International Nuclear Information System (INIS)
Xu Chang; Li Baoan; Chen Liewen; Ko, Che Ming
2011-01-01
Using the Hugenholtz-Van Hove theorem, we derive general expressions for the quadratic and quartic symmetry energies in terms of the isoscalar and isovector parts of single-nucleon potentials in isospin asymmetric nuclear matter. These expressions are useful for gaining deeper insights into the microscopic origins of the uncertainties in our knowledge on nuclear symmetry energies especially at supra-saturation densities. As examples, the formalism is applied to two model single-nucleon potentials that are widely used in transport model simulations of heavy-ion reactions.
Can the nuclear symmetry potential at supra-saturation densities be negative?
International Nuclear Information System (INIS)
Yong Gaochan
2010-01-01
In the framework of an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, for the central 197 Au+ 197 Au reaction at an incident beam energy of 400 MeV/nucleon, the effect of nuclear symmetry potential at supra-saturation densities on the preequilibrium clusters emission is studied. It is found that for the positive symmetry potential at supra-saturation densities the neutron-to-proton ratio of lighter clusters with mass number A≤3[(n/p) A≤3 ] is larger than that of the heavier clusters with mass number A>3[(n/p) A>3 ], whereas for the negative symmetry potential at supra-saturation densities the (n/p) A≤3 is smaller than the (n/p) A>3 . This may be considered as a probe of the negative symmetry potential at supra-saturation densities.
Partial symmetries in nuclear spectroscopy
International Nuclear Information System (INIS)
Leviatan, A.
1996-01-01
The notions of exact, dynamical and partial symmetries are discussed in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. (Author)
Symmetries in nuclear structure
Allaart, K; Dieperink, A
1983-01-01
The 1982 summer school on nuclear physics, organized by the Nuclear Physics Division of the Netherlands' Physical Society, was the fifth in a series that started in 1963. The number of students attending has always been about one hundred, coming from about thirty countries. The theme of this year's school was symmetry in nuclear physics. This book covers the material presented by the enthusi astic speakers, who were invited to lecture on this subject. We think they have succeeded in presenting us with clear and thorough introductory talks at graduate or higher level. The time schedule of the school and the location allowed the participants to make many informal contacts during many social activities, ranging from billiards to surf board sailing. We hope and expect that the combination of a relaxed atmosphere during part of the time and hard work during most of the time, has furthered the interest in, and understanding of, nuclear physics. The organization of the summer school was made possible by substantia...
Nuclear symmetries at low isospin
International Nuclear Information System (INIS)
Juillet, Olivier
1999-01-01
With the development of radioactive beams, an area of intense research in nuclear physics concerns the structure of exotic systems with roughly equal numbers of protons and neutrons. These nuclei might in fact develop a proton-neutron superfluidity whose importance compared to pairing correlations between like nucleons is currently investigated. The work presented in this thesis suggests to look at such a competition in an algebraic framework based on a Wigner SU(4) symmetry that combines the pseudo-spin and isospin degrees of freedom. After a detailed review of group theory in quantum mechanics, the validity of the pseudo-SU(4) classification is shown via a direct analysis of realistic shell model states. Its consequences on binding energies and β decay are also studied. Moreover, a simplified boson realisation with zero orbital angular momentum is used to find some physical features of N=Z nuclei such as the condensation of α-like structures or the destruction of isoscalar superfluid correlations by the spin-orbit potential. Finally, another bosonization scheme that includes quadrupole degrees of freedom (IBM-4 model) is tested for the first time by diagonalization of a full Hamiltonian deduced from a realistic shell model interaction. The quality of the results, especially for odd-odd nuclei, allows one to consider this boson approximation as an alternative to standard fermionic approaches for the collective structure of the exotic line N∼Z=28-50. (author) [fr
Nuclear probes of fundamental symmetries
International Nuclear Information System (INIS)
Adelberger, E.G.
1983-01-01
Nuclear experiments which probe the parity (P) and time-reversal (T) symmetries and lepton-number conservation are reviewed. The P-violating NN interaction, studied in the NN system and in light nuclei, provides an unique window on ΔS=0 hadronic weak processes. Results are in accord with expectations. Sensitive searches for T-violation via detailed balance, T-odd correlations in γ and β-decay, and a possible neutron electric dipole moment (EDM) are discussed. No T-violation is observed. The EDM limit is almost good enough to eliminate one of the leading theoretical explanations for CP violation. Experimental studies of double β-decay are reviewed. Although ββ nu nu decay has been convincingly detected in geochemical experiments there is no evidence for the lepton number violating ββ decay mode
Nuclear symmetry energy: An experimental overview
Indian Academy of Sciences (India)
Abstract. The nuclear symmetry energy is a fundamental quantity important for study- ing the structure of systems as diverse as the atomic nucleus and the neutron star. Con- siderable efforts are being made to experimentally extract the symmetry energy and its dependence on nuclear density and temperature. In this article ...
Nuclear symmetry energy: An experimental overview
Indian Academy of Sciences (India)
The nuclear symmetry energy is a fundamental quantity important for studying the structure of systems as diverse as the atomic nucleus and the neutron star. Considerable efforts are being made to experimentally extract the symmetry energy and its dependence on nuclear density and temperature. In this article, the ...
Density content of nuclear symmetry energy from nuclear observables
Indian Academy of Sciences (India)
The density content of nuclear symmetry energy remains poorly constrained. Our recent results for the density content of the nuclear symmetry energy, around the saturation density, extracted using experimental data for accurately known nuclear masses, giant resonances and neutron-skin thickness in heavy nuclei are.
Chiral symmetry and nuclear matter equation of state
Indian Academy of Sciences (India)
Abstract. We investigate the effect on the nuclear matter equation of state (EOS) due to modifica- tion of meson and nucleon parameters in nuclear medium as a consequence of partial restoration of chiral symmetry. To get the EOS, we have used Brueckner–Bethe–Golstone formalism with Bonn-B potential as two-body ...
Nuclear symmetry energy: An experimental overview
Indian Academy of Sciences (India)
The nuclear matter symmetry energy, which is defined as the difference in energy per nucleon between the pure neutron matter and the symmetric nuclear matter ... Hartree–Fock (DBHF) calculations, or the phenomenological calculations such as the Skyrme Hartree–Fock (SHF) and the relativistic mean field (RMF) calcula-.
Density content of nuclear symmetry energy from nuclear observables
Indian Academy of Sciences (India)
2014-10-11
Oct 11, 2014 ... Home; Journals; Pramana – Journal of Physics; Volume 83; Issue 5 ... The nuclear symmetry energy at a given density measures the energy transferred in converting symmetric nuclear matter into the pure neutron matter. ... Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064, India ...
International Nuclear Information System (INIS)
Guo, Wenmei; Yong, Gaochan; Wang, Yongjia; Li, Qingfeng; Zhang, Hongfei; Zuo, Wei
2014-01-01
Within two different frameworks of isospin-dependent transport model, effect of nuclear symmetry energy at supradensities on the isospin-fractionation (IsoF) was investigated. With positive/negative symmetry potential at supradensities (i.e., values of symmetry energy increase/decrease with density above saturation density), for energetic nucleons, the value of neutron to proton ratio of free nucleons is larger/smaller than that of bound nucleon fragments. Compared with extensively studied quantitative observables of nuclear symmetry energy, the normal or abnormal isospin-fractionation of energetic nucleons can be a qualitative probe of nuclear symmetry energy at supradensities
Density content of nuclear symmetry energy from nuclear observables
Indian Academy of Sciences (India)
nuclear symmetry energy, around the saturation density, extracted using experimental data for accurately known nuclear masses, giant resonances and neutron-skin thickness in heavy nuclei are summarized. Keywords. ... the difference between the neutron and proton root mean square (r.m.s.) radii. The cor- relation of ...
International Nuclear Information System (INIS)
Li Baoan; Chen Liewen; Fattoyev, Farrukh J; Newton, William G; Xu Chang
2013-01-01
Significant progress has been made in recent years in constraining nuclear symmetry energy at and below the saturation density of nuclear matter using data from both terrestrial nuclear experiments and astrophysical observations. However, many interesting questions remain to be studied especially at supra-saturation densities. In this lecture note, after a brief summary of the currently available constraints on nuclear symmetry energy near the saturation density we first discuss the relationship between the symmetry energy and the isopin and momentum dependence of the single-nucleon potential in isospin-asymmetric nuclear medium. We then discuss several open issues regarding effects of the tensor force induced neutron-proton short-range correlation (SRC) on nuclear symmetry energy. Finally, as an example of the impacts of nuclear symmetry energy on properties of neutron stars and gravitational waves, we illustrate effects of the high-density symmetry energy on the tidal polarizability of neutron stars in coalescing binaries.
Probing the density content of the nuclear symmetry energy
Indian Academy of Sciences (India)
Abstract. The nature of equation of state for the neutron star matter is crucially governed by the density dependence of the nuclear symmetry energy. We attempt to probe the behaviour of the nuclear symmetry energy around the saturation density by exploiting the empirical values for volume and surface symmetry energy ...
Probing the density content of the nuclear symmetry energy
Indian Academy of Sciences (India)
2014-04-30
Apr 30, 2014 ... The nature of equation of state for the neutron star matter is crucially governed by the density dependence of the nuclear symmetry energy. We attempt to probe the behaviour of the nuclear symmetry energy around the saturation density by exploiting the empirical values for volume and surface symmetry ...
International Nuclear Information System (INIS)
Xu, Jun; Ma, Hong-Ru; Chen, Lie-Wen; Li, Bao-An
2007-01-01
Within a self-consistent thermal model using an isospin and momentum dependent interaction (MDI) constrained by the isospin diffusion data in heavy-ion collisions, we investigate the temperature dependence of the symmetry energy E sym (ρ,T) and symmetry free energy F sym (ρ,T) for hot, isospin asymmetric nuclear matter. It is shown that the symmetry energy E sym (ρ,T) generally decreases with increasing temperature while the symmetry free energy F sym (ρ,T) exhibits opposite temperature dependence. The decrement of the symmetry energy with temperature is essentially due to the decrement of the potential energy part of the symmetry energy with temperature. The difference between the symmetry energy and symmetry free energy is found to be quite small around the saturation density of nuclear matter. While at very low densities, they differ significantly from each other. In comparison with the experimental data of temperature dependent symmetry energy extracted from the isotopic scaling analysis of intermediate mass fragments (IMF's) in heavy-ion collisions, the resulting density and temperature dependent symmetry energy E sym (ρ,T) is then used to estimate the average freeze-out density of the IMF's
Nuclear symmetry energy in density dependent hadronic models
International Nuclear Information System (INIS)
Haddad, S.
2008-12-01
The density dependence of the symmetry energy and the correlation between parameters of the symmetry energy and the neutron skin thickness in the nucleus 208 Pb are investigated in relativistic Hadronic models. The dependency of the symmetry energy on density is linear around saturation density. Correlation exists between the neutron skin thickness in the nucleus 208 Pb and the value of the nuclear symmetry energy at saturation density, but not with the slope of the symmetry energy at saturation density. (author)
Relativistic nuclear physics: symmetry and the correlation depletion principle
International Nuclear Information System (INIS)
Baldin, A.M.
1996-01-01
The author's view on the role of symmetry in fundamental physics is presented. The concept of the 'symmetry of solutions' is analyzed. It is stressed that it is impossible to deduce the basic laws of relativistic nuclear physics from the QCD Lagrangians without recourse to additional hypotheses about the symmetry of solutions (Green functions). The test of these hypotheses is the major prospect of the study of hadron and nuclear collisions. Special importance is given to the Correlation Depletions Principle that makes it possible to construct mathematical models of relativistic nuclear physics, and analyze, by using simple terms, topologically complicated events of nucleus-nucleus collisions. 15 refs., 4 figs
Fluctuations and symmetry energy in nuclear fragmentation dynamics.
Colonna, M
2013-01-25
Within a dynamical description of nuclear fragmentation, based on the liquid-gas phase transition scenario, we explore the relation between neutron-proton density fluctuations and nuclear symmetry energy. We show that, along the fragmentation path, isovector fluctuations follow the evolution of the local density and approach an equilibrium value connected to the local symmetry energy. Higher-density regions are characterized by smaller average asymmetry and narrower isotopic distributions. This dynamical analysis points out that fragment final state isospin fluctuations can probe the symmetry energy of the density domains from which fragments originate.
Quark condensates in nuclear matter in the global color symmetry model of QCD
International Nuclear Information System (INIS)
Liu Yuxin; Gao Dongfeng; Guo Hua
2003-01-01
With the global color symmetry model being extended to finite chemical potential, we study the density dependence of the local and nonlocal scalar quark condensates in nuclear matter. The calculated results indicate that the quark condensates increase smoothly with the increasing of nuclear matter density before the critical value (about 12ρ 0 ) is reached. It also manifests that the chiral symmetry is restored suddenly as the density of nuclear matter reaches its critical value. Meanwhile, the nonlocal quark condensate in nuclear matter changes nonmonotonously against the space-time distance among the quarks
Symplectic symmetry in the nuclear shell model
French, J.B.
The nature of the general two-particle interaction which is compatible with symplectic symmetry in the jj coupling shell model is investigated. The essential result is that, to within an additive constant and an additive multiple of T2, the interaction should have the form of a sum of scalar
Clustering and Symmetry Energy in a Low Density Nuclear Gas
International Nuclear Information System (INIS)
Kowalski, S.; Natowitz, J.B.; Shlomo, S.; Wada, R.; Hagel, K.; Wang, J.; Materna, T.; Chen, Z.; Ma, Y.G.; Qin, L.; Botvina, A.S.; Fabris, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pesente, S.; Rizzi, V.; Viesti, G.; Cinausero, M.; Prete, G.; Keutgen, T.; El Masri, Y.; Majka, Z.; Ono, A.
2007-01-01
Temperature and density dependent symmetry energy coefficients have been derived from isoscaling analyses of the yields of nuclei with A= 64 Zn projectiles with 92 Mo and 197 Au target nuclei. The symmetry energies at low density are larger than those obtained in mean field calculations, reflecting the clustering of low density nuclear matter. They are in quite good agreement with results of a recently proposed Virial Equation of State calculation
Flavor symmetry and topology change in nuclear symmetry energy for compact stars
International Nuclear Information System (INIS)
Lee, Hyun Kyu; Rho, Mannque
2013-01-01
The nuclear symmetry energy figures crucially in the structure of asymmetric nuclei and, more importantly, in the equation of state (EoS) of compact stars. At present it is almost totally unknown, both experimentally and theoretically, in the density regime appropriate for the interior of neutron stars. Basing on a strong-coupled structure of dense baryonic matter encoded in the skyrmion crystal approach with a topology change and resorting to the notion of generalized hidden local symmetry in hadronic interactions, we address a variety of hitherto unexplored issues of nuclear interactions associated with the symmetry energy, i.e., kaon condensation and hyperons, possible topology change in dense matter, nuclear tensor forces, conformal symmetry, chiral symmetry, etc., in the EoS of dense compact-star matter. One of the surprising results coming from HLS structure that is distinct from what is given by standard phenomenological approaches is that at high density, baryonic matter is driven by renormalization group flow to the 'dilaton-limit fixed point' constrained by 'mended symmetries'. We further propose how to formulate kaon condensation and hyperons in compact-star matter in a framework anchored on a single effective Lagrangian by treating hyperons as the Callan–Klebanov kaon-skyrmion bound states simulated on crystal lattice. This formulation suggests that hyperons can figure in the stellar matter — if at all — when or after kaons condense, in contrast to the standard phenomenological approaches where the hyperons appear as the first strangeness degree of freedom in matter, thereby suppressing or delaying kaon condensation. In our simplified description of the stellar structure in terms of symmetry energies, which is compatible with that of the 1.97 solar mass star, kaon condensation plays a role of 'doorway state' to strange quark matter. (author)
Symmetries in molecular and nuclear physics
International Nuclear Information System (INIS)
Iachello, F.
1987-01-01
Algebric techniques (interacting boson and boson-fermion models) used in the study of nuclear structures, and are able to predict properties of complex nuclei with high accuracy described. (M.C.K.) [pt
The symmetry energy in nuclei and in nuclear matter
Dieperink, A. E. L.; Van Isacker, P.
We discuss to what extent information on ground-state properties of finite nuclei ( energies and radii) can be used to obtain constraints on the symmetry energy in nuclear matter and its dependence on the density. The starting point is a generalized Weizsacker formula for ground-state energies. In
The symmetry energy in nuclei and in nuclear matter
Van Isacker, P.; Dieperink, A. E. L.
2006-01-01
We discuss to what extent information on ground-state properties of finite nuclei (energies and radii) can be used to obtain constraints on the symmetry energy in nuclear matter and its dependence on the density. The starting point is a generalized Weizsacker formula for ground-state energies. In
Non-geometric fluxes and mixed-symmetry potentials
Bergshoeff, E.A.; Penas, V.A.; Riccioni, F.; Risoli, S.
2015-01-01
We discuss the relation between generalised fluxes and mixed-symmetry potentials. We refer to the fluxes that cannot be described even locally in the framework of supergravity as ‘non-geometric’. We first consider the NS fluxes, and point out that the non-geometric R flux is dual to a mixed-symmetry
Chemical potential and reaction electronic flux in symmetry controlled reactions.
Vogt-Geisse, Stefan; Toro-Labbé, Alejandro
2016-07-15
In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
Pure Neutron Matter Constraints and Nuclear Symmetry Energy
International Nuclear Information System (INIS)
Fattoyev, F J; Newton, W G; Xu, Jun; Li, Bao-An
2013-01-01
In this review, we will discuss the results of our recent work [1] to study the general optimization of the pure isovector parameters of the popular relativistic mean-field (RMF) and Skyrme-Hartree-Fock (SHF) nuclear energy-density functionals (EDFs), using constraints on the pure neutron matter (PNM) equation of state (EoS) from recent ab initio calculations. By using RMF and SHF parameterizations that give equivalent predictions for ground-state properties of doubly magic nuclei and properties of symmetric nuclear matter (SNM) and PNM, we found that such optimization leads to broadly consistent symmetry energy J and its slope parameter L at saturation density within a tight range of α(J) sym , (b) the symmetry energy at supra-saturation densities, and (c) the radius of neutron stars.
Time reversal symmetry breaking effects in resonant nuclear reactions
International Nuclear Information System (INIS)
Feshbach, H.; Hussein, M.S.; Kerman, A.K.
1995-01-01
We incorporate time reversal symmetry breaking (TRSB) effects into the theory of compound nuclear reactions. We show that the only meaningful test of TRSB in the overlapping resonances regime is through the study of cross-section correlations. The effect is channel-dependent. In the isolated resonance regime, we employ K-matrix theory to show the impact of TRSB using the fact that when only one eigen-channel participates in populating and depopulating the compound resonance. (orig.)
Nuclear Symmetry Energy Probed by Neutron Skin Thickness of Nuclei
International Nuclear Information System (INIS)
Centelles, M.; Roca-Maza, X.; Vinas, X.; Warda, M.
2009-01-01
We describe a relation between the symmetry energy coefficients c sym (ρ) of nuclear matter and a sym (A) of finite nuclei that accommodates other correlations of nuclear properties with the low-density behavior of c sym (ρ). Here, we take advantage of this relation to explore the prospects for constraining c sym (ρ) of systematic measurements of neutron skin sizes across the mass table, using as example present data from antiprotonic atoms. The found constraints from neutron skins are in harmony with the recent determinations from reactions and giant resonances
Potential for nuclear terrorism
International Nuclear Information System (INIS)
Jenkins, B.M.
1977-05-01
The question of whether or not terrorists will ''go nuclear'' is discussed. It is possible, although there is no historical evidence that any criminal or terrorist group ever made any attempt to acquire nuclear material for use in an explosive or dispersal device. In terms of intentions, psychotics are potential nuclear terrorists, but in terms of capabilities, they are the farthest away from being able to acquire a nuclear weapon. The history of nuclear incidents in the U.S. and abroad is reviewed. As the nuclear industry expands, the number of low-level incidents (bomb threats, pilferage, etc.) will increase also, but not necessarily escalate to more serious incidents. Terrorists may ''go nuclear'' solely for the publicity value; nuclear hoaxes may be attenpted. Nuclear terrorism seems more attractive as a threat than as an action. But the nature of the threat may change in the future, and the danger of imitation of a successful nuclear terrorist act is pointed out
The spin symmetry for deformed generalized Poeschl-Teller potential
International Nuclear Information System (INIS)
Wei Gaofeng; Dong Shihai
2009-01-01
In the case of spin symmetry we solve the Dirac equation with scalar and vector deformed generalized Poeschl-Teller (DGPT) potential and obtain exact energy equation and spinor wave functions for s-wave bound states. We find that there are only positive energy states for bound states in the case of spin symmetry based on the strong regularity restriction condition λ<-η for the wave functions. The energy eigenvalue approaches a constant when the potential parameter α goes to zero. Two special cases such as generalized PT potential and standard PT potential are also briefly discussed.
Model dependence in the density content of nuclear symmetry energy
International Nuclear Information System (INIS)
Mondal, C.; Agrawal, B.K.; Singh, S.K.; Patra, S.K.; Centelles, M.; Viñas, X.; Colò, G.; Roca-Maza, X.; Paar, N.
2014-01-01
Apart from very few light nuclei, all nuclear systems in nature, starting from tiny finite nuclei to huge astrophysical objects like neutron stars, are asymmetric. Densities of these systems vary over a wide range. So, accurate knowledge of symmetry energy over a wide range of density is very essential to understand several phenomena in finite nuclei as well as in neutron stars. We have shown using a representative set of systematically varied mean models that the correlation of symmetry energy slope parameter with the neutron skin thickness in 208 Pb nucleus has a noticeable amount of model dependence. The investigations in order to unveil the source of the model dependence in such correlations are underway
Static potentials from an extended gauge symmetry
International Nuclear Information System (INIS)
Doria, R.M.; Helayel Neto, J.A.
1985-01-01
Static potentials derived from the inclusion of more than one vector field in a single simple group are calculated. A confinement mechanism including colourful unphysical particle is discussed. (Author) [pt
Directory of Open Access Journals (Sweden)
Rui Wang
2017-10-01
Full Text Available We establish a relation between the equation of state of nuclear matter and the fourth-order symmetry energy asym,4(A of finite nuclei in a semi-empirical nuclear mass formula by self-consistently considering the bulk, surface and Coulomb contributions to the nuclear mass. Such a relation allows us to extract information on nuclear matter fourth-order symmetry energy Esym,4(ρ0 at normal nuclear density ρ0 from analyzing nuclear mass data. Based on the recent precise extraction of asym,4(A via the double difference of the “experimental” symmetry energy extracted from nuclear masses, for the first time, we estimate a value of Esym,4(ρ0=20.0±4.6 MeV. Such a value of Esym,4(ρ0 is significantly larger than the predictions from mean-field models and thus suggests the importance of considering the effects of beyond the mean-field approximation in nuclear matter calculations.
Probing the nuclear symmetry energy at high densities with nuclear reactions
Leifels, Y.
2017-11-01
The nuclear equation of state is a topic of highest current interest in nuclear structure and reactions as well as in astrophysics. The symmetry energy is the part of the equation of state which is connected to the asymmetry in the neutron/proton content. During recent years a multitude of experimental and theoretical efforts on different fields have been undertaken to constraint its density dependence at low densities but also above saturation density (ρ_0=0.16 fm ^{-3} . Conventionally the symmetry energy is described by its magnitude S_v and the slope parameter L , both at saturation density. Values of L = 44 -66MeV and S_v=31 -33MeV have been deduced in recent compilations of nuclear structure, heavy-ion reaction and astrophysics data. Apart from astrophysical data on mass and radii of neutron stars, heavy-ion reactions at incident energies of several 100MeV are the only means do access the high density behaviour of the symmetry energy. In particular, meson production and collective flows upto about 1 AGeV are predicted to be sensitive to the slope of the symmetry energy as a function of density. From the measurement of elliptic flow of neutrons with respect to charged particles at GSI, a more stringent constraint for the slope of the symmetry energy at supra-saturation densities has been deduced. Future options to reach even higher densities will be discussed.
Chubb, Scott
2007-03-01
Only recently (talk by P.A. Mosier-Boss et al, in this session) has it become possible to trigger high energy particle emission and Excess Heat, on demand, in LENR involving PdD. Also, most nuclear physicists are bothered by the fact that the dominant reaction appears to be related to the least common deuteron(d) fusion reaction,d+d ->α+γ. A clear consensus about the underlying effect has also been illusive. One reason for this involves confusion about the approximate (SU2) symmetry: The fact that all d-d fusion reactions conserve isospin has been widely assumed to mean the dynamics is driven by the strong force interaction (SFI), NOT EMI. Thus, most nuclear physicists assume: 1. EMI is static; 2. Dominant reactions have smallest changes in incident kinetic energy (T); and (because of 2), d+d ->α+γ is suppressed. But this assumes a stronger form of SU2 symmetry than is present; d+d ->α+γ reactions are suppressed not because of large changes in T but because the interaction potential involves EMI, is dynamic (not static), the SFI is static, and because the two incident deuterons must have approximate Bose Exchange symmetry and vanishing spin. A generalization of this idea involves a resonant form of reaction, similar to the de-excitation of an atom. These and related (broken gauge) symmetry EMI effects on LENR are discussed.
Dynamic Isovector Reorientation of Deuteron as a Probe to Nuclear Symmetry Energy.
Ou, Li; Xiao, Zhigang; Yi, Han; Wang, Ning; Liu, Min; Tian, Junlong
2015-11-20
We present the calculations on a novel reorientation effect of deuteron attributed to isovector interaction in the nuclear field of heavy target nuclei. The correlation angle determined by the relative momentum vector of the proton and the neutron originating from the breakup deuteron, which is experimentally detectable, exhibits significant dependence on the isovector nuclear potential but is robust against the variation of the isoscaler sector. In terms of sensitivity and cleanness, the breakup reactions induced by the polarized deuteron beam at about 100 MeV/u provide a more stringent constraint to the symmetry energy at subsaturation densities.
Probing the nuclear symmetry energy with heavy ion collisions
Coupland, Daniel David Schechtman
There are two distinct components involved in using heavy ion collisions to constrain the density dependence of the symmetry energy. On one hand, observables sensitive to the symmetry energy must be identified and measured with enough precision to provide meaningful constraints. On the other hand, nuclear reaction simulations are used to predict those observables for different possible forms of the symmetry energy. Examination of both components and the interface between them is important to improve the constraints. This thesis contributes to both the experimental and theoretical parts of this endeavor. First, we examine the uncertainties in the simulation of the isospin diffusion observable by varying the input physics within the pBUU transport code. In addition to the symmetry energy, several other uncertain parts of the calculation affect isospin diffusion, most notably the in-medium nucleon-nucleon cross sections and light cluster production. There is also a difference in the calculated isospin transport ratios depending on whether they are computed using the isospin asymmetry of the heavy residue or of all forward-moving fragments. We suggest that measurements comparing these two quantities would help place constraints on the input physics, including the density dependence of the symmetry energy. Second, we present a measurement of the neutron and proton kinetic energy spectra emitted from central collisions of 124Sn + 124Sn and 112Sn + 112Sn at beam energies of 50 MeV per nucleon and 120 MeV per nucleon. Previous transport simulations indicate that ratios of these spectra are sensitive to the density dependence of the symmetry energy and to the isovector momentum dependence of the mean field. Protons were detected in the Large Area Silicon Strip Array (LASSA) and neutrons were detected in the MSU Neutron Walls. The multiplicity of charged particles detected in the MSU Miniball was used to determine the impact parameter of the collisions. Several thin
Imprints of the nuclear symmetry energy on gravitational waves from deformed pulsars
International Nuclear Information System (INIS)
Li, Baoan; Krastev, P.G.
2010-01-01
The density dependence of nuclear symmetry energy is a critical input for understanding many interesting phenomena in astrophysics and cosmology. We report here effects of the nuclear symmetry energy partially constrained by terrestrial laboratory experiments on the strength of gravitational waves (GWs) from deformed pulsars at both low and high rotational frequencies. (author)
International Nuclear Information System (INIS)
Xu Chang; Li Baoan
2010-01-01
Taking into account more accurately the isospin dependence of nucleon-nucleon interactions in the in-medium many-body force term of the Gogny effective interaction, new expressions for the single-nucleon potential and the symmetry energy are derived. Effects of both the spin (isospin) and the density dependence of nuclear effective interactions on the symmetry potential and the symmetry energy are examined. It is shown that they both play a crucial role in determining the symmetry potential and the symmetry energy at suprasaturation densities. The improved single-nucleon potential will be useful for more accurate simulation of nuclear reactions induced by rare-isotope beams within transport models.
PT-symmetry and Non-Central Potentials
Directory of Open Access Journals (Sweden)
G. Lévai
2007-01-01
Full Text Available We present a general procedure by which solvable non-central potentials can be obtained in 2 and 3 dimensions by the separation of the angular and radial variables. The method is applied to generate solvable non-central PT-symmetric potentials in polar coordinates. General considerations are presented concerning the PT transformation properties of the eigenfunctions, their pseudo-norm and the nature of the energy eigenvalues. It is shown that within the present framework the spontaneous breakdown of PT symmetry can be implemented only in two dimensions.
International Nuclear Information System (INIS)
Wehrhahn, R.F.; Cooper, I.L.
1992-05-01
Analysis of the dynamical symmetry of a system is used to predict properties arising from its supersymmetric quantum mechanical treatment. Two applications of the so(2,1) algebra, the Coulomb potential and Morse oscillator potential which display different structure with respect to the dynamical symmetry, are studied. This difference is shown to be responsible for the behaviour of the respective supersymmetric partner potentials. (orig.)
PT symmetry breaking in non-central potentials
International Nuclear Information System (INIS)
Levai, G.
2007-01-01
Complete text of publication follows. PT-symmetric systems represent a special example for non-hermitian problems in quantum mechanics. The Hamiltonian of these systems is invariant under the simultaneous action of the P space and T time inversion operations. They resemble hermitian problems in that they typically possess real energy spectrum. However, increasing non-hermiticity, e.g. the imaginary potential component the real energy eigenvalues merge pairwise and turn into complex conjugate pairs and at the same time, the energy eigenstates cease to be eigenstates of the PT operator. The mechanism of this spontaneous breakdown of PT symmetry has been investigated in one spatial dimension, and our aim was to extend these studies to higher dimensions. Assuming that the solutions of the Schroedinger equation -Δψ(r) + V (r)ψ(r) = Eψ(r) can be obtained by the separation of the radial and angular variables, we substitute ψ(r,θ,φ) = r -1 φ(r) sin -1/2 ω(θ)τ(ψ) in (4), where r [0,∞), θ [0,π] and ψ [0,2π]. Further, we assume that the angular components of the wave function satisfy ω' = (P(θ) - p)ω, τ' = (K(ψ) - k)τ, where τ(ψ) has to be defined with periodic boundary conditions. Then the complete three-dimensional problem becomes solvable if the non-central potential takes the form V(r,θ,ψ) = V 0 (r)+ K(ψ)/r 2 sin 2 θ + P(θ)/r 2 - k-1/4/r 2 sin 2 θ. Here V 0 (r) is a central potential appearing in -φ'+[V 0 (r) + 1/r 2 (p - 1/4] φ - Eφ = 0. Note that is formally identical with a conventional radial Schroedinger equation complete with a centrifugal term. In order to solve properly, the state dependence of has to be eliminated, i.e. its dependence on k has to be cancelled by combining the last two terms. This effectively means that has to be solved with a potential P(θ) that contains a sin -2 θ type term. Next we investigate under which conditions the non-central potential exhibits PT symmetry. It is seen that space reflection P : r → -r
Interaction potentials and their effect on crystal nucleation and symmetry
International Nuclear Information System (INIS)
Hsu, C.S.; Rahman, A.
1979-01-01
Molecular dynamics technique has been used to study the effect of the interaction potential on crystal nucleation and the symmetry of the nucleated phase. Four systems, namely rubidium, Lennard-Jones, rubidium-truncated, and Lennard-Jones-truncated, have been studied each at reduced density 0.95. Two types of calculations were performed. Firstly, starting from a liquid state, each system was quenched rapidly to a reduced temperature of approx.0.1. The nucleation process for these systems was monitored by studying the time dependence of temperature and the pair correlation function, and the resulting crystalline structure analyzed using among other properties the Voronoi polyhedra. Only in the case of rubidium was a b.c.c. structure nucleated. In the other three cases we obtained a f.c.c. ordering. Secondly, we have studied the effect of changing the interaction potential in a system which has already achieved an ordered state under the action of some other potential. After establishing a b.c.c. structure in a rubidium system, the change in the symmetry of the system was studied when the pair potential was modified to one of the other three forms. The results from both types of calculations are consistent: the rubidium potential leads to a b.c.c. structure while the other three potentials give an f.c.c. structure. Metastable disordered structures were not obtained in any of the calculations. However, the time elapse between the moment when the system is quick-quenched and the moment when nucleation occurs appears to depend upon the potential of interaction
Global symmetries and flat potentials in the compactified superstring
International Nuclear Information System (INIS)
Li, S.P.; Peschanski, R.; Savoy, C.A.
1986-01-01
Global symmetries of the D=4 supergravity effective theory consistent with the compactification of the superstring are shown to form an SU(1.1) x U(1) group of transformations acting on the dilaton, axion and matter fields. These are exact invariances of the Kaehler potential if they are preserved by integration over Kaluza-Klein massive states. A key role is played by the cubic superpotential which is also essential in implementing flatness of the scalar potential, a vanishing cosmological constant and thus effective global supersymmetry in the matter sector, at the classical level. This is shown by an explicit computation of the scalar potential. If only an axion-like non-compact subgroup is left unbroken by the superpotential, the cosmological constant turns out to be negative in some cases
Leviatan, A
2009-07-24
We consider several classes of symmetries of the Dirac Hamiltonian in 3 + 1 dimensions, with axially deformed scalar and vector potentials. The symmetries include the known pseudospin and spin limits and additional symmetries which occur when the potentials depend on different variables. Supersymmetries are observed within each class and the corresponding charges are identified.
International Nuclear Information System (INIS)
Leviatan, A.
2009-01-01
We consider several classes of symmetries of the Dirac Hamiltonian in 3+1 dimensions, with axially deformed scalar and vector potentials. The symmetries include the known pseudospin and spin limits and additional symmetries which occur when the potentials depend on different variables. Supersymmetries are observed within each class and the corresponding charges are identified.
Probing the density content of the nuclear symmetry energy
Indian Academy of Sciences (India)
0.022 fm. In the following sections, we present some of our recent results [12,13] for the values of. L(ρ0) and rskin of 208Pb extracted using empirical values of the volume symmetry energy and surface symmetry energy coefficients [14] estimated ...
Nuclear symmetry energy and the neutron skin in neutron-rich nuclei
Dieperink, AEL; Dewulf, Y; Van Neck, D; Waroquier, M; Rodin, [No Value
2003-01-01
The symmetry energy for nuclear matter and its relation to the neutron. skin in finite nuclei is discussed. The symmetry energy as a function of density obtained in a self-consistent Green function approach is presented and compared to the results of other recent theoretical approaches. A partial
Liu, Zhi Wei; Qian, Zhuang; Xing, Ruo Yu; Niu, Jia Rui; Sun, Bao Yuan
2018-02-01
Adopting the density dependent relativistic mean-field (RMF) and relativistic Hartree-Fock (RHF) approaches, the properties of the nuclear fourth-order symmetry energy S4 are studied within the covariant density functional (CDF) theory. It is found that the fourth-order symmetry energies are suppressed in RHF at both saturation and supranuclear densities, where the extra contribution from the Fock terms is demonstrated, specifically via the isoscalar meson-nucleon coupling channels. The reservation of S4 and higher-order symmetry energies in the nuclear equation of state then affects essentially the prediction of neutron star properties, which is illustrated in quantities such as the proton fraction, the core-crust transition density, as well as the fraction of crustal moment of inertia. Since the Fock terms enhance the density dependence of the thermodynamical potential, the RHF calculations predict systematically smaller values of density, proton fraction, and pressure at the core-crust transition boundary of neutron stars than density dependent RMF ones. In addition, a linear anticorrelation between the core-crust transition density ρt and the density slope of symmetry energy L is found which is then utilized to constrain the core-crust transition density as ρt˜[0.069 ,0.098 ] fm-3 with the recent empirical information on L . The study clarifies the important role of the fourth-order symmetry energy in determining the properties of nuclear matter at extreme isospin or density conditions.
Symmetry rules for the indirect nuclear spin-spin coupling tensor revisited
Buckingham, A. D.; Pyykkö, P.; Robert, J. B.; Wiesenfeld, L.
The symmetry rules of Buckingham and Love (1970), relating the number of independent components of the indirect spin-spin coupling tensor J to the symmetry of the nuclear sites, are shown to require modification if the two nuclei are exchanged by a symmetry operation. In that case, the anti-symmetric part of J does not transform as a second-rank polar tensor under symmetry operations that interchange the coupled nuclei and may be called an anti-tensor. New rules are derived and illustrated by simple molecular models.
Exact RG invariance and symmetry improved 2PI effective potential
Directory of Open Access Journals (Sweden)
Apostolos Pilaftsis
2017-07-01
Full Text Available The Symmetry Improved Two-Particle-Irreducible (SI2PI formalism is a powerful tool to calculate the effective potential beyond perturbation theory, whereby infinite sets of selective loop-graph topologies can be resummed in a systematic and consistent manner. In this paper we study the Renormalization-Group (RG properties of this formalism, by proving for the first time a number of new field-theoretic results. First, the RG runnings of all proper 2PI couplings are found to be UV finite, in the Hartree–Fock and sunset approximations of the 2PI effective action. Second, the SI2PI effective potential is exactly RG invariant, in contrast to what happens in the ordinary One-Particle-Irreducible (1PI perturbation theory, where the effective potential is RG invariant only up to higher orders. Finally, we show how the effective potential of an O(2 theory evaluated in the SI2PI framework, appropriately RG improved, can reach a higher level of accuracy, even up to one order of magnitude, with respect to the corresponding one obtained in the 1PI formalism.
Chiral symmetry and nuclear matter equation of state
Indian Academy of Sciences (India)
to play a lesser role. The spontaneous breaking of the chiral symmetry is signaled by the non-vanishing values in physical vacuum of the quark and gluon condensates [4–6]. Cal- culations based on chiral perturbation theory and QCD sum rule (QSR) indicate that values of these condensates are reduced when the hadrons ...
Test of nuclear wave functions for pseudospin symmetry.
Ginocchio, J N; Leviatan, A
2001-08-13
Using the fact that pseudospin is an approximate symmetry of the Dirac Hamiltonian with realistic scalar and vector mean fields, we derive the wave functions of the pseudospin partners of eigenstates of a realistic Dirac Hamiltonian and compare these wave functions with the wave functions of the Dirac eigenstates.
Test of Nuclear Wave Functions for Pseudospin Symmetry
Energy Technology Data Exchange (ETDEWEB)
Ginocchio, J. N.; Leviatan, A.
2001-08-13
Using the fact that pseudospin is an approximate symmetry of the Dirac Hamiltonian with realistic scalar and vector mean fields, we derive the wave functions of the pseudospin partners of eigenstates of a realistic Dirac Hamiltonian and compare these wave functions with the wave functions of the Dirac eigenstates.
Test of Nuclear Wave Functions for Pseudospin Symmetry
International Nuclear Information System (INIS)
Ginocchio, J. N.; Leviatan, A.
2001-01-01
Using the fact that pseudospin is an approximate symmetry of the Dirac Hamiltonian with realistic scalar and vector mean fields, we derive the wave functions of the pseudospin partners of eigenstates of a realistic Dirac Hamiltonian and compare these wave functions with the wave functions of the Dirac eigenstates
Accessing the nuclear symmetry energy in Ca+Ca collisions
Directory of Open Access Journals (Sweden)
Chbihi A.
2012-07-01
Full Text Available The status of the analysis of the INDRA-VAMOS experiement performed at GANIL, using the reactions 40,48Ca+40,48Ca reactions at 35AMeV, are presented. Isotopic distributions of fragments produced in multifragmentation events provide information on the importance of the surface term contribution in the symmetry energy by comparison to AMD predictions.
Charge symmetry of the nuclear force as off-shell constraint
International Nuclear Information System (INIS)
Sauer, P.U.
1975-01-01
Off-shell changes are generated in the 1 S 0 nucleon-nucleon interaction using the Reid soft-core potential and unitary transformations of short range. Charge symmetry is assumed for the nuclear force. The same off-shell variations of the Reid potential are employed as the hadronic part of the proton-proton interaction and as neutron-neutron interaction. The Reid potential fits the experimental proton-proton data. It also accounts for the neutron-neutron scattering length with satisfying accuracy. The off-shell behavior of the Reid potential is varied in two different ways. First, off-shell changes consistent with the experimental proton-proton data can be selected. (auth) are performed which preserve the fit to the proton-proton data. Most transformed potentials of the type attempted here are unable to yield the correct experimental value of the neutron-neutron scattering length and have to be rejected. A simple practical rule is given according to which the off-shell changes consistent with the neutron-neutron scattering length can be selected. Second, off-shell changes are performed which leave the neutron-neutron scattering length unaltered. Transformed potentials of this type have usually been employed in nuclear-structure calculations. The potentials which exhibit large off-shell effects in nuclear structure are unable to account for the experimental proton-proton data. Their off-shell effects are therefore of no physical significance, and the potentials have to be rejected. A simple practical rule is given according to which the off-shell changes consistent with the experimental proton-proton data can be selected. (U.S.)
Alam, N.; Pais, H.; Providência, C.; Agrawal, B. K.
2017-05-01
The spinodal instabilities in hot asymmetric nuclear matter and some important critical parameters derived thereof are studied by using six different families of relativistic mean-field models. The slopes of the symmetry energy coefficient vary over a wide range within each family. The critical densities and proton fractions are more sensitive to the symmetry energy slope parameter at temperatures much below its critical value (Tc˜14 -16 MeV ). The spread in the critical proton fraction at a given symmetry energy slope parameter is noticeably larger near Tc, indicating that the equation of state of warm asymmetric nuclear matter at subsaturation densities is not sufficiently constrained. The distillation effects are sensitive to the density dependence of the symmetry energy at low temperatures which tend to wash out with increasing temperature.
Chiral symmetry and nuclear matter equation of state
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 57; Issue 2-3 ... We investigate the effect on the nuclear matter equation of state (EOS) due to modiﬁcation of meson and nucleon parameters in nuclear medium as a consequence ... Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India ...
Nuclear tetrahedral symmetry: possibly present throughout the periodic table.
Dudek, J; Goźdź, A; Schunck, N; Miśkiewicz, M
2002-06-24
More than half a century after the fundamental, spherical shell structure in nuclei had been established, theoretical predictions indicated that the shell gaps comparable or even stronger than those at spherical shapes may exist. Group-theoretical analysis supported by realistic mean-field calculations indicate that the corresponding nuclei are characterized by the TD(d) ("double-tetrahedral") symmetry group. Strong shell-gap structure is enhanced by the existence of the four-dimensional irreducible representations of TD(d); it can be seen as a geometrical effect that does not depend on a particular realization of the mean field. Possibilities of discovering the TD(d) symmetry in experiment are discussed.
Kazakhstan without nuclear potential
International Nuclear Information System (INIS)
Abishev, M.A.; Iskakova, G.A.
2000-01-01
Kazakhstan have great heritage of the USSR military industry in form of test sites and scientific and technological complexes of different kind of weapons developments. The Republic of Kazakstan possesses of most large number of nuclear sites per head of the population. Developed industry of mining, processing of uranium ores demands solution of radioactive wastes handling problems. Therefore regime of non-proliferation and defense conversion are strategic priorities of state policy. For Kazakhstan ideals of non-proliferation of mass destruction weapon have particular meaning. Consequences of nuclear weapon tests of territory of Kazakhstan reflected on population health and on ecological balance of the region. Wide public support helps forms policy in sphere of non-proliferation of nuclear weapon. Kazakhstan executes obligations of Lisbon Protocol and consolidates the frameworks of strategic security
Triton-3He relative and differential flows and the high density behavior of nuclear symmetry
International Nuclear Information System (INIS)
Yong, Gaochan; Li, Baoan; Chen, Liewen
2010-01-01
Using a transport model coupled with a phase-space coalescence after-burner we study the triton- 3 He relative and differential transverse flows in semi-central 132 Sn + 124 Sn reactions at a beam energy of 400 MeV/nucleon. We find that the triton- 3 He pairs carry interesting information about the density dependence of the nuclear symmetry energy. The t- 3 He relative flow can be used as a particularly powerful probe of the high-density behavior of the nuclear symmetry energy. (author)
Chirally motivated K- nuclear potentials
International Nuclear Information System (INIS)
Cieply, A.; Friedman, E.; Gal, A.; Gazda, D.; Mares, J.
2011-01-01
In-medium subthreshold K-bar N scattering amplitudes calculated within a chirally motivated meson-baryon coupled-channel model are used self consistently to confront K - atom data across the periodic table. Substantially deeper K - nuclear potentials are obtained compared to the shallow potentials derived in some approaches from threshold K-bar N amplitudes, with ReV K chiral =-(85±5) MeV at nuclear matter density. When K-bar NN contributions are incorporated phenomenologically, a very deep K - nuclear potential results, ReV K c hiral+phen. =-(180±5) MeV, in agreement with density dependent potentials obtained in purely phenomenological fits to the data. Self consistent dynamical calculations of K - -nuclear quasibound states generated by V K chiral are reported and discussed.
International Nuclear Information System (INIS)
Yong, G.-C.; Li Baoan; Chen Liewen
2008-01-01
Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process pn→pnγ. Very interestingly, nevertheless, the ratio of hard photon spectra R 1/2 (γ) from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of 132 Sn + 124 Sn and 112 Sn + 112 Sn at E beam /A=50 MeV, for example, the R 1/2 (γ) displays a rise up to 15% when the symmetry energy is reduced by about 20% at ρ=1.3ρ 0 which is the maximum density reached in these reactions
Finite-temperature effective potential of a system with spontaneously broken symmetry
Energy Technology Data Exchange (ETDEWEB)
Zemskov, E.P. [Yaroslavl State Technical Univ. (Russian Federation)
1995-12-01
A quantum-mechanical system with spontaneously broken symmetry is considered the effective potential is determined, and it is shown that with reduction of temperature the system undergoes a phase transition of the first kind.
The effective nuclear potential
International Nuclear Information System (INIS)
Skyrme, T.H.R.
1994-01-01
An empirical analyses is made of the mean effective internucleon potential required in the shell-model description of nuclei, allowing for the presence of many-body effects as suggested by current theory. A consistent description is found in which the effective two-body interaction acts almost entirely in even states, and the many-body effects are simulated by a repulsive three-body contact interaction. The strength of the two-body interaction is consistent with that expressed by the free scattering matrix of the two-nucleon system, and that of the three-body interaction with the 'rearrangement energy' calculated in the many-body theory. (author). 21 refs, 2 figs, 7 tabs
Nuclear energy: potentiality and implications
International Nuclear Information System (INIS)
Bahgat, Gawdat
2008-01-01
After a discussion about a broad definition of energy security and about the main challenges facing a potential nuclear renaissance, the article analyses how the European Union and the United States have addressed these challenges. There is no doubt that nuclear power will remain an important component of global energy mix, but it should not be seen as a panacea to the flows in the global energy markets [it
Amandeep, K.; Suneel, K.
2017-09-01
The present theoretical calculations have been performed within the framework of IQMD model to study a particular set of mass symmetric and asymmetric reactions (keeping total mass fixed) over a wide range of incident energies and colliding geometries. It has been observed that global as well as local nuclear stopping is influenced by the mass asymmetry of the reaction strongly. Influence of density-dependent symmetry energy has been observed in local nuclear stopping. Global stopping decreases with the increase in colliding geometry. Effect of colliding geometry on nuclear stopping is more at higher energies.
Dudek, J.; Curien, D.; Dedes, I.; Mazurek, K.; Tagami, S.; Shimizu, Y. R.; Bhattacharjee, T.
2018-02-01
We formulate criteria for identification of the nuclear tetrahedral and octahedral symmetries and illustrate for the first time their possible realization in a rare earth nucleus 152Sm. We use realistic nuclear mean-field theory calculations with the phenomenological macroscopic-microscopic method, the Gogny-Hartree-Fock-Bogoliubov approach, and general point-group theory considerations to guide the experimental identification method as illustrated on published experimental data. Following group theory the examined symmetries imply the existence of exotic rotational bands on whose properties the spectroscopic identification criteria are based. These bands may contain simultaneously states of even and odd spins, of both parities and parity doublets at well-defined spins. In the exact-symmetry limit those bands involve no E 2 transitions. We show that coexistence of tetrahedral and octahedral deformations is essential when calculating the corresponding energy minima and surrounding barriers, and that it has a characteristic impact on the rotational bands. The symmetries in question imply the existence of long-lived shape isomers and, possibly, new waiting point nuclei—impacting the nucleosynthesis processes in astrophysics—and an existence of 16-fold degenerate particle-hole excitations. Specifically designed experiments which aim at strengthening the identification arguments are briefly discussed.
Potential risks of nuclear ships
International Nuclear Information System (INIS)
Oelgaard, P.L.
1994-07-01
This report represents an attempt to evaluate the potential risks of nuclear ships. Firstly reasons are given why nuclear ship accidents will not lead to accidents of the magnitude of the Chernobyl accident. This is due to much lower content of radioactive material and to different reactor designs. Next a review is given of the types of accidents which have actually occurred. Of these the reactor accidents which may lead to serious consequences for the crew and the environment are considered further. These are reactivity accidents and loss of coolant accidents. In addition the long term risks of sunken nuclear ships and sea disposed reactor compartments etc. are also discussed. Based on available accident data an attempt is made to estimate the probability of serious nuclear ship accidents. (au)
International Nuclear Information System (INIS)
Wang Qing; Hou Yu-Long; Jing Jian; Long Zheng-Wen
2014-01-01
In this paper, we study symmetrical properties of two-dimensional (2D) screened Dirac Hydrogen atom and isotropic harmonic oscillator with scalar and vector potentials of equal magnitude (SVPEM). We find that it is possible for both cases to preserve so(3) and su(2) dynamical symmetries provided certain conditions are satisfied. Interestingly, the conditions for preserving these dynamical symmetries are exactly the same as non-relativistic screened Hydrogen atom and screened isotropic oscillator preserving their dynamical symmetries. Some intuitive explanations are proposed. (general)
International Nuclear Information System (INIS)
Xu, Chang; Li, Bao-An; Chen, Lie-Wen
2014-01-01
In this contribution, we review the most important physics presented originally in our recent publications. Some new analyses, insights and perspectives are also provided. We showed recently that the symmetry energy E sym (ρ) and its density slope L(ρ) at an arbitrary density ρ can be expressed analytically in terms of the magnitude and momentum dependence of the single-nucleon potentials using the Hugenholtz-Van Hove (HVH) theorem. These relationships provide new insights about the fundamental physics governing the density dependence of nuclear symmetry energy. Using the isospin and momentum (k) dependent MDI interaction as an example, the contribution of different terms in the single-nucleon potential to the E sym (ρ) and L(ρ) are analyzed in detail at different densities. It is shown that the behavior of E sym is mainly determined by the first-order symmetry potential U sym,1 (ρ, k) of the single-nucleon potential. The density slope L(ρ) depends not only on the first-order symmetry potential U sym,1 (ρ, k) but also on the second-order one U sym,2 (ρ, k). Both the U sym,1 (ρ, k) and U sym,2 (ρ, k) at normal density ρ 0 are constrained by the isospin- and momentum-dependent nucleon optical potential extracted from the available nucleon-nucleus scattering data. The U sym,2 (ρ, k) especially at high density and momentum affects significantly the L(ρ), but it is theoretically poorly understood and currently there is almost no experimental constraints known. (orig.)
Effective potential and spontaneous symmetry breaking in the noncommutative φ6 model
International Nuclear Information System (INIS)
Barbosa, G.D.
2004-01-01
We study the conditions for spontaneous symmetry breaking of the (2+1)-dimensional noncommutative φ 6 model in the small-θ limit. In this regime, considering the model as a cutoff theory, it is reasonable to assume translational invariance as a property of the vacuum state and study the conditions for spontaneous symmetry breaking by an effective potential analysis. An investigation of up to the two-loop level reveals that noncommutative effects can modify drastically the shape of the effective potential. Under reasonable conditions, the nonplanar sector of the theory can become dominant and induce symmetry breaking for values of the mass and coupling constants not reached by the commutative counterpart
Neutron Skin of 208Pb, Nuclear Symmetry Energy, and the Parity Radius Experiment
International Nuclear Information System (INIS)
Roca-Maza, X.; Centelles, M.; Vinas, X.; Warda, M.
2011-01-01
A precise determination of the neutron skin Δr np of a heavy nucleus sets a basic constraint on the nuclear symmetry energy (Δr np is the difference of the neutron and proton rms radii of the nucleus). The parity radius experiment (PREX) may achieve it by electroweak parity-violating electron scattering (PVES) on 208 Pb. We investigate PVES in nuclear mean field approach to allow the accurate extraction of Δr np of 208 Pb from the parity-violating asymmetry A PV probed in the experiment. We demonstrate a high linear correlation between A PV and Δr np in successful mean field forces as the best means to constrain the neutron skin of 208 Pb from PREX, without assumptions on the neutron density shape. Continuation of the experiment with higher precision in A PV is motivated since the present method can support it to constrain the density slope of the nuclear symmetry energy to new accuracy.
Circumstantial Evidence for a Soft Nuclear Symmetry Energy at Suprasaturation Densities
International Nuclear Information System (INIS)
Xiao Zhigang; Zhang Ming; Li Baoan; Chen Liewen; Yong Gaochan
2009-01-01
Within an isospin- and momentum-dependent hadronic transport model, it is shown that the recent FOPI data on the π - /π + ratio in central heavy-ion collisions at SIS/GSI energies [Willy Reisdorf et al., Nucl. Phys. A 781, 459 (2007)] provide circumstantial evidence suggesting a rather soft nuclear symmetry energy E sym (ρ) at ρ≥2ρ 0 compared to the Akmal-Pandharipande-Ravenhall prediction. Some astrophysical implications and the need for further experimental confirmations are discussed
Nuclear potentials due to pion exchange
International Nuclear Information System (INIS)
Robillota, M.R.
1984-01-01
The two, three and four nucleon potentials due to the exchange of pions can be accurately calculated by means of chiral symmetry. The comparison of the dynamical content of these potentials allow us to understand the geometrical origin of the hierarchy existing among them. (Author) [pt
Radiative symmetry breaking at the Fermi scale and flat potential at the Planck scale
Hashimoto, Michio; Iso, Satoshi; Orikasa, Yuta
2014-01-01
We investigate a possibility of the "flatland scenario," in which the electroweak gauge symmetry is radiatively broken via the Coleman-Weinberg mechanism starting from a completely flat Higgs potential at the Planck scale. We show that the flatland scenario is realizable only when an inequality K<1 among the coefficients of the β functions is satisfied. We show several models satisfying the condition.
Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei
International Nuclear Information System (INIS)
Chen Liewen; Ko Che Ming; Xu Jun; Li Baoan
2010-01-01
Expressing explicitly the parameters of the standard Skyrme interaction in terms of the macroscopic properties of asymmetric nuclear matter, we show in the Skyrme-Hartree-Fock approach that unambiguous correlations exist between observables of finite nuclei and nuclear matter properties. We find that existing data on neutron skin thickness Δr np of Sn isotopes give an important constraint on the symmetry energy E sym (ρ 0 ) and its density slope L at saturation density ρ 0 . Combining these constraints with those from recent analyses of isospin diffusion and the double neutron/proton ratio in heavy-ion collisions at intermediate energies leads to a more stringent limit on L approximately independent of E sym (ρ 0 ). The implication of these new constraints on the Δr np of 208 Pb as well as the core-crust transition density and pressure in neutron stars is discussed.
Towards an understanding of the nuclear potential
International Nuclear Information System (INIS)
Richards, D.G.
1989-01-01
The formalism for investigating the anti Qqanti Qq system on the lattice is constructed. We describe how the model may be used to study the nuclear potential, and present some preliminary results on the range of the nuclear force. (orig.)
P-odd component of time-reversal symmetry violation. Manifestation in nuclear processes
International Nuclear Information System (INIS)
Tchuvil'sky, Yu.M.
2004-01-01
Full text: The problem of fundamental symmetries and the effects breaking them is one of the basic challenges of modern physics. There are grounds to assume that the major contributor to these effects is placed beyond the standard model. Nuclear processes are usable tests on T-even P-odd, T-odd P-even, and T-odd P-odd effects. The first type of them is rather well-studied. The possibilities to measure an effect of the second type seem to be poor in the discussed processes. At the same time search for time-reversal P-odd (PT-) symmetry violation offers promise for experimental investigation due to existence of nuclear enhancement effects analogous to T-even P-odd ones. An investigation of the effect in nuclear processes is considered as a promising source of the information which is complementary to that obtained in the framework of K- and B-meson experiments and measurements of the electric dipole moments of elementary particles and atoms. The matter is that the amplitudes specific for PT-symmetry violation in NN-interaction (isovector meson exchange amplitude for example) turn out to be essential or even dominating in the discussed case. In the present talk the results of the analysis of capability of the wide range of experimental schemes are presented. This analysis demonstrates the significant advantage of the scheme based on the measurement of linear polarization of gamma radiation of oriented (by an incident particle, or by a preceding alpha-decay, or by cryogenic means) sample. Indeed, the discussed approach, on the one hand, allows one to remove cumbersome coincident schemes and, on the other hand, the formalism of the approach is usually characterized by a relatively large spin factor in the relation connecting the correlation effect in a nucleus with the elementary amplitude. The estimations demonstrate that in appropriate cases the upper limit to the PT-violation effect of about 10 -3 of the observed P-odd effect in the same nucleus may be obtained. This
Parametric symmetries in exactly solvable real and PT symmetric complex potentials
Energy Technology Data Exchange (ETDEWEB)
Yadav, Rajesh Kumar, E-mail: rajeshastrophysics@gmail.com [Department of Physics, S. P. College, S K. M. University, Dumka 814101 (India); Khare, Avinash, E-mail: khare@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Bagchi, Bijan, E-mail: bbagchi123@gmail.com [Department of Physics, School of Natural Science, Shiv Nadar University, Greater Noida, UP 201314 (India); Kumari, Nisha, E-mail: nishaism0086@gmail.com; Mandal, Bhabani Prasad, E-mail: bhabani.mandal@gmail.com [Department of Physics, Banaras Hindu University, Varanasi 221005 (India)
2016-06-15
In this paper, we discuss the parametric symmetries in different exactly solvable systems characterized by real or complex PT symmetric potentials. We focus our attention on the conventional potentials such as the generalized Pöschl Teller (GPT), Scarf-I, and PT symmetric Scarf-II which are invariant under certain parametric transformations. The resulting set of potentials is shown to yield a completely different behavior of the bound state solutions. Further, the supersymmetric partner potentials acquire different forms under such parametric transformations leading to new sets of exactly solvable real and PT symmetric complex potentials. These potentials are also observed to be shape invariant (SI) in nature. We subsequently take up a study of the newly discovered rationally extended SI potentials, corresponding to the above mentioned conventional potentials, whose bound state solutions are associated with the exceptional orthogonal polynomials (EOPs). We discuss the transformations of the corresponding Casimir operator employing the properties of the so(2, 1) algebra.
The photino sector and a confining potential in a supersymmetric Lorentz-symmetry-violating model
Energy Technology Data Exchange (ETDEWEB)
Belich, H. [Universidade Federal do Espirito Santo, Departamento de Fisica e Quimica, Vitoria, ES (Brazil); Bernald, L.D.; Helayel-Neto, J.A. [Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, RJ (Brazil); Gaete, Patricio [Universidad Tecnica Federico Santa Maria, Departmento de Fisica and Centro Cientifico-Tecnologico de Valparaiso, Valparaiso (Chile)
2013-11-15
We study the spectrum of the minimal supersymmetric extension of the Carroll-Field-Jackiw model for Electrodynamics with a topological Chern-Simons-like Lorentz-symmetry violating term. We identify a number of independent background fermion condensates, work out the gaugino dispersion relation and propose a photonic effective action to consider aspects of confinement induced by the SUSY background fermion condensates, which also appear to signal Lorentz-symmetry violation in the photino sector of the action. Our calculations of the static potential are carried out within the framework of the gauge-invariant but path-dependent variables formalism which are alternative to the Wilson loop approach. Our results show that the interaction energy contains a linear term leading to the confinement of static probe charges. (orig.)
International Nuclear Information System (INIS)
Yong Gaochan; Li Baoan; Chen Liewen
2007-01-01
Within a transport model it is shown that the neutron/proton ratio of squeezed-out nucleons perpendicular to the reaction plane, especially at high transverse momenta, in heavy-ion reactions induced by high energy neutron-rich nuclei can be a useful tool for studying the high density behavior of the nuclear symmetry energy
International Nuclear Information System (INIS)
Wen, Dehua; Li, Baoan; Krastev, P.G.
2010-01-01
The frequencies and damping times of the axial w-mode oscillations of neutron stars are investigated using a nuclear equation of state (EOS) partially constrained by the available terrestrial laboratory data. It is found that the nuclear symmetry energy E sym (ρ), especially its high density behavior, plays an important role in determining both the eigen-frequencies and the damping times of these oscillations. (author)
Spin and Pseudospin Symmetries with Trigonometric Pöschl-Teller Potential including Tensor Coupling
Directory of Open Access Journals (Sweden)
M. Hamzavi
2013-01-01
Full Text Available We study approximate analytical solutions of the Dirac equation with the trigonometric Pöschl-Teller (tPT potential and a Coulomb-like tensor potential for arbitrary spin-orbit quantum number κ under the presence of exact spin and pseudospin ( p -spin symmetries. The bound state energy eigenvalues and the corresponding two-component wave functions of the Dirac particle are obtained using the parametric generalization of the Nikiforov-Uvarov (NU method. We show that tensor interaction removes degeneracies between spin and pseudospin doublets. The case of nonrelativistic limit is studied too.
Potential for nuclear terrorism: a discussion
International Nuclear Information System (INIS)
Kellen, K.
1987-01-01
Because there has never been an incident of nuclear terrorism, the author is reduced to informed speculation. The past cannot be used to extrapolate into the future. For terrorists as for nations, the domain of nuclear attack represents are unprecedented quantum leap, one that groups think carefully about. Terrorists will consider many factors, including the public climate, because they are not psychotics operating in a vacuum (though groups may include psychotic individuals). Rather, they are people involved in a reciprocal political and psychological relationship with the rest of the world. In reaching some assessment of the potential for nuclear terrorism, there is an immense number of variables to deal with, beginning with the many types of terrorists and terrorism, including nuclear. They can, however, look at individual terrorist groups - a their compositions, capabilities, motivations, and modus operandi - and reach some conclusions. The author first looks at the possible forms nuclear terrorism might take and at the severity of the consequences. A strict distinction must be made between nuclear terrorism where nuclear things are the means (for example, a nuclear device) and nuclear terrorism where nuclear things are the target (for example, nuclear power stations), or where they are both such as a nuclear weapon thrown at a nuclear power station. 2 tables
Chirally motivated K(-) nuclear potentials
Czech Academy of Sciences Publication Activity Database
Cieplý, Aleš; Friedman, E.; Gal, A.; Gazda, Daniel; Mareš, Jiří
2011-01-01
Roč. 702, č. 5 (2011), s. 402-407 ISSN 0370-2693 R&D Projects: GA ČR GA202/09/1441 Institutional research plan: CEZ:AV0Z10480505 Keywords : Kaon-baryon interactions * Mesic nuclei * Mesonic atoms Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.955, year: 2011
Energy Technology Data Exchange (ETDEWEB)
Khoa, Dao T.; Thang, Dang Ngoc [VINATOM, Institute for Nuclear Science and Technique, Hanoi (Viet Nam); Loc, Bui Minh [VINATOM, Institute for Nuclear Science and Technique, Hanoi (Viet Nam); University of Pedagogy, Ho Chi Minh City (Viet Nam)
2014-02-15
The Fermi transition (ΔL = ΔS = 0 and ΔT = 1) between the nuclear isobaric analog states (IAS), induced by the charge-exchange (p, n) or ({sup 3}He, t) reaction, can be considered as ''elastic'' scattering of proton or {sup 3}He by the isovector term of the optical potential (OP) that flips the projectile isospin. The accurately measured (p, n) or ({sup 3}He, t) scattering cross section to the IAS can be used, therefore, to probe the isospin dependence of the proton or {sup 3}He optical potential. Within the folding model, the isovector part of the OP is determined exclusively by the neutron-proton difference in the nuclear densities and the isospin dependence of the effective nucleon-nucleon (NN) interaction. Because the isovector coupling explicitly links the isovector part of the proton or {sup 3}He optical potential to the cross section of the charge-exchange (p, n) or ({sup 3}He, t) scattering to the IAS, the isospin dependence of the effective (in-medium) NN interaction can be well tested in the folding model analysis of these charge-exchange reactions. On the other hand, the same isospin- and density-dependent NN interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part (the nuclear symmetry energy). As a result, the fine-tuning of the isospin dependence of the effective NN interaction against the measured (p, n) or ({sup 3}He, t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. (orig.)
International Nuclear Information System (INIS)
Khoa, Dao T.; Thang, Dang Ngoc; Loc, Bui Minh
2014-01-01
The Fermi transition (ΔL = ΔS = 0 and ΔT = 1) between the nuclear isobaric analog states (IAS), induced by the charge-exchange (p, n) or ( 3 He, t) reaction, can be considered as ''elastic'' scattering of proton or 3 He by the isovector term of the optical potential (OP) that flips the projectile isospin. The accurately measured (p, n) or ( 3 He, t) scattering cross section to the IAS can be used, therefore, to probe the isospin dependence of the proton or 3 He optical potential. Within the folding model, the isovector part of the OP is determined exclusively by the neutron-proton difference in the nuclear densities and the isospin dependence of the effective nucleon-nucleon (NN) interaction. Because the isovector coupling explicitly links the isovector part of the proton or 3 He optical potential to the cross section of the charge-exchange (p, n) or ( 3 He, t) scattering to the IAS, the isospin dependence of the effective (in-medium) NN interaction can be well tested in the folding model analysis of these charge-exchange reactions. On the other hand, the same isospin- and density-dependent NN interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part (the nuclear symmetry energy). As a result, the fine-tuning of the isospin dependence of the effective NN interaction against the measured (p, n) or ( 3 He, t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. (orig.)
Radiative symmetry breaking from flat potential in various U(1)' models
Hashimoto, Michio; Iso, Satoshi; Orikasa, Yuta
2014-03-01
We investigate a radiative electroweak gauge symmetry breaking scenario via the Coleman-Weinberg mechanism starting from a completely flat Higgs potential at the Planck scale ("flatland scenario"). In our previous paper, we showed that the flatland scenario is possible only when an inequality K <1 among the coefficients of the β functions is satisfied. In this paper, we calculate the number K in various models with an extra U(1) gauge sector in addition to the standard model particles. We also show the renormalization group behaviors of a couple of the models as examples.
Symmetry Breaking of B2N((-, 0, +)): An Aspect of the Electric Potential and Atomic Charges.
Monajjemi, Majid; Bagheri, Samira; Moosavi, Matin S; Moradiyeh, Nahid; Zakeri, Mina; Attarikhasraghi, Naime; Saghayimarouf, Nastaran; Niyatzadeh, Ghorban; Shekarkhand, Marzie; Khalilimofrad, Mohammad S; Ahmadin, Hashem; Ahadi, Maryam
2015-12-03
In this study, the three forms of B2N((-, 0, +))-radical, anion and cation-have been compared in terms of electric potential and atomic charges, ESP, rather than the well-known cut of the potential energy surface (PES). We have realized that the double minimum of the BNB radical is related to the lack of the correct permutational symmetry of the wave function and charge distribution. The symmetry breaking (SB) for B2N((0, +)) exhibits energy barrier in the region of (5-150) cm(-1). The SB barrier goes through a dynamic change with no centrosymmetric form which depends on the wave function or charge distribution. In spite of A ˜ 2 Σ g + exited state, the B ˜ 2 ∏ g excited configuration contributes to the ground state ( B ˜ 2 ∏ g - X ˜ 2 Σ u + ) for forming radicals. The SB did not occur for the anion form (B2N((-))) in any electrostatic potential and charges distribution. Finally, we have modified the Columbic term of the Schrödinger equation to define the parameters "αα' and ββ'" in order to investigate the SBs subject.
Temperature effects on nuclear pseudospin symmetry in the Dirac-Hartree-Bogoliubov formalism
Lisboa, R.; Alberto, P.; Carlson, B. V.; Malheiro, M.
2017-01-01
We present finite temperature Dirac-Hartree-Bogoliubov (FTDHB) calculations for the tin isotope chain to study the dependence of pseudospin on the nuclear temperature. In the FTDHB calculation, the density dependence of the self-consistent relativistic mean fields, the pairing, and the vapor phase that takes into account the unbound nucleon states are considered self-consistently. The mean field potentials obtained in the FTDHB calculations are fit by Woods-Saxon (WS) potentials to examine ho...
Zhang, Yingxun; Coupland, D. D. S.; Danielewicz, P.; Li, Zhuxia; Liu, Hang; Lu, Fei; Lynch, W. G.; Tsang, M. B.
2012-02-01
We explore the influence of the in-medium nucleon-nucleon cross section, symmetry potential, and impact parameter on isospin sensitive observables in intermediate-energy heavy-ion collisions with the ImQMD05 code, a modified version of the quantum molecular dynamics model. At incident velocities above the Fermi velocity, we find that the density dependence of the symmetry potential plays a more important role on the double neutron-to-proton ratio DR(n/p) and the isospin transport ratio Ri than the in-medium nucleon-nucleon cross sections, provided that the latter are constrained to a fixed total NN collision rate. We also explore both DR(n/p) and Ri as a function of the impact parameter. Since the copious production of intermediate mass fragments is a distinguishing feature of intermediate-energy heavy-ion collisions, we examine the isospin transport ratios constructed from different groups of fragments. We find that the values of the isospin transport ratios for projectile rapidity fragments with Z⩾20 are greater than those constructed from the entire projectile rapidity source. We believe experimental investigations of this phenomenon can be performed. These may provide significant tests of fragmentation time scales predicted by ImQMD calculations.
Scalar potentials, propagators and global symmetries in AdS/CFT
Bajc, Borut
2013-01-01
We study the transition of a scalar field in a fixed $AdS_{d+1}$ background between an extremum and a minimum of a potential. We first prove that two conditions must be met for the solution to exist. First, the potential involved cannot be generic, i.e. a fine-tuning of their parameters is mandatory. Second, at least in some region its second derivative must have a negative upper limit which depends only on the dimensionality $d$. We then calculate the boundary propagator for small momenta in two different ways: first in a WKB approximation, and second with the usual matching method, generalizing the known calculation to arbitrary order. Finally, we study a system with spontaneously broken non-Abelian global symmetry, and show in the holographic language why the Goldstone modes appear.
On the nuclear interaction potential in the heavy ion reactions
International Nuclear Information System (INIS)
Molina, Kh.L.; Shitikova, K.V.
1980-01-01
The interaction potential of heavy ions 4 He, 6 Li, 12 C and 16 O is constructed in the folding model. The density of nuclear matter distribution for these nuclei is calculated in the framework of the hyperspherical function method. For the calculation of the folding potential the Skyrme two-body nucleon-nucleon forces were employed. The influence of several effects on the results of calculation is studied. Density dependence of the nucleon-nucleon interaction, dependence of the folding potential on the number of particles, the potential symmetry in the interaction of identical and different particles and the possibility of observing the monopole-resonance in the ion inelastic scattering are investigated. The investigations showed that the higher is the nuclear excitation energy the wider and shallower is the form of a potential. Non-diagonal matrix elements are not negligible. Nevertheless, in order to estimate the degree of the monopole giant resonance manifestation in the heavy ion collisions, it is necessary to carry out the direct calculation of inelastic collision cross-section for two heavy particles including the calculation over this channel into the scheme
International Nuclear Information System (INIS)
Suparmi, A.; Cari, C.; Deta, U. A.
2014-01-01
The bound state solutions of Dirac equations for a trigonometric Scarf potential with a new tensor potential under spin and pseudospin symmetry limits are investigated using Romanovski polynomials. The proposed new tensor potential is inspired by superpotential form in supersymmetric (SUSY) quantum mechanics. The Dirac equations with trigonometric Scarf potential coupled by a new tensor potential for the pseudospin and spin symmetries reduce to Schrödinger-type equations with a shape invariant potential since the proposed new tensor potential is similar to the superpotential of trigonometric Scarf potential. The relativistic wave functions are exactly obtained in terms of Romanovski polynomials and the relativistic energy equations are also exactly obtained in the approximation scheme of centrifugal term. The new tensor potential removes the degeneracies both for pseudospin and spin symmetries. (general)
Yurchenko, Sergei N; Yachmenev, Andrey; Ovsyannikov, Roman I
2017-09-12
We present a general, numerically motivated approach to the construction of symmetry-adapted basis functions for solving ro-vibrational Schrödinger equations. The approach is based on the property of the Hamiltonian operator to commute with the complete set of symmetry operators and, hence, to reflect the symmetry of the system. The symmetry-adapted ro-vibrational basis set is constructed numerically by solving a set of reduced vibrational eigenvalue problems. In order to assign the irreducible representations associated with these eigenfunctions, their symmetry properties are probed on a grid of molecular geometries with the corresponding symmetry operations. The transformation matrices are reconstructed by solving overdetermined systems of linear equations related to the transformation properties of the corresponding wave functions on the grid. Our method is implemented in the variational approach TROVE and has been successfully applied to many problems covering the most important molecular symmetry groups. Several examples are used to illustrate the procedure, which can be easily applied to different types of coordinates, basis sets, and molecular systems.
Interatomic potentials for materials of nuclear interest
International Nuclear Information System (INIS)
Fernandez, Julian R.; Monti, Ana M.; Pasianot, Roberto C.; Simonelli, G.
2007-01-01
Procedures to develop embedded atom method (EAM) interatomic potentials are described, with foreseeable applications in nuclear materials. Their reliability is shown by evaluating relevant properties. The studied materials are Nb, Zr and U. The first two were then used to develop an inter species potential for the Zr-Nb binary system. In this sense, the Fe-Cu system was also studied starting from Fe and Cu potentials extracted from the literature. (author) [es
On radii of nuclear potential and density
International Nuclear Information System (INIS)
Bal'butsev, E.B.; Mikhajlov, I.N.
1975-01-01
The Saxon-Woods potential is widely used as an average field in different nuclear models: upsilon(r)=-upsilonsub(0)parameters: upsilonsub(0) is the well depth, Rsub(v) is the well width, a is the diffusivity of the potential edge. The potential parameters should be determined from the data on the nuclear matter distribution. The data available is in agreement with the formula for density: rho(r)=rhosub(0)same sense as Rsub(v), a. The experimental data show that Rsub(v) by 1 Fermi exceed Rsub(rho) approximately. There exist some suggestions that it caused by the finiteness of the radius of action of nuclear forces. It is noted that finiteness of radius of action of forces is a sufficient condition for the presence of this effect. A model is considered in which the matter is limited with a plane surface, so that the density depends only on a single spatial variable normal to the boundary of matter. As is shown by the results, the radius of nuclear potential exceeds that of the volume of the nuclear matter by 0.6 Fermi approximately. The mechanism of this phenomenon takes its origin from a quantum-mechanical effect of turning the wave functions into zero near the infinitely high wall and from their considerable decreasing near the wall of a finite height
Voisin, Claire
1999-01-01
This is the English translation of Professor Voisin's book reflecting the discovery of the mirror symmetry phenomenon. The first chapter is devoted to the geometry of Calabi-Yau manifolds, and the second describes, as motivation, the ideas from quantum field theory that led to the discovery of mirror symmetry. The other chapters deal with more specialized aspects of the subject: the work of Candelas, de la Ossa, Greene, and Parkes, based on the fact that under the mirror symmetry hypothesis, the variation of Hodge structure of a Calabi-Yau threefold determines the Gromov-Witten invariants of its mirror; Batyrev's construction, which exhibits the mirror symmetry phenomenon between hypersurfaces of toric Fano varieties, after a combinatorial classification of the latter; the mathematical construction of the Gromov-Witten potential, and the proof of its crucial property (that it satisfies the WDVV equation), which makes it possible to construct a flat connection underlying a variation of Hodge structure in the ...
Level density from realistic nuclear potentials
International Nuclear Information System (INIS)
Calboreanu, A.
2006-01-01
Nuclear level density of some nuclei is calculated using a realistic set of single particle states (sps). These states are derived from the parameterization of nuclear potentials that describe the observed sps over a large number of nuclei. This approach has the advantage that one can infer level density for nuclei that are inaccessible for a direct study, but are very important in astrophysical processes such as those close to the drip lines. Level densities at high excitation energies are very sensitive to the actual set of sps. The fact that the sps spectrum is finite has extraordinary consequences upon nuclear reaction yields due to the leveling-off of the level density at extremely high excitation energies wrongly attributed so far to other nuclear effects. Single-particle level density parameter a parameter is extracted by fitting the calculated densities to the standard Bethe formula
Directory of Open Access Journals (Sweden)
Edward Chia-Cheng Lai
Full Text Available PURPOSE: Previous studies have demonstrated sulpiride to be significantly more effective than haloperidol, risperidone and olanzapine in schizophrenic treatment; however, only limited information is available on the potential risks associated with sulpiride treatment. This study attempts to provide information on the potential risks of sulpiride treatment of schizophrenia, especially with regard to unexpected adverse effects. MATERIALS AND METHODS: Patients with schizophrenia aged 18 and older, newly prescribed with a single antipsychotic medication from the National Health Insurance Research Database of Taiwan in the period from 2003 to 2010 were included. A within-subject comparison method, prescription sequence symmetry analysis (PSSA was employed to efficiently identify potential causal relationships while controlling for potential selection bias. RESULTS: A total of 5,750 patients, with a mean age of 39, approximately half of whom were male, constituted the study cohort. The PSSA found that sulpiride was associated with EPS (adjusted SR, 1.73; 95% CI, 1.46-2.06 and hyperprolactinemia (12.04; 1.59-91.2. In comparison, EPS caused by haloperidol has a magnitude of 1.99 when analyzed with PSSA, and hyperprolactinemia caused by amisulpride has a magnitude of 8.05, respectively. Another finding was the unexpected increase in the use of stomatological corticosteroids, emollient laxatives, dermatological preparations of corticosteroids, quinolone antibacterials, and topical products for joint and muscular pain, after initiation of sulpiride treatment. CONCLUSIONS: We found sulpiride to be associated with an increased risk of EPS and hyperprolactinemia, and the potential risk could be as high as that induced by haloperidol and amisulpride, respectively. Additionally, our study provides grounds for future investigations into the associations between sulpiride and the increased use of additional drugs for managing adverse effects, including
Control of the symmetry breaking in double-well potentials by the resonant nonlinearity management
International Nuclear Information System (INIS)
Nistazakis, H. E.; Frantzeskakis, D. J.; Malomed, B. A.; Kevrekidis, P. G.
2011-01-01
We introduce a one-dimensional model of Bose-Einstein condensates (BECs), combining the double-well potential, which is a usual setting for the onset of spontaneous-symmetry-breaking (SSB) effects, and time-periodic modulation of the nonlinearity, which may be implemented by means of the Feshbach-resonance-management (FRM) technique. Both cases of the nonlinearity that is repulsive or attractive on the average are considered. In the former case, the main effect produced by the application of the FRM is spontaneous self-trapping of the condensate in either of the two potential wells in parameter regimes where it would remain untrapped in the absence of the management. In the weakly nonlinear regime, the frequency of intrinsic oscillations in the FRM-induced trapped state is very close to half the FRM frequency, suggesting that the effect is accounted for by a parametric resonance. In the case of the attractive nonlinearity, the FRM-induced effect is the opposite, i.e., enforced detrapping of a state which is self-trapped in its unmanaged form. In the latter case, the frequency of oscillations of the untrapped mode is close to a quarter of the driving frequency, suggesting that a higher-order parametric resonance may account for this effect.
Influence of the nuclear symmetry energy on the collective flows of charged pions
Gao, Yuan; Yong, Gao-Chan; Zhang, Lei; Zuo, Wei
2018-01-01
Based on the isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, we studied charged pion transverse and elliptic flows in semicentral 197Au+197Au collisions at 600 MeV/nucleon. It is found that π+-π- differential transverse flow and the difference of π+ and π- transverse flows almost show no effects of the symmetry energy. Their corresponding elliptic flows are largely affected by the symmetry energy, especially at high transverse momenta. The isospin-dependent pion elliptic flow at high transverse momenta thus provides a promising way to probe the high-density behavior of the symmetry energy in heavy-ion collisions at the Facility for Antiproton and Ion Research (FAIR) at GSI, Darmstadt or at the Cooling Storage Ring (CSR) at HIRFL, Lanzhou.
Noble gas, a potential nuclear proliferation indicator
International Nuclear Information System (INIS)
Chapman, T.C.
1993-01-01
In the post-Cold War era, it appears that nuclear proliferation will be a continuing problem. At least one reliable technique to detect nuclear activities is needed to deter potential proliferators. This paper proposes a candidate technique for detection. Early efforts to measure nuclear fuel performance resulted in the consideration of a variety of potential techniques. In 1965, Maeck proposed determination of nuclear fuel burnup based on the ratio of two stable fission product isotopes of the same element. Maeck proposed using three ratios: 84 Kr/ 83 Kr, 132 Xe/ 131 Xe, and 144 Nd/ 143 Nd. More recent work includes useful application of krypton and xenon isotope correlation techniques to safeguards at nuclear fuel reprocessing facilities. The safeguards application requires very precise measurement of the fission product isotopes, detailed fuel exposure history, and knowledge of the neutron spectrum. Meeting all these requirements is extremely difficult and requires carefully controlled conditions. The most likely scenario for a proliferator to produce nuclear material suitable for weapons applications is reprocessing of reactor fuel to recover the plutonium. Since useful amounts of plutonium are produced in all uranium-fueled reactors, reprocessing the reactor fuel would be much easier and less expensive than mining and enriching uranium to weapons-grade material. Reprocessing nuclear reactor fuel releases the noble gases krypton and xenon from the fuel. Because capture of the noble gases is difficult, expensive, and produces a radiation hazard, the gases will normally be released during reprocessing. These factors provide the basis for this proposed technique of detecting proliferators
Lim, Yu Rim; Park, Seong Jun; Song, Sanggeun; Yang, Gil-Suk; Yoon, Young-Gui; Kim, Ji-Hyun; Sung, Jaeyoung
2014-06-01
Liquid helium does not obey the Gibbs fluctuation-compressibility relation, which was noted more than six decades ago. However, still missing is a clear explanation of the reason for the deviation or the correct fluctuation-compressibility relation for the quantum liquid. Here we present the fluctuation-compressibility relation valid for any grand canonical system. Our result shows that the deviation from the Gibbs formula arises from a nonextensive part of thermodynamic potentials. The particle-exchange symmetry of many-body wave function of a strongly degenerate quantum gas is related to the thermodynamic extensivity of the system; a Bose gas does not always obey the Gibbs formula, while a Fermi gas does. Our fluctuation-compressibility relation works for classical systems as well as quantum systems. This work demonstrates that the application range of the Gibbs-Boltzmann statistical thermodynamics can be extended to encompass nonextensive open systems without introducing any postulate other than the principle of equal a priori probability.
International Nuclear Information System (INIS)
Eshghi, M.; Ikhdair, S. M.
2014-01-01
A relativistic Mie-type potential for spin-1/2 particles is studied. The Dirac Hamiltonian contains a scalar S(r) and a vector V(r) Mie-type potential in the radial coordinates, as well as a tensor potential U(r) in the form of Coulomb potential. In the pseudospin (p-spin) symmetry setting Σ = C ps and Δ = V(r), an analytical solution for exact bound states of the corresponding Dirac equation is found. The eigenenergies and normalized wave functions are presented and particular cases are discussed with any arbitrary spin—orbit coupling number κ. Special attention is devoted to the case Σ = 0 for which p-spin symmetry is exact. The Laplace transform approach (LTA) is used in our calculations. Some numerical results are obtained and compared with those of other methods. (general)
International Nuclear Information System (INIS)
Wen Dehua; Li Baoan; Krastev, Plamen G.
2009-01-01
The eigenfrequencies of the axial w-modes of oscillating neutron stars are studied using the continued fraction method with an equation of state (EOS) partially constrained by the recent terrestrial nuclear laboratory data. It is shown that the density dependence of the nuclear symmetry energy E sym (ρ) affects significantly both the frequencies and the damping times of these modes. Besides confirming the previously found universal behavior of the mass-scaled eigenfrequencies as functions of the compactness of neutron stars, we explored several alternative universal scaling functions. Moreover, the w II -mode is found to exist only for neutron stars having a compactness of M/R≥0.1078 independent of the EOS used.
Directory of Open Access Journals (Sweden)
He Xiao-Tao
2016-01-01
Full Text Available A thorough understanding of properties of neutron stars requires both a reliable knowledge of the equation of state (EOS of super-dense nuclear matter and the strong-field gravity theories simultaneously. To provide information that may help break this EOS-gravity degeneracy, we investigate effects of nuclear symmetry energy on the gravitational binding energy of neutron stars within GR and the scalar-tensor subset of alternative gravity models. We focus on effects of the slope L of nuclear symmetry energy at saturation density and the high-density behavior of nuclear symmetry energy. We find that the variation of either the density slope L or the high-density behavior of nuclear symmetry energy leads to large changes in the binding energy of neutron stars. The difference in predictions using the GR and the scalar-tensor theory appears only for massive neutron stars, and even then is significantly smaller than the difference resulting from variations in the symmetry energy.
Yong, Gao-Chan; Li, Bao-An
2017-12-01
Within an isospin- and momentum-dependent transport model for nuclear reactions at intermediate energies, we investigate the interplay of the nucleon-nucleon short-range correlations (SRCs) and nuclear symmetry energy Esym(ρ ) on hard-photon spectra in collisions of several Ca isotopes on 112Sn and 124Sn targets at a beam energy of 45 MeV/nucleon. It is found that over the whole spectra of hard photons studied, effects of the SRCs overwhelm those owing to the Esym(ρ ) . The energetic photons come mostly from the high-momentum tails (HMTs) of single-nucleon momentum distributions in the target and projectile. Within the neutron-proton dominance model of SRCs based on the consideration that the tensor force acts mostly in the isosinglet and spin-triplet nucleon-nucleon interaction channel, there are equal numbers of neutrons and protons, thus a zero isospin asymmetry in the HMTs. Therefore, experimental measurements of the energetic photons from heavy-ion collisions at Fermi energies have the great potential to help us better understand the nature of SRCs without any appreciable influence by the uncertain Esym(ρ ) . These measurements will be complementary to but also have some advantages over the ongoing and planned experiments using hadronic messengers from reactions induced by high-energy electrons or protons. Because the underlying physics of SRCs and Esym(ρ ) are closely correlated, a better understanding of the SRCs will, in turn, help constrain the nuclear symmetry energy more precisely in a broad density range.
Double beta decay, neutrino physics, nuclear structure and isospin and spin-isospin symmetries
International Nuclear Information System (INIS)
Krmpotic, F.
1989-12-01
Prominent features of the double beta decay processes are reviewed. Emphasis is placed on the neutrino masses and the quasiparticle random phase approximation (GRPA). The suppression mechanism for the ββ-decay transition rates, proposed by Vogel and Zirnbauer, is found to be closely related to the restoration of SU(4) symmetry. It is suggested that the extreme sensitivity of the ββ-decay amplitude on the proton-neutron coupling is a consequence of the explicit violation of the SU(4) symmetry and therefore an artifact of the model. A prescription is given for fixing this interaction strength within the GRPA itself, which in this way acquires predicting power on both single and double β-decay lifetimes. (author) [pt
Analytic extension of the nuclear algebraic potential
Energy Technology Data Exchange (ETDEWEB)
Lichtenthaeler, R. (Departamento de Fisica Nuclear, Laboratorio do Pelletron, Universidade de Sao Paulo, Caixa Postal 20516, 01452-990 Sao Paulo, Sao Paulo (Brazil)); Gomes, L.C. (Grupo de Fisica Nuclear Teorica e Fenomenologia de Particulas Elementares Instituto de Fisica Universidade de Sao Paulo, Caixa Postal 20516, 01498-970 Sao Paulo, Sao Paulo (Brazil))
1994-12-01
An analytic extension of the nuclear algebraic potential in the complex energy and angular momentum planes is discussed and an approximation for the algebraic potential in agreement with the known analytic properties of the [ital S]-matrix is proposed. The invariance of the energy spectrum of the Coulomb part of the interaction is established. The results are applied to the Regge pole analysis of the [sup 12]C+[sup 24]Mg elastic collision at [ital E][sub [ital l][ital a][ital b
Power spectrum of nuclear spectra with missing levels and mixed symmetries
Energy Technology Data Exchange (ETDEWEB)
Molina, R.A. [Max-Planck-Institut fuer Physik Komplexer Systeme, Noethnitzer Str. 38, D-01187 Dresden (Germany) and Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain)]. E-mail: molina@iem.cfmac.csic.es; Retamosa, J. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Munoz, L. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Relano, A. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain); Faleiro, E. [Departamento de Fisica Aplicada, Universidad Politecnica de Madrid, E-28012 (Spain)
2007-01-04
Sequences of energy levels in nuclei are often plagued with missing levels whose number and position are unknown. It is also quite usual that all the quantum numbers of certain levels cannot be experimentally determined, and thus levels of different symmetries are mixed in the same sequence. The analysis of these imperfect spectra (from the point of view of spectral statistics) is unavoidable if one wants to extract some statistical information. The power spectrum of the {delta}{sub q} statistic has emerged in recent years as an important tool for the study of quantum chaos and spectral statistics. We derive analytical expressions for the observed power spectrum in terms of the fraction of observed levels and the number of mixed sequences. These expressions are tested with large shell model spectra simulating realistic experimental situations. A good estimation of the number of mixed symmetries and the fraction of missing levels is obtained by means of a least-squares fit in a wide set of different situations.
International Nuclear Information System (INIS)
Zhang Ming; Xiao Zhigang; Li Baoan; Chen Liewen; Yong Gaochan; Zhu Shengjiang
2010-01-01
Based on the isospin-and momentum-dependent hadronic transport model IBUU04, we have investigated the π - /π + ratio in the following three reactions: 48 Ca+ 48 Ca, 124 Sn + 124 Sn and 197 Au + 197 Au with nearly the same isospin asymmetry but different masses, at the bombarding energies from 0.25 to 0.6 AGeV. It is shown that the sensitivity of probing the E sym (ρ) with π - /π + increases with increasing the system size or decreasing the beam energy, showing a correlation to the degree of isospin fractionation. Therefore, with a given isospin asymmetry, heavier system at energies near the pion threshold is preferential to study the behavior of nuclear symmetry energy at supra-saturation densities.
Potential criminal adversaries of nuclear programs: a portrait
Energy Technology Data Exchange (ETDEWEB)
Jenkins, B.M.
1980-07-01
This paper examines the possibility that terrorists or other kinds of criminals might attempt to seize or sabotage a nuclear facility, steal nuclear material, or carry out other criminal activities in the nuclear domain which has created special problems for the security of nuclear programs. This paper analyzes the potential threat. Our tasks was to describe the potential criminal adversary, or rather the spectrum of potential adversaries who conceivably might carry out malevolent criminal actions against nuclear programs and facilities. We were concerned with both the motivations as well as the material and operational capabilities likely to be displayed by various categories of potential nuclear adversaries.
Chubb, Scott
2003-03-01
Three, Key, Unanswered Questions posed by LENR's are: 1. How do we explain the lack of high energy particles (HEP's)? 2. Can we understand and prioritize the way coupling can occur between nuclear- and atomic- lengthscales, and 3. What are the roles of Surface-Like (SL), as opposed to Bulk-Like (BL), processes in triggering nuclear phenomena. One important source of confusion associated with each of these questions is the common perception that the quantum mechanical phases of different particles are not correlated with each other. When the momenta p of interacting particles is large, and reactions occur rapidly (between HEP's, for example), this is a valid assumption. But when the relative difference in p becomes vanishingly small, between one charge, and many others, as a result of implicit electromagnetic coupling, each charge can share a common phase, relative to the others, modulo 2nπ, where n is an integer, even when outside forces are introduced. The associated forms of broken gauge symmetry, distinguish BL from SL phenomena, at room temperature, also explain super- and normal- conductivity in solids, and can be used to address the Three, Key, Unanswered Questions posed by LENR's.
On the Relativistic Origin of Pseudo spin Symmetry in Nuclei
International Nuclear Information System (INIS)
Leviatan, A.
1998-01-01
We review the concept of pseudo spin symmetry and its role in nuclear spectroscopy. We survey the attempts to arrive at a microscopic understanding of this symmetry. In particular, we show that pseudo spin symmetry in nuclei could arise from nucleons moving in a relativistic mean field which has an attractive scalar (Vs) and repulsive vector (Vv) potential nearly equal in magnitude but opposite in sign. We show that the generators of pseudo spin symmetry are the non-relativistic limit of the generators of an SU(2) symmetry which leaves invariant the Dirac Hamiltonian with Vs 2= -Vv. Furthermore within this framework, we demonstrate that this symmetry may be approximately conserved for realistic scalar and vector potentials
Symmetry-improved 2PI approach to the Goldstone-boson IR problem of the SM effective potential
Directory of Open Access Journals (Sweden)
Apostolos Pilaftsis
2016-05-01
Full Text Available The effective potential of the Standard Model (SM, from three loop order and higher, suffers from infrared (IR divergences arising from quantum effects due to massless would-be Goldstone bosons associated with the longitudinal polarizations of the W± and Z bosons. Such IR pathologies also hinder accurate evaluation of the two-loop threshold corrections to electroweak quantities, such as the vacuum expectation value of the Higgs field. However, these divergences are an artifact of perturbation theory, and therefore need to be consistently resummed in order to obtain an IR-safe effective potential. The so-called Two-Particle-Irreducible (2PI effective action provides a rigorous framework to consistently perform such resummations, without the need to resort to ad hoc subtractions or running into the risk of over-counting contributions. By considering the recently proposed symmetry-improved 2PI formalism, we address the problem of the Goldstone-boson IR divergences of the SM effective potential in the gaugeless limit of the theory. In the same limit, we evaluate the IR-safe symmetry-improved 2PI effective potential, after taking into account quantum loops of chiral fermions, as well as the renormalization of spurious custodially breaking effects triggered by fermionic Yukawa interactions. Finally, we compare our results with those obtained with other methods presented in the literature.
International Nuclear Information System (INIS)
Haxton, W.
1990-01-01
This report discusses research in nuclear physics. Topics covered in this paper are: symmetry principles; nuclear astrophysics; nuclear structure; quark-gluon plasma; quantum chromodynamics; symmetry breaking; nuclear deformation; and cold fusion
Nuclear desalting potential for developing countries
International Nuclear Information System (INIS)
1969-01-01
Nuclear power, having proved its success in large units, now poses problems for application in developing countries. Possible solutions for electricity supply, desalting systems and agricultural development are suggested by Joseph R. Wilson, of the Agency's Division of Nuclear Power and Reactors. His article is adapted from a lecture to students in Switzerland. (author)
International Nuclear Information System (INIS)
Ikhdair Sameer M; Hamzavi Majid
2013-01-01
Approximate analytical bound-state solutions of the Dirac particle in the fields of attractive and repulsive Rosen—Morse (RM) potentials including the Coulomb-like tensor (CLT) potential are obtained for arbitrary spin-orbit quantum number κ. The Pekeris approximation is used to deal with the spin-orbit coupling terms κ (κ± 1)r −2 . In the presence of exact spin and pseudospin (p-spin) symmetries, the energy eigenvalues and the corresponding normalized two-component wave functions are found by using the parametric generalization of the Nikiforov—Uvarov (NU) method. The numerical results show that the CLT interaction removes degeneracies between the spin and p-spin state doublets. (general)
Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces
DEFF Research Database (Denmark)
Hall, B.; Deumens, E.; Ohrn, Y.
2014-01-01
A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...
Realizing the potential of nuclear energy
International Nuclear Information System (INIS)
Walske, C.
1982-01-01
The future of nuclear power, just as the future of America, can be viewed with optimism. There is hope in America's record of overcoming obstacles, but growth is essential for that hope to be realized. Despite the downturn in energy demand made possible by conservation, we will need a 35% growth in total energy for new workers and production. Electricity generated by nuclear or coal can make US production more cost-competitive, and it can power mass-transit systems, electric heat pumps, and communications and information systems. Changes in electricity and gross national product (GNP) have been more closely in step since 1973 than have total energy and GNP. The nuclear power units now under construction will add 80,000 megawatts to the 56,000 now on line. It is important to note that, while utilities are cancelling plans for nuclear plants, they aren't ordering new coal plants, which shows the impact of the high cost of money. Interest rates must come down and public-relations efforts to sell electricity must improve to change the situation. Although capital shortages are real, waste disposal is a problem of perception that was politically induced because the government failed to provide a demonstration of safety as the French are doing. Streamlined regulatory and insurance procedures can help to justify optimism in the nuclear option. 4 figures
In-Medium Kaon Potential and Nuclear Equation of State Measured in Nucleus–Nucleus Collisions
International Nuclear Information System (INIS)
Srisawad, P.; Suksri, A.; Harfield, A.; Limphirat, A.; Yan, Y.; Zheng, Y. M.
2013-01-01
The kaon production in heavy ion collisions at intermediate energies provides a sensitive probe to study the in-medium properties and nuclear equation of state of hadrons. Properties of kaons in dense hadronic matter are important for a better understanding of both, the possible restoration of chiral symmetry in dense hadronic matter and the properties of nuclear matter at high densities. We investigated the in-medium kaon potential and nuclear equation of state by transverse mass spectra of K + mesons in heavy ion collisions. We use quantum molecular dynamics (QMD) models based on covariant kaon dynamics to simulate 58 28 Ni+ 58 28 Ni collisions at 1.93 A GeV, to analyze the transverse mass spectra of K + . Calculated results with a repulsive in-medium K + N potential can reasonably describe the features of KaoS data. They also shown that the transverse mass spectrum of K + mesons is a sensitive observable to probe the kaon in-medium potential in dense nuclear matter. (author)
Wei, Gao-Feng; He, Guo-Qiang; Cao, Xin-Wei; Lu, Yi-Xin
2016-01-01
The impact parameter dependence of \\rpi ratio is examined in heavy-ion collisions at 400MeV/nucleon within a transport model. It is shown that the sensitivity of \\rpi ratio on symmetry energy shows a transition from central to peripheral collisions, i.e., the stiffer symmetry energy leads to a larger \\rpi ratio in peripheral collisions while the softer symmetry energy always leads this ratio to be larger in central collisions. After checking the kinematic energy distribution of \\rpi ratio, we...
SYMMETRY PROPERTIES OF THE COULOMB POTENTIAL WITH A LINEAR DEPENDENCE ON ENERGY
Directory of Open Access Journals (Sweden)
Radu Budaca
2017-12-01
Full Text Available The D-dimensional Schr ̈odinger equation for a Coulomb potential with a coupling constant depending linearly on energy is analytically solved. The energy spectrum in the asymptotic regime of the slope parameter is found to be fully determined up to a scale only by its quantum numbers. The raising and lowering operators for this limiting model are determined from the recurrence properties of the associated solutions. It is shown that they satisfy the commutation relations of an SU(1,1 algebra and act on wave-functions which are normalized differently from the case of the usual bound state problem for an energy independent Coulomb potential.
Partial and quasi dynamical symmetries in quantum many-body systems
International Nuclear Information System (INIS)
Leviatan, A
2015-01-01
We introduce the notions of partial dynamical symmetry (PDS) and quasi dynamical symmetry (QDS) and demonstrate their relevance to nuclear spectroscopy, to quantum phase transitions and to mixed systems with regularity and chaos. The analysis serves to highlight the potential role of PDS and QDS towards understanding the emergent “simplicity out of complexity” exhibited by complex many-body systems. (paper)
Nuclear power prospects and potential: scenarios
International Nuclear Information System (INIS)
Rogner, Hans-Hogler; McDonald, Alan; )
2002-01-01
This paper outlines a range of scenarios describing what the world's energy system might look in the middle of the century, and what nuclear energy's most profitable role might be. The starting point is the 40 non-greenhouse-gas-mitigation scenarios in the Special Report on Emission Scenarios (SRES) of the Intergovernmental Panel on Climate Change (IPCC). Given their international authorship and comprehensive review by governments and scientific experts, the SRES scenarios are the state of the art in long-term energy scenarios
International Nuclear Information System (INIS)
Shunkeev, K.; Sagimbaeva, Sh.; Shunkeev, S.
2007-01-01
Effect of auto-localized excitons (ALE) luminescence strengthening is conditioned by two mechanisms: either decrease of potential barrier divided of quasi-free states and auto-localized states or decrease of emission-less channel effectiveness of exciton decay on primary radiation defects. In considered range (80 K) all excitons are only in auto-localized state. Therefore a realization of the first mechanism is improbable, For instant, in KI crystal at 80-100 K luminescence of free exciton is completely putting out, and ALE luminescence has maximal intensity. It is known that in the temperature range when ALE luminescence putting out is beginning an effectiveness of radiation defects is beginning to grow. This effect is related with predominating at that time emission-less exciton decay on radiation defects (F-H pairs). Experimentally by luminescence spectroscopy method activation energy of temperature putting out of ALE in AHC under uniaxial deformation. It is revealed, that increase of activation energy value has observed in a number of crystals: KBr→NaCl→KI→Na Br→CsBr→RbI. It is concluded, that effect of ALE intensity building-up and decrease of effectiveness of radiation defect formation are interpreted by growth of potential barrier of ALE decay into radiation defects under low symmetry of AHC lattice of low-temperature uniaxial deformation
Additional potential effects of nuclear war on ecological systems
International Nuclear Information System (INIS)
Hutchinson, T.C.; Harwell, M.A.; Cropper, W.P. Jr.; Grover, H.D.
1985-01-01
The authors summarize biological and ecosystem responses to enhanced UV-B, air pollutants, radiation, and fire. The concentrations and biological responses associated with these perturbations are based on current experience and experimentation. Additional research is needed to quantify probable post-nuclear war exposures and potential responses. A summary is provided of all the potential effects of nuclear war on the variety of the Earth's ecosystems, including perturbations from climatic alterations, radiation, pollutants, and UV-B
Dynamical symmetries for fermions
International Nuclear Information System (INIS)
Guidry, M.
1989-01-01
An introduction is given to the Fermion Dynamical Symmetry Model (FDSM). The analytical symmetry limits of the model are then applied to the calculation of physical quantities such as ground-state masses and B(E 2 ) values in heavy nuclei. These comparisons with data provide strong support for a new principle of collective motion, the Dynamical Pauli Effect, and suggest that dynamical symmetries which properly account for the pauli principle are much more persistent in nuclear structure than the corresponding boson symmetries. Finally, we present an assessment of criticisms which have been voiced concerning the FDSM, and a discussion of new phenomena and ''exotic spectroscopy'' which may be suggested by the model. 14 refs., 8 figs., 4 tabs
Configuration and technology implications of potential nuclear hydrogen system applications.
Energy Technology Data Exchange (ETDEWEB)
Conzelmann, G.; Petri, M.; Forsberg, C.; Yildiz, B.; ORNL
2005-11-05
Nuclear technologies have important distinctions and potential advantages for large-scale generation of hydrogen for U.S. energy services. Nuclear hydrogen requires no imported fossil fuels, results in lower greenhouse-gas emissions and other pollutants, lends itself to large-scale production, and is sustainable. The technical uncertainties in nuclear hydrogen processes and the reactor technologies needed to enable these processes, as well waste, proliferation, and economic issues must be successfully addressed before nuclear energy can be a major contributor to the nation's energy future. In order to address technical issues in the time frame needed to provide optimized hydrogen production choices, the Nuclear Hydrogen Initiative (NHI) must examine a wide range of new technologies, make the best use of research funding, and make early decisions on which technology options to pursue. For these reasons, it is important that system integration studies be performed to help guide the decisions made in the NHI. In framing the scope of system integration analyses, there is a hierarchy of questions that should be addressed: What hydrogen markets will exist and what are their characteristics? Which markets are most consistent with nuclear hydrogen? What nuclear power and production process configurations are optimal? What requirements are placed on the nuclear hydrogen system? The intent of the NHI system studies is to gain a better understanding of nuclear power's potential role in a hydrogen economy and what hydrogen production technologies show the most promise. This work couples with system studies sponsored by DOE-EE and other agencies that provide a basis for evaluating and selecting future hydrogen production technologies. This assessment includes identifying commercial hydrogen applications and their requirements, comparing the characteristics of nuclear hydrogen systems to those market requirements, evaluating nuclear hydrogen configuration options
Exact dynamical and partial symmetries
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A, E-mail: ami@phys.huji.ac.il [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)
2011-03-01
We discuss a hierarchy of broken symmetries with special emphasis on partial dynamical symmetries (PDS). The latter correspond to a situation in which a non-invariant Hamiltonian accommodates a subset of solvable eigenstates with good symmetry, while other eigenstates are mixed. We present an algorithm for constructing Hamiltonians with this property and demonstrate the relevance of the PDS notion to nuclear spectroscopy, to quantum phase transitions and to mixed systems with coexisting regularity and chaos.
Exact dynamical and partial symmetries
International Nuclear Information System (INIS)
Leviatan, A
2011-01-01
We discuss a hierarchy of broken symmetries with special emphasis on partial dynamical symmetries (PDS). The latter correspond to a situation in which a non-invariant Hamiltonian accommodates a subset of solvable eigenstates with good symmetry, while other eigenstates are mixed. We present an algorithm for constructing Hamiltonians with this property and demonstrate the relevance of the PDS notion to nuclear spectroscopy, to quantum phase transitions and to mixed systems with coexisting regularity and chaos.
Directory of Open Access Journals (Sweden)
Piotr Matczak
2017-01-01
Full Text Available The present work starts with providing a description of the halogen bonding (XB interaction between the halogen atom of MH3X (where M = C–Pb and X = I, At and the N atom of HCN. This interaction leads to the formation of stable yet very weakly bound MH3X⋯NCH complexes for which the interaction energy (Eint between MH3X and HCN is calculated using various symmetry-adapted perturbation theory (SAPT methods combined with the def2-QZVPP basis set and midbond functions. This basis set assigns effective core potentials (ECPs not only to the I or At atom directly participating in the XB interaction with HCN but also to the M atom when substituted with Sn or Pb. Twelve SAPT methods (or levels are taken into consideration. According to the SAPT analysis of Eint, the XB interaction in the complexes shows mixed electrostatic-dispersion nature. Next, the accuracy of SAPT Eint is evaluated by comparing with CCSD(T reference data. This comparison reveals that high-order SAPT2+(3 method and the much less computationally demanding SAPT(DFT method perform very well in describing Eint of the complexes. However, the accuracy of these methods decreases dramatically if they are combined with the so-called Hartree-Fock correction.
Potential strategic consequences of the nuclear energy revival
International Nuclear Information System (INIS)
Ferguson, Ch.D.
2010-01-01
Many people have projected their hopes and fears onto nuclear power. Nuclear energy has both benefits and risks, and disagreement persists about whether this energy source is, on balance, more of an asset than a liability. This debate involves a complicated set of factors that are difficult to assess, let alone fully resolve because of the differing interests in various countries' use and pursuit of nuclear power. Renewed interest throughout the globe in harnessing this energy source has stoked this perennial debate and raised concern about security threats from states and non-state actors while holding out the promise of more electricity for more people. While the motivations for nuclear energy vary among states, the two primary public goods this energy source offers are countering human-induced climate change and providing for greater energy security. Although views on how to achieve energy security differ, the essential aspect for nuclear energy is that for several countries, especially those with scarce indigenous energy sources from fossil fuels, investing in nuclear power plants diversifies electricity production portfolios and helps reduce dependence on foreign sources of energy. The focus here is on assessing the potential security consequences of increased use of nuclear power in the existing nuclear power states and most importantly in many more states that have in recent years expressed interest in this power source. The risks of nuclear power include possible reactor accidents, release of radioactive waste to the environment, attacks on or sabotage of nuclear facilities, and misuse of peaceful nuclear technologies to make nuclear weapons. While safety of nuclear plants and disposal of radioactive waste are important issues, this paper analyzes the latter two issues. In addition, it addresses two under-examined risks: military attacks on nuclear facilities and the effects on security alliances and conventional arms buildups as more countries seek to
Introduction to Chiral Symmetry
Energy Technology Data Exchange (ETDEWEB)
Koch, Volker [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2017-05-09
These lectures are an attempt to a pedagogical introduction into the elementary concepts of chiral symmetry in nuclear physics. We will also discuss some effective chiral models such as the linear and nonlinear sigma model as well as the essential ideas of chiral perturbation theory. We will present some applications to the physics of ultrarelativistic heavy ion collisionsd.
Energy Technology Data Exchange (ETDEWEB)
Walker-Loud, Andre [College of William and Mary, Williamsburg, VA (United States)
2016-10-14
The research supported by this grant is aimed at probing the limits of the Standard Model through precision low-energy nuclear physics. The work of the PI (AWL) and additional personnel is to provide theory input needed for a number of potentially high-impact experiments, notably, hadronic parity violation, Dark Matter direct detection and searches for permanent electric dipole moments (EDMs) in nucleons and nuclei. In all these examples, a quantitative understanding of low-energy nuclear physics from the fundamental theory of strong interactions, Quantum Chromo-Dynamics (QCD), is necessary to interpret the experimental results. The main theoretical tools used and developed in this work are the numerical solution to QCD known as lattice QCD (LQCD) and Effective Field Theory (EFT). This grant is supporting a new research program for the PI, and as such, needed to be developed from the ground up. Therefore, the first fiscal year of this grant, 08/01/2014-07/31/2015, has been spent predominantly establishing this new research effort. Very good progress has been made, although, at this time, there are not many publications to show for the effort. After one year, the PI accepted a job at Lawrence Berkeley National Laboratory, so this final report covers just a single year of five years of the grant.
Mathematical modeling of potentially hazardous nuclear objects with time shifts
International Nuclear Information System (INIS)
Gharakhanlou, J.; Kazachkov, I.V.
2012-01-01
The aggregate models for potentially hazardous objects with time shifts are used for mathematical modeling and computer simulation. The effects of time delays are time forecasts are analyzed. The influence of shift arguments on the nonlinear differential equations is discussed. Computer simulation has established the behavior of potentially hazardous nuclear object
Potential for sharing nuclear power infrastructure between countries
International Nuclear Information System (INIS)
2006-10-01
The introduction or expansion of a nuclear power programme in a country and its successful execution is largely dependent on the network of national infrastructure, covering a wide range of activities and capabilities. The infrastructure areas include legal framework, safety and environmental regulatory bodies, international agreements, physical facilities, finance, education, training, human resources and public information and acceptance. The wide extent of infrastructure needs require an investment that can be too large or onerous for the national economy. The burden of infrastructure can be reduced significantly if a country forms a sharing partnership with other countries. The sharing can be at regional or at multinational level. It can include physical facilities, common programmes and knowledge, which will reflect in economic benefits. The sharing can also contribute in a significant manner to harmonization of codes and standards in general and regulatory framework in particular. The opportunities and potential of sharing nuclear power infrastructure is determined by the objectives, strategy and scenario of the national nuclear power programme. A review of individual infrastructure items shows that there are several opportunities for sharing of nuclear power infrastructure between countries if they cooperate with each other. International cooperation and sharing of nuclear power infrastructure are not new. This publication provides criteria and guidance for analyzing and identifying the potential for sharing of nuclear power infrastructure during the stages of nuclear power project life cycle. The target users are decision makers, advisers and senior managers in utilities, industrial organizations, regulatory bodies and governmental organizations in countries adopting or extending nuclear power programmes. This publication was produced within the IAEA programme directed to increase the capability of Member States to plan and implement nuclear power
Energy Perspectives In Switzerland: The Potential Of Nuclear Power
International Nuclear Information System (INIS)
Foskolos, K.; Hardegger, P.
2005-01-01
In 2004, discussions were started in Switzerland concerning future of energy supply, including domestic electricity generation. On behalf of the Federal Office of Energy, PSI undertook a study to evaluate the potential of future nuclear technologies, covering electricity demand, with a time horizon up to 2050. It has been shown that nuclear power plants (NPPs) of the Third Generation, similar to the ones currently under construction in several other countries, built on the existing nuclear sites in Switzerland, have the potential to replace, at competitive costs, the existing nuclear plants, and even to cover (postulated) increases in electricity demand. Because of their late maturity (expected at the earliest around 2030), NPPs of the Fourth Generation, which are currently under development, cannot play a major role in Switzerland, since, with the exception of the Leibstadt NPP, all decisions regarding replacement of the current Swiss NPPs have to be taken before 2030. (author)
Aniello, Paolo; Chruściński, Dariusz
2017-07-01
A symmetry witness is a suitable subset of the space of selfadjoint trace class operators that allows one to determine whether a linear map is a symmetry transformation, in the sense of Wigner. More precisely, such a set is invariant with respect to an injective densely defined linear operator in the Banach space of selfadjoint trace class operators (if and) only if this operator is a symmetry transformation. According to a linear version of Wigner’s theorem, the set of pure states—the rank-one projections—is a symmetry witness. We show that an analogous result holds for the set of projections with a fixed rank (with some mild constraint on this rank, in the finite-dimensional case). It turns out that this result provides a complete classification of the sets of projections with a fixed rank that are symmetry witnesses. These particular symmetry witnesses are projectable; i.e. reasoning in terms of quantum states, the sets of ‘uniform’ density operators of corresponding fixed rank are symmetry witnesses too.
Saadaoui, H.; Morris, G. D.; Salman, Z.; Song, Q.; Chow, K. H.; Hossain, M. D.; Levy, C. D. P.; Parolin, T. J.; Pearson, M. R.; Smadella, M.; Wang, D.; Greene, L. H.; Hentges, P. J.; Kiefl, R. F.; Macfarlane, W. A.
2011-02-01
Weak spontaneous magnetic fields are observed near the surface of YBa2Cu3O7-δ films using β-detected nuclear magnetic resonance. Below Tc, the magnetic field distribution in a silver film evaporated onto the superconductor shows additional line broadening, indicating the appearance of small disordered magnetic fields. The line broadening increases linearly with a weak external magnetic field applied parallel to the surface, and is depth independent up to 45 nm from the Ag/YBa2Cu3O7-δ interface. The magnitude of the line broadening extrapolated to zero applied field is less than 0.2 G, and is close to nuclear dipolar broadening in the Ag. This indicates that any fields due to broken time-reversal symmetry are less than 0.2 G.
Microscopic nuclear structure calculations with modern meson-exchange potentials
International Nuclear Information System (INIS)
Hjort-Jensen, M.; Osnes, E.; Muether, H.; Schmid, K.W.; Kuo, T.T.S.
1990-07-01
The report presents the results of microscopic nuclear shell-model calculations using three different nucleon-nucleon potentials. These are the phenomenological Reid-Soft-Core potential and the meson-exchange potentials of the Paris and the Bonn groups. It is found that the Bonn potential yields sd-shell matrix elements which are more attractive than those obtained with the Reid or the Paris potentials. The harmonic-oscillator matrix elements of the Bonn potential are also in better agreement with the empirically derived matrix elements of Wildenthal. The implications are discussed. 27 refs., 4 figs., 1 tab
Increased nuclear thioredoxin-1 potentiates cadmium-induced cytotoxicity.
Go, Young-Mi; Orr, Michael; Jones, Dean P
2013-01-01
Cadmium (Cd) is a widely dispersed environmental agent that causes oxidative toxicity through mechanisms that are sensitive to thioredoxin-1 (Trx1). Trx1 is a cytoplasmic protein that translocates to nuclei during oxidative stress. Recent research shows that interaction of Trx1 with actin plays a critical role in cell survival and that increased nuclear Trx-1 potentiates proinflammatory signaling and death in cell and mouse models. These observations indicate that oxidative toxicity caused by low-dose Cd could involve disruption of actin-Trx1 interaction, nuclear Trx1 translocation, and potentiation of proinflammatory cell death mechanisms. In this study, we investigated the role of nuclei-localized Trx1 in Cd-induced inflammation and cytotoxicity using in vitro and in vivo models. The results show that Cd stimulated nuclear translocation of Trx1 and p65 of NF-κB. Elevation of Trx1 in nuclei in in vitro cells and kidney of transgenic mice potentiated Cd-stimulated NF-κB activation and cell death. Cd-stimulated Trx1 nuclear translocation and NF-κB activation were inhibited by cytochalasin D, an inhibitor of actin polymerization, suggesting that actin regulates Trx1 nuclear translocation and NF-κB activation by Cd. A nuclear-targeted dominant negative form of Trx1 blocked Cd-stimulated NF-κB activation and decreased cell death. Addition of zinc, known to antagonize Cd toxicity by increasing metallothionein, had no effect on Cd-stimulated nuclear translocation of Trx1 and NF-κB activation. Taken together, the results show that nuclear translocation and accumulation of redox-active Trx1 in nuclei play an important role in Cd-induced inflammation and cell death.
Expansion potential for existing nuclear power station sites
International Nuclear Information System (INIS)
Cope, D.F.; Bauman, H.F.
1977-01-01
This report is a preliminary analysis of the expansion potential of the existing nuclear power sites, in particular their potential for development into nuclear energy centers (NECs) of 10 (GW(e) or greater. The analysis is based primarily on matching the most important physical characteristics of a site against the dominating site criteria. Sites reviewed consist mainly of those in the 1974 through 1976 ERDA Nuclear Power Stations listings without regard to the present status of reactor construction plans. Also a small number of potential NEC sites that are not associated with existing power stations were reviewed. Each site was categorized in terms of its potential as: a dispersed site of 5 GW(e) or less; a mini-NEC of 5 to 10 GW(e); NECs of 10 to 20 GW(e); and large NECs of more than 20 GW(e). The sites were categorized on their ultimate potential without regard to political considerations that might restrain their development. The analysis indicates that nearly 40 percent of existing sites have potential for expansion to nuclear energy centers
Boson-exchange nucleon-nucleon potential and nuclear structure
International Nuclear Information System (INIS)
Grange, Pierre.
1976-01-01
A fully momentum-dependent one-boson-exchange potential is derived which takes into account the mesons, π, eta, sigma, rho, ω and phi. Scattering bound states and nuclear matter properties are studied in momentum space. The use of such potential is shown to be as easy as the use of more simple phenomenological interactions. In nuclear matter the formalism of Bethe-Goldstone is chosen to compute the binding energy versus density in the approximation of two-body and three-body correlations. The three-body correlated wave function obtained is then used [fr
The Nuclear Potential in Heavy-Ion Fusion
Dasgupta, M.; Hinde, D.; Newton, J. O.; Hagino, K.
Fits to high precision fusion cross-sections even for ZPZT Woods-Saxon potential of ≃1~fm, which is much larger than the commonly accepted value of ≃~0.65 fm. However, use of large values of a necessarily makes the potential pocket very shallow for realistic values of the nuclear potential depth. For larger values of angular momenta the pocket disappears, and a fusion barrier energy or radius can no longer be defined. In the absence of a potential pocket, fusion does not occur in the commonly used realistic coupled channels code CCFULL where fusion is calculated by applying an incoming wave boundary condition at the position of the minimum of the attractive pocket. For this reason, realistic coupled channels calculations with large values of a have needed unrealistically deep nuclear potentials. Once the potential depth is constrained to reasonable values, the data cannot be explained by simply changing the diffuseness of the nuclear potential. This indicates the necessity to go beyond the potential model, and incorporate dynamical effects as the two nuclei move towards fusion, even for light systems with ZPZT < 1000.
Partial Dynamical Symmetry in Deformed Nuclei
International Nuclear Information System (INIS)
Leviatan, A.
1996-01-01
We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. copyright 1996 The American Physical Society
Simultaneous occurrence of distinct symmetries in nuclei
International Nuclear Information System (INIS)
Leviatan, A.
2016-01-01
We show that distinct emergent symmetries, such as partial dynamical symmetry and quasi dynamical symmetry, can occur simultaneously in the same or different eigenstates of the Hamiltonian. Implications for nuclear spectroscopy in the rare-earth region and for first-order quantum phase transitions between spherical and deformed shapes, are considered. (paper)
Partial Dynamical Symmetry in Deformed Nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)
1996-07-01
We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. {copyright} {ital 1996 The American Physical Society.}
TMI-2 remote cameras, teleoperators, and other potential nuclear applications
International Nuclear Information System (INIS)
Pavelek, M.D. II
1987-01-01
Evaluation, testing, and use of fixed-position, remotely operated video-camera equipment and various teleoperators at Three Mile Island Nuclear Station Unit 2 (TMI-2) have demonstrated that significant potential advantages may be obtained by installing remotely operated equipment at other nuclear facilities. Teleoperators at TMI-2 have permitted successful operations in areas not accessible to personnel. Insights gained from the remotely operated camera systems and teleoperators used and evaluated at TMI-2 are discussed from the perspective of actual applications and the potential benefits from deployment of remote devices at other nuclear facilities. Actual exposure savings achieved are not presented because these applications and resultant exposure savings are specific to TMI-2. 3 refs., 4 figs
Khater, A. H.; Callebaut, D. K.; Abdelhameed, T. N.
2006-03-01
Lie groups involving potential symmetries are applied in connection with the system of magnetohydrodynamic equations for incompressible matter with Ohm's law for finite resistivity and Hall current in cylindrical geometry. Some simplifications allow to obtain a Fokker-Planck type equation. Invariant solutions are obtained involving the effects of time-dependent flow and the Hall-current. Some interesting side results of this approach are new exact solutions that do not seem to have been reported in the literature.
Methodology for characterizing potential adversaries of Nuclear Material Safeguards Systems
Energy Technology Data Exchange (ETDEWEB)
Kirkwood, C.W.; Pollock, S.M.
1978-11-01
The results are described of a study by Woodward--Clyde Consultants to assist the University of California Lawrence Livermore Laboratory in the development of methods to analyze and evaluate Nuclear Material Safeguards (NMS) Systems. The study concentrated on developing a methodology to assist experts in describing, in quantitative form, their judgments about the characteristics of potential adversaries of NMS Systems.
Heavy particle decay studies using different versions of nuclear potentials
Santhosh, K. P.; Sukumaran, Indu
2017-10-01
The heavy particle decay from 212-240Pa , 219-245Np , 228-246Pu , 230-249Am , and 232-252Cm leading to doubly magic 208Pb and its neighboring nuclei have been studied using fourteen versions of nuclear potentials. The study has shown that the barrier penetrability as well as the decay half-lives are found to vary with the nuclear potential used. The investigated decay events of the emission of the clusters 22Ne , 24Ne , 26Mg , 28Mg , 32Si and 33Si are not experimentally detected yet but may be detectable in the future. As most of the half-lives predicted are found to lie within the experimental upper limit, T 1/2 parents with varying slopes and intercepts. Also, it is to be noted that the linearity of the GN plots is unaltered using different nuclear potentials. The universal curve studied ( log10 T 1/2 vs. -ln P for various clusters emitted from various parents shows a linear behavior with the same slope and intercept irrespective of the nuclear potential used.
Methodology for characterizing potential adversaries of Nuclear Material Safeguards Systems
International Nuclear Information System (INIS)
Kirkwood, C.W.; Pollock, S.M.
1978-11-01
The results are described of a study by Woodward--Clyde Consultants to assist the University of California Lawrence Livermore Laboratory in the development of methods to analyze and evaluate Nuclear Material Safeguards (NMS) Systems. The study concentrated on developing a methodology to assist experts in describing, in quantitative form, their judgments about the characteristics of potential adversaries of NMS Systems
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
Potential Benefits to the Philippines of a Nuclear Facility
International Nuclear Information System (INIS)
Asuncion-Astronomo, A.; Romallosa, K.M.D.; Olivares, R.U.
2015-01-01
During the late 1950’s, the Philippines was one of the many countries which began the pursuit of the beneficial applications of atomic energy. With the commissioning of the first Philippine Research Reactor (PRR-1) which attained its first criticality in 1963, our country had the capability for radioisotope production, activation analysis of materials, irradiation studies and various opportunities for basic and applied nuclear science research. The Nuclear Power Plant (PNNP-1) in training plant operators and regulators for the first Philippine Nuclear Power Plant (PNPP-1) in Bataan, which was eventually mothballed in 1986. It is thus unfortunate that the only operating nuclear facility in the country, the PRR-1 encountered technical problems during an upgrade and was shut down in 1988. The problem was not resolved and eventually led to the decommissioning of the PRR-1 in 2005. Without an operating nuclear facility available in the country, the number of personnel knowledgeable and skilled in reactor and nuclear science and engineering has greatly declined and lagged behind our counterparts. This has been the situation for more than two decaded and can only be addressed if the country decides to put up a new nuclear facility. It is acknowledged that putting up a nuclear facility is a major undertaking which requires careful planning, preparation and investment. Thus, a decision by any country to embark on this poster, we will provide an overview of the many potential benefits as well as challenges of establishing a new research reactor and/or accelerator facility in the country. The global distribution, comparisons, capabilities and the different application of these facilities will presented as well.(author)
K- nuclear potentials from in-medium chirally motivated models
International Nuclear Information System (INIS)
Cieply, A.; Gazda, D.; Mares, J.; Friedman, E.; Gal, A.
2011-01-01
A self-consistent scheme for constructing K - nuclear optical potentials from subthreshold in-medium KN s-wave scattering amplitudes is presented and applied to analysis of kaonic atoms data and to calculations of K - quasibound nuclear states. The amplitudes are taken from a chirally motivated meson-baryon coupled-channel model, both at the Tomozawa-Weinberg leading order and at the next to leading order. Typical kaonic atoms potentials are characterized by a real part -Re V K - chiral =85±5 MeV at nuclear matter density, in contrast to half this depth obtained in some derivations based on in-medium KN threshold amplitudes. The moderate agreement with data is much improved by adding complex ρ- and ρ 2 -dependent phenomenological terms, found to be dominated by ρ 2 contributions that could represent KNN→YN absorption and dispersion, outside the scope of meson-baryon chiral models. Depths of the real potentials are then near 180 MeV. The effects of p-wave interactions are studied and found secondary to those of the dominant s-wave contributions. The in-medium dynamics of the coupled-channel model is discussed and systematic studies of K - quasibound nuclear states are presented.
International Nuclear Information System (INIS)
Blum, Alexander Simon
2009-01-01
This thesis deals with the possibility of describing the flavor sector of the Standard Model of Particle Physics (with neutrino masses), that is the fermion masses and mixing matrices, with a discrete, non-abelian flavor symmetry. In particular, mass independent textures are considered, where one or several of the mixing angles are determined by group theory alone and are independent of the fermion masses. To this end a systematic analysis of a large class of discrete symmetries, the dihedral groups, is analyzed. Mass independent textures originating from such symmetries are described and it is shown that such structures arise naturally from the minimization of scalar potentials, where the scalars are gauge singlet flavons transforming non-trivially only under the flavor group. Two models are constructed from this input, one describing leptons, based on the group D 4 , the other describing quarks and employing the symmetry D 14 . In the latter model it is the quark mixing matrix element V ud - basically the Cabibbo angle - which is at leading order predicted from group theory. Finally, discrete flavor groups are discussed as subgroups of a continuous gauge symmetry and it is shown that this implies that the original gauge symmetry is broken by fairly large representations. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Blum, Alexander Simon
2009-06-10
This thesis deals with the possibility of describing the flavor sector of the Standard Model of Particle Physics (with neutrino masses), that is the fermion masses and mixing matrices, with a discrete, non-abelian flavor symmetry. In particular, mass independent textures are considered, where one or several of the mixing angles are determined by group theory alone and are independent of the fermion masses. To this end a systematic analysis of a large class of discrete symmetries, the dihedral groups, is analyzed. Mass independent textures originating from such symmetries are described and it is shown that such structures arise naturally from the minimization of scalar potentials, where the scalars are gauge singlet flavons transforming non-trivially only under the flavor group. Two models are constructed from this input, one describing leptons, based on the group D{sub 4}, the other describing quarks and employing the symmetry D{sub 14}. In the latter model it is the quark mixing matrix element V{sub ud} - basically the Cabibbo angle - which is at leading order predicted from group theory. Finally, discrete flavor groups are discussed as subgroups of a continuous gauge symmetry and it is shown that this implies that the original gauge symmetry is broken by fairly large representations. (orig.)
Interdependence of different symmetry energy elements
Mondal, C.; Agrawal, B. K.; De, J. N.; Samaddar, S. K.; Centelles, M.; Viñas, X.
2017-08-01
Relations between the nuclear symmetry energy coefficient and its density derivatives are derived. The relations hold for a class of interactions with quadratic momentum dependence and a power-law density dependence. The structural connection between the different symmetry energy elements as obtained seems to be followed by almost all reasonable nuclear energy density functionals, both relativistic and nonrelativistic, suggesting a universality in the correlation structure. This, coupled with known values of some well-accepted constants related to nuclear matter, helps in constraining values of different density derivatives of the nuclear symmetry energy, shedding light on the isovector part of the nuclear interaction.
Nuclear energy role and potential for global sustainable development
International Nuclear Information System (INIS)
Ujita, H.; Matsui, K.
2006-01-01
The long-term energy supply simulation that optimizes the energy system cost until 2100 for the world is being performed, by using the energy module of GRAPE model, where energy demand under the C02 emission constraint etc. is assumed. The model has been taken up for the trial calculation in I PCC the third report . Role and potential of nuclear energy system in the energy options is discussed here from the viewpoint of sustainable development with protecting from global warming. Taking the effort for energy conservation as major premise, carbon-sequestration for fossil fuel, renewable energy and nuclear energy should be altogether developed under the C02 constraint. Especially, fast breeder reactor will be attached importance to, as the 22nd century is approaching, due to its carbon free and resource limitless features when the nuclear generation cost is cheap as a current light water reactor level. It takes time around 30 years in order for breeding of Pu, a fast breeder reactor will begin to be introduced from around 2030. If the period for the technology establish of nuclear fuel cycle is assumed to be 30 years, it is necessary to start technical development right now. If the Kyoto Protocol, the emission constraint on only the developed countries, is extended in 21st century, it will promote the growth of nuclear power in the developed countries in the first half of the century. After 2050, the developing countries will face the shortage of uranium and plutonium. Carbon emission constraint should be covered all countries in the World not only for the developed countries but also for the developing countries. Therefore, it is important that the developing countries will use nuclear power effectively from the viewpoint of harmonization of energy growth and global environment. The policy that nuclear power is considered as Clean Development Mechanism would mitigate such global warming problems
Evaluation of a potential nuclear fuel repository criticality: Lessons learned
Energy Technology Data Exchange (ETDEWEB)
Wilson, J.R.; Evans, D.
1995-10-01
This paper presents lessons learned from a Probabilistic Risk Assessment (PRA) of the potential for a criticality in a repository containing spent nuclear fuel with high enriched uranium. The insights gained consisted of remarkably detailed conclusions about design issues, failure mechanisms, frequencies and source terms for events up to 10,000 years in the future. Also discussed are the approaches taken by the analysts in presenting this very technical report to a nontechnical and possibly antagonistic audience.
Intermediate-energy nuclear photoabsorption and the pion optical potential
International Nuclear Information System (INIS)
Christillin, P.
1984-01-01
Nuclear photoabsorption around the pion threshold is schematised as photoproduction of a pion which undergoes final-stae interaction with the nucleus, accounted for by the pion optical potential. It is shown that real pion photoproduction and exchange effects are naturally described by the same mechanism with a non-static pion. The complementarity of photoabsorption to pion physics and its usefulness in gaining new information about pion-nucleus dynamics are stressed. (author)
Evaluation of a potential nuclear fuel repository criticality: Lessons learned
International Nuclear Information System (INIS)
Wilson, J.R.; Evans, D.
1995-01-01
This paper presents lessons learned from a Probabilistic Risk Assessment (PRA) of the potential for a criticality in a repository containing spent nuclear fuel with high enriched uranium. The insights gained consisted of remarkably detailed conclusions about design issues, failure mechanisms, frequencies and source terms for events up to 10,000 years in the future. Also discussed are the approaches taken by the analysts in presenting this very technical report to a nontechnical and possibly antagonistic audience
Additional factors of nuclear war potential effect on ecosystems
International Nuclear Information System (INIS)
Khatchinson, T.; Kharuehll, M.; Kropper, U.; Grover, G.
1988-01-01
Available information on response of organisms and ecosystems to increase of ultraviolet radiation, air borne pollutant concentrations, radiation and fires in case of nuclear war is generalized. The presented data are based on accumulated experience and experimental investigations. Potentiality of arising a great amount of stress effect localized regions is noted. Severe consequences for agriculture and population, particularly in sinergic stress effect, are not excluded. 169 refs.; 5 figs.; 25 tabs
Potential applications of nanostructured materials in nuclear waste management.
Energy Technology Data Exchange (ETDEWEB)
Braterman, Paul S. (The University of North Texas, Denton, TX); Phol, Phillip Isabio; Xu, Zhi-Ping (The University of North Texas, Denton, TX); Brinker, C. Jeffrey; Yang, Yi (University of New Mexico, Albuquerque, NM); Bryan, Charles R.; Yu, Kui; Xu, Huifang (University of New Mexico, Albuquerque, NM); Wang, Yifeng; Gao, Huizhen
2003-09-01
This report summarizes the results obtained from a Laboratory Directed Research & Development (LDRD) project entitled 'Investigation of Potential Applications of Self-Assembled Nanostructured Materials in Nuclear Waste Management'. The objectives of this project are to (1) provide a mechanistic understanding of the control of nanometer-scale structures on the ion sorption capability of materials and (2) develop appropriate engineering approaches to improving material properties based on such an understanding.
Isospin symmetry breaking in sd shell nuclei
International Nuclear Information System (INIS)
Lam, Y.W.
2011-12-01
In the thesis, we develop a microscopic approach to describe the isospin-symmetry breaking effects in sd-shell nuclei. The work is performed within the nuclear shell model. A realistic isospin-conserving Hamiltonian is perfected by a charge-dependent part consisting of the Coulomb interaction and Yukawa-type meson exchange potentials to model charge-dependent forces of nuclear origin. The extended database of the experimental isobaric mass multiplet equation coefficients was compiled during the thesis work and has been used in a fit of the Hamiltonian parameters. The constructed Hamiltonian provides an accurate theoretical description of the isospin mixing nuclear states. A specific behaviour of the IMME (Isobaric Multiplet Mass Equation) coefficients have been revealed. We present two important applications: (i) calculations of isospin-forbidden proton emission amplitudes, which is often of interest for nuclear astrophysics, and (ii) calculation on corrections to nuclear Fermi beta decay, which is crucial for the tests of fundamental symmetries of the weak interaction. (author)
Transmutation potential of current and innovative nuclear power systems
International Nuclear Information System (INIS)
Slessarev, I.; Salvatores, M.; Uematsu, M.
1993-01-01
In the present paper we have investigated the transmutation potential of different nuclear systems from a physical point of view. Transuranium (TRU) elements have been considered, but also long lived fission products (LLFP). The potential for transmutation has to take into account not only the consumption of a specific nucleus (or of a specific 'family' of nuclei), but also the reproduction of other nuclei of higher masses. The present study allows an intercomparison taking into account both aspects. Technological, safety and design constraints were not considered at this stage. However strategic indications for future studies have been obtained. 3 refs., 3 tabs
Nuclear industry powering up to tackle potential threats from cyberspace
Energy Technology Data Exchange (ETDEWEB)
Shepherd, John [nuclear 24, Brighton (United Kingdom)
2015-06-15
In June 2015, the International Atomic Energy Agency (IAEA), in cooperation with international agencies including the crime-fighting organisation Interpol, will host a major conference on the protection of computer systems and networks that support operations at the world's nuclear facilities. According to the IAEA, the use of computers and other digital electronic equipment in physical protection systems at nuclear facilities, as well as in facility safety systems, instrumentation, information processing and communication, ''continues to grow and presents an ever more likely target for cyber-attack''. The international nuclear industry is right to take heed of ever-evolving security threats, deal with them accordingly, and be as open and transparent as security allows about what is being done, which will reassure the general public. However, the potential menace of cyberspace should not be allowed to become such a distraction that it gives those who are ideologically opposed to nuclear another stick with which to beat the industry.
Market potential for non-electric applications of nuclear energy
International Nuclear Information System (INIS)
2002-01-01
The objective of this report is to assess the market potential for the non-electric applications of nuclear energy in the near (before 2020) and long (2020-2050) terms. The main non-electric applications are defined here as district heating, desalination (of sea, brackish and waste water), industrial heat supply, ship propulsion and the energy supply for spacecraft. This report is principally devoted to these applications, although a less detailed assessment of some innovative applications (e.g. hydrogen production and coal gasification) is also provided. While the technical details of these applications are covered briefly, emphasis is placed on the economic and other factors that may promote or hinder the penetration of the nuclear option into the market for non-electric energy services. The report is intentionally targeted towards expected demands. It is for this reason that its sections are structured by demand categories and not according to possible reactor types. At the same time, the orientation on the demand side can result in overlaps at the supply side, because the same nuclear reactor can often serve more than one type of demand. Such cases are noted as appropriate. Each section characterizes a specific non-electric application in terms of its market size, its prospects for nuclear technologies and the economic competitiveness of the technologies
Nuclear industry powering up to tackle potential threats from cyberspace
International Nuclear Information System (INIS)
Shepherd, John
2015-01-01
In June 2015, the International Atomic Energy Agency (IAEA), in cooperation with international agencies including the crime-fighting organisation Interpol, will host a major conference on the protection of computer systems and networks that support operations at the world's nuclear facilities. According to the IAEA, the use of computers and other digital electronic equipment in physical protection systems at nuclear facilities, as well as in facility safety systems, instrumentation, information processing and communication, ''continues to grow and presents an ever more likely target for cyber-attack''. The international nuclear industry is right to take heed of ever-evolving security threats, deal with them accordingly, and be as open and transparent as security allows about what is being done, which will reassure the general public. However, the potential menace of cyberspace should not be allowed to become such a distraction that it gives those who are ideologically opposed to nuclear another stick with which to beat the industry.
Potential of low-temperature nuclear heat applications
International Nuclear Information System (INIS)
1986-12-01
At present, more than one third of the fossil fuel currently used is being consumed to produce space heating and to meet industrial needs in many countries of the world. Imported oil still represents a large portion of this fossil fuel and despite its present relatively low price future market evolutions with consequent upward cost revisions cannot be excluded. Thus the displacement of the fossil fuel by cheaper low-temperature heat produced in nuclear power plants is a matter which deserves careful consideration. Technico-economic studies in many countries have shown that the use of nuclear heat is fully competitive with most of fossil-fuelled plants, the higher investment costs being offset by lower production cost. Another point in favour of heat generation by nuclear source is its indisputable advantage in terms of benefits to the environment. The IAEA activity plans for 1985-86 concentrate on information exchange with specific emphasis on the design criteria, operating experience, safety requirements and specifications of heat-only reactors, co-generation plants and existing power plants backfitted for additional heat applications. The information gained up to 1985 was discussed during the Advisory Group Meeting on the Potential of Low-Temperature Nuclear Heat Applications held in the Federal Institute for Reactor Research, Wuerenlingen, Switzerland in September 1985 and, is included in the present Technical Document
Energy Technology Data Exchange (ETDEWEB)
Chau, H.T.P
2002-10-01
One of the main goals of classical and quantum physics is to solve the many-body problem. In nuclear theory, several methods have been developed and provide accurate results. In this thesis, we remind how symmetry can be used to obtain analytical solutions of the quantum many-body problem. We emphasize that unitary Lie algebras play a crucial role in quantum mechanics and propose and implement a method to build irreducible representations of this algebra from its highest-weight state. Calculations of bosonic and fermionic spectra are performed with realistic and with random interactions. Studies with rotational invariant two-body random interactions have unveiled high degree of order (a marked statistical preference is found for ground states with angular momentum equal to zero). In the second chapter of this thesis, it is argued that the spectral properties of this kind of interaction depend on the choice of the valence space. In particular, we propose a geometrical method to predict the properties of the ground state in certain cases. We also present numerical results when the geometrical approach can not be applied. In the third chapter, we study the link between quantum chaos and nuclear spectra calculated with realistic interactions. (author)
Löschberger, Anna; van de Linde, Sebastian; Dabauvalle, Marie-Christine; Rieger, Bernd; Heilemann, Mike; Krohne, Georg; Sauer, Markus
2012-02-01
One of the most complex molecular machines of cells is the nuclear pore complex (NPC), which controls all trafficking of molecules in and out of the nucleus. Because of their importance for cellular processes such as gene expression and cytoskeleton organization, the structure of NPCs has been studied extensively during the last few decades, mainly by electron microscopy. We have used super-resolution imaging by direct stochastic optical reconstruction microscopy (dSTORM) to investigate the structure of NPCs in isolated Xenopus laevis oocyte nuclear envelopes, with a lateral resolution of ~15 nm. By generating accumulated super-resolved images of hundreds of NPCs we determined the diameter of the central NPC channel to be 41 ± 7 nm and demonstrate that the integral membrane protein gp210 is distributed in an eightfold radial symmetry. Two-color dSTORM experiments emphasize the highly symmetric NPCs as ideal model structures to control the quality of corrections to chromatic aberration and to test the capability and reliability of super-resolution imaging methods.
Symmetry chains and adaptation coefficients
International Nuclear Information System (INIS)
Fritzer, H.P.; Gruber, B.
1985-01-01
Given a symmetry chain of physical significance it becomes necessary to obtain states which transform properly with respect to the symmetries of the chain. In this article we describe a method which permits us to calculate symmetry-adapted quantum states with relative ease. The coefficients for the symmetry-adapted linear combinations are obtained, in numerical form, in terms of the original states of the system and can thus be represented in the form of numerical tables. In addition, one also obtains automatically the matrix elements for the operators of the symmetry groups which are involved, and thus for any physical operator which can be expressed either as an element of the algebra or of the enveloping algebra. The method is well suited for computers once the physically relevant symmetry chain, or chains, have been defined. While the method to be described is generally applicable to any physical system for which semisimple Lie algebras play a role we choose here a familiar example in order to illustrate the method and to illuminate its simplicity. We choose the nuclear shell model for the case of two nucleons with orbital angular momentum l = 1. While the states of the entire shell transform like the smallest spin representation of SO(25) we restrict our attention to its subgroup SU(6) x SU(2)/sub T/. We determine the symmetry chains which lead to total angular momentum SU(2)/sub J/ and obtain the symmetry-adapted states for these chains
Molecular symmetry and spectroscopy
Bunker, Philip; Jensen, Per
2006-01-01
The first edition, by P.R. Bunker, published in 1979, remains the sole textbook that explains the use of the molecular symmetry group in understanding high resolution molecular spectra. Since 1979 there has been considerable progress in the field and a second edition is required; the original author has been joined in its writing by Per Jensen. The Material of the first edition has been reorganized and much has been added. The molecular symmetry group is now introduced early on, and the explanation of how to determine nuclear spin statistical weights has been consolidated in one chapter, after groups, symmetry groups, character tables and the Hamiltonian have been introduced. A description of the symmetry in the three-dimensional rotation group K(spatial), irreducible spherical tensor operators, and vector coupling coefficients is now included. The chapters on energy levels and selection rules contain a great deal of material that was not in the first edition (much of it was undiscovered in 1979), concerning ...
Directory of Open Access Journals (Sweden)
Kirstin Peters
2010-11-01
Full Text Available A well-known result by Palamidessi tells us that πmix (the π-calculus with mixed choice is more expressive than πsep (its subset with only separate choice. The proof of this result argues with their different expressive power concerning leader election in symmetric networks. Later on, Gorla offered an arguably simpler proof that, instead of leader election in symmetric networks, employed the reducibility of incestual processes (mixed choices that include both enabled senders and receivers for the same channel when running two copies in parallel. In both proofs, the role of breaking (initial symmetries is more or less apparent. In this paper, we shed more light on this role by re-proving the above result - based on a proper formalization of what it means to break symmetries without referring to another layer of the distinguishing problem domain of leader election. Both Palamidessi and Gorla rephrased their results by stating that there is no uniform and reasonable encoding from πmix into πsep. We indicate how the respective proofs can be adapted and exhibit the consequences of varying notions of uniformity and reasonableness. In each case, the ability to break initial symmetries turns out to be essential.
Majlesi, A.; Roohani Ghehsareh, H.; Zaghian, A.
2017-12-01
In this study, the Lie symmetry analysis is performed on a coupled system of nonlinear time-fractional Jaulent-Miodek equations associated with energy-dependent Schrödinger potential. The underlying problem is similarity reduced to a system of nonlinear ordinary differential equations with Erdelyi-Kober fractional derivatives. Employing the invariant subspace method, a set of explicit solutions for the problem has been well constructed. In addition, the new conservation theorem is used to construct the conservation laws of the problem.
Expected brine movement at potential nuclear waste repository salt sites
International Nuclear Information System (INIS)
McCauley, V.S.; Raines, G.E.
1987-08-01
The BRINEMIG brine migration code predicts rates and quantities of brine migration to a waste package emplaced in a high-level nuclear waste repository in salt. The BRINEMIG code is an explicit time-marching finite-difference code that solves a mass balance equation and uses the Jenks equation to predict velocities of brine migration. Predictions were made for the seven potentially acceptable salt sites under consideration as locations for the first US high-level nuclear waste repository. Predicted total quantities of accumulated brine were on the order of 1 m 3 brine per waste package or less. Less brine accumulation is expected at domal salt sites because of the lower initial moisture contents relative to bedded salt sites. Less total accumulation of brine is predicted for spent fuel than for commercial high-level waste because of the lower temperatures generated by spent fuel. 11 refs., 36 figs., 29 tabs
Dark discrete gauge symmetries
International Nuclear Information System (INIS)
Batell, Brian
2011-01-01
We investigate scenarios in which dark matter is stabilized by an Abelian Z N discrete gauge symmetry. Models are surveyed according to symmetries and matter content. Multicomponent dark matter arises when N is not prime and Z N contains one or more subgroups. The dark sector interacts with the visible sector through the renormalizable kinetic mixing and Higgs portal operators, and we highlight the basic phenomenology in these scenarios. In particular, multiple species of dark matter can lead to an unconventional nuclear recoil spectrum in direct detection experiments, while the presence of new light states in the dark sector can dramatically affect the decays of the Higgs at the Tevatron and LHC, thus providing a window into the gauge origin of the stability of dark matter.
Adducin family proteins possess different nuclear export potentials
Liu, Chia-Mei; Hsu, Wen-Hsin; Lin, Wan-Yi; Chen, Hong-Chen
2017-01-01
Background The adducin (ADD) family proteins, namely ADD1, ADD2, and ADD3, are actin-binding proteins that play important roles in the stabilization of membrane cytoskeleton and cell-cell junctions. All the ADD proteins contain a highly conserved bipartite nuclear localization signal (NLS) at the carboxyl termini, but only ADD1 can localize to the nucleus. The reason for this discrepancy is not clear. Methods To avoid the potential effect of cell-cell junctions on the distribution of ADD prot...
The potential for disruptive innovations in nuclear power
International Nuclear Information System (INIS)
Adams, F.P.
2014-01-01
The concept of 'disruptive innovation' is a management tool that provides a framework for understanding the structure and dynamics of technology markets, especially their sometimes acute response to innovation. The concept was used in a preliminary assessment of a number of energy technologies, including renewable energy technologies and energy storage, as well as nuclear technologies, as they interact in industry and the marketplace. The technologies were assessed and perspectives were provided on their current potential for innovation to disrupt the value networks behind electricity markets. The findings indicate that this concept may provide useful guidance for the planning of technology development. (author)
International Nuclear Information System (INIS)
1995-01-01
The report defines potential exposure in terms of probability of its occurrence and possible consequences. Individual risk is expressed as the probability of the exposure and the conditional probability of death resulting from the exposure. Societal risk is more than the sum of individual risks. This report explores the relationship between individual risk and societal risk and the relevant criteria. For accidents causing serious damage to a nuclear power plant or having off-site consequences, individual risk is not sufficiently limiting because of the many aspects of societal impact. The approach to dealing with potential exposures in nuclear safety results in risks that are consistent with or more stringent than the ICRP's recommendations in its recent publications. 10 refs
Indirect recoil implantation following nuclear reactions: Theory and potential applications
International Nuclear Information System (INIS)
Conlon, T.W.
1980-01-01
A general treatment of indirect recoil implantation following nuclear reactions is given for the first time. This method allows implantation into any substrate of a wide range of species produced by nuclear reactions either in a thin sacrificial target or from a solid target. It is demonstrated that this can be done whilst avoiding primary beam damage to the substrate. Two cases are considered, the general one in which non-elastic nuclear reactions produce the recoil species of interest and secondly the special case of elastic recoils. In both cases a number of novel features of the process not previously described are outlined. For example, by controlling the angular acceptance of the substrate for recoil products the method can be tailored to give well controlled implantation profiles very similar to direct implantation (i.e., approximately Gaussian in range) or more extensive depth distributions whose profiles are simply determined by the centre of mass angular distribution of the reaction product. The flux of particles available for implantation is approximately 10 -4 smaller than from direct implantation facilities, but is comparable to the useful implantation dose achieved by the established technique of direct elastic recoil implantation. The radiation damage is little more than that associated with the indirect implant itself in contrast to direct elastic recoil implantation where the potential damage produced often mediates against the use of that technique. The main advantage of this relatively new method over the conventional methods is the wider range of species which can be implanted with minimum damage to the substrate. These include elements which cannot be conveniently produced from ion sources as well as exotic species which cannot be produced other than by nuclear reactions; radioactive species are good examples of both cases. (orig.)
Underground siting of nuclear power plants: potential benefits and penalties
International Nuclear Information System (INIS)
Allensworth, J.A.; Finger, J.T.; Milloy, J.A.; Murfin, W.B.; Rodeman, R.; Vandevender, S.G.
1977-08-01
The potential for improving nuclear power safety is analyzed by siting plants underground in mined cavities or by covering plants with fill earth after construction in an excavated cut. Potential benefits and penalties of underground plants are referenced to analogous plants located on the surface. Three representative regional sites having requisite underground geology were used to evaluate underground siting. The major factors which were evaluated for all three sites were: (1) containment of radioactive materials, (2) transport of groundwater contamination, and (3) seismic vulnerability. External protection, plant security, feasibility, operational considerations, and cost were evaluated on a generic basis. Additionally, the national availability of sites having the requisite geology for both underground siting concepts was determined
International Nuclear Information System (INIS)
Xu Chang; Li Baoan; Chen Liewen
2010-01-01
Based on the Hugenholtz-Van Hove theorem, it is shown that both the symmetry energy E sym (ρ) and its density slope L(ρ) at normal density ρ 0 are completely determined by the nucleon global optical potentials. The latter can be extracted directly from nucleon-nucleus scatterings, (p,n) charge-exchange reactions, and single-particle energy levels of bound states. Averaging all phenomenological isovector nucleon potentials constrained by world data available in the literature since 1969, the best estimates of E sym (ρ 0 )=31.3 MeV and L(ρ 0 )=52.7 MeV are simultaneously obtained. Moreover, the corresponding neutron-proton effective mass splitting in neutron-rich matter of isospin asymmetry δ is estimated to be (m n * -m p * )/m=0.32δ.
Current assessment and future potential of the international nuclear market
International Nuclear Information System (INIS)
Cassidy, P.R.
1983-01-01
This is a study of the current and future situation of the international nuclear market. This paper highlights the projections as seen not only by Bechtel Power Corporation, but also by the international nuclear community. It covers in particular the electric power growth projection; the percentage of probable nuclear power generation; operating services for existing nuclear power plants; and the nuclear fuel cycle. (NEA) [fr
Rugari, Steven Louis
1992-01-01
We have carried out a search for broken reflection symmetry in the exotic nucleus ^{114 }Xe. Evidence for broken reflection symmetry has been previously observed in the actinide region, most notably Ra-Th nuclei, and more recently in the neutron rich nuclei ^{144}Ba, ^{146}Ce, and ^{146,148}Nd. This evidence has been discussed in terms of two conceptually different theoretical frameworks, namely alpha clustering and octupole deformation. The alpha clustering model makes global predictions of the relative strengths of enhanced electric dipole (E1) transitions characteristic of broken reflection symmetry, and predicts a dependence on isospin divided by nuclear mass (N-Z) ^2/A^2 of the reduced transition probability, B(E1), where A is the nuclear mass number and N and Z are, respectively, the neutron and proton number. The nuclei studied previously have approximately the same value of (N-Z)^2/A ^2 between 0.033 and 0.05. In ^ {114}Xe this parameter is much different, (N-Z)^2/A^2 =.0028, allowing for a test of the prediction. On the other hand, the octupole model description is less straightforward. Two terms contributing to the calculation of reduced transition strengths are based on the collective liquid drop model of nuclei and have a global dependence on A^2 Z^2. A third term, however, depends explicitly on the shell model description of the valence nucleons and can be large enough to remove this global dependence. The nucleus ^{114}Xe was produced in the heavy ion fusion evaporation reaction ^{60}Ni(^ {58}Ni,2p2n)^{114 }Xe in two separate measurements at Daresbury Laboratory and at Yale University. The nucleus was identified by means of a recoil mass spectrometer in the first reaction and by detection of evaporated neutrons in the second. Gamma ray spectra were collected in coincidence with these triggers using similar gamma detector setups. Information on the angular distributions of the gamma rays was collected for at least three separate angles in each
Neural networks and their potential application in nuclear power plants
International Nuclear Information System (INIS)
Uhrig, R.E.
1991-01-01
A neural network is a data processing system consisting of a number of simple, highly interconnected processing elements in an architecture inspired by the structure of the cerebral cortex portion of the brain. Hence, neural networks are often capable of doing things which humans or animals do well but which conventional computers often do poorly. Neural networks have emerged in the past few years as an area of unusual opportunity for research, development and application to a variety of real world problems. Indeed, neural networks exhibit characteristics and capabilities not provided by any other technology. Examples include reading Japanese Kanji characters and human handwriting, reading a typewritten manuscript aloud, compensating for alignment errors in robots, interpreting very noise signals (e.g., electroencephalograms), modeling complex systems that cannot be modeled mathematically, and predicting whether proposed loans will be good or fail. This paper presents a brief tutorial on neural networks and describes research on the potential applications to nuclear power plants
Classical properties and semiclassical quantization of a spherical nuclear potential
International Nuclear Information System (INIS)
Carbonell, J.; Brut, F.; Arvieu, R.; Touchard, J.
1984-03-01
The geometrical properties of the classical energy-action surface are studied for a nuclear Woods-Saxon-like spherical potential, in connection with the E.B.K. semiclassical method of quantization. Comparisons are made with other well known cases: the spherical harmonic oscillator and the spherical billiard. The shift of single particle energies from A = 208 to A = 16 is calculated by a simple method inspired by the Erhenfest adiabatic invariants. Semiclassical results are then compared with exact Schroedinger energies. It is seen that the most significant features of the single particle spectrum are explained by local properties of the energy action surface (curvature, slope) and by their evolution with the particle number
Classical properties and semiclassical quantisation of a spherical nuclear potential
International Nuclear Information System (INIS)
Carbonell, J.; Brut, F.; Arvieu, R.; Touchard, J.
1985-01-01
The geometrical properties of the classical energy-action surface are studied for a nuclear Woods-Saxon-like spherical potential in connection with the EBK semiclassical method of quantisation. Comparisons are made with other well known cases: the spherical harmonic oscillator and the spherical billiard. The shift of single-particle energies from A=208 to A=16 is calculated by a simple method inspired by the Erhenfest adiabatic invariants. Semiclassical results are then compared with exact Schroedinger energies. It is seen that the most significant features of the single-particle spectrum are explained by local properties of the energy-action surface (curvature, slope) and by their evolution with particle number. (author)
Some studies in scatering by Coulomb modified nuclear potentials
International Nuclear Information System (INIS)
Laha, U.
1988-01-01
Recently, there has been a surge of interest in theoretical questions concerning the Coulomb nuclear problems with the main emphasis on their off-shell behaviour. Earlier approaches to the problem made use of a version of the two-potential formula as used by Bajzer. A slightly different point of view is presented here. An expression for the interacting Green's function for motion in the Coulomb plus Graz potential is constructed and used to obtain the half-off-shell T matrix in the ''maximal reduced form''. Similar results were also derived for the off-shell Jost functions. It is explicitly demonstrated that Coulomb and Coulomb-like potentials the half-off-shell T matrix can be expressed in terms of on-and off-shell Jost functions in the same way as one does for a purely short range interaction. In presenting the results for T matrix and other related quantities, the Coulomb effect is included rigorously. Results clearly delineate the branch point singularities originating from the long range nature of the Coulomb interaction and thus provide a better understanding of the off-shell two-body Coulomb-like T matrices. It is hoped that these results will form an adequate starting point for rigorous calculations on few-body systems with charges. (author). 16 refs
Neural networks and their potential application to nuclear power plants
International Nuclear Information System (INIS)
Uhrig, R.E.
1991-01-01
A network of artificial neurons, usually called an artificial neural network is a data processing system consisting of a number of highly interconnected processing elements in an architecture inspired by the structure of the cerebral cortex portion of the brain. Hence, neural networks are often capable of doing things which humans or animals do well but which conventional computers often do poorly. Neural networks exhibit characteristics and capabilities not provided by any other technology. Neural networks may be designed so as to classify an input pattern as one of several predefined types or to create, as needed, categories or classes of system states which can be interpreted by a human operator. Neural networks have the ability to recognize patterns, even when the information comprising these patterns is noisy, sparse, or incomplete. Thus, systems of artificial neural networks show great promise for use in environments in which robust, fault-tolerant pattern recognition is necessary in a real-time mode, and in which the incoming data may be distorted or noisy. The application of neural networks, a rapidly evolving technology used extensively in defense applications, alone or in conjunction with other advanced technologies, to some of the problems of operating nuclear power plants has the potential to enhance the safety, reliability and operability of nuclear power plants. The potential applications of neural networking include, but are not limited to diagnosing specific abnormal conditions, identification of nonlinear dynamics and transients, detection of the change of mode of operation, control of temperature and pressure during start-up, signal validation, plant-wide monitoring using autoassociative neural networks, monitoring of check valves, modeling of the plant thermodynamics, emulation of core reload calculations, analysis of temporal sequences in NRC's ''licensee event reports,'' and monitoring of plant parameters
Nonlinear electromagnetic fields and symmetries
Barjašić, Irena; Gulin, Luka; Smolić, Ivica
2017-06-01
We extend the classical results on the symmetry inheritance of the canonical electromagnetic fields, described by the Maxwell's Lagrangian, to a much wider class of models, which include those of the Born-Infeld, power Maxwell and the Euler-Heisenberg type. Symmetry inheriting fields allow the introduction of electromagnetic scalar potentials and these are proven to be constant on the Killing horizons. Finally, using the relations obtained along the analysis, we generalize and simplify the recent proof for the symmetry inheritance of the 3-dimensional case, as well as give the first constraint for the higher dimensional electromagnetic fields.
Risks of potential accidents of nuclear power plants in Europe
Slaper H; Eggink GJ; Blaauboer RO
1993-01-01
Over 200 nuclear power plants for commercial electricity production are presently operational in Europe. The 1986 accident with the nuclear power plant in Chernobyl has shown that severe accidents with a nuclear power plant can lead to a large scale contamination of Europe. This report is focussed
Nuclear power development in Guangdong, China - Potential conditions and program
International Nuclear Information System (INIS)
Yun Qing, MA
1996-01-01
China enjoys excellent and broad prospects for developing nuclear power. The nuclear power development program in Guangdong province is aggressive and grand featuring an enormous demand for nuclear power. CGNPC has already gained considerable experience and expertise in operating, constructing and managing nuclear power stations, and will play a pivotal role in developing nuclear power in Guangdong in the future CGNPC needs and is also willing to make every effort to develop cooperative relationship in Asia and the Pacific regions, and has already taken steps to strengthen and expand this kind of cooperation
Microscopic basis of collective symmetries
International Nuclear Information System (INIS)
Arima, A.
1983-01-01
The seniority scheme of SU(2) symmetry in a single closed shell is an interaction to conserve seniority. It is suggested that an interaction simpler than delta interaction can be used to study the level structure of Pb isotopes. The concept of seniority number is introduced. Reduction formulae are then derived for one-body operators. Conservation of seniority in a single closed shell is treated. SU(6) symmetry of nuclear collective motion, or the SU(6) invariance of the boson system, is derived
Chiral symmetry and chiral-symmetry breaking
International Nuclear Information System (INIS)
Peskin, M.E.
1982-12-01
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed
Potential cooperative measures on nuclear issues in Asia
International Nuclear Information System (INIS)
Olsen, J.
1997-01-01
Cooperation on nuclear issues is receiving increased attention in Asia. In Northeast Asia, where the nuclear industry is well-developed, cooperation in the back end of the nuclear fuel cycle could help deal with issues such as disposition of spent fuel and long term storage options. In Southeast Asia, where countries are just beginning to introduce nuclear energy, cooperation would be useful in developing standards for the nuclear industry. Throughout Asia, nuclear research and power activities can raise concerns about safety, environmental pollution and proliferation. The sharing of relevant information, i.e. cooperative monitoring, will be essential to addressing these issues. In fact, a number of regional interactions on nuclear issues are already occurring. These range from training exchanges sponsored by the more advanced states to participation in environmental monitoring of the East Sea (Sea of Japan). Several states are considering sharing information from their nuclear facilities; some exchanges of radiation data are already in place. The KEDO reactor project will involve close working relations between the nuclear experts of South Korea, North Korea, Japan, and the US. Areas for further regional cooperation are discussed
Pseudospin symmetry and the relativistic harmonic oscillator
International Nuclear Information System (INIS)
Lisboa, R.; Malheiro, M.; Castro, A.S. de; Alberto, P.; Fiolhais, M.
2004-01-01
A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonian contains a scalar S and a vector V quadratic potentials in the radial coordinate, as well as a tensor potential U linear in r. Setting either or both combinations Σ=S+V and Δ=V-S to zero, analytical solutions for bound states of the corresponding Dirac equations are found. The eigenenergies and wave functions are presented and particular cases are discussed, devoting a special attention to the nonrelativistic limit and the case Σ=0, for which pseudospin symmetry is exact. We also show that the case U=Δ=0 is the most natural generalization of the nonrelativistic harmonic oscillator. The radial node structure of the Dirac spinor is studied for several combinations of harmonic-oscillator potentials, and that study allows us to explain why nuclear intruder levels cannot be described in the framework of the relativistic harmonic oscillator in the pseudospin limit
Anticipating Potential Waste Acceptance Criteria for Defense Spent Nuclear Fuel
International Nuclear Information System (INIS)
Rechard, R.P.; Lord, M.E.; Stockman, C.T.; McCurley, R.D.
1997-01-01
The Office of Environmental Management of the U.S. Department of Energy is responsible for the safe management and disposal of DOE owned defense spent nuclear fuel and high level waste (DSNF/DHLW). A desirable option, direct disposal of the waste in the potential repository at Yucca Mountain, depends on the final waste acceptance criteria, which will be set by DOE's Office of Civilian Radioactive Waste Management (OCRWM). However, evolving regulations make it difficult to determine what the final acceptance criteria will be. A method of anticipating waste acceptance criteria is to gain an understanding of the DOE owned waste types and their behavior in a disposal system through a performance assessment and contrast such behavior with characteristics of commercial spent fuel. Preliminary results from such an analysis indicate that releases of 99Tc and 237Np from commercial spent fuel exceed those of the DSNF/DHLW; thus, if commercial spent fuel can meet the waste acceptance criteria, then DSNF can also meet the criteria. In large part, these results are caused by the small percentage of total activity of the DSNF in the repository (1.5%) and regulatory mass (4%), and also because commercial fuel cladding was assumed to provide no protection
Jaffé, Hans H
1977-01-01
This book, devoted exclusively to symmetry in chemistry and developed in an essentially nonmathematical way, is a must for students and researchers. Topics include symmetry elements and operations, multiple symmetry operations, multiplication tables and point groups, group theory applications, and crystal symmetry. Extensive appendices provide useful tables.
Nuclear Education and Training Programs of Potential Interest to Utilities.
Atomic Energy Commission, Washington, DC.
This compilation of education and training programs related to nuclear applications in electric power generation covers programs conducted by nuclear reactor vendors, public utilities, universities, technical institutes, and community colleges, which were available in December 1968. Several training-program consultant services are also included.…
Constraining potential nuclear-weapons proliferation from civilian reactors
International Nuclear Information System (INIS)
Travelli, A.; Gaines, L.L.; Minkov, V.; Olson, A.P.; Snelgrove, J.
1993-01-01
Cessation of the Cold War and renewed international attention to the proliferation of weapons of mass destruction are leading to national policies aimed at restraining nuclear-weapons proliferation that could occur through the nuclear-fuel cycle. Argonne, which has unique experience, technology, and capabilities, is one of the US national laboratories contributing to this nonproliferation effort
Kootstra, Gert; Nederveen, Arco; de Boer, Bart
2008-01-01
Humans are very sensitive to symmetry in visual patterns. Symmetry is detected and recognized very rapidly. While viewing symmetrical patterns eye fixations are concentrated along the axis of symmetry or the symmetrical center of the patterns. This suggests that symmetry is a highly salient feature. Existing computational models of saliency, however, have mainly focused on contrast as a measure of saliency. These models do not take symmetry into account. In this paper, we discuss local symmet...
Nuclear installations abroad the accident risks and their potential consequences
International Nuclear Information System (INIS)
Turvey, F.J.
1996-01-01
This paper endeavors to assess the threat to Ireland from severe accidents at civil nuclear installations. Among the various types of nuclear installations worldwide, reactors and reprocessing plants are considered to be the most threatening and so the paper focuses on these. The threat is assumed to be a function of the risk of severe accidents at the above types of installations and the probability of unfavourable weather conditions carrying the radioactive releases to Ireland. Although nuclear installations designed in eastern Europe and Asia are less safe than others, the greatest threat to Ireland arises from nearby installations in the UK. The difficulty of measuring the probabilities and consequences of severe nuclear accidents at nuclear installations in general is explained. In the case of the UK installations, this difficulty is overcome to some degree by using values of 'tolerable' risk adopted by the national nuclear regulator to define the radiotoxic releases from nuclear accidents. These are used as input to atmospheric dispersion models in which unfavourable weather conditions for Ireland are assumed and radiation doses are calculated to members of the Irish public. No countermeasures, such as sheltering, are assumed. In the worst cast scenario no deaths would be expected in Ireland in the immediate aftermath of the accident however, an increase in cancers over a period of 25 years or so would be expected assuming present-day models for the effect of low level radiation are valid
Nguyen, Hieu T T; Le, Hung M
2012-05-10
The classical interchange (permutation) of atoms of similar identity does not have an effect on the overall potential energy. In this study, we present feed-forward neural network structures that provide permutation symmetry to the potential energy surfaces of molecules. The new feed-forward neural network structures are employed to fit the potential energy surfaces for two illustrative molecules, which are H(2)O and ClOOCl. Modifications are made to describe the symmetric interchange (permutation) of atoms of similar identity (or mathematically, the permutation of symmetric input parameters). The combined-function-derivative approximation algorithm (J. Chem. Phys. 2009, 130, 134101) is also implemented to fit the neural-network potential energy surfaces accurately. The combination of our symmetric neural networks and the function-derivative fitting effectively produces PES fits using fewer numbers of training data points. For H(2)O, only 282 configurations are employed as the training set; the testing root-mean-squared and mean-absolute energy errors are respectively reported as 0.0103 eV (0.236 kcal/mol) and 0.0078 eV (0.179 kcal/mol). In the ClOOCl case, 1693 configurations are required to construct the training set; the root-mean-squared and mean-absolute energy errors for the ClOOCl testing set are 0.0409 eV (0.943 kcal/mol) and 0.0269 eV (0.620 kcal/mol), respectively. Overall, we find good agreements between ab initio and NN prediction in term of energy and gradient errors, and conclude that the new feed-forward neural-network models advantageously describe the molecules with excellent accuracy.
Pseudospin Symmetry as a Bridge between Hadrons and Nuclei
Directory of Open Access Journals (Sweden)
Joseph N. Ginocchio
2016-03-01
Full Text Available Atomic nuclei exhibit approximate pseudospin symmetry. We review the arguments that this symmetry is a relativistic symmetry. The condition for this symmetry is that the sum of the vector and scalar potentials in the Dirac Hamiltonian is a constant. We give the generators of pseudospin symmetry. We review some of the predictions that follow from the insight that pseudospin symmetry has relativistic origins . We show that approximate pseudospin symmetry in nuclei predicts approximate spin symmetry in anti-nucleon scattering from nuclei. Since QCD sum rules predict that the sum of the scalar and vector potentials is small, we discuss the quark origins of pseudospin symmetry in nuclei and spin symmetry in hadrons.
Status and potential of nuclear energy in Pakistan
International Nuclear Information System (INIS)
Khan, A.M.; Jalal, A.I.
1991-01-01
Pakistan is an energy resource deficient country which is heavily dependent on imported energy, while its per capita energy consumption level is still very low. Energy and electricity needs have been growing rapidly and these trends are expected to continue. Pakistan needs to make use of nuclear power on a large scale. This paper discusses the limitations of indigenous energy resources in coping with the future requirements of electricity and compares the cost economics of nuclear power with that of electricity generation based on imported oil and coal. It then describes the efforts being made in the country to make use of nuclear power in a self-reliant manner. (author)
Whistleblower litigation: A potential explosion in the nuclear industry
International Nuclear Information System (INIS)
Kowitt, A.J.; Panich, D.
1990-01-01
This article examines the protection offered nuclear employees and the limits of a nuclear employer's liability under section 210 of the Energy Reorganization Act. The author's warn that review by the US Supreme Court is not necessary but could only serve to expose the nuclear industry to an onslaught of litigation resulting from the assertion by an employee subjected to an adverse employment decision that the employee was engaged in a protected activity and as a result has a right to protection from retaliation by the employer
Nonlocal Symmetries to Systems of Nonlinear Diffusion Equations
International Nuclear Information System (INIS)
Qu Changzheng; Kang Jing
2008-01-01
In this paper, we study potential symmetries to certain systems of nonlinear diffusion equations. Those systems have physical applications in soil science, mathematical biology, and invariant curve flows in R 3 . Lie point symmetries of the potential system, which cannot be projected to vector fields of the given dependent and independent variables, yield potential symmetries. The class of the system that admits potential symmetries is expanded.
Potential Russian Nuclear Contingencies in the Caucasus: Implications for NATO
National Research Council Canada - National Science Library
Wagner, Thomas
2000-01-01
...; and a conflict involving Turkey. The Caucasus is the region in which it is most plausible that Russia might resort to nuclear weapons in extreme circumstances This region has been in turmoil since the collapse of the Soviet Union...
Scalar symmetry of the massless Dirac equation
International Nuclear Information System (INIS)
Clerk, G.J.; McKellar, B.H.J.
1992-01-01
The existence of a symmetry of the Dirac equation for a massless particle in a scalar field is demonstrated, and its effect on the band structure of certain arrays of scalar δ-function potentials is investigated. The implications of the symmetry for more general scalar potentials are also discussed. 10 refs
Prospect and potential of nuclear power plants in Indonesia
International Nuclear Information System (INIS)
Subki, I.R.; Adiwardojo; Kasim, M.S.; Iskandar, A.; Mulyanto
1997-01-01
In line with the national energy policy of Indonesia in promoting the intensification, diversification and conversation of energy, some important steps need to be taken in order to establish alternative energy strategies which will be decisive in the formulation and development of the national energy plan in the future. At present, Indonesia does not have any nuclear power plants. The introduction of nuclear power In Indonesia is not only to reach an optimum energy mix based on costs and the environment, but also to relieve the pressure arising from increasing domestic demand for oil and gas. This paper addresses the present feasibility study being performed on the introduction of nuclear power plants in Indonesia. It is anticipated that nuclear power will contribute about 10% of Indonesia's electrical supply as of the year 2019. This represents approximately 12,600 MWe in capability. The paper describes the results, to date, of the Feasibility Study on nuclear power including the national energy market analysis, the electricity expansion plan and the associated role of nuclear power, the economics and financial plan, site studies on volcanology, seismology and the environment. (author). 3 refs, 1 fig., 4 tabs
Fábri, Csaba; Quack, Martin; Császár, Attila G
2017-10-07
A discrete-variable-representation-based symmetry adaptation algorithm is presented and implemented in the fourth-age quantum-chemical rotational-vibrational code GENIUSH. The utility of the symmetry-adapted version of GENIUSH is demonstrated by the computation of seven-dimensional bend-only vibrational and rovibrational eigenstates of the highly fluxionally symmetric CH 5 + molecular ion, a prototypical astructural system. While the numerical results obtained and the symmetry labels of the computed rovibrational states of CH 5 + are of considerable utility by themselves, it must also be noted that the present study confirms that the nearly unconstrained motion of the five hydrogen atoms orbiting around the central carbon atom results in highly complex rotational-vibrational quantum dynamics and renders the understanding of the high-resolution spectra of CH 5 + extremely challenging.
A overview of industrial robots and their potential use in the nuclear industry
International Nuclear Information System (INIS)
Larzelere, A.R.; Johnson, J.V.
1992-01-01
To understand the potential uses of industrial robots and the problems in adapting these robots to a nuclear application, the DOE and its design contractors conducted a survey of several manufacturers and users of robotics both in and out of the nuclear industry. This survey was not intended to be a comprehensive review of robotic applications of vendors. This paper provides a brief summary of lessons learned from the survey and the potential uses of commercial industrial robots in nuclear applications
Potential wealth creation via nuclear energy in Malaysia
International Nuclear Information System (INIS)
Sabar Md Hashim; Dol Malek Md Sap
2009-01-01
Like any other developing nation, Malaysia aspires to be an economic force to be reckoned with. A strong opportunity may be in the form of nuclear energy as can be seen from the success stories of France and South Korea. Although nuclear is not the only common parameter that make developed nations tick, the multiplier spin-off impacts of nuclear as sources of wealth creation are deliberated. Foreseeable benefits include job creation (especially highly-skilled knowledge workers), spin-off technologies and vendor development as well as the opportunity to assume regional leadership in carefully-selected sectors. Categorically in Malaysian context, introduction of nuclear energy would yield numerous benefits, i.e. as a strong catalyst to enhance country's competitiveness by raising capacity for knowledge, cutting-edge technology, and eventually, innovation (National Mission Thrust 2) beside ensuring stable electricity generation price; as an element to move up value chain by creating high-skilled knowledge workers who could help to raise country's economic profile and plant the seed for a strong post-2020 Malaysia (National Mission Thrust 1); and as an agent to enhance sustainability and quality of life through clean energy (National Mission Thrust 4) by being environmentally benign due to its low greenhouse gas emissions with very minimal impact to global warming. Our point us that, being synergistic with national aspiration, nuclear energy is a genuine national agenda. (Author)
Nuclear stimulated desorption as a potential tool for surface study
International Nuclear Information System (INIS)
Nir, Dror.
1993-03-01
The described research work constitutes a base for an experimental method to be implemented in the study of solid surfaces. Nuclear Stimulated Desorption (NSD) is a new mode of experimentation in thin film and surface physics. It Is based on the interplay between nuclear phenomena (reactions and spontaneous decays), and atomic - scale induced effects on surfaces and very thin films. One may distinguish between two generically different relationships between the two. First, the dynamics of the nuclear reaction -primarily the recoil of the nucleus - may effect the position of the atom or molecule containing it. Second, the nuclear reaction (or decay) may serve as an analytical indicator of the whereabouts of the atom, or molecule, in question. In nuclear stimulated desorption, both thee aspects combine in an essential way. Namely, one employs a series of two consecutive decays (normally weak decays or isomeric transition) . The first of these decays causes the nucleus to desorb from a surface onto which it had been placed; the second serves to determine the position of the daughter and thereby the characteristics of the primary desorption . The essential feature in NSD is that it occurs almost exclusively from the outermost surface layer. This is because we choose to work with nuclei whose recoil energy Is of the same order of magnitude of the binding energy of the atom to the surface . Furthermore, the desorption probability and its angular (and temporal) characteristics, depend on the features (topology, morphology) of its immediate neighborhood. This work describes experiments which were designed to give relevant, phenomenological information about the outgoing flux of the radioactive daughters (for specifically chosen nuclear species) , and in particular the magnitude of the flux, its time dependence and its charged state. In addition. the basic phenomena itself is being distinguished from competing processes (thermal desorption, in particular). We will now
European energy policy and the potential impact of HTR and nuclear cogeneration
Energy Technology Data Exchange (ETDEWEB)
Fütterer, Michael A., E-mail: michael.fuetterer@ec.europa.eu [European Commission, Joint Research Centre, Institute for Energy and Transport, P.O. Box 2, NL-1755ZG Petten (Netherlands); Carlsson, Johan [European Commission, Joint Research Centre, Institute for Energy and Transport, P.O. Box 2, NL-1755ZG Petten (Netherlands); Groot, Sander de [Nuclear Research and consultancy Group, NL-1755ZG Petten (Netherlands); Deffrennes, Marc [European Commission, DG ENER, L-2530 Luxembourg (Luxembourg); Bredimas, Alexandre [LGI Consulting, 13 rue Marivaux, F-75002 Paris (France)
2014-05-01
This paper first provides an update on the current state of play and the potential future role of nuclear energy in Europe. It then describes the EU energy policy tools in the area of nuclear technology. It explains the three-tier strategy of the European nuclear technology platform and its demonstration initiatives, here specifically for nuclear cogeneration and HTR. The paper closes with an outlook on the boundary conditions at which HTR can become attractive for nuclear cogeneration, not only from an energy policy viewpoint but also economically.
European energy policy and the potential impact of HTR and nuclear cogeneration
International Nuclear Information System (INIS)
Fütterer, Michael A.; Carlsson, Johan; Groot, Sander de; Deffrennes, Marc; Bredimas, Alexandre
2014-01-01
This paper first provides an update on the current state of play and the potential future role of nuclear energy in Europe. It then describes the EU energy policy tools in the area of nuclear technology. It explains the three-tier strategy of the European nuclear technology platform and its demonstration initiatives, here specifically for nuclear cogeneration and HTR. The paper closes with an outlook on the boundary conditions at which HTR can become attractive for nuclear cogeneration, not only from an energy policy viewpoint but also economically
Modern tornado design of nuclear and other potentially hazardous facilities
International Nuclear Information System (INIS)
Stevenson, J.D.; Zhao, Y.
1996-01-01
Tornado wind loads and other tornado phenomena, including tornado missiles and differential pressure effects, have not usually been considered in the design of conventional industrial, commercial, or residential facilities in the United States; however, tornado resistance has often become a design requirement for certain hazardous facilities, such as large nuclear power plants and nuclear materials and waste storage facilities, as well as large liquefied natural gas storage facilities. This article provides a review of current procedures for the design of hazardous industrial facilities to resist tornado effects. 23 refs., 19 figs., 13 tabs
Witten, Edward
2018-02-01
In a modern understanding of particle physics, global symmetries are approximate and gauge symmetries may be emergent. This view, which has echoes in condensed-matter physics, is supported by a variety of arguments from experiment and theory.
Symmetry and perturbation theory
Gaeta, Giuseppe
A co-chain map for the G invariant De Rham complex -- New examples of trihamiltonian structures linking different Lenard chains -- Wave propagation in an elastic medium: GDS equations -- Parametric excitation in nonlinear dynamics -- Collisionless action-minimizing trajectories for the equivariant 3-body problem in R2 -- The Lagrangian and Hamiltonian formulations for a special class of non-conservative systems -- Shadowing chains of collision orbits for the elliptic 3-body problem -- Similarity reductions of an optical model -- Fold, transcritical and pitchfork singularities for time-reversible systems -- Homographic three-body motions with positive and negative masses -- Remarks on conformal Killing tensors and separation of variables -- A regularity theory for optimal partition problems -- Lambda and mu-symmetries -- Potential symmetries and linearization of some evolution equations -- Periodic solutions for zero mass nonlinear wave equations -- Fundamental covariants in the invariant theory of Killing tensors -- Global geometry of 3-body trajectories with vanishing angular momentum -- The relation between the topological structure of the set of controllable affine systems and topological structures of the set of controllable homogenuous systems in low dimension -- On preservation of action variables for satellite librations in elliptic orbits with account of solar light pressure -- An explicit solution of the (quantum) elliptic Calogero-Sutherland model -- An application of the Melnikov integral to a restricted three body problem -- Reductions of integrable equations and automorphic Lie algebras -- Geometric reduction of Poisson operators -- Closed manifolds admitting metrics with the same geodesics -- A transcritical-flip bifurcation in a model for a robot-arm -- Alignment and the classification of Lorentz-signature tensors -- Renormalization group symmetry and gas dynamics -- Refined computation of hypernormal forms -- New order reductions for Euler
The Nuclear Disarmament Movement: Politics, Potential, and Strategy
Nebel, Jacob
2012-01-01
Nuclear disarmament is a global ambition and requires collaboration, but who is collaborating, and what are their roles? This paper discusses the role of the American people in the path towards zero. Scholars have discussed at length the historical lessons of the global disarmament movement, and activists have worked to rekindle the movement after…
International Nuclear Information System (INIS)
Nilles, Hans Peter
2012-04-01
Discrete (family) symmetries might play an important role in models of elementary particle physics. We discuss the origin of such symmetries in the framework of consistent ultraviolet completions of the standard model in field and string theory. The symmetries can arise due to special geometrical properties of extra compact dimensions and the localization of fields in this geometrical landscape. We also comment on anomaly constraints for discrete symmetries.
Energy Technology Data Exchange (ETDEWEB)
Nilles, Hans Peter [Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Bonn Univ. (Germany). Physikalisches Inst.; Ratz, Michael [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-04-15
Discrete (family) symmetries might play an important role in models of elementary particle physics. We discuss the origin of such symmetries in the framework of consistent ultraviolet completions of the standard model in field and string theory. The symmetries can arise due to special geometrical properties of extra compact dimensions and the localization of fields in this geometrical landscape. We also comment on anomaly constraints for discrete symmetries.
Wigner's Symmetry Representation Theorem
Indian Academy of Sciences (India)
IAS Admin
This article elucidates the important role the no- tion of symmetry has played in physics. It dis- cusses the proof of one of the important theorems of quantum mechanics, viz., Wigner's Symmetry. Representation Theorem. It also shows how the representations of various continuous and dis- crete symmetries follow from the ...
Rehren, K. -H.
1996-01-01
Weak C* Hopf algebras can act as global symmetries in low-dimensional quantum field theories, when braid group statistics prevents group symmetries. Possibilities to construct field algebras with weak C* Hopf symmetry from a given theory of local observables are discussed.
Symmetry, asymmetry and dissymmetry
International Nuclear Information System (INIS)
Wackenheim, A.; Zollner, G.
1987-01-01
The authors discuss the concept of symmetry and defect of symmetry in radiological imaging and recall the definition of asymmetry (congenital or constitutional) and dissymmetry (acquired). They then describe a rule designed for the cognitive method of automatic evaluation of shape recognition data and propose the use of reversal symmetry [fr
Polynomial Graphs and Symmetry
Goehle, Geoff; Kobayashi, Mitsuo
2013-01-01
Most quadratic functions are not even, but every parabola has symmetry with respect to some vertical line. Similarly, every cubic has rotational symmetry with respect to some point, though most cubics are not odd. We show that every polynomial has at most one point of symmetry and give conditions under which the polynomial has rotational or…
Chiral symmetry and chiral-symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Peskin, M.E.
1982-12-01
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)
''Nuclear Energy - Potential to Substantially Impact California's Energy Use''
International Nuclear Information System (INIS)
Lawrence Livermore National Laboratory
2006-01-01
The use of nuclear power to generate electricity is very widespread today, with about 20% of all U.S. electricity coming from the nation's 103 operating reactors. Worldwide there are over 400 commercial nuclear plants that make a similar contribution percentage-wise. However, all of the current U.S. reactors and most of those elsewhere are relatively old, with no new ones having been started domestically in over two decades and only a few now being built overseas, mostly in Asia. The principal reason for this hiatus in the U.S. is that the cost of electricity from new nuclear plants has been non-competitive with other electricity sources for a long time. The U.S. nuclear-power industry has not been stagnant during this time, however. First, the existing plants themselves are running significantly better than they were twenty years ago, to the extent that the US. reactor fleet is producing about one-third more electricity annually than it was, due largely to improvements in the capacity factors: the plants run more reliably, shut down less often, and the refueling outages take less than half as long as they once did. The safety performance has also improved dramatically, with major improvements in every one of the main indicators of safety. The security of the plants against sabotage or other malevolent acts has always been very strong, and is stronger still after recent upgrades in response to the September 2001 attacks in New York and Washington. Thus the U.S. nuclear-electricity industry has remained dynamic despite the absence of new construction. The U.S. and foreign companies that design reactors and hope someday to sell more of them have also been actively at work--they have developed advanced reactor designs that promise to cost much less to build and to operate, and to have even better safety performance. Several of these advanced designs have received design-certification approvals from the U.S. Nuclear Regulatory Commission, meaning that a utility could
Hashimoto, Masako; Hashimoto, Kanako; Ando, Fumihiko; Kimura, Yoshiaki; Nagase, Keisuke; Arai, Kunizo
2015-01-01
The lower urinary tract symptoms (LUTS) increases with age and can have a significant effect on the quality of life of the patients. Elderly patients, who are often characterized by a decline in physiological functional and polypharmacy, are susceptible to adverse drug reactions to pharmacotherapy. LUTS can also be a side effect of medication. The purpose of this study was to investigate the possible association between the initiation of LUTS-causing drug therapy and the onset of LUTS. Drug dispensing data at the individual level were retrieved from the CISA (Platform for Clinical Information Statistical Analysis: http://www.cisa.jp) database. A retrospective study was conducted by reviewing patients with LUTS who were dispensed drugs that increased the risk of LUTS between April 2011 and March 2012. Prescription sequence symmetry analysis (PSSA) was employed to investigate the associations between the dispensing of medicines of LUTS and that of LUTS-causing drugs. LUTS-causing drugs were frequently dispensed to patients with LUTS. The use of medications potentially contributing to LUTS was associated with polypharmacy [number of prescription drugs:12.13 ± 6.78 (user) vs. 5.67 ± 5.24 (nonuser)] but not patient age [ age: (71.38 ± 13.28 (user) vs. 70.45 ± 14.80 (nonuser)]. Significant adverse drug events were observed the use of donepezil, cyclophosphamide, antiparkinson drugs, antidepressant, diazepam, antipsychotic drugs for peptic ulcer, tiotropium bromide, and opioids. The use of prescription LUTS-causing drugs was correlated with polypharmacy. The adverse drug events associated with LUTS-causing drugs were highly prevalent in elderly patients. To prevent of adverse drug events in patients with LUTS, pharmacists and physicians should regularly review medication lists and reduce the prescribed medicines.
Studies on cluster decay from trans-lead nuclei using different versions of nuclear potentials
Energy Technology Data Exchange (ETDEWEB)
Santhosh, K.P.; Sukumaran, Indu [Kannur University, School of Pure and Applied Physics, Payyanur, Kerala (India)
2017-06-15
The cluster decays from various isotopes of trans-lead nuclei have been studied using 12 different nuclear potentials by evaluating decay half-lives and are then compared with the available experimental data. The study has shown that the barrier penetrability as well as the decay half-lives varies with the nuclear potential used. The standard deviation of the estimated half-lives is also calculated for these twelve nuclear potentials in comparison with the experimental data. The potential Bass 1980 is found to be the most appropriate potential for studying cluster radioactivity as the standard deviation obtained is least. Among the different proximity potential versions; proximity 1977, proximity 1988, proximity 2000, and modified proximity 2000, the minimum standard deviation is for proximity 1988. The Geiger-Nuttall (G-N) plots studied for different cluster emissions from various parents are observed to show linear behavior but with different slopes and intercepts. Again, the G-N plots obtained are linear with different slopes and intercepts when plotted for different nuclear potentials. So it is observed that with the inclusion of different nuclear potentials, the linearity of the G-N plot remains unaltered. Irrespective of the nuclear potential used, the universal curve (log{sub 10}T{sub 1/2} vs. -ln P) studied for various clusters emitted from various parents are obtained as linear with same slope and intercept. (orig.)
Potential applications of neural networks to nuclear power plants
International Nuclear Information System (INIS)
Uhrig, R.E.
1991-01-01
Application of neural networks to the operation of nuclear power plants is being investigated under a US Department of Energy sponsored program at the University of Tennessee. Projects include the feasibility of using neural networks for the following tasks: diagnosing specific abnormal conditions, detection of the change of mode of operation, signal validation, monitoring of check valves, plant-wide monitoring using autoassociative neural networks, modeling of the plant thermodynamics, emulation of core reload calculations, monitoring of plant parameters, and analysis of plant vibrations. Each of these projects and its status are described briefly in this article. The objective of each of these projects is to enhance the safety and performance of nuclear plants through the use of neural networks
Sustainable development - the potential contribution of nuclear energy
International Nuclear Information System (INIS)
Bourdier, Jean-Pierre; Barre, Bertrand; Durret, Louis-Francois
1998-01-01
Sustainable development combines development, durability and sustainability. Energy is crucial for development: it brings work, nutrition, health, security, community, etc. Electrical energy offers the most possibilities for the consumer, particularly as regards the problems of pollution on the site of consumption. Nuclear generation is one of the best ways of producing electricity. Midway between stock energies and flow energies, it has several advantages: low consumption of resources, safety, compactness and cleanliness. Waste is not a specifically nuclear problem: it should be considered in terms of a life cycle analysis; construction, dismantling and functioning have to be assessed. The size of certain energies' contribution to the greenhouse effect is therefore made clear. Reprocessing represents a saving of energy, without environmental or health damage. It contributes to energy control, and therefore to sustainable development
International Nuclear Information System (INIS)
1976-01-01
Information related to Nuclear Energy Centers (NEC) in the U.S. is presented concerning the U.S. electric power system today; electricity demand history and forecasts; history and forecasts of the electric utility industry; regional notes; the status, history, and forecasts of the nuclear role; power plant siting problems and practices; nuclear facilities siting problems and practices; origin and evolution of the nuclear energy center concept; conceptualized description of nuclear energy centers; potential role of nuclear energy centers; assumptions, criteria, and bases; typical evolution of a nuclear energy center; and the nuclear fuel cycle
Potential industrial market for process heat from nuclear reactors
International Nuclear Information System (INIS)
Barnes, R.W.
1976-07-01
A specific segment of industrial process heat use has been examined in detail to identify individual plant locations throughout the United states where nuclear generated steam may be a viable alternative. Five major industries have been studied: paper, chemicals, petroleum, rubber, and primary metals. For these industries, representing 75 percent of the total industrial steam consumption, the individual plant locations within the U.S. using steam in large quantities have been located and characterized as to fuel requirements
Superdeformations and fermion dynamical symmetries
International Nuclear Information System (INIS)
Wu, Cheng-Li
1990-01-01
In this talk, I will present a link between nuclear collective motions and their underlying fermion dynamical symmetries. In particular, I will focus on the microscopic understanding of deformations. It is shown that the SU 3 of the one major shell fermion dynamical symmetry model (FDSM) is responsible for the physics of low and high spins in normal deformation. For the recently observed phenomena of superdeformation, the physics of the problem dictates a generalization to a supershell structure (SFDSM), which also has an SU 3 fermion dynamical symmetry. Many recently discovered feature of superdeformation are found to be inherent in such an SU 3 symmetry. In both cases the dynamical Pauli effect plays a vital role. A particularly noteworthy discovery from this model is that the superdeformed ground band is not the usual unaligned band but the D-pair aligned (DPA) band, which sharply crosses the excited bands. The existence of such DPA band is a key point to understand many properties of superdeformation. Our studies also poses new experimental challenge. This is particularly interesting since there are now plans to build new and exciting γ-ray detecting systems, like the GAMMASPHERE, which could provide answers to some of these challenges. 34 refs., 11 figs., 5 tabs
Risks of potential accidents of nuclear power plants in Europe
International Nuclear Information System (INIS)
Slaper, H.; Eggink, G.J.; Blaauboer, R.O.
1993-12-01
This report is focussed on an integrated assessment of probabilistic cancer mortality risks due to possible accidental releases from the European nuclear power plants. For each of the European nuclear power plants the probability of accidental releases per year of operation is combined with the consequences in terms of the excess doses received over a lifetime (70 years). Risk estimates are restricted to cancer mortality and do not include immediate or short term deaths in the direct vicinity ( -8 per year in Western Europe. Going East the risks increase gradually to over 1000 x 10 -8 per year in regions of the former Soviet Union, where reactors of the Chernobyl type are located. The nuclear power plants in the East European countries dominate the estimated risk pattern and contribute at least 40-50% to the average risk in the West European countries. Improving the reactor safety in eastern European countries could lead to considerable reductions in estimated excess mortality risks. In western Europe the mortality risk might be reduced by a factor of two, and in eastern Europe by a factor of 100 to 1000. (orig.)
Spectral distributions and symmetries
International Nuclear Information System (INIS)
Quesne, C.
1980-01-01
As it is now well known, the spectral distribution method has both statistical and group theoretical aspects which make for great simplifications in many-Fermion system calculations with respect to more conventional ones. Although both aspects intertwine and are equally essential to understand what is going on, we are only going to discuss some of the group theoretical aspects, namely those connected with the propagation of information, in view of their fundamental importance for the actual calculations of spectral distributions. To be more precise, let us recall that the spectral distribution method may be applied in principle to many-Fermion spaces which have a direct-product structure, i.e., are obtained by distributing a certain number n of Fermions over N single-particle states (O less than or equal to n less than or equal to N), as it is the case for instance for the nuclear shell model spaces. For such systems, the operation of a central limit theorem is known to provide us with a simplifying principle which, when used in conjunction with exact or broken symmetries, enables us to make definite predictions in those cases which are not amendable to exact shell model diagonalizations. The distribution (in energy) of the states corresponding to a fixed symmetry is then defined by a small number of low-order energy moments. Since the Hamiltonian is defined in few-particle subspaces embedded in the n-particlespace, the low-order moments, we are interested in, can be expressed in terms of simpler quantities defined in those few-particle subspaces: the information is said to propagate from the simple subspaces to the more complicated ones. The possibility of actually calculating spectral distributions depends upon the finding of simple ways to propagate the information
Reverse-symmetry waveguides: Theory and fabrication
DEFF Research Database (Denmark)
Horvath, R.; Lindvold, Lars René; Larsen, N.B.
2002-01-01
We present an extensive theoretical analysis of reverse-symmetry waveguides with special focus on their potential application as sensor components in aqueous media and demonstrate a novel method for fabrication of such waveguides. The principle of reverse symmetry is based on making the refractive...
Symmetry structure and phase transitions
Indian Academy of Sciences (India)
We study chiral symmetry structure at finite density and temperature in the presence of external magnetic field and .... the case of neutron stars as a function of chemical potential µ associated with finite baryon number density we ..... work expended to create a bubble and are given by Rc = 2σ Ph(T) Pq(T) and Wc = 4πσR2.
Parastatistics and gauge symmetries
International Nuclear Information System (INIS)
Govorkov, A.B.
1982-01-01
A possible formulation of gauge symmetries in the Green parafield theory is analysed and the SO(3) gauge symmetry is shown to be on a distinct status. The Greenberg paraquark hypothesis turns out to be not equivalent to the hypothesis of quark colour SU(3)sub(c) symmetry. Specific features of the gauge SO(3) symmetry are discussed, and a possible scheme where it is an exact subgroup of the broken SU(3)sub(c) symmetry is proposed. The direct formulation of the gauge principle for the parafield represented by quaternions is also discussed
Future perspective of thorium based nuclear fuels and thorium potential of Turkey
International Nuclear Information System (INIS)
Unak, T.; Yildirim, Y.
2001-01-01
Today's nuclear technology has principally been based on the use of fissile U-235 and Pu-239. he existence of thorium in the nature and its potential use in the nuclear technology were not unfortunately into account with a sufficient importance. The global distributions of thorium and uranium reserves indicate that in general some developed countries such as the USA, Canada, Australia, France have considerable uranium reserves, and contrarily only some developing countries such as Turkey, Brazil, India, Egypt have considerable thorium reserves. The studies carried out on the thorium during the last 50 years have clearly showed that the thorium based nuclear fuels have the potential easily use in most of reactor types actually operated with the classical uranium based nuclear fuels without any considerable modification. In the case of the use of thorium based nuclear fuels in future nuclear energy production systems, the serious problems such as the excess of Pu-239, the proliferation potential of nuclear weapons, and also the anxious of nuclear terrorism will probably be resolved, and sustainable nuclear energy production will be realized in the next new century. (authors)
Future perspective of thorium based nuclear fuels and thorium potential of Turkey
International Nuclear Information System (INIS)
Unak, T.; Yildirim, Y.
2000-01-01
Today's nuclear technology has principally been based on the use of fissile U-235 and Pu-239. The existence of thorium in the nature and its potential use in the nuclear technology were not unfortunately into account with a sufficient importance. The global distributions of thorium and uranium reserves indicate that in general some developed countries such as the USA, Canada, Australia, France have considerable uranium reserves, and contrarily only some developing countries such as Turkey, Brazil, India, Egypt have considerable thorium reserves. The studies carried out on the thorium during the last 50 years have clearly showed that the thorium based nuclear fuels have the potential easily use in most of reactor types actually operated with the classical uranium based nuclear fuels without any considerable modification. In the case of the use of thorium based nuclear fuels in future nuclear energy production systems, the serious problems such as the excess of Pu-239, the proliferation potential of nuclear weapons, and also the anxious of nuclear terrorism will probably be resolved, and sustainable nuclear energy production will be realized in the next new century. (authors)
Symmetries of nonlinear ordinary differential equations: The ...
Indian Academy of Sciences (India)
2015-10-21
Oct 21, 2015 ... Lie point symmetries; -symmetries; Noether symmetries; contact symmetries; adjoint symmetries; nonlocal symmetries; hidden symmetries; ... 620 024, India; Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401, India ...
Witten, Edward
2016-03-01
In this talk, I will describe global and gauge symmetries and the interplay between them. The meaning of global symmetries is clear: they act on physical observables. Gauge symmetries are more elusive as they typically do not act on physical observables. Gauge symmetries are redundancies in the mathematical description of a physical system rather than properties of the system itself. The existence of nonperturbative dualities makes it clear that this distinction is unavoidable. Yet in our best understanding the gauge symmetries are deeper. The lepton number symmetries that are probed by the wonderful experimental results that will be reported in this session give an excellent illustration. They are regarded in the Standard Model as indirect consequences of gauge symmetries and they are expected to be only approximate. This expectation is supported by the observation of neutrino oscillations.
International Nuclear Information System (INIS)
Gaiotto, Davide; Kapustin, Anton; Seiberg, Nathan; Willett, Brian
2015-01-01
A q-form global symmetry is a global symmetry for which the charged operators are of space-time dimension q; e.g. Wilson lines, surface defects, etc., and the charged excitations have q spatial dimensions; e.g. strings, membranes, etc. Many of the properties of ordinary global symmetries (q=0) apply here. They lead to Ward identities and hence to selection rules on amplitudes. Such global symmetries can be coupled to classical background fields and they can be gauged by summing over these classical fields. These generalized global symmetries can be spontaneously broken (either completely or to a subgroup). They can also have ’t Hooft anomalies, which prevent us from gauging them, but lead to ’t Hooft anomaly matching conditions. Such anomalies can also lead to anomaly inflow on various defects and exotic Symmetry Protected Topological phases. Our analysis of these symmetries gives a new unified perspective of many known phenomena and uncovers new results.
Chernobyl Nuclear Catastrophe and the High Risk Potential for Mental Retardation.
Holowinsky, Ivan Z.
1993-01-01
This report considers potential effects of the 1986 nuclear explosion at the Chernobyl (Ukraine) nuclear reactor. Approximately 17 million people, of whom 2.5 million were below the age of 5, are thought to have suffered some radioactive contamination. Many of these children are at high risk for mental retardation and learning disorders.…
Potential use of nuclear pumped lasers as fusion drivers
International Nuclear Information System (INIS)
Miley, G.H.; Greenspan, E.; Gilligan, J.
1980-01-01
Recent progress in the development of an energy-storage type nuclear pumped laser (NPL) suitable for laser fusion feedback applications is briefly noted. Then, the use of NPLs in fusion-fission-hybrid systems is presented and analyzed from an energetic point of view. Unique hybrid blanket concepts are proposed that enable approx. 3 fissions in the laser medium per fusion neutron while still providing approx. 2 fissile atoms per fusion neutron. Such designs would enable use of a very low gain fusion device as the driver. (orig.) [de
Molecular Eigensolution Symmetry Analysis and Fine Structure
Directory of Open Access Journals (Sweden)
William G. Harter
2013-01-01
Full Text Available Spectra of high-symmetry molecules contain fine and superfine level cluster structure related to J-tunneling between hills and valleys on rovibronic energy surfaces (RES. Such graphic visualizations help disentangle multi-level dynamics, selection rules, and state mixing effects including widespread violation of nuclear spin symmetry species. A review of RES analysis compares it to that of potential energy surfaces (PES used in Born-Oppenheimer approximations. Both take advantage of adiabatic coupling in order to visualize Hamiltonian eigensolutions. RES of symmetric and D2 asymmetric top rank-2-tensor Hamiltonians are compared with Oh spherical top rank-4-tensor fine-structure clusters of 6-fold and 8-fold tunneling multiplets. Then extreme 12-fold and 24-fold multiplets are analyzed by RES plots of higher rank tensor Hamiltonians. Such extreme clustering is rare in fundamental bands but prevalent in hot bands, and analysis of its superfine structure requires more efficient labeling and a more powerful group theory. This is introduced using elementary examples involving two groups of order-6 (C6 and D3~C3v, then applied to families of Oh clusters in SF6 spectra and to extreme clusters.
The Challenges and Potential of Nuclear Energy for Addressing Climate Change
Energy Technology Data Exchange (ETDEWEB)
Kim, Son H.; Edmonds, James A.
2007-10-24
The response to climate change and the stabilization of atmospheric greenhouse gas concentrations has major implications for the global energy system. Stabilization of atmospheric carbon dioxide (CO2) concentrations requires a peak and an indefinite decline of global CO2 emissions. Nuclear energy, along with other technologies, has the potential to contribute to the growing demand for energy without emitting CO2. Nuclear energy is of particular interest because of its global prevalence and its current significant contribution, nearly 20%, to the world’s electricity supply. We have investigated the value of nuclear energy in addressing climate change, and have explored the potential challenges for the rapid and large-scale expansion of nuclear energy as a response to climate change. The scope of this study is long-term and the modeling time frame extends out a century because the nature of nuclear energy and climate change dictate that perspective. Our results indicate that the value of the nuclear technology option for addressing climate change is denominated in trillions of dollars. Several-fold increases to the value of the nuclear option can be expected if there is limited availability of competing carbon-free technologies, particularly fossil-fuel based technologies that can capture and sequester carbon. Challenges for the expanded global use of nuclear energy include the global capacity for nuclear construction, proliferation, uranium availability, and waste disposal. While the economic costs of nuclear fuel and power are important, non-economic issues transcend the issues of costs. In this regard, advanced nuclear technologies and new vision for the global use of nuclear energy are important considerations for the future of nuclear power and climate change.
Dynamical symmetries of the shell model
Energy Technology Data Exchange (ETDEWEB)
Van Isacker, P
2000-07-01
The applications of spectrum generating algebras and of dynamical symmetries in the nuclear shell model are many and varied. They stretch back to Wigner's early work on the supermultiplet model and encompass important landmarks in our understanding of the structure of the atomic nucleus such as Racah's SU(2) pairing model and Elliot's SU(3) rotational model. One of the aims of this contribution has been to show the historical importance of the idea of dynamical symmetry in nuclear physics. Another has been to indicate that, in spite of being old, this idea continues to inspire developments that are at the forefront of today's research in nuclear physics. It has been argued in this contribution that the main driving features of nuclear structure can be represented algebraically but at the same time the limitations of the symmetry approach must be recognised. It should be clear that such approach can only account for gross properties and that any detailed description requires more involved numerical calculations of which we have seen many fine examples during this symposium. In this way symmetry techniques can be used as an appropriate starting point for detailed calculations. A noteworthy example of this approach is the pseudo-SU(3) model which starting from its initial symmetry Ansatz has grown into an adequate and powerful description of the nucleus in terms of a truncated shell model. (author)
Symmetry and symmetry breaking in quantum mechanics
International Nuclear Information System (INIS)
Chomaz, Philippe
1998-01-01
In the world of infinitely small, the world of atoms, nuclei and particles, the quantum mechanics enforces its laws. The discovery of Quanta, this unbelievable castration of the Possible in grains of matter and radiation, in discrete energy levels compels us of thinking the Single to comprehend the Universal. Quantum Numbers, magic Numbers and Numbers sign the wave. The matter is vibration. To describe the music of the world one needs keys, measures, notes, rules and partition: one needs quantum mechanics. The particles reduce themselves not in material points as the scholars of the past centuries thought, but they must be conceived throughout the space, in the accomplishment of shapes of volumes. When Einstein asked himself whether God plays dice, there was no doubt among its contemporaries that if He exists He is a geometer. In a Nature reduced to Geometry, the symmetries assume their role in servicing the Harmony. The symmetries allow ordering the energy levels to make them understandable. They impose there geometrical rules to the matter waves, giving them properties which sometimes astonish us. Hidden symmetries, internal symmetries and newly conceived symmetries have to be adopted subsequently to the observation of some order in this world of Quanta. In turn, the symmetries provide new observables which open new spaces of observation
Macroscopic-microscopic model of nuclear potential energy
Tamagno, Pierre; Bouland, Olivier; Serot, Olivier; Moller, Peter
2017-09-01
To improve the evaluation of nuclear observables, refined models are to be used more and more as underlying analysis tools. Fission is a complex process and is the less accurately described with current models. Standard evaluation models rely on the Hill-Wheeler formalism for the fission transmission coefficient, which in turns is based on phenomenological parameters "reflecting" the fission barrier heights and widths. To reduce the weight of phenomenology in the evaluation process, nuclear structure models are expected to embed more and more microscopic descriptions. As models are rarely exact, evaluators are often compelled to "tune" model parameters so that observables can be properly reproduced. Related computation time can thus be a major hindrance to the use of advanced models in evaluation as final adjustments are expected to remain necessary. For this reason, a macroscopic-microscopic model has been selected to replace the current phenomenological description of fission barriers. The Finite-Range Liquid-Drop Model (FRLDM) has been implemented in the CONRAD evaluation code and its present implementation shows remarkable consistency with experimental and published benchmark data. The CONRAD code can be used to provide expectation values but also related uncertainties and covariance data. Sensitivity of FRLDM parameters and the correlation matrix between these parameters have been obtained so that further uncertainty propagation on barrier heights can be carried out in the near future.
Potential safety-related incidents with possible applicability to a nuclear fuel reprocessing plant
International Nuclear Information System (INIS)
Perkins, W.C.; Durant, W.S.; Dexter, A.H.
1980-12-01
The occurrence of certain potential events in nuclear fuel reprocessing plants could lead to significant consequences involving risk to operating personnel or to the general public. This document is a compilation of such potential initiating events in nuclear fuel reprocessing plants. Possible general incidents and incidents specific to key operations in fuel reprocessing are considered, including possible causes, consequences, and safety features designed to prevent, detect, or mitigate such incidents
Pyrolysis and its potential use in nuclear graphite disposal
International Nuclear Information System (INIS)
Mason, J.B.; Bradbury, D.
2001-01-01
Graphite is used as a moderator material in a number of nuclear reactor designs, such as MAGNOX and AGR gas cooled reactors in the United Kingdom and the RBMK design in Russia. During construction the moderator of the reactor is usually installed as an interlocking structure of graphite bricks. At the end of reactor life the graphite moderator, weighing typically 2,000 tonnes, is a radioactive waste which requires eventual management. Radioactive graphite disposal options conventionally include: In-situ SAFESTORE for extended periods to permit manual disassembly of the graphite moderator through decay of short-lived radionuclides. Robotic or manual disassembly of the reactor core followed by disposal of the graphite blocks. Robotic or manual disassembly of the reactor core followed by incineration of the graphite and release of the resulting carbon dioxide Studsvik, Inc. is a nuclear waste management and waste processing company organised to serve the US nuclear utility and government facilities. Studsvik's management and technical staff have a wealth of experience in processing liquid, slurry and solid low level radioactive waste using (amongst others) pyrolysis and steam reforming techniques. Bradtec is a UK company specialising in decontamination and waste management. This paper describes the use of pyrolysis and steam reforming techniques to gasify graphite leading to a low volume off-gas product. This allows the following options/advantages. Safe release of any stored Wigner energy in the graphite. The process can accept small pieces or a water-slurry of graphite, which enables the graphite to be removed from the reactor core by mechanical machining or water cutting techniques, applied remotely in the reactor fuel channels. In certain situations the process could be used to gasify the reactor moderator in-situ. The low volume of the off-gas product enables non-carbon radioactive impurities to be efficiently separated from the off-gas. The off-gas product can
International Nuclear Information System (INIS)
Mainzer, K.
1988-01-01
Symmetry, disymmetry, chirality etc. are well-known topics in chemistry. But they cannot only be found on the molecular level of matter. Atoms and elementary particles in physics are also characterized by particular symmetry groups. Even living organisms and populations on the macroscopic level have functional properties of symmetry. The whole physical, chemical, and biological evolution seems to be regulated by the emergence of new symmetries and the breaking down of old ones. One is reminded of Heisenberg's famous statement: 'Die letzte Wurzel der Erscheinungen ist also nicht die Materie, sondern das mathematische Gesetz, die Symmetrie, die mathematische Form' (Wandlungen in den Grundlagen der Naturwissenschaften, 1959). Historically the belief in symmetry and simplicity of nature has a long philosophical tradition from the Pythagoreans, Plato and Greek astronomers to Kepler and modern scientists. Today, 'symmetries in nature' is a common topic of mathematics, physics, chemistry, and biology. A lot of Nobel prizes were given in honour of inquiries concerning symmetries in nature. The fascination of symmetries is not only motivated by science, but by art and religion too. Therefore 'symmetris in nature' is an interdisciplinary topic which may help to overcome C.P. Snow's 'Two Cultures' of natural sciences and humanities. (author) 17 refs., 21 figs
The potential role of nuclear power in alleviating the risks of global climate change
International Nuclear Information System (INIS)
Semenov, B.A.; Bennett, L.L.; Bertel, E.; Van de Vate, J.F.
1995-01-01
The potential role of nuclear power in alleviating the risks for global climate change is illustrated by comprehensive comparison of full energy chain analysis of greenhouse gas emissions from alternative electricity generation sources. It is shown that nuclear power is one of the most greenhouse benign energy sources with greenhouse emissions similar to wind and geothermal energy chains, while other renewable chains, including hydropower, emit in the range of 2 to 5 times more greenhouse gases per unit of electricity produced, and fossil fuelled chains, emit some 50 times more. The prospects for nuclear power deployment are analyzed taking into account the barriers and limits to the implementation of nuclear power programmes. Medium term projections of nuclear electricity generation are given and a long term nuclear scenario aiming towards lowering carbon dioxide emissions from the electricity sector is presented and discussed. 4 figs., 1 tab
Holography without translational symmetry
Vegh, David
2013-01-01
We propose massive gravity as a holographic framework for describing a class of strongly interacting quantum field theories with broken translational symmetry. Bulk gravitons are assumed to have a Lorentz-breaking mass term as a substitute for spatial inhomogeneities. This breaks momentum-conservation in the boundary field theory. At finite chemical potential, the gravity duals are charged black holes in asymptotically anti-de Sitter spacetime. The conductivity in these systems generally exhibits a Drude peak that approaches a delta function in the massless gravity limit. Furthermore, the optical conductivity shows an emergent scaling law: $|\\sigma(\\omega)| \\approx {A \\over \\omega^{\\alpha}} + B$. This result is consistent with that found earlier by Horowitz, Santos, and Tong who introduced an explicit inhomogeneous lattice into the system.
Kohn's theorem and Galilean symmetry
Zhang, P.-M.; Horvathy, P. A.
2011-08-01
The relation between the separability of a system of charged particles in a uniform magnetic field and Galilean symmetry is revisited using Duval's “Bargmann framework”. If the charge-to-mass ratios of the particles are identical, ea/ma=ɛ for all particles, then the Bargmann space of the magnetic system is isometric to that of an anisotropic harmonic oscillator. Assuming that the particles interact through a potential which only depends on their relative distances, the system splits into one representing the center of mass plus a decoupled internal part, and can be mapped further into an isolated system using Niederer's transformation. Conversely, the manifest Galilean boost symmetry of the isolated system can be “imported” to the oscillator and to the magnetic systems, respectively, to yield the symmetry used by Gibbons and Pope to prove the separability. For vanishing interaction potential the isolated system is free and our procedure endows all our systems with a hidden Schrödinger symmetry, augmented with independent internal rotations. All these properties follow from the cohomological structure of the Galilei group, as explained by Souriau's “décomposition barycentrique”.
Potential of small nuclear reactors for future clean and safe energy sources
International Nuclear Information System (INIS)
Sekimoto, H.
1992-01-01
To cope with the various kinds of energy demands expected in the 21st century, it is necessary to explore the potential of small nuclear reactors and to find a way of promoting their introduction to society. The main goal of current research activities is 'the constitution of the self-consistent nuclear energy system'. These activities can be understood by realizing that the nuclear community is facing a turning point for its survival in the 21st century. Self-consistency can be manifested by investigating and developing the potential advantages of the nuclear fission reaction and lessening the potential disadvantages. The contributions in this volume discuss concepts of small reactors, applications of small reactors, and consistency with conventional energy supply systems
Nuclear momentum distribution and potential energy surface in hexagonal ice
Lin, Lin; Morrone, Joseph; Car, Roberto; Parrinello, Michele
2011-03-01
The proton momentum distribution in ice Ih has been recently measured by deep inelastic neutron scattering and calculated from open path integral Car-Parrinello simulation. Here we report a detailed investigation of the relation between momentum distribution and potential energy surface based on both experiment and simulation results. The potential experienced by the proton is largely harmonic and characterized by 3 principal frequencies, which can be associated to weighted averages of phonon frequencies via lattice dynamics calculations. This approach also allows us to examine the importance of quantum effects on the dynamics of the oxygen nuclei close to the melting temperature. Finally we quantify the anharmonicity that is present in the potential acting on the protons. This work is supported by NSF and by DOE.
International Nuclear Information System (INIS)
Alhassid, Y.; Leviatan, A.
1993-01-01
A novel symmetry structure, partial dynamical symmetry is introduced. The Hamiltonian is not invariant under the transformations of a group G and irreps of G are mixed in its eigenstates. it possesses, however, a partial set of eigenstates which do have good symmetry and can be labeled by irreps of G. A general algorithm to construct such Hamiltonians for a semi-simple group G is presented. (Author) 6 refs
Potential impacts of nuclear power plant operation on the public
International Nuclear Information System (INIS)
Kotulan, J.
1999-01-01
Findings from the examination of the health status of population living in the vicinity of nuclear facilities abroad (England, France, Germany ...) are summarized. Where a significant increase in the incidence of leukemia in children and non-Hodgkin's lymphomas were observed, these are not attributed to radioactivity; rather, the virus theory seems to account best for this phenomenon. Author's findings in the area of the Dukovany NPP in the Czech Republic (which have been published) are summarized as follows: (i) Total mortality 1986-1994 in the vicinity of the plant is the same as or lower than in reference regions; (ii) This also applies to premature deaths and to the 'lost years' indicator; (iii) Death rate due to tumors is significantly lower than in reference regions; (iv) This also applies to the majority of the individual types of tumors; (v) Leukemia seems to be an exception, its incidence being higher than in reference regions. The absolute figures, however, are low (11 + 17 in the exposed region) and the differences are not statistically significant. This also applies to lymphatic tissue tumors. (7) Mental well-being was no different from the reference region; in some respects, surprisingly enough, it even appeared to be more favourable. (P.A.)
Synthesis and evaluation of potential ligands for nuclear waste processing
Iqbal, M.
2012-01-01
The research presented in this thesis deals with the synthesis and evaluation of new potential ligands for the complexation of actinide and lanthanide ions either for their extraction from bulk radioactive waste or their stripping from an extracted organic phase for final processing of the waste. In
Optical metamaterials with quasicrystalline symmetry: symmetry-induced optical isotropy
International Nuclear Information System (INIS)
Kruk, S.S.; Decker, M.; Helgert, Ch.; Neshev, D.N.; Kivshar, Y.S.; Staude, I.; Powell, D.A.; Pertsch, Th.; Menzel, Ch.; Helgert, Ch.; Etrich, Ch.; Rockstuhl, C.; Menzel, Ch.
2013-01-01
Taking advantage of symmetry considerations, we have analyzed the potential of various metamaterials to affect the polarization state of light upon oblique illumination. We have shown that depending on the angle of illumination, metamaterials are able to support specific polarization states. The presented methodology that using ellipticity and circular dichroism, provides an unambiguous language for discussing the impact of the inherent symmetry of the metamaterial lattices on their far-field response. Our findings allow the quantification analysis of the impact of inter-element coupling and lattice symmetry on the optical properties of metamaterials, and to separate this contribution from the response associated with a single meta-atom. In addition, we have studied the concept of optical quasicrystalline metamaterials, revealing that the absence of translational symmetry (periodicity) of quasicrystalline metamaterials causes an isotropic optical response, while the long-range positional order preserves the resonance properties. Our findings constitute an important step towards the design of optically isotropic metamaterials and metasurfaces. (authors)
Symmetries in heavy nuclei and the proton-neutron interaction
Energy Technology Data Exchange (ETDEWEB)
Casten, R.F.
1986-01-01
The Interacting Boson Approximation (IBA) nuclear structure model can be expressed in terms of the U(6) group, and thereby leads to three dynamical symmetries (or group chains) corresponding to different nuclear coupling schemes and geometrical shapes. The status of the empirical evidence for these three symmetries is reviewed, along with brief comments on the possible existence of supersymmetries in nuclei. The relationships between these symmetries, the nuclear phase transitional regions linking them, and the residual proton-neutron interaction are discussed in terms of a particularly simple scheme for parameterizing the effects of that interaction. 34 refs., 15 figs.
On the Potential of MAX phases for Nuclear Applications
Tallman, Darin Joseph
Materials within nuclear reactors experience some of the harshest environments currently known to man, including long term operation in extreme temperatures, corrosive media, and fast neutron fluences with up to 100 displacements per atom, dpa. In order to improve the efficiency and safety of current and future reactors, new materials are required to meet these harsh demands. The M n+1AXn phases, a growing family of ternary nano-layered ceramics, possess a desirable combination of metallic and ceramic properties. They are composed of an early transition metal (M), a group 13--16 element (A), and carbon and/or nitrogen (X). The MAX phases are being proposed for use in such extreme environments because of their unique combination of high fracture toughness values and thermal conductivities, machinability, oxidation resistance, and ion irradiation damage tolerance. Previous ion irradiation studies have shown that Ti3SiC2 and Ti3AlC2 resist irradiation damage, maintaining crystallinity up to 50 dpa. The aim of this work was to explore the effect of neutron irradiation, up to 9 dpa and at temperatures of 100 to 1000 °C, on select MAX phases for the first time. The MAX phases Ti3SiC2, Ti 3AlC2, Ti2AlC, and Ti2AlN were synthesized, and irradiated in test reactors that simulate in-pile conditions of nuclear reactors. X-ray diffraction, XRD, pattern refinements of samples revealed a distortion of the crystal lattice after low temperature irradiation, which was not observed after high temperature irradiations. Additionally, the XRD results indicated that Ti3AlC2 and Ti2AlN dissociated after relatively low neutron doses. This led us to focus on Ti 3SiC2 and Ti2AlC. For the first time, dislocation loops were observed in Ti3SiC 2 and Ti2AlC as a result of neutron irradiation. At 1 x 1023 loops/m3, the loop density in Ti2 AlC after irradiation to 0.1 dpa at 700°C was 1.5 orders of magnitude greater than that observed in Ti3SiC2, at 3 x 1021 loops/m3. The Ti2AlC composition
Hexagonal response matrix using symmetries
International Nuclear Information System (INIS)
Gotoh, Y.
1991-01-01
A response matrix for use in core calculations for nuclear reactors with hexagonal fuel assemblies is presented. It is based on the incoming currents averaged over the half-surface of a hexagonal node by applying symmetry theory. The boundary conditions of the incoming currents on the half-surface of the node are expressed by a complete set of orthogonal vectors which are constructed from symmetrized functions. The expansion coefficients of the functions are determined by the boundary conditions of incoming currents. (author)
Determining the potential volume of industrial process steam to be generated in nuclear facilities
International Nuclear Information System (INIS)
Jobsky, T.
1990-01-01
The present study serves to determine the market potential of nuclear energy for industrial process steam supply according to branches and sites in the Federal Republic of Germany (excluding the new East German Laender). On the nuclear plant side two HTR reference plants with different unit powers of 200 MWth (HTR-Modul) and 100 MWth are investigated. An essential result in analysing the nuclear market potential is the finding that the number of potential users and sites will triple if smaller unit sizes were introduced. This corresponds to an increase in nuclear plant potential from 28 units of 200 MWth each to 91 units of 100 MWth on the assumptions made in this study. A comparison of economic efficiency between fossil-fired power production plants and the HTR-Modul shows the competitiveness of nuclear process steam and electricity production in the base load range. A single-site evaluation for the centres of energy demand competes conceptually with a combined heat supply by nuclear long-distance energy. This integrated supply concept makes it possible to supply considerably more industrial companies with process steam while reducing the number of sites, since the heat requirements of smaller sites can also be covered by the integrated system. (orig.) [de
Showstack, Randy
With spent nuclear fuel piling up at power plants around the United States, and with a potential permanent nuclear waste repository at Nevada's Yucca Mountain not scheduled to accept waste until 11 years from now in the year 2010, the nuclear energy industry and many members of Congress have renewed their push to establish an interim repository at the adjacent Nevada Test Site of nuclear bombs.At a sometimes contentious March 12 hearing to consider the Nuclear Waste Policy Act of 1999 (House Resolution 45) that would require an interim facility to begin accepting waste in 2003, bill cosponsor Rep. Jim Barton (R-Tex.) told Energy Secretary Bill Richardson that he preferred that Congress and the Clinton Administration negotiate rather than fight over the measure.
Energy Technology Data Exchange (ETDEWEB)
Hoffman, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2013-09-06
We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for targets ranging from Terbium (Z = 65) to Rhenium (Z = 75). Of particular interest are the cross sections on Tm, Lu, and Ta including reactions on isomeric targets.
Classical properties and semiclassical calculations in a spherical nuclear average potential
International Nuclear Information System (INIS)
Carbonell, J.; Brut, F.; Arvieu, R.; Touchard, J.
1984-03-01
We study the relation between the classical properties or an average nuclear potential and its spectral properties. We have drawn the energy-action surface of this potential and related its properties to the spectral ones in the framework of the EBK semiclassical method. We also describe a method allowing us to get the evolution of the spectrum with the mass number
Marchis, Iuliana
2009-01-01
Symmetry is one of the fundamental concepts in Geometry. It is a Mathematical concept, which can be very well connected with Art and Ethnography. The aim of the article is to show how to link the geometrical concept symmetry with interculturality. For this mosaics from different countries are used.
Quantum symmetry for pedestrians
International Nuclear Information System (INIS)
Mack, G.; Schomerus, V.
1992-03-01
Symmetries more general than groups are possible in quantum therory. Quantum symmetries in the narrow sense are compatible with braid statistics. They are theoretically consistent much as supersymmetry is, and they could lead to degenerate multiplets of excitations with fractional spin in thin films. (orig.)
Schaft, A.J. van der
1987-01-01
It is argued that the existence of symmetries may simplify, as in classical mechanics, the solution of optimal control problems. A procedure for obtaining symmetries for the optimal Hamiltonian resulting from the Maximum Principle is given; this avoids the actual calculation of the optimal
2016-01-01
The Symmetry Festival is a science and art program series, the most important periodic event (see its history) to bring together scientists, artists, educators and practitioners interested in symmetry (its roots, what is behind, applications, etc.), or in the consequences of its absence.
Charged fluids with symmetries
Indian Academy of Sciences (India)
metric tensor field and generate constants of the motion along null geodesics for massless particles. Conformal symmetries arise in various physical applications. The existence of conformal symmetries in relativistic cosmological models, with restrictions on the matter content and fluid four-velocity, have been extensively ...
Vendors woo South Africa as a potential new 'powerhouse' for nuclear
Energy Technology Data Exchange (ETDEWEB)
Shepherd, John [nuclear24, London (United Kingdom)
2014-04-15
South Africa is a country which is increasingly seen as a potential new nuclear market that promises to give one or more of the world's major nuclear vendors an important foothold on the continent. South Africa has two pressurised water reactors operating at the Koeberg nuclear plant. The 930-megawatt (MW) first unit entered commercial operation in July 1984, followed by the second (900 MW) unit in November 1985. These are the only commercial nuclear power plants on the continent of Africa. South Africa's updated draft integrated resources plan (IRP) for electricity for 2010-30, for which a public consultation period ended in February of this year, included revised projections. that suggested no new nuclear baseload capacity would be needed 'until after 2025'. A capacity 'at least 6,600 MW less' is required in terms of reliable overall generating capacity in 2030. However great South Africa's demand for a clean, affordable and reliable supply of nuclear-generated electricity, coupled with the economic benefits such developments will bring, investors also understand the potential for nuclear growth in this part of the world. (orig.)
Symmetry energy in the liquid–gas mixture
Energy Technology Data Exchange (ETDEWEB)
López, J.A., E-mail: jorgelopez@utep.edu [University of Texas at El Paso, El Paso, TX 79968 (United States); Terrazas Porras, S. [Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua (Mexico)
2017-01-15
Results from classical molecular dynamics simulations of infinite nuclear systems with varying density, temperature and isospin content are used to calculate the symmetry energy at low densities. The results show an excellent agreement with the experimental data and corroborate the claim that the formation of clusters has a strong influence on the symmetry energy in the liquid–gas coexistence region.
Symmetry remnants in the face of competing interactions in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A., E-mail: ami@phys.huji.ac.il [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Macek, M., E-mail: michal.macek@yale.edu [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT 06520-8120 (United States)
2015-10-15
Detailed description of nuclei necessitates model Hamiltonians which break most dynamical symmetries. Nevertheless, generalized notions of partial and quasi dynamical symmetries may still be applicable to selected subsets of states, amidst a complicated environment of other states. We examine such scenarios in the context of nuclear shape-phase transitions.
Symmetry remnants in the face of competing interactions in nuclei
International Nuclear Information System (INIS)
Leviatan, A.; Macek, M.
2015-01-01
Detailed description of nuclei necessitates model Hamiltonians which break most dynamical symmetries. Nevertheless, generalized notions of partial and quasi dynamical symmetries may still be applicable to selected subsets of states, amidst a complicated environment of other states. We examine such scenarios in the context of nuclear shape-phase transitions
Involution symmetries and the PMNS matrix
Indian Academy of Sciences (India)
Palash B Pal
2017-10-09
Oct 9, 2017 ... 1Saha Institute of Nuclear Physics, Block-AF, Sector-1, Bidhan Nagar, Kolkata 700 064, India. 2Indian Association for the Cultivation of Science, 2A & 2B Raja S.C. Mullick ... paper [3] we take the third assumption in addition, and try to find symmetries consistent with this extra one. The purpose of this talk is ...
Configuration-mixed effective SU(3) symmetries
Hess, P O; Hunyadi, M; Kvi, A G; Cseh, J
2002-01-01
The procedure of Jarrio et al. (Nucl. Phys. A 528, 409 (1991)) for the determination of the effective SU(3) symmetry of nuclear states is extended to small deformations and to oblate nuclei. Self-consistency checks are carried out both for light and for heavy nuclei. (orig.)
Potential National Security Applications of Nuclear Resonance Fluorescence Methods
International Nuclear Information System (INIS)
Warren, Glen A.; Peplowski, Patrick N.; Caggiano, Joseph A.
2009-01-01
The objective of this report is to document the initial investigation into the possible research issues related to the development of NRF-based national security applications. The report discusses several potential applications ranging from measuring uranium enrichment in UF6 canisters to characterization of gas samples. While these applications are varied, there are only a few research issues that need to be addressed to understand the limitation of NRF in solving these problems. These research issues range from source and detector development to measuring small samples. The next effort is to determine how best to answer the research issues, followed by a prioritization of those questions to ensure that the most important are addressed. These issues will be addressed through either analytical calculations, computer simulations, analysis of previous data or collection of new measurements. It will also be beneficial to conduct a thorough examination of a couple of the more promising applications in order to develop concrete examples of how NRF may be applied in specific situations. The goals are to develop an understanding of whether the application of NRF is limited by technology or physics in addressing national security applications, to gain a motivation to explore those possible applications, and to develop a research roadmap so that those possibilities may be made reality.
Takahashi, Y.; Eby, P. B.
1985-01-01
Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.
The zonal satellite problem. III Symmetries
Directory of Open Access Journals (Sweden)
Mioc V.
2002-01-01
Full Text Available The two-body problem associated with a force field described by a potential of the form U =Sum(k=1,n ak/rk (r = distance between particles, ak = real parameters is resumed from the only standpoint of symmetries. Such symmetries, expressed in Hamiltonian coordinates, or in standard polar coordinates, are recovered for McGehee-type coordinates of both collision-blow-up and infinity-blow-up kind. They form diffeomorphic commutative groups endowed with a Boolean structure. Expressed in Levi-Civita’s coordinates, the problem exhibits a larger group of symmetries, also commutative and presenting a Boolean structure.
International Nuclear Information System (INIS)
ElBaradei, M.
2004-01-01
Today, the focus of the world is on nuclear proliferation and the potential threat of nuclear terrorism in Asia and the Pacific, and this address is presenting the perspectives on the challenges IAEA faces, and how the IAEA is working to strengthen nuclear security and the nuclear non-proliferation regime. But one would emphasize at the outset that, while much of our work must begin locally and regionally, we must not forget to think globally, because ultimately the existence of a nuclear threat anywhere is a threat everywhere, and as a global community, we will win or lose this battle together. This presentation, discusses cooperation, assistance, regional and international networks, and the importance of learning from each other. In effect, the focal subject is 'security culture', a mindset that, while providing the impetus for local and regional action, thinks globally and is fully capable of extending across borders. Sixty years ago, on a day in August, the dawn of the Nuclear Age in Asia left nearly a quarter of a million people dead, with two devices considered crude by modern standards. For six decades, we have managed to avoid a repeat of that event, but remain haunted by the prospect. It is my firm belief that we cannot move out from under the shadow of Hiroshima and Nagasaki until we are ready to make that move collectively, and build a system of security that transcends borders, that focuses on the equal value of every human life, and in which nuclear weapons have no place. May it not ultimately be said of our civilization that we created the inventions that led to our own demise
Löschberger, A.; Van de Linde, S.; Debauvalle, M.C.; Rieger, B.; Heilemann, M.; Krohne, G.; Sauer, M.
2012-01-01
One of the most complex molecular machines of cells is the nuclear pore complex (NPC), which controls all trafficking of molecules in and out of the nucleus. Because of their importance for cellular processes such as gene expression and cytoskeleton organization, the structure of NPCs has been
International Nuclear Information System (INIS)
Chang, Y.I.; Till, C.E.; Rudolph, R.R.; Deen, J.R.; King, M.J.
1977-09-01
The fuel utilization characteristics for LWR, SSCR, CANDU and LMFBR reactor concepts are quantified for various fuel cycle options, including once-through cycles, thorium cycles, and denatured cycles. The implications of various alternative reactor deployment strategies on the long-term nuclear power growth potential are then quantified in terms of the maximum nuclear capacity that can be achieved and the growth pattern over time, subject to the constraint of a fixed uranium-resource base. The overall objective of this study is to shed light on any large differences in the long-term potential that exist between various alternative reactor/fuel cycle deployment strategies
A way forward in the study of the symmetry energy: experiment, theory, and observation
Energy Technology Data Exchange (ETDEWEB)
Horowitz, Charles; Brown, E F.; Kim, Y; Lynch, W G.; Michaels, Robert; Ono, A; Piekarewicz, Jorge; Tsang, M B.; Wolter, H H.
2014-07-01
The symmetry energy describes how the energy of nuclear matter rises as one goes away from equal numbers of neutrons and protons. This is very important to describe neutron rich matter in astrophysics. This article reviews our knowledge of the symmetry energy from theoretical calculations, nuclear structure measurements, heavy ion collisions, and astronomical observations. We then present a roadmap to make progress in areas of relevance to the symmetry energy that promotes collaboration between astrophysics and the nuclear physics communities.
Africa's developing nuclear landscape holds potential for investors
Energy Technology Data Exchange (ETDEWEB)
Shepherd, John [nuclear 24, Brighton (United Kingdom)
2015-08-15
Africa is continuing to draw interest from potential nuclear investors as more of the region's nations consider the prospects for launching civil nuclear programmes. Much of the interest has been driven by South Africa, which announced its intention to push ahead with building a new fleet of nuclear power plants more than two years ago. South Africa's Department of Energy said it aims to select a ''strategic partner or partners'' for its planned new nuclear programme by the end of fiscal year 2015. The country's existing twin-unit Koeberg is the African continent's sole nuclear power plant, but expectations are high that this will change. According to 'The World Nuclear Supply Chain: Outlook 2030', released at the start of this year by the World Nuclear Association, Africa and Latin America could see investments of $ 20 billion (Euro 18.2 bn) and $ 14 billion, respectively over the next 15 years.
Schwichtenberg, Jakob
2015-01-01
This is a textbook that derives the fundamental theories of physics from symmetry. It starts by introducing, in a completely self-contained way, all mathematical tools needed to use symmetry ideas in physics. Thereafter, these tools are put into action and by using symmetry constraints, the fundamental equations of Quantum Mechanics, Quantum Field Theory, Electromagnetism, and Classical Mechanics are derived. As a result, the reader is able to understand the basic assumptions behind, and the connections between the modern theories of physics. The book concludes with first applications of the previously derived equations.
DEFF Research Database (Denmark)
Avery, John Scales; Rettrup, Sten; Avery, James Emil
In theoretical physics, theoretical chemistry and engineering, one often wishes to solve partial differential equations subject to a set of boundary conditions. This gives rise to eigenvalue problems of which some solutions may be very difficult to find. For example, the problem of finding...... in such problems can be much reduced by making use of symmetry-adapted basis functions. The conventional method for generating symmetry-adapted basis sets is through the application of group theory, but this can be difficult. This book describes an easier method for generating symmetry-adapted basis sets...
Wei, Gao-Feng; Li, Bao-An; Yong, Gao-Chan; Ou, Li; Cao, Xin-Wei; Liu, Xu-Yang
2018-03-01
Within the isospin- and momentum-dependent transport model IBUU11, we examine the relativistic retardation effects of electrical fields on the π-/π+ ratio and neutron-proton differential transverse flow in heavy-ion collisions at intermediate energies. Compared to the static Coulomb fields, the retarded electric fields of fast-moving charges are known to be anisotropic and the associated relativistic corrections can be significant. They are found to increase the number of energetic protons in the participant region at the maximum compression by as much as 25% but that of energetic neutrons by less than 10% in 197Au+197Au reactions at a beam energy of 400 MeV/nucleon. Consequently, more π+ and relatively fewer π- mesons are produced, leading to an appreciable reduction of the π-/π+ ratio compared to calculations with the static Coulomb fields. Also, the neutron-proton differential transverse flow, as another sensitive probe of high-density symmetry energy, is also decreased appreciably due to the stronger retarded electrical fields in directions perpendicular to the velocities of fast-moving charges compared to calculations using the isotropic static electrical fields. Moreover, the retardation effects on these observables are found to be approximately independent of the reaction impact parameter.
International Nuclear Information System (INIS)
Han Baohua; Li Jianguo; Ma Binghui; Zhang Yue; Sun Qunli; Hu Yuping
2012-01-01
This study is based on the hydrological data near Chongqing Fuling Nuclear Power Plant along the Yangtze River, the present situation of the ecological environment of the Three Gorges Reservoir and the predicted results of thermal effluents from Chongqing Fuling Nuclear Power Plant. The standards of cooling water and the thermal tolerances indexes of aquatic organisms were investigated. The effects of thermal effluents on aquatic organisms were analyzed. The potential impact of Chongqing Fuling nuclear power plant to the Three Gorges Reservoir was explained. The results show that in the most adverse working conditions, the surface temperature near the outfall area is not more than 1℃, the temperature of thermal effluents do not exceed the suitable thermal range of fish breeding, growth and other thermal tolerances indexes. Thermal effluents from nuclear power plant have no influence about fish, plankton and benthic organisms in the Three Gorges Reservoir. (authors)
International Nuclear Information System (INIS)
DeSteese, J.G.; Rhoads, R.E.
1978-01-01
This review presents the results of issue analysis used to identify potential problems which may impact the transportation of nuclear fuel cycle materials between now and 2000. An objective of this effort is to provide advanced warning of potential problems which may inhibit the future development of safe and environmentally acceptable nuclear material transportation systems. Issue analysis was also used to establish the priorities of potential problems. This provides a basis for recommending research, development and other necessary action to address the potentially adverse effects of these problems. Over 100 problem issues were identified in workshop sessions and represent the combined opinions of transportation experts in industry, government and research institutions. A panel ranked potential impact and immediacy of the problem issues on a scale of 1 to 5. The product of the impact and immediacy ranking was taken to indicate relative importance. The type of potential problem identified as most important has consequences which may impose unnecessarily severe or costly restrictions on nuclear material transportation. Ten specific high priority potential problems are discussed which collectively may result in a future inadequacy of transportation for spent fuel and waste materials. These problems may become critical in the next decade. Recommendations are made for new effort that addresses the solution of these problems. A brief review is included of some potential problems judged to be currently of low priority, but which may become more significant toward the end of the century
REVIEW OF THE POTENTIAL OF NUCLEAR HYDROGEN FOR ADDRESSING ENERGY SECURITY AND CLIMATE CHANGE
Energy Technology Data Exchange (ETDEWEB)
James E. O' Brien
2010-06-01
Nuclear energy has the potential to exert a major positive impact on energy security and climate change by coupling it to the transportation sector, primarily through hydrogen production. In the short term, this coupling will provide carbon-free hydrogen for upgrading increasingly lower quality petroleum resources such as oil sands, offsetting carbon emissions associated with steam methane reforming. In the intermediate term, nuclear hydrogen will be needed for large-scale production of infrastructure-compatible synthetic liquid fuels. In the long term, there is great potential for the use of hydrogen as a direct vehicle fuel, most likely in the form of light-duty pluggable hybrid hydrogen fuel cell vehicles. This paper presents a review of the potential benefits of large-scale nuclear hydrogen production for energy security (i.e. displacing imported petroleum) and reduction of greenhouse gas emissions. Lifecycle benefits of nuclear energy in this context are presented, with reference to recent major publications on this topic. The status of US and international nuclear hydrogen research programs are discussed. Industry progress toward consumer-grade hydrogen fuel cell vehicles are also be examined.
Relabeling symmetries in hydrodynamics and magnetohydrodynamics
International Nuclear Information System (INIS)
Padhye, N.; Morrison, P.J.
1996-04-01
Lagrangian symmetries and concomitant generalized Bianchi identities associated with the relabeling of fluid elements are found for hydrodynamics and magnetohydrodynamics (MHD). In hydrodynamics relabeling results in Ertel's theorem of conservation of potential vorticity, while in MHD it yields the conservation of cross helicity. The symmetries of the reduction from Lagrangian (material) to Eulerian variables are used to construct the Casimir invariants of the Hamiltonian formalism
Antinucleon spectra in the Dirac equation with scalar and vector Wood-Saxon potentials
International Nuclear Information System (INIS)
Lisboa, R.; Malheiro, M.; Alberto, P.; Castro, A. S. de
2009-01-01
We analyze here the spin and pseudospin symmetry for the antinucleon spectra solving the Dirac equation with scalar and vector Wood-Saxon potentials. In relativistic nuclear mean field theories where these potentials have large magnitudes and opposite signs we show that contrary to the nucleon case where pseudospin interaction is never very small and cannot be treated perturbatively, for antinucleon systems this interaction is perturbative and an exact pseudospin symmetry is possible. This result manifests the relativistic nature of the nuclear pseudospin symmetry.
Neutron matter, symmetry energy and neutron stars
Energy Technology Data Exchange (ETDEWEB)
Stefano, Gandolfi [Los Alamos National Laboratory (LANL); Steiner, Andrew W [ORNL
2016-01-01
Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.
Gauge symmetry from decoupling
Directory of Open Access Journals (Sweden)
C. Wetterich
2017-02-01
Full Text Available Gauge symmetries emerge from a redundant description of the effective action for light degrees of freedom after the decoupling of heavy modes. This redundant description avoids the use of explicit constraints in configuration space. For non-linear constraints the gauge symmetries are non-linear. In a quantum field theory setting the gauge symmetries are local and can describe Yang–Mills theories or quantum gravity. We formulate gauge invariant fields that correspond to the non-linear light degrees of freedom. In the context of functional renormalization gauge symmetries can emerge if the flow generates or preserves large mass-like terms for the heavy degrees of freedom. They correspond to a particular form of gauge fixing terms in quantum field theories.
Wigner's Symmetry Representation Theorem
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 10. Wigner's Symmetry Representation Theorem: At the Heart of Quantum Field Theory! Aritra Kr Mukhopadhyay. General Article Volume 19 Issue 10 October 2014 pp 900-916 ...
Frameworks with crystallographic symmetry.
Borcea, Ciprian S; Streinu, Ileana
2014-02-13
Periodic frameworks with crystallographic symmetry are investigated from the perspective of a general deformation theory of periodic bar-and-joint structures in Euclidean spaces of arbitrary dimension. It is shown that natural parametrizations provide affine section descriptions for families of frameworks with a specified graph and symmetry. A simple geometrical setting for displacive phase transitions is obtained. Upper bounds are derived for the number of realizations of minimally rigid periodic graphs.
Interactions between constituent single symmetries in multiple symmetry
Treder, M.S.; Vloed, G. van der; Helm, P.A. van der
2011-01-01
As a rule, the discriminability of multiple symmetries from random patterns increases with the number of symmetry axes, but this number does not seem to be the only determinant. In particular, multiple symmetries with orthogonal axes seem better discriminable than multiple symmetries with
Nuclear interaction potential in a folded-Yukawa model with diffuse densities
International Nuclear Information System (INIS)
Randrup, J.
1975-09-01
The folded-Yukawa model for the nuclear interaction potential is generalized to diffuse density distributions which are generated by folding a Yukawa function into sharp generating distributions. The effect of a finite density diffuseness or of a finite interaction range is studied. The Proximity Formula corresponding to the generalized model is derived and numerical comparison is made with the exact results. (8 figures)
Symmetry energy of the nucleus in the relativistic Thomas–Fermi ...
Indian Academy of Sciences (India)
S HADDAD
2017-10-26
Oct 26, 2017 ... GANIL/France, and the GSI facility FAIR in Germany, which produce new data for neutron-rich nuclei. A key point is the ... the value of the nuclear matter symmetry energy is deter- mined at the local density value inside the nucleus. The symmetry energy integral and the symmetry energy of the nucleus are ...
The potential of nuclear energy to generate clean electric power in Brazil
International Nuclear Information System (INIS)
Stecher, Luiza C.; Sabundjian, Gaiane; Menzel, Francine; Giarola, Rodrigo S.; Coelho, Talita S.
2013-01-01
The generation of electricity in Brazil is concentrated in hydroelectric generation, renewable and clean source, but that does not satisfy all the demand and leads to necessity of a supplementary thermal sources portion. Considering the predictions of increase in demand for electricity in the next years, it becomes necessary to insert new sources to complement the production taking into account both the volume being produced and the needs of environmental preservation. Thus, nuclear power can be considered a potential supplementary source for electricity generation in Brazil as well as the country has large reserves of fissile material, the generation emits no greenhouse gases, the country has technological mastery of the fuel cycle and it enables the production of large volumes of clean energy. The objective of this study is to demonstrate the potential of nuclear energy in electricity production in Brazil cleanly and safely, ensuring the supplies necessary to maintain the country's economic growth and the increased demand sustainable. For this, will be made an analysis of economic and social indicators of the characteristics of our energy matrix and the availability of our sources, as well as a description of the nuclear source and arguments that justify a higher share of nuclear energy in the matrix of the country. Then, after these analysis, will notice that the generation of electricity from nuclear source has all the conditions to supplement safely and clean supply of electricity in Brazil. (author)
Nuclear power in Europe today and its potential competitive role for tomorrow
International Nuclear Information System (INIS)
Hartmut, B.
1996-01-01
Nuclear power is nowadays one of the cornerstones of the occidental Europe electricity supply system. The electricity European market liberalization as well as the uncertainties resulting from acceptabilities problems (which are due to political risks) represent nevertheless a great challenge for the future use of nuclear power. Concerning the energy consumption, the financial advantage of new nuclear power plants compared with fossil-fired power plants seems to be still possible in the future, but all investment decision should however consider in addition to these less high costs the political financial costs which are difficult to appreciate in a lot of European countries. On account of the current conditions, it would be practically senseless to build new nuclear power plants in these countries. The investment safety required for the construction of new plants is only given unfortunately in a few countries, in France for instance. Without any political conditions modification, new nuclear power plants setting up in most of the occidental European countries will be in a near future probably exceptional and with risks division. However, we must not forget that the nuclear power disposes of the potential which allows to reach objectives of a capital importance on the social plan as for instance the CO 2 decrease, the resources economy, the electric power price stability and the employment protection. In the future, the electric power plants will not be in measure to reach the objectives which have been theirs until now as those will induce disadvantages for competitiveness. After the liberalization, it is then the duty of the political responsible persons to establish a sufficient legal protection for the future use of nuclear power and to create thus the ecological and economical potential bound to these ones. (O.M.)
Human performance improvement in organizations: Potential application for the nuclear industry
International Nuclear Information System (INIS)
2005-11-01
This publication is primarily intended for managers and specialists in nuclear facility operating organizations working in the area of human performance improvement. It is intended to provide them with practical information they can use to improve human performance in their organizations. While some of the information provided in this publication is based upon the experience of nuclear facility operating organizations, most of it comes from human performance improvement initiatives in non-nuclear organizations and industries. The nuclear industry has a long tradition of sharing good management practices in order to foster continuous improvement. However, it is not always realized that many of the practices that are now well established initially came from non-nuclear industries and were subsequently adapted for application to nuclear power plant operating organizations. There is, therefore, good reason to periodically review non-nuclear industry practices for ideas that might have direct or indirect application to the nuclear industry in order to potentially gain benefits such as the following: new approaches to certain problem areas, insights into new or impending challenges, improvements in existing practices, benchmarking of opportunities, development of learning organizations and avoidance of collective blind spots. The preparation of this report was an activity of the project on Effective Training to Achieve Excellence in the Performance of NPP Personnel. The objective of this project is to enhance the capability of Member States to utilize proven practices developed and transferred by the IAEA for improving personnel performance. The expected outcome from this project is the increased use by organizations in Members States of proven engineering and management practices and methodologies developed and transferred by the IAEA to improve personnel performance
Dark matter and global symmetries
Directory of Open Access Journals (Sweden)
Yann Mambrini
2016-09-01
Full Text Available General considerations in general relativity and quantum mechanics are known to potentially rule out continuous global symmetries in the context of any consistent theory of quantum gravity. Assuming the validity of such considerations, we derive stringent bounds from gamma-ray, X-ray, cosmic-ray, neutrino, and CMB data on models that invoke global symmetries to stabilize the dark matter particle. We compute up-to-date, robust model-independent limits on the dark matter lifetime for a variety of Planck-scale suppressed dimension-five effective operators. We then specialize our analysis and apply our bounds to specific models including the Two-Higgs-Doublet, Left–Right, Singlet Fermionic, Zee–Babu, 3-3-1 and Radiative See-Saw models. Assuming that (i global symmetries are broken at the Planck scale, that (ii the non-renormalizable operators mediating dark matter decay have O(1 couplings, that (iii the dark matter is a singlet field, and that (iv the dark matter density distribution is well described by a NFW profile, we are able to rule out fermionic, vector, and scalar dark matter candidates across a broad mass range (keV–TeV, including the WIMP regime.
Integrable systems and lie symmetries in classical mechanics
International Nuclear Information System (INIS)
Sen, T.
1986-01-01
The interrelationship between integrability and symmetries in classical mechanics is studied. Two-dimensional time- and velocity-independent potentials form the domain of the study. It is shown that, contrary to folklore, existence of a single finite symmetry does not ensure integrability. A method due to Darboux is used to construct potentials that admit a time-independent invariant. All potentials admitting invariants linear or quadratic in the momentum coordinates are constructed. These are the only integrable potentials which can be expressed as arbitrary functions of certain arguments. A complete construction of potentials admitting higher-order invariants does not seem possible. However, the necessary general forms for potentials that admit a particular invariant of arbitrary order are found. These invariants must be spherically symmetric in the leading terms. Two kinds of symmetries are studied: point Lie symmetries of the Newtonian equations of motion for conservative potentials, and point Noether symmetries of the action functionals obtained from the standard Lagrangians associated with these potentials. All conservative potentials which admit these symmetries are constructed. The class of potentials admitting Noether symmetries is shown to be a subclass of those admitting Lie symmetries
Coal and nuclear wastes: both potential contributors to environmental and health problems
International Nuclear Information System (INIS)
1981-01-01
The Chairman, Subcommittee on Energy Conservation and Power, House Committee on Energy and Commerce, asked GAO to answer eight questions regarding waste produced by coal and nuclear fuels during the generation of electricity. This report primarily discusses the first two items in the Chairman's request: what are the types and quantities of wastes generated at each step of the coal and nuclear fuel cycles. What are the health and environmental problems associated with these wastes. Based on a comprehensive literature search GAO found that wastes produced by both the coal and nuclear fuel cycles present the potential for significant environmental and health hazards. Because the waste types present different types of hazards, however, it is not possible to determine if either waste type is more of a hazard than the other. Nonetheless, most of the hazards from both fuel cycles can be lessened, or in some cases eliminated, if properly controlled and regulated
Deuteron nuclear interaction potential with heavy nuclei in single folding model
Directory of Open Access Journals (Sweden)
O. V. Babak
2013-09-01
Full Text Available Deuteron interaction potential with heavy nuclei at sub-barrier energies has been constructed in the frame-work of single folding model using the complex dynamic polarization potential. It is shown that the account of finite deuteron size leads to significant increasing of nuclear potential in outer region of interaction. Cross sec-tions of deuteron elastic scattering on 208Pb at energy 7, 7.3 and 8 MeV were calculated and compared with ex-periment data. Calculations were performed without any variations of parameters.
Quantum Space-Time Deformed Symmetries Versus Broken Symmetries
Amelino-Camelia, G
2002-01-01
Several recent studies have concerned the faith of classical symmetries in quantum space-time. In particular, it appears likely that quantum (discretized, noncommutative,...) versions of Minkowski space-time would not enjoy the classical Lorentz symmetries. I compare two interesting cases: the case in which the classical symmetries are "broken", i.e. at the quantum level some classical symmetries are lost, and the case in which the classical symmetries are "deformed", i.e. the quantum space-time has as many symmetries as its classical counterpart but the nature of these symmetries is affected by the space-time quantization procedure. While some general features, such as the emergence of deformed dispersion relations, characterize both the symmetry-breaking case and the symmetry-deformation case, the two scenarios are also characterized by sharp differences, even concerning the nature of the new effects predicted. I illustrate this point within an illustrative calculation concerning the role of space-time symm...
Powering Africa's sustainable development: The potential role of nuclear energy
International Nuclear Information System (INIS)
Kessides, Ioannis N.
2014-01-01
The electricity deficit is one of the most serious contemporary issues facing sub-Saharan Africa. Many countries in the region have insufficient generation capacity to meet rapidly rising demand. Electricity shortages have become a binding and powerful constraint on the continent's sustainable development. Their resolution will require coordinated effort to improve the effectiveness and governance of the region's utilities and to significantly scale-up generation capacity. A broad portfolio of low carbon (low-C) technologies needs to be deployed in order to address the electricity deficit in a cost-effective way and not be disruptive to economic growth. Since nuclear power can deliver low-C electricity in bulk, reliably and without intermittency, it could make a significant contribution towards resolving Africa's power crisis. However, the post-Fukushima safety concerns related to large nuclear plants with substantial radioactive inventories will be especially pronounced in Africa. Moreover, large scale reactors with huge upfront investment requirements are likely to be unsuitable for capital-constrained African countries with small electricity grids. One promising direction for nuclear development in Africa might be to downsize reactors from the gigawatt scale to less-complex smaller units (with substantially smaller radioactive inventory) that are more affordable. - Highlights: • We examine the potential role of nuclear power in Africa. • There is growing African interest in nuclear power. • Nuclear power in Africa will require grid strengthening. • Small modular reactors could enhance Africa's energy security. • There are concerns about Africa's safety culture for nuclear power
Uliel, Livnat; Mellnick, Vincent M; Menias, Christine O; Holz, Andrew L; McConathy, Jonathan
2013-01-01
Nuclear medicine imaging provides valuable functional information that complements information obtained with anatomic imaging techniques in the evaluation of patients with specific acute clinical manifestations. Nuclear medicine studies are most often used in conjunction with other imaging modalities and as a problem-solving tool. Under certain circumstances a nuclear medicine study may be indicated as the first-line imaging modality, as in the case of renal scintigraphy for transplant dysfunction in the early postoperative period. Nuclear imaging may be preferred when a conventional first-line study is contraindicated or when it is important to minimize radiation exposure. The portability of nuclear imaging offers particular advantages for the evaluation of critically ill patients whose clinical condition is unstable and who cannot be safely transported out of the intensive care unit. The ability to visualize physiologic and pathophysiologic processes over relatively long time periods without adding to the patient's radiation exposure contributes to the high diagnostic sensitivity of several types of nuclear medicine studies. Viewing the acquired images in the cine mode adds to the value of these studies for diagnosing and characterizing dynamic abnormalities such as intermittent internal bleeding and bile or urine leakage. In this pictorial review, the spectrum of nuclear medicine studies commonly performed in the acute care setting is reviewed according to body systems and organs, with detailed descriptions of the indications, technical considerations, findings, and potential pitfalls of each type of study. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.332125098/-/DC1.
Strings, Branes and Symmetries
International Nuclear Information System (INIS)
Westerberg, A.
1997-01-01
Recent dramatic progress in the understanding of the non-perturbative structure of superstring theory shows that extended objects of various kinds, collectively referred to as p-branes, are an integral part of the theory. In this thesis, comprising an introductory text and seven appended research papers, we study various aspects of p-branes with relevance for superstring theory. The first part of the introductory text is a brief review of string theory focussing on the role of p-branes. In particular, we consider the so-called D-branes which currently are attracting a considerable amount of attention. The purpose of this part is mainly to put into context the results of paper 4, 5 and 6 concerning action functionals describing the low-energy dynamics of D-branes. The discussion of perturbative string theory given in this part of the introduction is also intended to provide some background to paper 2 which contains an application of the Reggeon-sewing approach to the construction of string vertices. The second part covers a rather different subject, namely higher-dimensional loop algebras and their cohomology, with the aim of facilitating the reading of papers 1, 3 and 7. The relation to p-branes is to be found in paper 1 where we introduce a certain higher-dimensional generalization of the loop algebra and discuss its potential applicability as a symmetry algebra for p-branes. Papers 3 and 7 are mathematically oriented out-growths of this paper addressing the issue of realizing algebras of this kind, known in physics as current algebras, in terms of pseudo differential operators (PSDOs). The main result of paper 3 is a proof of the equivalence between certain Lie-algebra cocycles on the space of second-quantizable PSDOs
The potential environmental impacts and the siting of proposed nuclear power plants in China
International Nuclear Information System (INIS)
Shi Zhongqi
1986-01-01
This paper reviews briefly the methodology of assessing environmental impacts from the nuclear power plants and analyses the potential radiological impacts on the environment from proposed nuclear power plants in China. Preliminary studies show that the environmental impacts of the effluents of routine release from PWRs to the proposed sites are extremely small, even if nuclear power plants are constructed either on the Bohai Sea shore with a narrow mouth or in the densely populated regions of Sunan. Thus, the suitability of sites depends mainly on the acceptability of possible exposure to the residents following postulated accidental release of radioactive materials. The paper also discusses relations between the nuclear plant siting and population distribution around the site and compares the distribution of the proposed sites in China with that of other countries sites in according to China actual situation, it is reasonable to adopt a prudent policy that the first series of nuclear power plants in China should be built in relatively low population areas
Schwichtenberg, Jakob
2018-01-01
This is a textbook that derives the fundamental theories of physics from symmetry. It starts by introducing, in a completely self-contained way, all mathematical tools needed to use symmetry ideas in physics. Thereafter, these tools are put into action and by using symmetry constraints, the fundamental equations of Quantum Mechanics, Quantum Field Theory, Electromagnetism, and Classical Mechanics are derived. As a result, the reader is able to understand the basic assumptions behind, and the connections between the modern theories of physics. The book concludes with first applications of the previously derived equations. Thanks to the input of readers from around the world, this second edition has been purged of typographical errors and also contains several revised sections with improved explanations. .
Energy Technology Data Exchange (ETDEWEB)
Chanowitz, M.S.
1990-09-01
The Higgs mechanism is reviewed in its most general form, requiring the existence of a new symmetry-breaking force and associated particles, which need not however be Higgs bosons. The first lecture reviews the essential elements of the Higgs mechanism, which suffice to establish low energy theorems for the scattering of longitudinally polarized W and Z gauge bosons. An upper bound on the scale of the symmetry-breaking physics then follows from the low energy theorems and partial wave unitarity. The second lecture reviews particular models, with and without Higgs bosons, paying special attention to how the general features discussed in lecture 1 are realized in each model. The third lecture focuses on the experimental signals of strong WW scattering that can be observed at the SSC above 1 TeV in the WW subenergy, which will allow direct measurement of the strength of the symmetry-breaking force. 52 refs., 10 figs.
Weiss, Asia; Whiteley, Walter
2014-01-01
This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme. Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology. The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...
Relativistic U(3) symmetry and pseudo-U(3) symmetry of the Dirac Hamiltonian
Energy Technology Data Exchange (ETDEWEB)
Ginocchio, Joseph N [Los Alamos National Laboratory
2010-01-01
The Dirac Hamiltonian with relativistic scalar and vector harmonic oscillator potentials has been solved analytically in two limits. One is the spin limit for which spin is an invariant symmetry of the the Dirac Hamiltonian and the other is the pseudo-spin limit for which pseudo-spin is an invariant symmetry of the Dirac Hamiltonian. The spin limit occurs when the scalar potential is equal to the vector potential plus a constant, and the pseudospin limit occurs when the scalar potential is equal in magnitude but opposite in sign to the vector potential plus a constant. Like the non-relativistic harmonic oscillator, each of these limits has a higher symmetry. For example, for the spherically symmetric oscillator, these limits have a U(3) and pseudo-U(3) symmetry respectively. We shall discuss the eigenfunctions and eigenvalues of these two limits and derive the relativistic generators for the U(3) and pseudo-U(3) symmetry. We also argue, that, if an anti-nucleon can be bound in a nucleus, the spectrum will have approximate spin and U(3) symmetry.
1991-06-01
AD-A245 256 The Potential Role of New Technology for Enhanced Safety and Performance of Nuclear Power Plants Through Improved Service Mainte c by Ted...man Department Graduate Committee Department of Nuclear Engineering 92-01536 -1- I 92 . t I The Potential Role of New Technology for Enhanced Saf and
International Nuclear Information System (INIS)
2000-01-01
The demand for energy, especially electricity, in developing countries is expected to grow rapidly in the coming decades as these countries seek to improve the living standards of their growing populations. Substantial growth in developing country energy demand plus a continued heavy reliance of the power sector on fossil fuels is likely to result in an increased dependence of these countries on energy imports and thus to potential deterioration of their terms-of-trade, reduced energy security and, in the absence of costly mitigation measures, severe degradation of the environment and public health, and will also lead to increasing emissions of greenhouse gases. If supply security, health and environmental protection and climate change become pressing policy issues, nuclear power is, in the short to medium term, the only viable non-fossil base load electricity generating alternative (other than hydro where growth potential is limited) that is already meeting 17% of global electricity needs and contributing more than 30% of electricity supplies in 14 countries. It is in the above context that the International Atomic Energy Agency organized this seminar to explore the role of nuclear power in meeting the growing demand for electricity in the developing world, and to identify and discuss suitable ways and means for proper implementation of nuclear power programmes in these countries. Several issues were discussed, in particular, the need and role of nuclear power; economic and financial aspects; technology transfer and national participation; safety, regulation and safeguards; and public acceptance
Measures with symmetry properties
Schindler, Werner
2003-01-01
Symmetries and invariance principles play an important role in various branches of mathematics. This book deals with measures having weak symmetry properties. Even mild conditions ensure that all invariant Borel measures on a second countable locally compact space can be expressed as images of specific product measures under a fixed mapping. The results derived in this book are interesting for their own and, moreover, a number of carefully investigated examples underline and illustrate their usefulness and applicability for integration problems, stochastic simulations and statistical applications.
International Nuclear Information System (INIS)
Chimento, Luis P.
2002-01-01
We find the group of symmetry transformations under which the Einstein equations for the spatially flat Friedmann-Robertson-Walker universe are form invariant. They relate the energy density and the pressure of the fluid to the expansion rate. We show that inflation can be obtained from nonaccelerated scenarios by a symmetry transformation. We derive the transformation rule for the spectrum and spectral index of the curvature perturbations. Finally, the group is extended to investigate inflation in the anisotropic Bianchi type-I spacetime and the brane-world cosmology
Symmetry, structure, and spacetime
Rickles, Dean
2007-01-01
In this book Rickles considers several interpretative difficulties raised by gauge-type symmetries (those that correspond to no change in physical state). The ubiquity of such symmetries in modern physics renders them an urgent topic in philosophy of physics. Rickles focuses on spacetime physics, and in particular classical and quantum general relativity. Here the problems posed are at their most pathological, involving the apparent disappearance of spacetime! Rickles argues that both traditional ontological positions should be replaced by a structuralist account according to which relational
Energy Technology Data Exchange (ETDEWEB)
Tenney, Rebeca M.; Bell, Christie L.; Wilson, James M., E-mail: wilsonjm@mail.med.upenn.edu
2014-04-15
Adeno-associated virus serotype 8 (AAV8) is a promising vector for liver-directed gene therapy. Although efficient uncoating of viral capsids has been implicated in AAV8's robust liver transduction, much about the biology of AAV8 hepatotropism remains unclear. Our study investigated the structural basis of AAV8 liver transduction efficiency by constructing chimeric vector capsids containing sequences derived from AAV8 and AAV2 – a highly homologous yet poorly hepatotropic serotype. Engineered vectors containing capsid variable regions (VR) VII and IX from AAV8 in an AAV2 backbone mediated near AAV8-like transduction in mouse liver, with higher numbers of chimeric genomes detected in whole liver cells and isolated nuclei. Interestingly, chimeric capsids within liver nuclei also uncoated similarly to AAV8 by 6 weeks after administration, in contrast with AAV2, of which a significantly smaller proportion were uncoated. This study links specific AAV capsid regions to the transduction ability of a clinically relevant AAV serotype. - Highlights: • We construct chimeric vectors to identify determinants of AAV8 liver transduction. • An AAV2-based vector with 17 AAV8 residues exhibited high liver transduction in mice. • This vector also surpassed AAV2 in cell entry, nuclear entry and onset of expression. • Most chimeric vector particles were uncoated at 6 weeks, like AAV8 and unlike AAV2. • Chimera retained heparin binding and was antigenically distinct from AAV2 and AAV8.
Proposed Nuclear Power Plants in the UK-Potential Radiological Implications for Ireland
International Nuclear Information System (INIS)
McMahon, C.; Kelleher, K.; McGinnity, P.; Organo, C.; Smith, K.; Currivan, L.; Ryan, T.
2013-05-01
The UK Government has identified up to eight locations for the construction of new nuclear power plants by 2025. Five of these locations are on the Irish Sea coast. The Radiological Protection Institute of Ireland, RPII was requested by the Minister for the Environment, Community and Local Government to undertake an assessment of the potential radiological impacts on Ireland from this New Build Programme. This report presents the findings of the potential impacts on Ireland of both the anticipated routine radioactive discharges and of a range of postulated nuclear accident scenarios. The following points are the principal findings of the report. Given the prevailing wind direction in Ireland, radioactive contamination in the air, either from routine operation of the proposed nuclear power plants or accidental releases, will most often be transported away from Ireland. The routine operation of the proposed nuclear power plants will have no measurable radiological impact on Ireland or the Irish marine environment. The severe accident scenarios assessed ranged in their estimated frequency of occurrance from 1 in 50,000 to 1 in 33 million per year. The assessment used a weather pattern that maximised the transfer of radioactivity to Ireland. For the severe accident scenarios assessed, food controls or agriculture protective measures would generally be required in Ireland to reduce exposure of the population so as to mitigate potential long-term health effects. In the accident scenario with an estimated 1 in 33 million chance of occurring, short-term measures such as staying indoors would also be advised as a precautionary measure. In general, the accidents with higher potential impact on Ireland are the ones least likely to occur. Regardless of the radiological impact, any accident at the proposed nuclear power plants leading to an increase of radioactivity levels in Ireland would have a socio-economic impact on Ireland. A major accidental release of radioactivity to
International Nuclear Information System (INIS)
1995-03-01
This is an appendix to a draft Environmental Impact Statement (EIS) on a proposed nuclear weapons nonproliferation policy concerning foreign research reactor spent nuclear fuel. This appendix describes the process used by the Department of Energy in selecting the potential ports of entry analyzed in this EIS. In addition the appendix provides the basic information required to evaluate ports and port activities, and the potential environmental impacts (incident-free and accidents) associated with the receipt and handling of foreign research reactor spent nuclear fuel from vessels to intermodal transport in ports
Interactions between constituent single symmetries in multiple symmetry.
Treder, Matthias Sebastian; van der Vloed, Gert; van der Helm, Peter A
2011-07-01
As a rule, the discriminability of multiple symmetries from random patterns increases with the number of symmetry axes, but this number does not seem to be the only determinant. In particular, multiple symmetries with orthogonal axes seem better discriminable than multiple symmetries with nonorthogonal axes. In six experiments on imperfect two-fold symmetry, we investigated whether this is due to extra structure in the form of so-called correlation rectangles, which arise only in the case of orthogonal axes, or to the relative orientation of the axes as such. The results suggest that correlation rectangles are not perceptually relevant and that the percept of a multiple symmetry results from an orientation-dependent interaction between the constituent single symmetries. The results can be accounted for by a model involving the analysis of symmetry at all orientations, smoothing (averaging over neighboring orientations), and extraction of peaks.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. Groups and Symmetry: A Guide to Discovering Mathematics. Geetha Venkataraman. Book Review Volume 4 Issue 10 October 1999 pp 91-92. Fulltext. Click here to view fulltext PDF. Permanent link:
Einmahl, John; Gan, Zhuojiong
Omnibus tests for central symmetry of a bivariate probability distribution are proposed. The test statistics compare empirical measures of opposite regions. Under rather weak conditions, we establish the asymptotic distribution of the test statistics under the null hypothesis; it follows that they
Symmetries in fundamental physics
Sundermeyer, Kurt
2014-01-01
Over the course of the last century it has become clear that both elementary particle physics and relativity theories are based on the notion of symmetries. These symmetries become manifest in that the "laws of nature" are invariant under spacetime transformations and/or gauge transformations. The consequences of these symmetries were analyzed as early as in 1918 by Emmy Noether on the level of action functionals. Her work did not receive due recognition for nearly half a century, but can today be understood as a recurring theme in classical mechanics, electrodynamics and special relativity, Yang-Mills type quantum field theories, and in general relativity. As a matter of fact, as shown in this monograph, many aspects of physics can be derived solely from symmetry considerations. This substantiates the statement of E.P.Wigner "... if we knew all the laws of nature, or the ultimate Law of nature, the invariance properties of these laws would not furnish us new information." Thanks to Wigner we now also underst...
Charged fluids with symmetries
Indian Academy of Sciences (India)
conformal Killing vector on the electromagnetic field tensor and the role of Maxwell's equations. 2. Conformal symmetries. Manifolds with structure may admit groups of transformations which preserve this struc- ture. A conformal motion preserves the metric up to a factor and maps null geodesics conformally. A conformal ...
Crumpecker, Cheryl
2003-01-01
Describes an art lesson used with children in the third grade to help them learn about symmetry, as well as encouraging them to draw larger than usual. Explains that students learn about the belief called "Horror Vacui" of the Northwest American Indian tribes and create their interpretation of this belief. (CMK)
Symmetries in fundamental physics
Sundermeyer, Kurt
2014-01-01
Over the course of the last century it has become clear that both elementary particle physics and relativity theories are based on the notion of symmetries. These symmetries become manifest in that the "laws of nature" are invariant under spacetime transformations and/or gauge transformations. The consequences of these symmetries were analyzed as early as in 1918 by Emmy Noether on the level of action functionals. Her work did not receive due recognition for nearly half a century, but can today be understood as a recurring theme in classical mechanics, electrodynamics and special relativity, Yang-Mills type quantum field theories, and in general relativity. As a matter of fact, as shown in this monograph, many aspects of physics can be derived solely from symmetry considerations. This substantiates the statement of E.P. Wigner "... if we knew all the laws of nature, or the ultimate Law of nature, the invariance properties of these laws would not furnish us new information." Thanks to Wigner we now also unders...
Jinzenji, Masao
2018-01-01
This book furnishes a brief introduction to classical mirror symmetry, a term that denotes the process of computing Gromov–Witten invariants of a Calabi–Yau threefold by using the Picard–Fuchs differential equation of period integrals of its mirror Calabi–Yau threefold. The book concentrates on the best-known example, the quintic hypersurface in 4-dimensional projective space, and its mirror manifold. First, there is a brief review of the process of discovery of mirror symmetry and the striking result proposed in the celebrated paper by Candelas and his collaborators. Next, some elementary results of complex manifolds and Chern classes needed for study of mirror symmetry are explained. Then the topological sigma models, the A-model and the B-model, are introduced. The classical mirror symmetry hypothesis is explained as the equivalence between the correlation function of the A-model of a quintic hyper-surface and that of the B-model of its mirror manifold. On the B-model side, the process of construct...
SYMMETRY OF COMPOSITE CRYSTALS
VANSMAALEN, S
1991-01-01
Composite crystals are crystals that consist of two or more subsystems, in first approximation each one having its own three-dimensional periodicity. The symmetry of these subsystems is then characterized by an ordinary space group. Due to their mutual interaction the true structure consists of a
Symmetries of Mücket-Treder's two-body problem
Mioc, V.
The two-body problem associated to the classical potential field proposed by Mücket and Treder (1977) is considered from the only standpoint of symmetries. The corresponding vector field in Hamiltonian or standard polar coordinates presents nice symmetries that form eight-element symmetric Abelian groups endowed with an idempotent structure. Expressed in Levi-Civita coordinates, the problem exhibits a sixteen-element group of symmetries, also Abelian and presenting an idempotent structure.
Investigation of potential fire-related damage to safety-related equipment in nuclear power plants
International Nuclear Information System (INIS)
Wanless, J.
1985-11-01
Based on a review of vendor information, fire damage reports, equipment qualification and hydrogen burn test results, and material properties, thirty-three types of equipment found in nuclear power plants were ranked in terms of their potential sensitivity to fire environments. The ranking considered both the functional requirements and damage proneness of each component. A further review of the seven top-ranked components was performed, considering the relative prevalence and potential safety significance of each. From this, relays and hand switches dominate as first choices for fire damage testing with logic equipment, power supplies, transmitters, and motor control centers as future candidates
Hu, Jinniu; Toki, Hiroshi; Shen, Hong
2016-10-18
We study the properties of nuclear matter with lattice nucleon-nucleon (NN) potential in the relativistic Brueckner-Hartree-Fock (RBHF) theory. To use this potential in such a microscopic many-body theory, we firstly have to construct a one-boson-exchange potential (OBEP) based on the latest lattice NN potential. Three mesons, pion, σ meson, and ω meson, are considered. Their coupling constants and cut-off momenta are determined by fitting the on-shell behaviors and phase shifts of the lattice force, respectively. Therefore, we obtain two parameter sets of the OBEP potential (named as LOBEP1 and LOBEP2) with these two fitting ways. We calculate the properties of symmetric and pure neutron matter with LOBEP1 and LOBEP2. In non-relativistic Brueckner-Hartree-Fock case, the binding energies of symmetric nuclear matter are around -3 and -5 MeV at saturation density, while it becomes -8 and -12 MeV in relativistic framework with 1 S 0 , 3 S 1 , and 3 D 1 channels using our two parameter sets. For the pure neutron matter, the equations of state in non-relativistic and relativistic cases are very similar due to only consideration 1 S 0 channel with isospin T = 1 case.
Rojas-Alcayaga, Gonzalo; Maturana, Andrea; Aitken, Juan-Pablo; Rojas, Carolina; Ortega, Ana-Verónica
2015-01-01
Background Deregulation of ?-catenin is associated with malignant transformation; however, its relationship with potentially malignant and malignant oral processes is not fully understood. The aim of this study was to determine and compare the nuclear ?-catenin expression in oral dysplasia and oral squamous cell carcinoma (OSCC). Material and Methods Cross sectional study. Immunodetection of ?-catenin was performed on 72 samples, with the following distribution: 21 mild dysplasia, 12 moderate dysplasia, severe dysplasia 3, 36 OSCC including 19 well differentiated, 15 moderately differentiated and 2 poorly differentiated. Through microscopic observation the number of positive cells per 1000 epithelial cells was counted. For the statistical analysis, the Kruskal Wallis test was used. Results Nuclear expression of ?-catenin was observed in all samples with severe and moderate dysplasia, with a median of 267.5, in comparison to mild dysplasia whose median was 103.75. Only 10 samples (27.7%) with OSCC showed nuclear expression, with statistically significant differences between groups (p < 0.05). Conclusions Our results are consistent with most of the reports which show increased presence of ?-catenin in severe and moderate dysplasia compared to mild dysplasia; however the expression of nuclear ?-catenin decreased after starting the invasive neoplastic process. This suggests a role for this protein in the progression of dysplasia and early malignant transformation to OSCC. Immunodetection of ?-catenin could be a possible immune marker in the detection of oral dysplasia. Key words:Oral squamous cell carcinoma (OSCC), ?-catenin, oral dysplasia. PMID:26241451
Reyes, Montserrat; Rojas-Alcayaga, Gonzalo; Maturana, Andrea; Aitken, Juan-Pablo; Rojas, Carolina; Ortega, Ana-Verónica
2015-09-01
Deregulation of β-catenin is associated with malignant transformation; however, its relationship with potentially malignant and malignant oral processes is not fully understood. The aim of this study was to determine and compare the nuclear β-catenin expression in oral dysplasia and oral squamous cell carcinoma (OSCC). Cross sectional study. Immunodetection of β-catenin was performed on 72 samples, with the following distribution: 21 mild dysplasia, 12 moderate dysplasia, severe dysplasia 3, 36 OSCC including 19 well differentiated, 15 moderately differentiated and 2 poorly differentiated. Through microscopic observation the number of positive cells per 1000 epithelial cells was counted. For the statistical analysis, the Kruskal Wallis test was used. Nuclear expression of β-catenin was observed in all samples with severe and moderate dysplasia, with a median of 267.5, in comparison to mild dysplasia whose median was 103.75. Only 10 samples (27.7%) with OSCC showed nuclear expression, with statistically significant differences between groups (p < 0.05). Our results are consistent with most of the reports which show increased presence of β-catenin in severe and moderate dysplasia compared to mild dysplasia; however the expression of nuclear β-catenin decreased after starting the invasive neoplastic process. This suggests a role for this protein in the progression of dysplasia and early malignant transformation to OSCC. Immunodetection of β-catenin could be a possible immune marker in the detection of oral dysplasia.
Assessment of the potential for radionuclide migration from a nuclear explosion cavity
International Nuclear Information System (INIS)
Hoffman, D.C.; Daniels, W.R.
1984-01-01
A field study of the distribution of radionuclides around an underground nuclear explosion cavity was initiated in 1974, about 9 years after detonation of the nuclear test. This study is part of the Radionuclide Migration (RNM) Project, a broad investigation to determine the rates of migration underground in various media at the Nevada Test Site (NTS) and the potential for movement both on and off the NTS of radioactivity from underground nuclear explosions. It was also envisaged that the study might provide data applicable to the underground disposal of radioactive waste. The site of the 0.75 kiloton nuclear test Cambric was chosen for a number of reasons. The Cambric explosion cavity is within the NTS Area 5 water-supply aquifer, and there was particular interest in possible contamination of water supplies. Also, the Cambric detonation point is only 294 meters below the ground surface, and thus the re-entry drilling and sampling operations would be less difficult and expensive than from some of the more deeply buried tests. The Cambric cavity region was re-entered, and a well was completed to a depth of 370 meters. Samples were taken to determine the radionuclide distribution between the solid material and water at the time of the experiment was started. Water was then pumped from a nearby satellite well to induce an artificial gradient sufficient to draw water from the Cambric cavity and provide an opportunity for the study of radionuclide migration under field conditions
Determining the current status and potential of nuclear medicine in Poland.
Pachocki, Krzysztof A; Sackiewicz-Slaby, Agata
2013-01-01
Through its use of ionising radiation, the field of nuclear medicine forms a unique and significant part of medical diagnostics and patient treatment. Objectives. To assess the operational potential of nuclear medicine in Poland based on existing database/literature sources together with conducting a survey on the relevant healthcare facilities available, staffing, expertise and performance. To gather all available literature data on the medical use of ionising radiation in Poland several data bases were used, since currently, there are no single statistical data base devoted to this issue. Data on radiation hygiene were thus collected from the Statistical Bulletin of the Ministry of Health, Annual reports from the National Atomic Energy Agency and Central Statistics Office. Additionally, national and provincial reports were used, as well as those received from the European Society of Nuclear Medicine. At present, the Public Healthcare system in Poland has 55 nuclear medicine departmental facilities operating and 8 that are private/non-public. These are staffed by 252 doctors, of whom 151 are qualified as nuclear medicine specialists; constituting one specialist per 300,000 inhabitants. In addition, 170 highly qualified staff (biologists, chemists, physicists, electronics engineers and IT specialists) provide indispensable scientific/operational support and are vital for the development of nuclear medicine departments. They are mainly responsible for ensuring that all equipment functions effectively and for developing new diagnostic techniques, together with new radiopharmaceuticals. Furthermore, there are approximately 500 other staff at intermediate-level also involved in nuclear medicine departments, such as technicians, nurses and support workers. The survey demonstrated an average of 22 persons employed per nuclear medicine department. For all institutions, it is estimated that there are 127 gamma cameras, 10 PET/CT scanners and 16 hybrid SPECT/CT systems
Chiral Symmetry, Heavy Quark Symmetry and Bound States
Yoshida, Yuhsuke
1995-01-01
I investigate the bound state problems of lowest-lying mesons and heavy mesons. Chiral symmetry is essential when one consider lowest-lying mesons. Heavy quark symmetry plays an central role in considering the semi-leptonic form factors of heavy mesons. Various properties based on the symmetries are revealed using Bethe-Salpeter equations.
Constraints on the symmetry energy from neutron star observations
International Nuclear Information System (INIS)
Newton, W G; Gearheart, M; Wen, De-Hua; Li, Bao-An
2013-01-01
The modeling of many neutron star observables incorporates the microphysics of both the stellar crust and core, which is tied intimately to the properties of the nuclear matter equation of state (EoS). We explore the predictions of such models over the range of experimentally constrained nuclear matter parameters, focusing on the slope of the symmetry energy at nuclear saturation density L. We use a consistent model of the composition and EoS of neutron star crust and core matter to model the binding energy of pulsar B of the double pulsar system J0737-3039, the frequencies of torsional oscillations of the neutron star crust and the instability region for r-modes in the neutron star core damped by electron-electron viscosity at the crust-core interface. By confronting these models with observations, we illustrate the potential of astrophysical observables to offer constraints on poorly known nuclear matter parameters complementary to terrestrial experiments, and demonstrate that our models consistently predict L < 70 MeV.
On Symmetries in Optimal Control
Schaft, A.J. van der
1986-01-01
We discuss the use of symmetries in solving optimal control problems. In particular a procedure for obtaining symmetries is given which can be performed before the actual calculation of the optimal control and optimal Hamiltonian.
Nuclear Spiral Shocks and Induced Gas Inflows in Weak Oval Potentials
Energy Technology Data Exchange (ETDEWEB)
Kim, Woong-Tae [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Elmegreen, Bruce G., E-mail: wkim@astro.snu.ac.kr, E-mail: bge@us.ibm.com [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)
2017-05-20
Nuclear spirals are ubiquitous in galaxy centers. They exist not only in strong barred galaxies but also in galaxies without noticeable bars. We use high-resolution hydrodynamic simulations to study the properties of nuclear gas spirals driven by weak bar-like and oval potentials. The amplitude of the spirals increases toward the center by a geometric effect, readily developing into shocks at small radii even for very weak potentials. The shape of the spirals and shocks depends rather sensitively on the background shear. When shear is low, the nuclear spirals are loosely wound and the shocks are almost straight, resulting in large mass inflows toward the center. When shear is high, on the other hand, the spirals are tightly wound and the shocks are oblique, forming a circumnuclear disk through which gas flows inward at a relatively lower rate. The induced mass inflow rates are enough to power black hole accretion in various types of Seyfert galaxies as well as to drive supersonic turbulence at small radii.
Small Modular Reactors: Nuclear Energy Market Potential for Near-term Deployment
International Nuclear Information System (INIS)
Lokhov, Alexey; Sozoniuk, Vladislav; Rothwell, Geoffrey; ); Cometto, Marco; Paillere, Henri; ); Crozat, Matt; Genoa, Paul; Joon Kim, Tae; McGough, Mike; Ingersoll, Dan; Rickman, Robin; Stout, Dan; Halnon, Greg; Chenais, Jacques; Briffod, Francois-Xavier; Perrier, Sylvain; Shahrokhi, Farshid; Kaufer, Barry; Wasylyk, Andrew; Shropshire, David; ); Danrong, Song; Swinburn, Richard
2016-01-01
Recent interest in small modular reactors (SMRs) is being driven by a desire to reduce the total capital costs associated with nuclear power plants and to provide power to small grid systems. According to estimates available today, if all the competitive advantages of SMRs were realised, including serial production, optimised supply chains and smaller financing costs, SMRs could be expected to have lower absolute and specific (per-kWe) construction costs than large reactors. Although the economic parameters of SMRs are not yet fully determined, a potential market exists for this technology, particularly in energy mixes with large shares of renewables. This report assesses the size of the market for SMRs that are currently being developed and that have the potential to broaden the ways of deploying nuclear power in different parts of the world. The study focuses on light water SMRs that are expected to be constructed in the coming decades and that strongly rely on serial, factory-based production of reactor modules. In a high-case scenario, up to 21 GWe of SMRs could be added globally by 2035, representing approximately 3% of total installed nuclear capacity. (authors)
Symmetry and topology in evolution
International Nuclear Information System (INIS)
Lukacs, B.; Berczi, S.; Molnar, I.; Paal, G.
1991-10-01
This volume contains papers of an interdisciplinary symposium on evolution. The aim of this symposium, held in Budapest, Hungary, 28-29 May 1991, was to clear the role of symmetry and topology at different levels of the evolutionary processes. 21 papers were presented, their topics included evolution of the Universe, symmetry of elementary particles, asymmetry of the Earth, symmetry and asymmetry of biomolecules, symmetry and topology of lining objects, human asymmetry etc. (R.P.)
Applications of Classical Scaling Symmetry
Bludman, Sidney
2011-01-01
Any symmetry reduces a second-order differential equation to a first-order equation: variational symmetries of the action (exemplified by central field dynamics) lead to conservation laws, but symmetries of only the equations of motion (exemplified by scale-invariant hydrostatics), yield first-order {\\em non-conservation laws} between invariants. We obtain these conservation laws by extending Noether's Theorem to non-variational symmetries, and present a variational formulation of spherical a...
Quantum symmetries in particle interactions
International Nuclear Information System (INIS)
Shirkov, D.V.
1983-01-01
The concept of a quantum symmetry is introduced as a symmetry in the formulation of which quantum representations and specific quantum notions are used essentially. Three quantum symmetry principles are discussed: the principle of renormalizability (possibly super-renormalizability), the principle of local gauge symmetry, and the principle of supersymmetry. It is shown that these principles play a deterministic role in the development of quantum field theory. Historically their use has led to ever stronger restrictions on the interaction mechanism of quantum fields
New approaches of the potential field for QPSO algorithm applied to nuclear reactor reload problem
International Nuclear Information System (INIS)
Nicolau, Andressa dos Santos; Schirru, Roberto
2015-01-01
Recently quantum-inspired version of the Particle Swarm Optimization (PSO) algorithm, Quantum Particle Swarm Optimization (QPSO) was proposed. The QPSO algorithm permits all particles to have a quantum behavior, where some sort of 'quantum motion' is imposed in the search process. When the QPSO is tested against a set of benchmarking functions, it showed superior performances as compared to classical PSO. The QPSO outperforms the classical one most of the time in convergence speed and achieves better levels for the fitness functions. The great advantage of QPSO algorithm is that it uses only one parameter control. The critical step or QPSO algorithm is the choice of suitable attractive potential field that can guarantee bound states for the particles moving in the quantum environment. In this article, one version of QPSO algorithm was tested with two types of potential well: delta-potential well harmonic oscillator. The main goal of this study is to show with of the potential field is the most suitable for use in QPSO in a solution of the Nuclear Reactor Reload Optimization Problem, especially in the cycle 7 of a Brazilian Nuclear Power Plant. All result were compared with the performance of its classical counterpart of the literature and shows that QPSO algorithm are well situated among the best alternatives for dealing with hard optimization problems, such as NRROP. (author)
International Nuclear Information System (INIS)
Gotchy, R.L.
1987-06-01
Estimates of mortality and morbidity are presented based on present-day knowledge of health effects resulting from current component designs and operations of the nuclear and coal fuel cycles, and anticipated emission rates and occupational exposure for the various fuel cycle facilities expected to go into operation during the next decade. The author concluded that, although there are large uncertainties in the estimates of potential health effects, the coal fuel cycle alternative has a greater health impact on man than the uranium fuel fycle. However, the increased risk of health effects for either fuel cycle represents a very small incremental risk to the average individual in the public for the balance of this century. The potential for large impacts exists in both fuel cycles, but the potential impacts associated with a runaway Greenhouse Effect from combustion of fossil fuels, such as coal, cannot yet be reasonably quantified. Some of the potential environmental impacts of the coal fuel cycle cannot currently be realistically estimated, but those that can appear greater than those from the nuclear fuel cycle. 103 refs., 1 fig., 18 tabs
Evidence of tensor correlations in the nuclear many-body system using a modern NN potential
International Nuclear Information System (INIS)
Fiase, J.O.; Nkoma, J.S.; Sharmaand, L.K.; Hosaka, A.
2003-01-01
In this paper we show evidence of the importance of tensor correlations in the nuclear many-body system by calculating the effective two-body nuclear matrix elements in the frame work of the Lowest-Order Constrained Variational (LOCV) technique with two-body correlation functions using the Reid93 potential. We have achieved this by switching on and off the strength of the tensor correlations, α k . We have found that in order to obtain reasonable agreement with earlier calculations based on the G-matrix theory, we must turn on the strength of the tensor correlations especially in the triplet even (TE) and tensor even (TNE) channels to take the value of approximately, 0.05. As an application, we have estimated the value of the Landau - Migdal parameter, g' NN which we found to be g' NN = 0.65. This compares favorably with the G-matrix calculated value of g' NN = 0.54. (author)
Potential contamination of surface water supplies by atmospheric releases from nuclear plants
International Nuclear Information System (INIS)
Codell, R.B.
1985-01-01
Atmospheric releases of radionuclides, which might result from severe accidents at nuclear power plants, have the potential for contaminating drinking water supplies. The probability and consequences of the contamination of a water supply for a large city is explored using the Indian Point Nuclear Station and New York City as an example. Techniques are developed to calculate the deposition of radionuclides onto the watersheds of the New York City reservoirs, and the extent to which the run-off from the watersheds would contaminate drinking water. It is possible to demonstrate that the supplies could be contaminated above 10 Code of Federal Regulations Part 20 drinking water limits and that population doses on the order of millions of person-rem could result from severe accidents. The relative (latent) risk of this pathway, however, would be small compared to other airborne pathway risks calculated for the same accidental release
Emergence of Symmetries from Entanglement
CERN. Geneva
2016-01-01
Maximal Entanglement appears to be a key ingredient for the emergence of symmetries. We first illustrate this phenomenon using two examples: the emergence of conformal symmetry in condensed matter systems and the relation of tensor networks to holography. We further present a Principle of Maximal Entanglement that seems to dictate to a large extend the structure of gauge symmetry.
Group analysis and renormgroup symmetries
International Nuclear Information System (INIS)
Kovalev, V.F.; Pustovalov, V.V.; Shirkov, D.V.
1996-01-01
An original regular approach to constructing special type symmetries for boundary-value problems, namely renormgroup symmetries, is presented. Different methods of calculating these symmetries based on modern group analysis are described. An application of the approach to boundary value problems is demonstrated with the help of a simple mathematical model. 35 refs
Broken symmetries in field theory
Kok, Mark Okker de
2008-01-01
The thesis discusses the role of symmetries in Quantum Field Theory. Quantum Field Theory is the mathematical framework to describe the physics of elementary particles. A symmetry here means a transformation under which the model at hand is invariant. Three types of symmetry are distinguished: 1.
The Potential Of Fission Nuclear Energy In Resolving Global Climate Change
International Nuclear Information System (INIS)
Pevec, D.
2015-01-01
There is an international consensus on the need of drastic reduction of carbon emission if very serious global climate changes are to be avoided. At present target is to limit global temperature increase to 2 Degrees of C and to keep CO 2 concentration below 450 ppm, though some recent request by climatologists argue for lower limit of 1.5 Degrees of C. The carbon emission reduction has to be done in the next few decades, as climate effects are essentially determined by integral emission. The integral emissions should not exceed 1000 Gt CO 2 to keep the probability of exceeding global temperature by 2 Degrees of C below 25 percent. Consequently, when we consider energy sources that could produce carbon free energy we have to concentrate on the period not later than 2060-2065. The sources that can take the burden of reduction in the years up to 2065 are Renewable Energy Sources (RES) and nuclear fission energy. The potential of RES has been estimated by many organizations and individuals. Their predictions indicate that RES are not likely to be sufficient to replace carbon emitters and fulfill the 2 Degrees of C limit requirements. The nuclear fission energy can give a very serious and hopefully timely (unlike nuclear fusion) contribution to reduction of emission. Even with proven conventional reactors using once through fuel cycle without fuel reprocessing the nuclear build-up in the years 2025-2065 could reach 3330 GW. With this concept nuclear contribution of 94.5 EJ/y would be reached by 2065, while integral CO 2 emission savings would be about 500 Gt CO 2 by 2065. This shows that essential nuclear contribution is possible without the use of plutonium and fast breeders, technology not ready for climate-critical next 50 years and not acceptable in present political environment. This nuclear fission energy contribution along with contributions from renewable sources, energy saving, and increased efficiency in energy use can solve the climate problems. (author).
Isospin-dependent properties of asymmetric nuclear matter in relativistic mean field models
Chen, Lie-Wen; Ko, Che Ming; Li, Bao-An
2007-11-01
Using various relativistic mean-field models, including nonlinear ones with meson field self-interactions, models with density-dependent meson-nucleon couplings, and point-coupling models without meson fields, we have studied the isospin-dependent bulk and single-particle properties of asymmetric nuclear matter. In particular, we have determined the density dependence of nuclear symmetry energy from these different relativistic mean-field models and compared the results with the constraints recently extracted from analyses of experimental data on isospin diffusion and isotopic scaling in intermediate energy heavy-ion collisions as well as from measured isotopic dependence of the giant monopole resonances in even-A Sn isotopes. Among the 23 parameter sets in the relativistic mean-field model that are commonly used for nuclear structure studies, only a few are found to give symmetry energies that are consistent with the empirical constraints. We have also studied the nuclear symmetry potential and the isospin splitting of the nucleon effective mass in isospin asymmetric nuclear matter. We find that both the momentum dependence of the nuclear symmetry potential at fixed baryon density and the isospin splitting of the nucleon effective mass in neutron-rich nuclear matter depend not only on the nuclear interactions but also on the definition of the nucleon optical potential.
A broken symmetry ontology: Quantum mechanics as a broken symmetry
International Nuclear Information System (INIS)
Buschmann, J.E.
1988-01-01
The author proposes a new broken symmetry ontology to be used to analyze the quantum domain. This ontology is motivated and grounded in a critical epistemological analysis, and an analysis of the basic role of symmetry in physics. Concurrently, he is led to consider nonheterogeneous systems, whose logical state space contains equivalence relations not associated with the causal relation. This allows him to find a generalized principle of symmetry and a generalized symmetry-conservation formalisms. In particular, he clarifies the role of Noether's theorem in field theory. He shows how a broken symmetry ontology already operates in a description of the weak interactions. Finally, by showing how a broken symmetry ontology operates in the quantum domain, he accounts for the interpretational problem and the essential incompleteness of quantum mechanics. He proposes that the broken symmetry underlying this ontological domain is broken dilation invariance
Strong Electroweak Symmetry Breaking
Grinstein, Benjamin
2011-01-01
Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...
Leadership, power and symmetry
DEFF Research Database (Denmark)
Spaten, Ole Michael
2016-01-01
Research publications concerning managers who coach their own employees are barely visible despite its wide- spread use in enterprises (McCarthy & Milner, 2013; Gregory & Levy, 2011; Crabb, 2011). This article focuses on leadership, power and moments of symmetry in the coaching relationship...... regarding managers coaching their employees and it is asked; what contributes to coaching of high quality when one reflects on the power aspect as being immanent? Fourteen middle managers coached five of their employees, and all members of each party wrote down cues and experiences immediately after each...... session. Thereafter we executed qualitative interviews with both managers and employees. Subsequently, a Thematic Analysis resulted in several themes, including power and moments of symmetry in the coaching relationship. One main conclusion is that the most fruitful coaching was obtained when the coachee...
Asymmetry, Symmetry and Beauty
Directory of Open Access Journals (Sweden)
Abbe R. Kopra
2010-07-01
Full Text Available Asymmetry and symmetry coexist in natural and human processes. The vital role of symmetry in art has been well demonstrated. This article highlights the complementary role of asymmetry. Further we show that the interaction of asymmetric action (recursion and symmetric opposition (sinusoidal waves are instrumental in generating creative features (relatively low entropy, temporal complexity, novelty (less recurrence in the data than in randomized copies and complex frequency composition. These features define Bios, a pattern found in musical compositions and in poetry, except for recurrence instead of novelty. Bios is a common pattern in many natural and human processes (quantum processes, the expansion of the universe, gravitational waves, cosmic microwave background radiation, DNA, physiological processes, animal and human populations, and economic time series. The reduction in entropy is significant, as it reveals creativity and contradicts the standard claim of unavoidable decay towards disorder. Artistic creations capture fundamental features of the world.
de Boer, Jan; Freivogel, Ben; Kabir, Laurens; Lokhande, Sagar F.
2017-07-01
In the AdS/CFT correspondence, bulk information appears to be encoded in the CFT in a redundant way. A local bulk field corresponds to many different non-local CFT operators (precursors). We recast this ambiguity in the language of BRST symmetry, and propose that in the large N limit, the difference between two precursors is a BRST exact and ghost-free term. This definition of precursor ambiguities has the advantage that it generalizes to any gauge theory. Using the BRST formalism and working in a simple model with global symmetries, we re-derive a precursor ambiguity appearing in earlier work. Finally, we show within this model that the obtained ambiguity has the right number of parameters to explain the freedom to localize precursors within different spatial regions of the boundary order by order in the large N expansion.
International Nuclear Information System (INIS)
Bunakov, V.E.; Ivanov, I.B.
1999-01-01
Connections between the symmetries of Hamiltonian systems in classical and quantum mechanics, on one hand, and their regularity or chaoticity, on the other hand, are considered. The quantum-chaoticity criterion that was proposed previously and which was borrowed from the theory of compound-nucleus resonances is used to analyze the quantum diamagnetic Kepler problem - that is, the motion of a spinless charged particle in a Coulomb and a uniform magnetic field
International Nuclear Information System (INIS)
Herrero, O F
2010-01-01
Music and Physics are very close because of the symmetry that appears in music. A periodic wave is what music really is, and there is a field of Physics devoted to waves researching. The different musical scales are the base of all kind of music. This article tries to show how this musical scales are made, how the consonance is the base of many of them and how symmetric they are.
Symmetry and quantum mechanics
Corry, Scott
2016-01-01
This book offers an introduction to quantum mechanics for professionals, students, and others in the field of mathematics who have a minimal background in physics with an understanding of linear algebra and group theory. It covers such topics as Lie groups, algebras and their representations, and analysis (Hilbert space, distributions, the spectral Theorem, and the Stone-Von Neumann Theorem). The book emphasizes the role of symmetry and is useful to physicists as it provides a mathematical introduction to the topic.
Energy Technology Data Exchange (ETDEWEB)
Herrero, O F, E-mail: o.f.herrero@hotmail.co [Conservatorio Superior de Musica ' Eduardo Martinez Torner' Corrada del Obispo s/n 33003 - Oviedo - Asturias (Spain)
2010-06-01
Music and Physics are very close because of the symmetry that appears in music. A periodic wave is what music really is, and there is a field of Physics devoted to waves researching. The different musical scales are the base of all kind of music. This article tries to show how this musical scales are made, how the consonance is the base of many of them and how symmetric they are.
Relativistic pseudospin symmetry and shell model Hamiltonians that conserve pseudospin symmetry
Energy Technology Data Exchange (ETDEWEB)
Ginocchio, Joseph N [Los Alamos National Laboratory
2010-09-21
Professor Akito Arima and his colleagues discovered 'pseudospin' doublets forty-one years ago in spherical nuclei. These doublets were subsequently discovered in deformed nuclei. We show that pseudospin symmetry is an SU(2) symmetry of the Dirac Hamiltonian which occurs when the scalar and vector potentials are opposite in sign but equal in magnitude. This symmetry occurs independent of the shape of the nucleus: spherical, axial deformed, triaxial, and gamma unstable. We survey some of the evidence that pseudospin symmetry is approximately conserved for a Dirac Hamiltonian with realistic scalar and vector potentials by examining the energy spectra, the lower components of the Dirac eigenfunctions, the magnetic dipole and Gamow-Teller transitions in nuclei, the upper components of the Dirac eigenfunctions, and nucleon-nucleus scattering. We shall also suggest that pseudospin symmetry may have a fundamental origin in chiral symmetry breaking by examining QCD sum rules. Finally we derive the shell model Hamiltonians which conserve pseudospin and show that they involve tensor interactions.
Thermochemical modeling of nuclear fuel and the effects of oxygen potential buffers
Loukusa, Henri; Ikonen, Timo; Valtavirta, Ville; Tulkki, Ville
2016-12-01
The elemental and chemical composition of nuclear fuel pellets are key factors influencing the material properties of the pellets. The oxidation state of the fuel is one of the most important chemical properties influencing the material properties of the fuel, and it can only be determined with the knowledge of the chemical composition. A measure of the oxidation state is the oxygen chemical potential of the fuel. It can be buffered by redox pairs, such as the well-known Mo/MoO2 pair. In this work, the elemental composition of the fuel is obtained from a burnup calculation and the temperature and pressure calculated with a fuel performance code. An estimate of the oxygen potential of fuel is calculated with Gibbs energy minimization. The results are compared against experimental data from the literature. The significance of the UMoO6 compound and its buffering effect on the oxygen potential is emphasized.
Potential human factors research relating to modern technology in nuclear power plants
International Nuclear Information System (INIS)
Ketchel, J.; Fink, R.; Hanes, L.; Williges, R.; Williges, B.
1994-01-01
This paper discusses proposed human factors research to address advanced human-machine interface technology in nuclear power plants. It relates to a current EPRI project to identify a prioritized list of specific research issues that could be assessed to improve control room and other user interface areas. The project seeks to bridge the gap between the functional requirements of advanced design initiatives and the human factors research needed to support them. It seeks to identify potential benefits to be expected, as well as potential problems that might be introduced by advanced technology. It provides an organized approach to identifying human factors research needs, information already available, and measures of performance and effectiveness that might be used to assess the value of potential improvements. Those parts of the proposed plan that are subsequently approved by EPRI management and by the utility advisory committee will provide a basis for recommending research priorities
Spontaneous breakdown of PT symmetry in the complex Coulomb ...
Indian Academy of Sciences (India)
Keywords. Spontaneous breakdown of PT symmetry; Coulomb potential; complex en- ergy eigenvalues. PACS Nos 03.65.Ge; 03.65.Nk; 11.30.Er. 1. Introduction. One of the most intriguing features of PT -symmetric quantum mechanics is the spontaneous breakdown of PT symmetry. This phenomenon was noted in the first.
Symmetries for SM Alignment in multi-Higgs Doublet Models
Pilaftsis, Apostolos
2016-01-01
We derive the complete set of maximal symmetries for Standard Model (SM) alignment that may occur in the tree-level scalar potential of multi-Higgs Doublet Models, with $n > 2$ Higgs doublets. Our results generalize the symmetries of SM alignment, without decoupling of large mass scales or fine-tuning, previously obtained in the context of two-Higgs Doublet Models.
Implications of dynamical symmetry breaking for high energy experiments
International Nuclear Information System (INIS)
Ali, A.
1981-06-01
A scenario of dynamical symmetry breaking as an alternative to the canonical Higgs mechanism with elementary spin-O fields is described, and its implications for high energy experiments contrasted with those of the canonical theory. The potential role of e + e - annihilation physics in unravelling the nature of spontaneous symmetry breaking is emphasized. (orig.)
Pole Inflation - Shift Symmetry and Universal Corrections
Broy, Benedict J.; Galante, Mario; Roest, Diederik; Westphal, Alexander
2015-01-01
An appealing explanation for the Planck data is provided by inflationary models with a singular non-canonical kinetic term: a Laurent expansion of the kinetic function translates into a potential with a nearly shift-symmetric plateau in canonical fields. The shift symmetry can be broken at large
The "ghost" symmetry in the CKP hierarchy
Cheng, Jipeng; He, Jingsong
2014-06-01
In this paper, we systematically study the "ghost" symmetry in the CKP hierarchy through its actions on the Lax operator, dressing operator, eigenfunctions and the tau function. In this process, the spectral representation of the eigenfunction is developed and the squared eigenfunction potential is investigated.
Chiral symmetry breaking in finite quantum electrodynamics
International Nuclear Information System (INIS)
Montero, J.C.; Pleitez, V.
1987-01-01
The dynamical breakdown of chiral symmetry in a finite Abelian gauge theory using a variational approach for the effective potential for composite operators is discussed. It is shown that, at least in a variational approach, the fermion either remains massless or gets a dynamical mass for every non-zero coupling constant. (Author) [pt
Symmetry characterization of electrons and lattice excitations
Directory of Open Access Journals (Sweden)
Schober H.
2012-03-01
Full Text Available Symmetry concerns all aspects of a physical system from the electronic orbitals to structural and magnetic excitations. In this article we will try to elaborate the fundamental connection between symmetry and excitations. As excitations are manyfold in physical systems it is impossible to treat them exhaustively. We thus concentrate on the two topics of Bloch electrons and phonons. These two examples are complementary in the sense that Bloch electrons describe single particles in an external periodic potential while phonons exemplify a decoupled system of interacting particles. The way we develop the argument gives as by-product a short account of molecular orbitals and molecular vibrations.
Abnormal behavior of the optical potential for the halo nuclear system 6He+209Bi
Yang, L.; Lin, C. J.; Jia, H. M.; Wang, D. X.; Ma, N. R.; Sun, L. J.; Yang, F.; Xu, X. X.; Wu, Z. D.; Zhang, H. Q.; Liu, Z. H.
2017-10-01
In a recent transfer reaction measurement of 208Pb(7Li,6He )209Bi at energies around and below the Coulomb barrier, the optical model potentials of the halo nuclear system 6He+209Bi were extracted by fitting the experimental data with the theoretical frameworks of the distorted-wave Born approximation and coupled reaction channels, respectively. With the high-precision result, a complete picture of the behavior of the optical potential for this halo system is clearly derived for the first time. The real potential presents a bell-like shape around the barrier as a normal threshold anomaly. However, for the imaginary part, it first increases with the energy decreasing below the barrier and then falls quickly to 0, hence the threshold energy can be determined by fitting the variation trend. Moreover, the result also provides some evidence that the dispersion relation does not hold for this halo nuclear system, which calls for further investigation of the underlying physics.
Support to other nuclear waste disposal programmes considering clay as a potential host rock
International Nuclear Information System (INIS)
Volckaert, G.
2009-01-01
SCK-CEN started to study the Boom Clay as potential host rock for nuclear waste disposal in 1974. Since then, SCK-CEN has been involved in other international projects studying clay as potential host rock in order to get a broader support for disposal in clay and to acquire broader insight in clay behaviour. Besides Belgium, France and Switzerland are currently investigating clay formations as potential host rock for the disposal of radioactive waste. In the Netherlands, clay formations have always been considered as an alternative to disposal in salt. The general interest in clays is increasing: in Germany and The United Kingdom, it was decided a few years ago that besides respectively salt and crystalline rock also clays need to be evaluated. In Eastern and Central Europe, the Slovak republic and Lithuania consider both clay and granite as possible host rocks for spent fuel while in Russia recently a project was started to study the possible disposal of low and medium level waste in a clay formation in the Leningrad area. Within the EC research and development framework programs and the OECD/NEA Clay Club, collaborations were developed between countries studying clay and with a strong involvement of SCK-CEN. The collaboration with the Eastern and Central European countries is supported through the support programme of the Belgian Ministry of Economic affairs. The objectives of these co-operations are to deliver expert services to other nuclear waste disposal programs considering clay as host rock; to to acquire broader international recognition of our expertise and support for the development of nuclear waste disposal in clay; to get a broader insight in the properties and behaviour of clays
Bilateral symmetry analysis of breast MRI
International Nuclear Information System (INIS)
Alterson, Robert; Plewes, Donald B
2003-01-01
Mammographic interpretation often uses symmetry between left and right breasts to indicate the site of potential tumour masses. This approach has not been applied to breast images obtained from MRI. We present an automatic technique for breast symmetry detection based on feature extraction techniques which does not require any efforts to co-register breast MRI data. The approach applies computer-vision techniques to detect natural biological symmetries in breast MR scans based on three objective measures of similarity: multiresolution non-orthogonal wavelet representation, three-dimensional intensity distributions and co-occurrence matrices. Statistical distributions that are invariant to feature localization are computed for each of the extracted image features. These distributions are later compared against each other to account for perceptual similarity. Studies based on 51 normal MRI scans of randomly selected patients showed that the sensitivity of symmetry detection rate approached 94%. The symmetry analysis procedure presented in this paper can be applied as an aid in detecting breast tissue changes arising from disease
Gauged discrete symmetries and proton stability
International Nuclear Information System (INIS)
Mohapatra, Rabindra N.; Ratz, Michael
2007-01-01
We discuss the results of a search for anomaly-free Abelian Z N discrete symmetries that lead to automatic R-parity conservation and prevent dangerous higher-dimensional proton decay operators in simple extensions of minimal supersymmetric extension of the standard model based on the left-right symmetric group, the Pati-Salam group and SO(10). We require that the superpotential for the models have enough structures to be able to give correct symmetry breaking to minimal supersymmetric extension of the standard model and potentially realistic fermion masses. We find viable models in each of the extensions, and for all the cases, anomaly freedom of the discrete symmetry restricts the number of generations
Potential Signatures of Semi-volatile Compounds Associated With Nuclear Processing
Energy Technology Data Exchange (ETDEWEB)
Probasco, Kathleen M.; Birnbaum, Jerome C.; Maughan, A. D.
2002-06-01
Semi-volatile chemicals associated with nuclear processes (e.g., the reprocessing of uranium to produce plutonium for nuclear weapons, or the separation of actinides from processing waste streams), can provide sticky residues or signatures that will attach to piping, ducting, soil, water, or other surface media. Volatile compounds, that are more suitable for electro-optical sensing, have been well studied. However, the semi-volatile compounds have not been well documented or studied. A majority of these semi-volatile chemicals are more robust than typical gaseous or liquid chemicals and can have lifetimes of several weeks, months, or years in the environment. However, large data gaps exist concerning these potential signature compounds and more research is needed to fill these data gaps so that important signature information is not overlooked or discarded. This report investigates key semi-volatile compounds associated with nuclear separations, identifies available chemical and physical properties, and discusses the degradation products that would result from hydrolysis, radiolysis and oxidation reactions on these compounds.
Economic Analyses and Potential Market of the 200MW Nuclear Heating Reactor
International Nuclear Information System (INIS)
Wang, Yongqing; Wang, Guiying
1992-01-01
Based on the 5MW experimental nuclear heating reactor, Intent has developed a 200MW demonstration nuclear heating reactor. Owing to its simplified systems and low operating parameters, the NCR-200 has preferable investment in comparison with that of a nuclear power plant. The pre-feasibility studies for several cities in Northern China have shown that the heat cost of a NCR-200 can be competitive with a coal fired heating plant. As a safe, clean and economic heat source, the NCR could pose a large market in replacement of coal for heating. The R and D work performed up to now has demonstrated that the NCR-200 operating under the present parameters can supply low pressure steam for industrial process and co-generation to enhance it economic benefit. The NCR-200 could also serve a heat source for air condition by using Li Br refrigerator, this application is very interesting to some cities in Central and Southern China. The applications of the NCR in oil recovery by injecting hot water and transportation are very promising for some oil fields in North China. In addition, the study on sea water desalination using the NCR-200 is being carried out at present under international cooperation. All of these will expansion the possible application of the NCR. The paper presents the economic analysis and the potential market of the NCR-200
Hrncir, Tomas; Strazovec, Roman; Zachar, Matej
2017-09-07
The decommissioning of nuclear installations represents a complex process resulting in the generation of large amounts of waste materials containing various concentrations of radionuclides. Selection of an appropriate strategy of management of the mentioned materials strongly influences the effectiveness of decommissioning process keeping in mind safety, financial and other relevant aspects. In line with international incentives for optimization of radioactive material management, concepts of recycling and reuse of materials are widely discussed and applications of these concepts are analysed. Recycling of some portion of these materials within nuclear sector (e.g. scrap metals or concrete rubble) seems to be highly desirable from economical point of view and may lead to conserve some disposal capacity. However, detailed safety assessment along with cost/benefit calculations and feasibility study should be developed in order to prove the safety, practicality and cost effectiveness of possible recycling scenarios. Paper discussed the potential for recycling of slightly radioactive metals arising from decommissioning of NPPs within nuclear sector in Slovakia. Various available recycling scenarios are introduced and method for overall assessment of various recycling scenarios is outlined including the preliminary assessment of safety and financial aspects. Copyright © 2017 Elsevier Ltd. All rights reserved.
Utilization of Used Nuclear Fuel in a Potential Future US Fuel Cycle Scenario - 13499
International Nuclear Information System (INIS)
Worrall, Andrew
2013-01-01
To date, the US reactor fleet has generated approximately 68,000 MTHM of used nuclear fuel (UNF) and even with no new nuclear build in the US, this stockpile will continue to grow at approximately 2,000 MTHM per year for several more decades. In the absence of reprocessing and recycle, this UNF is a liability and needs to be dealt with accordingly. However, with the development of future fuel cycle and reactor technologies in the decades ahead, there is potential for UNF to be used effectively and efficiently within a future US nuclear reactor fleet. Based on the detailed expected operating lifetimes, the future UNF discharges from the existing reactor fleet have been calculated on a yearly basis. Assuming a given electricity demand growth in the US and a corresponding growth demand for nuclear energy via new nuclear build, the future discharges of UNF have also been calculated on a yearly basis. Using realistic assumptions about reprocessing technologies and timescales and which future fuels are likely to be reprocessed, the amount of plutonium that could be separated and stored for future reactor technologies has been determined. With fast reactors (FRs) unlikely to be commercially available until 2050, any new nuclear build prior to then is assumed to be a light water reactor (LWR). If the decision is made for the US to proceed with reprocessing by 2030, the analysis shows that the UNF from future fuels discharged from 2025 onwards from the new and existing fleet of LWRs is sufficient to fuel a realistic future demand from FRs. The UNF arising from the existing LWR fleet prior to 2025 can be disposed of directly with no adverse effect on the potential to deploy a FR fleet from 2050 onwards. Furthermore, only a proportion of the UNF is required to be reprocessed from the existing fleet after 2025. All of the analyses and conclusions are based on realistic deployment timescales for reprocessing and reactor deployment. The impact of the delay in recycling the UNF
Symmetry-dictated trucation: Solutions of the spherical shell model for heavy nuclei
International Nuclear Information System (INIS)
Guidry, M.W.
1992-01-01
Principles of dynamical symmetry are used to simplify the spherical shell model. The resulting symmetry-dictated truncation leads to dynamical symmetry solutions that are often in quantitative agreement with a variety of observables. Numerical calculations, including terms that break the dynamical symmetries, are shown that correspond to shell model calculations for heavy deformed nuclei. The effective residual interaction is simple, well-behaved, and can be determined from basic observables. With this approach, we intend to apply the shell model in systematic fashion to all nuclei. The implications for nuclear structure far from stability and for nuclear masses and other quantities of interest in astrophysics are discussed
Symmetries of nonlinear ordinary differential equations: The ...
Indian Academy of Sciences (India)
2015-10-21
Oct 21, 2015 ... Abstract. Lie symmetry analysis is one of the powerful tools to analyse nonlinear ordinary dif- ferential equations. We review the effectiveness of this method in terms of various symmetries. We present the method of deriving Lie point symmetries, contact symmetries, hidden symmetries, nonlocal symmetries ...
Demontis, F.; Ortenzi, G.; van der Mee, C.
2018-04-01
By following the ideas presented by Fukumoto and Miyajima in Fukumoto and Miyajima (1996) we derive a generalized method for constructing integrable nonlocal equations starting from any bi-Hamiltonian hierarchy supplied with a recursion operator. This construction provides the right framework for the application of the full machinery of the inverse scattering transform. We pay attention to the Pohlmeyer-Lund-Regge equation coming from the nonlinear Schrödinger hierarchy and construct the formula for the reflectionless potential solutions which are generalizations of multi-solitons. Some explicit examples are discussed.
International Nuclear Information System (INIS)
Cantarel, Vincent; Motooka, Takafumi; Yamagishi, Isao
2017-06-01
After a necessary decay time, the zeolites used for the water decontamination will eventually be conditioned for their long-term storage. Geopolymer is considered as a potential matrix to manage radioactive cesium and strontium containing waste. For such applications, a correct comprehension of the binder structure, its macroscopic properties, its interactions with the waste and the physico-chemical phenomena occurring in the wasteform is needed to be able to judge of the soundness and viability of the material. Although the geopolymer is a young binder, a lot of research has been carried out over the last fifty years and our understanding of this matrix and its potential applications is progressing fast. This review aims at gathering the actual knowledge on geopolymer studies about geopolymer composites, geopolymer as a confinement matrix for nuclear wastes and geopolymer under irradiation. This information will finally provide guidance for the future studies and experiments. (author)
Under-examined aspects of the potential environmental effects of nuclear war
Energy Technology Data Exchange (ETDEWEB)
MacCracken, M.C.; Penner, J.E.
1987-07-01
In addition to destroying the area near the explosions, a nuclear war would lead to injection of a wide range of substances into the environment, both as a result of the delivery systems and explosions themselves and as a consequence of the blast, fires, and resulting destruction and disruption. While addressing the many remaining uncertainties concerning the effects of smoke injections on climate is the major topic of present research, there are a number of other potential impacts that could have major consequences, but which are currently poorly understood and have not yet been carefully examined. These under-examined effects include perturbations to atmospheric chemistry, the effects of injections of dust and water (which could create ice particles), the consequences of emissions from the smoldering phase of the fires, resuspension of materials due to perturbed surface conditions, and a range of other potential consequences.
Industrial environmental monitoring in non nuclear industry which potential to generate TENORM
International Nuclear Information System (INIS)
Constitution of the Republic of Indonesia Year 1945 states that the environment is good and healthy life is a human rights and constitutional rights of every citizen of Indonesia. In Indonesia has many industrial and mining activities that produce Norm (Naturally occurring Radioactive Materials) and TENORM (technologically Enhanced Naturally occurring Radioactive Materials). TENORM is a natural radioactive material which due to human activity or process technology increases the potential exposure when compared to the initial state and the potential radiological impact either external or internal radiation exposure. BAPETEN must ensure that the activities undertaken by non-nuclear industry, especially in the handling of radioactive waste at Norm and TENORM which can lead to chronic exposure, carried out securely and safely, both for workers, public and the environment. (author)
Under-examined aspects of the potential environmental effects of nuclear war
International Nuclear Information System (INIS)
MacCracken, M.C.; Penner, J.E.
1987-07-01
In addition to destroying the area near the explosions, a nuclear war would lead to injection of a wide range of substances into the environment, both as a result of the delivery systems and explosions themselves and as a consequence of the blast, fires, and resulting destruction and disruption. While addressing the many remaining uncertainties concerning the effects of smoke injections on climate is the major topic of present research, there are a number of other potential impacts that could have major consequences, but which are currently poorly understood and have not yet been carefully examined. These under-examined effects include perturbations to atmospheric chemistry, the effects of injections of dust and water (which could create ice particles), the consequences of emissions from the smoldering phase of the fires, resuspension of materials due to perturbed surface conditions, and a range of other potential consequences
Sixth Meeting on CPT and Lorentz Symmetry
CPT and Lorentz Symmetry
2014-01-01
This book contains the Proceedings of the Sixth Meeting on CPT and Lorentz Symmetry, held at Indiana University in Bloomington on June 17–21, 2013. The Meeting focused on tests of these fundamental symmetries and on related theoretical issues, including scenarios for possible violations. Topics covered at the meeting include searches for CPT and Lorentz violations involving: accelerator and collider experiments; atomic, nuclear, and particle decays; birefringence, dispersion, and anisotropy in cosmological sources; clock-comparison measurements; electromagnetic resonant cavities and lasers; tests of the equivalence principle; gauge and Higgs particles; high-energy astrophysical observations; laboratory tests of gravity; matter interferometry; neutrino oscillations and propagation; oscillations and decays of neutral mesons; particle–antiparticle comparisons; post-newtonian gravity in the solar system and beyond; second- and third-generation particles; space-based missions; spectroscopy of hydrogen and ant...
International Nuclear Information System (INIS)
Carr, M.D.; Yount, J.C.
1988-01-01
Yucca Mountain in southern Nye County, Nevada, has been selected by the United States Department of Energy as one of three potential sites for the nation's first high-level nuclear waste repository. Its deep water table, closed-basin ground-water flow, potentially favorable host rock, and sparse population have made the Yucca Mountain area a viable candidate during the search for a nuclear waste disposal site. Yucca Mountain, however, lies within the southern Great Basin, a region of known contemporary tectonism and young volcanic activity, and the characterization of tectonism and volcanism remains as a fundamental problem for the Yucca Mountain site. The United States Geological Survey has been conducting extensive studies to evaluate the geologic setting of Yucca Mountain, as well as the timing and rates of tectonic and volcanic activity in the region. A workshop was convened by the Geologic Survey in Denver, Colorado, on August 19, 20, and 21, 1985, to review the scientific progress and direction of these studies. Considerable debate resulted. This collection of papers represents the results of some of the studies presented at the workshop, but by no means covers all of the scientific results and viewpoints presented. Rather, the volume is meant to serve as a progress report on some of the studies within the Geological Survey's continuing research program toward characterizing the tectonic framework of Yucca Mountain. Individual papers were processed separately for the data base
Energy Technology Data Exchange (ETDEWEB)
Carr, M.D.; Yount, J.C. (eds.)
1988-12-31
Yucca Mountain in southern Nye County, Nevada, has been selected by the United States Department of Energy as one of three potential sites for the nation`s first high-level nuclear waste repository. Its deep water table, closed-basin ground-water flow, potentially favorable host rock, and sparse population have made the Yucca Mountain area a viable candidate during the search for a nuclear waste disposal site. Yucca Mountain, however, lies within the southern Great Basin, a region of known contemporary tectonism and young volcanic activity, and the characterization of tectonism and volcanism remains as a fundamental problem for the Yucca Mountain site. The United States Geological Survey has been conducting extensive studies to evaluate the geologic setting of Yucca Mountain, as well as the timing and rates of tectonic and volcanic activity in the region. A workshop was convened by the Geologic Survey in Denver, Colorado, on August 19, 20, and 21, 1985, to review the scientific progress and direction of these studies. Considerable debate resulted. This collection of papers represents the results of some of the studies presented at the workshop, but by no means covers all of the scientific results and viewpoints presented. Rather, the volume is meant to serve as a progress report on some of the studies within the Geological Survey`s continuing research program toward characterizing the tectonic framework of Yucca Mountain. Individual papers were processed separately for the data base.
International Nuclear Information System (INIS)
Dvorzhak, Alla; Mora, Juan C.; Robles, Beatriz
2016-01-01
Potential exposures are those that may occur as a result of unanticipated operational performance or accidents. Potential exposure situations are probabilistic in nature because they depend on uncertain events such as equipment failure, operator errors or external initiators beyond the control of the operator. Consequently, there may exist a range of possible radiological impacts that need to be considered. In this paper a Level 3 Probabilistic Safety Assessment (PSA) for a hypothetical scenario relevant to Innovative Nuclear Energy Systems (INS) was conducted using computer code MACCS (MELCOR Accident Consequence Code Systems). The acceptability of an INS was analyzed taking into account the general requirement that relocation or evacuation measures must not be necessary beyond the site boundary. In addition, deterministic modeling of the accident consequences for the critical meteorological conditions was carried out using the JRODOS decision support system (Real-time On-line Decision Support system for off-site emergency management in Europe). The approach used for dose and risk assessment from potential exposure of accidental releases and their comparison with acceptance criteria are presented. The methodology described can be used as input to the licensing procedure and engineering design considerations to help satisfy relevant health and environmental impact criteria for fission or fusion nuclear installations. - Highlights: • PSA Level-3 based on WinMACCS code is carried out for accidental release. • Family curves of percentiles for radiation exposure doses are constructed. • Risk indicators for potential exposure are defined. • Using of risk acceptance curve criteria is proposed for decision making process.
Yale, Paul B
2012-01-01
This book is an introduction to the geometry of Euclidean, affine, and projective spaces with special emphasis on the important groups of symmetries of these spaces. The two major objectives of the text are to introduce the main ideas of affine and projective spaces and to develop facility in handling transformations and groups of transformations. Since there are many good texts on affine and projective planes, the author has concentrated on the n-dimensional cases.Designed to be used in advanced undergraduate mathematics or physics courses, the book focuses on ""practical geometry,"" emphasi
Symmetries leading to inflation
International Nuclear Information System (INIS)
Aguirregabiria, Juan M.; Lazkoz, Ruth; Chimento, Luis P.; Jakubi, Alejandro S.
2003-01-01
We present here the general transformation that leaves unchanged the form of the field equations for perfect fluid Friedmann-Robertson-Walker and Bianchi type V cosmologies. The symmetries found can be used as algorithms for generating new cosmological models from existing ones. A particular case of the general transformation is used to illustrate the crucial role played by the number of scalar fields in the occurrence of inflation. Related to this, we also study the existence and stability of Bianchi type V power law solutions
Farmer, David W
1995-01-01
In most mathematics textbooks, the most exciting part of mathematics-the process of invention and discovery-is completely hidden from the reader. The aim of Groups and Symmetry is to change all that. By means of a series of carefully selected tasks, this book leads readers to discover some real mathematics. There are no formulas to memorize; no procedures to follow. The book is a guide: Its job is to start you in the right direction and to bring you back if you stray too far. Discovery is left to you. Suitable for a one-semester course at the beginning undergraduate level, there are no prerequ
Nuclear theory progress report
International Nuclear Information System (INIS)
1991-01-01
This report discusses research performed at University of Washington in nuclear theory. Some of the topics discussed are: nuclear astrophysics; symmetry; time reversal invariance; quark matter; superallowed beta decay; exclusive reactions; nuclear probes; soliton model; relativistic heavy ion collisions; supernova explosions; neutrino processes in dense matter; field theories; weak interaction physics; and nuclear structure
Applications of chiral symmetry
International Nuclear Information System (INIS)
Pisarski, R.D.
1995-03-01
The author discusses several topics in the applications of chiral symmetry at nonzero temperature. First, where does the rho go? The answer: up. The restoration of chiral symmetry at a temperature T χ implies that the ρ and a 1 vector mesons are degenerate in mass. In a gauged linear sigma model the ρ mass increases with temperature, m ρ (T χ ) > m ρ (0). The author conjectures that at T χ the thermal ρ - a 1 , peak is relatively high, at about ∼1 GeV, with a width approximately that at zero temperature (up to standard kinematic factors). The ω meson also increases in mass, nearly degenerate with the ρ, but its width grows dramatically with temperature, increasing to at least ∼100 MeV by T χ . The author also stresses how utterly remarkable the principle of vector meson dominance is, when viewed from the modern perspective of the renormalization group. Secondly, he discusses the possible appearance of disoriented chiral condensates from open-quotes quenchedclose quotes heavy ion collisions. It appears difficult to obtain large domains of disoriented chiral condensates in the standard two flavor model. This leads to the last topic, which is the phase diagram for QCD with three flavors, and its proximity to the chiral critical point. QCD may be very near this chiral critical point, and one might thereby generated large domains of disoriented chiral condensates
Directory of Open Access Journals (Sweden)
Nazife O. Koca
2016-12-01
Full Text Available We describe an extension of the pyritohedral symmetry in 3D to 4-dimensional Euclidean space and construct the group elements of the 4D pyritohedral group of order 576 in terms of quaternions. It turns out that it is a maximal subgroup of both the rank-4 Coxeter groups W (F4 and W (H4, implying that it is a group relevant to the crystallographic as well as quasicrystallographic structures in 4-dimensions. We derive the vertices of the 24 pseudoicosahedra, 24 tetrahedra and the 96 triangular pyramids forming the facets of the pseudo snub 24-cell. It turns out that the relevant lattice is the root lattice of W (D4. The vertices of the dual polytope of the pseudo snub 24-cell consists of the union of three sets: 24-cell, another 24-cell and a new pseudo snub 24-cell. We also derive a new representation for the symmetry group of the pseudo snub 24-cell and the corresponding vertices of the polytopes.
Bootstrap Dynamical Symmetry Breaking
Directory of Open Access Journals (Sweden)
Wei-Shu Hou
2013-01-01
Full Text Available Despite the emergence of a 125 GeV Higgs-like particle at the LHC, we explore the possibility of dynamical electroweak symmetry breaking by strong Yukawa coupling of very heavy new chiral quarks Q . Taking the 125 GeV object to be a dilaton with suppressed couplings, we note that the Goldstone bosons G exist as longitudinal modes V L of the weak bosons and would couple to Q with Yukawa coupling λ Q . With m Q ≳ 700 GeV from LHC, the strong λ Q ≳ 4 could lead to deeply bound Q Q ¯ states. We postulate that the leading “collapsed state,” the color-singlet (heavy isotriplet, pseudoscalar Q Q ¯ meson π 1 , is G itself, and a gap equation without Higgs is constructed. Dynamical symmetry breaking is affected via strong λ Q , generating m Q while self-consistently justifying treating G as massless in the loop, hence, “bootstrap,” Solving such a gap equation, we find that m Q should be several TeV, or λ Q ≳ 4 π , and would become much heavier if there is a light Higgs boson. For such heavy chiral quarks, we find analogy with the π − N system, by which we conjecture the possible annihilation phenomena of Q Q ¯ → n V L with high multiplicity, the search of which might be aided by Yukawa-bound Q Q ¯ resonances.
Wilczek, Frank
2004-01-01
Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world (8 pages) Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world. The discrepancy is ascribed to a pervasive symmetry-breaking field, which fills all space uniformly, rendering the Universe a sort of exotic superconductor. So far, the evidence for these bold ideas is indirect. But soon the theory will undergo a critical test depending on whether the quanta of this symmetry-breaking field, the so-called Higgs particles, are produced at the Large Hadron Collider (due to begin operation in 2007).
Energy Technology Data Exchange (ETDEWEB)
Paolucci, D.A.; Trapold, A.C.; Lyding, J.F.
1983-05-02
This report presents the results of an evaluation of potential approaches to arms control limitations of intermediate-range nuclear forces (INF). This analysis focused on U.S./NATO and Soviet land-based nuclear weapon systems deployed or scheduled for deployment in the European area. The weapon systems were the longer range missiles (1,000 to 5,000 km), shorter range missiles (500 to 925 km), and nuclear capable aircraft. An analysis was conducted to evaluate the relative effectiveness of the U.S./NATO and Soviet weapon systems and forces. In conjunction with this analysis nuclear threat target lists were developed in order to evaluate the relative capabilities and limitations of these forces to attack high priority nuclear threat targets. A series of potential alternative approaches to limitations and reductions of these nuclear weapon systems and forces were developed and evaluated. Particular attention was paid to U.S. and Soviet draft proposals and negotiating positions which have been developed during the ongoing INF negotiations. In addition to the analysis of these weapon systems to attack the nuclear threat target lists, a number of measures was selected to provide a basis for a comparison and evaluation of the alternative limitations and reductions of missile systems. These measures were number of launchers and warheads, missile range, equivalent megatons (EMT), counter military potential (CMP), hard target kill capability, and capability against airfields.
GC Side Event: Africa's Energy Needs and the Potential Role of Nuclear Power. Presentations
International Nuclear Information System (INIS)
2015-01-01
Energy is central to development, and energy availability, accessibility and affordability are central challenges for most African countries. Due to rapidly growing energy demand, the need for socioeconomic development, persistent concerns over climate change and environmental impacts and dependence on imported supplies of fossil fuels, African Member States are looking into possible options to secure sustainable energy supplies, including nuclear energy. The IAEA assists those countries in assessing the nuclear power option and building the necessary infrastructure for a safe, secure and sustainable nuclear power programme. This year, the IAEA is conducting Integrated Nuclear Infrastructure Review (INIR) missions to three African countries (Nigeria, Kenya and Morocco) considering introducing nuclear power. The side event presents recent updates from Africa on the potential role of nuclear power, including the IAEA Third Regional Conference on Energy and Nuclear Power in Africa, held in Mombasa, Kenya, in April 2015, an initiative to launch a new African network for enhancing nuclear power programme development, and others. The event reports on recent developments in several African Member States considering, embarking on, or expanding national nuclear power programmes.
International Nuclear Information System (INIS)
Wairagu, Peninah M.; Park, Kwang Hwa; Kim, Jihye; Choi, Jong-Whan; Kim, Hyun-Won; Yeh, Byung-Il; Jung, Soon-Hee; Yong, Suk-Joong; Jeong, Yangsik
2014-01-01
Highlights: • The 48 NR genes and 48 biological anti-cancer targets are profiled in paired-cells. • Growth inhibition by NR ligands or TKIs is target receptor level-dependent. • T0901317 with gefitinib/PHA665752 shows additive growth inhibition in lung cells. - Abstract: Cancer heterogeneity is a big hurdle in achieving complete cancer treatment, which has led to the emergence of combinational therapy. In this study, we investigated the potential use of nuclear receptor (NR) ligands for combinational therapy with other anti-cancer drugs. We first profiled all 48 NRs and 48 biological anti-cancer targets in four pairs of lung cell lines, where each pair was obtained from the same patient. Two sets of cell lines were normal and the corresponding tumor cell lines while the other two sets consisted of primary versus metastatic tumor cell lines. Analysis of the expression profile revealed 11 NRs and 15 cancer targets from the two pairs of normal versus tumor cell lines, and 9 NRs and 9 cancer targets from the primary versus metastatic tumor cell lines had distinct expression patterns in each category. Finally, the evaluation of nuclear receptor ligand T0901317 for liver X receptor (LXR) demonstrated its combined therapeutic potential with tyrosine kinase inhibitors. The combined treatment of cMET inhibitor PHA665752 or EGFR inhibitor gefitinib with T0901317 showed additive growth inhibition in both H2073 and H1993 cells. Mechanistically, the combined treatment suppressed cell cycle progression by inhibiting cyclinD1 and cyclinB expression. Taken together, this study provides insight into the potential use of NR ligands in combined therapeutics with other biological anti-cancer drugs
Effect of deformation and orientation on spin orbit density dependent nuclear potential
Mittal, Rajni; Kumar, Raj; Sharma, Manoj K.
2017-11-01
Role of deformation and orientation is investigated on spin-orbit density dependent part VJ of nuclear potential (VN=VP+VJ) obtained within semi-classical Thomas Fermi approach of Skyrme energy density formalism. Calculations are performed for 24-54Si+30Si reactions, with spherical target 30Si and projectiles 24-54Si having prolate and oblate shapes. The quadrupole deformation β2 is varying within range of 0.023 ≤ β2 ≤0.531 for prolate and -0.242 ≤ β2 ≤ -0.592 for oblate projectiles. The spin-orbit dependent potential gets influenced significantly with inclusion of deformation and orientation effect. The spin-orbit barrier and position gets significantly influenced by both the sign and magnitude of β2-deformation. Si-nuclei with β220. The possible role of spin-orbit potential on barrier characteristics such as barrier height, barrier curvature and on the fusion pocket is also probed. In reference to prolate and oblate systems, the angular dependence of spin-orbit potential is further studied on fusion cross-sections.
Neutrino masses and family symmetry
International Nuclear Information System (INIS)
Grinstein, B.; Preskill, J.; Wise, M.B.
1985-01-01
Neutrino masses in the 100 eV-1 MeV range are permitted if there is a spontaneously broken global family symmetry that allows the heavy neutrinos to decay by Goldstone boson emission with a cosmologically acceptable lifetime. The family symmetry may be either abelian or nonabelian; we present models illustrating both possibilities. If the family symmetry is nonabelian, then the decay tau -> μ + Goldstone boson or tau -> e + Goldstone may have an observable rate. (orig.)
Observation of 54Ni: cross-conjugate symmetry in f7/2 mirror energy differences.
Gadea, A; Lenzi, S M; Lunardi, S; Mărginean, N; Zuker, A P; de Angelis, G; Axiotis, M; Martínez, T; Napoli, D R; Farnea, E; Menegazzo, R; Pavan, P; Ur, C A; Bazzacco, D; Venturelli, R; Kleinheinz, P; Bednarczyk, P; Curien, D; Dorvaux, O; Nyberg, J; Grawe, H; Górska, M; Palacz, M; Lagergren, K; Milechina, L; Ekman, J; Rudolph, D; Andreoiu, C; Bentley, M A; Gelletly, W; Rubio, B; Algora, A; Nacher, E; Caballero, L; Trotta, M; Moszyński, M
2006-10-13
Gamma decays from excited states up to Jpi=6+ in the N=Z-2 nucleus 54Ni have been identified for the first time. Level energies are compared with those of the isobars 54Co and 54Fe and of the cross-conjugate nuclei of mass A=42. The good but puzzling f7/ cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials.
Studies on nuclear fusion energy potential based on a long-term world energy and environment model
International Nuclear Information System (INIS)
Tokimatsu, K.; Fujino, J.; Asaoka, Y.
2001-01-01
This study investigates introduction conditions and potential of nuclear fusion energy as energy supply and CO 2 mitigation technologies in the 21st century. Time horizon of the 21st century, 10 regionally allocated world energy/environment model (Linearized Dynamic New Earth 21) is used for this study. Following nuclear fusion technological data are taken into consideration: cost of electricity (COE) in nuclear fusion introduction year, annual COE reduction rates, regional introduction year, and maximum regional plant capacity constraints by maximum plant construction speed. We made simulation under a constraint of atmospheric CO 2 concentration of 550 parts per million by volume (ppmv) targeted at year 2100, assuming that sequestration technologies and unknown innovative technologies for CO 2 reduction are available. The results indicate that under the 550ppm scenario with nuclear fusion within maximum construction speed, 66mill/kWh is required for introducing nuclear fusion in 2050, 92 mill/kWh in 2060, and 106 mill/kWh in 2070. Therefore, tokamak type nuclear fusion reactors of present several reactor cost estimates are expected to be introduced between 2060 and 2070, and electricity generation fraction by nuclear fusion will go around 20% in 2100 if nuclear fusion energy growth is limited only by the maximum construction speed. CO 2 reduction by nuclear fusion introduced in 2050 from business-as-usual (BAU) scenario without nuclear fusion is about 20% of total reduction amount in 2100. In conclusion, nuclear fusion energy is revealed to be one of the candidates of energy supply technologies and CO 2 mitigation technologies. Cost competitiveness and removal of capacity constraint factors are desired for use of nuclear fusion energy in a large scale. (author)
Evaluation of a seafloor nuclear power supply and its potential applications. Final report
International Nuclear Information System (INIS)
1977-01-01
The seafloor nuclear power supply (SNPS) concept has been proposed by Atomics International (AI) and Lockheed Petroleum Services, Ltd. (LPS) as a source of electrical energy for subsea pumping of petroleum products. It consists of a small nuclear reactor, moderated by zirconium hydride (ZrH) and cooled by liquid metal (NaK), which drives a 3-MW turbine/generator system using toluene as the working fluid. Arthur D. Little, Inc., was selected to assess the technical and economic feasibility of a SNPS, and to determine if potential applications for a SNPS might exist in offshore-oil-field development schemes where conventional power supplies could not be used. It was determined that the concept is technically feasible, with regard to the nuclear, marine, electrical, and petroleum engineering aspects. However, its initial cost of $14 million and operating expenses of $900,000 per year are considerably more in each case than the costs of conventional alternative power supplies. For the type of field development proposed as an example by LPS, a combination of gas turbines and dc cables would cost about $8 million. Fuel in the form of gas from the wells would be available at near-zero cost in almost all cases of field development, so that operating expenses would be minimal. Other power supply and cable systems were investigated, up to lengths of 200 miles. Alternating-current systems are preferred at distances less than 20 miles; direct current is more economical at greater distances. No set of circumstances was found in which oil field development is likely to occur and for which the SNPS offers uniquely attractive capabilities
The conservation of orbital symmetry
Woodward, R B
2013-01-01
The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain-or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book ope
An introduction to Yangian symmetries
International Nuclear Information System (INIS)
Bernard, D.
1992-01-01
Some aspects of the quantum Yangians as symmetry algebras of two-dimensional quantum field theories are reviewed. They include two main issues: the first is the classical Heisenberg model, covering non-Abelian symmetries, generators of the symmetries and the semi-classical Yangians, an alternative presentation of the semi-classical Yangians, digression on Poisson-Lie groups. The second is the quantum Heisenberg chain, covering non-Abelian symmetries and the quantum Yangians, the transfer matrix and an alternative presentation of the Yangians, digression on the double Yangians. (K.A.) 15 refs
Leptogenesis and residual CP symmetry
International Nuclear Information System (INIS)
Chen, Peng; Ding, Gui-Jun; King, Stephen F.
2016-01-01
We discuss flavour dependent leptogenesis in the framework of lepton flavour models based on discrete flavour and CP symmetries applied to the type-I seesaw model. Working in the flavour basis, we analyse the case of two general residual CP symmetries in the neutrino sector, which corresponds to all possible semi-direct models based on a preserved Z 2 in the neutrino sector, together with a CP symmetry, which constrains the PMNS matrix up to a single free parameter which may be fixed by the reactor angle. We systematically study and classify this case for all possible residual CP symmetries, and show that the R-matrix is tightly constrained up to a single free parameter, with only certain forms being consistent with successful leptogenesis, leading to possible connections between leptogenesis and PMNS parameters. The formalism is completely general in the sense that the two residual CP symmetries could result from any high energy discrete flavour theory which respects any CP symmetry. As a simple example, we apply the formalism to a high energy S 4 flavour symmetry with a generalized CP symmetry, broken to two residual CP symmetries in the neutrino sector, recovering familiar results for PMNS predictions, together with new results for flavour dependent leptogenesis.
Quarks, baryons and chiral symmetry
Hosaka, Atsushi
2001-01-01
This book describes baryon models constructed from quarks, mesons and chiral symmetry. The role of chiral symmetry and of quark model structure with SU(6) spin-flavor symmetry are discussed in detail, starting from a pedagogic introduction. Emphasis is placed on symmetry aspects of the theories. As an application, the chiral bag model is studied for nucleon structure, where important methods of theoretical physics, mostly related to the semiclassical approach for a system of strong interactions, are demonstrated. The text is more practical than formal; tools and ideas are explained in detail w
Extensive test of an SU(3)-based partial dynamical symmetry
International Nuclear Information System (INIS)
Casten, R F
2014-01-01
The concept of symmetries pervades much of our understanding of nature. In nuclear structure, the IBA embodies a framework with three dynamical symmetries U(5), O(6) and SU(3). Of course, most nuclei break these symmetries. Leviatan has discussed a concept of Partial Dynamical Symmetry (PDS) in which the states of the ground and gamma bands, only, are exactly described by SU(3) while all others are not. With an E2 operator which is not a generator of SU(3), this PDS gives a parameter-free description of γ to ground band relative B(E2) values in 168 Er that is virtually identical to the best collective model (IBA) calculations with 2-3 parameters. We have carried out the first extensive study of this PDS, in 47 rare earth nuclei. Overall, the PDS works very well, and the deviations from the data are usually understandable in terms of specific kinds of mixing.
Extensive Test of an SU(3)-based Partial Dynamical Symmetry
Casten, R. F.
2014-09-01
The concept of symmetries pervades much of our understanding of nature. In nuclear structure, the IBA embodies a framework with three dynamical symmetries U(5), O(6) and SU(3). Of course, most nuclei break these symmetries. Leviatan has discussed a concept of Partial Dynamical Symmetry (PDS) in which the states of the ground and gamma bands, only, are exactly described by SU(3) while all others are not. With an E2 operator which is not a generator of SU(3), this PDS gives a parameter-free description of γ to ground band relative B(E2) values in 168Er that is virtually identical to the best collective model (IBA) calculations with 2-3 parameters. We have carried out the first extensive study of this PDS, in 47 rare earth nuclei. Overall, the PDS works very well, and the deviations from the data are usually understandable in terms of specific kinds of mixing.
Potential threat to licensed nuclear activities from insiders (insider study). Technical report
International Nuclear Information System (INIS)
Mullen, S.A.; Davidson, J.J.; Jones, H.B. Jr.
1980-07-01
The Insider Study was undertaken by NRC staff at the request of the Commission. Its objectives were to: (1) determine the characteristics of potential insider adversaries to licensed nuclear activities; (2) examine security system vulnerabilities to insider adversaries; and (3) assess the effectiveness of techniques used to detect or prevent insider malevolence. The study analyzes insider characteristics as revealed in incidents of theft or sabotage that occurred in the nuclear industry, analogous industries, government agencies, and the military. Adversary characteristics are grouped into four categories: position-related, behavioral, resource and operational. It also analyzes (1) the five security vulnerabilities that most frequently accounted for the success of the insider crimes in the data base; (2) the 11 means by which insider crimes were most often detected; and (3) four major and six lesser methods aimed at preventing insider malevolence. In addition to case history information, the study contains data derived from non-NRC studies and from interviews with over 100 security experts in industry, government (federal and state), and law enforcement
Potentially of using vertical and three dimensional isolation systems in nuclear structures
Energy Technology Data Exchange (ETDEWEB)
Zhou, Zhiuang [Research Institute of Structural Engineering and Disaster Reduction, Tongji University, Shanghai (China); Wong, Jenna [Lawrence Berkeley National Laboratories, Berkeley (United States); Mahin, Stephen [University of California, Berkeley (United States)
2016-10-15
Although the horizontal component of an earthquake response can be significantly reduced through the use of conventional seismic isolators, the vertical component of excitation is still transmitted directly into the structure. Records from instrumented structures, and some recent tests and analyses have actually seen increases in vertical responses in base isolated structures under the combined effects of horizontal and vertical ground motions. This issue becomes a great concern to facilities such as a Nuclear Power Plants (NPP), with specialized equipment and machinery that is not only expensive, but critical to safe operation. As such, there is considerable interest worldwide in vertical and three-dimensional (3D) isolation systems. This paper examines several vertical and 3D isolation systems that have been proposed and their potential application to modern nuclear facilities. In particular, a series of case study analyses of a modern NPP model are performed to examine the benefits and challenges associated with 3D isolation compared with horizontal isolation. It was found that compared with the general horizontal isolators, isolators that have vertical frequencies of no more than 3 Hz can effectively reduce the vertical in-structure responses for the studied NPP model. Among the studied cases, the case that has a vertical isolation frequency of 3 Hz is the one that can keep the horizontal period of the isolators as the first period while having the most flexible vertical isolator properties. When the vertical frequency of isolators reduces to 1 Hz, the rocking effect is obvious and rocking restraining devices are necessary.
Wang, Dongqing; Liu, Yu; Jiang, Jin; Pang, Wei; Lau, Woon Ming; Mei, Jun
2017-05-01
In the design of nuclear power plants, various natural circulation passive cooling systems are considered to remove residual heat from the reactor core in the event of a power loss and maintain the plant's safety. These passive systems rely on gravity differences of fluids, resulting from density differentials, rather than using an external power-driven system. Unfortunately, a major drawback of such systems is their weak driving force, which can negatively impact safety. In such systems, there is a temperature difference between the heat source and the heat sink, which potentially offers a natural platform for thermoelectric generator (TEG) applications. While a previous study designed and analyzed a TEG-based passive core cooling system, this paper considers TEG applications in other passive cooling systems of nuclear power plants, after which the concept of a TEG-based passive cooling system is proposed. In such a system, electricity is produced using the system's temperature differences through the TEG, and this electricity is used to further enhance the cooling process.
Nonlocal symmetries and nonlocal conservation laws of Maxwell's equations
International Nuclear Information System (INIS)
Anco, S.C.; Bluman, G.
1997-01-01
Nonlocal symmetries are obtained for Maxwell's equations in three space-time dimensions through the use of two potential systems involving scalar and vector potentials for the electromagnetic field. Corresponding nonlocal conservation laws are derived from these symmetries. The conservation laws yield nine functionally independent constants of motion which cannot be expressed in terms of the constants of motion arising from local conservation laws for space-time symmetries. These nine constants of motion represent additional conserved quantities for the electromagnetic field in three space endash time dimensions. copyright 1997 American Institute of Physics
International Court of Justice on Potential Transboundary Damage and its Consequences in Nuclear Law
International Nuclear Information System (INIS)
Cletienne, M.
2010-01-01
On 4 May 2006, Argentina filed in the International Court of Justice ('ICJ') an application instituting proceedings against Uruguay. Argentina claimed that Uruguay, by authorizing the construction of a pulp mill (the 'CMB mill') and the construction and commissioning of another pulp mill (the 'Orion mill'), breached its obligations under the 1975 Statute of the River Uruguay, a treaty between Argentina and Uruguay, notably the obligation to take all necessary measures for the optimum and rational utilisation of the River Uruguay. On 20 April 2010,1 the court rendered its decision settling this environmental dispute between Argentina and Uruguay. This paper will first summarize the judgement and then consider the main contribution of this decision to international environmental law, e.g. the recognition of an international customary rule to conduct an environmental impact assessment. Finally, the potential consequences of the decision in nuclear law will be addressed in the last part
International Nuclear Information System (INIS)
Martin, C.D.; Chandler, N.A.
1996-12-01
A seismic event which causes damage to an underground opening is called a rockburst. Practical experience indicates that these damaging seismic events are associated with deep mines where extraction ratios are greater than 0.6. For the arrangement being considered by AECL for nuclear fuel waste disposal vaults, extraction ratios, for the room and pillar design, will be less than 0.3. At this extraction ratio the stress magnitudes will not be sufficient to induce seismic events that can damage the underground openings. Documented world-wide experience shows that unless the underground opening is very close to the source of a naturally occurring seismic event, such as an earthquake, the opening will also not experience any significant damage. Backfilling a disposal vault will improve its resistance to earthquake damage. Backfilling a disposal vault will also reduce the total convergence of the openings caused by thermal loads and hence minimize the potential for thermally-induced seismic events. (author)
The Economic Potential of Nuclear-Renewable Hybrid Energy Systems Producing Hydrogen
Energy Technology Data Exchange (ETDEWEB)
Ruth, Mark [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cutler, Dylan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Flores-Espino, Francisco [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stark, Greg [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2017-04-01
This report is one in a series of reports that Idaho National Laboratory and the Joint Institute for Strategic Energy Analysis are publishing that address the technical and economic aspects of nuclear-renewable hybrid energy systems (N-R HESs). This report discusses an analysis of the economic potential of a tightly coupled N-R HES that produces electricity and hydrogen. Both low and high temperature electrolysis options are considered in the analysis. Low-temperature electrolysis requires only electricity to convert water to hydrogen. High temperature electrolysis requires less electricity because it uses both electricity and heat to provide the energy necessary to electrolyze water. The study finds that, to be profitable, the examined high-temperature electrosis and low-temperature electrosis N-R HES configurations that produce hydrogen require higher electricity prices, more electricity price volatility, higher natural gas prices, or higher capacity payments than the reference case values of these parameters considered in this analysis.
The time-reversal- and parity-violating nuclear potential in chiral effective theory
Energy Technology Data Exchange (ETDEWEB)
Maekawa, C.M. [Instituto de Matematica, Estatistica e Fisica, Universidade Federal do Rio Grande, Campus Carreiros, PO Box 474, 96201-900 Rio Grande, RS (Brazil); Mereghetti, E., E-mail: emanuele@physics.arizona.edu [Department of Physics, University of Arizona, Tucson, AZ 85721 (United States); Vries, J. de [KVI, Theory Group, University of Groningen, 9747 AA Groningen (Netherlands); Kolck, U. van [Department of Physics, University of Arizona, Tucson, AZ 85721 (United States)
2011-12-15
We derive the parity- and time-reversal-violating nuclear interactions stemming from the QCD {theta}{sup Macron} term and quark/gluon operators of effective dimension 6: quark electric dipole moments, quark and gluon chromo-electric dipole moments, and two four-quark operators. We work in the framework of two-flavor chiral perturbation theory, where a systematic expansion is possible. The different chiral-transformation properties of the sources of time-reversal violation lead to different hadronic interactions. For all sources considered the leading-order potential involves known one-pion exchange, but its specific form and the relative importance of short-range interactions depend on the source. For the {theta}{sup Macron} term, the leading potential is solely given by one-pion exchange, which does not contribute to the deuteron electric dipole moment. In subleading order, a new two-pion-exchange potential is obtained. Its short-range component is indistinguishable from one of two undetermined contact interactions that appear at the same order and represent effects of heavier mesons and other short-range QCD dynamics. One-pion-exchange corrections at this order are discussed as well.
Parameterization of Nuclear Hulthén Potential for Nucleus-Nucleus Elastic Scattering
Bhoi, J.; Upadhyay, R.; Laha, U.
2018-02-01
In contrast to Gaussian or Woods-Saxon potential a two-term four parameter nuclear Hulthén type interaction is considered to describe the α-α, α-3He and α-3H systems. By exploiting the phase function method, scattering phase shifts are computed up to ELab = 100 MeV for the α-α system and ELab = 15 MeV for α-3He and α-3H systems. The S-wave phase shift δ 0 for the α-α system tends to 2π and δ 3/2 ‑ for the α-3He system tends to π, in the limit of zero energy. Reasonable agreements in phase shifts with the standard data are obtained with this simple potential model except for the 5/2‑ states of α-3He and α-3H systems. With an additional energy-dependent correction factor to our potential, a good agreement with experimental data is obtained for 5/2‑ states. We have also compared our results with the convenient Born approximations.
Koshibu, K; Gräff, J; Mansuy, I M
2011-01-26
Complex brain diseases and neurological disorders in human generally result from the disturbance of multiple genes and signaling pathways. These disturbances may derive from mutations, deletions, translocations or rearrangements of specific gene(s). However, over the past years, it has become clear that such disturbances may also derive from alterations in the epigenome affecting several genes simultaneously. Our work recently demonstrated that epigenetic mechanisms in the adult brain are in part regulated by protein phosphatase 1 (PP1), a protein Ser/Thr phosphatase that negatively regulates hippocampus-dependent long-term memory (LTM) and synaptic plasticity. PP1 is abundant in brain structures involved in emotional processing like the amygdala, it may therefore be involved in the regulation of fear memory, a form of memory related to post-traumatic stress disorder (PTSD) in human. Here, we demonstrate that PP1 is a molecular suppressor of fear memory and synaptic plasticity in the amygdala that can control chromatin remodeling in neurons. We show that the selective inhibition of the nuclear pool of PP1 in amygdala neurons significantly alters posttranslational modifications (PTMs) of histones and the expression of several memory-associated genes. These alterations correlate with enhanced fear memory, and with an increase in long-term potentiation (LTP) that is transcription-dependent. Our results underscore the importance of nuclear PP1 in the amygdala as an epigenetic regulator of emotional memory, and the relevance of protein phosphatases as potential targets for therapeutic treatment of brain disorders like PTSD. © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Matthes, Felix C.; Hermann, Hauke
2009-06-01
The discussions on electricity price effects in case of the plant life extension of German nuclear power plants covers the following topics: (1) Introduction and methodology. (2) Electricity generation in nuclear power plants and electricity price based on an empirical view: electricity generation in nuclear power plants and final consumption price for households and industry in the European Union; electricity generation in nuclear power plants and electricity wholesale price in case of low availability of nuclear power plants in Germany; comparison of electricity wholesale prices in Germany and France. (3) Model considerations in relation to electricity prices and nuclear phase-out. (4) Concluding considerations.
Application of Solar Chimney Concept to Solve Potential Safety Issues of Nuclear Power Plants
International Nuclear Information System (INIS)
Khasawneh, Khalid; PARK, Youn Won
2014-01-01
In this paper two main events and their causes have been investigated and a potential alternative supporting system will be provided. The first event to be addressed is the Station Blackout (SBO) caused by the inherent unreliability of the Emergency Diesel Generators (EDGs) and Alternative AC (AAC) power sources. Different parameters affect The EDG unreliability; for instance, mechanical, operational, maintenance and surveillance. Those parameters will be analyzed and linked to plant safety and Core Damage Frequency (CDF). Also the AACs, the SBO diesel generators, will be studied and their operational requirements similarity with the EDGs will be discussed. The second event to be addressed is the Loss of Ultimate Heat Sink (LUHS) caused by the degradation of heat exchange effectiveness, that is, the poor heat transfer to the Ultimate Heat Sink (UHS). Different causes to such case were observed; intake lines blockages due to ice and foreign biological matters formation and oil spill near the heat sink causing the oil leakage to the heat exchangers tubes. The later cause, oil spill, has been given a special attention here due its potential effects for different nuclear power plants (NPPs) around the world; for example, Finland and the United Arab Emirates (UAE). For the Finnish case, the Finnish nuclear regulator (STUK) took already countermeasures for such scenario by introducing alternative heat sink, cooling towers, for the primary used heat sink, sea water, for one of its nuclear power plants. The abundance of the solar irradiation in the UAE region provides a perfect condition for the implementation of solar power applications. Utilizing this unique characteristic of that region may provide promising alternative and diverse options for solving potential safety related issues of their NPPs. The Solar Chimney Power Plant (SCPP) could be employed to serve as a supporting system to provide emergency power, in the case of SBO, and emergency cooling, in the case of
Determining Symmetry Properties of Gravitational Fields of Terrestrial Group Planets
Directory of Open Access Journals (Sweden)
R.A. Kascheev
2016-09-01
Full Text Available Numerous models of gravity fields of the Solar system bodies have been constructed recently owing to successful space missions. These models are sets of harmonic coefficients of gravity potential expansion in series of spherical functions, which is Laplace series. The sets of coefficients are different in quantity of numerical parameters, sources and composition of the initial observational data, methods to obtain and process them, and, consequently, in a variety of properties and accuracy characteristics. For this reason, the task of comparison of different models of celestial bodies considered in the paper is of interest and relevant. The main purpose of this study is comparison of the models of gravitational potential of the Earth, Moon, Mars, and Venus with the quantitative criteria of different types of symmetries developed by us. It is assumed that some particular symmetry of the density distribution function of the planetary body causes similar symmetry of its gravitational potential. The symmetry of gravitational potential, in its turn, imposes additional conditions (restrictions, which must be satisfied by the harmonic coefficients. The paper deals with seven main types of symmetries: central, axial, two symmetries specular relative to the equatorial planes and prime meridian, as well as three rotational symmetries (at π angle around the coordinate system axes. According to the results of calculations carried out for the Earth, Moon, Mars, and Venus, the values of the criteria vary considerably for different types of symmetries and for different planets. It means that the specific value of each criterion corresponding to a particular celestial body is indicative of the properties and internal structure characteristics of the latter and, therefore, it can be used as a tool for comparative planetology. On the basis of the performed calculations, it is possible to distinguish two groups of celestial bodies having similar properties of
Nuclear Physics Laboratory: Annual report
International Nuclear Information System (INIS)
1987-05-01
Topics covered in this annual report are: astrophysics and cosmology, giant resonances in excited nuclei, heavy ions, fundamental symmetries, nuclear reactions, accelerator mass spectrometry, accelerators and ion sources, nuclear instrumentation, computer systems and the booster linac project
Characterization of Partial Intrinsic Symmetries
Shehu, Aurela; Brunton, Alan; Wuhrer, Stefanie; Wand, Michael
2014-01-01
We present a mathematical framework and algorithm for characterizing and extracting partial intrinsic symmetries of surfaces, which is a fundamental building block for many modern geometry processing algorithms. Our goal is to compute all “significant” symmetry information of the shape, which we
Symmetry preservation during radiation damage
International Nuclear Information System (INIS)
Bhat, S.V.; Abdel-Gawad, M.M.H.
1991-01-01
An examination of radiation-damage processes consequent to high-energy irradiation in certain ammonium salts studied using ESR of free radicals together with the structural information available from neutron diffraction studies shows that, other factors being equal/nearly equal, symmetry-related bonds are preserved in preference to those unrelated to one another by any symmetry. (author). 23 refs., 3 tabs
Singlets of fermionic gauge symmetries
Bergshoeff, E.A.; Kallosh, R.E.; Rahmanov, M.A.
1989-01-01
We investigate under which conditions singlets of fermionic gauge symmetries which are "square roots of gravity" can exist. Their existence is non-trivial because there are no fields neutral in gravity. We tabulate several examples of singlets of global and local supersymmetry and Îº-symmetry and
Symmetry guide to ferroaxial transitions
Czech Academy of Sciences Publication Activity Database
Hlinka, Jiří; Přívratská, J.; Ondrejkovič, Petr; Janovec, Václav
2016-01-01
Roč. 116, č. 17 (2016), 1-6, č. článku 177602. ISSN 0031-9007 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : symmetry * symmetry breaking * ferroaxial Transitions * property tensors * Aizu species Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 8.462, year: 2016
Givental Graphs and Inversion Symmetry
Dunin-Barkovskiy, P.; Shadrin, S.; Spitz, L.
2013-01-01
Inversion symmetry is a very non-trivial discrete symmetry of Frobenius manifolds. It was obtained by Dubrovin from one of the elementary Schlesinger transformations of a special ODE associated to a Frobenius manifold. In this paper, we review the Givental group action on Frobenius manifolds in
Collective states and crossing symmetry
International Nuclear Information System (INIS)
Heiss, W.D.
1977-01-01
Collective states are usually described in simple terms but with the use of effective interactions which are supposed to contain more or less complicated contributions. The significance of crossing symmetry is discussed in this connection. Formal problems encountered in the attempts to implement crossing symmetry are pointed out
Discrete symmetries in the MSSM
Energy Technology Data Exchange (ETDEWEB)
Schieren, Roland
2010-12-02
The use of discrete symmetries, especially abelian ones, in physics beyond the standard model of particle physics is discussed. A method is developed how a general, abelian, discrete symmetry can be obtained via spontaneous symmetry breaking. In addition, anomalies are treated in the path integral approach with special attention to anomaly cancellation via the Green-Schwarz mechanism. All this is applied to the minimal supersymmetric standard model. A unique Z{sup R}{sub 4} symmetry is discovered which solves the {mu}-problem as well as problems with proton decay and allows to embed the standard model gauge group into a simple group, i.e. the Z{sup R}{sub 4} is compatible with grand unification. Also the flavor problem in the context of minimal flavor violation is addressed. Finally, a string theory model is presented which exhibits the mentioned Z{sup R}{sub 4} symmetry and other desirable features. (orig.)
Symmetries in geology and geophysics.
Turcotte, D L; Newman, W I
1996-12-10
Symmetries have played an important role in a variety of problems in geology and geophysics. A large fraction of studies in mineralogy are devoted to the symmetry properties of crystals. In this paper, however, the emphasis will be on scale-invariant (fractal) symmetries. The earth's topography is an example of both statistically self-similar and self-affine fractals. Landforms are also associated with drainage networks, which are statistical fractal trees. A universal feature of drainage networks and other growth networks is side branching. Deterministic space-filling networks with side-branching symmetries are illustrated. It is shown that naturally occurring drainage networks have symmetries similar to diffusion-limited aggregation clusters.
Axions from chiral family symmetry
International Nuclear Information System (INIS)
Chang, D.; Pal, P.B.; Maryland Univ., College Park; Senjanovic, G.
1985-01-01
We investigate the possibility that family symmetry, Gsub(F), is spontaneously broken chiral global symmetry. We classify the interesting cases when family symmetry can result in an automatic Peccei-Quinn symmetry U(1)sub(PQ) and thus provide a solution to the strong CP problem. The result disfavors having two or four families. For more than four families, U(1)sub(PQ) is in general automatic. In the case of three families, a unique Higgs sector allows U(1)sub(PQ) in the simplest case of Gsub(F)=[SU(3)] 3 . Cosmological consideration also puts strong constraint on the number of families. For Gsub(F)=[SU(N)] 3 cosmology singles out the three-family (N=3) case as a unique solution if there are three light neutrinos. Possible implication of decoupling theorem as applied to family symmetry breaking is also discussed. (orig.)
Shape analysis with subspace symmetries
Berner, Alexander
2011-04-01
We address the problem of partial symmetry detection, i.e., the identification of building blocks a complex shape is composed of. Previous techniques identify parts that relate to each other by simple rigid mappings, similarity transforms, or, more recently, intrinsic isometries. Our approach generalizes the notion of partial symmetries to more general deformations. We introduce subspace symmetries whereby we characterize similarity by requiring the set of symmetric parts to form a low dimensional shape space. We present an algorithm to discover subspace symmetries based on detecting linearly correlated correspondences among graphs of invariant features. We evaluate our technique on various data sets. We show that for models with pronounced surface features, subspace symmetries can be found fully automatically. For complicated cases, a small amount of user input is used to resolve ambiguities. Our technique computes dense correspondences that can subsequently be used in various applications, such as model repair and denoising. © 2010 The Author(s).
Energy Technology Data Exchange (ETDEWEB)
Jing-dong, Yuan
2010-07-01
The Obama administration is putting nuclear disarmament back on the agenda. In a major speech in Prague in April 2009, he envisioned a world free of nuclear weapons and called on nations to work toward that end. Reversing years of setbacks and stagnation, Washington and Moscow agreed on renewing negotiation on extending the START I Treaty last year and concluded the New START treaty in March 2010. The 2010 Nuclear Posture Review indicates a shift in U.S. nuclear doctrine in that Washington pledges not to use nuclear weapons against non-nuclear weapons states that abide by the Nuclear Nonproliferation Treaty. The prospects of nuclear disarmament look much promising as the momentum generated could also exert pressure on the second-tier nuclear-weapon States: Britain, France, and China. Beijing's responses to these developments have been favorable, viewing them as positive contribution to international nuclear disarmament and nonproliferation. In particular China endorses President Obama's call for securing global nuclear materials and safeguarding vulnerable nuclear facilities to prevent nuclear terrorism. However, Chinese perspectives and policies on important international nuclear arms control and disarmament, and on the role of nuclear weapons and nuclear deterrence remain largely declaratory and less specific on its own commitments and participation. Chinese analyses, at the same time, point out the difficulties ahead on the road toward a nuclear weapons free world. Indeed, rhetoric notwithstanding, Beijing continues to modernize its nuclear arsenal to develop a secure and reliable second-strike deterrence capability. This paper takes a careful look at China's perceptions of the role of nuclear weapons in its national security policy and defense posture. This is important because China is perceived to be the only country among the five original nuclear-weapon States that is actually expanding its nuclear arsenal, as indicated by the recent
International Nuclear Information System (INIS)
Jing-dong, Yuan
2010-01-01
The Obama administration is putting nuclear disarmament back on the agenda. In a major speech in Prague in April 2009, he envisioned a world free of nuclear weapons and called on nations to work toward that end. Reversing years of setbacks and stagnation, Washington and Moscow agreed on renewing negotiation on extending the START I Treaty last year and concluded the New START treaty in March 2010. The 2010 Nuclear Posture Review indicates a shift in U.S. nuclear doctrine in that Washington pledges not to use nuclear weapons against non-nuclear weapons states that abide by the Nuclear Nonproliferation Treaty. The prospects of nuclear disarmament look much promising as the momentum generated could also exert pressure on the second-tier nuclear-weapon States: Britain, France, and China. Beijing's responses to these developments have been favorable, viewing them as positive contribution to international nuclear disarmament and nonproliferation. In particular China endorses President Obama's call for securing global nuclear materials and safeguarding vulnerable nuclear facilities to prevent nuclear terrorism. However, Chinese perspectives and policies on important international nuclear arms control and disarmament, and on the role of nuclear weapons and nuclear deterrence remain largely declaratory and less specific on its own commitments and participation. Chinese analyses, at the same time, point out the difficulties ahead on the road toward a nuclear weapons free world. Indeed, rhetoric notwithstanding, Beijing continues to modernize its nuclear arsenal to develop a secure and reliable second-strike deterrence capability. This paper takes a careful look at China's perceptions of the role of nuclear weapons in its national security policy and defense posture. This is important because China is perceived to be the only country among the five original nuclear-weapon States that is actually expanding its nuclear arsenal, as indicated by the recent deployment of the long
Impact of density-dependent symmetry energy and Coulomb ...
Indian Academy of Sciences (India)
2014-03-07
Mar 7, 2014 ... ter in the events of big bang, supernova explosions, and in the interior of neutron stars. Therefore, it becomes possible to understand the thermodynamical properties of strongly interacting matter. In addition to the reaction conditions, the symmetry energy, i.e. the isospin-dependent part of nuclear equation ...
Testing fundamental symmetries using radioactive ion beams at ...
Indian Academy of Sciences (India)
The ISAC Facility at TRIUMF, Canada's national laboratory for particle and nuclear physics, provides rare isotope beams for a diverse research program. In this paper we summarize some recent experimental developments at TRIUMF pertaining to fundamental symmetry tests. These tests use the atomic nucleus as a probe ...
Final Report Fermionic Symmetries and Self consistent Shell Model
International Nuclear Information System (INIS)
Zamick, Larry
2008-01-01
In this final report in the field of theoretical nuclear physics we note important accomplishments.We were confronted with 'anomoulous' magnetic moments by the experimetalists and were able to expain them. We found unexpected partial dynamical symmetries--completely unknown before, and were able to a large extent to expain them. The importance of a self consistent shell model was emphasized.
Interplay between symmetries and residual interactions in rotating nuclei
International Nuclear Information System (INIS)
Cwiok, S.; Kvasil, J.; Nazmitdinov, R.G.
1990-01-01
Using the space rotation and translation invariance of the nuclear Hamiltonian, the residual interactions for a rotating nucleus are constructed. The connection is found between the Goldstone modes of motion (spurious states) and the symmetries of equations of motion in Random Phase Approximation for states near the yrast line. (author). 18 figs
PC based controlled potential coulometric titrator for quantitative analysis of nuclear materials
International Nuclear Information System (INIS)
Manna, A.; Moorthy, A.D.; Bhogale, R.G.
2001-01-01
With increased requirements for process control and accountability of nuclear materials in plutonium reprocessing plants, the PC based controlled potential coulometric titrator was developed which has the capability of automatic quantitative analysis of the samples. The instruments based on electromechanical methods, incorporates an electronic potentiostat, a digital coulometer with wide dynamic range and a PC with a control interface card. The potentiostat is required to control the potential at the working electrode surface as per predetermined controlled voltage with respect to a reference electrode under wide variations in the conductivity and double layer capacitance of the electrochemical cell. The digital coulometer precisely measures the amount of electronic charge taking part in the electrochemical reactions of interest. The software has the facility to carry out three different types of analysis, i.e., primary coulometry, secondary coulometry and coulogram curve tracing. Due to complete analysis of the samples under program control, the human related errors are minimized and a better precision in the results are obtained. It has been possible to obtain an overall precession of better than +/- 0.3% in the determination of plutonium using the instrument. (author)
International Nuclear Information System (INIS)
Younker, J.L.; Wilson, W.E.; Sinnock, S.
1986-01-01
In support of the US Department of Energy Nevada Nuclear Waste Storage Investigations Project, ground-water travel times were calculated for flow paths in both the saturated and unsaturated zones at Yucca Mountain, a potential site for a high-level radioactive waste repository in southern Nevada. The calculations were made through a combined effort by Science Applications International Corporation, Sandia National Laboratories, and the US Geological Survey. Travel times in the unsaturated zone were estimated by dividing the flow path length by the ground-water velocity, where velocities were obtained by dividing the vertical flux by the effective porosity of the rock types along assumed vertical flow paths. Saturated zone velocities were obtained by dividing the product of the bulk hydraulic conductivity and hydraulic gradient by the effective porosity. Total travel time over an EPA-established 5-km flow path was then calculated to be the sum of the travel times in the two parts of the flow path. Estimates of ground water fluxes and travel times are critical for evaluating the favorability of the Yucca Mountain site because they provide the basis for estimating the potential for radionuclides to reach the accessible environment within certain time limits
SMBH accretion and mergers: removing the symmetries
International Nuclear Information System (INIS)
King, Andrew; Nixon, Chris
2013-01-01
We review recent progress in studying accretion flows on to supermassive black holes (SMBH). Much of this removes earlier assumptions of symmetry and regularity, such as aligned and prograde disc rotation. This allows a much richer variety of effects, often because cancellation of angular momentum allows rapid infall. Potential applications include lower SMBH spins allowing faster mass growth and suppressing gravitational-wave reaction recoil in mergers, gas-assisted SMBH mergers, and near-dynamical accretion in galaxy centres. (paper)
Cozma, M. D.
2017-01-01
The charged pion multiplicity ratio in intermediate-energy heavy-ion collisions, a probe of the density dependence of symmetry energy above the saturation point, has been proven in a previous study to be extremely sensitive to the strength of the isovector Δ (1232 ) potential in nuclear matter. As there is no knowledge, either from theory or experiment, about the magnitude of this quantity, the extraction of constraints on the slope of the symmetry energy at saturation by using exclusively the mentioned observable is hindered at present. It is shown that, by including the ratio of average pT of charged pions / in the list of fitted observables, the noted problem can be circumvented. A realistic description of this observable requires accounting for the interaction of pions with the dense nuclear matter environment by the incorporation of the so-called S -wave and P -wave pion optical potentials. This is performed within the framework of a quantum molecular dynamics transport model that enforces the conservation of the total energy of the system. It is shown that constraints on the slope of the symmetry energy at saturation density and the strength of the Δ (1232) potential can be simultaneously extracted. A symmetry energy with a value of the slope parameter L >50 MeV is favored, at 1 σ confidence level, from a comparison with published FOPI experimental data. A precise constraint will require experimental data more accurate than presently available, particularly for the charged pion multiplicity ratio, and better knowledge of the density and momentum dependence of the pion potential for the whole range of these two variables probed in intermediate-energy heavy-ion collisions.
International Nuclear Information System (INIS)
Amiro, B.D.
1997-01-01
The environmental assessment of deep geologic disposal of Canadian nuclear fuel waste considers many processes that could affect radionuclide transport to humans over thousands of years. Climatic change is an important feature that will occur over these long times. Glaciation will likely occur within the next 100,000 years over much of Canada, and its impact on radiological doses has been assessed previously. In the present study, we investigate the potential effect of short- term climatic change, usually associated with global warming caused by increases in atmospheric trace gases. We study the main biosphere transport pathways causing a radiological dose to humans from 129 I, which is the most important radionuclide in disposal of Canadian used nuclear fuel. Irrigation of a garden with contaminated well water is the main pathway and it can be affected by changes in temperature and precipitation. A cold, wet climate decreases the need for irrigation, and this decreases the radiological dose. A drastic climatic change, such as an increase in temperature from 10 to 20 degrees C and decrease in precipitation from 0.3 to 0.2 m during the growing season, is estimated to increase the dose by a factor of four. This is a relatively small change compared to the range of doses that arise from the variability and uncertainty in many of the parameters used in the environmental assessment models. Therefore, it is likely that the results of probabilistic dose assessment models can include the consequences of short-term climatic change. 39 refs., 3 figs
Potential of primary kidney cells for somatic cell nuclear transfer mediated transgenesis in pig
Directory of Open Access Journals (Sweden)
Richter Anne
2012-11-01
Full Text Available Abstract Background Somatic cell nuclear transfer (SCNT is currently the most efficient and precise method to generate genetically tailored pig models for biomedical research. However, the efficiency of this approach is crucially dependent on the source of nuclear donor cells. In this study, we evaluate the potential of primary porcine kidney cells (PKCs as cell source for SCNT, including their proliferation capacity, transfection efficiency, and capacity to support full term development of SCNT embryos after additive gene transfer or homologous recombination. Results PKCs could be maintained in culture with stable karyotype for up to 71 passages, whereas porcine fetal fibroblasts (PFFs and porcine ear fibroblasts (PEFs could be hardly passaged more than 20 times. Compared with PFFs and PEFs, PKCs exhibited a higher proliferation rate and resulted in a 2-fold higher blastocyst rate after SCNT and in vitro cultivation. Among the four transfection methods tested with a GFP expression plasmid, best results were obtained with the NucleofectorTM technology, resulting in transfection efficiencies of 70% to 89% with high fluorescence intensity, low cytotoxicity, good cell proliferation, and almost no morphological signs of cell stress. Usage of genetically modified PKCs in SCNT resulted in approximately 150 piglets carrying at least one of 18 different transgenes. Several of those pigs originated from PKCs that underwent homologous recombination and antibiotic selection before SCNT. Conclusion The high proliferation capacity of PKCs facilitates the introduction of precise and complex genetic modifications in vitro. PKCs are thus a valuable cell source for the generation of porcine biomedical models by SCNT.
Energy Technology Data Exchange (ETDEWEB)
Song, Kai [Department of Oral and Maxillofacial Surgery, The Affiliated Hospital of Qingdao University, Shandong Province (China); The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine Ministry of Education, Wuhan University, Wuhan (China); Song, Yong [The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine Ministry of Education, Wuhan University, Wuhan (China); Department of Stomatology, Liu Zhou People' s Hospital, Guangxi (China); Zhao, Xiao-Ping; Shen, Hui; Wang, Meng; Yan, Ting-lin [The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine Ministry of Education, Wuhan University, Wuhan (China); Liu, Ke, E-mail: liuke.1999@aliyun.com [Department of Oral and Maxillofacial-Head and Neck oncology, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079 (China); The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine Ministry of Education, Wuhan University, Wuhan (China); Shang, Zheng-jun, E-mail: shangzhengjun@hotmail.com [Department of Oral and Maxillofacial-Head and Neck oncology, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079 (China); The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine Ministry of Education, Wuhan University, Wuhan (China)
2014-10-15
Most previous studies have linked cancer–macrophage fusion with tumor progression and metastasis. However, the characteristics of hybrid cells derived from oral cancer and endothelial cells and their involvement in cancer remained unknown. Double-immunofluorescent staining and fluorescent in situ hybridization (FISH) were performed to confirm spontaneous cell fusion between eGFP-labeled human umbilical vein endothelial cells (HUVECs) and RFP-labeled SCC9, and to detect the expression of vementin and cytokeratin 18 in the hybrids. The property of chemo-resistance of such hybrids was examined by TUNEL assay. The hybrid cells in xenografted tumor were identified by FISH and GFP/RFP dual-immunofluoresence staining. We showed that SCC9 cells spontaneously fused with cocultured endothelial cells, and the resultant hybrid cells maintained the division and proliferation activity after re-plating and thawing. Such hybrids expressed markers of both parental cells and became more resistant to chemotherapeutic drug cisplatin as compared to the parental SCC9 cells. Our in vivo data indicated that the hybrid cells contributed to tumor composition by using of immunostaining and FISH analysis, even though the hybrid cells and SCC9 cells were mixed with 1:10,000, according to the FACS data. Our study suggested that the fusion events between oral cancer and endothelial cells undergo nuclear fusion and acquire a new property of drug resistance and consequently enhanced survival potential. These experimental findings provide further supportive evidence for the theory that cell fusion is involved in cancer progression. - Highlights: • The fusion events between oral cancer and endothelial cells undergo nuclear fusion. • The resulting hybrid cells acquire a new property of drug resistance. • The resulting hybrid cells express the markers of both parental cells (i.e. vimentin and cytokeratin 18). • The hybrid cells contribute to tumor repopulation in vivo.
Potentiality of Using Vertical and Three-Dimensional Isolation Systems in Nuclear Structures
Directory of Open Access Journals (Sweden)
Zhiguang Zhou
2016-10-01
Full Text Available Although the horizontal component of an earthquake response can be significantly reduced through the use of conventional seismic isolators, the vertical component of excitation is still transmitted directly into the structure. Records from instrumented structures, and some recent tests and analyses have actually seen increases in vertical responses in base isolated structures under the combined effects of horizontal and vertical ground motions. This issue becomes a great concern to facilities such as a Nuclear Power Plants (NPP, with specialized equipment and machinery that is not only expensive, but critical to safe operation. As such, there is considerable interest worldwide in vertical and three-dimensional (3D isolation systems. This paper examines several vertical and 3D isolation systems that have been proposed and their potential application to modern nuclear facilities. In particular, a series of case study analyses of a modern NPP model are performed to examine the benefits and challenges associated with 3D isolation compared with horizontal isolation. It was found that compared with the general horizontal isolators, isolators that have vertical frequencies of no more than 3 Hz can effectively reduce the vertical in-structure responses for the studied NPP model. Among the studied cases, the case that has a vertical isolation frequency of 3 Hz is the one that can keep the horizontal period of the isolators as the first period while having the most flexible vertical isolator properties. When the vertical frequency of isolators reduces to 1 Hz, the rocking effect is obvious and rocking restraining devices are necessary.
Yurt Lambrecht, Fatma; Ocakoglu, Kasim; Er, Ozge; Ince, Mine; Gunduz, Cumhur; Kayabası, Cagla
2016-05-15
Photodynamic therapy (PDT) is based on exposing a light-sensitive material that has been localized in target tissues with visible light. In the current study, symmetric Zn(II) octaoctadodecylphthalocyanine (1) and the asymmetrically substituted hydroxyhexyloxy derivative (2) were examined as a multifunctional agent for tumour nuclear imaging and for PDT potential. Zn(II)Pc 1 and Zn(II)Pc 2 were radiolabelled with (131) I using an iodogen method with high efficiency (93.5 ± 3.5% and 93.0 ± 2.8%, respectively) under the optimum conditions. Biodistribution study results showed that radiolabelled Zn(II)Pc 1 had a high uptake in the large intestine and unchanging uptake in the ovary. However, radiolabelled Zn(II)Pc 2 uptake was statically significant in the large intestine, pancreas, ovary and lung. For the PDT studies, EMT6/P (mouse mammary cell line) and HeLa (cervical adenocarcinoma cell line) with Zn(II)Pc 1 and Zn(II)Pc 2 were exposed to red light (650 nm) at 10-30 J/cm(2) . Zn(II)Pc 1 and Zn(II)Pc 2 had a good PDT efficacy in the EMT6/P cell line. In conclusion, radiolabelled Zn(II)Pc 1 might be a promising imaging agent for pancreas, ovary and colon tumours. However, the radiolabelled Zn(II)Pc 2 might be a promising nuclear imaging and PDT agent for colon, lung, pancreas and ovary tumours. Copyright © 2016 John Wiley & Sons, Ltd.
International Nuclear Information System (INIS)
Yoo, Keun Young
1998-01-01
This study was conducted to evaluate the health hazard of potential exposure to ionizing radiation among nuclear workers of the KEPCO and community residents nearby nuclear power plants since 1990 in Korea. The objectives of this study encompass 1) to delineate the relationship between cancer occurrence in the target population and radiation possibly emitted from the nuclear power plant, and 2) to provide special health service for health promotion of the community residents including periodic health examinations. The phase I study has been conducted during 1990-1995, which will be followed up by the phase II study until 2003. Hereby the interim report on the phase I study will be presented. As a baseline survey, the cross-sectional comparison shows that there were no significant difference in the health status of nuclear workers and control groups. This prospective study could eventually provide a valid conclusion on the causal relationship of radiation and cancer occurrence among residents nearby nuclear power plants through the phase II study which will be launched out during 1998-2000. (Cho, G. S.)
International Nuclear Information System (INIS)
Li Qingfeng; Guo Chenchen; Li Yongjia
2013-01-01
The terms of initialization, equation of state (EoS), and two-body collision in the updated ultrarelativistic quantum molecular dynamics (UrQMD) model are examined in details so as to systematically study the collective flows and the nuclear stopping of free nucleons and light clusters from heavy-ion collisions at INDRA energies. It is seen that at INDRA energies the dynamic transport with a soft EoS with momentum dependence and with the momentum-modified density-dependent nucleon-nucleon elastic cross sections describes the directed flow exhibited by hydrogen isotopes (Z = 1) emitted at midrapidity fairly well. The sensitivity of the balance energy (E bal ) of the directed flow to the strength parameter of the density dependence of symmetry potential energy is further studied with the same parameter set. It is found that the E bal of neutrons from HICs is particularly sensitive to the density dependence of the symmetry potential energy, while that of protons is not. And, the initial neutron/proton ratio dependence of the balance energy of neutrons from Sn isotopes can be taken as a useful probe to constrain the stiffness of the nuclear symmetry energy. (authors)
Analytic approach to constructing effective local potentials in nuclear reaction theory
International Nuclear Information System (INIS)
Blokhintsev, L.D.; Safronov, A.N.; Safronov, A.A.
2004-01-01
Full text: Recently a method of constructing effective local potentials between strongly interacting composite particles was suggested [1]. The approach is based on the requirement of the proper structure of the nearest to the physical region singularities of scattering amplitudes as well as on the methods of the inverse scattering problem. In the given work the method is generalized to the case of the presence of the long-range Coulomb interaction which drastically changes the analytic structure of the S matrix. The effective potential is defined as the local operator which, being inserted into the Lippmann-Schwinger equation, generates required discontinuities of partial-wave scattering amplitudes. Its strong part is written in the form V(r)=∫ μ 0 C(α)e -ar dα, where μ is determined by the position of the nearest to the physical region dynamical singularity. For all the processes considered, these singularities correspond to pole Feynman diagrams describing the elastic transfer mechanism. The C(α) function is found as a solution of the inverse scattering problem equations, the kernels of which are determined by the discontinuities at the nearest dynamical cuts. The Coulomb interaction is treated by introducing reduced Coulomb-nuclear scattering amplitudes and, in addition, by taking into account Coulomb corrections in the three-particle intermediate states and in the vertex functions of the pole diagrams. The processes of nd, pd, p 3 He, nα, pα and 3 Heα scattering were considered. To calculate the required discontinuities, the information on the corresponding vertex constants and binding energies was used. Effective potentials, scattering lengths and low-energy phase shifts for the processes under consideration were obtained. The work was supported by the Russian Foundation for Basic Research (grant No.04-02-16602) and by the 'Russian Universities' program (grant No. 02.02.027)
Gravity Cutoff in Theories with Large Discrete Symmetries
Dvali, Gia; Sibiryakov, Sergey; Vainshtein, Arkady
2008-01-01
We set an upper bound on the gravitational cutoff in theories with exact quantum numbers of large N periodicity, such as Z_N discrete symmetries. The bound stems from black hole physics. It is similar to the bound appearing in theories with N particle species, though a priori, a large discrete symmetry does not imply a large number of species. Thus, there emerges a potentially wide class of new theories, that address the hierarchy problem by lowering the gravitational cutoff due to existence of large Z_{10^32}-type symmetries.
Gravity Cutoff in Theories with Large Discrete Symmetries
International Nuclear Information System (INIS)
Dvali, Gia; Redi, Michele; Sibiryakov, Sergey; Vainshtein, Arkady
2008-01-01
We set an upper bound on the gravitational cutoff in theories with exact quantum numbers of large N periodicity, such as Z N discrete symmetries. The bound stems from black hole physics. It is similar to the bound appearing in theories with N particle species, though a priori, a large discrete symmetry does not imply a large number of species. Thus, there emerges a potentially wide class of new theories that address the hierarchy problem by lowering the gravitational cutoff due to the existence of large Z 10 32 -type symmetries
Current understanding of the pseudospin symmetry in atomic nuclei
International Nuclear Information System (INIS)
Marcos, S; Niembro, R; Lopez-Quelle, M; Savushkin, L N
2008-01-01
We use the relativistic mean field framework to analyse the reliability of the explanation of the pseudospin symmetry (PSS) that has been accepted, quite generally, by the scientific community, in the last decade. We make a comparative analysis of the mechanisms responsible for the breaking of the spin and pseudospin symmetries that shows the different nature of these symmetries. We propose an explanation of the PSS, also valid in the nonrelativistic limit, in which the effect of the deviation of the single-particle central potential from a harmonic oscillator on the breaking of the degeneracy of pseudospin doublets is partially compansated by the effect of the spin-orbit interaction.
Energy Technology Data Exchange (ETDEWEB)
Peskin, M.E. [Stanford Univ., CA (United States)
1994-12-01
When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics.
Gravitation and Gauge Symmetries
Stewart, J
2002-01-01
The purpose of this book (I quote verbatim from the back cover) is to 'shed light upon the intrinsic structure of gravity and the principle of gauge invariance, which may lead to a consistent unified field theory', a very laudable aim. The content divides fairly clearly into four sections (and origins). After a brief introduction, chapters 2-6 review the 'Structure of gravity as a theory based on spacetime gauge symmetries'. This is fairly straightforward material, apparently based on a one-semester graduate course taught at the University of Belgrade for about two decades, and, by implication, this is a reasonably accurate description of its level and assumed knowledge. There follow two chapters of new material entitled 'Gravity in flat spacetime' and 'Nonlinear effects in gravity'. The final three chapters, entitled 'Supersymmetry and supergravity', 'Kaluza-Klein theory' and 'String theory' have been used for the basis of a one-semester graduate course on the unification of fundamental interactions. The boo...
Segmentation Using Symmetry Deviation
DEFF Research Database (Denmark)
Hollensen, Christian; Højgaard, L.; Specht, L.
2011-01-01
and evaluate the method. The method uses deformable registration on computed tomography(CT) to find anatomical symmetry deviations of Head & Neck squamous cell carcinoma and combining it with positron emission tomography (PET) images. The method allows the use anatomical and symmetrical information of CT scans...... segmentations on manual contours was evaluated using concordance index and sensitivity for the hypopharyngeal patients. The resulting concordance index and sensitivity was compared with the result of using a threshold of 3 SUV using a paired t-test. Results: The anatomical and symmetrical atlas was constructed...... and sensitivity of respectively 0.43±0.15 and 0.56±0.18 was acquired. It was compared to the concordance index of segmentation using absolute threshold of 3 SUV giving respectively 0.41±0.16 and 0.51±0.19 for concordance index and sensitivity yielding p-values of 0.33 and 0.01 for a paired t-test respectively....
International Nuclear Information System (INIS)
Peskin, M.E.
1994-01-01
When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics
Quark diquark symmetry breaking
International Nuclear Information System (INIS)
Souza, M.M. de
1980-01-01
Assuming the baryons are made of quark-diquark pairs, the wave functions for the 126 allowed ground states are written. The quark creation and annihilations operators are generalized to describe the quark-diquark structure in terms of a parameter σ. Assuming that all quark-quark interactions are mediated by gluons transforming like an octet of vector mesons, the effective Hamiltonian and the baryon masses as constraint equations for the elements of the mass matrix is written. The symmetry is the SU(6) sub(quark)x SU(21) sub(diquark) broken by quark-quark interactions respectively invariant under U(6), U(2) sub(spin), U(3) and also interactions transforming like the eighth and the third components of SU(3). In the limit of no quark-diquark structure (σ = 0), the ground state masses is titted to within 1% of the experimental data, except for the Δ(1232), where the error is almost 2%. Expanding the decuplet mass equations in terms of σ and keeping terms only up to the second order, this error is reduced to 67%. (Author) [pt
Scale symmetry and virial theorem
International Nuclear Information System (INIS)
Westenholz, C. von
1978-01-01
Scale symmetry (or dilatation invariance) is discussed in terms of Noether's Theorem expressed in terms of a symmetry group action on phase space endowed with a symplectic structure. The conventional conceptual approach expressing invariance of some Hamiltonian under scale transformations is re-expressed in alternate form by infinitesimal automorphisms of the given symplectic structure. That is, the vector field representing scale transformations leaves the symplectic structure invariant. In this model, the conserved quantity or constant of motion related to scale symmetry is the virial. It is shown that the conventional virial theorem can be derived within this framework
Symmetry breaking and restoration in Lifshitz type theories
International Nuclear Information System (INIS)
Farakos, K.; Metaxas, D.
2012-01-01
We consider the one-loop effective potential at zero and finite temperature in scalar field theories with anisotropic space-time scaling. For z=2, there is a symmetry breaking term induced at one loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature. For z=3, we considered at first the case with a positive mass term at tree level and found no symmetry breaking effects induced at one loop, and then we study the case with a negative mass term at tree level where we cannot conclude about symmetry restoration effects at high temperature because of the imaginary parts that appear in the effective potential for small values of the scalar field.
International Nuclear Information System (INIS)
1980-06-01
This volume of the Nonproliferation Alternative Systems Assessment Program (NASAP) report provides time and cost estimates for positioning new nuclear power systems for commercial deployment. The assessment also estimates the rates at which the new systems might penetrate the domestic market, assuming the continuing viability of the massive light-water reactor network that now exists worldwide. This assessment does not recommend specific, detailed program plans and budgets for individual systems; however, it is clear from this analysis that any of the systems investigated could be deployed if dictated by national interest
Energy Technology Data Exchange (ETDEWEB)
1980-06-01
This volume of the Nonproliferation Alternative Systems Assessment Program (NASAP) report provides time and cost estimates for positioning new nuclear power systems for commercial deployment. The assessment also estimates the rates at which the new systems might penetrate the domestic market, assuming the continuing viability of the massive light-water reactor network that now exists worldwide. This assessment does not recommend specific, detailed program plans and budgets for individual systems; however, it is clear from this analysis that any of the systems investigated could be deployed if dictated by national interest.
Potential application of nuclear remote-handling technology to underwater inspection and maintenance
International Nuclear Information System (INIS)
Eccleston, M.J.
1990-01-01
Examples are given of remote handling equipment developed within the nuclear industry and employing telemanipulative or telerobotic principles. In telerobotics the nuclear industry has been following a trend towards increased levels of autonomy, delegating operator control to a computer, for example, in resolved rate manipulator tip control, teach-and-repeat control and collision avoidance. Illustrations are presented of remote-handling techniques from the nuclear industry which may be carried over into undersea remote inspection, maintenance and repair systems. (author)
The American approach to the solution of Iranian nuclear potential problem
Directory of Open Access Journals (Sweden)
Pavliuk Olesia Igorivna
2013-11-01
Full Text Available The possible vectors of cooperation with Iran concerning its nuclear weapons accumulation is analyzed in this article. The author considers the main scenarios of the international relations under conditions of sanctions and other coercive measures ineffectiveness in stopping Iran’s nuclear program. The study examines the foreign policy of Barack Obama according to the Islamic Republic of Iran (IRI and American experts’ main approaches to settle escalating nuclear capability of IRI problem.
International Nuclear Information System (INIS)
1990-04-01
This report contains brief discussion on the following tapes: giant resonances; nucleus-nucleus reactions; nuclear astrophysics; polarization; fundamental symmetries and interactions; accelerator mass spectrometry; instrumentation; accelerators and in sources; and computer systems
International Nuclear Information System (INIS)
Lisovsky, I.; Baklanov, A.; Jacovlev, V.; Prutskov, V.; Bergman, R.
1999-05-01
This Technical Report, being part of the INTAS project 96-1802, constitutes a comprehensive presentation - covering basic results from separate contributions as specified below - of work performed during the first period (February 1998- February 1999). The aim of the INTAS project 96-1802: 'Assessment of potential risk of environmental radioactive contamination in northern Europe from terrestrial nuclear units in north-west Russia' is to assess the potential risk of environmental radioactive contamination from nuclear units in north-west Russia and resulting impacts on population and terrestrial ecosystems in the north. The work focuses mainly on airborne radioactive contamination, but some case studies also deal with accidental leakage from terrestrial nuclear sites to soil and coastal waters. The present material comprises in more detail the contributions from participants no.4 and no.5 based on the four internal reports referred to below: (1) Assessment of potential risk of environmental radioactive contamination in Northern Europe from terrestrial nuclear units in north-west Russia: 'Determination of the list of typical sources of danger emergency radioactive releases in an environment in connection with military activity in the North of Russia.' Technical report no.1 of the team no.5. St.-Petersburg State Technical University, St.-Petersburg. July 1998. 43 p.; (2) Assessment of potential risk of environmental radioactive contamination in Northern Europe from terrestrial nuclear units in North-west Russia: 'Analysis and description of source-term characteristics for accident linked with airborne radioactive releases from Kola Nuclear Power Plant. Establishing a network facility at INEP for communication among the INTAS Project participants.' Technical report no.1 of the team no.4. Kola Science Centre, Apatity. August 1998. 56 p.; (3) Assessment of potential risk of environmental radioactive contamination in Northern Europe from terrestrial nuclear units in
Energy Technology Data Exchange (ETDEWEB)
Lisovsky, I. [St. Petersburg State Technical Univ. (Russian Federation); Baklanov, A. [Inst. of the Northern Ecology Problems (INEP) (Russian Federation); Jacovlev, V. [St. Petersburg State Technical Univ. (Russian Federation); Prutskov, V. [Ministry of Defence (Russian Federation). First Central Research Inst. of Naval Shipbuilding; Tarasov, I. [Ministry of Defence (Russian Federation). 23 State Marine Project Inst.; Blecher, A. [State Unitary Enterprise (Russian Federation). Research Inst. of Industrial and Marine Medicine; Zvonariev, B.; Kuchin, N.; Rubanov, S.; Sergeiev, I. [State Scientific Centre (Russian Federation). Central Research Inst. of A. Krylov; Morozov, S.; Koshkin, V.; Fedorenko, Yu.; Rigina, O. [Inst. of the Northern Ecology Problems (INEP) (Russian Federation); Bergman, R. [ed.] [Defence Research Establishment, Umeaa (Sweden). Div. of NBC Defence
1999-05-01
This Technical Report, being part of the INTAS project 96-1802, constitutes a comprehensive presentation - covering basic results from separate contributions as specified below - of work performed during the first period (February 1998- February 1999). The aim of the INTAS project 96-1802: `Assessment of potential risk of environmental radioactive contamination in northern Europe from terrestrial nuclear units in north-west Russia` is to assess the potential risk of environmental radioactive contamination from nuclear units in north-west Russia and resulting impacts on population and terrestrial ecosystems in the north. The work focuses mainly on airborne radioactive contamination, but some case studies also deal with accidental leakage from terrestrial nuclear sites to soil and coastal waters. The present material comprises in more detail the contributions from participants no.4 and no.5 based on the four internal reports referred to below: (1) Assessment of potential risk of environmental radioactive contamination in Northern Europe from terrestrial nuclear units in north-west Russia: `Determination of the list of typical sources of danger emergency radioactive releases in an environment in connection with military activity in the North of Russia.` Technical report no.1 of the team no.5. St.-Petersburg State Technical University, St.-Petersburg. July 1998. 43 p.; (2) Assessment of potential risk of environmental radioactive contamination in Northern Europe from terrestrial nuclear units in North-west Russia: `Analysis and description of source-term characteristics for accident linked with airborne radioactive releases from Kola Nuclear Power Plant. Establishing a network facility at INEP for communication among the INTAS Project participants.` Technical report no.1 of the team no.4. Kola Science Centre, Apatity. August 1998. 56 p.; (3) Assessment of potential risk of environmental radioactive contamination in Northern Europe from terrestrial nuclear units in
International Nuclear Information System (INIS)
Broxton, D.E.; Warren, R.G.; Hagan, R.C.; Luedemann, G.
1986-10-01
The chemistry of diagenetically altered tuffs at a potential nuclear waste repository, Yucca Mountain, Nevada is described. These tuffs contain substantial amounts of zeolites that are highly sorptive of certain radionuclides. Because of their widespread distribution, the zeolitic tuffs could provide important barriers to radionuclide migration. Physical properties of these tuffs and of their constituent zeolites are influenced by their chemical compositions. This study defines the amount of chemical variability within diagenetically altered tuffs and within diagenetic minerals at Yucca Mountain. Zeolitic tuffs at Yucca Mountain formed by diagenetic alteration of rhyolitic vitric tuffs. Despite their similar starting compositions, these tuffs developed compositions that vary both vertically and laterally. Widespread chemical variations were the result of open-system chemical diagenesis in which chemical components of the tuffs were mobilized and redistributed by groundwaters. Alkalies, alkaline earths, and silica were the most mobile elements during diagenesis. The zeolitic tuffs can be divided into three compositional groups: (1) calcium- and magnesium-rich tuffs associated with relatively thin zones of alteration in the unsaturated zone; (2) tuffs in thick zones of alteration at and below the water table that grade laterally from sodic compositions on the western side of Yucca Mountain to calcic compositions on the eastern side; and (3) potassic tuffs at the north end of Yucca Mountain. Physical properties of tuffs and their consistuent zeolites at Yucca Mountain may be affected by variations in compositions. Properties important for assessment of repository performance include behavior and ion exchange
Criteria for seismic evaluation and potential design fixes for WWER type nuclear power plants
International Nuclear Information System (INIS)
Stevenson, J.D.
1995-01-01
The purpose for this document is to provide a criteria for the seismic evaluation and development of potential design fixes for structures, systems and components for the WWER type Nuclear power plants. The design fixes are divided into two categories, detailed and easy fixes. Detailed fixes are typically applicable to building structures, components for which there is little or no seismic capacity information, large tanks and vital systems and components which make up the reactor cooling system and components which perform support or auxiliary functions. In case of the design of 'easy fixes', the criteria presented may be used for both the seismic design as well as for the evaluation of structures, systems and components to which easy fix design applies. Easy fixes are situations where seismic capacities of structures, systems and components can be significantly increased with relatively minor, inexpensive fixes usually associated with anchorage modification of safety related structures, systems and components or those that could interact with safety related structures, systems and components. Often these fixes can be accomplished while the plant is in operation
Fischer, Cornelius; Finkeldei, Sarah; Brandt, Felix; Bosbach, Dirk; Luttge, Andreas
2015-08-19
The long-term stability of ceramic materials that are considered as potential nuclear waste forms is governed by heterogeneous surface reactivity. Thus, instead of a mean rate, the identification of one or more dominant contributors to the overall dissolution rate is the key to predict the stability of waste forms quantitatively. Direct surface measurements by vertical scanning interferometry (VSI) and their analysis via material flux maps and resulting dissolution rate spectra provide data about dominant rate contributors and their variability over time. Using pyrochlore (Nd2Zr2O7) pellet dissolution under acidic conditions as an example, we demonstrate the identification and quantification of dissolution rate contributors, based on VSI data and rate spectrum analysis. Heterogeneous surface alteration of pyrochlore varies by a factor of about 5 and additional material loss by chemo-mechanical grain pull-out within the uppermost grain layer. We identified four different rate contributors that are responsible for the observed dissolution rate range of single grains. Our new concept offers the opportunity to increase our mechanistic understanding and to predict quantitatively the alteration of ceramic waste forms.
Potential use of nuclear irradiation technology for the microbial industry in Malaysia
International Nuclear Information System (INIS)
Raja, P.; Isyanti, I.
2002-01-01
The potential application of irradiation is numerous. The process seems technically feasible for sterilization of medical devices, pharmaceutical products, foods, cosmetics, packaging materials, scientific laboratory materials like petri dishes, growth media, complying with phytosanitary requirements for fruit and vegetables etc. An awareness of biofertilizer or microbial product has established itself to be a significant part of food production and consumption internationally as well as in Malaysia. People are discovering organic agriculture can serve their need for safe quality food, environment conservation and social accountability. One of the major technical constraints of viable microbial or biofertilizer product production is contaminated free carrier materials. In order to develop the good microbial product, we are practicing the gamma irradiation on our carrier materials and successfully established the product. The different carrier materials were packed and used 25 kGy Cobalt-60 source (JS 8900, SINAGAMA, MINT) for sterilization and simultaneously the materials were sterilized in steam. The cultured Trichoderma virile and T harzianum were mixed with sterilized carrier and observed the colony formin. unit (CFU) on regular intervals. The results showed the efficient colony forming unit on both sterilization method of materials. However, the nuclear irradiation is more cost effective and time saving than steam method. (Author)
Directory of Open Access Journals (Sweden)
Sara B Estruch
Full Text Available Nuclear orphan receptor TLX (NR2E1 functions primarily as a transcriptional repressor and its pivotal role in brain development, glioblastoma, mental retardation and retinopathologies make it an attractive drug target. TLX is expressed in the neural stem cells (NSCs of the subventricular zone and the hippocampus subgranular zone, regions with persistent neurogenesis in the adult brain, and functions as an essential regulator of NSCs maintenance and self-renewal. Little is known about the TLX social network of interactors and only few TLX coregulators are described. To identify and characterize novel TLX-binders and possible coregulators, we performed yeast-two-hybrid (Y2H screens of a human adult brain cDNA library using different TLX constructs as baits. Our screens identified multiple clones of Atrophin-1 (ATN1, a previously described TLX interactor. In addition, we identified an interaction with the oncoprotein and zinc finger transcription factor BCL11A (CTIP1/Evi9, a key player in the hematopoietic system and in major blood-related malignancies. This interaction was validated by expression and coimmunoprecipitation in human cells. BCL11A potentiated the transrepressive function of TLX in an in vitro reporter gene assay. Our work suggests that BCL11A is a novel TLX coregulator that might be involved in TLX-dependent gene regulation in the brain.
Estruch, Sara B; Buzón, Víctor; Carbó, Laia R; Schorova, Lenka; Lüders, Jens; Estébanez-Perpiñá, Eva
2012-01-01
Nuclear orphan receptor TLX (NR2E1) functions primarily as a transcriptional repressor and its pivotal role in brain development, glioblastoma, mental retardation and retinopathologies make it an attractive drug target. TLX is expressed in the neural stem cells (NSCs) of the subventricular zone and the hippocampus subgranular zone, regions with persistent neurogenesis in the adult brain, and functions as an essential regulator of NSCs maintenance and self-renewal. Little is known about the TLX social network of interactors and only few TLX coregulators are described. To identify and characterize novel TLX-binders and possible coregulators, we performed yeast-two-hybrid (Y2H) screens of a human adult brain cDNA library using different TLX constructs as baits. Our screens identified multiple clones of Atrophin-1 (ATN1), a previously described TLX interactor. In addition, we identified an interaction with the oncoprotein and zinc finger transcription factor BCL11A (CTIP1/Evi9), a key player in the hematopoietic system and in major blood-related malignancies. This interaction was validated by expression and coimmunoprecipitation in human cells. BCL11A potentiated the transrepressive function of TLX in an in vitro reporter gene assay. Our work suggests that BCL11A is a novel TLX coregulator that might be involved in TLX-dependent gene regulation in the brain.
Kojima, Hiroyuki; Takeuchi, Shinji; Itoh, Toshihiro; Iida, Mitsuru; Kobayashi, Satoshi; Yoshida, Takahiko
2013-12-06
Various organophosphate flame retardants (OPFRs) are widely used in building materials, textiles and electric appliances, and have been reported to cause indoor environmental pollution in houses and office buildings. In this study, using cell-based transactivation assays, we characterized the agonistic and/or antagonistic activities of 11 OPFRs against human nuclear receptors; estrogen receptor α (ERα), ERβ, androgen receptor (AR), glucocorticoid receptor (GR), thyroid hormone receptor α1 (TRα1), TRβ1, retinoic acid receptor α (RARα), retinoid X receptor α (RXRα), pregnane X receptor (PXR), peroxisome proliferator-activated receptor α (PPARα), and PPARγ. Of the 11 OPFRs tested, triphenyl phosphate (TPhP) and tricrecyl phosphate (TCP) showed ERα and/or ERβ agonistic activity. In addition, tributyl phosphate (TBP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), TPhP and TCP showed AR antagonistic activity, and TBP, tris(2-ethylhexyl) phosphate (TEHP), TDCPP, TPhP and TCP showed GR antagonistic activity. Furthermore, we found that seven compounds, TBP, tris(2-chloro-1-methylethyl) phosphate (TCPP), TEHP, tris(2-butoxyethyl) phosphate (TBEP), TDCPP, TPhP, and TCP, display PXR agonistic activity. However, none of test compounds showed agonistic or antagonistic activity against TRα/β, or agonistic activity against RARα, RXRα or PPARα/γ. Taken together, these results suggest that several OPFRs may have potential endocrine disrupting effects via ERα, ERβ, AR, GR and PXR. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
International Nuclear Information System (INIS)
Weil, L.
2000-01-01
The study covers nuclear installations in Germany that belong to the responsibility of the Federal Government or Land governments and have been decommisioned, or are earmarked for decommissioning. These installations include zero power reactors (training reactors) and research reactors as well as power reactors, reprocessing plants and hot cells. Both the Federal Government and the Land governments are looking for measures to minimize the cost for dismantling and waste management, as the estimated expenses to be paid from public funds amount to a total of approx. DM 18 billion. The study was to review the required dismantling and waste management activities for identifying economizing potentials. The installations examined for this purpose are: 1. the VVER power reactors of EWN at Greifswald, 2. the Braunschweig research and mesuring reactor (FMRB) of PTB Braunschweig, 3. the MERLIN research reactor of Juelich Research Center (FZJ), 4. the AVR reactor of Arbeitsgemeinschaft Versuchsreaktor (AVR) GmbH, 5. the sodium-cooled reactor KNK II of Karlsruhe Research Center (FZK), 6. the reprocessing plant (MILLI) of FZK, 7. the Rossendorf research reactor (RFR) of Verein f. Kernverfahrenstechnik und Analytik Rossendorf e.V. (VKTA), 9. the installations for molybdenum production (AMOR) of the VKTA at Rossendorf. It is expected that the results elaborated with this study can be used as a datapool and general basis for suitably modified application for other installations. (orig./CB) [de