Signature scheme for the microscopic description of nuclear collective excitations
International Nuclear Information System (INIS)
Ogawa, K.
1980-04-01
The symmetries between the proton and neutron systems in a nucleus are described in terms of the signatures. Three kinds of signatures (i.e. the pn-, p anti n- and p anti p- (or n anti n-) signatures) are introduced and they are related to the appearance of various collective motions such as rotations or vibrations. It is shown that the pn-signature scheme provides a band-like structure of deformed nuclei, while the features associated with the quadrupole vibration are obtained in the p anti n- and p anti p-signature scheme. From the detail investigation of the p anti n-symmetric wave functions, it is concluded that the reguralities provided by the present shell model are more analogous to those of the γ-unstable surface vibration model (Wilets-Jean model) than to those of harmonic phonon model. (author)
International Nuclear Information System (INIS)
Okuducu, S.; Sarac, H.; Akti, N. N.; Boeluekdemir, M. H.; Tel, E.
2010-01-01
In this study the nuclear energy level density based on nuclear collective excitation mechanism has been identified in terms of the low-lying collective level bands at near the neutron binding energy. Nuclear level density parameters of some light deformed medical radionuclides used widely in medical applications have been calculated by using different collective excitation modes of observed nuclear spectra. The calculated parameters have been used successfully in estimation of the neutron-capture cross section basic data for the production of new medical radionuclides. The investigated radionuclides have been considered in the region of mass number 40< A< 100. The method used in the present work assumes equidistance spacing of the collective coupled state bands of the interest radionuclides. The present calculated results have been compared with the compiled values from the literatures for s-wave neutron resonance data.
Sound-like collective mode excitation with pion absorption in nuclear matter
International Nuclear Information System (INIS)
Qiu Xijiun; Shen Jianguo; Huang Lingfang
1985-01-01
The relativistic mean field theory consistent with bulk properties of nuclear matter is extended to study the excitations of the sound-like collective modes in nuclear matter. Corresponding relativistic mean field equations are solved numerically and self-consistently. The effective mass of nucleon, the speed of the sound and the amplitude of the sound-like solution are calculated. When the nuclear density is near or greater than the saturation density, the sound-like non-trivial solution could be found
International Nuclear Information System (INIS)
Rodrigues, C.L.; Rodrigues, M.R.D.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J. L.M.; Hanninger, G.N.; Ukita, G.M.
2004-01-01
The study of the odd 99,101 Ru nuclei complements the investigation of the collectivity of the first quadrupolar excitations in 100,102,104 Ru. Angular distributions for the 99,101 Ru(d, d') reactions at 13 MeV were obtained in the Pelletron Laboratory using nuclear emulsion plates on the focal plane of the Enge spectrograph. A Coulomb- Nuclear Interference analysis employing DWBA-DOMP predictions with global optical potential parameters was applied to the excitation of states which could belong to the multiplet built on the first quadrupolar excitation of the core. In the analysis, three states were identified for each of the isotopes and associated, respectively, with adopted levels in the Nuclear Data Sheets Compilation of Jπ = 5=2 + , 7=2 + and 9=2 + . Through the comparison of experimental and predicted cross section angular distributions, the values of (δ L N ) 2 and of the ratio C = δ L C /δ L N were obtained. (author)
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, C.L.; Rodrigues, M.R.D.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J. L.M.; Hanninger, G.N. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Ukita, G.M. [Universidade de Santo Amaro, SP (Brazil). Faculdade de Psicologia
2004-09-15
The study of the odd {sup 99,101}Ru nuclei complements the investigation of the collectivity of the first quadrupolar excitations in {sup 100,102,104}Ru. Angular distributions for the {sup 99,101}Ru(d, d') reactions at 13 MeV were obtained in the Pelletron Laboratory using nuclear emulsion plates on the focal plane of the Enge spectrograph. A Coulomb- Nuclear Interference analysis employing DWBA-DOMP predictions with global optical potential parameters was applied to the excitation of states which could belong to the multiplet built on the first quadrupolar excitation of the core. In the analysis, three states were identified for each of the isotopes and associated, respectively, with adopted levels in the Nuclear Data Sheets Compilation of J{pi} = 5=2{sup +}, 7=2{sup +} and 9=2{sup +}. Through the comparison of experimental and predicted cross section angular distributions, the values of ({delta}{sup L}{sub N}){sup 2} and of the ratio C = {delta}{sub L}{sup C} /{delta}{sub L}{sup N} were obtained. (author)
High energy nuclear excitations
International Nuclear Information System (INIS)
Gogny, D.; Decharge, J.
1983-09-01
The main purpose of this talk is to see whether a simple description of the nuclear excitations permits one to characterize some of the high energy structures recently observed. The discussion is based on the linear response to different external fields calculated using the Random Phase Approximation. For those structure in heavy ion collisions at excitation energies above 50 MeV which cannot be explained with such a simple approach, we discuss a possible mechanism for this heavy ion scattering
Microscopic approach in Inelastic Heavy-Ions Scattering with Excitation of Nuclear Collective States
International Nuclear Information System (INIS)
Lukyanov, K.V.; Zemlyanya, E.V.; Khtina, I.N.; Lukyanov, V.K; Metawe, Z.; Hanna, K.M.
2008-01-01
In the density distribution of a deformed target-nucleus,the spherical λ = 0 and the deformed λ = 2 parts were considered. On this basis, the corresponding potential parts U 0 and U i nt(2) of a double-folding microscopic nucleus-nucleus optical potential are obtained. Then, for these potentials and by using the coupled- channel technique (ECIS), the elastic and inelastic amplitudes are calculated for 17 O heavy ions scattering on 2 + collective excited stat of various target nuclei. Besides,the same cross-sections are calculated in the frame of an adiabatic approach of the eikonal approximation, where the inelastic amplitude is the linear function of U i nt (2).Both the obtained results are compared with the experimental data, and also discus their efficiency in predicting the deformation parameters of nuclei
Nuclear spin and isospin excitations
International Nuclear Information System (INIS)
Osterfeld, F.
1992-01-01
A review is given of our present knowledge of collective spin-isospin excitations in nuclei. Most of this knowledge comes from intermediate-energy charge-exchange reactions and from inelastic electron- and proton-scattering experiments. The nuclear-spin dynamics is governed by the spin-isospin-dependent two-nucleon interaction in the medium. This interaction gives rise to collective spin modes such as the giant Gamow-Teller resonances. An interesting phenomenon is that the measured total Gamow-Teller transition strength in the resonance region is much less than a model-independent sum rule predicts. Two physically different mechanisms have been discussed to explain this so-called quenching of the total Gamow-Teller strength: coupling to subnuclear degrees of freedom in the form of Δ-isobar excitation and ordinary nuclear configuration mixing. Both detailed nuclear structure calculations and extensive analyses of the scattering data suggest that the nuclear configuration mixing effect is the more important quenching mechanism, although subnuclear degrees of freedom cannot be ruled out. The quenching phenomenon occurs for nuclear-spin excitations at low excitation energies (ω∼10--20 MeV) and small-momentum transfers (q≤0.5 fm -1 ). A completely opposite effect is anticipated in the high (ω,q)-transfer region (0≤ω≤500 MeV, 0.5≤q≤3 fm -1 ). The nuclear spin-isospin response might be enhanced due to the attractive pion field inside the nucleus. Charge-exchange reactions at GeV incident energies have been used to study the quasifree peak region and the Δ-resonance region. An interesting result of these experiments is that the Δ excitation in the nucleus is shifted downwards in energy relative to the Δ excitation of the free proton
Pancholi, S C
2011-01-01
By providing the reader with a foundational background in high spin nuclear structure physics and exploring exciting current discoveries in the field, this book presents new phenomena in a clear and compelling way. The quest for achieving the highest spin states has resulted in some remarkable successes which this monograph will address in comprehensive detail. The text covers an array of pertinent subject matter, including the rotational alignment and bandcrossings, magnetic rotation, triaxial strong deformation and wobbling motion and chirality in nuclei. Dr. Pancholi offers his readers a clearly-written and up-to-date treatment of the topics covered. The prerequisites for a proper appreciation are courses in nuclear physics and nuclear models and measurement techniques of observables like gamma-ray energies, intensities, multi-fold coincidences, angular correlations or distributions, linear polarization, internal conversion coefficients, short lifetime (pico-second range) of excited states etc. and instrum...
Collective nuclear dynamics. Proceedings
International Nuclear Information System (INIS)
Ivanyuk, F.A.
1994-01-01
The Fourth International school on nuclear physics was help on 29 Aug - 7 Sep, 1994 in Ukraine. The specialists discussed following subjects:liquid drop and the shell correction method; nuclear deformation energy and fission; nuclear structure at high spins, superdeformed states, structure of excited and exotic nuclei; nuclear fluid dynamics and large scale collective motion; order and chaos as they relate to the collective motion; quantum and interference phenomena in nuclear collisions; quasi-fission and multinucleon fragmentation effects; shell effects in non-nuclear systems; new nuclear facilities
Collective nuclear dynamics. Abstracts
International Nuclear Information System (INIS)
Abrosimov, V.I.; Kolomietz, V.M.
1994-01-01
The fourth International school on nuclear physics was help on 29 Aug - 7 Sep, 1994 in Ukraine. The specialists discussed following subjects: liquid drop and the shell correction method; nuclear deformation energy and fission; nuclear structure at high spins, superdeformed states, structure of excited and exotic nuclei; nuclear fluid dynamics and large scale collective motion; order and chaos as they relate to the collective motion; quantum and interference phenomena in nuclear collisions; quasi-fission and multinucleon fragmentation effects; shell effects in non-nuclear systems; new nuclear facilities
Collective nuclear dynamics. Proceedings.
Energy Technology Data Exchange (ETDEWEB)
Ivanyuk, F A [eds.
1994-12-31
The Fourth International school on nuclear physics was help on 29 Aug - 7 Sep, 1994 in Ukraine. The specialists discussed following subjects:liquid drop and the shell correction method; nuclear deformation energy and fission; nuclear structure at high spins, superdeformed states, structure of excited and exotic nuclei; nuclear fluid dynamics and large scale collective motion; order and chaos as they relate to the collective motion; quantum and interference phenomena in nuclear collisions; quasi-fission and multinucleon fragmentation effects; shell effects in non-nuclear systems; new nuclear facilities.
Collective nuclear excitations with Skyrme-second random-phase approximation
International Nuclear Information System (INIS)
Gambacurta, D.; Catara, F.; Grasso, M.
2010-01-01
Second random-phase approximation (RPA) calculations with a Skyrme force are performed to describe both high- and low-lying excited states in 16 O. The coupling between one particle-one hole and two particle-two hole as well as that between two particle-two hole configurations among themselves are fully taken into account, and the residual interaction is never neglected; we do not resort therefore to a generally used approximate scheme where only the first kind of coupling is considered. The issue of the rearrangement terms in the matrix elements beyond the standard RPA will be considered in detail in a forthcoming paper. Two approximations are employed here for these rearrangement terms: they are either neglected or evaluated with the RPA procedure. As a general feature of second RPA results, a several-MeV shift of the strength distribution to lower energies is systematically found with respect to RPA distributions. A much more important fragmentation of the strength is also naturally provided by the second RPA owing to the huge number of two particle-two hole configurations. A better description of the excitation energies of the low-lying 0 + and 2 + states is obtained with the second RPA than with the RPA.
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1998-01-01
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors)
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)
1998-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors) 304 refs., 53 figs., 5 tabs.
Competition between collective and single particle excitations in nuclear structure description
International Nuclear Information System (INIS)
Petrovici, A.N.
1983-01-01
The microscopic description of the quadrupole collective dynamics in even krypton isotopes is presented. A microscopic calculation of Bohr's collective Hamiltonian is used to describe the collective motion in 76 Kr. A single-particle basis calculated in a deformed Woods-Saxon potential leads to the potential energy surface obtained by the Strutinsky renormalization procedure, and to the inertial functions determined in the cranking model approximation. The collective Schroedinger equation is solved numerically to analyse the low-energy, even parity states in 76 Kr. A good agreement between experiment and theory is obtained without specifically adjusting any parameter in the model for this nucleus. Some results regarding statical and dynamical characteristics of sup(74,78,80)Kr isotopes are also presented. The asymmetric rotor model with admixture of two quasiparticles is used to describe the sup(66,68,70)Ge and the sup(64,66)Zn isotopes. The interplay of collective and single particle motions is further investigated by magnetic moment measurements using the method of integral angular correlations perturbed by recoil into gas. The results involve g-factor measurements for 166 Ho, 68 Ge, 64 Zn, 66 Zn and 68 Ga nuclei. Finally, a discussion of further possible improvements and more general developments of the problems under investigation is given. (author)
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1997-01-01
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author)
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph
1997-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author) 270 refs.
International Nuclear Information System (INIS)
Soukhovitskii, Efrem Sh.; Morogovskii, Gennadij B.; Chiba, Satoshi; Iwamoto, Osamu; Fukahori, Tokio
2004-03-01
This report gives a detailed description of the theory and computational algorithms of modernized coupled-channels optical model code OPTMAN based on the soft-rotator model for the collective nuclear structure and excitations. This work was performed under the Project Agreement B-521 with the International Science and Technology Center (Moscow), financing party of which is Japan. As a result of this work, the computational method of OPTMAN was totally updated, and an user-friendly interface was attached. (author)
Nuclear excitation in muonic gold
Robert Tissot, B; Debrunner, P; Engfer, R; Link, R; Schellenberg, L; Schneuwly, H; Walter, H K
1973-01-01
Energies and intensities of muonic X-rays in gold were measured at the CERN muon channel with an experimental set-up as described by Backe et al. (1972). The 2p-1s and 3d-2p transitions could only be analysed taking into account beside the static quadrupole interaction a dynamical hyperfine interaction of the 2p states, which leads to an excitation of the first four nuclear levels. The dynamical hyperfine interaction was calculated using the core excitation model (de Shalit, (1961)). (0 refs).
Nuclear excited power generation system
International Nuclear Information System (INIS)
Parker, R.Z.; Cox, J.D.
1989-01-01
A power generation system is described, comprising: a gaseous core nuclear reactor; means for passing helium through the reactor, the helium being excited and forming alpha particles by high frequency radiation from the core of the gaseous core nuclear reactor; a reaction chamber; means for coupling chlorine and hydrogen to the reaction chamber, the helium and alpha particles energizing the chlorine and hydrogen to form a high temperature, high pressure hydrogen chloride plasma; means for converting the plasma to electromechanical energy; means for coupling the helium back to the gaseous core nuclear reactor; and means for disassociating the hydrogen chloride to form molecular hydrogen and chlorine, to be coupled back to the reaction chamber in a closed loop. The patent also describes a power generation system comprising: a gaseous core nuclear reactor; means for passing hydrogen through the reactor, the hydrogen being excited by high frequency radiation from the core; means for coupling chlorine to a reaction chamber, the hydrogen energizing the chlorine in the chamber to form a high temperature, high pressure hydrogen chloride plasma; means for converting the plasma to electromechanical energy; means for disassociating the hydrogen chloride to form molecular hydrogen and chlorine, and means for coupling the hydrogen back to the gaseous core nuclear reactor in a closed loop
International Nuclear Information System (INIS)
Wu, Hua.
1989-01-01
One of the most elusive quantum system in nature is the nucleus, which is a strongly interacting many body system. In the hadronic (a la neutrons and protons) phase, the primary concern of this thesis, the nucleus' single particle excitations are intertwined with their various collective excitations. Although the underpinning of the nucleus is the spherical shell model, it is rendered powerless without a severe, but intelligent truncation of the infinite Hilbert space. The recently proposed Fermion Dynamical Symmetry Model (FDSM) is precisely such a truncation scheme and in which a symmetry-dictated truncation scheme is introduced in nuclear physics for the first time. In this thesis, extensions and explorations of the FDSM are made to specifically study the odd mass (where the most intricate mixing of the single particle and the collective excitations are observed) and the neutron-proton systems. In particular, the author finds that the previously successful phenomenological particle-rotor-model of the Copenhagen school can now be well understood microscopically via the FDSM. Furthermore, the well known Coriolis attenuation and variable moment of inertia effects are naturally understood from the model as well. A computer code FDUO was written by one of us to study, for the first time, the numerical implications of the FDSM. Several collective modes were found even when the system does not admit a group chain description. In addition, the code is most suitable to study the connection between level statistical behavior (a at Gaussian Orthogonal Ensemble) and dynamical symmetry. It is found that there exist critical region of the interaction parameter space were the system behaves chaotically. This information is certainly crucial to understanding quantum chaotic behavior
Nuclear transitions induced by atomic excitations
International Nuclear Information System (INIS)
Dyer, P.; Bounds, J.A.; Haight, R.C.; Luk, T.S.
1988-01-01
In the two-step pumping scheme for a gamma-ray laser, an essential step is that of exciting the nucleus from a long-lived storage isomer to a nearby short- lived state that then decays to the upper lasing level. An experiment is in progress to induce this transfer by first exciting the atomic electrons with UV photons. The incident photons couple well to the electrons, which then couple via a virtual photon to the nucleus. As a test case, excitation of the 235 U nucleus is being sought, using a high- brightness UV laser. The excited nuclear state, having a 26- minute half-life, decays by internal conversion, resulting in emission of an atomic electron. A pulsed infrared laser produces an atomic beam of 235 U which is then bombarded by the UV laser beam. Ions are collected, and conversion electrons are detected by a channel electron multiplier. In preliminary experiments, an upper limit of 7 x 10 -5 has been obtained for the probability of exciting a 235 U atom in the UV beam for one picosecond at an intensity of about 10 15 W/cm 2 . Experiments with higher sensitivities and at higher UV beam intensities are underway
Nuclear excitations and reaction mechanisms
International Nuclear Information System (INIS)
Fallieros, S.; Levin, F.S.
1990-01-01
The main theme of this report is the study and interpretation of the sequence of events that occur during the collisions of nuclear particles. Some of the processes discussed in parts A and B involve short range interactions; others involve interactions of long range. In most of part A one of the particles in the initial or in the final state (or in both) is a photon, which serves as a probe of the second particle, which may be a nucleus, a proton, a pion or any other hadron. The complexity of the processes taking place during the collisions makes it necessary to simplify some aspects of the physical problem. This leads to the introduction of modals which are used to describe a limited number of features in as much detail as possible. The main interest is the understanding of the hadronic excitations which result from the absorption of a photon and the determination of the fundamental structure constants of the target particle. In part B, all the particles are hadrons. The purpose here is to develop and apply optimal quantal methods appropriate for describing the interacting systems. Of particular interest are three-particle collision systems in which the final state consists of three free particles. Part B also considers the process of nuclear fusion as catalyzed by bound muons
Macroscopic dynamics of thermal nuclear excitations
International Nuclear Information System (INIS)
Bastrukov, S.I.; Deak, F.; Kiss, A.; Seres, Z.
1989-11-01
The concept of kinetic temperature as a local dynamical variable of thermal nuclear collective motion is formulated using long-mean-free-path approach based on the Landau-Vlasov kinetic equation. In the Fermi drop model the thermal fluid dynamics of the spherical nucleus is analyzed. It is shown that in a compressible Fermi liquid the temperature pulses propagate in the form of spherical wave in phase with the acoustic wave. The thermal and compressional excitations are caused by the isotropic harmonic oscillations of the Fermi sphere in momentum space. (author) 25 refs.; 2 figs
Nuclear wobbling-phonon excitations with alignments
International Nuclear Information System (INIS)
Hamamoto, I.
2003-01-01
Wobbling-phonon excitations, which are recently observed in 71 163 Lu 92 , are studied. The presence of alignments in nuclei makes it easier for wobbling excitations to appear at lower angular momenta of the yrast spectra. A family of rotational bands with wobbling excitations, which have nearly the same nuclear intrinsic structure, have been pinned down by observing specific electromagnetic decay properties between them. The triaxiality parameter γ = +20 deg. is obtained for the nuclear shape from measured E2 transition probabilities
Theory of nuclear excitation by electron capture for heavy ions
International Nuclear Information System (INIS)
Palffy, Adriana; Scheid, Werner; Harman, Zoltan
2006-01-01
We investigate the resonant process of nuclear excitation by electron capture (NEEC), in which a continuum electron is captured into a bound state of an ion with the simultaneous excitation of the nucleus. In order to derive the cross section a Feshbach projection operator formalism is introduced. Nuclear states and transitions are described by a nuclear collective model and making use of experimental data. Transition rates and total cross sections for NEEC followed by the radiative decay of the excited nucleus are calculated for various heavy-ion collision systems
Collective excitations in deformed alkali metal clusters
International Nuclear Information System (INIS)
Lipparini, E.; Stringari, S.; Istituto Nazionale di Fisica Nucleare, Povo
1991-01-01
A theoretical study of collective excitations in deformed metal clusters is presented. Sum rules are used to study the splittings of the dipole surface plasma resonance originating from the cluster deformation. The vibrating potential model is developed and used to predict the occurrence of a low lying collective mode of orbital magnetic nature. (orig.)
Collective Quadrupole Excitations of Transactinide Nuclei
Zajac, K; Pomorski, K; Rohozinski, S G; Srebrny, J
2003-01-01
The quadrupole excitations of transuranic nuclei are described in the frame of the microscopic Bohr Hamiltonian modified by adding the coupling with the collective pairing vibrations. The energies of the states from the ground-state bands in U to No even-even isotopes as well as the B(E2) transition probabilities are reproduced within the model containing no adjustable parameters.
Collective excitations of harmonically trapped ideal gases
Van Schaeybroeck, B.; Lazarides, A.
2009-01-01
We theoretically study the collective excitations of an ideal gas confined in an isotropic harmonic trap. We give an exact solution to the Boltzmann-Vlasov equation; as expected for a single-component system, the associated mode frequencies are integer multiples of the trapping frequency. We show
Collective excitations in itinerant spiral magnets
International Nuclear Information System (INIS)
Kampf, A.P.
1996-01-01
We investigate the coupled charge and spin collective excitations in the spiral phases of the two-dimensional Hubbard model using a generalized random-phase approximation. Already for small doping the spin-wave excitations are strongly renormalized due to low-energy particle-hole excitations. Besides the three Goldstone modes of the spiral state the dynamical susceptibility reveals an extra zero mode for low doping and strong coupling values signaling an intrinsic instability of the homogeneous spiral state. In addition, near-zero modes are found in the vicinity of the spiral pitch wave number for out-of-plane spin fluctuations. Their origin is found to be the near degeneracy with staggered noncoplanar spiral states which, however, are not the lowest energy Hartree-Fock solutions among the homogeneous spiral states. copyright 1996 The American Physical Society
Quadrupole collective excitations in rapidly rotating nuclej
International Nuclear Information System (INIS)
Mikhajlov, I.N.
1983-01-01
The spectrum of collective quadrupole excitations in nuclei is investigated. The average nucleus field has the axial symmetry and rotation occurs relatively to this axis. Dependences of the spectrum of quadrupole oscillations on rotation rate for classic liquid drop (CLD) and for a drop of fermi-liquid (DFL) with fissionability parameter X=0.62 ( 154 Er) are presented. The dependence of probabilities of E2-transitions between single-phonon and phonon-free states on rotation rate for CLD and DFL with fussionability parameter X=0.62 ( 154 Er) is also presented. It is shown that for CLD collective E2-transition of states of yrast-consequence is absolutely forbidden. For DFL transitions are possible that lead to decay of phonon-free state with the excitation of phonons of γ-modes and decrease of angular momentum
Influence of collective excitations on preequilibrium and equilibrium processes
International Nuclear Information System (INIS)
Ignatyuk, A.V.; Lunev, V.P.
1991-01-01
In all models used for calculations of nuclear cross sections, the reaction mechanisms are separated into one-step and multistep direct, multistep compound, preequilibrium and compound equilibrium. However, essential variances in estimates of the direct and preequilibrium process contributions still exist. This paper presents a demonstration of the connection of these variances with the influence of collective excitations on the direct and compound processes. (author). 13 refs, 8 figs
Nuclear excitations in the nuclear response theory
International Nuclear Information System (INIS)
Nguyen Van Giai.
1983-01-01
The Random Phase Approximation is used to calculate the response of a nucleus to an external field. The method allows a full treatment of continuum effects. Effective interactions to be used are discussed, and the consistency between the mean field and the residual interaction is stressed. Some applications to excitation properties of spherical nuclei are shown
Table of Half-Lives for Excited Nuclear Levels
Energy Technology Data Exchange (ETDEWEB)
Malmskog, S G
1970-07-15
The knowledge of the half-lives of excited states is often a valuable information in the investigation of the nuclear level structure. The present paper contains a collection of such half-lives being published in the current literature over the period 1967-1970. The data is arranged in increasing order of mass number.
Nuclear excitations and reaction mechanisms
International Nuclear Information System (INIS)
Fallieros, S.; Levin, F.S.
1989-01-01
This Progress Report describes the work of the Brown University Nuclear Theory Group for the period 1 August 1988--31 July 1989 under Grant FG02-87ER40334. Completed and on-going research includes various theoretical and numerical studies on: virtual photons, electric polarizability, the Cabibo-Radicati sum rule, photon scattering, electron scattering, electron scattering sum rules, muon catalyzed fusion, few body collisions and breakup phenomena. Since it accompanies the three-year Renewal Proposal of the Group, it goes into more detail than our typical one-year reports
Collective excitation spectra of transitional even nuclei
International Nuclear Information System (INIS)
Quentin, P.; Paris-11 Univ., 91 - Orsay; Deloncle, I.; Libert, J.; Sauvage, J.
1990-01-01
This talk is dealing with the nuclear low energy collective motion as described in the context of microscopic versions of the Bohr Hamiltonian. Two different ways of building microscopically Bohr collective Hamiltonians will be sketched; one within the framework of the Generator Coordinate Method, the other using the Adiabatic Time-Dependent Hartree-Fock-Boholyubov approximation. A sample of recent results will be presented which pertains to the description of transitional even nuclei and to the newly revisited phenomenon of superdeformation at low spin
Electron scattering and collective excitations in nuclei
International Nuclear Information System (INIS)
Goutte, D.
1989-01-01
Nuclear collective degrees of freedom are investigated through the study of the radial dependance of their wave function. Inelastic electron scattering is shown to be the appropriate tool to extract such a detailed information. Some recent results on spherical as well as deformed nuclei are discussed and the most recent extensions to the mean field approach are compared to these data in order to clarify the present status of our understanding of the dynamical properties of complex nuclei
Nuclear Excitations by Antiprotons and Antiprotonic Atoms
2002-01-01
The proposal aims at the investigation of nuclear excitations following the absorption and annihilation of stopped antiprotons in heavier nuclei and at the same time at the study of the properties of antiprotonic atoms. The experimental arrangement will consist of a scintillation counter telescope for the low momentum antiproton beam from LEAR, a beam degrader, a pion multiplicity counter, a monoisotopic target and Ge detectors for radiation and charged particles. The data are stored by an on-line computer.\\\\ \\\\ The Ge detectors register antiprotonic x-rays and nuclear @g-rays which are used to identify the residual nucleus and its excitation and spin state. Coincidences between the two detectors will indicate from which quantum state the antiprotons are absorbed and to which nuclear states the various reactions are leading. The measured pion multiplicity characterizes the annihilation process. Ge&hyphn. and Si-telescopes identify charged particles and determine their energies.\\\\ \\\\ The experiment will gi...
Collective electronic excitations in C60 crystals
International Nuclear Information System (INIS)
Wu, X.; Ulloa, S.E.
1994-01-01
We present a theoretical study of the electronic excitations in fullerene crystals by calculating the density-density correlation function in a fully nonlocal linear response theory. Our results indicate that the collective features associates with the π→π * transitions show strong anisotropic properties, with peaks changing by as much as 0.7 eV in different directions. Meanwhile, the calculated mode dispersion exhibits rather weak wave-number dependence along a given direction, in general agreement with experimental results. The oscillator strength also shows anisotropic behavior, with significant weight redistribution for different directions. We also analyze this system in terms of a classical point-dipole array model, and show that this simple model approximates well the quantum results
Prospects for coherently driven nuclear radiation by Coulomb excitation
International Nuclear Information System (INIS)
Karamyan, S.A.; Carroll, J.J.
2006-01-01
Possible experiments are discussed in which the Coulomb excitation of nuclear isomers would be followed by sequential energy release. The possibility of the coherent Coulomb excitation of nuclei ensconced in a crystal by channeled relativistic heavy projectiles is considered. The phase shift between neighbor-nuclei excitations can be identical to the photon phase shift for emission in forward direction. Thus, the elementary string of atoms can radiate coherently with emission of characteristic nuclear γ rays and the intensity of the radiation could be increased due to the summation of amplitudes. The Moessbauer conditions should be important for this new type of collective radiation that could be promising in the context of the γ-lasing problem
Collective density excitations in liquid sodium
International Nuclear Information System (INIS)
Sharma, R.K.; Tankeshwar, K.; Moudgil, R.K.
1997-11-01
The dynamical structure factor S(q, ω) and first order memory function of liquid sodium near its triple point is studied by using the Mori's memory function formalism. The memory function has been evaluated self-consistently by expressing the third stage memory function in terms of scaled second order memory function. The short time properties of S(q, ω) are exactly incorporated by the use of frequency sum rules while the long time property is fixed by the scaling parameter. The scaled parameter is determined from the zero frequency dynamical structure factor. For the interaction between the ions we have used the effective pair potential based on pseudopotential theory. It is found that for q ≤ 1.16A 0-1 our method predicts the collective density excitation peak in S(q, ω) in agreement with the molecular dynamics data. For q = 1.99A 0-1 no such peak is observed at finite w which is again in agreement with molecular dynamics data, but for q = 2.74A 0-1 we again observed a shoulder. The results for the first order memory function have also been compared with the molecular dynamics data and a good agreement is obtained at short times. (author)
Excitation of nuclear states by synchrotron radiation
International Nuclear Information System (INIS)
Olariu, Albert
2003-01-01
We study the excitation of nuclear states by gamma ray beams of energy up to 200 keV produced as synchrotron radiation. We consider the possibility to populate an excited state |i> in two steps, from the ground state |g> to an intermediary state |n> which decays by gamma emission or internal conversion to a lower state |i>. The aim of this study is to establish that the probability P 2 of the two-step transition |g> → |n> → |i> should be greater than the probability P 1 of the direct transition |g> → |i>. The probabilities P 1 and P 2 correspond to a radiation pulse of duration equal to the half-time of the state |i>. We have written a computer program in C++ which computes the probability P 2 , the ratio P 2 /P 1 and the rate C 2 of the two-step transitions for any nuclei and different configurations of states. The program uses a database which contains information on the energy levels, half-lives, spins and parities of nuclear states and on the relative intensities of the nuclear transitions. If the half-lives or the relative intensities are not known the program uses the Weisskopf estimates for the transition half-lives. An interpolation program of internal conversion coefficients has also been used. We listed the values obtained for P 2 , P 2 /P 1 and C 2 in a number of cases in which P 2 is significant from the 2900 considered cases. The states |i> and |n> have the energies E i and E n , the corresponding half-lives being t i and t n . The spectral density of the synchrotron radiation has been considered to be 10 12 photons cm -2 s -1 eV -1 . We listed only the cases for which the relative intensities of the transitions from levels |n> and |i> to lower states are known. The calculations carried out in this study allowed us to identify nuclei for which P 2 has relatively great values. In the listed cases P 2 /P 1 >>1, so that the two-step excitation by synchrotron radiation is more efficient than the direct excitation |g> → |i>. For a sample having 10
International Nuclear Information System (INIS)
Nagano, K.; Aoki, Y.; Kishimoto, T.; Yagi, K.
1983-01-01
Vector analyzing powers A(theta) and differential cross sections σ(theta) have been measured, with the use of a polarized proton beam of 22.0 MeV and a magnetic spectrograph, for (p,t) reactions leading to the first-excited 2 + (2 1 + ) states of the following eighteen nuclei of N = 50 - 82: sup(92,94,96)Mo, sup(98,100,102)Ru, sup(102,104,106,108)Pd, sup(110,112,114)Cd, 116 Sn, sup(120,126,128)Te, and 136 Ba. In addition A(theta) and σ(theta) for sup(104,110)Pd(p,t) sup(102,108) Pd(0sub(g) + ,2 1 + ) transitions have been measured at Esub(p) = 52.2 MeV. The experimental results are analyzed in terms of the first- and second-order DWBA including both inelastic two-step processes and sequential transfer (p,d)(d,t) two-step processes. Inter-ference effect between the direct and the two-step processes is found to play an essential role in the (p,t) reactions. A sum-rule method for calculating the (p,d)(d,t) spectroscopic amplitudes has been developed so as to take into account the ground-state correlation in odd-A nuclei. The nuclear-structure wave functions are constructed under the boson expansion method and the quasiparticle random phase approximation (qp RPA) method by using the monopole-pairing, quadrupole-pairing, and QQ forces. The characteristic features of the experimental A(theta) and σ(theta) are better explained in terms of the boson expansion method than in terms of the qp RPA. Dependence of the (p,t) analyzing powers on the static electric quadrupole moment of the 2 1 + state is found to be strong because of the reorientation (anharmonic) effect in the 2 1 + yiedls 2 1 + transfer process. (J.P.N.)
Probability of collective excited state decay
International Nuclear Information System (INIS)
Manykin, Eh.A.; Ozhovan, M.I.; Poluehktov, P.P.
1987-01-01
Decay mechanisms of condensed excited state formed of highly excited (Rydberg) atoms are considered, i.e. stability of so-called Rydberg substance is analyzed. It is shown that Auger recombination and radiation transitions are the basic processes. The corresponding probabilities are calculated and compared. It is ascertained that the ''Rydberg substance'' possesses macroscopic lifetime (several seconds) and in a sense it is metastable
Fragment emission from modestly excited nuclear systems
Energy Technology Data Exchange (ETDEWEB)
Lou, Y. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Souza, R.T. de [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Chen, S.L. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Cornell, E.W. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Davin, B. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Fox, D. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Hamilton, T.M. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Mcdonald, K. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Tsang, M.B. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Glasmacher, T. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Dinius, J. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Gelbke, C.K. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Handzy, D.O. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility]|[Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Hsi, W.C.
1996-07-08
Fragment emission patterns occurring in nuclear systems of modest excitation are studied. Exclusive measurement of fragment emission in {sup 14}N+{sup 197}Au reactions at E/A=100, 130 and 156 MeV allows selection of central collisions where a single source dominates the decay. Low threshold measurement of IMF emission for these events allows investigation of the influence of detector threshold effects. The time scale of fragment emission is deduced using fragment-fragment velocity correlations. Comparisons are made to the predictions of a statistical decay model. (orig.).
Nuclear reactions excited by recoil protons on a nuclear reactor
International Nuclear Information System (INIS)
Mukhammedov, S.; Khaydarov, A.; Barsukova, E.G.
2006-01-01
The nuclear reactions excited by recoil protons and of the detection possibility of the various chemical elements with the use of these secondary nucleus reactions were investigated. The recoil protons are produced on a nuclear reactor in the result of (n, p) inelastic and elastic scattering interaction of fast neutrons with nuclei of hydrogen. It is well known that the share of fast neutrons in energetic spectrum of reactor's neutrons in comparison with the share of thermal neutrons is small. . Consequently, the share of recoil protons produced in the result of fast neutron interaction with nuclei of light elements, capable to cause the nuclear reactions, is also small, des, due to Coulomb barrier of nuclei the recoil protons can cause the nuclear reactions only on nuclei of light and some middle elements. Our studies show that observable yields have radio nuclides excited in the result of nuclear reactions on Li, B, O, V and Cu. Our experimental results have demonstrated that the proton activation analysis based on the application of secondary nuclear reactions is useful technique to determine large contents of various light and medium chemical elements. Detection limits for studied chemical elements are estimated better than 10 ppm
Calculation of nuclear excitation in an electron transition
Energy Technology Data Exchange (ETDEWEB)
Pisk, K. (Institut Rudjer Boskovic, Zagreb (Yugoslavia)); Kaliman, Z. (Rijeka Univ. (Yugoslavia). Faculty of Pedagogics); Logan, B.A. (Ottawa Univ., ON (Canada). Ottawa-Carleton Centre for Physics)
1989-11-06
We have made a theoretical investigation of nuclear excitation during an electron transition (NEET). Our approach allows us to express the NEET probabilities in terms of the excited nuclear level width, the energy difference between the nuclear and electron transition, the Coulomb interaction between the initial electron states, and the electron level width. A comparison is made with the available experimental results. (orig.).
Search for nuclear excitation by laser-driven electron motion
International Nuclear Information System (INIS)
Bounds, J.A.; Dyer, P.
1992-01-01
It has been proposed that a nucleus may be excited by first exciting the atom's electrons with UV photons. The incident photons couple to the electrons, which would then couple via a virtual photon to the nucleus. As a test case, experiments with 235 U have been performed. A pulsed infrared laser produces an atomic vapor of 235 U which is then bombarded by a high-brightness UV laser beam. The resulting ions are collected. The first excited nuclear state of 235 U has a 26-min half-life and decays by internal conversion, resulting in emission of an atomic electron. These conversion electrons are detected by a channel electron multiplier. An upper limit of 4.0x10 -5 has been obtained for the probability of exciting the nucleus of a 235 U atom that is in the 248-nm UV beam for 700 fs at an irradiance in the range of 1.0x10 15 to 2.5x10 15 W/cm 2
Collective excitations in unconventional superconductors and superfluids
Brusov, Peter
2009-01-01
This is the first monograph that strives to give a complete and detailed description of the collective modes (CMs) in unconventional superfluids and superconductors (UCSF&SC). Using the most powerful method of modern theoretical physics - the path (functional) integral technique - authors build the three- and two-dimensional models for s -, p - and d -wave pairing in neutral as well as in charged Fermi-systems, models of superfluid Bose-systems and Fermi-Bose-mixtures. Within these models they study the collective properties of such systems as superfluid 3 He, superfluid 4 He, superfluid 3 He-
Recent experiments in novel nuclear excitations at the BNL AGS
International Nuclear Information System (INIS)
Chrien, R.E.
1988-01-01
Recent experimental work at the AGS dealing with unusual nuclear excitations is summarized. Three examples are given: the deexcitation of Λ hypernuclei by γ transitions, the production of Λ hypernuclei by the (π + ,K + ) reaction, and the search for /eta/-nuclear excitations. The status of each field and the implications of the research for nuclear theory are discussed. 11 refs., 10 figs., 1 tab
Energy Technology Data Exchange (ETDEWEB)
Khan, E
2005-12-15
The author presents successively the theoretical aspect, the experimental aspect and the applied aspect of excitations in nuclear structures. The quasi-particle random phase approximation (QRPA) tool is first described. Recent approaches on QRPA are based on the theory of the density function where the ground state and excited states are described from the same nucleon-nucleon interaction. 2 methods for measuring the collective excitations are then presented: the proton scattering that has the potentiality to investigate the evolution of magicity, the second method is in fact a new method for measuring the giant mono-polar resonance (GMP) in exotic nuclei. Nuclear reactions are considered as a compulsory step on the way from observables like cross-sections to nuclear structure. The author highlights the assets of the convolution model that can generate the optical potential from the effective nucleon-nucleon interaction and from proton and neutron densities of the nuclei involved. R-processes in nucleosynthesis and neutron stars are reviewed as applications of collective excitations in the field of nuclear astrophysics. (A.C.)
Sum rules for nuclear collective excitations
International Nuclear Information System (INIS)
Bohigas, O.
1978-07-01
Characterizations of the response function and of integral properties of the strength function via a moment expansion are discussed. Sum rule expressions for the moments in the RPA are derived. The validity of these sum rules for both density independent and density dependent interactions is proved. For forces of the Skyrme type, analytic expressions for the plus one and plus three energy weighted sum rules are given for isoscalar monopole and quadrupole operators. From these, a close relationship between the monopole and quadrupole energies is shown and their dependence on incompressibility and effective mass is studied. The inverse energy weighted sum rule is computed numerically for the monopole operator, and an upper bound for the width of the monopole resonance is given. Finally the reliability of moments given by the RPA with effective interactions is discussed using simple soluble models for the hamiltonian, and also by comparison with experimental data
Hyperon excitation in nuclear coulomb field
International Nuclear Information System (INIS)
Vanyashin, A.V.; Nikitin, Yu.P.; Shan'gin, A.A.
1981-01-01
A possibility is studied to measure radiative decay partial widths from the 3/2 + decuplet hyperon resonances by means of the Coulomb excitation method of the octet hyperons. The expected contributions from the strong and electromagnetic interactions in the coherence range to the hyperon excitation cross sections on heavy nuclei and on the 4 He nucleus are estimated. The particle angular distributions in the reactions Σ-+A→Σ-(1385)+A and Λ+A→Σ 0 (1385)+A are analysed in order to determine the energy range where the background conditions are the most favorable to extract the electromagnetic mechanism of the hyperon excitation [ru
Gross properties of nuclei and nuclear excitations XXI
International Nuclear Information System (INIS)
Feldmeier, H.
1993-01-01
These proceedings contain the articles and contributed papers presented at the named workshop. They are concerned with highly excited nuclear matter and relativistic heavy ion reactions together with some related topics. See hints under the relevant topics. (HSI)
Critical insights into nuclear collectivity from complementary nuclear spectroscopic methods
Garrett, P. E.; Wood, J. L.; Yates, S. W.
2018-06-01
Low-energy collectivity of nuclei has been, and is being, characterized in a critical manner using data from a variety of spectroscopic methods, including Coulomb excitation, β decay, inelastic scattering of charged and uncharged particles, transfer reactions, etc. In addition to level energies and spins, transition multipolarities and intensities, lifetimes, and nuclear moments are available. The totality of information from these probes must be considered in achieving an accurate vision of the excitations in nuclei and determining the applicability of nuclear models. From these data, major changes in our view of low-energy collectivity in nuclei have emerged; most notable is the demise of the long-held view of low-energy quadrupole collectivity near closed shells as due to vibrations about a spherical equilibrium shape. In this contribution, we focus on the basic predictions of the spherical harmonic vibrator limit of the Bohr Hamiltonian. Properties such as B(E2) values, quadrupole moments, E0 strengths, etc are outlined. Using the predicted properties as a guide, evidence is cited for and against the existence of vibrational states, and especially multi-phonon states, in nuclei that are, or historically were considered to be, spherical or have a nearly spherical shape in their ground state. It is found that very few of the nuclei that were identified in the last major survey seeking nearly spherical harmonic vibrators satisfy the more stringent guidelines presented herein. Details of these fundamental shifts in our view of low-energy collectivity in nuclei are presented.
Microstructure ion Nuclear Spectra at High Excitation
International Nuclear Information System (INIS)
Ericson, T.E.O.
1969-01-01
The statistical microstructure of highly excited systems is illustrated by the distribution and fluctuations of levels, widths and cross-sections of nuclei both for the case of sharp resonances and the continuum case. The coexistence of simple modes of excitation with statistical effects in terms of strength functions is illustrated by isobaric analogue states. The analogy is made with similar phenomena for coherent light, is solid-state physics and high-energy physics. (author)
Extended RPA study of nuclear collective phenomena
International Nuclear Information System (INIS)
Drozdz, S.
1987-01-01
A fully microscopic study of nuclear collective phenomena is presented within the framework of an extended RPA which includes 1p-1h and 2p-2h excitations in a consistent way. This theory allows us to obtain a very realistic description of various excitation spectra. As a result, a strong evidence of correlation effects beyond mean-field theory emerges. The effective interaction used is a G-matrix derived from the meson-exchange potential. The extended theory introduces also additional correlations which screen the long-large part of the effective interaction. This effect significantly enhances the stability of the ground state against density fluctuations. In this connection a possible importance of relativistic effects is also discussed. 99 refs., 19 figs., 5 tabs. (author)
Gross properties of nuclei and nuclear excitations
International Nuclear Information System (INIS)
Feldmeier, H.
1992-01-01
Heavy ion reactions are the main topics of the workshop. The different aspects that are discussed are: nuclear matter at relativistic energies, the transformation to quark matter, particle production, spallation and theoretical models for nuclear reaction kinetics. (BBOE)
Gross properties of nuclei and nuclear excitations
International Nuclear Information System (INIS)
Feldmeier, H.
1989-01-01
These proceedings contain the articles presented at the named workshop. These concern new developments in nuclear structure studies, relativistic heavy ion reactions, and advanced techniques for nuclear spectroscopy. (HSI)
Energy Technology Data Exchange (ETDEWEB)
Bouneau, Sandra [Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)
1997-04-11
This work aims at the study of different excitation modes, individual and collective, in superdeformed (SD) nuclei in the mass 190 region. The study of {sup 193}Tl and {sup 195,196,197}Bi SD nuclei brought information concerning individual excitation around the proton and neutron SD gaps Z = 80 - 82 and N = 112. Also, the study of the nucleus {sup 196}Pb revealed excited SD states built on collective vibrations. Concerning the isotope {sup 193}Tl, magnetic property analysis has been performed and allowed us to identify the proton intruder orbital {pi}i{sub 13/2} on which the two known SD the bands of the nucleus are build. It was possible to separate experimentally the relative contribution of proton and neutron pairing to the dynamic moment of inertia. Several {gamma} transition of high energy (about 3 MeV) linking SD states to normal deformed states (ND) and three new SD bands have been found in this nucleus. These SD bands have been interpreted in terms of individual excitations of the single proton on different orbitals identified above the proton SD gap Z = 80. An interaction between the states of two excited SD band have been observed and its strength measured. All these results (gyromagnetic factor, the role of nuclear pairing, excitation energy of the SD well, the interaction between two orbitals) represent information of theoretical interest. In each isotope {sup 195-197}Bi, one SD band has been discovered. They have been also interpreted in terms of individual excitation implying the same proton state. The study of this nuclei brought the first experimental proof that the superdeformation phenomenon persists above the shell closure Z = 82. In {sup 196}Pb nucleus a new excited SD band has been discovered. Observations are mentioned suggesting that we have to consider excitations different from those based on individual ones. An interpretation based on vibrational modes can explain both the low energy measured of the excited states in respect with the SD
Gross properties of nuclei and nuclear excitations
International Nuclear Information System (INIS)
Feldmeier, H.
1991-01-01
These proceedings contain the articles presented at the named workshop. They deal with nuclear multifragmentation, heavy ion reaction kinetics, breakup and transfer processes in heavy ion reactions, the production of hypernuclei, nuclear structure in the framework of the quark model and QCD, and particle production in nuclear reactions. (HSI)
Description of nuclear collective motion by Wigner function moments
International Nuclear Information System (INIS)
Balbutsev, E.B.
1996-01-01
The method is presented in which the collective motion is described by the dynamic equations for the nuclear integral characteristics. The 'macroscopic' dynamics is formulated starting from the equations of the microscopic theory. This is done by taking the phase space moments of the Wigner function equation. The theory is applied to the description of collective excitations with multipolarities up to λ=5. (author)
Collective Excitations in Liquid Hydrogen Observed by Coherent Neutron Scattering
DEFF Research Database (Denmark)
da Costa Carneiro, Kim; Nielsen, M.; McTague, J. P.
1973-01-01
Coherent scattering of neutrons by liquid parahydrogen shows the existence of well-defined collective excitations in this liquid. Qualitative similarity with the scattering from liquid helium is found. Furthermore, in the range of observed wave vectors, 0.7 Å-1 ≤κ≤3.1 Å-1, extending from the firs...
On some aspects of Coulomb excitation of nuclear rotational states
International Nuclear Information System (INIS)
Massmann, H.; Robotham, H.
1979-01-01
The Coulomb excitation of nuclear rotational states is studied with a semiclassical method using classical trajectories and the classical action in order to construct the excitation probabilities. This method allows one to consider the effect on the excitation probabilities of a weak nuclear potential. An explicit expression for the 'safe bombarding energy' that is the largest bombarding energy for which the nuclear force can be neglected, is found. Also the transfer of angular momentum to the projectile's orbit is considered. One finds that the dynamical distortion of the orbit has a measurable effect on the excitation probabilities for the case of very heavy ions. Furthermore, new dimensionless parameters measuring the dynamical distortion and the effect of the adiabaticity of the collision are introduced and discussed. (author)
Gross properties of nuclei and nuclear excitations
International Nuclear Information System (INIS)
Feldmeier, H.
1990-01-01
The workshop contains discussions about theory and experiments with heavy ions at intermediate and relativistic energies, spallation, quark matter production and other nuclear matter properties. (BBOE)
Pion absorption in excited nuclear matter
International Nuclear Information System (INIS)
Schmidt, H.R.; Albrecht, R.; Bock, R.; Gutbrod, H.H.; Kolb, B.W.; Lund, I.; Awes, T.C.; Baktash, C.; Ferguson, R.L.; Lee, I.Y.; Plasil, F.; Saini, S.; Tincknell, M.; Young, G.R.; Beckmann, P.; Berger, F.; Clewing, G.; Dragon, L.; Glasow, R.; Kampert, K.H.; Peitzmann, T.; Purschke, M.; Santo, R.; Claesson, G.; Eklund, A.; Garpman, S.; Gustafsson, H.A.; Idh, J.; Oskarsson, A.; Otterlund, I.; Persson, S.; Stenlund, E.; Franz, A.; Jacobs, P.; Poskanzer, A.M.; Ritter, H.G.; Kristiansson, P.; Loehner, H.; Obenshain, F.E.; Sorensen, S.P.; Siemiarczuk, T.
1992-02-01
The target dependence and azimuthal correlations of protons and plons are investigated for pA reactions at 4.9, 60 and 200 GeV. The experimental observations can be understood qualitatively under the assumption that pions are absorbed in excited target spectator matter. (orig.)
Single-particle and collective excitations in Ni-63
Albers, M.; Zhu, S.; Janssens, R. V. F.; Gellanki, Jnaneswari; Ragnarsson, Ingemar; Alcorta, M.; Baugher, T.; Bertone, P. F.; Carpenter, M. P.; Chiara, C. J.; Chowdhury, P.; Deacon, A. N.; Gade, A.; DiGiovine, B.; Hoffman, C. R.
2013-01-01
A study of excited states in Ni-63 up to an excitation energy of 28 MeV and a probable spin of 57/2 was carried out with the Mg-26(Ca-48,2 alpha 3n gamma)Ni-63 reaction at beam energies between 275 and 320 MeV. Three collective bands, built upon states of single-particle character, were identified. For two of the three bands, the transition quadrupole moments were extracted, herewith quantifying the deformation at high spin. The results have been compared with shell-model and cranked Nilsson-...
Gross properties of nuclei and nuclear excitations
International Nuclear Information System (INIS)
Feldmeier, H.
1986-01-01
These proceedings contain the invited and contributed papers presented at the named workshop. They deal with special topics in high- and intermediate-energy nuclear physics. Especially considered are the quark-gluon plasma, ultrarelativistic heavy ion reactions, and the application of QCD to nuclear structure calculations. (HSI)
Gross properties of nuclei and nuclear excitations
International Nuclear Information System (INIS)
Feldmeier, H.
1988-01-01
These proceedings contain the articles presented at the named workshop. They are concerned with the application of the results from high-energy physics to nuclear structure calculations, thermodynamics of nuclear matter, and kinetics of heavy ion reactions with special regard to relativistic processes. (HSI)
Collective excitability in a mesoscopic neuronal model of epileptic activity
Jedynak, Maciej; Pons, Antonio J.; Garcia-Ojalvo, Jordi
2018-01-01
At the mesoscopic scale, the brain can be understood as a collection of interacting neuronal oscillators, but the extent to which its sustained activity is due to coupling among brain areas is still unclear. Here we address this issue in a simplified situation by examining the effect of coupling between two cortical columns described via Jansen-Rit neural mass models. Our results show that coupling between the two neuronal populations gives rise to stochastic initiations of sustained collective activity, which can be interpreted as epileptic events. For large enough coupling strengths, termination of these events results mainly from the emergence of synchronization between the columns, and thus it is controlled by coupling instead of noise. Stochastic triggering and noise-independent durations are characteristic of excitable dynamics, and thus we interpret our results in terms of collective excitability.
Fermionic Collective Excitations in a Lattice Gas of Rydberg Atoms
International Nuclear Information System (INIS)
Olmos, B.; Gonzalez-Ferez, R.; Lesanovsky, I.
2009-01-01
We investigate the many-body quantum states of a laser-driven gas of Rydberg atoms confined to a large spacing ring lattice. If the laser driving is much stronger than the van der Waals interaction among the Rydberg atoms, these many-body states are collective fermionic excitations. The first excited state is a spin wave that extends over the entire lattice. We demonstrate that our system permits us to study fermions in the presence of disorder although no external atomic motion takes place. We analyze how this disorder influences the excitation properties of the fermionic states. Our work shows a route towards the creation of complex many-particle states with atoms in lattices.
Statistical density of nuclear excited states
Directory of Open Access Journals (Sweden)
V. M. Kolomietz
2015-10-01
Full Text Available A semi-classical approximation is applied to the calculations of single-particle and statistical level densities in excited nuclei. Landau's conception of quasi-particles with the nucleon effective mass m* < m is used. The approach provides the correct description of the continuum contribution to the level density for realistic finite-depth potentials. It is shown that the continuum states does not affect significantly the thermodynamic calculations for sufficiently small temperatures T ≤ 1 MeV but reduce strongly the results for the excitation energy at high temperatures. By use of standard Woods - Saxon potential and nucleon effective mass m* = 0.7m the A-dependency of the statistical level density parameter K was evaluated in a good qualitative agreement with experimental data.
Measurement of nuclear potentials from fusion excitation functions
International Nuclear Information System (INIS)
Huizenga, J.R.; Birkelund, J.R.
1984-01-01
The basis for measuring nuclear potentials from fusion excitation functions at energies above barrier is reviewed. It is argued that because of experimental and conceptual problems fusion excitation functions at high energies cannot lead to model independent measurements of internuclear potential at small separations. The Al 27 + Ne 20 reaction previously analyzed by others is used as an example of problems arising from the inability to distinguish complete and incomplete fusion in experimental data
Schematic model of nuclear spin excitations
International Nuclear Information System (INIS)
Boucher, P.M.
1990-01-01
A simple model to estimate the strength of spin and nonspin collective states is presented. The model was inspired by early schematic models based on energy-weighted sum rules and is a useful tool for interpreting experimental data without the complexities of realistic microscopic calculations. The strength of collective states is calculated by assuming that a single collective state completely exhausts the energy-weighted sum rule. 19 refs
Nuclear structure at high excitation energies
Indian Academy of Sciences (India)
Average nuclear shape; giant dipole resonance; static path approximation; linear re- ... On the other hand if the nucleus is already spherical in the ground state ... this approach to study the structural properties as well as level densities of some ... (1) is modeled by a harmonic vibration along the three principal axes and then.
Nuclear excitations and reaction mechanisms: Progress report
International Nuclear Information System (INIS)
Fallieros, S.; Levin, F.S.
1988-01-01
This report describes activities of the Nuclear Theory Group at Brown University during the period 1 August 1987-31 July 1988, under Grant FG02-87ER40334. Completed and on-going research includes various theoretical and numerical studies on: parity non-conserving interactions in a relativistic system, processes involving virtual photons and real photons, deuteron-nucleus and neutron-deuteron collisions systems, and muon-catalyzed fusion
Sensitivity of nonlinear photoionization to resonance substructure in collective excitation
Mazza, T.; Karamatskou, A.; Ilchen, M.; Bakhtiarzadeh, S.; Rafipoor, A. J.; O'Keeffe, P.; Kelly, T. J.; Walsh, N.; Costello, J. T.; Meyer, M.; Santra, R.
2015-01-01
Collective behaviour is a characteristic feature in many-body systems, important for developments in fields such as magnetism, superconductivity, photonics and electronics. Recently, there has been increasing interest in the optically nonlinear response of collective excitations. Here we demonstrate how the nonlinear interaction of a many-body system with intense XUV radiation can be used as an effective probe for characterizing otherwise unresolved features of its collective response. Resonant photoionization of atomic xenon was chosen as a case study. The excellent agreement between experiment and theory strongly supports the prediction that two distinct poles underlie the giant dipole resonance. Our results pave the way towards a deeper understanding of collective behaviour in atoms, molecules and solid-state systems using nonlinear spectroscopic techniques enabled by modern short-wavelength light sources. PMID:25854939
Collective spin wave and phonon excitations in ferromagnetic organic polymers
International Nuclear Information System (INIS)
Leong, Jit-Liang; Sun, Shih-Jye
2013-01-01
We proposed a model to investigate the properties of a conductive and ferromagnetic organic-polymer (OCP), which contains two collective excitations—spin wave and phonon—competing with each other; namely, the spin wave excitation accompanies the electron–phonon (e–ph) interactions in the conductive and ferromagnetic OCP. The ferromagnetism of the OCP is induced from the conductive carriers which couple with the phonon to become polarons. Due to the competition between both excitations, the Curie temperature (T C ) is sensitively suppressed by the e–ph interaction. In addition, an optimal T C with a small e–ph interaction exists in a specific density of conduction carrier, yet is contrary to the large e–ph interaction case. Furthermore, the dimerization, i.e. the atomic displacement induced from the e–ph interactions, increases with the strength of the e–ph interaction and decreases upon reaching the maximum dimerization. (paper)
Semiclassical treatment of nuclear effects in Coulomb excitation
Energy Technology Data Exchange (ETDEWEB)
Canto, L F; Donangelo, R [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Rasmussen, J O; Ring, P; Stoyer, M A [Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.
1990-09-27
We introduce the effects of the nuclear potential in the semiclassical Alder-Winther-de Boer method, both in the coupling matrix elements and as corrections to the Rutherford orbit. We compare our results to those of pure Coulomb excitation and to coupled-channel calculations. (orig.).
Nuclear excitations and reaction mechanisms. Progress report
International Nuclear Information System (INIS)
Fallieros, S.; Levin, F.S.
1986-01-01
Theoretical research is being conducted on the following topics: photon scattering, gauge invariance and the extension of Siefert's Theorem; retardation effects in photonuclear absorption and the Cabibbo Radicati Sum Rule; isovector transition densities, currents and response functions; the electric polarizability, the magnetic susceptibility and the distribution of oscillator strengths in some elementary systems; relativistic models and processes; properties of skyrmions; multiquark compound bags and the charge form factor of the A = 3 nuclei; nuclear reaction theory; three-particle scattering theory; deuteron-nucleus model calculations; asymptotia in three-particle scattering systems; and time-dependent approach to few-nucleon collisions. Progress in each of these areas is reviewed briefly. A list of invited talks and of publications for the fiscal year 1986 is included. 27 refs
Search for dibaryonic de-excitations in relativistic nuclear reactions
International Nuclear Information System (INIS)
Besliu, C.; Popa, V.; Popa, L.; Topor Pop, V.
1993-08-01
Some odd characteristics are observed in the single particle distributions obtained from He + Li interactions at 4.5AGeV/c momenta which are explained as the manifestation of a new mechanism of strangeness production via dibaryonic de-excitations. A signature of the formation of hadronic and baryonic clusters is also reported. The di- pionic signals of the dibaryonic orbital de- excitations are analyzed in the frame of the MIT -bag Model and a Monte Carlo simulation. The role played by the dibaryonic resonances in relativistic nuclear collisions could be a significant one. (author). 29 refs, 7 figs
Search for dibaryonic de-excitations in relativistic nuclear reactions
International Nuclear Information System (INIS)
Besliu, C.; Popa, V.; Popa, L.; Topor Pop, V.
1992-08-01
Some old characteristics are observed in the single particle distributions obtained from He + Li interactions at 4.5 A GeV/c momenta, which are explained as the manifestation of a few mechanism of strangeness production via dibaryonic de-excitations. A signature of formation of hadronic and baryonic clusters is also reported. The di-pionic signals of the dibaryonic orbital de-excitations are analysed in the frame of the MIT-bag model and the Monte Carlo simulation. The role played by the dibaryonic resonances in the relativistic nuclear collisions could be a significant one. (author). 23 refs, 5 figs, 1 tab
Search for collective excitations in nanoparticles of biological origin
International Nuclear Information System (INIS)
Papp, T.; Hunyadi, M.; Gacsi, Z.; Toth, J.; Varga, D.
2009-01-01
Complete text of publication follows. Nanoparticles of biological origin are abundant in nature. One might even consider searching for them in extraterrestrial objects as a remnant of life, and a fingerprint of the existence of primitive life forms billions of years ago. It is also intriguing to consider the potentiality that some of the bacteria use very scarcely available elements for the internal (detoxication) and external (dissimilatory reduction) production of nanocrystals, for example like Te(0). Developing a breathing process based on a rare earth element, certainly is a stretch on the evolution idea. Turning the reasoning around, one can speculate that such primitive life forms have evolved in a very different environment, where the base elements of their make up were abundant, which is not the case on Earth. The late Prof. Terry Beveridge of University of Guelph, ON, Canada raised the idea on a speculative level, that such a characteristic biosignature imposed on a trace element like selenium may conceivably be useful in the search for evidence of extinct microbial communities in sedimentary deposits of extraterrestrial origin (i.e., Mars). These are challenging ideas, but there are potentially imminent benefits of using microorganisms to mass produce nanoparticles. Currently there is technical interest in tellurium with the aim of developing solar cells that have high efficiency to convert sunlight into electrical current. We are involved in photovoltaic technology research, and are developing CdTe detectors for X-ray detection. We have recently observed giant resonances in scintillators, and with doping the CdTe could be turned into PET (Positron Emission Tomography) detector material. Therefore we have interest in the electro-optical properties of Te and Se. Our study of collective excitations and giant resonances in X-ray and nuclear radiation detectors has initiated new models and approaches in detector research. It is well established that giant
Quantum self-organization and nuclear collectivities
Otsuka, T.; Tsunoda, Y.; Togashi, T.; Shimizu, N.; Abe, T.
2018-02-01
The quantum self-organization is introduced as one of the major underlying mechanisms of the quantum many-body systems. In the case of atomic nuclei as an example, two types of the motion of nucleons, single-particle states and collective modes, dominate the structure of the nucleus. The outcome of the collective mode is determined basically by the balance between the effect of the mode-driving force (e.g., quadrupole force for the ellipsoidal deformation) and the resistance power against it. The single-particle energies are one of the sources to produce such resistance power: a coherent collective motion is more hindered by larger gaps between relevant single particle states. Thus, the single-particle state and the collective mode are “enemies” each other. However, the nuclear forces are demonstrated to be rich enough so as to enhance relevant collective mode by reducing the resistance power by changing singleparticle energies for each eigenstate through monopole interactions. This will be verified with the concrete example taken from Zr isotopes. Thus, when the quantum self-organization occurs, single-particle energies can be self-organized, being enhanced by (i) two quantum liquids, e.g., protons and neutrons, (ii) two major force components, e.g., quadrupole interaction (to drive collective mode) and monopole interaction (to control resistance). In other words, atomic nuclei are not necessarily like simple rigid vases containing almost free nucleons, in contrast to the naïve Fermi liquid picture. Type II shell evolution is considered to be a simple visible case involving excitations across a (sub)magic gap. The quantum self-organization becomes more important in heavier nuclei where the number of active orbits and the number of active nucleons are larger. The quantum self-organization is a general phenomenon, and is expected to be found in other quantum systems.
No evidence of reduced collectivity in Coulomb-excited Sn isotopes
Kumar, R.; Saxena, M.; Doornenbal, P.; Jhingan, A.; Banerjee, A.; Bhowmik, R. K.; Dutt, S.; Garg, R.; Joshi, C.; Mishra, V.; Napiorkowski, P. J.; Prajapati, S.; Söderström, P.-A.; Kumar, N.; Wollersheim, H.-J.
2017-11-01
In a series of Coulomb excitation experiments the first excited 2+ states in semimagic Sn 112 ,116 ,118 ,120 ,122 ,124 isotopes were excited using a 58Ni beam at safe Coulomb energy. The B (E 2 ; 0+→2+) values were determined with high precision (˜3 %) relative to 58Ni projectile excitation. These results disagree with previously reported B (E 2 ↑) values [A. Jungclaus et al., Phys. Lett. B 695, 110 (2011)., 10.1016/j.physletb.2010.11.012] extracted from Doppler-shift attenuation lifetime measurements, whereas the reported mass dependence of B (E 2 ↑) values is very similar to a recent Coulomb excitation study [J. M. Allmond et al., Phys. Rev. C 92, 041303(R) (2015), 10.1103/PhysRevC.92.041303]. The stable Sn isotopes, key nuclei in nuclear structure, show no evidence of reduced collectivity and we, thus, reconfirm the nonsymmetric behavior of reduced transition probabilities with respect to the midshell A =116 .
Influence of nuclear dissipation on fission dynamics of the excited ...
Indian Academy of Sciences (India)
2016-05-31
May 31, 2016 ... cle emission starts from an initial state corresponding to the ground state of the compound nucleus whose shape is characterized by the collective coordinate r0, the corresponding conjugate initial momentum p0, the intrinsic excitation energy Eint with the corresponding temperature T0 = √. Eint/a(r0) and ...
New trends in nuclear collective dynamics
International Nuclear Information System (INIS)
Abe, Yasuhisa; Horiuchi, Hisashi; Matsuyanagi, Kenichi
1992-01-01
New Trends in Nuclear Collective Dynamics comprises reviews by well-known researchers from international centers of nuclear physics. This overview of recent advances concentrates on - order amd chaos in finite quantum systems - dissipation in heavy-ion collions - collective motion in warm nuclei - time-dependent mean-field theory with collision terms - nuclear fission and multi-dimensional tunneling - large scale collective motion see hints under the relevent topics. (orig.) With 90 figs
Evolution of collectivity in the 78Ni region: Coulomb excitation of 74Ni at intermediate energies.
Directory of Open Access Journals (Sweden)
Marchi T.
2014-03-01
Full Text Available The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic observables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope (64Ni towards the 78Ni nucleus where the large neutron excess coincides with a double shell closure. In this framework, we have recently performed an experiment with the goal to extract the B(E2; 0+ → 2+ value for the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment: preliminary results are discussed.
Nuclear Excitation by a Zeptosecond Multi-MeV Laser Pulse
International Nuclear Information System (INIS)
Weidenmueller, Hans A.
2011-01-01
A zeptosecond multi-MeV laser pulse may either excite a ''plasma'' of strongly interacting nucleons or a collective mode. We derive the conditions on laser energy and photon number such that either of these scenarios is realized. We use the nuclear giant dipole resonance as a representative example, and a random-matrix description of the fine-structure states and perturbation theory as tools.
Thermodynamics of excited nuclei and nuclear level densities
International Nuclear Information System (INIS)
Ramamurthy, V.S.
1977-01-01
A review has been made of the different approaches that are being used for a theoretical calculation of nuclear level densities. It is pointed out that while the numerical calculations based on the partition function approach and shell model single particle level schemes have shed important insight into the influence of nuclear shell effects on level densities and its excitation energy dependence and have brought out the inadequacy of the conventional Bethe Formula, these calculations are yet to reach a level where they can be directly used for quantitative comparisons. Some of the important drawbacks of the numerical calculations are also discussed. In this context, a new semi-empirical level density formula is described which while retaining the simplicity of analytical formulae, takes into account nuclear shell effects in a more realistic manner. (author)
Theory of nuclear excitation by electron capture for heavy ions
Energy Technology Data Exchange (ETDEWEB)
Gagyi-Palffy, A.
2006-07-01
The resonant process of nuclear excitation by electron capture (NEEC) in collisions involving highly-charged ions has been investigated theoretically. NEEC is a rare recombination process in which a free electron is captured into a bound shell of an ion with the simultaneous excitation of the nucleus. Total cross sections for NEEC followed by the radiative decay of the excited nucleus are presented for various collision systems. The possibility to observe the NEEC in scattering experiments with trapped or stored ions was discussed focusing on the cases with the largest calculated resonance strength. As the photons emitted in different channels of the electron recombination process are indistinguishable in the total cross section, the interference between NEEC followed by the radiative decay of the nucleus and radiative recombination was investigated. The angular distribution of the emitted photons in the recombination process provides means to discern the two processes. Angular differential cross sections for the emitted photons in the case of E2 nuclear transitions were presented for several heavy elements. (orig.)
Nuclear fission fragment excitation of electronic transition laser media
International Nuclear Information System (INIS)
Lorents, D.C.; McCusker, M.V.; Rhodes, C.K.
1976-01-01
The properties of high energy electronic transition lasers excited by fission fragments are expanded. Specific characteristics of the media including density, excitation rates, wavelength, kinetics, fissile material, scale size, and medium uniformity are assessed. The use of epithermal neutrons, homogeneously mixed fissile material, and special high cross section nuclear isotopes to optimize coupling of the energy to the medium are shown to be important considerations maximizing the scale size, energy deposition, and medium uniformity. A performance limit point of approximately 1000 J/l in approximately 100 μs pulses is established for a large class of systems operating in the near ultraviolet and visible spectral regions. It is demonstrated that e-beam excitation can be used to simulate nuclear pumping conditions to facilitate the search for candidate media. Experimental data for the kinetics of a XeF* laser operating in Ar/Xe/F 2 /UF 6 mixtures are given. These reactor-pumped systems are suitable for scaling to volumes on the order of (meters) 3
Hong-Ou-Mandel Interference between Two Deterministic Collective Excitations in an Atomic Ensemble
Li, Jun; Zhou, Ming-Ti; Jing, Bo; Wang, Xu-Jie; Yang, Sheng-Jun; Jiang, Xiao; Mølmer, Klaus; Bao, Xiao-Hui; Pan, Jian-Wei
2016-10-01
We demonstrate deterministic generation of two distinct collective excitations in one atomic ensemble, and we realize the Hong-Ou-Mandel interference between them. Using Rydberg blockade we create single collective excitations in two different Zeeman levels, and we use stimulated Raman transitions to perform a beam-splitter operation between the excited atomic modes. By converting the atomic excitations into photons, the two-excitation interference is measured by photon coincidence detection with a visibility of 0.89(6). The Hong-Ou-Mandel interference witnesses an entangled NOON state of the collective atomic excitations, and we demonstrate its two times enhanced sensitivity to a magnetic field compared with a single excitation. Our work implements a minimal instance of boson sampling and paves the way for further multimode and multiexcitation studies with collective excitations of atomic ensembles.
New laser-driven nuclear excitation studies. Concepts and proposals
International Nuclear Information System (INIS)
Drska, L.; Hanus, V.; Sinor, M.
2010-01-01
Complete text of publication follows. There has been a great interest in the processes of nuclear excitation and triggering in high-parameter laser-produced plasmas in recent years. A series of papers devoted to the theory of this event has been published. Several experiments have already been attempted to study the excitation of the lowest nuclear levels of medium / high-Z nuclides (Ta 181, U 235 etc.), all the same unsuccessful or inconclusive. In the first part of this paper, the situation will be overviewed and analysis of the reasons of this unsatisfactory state of affairs will be accomplished. Prospects of the possible solving of the problem by using novel / projected laser facilities (esp. LIL / PETAL, XFEL, ELI-Phase) will be outlined. Potential of the future ELI Beam Facility in the Czech Republic in this area will be stressed. In the second part, some proposals for the excitation and triggering studies using combined high-power and high-intensity LIL / PETAL system (2012) with multi-kilojoule and multi-petawatt parameters will be discussed. Results of preliminary simulations supporting the thinking about potential projects will be shown and conditions essential for meaningful effort in this area will be analyzed. Problems of realistic simulations of such experiments will be addressed. Completely novel chances for the excitation / triggering studies would be started by constructed / projected facilities XFEL (coherent X-rays ∼ 12 keV, 2014) and ELI (multi-petawatt Phase 1, 2015). Application of intense / coherent high-energy X-rays and / or intense electron / ion beams allows new experimental schemes, extends the range of nuclides to be studied and (maybe) will enable to test some new triggering methods. In the last part of the presentation some possibilities in point (esp. for ELI Beamlines), will be drawn up. Acknowledgements. This research has been supported by the Research Program no. 6840770022 of the Ministry of Education, Youth and Sports of the
Structure of high excited nuclear states and elastic scattering
International Nuclear Information System (INIS)
Zhivopistsev, F.A.; Rzhevskij, E.S.
1979-01-01
An approach to a unified description of nuclear reactions and nuclear structure based on the formalism of the quantum Green functions and on the ideas of the theory of finite Fermi systems has been formulated. New structural vertices are introduced, which are responsible for nucleon collectivization in an atomic nucleus and for the excitation of many-phonon, quasideuteron, quasitriton and other configurations. The vertices define both the processes of particle scattering by atomic nuclei (T matrix and optical potentials) and the nuclear structure (secular equations and wave functions). The vertices are determined from the equations with effective many-particle forces Fsub(nm)sup(c). In their turn the Fsub(nm)sup(c) forces are either determined from a comparison of theory and experiment, or calculated from the equations with more fundamental nucleon-nucleon forces in a nucleus. The effective forces Fsub(nm)sup(c) are more universal than the constants of the theory of finite Fermi-systems, which extends the boundaries of applicability of the particle-hole formalism in the description of nuclear processes. In this approach the traditional methods of description of the nuclear structure, based on particular models of hamiltonian and wave functions, acquire a natural interpretation
Quantum dissipation and decoherence of collective excitations in metallic nanoparticles
Energy Technology Data Exchange (ETDEWEB)
Weick, G.
2006-09-22
The treatment of the surface plasmon as a quantum particle provides a model system for the study of decoherence and quantum dissipation in confined nanoscopic systems, where the role of the electronic correlations is preponderant. Throughout this work we treat the metallic nanoparticle in the jellium approximation where the ionic structure is replaced by a continuous and homogeneous positive charge. The external laser field puts the center of mass into a coherent superposition of its ground and first excited state and thus creates a surface plasmon. The coupling between the center of mass and the relative coordinates causes decoherence and dissipation of this collective excitation. We have developed a theoretical formalism well adapted to the study of this dissipation, which is the reduced-density-matrix formalism. There are mainly two parameters which govern the surface plasmon dynamics: the decay rate of the plasmon, and the resonance frequency. For sizes smaller than 1 nm, presents oscillations as a function of the size. By means of a semiclassical formalism using Gutzwiller's trace formula for the density of states, we have shown that those oscillations are due to the correlations of the density of states of the particles and holes in the nanoparticle. If one considers a noble-metal nanoparticle in an inert matrix, we have shown that a naive application of the Kubo formula for the surface plasmon linewidth fails to reproduce the TDLDA numerical results, which are however consistent with experimental results. We have modified the Kubo theory in order to solve this discrepancy. We have shown, by extending our semiclassical theory to the nonlinear case, that the double plasmon is indeed well defined. We have calculated the lifetime of the double plasmon associated to this second-order effect. In addition to the width, we have also addressed the value of the resonance frequency. The classical electromagnetic Mie theory gives for the resonance frequency of the
International Nuclear Information System (INIS)
2001-01-01
Results of the LI Meeting on Nuclear Spectroscopy and Nuclear Structure are presented. Properties of excited states of atomic nuclei and mechanisms of nuclear reactions are considered. Studies on the theory of nucleus and fundamental interactions pertinent to experimental study of nuclei properties and mechanisms of nuclear reactions, technique and methods of experiment, application of nuclear-physical method, are provided [ru
Pairing and deformation effects in nuclear excitation spectra
Energy Technology Data Exchange (ETDEWEB)
Repko, A. [Slovak Academy of Sciences, Institute of Physics, Bratislava (Slovakia); Kvasil, J. [Charles University, Institute of Particle and Nuclear Physics, Prague (Czech Republic); Nesterenko, V.O. [Joint Institute for Nuclear Research, Laboratory of Theoretical Physics, Dubna (Russian Federation); State University ' ' Dubna' ' , Dubna (Russian Federation); Reinhard, P.G. [Universitaet Erlangen, Institut fuer Theoretische Physik II, Erlangen (Germany)
2017-11-15
We investigate effects of pairing and of quadrupole deformation on two sorts of nuclear excitations, γ-vibrational K{sup π} = 2{sup +} states and dipole resonances (isovector dipole, pygmy, compression, toroidal). The analysis is performed within the quasiparticle random phase approximation (QRPA) based on the Skyrme energy functional using the Skyrme parametrization SLy6. Particular attention is paid to i) the role of the particle-particle (pp) channel in the residual interaction of QRPA, ii) comparison of volume pairing (VP) and surface pairing (SP), iii) peculiarities of deformation splitting in the various resonances. We find that the impact of the pp-channel on the considered excitations is negligible. This conclusion applies also to any other excitation except for the K{sup π} = 0{sup +} states. Furthermore, the difference between VP and SP is found small (with exception of peak height in the toroidal mode). In the low-energy isovector dipole (pygmy) and isoscalar toroidal modes, the branch K{sup π} = 1{sup -} is shown to dominate over the K{sup π} = 0{sup -} one in the range of excitation energy E < 8-10 MeV. The effect becomes impressive for the toroidal resonance whose low-energy part is concentrated in a high peak of almost pure K{sup π} = 1{sup -} nature. This peculiarity may be used as a fingerprint of the toroidal mode in future experiments. The interplay between pygmy, toroidal and compression resonances is discussed, the interpretation of the observed isoscalar giant dipole resonance is partly revised. (orig.)
Isospin effects on collective nuclear dynamics
Di Toro, M; Baran, V; Larionov, A B
1999-01-01
We suggest several ways to study properties of the symmetry term in the nuclear equation of state, EOS, from collective modes in beta-unstable nuclei. After a general discussion on compressibility and saturation density in asymmetric nuclear matter we show some predictions on the collective response based on the solution of generalized Landau dispersion relations. Isoscalar-isovector coupling, disappearance of collectivity and possibility of new instabilities in low and high density regions are discussed with accent on their relation to the symmetry term of effective forces. The onset of chemical plus mechanical instabilities in a dilute asymmetric nuclear matter is discussed with reference to new features in fragmentation reactions.
International Nuclear Information System (INIS)
Bernard, Remi
2012-01-01
Fission is a complex process which highlights many nuclear properties. A major challenge in theoretical nuclear physics nowadays is the development of a consistent approach able to describe on the same footing the whole fission process, i.e. properties of the fissioning system, fission dynamics and fission fragment distributions. As a first step, a microscopic time-dependent and quantum mechanical formalism has been developed based on the Gaussian Overlap Approximation of the Generator Coordinate Method with the adiabatic approximation. Pioneering results obtained for the low-energy fission of 238 U encouraged us to perform new studies of fission along these lines with some additional improvements. For instance, at higher energies, a few MeV above the barrier, the adiabatic approximation doesn't seem valid anymore, and intrinsic excitations have to be taken into account. For that purpose, a new theoretical framework called the Schroedinger Collective Intrinsic Model (SCIM) has been developed, which allows in a microscopic way a simultaneous coupling of single particle and collective degrees of freedom. Such an approach is based on a generalized Generator Coordinate Method (GCM), where the general GCM ansatz of the nuclear wave function is extended by a few excited configurations. Indeed, one considers as generating wave functions not only Hartree Fock Bogolyubov ground-state configurations with different values for the collective generator coordinate but also two quasi particle excited states. Such an approach has the advantage of describing in a completely quantum-mechanical fashion and without phenomenological parameters the coupling of quasi-particle degrees of freedom to the collective motion of the nucleons. In this talk, I will focus on the derivation of the newly developed SCIM formalism. I will first discuss the generalized Hill and Wheeler equation and its transformation into a non local Schroedinger equation by inverting the expansion of the overlap
Instability in nuclear dynamics: loss of collectivity and multifragmentation
International Nuclear Information System (INIS)
Colonna, M.; Di Toro, M.; Guarnera, A.; Latora, V.; Smerzi, A.
1995-01-01
Two limiting cases of nuclear dynamics are analysed: the disappearing of giant collective motions in hot nuclei and the nuclear disassembly in violent heavy ion collisions. For collective vibration build on excited states we get a dramatic increase of the widths of hot Giant Dipole Resonances (GDR). As a consequence of the competition with particle evaporation we get a sharp quenching of giant photon emission. Pre-equilibrium effects on the GDR formation are also accounted for. At high temperature and low density the collective motions can become unstable leading to multifragmentation events in heavy ion collisions. We present a general procedure to identify instability regions and to get informations on the instability point. Some hints towards fully dynamical picture of multi-fragmentation processes are finally suggested. (author)
Collective dose commitments from nuclear power programmes
International Nuclear Information System (INIS)
Beninson, D.
1977-01-01
The concepts of collective dose and collective dose commitment are discussed, particularly regarding their use to compare the relative importance of the exposure from several radiation sources and to predict future annual doses from a continuing practice. The collective dose commitment contributions from occupational exposure and population exposure due to the different components of the nuclear power fuel cycle are evaluated. A special discussion is devoted to exposures delivered over a very long time by released radionuclides of long half-lives and to the use of the incomplete collective dose commitment. The maximum future annual ''per caput'' doses from present and projected nuclear power programmes are estimated
Dissipation and nuclear collective motion
International Nuclear Information System (INIS)
Hofmann, Helmut; Jensen, A.S.; Ngo, Christian; Siemens, P.J.; California Univ., Berkeley
1979-01-01
This contribution is intended to give a brief summary of a forthcoming paper which shall review extensively the linear response theory for dissipation and statistical fluctuations as well as its application to heavy-ion collisions. It shall contain new results on the following subjects: numerical computations of response functions and transport coefficients; dissipation in a self-consistent treatment of harmonic vibrations; introduction of collective variables within a quantum theory. The method used consists of an extended version of the Bohm and Pines treatment of the electron gas. It allows to deduce a quantum Hamiltonian for the collective and intrinsic motion including coupling terms; discussion and solution of a quantal Master equation for non-linear collective motion. Additionally, a somewhat elaborate discussion of the problems of irreversibility is given, especially in connection to a treatment within the moving basis
Collective 0+, 1+ and 2+ excitations in rotating nuclei
International Nuclear Information System (INIS)
Balbutsev, E.B.; Piperova, J.
1988-01-01
The energies and B(Eγ) factors of the isoscalar and isovector 0 + and 2 + resonances are calculated with Skyrme interaction. A satisfactory agreement with experimental data is obtained. It is shown that in rotating nuclei the 2 + excitations split into five branches and also 5 low-lying excitations appear. Two of these low-lying modes are angular resonances and the theory reproduces their energies and B(M1) factors. The experimentally observed splitting of giant monopole resonance in deformed nuclei is confirmed. 34 refs.; 10 figs.; 1 tab
A Neutron Scattering Study of Collective Excitations in Superfluid Helium
DEFF Research Database (Denmark)
Graf, E. H.; Minkiewicz, V. J.; Bjerrum Møller, Hans
1974-01-01
Extensive inelastic-neutron-scattering experiments have been performed on superfluid helium over a wide range of energy and momentum transfers. A high-resolution study has been made of the pressure dependence of the single-excitation scattering at the first maximum of the dispersion curve over...... of the multiexcitation scattering was also studied. It is shown that the multiphonon spectrum of a simple Debye solid with the phonon dispersion and single-excitation cross section of superfluid helium qualitatively reproduces these data....
Energy Technology Data Exchange (ETDEWEB)
Saudinos, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1962-07-01
Inelastic scattering of medium energy a particles by nuclei is known to excite preferentially levels of collective character. We have studied the scattering of isotopically enriched targets of Ca, Fe, Ni, Cu, Zn. In part I, we discuss the theoretical features of the interaction. In part II, we describe the experimental procedure. Results are presented and analysed in part III. {alpha} particles scattering by Ca{sup 40} is showed to excite preferentially odd parity levels. In odd nuclei we have observed multiplets due to the coupling of the odd nucleon with the even-even core vibrations. For even-even nuclei, a few levels are excited with lower cross-sections between the well-known first 2{sup +} and 3{sup -} states. Some could be members of the two phonon quadrupole excitation and involve a double nuclear excitation process. (author) [French] On sait que la diffusion inelastique des particules alpha de moyenne energie excite preferentiellement des niveaux de caractere collectif. Nous avons etudie la diffusion des particules alpha de 44 MeV du cyclotron de Saclay par des isotopes separes de Ca, Fe, Ni, Cu, Zn. Dans la premiere partie nous exposons les theories de cette interaction. Dans la seconde nous decrivons le systeme experimental. Les resultats sont donnes dans la troisieme partie. Nous montrons que les niveaux excites preferentiellement pour {sup 40}Ca par diffusion ({alpha},{alpha}') sont de parite negative. Dans les noyaux pair-impair nous avons observe des multiplets dus au couplage du nucleon celibataire avec les vibrations du coeur pair-pair. Pour les noyaux pair-pair nous avons pu etudier entre le premier niveau 2{sup +} et le niveau 3{sup -} deja bien connus certains etats plus faiblement excites. Il semble qu'ils sont dus a une excitation quadrupolaire a deux phonons et impliquent un processus de double excitation nucleaire. (auteur)
Nuclear spin-isospin excitations from covariant quasiparticle-vibration coupling
Robin, Caroline; Litvinova, Elena
2016-09-01
Methods based on the relativistic Lagrangian of quantum hadrodynamics and nuclear field theory provide a consistent framework for the description of nuclear excitations, naturally connecting the high- and medium-energy scales of mesons to the low-energy domain of nucleonic collective motion. Applied in the neutral channel, this approach has been quite successful in describing the overall transition strength up to high excitation energies, as well as fine details of the low-lying distribution. Recently, this method has been extended to the description of spin-isospin excitations in open-shell nuclei. In the charge-exchange channel, the coupling between nucleons and collective vibrations generates a time-dependent proton-neutron effective interaction, in addition to the static pion and rho-meson exchange, and introduces complex configurations that induce fragmentation and spreading of the resonances. Such effects have a great impact on the quenching of the strength and on the computing of weak reaction rates that are needed for astrophysics modeling. Gamow-Teller transitions in medium-mass nuclei and associated beta-decay half-lives will be presented. Further developments aiming to include additional ground-state correlations will also be discussed. This work is supported by US-NSF Grants PHY-1404343 and PHY-1204486.
Nuclear charge-exchange excitations in a self-consistent covariant approach
International Nuclear Information System (INIS)
Liang, Haozhao
2010-01-01
Nowadays, charge-exchange excitations in nuclei become one of the central topics in nuclear physics and astrophysics. Basically, a systematic pattern of the energy and collectivity of these excitations could provide direct information on the spin and isospin properties of the in-medium nuclear interaction, and the equation of state of asymmetric nuclear matter. Furthermore, a basic and critical quantity in nuclear structure, neutron skin thickness, can be determined indirectly by the sum rule of spin-dipole resonances (SDR) or the excitation energy spacing between the isobaric analog states (IAS) and Gamow-Teller resonances (GTR). More generally, charge-exchange excitations allow one to attack other kinds of problems outside the realm of nuclear structure, like the description of neutron star and supernova evolutions, the β-decay of nuclei which lie on the r-process path of stellar nucleosynthesis, and the neutrino-nucleus cross sections. They also play an essential role in extracting the value of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element V ud via the nuclear 0 + → 0 + superallowed Fermi β decays. For all these reasons, it is important to develop the microscopic theories of charge-exchange excitations and it is the main motivation of the present work. In this work, a fully self-consistent charge-exchange relativistic random phase approximation (RPA) based on the relativistic Hartree-Fock (RHF) approach is established. Its self-consistency is verified by the so-called IAS check. This approach is then applied to investigate the nuclear spin-isospin resonances, isospin symmetry-breaking corrections for the superallowed β decays, and the charged-current neutrino-nucleus cross sections. For two important spin-isospin resonances, GTR and SDR, it is shown that a very satisfactory agreement with the experimental data can be obtained without any readjustment of the energy functional. Furthermore, the isoscalar mesons are found to play an essential role in spin
Excited-state lifetimes of far-infrared collective modes in proteins
Xie, A.; van der Meer, L.; Austin, R. H.
2002-01-01
Vibrational excitations of low frequency collective modes are essential for functionally important conformational transitions in proteins. Here we report the first direct measurement on the lifetime of vibrational excitations of the collective modes at 87 pm (115 cm(-1)) in bacteriorhodopsin, a
A new detection method of 99Tc by nuclear excitation
International Nuclear Information System (INIS)
Sekine, T.; Yoshihara, Kenji; Nemeth, Zs.; Lakosi, L.; Veres, A.
1989-01-01
A new nuclear excitation process, 99 Tc(γ,γ') 99m Tc reaction, was applied for the first time to radioactivation analysis of technetium. Bremsstrahlung irradiation of 99 Tc samples gave the reaction product 99m Tc which emits γ-ray easily measurable by a semiconductor detector. The production rate of 99m Tc per μg 99 Tc was linearly correlated with the flux of bremsstrahlung. The detection limit of 99 Tc was estimated to be nanogram order (0.63 Bq 99 Tc) under the optimum irradiation condition. Possible interference by 100 Ru(γ, p) 99m Tc reaction was also studied, which could be discriminated from the (γ,γ') reaction by simultaneously occurring 98 Ru(γ,p) 97 Ru reaction. (author) 17 refs.; 7 figs
Flow induced vibrational excitation of nuclear reactor structures
International Nuclear Information System (INIS)
Gibert, R.J.
1979-01-01
The pressure fluctuations generated by disturbed flows, encountered in nuclear reactors induce vibrations in the structures. In order to make forecastings for these vibrational levels, it is necessary to know the characteristics of the random pressure fluctuations induced in the walls by the main flow peculiarities of the circuits. This knowledge is essentially provided by experimentation which shows that most of the energy from these fluctuations is in the low frequency area. It is also necessary to determine the transfer functions of the fluid-structure coupled system. Given the frequency range of the excitations, a calculation of the characteristics of the first eigenmodes is generally sufficient. This calculation is carried out by finite element codes, the modal dampings being assessed separately. In this paper, emphasis is placed mainly on the analysis of the sources of excitation due to flow peculiarities. Some examples will also be given of assessments of vibrations in real structures (pipes, reactor internals, etc.) and of comparisons with the experimental results obtained on models or on a site [fr
Fast heavy ion collisions with C60: Collective excitation
International Nuclear Information System (INIS)
Kadhane, Umesh; Kelkar, A.H.; Misra, D.; Kumar, Ajay; Tribedi, L.C.
2006-01-01
Ionization and fragmentation of C 60 in collision with 5 MeV/μm O 6+ ions are studied using recoil ion ToF method. Relative ionization cross sections up to C 60 4+ are determined. The qualitative trend for different C 60 charge states was compared against simple plasmon excitation model
Response function of spin-isospin nuclear excitations
International Nuclear Information System (INIS)
Salvetti, A.R.
1986-01-01
The selected aspects of spin-isospir nuclear excitations are studied. The spreading width of M/ states in even Ca isotopes for the purpose of trying to understand the missing strenght specially in 44 Ca, was estimated. The doorway calculation, was used, considering the level of complexity next to the independent particle M/ state. Using a nuclear matter context, the system response function to a spin-isospin probe and verify how the response function behaves for free fermions and in the ring approximation was studied. Higher correlations to polarization propagation such as the induced interaction and self-energy corrections was introduced. The dopping of colletive effects by such collisions terms was verified. It was investigate how to estimate the short range term of the effective interaction in the spin-isospin channel and the possibility of detecting a difference between these short range terms in the longitudinal and the transverse channel, for understanding the absence of pior condensation precursor states and negative results in a recent attempt to detect differences between longitudinal and transverse response functions one naively expects theoretically. (author) [pt
Microscopic theory of nuclear collective dynamics
International Nuclear Information System (INIS)
Sakata, Fumihiko; Marumori, Toshio; Hashimoto, Yukio; Tsukuma, Hidehiko; Yamamoto, Yoshifumi; Iwasawa, Kazuo.
1990-10-01
A recent development of the INS-TSUKUBA joint research project on large-amplitude collective motion is summarized by putting special emphasis on an inter-relationship between quantum chaos and nuclear spectroscopy. Aiming at introducing various concepts used in this lecture, we start with recapitulating the semi-classical theory of nuclear collective dynamics formulated within the time-dependent Hartree-Fock (TDHF) theory. The central part of the semi-classical theory is provided by the self-consistent collective coordinate (SCC) method which has been developed to properly take account of the non-linear dynamics specific for the finite many-body quantum system. A decisive role of the level crossing dynamics on the order-to-chaos transition of collective motion is discussed in detail. Extending the basic idea of the semi-classical theory, we discuss a full quantum theory of nuclear collective dynamics which allows us to properly define a concept of the quantum integrability as well as the quantum chaoticity for each eigenfunction. The lecture is arranged so as to clearly show the similar structure between the semi-classical and quantum theories of nuclear collective dynamics. Using numerical calculations, we illustrate what the quantum chaos for each eigenfunction means and relate it to the usual definition of quantum chaos for nearest neighbor level spacing statistics based on the random matrix theory. (author)
Collective hypersonic excitations in strongly multiple scattering colloids.
Still, T; Gantzounis, G; Kiefer, D; Hellmann, G; Sainidou, R; Fytas, G; Stefanou, N
2011-04-29
Unprecedented low-dispersion high-frequency acoustic excitations are observed in dense suspensions of elastically hard colloids. The experimental phononic band structure for SiO(2) particles with different sizes and volume fractions is well represented by rigorous full-elastodynamic multiple-scattering calculations. The slow phonons, which do not relate to particle resonances, are localized in the surrounding liquid medium and stem from coherent multiple scattering that becomes strong in the close-packing regime. Such rich phonon-matter interactions in nanostructures, being still unexplored, can open new opportunities in phononics.
Coulomb excitation of $^{116}$Te and $^{118}$Te: a study of collectivity above the Z = 50 shell gap
Cederkall, J A; Smith, J F; Voulot, D; Rahkila, P J; Darby, I G; Hadinia, B; Grahn, T; Paul, E S; Wadsworth, R; Bree, N C F; Baeck, T M; Julin, R J; Diriken, J V J; Jenkins, D G; Kroell, T; Leske, J; Huyse, M L
We propose to study the nature and collectivity of low-energy excitations in $^{116}$Te and $^{118}$Te. We aim to measure the transition probability of the 0$^{+}$ $\\rightarrow$ 2$^{+}$ transition by means of Coulomb excitation, employing REX-ISOLDE and MINIBALL. The proposed study probes the systematics of B(E2) values in light Te nuclei, which lie in a region of the nuclear chart where unusual phenomena and evolution of collectivity have been observed. The proposed study will shed light on the role of the residual proton-neutron interactions in the development of collectivity when approaching the N = Z line. This is a resubmission of the P-277 proposal. The suggestions of INTC have been taken into account and the data from the Yale $^{120}$Te study has been included.
Nuclear Excitation by Electronic Transition of U-235
Energy Technology Data Exchange (ETDEWEB)
Chodash, Perry Adam [Univ. of California, Berkeley, CA (United States)
2015-07-14
Nuclear excitation by electronic transition (NEET) is a rare nuclear excitation that is theorized to occur in numerous isotopes. One isotope in particular, ^{235}U, has been studied several times over the past 40 years and NEET of ^{235}U has never been conclusively observed. These past experiments generated con icting results with some experiments claiming to observe NEET of ^{235}U and others setting limits for the NEET rate. This dissertation discusses the latest attempt to measure NEET of ^{235}U. If NEET of ^{235}U were to occur, ^{235m}U would be created. ^{235m}U decays by internal conversion with a decay energy of 76 eV and a half-life of 26 minutes. A pulsed Nd:YAG laser operating at 1064 nm with a pulse energy of 789 mJ and a pulse width of 9 ns was used to generate a uranium plasma. The plasma was captured on a catcher plate and electrons emitted from the catcher plate were accelerated and focused onto a microchannel plate detector. A decay of 26 minutes would suggest the creation of ^{235m}U and the possibility that NEET occurred. However, measurements performed using a variety of uranium targets spanning depleted uranium up to 99.4% enriched uranium did not observe a 26 minute decay. Numerous other decays were observed with half-lives ranging from minutes up to hundreds of minutes. While NEET of ^{235}U was not observed during this experiment, an upper limit for the NEET rate of ^{235}U was determined. In addition, explanations for the con icting results from previous experiments are given. Based on the results of this experiment and the previous experiments looking for NEET of ^{235}U, it is likely that NEET of ^{235}U has never been observed.
Collective and single-particle states at high excitation energy
International Nuclear Information System (INIS)
Van den Berg, A.M.; Van der Molen, H.K.T.; Harakeh, M.N.; Akimune, H.; Daito, I.; Fujimura, H.; Fujiwara, M.; Ihara, F.; Inomata, T.
2000-01-01
Complete text of publication follows. Damping of high-lying single-particle states was investigated by the study of proton decay from high-lying states in 91 Nb, populated by the 90 Zr(α,t) reaction with E α = 180 MeV. In addition to decay to the ground state of 90 Zr, semi-direct decay was observed to the low-lying (2 + and 3 - ) phonon states, confirming the conclusion from other experiments that these phonon states play an important role in the damping process of the single-particle states. Furthermore, the population and decay of Isobaric Analogue States of 91 Zr, which are located at an excitation energy of about 10 - 12 MeV in 91 Nb, has been studied in the same reaction. (author)
Collectivity and chaoticity in nuclear dynamics
International Nuclear Information System (INIS)
Zelevinsky, V.G.
1992-01-01
Collective and chaotic features of nuclear dynamics are discussed using simple criteria of complexity of wave functions and their coherence with respect to specific operators. Various physical phenomena are considered in this connection: - coherent interaction of collective modes; - fragmentation and spreading widths; - mixing of compound states and dynamical enhancement; - mean field as a smooth component of complicated dynamics; - coupling through continuum and collectivization of widths; - structure of giant resonances; - statistical properties of unstable states as generalization of canonical random matrix ensembles. (orig.)
Parity dependence of the nuclear level density at high excitation
International Nuclear Information System (INIS)
Rao, B.V.; Agrawal, H.M.
1995-01-01
The basic underlying assumption ρ(l+1, J)=ρ(l, J) in the level density function ρ(U, J, π) has been checked on the basis of high quality data available on individual resonance parameters (E 0 , Γ n , J π ) for s- and p-wave neutrons in contrast to the earlier analysis where information about p-wave resonance parameters was meagre. The missing level estimator based on the partial integration over a Porter-Thomas distribution of neutron reduced widths and the Dyson-Mehta Δ 3 statistic for the level spacing have been used to ascertain that the s- and p-wave resonance level spacings D(0) and D(1) are not in error because of spurious and missing levels. The present work does not validate the tacit assumption ρ(l+1, J)=ρ(l, J) and confirms that the level density depends upon parity at high excitation. The possible implications of the parity dependence of the level density on the results of statistical model calculations of nuclear reaction cross sections as well as on pre-compound emission have been emphasized. (orig.)
Nuclear data collection on virtual instrument
International Nuclear Information System (INIS)
Yang Qiang; Lai Wanchang; Hua Yongtai
2007-01-01
This paper introduced a kind of nuclear data collection system using a technique of mixed programming. The system uses parallel port to transport data, MATLAB signal processing software is used for data analysis. It has significantly reduced the difficult of spectral analysis software by using the technique. It has realized signal acquisition in real time and data analysis. (authors)
Collective excitations in liquid and glassy 3-methylpentane
Benassi, Paola
2015-09-28
We present a detailed investigation of the terahertz vibrational dynamics of 3-methylpentane performed by means of high-resolution inelastic x-ray scattering (IXS). We probe the dynamics in a large temperature range, which includes the glass, the supercooled liquid, and the liquid phases. The characteristic frequency of the excitations follows a well-defined dispersion curve extending beyond 8nm−1 at all the investigated temperatures, indicating the persistence of a solidlike behavior also in the liquid phase. This implies the existence of a pseudo-Brillouin zone whose size compares surprisingly well with the periodicity inferred from the first sharp diffraction peak in the static structure factor. We show that, in the investigated temperature range, both sizes undergo a variation of about 15%–20%, comparable to that of the average intermolecular distance. We finally show that the IXS sound velocity coincides with the infinite frequency sound velocity previously inferred from visible and ultraviolet Brillouin spectroscopy data. This analysis confirms the role of the shear relaxation processes in determining the variation with frequency of the apparent sound velocity.
Collective, stochastic and nonequilibrium behavior of highly excited hadronic matter
Energy Technology Data Exchange (ETDEWEB)
Carruthers, P [Los Alamos National Lab., NM (USA). Theoretical Div.
1984-04-23
We discuss selected problems concerning the dynamics and stochastic behavior of highly excited matter, particularly the QCD plasma. For the latter we consider the equation of state, kinetics, quasiparticles, flow properties and possible chaos and turbulence. The promise of phase space distribution functions for covariant transport and kinetic theory is stressed. The possibility and implications of a stochastic bag are spelled out. A simplified space-time model of hadronic collisions is pursued, with applications to A-A collisions and other matters. The domain wall between hadronic and plasma phase is of potential importance: its thickness and relation to surface tension is noticed. Finally, we review the recently developed stochastic cell model of multiparticle distributions and KNO scaling. This topic leads to the notion that fractional dimensions are involved in a rather general dynamical context. We speculate that various scaling phenomena are independent of the full dynamical structure, depending only on a general stochastic framework having to do with simple maps and strange attractors. 42 refs.
Collective, stochastic and nonequilibrium behavior of highly excited hadronic matter
International Nuclear Information System (INIS)
Carruthers, P.
1983-01-01
We discuss selected problems concerning the dynamic and stochasticc behavior of highly excited matter, particularly the QCD plasma. For the latter we consider the equation of state, kinetics, quasiparticles, flow properties and possible chaos and turbulence. The promise of phase space distribution functions for covariant transport and kinetic theory is stressed. The possibility and implications of a stochastic bag are spelled out. A simplified space-time model of hadronic collisions is pursued, with applications to A-A collisions and other matters. The domain wall between hadronic and plasma phase is of potential importance: its thickness and relation to surface tension are noticed. Finally we reviewed the recently developed stochastic cell model of multiparticle distributions and KNO scaling. This topic leads to the notion that fractal dimensions are involved in a rather general dynamical context. We speculate that various scaling phenomena are independent of the full dynamical structure, depending only on a general stochastic framework having to do with simple maps and strange attractors. 42 references
Collective excitations in liquid and glassy 3-methylpentane
Benassi, Paola; Nardone, Michele; Giugni, Andrea; Baldi, Giacomo; Fontana, Aldo
2015-01-01
We present a detailed investigation of the terahertz vibrational dynamics of 3-methylpentane performed by means of high-resolution inelastic x-ray scattering (IXS). We probe the dynamics in a large temperature range, which includes the glass, the supercooled liquid, and the liquid phases. The characteristic frequency of the excitations follows a well-defined dispersion curve extending beyond 8nm−1 at all the investigated temperatures, indicating the persistence of a solidlike behavior also in the liquid phase. This implies the existence of a pseudo-Brillouin zone whose size compares surprisingly well with the periodicity inferred from the first sharp diffraction peak in the static structure factor. We show that, in the investigated temperature range, both sizes undergo a variation of about 15%–20%, comparable to that of the average intermolecular distance. We finally show that the IXS sound velocity coincides with the infinite frequency sound velocity previously inferred from visible and ultraviolet Brillouin spectroscopy data. This analysis confirms the role of the shear relaxation processes in determining the variation with frequency of the apparent sound velocity.
Large amplitude collective nuclear motion and soliton concept
International Nuclear Information System (INIS)
Kartavenko, V.G.; Joint Inst. for Nuclear Research, Dubna
1993-01-01
An application of a soliton theory methods to some nonlinear problems in low and intermediate energies (E ∼ 10--100MeV/nucleon) nucleus - nucleus collisions are presented. Linear and nonlinear excitations of the nuclear density are investigated in the framework of nuclear hydrodynamics. The problem of dynamical instability and clusterization phenomena in a breakup of excited nuclear systems are considered from the points of view of a soliton concept
Collective multipole excitations based on correlated realistic nucleon-nucleon interactions
International Nuclear Information System (INIS)
Paar, N.; Papakonstantinou, P.; Hergert, H.; Roth, R.
2006-01-01
We investigate collective multipole excitations for closed shell nuclei from 16 O to 208 Pb using correlated realistic nucleon-nucleon interactions in the framework of the random phase approximation (RPA). The dominant short-range central and tensor correlations a re treated explicitly within the Unitary Correlation Operator Method (UCOM), which provides a phase-shift equivalent correlated interaction VUCOM adapted to simple uncorrelated Hilbert spaces. The same unitary transformation that defines the correlated interaction is used to derive correlated transition operators. Using VUCOM we solve the Hartree-Fock problem and employ the single-particle states as starting point for the RPA. By construction, the UCOM-RPA is fully self-consistent, i.e. the same correlated nucleon-nucleon interact ion is used in calculations of the HF ground state and in the residual RPA interaction. Consequently, the spurious state associated with the center-of-mass motion is properly removed and the sum-rules are exhausted within ±3%. The UCOM-RPA scheme results in a collective character of giant monopole, dipole, and quadrupole resonances in closed-shell nuclei across the nuclear chart. For the isoscalar giant monopole resonance, the resonance energies are in agreement with experiment hinting at a reasonable compressibility. However, in the 1 - and 2 + channels the resonance energies are overestimated due to missing long-range correlations and three-body contributions. (orig.)
Analysis about modeling MEC7000 excitation system of nuclear power unit
Liu, Guangshi; Sun, Zhiyuan; Dou, Qian; Liu, Mosi; Zhang, Yihui; Wang, Xiaoming
2018-02-01
Aiming at the importance of accurate modeling excitation system in stability calculation of nuclear power plant inland and lack of research in modeling MEC7000 excitation system,this paper summarize a general method to modeling and simulate MEC7000 excitation system. Among this method also solve the key issues of computing method of IO interface parameter and the conversion process of excitation system measured model to BPA simulation model. At last complete the simulation modeling of MEC7000 excitation system first time in domestic. By used No-load small disturbance check, demonstrates that the proposed model and algorithm is corrective and efficient.
A Microscopic Quantal Model for Nuclear Collective Rotation
International Nuclear Information System (INIS)
Gulshani, P.
2007-01-01
A microscopic, quantal model to describe nuclear collective rotation in two dimensions is derived from the many-nucleon Schrodinger equation. The Schrodinger equation is transformed to a body-fixed frame to decompose the Hamiltonian into a sum of intrinsic and rotational components plus a Coriolis-centrifugal coupling term. This Hamiltonian (H) is expressed in terms of space-fixed-frame particle coordinates and momenta by using commutator of H with a rotation angle. A unified-rotational-model type wavefunction is used to obtain an intrinsic Schrodinger equation in terms of angular momentum quantum number and two-body operators. A Hartree-Fock mean-field representation of this equation is then obtained and, by means of a unitary transformation, is reduced to a form resembling that of the conventional semi-classical cranking model when exchange terms and intrinsic spurious collective excitation are ignored
Microscopic boson approach to nuclear collective motion
International Nuclear Information System (INIS)
Kuchta, R.
1989-01-01
A quantum mechanical approach to the maximally decoupled nuclear collective motion is proposed. The essential idea is to transcribe the original shell-model Hamiltonian in terms of boson operators, then to isolate the collective one-boson eigenstates of the mapped Hamiltonian and to perform a canonical transformation which eliminates (up to the two-body terms) the coupling between the collective and noncollective bosons. Unphysical states arising due to the violtion of the Pauli principle in the boson space are identified and removed within a suitable approximation. The method is applied to study the low-lying collective states of nuclei which are successfully described by the exactly solvable multilevel pairing Hamiltonian (Sn, Ni, Pb). 75 refs.; 8 figs
U(6)-phonon model of nuclear collective motion
International Nuclear Information System (INIS)
Ganev, H.G.
2015-01-01
The U(6)-phonon model of nuclear collective motion with the semi-direct product structure [HW(21)]U(6) is obtained as a hydrodynamic (macroscopic) limit of the fully microscopic proton–neutron symplectic model (PNSM) with Sp(12, R) dynamical group. The phonon structure of the [HW(21)]U(6) model enables it to simultaneously include the giant monopole and quadrupole, as well as dipole resonances and their coupling to the low-lying collective states. The U(6) intrinsic structure of the [HW(21)]U(6) model, from the other side, gives a framework for the simultaneous shell-model interpretation of the ground state band and the other excited low-lying collective bands. It follows then that the states of the whole nuclear Hilbert space which can be put into one-to-one correspondence with those of a 21-dimensional oscillator with an intrinsic (base) U(6) structure. The latter can be determined in such a way that it is compatible with the proton–neutron structure of the nucleus. The macroscopic limit of the Sp(12, R) algebra, therefore, provides a rigorous mechanism for implementing the unified model ideas of coupling the valence particles to the core collective degrees of freedom within a fully microscopic framework without introducing redundant variables or violating the Pauli principle. (author)
Role of nuclear couplings in the inelastic excitation of weakly-bound neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Dasso, C.H. [Niels Bohr Institute, Copenhagen (Denmark); Lenzi, S.M.; Vitturi, A. [Universita di Padova (Italy)
1996-12-31
Much effort is presently devoted to the study of nuclear systems far from the stability line. Particular emphasis has been placed in light systems such as {sup 11}Li, {sup 8}B and others, where the very small binding energy of the last particles causes their density distribution to extend considerably outside of the remaining nuclear core. Some of the properties associated with this feature are expected to characterize also heavier systems in the vicinity of the proton or neutron drip lines. It is by now well established that low-lying concentrations of multipole strength arise from pure configurations in which a peculiar matching between the wavelength of the continuum wavefunction of the particles and the range of the weakly-bound hole states occurs. To this end the authors consider the break-up of a weakly-bound system in a heavy-ion collision and focus attention in the inelastic excitation of the low-lying part of the continuum. They make use of the fact that previous investigations have shown that the multipole response in this region is not of a collective nature and describe their excited states as pure particle-hole configurations. Since the relevant parameter determining the strength distributions is the binding energy of the last bound orbital they find it most convenient to use single-particle wavefunctions generated by a sperical square-well potential with characteristic nuclear dimensions and whose depth has been adjusted to give rise to a situation in which the last occupied neutron orbital is loosely-bound. Spin-orbit couplings are, for the present purpose, ignored. The results of this investigation clearly indicate that nuclear couplings have the predominant role in causing projectile dissociation in many circumstances, even at bombarding energies remarkably below the Coulomb barrier.
Study of excitation energy dependence of nuclear level density parameter
International Nuclear Information System (INIS)
Mohanto, G.; Nayak, B.K.; Saxena, A.
2016-01-01
In the present study, we have populated CN by fusion reaction and excitation energy of the intermediate nuclei is determined after first chance α-emission to investigate excitation energy dependence of the NLD parameter. Evaporated neutron spectra were measured following alpha evaporation for obtaining NLD parameter for the reaction 11 B + 197 Au, populating CN 208 Po. This CN after evaporating an α-particle populates intermediate nucleus 204 Pb. The 204 Pb has magic number of Z=82. Our aim is to study the excitation energy dependence of NLD parameter for closed shell nuclei
Influence of collective excitations on pre-equilibrium and equilibrium processes
International Nuclear Information System (INIS)
Ignatyuk, A.V.; Lunev, V.P.
1990-01-01
The influence of the collective states excitations on equilibrium and preequilibrium processes in reaction is discussed. It is shown that for a consistent description of the contribution of preequilibrium and equilibrium compound processes collective states should be taken into account in the level density calculations. The microscopic and phenomenological approaches for the level density calculations are discussed. 13 refs.; 8 figs
Collective Excitations in Protein as a Measure of Balance Between its Softness and Rigidity
International Nuclear Information System (INIS)
Shrestha, Utsab R.; Bhowmik, Debsindhu; Van Delinder, Kurt W.; Mamontov, Eugene; O’Neill, Hugh
2017-01-01
Here, we elucidate the protein activity from the perspective of protein softness and flexibility by studying the collective phonon-like excitations in a globular protein, human serum albumin (HSA), and taking advantage of the state-of-the-art inelastic X-ray scattering (IXS) technique. Such excitations demonstrate that the protein becomes softer upon thermal denaturation due to disruption of weak noncovalent bonds. On the other hand, no significant change in the local excitations is detected in ligand- (drugs) bound HSA compared to the ligand-free HSA. These results clearly suggest that the protein conformational flexibility and rigidity are balanced by the native protein structure for biological activity.
Collective Excitations in Protein as a Measure of Balance Between its Softness and Rigidity
Energy Technology Data Exchange (ETDEWEB)
Shrestha, Utsab R. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy; Bhowmik, Debsindhu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computational Science and Engineering Division; Van Delinder, Kurt W. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy; Mamontov, Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division; O’Neill, Hugh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology and Soft Matter Division; Zhang, Qiu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology and Soft Matter Division; Alatas, Ahmet [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source; Chu, Xiang-Qiang [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy
2017-01-12
Here, we elucidate the protein activity from the perspective of protein softness and flexibility by studying the collective phonon-like excitations in a globular protein, human serum albumin (HSA), and taking advantage of the state-of-the-art inelastic X-ray scattering (IXS) technique. Such excitations demonstrate that the protein becomes softer upon thermal denaturation due to disruption of weak noncovalent bonds. On the other hand, no significant change in the local excitations is detected in ligand- (drugs) bound HSA compared to the ligand-free HSA. These results clearly suggest that the protein conformational flexibility and rigidity are balanced by the native protein structure for biological activity.
Exclusion of nuclear forces in heavy-ion Coulomb excitation and Coulomb fission experiments
International Nuclear Information System (INIS)
Neese, R.E.; Guidry, M.W.
1982-01-01
A simple prescription for estimating the energy at which nuclear forces begin to play a role in heavy-ion Coulomb excitation and Coulomb fission experiments is presented. The method differs from most commonly used recipes in accounting for projectile and target nucleus deformation effects. Using a single adjustable parameter the formula reproduces the energy for the onset of Coulomb-nuclear interference effects for a broad range of heavy-ion systems. It is suggested that most Coulomb fission experiments which have been done involve both Coulomb and nuclear excitation processes and should more properly be termed Coulomb-nuclear fission experiments
Enhanced E3 Excitations in 144,146Ba and the Evolution of Octupole Collectivity
Bucher, B.; Zhu, S.; ANL, LLNL, LBNL, INL, UAM, Rochester, Maryland Collaboration
2017-09-01
Recent Coulomb excitation studies on 144,146Ba using the GRETINA-CHICO2 detection system with post-accelerated CARIBU beams have confirmed the existence of enhanced E3 transitions in these isotopes which are centered in a region that has long been predicted to exhibit stable octupole-deformed shapes. Furthermore, the widely-varying E1 strength observed between these isotopes is well-accounted for by models having octupole-deformed potentials, and the variation has been linked to increased occupancies of specific single-particle orbitals in the reflection-asymmetric potential. This talk will summarize the most recent experimental and theoretical results. In addition, data on octupole-related properties in the surrounding isotopes will be discussed in an attempt to better understand the origin and evolution of octupole collectivity in this mass region. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (ANL), DE-AC02-05CH11231 (LBNL, GRETINA), DOE DE-AC52-07NA27344 (LLNL), DE-AC07-05ID14517 (INL), and MINECO (Spain).
Preparations for an optical access to the lowest nuclear excitation in {sup 229}Th
Energy Technology Data Exchange (ETDEWEB)
Wense, Lars v.d.; Seiferle, Benedict; Thirolf, Peter [Ludwig-Maximilians-Universitaet Muenchen (Germany); Laatiaoui, Mustapha [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH (Germany)
2014-07-01
The isomeric lowest excited nuclear level of {sup 229}Th has been indirectly measured to be 7.6±0.5 eV (163±11 nm). In order to improve the accuracy as prerequisite of an all-optical control, {sup 229m}Th is populated via a 2% decay branch in the α decay of {sup 233}U. The Thorium ions are extracted and cooled with the help of a buffer gas stopping cell and an RFQ-cooler. In order to suppress accompanying α decay chain products other than {sup 229}Th, a quadrupole mass spectrometer (QMS) is used, performance and extraction efficiency measurements were performed. Following the QMS, the Thorium isomers will be collected on a 50 μm micro electrode. The decay of these isomers can then be detected using deep UV optics, presently in the phase of preparation and adjustment. Newest results are presented.
Nuclear-excited Feshbach resonances in the electron scattering from hydrogen halides
International Nuclear Information System (INIS)
Knoth, G.; Gote, M.; Radle, M.; Jung, K.; Ehrhardt, H.
1989-01-01
The energy dependences of the differential cross sections for the electron impact excitation of the higher vibrational levels (v=2 and v=3) of HF and HCl have been measured. Besides the threshold peak a resonance structure has been observed in the v=3 excitation functions of HF below the cusp structure at the opening of the v=4 channel. This resonance structure is the first experimental proof for the existence of the nuclear-excited Feshbach resonances which are interpreted to be the origin of the threshold peaks in the vibrational excitation channels
Collective control of a nuclear reactor
Energy Technology Data Exchange (ETDEWEB)
Rognin, L
1995-06-01
Nowadays, mainly related to the increasing complexity of working environments, working activities become more and collective. The present research on the paradoxical nature of working teams, considered from a reliability point of view. This document is composed of four Sections. The first Section introduces the context of the research, its objectives and the underlying assumptions. In the second Section, we describe a working situation, which is the control of a nuclear reactor. Relations between cooperative work and reliability are discussed in the third Section. Finally, in the fourth Section, a synthesis of the research and some perspectives are proposed. (authors). 7 refs.
Collective control of a nuclear reactor
International Nuclear Information System (INIS)
Rognin, L.
1995-06-01
Nowadays, mainly related to the increasing complexity of working environments, working activities become more and collective. The present research on the paradoxical nature of working teams, considered from a reliability point of view. This document is composed of four Sections. The first Section introduces the context of the research, its objectives and the underlying assumptions. In the second Section, we describe a working situation, which is the control of a nuclear reactor. Relations between cooperative work and reliability are discussed in the third Section. Finally, in the fourth Section, a synthesis of the research and some perspectives are proposed. (authors). 7 refs
Nuclear collective states at finite temperature
International Nuclear Information System (INIS)
Milian, A.; Barranco, M.; Mas, D.; Lombard, R.J.
1987-04-01
The Energy Density Method (EDM) has been used to study low-lying nuclear collective states as well as isoscalar giant resonances at finite temperature (T). Giant states have been studied by computing the corresponding strength function moments (sum rules) in the Random-Phase Approximation (RPA). For the description of the low lying states we have resorted to a variety of models from the rather sophisticated RPA method to liquid drop and schematic models. It has been found that low lying states are most affected by thermal effects, giant resonances being little affected in the range of temperatures here studied
International Nuclear Information System (INIS)
Li, J.; Yu, R.; Yang, X.
2008-01-01
We study the propagation of two quantized optical fields via considering the collective effects of photonic emissions and excitations of a three-level cyclic-type system (such as atomic ensemble with symmetry broken, or the chiral molecular gases, or manual 'atomic' array with symmetry broken), where the quantum transitions is driven by two quantized fields and a classical one. The results show that the parametric conversion and maximally entangled photon pair generation can be achieved by means of the collective excitation of the two upper energy levels induced by the classic optical field. This investigation may be used for the generated coherent short-wavelength quantum radiation and quantum information processing
Collective excitations in the transitional nuclei /sup 224,226,228,230 /Ra
Kurcewicz, W; Kaffrell, N; Nyman, G H; Ruchowska, E
1981-01-01
The gamma -rays following the beta -decay of /sup 224,226,228,230/Fr have been investigated by means of gamma -ray singles (including multispectrum analysis) and gamma gamma coincidence measurements using Ge(Li) spectrometers. The study of the excited levels in /sup 224,226,228,230/Ra is focused on the properties of collective states. The analysis of the results leads one to the conclusion that a ground- state octupole deformation is the most likely explanation for the special features of the collective excitations in Ra and some neighbouring nuclei in the N136 region. (15 refs).
Nuclear Spin Nanomagnet in an Optically Excited Quantum Dot
Korenev, V. L.
2007-12-01
Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins—the nuclear spin nanomagnet.
The Δ excitation in the nuclear-charge longitudinal response
International Nuclear Information System (INIS)
Amore, P.; Cenni, R.; Saracco, P.; Genoa Univ., Genoa
1999-01-01
The presence of a resonant structure corresponding to the Δ excitation in the longitudinal response to an e.m. probe is investigated. It is shown that many-body effects could significantly increase the relativistic contribution suggested by M. Ericson and coworkers
Nuclear Data Covariances in the Indian Context – Progress, Challenges, Excitement and Perspectives
International Nuclear Information System (INIS)
Ganesan, S.
2015-01-01
We present a brief overview of progress, challenges, excitement and perspectives in developing nuclear data covariances in the Indian context in relation to target accuracies and sensitivity studies that are of great importance to Bhabha's 3-stage nuclear programme for energy and non-energy applications
Coulomb and nuclear excitations of narrow resonances in 17Ne
Directory of Open Access Journals (Sweden)
J. Marganiec
2016-08-01
Full Text Available New experimental data for dissociation of relativistic 17Ne projectiles incident on targets of lead, carbon, and polyethylene targets at GSI are presented. Special attention is paid to the excitation and decay of narrow resonant states in 17Ne. Distributions of internal energy in the O15+p+p three-body system have been determined together with angular and partial-energy correlations between the decay products in different energy regions. The analysis was done using existing experimental data on 17Ne and its mirror nucleus 17N. The isobaric multiplet mass equation is used for assignment of observed resonances and their spins and parities. A combination of data from the heavy and light targets yielded cross sections and transition probabilities for the Coulomb excitations of the narrow resonant states. The resulting transition probabilities provide information relevant for a better understanding of the 17Ne structure.
Nuclear spin-orbit splitting from an intermediate Δ excitation
International Nuclear Information System (INIS)
Ohta, K.; Terasawa, T.; Tohyama, M.
1980-01-01
The strength of the single particle spin-orbit potential is calculated from the two pion exchange box diagrams involving an intermediate Δ(1232) resonance excitation by taking account of the exclusion principle for the intermediate nucleon states. The effect of the rho meson is also considered. The predicted strength is found to account for a substantial part of the empirical spin-orbit splittings
Nuclear isovector giant resonances excited by pion single charge exchange
International Nuclear Information System (INIS)
King, B.H.
1993-07-01
This thesis is an experimental study of isovector giant resonances in light nuclei excited by pion single charge exchange reactions. Giant dipole resonances in light nuclei are known to be highly structured. For the mass 9 and 13 giant dipole resonances, isospin considerations were found to be very important to understanding this structure. by comparing the excitation functions from cross section measurements of the (π + , π 0 ) and (π, π 0 ) inclusive reactions, the authors determined the dominant isospin structure of the analog IVGR's. The comparison was made after decomposing the cross section into resonant and non-resonant components. This decomposition is made in the framework of strong absorption and quasi-free scattering. Measurements in the region of the isovector giant dipole resonances (IVGDR) were made to cover the inclusive angular distributions out to the second minimum. Study of the giant resonance decay process provides further understanding of the resonances. This study was carried out by observing the (π + , π 0 p) coincident reactions involving the resonances of 9 B and 13 N excited from 9 Be and 13 C nuclei. These measurements determined the spectra of the decay protons. This method also permitted a decomposition of the giant resonances into their isospin components. The multipolarities of the resonances were revealed by the decay proton angular correlations which, for dipoles, are of the form 1 + A 2 P 2 (cos θ)
Neutrino-pair emission from nuclear de-excitation in core-collapse supernova simulations
Fischer, T.; Langanke, K.; Martínez-Pinedo, G.
2013-12-01
We study the impact of neutrino-pair production from the de-excitation of highly excited heavy nuclei on core-collapse supernova simulations, following the evolution up to several 100 ms after core bounce. Our study is based on the agile-boltztransupernova code, which features general relativistic radiation hydrodynamics and accurate three-flavor Boltzmann neutrino transport in spherical symmetry. In our simulations the nuclear de-excitation process is described in two different ways. At first we follow the approach proposed by Fuller and Meyer [Astrophys. J.AJLEEY0004-637X10.1086/170317 376, 701 (1991)], which is based on strength functions derived in the framework of the nuclear Fermi-gas model of noninteracting nucleons. Second, we parametrize the allowed and forbidden strength distributions in accordance with measurements for selected nuclear ground states. We determine the de-excitation strength by applying the Brink hypothesis and detailed balance. For both approaches, we find that nuclear de-excitation has no effect on the supernova dynamics. However, we find that nuclear de-excitation is the leading source for the production of electron antineutrinos as well as heavy-lepton-flavor (anti)neutrinos during the collapse phase. At sufficiently high densities, the associated neutrino spectra are influenced by interactions with the surrounding matter, making proper simulations of neutrino transport important for the determination of the neutrino-energy loss rate. We find that, even including nuclear de-excitations, the energy loss during the collapse phase is overwhelmingly dominated by electron neutrinos produced by electron capture.
Development of the system for excitation function automatic measurement of nuclear reactions
International Nuclear Information System (INIS)
Sapozhnikov, A.B.
2004-01-01
Full text: The resonance nuclear reaction method is applied at the tandem accelerator UKP-2-1 to determinate films thickness and obtain light element depth distribution. The system for automatic measurement of the nuclear reaction excitation curve has been developed. It allowed to obtain an excitation function of nuclear reaction using continuous changing potential of the target with energy step of 6 eV. Saw-tooth voltage with amplitude up to 6 kV from the block of scanning beam is fed to a target. The amplitude is determined by constant voltage from the scanning beam block control. Nal(Tl) detector detects gamma quanta - the products of a nuclear reaction and transforms they in voltage impulses. The impulses through the amplifier income in the single-channel analyzer which forms impulses to start the analog-to-digital converter. The value of saw-tooth voltage corresponding to the moment of gamma quantum detection is read by the analog-to-digital converter, where it is transformed to digital code and transmitted to the computer. The computer program has been developed to control the process of accumulation of excitation function. The dependence a detected γ-quanta yield from a target potential is automatically plotted by the program. This dependence corresponds to the nuclear reaction excitation function. If scanning amplitude is not enough in order to scan need depth of a sample, an operator increases energy of the proton beam changing high voltage potential of the terminal up 3 keV and measures the nuclear reaction excitation function with the new energy. This procedure can be repeated some times. After that 'sewing' of excitation functions is carried out by the program under the hypothesis that nuclear reaction yield in last points be identical
The collectivity and the de-excitation of the yrast superdeformed band in sup 150 Gd
Energy Technology Data Exchange (ETDEWEB)
Fallon, P.; Alderson, A.; Ali, I.; Cullen, D.M.; Forsyth, P.D.; Riley, M.A.; Roberts, J.W.; Sharpey-Schafer, J.F.; Twin, P.J. (Liverpool Univ. (UK). Oliver Lodge Lab.); Bentley, M.A.; Bruce, A.M. (Science and Engineering Research Council, Daresbury (UK). Daresbury Lab.)
1991-03-28
A Doppler shift attenuation measurement has been carried out to determine the collectivity of the superdeformed band in {sup 150}Gd. The data was found to be consistent with a constant inband quadrupole moment of 17+-3 eb. This corresponds to a quadrupole deformation of {beta}{sub 2}{approx equal}0.58. In addition the measurement has resolved important questions regarding the de-excitation of the band, confirming the rapid de-excitation of the superdeformed band in {sup 150}Gd with more than 80% of the band intensity being lost over one transition. (orig.).
{gamma}-radiation of excited nuclear discrete levels in peripheral heavy ion collisions
Energy Technology Data Exchange (ETDEWEB)
Korotkikh, V.L.; Chikin, K.A. [Scobeltsyn Institute of Nuclear Physics, Moscow State University (Russian Federation)
2002-06-01
A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High-energy photons are emitted by the exited nuclei with energies up to a few tens of GeV at angles of a few hundred microradians with respect to the beam direction. We show that a two-stage process, where an electron-positron pair is produced by virtual photons emitted by nuclei and then the electron or positron excites the nucleus, has a large cross-section. It is equal to about 5 b for CaCa collisions. On the one hand, it produces a significant {gamma}-rays background in the nuclear fragmentation region but, on the other hand, it could be used for monitoring the nuclear beam intensity at the LHC. These secondary nuclear photons could be a good signal for triggering peripheral nuclear collisions. (orig.)
γ-radiation of excited nuclear discrete levels in peripheral heavy ion collisions
Korotkikh, V. L.; Chikin, K. A.
A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High-energy photons are emitted by the exited nuclei with energies up to a few tens of GeV at angles of a few hundred microradians with respect to the beam direction. We show that a two-stage process, where an electron-positron pair is produced by virtual photons emitted by nuclei and then the electron or positron excites the nucleus, has a large cross-section. It is equal to about 5 b for CaCa collisions. On the one hand, it produces a significant γ-rays background in the nuclear fragmentation region but, on the other hand, it could be used for monitoring the nuclear beam intensity at the LHC. These secondary nuclear photons could be a good signal for triggering peripheral nuclear collisions.
γ-radiation of excited nuclear discrete levels in peripheral heavy ion collisions
International Nuclear Information System (INIS)
Korotkikh, V.L.; Chikin, K.A.
2002-01-01
A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High-energy photons are emitted by the exited nuclei with energies up to a few tens of GeV at angles of a few hundred microradians with respect to the beam direction. We show that a two-stage process, where an electron-positron pair is produced by virtual photons emitted by nuclei and then the electron or positron excites the nucleus, has a large cross-section. It is equal to about 5 b for CaCa collisions. On the one hand, it produces a significant γ-rays background in the nuclear fragmentation region but, on the other hand, it could be used for monitoring the nuclear beam intensity at the LHC. These secondary nuclear photons could be a good signal for triggering peripheral nuclear collisions. (orig.)
Nuclear excitation in the reaction 207Pb(μ-,ν6n)201Tl
International Nuclear Information System (INIS)
Budick, B.; Anigstein, R.; Kast, J.W.
1982-01-01
A probability of roughly 1% has been measured for the formation of the first excited state of 201 Tl following muon capture on 207 Pb. A probability of this magnitude for 6 neutron emission may indicate structure in the nuclear excitation function near 54 MeV. An alternative interpretation is provided by muon capture on a correlated np pair in analogy with pion absorption. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Robin, Caroline; Litvinova, Elena [Western Michigan University, Department of Physics, Kalamazoo, MI (United States)
2016-07-15
A new theoretical approach to spin-isospin excitations in open-shell nuclei is presented. The developed method is based on the relativistic meson-exchange nuclear Lagrangian of Quantum Hadrodynamics and extends the response theory for superfluid nuclear systems beyond relativistic quasiparticle random phase approximation in the proton-neutron channel (pn-RQRPA). The coupling between quasiparticle degrees of freedom and collective vibrations (phonons) introduces a time-dependent effective interaction, in addition to the exchange of pion and ρ-meson taken into account without retardation. The time-dependent contributions are treated in the resonant time-blocking approximation, in analogy to the previously developed relativistic quasiparticle time-blocking approximation (RQTBA) in the neutral (non-isospin-flip) channel. The new method is called proton-neutron RQTBA (pn-RQTBA) and is applied to the Gamow-Teller resonance in a chain of neutron-rich nickel isotopes {sup 68-78}Ni. A strong fragmentation of the resonance along with quenching of the strength, as compared to pn-RQRPA, is obtained. Based on the calculated strength distribution, beta-decay half-lives of the considered isotopes are computed and compared to pn-RQRPA half-lives and to experimental data. It is shown that a considerable improvement of the half-life description is obtained in pn-RQTBA because of the spreading effects, which bring the lifetimes to a very good quantitative agreement with data. (orig.)
International Nuclear Information System (INIS)
Bedrosian, B.; Barbela, M.; Drenick, R.F.; Tsirk, A.
1980-10-01
The critical excitation method provides a new, alternative approach to methods presently used for seismic analysis of nuclear power plant structures. The critical excitation method offers the advantages that: (1) it side-steps the assumptions regarding the probability distribution of ground motions, and (2) it does not require an artificial, and to some extent arbitrarily generated, time history of ground motion, both features to which structural integrity analyses are sensitive. Potential utility of the critical excitation method is studied from the user's viewpoint. The method is reviewed and compared with the response spectrum method used in current practice, utilizing the reactor buildings of a PWR and a BWR plant in case studies. Two types of constraints on critical excitation were considered in the study. In one case, only an intensity limit was used. In the other case, imposition of an intensity limit together with limits on the maximum acceleration and/or velocity for the critical excitation is considered
Interference of Coulomb and nuclear excitation in inelastic scattering of 20Ne from 40Ca
International Nuclear Information System (INIS)
Ratel, Guy.
1976-01-01
Angular distributions at 54 and 63MeV and excitation functions from 35 to 95MeV for the elastic and inelastic scattering of 20 Ne by 40 Ca have been measured. Experimental data for the inelastic scattering leading to the 20 Ne (2 + , 1.63MeV) state show a characteristic minimum for the angular distributions and excitation functions. This phenomenon was explained by an interference effect between Coulomb and nuclear excitation amplitudes with the DWBA and the coupled-channel formalism. The existence of this interference minimum could be explained only by assuming a nuclear deformation stronger than these obtained with light ion scattering. However a small shift between the experimental data and theoretical curves suggests that effects of a stronger complex coupling or nuclear reorientation due to the large quadrupole moment of 20 Ne must be included [fr
Microscopic theory of nuclear collective rotation
International Nuclear Information System (INIS)
Wunner, G.; Ruder, H.; Herold, H.; Reinecke, M.
1980-01-01
Various methods for calculating nuclear moments of inertia have been investigated, from the point of view of their possible connection with special choices of collective variables, using the method of specific decoupling (SD), which introduces a body-fixed frame in such a way that, for a given internal state, the best possible decoupling of internal and collective motion is obtained, and which for any definition of the body-fixed frame provides a well defined expression for the moment of inertia. The internal degrees of freedom are described using (1) intrinsic densities and (2) intrinsic wavefunctions. It is shown that several frequently used formulae for calculating the moment of inertia can be traced back to specific definitions of the internal frame and the extremum principle of SD makes possible a lucid evaluation of the magnitudes of these moments of inertia relative to each other as well as with respect to the corresponding values of the rigid and the irrotational moments of inertia. (author)
Evolution of nuclear collectivity at high spins and temperatures
International Nuclear Information System (INIS)
Baktash, C.
1989-01-01
In the past few years, we have utilized the Spin Spectrometer and a variety of complementary probes (continuum γrays, proton-γ coincidence spectroscopy and γ decay of GDR) to study the nuclear response to the DIFFERENTIAL effects of increasing spin and temperature for constant values of excitation energy or spin, respectively. In this paper we shall describe two of the experiments that trace the properties of rapidly-rotating nuclei at small to moderate excitation energies. 22 refs., 7 figs
Influence of nuclear dissipation on fission dynamics of the excited ...
Indian Academy of Sciences (India)
A stochastic approach to fission dynamics based on two-dimensional Langevin equations was applied to calculate the anisotropy of the fission fragments angular distribution and average pre-scission neutron multiplicities for the compound nucleus 248Cf formed in the $${16}$O+$^{232}$Th reactions. Postsaddle nuclear ...
‘Which-way’ collective atomic spin excitation among atomic ensembles by photon indistinguishability
International Nuclear Information System (INIS)
Zhang Guowan; Bian Chenglin; Chen, L Q; Ou, Z Y; Zhang Weiping
2012-01-01
In spontaneous Raman scattering in an atomic ensemble, a collective atomic spin wave is created in correlation with the Stokes field. When the Stokes photons from two or more such atomic ensembles are made indistinguishable, a ‘which-way’ collective atomic spin excitation is generated among the independent atomic ensembles. We demonstrate this phenomenon experimentally by reading out the atomic spin excitations and observing interference between the read-out beams. When a single-photon projective measurement is made on the indistinguishable Stokes photons, this simple scheme can be used to entangle independent atomic ensembles. Compared to other currently used methods, this scheme can be easily scaled up and has greater efficiency. (paper)
Collective excitations in a superfluid of color-flavor locked quark matter
International Nuclear Information System (INIS)
Fukushima, Kenji; Iida, Kei
2005-01-01
We investigate collective excitations coupled with baryon density in a system of massless three-flavor quarks in the collisionless regime. By using the Nambu-Jona-Lasinio (NJL) model in the mean-field approximation, we field-theoretically derive the spectra both for the normal and color-flavor locked (CFL) superfluid phases at zero temperature. In the normal phase, we obtain usual zero sound as a low-lying collective mode in the particle-hole (vector) channel. In the CFL phase, the nature of collective excitations varies in a way dependent on whether the excitation energy, ω, is larger or smaller than the threshold given by twice the pairing gap Δ, at which pair excitations with nonzero total momentum become allowed to break up into two quasiparticles. For ω H =1/√(3) in the low momentum regime; the decay constant f H obtained in the NJL model is identical with the QCD result obtained in the mean-field approximation. We also find that, as the momentum of the phonon increases, the excitation energy goes up and asymptotically approaches ω=2Δ. Above the threshold for pair excitations (ω>2Δ), zero sound manifests itself in the vector channel. By locating the zero sound pole of the vector propagator in the complex energy plane, we investigate the attenuation and energy dispersion relation of zero sound. In the long wavelength limit, the phonon mode, the only low-lying excitation, has its spectral weight in the H channel alone, while the spectral function vanishes in the vector channel. This is due to nontrivial mixing between the H and vector channels in the superfluid medium. We finally extend our study to the case of nonzero temperature. We demonstrate how Landau damping smears the phonon peak in the finite temperature spectral function. We find a pure imaginary pole of the H propagator in the complex energy plane, which can be identified as a diffusive mode responsible for the Landau damping. From the pole position we derive the thermal diffusion constant
On the theory of deuteron disintegration with collective states excitation in nuclei
International Nuclear Information System (INIS)
Evlanov, M.V.
1981-01-01
Differential cross sections of diffraction disintegration of deuterons with excitation of collective states in nuclei have been theoretically investigated. Effects of nucleon-nucleon interaction as well as smearing of nucleus boundary on differential characteristics of deuteron disintegration accompanying with change in state of target- nuclei have been studied. Spectra of protons liberated during the reaction of 2 + level deuteron disintegration in 114 Cd nucleus are presented [ru
Nuclear excitations in plasmas: the case of 84mRb
International Nuclear Information System (INIS)
Denis-Petit, David
2014-01-01
This experimental and theoretical work deals with the Nuclear Excitation by Electron Transition (NEET) process which involves a coupling between the nucleus and its electron cloud. In this process, an electron de-excitation can induce a nuclear excitation if the atomic and nuclear transitions are resonant and have the same multipolarity. This process could be observed in a laser created plasma of 84 Rb because this nucleus has a low energy transition (around 3 keV) between the isomeric state (J π = 6 - ,T 1/2 = 20,26 m) and the J π p= 5 - (T 1/2 = 9 ns) state. To evaluate a NEET excitation rate, the atomic states in plasma must be described and the nuclear transition must be precisely characterised. To describe the atomic states in plasma, a method based on a MCDF (Multi-Configuration Dirac-Fock) code was developed. This one uses a procedure to select the most probable atomic configurations according to the plasma properties. This method was checked by the interpretation of a X-rays spectrum emitted by a Rb plasma. This plasma was produced by the PHELIX laser of the GSI laboratory at an intensity of 6*10 14 W/cm 2 . The energy of the nuclear transition between the states 6 - and 5 - was not accurate enough for the NEET rate evaluation. Two γ-rays spectroscopy experiments were conducted at the ELSA accelerator from CEA/DAM/DIF and at the Tandem accelerator from the Orsay laboratory. The accuracy of the nuclear transition energy was improved of more than one order of magnitude. In this work, the NEET rate was evaluated to predict an experiment. The Rb plasma must have a high temperature (around 400 eV) to obtain a sufficient number of excited isomers and therefore to make possible the detection. (author)
The nuclear fluctuation width and the method of maxima in excitation curves
International Nuclear Information System (INIS)
Burjan, V.
1988-01-01
The method of counting maxima of excitation curves in the region of the occurrence of nuclear cross section fluctuations is extended to the case of the more realistic maxima defined as a sequence of five points instead of the simpler and commonly used case of a sequence of three points of an excitation curve. The dependence of the coefficient b (5) (κ), relating the number of five-point maxima and the mean level width Γ of the compound nucleus, on the relative distance K of excitation curve points is calculated. The influence of the random background on the coefficient b (5) (κ) is discussed and a comparison with the properties of the three-point coefficient b (3) (κ) is made - also in connection with the contribution of the random background. The calculated values of b (5) (κ) are well reproduced by the data obtained from the analysis of artificial excitation curves. (orig.)
Three-mode resonant coupling of collective excitations in a Bose-Einstein condensate
International Nuclear Information System (INIS)
Ma Yongli; Huang, Guoxiang; Hu Bambi
2005-01-01
We make a systematic study of the resonant mode coupling of the collective excitations at zero temperature in a Bose-Einstein condensate (BEC). (i) Based on the Gross-Pitaevskii equation we derive a set of nonlinearly coupled envelope equations for a three-mode resonant interaction (TMRI) by means of a method of multiple scales. (ii) We calculate the coupling matrix elements for the TMRI and show that the divergence appearing in previous studies can be eliminated completely by using a Fetter-like variational approximation for the ground-state wave function of the condensate. (iii) We provide the selection rules in mode-mode interaction processes [including TMRI and second-harmonic generation (SHG)] according to the symmetry of the excitations. (iv) By solving the nonlinearly coupled envelope equations we obtain divergence-free nonlinear amplitudes for the TMRI and SHG processes and show that our theoretical results on the shape oscillations of the condensate agree well with the experimental ones. We suggest also an experiment to check the theoretical prediction of the present study on the TMRI of collective excitations in a BEC
Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei
Directory of Open Access Journals (Sweden)
Leoni S.
2016-01-01
Full Text Available The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as 47,49Ca, 133Sb and 210Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of 235U and 241Pu targets, with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of 133Sb, a new microscopic “hybrid” model is introduced: it is based on the coupling between core excitations (both collective and non-collective of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.
Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei
Leoni, S.
2016-05-01
The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as 47,49Ca, 133Sb and 210Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of 235U and 241Pu targets), with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of 133Sb, a new microscopic "hybrid" model is introduced: it is based on the coupling between core excitations (both collective and non-collective) of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.
On the role of memory effects for dissipation and diffusion in slow collective nuclear motion
International Nuclear Information System (INIS)
Cassing, W.; Noerenberg, W.
1983-01-01
The energy dissipation in slow collective nuclear motion is viewed as a combined effect of a diabatic production of particle-hole excitations, leading to a conservative storage of collective energy, and a subsequent equilibration due to residual two-body collisions. The effective equation of motion for the collective degree of freedom turns out to be nonlocal in time due to the large mean free path of the nucleons and allows for a simultaneous description of two different attitudes of nuclear matter. The elastic response of heavy nuclei for ''fast'' collective motion switches over to pure friction for very slow collective motion. The time development of the fluctuations in the velocities may show oscillations for times comparable to the local equilibration time and hence, is qualitatively different from the classical limit. A first application of the diabatic dynamical approach is made for the quadrupole motion within a diabatic deformed harmonic oscillator basis. (orig.)
Analysis of collective excitations of rapidly rotating nuclei in an oscillator potential
International Nuclear Information System (INIS)
Akbarov, A.; Ignatyuk, A.V.; Mikhailov, I.N.; Molina, K.L.; Nazmitdinov, R.G.; Janssen, D.
1981-01-01
The spectrum of positive-parity collective excitations is analyzed in the random phase approximation for a wide range of angular momenta. The Hamiltonian of the model is taken in the form of a spherical harmonic-oscillator potential and isoscalar quadrupole forces. This model permits a description of the known data on the position of a giant quadrupole resonance for small spins and allows the variation of the resonance characteristics to be followed as the spin increases. It is shown that as the rotation velocity increases the energy of one of the branches of the resonance decreases to zero while the state remains strongly collectivized. The model also reproduces the low energy vibration mode which is related to the precession mode. The excitation energy and the B(E2) factor corresponding to this mode differ considerably from the estimates obtained in the rigid rotator model
International Nuclear Information System (INIS)
Ghosh, Tarun Kanti
2002-01-01
We study the collective excitations of a neutral atomic Bose-Einstein condensate with gravitylike 1/r interatomic attraction induced by an electromagnetic wave. Using the time-dependent variational approach, we derive an analytical spectrum for monopole and quadrupole mode frequencies of a gravitylike self-bound Bose condensed state at zero temperature. We also analyze the excitation frequencies of the Thomas-Fermi-gravity (TF-G) and gravity (G) regimes. Our result agrees excellently with that of Giovanazzi et al. [Europhysics Lett., 56, 1 (2001)], which is obtained within the sum-rule approach. We also consider the vortex state. We estimate the superfluid coherence length and the critical angular frequencies to create a vortex around the z axis. We find that the TF-G regime can exhibit the superfluid properties more prominently than the G regime. We find that the monopole mode frequency of the condensate decreases due to the presence of a vortex
Directory of Open Access Journals (Sweden)
Manvir S. Kushwaha
2013-04-01
intrasubband and intersubband single-particle as well as collective excitations], the loss functions for the IES and the Raman intensity for the ILS. We observe that it is the collective (plasmon excitations that largely contribute to the predominant peaks in the energy-loss and the Raman spectra. The inductive reasoning is that the IES can be a potential alternative of the overused ILS for investigating collective excitations in quantum wires. We trust that this research work shall be useful to all – from novice to expert and from theorist to experimentalist – who believe in the power of traditional science.
Isomer depletion as experimental evidence of nuclear excitation by electron capture
Chiara, C. J.; Carroll, J. J.; Carpenter, M. P.; Greene, J. P.; Hartley, D. J.; Janssens, R. V. F.; Lane, G. J.; Marsh, J. C.; Matters, D. A.; Polasik, M.; Rzadkiewicz, J.; Seweryniak, D.; Zhu, S.; Bottoni, S.; Hayes, A. B.; Karamian, S. A.
2018-02-01
The atomic nucleus and its electrons are often thought of as independent systems that are held together in the atom by their mutual attraction. Their interaction, however, leads to other important effects, such as providing an additional decay mode for excited nuclear states, whereby the nucleus releases energy by ejecting an atomic electron instead of by emitting a γ-ray. This ‘internal conversion’ has been known for about a hundred years and can be used to study nuclei and their interaction with their electrons. In the inverse process—nuclear excitation by electron capture (NEEC)—a free electron is captured into an atomic vacancy and can excite the nucleus to a higher-energy state, provided that the kinetic energy of the free electron plus the magnitude of its binding energy once captured matches the nuclear energy difference between the two states. NEEC was predicted in 1976 and has not hitherto been observed. Here we report evidence of NEEC in molybdenum-93 and determine the probability and cross-section for the process in a beam-based experimental scenario. Our results provide a standard for the assessment of theoretical models relevant to NEEC, which predict cross-sections that span many orders of magnitude. The greatest practical effect of the NEEC process may be on the survival of nuclei in stellar environments, in which it could excite isomers (that is, long-lived nuclear states) to shorter-lived states. Such excitations may reduce the abundance of the isotope after its production. This is an example of ‘isomer depletion’, which has been investigated previously through other reactions, but is used here to obtain evidence for NEEC.
Simulation of kinetic processes in the nuclear-excited helium non-ideal dusty plasma
International Nuclear Information System (INIS)
Budnik, A.P.; Kosarev, V.A.; Rykov, V.A.; Fortov, V.E.; Vladimirov, V.I.; Deputatova, L.V.
2009-01-01
The paper is devoted to the studying of kinetic processes in the nuclear-excited plasma of the helium gas with the fine uranium (or its chemical compounds) particles admixture. A new theoretical model for the mathematical simulation of the kinetic processes in dusty plasma of helium gas was developed. The main goal of this investigation is to determine possibilities of a creation of non-ideal dusty plasma, containing nano- and micro-particles, and excited by fission fragments (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Gritsev, Vladimir; Demler, Eugene; Lukin, Mikhail; Polkovnikov, Anatoli
2007-11-16
We study the problem of rapid change of the interaction parameter (quench) in a many-body low-dimensional system. It is shown that, measuring the correlation functions after the quench, the information about a spectrum of collective excitations in a system can be obtained. This observation is supported by analysis of several integrable models and we argue that it is valid for nonintegrable models as well. Our conclusions are supplemented by performing exact numerical simulations on finite systems. We propose that measuring the power spectrum in a dynamically split 1D Bose-Einsten condensate into two coupled condensates can be used as an experimental test of our predictions.
Energetic M1 transitions as a probe of nuclear collectivity at high temperatures
International Nuclear Information System (INIS)
Baktash, C.
1987-01-01
At ORNL, we have recently utilized the Spin Spectrometer setup to investigate the differential effects of increasing spin and excitation energy on nuclear shape and collectivity in 158 Yb. Along the yrast line of this and other N = 88 nuclei, weakly prolate shapes gradually give way to triaxial, and then finally to non-collective oblate shapes as the spin approaches 40 h-bar. However, above the yrast line, large deformation and collectivity once again sets in. This is evidenced by the emergence of a broad quadrupole structure (E/sub γ/ ≅ 1.2 MeV) in the continuum gamma-ray spectra that grows with increasing temperature. The short (sub ps) lifetimes of these transitions attest to the collective nature of these structures. The emergence and growth of the quadrupole structure at high excitation energies is closely correlated with the appearance of energetic (E/sub γ/ ≅ 2.5 MeV), fast M1 transitions which form another broad structure in the continuum spectra. From the centroid of the M1 bump, a quadrupole deformation parameter of 0.35 is inferred. Because of this sensitivity, these energetic M1 transitions provide a unique probe of nuclear shape in the excitation energy range of ≅ 3 to 10 MeV. 6 refs., 2 figs
Collective excitations in circular atomic configurations and single-photon traps
International Nuclear Information System (INIS)
Hammer, Hanno
2004-01-01
Correlated excitations in a plane circular configuration of identical atoms with parallel dipole moments are investigated. The collective energy eigenstates, which are formally identical to Frenkel excitons, can be computed together with their level shifts and decay rates by decomposing the atomic state space into carrier spaces for the irreducible representations of the symmetry group Z N of the circle. It is shown that the index p of these representations can be used as a quantum number analogously to the orbital angular momentum quantum number l in hydrogenlike systems. Just as the hydrogen s states are the only electronic wave functions which can occupy the central region of the Coulomb potential, the quasiparticle corresponding to a collective excitation of the atoms in the circle can occupy the central atom only for vanishing Z N quantum number p. If a central atom is present, the p=0 state splits into two and shows level crossing at certain radii; in the regions between these radii, damped quantum beats between two 'extreme' p=0 configurations occur. The physical mechanisms behind super- and subradiance at a given radius are discussed. It is shown that, beyond a certain critical number of atoms in the circle, the lifetime of the maximally subradiant state increases exponentially with the number of atoms in the configuration, making the system a natural candidate for a single-photon trap
Full nuclear field theory treatment of two-particle-one-hole-excitations
International Nuclear Information System (INIS)
Silvestre-Brac, B.; Liotta, R.J.
1981-01-01
The nuclear field theory series is summed up to all orders of perturbation theory including only Tamm-Dancoff vertices for the case of two-particle-one-hole-excitations. It is found that the theory gives the same results as those provided by the shell-model method, but only if all possible basis states are included in the formalism. Applicability of the theory is discussed in a simple model
Coupling of mass and charge distributions for low excited nuclear fission
International Nuclear Information System (INIS)
Salamatin, V.S.; )
2000-01-01
The simple model for calculation of charge distributions of fission fragments for low exited nuclear fission from experimental mass distributions is offered. The model contains two parameters, determining amplitude of even-odd effect of charge distributions and its dependence on excitation energy. Results for reactions 233 U(n th ,f), 235 U(n th ,f), 229 Th(n th ,f), 249 Cf(n th ,f) are spent [ru
The structure of nuclear states at low, intermediate and high excitation energies
International Nuclear Information System (INIS)
Soloviev, V.G.
1976-01-01
It is shown that within the model based on the quasiparticle-phonon interaction one can obtain the description of few-quasiparticle components of nuclear states at low, intermediate and high excitation energies. For the low-lying states the energy of each level is calculated. The few-quasiparticle components at intermediate and high excitation energies are represented to be averaged in certain energy intervals and their characteri stics are given as the corresponding strength functions. The fragmentation of single-particle states in deformed nuclei is studied. It is shown that in the distribution of the single-particle strength alongside with a large maximum there appear local maxima and the distribution itself has a long tail. The dependence of neutron strength functions on the excitation energy is investigated for the transfer reaction of the type (d,p) and (d,t). The s,- p,- and d-wave neutron strength functions are calculated at the neutron binding energy Bn. A satisfactory agreement with experiment is obtained. The energies and Elambda-strength functions for giant multipole resonances in deformed nuclei are calculated. The energies of giant quadrupole and octupole resonances are calculated. Their widths and fine structure are being studied. It is stated that to study the structure of highly excited states it is necessary to find the values of many-quasiparticle components of the wave functions. The ways of experimental determination of these components based on the study of γ-transitions between highly excited states are discussed
Improved description of the fragmentation of nuclear collective states
International Nuclear Information System (INIS)
Soloviev, V.G.
1984-01-01
A mathematical method is deveioped for a more accurate description of the fragmentation of one-phonon states forming giant resonances. The method consists in that the one-phonon states already fragmented are used in the two-phonon terms of wave functions. Strength functions are obtained for the exci excitation of collective charge-exchange states ano giant resonances in spherical nuclei
Collective excitations and supersolid behavior of bosonic atoms inside two crossed optical cavities
Lang, J.; Piazza, F.; Zwerger, W.
2017-12-01
We discuss the nature of symmetry breaking and the associated collective excitations for a system of bosons coupled to the electromagnetic field of two optical cavities. For the specific configuration realized in a recent experiment at ETH [1, 2], we show that, in absence of direct intercavity scattering and for parameters chosen such that the atoms couple symmetrically to both cavities, the system possesses an approximate U(1) symmetry which holds asymptotically for vanishing cavity field intensity. It corresponds to the invariance with respect to redistributing the total intensity I={I}1+{I}2 between the two cavities. The spontaneous breaking of this symmetry gives rise to a broken continuous translation-invariance for the atoms, creating a supersolid-like order in the presence of a Bose-Einstein condensate. In particular, we show that atom-mediated scattering between the two cavities, which favors the state with equal light intensities {I}1={I}2 and reduces the symmetry to {{Z}}2\\otimes {{Z}}2, gives rise to a finite value ˜ \\sqrt{I} of the effective Goldstone mass. For strong atom driving, this low energy mode is clearly separated from an effective Higgs excitation associated with changes of the total intensity I. In addition, we compute the spectral distribution of the cavity light field and show that both the Higgs and Goldstone mode acquire a finite lifetime due to Landau damping at non-zero temperature.
Collective excitations and the nature of Mott transition in undoped gapped graphene
International Nuclear Information System (INIS)
Jafari, S A
2012-01-01
The particle-hole continuum (PHC) for massive Dirac fermions provides an unprecedented opportunity for the formation of two collective split-off states, one in the singlet and the other in the triplet (spin-1) channel, when the short-range interactions are added to the undoped system. Both states are close in energy and are separated from the continuum of free particle-hole excitations by an energy scale of the order of the gap parameter Δ. They both disperse linearly with two different velocities, reminiscent of spin-charge separation in Luttinger liquids. When the strength of Hubbard interactions is stronger than a critical value, the velocity of singlet excitation, which we interpret as a charge composite boson, becomes zero and renders the system a Mott insulator. Beyond this critical point the low-energy sector is left with a linearly dispersing triplet mode - a characteristic of a Mott insulator. The velocity of the triplet mode at the Mott criticality is twice the velocity of the underlying Dirac fermions. The phase transition line in the space of U and Δ is in qualitative agreement with our previous dynamical mean field theory calculations. (paper)
Open questions on nuclear collective motion
Energy Technology Data Exchange (ETDEWEB)
Frauendorf, S., E-mail: sfrauend@nd.edu [Department of Physics, University Notre Dame, IN 46557 (United States)
2016-07-07
The status of the macroscopic and microscopic description of the collective quadrupole modes is reviewed, where limits due to non-adiabaticity and decoherence are exposed. The microscopic description of the yrast states in vibrator-like nuclei in the framework of the rotating mean field is presented.
Excitation energy and angular momentum dependence of the nuclear level densities
International Nuclear Information System (INIS)
Razavi, R.; Kakavand, T.; Behkami, A. N.
2007-01-01
We have investigated the excitation energy (E) dependence of nuclear level density for Bethe formula and constant temperature model. The level density parameter aa nd the back shifted energy from the Bethe formula are obtained by fitting the complete level schemes. Also the level density parameters from the constant temperature model have been determined for several nuclei. we have shown that the microscopic theory provides more precise information on the nuclear level densities. On the other hand, the spin cut-off parameter and effective moment of inertia are determined by studying of the angular momentum (J) dependence of the nuclear level density, and effective moment of inertia is compared with rigid body value.
Coupled spin and charge collective excitations in a spin polarized electron gas
International Nuclear Information System (INIS)
Marinescu, D.C.; Quinn, J.J.; Yi, K.S.
1997-01-01
The charge and longitudinal spin responses induced in a spin polarized quantum well by a weak electromagnetic field are investigated within the framework of the linear response theory. The authors evaluate the excitation frequencies for the intra- and inter-subband transitions of the collective charge and longitudinal spin density oscillations including many-body corrections beyond the random phase approximation through the spin dependent local field factors, G σ ± (q,ω). An equation-of-motion method was used to obtain these corrections in the limit of long wavelengths, and the results are given in terms of the equilibrium pair correlation function. The finite degree of spin polarization is shown to introduce coupling between the charge and spin density modes, in contrast with the result for an unpolarized system
Collective excitations in the Penson-Kolb model: A generalized random-phase-approximation study
International Nuclear Information System (INIS)
Roy, G.K.; Bhattacharyya, B.
1997-01-01
The evolution of the superconducting ground state of the half-filled Penson-Kolb model is examined as a function of the coupling constant using a mean-field approach and the generalized random phase approximation (RPA) in two and three dimensions. On-site singlet pairs hop to compete against single-particle motion in this model, giving the coupling constant a strong momentum dependence. There is a pronounced bandwidth enhancement effect that converges smoothly to a finite value in the strong-coupling (Bose) regime. The low-lying collective excitations evaluated in generalized RPA show a linear dispersion and a gradual crossover from the weak-coupling (BCS) limit to the Bose regime; the mode velocity increases monotonically in sharp contrast to the attractive Hubbard model. Analytical results are derived in the asymptotic limits. copyright 1997 The American Physical Society
Nuclear collective vibrations in extended mean-field theory
Energy Technology Data Exchange (ETDEWEB)
Lacroix, D. [Lab. de Physique Corpusculaire/ ENSICAEN, 14 - Caen (France); Ayik, S. [Tennessee Technological Univ., Cookeville, TN (United States); Chomaz, Ph. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)
2003-07-01
The extended mean-field theory, which includes both the incoherent dissipation mechanism due to nucleon-nucleon collisions and the coherent dissipation mechanism due to coupling to low-lying surface vibrations, is briefly reviewed. Expressions of the strength functions for the collective excitations are presented in the small amplitude limit of this approach. This fully microscopic theory is applied by employing effective Skyrme forces to various giant resonance excitations at zero and finite temperature. The theory is able to describe the gross properties of giant resonance excitations, the fragmentation of the strength distributions as well as their fine structure. At finite temperature, the success and limitations of this extended mean-field description are discussed. (authors)
Kadhane, U; Misra, D; Singh, Y P; Tribedi, Lokesh C
2003-03-07
Projectile deexcitation Lyman x-ray emission following electron capture and K excitation has been studied in collisions of bare and Li-like sulphur ions (of energy 110 MeV) with fullerenes (C(60)/C(70)) and different gaseous targets. The intensity ratios of different Lyman x-ray lines in collisions with fullerenes are found to be substantially lower than those for the gas targets, both for capture and excitation. This has been explained in terms of a model based on "solidlike" effect, namely, wakefield induced stark mixing of the excited states populated via electron capture or K excitation: a collective phenomenon of plasmon excitation in the fullerenes under the influence of heavy, highly charged ions.
Light particle emission as a probe of reaction mechanism and nuclear excitation
International Nuclear Information System (INIS)
Guerreau, D.
1989-01-01
The central part of these lectures will be dealing with the problem of energy dissipation. A good understanding of the mechanisms for the dissipation requires to study both peripheral and central collisions or, in other words, to look at the impact paramenter dependence. This should also provide valuable information on the time scale. In order to probe the reaction mechanism and nuclear excitation, one of the most powerful tool is unquestionably the observation of light particle emission, including neutrons and charged particles. Several examples will be discussed related to peripheral collisions (the fate of transfer reactions, the excitation energy generation, the production of projectile-like fragments) as well as inner collisions for which extensive studies have demonstrated the strength of intermediate energy heavy ions for the production of very hot nuclei and detailed study of their decay properties
Exotic nuclear structures and decays: new nuclear collective phenomena
International Nuclear Information System (INIS)
Hamilton, J.H.
1986-01-01
Studies of the properties of exotic nuclei have revealed a surprising richness and diversity in their shapes, structures, and decay modes far exceeding our understandings and expectations of even a decay ago. From studies of far-off-stability exotic nuclei have come evidence for the coexistence of different nuclear shapes in the same nucleus, new regions of unusually large deformation, new ground-state phase transitions from one shape to another, new magic numbers but now for deformed shapes, and for the importance of reinforcing shell gaps. New exotic decay modes include a wide variety of beta delayed particle emission and heavy cluster emissions such as 14 C and 24 Ne. The new deformed magic numbers of 38 and 60 seen far off stability clearly support that there are likely other ''magic'' numbers for protons and neutrons which give stability to different deformed shapes. Perhaps these other new magic shell gap numbers at large deformation could influence the sticking of two very heavy nuclei in collisions such as U on Cm. Finally, another area which could have a bearing on the formation, motions, and structures of giant nuclear systems involves the recent observation of very energetic, light particle (proton, alpha) emission with up to 50% and more of the total incoming energy in a collision, for example in 300 MeV 32 S on Ta. 43 refs., 11 figs., 2 tabs
Nuclear shapes and nuclear structure at low excitation energies. Abstracts of contributed papers
International Nuclear Information System (INIS)
Dykstra, F.; Goutte, D.; Sauvage, J.; Vergnes, M.
1994-01-01
103 papers are presented on recent theoretical and experimental results on nuclear structure investigation. Short communications were published in this volume, all of which were indexed separately for the INIS database. (R.P.)
Preparations for an optical access to the lowest nuclear excitation in {sup 229}Th
Energy Technology Data Exchange (ETDEWEB)
Wense, Lars v.d.; Seiferle, Benedict; Thirolf, Peter G. [Ludwig-Maximilians-Universitaet Muenchen (Germany); Laatiaoui, Mustapha [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany)
2015-07-01
The isomeric lowest excited nuclear level of {sup 229}Th has been indirectly measured to be 7.6±0.5 eV (163±11 nm). This low transition energy, compared to energies typically involved in nuclear processes, would allow for the application of laser-spectroscopic methods. Also considering the isomeric lifetime of the excited state (estimated to be 10{sup 3} to 10{sup 4} s), which leads to an extremely sharp linewidth of Δω/ω ∝ 10{sup -20}, the isomer becomes a strong candidate for a nuclear-based frequency standard. In order to directly detect the isomeric ground-state decay and improve the accuracy of its energy as a prerequisite for an all-optical control, {sup 229m}Th is populated via a 2% decay branch in the α decay of {sup 233}U. The Thorium ions are extracted and cooled with the help of a buffer-gas stopping cell and an RFQ-cooler. In order to suppress accompanying α decay chain products other than {sup 229}Th, a quadrupole mass spectrometer (QMS) is used. Following the QMS, the Thorium isomeric decay is expected to be detectable. Internal conversion as well as photonic decay is probed via different detection techniques. Latest results are presented.
Energy Technology Data Exchange (ETDEWEB)
Gulshani, P., E-mail: matlap@bell.net [NUTECH Services, 3313 Fenwick Crescent, Mississauga, Ontario, L5L 5N1 (Canada)
2016-07-07
We derive a microscopic version of the successful phenomenological hydrodynamic model of Bohr-Davydov-Faessler-Greiner for collective rotation-vibration motion of an axially symmetric deformed nucleus. The derivation is not limited to small oscillation amplitude. The nuclear Schrodinger equation is canonically transformed to collective co-ordinates, which is then linearized using a constrained variational method. The associated constraints are imposed on the wavefunction rather than on the particle co-ordinates. The approach yields three self-consistent, time-reversal invariant, cranking-type Schrodinger equations for the rotation-vibration and intrinsic motions, and a self-consistency equation. For harmonic oscillator mean-field potentials, these equations are solved in closed forms for excitation energy, cut-off angular momentum, and other nuclear properties for the ground-state rotational band in some deformed nuclei. The results are compared with measured data.
The effect of a neutrino magnetic moment on nuclear excitation processes
International Nuclear Information System (INIS)
Dodd, A.C.; Papageorgiu, E.; Ranfone, S.
1991-01-01
It is shown that the MeV-range neutrinos with a magnetic moment of ≅ 10 -11 Bohr magnetons would excite nuclei, like 12 C, with cross sections comparable to those obtained in the Standard Model. This implies the possibility of improving the present experimental bounds on the magnetic moment of any flavour of neutrinos by one order of magnitude. Such a magnetic moment would also enhance the coherent neutrino-nuclear scattering in low-temperature detectors, enabling them to set comparable limits. (author)
Nuclear-charge polarization at scission in fission from moderately excited light-actinide nuclei
International Nuclear Information System (INIS)
Nishinaka, Ichiro
2009-01-01
Fragment mass yields and the average neutron multiplicity in the proton-induced fission of 232 Th and 238 U were measured by a double time-of-flight method. The most probable charges of secondary fragments were evaluated from the fragment mass yields measured by the double time-of-flight method and the fractional cumulative and independent yields reported in literature. The nuclear-charge polarization of primary fragments at scission was obtained by correcting the most probable charge of secondary fragments for neutron evaporation. The results show that the nuclear-charge polarization at scission is associated with the liquid-drop properties of nuclei and the proton shell effect with Z = 50 of heavy fragments and that it is practically insensitive to mass and excitation energy of the fissioning nucleus in the region of light-actinide nuclei. (author)
Velocity fields and transition densities in nuclear collective modes
Energy Technology Data Exchange (ETDEWEB)
Stringari, S [Dipartimento di Matematica e Fisica, Libera Universita di Trento, Italy
1979-08-13
The shape of the deformations occurring in nuclear collective modes is investigated by means of a microscopic approach. Analytical solutions of the equations of motion are obtained by using simplified nuclear potentials. It is found that the structure of the velocity field and of the transition density of low-lying modes is considerably different from the predictions of irrotational hydrodynamic models. The low-lying octupole state is studied in particular detail by using the Skyrme force.
Concluding remarks of international symposium on highly excited states in nuclear reactions
Energy Technology Data Exchange (ETDEWEB)
Bernstein, A. M.; Ikegami, H.; Muraoka, M. [eds.
1980-01-01
This is the concluding remarks in the international symposium on highly excited states in nuclear reactions. The remarks concentrate on the giant quadrupole states. In the framework of the distorted wave Born approximation (DWB), the differential cross section can be deduced. The relevant transition matrix elements are defined, and the quantities which are measured in inelastic hadron (h, h') reactions are shown. These are used to obtain both neutron and proton transition multipole matrix elements. This is equivalent to make the isospin decomposition of the electromagnetic transition matrix elements. The ratios of the transition matrix elements of neutrons and protons of the lowest 2/sup +/ states in even-even single closed shell nuclei are evaluated and compared with experimental results. For each nucleus, the consistency between various measurements is generally good. The effect of the virtual excitation of giant 2/sup +/ states into the ground and first excited states of even-even nuclei is discussed. The accuracy of (h, h') results can be tested.
International Nuclear Information System (INIS)
Kuriyama, Atsushi; Okamoto, Ryoji; Marumori, Toshio; Matsuyanagi, Kenichi.
1975-01-01
With the aid of microscopic theory of collective excitations in spherical odd-mass nuclei proposed by Kuriyama, Marumori and Matsuyanagi, structures of low-lying collective 5/2 + states in odd-mass I, Cs and La isotopes and of collective 3/2 + states in odd-mass Mo and Ru isotopes are investigated. These collective 5/2 + and 3/2 + states, which are hard to understand within the framework of the conventional quasi-particle-phonon-coupling theory, are identified as a new kind of fermion-type collective excitation mode. The change in microscopic structure of these states depending on the mass number is also investigated in relation with the shell structure. (auth.)
The collective Lamb shift in nuclear γ-ray superradiance
International Nuclear Information System (INIS)
Röhlsberger, Ralf
2012-01-01
The electromagnetic transitions of Mössbauer nuclei provide almost ideal two-level systems to transfer quantum optical concepts into the regime of hard x-rays. If many identical atoms collectively interact with a resonant radiation field, one observes (quantum) optical properties that are strongly different from those of a single atom. The most prominent effect is the broadening of the resonance line known as collective enhancement, resulting from multiple scattering of real photons within the atomic ensemble. On the other hand, the exchange of virtual photons within the ensemble leads to a tiny energy shift of the resonance line, the collective Lamb shift, that remained experimentally elusive for a long time after its prediction. Here we illustrate how highly brilliant synchrotron radiation allows one to prepare superradiant states of excited Mössbauer nuclei, an important condition for observation of the collective Lamb shift.
Energy Technology Data Exchange (ETDEWEB)
Hellgartner, Stefanie Christine
2015-11-13
In this work, the N=40 subshell closure is investigated with two complementary methods using a radioactive {sup 72}Zn ISOLDE beam: One- and two-neutron transfer reactions and multiple Coulomb excitation. In the one-neutron transfer reaction, two new levels of {sup 73}Zn were discovered. The two-neutron transfer channel allowed to study the differential cross section of the ground state and the 2{sup +}{sub 1} state of {sup 74}Zn. In the Coulomb excitation experiment, the measured B(E2) values and quadrupole moments of {sup 72}Zn showed that the yrast states 0{sup +}{sub 1}, 2{sup +}{sub 1} and 4{sup +}{sub 1} are moderately collective. Contrary, the 0{sup +}{sub 2} state has a different structure, since it features a stronger closed N=40 configuration compared to the ground state.
International Nuclear Information System (INIS)
Frederick, B.deB.
1994-12-01
Nuclear magnetic resonance (NMR) spectroscopic imaging of 23 Na holds promise as a non-invasive method of mapping Na + distributions, and for differentiating pools of Na + ions in biological tissues. However, due to NMR relaxation properties of 23 Na in vivo, a large fraction of Na + is not visible with conventional NMR imaging methods. An alternate imaging method, based on stochastic excitation and oscillating gradients, has been developed which is well adapted to measuring nuclei with short T 2 . Contemporary NMR imaging techniques have dead times of up to several hundred microseconds between excitation and sampling, comparable to the shortest in vivo 23 Na T 2 values, causing significant signal loss. An imaging strategy based on stochastic excitation has been developed which greatly reduces experiment dead time by reducing peak radiofrequency (RF) excitation power and using a novel RF circuit to speed probe recovery. Continuously oscillating gradients are used to eliminate transient eddy currents. Stochastic 1 H and 23 Na spectroscopic imaging experiments have been performed on a small animal system with dead times as low as 25μs, permitting spectroscopic imaging with 100% visibility in vivo. As an additional benefit, the encoding time for a 32x32x32 spectroscopic image is under 30 seconds. The development and analysis of stochastic NMR imaging has been hampered by limitations of the existing phase demodulation reconstruction technique. Three dimensional imaging was impractical due to reconstruction time, and design and analysis of proposed experiments was limited by the mathematical intractability of the reconstruction method. A new reconstruction method for stochastic NMR based on Fourier interpolation has been formulated combining the advantage of a several hundredfold reduction in reconstruction time with a straightforward mathematical form
Photo-excited charge collection spectroscopy probing the traps in field-effect transistors
Im, Seongil; Kim, Jae Hoon
2013-01-01
Solid state field-effect devices such as organic and inorganic-channel thin-film transistors (TFTs) have been expected to promote advances in display and sensor electronics. The operational stabilities of such TFTs are thus important, strongly depending on the nature and density of charge traps present at the channel/dielectric interface or in the thin-film channel itself. This book contains how to characterize these traps, starting from the device physics of field-effect transistor (FET). Unlike conventional analysis techniques which are away from well-resolving spectral results, newly-introduced photo-excited charge-collection spectroscopy (PECCS) utilizes the photo-induced threshold voltage response from any type of working transistor devices with organic-, inorganic-, and even nano-channels, directly probing on the traps. So, our technique PECCS has been discussed through more than ten refereed-journal papers in the fields of device electronics, applied physics, applied chemistry, nano-devices and materia...
Density profiles and collective excitations of a trapped two-component Fermi vapour
International Nuclear Information System (INIS)
Amoruso, M.; Meccoli, I.; Minguzzi, A.; Tosi, M.P.
1999-08-01
We discuss the ground state and the small-amplitude excitations of a degenerate vapour of fermionic atoms placed in two hyperfine states inside a spherical harmonic trap. An equations-of-motion approach is set up to discuss the hydrodynamic dissipation processes from the interactions between the two components of the fluid beyond mean-field theory and to emphasize analogies with spin dynamics and spin diffusion in a homogeneous Fermi liquid. The conditions for the establishment of a collisional regime via scattering against cold-atom impurities are analyzed. The equilibrium density profiles are then calculated for a two-component vapour of 40 K atoms: they are little modified by the interactions for presently relevant values of the system parameters, but spatial separation of the two components will spontaneously arise as the number of atoms in the trap is increased. The eigenmodes of collective oscillation in both the total particle number density and the concentration density are evaluated analytically in the special case of a symmetric two-component vapour in the collisional regime. The dispersion relation of the surface modes for the total particle density reduces in this case to that of a one-component Fermi vapour, whereas the frequencies of all other modes are shifted by the interactions. (author)
The eyes, ears and collective voice for nuclear transport
International Nuclear Information System (INIS)
Green, L.
2000-01-01
Transport is a vital part of the nuclear industry and the safety record of radioactive materials transport across the world is excellent. This record is due primarily to well-founded regulations developed by such intergovernmental organisations as the International Atomic Energy Agency and the International Maritime Organisation. It is due, also, to the professionalism of those in the industry. Attitudes to nuclear transport are important. They have the potential, if not heeded, and not responded to sensitively and convincingly to make life very much more difficult for those committed to the safe, reliable and efficient transport of nuclear materials. What is required is a balanced situation, which takes account both of the public's attitudes and industry's need for an efficient operation. The voices of the nuclear transport industry and those who value the industry need to be heard. The World Nuclear Transport Institute was established to provide the nuclear transport industry with the collective eyes, ears and voice in the key intergovernmental organisations which are so important to it. The nuclear transport industry has a safety record which could be regarded as a model for the transport of dangerous goods of all kinds. The industry is situated within a comprehensive and strict regime of national and international standards and regulations. That is the message to be disseminated, and that is the commitment of the World Nuclear Transport Institute as it works to protect and to promote the safe, efficient and reliable transport of radioactive materials. (author)
Excited collective states of nuclei within Bohr Hamiltonian with Tietz-Hua potential
Energy Technology Data Exchange (ETDEWEB)
Chabab, M.; El Batoul, A.; Lahbas, A.; Oulne, M. [Cadi Ayyad University, High Energy Physics and Astrophysics Laboratory, Faculty of Sciences Semlalia, Marrakesh (Morocco); Hamzavi, M. [University of Zanjan, Department of Physics, Zanjan (Iran, Islamic Republic of)
2017-07-15
In this paper, we present new analytical solutions of the Bohr Hamiltonian problem that we derived with the Tietz-Hua potential, here used for describing the β-part of the nuclear collective potential plus that of the harmonic oscillator for the γ-part. Also, we proceed to a systematic comparison of the numerical results obtained with this kind of β-potential with others which are widely used in such a framework as well as with the experiment. The calculations are carried out for energy spectra and electromagnetic transition probabilities for γ-unstable and axially symmetric deformed nuclei. In the same frame, we show the effect of the shape flatness of the β-potential beyond its minimum on transition rates calculations. (orig.)
Linearised collective Schroedinger equation for nuclear quadrupole surface vibrations
International Nuclear Information System (INIS)
Greiner, M.; Heumann, D.; Scheid, W.
1990-11-01
The linearisation of the Schroedinger equation for nuclear quadrupole surface vibrations yields a new spin degree of freedom, which is called collective spin and has a value of 3/2. With the introduction of collective spin dependent potentials, this linearised Schroedinger equation is then used for the description of low energy spectra and electromagnetic transition probabilities of some even-odd Xe, Ir and Au nuclei which have a spin 3/2 in their groundstate. (orig.)
International Nuclear Information System (INIS)
Eliasson, G.L.
1987-01-01
The theory of collective excitations in semiconductor superlattices is formulated by using linear response theory. Different kinds of collective excitations in type I (GaAs-GaAlAs) and type II (GaSb-InAs) superlattices are surveyed. Special attention is paid to the presence of surface and finite-size effects. In calculating the dielectric matrix, the effect of different approximations of the system is discussed. The theory for inelastic length scattering (Raman scattering), and for Electron Energy Loss (EEL) due to collective excitations, is formulated. Calculations for several model systems are presented and the main features of the spectra are discussed. In part II the theory of collective excitations of a two-dimensional electron gas with a spatially periodic equilibrium density is formulated. As a first example a periodic array of two-dimensional electron gas strips with constant equilibrium density is studied. The integral equation that describes the charge fluctuations on the strips is derived and solved numerically. The spatial dependence of the density fluctuation across a single strip can be in the form of either propagating or evanescent waves
Group theoretic approaches to nuclear and hadronic collective motion
International Nuclear Information System (INIS)
Biedenharn, L.C.
1982-01-01
Three approaches to nuclear and hadronic collective motion are reviewed, compared and contrasted: the standard symmetry approach as typified by the Interacting Boson Model, the kinematic symmetry group approach of Gell-Mann and Tomonaga, and the recent direct construction by Buck. 50 references
WIX: statistical nuclear multifragmentation with collective expansion and Coulomb forces
Randrup, J.∅rgen
1993-10-01
By suitable augmentation of the event generator FREESCO, a code WIX has been constructed with which it is possible to simulate the statistical multifragmentation of a specified nuclear source, which may be both hollow and deformed, in the presence of a collective expansion and with the interfragment Coulomb forces included.
A microscopic theory of the nuclear collective motion
International Nuclear Information System (INIS)
Baranger, M.
1975-01-01
A microscopic theory of the nuclear collective model is reviewed, discussions being concentrated, mainly, on the shape motion. An adiabatic time dependent Hartree-Fock method is used. Kinetic energy using the cranking model is obtained. The generator coordinate method is discussed [pt
Group theoretic approaches to nuclear and hadronic collective motion
Energy Technology Data Exchange (ETDEWEB)
Biedenharn, L.C.
1982-01-01
Three approaches to nuclear and hadronic collective motion are reviewed, compared and contrasted: the standard symmetry approach as typified by the Interacting Boson Model, the kinematic symmetry group approach of Gell-Mann and Tomonaga, and the recent direct construction by Buck. 50 references.
Energy Technology Data Exchange (ETDEWEB)
Batyrbekov, E.G. [National Nuclear Center of RK, Kurchatov (Kazakhstan); Gordienko, Yu. N., E-mail: gordienko@nnc.kz [National Nuclear Center of RK, Kurchatov (Kazakhstan); Ponkratov, Yu. V. [National Nuclear Center of RK, Kurchatov (Kazakhstan); Khasenov, M.U. [PI “National Laboratory Astana”, Astana (Kazakhstan); Tazhibayeva, I.L.; Barsukov, N.I.; Kulsartov, T.V.; Zaurbekova, Zh. A.; Tulubayev, Ye. Yu.; Skakov, M.K. [National Nuclear Center of RK, Kurchatov (Kazakhstan)
2017-04-15
Highlights: • The development procedure of the ampoule device for experiments with nuclear-excited plasma under neutron irradiation is described. • The methods of nuclear reactions’ energy conversion into the energy of optical radiation of nuclear-excited plasma are presented. • A scheme of reactor experiments, the experimental facility and experimental device to carry out the reactor experiments are considered. - Abstract: This paper describes the development procedure of the reactor ampoule device to perform the experiments on study of spectral luminescence characteristics of nuclear-excited plasma formed by products of {sup 6}Li(n,α){sup 3}H reaction under neutron irradiation at the IVG.1 M research reactor. The methods of nuclear reactions’ energy conversion into the energy of optical radiation of nuclear-excited plasma are presented. A scheme of reactor experiments, the experimental facility and experimental device to carry out the reactor experiments are considered in paper. The designed ampoule device is totally meets the requirements of irradiation experiments on the IVG.1M reactor.
International Nuclear Information System (INIS)
Goree, J.A.; Morfill, G.; Tsytovich, V.N.
1998-01-01
Dust plasma crystals have recently been produced in experiments in a number of laboratories. For dust crystallization to occur, there should exist an efficient mechanism for the cooling of the dust plasma component. It is shown that the excitation of collective plasma modes during collisions between the grains may serve as the required cooling mechanism. The excitation of dust sound waves is found to be most efficient. It is shown that the cooling of dust grains via the excitation of collective plasma modes can be even more efficient than that due to collisions with neutral particles, which was previously considered to be the only mechanism for cooling of the dust plasma component. At present, the first experiments are being carried out to study collisions between individual dust grains. High efficiency of the excitation of plasma modes caused by collisions between dust grains is attributed to the coherent displacement of the plasma particles that shield the grains. it is shown that the excitation efficiency is proportional to the fourth power of the charge of the dust grains and to a large power of their relative velocity, and is independent of their mass. The results obtained can be checked in experiments studying how the binary collisions between dust grains and the pressure of the neutral component influence the dust crystallization
International Nuclear Information System (INIS)
Kitazawa, Masakiyo; Kunihiro, Teiji; Nemoto, Yukio
2007-01-01
Motivated by the observation that there may exist hadronic excitations even in the quark-gluon plasma (QGP) phase, we investigate how the properties of quarks, especially within the quasi-particle picture, are affected by the coupling with bosonic excitations at finite temperature (T), employing Yukawa models with a massive scalar (pseudoscalar) and vector (axial-vector) boson of mass m. The quark spectral function and the quasi-dispersion relations are calculated at one-loop order. We find that there appears at three-peak structure in the quark spectral function with a collective nature when T is comparable with m, irrespective of the type of boson considered. Such a multi-peak structure was first found in a chiral model yielding scalar composite bosons with a decay width. We elucidate the mechanism through which the new quark collective excitations are realized in terms of the Landau damping of a quark (an antiquark) induced by scattering with the thermally excited boson, which gives rise to mixing and hence a level repulsion between a quark (antiquark) and an antiquark-hole (quark-hole) in the thermally excited antiquark (quark) distribution. Our results suggest that the quarks in the QGP phase can be described within an interesting quasi-particle picture with a multi-peak spectral function. Because the models employed here are rather generic, our findings may represent a universal phenomenon for fermions coupled to a massive bosonic excitation with a vanishing or small width. The relevance of these results to other fields of physics, such as neutrino physics, is also briefly discussed. In addition, we describe a new aspect of the plasmino excitation obtained in the hard-thermal loop approximation. (author)
Failure data collection from a Swedish nuclear power plant
International Nuclear Information System (INIS)
Andersson, B.; Bhattacharyya, A.; Hilding, S.
1975-01-01
The Swedish nuclear utilities have formed a joint working group in the field of reliability data of thermal power plants, nuclear and fossil fuelled. The primary task of the working group is to create a standard procedure of collecting failure data from the Swedish nuclear power plants in operation. The failure data will be stored in a joint data bank. A first test collection of such data has been implemented on Oskarshamn I, and the experience with this work is discussed in this report. Reliability analysis of an engineering system is based on the availability of pertinent information on the system components. Right from the beginning within the Swedish nuclear industry the consensus has been that such data can be suitably obtained by monitoring the operating power stations. This has led to a co-operative arrangement between the vendor, ASEA-ATOM and a utility, Oskarshamnsverkets Kraftgrupp AB (OKG) to utilize information from component malfunctions in the reliability analysis. The utility prepares component failure reports which are sent to the vendor for further treatment. Experience gathered to date indicates that this arrangement is effective although many persons are involved in this process of information transmittal. The present set-up is flexible enough to accommodate necessary changes in view of problems which arise now and then in monitoring a complex system like a nuclear power station. This report briefly describes the structure of the failure data collection system. The way in which the raw data collection is done in the station by the owner and the subsequent data processing by the vendor is discussed. A brief status report of the information collected since 1971 is given. It can be concluded that valuable reliability data can be obtained by monitoring component failure reports from an operating power plant. Two requirements are, however, that all the parties involved in the arrangement follow given instructions carefully and that the assumed
Nuclear collectivity and complex alignment mechanisms in light tungsten and osmium nuclei
International Nuclear Information System (INIS)
Johnson, N.R.
1989-01-01
During the past few years there have been significant advances in our understanding of nuclei excited into states of high angular momentum. The development of large multi-detector arrays for γ-γ coincidence spectroscopy studies has propelled the amount of new experimental information available and this has been complemented by notable advances in the theoretical treatments of high-spin phenomena. To provide yet a more detailed understanding of the structure of these high-spin states and to provide a stringent test of these models, we have resorted to measurements of their dynamic electromagnetic multipole moments which are a direct reflection of the collective aspects of the nuclear wave functions. For the most part, these multipole moments are obtained by lifetime measurements utilizing Doppler-shift techniques. Let me stress that the great value of lifetime measurements is that they provide the transition matrix elements without the necessity to rely on nuclear models. 24 refs., 10 figs
Collective doses from airborne discharges by the UK nuclear industry
International Nuclear Information System (INIS)
Kelly, G.N.
1981-01-01
Small quantities of radionuclides are discharged in airborne effluents during the normal operation of nuclear installations. The dispersion of these nuclides in the atmosphere and their subsequent transfer through various sectors of the environment leads to the irradiation of the population. The collective dose to the UK population from airborne discharges in one particular year, 1978, from UK nuclear installations is estimated. The discharges in that year are typical of those in the recent past. Consideration is given to the contribution made by each type of establishment (eg, nuclear power stations, reprocessing plants) and the nuclides which contribute significantly to the collective dose are identified. The distributions of the collective dose in time and among individuals in the exposed population are important features in determining the significance attached to it and both aspects are discussed. The collective dose can be used as a measure of the health detriment associated with the discharge practices considered and is one of several quantities to be taken into account in assessing them. The collective doses from airborne discharges are finally contrasted with those from other sources of exposure of the population. (author)
Electron excitation collision strengths for positive atomic ions: a collection of theoretical data
International Nuclear Information System (INIS)
Merts, A.L.; Mann, J.B.; Robb, W.D.; Magee, N.H. Jr.
1980-03-01
This report contains data on theoretical and experimental cross sections for electron impact excitation of positive atomic ions. It is an updated and corrected version of a preliminary manuscript which was used during an Atomic Data Workshop on Electron Excitation of Ions held at Los Alamos in November 1978. The current status of quantitative knowledge of collisional excitation collision strengths is shown for highly stripped ions where configuration mixing, relativistic and resonance effects may be important. The results show a reasonably satisfactory state for first-row isoelectronic ions and indicate that a considerable amount of work remains to be done for second-row and heavier ions
A seismic analysis of nuclear power plant components subjected to multi-excitations of earthquakes
International Nuclear Information System (INIS)
Ichiki, T.; Matsumoto, T.; Gunyasu, K.
1977-01-01
In this analysis, the modal analysis methods are used to determine the seismic responses of structural systems instead of the direct integration method. These results have been compared with some kinds of other analytical methods, and investigated the accuracy of numerical results of these analysis, applying to such components as Reactor Pressure Vessel and Reactor Internals of an actual plant. The results of this method of analysis are summarized as follows: (1) one of the seismic analysis methods concerning systems subjected to multi-excitations of earthquakes has been presented to the conference of JSME. Although the analytical theory presented to that conference is correct, it has a serious problem about the accuracy of numerical results. This computer program and theory cannot be used practically due to the time necessary to calculate. However, the method described in this paper overcomes those serious problems stated above and has no problem about the computer time and precision. So, it is possible to apply this method to the seismic design of an actual nuclear power plant practically. (2) The feed back effects of the seismic responses of Reactor Internals to Reactor Building are considered so small that we can separate the model of Reactor Internals from Reactor Building. (3) The results of seismic response of Reactor Internals are fairly consistent with those obtained from the model coupled with Reactor Building. (4) This analysis method can be extended to the model of Reactor Internals subjected to more than two random excitations of earthquakes. (5) It is possible that this analysis method is also applied to the seismic analysis of such three-dimensional systems as piping systems subjected to multi-excitations of earthquakes
Gamma-ray induced Doppler broadening and the determination of lifetimes of excited nuclear states
International Nuclear Information System (INIS)
Boerner, H.G.; Jolie, J.; Robinson, S.J.; Kessler, E.G.; Dewey, S.M.; Greene, G.; Deslattes, R.; Ulbig, S.; Lieb, K.P.; Casten, R.F.; Krusche, B.; Cizewski, J.A.
1990-01-01
Measurements of lifetimes of excited states in nuclei yield crucial information for sensitive tests of nuclear models. Here a novel method will be discussed which involves the GRID (Gamma Ray Induced Doppler broadening) technique, in which Doppler broadening is observed in a transition from a nucleus recoiling from the emission of a previous gamma ray. As the recoil energy is extremely small, ultra-high energy resolving power has to be used. To date all such experiments have been carried out at ILL using the GAMS4 double flat crystal spectrometer which is operated in a NIST-ILL collaboration. The method can be used for all lifetimes below a few picoseconds. The wide range of applicability, together with the very exhaustive set of data often obtained, is an advantage with respect to many other methods. The characteristic features of GRID will be discussed using some selected examples. 21 refs., 8 figs
The Mossbauer effect in the 40-sec first-excited nuclear level of 109Ag
International Nuclear Information System (INIS)
Razaie-Serej, S.; Hoy, G.R.
1990-01-01
Narrow spectral lines associated with recoilless nuclear gamma-ray transitions (the Mossbauer effect) are prerequisites for the development of gamma-ray lasers. A successful observation of the Mossbauer effect in the 40-sec., first-excited state of 109 Ag will reveal valuable information on the practical limits of such narrow lines. The authors have used the temperature dependence of the self-absorption of 88-keV gamma rays in a 109 Cd-doped silver single crystal to observe the Mossbauer effect. Their results in the horizontal geometry, in agreement with their previous experiments in the vertical geometry, indicate a 0.2% Mossbauer effect at 4.9 K
International Nuclear Information System (INIS)
Hoffmann, B.
1984-07-01
In three chapters different physical situations are described which have commonly the Coulomb interaction as driving force. The first two chapters study the Coulomb interactions in connection with the excitation of inner electron shells and the Coulomb excitation of nuclei in first order. In the third part on effect ofthe Coulomb interaction between electronic shell and nucleus is treated in second order (nuclear polarization), and its effect on the isotopic and isomeric shift is studied. (orig./HSI) [de
International Nuclear Information System (INIS)
McGowan, F.K.; Stelson, P.H.
1974-01-01
The theory of Coulomb excitation and a brief review of pertinent treatments of the Coulomb excitation process that are useful for the analysis of experiments are given. Examples demonstrating the scope of nuclear structure information obtainable from gamma spectroscopy are presented. Direct Elambda excitation of 232 Th is discussed in terms of the one phonon octupole vibrational spectrum. B(MI) reduced transition probabilities resulting from Coulomb excitation of odd-A deformed nuclei with heavy ions are presented as a test of the rotational model. The use of gamma ray coincidence and particle-gamma coincidence as tools for investigating Coulomb excitation is discussed. (U.S.)
International Nuclear Information System (INIS)
Suzuki, D.; Iwasaki, H.; Ong, H.J.; Imai, N.; Sakurai, H.; Nakao, T.; Aoi, N.; Baba, H.; Bishop, S.; Ichikawa, Y.; Ishihara, M.; Kondo, Y.; Kubo, T.; Kurita, K.; Motobayashi, T.; Nakamura, T.; Okumura, T.; Onishi, T.K.; Ota, S.; Suzuki, M.K.
2008-01-01
Lifetime measurements were performed on low-lying excited states of the neutron-rich isotope 17 C using the recoil shadow method. The γ-decay mean lifetimes were determined to be 583±21(stat)±35(syst) ps for the first excited state at 212 keV and 18.9±0.6(stat)±4.7(syst) ps for the second excited state at 333 keV. Based on a comparison with the empirical upper limits for the electromagnetic transition strengths, these decays are concluded to be predominantly M1 transitions. The reduced M1 transition probabilities to the ground state were deduced to be (1.0±0.1)x10 -2 μ N 2 and (8.2 -1.8 +3.2 )x10 -2 μ N 2 , respectively, for the first and second excited states. The strongly hindered M1 strength as well as the lowered excitation energy represents unique nature of the 212-keV state
Modular sludge collection system for a nuclear steam generator
International Nuclear Information System (INIS)
Appleman, R.H.; Bein, J.D.; Powasaki, F.S.
1986-01-01
A sludge collection system is described for a vertically oriented nuclear steam generator wherein vapors produced in the steam generator pass through means for separating entrained liquid from the vapor prior to the vapor being discharged from the steam generator. The sludge collection system comprises: an upwardly open chamber for collecting the separated liquid and feedwater entering the steam generator; upwardly open sludge collecting containers positioned within the chamber, wherein each of the containers includes a top rim encompassing an opening leading to the interior of each container; generally flat, perforated covers, each of the covers being positioned over one of the openings such that a gap is formed between the cover and the adjacent top rim; sludge agitating means on at least one of the containers; and sludge removal means on at least one of the containers
International Nuclear Information System (INIS)
Sakata, F.; Marumori, T.; Hashimoto, Y.; Tsukuma, H.; Yamamoto, Y.; Terasaki, J.; Iwasawa, Y.; Itabashi, H.
1992-01-01
Since the research field of nuclear physics is expanding rapidly, it is becoming more imperative to develop the microscopie theory of nuclear matter physics which provides us with a unified understanding of diverse phenomena exhibited by nuclei. An estabishment of various stable mean-fields in nuclei allows us to develop the microscopie theory of nuclear collective dynamics within the mean-field approximation. The classical-level theory of nuclear collective dynamics is developed by exploiting the symplectic structure of the timedependent Hartree-Fock (TDHF)-manifold. The importance of exploring the single-particle dynamics, e.g. the level-crossing dynamics in connection with the classical order-to-chaos transition mechanism is pointed out. Since the classical-level theory os directly related to the full quantum mechanical boson expansion theory via the symplectic structure of the TDHF-manifold, the quantum theory of nuclear collective dynamics is developed at the dictation of what os developed on the classical-level theory. The quantum theory thus formulated enables us to introduce the quantum integrability and quantum chaoticity for individual eigenstates. The inter-relationship between the classical-level and quantum theories of nuclear collective dynamics might play a decisive role in developing the quantum theory of many-body problems. (orig.)
Large amplitude nuclear collective motion and the quantized ATDHF theory
International Nuclear Information System (INIS)
Provoost, D.
1986-03-01
It is the aim of the present work to present some numerical results obtained within the ATDHF formalism. Both approaches have been considered, the construction of the collective Hamiltonian as well as the solution of the Griffin-Hill-Wheeler equation, both using the ATDHF collective path. We show that a fully selfconsistent microscopic description of nuclear phemomena using general many-body techniques can be treated on the numerical level. We considered several different systems to indicate as much as possible the present possibilities and limits of the theory as well as of the numerical techniques. (orig./HSI)
Nuclear structure studies by means of magnetic moments of excited states
International Nuclear Information System (INIS)
Kaeubler, L.; Prade, H.; Schneider, L.; Brinckmann, H.F.; Stary, F.
1981-09-01
Experimental arrangements installed at the cyclotron U-120 and the tandem accelerator EGP-10 for the in-beam measurement of magnetic moments of excited nuclear states are discribed. The Perturbed-Angular-Distribution-method (PAD) has been used. A new evaluation method has been developed for the unique determination of the Larmor frequency from spin-procession spectra R(t) with less than half of an oscillation period between consecutive particle pulses. Magnetic moments in transitional nuclei or in nuclei near closed shells ( 103 Pd, 105 Ag, 117 Sb, 117 Te, 121 Te, 121 I, 143 Pm and 207 Bi) were measured. The results are discussed with the aim to get information about the nuclear structure of the corresponding isomeric states in connection with complex spectroscopic investigations. Therefore, the experimental values are compared to the results of model calculations (core-polarization, core-particle-coupling, Nilsson, particle-rotation-coupling or shell-model) or to the estimates on the basis of the additivity of effective magnetic moments. Single-particle aspects are discussed in connection with the magnetic moments of hsub(11/2)-, dsub(5/2)- and gsub(7/2)-neutron (ν) and proton (π) states in the nuclei 103 Pd, 117 Te, 121 Te and 143 Pm, respectively. The configurations of (π) 3 and (π)(ν) 2 -three-particle states in 105 Ag, 117 Sb, 121 I and 207 Bi could be determined using the additivity rule. The experimental magnetic moments of states in 143 Pm agree very well with the results of shell-model calculations, which have firstly been carried out also for negative-parity states in this mass region. Considering magnetic moments in 117 Te and 121 Te we could demonstrate the influence of different nuclear deformations on the magnetic moments in transitional nuclei. (author)
New limits for the 2 νββ decay of 96Zr to excited nuclear states of 96Mo
Finch, Sean; Tornow, Werner
2015-10-01
The final results from our search for the 2 νββ decay of 96Zr to excited 0+ and 2+ states of 96Mo are presented. Such measurements provide valuable test cases for 2 νββ -decay nuclear matrix element calculations, which in turn are used to tune 0 νββ -decay nuclear matrix element calculations. After undergoing double- β decay to an excited state, the excited daughter nucleus decays to the ground state, emitting two coincident γ rays. These two γ rays are detected in coincidence by two HPGe detectors sandwiching the 96Zr sample, with a NaI veto in anti-coincidence. This experimental apparatus, located at the Kimballton Underground Research Facility (KURF), has previously measured the 2 νββ decay of 100Mo and 150Nd to excited nuclear states. Experimental limits on the T1 / 2 and corresponding nuclear matrix element are presented for each of these decays. As a byproduct of this experiment, limits were also set on the single- β decay of 96Zr. Supported by DOE Grant: DE-FG02-97ER41033.
Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation
Reiter, P; Blazhev, A A; Voulot, D; Meot, V H; Simpson, G S; Georgiev, G P; Gaudefroy, L; Roig, O
We propose to study the properties of odd-mass neutron-rich rubidium isotopes by the Coulomb-excitation technique, using the Miniball array coupled to the REX-ISOLDE facility. The results from similar measurements from the recent years (e.g. for the odd-mass and the odd-odd Cu isotopes, IS435) have shown the strong potential in such measurements for gaining information both for single-particle-like and collective states in exotic nuclei. Since there is practically no experimental information for excited states in the odd-mass Rb isotopes beyond $^{93}$Rb, the present study should be able to provide new data in a region of spherical ($^{93}$Rb and $^{95}$Rb) as well as well-deformed nuclei ($^{97}$Rb and $^{99}$Rb). Of particular interest is the rapid shape change that occurs when going from $^{95}$Rb (${\\varepsilon}_{2}$=0.06) to $^{97}$Rb (${\\varepsilon}_{2}$=0.3). These results should be of significant astrophysical interest as well, due to the close proximity of the r-process path.
International Nuclear Information System (INIS)
Bar'yakhtar, V.G.; Belykh, V.G.; Soboleva, T.K.
1989-01-01
In the framework of the general hydrodynamic approach a method is proposed for describing the relaxation of low-frequency magnetic excitations in disordered spin systems and many-sublattice magnets. Expressions are obtained in terms of Goldstone fields for the dissipation function both in the exchange approximation and when allowance is made for relativistic interactions
Selected topics in nuclear structure
International Nuclear Information System (INIS)
1994-01-01
The collection of abstracts on selected topics in nuclear structure are given. Special attention pays to collective excitations and high-spin states of nuclei, giant resonance structure, nuclear reaction mechanisms and so on
Perspectives in the theory of nuclear collective motion
International Nuclear Information System (INIS)
Klein, A.
1980-01-01
This report discusses three different subjects. The first is the development of a generalized version of the VMI (variable moment of inertia) model that ties it to the original form of the IBM (interacting boson model) and provides a possibility of fitting vibrational spectra with generalized vibrational formulas. The second is a suggestion for fitting band crossing calculations of the phenomenological type more completely than has hitherto been done into the framework of the VMI method. The third, which is the most important and far reaching, is the description f a complete mathematical method for the microscopic derivation of the IBM from a conventional shell-model Hamiltonian. In addition to elements already foreseen by previous authors, there is proposed a solution for the most important problem outstanding, not only within the framework of the IBM, but also in all previous work on boson expansion. This is the problem of actually selecting, in a general fashion, the most collective excitations. A criterion is introduced that the subspace constructed from these excitations should possess an average energy that is lower than the rest of the shell model space; the actual implementation of this criterion is explained. 8 tables, 62 references
Master equations in the microscopic theory of nuclear collective dynamics
International Nuclear Information System (INIS)
Matsuo, M.; Sakata, F.; Marumori, T.; Zhuo, Y.
1988-07-01
In the first half of this paper, the authors describe briefly a recent theoretical approach where the mechanism of the large-amplitude dissipative collective motions can be investigated on the basis of the microscopic theory of nuclear collective dynamics. Namely, we derive the general coupled master equations which can disclose, in the framework of the TDHF theory, not only non-linear dynamics among the collective and the single-particle modes of motion but also microscopic dynamics responsible for the dissipative processes. In the latter half, the authors investigate, without relying on any statistical hypothesis, one possible microscopic origin which leads us to the transport equation of the Fokker-Planck type so that usefullness of the general framework is demonstrated. (author)
Energy Technology Data Exchange (ETDEWEB)
Hirano, Masashi [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)
1997-07-01
This paper describes the results of a scoping study on seismically induced resonance of nuclear-coupled thermal-hydraulic instability in BWRs, which was conducted by using TRAC-BF1 within a framework of a point kinetics model. As a result of the analysis, it is shown that a reactivity insertion could occur accompanied by in-surge of coolant into the core resulted from the excitation of the nuclear-coupled instability by the external acceleration. In order to analyze this phenomenon more in detail, it is necessary to couple a thermal-hydraulic code with a three-dimensional nuclear kinetics code.
Onset of collectivity in $^{96,98}$Sr studied via Coulomb excitation
Clement, E; Dijon, A; de France, G; Bastin, B; Blazhev, A; Bree, N; Butler, P; Delahaye, P; Ekstrom, A; Georgiev, G; Hasan, N; Iwanicki, J; Jenkins, D; Korten, W; Larsen, A C; Ljungvall, J; Moschner, K; Napiorkowski, P; Pakarinen, J; Petts, A; Renstrom, T; Seidlitz, M; Siem, S; Sotty, C; Srebrny, J; Stefanescu, I; Tveten, G M; Van de Walle, J; Warr, N; Wrzosek-Lipska, K; Zielinska, M; Bauer, C; Bruyneel, B; Butterworth, J; Fitzpatrick, C; Fransen, C; GernhäUser, R; Hess, H; Lutter, R; Marley, P; Reiter, P; Siebeck, B; Vermeulen, M; Wiens, A; De Witte, H
2014-01-01
A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N=60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.
Onset of collectivity in 96,98Sr studied via Coulomb excitation
Directory of Open Access Journals (Sweden)
Clément E.
2014-03-01
Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N=60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.
Nuclear collective rotation in the SU3 model, 2
International Nuclear Information System (INIS)
Kinouchi, Shin-ichi; Kishimoto, Teruo; Kammuri, Tetsuo.
1989-05-01
The collective rotation of a nuclear system with the SU 3 Hamiltonian is described by the quantal dynamical nuclear field theory. An angular frequency in the Coriolis interaction of the driving Hamiltonian is replaced by a total angular momentum operator divided by the corresponding moment of inertia. We consider here the low spin states for a triaxial intrinsic configuration. The rotational effect is taken into account by using the effective quadrupole and angular momentum operators, whose expressions are different depending on whether they refer to the laboratory frame or the body-fixed one. Effective forms of the total Hamiltonian and the particle angular momentum are compared with the exact SU 3 energy and the rotor's angular momentum, respectively. In order to dissolve the disagreement for the effective operators, the perturbing interaction should be supplemented by a residual part of the quadrupole-quadrupole interaction, which restores the rotational invariance of the intrinsic Hamiltonian. (author)
Operational data collection and analysis for nuclear plant life extension
International Nuclear Information System (INIS)
DuCharme, A.R.; Berg, R.M.; Bailey, T.L.
1989-01-01
This paper describes initial work undertaken by the US Department of Energy, through Sandia National Laboratories in Albuquerque, New Mexico, to define the operational data necessary for support of nuclear plant life extension (PLEX) programs. This work is being performed in coordination with the Working Group on Plant Life Extension of the US Nuclear Management and Resources Council. The intent of the effort is to use results gained initially from pilot PLEX programs a US BWR and a US PWR to build towards the use of ''PLEX indicators'' by which a plant's readiness for successful life extension can be measured. Another objective of the study was to examine chemistry data in detail to determine how well US plants are collecting, preserving, and trending the chemistry data that is important to PLEX. The methods used to disseminate this data to outside agencies and other utilities were studied. Finally, an analysis was made to determine additional chemistry data needed to support PLEX
International Nuclear Information System (INIS)
Basharov, A.M.
2011-01-01
New effects of suppression of the collective spontaneous emission and superradiance have been predicted. At a certain number N of ensemble atoms, the Stark interaction with a vacuum field was shown as being high enough for the excited N-atom ensemble to be stabilized with respect to the collective decay. The result was derived analytically as a consequence of applying the quantum stochastic differential equations to the description of the atomic dynamics in vacuum, where the Stark interaction operator is expressed in terms of the quantum Poisson process. -- Highlights: → Enhancement of the Stark interaction of N atoms ensemble with vacuum, with N rising. → Representation of the Stark interaction as the quantum Poisson process. → Collective spontaneous decay and superradiance under the strong Stark interaction. → Inhibition of superradiance at a certain number of ensemble atoms. → Analysis of superradiance experiments in terms of inhibition of collective decay.
Nuclear excitations and reaction mechanisms. Report of progress, February 1, 1975--October 31, 1975
International Nuclear Information System (INIS)
1975-01-01
Progress in the following areas of research is reported: Energies of giant isoscalar monopole and quadrupole excitations, energy-weighted sum rules, the random-phase approximation, Hartree-Fock calculations, spreading widths, physical consequences of the locality of current-density commutators and current-current sum rules. Electron-hydrogen scattering using the inhomogenous equation method; variational calculation of e - + H scattering using the symmetrized channel coupling array equation; K operators and unitary approximations for the 3-body problem; approximate calculation of model (d-p) and (dd) amplitudes and cross sections; multi-step processes in direct reactions; bound state calculations using the channel coupling array theory. Methods for determining nuclear charge distributions, relativistic effects in nuclei, dispersion corrections and recoil corrections to elastic electron scattering; unitarity of elastic scattering amplitudes; low energy theorems for two-photon processes; pion-exchange contributions to the charge density; recoil effects and energy-dependent Hamiltonians; pion-exchange contributions to two-photon processes; hypervirial theorems for the Dirac equation; Coulomb energies of nuclei. Pion-nucleus scattering, diagonalization of the Δ-(nucleon-hole) configurations, doorway states and doorway dominance, calculations for 4 He, discussion of experimental results
The surrogate-reaction method and excitation-energy sorting in nuclear fission
International Nuclear Information System (INIS)
Jurado, Beatriz
2015-01-01
This manuscript summarises the main activities that I have carried out during the last ten years of research at the Centre d'etudes Nucleaires de Bordeaux-Gradignan (CENBG). It is, to a great extent, a synthesis of nine articles. They can be consulted by the reader that would like to have more detailed information. These articles are denoted as Article I, II.. all along the manuscript. The manuscript is intended to be accessible to PhD students not familiar with the topic. Chapter 1 recalls some of the basic ideas of statistical mechanics and discusses the applicability of its concepts to nuclei. Some of these concepts, in particular the concept of statistical equilibrium, are essential for the topics covered by chapters 2 and 3. Chapter 2 summarises the studies performed by the CENBG collaboration on the surrogate-reaction method in the last ten years. Chapter 3 summarises part of the work done on the modelling of nuclear fission in collaboration with Karl-Heinz Schmidt, it considers the partition of excitation energy and unpaired nucleons in fission on the basis of statistical mechanics. Chapters 2 and 3 contain the bulk of my work, each of them has its own introduction and conclusion sections. Chapter 4 presents the medium and long-term experimental perspectives for the topics described in chapters 2 and 3. (author)
Boson mapping and the microscopic collective nuclear Hamiltonian
International Nuclear Information System (INIS)
Dobes, J.; Ivanova, S.P.; Dzholos, R.V.; Pedrosa, R.
1990-01-01
Starting with the mapping of the quadrupole collective states in the fermion space onto the boson space, the fermion nuclear problem is transformed into the boson one. The boson images of the bifermion operators and of the fermion Hamiltonian are found. Recurrence relations are used to obtain approximately the norm matrix which appears in the boson-fermion mapping. The resulting boson Hamiltonian contains terms which go beyond the ordinary SU(6) symmetry Hamiltonian of the interacting boson model. Calculations, however, suggest that on the phenomenological level the differences between the mapped Hamiltonian and the SU(6) Hamiltonian are not too important. 18 refs.; 2 figs
The residual proton-neutron interaction and nuclear collectivity
International Nuclear Information System (INIS)
Casten, R.F.
1990-01-01
The essential role of the valence, residual p-n interaction in the development of collectivity, though long known in general terms, has recently become increasingly apparent. A brief review of the p-n interaction is given, including some very basic nuclear data that illustrate its effects and the phenomenological N p N n scheme and the P-factor. This is followed by a discussion of recent experimental extractions of p-n matrix elements throughout the periodic table and theoretical efforts to understand them, in terms of both Shell and Nilsson models. 20 refs., 13 figs
Nuclear collective flow from gaussian fits to triple differential distributions
International Nuclear Information System (INIS)
Gosset, J.; Demoulins, M.; Babinet, R.; Cavata, C.; Fanet, H.; L'Hote, D.; Lucas, B.; Poitou, J.; Valette, O.; Alard, J.P.; Augerat, J.; Bastid, N.; Charmensat, P.; Dupieux, P.; Fraysse, L.; Marroncle, J.; Montarou, G.; Parizet, M.J.; Qassoud, D.; Rahmani, A.; Brochard, F.; Gorodetzky, P.; Racca, C.
1990-01-01
In order to study the nuclear collective flow, the triple differential momentum distributions of charged baryons are fitted to a simple anisotropic gaussian distribution, within an acceptance which removes most of the spectator contribution. The adjusted flow angle and aspect ratios are corrected for systematic errors in the determination of the reaction plane. This method has been tested with Monte Carlo simulations and applied to experimental results and intranuclear cascade simulations of argon-nucleus collisions at 400 MeV per nucleon. (orig.)
Crossed-coil detection of two-photon excited nuclear quadrupole resonance
Eles, Philip T.; Michal, Carl A.
2005-08-01
Applying a recently developed theoretical framework for determining two-photon excitation Hamiltonians using average Hamiltonian theory, we calculate the excitation produced by half-resonant irradiation of the pure quadrupole resonance of a spin-3/2 system. This formalism provides expressions for the single-quantum and double-quantum nutation frequencies as well as the Bloch-Siegert shift. The dependence of the excitation strength on RF field orientation and the appearance of the free-induction signal along an axis perpendicular to the excitation field provide an unmistakable signature of two-photon excitation. We demonstrate single- and double-quantum excitation in an axially symmetric system using 35Cl in a single crystal of potassium chlorate ( ωQ = 28 MHz) with crossed-coil detection. A rotation plot verifies the orientation dependence of the two-photon excitation, and double-quantum coherences are observed directly with the application of a static external magnetic field.
Collecting and recirculating condensate in a nuclear reactor containment
International Nuclear Information System (INIS)
Schultz, T.L.
1993-01-01
An arrangement passively cools a nuclear reactor in the event of an emergency, condensing and recycling vaporized cooling water. The reactor is surrounded by a containment structure and has a storage tank for cooling liquid, such as water, vented to the containment structure by a port. The storage tank preferably is located inside the containment structure and is thermally coupleable to the reactor, e.g. by a heat exchanger, such that water in the storage tank is boiled off to carry away heat energy. The water is released as a vapor (steam) and condenses on the cooler interior surfaces of the containment structure. The condensed water flows downwardly due to gravity and is collected and routed back to the storage tank. One or more gutters are disposed along the interior wall of the containment structure for collecting the condensate from the wall. Piping is provided for communicating the condensate from the gutters to the storage tank. 3 figures
Collecting and recirculating condensate in a nuclear reactor containment
Schultz, Terry L.
1993-01-01
An arrangement passively cools a nuclear reactor in the event of an emergency, condensing and recycling vaporized cooling water. The reactor is surrounded by a containment structure and has a storage tank for cooling liquid, such as water, vented to the containment structure by a port. The storage tank preferably is located inside the containment structure and is thermally coupleable to the reactor, e.g. by a heat exchanger, such that water in the storage tank is boiled off to carry away heat energy. The water is released as a vapor (steam) and condenses on the cooler interior surfaces of the containment structure. The condensed water flows downwardly due to gravity and is collected and routed back to the storage tank. One or more gutters are disposed along the interior wall of the containment structure for collecting the condensate from the wall. Piping is provided for communicating the condensate from the gutters to the storage tank.
Collective excitations in neutron-rich nuclei within the model of a Fermi liquid drop
International Nuclear Information System (INIS)
Kolomietz, V.M.; Magner, A.G.
2000-01-01
We discuss a new mechanism of splitting of giant multipole resonances (GMR) in spherical neutron-rich nuclei. This mechanism is associated with the basic properties of an asymmetric drop of nuclear Fermi liquid. In addition to well-known isospin shell-model predictions, our approach can be used to describe the GMR splitting phenomenon in the wide nuclear-mass region A ∼ 40-240. For the dipole isovector modes, the splitting energy, the relative strength of resonance peaks, and the contribution to the energy-weighted sum rules are in agreement with experimental data for the integrated cross sections for photonuclear (γ, n) and (γ, p) reactions
Nuclear power and the public: an update of collected survey research on nuclear power
International Nuclear Information System (INIS)
Rankin, W.L.; Melber, B.D.; Overcast, T.D.; Nealey, S.M.
1981-12-01
The purpose of this research was to collect, analyze, and summarize all of the nuclear power-related surveys conducted in the United States through June 1981, that we could obtain. The surveys collected were national, statewide, and areawide in scope. Slightly over 100 surveys were collected for an earlier, similar effort carried out in 1977. About 130 new surveys were added to the earlier survey data. Thus, about 230 surveys were screened for inclusion in this report. Because of space limitations, national surveys were used most frequently in this report, followed distantly by state surveys. In drawing our conclusions about public beliefs and attitudes toward nuclear power, we placed most of our confidence in survey questions that were used by national polling firms at several points in time. A summary of the research findings is presented, beginning with general attitudes toward nuclear power, followed by a summary of beliefs and attitudes about nuclear power issues, and ended by a summary of beliefs and attitudes regarding more general energy issues
Nuclear power and the public: an update of collected survey research on nuclear power
Energy Technology Data Exchange (ETDEWEB)
Rankin, W.L.; Melber, B.D.; Overcast, T.D.; Nealey, S.M.
1981-12-01
The purpose of this research was to collect, analyze, and summarize all of the nuclear power-related surveys conducted in the United States through June 1981, that we could obtain. The surveys collected were national, statewide, and areawide in scope. Slightly over 100 surveys were collected for an earlier, similar effort carried out in 1977. About 130 new surveys were added to the earlier survey data. Thus, about 230 surveys were screened for inclusion in this report. Because of space limitations, national surveys were used most frequently in this report, followed distantly by state surveys. In drawing our conclusions about public beliefs and attitudes toward nuclear power, we placed most of our confidence in survey questions that were used by national polling firms at several points in time. A summary of the research findings is presented, beginning with general attitudes toward nuclear power, followed by a summary of beliefs and attitudes about nuclear power issues, and ended by a summary of beliefs and attitudes regarding more general energy issues.
Analysis and treatment of diametral tolerance of exciter shaft of the 650 MW nuclear power plant
International Nuclear Information System (INIS)
Liu Qiang
2010-01-01
The generator and exciter has three support connection in Qinshan II, i.e. there are two bearings for the generator rotor and one for the exciter. This structure results in difficulty to meet the standard when checking the exciter bearing's diametral tolerance. In the fifth outage of unit 2 turbo-generator in Qinshan II, the diametral tolerance failed to meet the standard. There were several reasons, such as the alignment of generator and exciter coupling, the angular moment of generator and exciter coupling bolt, the end surface condition of generator and exciter coupling, the fitting dimension of the coupling bolt hole and the sleeve in it. After analysis and screening of all factors, it was confirmed that the radical reason was the abnormal condition of the generator coupling end surface, and the problem was solved by machining the end surface. (author)
Nuclei far from stability. Individual and collective excitations at low energy
International Nuclear Information System (INIS)
Meyer, M.
1984-01-01
The low energy structure of exotic nuclei is discussed in terms of self-consistent microscopic models. The experimental striking features of the spectroscopy of these nuclei are briefly surveyed and the schematic steps performed to obtain from effective N-N interactions their spectroscopic properties are presented. Their saturation and deformation properties are given by the Hartree-Fock approximation (HF). Then it is shown how to describe the dynamics of even-even exotic nuclei excited states by solving the complete Bohr Hamiltonian, built microscopically using the HF approximation and the adiabatic limit (and its derivatives) of the time-dependent HF approximation (ATDHF). The structure of odd and doubly odd nuclei is discussed in the framework of the unified model, ie the microscopic rotor + quasiparticles model. Finally possible future directions of experimental research concerning exotic nuclei are described and improvements or new theoretical approaches discussed [fr
Chiral approach to nuclear matter: Role of two-pion exchange with virtual delta-isobar excitation
Fritsch, S.; Kaiser, N.; Weise, W.
2004-01-01
We extend a recent three-loop calculation of nuclear matter in chiral perturbation theory by including the effects from two-pion exchange with single and double virtual $\\Delta(1232)$-isobar excitation. Regularization dependent short-range contributions from pion-loops are encoded in a few NN-contact coupling constants. The empirical saturation point of isospin-symmetric nuclear matter, $\\bar E_0 = -16 $MeV, $\\rho_0 = 0.16 $fm$^{-3}$, can be well reproduced by adjusting the strength of a two-...
International Nuclear Information System (INIS)
Gareev, F.A.; Zhidkova, I.E.; Ratis, Yu.L.
2004-01-01
We have concluded that cold transmutation of nuclei is possible in the framework of the modern physical theory - excitation and ionization of atoms and the universal resonance synchronization principle are responsible for it. Investigation of this phenomenon requires knowledge of different branches of 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. (author)
Cold or hot, stable or unstable collective nuclear motion
International Nuclear Information System (INIS)
Chomaz, Ph.; Lacroix, D.; Jacquot, B.; Colonna, M.; Ayik, S.
1999-01-01
We present a general discussion of the mean field dynamics of finite nuclei prepared under extreme of temperature and pressure. Many features of the dynamics are carefully studied such as the collective expansion, the evaporation process, the different time-scale. We show that under the thermal pressure and the effect of the compression, the system may reach low density regions where it may become unstable. Early development of the instabilities in a dilute nuclear source in investigated using a finite temperature quantal Rpa approach for different systems. The growth rates of the unstable collective modes are determining by solving a dispersion relation. Which is obtained by parameterizing the transition density in terms of its multipole moments. Under typical conditions of a dilute finite system at moderate temperatures the dispersion relation exhibits an ultraviolet cut-off. As a result, only a finite number of multiple modes becomes unstable , and the number of the unstable collective modes increases with the size of the source. Calculations indicate that for an expanding source, unstable modes show a transition from surface to volume character. (author)
Technique for description of nonrotational excited states in a semiphenomenological nuclear theory
International Nuclear Information System (INIS)
Krutov, V.A.
1985-01-01
A non-standard technique for microscopic description of excited nonrotational states is considered; it is suitable for inseparable force application. Besides, an additional binding operator, mixing quasi-particle excitations and E1-resonance states, is considered. Instead of the standard technique of state ''collectivization'' of the random phase approximation type it is used the so-called ''method of bound amplitudes''
International Nuclear Information System (INIS)
Kumar, D.; Barman, A.; Kłos, J. W.; Krawczyk, M.
2014-01-01
We present the observation of a complete bandgap and collective spin wave excitation in two-dimensional magnonic crystals comprised of arrays of nanoscale antidots and nanodots, respectively. Considering that the frequencies dealt with here fall in the microwave band, these findings can be used for the development of suitable magnonic metamaterials and spin wave based signal processing. We also present the application of a numerical procedure, to compute the dispersion relations of spin waves for any high symmetry direction in the first Brillouin zone. The results obtained from this procedure have been reproduced and verified by the well established plane wave method for an antidot lattice, when magnetization dynamics at antidot boundaries are pinned. The micromagnetic simulation based method can also be used to obtain iso–frequency contours of spin waves. Iso–frequency contours are analogous of the Fermi surfaces and hence, they have the potential to radicalize our understanding of spin wave dynamics. The physical origin of bands, partial and full magnonic bandgaps have been explained by plotting the spatial distribution of spin wave energy spectral density. Although, unfettered by rigid assumptions and approximations, which afflict most analytical methods used in the study of spin wave dynamics, micromagnetic simulations tend to be computationally demanding. Thus, the observation of collective spin wave excitation in the case of nanodot arrays, which can obviate the need to perform simulations, may also prove to be valuable
Collection and treatment of reliability data for nuclear plants
International Nuclear Information System (INIS)
McHugh, B.
1973-09-01
This paper describes some of the results achieved with the Argus data bank at the Institution of Thermal Power Engineering at the Chalmers University of Technology. This data bank, or rather data collection system, has been established to cover nuclear activities the world over. The system comprises in essence a number of data files. The prime files are those containing the basic data on the various plants - plant size and type, country and NSSS supplier and an indication of plantstatus. Further files contain plant design data and parameters and all available information on construction as commissioning timetables. To cover the operation of plant two files have been established. One file, which is updated on a monthly basis, contains power production statistics. The other file contains failure data. In this file are recorded the time and duration of plant shutdown together with the primary reason (s) for this. (M.S.)
Nuclear collective flow from gaussian fits to triple differential distributions
International Nuclear Information System (INIS)
Gosset, J.; Babinet, R.; Cavata, C.; Marco, M. de; Demoulins, M.; Fanet, H.; Fodor, Z.; L'Hote, D.; Lucas, B.
1990-01-01
A simple characterization of triple differential cross sections is needed for a systematic study of the nuclear matter collective flow in relativistic nucleus-nucleus collisions. Our analysis is based upon a fitting procedure, so that the triple differential distributions need not be measured in the whole momentum space. If the detector acceptance eliminates most spectator particles or if it is artificially restricted for doing so, this method leads to a flow characterization of the participant nuclear matter. The center-of-mass triple-differential momentum distributions are fitted to a simple analytical shape, namely an anisotropic Gaussian distribution. The adjusted parameters (flow angle and aspect ratios) are corrected for uncertainty in the event-by-event determination of the reaction plane azimuth (finite-number effects). Results are presented for neon-nucleus and argon-nucleus collisions at incident energy between 400 and 800 MeV per nucleon. Flow is already significant for light systems, and depends clearly upon the impact parameter
Selected topics in the quantum theory of solids: collective excitations and linear response
International Nuclear Information System (INIS)
Balakrishnan, V.
1977-08-01
This report is based on the lecture notes of a course given at the Department of Physics, Indian Institute of Technology, Madras, during the period January-April 1976 for M.Sc. students. The emphasis is on the concept of elementary excitations in many-body systems, and on the technique of linear response theory. Various topics are covered in 7 sections. The second section following the introductory section is on 'second quantization' and includes discussion on creation and destruction operators, multiparticle states, time-dependent operators etc. Section 3 deals with the 'electron gas' and includes discussion on non-interacting Fermi gas, Coulomb interaction and exchange energy, the two-electron correlation function etc. Section 4 deals with the dielectric response analysis of the electron gas and includes discussion on Coulomb interaction in terms of density fluctuations, self-consistent field dielectric function etc. In section 5 the 'linear response theory' is explained. The Liouville operator, Boltzmann's superposition integral, dispersion relations etc. are explained. Quasiparticles and plasmous are discussed in the Section 6. Section 7 deals with 'lattice dynamics and phonons'. In the last section 8, spin waves are explained. The Heisenberg exchange hamiltonian, Green Function for noninteracting magnons etc. are discussed. (author)
Nsub(4,5) excitations in metallic cesium: single electron behaviour and collective effects
International Nuclear Information System (INIS)
Petersen, H.
1975-07-01
The Nsub(4,5) excitation spectrum of Cs was measured with yield spectroscopy from the onset of transitions at 77 eV to 180 eV photon energy. Synchrotron radiation served as a light source. A broad maximum due to delayed transitions to f-symmetric continuum states is the dominating feature of the spectrum. An indication for existence of localized f-symmetric final states is found. Above the Nsub(4,5) edges at 77.1 +- 0.1 eV and 79.3 +- 0.1 eV photon energy transitions to p-symmetric extended metal states are observed. Their qualitative agreement with APW band structure calculations is discussed. EDC's obtained with photon energies 75 and 111 eV are presented. The observed asymmetric shape of the 4d photoemission maxima in the EDC's and the shape of the N 5 edge are discussed with regard to the final state interaction theory by Mahan, Nozieres and de Dominicis. (orig.) [de
Kinetic theory of collective excitations and damping in Bose-Einstein condensed gases
Al Khawaja, U.; Stoof, H.T.C.
2000-01-01
We calculate the frequencies and damping rates of the low-lying collective modes of a Bose-Einstein condensed gas at nonzero temperature. We use a complex nonlinear Schrödinger equation to determine the dynamics of the condensate atoms, and couple it to a Boltzmann equation for the noncondensate
International Nuclear Information System (INIS)
Bell, H.G.
1976-07-01
The energy spectra of Ne studied under different temperatures and pressures with the aid of inelastic, coherent neutron scattering can be described by a scattering law derived from the basic hydrodynamic equations. The Brillouin lines found with very small momentum transfer 0.06 A -1 -1 are interpreted as collective, adiabatic pressure fluctuations. (orig./WL) [de
Collective excitations with chiral NN+3N interactions from coupled-cluster and in-medium SRG
International Nuclear Information System (INIS)
Trippel, Richard
2016-01-01
A broad variety of many-body methods exists for the investigation of ground-state properties, ranging from sophisticated ab initio approaches to traditional, phenomenological models. The description of low-lying excited states of medium-mass nuclei with ab initio methods has also become possible through recent progress in many-body theory. For collective modes at higher energies, however, these methods usually cannot be applied. Therefore, when describing collective excitations either completely phenomenological, macroscopic models are employed or microscopic models using phenomenological interactions. One of the microscopic models well suited for the calculation of collective properties is the random-phase approximation (RPA). In the past, the use of phenomenological interactions for RPA has shown promising results. However, the application of chiral NN interactions yielded transitions at significantly too high energies, far from agreement with experimental data. This thesis focuses on the description of collective modes using both RPA and its second-order extension, SRPA. In contrast to previous research endeavors, we employ chiral NN+3N interactions. The use of chiral interactions is an important first step for describing ground-state, excitation and collective properties on an equal foundation. We find that the inclusion of 3N terms is crucial for RPA calculations and the prediction for collective modes is drastically improved through the 3N terms. For SRPA we show first-ever results with chiral interactions, again leading to an improvement in the predictions. For a successful ab initio description of ground-state properties the inclusion of correlations is of paramount importance. Past RPA calculations have been performed using the quasi-boson approximation, effectively neglecting ground-state correlations. Using RPA, the next step along the path towards an ab initio description of collective properties will, therefore, be the inclusion of correlations. To
Collective excitations with chiral NN+3N interactions from coupled-cluster and in-medium SRG
Energy Technology Data Exchange (ETDEWEB)
Trippel, Richard
2016-12-19
A broad variety of many-body methods exists for the investigation of ground-state properties, ranging from sophisticated ab initio approaches to traditional, phenomenological models. The description of low-lying excited states of medium-mass nuclei with ab initio methods has also become possible through recent progress in many-body theory. For collective modes at higher energies, however, these methods usually cannot be applied. Therefore, when describing collective excitations either completely phenomenological, macroscopic models are employed or microscopic models using phenomenological interactions. One of the microscopic models well suited for the calculation of collective properties is the random-phase approximation (RPA). In the past, the use of phenomenological interactions for RPA has shown promising results. However, the application of chiral NN interactions yielded transitions at significantly too high energies, far from agreement with experimental data. This thesis focuses on the description of collective modes using both RPA and its second-order extension, SRPA. In contrast to previous research endeavors, we employ chiral NN+3N interactions. The use of chiral interactions is an important first step for describing ground-state, excitation and collective properties on an equal foundation. We find that the inclusion of 3N terms is crucial for RPA calculations and the prediction for collective modes is drastically improved through the 3N terms. For SRPA we show first-ever results with chiral interactions, again leading to an improvement in the predictions. For a successful ab initio description of ground-state properties the inclusion of correlations is of paramount importance. Past RPA calculations have been performed using the quasi-boson approximation, effectively neglecting ground-state correlations. Using RPA, the next step along the path towards an ab initio description of collective properties will, therefore, be the inclusion of correlations. To
Large amplitude nuclear collective motion and the quantized ATDHF theory
International Nuclear Information System (INIS)
Provoost, D.
1986-01-01
Several nuclear systems are studied within the quantized ATDHF theory. For the α- 16 O system, after construction of the wave functions along the collective path, a collective Schroedinger equation, including quantum corrections, is derived in the Gaussian Overlap Approximation and solved for scattering and bound states. The elastic scattering cross sections agree well with experiment at low energies. An alternative possibility is to perform angular momentum projections on the wave functions and to insert the Hamilton- and normkernels in the Griffin-Hill-Wheeler equation. The widths of the resonances are extracted from the poles of the S-matrix in the complex energy plane. Good agreement is obtained for the energies of even-parity levels but the odd-parity levels are shifted in energy as compared with experiment. The origin of this discrepancy is to be found in the BKN interaction which is not able to reproduce the binding energies of α, 16 O and 20 Ne. For the α- 12 C system, with a deformed fragment, the agreement with experiment is poor. One difficulty is the problem of how to link the different paths of the different configurations which are possible for the α- 12 C system. All calculations have been performed on a three-dimensional lattice. (MCB)
Recent advances in the physics of collective excitations in the Paul trap simulator experiment
International Nuclear Information System (INIS)
Gilson, E.P.; Chung, M.; Davidson, R.C.; Dorf, M.; Efthimion, P.C.; Godbehere, A.B.; Majeski, R.
2009-01-01
The Paul trap simulator experiment (PTSX) is a compact laboratory linear Paul trap that simulates the transverse dynamics of a long charged-particle bunch propagating through a magnetic alternating-gradient (AG) transport system. The transverse dynamics of particles in the AG system in the beam's frame-of-reference and those of particles in PTSX are described by the same sets of equations, including all nonlinear space-charge effects. Initial experimental results are presented in which the collective transverse symmetric mode (m=0) and quadrupole mode (m=2) have been observed in pure-barium-ion plasmas in PTSX, with a depressed-tune ν/ν 0 ∼0.9, with the intent of identifying collective modes whose signature will serve as a robust diagnostic for key properties of the beam, such as line density and transverse emittance. The results of particle-in-cell simulations performed with the WARP code are compared to the experimental data.
Collective dynamics of nuclear fusion: deformation changes and heating during the fusion
International Nuclear Information System (INIS)
Mikhailov, I.N.; Mikhailova, T.I.; Toro, M. di; Baran, V.; Briancon, C.
1996-01-01
The formalism developed elsewhere for the theoretical description of the dynamics involved in the heavy nucleus fusion is applied in this paper to study the history of the fusion of two identical heavy nuclei experiencing central collision. The evolution of the shape and of the temperature of symmetrical fusing systems is studied. The role of the elastoplasticity of nuclear matter in the nonmonotonical changes of the shape is elucidated in this way. A tentative explanation of the ''extra push'' phenomenon is given in terms of the competition between elastic properties of fusing systems driving to the re-separation of colliding nuclei and the dissipative (plastic) properties of nuclear matter transforming the energy of collective motion into the energy of statistical excitation and thus leading to the fusion. The fingerprints of the heavy-nucleus fusion history as it is depicted by the model are traced in the anisotropy of the dipole and quadrupole γ-radiation emitted during the fusion. The parallels in the description of the fusion dynamics given by the simple model used in this paper and by the more fundamental approaches based on the kinetic equation are emphasised. (orig.)
Nuclear quantum effects on the nonadiabatic decay mechanism of an excited hydrated electron
Borgis, Daniel; Rossky, Peter J.; Turi, László
2007-11-01
We present a kinetic analysis of the nonadiabatic decay mechanism of an excited state hydrated electron to the ground state. The theoretical treatment is based on a quantized, gap dependent golden rule rate constant formula which describes the nonadiabatic transition rate between two quantum states. The rate formula is expressed in terms of quantum time correlation functions of the energy gap and of the nonadiabatic coupling. These gap dependent quantities are evaluated from three different sets of mixed quantum-classical molecular dynamics simulations of a hydrated electron equilibrated (a) in its ground state, (b) in its first excited state, and (c) on a hypothetical mixed potential energy surface which is the average of the ground and the first excited electronic states. The quantized, gap dependent rate results are applied in a phenomenological kinetic equation which provides the survival probability function of the excited state electron. Although the lifetime of the equilibrated excited state electron is computed to be very short (well under 100fs), the survival probability function for the nonequilibrium process in pump-probe experiments yields an effective excited state lifetime of around 300fs, a value that is consistent with the findings of several experimental groups and previous theoretical estimates.
Measurements of octupole collectivity in Rn and Ra nuclei using Coulomb excitation
We propose to exploit the unique capability of HIE-ISOLDE to provide post-accelerated $^{221,222}$Rn and $^{222,226,228}$Ra ion beams for the study of octupole collectivity in these nuclei. We will measure E3 transition moments in $^{222}$Rn and $^{222,226,228}$Ra in order to fully map out the variation in E3 strength in the octupole mass region with Z$\\thicksim$88 and N$\\thicksim$134. This will validate model calculations that predict different behaviour as a function of N. We will also locate the position of the parity doublet partner of the ground state in $^{221}$Rn, in order to test the suitability of odd-A radon isotopes for EDM searches.
International Nuclear Information System (INIS)
1996-01-01
In the book there are abstracts collection of the third International radioecological conference 'The fate of spent nuclear fuel: problems and reality' (June, 22-27, 1996, Krasnoyarsk, Russia) and International workshop meeting 'Defence nuclear waste disposal in Russia'. In the collection there are materials concerning the problems of technology, economics, ecology and safety of two types of nuclear cycle as well as the problems of health of population living near nuclear ojects and on contaminated territories
International Nuclear Information System (INIS)
Tas, Murat; Tanatar, B.
2008-01-01
We calculate the collective excitation modes of strongly coupled bilayer charged Bose systems. We employ the dielectric matrix formulation to study the correlation effects within the random-phase approximation (RPA), the self consistent field approximation Singwi, Tosi, Land, and Sjoelander (STLS), and the quasilocalized charge approximation (QLCA), which satisfies the third-frequency-moment ( 3 >) sum rule. We find that the QLCA predicts a long-wavelength correlation-induced energy gap in the out-of-phase plasmon mode, similar to the situation in electronic bilayer systems. The energy gap and the plasmon density of states are studied as a function of interlayer separation and coupling parameter r s . The results should be helpful for experimental investigations
International Nuclear Information System (INIS)
Nesterenko, V.O.; Kleinig, W.
1995-01-01
The self-consistent vibrating potential model (VPM) is extended for description of Eλ collective excitations in atomic nuclei and metal clusters with practically any kind of static deformation. The model is convenient for a qualitative analysis and provides the RPA accuracy of numerical calculations. The VPM is applied to study Eλ giant resonances in spherical metal clusters and deformed and superdeformed nuclei. It is shown that the deformation splitting of superdeformed nuclei results in a very complicated (''jungle-like'') structure of the resonances, which makes the experimental observation of E2 and E3 giant resonances in superdeformed nuclei quite problematic. Calculations of E1 giant resonance in spherical sodium clusters Na 8 , Na 20 and Na 40 are presented, as a test of the VPM in this field. The results are in qualitative agreement with the experimental data. (orig.)
Transverse momentum in high-energy nuclear collisions: Collective expansion
International Nuclear Information System (INIS)
Wang, X.; Hwa, R.C.
1987-01-01
Hadron production in the central region in high-energy nuclear collisions is investigated. The hydrodynamical expansion of a locally thermalized system is studied for both the cases with and without phase transition. The case with phase transition is considered by using a sound-velocity function c/sub s/(T) parametrized to fit the energy density determined in a lattice gauge calculation. The effect of a transverse rarefaction wave is included in the calculation of the temperature profile of the expanding fluid. The transverse-momentum distribution of hadrons is calculated by collecting all the hadrons produced when the hadron gas is cooled down to a freeze-out temperature at different times in the expansion. Fluctuation in initial temperature and radius is allowed due to variation in impact parameter. On the basis of a study of the thermalization process in the parton model we impose a constraint on the initial temperature and the thermalization time, the simultaneous variation of both of which gives rise to a relationship between the average transverse momentum and rapidity density. We have found that there is no so-called ''plateau'' region in that relationship. The implication on the diagnostics of a quark-gluon plasma is discussed
Nuclear matter kinetic coefficients and damping of finite nuclear collective modes
International Nuclear Information System (INIS)
Toledo Piza, A.F.R. de.
1986-06-01
By carrying the general description of one-body observables beyond the mean-field approximation, those correlation terms responsible for Kinetic phenomena and those involved in the renormalization of the G-matrix mean-field in finite nuclei are identified. A Kinetic equation for the one-body density is obtained. Estimates for transport coefficients and for the damping of zero sound are obtained which point to the inadequacy of hydrodynamical descriptions of collective nuclear modes and indicate that collisional damping in large nuclei may account for one or a few tenths of the observed widths. (S.D.) [pt
Chatterji, Tapan; Jalarvo, Niina
2013-04-17
We have investigated the low energy excitations in metallic Ho by high resolution neutron spectroscopy. We found at T = 3 K clear inelastic peaks in the energy loss and energy gain sides, along with the central elastic peak. The energy of this low energy excitation, which is 26.59 ± 0.02 μeV at T = 3 K, decreased continuously and became zero at TN ≈ 130 K. By fitting the data in the temperature range 100-127.5 K with a power law we obtained the power-law exponent β = 0.37 ± 0.02, which agrees with the expected value β = 0.367 for a three-dimensional Heisenberg model. Thus the energy of the low energy excitations can be associated with the order parameter.
International Nuclear Information System (INIS)
Santoyo, B.M.
1989-01-01
The author studies in full detail a possible mechanism of superconductivity in slender electronic systems of finite cross section. This mechanism is based on the pairing interaction mediated by the multiple modes of acoustic plasmons in these structures. First, he shows that multiple non-Landau-damped acoustic plasmon modes exist for electrons in a quasi-one dimensional wire at finite temperatures. These plasmons are of two basic types. The first one is made up by the collective longitudinal oscillations of the electrons essentially of a given transverse energy level oscillating against the electrons in the neighboring transverse energy level. The modes are called Slender Acoustic Plasmons or SAP's. The other mode is the quasi-one dimensional acoustic plasmon mode in which all the electrons oscillate together in phase among themselves but out of phase against the positive ion background. He shows numerically and argues physically that even for a temperature comparable to the mode separation Δω the SAP's and the quasi-one dimensional plasmon persist. Then, based on a clear physical picture, he develops in terms of the dielectric function a theory of superconductivity capable of treating the simultaneous participation of multiple bosonic modes that mediate the pairing interaction. The effect of mode damping is then incorporated in a simple manner that is free of the encumbrance of the strong-coupling, Green's function formalism usually required for the retardation effect. Explicit formulae including such damping are derived for the critical temperature T c and the energy gap Δ 0 . With those modes and armed with such a formalism, he proceeds to investigate a possible superconducting mechanism for high T c in quasi-one dimensional single-wire and multi-wire systems
Wobbling excitation of triaxial nuclear molecule 28Si – 28Si
International Nuclear Information System (INIS)
Uegaki, E; Abe, Y
2013-01-01
High-spin resonances observed in the 28 Si + 28 Si collisions are investigated with a molecular model. At high spins, a stable dinuclear configuration is found to be an equator-equator touching one. Since the E-E configuration is slightly triaxial, rotations of the total system induce mixing of K quantum numbers, called wobbling motion, which clearly explains the particle-γ angular correlations observed as well as the disalignments in a simple and natural way. Furthermore, predictions are given for the angular correlations of the wobbling excited states. The first excited state of wobbling shows strong alignments, which is quite different from the molecular ground state.
International Nuclear Information System (INIS)
Vatin, E.; Guillou, J.; Tephany, F.; Trollat, C.
1993-08-01
This paper presents a study on the dynamic response of piping systems installed in the French 1300 MWe Nuclear Power Plants. Variations in pressure are generated by a multi-staged centrifugal pump mounted on the piping system and provide a dynamic excitation of the pipe. This type of dynamic loading has led to nozzle cracks for some of the pipes, whereas, for other installations, it has not be found detrimental. This study presents an explanation of the different dynamic behavior observed at the various plants. To this end, a numerical model, calibrated with on-site measurements, is impleted. (authors). 8 figs., 1 tab., 5 refs
Nuclear excitations and reaction mechanisms. Progress report, 1 August-31 July 1984
International Nuclear Information System (INIS)
Fallieros, S.; Levin, F.S.
1984-01-01
This progress report describes activities of the Nuclear Theory group at Brown University during the period 1 August 1983 to 31 July 1984. Completed and ongoing research include various theoretical and numerical studies of few-particle systems, nuclear reaction models, nuclear electroexcitation and photon scattering from nuclei. In addition, research on atomic and molecular structure has essentially been concluded and no further DOE-supported research in this area is anticipated
Hyperfine structure in 229gTh3+ as a probe of the 229gTh→ 229mTh nuclear excitation energy.
Beloy, K
2014-02-14
We identify a potential means to extract the 229gTh→ 229mTh nuclear excitation energy from precision microwave spectroscopy of the 5F(5/2,7/2) hyperfine manifolds in the ion 229gTh3+. The hyperfine interaction mixes this ground fine structure doublet with states of the nuclear isomer, introducing small but observable shifts to the hyperfine sublevels. We demonstrate how accurate atomic structure calculations may be combined with the measurement of the hyperfine intervals to quantify the effects of this mixing. Further knowledge of the magnetic dipole decay rate of the isomer, as recently reported, allows an indirect determination of the nuclear excitation energy.
Constraining nuclear photon strength functions by the decay properties of photo-excited states
Isaak, J.; Savran, D.; Krtička, M.; Ahmed, M. W.; Beller, J.; Fiori, E.; Glorius, J.; Kelley, J. H.; Löher, B.; Pietralla, N.; Romig, C.; Rusev, G.; Scheck, M.; Schnorrenberger, L.; Silva, J.; Sonnabend, K.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Zweidinger, M.
2013-12-01
A new approach for constraining the low-energy part of the electric dipole Photon Strength Function (E1-PSF) is presented. Experiments at the Darmstadt High-Intensity Photon Setup and the High Intensity γ→-Ray Source have been performed to investigate the decay properties of 130Te between 5.50 and 8.15 MeV excitation energy. In particular, the average γ-ray branching ratio to the ground state and the population intensity of low-lying excited states have been studied. A comparison to the statistical model shows that the latter is sensitive to the low-energy behavior of the E1-PSF, while the average ground state branching ratio cannot be described by the statistical model in the energy range between 5.5 and 6.5 MeV.
Chiral approach to nuclear matter: role of two-pion exchange with virtual delta-isobar excitation
Fritsch, virtual delta-isobar excitation S.; Kaiser, N.; Weise, W.
2005-04-01
We extend a recent three-loop calculation of nuclear matter by including the effects from two-pion exchange with single and double virtual Δ(1232)-isobar excitation. Regularization dependent short-range contributions from pion-loops are encoded in a few NN-contact coupling constants. The empirical saturation point of isospin-symmetric nuclear matter, E=-16 MeV, ρ=0.16 fm, can be well reproduced by adjusting the strength of a two-body term linear in density (and tuning an emerging three-body term quadratic in density). The nuclear matter compressibility comes out as K=304 MeV. The real single-particle potential U(p,k) is substantially improved by the inclusion of the chiral πNΔ-dynamics: it grows now monotonically with the nucleon momentum p. The effective nucleon mass at the Fermi surface takes on a realistic value of M(k)=0.88M. As a consequence of these features, the critical temperature of the liquid-gas phase transition gets lowered to the value T≃15 MeV. In this work we continue the complex-valued single-particle potential U(p,k)+iW(p,k) into the region above the Fermi surface p>k. The effects of 2 π-exchange with virtual Δ-excitation on the nuclear energy density functional are also investigated. The effective nucleon mass associated with the kinetic energy density is M(ρ)=0.64M. Furthermore, we find that the isospin properties of nuclear matter get significantly improved by including the chiral πNΔ-dynamics. Instead of bending downward above ρ as in previous calculations, the energy per particle of pure neutron matter E(k) and the asymmetry energy A(k) now grow monotonically with density. In the density regime ρ=2ρnuclear physics our results agree well with sophisticated many-body calculations and (semi)-empirical values.
Nuclear excitation via the motion of electrons in a strong laser field
International Nuclear Information System (INIS)
Berger, J.F.; Gogny, D.; Weiss, M.S.
1987-12-01
A method of switching from a nuclear isomeric state to a lasing state is examined. A semi-classical model of laser-electron-nuclear coupling is developed. In it the electrons are treated as free in the external field of the laser, but with initial conditions corresponding to their atomic orbits. Application is made to testing this model in 235 U and to the design criteria of a gamma-ray laser. 14 refs., 2 tabs
Surface and bulk excitations in condensed matter
International Nuclear Information System (INIS)
Ritchie, R.H.
1988-01-01
In this lecture collective and single-particle electron excitations of solids will be discussed with emphasis on the properties of metallic and semiconducting materials. However, some of the general properties of long-wavelength collective modes to be discussed are valid for insulators as well, and some considerations apply to nuclear excitations such as optical or acoustical phonons, dipolar plasmons, etc. The concept of elementary excitations in solids, pioneered by Bohm and Pines almost 4 decades ago, has proved to be extremely useful in understanding the properties of systems of many particles, especially in respect to the response to the action of external probes. 32 refs., 12 figs
International Nuclear Information System (INIS)
Besliu, Calin; Jipa, Alexandru; Argintaru, Dan
2003-01-01
In the last years many experiments have been performed in different laboratories to investigate the behaviour of the nuclear matter formed in nuclear collisions at high energies. Therefore, many experimental results are available at present. For explaining these experimental results a lot of models have been proposed. A very large number of concepts have been used. Taking into account some own experimental results obtained in proton-nucleus and nucleus-nucleus collisions at energies between a few A GeV and a few hundred A GeV we comments in the frame a phenomenological geometric picture the main experimental results on charged particle multiplicities, participants, cross sections, momentum spectra, temperature slopes, nuclear matter flow, size and structure of the participant regions, antiparticle to particle ratios and chemical potential. Some jumps in the dependencies of some interesting physical quantities on the available energies in the centre of mass system can be reported. Trends to behaviours like-saturation of some physical quantities are observed, too. Therefore, some connections with the possible phase transitions in nuclear matter are included. A few specific signals of different phase transitions in nuclear matter are suggested. (authors)
Energy Technology Data Exchange (ETDEWEB)
Barloutaud, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1958-06-15
The following nuclei were excited by protons of 5 MeV maximum energy: {sup 182}W - {sup 184}W - {sup 186}W - {sup 186}Os - {sup 188}Os - {sup 189}Os - {sup 190}Os - {sup 192}Os - {sup 194}Pt - {sup 196}Pt - {sup 198}Pt - {sup 198}Hg - {sup 200}Hg - {sup 202}Hg - {sup 204}Hg - {sup 206}Pb. The reduced probabilities of the various transitions were deduced from the coulomb excitation cross-section measurements. For some even-even nuclei two 2 + levels were excited. The properties of the excited levels are interpreted in terms of the collective model. (author) [French] Au moyen de protons d'energie inferieure a 5 MeV, l'excitation coulombienne des noyaux suivants a ete etudiee: {sup 182}W - {sup 184}W - {sup 186}W - {sup 186}Os - {sup 188}Os - {sup 189}Os - {sup 190}Os - {sup 192}Os - {sup 194}Pt - {sup 196}Pt - {sup 198}Pt - {sup 198}Hg - {sup 200}Hg - {sup 202}Hg - {sup 204}Hg - {sup 206}Pb. La mesure de la section efficace d'excitation coulombienne a permis de deduire les -probabilites reduites des diverses transitions observees. Dans certains noyaux pair-pair, deux niveaux de caractere 2 + ont ete excites. L'interpretation de ces niveaux en termes de niveaux de rotation et de niveaux de vibration a l'aide du modele collectif est discutee. En particulier, la variation des proprietes de ces niveaux avec la deformation nucleaire permet de fixer des limites a la validite des diverses hypotheses entrant dans le modele collectif. (auteur)
Collective motion and giant resonances
International Nuclear Information System (INIS)
Wilhelmi, Z.; Kicinska-Habior, M.
1984-01-01
The report contains 15 papers devoted to problems of giant collective excitations of nuclei, heavy-ion induced reactions and their bearing on various aspects of nuclear structure. In some of them the numerical data are given. (A.S.)
Evolution of collectivity in nuclei
International Nuclear Information System (INIS)
Muralithar, S.
2016-01-01
Nuclear structure studies provide opportunity to understand various modes of excitations and shapes of nucleus as a function of angular momentum, excitation energy and iso-spin. Single particle and collective excitations keep competing and give rise to interesting structures. Phenomena namely back bending, band termination, shape co-existence, rotational bands with different configurations and octupole correlation were reported using gamma ray spectroscopy method. Above nuclear phenomena were studied using Gamma detector array (GDA), Plunger, Heavy Ion Recoil Analyser GDA, Indian National Gamma Array - HlRA at IUAC by various users. Some examples of evolution of collectivity in nuclear structure studies carried out will be presented. (author)
Collective phenomena in non-central nuclear collisions
Energy Technology Data Exchange (ETDEWEB)
Voloshin, Sergei A.; Poskanzer, Arthur M.; Snellings, Raimond
2008-10-20
Recent developments in the field of anisotropic flow in nuclear collision are reviewed. The results from the top AGS energy to the top RHIC energy are discussed with emphasis on techniques, interpretation, and uncertainties in the measurements.
Collective phenomena in non-central nuclear collisions
International Nuclear Information System (INIS)
Voloshin, Sergei A.; Poskanzer, Arthur M.; Snellings, Raimond
2008-01-01
Recent developments in the field of anisotropic flow in nuclear collision are reviewed. The results from the top AGS energy to the top RHIC energy are discussed with emphasis on techniques, interpretation, and uncertainties in the measurements
An historical collection of papers on nuclear thermal propulsion
The present volume of historical papers on nuclear thermal propulsion (NTP) encompasses NTP technology development regarding solid-core NTP technology, advanced concepts from the early years of NTP research, and recent activities in the field. Specific issues addressed include NERVA rocket-engine technology, the development of nuclear rocket propulsion at Los Alamos, fuel-element development, reactor testing for the Rover program, and an overview of NTP concepts and research emphasizing two decades of NASA research. Also addressed are the development of the 'nuclear light bulb' closed-cycle gas core and a demonstration of a fissioning UF6 gas in an argon vortex. The recent developments reviewed include the application of NTP to NASA's Lunar Space Transportation System, the use of NTP for the Space Exploration Initiative, and the development of nuclear rocket engines in the former Soviet Union.
Nuclear power and the public: analysis of collected survey research
Energy Technology Data Exchange (ETDEWEB)
Melber, B.D.; Nealey, S.M.; Hammersla, J.; Rankin, W.L.
1977-11-01
This executive summary highlights the major findings of a comprehensive synthesis and analysis of over 100 existing surveys dealing with public attitudes toward nuclear power issues. Questions of immediate policy relevance to the nuclear debate are posed and answered on the basis of these major findings. For each issue area, those sections of the report in which more-detailed discussion and presentation of relevant data may be found are indicated.
Nuclear power and the public: analysis of collected survey research
International Nuclear Information System (INIS)
Melber, B.D.; Nealey, S.M.; Hammersla, J.; Rankin, W.L.
1977-11-01
This executive summary highlights the major findings of a comprehensive synthesis and analysis of over 100 existing surveys dealing with public attitudes toward nuclear power issues. Questions of immediate policy relevance to the nuclear debate are posed and answered on the basis of these major findings. For each issue area, those sections of the report in which more-detailed discussion and presentation of relevant data may be found are indicated
Prompt muon-induced fission: A probe for nuclear friction in large-amplitude collective motion
International Nuclear Information System (INIS)
Oberacker, V.E.; Umar, A.S.; Wells, J.C.; Strayer, M.R.; Maruhn, J.A.; Reinhard, P.G.
1998-01-01
Excited muonic atoms in the actinide region may induce prompt fission by inverse internal conversion, i.e. the excitation energy of the muonic atom is transferred to the nucleus. The authors solve the time dependent Dirac equation for the muonic spinor wave function in the Coulomb field of the fissioning nucleus on a 3-dimensional lattice and demonstrate that the muon attachment probability to the light fission fragment is a measure of the nuclear energy dissipation between the outer fission barrier and the scission point
International Nuclear Information System (INIS)
Koch, L.
1959-12-01
In the first part is studied the properties of atoms excited by the passage of α particles through the various rare gases at atmospheric pressure. A spectral analysis of the emitted light showed that certain impurities play an important part in producing the fluorescence, and it has led to the conclusion that the light emission contains at least two components - one very short - lived due to the direct deexcitation of the rare gas, the other relatively slower due to the energy transfers to the impurity. The measurement of the life-time of the excited states has confirmed this foregoing hypothesis, the rapid part of the impulse is extremely short: less than 2,25.10 -9 s in the case of xenon; the slower part has a life-time depending directly on the nitrogen concentration, nitrogen being the impurity giving the largest effect in all cases. The study of rare gases under the influence of an electric field has made it possible to show that the amount of light produced by an α particle can be multiplied (by 60, for example, in a field of 600 V:cm) so that the luminescent efficiency is greater than in the case of INaTI. In the second part the characteristics of the rare gases acting as scintillators is examined, the most important property being the absence of fluorescence saturation when the intensity of the excitation incident on the gas is very large. This, together with the very short time of scintillation has made it possible to study a certain number of nuclear physical applications (heavy particle energy-measurements, kinetic studies on nuclear reactors, neutron spectroscopy). (author) [fr
Energy Technology Data Exchange (ETDEWEB)
Mueller-Harvey, Irene, E-mail: i.mueller-harvey@reading.ac.uk [Chemistry and Biochemistry Laboratory, Food Production and Quality Research Division, School of Agriculture, Policy and Development, University of Reading, P O Box 236, Reading RG6 6AT (United Kingdom); Feucht, Walter, E-mail: walter.feucht@gmail.com [Department of Plant Sciences, Technical University of Munich (TUM), Wissenschaftszentrum Weihenstephan (WZW), D-85354 Freising (Germany); Polster, Juergen, E-mail: j.polster@wzw.tum.de [Department of Physical Biochemistry, Technical University of Munich (TUM), Wissenschaftszentrum Weihenstephan (WZW), D-85354 Freising (Germany); Trnkova, Lucie, E-mail: lucie.trnkova@uhk.cz [University of Hradec Kralove, Faculty of Science, Department of Chemistry, Rokitanskeho 62, 50003 Hradec Kralove (Czech Republic); Burgos, Pierre, E-mail: pierre.burgos@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Parker, Anthony W., E-mail: tony.parker@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Botchway, Stanley W., E-mail: stan.botchway@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom)
2012-03-16
is significant nuclear absorption of flavanols. This advanced imaging using two-photon excitation and biophysical techniques described here will prove valuable for probing the intracellular trafficking and functions of flavanols, such as EGCG, which is the major flavanol of green tea.
Nuclear excitations and reaction mechanisms. Progress report, 1 November 1979-30 September 1980
International Nuclear Information System (INIS)
1980-01-01
Among the topics investigated were the following: photon scattering and consistency condition between seagull quadrupole terms and the absorption sum rule; Raman scattering to negative-parity states; nonlocal terms due to exchange and retardation effects in charge-transfer reactions; consistency and meaning of various approximate channel coupling array equations; derivation of equations used in empirical nuclear reaction analyses; multicluster, n-particle scattering theory; converged molecular bound state calculations; consistency of approximate channel coupling array equations; derivations of equations used in empirical nuclear reaction analyses; and WKB-type approximation in angular momenta for central potentials. References to publications are given
International Nuclear Information System (INIS)
Samsonoff, Nathan; Ooms, Matthew D.; Sinton, David
2014-01-01
Excitation of photosynthetic biofilms using surface-confined evanescent light fields enables energy dense photobioreactors, while electrode-adhered biofilms can provide electricity directly. Here, we demonstrate concurrent light delivery and electron transport through a plasmonically excited metal film. Biofilms of cyanobacterium Synechococcus bacillaris on 50-nm gold films are excited via the Kretschmann configuration at λ = 670 nm. Cells show light/dark response to plasmonic excitation and grow denser biofilms, closer to the electrode surface, as compared to the direct irradiated case. Directly irradiated biofilms produced average electrical powers of 5.7 μW/m 2 and plasmonically excited biofilms produced average electrical powers of 5.8 μW/m 2 , with individual biofilms producing as much as 12 μW/m 2
Energy Technology Data Exchange (ETDEWEB)
Samsonoff, Nathan; Ooms, Matthew D.; Sinton, David [Department of Mechanical and Industrial Engineering, and Institute for Sustainable Energy, University of Toronto, Toronto M5S 3G8 (Canada)
2014-01-27
Excitation of photosynthetic biofilms using surface-confined evanescent light fields enables energy dense photobioreactors, while electrode-adhered biofilms can provide electricity directly. Here, we demonstrate concurrent light delivery and electron transport through a plasmonically excited metal film. Biofilms of cyanobacterium Synechococcus bacillaris on 50-nm gold films are excited via the Kretschmann configuration at λ = 670 nm. Cells show light/dark response to plasmonic excitation and grow denser biofilms, closer to the electrode surface, as compared to the direct irradiated case. Directly irradiated biofilms produced average electrical powers of 5.7 μW/m{sup 2} and plasmonically excited biofilms produced average electrical powers of 5.8 μW/m{sup 2}, with individual biofilms producing as much as 12 μW/m{sup 2}.
Jing, Qingli; Bello, Roger Y.; Martín, Fernando; Palacios, Alicia; Madsen, Lars Bojer
2018-04-01
Recent research interests have been raised in uncovering and controlling ultrafast dynamics in excited neutral molecules. In this work we generalize the Monte Carlo wave packet (MCWP) approach to XUV-pump-IR-probe schemes to simulate the process of dissociative double ionization of H2 where singly excited states in H2 are involved. The XUV pulse is chosen to resonantly excite the initial ground state of H2 to the lowest excited electronic state of 1Σu + symmetry in H2 within the Franck-Condon region. The delayed intense IR pulse couples the excited states of 1Σu + symmetry with the nearby excited states of 1Σg + symmetry. It also induces the first ionization from H2 to H2 + and the second ionization from H2 + to H++H+. To reduce the computational costs in the MCWP approach, a sampling method is proposed to determine in time the dominant ionization events from H2 to H2+. By conducting a trajectory analysis, which is a unique possibility within the MCWP approach, the origins of the characteristic features in the nuclear kinetic energy release spectra are identified for delays ranging from 0 to 140 fs and the nuclear dynamics in the singly excited states in H2 is mapped out.
The effect of a neutrino magnetic moment on nuclear excitation processes
International Nuclear Information System (INIS)
Dodd, A.C.; Papageorgiu, E.; Ranfone, S.
1991-01-01
We discuss the sensitivity of magnetic transitions in nuclei like 12 C, to a small neutrino magnetic moment, and its implications for current and future experiments. We also point out that coherent neutrino-nuclear elastic scattering in low-temperature detectors, might improve the present laboratory bounds on the neutrino magnetic moment by an order of magnitude. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Liu, Xiumei; Jin, Zuanming; Lin, Xian; Ma, Guohong [Department of Physics, Shanghai University (China); Cheng, Zhenxiang [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); Balakrishnan, Geetha [Department of Physics, University of Warwick, Coventry (United Kingdom)
2017-09-15
A low-energy collective excitation mode in charge-ordered multiferroic LuFe{sub 2}O{sub 4} is reported via terahertz time-domain spectroscopy. Upon cooling from 300 to 40 K, the central resonance frequency showed a pronounced hardening from 0.85 to 1.15 THz. In analogy to the well-known low-energy optical properties of LuFe{sub 2}O{sub 4}, this emerging resonance was attributed to the charge-density-wave (CDW) collective excitations. By using the Drude-Lorentz model fitting, the CDW collective mode becomes increasingly damped with the increasing temperature. Furthermore, the kinks of the CDW collective mode at the magnetic transition temperature are analyzed, which indicate the coupling of spin order with electric polarization. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
TDHF and fluid dynamics of nuclear collective motions
International Nuclear Information System (INIS)
Di Nardo, M.; Di Toro, M.; Giansiracusa, G.; Lombardo, U.; Russo, G.
1983-01-01
The nuclear fluid dynamical equations are derived from a mean field description of the nuclear dynamics. Simple approximate solutions, corresponding to generalized scaling modes, are worked out for rotations and vibrations, with the evaluation of inertial parameters and flow patterns. Giant resonances are shown to be quite well described within an irrotational ansatz, which is equivalent to a lowest multipoles (up to lsub(max)=2) distortion of the momentum distribution. The physical meaning of a higher order truncation of the TDHF-Fluid-Dynamics chain is finally discussed with its implication on low lying states and on some description of the Landau damping. (author)
International Nuclear Information System (INIS)
Frey, R.W.
1978-01-01
Using high resolution inelastic electron scattering magnitic dipole and quadrupole excitations in 208 Pb were investigated in the energy range between 6 MeV and 8 MeV. The electron energy was 50 MeV and 63.5 MeV. With a mean absolute energy resolution of 33 kev. 44 excited states were found in the above energy range. The measured angular distributions were compared with DWBA-calculations using random phase approximated wave functions. (FKS)
Energy Technology Data Exchange (ETDEWEB)
Doncel, M. [Universidad de Salamanca, Laboratorio de Radiaciones Ionizantes, Salamanca (Spain); Royal Institute of Technology, Department of Physics, Stockholm (Sweden); University of Liverpool, Department of Physics, Oliver Lodge Laboratory, Liverpool (United Kingdom); Gadea, A. [CSIC-University of Valencia, Istituto de Fisica Corpuscular, Valencia (Spain); Valiente-Dobon, J.J. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); Quintana, B. [Universidad de Salamanca, Laboratorio de Radiaciones Ionizantes, Salamanca (Spain); Modamio, V. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); University of Oslo, Oslo (Norway); Mengoni, D. [Dipartimento di Fisica e Astronomia, Universita di Padova, Padova (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Padova (Italy); Moeller, O.; Pietralla, N. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Dewald, A. [Institut fuer Kernphysik, Universitaet Koeln (Germany)
2017-10-15
The current work presents the determination of lifetimes of nuclear excited states using the Recoil Distance Doppler Shift Method, in combination with spectrometers for ion identification, normalizing the intensity of the peaks by the ions detected in the spectrometer as a valid technique that produces results comparable to the ones obtained by the conventional shifted-to-unshifted peak ratio method. The technique has been validated using data measured with the γ-ray array AGATA, the PRISMA spectrometer and the Cologne plunger setup. In this paper a test performed with the AGATA-PRISMA setup at LNL and the advantages of this new approach with respect to the conventional Recoil Distance Doppler Shift Method are discussed. (orig.)
Chatterji, T; Jalarvo, N; Kumar, C M N; Xiao, Y; Brückel, Th
2013-07-17
We have investigated low energy nuclear spin excitations in the strongly correlated electron compound HoCrO3. We observe clear inelastic peaks at E = 22.18 ± 0.04 μeV in both energy loss and gain sides. The energy of the inelastic peaks remains constant in the temperature range 1.5-40 K at which they are observed. The intensity of the inelastic peak increases at first with increasing temperature and then decreases at higher temperatures. The temperature dependence of the energy and intensity of the inelastic peaks is very unusual compared to that observed in other Nd, Co, V and also simple Ho compounds. Huge quasielastic scattering appears at higher temperatures presumably due to the fluctuating electronic moments of the Ho ions that get increasingly disordered at higher temperatures. The strong quasielastic scattering may also originate in the first Ho crystal-field excitations at about 1.5 meV.
QPM Analysis of 205Tl Nuclear Excitations below the Giant Dipole Resonance
Benouaret, N.; Beller, J.; Isaak, J.; Kelley, J. H.; Pai, H.; Pietralla, N.; Ponomarev, V. Yu.; Raut, R.; Romig, C.; Rusev, G.; Savran, D.; Scheck, M.; Schnorrenberger, L.; Sonnabend, K.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Zweidinger, M.
2015-05-01
We analysed our experimental recent findings of the dipole response of the odd-mass stable nucleus 205Tl within the quasi-particle phonon model. Using the phonon basis constructed for the neighbouring 204Hg and wave function configurations for 205Tl consisting of a mixture of quasiparticle ⊗ N-phonon configurations (N=0,1,2), only one group of fragmented dipole excited states has been reproduced at 5.5 MeV in comparison to the experimental distribution which shows a second group at about 5 MeV. The computed dipole transition strengths are mainly of E1 character which could be associated to the pygmy dipole resonance.
QPM Analysis of 205Tl Nuclear Excitations below the Giant Dipole Resonance
Directory of Open Access Journals (Sweden)
Benouaret N.
2015-01-01
Full Text Available We analysed our experimental recent findings of the dipole response of the odd-mass stable nucleus 205Tl within the quasi-particle phonon model. Using the phonon basis constructed for the neighbouring 204Hg and wave function configurations for 205Tl consisting of a mixture of quasiparticle ⊗ N-phonon configurations (N=0,1,2, only one group of fragmented dipole excited states has been reproduced at 5.5 MeV in comparison to the experimental distribution which shows a second group at about 5 MeV. The computed dipole transition strengths are mainly of E1 character which could be associated to the pygmy dipole resonance.
Localized Beampipe Heating due to $e^{-}$ Capture and Nuclear Excitation in Heavy Ion Colliders
Klein, S R
2001-01-01
At heavy ion colliders, two major sources of beam loss are expected to be $e^+e^-$ production, where the $e^-$ is bound to one of the nuclei, and photonuclear excitation and decay via neutron emission. Both processes alter the ions charged to mass ratio by well defined amounts, creating beams of particles with altered magnetic rigidity. These beams will deposit their energy in a localized region of the accelerator, causing localized heating, The size of the target region depends on the collider optics. For medium and heavy ions, at design luminosity at the Large Hadron Collider, local heating may be more than an order of magnitude higher than expected. This could cause magnet quenches if the local cooling is inadequate. The altered-rigidity beams will also produce localized radiation damage. The beams could also be extracted and used for fixed target experiments.
In search of high density collective phenomena in nuclear collision
International Nuclear Information System (INIS)
Gyulassy, M.
1979-06-01
The progress made toward uncovering signatures of collective phenomena is reviewed. Elements of the basic reaction mechanism leading to a complex background are first discussed. Possible hints of collective phenomena in proton and pion single and double inclusive spectra as well as π - multiplicity data are then described. 6 figures, 2 tables
Elementary excitations in nuclei
International Nuclear Information System (INIS)
Lemmer, R.H.
1987-01-01
The role of elementary quasi-particle and quasi-hole excitations is reviewed in connection with the analysis of data involving high-lying nuclear states. This article includes discussions on: (i) single quasi-hole excitations in pick-up reactions, (ii) the formation of single quasi-hole and quasi-particle excitations (in different nuclei) during transfer reactions, followed by (iii) quasi-particle quasi-hole excitations in the same nucleus that are produced by photon absorption. Finally, the question of photon absorption in the vicinity of the elementary Δ resonance is discussed, where nucleonic as well as nuclear degrees of freedom can be excited
Microscopic analysis of nuclear collective motions in terms of the boson expansion theory. Pt. 1
International Nuclear Information System (INIS)
Sakamoto, Hideo; Kishimoto, Teruo
1988-01-01
A normal-ordered linked-cluster boson expansion theory, previously worked out by one of the authors (T.K.) and Tamura, has been developed further by reformulating it in a 'physical' quasiparticle subspace which contains no spurious particle-number excitation modes. The expansion coefficients of the collective hamiltonian for low-lying quadrupole motions are determined starting from a microscopic fermion hamiltonian including self-consistent higher-order (many-body) interactions derived in our previous work. The contributions from the non-collective states with all possible non-collective one-boson excitations having I π = 0 + -4 + , which can directly couple to the collective states with one or two phonons, are taken into account in a systematic and compact way. (orig.)
Theoretical research in nuclear collective motion. Progress report
International Nuclear Information System (INIS)
1984-01-01
Progress is summarized on the following research projects: generalized density matrix method, large amplitude collective motion, boson mappings for the Interacting Boson Model, and semi-classical method for testing IBM hypothesis
Peaceful Uses of Nuclear Energy: A Collection of Speeches
Seaborg, Glenn T.
1970-07-01
It is now a quarter of a century since nuclear energy was introduced to the public. Its introduction was made in the most dramatic, but unfortunately in the most destructive way - through the use of a nuclear weapon. Since that introduction enormous strides have been made in developing the peaceful applications of this great and versatile force. Because these strides have always been overshadowed by the focusing of public attention on the military side of the atom, the public has never fully understood or appreciated the gains and status of the peaceful atom. This booklet is an attempt to correct, in some measure, this imbalance in public information and attitude. It is a compilation of remarks, and excerpts of remarks, that I [Seaborg] have made in recent years in an effort to bring to the public the story of the remarkable benefits the peaceful atom has to offer man. This is a story that grows with the development and progress of the peaceful atom. It must be told so that we can learn to use the power of nuclear energy wisely and through this use help to build a world in which the military applications of the atom will never again be a threat to mankind.
University of Washington Nuclear Physics Data Collection System
International Nuclear Information System (INIS)
Green, K.C.
1981-01-01
During the past several years, a new data collection system has been developed, replacing a previous system based on an SDS-930 computer. The system is constructed about a PDP 11/60 and an MBD-11 controlled CAMAC crate. The hardware configuration as well as a locally written singles data collection code will be described in some detail. Multiparameter data is taken with an enhanced version of Fermilab Multi. Current capabilities and future plans are discussed
Hand held data collection and monitoring system for nuclear facilities
Brayton, D.D.; Scharold, P.G.; Thornton, M.W.; Marquez, D.L.
1999-01-26
Apparatus and method is disclosed for a data collection and monitoring system that utilizes a pen based hand held computer unit which has contained therein interaction software that allows the user to review maintenance procedures, collect data, compare data with historical trends and safety limits, and input new information at various collection sites. The system has a means to allow automatic transfer of the collected data to a main computer data base for further review, reporting, and distribution purposes and uploading updated collection and maintenance procedures. The hand held computer has a running to-do list so sample collection and other general tasks, such as housekeeping are automatically scheduled for timely completion. A done list helps users to keep track of all completed tasks. The built-in check list assures that work process will meet the applicable processes and procedures. Users can hand write comments or drawings with an electronic pen that allows the users to directly interface information on the screen. 15 figs.
Hand held data collection and monitoring system for nuclear facilities
International Nuclear Information System (INIS)
Brayton, D.D.; Scharold, P.G.; Thornton, M.W.; Marquez, D.L.
1999-01-01
Apparatus and method is disclosed for a data collection and monitoring system that utilizes a pen based hand held computer unit which has contained therein interaction software that allows the user to review maintenance procedures, collect data, compare data with historical trends and safety limits, and input new information at various collection sites. The system has a means to allow automatic transfer of the collected data to a main computer data base for further review, reporting, and distribution purposes and uploading updated collection and maintenance procedures. The hand held computer has a running to-do list so sample collection and other general tasks, such as housekeeping are automatically scheduled for timely completion. A done list helps users to keep track of all completed tasks. The built-in check list assures that work process will meet the applicable processes and procedures. Users can hand write comments or drawings with an electronic pen that allows the users to directly interface information on the screen. 15 figs
Excitation of compound states in the subsystems as indirect tool in nuclear astrophysics
Directory of Open Access Journals (Sweden)
Tribble R.E.
2010-03-01
Full Text Available Astrophysical reactions proceeding through compound states represent one of the crucial part of nuclear astrophysics. However, due to the presence of the Coulomb barrier, it is often very difficult or even impossible to obtain the astrophysical S (E factor from measurements in the laboratory at astrophysically relevant energies. The Trojan Horse method (THM provides a unique tool to obtain the information about resonant astrophysical reactions at astrophysically relevant energies. Here the theory and application of the THM for the resonant reactions is addressed.
Nuclear power plants. Guidelines to ensure quality of collected data on reliability
International Nuclear Information System (INIS)
1983-01-01
This international standard lays down guidelines to be followed in the collection of data relative to nuclear power plants so as to ensure the reliability and completeness of the data and its insertion in a computerized system
Selfconsistent diabatic approach to dissipative collective nuclear motion
International Nuclear Information System (INIS)
Niita, K.; Wang, S.J.; Noerenberg, W.; Technische Hochschule Darmstadt
1986-09-01
Within a selfconsistent description for the one- and two-body density matrices collective variables are introduced via scaling diabatic states. Equations of collective motion coupled to a collision integral for the single-particle occupation probabilities are derived from the randomness of the two-body interaction matrix elements and from an additional time smoothing procedure. For a linear approximation to the time-dependence of the single-particle energies the collision term conserves energy all by itself, i.e. the time-smoothed time derivative of the correlation energy vanishes. (orig.)
RAINIER: A simulation tool for distributions of excited nuclear states and cascade fluctuations
Kirsch, L. E.; Bernstein, L. A.
2018-06-01
A new code has been developed named RAINIER that simulates the γ-ray decay of discrete and quasi-continuum nuclear levels for a user-specified range of energy, angular momentum, and parity including a realistic treatment of level spacing and transition width fluctuations. A similar program, DICEBOX, uses the Monte Carlo method to simulate level and width fluctuations but is restricted in its initial level population algorithm. On the other hand, modern reaction codes such as TALYS and EMPIRE populate a wide range of states in the residual nucleus prior to γ-ray decay, but do not go beyond the use of deterministic functions and therefore neglect cascade fluctuations. This combination of capabilities allows RAINIER to be used to determine quasi-continuum properties through comparison with experimental data. Several examples are given that demonstrate how cascade fluctuations influence experimental high-resolution γ-ray spectra from reactions that populate a wide range of initial states.
Study of the nuclear continuum of 28Si after excitation by inelastic 6Li scattering
International Nuclear Information System (INIS)
Seegert, G.
1985-01-01
For the study of the direct reaction mechanisms which contribute in the inelastic 6 Li scattering to the nuclear continuum of 28 Si at the Karlsruhe Isochronous Cyclotron particle-particle coincidence experiments were performed at an incident 6 Li energy of 156 MeV. Thereby the inelastically scattered 6 Li ions were measured in Si semiconductor telescopes under an angle of THETA=11 0 respectively 10 0 , while the coincident charged particles, mainly α particles with an energy of 70 MeV and protons with an energy up to 50 MeV could be detected in an angular range of -85 0 0 and three angles beyond the reaction plane. For a limited angular range simultaneously the α and 3 He fragments produced by the breakup of the 6 Li particle were taken up in coincidence with all light charged particles. (orig./HSI) [de
Accurate measurement of the first excited nuclear state in 235U
Ponce, F.; Swanberg, E.; Burke, J.; Henderson, R.; Friedrich, S.
2018-05-01
We have used superconducting high-resolution radiation detectors to measure the energy level of metastable Um235 as 76.737 ± 0.018 eV. The Um235 isomer is created from the α decay of 239Pu and embedded directly into the detector. When the Um235 subsequently decays, the energy is fully contained within the detector and is independent of the decay mode or the chemical state of the uranium. The detector is calibrated using an energy comb from a pulsed UV laser. A comparable measurement of the metastable Thm229 nucleus would enable a laser search for the exact transition energy in 229Th-Thm229 as a step towards developing the first ever nuclear (baryonic) clock.
Camera aperture to optimize data collection in nuclear medicine
International Nuclear Information System (INIS)
Dupras, G.; Villeneuve, C.
1979-01-01
Collection of data with a large field of view camera can cause problems when a small organ like the heart is to be imaged, especially when high activity is used. A simple, inexpensive mask is described that solves most of these problems. (orig.) [de
International Nuclear Information System (INIS)
Broglia, R.; Hagemann, G.; Herskind, B.
1985-01-01
These proceedings of the Niels Bohr Centennial Conference contains 40 lectures in nuclear physics ranging over the following subjects: single particle motion; collective motion at low excitation energy; collective motion at high angular momentum; giant resonances and nuclear forces. (G.J.P.)
Fetler, Bayard Keith
1993-01-01
Nuclear magnetic resonance (NMR) offers a potential method for making measurements of the percent oxygenation of hemoglobin (Hb) in living tissue non-invasively. As a demonstration of the feasibility of such measurements, we measured the percent oxygenation of Hb in red blood cells (erythrocytes) using resonances in the proton-NMR (^1H-NMR) spectrum which are characteristic of oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb), and are due to the unique magnetic properties of these molecules. To perform these measurements, we developed a new NMR method of selectively exciting signals in a region of interest with uniform phase and amplitude, while suppressing the signal of the water resonance. With this method, we are able to make exact calculations distinguishing between uniform phase excitation produced at large flip-angles using the non-linear properties of the Bloch equations, and uniform phase excitation produced at small flip-angles using asymmetric pulse excitation functions. We measured the percent oxygenation of three characteristic ^1H-NMR resonances of Hb: two from deoxy-Hb, originating from the N_delta H protons of histidine residue F8, which occur at different frequencies for the alpha and beta chains of Hb; and one from oxy-Hb, originating from the gamma_2 -CH_3 protons of valine residue E11. We performed experiments both on fresh erythrocytes and on erythrocytes depleted of 2,3-diphosphoglycerate (2,3-DPG), and found that oxygen is more tightly bound to Hb in the former case. In both fresh and 2,3-DPG-depleted samples, we found that: (i) from the deoxy-Hb marker resonances, there is a small but significant difference in the oxygen saturation between the alpha and beta chains; (ii) the decrease in the areas of the deoxy-Hb marker resonances correlates well with the increase in the percent oxygenation of Hb as measured optically; (iii) the area of the oxy-Hb marker resonance may be up to ~15% less than the optically measured Hb saturation. We are
Physicochemical characteristics of uranium microparticles collected at nuclear fuel cycle plants
International Nuclear Information System (INIS)
Kaurov, G.; Stebelkov, V.; Kolesnikov, O.; Frolov, D.
2001-01-01
Any industrial process is accompanied by appearance of some quantity of microparticles of processed matter in the environment in immediate proximity to the manufacturing object. These particles can be transferred in atmosphere and can be collected at some distances from the plant. The determination of characteristics of industrial dust microparticles at nuclear fuel cycle plants (form, size, structure of surface, elemental composition, isotopic composition, presence of fission products, presence of activation products) in conjunction with the ability to connect these characteristics with certain nuclear manufacturing processes can become the main technical method of detecting of undeclared nuclear activity. Systematization of the experimental data on morphology, elemental and isotopic composition of uranium microparticles, collected at nuclear fuel cycle plants, is given. The purpose of this work is to establish the relationship between morphological characteristics of uranium dust microparticles and types of nuclear manufacture and to define the reference attributes of the most informative microparticles
Collective statement on the role of research in a nuclear regulatory context
International Nuclear Information System (INIS)
2001-01-01
In the present context of deregulation and privatisation of the nuclear industry, maintaining an adequate level of nuclear safety research is a primary concern for nuclear regulators, researchers and nuclear power plant licensees, as well as for government officials and the public. While these different stakeholders may have common concerns and interests, there may also be differences. At the international level, it is important to understand that divisions exist both within and among countries, not only in national cultures but also in the way regulators, researchers and licensees view the rote of research. An international gathering under the auspices of the OECD Nuclear Energy Agency (NEA) took place in June 2001, bringing together heads of nuclear regulatory bodies of NEA Member countries, senior regulators, senior executives of research organisations and leaders from the nuclear industry to discuss their perceptions of the rote of research in a nuclear regulatory context. This collective statement represents an international consensus on a rationale for regulatory research for currently operating nuclear reactors and for future reactors, and sets forth specific recommendations to NEA standing technical committees and Member countries. The intended audience is primarily nuclear safety regulators, senior researchers and industry leaders. Government authorities, nuclear power plant operators and the general public may also be interested. (author)
The proton-neutron interaction and nuclear collectivity
International Nuclear Information System (INIS)
Casten, R.F.
1987-01-01
A review is given of several aspects, and empirical consequences, of the p-n interaction as it relates to the structure, phase transitions and collectivity of medium and heavy nuclei. The N/sub p/N/sub n/ scheme is reviewed as background material while the emphasis centers on a discussion of a related quantity, the P factor, and on the relationship of the integrated strength of the p-n interaction to the empirically observed ''saturation'' of B(E2) values in the mid-shell regions of deformed nuclei. 19 refs., 13 figs
Collection and evaluation of nuclear data of Th-232
International Nuclear Information System (INIS)
Osawa, Takaaki
1979-01-01
Present status of the requirement to and measurement and evaluation of the nuclear data of Th-232 is presented. The accuracy and energy range of the observed data at present are not enough to the demand from reactor engineering. The data of total cross-section are given in the energy range from 1.5 to 15 MeV from the data by Foster and Fasoli. The data by Uttley for the energy less than 1.5 MeV were accepted. Recently, Whalen and Kobayashi presented new data. Optical potential parameters were deduced. Re-normalization of the capture cross-sections of Th-232 was made on the basis of the evaluated values by Matsunobu and by Kanda. The values are a little smaller than the values in ENDF/B-4. Fission cross-sections were given by Henkel up to 9 MeV, and by Rago and Pankratov for the energy range above 9 MeV. Recently, Behrens presented new data for wide energy range. The accuracy of the measured cross-sections of inelastic scattering is not enough for reactor design. The accurate values of the cross-sections of (n, 2n) reaction of Th-232 have been demanded. Resonance parameters have been measured for wide energy range. In the energy range of thermal neutrons, the capture cross-section is about 7.4 barn. The characteristics of velocity dependence of the capture cross-section in this range should be investigated. (Kato, T.)
International Nuclear Information System (INIS)
Matthees, W.; Magiera, G.
1980-01-01
A sensitivity study for the interaction effects for adjacent structures of nuclear power plants i.e. for main buildings and auxiliary buildings has been performed due to horizontal seismic excitation. An interaction measuring rule for response spectra has been defined as the ratio of amplitude of response calculated inclusive the auxiliary building to the amplitude calculated without the auxiliary building in respect to the proper eigen-frequencies. The calculations of the three-dimensional effects are approximated with the program FLUSH. The accuracy of the achievable response herewith calculated is proven in comparison with other suitable methods. The interaction measuring rule is determined by a parameter investigation including the mathematical model consisting of the soil, the main building, and the auxiliary building. The following assumptions are asserted: 1. the soil characteristics are temporarily constant. Ignorance of the accuracy of the realistic i.e. stress depending soil values is encountered by variation of the decisive characteristics within their applicable band-width. 2. The fineness of the mathematical-mechanical modelling for the structural systems i.e. the number of the degrees of freedom is limited to a minimum. Attention is hereby paid that the eigen-frequencies of the main building as well as the eigen-frequencies of the layered soil system in the range of 0 to 10 Hz are computed with sufficient accuracy. (orig./HP) [de
Observation of the exclusive nuclear excitation νe+12C→12Ng.s.+e- in the KARMEN detector
International Nuclear Information System (INIS)
Woelfle, S.
1992-10-01
This report concentrates on the exclusive nuclear excitation ν e + 12 C → 12 N g.s + e - induced by the weak charged current. This reaction is followed by 12 N-decay and has a very high signal to background ratio of 27:1 due to its sequential structure. The flux averaged cross section was measured to be =[7.9±1.1(stat)±0.7(syst)].10 -42 cm 2 . Both the good calorimetric and energy resolution properties of the KARMEN detector enabled the experiment to deduce for the first time an energy dependent cross section for this reaction. The shape and absolute value of the cross section agree well with theoretical predictions. A first search for neutrino oscillations demonstrated the feasilibity of the planned oscillation experiments. Oscillation probabilities P(ν μ →ν e ) ≥ 0.091 and P(anti ν μ →anti ν e ) ≥ 0.045 could be excluded at a 90% confidence level. Thus promising results will be expected at the end of the five years measuring period. (orig.) [de
Coulomb-nuclear interference with 6Li: Isospin character of the 21+ excitation in 70,72,74Ge
International Nuclear Information System (INIS)
Barbosa, M.D.L.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Rodrigues, M.R.D.; Ukita, G.M.
2005-01-01
Ratios of B(E2) to B(IS2), that is, of the reduced quadrupole transition probabilities related, respectively, to charge and mass were extracted through Coulomb-nuclear interference (CNI) for the excitation of the 2 1 + states in 70,72,74 Ge, with a relative accuracy of less than 4%. For this purpose, the CNI angular distributions associated with the inelastic scattering of 28-MeV incident 6 Li ions accelerated by the Sao Paulo Pelletron, and momentum analyzed by the Enge magnetic spectrograph were interpreted within the DWBA-DOMP approach (distorted wave approximation for the scattering process and deformed optical model for the structure representation) with global 6 Li optical parameters. The present CNI results demonstrate an abrupt change in the B(E2)/B(IS2) ratio for 74 Ge: although for 70,72 Ge, values of the order of 1.0 or slightly higher were obtained, this ratio is 0.66 (7) for 74 Ge. The heavier Ge isotope is thus one of the few nuclei that, so far, have been shown to present clear mixed symmetry components in their ground-state band
Nuclear de-excitation processes following medium energy heavy ion collisions
International Nuclear Information System (INIS)
Blann, M.
1986-09-01
As heavy ion reaction studies have progressed from beam energies below 10 MeV/nucleon to higher energies, many non-equilibrium reaction phenomena have been observed. Among these are nucleon emission with velocities in excess of the beam velocity, incomplete momentum transfer to evaporation residue and fission-like fragments, γ-rays with energies in excess of 100 MeV, and π 0 production when beam energies are below the threshold for production by the nucleon-nucleon collision mechanism. Additionally, prefission neutrons have been observed in excess of numbers expected from equilibrium models. A few of the approaches which have been applied to these phenomena are as follows: Intranuclear cascade: two body collisions are assumed to mediate the equilibration. The geometry and momentum space is followed semiclassically. The approach has many successes though it may suffer in a few applications is not following holes; TDHF considers one body processes only; in the energy regime of interest, two body processes are important so that this may not be a viable approach; Boltzmann-Uehling-Uhlenbeck or Vlasov-Uehling-Uhlenbeck (BUU/VUU) equations combine both one body and two body dynamics. The spatial and momentum evolution of the reactions are followed in a mean field. These should be the Cadillacs of the models. They are computationally tedious, and sometimes significant approximations are made in order to achieve computational tract ability; models of collective deceleration. A very simple model approach is discussed to interpret these phenomena, the Boltzmann master equation (BME). The hybrid model was the first to be applied to the question of heavy ion precompound decay, and the BME second. 26 refs., 5 figs., 2 tabs
Collective spin by linearization of the Schrodinger equation for nuclear collective motion
International Nuclear Information System (INIS)
Greiner, M.; Scheid, W.; Herrmann, R.
1988-01-01
The free Schrodinger equation for multipole degrees of freedom is linearized so that energy and momentum operators appear only in first order. As an example, the authors demonstrate the linearization procedure for quadrupole degrees of freedom. The wave function solving this equation carries a spin. The authors derive the operator of the collective spin and its eigen values depending on multipolarity
Heisterkamp, F.; Greilich, A.; Zhukov, E. A.; Kirstein, E.; Kazimierczuk, T.; Korenev, V. L.; Yugova, I. A.; Yakovlev, D. R.; Pawlis, A.; Bayer, M.
2015-12-01
Optically induced nuclear spin polarization in a fluorine-doped ZnSe epilayer is studied by time-resolved Kerr rotation using resonant excitation of donor-bound excitons. Excitation with helicity-modulated laser pulses results in a transverse nuclear spin polarization, which is detected as a change of the Larmor precession frequency of the donor-bound electron spins. The frequency shift in dependence on the transverse magnetic field exhibits a pronounced dispersion-like shape with resonances at the fields of nuclear magnetic resonance of the constituent zinc and selenium isotopes. It is studied as a function of external parameters, particularly of constant and radio frequency external magnetic fields. The width of the resonance and its shape indicate a strong spatial inhomogeneity of the nuclear spin polarization in the vicinity of a fluorine donor. A mechanism of optically induced nuclear spin polarization is suggested based on the concept of resonant nuclear spin cooling driven by the inhomogeneous Knight field of the donor-bound electron.
DEFF Research Database (Denmark)
Larionov, A. V.; Timofeev, V. B.; Hvam, Jørn Märcher
2002-01-01
, and a significant increase in the radiative decay rate of the condensed phase. The collective exciton phase arises at temperatures T properties of the collective phase of interwell excitons and experimental manifestations of this coherence...
Collective effective dose in Europe from x-ray and nuclear medicine procedures
International Nuclear Information System (INIS)
Bly, R.; Jaervinen, H.; Jahnen, A.; Olerud, H.; Vassileva, J.; Vogiatzi, S.
2015-01-01
Population doses from radiodiagnostic (X-ray and nuclear medicine) procedures in Europe were estimated based on data collected from 36 European countries. For X-ray procedures in EU and EFTA countries (except Liechtenstein) the collective effective dose is 547 500 man Sv, resulting in a mean effective dose of 1.06 mSv per caput. For all European countries included in the survey the collective effective dose is 605 000 man Sv, resulting in a mean effective dose of 1.05 mSv per caput. For nuclear medicine procedures in EU countries and EFTA (except Liechtenstein) countries the collective effective dose is 30 700 man Sv, resulting in a mean effective dose of 0.06 mSv per caput. For all European countries included in the survey the collective effective dose is 31 100 man Sv, resulting in a mean effective dose of 0.05 mSv per caput. (authors)
Maintenance planning support method for nuclear power plants based on collective decision making
International Nuclear Information System (INIS)
Shimizu, Shunichi; Sakurai, Shoji; Takaoka, Kazushi; Kanemoto, Shigeru; Fukutomi, Shigeki
1992-01-01
Inspection and maintenance planning in nuclear power plants is conducted by decision making based on experts' collective consensus. However, since a great deal of time and effort is required to reach a consensus among expert judgments, the establishment of effective decision making methods is necessary. Therefore, the authors developed a method for supporting collective decision making, based on a combination of three types of decision making methods; the Characteristic Diagram method, Interpretative Structural Modeling method, and the Analytic Hierarchy Process method. The proposed method enables us to determine the evaluation criteria systematically for collective decision making, and also allows extracting collective decisions using simplified questionnaires. The proposed method can support reaching a consensus of groups effectively through the evaluation of collective decision structural models and their characteristics. In this paper, the effectiveness of the proposed method was demonstrated through its application to the decision making problem concerning whether or not the improved ultrasonic testing equipment should be adopted at nuclear power plants. (author)
Occupational dose reduction developments and data collected at nuclear power plants
International Nuclear Information System (INIS)
Dionne, B.J.; Baum, J.W.
1984-01-01
Occupational dose reduction developments and data collected at nuclear power plants have been described. Written descriptions of repetitive high dose jobs, their collective dose equivalent ranges and list of dose reduction techniques will aid in reducing collective dose equivalents from these dose-reduction targets. Knowing which components contribute to high maintenance or repair dose will aid in reducing routine maintenance collective dose equivalents. The radwaste dose reduction improvements will aid in reducing radwaste operations collective dose equivalent and reduce the number of radwaste workers who exceed their administrative dose limits. The identification and rating of managers' and workers' ALARA incentives will provide the basis for recommendations to improve dose reduction incentives. Lastly, the identification and rating of the key components of an ALARA program will aid in the development and coordination of the nuclear station ALARA programs
Estimated collective effective dose to the population from nuclear medicine examinations in Slovenia
International Nuclear Information System (INIS)
Skrk, Damijan; Zontar, Dejan
2013-01-01
A national survey of patient exposure from nuclear medicine diagnostic procedures was performed by Slovenian Radiation Protection Administration in order to estimate their contribution to the collective effective dose to the population of Slovenia. A set of 36 examinations with the highest contributions to the collective effective dose was identified. Data about frequencies and average administered activities of radioisotopes used for those examinations were collected from all nuclear medicine departments in Slovenia. A collective effective dose to the population and an effective dose per capita were estimated from the collected data using dose conversion factors. The total collective effective dose to the population from nuclear medicine diagnostic procedures in 2011 was estimated to 102 manSv, giving an effective dose per capita of 0.05 mSv. The comparison of results of this study with studies performed in other countries indicates that the nuclear medicine providers in Slovenia are well aware of the importance of patient protection measures and of optimisation of procedures
Analysis of the evolution of the collective dose in nuclear power plants in Spain
International Nuclear Information System (INIS)
Ponjuan Reyes, G.; Ruibia Rodiz, M. A. de la; Rosales Calvo, M.; Labarta Mancho, T.; Calavia Gimenez, I.
2011-01-01
This article presents an analysis of the evolution of occupational collective dose of the Spanish nuclear power planLs during the period 2000 - 2008 within the international context, by the Nuclear SafeLy Council (CSN) in order to have information contrasted to assessing the extent of applicaLion of the ALARA criLeria in the Spanish plants and identify areas of priority attention.
Damping in nuclear collective modes in a semiclassical fluid-dynamical approximation
International Nuclear Information System (INIS)
Vignolo, C.E.; Hernandez, Susana
1989-01-01
A semiclassical fluiddynamical model based on an usual scaling approximation (SCA) was extended to investigate the role of one and two-body dissipation in the widths of nuclear collective modes. The competition between one and two-body viscosity in: i) the collisionless (elastic) limit; ii) the hydrodynamical case and iii) the general viscoelastic regime is examined over the whole range of nuclear collision time scales. Numerical solutions are investigated for the first magnetic 2 - twist mode in 208 Pb. (Author) [es
Activities on collection, evaluation and dissemination of non-neutron nuclear data in the USSR
International Nuclear Information System (INIS)
Grigor'yan, Yu.I.; Ignatochkin, A.E.; Sokolovskij, L.L.; Chukreev, F.E.
1976-01-01
The article describes the present status of collection, evaluation and dissemination of non-neutron nuclear data by the Centre for Data on the Structure of the Atomic Nucleus and Nuclear Reactions, USSR State Committee on the utilization of Atomic Energy. The structure of the Centre itself, its computer facilities and its co-operation with outside organizations are indicated and its functions and plans of activity are considered. (author)
Effective collective dose imparted by a medicine nuclear service to Cordoba and Jaen populations
International Nuclear Information System (INIS)
Arias, M.C.; Galvez, M.; Torres, M.
1997-01-01
The application of diagnostic techniques in nuclear medicine is ever growing as part of clinical daily routine. Although the diagnostic procedures carry a negligible clinical risk, the introduction of radioactive substances into the patient makes it imperative to determine the effective dose to minimize the stochastic effects to the patient thus establishing the collective dose to the community. The aim of our work is to study the collective effective dose imparted by Nuclear Medicine Service during 1997 to Cordoba and Jaen inhabitants (1 448 988). The nuclear medicine techniques of bone exploration with 11 454 mSv-person (4,6 mSv/exploration) and thyroid scintigraphy with 6181 mSv-person (7,0 mSv /exploration) are the main techniques implicated in the relative contribution to the total annual effective collective dose of 35 901.2 mSv-person
It is proposed to investigate the microscopic mechanism which leads to a concentration or a fragmentation of the quadrupole-collective isovector valence-shell excitations, the so-called mixed-symmetry states (MSSs), an effect called shell stabilization of MSSs. This aim will be achieved by identification of MSSs of the unstable nuclei $^{140}$Nd and $^{142}$Sm. The first steps of this program have been undertaken in two subsequent REX-ISOLDE experiments (IS496) in which we have measured the B(E2; 2$^{+}_{1}$$\\rightarrow$ 0$^{+}_{1}$) transition strengths in the radioactive nuclei $^{140}$Nd and $^{142}$Sm. By using these data and the higher beam energy of HIE-ISOLDE we propose now to identify the MSSs of these nuclei by measuring their relative populations with respect to the population of the first 2$^{+}$ states in Coulomb excitation (CE) reactions.
Measurements of octupole collectivity in $^{220,222}$Rn and $^{222,224}$Ra using Coulomb excitation
Kruecken, R; Larsen, A; Hurst, A M; Voulot, D; Grahn, T; Clement, E; Wadsworth, R; Gernhaeuser, R A; Siem, S; Huyse, M L; Iwanicki, J S
2008-01-01
We propose to exploit the unique capability of ISOLDE to provide post-accelerated $^{220,222}$Rn and $^{222,224}$Ra ion beams from the REX facility to enable the Coulomb excitation of the first 3$^{-}$ states in these nuclei. By measuring the $\\gamma$-ray yields of the E1 decays from the 3$^{-}$ state using the MINIBALL array we can obtain the transition matrix elements. This will give quantitative information about octupole correlations in these nuclei. We require 22 shifts to fulfil the aims of the experiment.
International Nuclear Information System (INIS)
Gelston, Gariann M.
2010-01-01
For the Domestic Nuclear Detection Office's Rail Test Center (i.e., DNDO's RTC), port operation knowledge with flexible collection tools and technique are essential in both technology testing design and implementation intended for live operational settings. Increased contextual data, flexibility in procedures, and rapid availability of information are keys to addressing the challenges of optimization, validation, and analysis within live operational setting data collection. These concepts need to be integrated into technology testing designs, data collection, validation, and analysis processes. A modified data collection technique with a two phased live operation test method is proposed.
Fu, Chenghua; Hu, Zhanning
2018-03-01
In this paper, we investigate the characteristics of the nuclear spin entanglement generated by an intermedium with an optically excited triplet. Significantly, the interaction between the two nuclear spins presents to be a direct XY coupling in each of the effective subspace Hamiltonians which are obtained by applying a transformation on the natural Hamiltonian. The quantum concurrence and negativity are discussed to quantitatively describe the quantum entanglement, and a comparison between them can reveal the nature of their relationship. An innovative general equation describing the relationship between the concurrence and negativity is explicitly obtained.
The nuclear deformation versus spin-flip like excitations and the suppression of the 2νββ amplitude
International Nuclear Information System (INIS)
Raduta, A.A.; Delion, D.S.; Faessler, Amand
1997-01-01
We were the first who investigated the influence of spin-flip and non-spin-flip configuration on the separation of the transition amplitude of the Gamow-Teller double beta decay. A realistic Hamiltonian and a projected spherical single particle basis is considered, while the effects are generated by three antagonistic sources: spin-flip, non-spin-flip like excitation and nuclear deformation. Moreover, by a smooth variation of a deformation parameter one could bridge the spherical and deformed pictures. Although our application is not aimed at describing the experimental situation we chose as input data those corresponding to the transition 82 Se → 82 Kr. For near spherical case there are two resonances in M GT , one having a spin-flip structure and identified as GT resonance and one of non-spin-flip structure, placed at low energy. For large deformation and vanishing g pp coupling constant there are two resonances of spin-flip and non-spin-flip natures (ΔI = 1 and 0, respectively) and located at the same energy, what indicates that the deformation acts against the separation of this resonances. In conclusion, our calculation showed that the mechanism of M GT suppression is different for spherical and deformed nuclei. In both cases approaching the critical value of g pp where the RPA breaks down, a lot of strength is accumulated in lowest RPA state and, while in the spherical case this has a non spin-flip nature, in the deformed case the state is a mixture of both types of configurations
International Nuclear Information System (INIS)
Regan, P.H.
2015-01-01
Precision measurements of electromagnetic (EM) transition rates enable tests of models of internal nuclear structure. Measurements of transition rates can be used to infer the spin and parity differences between the initial and final discrete nuclear excited states via which the EM transition takes place. This short conference paper reports on developments of detection systems for the identification of discrete energy gamma-ray decays using arrays of halide-scintillation detectors acting in coincidence mode, which can be used to determine electromagnetic transition rates between excited nuclear states in the sub-nanosecond temporal regime. Ongoing development of a new multi-detector LaBr 3 (Ce) array for studies of exotic nuclei produced at the upcoming Facility for Anti-Proton and Ion Research (FAIR) as part of the NUSTAR–DESPEC project are presented, together with initial results from pre-NUSTAR implementations of this array for nuclear structure studies of neutron-rich fission fragment radionuclides at ILL-Grenoble, France and RIBF at RIKEN, Japan. - Highlights: • This paper reports on new detection systems for identification of gamma decays. • It focusses on using arrays of halide-scintillation detectors in coincidence mode. • These can determine lifetimes of nuclear states at the sub-ns level. • Plans for new LaBr3(Ce) arrays for studies of exotic nuclei are presented.
Collective dose to the European Community from nuclear industry effluents discharge in 1978
Camplin, W C
1983-01-01
The results are presented of a study to evaluate the collective dose commitment to the population of the European Community from effluents released by the nuclear industry within the EC in 1978. Airborne and liquid effluent discharge data have been taken from published sources, and computer modelling techniques have been used to predict the transfer of radioactivity through the environment to man. The collective dose commitments due to discharges from each nuclear installation have been evaluated and the comparative significance of individual radionuclides and their pathways to man have been considered. Airborne releases resulted in an estimated collective effective dose equivalent commitment of 95 man Sv, the major part of which is due to carbon-14 from both power stations and reprocessing plants. The collective effective dose equivalent commitment from liquid effluents is estimated to be 408 man Sv, mostly due to caesium-137 and other radionuclides from the Sellafield (formerly Windscale) reprocessing plant...
Niels Bohr collected works, volume 9: Nuclear physics (1929-1952)
International Nuclear Information System (INIS)
Peierls, R.
1985-01-01
This volume deals with Bohr's work on nuclear physics which began in the pre-1932 days with his thinking deeply, but inconclusively about the seeming contradictions then presented by the evidence about the nucleus. In 1936 Bohr recognized and described the insights provided by neutron scattering experiments and the excitement of this new understanding and its extension and consolidation occupied much of the subsequent years. In 1939 he was again first in understanding the essential features of the newly discovered phenomenon of fission, applying successfully the point of view of nuclear reactions which he had developed over the past three years. Later, in 1949-50, he was impressed by the success of the nuclear shell model, which on the face of it seemed hard to reconcile with the picture of the closely interacting nucleons which he had pioneered in 1936 and he put much effort into clarifying this paradox. As in earlier volumes the published papers are supported by appropriate selections from unpublished notes and drafts, and by relevant correspondence. CONTENTS: Foreword. Part I: Papers and Manuscripts Related to Nuclear Physics. Part II: Selected Correspondence (1929-1949). Inventory of Relevant Manuscripts in the Niels Bohr Archive. Index
Nuclear Engineering Committee KTA. A collection of definitions as of January 16, 1987
International Nuclear Information System (INIS)
Riedel, U.
1987-01-01
The collection of definitions mainly comprises terms which are laid down in the recommendations of the Nuclear Engineering Committee (KTA) or in overriding regulations and specifications. The collection aims at a KTA-standardized use of terms and at the avoidance of groundless divergences. The compiled definitions are followed by a list of the sources considered, namely laws, ordinances, administrative recommendations, KTA regulations as well as other recommendations and standards. (orig./HSCH) [de
Schmid, S.A.; Abbel, R.J.; Schenning, A.P.H.J.; Meijer, E.W.; Herz, L.M.
2010-01-01
We have investigated the extent to which delocalization of the ground-state and excited-state wave functions of a p-conjugated molecule affects the excitation energy transfer (EET) between such molecules. Using femtosecond photoluminescence spectroscopy, we experimentally monitored the EET along
Blazhev, A A; Kruecken, R; Coquard, L; Bloch, T P; Wadsworth, R; Danchev, M T; Jenkins, D G; Kroell, T; Leske, J
It is proposed to initiate an experimental program to study the quadrupole-collective isovector valence-shell excitations the so-called mixed-symmetry states (MSSs) of unstable nuclei from the N = 80 isotonic chain. The main aim of this program is to investigate the microscopic mechanism which leads to a concentration or a fragmentation of the MSSs, an effect dubbed $\\textit{shell stabilization}$ of MSSs. This will be achieved by identification of MSSs of the unstable nuclei $^{140}$Nd and $^{142}$Sm. The MSSs of these nuclei will be identified experimentally by measuring their relative populations with respect to the population of the first 2$^{+}$ states in inverse kinematics Coulomb excitation (CE) reactions on light targets. As a first step of this program we apply for a beam time for the radioactive $^{140}$Nd and $^{142}$Sm beams at beam energy of 2.85 MeV/u. These beams will be used to determine the absolute B(E2;2$_{1}^{+} \\rightarrow$ 0$_{1}^{+}$) values for $^{140}$Nd and $^{142}$Sm in Coulomb excit...
Owen, Robin L; Yorke, Briony A; Pearson, Arwen R
2012-05-01
During X-ray irradiation protein crystals radiate energy in the form of small amounts of visible light. This is known as X-ray-excited optical luminescence (XEOL). The XEOL of several proteins and their constituent amino acids has been characterized using the microspectrophotometers at the Swiss Light Source and Diamond Light Source. XEOL arises primarily from aromatic amino acids, but the effects of local environment and quenching within a crystal mean that the XEOL spectrum of a crystal is not the simple sum of the spectra of its constituent parts. Upon repeated exposure to X-rays XEOL spectra decay non-uniformly, suggesting that XEOL is sensitive to site-specific radiation damage. However, rates of XEOL decay were found not to correlate to decays in diffracting power, making XEOL of limited use as a metric for radiation damage to protein crystals. © 2012 International Union of Crystallography
A guide to archival collections relating to radioactive fallout from nuclear weapon testing
International Nuclear Information System (INIS)
Martin, B.W.
1992-09-01
This ninth edition of A Guide to Archival Collections Relating to Radioactive Fallout from Nuclear Weapon Testing constitutes History Associates Incorporated's (HAI) final report of its document collection, processing, and declassification efforts for the Nevada Field Office of the Department of Energy. The most significant feature of this edition is the updated HAI collection effort information. We confirmed the accuracy of this information using our screening, processing, and transmittal records. Unlike previous editions, funding limitations prevented us from systematically revising the collection descriptions and point-of-contact information for this final edition. This guide has been prepared by professional historians who have a working knowledge of many of the record collections included in the following pages. In describing materials, they have tried to include enough information so that persons unfamiliar with the complexities of large record systems will be able to determine that nature of the information in, and the quality of, each record collection
International Nuclear Information System (INIS)
Hassani, S.
1985-01-01
An old idea of Kramers is to consider nuclear fission as a diffusion process in phase space corresponding to the collective variable of fission. The fission width is taken as an escape rate of the system over the barrier potential. The evolution of the distribution of this collective variable and its conjugate is governed by a Fokker-Planck equation. In a quasistationary treatment Kramers obtained a fission rate which differs from the result given by the transition state method by a friction dependent factor. The non quasistationary solution of the Fokker-Planck equation allows to obtain an escape rate that presents a transient regime: from zero it grows and reaches asymptotically the Kramers' value. This time-dependent fission width is included in a formalism that describes the deexcitation of the compound nucleus in order to calculate the neutron multiplicities in competition with fission. A sensitive friction-dependence of the multiplicities is obtained. Using this formalism and comparing the results with data of a recent experiment gives a good agreement; resolving the disagreement between data and the usual statistical model at high energy. A range of values of the friction coefficient is deduced [fr
Excitation of giant resonances through inelastic scattering
International Nuclear Information System (INIS)
Kailas, S.
1981-01-01
In the last few years, exciting developments have taken place in the study of giant resonances (GR). In addition to the already well known gjant dipole resonance (GDR), the presence of at least two more new GRs viz. giant quadrupole resonance (GQR) and giant monopole resonance (GMR) has been experimentally established. The systematics covering these GRs is found to be consistent with the theoretical expectation. Though the existence of higher multipoles has been predjcted by theory, so far only some of these have been found to be excited experimentally. Various probe particles - electrons, protons (polarized and unpolarized), light and heavy ions and pions - at different bombarding energies have been used to excite the GR region, primarily through the inelastic scattering process. Detailed experiments, looking at the decay modes of GR region, have also been performed. These studies have contributed significantly to a better understanding of the phenomenon of nuclear collective excitation. In this report, the current status of 'GR' research is reviewed. (author)
Giant resonances on excited states
International Nuclear Information System (INIS)
Besold, W.; Reinhard, P.G.; Toepffer, C.
1984-01-01
We derive modified RPA equations for small vibrations about excited states. The temperature dependence of collective excitations is examined. The formalism is applied to the ground state and the first excited state of 90 Zr in order to confirm a hypothesis which states that not only the ground state but every excited state of a nucleus has a giant resonance built upon it. (orig.)
Investigations of collective and single-particle aspects of excitation in 1fsub(7/2) shell nuclei
International Nuclear Information System (INIS)
Styczen, J.
1976-01-01
Experimental data are presented which were obtained in spectroscopic studies on 1fsub(7/2) shell nuclei in the following reactions: 30 Si( 16 0,pn) 44 Sc, 44 Ca(p,n) 44 Sc, 42 Ca(α,p) 45 Sc, 42 Ca(α,n) 45 Sc, 45 Sc(α,pn) 47 Ti, 46 Ti(α,p) 49 V, 47 Ti(α,pn) 49 V, and 49 Ti(p,n) 49 V. Experimental reduced transition probabilities B(M1) and B(E2) have been systematically compared for inband transitions of Ksup(π)=3/2 + bands in sup(43,45,47)Sc, 45 Ti and sup(47,49)V nuclei. In the framework of the pure rotational model, intrinsic quadrupole moments |Qsub(o)| and |gsub(K)-gsub(R)| ratios have been derived. Band mixing calculations in a strong coupling model treating more correctly the j 2 term in the hamiltonian and hole excitations, have been indertaken on properties of negativeparity states in the cross-conjugate nuclei 47 Ti- 49 V and V 47 - 49 Dr. There is an overall good agreement between the experimental data and the theoretical predictions. The strong coupling model has been also used to study possible regions of stable deformation for the positive parity states of the odd nuclei in the 1fsub(7/2) shell. Band mixing calculations performed for these states have shown that the experimental data are well reproduced in the calculations with a deformation parameter corresponding to a minimum of the static potential energy. (author)
International Nuclear Information System (INIS)
Dupont, E.
2012-01-01
The NEA Data Bank is an international centre of reference for basic nuclear tools used in the analysis and prediction of phenomena in different nuclear applications. The Data Bank collects and compiles computer codes and scientific data and contributes to their improvement for the benefit of scientists in its member countries. In line with this mission, the Data Bank is a core centre of the International Network of Nuclear Reaction Data Centres (NRDC), which co-ordinates the worldwide collection, compilation and dissemination of nuclear reaction data. The NRDC network was established in 1976 from the earlier Four-Centres' Network created in 1966 by the United States, the NEA, the International Atomic Energy Agency (IAEA) and the former Soviet Union. Today, the NRDC is a worldwide co-operation network under the auspices of the IAEA, with 14 nuclear data centres from 8 countries and 2 international organisations belonging to the network. The main objective of the NRDC is to preserve, update and disseminate experimental nuclear reaction data that have been compiled for more than 40 years in a shared database (EXFOR). The EXFOR database contains basic nuclear data on low- to medium-energy experiments for incident neutron, photon and various charged-particle-induced reactions on a wide range of isotopes, natural elements and compounds. Today, with more than 140 000 data sets from approximately 20 000 experiments, EXFOR is by far the most important and complete experimental nuclear reaction database in the world and is widely used in the field of nuclear science and technology. The Data Bank is responsible for the collection and compilation of nuclear reaction data measured in its geographical area. Since 1966, the Data Bank has contributed around 5 000 experiments to the EXFOR database, and it continues to compile new data while maintaining the highest level of quality throughout the database. NRDC co-ordination meetings are held on a biennial basis. Recent meetings
Hutter, Jürg
2003-03-01
An efficient formulation of time-dependent linear response density functional theory for the use within the plane wave basis set framework is presented. The method avoids the transformation of the Kohn-Sham matrix into the canonical basis and references virtual orbitals only through a projection operator. Using a Lagrangian formulation nuclear derivatives of excited state energies within the Tamm-Dancoff approximation are derived. The algorithms were implemented into a pseudo potential/plane wave code and applied to the calculation of adiabatic excitation energies, optimized geometries and vibrational frequencies of three low lying states of formaldehyde. An overall good agreement with other time-dependent density functional calculations, multireference configuration interaction calculations and experimental data was found.
International Nuclear Information System (INIS)
Oland, C.B.
1995-04-01
A program is being conducted at the Oak Ridge National Laboratory (ORNL to assist the Nuclear Regulatory Commission (NRC)) in their assessment of the effects of degradation (primarily corrosion) on the structural capacity and leaktight integrity of metal containments and steel liners of reinforced concrete structures in nuclear power plants. One of the program objectives is to characterize and quantify manifestations of corrosion on the properties of steels used to construct containment pressure boundary components. This report describes a plan for use in collecting and presenting data and information on ferrous alloys permitted for use in construction of pressure retaining components in concrete and metal containments. Discussions about various degradation mechanisms that could potentially affect the mechanical properties of these materials are also included. Conclusions and recommendations presented in this report will be used to guide the collection of data and information that will be used to prepare a material properties data base for containment steels
Collection and evalution of abnormal occurrences in German nuclear power plants
International Nuclear Information System (INIS)
Hoffmeister
1976-01-01
The systematic consideration of operating experiences which must be recorded, collected and evaluated, is important for the realisation of the aim of greater safety in nuclear power stations. Since commissioning of the first nuclear power stations in West Germany all significant events were communicated to the 'Laender' authorities responsible for controlling compliance with the licensing requirements. The evaluation of these events assured that the necessary consequences were carried out to prevent any recurrence. A systematic consideration of the operating experiences, however, was missing; therefore our institute was made responsible by the Federal Ministry of the Interior with the agreement of the 'Laender' authorities to record, collect and evaluate in accordance with reporting criteria and a classification system related to safety relevance. (orig./RW) [de
The nuclear data collecting system designed with ARM and μC/OS-II
International Nuclear Information System (INIS)
Wang Chunsheng; Ma Yingjie; Han Feng
2008-01-01
Introduce a kind of nuclear data collecting system regarding ARM-μC/OS-II as the platform, gathering the GPS receiver in it. It was detailed to expatiated the key techniques of the multi-channel pulse amplitude analyzer, the interface design of LPC2148, a controller in ARM, and how to expand the RTOS and design applications on μC/OS-II. This system can communicate with the GPS-OEM module by the UART interface, collecting the GPS information synchronously as well as nuclear data. And then save and display them or pass them to the host computer by the USB interface. The embedded and Real-Time system, μC/OS-II build up the real-time and stability of the system and advance the integration. (authors)
International Nuclear Information System (INIS)
1991-01-01
This Safety Practice is the first in a series of reports under the programme on the management of nuclear power plant ageing. The purpose of the programme is to facilitate the exchange of information and to promote co-operation among Member States towards understanding and managing the ageing degradation of components, with the aim of maintaining safe and reliable plant operation. The availability and evaluation of appropriate data on nuclear power plant components are essential to safety and constitute a key factor in plant life extension considerations. The present publication provides guidance on data requirements and an effective and practical system for data collection and record keeping in relation to the evaluation and management of ageing and service life. This guidance is based on current practices. It is envisaged that the application of the guidance will contribute to the safe and reliable operation of nuclear power plants and will facilitate international information exchange on ageing related component failures, malfunctions and degradation, since data collected using the same ground rules would be easier to exchange and compare. The guidance is intended primarily for the management, maintenance and technical staff of nuclear power plants, on whom the ultimate success of the recommended system and its associated benefits depend. Intended secondary audiences include utility management and central technical support organizations, regulatory bodies, standards organizations, design companies, and research and development institutes. 8 refs, 1 fig., 1 tab
Collective effects on transport coefficients of relativistic nuclear matter. Pt. 2
International Nuclear Information System (INIS)
Mornas, L.
1993-04-01
The transport coefficients (thermal conductivity, shear and bulk viscosities) of symmetric nuclear matter and neutron matter are calculated in the Walecka model with a Boltzmann-Uehling-Uhlenbeck collision term by means of a Chapman-Enskog expansion in first order. The order of magnitude of the influence of collective effects induced by the presence of the mean σ and ω fields on these coefficients is evaluated. (orig.). 9 figs
International Nuclear Information System (INIS)
Lucherini, V.; Bianchi, N.; De Sanctis, E.; Guaraldo, C.; Levi Sandri, P.; Muccifora, V.; Polli, E.; Reolon, A.R.; Aiello, S.; De Filippo, E.; Lanzano', G.; Lo Nigro, S.; Milone, C.; Pagano, A.; Botvina, A.S.; Iljinov, A.S.; Mebel, M.V.
1990-01-01
The mechanisms of excitation with subsequent fission of heavy nuclei can be conveniently studied by means of photons, since this probe is able to interact deeply inside the nucleus. We propose the use of the (200-1200 MeV) tagged photon beam from the ADONE Jet Target in order to study the mass-energy and total momentum distributions of fission fragments, to obtain experimental information on the configurations (excitation energy and nucleonic composition) of produced compound nuclei and on their decay channels
Kosarev, V. A.; Kuznetsova, E. E.
2014-02-01
The possibility of applying dusty active media in nuclearpumped lasers has been considered. The amplification of 1790-nm radiation in a nuclear-excited dusty He - Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He - Ar medium containing 10-nm nanoclusters of metallic uranium and uranium dioxide.
International Nuclear Information System (INIS)
Li Zuyu; He Zhiyong; Duan Limin; Jin Genming; Wu Heyu; Zhang Baoguo; Wen Wanxin; Qi Yujin; Luo Qingzheng; Dai Guangxi; Wang Hongwei
1997-01-01
Nuclear temperatures extracted from excited state populations were measured as a function of linear momentum transfer (LMT) for 40 Ar+ 197 Au reactions at 25MeV/nucleon. The emission temperatures increased slightly with increasing linear momentum transfer or decreasing impact parameter. Taking into account the corrections of detection efficiency and sequential feeding from higher-lying states, a temperature of T∼4MeV was deduced for central collisions. For peripheral collisions the extracted temperatures increased with the energy of the particles. (orig.)
International Nuclear Information System (INIS)
Manenti, Simone; Alí Santoro, María del Carmen; Cotogno, Giulio; Duchemin, Charlotte; Haddad, Ferid; Holzwarth, Uwe; Groppi, Flavia
2017-01-01
Deuteron-induced nuclear reactions for the generation of 103 Pd were investigated using the stacked-foil activation technique on rhodium targets at deuteron energies up to E d = 33 MeV. The excitation functions of the reactions 103 Rh(d,xn) 101,103 Pd, 103 Rh(d,x) 100g,cum,101m,g,102m,g Rh and 103 Rh(d,2p) 103 Ru have been measured, and the Thick-Target Yield for 103 Pd has been calculated.
International Nuclear Information System (INIS)
2010-01-01
Collection of research papers I All-Russian scientific-practical conference of young nuclear scientists in Siberia, held 19-25 September 2010 in Tomsk, is presented. The edition contains material on a wide range of research scientists-economists, professors, graduate students and young scientists, and school children of Tomsk, Seversk, and several other Russian cities on the technology, security, ecology, economics, management in the nuclear power industry. Discussion of the presented research was conducted on sections: 1. Technological support for the nuclear fuel cycle, 2. Nuclear non-proliferation and environmental safety of the nuclear fuel cycle, 3. Energy: Present and Future 4. It all starts with an idea [ru
International Nuclear Information System (INIS)
Santos, S.H.C.; Castro Monteiro, I. de
1986-01-01
The seismic requests to be considered in the project of main buildings of a nuclear power plant are discussed. The models for global seismic analysis of nuclear power plant structures, as well as models for global strength distribution are presented. The models for analysing reactor auxiliary building and control building, which together with the reactor building and turbine building form the main energy generation complex in a nuclear power plant, are described. (M.C.K.) [pt
Nuclear quantum many-body dynamics: from collective vibrations to heavy-ion collisions
International Nuclear Information System (INIS)
Simenel, Cedric
2012-01-01
This report gives a summary of my research on nuclear dynamics during the past ten years. The choice of this field has been motivated by the desire to understand the physics of complex systems obeying quantum mechanics. In particular, the interplay between collective motion and single-particle degrees of freedom is a source of complex and fascinating behaviours. For instance, giant resonances are characterised by a collective vibration of many nucleons, but their decay may occur by the emission of a single nucleon. Another example could be taken from the collision of nuclei where the transfer of few nucleons may have a strong impact on the formation of a compound system is non trivial. To describe these complex systems, one needs to solve the quantum many-body problem. The description of the dynamics of composite systems can be very challenging, especially when two such systems interact. An important goal of nuclear physics is to find a unified way to describe the dynamics of nuclear systems. Ultimately, the same theoretical model should be able to describe vibrations, rotations, fission, all the possible outcomes of heavy-ion collisions (elastic and inelastic scattering, particle transfer, fusion, and multifragmentation), and even the dynamics of neutron star crust. This desire for a global approach to nuclear dynamics has strongly influenced my research activities. In particular, all the numerical applications presented in this report have been obtained from few numerical codes solving equations derived from the same variational principle. Beside the quest for a unified model of nuclear dynamics, possible applications of heavy-ion collisions such as the formation of new nuclei is also a strong motivation for the experimental and theoretical studies of reaction mechanisms. This report is not a review article, but should be considered as a reading guide of the main papers my collaborators and myself have published. It also gives the opportunity to detail some
Yuzefovsky, A I; Lonardo, R F; Michel, R G
1995-07-01
A single 90 degrees off-axis ellipsoidal mirror fragment was used in a dispersive detection system for electrothermal atomization laser-excited atomic fluorescence spectrometry. The performance of the new optical arrangement was compared with those of optical arrangements that employed a plane mirror in combination with biconvex or plano-convex lenses. All the optical arrangements collected fluorescence in a scheme called front surface illustration. BEAM-4, an optical ray tracing program, was used for calculations of spatial ray distributions and optical collection efficiency for the various optical configurations. Experimentally, the best collection efficiency was obtained by use of the ellipsoidal mirror, in qualitative agreement with simulations done by use of the BEAM-4 software. The best detection limit for cobalt with the new optical arrangement was 20 fg, which was a factor of 5 better than that obtained with conventional optical arrangements with otherwise the same instrumentation. The signal-to-background ratio and the fluorescence collection efficiency were also studied as a function of position of the optical components for the various optical arrangements. For both cobalt and phosphorus, the signal-to-background ratio with the new optical arrangement remained stable within 10-20% during +/- 8 mm shifts in the position of the detection system from the focal plane of the optics. Overall, the new optical arrangement offered high collection efficiency, excellent sensitivity, and facile optical alignment due to efficient spatial separation between the fluorescence signal and the background radiation. The advantages of the new optical arrangement were particularly important during measurements in the presence of high levels of blackbody radiation.
Lim, Edward C
2013-01-01
Excited States, Volume 2 is a collection of papers that deals with molecules in the excited states. The book describes the geometries of molecules in the excited electronic states. One paper describes the geometries of a diatomic molecule and of polyatomic molecules; it also discusses the determination of the many excited state geometries of molecules with two, three, or four atoms by techniques similar to diatomic spectroscopy. Another paper introduces an ordered theory related to excitons in pure and mixed molecular crystals. This paper also presents some experimental data such as those invo
Lim, Edward C
1982-01-01
Excited States, Volume 6 is a collection of papers that discusses the excited states of molecules. The first paper discusses the linear polyene electronic structure and potential surfaces, considering both the theoretical and experimental approaches in such electronic states. This paper also reviews the theory of electronic structure and cites some experimental techniques on polyene excitations, polyene spectroscopic phenomenology, and those involving higher states of polyenes and their triplet states. Examples of these experimental studies of excited states involve the high-resolution one-pho
Bray, James William [Niskayuna, NY; Garces, Luis Jose [Niskayuna, NY
2012-03-13
The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.
Vibrational motions in rotating nuclei studied by Coulomb excitations
Energy Technology Data Exchange (ETDEWEB)
Shimizu, Yoshifumi R [Kyushu Univ., Fukuoka (Japan). Dept. of Physics
1998-03-01
As is well-known Coulomb excitation is an excellent tool to study the nuclear collective motions. Especially the vibrational excitations in rotating nuclei, which are rather difficult to access by usual heavy-ion fusion reactions, can be investigated in detail. Combined with the famous 8{pi}-Spectrometer, which was one of the best {gamma}-ray detector and had discovered some of superdeformed bands, such Coulomb excitation experiments had been carried out at Chalk River laboratory just before it`s shutdown of physics division. In this meeting some of the experimental data are presented and compared with the results of theoretical investigations. (author)
International Nuclear Information System (INIS)
Li Wenfei; Zhang Fengshou; Chen Liewen
2001-01-01
Within the framework of Hartree-Fock theory using the extended Skyrme effective interaction, the isospin excitation energy as a function of relative neutron excess δ was investigated at different temperatures and densities. It was found that the isospin excitation energy decreased with the increment of temperature and/or the decrement of density. The authors pointed out that the decrement of isospin excitation energy was resulted from the weakening of quantum effect with increment of temperature and/or decrement of density. Meanwhile, the relationship between the isospin excitation energy and the symmetry energy was discussed and found that the symmetry energy was just a part of the isospin excitation energy. With increasing temperature and decreasing density, the contribution of the symmetry energy to the isospin excitation energy becomes more and more important. The isospin excitation energy as a function of relative neutron excess was also investigated using different potential parameters. The results shows that the isospin excitation energy is almost independent of the incompressibility and the effective mass, but strongly depends on the symmetry energy strength coefficient, which indicates that it is possible to extract the symmetry energy of the nuclear equation of state by investigating the isospin excitation energy in experiments
Energy Technology Data Exchange (ETDEWEB)
Ponjuan Reyes, G.; Ruibia Rodiz, M. A. de la; Rosales Calvo, M.; Labarta Mancho, T.; Calavia Gimenez, I.
2011-07-01
This article presents an analysis of the evolution of occupational collective dose of the Spanish nuclear power plants during the period 2000 - 2008 within the international context, by the Nuclear Safety Council (CSN) in order to have information contrasted to assessing the extent of application of the ALARA criteria in the Spanish plants and identify areas of priority attention.
Directory of Open Access Journals (Sweden)
Qian-Xing Zhuang
2012-09-01
Full Text Available The superior vestibular nucleus (SVN, which holds a key position in vestibulo-ocular reflexes and nystagmus, receives direct hypothalamic histaminergic innervations. By using rat brainstem slice preparations and extracellular unitary recordings, we investigated the effect of histamine on SVN neurons and the underlying receptor mechanisms. Bath application of histamine evoked an excitatory response of the SVN neurons, which was not blocked by the low-Ca2+/high-Mg2+ medium, indicating a direct postsynaptic effect of the amine. Selective histamine H1 receptor agonist 2-pyridylethylamine and H2 receptor agonist dimaprit, rather than VUF8430, a selective H4 receptor agonist, mimicked the excitation of histamine on SVN neurons. In addition, selective H1 receptor antagonist mepyramine and H2 receptor antagonist ranitidine, but not JNJ7777120, a selective H4 receptor antagonist, partially blocked the excitatory response of SVN neurons to histamine. Moreover, mepyramine together with ranitidine nearly totally blocked the histamine-induced excitation. Immunostainings further showed that histamine H1 and H2 instead of H4 receptors existed in the SVN. These results demonstrate that histamine excites the SVN neurons via postsynaptic histamine H1 and H2 receptors, and suggest that the central histaminergic innervation from the hypothalamus may actively bias the SVN neuronal activity and subsequently modulate the SVN-mediated vestibular functions and gaze control.
International Nuclear Information System (INIS)
Teles, Pedro; Vaz, Pedro; Paulo, Graciano; Santos, Joana; Pascoal, Ana; Lanca, Isabel; Matela, Nuno; Sousa, Patrick; Carvoeiras, Pedro; Parafita, Rui; Simaozinho, Paula
2013-01-01
In order to assess the exposure of the Portuguese population to ionizing radiation due to medical examinations of diagnostic radiology and nuclear medicine, a working group, consisting of 40 institutions, public and private, was created to evaluation the coletive dose in the Portuguese population in 2010. This work was conducted in collaboration with the Dose Datamed European consortium, which aims to assess the exposure of the European population to ionizing radiation due to 20 diagnostic radiology examinations most frequent in Europe (the 'TOP 20') and nuclear medicine examinations. We obtained an average value of collective dose of ≈ 1 mSv/caput, which puts Portugal in the category of countries medium to high exposure to Europe. We hope that this work can be a starting point to bridge the persistent lack of studies in the areas referred to in Portugal, and to enable the characterization periodic exposure of the Portuguese population to ionizing radiation in the context of medical applications
Energy Technology Data Exchange (ETDEWEB)
Gilson, Erik P.; Davidson, Ronald C.; Efthimion, Philip C.; Majeski, Richard; Startsev, Edward A.; Wang, Hua [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Koppell, Stewart [University of Texas at Austin, Austin, Texas 78712 (United States); Talley, Matthew [Brigham Young University, Provo, Utah 84602 (United States)
2013-05-15
Transverse dipole and quadrupole modes have been excited in a one-component cesium ion plasma trapped in the Paul Trap Simulator Experiment (PTSX) in order to characterize their properties and understand the effect of their excitation on equivalent long-distance beam propagation. The PTSX device is a compact laboratory Paul trap that simulates the transverse dynamics of a long, intense charge bunch propagating through an alternating-gradient transport system by putting the physicist in the beam's frame of reference. A pair of arbitrary function generators was used to apply trapping voltage waveform perturbations with a range of frequencies and, by changing which electrodes were driven with the perturbation, with either a dipole or quadrupole spatial structure. The results presented in this paper explore the dependence of the perturbation voltage's effect on the perturbation duration and amplitude. Perturbations were also applied that simulate the effect of random lattice errors that exist in an accelerator with quadrupole magnets that are misaligned or have variance in their field strength. The experimental results quantify the growth in the equivalent transverse beam emittance that occurs due to the applied noise and demonstrate that the random lattice errors interact with the trapped plasma through the plasma's internal collective modes. Coherent periodic perturbations were applied to simulate the effects of magnet errors in circular machines such as storage rings. The trapped one component plasma is strongly affected when the perturbation frequency is commensurate with a plasma mode frequency. The experimental results, which help to understand the physics of quiescent intense beam propagation over large distances, are compared with analytic models.
STRENGTH DISTRIBUTIONS IN NEODYMIUM ISOTOPES - A TEST OF COLLECTIVE NUCLEAR-MODELS
PIGNANELLI, M; BLASI, N; BORDEWIJK, JA; DELEO, R; HARAKEH, MN; HOFSTEE, MA; MICHELETTI, S; PERRINO, R; PONOMAREV, VY; SOLOVIEV, VG; SUSHKOV, AV; VANDERWERF, SY
1993-01-01
Excite states n even N isotopes, up to excitation energies of 3-4 MeV, were investigate in proton- and deuteron-scattering experiments performed with high-energy resolution. More than 300 transitions were studied. For several new excited states spin and parity assignments have been suggested.
International Nuclear Information System (INIS)
Anon.
1979-01-01
This Guide is intended to establish a method of collecting and presenting reliability data for quantitative systematic reliability analysis in nuclear power generating stations, as outlined in IEEE Std 351-1975. Appendix D, which is not a part of IEEE Std 500-1977 but which comprises the bulk of this publication, presents tables of reliability data for nuclear power generating stations, intended for use of nuclear systems reliability analysts or design engineers
Production of a diffuse very high reflectivity material for light collection in nuclear detectors
Pichler, B J; Mirzoyan, R; Weiss, L; Ziegler, S I
2000-01-01
A diffuse very high reflectivity material, based on polytetrafluorethylene (PTFE) for optimization of light-collection efficiency has been developed. PTFE powder was used to produce reflector block material. The powder was pressed with 525 kPa in a form and sintered at 375 deg. C. The reflectivity was above 98% within the spectral range from 350 to 1000 nm. The blocks of this material are machinable with saws, drilling and milling machines. The reflector is used as a housing for scintillating crystals in a nuclear medicine application (small animal positron emission tomograph). It is also used as a light collector in very high-energy gamma-ray astrophysicas experiments, HEGRA and MAGIC. The application of this inexpensive, easy to make diffuse reflector may allow the optimization of light collection in a wide range of low-level light-detector configurations.
International Nuclear Information System (INIS)
Fitzgerald, Peter; Laughter, Mark D.; Martyn, Rose; Richardson, Dave; Rowe, Nathan C.; Pickett, Chris A.; Younkin, James R.; Shephard, Adam M.
2010-01-01
Accountability scale data from the Global Nuclear Fuels (GNF) fuel fabrication facility in Wilmington, NC has been collected and analyzed as a part of the Cylinder Accountability and Tracking System (CATS) field trial in 2009. The purpose of the data collection was to demonstrate an authentication method for safeguards applications, and the use of load cell data in cylinder accountability. The scale data was acquired using a commercial off-the-shelf communication server with authentication and encryption capabilities. The authenticated weight data was then analyzed to determine facility operating activities. The data allowed for the determination of the number of full and empty cylinders weighed and the respective weights along with other operational activities. Data authentication concepts, practices and methods, the details of the GNF weight data authentication implementation and scale data interpretation results will be presented.
Path-integral in collective variables and its application to nuclear and hadron physics
International Nuclear Information System (INIS)
Pervushin, V.N.; Rajnkhardt, Kh.; Ehbert, D.
1979-01-01
The application of functional integrals to describe collective degrees of freedom in different fields of physics is reviewed for the period since 1965. The application of path integrals to the schematic model of nuclear multiparticle systems with pairing and particle-hole forces permits to lay strict foundations under the so called theory of nuclear field, which hitherto was proved euristically. The Abel gauge theory of interacting massless quarks and vector gluons is described. In this model radiative corrections cause spontaneous dynamic breaking of the chiral γ 5 -invariance. The application of functional integration to two-dimensional quantum chromodynamics is also analyzed. It is shown that the local quark-gluon theory can be transformed in an infinite-component nonpolynomial field theory in terms of colourless bound states - mesons. A modified perturbation theory appears in the form of 1/Nsub(c)-expansion (Nsub(c) - number of quarks), that is formally is very akin to the 1/Ω-expansion (Ωdegeneracy of single-particle states) in the theory of nuclear field
Directory of Open Access Journals (Sweden)
M. Yiğit
2017-08-01
Full Text Available In this paper, nuclear data for cross sections of the 64Zn(n,2n63Zn, 64Zn(n,3n62Zn, 64Zn(n,p64Cu, 66Zn(n,2n65Zn, 66Zn(n,p66Cu, 67Zn(n,p67Cu, 68Zn(n,p68Cu, and 68Zn(n,α65Ni reactions were studied for neutron energies up to 40 MeV. In the nuclear model calculations, TALYS 1.6, ALICE/ASH, and EMPIRE 3.2 codes were used. Furthermore, the nuclear data for the (n,2n and (n,p reaction channels were also calculated using various cross-section systematics at energies around 14–15 MeV. The code calculations were analyzed and obtained using the different level densities in the exciton model and the geometry-dependent hybrid model. The results obtained from the excitation function calculations are discussed and compared with literature experimental data, ENDF/B-VII.1, and the TENDL-2015 evaluated data.
Energy Technology Data Exchange (ETDEWEB)
Yigit, M. [Faculty of Science and Arts, Dept. of Physics, Aksaray University, Aksaray (Turkmenistan); Kara, A. [Faculty of Engineering, Department of Energy Systems Engineering, Giresun University, Giresun (Turkmenistan)
2017-08-15
In this paper, nuclear data for cross sections of the {sup 64}Zn(n,2n){sup 63}Zn,{sup 64}Zn(n,3n){sup 62}Zn, {sup 64}Zn(n,p){sup 64}Cu, {sup 66}Zn(n,2n){sup 65}Zn, {sup 66}Zn(n,p){sup 66}Cu, {sup 67}Zn(n,p){sup 67}Cu, {sup 68}Zn(n,p){sup 68}Cu, and {sup 68}Zn(n,α){sup 65}Ni reactions were studied for neutron energies up to 40 MeV. In the nuclear model calculations, TALYS 1.6, ALICE/ASH, and EMPIRE 3.2 codes were used. Furthermore, the nuclear data for the (n,2n) and (n,p) reaction channels were also calculated using various cross-section systematics at energies around 14–15 MeV. The code calculations were analyzed and obtained using the different level densities in the exciton model and the geometry-dependent hybrid model. The results obtained from the excitation function calculations are discussed and compared with literature experimental data, ENDF/B-VII.1, and the TENDL-2015 evaluated data.
International Nuclear Information System (INIS)
Sabaton, M.; Morilhat, P.; Savoldelli, D.; Genette, P.
1995-10-01
Electricite de France (EDF), the french national electricity company, is operating 54 standardized pressurizer water reactors. This about 500 reactor-years experience in nuclear stations operation and maintenance area has allowed EDF to develop its own strategy for monitoring of age-related degradations of NPP systems and components relevant for plant safety and reliability. After more than fifteen years of experience in regulatory transient data collection and seven years of successful fatigue monitoring prototypes experimentation, EDF decided to design a new system called SYSFAC (acronym for SYsteme de Surveillance en FAtigue de la Chaudiere) devoted to transient logging and thermal fatigue monitoring of the reactor coolant pressure boundary. The system is fully automatic and directly connected to the on-site data acquisition network without any complementary instrumentation. A functional transient detection module and a mechanical transient detection module are in charge of the general transient data collection. A fatigue monitoring module is aimed towards a precise surveillance of five specific zones particularly sensible to thermal fatigue. After the first step of preliminary studies, the industrial phase of the SYSFAC project is currently going on, with hardware and software tests and implementation. The first SYSFAC system will be delivered to the pilot power plant by the beginning of 1996. The extension to all EDF's nuclear 900 MW is planned after one more year of feedback experience. (authors). 12 refs., 3 figs
Energy Technology Data Exchange (ETDEWEB)
Uddin, Md. Shuza [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM), Nuklearchemie (INM-5); Atomic Energy Research Establishment, Dhaka (Bangladesh). Tandem Accelerator Facilities; Chakraborty, Animesh Kumer [Chittagong Univ. of Engineering and Technology (Bangladesh). Dept. of Physics; Atomic Energy Research Establishment, Dhaka (Bangladesh). Tandem Accelerator Facilities; Spellerberg, Stefan; Spahn, Ingo; Qaim, Syed M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM), Nuklearchemie (INM-5); Shariff, Md. Asad [Atomic Energy Research Establishment, Dhaka (Bangladesh). Tandem Accelerator Facilities; Rashid, Md. Abdur [Chittagong Univ. of Engineering and Technology (Bangladesh). Dept. of Physics
2017-07-01
Excitation functions for the formation of the radionuclides {sup 56}Co, {sup 57}Co, {sup 58m+g}Co and {sup 54}Mn via proton induced reactions on natural iron target were measured from their respective thresholds up to 16 MeV using the stacked-foil activation technique and HPGe detector γ-ray spectroscopy. In the threshold energy range, the low cross sections for {sup 54}Mn were measured radiochemically. All the measured values were compared with available experimental data and with theoretical calculations reproduced in TENDL-2015 nuclear data library. New data for the formation of {sup 57}Co, {sup 58}Co and {sup 54}Mn were obtained near their reaction thresholds. Other data obtained strengthen the database. Polynomial fittings of the data measured in this work as well as of all data sets (including the present data) were performed. The present data appear to be closer to theoretical calculations than the literature data.
International Nuclear Information System (INIS)
Usman, Ahmed Rufai; Khandaker, Mayeen Uddin; Haba, Hiromitsu; Otuka, Naohiko; Murakami, Masashi
2017-01-01
Highlights: • Detailed presentation of new results on experimental cross-sections of "n"a"tTi(α,x) processes. • Calculations of thick target yields for scandium and other radionuclides via the "n"a"tTi(α,x) production route. • Comparison with TENDL-2015 library. • Detailed review of previous experimental data. - Abstract: We studied the excitation functions of residual radionuclide productions from α particles bombardment on natural titanium in the energy range of 10.4–50.2 MeV. A well-established stacked-foil activation technique combined with HPGe γ-ray spectrometry was used to measure the excitation functions for the "5"1","4"9","4"8Cr, "4"8V, "4"3K, and "4"3","4"4"m","4"4"g","4"6"g"+"m","4"7","4"8Sc radionuclides. The thick target yields for all assessed radionuclides were also calculated. The obtained experimental data were compared with the earlier experimental ones and also with the evaluated data in the TENDL-2015 library. A reasonable agreement was found between this work and some of the previous ones, while a partial agreement was found with the evaluated data. The present results would further enrich the experimental database and facilitate the understanding of existing discrepancies among the previous measurements. The results would also help to enhance the prediction capability of the nuclear reaction model codes.
International Nuclear Information System (INIS)
Allan, M.; Regeta, K.; Gorfinkiel, J.D.; Masin, Z.; Grimme, S.; Bannwarth, C.
2016-01-01
The article briefly reviews three subjects recently investigated in Fribourg: 1) electron collisions with surfaces of ionic liquids, 2) two-dimensional (2D) electron energy loss spectra and 3) resonances in absolute cross sections for electronic excitation of unsaturated compounds. Electron energy loss spectra of four ionic liquids revealed a number of excited states, including triplet states. A solution of a dye in an ionic liquid showed an energy-loss band of the solute, but not in all ionic liquids. 2D spectra reveal state-to-state information (given resonance to given final state) and are shown to be an interesting means to gain insight into dynamics of nuclear motion in resonances. Absolute cross sections for pyrimidine are reported as a function of scattering angle and as a function of electron energy. They reveal resonant structure which was reproduced very nicely by R-matrix calculations. The calculation provided an assignment of the resonances which reveals common patterns in compounds containing double bonds. (authors)
Energy Technology Data Exchange (ETDEWEB)
Usman, Ahmed Rufai [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Department of Physics, Umaru Musa Yar' adua University, Katsina (Nigeria); Khandaker, Mayeen Uddin, E-mail: mu_khandaker@um.edu.my [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Haba, Hiromitsu [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Otuka, Naohiko [Nuclear Data Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, A-1400 Vienna (Austria); Murakami, Masashi [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan)
2017-05-15
Highlights: • Detailed presentation of new results on experimental cross-sections of {sup nat}Ti(α,x) processes. • Calculations of thick target yields for scandium and other radionuclides via the {sup nat}Ti(α,x) production route. • Comparison with TENDL-2015 library. • Detailed review of previous experimental data. - Abstract: We studied the excitation functions of residual radionuclide productions from α particles bombardment on natural titanium in the energy range of 10.4–50.2 MeV. A well-established stacked-foil activation technique combined with HPGe γ-ray spectrometry was used to measure the excitation functions for the {sup 51,49,48}Cr, {sup 48}V, {sup 43}K, and {sup 43,44m,44g,46g+m,47,48}Sc radionuclides. The thick target yields for all assessed radionuclides were also calculated. The obtained experimental data were compared with the earlier experimental ones and also with the evaluated data in the TENDL-2015 library. A reasonable agreement was found between this work and some of the previous ones, while a partial agreement was found with the evaluated data. The present results would further enrich the experimental database and facilitate the understanding of existing discrepancies among the previous measurements. The results would also help to enhance the prediction capability of the nuclear reaction model codes.
International Nuclear Information System (INIS)
Cojazzi, Giacomo G.M.; Van Der Goot, Erik; Verile, Marco; Wolfart, Erik; Rutan Fowler, Marcy; Feldman, Yana; Hammond, William; Schweighardt, John; Ferguson, Mattew
2013-01-01
Acquisition and analysis of open source information plays an increasingly important role in the IAEA’s move towards safeguards implementation based on all safeguards relevant information known about a State. The growing volume of open source information requires the development of technology and tools capable of effectively collecting relevant information, filtering out “noise”, organizing valuable information in a clear and accessible manner, and assessing its relevance. In this context, the IAEA’s Division of Information Management (SGIM) and the EC’s Joint Research Centre (JRC) are currently implementing a joint project to advance the effectiveness and efficiency of the IAEA’s workflow for open source information collection and analysis. The objective is to provide tools to support SGIM in the production of the SGIM Open Source Highlights, which is a daily news brief consisting of the most pertinent news stories relevant to safeguards and non-proliferation. The process involves the review and selection of hundreds of articles from a wide array of specifically selected sources. The joint activity exploits the JRC’s Europe Media Monitor (EMM) and NewsDesk applications: EMM automatically collects and analyses news articles from a pre-defined list of web sites, and NewsDesk allows an analyst to manually select the most relevant articles from the EMM stream for further processing. The paper discusses the IAEA’s workflow for the production of SGIM Open Source Highlights and describes the capabilities of EMM and NewsDesk. It then provides an overview of the joint activities since the project started in 2011, which were focused i) on setting up a separate EMM installation dedicated to the nuclear safeguards and security domain (Nuclear Security Media Monitor, NSMM) and ii) on evaluating the NSMM/NewsDesk for meeting the IAEA’s needs. Finally, it presents the current use NSMM/NewsDesk at the IAEA and proposes options for further integration with the
Pivin, J C
2002-01-01
The growth of silver clusters in co-sputtered SiO sub 2 :Ag films under irradiation with increasing fluences of 1.5 MeV He or 3 MeV Au ions is investigated by recording spectra of optical extinction. The analysis of surface plasmon resonances in these very small clusters on basis of Mie theory permits to estimate more precisely their mean size than TEM images. A linear increase of the mean cluster size with the energy deposited by ions in electronic excitations and little effect of collision cascades are observed. The growth kinetics is ascribed to a process of desorption/re-adsorption of Ag atoms at the surface of clusters.
Selected topics in nuclear structure
International Nuclear Information System (INIS)
Solov'ev, V.G.; Gromov, K.Ya.; Malov, L.A.; Shilov, V.M.
1994-01-01
The Fourth International Conference on selected topics in nuclear structure was held at Dubna in July 1994 on recent experimental and theoretical investigations in nuclear structure. Topics discussed were the following: nuclear structure at low-energy excitations (collective quasiparticle phenomena, proton-neutron interactions, microscopic and phenomenological theories of nuclear structure; nuclear structure studies with charged particles. heavy ions, neutrons and photons; nuclei at high angular momenta and superdeformation, structure and decay properties of giant resonances, charge-exchange resonances and β-decay; semiclassical approach of large amplitude collective motion and structure of hot nuclei
Selected topics in nuclear structure
Energy Technology Data Exchange (ETDEWEB)
Solov` ev, V G; Gromov, K Ya; Malov, L A; Shilov, V M
1994-12-31
The Fourth International Conference on selected topics in nuclear structure was held at Dubna in July 1994 on recent experimental and theoretical investigations in nuclear structure. Topics discussed were the following: nuclear structure at low-energy excitations (collective quasiparticle phenomena, proton-neutron interactions, microscopic and phenomenological theories of nuclear structure; nuclear structure studies with charged particles). heavy ions, neutrons and photons; nuclei at high angular momenta and superdeformation, structure and decay properties of giant resonances, charge-exchange resonances and {beta}-decay; semiclassical approach of large amplitude collective motion and structure of hot nuclei.
Mcpeak, W. L.
1975-01-01
A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.
Spurious Excitations in Semiclassical Scattering Theory.
Gross, D. H. E.; And Others
1980-01-01
Shows how through proper handling of the nonuniform motion of semiclassical coordinates spurious excitation terms are eliminated. An application to the problem of nuclear Coulomb excitation is presented as an example. (HM)
Can Measured Synergy Excitations Accurately Construct Unmeasured Muscle Excitations?
Bianco, Nicholas A; Patten, Carolynn; Fregly, Benjamin J
2018-01-01
Accurate prediction of muscle and joint contact forces during human movement could improve treatment planning for disorders such as osteoarthritis, stroke, Parkinson's disease, and cerebral palsy. Recent studies suggest that muscle synergies, a low-dimensional representation of a large set of muscle electromyographic (EMG) signals (henceforth called "muscle excitations"), may reduce the redundancy of muscle excitation solutions predicted by optimization methods. This study explores the feasibility of using muscle synergy information extracted from eight muscle EMG signals (henceforth called "included" muscle excitations) to accurately construct muscle excitations from up to 16 additional EMG signals (henceforth called "excluded" muscle excitations). Using treadmill walking data collected at multiple speeds from two subjects (one healthy, one poststroke), we performed muscle synergy analysis on all possible subsets of eight included muscle excitations and evaluated how well the calculated time-varying synergy excitations could construct the remaining excluded muscle excitations (henceforth called "synergy extrapolation"). We found that some, but not all, eight-muscle subsets yielded synergy excitations that achieved >90% extrapolation variance accounted for (VAF). Using the top 10% of subsets, we developed muscle selection heuristics to identify included muscle combinations whose synergy excitations achieved high extrapolation accuracy. For 3, 4, and 5 synergies, these heuristics yielded extrapolation VAF values approximately 5% lower than corresponding reconstruction VAF values for each associated eight-muscle subset. These results suggest that synergy excitations obtained from experimentally measured muscle excitations can accurately construct unmeasured muscle excitations, which could help limit muscle excitations predicted by muscle force optimizations.
Estimating collective dose in nuclear facilities, with emphasis on the design process
International Nuclear Information System (INIS)
Cohen, S.; Mann, B.
1987-01-01
The report presents a more accurate, systematic method than has been available previously for predicting worker doses which might be incurred during routine and non-routine work in radioactive areas. Besides assisting regulators with an analysis of the ''potential impact on radiological exposures of facility employees'' now required under the new backfit rule (10 CFR 50.109c), this predictive model will also help licensees conserve dollars as well as dose because it can be employed very early in the engineering design phase of a modification, when adjustments can still be made easily to change orders. Such early estimates make good business sense because they will facilitate planning, labor loading, costing, resource and equipment scheduling, and overall coordination of both single and repetitive projects. Also, with the support of corporate management, radiation protection coordinators can introduce the model into training programs to acquaint design engineers and others with dose calculation techniques. The importance assigned by nuclear industry senior management to the principle of ALARA and the reduction of collective worker dose is measured, in large part, by demonstrated efforts to integrate the control of radiation exposure fully into the overall planning function of nuclear facility management. That integration will be fostered through the use of this approach
2002-01-01
The aim of this experiment is twofold:\\\\ \\\\ Firstly to test the possibilities of collection of the heavy recoil nuclei with the device presented schematically on the figure. The recoil nuclei escaping from the irradiated target are first thermalised in a gas (N^2). One then takes advantage of their remaining charge to collect them with an electric field on the surface of a solid state detector. Tests already performed with other beams give absolute efficiency around 5\\%. The best conditions of collections with very energetic |1|2C have first to be tested. Secondly to get some insight into nuclear reaction mechanisms induced by 86~MeV/a.m.u. |1|2C using the possibilities of this recoil chamber. Two kinds of mechanisms should occur in these interactions. If the incident energy is damped (deep inelastic reaction, fusion), the heavy nucleus will be highly excited and the residual nuclei will lie along the @G^n/@G^p~=~1~line. For heavy nuclei this line is located at about 25~mass units from the stability line. If ...
International Nuclear Information System (INIS)
David, Cherine; Arumugam, Brinda; Rajamani, Amuda; Natarajan, Kanimozhi
2014-01-01
This paper describes the physics of collective excitations that are caused by spin-transfer torques in CFAS magnetic multilayer. When the magnetizations of the pinned and free layers are not collinear with each other, the spin-polarized currents transfer angular momentum to the magnetizations near the interfaces, giving rise to spin-transfer torques. The currents in magnetic multilayer are spin polarised and can carry enough angular momentum. When an electron spin carried by the current interacts with a magnetic layer, the exchange interaction leads to torque between the spin and the magnetization vector of the free layer. This is Spin Transfer Torque (STT) and it excites the magnetization when it is large enough. The Spin Transfer Torque induced collective excitations for the CFAS spin valve pillar have been extensively studied in this paper. - Highlights: • We have modeled LLGS equation for CFAS multilayer array. • The dynamics of collective excitation induced by STT is investigated. • The interactions exhibit solitonic behaviour at both limiting modes of polarization. • The spin components of the solitons are graphically represented
Basis states for the rotational and vibrational limits of nuclear collective motion
International Nuclear Information System (INIS)
Vanagas, V.; Alishauskas, S.; Kalinauskas, R.; Nadzhakov, E.
1980-01-01
Basis states characterized by quantum numbers traditionally used in the rotational and the vibrational limits are treated in an unified way. An explicit basis construction in the Hilbert space of the collective phenomenological nuclear Hamiltonian generalized to six degrees of freedom in both limits is given. This generalization reduces to including an additional degree of freedom allowing to treat both cases within a collective substance of the complete many-body Hilbert space. A group-theoretical approach is applied. From this point of view the problem is reduced to the construction of a set of U(6)-irreducible states labelled by quantum numbers of two special chains of subgroups adapted for the rotational and vibrational limits. In particular, the generalization is more complicated in the case of the chain for the rotational limits. The explicit construction of a basis for both limits is carried out in two steps: 1) construction of the highest weight state for corresponding group irreducible representation - in the case of the rotational limit U(3) and of the vibrational limit O(5); 2) generating a complete set of states by the projection technique. In this framework it is possible to diagonalize a general phenomenological Hamiltonian in cases different from both limits. It is also possible to calculate transition probabilities induced by any physical quantity
International Nuclear Information System (INIS)
Hilaire, S.; Girod, M.; Goriely, S.
2011-01-01
The combinatorial model of nuclear level densities has now reached a level of accuracy comparable to that of the best global analytical expressions without suffering from the limits imposed by the statistical hypothesis on which the latter expressions rely. In particular, it provides naturally, non Gaussian spin distribution as well as non equipartition of parities which are known to have a significant impact on cross section predictions at low energies. Our first global model developed in Ref. 1 suffered from deficiencies, in particular in the way the collective effects - both vibrational and rotational - were treated. We have recently improved this treatment using simultaneously the single particle levels and collective properties predicted by a newly derived Gogny interaction, therefore enabling a microscopic description of energy-dependent shell, pairing and deformation effects. In addition, for deformed nuclei, the transition to sphericity is coherently taken into account on the basis of a temperature-dependent Hartree-Fock calculation which provides at each temperature the structure properties needed to build the level densities. This new method is described and shown to give promising preliminary results with respect to available experimental data. (authors)
The collection of symposium reports for people to understand nuclear power
International Nuclear Information System (INIS)
1988-07-01
It deals with the symposium reports which gives people public information on nuclear power. It introduces the programs on public information and measures in France, Japan, Canada, Korea. It reports the presentations of the result which are the education programs for children and people about safety of nuclear power, nuclear power plant and environmental disruption, safety insurance of nuclear power and the present condition of operating nuclear power plant.
International Nuclear Information System (INIS)
Barbashev, S.V.
2001-01-01
Large scope of problems is presented. Operation of nuclear power enterprises, introduction of safety culture principles in them, situation with the training of specialists, role of youth in nuclear fuel complex and others are discussed. Reports of participants which were submitted at the conference are presented
Energy Technology Data Exchange (ETDEWEB)
Chang, Jong Hwa; Lee, Jeong Yeon; Lee, Young Ouk; Sukhovitski, Efrem Sh [Korea Atomic Energy Research Institute, Taejeon (Korea)
2000-01-01
Programs SHEMMAN and OPTMAN (Version 6) have been developed for determinations of nuclear Hamiltonian parameters and for optical model calculations, respectively. The optical model calculations by OPTMAN with coupling schemes built on wave functions functions of non-axial soft-rotator are self-consistent, since the parameters of the nuclear Hamiltonian are determined by adjusting the energies of collective levels to experimental values with SHEMMAN prior to the optical model calculation. The programs have been installed at Nuclear Data Evaluation Laboratory of KAERI. This report is intended as a brief manual of these codes. 43 refs., 9 figs., 1 tabs. (Author)
National Research Council Canada - National Science Library
Holzricher, John
2004-01-01
To more easily obtain a voiced excitation function for speech characterization, measurements of skin motion, tracheal tube, and vocal fold, motions were made and compared to EM sensor-glottal derived...
Wright, Bradford L.
1975-01-01
Advocates the creation of swimming pool oscillations as part of a general investigation of mechanical oscillations. Presents the equations, procedure for deriving the slosh modes, and methods of period estimation for exciting swimming pool oscillations. (GS)
International Nuclear Information System (INIS)
Feng Renfa; Zhang Jingshang; Ma Zhongyu; Wu Xizhen; Zhuo Yizhong
1984-01-01
In this paper the Hamiltonian model is used for studying the nuclear dynamics by taking both the one-body and two-body interaction mechanisms into account. On the basis of the Von Neuman equation the coupling between the collective motion and the single particle degrees of freedom is discussed. Thus, the equations obtained are physically transparent and easy for numerical computations. They may be useful for describing the dissipative process of the nuclear collective motion as well as the equilibration process of the intrinsic degrees of freedom. (Author)
Lim, Edward C
1974-01-01
Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab
Using (n,xnγ) reactions to probe collective nuclear structure
International Nuclear Information System (INIS)
Yates, S.W.; Brown, T.B.; Warr, N.; Hannant, C.D.
2000-01-01
Complete text of publication follows. The (n,n'γ) reaction has been utilized at the University of Kentucky accelerator laboratory for many years to study the structure of stable nuclei (1,2). Through the use of γ-ray excitation function and angular distribution measurements, detailed level schemes of stable nuclei can be established. In recent years, the Doppler-shift attenuation method (DSAM) has been applied following the inelastic neutron scattering reaction to determine the lifetimes of nuclear states (3), and collimated neutron 'beams' have been employed in γ-γ coincidence measurements with an array of HPGe detectors in a close geometry (4,5). Recently, γ-ray detection facilities (6,7) for reactions induced by spallation neutrons, with energies of several hundred MeV, have become available at the Los Alamos Neutron Science Center (LANSCE), and initial measurements indicate that a large variety of reactions are possible. Evidence has been obtained for reactions with as many as 27 particles emitted (7). While the mechanisms of such reactions may be of interest, the primary spectroscopic advantage of utilizing higher-energy neutrons appears to be that neutron-rich nuclei which are not normally available for study with fusion-evaporation reactions can be accessed. As a complement to these measurements with very energetic neutrons, (n2nγ) and (n,3nγ) reaction studies have been explored with neutrons from the 2 H(d,n) and 3 H(d,n) reactions and the facilities at the University of Kentucky. Neutron energies as high as 22 MeV have been employed. Initial evaluations have focussed on data from the 186 W(n,2nγ) 185 W and 186 W(n,3nγ) 184 W reactions and indicate that a great deal of information can be obtained. The advantages of these measurements, as well as comparisons with data from reactions with spallation neutrons, will be presented. This work was supported under grant PHY-9803784 from the U.S. National Science Foundation. (author)
Energy Technology Data Exchange (ETDEWEB)
Kesner, A [University of Colorado, Anschutz Medical Campus, Aurora, Colorado (United States); Poli, G [International Atomic Energy Agency, Vienna, Vienna (Austria); Beykan, S; Lassman, M [University of Wuerzburg, Wuerzberg, Wuerzberg (Germany)
2016-06-15
Purpose: As the field of Nuclear Medicine moves forward with efforts to integrate radiation dosimetry into clinical practice we can identify the challenge posed by the lack of standardized dose calculation methods and protocols. All personalized internal dosimetry is derived by projecting biodistribution measurements into dosimetry calculations. In an effort to standardize organization of data and its reporting, we have developed, as a sequel to the EANM recommendation of “Good Dosimetry Reporting”, a freely available biodistribution template, which can be used to create a common point of reference for dosimetry data. It can be disseminated, interpreted, and used for method development widely across the field. Methods: A generalized biodistribution template was built in a comma delineated format (.csv) to be completed by users performing biodistribution measurements. The template is available for free download. The download site includes instructions and other usage details on the template. Results: This is a new resource developed for the community. It is our hope that users will consider integrating it into their dosimetry operations. Having biodistribution data available and easily accessible for all patients processed is a strategy for organizing large amounts of information. It may enable users to create their own databases that can be analyzed for multiple aspects of dosimetry operations. Furthermore, it enables population data to easily be reprocessed using different dosimetry methodologies. With respect to dosimetry-related research and publications, the biodistribution template can be included as supplementary material, and will allow others in the community to better compare calculations and results achieved. Conclusion: As dosimetry in nuclear medicine become more routinely applied in clinical applications, we, as a field, need to develop the infrastructure for handling large amounts of data. Our organ level biodistribution template can be used as a
Symplectic dynamics of the nuclear mean-field
International Nuclear Information System (INIS)
Grigorescu, Marius
1996-01-01
Collective and microscopic pictures of the nuclear dynamics are related in the frame of time-dependent variational principle on symplectic trial manifolds. For symmetry braking systems such manifolds are constructed by cranking, and applied to study the nuclear isovector collective excitations. (author)
International Nuclear Information System (INIS)
Newton, G.J.; Hoover, M.D.; Barr, E.B.; Wong, B.A.; Ritter, P.D.
1982-01-01
Decommissioning of radioactively contaminated sites has the potential for creating radioactive and other potentially toxic aerosols. We describe an experimental system to collect and characterize aerosols from metal cutting activities typical of those used in decommissioning of nuclear facilities. A special enclosure was designed for the experiment and consisted of a 2-in. x 4-in. stud frame with double walls of flame retardant polyethylene film. Large plexiglass windows allowed the cutting operations to be directed and filmed. Ventilation was 8500 L/min (300 CFM) exhausted through HEPA filters. Seven cutting techniques were evaluated: pipe cutter, reciprocating saw, band saw, chop saw, oxy-acetylene torch, electric arc cut rod and plasma torch. Two grinding tools were also evaluated. Materials cut were 2-, 3- and 4-in. dia schedule 40, 80 and 180 type 304L stainless steel pipe. Basic studies were done on uncontaminated pipe. Four-inch-diameter sections of schedule 180 type 304L stainless steel pipe with radioactively contaminated internal surfaces were also cut. The experiments controlled important variables including tools, cutting technique, and type and thickness of material. 15 references, 4 figures, 2 tables
International Nuclear Information System (INIS)
Anon.
2000-01-01
The first text deals with a new circular concerning the collect of the medicine radioactive wastes, containing radium. This campaign wants to incite people to let go their radioactive wastes (needles, tubes) in order to suppress any danger. The second text presents a decree of the 31 december 1999, relative to the limitations of noise and external risks resulting from the nuclear facilities exploitation: noise, atmospheric pollution, water pollution, wastes management and fire prevention. (A.L.B.)
Energy Technology Data Exchange (ETDEWEB)
Szelecsenyi, Ferenc; Kovacs, Zoltan [Hungarian Academy of Sciences, Debrecen (Hungary). Cyclotron Application Dept.; Nagatsu, Kotaro; Zhang, Ming-Rong; Suzuki, Kazutosi [National Institute of Radiological Sciences, Chiba (Japan). Molecular Imaging Center
2014-09-01
The potential for production of the medically relevant {sup 64}Cu has been investigated by proton irradiation of highly enriched {sup 67}Zn targets. The excitation function of the {sup 67}Zn(p,α){sup 64}Cu a nuclear reaction was measured by the stacked-foil technique up to 30 MeV. The prediction of the TALYS code was also compared to the measured cross section results. Based on the improved database of the {sup 67}Zn(p,α){sup 64}Cu reaction, thick target yield as a function of energy was also deduced. Production possibility of {sup 64}Cu is discussed in detail, employing different energy proton beams and with regards to the {sup 61}Cu and {sup 67}Cu contamination levels as a function of the target enrichment level. By using 1 μA beam intensity, 6.3505 h irradiation time and enriched {sup 67}Zn target ({sup 64}Zn ≤ 0.5%, {sup 66}Zn ≤ 9%, {sup 67}Zn ≥ 80%, {sup 68}Zn ≤ 10% and {sup 70}Zn ≤ 0.5%), the expected EOB (End Of bombardment) yields are 43.66, 88.80 and 156.14MBq/μA at 12, 15 and 18 MeV proton energies, respectively. Application time-frames were also deduced where the total radio-copper contamination level remains below 1%. (orig.)
Hilgers, K; Coenen, H H; Qaim, S M
2005-01-01
For production of the therapy related Auger electron emitting neutron deficient nuclide /sup 140/Nd (T/sub fraction 1/2/=3.37d) two routes were investigated: the nuclear reaction range from 15 to 36 MeV and the reaction /sup 141/Pr(p,2n)/sup 140isotopes, namely /sup 139/Nd and /sup 141/Nd, as well as to cerium(IV)-oxide and praseodymium (III)-oxide were obtained by sedimentation and the conventional stacked-foil technique was used for cross section measurements. All the experimental data obtained in this work were compared with the results of theoretical calculations using the exciton model code ALICE-IPPE as well as with literature experimental data, if available. In general, good agreement between experimental and theoretical results was found. The theoretical thick target yields of all the product nuclides were calculated from the measured excitation functions. The theoretical thick target yield of amounts to 12 MBq/mu Acenterdoth and over the energy range E/sub p/=30rightward arrow15 Me V to 210 MBq/mu; A...
International Nuclear Information System (INIS)
Heinz, U.
1988-11-01
I give an overview of the processes determining the shape of energy spectra of hadrons emitted in relativistic nuclear collisions, and discuss how one can extract from them information on the presence of collective transverse flow and on the transition to quark-gluon matter in such collisions. 6 refs., 3 figs
International Nuclear Information System (INIS)
Boudjema, F.; Djouadi, A.; Kneur, J.L.
1992-01-01
The production of excited fermions with mass above 100 GeV is considered. f→Vf (1) decay widths are calculated where V=γ, Z or W. Excited fermion pair production in e + e - annihilation and in γγ collisions, and single production in e + e - annihilation, eγ and γγ collisions is also discussed. Cross sections are calculated for all these cases. The discovery potential of the NLC at 500 GeV is compared with that of other colliders. (K.A.) 15 refs., 5 figs., 2 tabs
Energy Technology Data Exchange (ETDEWEB)
Koch, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1959-12-15
In the first part is studied the properties of atoms excited by the passage of {alpha} particles through the various rare gases at atmospheric pressure. A spectral analysis of the emitted light showed that certain impurities play an important part in producing the fluorescence, and it has led to the conclusion that the light emission contains at least two components - one very short - lived due to the direct deexcitation of the rare gas, the other relatively slower due to the energy transfers to the impurity. The measurement of the life-time of the excited states has confirmed this foregoing hypothesis, the rapid part of the impulse is extremely short: less than 2,25.10{sup -9} s in the case of xenon; the slower part has a life-time depending directly on the nitrogen concentration, nitrogen being the impurity giving the largest effect in all cases. The study of rare gases under the influence of an electric field has made it possible to show that the amount of light produced by an {alpha} particle can be multiplied (by 60, for example, in a field of 600 V:cm) so that the luminescent efficiency is greater than in the case of INaTI. In the second part the characteristics of the rare gases acting as scintillators is examined, the most important property being the absence of fluorescence saturation when the intensity of the excitation incident on the gas is very large. This, together with the very short time of scintillation has made it possible to study a certain number of nuclear physical applications (heavy particle energy-measurements, kinetic studies on nuclear reactors, neutron spectroscopy). (author) [French] On etudie dans la premiere partie les proprietes des atomes excites par le passage de particules {alpha} dans les differents gaz rares a la pression atmospherique. L'etude spectrale de la lumiere emise a montre que certaines impuretes jouent un role considerable dans la fluorescence et on a ete amene a penser que l'emission de lumiere comporte au moins deux
International Nuclear Information System (INIS)
Drago, J.P.; Borkowski, R.J.; Pike, D.H.; Goldberg, F.F.
1982-07-01
The development of a component reliability data for use in nuclear power plant probabilistic risk assessments and reliabiilty studies is presented in this report. The sources of the data are the in-plant maintenance work request records from a sample of nuclear power plants. This data base is called the In-Plant Reliability Data (IPRD) system. Features of the IPRD system are compared with other data sources such as the Licensee Event Report system, the Nuclear Plant Reliability Data system, and IEEE Standard 500. Generic descriptions of nuclear power plant systems formulated for IPRD are given
International Nuclear Information System (INIS)
Gilbert, C.
2006-01-01
During the year 2005, scientists discussed and exchanged their point of view on the forecast of the nuclear wastes. Then a seminar took place during summer 2005 on the ''contribution to the debate on the nuclear wastes management future''. This synthesis aims to present the exchanges of this seminar, grouped around 8 main questions: Have the spent fuel to be reprocessing? Is the geological disposal imperative? The reversibility? The transmutation? Is ''the open research'' on wastes, a necessity, an alibi or a problem? The public anxiety or the anxiety of the public? Can we debate on the nuclear wastes regardless of the nuclear program choice? (A.L.B.)
New results on multiple excitations of giant resonances
International Nuclear Information System (INIS)
Mordechai, S.; Texas Univ., Austin, TX; Moore, C.F.
1993-01-01
Exotic excitations like the double giant dipole were predicted for many years but not observed experimentally until recently. Several experiments have been carried out at Los Alamos National laboratory to search for these new collective modes of the nucleus. The results discover two previously unobserved types of double giant resonances. This work presents the recent pion double charge exchange data and the analysis that support the existence of two such exotic vibrational nuclear modes
Directory of Open Access Journals (Sweden)
Clément E.
2013-12-01
Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N = 60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.
Excitation of Nucleon Resonances
International Nuclear Information System (INIS)
Burkert, Volker D.
2001-01-01
I discuss developments in the area of nucleon resonance excitation, both necessary and feasible, that would put our understanding of nucleon structure in the regime of strong QCD on a qualitatively new level. They involve the collection of high quality data in various channels, a more rigorous approach in the search for ''missing'' resonances, an effort to compute some critical quantities in nucleon resonance excitations from first principles, i.e. QCD, and a proposal focused to obtain an understanding of a fundamental quantity in nucleon structure
International Nuclear Information System (INIS)
2002-11-01
Based on the interest in decommissioning costs within Member States, especially in WWER- 440 operating countries that face the complex decision about continued operation vs. decommissioning in the near future, the IAEA launched the task to prepare a technical document on decommissioning costs of WWER-440 nuclear power plants. The main objectives of this publication were to present the decommissioning costs of WWER-440 NPPs in a uniform manner, i.e. using the cost item and cost group system of the Interim Technical Document on Nuclear Decommissioning 'A Proposed Standardised List of Items for Costing Purposes' developed jointly by the EC, the IAEA and the OECD Nuclear Energy Agency (NEA), and providing, as such, a basis for understanding decommissioning costs differences. Member States operating WWER-440 NPPs or having such units under shutdown or even under decommissioning conditions have been requested to provide cost estimates and other input data in order to facilitate understanding of their cost figures. Both decommissioning options, i.e. immediate decommissioning and safe enclosure, have been considered. In the aforementioned joint Interim Technical Document, cost items related to activities that are carried out with a similar emphasis, whether or not tied to a similar time schedule for decommissioning, or that are based on overall activities that cannot be categorised in a specific time period, are grouped as follows: pre-decommissioning actions; facility shutdown activities; procurement of general equipment and material; dismantling activities; waste processing, storage and disposal; site security, surveillance and maintenance; site restoration, cleanup and landscaping; project management, engineering and site support; research and development; fuel and nuclear material; other costs. Before starting implementation of the study, agreement was obtained on general financial, technical and social boundary conditions that should be used in order to facilitate
International Nuclear Information System (INIS)
Klein, A.
1989-01-01
This paper discusses the following topics: Large amplitude collective motion; Boson mappings of shell model algebras; Semiclassical approximations, TDHF, and heavy ion scattering; New approach to effective interactions; and Bound states in quantum electrodynamics
International Nuclear Information System (INIS)
Kotthaus, Tanja
2010-01-01
In this thesis five heavy deformed isotopes from the mass region A≥230, namely 234 U, 233 U, 231 Th, 230 Pa and 232 Pa, were investigated by means of deuteron-induced neutron transfer reactions. The even-even isotope 234 U has been studied with the 4π-γ-spectrometer MINIBALL at the Cologne Tandem accelerator. Excited nuclei in the isotope 234 U were produced using the reaction 235 U(d,t) at a beam energy of 11 MeV. The target thickness was 3.5 mg/cm 2 . The analysis of the γγ-coincidence data yielded a reinterpretation of the level scheme in 12 cases. Considering its decay characteristics, the 4 + state at an excitation energy of 1886.7 keV is a potential candidate for a two-phonon vibrational state. The isotopes 233 U, 231 Th, 230 Pa and 232 Pa were investigated at the Munich Q3D spectrometer. For each isotope an angular distribution with angles between 5 and 45 were measured. In all four cases the energy of the polarized deuteron beam (vector polarization of 80%) was 22 MeV. As targets 234 U (160 μg/cm 2 ), 230 Th (140 μg/cm 2 ) and 231 Pa (140 μg/cm 2 ) were used. The experimental angular distributions were compared to results of DWBA calculations. For the odd isotope 233 U spin and parity for 33 states are assigned and in the other odd isotope 231 Th 22 assignments are made. The excitation spectra of the two odd-odd isotopes 230 Pa and 232 Pa were investigated for the first time. For the isotope 230 Pa 63 states below an excitation energy of 1.5 MeV are identified. Based on the new experimental data the Nilsson configuration of the ground state is either 1/2[530] p -5/2[633] n or 1/2[530] p +3/2[631] n . In addition 12 rotational bands are proposed and from this six values for the GM splitting energy are deduced as well as two new values for the Newby shift. In the other odd-odd isotope 232 Pa 40 states below an excitation energy of 850 keV are observed and suggestions for the groundstate band and its GM partner are made. From this one GM splitting
The determination of 99Tc by ICP-MS in samples collected near nuclear installations
International Nuclear Information System (INIS)
Ihsanullah; East, B.W.
1991-01-01
99 Tc occurs naturally in the earth's crust primarily from spontaneous fission of 238 U and slow neutron-induced fission of 235 U. 99 Tc is also produced from nuclear detonation tests, nuclear fuel processing plants and nuclear power stations. By comparison to other sources, the contribution to 99 Tc from natural sources and use of 99m Tc in medicine is considered to be negligible. Releases of 99 Tc from the nuclear fuel cycle include reactor operation, nuclear fuel reprocessing, UF 6 conversion, uranium enrichment, U fuel fabrication, high-level waste solidification, low and high-level waste disposal; however the main contribution to the release of 99 Tc is the process of uranium enrichment. Various environmental samples from the Irish Sea and from Chernobyl have been analysed for 99 Tc by newly developed procedures using the inductively coupled plasma mass spectrometry technique. (author)
Nuclear Collective Hamiltonian and Deformations; Yadernyj kollektivnyj gamil'tonian i deformatsii
Energy Technology Data Exchange (ETDEWEB)
Kumar, Krishna [Niels Bohr Institute, University of Copenhagen, Copenhagen (Denmark)
1968-12-15
The scope and limitations of a recently developed treatment of collective quadrupole motion of even-even nuclei are reviewed. This method is based on Bohr's collective Hamiltonian and the pairing-plus-quadrupole model. With an exact, numerical treatment of the couplings between the five components of quadrupole motion, the theory is able to explain and predict many trends in the low-lying levels and electromagnetic moments of nuclei in the W-Os-Pt region. The zero-point quantal motion plays an important role in spreading the nuclear wave-function in the {beta}-{gamma} plane so that the nucleus is affected essentially by the behaviour of the collective Hamiltonian away from the equilibrium shape. The {gamma} -dependence of the Hamiltonian, especially the prolate-oblate difference term of the potential function, plays a crucial role in the splitting of the 2'{sup +} and 4{sup +} states and the non-zero quadrupole moments of I {ne} 0 states, which can occur even if the equilibrium shape is spherical or completely asymmetric with {gamma} = 30 Degree-Sign . The anharmonicities of the six inertial functions of Bohr's Hamiltonian cause {beta}-{gamma} band-mixing in the W isotopes, reduce the ground-{beta}-{gamma} band-mixing in the Os isotopes, and counteract the prolate-oblate difference term so that the spectrum of the calculated {sup 196}Pt appears to be vibrational. The calculation for {sup 196}Pt gives a large, oblate quadrupole moment of the first 2{sup +} state as well as a small cross-over transition from the ground state to the second 2{sup +} state. However, the calculated 2+ states of {sup 192-196}Pt are too high by 0.1-0.2 MeV, and the calculated B(E2; 2{yields}2') values for the region are too large by about a factor of two. Some possible ways of improvement are indicated. (author) [Russian] Rassmatrivajutsja vozmozhnosti i ogranichenija nedavno razvitoj traktovki kollektivnogo kvadrupol'nogo dvizhenija v chetno-chetnyh jadrah. Jetot metod osnovan na
Energy Technology Data Exchange (ETDEWEB)
Régis, J.-M., E-mail: regis@ikp.uni-koeln.de [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Mach, H. [Departamento de Física Atómica y Nuclear, Universidad Complutense, 28040 Madrid (Spain); Simpson, G.S. [Laboratoire de Physique Subatomique et de Cosmologie Grenoble, 53, rue des Martyrs, 38026 Grenoble Cedex (France); Jolie, J.; Pascovici, G.; Saed-Samii, N.; Warr, N. [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Bruce, A. [School of Computing, Engineering and Mathematics, University of Brighton, Lewes Road, Brighton BN2 4GJ (United Kingdom); Degenkolb, J. [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Fraile, L.M. [Departamento de Física Atómica y Nuclear, Universidad Complutense, 28040 Madrid (Spain); Fransen, C. [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Ghita, D.G. [Horia Hulubei National Institute for Physics and Nuclear Engineering, 77125 Bucharest (Romania); and others
2013-10-21
A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ–γ coincidences using an array equipped with N∈N equally shaped very fast high-resolution LaBr{sub 3}(Ce) scintillator detectors is presented. Analogous to the mirror symmetric centroid difference method, the generalized centroid difference method provides two independent “start” and “stop” time spectra obtained by a superposition of the N(N−1)γ–γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ–γ cascade. Provided that the energy response and the electronic time pick-off of the detectors are almost equal, a mean prompt response difference between start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing arrays mean γ–γ time-walk characteristics can be determined for 40keV
International Nuclear Information System (INIS)
Mukhopadhyay, N.C.
1986-01-01
The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested
Energy Technology Data Exchange (ETDEWEB)
Mukhopadhyay, N.C.
1986-01-01
The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)
The big interview - Fukushima: 'Collectively, the international nuclear security system has failed'
International Nuclear Information System (INIS)
Niel, J.C.; Seillan, Hubert
2011-01-01
In an interview the ASN (the French Nuclear Safety Authority) manager summarizes his professional career, describes the ASN missions and outlines the independence of this institution as it is defined and practically exists, gives his opinion and analysis on the Fukushima accident, evokes the meaning of stress tests, discusses the information obtained through inspections of the French nuclear power plants, evokes the desirable evolutions at the international level, explains why terrorism has not been integrated in the stress test procedure, comments the implications of the European level on French safety studies. Some actors are briefly presented: the CEA, AREVA, EDF, the World association of nuclear operators (WANO)
International Nuclear Information System (INIS)
1997-01-01
Since what follows is the final report that the author will ever submit to DOE, it seems appropriate to him that it should be a long-term review, since he has received support from DOE and its predecessor agencies since 1957. The report also contains some material from the earliest years of his career. The next three sections contain an account of what the author thinks he has accomplished in the areas of quantum electrodynamics, nuclear forces, meson pair theory, low energy theory, lie algebra, many body theory, and many more physics topic. There follows a bibliography, consistently referred to in the previous sections and a Curriculum vitae for completeness
International Nuclear Information System (INIS)
Tashjian, B.M.; Logan, B.W.
1983-07-01
Southwest Research Institute (SwRI) is pleased to submit to Sandia National Laboratories this technical report as fulfillment of Task 5 of the proposal entitled A Feasibility Study for Adding a Duty Cycle Data Collection System to the Nuclear Plant Reliability Data System. The purpose of this report is to summarize the work as delineated in the proposal tasks and to recommend follow-on activities. Technical support for this work was provided by Duke Power Company (Duke), subcontractor to SwRI. The four tasks to be performed in conjunction with the Duty Cycle Data Collection Study (renamed in this report Demand Data Collection) were: define component population and measurable parameters; develop data collection and assessment methodologies; assess the impact on utilities; and assess the impact on NPRDS
International Nuclear Information System (INIS)
2015-04-01
The Conference deals with problems of nuclear safety, radiation protection and monitoring of the environment, radiation therapy, separation of radioisotopes, and operation of accelerator radiation centre. Eight contributions were published.
International Nuclear Information System (INIS)
Vishnevs'kij, Yi.M.; Ostashko, V.V.
1995-01-01
The proceeding contain contributed papers submitted to the annual Scientific conference of the Institute for Nuclear Research, Ukraine (kiev, January 1996). The proceedings include reports have been presented on the following sections: Nuclear physics, Solid State physics, Plasma physics, Radio ecology, Reactor safety, Radiation and reactor materials Study. The book is a direct reproduction of the print-ready manuscripts presented by the authors. No corrections have been made in the texts
International Nuclear Information System (INIS)
1983-02-01
There is a wide spectrum of safety significance in the events that can occur during nuclear power plant operations. It is important that lessons be learned from safety-related events (hereinafter referred to as unusual events) so as to improve the safety of nuclear power plants. Hence formal procedures should be established for this purpose. The purpose of this document is to provide guidance to Member States for establishing a system (hereinafter referred to as a national system) for collecting, storing, retrieving, assessing and disseminating information on unusual events in nuclear power plants. The guidance given is based on experience gained in the use of existing national and international systems. This guide covers a national system that is part of a programme to improve nuclear power plant safety using experience gained from operating plants both within and outside the country. Implementing the recommendations in this guide would render any national system compatible with other national systems and facilitate the participation in the IAEA System for Reporting Unusual Events with Safety Significance (hereinafter referred to as the IAEA Incident Reporting System, IAEA-IRS) for more widespread dissemination of lessons learned from nuclear power plant operation
Directory of Open Access Journals (Sweden)
Manen Jean-François
2004-11-01
Full Text Available Abstract Background Intra-specific and intra-individual polymorphism is frequently observed in nuclear markers of Ilex (Aquifoliaceae and discrepancy between plastid and nuclear phylogenies is the rule in this genus. These observations suggest that inter-specific plastid or/and nuclear introgression played an important role in the process of evolution of Ilex. With the aim of a precise understanding of the evolution of this genus, two distantly related sympatric species collected in Tenerife (Canary Islands, I. perado and I. canariensis, were studied in detail. Introgression between these two species was previously never reported. One plastid marker (the atpB-rbcL spacer and two nuclear markers, the ribosomal internal transcribed spacer (ITS and the nuclear encoded plastid glutamine synthetase (nepGS were analyzed for 13 and 27 individuals of I. perado and I. canariensis, respectively. Results The plastid marker is intra-specifically constant and correlated with species identity. On the other hand, whereas the nuclear markers are conserved in I. perado, they are highly polymorphic in I. canariensis. The presence of pseudogenes and recombination in ITS sequences of I. canariensis explain this polymorphism. Ancestral sequence polymorphism with incomplete lineage sorting, or past or recent hybridization with an unknown species could explain this polymorphism, not resolved by concerted evolution. However, as already reported for many other plants, past or recent introgression of an alien genotype seem the most probable explanation for such a tremendous polymorphism. Conclusions Data do not allow the determination with certitude of the putative species introgressing I. canariensis, but I. perado is suspected. The introgression would be unilateral, with I. perado as the male donor, and the paternal sequences would be rapidly converted in highly divergent and consequently unidentifiable pseudogenes. At least, this study allows the establishment of
Kiaalhosseini, Saeed
In modern contaminant hydrology, management of contaminated sites requires a holistic characterization of subsurface conditions. Delineation of contaminant distribution in all phases (i.e., aqueous, non-aqueous liquid, sorbed, and gas), as well as associated biogeochemical processes in a complex heterogeneous subsurface, is central to selecting effective remedies. Arguably, a factor contributing to the lack of success of managing contaminated sites effectively has been the limitations of site characterization methods that rely on monitoring wells and grab sediment samples. The overarching objective of this research is to advance a set of third-generation (3G) site characterization methods to overcome shortcomings of current site characterization techniques. 3G methods include 1) cryogenic core collection (C3) from unconsolidated geological subsurface to improve recovery of sediments and preserving key attributes, 2) high-throughput analysis (HTA) of frozen core in the laboratory to provide high-resolution, depth discrete data of subsurface conditions and processes, 3) resolution of non-aqueous phase liquid (NAPL) distribution within the porous media using a nuclear magnetic resonance (NMR) method, and 4) application of a complex resistivity method to track NAPL depletion in shallow geological formation over time. A series of controlled experiments were conducted to develop the C 3 tools and methods. The critical aspects of C3 are downhole circulation of liquid nitrogen via a cooling system, the strategic use of thermal insulation to focus cooling into the core, and the use of back pressure to optimize cooling. The C3 methods were applied at two contaminated sites: 1) F.E. Warren (FEW) Air Force Base near Cheyenne, WY and 2) a former refinery in the western U.S. The results indicated that the rate of core collection using the C3 methods is on the order of 30 foot/day. The C3 methods also improve core recovery and limits potential biases associated with flowing sands
Di Donato, Guido; Laufer-Amorim, Renée; Palmieri, Chiara
2017-10-01
Ten normal prostates, 22 benign prostatic hyperplasia (BPH) and 29 prostate cancer (PC) were morphometrically analyzed with regard to mean nuclear area (MNA), mean nuclear perimeter (MNP), mean nuclear diameter (MND), coefficient of variation of the nuclear area (NACV), mean nuclear diameter maximum (MDx), mean nuclear diameter minimum (MDm), mean nuclear form ellipse (MNFe) and form factor (FF). The relationship between nuclear morphometric parameters and histological type, Gleason score, methods of sample collection, presence of metastases and survival time of canine PC were also investigated. Overall, nuclei from neoplastic cells were larger, with greater variation in nuclear size and shape compared to normal and hyperplastic cells. Significant differences were found between more (small acinar/ductal) and less (cribriform, solid) differentiated PCs with regard to FF (pnuclear morphometric analysis in combination with Gleason score can help in canine prostate cancer grading, thus contributing to the establishment of a more precise prognosis and patient's management. Copyright © 2017 Elsevier Ltd. All rights reserved.
Butler, P; Voulot, D; Rahkila, P J; Darby, I G; Grahn, T; Bree, N C F; Julin, R J; Diriken, J V J; Jenkins, D G; Kroell, T; Huyse, M L
In regions near magic nuclei, seniority can be regarded as a good quantum number. In the N = 122 isotones above the Z = 82 shell closure relative high-$\\textit{j}\\,$ single-particle proton orbitals dominate the structure and thus levels up to $\\textit{I}$ = 2$\\textit{j}$ - 1 could, in principle, be understood within the seniority scheme. While B(E2) values usually increase within the band with increasing $\\textit{I}$, the seniority scheme can lead to a contrasting result. The present proposal addresses this phenomenon through the measurements of previously unknown B(E2; 0$^{+}\\rightarrow$ 2$^{+}$) values in $^{206}$Po and $^{208}$Rn. The proposed Coulomb excitation measurements of radioactive beams will be carried out at the REX-ISOLDE facility using the MINIBALL $\\gamma$-ray spectrometer.
Collective statement on major nuclear safety research facilities and programmes at risk
International Nuclear Information System (INIS)
2001-01-01
Nuclear safety research remains necessary, since nuclear power programmes are dynamic. In addition to maintaining in-depth competencies, its aim is to provide information to plant designers, operators and regulators in support of the resolution of safety issues, to strengthen confidence in their solution and their implementation, and also to anticipate problems of potential significance. New fields of research open up as a result of plant ageing, plant life extension, plant up-rating, optimisation of plant economics and the associated need to further reduce uncertainties in safety margins quantification. The safety evaluation of future reactor systems being developed or considered in several Member countries also requires new research efforts. Accordingly, Member countries are encouraged to support efforts to maintain key research data, facilities and programmes through national support of international co-operation and funding. This should be under-pinned by development of short-, medium- and long-term strategic visions of the needs of the nuclear safety research community, including a strong component of international collaboration given the international nature of nuclear safety issues. (author)
International Nuclear Information System (INIS)
Mendez, U.; Tenorio C, D.; Ruvalcaba, J.L.; Lopez, J.A.
2005-01-01
The main objective of this investigation was to determine the composition and microstructure of 13 metallic devices by means of the nuclear techniques of PIXE, RBS and conventional; which were elaborated starting from copper and gold, and they were in the offering of a tarasc personage located in the 'Matamoros' porch in Uruapan, Michoacan, Mexico. (Author)
International Nuclear Information System (INIS)
Liran, S.; Technion-Israel Inst. of Tech., Haifa. Dept. of Physics)
1977-01-01
This paper extends the recent theory of Liran, Scheefer, Scheid and Greiner on non-adiabatic cranking and nuclear collective motion. In the present work we show the self-consistency conditions for the collective motion, which are indicated by appropriate time-dependent Lagrange multipliers, can be treated explicitly. The energy conservation and the self-consistency condition in the case of one collective degree of freedom are expressed in differential form. This leads to a set of coupled differential equations in time for the many-body wave function, for the collective variable and for the Lagrange multiplier. An iteration procedure similar to that of the previous work is also presented. As an illustrative example, we investigate Brink's single-particle description of the giant-dipole resonance. In this case, the important role played by non-adiabaticity and self-consistency in determining the collective motion is demonstrated and discussed. We also consider the fact that in this example of a fast collective motion, the adiabatic cranking model of Inglis gives the correct mass parameter. (orig.) [de
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-07-01
The Japan Nuclear Cycle Development Institute (JNC) initiated a system to promote the public collection type researches of nuclear fuel cycle since 1999, in order to intend to promote collaboration with universities and research institutes. The system aims to intend to activate researching environment in JNC by intercourse, information exchange, publication of results and so on between researchers in and out of JNC, effectively to proceed basic and fundamental R and D. Here were outlined on eleven researching theme, such as upgrading of velocity and temperature measurement of non-contact type fluid by using electromagnetic ultrasonic wave, development of temperature history memory elements for radiation environment test of a fast breeder reactor, direct glassification of salt wastes by using oxygen plasma, a method on dissolving extraction of metal oxides by using a super-critical fluid, creation of highly separable materials by assistance of computational chemistry (aiming at high order processing of high level radioactive wastes), and so on. (G.K.)
International Nuclear Information System (INIS)
2000-07-01
The Japan Nuclear Cycle Development Institute (JNC) initiated a system to promote the public collection type researches of nuclear fuel cycle since 1999, in order to intend to promote collaboration with universities and research institutes. The system aims to intend to activate researching environment in JNC by intercourse, information exchange, publication of results and so on between researchers in and out of JNC, effectively to proceed basic and fundamental R and D. Here were outlined on eleven researching theme, such as upgrading of velocity and temperature measurement of non-contact type fluid by using electromagnetic ultrasonic wave, development of temperature history memory elements for radiation environment test of a fast breeder reactor, direct glassification of salt wastes by using oxygen plasma, a method on dissolving extraction of metal oxides by using a super-critical fluid, creation of highly separable materials by assistance of computational chemistry (aiming at high order processing of high level radioactive wastes), and so on. (G.K.)
International Nuclear Information System (INIS)
Bendarag, A.
1999-01-01
In this work we study the collective phenomena in the central collisions of heavy ions for the Au + Au, Xe + CsI and Ni + Ni systems at incident energies from 150 to 400 MeV/nucleon with the data of the FOPI detector. In order to describe completely the flow of the nuclear matter, we fit the double differential momentum distributions with two-dimensional Gaussian. We study the characteristic parameters of the collective flow (flow range, aspect ratios, flow parameter) versus the charge and the mass of the fragments as well as the incident energy and the centrality of the collisions. The transverse energy is used for selecting the central collisions. The method of the Gaussian fits requires also to reconstruct the reaction plane of the event. Then we correct the parameters for the finite number of particles effects and account for the influence of the acceptance of the detector. We confirm the importance of the thermal motion for the light charge or mass fragments and, conversely, the predominance of the collective motion for the heavy fragments. A common flow angle for all the types of particles is highlighted for the first time, demonstrating the power of the method of the Gaussian fits; The evolution of the other parameters confirms the observations done with other methods of flow analysis. These results should contribute to put constraints on the collision models and to enlarge our knowledge of the properties of the nuclear matter. (author)
Microscopic calculations of nuclear matter collective flow in Nb(400 MeV/N) + Nb
International Nuclear Information System (INIS)
Hoffer, J.B.; Kruse, H.; Molitoris, J.J.; Stoecker, H.
1984-01-01
The recent experimental observation of sidewards peaks in the emission pattern of fragments emitted in collisions of heavy nuclear systems has stimulated a dispute among theorists about how to interpret these data. It has been shown that the observations are in agreement with the results of macroscopic nuclear fluid dynamical calculations, but several microscopic calculations done to simulate the sidewards emission (via the intranuclear cascade (INC) approach) failed - the angular distributions obtained where always forward peaked. A many body equations of motion (EOM) approach to study heavy ion collision has been developed. The approach is analogous to the early work of Bodmer et al., and Wilets et al. Hamilton's equations of motion are solved for an ensemble of nucleons with simultaneous mutual two-body interactions between all particles. The model predicts the sidewards emission peaks for the Nb + Nb reaction
International Nuclear Information System (INIS)
Lamarre, D.; Waller, A.
1980-01-01
The principle of dosimetry management chosen by Fessenheim nuclear power station was originally consisted of two phases: - an automatic acquisition of individual doses realized by stylodosimeter readers; - a deferred data processing by computer. The whole system has not been used during the shutdown for the first refuelling of unit number one in view of encountered difficulties with perfecting of automatic readers prototype, this last phase has been replaced by a manual acquisition of doses. The dosimetry data processing has two main objects: - supervision of individual dosimetry for people who work in the nuclear power station; - knowledge of doses assigned for each working and equipment. Moreover, a first dosimetric result of the shutdown for refuelling of unit number one, enables to notice the workings which doses are the most important and written in percentage of total doses: regulatory controls: about 19%; - steam generators working: 16%; - working decontamination and making health physics screen (lock chamber) 10% [fr
Nuclear collective motion within the O(N-1) invariant dynamics
International Nuclear Information System (INIS)
Cerkaski, M.; Mikhailov, I.N.
1990-08-01
Assuming the O(N-1) symmetry for the interaction term in the N-body Hamiltonian we find a closed subsystem of equations describing the collective motion in a classical way. Within the model, the nucleons move along trajectories determined by a one-body time-dependent harmonic potential depending on the collective variables. The relation of the equations for the collective motion to the system of equations found elsewhere for the second order moments of the Wigner distribution function is discussed. The problem of finding stationary solutions to the collective equations of motion leads to the cranking model with the selfconsistency relations depending on the O(N-1) scalar part of the potential. 52 refs. (author)
Effective interactions and elementary excitations in quantum liquids
International Nuclear Information System (INIS)
Pines, D.
1986-01-01
The effective interactions which provide a wavevector and frequency dependent restoring force for collective modes in quantum liquids are derived for the helium liquids by means of physical arguments and sum rule and continuity considerations. A simple model is used to take into account mode-mode coupling between collective and multiparticle excitations, and the results for the zero-temperature liquid 4 He phonon-maxon-roton spectrum are shown to compare favorably with experiment and with microscopic calculation. The role played by spin-dependent backflow in liquid 3 He is analyzed, and a physical interpretation of its variation with density and spin-polarization is presented. A progress report is given on recent work on effective interactions and elementary excitations in nuclear matter, with particular attention to features encountered in the latter system which have no counterparts in the helium liquids
Collective occupational dose for nuclear reactors of the 2., 3. and 4. generation
International Nuclear Information System (INIS)
Guidez, J.; Saturnin, A.
2016-01-01
In France during reactor operation the individual occupational doses are collected and recorded according to the law. When you sum up all the individual doses you get the yearly collective dose expressed in Man.Sv/year. This piece of information can be used to make comparisons between various types of reactors and between reactors of the same type. The results show a steady decrease of the collective dose for all types of reactors over the time except for CANDU reactors for which a slight increase of the dose has appeared since the years 1996-1998. The decrease is due to the continuous improvement of reactor operating and to changes in the reactor design. There is also a constant gap over time between the collective dose for a BWR reactor (1.12 Man.Sv/y) and a PWR reactor 0.60 Man.Sv/y), this gap is certainly due to N 16 nuclide that is created in the primary circuit and transported to turbines in the case of a BWR reactor. For sodium-cooled fast reactors (RNR-Na) the collective dose is below 0.40 Man.Sv/y except for the BN-600 reactor. (A.C.)
International Nuclear Information System (INIS)
Jones, S R; Lambers, B; Stevens, A
2004-01-01
Collective dose has long been advocated as an important measure of the detriment associated with practices that involve the use of radioactivity. Application of collective dose in the context of worker protection is relatively straightforward, whereas its application in the context of discharges to the environment can yield radically different conclusions depending upon the population groups and integration times that are considered. The computer program PC-CREAM98 has been used to provide an indicative disaggregation into individual dose bands of the collective dose due to potential future radioactive discharges from the nuclear fuel reprocessing site at Sellafield in the UK. Two alternative discharge scenarios are considered, which represent a 'stop reprocessing early, minimum discharge' scenario and a 'reprocessing beyond current contracts' scenario. For aerial discharges, collective dose at individual effective dose rates exceeding 0.015 μSv y -1 is only incurred within the UK, and at effective dose rates exceeding 1.5 μSv y -1 is only incurred within about 20 km of Sellafield. The geographical distribution of collective dose from liquid discharges is harder to assess, but it appears that collective dose incurred outside the UK is at levels of individual effective dose rate below 1.5 μSv y -1 , with the majority being incurred at rates of 0.002 μSv y -1 or less. In multi-attribute utility analyses, the view taken on the radiological detriment to be attributed to the two discharge scenarios will depend critically on the weight or monetary value ascribed to collective doses incurred within the differing bands of individual dose rate
International Nuclear Information System (INIS)
Cesari, F.G.; Terzi, L.A.; Giostri, A.; Bernini, C.; Sirito, E.; Sirito, M.
2005-01-01
The Caorso's Nuclear Power Plant (BWR, 870 MWe) has just started the decommissioning process, with the intent to reach, by almost ten years, the 'green field' conditions for the site. The plant has fully worked for a very short period of time, by 1981 to 1986, being shut down after 1987 Italy's poll that abrogated nuclear power use. The dismantling of the components and of the structural materials has already begun in the Turbine Building. The University of Bologna, on indication of the NPP's management, has started an experimental campaign to test the cutting processes and its filtering plant. The starting phase is the qualification of the cutting methods chosen by Caorso's management, oxyfuel and plasma cuttings. This campaign is set over no contaminated material, or, better, material with a contamination under the level of free release, and is now running in the University Labs. Next phase are filtering tests. This part of the qualifying campaign is set to highlight the kind of trouble that can emerge in the cutting processes, not yet taking into account radioactivity. Caorso's BWR is a plant designed and built in the 70s. Possible decommissioning problems weren't considered during the design phase so the cutting processes will be quite difficult, even on the conventional side. The final phase is settled in the plant. Cutting tests, following indications made by previous campaigns, will be conducted in the Turbine Building, where tests can be conducted on a low level of radioactivity (only some little part of it has a contamination level over the free release limit of 1 Bq/cm 2 ). The intent is to develop an extensive cutting procedure, with the obvious option of remote control, able to face difficulties connected with cutting processes in a nuclear plant like Caorso. This means handling with radioactivity and with not airy narrow rooms, fulfilled with pipes. (authors)
A study of collective coordinates and dynamical groups in nuclear theory
International Nuclear Information System (INIS)
Papadopolos, Z.
1983-01-01
Lie-algebraic techniques for the group action on manifolds given as a direct product of coset spaces and group manifolds are developed. The microscopic realisation of the Mass Quadrupole Collective Model (MQC) in the S0(3)xSO(n) and GLsub(+)(3, R)xSO(n) schemes is studied. The problem of the separation of the kinetic energy and the velocity field into a collective and an intrinsic part is analyzed. Different coordinate schemes in phase space for the U(n)-invariant collective motion and the U(3) dynamical group are introduced. In the GL(3,C)xU(n) scheme, the invariant volume element in the new coordinates and a completely orthonormal basis is constructed. (orig.) [de
International Nuclear Information System (INIS)
Insolia, A.
1996-01-01
The EOS Collaborations has completed an exclusive study of relativistic heavy ion collisions at the Bevalac using a variety of projectile, target and beam energy combinations. We report here results on directed sidewards flow in Au+Au between 0.25 AGeV and 1.2 AGeV, using a standard in-plane transverse momentum analysis. We also report on projectile fragmentation of Au in C at 1 AGeV. An analysis of fluctuations and critical exponents for small systems seems to support the idea that the multifragmentation regime is associated with a liquid gas phase transition in nuclear matter. (authors)
Non-equilibrium entropy in excited nuclei
International Nuclear Information System (INIS)
Betak, E.
1991-06-01
The time-dependent behaviour of entropy in excited nuclei is investigated. In distinction to recent claims, it is shown that no self-organization is involved in pre-equilibrium nuclear reactions. (author). 9 refs.; 4 figs
Directory of Open Access Journals (Sweden)
Kanami Nakashima
2015-11-01
Full Text Available It is well known from the experience after the 1986 accident at the Chernobyl Nuclear Power Plant that radiocesium tends to concentrate in wild mushrooms. In this study, we collected wild mushrooms from the Kawauchi Village of Fukushima Prefecture, located within 30 km of the Fukushima Daiichi Nuclear Power Plant, and evaluated their radiocesium concentrations to estimate the risk of internal radiation exposure in local residents. We found that radioactive cesium exceeding 100 Bq/kg was detected in 125 of 154 mushrooms (81.2%. We calculated committed effective doses based on 6,278 g per year (age > 20 years, 17.2 g/day, the average intake of Japanese citizens, ranging from doses of 0.11–1.60 mSv, respectively. Although committed effective doses are limited even if residents eat contaminated foods several times, we believe that comprehensive risk-communication based on the results of the radiocesium measurements of food, water, and soil is necessary for the recovery of Fukushima after this nuclear disaster.
Process to produce excited states of atomic nuclei
International Nuclear Information System (INIS)
Morita, M.; Morita, R.
The claims of a patented process which relates to the production of excited states of atomic nuclei are outlined. Among these are (1) production of nuclear excited states by bombarding the atoms with x rays or electrons under given conditions, (2) production of radioactive substances by nuclear excitation with x rays or electrons, (3) separation of specific isotopes from a mixture of isotopes of the same element by means of nuclear excitation followed by chemical treatment. The invention allows production of excited states of atomic nuclei in a relatively simple manner without the need of large apparatus and equipment
International Nuclear Information System (INIS)
Hofmann, H.
1997-01-01
A transport theory is developed for collective motion of systems such as an atomic nucleus, which may be considered as a typical representative of a self-bound micro-system. Albeit for pragmatic reasons, collective variables are introduced as shape parameters, self-consistency with respect to the nucleonic degrees of freedom has been implemented at various important stages. This feature leads to subsidiary conditions which are obeyed locally for both the average motion as well as for the quantized Hamiltonian constructed through a Bohm-Pines procedure. Furthermore, self-consistency governs the definition of the transport coefficients appearing in the equations for collective motion. The latter is associated to the time evolution of the density in collective phase space, for which the concept of the Wigner function is employed. Global motion is described by propagating the system in successive time laps which are macroscopically small, but microscopically large. This enables one to exploit linearization procedures and to take advantage of the benefits of linear response theory. A microscopic damping mechanism is introduced by dressing the energies of the independent particle model by complex self-energies, the parameters of which are determined from optical model considerations. Numerical evaluations of transport coefficients are described and tested for the case of fission in the light of recent experimental findings. The theory allows one to extend both Kramers' picture of this process as well as his equation for the density distribution into the quantum regime. (orig.)
Selective Coherent Excitation of Charged Density Waves
Tsvetkov, A.A.; Sagar, D.M.; Loosdrecht, P.H.M. van; Marel, D. van der
2003-01-01
Real time femtosecond pump-probe spectroscopy is used to study collective and single particle excitations in the charge density wave state of the quasi-1D metal, blue bronze. Along with the previously observed collective amplitudon excitation, the spectra show several additional coherent features.
Non-unitary boson mapping and its application to nuclear collective motions
International Nuclear Information System (INIS)
Takada, Kenjiro
2001-01-01
First, the general theory of boson mapping for even-number many-fermion systems is surveyed. In order to overcome the confusion concerning the so-called unphysical or spurious states in the boson mapping, the correct concept of the unphysical states is precisely given in a clear-cut way. Next, a method to apply the boson mapping to a truncated many-fermion Hilbert space consisting of collective phonons is proposed, by putting special emphasis on the Dyson-type non-unitary boson mapping. On the basis of this method, it becomes possible for the first time to apply the Dyson-type boson mapping to analyses of collective motions in realistic nuclei. This method is also extended to be applicable to odd-number-fermion systems. As known well, the Dyson-type boson mapping is a non-unitary transformation and it gives a non-Hermitian boson Hamiltonian. It is not easy (but not impossible) to solve the eigenstates of the non-Hermitian Hamiltonian. A Hermitian treatment of this non-Hermitian eigenvalue problem is discussed and it is shown that this treatment is a very good approximation. using this Hermitian treatment, we can obtain the normal-ordered Holstein-Primakoff-type boson expansion in the multi-collective-phonon subspace. Thereby the convergence of the boson expansion can be tested. Some examples of application of the Dyson-type non-unitary boson mapping to simplified models and realistic nuclei are also shown, and we can see that it is quite useful for analysis of the collective motions in realistic nuclei. In contrast to the above-mentioned ordinary type of boson mapping, which may be called a a 'static' boson mapping, the Dyson-type non-unitary self-consistent-collective-coordinate method is discussed. The latter is, so to speak, a 'dynamical' boson mapping, which is a dynamical extension of the ordinary boson mapping to be capable to include the coupling effects from the non-collective degrees of freedom self-consistently.Thus all of the Dyson-type non-unitary boson
International Nuclear Information System (INIS)
Tolmachyov, S.; Maeda, Y.; Mitarai, S.; Nakashima, T.; Momoshima, N.; Yamamoto, M.
2001-01-01
36 Cl in soil samples from the Semipalatinsk Nuclear Test Site (former USSR) was measured at Kyushu University Tandem Laboratory (KUTL) by accelerator mass spectrometry (AMS) coupled with projectile X-ray detection (PXD) technique. The separation of competing 36 S and 3 6Cl atomic isobars, was satisfactory by PXD technique. Measured 36 Cl/Cl atom ratio was (5.0 ± 0.6) x 10 -10 and an average activity of 36 Cl was calculated as (2.0 ± 0.2) mBq/g, which is in a good agreement with that obtained by liquid scintillation counting (LSC) method previously. Currently developed AMS system at the Kyushu University can be applied for routine 36 Cl analysis at 36 Cl/Cl = 10 -11 atom ratio level. (author)
Precision Mass Measurements of Cr-6358 : Nuclear Collectivity Towards the N =40 Island of Inversion
Mougeot, M.; Atanasov, D.; Blaum, K.; Chrysalidis, K.; Goodacre, T. Day; Fedorov, D.; Fedosseev, V.; George, S.; Herfurth, F.; Holt, J. D.; Lunney, D.; Manea, V.; Marsh, B.; Neidherr, D.; Rosenbusch, M.; Rothe, S.; Schweikhard, L.; Schwenk, A.; Seiffert, C.; Simonis, J.; Stroberg, S. R.; Welker, A.; Wienholtz, F.; Wolf, R. N.; Zuber, K.
2018-06-01
The neutron-rich isotopes Cr 58 - 63 were produced for the first time at the ISOLDE facility and their masses were measured with the ISOLTRAP spectrometer. The new values are up to 300 times more precise than those in the literature and indicate significantly different nuclear structure from the new mass-surface trend. A gradual onset of deformation is found in this proton and neutron midshell region, which is a gateway to the second island of inversion around N =40 . In addition to comparisons with density-functional theory and large-scale shell-model calculations, we present predictions from the valence-space formulation of the ab initio in-medium similarity renormalization group, the first such results for open-shell chromium isotopes.
A guide to archival collections relating to radioactive fallout from nuclear weapon testing
International Nuclear Information System (INIS)
1989-10-01
This guide has been prepared by professional historians who have a working knowledge of many of the record collections, included in the following pages. In describing materials, they have tried to include enough information so that persons unfamiliar with the complexities of large record systems will be able to determine the nature of the information in, and the quality of, each record collection. The guide is organized alphabetically by the means of the record repositories, not by the organizations which have custody of the records. It should be noted that arrangement by location does not reveal at a single glance all of the materials that may have originated in a specific laboratory, research center, or government agency. For example, records originated in one of the Atomic Energy Commission's national laboratories may, in some cases, be listed under the Federal Records Centers to which they have been retired. Thus, this guide includes an index of agencies originating documents and pages listing those agencies
Imitation simulation of collective acquisition systems for nuclear-physical data
International Nuclear Information System (INIS)
Ryabov, Yu.F.; Khomutnikov, V.P.
1981-01-01
The imitation simulation method of collective investigation systems (CIS) oriented to the acquisition and express-processing of experiments performed on the basis of multi-beam research reactors under film data measurements by means of semiautomatic installations is described. The method is based on description of specific requests to the system as service phase sequences (small computer data acquisition, mass transfer in CIS, data bank record processing). The algorithm basis of these phases performed is delay imitation at each of the means employed. The structure of the simulating program is presented. The complex of programs is realized on the base of the NOST program packet for the M-4030 computer. Its efficiency in collective multiprogram systems investigation is shown [ru
The time dependent Hartree-Fock-theory for collective nuclear motions
International Nuclear Information System (INIS)
Goeke, K.
1976-11-01
The time-dependent Hartree-Fock theory (TDHF) approximately solves the Schroedinger equation by a variational method in the space of the time-dependent Slater determinants. As the TDHF wave function, similar to the exact solution has the property of being determined completely for all times by the nucleon-nucleon interaction and by assuming initial conditions. TDHF is expected to describe collective motion of nuclei with large amplitudes, too. The subject of this paper is to formulate the TDHF theory and its adiabatic limiting case (ATDHF) suited for setting up a collective Schroedinger equation, to investigate the relations with other theories, and to show the applicability for solving practical problems. (orig./WL) [de
Microscopic nuclear-dissipation mechanism as damping of collective motion in the second RPA
International Nuclear Information System (INIS)
Yannouleas, C.; Dworzecka, M.; Griffin, J.J.
1982-01-01
A microscopic model for the damping of the one-phonon RPA collective state, absolute value c > = Q/sub c/ 0 > /sub S//sub R/, has been previously described. This one-phonon RPA collective state is defined within a restricted subspace, S/sub R/, of the discrete 1p-1h structure. Its damping is described within an extended subspace, S = S/sub R/ + S/sub A/, by the time evolution of a wave packet according to the RPA and the Second RPA approximations of the complete Schroedinger equation when initialized with the one-phonon state. The one-phonon state, however, is unable to describe time-varying oscillations of the mean field. Such oscillations require wave packets formed by linear superposition of the RPA many-phonon eigenstates. Coherent time-varying oscillations of the mean field (multi-phonon initial states) are discussed
International Nuclear Information System (INIS)
Watabe, Shohei; Ohashi, Yoji; Kato, Yusuke
2011-01-01
We investigate tunneling properties of collective modes in the polar phase of a spin-1 spinor Bose-Einstein condensate (BEC). This spinor BEC state has two kinds of gapless modes (i.e., Bogoliubov and spin-wave). Within the framework of mean-field theory at T=0, we show that these Goldstone modes exhibit perfect transmission in the low-energy limit. Their anomalous tunneling behavior still holds in the presence of superflow, except in the critical current state. In the critical current state, while the tunneling of Bogoliubov mode is accompanied by finite reflection, the spin wave still exhibits perfect transmission, unless the strengths of spin-dependent and spin-independent interactions take the same value. We discuss the relation between perfect transmission of a spin wave and underlying superfluidity through a comparison of wave functions of the spin wave and the condensate.
Microscopic calculations of nuclear structure and nuclear correlations
International Nuclear Information System (INIS)
Wiringa, R.B.
1992-01-01
A major goal in nuclear physics is to understand how nuclear structure comes about from the underlying interactions between nucleons. This requires modelling nuclei as collections of strongly interacting particles. Using realistic nucleon-nucleon potentials, supplemented with consistent three-nucleon potentials and two-body electroweak current operators, variational Monte Carlo methods are used to calculate nuclear ground-state properties, such as the binding energy, electromagnetic form factors, and momentum distributions. Other properties such as excited states and low-energy reactions are also calculable with these methods
Collection, validation, and description of data for the Oak Ridge nuclear industry mortality study
International Nuclear Information System (INIS)
Watkins, J.; Reagan, J.; Cragle, D.; West, C.; Tankersley, W.; Frome, E.; Watson, J.
1992-01-01
In response to the continuing controversy over the long-term health effects of protracted occupational exposure to low levels of ionizing radiation, a mortality study was initiated pooling data for all workers hired before December 31, 1982, and employed for at least 30 days by one of the three DOE facilities in Oak Ridge, Tennessee. Topics of discussion will include issues involving the collection and validation of this large, complex data set and characteristics of demographic and exposure data for the study cohort
Dissolution of aerosol particles collected from nuclear facility plutonium production process
International Nuclear Information System (INIS)
Ning Xu; Martinez, Alex; Schappert, Michael; Montoya, D.P.; Martinez, Patrick; Tandon, Lav
2016-01-01
A simple, robust analytical chemistry method has been developed to dissolve plutonium containing particles in a complex matrix. The aerosol particles collected on Marple cascade impactor substrates were shown to be dissolved completely with an acid mixture of 12 M HNO 3 and 0.1 M HF. A pressurized closed vessel acid digestion technique was utilized to heat the samples at 130 deg C for 16 h to facilitate the digestion. The dissolution efficiency for plutonium particles was 99 %. The resulting particle digestate solution was suitable for trace elemental analysis and isotope composition determination, as well as radiochemistry measurements. (author)
International Nuclear Information System (INIS)
Sotty, C.
2013-01-01
The underlying structure in the region A ∼ 100, N ∼ 60 has been under intensive and extensive investigation, mainly by β-decay and γ-ray spectroscopy from fission processes. Around N ∼ 60, by adding just few neutrons, protons a rapid shape change occurs from spherical-like to well deformed g.s. shape. Shape coexistence has been observed in the Sr and Zr nuclei, and is expected to take place in the whole region. The mechanisms involved in the appearance of the deformation is not well understood. The interplay between down-sloping and up-sloping neutron Nilsson orbital is evoked as one of the main reasons for the sudden shape change. However, a clear identification of the active proton and neutron orbitals was still on-going. For that purpose, the neutron rich 93;95;97;99 Rb isotopes have been studied by Coulomb excitation at CERN (ISOLDE) using the REX-ISOLDE post-accelerator and the MINIBALL setup. The completely unknown structures of 97;99 Rb have been populated and observed. Prompt γ-ray coincidences of low-lying states have been observed and time-correlated in order to build level schemes. The associated transition strengths have been extracted with the GOSIA code. The observed matrix elements of the electromagnetic operator constituted new inputs of further theoretical calculations giving new insight on the involved orbitals. The sensitivity of such experiment can be increased using nuclear spin polarized radioactive ion beam. For that purpose the Tilted Foils Technique (TFT) of polarization has been investigated at CERN. This technique consists to spin polarize the ion beam, passing through thin foils tilted at an oblique angle with respect to the beam direction. The initially obtained atomic polarization is transferred to the nucleus by hyperfine interaction. This technique does not depend on the chemical nature of the element. Short lived nuclei can be polarized in-flight without any need to be stopped in a catcher. It opens up the possibility to
The comparison of bosonic and fermionic descriptions of collective nuclear structure
International Nuclear Information System (INIS)
Baktybaev, K.
2004-01-01
Full text: Bosonic and fermionic descriptions for the nuclear many body system are complementary. The archetypical bosonic algebra is the original interacting boson model [1]. Without distinguishing between proton and neutron bosons, it gave rise to successful phenomenology for medium and heavy nuclei, and is built from the concept of dynamical symmetry whose genesis is a group chain. The fermionic algebra on the other hand, such as the fermion dynamical symmetry model (FDSM) [2], is necessarily more complex because it originates from the shell structure and uses protons and neutrons as building blocks. We have presented two complementary pictures of bosons and fermions to describe the normal and the exotic states. We find that the bosonic concepts of symmetry and mixed- symmetry can subtly be interpreted within the fermion picture as well. However, there is one important dichotomy. In the fermion description, the n-p quadrupole interaction is responsible for splitting these two type of states and produces strong M1 transitions. This phenomenon is in close analogy to the L-S splitting of orbital and spin spaces. The examples given in the paper show that many 2 + normal and exotic states are in fact 'partners' for n-p quadrupole coupling and there fore must split in its presence. We would like to emphasize that the proper placement of the positions of the exotic states and the prediction of their respective transitions must be another stringent constraint on the effective interactions of the Hamiltonian
Direct interaction in nuclear reactions: a theory
International Nuclear Information System (INIS)
Dominicis, C.T. de
1959-01-01
General treatment of the foundations of direct interaction in nuclear reactions; representation of the instantaneous elastic scattering amplitude by the scattering amplitude due to a complex potential; expansion of the instantaneous inelastic scattering amplitude and discussion of the 1. Bohr approximation (distorted waves) contribution to individual and collective states of excitation. (author) [fr
Collective many-body dynamics in the vicinity of nuclear driplines
International Nuclear Information System (INIS)
Volya, Alexander; Zelevinsky, Vladimir
2007-01-01
The Continuum Shell Model is a powerful theoretical tool for analysis of many-body dynamics embedded in the continuum. Here we formulate the method and use an example of a realistic shell model calculation for oxygen isotopes to demonstrate the seamless transition from bound states to resonances and cross sections in continuum within the same framework. The coupled dynamics of intrinsic states and continuum is traced further to the regime of continuum dominance that implies the decay width collectivization and onset of super-radiance. The coexistence and interplay of internal collective motion, such as giant resonances, and decay are of particular interest. Schematic and realistic calculations illustrate changes in the strength distribution and the natural appearance of the so-called pygmy mode
Comparative analysis of collective doses received since 1976 at the Ardennes nuclear power plant
International Nuclear Information System (INIS)
Aye, Louis
1980-01-01
The analysis of the collective doses at the Centrale nucleaire des Ardennes povides valuable data about the origin of exposures in P.W.R. reactors and their evolution regarding the increase of activity of the circuits after more than 10 years of operation. The investigations led for most of the works since 1976 reveals that, in some cases, the use of sophisticated implements combined with modifications of equipments and procedures may bring appreciable savings on doses during normal operation as well as maintenance and refuelings shut-down. However, the study gives the 'reasonably achievable' limits than can be aimed in a plant on operation, the doses resulting mainly from problems that should be taken into account at design [fr
International Nuclear Information System (INIS)
Yannouleas, C.; Jang, S.
1986-01-01
The zero-temperature second RPA is generalized to finite temperatures through the use of the method of linearization of the equations of motion. After elimination of the quadruples, for low enough temperatures and within the subspace spanned by the doubles, a proper symmetrization yields an eigenvalue equation which exhibits formal properties like the simple RPA. From this second RPA eigenvalue equation, a closed formula for the spreading width of an isolated collective state is extracted. The second RPA can be recast in the form of a generalized collision term and be compared with the method of the Bethe-Salpeter equation for the two-body Green function. However, the second RPA method (and results) contrasts with the approach (and corresponding results) of the Boltzmann collision term, which is usually viewed as the appropriate agent for nuclear dissipation. (orig.)
International Nuclear Information System (INIS)
Pham Quang Minh; Tran Chi Thanh; Cao Dinh Thanh; Mai Dinh Trung; Hoang Sy Than; Nguyen Nhi Dien; Trinh Van Giap; Le Ba Thuan; Vu Tien Ha
2014-01-01
Following the Contract No.19/HD/NVCB dated July 10, 2013 signed by the President of Vietnam Atomic Energy Institute (VINATOM), an additional ministerial Project was approval by the Decision No. 526/QD-VNLNT dated July 8, 2013 by the VINATOM President in order to implement an important task for VINATOM. This project was implemented by the Institute for Nuclear Science and Technology (INST) in Hanoi as management organization and VINATOM as the owner of project results. Main objectives of this Project are to support national budget for implementing to collected the general report from previous projects which are relevant to CNEST and new research reactor, IAEA guidance documents, documents provided by ROSATOM in seminars in 2010, 2012 and 2013, report from expert visits of Ministry of Science and Technology and completed the general report about the construction project of CNEST. (author)
Modeling nuclear weak-interaction processes with relativistic energy density functionals
International Nuclear Information System (INIS)
Paar, N.; Marketin, T.; Vale, D.; Vretenar, D.
2015-01-01
Relativistic energy density functionals have become a standard framework for nuclear structure studies of ground state properties and collective excitations over the entire nuclide chart. In this paper, we review recent developments in modeling nuclear weak-interaction processes: Charge-exchange excitations and the role of isoscalar proton–neutron pairing, charged-current neutrino–nucleus reactions relevant for supernova evolution and neutrino detectors and calculation of β-decay rates for r-process nucleosynthesis. (author)
Physics with radioactive nuclear beams
International Nuclear Information System (INIS)
Boyd, R.N.; Tanihata, I.
1992-01-01
Recently developed facilities allow a wide range of new investigations of the reactions and properties of short-lived nuclei. These studies may help to solve puzzles of nuclear structure and the Big Bang. The purpose of nuclear physics is to measure properties of specific nuclides and infer from them global properties common to all nuclides. One goal, for example, is to understand nuclear sizes and matter distributions in terms of basic nuclear forces. Another is to understand the variation throughout the periodic table of the dominant quantum states, which are known as the open-quotes nuclear shell modelclose quotes states and are characterized, much as are atomic states, by a principal quantum number and by orbital and total angular momentum quantum numbers. In turn other nuclear phenomena, such as the collective excitations known as giant resonances, can be understood in terms of the shell-model configurations and basic nuclear parameters. Radioactive nuclear beam studies of reactions of short-lived nuclides have already yielded results with important ramifications in both nuclear physics and astrophysics. Nuclear physicists expect unstable nuclides to exhibit unusual structures or features that may test their understanding of known nuclear phenomena at extreme conditions, and perhaps even to reveal previously unknown nuclear phenomena, Astrophysicists, for their part, have known for several decades that processes in both Big Bang nucleosynthesis and stellar nucleosynthesis involve short-lived nuclides. Indeed, the original motivation for developing radioactive nuclear beams was astrophysical. 25 refs., 7 figs
Physics with radioactive nuclear beams
International Nuclear Information System (INIS)
Boyd, R.N.
1995-01-01
Recently developed facilities allow a wide range of new investigations of the reactions and properties of short-lived nuclei. These studies may help to solve puzzles of nuclear structure and the Big Bang. The purpose of nuclear physics is to measure properties of specific nuclides and infer from them global properties common to all nuclides, for example, is to understand nuclear sizes and matter distributions in terms of basic nuclear forces. Another is to understand the variation throughout the periodic table of the dominant quantum states, which are known as the open-quotes nuclear shell model close quotes states and are characterized, much as are atomic states, by a principal quantum number and by orbital and total angular momentum quantum numbers. In turn other nuclear phenomena, such as the collective excitations known as giant resonances, can be understood in terms of the shell-model configurations and basic nuclear parameters. Radioactive nuclear beam studies of reactions of short-lived nuclides have already yielded results with important ramifications in both nuclear physics and astrophysics. Nuclear physicists expect unstable nuclides to exhibit unusual structures or features that may test their understanding of known nuclear phenomena at extreme conditions, and perhaps even to reveal previously unknown nuclear phenomena, Astrophysicists, for their part, have known for several decades that processes in both Big Bang nucleosynthesis and stellar nucleosynthesis involve short-lived nuclides. Indeed, the original motivation for developing radioactive nuclear beams was astrophysical. (author). 25 refs., 7 figs
Gordon Conference on Nuclear Research
International Nuclear Information System (INIS)
Austin, S.M.
1983-09-01
Session topics were: quarks and nuclear physics; anomalons and anti-protons; the independent particle structure of nuclei; relativistic descriptions of nuclear structure and scattering; nuclear structure at high excitation; advances in nuclear astrophysics; properties of nuclear material; the earliest moments of the universe; and pions and spin excitations in nuclei