Reactions with weakly bound nuclei at near barrier energies
International Nuclear Information System (INIS)
Nanal, Vandana
2014-01-01
In reactions with weakly bound nuclei, the effect of breakup on fusion process has attracted much attention in recent years. The experimental study shows that breakup channel leads to suppression of complete fusion at above barrier energies due to loss of flux. The fusion barrier distribution can provide a further insight into understanding the influence of coupling to the breakup channels. Similar information could be obtained from the elastic and quasielastic (QEL) scattering because of the conservation of the reaction flux (i.e. R+T= 1), where R is the reflection probability and T is the transmission probability. Thus, quasi-elastic scattering at backward angles is the counterpart of the fusion process and it is expected that the barrier distributions extracted from two processes, namely, QEL and fusion should be similar. While this is true for tightly bound reaction systems, in reactions involving weakly bound projectiles significant differences have been observed for QEL barrier distributions with and without inclusion of breakup processes. This talk will present the recent results for fusion and quasi-elastic scattering in "6","7Li + "1"9"7Au system. Developmental efforts towards a momentum achromatic separator, MARIE, to extract projectile-like secondary ion beams following the reactions of heavy-ion beams from superconducting LINAC booster at Mumbai will also be presented. (author)
Inclusive breakup of three-fragment weakly bound nuclei
International Nuclear Information System (INIS)
Carlson, B.V.; Frederico, T.; Hussein, M.S.
2017-01-01
The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.
Inclusive breakup of three-fragment weakly bound nuclei
Energy Technology Data Exchange (ETDEWEB)
Carlson, B.V.; Frederico, T. [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Hussein, M.S., E-mail: hussein@if.usp.br [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Instituto de Estudos Avançados, Universidade de São Paulo, C.P. 72012, 05508-970 São Paulo, SP (Brazil); Instituto de Física, Universidade de São Paulo, C.P. 66318, 05314-970 São Paulo, SP (Brazil)
2017-04-10
The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.
Recent results on fusion and direct reactions with weakly bound stable nuclei
International Nuclear Information System (INIS)
Shrivastava, A.
2011-01-01
Recent measurements of fusion and direct reactions in case of weakly bound stable nuclei at extreme sub-barrier energies using a sensitive off beam technique are presented. First section deals with deep sub-barrier fusion cross-section measurement for 67 Li + 198 Pt followed by the study of fragment capture reaction of 7 Li + 198 Pt. Deviation in the slope of the fusion excitation function, as observed in case of medium heavy systems, is absent in the present asymmetric systems at these low energies. This study shows the absence of fusion hindrance, suggesting modifications in models that explain deep sub-barrier fusion data to incorporate weakly bound asymmetric systems
Fusion enhancement/suppression and irreversibility in reactions induced by weakly bound nuclei
International Nuclear Information System (INIS)
Gomes, P.R.S.; Lubian, J.; Canto, L.F.; Chamon, L.C.; Crema, E.; Hussein, M.S.
2011-01-01
We show that halo effects enhance fusion cross sections of weakly bound systems, comparing with the situation when there is no-halo. We introduce dimensionless fusion functions and energy variable quantity to investigate systematical trends in the fusion cross sections of weakly bound nuclei at near-barrier energies. We observe very clearly complete fusion suppression at energies above the barrier due to dynamic effects of the breakup on fusion. We explain this suppression in terms of the repulsive polarization potential produced by the breakup. (author)
Study of the threshold anomaly in systems involving weakly bound nuclei
International Nuclear Information System (INIS)
Figueira, J.M.; Niello, J.O. Fernandez; Abelof, G.A.; Arazi, A.; Barmak, D.H.; Capurro, O.A.; Carnelli, P.; Fimiani, L.; Marti, G.V.; Heimann, D. Martinez; Negri, A.E.; Pacheco, A.J.; Gomes, P.R.S.; Lubian, J.; Monteiro, D.S.
2009-01-01
Full text: One of the dominant mechanisms in systems involving weakly bound nuclei is the break-up channel; however, the dynamics of this process remains poorly understood. In elastic scattering of strongly bound nuclei it is clearly established that there is always a threshold anomaly (TA) in the optical potential. The TA is characterized by a localized peak in the real part of the potential and by a decrease of the imaginary part of the potential as the bombarding energy decreases towards the Coulomb barrier. But when at least one of the nuclei is weakly bound the results are different for different systems. Three kinds of situations have been reported: the usual TA is observed; the usual TA is not observed because the potentials are almost constant even close to the Coulomb barrier; the so-called Break up Threshold Anomaly (BTA), where the imaginary potential increases as the bombarding energy decreases towards the Coulomb barrier. The BTA is attributed to a strong coupling of the elastic channel with the breakup process, which might have a much larger cross section than fusion at sub-barrier energies. In order to understand how those differences are affected by the system properties it is important to have data of new systems available. In this work we contribute original elastic scattering data of the weakly bound 6,7 Li projectiles on 144 Sm at near coulomb barrier energies. The measurements have been performed at the TANDAR Laboratory using 6 Li and 7 Li beams and a 100 μg/cm 2 thick 144 Sm target. Eleven different bombarding energies between 21 and 42.3 MeV were used for each projectile. The results are analyzed using phenomenological optical potentials and compared with results from other systems involving weakly bound nuclei. (author)
Reduction methodology for reaction cross sections induced by weakly bound nuclei
International Nuclear Information System (INIS)
Deshmukh, N.N.; Mukherjee, S.; Appannababu, S.; Guimaraees, V.; Lubian, J.; Gomes, P.R.S.
2009-01-01
The interest in nuclear reactions with weakly bound nuclei has increased considerably along the last decade. Several experiments with stable and unstable projectiles have been performed and a variety of theoretical approaches have been developed. In particular, fusion and breakup reactions induced by such projectiles have been the object of several studies. Owing to the weak binding of the projectile, the breakup cross section may be quite large and coupling with the breakup channel can strongly affect the fusion cross section at near barrier energies. This influence stems from two effects, one of a static and the other of a dynamic nature, which are, however, not easy to be disentangled. The static effect results from the more diffuse density of the weakly bound nuclei, as compared with a strongly bound one. The contribution from weakly bound nucleons to the nuclear density extends further out and this gives rise to a lower and thicker potential barrier. There is general understanding that this static effect enhances the fusion cross section at near barrier energies. On the other hand, there is the dynamic effect corresponding to the coupling with the breakup channel. It is well known that the coupling with a finite number of bound channels enhances the sub-barrier fusion cross section. However, the effect of coupling to channels in the continuum (breakup) is controversial. In first place, one should have in mind that there are different fusion processes in collisions of weakly bound projectiles. One of such processes is the complete fusion, which takes place when the whole mass of the projectile fuses with the target. There may be fusion following breakup. In this case, the compound nucleus may contain the whole mass of the projectile (through sequential fusion of the fragments), or some fragment can escape the interaction region. The former corresponds also to complete fusion (sequential complete fusion) while the latter is known as incomplete fusion. So far
Some peculiarities of interactions of weakly bound lithium nuclei at near-barrier energies
Kabyshev, A. M.; Kuterbekov, K. A.; Sobolev, Yu G.; Penionzhkevich, Yu E.; Kubenova, M. M.; Azhibekov, A. K.; Mukhambetzhan, A. M.; Lukyanov, S. M.; Maslov, V. A.; Kabdrakhimova, G. D.
2018-02-01
This paper presents new experimental data on the total cross sections of 9Li + 28Si reactions at low energies as well as the analysis of previously obtained data for 6,7Li. Based on a large collection of data (authors’ and literature data) we carried out a comparative analysis of the two main experimental interaction cross sections (angular distributions of the differential cross sections and total reaction cross sections) for weakly bound lithium (6-9Li, 11Li) nuclei in the framework of Kox parameterization and the macroscopic optical model. We identified specific features of these interactions and predicted the experimental trend in the total reaction cross sections for Li isotopes at energies close to the Coulomb barrier.
Recent developments in fusion and direct reactions with weakly bound nuclei
International Nuclear Information System (INIS)
Canto, L.F.; Gomes, P.R.S.; Donangelo, R.; Lubian, J.; Hussein, M.S.
2015-01-01
In this Report we give a balanced account of the experimental and theoretical advances acquired over the last decade in the field of near-barrier fusion reactions induced by weakly bound stable and unstable nuclei. The elastic scattering and breakup reactions of these systems are also extensively reviewed as they play an important role in the fusion process. We review several theoretical tools used in the description of the data. The concepts of Complete Fusion (CF), Incomplete Fusion (ICF) and Total Fusion (TF), which is the sum of CF and ICF, are discussed and recent work on the calculation of these quantities is reviewed. The Continuum Discretized Coupled Channels (CDCC) method and its semiclassical version are described in detail and their limitations are pointed out. More importantly, we describe the salient features of the conclusions reached from the more than 40 measurements made, over a decade, of near-barrier fusion, elastic scattering and breakup reactions, and confront these data with the CDCC or other methods appropriate for these processes at the energy regime in question.
International Nuclear Information System (INIS)
Gomes, P.R.S.
2011-01-01
Reactions involving weakly bound nuclei, especially halo nuclei, at near barrier energies, are an important subject not yet fully understood. Due to the low threshold energy for breakup, this process is particularly important and may affect significantly the fusion process and elastic scattering. In this talk I will show the systematic of results so far available in this field, concerning static and dynamical effects of halo and breakup on fusion and total reaction cross sections, the energy dependence of the optical potential on the elastic scattering and coupling effects on quasi-elastic scattering barrier distributions involving weakly bound nuclei, both stable and radioactive. The data to be discussed are new data from our group and from the literature, together with some older data. I will also present some experimental challenges for the development of this field. (author)
Role of nuclear couplings in the inelastic excitation of weakly-bound neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Dasso, C.H. [Niels Bohr Institute, Copenhagen (Denmark); Lenzi, S.M.; Vitturi, A. [Universita di Padova (Italy)
1996-12-31
Much effort is presently devoted to the study of nuclear systems far from the stability line. Particular emphasis has been placed in light systems such as {sup 11}Li, {sup 8}B and others, where the very small binding energy of the last particles causes their density distribution to extend considerably outside of the remaining nuclear core. Some of the properties associated with this feature are expected to characterize also heavier systems in the vicinity of the proton or neutron drip lines. It is by now well established that low-lying concentrations of multipole strength arise from pure configurations in which a peculiar matching between the wavelength of the continuum wavefunction of the particles and the range of the weakly-bound hole states occurs. To this end the authors consider the break-up of a weakly-bound system in a heavy-ion collision and focus attention in the inelastic excitation of the low-lying part of the continuum. They make use of the fact that previous investigations have shown that the multipole response in this region is not of a collective nature and describe their excited states as pure particle-hole configurations. Since the relevant parameter determining the strength distributions is the binding energy of the last bound orbital they find it most convenient to use single-particle wavefunctions generated by a sperical square-well potential with characteristic nuclear dimensions and whose depth has been adjusted to give rise to a situation in which the last occupied neutron orbital is loosely-bound. Spin-orbit couplings are, for the present purpose, ignored. The results of this investigation clearly indicate that nuclear couplings have the predominant role in causing projectile dissociation in many circumstances, even at bombarding energies remarkably below the Coulomb barrier.
The contour deformation method in momentum space and effective interactions for weakly bound nuclei
International Nuclear Information System (INIS)
Hagen, Gaute
2005-01-01
The main purpose of this thesis has been to investigate and develop methods suitable for study of resonance phenomena in nuclear and subatomic physics. Emphasis has been on the momentum space formulation of the Schrodinger equation. It has been shown; starting from the integral formulation of the Schrodinger equation, that an efficient way of obtaining a complete set of states including bound- antibound and resonant states is through the Contour Deformation Method. The strength of the Contour Deformation Method has been illustrated by studying a wide range of different cases in subatomic physics where resonance phenomena appear. These applications ranges from the case of a single-particle moving in a spherically symmetric field to the case of strong deformations of the field. Further, it has been studied how resonances may be solved for in complex potentials which models absorptive and emittive processes, using the Contour Deformation Method. The results obtained in these specific applications, strongly favour the Contour Deformation Method in comparison with other methods such as complex coordinate scaling and analytic continuation in the coupling strength. The most appealing feature of CD-NI is that not only does it give accurate results for resonances and anti-bound states, but in addition it provides us with a complete set of states which may be used in many different eigenfunction expansions. The only limitation of CDM is that the analytic structure of the potential has to be known, since the choice of contour is dictated by the singularity structure of the potential. The revival and study of CDM applied to nuclear physics, may be considered the main issue of the first part of this thesis, and is also the topic of Paper 1. In the second part of this thesis, the focus was directed towards the issue of how resonance phenomena may be understood in nuclei, when several valence particles are present. The newly developed Gamow Shell Model is a promising approach in
Relativistic effects in the study of weakly bound F and Be nuclei
Indian Academy of Sciences (India)
FAHIME REZVANI
2018-01-03
Jan 3, 2018 ... equations in various fields of physics [6–12]. The equa- ... Within the framework of the Dirac equation, ... is only an approximation; the quality of approximation ... nuclei, the nucleon angular momentum J and spin–orbit.
International Nuclear Information System (INIS)
Walecka, J.D.
1983-01-01
Nuclei provide systems where the strong, electomagnetic, and weak interactions are all present. The current picture of the strong interactions is based on quarks and quantum chromodynamics (QCD). The symmetry structure of this theory is SU(3)/sub C/ x SU(2)/sub W/ x U(1)/sub W/. The electroweak interactions in nuclei can be used to probe this structure. Semileptonic weak interactions are considered. The processes under consideration include beta decay, neutrino scattering and weak neutral-current interactions. The starting point in the analysis is the effective Lagrangian of the Standard Model
Role of external neutrons of weakly bound nuclei in reactions with their participation
Naumenko, M. A.; Penionzhkevich, Yu E.; Samarin, V. V.; Sobolev, Yu G.
2018-05-01
The paper presents the results of measurement of the total cross sections for reactions 4,6He+Si and 6,7,9Li+Si in the beam energy range 5–50 A MeV. The enhancements of the total cross sections for reaction 6He+Si compared with reaction 4He+Si and 9Li+Si compared with reactions 6,7Li+Si have been observed. The performed microscopic analysis of total cross sections for reactions 6He+Si and 9Li+Si based on numerical solution of the time-dependent Schrödinger equation for external neutrons of projectile nuclei 6He and 9Li yielded good agreement with experimental data.
International Nuclear Information System (INIS)
Lapoux, V.
2005-09-01
Information on the structure, spectroscopy and target interaction potentials of exotic nuclei can be inferred by interpreting measured data from direct reactions on proton such as elastic or inelastic scattering of proton (p,p') or one-nucleon transfer reaction (p,d). A series of experimental results has been obtained at the GANIL facilities on the setting composed of the MUST telescope array used for the detection of light charged-particles and of CATS beam detectors. This setting aims at measuring reactions on light proton or deuteron targets through reverse kinematics. Particularly, results on C 10 , C 11 and on direct reactions with the He 8 beam of Spiral are presented. The first chapter is dedicated to the description of the most important theories concerning the nucleus. The experimental tools used to probe the nucleus are reported in the second chapter. The third and fourth chapters present the framework that has allowed us to analyse results from (p,p') and (p,d) reactions on weakly bound exotic nuclei. The last chapter is dedicated to the description of future experimental programs. (A.C.)
International Nuclear Information System (INIS)
Figueira, J. M.; Arazi, A.; Carnelli, P.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Niello, J. O. Fernandez; Capurro, O. A.; Fimiani, L.; Marti, G. V.; Lubian, J.; Monteiro, D. S.; Gomes, P. R. S.
2010-01-01
Angular distributions for the elastic scattering of the weakly bound 6,7 Li+ 144 Sm systems were measured with high accuracy at bombarding energies from 85% up to 170% of the Coulomb barrier. An optical model analysis was performed, and the relevant parameters of the real and imaginary parts of the optical potential were extracted. The results are compared with those previously published for the tightly bound 12 C+ 144 Sm and 16 O+ 144 Sm systems. The usual threshold anomaly observed in the behavior of the potential of tightly bound systems was not observed for either weakly bound system. This absence is attributed to the repulsion due to breakup coupling which cancels the attraction arising from couplings with bound channels.
International Nuclear Information System (INIS)
Gomes, P. R. S.; Lubian, J.; Mendes-Junior, D. R.; Faria, P. N. de; Linares, R.; Sigaud, L.; Rangel, J.; Ferreira, J. L.; Paes, B.; Cardozo, E. N.; Cortes, M. R.; Canto, L. F.; Ermamatov, M. J.; Otomar, D. R.; Ferioli, E.; Lotti, P.; Hussein, M. S.
2016-01-01
We present a brief review of the reaction mechanisms involved in collisions of weakly bound projectiles with tightly bound targets, at near-barrier energies. We discuss systematic behaviors of the data, with emphasis in fusion, breakup, nucleon transfer and elastic scattering. The dependence of the breakup cross section on the charge and mass of the target is discussed, and the influence of the breakup channel on complete fusion is investigated. For this purpose, we compare reduced fusion cross sections with a benchmark universal curve. The behaviors observed in the comparisons are explained in terms of polarization potentials and of nucleon transfer followed by breakup. The influence of the breakup process on elastic scattering is also discussed. Some apparent contradictions between results of different authors are explained and some perspectives of the field are presented. (author)
Weak pion production from nuclei
Indian Academy of Sciences (India)
effect of Pauli blocking, Fermi motion and renormalization of weak ∆ properties ... Furthermore, the angular distribution and the energy distribution of ... Here ψα(p ) and u(p) are the Rarita Schwinger and Dirac spinors for ∆ and nucleon.
International Nuclear Information System (INIS)
Oset, E.; Cabrera, D.; Li, Q.B.; Magas, V.K.; Vicente Vacas, M.J.
2005-01-01
We study the binding energy and the width of the Θ + in nuclei, associated to the KN and KπN components. The first one leads to negligible contributions while the second one leads to a sizeable attraction, enough to bind the Θ + in nuclei. Pauli blocking and binding effects on the KN decay reduce considerably the Θ + decay width in nuclei and medium effects associated to the KπN component also lead to a very small width, as a consequence of which one finds separation between the bound levels considerably larger than the width of the states
Shell closures, loosely bound structures, and halos in exotic nuclei
International Nuclear Information System (INIS)
Saxena, G.; Singh, D.
2013-01-01
Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.
Shell closures, loosely bound structures, and halos in exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Saxena, G., E-mail: gauravphy@gmail.com [Govt. Women Engineering College, Department of Physics (India); Singh, D. [University of Rajasthan, Department of Physics (India)
2013-04-15
Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.
Collisional properties of weakly bound heteronuclear dimers
Marcelis, B.; Kokkelmans, S.J.J.M.F.; Shlyapnikov, G.V.; Petrov, D.S.
2008-01-01
We consider collisional properties of weakly bound heteronuclear molecules (dimers) formed in a two-species mixture of atoms with a large mass difference. We focus on dimers containing light fermionic atoms as they manifest collisional stability due to an effective dimer-dimer repulsion originating
Bound states in weakly disordered spin ladders
Energy Technology Data Exchange (ETDEWEB)
Arlego, M. [Departamento de Fisica, Universidad Nacional de La Plata, CC 67 (1900) La Plata (Argentina)]. E-mail: arlego@venus.fisica.unlp.edu.ar; Brenig, W. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Cabra, D.C. [Laboratoire de Physique Theorique, Universite Louis Pasteur Strasbourg (France); Heidrich-Meisner, F. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Honecker, A. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Rossini, G. [Departamento de Fisica, Universidad Nacional de La Plata, CC 67 (1900) La Plata (Argentina)
2005-04-30
We study the appearance of bound states in the spin gap of spin-12 ladders induced by weak bond disorder. Starting from the strong-coupling limit, i.e., the limit of weakly coupled dimers, we perform a projection on the single-triplet subspace and derive the position of bound states for the single impurity problem of one modified coupling as well as for small impurity clusters. The case of a finite concentration of impurities is treated with the coherent-potential approximation (CPA) in the strong-coupling limit and compared with numerical results. Further, we analyze the details in the structure of the density of states and relate their origin to the influence of impurity clusters.
Fusion, reaction and break-up cross sections of weakly bound projectiles on 64Zn
International Nuclear Information System (INIS)
Gomes, P.R.S.; Padron, I.; Rodriguez, M.D.; Marti, G.V.; Anjos, R.M.; Lubian, J.; Veiga, R.; Liguori Neto, R.; Crema, E.; Added, N.; Chamon, L.C.; Fernandez Niello, J.O.; Capurro, O.A.; Pacheco, A.J.; Testoni, J.E.; Abriola, D.; Arazi, A.; Ramirez, M.; Hussein, M.S.
2004-01-01
We present new measurements and a general discussion of the behavior of the fusion, break-up and reaction cross sections of different projectiles on the same target 64 Zn, at near and above barrier energies. The projectiles are the tightly bound 16 O, the stable weakly bound 6 Li, 7 Li and 9 Be and the radioactive very weakly bound 6 He nuclei. We also compare the results with the ones for heavier targets
Mirror energy difference and the structure of loosely bound proton-rich nuclei around A =20
Yuan, Cenxi; Qi, Chong; Xu, Furong; Suzuki, Toshio; Otsuka, Takaharu
2014-04-01
The properties of loosely bound proton-rich nuclei around A =20 are investigated within the framework of the nuclear shell model. In these nuclei, the strength of the effective interactions involving the loosely bound proton s1/2 orbit is significantly reduced in comparison with that of those in their mirror nuclei. We evaluate the reduction of the effective interaction by calculating the monopole-based-universal interaction (VMU) in the Woods-Saxon basis. The shell-model Hamiltonian in the sd shell, such as USD, can thus be modified to reproduce the binding energies and energy levels of the weakly bound proton-rich nuclei around A =20. The effect of the reduction of the effective interaction on the structure and decay properties of these nuclei is also discussed.
Energy Technology Data Exchange (ETDEWEB)
Lapoux, V
2005-09-15
Information on the structure, spectroscopy and target interaction potentials of exotic nuclei can be inferred by interpreting measured data from direct reactions on proton such as elastic or inelastic scattering of proton (p,p') or one-nucleon transfer reaction (p,d). A series of experimental results has been obtained at the GANIL facilities on the setting composed of the MUST telescope array used for the detection of light charged-particles and of CATS beam detectors. This setting aims at measuring reactions on light proton or deuteron targets through reverse kinematics. Particularly, results on C{sup 10}, C{sup 11} and on direct reactions with the He{sup 8} beam of Spiral are presented. The first chapter is dedicated to the description of the most important theories concerning the nucleus. The experimental tools used to probe the nucleus are reported in the second chapter. The third and fourth chapters present the framework that has allowed us to analyse results from (p,p') and (p,d) reactions on weakly bound exotic nuclei. The last chapter is dedicated to the description of future experimental programs. (A.C.)
Structure and dynamics of weakly bound complexes
International Nuclear Information System (INIS)
Skouteris, D.
1998-01-01
The present thesis deals with the spectroscopic and theoretical investigation of weakly bound complexes involving a methane molecule. Studies of these Van der Waals complexes can give valuable information on the relevant intermolecular dynamics and promote the understanding of the interactions between molecules (which can ultimately lead to chemical reactions). Especially interesting are complexes involving molecules of high symmetry (e.g. tetrahedral, such as methane) because of the unusual effects arising from it (selection rules, nuclear Spin statistical weights etc.). The infrared spectrum of the Van der Waals complex between a CH 4 and a N 2 O molecule has been recorded and most of it has been assigned in the region of the N - O stretch (approximately 2225.0 cm -1 ). Despite the fact that this is really a weakly bound complex, it is nevertheless rigid enough so that the standard model for asymmetric top spectra can be applied to it with the usual quantum numbers. From the value of the inertial defect, it turns out that the methane unit is locked in a rigid configuration within the complex rather than freely rotating. The intermolecular distance as well as the tilting angle of the N 2 O linear unit are determined from the rotational constants. The complex itself turns out to have a T - shaped configuration. The infrared spectrum of the Ar - CH 4 complex at the ν 4 (bending) band of methane is also assigned. This is different from the previous one in that the methane unit rotates almost freely Within the complex. As a result, the quantum numbers used to classify rovibrational energy levels include these of the free unit. The concept of 'overall symmetry' is made use of to rationalise selection rules in various sub-bands of the spectrum. Moreover, new terms in the potential anisotropy Hamiltonian are calculated through the use of the overall symmetry concept. These are termed 'mixed anisotropy' terms since they involve both rotational and vibrational degrees of
Directory of Open Access Journals (Sweden)
Oyelami, Benjamin Oyediran
2013-09-01
Full Text Available In this paper, criteria for the existence of weak solutions and uniformly weak bounded solution of impulsive heat equation containing maximum temperature are investigated and results obtained. An example is given for heat flow system with impulsive temperature using maximum temperature simulator and criteria for the uniformly weak bounded of solutions of the system are obtained.
'Critical' behaviour of weakly bound systems
International Nuclear Information System (INIS)
Lassaut, M.; Lombard, R.J.; Bulboaca, I.
1995-11-01
The class of 3-dimensional finite range or similar potentials λW(r) is discussed, depending on a strength constant λ. The behaviour of the eigenvalue E as function of λ-λ c is studied, where λ c is the critical value at the transition from 0 → 1 bound state. For the l=0 case, E α (λ-λ c ) 2 was found, whereas the relationship is linear for l≥1. Treating l as a continuous parameter in the radial Schroedinger equation, the evolution of the power-law between l=0 and l=1 is given. Besides spherically symmetric scalar potentials, the case of a repulsive scalar potential combined with a spin-orbit component of the Thomas form is also discussed. (author)
Electron Capture Dissociation of Weakly Bound Polypeptide Polycationic Complexes
DEFF Research Database (Denmark)
Haselmann, Kim F; Jørgensen, Thomas J D; Budnik, Bogdan A
2002-01-01
as well as specific complexes of modified glycopeptide antibiotics with their target peptide. The weak nature of bonding is substantiated by blackbody infrared dissociation, low-energy collisional excitation and force-field simulations. The results are consistent with a non-ergodic ECD cleavage mechanism.......We have previously reported that, in electron capture dissociation (ECD), rupture of strong intramolecular bonds in weakly bound supramolecular aggregates can proceed without dissociation of weak intermolecular bonds. This is now illustrated on a series of non-specific peptide-peptide dimers...
Faddeev-Yakubovsky technique for weakly bound systems
International Nuclear Information System (INIS)
Hadizadeh, M.R.; Yamashita, M.T.; Tomio, Lauro; Delfino, A.
2011-01-01
Nature shows the existence of weakly bound systems in different sectors, ranging from atomic to nuclear physics. Few-body systems with large scattering length exhibit universal features, which are independent of the details of the interaction, and thus are common to nuclear and atomic systems. Very different methods are used to study the properties of few-body systems, from Faddeev methods to diagonalization methods that rely on an expansion of the wave functions in a complete basis set, like e.g. hyper-spherical harmonics and no core shell model. In this talk we present Faddeev-Yakubovsky method to study the three- and four-body bound states in momentum space. To show the efficiency and accuracy of the method we investigate the three- and four-boson weakly bound states in unitary limit (for zero two-body binding) and we present a pretty complete picture of universality. (author)
An upper bound on right-chiral weak interactions
International Nuclear Information System (INIS)
Stephenson, G.J.; Goldman, T.; Maltman, K.
1990-01-01
Weak vertex corrections to the quark-gluon vertex functions produce differing form-factor corrections for quarks of differing chiralities. These differences grow with increasing four-momentum transfer in the gluon leg. Consequently, inclusive polarized proton--proton scattering to a final state jet should show a large parity-violating asymmetry at high energies. The absence of large signals at sufficiently high energies can be interpreted as being due to balancing vertex corrections from a right-handed weak vector boson of limited mass, and limits on the strength of such signals can, in principle, give upper bounds on that mass. 2 refs
An upper bound on right-Chiral weak interactions
International Nuclear Information System (INIS)
Stephenson, G.J.; Goldman, T.; Maltman, K.
1990-01-01
Weak vertex corrections to the quark-gluon vertex functions produce differing form-factor corrections for quarks of differing chiralities. These differences grow with increasing four-momentum transfer in the gluon leg. Consequently, inclusive polarized proton-proton scattering to a final state jet should show a large parity-violating asymmetry at high energies. The absence of large signals at sufficiently high energies can be interpreted as being due to balancing vertex corrections from a right-handed weak vector boson of limited mass, and limits on the strength of such signals can, in principle, give upper bounds on that mass
The tightly bound nuclei in the liquid drop model
Sree Harsha, N. R.
2018-05-01
In this paper, we shall maximise the binding energy per nucleon function in the semi-empirical mass formula of the liquid drop model of the atomic nuclei to analytically prove that the mean binding energy per nucleon curve has local extrema at A ≈ 58.6960, Z ≈ 26.3908 and at A ≈ 62.0178, Z ≈ 27.7506. The Lagrange method of multipliers is used to arrive at these results, while we have let the values of A and Z take continuous fractional values. The shell model that shows why 62Ni is the most tightly bound nucleus is outlined. A brief account on stellar nucleosynthesis is presented to show why 56Fe is more abundant than 62Ni and 58Fe. We believe that the analytical proof presented in this paper can be a useful tool to the instructors to introduce the nucleus with the highest mean binding energy per nucleon.
Refractive effects in the scattering of loosely bound nuclei
International Nuclear Information System (INIS)
Carstoiu, F.; Trache, L.; Tribble, R.E.; Gagliardi, C.A.; Carstoiu, F.
2004-07-01
A study of the interaction of the loosely bound nuclei 6,7 Li at 9 and 19 MeV/nucleon with light targets has been undertaken. With the determination of unambiguous optical potentials in mind, elastic data for four projectile-target combinations and one neutron transfer reaction 13 C( 7 Li, 8 Li) 12 C have been measured over a large angular range. The kinematical regime encompasses a region where the mean field (optical potential) has a marked variation with mass and energy, but turns out to be sufficiently surface transparent to allow strong refractive effects to be manifested in elastic scattering data at intermediate angles. The identified exotic feature, a 'plateau' in the angular distributions at intermediate angles, is fully confirmed in four reaction channels and is interpreted as a pre-rainbow oscillation resulting from the interference of the barrier and internal barrier far-side scattering sub-amplitudes. (authors)
Classical molecular dynamics simulation of weakly-bound projectile heavy-ion reactions
Directory of Open Access Journals (Sweden)
Morker Mitul R.
2015-01-01
Full Text Available A 3-body classical molecular dynamics approach for heavy-ion reactions involving weakly bound projectiles is developed. In this approach a weakly bound projectile is constructed as a two-body cluster of the constituent tightly bound nuclei in a configuration corresponding to the observed breakup energy. This 3-body system with their individual nucleon configuration in their ground state is dynamically evolved for given initial conditions using the three-stage classical molecular dynamics approach (3S-CMD. Various levels of rigidbody constraints on the projectile constituents and the target are considered at appropriate stages. This 3-dimensional approach explicitly takes into account not only the long range Coulomb reorientation of the deformed collision partner but internal excitations and breakup probabilities at distances close to the barrier also. Dynamical simulations of 6Li+209Bi show all the possible reaction mechanism like complete fusion, incomplete fusion, scattering and breakup scattering. Complete fusion cross sections of 6Li+209Bi and 7Li+209Bi reactions are calculated in this approach with systematic relaxations of the rigid-body constraints on one or more constituent nuclei.
Refractive effects in the scattering of loosely bound nuclei
Energy Technology Data Exchange (ETDEWEB)
Carstoiu, F.; Trache, L.; Tribble, R.E.; Gagliardi, C.A. [Texas A and M Univ., College Station, TX (United States). Cyclotron Inst; Carstoiu, F. [Laboratoire de Physique Corpusculaire, IN2P3-CNRS, ISMRA, Universite de Caen, 14 - Caen (France); Carstoiu, F. [National Institute for Physics and Nuclear Engineering, Horia Hulubei, Bucharest-Magurele (Romania)
2004-07-01
A study of the interaction of the loosely bound nuclei {sup 6,7}Li at 9 and 19 MeV/nucleon with light targets has been undertaken. With the determination of unambiguous optical potentials in mind, elastic data for four projectile-target combinations and one neutron transfer reaction {sup 13}C({sup 7}Li,{sup 8}Li){sup 12}C have been measured over a large angular range. The kinematical regime encompasses a region where the mean field (optical potential) has a marked variation with mass and energy, but turns out to be sufficiently surface transparent to allow strong refractive effects to be manifested in elastic scattering data at intermediate angles. The identified exotic feature, a 'plateau' in the angular distributions at intermediate angles, is fully confirmed in four reaction channels and is interpreted as a pre-rainbow oscillation resulting from the interference of the barrier and internal barrier far-side scattering sub-amplitudes. (authors)
Zhang, G. L.; Zhang, G. X.; Hu, S. P.; Zhang, H. Q.; Gomes, P. R. S.; Lubian, J.; Guo, C. L.; Wu, X. G.; Yang, J. C.; Zheng, Y.; Li, C. B.; He, C. Y.; Zhong, J.; Li, G. S.; Yao, Y. J.; Guo, M. F.; Sun, H. B.; Valiente-Dobòn, J. J.; Goasduff, A.; Siciliano, M.; Galtarosa, F.; Francesco, R.; Testov, D.; Mengoni, D.; Bazzacco, D.; John, P. R.; Qu, W. W.; Wang, F.; Zheng, L.; Yu, L.; Chen, Q. M.; Luo, P. W.; Li, H. W.; Wu, Y. H.; Zhou, W. K.; Zhu, B. J.; Li, E. T.; Hao, X.
2017-11-01
Investigation of the breakup and transfer effect of weakly bound nuclei on the fusion process has been an interesting research topic in the past several years. However, owing to the low intensities of the presently available radioactive ion beam (RIB), it is difficult to clearly explore the reaction mechanisms of nuclear systems with unstable nuclei. In comparison with RIB, the beam intensities of stable weakly bound nuclei such as 6,7Li and 9Be, which have significant breakup probability, are orders of magnitude higher. Precise fusion measurements have already been performed with those stable weakly bound nuclei, and the effect of breakup of those nuclei on the fusion process has been extensively studied. Those nuclei indicated large production cross sections for particles other than the α + x breakup. The particles are originated from non-capture breakup (NCBU), incomplete fusion (ICF) and transfer processes. However, the conclusion of reaction dynamics was not clear and has the contradiction. In our previous experiments we have performed 6Li+96Zr and 154Sm at HI-13 Tandem accelerator of China Institute of Atomic Energy (CIAE) by using HPGe array. It is shown that there is a small complete fusion (CF) suppression on medium-mass target nucleus 96Zr different from about 35% suppression on heavier target nucleus 154Sm at near-barrier energies. It seems that the CF suppression factor depends on the charge of target nuclei. We also observed one neutron transfer process. However, the experimental data are scarce for medium-mass target nuclei. In order to have a proper understanding of the influence of breakup and transfer of weakly bound projectiles on the fusion process, we performed the 6Li+89Y experiment with incident energies of 22 MeV and 34 MeV on Galileo array in cooperation with Si-ball EUCLIDES at Legnaro National Laboratory (LNL) in Italy. Using particle-particle and particle-γ coincidences, the different reaction mechanisms can be clearly explored.
Weakly bound structures in neutron rich Si isotopes
International Nuclear Information System (INIS)
Singh, D.; Saxena, G.; Yadav, H.L.
2009-01-01
Production of radioactive beams have facilitated the nuclear structure studies away from the line of β-stability, especially for the neutron rich drip line nuclei. Theoretical investigations of these nuclei have been carried out by using various approaches viz. few body model or clusters, shell model and mean field theories, both nonrelativistic as well as relativistic mean field (RMF). The advantage of the RMF approach, however, is that in this treatment the spin-orbit interaction is included in a natural way. This is especially advantageous for the description of drip-line nuclei for which the spin-orbit interaction plays an important role. In this communication we report briefly the results of our calculations for the Si isotopes carried out within the framework of RMF + BCS approach
Sharma, Natasha
2016-01-01
The excellent particle identification capabilities of the ALICE detector, using the time projection chamber and the time-of-flight detector, allow the detection of light nuclei and anti-nuclei. Furthermore, the high tracking resolution provided by the inner tracking system enables the separation of primary nuclei from those coming from the decay of heavier systems. This allows for the reconstruction of decays such as the hypertriton mesonic weak decay ($^3_{\\Lambda}$H$\\rightarrow ^3$He + $\\pi^-$), the decay of a hypothetical bound state of a $\\Lambda$n into a deuteron and pion or the H-dibaryon decaying into a $\\Lambda$, a proton and a $\\pi^{-}$. An overview of the production of stable nuclei and anti-nuclei in proton-proton, proton-lead and, in particular, lead-lead collisions is presented. Hypernuclei production rates in Pb--Pb are also shown, together with the upper limits estimated on the production of hypothetical exotica candidates. The results are compared with predictions for the production in thermal...
Electromagnetic and neutral-weak response functions of light nuclei
Lovato, Alessandro
2015-10-01
A major goal of nuclear theory is to understand the strong interaction in nuclei as it manifests itself in terms of two- and many-body forces among the nuclear constituents, the protons and neutrons, and the interactions of these constituents with external electroweak probes via one- and many-body currents. Using imaginary-time projection technique, quantum Monte Carlo allows for solving the time-independent Schrödinger equation even for Hamiltonians including highly spin-isospin dependent two- and three- body forces. I will present a recent Green's function Monte Carlo calculation of the quasi-elastic electroweak response functions in light nuclei, needed to describe electron and neutrino scattering. We found that meson-exchange two-body currents generate excess transverse strength from threshold to the quasielastic to the dip region and beyond. These results challenge the conventional picture of quasi elastic inclusive scattering as being largely dominated by single-nucleon knockout processes. These findings are of particular interest for the interpretation of neutrino oscillation signals.
International Nuclear Information System (INIS)
Han Jianlong; Hu Zhengguo; Zhang Xueyin; Yuan Xiaohua; Xu Huagen; Qi Huirong; Wang Yue; Jia Fei; Wu Lijie; Ding Xianli; Gao Qi; Gao Hui; Bai Zhen
2006-01-01
The differential cross-sections for elastic scattering of 17 F and 17 O on 208 Pb have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles shows clearly that there exists a turning point in the range of small scattering angles (6 degree-20 degree) for 17 F having exotic structure, while no turning point was observed in the 17 O elastic scattering. The experimental results have been compared with previous data. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering differential cross-sections of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the fact that the turning point of the logarithms of differential cross-sections appears at small angle for weakly bound nuclei could be used as a new probe to investigate the halo and skin phenomenon. (authors)
International symposium on weak and electromagnetic interactions in nuclei
International Nuclear Information System (INIS)
Walecka, J.D.
1989-01-01
The purpose of the symposium is to study the implications of the Standard Model (and its extensions) in the realm of low-energy physics. The atomic nucleus constitutes a laboratory where these questions can be investigated. Low and medium-energy accelerators, reactors and other facilities continue to play an important role in this field. The electroweak sector of the Standard Model has benefited much from these investigations. Weak and electromagnetic interactions are also used to probe nuclear and hadronic structures and also new states of nuclear matter (the strong sector of the Standard Model). These studies cannot be dissociated from the fundamental questions raised in the realm of high-energy physics, astrophysics and cosmology. The symposium is therefore intended to be a meeting ground for low, medium-, and high-energy physicists, astrophysicists and cosmologists, who are tackling common problems in many different ways. That is the summary. By now most of the expert speakers have come, given their talks, and left, I assume that those of you who are still here would like to have some framework in which to put the things you have heard in the last week, and in addition gain some perspective on where we are and where we are going. That is what I am going to try and do in this talk
Nuclear structure and weak rates of heavy waiting point nuclei under rp-process conditions
Nabi, Jameel-Un; Böyükata, Mahmut
2017-01-01
The structure and the weak interaction mediated rates of the heavy waiting point (WP) nuclei 80Zr, 84Mo, 88Ru, 92Pd and 96Cd along N = Z line were studied within the interacting boson model-1 (IBM-1) and the proton-neutron quasi-particle random phase approximation (pn-QRPA). The energy levels of the N = Z WP nuclei were calculated by fitting the essential parameters of IBM-1 Hamiltonian and their geometric shapes were predicted by plotting potential energy surfaces (PESs). Half-lives, continuum electron capture rates, positron decay rates, electron capture cross sections of WP nuclei, energy rates of β-delayed protons and their emission probabilities were later calculated using the pn-QRPA. The calculated Gamow-Teller strength distributions were compared with previous calculation. We present positron decay and continuum electron capture rates on these WP nuclei under rp-process conditions using the same model. For the rp-process conditions, the calculated total weak rates are twice the Skyrme HF+BCS+QRPA rates for 80Zr. For remaining nuclei the two calculations compare well. The electron capture rates are significant and compete well with the corresponding positron decay rates under rp-process conditions. The finding of the present study supports that electron capture rates form an integral part of the weak rates under rp-process conditions and has an important role for the nuclear model calculations.
Far-Infrared Spectroscopy of Weakly Bound Hydrated Cluster Molecules
DEFF Research Database (Denmark)
Andersen, Jonas
The thermodynamic properties of condensed phases, the functionality of many materials and the molecular organization in biological organisms are all governed by the classes of non-covalent interactions that occur already on the microscopic scale between pairs of molecules. A detailed investigation...... of the intermolecular interactions between prototypical molecular assemblies are valuable for accurate descriptions of larger supramolecular systems such as materials, gas hydrates and biological macromolecules. The aim of this PhD dissertation is to investigate intermolecular interactions fora series of medium...... vibrational bands of the cluster molecules in the challenging far-infrared and terahertz spectral regions.A key parameter in the validation of the performance of theoretical predictions for weak non-covalent intermolecular interactions is the dissociation energy D0 that depends heavily on the class of large...
Estimation of absorbed dose in cell nuclei due to DNA-bound /sup 3/H
Energy Technology Data Exchange (ETDEWEB)
Saito, M; Ishida, M R; Streffer, C; Molls, M
1985-04-01
The average absorbed dose due to DNA-bound /sup 3/H in a cell nucleus was estimated by a Monte Carlo simulation for a model nucleus which was assumed to be spheroidal. The volume of the cell nucleus was the major dose-determining factor for cell nuclei which have the same DNA content and the same specific activity of DNA. This result was applied to estimating the accumulated dose in the cell nuclei of organs of young mice born from mother mice which ingested /sup 3/H-thymidine with drinking water during pregnancy. The values of dose-modifying factors for the accumulated dose due to DNA-bound /sup 3/H compared to the dose due to an assumed homogenous distribution of /sup 3/H in organ were found to be between about 2 and 6 for the various organs.
Bounds on the Capacity of Weakly constrained two-dimensional Codes
DEFF Research Database (Denmark)
Forchhammer, Søren
2002-01-01
Upper and lower bounds are presented for the capacity of weakly constrained two-dimensional codes. The maximum entropy is calculated for two simple models of 2-D codes constraining the probability of neighboring 1s as an example. For given models of the coded data, upper and lower bounds...... on the capacity for 2-D channel models based on occurrences of neighboring 1s are considered....
Parity violation in nuclei: studies of the weak nucleon-nucleon interaction
International Nuclear Information System (INIS)
Mcdonald, A.B.
1980-03-01
The Weinberg-Salam Unified Model of weak and electromagnetic interactions has been very successful in explaining parity violation and neutral current effects in neutrino-nucleon, electron-nucleon and neutrino-electron interactions. A wide variety of nuclear physics parity violation experiments are in progress to measure effects of the weak nucleon-nucleon interaction in few nucleon systems and certain heavier nuclei where enhancements are expected. The current status of these experiments will be reviewed, including details of an experiment at Chalk River to search for parity violation in the photodisintegration of deuterium and an extension of our previous measurements of parity mixing in 21 Ne. The interpretation of results in terms of basic models of the weak interaction will be discussed. (Auth)
International Nuclear Information System (INIS)
O’Carroll, Michael
2012-01-01
We consider the interaction of particles in weakly correlated lattice quantum field theories. In the imaginary time functional integral formulation of these theories there is a relative coordinate lattice Schroedinger operator H which approximately describes the interaction of these particles. Scalar and vector spin, QCD and Gross-Neveu models are included in these theories. In the weakly correlated regime H=H o +W where H o =−γΔ l , 0 l is the d-dimensional lattice Laplacian: γ=β, the inverse temperature for spin systems and γ=κ 3 where κ is the hopping parameter for QCD. W is a self-adjoint potential operator which may have non-local contributions but obeys the bound ‖W(x, y)‖⩽cexp ( −a(‖x‖+‖y‖)), a large: exp−a=β/β o (1/2) (κ/κ o ) for spin (QCD) models. H o , W, and H act in l 2 (Z d ), d⩾ 1. The spectrum of H below zero is known to be discrete and we obtain bounds on the number of states below zero. This number depends on the short range properties of W, i.e., the long range tail does not increase the number of states.
Semileptonic weak and electromagnetic interactions in nuclei: recoil polarization in muon capture
International Nuclear Information System (INIS)
Rosenfelder, R.
1979-01-01
An analysis of the polarization of the recoiling nucleus following the capture of polarized muons by nuclei is performed. New general expressions for arbitrary nuclear spin are obtained in terms of the same reduced matrix elements which govern inelastic electron scattering and β-decay. As an application the A = 12 system is considered and uncertainties in the nuclear structure are studied by using different sets of one-body density matrices. With the canonical values of the weak form factors (i.e. absence of second-class currents) a fairly good agreement with the experimental data is achieved including the inelastic form factor at high momentum transfers and the recently measured average 12 B polarization. Implications of the new corrected value of the average polarization on weak form factors and nuclear structure are discussed. (Auth.)
Interpretation of quasi-elastic barrier distributions for weakly bound systems
International Nuclear Information System (INIS)
Monteiro, D.S.; Gomes, P.R.S.; Lubian, J.
2009-01-01
Full text: We verify that quasi-elastic (elastic + inelastic) backscattering barrier distributions for weakly bound systems do not strictly correspond to fusion barrier distributions, but rather to reaction threshold distribution, as proposed by Zagrebaev in a recent paper concerning very heavy systems. In this work, we investigate whether Zagrebaevs interpretation is valid by comparing experimental results obtained in two very recent works with the 6 Li + 144 Sm system. Monteiro et al derived the quasi-elastic barrier distribution (or reaction threshold distribution, following Zagrebaevs interpretation) by adding elastic and inelastic backscattering for this system. Rath et al obtained fusion barrier distribution for the same system from the measured complete fusion cross section for the same system. We conclude that the quasi-elastic barrier distributions can be associated with fusion barrier distributions only in situations where there are no relevant reaction channels apart from fusion. This is not the situation for very heavy nor for weakly bound systems. (author)
Detailed determination of the fusion nuclear radius in reactions involving weakly bound projectiles
International Nuclear Information System (INIS)
Gomez Camacho, A.; Aguilera, E. F.; Quiroz, E. M.
2007-01-01
A detailed determination of the fusion radius parameter is performed within the Distorted Wave Born Approximation for reactions involving weakly bound projectiles. Specifically, a simultaneous X 2- analysis of elastic and fusion cross section data is done using a Woods-Saxon potential with volume and surface parts. The volume part is assumed to be responsible for fusion reactions while the surface part for all other direct reactions. It is proved that in order to fit fusion data, particularly for energies below the Coulomb barrier where fusion is enhanced, it is necessary to have a value of around 1.4 fm for the fusion radial parameter of the fusion potential (W F ). This value is much higher than that frequently used in Barrier Penetration models (1.0 fm). The calculations are performed for reactions involving the weakly bound projectile 9 Be with several medium mass targets. (Author)
Short versus long range interactions and the size of two-body weakly bound objects
International Nuclear Information System (INIS)
Lombard, R.J.; Volpe, C.
2003-01-01
Very weakly bound systems may manifest intriguing ''universal'' properties, independent of the specific interaction which keeps the system bound. An interesting example is given by relations between the size of the system and the separation energy, or scaling laws. So far, scaling laws have been investigated for short-range and long-range (repulsive) potentials. We report here on scaling laws for weakly bound two-body systems valid for a larger class of potentials, i.e. short-range potentials having a repulsive core and long-range attractive potentials. We emphasize analogies and differences between the short- and the long-range case. In particular, we show that the emergence of halos is a threshold phenomenon which can arise when the system is bound not only by short-range interactions but also by long-range ones, and this for any value of the orbital angular momentum l. These results enlarge the image of halo systems we are accustomed to. (orig.)
Weak interactions and exchange currents in light nuclei. Theoretical and experimental aspects
International Nuclear Information System (INIS)
Guichon, P.
1980-01-01
The influence of meson exchange currents in the nuclear weak interaction is investigated theoretically and experimentally. The hypothesis of current algebra and partial conservation of axial current are used, through Adler-Dothan theorem, to derive the one pion exchange correction to the impulse approximation. Calculations are performed for partial transitions in the 1p-shell nuclei and in 16 O. The corrections are generally small except for the (0 + →0 - ) transition in 16 O where the large correction to the time component of the axial current can show up, due to selection rules. The measurement of the muon capture rate for this transition is described and an interpretation in term of exchange currents is proposed [fr
International Nuclear Information System (INIS)
Lin, C.J.; Zhang, H.Q.; Yang, F.; Ruan, M.; Liu, Z.H.; Wu, Y.W.; Wu, X.K.; Zhou, P.; Zhang, C.L.; Zhang, G.L.; An, G.P.; Jia, H.M.; Xu, X.X.
2007-01-01
The excitation functions of quasielastic and elastic scattering at backward angles have been measured for the systems of 16 O+ 152 Sm, 6,7 Li+ 208 Pb and 32 S+ 90,96 Zr. The barrier distributions are extracted from these measured excitation functions and compared with the corresponding fusion barrier distributions. Except some details, the barrier distributions derived from the data of fusion and quasielastic/elastic scattering are almost the same for the tightly bound reaction systems. For the reaction systems with weakly bound projectile, the barrier distributions extracted from quasielastic scattering are obviously different from the fusion barrier distributions. However, the barrier distributions extracted from the excitation functions of the quasielastic scattering plus breakup are almost the same as the one extracted from the complete fusion data. This result means that barrier distribution not only bears the information of nuclear structures but also contains the knowledge of reaction mechanisms. Our results show that the complete fusion of the weakly bound projectile with heavy target is suppressed at the above barrier energies as compared with the model predictions. In addition, the measured barrier distribution of 32 S+ 96 Zr is broaden and extends to lower energy than in the case of 32 S+ 90 Zr due to the coupling of neutron transfer with positive Q-values, which result in a significant enhancement of fusion cross sections at the subbarrier energies
Bounds on graviton mass using weak lensing and SZ effect in galaxy clusters
Rana, Akshay; Jain, Deepak; Mahajan, Shobhit; Mukherjee, Amitabha
2018-06-01
In General Relativity (GR), the graviton is massless. However, a common feature in several theoretical alternatives of GR is a non-zero mass for the graviton. These theories can be described as massive gravity theories. Despite many theoretical complexities in these theories, on phenomenological grounds the implications of massive gravity have been widely used to put bounds on graviton mass. One of the generic implications of giving a mass to the graviton is that the gravitational potential will follow a Yukawa-like fall off. We use this feature of massive gravity theories to probe the mass of graviton by using the largest gravitationally bound objects, namely galaxy clusters. In this work, we use the mass estimates of galaxy clusters measured at various cosmologically defined radial distances measured via weak lensing (WL) and Sunyaev-Zel'dovich (SZ) effect. We also use the model independent values of Hubble parameter H (z) smoothed by a non-parametric method, Gaussian process. Within 1σ confidence region, we obtain the mass of graviton mg 6.82 Mpc from weak lensing and mg 5.012 Mpc from SZ effect. This analysis improves the upper bound on graviton mass obtained earlier from galaxy clusters.
Solar-bound weakly interacting massive particles a no-frills phenomenology
Collar, J I
1999-01-01
The case for a stable population of solar-bound Earth-crossing Weakly Interacting Massive Particles (WIMPs) is reviewed. A practical general expression for their speed distribution in the laboratory frame is derived under basic assumptions. If such a population exists -even with a conservative phase-space density-, the next generation of large-mass, low-threshold underground bolometers should bring about a sizable enhancement in WIMP sensitivity. Finally, a characteristic yearly modulation in their recoil signal, arising from the ellipticity of the Earth's orbit, is presented.
Investigation of large α production in reactions involving weakly bound 7Li
Pandit, S. K.; Shrivastava, A.; Mahata, K.; Parkar, V. V.; Palit, R.; Keeley, N.; Rout, P. C.; Kumar, A.; Ramachandran, K.; Bhattacharyya, S.; Nanal, V.; Palshetkar, C. S.; Nag, T. N.; Gupta, Shilpi; Biswas, S.; Saha, S.; Sethi, J.; Singh, P.; Chatterjee, A.; Kailas, S.
2017-10-01
The origin of the large α -particle production cross sections in systems involving weakly bound 7Li projectiles has been investigated by measuring the cross sections of all possible fragment-capture as well as complete fusion using the particle-γ coincidence, in-beam, and off-beam γ -ray counting techniques for the 7Li+93Nb system at near Coulomb barrier energies. Almost all of the inclusive α -particle yield has been accounted for. While the t -capture mechanism is found to be dominant (˜70 % ), compound nuclear evaporation and breakup processes contribute ˜15 % each to the inclusive α -particle production in the measured energy range. Systematic behavior of the t capture and inclusive α cross sections for reactions involving 7Li over a wide mass range is also reported.
Rotational spectrum and structure of the carbonyl sulfide-trifluoromethane weakly bound dimer.
Serafin, Michal M; Peebles, Sean A
2006-11-02
Pure rotational spectra of five isotopomers of the 1:1 weakly bound complex formed between carbonyl sulfide and trifluoromethane (TFM) have been measured using Fourier transform microwave spectroscopy. The experimental rotational constants and dipole moment components are consistent with a structure of C(s) symmetry in which the dipole moment vectors of OCS and HCF(3) are aligned antiparallel and at an angle of about 40 degrees and with a center of mass separation of 3.965(26) A. The derived H...O distance is 2.90(5) A, which is up to 0.6 A longer than is seen in other similar TFM complexes exhibiting C-H...O interactions. Ab initio calculations at the MP2/6-311++G(2d,2p) level give a structure with rotational constants that are in reasonable agreement with those of the normal isotopic species.
Classical treatments of quantum mechanical effects in collisions of weakly bound complexes
International Nuclear Information System (INIS)
Lopez, Jose G.; McCoy, Anne B.
2005-01-01
Classical and quantum simulations of Ne + Ar 2 collision dynamics are performed in order to investigate where quantum mechanical effects are most important and where classical simulations provide good descriptions of the dynamics. It is found that when Ar 2 is in a low-lying vibrational state, the differences between the results of quantum and quasiclassical simulations are profound. However, excellent agreement between the results of the quantum and classical simulations can be achieved when the initial conditions for the classical trajectories are sampled from the quantum phase space distribution given by the Wigner function. These effects are largest when collisions occur under constrained geometries or when Ar 2 is in its ground vibrational state. The results of this work suggest that sampling the initial conditions using the Wigner function provides a straightforward way to incorporate the most important quantum mechanical effects in simulations of collisions involving very cold weakly bound complexes
Interplay of break-up and transfer processes in reactions involving weakly-bound systems
Vitturi, Andrea; Moschini, Laura
2018-02-01
In this note we illustrate some applications of a simple model which has been devised to clarify the reaction mechanism and the interplay of different reaction channels (elastic, inelastic, transfer, break-up) in heavy-ion collisions. The model involves two potential wells moving in one dimension and few active particles; in spite of its simplicity, it is supposed to maintain the main features, the properties and the physics of the full three-dimensional case. Special attention is given to the role of continuum states in reactions involving weakly-bound systems, and different approximation schemes (as first-order or coupled-channels) as well as different continuum discretization procedures are tested. In the case of two active particles the reaction mechanism associated with two-particle transfer and the effect of pairing intearction are investigated. Work done in collaboration with Antonio Moro and Kouichi Hagino
Directory of Open Access Journals (Sweden)
Sukjung Hwang
2015-11-01
Full Text Available Here we generalize quasilinear parabolic p-Laplacian type equations to obtain the prototype equation $$ u_t - \\hbox{div} \\Big(\\frac{g(|Du|}{|Du|} Du\\Big = 0, $$ where g is a nonnegative, increasing, and continuous function trapped in between two power functions $|Du|^{g_0 -1}$ and $|Du|^{g_1 -1}$ with $1
Hyperaccretion during Tidal Disruption Events: Weakly Bound Debris Envelopes and Jets
Coughlin, Eric R.; Begelman, Mitchell C.
2014-02-01
After the destruction of the star during a tidal disruption event (TDE), the cataclysmic encounter between a star and the supermassive black hole (SMBH) of a galaxy, approximately half of the original stellar debris falls back onto the hole at a rate that can initially exceed the Eddington limit by orders of magnitude. We argue that the angular momentum of this matter is too low to allow it to attain a disk-like configuration with accretion proceeding at a mildly super-Eddington rate, the excess energy being carried away by a combination of radiative losses and radially distributed winds. Instead, we propose that the infalling gas traps accretion energy until it inflates into a weakly bound, quasi-spherical structure with gas extending nearly to the poles. We study the structure and evolution of such "zero-Bernoulli accretion" flows as a model for the super-Eddington phase of TDEs. We argue that such flows cannot stop extremely super-Eddington accretion from occurring, and that once the envelope is maximally inflated, any excess accretion energy escapes through the poles in the form of powerful jets. We compare the predictions of our model to Swift J1644+57, the putative super-Eddington TDE, and show that it can qualitatively reproduce some of its observed features. Similar models, including self-gravity, could be applicable to gamma-ray bursts from collapsars and the growth of SMBH seeds inside quasi-stars.
Hyperaccretion during tidal disruption events: Weakly bound debris envelopes and jets
Energy Technology Data Exchange (ETDEWEB)
Coughlin, Eric R.; Begelman, Mitchell C., E-mail: eric.coughlin@colorado.edu, E-mail: mitch@jila.colorado.edu [Also at Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 391, Boulder, CO 80309, USA. (United States)
2014-02-01
After the destruction of the star during a tidal disruption event (TDE), the cataclysmic encounter between a star and the supermassive black hole (SMBH) of a galaxy, approximately half of the original stellar debris falls back onto the hole at a rate that can initially exceed the Eddington limit by orders of magnitude. We argue that the angular momentum of this matter is too low to allow it to attain a disk-like configuration with accretion proceeding at a mildly super-Eddington rate, the excess energy being carried away by a combination of radiative losses and radially distributed winds. Instead, we propose that the infalling gas traps accretion energy until it inflates into a weakly bound, quasi-spherical structure with gas extending nearly to the poles. We study the structure and evolution of such 'zero-Bernoulli accretion' flows as a model for the super-Eddington phase of TDEs. We argue that such flows cannot stop extremely super-Eddington accretion from occurring, and that once the envelope is maximally inflated, any excess accretion energy escapes through the poles in the form of powerful jets. We compare the predictions of our model to Swift J1644+57, the putative super-Eddington TDE, and show that it can qualitatively reproduce some of its observed features. Similar models, including self-gravity, could be applicable to gamma-ray bursts from collapsars and the growth of SMBH seeds inside quasi-stars.
Hyperaccretion during tidal disruption events: Weakly bound debris envelopes and jets
International Nuclear Information System (INIS)
Coughlin, Eric R.; Begelman, Mitchell C.
2014-01-01
After the destruction of the star during a tidal disruption event (TDE), the cataclysmic encounter between a star and the supermassive black hole (SMBH) of a galaxy, approximately half of the original stellar debris falls back onto the hole at a rate that can initially exceed the Eddington limit by orders of magnitude. We argue that the angular momentum of this matter is too low to allow it to attain a disk-like configuration with accretion proceeding at a mildly super-Eddington rate, the excess energy being carried away by a combination of radiative losses and radially distributed winds. Instead, we propose that the infalling gas traps accretion energy until it inflates into a weakly bound, quasi-spherical structure with gas extending nearly to the poles. We study the structure and evolution of such 'zero-Bernoulli accretion' flows as a model for the super-Eddington phase of TDEs. We argue that such flows cannot stop extremely super-Eddington accretion from occurring, and that once the envelope is maximally inflated, any excess accretion energy escapes through the poles in the form of powerful jets. We compare the predictions of our model to Swift J1644+57, the putative super-Eddington TDE, and show that it can qualitatively reproduce some of its observed features. Similar models, including self-gravity, could be applicable to gamma-ray bursts from collapsars and the growth of SMBH seeds inside quasi-stars.
Directory of Open Access Journals (Sweden)
Minkov N.
2016-01-01
Full Text Available We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.
A search for bound states of the /eta/-meson in light nuclei
International Nuclear Information System (INIS)
Pile, P.H.
1988-01-01
This paper describes an experiment designed to search for a new form of nuclear matter--a bound /eta/-nucleus system. The (π + ,p) reaction was used to study the possible formation of an /eta/-mesic nucleus. No narrow /eta/-nuclear bound states were observed using 7 Li, 12 C, 16 O and 27 Al targets. 7 refs., 4 figs., 1 tab
International Nuclear Information System (INIS)
Rana, Mukhtar Ahmed; Sher, Gul; Manzoor, Shahid; Shahzad, M. I.
2011-01-01
Fission cross-sections of 119 Sn and 209 Bi induced by negative pions of two energies 500 and 672 MeV were measured using a CR-39 nuclear track detector. Target-detector stacks were exposed to pion beams at the Brookhaven National Laboratory (USA). Measurement results are compared with the corresponding calculations using the computer code CEM95. Agreement between measurements and calculations is fairly good for the 209 Bi target nuclei whereas it is poor for 119 Sn at both investigated energies of 500 and 672 MeV. Fission cross-section results of 119 Sn and 209 Bi are explained using the equilibrium properties of these nuclides including nuclear electric quadrupole moments which determine the shapes of nuclei. A logarithmic dependence of fission cross-section on Z 2 /A is observed for the above-mentioned reactions and a critical limit of Z 2 /A is identified with the value of 30 which divides the curve of σ f versus Z 2 /A into two regimes, one with weak dependence and the other with strong dependence. (nuclear physics)
Mukhtar, Ahmed Rana; Gul, Sher; Shahid, Manzoor; I. Shahzad, M.
2011-09-01
Fission cross-sections of 119Sn and 209Bi induced by negative pions of two energies 500 and 672 MeV were measured using a CR-39 nuclear track detector. Target-detector stacks were exposed to pion beams at the Brookhaven National Laboratory (USA). Measurement results are compared with the corresponding calculations using the computer code CEM95. Agreement between measurements and calculations is fairly good for the 209Bi target nuclei whereas it is poor for 119Sn at both investigated energies of 500 and 672 MeV. Fission cross-section results of 119Sn and 209Bi are explained using the equilibrium properties of these nuclides including nuclear electric quadrupole moments which determine the shapes of nuclei. A logarithmic dependence of fission cross-section on Z2/A is observed for the above-mentioned reactions and a critical limit of Z2/A is identified with the value of 30 which divides the curve of σf versus Z2/A into two regimes, one with weak dependence and the other with strong dependence.
International Nuclear Information System (INIS)
Figueira, J.M.; Abriola, D.; Niello, J.O. Fernandez; Arazi, A.; Capurro, O.A.; Barbara, E. de; Marti, G.V.; Martinez Heimann, D.; Pacheco, A.J.; Testoni, J.E.; Padron, I.; Gomes, P.R.S.; Lubian, J.
2006-01-01
To study the conditions leading to the appearance of the threshold anomaly in systems involving weakly bound projectiles we measured elastic scattering cross sections for the 7 Li+ 27 Al system at ten different bombarding energies. The results were exhaustively analyzed using different optical model potentials. The similar behavior observed in all these analyses allows us to conclude that no threshold anomaly is found for the present system
Directory of Open Access Journals (Sweden)
Zhang G. L.
2017-01-01
In order to have a proper understanding of the influence of breakup and transfer of weakly bound projectiles on the fusion process, we performed the 6Li+89Y experiment with incident energies of 22 MeV and 34 MeV on Galileo array in cooperation with Si-ball EUCLIDES at Legnaro National Laboratory (LNL in Italy. Using particle-particle and particle-γ coincidences, the different reaction mechanisms can be clearly explored.
Weak interaction rates for Kr and Sr waiting-point nuclei under rp-process conditions
International Nuclear Information System (INIS)
Sarriguren, P.
2009-01-01
Weak interaction rates are studied in neutron deficient Kr and Sr waiting-point isotopes in ranges of densities and temperatures relevant for the rp process. The nuclear structure is described within a microscopic model (deformed QRPA) that reproduces not only the half-lives but also the Gamow-Teller strength distributions recently measured. The various sensitivities of the decay rates to both density and temperature are discussed. Continuum electron capture is shown to contribute significantly to the weak rates at rp-process conditions.
International Nuclear Information System (INIS)
Almaliev, A.N.; Batkin, I.S.; Kopytin, I.V.
1987-01-01
The process of exciting atoms and atomic nuclei by relativistic electrons and positrons bound in a one-dimensional potential is investigated theoretically. It is shown that a pole corresponding to the emergence of a virtual photon on a bulk surface occurs in the matrix interaction element under definite kinematic relationships. It is obtained that the probability of the excitation process depends on the lifetime of the level being excited, the virtual photon, and the charged particle in a definite energetic state. An estimate of the magnitude of the excitation section of low-lying nuclear states yields a value exceeding by several orders the section obtained for charged particles in the absence of a binding potential
International Nuclear Information System (INIS)
Kamanin, V.V.; Karamyan, S.A.
1980-01-01
A possibility to obtain parameters of nuclear temperature and critical angular momentum for the compound nucleus production on the base of the (HI, xn) reaction excitation function description are considered for the case of weakly fissioning nuclei. Experimental data on 152 Sm( 12 C, 2n) 162 Er, 148 Nd( 16 O, 3n) 161 Er, sup(150)Nd(sup(16)O, 3-5n)sup(163-161)Er, sup(148)Nd(sup(18)O, 4-5n)sup(162,161)Er, sup(118)Sn(sup(40)Ar, 5-6n)sup(153,152)Er and sup(74)Ge(sup(84)Kr, 5-6n)sup(153,152)Er reactions are discussed. The formulae, taking into accout the distribution of compound nuclei in angular momentum and competition between channels of the neutron and γ-ray emission, are given. The formulae are applied for the description of the excitation functions, characterized by a good accuracy of the particle energy measuring. A satisfactory accordance between the calculation and experiment is achieved. The conclusion on sensitivity of the nuclear temperature values to exact evaluation of competition between the neutron and γ-ray emission channels is drawn
Detection of the weak γ activities from new neutron-rich nuclei
International Nuclear Information System (INIS)
Zhang Li; Wang Jicheng; Zhao Jinhua; Yang Yongfeng; Zheng Jiwen; Hu Qingyuan; Guo Tianrui
2003-01-01
Energic signals of γ rays detected by a HPGe γ detector were coincided with γ-ray, energy-loss signals detected by a 4πΔEβ detector. Then the coinciding β-ray spectra was anticoincided with timing logical signals of 511 keV γ ray created in positron annihilate, detected by a large BGO detector. This special coincidence-anticoincidence system has played an important role in the first observation of the new neutron-rich nuclide 209 Hg. It is shown that this is an effective method to detecting very weak γ-ray activities of neutron-rich isotope in an element-separation sample
Diffraction scattering and disintegration of 3He nuclei by atomic nuclei
International Nuclear Information System (INIS)
Koval'chuk, V.I.
2006-01-01
Within diffraction model framework a method of cross sections calculation for scattering and disintegration of weakly-bounded two-clustered nuclei by nuclei when both of its clusters are changed has been proposed. The experimental elastic scattering cross sections of 3 He by 40 Ca, 90 Zr and coincidence spectra of disintegration products from 28 Si( 3 He,dp) have been described
International Nuclear Information System (INIS)
Flambaum, V.V.; Gribakin, G.F.
1994-01-01
Weak perturbations can be strongly enhanced in many-body systems that have dense spectra of excited states (compound nuclei, rare-earth atoms, molecules, clusters, quantum dots, etc.). Statistical consideration shows that in the case of zero-width states the probability distribution for the effect of the perturbation has an infinitte variance and does not obey the standard central limit theorem, i.e., the probability density for the average effect X=1/n tsum i=1 n x i does not tend to a Gaussian (normal) distribution with variance σ n =σ 1 / √n , where n is the ''number of measurements.'' Since for probability densities of this form [f(x)congruent a/x 2 at large x] the central limit theorem is F n (X)=a/X 2 +π 2 a 2 at n much-gt 1, the breadth of the distribution does not decrease with the increase of n. This means the following. (1) In spite of the random signs of observable effects for different compound states the probability of finding a large average effect for n levels is the same as that for a single-resonance measurements. (2) In some cases one does not need to resolve individual compound resonances and the enhanced value of the effect can be observed in the integral spectrum. This substantially increases the chances to observe statistical enhancement of weak perturbations in different reactions and systems. (3) The average value of parity and time-nonconserving effects in low-energy nucleon scattering cannot be described by a smooth weak optical potential. This ''potential'' would randomly fluctuate as a function of energy, with typical magnitudes much larger than the nucleon-nucleus weak potential. The effect of finite compound-state widths is considered
Near- and subbarrier elastic and quasielastic scattering of the weakly bound 6Li projectile on 144Sm
International Nuclear Information System (INIS)
Monteiro, D. S.; Otomar, D. R.; Lubian, J.; Gomes, P. R. S.; Capurro, O. A.; Marti, G. V.; Arazi, A.; Figueira, J. M.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Niello, J. O. Fernandez; Guimaraes, V.
2009-01-01
High-precision data of backward-angle elastic and quasielastic scattering for the weakly bound 6 Li projectile on 144 Sm target at deep-sub-barrier, near-, and above-barrier energies were measured. From the deep-sub-barrier data, the surface diffuseness of the nuclear interacting potential was studied. Barrier distributions were extracted from the first derivatives of the elastic and quasielastic excitation functions. It is shown that sequential breakup through the first resonant state of the 6 Li is an important channel to be included in coupled-channels calculations, even at deep-sub-barrier energies
Dynamics of fragment capture for cluster structures of weakly bound 7Li
Directory of Open Access Journals (Sweden)
Shrivastava A.
2013-12-01
Full Text Available Role of cluster structures of 7Li on reaction dynamics have been studied by performing exclusive measurements of prompt-γ rays from residues with scattered particles at energy, E/Vb = 1.6, with 198Pt target. Yields of the residues resulting after capture of t and 4,5,6He, corresponding to different excitation energies of the composite system were estimated. The results were compared with three body classical-dynamical model for breakup fusion, constrained by the measured fusion, α and t capture cross-sections. The cross-section of residues from capture of α and t agreed well with the prediction of the model showing dominance of the two step process - breakup fusion, while those from tightly bound 6He showed massive transfer to be the dominant mechanism.
Interfacial behavior of polar, weakly polar, and nonpolar compounds bound to activated carbons.
Gun'ko, V M; Turov, V V; Zarko, V I; Goncharuk, O V; Nychiporuk, Yu M; Kozynchenko, O P; Skubiszewska-Zięba, J; Leboda, R; Charmas, B; Balakin, D Yu; Ptushinskii, Yu G
2013-08-15
Detailed analysis of the interfacial behavior of water and weakly polar or nonpolar organics adsorbed alone or co-adsorbed onto activated carbons (AC) at different temperatures is a complex problem important for practical applications of adsorbents. Interaction of water, 1-decanol, and n-decane with AC possessing highly developed porosity (pore volume Vp≈1.4-2.3 cm(3)/g, specific surface area S(BET)≈1500-3500 m(2)/g) was studied over a broad temperature range using differential scanning calorimetry (DSC), thermoporometry, (1)H NMR spectroscopy, cryoporometry, and temperature-programmed desorption with mass-spectrometry control methods. Comparison of the pore size distributions (PSD) calculated using the DSC thermoporometry, NMR cryoporometry, and nitrogen adsorption isotherms allows us to determine localization of adsorbates in different pores, as well as changes in the PSD of AC due to freezing of adsorbates in pores. Theoretical calculations (using ab initio HF/6-31G(d,p), DFT B3LYP/6-31G(d,p), and PM7 methods) explain certain aspects of the interfacial behavior of water, decane, and decanol adsorbed onto AC that appear in the experimental data. Obtained results show strong temperature dependence (above and below the freezing point, Tf, of bulk liquids) of the interfacial behavior of adsorbates on the textural characteristics and hydrophilic/hydrophobic properties of AC and the adsorbate amounts that affect the distributions of adsorbates unfrozen at T
Projectile fragmentation of a weakly-bound 11Be nucleus at 0.8 GeV/nucleon
International Nuclear Information System (INIS)
Kobayashi, T.
1990-01-01
The projectile fragmentation of a weakly-bound 11 Be projectile has been measured on a carbon target at 0.8 GeV/nucleon. The transverse momentum distribution of 10 Be fragments showed a two-Gaussian structure: a narrow component with σ ∼ 25 MeV/c on top of a wide component with σ ∼ 110 MeV/c. As in the case of 11 Li fragmentation, the narrow momentum distribution indicates a long tail in the neutron density distribution which is consistent with the large nuclear matter radius of the 11 Be nucleus. Neutrons were also measured in coincidence with 10 Be fragments. In contrast to 10 Be fragments, no narrow momentum distribution was observed for coincident neutrons
International Nuclear Information System (INIS)
Zhukov, V.V.; Osovskij, V.D.; Ptushnikov, Yu.G.; Sukretnyj, V.G.; Chujkov, B.A.
1986-01-01
A molecular beam technique with an effusion source operating at T=200 K is used to study the adsorption interaction of oxygen with W(100) and (110) faces in the range of the simple temperatures from 5 to 340 K. Three weakly-bound adsorption states of oxygen are detected corresponding to adsorption in the second, third and forth monolayer. These states are characterized by adsorption energies of 0.13, 0.08 and 0.07 eV and desorption temperatures of 45, 27 and 25 K, respectively. The kinetics of filling of these states is almost similar for both faces, whereas the adsorption kinetics in the first monolayer is essentially different. A dissociative nature of adsorption at T >or approx. 5 K and a jump migration mechanism of the admolecules in the precursor state to the stationary adsorption sites are suggested
Energy Technology Data Exchange (ETDEWEB)
Roncaratti, L. F., E-mail: lz@fis.unb.br; Leal, L. A.; Silva, G. M. de [Instituto de Física, Universidade de Brasília, 70910 Brasília (Brazil); Pirani, F. [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Aquilanti, V. [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Instituto de Física, Universidade Federal da Bahia, 40210 Salvador (Brazil); Gargano, R. [Instituto de Física, Universidade de Brasília, 70910 Brasília (Brazil); Departments of Chemistry and Physics, University of Florida, Quantum Theory Project, Gainesville, Florida 32611 (United States)
2014-10-07
We consider the analytical representation of the potential energy surfaces of relevance for the intermolecular dynamics of weakly bound complexes of chiral molecules. In this paper we study the H{sub 2}O{sub 2}−Ng (Ng=He, Ne, Ar, Kr, and Xe) systems providing the radial and the angular dependence of the potential energy surface on the relative position of the Ng atom. We accomplish this by introducing an analytical representation which is able to fit the ab initio energies of these complexes in a wide range of geometries. Our analysis sheds light on the role that the enantiomeric forms and the symmetry of the H{sub 2}O{sub 2} molecule play on the resulting barriers and equilibrium geometries. The proposed theoretical framework is useful to study the dynamics of the H{sub 2}O{sub 2} molecule, or other systems involving O–O and S–S bonds, interacting by non-covalent forces with atoms or molecules and to understand how the relative orientation of the O–H bonds changes along collisional events that may lead to a hydrogen bond formation or even to selectivity in chemical reactions.
International Nuclear Information System (INIS)
Lepailleur, Alexandre
2013-01-01
Nuclear forces play a decisive role to account for the evolution of the nuclear structure and to fix the limits of particle stability. The study of neutron-rich nuclei is particularly important to determine these limits and to reveal the disappearance or emergence of new shell gaps far from stability. We studied the weakly bound neutron-rich 26 F in order to probe the πd 5/2 xνd 3/2 interaction. Indeed this nucleus can be modeled as a closed core of 24 O on top of which a single deeply bound proton in πd 5/2 interacts with an unbound neutron in νd 3/2 . This coupling gives rise to the quadruplet of states J = 1, 2, 3, 4 of positive parity. Their determination would allow us to quantify the intensity of the πd 5/2 xνd 3/2 interaction. Among these states, the J = 1 (ground state) and J = 2 (first excited state) were already known. The search for the J = 4 state has been investigated by our group at GANIL through a β-decay experiment. The nuclei of 26 F were produced by the fragmentation of a 36 S beam and selected using the LISE spectrometer. They were then implanted in a Double Sided Stripped Silicon Detector that gave us the opportunity to achieve spatial and time correlations between the implanted ions and the products of the decays (β and γ rays). Moreover we were able to observe the delayed M3 γ transition from the isomeric J = 4 state to the J = 1 ground state and thus obtained the excitation energy of 643.4 keV for this isomeric state. We also determined several new states in 25-26 Ne that were fed by the β-decay of the ground and isomeric state of 26 F. We extracted an isomeric ratio of about 40% and adjusted the previously determined mass of 26 F according to this value, leading to ΔM = 270 (50) keV. The J = 3 state has been populated ad studied at GSI by means of a one proton knock-out reaction from a radioactive 27 Ne beam to produce the 26 F in its unbound states. When the 26 F is produced in its unbound state J = 3, it decays in 25 F + n. The
International Nuclear Information System (INIS)
Goble, J.H. Jr.
1982-05-01
Three variations on the Dunham series expansion function of the potential of a diatomic molecule are compared. The differences among these expansions lie in the choice of the expansion variable, lambda. The functional form of these variables are lambda/sub s/ = l-r/sub e//r for the Simon-Parr-Finlan version, lambda/sub T/ - 1-(r/sub e//r)/sup p/ for that of Thakkar, and lambda/sub H/ = 1-exp(-rho(r/r/sub e/-1) for that of Huffaker. A wide selection of molecular systems are examined. It is found that, for potentials in excess of thirty kcal/mole, the Huffaker expansion provides the best description of the three, extrapolating at large internuclear separation to a value within 10% of the true dissociation energy. For potentials that result from the interaction of excited states, all series expansions show poor behavior away from the equilibrium internuclear separation of the molecule. The series representation of the potentials of weakly bound molecules are examined in more detail. The ground states of BeAr + , HeNe + , NaAr, and Ar 2 and the excited states of HeNe+, NaNe, and NaAr are best described by the Thakkar expansion. Finally, the observation of laser-assisted excitive Penning ionization in a flowing afterglow is reported. The reaction Ar( 3 P 2 ) + Ca + h nu → Ar + Ca + (5p 2 P/sub J/) + e - occurs when the photon energy, h nu, is approximately equal to the energy difference between the metastable argon and one of the fine structure levels of the ion's doublet. By monitoring the cascade fluorescence of the above reaction and comparing it to the flourescence from the field-free process Ar( 3 P 2 ) + Ca → Ar + Ca + (4p 2 P/sub J/) + e - a surprisingly large cross section of 6.7 x 10 3 A 2 is estimated
Li, H.; Roux, S. J.
1992-01-01
A casein kinase II (CK II)-like protein kinase was identified and partially isolated from a purified envelope-matrix fraction of pea (Pisum sativum L.) nuclei. When [gamma-32P]ATP was directly added to the envelope-matrix preparation, the three most heavily labeled protein bands had molecular masses near 71, 48, and 46 kDa. Protein kinases were removed from the preparation by sequential extraction with Triton X-100, EGTA, 0.3 M NaCl, and a pH 10.5 buffer, but an active kinase still remained bound to the remaining lamina-matrix fraction after these treatments. This kinase had properties resembling CK II kinases previously characterized from animal and plant sources: it preferred casein as an artificial substrate, could use GTP as efficiently as ATP as the phosphoryl donor, was stimulated by spermine, was calcium independent, and had a catalytic subunit of 36 kDa. Some animal and plant CK II kinases have regulatory subunits near 29 kDa, and a lamina-matrix-bound protein of this molecular mass was recognized on immunoblot by anti-Drosophila CK II polyclonal antibodies. Also found associated with the envelope-matrix fraction of pea nuclei were p34cdc2-like and Ca(2+)-dependent protein kinases, but their properties could not account for the protein kinase activity bound to the lamina. The 71-kDa substrate of the CK II-like kinase was lamin A-like, both in its molecular mass and in its cross-reactivity with anti-intermediate filament antibodies. Lamin phosphorylation is considered a crucial early step in the entry of cells into mitosis, so lamina-bound CK II kinases may be important control points for cellular proliferation.
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1991-02-01
Many studies published in the past are reviewed first in relation to high-resolution spectroscopy of deeply-bound pionic atoms in heavy nuclei. The report then describes a procedure for applying the method of inverse kinematics to the case of (d, 3 He) reactions. The (d, 3 He) reaction in inverse kinematics is feasible from practical viewpoints. Thus a discussion is made of the inverse kinematics in which a heavy-ion beam ( 208 Pb for instance) with a projectile kinetic energy hits a deuteron target and ejected recoil 3 He nuclei are measured in the forward direction. The recoil momentum is calculated as a function of the Q value. Analysis shows that the recoil spectroscopy with inverse kinematics can be applied to the case of (d, 3 He) reaction, which will yield a very high mass resolution. The experimental setup for use in the first stage is then outlined, and a simple detector configuration free of magnetic field is discussed. These investigations demonstrate that the (d, 3 He) reaction in inverse kinematics provides a promising tool for obtaining high-resolution spectra of deeply-bound pionic atoms. (N.K.)
Energy Technology Data Exchange (ETDEWEB)
Goble, J.H. Jr.
1982-05-01
Three variations on the Dunham series expansion function of the potential of a diatomic molecule are compared. The differences among these expansions lie in the choice of the expansion variable, lambda. The functional form of these variables are lambda/sub s/ = l-r/sub e//r for the Simon-Parr-Finlan version, lambda/sub T/ - 1-(r/sub e//r)/sup p/ for that of Thakkar, and lambda/sub H/ = 1-exp(-rho(r/r/sub e/-1) for that of Huffaker. A wide selection of molecular systems are examined. It is found that, for potentials in excess of thirty kcal/mole, the Huffaker expansion provides the best description of the three, extrapolating at large internuclear separation to a value within 10% of the true dissociation energy. For potentials that result from the interaction of excited states, all series expansions show poor behavior away from the equilibrium internuclear separation of the molecule. The series representation of the potentials of weakly bound molecules are examined in more detail. The ground states of BeAr/sup +/, HeNe/sup +/, NaAr, and Ar/sub 2/ and the excited states of HeNe+, NaNe, and NaAr are best described by the Thakkar expansion. Finally, the observation of laser-assisted excitive Penning ionization in a flowing afterglow is reported. The reaction Ar(/sup 3/P/sub 2/) + Ca + h nu ..-->.. Ar + Ca/sup +/(5p /sup 2/P/sub J/) + e/sup -/ occurs when the photon energy, h nu, is approximately equal to the energy difference between the metastable argon and one of the fine structure levels of the ion's doublet. By monitoring the cascade fluorescence of the above reaction and comparing it to the flourescence from the field-free process Ar(/sup 3/P/sub 2/) + Ca ..-->.. Ar + Ca/sup +/(4p /sup 2/P/sub J/) + e/sup -/ a surprisingly large cross section of 6.7 x 10/sup 3/ A/sup 2/ is estimated.
International Nuclear Information System (INIS)
Toki, Hiroshi; Yamazaki, Toshimitsu
1989-01-01
The standard method of pionic atom formation does not produce deeply bound pionic atoms. A study is made on the properties of deeply bound pionic atom states by using the standard pion-nucleus optical potential. Another study is made to estimate the cross sections of the formation of ls pionic atom states by various methods. The pion-nucleus optical potential is determined by weakly bound pionic atom states and pion nucleus scattering. Although this potential may not be valid for deeply bound pionic atoms, it should provide some hint on binding energies and level widths of deeply bound states. The width of the ls state comes out to be 0.3 MeV and is well separated from the rest. The charge dependence of the ls state is investigated. The binding energies and the widths increase linearly with Z azbove a Z of 30. The report then discusses various methods to populate deeply bound pionic atoms. In particular, 'pion exchange' reactions are proposed. (n, pπ) reaction is discussed first. The cross section is calculated by assuming the in- and out-going nucleons on-shell and the produced pion in (n1) pionic atom states. Then, (n, dπ - ) cross sections are estimated. (p, 2 Heπ - ) reaction would have cross sections similar to the cross section of (n, dπ - ) reaction. In conclusion, it seems best to do (n, p) experiment on heavy nuclei for deeply bound pionic atom. (Nogami, K.)
Population of Nuclei Via 7Li-Induced Binary Reactions
International Nuclear Information System (INIS)
Clark, Rodney M.; Phair, Larry W.; Descovich, M.; Cromaz, Mario; Deleplanque, M.A.; Fall on, Paul; Lee, I-Yang; Macchiavelli, A.O.; McMahan, Margaret A.; Moretto, Luciano G.; Rodriguez-Vieitez, E.; Sinha, Shrabani; Stephens, Frank S.; Ward, David; Wiedeking, Mathis
2005-01-01
The authors have investigated the population of nuclei formed in binary reactions involving 7 Li beams on targets of 160 Gd and 184 W. The 7 Li + 184 W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si ΔE-E telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczynski binary transfer model, in combination with a standard evaporation model, they are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies
Neutron halo in deformed nuclei
International Nuclear Information System (INIS)
Zhou Shangui; Meng Jie; Ring, P.; Zhao Enguang
2010-01-01
Halo phenomena in deformed nuclei are investigated within a deformed relativistic Hartree Bogoliubov (DRHB) theory. These weakly bound quantum systems present interesting examples for the study of the interdependence between the deformation of the core and the particles in the halo. Contributions of the halo, deformation effects, and large spatial extensions of these systems are described in a fully self-consistent way by the DRHB equations in a spherical Woods-Saxon basis with the proper asymptotic behavior at a large distance from the nuclear center. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nucleus 44 Mg. The core of this nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the occurrence of this decoupling effects are discussed.
Weak radiative decays of the B meson and bounds on M{sub H}± in the Two-Higgs-Doublet Model
Energy Technology Data Exchange (ETDEWEB)
Misiak, Mikolaj [University of Warsaw, Faculty of Physics, Institute of Theoretical Physics, Warsaw (Poland); CERN, Theoretical Physics Department, Geneva 23 (Switzerland); Steinhauser, Matthias [Karlsruhe Institute of Technology (KIT), Institut fuer Theoretische Teilchenphysik, Karlsruhe (Germany)
2017-03-15
In a recent publication (Abdesselam et al. arXiv:1608.02344), the Belle collaboration updated their analysis of the inclusive weak radiative B-meson decay, including the full dataset of (772 ± 11) x 10{sup 6} B anti B pairs. Their result for the branching ratio is now below the Standard Model prediction (Misiak et al. Phys Rev Lett 114:221801, 2015, Czakon et al. JHEP 1504:168, 2015), though it remains consistent with it. However, bounds on the charged Higgs boson mass in the Two-Higgs-Doublet Model get affected in a significant manner. In the so-called Model II, the 95% C.L. lower bound on M{sub H}± is now in the 570-800 GeV range, depending quite sensitively on the method applied for its determination. Our present note is devoted to presenting and discussing the updated bounds, as well as to clarifying several ambiguities that one might encounter in evaluating them. One of such ambiguities stems from the photon energy cutoff choice, which deserves re-consideration in view of the improved experimental accuracy. (orig.)
Classical simulations of heavy-ion fusion reactions and weakly
Indian Academy of Sciences (India)
2014-04-30
Apr 30, 2014 ... Heavy-ion collision simulations in various classical models are discussed. ... are also simulated in a 3-stage classical molecular dynamics (3S-CMD) ... considered as a weakly-bound cluster of deuteron and 4He nuclei, thus, ...
International Nuclear Information System (INIS)
Woon, D.E.; Peterson, K.A.; Dunning, T.H. Jr.
1998-01-01
The interaction of Ar with H 2 and HCl has been studied using Moeller - Plesset perturbation theory (MP2, MP3, MP4) and coupled-cluster [CCSD, CCSD(T)] methods with augmented correlation consistent basis sets. Basis sets as large as triply augmented quadruple zeta quality were used to investigate the convergence trends. Interaction energies were determined using the supermolecule approach with the counterpoise correction to account for basis set superposition error. Comparison with the available empirical potentials finds excellent agreement for both binding energies and transition state. For Ar - H 2 , the estimated complete basis set (CBS) limits for the binding energies of the two equivalent minima and the connecting transition state (TS) are, respectively, 55 and 47cm -1 at the MP4 level and 54 and 46cm -1 at the CCSD(T) level, respectively [the XC(fit) empirical potential of Bissonnette et al. [J. Chem. Phys. 105, 2639 (1996)] yields 56.6 and 47.8cm -1 for H 2 (v=0)]. The estimated CBS limits for the binding energies of the two minima and transition state of Ar - HCl are 185, 155, and 109cm -1 at the MP4 level and 176, 147, and 105cm -1 at the CCSD(T) level, respectively [the H6(4,3,0) empirical potential of Hutson [J. Phys. Chem. 96, 4237 (1992)] yields 176.0, 148.3, and 103.3cm -1 for HCl (v=0)]. Basis sets containing diffuse functions of (dfg) symmetries were found to be essential for accurately modeling these two complexes, which are largely bound by dispersion and induction forces. Highly correlated wave functions were also required for accurate results. This was found to be particularly true for ArHCl, where significant differences in calculated binding energies were observed between MP2, MP4, and CCSD(T). copyright 1998 American Institute of Physics
Energy Technology Data Exchange (ETDEWEB)
Trabelsi, T.; Ajili, Y.; Ben Yaghlane, S.; Jaidane, N.-E. [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications–LSAMA, Université de Tunis El Manar, Tunis (Tunisia); Mogren Al-Mogren, M. [Chemistry Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Francisco, J. S. [Department of Chemistry and Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47906 (United States); Hochlaf, M., E-mail: hochlaf@univ-mlv.fr [Laboratoire Modélisation et Simulation Multi Echelle, Université Paris-Est, MSME UMR 8208 CNRS, 5 Blvd. Descartes, 77454 Marne-la-Vallée (France)
2015-07-21
We investigate the lowest electronic states of doublet and quartet spin multiplicity states of HNS{sup −} and HSN{sup −} together with their parent neutral triatomic molecules. Computations were performed using highly accurate ab initio methods with a large basis set. One-dimensional cuts of the full-dimensional potential energy surfaces (PESs) along the interatomic distances and bending angle are presented for each isomer. Results show that the ground anionic states are stable with respect to the electron detachment process and that the long range parts of the PESs correlating to the SH{sup −} + N, SN{sup −} + H, SN + H{sup −}, NH + S{sup −}, and NH{sup −} + S are bound. In addition, we predict the existence of long-lived weakly bound anionic complexes that can be formed after cold collisions between SN{sup −} and H or SH{sup −} and N. The implications for the reactivity of these species are discussed; specifically, it is shown that the reactions involving SH{sup −}, SN{sup −}, and NH{sup −} lead either to the formation of HNS{sup −} or HSN{sup −} in their electronic ground states or to autodetachment processes. Thus, providing an explanation for why the anions, SH{sup −}, SN{sup −}, and NH{sup −}, have limiting detectability in astrophysical media despite the observation of their corresponding neutral species. In a biological context, we suggest that HSN{sup −} and HNS{sup −} should be incorporated into H{sub 2}S-assisted heme-catalyzed reduction mechanism of nitrites in vivo.
DEFF Research Database (Denmark)
Severin, Gregory; Jørgensen, Jesper T.; Wiehr, Stefan
2015-01-01
free or weakly bound 89Zr released in circulation. 89Zr oxalate had the desired characteristics, and was injected into mice bearing FaDu and HT29 solid tumor xenografts, and mice infected in the lungs with the mold Aspergillus fumigatus, as well as in healthy controls (naïve). PET/CT and PET/MR imaging...... followed to quantify the distribution of the radionuclide in the disease models. Results 89Zr oxalate was found to have a plasma half-life of 5.1 ± 2.3 h, accumulating mainly in the bones of all animals. Both tumor types accumulated 89Zr on the order of 2-4% ID/cm3, which is comparable to EPR...... in the disease sites in the present study, we recommend control experiments mapping the biodistribution of free 89Zr in any preclinical study employing 89Zr where bone uptake is observed. Aqueous 89Zr oxalate appears to be a suitable compound for such studies. This is especially relevant in studies where...
International Nuclear Information System (INIS)
Bjorken, J.D.
1978-01-01
Weak interactions are studied from a phenomenological point of view, by using a minimal number of theoretical hypotheses. Charged-current phenomenology, and then neutral-current phenomenology are discussed. This all is described in terms of a global SU(2) symmetry plus an electromagnetic correction. The intermediate-boson hypothesis is introduced and lower bounds on the range of the weak force are inferred. This phenomenology does not yet reconstruct all the predictions of the conventional SU(2)xU(1) gauge theory. To do that requires an additional assumption of restoration of SU(2) symmetry at asymptotic energies
Exploring the Physics of Unstable Nuclei
Volya, Alexander
In this presentation the Continuum Shell Model (CSM) approach is advertised as a powerful theoretical tool for studying physics of unstable nuclei. The approach is illustrated using 17O as an example, which is followed by a brief presentation of the general CSM formalism. The successes of the CSM are highlighted and references are provided throughout the text. As an example, the CSM is applied perturbatively to 20O allowing one to explore the effects of continuum on positions of weakly bound states and low-lying resonances, as well as to discern some effects of threshold discontinuity.
Exploring the physics of unstable nuclei
International Nuclear Information System (INIS)
Volya, Alexander
2015-01-01
In this presentation the Continuum Shell Model (CSM) approach is advertised as a powerful theoretical tool for studying physics of unstable nuclei. The approach is illustrated using 17 O as an example, which is followed by a brief presentation of the general CSM formalism. The successes of the CSM are highlighted and references are provided throughout the text. As an example, the CSM is applied perturbatively to 20 O allowing one to explore the effects of continuum on positions of weakly bound states and low-lying resonances, as well as to discern some effects of threshold discontinuity. (author)
International Nuclear Information System (INIS)
Jager, H.U.; Kirchbach, M.; Truhlik, E.
1982-01-01
Starting with the hard pion model based on a minimal chiral invariant phenomenological Lagrangian, the two-particle part of the time component of the weak axial-vector current is constructed in the tree-approximation. Pion, rho- and A 1 -meson exchanges are considered. The mesonic exchange operator obtained is applied to describe the purely weak axial 0 + reversible 0 - , ΔT=1 transition in the nuclear A=16 system the muon reaction μ - + 16 O(0 1 + ; T=0) → 16 N(0 1 - ; T=1) + γsub(μ) and beta decay 16 N(0 1 - ; T=1) → 16 O(0 1 + ; T=0) + e - + anti νsub(e). In order to treat nufar structure correlation efects explicit use of shell model wave functions with configuration mixing is made. The large enhancement of the nuclear weak axial charge density with respect to impulse approximation is established
International Nuclear Information System (INIS)
Scharff-Goldhaber, G.
1979-01-01
It was shown previously that, below a critical angular momentum, yrast bands of nonmagic nuclei are well described by the two-parameter variable moment of inertia model. Some striking exceptions to this rule are found in nuclei which have the same mass number as doubly magic nuclei but possess either one (or two) proton pairs beyond a magic number and one (or two) neutron hole pairs, or vice versa. Yrast bands in these pseudomagic nuclei resemble those in magic nuclei. 17 references
International Nuclear Information System (INIS)
Hodgson, P.E.
1990-01-01
The effects of nucleon clustering in nuclei are described, with reference to both nuclear structure and nuclear reactions, and the advantages of using the cluster formalism to describe a range of phenomena are discussed. It is shown that bound and scattering alpha-particle states can be described in a unified way using an energy-dependent alpha-nucleus potential. (author)
International Nuclear Information System (INIS)
Willner, K.
2006-01-01
A Mapped Fourier Grid method for solving the radial Schroedinger equation is improved. It is observed that a discrete sine and cosine transform algorithm allows to compute a Hamiltonian matrix the spectrum of which is free of spurious eigenvalues. - The energies of the highest, least bound vibrational states of the Na - Na 2 van der Waals complex are computed using a hyperspherical diabatic-by-sector method. The computed levels are analyzed using quantum defect theory. (orig.)
Chiavazza, Enrico; Kubala, Eugen; Gringeri, Concetta V; Düwel, Stephan; Durst, Markus; Schulte, Rolf F; Menzel, Marion I
2013-02-01
Scalar coupling relaxation, which is usually only associated with closely resonant nuclei (e.g., (79)Br-(13)C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-(13)C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T(1) shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar (14)N adjacent to the (13)C nucleus in the amide group. This contribution is only effective in low magnetic fields (i.e., less than 800 μT) and prevents the use of molecules bearing the (13)C-amide group as hyperpolarized MRS/MRI probes. In the present work, this hypothesis is explored both theoretically and experimentally. The results show that high hyperpolarization levels can be retained using either a (15)N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner. Copyright © 2012 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Shimizu, Yoshifumi
2009-01-01
Except for the closed shell nuclei, almost all nuclei are in the superconducting state at their ground states. This well-known pair correlation in nuclei causes various interesting phenomena. It is especially to be noted that the pair correlation becomes weak in the excited states of nuclei with high angular momentum, which leads to the pair phase transition to the normal state in the high spin limit. On the other hand, the pair correlation becomes stronger in the nuclei with lower nucleon density than in those with normal density. In the region of neutron halo or skin state of unstable nuclei, this phenomenon is expected to be further enhanced to be observed compared to the ground state of stable nuclei. An overview of those interesting aspects caused via the pair correlation is presented here in the sections titled 'pair correlations in ground states', pair correlations in high spin states' and 'pair correlations in unstable nuclei' focusing on the high spin state. (S. Funahashi)
Reactions with fast radioactive beams of neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Aumann, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)
2005-11-01
The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like {sup 11}Li and {sup 12}Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)
Reactions with fast radioactive beams of neutron-rich nuclei
International Nuclear Information System (INIS)
Aumann, T.
2005-11-01
The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like 11 Li and 12 Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)
An upper bound on Q-star masses
International Nuclear Information System (INIS)
Hochron, D.R.; Selipsky, S.B.
1992-06-01
Q-stars (the gravitational generalization of Q-balls, strongly bound bulk matter that an appear in field theories of strongly interacting hadrons) are the only known impact objects consistent with the known bulk structure of nuclei and chiral symmetry that evade the Rhoades-Ruffini upper bound of 3.2M circle-dot . Generic bounds are quite weak: M Q-star circle-dot . If, however, we assume that the 1.558 ms pulsar is a Q-star, equilibrium. A stability criteria of rotating fluids place a much stronger upper bound of M c ≤ 5.3M circle-dot on such models under certain special assumptions. This has important implications for heavy compact objects such as Cygnus X-1
International Nuclear Information System (INIS)
Anon.
1995-01-01
The recent detection of intergalactic helium by NASA's Astro-2 mission backs up two earlier measurements by ESA and the University of California, San Diego, using instruments aboard the Hubble Space Telescope. Taken together, these results give strong evidence that this helium is primordial, confirming a key prediction of the Big Bang theory. The amount of helium the results imply could also account for some of the Universe's invisible dark matter - material which affects galactic motion but is otherwise undetectable. According to theory, helium nuclei formed at around 100 seconds after the Big Bang, but the amount of helium depended on even earlier events. Initially, protons turned into neutrons with the same probability that neutrons turned into protons. But after about one second, the Universe had cooled down enough for the weak interaction to freeze out. Neutrons continued to decay into the slightly lighter protons, whilst the opposite reaction became much more scarce. At around 100 seconds, thermonuclear fusion reactions could begin, and all the neutrons that were left became absorbed into helium nuclei, leaving the remaining protons locked up in hydrogen. The ratio of helium to hydrogen was therefore determined by events occurring when the Universe was just one second old. Standard models of primordial nucleosynthesis fix this ratio at slightly less than 2 5% by mass. All heavier elements were cooked up much later in the stars, and amount to less than 1 % of the Universe's mass. These predictions have been borne out remarkably well by observation, although proof of the primordial origins of hydrogen and helium has remained elusive until now. Big Bang nucleosynthesis goes on to estimate that primordial baryonic matter in the form of light nuclei could account for around 10% of the Universe's dark matter. All three recent measurements used the same technique of looking at distant quasars, some of the most luminous objects in the Universe, to
Electroweak interactions in nuclei
International Nuclear Information System (INIS)
Henley, E.M.
1984-06-01
Topics include: introduction to electroweak theory; the Weinberg-Salam theory for leptons; the Weinberg-Salam theory for hadrons-the GIM mechanism; electron scattering as a probe of the electroweak interaction (observation of PV, the weak interaction for nucleons, and parity violation in atoms); and time reversed invariance and electric dipole moments of nucleons, nuclei, and atoms. 52 references
International Nuclear Information System (INIS)
Sydorenko, D.; Smolyakov, A.; Kaganovich, I.; Raitses, Y.
2009-01-01
A new regime of plasma-wall interaction is identified in particle-in-cell simulations of a hot plasma bounded by walls with secondary electron emission. Such a plasma has a strongly non-Maxwellian electron velocity distribution function and consists of bulk plasma electrons and beams of secondary electrons. In the new regime, the plasma sheath is not in a steady space charge limited state even though the secondary electron emission produced by the plasma bulk electrons is so intense that the corresponding partial emission coefficient exceeds unity. Instead, the plasma-sheath system performs relaxation oscillations by switching quasiperiodically between the space charge limited and non-space-charge limited states.
Reaction Mechanism and Structure Interplay for Proton Elastic Scattering from Halo Nuclei
International Nuclear Information System (INIS)
Crespo, R.; Johnson, R.C.
1999-01-01
The aim of this work is to clarify what properties of the projectile w.f. are relevant to describe elastic scattering of halo nuclei from stable nuclei. In particular, we examine how far elastic scattering observables probe correlation effects among projectile nucleons. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of 11 Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering cross sections can not, in general, be deduced from knowledge of the total matter density alone. We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead
Reaction mechanism and structure interplay for proton elastic scattering from halo nuclei
International Nuclear Information System (INIS)
Crespo, R.; Johnson, R. C.
1999-01-01
The aim of this work is to clarify what properties of the projectile w.f. are relevant to describe elastic scattering of halo nuclei from stable nuclei. In particular, we examine how far elastic scattering observables probe correlation effects among projectile nucleons. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of 11 Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering crosssections cannot, in general, be deduced from knowledge of the total matter density alone. We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead
International Nuclear Information System (INIS)
Villari, A.C.C.
1990-01-01
The actual tendencies to study exotic nuclei; applications of exotic nuclei beams in material study and medicine; recent results obtained by GANIL and Berkeley Laboratories of measurements of binding energy and radii of light nuclei; the future experiences to be carry out in several international laboratories and; proposal of studies in Brazil using Pelletron-USP accelerator and the LINAC superconductor accelerator, in construction in the same laboratory, are presented. (M.C.K.)
The quest for novel modes of excitation in exotic nuclei
Paar, N.
2010-06-01
This paper provides an insight into several open problems in the quest for novel modes of excitation in nuclei with isospin asymmetry, deformation and finite-temperature characteristics in stellar environments. Major unsolved problems include the nature of pygmy dipole resonances, the quest for various multipole and spin-isospin excitations both in neutron-rich and proton drip-line nuclei mainly driven by loosely bound nucleons, excitations in unstable deformed nuclei and evolution of their properties with the shape phase transition. Exotic modes of excitation in nuclei at finite temperatures characteristic of supernova evolution present open problems with a possible impact in modeling astrophysically relevant weak interaction rates. All these issues challenge self-consistent many-body theory frameworks at the frontiers of on-going research, including nuclear energy density functionals, both phenomenological and constrained by the strong interaction physics of QCD, models based on low-momentum two-nucleon interaction Vlow-k and correlated realistic nucleon-nucleon interaction VUCOM, supplemented by three-body force, as well as two-nucleon and three-nucleon interactions derived from the chiral effective field theory. Joined theoretical and experimental efforts, including research with radioactive isotope beams, are needed to provide insight into dynamical properties of nuclei away from the valley of stability, involving the interplay of isospin asymmetry, deformation and finite temperature.
International Nuclear Information System (INIS)
Akopyan, M E; Baturo, V V; Lukashov, S S; Poretsky, S A; Pravilov, A M
2013-01-01
The stepwise three-step three-colour aser excitation scheme and rotational as well as rovibrational energy transfer processes in the 0 + g state induced by collisions with He and Ar atoms are used for determination of rovibronic level energies of the weakly bound 0 + g state correlating with the I( 2 P 1/2 ) + I( 2 P 1/2 ) dissociation limit. Dunham coefficients of the state, Y i0 (i = 0–3), Y i1 (i = 0–3) and Y 02 for the v 0 g + = 0–16 and J 0 g + ≈ 14–135 ranges as well as the dissociation energy of the state, D e , and equilibrium I–I distance of the state, R e , are determined. The potential energy curve of the state constructed using these constants is also reported. (paper)
International Nuclear Information System (INIS)
Schramm, D.N.
1995-01-01
Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis reactions involve unstable nuclei. Hence there is a tight relationship hetween the subject of this conference and cosmology. The prime role of unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundances with observed abundances. In general, abundance determinations are dominated by systematic rather than statistical errors, and work on bounding systematics is crucial. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ω b are possible vis-a-vis the homogeneous model; hence the robustness of Ω b ∼0.05 is now apparent. (These calculations depend critically on unstable nuclei.) The above argues that the bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ω b ∼1 seems to be definitely excluded, so if Ω TOTAL =1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In summary, it is argued that the physics of unstable nuclei affects the fundamental dark matter argument. ((orig.))
Are cometary nuclei primordial rubble piles?
Weissman, P. R.
1986-01-01
Whipple's icy conglomerate model for the cometary nucleus has had considerable sucess in explaining a variety of cometary phenomena such as gas production rates and nongravitational forces. However, as discussed here, both observational evidence and theoretical considerations suggest that the cometary nucleus may not be a well-consolidated single body, but may instead be a loosely bound agglomeration of smaller fragments, weakly bonded and subject to occasional or even frequent disruptive events. The proposed model is analogous to the 'rubble pile' model suggested for the larger main-belt asteroids, although the larger cometary fragments are expected to be primordial condensations rather than collisionally derived debris as in the asteroid case. The concept of cometary nuclei as primordial rubble piles is proposed as a modification of the basic Whipple model, not as a replacement for it.
Cavitation inception from bubble nuclei
DEFF Research Database (Denmark)
Mørch, Knud Aage
2015-01-01
, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...
International Nuclear Information System (INIS)
Rho, M.
1981-01-01
Quantum chromodynamics is believed to be candidate theory for the strong interactions and contains as its ingredients spinor quark fields and vector gluons, none of which can perhaps be ever liberated and detected in laboratories. A nucleus consists of nucleons bound by nuclear force which are however separately observable and which seem to preserve their identities even under extreme conditions. An intriguing question is: when compressed to high densities or heated to high temperature, at what point does a nuclear matter cease to be describable in terms of nucleon and meson degrees of freedom, but become a plasma of quarks and gluons; and how does this transition occur. This is not an idle question. If quarks and gluons are never to be observed isolated, then it may be that at low energies (or at low densities) they are not the right variables to do physics with. Instead hadrons must be. On the other hand, asymptotic freedom - the unique property of non-abelian gauge theories to which QCD belongs that quark-gluon and gluon-gluon interactions get weaker at short distances - tells us that at some large matter density the matter must necessarily be in the form of quark gas interacting only weakly. This means that a change in degrees of freedom must take place. We would like to know where this occurs and how. In this talk, I would like to address to this question by discussing first the large success we have had in understanding the role that mesons play in finite nuclei and nuclear matter and then attempting to correlate nucleon and meson degrees of freedom to quark-gluon degrees of freedom. In my opinion we are now at a stage where we feel fairly confident in our understanding of nucleon-meson structure of nuclei and nuclear matter and any further progress in deeper understanding of nuclear dynamics - and strong interactions - must come from QCD or its effective version, bags or strings. (orig.)
Halo structure of strange particles in nuclei
International Nuclear Information System (INIS)
Akaishi, Yoshinori; Yamazaki, Toshimitsu.
1997-01-01
Some characteristic behaviors of hyperons in nuclei which have recently been revealed experimentally and theoretically are discussed with the emphasis on the repulsive part of the hyperon-nucleus interaction. The observed Σ 4 He nucleus is a bound state with J π = 0 + and T ≅ 1/2. Its nucleus-Σ potential derived from a realistic ΣN interaction is characterized by inner repulsion and a strong Lane term, which play important roles in forming the Σ-hypernuclear bound state. In 208 Pb a typical Coulomb-assisted bound state is expected, where Σ is trapped in the surface region by the nucleus-Σ potential with the aid of Coulomb and centrifugal interactions. In the double-strangeness (S=-2) sector, there is a possibility that the lightest double-Λ hypernucleus ΛΛ 4 H is abundantly populated by stopping Ξ - on 4 He. Its formation branching amounts to about 15%. A stopped Ξ - on 9 Be will also produce efficiently a variety of double-Λ hyperfragments. Discrete spectra of weak-decay pions from the fragments will provide a means of mass spectroscopy of double-Λ hypernuclei. In the S=-2 five-body system an excited state Ξ 5 H is predicted to appear with 'strangeness halo' and the ground state ΛΛ 5 H with almost pure ΛΛ component. (author)
Microscopic theory of light exotic nuclei. Shell Models Embedded in the Continuum
International Nuclear Information System (INIS)
Bennaceur, K.
1999-01-01
The recent advances in experimental nuclear physics make it possible to study nuclear systems far from the beta stability line. The discovery of new phenomena, like halos or neutron skins, requires the development of new theoretical models which enable to study these systems. The first part of this work is devoted to the development and the applications of the Shell Model Embedded in the Continuum (SMEC). This new formalism allows to take into account the correlations between the bound and scattering states of loosely bound nuclei. SMEC is applied here to the study of the spectroscopy of the Mirror nuclei 8 B- 8 Li and 17 F- 17 O. It can also be used to calculate the cross sections of the elastic scattering, the Coulomb breakup processes and the radiative n,p capture processes. The results concerning the reactions of astrophysical interest: 18 O(p, γ) 17 F and 7 Be(p, γ) 8 B, are discussed in details. This last reaction is very important because the disintegration of 8 B is the main source of High energy neutrinos in the sun. The second part of this work is related to the analysis of pairing interaction for weakly bound nuclei. We have developed a new approach, based on the Hartree-Fock-Bogolyubov (HFB) theory, that allows to study the pairing correlations between bound and scattering states, both resonant and not resonant ones. The 'particle-hole' potential is replaced by a model potential for which the solutions are analytically known. This method allows to analyse the effect of pairing on bound and resonant states, independently of their energy position. We have clearly demonstrated that the non-resonant continuum plays a crucial role in the loosely bound nuclei and that solving the HFB equations in the coordinate space is the only method that permits to treat this problem correctly. (author)
Elastic scattering, fusion, and breakup of light exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Kolata, J.J. [University of Notre Dame, Physics Department, Notre Dame, IN (United States); Guimaraes, V. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo, SP (Brazil); Aguilera, E.F. [Instituto Nacional de Investigaciones Nucleares, Departamento de Aceleradores, Mexico, Distrito Federal (Mexico)
2016-05-15
The present status of fusion reactions involving light (A< 20) radioactive projectiles at energies around the Coulomb barrier (E<10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron- and proton-rich systems. Possible physical explanations for the observed differences are also reviewed. (orig.)
International Nuclear Information System (INIS)
Akopyan, M E; Baturo, V V; Lukashov, S S; Poretsky, S A; Pravilov, A M
2015-01-01
The stepwise three-step three-color laser population of the I 2 (β1 g , ν β , J β ) rovibronic states via the B0 u + , ν B , J B rovibronic states and rovibronic levels of the 1 u (bb) and 0 g + (bb) states mixed by hyperfine interaction is used for determination of rovibronic level energies of the weakly bound I 2 (1 u (bb)) state. Dunham coefficients of the state, Y i0 (i = 0–3), Y i1 (i = 0–2), Y 02 and Y 12 for the v 1 u = 1–5, 8, 10, 15 and J 1 u ≈ 9–87 ranges, the dissociation energy of the state, D e , and equilibrium I–I distance, R e , as well as the potential energy curve are determined. There are aperiodicities in the excitation spectrum corresponding to the β, ν β = 23, J β ← 1 u (bb), ν 1u = 4, 5, J 1u progressions in the I 2 + Rg = He, Ar mixture, namely, a great number of lines which do not coincide with the R or P line progressions. Their positions conflict with the ΔJ-even selection rule. Furthermore, they do not correspond to the ΔJ-odd progression. (paper)
International Nuclear Information System (INIS)
Dote, Akinobu; Akaishi, Yoshinori; Yamazaki, Toshimitsu
2005-01-01
New nuclei 'K-bar-Mesic Nuclei' having the strangeness are described. At first it is shown that the strongly attractive nature of K-bar N interaction is reasoned inductively from consideration of the relation between Kaonic hydrogen atom and Λ (1405) which is an excited state of hyperon Λ. The K-bar N interactions are reviewed and summarized into three categories: 1. Phenomenological approach with density dependent K-bar N interaction (DD), relativistic mean field (RMF) approach, and hybrid of them (RMF+DD). 2. Boson exchange model. 3. Chiral SU(3) theory. The investigation of some light K-bar-nuclei by Akaishi and Yamazaki using phenomenological K-bar N interaction is explained in detail. Studies by antisymmetrized molecular dynamics (AMD) approach are also presented. From these theoretical researches, the following feature of K-bar-mesic nuclei are revealed: 1) Ground state is discrete and bound by 100 MeV or more. 2) Density is very high in side the K-bar-mesic nuclei. 3) Strange structures develop which are not seen in ordinary nuclei. Finally some recent experiments to explore K-bar-mesic nuclei are reviewed. (S. Funahashi)
International Nuclear Information System (INIS)
Janssens, R.V.F.; Khoo, T.L.
1991-01-01
Superdeformation was first proposed some twenty years ago to explain the fission isomers observed in some actinide nuclei. It was later realized that superdeformed shapes can occur at high angular momentum in lighter nuclei. The interest in the mechanisms responsible for these exotic shapes has increased enormously with the discovery of a superdeformed band of nineteen discrete lines in 152 Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132 Ce(9). Striking properties emerged from the first experiments, such as the essentially constant energy spacing between transitions (picket-fence spectra), the unexpectedly strong population of superdeformed bands at high spins, and the apparent lack of a link between the superdeformed states and the yrast levels. These findings were reviewed by Nolan and Twin. The present article follows upon their work and discusses the wealth of information that has since become available. This includes the discovery of a new island of superdeformation near A = 190, the detailed spectroscopy of ground and excited bands in the superdeformed well near A = 150 and A = 190, the surprising occurrence of superdeformed bands with identical transition energies in nuclei differing by one or two mass units, and the improved understanding of mechanisms responsible for the feeding into and the decay out of the superdeformed states
Effective field theory description of halo nuclei
Hammer, H.-W.; Ji, C.; Phillips, D. R.
2017-10-01
Nuclear halos emerge as new degrees of freedom near the neutron and proton driplines. They consist of a core and one or a few nucleons which spend most of their time in the classically-forbidden region outside the range of the interaction. Individual nucleons inside the core are thus unresolved in the halo configuration, and the low-energy effective interactions are short-range forces between the core and the valence nucleons. Similar phenomena occur in clusters of 4He atoms, cold atomic gases near a Feshbach resonance, and some exotic hadrons. In these weakly-bound quantum systems universal scaling laws for s-wave binding emerge that are independent of the details of the interaction. Effective field theory (EFT) exposes these correlations and permits the calculation of non-universal corrections to them due to short-distance effects, as well as the extension of these ideas to systems involving the Coulomb interaction and/or binding in higher angular-momentum channels. Halo nuclei exhibit all these features. Halo EFT, the EFT for halo nuclei, has been used to compute the properties of single-neutron, two-neutron, and single-proton halos of s-wave and p-wave type. This review summarizes these results for halo binding energies, radii, Coulomb dissociation, and radiative capture, as well as the connection of these properties to scattering parameters, thereby elucidating the universal correlations between all these observables. We also discuss how Halo EFT's encoding of the long-distance physics of halo nuclei can be used to check and extend ab initio calculations that include detailed modeling of their short-distance dynamics.
International Nuclear Information System (INIS)
Balian, Roger; Remaud, Bernard; Suraud, E.; Durand, Dominique; Tamain, Bernard; Gobbi, A.; Cugnon, J.; Drapier, Olivier; Govaerts, Jan; Prieels, Rene
1995-09-01
This 14. international school Joliot-Curie of nuclear physic deals with nuclei in collision at high energy. Nine lectures are included in the proceedings of this summer school: 1 - From statistical mechanics outside equilibrium to transport equations (Balian, R.); 2 - Modeling of heavy ions reactions (Remaud, B.); 3 - Kinetic equations in heavy ions physics (Suraud, E.); 4 - Colliding nuclei near the Fermi energy (Durand, D.; Tamain, B.); 5 - From the Fermi to the relativistic energy domain: which observable? For which physics? (Gobbi, A.); 6 - Collisions at relativistic and ultra relativistic energies, Theoretical aspects (Cugnon, J.); 7 - Quark-gluon plasma: experimental signatures (Drapier, O.); 8 - Electroweak interaction: a window on physics beyond the standard model (Govaerts, J.); 9 - Symmetry tests in β nuclear process: polarization techniques (Prieels, R.)
Nuclei, hadrons, and elementary particles
International Nuclear Information System (INIS)
Bopp, F.W.
1989-01-01
This book is a short introduction to the physics of the nuclei, hadrons, and elementary particles for students of physics. Important facts and model imaginations on the structure, the decay, and the scattering of nuclei, the 'zoology' of the hadrons and basic facts of hadronic scattering processes, a short introduction to quantum electrodynamics and quantum chromodynamics and the most important processes of lepton and parton physics, as well as the current-current approach of weak interactions and the Glashow-Weinberg-Salam theory are presented. (orig.) With 153 figs., 10 tabs [de
International Nuclear Information System (INIS)
Sugarbaker, E.
1995-01-01
I review available techniques for extraction of weak interaction rates in nuclei. The case for using hadron charge exchange reactions to estimate such rates is presented and contrasted with alternate methods. Limitations of the (p,n) reaction as a probe of Gamow-Teller strength are considered. Review of recent comparisons between beta-decay studies and (p,n) is made, leading to cautious optimism regarding the final usefulness of (p,n)- derived GT strengths to the field of astrophysics. copyright 1995 American Institute of Physics
International Nuclear Information System (INIS)
Leite Lopes, J.
1976-01-01
A survey of the fundamental ideas on weak currents such as CVC and PCAC and a presentation of the Cabibbo current and the neutral weak currents according to the Salam-Weinberg model and the Glashow-Iliopoulos-Miami model are given [fr
International Nuclear Information System (INIS)
Wojcicki, S.
1978-11-01
Lectures are given on weak decays from a phenomenological point of view, emphasizing new results and ideas and the relation of recent results to the new standard theoretical model. The general framework within which the weak decay is viewed and relevant fundamental questions, weak decays of noncharmed hadrons, decays of muons and the tau, and the decays of charmed particles are covered. Limitation is made to the discussion of those topics that either have received recent experimental attention or are relevant to the new physics. (JFP) 178 references
International Nuclear Information System (INIS)
Ogava, S.; Savada, S.; Nakagava, M.
1983-01-01
The problem of the use of weak interaction laws to study models of elementary particles is discussed. The most typical examples of weak interaction is beta-decay of nucleons and muons. Beta-interaction is presented by quark currents in the form of universal interaction of the V-A type. Universality of weak interactions is well confirmed using as examples e- and μ-channels of pion decay. Hypothesis on partial preservation of axial current is applicable to the analysis of processes with pion participation. In the framework of the model with four flavours lepton decays of hadrons are considered. Weak interaction without lepton participation are also considered. Properties of neutral currents are described briefly
International Nuclear Information System (INIS)
Chanda, R.
1981-01-01
The theoretical and experimental evidences to form a basis for Lagrangian Quantum field theory for Weak Interactions are discussed. In this context, gauge invariance aspects of such interactions are showed. (L.C.) [pt
Structure of Light Neutron-rich Nuclei
International Nuclear Information System (INIS)
Dlouhy, Zdenek
2007-01-01
In this contribution we searched for irregularities in various separation energies in the frame of mass measurement of neutron-rich nuclei at GANIL. On this basis we can summarize that the new doubly magic nuclei are 8 He, 22 O and 24 O. They are characterized by extra stability and, except 24 O, they cannot accept and bind additional neutrons. However, if we add to these nuclei a proton we obtain 9 Li and 25 F which are the core for two-neutron halo nucleus 11 Li and enables that fluorine can bound even 6 more neutrons, respectively. In that aspect the doubly magic nuclei in the neutron-rich region can form the basis either for neutron halo or very neutron-rich nuclei. (Author)
Directory of Open Access Journals (Sweden)
J. Adam
2016-01-01
Full Text Available We present results of a search for two hypothetical strange dibaryon states, i.e. the H-dibaryon and the possible Λn‾ bound state. The search is performed with the ALICE detector in central (0–10% Pb–Pb collisions at sNN=2.76 TeV, by invariant mass analysis in the decay modes Λn‾→d‾π+ and H-dibaryon →Λpπ−. No evidence for these bound states is observed. Upper limits are determined at 99% confidence level for a wide range of lifetimes and for the full range of branching ratios. The results are compared to thermal, coalescence and hybrid UrQMD model expectations, which describe correctly the production of other loosely bound states, like the deuteron and the hypertriton.
Adam, Jaroslav; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahmed, Ijaz; Ahn, Sang Un; Aimo, Ilaria; Aiola, Salvatore; Ajaz, Muhammad; Akindinov, Alexander; Alam, Sk Noor; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Armesto Perez, Nestor; Arnaldi, Roberta; Aronsson, Tomas; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baltasar Dos Santos Pedrosa, Fernando; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Bartke, Jerzy Gustaw; Bartsch, Esther; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batista Camejo, Arianna; Batyunya, Boris; Batzing, Paul Christoph; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Belmont Iii, Ronald John; Belmont Moreno, Ernesto; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhat, Inayat Rasool; Bhati, Ashok Kumar; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biswas, Saikat; Bjelogrlic, Sandro; Blanco, Fernando; Blau, Dmitry; Blume, Christoph; Bock, Friederike; Bogdanov, Alexey; Boggild, Hans; Boldizsar, Laszlo; Bombara, Marek; Book, Julian Heinz; Borel, Herve; Borissov, Alexander; Borri, Marcello; Bossu, Francesco; Botje, Michiel; Botta, Elena; Boettger, Stefan; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Broker, Theo Alexander; Browning, Tyler Allen; Broz, Michal; Brucken, Erik Jens; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Buxton, Jesse Thomas; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calero Diaz, Liliet; Caliva, Alberto; Calvo Villar, Ernesto; Camerini, Paolo; Carena, Francesco; Carena, Wisla; Castillo Castellanos, Javier Ernesto; Castro, Andrew John; Casula, Ester Anna Rita; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Chartier, Marielle; Charvet, Jean-Luc Fernand; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chelnokov, Volodymyr; Cherney, Michael Gerard; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Chochula, Peter; Choi, Kyungeon; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Connors, Megan Elizabeth; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Crochet, Philippe; Cruz Albino, Rigoberto; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dahms, Torsten; Dainese, Andrea; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; De Caro, Annalisa; De Cataldo, Giacinto; De Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; Deisting, Alexander; Deloff, Andrzej; Denes, Ervin Sandor; D'Erasmo, Ginevra; Di Bari, Domenico; Di Mauro, Antonio; Di Nezza, Pasquale; Diaz Corchero, Miguel Angel; Dietel, Thomas; Dillenseger, Pascal; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Domenicis Gimenez, Diogenes; Donigus, Benjamin; Dordic, Olja; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dupieux, Pascal; Ehlers Iii, Raymond James; Elia, Domenico; Engel, Heiko; Erazmus, Barbara Ewa; Erhardt, Filip; Eschweiler, Dominic; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Evdokimov, Sergey; Eyyubova, Gyulnara; Fabbietti, Laura; Fabris, Daniela; Faivre, Julien; Fantoni, Alessandra; Fasel, Markus; Feldkamp, Linus; Felea, Daniel; Feliciello, Alessandro; Feofilov, Grigorii; Ferencei, Jozef; Fernandez Tellez, Arturo; Gonzalez Ferreiro, Elena; Ferretti, Alessandro; Festanti, Andrea; Figiel, Jan; Araujo Silva Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Fleck, Martin Gabriel; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Furs, Artur; Fusco Girard, Mario; Gaardhoeje, Jens Joergen; Gagliardi, Martino; Gago Medina, Alberto Martin; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Gao, Chaosong; Garabatos Cuadrado, Jose; Garcia-Solis, Edmundo Javier; Gargiulo, Corrado; Gasik, Piotr Jan; Germain, Marie; Gheata, Andrei George; Gheata, Mihaela; Ghosh, Premomoy; Ghosh, Sanjay Kumar; Gianotti, Paola; Giubellino, Paolo; Giubilato, Piero; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez Ramirez, Andres; Gonzalez Zamora, Pedro; Gorbunov, Sergey; Gorlich, Lidia Maria; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grynyov, Borys; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerzoni, Barbara; Gulbrandsen, Kristjan Herlache; Gulkanyan, Hrant; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Haake, Rudiger; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harris, John William; Hartmann, Helvi; Harton, Austin Vincent; Hatzifotiadou, Despina; Hayashi, Shinichi; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hilden, Timo Eero; Hillemanns, Hartmut; Hippolyte, Boris; Hristov, Peter Zahariev; Huang, Meidana; Humanic, Thomas; Hussain, Nur; Hussain, Tahir; Hutter, Dirk; Hwang, Dae Sung; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Ionita, Costin; Ippolitov, Mikhail; Irfan, Muhammad; Ivanov, Marian; Ivanov, Vladimir; Izucheev, Vladimir; Jacholkowski, Adam Wlodzimierz; Jacobs, Peter Martin; Jahnke, Cristiane; Jang, Haeng Jin; Janik, Malgorzata Anna; Pahula Hewage, Sandun; Jena, Chitrasen; Jena, Satyajit; Jimenez Bustamante, Raul Tonatiuh; Jones, Peter Graham; Jung, Hyungtaik; Jusko, Anton; Kalinak, Peter; Kalweit, Alexander Philipp; Kamin, Jason Adrian; Kang, Ju Hwan; Kaplin, Vladimir; Kar, Somnath; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kebschull, Udo Wolfgang; Keidel, Ralf; Keijdener, Darius Laurens; Keil, Markus; Khan, Kamal; Khan, Mohammed Mohisin; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Do Won; Kim, Dong Jo; Kim, Hyeonjoong; Kim, Jinsook; Kim, Mimae; Kim, Minwoo; Kim, Se Yong; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Kiss, Gabor; Klay, Jennifer Lynn; Klein, Carsten; Klein, Jochen; Klein-Boesing, Christian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Kobayashi, Taiyo; Kobdaj, Chinorat; Kofarago, Monika; Kohler, Markus Konrad; Kollegger, Thorsten; Kolozhvari, Anatoly; Kondratev, Valerii; Kondratyeva, Natalia; Kondratyuk, Evgeny; Konevskikh, Artem; Kouzinopoulos, Charalampos; Kovalenko, Vladimir; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kravcakova, Adela; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Kryshen, Evgeny; Krzewicki, Mikolaj; Kubera, Andrew Michael; Kucera, Vit; Kucheryaev, Yury; Kugathasan, Thanushan; Kuhn, Christian Claude; Kuijer, Paulus Gerardus; Kulakov, Igor; Kumar, Jitendra; Lokesh, Kumar; Kurashvili, Podist; Kurepin, Alexander; Kurepin, Alexey; Kuryakin, Alexey; Kushpil, Svetlana; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Lagana Fernandes, Caio; Lakomov, Igor; Langoy, Rune; Lara Martinez, Camilo Ernesto; Lardeux, Antoine Xavier; Lattuca, Alessandra; Laudi, Elisa; Lea, Ramona; Leardini, Lucia; Lee, Graham Richard; Lee, Seongjoo; Legrand, Iosif; Lehnert, Joerg Walter; Lemmon, Roy Crawford; Lenti, Vito; Leogrande, Emilia; Leon Monzon, Ildefonso; Leoncino, Marco; Levai, Peter; Li, Shuang; Li, Xiaomei; Lien, Jorgen Andre; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Ljunggren, Hans Martin; Lodato, Davide Francesco; Lonne, Per-Ivar; Loggins, Vera Renee; Loginov, Vitaly; Loizides, Constantinos; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lowe, Andrew John; Lu, Xianguo; Luettig, Philipp Johannes; Lunardon, Marcello; Luparello, Grazia; Maevskaya, Alla; Mager, Magnus; Mahajan, Sanjay; Mahmood, Sohail Musa; Maire, Antonin; Majka, Richard Daniel; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Liudmila; Mal'Kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Margutti, Jacopo; Marin, Ana Maria; Markert, Christina; Marquard, Marco; Martashvili, Irakli; Martin, Nicole Alice; Martin Blanco, Javier; Martinengo, Paolo; Martinez Hernandez, Mario Ivan; Martinez-Garcia, Gines; Martinez Pedreira, Miguel; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Massacrier, Laure Marie; Mastroserio, Annalisa; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel Anthony; Mazzoni, Alessandra Maria; Mcdonald, Daniel; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Meninno, Elisa; Mercado-Perez, Jorge; Meres, Michal; Miake, Yasuo; Mieskolainen, Matti Mikael; Mikhaylov, Konstantin; Milano, Leonardo; Milosevic, Jovan; Minervini, Lazzaro Manlio; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz Czeslaw; Mitra, Jubin; Mitu, Ciprian Mihai; Mohammadi, Naghmeh; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Montes Prado, Esther; Morando, Maurizio; Moretto, Sandra; Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhlheim, Daniel Michael; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Mulligan, James Declan; Gameiro Munhoz, Marcelo; Murray, Sean; Musa, Luciano; Musinsky, Jan; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Naru, Muhammad Umair; Nattrass, Christine; Nayak, Kishora; Nayak, Tapan Kumar; Nazarenko, Sergey; Nedosekin, Alexander; Nellen, Lukas; Ng, Fabian; Nicassio, Maria; Niculescu, Mihai; Niedziela, Jeremi; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Norman, Jaime; Nyanin, Alexander; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Ohlson, Alice Elisabeth; Okatan, Ali; Okubo, Tsubasa; Olah, Laszlo; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Oliver, Michael Henry; Onderwaater, Jacobus; Oppedisano, Chiara; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Ozdemir, Mahmut; Pachmayer, Yvonne Chiara; Pagano, Paola; Paic, Guy; Pajares Vales, Carlos; Pal, Susanta Kumar; Pan, Jinjin; Pandey, Ashutosh Kumar; Pant, Divyash; Papikyan, Vardanush; Pappalardo, Giuseppe; Pareek, Pooja; Park, Woojin; Parmar, Sonia; Passfeld, Annika; Paticchio, Vincenzo; Paul, Biswarup; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitry Yurevich; Perez Lara, Carlos Eugenio; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petrov, Viacheslav; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Porteboeuf, Sarah Julie; Porter, R Jefferson; Pospisil, Jan; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Punin, Valery; Putschke, Jorn Henning; Qvigstad, Henrik; Rachevski, Alexandre; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Razazi, Vahedeh; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reed, Rosi Jan; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reicher, Martijn; Reidt, Felix; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riabov, Viktor; Ricci, Renato Angelo; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-Lucian; Rivetti, Angelo; Rocco, Elena; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roeed, Ketil; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Romita, Rosa; Ronchetti, Federico; Ronflette, Lucile; Rosnet, Philippe; Rossi, Andrea; Roukoutakis, Filimon; Roy, Ankhi; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Sadovskiy, Sergey; Safarik, Karel; Sahlmuller, Baldo; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Saleh, Mohammad Ahmad; Salgado Lopez, Carlos Alberto; Salzwedel, Jai Samuel Nielsen; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Santagati, Gianluca; Sarkar, Debojit; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schuchmann, Simone; Schukraft, Jurgen; Schulc, Martin; Schuster, Tim Robin; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Rebecca Michelle; Seeder, Karin Soraya; Seger, Janet Elizabeth; Sekiguchi, Yuko; Selyuzhenkov, Ilya; Senosi, Kgotlaesele; Seo, Jeewon; Serradilla Rodriguez, Eulogio; Sevcenco, Adrian; Shabanov, Arseniy; Shabetai, Alexandre; Shadura, Oksana; Shahoyan, Ruben; Shangaraev, Artem; Sharma, Ankita; Sharma, Natasha; Shigaki, Kenta; Shtejer Diaz, Katherin; Sibiryak, Yury; Siddhanta, Sabyasachi; Sielewicz, Krzysztof Marek; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine Micaela; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Slupecki, Maciej; Smirnov, Nikolai; Snellings, Raimond; Snellman, Tomas Wilhelm; Soegaard, Carsten; Soltz, Ron Ariel; Song, Jihye; Song, Myunggeun; Song, Zixuan; Soramel, Francesca; Sorensen, Soren Pontoppidan; Spacek, Michal; Spiriti, Eleuterio; Sputowska, Iwona Anna; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Steinpreis, Matthew Donald; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Sultanov, Rishat; Sumbera, Michal; Symons, Timothy; Szabo, Alexander; Szanto De Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szymanski, Maciej Pawel; Takahashi, Jun; Tanaka, Naoto; Tangaro, Marco-Antonio; Tapia Takaki, Daniel Jesus; Tarantola Peloni, Attilio; Tariq, Mohammad; Tarzila, Madalina-Gabriela; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terasaki, Kohei; Terrevoli, Cristina; Teyssier, Boris; Thaeder, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony Robert; Toia, Alberica; Trogolo, Stefano; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; Van Der Maarel, Jasper; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vanat, Tomas; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vechernin, Vladimir; Veen, Annelies Marianne; Veldhoen, Misha; Velure, Arild; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara Limon, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Vislavicius, Vytautas; Viyogi, Yogendra; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Vranic, Danilo; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Jan; Wang, Hongkai; Wang, Mengliang; Wang, Yifei; Watanabe, Daisuke; Weber, Michael; Weber, Steffen Georg; Wessels, Johannes Peter; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Williams, Crispin; Windelband, Bernd Stefan; Winn, Michael Andreas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Ping; Yano, Satoshi; Yasnopolskiy, Stanislav; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-Kwon; Yurchenko, Volodymyr; Yushmanov, Igor; Zaborowska, Anna; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correia Zanoli, Henrique Jose; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhang, Yonghong; Zhao, Chengxin; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zyzak, Maksym
2016-01-10
We present results of a search for two hypothetical strange dibaryon states, i.e. the H-dibaryon and the possible $\\overline{\\Lambda\\mathrm{n}}$ bound state. The search is performed with the ALICE detector in central (0-10%) Pb-Pb collisions at $ \\sqrt{s_{\\rm{NN}}} = 2.76$ TeV, by invariant mass analysis in the decay modes $\\overline{\\Lambda\\mathrm{n}} \\rightarrow \\overline{\\mathrm{d}} \\pi^{+} $ and H-dibaryon $\\rightarrow \\Lambda \\mathrm{p} \\pi^{-}$. No evidence for these bound states is observed. Upper limits are determined at 99% confidence level for a wide range of lifetimes and for the full range of branching ratios. The results are compared to thermal, coalescence and hybrid UrQMD model expectations, which describe correctly the production of other loosely bound states, like the deuteron and the hypertriton.
Spin effects in the weak interaction
International Nuclear Information System (INIS)
Freedman, S.J.; Chicago Univ., IL; Chicago Univ., IL
1990-01-01
Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon
Chaos in nuclei: Theory and experiment
Muñoz, L.; Molina, R. A.; Gómez, J. M. G.
2018-05-01
During the last three decades the quest for chaos in nuclei has been quite intensive, both with theoretical calculations using nuclear models and with detailed analyses of experimental data. In this paper we outline the concept and characteristics of quantum chaos in two different approaches, the random matrix theory fluctuations and the time series fluctuations. Then we discuss the theoretical and experimental evidence of chaos in nuclei. Theoretical calculations, especially shell-model calculations, have shown a strongly chaotic behavior of bound states in regions of high level density. The analysis of experimental data has shown a strongly chaotic behavior of nuclear resonances just above the one-nucleon emission threshold. For bound states, combining experimental data of a large number of nuclei, a tendency towards chaotic motion is observed in spherical nuclei, while deformed nuclei exhibit a more regular behavior associated to the collective motion. On the other hand, it had never been possible to observe chaos in the experimental bound energy levels of any single nucleus. However, the complete experimental spectrum of the first 151 states up to excitation energies of 6.20 MeV in the 208Pb nucleus have been recently identified and the analysis of its spectral fluctuations clearly shows the existence of chaotic motion.
International Nuclear Information System (INIS)
Robertson, R.G.H.
1980-01-01
A summary of parity violating effects in nuclei is given. Thanks to vigorous experimental and theoretical effort, it now appears that a reasonably well-defined value for the weak isovector π-nucleon coupling constant can be obtained. There is one major uncertainty in the analysis, namely the M2/E1 mixing ratio for the 2.79 MeV transition in 21 Ne. This quantity is virtually impossible to calculate reliably and must be measured. If it turns out to be much larger than 1, then a null result in 21 Ne is expected no matter what the weak interaction, so an experimental determination is urgently needed. The most promising approach is perhaps a measurement of the pair internal conversion coefficient. Of course, a direct measurement of a pure isovector case is highly desirable, and it is to be hoped that the four ΔT = 1 experiments will be pushed still further, and that improved calculations will be made for the 6 Li case. Nuclear parity violation seems to be rapidly approaching an interesting and useful synthesis
Deeply bound pionic states and modifications of hadrons
International Nuclear Information System (INIS)
Hirenzaki, S.
2000-01-01
We have studied the structure and formation of mesic atoms and mesic nuclei theoretically. The latest results on the deeply bound pionic atoms, the kaonic atoms and the sigma states are reported. (author)
Selleri, Franco
2015-01-01
Weak Relativity is an equivalent theory to Special Relativity according to Reichenbach’s definition, where the parameter epsilon equals to 0. It formulates a Neo-Lorentzian approach by replacing the Lorentz transformations with a new set named “Inertial Transformations”, thus explaining the Sagnac effect, the twin paradox and the trip from the future to the past in an easy and elegant way. The cosmic microwave background is suggested as a possible privileged reference system. Most importantly, being a theory based on experimental proofs, rather than mutual consensus, it offers a physical description of reality independent of the human observation.
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1998-01-01
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors)
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)
1998-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors) 304 refs., 53 figs., 5 tabs.
Strength of Coriolis Coupling in actinide nuclei
International Nuclear Information System (INIS)
Peker, L.K.; Rasmussen, J.O.; Hamilton, J.H.
1982-01-01
Coriolis Coupling V/sub cor/ plays an important role in deformed nuclei. V/sub cor/ is proportional to h 2 /J[j (j + 1) -Ω (Ω + 1)]/sup 1/2/ and therefore is particularly significant in the nuclei with large j and low Ω Nilsson levels close to Fermi surface: n(i/sub 13/2/) in A = 150 to 170 rare-earth nuclei and p(i/sub 13/2/) and n(j/sub 15/2/) in A greater than or equal to 224 actinide nuclei. Because of larger j (n(j/sub 15/2/) versus n(i/sub 13/2/)) and smaller deformations (β approx. = 0.22 versus β 0.28) it was reasonable to expect that in actinide nuclei Coriolis effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed Coriolis effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis ad pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction V/sub eff/ of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda F). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction V/sub eff/ is strong, and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei
MAGIC NUCLEI: Tin-100 turns up
International Nuclear Information System (INIS)
Anon.
1994-01-01
In the same way as the Periodic Table of chemical elements reflects the successive filling of orbital electron shells, in nuclear physics the socalled 'magic' numbers correspond to closed shells of 2, 8, 20, 28, 50, 82, 126,... neutrons and/or protons. More tightly bound than other nuclei, these are the nuclear analogues of the inert gases. 'Doubly magic' nuclei have closed shells of both neutrons and protons. Examples in nature are helium-4 (2 protons and 2 neutrons), oxygen-16 (8 and 8), calcium-40 (20 and 20) and calcium-48 (20 and 28). Radioactive tin-132 (50+82) has been widely studied
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1997-01-01
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author)
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph
1997-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author) 270 refs.
Structure of neutron-rich nuclei
International Nuclear Information System (INIS)
Nazarewicz, W.
2000-01-01
Complete text of publication follows. The uncharted regions of the (N,Z) plane contain information that can answer many questions of fundamental importance for science: How many protons and neutrons can be clustered together by the strong interaction to form a bound nucleus? What are the proton and neutron magic numbers of the exotic nuclei? What are the properties of very short-lived exotic nuclei with extreme neutron-to-proton ratios? What is the effective nucleon-nucleon interaction in a nucleus that has a very large neutron excess? Nuclear life far from stability is different from that around the stability line; the promised access to completely new combinations of proton and neutron numbers offers prospects for new structural phenomena. The main objective of this talk is to discuss some of the challenges and opportunities of research with exotic nuclei. The covered topics will include: Theoretical challenges; Skins and halos in heavy nuclei; Shape coexistence in exotic nuclei; Beta-decays of neutron-rich nuclei. (author)
Exotic Nuclei and Yukawa's Forces
International Nuclear Information System (INIS)
Otsuka, Takaharu; Suzuki, Toshio; Utsuno, Yutaka
2008-01-01
In this plenary talk, we will overview the evolution of the shell structure in stable and exotic nuclei as a new paradigm of nuclear structure physics. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The nuclear magic numbers have been believed, since Mayer and Jensen, to be constants as 2, 8, 20, 28, 50, ... This turned out to be changed, once we entered the regime of exotic nuclei. This shell evolution develops at many places on the nuclear chart in various forms. For example, superheavy magic numbers may be altered. Thus, we are led to a new paradigm as to how and where the nuclear shell evolves, and what consequences arise. The evolution of the shell affects weak process transitions, and plays a crucial role in deformation. The π and ρ mesons generate tensor forces, and are the fundamental elements of such intriguing phenomena. Thus, physics of exotic nuclei arises as a manifestation of Yukawa's forces
International Nuclear Information System (INIS)
Angelique, J.C.; Orr, N.A.
1997-01-01
The study of the nuclei far off stability valley is of much interest for testing the nuclear models established for the stable nuclei but also for astrophysics to understand the nucleosynthesis. Experiments aim to measure the mass and lifetime, to build the decay schemes and also to study the structure and the properties of these nuclei. The radioactive beam group focused its research on light neutron-rich nuclei having a halo neutron structure. Mass measurements in N ∼ Z nuclei namely in A ∼ 60-80 proton-rich nuclei, important for understanding the rp process, are mentioned, as well as in nuclei in the 100 Sn region. In the newly obtained 26 O and 28 O nuclei the lifetimes, the probabilities of emission of one for more neutrons were determined. The data analysis has permitted to determine also for the first time the lifetimes of 27,29 F and 30 Ne. Studies of nuclei in the 100 Sn region, near the proton drip line in the ground and isomeric states are now under way. The spectroscopy (energy levels, gamma emissions, etc.) of the neutron-rich nuclei produced by the 36 S fragmentation has been carried out in 31 Ne, 17 B and 29 F. Studies by Coulomb excitation of the 2 + excited states and associated probability B (E2) in O, Ne, Ni and Zn are now analysed
Axial asymmetry of excited heavy nuclei as essential feature for the prediction of level densities
Energy Technology Data Exchange (ETDEWEB)
Grosse, Eckart [Institute of Nuclear and Particle Physics, Technische Universitaet Dresden (Germany); Junghans, Arnd R. [Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf (Germany); Massarczyk, Ralph [Los Alamos National Laboratory, New Mexico (United States)
2016-07-01
In previous studies a considerable improvement of predictions for neutron resonance spacings by a modified back-shifted Fermi-gas model (BSFM) was found. The modifications closely follow the basic principles for a gas of weakly bound Fermions as given in text books of statistical physics: (1) Phase transition at a temperature defined by theory, (2) pairing condensation independent of A, and (3) proportionality of entropy to temperature (and thus the level density parameter) fixed by the Fermi energy. For finite nuclei we add: (4) the back-shift energy is defined by shell correction and (5) the collective enhancement is enlarged by allowing the axial symmetry to be broken. Nearly no parameter fitting is needed to arrive at a good reproduction of level density information obtained by various methods for a number of nuclei in a wide range of A and E. To that end the modified BSFM is complemented by a constant temperature approximation below the phase transition point. The axial symmetry breaking (5), which is an evidently essential feature, will also be regarded with respect to other observables for heavy nuclei.
International Nuclear Information System (INIS)
Chomaz, Ph.
2000-01-01
This document gathers the slides and their commentaries that have been presented at the conference 'physics and fundamental questions' by P. Chomaz. The author reviews the different quantum aspects of nuclei: tunnel effect, symmetries, magic numbers, wave functions, size, shapes and deformations. The author shows that nuclei are quantum objects of great complexity, their structures are not yet well understood and the study of exotic nuclei will continue bringing valuable information
Pairing correlations in nuclei
International Nuclear Information System (INIS)
Baba, C.V.K.
1988-01-01
There are many similarities between the properties of nucleons in nuclei and electrons in metals. In addition to the properties explainable in terms of independent particle motion, there are many important co-operative effects suggesting correlated motion. Pairing correlation which leads to superconductivity in metals and several important properties in nuclei , is an exmple of such correlations. An attempt has been made to review the effects of pairing correlations in nuclei. Recent indications of reduction in pairing correlations at high angular momenta is discussed. A comparision between pairing correlations in the cases of nuclei and electrons in metals is attempted. (author). 20 refs., 10 figs
Nuclei with exotic constituents
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1990-08-01
We discuss various interesting features in the behavior of exotic constituents of nuclei such as hyperons and mesons, in particular, with emphases on the aspect of exotic halos which are formed in general by short-range repulsion and long-range attraction. Specifically, Λ and Σ hypernuclei and pionic nuclei are discussed. (author)
International Nuclear Information System (INIS)
Foucher, R.
1979-01-01
If some β - emitters are particularly interesting to study in light, medium, and heavy nuclei, another (and also) difficult problem is to know systematically the properties of these neutron rich nuclei far from the stability line. A review of some of their characteristics is presented. How far is it possible to be objective in the interpretation of data is questioned and implications are discussed
International Nuclear Information System (INIS)
Arenhoevel, H.
1977-01-01
The field of baryon resonances in nuclei is reviewed. Theoretical developments and experimental evidence as well are discussed. Special emphasis is laid on electromagnetic processes for the two nucleon system. Some aspects of real isobars in nuclei are touched upon. (orig.) [de
International Nuclear Information System (INIS)
Szymanski, Z.; Berger, J.F.; Heenen, P.H.; Heyde, K.; Haas, B.; Janssens, R.; Paya, D.; Gogny, D.; Huber, G.; Bjoernholm, S.; Brack, M.
1991-01-01
The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters
International Nuclear Information System (INIS)
Liu, L.C.
1987-01-01
The possibility of producing eta-mesic nuclei by the use of pions is discussed. If these nuclei are observed experimentally, then the binding energies of the eta in this new nuclear matter can be used to extract accurately the eta-N-N* coupling constant in a nucleus. The framework for these calculations is the coupled channel isobar model
Conflicting coupling of unpaired nucleons in odd-odd nuclei
International Nuclear Information System (INIS)
Volkov, D.A.; Levon, A.I.
1990-01-01
Phenomenological approach is described, using it, energy spectra of odd-odd nucleus collective bands based on conflicting state of unpaired nucleons can be calculated. It is ascertained that in a conflicting bond unpaired nucleon acts as a spectator, i.e. energy spectra of collective bands in odd-odd nuclei are similar to the spectra of collective bands in heighbouring odd nuclei, which are based on the state of a strongly bound nucleon is included in the conflicting configuration
Hue, B. M.; Isataev, T.; Erdemchimeg, B.; Artukh, A. G.; Aznabaev, D.; Davaa, S.; Klygin, S. A.; Kononenko, G. A.; Khuukhenkhuu, G.; Kuterbekov, K.; Lukyanov, S. M.; Mikhailova, T. I.; Maslov, V. A.; Mendibaev, K.; Sereda, Yu M.; Penionzhkevich, Yu E.; Vorontsov, A. N.
2017-12-01
Preliminary results of measurements of the total reaction cross sections σR and neutron removal cross section σ-xn for weakly bound 6He, 8Li, 9Be and 10Be nuclei at energy range (20-35) A MeV with 28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 22Ne (35 A MeV) primary beam on Be target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (20-35) A MeV. Two-neutron removal cross sections for 6He and 10Be and one -neutron removal cross sections 8Li and 9Be were measured.
Reconstructing weak values without weak measurements
International Nuclear Information System (INIS)
Johansen, Lars M.
2007-01-01
I propose a scheme for reconstructing the weak value of an observable without the need for weak measurements. The post-selection in weak measurements is replaced by an initial projector measurement. The observable can be measured using any form of interaction, including projective measurements. The reconstruction is effected by measuring the change in the expectation value of the observable due to the projector measurement. The weak value may take nonclassical values if the projector measurement disturbs the expectation value of the observable
Multipole giant resonances in highly excited nuclei
International Nuclear Information System (INIS)
Xia Keding; Cai Yanhuang
1989-01-01
The isoscalar giant surface resonance and giant dipole resonance in highly excited nuclei are discussed. Excitation energies of the giant modes in 208 Pb are calculated in a simplified model, using the concept of energy wieghted sum rule (EWSR), and the extended Thomas-Fermi approximation at the finite temperature is employed to describe the finite temperature is employed to describe the finite temperature equilibrium state. It is shown that EWSR and the energy of the resonance depend only weakly on temperature in the system. This weak dependence is analysed
Fusion and direct reactions for strongly and weakly bound projectiles
International Nuclear Information System (INIS)
Hugi, M.; Lang, J.; Mueller, R.; Ungricht, E.; Bodek, K.; Jarczyk, L.; Kamys, B.; Magiera, A.; Strzalkowski, A.; Willim, G.
1981-01-01
The interaction of 6 Li, 9 Be and 12 C projectiles with a 28 Si target was investigated by measuring the angular distributions of the elasitcally scattered projectiles and of the emitted protons, deuterons and α-particles. The experiment was perfomred in order to deduce direct and compound nucleus process contributions to the total reaction cross section and to study the influence of the projectile structure on the relative importance of these two mechanisms. Optical model parameters and therefore the total reaction cross section are strongly influenced by the binding energy of the projectile. The parameters of the Glas-Mosel describing the fusion reaction vary smoothly with the atomic number. In the system 9 B + 28 Si around 50% of all reactions are direct processes even at energies near the Coulomb barrier, whereas in the other systeme the direct part amounts to 15% ( 12 C) and 30% ( 6 Li) only. (orig.)
Induction, bounding, weak combinatorial principles, and the homogeneous model theorem
Hirschfeldt, Denis R; Shore, Richard A
2017-01-01
Goncharov and Peretyat'kin independently gave necessary and sufficient conditions for when a set of types of a complete theory T is the type spectrum of some homogeneous model of T. Their result can be stated as a principle of second order arithmetic, which is called the Homogeneous Model Theorem (HMT), and analyzed from the points of view of computability theory and reverse mathematics. Previous computability theoretic results by Lange suggested a close connection between HMT and the Atomic Model Theorem (AMT), which states that every complete atomic theory has an atomic model. The authors show that HMT and AMT are indeed equivalent in the sense of reverse mathematics, as well as in a strong computability theoretic sense and do the same for an analogous result of Peretyat'kin giving necessary and sufficient conditions for when a set of types is the type spectrum of some model.
Pions in nuclei, from virtual-pion exchange to real-pion transfer
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1988-07-01
Tracing the work of Miyazawa on nuclear magnetic moments, we discuss possible experimental ways to see whether a real pion exists in nuclei or not. While virtual pions are known to play an important role in nuclei, as clarified experimentally from anomalous orbital g factors of nucleons in nuclei, nearly nothing is known for the behavior of real pions in nuclei. We have shown that deeply bound hybrid states of π - are expected to exist in heavy nuclei, which can be populated by ''pion transfer'' reactions. (author)
International Nuclear Information System (INIS)
Grange, P.; Mathiot, J.F.; Roy-Stephan, M.; Frascaria, R.; Gales, S.
1990-01-01
The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis [fr
Dynamic polarisation of nuclei
International Nuclear Information System (INIS)
Borghini, M.; Abragam, A.
1961-01-01
In magnetic fields of about 13000 gauss, at a temperature of 1.5 deg. K, in samples of about 2 mm 3 , we have obtained by the 'solid effect' (application of a magnetic field at an appropriate frequency around 35000 MHz), nuclear polarizations /I of a few percent: 19 per cent for hydrogen nuclei in single crystals of La 2 Mg 3 (NO 3 ) 12 , 24H 2 O; 5 per cent for hydrogen nuclei in polystyrene; 6 per cent for fluorine nuclei in single crystals of LiF. (author) [fr
On Weakly Singular Versions of Discrete Nonlinear Inequalities and Applications
Directory of Open Access Journals (Sweden)
Kelong Cheng
2014-01-01
Full Text Available Some new weakly singular versions of discrete nonlinear inequalities are established, which generalize some existing weakly singular inequalities and can be used in the analysis of nonlinear Volterra type difference equations with weakly singular kernels. A few applications to the upper bound and the uniqueness of solutions of nonlinear difference equations are also involved.
Selfconsistent calculations for hyperdeformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D. [Universite Louis Pasteur, Strasbourg (France)
1996-12-31
Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.
Mohri, Mehryar; Rostamizadeh, Afshin
2013-01-01
We present a brief survey of existing mistake bounds and introduce novel bounds for the Perceptron or the kernel Perceptron algorithm. Our novel bounds generalize beyond standard margin-loss type bounds, allow for any convex and Lipschitz loss function, and admit a very simple proof.
International Nuclear Information System (INIS)
Roberts, R.G.
1984-11-01
The paper concerns the behaviour of quarks in nuclei. Confinement size changes and dynamical rescaling; A dependence; low-x region; gluons and confinement size; and nucleons in a nucleus; are all discussed. (U.K.)
International Nuclear Information System (INIS)
Mackintosh, R.S.
1977-01-01
For the class of nuclei which are 'strongly deformed' it is possible to introduce the idea of an empirically measurable static nuclear shape. The limitations of this concept as applied to nuclei (fundamentally quantum-mechanical objects) are discussed. These are basically the limitations of the rotational model which must be introduced in order to define and measure nuclear shape. A unified discussion of the ways in which the shape has been parametrized is given with emphasis on the fact that different parametrizations correspond to different nuclear structures. Accounts of the various theoretical procedures for calculating nuclear shapes and of the interaction between nuclear shapes and nuclear spectroscopy are given. A coherent account of a large subset of nuclei (strongly deformed nuclei) can be given by means of a model in which the concept of nuclear shape plays a central role. (author)
International Nuclear Information System (INIS)
Aaberg, S.; Uhrenholt, H.
2009-01-01
We study the structure of nuclei in the energy region between the ground state and the neutron separation energy, here called warm nuclei. The onset of chaos in the nucleus as excitation energy is increased is briefly reviewed. Chaos implies fluctuations of energies and wave functions qualitatively the same for all chaotic nuclei. On the other hand, large structure effects are seen, e.g. in the level-density function at same excitation energies. A microscopic model for the level density is reviewed and we discuss effects on structure of the total level-density function, parity enhancement, and the spin distribution function. Comparisons to data are performed at the neutron separation energy for all observed nuclei, and structure of the level-density function for a few measured cases. The role of structure effects in the level-density function for fission dynamics is exemplified.
Meson-nucleus potentials and the search for meson-nucleus bound states
Metag, V.; Nanova, M.; Paryev, E. Ya.
2017-11-01
Recent experiments studying the meson-nucleus interaction to extract meson-nucleus potentials are reviewed. The real part of the potentials quantifies whether the interaction is attractive or repulsive while the imaginary part describes the meson absorption in nuclei. The review is focused on mesons which are sufficiently long-lived to potentially form meson-nucleus quasi-bound states. The presentation is confined to meson production off nuclei in photon-, pion-, proton-, and light-ion induced reactions and heavy-ion collisions at energies near the production threshold. Tools to extract the potential parameters are presented. In most cases, the real part of the potential is determined by comparing measured meson momentum distributions or excitation functions with collision model or transport model calculations. The imaginary part is extracted from transparency ratio measurements. Results on K+ ,K0 ,K- , η ,η‧ , ω, and ϕ mesons are presented and compared with theoretical predictions. The interaction of K+ and K0 mesons with nuclei is found to be weakly repulsive, while the K- , η ,η‧ , ω and ϕ meson-nucleus potentials are attractive, however, with widely different strengths. Because of meson absorption in the nuclear medium the imaginary parts of the meson-nucleus potentials are all negative, again with a large spread. An outlook on planned experiments in the charm sector is given. In view of the determined potential parameters, the criteria and chances for experimentally observing meson-nucleus quasi-bound states are discussed. The most promising candidates appear to be the η and η‧ mesons.
International Nuclear Information System (INIS)
Guerreau, D.
1993-01-01
A review is made of the present status concerning the production of nuclei above 5 MeV temperature. Considerable progress has been made recently on the understanding of the formation and the fate of such hot nuclei. It appears that the nucleus seems more stable against temperature than predicted by static calculations. However, the occurrence of multifragment production at high excitation energies is now well established. The various experimental features of the fragmentation process are discussed. (author) 59 refs., 12 figs
Weak limits for quantum random walks
International Nuclear Information System (INIS)
Grimmett, Geoffrey; Janson, Svante; Scudo, Petra F.
2004-01-01
We formulate and prove a general weak limit theorem for quantum random walks in one and more dimensions. With X n denoting position at time n, we show that X n /n converges weakly as n→∞ to a certain distribution which is absolutely continuous and of bounded support. The proof is rigorous and makes use of Fourier transform methods. This approach simplifies and extends certain preceding derivations valid in one dimension that make use of combinatorial and path integral methods
Weak mixing below the weak scale in dark-matter direct detection
Brod, Joachim; Grinstein, Benjamin; Stamou, Emmanuel; Zupan, Jure
2018-02-01
If dark matter couples predominantly to the axial-vector currents with heavy quarks, the leading contribution to dark-matter scattering on nuclei is either due to one-loop weak corrections or due to the heavy-quark axial charges of the nucleons. We calculate the effects of Higgs and weak gauge-boson exchanges for dark matter coupling to heavy-quark axial-vector currents in an effective theory below the weak scale. By explicit computation, we show that the leading-logarithmic QCD corrections are important, and thus resum them to all orders using the renormalization group.
Circuit lower bounds in bounded arithmetics
Czech Academy of Sciences Publication Activity Database
Pich, Ján
2015-01-01
Roč. 166, č. 1 (2015), s. 29-45 ISSN 0168-0072 R&D Projects: GA AV ČR IAA100190902 Keywords : bounded arithmetic * circuit lower bounds Subject RIV: BA - General Mathematics Impact factor: 0.582, year: 2015 http://www.sciencedirect.com/science/article/pii/S0168007214000888
Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis
Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu
Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.
Status and perspectives of the search for Eta-Mesic nuclei
Energy Technology Data Exchange (ETDEWEB)
Moskal, Paweł, E-mail: p.moskal@uj.edu.pl; Skurzok, Magdalena, E-mail: magdalena.skurzok@if.uj.edu.pl [M. Smoluchowski Institute of Physics, Jagiellonian University, 30-348 Cracow (Poland); Krzemień, Wojciech, E-mail: wojciech.krzemien@ncbj.gov.pl [National Centre for Nuclear Research, Świerk, 05-400 Otwock (Poland)
2016-07-07
In this report the search for η-mesic nuclei is reviewed. The brief description of the experimental studies is presented with a focus on the possible production of the η-nucleus bound states for light nuclei like {sup 4}He and {sup 3}He.
International Nuclear Information System (INIS)
Louchart, C.
2012-01-01
Spectroscopy of exotic nuclei has allowed numerous discoveries in nuclear structure: the shell structure changes and the magic numbers are not persistent when moving toward the drip lines. The study of exotic nuclei requires experimental spectroscopic data which give information on the deformation and the nature of excited states of the studied nucleus. Around 68 Ni, which presents signs of shell closure at N=40 (high excitation energy of the 2 + 1 and low B(E2; 2 + →0 + ) exotic nuclei, like Cr, Fe, Zn and Ge, present deformation and recent experiments point to a rapid development of collectivity. The experiment done at LNL (Laboratori Nazionali di Legnaro) on 70,72,74 Zn isotopes concluded a surprisingly long life time for the 4 + states of 74 Zn, leading to a ratio of B(E2; 4 + → 2 + ) to B(E2; 2 + → 0 + ) very low, not explained by calculations beyond mean field or shell models. This experiment was one of the first with the AGATA demonstrator. Two types of direct reactions are used to extract spectroscopic factors: knockout and low energy transfer reactions. The experimental values are not consistent between the two case s for the removal of one deeply bound nucleon in the nuclei. This difference could come from an incorrect modeling of the reaction mechanism of knockout reactions. Calculations based on intra-nuclear cascade followed by an evaporation phase show weaknesses in the sudden approximation. (author) [fr
Beta decay of polarized nuclei and the decay asymmetry of 8Li
International Nuclear Information System (INIS)
Bigelow, R.; Freedman, S.J.; Napolitano, J.; Quin, P.A.
1985-01-01
Under certain conditions, it is possible to produce vector-polarized radioactive nuclei in reactions with a polarized projectile and an unpolarized target. Using the intense polarized beams at the University of Wisconsin, the authors have begun a program to study the weak interaction through the beta decay of polarized nuclei produced in this way. Such experiments bear on tests of CVC in light nuclei, sensitive searches for second-class weak currents, and measurements of the weak vector-coupling constant. One may also deduce the values of certain matrix elements. Our effort is presently centering on a study of the energy dependence of the beta-decay asymmetry of 8 Li
On nuclei and blocking sets in Desarguesian spaces
Ball, S.M.
1999-01-01
A generalisation is given to recent results concerning the possible number of nuclei to a set of points inPG(n, q). As an application of this we obtain new lower bounds on the size of at-fold blocking set ofAG(n, q) in the case (t, q)>1.
Multifragmentation of hot nuclei
International Nuclear Information System (INIS)
Tamain, B.
1990-10-01
It is difficult to deposit a large amount (∼ 1 Gev) of excitation energy into a nucleus. And if one wants to deposit large excitation energy values, the best way consists of shooting a given target nucleus with several nucleons, which can be achieved by using intermediate energy (10-100 MeV/nucleon) heavy ions. Such very excited objects were named hot nuclei. The study of hot nuclei has been undertaken only for 7 years because intermediate energy heavy ion facilities were not available before. The game is then to determine the decay properties of such nuclei, their limits of existence. Their study is connected with general properties of nuclear matter: namely its equation of state. Of special interest, is the onset of a new decay mechanism: multifragmentation, which is the non-sequential disassembly of a hot nucleus into several light nuclei (often called intermediate-mass fragments or IMF) or particles. This paper, shows how this mechanism can reflect fundamental properties of nuclear matter, but also how its experimental signature is difficult to establish. Multifragmentation has also been studied by using very energetic projectiles (protons and heavy ions) in the relativistic or ultra-relativistic region. The multifragmentation question of hot nuclei is far from being solved. One knows that IMF production increases when the excitation energy brought into a system is strongly increased, but very little is known about the mechanisms involved and a clear onset for multifragmentation is not established
International Nuclear Information System (INIS)
Tezuka, Hirokazu.
1984-10-01
Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)
International Nuclear Information System (INIS)
Clark, R.M.
2004-01-01
It has been suggested that a change of nuclear shape may be described in terms of a phase transition and that specific nuclei may lie close to the critical point of the transition. Analytical descriptions of such critical-point nuclei have been introduced recently and they are described briefly. The results of extensive searches for possible examples of critical-point behavior are presented. Alternative pictures, such as describing bands in the candidate nuclei using simple ΔK = 0 and ΔK = 2 rotational-coupling models, are discussed, and the limitations of the different approaches highlighted. A possible critical-point description of the transition from a vibrational to rotational pairing phase is suggested
International Nuclear Information System (INIS)
Rho, M.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette
1983-01-01
Some features of quark degrees of freedom in nuclei are discussed in the light of recent developments in QCD. The principal aim of this talk is to propose, and give a tentative support to, the motion that one can study through nuclear matter different facets of the vacuum structure implied by quantum chromodynamics (QCD). This will be done using the recent (exciting) results obtained in particle physics, in particular lattice gauge calculations. Relevance of this aspect of problem to quark degrees of freedom as well as meson degrees of freedom in nuclei will be discussed. (orig.)
Disintegration of comet nuclei
Ksanfomality, Leonid V.
2012-02-01
The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies.
International Nuclear Information System (INIS)
2002-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on kinematic separation and mass analysis of heavy recoiling nuclei, dynamical effects prior to heavy ion fusion, VACTIV-DELPHI graphical dialog based program for the analysis of gamma-ray spectra, irradiation of nuclear emulsions in relativistic beams of 6 He and 3 H nuclei, optical and structural investigations of PLZT x/65/35 (x = 4, 8 %) ferroelectric ceramics irradiated by a high-current pulsed electron beam, the oscillating charge and first evidence for neutrinoless double beta decay
International Nuclear Information System (INIS)
2001-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on physics from extra dimensions, new physics in the new millennium with GENIUS: double beta decay, dark matter, solar neutrinos, the (μ - , e + ) conversion in nuclei mediated by light Majorana neutrinos, exotic muon-to-positron conversion in nuclei: partial transition sum evaluation by using shell model, solar neutrino problem accounting for self consistent magnetohydrodynamics solution for solar magnetic fields, first neutrino observations from the Sudbury neutrino observatory and status report on BOREXINO and results of the muon-background measurements at CERN
International Nuclear Information System (INIS)
Bohr, A.
1976-01-01
Nuclear structure theories are reviewed concerned with nuclei rotational motion. The development of the deformed nucleus model facilitated a discovery of rotational spectra of nuclei. Comprehensive verification of the rotational scheme and a successful classification of corresponding spectra stimulated investigations of the rotational movement dynamics. Values of nuclear moments of inertia proved to fall between two marginal values corresponding to rotation of a solid and hydrodynamic pattern of an unrotating flow, respectively. The discovery of governing role of the deformation and a degree of a symmetry violence for determining rotational degrees of freedon is pointed out to pave the way for generalization of the rotational spectra
Kaon interactions with very light nuclei
International Nuclear Information System (INIS)
Gibson, B.F.
1979-01-01
Low energy kaon interactions (both K and anti K) with very light nuclei are reviewed. Limitations upon present K-nucleus studies due to uncertainties in the K-N amplitudes are emphasized along with promising uses. A brief review of some of the many interesting aspects of anti K-nucleus scattering is given. Comparison of the limited anti K-d and anti K- 4 He elastic data with theory is made. The anti Kd → πΛp reaction is discussed including the possible ΣN virtual bound state. 49 references
New excitation modes in halo nuclei
International Nuclear Information System (INIS)
Sagawa, H.
1992-01-01
Multipole resonances in exotic neutron-rich nuclei are addressed on the basis of microscopic calculations, i.e., in the framework of the self-consistent H-F + RPA theory. A bunch of resonances with multipoles J π = 0 + , 1 - and 2 + is found near the particle threshold E x ∼ 1 MeV in 10 He having significant portions of the sum rule values and narrow widths. The long tail of the loosely-bound neutrons is the cause of the threshold anomaly of these resonances
Fusion and reactions of exotic nuclei
Directory of Open Access Journals (Sweden)
Sánchez-Benítez A.M.
2011-10-01
Full Text Available Close to the drip lines, the scattering cross sections of halo nuclei show a different behaviour as compared to the tightly bound projectiles of the stability line. Several experiments carried out in the last decade have been dedicated to investigate the competition between transfer, breakup and fusion channels at energies around and below the Coulomb barrier. The rather complex scenario gives rise to conﬂicting conclusions concerning the effect of breakup and transfer on reaction dynamics and the sub-barrier fusion process. In this work we discuss recent experimental ﬁndings in fusion and reactions of 6He halo nucleus at energies around the Coulomb barrier.
Tools for model-independent bounds in direct dark matter searches
DEFF Research Database (Denmark)
Cirelli, M.; Del Nobile, E.; Panci, P.
2013-01-01
We discuss a framework (based on non-relativistic operators) and a self-contained set of numerical tools to derive the bounds from some current direct detection experiments on virtually any arbitrary model of Dark Matter elastically scattering on nuclei.......We discuss a framework (based on non-relativistic operators) and a self-contained set of numerical tools to derive the bounds from some current direct detection experiments on virtually any arbitrary model of Dark Matter elastically scattering on nuclei....
On weakly D-differentiable operators
DEFF Research Database (Denmark)
Christensen, Erik
2016-01-01
Let DD be a self-adjoint operator on a Hilbert space HH and aa a bounded operator on HH. We say that aa is weakly DD-differentiable, if for any pair of vectors ξ,ηξ,η from HH the function 〈eitDae−itDξ,η〉〈eitDae−itDξ,η〉 is differentiable. We give an elementary example of a bounded operator aa......, such that aa is weakly DD-differentiable, but the function eitDae−itDeitDae−itD is not uniformly differentiable. We show that weak DD-differentiability may be characterized by several other properties, some of which are related to the commutator (Da−aD)...
Shell and pairing effects in spherical nuclei close to the nucleon drip lines
International Nuclear Information System (INIS)
Beiner, M.; Lombard, R.J.
1975-01-01
The unstability against nucleon emission of light and medium exotic spherical nuclei is investigated systematically using an extended version of the energy density formalism which reproduces correctly shell and pairing effects in stable nuclei. The reliability of the predictions of this microscopic, self-consistent and weakly parametrized model should not decrease significantly with the distance of the nuclei from the β-stability line, what is not the case for conventional mass formulae or mass tables [fr
Isospin Mixing In N $\\approx$ Z Nuclei
Srnka, D; Versyck, S; Zakoucky, D
2002-01-01
Isospin mixing in N $\\approx$ Z nuclei region of the nuclear chart is an important phenomenon in nuclear physics which has recently gained theoretical and experimental interest. It also forms an important nuclear physics correction in the precise determination of the $ft$-values of superallowed 0$^+ \\rightarrow 0^+ \\beta$- transitions. The latter are used in precision tests of the weak interaction from nuclear $\\beta$- decay. We propose to experimentally measure isospin mixing into nuclear ground states in the N $\\approx$ Z region by determining the isospin forbidden Fermi-component in the Gamow-Teller dominated $J^{\\pi} \\rightarrow J^{\\pi} \\beta$- transitions through the observation of anisotropic positron emission from oriented nuclei. First measurements were carried out with $^{71}$As and are being analyzed now.
International Nuclear Information System (INIS)
Henley, E.M.
1987-01-01
Nuclei are very useful for testing symmetries, and for studies of symmetry breaking. This thesis is illustrated for two improper space-time transformations, parity and time-reversal and for one internal symmetry: charge symmetry and independence. Recent progress and present interest is reviewed. 23 refs., 8 figs., 2 tabs
Transfer involving deformed nuclei
International Nuclear Information System (INIS)
Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.
1985-03-01
Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs
International Nuclear Information System (INIS)
Gulamov, K.G.
1987-01-01
It is well known that interactions of high energy particles with nuclei, owing to possible intranuclear rescatterings, may provide information about the space-time behaviour of the production process. Therefore the main goals of these investigations are related with the attempts to study the space-time process of hadronization of coloured quarks and gluons produced at the initial stage of an interaction to white final state particles and to clarify the influence of composite quark-gluon structure of both the projectile and target on features of the production mechanisms. Since in both the initial and final states of these reactions the authors have strongly interacting multiparticle systems, it is of importance to study the collective properties of these systems. The questions to the point are: what is the degree of collectivization of particles newly produced in collisions with nuclei and what is the influence of the collective nature of a nucleus itself on the production mechanisms, in particular, what are the manifestations of possible multinucleon (multiquark) configurations in nuclei? It is obvious that the reductability of, say, hadron-nucleus (hA) interaction to hadron-nucleon (hN) collisions is directly related to the above problems. Due to time limitations the author discusses here only a few aspects of low p/sub t/ hA interactions which in his opinion are of importance for better understanding of general regularities of collisions with nuclei and for further investigations of the above problems
International Nuclear Information System (INIS)
Laget, J.M.
1988-01-01
This summary is a review of our understanding of nuclei in terms of hadrons exchanging mesons. The open problems are: the determination of the high momentum components of nuclear systems, the role of the three-body forces and the nature of the short range correlations. The ways of studying these problems are discussed
Electromagnetic structure of nuclei
International Nuclear Information System (INIS)
Arnold, R.G.
1986-07-01
A brief review is given of selected topics in the electromagnetic structure of nucleons and nuclei, including nucleon form factors from both quantum chromodynamics and electron scattering data, measurements of the deuteron and triton form factors, quasi-elastic scattering, and the EMC effect. 47 refs., 13 figs
International Nuclear Information System (INIS)
Bohr, A.
1977-01-01
History is surveyed of the development of the theory of rotational states in nuclei. The situation in the 40's when ideas formed of the collective states of a nucleus is evoked. The general rotation theory and the relation between the single-particle and rotational motion are briefly discussed. Future prospects of the rotation theory development are indicated. (I.W.)
International Nuclear Information System (INIS)
Truhlik, E.; Mach, R.
1992-01-01
62 papers and one summary talk were presented at the conference, on subject matters in between nuclear physics (mainly light nuclei) and elementary particle physics, as indicated by the session headings (1) Electroweak nuclear interaction (2) Nuclear physics with pions and antiprotons (3) Nuclear physics with strange particles (4) Relativistic nuclear physics (5) Quark degrees of freedom. (Quittner)
International Nuclear Information System (INIS)
Mittig, W.; Plagnol, E.; Schutz, Y.
1989-11-01
A new simple direct method for the measurement of the total reaction cross section (σ R ) for several light radioactive nuclei (A≤40) is developed. From that, the reduced strong absorption radii (r o 2 ) are obtained. A comparison is made with data obtained by other techniques. A strong isospin dependence of the nuclear radii is observed. (L.C.) [pt
International Nuclear Information System (INIS)
Harris, J.
1986-01-01
The book on particles, imaging and nuclei is one of the Background Readers for the Revised Nuffield Advanced Physics course. The contents contain five educational articles, which extend concepts covered in the course and examine recent developments in physics. Four of the articles on:- particles and the forces of nature, radioisotopes, lasers probe the atomic nucleus, and nuclear history, are indexed separately. (UK)
EMC and polarized EMC effects in nuclei
Energy Technology Data Exchange (ETDEWEB)
Cloet, I.C. [Special Research Centre for the Subatomic Structure of Matter and Department of Physics and Mathematical Physics, University of Adelaide, SA 5005 (Australia); Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)]. E-mail: icloet@jlab.org; Bentz, W. [Department of Physics, School of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292 (Japan)]. E-mail: bentz@keyaki.cc.u-tokai.ac.jp; Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)]. E-mail: awthomas@jlab.org
2006-11-09
We determine nuclear structure functions and quark distributions for {sup 7}Li, {sup 11}B, {sup 15}N and {sup 27}Al. For the nucleon bound state we solve the covariant quark-diquark equations in a confining Nambu-Jona-Lasinio model, which yields excellent results for the free nucleon structure functions. The nucleus is described using a relativistic shell model, including mean scalar and vector fields that couple to the quarks in the nucleon. The nuclear structure functions are then obtained as a convolution of the structure function of the bound nucleon with the light-cone nucleon distributions. We find that we are readily able to reproduce the EMC effect in finite nuclei and confirm earlier nuclear matter studies that found a large polarized EMC effect.
Weak-interaction rates in stellar conditions
Sarriguren, Pedro
2018-05-01
Weak-interaction rates, including β-decay and electron captures, are studied in several mass regions at various densities and temperatures of astrophysical interest. In particular, we study odd-A nuclei in the pf-shell region, which are involved in presupernova formations. Weak rates are relevant to understand the late stages of the stellar evolution, as well as the nucleosynthesis of heavy nuclei. The nuclear structure involved in the weak processes is studied within a quasiparticle proton-neutron random-phase approximation with residual interactions in both particle-hole and particle-particle channels on top of a deformed Skyrme Hartree-Fock mean field with pairing correlations. First, the energy distributions of the Gamow-Teller strength are discussed and compared with the available experimental information, measured under terrestrial conditions from charge-exchange reactions. Then, the sensitivity of the weak-interaction rates to both astrophysical densities and temperatures is studied. Special attention is paid to the relative contribution to these rates of thermally populated excited states in the decaying nucleus and to the electron captures from the degenerate electron plasma.
Relativistic shifts of bound negative-muon precession frequencies
International Nuclear Information System (INIS)
Brewer, J.H.; Froese, A. M.; Fryer, B.A.; Ghandi, K.
2005-01-01
High-field negative-muon spin precession experiments have been performed using a backward-muon beam with substantial transverse spin polarization, facilitating high-precision measurements of the magnetogyric ratio of negative muons bound to nuclei in the ground states of muonic atoms. These results may provide a testing ground for quantum electrodynamics in very strong electromagnetic fields
Direct detection of dark matter bound to the Earth
DEFF Research Database (Denmark)
Catena, Riccardo; Kouvaris, Chris
2017-01-01
We study the properties and direct detection prospects of an as of yet neglected population of dark matter (DM) particles moving in orbits gravitationally bound to the Earth. This DM population is expected to form via scattering by nuclei in the Earth's interior. We compute fluxes and nuclear...
International Nuclear Information System (INIS)
Moretto, L.G.; Wozniak, G.J.
1988-11-01
The formation of hot compound nuclei in intermediate-energy heavy ion reactions is discussed. The statistical decay of such compound nuclei is responsible for the abundant emission of complex fragments and high energy gamma rays. 43 refs., 23 figs
Isotope shifts in unstable nuclei
International Nuclear Information System (INIS)
Rebel, H.
1980-05-01
Current experimental investigations of isotope shifts in atomic spectra of unstable nuclei and the resulting information about size and shape of nuclei far off stability are discussed with reference to some representative examples. (orig.)
UNOBSCURED TYPE 2 ACTIVE GALACTIC NUCLEI
International Nuclear Information System (INIS)
Shi, Yong; Rieke, George H.; Smith, Paul; Donley, Jennifer; Schmidt, Gary; Diamond-Stanic, Aleksandar M.; Rigby, Jane; Hines, Dean
2010-01-01
Type 2 active galactic nuclei (AGNs) with intrinsically weak broad emission lines (BELs) would be exceptions to the unified model. After examining a number of proposed candidates critically, we find that the sample is contaminated significantly by objects with BELs of strengths indicating that they actually contain intermediate-type AGNs, plus a few Compton-thick sources as revealed by extremely low ratios of X-ray to nuclear IR luminosities. We develop quantitative metrics that show two (NGC 3147 and NGC 4594) of the remaining candidates to have BELs 2-3 orders of magnitude weaker than those of typical type 1 AGNs. Several more galaxies remain as candidates to have anomalously weak BELs, but this status cannot be confirmed with the existing information. Although the parent sample is poorly defined, the two confirmed objects are well under 1% of its total number of members, showing that the absence of a BEL is possible, but very uncommon in AGN. We evaluate these two objects in detail using multi-wavelength measurements including new IR data obtained with Spitzer and ground-based optical spectropolarimeteric observations. They have little X-ray extinction with N H 21 cm -2 . Their IR spectra show strong silicate emission (NGC 4594) or weak aromatic features on a generally power-law continuum with a suggestion of silicates in emission (NGC 3147). No polarized BEL is detected in NGC 3147. These results indicate that the two unobscured type 2 objects have circumnuclear tori that are approximately face-on. Combined with their X-ray and optical/UV properties, this behavior implies that we have an unobscured view of the nuclei and thus that they have intrinsically weak BELs. We compare their properties with those of the other less-extreme candidates. We then compare the distributions of bolometric luminosities and accretion rates of these objects with theoretical models that predict weak BELs.
Energetic Nuclei, Superdensity and Biomedicine
Baldin, A. M.
1977-01-01
High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…
Supergravity and upper bound on scale of supersymmetry breaking
International Nuclear Information System (INIS)
Kim, J.E.; Nishino, H.
1983-09-01
In locally supersymmetric grand unified models we show rather a model independent upper bound 3x10 11 GeV for the scale of supersymmetry breaking, which is derived by considering SU(2)xU(1) breaking at electro-weak mass scale. This bound necessarily implies the existence of new particles (superpartners) below 10 4 GeV. (author)
Physical Uncertainty Bounds (PUB)
Energy Technology Data Exchange (ETDEWEB)
Vaughan, Diane Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Preston, Dean L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-03-19
This paper introduces and motivates the need for a new methodology for determining upper bounds on the uncertainties in simulations of engineered systems due to limited fidelity in the composite continuum-level physics models needed to simulate the systems. We show that traditional uncertainty quantification methods provide, at best, a lower bound on this uncertainty. We propose to obtain bounds on the simulation uncertainties by first determining bounds on the physical quantities or processes relevant to system performance. By bounding these physics processes, as opposed to carrying out statistical analyses of the parameter sets of specific physics models or simply switching out the available physics models, one can obtain upper bounds on the uncertainties in simulated quantities of interest.
Shell model calculations for exotic nuclei
International Nuclear Information System (INIS)
Brown, B.A.; Wildenthal, B.H.
1991-01-01
A review of the shell-model approach to understanding the properties of light exotic nuclei is given. Binding energies including p and p-sd model spaces and sd and sd-pf model spaces; cross-shell excitations around 32 Mg, including weak-coupling aspects and mechanisms for lowering the ntw excitations; beta decay properties of neutron-rich sd model, of p-sd and sd-pf model spaces, of proton-rich sd model space; coulomb break-up cross sections are discussed. (G.P.) 76 refs.; 12 figs
International Nuclear Information System (INIS)
Son, Mi Jung; Park, Jin Han; Lim, Ki Moon
2007-01-01
We introduce a new class of functions called weakly clopen function which includes the class of almost clopen functions due to Ekici [Ekici E. Generalization of perfectly continuous, regular set-connected and clopen functions. Acta Math Hungar 2005;107:193-206] and is included in the class of weakly continuous functions due to Levine [Levine N. A decomposition of continuity in topological spaces. Am Math Mon 1961;68:44-6]. Some characterizations and several properties concerning weakly clopenness are obtained. Furthermore, relationships among weak clopenness, almost clopenness, clopenness and weak continuity are investigated
Vaidman, L.
2017-10-01
Recent controversy regarding the meaning and usefulness of weak values is reviewed. It is argued that in spite of recent statistical arguments by Ferrie and Combes, experiments with anomalous weak values provide useful amplification techniques for precision measurements of small effects in many realistic situations. The statistical nature of weak values is questioned. Although measuring weak values requires an ensemble, it is argued that the weak value, similarly to an eigenvalue, is a property of a single pre- and post-selected quantum system. This article is part of the themed issue `Second quantum revolution: foundational questions'.
Interaction of slow pions with atomic nuclei
International Nuclear Information System (INIS)
Troitskij, M.A.; Tsybul'nikov, A.V.; Chekunaev, N.I.
1984-01-01
Interactions of slow pions with atomic nuclei near to pion condensation are investigated. From comparison of experimental data with the theoretical calculation results on the basis of precise microscopic approach not bound with the random phase approximation (RPA) nuclear matter fundamental parameters near a critical point can be found. Optical potential of slow pions in nuclei, πN-scattering amplitudes and lengths, π-atom level isotopic shift, phenomenon of single-nucleon pion absorption by nucleus, phenomenon of nuclear critical opalescence are considered. The results of πN-scattering lengths calculation, sup(40-44)Ca, sup(24-29)Mg, sup(16-18)O π-atom level shift are presented. It is shown that the presence of π-condensate in nuclei can explain the observed suppression of p-wave potential terms. The phenomenon of single-nucleon pion absorption by nucleus is one of direct experiments which permits to reveal the π-condensate. The nuclear opalescence phenomenon is manifested in increase of pion photoproduction reaction cross section for account of nucleus proximity to π-condensation as compared with the calculated in the Fermi-gas model. The suggested method for calculating precondensate phenomena operates the better, the nearer is the system to the condensation threshold whereas the RPA method in this region is inapplicable
International Nuclear Information System (INIS)
Inoue, J.; Ohtaka, K.
2004-01-01
We study virtual bound states in photonics, which are a vectorial extension of electron virtual bound states. The condition for these states is derived. It is found that the Mie resonant state which satisfies the condition that the size parameter is less than the angular momentum should be interpreted as a photon virtual bound state. In order to confirm the validity of the concept, we compare the photonic density of states, the width of which represents the lifetime of the photon virtual bound states, with numerical results
DEFF Research Database (Denmark)
Emiris, Ioannis Z.; Mourrain, Bernard; Tsigaridas, Elias
2010-01-01
) resultant by means of mixed volume, as well as recent advances on aggregate root bounds for univariate polynomials, and are applicable to arbitrary positive dimensional systems. We improve upon Canny's gap theorem [7] by a factor of O(dn-1), where d bounds the degree of the polynomials, and n is the number...... bound on the number of steps that subdivision-based algorithms perform in order to isolate all real roots of a polynomial system. This leads to the first complexity bound of Milne's algorithm [22] in 2D....
Precision measurement of the mass difference between light nuclei and anti-nuclei
Adam, Jaroslav; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahmed, Ijaz; Ahn, Sang Un; Aimo, Ilaria; Aiola, Salvatore; Ajaz, Muhammad; Akindinov, Alexander; Alam, Sk Noor; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Armesto Perez, Nestor; Arnaldi, Roberta; Aronsson, Tomas; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baltasar Dos Santos Pedrosa, Fernando; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Bartke, Jerzy Gustaw; Bartsch, Esther; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batista Camejo, Arianna; Batyunya, Boris; Batzing, Paul Christoph; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Belmont Iii, Ronald John; Belmont Moreno, Ernesto; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhat, Inayat Rasool; Bhati, Ashok Kumar; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biswas, Saikat; Bjelogrlic, Sandro; Blanco, Fernando; Blau, Dmitry; 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Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grynyov, Borys; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerzoni, Barbara; Gulbrandsen, Kristjan Herlache; Gulkanyan, Hrant; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Haake, Rudiger; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harris, John William; Hartmann, Helvi; Harton, Austin Vincent; Hatzifotiadou, Despina; Hayashi, Shinichi; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hilden, Timo Eero; Hillemanns, Hartmut; Hippolyte, Boris; Hristov, Peter Zahariev; Huang, Meidana; Humanic, Thomas; Hussain, Nur; Hussain, Tahir; Hutter, Dirk; Hwang, Dae Sung; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Ionita, Costin; Ippolitov, Mikhail; 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Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhlheim, Daniel Michael; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Mulligan, James Declan; Gameiro Munhoz, Marcelo; Murray, Sean; Musa, Luciano; Musinsky, Jan; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Naru, Muhammad Umair; Nattrass, Christine; Nayak, Kishora; Nayak, Tapan Kumar; Nazarenko, Sergey; Nedosekin, Alexander; Nellen, Lukas; Ng, Fabian; Nicassio, Maria; Niculescu, Mihai; Niedziela, Jeremi; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Norman, Jaime; Nyanin, Alexander; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Ohlson, Alice Elisabeth; Okatan, Ali; Okubo, Tsubasa; Olah, Laszlo; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Oliver, Michael Henry; Onderwaater, Jacobus; Oppedisano, Chiara; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Ozdemir, Mahmut; Pachmayer, Yvonne Chiara; Pagano, Paola; Paic, Guy; Pajares Vales, Carlos; Pal, Susanta Kumar; Pan, Jinjin; Pandey, Ashutosh Kumar; Pant, Divyash; Papikyan, Vardanush; Pappalardo, Giuseppe; Pareek, Pooja; Park, Woojin; Parmar, Sonia; Passfeld, Annika; Paticchio, Vincenzo; Paul, Biswarup; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitry Yurevich; Perez Lara, Carlos Eugenio; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petrov, Viacheslav; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Porteboeuf, Sarah Julie; Porter, R Jefferson; Pospisil, Jan; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Punin, Valery; Putschke, Jorn Henning; Qvigstad, Henrik; Rachevski, Alexandre; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Razazi, Vahedeh; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reed, Rosi Jan; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reicher, Martijn; Reidt, Felix; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riabov, Viktor; Ricci, Renato Angelo; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-Lucian; Rivetti, Angelo; Rocco, Elena; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roeed, Ketil; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Romita, Rosa; Ronchetti, Federico; Ronflette, Lucile; Rosnet, Philippe; Rossi, Andrea; Roukoutakis, Filimon; Roy, Ankhi; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Sadovskiy, Sergey; Safarik, Karel; Sahlmuller, Baldo; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Saleh, Mohammad Ahmad; Salgado Lopez, Carlos Alberto; Salzwedel, Jai Samuel Nielsen; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Santagati, Gianluca; Sarkar, Debojit; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schuchmann, Simone; Schukraft, Jurgen; Schulc, Martin; Schuster, Tim Robin; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Rebecca Michelle; Seeder, Karin Soraya; Seger, Janet Elizabeth; Sekiguchi, Yuko; Selyuzhenkov, Ilya; Senosi, Kgotlaesele; Seo, Jeewon; Serradilla Rodriguez, Eulogio; Sevcenco, Adrian; Shabanov, Arseniy; Shabetai, Alexandre; Shadura, Oksana; Shahoyan, Ruben; Shangaraev, Artem; Sharma, Ankita; Sharma, Natasha; Shigaki, Kenta; Shtejer Diaz, Katherin; Sibiryak, Yury; Siddhanta, Sabyasachi; Sielewicz, Krzysztof Marek; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine Micaela; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Slupecki, Maciej; Smirnov, Nikolai; Snellings, Raimond; Snellman, Tomas Wilhelm; Soegaard, Carsten; Soltz, Ron Ariel; Song, Jihye; Song, Myunggeun; Song, Zixuan; Soramel, Francesca; Sorensen, Soren Pontoppidan; Spacek, Michal; Spiriti, Eleuterio; Sputowska, Iwona Anna; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Steinpreis, Matthew Donald; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Sultanov, Rishat; Sumbera, Michal; Symons, Timothy; Szabo, Alexander; Szanto De Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szymanski, Maciej Pawel; Takahashi, Jun; Tanaka, Naoto; Tangaro, Marco-Antonio; Tapia Takaki, Daniel Jesus; Tarantola Peloni, Attilio; Tariq, Mohammad; Tarzila, Madalina-Gabriela; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terasaki, Kohei; Terrevoli, Cristina; Teyssier, Boris; Thaeder, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony Robert; Toia, Alberica; Trogolo, Stefano; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; Van Der Maarel, Jasper; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vanat, Tomas; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vechernin, Vladimir; Veen, Annelies Marianne; Veldhoen, Misha; Velure, Arild; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara Limon, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Vislavicius, Vytautas; Viyogi, Yogendra; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Vranic, Danilo; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Jan; Wang, Hongkai; Wang, Mengliang; Wang, Yifei; Watanabe, Daisuke; Weber, Michael; Weber, Steffen Georg; Wessels, Johannes Peter; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Williams, Crispin; Windelband, Bernd Stefan; Winn, Michael Andreas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Ping; Yano, Satoshi; Yasnopolskiy, Stanislav; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-Kwon; Yurchenko, Volodymyr; Yushmanov, Igor; Zaborowska, Anna; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correia Zanoli, Henrique Jose; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhang, Yonghong; Zhao, Chengxin; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zyzak, Maksym
2015-08-17
The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. This force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons (d) and anti-deuterons ($\\bar{d}$), and $^{3}{\\rm He}$ and $^3\\overline{\\rm He}$ nuclei carried out with the ALICE (A Large Ion Collider Experiment) detector in Pb-Pb collisions at a centre-of-mass energy per nucleon pair of 2.76 TeV. Our direct measurement of the mass-over-charge differences confirm CPT invariance to an unprecedented precision in the sector of light nuclei. This funda...
Disintegration of comet nuclei
International Nuclear Information System (INIS)
Ksanfomality, Leonid V
2012-01-01
The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies. (physics of our days)
International Nuclear Information System (INIS)
Huefner, J.
1975-01-01
Are pions a good tool to study nuclei. If the emphasis of this question rests on ''tool'', the answer must be ''not yet.'' The reason: one does not even understand how a pion interacts with a nucleus. This is part of the many-body problem for strongly interacting particles and its study is a basic problem in physics. One must investigate questions like: Can one understand pion-nucleus interactions from pion-nucleon physics. How does a Δ-resonance look in nuclei. Once one has solved those basic problems, there will be spinoffs in medical, technical and nuclear areas. Then pions can be used as a tool to study nuclear properties
International Nuclear Information System (INIS)
Whelan, N.D.
1993-01-01
Random Matrix Theory successfully describes the statistics of the low-lying spectra of some nuclei but not of others. It is currently believed that this theory applies to systems in which the corresponding classical motion is chaotic. This conjecture is tested for collective nuclei by studying the Interacting Boson Model. Quantum and classical measures of chaos are proposed and found to be in agreement throughout the parameter space of the model. For some parameter values the measures indicate the presence of a previously unknown approximate symmetry. A phenomenon called partial dynamical symmetry is explored and shown to lead to a suppression of chaos. A time dependent function calculated from the quantum spectrum is discussed. This function is sensitive to the extent of chaos and provides a robust method of analyzing experimental spectra
International Nuclear Information System (INIS)
Mitchel, G.; Shriner, J.
2005-01-01
Although the predictions of Random Matrix Theory (RMT) were available by the early 1960s, data of sufficiently high quality to adequately test the theory were only obtained a decade later by Rainwater. It was another decade later that Bohigas, Haq and Pandey combined the best available nuclear resonance data - the Columbia neutron resonances in heavy nuclei and the TUNL proton resonances in lighter nuclei - to form the Nuclear Data Ensemble. They obtained excellent agreement for the level statistics with the RMT predictions. The expected Porter-Thomas (PT) distribution was considered very early. However, since the widths (amplitudes squared) are measured, the predicted Gaussian distribution for the amplitudes was only qualitatively confirmed. A much more sensitive test was performed by measuring two widths and the relative phase between the two amplitudes. By comparison of the width and amplitude correlations, the Gaussian distribution was confirmed at the 1% level. Following the Bohigas conjecture - that quantum analogs of classically chaotic systems obey RMT - there was an explosion of activity utilizing level statistics in many different quantum systems. In nuclei the focus was verifying the range of applicability of RMT. Of particular interest was the effect of collectivity and of excitation energy on statistical properties. The effect of symmetry breaking on level statistics was examined and early predictions by Dyson were confirmed. The effect of symmetry breaking on the width distribution was also measured for the first time. Although heuristic arguments predicted no change from the PT distribution, experimentally there was a large deviation from the PT prediction. Later theoretical efforts were consistent with this result. The stringent conditions placed on the experiments - for eigenvalue tests the data need to be essentially perfect (few or no missing levels or mis assigned quantum numbers) - has limited the amount of suitable experimental data. The
International Nuclear Information System (INIS)
Hamilton, J.H.
1987-01-01
Discoveries of many different types of nuclear shape coexistence are being found at both low and high excitation energies throughout the periodic table, as documented in recent reviews. Many new types of shape coexistence have been observed at low excitation energies, for examples bands on more than four different overlapping and coexisting shapes are observed in 185 Au, and competing triaxial and prolate shapes in 71 Se and 176 Pt. Discrete states in super-deformed bands with deformations β 2 ∼ 0.4-0.6, coexisting with other shapes, have been seen to high spin up to 60ℎ in 152 Dy, 132 Ce and 135 Nd. Super-deformed nuclei with N and Z both around 38 and around Z = 38, N ≥ 60. These data led to the discovery of new shell gaps and magic numbers of 38 for N and Z and 60 for N but now for deformed shapes. Marked differences in structure are observed at spins of 6 to 20 in nuclei in this region, which differ by only two protons; for example, 68 Ge and 70 Se. The differences are thought to be related to the competing shell gaps in these nuclei
Elusive active galactic nuclei
Maiolino, R.; Comastri, A.; Gilli, R.; Nagar, N. M.; Bianchi, S.; Böker, T.; Colbert, E.; Krabbe, A.; Marconi, A.; Matt, G.; Salvati, M.
2003-10-01
A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically `elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive active galactic nuclei (AGN) in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 1024 cm-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical narrow-line region. Elusive AGN may contribute significantly to the 30-keV bump of the X-ray background.
Bounded Gaussian process regression
DEFF Research Database (Denmark)
Jensen, Bjørn Sand; Nielsen, Jens Brehm; Larsen, Jan
2013-01-01
We extend the Gaussian process (GP) framework for bounded regression by introducing two bounded likelihood functions that model the noise on the dependent variable explicitly. This is fundamentally different from the implicit noise assumption in the previously suggested warped GP framework. We...... with the proposed explicit noise-model extension....
Bounded Intention Planning Revisited
Sievers Silvan; Wehrle Martin; Helmert Malte
2014-01-01
Bounded intention planning provides a pruning technique for optimal planning that has been proposed several years ago. In addition partial order reduction techniques based on stubborn sets have recently been investigated for this purpose. In this paper we revisit bounded intention planning in the view of stubborn sets.
Effective interactions and coupling schemes in nuclei
International Nuclear Information System (INIS)
Talmi, I.
1994-01-01
Eigenstates of the shell model are obtained by diagonalization of the Hamiltonian submatrix defined by a given shell model subspace. Matrix elements of the effective nuclear interaction can be determined from experiment in a consistent way. This approach was introduced in 1956 with the 38 Cl- 40 K spectra, has been applied in many cases and its latest success is in the s, d shell. This way, general features of the effective interaction have been determined. The T=1 interaction is diagonal in the seniority scheme as clearly demonstrated in proton 1g 9/2 n and 1h 11/2 n configurations and in the description of semimagic nuclei by generalized seniority. Apart from a strong and attractive pairing term, T=1 interactions are repulsive on the average. The T=0 interaction is attractive and is the origin of the central potential well in which nucleons are bound. It breaks seniority in a major way leading to deformed nuclei and rotational spectra. Such an interaction may be approximated by a quadrupole-quadrupole interaction which is the basis of the interacting boson model. Identical nucleons with pairing and quadrupole interactions cannot be models of actual nuclei. Symmetry properties of states with maximum T are very different from those of ground states of actual nuclei. The T=1 interaction between identical nucleons cannot be approximated by pairing and quadrupole interactions. The rich variety of nuclear spectra is due to the competition between seniority conserving T=1 interactions and the T=0 quadrupole interaction between protons and neutrons. (orig.)
Bounding species distribution models
Directory of Open Access Journals (Sweden)
Thomas J. STOHLGREN, Catherine S. JARNEVICH, Wayne E. ESAIAS,Jeffrey T. MORISETTE
2011-10-01
Full Text Available Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for “clamping” model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART and maximum entropy (Maxent models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5: 642–647, 2011].
Bounding Species Distribution Models
Stohlgren, Thomas J.; Jarnevich, Cahterine S.; Morisette, Jeffrey T.; Esaias, Wayne E.
2011-01-01
Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5): 642-647, 2011].
Weak interaction studies from nuclear beta decay
International Nuclear Information System (INIS)
Morita, M.
1981-01-01
The studies performed at the theoretical nuclear physics division of the Laboratory of Nuclear Studies, Osaka University, are reported. Electron spin density and internal conversion process, nuclear excitation by electron transition, beta decay, weak charged current, and beta-ray angular distributions in oriented nuclei have been studied. The relative intensity of internal conversion electrons for the case in which the radial wave functions of orbital electrons are different for electron spin up and down was calculated. The calculated value was in good agreement with the experimental one. The nuclear excitation following the transition of orbital electrons was studied. The calculated probability of the nuclear excitation of Os 189 was 1.4 x 10 - 7 in conformity with the experimental value 1.7 x 10 - 7 . The second class current and other problems on beta-decay have been extensively studied, and described elsewhere. Concerning weak charged current, the effects of all induced terms, the time component of main axial vector, all partial waves of leptons, Coulomb correction for the electrons in finite size nuclei, and radiative correction were studied. The beta-ray angular distribution for the 1 + -- 0 + transition in oriented B 12 and N 12 was investigated. In this connection, investigation on the weak magnetism to include all higher order corrections for the evaluation of the spectral shape factors was performed. Other works carried out by the author and his collaborators are also explained. (Kato, T.)
Partial Widths of Nonmesonic Weak Decays of Lambda-Hypernuclei
Kuzmin, V A
2002-01-01
It is shown that the phenomenological matrix elements completely describing \\Lambda N \\to NN weak interaction in the 1p-shell nuclei can be obtained from the partial widths of nonmesonic decays of ^{10}_{\\Lambda}Be and ^{10}_{\\Lambda}B hypernuclei. It is shown that the uncertainties related to the description of nuclear structure are not essential for this task.
International Nuclear Information System (INIS)
Santachiara, G.; Di Matteo, L.; Belosi, F.; Prodi, F.
2009-01-01
Measurements of ice nuclei (I N) in different size classes of aerosol P M1, P M2.5, PM10, and total suspended particles (Tsp) were performed at a rural site (S.Pietro Capofiume, in the Po Valley, Italy). Simultaneous measurements of particle number concentrations were also made with a condensation nucleus counter (CN C-TSI), along with particle concentration in different size classes starting from diameter d > 0.3 μm (Optical Spectrometer Grimm, Mod.1.108). No correlation is observed between I N and the particle number concentration measured with the condensation nuclei counter, and there is only a weak correlation with the particle concentration measured using the optical counter, thus confirming the contribution of the accumulation and coarse aerosol fraction. A positive correlation is observed between supersaturation with respect to ice and water values and ice nuclei number concentration, and an exponential dependence of I N on temperature is found. In addition, cloud concentration nuclei (C CN) were measured. The present measurements reveal a diurnal trend, with lower values at about midday and higher ones during the night, a similar trend between C CN and the relative humidity, and opposite to the mixing layer height.
Nuclei transmutation by collisions with fast hadrons and nuclei
International Nuclear Information System (INIS)
Strugalski, Z.; Strugalska-Gola, E.; Drzymala, A.
1998-01-01
Atomic nuclei change their mass- and charge-numbers if bombarded by fast hadrons and nuclei; the transmutation appears as a complicated process. It proceeds in a definite way - through a few stages or phases. Adequate identification of the nucleons and light nuclear fragments emitted and evaporated in a hadron-nucleus or nucleus-nucleus collisions and in the collision-induced intranuclear reactions allows one to estimate quantitatively the nuclei transmutations in the various stages (phases) of the process
Gossip and Distributed Kalman Filtering: Weak Consensus Under Weak Detectability
Kar, Soummya; Moura, José M. F.
2011-04-01
The paper presents the gossip interactive Kalman filter (GIKF) for distributed Kalman filtering for networked systems and sensor networks, where inter-sensor communication and observations occur at the same time-scale. The communication among sensors is random; each sensor occasionally exchanges its filtering state information with a neighbor depending on the availability of the appropriate network link. We show that under a weak distributed detectability condition: 1. the GIKF error process remains stochastically bounded, irrespective of the instability properties of the random process dynamics; and 2. the network achieves \\emph{weak consensus}, i.e., the conditional estimation error covariance at a (uniformly) randomly selected sensor converges in distribution to a unique invariant measure on the space of positive semi-definite matrices (independent of the initial state.) To prove these results, we interpret the filtered states (estimates and error covariances) at each node in the GIKF as stochastic particles with local interactions. We analyze the asymptotic properties of the error process by studying as a random dynamical system the associated switched (random) Riccati equation, the switching being dictated by a non-stationary Markov chain on the network graph.
International Nuclear Information System (INIS)
Diabate, S.; Strack, S.
1993-01-01
Tritium released into the environment may be incorporated into organic matter. Organically bound tritium in that case will show retention times in organisms that are considerably longer than those of tritiated water which has significant consequences on dose estimates. This article reviews the most important processes of organically bound tritium production and transport through food networks. Metabolic reactions in plant and animal organisms with tritiated water as a reaction partner are of great importance in this respect. The most important production process, in quantitative terms, is photosynthesis in green plants. The translocation of organically bound tritium from the leaves to edible parts of crop plants should be considered in models of organically bound tritium behavior. Organically bound tritium enters the human body on several pathways, either from the primary producers (vegetable food) or at a higher tropic level (animal food). Animal experiments have shown that the dose due to ingestion of organically bound tritium can be up to twice as high as a comparable intake of tritiated water in gaseous or liquid form. In the environment, organically bound tritium in plants and animals is often found to have higher specific tritium concentrations than tissue water. This is not due to some tritium enrichment effects but to the fact that no equilibrium conditions are reached under natural conditions. 66 refs
Resonance reactions and enhancement of weak interactions in collisions of cold molecules
International Nuclear Information System (INIS)
Flambaum, V. V.; Ginges, J. S. M.
2006-01-01
With the creation of ultracold atoms and molecules, a new type of chemistry - 'resonance' chemistry - emerges: chemical reactions can occur when the energy of colliding atoms and molecules matches a bound state of the combined molecule (Feshbach resonance). This chemistry is rather similar to reactions that take place in nuclei at low energies. In this paper we suggest some problems for future experimental and theoretical work related to the resonance chemistry of ultracold molecules. Molecular Bose-Einstein condensates are particularly interesting because in this system collisions and chemical reactions are extremely sensitive to weak fields; also, a preferred reaction channel may be enhanced due to a finite number of final states. The sensitivity to weak fields arises due to the high density of narrow compound resonances and the macroscopic number of molecules with kinetic energy E=0 (in the ground state of a mean-field potential). The high sensitivity to the magnetic field may be used to measure the distribution of energy intervals, widths, and magnetic moments of compound resonances and study the onset of quantum chaos. A difference in the production rate of right-handed and left-handed chiral molecules may be produced by external electric E and magnetic B fields and the finite width Γ of the resonance (correlation ΓE·B). The same effect may be produced by the parity-violating energy difference in chiral molecules
International Nuclear Information System (INIS)
Gasparian, A.P.
1984-01-01
Results are presented from a bubble chamber experiment to search for anomalous mean free path (MFP) phenomena for secondary multicharged fragments (Zsub(f)=5 and 6) of the beam carbon nucleus at 4.2 GeV/c per nucleon. A total of 50000 primary interactions of carbon with propane (C 3 H 8 ) were created. Approximately 6000 beam tragments with charges Zsub(f)=5 and 6 were analyzed in detail to find out an anomalous decrease of MFP. The anomaly is observed only for secondary 12 C nuclei
International Nuclear Information System (INIS)
2001-01-01
The present collection of letters from JINR, Dubna, contains eight separate records on the interaction of high energy Λ 6 He hypernuclear beams with atomic nuclei, the position-sensitive detector of a high spatial resolution on the basis of a multiwire gas electron multiplier, pseudorapidity hadron density at the LHC energy, high precision laser control of the ATLAS tile-calorimeter module mass production at JINR, a new approach to ECG's features recognition involving neural network, subcriticity of a uranium target enriched in 235 U, beam space charge effects in high-current cyclotron injector CI-5, a homogeneous static gravitational field and the principle of equivalence
Beckmann, Volker
2012-01-01
This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra and XMM Newton not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. The book gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy d
Elementary excitations in nuclei
International Nuclear Information System (INIS)
Lemmer, R.H.
1987-01-01
The role of elementary quasi-particle and quasi-hole excitations is reviewed in connection with the analysis of data involving high-lying nuclear states. This article includes discussions on: (i) single quasi-hole excitations in pick-up reactions, (ii) the formation of single quasi-hole and quasi-particle excitations (in different nuclei) during transfer reactions, followed by (iii) quasi-particle quasi-hole excitations in the same nucleus that are produced by photon absorption. Finally, the question of photon absorption in the vicinity of the elementary Δ resonance is discussed, where nucleonic as well as nuclear degrees of freedom can be excited
International Nuclear Information System (INIS)
2000-01-01
The present collection of letters from JINR, Dubna, contains six separate records on the DELPHI experiment at LEP, the Fermi-surface dynamics of rotating nuclei, production of large samples of the silica dioxide aerogel in the 37-litre autoclave and test of its optical properties, preliminary radiation resource results on scintillating fibers, a new algorithm for the direct transformation method of time to digital with the high time resolution and development and design of analogue read-out electronics for HADES drift chamber system
International Nuclear Information System (INIS)
Baldin, A.M.; Bondarev, V.K.; Golovanov, L.B.
1977-01-01
Limit fragmentation of light nuclei (deuterium, helium) bombarded with 8,6 GeV/c protons was investigated. Fragments (pions, protons and deuterons) were detected within the emission angle 50-150 deg with regard to primary protons and within the pulse range 150-180 MeV/c. By the kinematics of collision of a primary proton with a target at rest the fragments observed correspond to a target mass upto 3 GeV. Thus, the data obtained correspond to teh cumulation upto the third order
Blandford, RD; Woltjer, L
1990-01-01
Starting with this volume, the Lecture Notes of the renowned Advanced Courses of the Swiss Society for Astrophysics and Astronomy will be published annually. In each course, three extensive lectures given by leading experts in their respective fields cover different and essential aspects of the subject. The 20th course, held at Les Diablerets in April 1990, dealt with current research on active galactic nuclei; it represents the most up-to-date views on the subject, presented with particular regard for clarity. The previous courses considered a wide variety of subjects, beginning with ""Theory
We propose an experiment with MINIBALL coupled to T-REX to investigate n-rich $^{95,96}$Rb nuclei by the incomplete fusion reaction of $^{94}$Kr on $^{7}$Li. The nuclei of interest will be populated by transfer of a triton into $^{94}$Kr, forming the excited $^{97}$Rb nucleus, followed by the emission of an alpha particle, which will be detected in the Si telescopes of T-REX. The $^{97}$Rb product will evaporate 1 or 2 (with the highest probability) neutrons leading to $^{96}$Rb or $^{95}$Rb, respectively. The aim of the experiment is twofold: \\\\ i) to perform a $\\gamma$- spectroscopy study of $^{95,96}$Rb nuclei with N=58,59, the structure of which is of particular interest in investigating the transition towards stable deformation at N=60, \\\\ ii) to acquire experience in using incomplete fusion reactions with the weakly bound $^{7}$Li target, in order to perform, at a later stage with HIE-ISOLDE, similar measurements induced by n-rich radioactive beams of Sn and Hg, for which at least 5 MeV/nucleon are need...
Nonmesonic weak decay of the hypertriton
International Nuclear Information System (INIS)
Bennhold, C.; Ramos, A.; Aruliah, D.A.; Oelfke, U.
1992-01-01
The nonmesonic weak decay of Λ 3 H is evaluated microscopically in the pion exchange model. The correlated three-body wave function of the hypertriton is approximated by a bound Λ-deuteron system obtained by averaging the YN interaction over the deuteron wave function. The relevant matrix elements are calculated in momentum space. The resulting decay rate is 4.9% of the free Λ decay rate
Study of 19F and 19Ne mirror nuclei
International Nuclear Information System (INIS)
Lebrun, Claude.
1976-01-01
The electromagnetic properties of the mirror nuclei 19 F and 19 Ne were studied using the 18 O(d,nγ) 19 F, 17 O( 3 He,nγ) 19 Ne and 19 F(p,nγ) 19 Ne reactions. Lifetimes of 8 levels in 19 F and 11 levels in 19 Ne have been measured using the Doppler shift attenuation method. Weak and strong components of M 1 , E 1 and E 2 transition strengths are compared with shell model predictions. M 1 and E 2 transition strengths of conjugated nuclei (A=18 to A=34) are compiled and compared with wide configuration space shell models [fr
International Nuclear Information System (INIS)
Delorme, J.
1978-01-01
The definition and general properties of weak second class currents are recalled and various detection possibilities briefly reviewed. It is shown that the existing data on nuclear beta decay can be consistently analysed in terms of a phenomenological model. Their implication on the fundamental structure of weak interactions is discussed [fr
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.
DEFF Research Database (Denmark)
Lukas, Manuel; Hillebrand, Eric
Relations between economic variables can often not be exploited for forecasting, suggesting that predictors are weak in the sense that estimation uncertainty is larger than bias from ignoring the relation. In this paper, we propose a novel bagging predictor designed for such weak predictor variab...
Strength distributions of electromagnetic transitions in light nuclei
International Nuclear Information System (INIS)
Kostin, V.Ya.; Koval', A.A.; Kopanets, E.G.; Tsytko, S.P.
1980-01-01
Distributions of probabilities of electromagnetic transitions from resonance levels of light nuclei with masses A=Z-40 for eight types of transition (epsilon1, epsilon2, M1, M8, isoscalar and isovector) are obtained. Recommended upper limits (RUL) of transition probabilities are determined for each type of transitions. A comparison with analogous characteristics for transitions between bound states is carried out. It has been causes found that RUL for resonance states substantially differ from RUL for transitions between bound states. Possible causes of such difference are discussed
Exotic nuclei and radioactive beams
International Nuclear Information System (INIS)
Chomaz, P.
1996-01-01
The Nuclei called exotic are all the nuclei that it is necessary to recreate in laboratory to study them. Their life time is too short -in relation to earth age- for it remains enough on earth. The researchers are going to have at their s disposal at GANIL (Caen) with the S.P.I.R.A.L. project, exotic nuclei beams and will study new kinds of nuclear reactions to better understand the atom nucleus. (N.C.). 2 refs., 9 figs
Isolation of Nuclei and Nucleoli.
Pendle, Alison F; Shaw, Peter J
2017-01-01
Here we describe methods for producing nuclei from Arabidopsis suspension cultures or root tips of Arabidopsis, wheat, or pea. These methods could be adapted for other species and cell types. The resulting nuclei can be further purified for use in biochemical or proteomic studies, or can be used for microscopy. We also describe how the nuclei can be used to obtain a preparation of nucleoli.
International Nuclear Information System (INIS)
Nosov, V.G.; Kamchatnov, A.M.
A consistent theory of the shell and magic oscillations of the masses of spherical nuclei is developed on the basis of the Fermi liquid concept of the energy spectrum of nuclear matter. A ''magic'' relationship between the system's dimensions and the limiting momentum of the quasi-particle distribution is derived; an integer number of the de Broglie half-waves falls on the nuclear diameter. An expression for the discontinuity in the nucleon binding energy in the vicinity of a magic nucleus is obtained. The role of the residual interaction is analyzed. It is shown that the width of the Fermi-surface diffuseness due to the residual interaction is proportional to the squared vector of the quasi-particle orbital angular momentum. The values of the corresponding proportionality factors (the coupling constant for quasi particles) are determined from the experimental data for 52 magic nuclei. The rapid drop of the residual interaction with increasing nuclear size is demonstrated. (7 figures, 3 tables) (U.S.)
Stability of superheavy nuclei
Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.
2018-03-01
The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92 ≤Z ≤126 and isospins 40 ≤N -Z ≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N . α -decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted.
Cluster structures in light nuclei
International Nuclear Information System (INIS)
Horiuchi, H.
2000-01-01
Complete text of publication follows. Clustering in neutron-rich nuclei is discussed. To understand the novel features (1,2,3) of the clustering in neutron-rich nuclei, the basic features of the clustering in stable nuclei (4) are briefly reviewed. In neutron-rich nuclei, the requirement of the stability of clusters is questioned and the threshold rule is no more obeyed. Examples of clustering in Be and B isotopes (4,5) are discussed in some detail. Possible existence of novel type of clustering near neutron dripline is suggested (1). (author)
Critical potentials, leptons, and weak currents
International Nuclear Information System (INIS)
Smith, P.F.; Lewin, J.D.
1977-12-01
A theoretical study is made of the interaction of very strong localised electromagnetic potentials with charged leptons, and with the vacuum state. The principal objective is to investigate the phenomena which occur when the potential reaches or exceeds the critical value at which bound levels are drawn into the lower continuum. The behaviour of bound and continuum solutions of the Dirac equation for the specific model of a short range potential well in an arbitrarily large bounded volume is examined in detail. Vacuum polarisation effects are computed by summation over the infinite set of single particle levels, and special attention is given to the behaviour of the overall charge distribution as the potential strength increases through the critical value. The most significant features of the results are (a) the formation of highly localised electron or muon bound states, (b) similar critical potential strengths for electrons and muons, and (c) redefinition of the vacuum by one charge unit at the critical potential. These features are analogous to some properties of leptonic and hadronic weak currents, and the hypothesis is proposed that strong short range potentials may provide a possible mediating mechanism for the weak interaction and also a lepton confinement mechanism within the structure of hadrons. (author)
Weak interaction and nucleus: the relationship keeps on
International Nuclear Information System (INIS)
Martino, J.; Frere, J.M.; Naviliat-Cuncic, O.; Volpe, C.; Marteau, J.; Lhuillier, D.; Vignaud, D.; Legac, R.; Marteau, J.; Legac, R.
2003-01-01
This document gathers the lectures made at the Joliot-Curie international summer school in 2003 whose theme, that year, was the relationship between weak interaction and nucleus. There were 8 contributions whose titles are: 1) before the standard model: from beta decay to neutral currents; 2) the electro-weak theory and beyond; 3) testing of the standard model at low energies; 4) description of weak processes in nuclei; 5) 20.000 tonnes underground, an approach to the neutrino-nucleus interaction; 6) parity violation from atom to nucleon; 7) how neutrinos got their masses; and 8) CP symmetry
Bounded Rationality and Budgeting
Ibrahim, Mukdad
2016-01-01
This article discusses the theory of bounded rationality which had been introduced by Herbert Simon in the 1950s. Simon introduced the notion of bounded rationality stating that while decision-makers strive for rationality, they are limited by the effect of the environment, their information process capacity and by the constraints on their information storage and retrieval capabilities. Moreover, this article tries to specifically blend this notion into budgeting, using the foundations of inc...
Precision spectroscopy of pionic atoms and chiral symmetry in nuclei
International Nuclear Information System (INIS)
Itahashi, Kenta; Ahn, DeukSoon; Berg, Georg P.A.; Dozono, Masanori; Etoh, Daijiro; Fujioka, Hiroyuki; Fukuda, Naoki; Fukunishi, Nobuhisa; Geissel, Hans; Haettner, Emma; Hashimoto, Tadashi; Hayano, Ryugo S.; Hirenzaki, Satoru; Horii, Hiroshi; Ikeno, Natsumi; Inabe, Naoto; Iwasaki, Masahiko; Kameda, Daisuke; Kawase, Shouichiro; Kisamori, Keiichi; Kiyokawa, Yu; Kubo, Toshiyuki; Kusaka, Kensuke; Matsushita, Masafumi; Michimasa, Shin’ichiro; Mishima, Go; Miya, Hiroyuki; Murai, Daichi; Nagahiro, Hideko; Nishi, Takahiro; Ota, Shinsuke; Sakamoto, Naruhiko; Sekiguchi, Kimiko; Suzuki, Hiroshi; Suzuki, Ken; Takaki, Motonobu; Takeda, Hiroyuki; Tanaka, Yoshiki K.; Uesaka, Tomohiro; Wada, Yasumori; Watanabe, Yuni N.; Weick, Helmut; Yamakami, Hiroki; Yanagisawa, Yoshiyuki; Yoshida, Koichi
2016-01-01
We conduct an experimental project to make spectroscopy of deeply bound pionic atoms systematically over wide range of nuclei. We aim at studying the strong interaction in the low energy region, which has close connection to spontaneous chiral symmetry breaking and its partial restoration in nuclear matter. First experimental results show improved spectral resolution and much better statistical sensitivity than previous experiments. Present status of the experiment is reported.
Tate, Stephen James
2013-10-01
In the 1960s, the technique of using cluster expansion bounds in order to achieve bounds on the virial expansion was developed by Lebowitz and Penrose (J. Math. Phys. 5:841, 1964) and Ruelle (Statistical Mechanics: Rigorous Results. Benjamin, Elmsford, 1969). This technique is generalised to more recent cluster expansion bounds by Poghosyan and Ueltschi (J. Math. Phys. 50:053509, 2009), which are related to the work of Procacci (J. Stat. Phys. 129:171, 2007) and the tree-graph identity, detailed by Brydges (Phénomènes Critiques, Systèmes Aléatoires, Théories de Jauge. Les Houches 1984, pp. 129-183, 1986). The bounds achieved by Lebowitz and Penrose can also be sharpened by doing the actual optimisation and achieving expressions in terms of the Lambert W-function. The different bound from the cluster expansion shows some improvements for bounds on the convergence of the virial expansion in the case of positive potentials, which are allowed to have a hard core.
International Nuclear Information System (INIS)
Orzalesi, C.A.
1979-01-01
In relativistic quantum theory, bound states generate forces in the crossed channel; such forces can affect the binding and self-consistent solutions should be sought for the bound-state problem. The author investigates how self-consistency can be achieved by successive approximations, in a simple scalar model and with successive relativistic eikonal approximations (EAs). Within the generalized ladder approximation, some exact properties of the resulting ''first generation'' bound states are discussed. The binding energies in this approximation are rather small even for rather large values of the primary coupling constant. The coupling of the constituent particles to the first-generation reggeon is determined by a suitable EA and a new generalized ladder amplitude is constructed with rungs given either by the primary gluons or by the first-generation reggeons. The resulting new (second-generation) bound states are found in a reggeized EA. The size of the corrections to the binding energies due to the rebinding effects is surprisingly large. The procedure is then iterated, so as to find - again in an EA - the third-generation bound states. The procedure is found to be self-consistent already at this stage: the third-generation bound states coincide with those of second generation, and no further rebinding takes place in the higher iterations of the approximation method. Features - good and bad - of the model are discussed, as well as the possible relevance of rebinding mechanisms in hadron dynamics. (author)
Level structures in Yb nuclei far from stable nuclei
International Nuclear Information System (INIS)
Hashizume, Akira
1982-01-01
Applying n-γ, γ-γ coincidence techniques, the excited levels in 158 Yb and in 157 Yb nuclei were studied. Stress is placed ona neutron detection technique to assign (HI,xn) reactions which produce the nuclei far from β stability line. (author)
International Nuclear Information System (INIS)
Ngo, C.
1986-11-01
Experimental indications leading to the thought of a very excited nucleus fragmentation are resumed. Theoretical approaches are briefly described; they are used to explain the phenomenon in showing off they are based on a minimum information principle. This model is based on time dependent Thomas-Fermi calculation which allows the mean field effect description, and with a site-bound percolation model which allows the fluctuation description [fr
International Nuclear Information System (INIS)
Deshpande, N.G.
1980-01-01
By electro-weak theory is meant the unified field theory that describes both weak and electro-magnetic interactions. The development of a unified electro-weak theory is certainly the most dramatic achievement in theoretical physics to occur in the second half of this century. It puts weak interactions on the same sound theoretical footing as quantum elecrodynamics. Many theorists have contributed to this development, which culminated in the works of Glashow, Weinberg and Salam, who were jointly awarded the 1979 Nobel Prize in physics. Some of the important ideas that contributed to this development are the theory of beta decay formulated by Fermi, Parity violation suggested by Lee and Yang, and incorporated into immensely successful V-A theory of weak interactions by Sudarshan and Marshak. At the same time ideas of gauge invariance were applied to weak interaction by Schwinger, Bludman and Glashow. Weinberg and Salam then went one step further and wrote a theory that is renormalizable, i.e., all higher order corrections are finite, no mean feat for a quantum field theory. The theory had to await the development of the quark model of hadrons for its completion. A description of the electro-weak theory is given
Efficient quantum computing with weak measurements
International Nuclear Information System (INIS)
Lund, A P
2011-01-01
Projective measurements with high quantum efficiency are often assumed to be required for efficient circuit-based quantum computing. We argue that this is not the case and show that the fact that they are not required was actually known previously but was not deeply explored. We examine this issue by giving an example of how to perform the quantum-ordering-finding algorithm efficiently using non-local weak measurements considering that the measurements used are of bounded weakness and some fixed but arbitrary probability of success less than unity is required. We also show that it is possible to perform the same computation with only local weak measurements, but this must necessarily introduce an exponential overhead.
Electron scattering off nuclei
International Nuclear Information System (INIS)
Gattone, A.O.
1989-01-01
Two recently developed aspects related to the scattering of electrons off nuclei are presented. On the one hand, a model is introduced which emphasizes the relativistic aspects of the problem in the impulse approximation, by demanding strict maintenance of the algebra of the Poincare group. On the other hand, the second model aims at a more sophisticated description of the nuclear response in the case of collective excitations. Basically, it utilizes the RPA formalism with a new development which enables a more careful treatment of the states in the continuum as is the case for the giant resonances. Applications of both models to the description of elastic scattering, inelastic scattering to discrete levels, giant resonances and the quasi-elastic region are discussed. (Author) [es
Antideuteron annihilation on nuclei
International Nuclear Information System (INIS)
Cugnon, J.
1992-01-01
An investigation of antideuteron annihilation on nuclei within an intranuclear cascade (INC) model is presented. Two models are set up to describe the annihilation itself, which either implies the antideuteron as a whole and occurs at a single point, or which may be considered as two independent nucleon-antinucleon annihilation occurring at different points and different times. Particular attention is paid to the energy transferred from the pions issued from the annihilation to the nuclear system and to the possibility of having a multifragmentation of the target. The latter feature is investigated within a percolation model. The pion distribution and the energy distribution are also discussed. Predictions of proton multiplicity distributions are compared with experiment. (orig.)
International Nuclear Information System (INIS)
2002-01-01
The present collection of letters from JINR, Dubna, contains ten separate records on Wien filter using in exploring on low-energy radioactive nuclei, memory effects in dissipative nucleus-nucleus collision, topological charge and topological susceptibility in connection with translation and gauge invariance, solutions of the multitime Dirac equation, the maximum entropy technique. System's statistical description, the charged conductor inside dielectric. Solution of boundary condition by means of auxiliary charges and the method of linear algebraic equations, optical constants of the TGS single crystal irradiated by power pulsed electron beam, interatomic pair potential and n-e amplitude from slow neutron scattering by noble gases, the two-coordinate multiwire proportional chamber of the high spatial resolution and neutron drip line in the region of O-Mg isotopes
International Nuclear Information System (INIS)
2000-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on the integral representation for structure functions and target mass effects, multiscale properties of DNA primary structure including cross-scale correlations, dissipative evolution of the elementary act, the fine structure of the M T =1 Gamow-Teller resonance in 147g Tb→ 147 Gd β + /EC decay, the behaviour of the TVO temperature sensors in the magnetic fields, a fast method for searching for tracks in multilayer drift chambers of HADES spectrometer, a novel approach to particle track etching including surfactant enhanced control of pore morphology, azimuthal correlations of secondary particles in 32 S induced interactions with Ag(Br) nuclei at 4.5 GeV/ c/ nucleon
International Nuclear Information System (INIS)
Xu, Renxin
2011-01-01
What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the gigantic nucleus speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction. (author)
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This third volume follows the successful Lect. Notes Phys. 818 (Vol. 1) and 848 (Vol. 2), and comprises six extensive lectures covering the following topics: - Gamma Rays and Molecular Structure - Faddeev Equation Approach for Three Cluster Nuclear Reactions - Tomography of the Cluster Structure of Light Nuclei Via Relativistic Dissociation - Clustering Effects Within the Dinuclear Model : From Light to Hyper-heavy Molecules in Dynamical Mean-field Approach - Clusterization in Ternary Fission - Clusters in Light N...
International Nuclear Information System (INIS)
Afnan, I.R.; Thomas, A.W.
1976-01-01
A method has been suggested for relating μ-capture in nuclei to pion absorption through partially conserved axial vector current hypothesis. The success of the method relies heavily on the knowledge of the pion absorption amplitude at a momentum transfer equal to the μ-meson mass. That is we need to know the pion absorption amplitude off the mass-shell. The simplest nucleus for which this suggestion can be examined is μ-capture in deuterium. The Koltum-Reitan model is used to determine the pion absorption amplitude off the mass shell. In particular the senstivity of this off-mass-shell extrapolution to details of the N-N interaction is studied. (author)
International Nuclear Information System (INIS)
Casten, R.F.; Warner, D.D.
1982-01-01
The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for 168 Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong β → γ transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the β → γ transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ΔK=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics
Spectroscopy of heavy fissionable nuclei
Indian Academy of Sciences (India)
2015-08-05
Aug 5, 2015 ... Nuclei in the actinide chain and beyond are prone to fission owing to ... mass nuclei are typically more difficult, because the intensity is .... j15/2 neutron alignments in a region where shell stablization effects are crucial.
Lee, T. D.
1970-07-01
While the phenomenon of beta-decay was discovered near the end of the last century, the notion that the weak interaction forms a separate field of physical forces evolved rather gradually. This became clear only after the experimental discoveries of other weak reactions such as muon-decay, muon-capture, etc., and the theoretical observation that all these reactions can be described by approximately the same coupling constant, thus giving rise to the notion of a universal weak interaction. Only then did one slowly recognize that the weak interaction force forms an independent field, perhaps on the same footing as the gravitational force, the electromagnetic force, and the strong nuclear and sub-nuclear forces.
International Nuclear Information System (INIS)
Anon.
1979-01-01
The possibility of the production of weak bosons in the proton-antiproton colliding beam facilities which are currently being developed, is discussed. The production, decay and predicted properties of these particles are described. (W.D.L.).
International Nuclear Information System (INIS)
Turlay, R.
1979-01-01
In this review of charged weak currents I shall concentrate on inclusive high energy neutrino physics. There are surely still things to learn from the low energy weak interaction but I will not discuss it here. Furthermore B. Tallini will discuss the hadronic final state of neutrino interactions. Since the Tokyo conference a few experimental results have appeared on charged current interaction, I will present them and will also comment on important topics which have been published during the last past year. (orig.)
International Nuclear Information System (INIS)
Daumenov, T.D.; Alizarovskaya, I.M.; Khizirova, M.A.
2001-01-01
The method of the weakly oval electrical field getting generated by the axially-symmetrical field is shown. Such system may be designed with help of the cylindric form coaxial electrodes with the built-in quadrupole duplet. The singularity of the indicated weakly oval lense consists of that it provides the conducting both mechanical and electronic adjustment. Such lense can be useful for elimination of the near-axis astigmatism in the electron-optical system
Present and Future Experiments with Stored Exotic Nuclei at GSI
International Nuclear Information System (INIS)
Geissel, H.
2009-01-01
Recent results and perspectives of experiments with stored exotic nuclei at GSI-FAIR will presented. An overview on the planned NUSTAR experiments will also presented. Relativistic exotic nuclei produced via projectile fragmentation and fission were separated in flight by the fragment separator FRS and injected into the storage-cooler ring ESR for accurate mass- and lifetime measurements. Direct mass measurements of electron-cooled exotic nuclei were performed using time-resolved Schottky spectrometry. Fragments with half-lives shorter than the time required for electron cooling have been investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique gives access to all nuclei with half-lives down to the microsecond range and has been successfully applied. Lifetimes of stored bare and few-electron ions have been measured with the goal to study the beta-decay under ionization conditions prevailing in stellar plasma. For the first time the direct observation of bound-state beta decay has been achieved with 2 07T l fragments. The future project FAIR includes a new large-acceptance in-flight separator (Super-FRS) in combination with a new storage ring system (CR, NESR) which will be ideal tools to study exotic nuclei far from stability.(author)
Problem of ''deformed'' superheavy nuclei
International Nuclear Information System (INIS)
Sobiczewski, A.; Patyk, Z.; Muntian, I.
2000-08-01
Problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighbourhood of 270 Hs is discussed. Measurement of the energy E 2+ of the lowest 2+ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. The branching ratio p 2+ /p 0+ between α decay of a nucleus to this lowest 2+ state and to the ground state 0+ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy E 2+ for some superheavy nuclei by electron or α spectroscopy is a promising method for the confirmation of their deformed shapes. (orig.)
Directory of Open Access Journals (Sweden)
Holt Roy J.
2016-01-01
Full Text Available Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.
International Nuclear Information System (INIS)
Henley, E.M.
1981-09-01
Internal and space-time symmetries are discussed in this group of lectures. The first of the lectures deals with an internal symmetry, or rather two related symmetries called charge independence and charge symmetry. The next two discuss space-time symmetries which also hold approximately, but are broken only by the weak forces; that is, these symmetries hold for both the hadronic and electromagnetic forces
A quark structure of hadrons and nuclei
International Nuclear Information System (INIS)
Chakrabarty, S.; Deoghuria, S.
1992-08-01
In this review we look into the recent understanding of mesons, baryons and nuclei as few quark bound states within the framework of quantum chromodynamics (QCD). In particular, we have reviewed our understanding of the nature of confining interaction, the spin - dependence of colour forces and the role of non-perturbative effects in the study of quark forces in the potential model approach. We also give a comparative study of results obtained by several potential models with reference to the experimental data. We find that although the Lorentz nature of confinement and the nature of spin-dependent colour forces have been better understood now, only a partial understanding of these problems are obtained so far. Our study reveals that properties of baryons could be explained by the same potential model which successfully describe the mesons. However, the nuclei require chiral symmetry and non-perturbative methods for their description. We also discuss the relation between constituent, current and dynamical quark masses. We conclude that QCD motivated approaches have shown much success in explaining many results on hadronic and nuclear data. (author). 212 refs, 14 tabs
Photoproduction of Mesons off Light Nuclei
International Nuclear Information System (INIS)
Keshelashvili, Irakli
2011-01-01
During the last few years, a series of experiments has been done at the ELSA accelerator in Bonn with the Crystal Barrel/TAPS setup and at the MAMI accelerator in Mainz with the Crystal Ball/TAPS setup. Photoproduction of light mesons off the deuteron and 3 He-nuclei has been studied in detail. We will report some of the most interesting results.A completely unexpected finding, is the pronounced structure in the excitation function of the γn → nη reaction around 1 GeV, which has no counterpart for the proton. Recent measurements at GRAAL, Sendai, ELSA [1] and MAMI estimate it's width below 50 MeV, which would be extremely narrow for a nucleon resonance at this excitation energy. In the experiment with the 3 He target, special attention was given to the threshold behavior of the γHe 3 reactions in view of possible indications for the formation of (quasi-)bound η-nucleus states, so-called η-mesic nuclei. A very strong threshold enhancement of coherent η-photoproduction off 3 He was found. In a new experiment, this reaction was measured with much better statistical accuracy compared to an earlier experiment at MAMI-B using the TAPS detector [2].
DEFF Research Database (Denmark)
Damgård, Ivan Bjerre; Faust, Sebastian; Mukherjee, Pratyay
2013-01-01
Related key attacks (RKAs) are powerful cryptanalytic attacks where an adversary can change the secret key and observe the effect of such changes at the output. The state of the art in RKA security protects against an a-priori unbounded number of certain algebraic induced key relations, e.......g., affine functions or polynomials of bounded degree. In this work, we show that it is possible to go beyond the algebraic barrier and achieve security against arbitrary key relations, by restricting the number of tampering queries the adversary is allowed to ask for. The latter restriction is necessary......-protocols (including the Okamoto scheme, for instance) are secure even if the adversary can arbitrarily tamper with the prover’s state a bounded number of times and obtain some bounded amount of leakage. Interestingly, for the Okamoto scheme we can allow also independent tampering with the public parameters. We show...
Massive Galileon positivity bounds
de Rham, Claudia; Melville, Scott; Tolley, Andrew J.; Zhou, Shuang-Yong
2017-09-01
The EFT coefficients in any gapped, scalar, Lorentz invariant field theory must satisfy positivity requirements if there is to exist a local, analytic Wilsonian UV completion. We apply these bounds to the tree level scattering amplitudes for a massive Galileon. The addition of a mass term, which does not spoil the non-renormalization theorem of the Galileon and preserves the Galileon symmetry at loop level, is necessary to satisfy the lowest order positivity bound. We further show that a careful choice of successively higher derivative corrections are necessary to satisfy the higher order positivity bounds. There is then no obstruction to a local UV completion from considerations of tree level 2-to-2 scattering alone. To demonstrate this we give an explicit example of such a UV completion.
Resonances in A=6 nuclei: use of supersymmetric quantum mechanics
International Nuclear Information System (INIS)
Dutta, S.K.; Das, T.K.; Khan, M.A.; Chakrabarti, B.
2004-01-01
We propose a novel theoretical technique for the calculation of resonances at low excitation energies in weakly bound systems. Starting from an effective potential, supersymmetric quantum mechanics can be successfully used to generate families of isospectral potentials having desirable and adjustable properties. For resonance states, for which there is no bound ground state of the same spin-parity, one can construct an isospectral potential with a bound state in the continuum (BIC). The potential looks quite different but is strictly isospectral with the original one. The quasi-bound state in the original shallow potential will be effectively trapped in the deep well of the isospectral family facilitating an easier and more accurate calculation of the resonance energy. Application to 6 He, 6 Be, and 6 Li systems yields quite accurate results. The beauty of our technique: We get both the bound ground state and the resonances by a single technique and using the same potential. (author)
Effects of deformations and orientations on neutron-halo structure of light-halo nuclei
International Nuclear Information System (INIS)
Sawhney, Gudveen; Gupta, Raj K.; Sharma, Manoj K.
2013-01-01
The availability of radioactive nuclear beams have enabled to study the structure of nuclei far from the stability line, which in turn led to the discovery of neutron-halo nuclei. These nuclei, located near the neutron drip-line exhibit a high probability of presence of one or two loosely bound neutrons at a large distance from the rest of nucleons. The fragmentation behavior is studied for 13 cases of 1n-halo nuclei, which include 11 Be, 14 B, 15 C, 17 C, 19 C, 22 N, 22 O, 23 O, 24 O, 24 F, 26 F, 29 Ne and 31 Ne, using the cluster-core model (CCM) extended to include the deformations and orientations of nuclei
Muon capture by the 1p shell of 10B, 12C and 14N nuclei. Experiments and interpretation
International Nuclear Information System (INIS)
Moura Goncalves, A.C. de.
1980-12-01
The main elements necessary to treat weak interactions in a nucleus including the contributions of exchange meson currents are presented. The case of a transition between an initial (Z,A) nucleus and a final (Z-1,A) nucleus in a well defined bound state is treated. The form of the single body operator taking into account the nucleonic degrees of freedom (impulse approximation) is recalled. The construction of a two-body operator taking mesonic degrees of freedom into account is outlined. Measurements of partial capture rates in 10 B, 12 C and 14 N target nuclei leading to excited bound states of 10 Be, 12 B and 14 C residual nuclei are described. Results are given and comparisons made with the calculations performed, nuclear states being described by various wave functions. Measurements of the polarization of the 1 + ground state of 12 B after N capture in 12 C are briefly described. An attempt is made to interpret the 0 + 1 + transition occurring in the A = 12 triad. A convenient parametrization is obtained from the expression for these observable quantities as a function of the nuclear shape factors. This analysis enables a strict choice to be made from the available wavefunctions. It demonstrates that experimental data are well reproduced by the microscopy approach performed using the effective Sussex potential and single pion exchange currents. Finally, the hitherto unexplored domain of muon capture is tackled. A high energy transfer is involved in which the neutrino remains practically at rest. In this case, the vector part is not very important and the axial current time part contributes as much is the space part. The (μ - ,pn) reaction was used for exploratory measurements in this domain. Practical limits are determined [fr
Brodeur, M.; Brunner, T.; Ettenauer, S.; Lapierre, A.; Ringle, R.; Delheij, P.; Dilling, J.
2009-05-01
Exotic nuclei are characterized with an extremely unbalanced protons-neutrons ratio (p/n) where for instance, the halo isotopes of He and Li have up to 3X more n than p (compared to p/n = 1 in ^12C). The properties of these exotic halo nuclei have long been recognized as the most stringent tests of our understanding of the strong force. ^11Li belongs to a special category of halos called Borromean, bound as a three-body family, while the two-body siblings, ^10Li and 2 n, are unbound as separate entities. Last year, a first mass measurement of the radioisotope ^11Li using a Penning trap spectrometer was carried out at the TITAN (Triumf's Ion Trap for Atomic and Nuclear science) facility at TRIUMF-ISAC. Penning traps are proven to be the most precise device to make mass measurements, yet until now they were unable to reach these nuclei. At TRIUMF we managed to measure the mass of ^11Li to an unprecedented precision of dm/m = 60 ppb, which is remarkable since it has a half-life of only 8.8 ms which it the shortest-lived nuclide to be measured with this technique. Furthermore, new and improved masses for the 2 and 4 n halo ^6,8He, as well has the 1 n halo ^11Be have been performed. An overview of the TITAN mass measurement program and its impact in understanding the most exotic nuclei will be given.
Search for quasi bound η mesons
International Nuclear Information System (INIS)
Machner, H
2015-01-01
The search for a quasi bound η meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally. The theory starts from elastic η nucleon scattering which is derived from production data within some models. From this interaction the η nucleus interaction is derived. Model calculations predict binding energies and widths of the quasi bound state. Another method is to derive the η nucleus interaction from excitation functions of η production experiments. The s wave interaction is extracted from such data via final state interaction (FSI) theorem. We give the derivation of s wave amplitudes in partial wave expansion and in helicity amplitudes and their relation to observables. Different experiments extracting the FSI are discussed as are production experiments. So far only three experiments give evidence for the existence of the quasi bound state: a pion double charge exchange experiment, an effective mass measurement, and a transfer reaction at recoil free kinematics with observation of the decay of the state. (topical review)
Covalently bound molecular states in beryllium and carbon isotopes
International Nuclear Information System (INIS)
Wolfram von, Oertzen; Hans-Gerhard, Bohlen; Wolfram von, Oertzen
2003-01-01
Nuclear clustering in N=Z nuclei has been studied since many decades. States close to the decay thresholds, as described by the Ikeda diagram, are of particular interest. Recent studies in loosely bound systems, as observed with neutron-rich nuclei has revived the interest in cluster structures in nuclei, with additional valence neutrons, which give rise to pronounced covalent molecular structures. The Beryllium isotopes represent the first example of such unique states in nuclear physics with extreme deformations. In the deformed shell model these are referred to as super- and hyper-deformation. These states can be described explicitly by molecular concepts, with neutrons in covalent binding orbits. Examples of recent experiments performed at the HMI-Berlin demonstrating the molecular structure of the rotational bands in Beryllium isotopes are presented. Further work on chain states (nuclear polymers) in the carbon isotopes is in progress, these are the first examples of deformed structures in nuclei with an axis ratio of 3:1. A threshold diagram with clusters bound via neutrons in covalent molecular configurations can be established, which can serve as a guideline for future work. (authors)
Neutron emission study after muon capture by nuclei
International Nuclear Information System (INIS)
Bouyssy, Alain.
1974-01-01
Muon capture by nuclei, used in the beginning for checking the weak interaction, is now a method of investigation of nuclear structure. Study of spectrum, asymmetry and polarization of emitted neutrons after polarized muon capture has been done in three directions: weak coupling constants, final state interaction, nuclear wave functions. The neutron intensity and helicity are very dependent of the neutron - residual nucleus interaction, while the asymmetry is sensitive to the wave functions used for the proton. Moreover if the induced tensor coupling constant is different from zero the asymmetry is increased. Longitudinal polarization experiments, with those for neutron intensity, would be of great interest to give informations on neutron asymmetry [fr
Appell, Jürgen; Merentes Díaz, Nelson José
2013-01-01
This monographis a self-contained exposition of the definition and properties of functionsof bounded variation and their various generalizations; the analytical properties of nonlinear composition operators in spaces of such functions; applications to Fourier analysis, nonlinear integral equations, and boundary value problems. The book is written for non-specialists. Every chapter closes with a list of exercises and open problems.
International Nuclear Information System (INIS)
Lima, V.
2004-10-01
In a towing mode reaction the projectile picks up a nucleon from the target and then breaks up by emitting one nucleon. The velocity of the emitted nucleon is boosted by the projectile velocity, leading to the emission of the nucleon in a narrow cone around the direction of the scattered projectile. This work is dedicated to the towing mode in halo nuclei such as Be 11 . The experiment was performed at Ganil facility by bombarding a Ti 48 target with a 41 MeV per nucleon Be 11 beam, the reaction studied is: Ti 48 (Be 11 , Be 10 + n + γ). The first chapter reviews the various nuclear processes that take place when 2 nuclei collide with a particular attention for the towing mode. The second chapter is dedicated to solving the time dependant Schroedinger equation (TDSE) in order to assess the impact of various parameters such as incident energy, target charge or the linking energy of the nucleon, on the towing mode reaction. The third chapter deals with the experimental equipment and set-up including detectors and the data acquisition system. Computerized simulations have been performed in order to assess the efficiency of the detecting system, they are presented in the fourth chapter. A comparison between experimental data and the results from TDSE solving, concerning the energy spectra of the emitted particles, has enabled the author to deduce the spectroscopic factors for the different contributions of the fundamental state of Be 11 , they are presented in the last chapter. The cross-sections of the towing mode are of the magnitude of several tens of milli-barns in the case of weakly bound nuclei like Be 11 which make it an efficient tool to study intern structure of nuclei. (A.C.)
Monopole transitions in hot nuclei
International Nuclear Information System (INIS)
Sujkowski, Z.
1994-01-01
Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs
Monopole transitions in hot nuclei
Energy Technology Data Exchange (ETDEWEB)
Sujkowski, Z. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)
1994-12-31
Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs.
Electron scattering for exotic nuclei
International Nuclear Information System (INIS)
Suda, T.
2013-01-01
An electron scattering facility is under construction in RIKEN RI Beam Factory, Japan, which is dedicated to the structure studies of short-lived nuclei. This is the world's first and currently only facility of its type. The construction is nearly completed, and the first electron scattering experiment off short-lived nuclei will be carried out in the beginning of next year. The charge density distributions of short-lived nuclei will be precisely determined by elastic electron scattering for the first time. Physics pursued at this facility including future perspectives are explained
International Nuclear Information System (INIS)
Ayala, A.L.
1996-01-01
In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab
Jolie, J
2002-01-01
All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He sup 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold sup 1 sup 9 sup 5 sup - sup 1 sup 9 sup 6 and Platinum sup 1 sup 9 sup 4 - sup 1 sup 9 sup 5 , it means that the description of these energy levels is simplified and can be made by a co...
International Nuclear Information System (INIS)
Jolie, J.
2002-01-01
All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold 195-196 and Platinum 194 - 195 , it means that the description of these energy levels is simplified and can be made by a common set of quantum numbers. (A.C.)
Photon interactions with nuclei
International Nuclear Information System (INIS)
Thornton, S.T.; Sealock, R.M.
1989-01-01
This document is a progress report for DOE Grant No. FG05-89ER40501, A000. The grant began March, 1989. Our primary research effort has been expended at the LEGS project at Brookhaven National Laboratory. This report will summarize our present research effort at LEGS as well as data analysis and publications from previous experiments performed at SLAC. In addition the principal investigators are heavily involved in the CLAS collaboration in Hall B at CEBAF. We have submitted several letters of intent and proposals and have made commitments to construct experimental equipment for CEBAF. We expect our primary experimental effort to continue at LEGS until CEBAF becomes operational. This report will be divided into separate sections describing our progress at LEGS, SLAC, and CEBAF. We will also discuss our significant efforts in the education and training of both undergraduate and graduate students. Photon detectors are described as well as experiments on delta deformation in nuclei of quasielastic scattering and excitation of the delta by 4 He(e,e')
Fragmentation of relativistic nuclei
International Nuclear Information System (INIS)
Cork, B.
1975-06-01
Nuclei with energies of several GeV/n interact with hadrons and produce fragments that encompass the fields of nuclear physics, meson physics, and particle physics. Experimental results are now available to explore problems in nuclear physics such as the validity of the shell model to explain the momentum distribution of fragments, the contribution of giant dipole resonances to fragment production cross sections, the effective Coulomb barrier, and nuclear temperatures. A new approach to meson physics is possible by exploring the nucleon charge-exchange process. Particle physics problems are explored by measuring the energy and target dependence of isotope production cross sections, thus determining if limiting fragmentation and target factorization are valid, and measuring total cross sections to determine if the factorization relation, sigma/sub AB/ 2 = sigma/sub AA/ . sigma/sub BB/, is violated. Also, new experiments have been done to measure the angular distribution of fragments that could be explained as nuclear shock waves, and to explore for ultradense matter produced by very heavy ions incident on heavy atoms. (12 figures, 2 tables)
International Nuclear Information System (INIS)
Arima, A.
2003-01-01
(1) There are symmetries in nature, and the concept of symmetry has been used in art and architecture. The symmetry is evaluated high in the European culture. In China, the symmetry is broken in the paintings but it is valued in the architecture. In Japan, however, the symmetry has been broken everywhere. The serious and interesting question is why these differences happens? (2) In this lecture, I reviewed from the very beginning the importance of the rotational symmetry in quantum mechanics. I am sorry to be too fundamental for specialists of nuclear physics. But for people who do not use these theories, I think that you could understand the mathematical aspects of quantum mechanics and the relation between the angular momentum and the rotational symmetry. (3) To the specialists of nuclear physics, I talked about my idea as follows: dynamical treatment of collective motions in nuclei by IBM, especially the meaning of the degeneracy observed in the rotation bands top of γ vibration and β vibration, and the origin of pseudo-spin symmetry. Namely, if there is a symmetry, a degeneracy occurs. Conversely, if there is a degeneracy, there must be a symmetry. I discussed some details of the observed evidence and this correspondence is my strong belief in physics. (author)
International Nuclear Information System (INIS)
Roberts, B.L.; Booth, E.C.; Gall, K.P.; McIntyre, E.K.; Miller, J.P.; Whitehouse, D.A.; Bassalleck, B.; Hall, J.R.; Larson, K.D.; Wolfe, D.M.; Fickinger, W.J.; Robinson, D.K.; Hallin, A.L.; Hasinoff, M.D.; Measday, D.F.; Noble, A.J.; Waltham, C.E.; Hessey, N.P.; Lowe, J.; Horvath, D.; Salomon, M.
1990-01-01
New measurements of the Σ + and Λ weak radiative decays are discussed. The hyperons were produced at rest by the reaction K - p → Yπ where Y = Σ + or Λ. The monoenergetic pion was used to tag the hyperon production, and the branching ratios were determined from the relative amplitudes of Σ + → pγ to Σ + → pπ 0 and Λ → nγ to Λ → nπ 0 . The photons from weak radiative decays and from π 0 decays were detected with modular NaI arrays. (orig.)
Heavy quarkonium production and propagation in nuclei
International Nuclear Information System (INIS)
Wong, C.Y.
1997-01-01
In the search for the quark-gluon plasma, it has been suggested that the production of charmonium will be suppressed in a quark-gluon plasma because of the screening of the interaction between c and anti c. To extract information on the suppression due to the quark-gluon plasma, it is necessary to study the suppression of J/ψ production by sources different from the quark-gluon plasma. It is therefore useful to examine the mechanism of heavy quarkonium production and its propagation in nuclei. The authors describe a precursor in heavy quarkonium production in terms of a coherent admixture of states of different color, spin, and angular momentum quantum numbers, and obtain the production amplitudes for different quarkonium bound states by projecting out this precursor state onto these bound states. The precursor is absorbed in its passage through a nucleus in a pA reaction, and the total cross section between this precursor with a nucleon can be calculated with the two-gluon model of the Pomeron. Such a description of coherent precursors and their subsequent interactions with nucleons can explain many salient features of J/ψ and ψ' production in pA collisions
γ transitions from 30P and 32S nuclei resonance levels
International Nuclear Information System (INIS)
Kostin, V.Ya.; Kopanets, E.G.; Koval', A.A.
1977-01-01
The probability distributions of dipole and quadrupole electromagnetic transitions from resonance excitation-energy range from 6.2 to 8.3 MeV and from 9.2 to 12.0 MeV respectively, were obtained. An analysis of the distributions shows that isovector dipole electic and magnetic transitions are comparable in magnitude with transitions between bound states. Isoscalar dipole transitions are stronger by an order of magnitude than transitions between bound states. This may be attributed to the increase in isospin mixing in the resonance range of excitation of atomic nuclei. Quadrupole electrical transitions have strengths comparable with those of transitions between bound states. For magnetic quadrupole transitions, a strong increase in transition probabilities compared with transitions between bound states is noted. The isospin selection rules for γ transitions in self-conjugate nuclei are discussed
Dynamic polarization of radioactive nuclei
International Nuclear Information System (INIS)
Kiselev, Yu.F.; Lyuboshits, V.L.; )
2001-01-01
Radioactive nuclei, embedded into a frozen polarized proton target, atr proposed to polarize by means of some dynamic polarization methods. Angular distributions of γ-quanta emitted ny 22 Na(3 + ) in the cascade β-γ-radiation are calculated. It is shown that this distribution does not depend on the spin temperature sing at the Boltzmann distribution of populations among the Zeeman magnetic substates, whereas the tensor polarization of quadrupole nuclei, placed in the electric field of the crystal, causes the considerable sing dependence. The new method promises wide opportunities for the magnetic structure investigations as well as for the study of spin-spin interaction dynamics of rare nuclei in dielectrics. Physical-technical advantages and disadvantages of the given method are discussed for the polarization of heavy nuclei in the on-line implantation mode [ru
The delta in nuclei. Experiments
International Nuclear Information System (INIS)
Roy-Stephan, M.
1989-01-01
Experimental aspects of the Δ excitation will be presented. The Δ excitation in nuclei will be compared to the free Δ excitation. Various probes will be reviewed and their specific features will be underlined [fr
Electron scattering for exotic nuclei
Indian Academy of Sciences (India)
2014-11-04
Nov 4, 2014 ... Research Center for Electron-Photon Science, Tohoku University, 1-2-1 ... nuclei precisely determined by elastic scattering [1]. .... In order to fulfill these requirements, a window-frame shaped dipole magnet with a gap.
Towards a quantitative description of hadronic weak decays
International Nuclear Information System (INIS)
Bigi, I.I.Y.
1981-01-01
We develop a formalism for describing hadronic weak annihilation decays in analogy to the treatment of deep inelastic lepton-nucleon scattering: we write down evolution equations for colour singlet and octet (Qanti q) systems inside mesons of increasing mass. Using D decays as input we can predict weak annihilation decay rates of heavier mesons in a semiquantitative fashion despite our ignorance on bound-state dynamics. (orig.)
Startpoints via weak contractions
Agyingi, Collins Amburo; Gaba, Yaé Ulrich
2018-01-01
Startpoints (resp. endpoints) can be defined as "oriented fixed points". They arise naturally in the study of fixed for multi-valued maps defined on quasi-metric spaces. In this article, we give a new result in the startpoint theory for quasi-pseudometric spaces. The result we present is obtained via a generalized weakly contractive set-valued map.
Hadi, Inaam M. A.; Al-aeashi, Shukur N.
2018-05-01
If R is a ring with identity and M is a unitary right R-module. Here we introduce the class of weakly coretractable module. Some basic properties are investigated and some relationships between these modules and other related one are introduced.
Collisions between complex atomic nuclei
International Nuclear Information System (INIS)
Vaagen, J. S.
1977-08-01
The use of heavy ion accelerators in the study of nuclear structure and states is reviewed. The reactions discussed are the quasielastic reactions in which small amounts of energy and few particles are exchanged between the colliding nuclei. The development of heavy ion accelerators is also discussed, as well as detection equipment. Exotic phenomena, principally the possible existence of superheavy nuclei, are also treated. (JIW)
Energy Technology Data Exchange (ETDEWEB)
Anon.
1987-07-15
PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa.
International Nuclear Information System (INIS)
Anon.
1987-01-01
PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa
Investigation of copper nuclei
International Nuclear Information System (INIS)
Delfini, M.G.
1983-01-01
An extensive study has been performed on copper isotopes in the mass region A=63-66. The results of a precise measurement are presented on the properties of levels of 64 Cu and 66 Cu. They were obtained by bombarding the 63 Cu and 65 Cu nuclei with neutrons. The gamma spectra collected after capture of thermal, 2-keV, 24-keV neutrons have been analysed and combined to give a rather extensive set of precise level energies and gamma transition strengths. From the angular distribution of the gamma rays it is possible to obtain information concerning the angular momentum J of several low-lying states. The level schemes derived from such measurements have been used as a test for calculations in the framework of the shell model. The spectral distributions of eigenstates in 64 Cu for different configuration spaces are presented and discussed. In this study the relative importance of configurations with n holes in the 1f7/2 shell with n up to 16, are investigated. It is found that the results strongly depend on the values of the single-particle energies. The results of the spectral-distribution method were utilized for shell-model calculations. From the information obtained from the spectral analysis it was decided to adopt a configuration space which includes up to one hole in the 1f7/2 shell and up to two particles in the 1g9/2 shell. Further, restrictions on seniority and on the coupling of the two particles in the 1g9/2 orbit have been applied and their effects have been studied. It is found that the calculated excitation energies reproduce the measured values in a satisfactory way, but that some of the electromagnetic properties are less well in agreement with experimental data. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Heenen, P.H. [Universite Libre de Bruxelles, Service de Physique Nucleaire Theorique (Belgium); Nazarewicz, W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Physics; Warsaw Univ. (Poland). Inst. Fizyki Teoretycznej
2002-02-01
This article draws the long history of the discovery of new heavy nuclei since its beginning in 1940 when neptunium was found, and presents the current status of research in this field. The last 3 years have brought a number of experimental surprises which have truly rejuvenated the field. In January 1999, scientists from Dubna (Russia) reported the synthesis of 1 atom of element 114 ({sup 298}Uuq) in a hot fusion reaction between a {sup 48}Ca beam and a {sup 244}Pu target. This discovery was followed by 3 other reports from Dubna. First using the {sup 242}Pu({sup 48}Ca,3n) reaction, they produced {sup 287}Uuq. In 1999 the synthesis of another isotope of Z=114, the even-even {sup 288}Uuq was reported. The element Z=116 ({sup 292}Uuh) was discovered as a product of the {sup 248}Cm({sup 48}Ca,4n) reaction. The GSI (Germany) group found a new even isotope of the element 110: {sup 270}Uun and also {sup 272}Uuu (element 111) and {sup 277}Uub (element 112). 2 new isotopes of the element 107: {sup 266}Bh and {sup 267}Bh have been found at Berkeley (Usa). The synthesis of the new element Z=118 ({sup 293}Uuo) announced in 1999 by the Berkeley group was retracted 2 years later. The lifetimes reported for the elements {sup 284}Uub and {sup 280}Uun are by many orders of magnitude longer than those of the isotopes with Z{<=}112 previously discovered at GSI. (A.C.)
Kahneman, Daniel
2002-01-01
The work cited by the Nobel committee was done jointly with the late Amos Tversky (1937-1996) during a long and unusually close collaboration. Together, we explored the psychology of intuitive beliefs and choices and examined their bounded rationality. This essay presents a current perspective on the three major topics of our joint work: heuristics of judgment, risky choice, and framing effects. In all three domains we studied intuitions - thoughts and preferences that come to mind quickly an...
Bounded Satisfiability for PCTL
Bertrand, Nathalie; Fearnley, John; Schewe, Sven
2012-01-01
While model checking PCTL for Markov chains is decidable in polynomial-time, the decidability of PCTL satisfiability, as well as its finite model property, are long standing open problems. While general satisfiability is an intriguing challenge from a purely theoretical point of view, we argue that general solutions would not be of interest to practitioners: such solutions could be too big to be implementable or even infinite. Inspired by bounded synthesis techniques, we turn to the more appl...
Spectrin-like proteins in plant nuclei
Ruijter, de N.C.A.; Ketelaar, T.; Blumenthal, S.S.D.; Emons, A.M.C.; Schel, J.H.N.
2000-01-01
We analysed the presence and localization of spectrin-like proteins in nuclei of various plant tissues, using several anti-erythrocyte spectrin antibodies on isolated pea nuclei and nuclei in cells. Western blots of extracted purified pea nuclei show a cross-reactive pair of bands at 220–240 kDa,
Introduction to weak interactions
International Nuclear Information System (INIS)
Leite Lopes, J.
An account is first given of the electromagnetic interactions of complex, scalar, vector and spinor fields. It is shown that the electromagnetic field may be considered as a gauge field. Yang-Mills fields and the field theory invariant with respect to the non-Abelian gauge transformation group are then described. The construction, owing to this invariance principle, of conserved isospin currents associated with gauge fields is also demonstrated. This is followed by a historical survey of the development of the weak interaction theory, established at first to describe beta disintegration processes by analogy with electrodynamics. The various stages are mentioned from the discovery of principles and rules and violation of principles, such as those of invariance with respect to spatial reflection and charge conjugation to the formulation of the effective current-current Lagrangian and research on the structure of weak currents [fr
Asymptotic theory of weakly dependent random processes
Rio, Emmanuel
2017-01-01
Presenting tools to aid understanding of asymptotic theory and weakly dependent processes, this book is devoted to inequalities and limit theorems for sequences of random variables that are strongly mixing in the sense of Rosenblatt, or absolutely regular. The first chapter introduces covariance inequalities under strong mixing or absolute regularity. These covariance inequalities are applied in Chapters 2, 3 and 4 to moment inequalities, rates of convergence in the strong law, and central limit theorems. Chapter 5 concerns coupling. In Chapter 6 new deviation inequalities and new moment inequalities for partial sums via the coupling lemmas of Chapter 5 are derived and applied to the bounded law of the iterated logarithm. Chapters 7 and 8 deal with the theory of empirical processes under weak dependence. Lastly, Chapter 9 describes links between ergodicity, return times and rates of mixing in the case of irreducible Markov chains. Each chapter ends with a set of exercises. The book is an updated and extended ...
Rakipi, Albert
2006-01-01
Cataloged from PDF version of article. Although the weak 1 failing states have often been deseribed as the single most important problem for the international order s ince the en d of Cold W ar (F .Fukuyaına 2004:92) several dimensions of this phenomenon still remain unexplored. While this phenomenon has been present in the international politics even earlier, only the post Cold W ar period accentuated its relationship with security issues. Following the Cold W ar' s "peacef...
Energy Technology Data Exchange (ETDEWEB)
Suzuki, M.
1988-04-01
Dynamical mechanism of composite W and Z is studied in a 1/N field theory model with four-fermion interactions in which global weak SU(2) symmetry is broken explicitly by electromagnetic interaction. Issues involved in such a model are discussed in detail. Deviation from gauge coupling due to compositeness and higher order loop corrections are examined to show that this class of models are consistent not only theoretically but also experimentally.
Universal bounds on current fluctuations.
Pietzonka, Patrick; Barato, Andre C; Seifert, Udo
2016-05-01
For current fluctuations in nonequilibrium steady states of Markovian processes, we derive four different universal bounds valid beyond the Gaussian regime. Different variants of these bounds apply to either the entropy change or any individual current, e.g., the rate of substrate consumption in a chemical reaction or the electron current in an electronic device. The bounds vary with respect to their degree of universality and tightness. A universal parabolic bound on the generating function of an arbitrary current depends solely on the average entropy production. A second, stronger bound requires knowledge both of the thermodynamic forces that drive the system and of the topology of the network of states. These two bounds are conjectures based on extensive numerics. An exponential bound that depends only on the average entropy production and the average number of transitions per time is rigorously proved. This bound has no obvious relation to the parabolic bound but it is typically tighter further away from equilibrium. An asymptotic bound that depends on the specific transition rates and becomes tight for large fluctuations is also derived. This bound allows for the prediction of the asymptotic growth of the generating function. Even though our results are restricted to networks with a finite number of states, we show that the parabolic bound is also valid for three paradigmatic examples of driven diffusive systems for which the generating function can be calculated using the additivity principle. Our bounds provide a general class of constraints for nonequilibrium systems.
Nee, Sean
2018-05-01
Survival analysis in biology and reliability theory in engineering concern the dynamical functioning of bio/electro/mechanical units. Here we incorporate effects of chaotic dynamics into the classical theory. Dynamical systems theory now distinguishes strong and weak chaos. Strong chaos generates Type II survivorship curves entirely as a result of the internal operation of the system, without any age-independent, external, random forces of mortality. Weak chaos exhibits (a) intermittency and (b) Type III survivorship, defined as a decreasing per capita mortality rate: engineering explicitly defines this pattern of decreasing hazard as 'infant mortality'. Weak chaos generates two phenomena from the normal functioning of the same system. First, infant mortality- sensu engineering-without any external explanatory factors, such as manufacturing defects, which is followed by increased average longevity of survivors. Second, sudden failure of units during their normal period of operation, before the onset of age-dependent mortality arising from senescence. The relevance of these phenomena encompasses, for example: no-fault-found failure of electronic devices; high rates of human early spontaneous miscarriage/abortion; runaway pacemakers; sudden cardiac death in young adults; bipolar disorder; and epilepsy.
Hyperquarks and bosonic preon bound states
International Nuclear Information System (INIS)
Schmid, Michael L.; Buchmann, Alfons J.
2009-01-01
In a model in which leptons, quarks, and the recently introduced hyperquarks are built up from two fundamental spin-(1/2) preons, the standard model weak gauge bosons emerge as preon bound states. In addition, the model predicts a host of new composite gauge bosons, in particular, those responsible for hyperquark and proton decay. Their presence entails a left-right symmetric extension of the standard model weak interactions and a scheme for a partial and grand unification of nongravitational interactions based on, respectively, the effective gauge groups SU(6) P and SU(9) G . This leads to a prediction of the Weinberg angle at low energies in good agreement with experiment. Furthermore, using evolution equations for the effective coupling strengths, we calculate the partial and grand unification scales, the hyperquark mass scale, as well as the mass and decay rate of the lightest hyperhadron.
Test of Symmetries with Neutrons and Nuclei
International Nuclear Information System (INIS)
Paul, Stephan
2009-01-01
Precision experiments at low energies probing weak interaction are a very promising and complementary tool for investigating the structure of the electro-weak sector of the standard model, and for searching for new phenomena revealing signs for an underlaying new symmetry. With the advent of new technologies in particle trapping and production of beams for exotic nuclei as well as ultracold neutrons, we expect one or two orders of magnitude gain in precision. This corresponds to the progress expected by new high luminosity B-factories or the LHC. Domains studied are β-decays where decay correlations, partial or total decay rates may reveal the nature of the left-right structure of the interaction and the investigation of discrete symmetries. Here the search for a finite electric dipole moment which, due to its CP-violating nature were sensational by itself, could shed light on the structure of the vacuum at very small distances. Last but not least ideas of a mirror world can be extended to the sector of baryons which can be studied with neutrons.
From heavy nuclei to super-heavy nuclei
International Nuclear Information System (INIS)
Theisen, Ch.
2003-01-01
The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)
Complete destruction of heavy nuclei by hadrons and nuclei
International Nuclear Information System (INIS)
Tolstov, K.D.
1980-01-01
The total disintegration is considered of Ag and Pb nuclei and 4 He, 12 C nuclei With a momentum of 4.5 GeV/c per nucleon. It is shown that nucleons are mainly emitted, and there is no residual nUcleus the mass of which is comparable to that of the primary nucleus. The probability of total nucleus disintegration is considered as a function of projectile energy and the mass. The multiplicity, energy and emission angle of particles are considerred as well. It is shown that the density of nuclear matter in the overlap zone of colliding nuclei exceeds the usual one by a factor of approximately 4. A comparison is made with interaction models. A conclusion is drawn of the collective interaction mechanism (perhaps, of the shock wave type) of particle ejection from the target nucleus at the first stage of interaction and of explosive decay of the residual nucleus at the next one
The definite article in Romance expletives and long weak definites
Directory of Open Access Journals (Sweden)
M.Teresa Espinal
2017-03-01
Full Text Available This paper focuses on some issues involving expletive articles and long weak definites in Romance (mainly Spanish, Brazilian Portuguese and Catalan, in comparison to DPs that elicit a strong reading. We show the similarities between expletive definites and long weak definites, and we argue for an analysis in common to other polarity items in terms of polarity sensitivity. We reach the conclusion that the definite article in Romance comes in two variants: the referentially unique variant (to be translated as the semantic 'iota 'operator and the polar variant, formally characterized with an abstract [+σ] feature, that encodes a weak bound reading (to be semantically translated by an existential operator.
Tight Bell Inequalities and Nonlocality in Weak Measurement
Waegell, Mordecai
A general class of Bell inequalities is derived based on strict adherence to probabilistic entanglement correlations observed in nature. This derivation gives significantly tighter bounds on local hidden variable theories for the well-known Clauser-Horne-Shimony-Holt (CHSH) inequality, and also leads to new proofs of the Greenberger-Horne-Zeilinger (GHZ) theorem. This method is applied to weak measurements and reveals nonlocal correlations between the weak value and the post-selection, which rules out various classical models of weak measurement. Implications of these results are discussed. Fetzer-Franklin Fund of the John E. Fetzer Memorial Trust.
Energy Technology Data Exchange (ETDEWEB)
Canto, L F; Donangelo, R [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Hussein, M S [Sao Paulo Univ. (Brazil). Inst. de Fisica
1991-07-01
The eikonal theory of the dynamic polarization potential (DDP) is developed. Application to the scattering of loosely bound exotic nuclei is made. In particular, the effect of our DPP on the scattering of {sup 11}Li+{sup 12}C at 85 AxMeV is discussed. (orig.).
γ-ray spectroscopy of N=Z nuclei
International Nuclear Information System (INIS)
Lister, C. J.
1999-01-01
The use of γ-ray spectroscopy to probe the properties of marginally bound nuclear states has evolved from being a curiosity a decade ago to being the mainstream use for these devices. The key to this success has been the development of ultra-sensitive channel selection techniques which allow the parentage of each emitted γ-ray to be established. With these techniques, and the enhanced efficiency of the arrays themselves, the level of sensitivity for nuclear spectroscopy has increased by several orders of magnitude, in some special cases reaching the 10's nanobarns level, 1000 times more sensitive than was possible a decade ago. In this paper I will discuss some recent developments in light nuclear spectroscopy, on nuclei with N=Z, below mass 100. These examples have been chosen to compliment other presentations at this conference which have covered similar experiments in heavier nuclei
Energy Technology Data Exchange (ETDEWEB)
Maldacena, Juan [School of Natural Sciences, Institute for Advanced Study,1 Einstein Drive, Princeton, NJ (United States); Shenker, Stephen H. [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University,382 Via Pueblo Mall, Stanford, CA (United States); Stanford, Douglas [School of Natural Sciences, Institute for Advanced Study,1 Einstein Drive, Princeton, NJ (United States)
2016-08-17
We conjecture a sharp bound on the rate of growth of chaos in thermal quantum systems with a large number of degrees of freedom. Chaos can be diagnosed using an out-of-time-order correlation function closely related to the commutator of operators separated in time. We conjecture that the influence of chaos on this correlator can develop no faster than exponentially, with Lyapunov exponent λ{sub L}≤2πk{sub B}T/ℏ. We give a precise mathematical argument, based on plausible physical assumptions, establishing this conjecture.
HAMLET interacts with histones and chromatin in tumor cell nuclei.
Düringer, Caroline; Hamiche, Ali; Gustafsson, Lotta; Kimura, Hiroshi; Svanborg, Catharina
2003-10-24
HAMLET is a folding variant of human alpha-lactalbumin in an active complex with oleic acid. HAMLET selectively enters tumor cells, accumulates in their nuclei and induces apoptosis-like cell death. This study examined the interactions of HAMLET with nuclear constituents and identified histones as targets. HAMLET was found to bind histone H3 strongly and to lesser extent histones H4 and H2B. The specificity of these interactions was confirmed using BIAcore technology and chromatin assembly assays. In vivo in tumor cells, HAMLET co-localized with histones and perturbed the chromatin structure; HAMLET was found associated with chromatin in an insoluble nuclear fraction resistant to salt extraction. In vitro, HAMLET bound strongly to histones and impaired their deposition on DNA. We conclude that HAMLET interacts with histones and chromatin in tumor cell nuclei and propose that this interaction locks the cells into the death pathway by irreversibly disrupting chromatin organization.
Meson exchange and neutral weak currents
Energy Technology Data Exchange (ETDEWEB)
Beck, D.H. [Univ. of Illinois, Urbana, IL (United States)
1994-04-01
Measurements of parity-violating electron scattering asymmetries to determine weak neutral currents in nuclei will be effected by the presence of meson exchange currents. Present low momentum transfer calculations, based on a flavor independent framework, show these effects to be small. In general, however, as the momentum transfer increases to values typical of deep-inelastic scattering, fragmentation functions show a clear flavor dependence. It is suggested that a good experimental starting point for understanding the flavor dependence of meson production and exchange currents is the Q{sup 2} dependence of parity-violating asymmetry in inclusive single pion electroproduction. A CEBAF facility with doubled energy is necessary to approach momentum transfers where this process begins to scale.
Classical simulations of heavy-ion fusion reactions and weakly ...
Indian Academy of Sciences (India)
82, No. 5. — journal of. May 2014 physics pp. 879–891. Classical simulations of heavy-ion fusion reactions and weakly-bound projectile breakup reactions ... on the collision energy and the moment of inertia of the deformed nucleus. ... where each individual nucleus consists of a number of protons and neutrons, in some.
Reflection asymmetric shapes in nuclei
International Nuclear Information System (INIS)
Ahmad, I.; Carpenter, M.P.; Emling, H.
1989-01-01
Experimental data show that there is no even-even nucleus with a reflection asymmetric shape in its ground state. Maximum octupole- octupole correlations occur in nuclei in the mass 224 (N∼134, Z∼88) region. Parity doublets, which are the characteristic signature of octupole deformation, have been observed in several odd mass Ra, Ac and Pa nuclei. Intertwined negative and positive parity levels have been observed in several even-even Ra and Th nuclei above spin ∼8ℎ. In both cases, the opposite parity states are connected by fast El transitions. In some medium-mass nuclei intertwined negative and positive parity levels have also been observed above spin ∼7ℎ. The nuclei which exhibit octupole deformation in this mass region are 144 Ba, 146 Ba and 146 Ce; 142 Ba, 148 Ce, 150 Ce and 142 Xe do not show these characteristics. No case of parity doublet has been observed in the mass 144 region. 32 refs., 16 figs., 1 tab
Connections with Lsup(P) bounds on curvature
International Nuclear Information System (INIS)
Uhlenbeck, K.K.
1982-01-01
We show by means of the implicit function theorem that Coulomb gauges exist for fields over a bal in Rsup(n) when the integral Lsup(n/2) field norm is sufficiently small. We then are able to prove a weak compactness theorem for fields on compact manifolds with Lsup(n) integral norms bounded, p > n/2. (orig.)
On resonances and bound states of Smilansky Hamiltonian
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Lotoreichik, Vladimir; Tater, Miloš
2016-01-01
Roč. 7, č. 5 (2016), s. 789-802 ISSN 2220-8054 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : Smilansky Hamiltonian * resonances * resonance free region * weak coupling asymptotics * Riemann surface * bound states Subject RIV: BE - Theoretical Physics
International Nuclear Information System (INIS)
Camera, Stefano; Fornasa, Mattia; Fornengo, Nicolao; Regis, Marco
2013-01-01
Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.
Camera, Stefano; Fornasa, Mattia; Fornengo, Nicolao; Regis, Marco
2013-07-01
Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.
Energy Technology Data Exchange (ETDEWEB)
Camera, Stefano [CENTRA, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Lisboa (Portugal); Fornasa, Mattia [School of Physics and Astronomy, University of Nottingham, Nottingham (United Kingdom); Fornengo, Nicolao; Regis, Marco [Dipartimento di Fisica, Universita di Torino and INFN, Torino (Italy)
2013-07-01
Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.
Hypernuclear weak decay puzzle
International Nuclear Information System (INIS)
Barbero, C.; Horvat, D.; Narancic, Z.; Krmpotic, F.; Kuo, T.T.S.; Tadic, D.
2002-01-01
A general shell model formalism for the nonmesonic weak decay of the hypernuclei has been developed. It involves a partial wave expansion of the emitted nucleon waves, preserves naturally the antisymmetrization between the escaping particles and the residual core, and contains as a particular case the weak Λ-core coupling formalism. The extreme particle-hole model and the quasiparticle Tamm-Dancoff approximation are explicitly worked out. It is shown that the nuclear structure manifests itself basically through the Pauli principle, and a very simple expression is derived for the neutron- and proton-induced decays rates Γ n and Γ p , which does not involve the spectroscopic factors. We use the standard strangeness-changing weak ΛN→NN transition potential which comprises the exchange of the complete pseudoscalar and vector meson octets (π,η,K,ρ,ω,K * ), taking into account some important parity-violating transition operators that are systematically omitted in the literature. The interplay between different mesons in the decay of Λ 12 C is carefully analyzed. With the commonly used parametrization in the one-meson-exchange model (OMEM), the calculated rate Γ NM =Γ n +Γ p is of the order of the free Λ decay rate Γ 0 (Γ NM th congruent with Γ 0 ) and is consistent with experiments. Yet the measurements of Γ n/p =Γ n /Γ p and of Γ p are not well accounted for by the theory (Γ n/p th p th > or approx. 0.60Γ 0 ). It is suggested that, unless additional degrees of freedom are incorporated, the OMEM parameters should be radically modified
Protonic decay of oriented nuclei
International Nuclear Information System (INIS)
Kadmensky, S.G.
2002-01-01
On the basis of the multiparticle theory of protonic decay, the angular distributions of protons emitted by oriented spherical and deformed nuclei in the laboratory frame and in the internal coordinate frame of deformed parent nuclei are constructed with allowance for symmetry with respect to time inversion. It is shown that, because of the deep-subbarrier character of protonic decay, the adiabatic approximation is not applicable to describing the angular distributions of protons emitted by oriented deformed nuclei and that the angular distribution of protons in the laboratory frame does not coincide with that in the internal coordinate frame. It is demonstrated that these angular distributions coincide only if the adiabatic and the semiclassical approximation are simultaneously valid
International Nuclear Information System (INIS)
Oyamatsu, K.; Yamada, M.
1994-01-01
We report on the recent progress in understanding the matter in the crust of a neutron star. For nuclides in the outer crust, recently measured masses of neutron-rich nuclei enable us to determine more accurately the stable nuclide as a function of the matter density. In the inner crust, the compressible liquid-drop model predicts successive change of the nuclear shape, from sphere to cylinder, slab, cylindrical hole and spherical hole at densities just before the transition to uniform matter. In order to go beyond the liquiddrop model, we performed the Thomas-Fermi calculation paying special attention to the surface diffuseness, and have recently calculated the shell energies of the non-spherical nuclei. We have found from these studies that all these non-spherical nuclei exist stably in the above order even if we include the surface diffuseness and shell energies. (author)
Production of nuclei far from the beta stability line using intermediate-energy heavy ions
International Nuclear Information System (INIS)
Guerreau, D.
1986-05-01
The production of far unstable nuclei using heavy ion accelerators in the intermediate energy domain is reviewed. The various mechanisms responsible for the production of exotic species, mainly the projectile fragmentation and transfer reactions, are discussed, and the first experimental results presented. Results can be summarized as follows: existence of 4 new isotopes 22 C, 23 N, 29 Ne, 30 Ne; indication of bound character of 71 Ni, 72 Ni; clear evidence for bound character of 23 Si, 27 S, 31 Ar, 35 Ca; indications of bound character of 43 V, 46 Mn, 47 Mn, 48 Fe, 50 Co, 52 Co, 52 Ni, 55 Cu, 56 Cu
Measurement of weak radioactivity
Theodorsson , P
1996-01-01
This book is intended for scientists engaged in the measurement of weak alpha, beta, and gamma active samples; in health physics, environmental control, nuclear geophysics, tracer work, radiocarbon dating etc. It describes the underlying principles of radiation measurement and the detectors used. It also covers the sources of background, analyzes their effect on the detector and discusses economic ways to reduce the background. The most important types of low-level counting systems and the measurement of some of the more important radioisotopes are described here. In cases where more than one type can be used, the selection of the most suitable system is shown.
DEFF Research Database (Denmark)
Kohlenbach, Ulrich Wilhelm
2002-01-01
We show that the so-called weak Markov's principle (WMP) which states that every pseudo-positive real number is positive is underivable in E-HA + AC. Since allows one to formalize (atl eastl arge parts of) Bishop's constructive mathematics, this makes it unlikely that WMP can be proved within...... the framework of Bishop-style mathematics (which has been open for about 20 years). The underivability even holds if the ine.ective schema of full comprehension (in all types) for negated formulas (in particular for -free formulas) is added, which allows one to derive the law of excluded middle...
Roles of nuclear weak rates on the evolution of degenerate cores in stars
Directory of Open Access Journals (Sweden)
Suzuki Toshio
2017-01-01
Full Text Available Electron-capture and β-decay rates in stellar environments are evaluated with the use of new shell-model Hamiltonians for sd-shell and pf-shell nuclei as well as for nuclei belonging to the island of inversion. Important role of the nuclear weak rates on the final evolution of stellar degenerate cores is presented. The weak interaction rates for sd-shell nuclei are calculated to study nuclear Urca processes in O-Ne-Mg cores of stars with 8-10 M⊙ (solar mass and their effects on the final fate of the stars. Nucleosynthesis of iron-group elements in Type Ia supernova explosions are studied with the weak rates for pf-shell nuclei. The problem of the neutron-rich iron-group isotope over-production compared to the solar abundances is shown to be nearly solved with the use of the new rates and explosion model of slow defraglation with delayed detonation. Evaluation of the weak rates is extended to the island of inversion and the region of neutron-rich nuclei near 78Ni, where two major shells contribute to their configurations.
Neutron scattering on deformed nuclei
International Nuclear Information System (INIS)
Hansen, L.F.; Haight, R.C.; Pohl, B.A.; Wong, C.; Lagrange, C.
1984-09-01
Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9 Be, C, 181 Ta, 232 Th, 238 U and 239 Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonable good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP
Octupole shapes in heavy nuclei
International Nuclear Information System (INIS)
Ahmad, I.
1994-01-01
Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets
International Nuclear Information System (INIS)
Nomura, T.
1991-12-01
The Exotic Nuclei Arena planned in Japanese Hadron Project aims to accelerate various unstable nuclei produced in 1-GeV proton-induced reactions up to 6.5 MeV/u by means of heavy-ion linacs. The present status of research and development for the Earena is briefly reported. The construction of the prototype facility to accelerate unstable beams up to 0.8 MeV/u is planned in 1992-94, in which the existing cyclotron in INS is used as the primary accelerator. (author)
Spinodal decomposition of atomic nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, P. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Colonna, M.; Guarnera, A. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)]|[LNS, Catania (Italy)
1996-12-31
Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.). 21 refs.
Spinodal decomposition of atomic nuclei
International Nuclear Information System (INIS)
Chomaz, P.; Colonna, M.; Guarnera, A.
1996-01-01
Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.)
Are there superheavy atomic nuclei
International Nuclear Information System (INIS)
Herrmann, G.
1982-04-01
The author presents a populary introduction to the formation of nuclei with special regards to superheavy nuclei. After a general description of the methods of physics the atomic hypothesis is considered. Thereafter the structure of the nucleus is discussed, and the different isotopes are considered. Then radioactivity is described as an element transmutation. Thereafter the thermonuclear reactions in the sun are considered. Then the synthesis of elements using heavy ion reactions is described. In this connection the transuranium elements and the superheavy elements are considered. (orig./HSI) [de
The mechanism of total disintegration of heavy nuclei by fast hadrons and nuclei
International Nuclear Information System (INIS)
Strugalska-Gola, E.; Strugalski, Z.
1997-01-01
The mechanism of the total disintegration of atomic nuclei by fast hadrons and nuclei is considered. The passage of energetic hadrons through layers of intranuclear matter, accompanied by emission of fast nucleons with kinetic energies from about 20 up to about 500 MeV from definite local small regions in the nuclei around projectile courses in them, allows one to explain simply the occurrence of the total destruction of nuclei involved in the collisions. Light nuclei may be totally disintegrated by fast hadrons and nuclei; heavier nuclei may be totally disintegrated only in central collisions of nuclei with similar mass numbers
Weakly Supervised Dictionary Learning
You, Zeyu; Raich, Raviv; Fern, Xiaoli Z.; Kim, Jinsub
2018-05-01
We present a probabilistic modeling and inference framework for discriminative analysis dictionary learning under a weak supervision setting. Dictionary learning approaches have been widely used for tasks such as low-level signal denoising and restoration as well as high-level classification tasks, which can be applied to audio and image analysis. Synthesis dictionary learning aims at jointly learning a dictionary and corresponding sparse coefficients to provide accurate data representation. This approach is useful for denoising and signal restoration, but may lead to sub-optimal classification performance. By contrast, analysis dictionary learning provides a transform that maps data to a sparse discriminative representation suitable for classification. We consider the problem of analysis dictionary learning for time-series data under a weak supervision setting in which signals are assigned with a global label instead of an instantaneous label signal. We propose a discriminative probabilistic model that incorporates both label information and sparsity constraints on the underlying latent instantaneous label signal using cardinality control. We present the expectation maximization (EM) procedure for maximum likelihood estimation (MLE) of the proposed model. To facilitate a computationally efficient E-step, we propose both a chain and a novel tree graph reformulation of the graphical model. The performance of the proposed model is demonstrated on both synthetic and real-world data.
International Nuclear Information System (INIS)
Ritchie, Burke
2006-01-01
The Hamiltonian for Dirac's second-order equation depends nonlinearly on the potential V and the energy E. For this reason the magnetic contribution to the Hamiltonian for s-waves, which has a short range, is attractive for a repulsive Coulomb potential (V>0) and repulsive for an attractive Coulomb potential (V 2 . Usually solutions are found in the regime E=mc 2 +ε , where except for high Z, ε 2 . Here it is shown that for V>0 the attractive magnetic term and the linear repulsive term combine to support a bound state near E=0.5mc 2 corresponding to a binding energy E b =-ε =0.5mc 2
Neutron skin studies of medium and heavy nuclei
Directory of Open Access Journals (Sweden)
Thiel M.
2014-06-01
Full Text Available The recent PREX experiment at JLab has demonstrated the sensitivity of parity violating electron scattering to the neutron density, meanwhile outlining its major experimental challenges. On the other side, intermediate energy photons are an ideal probe for studying the properties of strongly interacting matter from the nuclear scale down to the sub-nuclear components of the nucleus. Among others coherent pion photoproduction can provide information on the existence and nature of neutron skins in nuclei. The simultaneous combination of different techniques allows a systematic determination across the periodic table thus benchmarking modern calculation. Recently a systematic investigation of the latter method has been exploited at MAMI (Mainz. At MESA the same setup as in the measurement of the weak mixing angle can be used to determine the parity-violating asymmetry for polarized electrons scattered on heavy nuclei with a 1% resolution. Status and prospects of the projects are presented.
Transitional nuclei near shell closures
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India and Present Address: Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)
2014-08-14
High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.
Cluster structure in Cf nuclei
International Nuclear Information System (INIS)
Singh, Shailesh K.; Biswal, S.K.; Bhuyan, M.; Patra, S.K.; Gupta, R.K.
2014-01-01
Due to the availability of advance experimental facilities, it is possible to probe the nuclei upto their nucleon level very precisely and analyzed the internal structure which will help us to resolve some mysterious problem of the decay of nuclei. Recently, the relativistic nuclear collision, confirmed the α cluster type structure in the 12 C which is the mile stone for the cluster structure in nuclei. The clustering phenomena in light and intermediate elements in nuclear chart is very interesting. There is a lot of work done by our group in the clustering behaviour of the nuclei. In this paper, the various prospectus of clustering in the isotopes of Cf nucleus including fission state is discussed. Here, 242 Cf isotope for the analysis, which is experimentally known is taken. The relativistic mean field model with well established NL3 parameter set is taken. For getting the exact ground state configuration of the isotopes, the calculation for minimizing the potential energy surface is performed by constraint method. The clustering structure of other Cf isotopes is discussed
Nuclear astrophysics of light nuclei
DEFF Research Database (Denmark)
Fynbo, Hans Otto Uldall
2013-01-01
A review of nuclear astrophysics of light nuclei using radioactive beams or techniques developed for radioactive beams is given. We discuss Big Bang nucleosynthesis, with special focus on the lithium problem, aspects of neutrino-physics, helium-burning and finally selected examples of studies...
Particle detection from oriented nuclei
International Nuclear Information System (INIS)
Wouters, J.; Moor, P. de; Schuurmans, P.; Severijns, N.; Vanderpoorten, W.; Vanneste, L.
1992-01-01
A survey is given of particle emission from nuclei that have been spin oriented by cryogenical means. Experiments and recent developments with detectors in the low temperature environment and their on-line application are reviewed. The most recent results are mentioned. Some phenomena to be unraveled in future studies are pointed out. (orig.)
Rotational damping motion in nuclei
International Nuclear Information System (INIS)
Egido, J.L.; Faessler, A.
1991-01-01
The recently proposed model to explain the mechanism of the rotational motion damping in nuclei is exactly solved. When compared with the earlier approximative solution, we find significative differences in the low excitation energy limit (i.e. Γ μ 0 ). For the strength functions we find distributions going from the Wigner semicircle through gaussians to Breit-Wigner shapes. (orig.)
Percolation and multifragmentation of nuclei
International Nuclear Information System (INIS)
Shmakov, S.Yu.; Uzhinskij, V.V.
1989-01-01
A method to build the 'cold' nuclei as percolation clusters is suggested. Within the framework of definite assumptions of the character of nucleon-nucleon couplings breaking resulting from the nuclear reactions as description of the multifragmentation process in the hadron-nucleus and nucleus-nucleus reactions at high energies is obtained. 19 refs.; 6 figs
Octupole correlation effects in nuclei
International Nuclear Information System (INIS)
Chasman, R.R.
1992-01-01
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions
Electron scattering for exotic nuclei
Indian Academy of Sciences (India)
2014-11-04
Nov 4, 2014 ... A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world's first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density ...
Mogami manifolds, nuclei, and 3D simplicial gravity
Energy Technology Data Exchange (ETDEWEB)
Benedetti, Bruno, E-mail: bruno@math.miami.edu
2017-06-15
Mogami introduced in 1995 a large class of triangulated 3-dimensional pseudomanifolds, henceforth called “Mogami pseudomanifolds”. He proved an exponential bound for the size of this class in terms of the number of tetrahedra. The question of whether all 3-balls are Mogami has remained open since; a positive answer would imply a much-desired exponential upper bound for the total number of 3-balls (and 3-spheres) with N tetrahedra. Here we provide a negative answer: many 3-balls are not Mogami. On the way to this result, we characterize the Mogami property in terms of nuclei, in the sense of Collet–Eckmann–Younan: “The only three-dimensional Mogami nucleus is the tetrahedron”.
Exotic nuclei with charm and bottom ﬂavor
Directory of Open Access Journals (Sweden)
Yasui S.
2010-04-01
Full Text Available We discuss the possibility of existence of exotic nuclei containing charm and bottom mesons. We study the interaction between $ar{D}$ (B mesons and nucleons from view of heavy quark symmetry, and derive the one pion exchange potentials. We apply these potentials to the two body system of $ar{D}$ (B meson and nucleon N , and ﬁnd there are possible stable bound states with spin JP = 1/2− and isospin I = 0. We ﬁnd that the tensor interaction mixing $ar{D}$N and $ar{D}$*N (BN and B*N plays an important role. We also qualitatively discuss the possible bound states of $ar{D}$ (B meson and two nucleons.
First observation of bound excited states in the A/Z = 3 nucleus 15B
International Nuclear Information System (INIS)
Dobradi, Zs.; Sohler, D.; Azaiez, F.
2004-01-01
Complete text of publication follows. Structure of strongly neutron rich nuclei, especially of those lying close to the neutron drip line came into the focus of interest. Among others, the structure of neutron rich Boron isotopes also attracted attention in the last decade. The nuclei 15 B, 17 B and 19 B are particle stable, while the isotopes with even mass number are unstable against neutron emission. Even the neutron rich Boron isotopes with odd mass number have a low neutron binding energy, which is a sign of their weakly bound nature. As a common effect of the weak binding and of the large neutron excess, neutron skin or halo can also develop already in the isotope 15 B with A/Z = 3. Structure of the nucleus 15 B has been investigated by in-beam γ-spectroscopic study of the 9 Be + 36 S fragmentation reaction at GANIL, France. The emerging fragments were identified by use of a standard ΔE-time-of-fight technique with help of the SPEG spectrograph. γ-ray energies, intensities and γγ coincidences have been measured in coincidence with the projectile like fragments by 74 BaF 2 detectors of the Chateau de crystal. On the basis of the γ-spectroscopic information the level scheme presented in Figure 1 was constructed. The level scheme is shown together with the results of di rent model calculations. The common in predictions of these models is that all of them suggest a ground state band with the spin sequence 3/2 - , 5/2 - and 7/2 - , as well as a 1/2 - state, which involves a proton single particle excitation. The shell model calculations (SM) predict similar moments of inertia, strongly different from that of the antisymmetrized molecular dynamics calculations (AMD). The experimentally observed states can be assigned to the members of the rotational band on the basis of their decay properties. The experimental results confirm the predictions of the shell model. (author)
Wee partons in large nuclei: from virtual dream to hard reality
International Nuclear Information System (INIS)
Venugopalan, R.
1995-01-01
We construct a weak coupling, many body theory to compute parton distributions in large nuclei for x -1/3 . The wee partons are highly coherent, non-Abelian Weizsaecker-Williams fields. Radiative corrections to the classical results are discussed. The parton distributions for a single nucleus provide the initial conditions for the dynamical evolution of matter formed in ultrarelativistic nuclear collisions. (orig.)
Bounding approaches to system identification
Norton, John; Piet-Lahanier, Hélène; Walter, Éric
1996-01-01
In response to the growing interest in bounding error approaches, the editors of this volume offer the first collection of papers to describe advances in techniques and applications of bounding of the parameters, or state variables, of uncertain dynamical systems. Contributors explore the application of the bounding approach as an alternative to the probabilistic analysis of such systems, relating its importance to robust control-system design.
Market access through bound tariffs
DEFF Research Database (Denmark)
Sala, Davide; Yalcin, Erdal; Schröder, Philipp
2010-01-01
on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...... margin of trade. We find that bound tariffs are more effective with higher risk destination markets, that a large binding overhang may still command substantial market access, and that reductions in bound tariffs generate effective market access even when bound rates are above current and longterm...
Market Access through Bound Tariffs
DEFF Research Database (Denmark)
Sala, Davide; Schröder, Philipp J.H.; Yalcin, Erdal
on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...... margin of trade. We find that bound tariffs are more effective with higher risk destination markets, that a large binding overhang may still command substantial market access, and that reductions in bound tariffs generate effective market access even when bound rates are above current and long...
Quivers of Bound Path Algebras and Bound Path Coalgebras
Directory of Open Access Journals (Sweden)
Dr. Intan Muchtadi
2010-09-01
Full Text Available bras and coalgebras can be represented as quiver (directed graph, and from quiver we can construct algebras and coalgebras called path algebras and path coalgebras. In this paper we show that the quiver of a bound path coalgebra (resp. algebra is the dual quiver of its bound path algebra (resp. coalgebra.
Study of weak solutions for parabolic variational inequalities with nonstandard growth conditions.
Dong, Yan
2018-01-01
In this paper, we study the degenerate parabolic variational inequality problem in a bounded domain. First, the weak solutions of the variational inequality are defined. Second, the existence and uniqueness of the solutions in the weak sense are proved by using the penalty method and the reduction method.
Influence of low-energy scattering on loosely bound states
International Nuclear Information System (INIS)
Sparenberg, Jean-Marc; Capel, Pierre; Baye, Daniel
2010-01-01
Compact algebraic equations are derived that connect the binding energy and the asymptotic normalization constant (ANC) of a subthreshold bound state with the effective-range expansion of the corresponding partial wave. These relations are established for positively charged and neutral particles, using the analytic continuation of the scattering (S) matrix in the complex wave-number plane. Their accuracy is checked on simple local potential models for the 16 O+n, 16 O+p, and 12 C+α nuclear systems, with exotic nuclei and nuclear astrophysics applications in mind.
Cavitation nuclei measurements - A review
International Nuclear Information System (INIS)
Billet, M.L.
1985-01-01
The measurement of cavitation nuclei has been the goal of many cavitation research laboratories and has resulted in the development of many methods. Two significantly different approaches have been developed. One is to measure the particulate-microbubble distribution by utilizing acoustical, electrical or optical methods. The other approach measures a liquid tension and a rate of cavitation events for a liquid in order to establish a cavitation susceptibility. Comparisons between various methods indicate that most methods are capable of giving an indication of the nuclei distribution. Measurements obtained in the ocean environment indicate an average of three bubbles per cubic centimeter are present; whereas, water tunnel bubble distributions vary from much less than one to over a hundred per cubic centimeter
Phonon operators in deformed nuclei
International Nuclear Information System (INIS)
Soloviev, V.G.
1981-01-01
For the description of the excited states in deformed nuclei new phonon operators are introduced, which depend on the sign of the angular momentum projection onto the symmetry axis of a deformed nucleus. In the calculations with new phonons the Pauli principle is correctly taken into account in the two-phonon components of the wave functions. There is a difference in comparison with the calculation with phonons independent of the sign of the angular momentum projection. The new phonons should be used in deformed nuclei if the Pauli principle is consistently taken into account and in the calculations with the excited state wave functions having the components with more than one phonon operator [ru
Phonon operators for deformed nuclei
International Nuclear Information System (INIS)
Solov'ev, V.G.
1982-01-01
The mathematical formalism with the phonon operators independent of the signature of the angular momentum projection turns out to be inadequate for describing excited states of deformed nuclei. New phonon operators are introduced which depend on the signature of the angular momentum projection on the symmetry axis of a deformed nucleus. It is shown that the calculations with the new phonons take correctly into account the Pauli principle in two-phonon components of wave functions. The results obtained differ from those given by the phonons independent of the signature of the angular momentum projection. The new phonons must be used in deformed nuclei at taking systematically the Pauli principle into account and in calculations involving wave functions of excited states having components with more than one-phonon operator
Nuclear treasure island [superheavy nuclei
CERN. Geneva
1999-01-01
Summary form only given. Soon after the experiments at Dubna, which synthesized element 114 and made the first footprints on the beach of the "island of nuclear stability", two new superheavy elements have been discovered at the Lawrence Berkeley National Laboratory. Element 118 and its immediate decay product, element 116, were manufactured at Berkeley's 88 inch cyclotron by fusing targets of lead-208 with an intense beam of 449 MeV krypton-86 ions. Although both new nuclei almost instantly decay into lighter ones, the decay sequence is consistent with theories that have long predicted the island of stability for nuclei with approximately 114 protons and 184 neutrons. Theorist Robert Smolanczuk, visiting from the Soltan Institute for Nuclear Studies in Poland, had calculated that this reaction should have particularly favourable production rates. Now that this route has been signposted, similar reactions could be possible: new elements and isotopes, tests of nuclear stability and mass models, and a new under...
Moessbauer effects on oriented nuclei
International Nuclear Information System (INIS)
Sayouti, E.H.
1984-01-01
Standard nuclear orientation methods (not sensitive to the polarization) do not give information on the sign of the magnetic moment. Mossbauer effect separates right-hand and left-hand circularly polarized components, thus its detection on oriented nuclei (T approximately 10 mK) gives the sign of the magnetic moment of oriented state. In this thesis we applied this method to study the 3/2 - ground states of 191 Pt and 193 Os, which are in the prolate-oblate transition region, where assignement of experimental levels to theoretical states is often umbiguous. We show that for those nuclei the sign of the magnetic moment is the signature of the configuration, and its determination establishes the correspondance between experimental and theoretical levels [fr
International Nuclear Information System (INIS)
Beck, Christian
2010-01-01
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is presently one of the domains of heavy-ion nuclear physics facing both the greatest challenges and opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physics decided to team up in producing a comprehensive collection of lectures and tutorial reviews covering the field. This first volume, gathering seven extensive lectures, covers the follow topics: - Cluster Radioactivity - Cluster States and Mean Field Theories - Alpha Clustering and Alpha Condensates - Clustering in Neutron-rich Nuclei - Di-neutron Clustering - Collective Clusterization in Nuclei - Giant Nuclear Molecules By promoting new ideas and developments while retaining a pedagogical nature of presentation throughout, these lectures will both serve as a reference and as advanced teaching material for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)
International Nuclear Information System (INIS)
Oset, E.
1980-01-01
A short review of the topic of mesons in nuclei is exposed paying particular attention to the relationship between several mesonic processes. Special emphasis is put into the microscopic pictures that can ultimately relate all these processes with the elementary coupling of mesons to the nuclear hadronic components. The importance of the short range part of the nuclear interaction opens the doors to a more basic understanding in terms of the quark components of nucleons and isobars. (orig.)
Exclusive photoreactions on light nuclei
International Nuclear Information System (INIS)
Maruyama, K.
1989-08-01
The mechanism of photon absorption on light nuclei in the Δ-resonance region is discussed. The present status of experimental results is briefly summarized. A recent data from 1.3-GeV Tokyo ES using a π sr spectrometer is introduced. Exclusive measurements of the photodisintegration of 3 He and 4 He may be a clear way to identify 2N, 3N and 4N absorptions. (author)
Fission barriers of light nuclei
International Nuclear Information System (INIS)
Grotowski, K.; Planeta, R.; Blann, M.; Komoto, T.
1989-01-01
Experimental fission excitation functions for compound nuclei /sup 52/Fe, /sup 49/Cr, /sup 46/V, and /sup 44/Ti formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems
A new unexpected feature of superdeformed nuclei: strange degeneracies and their origin
International Nuclear Information System (INIS)
Dudek, J.
1990-01-01
Unexpected similarities between the superdeformed bands found recently in many nuclei of the mass A ∼ 150 and A ∼ 190 regions and the physical sense of this discovery are discussed. These similarities manifest themselves through the existence of nearly identical sequences of transitions belonging to two neighboring nuclei, and by now numerous nuclear pairs manifesting this feature have been found. The underlying microscopic mechanism is traced back to two independent effects: a readjustment of nuclear deformation diminishing the role of alignment of the least bound nucleus, and, the pseudospin symmetry, responsible for an approximate decoupling of the orbital and the intrinsic (pseudo) spin-degrees of freedom. 9 figs
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)
International Nuclear Information System (INIS)
Armbruster, P.; Hessberger, F.P.
1998-01-01
In the last 60 years physicists have created 20 artificial elements beyond uranium. In 1934 Enrico Fermi predicted the creation of new elements by bombarding atoms with neutrons. This method led to the discovery of neptunium (Z=93), plutonium, americium, curium, berkelium, californium, einsteinium and fermium (Z=100). In fact the capture of a neutron is followed by a beta-decay which increases the atomic number (Z) by one unit. Beyond Z=100 beta-decay no more occurs so a new approach was necessary. Between the American Lawrence Berkeley Laboratory and the Russian Dubna Institute a fierce competition broke out to produce new elements by bombarding transuranium nuclei with light elements such as helium, carbon, nitrogen. This new method required heavy equipment: ion accelerator and detectors but led to the creation of all the elements from Z=101 to Z=106. A new idea was to provoke the fusion of heavy nuclei such as lead and bismuth with colliding argon, nickel or zinc ion beams. This method called 'cold fusion' opened the way to reach the nuclei beyond Z=107. In 1996 the element Z=112 was the last discovered. The next step could be the element Z=114 for which a particular stability is expected. (A.C.)
International Nuclear Information System (INIS)
Sugimoto, Kenzo
1982-01-01
An experiment is proposed to determine systematically the radii of the nuclei produced through the projectile fragmentation process in high energy heavy-ion collision. The measurement of total reaction cross section using the projectile fragments of a single nuclide on a target give information about nuclear radii. The production cross section of the fragments is appreciable for many nuclides. Therefore, it is possible to map systematically the reaction radii of the nuclei which can be produced as the projectile fragments. In an experiment using the projectile fragments as the incident beam, the cross section can be expressed as a function of the radii of a projectile and a target. An experiment with He-8 produced by the fragmentation of C-12 is proposed. The He-8 has four neutrons in the p-3/2 orbit outside the He-4 core. Proton and neutron distributions for He isotopes were calculated on the basis of the Hartree-Fock method. The information related to this kind of distribution can be obtained by the proposed experiment. The nuclear structure effect is seen in the nuclear radii of other unstable nuclei. The experimental examples of the isotope shift measurement and the excitation energy are presented. (Kato, T.)
Density functional theory of nuclei
International Nuclear Information System (INIS)
Terasaki, Jun
2008-01-01
The density functional theory of nuclei has come to draw attention of scientists in the field of nuclear structure because the theory is expected to provide reliable numerical data in wide range on the nuclear chart. This article is organized to present an overview of the theory to the people engaged in the theory of other fields as well as those people in the nuclear physics experiments. At first, the outline of the density functional theory widely used in the electronic systems (condensed matter, atoms, and molecules) was described starting from the Kohn-Sham equation derived on the variational principle. Then the theory used in the field of nuclear physics was presented. Hartree-Fock and Hartree-Fock-Bogolyubov approximation by using Skyrme interaction was explained. Comparison of the results of calculations and experiments of binding energies and ground state mean square charge radii of some magic number nuclei were shown. The similarity and dissimilarity between the two streams were summarized. Finally the activities of the international project of Universal Nuclear Energy Density Functional (UNEDF) which was started recently lead by US scientist was reported. This project is programmed for five years. One of the applications of the project is the calculation of the neutron capture cross section of nuclei on the r-process, which is absolutely necessary for the nucleosynthesis research. (S. Funahashi)
Thermodynamical description of excited nuclei
International Nuclear Information System (INIS)
Bonche, P.
1989-01-01
In heavy ion collisions it has been possible to obtain composite systems at rather high excitation energies corresponding to temperatures of several MeV. The theoretical studies of these systems are based on concepts borrowed from thermodynamics or statistical physics, such as the temperature. In these lectures, we present the concepts of statistical physics which are involved in the physics of heavy ion as they are produced nowadays in the laboratory and also during the final stage of a supernova collapse. We do not attempt to describe the reaction mechanisms which yield such nuclear systems nor their decay by evaporation or fragmentation. We shall only study their static properties. The content of these lectures is organized in four main sections. The first one gives the basic features of statistical physics and thermodynamics necessary to understand quantum mechanics at finite temperature. In the second one, we present a study of the liquid-gas phase transition in nuclear physics. A phenomenological approach of the stability of hot nuclei follows. The microscopic point of view is proposed in the third part. Starting from the basic concepts derived in the first part, it provides a description of excited or hot nuclei which confirms the qualitative results of the second part. Furthermore it gives a full description of most properties of these nuclei as a function of temperature. Finally in the last part, a microscopic derivation of the equation of state of nuclear matter is proposed to study the collapse of a supernova core
Usefulness of bound-state approximations in reaction theory
International Nuclear Information System (INIS)
Adhikari, S.K.
1981-01-01
A bound-state approximation when applied to certain operators, such as the many-body resolvent operator for a two-body fragmentation channel, in many-body scattering equations, reduces such equations to equivalent two-body scattering equations which are supposed to provide a good description of the underlying physical process. In this paper we test several variants of bound-state approximations in the soluble three-boson Amado model and find that such approximations lead to weak and unacceptable kernels for the equivalent two-body scattering equations and hence to a poor description of the underlying many-body process
Re-derived overclosure bound for the inert doublet model
Biondini, S.; Laine, M.
2017-08-01
We apply a formalism accounting for thermal effects (such as modified Sommerfeld effect; Salpeter correction; decohering scatterings; dissociation of bound states), to one of the simplest WIMP-like dark matter models, associated with an "inert" Higgs doublet. A broad temperature range T ˜ M/20 . . . M/104 is considered, stressing the importance and less-understood nature of late annihilation stages. Even though only weak interactions play a role, we find that resummed real and virtual corrections increase the tree-level overclosure bound by 1 . . . 18%, depending on quartic couplings and mass splittings.
Higgs mass upper bound in the O(4) approximation
International Nuclear Information System (INIS)
Lin, L.
1991-01-01
In this paper the theoretical breakdown of the minimal standard model in four dimension is investigated when the mass of the Higgs particle is larger than the weak interaction scale. The triviality arguement for an upper bound on the Higgs mass is made quantitative on the lattice in large scale simulations of the spontaneously broken Higgs sector. The authors obtain an upper bound m H ≅640 GeV on the Higgs mass at a dimensionless correlation length ξ = 2 in lattice units.units
Bounds for Asian basket options
Deelstra, Griselda; Diallo, Ibrahima; Vanmaele, Michèle
2008-09-01
In this paper we propose pricing bounds for European-style discrete arithmetic Asian basket options in a Black and Scholes framework. We start from methods used for basket options and Asian options. First, we use the general approach for deriving upper and lower bounds for stop-loss premia of sums of non-independent random variables as in Kaas et al. [Upper and lower bounds for sums of random variables, Insurance Math. Econom. 27 (2000) 151-168] or Dhaene et al. [The concept of comonotonicity in actuarial science and finance: theory, Insurance Math. Econom. 31(1) (2002) 3-33]. We generalize the methods in Deelstra et al. [Pricing of arithmetic basket options by conditioning, Insurance Math. Econom. 34 (2004) 55-57] and Vanmaele et al. [Bounds for the price of discrete sampled arithmetic Asian options, J. Comput. Appl. Math. 185(1) (2006) 51-90]. Afterwards we show how to derive an analytical closed-form expression for a lower bound in the non-comonotonic case. Finally, we derive upper bounds for Asian basket options by applying techniques as in Thompson [Fast narrow bounds on the value of Asian options, Working Paper, University of Cambridge, 1999] and Lord [Partially exact and bounded approximations for arithmetic Asian options, J. Comput. Finance 10 (2) (2006) 1-52]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and time-to-maturity.
Product differentiation under bounded rationality
Vermeulen, B.; Poutré, La J.A.; Kok, de A.G.; Pyka, A.; Handa, H.; Ishibuchi, H.; Ong, Y.-S.; Tan, K.-C.
2015-01-01
We study product differentiation equilibria and dynamics on the Salop circle under bounded rationality. Due to bounded rationality, firms tend to agglomerate in pairs. Upon adding a second tier of component suppliers, downstream assemblers may escape pairwise horizontal agglomeration. Moreover, we
The colours of Hubble Sc galaxy nuclei
International Nuclear Information System (INIS)
Iskudaryan, S.G.
1975-01-01
The colorimetric data on the nuclei of the Sc galaxies are given. Comparison of the following parameters: color of a nucleus, integral color of a galaxy, Byurakan class, and spectral type of normal spirals gives the possibility to conclude: (1) The colors of the nuclei of the Sc galaxies have a high dispersion in its values. In all Byurakan classes the galaxies with intensely red and blue nuclei occur; (2) Some Sc galaxies exhibit a discrepancy between the spectral and morphological types. The results of colorimetry of nuclei indicate that almost all such Sc galaxies have intensely red nuclei which, naturally, provide for these late spectral types. It can be assumed that the intensely red color of the nuclei of such Sc galaxies is a result of a new type of activity of these nuclei; and (3) some Sc galaxies show the characteristics of the Markarian objects
Metabolism of organically bound tritium
International Nuclear Information System (INIS)
Travis, C.C.
1984-01-01
The classic methodology for estimating dose to man from environmental tritium ignores the fact that organically bound tritium in foodstuffs may be directly assimilated in the bound compartment of tissues without previous oxidation. We propose a four-compartment model consisting of a free body water compartment, two organic compartments, and a small, rapidly metabolizing compartment. The utility of this model lies in the ability to input organically bound tritium in foodstuffs directly into the organic compartments of the model. We found that organically bound tritium in foodstuffs can increase cumulative total body dose by a factor of 1.7 to 4.5 times the free body water dose alone, depending on the bound-to-loose ratio of tritium in the diet. Model predictions are compared with empirical measurements of tritium in human urine and tissue samples, and appear to be in close agreement. 10 references, 4 figures, 3 tables
General gauge mediation at the weak scale
Energy Technology Data Exchange (ETDEWEB)
Knapen, Simon [Berkeley Center for Theoretical Physics,University of California, Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, CA 94720 (United States); Redigolo, Diego [Sorbonne Universités, UPMC Univ Paris 06,UMR 7589, LPTHE, F-75005, Paris (France); CNRS, UMR 7589,LPTHE, F-75005, Paris (France); Shih, David [New High Energy Theory Center, Rutgers University,Piscataway, NJ 08854 (United States)
2016-03-09
We completely characterize General Gauge Mediation (GGM) at the weak scale by solving all IR constraints over the full parameter space. This is made possible through a combination of numerical and analytical methods, based on a set of algebraic relations among the IR soft masses derived from the GGM boundary conditions in the UV. We show how tensions between just a few constraints determine the boundaries of the parameter space: electroweak symmetry breaking (EWSB), the Higgs mass, slepton tachyons, and left-handed stop/sbottom tachyons. While these constraints allow the left-handed squarks to be arbitrarily light, they place strong lower bounds on all of the right-handed squarks. Meanwhile, light EW superpartners are generic throughout much of the parameter space. This is especially the case at lower messenger scales, where a positive threshold correction to m{sub h} coming from light Higgsinos and winos is essential in order to satisfy the Higgs mass constraint.
A Weak Comparison Principle for Reaction-Diffusion Systems
Directory of Open Access Journals (Sweden)
José Valero
2012-01-01
Full Text Available We prove a weak comparison principle for a reaction-diffusion system without uniqueness of solutions. We apply the abstract results to the Lotka-Volterra system with diffusion, a generalized logistic equation, and to a model of fractional-order chemical autocatalysis with decay. Moreover, in the case of the Lotka-Volterra system a weak maximum principle is given, and a suitable estimate in the space of essentially bounded functions L∞ is proved for at least one solution of the problem.
Zilberberg, Oded; Romito, Alessandro; Gefen, Yuval
2013-01-01
Weak value (WV) is a quantum mechanical measurement protocol, proposed by Aharonov, Albert, and Vaidman. It consists of a weak measurement, which is weighed in, conditional on the outcome of a later, strong measurement. Here we define another two-step measurement protocol, null weak value (NVW), and point out its advantages as compared to WV. We present two alternative derivations of NWVs and compare them to the corresponding derivations of WVs.
Accurate Detection of Dysmorphic Nuclei Using Dynamic Programming and Supervised Classification.
Verschuuren, Marlies; De Vylder, Jonas; Catrysse, Hannes; Robijns, Joke; Philips, Wilfried; De Vos, Winnok H
2017-01-01
A vast array of pathologies is typified by the presence of nuclei with an abnormal morphology. Dysmorphic nuclear phenotypes feature dramatic size changes or foldings, but also entail much subtler deviations such as nuclear protrusions called blebs. Due to their unpredictable size, shape and intensity, dysmorphic nuclei are often not accurately detected in standard image analysis routines. To enable accurate detection of dysmorphic nuclei in confocal and widefield fluorescence microscopy images, we have developed an automated segmentation algorithm, called Blebbed Nuclei Detector (BleND), which relies on two-pass thresholding for initial nuclear contour detection, and an optimal path finding algorithm, based on dynamic programming, for refining these contours. Using a robust error metric, we show that our method matches manual segmentation in terms of precision and outperforms state-of-the-art nuclear segmentation methods. Its high performance allowed for building and integrating a robust classifier that recognizes dysmorphic nuclei with an accuracy above 95%. The combined segmentation-classification routine is bound to facilitate nucleus-based diagnostics and enable real-time recognition of dysmorphic nuclei in intelligent microscopy workflows.
Accurate Detection of Dysmorphic Nuclei Using Dynamic Programming and Supervised Classification.
Directory of Open Access Journals (Sweden)
Marlies Verschuuren
Full Text Available A vast array of pathologies is typified by the presence of nuclei with an abnormal morphology. Dysmorphic nuclear phenotypes feature dramatic size changes or foldings, but also entail much subtler deviations such as nuclear protrusions called blebs. Due to their unpredictable size, shape and intensity, dysmorphic nuclei are often not accurately detected in standard image analysis routines. To enable accurate detection of dysmorphic nuclei in confocal and widefield fluorescence microscopy images, we have developed an automated segmentation algorithm, called Blebbed Nuclei Detector (BleND, which relies on two-pass thresholding for initial nuclear contour detection, and an optimal path finding algorithm, based on dynamic programming, for refining these contours. Using a robust error metric, we show that our method matches manual segmentation in terms of precision and outperforms state-of-the-art nuclear segmentation methods. Its high performance allowed for building and integrating a robust classifier that recognizes dysmorphic nuclei with an accuracy above 95%. The combined segmentation-classification routine is bound to facilitate nucleus-based diagnostics and enable real-time recognition of dysmorphic nuclei in intelligent microscopy workflows.
Weak openness and almost openness
Directory of Open Access Journals (Sweden)
David A. Rose
1984-01-01
Full Text Available Weak openness and almost openness for arbitrary functions between topological spaces are defined as duals to the weak continuity of Levine and the almost continuity of Husain respectively. Independence of these two openness conditions is noted and comparison is made between these and the almost openness of Singal and Singal. Some results dual to those known for weak continuity and almost continuity are obtained. Nearly almost openness is defined and used to obtain an improved link from weak continuity to almost continuity.
Weak measurements and quantum weak values for NOON states
Rosales-Zárate, L.; Opanchuk, B.; Reid, M. D.
2018-03-01
Quantum weak values arise when the mean outcome of a weak measurement made on certain preselected and postselected quantum systems goes beyond the eigenvalue range for a quantum observable. Here, we propose how to determine quantum weak values for superpositions of states with a macroscopically or mesoscopically distinct mode number, that might be realized as two-mode Bose-Einstein condensate or photonic NOON states. Specifically, we give a model for a weak measurement of the Schwinger spin of a two-mode NOON state, for arbitrary N . The weak measurement arises from a nondestructive measurement of the two-mode occupation number difference, which for atomic NOON states might be realized via phase contrast imaging and the ac Stark effect using an optical meter prepared in a coherent state. The meter-system coupling results in an entangled cat-state. By subsequently evolving the system under the action of a nonlinear Josephson Hamiltonian, we show how postselection leads to quantum weak values, for arbitrary N . Since the weak measurement can be shown to be minimally invasive, the weak values provide a useful strategy for a Leggett-Garg test of N -scopic realism.
Electron scattering by nuclei and transition charge densities
International Nuclear Information System (INIS)
Gul'karov, I.S.
1988-01-01
Transition charge densities for states of electric type, for nuclei with A≤40--50 as obtained from data on inelastic electron scattering, are studied. The formalism of electroexcitation of nuclei is considered, together with various models (macroscopic and microscopic) used to calculate form factors, transition charge densities, and the moments of these densities: B(Eλ) and R/sub λ/ . The macroscopic models are derived microscopically, and it is shown that the model-independent sum rules lead to the same transition densities as calculations based on various hydrodynamic models. The sum rules with and without allowance for the Skyrme exchange interaction are discussed. The results of the calculations are compared with the experimental form factors of electron scattering by nuclei from 12 C to 48 Ca with excitation in them of normal-parity states with I/sup π/ = 0 + , 1 - , 2 + , 3 - , 4 + , 5 - and T = 0. The model-independent transition charge densities for the weakly collectivized excitations differ strongly from the model-dependent densities. The influence of neutrons on the transition charge densities of the nuclear isotopes 16 /sup ,/ 18 O, 32 /sup ,/ 34 S, and 40 /sup ,/ 48 Ca is considered
Curvature bound from gravitational catalysis
Gies, Holger; Martini, Riccardo
2018-04-01
We determine bounds on the curvature of local patches of spacetime from the requirement of intact long-range chiral symmetry. The bounds arise from a scale-dependent analysis of gravitational catalysis and its influence on the effective potential for the chiral order parameter, as induced by fermionic fluctuations on a curved spacetime with local hyperbolic properties. The bound is expressed in terms of the local curvature scalar measured in units of a gauge-invariant coarse-graining scale. We argue that any effective field theory of quantum gravity obeying this curvature bound is safe from chiral symmetry breaking through gravitational catalysis and thus compatible with the simultaneous existence of chiral fermions in the low-energy spectrum. With increasing number of dimensions, the curvature bound in terms of the hyperbolic scale parameter becomes stronger. Applying the curvature bound to the asymptotic safety scenario for quantum gravity in four spacetime dimensions translates into bounds on the matter content of particle physics models.
Weak interaction potentials of nucleons in the Weinberg-Salam model
International Nuclear Information System (INIS)
Lobov, G.A.
1979-01-01
Weak interaction potentials of nucleons due to the nonet vector meson exchange are obtained in the Weinberg-Salam model using the vector-meson dominance. Contribution from the hadronic neutral currents to the weak interaction potential due to the charged pion exchange is obtained. The isotopic structure of the obtained potentials, that is unambiguous in the Weinberg-Salam model, is investigated. Enhancement of the nucleon weak interaction in nuclei resulting from the hadronic neutral currents is discussed. A nuclear one-particle weak interaction potential is presented that is a result of averaging of the two-particle potential over the states of the nuclear core. An approach to the nucleon weak interaction based on the quark model, is discussed. Effects of the nucleon weak interaction in the radiative capture of a thermal neutron by a proton, are considered
Effects of QCD bound states on dark matter relic abundance
Energy Technology Data Exchange (ETDEWEB)
Liew, Seng Pei [Department of Physics, The University of Tokyo,Bunkyo-ku, Tokyo 113-0033 (Japan); Luo, Feng [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan)
2017-02-17
We study scenarios where there exists an exotic massive particle charged under QCD in the early Universe. We calculate the formation and dissociation rates of bound states formed by pairs of these particles, and apply the results in dark matter (DM) coannihilation scenarios, including also the Sommerfeld effect. We find that on top of the Sommerfeld enhancement, bound-state effects can further significantly increase the largest possible DM masses which can give the observed DM relic abundance, by ∼30–100% with respect to values obtained by considering the Sommerfeld effect only, for the color triplet or octet exotic particles we consider. In particular, it indicates that the Bino DM mass in the right-handed stop-Bino coannihilation scenario in the Minimal Supersymmetric extension of the Standard Model (MSSM) can reach ∼2.5 TeV, even though the potential between the stop and antistop prior to forming a bound state is repulsive. We also apply the bound-state effects in the calculations of relic abundance of long-lived or metastable massive colored particles, and discuss the implications on the BBN constraints and the abundance of a super-weakly interacting DM. The corrections for the bound-state effect when the exotic massive colored particles also carry electric charges, and the collider bounds are also discussed.
Combining Alphas via Bounded Regression
Directory of Open Access Journals (Sweden)
Zura Kakushadze
2015-11-01
Full Text Available We give an explicit algorithm and source code for combining alpha streams via bounded regression. In practical applications, typically, there is insufficient history to compute a sample covariance matrix (SCM for a large number of alphas. To compute alpha allocation weights, one then resorts to (weighted regression over SCM principal components. Regression often produces alpha weights with insufficient diversification and/or skewed distribution against, e.g., turnover. This can be rectified by imposing bounds on alpha weights within the regression procedure. Bounded regression can also be applied to stock and other asset portfolio construction. We discuss illustrative examples.
Improved Range Searching Lower Bounds
DEFF Research Database (Denmark)
Larsen, Kasper Green; Nguyen, Huy L.
2012-01-01
by constructing a hard input set and query set, and then invoking Chazelle and Rosenberg's [CGTA'96] general theorem on the complexity of navigation in the pointer machine. For the group model, we show that input sets and query sets that are hard for range reporting in the pointer machine (i.e. by Chazelle...... and Rosenberg's theorem), are also hard for dynamic range searching in the group model. This theorem allows us to reuse decades of research on range reporting lower bounds to immediately obtain a range of new group model lower bounds. Amongst others, this includes an improved lower bound for the fundamental...
Probing Andreev bound states in one-atom superconducting contacts
Energy Technology Data Exchange (ETDEWEB)
Pothier, Hugues; Janvier, Camille; Tosi, Leandro; Girit, Caglar; Goffman, Marcelo; Esteve, Daniel; Urbina, Cristian [Quantronics Group, SPEC, CEA-Saclay (France)
2015-07-01
Superconductors are characterized by a dissipationless current. Since the work of Josephson 50 years ago, it is known that a supercurrent can even flow through tunnel junctions between superconductors. This Josephson effect also occurs through any type of ''weak links'' between superconductors: non-superconducting materials, constrictions,.. A unified understanding of the Josephson effect has emerged from a mesoscopic description of weak links. It relies on the existence of doublets of localized states that have energies below the superconducting gap: the Andreev bound states. I will present experiments performed on the simplest conductor possible, a single-atom contact between superconductors, that illustrate these concepts. The most recent work demonstrates time-domain manipulation of quantum superpositions of Andreev bound states.
Weak Interaction processes in core-collapse supernova
International Nuclear Information System (INIS)
Martinez-Pinedo, Gabriel
2008-01-01
In this manuscript we review the role that weak interaction processes play in supernova. This includes electron captures and inelastic neutrino-nucleus scattering (INNS). Electron captures during the collapse occur mainly in heavy nuclei, however the proton contribution is responsible for the convergence of different models to a 'norm' stellar trajectory. Neutrino-nucleus cross sections at supernova neutrino energies can be determined from precise data on the magnetic dipole strength. The results agree well with large-scale shell-model calculations. When incorporated in core-collapse simulations INNS increases the neutrino opacities noticeably and strongly reduces the high-energy part of the supernova spectrum
Exotic light nuclei and nuclei in the lead region
International Nuclear Information System (INIS)
Poppelier, N.A.F.M.
1989-01-01
Three methods are discussed for modifying, or renormalizing, a truncated nuclear hamiltonian such that the wave functions obtained by diagonalizing this modified or effective hamiltoniandescribe the nucleus as well as possible: deriving the hamiltonian directly from a realistic nucleon-nucleon interaction between free nucleons; parametrizing the hamiltonian in terms of a number of parameters and determining these parameters from a least-squares fit of calculated properties to experimental data; approximating the nucleon-nucleon (NN) interaction between two nucleons in a nucleus by a simple analytic expression. An effective hamiltonian derived following the second method is applied in a theoretical study of exotic nuclei in the region of Z=2-9 and A=4-30 and the problem of the neutron halo in 11 Li is discussed. Results of shell-model calculations of 20i Pb and nuclei in its neighbourhood are presented in which an effective hamiltonian was employed derived with the last method. The quenching of M1 strength in 208 Pb, and the spectroscopic factors measured in proton knock-out reactions could be described quite satisfactory. Finally, a method is presented for deriving the effective hamiltonian directly from the realistic NN interaction with algebraic techniques. (H.W.). 114 refs.; 34 figs.; 12 tabs.; schemes
Interaction of antiprotons with nuclei
Czech Academy of Sciences Publication Activity Database
Hrtánková, Jaroslava; Mareš, Jiří
2016-01-01
Roč. 945, JAN (2016), s. 197-215 ISSN 0375-9474 R&D Projects: GA ČR(CZ) GA15-04301S Institutional support: RVO:61389005 Keywords : antiproton-nucleus interaction * antiproton annihilation * antiproton nuclear bound states Subject RIV: BE - Theoretical Physics Impact factor: 1.916, year: 2016
Self-bound droplets of a dilute magnetic quantum liquid
Schmitt, Matthias; Wenzel, Matthias; Böttcher, Fabian; Ferrier-Barbut, Igor; Pfau, Tilman
2016-11-01
Self-bound many-body systems are formed through a balance of attractive and repulsive forces and occur in many physical scenarios. Liquid droplets are an example of a self-bound system, formed by a balance of the mutual attractive and repulsive forces that derive from different components of the inter-particle potential. It has been suggested that self-bound ensembles of ultracold atoms should exist for atom number densities that are 108 times lower than in a helium droplet, which is formed from a dense quantum liquid. However, such ensembles have been elusive up to now because they require forces other than the usual zero-range contact interaction, which is either attractive or repulsive but never both. On the basis of the recent finding that an unstable bosonic dipolar gas can be stabilized by a repulsive many-body term, it was predicted that three-dimensional self-bound quantum droplets of magnetic atoms should exist. Here we report the observation of such droplets in a trap-free levitation field. We find that this dilute magnetic quantum liquid requires a minimum, critical number of atoms, below which the liquid evaporates into an expanding gas as a result of the quantum pressure of the individual constituents. Consequently, around this critical atom number we observe an interaction-driven phase transition between a gas and a self-bound liquid in the quantum degenerate regime with ultracold atoms. These droplets are the dilute counterpart of strongly correlated self-bound systems such as atomic nuclei and helium droplets.
Isospin mixing in light nuclei
International Nuclear Information System (INIS)
Ludwig, E.J.; Clegg, T.B.; Fauber, R.E.; Karwowski, H.J.; Mooney, T.M.; Thompson, W.J.
1985-01-01
This program has provided accurate measurements of isospin mixing (ΔT = 1,2) in proton elastic scattering on even-even target nuclei up to A = 40. In order to improve experimental results and to test the hypothesis that isospin mixing is dominated by mixing in the target ground state (as opposed to mixing in the compound system) the authors have undertaken to (1) extend the proton scattering results to additional T = 3/2 states in certain compound systems and (2) examine processes which can proceed by only isotensor mixing (ΔT = 2) in order to isolate the effects of that contribution
Nucleon transfer between heavy nuclei
International Nuclear Information System (INIS)
Von Oertzen, W.
1984-02-01
Nucleon transfer reactions between heavy nuclei are characterized by the classical behaviour of the scattering orbits. Thus semiclassical concepts are well suited for the description of these reactions. In the present contribution the characteristics of single and multinucleon transfer reactions at energies below and above the Coulomb barrier are shown for systems like Sn+Sn, Xe+U and Ni+Pb. The role of the pairing interaction in the transfer of nucleon pairs is illustrated. For strong transitions the coupling of channels and the absorption into more complicated channels is taken into account in a coupled channels calculation
Microscopic structure for light nuclei
International Nuclear Information System (INIS)
Sharma, V.K.
1995-01-01
The microscopic structure for light nuclei e.g. 4 He, 7 Li and 8 Be is considered in the frame work of the generator coordinate method (GCM). The physical interpretation of our GCM is also discussed. The GC amplitudes are used to calculate the various properties like charge and magnetic RMS radii, form factors, electromagnetic moments, astrophysical S-factor, Bremsstrahlung weighted cross sections, relative wavefunctions and vertex functions etc. All the calculated quantities agree well with the values determined experimentally. (author). 30 refs., 10 figs., 2 tabs
Microscopic properties of superdeformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Karlsson, Lennart B
1999-04-01
Many high spin rotational bands in superdeformed nuclei have been found in the A 140 - 150 region, but so far no linking transitions to known normal-deformed states have been found in these nuclei. Therefore, configuration and spin assignments have to be based on indirect spectroscopic information. Identical bands were first discovered in this region of superdeformed states. At present, some identical bands have also been found at normal deformation, but such bands are more common at superdeformation. Recently lifetime measurements have given relative quadrupole moments with high accuracy. Spectroscopic quantities are calculated using the configuration constrained cranked Nilsson-Strutinsky model with the modified oscillator potential. In a statistical study the occurrence of identical bands is tested. Comparing superdeformed and normal deformed nuclei, the higher possibility for identical bands at superdeformation is understood from calculated reduced widths of the E{sub {gamma}} and J{sup (2)} distributions. The importance of high-N orbitals for identical bands is also discussed. Additivity of electric quadrupole moment contributions in the superdeformed A - 150 region is discussed with the nucleus {sup 152}Dy as a `core`. In analytic harmonic oscillator calculations, the effective electric quadrupole moment q{sub eff}, i.e. the change in the total quadrupole moment caused by the added particle, is expressed as a simple function of the single-particle mass, quadrupole moment q{sub {nu}}. Also in realistic calculations, simple relations between q{sub eff} and q{sub {nu}} can be used to estimate the total electric quadrupole moment, e.g. for the nucleus {sup 142}Sm, by adding the effect of 10 holes, to the total electric quadrupole moment of {sup 152}Dy. Furthermore, tools are given for estimating the quadrupole moment for possible configurations in the superdeformed A - 150 region. For the superdeformed region around {sup 143}Eu, configuration and spin assignments
Weak decays of stable particles
International Nuclear Information System (INIS)
Brown, R.M.
1988-09-01
In this article we review recent advances in the field of weak decays and consider their implications for quantum chromodynamics (the theory of strong interactions) and electroweak theory (the combined theory of electromagnetic and weak interactions), which together form the ''Standard Model'' of elementary particles. (author)
The Navier-Stokes equations on a bounded domain
International Nuclear Information System (INIS)
Scheffer, V.
1980-01-01
Suppose U is an open bounded subset of 3-space such that the boundary of U has Lebesgue measure zero. Then for any initial condition with finite kinetic energy we can find a global (i.e. for all time) weak solution u to the time dependent Navier-Stokes equations of incompressible fluid flow in U such that the curl of u is continuous outside a locally closed set whose 5/3 dimensional Hausdorff measure is finite. (orig.)
Bound nucleon structure function in the picture of relativistic constituent quarks
International Nuclear Information System (INIS)
Grigoryan, L.A.; Shakhbazyan, V.A.
1987-01-01
The structure function F 2N of nucleons in the deuterium, carbon and iron nuclei is calculated as a function of Q 2 in two approaches: taking into account the nucleon swelling in nuclei due to the partial deconfinement of quarks in nuclear medium; in the conventional approach of nuclear physics, taking into account the getting off the mass shell of the bound nucleon and Fermi motion in nucleons. It is shown that the conventional approach of nuclear physics does not explain the EMC effect in the region of small x
The Biological Effects of Weak Electromagnetic Fields
International Nuclear Information System (INIS)
Algattawi, A.; Elshyrih, H.
2010-01-01
Many studies investigated that weak electromagnetic fields remove calcium ions bound to the membranes of living cells, making them more likely to tear,. There is an enzyme that destroys DNA this enzyme leaking through the membranes of lysosomes explains the fragmentation of DNA. This case was seen in cells exposed to mobile phone signals. When this occurs in the germ line it reduces fertility and predicts genetic damage in future generations. Although leakage of calcium ions into the cytosol (the main part of the cell) accelerates the growth, but it also promotes the growth of tumors. Leakage of calcium ions into neurons (brain cells) makes nerve impulses accounting for pain and other neurological symptoms in electro sensitive. It also reduces the signal to noise ratio of the brain making it less likely to respond. This may be partially responsible for the increased accident rate of drivers using mobile phones. More details for the molecular mechanisms to explain characteristics of electromagnetic exposure are needed, e.g. I) why weak fields are more effective than strong ones, II) why some frequencies such as 16 Hz are especially potent and III) why pulsed fields do more damage
Electromagnetic current in weak interactions
International Nuclear Information System (INIS)
Ma, E.
1983-01-01
In gauge models which unify weak and electromagnetic interactions, the weak neutral-current interaction also involves the electromagnetic current. The exact nature of such a component can be explored using e + e - experimental data. In recent years, the existence of a new component of the weak interaction has become firmly established, i.e., the neutral-current interaction. As such, it competes with the electromagnetic interaction whenever the particles involved are also charged, but at a very much lower rate because its effective strength is so small. Hence neutrino processes are best for the detection of the neutral-current interaction. However, in any gauge model which unifies weak and electromagnetic interactions, the weak neutral-current interaction also involves the electromagnetic current
Weak values in collision theory
de Castro, Leonardo Andreta; Brasil, Carlos Alexandre; Napolitano, Reginaldo de Jesus
2018-05-01
Weak measurements have an increasing number of applications in contemporary quantum mechanics. They were originally described as a weak interaction that slightly entangled the translational degrees of freedom of a particle to its spin, yielding surprising results after post-selection. That description often ignores the kinetic energy of the particle and its movement in three dimensions. Here, we include these elements and re-obtain the weak values within the context of collision theory by two different approaches, and prove that the results are compatible with each other and with the results from the traditional approach. To provide a more complete description, we generalize weak values into weak tensors and use them to provide a more realistic description of the Stern-Gerlach apparatus.
Schulz, Marc Daniel; Dusuel, Sébastien; Vidal, Julien
2016-11-01
We discuss the emergence of bound states in the low-energy spectrum of the string-net Hamiltonian in the presence of a string tension. In the ladder geometry, we show that a single bound state arises either for a finite tension or in the zero-tension limit depending on the theory considered. In the latter case, we perturbatively compute the binding energy as a function of the total quantum dimension. We also address this issue in the honeycomb lattice where the number of bound states in the topological phase depends on the total quantum dimension. Finally, the internal structure of these bound states is analyzed in the zero-tension limit.
On functions of bounded semivariation
Czech Academy of Sciences Publication Activity Database
Monteiro, Giselle Antunes
2015-01-01
Roč. 40, č. 2 (2015), s. 233-276 ISSN 0147-1937 Institutional support: RVO:67985840 Keywords : semivariation * functions of bounded variation * regulated functions Subject RIV: BA - General Mathematics http://projecteuclid.org/euclid.rae/1491271216
Computational Lower Bounds Using Diagonalization
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 7. Computational Lower Bounds Using Diagonalization - Languages, Turing Machines and Complexity Classes. M V Panduranga Rao. General Article Volume 14 Issue 7 July 2009 pp 682-690 ...
Exotic nuclei: another aspect of nuclear structure
International Nuclear Information System (INIS)
Dobaczewski, J.; Blumenfeld, Y.; Flocard, H.; Garcia Borge, M.J.; Nowacki, F.; Rombouts, S.; Theisen, Ch.; Marques, F.M.; Lacroix, D.; Dessagne, P.; Gaeggeler, H.
2002-01-01
This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements
On the distribution of quarks in nuclei
International Nuclear Information System (INIS)
Baldin, A.M.; Panebrattsev, V.S.; Stavinskij, V.S.
1984-01-01
On the basis of the data on cumulative proton, deuteron and nuclear fragment production in hadr on-nucleon reactions and deep inelastic muon-nucleon scattering quark distributions in light, intemediate and heavy nuclei have been investigated. Conditions of limiting fragmentation of hadrons and nuclei in the studied processes have been investigated to obtain quark-parton structure functions (Gs 2 ) of the studied hadrons or nuclei. Invariant differential cross sections of π + , π - , K + meson production on aluminium, deuterium and lead nuclei and their dependence on scale variable at the transverse momentum value Psub(T) approximately 0 have been obtained. Properties of structure functions G 2 and behaviour of different nuclei differential cross sections of limiting fragmentation have been investigated. It is concluded that considered regularities testify to the presence of multiquark states in nuclei, different by its structure from nUcleons
Barriers in the energy of deformed nuclei
Directory of Open Access Journals (Sweden)
V. Yu. Denisov
2014-06-01
Full Text Available Interaction energy between two nuclei considering to their deformations is studied. Coulomb and nuclear in-teraction energies, as well as the deformation energies of both nuclei, are taken into account at evaluation of the interaction energy. It is shown that the barrier related to the interaction energy of two nuclei depends on the de-formations and the height of the minimal barrier is evaluated. It is obtained that the heavier nucleus-nucleus sys-tems have large deformation values at the lowest barrier. The difference between the barrier between spherical nuclei and the lowest barrier between deformed nuclei increases with the mass and the charge of the interacting nuclei.
Evolution of collectivity in neutron-rich nuclei in the 132Sn region
International Nuclear Information System (INIS)
Kshetri, Ritesh; Sarkar, M. Saha; Sarkar, S.
2006-01-01
Motivated by the observed regularity in the energy spectra and the structure of the shell model wave functions for the levels of 137 Te and 137 I, a few weakly and moderately deformed neutron-rich odd-A nuclei above the doubly magic nucleus 132 Sn were studied using the particle rotor model (PRM). The calculated energy spectra and branching ratios agree reasonably well with the most recent experimental data. In a few cases ambiguity in level ordering was resolved and spin-parities were assigned to the levels. Observed octupole correlation in some of these nuclei is discussed in the light of the present results
Study of subshell gap around N = 70 for neutron-rich nuclei
International Nuclear Information System (INIS)
Hemalatha, M.
2011-01-01
The study and search for new regions of shell closure for nuclei away from stability is a topic of current interest both experimentally and theoretically. There have been few studies predicting a weak spherical subshell gap of 110 Zr (N = 70), for example. This is supported by a recent study indicating that the spherical N = 70 shell gap may not have a large effect at N = 68 for Zr isotopes. It would be, therefore, interesting to know whether there is a subshell closure at N = 70 in the neutron rich region and also for the very neutron-rich nuclei, 110 Zr
Energy Technology Data Exchange (ETDEWEB)
Martino, J [Subatech, Ecole des Mines de Nantes, 44 - Nantes (France); Frere, J M; Naviliat-Cuncic, O; Volpe, C; Marteau, J; Lhuillier, D; Vignaud, D; Legac, R; Marteau, J; Legac, R
2003-07-01
This document gathers the lectures made at the Joliot-Curie international summer school in 2003 whose theme, that year, was the relationship between weak interaction and nucleus. There were 8 contributions whose titles are: 1) before the standard model: from beta decay to neutral currents; 2) the electro-weak theory and beyond; 3) testing of the standard model at low energies; 4) description of weak processes in nuclei; 5) 20.000 tonnes underground, an approach to the neutrino-nucleus interaction; 6) parity violation from atom to nucleon; 7) how neutrinos got their masses; and 8) CP symmetry.
Fragmentation and Multifragmentation of 10.6 A GeV Gold Nuclei
Adamovich, M I
1999-01-01
We present the results of a study performed on the interactions of 10.6A GeV gold nuclei in nuclear emulsions. In a minimum bias sample of 1311 interac- tions, 5260 helium nuclei and 2622 heavy fragments were observed as Au projec- tile fragments. The experimental data are analyzed with particular emphasis of target separation interactions in emulsions and study of criticalexponents. Multiplicity distributions of the fast-moving projectile fragments are inves- tigated. Charged fragment moments, conditional moments as well as two and three -body asymmetries of the fast moving projectile particles are determined in terms of the total charge remaining bound in the multiply charged projectile fragments. Some differences in the average yields of helium nuclei and heavier fragments are observed, which may be attributed to a target effect. However, two and three-body asymmetries and conditional moments indicate that the breakup mechanism of the projectile seems to be independent of target mass. We looked for evidenc...
Dynamical and luminosity evolution of active galactic nuclei - Models with a mass spectrum
International Nuclear Information System (INIS)
Murphy, B.W.; Cohn, H.N.; Durisen, R.H.
1991-01-01
A multimass energy-space Fokker-Planck code is used to follow the dynamical and luminosity evolution of an AGN model that consists of a dense stellar system surrounding a massive black hole. It is found that stellar evolution and tidal disruption are the predominant mass-loss mechanisms for low-density nuclei, whereas physical collisions dominate in high-density nuclei. For initial central densities greater than 10 million solar masses/cu pc the core of the stellar system contacts due to the removal of kinetic energy by collisions, whereas for densities less than this the core of the stellar system expands due to heating that results from the settling of a small population of stars into orbits tightly bound to the black hole. These mechanisms produce differing power-law slopes in the resulting stellar density cusp surrounding the black hole, -7/4 and -1/2 for low- and high-density nuclei, respectively. 60 refs
Impact of electron-captures on nuclei near N = 50 on core-collapse supernovae
Titus, R.; Sullivan, C.; Zegers, R. G. T.; Brown, B. A.; Gao, B.
2018-01-01
The sensitivity of the late stages of stellar core collapse to electron-capture rates on nuclei is investigated, with a focus on electron-capture rates on 74 nuclei with neutron number close to 50, just above doubly magic 78Ni. It is demonstrated that variations in key characteristics of the evolution, such as the lepton fraction, electron fraction, entropy, stellar density, and in-fall velocity are about 50% due to uncertainties in the electron-capture rates on nuclei in this region, although thousands of nuclei are included in the simulations. The present electron-capture rate estimates used for the nuclei in this high-sensitivity region of the chart of isotopes are primarily based on a simple approximation, and it is shown that the estimated rates are likely too high, by an order of magnitude or more. Electron-capture rates based on Gamow-Teller strength distributions calculated in microscopic theoretical models will be required to obtain better estimates. Gamow-Teller distributions extracted from charge-exchange experiments performed at intermediate energies serve to guide the development and benchmark the models. A previously compiled weak-rate library that is used in the astrophysical simulations was updated as part of the work presented here, by adding additional rate tables for nuclei near stability for mass numbers between 60 and 110.
Bounds on dark matter interactions with electroweak gauge bosons
Energy Technology Data Exchange (ETDEWEB)
Cotta, R. C.; Hewett, J. L.; Le, M. -P.; Rizzo, T. G.
2013-12-01
We investigate scenarios in which dark matter interacts with the Standard Model primarily through electroweak gauge bosons. We employ an effective field theory framework wherein the Standard Model and the dark matter particle are the only light states in order to derive model-independent bounds. Bounds on such interactions are derived from dark matter production by weak boson fusion at the LHC, indirect detection searches for the products of dark matter annihilation and from the measured invisible width of the Z^{ 0} . We find that limits on the UV scale, Λ , reach weak scale values for most operators and values of the dark matter mass, thus probing the most natural scenarios in the weakly interacting massive particle dark matter paradigm. Our bounds suggest that light dark matter ( m_{ χ} ≲ m_{ Z} / 2 or m _{χ} ≲ 100 – 200 GeV , depending on the operator) cannot interact only with the electroweak gauge bosons of the Standard Model, but rather requires additional operator contributions or dark sector structure to avoid overclosing the Universe.
Laser method of free atom nuclei orientation
International Nuclear Information System (INIS)
Barabanov, A.L.
1987-01-01
Orientation process of free atom (atoms in beams) nuclei, scattering quanta of circularly polarized laser radiation is considered. A method for the evaluation of nuclei orientation parameters is developed. It is shown that in the process of pumping between the ground and first excited atomic states with electron shell spins J 1 and J 2 , so that J 2 = J 1 + 1, a complete orientation of nuclei can be attained
Are there multiquark bags in nuclei
International Nuclear Information System (INIS)
Kondratyuk, L.A.; Scmatkov, M.Zh.
1983-01-01
Arguments are presented favouring the idea that multiquark bags do eXist in nuclei. Such hypothesis makes possible to reveal the relationship among three different scopes of phenomena: deep inelastic scattering of leptons by nUclei, large q 2 (where q 2 is a square of momentum transfer) behaviour of the form factors of light nuclei and yield of cumulative proton.s
Understanding Nuclei in the upper sd - shell
Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S.
2013-01-01
Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array...
Possible existence of backbending in actinide nuclei
International Nuclear Information System (INIS)
Dudek, J.; Nazarewicz, W.; Szymanski, Z.
1982-01-01
The possibilities for the backbending effect to occur in actinide nuclei are studied using the pairing-self-consistent independent quasiparticle method. The Hamiltonian used is that of the deformed Woods-Saxon potential plus monopole pairing term. The results of the calculations explain why there is no backbending in most actinide nuclei and simultaneously suggest that in some light neutron deficient nuclei around Th and 22 Ra a backbending effect may occur
Nuclei quadrupole coupling constants in diatomic molecule
International Nuclear Information System (INIS)
Ivanov, A.I.; Rebane, T.K.
1993-01-01
An approximate relationship between the constants of quadrupole interaction of nuclei in a two-atom molecule is found. It enabled to establish proportionality of oscillatory-rotation corrections to these constants for both nuclei in the molecule. Similar results were obtained for the factors of electrical dipole-quadrupole screening of nuclei. Applicability of these relationships is proven by the example of lithium deuteride molecule. 4 refs., 1 tab
Nuclei at the limits of particle stability
International Nuclear Information System (INIS)
Mueller, A.C.
1993-01-01
The properties and synthesis of nuclei at the limits of particle stability are reviewed. Nuclear reactions were induced and studied by means of the 'exotic' nuclear beams, i.e. beams of radioactive drip-line nuclei. The beams are mostly generated in heavy-ion projectile fragmentation. The cases of both neutron-rich and proton-rich nuclei are discussed. (K.A.) 270 refs.; 13 figs.; 1 tab
Mass-23 nuclei in astrophysics
International Nuclear Information System (INIS)
Fraser, P R; Amos, K; Van der Kniff, D; Canton, L; Karataglidis, S; Svenne, J P
2015-01-01
The formation of mass-23 nuclei by radiative capture is of great interest in astrophysics. A topical problem associated with these isobars is the so-called 22 Na puzzle of ONe white dwarf novae, where the abundance of 22 Na observed is not as is predicted by current stellar models, indicating there is more to learn about how the distribution of elements in the universe occurred. Another concerns unexplained variations in elements abundance on the surface of aging red giant stars. One method for theoretically studying nuclear scattering is the Multi-Channel Algebraic Scattering (MCAS) formalism. Studies to date have used a simple collective-rotor prescription to model the target states which couple to projectile nucleons. While, in general, the target states considered all belong to the ground state rotor band, for some systems it is necessary to include coupling to states outside of this band. Herein we discuss an extension of MCAS to allow coupling of different strengths between such states and the ground state band. This consideration is essential when studying the scattering of neutrons from 22 Ne, a necessary step in studying the mass-23 nuclei mentioned above. (paper)
Hartman effect and weak measurements that are not really weak
International Nuclear Information System (INIS)
Sokolovski, D.; Akhmatskaya, E.
2011-01-01
We show that in wave packet tunneling, localization of the transmitted particle amounts to a quantum measurement of the delay it experiences in the barrier. With no external degree of freedom involved, the envelope of the wave packet plays the role of the initial pointer state. Under tunneling conditions such ''self-measurement'' is necessarily weak, and the Hartman effect just reflects the general tendency of weak values to diverge, as postselection in the final state becomes improbable. We also demonstrate that it is a good precision, or a 'not really weak' quantum measurement: no matter how wide the barrier d, it is possible to transmit a wave packet with a width σ small compared to the observed advancement. As is the case with all weak measurements, the probability of transmission rapidly decreases with the ratio σ/d.
Expected impact from weak reactions with light nuclei in corecollapse supernova simulations
Directory of Open Access Journals (Sweden)
Fischer T.
2016-01-01
Full Text Available We study the role of light nuclear clusters in simulations of core-collapse supernovae. Expressions for the reaction rates are developed for a large selection of charged current absorption and scattering processes with light clusters. Medium modifications are taken into account at the mean-field level. We explore the possible impact on the supernova dynamics and the neutrino signal during the mass accretion phase prior to the possible explosion onset as well as during the subsequent protoneutron star deleptnoization after the explosion onset has been launched.
International Nuclear Information System (INIS)
Grechukhin, D.P.; Soldatov, A.A.
1977-01-01
The intensity of the satellite lines of the 2s1/2→1s1/2 radiative transition in a mesic atom due to configurational interaction between the meson and shell electrons of the mesic atom is estimated. The intensity of these satellite lines is shown to be about six orders of magnitude greater than the intensity of the emission in the 2s1/2→1s1/2 meson transition. Configurational interaction between the meson and conductivity band electrons in metals precludes the usage of a metal target for stopping the mesons in the experiment. Estimates show that for mesic atoms produced in a gas the Stark effect of the electric dipole field induced in collisions between atoms of the medium and a mesic atom (Z>=2) stripped of electrons significantly restricts the density of the medium from above such that the density is 14 at/cm 3 ; in the case of the Stark effect of the intra-atomic field and collisions between a μH atom and atoms of the medium the corresponding value is 11 at/cm 3
Guarnieri, C; Flamigni, F; Caldarera, C M
1980-01-01
An alpha-tocopherol-binding macromolecule was isolated from the heart cytosol of rabbits fed for 1 month with an alpha-tocopherol-deficient diet. The amount of [3H]-tocopherol bound to nuclear chromatin was increased when the alpha-tocopherol-deficient heart nuclei were incubated in the presence of [3H]tocopherol-cytosol complex. In this condition, large amounts of [3H]tocopherol were associated with a subnuclear fraction that contained non-histone acidic proteins.
The ratio method: a new way to look at halo nuclei
Directory of Open Access Journals (Sweden)
Capel P.
2014-03-01
Full Text Available A new reaction observable is presented to study exotic loosely-bound structures, such as halo nuclei. It consists of the ratio of two angular distributions, e. g. one for breakup and one for elastic scattering. This ratio is nearly independent of the reaction mechanism and is very sensitive to the projectile structure. This new ratio method is illustrated on the particular case of 11Be, the archetypal one-neutron halo nucleus.
The asymptotic hadron spectrum, anti-nuclei, hyper-nuclei and quark phase
International Nuclear Information System (INIS)
Glendenning, N.K.
1978-01-01
The only hope of determining the hadronic spectrum in the high mass region is through a study of matter produced in very high energy nuclear collisions. Along the way, exotic nuclei, i.e., anti-nuclei and hyper-nuclei may be produced in appreciable numbers, and the detection of a quark phase may be possible. (orig.) [de
Gamow-Teller decay of T = 1 nuclei to odd-odd N = Z nuclei
Energy Technology Data Exchange (ETDEWEB)
Lisetskiy, A F [National Superconducting Cyclotron Laboratory, MSU, East Lansing, MI 48824 (United States); Gelberg, A [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany); Institute of Physical and Chemical Reasearch (RIKEN), Wako, 351-0198 (Japan); Brentano, P von [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany)
2005-01-01
Transition strengths of Gamow-Teller decay of T{sub z} = {+-}1 nuclei to N = Z odd-odd nuclei have been calculated in a two-nucleon approximation for spherical and deformed nuclei. The results obtained for the latter are quite close to the values obtained by full-space shell-model calculations and to the experiment.
On the scarcity of weak coupling in the string landscape
Halverson, James; Long, Cody; Sung, Benjamin
2018-02-01
We study the geometric requirements on a threefold base for the corresponding F-theory compactification to admit a weakly-coupled type IIB limit. We examine both the standard Sen limit and a more restrictive limit, and determine conditions sufficient for their non-existence for both toric bases and more general algebraic bases. In a large ensemble of geometries generated by base changing resolutions we derive an upper bound on the frequency with which a weak-coupling limit may occur, and find that such limits are extremely rare. Our results sharply quantify the widely held notion that the vast number of weakly-coupled IIB vacua is but a tiny fraction of the landscape.
Implications of neutrino masses and mixing for weak processes
International Nuclear Information System (INIS)
Shrock, R.E.
1981-01-01
A general theory is presented of weak processes involving neutrinos which consistently incorporates the possibility of nonzero neutrino masses and associated lepton mixing. The theory leads to new tests for and bounds on such masses and mixing. These tests make use of (π,K)/sub l2/ decay, nuclear β decay, and μ and tau decays, among others. New experiments at SIN and KEK to apply the tests are mentioned. Further, some implications are discussed for (1) the analysis of the spectral parameters in leptonic decays to determine the Lorentz structure of the weak leptonic couplings; (2) fundamental weak interaction constants such as G/sub μ/, G/sub V/', f/sub π/, f/sub K/, V/sub uq/, q = d or s, m/sub W/, and m/sub Z/; and (3) neutrino propagation
Weak Measurement and Quantum Correlation
Indian Academy of Sciences (India)
Arun Kumar Pati
Entanglement: Two quantum systems can be in a strongly correlated state even if .... These are resources which can be used to design quantum computer, quantum ...... Weak measurements have found numerous applications starting from the ...
Weakly infinite-dimensional spaces
International Nuclear Information System (INIS)
Fedorchuk, Vitalii V
2007-01-01
In this survey article two new classes of spaces are considered: m-C-spaces and w-m-C-spaces, m=2,3,...,∞. They are intermediate between the class of weakly infinite-dimensional spaces in the Alexandroff sense and the class of C-spaces. The classes of 2-C-spaces and w-2-C-spaces coincide with the class of weakly infinite-dimensional spaces, while the compact ∞-C-spaces are exactly the C-compact spaces of Haver. The main results of the theory of weakly infinite-dimensional spaces, including classification via transfinite Lebesgue dimensions and Luzin-Sierpinsky indices, extend to these new classes of spaces. Weak m-C-spaces are characterised by means of essential maps to Henderson's m-compacta. The existence of hereditarily m-strongly infinite-dimensional spaces is proved.
Weak interactions and presupernova evolution
International Nuclear Information System (INIS)
Aufderheide, M.B.; State Univ. of New York
1991-01-01
The role of weak interactions, particularly electron capture and β - decay, in presupernova evolution is discussed. The present uncertainty in these rates is examined and the possibility of improving the situation is addressed. 12 refs., 4 figs
Weak Deeply Virtual Compton Scattering
International Nuclear Information System (INIS)
Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin
2006-01-01
We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities
Weakly compact operators and interpolation
Maligranda, Lech
1992-01-01
The class of weakly compact operators is, as well as the class of compact operators, a fundamental operator ideal. They were investigated strongly in the last twenty years. In this survey, we have collected and ordered some of this (partly very new) knowledge. We have also included some comments, remarks and examples. The class of weakly compact operators is, as well as the class of compact operators, a fundamental operator ideal. They were investigated strongly in the last twenty years. I...
Composite hadrons and relativistic nuclei
International Nuclear Information System (INIS)
Blankenbecler, R.
1978-01-01
Lectures are presented describing a model of hadronic scattering at large momentum transfer, either transverse or longitudinal. This model emphasizes in this regime the importance of forces involving the interchange of constituents of the hadrons, hence its name, the constituent interchange model CIM. The CIM is a rearrangement of standard perturbation theory to take into account the fact that the binding force is very strong in color singlet states (singlet dominance). The hard scattering expansion, incoherence problems, nuclear wave functions and counting rules, interaction between nuclei, pion and proton yields and form factors, structure functions and nonscaling, massive lepton pairs, hadrons at large transverse momentum, and quark-quark scattering are treated. 49 references
International Nuclear Information System (INIS)
Soloviev, V.G.
1995-01-01
Order and chaos and order-to-chaos transition are treated in terms of nuclear wave functions. A quasiparticle-phonon interaction is responsible for the fragmentation of one- and many-quasiparticle and phonon states and for the mixing of closely spaced states. Complete damping of one-quasiparticle states cannot be considered as a transition to chaos due to large many-quasiparticle or quasiparticle-phonon terms in their wave functions. An experimental investigation of the strength distribution of many-quasiparticle and quasiparticle-phonon states should uncover a new region of a regularity in nuclei at intermediate excitation energy. A chaotic behaviour of nuclear states can be shifted to higher excitation energies. ((orig.))
Relativistic description of atomic nuclei
International Nuclear Information System (INIS)
Krutov, V.A.
1985-01-01
Papers on the relativistic description of nuclei are reviewed. The Brown and Rho ''small'' bag'' model is accepted for hardrons. Meson exchange potentials of the nucleon-nucleon interaction have been considered. Then the transition from a system of two interacting nucleons has been performed to the relativistic nucleus description as a multinucleon system on the basis of OBEP (one-boson exchange potential). The proboem of OPEP (one-pion-exchange potential) inclusion to a relativistic scheme is discussed. Simplicity of calculations and attractiveness of the Walecka model for specific computations and calculations was noted. The relativistic model of nucleons interacting through ''effective'' scalar and vector boson fields was used in the Walacka model for describing neutronaand nuclear mater matters
Electric quadrupole strength in nuclei
International Nuclear Information System (INIS)
Kirson, M.W.
1979-01-01
Isoscalar electric quadrupole strength distributions in nuclei are surveyed, and it is concluded that the strength is shared, in most cases, roughly equally between low-lying transitions and the giant quadrupole state. The same is not true of the isovector case. A simple extension of the schematic model gives a remarkably successul description of the data, and emphasizes the vital importance of the coupling between high-lying and low-lying quadrupole modes. The standadrd simple representation of the giant quadrupole resonance as produced by operating on the nuclear ground state with the quadrupole transition operator is not applicable to the isoscalar case. It is suggested that giant resonances fall into broad classes of similar states, with considerable qualitative differences between the distinct classes. (author)
Cavitation Nuclei: Experiments and Theory
DEFF Research Database (Denmark)
Mørch, Knud Aage
2009-01-01
The Swedish astrophysicist and Nobel Prize winner Hannes Alfven said: Theories come and go - the experiment is here forever. Often a theory, which we set up to describe an observed physical phenomenon, suffers from the lack of knowledge of decisive parameters, and therefore at best the theory...... becomes insufficient. Contrary, the experiment always reveals nature itself, though at prevailing experimental conditions. With essential parameters being out of control and even maybe unidentified, apparently similar experiments may deviate way beyond our expectations. However, these discrepancies offer...... us a chance to reflect on the character of the unknown parameters. In this way non-concordant experimental results may hold the key to the development of better theories - and to new experiments for the testing of their validity. Cavitation and cavitation nuclei are phenomena of that character....
Acute muscular weakness in children
Directory of Open Access Journals (Sweden)
Ricardo Pablo Javier Erazo Torricelli
Full Text Available ABSTRACT Acute muscle weakness in children is a pediatric emergency. During the diagnostic approach, it is crucial to obtain a detailed case history, including: onset of weakness, history of associated febrile states, ingestion of toxic substances/toxins, immunizations, and family history. Neurological examination must be meticulous as well. In this review, we describe the most common diseases related to acute muscle weakness, grouped into the site of origin (from the upper motor neuron to the motor unit. Early detection of hyperCKemia may lead to a myositis diagnosis, and hypokalemia points to the diagnosis of periodic paralysis. Ophthalmoparesis, ptosis and bulbar signs are suggestive of myasthenia gravis or botulism. Distal weakness and hyporeflexia are clinical features of Guillain-Barré syndrome, the most frequent cause of acute muscle weakness. If all studies are normal, a psychogenic cause should be considered. Finding the etiology of acute muscle weakness is essential to execute treatment in a timely manner, improving the prognosis of affected children.
Femtometer toroidal structures in nuclei
International Nuclear Information System (INIS)
Forest, J.L.; Pandharipande, V.R.; Pieper, S.C.; Wiringa, R.B.; Schiavilla, R.; Arriaga, A.
1996-01-01
The two-nucleon density distributions in states with isospin T=0, spin S=1, and projection M S =0 and ±1 are studied in 2 H, 3,4 He, 6,7 Li, and 16 O. The equidensity surfaces for M S =0 distributions are found to be toroidal in shape, while those of M S =±1 have dumbbell shapes at large density. The dumbbell shapes are generated by rotating tori. The toroidal shapes indicate that the tensor correlations have near maximal strength at r 3 He, 4 He, and 6 Li. The toroidal distribution has a maximum-density diameter of ∼1 fm and a half-maximum density thickness of ∼0.9 fm. Many realistic models of nuclear forces predict these values, which are supported by the observed electromagnetic form factors of the deuteron, and also predicted by classical Skyrme effective Lagrangians, related to QCD in the limit of infinite colors. Due to the rather small size of this structure, it could have a revealing relation to certain aspects of QCD. Experiments to probe this structure and its effects in nuclei are suggested. Pair distribution functions in other T,S channels are also discussed; those in T,S=1,1 have anisotropies expected from one-pion-exchange interactions. The tensor correlations in T,S=0,1 states are found to deplete the number of T,S=1,0 pairs in nuclei and cause a reduction in nuclear binding energies via many-body effects. copyright 1996 The American Physical Society
Mean-field models and exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Bender, M; Buervenich, T; Maruhn, J A; Greiner, W [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); Rutz, K [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Reinhard, P G [Inst. fuer Theoretische Physik, Univ. Erlangen (Germany)
1998-06-01
We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
High-spin excitations of atomic nuclei
International Nuclear Information System (INIS)
Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing
2004-01-01
The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)
Microscopic Cluster Theory for Exotic Nuclei
International Nuclear Information System (INIS)
Tomaselli, M; Kuehl, T; Ursescu, D; Fritzsche, S
2006-01-01
For a better understanding of the dynamics of complex exotic nuclei it is of crucial importance to develop a practical microscopic theory easy to be applied to a wide range of masses. In this paper we propose to calculate the structure of neutron-rich nuclei within a dynamic model based on the EoM theory
Reentrainment of radioactive nuclei from filters
International Nuclear Information System (INIS)
Dincklage, R.-D. von
1982-01-01
The possible relevance of atomic phenomena for the reentrainment of radioactive nuclei is discussed. The considerations are based on the coulombic fragmentation mechanism. Nuclei of potential interest in reprocessing technology are identified. Future experiments have been shown to be of definite need in this field. (author)
Thermodynamics of pairing phase transition in nuclei
International Nuclear Information System (INIS)
Karim, Afaque; Ahmad, Shakeb
2014-01-01
The pairing gaps, pairing energy, heat capacity and entropy are calculated within BCS (Bardeen- Cooper-Schrieffer) based quasi particle approach, including thermal fluctuations on pairing field within pairing model for all nuclei (light, medium, heavy and super heavy nuclei). Quasi particles approach in BCS theory was introduced and reformulated to study various properties. For thermodynamic behavior of nuclei at finite temperatures, the anomalous averages of creation and annihilation operators are introduced. It is solved self consistently at finite temperatures to obtain BCS Hamiltonian. After doing unitary transformation, we obtained the Hamiltonian in the diagonal form. Thus, one gets temperature dependence gap parameter and pairing energy for nuclei. Moreover, the energy at finite temperatures is the sum of the condensation energy and the thermal energy of fermionic quasi particles. With the help of BCS Hamiltonian, specific heat, entropy and free energy are calculated for different nuclei. In this paper the gap parameter occupation number and pairing energy as a function of temperature which is important for all the light, medium, heavy and super heavy nuclei is calculated. Moreover, the various thermo dynamical quantities like specific heat, entropy and free energy is also obtained for different nuclei. Thus, the thermodynamics of pairing phase transition in nuclei is studied
Mean-field models and exotic nuclei
International Nuclear Information System (INIS)
Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W.; Rutz, K.; Reinhard, P.G.
1998-01-01
We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
Static and dynamical properties of hot nuclei
International Nuclear Information System (INIS)
Suraud, E.
1990-01-01
We briefly review our understanding of the formation of excited/hot nuclei in heavy-ion collisions at some tens of MeV/A. We recall the major theoretical frameworks used for describing as well the entrance channel of the reaction as the structure properties of hot nuclei. We finally focus on multifragmentation within insisting upon the theoretical challenge it does represent
Masses of nuclei close to the dripline
International Nuclear Information System (INIS)
Herfurth, F.; Blaum, K.; Audi, G.; Lunney, D.; Beck, D.; Kluge, H.J.; Rodriguez, D.; Sikler, G.; Weber, C.; Bollen, G.; Schwarz, S.; Kellerbauer, A.
2003-01-01
Mass measurements of radioactive nuclides are one of the cornerstones of our understanding of the nucleus. The Penning trap spectrometer ISOLTRAP performs direct mass measurements far away from the valley of stability, as well as high-precision measurements of key nuclei to anchor long decay chains. Both schemes provide valuable information on the dripline itself and on nuclei in its close vicinity. (orig.)
Quasars, Seyfert galaxies and active galactic nuclei
International Nuclear Information System (INIS)
Osterbrock, D.E.
1987-01-01
This chapter is devoted to the spectroscopic methods for analyzing the observed plasma in the nuclei of quasars, Seyfert galazies, and active galactic nuclei. Both the narrow-line region and the broad-line region are discussed. Physical models are presented
Single Particle Entropy in Heated Nuclei
International Nuclear Information System (INIS)
Guttormsen, M.; Chankova, R.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Syed, N. U. H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.
2006-01-01
The thermal motion of single particles represents the largest contribution to level density (or entropy) in atomic nuclei. The concept of single particle entropy is presented and shown to be an approximate extensive (additive) quantity for mid-shell nuclei. A few applications of single particle entropy are demonstrated
Quantum phase transitions in atomic nuclei
International Nuclear Information System (INIS)
Zamfir, N.V.
2005-01-01
Studies of quantum phase transitions in mesoscopic systems and applications to atomic nuclei are presented. Analysis in terms of the Interacting Boson Model shows that the main features persist even for moderate number of particles. Experimental evidence in rare-earth nuclei is discussed. New order and control parameters for systems with the same number of particles are proposed. (author)
Bounding the space of holographic CFTs with chaos
Energy Technology Data Exchange (ETDEWEB)
Perlmutter, Eric [Department of Physics, Princeton University,Jadwin Hall, Princeton, NJ 08544 (United States)
2016-10-13
Thermal states of quantum systems with many degrees of freedom are subject to a bound on the rate of onset of chaos, including a bound on the Lyapunov exponent, λ{sub L}≤2π/β. We harness this bound to constrain the space of putative holographic CFTs and their would-be dual theories of AdS gravity. First, by studying out-of-time-order four-point functions, we discuss how λ{sub L}=2π/β in ordinary two-dimensional holographic CFTs is related to properties of the OPE at strong coupling. We then rule out the existence of unitary, sparse two-dimensional CFTs with large central charge and a set of higher spin currents of bounded spin; this implies the inconsistency of weakly coupled AdS{sub 3} higher spin gravities without infinite towers of gauge fields, such as the SL(N) theories. This fits naturally with the structure of higher-dimensional gravity, where finite towers of higher spin fields lead to acausality. On the other hand, unitary CFTs with classical W{sub ∞}[λ] symmetry, dual to 3D Vasiliev or hs[λ] higher spin gravities, do not violate the chaos bound, instead exhibiting no chaos: λ{sub L}=0. Independently, we show that such theories violate unitarity for |λ|>2. These results encourage a tensionless string theory interpretation of the 3D Vasiliev theory.
Simulation bounds for system availability
International Nuclear Information System (INIS)
Tietjen, G.L.; Waller, R.A.
1976-01-01
System availability is a dominant factor in the practicality of nuclear power electrical generating plants. A proposed model for obtaining either lower bounds or interval estimates on availability uses observed data on ''n'' failure-to-repair cycles of the system to estimate the parameters in the time-to-failure and time-to-repair models. These estimates are then used in simulating failure/repair cycles of the system. The availability estimate is obtained for each of 5000 samples of ''n'' failure/repair cycles to form a distribution of estimates. Specific percentile points of those simulated distributions are selected as lower simulation bounds or simulation interval bounds for the system availability. The method is illustrated with operational data from two nuclear plants for which an exponential time-to-failure and a lognormal time-to-repair are assumed
High-energy photoproduction and electroproduction of π+ on nuclei
International Nuclear Information System (INIS)
Kuz'menko, V.S.; Mitrofanova, A.V.; Noga, V.I.; Ranyuk, Y.N.; Sorokin, P.V.; Telegin, Y.N.; Blomqvist, I.; Jonsson, G.G.; Freed, N.
1977-01-01
Cross sections for photoproduction and electroproduction of π + on 27 Al and 51 V leading to bound states in the daughter nuclei have been measured at Kharkov in the energy range 600--1200 MeV by use of the activation method. Careful comparison is made to other recent results obtained at intermediate and high energies. Agreement is found between the present data and results of earlier work carried out at Lund and DESY. Discrepancies between photoproduction data taken at different laboratories are attributed to differences between methods of background subtraction. Relative bremsstrahlung-induced to electron-induced yield ratios are compared with predictions based on the Dalitz-Yennie formalism for virtual-photon spectra
138th International School of Physics "Enrico Fermi" : Unfolding the Matter of Nuclei
Ricci, R A
1998-01-01
The nucleus and its constituents are a challenging problem. The lectures collected in this book present a broad and comprehensive review of the current knowledge about nuclei.They cover topics such as searching for signatures of the quarks in nuclei with electromagnetic probes and, at much higher energies, for signatures of the quark-gluon plasma in ultrarelativistic nuclear collisions. The attempts to obtain new nuclei in the laboratory are also discussed, as well as the central role played by nuclear physics in the development of weak interactions. Progress in all these areas rests on a deeper theoretical handling of the nuclear and nucleon’s structure. The latter can also be addressed by relying on numerical solutions of QCD on a discrete space-time lattice. The advancement of computational capabilities has spurred a growing interest in this approach. Finally, the book deals with different paths toward solving non-perturbative QCD.
Dominant Modes in Light Nuclei - Ab Initio View of Emergent Symmetries
International Nuclear Information System (INIS)
Draayer, J P; Dytrych, T; Launey, K D; Dreyfuss, A C; Langr, D
2015-01-01
An innovative symmetry-guided concept is discussed with a focus on emergent symmetry patterns in complex nuclei. In particular, the ab initio symmetry-adapted no-core shell model (SA-NCSM), which capitalizes on exact as well as partial symmetries that underpin the structure of nuclei, provides remarkable insight into how simple symmetry patterns emerge in the many-body nuclear dynamics from first principles. This ab initio view is complemented by a fully microscopic no-core symplectic shell-model framework (NCSpM), which, in turn, informs key features of the primary physics responsible for the emergent phenomena of large deformation and alpha-cluster substructures in studies of the challenging Hoyle state in Carbon-12 and enhanced collectivity in intermediate-mass nuclei. Furthermore, by recognizing that deformed configurations often dominate the low-energy regime, the SA-NCSM provides a strategy for determining the nature of bound states of nuclei in terms of a relatively small subspace of the symmetry-reorganized complete model space, which opens new domains of nuclei for ab initio investigations, namely, the intermediate-mass region, including isotopes of Ne, Mg, and Si
Nuclear weak interactions, supernova nucleosynthesis and neutrino oscillation
Kajino, Toshitaka
2013-07-01
We study the nuclear weak response in light-to-heavy mass nuclei and calculate neutrino-nucleus cross sections. We apply these cross sections to the explosive nucleosynthesis in core-collapse supernovae and find that several isotopes of rare elements 7Li, 11B, 138La, 180Ta and several others are predominantly produced by the neutrino-process nucleosynthesis. We discuss how to determine the suitable neutrino spectra of three different flavors and their anti-particles in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. Light-mass nuclei like 7Li and 11B, which are produced in outer He-layer, are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect, while heavy-mass nuclei like 138La, 180Ta and r-process elements, which are produced in the inner O-Ne-Mg layer or the atmosphere of proto-neutron star, are likely to be free from the MSW effect. Using such a different nature of the neutrino-process nucleosynthesis, we study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the unknown neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.
Structure and clusters of light unstable nuclei
International Nuclear Information System (INIS)
En'yo, Yoshiko
2010-01-01
As it is known, cluster structures are often observed in light nuclei. In the recent evolution of unstable nuclear research (on nuclei having unbalanced number of neutron and proton) further new types of clusters are coming to be revealed. In this report, structures of light unstable nuclei and some of the theoretical models to describe them are reviewed. The following topics are picked up. 1. Cluster structure and theoretical models, 2. Cluster structure of unstable nuclei (low excited state). 3. Cluster structure of neutron excess beryllium isotopes. 4. Cluster gas like state in C isotope. 5. Dineutron structure of He isotopes. Numbers of strange nuclear structures of light nuclei are illustrated. Antisymmetrized molecular dynamics (AMD) is the recently developed theoretical framework which has been successfully used in heavy ion reactions and nuclear structure studies. Successful application of AMD to the isotopes of Be, B and C are illustrated. (S. Funahashi)
Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons
Energy Technology Data Exchange (ETDEWEB)
Bodek, Arie [Univ. of Rochester, NY (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-08-01
We present preliminary results on an experimental study of the nuclear modification of the longitudinal ($\\sigma_L$) and transverse ($\\sigma_T$) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= $\\sigma_L / \\sigma_T$ for nuclei ($R_A$) and for deuterium ($R_D$) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, $R_A< R_D$.
Relativistic bound state wave functions
International Nuclear Information System (INIS)
Micu, L.
2005-01-01
A particular method of writing the bound state wave functions in relativistic form is applied to the solutions of the Dirac equation with confining potentials in order to obtain a relativistic description of a quark antiquark bound system representing a given meson. Concerning the role of the effective constituent in the present approach we first observe that without this additional constituent we couldn't expand the bound state wave function in terms of products of free states. Indeed, we notice that if the wave function depends on the relative coordinates only, all the expansion coefficients would be infinite. Secondly we remark that the effective constituent enabled us to give a Lorentz covariant meaning to the potential energy of the bound system which is now seen as the 4th component of a 4-momentum. On the other side, by relating the effective constituent to the quantum fluctuations of the background field which generate the binding, we provided a justification for the existence of some spatial degrees of freedom accompanying the interaction potential. These ones, which are quite unusual in quantum mechanics, in our model are the natural consequence of the the independence of the quarks and can be seen as the effect of the imperfect cancellation of the vector momenta during the quantum fluctuations. Related with all these we remark that the adequate representation for the relativistic description of a bound system is the momentum representation, because of the transparent and easy way of writing the conservation laws and the transformation properties of the wave functions. The only condition to be fulfilled is to find a suitable way to take into account the potential energy of the bound system. A particular feature of the present approach is that the confining forces are due to a kind of glue where both quarks are embedded. This recalls other bound state models where the wave function is factorized in terms of constituent wave functions and the confinement is
International Nuclear Information System (INIS)
Zouzou, S.
1986-01-01
In the framework of simple non-relativistic potential models, we examine the system consisting of two quarks and two antiquarks with equal or unequal masses. We search for possible bound states below the threshold for the spontaneous dissociation into two mesons. We solve the four body problem by empirical or systematic variational methods and we include the virtual meson-meson components of the wave function. With standard two-body potentials, there is no proliferation of multiquarks. With unequal quark masses, we obtain however exotic (anti Qanti Qqq) bound states with a baryonic antidiquark-quark-quark structure very analogous to the heavy flavoured (Q'qq) baryons. (orig.)