions for the 129 Xe-induced reactions are shown to be binomial at each transverse energy. From these distributions, independent of the specific target, an elementary binary decay probability p can be extracted that has a thermal dependence. Thus it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with transverse energy implies a contraction of the emission time scale. The sensitivity of p to the lower Z threshold in the definition of intermediate-mass-fragments points to a physical Poisson simulations of the particle multiplicities show that the weak auto-correlation between the fragment multiplicity and the transverse energy does not distort a Poisson distribution into a binomial distribution. The effect of device efficiency on the experimental results has also been studied

Proton transfer and unimolecular decay in the low-energy-reaction dynamics of H3O+ with acetone

International Nuclear Information System (INIS)

Creasy, W.R.; Farrar, J.M.

1983-01-01

The title reaction has been studied at collision energies of 0.83 and 2.41 eV. Direct reaction dynamics have been observed at both energies and an increasingly high fraction of the total energy appears in product translation as the collision energy increases. This result is consistent with the concept of induced repulsive energy release, which becomes more effective as trajectories sample the corner of the potential energy surface. At the higher collision energy, the protonated acetone cation undergoes two unimolecular decay channels: C-C bond cleavage to CH 3 CO + and CH 4 , and C-O bond cleavagto C 3 H 5 + (presumably to allyl cation) and H 2 O. The CH 3 CO + channel, endothermic relative to ground state protonated acetone cations by 0.74 eV, appears to liberate 0.4 eV in relative product translation while the C 3 H 5 + channel, endothermic by 2.17 eV, liberates only 0.07 eV in relative translation. These results are discussed in terms of the location on the reaction coordinate and magnitudes of potential energy barriers to 1,3-hydrogen atoms shifts which must precede the bond cleavage processes

Universal trend for heavy-ion total reaction cross sections at energies above the Coulomb barrier

Energy Technology Data Exchange (ETDEWEB)

Tavares, O.A.P.; Medeiros, E.L., E-mail: emil@cbpf.b [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Morcelle, V. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica

2010-06-15

Heavy-ion total reaction cross section measurements for more than one thousand one hundred reaction cases covering 61 target nuclei in the range {sup 6}Li-{sup 238}U, and 158 projectile nuclei from {sup 2}H up to {sup 84}Kr (mostly exotic ones) have been analysed in a systematic way by using an empirical, three-parameter formula which is applicable to cases for projectile kinetic energies above the Coulomb barrier. The analysis has shown that the average total nuclear binding energy per nucleon of the interacting nuclei and their radii are the chief quantities which describe the cross section patterns. A great number of cross section data (87%) has been quite satisfactorily reproduced by the proposed formula, therefore total reaction cross section predictions for new, not yet experimentally investigated reaction cases can be obtained within 25 percent (or much less) of uncertainty (author)

Resonant Interaction, Approximate Symmetry, and Electromagnetic Interaction (EMI) in Low Energy Nuclear Reactions (LENR)

Science.gov (United States)

Chubb, Scott

2007-03-01

Only recently (talk by P.A. Mosier-Boss et al, in this session) has it become possible to trigger high energy particle emission and Excess Heat, on demand, in LENR involving PdD. Also, most nuclear physicists are bothered by the fact that the dominant reaction appears to be related to the least common deuteron(d) fusion reaction,d+d ->α+γ. A clear consensus about the underlying effect has also been illusive. One reason for this involves confusion about the approximate (SU2) symmetry: The fact that all d-d fusion reactions conserve isospin has been widely assumed to mean the dynamics is driven by the strong force interaction (SFI), NOT EMI. Thus, most nuclear physicists assume: 1. EMI is static; 2. Dominant reactions have smallest changes in incident kinetic energy (T); and (because of 2), d+d ->α+γ is suppressed. But this assumes a stronger form of SU2 symmetry than is present; d+d ->α+γ reactions are suppressed not because of large changes in T but because the interaction potential involves EMI, is dynamic (not static), the SFI is static, and because the two incident deuterons must have approximate Bose Exchange symmetry and vanishing spin. A generalization of this idea involves a resonant form of reaction, similar to the de-excitation of an atom. These and related (broken gauge) symmetry EMI effects on LENR are discussed.

Reaction Hamiltonian and state-to-state description of chemical reactions

International Nuclear Information System (INIS)

Ruf, B.A.; Kresin, V.Z.; Lester, W.A. Jr.

1985-08-01

A chemical reaction is treated as a quantum transition from reactants to products. A specific reaction Hamiltonian (in second quantization formalism) is introduced. The approach leads to Franck-Condon-like factor, and adiabatic method in the framework of the nuclear motion problems. The influence of reagent vibrational state on the product energy distribution has been studied following the reaction Hamiltonian method. Two different cases (fixed available energy and fixed translational energy) are distinguished. Results for several biomolecular reactions are presented. 40 refs., 5 figs

Reaction path analysis of sodium-water reaction phenomena in support of chemical reaction model development

International Nuclear Information System (INIS)

Kikuchi, Shin; Ohshima, Hiroyuki; Hashimoto, Kenro

2011-01-01

Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule to the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. The results are used as the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by JAEA toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR). (author)

High energy nuclear reactions ('Spallation') and their application in calculation of the Acceleration Driven Systems (ADS)

International Nuclear Information System (INIS)

Rossi, Pedro Carlos Russo

2011-01-01

This work presents a study of high energy nuclear reactions which are fundamental to dene the source term in accelerator driven systems. These nuclear reactions, also known as spallation, consist in the interaction of high energetic hadrons with nucleons in the atomic nucleus. The phenomenology of these reactions consist in two step. In the rst, the proton interacts through multiple scattering in a process called intra-nuclear cascade. It is followed by a step in which the excited nucleus, coming from the intranuclear cascade, could either, evaporates particles to achieve a moderate energy state or fission. This process is known as competition between evaporation and fission. In this work the main nuclear models, Bertini and Cugnon are reviewed, since these models are fundamental for design purposes of the source term in ADS, due to lack of evaluated nuclear data for these reactions. The implementation and validation of the calculation methods for the design of the source is carried out to implement the methodology of source design using the program MCNPX (Monte Carlo N-Particle eXtended), devoted to calculation of transport of these particles and the validation performed by an international cooperation together with a Coordinated Research Project (CRP) of the International Atomic Energy Agency and available jobs, in order to qualify the calculations on nuclear reactions and the de-excitation channels involved, providing a state of the art of design and methodology for calculating external sources of spallation for source driven systems. The CRISP, is a brazilian code for the phenomenological description of the reactions involved and the models implemented in the code were reviewed and improved to continue the qualification process. Due to failure of the main models in describing the production of light nuclides, the multifragmentation reaction model was studied. Because the discrepancies in the calculations of production of these nuclides are attributes to the

Energy dependence of the 3He(3He,π+)6Li reaction

International Nuclear Information System (INIS)

Le Bornec, Y.; Hibou, F.; Bimbot, L.; Hennino, T.; Jourdain, J.C.; Reide, F.; Tatischeff, B.; Willis, N.; Aslanides, E.; Bergdolt, G.; Fassnacht, P.; Racca, C.; Boudard, A.; Bruge, G.; Lugol, J.C.

1983-01-01

The 3 He( 3 He, π + ) 6 Li reaction has been studied as a function of energy using the 3 He beam at SATURNE. Cross sections for the 6 Li ground state (1 + ) and 2.18 MeV (3 + ) levels have been obtained at 350, 420, 500 and 600 MeV incident energies at angles THETAsub(π)(lab)=15 0 and 40 0 . These results are compared with two theoretical predictions. (orig.)

Enhancing chemical reactions

Science.gov (United States)

Morrey, John R.

1978-01-01

Methods of enhancing selected chemical reactions. The population of a selected high vibrational energy state of a reactant molecule is increased substantially above its population at thermal equilibrium by directing onto the molecule a beam of radiant energy from a laser having a combination of frequency and intensity selected to pump the selected energy state, and the reaction is carried out with the temperature, pressure, and concentrations of reactants maintained at a combination of values selected to optimize the reaction in preference to thermal degradation by transforming the absorbed energy into translational motion. The reaction temperature is selected to optimize the reaction. Typically a laser and a frequency doubler emit radiant energy at frequencies of .nu. and 2.nu. into an optical dye within an optical cavity capable of being tuned to a wanted frequency .delta. or a parametric oscillator comprising a non-centrosymmetric crystal having two indices of refraction, to emit radiant energy at the frequencies of .nu., 2.nu., and .delta. (and, with a parametric oscillator, also at 2.nu.-.delta.). Each unwanted frequency is filtered out, and each desired frequency is focused to the desired radiation flux within a reaction chamber and is reflected repeatedly through the chamber while reactants are fed into the chamber and reaction products are removed therefrom.

Parameterization of α-nucleus total reaction cross section at intermediate energies

International Nuclear Information System (INIS)

Alvi, M A; Abdulmomen, M A

2008-01-01

Applying a Coulomb correction factor to the Glauber model we have derived a closed expression for α-nucleus total reaction cross section, σ R . Under the approximation of rigid projectile model, the elastic S-matrix element S el (b) is evaluated from the phenomenological N-α amplitude and a Gaussian fit to the Helm's model form factor. Excellent agreements with the experimental data have been achieved by performing two-parameter fits to the α-nucleus σ R data in the energy range about 75 to 193 MeV. One of the parameters was found to be energy independent while the other, as expected, shows the energy dependence similar to that of N-α total cross section.

A phenomenological study of the π- p → π0 n charge exchange reaction at high energy

International Nuclear Information System (INIS)

Michaud, Y.

1995-01-01

The aim of the study was to examine the behaviour of the proton-proton elastic scattering, for mass center energies around 10 GeV, and more especially to study the charge exchange reaction π - p → π 0 n for mass center energies between 3 and 20 GeV. A formalism based on the Glauber model has been used, and a Regge trajectory exchange term was introduced in the model in order to enable the description of the lower energy domain (inferior to 10 GeV) that is characterized by a large contribution of meson exchanges at the scattering amplitude. The Glauber model is then applied to the charge exchange reaction and the differential cross section is analyzed for a center mass energy comprised between 3 and 20 GeV, together with the polarization at 40 GeV/c. The approach is then validated through the study of the π - p → η n reaction. The size of the kernel of proton and pion components implied in the π - p → π 0 n reaction, is also investigated. 90 refs., 48 figs., 4 tabs., 5 appends

Probing the Energy Transfer Dynamics of Photosynthetic Reaction Center Complexes Through Hole-Burning and Single-Complex Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Riley, Kerry Joseph [Iowa State Univ., Ames, IA (United States)

2007-01-01

Photosynthesis is the process by which light energy is used to drive reactions that generate sugars to supply energy for cellular processes. It is one of the most important fundamental biological reactions and occurs in both prokaryotic (e.g. bacteria) and eukaryotic (e.g. plants and algae) organisms. Photosynthesis is also remarkably intricate, requiring the coordination of many different steps and reactions in order to successfully transform absorbed solar energy into a biochemical usable form of energy. However, the net reaction for all photosynthetic organisms can be reduced to the following, deceptively general, equation developed by Van Niel[1] H₂ - D + A_implies^hv A - H₂ + D where H₂-D is the electron donor, e.g. H₂O, H₂S. A is the electron acceptor, e.g. CO₂, and A-H₂ is the synthesized sugar. Amazingly, this simple net equation is responsible for creating the oxidizing atmosphere of Earth and the recycling of CO₂, both of which are necessary for the sustainment of the global ecosystem.

Considering a Threshold Energy in Reactive Transport Modeling of Microbially Mediated Redox Reactions in an Arsenic-Affected Aquifer

Directory of Open Access Journals (Sweden)

Marco Rotiroti

2018-01-01

Full Text Available The reductive dissolution of Fe-oxide driven by organic matter oxidation is the primary mechanism accepted for As mobilization in several alluvial aquifers. These processes are often mediated by microorganisms that require a minimum Gibbs energy available to conduct the reaction in order to sustain their life functions. Implementing this threshold energy in reactive transport modeling is rarely used in the existing literature. This work presents a 1D reactive transport modeling of As mobilization by the reductive dissolution of Fe-oxide and subsequent immobilization by co-precipitation in iron sulfides considering a threshold energy for the following terminal electron accepting processes: (a Fe-oxide reduction, (b sulfate reduction, and (c methanogenesis. The model is then extended by implementing a threshold energy on both reaction directions for the redox reaction pairs Fe(III reduction/Fe(II oxidation and methanogenesis/methane oxidation. The optimal threshold energy fitted in 4.50, 3.76, and 1.60 kJ/mol e− for sulfate reduction, Fe(III reduction/Fe(II oxidation, and methanogenesis/methane oxidation, respectively. The use of models implementing bidirectional threshold energy is needed when a redox reaction pair can be transported between domains with different redox potentials. This may often occur in 2D or 3D simulations.

Bombarding energy dependence of nucleon exchange and energy dissipation in the strongly damped reaction 209Bi + 136Xe

International Nuclear Information System (INIS)

Wilcke, W.W.; Schroeder, W.U.; Huizenga, J.R.; Birkelund, J.R.; Randrup, J.

1980-01-01

Although considerable progress has been achieved in the understanding of strongly damped reactions at energies several MeV/u above the Coulomb barrier, some important experimental results are not yet clearly understood. Among these is the degree of correlation between the nucleon exchange and the large energy losses observed. Experimental evidence suggesting nucleon exchange as described by a one-body model to be the major component of the dissipation mechanism is discussed. It is concluded that the previously unexplained bombarding energy dependence between energy loss and fragment charge dispersion can be understood on the basis of a nucleon exchange model, provided the Pauli exclusion principle is taken into account. No necessity is seen to invoke further energy dissipation mechanisms. 7 figures

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1980-February 14, 1981

International Nuclear Information System (INIS)

1981-02-01

The stereochemistry of high energy 18 F, /sup 34m/Cl, and 76 Br substitution reactions involving enantiomeric molecules in the gas and condensed phase is studied. The gas to condensed state transition in halogen high energy chemistry, involving chlorine, bromine, and iodine activated by the (n,γ) and (I.T.) processes in halomethanes, saturated and unsaturated hydrocarbons is being investigated in more detail. Special attention is given to defining the nature of the enhancement yields in the condensed phase. High energy halogen reactions in liquid and frozen aqueous solutions of organic and biomolecular solutes are studied in an attempt to learn more about these reactions. The applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Special attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as indicators of solute-solute interactions in liquid and frozen aqueous solutions of halogenated bases and nucleosides are being developed. Experiments are designed to explain the mechanisms of the radioprotection offered biomolecular solutes trapped within the frozen ice lattice. Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular solutes in liquid and frozen aqueous solutions are studied. The high energy reactions of iodine with the isomers of pentene have been studied in low pressure gaseous systems employing additives and rare gas moderators and liquid systems. Reactivity of excited complex formation and structural effects of electrophilic iodine attack on the pi-bond systems are studied

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1980-February 14, 1981

Energy Technology Data Exchange (ETDEWEB)

1981-02-01

The stereochemistry of high energy /sup 18/F, /sup 34m/Cl, and /sup 76/Br substitution reactions involving enantiomeric molecules in the gas and condensed phase is studied. The gas to condensed state transition in halogen high energy chemistry, involving chlorine, bromine, and iodine activated by the (n,..gamma..) and (I.T.) processes in halomethanes, saturated and unsaturated hydrocarbons is being investigated in more detail. Special attention is given to defining the nature of the enhancement yields in the condensed phase. High energy halogen reactions in liquid and frozen aqueous solutions of organic and biomolecular solutes are studied in an attempt to learn more about these reactions. The applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Special attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as indicators of solute-solute interactions in liquid and frozen aqueous solutions of halogenated bases and nucleosides are being developed. Experiments are designed to explain the mechanisms of the radioprotection offered biomolecular solutes trapped within the frozen ice lattice. Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular solutes in liquid and frozen aqueous solutions are studied. The high energy reactions of iodine with the isomers of pentene have been studied in low pressure gaseous systems employing additives and rare gas moderators and liquid systems. Reactivity of excited complex formation and structural effects of electrophilic iodine attack on the pi-bond systems are studied.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1978--February 14, 1979

International Nuclear Information System (INIS)

Rack, E.P.

1979-02-01

High energy reactions of halogen atoms or ions, activated by nuclear transformations, were studied in gaseous, high pressure and condensed phase saturated and unsaturated hydrocarbons, halomethanes and other organic systems in order to better understand the mechanisms and dynamics of high energy monovalent species. The experimental and theoretical program consists of six interrelated areas: (1) the reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure and liquid systems; (2) the gas to condensed state transition in halogen high chemistry, involving bromine activated by the (n,γ) and (I.T.) processes in ethane was investigated in more detail; (3) systematics of halogen hot atom reactions. The reactions of 80 Br/sup m/, 80 Br, 82 Br/sup m/ + 82 Br, 82 Br, 128 I, 130 I, and 130 I/sup m/ + 130 I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators; (4) kinetic theory applications of high energy reactions and mathematical development of caging mechanisms were developed; (5) the sterochemistry of 38 Cl substitution reactions involving diastereomeric 1,2-dichloro-1,2-difluorethane in liquid mixtures was completed, suggesting that the stereochemical course of the substitution process is controlled by the properties of the solvent molecules; and (6) the applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems was continued, especially involving aluminum and vanadium trace determinations

A phenomenological study of the {pi}{sup -} p {yields} {pi}{sup 0} n charge exchange reaction at high energy; Etude phenomenologique de la reaction d`echange de charge {pi}{sup -} p {yields} {pi}{sup 0} n a haute energie

Energy Technology Data Exchange (ETDEWEB)

Michaud, Y

1995-09-21

The aim of the study was to examine the behaviour of the proton-proton elastic scattering, for mass center energies around 10 GeV, and more especially to study the charge exchange reaction {pi}{sup -} p {yields} {pi}{sup 0} n for mass center energies between 3 and 20 GeV. A formalism based on the Glauber model has been used, and a Regge trajectory exchange term was introduced in the model in order to enable the description of the lower energy domain (inferior to 10 GeV) that is characterized by a large contribution of meson exchanges at the scattering amplitude. The Glauber model is then applied to the charge exchange reaction and the differential cross section is analyzed for a center mass energy comprised between 3 and 20 GeV, together with the polarization at 40 GeV/c. The approach is then validated through the study of the {pi}{sup -} p {yields} {eta} n reaction. The size of the kernel of proton and pion components implied in the {pi}{sup -} p {yields} {pi}{sup 0} n reaction, is also investigated. 90 refs., 48 figs., 4 tabs., 5 appends.

Final stage of high energy hadron-nucleus nuclear collision reactions

International Nuclear Information System (INIS)

Strugal'ski, Z.; Jedrzejec, H.; Strugalska-Gola, E.; Mulas, E.

1996-01-01

The final or 'slow' stage of the hadron-nucleus collision reactions at high energy is considered on the basis of the collision mechanism prompted experimentally. The transmutation process of the damaged target nucleus into nucleons and stable nuclear fragments is discussed. Relations between intensities or multiplicities n p of the emitted fast protons and the mean intensities or multiplicities b > of the evaporated nucleons and nuclear fragments are presented. 14 refs

Light energy conversion by photocatalytic reaction

Energy Technology Data Exchange (ETDEWEB)

Fujishima, Akira; Yamagata, Sadamu [Univ. of Tokyo (Japan)

1989-01-01

The photocatalytic reaction, to be made to a suspended semiconductor powder system, was explained in summary. By using semiconductor as an electrode for the electrolyzation, etc. and projecting light on it to generate photoelectromotive force, a photocell can be composed. eg., by composing titanium oxide electrode, n-type semiconductor and platinum electrode, and irradiating light on the former electrode to generate electric current, oxygen and hydrogen are produced from the titanium oxide electrode and platinum electrode, respectively, which means the possibility of obtainment of clean energy from water as raw material. Such a wet type photocell, easy to produce, is active also in research. With white titanium oxide powder being suspended in water solution, hydrogen is produced by projecting light into it. Such a semiconductor is called photocatalyst, in which the research has been widely developed, mainly by taking notice of the hydrogen production on reduction side, since 1972. The photocatalysis using colloid and, differently, that doing heteropolyacid are also taken notice of. 24 refs., 6 figs.

High energy reactions in normal metabolism and ageing of animals

International Nuclear Information System (INIS)

Avdonina, E.N.; Nesmeyanov, N.

1983-01-01

Processes involving reactions on highly excited states are thought to be of great importance for normal metabolism and aging. Excess energy of the organism is transferred to result in the formation of highly excited states of macromolecules. UV, visible light or ionizing radiation created partially by the organism itself can change metabolic process rates. According to the authors, aging is associated with the defects of macromolecules owing to high energy processes. Gerontological changes in biological materials result from the elimination of low molecular weight molecules and from the formation of unsaturated compounds. Crosslinking of the compounds, accumulation of collagen and connective tissues, the energetic overload of the organism are listed as important features of aging. (V.N.)

The dynamics of the Hg + Br2 reaction: elucidation of the reaction mechanism for the Br exchange reaction.

Science.gov (United States)

Jambrina, P G; Menéndez, M; Aoiz, F J

2017-06-28

In spite of its importance in the Hg atmospheric chemistry, the dynamics of the Hg + Br 2 → HgBr + Br reaction is poorly understood. In this article, we have carried out a comprehensive study of the reaction mechanism of this reaction by means of quasiclassical trajectories (QCTs) on an existing ab initio potential energy surface (PES). The reaction has a non trivial dynamics, as a consequence of its large endothermicity, the presence of a deep potential well, and the competition between the Br exchange and the collision induced dissociation processes. Our calculations demonstrate that insertion is only relevant at energies just above the reaction threshold and that, at energies above 2.3 eV, HgBr formation typically takes place via a sort of frustrated dissociation. In order to compare directly with the results obtained in extensive cross molecular beam experiments for the homologous reaction with I 2 , angular distributions in the laboratory frame for Hg + Br 2 have been simulated under similar experimental conditions. The lack of agreement at the highest energies considered suggests that either the two reactions have substantially different mechanisms or that calculations on a single PES cannot account for the dynamics at those energies.

The energy spilling reactions of bacteria and other organisms.

Science.gov (United States)

Russell, James B

2007-01-01

For many years it was assumed that living organisms always utilized ATP in a highly efficient manner, but simple growth studies with bacteria indicated that the efficiency of biomass production was often at least 3-fold lower than the amount that would be predicted from standard biosynthetic pathways. The utilization of energy for maintenance could only explain a small portion of this discrepancy particularly when the growth rate was high. These ideas and thermodynamic arguments indicated that cells might have another avenue of energy utilization. This phenomenon has also been called 'uncoupling', 'spillage' and 'overflow metabolism', but 'energy spilling' is probably the most descriptive term. It appears that many bacteria spill energy, and the few that do not can be killed (large and often rapid decrease in viability), if the growth medium is nitrogen-limited and the energy source is in 'excess'. The lactic acid bacterium, Streptococcus bovis, is an ideal bacterium for the study of energy spilling. Because it only uses substrate level phosphorylation to generate ATP, ATP generation can be calculated with a high degree of certainty. It does not store glucose as glycogen, and its cell membrane can be easily accessed. Comparative analysis of heat production, membrane voltage, ATP production and Ohm's law indicated that the energy spilling reaction of S. bovis is mediated by a futile cycle of protons through the cell membrane. Less is known about Escherichia coli, but in this bacterium energy spilling could be mediated by a futile cycle of potassium or ammonium ions. Energy spilling is not restricted to prokaryotes and appears to occur in yeasts and in higher organisms. In man, energy spilling may be related to cancer, ageing, ischemia and cardiac failure. Copyright (c) 2007 S. Karger AG, Basel.

Low-Energy Nuclear Reactions Resulting as Picometer Interactions with Similarity to K-Shell Electron Capture

Science.gov (United States)

Hora, H.; Miley, G. H.; Li, X. Z.; Kelly, J. C.; Osman, F.

2006-02-01

Since the appeal by Brian Josephson at the meeting of the Nobel Laureates July 2004, it seems to be indicated to summarize the following serious, reproducible and confirmed observations on reactions of protons or deuterons incorporated in host metals such as palladium. Some reflections to Rutherford's discovery of nuclear physics, the Cockroft-Oliphant discovery of anomalous low-energy fusion reactions and the chemist Hahn's discovery of fission had to be included. Using gaseous atmosphere or discharges between palladium targets, rather significant results were seen e.g. from the "life after death" heat production of such high values per host atom that only nuclear reactions can be involved. This supports the earlier evaluation of neutron generation in fully reversible experiments with gas discharges hinting that a reasonable screening effect - preferably in the swimming electron layer - may lead to reactions at nuclear distances d of picometers with reaction probability times U of about megaseconds similar to the K-shell capture radioactivity. Further electrolytic experiments led to low-energy nuclear reactions (LENR) where the involvement of pollution could be excluded from the appearance of very seldom rare earth elements. A basically new theory for DD cross-sections is used to confirm the picometer-megasecond reactions of cold fusion. Other theoretical aspects are given from measured heavy element distributions similar to the standard abundance distribution, SAD, in the Universe with consequences on endothermic heavy nuclei generation, magic numbers and to quark-gluon plasmas.

Low-energy nuclear reactions resulting as parametric interactions with similarity to K-shell electron capture

International Nuclear Information System (INIS)

Hora, H.; Miley, G.H.; Li, X.Z.; Kelly, J.C.; Osman, F.

2006-01-01

Since the appeal by Brian Josephson at the meeting of the Nobel Laureates July 2004, it seems to be indicated to summarize the following serious, reproducible and confirmed observations on reactions of protons of deuterons incorporated in host metals such as palladium. Some reflections to Rutherford's discovery of nuclear physics, the Cockcroft Oliphant discovery of anomalous low-energy fusion reactions and the chemist Hahn's discovery of fission had to be included. Using gaseous atmosphere or discharges between palladium targets, rather significant results were seen e.g. from the 'life after death' heat production of such high values per host atom that only nuclear reactions can be involved. This supports the earlier evaluation of neutron generation in fully reversible experiments with gas discharges hinting that a reasonable screening effect - preferably in the swimming electron layer - may lead to reactions at nuclear distances d of pico-meters with reaction probability times U of about mega-seconds similar to the K-shell capture radioactivity. Further electrolytic experiments led to low-energy nuclear reactions (LENR) where the involvement of pollution could be excluded from the appearance of very seldom rare earth elements. A basically new theory for DD cross-sections is used to confirm the pico-meter- mega-second reactions of cold fusion. Other theoretical aspects are given from measured heavy element distributions similar to the standard abundance distribution, SAD, in the Universe with consequences on endothermic heavy nuclei generation, magic numbers and to quark-gluon plasmas. (authors)

Crossed beam study of He+-O2 charge transfer reactions in the collision energy range 0.5-200 eV

International Nuclear Information System (INIS)

Bischof, G.; Linder, F.

1986-01-01

Energy spectra and angular distributions of the O + and O 2 + product ions resulting from the He + -O 2 charge transfer reaction have been measured in the collision energy range 0.5-200 eV using the crossed-beam method. The O 2 + ions represent only a minor fraction of the reaction products (0.2-0.6% over the energy range measured). In the dissociative charge transfer reaction, four main processes are identified leading to O+O + reaction products in different electronic states. Two different mechanisms can be distinguished, each being responsible for two of the observed processes: (i) a long-distance energy-resonant charge transfer process involving the c 4 Σsub(u) - (upsilon'=0) state of O 2 + and (ii) a slightly exothermic charge transfer process via the (III) 2 PIsub(u) state of O 2 + (with the exothermicity depending on the collision energy). Angle-integrated branching ratios and partial cross sections (in absolute units) have been determined. The branching ratios of the individual processes show a pronounced dependence on the collision energy. At low energies, the O + product ions are preferentially formed in the 2 P 0 and 2 D 0 excited states. The angular distributions of the O + product ions show an anisotropic behaviour indicating an orientation-dependent charge transfer probability in the He + -O 2 reaction. (orig.)

Energy-differential cross section measurement for the 51V(n,α)48Sc reaction

International Nuclear Information System (INIS)

Kanno, I.; Meadows, J.W.; Smith, D.L.

1984-07-01

The activation method was used to measure cross sections for the 51 V(n,α) 48 Sc reaction in the threshold region, from 5.515 MeV up to 9.567 MeV. Twenty approximately-monoenergetic cross section values were obtained in this experiment. These data points span the energy region at roughly equal intervals. The experimental resolutions were in the range 0.153 to 0.233 MeV (FWHM). The present differential data cover approx. 50% of the total integral response of this reaction for the standard 235 U thermal-neutron-induced-fission neutron spectrum, and approx. 44% of the corresponding response for the standard 252 Cf spontaneous-fission neutron spectrum. Over the range 7.6 to 9.5 MeV the present experimental cross sections are noticeably larger (e.g., by approx. 50% at approx. 8.6 MeV) than the corresponding values from the ENDF/B-V evaluation. From approx. 6.7 to 7.5 MeV, the present values are somewhat below those of ENDF/B-V. At still lower energies the agreement is reasonably good considering the uncertainties introduced by energy scale definition very near the effective threshold where the cross section varies rapidly with neutron energy. Calculated integral cross sections based in part on the present work agree reasonably well within errors with reported integral results, provided that the reported data are renormalized to conform with recently-accepted values for appropriate standard reactions. 70 references

Use of Helium Production to Screen Glow Discharges for Low Energy Nuclear Reactions (LENR)

Science.gov (United States)

Passell, Thomas O.

2011-03-01

My working hypothesis of the conditions required to observe low energy nuclear reactions (LENR) follows: 1) High fluxes of deuterium atoms through interfaces of grains of metals that readily accommodate movement of hydrogen atoms interstitially is the driving variable that produces the widely observed episodes of excess heat above the total of all input energy. 2) This deuterium atom flux has been most often achieved at high electrochemical current densities on highly deuterium-loaded palladium cathodes but is clearly possible in other experimental arrangements in which the metal is interfacing gaseous deuterium, as in an electrical glow discharge. 3) Since the excess heat episodes must be producing the product(s) of some nuclear fusion reaction(s) screening of options may be easier with measurement of those ``ashes'' than the observance of the excess heat. 4) All but a few of the exothermic fusion reactions known among the first 5 elements produce He-4. Hence helium-4 appearance in an experiment may be the most efficient indicator of some fusion reaction without commitment on which reaction is occurring. This set of hypotheses led me to produce a series of sealed tubes of wire electrodes of metals known to absorb hydrogen and operate them for 100 days at the 1 watt power level using deuterium gas pressures of ~ 100 torr powered by 40 Khz AC power supplies. Observation of helium will be by measurement of helium optical emission lines through the glass envelope surrounding the discharge. The results of the first 18 months of this effort will be described.

Quasielastic reactions

International Nuclear Information System (INIS)

Henning, W.

1979-01-01

Quasielastic reaction studies, because of their capability to microscopically probe nuclear structure, are still of considerable interest in heavy-ion reactions. The recent progress in understanding various aspects of the reaction mechanism make this aim appear closer. The relation between microscopic and macroscopic behavior, as suggested, for example, by the single proton transfer data to individual final states or averaged excitation energy intervals, needs to be explored. It seems particularly useful to extend measurements to higher incident energies, to explore and understand nuclear structure aspects up to the limit of the energy range where they are important

Indirect Study of the 16O+16O Fusion Reaction Toward Stellar Energies by the Trojan Horse Method

Directory of Open Access Journals (Sweden)

Hayakawa S.

2016-01-01

Full Text Available The 16O+16O fusion reaction is important in terms of the explosive oxygen burning process during late evolution stage of massive stars as well as understanding of the mechanism of low-energy heavy-ion fusion reactions. We aim to determine the excitation function for the most major exit channels, α+28Si and p+31P, toward stellar energies indirectly by the Trojan Horse Method via the 16O(20Ne, α28Siα and 16O(20Ne, p31Pα three-body reactions. We report preliminary results involving reaction identification, and determination of the momentum distribution of α-16O intercluster motion in the projectile 20Ne nucleus.

Effect of collision energy and vibrational excitation on endothermic ion-molecule reactions

International Nuclear Information System (INIS)

Turner, T.P.

1984-07-01

This thesis is divided into two major parts. In the first part an experimental study of proton and deuteron transfer in H 2 + + He and HD + + He has been carried out as a function of kinetic and vibrational energy. The data gives evidence that at lower kinetic energies, the spectator stripping mechanism indeed plays an important role when H 2 + or HD + is vibrationally excited. The second half of this thesis examines the relative efficiencies between the excitation of C-C stretching vibration and collision energy on the promotion of the H atom transfer reaction of C 2 H 2 + + H 2 → C 2 H 3 + + H

Measurements of activation reaction rate distributions on a mercury target bombarded with high-energy protons at AGS

International Nuclear Information System (INIS)

Takada, Hiroshi; Kasugai, Yoshimi; Nakashima, Hiroshi; Ikeda, Yujiro; Jerde, Eric; Glasgow, David

2000-02-01

A neutronics experiment was carried out using a thick mercury target at the Alternating Gradient Synchrotron (AGS) facility of Brookhaven National Laboratory in a framework of the ASTE (AGS Spallation Target Experiment) collaboration. Reaction rate distributions around the target were measured by the activation technique at incident proton energies of 1.6, 12 and 24 GeV. Various activation detectors such as the 115 In(n,n') 115m In, 93 Nb(n,2n) 92m Nb, and 209 Bi(n,xn) reactions with threshold energies ranging from 0.3 to 70.5 MeV were employed to obtain the reaction rate data for estimating spallation source neutron characteristics of the mercury target. It was found from the measured 115 In(n,n') 115m In reaction rate distribution that the number of leakage neutrons becomes maximum at about 11 cm from the top of hemisphere of the mercury target for the 1.6-GeV proton incidence and the peak position moves towards forward direction with increase of the incident proton energy. The similar result was observed in the reaction rate distributions of other activation detectors. The experimental procedures and a full set of experimental data in numerical form are summarized in this report. (author)

Low-energy reaction yields for 18O(p,γ) and 18O(α,γ)

International Nuclear Information System (INIS)

Vogelaar, R.B.; Wang, T.R.; Kellogg, S.E.; Kavanagh, R.W.

1990-01-01

Resonance yields, γ-ray branching, and low-energy limits have been measured for 18 O(p,γ) and 18 O(α,γ), for E p α <0.78 MeV, using a 4π array of NaI detectors. The results confirm previous resonance strengths, and set additional constraints on possible low-energy contributions to stellar reaction rates

On the nucleon effective mass role to the high energy proton spallation reactions

Energy Technology Data Exchange (ETDEWEB)

Santos, B.M., E-mail: biank_ce@if.uff.br [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, 24210-346 Niterói, RJ (Brazil); Instituto Militar de Engenharia, Praça General Tibúrcio 80, 22290-270 Rio de Janeiro, RJ (Brazil); Pinheiro, A.R.C. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil); Universidade Federal do Acre, BR 364 km 04, 69920-900 Rio Branco, AC (Brazil); Gonçalves, M. [Comissão Nacional de Energia Nuclear, Rua General Severiano 90, 22290-901 Rio de Janeiro, RJ (Brazil); Duarte, S.B. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil); Cabral, R.G. [Instituto Militar de Engenharia, Praça General Tibúrcio 80, 22290-270 Rio de Janeiro, RJ (Brazil)

2016-04-15

We explore the effect of the nucleon effective mass to the dynamic evolution of the rapid phase of proton–nucleus spallation reactions. The analysis of the relaxation time for the non-equilibrium phase is studied by variations in the effective mass parameter. We determine the final excitation energy of the hot residual nucleus at the end of cascade phase and the de-excitation of the nuclear system is carried out considering the competition of particle evaporation and fission processes. It was shown that the excitation energy depends of the hot compound residual nucleus at the end of the rapid phase on the changing effective mass. The multiplicity of particles was also analyzed in cascade and evaporation phase of the reaction. The use of nucleon effective mass during cascade phase can be considered as an effect of the many-body nuclear interactions not included explicitly in a treatment to the nucleon–nucleon interaction inside the nucleus. This procedure represents a more realistic scenario to obtain the neutron multiplicity generated in this reaction, which is a benchmark for the calculation of the neutronic in the ADS reactors.

Quasi-classical trajectory study of the role of vibrational and translational energy in the Cl(2P) + NH3 reaction.

Science.gov (United States)

Monge-Palacios, M; Corchado, J C; Espinosa-Garcia, J

2012-05-28

A detailed state-to-state dynamics study was performed to analyze the effects of vibrational excitation and translational energy on the dynamics of the Cl((2)P) + NH(3)(v) gas-phase reaction, effects which are connected to such issues as mode selectivity and Polanyi's rules. This reaction evolves along two deep wells in the entry and exit channels. At low and high collision energies quasi-classical trajectory calculations were performed on an analytical potential energy surface previously developed by our group, together with a simplified model surface in which the reactant well is removed to analyze the influence of this well. While at high energy the independent vibrational excitation of all NH(3)(v) modes increases the reactivity by a factor ≈1.1-2.9 with respect to the vibrational ground-state, at low energy the opposite behaviour is found (factor ≈ 0.4-0.9). However, when the simplified model surface is used at low energy the independent vibrational excitation of all NH(3)(v) modes increases the reactivity, showing that the behaviour at low energies is a direct consequence of the existence of the reactant well. Moreover, we find that this reaction exhibits negligible mode selectivity, first because the independent excitation of the N-H symmetric and asymmetric stretch modes, which lie within 200 cm(-1) of each other, leads to reactions with similar reaction probabilities, and second because the vibrational excitation of the reactive N-H stretch mode is only partially retained in the products. For this "late transition-state" reaction, we also find that vibrational energy is more effective in driving the reaction than an equivalent amount of energy in translation, consistent with an extension of Polanyi's rules. Finally, we find that the non-reactive events, Cl((2)P)+NH(3)(v) → Cl((2)P) + NH(3)(v'), lead to a great number of populated vibrational states in the NH(3)(v') product, even starting from the NH(3)(v = 0) vibrational ground state at low energies

Nuclear structure and reaction studies at medium energies

International Nuclear Information System (INIS)

Hoffmann, G.W.; Ray, R.L.

1990-10-01

This document constitutes the (1988--1991) technical progress report for the ongoing medium energy physics research program supported by the US Department of Energy through special Research Grant FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF), the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL), and at the Fermi National Accelerator Laboratory (FNAL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics;(2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics

Peripheral heavy-ion induced reactions at intermediate energies 20MeV

International Nuclear Information System (INIS)

Barrette, J.; Berthier, B.; Chavez, E.

1984-03-01

Inclusive energy spectra and angular distributions of projectile like fragments in reactions induced by a 44 MeV/nucleon 40 Ar beam bombarding 27 Al and sup(nat)Ti targets show many of the features of high energy fragmentation. However, several aspects such as energy dissipation and production of fragments heavier than the projectile are reminiscent of a low energy behaviour

Low-energy nuclear reactions resulting as parametric interactions with similarity to K-shell electron capture

Energy Technology Data Exchange (ETDEWEB)

Hora, H. [University of New South Wales, Sydney 2052 (Australia); Miley, G.H. [Fusion Studies Laboratory, University of Illinois, Urbana, lL 61801 (United States); Li, X.Z. [Physics Department, Tsinghua University, Beijing 100084 (China); Kelly, J.C. [School of Physics, Sydney University, Sydney 2006 (Australia); Osman, F. [University of Western Sydney, Penrith-Soutti, NSW 1791 (Australia)

2006-07-01

Since the appeal by Brian Josephson at the meeting of the Nobel Laureates July 2004, it seems to be indicated to summarize the following serious, reproducible and confirmed observations on reactions of protons of deuterons incorporated in host metals such as palladium. Some reflections to Rutherford's discovery of nuclear physics, the Cockcroft Oliphant discovery of anomalous low-energy fusion reactions and the chemist Hahn's discovery of fission had to be included. Using gaseous atmosphere or discharges between palladium targets, rather significant results were seen e.g. from the 'life after death' heat production of such high values per host atom that only nuclear reactions can be involved. This supports the earlier evaluation of neutron generation in fully reversible experiments with gas discharges hinting that a reasonable screening effect - preferably in the swimming electron layer - may lead to reactions at nuclear distances d of pico-meters with reaction probability times U of about mega-seconds similar to the K-shell capture radioactivity. Further electrolytic experiments led to low-energy nuclear reactions (LENR) where the involvement of pollution could be excluded from the appearance of very seldom rare earth elements. A basically new theory for DD cross-sections is used to confirm the pico-meter- mega-second reactions of cold fusion. Other theoretical aspects are given from measured heavy element distributions similar to the standard abundance distribution, SAD, in the Universe with consequences on endothermic heavy nuclei generation, magic numbers and to quark-gluon plasmas. (authors)

Investigation of the 10B(n,t) reaction cross-section in the subthreshold energy region

International Nuclear Information System (INIS)

Kornilov, N.V.; Balitskij, A.V.; Baryba, V.Ya.; Druzhnin, V.I.; Kagalenko, A.B.; Kharitonov, A.K.

1991-01-01

The 10 B(n,t) reaction cross-section has been measured at incident neutron energies of 0.025 eV, 420 KeV and 5 MeV. A detailed description of the experimental technique and the Monte Carlo simulation is given. It was confirmed that the cross-section of this reaction in the subthreshold region is non-zero. The recommended value of the 10 B(n,t) reaction cross-section at thermal is 8.5±2.0 mb. (author). 16 refs, 3 figs

Energy dependence of fusion evaporation-residue cross sections in the 28Si+12C reaction

International Nuclear Information System (INIS)

Vineyard, M.F.; Mateja, J.F.; Beck, C.; Atencio, S.E.; Dennis, L.C.; Frawley, A.D.; Henderson, D.J.; Janssens, R.V.F.; Kemper, K.W.; Kovar, D.G.; Maguire, C.F.; Padalino, S.J.; Prosser, F.W.; Stephans, G.S.F.; Tiede, M.A.; Wilkins, B.D.; Zingarelli, R.A.

1993-01-01

Fusion evaporation-residue cross sections for the 28 Si+ 12 C reaction have been measured in the energy range 18≤E c.m. ≤136 MeV using time-of-flight techniques. Velocity distributions of mass-identified reaction products were used to identify evaporation residues and to determine the complete-fusion cross sections at high energies. The data are in agreement with previously established systematics which indicate an entrance-channel mass-asymmetry dependence of the incomplete-fusion evaporation-residue process. The complete-fusion evaporation-residue cross sections and the deduced critical angular momenta are compared with earlier measurements and the predictions of existing models

Study of the p+{sup 12}C reaction at energies up to 30 MeV

Energy Technology Data Exchange (ETDEWEB)

Harada, Masahide; Yamamoto, A.; Yoshioka, S. [Kyushu Univ., Fukuoka (Japan)] [and others

1998-03-01

Double differential cross sections of charged-particles emitted in the p+{sup 12}C reaction were measured in the energy region from 14 to 26 MeV. The observed continuous components of emitted protons and {alpha}-particles were analyzed by assuming sequential decay of intermediate reaction products and/or simultaneous breakup process. It was found that the three body simultaneous decay, p+{alpha}+{sup 8}Be, and the sequential decay via p+{sup 12}C{sup *}{sub 3-} and {alpha}+{sup 9}B{sub g.s.} are most important in the proton-induced breakup of {sup 12}C for energies up to 30 MeV. (author)

Simulation mechanisms of low energy nuclear reaction using super flow energy external fields

International Nuclear Information System (INIS)

Gareev, F.A.; Zhidkova, I.E.; ); Ratis, Yu.I.

2005-01-01

Full text: The review of possible stimulation mechanisms of the LENR (low energy nuclear reactions) is represented. We have concluded that transamination of nuclei at low energies and excess heat are possible in the framework of the modern physical theory - the universal resonance synchronization principle and based on its different enhancement mechanisms of reaction rates are responsible for these processes. The excitation nd ionization of atom may play role as trigger for LERN. Investigation of this phenomenon requires knowledge of different branches if science: nuclear and atomic physics, chemistry and electrochemistry, condensed matter and solid state physics. The results of this research field can provide a new source of energy, substances and technologies. The puzzle of poor re-productivity of experimental data in due ti the fact LENR occurs in open systems and it is extremely sensitive to parameters of external fields and systems. Classical re-productivity principle should be reconsidered for LENR experiments. Poor re-productivity and unexpected results do not means that the experiment is wrong. Our main conclusion: LENR may be understand in terms of the modern theory without any violation of the basic physics. 2) Weak and electromagnetic interactions may show the strong influence of the surrounding conditions on the nuclear processes. 3) Universal resonance synchronization principle is a key issue to make a bridge between various scales of interactions and it is responsible for self-organization of hierarchical systems independent of substances, fields and interactions. We bring some arguments in favor of the mechanism - order based on order - declared by Schroedinger in fundamental problem of contemporary science. 4) The universal resonance synchronization principle became a fruitful interdisciplinary science of general laws of self-organized processes in different branches of physics because it is consequence of the energy conservation law and resonance

Evolution of direct mechanisms with incident energy from the Coulomb-barrier to relativistic energies. - Two-center effects in nucleon transfer between nuclei. - Signatures of nucleon promotion in heavy ion reactions at barrier energies

International Nuclear Information System (INIS)

Oertzen, W. von; Voit, H.; Imanishi, B.

1988-10-01

This report contains a review article considering the evolution of direct mechanisms with incident energy in heavy ion reactions and two theoretical articles concerning two-center effects in transfer reactions between heavy ions and the nucleon promotion in heavy ion reactions. See hints under the relevant topics. (HSI)

Translational energy of products in the K+CH3COCl --> KCl+CH3CO reaction

Science.gov (United States)

Pauluth, M.; Rotzoll, G.

1984-08-01

Time-of-flight distributions of product KCl from the K+CH3COCl reaction have been measured over limited angular ranges at the collision energies 0.16 and 0.70 eV (cm). A simplified analysis assuming separability of cm angle and velocity yields the products' mean translational energy Ē'T. ĒT is very low for the lower collision energy, but increases with increasing collision energy. This finding is in accord with the photodissociation model of Herschbach, that predicts low repulsive energy release for this system.

Interplay of short-range correlations and nuclear symmetry energy in hard-photon production from heavy-ion reactions at Fermi energies

Science.gov (United States)

Yong, Gao-Chan; Li, Bao-An

2017-12-01

Within an isospin- and momentum-dependent transport model for nuclear reactions at intermediate energies, we investigate the interplay of the nucleon-nucleon short-range correlations (SRCs) and nuclear symmetry energy Esym(ρ ) on hard-photon spectra in collisions of several Ca isotopes on 112Sn and 124Sn targets at a beam energy of 45 MeV/nucleon. It is found that over the whole spectra of hard photons studied, effects of the SRCs overwhelm those owing to the Esym(ρ ) . The energetic photons come mostly from the high-momentum tails (HMTs) of single-nucleon momentum distributions in the target and projectile. Within the neutron-proton dominance model of SRCs based on the consideration that the tensor force acts mostly in the isosinglet and spin-triplet nucleon-nucleon interaction channel, there are equal numbers of neutrons and protons, thus a zero isospin asymmetry in the HMTs. Therefore, experimental measurements of the energetic photons from heavy-ion collisions at Fermi energies have the great potential to help us better understand the nature of SRCs without any appreciable influence by the uncertain Esym(ρ ) . These measurements will be complementary to but also have some advantages over the ongoing and planned experiments using hadronic messengers from reactions induced by high-energy electrons or protons. Because the underlying physics of SRCs and Esym(ρ ) are closely correlated, a better understanding of the SRCs will, in turn, help constrain the nuclear symmetry energy more precisely in a broad density range.

Energy dependence of the reaction rate constants of Ar+, Ar++ and N2+ ions with Cl2

International Nuclear Information System (INIS)

Lukac, P.; Holubcik, L.; Morva, I.; Lindinger, W.

2002-01-01

Dry etching processes using low temperature plasmas in Cl 2 and in Cl 2 -noble gas or nitrogen mixtures are common in the manufacture of semiconductor devices, but their chemical mechanisms are often poorly understood. Results are given for the reaction rate constant measurements of Ar + , Ar ++ , N 2 + ions with chlorine as a function of mean relative kinetic energy. The experiments were performed by using the innsbruck flow drift tube (IFDT) apparatus. Measurements were done at various E/N values, where E is the electric field strength and N the buffer gas density in the drift section. The mean relative kinetic energy KE CM between the ions and the neutral chlorine Cl 2 was calculated using the Wanniers formula. It was found that The N 2 + , Ar + and Ar ++ positive ions react with chlorine Cl 2 very fast and the corresponding reaction rate coefficients depend on the mean relative kinetic energy. For the reaction of Ar - with Cl 2 , its reaction coefficient depends also on the buffer gas. It can imply the enhancement of Cl 2 + ions during etching of Si in the Ar/Cl 2 mixtures. (nevyjel)

Fusion reaction cross-sections using the Wong model within Skyrme energy density based semiclassical extended Thomas Fermi approach

Energy Technology Data Exchange (ETDEWEB)

Kumar, Raj, E-mail: rajkumarfzr@gmail.com [Department of Physics, Panjab University, Chandigarh-160014 (India); School of Physics and Material Science, Thapar University, Patiala-147004 (India); Sharma, Manoj K. [School of Physics and Material Science, Thapar University, Patiala-147004 (India); Gupta, Raj K. [Department of Physics, Panjab University, Chandigarh-160014 (India)

2011-11-15

First, the nuclear proximity potential, obtained by using the semiclassical extended Thomas Fermi (ETF) approach in Skyrme energy density formalism (SEDF), is shown to give more realistic barriers in frozen density approximation, as compared to the sudden approximation. Then, taking advantage of the fact that, in ETF method, different Skyrme forces give different barriers (height, position and curvature), we use the l-summed extended-Wong model of Gupta and collaborators (2009) under frozen densities approximation for calculating the cross-sections, where the Skyrme force is chosen with proper barrier characteristics, not-requiring additional 'barrier modification' effects (lowering or narrowing, etc.), for a best fit to data at sub-barrier energies. The method is applied to capture cross-section data from {sup 48}Ca + {sup 238}U, {sup 244}Pu, and {sup 248}Cm reactions and to fusion-evaporation cross-sections from {sup 58}Ni + {sup 58}Ni, {sup 64}Ni + {sup 64}Ni, and {sup 64}Ni + {sup 100}Mo reactions, with effects of deformations and orientations of nuclei included, wherever required. Interestingly, whereas the capture cross-sections in Ca-induced reactions could be fitted to any force, such as SIII, SV and GSkI, by allowing a small change of couple of units in deduced l{sub max}-values at below-barrier energies, the near-barrier data point of {sup 48}Ca + {sup 248}Cm reaction could not be fitted to l{sub max}-values deduced for below-barrier energies, calling for a check of data. On the other hand, the fusion-evaporation cross-sections in Ni-induced reactions at sub-barrier energies required different Skyrme forces, representing 'modifications of the barrier', for the best fit to data at all incident center-of-mass energies E{sub c.m.}'s, displaying a kind of fusion hindrance at sub-barrier energies. This barrier modification effect is taken into care here by using different Skyrme forces for reactions belonging to different regions of

The energy spectrum of neutrons from 7Li(d,n)8Be reaction at deuteron energy 2.9 MeV

Science.gov (United States)

Mitrofanov, Konstantin V.; Piksaikin, Vladimir M.; Zolotarev, Konstantin I.; Egorov, Andrey S.; Gremyachkin, Dmitrii E.

2017-09-01

The neutron beams generated at the electrostatic accelerators using nuclear reactions T(p,n)3He, D(d,n)3He, 7Li(p,n)7Be, T(d,n)4He, 7Li(d,n)8Be, 9Be(d,n)10B are widely used in neutron physics and in many practical applications. Among these reactions the least studied reactions are 7Li(d,n)8Be and 9Be(d,n)10B. The present work is devoted to the measurement of the neutron spectrum from 7Li(d,n)8Be reaction at 0∘ angle to the deuteron beam axis on the electrostatic accelerator Tandetron (JSC "SSC RF - IPPE") using activation method and a stilbene crystal scintillation detector. The first time ever 7Li(d,n)8Be reaction was measured by activation method. The target was a thick lithium layer on metallic backing. The energy of the incident deuteron was 2.9 MeV. As activation detectors a wide range of nuclear reactions were used: 27Al(n,p)27Mg, 27Al(n,α)24Na, 113In(n,n')113mIn, 115In(n,n')115mIn, 115In(n,γ)116mIn, 58Ni(n,p)58mCo, 58Ni(n,2n)57Ni, 197Au(n,γ)198Au, 197Au(n,2n)196Au, 59Co(n,p)59Fe, 59Co(n,2n)58m+gCo, 59Co (n,g)60Co. Measurement of the induced gamma-activity was carried out using HPGe detector Canberra GX5019 [1]. The up-to-date evaluations of the cross sections for these reactions were used in processing of the data. The program STAYSL was used to unfold the energy spectra. The neutron spectra obtained by activation detectors is consistent with the corresponding data measured by a stilbene crystal scintillation detector within their uncertainties.

The energy spectrum of neutrons from 7Li(d,n8Be reaction at deuteron energy 2.9 MeV

Directory of Open Access Journals (Sweden)

Mitrofanov Konstantin V.

2017-01-01

Full Text Available The neutron beams generated at the electrostatic accelerators using nuclear reactions T(p,n3He, D(d,n3He, 7Li(p,n7Be, T(d,n4He, 7Li(d,n8Be, 9Be(d,n10B are widely used in neutron physics and in many practical applications. Among these reactions the least studied reactions are 7Li(d,n8Be and 9Be(d,n10B. The present work is devoted to the measurement of the neutron spectrum from 7Li(d,n8Be reaction at 0∘ angle to the deuteron beam axis on the electrostatic accelerator Tandetron (JSC “SSC RF – IPPE” using activation method and a stilbene crystal scintillation detector. The first time ever 7Li(d,n8Be reaction was measured by activation method. The target was a thick lithium layer on metallic backing. The energy of the incident deuteron was 2.9 MeV. As activation detectors a wide range of nuclear reactions were used: 27Al(n,p27Mg, 27Al(n,α24Na, 113In(n,n'113mIn, 115In(n,n'115mIn, 115In(n,γ116mIn, 58Ni(n,p58mCo, 58Ni(n,2n57Ni, 197Au(n,γ198Au, 197Au(n,2n196Au, 59Co(n,p59Fe, 59Co(n,2n58m+gCo, 59Co (n,g60Co. Measurement of the induced gamma-activity was carried out using HPGe detector Canberra GX5019 [1]. The up-to-date evaluations of the cross sections for these reactions were used in processing of the data. The program STAYSL was used to unfold the energy spectra. The neutron spectra obtained by activation detectors is consistent with the corresponding data measured by a stilbene crystal scintillation detector within their uncertainties.

Study of the Nuclear Transparency in $\\alpha$ + A Reactions at Energies $\\geq$ 12 GeV/nucleon

CERN Multimedia

2002-01-01

The question about transparency is crucial for heavy ion reaction studies. If the transparency is low at 10-15 GeV per nucleon then very large baryon densities can be achieved in this energy range, maybe enough to produce quark-gluon plasma in U+U collisions. We propose to measure, event by event, pseudo-rapidity and multiplicity distributions of singly charged relativistic particles (@b~$>$~0.7) globally and in selected regions of rapidity as well as multiplicities of recoiling protons (30-400~Me charged nuclear fragments. These studies will explore general features of @a+A reactions at energies @$>$~12~GeV/nucleon. The main goal of the experiment is to measure the transparency of nuclear matter in this energy range. The detector will be nuclear emulsion.

Fusion dynamics of 2020Ne + 20882Pb reaction using static and energy dependent Woods-Saxon potential

International Nuclear Information System (INIS)

Gautam, Manjeet Singh; Kaur, Amandeep; Sharma, Manoj K.

2015-01-01

The present work compares the theoretical predictions based on static Woods-Saxon potential and the EDWSP model along with one dimensional Wong formula. For 20 20 Ne + 208 82 Pb reaction, the theoretical calculations obtained by using static Woods-Saxon potential are substantially smaller than that of experimental data at below barrier energies and explain the fusion data at above barrier energies only. On the other hand, the EDWSP model based calculations adequately describe the observed fusion enhancement of 20 20 Ne + 208 82 Pb reaction in whole range of energy spread across the Coulomb barrier. Furthermore, a wide range of the diffuseness parameter ranging from 0.96 fm to 0.85 fm is required to address the sub-barrier fusion data

Measurements of activation reaction rate distributions on a mercury target bombarded with high-energy protons at AGS

Energy Technology Data Exchange (ETDEWEB)

Takada, Hiroshi; Kasugai, Yoshimi; Nakashima, Hiroshi; Ikeda, Yujiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ino, Takashi; Kawai, Masayoshi [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan); Jerde, Eric; Glasgow, David [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2000-02-01

A neutronics experiment was carried out using a thick mercury target at the Alternating Gradient Synchrotron (AGS) facility of Brookhaven National Laboratory in a framework of the ASTE (AGS Spallation Target Experiment) collaboration. Reaction rate distributions around the target were measured by the activation technique at incident proton energies of 1.6, 12 and 24 GeV. Various activation detectors such as the {sup 115}In(n,n'){sup 115m}In, {sup 93}Nb(n,2n){sup 92m}Nb, and {sup 209}Bi(n,xn) reactions with threshold energies ranging from 0.3 to 70.5 MeV were employed to obtain the reaction rate data for estimating spallation source neutron characteristics of the mercury target. It was found from the measured {sup 115}In(n,n'){sup 115m}In reaction rate distribution that the number of leakage neutrons becomes maximum at about 11 cm from the top of hemisphere of the mercury target for the 1.6-GeV proton incidence and the peak position moves towards forward direction with increase of the incident proton energy. The similar result was observed in the reaction rate distributions of other activation detectors. The experimental procedures and a full set of experimental data in numerical form are summarized in this report. (author)

Semiclassical wave packet treatment of scattering resonances: application to the delta zero-point energy effect in recombination reactions.

Science.gov (United States)

Vetoshkin, Evgeny; Babikov, Dmitri

2007-09-28

For the first time Feshbach-type resonances important in recombination reactions are characterized using the semiclassical wave packet method. This approximation allows us to determine the energies, lifetimes, and wave functions of the resonances and also to observe a very interesting correlation between them. Most important is that this approach permits description of a quantum delta-zero-point energy effect in recombination reactions and reproduces the anomalous rates of ozone formation.

Performance and cost of energy transport and storage systems for dish applications using reversible chemical reactions

Science.gov (United States)

Schredder, J. M.; Fujita, T.

1984-01-01

The use of reversible chemical reactions for energy transport and storage for parabolic dish networks is considered. Performance and cost characteristics are estimated for systems using three reactions (sulfur-trioxide decomposition, steam reforming of methane, and carbon-dioxide reforming of methane). Systems are considered with and without storage, and in several energy-delivery configurations that give different profiles of energy delivered versus temperature. Cost estimates are derived assuming the use of metal components and of advanced ceramics. (The latter reduces the costs by three- to five-fold). The process that led to the selection of the three reactions is described, and the effects of varying temperatures, pressures, and heat exchanger sizes are addressed. A state-of-the-art survey was performed as part of this study. As a result of this survey, it appears that formidable technical risks exist for any attempt to implement the systems analyzed in this study, especially in the area of reactor design and performance. The behavior of all components and complete systems under thermal energy transients is very poorly understood. This study indicates that thermochemical storage systems that store reactants as liquids have efficiencies below 60%, which is in agreement with the findings of earlier investigators.

Investigation of nucleon-induced reactions in the Fermi energy domain within the microscopic DYWAN model

Energy Technology Data Exchange (ETDEWEB)

Sebille, F.; Bonilla, C. [SUBATECH, Universite de Nantes, CNRS/IN2P3, 44 - Nantes (France); Blideanu, V.; Lecolley, J.F. [Laboratoire de Physique Corpusculaire, ENSICAEN, Universite de Caen, IN2P3-CNRS, 14 - Caen (France)

2004-06-01

A microscopic investigation of nucleon-induced reactions is addressed within the DYWAN model, which is based on the projection methods of out of equilibrium statistical physics and on the mathematical theory of wavelets. Due to a strongly compressed representation of the fermionic wave-functions, the numerical simulations of the nucleon transport in target are therefore able to preserve the quantum nature of the colliding system, as well as a least biased many-body information needed to keep track of the cluster formation. A special attention is devoted to the fingerprints of the phase space topology induced by the fluctuations of the self-consistent mean-field. Comparisons be ween theoretical results and experimental data point out that ETDHF type approaches are well suited to describe reaction mechanisms in the Fermi energy domain. The observed sensitivity to physical effects shows that the nucleon-induced reactions provide a valuable probe of the nuclear interaction in this range of energy. (authors)

Heavy-ion reactions at energies near the Coulomb barrier

International Nuclear Information System (INIS)

Satchler, G.R.

1991-01-01

The title covers a very broad area of both experimental and theoretical studies. The common characteristic of heavy-ion collisions at these energies, compared to what is usually seen at higher energies, is the important interplay between different reaction channels or internal degrees of freedom. The couplings between the various channels can result in important multistep contributions to a given channel. These often have to be treated explicitly, for example by solving the appropriate set of coupled equations. In contrast, at higher energies the effects of these couplings frequently can be represented in a simple, average way, as is done when one introduces an imaginary part to the optical potential for elastic scattering. At first, it might be thought that the possible importance of multistep transitions would be a strong disadvantage of working at these energies. However, although the analysis of the data becomes more complicate, the study of these terms and their interferences can be a rich source of information. In particular, it can tell us, indirectly, something about transitions between two excited states. Overviews of some of these phenomena have been presented elsewhere; here I have selected two topics as representative. Even then I cannot go into much detail, so perhaps this paper is best regarded as providing some references as the stating point for a literature search exclamation point

Plutonium characterisation with prompt high energy gamma-rays from (n,gamma) reactions for nuclear warhead dismantlement verification

Energy Technology Data Exchange (ETDEWEB)

Postelt, Frederik; Gerald, Kirchner [Carl Friedrich von Weizsaecker-Centre for Science and Peace Research, Hamburg (Germany)

2015-07-01

Measurements of neutron induced gammas allow the characterisation of fissile material (i.e. plutonium and uranium), despite self- and additional shielding. Most prompt gamma-rays from radiative neutron capture reactions in fissile material have energies between 3 and 6.5 MeV. Such high energy photons have a high penetrability and therefore minimise shielding and self-absorption effects. They are also isotope specific and therefore well suited to determine the isotopic composition of fissile material. As they are non-destructive, their application in dismantlement verification is desirable. Disadvantages are low detector efficiencies at high gamma energies, as well as a high background of gammas which result from induced fission reactions in the fissile material, as well as delayed gammas from both, (n,f) and(n,gamma) reactions. In this talk, simulations of (n,gamma) measurements and their implications are presented. Their potential for characterising fissile material is assessed and open questions are addressed.

Generation and scaling behaviour of high-energy pions in relativistic heavy ion reactions

International Nuclear Information System (INIS)

Riess, F.

1979-12-01

Calculations with the help of a collision approximation as carried out in this study, are certainly linked with many uncertainties. The different forms of pulse distributions and cross sections used cover however such a broad region of possibilities, that even detailed calculations will not give any results essentially deviating from those obtained here. The various assumptions and statements could be relatively easily investigated using the collision approximation. Hence the above-mentioned aim, to pick out the principal information from the statement is achieved. It was shown that taking the two assumptions - nucleon-nucleon collisions only and - consideration of a cluster effect, in both cases the experimental results for a given reaction can be well reproduced as long as one only regards one projectile energy. It is important in the first case that the pulse distribution in the region of 0,5 to 1 GeV/c contains sufficiently large components - a simple Gauss distribution with a 'normal' parameter from nuclean physics is not sufficient here. The cluster statement provides the high-energy pions through the changed kinematics, compared to pure nucleon-nucleon collisions, and through the greater energy provided by a cluster in the reaction. (orig./HSI) [de

Inclusive break-up reactions of 6Li at an incident energy of 26 MeV/nucleon

International Nuclear Information System (INIS)

Shyam, R.; Machner, H.; Neumann, B.; Rebel, H.; Gils, H.J.; Planeta, R.; Buschmann, J.; Klewe-Nebenius, H.; Zagromski, S.

1982-01-01

Inclusive charged particle spectra were measured from nuclear reactions induced by 156 MeV 6 Li on 40 Ca. At forward angles the spectra exhibit broad break-up distributions centered around the energy corresponding to the beam velocity. The double differential cross sections together with previous results for a 208 Pb target were analyzed in the framework of the DWBA approach to projectile break-up taking into account elastic and inelastic reactions of the break-up fragments. The high energy tails of the background due to preequilibrium emission of complex charged particles were estimated on the basis of the coalescence model. (orig.) [de

Inclusive break-up reactions of 6Li at an incident energy of 26 MeV/nucleon

International Nuclear Information System (INIS)

Neumann, B.; Rebel, H.; Gils, H.J.; Planeta, R.; Buschmann, J.; Klewe-Nebenius, H.; Zagromski, S.; Shyam, R.; Machner, H.

1982-01-01

Inclusive charged particle spectra were measured from nuclear reactions induced by 156 MeV 6 Li on 40 Ca. At forward angles the spectra exhibit broad break-up distributions centered around the energy corresponding to the beam velocity. The double differential cross sections together with previous results for a 208 Pb target were analyzed in the framework of the DWBA approach to projectile break-up taking into account elastic and inelastic reactions of the break-up fragments. The high energy tails of the background due to preequilibrium emission of complex charged particles were estimated on the basis of the coalescence model. (orig.)

The 14N(p, γ)15O reaction studied at low and high beam energy

International Nuclear Information System (INIS)

Marta, Michele

2012-01-01

The Bethe-Weizsaecker cycle consists of a set of nuclear reactions that convert hydrogen into helium and release energy in the stars. It determines the luminosity of low-metal stars at their turn-off from the main-sequence in the Hertzsprung-Russel diagram, so its rate enters the calculation of the globular clusters' age, an independent lower limit on the age of the universe. The cycle contributes less than 1% to our Sun's luminosity, but it produces neutrinos that can in principle be measured on Earth in underground experiments and bring direct information of the physical conditions in the solar core, provided that the nuclear reaction rate is known with sufficient precision. The 14 N(p,γ) 15 O reaction is the slowest reaction of the Bethe-Weizsaecker cycle and establishes its rate. Its cross section is the sum of the contributions by capture to different excited levels and to the ground state in 15 O. Recent experiments studied the region of the resonance at E p = 278 keV. Only one modern data set from an experiment performed in 1987 is available for the high-energy domain. Both energy ranges are needed to constrain the fit of the excitation function in the R-matrix framework and to obtain a reliable extrapolated S-factor at the very low astrophysical energies. The present research work studied the 14 N(p,γ) 15 O reaction in the LUNA (Laboratory for Underground Nuclear Astrophysics) underground facility at three proton energies 0.36, 0.38, 0.40MeV, and in Dresden in the energy range E p = 0.6 - 2MeV. In both cases, an intense proton beam was sent on solid titanium nitride sputtered targets, and the prompt photons emitted from the reaction were detected with germanium detectors. At LUNA, a composite germanium detector was used. This enabled a measurement with dramatically reduced summing corrections with respect to previous studies. The cross sections for capture to the ground state and to the excited states at 5181, 6172, and 6792 keV in 15 O have been

Mechanisms of emission of particles charged in 6Li + 6Li and 6Li + 10B reactions at low energies

International Nuclear Information System (INIS)

Quebert, Jean

1964-01-01

The lithium 6 nucleus is a projectile of interest to study nuclear reactions at low energy due to the possibility to obtain high heats of reaction, and to its structure which can play an important role in the projectile-target interaction. This research thesis focused on the study of two low-energy reactions provoked by lithium projectiles. These reactions are studied within the framework of the theoretical model of aggregates. The first part presents the experimental conditions of both reactions, reports the development and analysis of nuclear plates, and the transformation of a given type of particle histogram into a spectrum in the mass centre system. The next parts report the study of the 6 Li + 6 Li reaction (previous results, kinematic analysis, spectrum of secondary particles, theoretical analysis of results) and of the 6 Li + 10 B reaction (previous results, experimental results, study of the continuous spectrum of alpha particle, reaction mechanisms)

Neutron Energy Spectra and Yields from the 7Li(p,n) Reaction for Nuclear Astrophysics

Science.gov (United States)

Tessler, M.; Friedman, M.; Schmidt, S.; Shor, A.; Berkovits, D.; Cohen, D.; Feinberg, G.; Fiebiger, S.; Krása, A.; Paul, M.; Plag, R.; Plompen, A.; Reifarth, R.

2016-01-01

Neutrons produced by the 7Li(p, n)7Be reaction close to threshold are widely used to measure the cross section of s-process nucleosynthesis reactions. While experiments have been performed so far with Van de Graaff accelerators, the use of RF accelerators with higher intensities is planned to enable investigations on radioactive isotopes. In parallel, high-power Li targets for the production of high-intensity neutrons at stellar energies are developed at Goethe University (Frankfurt, Germany) and SARAF (Soreq NRC, Israel). However, such setups pose severe challenges for the measurement of the proton beam intensity or the neutron fluence. In order to develop appropriate methods, we studied in detail the neutron energy distribution and intensity produced by the thick-target 7Li(p,n)7Be reaction and compared them to state-of- the-art simulation codes. Measurements were performed with the bunched and chopped proton beam at the Van de Graaff facility of the Institute for Reference Materials and Measurements (IRMM) using the time-of-flight (TOF) technique with thin (1/8") and thick (1") detectors. The importance of detailed simulations of the detector structure and geometry for the conversion of TOF to a neutron energy is stressed. The measured neutron spectra are consistent with those previously reported and agree well with Monte Carlo simulations that include experimentally determined 7Li(p,n) cross sections, two-body kinematics and proton energy loss in the Li-target.

The Atmospherically Important Reaction of Hydroxyl Radicals with Methyl Nitrate: A Theoretical Study Involving the Calculation of Reaction Mechanisms, Enthalpies, Activation Energies, and Rate Coefficients.

Science.gov (United States)

Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M

2017-09-07

A theoretical study, involving the calculation of reaction enthalpies, activation energies, mechanisms, and rate coefficients, was made of the reaction of hydroxyl radicals with methyl nitrate, an important process for methyl nitrate removal in the earth's atmosphere. Four reaction channels were considered: formation of H 2 O + CH 2 ONO 2 , CH 3 OOH + NO 2 , CH 3 OH + NO 3 , and CH 3 O + HNO 3 . For all channels, geometry optimization and frequency calculations were performed at the M06-2X/6-31+G** level, while relative energies were improved at the UCCSD(T*)-F12/CBS level. The major channel is found to be the H abstraction channel, to give the products H 2 O + CH 2 ONO 2 . The reaction enthalpy (ΔH 298 K RX ) of this channel is computed as -17.90 kcal mol -1 . Although the other reaction channels are also exothermic, their reaction barriers are high (>24 kcal mol -1 ), and therefore these reactions do not contribute to the overall rate coefficient in the temperature range considered (200-400 K). Pathways via three transition states were identified for the H abstraction channel. Rate coefficients were calculated for these pathways at various levels of variational transition state theory including tunneling. The results obtained are used to distinguish between two sets of experimental rate coefficients, measured in the temperature range of 200-400 K, one of which is approximately an order of magnitude greater than the other. This comparison, as well as the temperature dependence of the computed rate coefficients, shows that the lower experimental values are favored. The implications of the results to atmospheric chemistry are discussed.

Low-energy d+d fusion reactions via the Trojan Horse Method

Energy Technology Data Exchange (ETDEWEB)

Tumino, A., E-mail: tumino@lns.infn.it [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Universita degli Studi di Enna ' Kore' , Enna (Italy); Spitaleri, C. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mukhamedzhanov, A.M. [Cyclotron Institute Texas A and M University, College Station, TX (United States); Typel, S. [Excellence Cluster Universe, Technische Universitaet Muenchen, Garching (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH - Theorie, Darmstadt (Germany); Aliotta, M. [School of Physics and Astronomy, University of Edinburgh, Edinburgh, Scotland (United Kingdom); Scottish Universities Physics Alliance (United Kingdom); Burjan, V. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Gimenez del Santo, M. [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Kiss, G.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); ATOMKI, Debrecen (Hungary); Kroha, V.; Hons, Z. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); La Cognata, M.; Lamia, L. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mrazek, J. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Pizzone, R.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Piskor, S. [Nuclear Physics Institute of ASCR, Rez (Czech Republic); Rapisarda, G.G.; Romano, S.; Sergi, M.L.; Sparta, R. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy)

2011-06-06

The bare nucleus S(E) factors for the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions have been measured for the first time via the Trojan Horse Method off the proton in {sup 3}He from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre-Main-Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

Low-energy d+d fusion reactions via the Trojan Horse Method

International Nuclear Information System (INIS)

Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A.M.; Typel, S.; Aliotta, M.; Burjan, V.; Gimenez del Santo, M.; Kiss, G.G.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Mrazek, J.; Pizzone, R.G.; Piskor, S.; Rapisarda, G.G.; Romano, S.; Sergi, M.L.; Sparta, R.

2011-01-01

The bare nucleus S(E) factors for the 2 H(d,p) 3 H and 2 H(d,n) 3 He reactions have been measured for the first time via the Trojan Horse Method off the proton in 3 He from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre-Main-Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from available direct data with new S(0) values of 57.4±1.8 MeVb for 3 H+p and 60.1±1.9 MeVb for 3 He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

The (γ, p) reaction in 30Si, 68Zn and 130Te at intermediate energies

International Nuclear Information System (INIS)

Bulow, B.; Johnsson, B.; Nilsson, M.

1977-01-01

The yields of (γ, p) reactions on 30 Si, 68 Zn and 130 Te have been measured as a function of the bremsstrahlung end-point energy, Esub(γ, max), in the energy range 75-800 MeV, using the activation method. Cross sections have been deduced and are compared to results obtained using a semiempirical model. (Auth.)

Tunable Reaction Potentials in Open Framework Nanoparticle Battery Electrodes for Grid-Scale Energy Storage

KAUST Repository

Wessells, Colin D.

2012-02-28

The electrical energy grid has a growing need for energy storage to address short-term transients, frequency regulation, and load leveling. Though electrochemical energy storage devices such as batteries offer an attractive solution, current commercial battery technology cannot provide adequate power, and cycle life, and energy efficiency at a sufficiently low cost. Copper hexacyanoferrate and nickel hexacyanoferrate, two open framework materials with the Prussian Blue structure, were recently shown to offer ultralong cycle life and high-rate performance when operated as battery electrodes in safe, inexpensive aqueous sodium ion and potassium ion electrolytes. In this report, we demonstrate that the reaction potential of copper-nickel alloy hexacyanoferrate nanoparticles may be tuned by controlling the ratio of copper to nickel in these materials. X-ray diffraction, TEM energy dispersive X-ray spectroscopy, and galvanostatic electrochemical cycling of copper-nickel hexacyanoferrate reveal that copper and nickel form a fully miscible solution at particular sites in the framework without perturbing the structure. This allows copper-nickel hexacyanoferrate to reversibly intercalate sodium and potassium ions for over 2000 cycles with capacity retentions of 100% and 91%, respectively. The ability to precisely tune the reaction potential of copper-nickel hexacyanoferrate without sacrificing cycle life will allow the development of full cells that utilize the entire electrochemical stability window of aqueous sodium and potassium ion electrolytes. © 2012 American Chemical Society.

Multifragmentation in intermediate energy ¹²⁹Xe-induced heavy-ion reactions

Energy Technology Data Exchange (ETDEWEB)

Tso, Kin [Univ. of California, Berkeley, CA (United States)

1996-05-01

The ¹²⁹Xe-induced reactions on ^natCu, ⁸⁹Y, ¹⁶⁵Ho, and ¹⁹⁷Au at bombarding energies of E/A = 40 & 60 MeV have been studied theoretically and experimentally in order to establish the underlying mechanism of multifragmentation at intermediate energy heavy-Ion collisions. Nuclear disks formed in central heavy-ion collisions, as simulated by means of Boltzmann-like kinetic equations, break up into several fragments due to a new kind of Rayleigh-like surface instability. A sheet of liquid, stable in the limit of non-interacting surfaces, is shown to become unstable due to surface-surface interactions. The onset of this instability is determined analytically. A thin bubble behaves like a sheet and is susceptible to the surface instability through the crispation mode. The Coulomb effects associated with the depletion of charges in the central cavity of nuclear bubbles are investigated. The onset of Coulomb instability is demonstrated for perturbations of the radial mode. Experimental intermediate-mass-fragment multiplicity distributions for the ¹²⁹Xe-induced reactions are shown to be binomial at each transverse energy. From these distributions, independent of the specific target, an elementary binary decay probability p can be extracted that has a thermal dependence. Thus it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with transverse energy implies a contraction of the emission time scale. The sensitivity of p to the lower Z threshold in the definition of intermediate-mass-fragments points to a physical Poisson simulations of the particle multiplicities show that the weak auto-correlation between the fragment multiplicity and the transverse energy does not distort a Poisson distribution into a binomial distribution. The effect of device efficiency on the experimental results has also been studied.

Hybrid Quantum Mechanics/Molecular Mechanics Solvation Scheme for Computing Free Energies of Reactions at Metal-Water Interfaces.

Science.gov (United States)

Faheem, Muhammad; Heyden, Andreas

2014-08-12

We report the development of a quantum mechanics/molecular mechanics free energy perturbation (QM/MM-FEP) method for modeling chemical reactions at metal-water interfaces. This novel solvation scheme combines planewave density function theory (DFT), periodic electrostatic embedded cluster method (PEECM) calculations using Gaussian-type orbitals, and classical molecular dynamics (MD) simulations to obtain a free energy description of a complex metal-water system. We derive a potential of mean force (PMF) of the reaction system within the QM/MM framework. A fixed-size, finite ensemble of MM conformations is used to permit precise evaluation of the PMF of QM coordinates and its gradient defined within this ensemble. Local conformations of adsorbed reaction moieties are optimized using sequential MD-sampling and QM-optimization steps. An approximate reaction coordinate is constructed using a number of interpolated states and the free energy difference between adjacent states is calculated using the QM/MM-FEP method. By avoiding on-the-fly QM calculations and by circumventing the challenges associated with statistical averaging during MD sampling, a computational speedup of multiple orders of magnitude is realized. The method is systematically validated against the results of ab initio QM calculations and demonstrated for C-C cleavage in double-dehydrogenated ethylene glycol on a Pt (111) model surface.

Fragment formation in GeV-energy proton and light heavy-ion induced reactions

International Nuclear Information System (INIS)

Murakami, T.; Haga, M.; Haseno, M.

2002-01-01

We have investigated similarities and differences among the fragment formation processes in GeV-energy light-ion and light heavy-ion induced reactions. We have newly measured inclusive and exclusive energy spectra of intermediate mass fragments (3 ≤ Z ≤ 30; IMFs) for 8-GeV 16 O and 20 Ne and 12-GeV 20 Ne induced target multifragmentations (TMFs) in order to compare them with those previously measured for 8- and 12-GeV proton induced TMFs. We fond noticeable difference in their spectrum shapes and magnitudes but all of them clearly indicate the existence of sideward-peaked components, indicating fragment formations are mainly dictated not by a incident energy per nucleon but by a total energy of the projectile. (author)

I. Activation energies for the gas phase reactions of hydrogen atom with carbon monoxide and with ethylene. II. Rate constants for the reactions of benzyl cation with triethylphosphine and with triethylarsine in 1,2-dichloroethane

International Nuclear Information System (INIS)

Wang, H.Y.

1976-01-01

Two H-atom reactions H + CO + H 2 → HCO + H 2 and H + C 2 H 4 → C 2 H 5 * were separately studied from room temperature to about 100 0 C, and the activation energies for these two reactions were determined in this temperature range. For H + C 2 H 4 system, a small activation energy of 0.2 kcal/mole was obtained in the present narrow temperature range. The low activation energy indicates that the pre-exponential factor has a predominant contribution to the rate constant of this reaction and has about the same magnitude as that of the rate constant. For H + CO system, a fairly large activation energy of more than 7 kcal/mole was speculated in the potential energy surfaces of the system. The activation energy obtained in the present work, however, has a low value of about 2 kcal/mole. This low value reveals the low level of crossing of this reaction in the potential energy surface and thus indicates considerable complexity involved in the surface. Carbonium ions can be formed from chosen solutes in pulse-irradiated 1,2-dichloroethane (RCl) solutions. Upon irradiation, the electrons generated from the ionization of the solvent become localized on chloride ions as a result of their reaction with the neutral solvent molecules. The solvent counterion, RCl + , on the other hand, is free to exchange charge with the solute molecule. By choosing appropriate solutes, carbonium ion can be formed through a dissociative ionization process in the exchange. The benzyl cation was formed from its precursor compound dibenzylmercury and its reactions with two nucleophiles, triethylphosphine and triethylarsine, were separately studied. The formation and decay of benzyl cation were observed at 363 nm, the position of the maximum of its absorption band, and the second-order rate constants for the two reactions were determined at room temperature

Water Use for Unconventional Energy Development: How Much, What Kind, and to What Reaction?

Science.gov (United States)

Grubert, E.

2017-12-01

Water resources—access to water, protection of water, and allocation of water in particular—are a major priority for Americans, but water use for the energy sector has not previously been well characterized. Water use and management associated with unconventional energy development is of special interest, in part because it is often new to the locations and contexts where it occurs. This presentation focuses on three major questions about water use for unconventional energy development, drawing on both engineering and anthropological research. First, using results from a recent study of water use for energy in the entire United States, how much water does the US use for unconventional energy resources, and how does that compare with water use for more mature fuel cycles? Second, based on that same study, what kind of water is used for these unconventional energy resource fuel cycles? Specifically, where does the water come from, and what is its quality? Finally, drawing on recent case studies in the US and elsewhere, what has the reaction been to these water uses, and why does that matter? Case studies focused on oil and natural gas resources illustrate societal reactions to issues of both water management, particularly related to induced seismicity associated with produced water injection, and water allocation, particularly related to hydraulic fracturing. Overall, recent work finds that public concern about water used for unconventional energy resources is often better explained by observed or anticipated local impacts and the uncertainty surrounding these impacts than by specifics about quantities, allocation, and management techniques. This work provides both quantitative and qualitative characterization of water management and allocation for unconventional energy development.

Model-independent spectroscopic information and the peripheral direct capture A(a,γ)B reaction at stellar energies

International Nuclear Information System (INIS)

Igamov, S.B.; Yarmukhamedov, R.

2004-01-01

Full text: Despite the impressive progress in our understanding of these processes has been made in the last decades, there are still many problems connected with obtaining precise data on the A(p,γ )B and A(α,γ )B reactions cross sections at stellar energies to be solved. One of the possibilities of solving these problems is based on the principally peripheral character of charged particles interaction at low energy and the possibility of using the information on asymptotic normalization coefficients (ANC) (or respective nuclear vertex constants (NVC) for the virtual decay B→A+a ) of the overlap functions for the A(p,γ )B and A(α,γ)B reactions. This review is devoted to critical analysis of traditional methods of obtaining ANC information from DWBA - method calculation of proton transfer reactions and two - body potential model calculation of the direct capture reactions. Moreover in this review modified two - body potential approach allowing to determine both the ANC for virtual decays B→p+A and B→α+A and astrophysical S-factor, S(E), for the A(p,γ)B and A(α,γ)B at stellar energies E (∼ 25 keV) is discussed. This method involves two additional conditions that allow to verify the peripheral character of the considered reactions. New information about rates of t( α ,γ ) 7 Li, 3 He(α ,γ ) 7 Be, 7 Be(p,γ ) 8 B and 12 C(p,γ ) 13 N reactions and estimation of the values of the ANC's for 7 Li →α+t, 7 Be→α+ 3 He, and 8 B→ 7 Be+p has also been presented

Tunneling and reflection in unimolecular reaction kinetic energy release distributions

Science.gov (United States)

Hansen, K.

2018-02-01

The kinetic energy release distributions in unimolecular reactions is calculated with detailed balance theory, taking into account the tunneling and the reflection coefficient in three different types of transition states; (i) a saddle point corresponding to a standard RRKM-type theory, (ii) an attachment Langevin cross section, and (iii) an absorbing sphere potential at short range, without long range interactions. Corrections are significant in the one dimensional saddle point states. Very light and lightly bound absorbing systems will show measurable effects in decays from the absorbing sphere, whereas the Langevin cross section is essentially unchanged.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1979-February 14, 1980

Energy Technology Data Exchange (ETDEWEB)

Rack, E.P.

1980-02-01

The program consists of six interrelated areas: (1) Reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure, and liquid systems. Special attention was given to the reactivity of excited complex formation and structural effects of electrophilic iodine attack on various pi-bond systems. (2) The gas-to-condensed phase transition in halogen high energy chemistry. Current interest involves the study of caging effects of an ice lattice on recombination reactions involving neutron-irradiated frozen aqueous solutions of halogenated organic and biochemical solutes in order to learn more about kinetic energy effects, halogen size, solute molecule size, steric effects and hydrogen bonding within an ice lattice cage. (3) Systematics of halogen hot atom reactions. The reactions of /sup 80m/Br, /sup 80/Br, /sup 82m/Br + /sup 82/Br, /sup 82/Br, /sup 82/Br, /sup 128/I, /sup 130/I, and /sup 130m/I + /sup 130/I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators are currently being studied. (4) Mathematical and computer simulation studies of caging events within an ice lattice are being investigated. (5) At Brookhaven National Laboratory, cyclotron-produced chlorine and fluorine hot atoms substitution reactions with molecules possessing a single chiral center are under investigation to determine the role of hot atom kinetic energy, halogen atom, enantioner structure, steric effects and phase on the extent of substitution by retention of configuration or by Walden inversion. (6) The applications of high energy techniques and concepts to neutron activation analysis for trace element determinations in biological systems was continued.

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

Science.gov (United States)

Gatu Johnson, M.

2017-10-01

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

Multiple scattering theory and applications for intermediate energy reactions of nuclei

International Nuclear Information System (INIS)

Ludeking, L.D.

1979-01-01

Interactions of two composite clusters are treated in a multiple scattering framework whereby many-particle operators are decomposed into a systematic and finite series such that there is an ordered sequestering according to particle rank. Thus, an N-body operator is written as the superposition of all distinct groupings of interactions that occur between particle pairs, triplets, quartets, etc., such that all groupings contain at least one particle from each of the composite systems. It is demonstrated how the transition operator, a reaction operator, and an optical potential may be described in this context. The general structure of such decompositions is shown, and the connection to the standard multiple-scattering prescriptions, delineated. The direct reaction amplitude for stripping and pickup is described, and the two potential formula of Gell-Mann and Goldberger is derived. The multiple scattering formalism for direct reactions is constructed in the eikonal approximation. The sensitivity of the transition cross section to the target density and nucleon-nucleon density correlations are examined in this framework. The limitations of the zero-range approximation to the deuteron vertex function are examined by comparison with the finite-range vertex function at a range of energies. 25 figures, 5 tables

From Cycling Between Coupled Reactions to the Cross-Bridge Cycle: Mechanical Power Output as an Integral Part of Energy Metabolism

Directory of Open Access Journals (Sweden)

Frank Diederichs

2012-10-01

Full Text Available ATP delivery and its usage are achieved by cycling of respective intermediates through interconnected coupled reactions. At steady state, cycling between coupled reactions always occurs at zero resistance of the whole cycle without dissipation of free energy. The cross-bridge cycle can also be described by a system of coupled reactions: one energising reaction, which energises myosin heads by coupled ATP splitting, and one de-energising reaction, which transduces free energy from myosin heads to coupled actin movement. The whole cycle of myosin heads via cross-bridge formation and dissociation proceeds at zero resistance. Dissipation of free energy from coupled reactions occurs whenever the input potential overcomes the counteracting output potential. In addition, dissipation is produced by uncoupling. This is brought about by a load dependent shortening of the cross-bridge stroke to zero, which allows isometric force generation without mechanical power output. The occurrence of maximal efficiency is caused by uncoupling. Under coupled conditions, Hill’s equation (velocity as a function of load is fulfilled. In addition, force and shortening velocity both depend on [Ca2+]. Muscular fatigue is triggered when ATP consumption overcomes ATP delivery. As a result, the substrate of the cycle, [MgATP2−], is reduced. This leads to a switch off of cycling and ATP consumption, so that a recovery of [ATP] is possible. In this way a potentially harmful, persistent low energy state of the cell can be avoided.

Low energy p-Be nuclear reactions for depth-profiling Be in alloys

International Nuclear Information System (INIS)

Pronko, P.P.; Okamoto, P.R.; Weidersich, H.

1977-01-01

Beryllium distributions within the first micron of the surface of nickel- or copper-based alloys were investigated with a 300-keV proton probe utilizing low energy nuclear reactions. Be was segregated in Ni by point defect flows to the surface of the specimen during Ni-ion bombardment of elevated temperatures. The nuclear reactions used are 9 Be(p,d) 8 Be and 9 Be(p,α) 6 Li. The deuteron and alpha groups are simultaneously observable using a standard surface barrier detector. Observations were made at a 150 0 scattering angle; a 2.5 μ mylar filter in front of the detector was used for observing the deuteron yields. The alpha group may be observed with or without the filter depending on whether counting statistics or energy resolution are the more important constraints. Significant Be segregation toward the surface was observed in specimens after irradiation at 625 0 C to 23 dpa with 3.2-MeV Ni ions. Concentrations of Be were nearly doubled within 500 A of the surface and a region depleted of Be extended below the surface layer to a depth of about 3000 A. These results are in agreement with predictions

The two-proton halo nucleus {sup 17}Ne studied in high-energy nuclear breakup reactions

Energy Technology Data Exchange (ETDEWEB)

Wamers, Felix [EMMI, GSI, Darmstadt (Germany); FIAS, Frankfurt (Germany); IKP, TU Darmstadt, Darmstadt (Germany); GSI, Darmstadt (Germany); Marganiec, Justyna [IKP, TU Darmstadt, Darmstadt (Germany); EMMI, GSI, Darmstadt (Germany); GSI, Darmstadt (Germany); Aumann, Thomas [IKP, TU Darmstadt, Darmstadt (Germany); GSI, Darmstadt (Germany); Bertulani, Carlos [Texas A and M University-Commerce, Commerce (United States); Chulkov, Leonid [GSI, Darmstadt (Germany); NRC Kurchatov Institute, Moscow (Russian Federation); Heil, Michael; Simon, Haik [GSI, Darmstadt (Germany); Plag, Ralf [GSI, Darmstadt (Germany); Goethe Universitaet, Frankfurt (Germany); Savran, Deniz [EMMI, GSI, Darmstadt (Germany); FIAS, Frankfurt (Germany); Collaboration: R3B-Collaboration

2014-07-01

We report on exclusive measurements of nuclear breakup reactions of highly-energetic (500 MeV) unstable {sup 17}Ne beams impinging on light targets in an experiment at the R{sup 3}B-LAND complete-kinematics reaction setup at GSI. Focusing on the properties of beam-like {sup 15}O-p (={sup 16}F) systems produced in one-proton-removal reactions, we are presenting a comprehensive analysis of the s-/d-wave configuration mixing of the {sup 17}Ne valence-proton pair that is used to quantify its halo-nature. The results include the {sup 15}O-p relative-energy spectrum, {sup 16}F momentum distributions, and their corresponding momentum profile.

Calculations of Excitation Functions of Some Structural Fusion Materials for ( n, t) Reactions up to 50 MeV Energy

Science.gov (United States)

Tel, E.; Durgu, C.; Aktı, N. N.; Okuducu, Ş.

2010-06-01

Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, the working out the systematics of ( n, t) reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. In this study, ( n, t) reactions for some structural fusion materials such as 27Al, 51V, 52Cr, 55Mn, and 56Fe have been investigated. The new calculations on the excitation functions of 27Al( n, t)25Mg, 51V( n, t)49Ti, 52Cr( n, t)50V, 55Mn( n, t)53Cr and 56Fe( n, t)54Mn reactions have been carried out up to 50 MeV incident neutron energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the new evaluated the geometry dependent hybrid model, hybrid model and the cascade exciton model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, we have calculated ( n, t) reaction cross-sections by using new evaluated semi-empirical formulas developed by Tel et al. at 14-15 MeV energy. The calculated results are discussed and compared with the experimental data taken from the literature.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1979-February 14, 1980

International Nuclear Information System (INIS)

Rack, E.P.

1980-02-01

The program consists of six interrelated areas: (1) Reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure, and liquid systems. Special attention was given to the reactivity of excited complex formation and structural effects of electrophilic iodine attack on various pi-bond systems. (2) The gas-to-condensed phase transition in halogen high energy chemistry. Current interest involves the study of caging effects of an ice lattice on recombination reactions involving neutron-irradiated frozen aqueous solutions of halogenated organic and biochemical solutes in order to learn more about kinetic energy effects, halogen size, solute molecule size, steric effects and hydrogen bonding within an ice lattice cage. (3) Systematics of halogen hot atom reactions. The reactions of /sup 80m/Br, 80 Br, /sup 82m/Br + 82 Br, 82 Br, 82 Br, 128 I, 130 I, and /sup 130m/I + 130 I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators are currently being studied. (4) Mathematical and computer simulation studies of caging events within an ice lattice are being investigated. (5) At Brookhaven National Laboratory, cyclotron-produced chlorine and fluorine hot atoms substitution reactions with molecules possessing a single chiral center are under investigation. (6) The applications of high energy techniques and concepts to neutron activation analysis for trace elements and trace molecule determinations in biological systems was continued

Resonance Strength Measurement at Astrophysical Energies: The 17O(p,α14N Reaction Studied via THM

Directory of Open Access Journals (Sweden)

Sergi M.L.

2016-01-01

Full Text Available In recent years, the Trojan Horse Method (THM has been used to investigate the low-energy cross sections of proton-induced reactions on 17O nuclei, overcoming extrapolation procedures and enhancement effects due to electron screening. We will report on the indirect study of the 17O(p,α14N reaction via the Trojan Horse Method by applying the approach developed for extracting the resonance strength of narrow resonance in the ultralow energy region. The mean value of the strengths obtained in the two measurements was calculated and compared with the direct data available in literature.

Low Energy Nuclear Reaction Aircraft- 2013 ARMD Seedling Fund Phase I Project

Science.gov (United States)

Wells, Douglas P.; McDonald, Robert; Campbell, Robbie; Chase, Adam; Daniel, Jason; Darling, Michael; Green, Clayton; MacGregor, Collin; Sudak, Peter; Sykes, Harrison;

Research on high-energy chemical reactions. Annual progress report, August 1, 1974--October 31, 1975

International Nuclear Information System (INIS)

Cross, R.J. Jr.

1975-10-01

Product yields for the reactions T* + c - C 6 D 12 → c - C 6 D 11 T, DT have been measured using a beam of T* formed by charge exchange in the energy range of 25 eV to 100 eV. A computer program was written to calculate the probability of collision vs. energy of a beam of T* moderated by He gas

Hydrogen desorption reactions of Li-N-H hydrogen storage system: Estimation of activation free energy

International Nuclear Information System (INIS)

Matsumoto, Mitsuru; Haga, Tetsuya; Kawai, Yasuaki; Kojima, Yoshitsugu

2007-01-01

The dehydrogenation reactions of the mixtures of lithium amide (LiNH 2 ) and lithium hydride (LiH) were studied under an Ar atmosphere by means of temperature programmed desorption (TPD) technique. The dehydrogenation reaction of the LiNH 2 /LiH mixture was accelerated by addition of 1 mol% Ti(III) species (k = 3.1 x 10 -4 s -1 at 493 K), and prolonged ball-milling time (16 h) further enhanced reaction rate (k = 1.1 x 10 -3 s -1 at 493 K). For the hydrogen desorption reaction of Ti(III) doped samples, the activation energies estimated by Kissinger plot (95 kJ mol -1 ) and Arrhenius plot (110 kJ mol -1 ) were in reasonable agreement. The LiNH 2 /LiH mixture without Ti(III) species, exhibited slower hydrogen desorption process and the kinetic traces deviated from single exponential behavior. The results indicated the Ti(III) additives change the hydrogen desorption reaction mechanism of the LiNH 2 /LiH mixture

Evaporation residue cross sections for the {sup 100}Mo + {sup 116}Cd reaction -- energy dissipation in hot nuclei

Energy Technology Data Exchange (ETDEWEB)

Back, B.B.; Blumenthal, D.J.; Davids, C.N. [and others

1995-08-01

In this experiment we tried to measure the evaporation residue cross section over a wide range of beam energies for the {sup 100}Mo + {sup 116}Cd reaction using the FMA. However, because of longer-than-estimated runs needed at each beam energy, and the difficulty of bending evaporation residues at the higher energies in the FMA, data were taken only at beam energies of E{sub beam} = 460, 490, and 521 MeV, which correspond to excitation energies of E{sub exc} = 62, 78, and 95 MeV, respectively. By comparing to results for the {sup 32}S + {sup 184}W reactions measured recently, we expect to demonstrate a strong entrance channel effect related to the hindrance of complete fusion in near-symmetric heavy systems (a fusion hindrance factor of the order 7-10 is expected on the basis of the Extra-Push Model). The data are being analyzed.

An accurate potential energy surface for the F + H2 → HF + H reaction by the coupled-cluster method

International Nuclear Information System (INIS)

Chen, Jun; Sun, Zhigang; Zhang, Dong H.

2015-01-01

A three dimensional potential energy surface for the F + H 2 → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2) Q ] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H 2 reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface

On the Determination of the 7Be(n, α)4He Reaction Cross Section at BBN Energies

Science.gov (United States)

Lamia, L.; Spitaleri, C.; Bertulani, C. A.; Hou, S. Q.; La Cognata, M.; Pizzone, R. G.; Romano, S.; Sergi, M. L.; Tumino, A.

2017-12-01

7Be destruction channels are currently a matter of study because of their influence on the 7Li cosmological abundances. Here, we determine the cross section of the (n, α) reaction by using Trojan Horse experimental data for the 7Li(p, α)4He reaction and correcting for Coulomb effects. The deduced 7Be(n, α)4He data overlap with the Big Bang nucleosynthesis energies and the deduced reaction rate allows us to evaluate the corresponding cosmological implications.

A new study of {sup 10}B(p,α){sup 7}Be reaction at low energies

Energy Technology Data Exchange (ETDEWEB)

Caciolli, A.; Depalo, R. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); INFN, Sezione di Padova, Padova (Italy); Broggini, C.; Menegazzo, R. [INFN, Sezione di Padova, Padova (Italy); La Cognata, M.; Puglia, S.M.R.; Sergi, M.L. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Lamia, L. [Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Mou, L.; Rigato, V.; Rossi Alvarez, C. [Laboratori Nazionali di Legnaro, INFN, Legnaro (Italy); Romano, S.; Spitaleri, C. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Tumino, A. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Universita degli Studi di Enna ' ' Kore' ' , Facolta di Ingegneria e Architettura, Enna (Italy)

2016-05-15

The {sup 10}B(p,α){sup 7}Be reaction is of great interest since it has many applications in different fields of research such as nuclear astrophysics, nuclear physics, and models of new reactors for clean energy generation. This reaction has been studied at the AN2000 accelerator of the INFN National Laboratories of Legnaro (LNL). The total cross section has been measured in a wide energy range (250-1182 keV) by using the activation method. The decays of the {sup 7}Be nuclei produced by the reaction were measured at the low counting facility of LNL by using two fully shielded high-purity germanium detectors. The present dataset shows a large discrepancy with respect to one of the previous data at the same energies and reduces the total uncertainty to the level of 6%. An R-matrix calculation has been performed on the present data using the parameters from previous Trojan Horse measurements for the 10 and 500 keV resonances. The present data do not lay on the R-matrix fit in one point suggesting the existence of a {sup 11}C level not observed yet. Further nuclear investigations are needed to confirm this hypothesis. (orig.)

Excitation functions of proton induced reactions on {sup nat}Fe in the energy region up to 45 MeV

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwangsoo [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Khandaker, Mayeen Uddin [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Naik, Haladhara [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Radiochemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Kim, Guinyun, E-mail: gnkim@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

2014-03-01

The excitation functions of various reaction products such as {sup 55,56,57}Co, {sup 52}Fe, {sup 52,54}Mn, and {sup 51}Cr in the {sup nat}Fe(p, x) reactions were measured by the stacked-foil activation technique in the energy range between their respective reaction threshold and 45 MeV at the MC-50 cyclotron of the Korean Institute of Radiological and Medical Sciences, Korea. The present experimental data were compared with the existing literature data. It was found that excitation function of {sup 56,57}Co and {sup 51}Cr from the {sup nat}Fe(p, x) reaction are in agreement with the literature data. However, the cross-sections for {sup nat}Fe(p, x){sup 52}Fe reactions are lower and those for {sup nat}Fe(p, x){sup 52}Mn and {sup nat}Fe(p, x){sup 54}Mn reactions are higher than the literature data. The reaction cross-sections of the above mentioned reaction products were also compared with those from the TENDL-2012 library based on the TALYS-1.4 program as a function of proton energy, which was reproduced the trend of the excitation functions of the experimental {sup nat}Fe(p, x) reaction cross-section. The integral yields for thick target of the investigated radionuclides were calculated from the excitation function.

Converged three-dimensional quantum mechanical reaction probabilities for the F + H2 reaction on a potential energy surface with realistic entrance and exit channels and comparisons to results for three other surfaces

Science.gov (United States)

Lynch, Gillian C.; Halvick, Philippe; Zhao, Meishan; Truhlar, Donald G.; Yu, Chin-Hui; Kouri, Donald J.; Schwenke, David W.

1991-01-01

Accurate three-dimensional quantum mechanical reaction probabilities are presented for the reaction F + H2 yields HF + H on the new global potential energy surface 5SEC for total angular momentum J = 0 over a range of translational energies from 0.15 to 4.6 kcal/mol. It is found that the v-prime = 3 HF vibrational product state has a threshold as low as for v-prime = 2.

Analysis of activation energy in Couette-Poiseuille flow of nanofluid in the presence of chemical reaction and convective boundary conditions

Science.gov (United States)

Zeeshan, A.; Shehzad, N.; Ellahi, R.

2018-03-01

The motivation of the current article is to explore the energy activation in MHD radiative Couette-Poiseuille flow nanofluid in horizontal channel with convective boundary conditions. The mathematical model of Buongiorno [1] effectively describes the current flow analysis. Additionally, the impact of chemical reaction is also taken in account. The governing flow equations are simplified with the help of boundary layer approximations. Non-linear coupled equations for momentum, energy and mass transfer are tackled with analytical (HAM) technique. The influence of dimensionless convergence parameter like Brownian motion parameter, radiation parameter, buoyancy ratio parameter, dimensionless activation energy, thermophoresis parameter, temperature difference parameter, dimensionless reaction rate, Schmidt number, Brinkman number, Biot number and convection diffusion parameter on velocity, temperature and concentration profiles are discussed graphically and in tabular form. From the results, it is elaborate that the nanoparticle concentration is directly proportional to the chemical reaction with activation energy and the performance of Brownian motion on nanoparticle concentration gives reverse pattern to that of thermophoresis parameter.

Energy distribution of neutrons from the (n,2n) reaction in 238U

International Nuclear Information System (INIS)

Misulovin, A.

1978-12-01

Energy distribution of the first and second neutrons from (n,2n) scattering event in 238 U was evaluated according to the consistent compound nucleus model recently proposed by Segev. The law for deriving the energy distribution of secondary neutrons from a (n,2n) scattering event, depends on whether the reaction is considered as a simultaneous emission of two neutrons from one compound nucleus, or a successive emission of neutrons from different compound nuclei. Segev has presented a means of calculating the energy distribution assuming the latter model. The laws presented in the ENDF/B data files suggest the former model. The evaluation was based on inelastic level excitation and evaporation data for 238 U and 237 U. Data was retrieved from ENDF/B files. The evaporation data for 237 U was based on (γ,n) reaction 238 U. The inelastic level excitation data for 237 U was evaluated at the Soreq Nuclear Research Centre. It is concluded from the application of Segev's model to 238 U, that the energetic spectrum of secondary neutrons, is harder in the high range of energy than the one predicted by the use of the distribution law presented in ENDF/B data files. The spectrum of secondary (n,2n) neutrons, resulting from the interaction of 14 MeV neutrons in 238 U calculated with Segev's model, is compared with the corresponding spectrum of the LLL library, ENDF/B library and the recent evaluation of BNWL. It is found that the spectrum evaluated by LLL and BNWL is harder than that evaluated with Segev's model

Peripheral collisions in Ar induced reactions between 27 and 44 A.MeV: study of energy dissipation by measuring the correlated neutron multiplicities

International Nuclear Information System (INIS)

Guerreau, D.; Doubre, H.; Galin, J.; Pouthas, J.; Jahnke, U.; Jiang, D.X.; Lott, B.; Jacquet, D.

1988-01-01

A 4 π detector measuring the neutron multiplicities has been used to investigate the energy dissipation during peripheral collisions in Ar induced reactions around the Fermi Energy. Besides the persistance of direct transfer reactions for the most peripheral collisions, there are strong evidences for the occurrence of quite large energy dissipation, a clear signature for the one body friction to still play a major role at these intermediate energies

Efficient Computational Research Protocol to Survey Free Energy Surface for Solution Chemical Reaction in the QM/MM Framework: The FEG-ER Methodology and Its Application to Isomerization Reaction of Glycine in Aqueous Solution.

Science.gov (United States)

Takenaka, Norio; Kitamura, Yukichi; Nagaoka, Masataka

2016-03-03

In solution chemical reaction, we often need to consider a multidimensional free energy (FE) surface (FES) which is analogous to a Born-Oppenheimer potential energy surface. To survey the FES, an efficient computational research protocol is proposed within the QM/MM framework; (i) we first obtain some stable states (or transition states) involved by optimizing their structures on the FES, in a stepwise fashion, finally using the free energy gradient (FEG) method, and then (ii) we directly obtain the FE differences among any arbitrary states on the FES, efficiently by employing the QM/MM method with energy representation (ER), i.e., the QM/MM-ER method. To validate the calculation accuracy and efficiency, we applied the above FEG-ER methodology to a typical isomerization reaction of glycine in aqueous solution, and reproduced quite satisfactorily the experimental value of the reaction FE. Further, it was found that the structural relaxation of the solute in the QM/MM force field is not negligible to estimate correctly the FES. We believe that the present research protocol should become prevailing as one computational strategy and will play promising and important roles in solution chemistry toward solution reaction ergodography.

Direct dynamics trajectory study of the reaction of formaldehyde cation with D2: vibrational and zero-point energy effects on quasiclassical trajectories.

Science.gov (United States)

Liu, Jianbo; Song, Kihyung; Hase, William L; Anderson, Scott L

2005-12-22

Quasiclassical, direct dynamics trajectories have been used to study the reaction of formaldehyde cation with molecular hydrogen, simulating the conditions in an experimental study of H2CO+ vibrational effects on this reaction. Effects of five different H2CO+ modes were probed, and we also examined different approaches to treating zero-point energy in quasiclassical trajectories. The calculated absolute cross-sections are in excellent agreement with experiments, and the results provide insight into the reaction mechanism, product scattering behavior, and energy disposal, and how they vary with impact parameter and reactant state. The reaction is sharply orientation-dependent, even at high collision energies, and both trajectories and experiment find that H2CO+ vibration inhibits reaction. On the other hand, the trajectories do not reproduce the anomalously strong effect of nu2(+) (the CO stretch). The origin of the discrepancy and approaches for minimizing such problems in quasiclassical trajectories are discussed.

Energy dependence of fusion evaporation-residue cross sections in the 28Si+28Si reaction

International Nuclear Information System (INIS)

Vineyard, M.F.; Bauer, J.S.; Gosdin, C.H.; Trotter, R.S.; Kovar, D.G.; Beck, C.; Henderson, D.J.; Janssens, R.V.F.; Wilkins, B.D.; Rosner, G.; Chowdhury, P.; Ikezoe, H.; Kuhn, W.; Kolata, J.J.; Hinnefeld, J.D.; Maguire, C.F.; Mateja, J.F.; Prosser, F.W.; Stephans, G.S.F.

1990-01-01

Velocity distributions of mass-identified evaporation residues produced in the 28 Si+ 28 Si reaction have been measured at bombarding energies of 174, 215, 240, 309, 397, and 452 MeV using time-of-flight techniques. These distributions were used to identify evaporation residues and to separate the complete-fusion and incomplete-fusion components. Angular distributions and total cross sections were extracted at all six bombarding energies. The complete-fusion evaporation-residue cross sections and the deduced critical angular momenta are compared with lower energy data and the predictions of existing models

Calculation of total free energy yield as an alternative approach for predicting the importance of potential chemolithotrophic reactions in geothermal springs.

Science.gov (United States)

Dodsworth, Jeremy A; McDonald, Austin I; Hedlund, Brian P

2012-08-01

To inform hypotheses regarding the relative importance of chemolithotrophic metabolisms in geothermal environments, we calculated free energy yields of 26 chemical reactions potentially supporting chemolithotrophy in two US Great Basin hot springs, taking into account the effects of changing reactant and product activities on the Gibbs free energy as each reaction progressed. Results ranged from 1.2 × 10(-5) to 3.6 J kg(-1) spring water, or 3.7 × 10(-5) to 11.5 J s(-1) based on measured flow rates, with aerobic oxidation of CH(4) or NH4 + giving the highest average yields. Energy yields calculated without constraining pH were similar to those at constant pH except for reactions where H(+) was consumed, which often had significantly lower yields when pH was unconstrained. In contrast to the commonly used normalization of reaction chemical affinities per mole of electrons transferred, reaction energy yields for a given oxidant varied by several orders of magnitude and were more sensitive to differences in the activities of products and reactants. The high energy yield of aerobic ammonia oxidation is consistent with previous observations of significant ammonia oxidation rates and abundant ammonia-oxidizing archaea in sediments of these springs. This approach offers an additional lens through which to view the thermodynamic landscape of geothermal springs. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Calculation for fission decay from heavy ion reactions at intermediate energies

International Nuclear Information System (INIS)

Blaich, T.; Begemann-Blaich, M.; Fowler, M.M.; Wilhelmy, J.B.; Britt, H.C.; Fields, D.J.; Hansen, L.F.; Namboodiri, M.N.; Sangster, T.C.; Fraenkel, Z.

1992-01-01

A detailed deexcitation calculation is presented for target residues resulting from intermediate-energy heavy ion reactions. The model involves an intranuclear cascade, subsequent fast nucleon emission, and final decay by statistical evaporation including fission. Results are compared to data from bombardments with Fe and Nb projectiles on targets of Ta, Au, and Th at 100 MeV/nucleon. The majority of observable features are reproduced with this simple approach, making obvious the need for involving new physical phenomena associated with multifragmentation or other collective dissipation mechanisms

Single-collision studies of hot atom energy transfer and chemical reaction

International Nuclear Information System (INIS)

Valentini, J.J.

1991-01-01

This report discusses research in the collision dynamics of translationally hot atoms, with funding with DOE for the project ''Single-Collision Studies of Hot Atom Energy Transfer and Chemical Reaction,'' Grant Number DE-FG03-85ER13453. The work reported here was done during the period September 9, 1988 through October 31, 1991. During this period this DOE-funded work has been focused on several different efforts: (1) experimental studies of the state-to-state dynamics of the H + RH → H 2 R reactions where RH is CH 4 , C 2 H 6 , or C 3 H 8 , (2) theoretical (quasiclassical trajectory) studies of hot hydrogen atom collision dynamics, (3) the development of photochemical sources of translationally hot molecular free radicals and characterization of the high resolution CARS spectroscopy of molecular free radicals, (4) the implementation of stimulated Raman excitation (SRE) techniques for the preparation of vibrationally state-selected molecular reactants

Eight-dimensional quantum reaction rate calculations for the H+CH4 and H2+CH3 reactions on recent potential energy surfaces.

Science.gov (United States)

Zhou, Yong; Zhang, Dong H

2014-11-21

Eight-dimensional (8D) transition-state wave packet simulations have been performed on two latest potential energy surfaces (PES), the Zhou-Fu-Wang-Collins-Zhang (ZFWCZ) PES [Y. Zhou, B. Fu, C. Wang, M. A. Collins, and D. H. Zhang, J. Chem. Phys. 134, 064323 (2011)] and the Xu-Chen-Zhang (XCZ)-neural networks (NN) PES [X. Xu, J. Chen, and D. H. Zhang, Chin. J. Chem. Phys. 27, 373 (2014)]. Reaction rate constants for both the H+CH4 reaction and the H2+CH3 reaction are calculated. Simulations of the H+CH4 reaction based on the XCZ-NN PES show that the ZFWCZ PES predicts rate constants with reasonable high accuracy for low temperatures while leads to slightly lower results for high temperatures, in line with the distribution of interpolation error associated with the ZFWCZ PES. The 8D H+CH4 rate constants derived on the ZFWCZ PES compare well with full-dimensional 12D results based on the equivalent m-ZFWCZ PES, with a maximum relative difference of no more than 20%. Additionally, very good agreement is shown by comparing the 8D XCZ-NN rate constants with the 12D results obtained on the ZFWCZ-WM PES, after considering the difference in static barrier height between these two PESs. The reaction rate constants calculated for the H2+CH3 reaction are found to be in good consistency with experimental observations.

The reaction 12C + 12C at bombarding energies from 5 to 10 MeV per nucleon

International Nuclear Information System (INIS)

Morsad, A.

1986-01-01

The reaction 12 C + 12 C has been studied for energies ranging from E LAB = 60 to 120 MeV. The excitation functions and angular distributions were obtained for the elastic (0 + , 0 + ) and inelastic (2 + , 0 + ), (2 + , 2 + ) channels as well as for the transfer channels of one and two nucleons. For the transfer reactions, the feeding of the final bound states was very selective. Narrow correlated structures were found in the transfer and especially in the elastic and inelastic channels. In this energy range, there appears to be a transition from surface transparency to interference phenomena. The optical model in its simplest form is unable to describe the elastic scattering at large angles. This has been interpreted as a consequence of the coupling between the elastic and inelastic channels which is particularly strong of these energies. 80 refs [fr

Microdosimetric concepts for indirect radiation reactions

International Nuclear Information System (INIS)

Pohlit, W.

1976-01-01

It is the aim of microdosimetric models to get information about the influence of microscopic energy deposition by radiation on radiation reactions. Two parameters are always of interest: the energy necessary to produce a certain reaction and the volume in which this energy has to be desposited. In the simple case of an aqueous solution with point targets a complete description of radiation reactions in targets with various concentrations can be given. This model takes into consideration the distinct energy deposition on the particle track, diffusion of radicals and a mean energy necessary for a certain reaction at the target. Typical dose effect curves are obtained which allow the determination of all these quantities from experiments. The model has been tested with the oxydation of iron atoms in aqueous solutions and has been applied for more complex targets such as different alcohols and amino acids. The oxygen consumption in these reactions is used as an easy method for continuous measurement of these indirect reactions. It is the aim of such experiments to get enough quantitative microscopic data on indirect radiation reactions that these reactions can also be followed in living cells

Improved Reaction and Activation Energies of [4+2] Cycloadditions, [3+3] Sigmatropic Rearrangements and Electrocyclizations with the Spin-Component-Scaled MP2 Method

NARCIS (Netherlands)

Goumans, T.P.M.; Ehlers, A.W.; Lammertsma, K.; Wuerthwein, E.-U.; Grimme, S.

2004-01-01

A new quantum mechanical scheme to calculate electronic correlation energies, spin-component-scaled MP2, was tested as a tool to predict reaction energies and barriers in computational organic chemistry. Three common pericyclic reactions with known unsatisfactory MP2 descriptions were reinvestigated

Projectile like fragment production in Ar induced reactions around the Fermi energy

International Nuclear Information System (INIS)

Borrel, V.; Gatty, B.; Jacquet, D.; Galin, J.

1986-01-01

The production of projectile like fragments (PLF) has been studied in Ar induced reactions on various targets. It shows very clearly, that besides the predominance of fragmentation for most of the products, the transfer process is still a very strong component for products nearby the projectile. The influence of the target neutron excess on the PLF production is investigated as well as the evolution with incident energy of the characteristics of the different competing processes

Application of evaporation model to the calculation of energy spectrum and angular distribution of recoil nuclei from neutron induced reaction

Energy Technology Data Exchange (ETDEWEB)

Takeda, Y; Sugimoto, M; Sugiyama, K [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1978-12-01

Calculated angular distributions and energy spectra from 14.8 MeV neutron induced (n,2n) reactions based on a simple evaporation model were obtained by means of the Monte Carlo method. It was ascertained that the effects on the spectra of the method of determining the nuclear temperature and the value of the level density parameter are much smaller than those of the reaction Q-value and the nuclear mass. As a check on the calculational procedure, results of similar calculations were compared with the experimental recoil escape efficiency for /sup 27/Al(n,..cap alpha..)/sup 24/Na reaction. Distortions of the energy spectra in thick target materials were also obtained. These results suggest that this model is fully applicable to the calculation of primary knock-on atoms distributions from various nuclear reactions.

Low energy ion-molecule reaction dynamics and chemiionization kinetics: Progress report, February 1, 1985-January 31, 1988

International Nuclear Information System (INIS)

Farrar, J.M.

1988-01-01

The research program at Rochester is devoted to an understanding of the dynamics of elementary gas phase ionic reactions by using the molecular beam methods. We seek to elucidate pathways for energy disposal in elementary reactions, with the goal of using this information to understand the topology of the potential surfaces which govern the reaction, applying the results to ionic channels in combustion systems. We have made significant accomplishments in several distinct areas of research in crossed beam studies of ion-neutral reaction dynamics in the past three years. Our research has focused on the following topics and has resulted in 15 publications and submissions to major journals, with several additional manuscripts in preparation: dynamics of gas phase proton transfer reactions, gas phase carbon and methyl cation chemistry, reactive scattering from double minimum potentials, reactions of highly vibrationally excited ions: NH 3 + + D 2 , and electron and proton transfer reactions of anions. 9 refs

Activation energies as the validity criterion of a model for complex reactions that can be in oscillatory states

Directory of Open Access Journals (Sweden)

Anić S.

2007-01-01

Full Text Available Modeling of any complex reaction system is a difficult task. If the system under examination can be in various oscillatory dynamic states, the apparent activation energies corresponding to different pathways may be of crucial importance for this purpose. In that case the activation energies can be determined by means of the main characteristics of an oscillatory process such as pre-oscillatory period, duration of the oscillatory period, the period from the beginning of the process to the end of the last oscillation, number of oscillations and others. All is illustrated on the Bray-Liebhafsky oscillatory reaction.

An accurate potential energy surface for the F + H{sub 2} → HF + H reaction by the coupled-cluster method

Energy Technology Data Exchange (ETDEWEB)

Chen, Jun; Sun, Zhigang, E-mail: zsun@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn; Zhang, Dong H., E-mail: zsun@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2015-01-14

A three dimensional potential energy surface for the F + H{sub 2} → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2){sub Q}] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H{sub 2} reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface.

[Intermediate energy studies of polarization transfer, polarized deuteron scattering, and (p,π+-) reactions: Rapporteur's report

International Nuclear Information System (INIS)

Moss, J.M.

1985-01-01

An overview of intermediate energy (80 to 1000 MeV) study contributions to the International Polarization Symposium in Osaka, Japan, August 1985 is presented in this report. Contributions fall into three categories: polarization transfer, polarized deuteron scattering and polarized (p,π +- ) reactions

S-factor of 14 N (α, γ)18 F reaction at low-energies

Science.gov (United States)

Khalili, H.

2018-06-01

The astrophysical S-factor of the 14 N (α, γ)18 F reaction has been studied at range of bombarding energy 1-1.30 MeV. The 14 N (α, γ)18 F process is important in low energy astrophysics so that a possible source of energy in massive stars which have spent their hydrogen cycle. Using the Wood-saxon potential model, we have been calculated non resonances the astrophysical S-factors for the E 2 transition and our results for Eα = 0.0 MeV is S ≈ 0.5 MeV.b where from experimental is measured to Eα = 0.0 is S ≈ o . 7 MeV.b (Couch et al., 1971) that in comparison with our data good agreement is achieved for the astrophysical S-factor of this process.

The search for high-energy deuterons in the 3He +3He reaction

International Nuclear Information System (INIS)

Pigeon, R.; Slobodrian, R.J.

1979-01-01

High-energy deuterons have been detected from the 3 He + 3 He reaction with a system sensitive to cross-sections of 0.6 nb sr -1 . Several tests have permitted to evaluate the small contribution of spurious events. The deuterons are kenematically consistent with the reaction 3 He + 3 He→ 2 H + 4 He + e + +ν, but the measured cross-section at 20deg laboratory is too high for a weak-interaction process; (1.3 +- 0.2) nb sr -1 . It might be due to an interaction of intermediate strength causing the decay of pp pairs ( 3 He) into deuterons. Other alternatives and the implications concerning fusion processes and the production of neutrinos in the sun are discussed in the text

Outline of cold nuclear fusion reaction

International Nuclear Information System (INIS)

Tachikawa, Enzo

1991-01-01

In 2010, as the total supply capacity of primary energy, 666 million liter is anticipated under the measures of thorough energy conservation. The development of energy sources along the energy policy based on environment preservation, safety, the quantity of resources and economy is strongly demanded. The nuclear power generation utilizing nuclear fission has been successfully carried out. As the third means of energy production, the basic research and technical development have been actively advanced on the energy production utilizing nuclear fusion reaction. The main object of the nuclear fusion research being advanced now is D-D reaction and D-T reaction. In order to realize low temperature nuclear fusion reaction, muon nuclear fusion has been studied so far. The cold nuclear fusion reaction by the electrolysis of heavy water has been reported in 1989, and its outline is ixplained in this report. The trend of the research on cold nuclear fusion is described. But the possibility of cold nuclear fusion as an energy source is almost denied. (K.I.)

The {sup 14}N(p, {gamma}){sup 15}O reaction studied at low and high beam energy

Energy Technology Data Exchange (ETDEWEB)

Marta, Michele

2012-07-01

The Bethe-Weizsaecker cycle consists of a set of nuclear reactions that convert hydrogen into helium and release energy in the stars. It determines the luminosity of low-metal stars at their turn-off from the main-sequence in the Hertzsprung-Russel diagram, so its rate enters the calculation of the globular clusters' age, an independent lower limit on the age of the universe. The cycle contributes less than 1% to our Sun's luminosity, but it produces neutrinos that can in principle be measured on Earth in underground experiments and bring direct information of the physical conditions in the solar core, provided that the nuclear reaction rate is known with sufficient precision. The {sup 14}N(p,{gamma}){sup 15}O reaction is the slowest reaction of the Bethe-Weizsaecker cycle and establishes its rate. Its cross section is the sum of the contributions by capture to different excited levels and to the ground state in {sup 15}O. Recent experiments studied the region of the resonance at E{sub p} = 278 keV. Only one modern data set from an experiment performed in 1987 is available for the high-energy domain. Both energy ranges are needed to constrain the fit of the excitation function in the R-matrix framework and to obtain a reliable extrapolated S-factor at the very low astrophysical energies. The present research work studied the {sup 14}N(p,{gamma}){sup 15}O reaction in the LUNA (Laboratory for Underground Nuclear Astrophysics) underground facility at three proton energies 0.36, 0.38, 0.40MeV, and in Dresden in the energy range E{sub p} = 0.6 - 2MeV. In both cases, an intense proton beam was sent on solid titanium nitride sputtered targets, and the prompt photons emitted from the reaction were detected with germanium detectors. At LUNA, a composite germanium detector was used. This enabled a measurement with dramatically reduced summing corrections with respect to previous studies. The cross sections for capture to the ground state and to the excited states

Alternative interpretation of low-energy nuclear reaction processes with deuterated metals based on the Bose-Einstein condensation mechanism

International Nuclear Information System (INIS)

Yeong, E. Kim; Passell, Thomas O.

2006-01-01

Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be larger than (D + D) reaction rates by as much as a factor of ∼ 50, implying that (D + Li) reactions may be occurring in addition to the (D + D) reactions. A survey of the existing data from LENR experiments is carried out to check the validity of the theoretical prediction. We conclude that there is compelling experimental evidence which support the theoretical prediction. New experimental tests of the theoretical prediction are suggested. (authors)

Alternative Interpretation of Low-Energy Nuclear Reaction Processes with Deuterated Metals Based on the Bose-Einstein Condensation Mechanism

Science.gov (United States)

Kim, Yeong E.; Passell, Thomas O.

2006-02-01

Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be larger than (D + D) reaction rates by as much as a factor of ~50, implying that (D + Li) reactions may be occuring in addition to the (D + D) reactions. A survey of the existing data from LENR experiments is carried out to check the validity of the theoretical prediction. We conclude that there is compelling experimental evidence which support the theoretical prediction. New experimental tests of the theoretical prediction are suggested.

Alternative interpretation of low-energy nuclear reaction processes with deuterated metals based on the Bose-Einstein condensation mechanism

Energy Technology Data Exchange (ETDEWEB)

Yeong, E. Kim [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Passell, Thomas O. [TOP Consulting, PO Box 336, Palo Alto, CA 94302-0336 (United States)

2006-07-01

Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be larger than (D + D) reaction rates by as much as a factor of {approx} 50, implying that (D + Li) reactions may be occurring in addition to the (D + D) reactions. A survey of the existing data from LENR experiments is carried out to check the validity of the theoretical prediction. We conclude that there is compelling experimental evidence which support the theoretical prediction. New experimental tests of the theoretical prediction are suggested. (authors)

An ab initio potential energy surface for the reaction N+ + H2→ NH+ + H

International Nuclear Information System (INIS)

Gittins, M.A.; Hirst, D.M.

1975-01-01

Preliminary results of ab initio unrestricted Hartree-Fock calculations for the potential energy surface for the reaction N + + H 2 →NH + + H are reported. For the collinear approach of N + to H 2 , the 3 Σ - surface has no activation barrier and has a shallow well (ca.1eV). For perpendicular approach (Csub(2V)symmetry) the 3 B 2 states is of high energy, the 3 A 2 state has a shallow well but as the bond angle increases the 3 B 1 states decreases in energy to become the state of lowest energy. Neither the collinear nor the perpendicular approaches give adiabatic pathways to the deep potential well of 3 B 1 (HNH) + . (auth.)

The fluorine destruction in stars: First experimental study of the 19F(p,α)16O reaction at astrophysical energies

International Nuclear Information System (INIS)

La Cognata, M.; Mukhamedzhanov, A.; Spitaleri, C.; Indelicato, I.; Aliotta, M.; Burjan, V.; Cherubini, S.; Coc, A.; Gulino, M.; Hons, Z.; Kiss, G. G.; Kroha, V.; Lamia, L.; Mrazek, J.; Palmerini, S.; Piskor, S.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.

2012-01-01

The 19 F(p,α) 16 O reaction is an important fluorine destruction channel in the proton-rich outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogendeficient post-AGB star nucleosynthesis. So far, available direct measurements do not reach the energy region of astrophysical interest (E cm ∼ 300 keV), because of the hindrance effect of the Coulomb barrier. The Trojan Horse (TH) method was thus used to access this energy region, by extracting the quasi-free contribution to the 2 H( 19 F,α 16 O)n reaction. The TH measurement of the α 0 channel, which is the dominant one at such energies, shows the presence of resonant structures not observed before that cause an increase of the reaction rate at astrophysical temperatures up to a factor of 1.7, with potential important consequences for stellar nucleosynthesis.

Isobaric yield ratios and the symmetry energy in heavy-ion reactions near the Fermi energy

International Nuclear Information System (INIS)

Huang, M.; Chen, Z.; Kowalski, S.; Ma, Y. G.; Wada, R.; Hagel, K.; Barbui, M.; Bottosso, C.; Materna, T.; Natowitz, J. B.; Qin, L.; Rodrigues, M. R. D.; Sahu, P. K.; Keutgen, T.; Bonasera, A.; Wang, J.

2010-01-01

The relative isobaric yields of fragments produced in a series of heavy-ion-induced multifragmentation reactions have been analyzed in the framework of a modified Fisher model, primarily to determine the ratio of the symmetry energy coefficient to the temperature, a sym /T, as a function of fragment mass A. The extracted values increase from 5 to ∼16 as A increases from 9 to 37. These values have been compared to the results of calculations using the antisymmetrized molecular dynamics (AMD) model together with the statistical decay code gemini. The calculated ratios are in good agreement with those extracted from the experiment. In contrast, the values extracted from the ratios of the primary isobars from the AMD model calculation are ∼4 to 5 and show little variation with A. This observation indicates that the value of the symmetry energy coefficient derived from final fragment observables may be significantly different than the actual value at the time of fragment formation. The experimentally observed pairing effect is also studied within the same simulations. The Coulomb coefficient is also discussed.

Potential energy effects and diffusion in the relaxed components of the reaction 197Au + 40Ar at 288 and 340 MeV bombarding energies

International Nuclear Information System (INIS)

Moretto, L.G.; Galin, J.; Babinet, R.; Fraenkel, Z.; Schmitt, R.; Jared, R.; Thompson, S.G.

1976-01-01

The fragments emitted in the reaction between 197 Au and 40 Ar at 288 and 340 MeV bombarding energies have been studied. The fragments have been identified in atomic number up to Z = 32 by means of an E-ΔE telescope. The kinetic energy distributions, the cross sections and the angular distributions have been measured for each Z. The kinetic energy distributions show the typical quasielastic and relaxed components; the Z-distributions show a smooth increase in the cross section with increasing Z, interrupted at relatively forward angles by a fairly sharp peak close to Z = 18. The angular distributions are forward peaked in excess of 1/sin theta for atomic numbers as large as Z approximately 30, as far as twelve atomic number units above the projectile; this is at variance with other reactions like Ag+ 20 Ne, where the angular distributions become 1/sin(theta) four or five atomic number units above the projectile. This is interpreted in terms of an enhanced diffusion towards symmetry, possibly promoted by the potential energy in the intermediate complex corresponding to two fragments in contact. (Auth.)

Standard Gibbs free energies of reactions of ozone with free radicals in aqueous solution: quantum-chemical calculations.

Science.gov (United States)

Naumov, Sergej; von Sonntag, Clemens

2011-11-01

Free radicals are common intermediates in the chemistry of ozone in aqueous solution. Their reactions with ozone have been probed by calculating the standard Gibbs free energies of such reactions using density functional theory (Jaguar 7.6 program). O(2) reacts fast and irreversibly only with simple carbon-centered radicals. In contrast, ozone also reacts irreversibly with conjugated carbon-centered radicals such as bisallylic (hydroxycylohexadienyl) radicals, with conjugated carbon/oxygen-centered radicals such as phenoxyl radicals, and even with nitrogen- oxygen-, sulfur-, and halogen-centered radicals. In these reactions, further ozone-reactive radicals are generated. Chain reactions may destroy ozone without giving rise to products other than O(2). This may be of importance when ozonation is used in pollution control, and reactions of free radicals with ozone have to be taken into account in modeling such processes.

Mode specificity in the OH + CHD3 reaction: Reduced-dimensional quantum and quasi-classical studies on an ab initio based full-dimensional potential energy surface

International Nuclear Information System (INIS)

Song, Hongwei; Yang, Minghui; Lu, Yunpeng; Li, Jun; Guo, Hua

2016-01-01

An initial state selected time-dependent wave packet method is applied to study the dynamics of the OH + CHD 3 reaction with a six-dimensional model on a newly developed full-dimensional ab initio potential energy surface (PES). This quantum dynamical (QD) study is complemented by full-dimensional quasi-classical trajectory (QCT) calculations on the same PES. The QD results indicate that both translational energy and the excitation of the CH stretching mode significantly promote the reaction while the excitation of the umbrella mode has a negligible effect on the reactivity. For this early barrier reaction, interestingly, the CH stretching mode is more effective than translational energy in promoting the reaction except at very low collision energies. These QD observations are supported by QCT results. The higher efficacy of the CH stretching model in promoting this early barrier reaction is inconsistent with the prediction of the naively extended Polanyi’s rules, but can be rationalized by the recently proposed sudden vector projection model.

On the geometric nature of high energy nucleus-nucleus reaction cross sections

International Nuclear Information System (INIS)

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

1982-01-01

Within the context of a high energy double-folding optical potential approximation to the exact nucleus-nucleus multiple-scattering series, eikonal scattering theory is used to investigate the validity of geometric reaction cross sections in relativistic heavy ion collisions. The potential used includes a finite range interaction and nuclear single-particle densities extracted from nuclear charge distributions by unfolding the proton charge distribution. Pauli correlation effects are also included in an approximate way. The sensitivity of the predictions to be assumed interaction, Pauli correlation approximation, and nuclear density distributions is investigated. These results are in agreement with early predictions concerning the geometric nature of relativistic heavy ion collisions and in disagreement with a recent analysis, utilizing the zero range approximation, which suggested otherwise. Reasons for the lack of agreement between the analyses are also presented. Finally, approximate applicability for geometric reaction cross sections are determined

Investigation of the 14N/d,α/12C reaction at Esub(d)=640-310 keV deuteron energies

International Nuclear Information System (INIS)

Bakr, M.H.S.; Hunyadi, I.; Schlenk, G.; Somogyi, G.; Valek, A.

1974-01-01

Angular distributions of the α 0 , α 1 , α 2 , and α 3 groups from the 14 N/d,α/ 12 C reaction have been measured at deuteron energies 640, 510, and 350 keV using solid state track detectors. Semiconductor detector was used to measure the excitation functions of the α 0 and α 1 groups from the same reaction in the energy range 640-310 keV at THETAsub(lab)=90 0 . The absolute cross-section values are given for the alpha groups investigated. The experimentally obtained angular distributions have been analysed in terms of Legendre polynomials. The measured relative intensity ratios of the α 0 , α 1 , and α 3 groups could be reproduced by a simple calculation assuming statistical compound reaction mechanism. (B.T.)

Reactions induced by low energy electrons in cryogenic films

International Nuclear Information System (INIS)

Bass, A.D.; Sanche, L.

2003-01-01

We review recent research on reactions (including dissociation) initiated by low-energy electron bombardment of monolayer and multilayer molecular solids at cryogenic temperatures. With incident electrons of energies below 20 eV, dissociation is observed by the electron stimulated desorption (ESD) of anions from target films and is attributed to the processes of dissociative electron attachment (DEA) and to dipolar dissociation. It is shown that DEA to condensed molecules is sensitive to environmental factors such as the identity of co-adsorbed species and film morphology. The effects of image-charge induced polarization on cross-sections for DEA to CH3Cl are also discussed. Taking as examples, the electron-induced production of CO within multilayer films of methanol and acetone, it is shown that the detection of electronic excited states by high resolution electron energy loss spectroscopy can be used to monitor electron beam damage. In particular, the incident energy dependence of the CO indicates that below 19 eV, dissociation proceeds via the decay of transient negative ions (TNI) into electronically excited dissociative states. The electron induced dissociation of biomolecular targets is also considered, taking as examples the ribose analog tetrahydrofuran and DNA bases adenine and thymine, cytosine and guanine. The ESD of anions from such films also show dissociation via the formation of TNI. In multilayer molecular solids, fragment species resulting from dissociation, may react with neighboring molecules, as is demonstrated in anion ESD measurements from films containing O 2 and various hydrocarbon molecules. X-ray photoelectron spectroscopy measurements reported for electron irradiated monolayers of H 2 O and CF 4 on a Si - H passivated surface further show that DEA is an important initial step in the electron-induced chemisorption of fragment species

Global control of reaction wheel pendulum through energy regulation and extended linearization of the state variables

Directory of Open Access Journals (Sweden)

Oscar D. Montoya-Giraldo

2014-01-01

Full Text Available This paper presents the design and simulation of a global controller for the Reaction Wheel Pendulum system using energy regulation and extended linearization methods for the state feedback. The proposed energy regulation is based on the gradual reduction of the energy of the system to reach the unstable equilibrium point. The signal input for this task is obtained from the Lyapunov stability theory. The extended state feedback controller design is used to get a smooth nonlinear function that extends the region of operation to a bigger range, in contrast with the static linear state feedback obtained through the method of approximate linearization around an operating point. The general designed controller operates with a switching between the two control signals depending upon the region of operation; perturbations are applied in the control signal and the (simulated measured variables to verify the robustness and efficiency of the controller. Finally, simulations and tests using the model of the reaction wheel pendulum system, allow to observe the versatility and functionality of the proposed controller in the entire operation region of the pendulum.

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas.

Science.gov (United States)

Adamovich, Igor V; Li, Ting; Lempert, Walter R

2015-08-13

This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H2-air and hydrocarbon-air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N(2) vibrational energy transfer, reactions of excited electronic species of N(2), O(2), N and O, and 'conventional' chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N(2) vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H(2)-air, CH(4)-air and C(2)H(4)-air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H2-mixtures, showing good agreement with the data. The model predictions for OH number density in lean C(3)H(8)-air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C(3)H(8)-air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane-n-butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H(2)-air, CH(4)-air and C(2)H(4)-air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane-air mixtures demonstrates the need for development of a more accurate

Isospin splitting of nucleon effective mass and symmetry energy in isotopic nuclear reactions

Science.gov (United States)

Guo, Ya-Fei; Chen, Peng-Hui; Niu, Fei; Zhang, Hong-Fei; Jin, Gen-Ming; Feng, Zhao-Qing

2017-10-01

Within an isospin and momentum dependent transport model, the dynamics of isospin particles (nucleons and light clusters) in Fermi-energy heavy-ion collisions are investigated for constraining the isospin splitting of nucleon effective mass and the symmetry energy at subsaturation densities. The impacts of the isoscalar and isovector parts of the momentum dependent interaction on the emissions of isospin particles are explored, i.e., the mass splittings of and (). The single and double neutron to proton ratios of free nucleons and light particles are thoroughly investigated in the isotopic nuclear reactions of 112Sn+112Sn and 124Sn+124Sn at incident energies of 50 and 120 MeV/nucleon, respectively. It is found that both the effective mass splitting and symmetry energy impact the kinetic energy spectra of the single ratios, in particular at the high energy tail (larger than 20 MeV). The isospin splitting of nucleon effective mass slightly impacts the double ratio spectra at the energy of 50 MeV/nucleon. A soft symmetry energy with stiffness coefficient of γ s=0.5 is constrained from the experimental data with the Fermi-energy heavy-ion collisions. Supported by Major State Basic Research Development Program in China (2014CB845405, 2015CB856903), National Natural Science Foundation of China (11722546, 11675226, 11675066, U1332207) and Youth Innovation Promotion Association of Chinese Academy of Sciences

Background studies of high energy γ rays from (n,γ) reactions in the CANDLES experiment

Science.gov (United States)

Nakajima, K.; Iida, T.; Akutagawa, K.; Batpurev, T.; Chan, W. M.; Dokaku, F.; Fushimi, K.; Kakubata, H.; Kanagawa, K.; Katagiri, S.; Kawasaki, K.; Khai, B. T.; Kino, H.; Kinoshita, E.; Kishimoto, T.; Hazama, R.; Hiraoka, H.; Hiyama, T.; Ishikawa, M.; Li, X.; Maeda, T.; Matsuoka, K.; Moser, M.; Nomachi, M.; Ogawa, I.; Ohata, T.; Sato, H.; Shamoto, K.; Shimada, M.; Shokati, M.; Takahashi, N.; Takemoto, Y.; Takihira, Y.; Tamagawa, Y.; Tozawa, M.; Teranishi, K.; Tetsuno, K.; Trang, V. T. T.; Tsuzuki, M.; Umehara, S.; Wang, W.; Yoshida, S.; Yotsunaga, N.

2018-07-01

High energy γ rays with several MeV produced by (n,γ) reactions can be a trouble for low background measurements in the underground laboratories such as double beta decay experiments. In the CANDLES project, which aimed to observe the neutrino-less double beta decay from 48Ca, γ rays caused by (n,γ) reactions were found to be the most significant background. The profile of the background was studied by measurements with a neutron source and a simulation with a validity check of neutron processes in Geant4. The observed spectrum of γ rays from (n,γ) reactions was well reproduced by the simulated spectra, which were originated from the surrounding rock and a detector tank made of stainless steel. The environmental neutron flux was derived by the observed event rate of γ rays from (n,γ) reactions using the simulation. The thermal and non-thermal neutron flux were found to be (1.3 ± 0.6) ×10-6 cm-2s-1 and (1.1 ± 0.5) ×10-5 cm-2s-1 , respectively. It is necessary to install an additional shield to reduce the background from (n,γ) reaction to the required level.

Smooth transition from sudden to adiabatic states in heavy-ion fusion reactions at deep-subbarrier incident energies

International Nuclear Information System (INIS)

Takatoshi, Ichikawa; Kouichi, Hagino; Akira, Iwamoto

2011-01-01

We propose a novel extension of the standard coupled-channel (CC) model in order to account for the steep falloff of fusion cross sections at deep-subbarrier incident energies. We introduce a damping factor in the coupling potential in the CC model, simulating smooth transitions from sudden to adiabatic states in deep- subbarrier fusion reactions. The CC model extended with the damping factor can reproduce well not only the steep falloff of the fusion cross section but also the saturation of the logarithmic derivatives for the fusion cross sections at deep-subbarrier energies for the 16 O+ 208 Pb, 64 Ni+ 64 Ni, and 58 Ni+ 58 Ni reactions at the deep-subbarrier energies. The important point in our model is that the transition takes place at different places for each Eigen channel. We conclude that the smooth transition from the two-body to the adiabatic one-body potential is responsible for the steep falloff of the fusion cross section

Global phenomenological optical model potential for nucleon-actinide reactions at energies up to 300 MeV

International Nuclear Information System (INIS)

Han Yinlu; Liang Haiying; Guo Hairui; Shen Qingbiao; Xu Yongli

2010-01-01

A set of new global phenomenological optical model potential parameters for the actinide region with incident nucleon energies from 1 keV up to 300 MeV is obtained. They are based on a smooth, unique functional form for the energy dependence of the potential depths and on physically constrained geometry parameters. The available experimental data including the neutron total cross sections, nonelastic cross sections, elastic scattering cross sections, elastic scattering angular distributions, and proton reaction cross sections and elastic scattering angular distributions of 232 Th and 238 U are used. The new nucleon global optical model potential parameters obtained are analyzed and used to analyze the experimental data of nucleon-actinide reactions. It is found that the present form of the global optical model potential could reproduce both the neutron and the proton experimental data.

What we have learned so far on reactions and scattering with weakly bound nuclei at near barrier energies

International Nuclear Information System (INIS)

Gomes, P.R.S.

2011-01-01

Reactions involving weakly bound nuclei, especially halo nuclei, at near barrier energies, are an important subject not yet fully understood. Due to the low threshold energy for breakup, this process is particularly important and may affect significantly the fusion process and elastic scattering. In this talk I will show the systematic of results so far available in this field, concerning static and dynamical effects of halo and breakup on fusion and total reaction cross sections, the energy dependence of the optical potential on the elastic scattering and coupling effects on quasi-elastic scattering barrier distributions involving weakly bound nuclei, both stable and radioactive. The data to be discussed are new data from our group and from the literature, together with some older data. I will also present some experimental challenges for the development of this field. (author)

Basic reactions induced by radiation

International Nuclear Information System (INIS)

Charlesby, A.

1980-01-01

This paper summarises some of the basic reactions resulting from exposure to high energy radiation. In the initial stages energy is absorbed, but not necessarily at random, giving radical and ion species which may then react to promote the final chemical change. However, it is possible to intervene at intermediate stages to modify or reduce the radiation effect. Under certain conditions enhanced reactions are also possible. Several expressions are given to calculate radiation yield in terms of energy absorbed. Some analogies between radiation-induced reactions in polymers, and those studied in radiobiology are outlined. (author)

Investigation of (n, p) and (n, alpha) reactions with thermal and resonance energy neutrons

CERN Document Server

Gledenov, Yu M

2002-01-01

Influence of results of (n, alpha) and (n, p) reactions cross section and asymmetry measurements on certain branches of fundamental and applied science is considered. For instance, some of the cross sections are critical for comprehension of many scenarios of nuclear synthesis in the Universe. They are also used for studying some aspects of nuclear structure and fundamental symmetries, such as mixing of isospin and non-retaining of spatial parity. And, finally, cross sections of the reactions are of applied interest, for reactor materials technologies specifically. Types of sources and methods of (n, p) and (n, alpha) reactions measurements in energy range of thermal and resonance neutrons are described in the review. Special attention is paid to measurements in radioactive relatively short-lived samples and very small stable samples. Several examples of the measurements are provided, which are of scientific interest, as they permit demonstrating the method used. Possible future measurements are discussed in ...

Calculation of neutron monitor reaction cross sections of {sup 90}Zr in energy region up to 100 MeV

Energy Technology Data Exchange (ETDEWEB)

Qingbiao, Shen; Baosheng, Yu; Dunjiu, Cai [Chinese Nuclear Data Center, Beijing, BJ (China)

1996-06-01

Many nuclear data for n + {sup 90}Zr reaction were calculated by using optical model evaporation model and exciton model. The program SPEC, including the first to the sixth particle emission processes, was used in our calculations. The calculated results show that the activation products {sup 89,88}Zr and {sup 88,87}Y are important neutron monitor reaction products for n + {sup 90}Zr reaction in energy range up to 100 MeV. (4 figs.).

Photo-neutron reaction cross-section for 93Nb in the end-point bremsstrahlung energies of 12–16 and 45–70 MeV

International Nuclear Information System (INIS)

Naik, H.; Kim, G.N.; Schwengner, R.; Kim, K.; Zaman, M.; Tatari, M.; Sahid, M.; Yang, S.C.; John, R.; Massarczyk, R.; Junghans, A.; Shin, S.G.; Key, Y.; Wagner, A.; Lee, M.W.; Goswami, A.; Cho, M.-H.

2013-01-01

The photo-neutron cross-sections of 93 Nb at the end-point bremsstrahlung energies of 12, 14 and 16 MeV as well as 45, 50, 55, 60 and 70 MeV have been determined by the activation and the off-line γ-ray spectrometric techniques using the 20 MeV electron linac (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, and 100 MeV electron linac at Pohang Accelerator Laboratory (PAL), Pohang, Korea. The 93 Nb(γ, xn, x=1–4) reaction cross-sections as a function of photon energy were also calculated using computer code TALYS 1.4. The flux-weighted average values were obtained from the experimental and the theoretical (TALYS) values based on mono-energetic photons. The experimental values of present work are in good agreement with the flux-weighted theoretical values of TALYS 1.4 but are slightly higher than the flux-weighted experimental data of mono-energetic photons. It was also found that the theoretical and the experimental values of present work and literature data for the 93 Nb(γ, xn) reaction cross-sections increase from the threshold values to a certain energy, where other reaction channels opens. However, the increase of 93 Nb(γ, n) and 93 Nb(γ, 2n) reaction cross-sections are sharper compared to 93 Nb(γ, 3n) and 93 Nb(γ, 4n) reaction cross-sections. The sharp increase of 93 Nb(γ, n) and 93 Nb(γ, 2n) reaction cross-sections from the threshold value up to 17–22 MeV is due to the Giant Dipole Resonance (GDR) effect besides the role of excitation energy. After a certain values, the individual 93 Nb(γ, xn) reaction cross-sections decrease with increase of bremsstrahlung energy due to opening of other reaction channels

Energy independent partial wave analysis of the reactions π+-p→Nππ between 1.36 and 1.76GeV c.m.s. energy

International Nuclear Information System (INIS)

Dolbeau, J.; Triantis, F.A.; Neveu, M.; Cadiet, F.

1975-01-01

A new partial wave analysis of the three reactions π - p→pπ - π 0 , π - p→nπ + π - , and π + p→pπ + π 0 is presented at nine c.m. energies between 1.36 and 1.76GeV, using about 91300 Nππ events. Within the framework of the generalized isobar model it is possible to describe the data with Δ, rho and sigma(ππ, i=0) production, as well as to reproduce the π - p→nπ 0 π 0 and π + p→nπ + π + cross sections. New prescriptions for the description of sigma and for the centrifugal barrier term are obtained. Furthermore, at the highest energy, there is evidence for N* production and for the presence of a ππ interaction, contributing about 5% to the cross sections of the reaction π - p→pπ - π 0 and π + p→pπ + π 0 . Finally, Argand plots are presented, showing the main inelastic couplings for ten resonances in this energy range [fr

Low Energy Reaction cell for advanced space power applications

International Nuclear Information System (INIS)

Miley, George H.; Rice, Eric

2001-01-01

Power units using Low Energy Reactions (LENRs) are under study as a radical new approach to power units that could potentially replace nuclear and chemical power sources for a number of space applications. These cells employ thin metallic films (order of 500 deg., using variously Ni, Pd and Ti) as cathodes with various electrolytes such as 0.5-1 molar lithium sulfate in light water. Power densities exceeding 10 W/cm3 in the thin-films have been achieved. An ultimate goal is to incorporate this thin-film technology into a 'tightly packed' cell design where the film material occupies ∼20% of the total cell volume. If this is achieved, overall power densities of ∼20 W/cm3 appear feasible, opening the way to a number of potential applications ranging from distributed power units in spacecraft to advanced propulsion

Extended sudden approximation model for high-energy nucleon removal reactions

Energy Technology Data Exchange (ETDEWEB)

Carstoiu, F.; Sauvan, E.; Orr, N.A. [Caen Univ., Lab. de Physique Corpusculaire, Institut des Sciences de la Matiere et du Rayonnement, IN2P3-CNRS ISMRA, 14 (France); Carstoiu, F. [IFIN-HH, Bucharest-Magurele (Romania); Bonaccorso, A. [Istituto Nazionale di Fisica Nucleare, Pisa (Italy)

2004-04-01

A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen, the nucleon-removal cross section and the full 3-dimensional momentum distributions of the core fragments including absorption, diffraction, Coulomb and nuclear-Coulomb interference amplitudes, have been calculated. The Coulomb breakup has been treated to all orders for the dipole interaction. The model has been compared to experimental data for a range of light, neutron-rich psd-shell nuclei. Good agreement was found for both the inclusive cross sections and momentum distributions. In the case of {sup 17}C, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The calculated 3-dimensional momentum distributions exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, whilst no such effect is apparent for d-waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored. (authors)

Extended sudden approximation model for high-energy nucleon removal reactions

International Nuclear Information System (INIS)

Carstoiu, F.; Sauvan, E.; Orr, N.A.; Carstoiu, F.; Bonaccorso, A.

2004-04-01

A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen, the nucleon-removal cross section and the full 3-dimensional momentum distributions of the core fragments including absorption, diffraction, Coulomb and nuclear-Coulomb interference amplitudes, have been calculated. The Coulomb breakup has been treated to all orders for the dipole interaction. The model has been compared to experimental data for a range of light, neutron-rich psd-shell nuclei. Good agreement was found for both the inclusive cross sections and momentum distributions. In the case of 17 C, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The calculated 3-dimensional momentum distributions exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, whilst no such effect is apparent for d-waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored. (authors)

Production of complex particles in low energy spallation and in fragmentation reactions by in-medium random clusterization

International Nuclear Information System (INIS)

Lacroix, D.; Durand, D.

2005-09-01

Rules for in-medium complex particle production in nuclear reactions are proposed. These rules have been implemented in two models to simulate nucleon-nucleus and nucleus-nucleus reactions around the Fermi energy. Our work emphasizes the effect of randomness in cluster formation, the importance of the nucleonic Fermi motion as well as the role of conservation laws. The concepts of total available phase-space and explored phase-space under constraint imposed by the reaction are clarified. The compatibility of experimental observations with a random clusterization is illustrated in a schematic scenario of a proton-nucleus collision. The role of randomness under constraint is also illustrated in the nucleus-nucleus case. (authors)

Reaction rate of propene pyrolysis.

Science.gov (United States)

Han, Peipei; Su, Kehe; Liu, Yan; Wang, Yanli; Wang, Xin; Zeng, Qingfeng; Cheng, Laifei; Zhang, Litong

2011-10-01

The reaction rate of propene pyrolysis was investigated based on the elementary reactions proposed in Qu et al., J Comput Chem 2009, 31, 1421. The overall reaction rate was developed with the steady-state approximation and the rate constants of the elementary reactions were determined with the variational transition state theory. For the elementary reaction having transition state, the vibrational frequencies of the selected points along the minimum energy path were calculated with density functional theory at B3PW91/6-311G(d,p) level and the energies were improved with the accurate model chemistry method G3(MP2). For the elementary reaction without transition state, the frequencies were calculated with CASSCF/6-311G(d,p) and the energies were refined with the multireference configuration interaction method MRCISD/6-311G(d,p). The rate constants were evaluated within 200-2000 K and the fitted three-parameter expressions were obtained. The results are consistent with those in the literatures in most cases. For the overall rate, it was found that the logarithm of the rate and the reciprocal temperature have excellent linear relationship above 400 K, predicting that the rate follows a typical first-order law at high temperatures of 800-2000 K, which is also consistent with the experiments. The apparent activation energy in 800-2000 K is 317.3 kJ/mol from the potential energy surface of zero Kelvin. This value is comparable with the energy barriers, 365.4 and 403.7 kJ/mol, of the rate control steps. However, the apparent activation energy, 215.7 kJ/mol, developed with the Gibbs free energy surface at 1200 K is consistent with the most recent experimental result 201.9 ± 0.6 kJ/mol. Copyright © 2011 Wiley Periodicals, Inc.

The astrophysical S-factor for the dd-reaction at ultralow energies

International Nuclear Information System (INIS)

Bystritskij, V.M.; Grebenyuk, V.M.; Parzhitskij, S.S.

1999-01-01

The experimental results for measurements of the astrophysical S-factor for dd-reaction at very low deuteron collision energies using liner plasma technique are presented. The experiment was fulfilled at the high current generator of the High-Current Electronics Institute, Tomsk, Russia. The measured values of S-factor for the deuteron collision energies: 2.27, 2.06, and 1.8 keV are: S dd = (53 ± 16), (64 ± 30), (114 ±68)b · keV, respectively. The corresponding dd cross sections described as a product of the barrier factor and measured astrophysical S-factor are: σ dd n (E col = 1.8 keV) = (4.3 ± 2.6) · 10 -33 cm 2 ; σ dd n (E col = 2.06 keV) = (9.8 ± 4.6) · 10 -33 cm 2 ; σ dd n (E col = 2.27 keV) = (2.1 ±0.6) · 10 -32 cm 2

Resonant elastic scattering, inelastic scattering and astrophysical reactions; Diffusion elastique resonante, diffusion inelastique et reactions astrophysiques

Energy Technology Data Exchange (ETDEWEB)

De Oliveira Santos, F. [Grand Accelerateur National d' Ions Lourds, UMR 6415, 14 - Caen (France)

2007-07-01

Nuclear reactions can occur at low kinetic energy. Low-energy reactions are characterized by a strong dependence on the structure of the compound nucleus. It turns out that it is possible to study the nuclear structure by measuring these reactions. In this course, three types of reactions are treated: Resonant Elastic Scattering (such as N{sup 14}(p,p)N{sup 14}), Inelastic Scattering (such as N{sup 14}(p,p')N{sup 14*}) and Astrophysical reactions (such as N{sup 14}(p,{gamma})O{sup 15}). (author)

Angular distribution and cross section measurements of 64Zn(n,α)61Ni reaction for neutron energy 5 MeV

International Nuclear Information System (INIS)

Chen Yingtang; Chen Zemin; Qi Huiquan; Li Mingtao

1995-01-01

A twin gridded ionization chamber with dual parameter data acquisition system is used to study neutron induced charged particle emission reaction. The angular distribution and cross section of α-particles from the 64 Zn(n,α) 61 Ni reaction are measured at neutron energy 5 MeV

The differential cross section of the 12C(p,p)12C reaction near the resonance at energy 1.726 MeV

International Nuclear Information System (INIS)

Duvanov, S.M.; Kobzev, A.P.

1996-01-01

New experimental results on the differential cross section of the 12 C(p,p) 12 C reaction near the separate resonance at 1726 keV were obtained for the 170 deg scattering angle. The cross section measured with a thin target has been used for computer simulation of the spectra measured for a defined initial proton energy for two thick targets. The precision measurements of the proton energies have been carried out using the resonance of 27 Al(p,γ) 28 Si reaction at 1726.0 keV. The energy scale of the excitation function of the 12 C(p,p) 12 C reaction near the resonance at 1726 keV has been defined more exactly. It will improve the precision of depth profiling of carbon in solids. 11 refs., 5 figs., 1 tab

Experimental determination of proton induced reaction cross sections on {sup nat}Ni near threshold energy

Energy Technology Data Exchange (ETDEWEB)

Uddin, Md. Shuza [Atomic Energy Research Establishment, Dhaka (Bangladesh). Tandem Accelerator Facilities; Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin, INM-5: Nuklearchemie; Chakraborty, Animesh Kumer [Atomic Energy Research Establishment, Dhaka (Bangladesh). Tandem Accelerator Facilities; Chittagong University of Engineering and Technology (Bangladesh). Dept. of Physics; Spellerberg, Stefan; Spahn, Ingo; Qaim, Syed M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin, INM-5: Nuklearchemie; Shariff, Md. Asad; Das, Sopan [Atomic Energy Research Establishment, Dhaka (Bangladesh). Tandem Accelerator Facilities; Rashid, Md. Abdur [Chittagong University of Engineering and Technology (Bangladesh). Dept. of Physics

2016-08-01

A newly developed facility at the 3 MV Tandem Accelerator at Dhaka for measurement of proton induced reaction cross sections in the energy region below 5 MeV is outlined and tests for the beam characterization are described. The results were validated by comparison with the well-known excitation function of the {sup 64}Ni(p, n){sup 64}Cu reaction. Excitation functions of the reactions {sup nat}Ni(p, x){sup 60,61}Cu, {sup nat}Ni(p, x){sup 55,57,58m+g}Co and {sup nat}Ni(p, x){sup 57}Ni were also measured from threshold to 16 MeV using the stacked-foil technique, whereby irradiations were performed with 5 MeV protons available at the Tandem Accelerator and 16.7 MeV protons at the BC 1710 cyclotron at Juelich, Germany. The radioactivity was measured using HPGe γ-ray detectors. A few results are new, the others strengthen the database. In particular, the results of the reaction {sup nat}Ni(p, x){sup 61}Cu below 3 MeV could serve as beam monitor.

Thermonuclear reaction listing

International Nuclear Information System (INIS)

Fukai, Yuzo

1993-01-01

The following 10 elements, including T, are well known as nuclear fusion fuels: p, D, T, 3 He, 4 He, 6 Li, 7 Li, 9 Be, 10 B, 11 B, ( 12 C, 13 C), where 12 C and 13 C are considered only in the calculation of Q value. Accordingly the number of the thermonuclear reactions is 55, and 78, if including carbon elements. The reactions have some branches. For the branches having two and three reaction products, the reaction products, Q value and threshold energy are calculated by using a computer. We have investigated those of the branches having more than three products from the papers of Ajzenberg-Selove and so on. And also, by the same papers, we check whether the above mentioned branch has been observed or not. The results are as follows: (I) the number of reactions which have Q 0 branches only with γ ray production, and Q 0 and neutron production is 36(17), and (IV) that of reactions whose branch with Q > 0 does not produce neutrons is 9(3). The value in the parentheses shows the number of the case of the carbon elements. For 55 thermonuclear reactions induced by lighter nuclides than 11 B, the reaction products, the values of Q and threshold energy, and the papers with reaction cross section data are presented in the tables. (author)

Mode specificity in the OH + CHD{sub 3} reaction: Reduced-dimensional quantum and quasi-classical studies on an ab initio based full-dimensional potential energy surface

Energy Technology Data Exchange (ETDEWEB)

Song, Hongwei, E-mail: hwsong@wipm.ac.cn; Yang, Minghui [Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Lu, Yunpeng [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Li, Jun [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Guo, Hua [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2016-04-28

An initial state selected time-dependent wave packet method is applied to study the dynamics of the OH + CHD{sub 3} reaction with a six-dimensional model on a newly developed full-dimensional ab initio potential energy surface (PES). This quantum dynamical (QD) study is complemented by full-dimensional quasi-classical trajectory (QCT) calculations on the same PES. The QD results indicate that both translational energy and the excitation of the CH stretching mode significantly promote the reaction while the excitation of the umbrella mode has a negligible effect on the reactivity. For this early barrier reaction, interestingly, the CH stretching mode is more effective than translational energy in promoting the reaction except at very low collision energies. These QD observations are supported by QCT results. The higher efficacy of the CH stretching model in promoting this early barrier reaction is inconsistent with the prediction of the naively extended Polanyi’s rules, but can be rationalized by the recently proposed sudden vector projection model.

Extension of a Kinetic Approach to Chemical Reactions to Electronic Energy Levels and Reactions Involving Charged Species with Application to DSMC Simulations

Science.gov (United States)

Liechty, Derek S.

2014-01-01

The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties are extended in the current work to include electronic energy level transitions and reactions involving charged particles. These extensions are shown to agree favorably with reported transition and reaction rates from the literature for near-equilibrium conditions. Also, the extensions are applied to the second flight of the Project FIRE flight experiment at 1634 seconds with a Knudsen number of 0.001 at an altitude of 76.4 km. In order to accomplish this, NASA's direct simulation Monte Carlo code DAC was rewritten to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced chemistry model, and to include the extensions presented in this work. The 1634 second data point was chosen for comparisons to be made in order to include a CFD solution. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid because, although near-transitional, the flow is still considered to be continuum. It is shown that the inclusion of electronic energy levels in the DSMC simulation is necessary for flows of this nature and is required for comparison to the CFD solution. The flow field solutions are also post-processed by the nonequilibrium radiation code HARA to compute the radiative portion.

Total reaction cross section of silicon induced by 4He in the energy range 3-10 MeV/u

International Nuclear Information System (INIS)

Ugryumov, V.Yu.; Kuznetsov, I.V.; Kalpakchieva, R.

2003-01-01

The energy dependence of total reaction cross section for α-particles on nat Si has been directly and accurately measured by the transmission method. These data show that σ R has different energy dependence from theoretical predictions at low energies. The σ R corrections due to inelastic scattering to the first excited state were made by integrating corresponding angular distributions

Total Reaction Cross Section of Silicon Induced by ^{4}He in the Energy Range 3-10 MeV/u

CERN Document Server

Ugryumov, V Yu; Basybekov, K B; Bialkowski, E; Budzanowski, A; Duysebaev, A D; Duysebaev, B A; Zholdybaev, T K; Ismailov, K M; Kadyrzhanov, K K; Kalpakchieva, R; Kugler, A; Kukhtina, I N; Kushniruk, V F; Kuterbekov, K A; Mukhambetzhan, A; Penionzhkevich, Yu E; Sadykov, B M; Skwirczynska, I; Sobolev, Yu G

2003-01-01

The energy dependence of total reaction cross section for alpha-particles on ^{nat}Si has been directly and accurately measured by the transmission method. These data show that sigma_R has different energy dependence from theoretical predictions at low energies. The sigma_R corrections due to inelastic scattering to the first excited state were made by integrating corresponding angular distributions.

Spallation reactions: calculations

International Nuclear Information System (INIS)

Bertini, H.W.

1975-01-01

Current methods for calculating spallation reactions over various energy ranges are described and evaluated. Recent semiempirical fits to existing data will probably yield the most accurate predictions for these reactions in general. However, if the products in question have binding energies appreciably different from their isotropic neighbors and if the cross section is approximately 30 mb or larger, then the intranuclear-cascade-evaporation approach is probably better suited. (6 tables, 12 figures, 34 references) (U.S.)

Multiparticle production in heavy-ion reactions

International Nuclear Information System (INIS)

Pelte, D.

1980-01-01

This lecture is concerned with the question how many particles and what kind of them are produced in heavy-ion collisions at energies about 10 MeV/n. We tend to assume that heavy-ion reactions at this energy are binary reactions. The experimental set consisting of two large ionization chambers serving to detection, in coincidence, the reaction fragments is described. With this set-up a number of reactions induced on 27 Al, 28 Si and 40 Ca by the 32 S beam of 135 and 190 MeV energy has been studied. Two-fragments inclusive and exclusive reactions were investigated. The assumption of a sequential statistical decay gives the best agreement with the data for all analyzed cases. (H.M.)

Competitive cation binding computations of proton balance for reactions of the phosphagen and glycolytic energy systems within skeletal muscle

Science.gov (United States)

2017-01-01

Limited research and data has been published for the H+ coefficients for the metabolites and reactions involved in non-mitochondrial energy metabolism. The purpose of this investigation was to compute the fractional binding of H+, K+, Na+ and Mg2+ to 21 metabolites of skeletal muscle non-mitochondrial energy metabolism, resulting in 104 different metabolite-cation complexes. Fractional binding of H+ to these metabolite-cation complexes were applied to 17 reactions of skeletal muscle non-mitochondrial energy metabolism, and 8 conditions of the glycolytic pathway based on the source of substrate (glycogen vs. glucose), completeness of glycolytic flux, and the end-point of pyruvate vs. lactate. For pH conditions of 6.0 and 7.0, respectively, H+ coefficients (-‘ve values = H+ release) for the creatine kinase, adenylate kinase, AMP deaminase and ATPase reactions were 0.8 and 0.97, -0.13 and -0.02, 1.2 and 1.09, and -0.01 and -0.66, respectively. The glycolytic pathway is net H+ releasing, regardless of lactate production, which consumes 1 H+. For glycolysis fueled by glycogen and ending in either pyruvate or lactate, H+ coefficients for pH 6.0 and 7.0 were -3.97 and -2.01 (pyruvate), and -1.96 and -0.01 (lactate), respectively. When starting with glucose, the same conditions result in H+ coefficients of -3.98 and -2.67, and -1.97 and –0.67, respectively. The most H+ releasing reaction of glycolysis is the glyceraldehyde-3-phosphate dehydrogenase reaction, with H+ coefficients for pH 6.0 and 7.0 of -1.58 and -0.76, respectively. Incomplete flux of substrate through glycolysis would increase net H+ release due to the absence of the pyruvate kinase and lactate dehydrogenase reactions, which collectively result in H+ coefficients for pH 6.0 and 7.0 of 1.35 and 1.88, respectively. The data presented provide an extensive reference source for academics and researchers to accurately profile the balance of protons for all metabolites and reactions of non-mitochondrial energy

Competitive cation binding computations of proton balance for reactions of the phosphagen and glycolytic energy systems within skeletal muscle.

Science.gov (United States)

Robergs, Robert Andrew

2017-01-01

Limited research and data has been published for the H+ coefficients for the metabolites and reactions involved in non-mitochondrial energy metabolism. The purpose of this investigation was to compute the fractional binding of H+, K+, Na+ and Mg2+ to 21 metabolites of skeletal muscle non-mitochondrial energy metabolism, resulting in 104 different metabolite-cation complexes. Fractional binding of H+ to these metabolite-cation complexes were applied to 17 reactions of skeletal muscle non-mitochondrial energy metabolism, and 8 conditions of the glycolytic pathway based on the source of substrate (glycogen vs. glucose), completeness of glycolytic flux, and the end-point of pyruvate vs. lactate. For pH conditions of 6.0 and 7.0, respectively, H+ coefficients (-'ve values = H+ release) for the creatine kinase, adenylate kinase, AMP deaminase and ATPase reactions were 0.8 and 0.97, -0.13 and -0.02, 1.2 and 1.09, and -0.01 and -0.66, respectively. The glycolytic pathway is net H+ releasing, regardless of lactate production, which consumes 1 H+. For glycolysis fueled by glycogen and ending in either pyruvate or lactate, H+ coefficients for pH 6.0 and 7.0 were -3.97 and -2.01 (pyruvate), and -1.96 and -0.01 (lactate), respectively. When starting with glucose, the same conditions result in H+ coefficients of -3.98 and -2.67, and -1.97 and -0.67, respectively. The most H+ releasing reaction of glycolysis is the glyceraldehyde-3-phosphate dehydrogenase reaction, with H+ coefficients for pH 6.0 and 7.0 of -1.58 and -0.76, respectively. Incomplete flux of substrate through glycolysis would increase net H+ release due to the absence of the pyruvate kinase and lactate dehydrogenase reactions, which collectively result in H+ coefficients for pH 6.0 and 7.0 of 1.35 and 1.88, respectively. The data presented provide an extensive reference source for academics and researchers to accurately profile the balance of protons for all metabolites and reactions of non-mitochondrial energy

Competitive cation binding computations of proton balance for reactions of the phosphagen and glycolytic energy systems within skeletal muscle.

Directory of Open Access Journals (Sweden)

Robert Andrew Robergs

Full Text Available Limited research and data has been published for the H+ coefficients for the metabolites and reactions involved in non-mitochondrial energy metabolism. The purpose of this investigation was to compute the fractional binding of H+, K+, Na+ and Mg2+ to 21 metabolites of skeletal muscle non-mitochondrial energy metabolism, resulting in 104 different metabolite-cation complexes. Fractional binding of H+ to these metabolite-cation complexes were applied to 17 reactions of skeletal muscle non-mitochondrial energy metabolism, and 8 conditions of the glycolytic pathway based on the source of substrate (glycogen vs. glucose, completeness of glycolytic flux, and the end-point of pyruvate vs. lactate. For pH conditions of 6.0 and 7.0, respectively, H+ coefficients (-'ve values = H+ release for the creatine kinase, adenylate kinase, AMP deaminase and ATPase reactions were 0.8 and 0.97, -0.13 and -0.02, 1.2 and 1.09, and -0.01 and -0.66, respectively. The glycolytic pathway is net H+ releasing, regardless of lactate production, which consumes 1 H+. For glycolysis fueled by glycogen and ending in either pyruvate or lactate, H+ coefficients for pH 6.0 and 7.0 were -3.97 and -2.01 (pyruvate, and -1.96 and -0.01 (lactate, respectively. When starting with glucose, the same conditions result in H+ coefficients of -3.98 and -2.67, and -1.97 and -0.67, respectively. The most H+ releasing reaction of glycolysis is the glyceraldehyde-3-phosphate dehydrogenase reaction, with H+ coefficients for pH 6.0 and 7.0 of -1.58 and -0.76, respectively. Incomplete flux of substrate through glycolysis would increase net H+ release due to the absence of the pyruvate kinase and lactate dehydrogenase reactions, which collectively result in H+ coefficients for pH 6.0 and 7.0 of 1.35 and 1.88, respectively. The data presented provide an extensive reference source for academics and researchers to accurately profile the balance of protons for all metabolites and reactions of non

Solving The Longstanding Problem Of Low-Energy Nuclear Reactions At the Highest Microscopic Level - Final Report

Energy Technology Data Exchange (ETDEWEB)

Quaglioni, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-09-22

A 2011 DOE-NP Early Career Award (ECA) under Field Work Proposal (FWP) SCW1158 supported the project “Solving the Long-Standing Problem of Low-Energy Nuclear Reactions at the Highest Microscopic Level” in the five-year period from June 15, 2011 to June 14, 2016. This project, led by PI S. Quaglioni, aimed at developing a comprehensive and computationally efficient framework to arrive at a unified description of structural properties and reactions of light nuclei in terms of constituent protons and neutrons interacting through nucleon-nucleon (NN) and three-nucleon (3N) forces. Specifically, the project had three main goals: 1) arriving at the accurate predictions for fusion reactions that power stars and Earth-based fusion facilities; 2) realizing a comprehensive description of clustering and continuum effects in exotic nuclei, including light Borromean systems; and 3) achieving fundamental understanding of the role of the 3N force in nuclear reactions and nuclei at the drip line.

Measurement of D(d,p)T Reaction Cross Sections in Sm Metal in Low Energy Region (10(≤) Ed(≤)20 keV)

Institute of Scientific and Technical Information of China (English)

WANG Tie-Shan; YANG Zhen; H. Yunemura; A. Nakagawa; LV Hui-Yi; CHEN Jian-Yong; LIU Sheng-Jin; J. Kasagi

2007-01-01

To study the screening effect of nuclear reactions in metallic environments, the thick target yields, the cross sections and the experimental S(E) factors of the D{d,p)T reaction have been measured on deuterons implanted in Sm metal at 133.2 K for beam energies ranging from 10 to 20keV. The thick target yields of protons emitted in the D(d,p)T reaction are measured and compared with those data extrapolated from cross sections and stopping power data at higher energies. The screening potential in Sm metal at 133.2K is deduced to be 520±56eV. As compared with the value achieved in the gas target, the calculated screening potential values are much larger. This screening potential cannot be simply interpreted only by the electron screening. Energy dependences of the cross section cr(E) and the experimental S(E) factor for D(d,p)T reaction in Sm metal at 133.2K are obtained, respectively.

Low energy electron-initiated ion-molecule reactions of ribose analogues

International Nuclear Information System (INIS)

Mozejko, P.

2003-01-01

Recent experiments in which plasmid DNA samples were bombarded with low energy ( 2 O, DNA bases, and sugar-phosphate backbone analogues. To this end, the cyclic molecule tetrahydrofuran, and its derivatives, provide useful models for the sugar-like molecules contained in the backbone of DNA. In addition to LEE induced dissociation by processes such as dissociative electron attachment (DEA), molecules may be damaged by ions and neutral species of non-thermal energies created by LEE in the surrounding environment. In this contribution, we investigate with electron stimulated desorption techniques, LEE damage to films of desoxy-ribose analogues in the presence of various molecular coadsorbates, that simulate changes in local molecular environment. In one type of experiments tetrahydrofuran is deposited onto multilayer O2. A desorbed signal of OH - indicates ion-molecule reactions of the type O - + C 4 H 8 O -> OH - + C 4 H 7 O, where the O - was formed initially by DEA to O 2 . Further electron stimulated desorption measurements for tetrahydrofuran and derivatives adsorbed on H 2 O, Kr, N 2 O and CH 3 OH will be presented and discussed

Reaction-rate coefficients, high-energy ions slowing-down, and power balance in a tokamak fusion reactor plasma

International Nuclear Information System (INIS)

Tone, Tatsuzo

1978-07-01

Described are the reactivity coefficient of D-T fusion reaction, slowing-down processes of deuterons injected with high energy and 3.52 MeV alpha particles generated in D-T reaction, and the power balance in a Tokamak reactor plasma. Most of the results were obtained in the first preliminary design of JAERI Experimental Fusion Reactor (JXFR) driven with stationary neutral beam injection. A manual of numerical computation program ''BALTOK'' developed for the calculations is given in the appendix. (auth.)

The D(+) + H2 reaction: differential and integral cross sections at low energy and rate constants at low temperature.

Science.gov (United States)

González-Lezana, Tomás; Scribano, Yohann; Honvault, Pascal

2014-08-21

The D(+) + H2 reaction is investigated by means of a time independent quantum mechanical (TIQM) and statistical quantum mechanical (SQM) methods. Differential cross sections and product rotational distributions obtained with these two theoretical approaches for collision energies between 1 meV and 0.1 eV are compared to analyze the dynamics of the process. The agreement observed between the TIQM differential cross sections and the SQM predictions as the energy increases revealed the role played by the complex-forming mechanism. The importance of a good description of the asymptotic regions is also investigated by calculating rate constants for the title reaction at low temperature.

On the ultrafast kinetics of the energy and electron transfer reactions in photosystem I

Energy Technology Data Exchange (ETDEWEB)

Slavov, Chavdar Lyubomirov

2009-07-09

The subject of the current work is one of the main participants in the light-dependent phase of oxygenic photosynthesis, Photosystem I (PS I). This complex carries an immense number of cofactors: chlorophylls (Chl), carotenoids, quinones, etc, which together with the protein entity exhibit several exceptional properties. First, PS I has an ultrafast light energy trapping kinetics with a nearly 100% quantum efficiency. Secondly, both of the electron transfer branches in the reaction center are suggested to be active. Thirdly, there are some so called 'red' Chls in the antenna system of PS I, absorbing light with longer wavelengths than the reaction center. These 'red' Chls significantly modify the trapping kinetics of PS I. The purpose of this thesis is to obtain better understanding of the above-mentioned, specific features of PS I. This will not merely cast more light on the mechanisms of energy and electron transfer in the complex, but also will contribute to the future developments of optimized artificial light-harvesting systems. In the current work, a number of PS I complexes isolated from different organisms (Thermosynechococcus elongatus, Chlamydomonas reinhardtii, Arabidopsis thaliana) and possessing distinctive features (different macroorganisation, monomers, trimers, monomers with a semibelt of peripheral antenna attached; presence of 'red' Chls) is investigated. The studies are primarily focused on the electron transfer kinetics in each of the cofactor branches in the PS I reaction center, as well as on the effect of the antenna size and the presence of 'red' Chls on the trapping kinetics of PS I. These aspects are explored with the help of several ultrafast optical spectroscopy methods: (i) time-resolved fluorescence ? single photon counting and synchroscan streak camera; and (ii) ultrafast transient absorption. Physically meaningful information about the molecular mechanisms of the energy trapping in PS I is

Nuclear fission and reactions

International Nuclear Information System (INIS)

Anon.

1975-01-01

The nuclear fission research programs are designed to elucidate basic features of the fission process. Specifically, (1) factors determining how nucleons of a fissioning nucleus are distributed between two fission fragments, (2) factors determining kinetic energy and excitation energies of fragments, and (3) factors controlling fission lifetimes. To these ends, fission studies are reported for several heavy elements and include investigations of spontaneous and neutron-induced fission, heavy ion reactions, and high energy proton reactions. The status of theoretical research is also discussed. (U.S.)

Temperature and excitation energy of hot nuclei in the reaction of 40Ar+197Au at 25 MeV/nucleon

International Nuclear Information System (INIS)

Wu, H.; Jin, G.; Li, Z.; Dai, G.; Qi, Y.; He, Z.; Luo, Q.; Duan, L.; Wen, W.; Zhang, B.

1997-01-01

The coincidence measurements between heavy fission fragments and light charged particles with Z ≤2 were carried out for the 40 Ar+ 197 Au reaction at 25 MeV/nucleon, to study the properties of hot nuclei in heavy ion induced reactions. The linear momentum transfers (LMTs) were deduced from the folding angle and the time-of-flight difference between two fission fragments of heavy residues. The relationship of the nuclear temperature (slope parameter of the energy spectrum) and the excitation energy was determined independently from the measurement of the kinetic energy spectra in the frames of the emitting sources and from the LMT analysis. Both the temperature and the excitation energy increase with decreasing impact parameter, which suggests that a plateau temperature of 5.5 MeV is reached at an excitation energy of 3.1 MeV/nucleon. The result was also compared with various statistical models that explain the plateau by the multifragmentation process, where the excitation energy is assumed to be stored in compression and expansion effects. (orig.)

Origin of a maximum of the astrophysical S factor in heavy-ion fusion reactions at deep subbarrier energies

Science.gov (United States)

Hagino, K.; Balantekin, A. B.; Lwin, N. W.; Thein, Ei Shwe Zin

2018-03-01

The hindrance phenomenon of heavy-ion fusion cross sections at deep subbarrier energies often accompanies a maximum of an astrophysical S factor at a threshold energy for fusion hindrance. We argue that this phenomenon can naturally be explained when the fusion excitation function is fitted with two potentials, with a larger (smaller) logarithmic slope at energies lower (higher) than the threshold energy. This analysis clearly suggests that the astrophysical S factor provides a convenient tool to analyze the deep subbarrier hindrance phenomenon, even though the S factor may have a strong energy dependence for heavy-ion systems unlike that for astrophysical reactions.

Dissipative processes in 18O + 9Be and 18O + 181Ta reactions at Fermi energies

International Nuclear Information System (INIS)

Erdemchimeg, B.; Mikhailova, T.I.; Artyukh, A.G.; Kaminski, G.; Sereda, Yu.M.; Erdemchimeg, B.; Kaminski, G.; Sereda, Yu.M.; Colonna, M.; Di Toro, M.; Wolter, H.H.

2010-01-01

A study of peripheral nuclear collisions at Fermi energies with transport models is presented. It is motivated by experiments devoted to studying of isotopic yields in the reactions 18 O on 9 Be and 181 Ta at E/A = 35 MeV measured at very forward angles. The data show a two-component structure, one centered at beam velocity ('direct component') and another at lower velocities ('dissipative component'). It is shown that the transport calculations describe the general features of the dissipative component of the reaction. In our calculations we take into account the evaporation of the excited, primary projectile-like residues due to statistical decay. This improves the comparison of the results of the calculations with experiment. We find substantially different behavior of the dissipative component in the reactions with light and heavy target.

Dilepton spectroscopy at intermediate energies; the carbon - carbon reaction at 1 GeV/A; Spectroscopie des dileptons aux energies intermediaires; la reaction carbone - carbone A 1 GeV/A

Energy Technology Data Exchange (ETDEWEB)

Prunet, M

1995-06-01

The Physics context of this work is heavy ion collisions at relativistic energies where di-electron provide informations on the produced hot and dense nuclear matter. The experiment is performed by the DiLepton Spectrometer (DLS) Collaboration at the Lawrence Berkeley`s Bevalac. After a description of the apparatus, we review the whole program and the main results so far obtained: first evidence of a significant di-electron signal at energies above 1 GeV/A; improvement of the understanding of di-electron production (electromagnetic decays of hadrons, {pi}{sup +}{pi}{sup -} annihilation and hadronic Bremsstrahlung). The results of p-p, p-d reactions from 1 to 4.9 GeV/A show that hadronic Bremsstrahlung (pp, pn) should be reformulated. Our analysis, optimized on the reaction Carbon-Carbon at 1 GeV/A, has been applied to {alpha}-Ca and d-Ca. We have developed two main aspects: improvement of the time resolution (500 ps) in order to eliminate all of the protons. Improvement of the space resolution (300 {mu}) for better mass resolution, in particular in the {rho} region. We obtain the cross section of di-electron production as a function of mass, transverse momentum and rapidity from the C-C, {alpha}-Ca and d-Ca reactions at 1 GeV/A. We also compare the cross section for all of the measured systems at 1 GeV/A, including Ca-Ca, and we show a (ApAt){sup {alpha}} dependence with {alpha} {approx_equal} 1.1. A study of the associated multiplicity has also been performed. Nevertheless, the limited acceptance of the DLS and its poor mass resolution to identify the {rho}, {omega} vector mesons, do not allow to conclude on hadron behaviour in nuclear matter. This point is one of the main goal of the HADES project at GSI (Darmstadt), which we give a brief description of the main features. (authors). 60 refs.

Investigation of the reaction {sup 4}He(γ, pn)d at energies below the meson-production threshold

Energy Technology Data Exchange (ETDEWEB)

Khodyachikh, A. F.; Gorbenko, E. S.; Murtazin, R. T., E-mail: rumurtazin@gmail.com [Kharkiv Institute of Physics and Technology: National Science Center (Ukraine)

2017-01-15

The momentum distributions of deuterons and nucleons from the reaction {sup 4}He(γ, pn)d induced by bremsstrahlung photons whose spectrum extends up to the endpoint energy of 150 MeV were measured by means of a diffusion chamber placed in a magnetic field. These measurements were performed in four photon-energy intervals for deuterons and in the energy range between 100 and 150 MeV for nucleons. Angular and energy correlations of nucleons were measured at photon energies in the interval between 50 and 70 MeV. The results obtained in this way were analyzed on the basis of the quasideuteron model. The probability for final-state nucleon–deuteron interaction was estimated.

A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products

Energy Technology Data Exchange (ETDEWEB)

Kuznetsov, A.V.; Veldhuizen, E.J. van; Westerberg, L.; Lyapin, V.G.; Aleklett, K.; Loveland, W.; Bondorf, J.; Jakobsson, B.; Whitlow, H.J.; El Bouanani, M

2000-10-01

A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products from nuclear reactions has been designed and tested at the CELSIUS storage ring in Uppsala. The construction is based on MicroChannel Plate (MCP) time detectors of the electron mirror type and silicon p-i-n diodes, and permits the detectors to be stacked side-by-side to achieve large solid angle coverage. This kind of telescope measures the Time of Flight (ToF) and Energy (E) of the particle from which one can reconstruct mass. The combination of an ultra-thin cluster gas-jet target and thin carbon emitter foils allows one to measure heavy residues down to an energy of {approx}35 keV/nucleon from the interactions of 400 MeV/nucleon {sup 16}O with {sup nat}Xe gas targets.

A compact Ultra High Vacuum (UHV) compatible instrument for time of flight energy measurements of slow heavy reaction products

International Nuclear Information System (INIS)

Kuznetsov, A.V.; Loveland, W.; Jakobsson, B.; Whitlow, H.J.; Bouanani, M. El; Univ. of North Texas, Denton, TX

2000-01-01

A compact Ultra High Vacuum (UHV) compatible instrument for time of flight energy measurements of slow heavy reaction products from nuclear reactions has been designed and tested at the CELSIUS storage ring in Uppsala. The construction is based on MicroChannel Plate time detectors of the electron mirror type and silicon p-i-n diodes, and permits the detectors to be stacked side-by-side to achieve large solid angle coverage. This kind of telescope measures the Time of Flight (ToF) and Energy (E) of the particle from which one can reconstruct mass. The combination of an ultra-thin cluster gas-jet target and thin carbon emitter foils allows one to measure heavy residues down to an energy of ∼ 35 keV/nucleon from the interactions of 400 MeV/nucleon 16 O with nat Xe gas targets

A compact Ultra High Vacuum (UHV) compatible instrument for time of flight energy measurements of slow heavy reaction products

Energy Technology Data Exchange (ETDEWEB)

Kuznetsov, A.V. [V.G.Khlopin Radium Institute, St. Petersburg (Russian Federation); Uppsala Univ. (Sweden). The Svedberg Lab.; Veldhuizen, E.J. van; Aleklett, K. [Uppsala Univ., (Sweden). Dept. of Radiation Sciences; Westerberg, L. [Uppsala University (Sweden). The Svedberg Lab.; Lyapin, V.G. [V.G.Khlopin Radium Institute, St. Petersburg (Russian Federation); Loveland, W. [Oregon State Univ., Corvallis, OR (United States). Dept. of Chemistry; Bondorf, J. [Niels Bohr Inst., Copenhagen (Denmark); Jakobsson, B. [Lund Univ. (Sweden). Dept. of Physics; Whitlow, H.J. [Lund Univ. (Sweden). Dept. of Nuclear Physics; Bouanani, M. El [Lund Univ. (Sweden). Dept. of Nuclear Physics; Univ. of North Texas, Denton, TX (United States). Dept. of Physics

2000-07-01

A compact Ultra High Vacuum (UHV) compatible instrument for time of flight energy measurements of slow heavy reaction products from nuclear reactions has been designed and tested at the CELSIUS storage ring in Uppsala. The construction is based on MicroChannel Plate time detectors of the electron mirror type and silicon p-i-n diodes, and permits the detectors to be stacked side-by-side to achieve large solid angle coverage. This kind of telescope measures the Time of Flight (ToF) and Energy (E) of the particle from which one can reconstruct mass. The combination of an ultra-thin cluster gas-jet target and thin carbon emitter foils allows one to measure heavy residues down to an energy of {approx} 35 keV/nucleon from the interactions of 400 MeV/nucleon {sup 16}O with {sup nat} Xe gas targets.

A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products

International Nuclear Information System (INIS)

Kuznetsov, A.V.; Veldhuizen, E.J. van; Westerberg, L.; Lyapin, V.G.; Aleklett, K.; Loveland, W.; Bondorf, J.; Jakobsson, B.; Whitlow, H.J.; El Bouanani, M.

2000-01-01

A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products from nuclear reactions has been designed and tested at the CELSIUS storage ring in Uppsala. The construction is based on MicroChannel Plate (MCP) time detectors of the electron mirror type and silicon p-i-n diodes, and permits the detectors to be stacked side-by-side to achieve large solid angle coverage. This kind of telescope measures the Time of Flight (ToF) and Energy (E) of the particle from which one can reconstruct mass. The combination of an ultra-thin cluster gas-jet target and thin carbon emitter foils allows one to measure heavy residues down to an energy of ∼35 keV/nucleon from the interactions of 400 MeV/nucleon 16 O with nat Xe gas targets

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15-December 31, 1984

International Nuclear Information System (INIS)

1985-01-01

Energetic halogen atoms or ions, activated by various nuclear transformations are studied in gas, high pressure and condensed phase saturated and unsaturated hydrocarbons, halomethanes, and liquid and solid aqueous solutions of biomolecular and organic solutes in order to understand better the mechanisms and dynamics of high energy monovalent species. The experimental program and its goals remain the same, consisting of four interrelated areas: (1) The stereochemistry of energetic 18 F, /sup 34m/Cl, and 38 Cl substitution reactions with chiral molecules in the gas and condensed phase is studied. (2) The gas to condensed state transition in halogen high energy chemistry, involving energetic chlorine, bromine, and iodine reactions in halomethanes, saturated and unsaturated hydrocarbons and aqueous solutions of biomolecules and alkyl halides is being investigated in more detail. Current attention is given to defining the nature of the enhancement yields in the condensed phase. Specifically, energetic halogen reactions in liquid and frozen aqueous solutions or organic and biomolecular solutes are studied. (3) Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular and organic solutes in liquid and frozen aqueous solutions are being studied in an attempt to learn more about the activation events in the condensed phase. (4) The applications of hot chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Current attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as site indicators in liquid and frozen aqueous solutions of halogenated bases and nucleosides are currently being developed. 14 references

Angular dependences of the tensor analyzing powers in the dd→3Hen reaction at intermediate energies

International Nuclear Information System (INIS)

Ladygin, V.P.; Ladygina, N.B.

2002-01-01

The tensor analyzing powers A yy , A xx , and A xz in the dd→ 3 Hen reaction at intermediate energies are considered in the framework of the one-nucleon-exchange approximation. Their strong sensitivity to the 3 He and deuteron spin structure at short distances is shown

Multipolarity analysis for 14C high-energy resonance populated by (18O,16O) two-neutron transfer reaction

International Nuclear Information System (INIS)

Carbone, D.; Cavallaro, M.; Bondì, M.; Agodi, C.; Cunsolo, A.; Cappuzzello, F.; Azaiez, F.; Franchoo, S.; Khan, E.; Bonaccorso, A.; Fortunato, L.; Foti, A.; Linares, R.; Lubian, J.; Scarpaci, J. A.; Vitturi, A.

2015-01-01

The 12 C( 18 O, 16 O) 14 C reaction at 84 MeV incident energy has been explored up to high excitation energy of the residual nucleus thanks to the use of the MAGNEX spectrometer to detect the ejectiles. In the region above the two-neutron separation energy, a resonance has been observed at 16.9 MeV. A multipolarity analysis of the cross section angular distribution indicates an L = 0 character for such a transition

The 1H(t,n)3He reaction as monoenergetic neutron source in the (10/20) MeV energy interval

International Nuclear Information System (INIS)

Zago, G.

1981-01-01

The 1 H(t,n) 3 He reaction, considered as a neutron source in the (10/20) MeV energy interval, is a ''white'' neutron source having intensity, mean energy, and directionality which may prove advantageous in technological and biomedical researches. (author)

Towards an unambiguous determination of the excitation energy of the projectile in heavy-ion reactions?

Energy Technology Data Exchange (ETDEWEB)

Buta, A.M.; Steckmeyer, J.C. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Auger, G. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)] [and others

2002-03-01

The excitation energy of the quasi-projectiles produced in heavy-ion collisions is determined for the {sup 58}Ni+{sup 197}Au reactions at 52 and 90 AMeV. A new method is proposed for isolating unambiguously the particles evaporated by the source. It consists in observing them at small angles along the flight direction of the source. (authors)

Electronic dissipation processes during chemical reactions on surfaces

CERN Document Server

Stella, Kevin

2012-01-01

Hauptbeschreibung Every day in our life is larded with a huge number of chemical reactions on surfaces. Some reactions occur immediately, for others an activation energy has to be supplied. Thus it happens that though a reaction should thermodynamically run off, it is kinetically hindered. Meaning the partners react only to the thermodynamically more stable product state within a mentionable time if the activation energy of the reaction is supplied. With the help of catalysts the activation energy of a reaction can be lowered. Such catalytic processes on surfaces are widely used in industry. A

Extension of a Kinetic Approach to Chemical Reactions to Electronic Energy Levels and Reactions Involving Charged Species With Application to DSMC Simulations

Science.gov (United States)

Liechty, Derek S.

2013-01-01

The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties are extended in the current work to include electronic energy level transitions and reactions involving charged particles. These extensions are shown to agree favorably with reported transition and reaction rates from the literature for nearequilibrium conditions. Also, the extensions are applied to the second flight of the Project FIRE flight experiment at 1634 seconds with a Knudsen number of 0.001 at an altitude of 76.4 km. In order to accomplish this, NASA's direct simulation Monte Carlo code DAC was rewritten to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced chemistry model, and to include the extensions presented in this work. The 1634 second data point was chosen for comparisons to be made in order to include a CFD solution. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid because, although near-transitional, the flow is still considered to be continuum. It is shown that the inclusion of electronic energy levels in the DSMC simulation is necessary for flows of this nature and is required for comparison to the CFD solution. The flow field solutions are also post-processed by the nonequilibrium radiation code HARA to compute the radiative portion of the heating and is then compared to the total heating measured in flight.

Update of ENDF/B-V Mod 3 iron: neutron-producing reaction cross sections and energy-angle correlations

International Nuclear Information System (INIS)

Fu, C.Y.; Hetrick, D.M.

1986-07-01

An update of the ENDF/B-V Mod-3 evaluation for natural iron is described. The cross sections of (n,n') and (n,2n) reactions are revised. Energy-angle correlations in the secondary (n,n') neutrons are introduced in the ENDF/B-V formats. Anisotropic angular distributions are provided for the secondary neutrons in (n,2n), (n,np), and (n,nα) reactions. Revelant integral results, microscopic data, and nuclear model calculations that influence the revised results are summarized. 54 refs., 9 figs., 2 tabs

Effect of temperature on a free energy and equilibrium constants during dry flue gas desulphurisation chemical reactions

Directory of Open Access Journals (Sweden)

Kuburović Miloš

2002-01-01

Full Text Available During dry flue gas desulphurisation (FGD dry particles of reagents are inserted (injected in the stream of flue gas, where they bond SO2. As reagents, the most often are used compounds of calcium (CaCO3, CaO or Ca(OH2. Knowledge of free energy and equilibrium constants of chemical reactions during dry FGD is necessary for understanding of influence of flue gas temperature to course of these chemical reactions as well as to SO2 bonding from flue gases.

Energy transfer and reaction dynamics of matrix-isolated 1,2-difluoroethane-d4

Science.gov (United States)

Raff, Lionel M.

1990-09-01

The molecular dynamics of vibrationally excited 1,2-difluoroethane-d4 isolated in Ar, Kr, and Xe matrices at 12 K are investigated using trajectory methods. The matrix model is an fcc crystal containing 125 unit cells with 666 atoms in a cubic (5×5×5) arrangement. It is assumed that 1,2-difluoroethane-d4 is held interstitially within the volume bounded by the innermost unit cell of the crystal. The transport effects of the bulk are simulated using the velocity reset method introduced by Riley, Coltrin, and Diestler [J. Chem. Phys. 88, 5934 (1988)]. The system potential is written as the separable sum of a lattice potential, a lattice-molecule interaction and a gas-phase potential for 1,2-difluoroethane. The first two of these are assumed to have pairwise form while the molecular potential is a modified form of the global potential previously developed for 1,2-difluoroethane [J. Phys. Chem. 91, 3266 (1987)]. Calculated sublimation energies for the pure crystals are in good accord with the experimental data. The distribution of metastable-state energies for matrix-isolated 1,2-difluoroethane-d4 is Gaussian in form. In krypton, the full width at half maximum for the distribution is 0.37 eV. For a total excitation energy of 6.314 eV, the observed dynamic processes are vibrational relaxation, orientational exchange, and four-center DF elimination reactions. The first of these processes is characterized by a near linear, first-order decay curve with rate coefficients in the range 1.30-1.48×1011 s-1. The average rates in krypton and xenon are nearly equal. The process is slightly slower in argon. The decay curves exhibit characteristic high-frequency oscillations that are generally seen in energy transfer studies. It is demonstrated that these oscillations are associated with the frequencies for intramolecular energy transfer so that the entire frequency spectrum for such transfer processes can be obtained from the Fourier transform of the decay curve. Orientational

Reactivity of Single-Walled Carbon Nanotubes in the Diels-Alder Cycloaddition Reaction: Distortion-Interaction Analysis along the Reaction Pathway.

Science.gov (United States)

Li, Yingzi; Osuna, Sílvia; Garcia-Borràs, Marc; Qi, Xiaotian; Liu, Song; Houk, Kendall N; Lan, Yu

2016-08-26

Diels-Alder cycloaddition is one of the most powerful tools for the functionalization of single-walled carbon nanotubes (SWCNTs). Density functional theory at the B3-LYP level of theory has been used to investigate the reactivity of different-diameter SWCNTs (4-9,5) in Diels-Alder reactions with 1,3-butadiene; the reactivity was found to decrease with increasing SWCNT diameter. Distortion/interaction analysis along the whole reaction pathway was found to be a better way to explore the reactivity of this type of reaction. The difference in interaction energy along the reaction pathway is larger than that of the corresponding distortion energy. However, the distortion energy plots for these reactions show the same trend. Therefore, the formation of the transition state can be determined from the interaction energy. A lower interaction energy leads to an earlier transition state, which indicates a lower activation energy. The computational results also indicate that the original distortion of the SWCNTs leads to an increase in the reactivity of the SWCNTs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nuclear chemistry research of high-energy nuclear reactions at Carnegie-Mellon University, 1961--1977. Summary report. [Summaries of research activities at Carnegie-Mellon University

Energy Technology Data Exchange (ETDEWEB)

Caretto, A.A. Jr.

1977-11-01

The activities and the results of research in the study of high energy nuclear reactions carried out at Carnegie Institute of Technology from 1957 to 1967 and at Carnegie-Mellon University from 1967 to 1977 are summarized. A complete list of all publications, doctoral dissertations, and reports resulting from the research of this project is also included. A major part of the report is a review of the research activities and results. The objective of the research of this project was the study of reactions initiated by projectiles of energy above about 100 MeV. The main effort was the investigation of simple nuclear reactions with the objective to deduce reaction mechanisms. These reactions were also used as probes to determine the nuclear structure of the target. In addition, a number of studies of spallation reactions were undertaken which included the determination of excitation functions and recoil properties. Recent research activities which have involved the study of pion induced reactions as well as reactions initiated by heavy ions is also discussed.

Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

Directory of Open Access Journals (Sweden)

Mazzocco M.

2017-01-01

Full Text Available The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

Science.gov (United States)

Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Strano, E.; Torresi, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Marquinez-Duran, G.; Martel, I.; Nicoletto, M.; Pakou, A.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stroe, L.

2017-11-01

The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

Resonance strength measurement at astrophysical energies: The {sup 17}O(p,α){sup 14}N reaction studied via Trojan Horse Method

Energy Technology Data Exchange (ETDEWEB)

Sergi, M. L., E-mail: sergi@lns.infn.it; La Cognata, M.; Pizzone, R. G. [INFN, Laboratori Nazionali del Sud, Catania (Italy); Spitaleri, C. [INFN, Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli studi di Catania, Catania (Italy); Lamia, L.; Rapisarda, G. G. [Dipartimento di Fisica e Astronomia, Università degli studi di Catania, Catania (Italy); Mukhamedzhanov, A. [Cyclotron Institute, Texas A& M University, College Station, Texas 77843 (United States); Irgaziev, B. [GIK Institute of Engineering Sciences and Technology, Topi, Districti Swabi, Khyber Pakhtunkhwa (Pakistan); Tang, X. D.; Wiescher, M. [Department of Physics, Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame 46556, Indiana (United States); Mrazek, J.; Kroha, V. [Nuclear Physics Institute of ASCR, Rez (Czech Republic)

2015-10-15

In recent years, the Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of proton-induced reactions on {sup 17}O nuclei, overcoming extrapolation procedures and enhancement effects due to electron screening. We will report on the indirect study of the {sup 17}O(p,α){sup 14}N reaction via the THM by applying the approach developed for extracting the resonance strength of narrow resonance in the ultralow energy region. Two measurements will be described and the experimental THM cross sections will be shown for both experiments.

Nuclear reactions in AGB nucleosynthesis: the 19F(α, p22Ne at energies of astrophysical relevance

Directory of Open Access Journals (Sweden)

D’Agata G.

2017-01-01

Full Text Available The abundance of 19F in the universe is strictly related to standard and extra-mixing processes taking place inside AGB-stars, that are considered to be the most important sites for its production. Nevertheless the way in which it is destroyed is far from being well understood. For this reason we studied the 19F(α,p22Ne reaction, that is supposed to be the main destruction channel in the Helium-rich part of the star. In this experiment, the reaction has been studied in the energy range of relevance for astrophysics (0÷1 MeV via the Trojan Horse Method (THM, using the three-body reaction 6Li(19F,p22Ned.

Crossed Molecular Beams and Quasiclassical Trajectory Surface Hopping Studies of the Multichannel Nonadiabatic O((3)P) + Ethylene Reaction at High Collision Energy.

Science.gov (United States)

Balucani, Nadia; Leonori, Francesca; Casavecchia, Piergiorgio; Fu, Bina; Bowman, Joel M

2015-12-17

The combustion relevant O((3)P) + C2H4 reaction stands out as a prototypical multichannel nonadiabatic reaction involving both triplet and singlet potential energy surfaces (PESs), which are strongly coupled. Crossed molecular beam (CMB) scattering experiments with universal soft electron ionization mass spectrometric detection have been used to characterize the dynamics of this reaction at the relatively high collision energy Ec of 13.7 kcal/mol, attained by crossing the reactant beams at an angle of 135°. This work is a full report of the data at the highest Ec investigated for this reaction. From laboratory product angular and velocity distribution measurements, angular and translational energy distributions in the center-of-mass system have been obtained for the five observed exothermic competing reaction channels leading to H + CH2CHO, H + CH3CO, CH3 + HCO, CH2 + H2CO, and H2 + CH2CO. The product branching ratios (BRs) have been derived. The elucidation of the reaction dynamics is assisted by synergic full-dimensional quasiclassical trajectory surface-hopping calculations of the reactive differential cross sections on coupled ab initio triplet/singlet PESs. This joint experimental/theoretical study extends and complements our previous combined CMB and theoretical work at the lower collision energy of 8.4 kcal/mol. The theoretically derived BRs and extent of intersystem crossing (ISC) are compared with experimental results. In particular, the predictions of the QCT results for the three main channels (those leading to vinoxy + H, methyl + HCO and methylene + H2CO formation) are compared directly with the experimental data in the laboratory frame. Good overall agreement is noted between theory and experiment, although some small, yet significant shortcomings of the theoretical differential cross section are noted. Both experiment and theory find almost an equal contribution from the triplet and singlet surfaces to the reaction, with a clear tendency of the

Charge-exchange reactions on 36 S

International Nuclear Information System (INIS)

Fifield, L.K.; Catford, W.N.; Orr, N.A.; Ophel, T.R.; Etchegoyen, A.; Etchegoyen, M.C.

1992-11-01

A series of charge-exchange reactions on 36 S targets have been investigated at beam energies ∼7 MeV/A. Pronounced selectivities to different final states in 36 P are observed which depend on the projectile employed. An interpretation of the data in terms of one- and two-step pictures of the reaction mechanism is presented. At least two, and probably all, of the reactions have a significant 1-step contribution to the reaction mechanism at these energies. 22 refs., 5 tabs., 5 figs

Reaction product imaging

Energy Technology Data Exchange (ETDEWEB)

Chandler, D.W. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01

Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

Kinetic energy spectrum and polarization of neutrons from the reaction 12C(p,n)X at 590 MeV

International Nuclear Information System (INIS)

Arnold, J.

1998-01-01

The kinetic energy spectrum and the polarization of the PSI neutron beam produced in the reaction 12 C(p,n)X at 0 with 590 MeV polarized protons were investigated. A strong energy dependence of the neutron beam polarization is observed which was not expected at the time the neutron beam was built. (orig.)

Role of Electronic Structure In Ion Band State Theory of Low Energy Nuclear Reactions

Science.gov (United States)

Chubb, Scott

2004-03-01

The Nuts and Bolts of our Ion Band State (IBS) theory of low energy nuclear reactions (LENR's) in palladium-deuteride (PdD) and palladium-hydride (PdH) are the electrons that hold together or tear apart the bonds (or lack of bonds) between deuterons (d's) or protons (p's) and the host material. In PdDx and PdH_x, this bonding is strongly correlated with loading: in ambient loading conditions (x< 0. 6), the bonding in hibits IBS occupation. As x arrow 1, slight increases and decreases in loading can lead to vibrations (which have conventionally been thought to occur from phonons) that can induce potential losses or increases of p/d. Naive assumptions about phonons fail to include these losses and increases. These effects can occur because neither H or D has core electrons and because in either PdD or PdH, the electrons near the Fermi Energy have negligible overlap with the nucleus of either D or H. I use these ideas to develop a formal justification, based on a generalization of conventional band theory (Scott Chubb, "Semi-Classical Conduction of Charged and Neutral Particles in Finite Lattices," 2004 March Meeting."), for the idea that occupation of IBS's can occur and that this can lead to nuclear reactions.

Peripheral Ar induced reactions at 44MeV/u. Similarities and deviations with respect to a high energy fragmentation process

International Nuclear Information System (INIS)

Borrel, V.; Guerreau, D.; Galin, J.; Gatty, B.; Jacquet, D.; Tarrago, X.

1983-01-01

Peripheral Ar reactions induced on 58 Ni at GANIL at 44 MeV/u have been analyzed in the framework of the high energy fragmentation model. Several deviations from this model have been interpreted as due to the persistence of some collective effects at this intermediate energy

Understanding the reaction between muonium atoms and hydrogen molecules: zero point energy, tunnelling, and vibrational adiabaticity

Science.gov (United States)

Aldegunde, J.; Jambrina, P. G.; García, E.; Herrero, V. J.; Sáez-Rábanos, V.; Aoiz, F. J.

2013-11-01

The advent of very precise measurements of rate coefficients in reactions of muonium (Mu), the lightest hydrogen isotope, with H2 in its ground and first vibrational state and of kinetic isotope effects with respect to heavier isotopes has triggered a renewed interests in the field of muonic chemistry. The aim of the present article is to review the most recent results about the dynamics and mechanism of the reaction Mu+H2 to shed light on the importance of quantum effects such as tunnelling, the preservation of the zero point energy, and the vibrational adiabaticity. In addition to accurate quantum mechanical (QM) calculations, quasiclassical trajectories (QCT) have been run in order to check the reliability of this method for this isotopic variant. It has been found that the reaction with H2(v=0) is dominated by the high zero point energy (ZPE) of the products and that tunnelling is largely irrelevant. Accordingly, both QCT calculations that preserve the products' ZPE as well as those based on the Ring Polymer Molecular Dynamics methodology can reproduce the QM rate coefficients. However, when the hydrogen molecule is vibrationally excited, QCT calculations fail completely in the prediction of the huge vibrational enhancement of the reactivity. This failure is attributed to tunnelling, which plays a decisive role breaking the vibrational adiabaticity when v=1. By means of the analysis of the results, it can be concluded that the tunnelling takes place through the ν1=1 collinear barrier. Somehow, the tunnelling that is missing in the Mu+H2(v=0) reaction is found in Mu+H2(v=1).

A Gibbs Energy Minimization Approach for Modeling of Chemical Reactions in a Basic Oxygen Furnace

Science.gov (United States)

Kruskopf, Ari; Visuri, Ville-Valtteri

2017-12-01

In modern steelmaking, the decarburization of hot metal is converted into steel primarily in converter processes, such as the basic oxygen furnace. The objective of this work was to develop a new mathematical model for top blown steel converter, which accounts for the complex reaction equilibria in the impact zone, also known as the hot spot, as well as the associated mass and heat transport. An in-house computer code of the model has been developed in Matlab. The main assumption of the model is that all reactions take place in a specified reaction zone. The mass transfer between the reaction volume, bulk slag, and metal determine the reaction rates for the species. The thermodynamic equilibrium is calculated using the partitioning of Gibbs energy (PGE) method. The activity model for the liquid metal is the unified interaction parameter model and for the liquid slag the modified quasichemical model (MQM). The MQM was validated by calculating iso-activity lines for the liquid slag components. The PGE method together with the MQM was validated by calculating liquidus lines for solid components. The results were compared with measurements from literature. The full chemical reaction model was validated by comparing the metal and slag compositions to measurements from industrial scale converter. The predictions were found to be in good agreement with the measured values. Furthermore, the accuracy of the model was found to compare favorably with the models proposed in the literature. The real-time capability of the proposed model was confirmed in test calculations.

Mesoscale simulations of shockwave energy dissipation via chemical reactions.

Science.gov (United States)

Antillon, Edwin; Strachan, Alejandro

2015-02-28

We use a particle-based mesoscale model that incorporates chemical reactions at a coarse-grained level to study the response of materials that undergo volume-reducing chemical reactions under shockwave-loading conditions. We find that such chemical reactions can attenuate the shockwave and characterize how the parameters of the chemical model affect this behavior. The simulations show that the magnitude of the volume collapse and velocity at which the chemistry propagates are critical to weaken the shock, whereas the energetics in the reactions play only a minor role. Shock loading results in transient states where the material is away from local equilibrium and, interestingly, chemical reactions can nucleate under such non-equilibrium states. Thus, the timescales for equilibration between the various degrees of freedom in the material affect the shock-induced chemistry and its ability to attenuate the propagating shock.

Reaction-diffusion processes in zero transverse dimensions as toy models for high-energy QCD

International Nuclear Information System (INIS)

Armesto, Nestor; Bondarenko, Sergey; Quiroga-Arias, Paloma; Milhano, Jose Guilherme

2008-01-01

We examine numerically different zero-dimensional reaction-diffusion processes as candidate toy models for high-energy QCD evolution. Of the models examined-Reggeon Field Theory, Directed Percolation and Reversible Processes-only the latter shows the behaviour commonly expected, namely an increase of the scattering amplitude with increasing rapidity. Further, we find that increasing recombination terms, quantum loops and the heuristic inclusion of a running of the couplings, generically slow down the evolution.

The combined resonance tunneling and semi-resonance level in low energy D-D reaction

International Nuclear Information System (INIS)

Li Xingzhong; Jin Dezhe; Chang Lee

1993-01-01

When nuclear potential wells are connected by an atomic potential well, a new kind of tunneling may happen even if there is no virtual energy level in nuclear potential wells. The necessary condition for this combined resonance tunneling is the resonance in the atomic potential well. Thus, the nuclear reaction may be affected by the action in atomic scale in terms of combined resonance tunneling. The nuclear spectrum data support this idea. (author)

The Equilibrium and Pre-equilibrium Triton Emission Spectra of Some Target Nuclei for ( n, xt) Reactions up to 45 MeV Energy

Science.gov (United States)

Tel, E.; Kaplan, A.; Aydın, A.; Özkorucuklu, S.; Büyükuslu, H.; Yıldırım, G.

2010-08-01

Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, working out the systematics of ( n,t) reaction cross sections and triton emission differential data are important for the given reaction taking place on various nuclei at different energies. In this study, ( n,xt) reactions for some target nuclei as 16O, 27Al, 59Co and 209Bi have been investigated up to 45 MeV incident neutron energy. In the calculations of the triton emission spectra, the pre-equilibrium and equilibrium effects have been used. The calculated results have been compared with the experimental data taken from the literature.

The fluorine destruction in stars: First experimental study of the {sup 19}F(p,{alpha}){sup 16}O reaction at astrophysical energies

Energy Technology Data Exchange (ETDEWEB)

La Cognata, M.; Mukhamedzhanov, A.; Spitaleri, C.; Indelicato, I.; Aliotta, M.; Burjan, V.; Cherubini, S.; Coc, A.; Gulino, M.; Hons, Z.; Kiss, G. G.; Kroha, V.; Lamia, L.; Mrazek, J.; Palmerini, S.; Piskor, S.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S. [INFN-LNS, Catania (Italy); Cyclotron Institute, Texas A and M University, College Station, Texas (United States); University of Catania and INFN-LNS, Catania (Italy); and others

2012-11-12

The {sup 19}F(p,{alpha}){sup 16}O reaction is an important fluorine destruction channel in the proton-rich outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogendeficient post-AGB star nucleosynthesis. So far, available direct measurements do not reach the energy region of astrophysical interest (E{sub cm}{approx} 300 keV), because of the hindrance effect of the Coulomb barrier. The Trojan Horse (TH) method was thus used to access this energy region, by extracting the quasi-free contribution to the {sup 2}H({sup 19}F,{alpha}{sup 16}O)n reaction. The TH measurement of the {alpha}{sub 0} channel, which is the dominant one at such energies, shows the presence of resonant structures not observed before that cause an increase of the reaction rate at astrophysical temperatures up to a factor of 1.7, with potential important consequences for stellar nucleosynthesis.

High accuracy measurement of the $^{235}$U(n,f) reaction cross-section in the 10-30 keV neutron energy range

CERN Multimedia

The analysis of the neutron flux of n_TOF (in EAR1) revealed an anomaly in the 10-30 keV neutron energy range. While the flux extracted on the basis of the $^{6}$Li(n,t)$^{4}$He and $^{10}$B(n,$\\alpha$)$^{7}$Li reactions mostly agreed with each other and with the results of FLUKA simulations of the neutron beam, the one based on the $^{235}$U(n,f) reaction was found to be systematically lower, independently of the detection system used. A possible explanation is that the $^{235}$U(n,f) crosssection in that energy region, where in principle should be known with an uncertainty of 1%, may be systematically overestimated. Such a finding, which has a negligible influence on thermal reactors, would be important for future fast critical or subcritical reactors. Furthermore, its interest is more general, since the $^{235}$U(n,f) reaction is often used at that energy to determine the neutron flux, or as reference in measurements of fission cross section of other actinides. We propose to perform a high-accuracy, high-r...

Knock-out reactions

International Nuclear Information System (INIS)

de Forest, T. Jr.

1977-01-01

It is pointed out that the primary motivation for performing high energy single nucleon knock-out reactions is based on the concept of quasi-elastic scattering. The validity of and corrections to the partial wave impulse approximation and kinematical invariance of knock-out reactions and tests of the reaction mechanism are treated. The effect of distortions on the momentum distribution in the effective momentum approximation for given parameters are plotted. 12 references

Excitation function of ''7''4Ge(n, α)''7''1''mZn reaction in the energy range 13.82-14.70 MeV

International Nuclear Information System (INIS)

Halim, M.A.; Hafiz, M.A.; Naher, K.; Miah, R.U.; Ullah, M.R.

2003-01-01

The excitation function of the reaction ''7''4Ge(n, α)''7''1''mZn is measured by activation technique using high resolution HPGe detector gamma ray spectroscopy. Monoenergetic neutrons are produced via D-T reaction at J-25 neutron generator facility of the Institute of Nuclear Science and Technology, AERE, Bangladesh. The neutron flux measurement was done at different energy position in the range 13.82-14.70 MeV using the monitor reaction ''2''7Al(n, α)''2''4Na. The measured cross section values along with the literature data are plotted as a function of neutron energy to get the excitation function of the reaction. A theoretical calculation is also performed to produce the excitation function of the investigated reaction using statistical code SINCROS-II. The measured data are to be found to be in good agreement with the literature data and the theoretical cross section values. (author)

Tests of the GIC and Measurements of Angular Distributions and Energy Spectra for 58Ni（n,p）58Co Reaction at 4.1 MeV

Institute of Scientific and Technical Information of China (English)

Yu.M.Gledenov; M.Sedysheva; G.Khuukhenkhuu

1997-01-01

<正>On the basis of measurements of double differential cross sections for （n,α） reactions in 5-7 MeV neutron energy region using gridded ionization chamber （GIC）, we constructed a new GIC which, compared with the old ones, can bear higher pressure and makes it possible to measure （n,p） reactions up to 6 MeV and （n,xα） reactions up to 20 MeV. To test the new chamber, the saturation property for argon and krypton mixed with a few percent CO2 was studied using 241Am and compound Pu α source and tritium from 6Li(nth,t)4He, and the two dimensional spectra for 241Am and Pu α source, 6Li(nth,t)4He and H（n,p） reactions were measured. The measured energy spectra and angular distributions for α and tritium are reasonable, and the derived data for α, proton and tritium in argon and krypton from the measured spectra data were compared with the calculated ones. They are in good agreement. The angular distributions and energy spectra for 58Ni（n,p）58Co reaction at 4.1 MeV neutron energy were m

A simple approach to the solvent reorganisation Gibbs free energy in electron transfer reactions of redox metalloproteins

DEFF Research Database (Denmark)

Ulstrup, Jens

1999-01-01

We discuss a simple model for the environmental reorganisation Gibbs free energy, E-r, in electron transfer between a metalloprotein and a small reaction partner. The protein is represented as a dielectric globule with low dielectric constant, the metal centres as conducting spheres, all embedded...

Activation-energy for the reaction h+oh--]eaq- - kinetic determination of the enthalpy and entropy of solvation of the hydrated electron

DEFF Research Database (Denmark)

Hickle, B.; Sehested, Knud

1985-01-01

The reaction between atomic hydrogen and hydroxide ion in aqueous solutions H + OH- - eaq- + H20 has been studied by pulse radiolysis. The rate constant was measured at pH 11.7 and 12 by following the growth of the hydrated electron absorption at 600 nm. The activation energy of the reaction has...

Polymeric reaction of polymer-monomer system for pressure sensitive adhesives by low energy electron beam

International Nuclear Information System (INIS)

Takiguchi, R.; Uryu, T.

1985-01-01

Application of low-energy electron beam to non-solvent type pressure sensitive adhesives is investigated. The adhesive properties such as peel strength and holding time (dead-load strength) were closely related to the reaction of acrylate polymer-monomer systems. The reaction behavior is elucidated by combining the measurement of gel fraction, infrared spectrum of gel, and the molecular weight distribution detected by gel permeation chromatography. It was important for the production of pressure sensitive adhesives by electron beam that the adhesive with high peel strength and long holding time is composed of a proper combination of three factors, that is, about 35% gel fraction, 25% monomer units in gel, and 15% graft efficiency by irradiating the polymer-monomer system containing low molecular weight poly (butyl acrylate). (author)

Experimental determination of the effective nucleon-nucleon interaction for p-nucleus reactions at intermediate energies

International Nuclear Information System (INIS)

McClelland, J.B.; Aas, B.; Azizi, A.

1982-01-01

A complete measurement of the polarization transfer observables has been made for the first time in the (p,p') reaction at intermediate energies. Measurements are reported for the 12 C(p,p') 12 C reaction to the 1 + , T = 0(12.71 MeV) and 1 + , T = 1(15.11 MeV) states at 500 MeV at laboratory scattering angles of 3.5 0 , 5.5 0 , 7.5 0 , and 12.0 0 . Linear combinations of these observables are shown to exhibit a very selective dependence on the isoscalar and isovector spin-dependent components of the nucleon-nucleon interaction. To the extent of the validity of the single collision approximation, these amplitudes are compared directly to the free nucleon-nucleon amplitudes at small momentum transfers

On the detection of low-energy 4He, 12C, 14N, 16O ions in PC foils and its use in nuclear reaction measurements

International Nuclear Information System (INIS)

Somogyi, G.; Hunyadi, I.; Koltay, E.; Zolnai, L.

1977-01-01

It is shown that by using a proper etching reagent the registration sensitivity of polycarbonate foils can be enhanced and they prove to be very suitable track recorders for alpha-particles emitted from nuclear reactions. At 6 MeV an energy resolution of 0.2 MeV can be achieved when using the track diameters as a measure of the particle energy. A theoretical way to calculate the track parameters important in nuclear reaction measurements involving alpha-particles recorded in polycarbonate foils is given. For this purpose the track etch rate vs residual range curve was determined by a parameter optimization procedure. The energy resolution of the track-diameter method as a function of the particle energy was predicted. In earlier studies the track-diameter method was mostly used in angular distribution measurements of (d, α) nuclear reactions. In this work it is shown that with polycarbonate foils it can be well applied to excitation function measurements, as well. Such studies are presented for the α 0 and α 1 groups of the 27 Al(p, α) 24 Mg reaction in an energy interval between 1540 and 1920 keV. Finally, preliminary results of the track etching properties of low-energy O + , N + , C + and He + ions accelerated with a 5 MV Van de Graaff generator are given. (Auth.)

Proceedings of the Workshop on open problems in heavy ion reaction dynamics at VIVITRON energies

International Nuclear Information System (INIS)

Beck, F.A.

1993-01-01

Some problems of heavy ion reaction dynamics at the VIVITRON tandem accelerator and the experimental facilities are discussed at the meeting. Topics include light dinuclear systems, collision dynamics at low energies, fission evaporation and fusion of heavy nuclei and others. Most documents consist of transparencies presented at the workshop, texts of papers are missing. All items are indexed and abstracted for the INIS database. (K.A.)

Reaction and total cross sections for low energy π+ and π- on isospin zero nuclei

International Nuclear Information System (INIS)

Saunders, A.; Ho/ibraten, S.; Kraushaar, J.J.; Kriss, B.J.; Peterson, R.J.; Ristinen, R.A.; Brack, J.T.; Hofman, G.; Gibson, E.F.; Morris, C.L.

1996-01-01

Reaction and total cross sections for π + and π - on targets of 2 H, 6 Li, C, Al, Si, S, and Ca have been measured for beam energies from 42 to 65 MeV. The cross sections are proportional to the target mass at 50 MeV, consistent with transparency to these projectiles. The cross sections are compared to theoretical calculations. copyright 1996 The American Physical Society

Proceedings of the Workshop on open problems in heavy ion reaction dynamics at VIVITRON energies