Alpha Decay of Even-Even Superheavy Nuclei
International Nuclear Information System (INIS)
Oudih, M.R.; Hamza, Y.; Fellah, M.; Allal, N.H.; Fellah, M.; Allal, N.H.
2011-01-01
Alpha decay properties of even-even superheavy nuclei with 112.Z.120 have been investigated using the Hartree-Fock-Bogoliubov approach. The method is based on the SkP Skyrme interaction and the Lipkin-Nogami prescription for treating the pairing correlations. The alpha decay energies are extracted from the binding energies and then used for the calculation of the decay half-lives using a formula similar to that of Viola-Seaborg. The parameters of the formula were obtained through a least square fit to even-even heavy nuclei taken from the tables of Audi- Wapstra and some more recent references. The results are compared with other theoretical evaluations.
Excited bands in even-even rare-earth nuclei
International Nuclear Information System (INIS)
Vargas, Carlos E.; Hirsch, Jorge G.
2004-01-01
The energetics of states belonging to normal parity bands in even-even dysprosium isotopes, and their B(E2) transition strengths, are studied using an extended pseudo-SU(3) shell model. States with pseudospin 1 are added to the standard pseudospin 0 space, allowing for a proper description of known excited normal parity bands
Study of Triaxial deformation variable γ in even - even nuclei
International Nuclear Information System (INIS)
Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Sharma, Aparna; Varshney, A.K.; Singh, M.; Gupta, D.K.; Varshney, Mani; Dhiman, S.K.
2011-01-01
The deformation parameters β and γ of the collective model are basic description of the nuclear equilibrium shape and structure, while values for these variables have been discussed for many nuclei. A systematic study in mass region A = 120-140 and A = 150 -180 can never be less revealing, such study has been presented, in A = 90 -120 for Mo, Ru and Pd nuclei where β and γ both vary strongly
Quartetting in even-even and odd-odd N=Z nuclei
Sambataro, M.; Sandulescu, N.
2018-02-01
We report on a microscopic description of even-even N = Z nuclei in a formalism of quartets. Quartets are four-body correlated structures characterized by isospin T and angular momentum J. We show that the ground state correlations induced by a realistic shell model interaction can be well accounted for in terms of a restricted set of T = 0 low-J quartets, the J = 0 one playing by far a leading role among them. A conceptually similar description of odd-odd self-conjugate nuclei is given in terms of two distinct families of building blocks, one formed by the same T = 0 quartets employed for the even-even systems and the other by collective pairs with either T = 0 or T = 1. Some applications of this formalism are discussed for nuclei in the sd shell.
Damping of isovector giant dipole resonances in hot even-even spherical nuclei
International Nuclear Information System (INIS)
Dang, N.D.
1989-01-01
An approach based on the finite temperature quasiparticle phonon nuclear model (FT-QPNM) with the couplings to (2p2h) states at finite temperature taken into account is suggested for calculations of the damping of giant multipole resonances in hot even-even spherical nuclei. The strength functions for the isovector giant dipole resonance (IV-GDR) are calculated in 58 Ni and 90 Zr for a range of temperatures up to 3 MeV. The results show that the contribution of the interactions with (2p2h) configurations to the IV-GDR spreading width changes weakly with varying temperature. The IV-GDR centroid energy decreases slightly with increasing temperature. The nonvanishing superfluid pairing gap due to thermal fluctuations is included. (orig.)
Comparison of the Porter-Thomas distribution with neutron resonance data of even-even nuclei
International Nuclear Information System (INIS)
Camarda, H.S.
1994-01-01
The low-energy neutron resonance data of the even-even nuclei 152 Sm, 158 Gd, 162 Dy, 166,168 Er, 182 W, 232 Th, and 236,238 U have been examined in order to test the validity of the Porter-Thomas distribution of the reduced neutron widths---a chi-squared distribution with one degree of freedom (v=1). In an attempt to circumvent the ever-present problems of missed or spurious s wave levels as well as extra p wave levels, a maximum likelihood statistic was employed which used only measured widths greater than some minimum value. A Bayes-theory test applied to the data helped to ensure that p wave contamination of the s wave level population was not significant. The error-weighted value of the number of degrees of freedom for the nine nuclei studied, left-angle v right-angle=0.98±0.10, is consistent with the theoretical expectation of v=1
Coexistence in even-even nuclei with emphasis on the germanium isotopes
International Nuclear Information System (INIS)
Carchidi, M.A.V.
1985-01-01
No simple model to date can explain in a self-consistent way the results of direct transfer data and BE2 electromagnetic rates in the germanium isotopes. The simplest models use a two-state interaction for describing the ground state and first excited O + state. In all cases, these models can account for some of the data, but they are in drastic conflict with other experimental measurements. In this thesis, it is shown that a two-state model can consistently account for two-neutron and alpha transfer O + 2 /g.s. cross-section ratio data in the germanium region (ie. zinc, germanium, and selenium), proton occupation number data in the ground states of the even stable zinc, germanium, and selenium isotopes, and BE2 transition rates in isotopes of germanium and zinc. In addition the author can account for most of the one-neutron and two-neutron transfer O + 2 /g.s. and (9/2 + 2 )/(9/2 + 1 ) cross-section ratio data in the odd-mass germanium isotopes. In this generalized two-state model (called Rerg1), the author makes as few assumptions as possible about the nature of the basis states; rather the author allows the experimental data to dictate the properties of the basis-state overlaps. In this sense, the author has learned much about the basis states and has a useful tool for constructing them. The author also shows that the Rerg1 model can quantitatively account for all two-neutron O + 2 /g.s. cross-section ratio data in all even-even nuclei from calcium to uranium
Validity of single term energy expression for ground state rotational band of even-even nuclei
International Nuclear Information System (INIS)
Sharma, S.; Kumar, R.; Gupta, J.B.
2005-01-01
Full text: There are large numbers of empirical studies of gs band of even-even nuclei in various mass regions. The Bohr-Mottelson's energy expression is E(I) = AX + BX 2 +CX 3 +... where X = I(I+1). The anharmonic vibrator energy expression is: E(I) = al + bl 2 + cl 3 SF model with energy expression: E(I)= pX + qI + rXI... where the terms represents the rotational, vibrational and R-V interaction energy, respectively. The validity f the various energy expressions with two terms had been tested by Sharma for light, medium and heavy mass regions using R I s. R 4 plots (where, spin I=6, 8, 10, 12), which are parameter independent. It was also noted, that of the goodness of energy expression can be judged with the minimum input of energies (i.e. only 2 parameters) and predictability's of the model p to high spins. Recently, Gupta et. al proposed a single term energy expression (SSTE) which was applied for rare earth region. This proposed power law reflected the unity of rotation - vibration in a different way and was successful in explaining the structure of gs-band. It will be useful for test the single term energy expression for light and heavy mass region. The single term expression for energy of ground state band can be written as: E I =axI b , where the index b and the coefficient a are the constant for the band. The values of b+1 and a 1 are as follows: b 1 =log(R 1 )/log(I/2) and a 1 =E I /I b ... The following results were gained: 1) The sharp variation in the value of index b at given spin will be an indication of the change in the shape of the nucleus; 2) The value of E I /I b is fairly constant with spin below back-bending, which reflects the stability of shape with spin; 3) This proposed power law is successful in explaining the structure of gs-band of nuclei
Prediction of energies of yrast band in some even-even nuclei
International Nuclear Information System (INIS)
Varshney, A.K.; Singh, Yuvraj; Gupta, D.K.; Singh, M.; Gupta, K.K.; Bihari, Chhail; Dhiman, S.K.
2012-01-01
The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. The researchers found that the values of γ obtained from energies (= γ e ) are nearly equal to the value of γ derived from transition rate (= γ b ) in even Xe, Ba and Ce nuclei (A∼120-140) and Hf, W, Os, Pt and Hg nuclei (A∼160-200) using rigid triaxial rotor model of Davydov-Filippov. In the present study, the relatively light mass nuclei (Mo, Ru and Pd) have been taken. As far as γ is concerned, it is known that the Ru chains of nuclei is intermediate between the two having opposite trends for parameter γ, decreasing for Mo and increasing for Pd, and has an irregular behaviour in itself with the increase of neutron number
Two-Neutron Separation Energies Of Even-Even Rare-Earth Neutron-Rich Nuclei
International Nuclear Information System (INIS)
Benhamouda, N.; Oudih, M. R.; Allal, N. H.; Fellah, M.
2007-01-01
The variation of the two-neutron separation energy (S2N), as a function of N, is studied using a microscopic model that includes the pairing effects rigorously within the Fixed-Sharp-BCS method. The model has been tested for ''ordinary'' nuclei and has correctly reproduced the experimental data. The study has then been extended to the neutron-rich nuclei and has shown a relatively important variation of S2N when N= 100 which may be attributed to the existence of a new magic number
Systematics of measured fission half lives of even even superheavy nuclei
International Nuclear Information System (INIS)
Bhagwat, A.; Gupta, M.; Gambhir, Y.K.
2011-01-01
The production and study of superheavy nuclei is of current interest. Elements upto Z = 118 have been produced so far, and their decay properties have been studied in detail. In the shell stabilised superheavy region, spontaneous fission competes with decay and must be taken into account as an important decay mode. Therefore, the study of fission becomes particularly important in the context of the formation and survival of the superheavy nuclei. A fully microscopic description of the fission phenomenon and hence the fission half lives, though highly desirable, is far from being realised due to the extreme complexity of the fission process. Hence a phenomenological description of the fission process is attempted here
Regional regularities for the even-even nuclei in intermediate mass region
International Nuclear Information System (INIS)
Varshney, Mani; Singh, M.; Gupta, D.K.; Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Sharma, Aparna; Varshney, A.K.
2011-01-01
With the development of experimental techniques more and more nuclear data are accumulated and compiled for over five decades. The proton neutron interaction has been considered the key ingredient in the development of collectivity and ultimately the deformation in atomic nuclei. The purpose of the present study is to analyze the growth of R4/2 in different mass regions. The rate of growth regions in regions having proton number Z = 38, 54, 60 and 76 with changing neutron number where the interaction between particle - particle, particle - hole and hole - hole
Triaxial quadrupole dynamics and the inner fission barrier of some heavy even-even nuclei
Benrabia, K.; Medjadi, D. E.; Imadalou, M.; Quentin, P.
2017-09-01
Background: Inner fission barriers of actinide nuclei have been known for a long time to be unstable with respect to the axial symmetry. On the other hand, taking into account the effect of the relevant adiabatic mass parameter reduces or even may wash out this instability. A proper treatment of the dynamics for both axial and triaxial modes is thus crucial to accurately determine the corresponding fission barriers. This entails in particular an accurate description of pairing correlations. Purpose: We evaluate the potential energies, moments of inertia, and vibrational mass parameters in a two-dimensional relevant deformation space (corresponding to the usual β and γ quadrupole deformation parameters) for four actinide nuclei (236U, 240Pu, 248Cm, and 252Cf). We assess the relevance of our approach to describe the dynamics for a triaxial mode by computing the low energy spectra (exploring thus mainly the equilibrium deformation region). We evaluate the inner fission barrier heights releasing the axial symmetry constraint. Method: Calculations within the Hartree-Fock plus BCS approach are performed using the SkM* Skyrme effective interaction in the particle-hole channel and a seniority force in the particle-particle channel. The intensity of this residual interaction has been fixed to allow a good reproduction of some odd-even mass differences in the actinide region. Adiabatic mass parameters for the rotational and vibrational modes are calculated using the Inglis-Belyaev formula supplemented by a global renormalization factor taking into account the so-called Thouless-Valatin corrections. Spectra are obtained through the diagonalization of the corresponding Bohr collective Hamiltonian. Results: The experimental low energy spectra are qualitatively well reproduced by our calculations for the considered nuclei. Inner fission barrier heights are calculated and compared with available estimates from various experimental data. The reproduction of the data is better
Systematic study of even-even nuclei with Hartree-Fock+BCS method using Skyrme SIII force
Energy Technology Data Exchange (ETDEWEB)
Tajima, Naoki; Takahara, Satoshi; Onishi, Naoki [Tokyo Univ. (Japan). Coll. of Arts and Sciences
1997-03-01
We have applied the Hartree-Fock+BCS method with Skyrme SIII force formulated in a three-dimensional Cartesian-mesh representation to even-even nuclei with 2 {<=} Z {<=} 114. We discuss the results concerning the atomic masses, the quadrupole (m=0, 2) and hexadecapole (m=0, 2, 4) deformations, the skin thicknesses, and the halo radii. We also discuss the energy difference between oblate and prolate solutions and the shape difference between protons and neutrons. (author)
A systematic study of even-even nuclei in the nuclear chart by the relativistic mean field theory
Energy Technology Data Exchange (ETDEWEB)
Sumiyoshi, K.; Hirata, D.; Tanihata, I.; Sugahara, Y.; Toki, H. [Institute of Physical and Chemical Research, Wako, Saitama (Japan)
1997-03-01
We study systematically the properties of nuclei in the whole mass range up to the drip lines by the relativistic mean field (RMF) theory with deformations as a microscopic framework to provide the data of nuclear structure in the nuclear chart. The RMF theory is a phenomenological many-body framework, in which the self-consistent equations for nucleons and mesons are solved with arbitrary deformation, and has a potential ability to provide all the essential information of nuclear structure such as masses, radii and deformations together with single particle states and wave functions from the effective lagrangian containing nuclear interaction. As a first step toward the whole project, we study the ground state properties of even-even nuclei ranging from Z=8 to Z=120 up to the proton and neutron drip lines in the RMF theory. We adopt the parameter set TMA, which has been determined by the experimental masses and charge radii in a wide mass range, for the effective lagrangian of the RMF theory. We take into account the axially symmetric deformation using the constrained method on the quadrupole moment. We provide the properties of all even-even nuclei with all the possible ground state deformations extracted from the deformation energy curves by the constrained calculations. By studying the calculated ground state properties systematically, we aim to explore the general trend of masses, radii and deformations in the whole region of the nuclear chart. We discuss the agreement with experimental data and the predictions such as magicness and triaxial deformations beyond the experimental frontier. (author)
Symmetries of Quadrupole-Collective Vibrational Motion in Transitional Even-Even 124−134Xenon Nuclei
Pietralla, N; Rainovski, G; Ahn, T; Bauer, C; Leske, J; Möller, O; Möller, T
2010-01-01
Projectile-Coulomb excitation of Xe isotopes has been performed at ANL using the Gammasphere array for the detection of γ-rays. The one-quadrupole phonon 2+ 1,ms mixed-symmetry state (MSS) has been traced in the stable N=80 isotones down to 134Xe. First, the data on absolute E2 andM1 transition rates quantify the amount of F-spin symmetry in these nuclei and provide a new local measure for the pn-QQ interaction. Second, the evolution of the 2+ 1,ms state has been studied along the sequence of stable even-even 124−134Xe isotopes that are considered to form a shape transition path from vibrational nuclei with vibrational U(5) symmetry near N=82 to γ-softly deformed shapes with almost O(6) symmetry. Third, our data on more than 50 absolute E2 transition rates between off-yrast low-spin states of 124,126Xe enable us to quantitatively test O(6) symmetry in these nuclei. As a result we find that O(6) symmetry is more strongly broken in the A=130 mass region than previously thought. The data will be discussed.
The Hartree-Fock approximation for s-d shell even-even nuclei with N different of Z
International Nuclear Information System (INIS)
Oliveira, P.C. de.
1981-02-01
Using the Hartree-Fock approximation method for 22 Ne, 26 Mg and 30 Si nuclei with different kinds of two-body interactions, the electric quadrupole moments and projected energy levels, of angular momentum J=0,2,4,6..., are determined. The Peierls-Yoccoz projection m ethod is used to determine the wave function with well-defined angular momentum. A comparison is made, with the experimental results and the ones obtained by other authors. (Author) [pt
Robin, C.; Pillet, N.; Dupuis, M.; Le Bloas, J.; Peña Arteaga, D.; Berger, J.-F.
2017-04-01
Background: The variational multiparticle-multihole configuration mixing approach to nuclei has been proposed about a decade ago. While the first applications followed rapidly, the implementation of the full formalism of this method has only been recently completed and applied in C. Robin, N. Pillet, D. Peña Arteaga, and J.-F. Berger, [Phys. Rev. C 93, 024302 (2016)], 10.1103/PhysRevC.93.024302 to 12C as a test-case. Purpose: The main objective of the present paper is to carry on the study that was initiated in that reference, in order to put the variational multiparticle-multihole configuration mixing method to more stringent tests. To that aim we perform a systematic study of even-even s d -shell nuclei. Method: The wave function of these nuclei is taken as a configuration mixing built on orbitals of the s d -shell, and both the mixing coefficients of the nuclear state and the single-particle wave functions are determined consistently from the same variational principle. As in the previous works, the calculations are done using the D1S Gogny force. Results: Various ground-state properties are analyzed. In particular, the correlation content and composition of the wave function as well as the single-particle orbitals and energies are examined. Binding energies and charge radii are also calculated and compared to experiment. The description of the first excited state is also examined and the corresponding transition densities are used as input for the calculation of reaction processes such as inelastic electron and proton scattering. Special attention is paid to the effect of the optimization of the single-particle states consistently with the correlations of the system. Conclusions: The variational multiparticle-multihole configuration mixing approach is systematically applied to the description of even-even s d -shell nuclei. Globally, the results are satisfying and encouraging. In particular, charge radii and excitation energies are nicely reproduced. However
International Nuclear Information System (INIS)
Souw, Kenghok.
1975-01-01
A new high efficiency plastic scintillation pair spectrometer was used to measure the E0 branching ratio GAMMAsub(π)/GAMMA(tot) (GAMMAsub(π)=pair emission partial width, GAMMA(tot)=total width) of the transition from the first excited Jsup(π)=0 + state to the Jsup(π)=0 + ground state in some even-even nuclei of the 2s-1d shell. Experiments were performed on 18 O, 26 Mg, 30 Si, 32 S, 34 S and 38 Ar nuclei. The method consisted in detecting the electron and positron of the pair in coincidence in two telescopes. A surface barrier counter placed downstream the target, working in coincidence with the spectrometer, allowed the relevant pair-decays to be selected and the feeding yield to be determined from direct spectra. The branching ratios were such directly determined. These ratios combined with the values available for the lifetimes of these states give the monopole matrix elements Msub(π). The single particle strength of these decays passes through a minimum in the middle of the shell ( 30 Si) and reaches a maximum around the closed shells ( 18 O, and 48 Ca) [fr
Pattnaik, S.; Nayak, R. C.
2014-04-01
We obtain here a new relation for the reduced electric quadrupole transition probability B(E2)↑ of a given nucleus in terms of its derivatives with respect to neutron and proton numbers based on a similar local energy relation in the Infinite Nuclear Matter (INM) model of atomic nuclei, which is essentially built on the foundation of the Hugenholtz-Van Hove (HVH) theorem of many-body theory. Obviously, such a relation in the form of a differential equation is expected to be more powerful than the usual algebraic difference equations. Although the relation for B(E2)↑ has been perceived simply on the basis of a corresponding differential equation for the local energy in the INM model, its theoretical foundation otherwise has been clearly demonstrated. We further exploit the differential equation in using the very definitions of the derivatives to obtain two different recursion relations for B(E2)↑, connecting in each case three neighboring even-even nuclei from lower to higher mass numbers and vice versa. We demonstrate their numerical validity using available data throughout the nuclear chart and also explore their possible utility in predicting B(E2)↑ values.
International Nuclear Information System (INIS)
Singh, Yuvraj; Gupta, D.K.; Singh, M.; Gupta, K.K.; Bihari, Chhail; Varshney, A.K.; Dhiman, S.K.
2012-01-01
The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. In recent past the sets of deformation parameters ((β, γ) have been extracted from both level energies and E2 transition rates in even Xe, Ba and Ce nuclei (A∼120-140) and Hf, W, Os, Pt and Hg nuclei (A∼160-200) using rigid triaxial rotor model of Davydov-Filippov (DF). Researcher have found that the values of β obtained separately from energy and transition rate (β e and β b respectively), though, are found almost equal in heavy mass region (A ∼160-200) but, not so in medium mass (A∼120-140) nuclei. This observation puts a question mark whether the ββ dependence of moment of inertia in hydrodynamic model is reliable. The purpose of the present work is to study a relatively lighter mass region (A∼90-120) where the gap between values of two sets of β may further increase. To improve the calculations for extracting β e , the use of Grodzins rule will be made along with uncertainties, since only through this rule the E2 1 + is related with β G (value of β for symmetric nucleus and evaluated using Grodzins rule)
Phases of dense matter with non-spherical nuclei
Energy Technology Data Exchange (ETDEWEB)
Pethick, C.J. [NORDITA, Copenhagen (Denmark)]|[Dept. of Physics, Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States); Ravenhall, D.G. [Dept. of Physics, Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
1998-06-01
A brief review is given of some of the important physics related to phases with non-spherical nuclei that can exist in neutron stars and in matter in stellar collapse at densities just below the saturation density of nuclear matter. Comparisons are made with other systems that exhibit similar liquid-crystal-like phases, both in nuclear physics and in condensed matter physics. A short account is given of recent work on the elastic properties of these phases, and their vibration spectrum, as well as on neutron superfluid gaps. (orig.)
Benbouzid, Y.; Allal, N. H.; Fellah, M.; Oudih, M. R.
2018-04-01
Isovector neutron-proton (np) pairing and particle-number fluctuation effects on the spectroscopic factors (SF) corresponding to one-pair like-particle transfer reactions in proton-rich even-even nuclei are studied. With this aim, expressions of the SF corresponding to two-neutron stripping and two-proton pick-up reactions, which take into account the isovector np pairing effect, are established within the generalized BCS approach, using a schematic definition proposed by Chasman. Expressions of the same SF which strictly conserve the particle number are also established within the Sharp-BCS (SBCS) discrete projection method. In both cases, it is shown that these expressions generalize those obtained when only the pairing between like particles is considered. First, the formalism is tested within the Richardson schematic model. Second, it is applied to study even-even proton-rich nuclei using the single-particle energies of a Woods-Saxon mean-field. In both cases, it is shown that the np pairing effect and the particle-number projection effect on the SF values are important, particularly in N = Z nuclei, and must then be taken into account.
Non-spherical boson basis for near-O(6) nuclei
International Nuclear Information System (INIS)
Leviatan, A.
1984-01-01
A non-spherical boson basis is suggested for the description of near-O(6) nuclei. The structure of intrinsic states in such nuclei is studied and analytic expressions for the bandheads and E2 transitions are given, accompanied by a comparison with the experimental data. (orig.)
Phase Transitions in Even-Even Palladium Isotopes
Directory of Open Access Journals (Sweden)
Diab S. M.
2009-01-01
Full Text Available The positive and negative parity states of the even-even palladium isotopes were studied within the frame work of the interacting boson approximation model (IBA-1. The energy spectra, potential energy surfaces, electromagnetic transition probabilities, back bending and staggering effect have been calculated. The potential energy surfaces show smooth transition from vibrational-like to gamma-soft and finally to rotational-like nuclei. Staggering effectle, has been observed between the positive and negative parity states in palladium isotopes. The agreement between theoretical predictions and experimental values are fairly good.
Phase Transitions in Even-Even Palladium Isotopes
Directory of Open Access Journals (Sweden)
Diab S. M.
2009-01-01
Full Text Available The positive and negative parity states of the even-even palladium isotopes were stud- ied within the frame work of the interacting boson approximation model (IBA-1. The energy spectra, potential energy surfaces, electromagnetic transition probabilities, back bending and staggering effect have been calculated. The potential energy surfaces show smooth transition from vibrational-like to gamma-soft and finally to rotational-like nu- clei. Staggering effectle, has been observed between the positive and negative parity states in palladium isotopes. The agreement between theoretical predictions and exper- imental values are fairly good.
Spin dependence of even-even nucleus shape in the model of Davydov-Chaban
Kashuba, I E
2002-01-01
The shape parameters of the even-even nuclei sup 1 sup 5 sup 4 Gd, sup 1 sup 5 sup 6 sup , sup 1 sup 5 sup 8 sup , sup 1 sup 6 sup 0 Dy, sup 1 sup 6 sup 4 sup , sup 1 sup 6 sup 8 Er, sup 1 sup 6 sup 8 Yb, sup 1 sup 7 sup 6 Hf, sup 1 sup 8 sup 0 W are calculated within the phenomenological model of the nonaxial soft by beta-oscillation deformed nucleus. The spin dependence of the softness, nonaxiality and energy factor is assumed
The first observation of EO transitions from negative parity states in even-even nucleus 160Dy
International Nuclear Information System (INIS)
Grigoriev, E.P.
1988-01-01
In even-even deformed nuclei up to now EO-transitions were found only between the states of the same spin belonging to Κ π = O + rotational bands. There is no forbidenness for EO-transitions between states belonging to bands with any other quantum number Κ provided both initial and final states have the same J π Κ values. EO-transitions may depopulate odd-parity states. In odd nuclei β-vibrational states are identified by transition with EO-components. Here transitions also proceed between states with the same J π K numbers. Even-even nuclide 160 Dy is the first nucleus where the EO-transitions between odd-parity states have been found
Predicting the optical observables for nucleon scattering on even-even actinides
Martyanov, D. S.; Soukhovitskiĩ, E. Sh.; Capote, R.; Quesada, J. M.; Chiba, S.
2017-09-01
The previously derived Lane consistent dispersive coupled-channel optical model for nucleon scattering on 232Th and 238U nuclei is extended to describe scattering on even-even actinides with Z = 90-98. A soft-rotator-model (SRM) description of the low-lying nuclear structure is used, where the SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions (mixed in K quantum number) have been used to calculate the coupling matrix elements of the generalized optical model. The “effective” deformations that define inter-band couplings are derived from the SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a dynamic monopolar term to the deformed potential, leading to additional couplings between rotational bands. The fitted static deformation parameters are in very good agreement with those derived by Wang and collaborators using the Weizsäcker-Skyrme global mass model (WS4), allowing use of the latter to predict cross sections for nuclei without experimental data. A good description of the scarce “optical” experimental database is achieved. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus formation cross sections, which is significantly different from that calculated with rigid-rotor potentials coupling the ground-state rotational band. The derived parameters can be used to describe both neutron- and proton-induced reactions. Supported by International Atomic Energy Agency, through the IAEA Research Contract 19263, by the Spanish Ministry of Economy and Competitivity under Contracts FPA2014-53290-C2-2-P and FPA2016-77689-C2-1-R.
Search for α + core states in even-even Cr isotopes
Energy Technology Data Exchange (ETDEWEB)
Souza, M.A. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo, SP (Brazil); Instituto Federal de Educacao, Ciencia e Tecnologia de Sao Paulo, Departamento de Mecanica, Sao Paulo, SP (Brazil); Miyake, H. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo, SP (Brazil)
2017-07-15
The α + core structure is investigated in even-even Cr isotopes from the viewpoint of the local potential model. The comparison of Q{sub α}/A values for even-even Cr isotopes and even-even A = 46, 54, 56, 58 isobars indicates that {sup 46}Cr and {sup 54}Cr are the most favorable even-even Cr isotopes for the α + core configuration. The ground state bands of the two Cr isotopes are calculated through a local α + core potential containing a nuclear term with (1 + Gaussian) x (W.S. + W.S.{sup 3}) shape. The calculated spectra give a very good description of most experimental {sup 46}Cr and {sup 54}Cr levels, including the 0{sup +} bandheads. The reduced α-widths, rms intercluster separations and B(E2) transition rates are determined for the ground state bands. The calculations reproduce the order of magnitude of the available experimental B(E2) values without using effective charges, indicate that the low-spin members of the ground state bands present a stronger α-cluster character, and point out that the {sup 46}Cr ground state band has a significant degree of α-clustering in comparison with {sup 44}Ti. The volume integral per nucleon pair and rms radius obtained for the α + {sup 50}Ti potential are consistent with those reported previously in the analysis of α elastic scattering on {sup 50}Ti. (orig.)
Microscopic investigation of structural evolution in even-even N = 60 isotones
International Nuclear Information System (INIS)
Oudih, M. R.; Fellah, M.; Allal, N. H.; Benhamouda, N.
2012-01-01
The ground state properties of even-even N=60 isotones from the neutron-rich to the proton-rich side are investigated within the self-consistent Skyrme-Hartree-Fock-Bogoliubov theory in the triaxial landscape. Quantities such as binding energies and root-mean-square radii are investigated and compared with available experimental data. The evolution of the potential energy surfaces in the (β,γ) deformation plane is presented and discussed.
International Nuclear Information System (INIS)
Kitazawa, H.; Igashira, M.; Shimizu, M.; Muto, K.; Oda, T.; Achiha, Y.; Lee, Y.; Mukai, N.
1992-01-01
Observations have been performed for electromagnetic transitions from the broad s-wave neutron resonances at 658 keV in 24 Mg, at 180 keV in 28 Si, and at 103 keV in 32 S. Capture gamma rays were measured with an anti-Compton NaI(Tl) detector, using a neutron time-of-flight technique. E1 and M1 transitions from those resonances to low-lying states with a strong single-particle character were found. The deduced partial radiative widths for E1 transition are in excellent agreement with the Lane-Mughabghab valence-capture model calculations taking the neutron effective charge, -Ze/A. Moreover, it is shown that essential features of the observed E1 and M1 transitions can be well explained by assuming a configuration-mixing wave function, Ψ i (1/2 + )=a(0 + direct-product 1/2 + )+b(1 + direct-product 1/2 + )+c(1 + direct-product 3/2 + ), for each resonance. The M1 transition strengths are compared also with more detailed shell model calculations in the model space of full (sd) n configurations, using the Wildenthal effective interaction
Potential Energy Surfaces of the Even-Even 230-238 U Isotopes
Directory of Open Access Journals (Sweden)
Sohair M. Diab
2008-07-01
Full Text Available Nuclear structure of 230-238 U isotopes hav been studied in the frame work of the interacting boson approximation model (IBM-1. The contour plot of the potential energy surfaces, $V(eta,gamma$, shows that all nuclei are deformed and have rotational characters, $SU(3$. Levels energy spectra belonging to the $gsb$, $eta $, $gamma $ bands, electromagnetic transition rates $B(E1$ and $ B(E2$, quadrupole moment $Q_0 $, deformation parameter are $eta_2$ and the strength of the electric monopole transitions $X(E0/E2$ are calculated. The calculated values are compared with the available theoretical and experimental data and show reasonable agreement.
Potential Energy Surfaces of the Even-Even 230-238 U Isotopes
Directory of Open Access Journals (Sweden)
Diab S. M.
2008-07-01
Full Text Available Nuclear structure of 230 - 238 U isotopes have been studied in the frame work of the in- teracting boson approximation model (IBM-I. The contour plot of the potential energy surfaces, V ( ; , shows that all nuclei are deformed and have rotational char- acters, SU (3 . Levels energy spectra belonging to the gsb , , bands, electromagnetic transition rates B ( E 1 and B ( E 2 , quadrupole moment Q 0 , deformation parameterare 2 and the strength of the electric monopole transitions X ( E 0 =E 2 are calculated. The calculated values are compared with the available theoretical and experimental data and show reasonable agreement.
High-spin states in 214Rn, 216Ra and a study of even-even N = 128 systematics
International Nuclear Information System (INIS)
Loennroth, T.; Horn, D.; Baktash, C.; Lister, C.J.; Young, G.R.
1983-01-01
High-spin states in 214 Rn and 216 Ra have been studied by means of the reaction 208 Pb( 13 C, α 3n #betta#) 214 Rn and 208 Pb( 13 C, 5n #betta#) 216 Ra at beam energies in the range 75--95 MeV. In-beam spectroscopy techniques, including #betta#-decay excitation functions, α-#betta# coincidences, #betta#-#betta# coincidences, #betta#-ray angular distributions, and pulsed-beam-#betta# timing, were utilized to establish level energies, #betta#-ray multipolarities, J/sup π/ assignments, and isomeric lifetimes. Excited states with spins up to 23h in 214 Rn and roughly-equal30h in 216 Ra were observed. Isomers were found in 214 Rn at 1625 keV (T/sub 1/2/ = 9 ns, J/sup π/ = 8 + ), 1787 keV (22 ns, 10 + ), 3485 keV (95 ns, 16), 4509 keV (230 ns, 20), and 4738 keV (8 ns, 22), and in 216 Ra at 1708 keV (8 ns, 8 + ) and 5868 keV (10 ns, approx.24). B(EL) values were deduced and compared to previously known lead-region electric transition rates. Shell-model calculations were performed and used to make configurational assignments. The absence of major α-decay branching in the isomers is explained and the systematic behavior of N = 128 even-even nuclei is discussed
Study of elastic and inelastic scattering of 16O on even-even Sm isotopes
International Nuclear Information System (INIS)
Talon, Pascal.
1979-01-01
The recent equipment of tandem accelerators devoted to the study of heavy ion interactions with high-resolution magnetic spectrometers has enabled long-range effects to be observed during elastic scattering on deformed nuclei. These phenomena were studied as a function of energy around the Coulomb barrier and of Sm isotope deformation. Analyses by simple analytical formulae or using the optical model with an effective potential introducing an imaginary part into the Coulomb potential have fully confirmed that these long-range effects are induced by Coulomb excitation. A coupled channel analysis is shown to give access to nuclear deformation parameters. High resolution studies on the elastic scattering of heavy ions opens up a very interesting field of application for the study of deformed nuclei. The Coulomb barrier was seen to be lowered by the angular behavior of the Q opt of transfer reactions ( 16 O, 14 C) and ( 16 O, 12 C) on deformed Sm isotopes. It is now well known that the transfer of some nucleons induced by heavy ions can proceed from a two-stage mechanism. It may be supposed that the strong Coulomb excitation of a level can create the wave function overlapping conditions necessary to a nuclear transfer [fr
Structure of Even-Even 218-230 Ra Isotopes within the Interacting Boson Approximation Model
Directory of Open Access Journals (Sweden)
Diab S. M.
2008-01-01
Full Text Available A good description of the excited positive and negative parity states of radium nuclei (Z=88, N=130-142 is achieved using the interacting boson approximation model (IBA-1. The potential energy surfaces, energy levels, parity shift, electromagnetic transition rates B(E1, B(E2 and electric monopole strength X(E0/E2 are calculated for each nucleus. The analysis of the eigenvalues of the model Hamiltonian reveals the presence of an interaction between the positive and negative parity bands. Due to this interaction the $Delta I = 1$ staggering effect, between the energies of the ground state band and the negative parity state band, is produced including beat patterns.
High-spin states in 214Rn, 216Ra and a study of even-even N=128 systematics
Lönnroth, T.; Horn, D.; Baktash, C.; Lister, C. J.; Young, G. R.
1983-01-01
High-spin states in 214Rn and 216Ra have been studied by means of the reaction 208Pb(13C, α 3n γ)214Rn and 208Pb(13C, 5n γ)216Ra at beam energies in the range 75-95 MeV. In-beam spectroscopy techniques, including γ-decay excitation functions, α-γ coincidences, γ-γ coincidences, γ-ray angular distributions, and pulsed-beam-γ timing, were utilized to establish level energies, γ-ray multipolarities, Jπ assignments, and isomeric lifetimes. Excited states with spins up to 23ℏ in 214Rn and ~30ℏ in 216Ra were observed. Isomers were found in 214Rn at 1625 keV (T12=9 ns, Jπ=8+), 1787 keV (22 ns, 10+), 3485 keV (95 ns, 16), 4509 keV (230 ns, 20), and 4738 keV (8 ns, 22), and in 216Ra at 1708 keV (8 ns, 8+) and 5868 keV (10 ns, ~24). B(EL) values were deduced and compared to previously known lead-region electric transition rates. Shell-model calculations were performed and used to make configurational assignments. The absence of major α-decay branching in the isomers is explained and the systematic behavior of N=128 even-even nuclei is discussed. NUCLEAR STRUCTURE 208Pb(13C, α 3n γ)214Rn, 208Pb(13C, 5n γ) 216Ra, Elab=75-95 MeV. Measured α-γ coin, γ-γ(t) coin, I(θ), pulsed-beam-γ timing. Deduced level schemes, Jπ, T12, B(EL), multipolarities. Shell model calculations, Ge(Li) and Si detectors, enriched target.
Algebraic description of intrinsic modes in nuclei
International Nuclear Information System (INIS)
Leviatan, A.
1989-01-01
We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. 28 refs., 1 fig
Algebraic description of intrinsic modes in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A.
1989-01-01
We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. 28 refs., 1 fig.
Algebraic description of intrinsic modes in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A. (Los Alamos National Lab., NM (USA))
1990-01-01
We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intrinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. (author).
Algebraic description of intrinsic modes in nuclei
International Nuclear Information System (INIS)
Leviatan, A.
1990-01-01
We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intrinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. (author)
Pushing the pseudo-SU(3) model towards its limits: Excited bands in even-even Dy isotopes
International Nuclear Information System (INIS)
Vargas, Carlos E.; Hirsch, Jorge G.
2004-01-01
The energetics of states belonging to normal parity bands in even-even dysprosium isotopes, and their B(E2) transition strengths, are studied using an extended pseudo-SU(3) shell model. States with pseudospin 1 are added to the standard pseudospin 0 space, allowing for a proper description of known excited normal parity bands. A realistic Hamiltonian is employed. Both the success of model and its limitations are discussed
Energy Technology Data Exchange (ETDEWEB)
Manokhin, Vassily N. [Russian Nuclear Data Center, Institute of Physics and Power Engineering, Obninsk (Russian Federation); Odano, Naoteru; Hasegawa, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2001-03-01
An approach for consistent evaluation of (n,2n) and (n,np) reaction excitation functions for some even-even isotopes with the (n,np) reaction thresholds lower than (n,2n) reaction ones is described. For determination of cross sections in the maximum of the (n,2n) and (n,np) reaction excitation functions some empirical systematics developed by Manokhin were used together with trends in dependence of gaps between the (n,2n) and (n,np) thresholds on atomic mass number A. The shapes of the (n,2n) and (n,np) reaction excitation functions were calculated using the normalized functions from the Manokhin's systematics. Excitation functions of (n,2n) and (n,np) reactions were evaluated for several nuclei by using the systematics and it was found that the approach used for the present study gives reasonable results. (author)
Study of neutron shell structure of even-even 40-56Ca isotopes by the dispersive optical model
International Nuclear Information System (INIS)
Bespalova, O.V.; Boboshin, I.N.; Varlamov, V.V.; Ermakova, T.A.; Ishkhanov, B.S.; Romanovskij, E.A.; Spasskaya, T.I.; Timokhina, T.P.
2005-01-01
The single-particle energies and occupation probabilities of the bound neutron states in 40,42,44,46,48 Ca isotopes were obtained by the joint evaluation of the stripping and pick-up reaction data. The results were analyzed by the dispersive optical model and a good agreement was achieved. The dispersive optical potential was extrapolated to unstable 50,52,54,56 Ca nuclei. The calculated single-particle energies of the bound neutron states in unstable Ca isotopes were compared with the nuclear shell-model calculations, which predicted new magic number N = 34 for nuclei with Z = 20 [ru
Bree, N; Wrzosek-Lipska, K; Petts, A; Andreyev, A; Bastin, B; Bender, M; Blazhev, A; Bruyneel, B; Butler, P A; Butterworth, J; Carpenter, M P; Cederkäll, J; Clément, E; Cocolios, T E; Deacon, A; Diriken, J; Ekström, A; Fitzpatrick, C; Fraile, L M; Fransen, Ch; Freeman, S J; Gaffney, L P; García-Ramos, J E; Geibel, K; Gernhäuser, R; Grahn, T; Guttormsen, M; Hadinia, B; Hadyńska-Kle K, K; Hass, M; Heenen, P-H; Herzberg, R-D; Hess, H; Heyde, K; Huyse, M; Ivanov, O; Jenkins, D G; Julin, R; Kesteloot, N; Kröll, Th; Krücken, R; Larsen, A C; Lutter, R; Marley, P; Napiorkowski, P J; Orlandi, R; Page, R D; Pakarinen, J; Patronis, N; Peura, P J; Piselli, E; Rahkila, P; Rapisarda, E; Reiter, P; Robinson, A P; Scheck, M; Siem, S; Singh Chakkal, K; Smith, J F; Srebrny, J; Stefanescu, I; Tveten, G M; Van Duppen, P; Van de Walle, J; Voulot, D; Warr, N; Wenander, F; Wiens, A; Wood, J L; Zielińska, M
2014-04-25
Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85 MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.
Shape Deformations in Atomic Nuclei
Hamamoto, Ikuko; Mottelson, Ben R.
2011-01-01
The ground states of some nuclei are described by densities and mean fields that are spherical, while others are deformed. The existence of non-spherical shape in nuclei represents a spontaneous symmetry breaking.
Energy Technology Data Exchange (ETDEWEB)
Santhosh, K.P.; Krishnan, Sreejith [Kannur University, School of Pure and Applied Physics, Payyanur, Kerala (India)
2016-04-15
Within the unified ternary fission model (UTFM), the alpha accompanied ternary fission of even-even {sup 244-260}Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. For the alpha accompanied ternary fission of the {sup 244}Cf isotope, the highest yield is obtained for the fragment combination {sup 108}Ru + {sup 4}He + {sup 132}Te, which contains the near doubly magic nucleus {sup 132}Te (N = 80, Z = 52). In the case of {sup 246}Cf and {sup 248}Cf isotopes, the highest yield is obtained for the fragment combinations with the near doubly magic nucleus {sup 134}Te (N = 82, Z = 52) as the heaviest fragment. The highest yield obtained for {sup 250}Cf, {sup 252}Cf, {sup 254}Cf, {sup 256}Cf, {sup 258}Cf and {sup 260}Cf isotopes is for the fragment combination with the doubly magic nucleus {sup 132}Sn (N = 82), Z = 50 as the heaviest fragment. We have included the effect of deformation and orientation of fragments and this has revealed that in addition to the closed shell effect, ground-state deformation also plays an important role in the calculation of the relative yield of favorable fragment combinations. The computed isotopic yields for the alpha accompanied ternary fission of the {sup 252}Cf isotope are found to be in agreement with the experimental data. The emission probability and kinetic energy of the long-range alpha particle is calculated for the various isotopes of Cf and are found to be in good agreement with the experimental data. (orig.)
International Nuclear Information System (INIS)
Spear, R.H.
1988-11-01
Adopted values for the excitation energy, E x( 3 1 - ), of the first 3 - state of the even-even nuclei are tabulated. Values of the reduced electric-octupole transition probability, B(E3;O 1 + → 3 1 - ), from the ground state to this state, as determined from Coulomb excitation, lifetime measurements, inelastic electron scattering, deformation parameters β 3 obtained from angular distributions of inelastically scattered nucleons and light ions, and other miscellaneous procedures are listed in separate Tables. Adopted values for B(E3; O 1 + → 3 1 - ) are presented in Table VII, together with the E3 transition strengths, in Weisskopf units, and the product E x( 3 1 - ) x B(E3; O 1 + → 3 1 - - ) expressed as a percentage of the energy-weighted E3 sum-rule strength. An evaluation is made of the reliability of B(E3; O 1 + → 3 1 - ) values deduced from deformation parameters β 3 . The literature has been covered to March 1988
Directory of Open Access Journals (Sweden)
Morelli L.
2016-01-01
Inclusive variables are in general well reproduced by the model. We found clear deviations from the statistical model if we select emission channels involving multiple α particles which are more probable than expected from a purely statistical behavior. Data from 12C+12C reaction have been analyzed in order to study the decay of the Hoyle state of 12C* with two different selections: peripheral binary collisions and 6α decay channel in central events. To continue the investigation on light systems, we have recently measured the 16O+12C reaction at three different beam energies, namely Ebeam = 90, 110 and 130 MeV. Preliminary results are presented.
International Nuclear Information System (INIS)
Jonah, S.A.
2013-01-01
The EXIFON code version 2.0 is a calculational tool, which is based on both many-body theory and random matrix physics. In this work, it has been used to calculate neutron induced reaction cross section data from 0 to 20 MeV on an even-even, magic number nuclide 52 Cr with neutron number, N=28. Specifically, the (n,p), (n,α) and (n,2n) reaction cross section data were calculated as functions of incident energy of neutrons. Data obtained from the experimental data in the IAEA, EXFOR data Library and recommended data libraries around the globe, JENDL, ENDF and JEFF were used to validate the calculated data. The data indicate that the calculated data without shell corrections are in good agreement with experimental data as well as the recommended data from the evaluated data libraries. The calculated results could provide useful insight into the choice of some input parameters near closed shells using the EXIFON code.
Butler, P; Bastin, B; Kruecken, R; Voulot, D; Rahkila, P J; Orr, N A; Srebrny, J; Grahn, T; Clement, E; Paul, E S; Gernhaeuser, R A; Dorsival, A; Diriken, J V J; Huyse, M L; Iwanicki, J S
The neutron-deficient polonium isotopes with two protons outside the closed Z=82 shell represent a set of nuclei with a rich spectrum of nucleus structure phenomena. While the onset of the deformation in the light Po isotopes is well established experimentally, questions remain concerning the sign of deformation and the magnitude of the mixing between different configurations. Furthermore, controversy is present with respect to the transition from the vibrational-like character of the heavier Po isotopes to the shape coexistence mode observed in the lighter Po isotopes. We propose to study this transition in the even-mass neutron-deficient $^{198,200,202}$Po isotopes by using post-accelerated beams from REX-ISOLDE and "safe"-energy Coulomb excitation. $\\gamma$- rays will be detected by the MINIBALL array. The measurements of the Coulomb excitation differential cross section will allow us to deduce both the transition and diagonal matrix elements for these nuclei and, combined with lifetime measurements, the s...
Hypostatic jammed packings of frictionless nonspherical particles
VanderWerf, Kyle; Jin, Weiwei; Shattuck, Mark D.; O'Hern, Corey S.
2017-01-01
We perform computational studies of static packings of a variety of nonspherical particles including circulo-lines, circulo-polygons, ellipses, asymmetric dimers, and dumbbells to determine which shapes form hypostatic versus isostatic packings and to understand why hypostatic packings of nonspherical particles can be mechanically stable despite having fewer contacts than that predicted from na\\"ive constraint counting. To generate highly accurate force- and torque-balanced packings of circul...
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)
Nonspherical oscilllations of ultrasound contrast agent microbubbles
Dollet, B.; van der Meer, S.M.; Garbin, V.; Garbin, Valeria; de Jong, N.; Lohse, Detlef; Versluis, Michel
2008-01-01
The occurrence of nonspherical oscillations (or surface modes) of coated microbubbles, used as ultrasound contrast agents in medical imaging, is investigated using ultra–high-speed optical imaging. Optical tweezers designed to micromanipulate single bubbles in 3-D are used to trap the bubbles far
Hypostatic jammed packings of frictionless nonspherical particles
VanderWerf, Kyle; Jin, Weiwei; Shattuck, Mark D.; O'Hern, Corey S.
2018-01-01
We perform computational studies of static packings of a variety of nonspherical particles including circulo-lines, circulo-polygons, ellipses, asymmetric dimers, dumbbells, and others to determine which shapes form packings with fewer contacts than degrees of freedom (hypostatic packings) and which have equal numbers of contacts and degrees of freedom (isostatic packings), and to understand why hypostatic packings of nonspherical particles can be mechanically stable despite having fewer contacts than that predicted from naive constraint counting. To generate highly accurate force- and torque-balanced packings of circulo-lines and cir-polygons, we developed an interparticle potential that gives continuous forces and torques as a function of the particle coordinates. We show that the packing fraction and coordination number at jamming onset obey a masterlike form for all of the nonspherical particle packings we studied when plotted versus the particle asphericity A , which is proportional to the ratio of the squared perimeter to the area of the particle. Further, the eigenvalue spectra of the dynamical matrix for packings of different particle shapes collapse when plotted at the same A . For hypostatic packings of nonspherical particles, we verify that the number of "quartic" modes along which the potential energy increases as the fourth power of the perturbation amplitude matches the number of missing contacts relative to the isostatic value. We show that the fourth derivatives of the total potential energy in the directions of the quartic modes remain nonzero as the pressure of the packings is decreased to zero. In addition, we calculate the principal curvatures of the inequality constraints for each contact in circulo-line packings and identify specific types of contacts with inequality constraints that possess convex curvature. These contacts can constrain multiple degrees of freedom and allow hypostatic packings of nonspherical particles to be mechanically
The Role of Broken Cooper Pairs in Warm Nuclei
International Nuclear Information System (INIS)
Guttormsen, M.; Chankova, R.; Larsen, A.C.; Rekstad, J.; Siem, S.; Syed, N.U.H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.
2007-01-01
In order to understand warm nuclei and describe the underlying microscopic structure, entropy is measured for several even-even and odd-mass nuclei. Mid-shell nuclei show significant odd-even entropy differences interpreted as the single-particle entropy introduced by the valence nucleon. A method to extract critical temperatures for the pair breaking process is demonstrated. (author)
Systematics of light nuclei in a relativistic model
International Nuclear Information System (INIS)
Price, C.E.
1988-01-01
The results of relativistic mean field calculations for non-spherical nuclei are presented and discussed. The need for non-linear scalar meson self-couplings in order to describe the properties of s-d shell nuclei is emphasized along with the importance of self-consistency in calculations of magnetic moments of odd-mass nuclei. 16 refs., 3 figs., 2 tabs
Deformation effect on spectral statistics of nuclei
Sabri, H.; Jalili Majarshin, A.
2018-02-01
In this study, we tried to get significant relations between the spectral statistics of atomic nuclei and their different degrees of deformations. To this aim, the empirical energy levels of 109 even-even nuclei in the 22 ≤ A ≤ 196 mass region are classified as their experimental and calculated quadrupole, octupole, hexadecapole and hexacontatetrapole deformations values and analyzed by random matrix theory. Our results show an obvious relation between the regularity of nuclei and strong quadrupole, hexadecapole and hexacontatetrapole deformations and but for nuclei that their octupole deformations are nonzero, we have observed a GOE-like statistics.
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.
Nonspherical Microcapsules for Increased Core Content Volume Delivery Project
National Aeronautics and Space Administration — The goal of this project was to advance microencapsulation from the standard spherical microcapsule to a non-spherical, high-aspect ratio (HAR), elongated...
Effect of particle nonsphericity on bidirectional reflectance of cirrus clouds
Energy Technology Data Exchange (ETDEWEB)
Mishchenko, M.I.; Rossow, W.B.; Macke, A.; Lacis, A.A. [Goddard Institute for Space Studies, New York, NY (United States)
1996-04-01
This paper describes the use of the fractal ice particle method to study the differences in bidirectional reflectance caused by the differences in the single scattering phase functions of spherical water droplets and nonspherical ice crystals.
Turbulence Modulation by Non-Spherical Particles
DEFF Research Database (Denmark)
Mandø, Matthias
This study deals with the interaction between turbulence and non-spherical particles and represents an extension of the modeling framework for particleladen flows. The effect of turbulence on particles is commonly referred to as turbulent dispersion while the effect of particles on the carrier....... This study encompass an outlook on existing work, an experimental study, development of a numerical model and a case study advancing the modeling techniques for pulverized coal combustion to deal with larger non-spherical biomass particles. Firstly, existing knowledge concerning the motion of non......-spherical particles and turbulence modulation are outlined. A complete description of the motion of non-spherical particles is still lacking. However, evidence suggests that the equation of motion for a sphere only represent an asymptotical value for a more general, but yet unformulated, description of the motion...
DEM simulation of non-spherical granular segregation in hopper
Tao, He; Zhong, Wenqi; Jin, Baosheng; Ren, Bing
2013-07-01
Discrete element model (DEM) was developed to simulate the non-spherical particles such as cornshaped particle, ellipsoidal particle and cylinder particle. Multi-element particle model was used to describe the non-spherical particle that means the non-spherical particle was constructed by several overlapping spheres. And the simulation was validated by the experiment. In addition, the flow characteristic of particle discharging in the hopper was researched for different diameter ratio. The result shows that the segregation phenomenon emerged as described in the previous researcher. The effect of the particle shape, particle diameter ratio and particle density ratio on the segregation was studied. The result shows that there is big difference of segregation for different particle shape. The extent of segregation for ellipsoidal particles is the largest, and that of the spherical particles is the smallest. The segregation extent increases significantly with the diameter ratio. And varying particle density ratios do not affect the segregation results significantly.
Gravitational agglomeration of post-HCDA LMFBR aerosols: nonspherical particles
International Nuclear Information System (INIS)
Tuttle, R.F.; Loyalka, S.K.
1982-12-01
Aerosol behavior analysis computer programs have shown that temporal aerosol size distributions in nuclear reactor containments are sensitive to shape factors. This research investigates shape factors by a detailed theoretical analysis of hydrodynamic interactions between a nonspherical particle and a spherical particle undergoing gravitational collisions in an LMFBR environment. First, basic definitions and expressions for settling speeds and collisional efficiencies of nonspherical particles are developed. These are then related to corresponding quantities for spherical particles through shape factors. Using volume equivalent diameter as the defining length in the gravitational collision kernel, the aerodynamic shape factor, the density correction factor, and the gravitational collision shape factor, are introduced to describe the collision kernel for collisions between aerosol agglomerates. The Navier-Stokes equation in oblate spheroidal coordinates is solved to model a nonspherical particle and then the dynamic equations for two particle motions are developed. A computer program (NGCEFF) is constructed, and the dynamical equations are solved by Gear's method
Non-Spherical Microcapsules for Increased Core Content Volume Delivery
Oliva-Buisson, Yvette J.
2014-01-01
The goal of this project was to advance microencapsulation from the standard spherical microcapsule to a non-spherical, high-aspect ratio (HAR), elongated microcapsule. This was to be accomplished by developing reproducible methods of synthesizing or fabricating robust, non-spherical, HAR microcapsules. An additional goal of this project was to develop the techniques to the point where scale-up of these methods could be examined. Additionally, this project investigated ways to apply the microencapsulation techniques developed as part of this project to self-healing formulations.
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.)
International Nuclear Information System (INIS)
Pauling, L.; Robinson, A.B.
1975-01-01
Values of R, the radius of rotation of the rotating cluster, are calculated from the energy of the lowest 2 + level of even-even nuclei with the assumption that the cluster consists of p 2 or n 2 respectively, for N or P magic, and of a helion (α) for N or P differing from a magic number by +-2. The values as a function of A show a zigzag course, which is correlated with the polyspheron structure of the nuclei. If the mantle is not overcrowded the cluster glides over the surface of the mantle and the value of R increases by one spheron diameter, about 3.2 fm. At certain values of N a change in structure of the nucleus occurs, with increase in radius of the core by half a spheron diameter, permitting the cluster to drop back into the mantle, with decrease in R by half a spheron diameter. In the lanthanon region of permanent prolate deformation the rotating cluster is a polyhelion, containing the number of helions permitted by the difference between Z or N and the nearest magic number, and in the actinon region it contains all the nucleons beyond 208 Pb, with maximum p 10 n 16 . An explanation is given of the difference between these regions. (author)
Rolling and sliding between non-spherical particles
Zhao, Chuang; Li, Chengbo; Hu, Lin
2018-02-01
Besides normal and tangential forces, rolling and sliding are also important interactions of particles, and should be considered in the discrete element method. However, there are various definitions of rolling and sliding, some of which are quite different and even contradictory. On the premise of trying not to use definitions, the rolling and sliding velocities between non-spherical particles are derived, and satisfy the objectivity. The sliding and rolling velocities between spherical particles are included in the results as a special case. A rolling resistance model calculated by the rolling velocity is applied to simulate direct shear tests of non-spherical particles. In addition to coinciding with experiments, the shear curves also satisfy the rate independent theory. As a demonstration of the model's universality, the wave propagation in uniaxial compression tests is also simulated.
Single scattering from nonspherical Chebyshev particles: A compendium of calculations
Wiscombe, W. J.; Mugnai, A.
1986-01-01
A large set of exact calculations of the scattering from a class of nonspherical particles known as Chebyshev particles' has been performed. Phase function and degree of polarization in random orientation, and parallel and perpendicular intensities in fixed orientations, are plotted for a variety of particles shapes and sizes. The intention is to furnish a data base against which both experimental data, and the predictions of approximate methods, can be tested. The calculations are performed with the widely-used Extended Boundary Condition Method. An extensive discussion of this method is given, including much material that is not easily available elsewhere (especially the analysis of its convergence properties). An extensive review is also given of all extant methods for nonspherical scattering calculations, as well as of the available pool of experimental data.
Level density and thermal properties in rare earth nuclei
International Nuclear Information System (INIS)
Siem, S.; Schiller, A.; Guttormsen, M.; Hjorth-Jensen, M.; Melby, E.; Rekstad, J.
2000-01-01
The level density at low spin has been extracted for several nuclei in the rare earth region using the ( 3 He,α) reaction. Within the framework of the microcanonical ensemble, the entropy and the temperature of the nuclei are derived. The temperature curve shows bumps which are associated with the break up of Cooper pairs. The entropies of the even-even and even-odd nuclei have been compared. The nuclear heat capacity is deduced within the framework of the canonical ensemble and exhibits an S-formed shape as function of temperature. (author)
Merging black holes in non-spherical nuclear star clusters
Petrovich, Cristobal
2018-04-01
The Milky Way and a significant fraction of galaxies are observed to host a central Massive Black Hole (MBH) embedded in a non-spherical nuclear star cluster. I will discuss the orbital evolution of stellar binaries in these environments and argue that their merger rates are expected to be greatly enhanced when the effect from cluster potential is taken into account in the binary-MBH triple system. I will apply our results to compact-object binary mergers mediated by gravitational wave radiation and show that this merger channel can contribute significantly to the LIGO/Virgo detections.
Measurement of Turbulence Modulation by Non-Spherical Particles
DEFF Research Database (Denmark)
Mandø, Matthias; Rosendahl, Lasse
2010-01-01
at the centerline of the jet are carried out for mass loadings of 0.5, 1, 1.6 and particle sizes 880μm, 1350μm, 1820μm for spherical particles. For each non-spherical shape only a single size and loading are considered. The turbulence modulation of the carrier phase is found to highly dependent on the turbulence...... length scale, the mass loading, and the particle size and less dependent on the particle Reynolds number and the Stokes number for the investigated range. The results are compared with existing criteria and an expression is suggested to predict the turbulence modulation given the particle size...
Controlled electrosprayed formation of non-spherical microparticles
Jeyhani, Morteza; Mak, Sze Yi; Sammut, Stephen; Shum, Ho Cheung; Hwang, Dae Kun; Tsai, Scott S. H.
2017-11-01
Fabrication of biocompatible microparticles, such as alginate particles, with the possibility of controlling the particles' morphology in a high-throughput manner, is essential for pharmaceutical and cosmetic industries. Even though the shape of alginate particles has been shown to be an important parameter in controlling drug delivery, there are very limited manufacturing methods to produce non-spherical alginate microparticles in a high-throughput fashion. Here, we present a system that generates non-spherical biocompatible alginate microparticles with a tunable size and shape, and at high-throughput, using an electrospray technique. Alginate solution, which is a highly biocompatible material, is flown through a needle using a constant flow rate syringe pump. The alginate phase is connected to a high-voltage power supply to charge it positively. There is a metallic ring underneath the needle that is charged negatively. The applied voltage creates an electric field that forces the dispensing droplets to pass through the metallic ring toward the collection bath. During this migration, droplets break up to smaller droplets to dissipate their energy. When the droplets reach the calcium chloride bath, polymerization happens and solidifies the droplets. We study the effects of changing the distance from the needle to the bath, and the concentration of calcium chloride in the bath, to control the size and the shape of the resulting microparticles.
Interactions of non-spherical particles in simple flows
Niazi, Mehdi; Brandt, Luca; Costa, Pedro; Breugem, Wim-Paul
2015-11-01
The behavior of particles in a flow affects the global transport and rheological properties of the mixture. In recent years much effort has been therefore devoted to the development of an efficient method for the direct numerical simulation (DNS) of the motion of spherical rigid particles immersed in an incompressible fluid. However, the literature on non-spherical particle suspensions is quite scarce despite the fact that these are more frequent. We develop a numerical algorithm to simulate finite-size spheroid particles in shear flows to gain new understanding of the flow of particle suspensions. In particular, we wish to understand the role of inertia and its effect on the flow behavior. For this purpose, DNS simulations with a direct-forcing immersed boundary method are used, with collision and lubrication models for particle-particle and particle-wall interactions. We will discuss pair interactions, relative motion and rotation, of two sedimenting spheroids and show that the interaction time increases significantly for non-spherical particles. More interestingly, we show that the particles are attracted to each other from larger lateral displacements. This has important implications for collision kernels. This work was supported by the European Research Council Grant No. ERC-2013-CoG-616186, TRITOS, and by the Swedish Research Council (VR).
Scattering and Absorption by Nonspherical Particles in Planetary Atmospheres
West, Robert A.
2005-01-01
The atmospheres of Mars, the giant planets, and Titan all support populations of nonspherical particles. Analyses of observations of these atmospheres therefore rely on an understanding of the optical properties of nonspherical particles. We can glean information on particle size and composition from the wavelength dependence of the optical depth and from the shape of the forward peak of the scattering phase function. Additional information comes from polarization measurements which have been especially fruitful for Titan's haze. The Mars atmosphere contains mineral dust particles with effective radii near 1.6 micro meters, and water ice particles with radii between about 1 and 4 micro meters. The uppermost tropospheric hazes in Jupiter and Saturn are composed of ice crystals of ammonia, water and possibly traces of ammonium hydrosulfide, Methane ice and hydrogen sulfide ice are present in the atmospheres of Uranus and Neptune. Size estimation for these hazes in the giant planets is difficult, and even the expected spectral signatures are elusive, Titan's haze is both forward scattering and strongly polarized - a combination which points toward a fractal aggregate struc1.ure of 10 - 100 or more organic monomers whose radius is about 0.06 micro meters. Polar stratospheric hazes on Jupiter and Saturn also display this characteristic.
Light Scattering By Nonspherical Particles: Current Status and Challenging Issues
Mishchenko, Michael; Hansen, James E. (Technical Monitor)
2000-01-01
Quantitative analyses of remote sensing measurements of aerosols, clouds, precipitation, and particulate surfaces as well as computations of the Earth's radiation balance require detailed understanding of the interaction of small particles with light and other electromagnetic radiation. The convenient availability of the Lorenz-Mie theory has led to a widespread practice of treating all particles as if they were spheres. However, many natural and anthropogenic particles have nonspherical shapes, and the accumulated knowledge suggests that their scattering and radiative properties can be dramatically different from those of equivalent spheres. This presentation will summarize the recent significant progress achieved in the area of electromagnetic scattering by nonspherical particles and outline major problems that still await solution. The talk will cover the following specific topics: (1) comparison of most widely used exact and approximate theoretical techniques; (2) outline of laboratory and field measurement techniques; (3) compare theory and experiment; (4) need for a statistical approach in dealing with natural particles; (5) remote sensing and radiative transfer applications; and (6) major unsolved problems.
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.)
Elastic magnetic form factors of exotic nuclei
International Nuclear Information System (INIS)
Dong Tiekuang; Guo Yanqing; Ren Zhongzhou
2007-01-01
How to identify the orbital of the valence nucleon(s) of exotic nuclei is an important problem. The elastic magnetic electron scattering is an excellent probe to determine the valence structure of odd-A nuclei. The relativistic mean-field theory has been successfully applied to systematic studies of the elastic charge electron scattering from even-even exotic nuclei. The extension of this method to investigate the elastic magnetic electron scattering from odd-A exotic nuclei is a natural generalization. The experimental form factors of 17 O and 41 Ca are reproduced very well with the help of the spectroscopic factors which are introduced into the relativistic treatment of the magnetic electron scattering for the first time. The emphases are put on the magnetic form factors of 15,17,19 C, 23 O, 17 F, and 49,59 Ca calculated in the relativistic impulse approximation. Great differences have been found in the form factors of the same nucleus with different configurations. Therefore, the elastic magnetic electron scattering can be used to determine the orbital of the last nucleon of odd-A exotic nuclei. Our results can provide references for the electron scattering from exotic nuclei in the near future
Coherent Backscattering by Particulate Planetary Media of Nonspherical Particles
Muinonen, Karri; Penttila, Antti; Wilkman, Olli; Videen, Gorden
2014-11-01
The so-called radiative-transfer coherent-backscattering method (RT-CB) has been put forward as a practical Monte Carlo method to compute multiple scattering in discrete random media mimicking planetary regoliths (K. Muinonen, Waves in Random Media 14, p. 365, 2004). In RT-CB, the interaction between the discrete scatterers takes place in the far-field approximation and the wave propagation faces exponential extinction. There is a significant constraint in the RT-CB method: it has to be assumed that the form of the scattering matrix is that of the spherical particle. We aim to extend the RT-CB method to nonspherical single particles showing significant depolarization characteristics. First, ensemble-averaged single-scattering albedos and phase matrices of nonspherical particles are matched using a phenomenological radiative-transfer model within a microscopic volume element. Second, the phenomenologial single-particle model is incorporated into the Monte Carlo RT-CB method. In the ray tracing, the electromagnetic phases within the microscopic volume elements are omitted as having negligible lengths, whereas the phases are duly accounted for in the paths between two or more microscopic volume elements. We assess the computational feasibility of the extended RT-CB method and show preliminary results for particulate media mimicking planetary regoliths. The present work can be utilized in the interpretation of astronomical observations of asteroids and other planetary objects. In particular, the work sheds light on the depolarization characteristics of planetary regoliths at small phase angles near opposition. The research has been partially funded by the ERC Advanced Grant No 320773 entitled “Scattering and Absorption of Electromagnetic Waves in Particulate Media” (SAEMPL), by the Academy of Finland (contract 257966), NASA Outer Planets Research Program (contract NNX10AP93G), and NASA Lunar Advanced Science and Exploration Research Program (contract NNX11AB25G).
MISR Dark Water aerosol retrievals: operational algorithm sensitivity to particle non-sphericity
Directory of Open Access Journals (Sweden)
O. V. Kalashnikova
2013-08-01
Full Text Available The aim of this study is to theoretically investigate the sensitivity of the Multi-angle Imaging SpectroRadiometer (MISR operational (version 22 Dark Water retrieval algorithm to aerosol non-sphericity over the global oceans under actual observing conditions, accounting for current algorithm assumptions. Non-spherical (dust aerosol models, which were introduced in version 16 of the MISR aerosol product, improved the quality and coverage of retrievals in dusty regions. Due to the sensitivity of the retrieval to the presence of non-spherical aerosols, the MISR aerosol product has been successfully used to track the location and evolution of mineral dust plumes from the Sahara across the Atlantic, for example. However, the MISR global non-spherical aerosol optical depth (AOD fraction product has been found to have several climatological artifacts superimposed on valid detections of mineral dust, including high non-spherical fraction in the Southern Ocean and seasonally variable bands of high non-sphericity. In this paper we introduce a formal approach to examine the ability of the operational MISR Dark Water algorithm to distinguish among various spherical and non-spherical particles as a function of the variable MISR viewing geometry. We demonstrate the following under the criteria currently implemented: (1 Dark Water retrieval sensitivity to particle non-sphericity decreases for AOD below about 0.1 primarily due to an unnecessarily large lower bound imposed on the uncertainty in MISR observations at low light levels, and improves when this lower bound is removed; (2 Dark Water retrievals are able to distinguish between the spherical and non-spherical particles currently used for all MISR viewing geometries when the AOD exceeds 0.1; (3 the sensitivity of the MISR retrievals to aerosol non-sphericity varies in a complex way that depends on the sampling of the scattering phase function and the contribution from multiple scattering; and (4 non-sphericity
Relativistic mean field theory for unstable nuclei
International Nuclear Information System (INIS)
Toki, Hiroshi
2000-01-01
We discuss the properties of unstable nuclei in the framework of the relativistic mean field (RMF) theory. We take the RMF theory as a phenomenological theory with several parameters, whose form is constrained by the successful microscopic theory (RBHF), and whose values are extracted from the experimental values of unstable nuclei. We find the outcome with the newly obtained parameter sets (TM1 and TMA) is promising in comparison with various experimental data. We calculate systematically the ground state properties of even-even nuclei up to the drip lines; about 2000 nuclei. We find that the neutron magic shells (N=82, 128) at the standard magic numbers stay at the same numbers even far from the stability line and hence provide the feature of the r-process nuclei. However, many proton magic numbers disappear at the neutron numbers far away from the magic numbers due to the deformations. We discuss how to describe giant resonances for the case of the non-linear coupling terms for the sigma and omega mesons in the relativistic RPA. We mention also the importance of the relativistic effect on the spin observables as the Gamow-Teller strength and the longitudinal and transverse spin responses. (author)
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
Correlating radii and electric monopole transitions of atomic nuclei.
Zerguine, S; Van Isacker, P; Bouldjedri, A; Heinze, S
2008-07-11
A systematic analysis of the spherical-to-deformed shape phase transition in even-even rare-earth nuclei from 58Ce to 74W is carried out in the framework of the interacting boson model. These results are then used to calculate nuclear radii and electric monopole (E0) transitions with the same effective operator. The influence of the hexadecapole degree of freedom (g boson) on the correlation between radii and E0 transitions thus established is discussed.
Odd A nuclei description in terms of boson and fermion interacting model
International Nuclear Information System (INIS)
Vergnes, M.
1986-01-01
The odd-A nuclei are considered in the IBFM model to consist of an even-even core (described by the interacting boson model) and of a few fermions. In the general case the Hamiltonian is numerically diagonalized after a number of approximations. The results of a typical calculation are compared to experiment. In special cases it is possible to obtain analytical expressions for experimentally measurable quantities. These limiting cases are the Bose-Fermi symmetries for odd-A nuclei and the supersymmetries describing simultaneously both even-even and odd-A nuclei. The Bose-Fermi Spin (6) and the U(6/4) supersymmetry models are described in details and compared to experiments. The more recent ''multi-j'' U(6/12) supersymmetry models, the extension of supersymmetry to the odd-odd nuclei and the generalized supersymmetry, are only briefly discussed [fr
On the motion of non-spherical particles at high Reynolds number
DEFF Research Database (Denmark)
Mandø, Matthias; Rosendahl, Lasse
2010-01-01
This paper contains a critical review of available methodology for dealing with the motion of non-spherical particles at higher Reynolds numbers in the Eulerian- Lagrangian methodology for dispersed flow. First, an account of the various attempts to classify the various shapes and the efforts...... towards finding a universal shape parameter is given and the details regarding the significant secondary motion associated with non-spherical particles are outlined. Most investigations concerning large non-spherical particles to date have been focused on finding appropriate correlations of the drag...... coefficient for specific shapes either by parameter variation or by using shape parameters. Particular emphasis is here placed on showing the incapability of one-dimensional shape parameters to predict the multifaceted secondary motion associated with non-spherical particles. To properly predict secondary...
Remarkable long-range-systematic in the binding energies of α-nuclei. II
International Nuclear Information System (INIS)
Gross, D.H.E.
2003-01-01
In this Letter I present further data that show the remarkable evidence for the existence of an α-cluster structure in the ground states of even-even N=Z nuclei. Such a remarkable systematic was observed 20 years ago Gross and Nemes [Phys. Lett. B 130 (1983) 131] for these nuclei at A≤72 and is extended here up to A=100
Basic equations for odd spherical nuclei in the quasiparticle-phonon nuclear model
International Nuclear Information System (INIS)
Dao Tien Khoa; Vdovin, A.I.; Voronov, V.V.
1984-01-01
The system of basic equations in the general form is obtained for odd spherical nuclei within the quasiparticle-model. The anharmonics of vibrations of even-even core and Pauli principle corrections are included into these equations. It has been shown that the derived system of equations contains all versions of approximate equations used in the calculation within the quasiparticle-phonon model
Preduction of transport properties of gases using classical nonspherical models
International Nuclear Information System (INIS)
Verlin, J.D.
1976-01-01
The general formulation of the classical kinetic theory, which is needed to predict transport properties of gases in situations where the hydrodynamic equations are valid, is reviewed. A rigid convex model of tetrahedral symmetry is used to predict the Senftleben-Beenakker effect of a static magnetic field on the thermal conductivity and viscosity of pure CH 4 , CD 4 and CF 4 . The parameters of the model are optimized and are found to assume physically reasonable values. The calculations agree with experiment to a degree comparable to that of similar work on diatomic molecules. A generalized scattering cross section, γ, is defined which can be evaluated exactly for the limiting cases of a spherical soft potential and rigid ovaloids. For a general soft nonspherical interaction of the Kihara type, a suitable approximation for the momentum dependence is made with the following attributes: γ reduces to the form for soft sphere and rigid ovaloid in the limits and the resulting matrix elements of the collision operator can be written in terms of the familiar Ω* integrals. This formulation is used to investigate thermal diffusion in binary isotopic mixtures of CO. Calculations are made in an 80 0 K to 300 0 K range which includes the inversion temperatures for all mixtures studied. Thermal conductivity and diffusion coefficients of CO are also calculated. The parameters of the model can be adjusted to account for the major features of the experimental data. The physical significance of the parameters is discussed
Packing Nonspherical Particles: All Shapes Are Not Created Equal
Torquato, Salvatore
2012-02-01
Over the past decade there has been increasing interest in the effects of particle shape on the characteristics of dense particle packings, since deviations from sphericity can lead to more realistic models of granular media, nanostructured materials, and tissue architecture. It is clear the that the broken rotational symmetry of a nonspherical particle is a crucial aspect in determining its resulting packing characteristics, but given the infinite variety of possible shapes (ellipsoids, superballs, regular and irregular polyhedra, etc.) it is desirable to formulate packing organizing principles based the particle shape. Such principles are beginning to be elucidated; see Refs. 1 and 2 and references therein. Depending upon whether the particle has central symmetry, inequivalent principle axes, and smooth or flat surfaces, we can describe the nature of its densest packing (which is typically periodic) as well as its disordered jammed states (which may or may not be isostatic). Changing the shape of a particle can dramatically alter its packing attributes. This tunability capability via particle shape could be used to tailor many-particle systems (e.g., colloids and granular media) to have designed crystal, liquid and glassy states. [4pt] [1] S. Torquato and F. H. Stillinger, ``Jammed Hard-Particle Packings: From Kepler to Bernal and Beyond," Rev. Modern Phys. 82, 2633 (2010). [0pt] [2] Y. Jiao and S. Torquato, Communication: ``A Packing of Truncated Tetrahedra That Nearly Fills All of Space and its Melting Properties," J. Chem. Phys. 135, 151101 (2011).
Equations of state of nonspherical fluids by spherical intermolecular potentials
International Nuclear Information System (INIS)
Bastea, S; Ree, F H
1999-01-01
The equilibrium properties of anisotropic molecular fluids can be in principle calculated in a statistical mechanics framework, but the theory is generally too cumbersome for many practical applications. Fortunately, at high densities and temperatures the anisotropy can be averaged-out by means of a density and temperature independent potential (the median) that produces reliable thermodynamics[1,2]. The proposal of Shaw and Johnson[1], which turns out to be the so-called median potential[2], is very successful in predicting the thermodynamics of simple fluids such as N(sub 2) and CO(sub 2) at reasonable high pressures and temperatures[3]. Lebowitz and Percus[2] pointed out some time ago that the success of this approximation could perhaps be understood in terms of a simple theory that treats the asphericity as a perturbation. The median appears to be the best choice for hard nonspherical potential[4], which may explain its success for fluids at high densities, where the hard core contribution is known to be dominant
Shock waves from non-spherically collapsing cavitation bubbles
Supponen, Outi; Obreschkow, Danail; Farhat, Mohamed
2017-11-01
Combining simultaneous high-speed imaging and hydrophone measurements, we uncover details of the multiple shock wave emission from laser-induced cavitation bubbles collapsing in a non-spherical way. For strongly deformed bubbles collapsing near a free surface, we identify the distinct shock waves caused by the jet impact onto the opposite bubble wall and by the individual collapses of the remaining bubble segments. The energy carried by each of these shocks depends on the level of bubble deformation, quantified by the anisotropy parameter ζ, the dimensionless equivalent of the Kelvin impulse. For jetting bubbles, at ζ hammer pressure is found to be the most energetic shock. Through statistical analysis of the experimental data and theoretical derivations, and by comparing bubbles deformed by different sources (variable gravity achieved on parabolic flights, and neighboring free and rigid surfaces), we find that the shock peak pressure may be approximated as the jet impact-induced water hammer as ph = 0.45 (ρc2 Δp) 1 / 2ζ-1 .
Heat transfer rate within non-spherical thick grains
Directory of Open Access Journals (Sweden)
Huchet Florian
2017-01-01
Full Text Available The prediction of the internal heat conduction into non-spherical thick grains constitutes a significant issue for physical modeling of a large variety of application involving convective exchanges between fluid and grains. In that context, the present paper deals with heat rate measurements of various sizes of particles, the thermal sensors being located at the interface fluid/grain and into the granular materials. Their shape is designed as cuboid in order to control the surface exchanges. In enclosed coneshaped apparatus, a sharp temperature gradient is ensured from a hot source releasing the air stream temperature equal to about 400°C. Two orientations of grain related to the air stream are considered: diagonally and straight arrangements. The thermal diffusivity of the grains and the Biot numbers are estimated from an analytical solution established for slab. The thermal kinetics evolution is correlated to the sample granular mass and its orientation dependency is demonstrated. Consequently, a generalized scaling law is proposed which is funded from the effective area of the heat transfer at the grain-scale, the dimensionless time being defined from the calculated diffusional coefficients.
Deformation and shape coexistence in medium mass nuclei
International Nuclear Information System (INIS)
Meyer, R.A.
1985-01-01
Emerging evidence for deformed structures in medium mass nuclei is reviewed. Included in this review are both nuclei that are ground state symmetric rotors and vibrational nuclei where there are deformed structures at excited energies (shape coexistence). For the first time, Nilsson configurations in odd-odd nuclei within the region of deformation are identified. Shape coexistence in nuclei that abut the medium mass region of deformation is also examined. Recent establishment of a four-particle, four-hole intruder band in the double subshell closure nucleus 96 Zr 56 is presented and its relation to the nuclear vibron model is discussed. Special attention is given to the N=59 nuclei where new data have led to the reanalysis of 97 Sr and 99 Zr and the presence of the [404 9/2] hole intruder state as isomers in these nuclei. The low energy levels of the N=59 nuclei from Z=38 to 50 are compared with recent quadrupole-phonon model calculations that can describe their transition from near-rotational to single closed shell nuclei. The odd-odd N=59 nuclei are discussed in the context of coexisting shape isomers based on the (p[303 5/2]n[404 9/2])2 - configuration. Ongoing in-beam (t,p conversion-electron) multiparameter measurements that have led to the determination of monopole matrix elements for even-even 42 Mo nuclei are presented, and these are compared with initial estimates using IBA-2 calculations that allow mixing of normal and cross subshell excitations. Lastly, evidence for the neutron-proton 3 S 1 force's influence on the level structure of these nuclei is discussed within the context of recent quadrupole-phonon model calculations. (Auth.)
Particle-rotation coupling in atomic nuclei
International Nuclear Information System (INIS)
Almberger, J.
1980-01-01
Recently an increased interest in the rotational nuclei has been spurred by the new experimental high-spin activities and by the possibilities for lower spins to interpret an impressive amount of experimental data by some comparatively simple model calculations. The author discusses the particle modes of excitation for rotational nuclei in the pairing regime where some puzzles in the theoretical description remain to be resolved. A model comparison is made between the particle-rotor and cranking models which have different definitions of the collective rotation. The cranking model is found to imply a smaller value of the quasiparticle spin alignment than the particle-rotor model. Rotational spectra for both even and odd nuclei are investigated with the use of the many-BCS-quasiparticles plus rotor model. This model gives an accurate description of the ground and S-bands in many even-even rare-earth nuclei. However, the discrepancies for odd-A nuclei between theory and experiments point to the importance of additional physical components. Therefore the rotationally induced quadrupole pair field is considered. This field has an effect on the low spin states in odd-A nuclei, but is not sufficient to account for the experimental data. Another topic considered is the interaction matrix element in crossings for given spin between quasiparticle rotational bands. The matrix elements are found to oscillate as a function of the number of particles, thereby influencing the sharpness of the backbending. Finally the low-spin continuation of the S-band is studied and it is shown that such states can be populated selectively by means of one-particle pickup reactions involving high angular momentum transfer. (Auth.)
International Nuclear Information System (INIS)
Clark, R.; Wadsworth, B.
1998-01-01
Magnetic rotation is a new phenomenon that is forcing physicists to rethink their understanding of what goes on inside the nucleus The rotation of quantum objects has a long and distinguished history in physics. In 1912 the Danish scientist Niels Bjerrum was the first to recognize that the rotation of molecules is quantized. In 1938 Edward Teller and John Wheeler observed similar features in the spectra of excited nuclei, and suggested that this was caused by the nucleus rotating. But a more complete explanation had to wait until 1951, when Aage Bohr (the son of Niels) pointed out that rotation was a consequence of the nucleus deforming from its spherical shape. We owe much of our current understanding of nuclear rotation to the work of Bohr and Ben Mottelson, who shared the 1975 Nobel Prize for Physics with James Rainwater for developing a model of the nucleus that combined the individual and collective motions of the neutrons and protons inside the nucleus. What makes it possible for a nucleus to rotate? Quantum mechanically, a perfect sphere cannot rotate because it appears the same when viewed from any direction and there is no point of reference against which its change in position can be detected. To see the rotation the spherical symmetry must be broken to allow an orientation in space to be defined. For example, a diatomic molecule, which has a dumbbell shape, can rotate about the two axes perpendicular to its axis of symmetry. A quantum mechanical treatment of a diatomic molecule leads to a very simple relationship between rotational energy, E, and angular momentum. This energy is found to be proportional to J(J + 1), where J is the angular momentum quantum number. The molecule also has a magnetic moment that is proportional to J. These concepts can be applied to the atomic nucleus. If the distribution of mass and/or charge inside the nucleus becomes non-spherical then the nucleus will be able to rotate. The rotation is termed ''collective'' because many
The pygmy dipole resonance in neutron-rich nuclei
International Nuclear Information System (INIS)
Hung, Nguyen Quang; Kiet, Hoang Anh Tuan; Duc, Huynh Ngoc; Chuong, Nguyen Thi
2016-01-01
The pygmy dipole resonance (PDR), which has been observed via the enhancement of the electric dipole strength E 1 of atomic nuclei, is studied within a microscopic collective model. The latter employs the Hartree-Fock (HF) method with effective nucleon-nucleon interactions of the Skyrme types plus the random-phase approximation (RPA). The results of the calculations obtained for various even-even nuclei such as 16-28 O, 40-58 Ca, 100-120 Sn, and 182-218 Pb show that the PDR is significantly enhanced when the number of neutrons outside the stable core of the nucleus is increased, that is, in the neutron-rich nuclei. As the result, the relative ratio between the energy weighted sum of the strength of the PDR and that of the GDR (giant dipole resonance) does not exceed 4%. The collectivity of the PDR and GDR states will be also discussed. (paper)
Global systematics of nuclear observables in odd-A nuclei
International Nuclear Information System (INIS)
Bucurescu, D.
1996-01-01
Different correlations between observables related to the unique parity orbital structures in the odd-A nuclei are studied. It is shown that the correlations between excitation energies within the unique parity orbital quasibands allow a tripartite classification of the evolution of the nuclear structure, similar to that observed in the adjacent even-even nuclei: all nuclei can be assigned to three different regimes, the precollective, anharmonic vibrator and strong coupling, respectively, interconnected by fast, critical phase-like transitions. It is shown that both an index which characterizes the signature splitting, and the B(E2) values within the quasibands can be organized in terms of a valence correlation scheme. (author)
Analytical transform techniques to retrieve non-spherical particle size distribution
International Nuclear Information System (INIS)
Zhao, Jian-Qi; Li, Jiangnan
2013-01-01
The measurement of particle size distribution (PSD) from the extinction spectra is a challenging problem, especially for non-spherical particles. In this work, the analytical transform techniques are developed to retrieve PSD from the measured scattering data for a variety of shapes of non-spherical particle including spheroids, cuboids, triangular prisms, hexagonal prisms and elliptical cylinders. In the retrieve calculation, all particles have aligned orientations and their extinction cross sections can be adequately calculated by using the anomalous diffraction theory (ADT). It is shown that for each type of the considered non-spherical particles, there exists an ADT transform pair between the size distribution and the extinction spectrum. The inverse formula of PSD from the related ADT transform is therefore established. This result provides a new approach to the solution of the inversion problem and has the potential to be used in finding solutions for more complicated particle shapes. It is found that the solution of inverse scattering for absorbing particles can be simplified to a particular solution in which the character of absorption becomes no longer present. For spheroids, triangular prisms, and elliptical cylinders, the retrieved PSD and the corresponding true PSD always belong to one family of function, due to the scaling relation. Therefore an improper choice of inversion parameters does not significantly affect the type of mode of PSD in a retrieval process. -- Highlights: •Analytical schemes for inversion of non-spherical particle size distribution. •Intuitive inverse formulas and novel ADT transform fairs for non-spherical particles. •Useful scaling relations in retrievals for non-spherical particles
Extension of the consistent Q formalism to odd-A nuclei in the W-Pt region
Energy Technology Data Exchange (ETDEWEB)
Warner, D.D.; Van Isacker, P.; Jolie, J.; Bruce, A.M.
1984-01-01
It is shown that the approach of the Consistent Q Formalism, which has proved successful in the Interacting Boson Model description of even-even nuclei, can be extended to odd A nuclei within the framework of the Interacting Boson-Fermion Model. The proposed method describes the transition between the SU(3) and O(6) symmetry limits of the U(6/12) boson fermion group, and can be applied to the odd neutron W, Os, Pt nuclei. As in the even-even case, a number of parameter-free predictions emerge for the transitional region concerning energies, B(E2) values and also single particle structure factors, and some of these are compared to existing data for the odd Os nuclei. 15 references.
Fusion excitation functions involving transitional nuclei
Energy Technology Data Exchange (ETDEWEB)
Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others
1995-08-01
Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.
Effective field theory for triaxially deformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Chen, Q.B. [Technische Universitaet Muechen, Physik-Department, Garching (Germany); Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing (China); Kaiser, N. [Technische Universitaet Muechen, Physik-Department, Garching (Germany); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Institute for Advanced Simulation, Institut fuer Kernphysik, Juelich Center for Hadron Physics and JARA-HPC, Forschungszentrum Juelich, Juelich (Germany); Meng, J. [Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing (China); Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); University of Stellenbosch, Department of Physics, Stellenbosch (South Africa)
2017-10-15
Effective field theory is generalized to investigate the rotational motion of triaxially deformed even-even nuclei. The Hamiltonian for the triaxial rotor is obtained up to next-to-leading order within the effective field theory formalism. Its applicability is examined by comparing with a five-dimensional rotor-vibrator Hamiltonian for the description of the energy spectra of the ground state and γ band in Ru isotopes. It is found that by taking into account the next-to-leading order corrections, the ground state band in the whole spin region and the γ band in the low spin region are well described. The deviations for high-spin states in the γ bands point towards the importance of including vibrational degrees of freedom in the effective field theory formulation. (orig.)
Friction factor for water flow through packed beds of spherical and non-spherical particles
Directory of Open Access Journals (Sweden)
Kaluđerović-Radoičić Tatjana
2017-01-01
Full Text Available The aim of this work was the experimental evaluation of different friction factor correlations for water flow through packed beds of spherical and non-spherical particles at ambient temperature. The experiments were performed by measuring the pressure drop across the bed. Packed beds made of monosized glass spherical particles of seven different diameters were used, as well as beds made of 16 fractions of quartz filtration sand obtained by sieving (polydisperse non-spherical particles. The range of bed voidages was 0.359–0.486, while the range of bed particle Reynolds numbers was from 0.3 to 286 for spherical particles and from 0.1 to 50 for non-spherical particles. The obtained results were compared using a number of available literature correlations. In order to improve the correlation results for spherical particles, a new simple equation was proposed in the form of Ergun’s equation, with modified coefficients. The new correlation had a mean absolute deviation between experimental and calculated values of pressure drop of 9.04%. For non-spherical quartz filtration sand particles the best fit was obtained using Ergun’s equation, with a mean absolute deviation of 10.36%. Surface-volume diameter (dSV necessary for correlating the data for filtration sand particles was calculated based on correlations for dV = f(dm and Ψ = f(dm. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172022
Nuclei far from stability. Individual and collective excitations at low energy
International Nuclear Information System (INIS)
Meyer, M.
1984-01-01
The low energy structure of exotic nuclei is discussed in terms of self-consistent microscopic models. The experimental striking features of the spectroscopy of these nuclei are briefly surveyed and the schematic steps performed to obtain from effective N-N interactions their spectroscopic properties are presented. Their saturation and deformation properties are given by the Hartree-Fock approximation (HF). Then it is shown how to describe the dynamics of even-even exotic nuclei excited states by solving the complete Bohr Hamiltonian, built microscopically using the HF approximation and the adiabatic limit (and its derivatives) of the time-dependent HF approximation (ATDHF). The structure of odd and doubly odd nuclei is discussed in the framework of the unified model, ie the microscopic rotor + quasiparticles model. Finally possible future directions of experimental research concerning exotic nuclei are described and improvements or new theoretical approaches discussed [fr
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
Deformed Brueckner-Hartree-Fock calculation for light nuclei
Braley, R. C.; Ford, W. F.; Becker, R. L.; Patterson, M. R.
1971-01-01
For the first time the Brueckner-Hartree-Fock (BHF) method was applied to nuclei whose intrinsic structure is nonspherical. One aim was to investigate whether the energy dependent reaction matrix calculated from a realistic nucleon-nucleon interaction leads to deformations similar to, or different from, those obtained from energy independent interactions in Hartree-Fock (HF) calculations. Reaction matrix elements were calculated as a function of starting energy for the Hamada-Johnston interaction, using a Pauli operator appropriate to O-16 and a shifted oscillator spectrum for virtual excited states. Binding energies, single-particle energies, radii, and shape deformations of the intrinsic state in unrenormalized as well as renormalized BHF are discussed and compared with previous HF studies. Results are presented for C-12, O-16, and Ne-20.
Simulation of statistical γ-spectra of highly excited rare earth nuclei
International Nuclear Information System (INIS)
Schiller, A.; Munos, G.; Guttormsen, M.; Bergholt, L.; Melby, E.; Rekstad, J.; Siem, S.; Tveter, T.S.
1997-05-01
The statistical γ-spectra of highly excited even-even rare earth nuclei are simulated applying appropriate level density and strength function to a given nucleus. Hindrance effects due to K-conservation are taken into account. Simulations are compared to experimental data from the 163 Dy( 3 He,α) 162 Dy and 173 Yb( 3 He,α) 172 Yb reactions. The influence of the K quantum number at higher energies is discussed. 21 refs., 7 figs., 2 tabs
Scattering from Model Nonspherical Particles Theory and Applications to Environmental Physics
Borghese, Ferdinando; Saija, Rosalba
2007-01-01
The scattering of electromagnetic radiation by nonspherical particles has become an increasingly important research topic over the past 20 years. Instead of handling anisotropic particles of arbitrary shape, the authors consider the more amenable problem of aggregates of spherical particles. This is often a very satisfactory approach as the optical response of nonspherical particles depends more on their general symmetry and the quantity of refractive material than on the precise details of their shape. The book addresses a wide spectrum of applications, ranging from scattering properties of water droplets containing pollutants, atmospheric aerosols and ice crystals to the modeling of cosmic dust grains as aggregates. In this extended second edition the authors have encompassed all the new topics arising from their recent studies of cosmic dust grains. Thus many chapters were deeply revised and new chapters were added. The new material spans The description of the state of polarization of electromagnetic wave...
Nemchinsky, V.; Khrabry, A.
2018-02-01
Trajectories of a polarizable species (atoms or molecules) in the vicinity of a negatively charged nanoparticle (at a floating potential) are considered. The atoms are pulled into regions of strong electric field by polarization forces. The polarization increases the deposition rate of the atoms and molecules at the nanoparticle. The effect of the non-spherical shape of the nanoparticle is investigated by the Monte Carlo method. The shape of the non-spherical nanoparticle is approximated by an ellipsoid. The total deposition rate and its flux density distribution along the nanoparticle surface are calculated. It is shown that the flux density is not uniform along the surface. It is maximal at the nanoparticle tips.
Inamuro, Takaji; Hayashi, Hirofumi; Koshiyama, Masahiro
2008-11-01
The lattice Boltzmann method (LBM) for multicomponent immiscible fluids is applied to the simulations of solid-fluid mixture flows including spherical and nonspherical particles in a square pipe. A spherical solid particle is modeled by a droplet with strong interfacial tension and large viscosity, and consequently there is no need to track the moving solid-liquid boundary explicitly. Nonspherical (discoid and biconcave discoid) solid particles are made by applying artificial forces to the spherical droplet. It is found that spherical particles move around stable positions between the wall and the center of the pipe. On the other hand, a biconcave discoid particle moves along a helical path around the center of the pipe with periodic oscillations in its orientation. The radius of the helical path and the polar angle of the orientation increase as the hollow of the concave becomes larger.
International Nuclear Information System (INIS)
Beurtey, R.
1975-01-01
The present situation of the theoretical studies and experimental material concerning the potential presence of virtual nucleon excited states (isobars) in nuclei is reported. Three particular aspects are examined: the theoretical work devoted to the isobar content of nuclei (especially deuteron), the experimental material concerning isobar exchange and the attempts to obtain a direct evidence for such objects in the deuteron (spectator method) [fr
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)
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
Nuclear structure of s-d shell nuclei: what is new?
International Nuclear Information System (INIS)
Shanmugam, G.
1995-01-01
In this paper the shape evolution of the even-even s-d shell nuclei with temperature and spin is studied using Landau theory of phase transitions. The most important thermal fluctuations are incorporated in this study. The ground state pairing is also included in the calculations. Both the summation and Strutinsky methods are used for extracting the Landau constants. Both yield qualitatively similar results. To conclude, Landau theory of phase transitions can be effectively and economically used to study the structure of excited s-d shell nuclei. 10 refs., 2 tabs., 8 figs
The drag and lift of different non-spherical particles from low to high Re
Sanjeevi, Sathish K. P.; Padding, Johan
2017-11-01
The present work investigates a simplified drag and lift model that can be used for different non-spherical particles. The flow around different non-spherical particles is studied using a multi-relaxation-time lattice Boltzmann method. We compute the mean drag coefficient CD , ϕ at different incident angles ϕ for a wide range of Reynolds numbers (Re). We show that the sine-squared drag law CD , ϕ =CD , ϕ =0° +(CD , ϕ =90° -CD , ϕ =0°) sin2 ϕ holds up to large Reynolds numbers Re = 2000 . The sine-squared dependence of CD occurs at Stokes flow (very low Re) due to linearity of the flow fields. We explore the physical origin behind the sine-squared law at high Re , and reveal that surprisingly, this does not occur due to linearity of flow fields. Instead, it occurs due to an interesting pattern of pressure distribution contributing to the drag, at higher Re , for different incident angles. Similarly, we find that the equivalent theoretical equation of lift coefficient CL can provide a decent approximation, even at high Re , for elongated particles. Such a drag and lift law valid at high Re is very much useful for Euler-Lagrangian fluidization simulations of the non-spherical particles. European Research Council (ERC) consolidator Grant scheme, Contract No. 615096 (NonSphereFlow).
Structure of even-even beryllium isotopes studied by AMD plus GCM method
Czech Academy of Sciences Publication Activity Database
Thiamová, Gabriela; Itagaki, N.; Otsuka, T.
2004-01-01
Roč. 54, č. 7 (2004), s. 739-747 ISSN 0011-4626 Institutional research plan: CEZ:AV0Z1048901 Keywords : antisymmetrized molecular dynamics Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.292, year: 2004
The influence of the shell closure on the microscopic structure of even-even Hg isotopes
International Nuclear Information System (INIS)
Burghardt, A.J.C.
1989-01-01
Muonic X-ray data were obtained for 198 200 202 204 Hg at high-intensity muon-beam facility of SIN and an electron-scattering study was performed on 204 Hg with the 500 MeV, high-resolution electron-scattering facility of NIKHEF-K in a q-range from 0.4 to 2.9 fm -1 . The combined analysis of the elastic electron-scattering and muonic X-ray data has yielded the ground-state charge distribution of 204 Hg. Hartree-Fock calculations with four different interactions, with and without the inclusion of pairing correlations, are compared to this experimental result. The charge-density difference between 206 Pb (determined elsewhere) and 204 Hg is then used ot investigate the filling of the last proton orbit before the Z=82 shell closure, the 3s 1/2 orbit. The interpretation of this difference, also in terms of Hartree-Fock calculations, is discussed in conjunction with the earlier study of Frois et al. concerning 206 Pb and 205 Tl. Many excited states have been observed in the spectra of 204 Hg. The experimental excitation energies and the spins and parities assigned to a number of states are presented. From the cross-section data for these states transition charge distributions have been extracted. Shell-model predictions are compared with the observed level scheme and the shell-model calculation performed by Poppelier is used to interpret transition charge distributions of six states. 101 refs.; 32 figs.; 41 figs
Neutron scattering investigation of the deformation in even-even tungsten isotopes
International Nuclear Information System (INIS)
Delaroche, J.P.; Haouat, G.; Shamu, R.; Lachkar, J.; Patin, M.; Sigaud, J.; Chardine, J.
1977-01-01
Nuclear deformation in the rare earth region, using neutron scattering, has been studied for the tungsten isotopes. Elastic scattering and inelastic scattering cross sections for the first and second excited state of 182 W, 183 W, 184 W, 186 W have been measured at an incident neutron energy of 3.40 MeV. The even isotope data were analysed using the coupled channel optical model together with the statistical model. The deformation parameters β 2 and β 4 were obtained from this analysis and compared to values deduced from nuclear structure studies [fr
Random interactions, isospin, and the ground states of odd-A and odd-odd nuclei
International Nuclear Information System (INIS)
Horoi, Mihai; Volya, Alexander; Zelevinsky, Vladimir
2002-01-01
It was recently shown that the ground state quantum numbers of even-even nuclei have a high probability to be reproduced by an ensemble of random but rotationally invariant two-body interactions. In the present work we extend these investigations to odd-A and odd-odd nuclei, considering in particular the isospin effects. Studying the realistic shell model as well as the single-j model, we show that random interactions have a tendency to assign the lowest possible total angular momentum and isospin to the ground state. In the sd shell model this reproduces correctly the isospin but not the spin quantum numbers of actual odd-odd nuclei. An odd-even staggering effect in probability of various ground state quantum numbers is present for even-even and odd-odd nuclei, while it is smeared out for odd-A nuclei. The observed regularities suggest the underlying mechanism of bosonlike pairing of fermionic pairs in T=0 and T=1 states generated by the off-diagonal matrix elements of random interactions. The relation to the models of random spin interactions is briefly discussed
International Nuclear Information System (INIS)
Mansour, N.; Bayomy, T.; Awwad, Z.
1990-01-01
We will present results on an collective ΔI = 2 ground band level sequence in the spherical six-valence-particle nucleus 152 Dy and the variation of shapes for nuclei in the N = 88 to 92 transitional region. Finally, we will present results for some even-even nuclei without any backbending behaviour, showed a clear backbending in the diagram of 2Φ/(h/2π) 2 versus (hw/2π) 2 . (author)
Alpha-cluster preformation factor within cluster-formation model for odd-A and odd-odd heavy nuclei
Saleh Ahmed, Saad M.
2017-06-01
The alpha-cluster probability that represents the preformation of alpha particle in alpha-decay nuclei was determined for high-intensity alpha-decay mode odd-A and odd-odd heavy nuclei, 82 CSR) and the hypothesised cluster-formation model (CFM) as in our previous work. Our previous successful determination of phenomenological values of alpha-cluster preformation factors for even-even nuclei motivated us to expand the work to cover other types of nuclei. The formation energy of interior alpha cluster needed to be derived for the different nuclear systems with considering the unpaired-nucleon effect. The results showed the phenomenological value of alpha preformation probability and reflected the unpaired nucleon effect and the magic and sub-magic effects in nuclei. These results and their analyses presented are very useful for future work concerning the calculation of the alpha decay constants and the progress of its theory.
Evaluation of advanced automatic PET segmentation methods using nonspherical thin-wall inserts
International Nuclear Information System (INIS)
Berthon, B.; Marshall, C.; Evans, M.; Spezi, E.
2014-01-01
Purpose: The use of positron emission tomography (PET) within radiotherapy treatment planning requires the availability of reliable and accurate segmentation tools. PET automatic segmentation (PET-AS) methods have been recommended for the delineation of tumors, but there is still a lack of thorough validation and cross-comparison of such methods using clinically relevant data. In particular, studies validating PET segmentation tools mainly use phantoms with thick plastic walls inserts of simple spherical geometry and have not specifically investigated the effect of the target object geometry on the delineation accuracy. Our work therefore aimed at generating clinically realistic data using nonspherical thin-wall plastic inserts, for the evaluation and comparison of a set of eight promising PET-AS approaches. Methods: Sixteen nonspherical inserts were manufactured with a plastic wall of 0.18 mm and scanned within a custom plastic phantom. These included ellipsoids and toroids derived with different volumes, as well as tubes, pear- and drop-shaped inserts with different aspect ratios. A set of six spheres of volumes ranging from 0.5 to 102 ml was used for a baseline study. A selection of eight PET-AS methods, written in house, was applied to the images obtained. The methods represented promising segmentation approaches such as adaptive iterative thresholding, region-growing, clustering and gradient-based schemes. The delineation accuracy was measured in terms of overlap with the computed tomography reference contour, using the dice similarity coefficient (DSC), and error in dimensions. Results: The delineation accuracy was lower for nonspherical inserts than for spheres of the same volume in 88% cases. Slice-by-slice gradient-based methods, showed particularly lower DSC for tori (DSC 0.76 except for tori) but showed the largest errors in the recovery of pears and drops dimensions (higher than 10% and 30% of the true length, respectively). Large errors were visible
Hoshyaripour, A.; Vogel, B.; Vogel, H.
2017-12-01
Mineral dust, emitted from arid and semi-arid regions, is the most dominant atmospheric aerosol by mass. Beside detrimental effect on air quality, airborne dust also influences the atmospheric radiation by absorbing and scattering solar and terrestrial radiation. As a result, while the long-term radiative impacts of dust are important for climate, the short-term effects are significant for the photovoltaic energy production. Therefore, it is a vital requirement to accurately forecast the effects of dust on energy budget of the atmosphere and surface. To this end, a major issue is the fact that dust particles are non-spherical. Thus, the optical properties of such particles cannot be calculated precisely using the conventional methods like Mie theory that are often used in climate and numerical weather forecast models. In this study, T-Matrix method is employed, which is able to treat the non-sphericity of particles. Dust particles are assumed to be prolate spheroids with aspect ratio of 1.5 distributed in three lognormal modes. The wavelength-dependent refractive indices of dust are used in T-Matrix algorithm to calculate the extinction coefficient, single scattering albedo, asymmetry parameter and backscattering ratio at different wavelengths. These parameters are then implemented in ICON-ART model (ICOsahedral Nonhydrostatic model with Aerosols and Reactive Trace gases) to conduct a global simulation with 80 km horizontal resolution and 90 vertical levels. April 2014 is selected as the simulation period during which North African dust plumes reached central Europe and Germany. Results show that treatment of non-sphericity reduces the dust AOD in the range of 10 to 30%/. The impacts on diffuse and direct radiation at global, regional and local scales show strong dependency on the size distribution of the airborne dust. The implications for modeling and remote sensing the dust impacts on solar energy are also discussed.
Mishchenko, Michael I.; Yurkin, Maxim A.
2017-01-01
Although the model of randomly oriented nonspherical particles has been used in a great variety of applications of far-field electromagnetic scattering, it has never been defined in strict mathematical terms. In this Letter we use the formalism of Euler rigid-body rotations to clarify the concept of statistically random particle orientations and derive its immediate corollaries in the form of most general mathematical properties of the orientation-averaged extinction and scattering matrices. Our results serve to provide a rigorous mathematical foundation for numerous publications in which the notion of randomly oriented particles and its light-scattering implications have been considered intuitively obvious.
Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles
Energy Technology Data Exchange (ETDEWEB)
Choudhuri, Ahsan [Univ. of Texas, El Paso, TX (United States). Dept. of Mechanical Engineering
2013-06-30
One of the largest challenges for 21st century is to fulfill global energy demand while also reducing detrimental impacts of energy generation and use on the environment. Gasification is a promising technology to meet the requirement of reduced emissions without compromising performance. Coal gasification is not an incinerating process; rather than burning coal completely a partial combustion takes place in the presence of steam and limited amounts of oxygen. In this controlled environment, a chemical reaction takes place to produce a mixture of clean synthetic gas. Gas-solid fluidized bed is one such type of gasification technology. During gasification, the mixing behavior of solid (coal) and gas and their flow patterns can be very complicated to understand. Many attempts have taken place in laboratory scale to understand bed hydrodynamics with spherical particles though in actual applications with coal, the particles are non-spherical. This issue drove the documented attempt presented here to investigate fluidized bed behavior using different ranges of non-spherical particles, as well as spherical. For this investigation, various parameters are controlled that included particle size, bed height, bed diameter and particle shape. Particles ranged from 355 µm to 1180 µm, bed diameter varied from 2 cm to 7 cm, two fluidized beds with diameters of 3.4 cm and 12.4 cm, for the spherical and non-spherical shaped particles that were taken into consideration. Pressure drop was measured with increasing superficial gas velocity. The velocity required in order to start to fluidize the particle is called the minimum fluidization velocity, which is one of the most important parameters to design and optimize within a gas-solid fluidized bed. This minimum fluidization velocity was monitored during investigation while observing variables factors and their effect on this velocity. From our investigation, it has been found that minimum fluidization velocity is independent of bed
Preparation of non-spherical particles by shell-shield etching for near-field nanopatterning
International Nuclear Information System (INIS)
Ye, Jian; Liesbet, Lagae
2014-01-01
The shape of polymer particles plays an important role in determining their function. In this paper, we describe a simple and unconventional method called shell-shield etching (SSE) that allows us to prepare freestanding submicrometer- or micrometer-sized polymer particles with various shapes. By precisely varying the time of ultraviolet ozone treatment under the partial shielding effect of the silica shell, we controllably reshape polymer spheres into symmetry-reduced polymer peaches, mushrooms, bowls, and plates. Finite difference time domain simulations indicate that the non-spherical particles obtained from the SSE method might have potential for near-field nanopatterning applications. (papers)
Ebran, J-P; Khan, E; Nikšić, T; Vretenar, D
2012-07-18
Nucleonic matter displays a quantum-liquid structure, but in some cases finite nuclei behave like molecules composed of clusters of protons and neutrons. Clustering is a recurrent feature in light nuclei, from beryllium to nickel. Cluster structures are typically observed as excited states close to the corresponding decay threshold; the origin of this phenomenon lies in the effective nuclear interaction, but the detailed mechanism of clustering in nuclei has not yet been fully understood. Here we use the theoretical framework of energy-density functionals, encompassing both cluster and quantum liquid-drop aspects of nuclei, to show that conditions for cluster formation can in part be traced back to the depth of the confining nuclear potential. For the illustrative example of neon-20, we show that the depth of the potential determines the energy spacings between single-nucleon orbitals in deformed nuclei, the localization of the corresponding wavefunctions and, therefore, the degree of nucleonic density clustering. Relativistic functionals, in particular, are characterized by deep single-nucleon potentials. When compared to non-relativistic functionals that yield similar ground-state properties (binding energy, deformation, radii), they predict the occurrence of much more pronounced cluster structures. More generally, clustering is considered as a transitional phenomenon between crystalline and quantum-liquid phases of fermionic systems.
International Nuclear Information System (INIS)
Cizewski, J.A.; Henry, R.G.; Lee, C.S.
1991-01-01
The tellurium nuclei with two protons outside of the Z = 50 shell closure exhibit a complicated structure with signatures of collective vibrational, two-quasiparticle, possibly moderately deformed intruder configurations. To study further the structure of the tellurium nuclei the authors made extensive measurements of the (α,xnγ) reactions on even Sn targets, populating excitations in even- and odd-mass Te nuclei up to moderate angular momenta. By examining limits on possible intraband transitions, results suggest that a possible rotational band structure is not supported by the data, since intraband transitions are of comparable E2 strength to interband transitions. In the odd-A isotopes they concentrated on identifying the higher angular momentum negative-parity states (which probe the role of the h 11/2 neutron in the core), and the search for non-yrast negative-parity states, which are a sensitive measure of the shape of the collective excitations
International Nuclear Information System (INIS)
Aprahamian, A.
1992-01-01
Quadrupole oscillations around a deformed shape give rise to vibrations in deformed nuclei. Single phonon vibrations of K = 0 (β) and K = 2 (γ) are a systematic feature in deformed nuclei, but the existence of multi-phonon vibrations had remained an open question until the recently reported results in 168 Er. In this nucleus, a two-phonon K = 4(γγ) band was observed at approximately 2.5 times the energy of the single γ vibration. The authors have studied several deformed rare-earth nuclei using the ( 4 He,2n) reaction in order to map out the systematic behavior of these multi-phonon vibrations. Recently, they have identified a similar K = 4 band in 154 Gd
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
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.
Casertano, Stefano
2016-10-01
Einstein's theory of General Relativity is a key component of our understanding of cosmology, underlying the interpretation of cosmic acceleration in terms of Dark Energy. Gravitational lensing is a major element of modern observational cosmology, used both in reconstructing the mass distribution of galaxies and clusters of galaxies, and in predicting the magnification of sources behind massive clusters. An astrometric verification of gravitational lensing was historically the first experimental test of General Relativity, yet there has been to date no verification of the deflection predicted for a non-spherical source. We propose to use the astrometric capabilities of WFC3 in spatial scan mode to observe the apparent shift in position of several stars in three separate fields during their near-occultation by Jupiter. These measurements will provide two fundamental tests of General Relativity: (1) one of the most precise light-deflection tests ever conducted, and the most precise in the visible, verifying the GR prediction with a precision of 0.04%, and (2) the first measurement of the differential deflection due to the flattening of Jupiter's gravitational potential, verifying the GR prediction of deflection by a *non-spherical* mass with a precision of 5%.
ASPECT RATIO DEPENDENCE OF THE FREE-FALL TIME FOR NON-SPHERICAL SYMMETRIES
International Nuclear Information System (INIS)
Pon, Andy; Johnstone, Doug; Toalá, Jesús A.; Vázquez-Semadeni, Enrique; Gómez, Gilberto C.; Heitsch, Fabian
2012-01-01
We investigate the collapse of non-spherical substructures, such as sheets and filaments, which are ubiquitous in molecular clouds. Such non-spherical substructures collapse homologously in their interiors but are influenced by an edge effect that causes their edges to be preferentially accelerated. We analytically compute the homologous collapse timescales of the interiors of uniform-density, self-gravitating filaments and find that the homologous collapse timescale scales linearly with the aspect ratio. The characteristic timescale for an edge-driven collapse mode in a filament, however, is shown to have a square-root dependence on the aspect ratio. For both filaments and circular sheets, we find that selective edge acceleration becomes more important with increasing aspect ratio. In general, we find that lower dimensional objects and objects with larger aspect ratios have longer collapse timescales. We show that estimates for star formation rates, based upon gas densities, can be overestimated by an order of magnitude if the geometry of a cloud is not taken into account.
Mathaes, Roman; Winter, Gerhard; Besheer, Ahmed; Engert, Julia
2015-03-01
Micro- and nanoparticles in drug and vaccine delivery have opened up new possibilities in pharmaceutics. In the past, researchers focused mainly on particle size, surface chemistry and the use of various materials to control particle characteristics and functions. Lately, shape has been acknowledged as an important design parameter having an impact on the interaction with biological systems. In this review, we report on the latest developments in fabrication methods to tailor particle geometry, summarize analytical techniques for non-spherical particles and highlight the most important findings regarding their interaction with biological systems and their potential applications in drug delivery. The impact of shape on particle internalization into different cell types and particle biodistribution has been extensively studied in the past. Current research focuses on shape-dependent uptake mechanisms and applications for tumour therapy and vaccination. Different fabrication methods can be used to produce a variety of different particle types and shapes. Key challenges will be the transfer of new non-spherical particle fabrication methods from lab-scale to industrial large-scale production. Not all techniques may be scalable for the production of high quantities of particles. It will also be challenging to transfer the promising in vitro findings to suitable in vivo models.
International Nuclear Information System (INIS)
Borghese, F.; Denti, P.; Saija, R.
2007-01-01
The scattering of electromagnetic radiation by nonspherical particles has become an increasingly important research topic over the past 20 years. Instead of handling anisotropic particles of arbitrary shape, the authors consider the more amenable problem of aggregates of spherical particles. This is often a very satisfactory approach as the optical response of nonspherical particles depends more on their general symmetry and the quantity of refractive material than on the precise details of their shape. The book addresses a wide spectrum of applications, ranging from scattering properties of water droplets containing pollutants, atmospheric aerosols and ice crystals to the modeling of cosmic dust grains as aggregates. In this extended second edition the authors have encompassed all the new topics arising from their recent studies of cosmic dust grains. Thus many chapters were deeply revised and new chapters were added. The new material spans the description of the state of polarization of electromagnetic waves of general form, the conservation theorems of combined systems of fields and particles, the appropriate multipole expansion for waves of general wave vector and of general state of polarization, a number of new applications, the effects of radiation pressure and radiation torque on cosmic dust grains, a study of the morphology of cosmic dust grains and of the distribution and polarization of the electromagnetic field in the interior of aggregated dust grains. (orig.)
Investigation of flow regime in debris bed formation behavior with nonspherical particles
Directory of Open Access Journals (Sweden)
Songbai Cheng
2018-02-01
Full Text Available It is important to clarify the characteristics of flow regimes underlying the debris bed formation behavior that might be encountered in core disruptive accidents of sodium-cooled fast reactors. Although in our previous publications, by applying dimensional analysis technique, an empirical model, with its reasonability confirmed over a variety of parametric conditions, has been successfully developed to predict the regime transition and final bed geometry formed, so far this model is restricted to predictions of debris mixtures composed of spherical particles. Focusing on this aspect, in this study a new series of experiments using nonspherical particles have been conducted. Based on the knowledge and data obtained, an extension scheme is suggested with the purpose of extending the base model to cover the particle-shape influence. Through detailed analyses and given our current range of experimental conditions, it is found that, by coupling the base model with this scheme, respectable agreement between experiments and model predictions for the regime transition can be achieved for both spherical and nonspherical particles. Knowledge and evidence from our work might be utilized for the future improvement of design of an in-vessel core catcher as well as the development and verification of sodium-cooled fast reactor severe accident analysis codes in China.
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)
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)
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
Khoa, Dao Tien; Egelhof, Peter; Gales, Sydney; Giai, Nguyen Van; Motobayashi, Tohru
2008-04-01
Studies at the RIKEN RI beam factory / T. Motobayashi -- Dilute nuclear states / M. Freer -- Studies of exotic systems using transfer reactions at GANIL / D. Beaumel et al. -- First results from the Magnex large-acceptance spectrometer / A. Cunsolo et al. -- The ICHOR project and spin-isospin physics with unstable beams / H. Sakai -- Structure and low-lying states of the [symbol]He exotic nucleus via direct reactions on proton / V. Lapoux et al. -- Shell gap below [symbol]Sn based on the excited states in [symbol]Cd and [symbol]In / M. Górska -- Heavy neutron-rich nuclei produced in the fragmentation of a [symbol]Pb beam / Zs. Podolyák et al. -- Breakup and incomplete fusion in reactions of weakly-bound nuclei / D.J. Hinde et al. -- Excited states of [symbol]B and [symbol]He and their cluster aspect / Y. Kanada-En'yo et al. -- Nuclear reactions with weakly-bound systems: the treatment of the continuum / C. H. Dasso, A. Vitturi -- Dynamic evolution of three-body decaying resonances / A. S. Jensen et al. -- Prerainbow oscillations in [symbol]He scattering from the Hoyle state of [symbol]C and alpha particle condensation / S. Ohkubo, Y. Hirabayashi -- Angular dispersion behavior in heavy ion elastic scattering / Q. Wang et al. -- Microscopic optical potential in relativistic approach / Z.Yu. Ma et al. -- Exotic nuclei studied in direct reactions at low momentum transfer - recent results and future perspectives at fair / P. Egelhof -- Isotopic temperatures and symmetry energy in spectator fragmentation / M. De Napoli et al. -- Multi-channel algebraic scattering theory and the structure of exotic compound nuclei / K. Amos et al. -- Results for the first feasibility study for the EXL project at the experimental storage ring at GSI / N. Kalantar-Nayestanaki et al. -- Coulomb excitation of ISOLDE neutron-rich beams along the Z = 28 chain / P. Van Duppen -- The gamma decay of the pygmy resonance far from stability and the GDR at finite temperature / G. Benzoni et al
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)
Beyond mean-field calculations for odd-mass nuclei.
Bally, B; Avez, B; Bender, M; Heenen, P-H
2014-10-17
Beyond mean-field methods are very successful tools for the description of large-amplitude collective motion for even-even atomic nuclei. The state-of-the-art framework of these methods consists in a generator coordinate method based on angular-momentum and particle-number projected triaxially deformed Hartree-Fock-Bogoliubov (HFB) states. The extension of this scheme to odd-mass nuclei is a long-standing challenge. We present for the first time such an extension, where the generator coordinate space is built from self-consistently blocked one-quasiparticle HFB states. One of the key points for this success is that the same Skyrme interaction is used for the mean-field and the pairing channels, thus avoiding problems related to the violation of the Pauli principle. An application to ^{25}Mg illustrates the power of our method, as agreement with experiment is obtained for the spectrum, electromagnetic moments, and transition strengths, for both positive and negative parity states and without the necessity for effective charges or effective moments. Although the effective interaction still requires improvement, our study opens the way to systematically describe odd-A nuclei throughout the nuclear chart.
Yuan, Ye; Jin, Weiwei; Liu, Lufeng; Li, Shuixiang
2017-10-01
The critical behaviors of a granular system at the jamming transition have been extensively studied from both mechanical and thermodynamic perspectives. In this work, we numerically investigate the jamming behaviors of a variety of frictionless non-spherical particles, including spherocylinder, ellipsoid, spherotetrahedron and spherocube. In particular, for a given particle shape, a series of random configurations at different fixed densities are generated and relaxed to minimize interparticle overlaps using the relaxation algorithm. We find that as the jamming point (i.e., point J) is approached, the number of iteration steps (defined as the "time-scale" for our systems) required to completely relax the interparticle overlaps exhibits a clear power-law divergence. The dependence of the detailed mathematical form of the power-law divergence on particle shapes is systematically investigated and elucidated, which suggests that the shape effects can be generally categorized as elongation and roundness. Importantly, we show the jamming transition density can be accurately determined from the analysis of time-scale divergence for different non-spherical shapes, and the obtained values agree very well with corresponding ones reported in literature. Moreover, we study the plastic behaviors of over-jammed packings of different particles under a compression-expansion procedure and find that the jamming of ellipsoid is much more robust than other non-spherical particles. This work offers an alternative approximate procedure besides conventional packing algorithms for studying athermal jamming transition in granular system of frictionless non-spherical particles.
Penionzhkevich, Yu. E.
2016-06-01
This work is an attempt to present some problems on the evolution of the Universe: the nucleosynthesis and cosmochronology from the standpoint of physics of particles and nuclei, in particular with the use of the latest results, obtained by means of radioactive nuclear beams. The comparison is made between the processes taking place in the Universe and the mechanisms of formation and decay of nuclei, as well as of their interaction at different energies. Examples are given to show the capabilities of nuclearphysics methods for studying cosmic objects and properties of the Universe. The results of investigations in nuclear reactions, induced by radioactive nuclear beams, make it possible to analyze the nucleosynthesis scenario in the region of light elements in a new manner.
International Nuclear Information System (INIS)
Dumbrajs, O.
1981-01-01
The concept of the pion-nucleus coupling constants is discussed. Methods of their determination are reviewed. These include: forward dispersion relations, extrapolation of differential cross sections to the poles in the angular variable, analysis of data on electromagnetic form factors with the use of the PCAC and CVC hypotheses, pion photoproduction at threshold and low-energy theorems. Our present knowledge of the pion coupling to the He, Li, Be, C, N and O nuclei is summarized. (author)
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
Non-spherical micelles in an oil-in-water cubic phase
DEFF Research Database (Denmark)
Leaver, M.; Rajagopalan, V.; Ulf, O.
2000-01-01
The cubic phase formed between the microemulsion and hexagonal phases of the ternary pentaethylene glycol dodecyl ether (C12E5)-decane-water system and that doped with small amounts of sodium dodecylsulfate (SDS) have been investigated. The presence of discrete oil-swollen micelles in the cubic...... phase, both with and without SDS, was established by NMR self-diffusion. In addition H-2 NMR relaxation experiments have demonstrated that the micelles in the cubic phase are non-spherical, having grown and changed shape upon formation of the cubic phase from the micellar solution. Small angle...... associated with the micellar cubic phase, Pm3n and Fd3m. The micellar volumes calculated for these space groups are similar and are consistent with a change in micellar geometry from spherical to prolate....
Statistical multifragmentation of non-spherical expanding sources in central heavy-ion collisions
Energy Technology Data Exchange (ETDEWEB)
Le Fevre, A. E-mail: a.lefevre@gsi.de; Ploszajczak, M.; Toneev, V.D.; Auger, G.; Begemann-Blaich, M.L.; Bellaize, N.; Bittiger, R.; Bocage, F.; Borderie, B.; Bougault, R.; Bouriquet, B.; Charvet, J.L.; Chbihi, A.; Dayras, R.; Durand, D.; Frankland, J.D.; Galichet, E.; Gourio, D.; Guinet, D.; Hudan, S.; Hurst, B.; Lautesse, P.; Lavaud, F.; Legrain, R.; Lopez, O.; Lukasik, J.; Lynen, U.; Mueller, W.F.J.; Nalpas, L.; Orth, H.; Plagnol, E.; Rosato, E.; Saija, A.; Schwarz, C.; Sfienti, C.; Tamain, B.; Trautmann, W.; Trzcinski, A.; Turzo, K.; Vient, E.; Vigilante, M.; Volant, C.; Zwieglinski, B.; Botvina, A.S
2004-04-19
We study the anisotropy effects measured with INDRA at GSI in central collisions of {sup 129}Xe+{sup nat}Sn at 50 A MeV and {sup 197}Au+{sup 197}Au at 60, 80, 100 A MeV incident energy. The microcanonical multifragmentation model with non-spherical sources is used to simulate an incomplete shape relaxation of the multifragmenting system. This model is employed to interpret observed anisotropic distributions in the fragment size and mean kinetic energy. The data can be well reproduced if an expanding prolate source aligned along the beam direction is assumed. An either non-Hubblean or non-isotropic radial expansion is required to describe the fragment kinetic energies and their anisotropy. The qualitative similarity of the results for the studied reactions suggests that the concept of a longitudinally elongated freeze-out configuration is generally applicable for central collisions of heavy systems. The deformation decreases slightly with increasing beam energy.
Validity of modifying Mie theory to describe scattering by nonspherical particles
Acquista, C.
1978-01-01
A calculation procedure has been developed (Chylek et al., 1976) for determining the scattering properties of irregularly shaped, randomly oriented particles. The procedure uses a modified form of the Mie theory for spheres with equivalent cross-sectional areas. The validity of the procedure is examined with reference to the work of Welch and Cox (1978). Particular consideration is given to: (1) the assumption that surface waves constitute the only major difference between scattering by spherical and nonspherical particles, (2) the identification of certain properties of the Mie coefficients with surface waves, and (3) the technique of removing surface waves from the Mie theory. It is concluded that the idea of determining the scattering properties of random orientations of irregular particles by eliminating surface waves from the Mie expansion is valid. It is also found that the technique for removing the resonances leads to the introduction of substantial fictitious absorption.
Optical Modeling of Sea Salt Aerosols: The Effects of Nonsphericity and Inhomogeneity
Bi, Lei; Lin, Wushao; Wang, Zheng; Tang, Xiaoyun; Zhang, Xiaoyu; Yi, Bingqi
2018-01-01
The nonsphericity and inhomogeneity of marine aerosols (sea salts) have not been addressed in pertinent radiative transfer calculations and remote sensing studies. This study investigates the optical properties of nonspherical and inhomogeneous sea salts using invariant imbedding T-matrix simulations. Dry sea salt aerosols are modeled based on superellipsoidal geometries with a prescribed aspect ratio and roundness parameter. Wet sea salt particles are modeled as coated superellipsoids, as spherical particles with a superellipsoidal core, and as homogeneous spheres depending on the level of relative humidity. Aspect ratio and roundness parameters are found to be critical to interpreting the linear depolarization ratios (LDRs) of NaCl crystals from laboratory measurements. The optimal morphology parameters of NaCl necessary to reproduce the measurements are found to be consistent with data gleaned from an electron micrograph. The LDRs of wet sea salts are computed based on inhomogeneous models and compared with the measured data from ground-based LiDAR. The dependence of the LDR on relative humidity is explicitly considered. The increase in the LDR with relative humidity at the initial phase of deliquescence is attributed to both the size increase and the inhomogeneity effect. For large humidity values, the LDR substantially decreases because the overall particle shape becomes more spherical and the inhomogeneity effect in a particle on the LDR is suppressed for submicron sea salts. However, the effect of inhomogeneity on optical properties is pronounced for coarse-mode sea salts. These findings have important implications for atmospheric radiative transfer and remote sensing involving sea salt aerosols.
Meng, Q E; Liu, F; Fisher, J; Jin, Z M
2011-01-01
Effective lubrication performance of metal-on-metal hip implants only requires optimum conformity within the main loaded area, while it is advantageous to increase the clearance in the equatorial region. Such a varying clearance can be achieved by using non-spherical bearing surfaces for either acetabular or femoral components. An elastohydrodynamic lubrication model of a novel metal-on-metal hip prosthesis using a non-spherical femoral bearing surface against a spherical cup was solved under loading and motion conditions specified by ISO standard. A full numerical methodology of considering the geometric variation in the rotating non-spherical head in elastohydrodynamic lubrication solution was presented, which is applicable to all non-spherical head designs. The lubrication performance of a hip prosthesis using a specific non-spherical femoral head, Alpharabola, was analysed and compared with those of spherical bearing surfaces and a non-spherical Alpharabola cup investigated in previous studies. The sensitivity of the lubrication performance to the anteversion angle of the Alpharabola head was also investigated. Results showed that the non-spherical head introduced a large squeeze-film action and also led to a large variation in clearance within the loaded area. With the same equatorial clearance, the lubrication performance of the metal-on-metal hip prosthesis using an Alpharabola head was better than that of the conventional spherical bearings but worse than that of the metal-on-metal hip prosthesis using an Alpharabola cup. The reduction in the lubrication performance caused by the initial anteversion angle of the non-spherical head was small, compared with the improvement resulted from the non-spherical geometry.
Toroidal Nuclear Matter Distributions of Superheavy Nuclei from Constrained Skyrme-HFB Calculations
Energy Technology Data Exchange (ETDEWEB)
Kosior, Amelia [Maria Curie-Sklodowska University, Poland; Staszczak, A. [Maria Curie-Sklodowska University, Poland; Wong, Cheuk-Yin [ORNL
2017-01-01
Using the Hartree Fock Bogoliubov (HFB) self-consistent mean-field theory with the SkM* Skyrme energy-density functional, we study nuclear structure properties of even even superheavy nuclei (SHN) of Z = 120 isotopes and N = 184 isotones. The shape of the nucleus along the lowest energy curve as a function of the quadrupole moment Q20 makes a sud- den transition from the oblate spheroids (biconcave discs) to the toroidal shapes, in the region of large oblate quadrupole moments.
Directory of Open Access Journals (Sweden)
Tomio L.
2010-04-01
Full Text Available Universal aspects of few-body systems will be reviewed motivated by recent interest in atomic and nuclear physics. The critical conditions for the existence of excited states in three-body systems with two-identical particles will be explored. In particular, we consider halo nuclei that can be modeled as three-body nuclear systems, with two halo neutrons and a core. In this context, we also discuss the low-energy neutron−19C elastic scattering, near the conditions for the app earance of an Eﬁmov state.
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
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
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
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.)
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
Energy Technology Data Exchange (ETDEWEB)
Diez Muino, R. [Donostia International Physics Center (DIPC), San Sebastian (Spain) and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)]. E-mail: rdm@sc.ehu.es; Rolles, D. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany); Garcia de Abajo, F.J. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Centro Mixto CSIC-UPV/EHU, San Sebastian (Spain); Fadley, C.S. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Department of Physics, University of California at Davis, Davis, CA (United States); Van Hove, M.A. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Department of Physics, University of California at Davis, Davis, CA (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)
2002-08-14
We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s shells of CO and N{sub 2} gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory is thus an efficient method to calculate the scattering states of low-energy electrons in small low-symmetry systems. (author). Letter-to-the-editor.
Energy Technology Data Exchange (ETDEWEB)
Diez Muino, R.; Rolles, D.; Garcia de Abajo, F.J.; Fadley, C.S.; Van Hove, M.A.
2001-09-06
We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s-shells of CO and N2 gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape-resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory thus enhances the sensitivity to spatial electronic distribution and dynamics, paving the way toward their determination from experiment.
Description of highly perturbed bands in rare earth nuclei
International Nuclear Information System (INIS)
Joshi, P.C.; Sood, P.C.
1976-01-01
Recently some highly perturbed positive parity bands have been populated in odd-mass rare earth nuclei. The energy spacings and sometimes even the spin sequences are drastically different from the usual strong coupling rotational model picture. The levels belonging to 'odd and even' I+1/2 are found to make separate groupings. The levels belonging to odd values of I+1/2 are seen to be very much favoured in comparison to the levels for which I+1/2 is even. In some cases only the favoured levels have been identified. These bands have been studied in the frame-work of rotation aligned coupling scheme in which the odd neutron in the unique parity orbital (in this case the isub(13/2) orbital) is strongly decoupled from the body fixed symmetry axis by the Coriolis force so as to make the projection of its angular momentum α on the rotation axis approximately a good quantum number. A description of the energy levels is suggested by assigning the quantum number α-j to the favoured levels and α-j-1 to the unfavoured levels. The intraband transitions of the favoured and unfavoured bands are examined in comparison with those in the adjacent ground state bands in even-even nuclei. (author)
Neutrino interactions with nuclei
International Nuclear Information System (INIS)
Walecka, J.D.
1983-01-01
We examine tests of the Glashow-Weinberg-Salam (GWS) Standard Theory of Electroweak Interactions. The tests are model-independent in the sense that they are relations between experimental quantities that are direct consequences of the GWS theory, but they are independent of the detailed structure of the nucleus. Such relationships were anticipated by Weinberg. Neutrino reactions with nuclei are considered, focusing largely on charged-lepton production, and it is demonstrated that intermediate-energy neutrino reactions have a central and unique role to play in our understanding of semileptonic weak interactions. This point is illustrated by discussing a complete kinematic experiment on the nucleon. A discussion of what neutrino reactions could teach us about nuclear structure is also given
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
International Nuclear Information System (INIS)
2000-01-01
The present collection of letters from JINR, Dubna, contains eight separate records on liquid argon pollution tests of the ATLAS detector materials at IBR-2 reactor in Dubna, irradiation tests of readout chain components of the ATLAS liquid argon calorimeters, study of neutron induced outgassing from tungsten alloy for ATLAS FCAL, yields of nuclear reaction products from a thick beryllium target bombarded by beams of 7 Li, 11 B and 15 N ions as well as on the mass surface and the properties of nuclides close to hypothetic doubly magic lead-164, the Web-site of information-diagnostic system of IBR-2 pulsed neutron source state, discovery of η-mesic nuclei and calculation of the ion angular distributions after the ionization in ion-atom collisions
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)
Properties of α -decay to ground and excited states of heavy nuclei
Wang, Y. Z.; Gu, J. Z.; Dong, J. M.; Peng, B. B.
2010-05-01
Branching ratios and half-lives of α -decay to the ground-state rotational bands as well as the high-lying excited states of even-even nuclei have been calculated in the framework of the generalized liquid drop model (GLDM) and Royer’s formula that we improved very recently. The calculation covers the isotopic chains from Ra to No in the mass regions 222 ≤ A ≤ 252 and 88 ≤ Z ≤ 102 . The agreement between the calculated results and the experimental data indicates the reliability of investigating the properties of the unfavored α -decay with our method, especially the improved Royer’s formula, which is very valuable for the analysis of experimental data. In addition, the dependence of half-lives on excitation energies of daughter nuclei has been investigated. It is shown that the influence on half-lives becomes stronger and stronger with the increase of the excitation energies.
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.
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)
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.
Effects of snow grain non-sphericity on climate simulations: Sensitivity tests with the NorESM model
Räisänen, Petri; Makkonen, Risto; Kirkevåg, Alf
2017-04-01
Snow grains are non-spherical and generally irregular in shape. Still, in radiative transfer calculations, they are often treated as spheres. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR) model and in the Los Alamos sea ice model, version 4 (CICE4), both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM). In this work, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH) is compared with another (NONSPH) in which the snow shortwave single-scattering properties are based on a combination of non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (≈ 0.78 in the visible region) than in the spherical case (≈ 0.89). Therefore, for a given snow grain size, the use of non-spherical snow grains yields a higher snow broadband albedo, typically by ≈0.03. Consequently, considering the spherical case as the baseline, the use of non-spherical snow grains results in a negative radiative forcing (RF), with a global-mean top-of-the-model value of ≈ -0.22 W m-2. Although this global-mean RF is modest, it has a rather substantial impact on the climate simulated by NoRESM. In particular, the global annual-mean 2-m air temperature in NONSPH is 1.17 K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further found that the difference between NONSPH and SPH could be largely "tuned away" by adjusting the snow grain size in the NONSPH experiment by ≈ 70%. The impact of snow grain shape on the radiative effect (RE) of absorbing aerosols in snow (black carbon and mineral dust) is also discussed. For an
Energy Technology Data Exchange (ETDEWEB)
Inakura, T. [University of Tsukuba, Institute for Physics, Tsukuba (Japan); Nakatsukasa, T. [RIKEN Nishina Center, Theoretical Nuclear Physics Laboratory, Wako (Japan); Yabana, K. [University of Tsukuba, Institute for Physics, Tsukuba (Japan); University of Tsukuba, Center for Computational Sciences, Tsukuba (Japan)
2009-12-15
We undertake a systematic calculation on electric-dipole responses of even-even nuclei for a wide mass region employing a fully self-consistent Hartree-Fock plus RPA approach. For an easy implementation of the fully self-consistent calculation, the finite-amplitude method which we have proposed recently is employed. We calculated dipole responses in Cartesian mesh representation, which can deal with deformed nuclei but do not include pairing correlation. The systematic calculation has reached Nickel isotopes. The calculated results show reasonable agreement for heavy nuclei while the average excitation energies are underestimated for light nuclei. We show a systematic comparison of the splitting of the peak energy with the ground-state deformation. (orig.)
The cochlear nuclei of snakes.
Miller, M R
1980-08-15
The cochlear nuclei of three burrowing snakes (Xenopeltis unicolor, Cylindrophis rufus, and Eryx johni) and three non-burrowing snakes (Epicrates cenchris, Natrix sipedon, and Pituophis catenifer) were studied. The posterior branch of the statoacoustic nerve and its posterior ganglion were destroyed and the degenerated nerve fibers and terminals traced to primary cochlear nuclei in 13 specimens of Pituophis catenifer. All these snake species possess three primary and one secondary cochlear nuclei. The primary cochlear nuclei consist of a small nucleus angularis located at the cerebello-medullary junction and a fairly large nucleus magnocellularis forming a dorsal cap over the cephalic end of the alar eminence. Nucleus magnocellularis may be subdivided into a medially placed group of rounder cells, nucleus magnocellularis medialis, and a laterally placed group of more ovate and paler-staining cells, nucleus magnocellularis lateralis. A small but well-defined secondary nucleus which showed no degenerated nerve terminals after nerve root section, nucleus laminaris, underlies the cephalic part of both nucleus magnocellularis medialis and nucleus magnocellularis lateralis. Larger and better-developed cochlear nuclei were found in burrowing species than in non-burrowing species of snakes. Of the three burrowing species studied, Xenopeltis showed the greatest development of cochlear nuclei; Eryx cochlear nuclei were not quite as large but were better differentiated than in Xenopeltis; and Cylindrophis cochlear nuclei were fairly large but not as well developed nor as well differentiated as in either Xenopeltis or Eryx. The cochlear nuclei of the three non-burrowing snakes, Epicrates, Natrix, and Pituophis, were not as large nor as well developed as those of the burrowing snakes. There is some, but not complete, correlation between cochlear development and papilla basilaris length and number of hair cells. Thus, Xenopeltis and Eryx, with well-developed cochlear nuclei
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.
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')
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...
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)
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
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
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.
Examination of Effective Dielectric Constants Derived from Non-Spherical Melting Hydrometeor
Liao, L.; Meneghini, R.
2009-04-01
The bright band, a layer of enhanced radar echo associated with melting hydrometeors, is often observed in stratiform rain. Understanding the microphysical properties of melting hydrometeors and their scattering and propagation effects is of great importance in accurately estimating parameters of the precipitation from spaceborne radar and radiometers. However, one of the impediments in the study of the radar signature of the melting layer is the determination of effective dielectric constants of melting hydrometeors. Although a number of mixing formulas are available to compute the effective dielectric constants, their results vary to a great extent when water is a component of the mixture, such as in the case of melting snow. It is also physically unclear as to how to select among these various formulas. Furthermore, the question remains as to whether these mixing formulas can be applied to computations of radar polarimetric parameters from non-spherical melting particles. Recently, several approaches using numerical methods have been developed to derive the effective dielectric constants of melting hydrometeors, i.e., mixtures consisting of air, ice and water, based on more realistic melting models of particles, in which the composition of the melting hydrometeor is divided into a number of identical cells. Each of these cells is then assigned in a probabilistic way to be water, ice or air according to the distribution of fractional water contents for a particular particle. While the derived effective dielectric constants have been extensively tested at various wavelengths over a range of particle sizes, these numerical experiments have been restricted to the co-polarized scattering parameters from spherical particles. As polarimetric radar has been increasingly used in the study of microphysical properties of hydrometeors, an extension of the theory to polarimetric variables should provide additional information on melting processes. To account for polarimetric
Cavitation inception from bubble nuclei
DEFF Research Database (Denmark)
Mørch, Knud Aage
2015-01-01
The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years....... 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...... and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes....
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
Description of odd-mass nuclei by multi-reference energy density functional methods
International Nuclear Information System (INIS)
Bally, B.
2014-01-01
In this work, we are interested in the treatment of odd-mass atomic nuclei in energy density functional (EDF) models. More precisely, the goal of this thesis is to develop and to apply to odd-mass nuclei, the theoretical extensions of the EDF method that are: first, the projection technique, and secondly the configuration mixing by the generator coordinate method (GCM). These two extensions are part of the so-called multi-reference energy density functional (MR-EDF) formalism and allow one to take into account, within an EDF context, the 'beyond-mean-field' correlations between the nucleons forming the nucleus. Until now, the MR-EDF formalism has been applied, in its fully-fledged version, only to the calculation of even-even nuclei. In this thesis, we want to demonstrate the applicability of such a model also for the description of odd-mass nuclei. In the first part of this thesis, we describe the theoretical formalism of the EDF models, giving particular attention to the treatment of symmetries within our approach. In the second part of the manuscript, we apply our model to the nucleus 25 Mg and investigate different aspects of the method (e.g. numerical accuracy, convergence of the configuration mixing, comparison to known experimental data). The results obtained in this work are encouraging and demonstrate the potential of our approach for theoretical nuclear structure calculations. (author)
Spontaneous fission of superheavy nuclei in a macroscopic-microscopic model
International Nuclear Information System (INIS)
Lojewski, Z.
2012-01-01
A systematic study of spontaneous fission half-lives of superheavy nuclei in the framework of the macroscopic-microscopic method was performed. The macroscopic-microscopic calculations of the half-lives consist in determining the collective potential energy V which splits into microscopic and smooth average macroscopic parts as well as into a nucleus mass tensor of the nucleus undergoing the fission process. The microscopic part of the energy is calculated using the single-particle Woods-Saxon potential with a universal set of parameters. Two models of the residual pairing interaction were studied. In the first approach we used monopole pairing (with constant matrix elements G). In the second approximation the pairing matrix elements were calculated with ?-force and are state dependent. As the macroscopic part of collective energy we examined four different macroscopic models of nuclear energy: Myers - Swiatecki liquid drop, Droplet expansion, Yukawa-plus-Exponential and the Lublin-Strasbourg Drop model. The analysis covers a wide range of even-even superheavy nuclei from Z = 100 to Z = 126. The calculations of spontaneous fission half-lives were performed by means of a WKB approximation, in the multi-dimensional dynamical-programming method within parameters describe the shape of nuclei. The studies offer an opportunity of a comprehensive approach to a very interesting group of exotic heavier nuclei, which are currently investigated by experimenters
Nuclei Isolation from Nematode Ascaris
Kang, Yuanyuan; Wang, Jianbin; Davis, Richard E.
2017-01-01
Preparing nuclei is necessary in a variety of experimental paradigms to study nuclear processes. In this protocol, we describe a method for rapid preparation of large number of relatively pure nuclei from Ascaris embryos or tissues that are ready to be used for further experiments such as chromatin isolation and ChIP-seq, nuclear RNA analyses, or preparation of nuclear extracts (Kang et al., 2016; Wang et al., 2016). PMID:29082294
International Nuclear Information System (INIS)
Klüser, Lars; Di Biagio, Claudia; Kleiber, Paul D.; Formenti, Paola; Grassian, Vicki H.
2016-01-01
Optical properties (extinction efficiency, single scattering albedo, asymmetry parameter and scattering phase function) of five different desert dust minerals have been calculated with an asymptotic approximation approach (AAA) for non-spherical particles. The AAA method combines Rayleigh-limit approximations with an asymptotic geometric optics solution in a simple and straightforward formulation. The simulated extinction spectra have been compared with classical Lorenz–Mie calculations as well as with laboratory measurements of dust extinction. This comparison has been done for single minerals and with bulk dust samples collected from desert environments. It is shown that the non-spherical asymptotic approximation improves the spectral extinction pattern, including position of the extinction peaks, compared to the Lorenz–Mie calculations for spherical particles. Squared correlation coefficients from the asymptotic approach range from 0.84 to 0.96 for the mineral components whereas the corresponding numbers for Lorenz–Mie simulations range from 0.54 to 0.85. Moreover the blue shift typically found in Lorenz–Mie results is not present in the AAA simulations. The comparison of spectra simulated with the AAA for different shape assumptions suggests that the differences mainly stem from the assumption of the particle shape and not from the formulation of the method itself. It has been shown that the choice of particle shape strongly impacts the quality of the simulations. Additionally, the comparison of simulated extinction spectra with bulk dust measurements indicates that within airborne dust the composition may be inhomogeneous over the range of dust particle sizes, making the calculation of reliable radiative properties of desert dust even more complex. - Highlights: • A fast and simple method for estimating optical properties of dust. • Can be used with non-spherical particles of arbitrary size distributions. • Comparison with Mie simulations and
Possible "umbrella"-like antimagnetic rotation mode in odd-A Pd,103101 and even-even Pd,104102
Jia, H.; Qi, B.; Liu, C.; Hu, Q.; Wang, S. Y.
2018-02-01
The tilted-axis cranking model based on covariant density functional theory is used to study the candidate antimagnetic rotation (AMR) bands in 101,102,103,104Pd. The experimental energy spectra and B (E 2) values are reproduced well in the self-consistent and microscopic calculations. By investigating microscopically the composition and orientation of angular momentum, an "umbrella"-like antimagnetic rotation (UAMR) mode resulting from the coupling of four g9 /2 proton holes to neutron particles is clearly illustrated for the first time.
Skotheim, J. M.; Secomb, T. W.
2007-02-01
We consider the motion of red blood cells and other nonspherical microcapsules dilutely suspended in a simple shear flow. Our analysis indicates that depending on the viscosity, membrane elasticity, geometry, and shear rate, the particle exhibits either tumbling, tank-treading of the membrane about the viscous interior with periodic oscillations of the orientation angle, or intermittent behavior in which the two modes occur alternately. For red blood cells, we compute the complete phase diagram and identify a novel tank-treading-to-tumbling transition as the shear rate decreases. Observations of such motions coupled with our theoretical framework may provide a sensitive means of assessing capsule properties.
Kuo, K.; Clune, T.; Pearson, C.; Olson, W. S.; Skofronick-Jackson, G.; Gravner, J.; Griffeath, D.
2010-12-01
This study improves upon an earlier, preliminary study using only three size bins based on maximum diameter in which it is found that the single-scattering properties of ensembles of non-spherical precipitation particles can be better characterized by considering the non-convexity of these particles. The difficulty of retrievals involving non-spherical particles stems not only from the fact that these particles are not spherical but also the fact that the shape composition of an ensemble of particles is usually unknown and the possibility of its mixture is infinite. Being able to adequately characterize the single-scattering properties of ensembles involving these non-spherical particles with as few parameters as possible is at the heart of solving this thorny remote sensing problem. Inspired by how well three parameters, i.e. water content, effective radius, and effective variance (or their equivalent), characterize the single-scattering properties of an ensemble of spherical particles of varying sizes, we set out to find additional parameters that generalize these three for ensembles of non-spherical particles. We find that a non-convexity measure appears to be one of these additional parameters. Non-convexity is expressed as a ratio of two effective radii derived from the moments of a given particle size distribution (PSD), each of which is in essence a ratio of ensemble particle volume to area. The effective radius in the numerator (denoted as rA) of the non-convexity ratio is based on the projection area of the particle ensemble whereas the one in the denominator (denoted as rS) is based on the surface area. In the preliminary study with PSDs having only three size bins, it is found that variations in the single-scattering properties, such as the scattering and extinction coefficients, the asymmetry factor, and even the scattering phase function, of a particle ensemble with a specified water content are very limited (practically non-existent), if 1) the habit
Xuhao Wang; Dawei Zhang; Chen Zhao
2017-01-01
The 7R 6-DOF robots with hollow nonspherical wrist have been proven more suitable for spray painting applications. However, the inverse kinematics of this kind of robot is still imperfect due to the coupling between position and orientation of the end-effector (EE). In this paper, a new and efficient algorithm for the inverse kinematics of a 7R 6-DOF robot is proposed. The proposed inverse kinematics algorithm is a two-step method. The geometry of the 7R 6-DOF robot is analyzed. A comparison ...
DEFF Research Database (Denmark)
Duvnjak, Stevo; Ravn, Pernille; Green, Anders
2016-01-01
fibroids treated with uterine fibroid embolization (UFE) with spherical (s-PVA) and nonspherical (ns-PVA) polyvinyl alcohol microparticles during the period January 2001 to January 2011. Clinical success and secondary interventions were examined. Hospital records were reviewed during follow-up, and symptom...... embolized with ns-PVA compared with 134 patients (58 %) treated with s-PVA. Thirty-three patients (28 %) underwent secondary interventions in the ns-PVA group compared with 98 patients (42 %) in s-PVA group (χ2 test, p PVA particles 500–700 µm showed high reintervention rate...
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)
Hu, Shuai; Gao, Taichang; Li, Hao; Yang, Bo; Jiang, Zidong; Liu, Lei; Chen, Ming
2017-10-01
The performance of absorbing boundary condition (ABC) is an important factor influencing the simulation accuracy of MRTD (Multi-Resolution Time-Domain) scattering model for non-spherical aerosol particles. To this end, the Convolution Perfectly Matched Layer (CPML), an excellent ABC in FDTD scheme, is generalized and applied to the MRTD scattering model developed by our team. In this model, the time domain is discretized by exponential differential scheme, and the discretization of space domain is implemented by Galerkin principle. To evaluate the performance of CPML, its simulation results are compared with those of BPML (Berenger's Perfectly Matched Layer) and ADE-PML (Perfectly Matched Layer with Auxiliary Differential Equation) for spherical and non-spherical particles, and their simulation errors are analyzed as well. The simulation results show that, for scattering phase matrices, the performance of CPML is better than that of BPML; the computational accuracy of CPML is comparable to that of ADE-PML on the whole, but at scattering angles where phase matrix elements fluctuate sharply, the performance of CPML is slightly better than that of ADE-PML. After orientation averaging process, the differences among the results of different ABCs are reduced to some extent. It also can be found that ABCs have a much weaker influence on integral scattering parameters (such as extinction and absorption efficiencies) than scattering phase matrices, this phenomenon can be explained by the error averaging process in the numerical volume integration.
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.)
Black holes in binary stellar systems and galactic nuclei
International Nuclear Information System (INIS)
Cherepashchuk, A M
2014-01-01
In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M BH =(4−20)M ⊙ ) in X-ray binary systems and of several hundred supermassive black holes (M BH =(10 6 −10 10 )M ⊙ ) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a ∗ have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a ∗ =0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths λ≲1 mm (the international program, Event Horizon Telescope). (100
Energy Technology Data Exchange (ETDEWEB)
Benmicia, N.; Benrachi, F. [Laboratoire de Physique Mathematique et Subatomique, Majister, Mentouri University, Constantine (Algeria)
2012-06-27
One of the most interesting topics in nuclear structure is the study of nuclei near the limits of particle stability. Much attention is currently being focused on nuclei with few valence nucleons around Z= 28, 50 and 82, in particular the 68Ni, 132Sn and 208Pb neighbors. We are interested of the even-even isobars 72Ni, 72Ge and 72Zn in 68Ni region, 136Sn, 136Xe and 136Te in 132Sn region, 212Pb, 212Rn and 212Po in 208Pb region. The calculation of energies spectra using the effective interactions JUN45M, CW{Delta}5082 and KHP shows a good agreement with the available experimental data for the energie levels and their sequences. We have extended the existed similarity between lead and tin regions to the Nickel region.
Breaking of the SU(4) limit for the Gamow-Teller strength in N{proportional_to}Z nuclei
Energy Technology Data Exchange (ETDEWEB)
Petermann, I. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Gesellschaft fuer Schwerionenforschung Darmstadt, Darmstadt (Germany); Martinez-Pinedo, G. [Gesellschaft fuer Schwerionenforschung Darmstadt, Darmstadt (Germany); Langanke, K. [Gesellschaft fuer Schwerionenforschung Darmstadt, Darmstadt (Germany); Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Caurier, E. [Universite Louis Pasteur, Institut de Recherches Subatomiques, Strasbourg (France)
2007-12-15
We have performed large-scale shell model calculations of the Gamow-Teller strength distributions in N{proportional_to}Z pf-shell nuclei. These calculations were motivated by the experimental attempts to measure the low-lying GT strength for the even-even N=Z+2 or N=Z-2 nuclei {sup 46}Ti, {sup 50}Cr, {sup 54}Fe and {sup 62}Ge, where a sizable low-energy GT strength could be interpreted as reminiscence of SU(4) symmetry; in the limit of exact SU(4) symmetry the GT{sub -} strength would be concentrated in a single transition to the lowest T=0, J=1{sup +} state in the daughter. We confirm that the SU(4) symmetry is strongly broken by the spin-orbit interaction and by increasing neutron excess. (orig.)
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 ...
Spontaneous fission of superheavy nuclei
Indian Academy of Sciences (India)
collaborators [1,2]. The importance of deformed valleys in the potential energy surfaces. (PES) is that they provide the most favoured fission channels for the decay of superheavy nuclei. For the dynamics study, one has to introduce the influence of mass tensor. We use the results from pairing calculations for the occupation ...
Cavitation Nuclei: Experiments and Theory
DEFF Research Database (Denmark)
Mørch, Knud Aage
2009-01-01
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....
Weak pion production from nuclei
Indian Academy of Sciences (India)
Abstract. The charged current pion production induced by neutrinos in 12C, 16O and 56Fe nuclei has been studied. The calculations have been done for the coherent as well as the incoherent processes assuming dominance and takes into account the effect of Pauli blocking, Fermi motion and the renormalization of in ...
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
Spontaneous fission of superheavy nuclei
Indian Academy of Sciences (India)
2015-08-02
Aug 2, 2015 ... ... nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped daughter and emitted fragment nuclei. The macroscopic part is obtained using the Yukawa-plus-exponential potential.
Proton scattering from unstable nuclei
Indian Academy of Sciences (India)
Abstract. Recent improvements in the intensities and optical qualities of radioactive beams have made possible the study of elastic and inelastic proton scattering on unstable nuclei. The design and performances of an innovative silicon strip detector array devoted to such experiments are described. The quality of the data ...
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...
Unintegrated parton distributions in nuclei
de Oliveira, E. G.; Martin, A. D.; Navarra, F. S.; Ryskin, M. G.
2013-09-01
We study how unintegrated parton distributions in nuclei can be calculated from the corresponding integrated partons using the EPS09 parametrization. The role of nuclear effects is presented in terms of the ratio R A = uPDF A / A·PDF N for both large and small x domains.
Weak pion production from nuclei
Indian Academy of Sciences (India)
The pion production processes from nucleons and nuclei at intermediate energies are important tools to study the hadronic structure. The dynamic models of the hadronic structure are used to calculate the various nucleon and transition form factors which are tested by using the experimental data on photo, electro and.
Ichinose, G. A.; Ford, S. R.; Myers, S.; Pasyanos, M.; Walter, W. R.
2016-12-01
The 6 January 2016, 12 February 2013 and 25 May 2009 declared nuclear explosions at the Punggye-ri test site in the Democratic People's Republic of Korea (DPRK) were all closely located providing an opportunity to perform differential analysis. We used spectral ratios of surface waves between 50 and 10 sec period between the co-located events to isolate relative explosion amplitude radiation patterns by the cancelation of propagation and site effects. We calculated the spectral ratios using a dense array of 72 NIED F-NET stations across Japan and all available IMS, IC and IU network stations. Analyses of Rayleigh waves indicated non-spherical radiation for the 2016 and 2013 tests relative to 2009. The 2016/2009 and 2013/2009 event pairs had ellipsoidal radiation patterns. The 2016/2009 pair had an ellipse major axis oriented 123 degrees from north and the 2013/2009 pair was oriented 33 degrees from north. This suggests that both 2016 and 2013 explosions have non-spherical radiation and also that the radiation between 2016 and 2013 were rotated by 90 degrees. This radiation pattern was strongest in the 20 and 33 sec period band but was also observed in the 10 and 50 sec band with higher scatter. We did not discern any Love wave radiation patterns but there is high scatter possibly due to a lower long-period signal to noise ratio on the horizontal relative to the vertical components. There are several possible source models that can theoretically cause non-spherical radiation, for example topography, spall damage, or tectonic release. One implication we have identified is that the radiation pattern makes it problematic for the use of surface waves in relative relocations, typically more robust for earthquakes. The amount of departure from purely spherical radiation is consistent with the 20-30% CLVD and 60-70% isotropic components estimated from regional long-period moment tensor solutions for the two explosions. This work performed under the auspices of the US
Symmetry energy and surface properties of neutron-rich exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Gaidarov, M. K.; Antonov, A. N. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Sarriguren, P. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Moya de Guerra, E. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)
2014-07-23
The symmetry energy, the neutron pressure and the asymmetric compressibility of spherical Ni, Sn, and Pb and deformed Kr and Sm neutron-rich even-even nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the deformed self-consistent mean-field Skyrme HF+BCS method. The mass dependence of the nuclear symmetry energy and the neutron skin thickness are also studied together with the role of the neutron-proton asymmetry. The studied correlations reveal a smoother behavior in the case of spherical nuclei than for deformed ones. We also notice that the neutron skin thickness obtained for {sup 208}Pb with SLy4 force is found to be in a good agreement with the recent data. In addition to the interest that this study may have by itself, we give some numerical arguments in proof of the existence of peculiarities of the studied quantities in Ni and Sn isotopic chains that are not present in the Pb chain.
Coulomb Excitation of Neutron-Rich $A\\approx$140 Nuclei
Van duppen, P L E
2002-01-01
Investigating the isospin dependence of the product between the B( E2; 0$_{1}^{+} \\rightarrow 2_{1}^{+}$)-value and the 2$_{1}^{+}$-excitation energy E$_{2^{+}}$ in even-even nuclei around $A\\!\\approx$140 one observes a rather smooth trend close to the valley of stability but clear indication for a reduction from the extrapolated B(E2)-values by one order of magnitude for some very neutron-rich nuclei. While close to the valley of stability the strong neutron-proton interaction results in an equilibration of the neutron and proton deformations with a predominate isoscalar character of the collective 2$^{+}$ excitation, it is conceivable that more loosely bound neutrons cannot polarize a close-to-magic proton core that well any more. This might result in a decoupling of the shape of the outer neutrons from the core and in a strong isovector admixture to the lowest lying 2$^{+}$ level. In this way the 2$^{+}$ -energies could be further lowered in neutron-rich nuclei, while the quadrupole moments of the proton c...
Shape transition with temperature of the pear-shaped nuclei in covariant density functional theory
Zhang, W.; Niu, Y. F.
2017-11-01
The shape evolutions of the pear-shaped nuclei 224Ra and even-even Ba-154144 with temperature are investigated by the finite-temperature relativistic mean field theory with the treatment of pairing correlations by the BCS approach. The free energy surfaces as well as the bulk properties including deformations, pairing gaps, excitation energy, and specific heat for the global minimum are studied. For 224Ra, three discontinuities found in the specific heat curve indicate the pairing transition at temperature 0.4 MeV and two shape transitions at temperatures 0.9 and 1.0 MeV, namely one from quadrupole-octupole deformed to quadrupole deformed, and the other from quadrupole deformed to spherical. Furthermore, the gaps at N =136 and Z =88 are responsible for stabilizing the octupole-deformed global minimum at low temperatures. Similar pairing transition at T ˜0.5 MeV and shape transitions at T =0.5 -2.2 MeV are found for even-even Ba-154144. The transition temperatures are roughly proportional to the corresponding deformations at the ground states.
Go, S.; Kim, J.; KIM, M.; Choi, M.; Lim, H.
2017-12-01
Non-spherical assumption of particle shape has been used to replace the spherical assumption in the Geostationary Environment Monitoring Spectrometer (GEMS) aerosol optical properties retrievals for dust particles. GEMS aerosol retrieval algorithms are based on optimal estimation method to provide aerosol optical depth (AOD), single scattering albedo (SSA) at 443nm, and aerosol loading height (ALH) simultaneously as products. Considering computing time efficiency, the algorithm takes Look-Up Table (LUT) approach using Vector Linearized Discrete Ordinate Radiative Transfer code (VLIDORT), and aerosol optical properties for three aerosol types of absorbing fine aerosol (BC), dust and non-absorbing aerosol (NA) are integrated from AERONET inversion data, and fed into the LUT calculation. In this study, by applying the present algorithm to OMI top-of the atmosphere normalized radiance, retrieved AOD, SSA with both spherical and non-spherical assumptions have been compared to the surface AERONET observations at East Asia sites for 3 years from 2005 to 2007 to evaluate and quantify the effect of non-spherical dust particles on the satellite aerosol retrievals. The root-mean-square error (RMSE) in the satellite retrieved AOD have been slightly reduced as a result of adopting the non-spherical assumption in the GEMS aerosol retrieval algorithm. For SSA, algorithm tested with spheroid models on dust particle shows promising results for the improved SSA. In terms of ALH, the results are qualitatively compared with CALIOP products, and shows consistent variation. This result suggests the importance of taking into account the effects of non-sphericity in the retrieval of dust particles from GEMS measurements.
Directory of Open Access Journals (Sweden)
Shrestha Siddhartha
2017-01-01
Full Text Available Bubble dynamics significantly affect the hydrodynamics of gas-solid fluidized bed since they influence the gas-solid mixing. In this study, simulations using CFD-DEM were carried out to characterize the bubble size and shape for a bubble formed at a single orifice in gas-solid fluidized bed. Impact of parameters such as jet velocity, orifice size and particle shape on bubble equivalent diameter and bubble aspect ratio were analysed and discussed. Bubble equivalent diameter was found to increase with increasing jet velocity, decreasing bed width to orifice width ratio, and particle shape deviating from spherical. The bubble shape illustrated by aspect ratio, was found to elongate more as it rise through the bed and then commence to expand horizontally after it was detached from the orifice. Aspect ratio was found to be closer to a circle for the bubble at higher jet velocity, lower orifice width to bed ratio and for non-spherical particles.
Shrestha, Siddhartha; Zhou, Zongyan
2017-06-01
Bubble dynamics significantly affect the hydrodynamics of gas-solid fluidized bed since they influence the gas-solid mixing. In this study, simulations using CFD-DEM were carried out to characterize the bubble size and shape for a bubble formed at a single orifice in gas-solid fluidized bed. Impact of parameters such as jet velocity, orifice size and particle shape on bubble equivalent diameter and bubble aspect ratio were analysed and discussed. Bubble equivalent diameter was found to increase with increasing jet velocity, decreasing bed width to orifice width ratio, and particle shape deviating from spherical. The bubble shape illustrated by aspect ratio, was found to elongate more as it rise through the bed and then commence to expand horizontally after it was detached from the orifice. Aspect ratio was found to be closer to a circle for the bubble at higher jet velocity, lower orifice width to bed ratio and for non-spherical particles.
Carvalho, J. P. S.
2017-10-01
In this work, we present an approach taking into account the single-averaged equations and unaveraged equations to investigate the dynamics of artificial satellites on the effect due to the non-spherical shape of the planet Mercury. An analysis considering the long-period terms and another taking into account the short-period terms is presented. The numerical integrations of the equations developed are performed using the Maple software. We consider the numerical values of the most updated spherical harmonic coefficients in the literature. Emphasis is given to analyze the effect of the C22 term in the dynamics of the spacecraft. We show that the two techniques are in agreement (average or not average). We found orbits that librates around an equilibrium point with small variation of the orbital elements, in particular the eccentricity and argument of the pericenter. We also note that the C22 term contributes to reduce the growth of the orbital eccentricity.
Kudryavtsev, S. M.
The high-precision analytical theory of a nonspherical planet satellite has been developed. All perturbations proportional to the product J (sub lm) x J(sub pq) x J(sub rs) x J(sub kn) (where J(sub ij) is an arbitrary harmonic of planet potential expansion) are calculated. The influence of the high-order perturbations on the motion of a satellite over long-term intervals has been investigated. The results of a comparison of the numeric and analytical integrations of the satellite motion equations over a two year interval are as follows: for the ETALON-1 satellite the rms error is 5.6 cm; for the Phobos moon the rms error is 2.5 cm. The theory is intended to be used for processing precise laser measurements of the Earth passive geodynamic satellites in long-term intervals.
Analysis of non-spherical grid geometry for distortion-free LEED apparatus with micro channel plate
International Nuclear Information System (INIS)
Okano, Tatsuo; Ohsaki, Akihiko; Sakurai, Makoto; Honda, Tohru; Tuzi, Yutaka
1985-01-01
A design of non-spherical grid structure for the distortion-free LEED apparalus with a micro channel plate (MCP) is described. The grid structure is assumed as an interface of two electrostatic potentials. The potential interface refracts the diffracted electrons and the LEED patterns can be projected on the MCP just like those observed on a spherical fluorescent screen. The shape of the potential interface is described by a differential equation and numerically calculated for several conditions. The most appropriate geometry is determined by the easiness of the mechanical construction. The effect of energy distribution of diffracted electrons is numerically estimated and the deviation is proved to be negligibly small for most applications. (author)
Pollack, J. B.; Cuzzi, J. N.
1980-01-01
An approximate method is proposed for evaluating the interaction of randomly oriented, nonspherical particles with the total intensity component of electromagnetic radiation. When the particle size parameter, x, the ratio of particle circumference to wavelength, is less than some upper bound x(o) (about 5), Mie theory is used. For x greater than x(o), the interaction is divided into three components: diffraction, external reflection, and transmission. Physical optics theory is used to obtain the first of these components; geometrical optics theory is applied to the second; and a simple parameterization is employed for the third. The predictions of this theory are found to be in very good agreement with laboratory measurements for a wide variety of particle shapes, sizes, and refractive indexes. Limitations of the theory are also noted.
Extended M1 sum rule for excited symmetric and mixed-symmetry states in nuclei
International Nuclear Information System (INIS)
Smirnova, N.A.; Pietralla, N.; Leviatan, A.; Ginocchio, J.N.; Fransen, C.
2002-01-01
A generalized M1 sum rule for orbital magnetic dipole strength from excited symmetric states to mixed-symmetry states is considered within the proton-neutron interacting boson model of even-even nuclei. Analytic expressions for the dominant terms in the B(M1) transition rates from the 2 1,2 + states are derived in the U(5) and SO(6) dynamic symmetry limits of the model, and the applicability of a sum rule approach is examined at and between these limits. Lastly, the sum rule is applied to the new data on mixed-symmetry states of 94 Mo and a quadrupole d-boson ratio n d (0 1 + )/n d (2 2 + )≅0.6 is obtained in a largely parameter-independent way
Isospin Mixing in Nuclei Around N ∼ Z and the Superallowed β-Decay
International Nuclear Information System (INIS)
Satula, W.; Dobaczewski, J.; Nazarewicz, W.; Rafalski, M.
2011-01-01
Theoretical approaches that use one-body densities as dynamical variables, such as Hartree-Fock or the density functional theory (DFT), break isospin symmetry both explicitly, by virtue of charge-dependent interactions, and spontaneously. To restore the spontaneously broken isospin symmetry, we implemented the isospin-projection scheme on top of the Skyrme-DFT approach. This development allows for consistent treatment of isospin mixing in both ground and exited nuclear states. In this study, we apply this method to evaluate the isospin impurities in ground states of even-even and odd-odd N ∼ Z nuclei. By including simultaneous isospin and angular-momentum projection, we compute the isospin-breaking corrections to the 0 + → 0 + superallowed β-decay. (authors)
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...
Energy Technology Data Exchange (ETDEWEB)
Pittel, S. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, 19716 Delaware (United States); Dussel, G. G. [Departamento de Fisica J.J. Giambiagi, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Dukelsky, J.; Sarriguren, P. [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)
2008-12-15
We describe recent efforts to study Cooper pairs in atomic nuclei. We consider a self-consistent Hartree Fock mean field for the even Sm isotopes and compare results based on three treatments of pairing correlations: a BCS treatment, a number-projected BCS treatment and an exact treatment using the Richardson Ansatz. Significant differences are seen in the pairing correlation energies. Furthermore, because it does not average over the properties of the fermion pairs, the Richardson solution permits a more meaningful definition of the Cooper wave function and of the fraction of pairs that are collective. Our results confirm that only a few pairs near the Fermi surface in realistic atomic nuclei are collective. (Author)
Relativistic description of deformed nuclei
International Nuclear Information System (INIS)
Price, C.E.
1988-01-01
The author has shown that relativistic Hartree calculations using parameters that have been fit to the properties of nuclear matter can provide a good description of both spherical and axially deformed nuclei. The quantitative agreement with experiment is equivalent to that which was obtained in non-relativistic calculations using Skyrme interactions. The equilibrium deformation is strongly correlated with the size of the spin-orbit splitting, and that parameter sets which give roughly the correct value for this splitting provide the best agreement with the quadrupole moments in the s-d shell. Finally, for closed shell +/- 1 nuclei, it was shown that the self-consistent calculations are able to reproduce the experimental magnetic moments. This was not possible in relativistic calculations which include only the effects of the valence orbital
Multiple phonon excitation in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.; Frascaria, N.
1994-01-01
The studies of multiphonon excitations in nuclei are reviewed both from the theoretical and experimental points of view. The presence of giant resonances in nuclei is described in the framework of macroscopic and microscopic models and the relative merits of different probes to excite such states are illustrated. The existence of giant resonances built on excited states is stressed. An exhaustive description of the theoretical estimates of the properties of the multiphonon states is presented. The theory predicts that such multiple collective excitations should closely follow a harmonic pattern. Recent experimental results on the double giant dipole resonance using the (π + π - ) double charge exchange reaction are shown. The status of the search for isoscalar multiphonon excitations by means of the strong nuclear potential produced by heavy ions is presented. Conclusions are drawn and new prospects are discussed. (authors) 293 refs., 67 figs., 8 tabs
Spectroscopy of heavy fissionable nuclei
Indian Academy of Sciences (India)
2015-08-05
Aug 5, 2015 ... A comparison of aligned angular momentum in these nuclei over the range of observed frequencies (up to ¯hω ≈ 0.25 MeV) reveals a possible, small but signifi- cant contribution from j15/2 neutrons in 249Cm, as evidenced from the higher degree of alignment compared to 247Cm over the observed range ...
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
Systematic study on the competition between α-decay and spontaneous fission of superheavy nuclei
Zhang, Y. L.; Wang, Y. Z.
2017-10-01
The competition between α-decay and spontaneous fission (SF) of Z = 112 isotopes are studied. The α-decay half-lives are estimated by the generalized liquid-drop model (GLDM) and several sets of analytic formulas. These formulas include the Royer formula, Viola-Seaborg semiempirical (VSS) formula and universal decay law (UDL). For the SF, its half-lives are calculated by using the Xu, Ren, Karpov and Santhosh formulas. It is shown that the predicted α-decay half-lives by different approaches are more or less identical. However, the SF half-lives are highly sensitive to models. To test the accuracies of different SF formulas, the half-lives of 56 even-even heavy nuclei are calculated by these formulas. By comparing with the experimental data, it is found that the Xu formula is the most accurate one to reproduce the experimental SF half-lives. This allows us to make a systematic prediction on the competition between α-decay and SF of even-even superheavy nuclei (SHN) with Z = 104- 120 by using the Xu formula and the above mentioned models on α-decay. The calculations suggest that 258,260104, 268-276110, 270-280112, 272-286114, 274-294116, 284-302118 and 292-308120 have smaller α-decay half-lives than those of SF. Thus these nuclei can be synthesized and identified via α-decay in the laboratory. In addition, it is observed that N = 162, 178, 184 and 196 may be the submagic or magic numbers. Finally, an extensive study on the possible α-decay chains for Z = 120 isotopes is performed. It is predicted that six sequential α-decay chains can be observed from 292-296120, four α-decay chains from 298120, three α-decay chains from 300,302120, two α-decay chains from 304,306120, and only one α-decay chain from 308120. These nuclei are the most likely candidates to be synthesized experimentally via α-decay in the near future.
Zhao, T. L.; Bao, X. J.; Guo, S. Q.
2018-02-01
Systematic calculations on the α decay half-lives are performed by using three analytical formulas and two semiclassical approaches. For the three analytical formulas, the experimental α decay half-lives and {Q}α values of the 66 reference nuclei have been used to obtain the coefficients. We get only four adjustable parameters to describe α decay half-lives for even-even, odd-A, and odd-odd nuclei. By comparison between the calculated values from ten analytical formulas and experimental data, it is shown that the new universal decay law (NUDL) foumula is the most accurate one to reproduce the experimental α decay half-lives of the superheavy nuclei (SHN). Meanwhile it is found that the experimental α decay half-lives of SHN are well reproduced by the Royer formula although many parameters are contained. The results show that the NUDL formula and the generalized liquid drop model (GLDM2) with consideration of the preformation factor can give fairly equivalent results for the superheavy nuclei.
Isospin asymmetry dependence of the α spectroscopic factor for heavy nuclei
International Nuclear Information System (INIS)
Seif, W. M.; Shalaby, M.; Alrakshy, M. F.
2011-01-01
Both the valence nucleons (holes) and the isospin asymmetry dependencies of the preformation probability of an α-cluster inside parents radioactive nuclei are investigated. The calculations are employed in the framework of the density-dependent cluster model of an α-decay process for the even-even spherical parents nuclei with protons number around the closed shell Z 0 = 82 and neutrons number around the closed shells Z 0 = 82 and Z 0 = 126. The microscopic α-daughter nuclear interaction potential is calculated in the framework of the Hamiltonian energy density approach based on the SLy4 Skyrme-like effective interaction. Also, the calculations based on the realistic effective M3Y-Paris nucleon-nucleon force have been used to confirm the results. The calculations then proceed to find the assault frequency and the α penetration probability within the WKB approximation. The half-lives of the different mentioned α decays are then determined and have been used in turn to find the α spectroscopic factor. We found that the spectroscopic factor increases with increasing the isospin asymmetry of the parent nuclei if they have valence protons and neutrons. When the parent nuclei have neutron or proton holes in addition to the valence protons or neutrons, then the spectroscopic factor is found to decrease with increasing isospin asymmetry. The obtained results show also that the deduced spectroscopic factors follow individual linear behaviors as a function of the multiplication of the valence proton (N p ) and neutron (N n ) numbers. These linear dependencies are correlated with the closed shells core (Z 0 ,N 0 ). The same individual linear behaviors are obtained as a function of the multiplication of N p N n and the isospin asymmetry parameter, N p N n I. Moreover, the whole deduced spectroscopic factors are found to exhibit a nearly general linear trend with the function N p N n /(Z 0 +N 0 ).
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
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
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
International Nuclear Information System (INIS)
Close, F.E.
1988-01-01
The paper concerns some of the ideas underlying quarks and their interactions, the way that quarks build up hadrons, and the extent to which the QCD theory can be applied to phenomena involving nuclei. The article is part of the Proceedings of the International School of Nuclear Physics, Erice, 1987. A description is given of quarks and multiplets. Colour is discussed with respect to: evidence for colour, a non abelian Su(3) theory, the pauli principle at work in hadrons, and spin flavour correlations and magnetic moments. Colour, gluons and the inter quark potential are also examined. (UK)
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
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.
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
Camp, M. G.; Nakao, S.; Kreidenweis, S. M.
2013-12-01
This study employs a new experimental approach to better characterize the hygroscopicity of fractal-like particles. Traditional methods of measuring particle hygroscopicity with a size-resolved Cloud Condensation Nuclei (CCN) set-up require accurate measurement of the dry particle's volume. The relationship between the mobility diameter and the volume is straightforward for a spherical particle, or a slightly irregular particle with a known shape factor, but is not well known for fractal particles. The traditional CCN activity measurement overestimates the amount of solute in a particle when the particle has irregular geometry and thus underestimates hygroscopicity, as measured by the parameter κ developed in Petters and Kreidenweis, 2007. We used a new experimental approach to overcome this challenge: CCN measurements were carried out using wet particles so that the volume of the dry solute does not need to be measured directly. When sufficiently wetted, fractal particles collapse, and the spherical assumption for mobility sizing of the wetted particles is valid. In order to test the wet CCN approach on a fractal particle, iodine oxide particles were generated in a 65 L batch reactor by photolysis of CH2I2 to generate iodine radicals, which subsequently reacted with ozone under dry (RH65%)conditions in two separate series of experiments. The hygroscopicities of generated particles were measured using the traditional dry CCN method and our wet CCN method. For the particles generated under dry conditions, the observed κ for particles measured at low humidity was 0.2, an underestimate, while at RH above 40% κ values were 0.6-0.7, more in line with expectations. The wetted particles' observed higher hygroscopicity was consistent with collapsing of fractal particles at higher RH and was a more accurate determination of their water contents. Particles generated under humid reactor conditions exhibited κ≈0, suggesting the compounds produced via gas phase oxidation
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
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
Yu, Jong-Sung; Yoon, Suk Bon; Lee, Yun Jo; Yoon, Kyung Byung
2005-04-21
In this work, an attempt has been made to modify the shape and nanostructure of core-shell materials, which have been usually generated on the basis of amorphous spherical cores. Novel core-shell silicate particles, each of which consists of a silicalite-1 zeolite crystal core and mesoporous shell (ZCMS), were synthesized for the first time. The ZCMS core-shell particles are unique because they are of pseudohexagonal prismatic shape and have hierarchical porosity of both a uniform microporous core and a mesoporous shell coexisting in a particle framework. The nonspherical bimodal porous core-shell particles were then utilized as templates to fabricate a new carbon replica structure. Interestingly, the pore replication process was carried out only through the mesopores in the shell, and not through the micropores due to the narrower micropore size in the core, resulting in nonspherical carbon nanocases with a hollow core and mesoporous shell (HCMS) structure. Nonspherical silica nanocases with HCMS structure were also generated by replication using the carbon nanocases as templates, which are not possible to synthesize through other synthetic methods. Interestingly, the pseudohexagonal prismatic shape of the zeolite crystals was transferred onto the carbon and silica nanocases.
Quartet correlations in N = Z nuclei induced by realistic two-body interactions
Energy Technology Data Exchange (ETDEWEB)
Sambataro, M. [Istituto Nazionale di Fisica Nucleare - Sezione di Catania, Catania (Italy); Sandulescu, N. [National Institute of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)
2017-03-15
Two variational quartet models previously employed in a treatment of pairing forces are extended to the case of a general two-body interaction. One model approximates the nuclear states as a condensate of identical quartets with angular momentum J = 0 and isospin T = 0 while the other let these quartets to be all different from each other. With these models we investigate the role of alpha-like quartet correlations both in the ground state and in the lowest J = 0, T = 0 excited states of even-even N = Z nuclei in the sd -shell. We show that the ground-state correlations of these nuclei can be described to a good extent in terms of a condensate of alpha-like quartets. This turns out to be especially the case for the nucleus {sup 32}S for which the overlap between this condensate and the shell model wave function is found close to one. In the same nucleus, a similar overlap is found also in the case of the first excited 0{sup +} state. No clear correspondence is observed instead between the second excited states of the quartet models and the shell model eigenstates in all the cases examined. (orig.)
Structures of Superdeforemed States in Nuclei with A~60 Using Two-Parameter Collective Model
Directory of Open Access Journals (Sweden)
Gaballah N.
2015-01-01
Full Text Available Superdeformed (SD states in nuclei in mass region A ∼ 60 − 90 are investigated within the framework of two-parameter formula of Bohr and Motelson model. The concept of γ -ray transition energy E γ over spin (EGOS is used to assign the first order estimation of the bandhead spin. The model parameters and the true spin o f bandhead have been obtained by adopted best fit method in order to obtain a minimum root-mean-square deviation between the calculated and the experimental γ -ray transition energies. The transition energies E γ and the dynamical moment of inertia J (2 for data set include thir- teen SD bands in even-even nuclei are calculated. The result s agree with experimental data well. The behavior of J (2 as a function of rotational frequency ~ ω are discussed. By using the calculated bandhead moment of inertia, the predicted quadrupole moments of the studied yrast SD bands are calculated and agree well with the observed data.
Directory of Open Access Journals (Sweden)
Xuhao Wang
2017-01-01
Full Text Available The 7R 6-DOF robots with hollow nonspherical wrist have been proven more suitable for spray painting applications. However, the inverse kinematics of this kind of robot is still imperfect due to the coupling between position and orientation of the end-effector (EE. In this paper, a new and efficient algorithm for the inverse kinematics of a 7R 6-DOF robot is proposed. The proposed inverse kinematics algorithm is a two-step method. The geometry of the 7R 6-DOF robot is analyzed. A comparison between the 7R 6-DOF robot and the well-known equivalent 6R robot is made. Based on this comparison, a rational transformation between these two kinds of robots is constructed. Then the general inverse kinematics algorithm of the equivalent 6R robot is applied to calculate the approximate solutions of the 7R 6-DOF robot, in the first step. The Damped Least-Squares (DLS method is employed to derive the exact solutions, in the second step. The accuracy and efficiency of the algorithm are tested on a 7R 6-DOF painting robot. The results show that the proposed algorithm is more advantageous in the case without an approximate solution, such as the initial point of a continuous trajectory.
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
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.
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)
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.)
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
Structure of neutron-rich nuclei
International Nuclear Information System (INIS)
Nazarewicz, W.; Ploszajczak, M.
2003-01-01
Structure of exotic radioactive nuclei having extreme neutron-to-proton ratios is different from that around the stability line. This short review discusses the progress in modeling of exotic nuclei in the nuclear ''Terra Incognita''. The consistent theoretical description of weakly bound systems requires a synergy between nuclear structure and nuclear reaction methods. (orig.)
RFP for the Comet Nuclei Tour (CONTOUR)
DEFF Research Database (Denmark)
Jørgensen, John Leif; Madsen, Peter Buch; Betto, Maurizio
1999-01-01
This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program.......This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program....
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.)
Partial Dynamical Symmetry in Deformed Nuclei
International Nuclear Information System (INIS)
Leviatan, A.
1996-01-01
We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. copyright 1996 The American Physical Society
Partial Dynamical Symmetry in Deformed Nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)
1996-07-01
We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. {copyright} {ital 1996 The American Physical Society.}
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
A double potential model for neutron halo nuclei
Abbas, Afsar
2003-01-01
It is shown here that loosely bound halo structure of neutron rich nuclei and the ground state spin of single neutron halo nuclei are correlated and are consistently explained if one assumes a double potential shell model for these nuclei.
Felgitsch, Laura; Seifried, Teresa; Winkler, Philipp; Schmale, David, III; Grothe, Hinrich
2017-04-01
While the importance of heterogeneous ice nucleation in the atmosphere is known, we still know very little about the substances triggering these freezing events. Recent findings support the theory that biological ice nuclei (IN) exhibit the ability to play an important role in these processes. Huffman et al. (2013) showed a burst of biological IN over woodlands triggered by rain events. Birch pollen are known to release a high number of efficient IN if incubated in water (Pummer et al. 2012). Therefore birches are of interest in our research on this topic. Plants native to the timberline, such as birch trees, have to cope with very cold climatic conditions, rendering freezing avoidance impossible. These plants trigger freezing in their extracellular spaces to control the freezing process and avoid intracellular freezing, which would have lethal consequences. The plants hereby try to freeze at a temperature well above homogeneous freezing temperatures but still at temperatures low enough to not be effected by brief night frosts. To achieve this, IN are an important tool. The specific objective of our work was to study the potential sources and distribution of IN in birch trees. We collected leaves, fruit, bark, and trunk cores from a series of mature birch trees in Tyrol, Austria at different altitudes and sampling sites. We also collected samples from a birch tree in an urban park in Vienna, Austria. Our data show a sampling site dependence and the distribution of IN throughout the tree. Our data suggest that leaves, bark, and wood of birch can function as a source of IN, which are easily extracted with water. The IN are therefore not restricted to pollen. Hence, the amount of IN, which can be released from birch trees, is tremendous and has been underrated so far. Future work aims to elucidate the nature, contribution, and potential ecological roles of IN from birch trees in different habitats. Huffman, J.A., Prenni, A.J., DeMott, P.J., Pöhlker, C., Mason, R
Kowalczyk, Klaudia; Łokas, Ewa L.; Valluri, Monica
2018-05-01
In our previous work we confirmed the reliability of the spherically symmetric Schwarzschild orbit-superposition method to recover the mass and velocity anisotropy profiles of spherical dwarf galaxies. Here, we investigate the effect of its application to intrinsically non-spherical objects. For this purpose we use a model of a dwarf spheroidal galaxy formed in a numerical simulation of a major merger of two discy dwarfs. The shape of the stellar component of the merger remnant is axisymmetric and prolate which allows us to identify and measure the bias caused by observing the spheroidal galaxy along different directions, especially the longest and shortest principal axis. The modelling is based on mock data generated from the remnant that are observationally available for dwarfs: projected positions and line-of-sight velocities of the stars. In order to obtain a reliable tool while keeping the number of parameters low we parametrize the total mass distribution as a radius-dependent mass-to-light ratio with just two free parameters we aim to constrain. Our study shows that if the total density profile is known, the true, radially increasing anisotropy profile can be well recovered for the observations along the longest axis whereas the data along the shortest axis lead to the inference of an incorrect, isotropic model. On the other hand, if the density profile is derived from the method as well, the anisotropy is always underestimated but the total mass profile is well recovered for the data along the shortest axis whereas for the longest axis the mass content is overestimated.
Kowalczyk, Klaudia; Łokas, Ewa L.; Valluri, Monica
2018-02-01
In our previous work we confirmed the reliability of the spherically symmetric Schwarzschild orbit-superposition method to recover the mass and velocity anisotropy profiles of spherical dwarf galaxies. Here we investigate the effect of its application to intrinsically non-spherical objects. For this purpose we use a model of a dwarf spheroidal galaxy formed in a numerical simulation of a major merger of two disky dwarfs. The shape of the stellar component of the merger remnant is axisymmetric and prolate which allows us to identify and measure the bias caused by observing the spheroidal galaxy along different directions, especially the longest and shortest principal axis. The modelling is based on mock data generated from the remnant that are observationally available for dwarfs: projected positions and line-of-sight velocities of the stars. In order to obtain a reliable tool while keeping the number of parameters low we parametrize the total mass distribution as a radius-dependent mass-to-light ratio with just two free parameters we aim to constrain. Our study shows that if the total density profile is known, the true, radially increasing anisotropy profile can be well recovered for the observations along the longest axis whereas the data along the shortest axis lead to the inference an incorrect, isotropic model. On the other hand, if the density profile is derived from the method as well, the anisotropy is always underestimated but the total mass profile is well recovered for the data along the shortest axis whereas for the longest axis the mass content is overestimated.
Symmetry and Phase Transitions in Nuclei
International Nuclear Information System (INIS)
Iachello, F.
2009-01-01
Phase transitions in nuclei have received considerable attention in recent years, especially after the discovery that, contrary to expectations, systems at the critical point of a phase transition display a simple structure. In this talk, quantum phase transitions (QPT), i.e. phase transitions that occur as a function of a coupling constant that appears in the quantum Hamiltonian, H, describing the system, will be reviewed and experimental evidence for their occurrence in nuclei will be presented. The phase transitions discussed in the talk will be shape phase transitions. Different shapes have different symmetries, classified by the dynamic symmetries of the Interacting Boson Model, U(5), SU(3) and SO(6). Very recently, the concept of Quantum Phase Transitions has been extended to Excited State Quantum Phase Transitions (ESQPT). This extension will be discussed and some evidence for incipient ESQPT in nuclei will be presented. Systems at the critical point of a phase transition are called 'critical systems'. Approximate analytic formulas for energy spectra and other properties of 'critical nuclei', in particular for nuclei at the critical point of the second order U(5)-SO(6) transition, called E(5), and along the line of first order U(5)-SU(3) transitions, called X(5), will be presented. Experimental evidence for 'critical nuclei' will be also shown. Finally, the microscopic derivation of shape phase transitions in nuclei within the framework of density functional methods will be briefly discussed.(author)
Evolution of planetary nebula nuclei
International Nuclear Information System (INIS)
Shaw, R.A.
1985-01-01
The evolution of planetary nebula nuclei (PNNs) is examined with the aid of the most recent available stellar evolution calculations and new observations of these objects. Their expected distribution in the log L-log T plane is calculated based upon the stellar evolutionary models of Paczynski, Schoenberner and Iben, the initial mass function derived by Miller and Scalo, and various assumptions concerning mass loss during post-main sequence evolution. The distribution is found to be insensitive both to the assumed range of main-sequence progenitor mass and to reasonable variations in the age and the star forming history of the galactic disk. Rather, the distribution is determined by the strong dependence of the rate of stellar evolution upon core mass, the steepness of the initial mass function, and to a lesser extent the finite lifetime of an observable planetary nebula. The theoretical distributions are rather different than any of those inferred from earlier observations. Possible observational selection effects that may be responsible are examined, as well as the intrinsic uncertainties associated with the theoretical model predictions. An extensive photometric and smaller photographic survey of southern hemisphere planetary nebulae (PNs) is presented
International Nuclear Information System (INIS)
Beck, Christian
2012-01-01
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 second volume follows the successful Lect. Notes Phys. 818 (Vol.1), and comprises six extensive lectures covering the following topics: - Microscopic cluster models - Neutron halo and break-up reactions - Break-up reaction models for two- and three-cluster projectiles - Clustering effects within the di-nuclear model - Nuclear alpha-particle condensates - Clusters in nuclei: experimental perspectives By promoting new ideas and developments while retaining a pedagogical style of presentation throughout, these lectures will serve as both a reference and an advanced teaching manual for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)
Coupled-cluster computations of atomic nuclei.
Hagen, G; Papenbrock, T; Hjorth-Jensen, M; Dean, D J
2014-09-01
In the past decade, coupled-cluster theory has seen a renaissance in nuclear physics, with computations of neutron-rich and medium-mass nuclei. The method is efficient for nuclei with product-state references, and it describes many aspects of weakly bound and unbound nuclei. This report reviews the technical and conceptual developments of this method in nuclear physics, and the results of coupled-cluster calculations for nucleonic matter, and for exotic isotopes of helium, oxygen, calcium, and some of their neighbors.
Hot nuclei: high temperatures, high angular momenta
International Nuclear Information System (INIS)
Guerreau, D.
1991-01-01
A review is made of the present status concerning the production of hot nuclei above 5 MeV temperature, concentrating mainly on the possible experimental evidences for the attainment of a critical temperature, on the existence of dynamical limitations to the energy deposition and on the experimental signatures for the formation of hot spinning nuclei. The data strongly suggest a nuclear disassembly in collisions involving very heavy ions at moderate incident velocities. Furthermore, hot nuclei seem to be quite stable against rotation on a short time scale. (author) 26 refs.; 12 figs
Olson, William S.; Tian, Lin; Grecu, Mircea; Kuo, Kwo-Sen; Johnson, Benjamin; Heymsfield, Andrew J.; Bansemer, Aaron; Heymsfield, Gerald M.; Wang, James R.; Meneghini, Robert
2016-01-01
In this study, two different particle models describing the structure and electromagnetic properties of snow are developed and evaluated for potential use in satellite combined radar-radiometer precipitation estimation algorithms. In the first model, snow particles are assumed to be homogeneous ice-air spheres with single-scattering properties derived from Mie theory. In the second model, snow particles are created by simulating the self-collection of pristine ice crystals into aggregate particles of different sizes, using different numbers and habits of the collected component crystals. Single-scattering properties of the resulting nonspherical snow particles are determined using the discrete dipole approximation. The size-distribution-integrated scattering properties of the spherical and nonspherical snow particles are incorporated into a dual-wavelength radar profiling algorithm that is applied to 14- and 34-GHz observations of stratiform precipitation from the ER-2 aircraft-borne High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) radar. The retrieved ice precipitation profiles are then input to a forward radiative transfer calculation in an attempt to simulate coincident radiance observations from the Conical Scanning Millimeter-Wave Imaging Radiometer (CoSMIR). Much greater consistency between the simulated and observed CoSMIR radiances is obtained using estimated profiles that are based upon the nonspherical crystal/aggregate snow particle model. Despite this greater consistency, there remain some discrepancies between the higher moments of the HIWRAP-retrieved precipitation size distributions and in situ distributions derived from microphysics probe observations obtained from Citation aircraft underflights of the ER-2. These discrepancies can only be eliminated if a subset of lower-density crystal/aggregate snow particles is assumed in the radar algorithm and in the interpretation of the in situ data.
Pollack, J. B.; Cuzzi, J. N.
1978-01-01
Mie theory, which is generally used to describe the scattering behavior of particles at a certain wavelength, is only rigorously correct for spherical particles. Particles found as atmospheric constituents, with the exception of cloud droplets, are, however, decidedly nonspherical. An investigation is, therefore, conducted regarding the significant ways in which the scattering behavior of irregularly shaped particles differs from that of spheres. A systematic method is formulated for treating the real scalar scattering behavior. A description is presented of a new semiempirical theory based on simple physical principles and data obtained in laboratory measurements, which successfully reproduces the single scattering phase function for a wide range of particle shapes, sizes, and refractive indices.
Parton distributions in nuclei: Quagma or quagmire
Energy Technology Data Exchange (ETDEWEB)
Close, F.E.
1988-01-01
The emerging information on the way quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed. Particular emphasis is placed on Drell-Yan and /psi/ production on nuclei and caution against premature use of these as signals for quagma in heavy-ion collisions. If we are to identify the formation of quark-gluon plasma in heavy-ion collisions by changes in the production rates for /psi/ relative to Drell-Yan lepton pairs, then it is important that we first understand the ''intrinsic'' changes in parton distributions in nuclei relative to free nucleons. So, emerging knowledge on how quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed, and the emerging theoretical concensus is briefly summarized.
New vistas of exotic heavy nuclei
International Nuclear Information System (INIS)
Cocks, J.F.C.; Butler, P.A.
1997-01-01
We report studies of examples of reflection-asymmetric nuclei which are difficult to access using compound nucleus reactions. The most octupole deformed nuclei should be uranium isotopes with N ∼ 132; preliminary measurements of these very fissile nuclei suggest that they are within reach of current spectroscopic techniques. The octupole radium isotopes with N > 132 and radon isotopes are not accessible by reactions employing stable targets and beams; we have shown that multinucleon transfer reactions can populate these nuclei with sufficient yield for their structure to be determined. We report high spin studies in 218,220,222 Rn and 222,224,226 Ra which reveal upbending effects in this mass region for the first time and show that the electric dipole moment is constant with spin. (author)
Superheavy nuclei: a relativistic mean field outlook
International Nuclear Information System (INIS)
Afanasjev, A.V.
2006-01-01
The analysis of quasi-particle spectra in the heaviest A∼250 nuclei with spectroscopic data provides an additional constraint for the choice of effective interaction for the description of superheavy nuclei. It strongly suggests that only the parametrizations which predict Z = 120 and N = 172 as shell closures are reliable for superheavy nuclei within the relativistic mean field theory. The influence of the central depression in the density distribution of spherical superheavy nuclei on the shell structure is studied. A large central depression produces large shell gaps at Z = 120 and N = 172. The shell gaps at Z = 126 and N = 184 are favoured by a flat density distribution in the central part of the nucleus. It is shown that approximate particle number projection (PNP) by means of the Lipkin-Nogami (LN) method removes pairing collapse seen at these gaps in the calculations without PNP
Nuclear Computational Low Energy Initiative (NUCLEI)
Energy Technology Data Exchange (ETDEWEB)
Reddy, Sanjay K. [University of Washington
2017-08-14
This is the final report for University of Washington for the NUCLEI SciDAC-3. The NUCLEI -project, as defined by the scope of work, will develop, implement and run codes for large-scale computations of many topics in low-energy nuclear physics. Physics to be studied include the properties of nuclei and nuclear decays, nuclear structure and reactions, and the properties of nuclear matter. The computational techniques to be used include Quantum Monte Carlo, Configuration Interaction, Coupled Cluster, and Density Functional methods. The research program will emphasize areas of high interest to current and possible future DOE nuclear physics facilities, including ATLAS and FRIB (nuclear structure and reactions, and nuclear astrophysics), TJNAF (neutron distributions in nuclei, few body systems, and electroweak processes), NIF (thermonuclear reactions), MAJORANA and FNPB (neutrino-less double-beta decay and physics beyond the Standard Model), and LANSCE (fission studies).
Observation of spinodal decomposition in nuclei?
International Nuclear Information System (INIS)
Guarnera, A.; Colonna, M.; Chomaz, Ph.
1996-01-01
Multifragmentation in heavy ion collisions is investigated in the framework of mean-field theory, in order to gain information on the equation of state of nuclear matter. Spinodal decomposition in nuclei is studied. (K.A.)
Infrared Observations of Cometary Dust and Nuclei
Lisse, Carey
2004-01-01
This bibliography lists citations for publications published under the grant. Subjects of the publications include cometary dust, instellar and interplanetary dust, comet nuclei and comae, Comet Hale-Bopp, infrared observations of comets, mass loss, and comet break-up.
Critical-Point Structure in Finite Nuclei
International Nuclear Information System (INIS)
Leviatan, A.
2006-01-01
Properties of quantum shape-phase transitions in finite nuclei are considered in the framework of the interacting boson model. Special emphasis is paid to the dynamics at the critical-point of a general first-order phase transition
Electro-magnetic properties of heavy nuclei
International Nuclear Information System (INIS)
Otsuka, Takaharu
1989-01-01
Two topics of electro-magnetic properties of heavy nuclei are discussed. The first topic is the M1 excitation from well-deformed heavy nuclei, and the other is the sudden increase of the isotope shift as a function of N in going away from the closed shell. These problems are considered in terms of the particle-number projected (Nilsson-) BCS calculation. (author)
High energy particle interactions with nuclei
International Nuclear Information System (INIS)
Czyz, W.
1978-01-01
The recent interest in multiparticle production processes on nuclei was triggered by re-discovering their 'enigmatic simplicity' which has been known to cosmic ray physicists for over 20 years: the mean multiplicity and angular distributions of relativistic secondaries produced on nuclei do not differ markedly from what emerges from p-p collisions. The author considers how such reactions may provide a way of obtaining details of hadron structure. (Auth.)
Nuclei far off the stability line
International Nuclear Information System (INIS)
Fenyes, T.
1978-01-01
Theoretical and experimental aspects of the formation of some ''exotic'' nuclei far off the stability line were reviewed in addition to the relevant results of research in this field. Results in beta- and gamma-ray spectroscopy, heavy-ion-spectroscopy, achievements in the fields of measuring the atomic mass, the moment, and the radius of the nuclei as well as some astronomical aspects were described. (Z.P.)
Proton radioactivity from proton-rich nuclei
International Nuclear Information System (INIS)
Guzman, F.; Goncalves, M.; Tavares, O.A.P.; Duarte, S.B.; Garcia, F.; Rodriguez, O.
1999-03-01
Half-lives for proton emission from proton-rich nuclei have been calculated by using the effective liquid drop model of heavy-particle decay of nuclei. It is shown that this model is able to offer results or spontaneous proton-emission half-life-values in excellent agreement with the existing experimental data. Predictions of half-life-values for other possible proton-emission cases are present for null orbital angular momentum. (author)
Oscillations of atomic nuclei in crystals
Vdovenkov, V. A.
2002-01-01
Oscillations of atomic nuclei in crystals are considered in this paper. It is shown that elastic nuclei oscillations relatively electron envelops (inherent, I-oscillations) and waves of such oscillations can exist in crystals at adiabatic condition. The types and energy quantums of I-oscillations for different atoms are determined. In this connection the adiabatic crystal model is offered. Each atom in the adiabatic model is submitted as I-oscillator whose stationary oscillatory terms are sho...
Hot nuclei, limiting temperatures and excitation energies
International Nuclear Information System (INIS)
Peter, J.
1986-09-01
Hot fusion nuclei are produced in heavy ion collisions at intermediate energies (20-100 MeV/U). Information on the maximum excitation energy per nucleon -and temperatures- indicated by the experimental data is compared to the predictions of static and dynamical calculations. Temperatures around 5-6 MeV are reached and seem to be the limit of formation of thermally equilibrated fusion nuclei
Thomas Fermi model of finite nuclei
International Nuclear Information System (INIS)
Boguta, J.; Rafelski, J.
1977-01-01
A relativistic Thomas-Fermi model of finite-nuclei is considered. The effective nuclear interaction is mediated by exchanges of isoscalar scalar and vector mesons. The authors include also a self-interaction of the scalar meson field and the Coulomb repulsion of the protons. The parameters of the model are constrained by the average nuclear properties. The Thomas-Fermi equations are solved numerically for finite, stable nuclei. The particular case of 208 82 Pb is considered in more detail. (Auth.)
Parity and time reversal violation in nuclei
International Nuclear Information System (INIS)
Adelberger, E.G.; Washington Univ., Seattle
1987-01-01
The current status of investigations into parity (P) and time-reversal (T) violation in nuclei is considered. Nuclear P-violation is an expected consequence of the standard model. It has been observed in a wide variety of nuclei (from A=2, to A∼ 200) by using a wide variety of reactions (reactions induced by polarized neutrons and polarized protons, γ-decay, α-decay, and (α, γ) reactions)
Major new sources of biological ice nuclei
Moffett, B. F.; Hill, T.; Henderson-Begg, S. K.
2009-12-01
Almost all research on biological ice nucleation has focussed on a limited number of bacteria. Here we characterise several major new sources of biogenic ice nuclei. These include mosses, hornworts, liverworts and cyanobacteria. Ice nucleation in the eukaryotic bryophytes appears to be ubiquitous. The temperature at which these organisms nucleate is that at which the difference in vapour pressure over ice and water is at or close to its maximum. At these temperatures (-8 to -18 degrees C) ice will grow at the expense of supercooled water. These organisms are dependent for their water on occult precipitation - fog, dew and cloudwater which by its nature is not collected in conventional rain gauges. Therefore we suggest that these organism produce ice nuclei as a water harvesting mechanism. Since the same mechanism would also drive the Bergeron-Findeisen process, and as moss is known to become airborne, these nuclei may have a role in the initiation of precipitation. The properties of these ice nuclei are very different from the well characterised bacterial nuclei. We will also present DNA sequence data showing that, although related, the proteins responsible are only very distantly related to the classical bacterial ice nuclei.
The anatomy of the vestibular nuclei.
Highstein, Stephen M; Holstein, Gay R
2006-01-01
The vestibular portion of the eighth cranial nerve informs the brain about the linear and angular movements of the head in space and the position of the head with respect to gravity. The termination sites of these eighth nerve afferents define the territory of the vestibular nuclei in the brainstem. (There is also a subset of afferents that project directly to the cerebellum.) This chapter reviews the anatomical organization of the vestibular nuclei, and the anatomy of the pathways from the nuclei to various target areas in the brain. The cytoarchitectonics of the vestibular brainstem are discussed, since these features have been used to distinguish the individual nuclei. The neurochemical phenotype of vestibular neurons and pathways are also summarized because the chemical anatomy of the system contributes to its signal-processing capabilities. Similarly, the morphologic features of short-axon local circuit neurons and long-axon cells with extrinsic projections are described in detail, since these structural attributes of the neurons are critical to their functional potential. Finally, the composition and hodology of the afferent and efferent pathways of the vestibular nuclei are discussed. In sum, this chapter reviews the morphology, chemoanatomy, connectivity, and synaptology of the vestibular nuclei.
Kim, Jae Min; Kim, Man-Deuk; Han, Kichang; Muqmiroh, Lailatul; Kim, Seung Up; Kim, Gyoung Min; Kwon, Joonho; Park, Sung Il; Won, Jong Yun; Lee, Do Yun
2017-05-01
To evaluate the effect of bariatric arterial embolization (BAE) with non-spherical polyvinyl alcohol (PVA) particles on systemic ghrelin levels, weight change, and gastric ulceration risk in a swine model. From March 2014 to February 2015, ten healthy swine were used in the study (mean weight 31.5 kg; range 24.0-41.5 kg). The animals were randomly assigned to two groups: the embolized group (n = 5) in which BAE was performed and the control group (n = 5). In the embolized group, BAE was performed by selectively infusing 150-250 or 50-150 μm PVA into the gastric arteries that supplied the fundus of the stomach. In the control group, a sham procedure was performed with saline infusion. Plasma ghrelin levels were prospectively obtained at baseline and every 2 weeks thereafter. Endoscopy was performed 3 weeks after BAE to see whether any gastric ulcer occurred. To determine the durability of the occluded arteries, repeated celiac trunk angiography was performed 8 weeks after BAE. Then, all the swine were killed and necropsies were performed. The mean post-procedure ghrelin value decreased by 370.0 pg/mL in the embolized group at week 3 (mean 536.0 ± 334.3 pg/mL) and week 5 (mean 515.0 ± 150.0 pg/mL, p ghrelin levels were not significantly decreased between the embolized and control groups. There was a significant body weight change as follows: 35.1 ± 9.5 to 46.6 ± 15.7 kg and 31.8 ± 5.8 to 41.2 ± 6.6 kg at baseline and endpoint in the control and embolized groups, respectively (p ghrelin levels in embolized animals, but levels are not significantly different compared to controls. Stomach ulcerations were identified in 60% of the embolized animals.
Structure of light neutron-rich nuclei through Coulomb dissociation
Indian Academy of Sciences (India)
The physics of exotic nuclei has attracted much interest during the past decade. The prop- erties of nuclei with large neutron excess have turned out to be very different compared to those of stable nuclei in many respects. One outstanding observation in exotic nuclei is the halo structure. The halo structure arises from the ...
Adipocyte nuclei captured from VAT and SAT.
Ambati, Suresh; Yu, Ping; McKinney, Elizabeth C; Kandasamy, Muthugapatti K; Hartzell, Diane; Baile, Clifton A; Meagher, Richard B
2016-01-01
Obesity-related comorbidities are thought to result from the reprogramming of the epigenome in numerous tissues and cell types, and in particular, mature adipocytes within visceral and subcutaneous adipose tissue, VAT and SAT. The cell-type specific chromatin remodeling of mature adipocytes within VAT and SAT is poorly understood, in part, because of the difficulties of isolating and manipulating large fragile mature adipocyte cells from adipose tissues. We constructed MA-INTACT (Mature Adipocyte-Isolation of Nuclei TAgged in specific Cell Types) mice using the adiponectin (ADIPOQ) promoter (ADNp) to tag the surface of mature adipocyte nuclei with a reporter protein. The SUN1mRFP1Flag reporter is comprised of a fragment of the nuclear transmembrane protein SUN1, the fluorescent protein mRFP1, and three copies of the Flag epitope tag. Mature adipocyte nuclei were rapidly and efficiently immuno-captured from VAT and SAT (MVA and MSA nuclei, respectively), of MA-INTACT mice. MVA and MSA nuclei contained 1,000 to 10,000-fold higher levels of adipocyte-specific transcripts, ADIPOQ, PPARg2, EDNRB, and LEP, relative to uncaptured nuclei, while the latter expressed higher levels of leukocyte and endothelial cell markers IKZF1, RETN, SERPINF1, SERPINE1, ILF3, and TNFA. MVA and MSA nuclei differentially expressed several factors linked to adipogenesis or obesity-related health risks including CEBPA, KLF2, RETN, SERPINE1, and TNFA. The various nuclear populations dramatically differentially expressed transcripts encoding chromatin remodeler proteins regulating DNA cytosine methylation and hydroxymethylation (TETs, DNMTs, TDG, GADD45s) and nucleosomal histone modification (ARID1A, KAT2B, KDM4A, PRMT1, PRMT5, PAXIP1). Remarkably, MSA and MVA nuclei expressed 200 to 1000-fold higher levels of thermogenic marker transcripts PRDM16 and UCP1. The MA-INTACT mouse enables a simple way to perform cell-type specific analysis of highly purified mature adipocyte nuclei from VAT and SAT
Pollen grains are efficient cloud condensation nuclei
Energy Technology Data Exchange (ETDEWEB)
Pope, F D, E-mail: fdp21@cam.ac.uk [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)
2010-10-15
This letter presents a laboratory study investigating the ability of pollen grains to act as cloud condensation nuclei. The hygroscopicity of pollen is measured under subsaturated relative humidities using an electrodynamic balance. It is found, along with other results, that pollen exhibits bulk uptake of water under subsaturated conditions. Through the use of an environmental scanning electron microscope it was observed that the surface of pollen is wettable at high subsaturated humidities. The hygroscopic response of the pollen to subsaturated relative humidities is parametrized using {kappa}-Koehler theory and values of the parameter {kappa} for pollen are between 0.05 and 0.1. It is found that while pollen grains are only moderately hygroscopic, they can activate at critical supersaturations of 0.001% and lower, and thus pollen grains will readily act as cloud condensation nuclei. While the number density of pollen grains is too low for them to represent a significant global source of cloud condensation nuclei, the large sizes of pollen grains suggest that they will be an important source of giant cloud condensation nuclei. Low temperature work using the environmental scanning electron microscope indicated that pollen grains do not act as deposition ice nuclei at temperatures warmer than - 15 deg. C.
Stability and production of superheavy nuclei
International Nuclear Information System (INIS)
Moeller, P.; Los Alamos National Lab., NM; Nix, J.R.
1997-01-01
Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number Z increases, because of the disruptive effect of the long-range Coulomb force. However, in the region just beyond Z = 100 magic proton and neutron numbers and the associated shell structure enhances nuclear stability sufficient to allow observation of additional nuclei. Some thirty years ago it was speculated that an island of spherical, relatively stable superheavy nuclei would exist near the next doubly magic proton-neutron combination beyond 208 Pb, that is, at proton number Z 114 and neutron number N = 184. Theory and experiment now show that there also exists a rock of stability in the vicinity of Z = 110 and N = 162 between the actinide region, which previously was the end of the peninsula of known elements, and the predicted island of spherical superheavy nuclei slightly southwest of the magic numbers Z = 114 and N = 184. The authors review here the stability properties of the heavy region of nuclei. Just as the decay properties of nuclei in the heavy region depend strongly on shell structure, this structure also dramatically affects the fusion entrance channel. The six most recently discovered new elements were all formed in cold-fusion reactions. They discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation
Fast neutron inelastic scattering from nuclei
International Nuclear Information System (INIS)
Lachkar, J.
1978-01-01
The need for accurate values of inelastic scattering cross sections appears when the requests for neutron data for reactors and other applied purposes are considered. These requests are partly related to values for spherical nuclei, well studied over many years. These studies were extensively considered in two review papers presented, in 1976, at the International Conference on the Interactions of Neutrons with nuclei. Other requests are related to vibrational and rotational nuclei, and relevant studies have been recently performed. The quality of these investigations and the large number of recent results have lead to concentration on them as the topic of the present review. The constant improvements of the experimental techniques permits precise measurements of inelastic scattering cross sections to the first excited levels over a range of incident energies, such that different reactions mechanisms are predominant in different parts of that range of energies. Quadrupole, hexadecapole and octupole deformation parameters of the target nuclei can be deduced from the data using phenomenological models. The successful application of the analysis over the range of energies leads to the conclusion that reliable information on the shape of the nuclei has been derived. The validity of the various models, which include direct interaction and compound nucleus reaction mechanisms, is discussed in connection with analyses of recent experiments. (author) [fr
Training nuclei detection algorithms with simple annotations
Directory of Open Access Journals (Sweden)
Henning Kost
2017-01-01
Full Text Available Background: Generating good training datasets is essential for machine learning-based nuclei detection methods. However, creating exhaustive nuclei contour annotations, to derive optimal training data from, is often infeasible. Methods: We compared different approaches for training nuclei detection methods solely based on nucleus center markers. Such markers contain less accurate information, especially with regard to nuclear boundaries, but can be produced much easier and in greater quantities. The approaches use different automated sample extraction methods to derive image positions and class labels from nucleus center markers. In addition, the approaches use different automated sample selection methods to improve the detection quality of the classification algorithm and reduce the run time of the training process. We evaluated the approaches based on a previously published generic nuclei detection algorithm and a set of Ki-67-stained breast cancer images. Results: A Voronoi tessellation-based sample extraction method produced the best performing training sets. However, subsampling of the extracted training samples was crucial. Even simple class balancing improved the detection quality considerably. The incorporation of active learning led to a further increase in detection quality. Conclusions: With appropriate sample extraction and selection methods, nuclei detection algorithms trained on the basis of simple center marker annotations can produce comparable quality to algorithms trained on conventionally created training sets.
Electron scattering and reactions from exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Karataglidis, S. [University of Johannesburg, Department of Physics, Auckland Park (South Africa); University of Melbourne, School of Physics, Victoria (Australia)
2017-04-15
The SCRIT and FAIR/ELISe experiments are the first to attempt to measure directly electron scattering form factors from nuclei far from stability. This will give direct information for the (one-body) charge densities of those systems, about which there is little information available. The SCRIT experiment will be taking data for medium-mass exotic nuclei, while the electron-ion collider at ELISe, when constructed, will be able to measure form factors for a wide range of exotic nuclei, as available from the radioactive ion beams produced by the FAIR experiment. Other facilities are now being proposed, which will also consider electron scattering from exotic nuclei at higher energies, to study short-range correlations in exclusive reactions. This review will consider all available information concerning the current status (largely theoretical) of electron scattering from exotic nuclei and, where possible, complement such information with equivalent information concerning the neutron densities of those exotic systems, as obtained from intermediate energy proton scattering. The issue of long- and short-range correlations will be discussed, and whether extending such studies to the exotic sector will elicit new information. (orig.)
Towards the island of superheavy stability - Prompt spectroscopy of 246Fm and 256Rf nuclei
International Nuclear Information System (INIS)
Piot, J.
2010-10-01
The region of trans-fermium nuclei (Z = 100 to 104) is the last region of the nuclides chart to be accessible to spectroscopic measurements. It therefore provides the ultimate anchor points for nuclear models. This region also lies on the path of the alpha-decay chains of the super-heavy elements. This region represents the limit of today's spectroscopic capabilities. It therefore requires technological developments in order to overcome these limits. My thesis focuses on various aspects of the spectroscopy of trans-fermium nuclei. I took part in the development of the TNT2D digital acquisition cards for germanium detectors. I validated their use on the gamma-ray spectrometer JUROGAM during an in-beam experiment and demonstrated the gain compared to an analogue acquisition system. These tests were part of the developments needed to secure a study of the prompt spectroscopy of 256 Rf. The preparation of this experiment also lead me to work on the development of a 50 Ti beam. For that purpose, I studied and tested the use of titanium organo-metallic compounds compatible with the MIVOC technique. In parallel, I studied the use of metallic and oxide titanium pellets with an inductive oven newly developed at the University of Jyvaeskylae. In addition to these developments, I had the opportunity to study the in-beam prompt spectroscopy of 246 Fm at the University of Jyvaeskylae. The measurements yielded a rotational band built on the ground state of 246 Fm. This band has been observed up to the level 16 + and shows a behaviour quite similar to the neighbouring even-even isotopes, except for the top of the band for which a wider statistics is necessary in order to conclude. (author)
Critical and shape-unstable nuclei
Cailliau, M; Husson, J P; Letessier, J; Mang, H J
1973-01-01
The authors' experimental work on the decay of neutron deficient mercury osmium nuclei, some other studies at ISOLDE (CERN) and their first theoretical analysis show that the nuclei around /sup 186/Pt (Z=78, N=108) are at the limit of spherical, oblate, prolate nuclei, have (the even one) their first 0/sup +/ excited states at very low energy; quasi- rotational bands are associated to these states. The energy of this O/sup +/ state in /sup 186-/Pt deviate from the Kumar value: angular shape instability is not enough to explain this result. The authors look at radial shape and pairing fluctuations. The position of the 4p-4n state must also be known. (0 refs).
Structure and reactions of light exotic nuclei
International Nuclear Information System (INIS)
Suzuki, Y.; Yabana, Y.; Lovas, R.G.; Varga, K.
1998-01-01
With the advent of radioactive beams, light exotic nuclei have come to the focus of a great number of investigations. The most prominent phenomena found are the neutron halos. A fundamental and yet feasible microscopic approach has been developed to the description of light exotic nuclei. A comprehensive and didactically balanced review of the structure and reaction theory of light exotic nuclei is being developed. This general structure theory has been written up. This is followed by a brief review of cluster models, and that paves the way before introducing the multicluster approximation. That is the apt point to clarify the relationship of the microscopic multicluster approach to other microscopic approaches and to macroscopic models. The structure theory part is then completed with a review of calculations for actual cases. (K.A.)
Reflections on cavitation nuclei in water
DEFF Research Database (Denmark)
Mørch, Knud Aage
2007-01-01
to explaining why the tensile strength of water varies so dramatically between the experiments reported. A model for calculation of the critical pressure of skin-covered free gas bubbles as well as that of interfacial gaseous nuclei covered by a skin is presented. This model is able to bridge the apparently......The origin of cavitation bubbles, cavitation nuclei, has been a subject of debate since the early years of cavitation research. This paper presents an analysis of a representative selection of experimental investigations of cavitation inception and the tensile strength of water. At atmospheric...... pressure, the possibility of stabilization of free gas bubbles by a skin has been documented, but only within a range of bubble sizes that makes them responsible for tensile strengths up to about 1.5 bar, and values reaching almost 300 bar have been measured. However, cavitation nuclei can also be harbored...
Superscaling and nucleon momentum distributions in nuclei
International Nuclear Information System (INIS)
Antonov, A.
2005-01-01
The scaling functions f(ψ ' ) and F(y) from the ψ ' - and y-scaling analyses of inclusive electron scattering from nuclei are constructed within the Coherent Density Fluctuation Model (CDFM) using its two equivalent formulations based on either the local density or the nucleon momentum distribution (NMD). The approach is a natural extension of the relativistic Fermi-gas model to finite realistic nuclear systems. The calculations show that the high-momentum components of NMD in the CDFM and their similarity for different nuclei lead to quantitative description of the super-scaling phenomenon and to a good agreement with the experimental data for y ' ' ' - and y-scaling are informative for NMDs at momenta not larger than 2.0-2.5 fm -1 . The work shows the role of both basic quantities, the momentum and density distributions, for the explanation of super-scaling in inclusive electron scattering from nuclei
Energy Technology Data Exchange (ETDEWEB)
Kim, Jae Min; Kim, Man-Deuk, E-mail: mdkim@yuhs.ac; Han, Kichang; Muqmiroh, Lailatul [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Severance Hospital (Korea, Republic of); Kim, Seung Up [Yonsei University College of Medicine, Department of Internal Medicine, Severance Hospital (Korea, Republic of); Kim, Gyoung Min; Kwon, Joonho; Park, Sung Il; Won, Jong Yun; Lee, Do Yun [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Severance Hospital (Korea, Republic of)
2017-05-15
PurposeTo evaluate the effect of bariatric arterial embolization (BAE) with non-spherical polyvinyl alcohol (PVA) particles on systemic ghrelin levels, weight change, and gastric ulceration risk in a swine model.Materials and MethodsFrom March 2014 to February 2015, ten healthy swine were used in the study (mean weight 31.5 kg; range 24.0–41.5 kg). The animals were randomly assigned to two groups: the embolized group (n = 5) in which BAE was performed and the control group (n = 5). In the embolized group, BAE was performed by selectively infusing 150–250 or 50–150 μm PVA into the gastric arteries that supplied the fundus of the stomach. In the control group, a sham procedure was performed with saline infusion. Plasma ghrelin levels were prospectively obtained at baseline and every 2 weeks thereafter. Endoscopy was performed 3 weeks after BAE to see whether any gastric ulcer occurred. To determine the durability of the occluded arteries, repeated celiac trunk angiography was performed 8 weeks after BAE. Then, all the swine were killed and necropsies were performed.ResultsThe mean post-procedure ghrelin value decreased by 370.0 pg/mL in the embolized group at week 3 (mean 536.0 ± 334.3 pg/mL) and week 5 (mean 515.0 ± 150.0 pg/mL, p < 0.05) relative to baseline (880.0 ± 559.5 pg/mL), respectively, but ghrelin levels were not significantly decreased between the embolized and control groups. There was a significant body weight change as follows: 35.1 ± 9.5 to 46.6 ± 15.7 kg and 31.8 ± 5.8 to 41.2 ± 6.6 kg at baseline and endpoint in the control and embolized groups, respectively (p < 0.05). However, the difference between groups was not significant at endpoint. In the embolized group, ulcerations were identified in three animals (60%) and the recanalization of the embolized arteries was noted on follow-up angiography in three animals (60%), respectively.ConclusionBAE with PVA particles can transiently suppress ghrelin
Medium energy hadron scattering from nuclei
International Nuclear Information System (INIS)
Ginocchio, J.N.; Wenes, G.
1986-01-01
The Glauber approximation for medium energy scattering of hadronic projectiles from nuclei is combined with the interacting boson model of nuclei to produce a transition matrix for elastic and inelastic scattering in algebraic form which includes coupling to all the intermediate states. We present closed form analytic expresions for the transition matrix elements for the three dynamical symmetries of the interacting boson model; that is for, a spherical quadrupole vibrator, a γ unstable rotor, and both prolate and oblate axially symmetric rotors. We give examples of application of this formalism to proton scattering from 154 Sm and 154 Gd. 27 refs., 5 figs., 1 tab
Virtual photon spectra for finite nuclei
International Nuclear Information System (INIS)
Wolynec, E.; Martins, M.N.
1988-01-01
The experimental results of an isochromat of the virtual photon spectrum, obtained by measuring the number of ground-state protons emitted by the 16.28 MeV isobaric analogue state in 90 Zr as a function of electron incident energy in the range 17-105 MeV, are compared with the values predicted by a calculation of the E1 DWBA virtual photon spectra for finite nuclei. It is found that the calculations are in excellent agreement with the experimental results. The DWBA virtual photon spectra for finite nuclei for E2 and M1 multipoles are also assessed. (author) [pt
Maris polarization in neutron-rich nuclei
Shubhchintak; Bertulani, C. A.; Aumann, T.
2018-03-01
We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. In particular, we explore the dependence of the polarization effect on neutron excess and neutron-skin thickness. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon-nucleon interactions and optical potentials and the limitations of the method. Our study implies that polarization variables in (p, 2p) reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.
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
Dissipation and the population of compound nuclei
International Nuclear Information System (INIS)
Thoennessen, M.; Beene, J.R.
1992-01-01
The importance of nuclear dissipative efforts on the formation of compound nuclei is studied with the γ-ray decay of the giant dipole resonance (GDR) built on highly excited states. The compound nuclei 164 Yb, 160 Er, and 110 Sn were produced with very mass-asymmetric and with more mass-symmetric target/projectile combinations. The large deviation from statistical model prediction observed in the γ-ray spectra from the more symmetrically formed 160 Er and 164 Yb can be qualitatively explained within the particle exchange model
Monte Carlo approaches to light nuclei
International Nuclear Information System (INIS)
Carlson, J.
1990-01-01
Significant progress has been made recently in the application of Monte Carlo methods to the study of light nuclei. We review new Green's function Monte Carlo results for the alpha particle, Variational Monte Carlo studies of 16 O, and methods for low-energy scattering and transitions. Through these calculations, a coherent picture of the structure and electromagnetic properties of light nuclei has arisen. In particular, we examine the effect of the three-nucleon interaction and the importance of exchange currents in a variety of experimentally measured properties, including form factors and capture cross sections. 29 refs., 7 figs
Monte Carlo approaches to light nuclei
Energy Technology Data Exchange (ETDEWEB)
Carlson, J.
1990-01-01
Significant progress has been made recently in the application of Monte Carlo methods to the study of light nuclei. We review new Green's function Monte Carlo results for the alpha particle, Variational Monte Carlo studies of {sup 16}O, and methods for low-energy scattering and transitions. Through these calculations, a coherent picture of the structure and electromagnetic properties of light nuclei has arisen. In particular, we examine the effect of the three-nucleon interaction and the importance of exchange currents in a variety of experimentally measured properties, including form factors and capture cross sections. 29 refs., 7 figs.
Selfconsistent theory of Coulomb mixing in nuclei
International Nuclear Information System (INIS)
Pyatov, N.I.
1978-01-01
The theory of isobaric states is considered according to the Coulomb mixing in nuclei. For a given form of the isovestor potential the separable residual interactions are constructed by means of the isotopic invariance principle. The strength parameter of the force is found from a selfconsistency condition. The charge dependent force is represented by the Coulomb effective potential. The theory of the isobaric states is developed using the random phase approximation. The Coulomb mixing effects in the ground and isobaric 0 + states of even-mass nuclei are investigated
Computer Model Of Fragmentation Of Atomic Nuclei
Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.
1995-01-01
High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.
Weak and electromagnetic interactions in nuclei
International Nuclear Information System (INIS)
Klapdor, H.V.
1986-01-01
The International Symposium W.E.I.N. 1986 brought together leading experts in the fields of nuclear and elementary particle physics, astrophysics and cosmology. In addition to current problems in nuclear physics (weak and electromagnetic nuclear properties, electroweak interactions in nuclei, exotic nuclei) this book presents fascinating contributions that arise from the interaction among these fields: lepton number violation and neutrino mass; muon physics; weak interactions and fundamental symmetries; fundamental decays; basic experiments for GUTs; weak interactions and astrophysics; GUTs, SUSYs and the early Universe. The book demonstrates that in this context nuclear physics promises exciting future developments. (orig.)
Structure of neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Nazarewicz, W. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics]|[Oak Ridge National Lab., TN (United States). Physics Div.]|[Warsaw Univ. (Poland). Inst. of Theoretical Physics
1997-11-01
One of the frontiers of today`s nuclear science is the ``journey to the limits``: of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The new data on exotic nuclei are expected to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure of neutron-rich nuclei are discussed from a theoretical perspective.
Structure of neutron-rich nuclei
International Nuclear Information System (INIS)
Nazarewicz, W.; Oak Ridge National Lab., TN; Warsaw Univ.
1997-11-01
One of the frontiers of today's nuclear science is the ''journey to the limits'': of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The new data on exotic nuclei are expected to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure of neutron-rich nuclei are discussed from a theoretical perspective
Study of some odd-mass nuclei with 51 neutrons or 51 protons
International Nuclear Information System (INIS)
Duffait, Roger.
1976-01-01
The level schemes of 93 Mo, 113 Sb, 115 Sb and 119 Sb nuclei were studied. The knowledge of the sup(93m+g)Tc decays was improved. The 2,0 min 113 Te isotope was produced and studied for the first time; two 115 Te isomers with neighbouring half-lives were found and ambiguities on the 115 Te nature cleared up. The sup(119m+g)Te decays were studied with the help of isotopically separated sources and the 119 Sb level scheme was revised. The 93 Mo and 119 Sb level lifetimes were studied using Doppler-shift attenuation method (DSAM) using (p,nγ) reactions at the Van de Graaff accelerator of the University of Lyon. On the whole 16 lifetimes were measured. The experimental results were interpreted in the unified model by intermediate coupling between particle states and the even-even vibrational core; attempts to improve the interpretation by using a semi-microscopical model with the delta surface interaction were made and the two calculations were compared [fr
Manokhin, V. N.; 小田野 直光; 長谷川 明
2001-01-01
(n,np)反応断面積のしきいエネルギーが(n,2n)反応断面積のしきいエネルギーよりも低い偶々核について、(n,1p)反応と(n,np)反応の両者の断面積の励起関数を矛盾なく評価するアプローチについて論じた。(n,2n)及び(n,np)反応断面積の励起関数の最大値の決定においては、Manokhinの系統式を用いるとともに、(n,2n)及び(n,np)反応のしきいエネルギーの差の質量依存性も考慮した。(n,2n)及び(n,np)反応の励起関数の計算には、Manokhinの系統式によって与えられる規格化された励起関数を用いた。いくつかの核種に対する(n,2n)及び(n,np)反応断面積の評価を行い、本研究における手法が妥当であることを明らかにした。...
DNA Measurement of Overlapping Cell Nuclei in Thick Tissue Sections
Directory of Open Access Journals (Sweden)
Liang Ji
1997-01-01
Full Text Available The paper describes an improved image analysis procedure for measuring the DNA content of cell nuclei in thick sections of liver tissue by absorption densitometry. Whereas previous methods only permitted the analysis of isolated nuclei, the new technique enables both isolated and overlapping nuclei to be measured. A 3D segmentation procedure determines whether each object is an isolated nucleus or a pair of overlapping nuclei; in the latter case the combined optical density is redistributed to the individual nuclei. A selection procedure ensures that only complete nuclei are measured.
Enlargement of thalamic nuclei in Tourette syndrome
DEFF Research Database (Denmark)
Miller, Ann M; Bansal, Ravi; Hao, Xuejun
2010-01-01
: Morphological abnormalities in the thalamus, together with the disturbances reported in the sensorimotor cortex, striatum, and globus pallidus, support the hypothesis of a circuitwide disorder within motor pathways in TS. The connectivity and function of the numerous and diverse thalamic nuclei within cortical...... in motor circuits to attenuate the severity of tics....
High energy spin isospin modes in nuclei
International Nuclear Information System (INIS)
Chanfray, G.; Ericson, M.
1984-01-01
The high energy response of nuclei to a spin-isospin excitation is investigated. We show the existence of a strong contrast between the spin transverse and spin longitudinal responses. The second one undergoes a shadow effect in the Δ region and displays the occurrence of the pionic branch
Decay of heavy and superheavy nuclei
Indian Academy of Sciences (India)
2014-03-27
Mar 27, 2014 ... Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 4. Decay of heavy and superheavy nuclei. K P Santhosh. Volume 82 Issue 4 April 2014 ... Author Affiliations. K P Santhosh1. School of Pure and Applied Physics, Kannur University, Swami Anandatheertha Campus, Payyanur 670 327, India ...
Test of Pseudospin Symmetry in Deformed Nuclei
Ginocchio, J. N.; Leviatan, A.; Meng, J.; Zhou, Shan-Gui
2003-01-01
Pseudospin symmetry is a relativistic symmetry of the Dirac Hamiltonian with scalar and vector mean fields equal and opposite in sign. This symmetry imposes constraints on the Dirac eigenfunctions. We examine extensively the Dirac eigenfunctions of realistic relativistic mean field calculations of deformed nuclei to determine if these eigenfunctions satisfy these pseudospin symmetry constraints.
Cloud condensation nuclei from biomass burning
International Nuclear Information System (INIS)
Rogers, C.F.; Hudson, J.G.; Zielinska, B.; Tanner, R.L.; Hallett, J.; Watson, J.G.
1991-01-01
In this work, the authors have analyzed biomass and crude oil smoke samples for ionic and organic species. The cloud condensation nuclei activities of the smoke particles are discussed in terms of the measured chemical compositions of the smoke samples. The implications of biomass burning to global climatic change are discussed
Spectroscopic Studies of Exotic Nuclei at ISOLDE
2002-01-01
Experiment IS50 is designed to: a) Investigate the full range of the @b strength function of heavy (A~$>$~48)~K nuclei b)~Study the decay of isomeric states in n-deficient bromine nuclei (A~=~72 and 70). The heavy K isotopes appeared to have complex decay schemes, including feeding by the @b-decay of levels having open neutron channels (Beta decay energy Q(@b) exceeds neutron binding energy S^n); in addition, a large fraction of the delayed transitions populate excited levels in the daughter nuclei. The allowed @b-decay selects states in the daughter nucleus with wave functions having a large overlap with the initial state. Hence, the @b strength functions, deduced from these deca reveal simple structures correlated to the particle-hole excitation energies in the Ca nuclei. These results are valuable for the application of the shell-model calculations far from stability. The delayed neutron spectra are measured with a large area curved scintillator in coincidence either with high resolution Ge(Li) detectors, ...
Physics of the continuum of borromean nuclei
Energy Technology Data Exchange (ETDEWEB)
Vaagen, J.S.; Rogde, T. [Dept. of Physics, Univ. of Bergen (Norway); Danilin, B.V. [RRC The Kurchatov Inst., Kurchatov, Moscow (Russian Federation); Ershov, S.N. [JINR, Dubna, Moscow (Russian Federation); Thompson, I.J. [Dept. of Physics, Univ. of Surrey, Guildford (United Kingdom); Zhukov, M.V. [Chalmers Univ. of Technology and Goeteborg Univ., Goeteborg (Sweden); RNBT Collaboration
1998-06-01
The continuum states of two-neutron halo nuclei are calculated in the method of hyperspherical harmonics. Using DWIA theory appropriate for dilute halo matter we have probed the structure of the low-lying {sup 6}He continuum via calculations of charge-exchange and inelastic scattering. (orig.)
Fisica degli atomi e dei nuclei
Bernardini, Carlo
1965-01-01
Evidenza della struttura atomica della materia ; le proprietà degli atomi e la meccanica atomica ; gli atomi e le radiazioni elettromagnetiche ; struttura microscopica dello stato gassoso ; struttura microscopica dello stato liquido ; struttura microscopica della stato solido ; proprietà elettriche e magnetiche delle sostanze ; proprietà dei nuclei degli atomi ; le particelle elementari.
Quasars: Active nuclei of young galaxies
Komberg, B. V.
1980-01-01
The hypothetical properties of 'young' galaxies and possible methods of observing them are discussed. It is proposed that star formation first takes place in the central regions of protogalaxies which may appear as quasar-like objects. An evolutionary scheme is outlined in which the radio quasars are transformed in time into the nuclei of radio galaxies.
Parity non-conservation in nuclei
International Nuclear Information System (INIS)
Tadic, D.
1980-01-01
Since parity non-conservation in nuclei is an inescapable consequence of weak interactions this review starts with derivation of the effective weak Hamiltonian which then acts as a perturbation mixing states of the opposite parity in nuclei. The connection between the effective weak Hamiltonian and various models of weak interactions (or quantum flavour dynamics, QFD) and the strong quantum chromodynamics (QCD) is briefly reviewed. The effective weak Hamiltonian serves as an input for determining the weak parity-violating potential. This weak potential is the main tool for connecting elementary particles with nuclear physics. Its derivation is discussed with special attention to one-boson-exchange (rho meson, pion, etc) contributions. Examples of theoretical and semi-empirical weak parity-violating potentials are given. Nuclear physics aspects of parity non-conservation in nuclei are discussed including, the gauge invariance of electromagnetic effects and the parity-violating nucleon-nucleon-photon vertex, two-body problems, processes involving α-particles, photon decays of complex nuclei, parity non-conservation in nuclear scattering, and similar effects. 329 references. (U.K.)
Stability of the spherical form of nuclei
International Nuclear Information System (INIS)
Sabry, A.A.
1976-08-01
An extension of the mass formula for a spherical nucleus in the drop model to include a largely deformed nucleus of different forms is investigated. It is found that although the spherical form is stable under small deformations from equilibrium, there exists for heavier nuclei another more favourable stable form, which can be approximated by two, or three touching prolate ellipsoids of revolution
Properties of semi-infinite nuclei
International Nuclear Information System (INIS)
El-Jaick, L.J.; Kodama, T.
1976-04-01
Several relations among density distributions and energies of semi-infinite and infinite nuclei are iventigated in the framework of Wilets's statistical model. The model is shown to be consistent with the theorem of surface tension given by Myers and Swiatecki. Some numerical results are shown by using an appropriate nuclear matter equation of state
Thomas-Fermi model of warm nuclei
International Nuclear Information System (INIS)
Buchler, J.R.; Epstein, R.I.
1980-01-01
The average nuclear level density of spherical nuclei is computed with a finite temperature Thomas-Fermi model. More than 80% of the low energy nuclear excitations can be accounted for in terms of this statistical model. The relevance for stellar collapse is discussed
Viscosity: From air to hot nuclei
Indian Academy of Sciences (India)
November 2014 physics pp. 683–693. Viscosity: From air to hot nuclei. NGUYEN DINH DANG1,2. 1RIKEN Nishina Center for Accelerator-Based Science, RIKEN 2-1 Hirosawa, Wako City,. 351-0198 Saitama, Japan. 2Institute for Nuclear Science and Technique, 179 Hoang Quoc Viet, Nghia Do,. Cau Giay Hanoi, Vietnam.
Test of pseudospin symmetry in deformed nuclei
International Nuclear Information System (INIS)
Ginocchio, J.N.; Leviatan, A.; Meng, J.; Zhou Shangui
2004-01-01
Pseudospin symmetry is a relativistic symmetry of the Dirac Hamiltonian with scalar and vector mean fields equal and opposite in sign. This symmetry imposes constraints on the Dirac eigenfunctions. We examine extensively the Dirac eigenfunctions of realistic relativistic mean field calculations of deformed nuclei to determine if these eigenfunctions satisfy these pseudospin symmetry constraints
Growth and Interaction of Colloid Nuclei
Lam, Michael-Angelo; Khusid, Boris; Meyer, William; Kondic, Lou
2017-11-01
We study evolution of colloid systems under zero-gravity conditions. In particular, we focus on the regime where there is a coexistence between a liquid and a solid state. Under zero gravity, the dominating process in the bulk of the fluid phase and the solid phase is diffusion. At the moving solid/liquid interface, osmotic pressure is balanced by surface tension, as well as balancing fluxes (conservation of mass) with the kinematics of nuclei growth (Wilson-Frenkel law). Due to the highly nonlinear boundary condition at the moving boundary, care has to be taken when performing numerical simulations. In this work, we present a nonlinear model for colloid nuclei growth. Numerical simulations using a finite volume method are compared with asymptotic analysis of the governing equation and experimental results for nuclei growth. Novel component in our numerical simulations is the inclusion of nonlinear (collective) diffusion terms that depend on the chemical potentials of the colloid in the solid and fluid phase. The results include growth and dissolution of a single colloidal nucleus, as well as evolution of multiple interacting nuclei. Supported by NASA Grant No. NNX16AQ79G.
Electronuclear sum rules for the lightest nuclei
International Nuclear Information System (INIS)
Efros, V.D.
1992-01-01
It is shown that the model-independent longitudinal electronuclear sum rules for nuclei with A = 3 and A = 4 have an accuracy on the order of a percent in the traditional single-nucleon approximation with free nucleons for the nuclear charge-density operator. This makes it possible to test this approximation by using these sum rules. The longitudinal sum rules for A = 3 and A = 4 are calculated using the wave functions of these nuclei corresponding to a large set of realistic NN interactions. The values of the model-independent sum rules lie in the range of values calculated by this method. Model-independent expressions are obtained for the transverse sum rules for nuclei with A = 3 and A = 4. These sum rules are calculated using a large set of realistic wave functions of these nuclei. The contribution of the convection current and the changes in the results for different versions of realistic NN forces are given. 29 refs., 4 tabs
Radiative muon capture on nuclei and protons
International Nuclear Information System (INIS)
Azuelos, G.; Gorringe, T.P.; Henderson, R.; Macdonald, J.A.; Poutissou, J.M.; Azuelos, G.; Depommier, P.; Poutissou, R.; Ahmad, S.; Burnham, A.; Hasinoff, M.D.; Larabee, A.J.; Waltham, C.E.; Wright, D.H.; Armstrong, D.S.; Blecher, M.; Serna-Angel, A.; Bertl, W.; Chen, C.Q.; Zhang, N.S.; McDonald, S.C.; Taylor, G.N.; Robertson, B.C.
1990-01-01
A brief review is made of the study of gp, the induced pseudoscalar coupling constant, in radiative muon capture on light nuclei, and of motivations for a measurement on hydrogen, with particular emphasis on recent and ongoing experiments at TRIUMF [fr
Superheavy nuclei – cold synthesis and structure
Indian Academy of Sciences (India)
120 and Ж = 172 or 184, for superheavy nuclei. This result is discussed in ... 1980 [7] on the basis of the QMFT, once again prior to its observation in 1984. Thus, cold ... On the other hand, based on a rather complete deformed relativistic mean field (DRMF) calculation, using the NL1 parameter set, we [16] predicted. = 120.
Efimov effect in 2-neutron halo nuclei
Indian Academy of Sciences (India)
This paper presents an overview of our theoretical investigations in search of Efimov states in light 2-neutron halo nuclei. The calculations have been carried out within a three-body formalism, assuming a compact core and two valence neutrons forming the halo. The calculations provide strong evidence for the occurrence ...
Energy Technology Data Exchange (ETDEWEB)
Gastebois, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1968-06-01
The experimental results obtained in the study of the (d,p) reactions, at E{sub d} = 12 MeV, on the three even-even deformed nuclei {sup 170}Yb, {sup 172}Yb and {sup 174}Yb have been analysed in terms of DWBA calculations. The spectroscopic information relative to the odd final nuclei have been compared with the predictions of the collective model and of the Nilsson's model. The effect of various parameters used in the DWBA analysis (form factors, optical wave functions) has been carefully studied. The observed differences between the three final nuclei are qualitatively reproduced in the experimental study of resonances, seen in excitation functions of elastically and inelastically scattered protons on the same target nuclei, and corresponding to analogue states in the three nuclei {sup 171}Lu, {sup 173}Lu and {sup 175}Lu. (author) [French] Les resultats experimentaux de l'etude des reactions (d.p) a E{sub d} = 12 MeV, sur les noyaux deformes pairs-pairs {sup 170}Yb, {sup 172}Yb et {sup 174}Yb ont ete interpretes dans le cadre de l'approximation de Born des ondes deformees. Les informations spectroscopiques relatives aux noyaux impairs finals ont ete comparees aux predictions du modele collectif et du modele de Nilsson, apres avoir examine avec soin l'influence des differents parametres (facteurs de forme, fonctions d'onde 'optiques') utilises lors de l'analyse. Les differences observees entre les trois noyaux finals sont qualitativement reproduites par les resultats experimentaux de l'etude de resonances dans les fonctions d'excitation de diffusion elastique et inelastique de protons sur les memes noyaux-cibles, lors de la recherche d'etats analogues dans les noyaux {sup 171}Lu, {sup 173}Lu et {sup 175}Lu. (auteur)
Pollack, J. B.; Cuzzi, J. N.
1980-01-01
A semiempirical theory is developed which is based on simple physical principles and comparisons with laboratory measurements. The ultimate utility of this approach rests on its ability to successfully reproduce the observed single-scattering phase function for a wide variety of particle shapes, sizes and refractive indices. This approximate theory is developed for evaluating the interaction of randomly oriented, nonspherical particles with the total intensity component of electromagnetic radiation. Mie theory is used when the particle size parameter x (ratio of particle circumference to wavelength) is less than some upper bound x sub zero (about 5). For x greater than x sub zero, the interaction is divided into three components: diffraction, external reflection and transmission. The application of the theory is illustrated by considering the influence of the shape of tropospheric aerosols on their contribution to the earth's global albedo.
Nuclear moments of nuclei near sphericity
International Nuclear Information System (INIS)
El Hajjaji, O.
1987-05-01
Magnetic and electric hyperfine interactions are studied by means of low temperature nuclear orientation. The magnetic moment of the 149 Gd isotope and that of 151 Gd are determined. The values follow the same trend as literature values of neighbouring nuclei. The calculated moments of the 7/2 - states using the Mottelson-Nilsson model without configuration mixing are nearly independent of deformation. Thus we assign the decrease of the magnetic moment versus neutron number to many particle coupling in the f shell. The Moessbauer effect detection of nuclear orientation is discussed. Two series of experiences are performed with different finalities. In the first one we determined the electric quadrupole moments of 125m Te and 129 Te. The quadrupole moments confirm the nearly spherical shape of these nuclei. In the second series we describe the Moessbauer effect of the radiation emitted by the daigleter nucleus of 125 I, implanted in two semiconductor matrices, locally oriented at low temperature by the electric field gradient of impurity-vacancy coupling. Despite the difficulty of the cooling down of Te nuclei to lattice temperature, we have shown the existence of the electric field gradient of implanted I into Si and α-Sn and determined their signs. The level mixing resonance is applied on oriented nuclei technique to determine the weak prolate deformation of silver nuclei. Studying the Δm = 3 resonance of 107 Ag m , we etablished the quadrupole moment of this state, which is in good agreement with the theoretical estimations of Moeller and Nix [fr
Ice Nuclei Production in Volcanic Clouds
Few, A. A.
2012-12-01
The paper [Durant et al., 2008] includes a review of research on ice nucleation in explosive volcanic clouds in addition to reporting their own research on laboratory measurements focused on single-particle ice nucleation. Their research as well as the research they reviewed were concerned with the freezing of supercooled water drops (250 to 260 K) by volcanic ash particles acting as ice freezing nuclei. Among their conclusions are: Fine volcanic ash particles are very efficient ice freezing nuclei. Volcanic clouds likely contain fine ash concentrations 104 to 105 times greater than found in meteorological clouds. This overabundance of ice nuclei will produce a cloud with many small ice crystals that will not grow larger as they do in meteorological clouds because the cloud water content is widely distributed among the numerous small ice crystals. The small ice crystals have a small fall velocity, thus volcanic clouds are very stable. The small ice crystals are easily lofted into the stratosphere transporting water and adsorbed trace gasses. In this paper we examine the mechanism for the production of the small ice nuclei and develop a simple model for calculating the size of the ice nuclei based upon the distribution of magma around imbedded bubbles. We also have acquired a volcanic bomb that exhibits bubble remnants on its entire surface. The naturally occurring fragments from the volcanic bomb reveal a size distribution consistent with that predicted by the simple model. Durant, A. J., R. A. Shaw, W. I. Rose, Y. Mi, and G. G. J. Ernst (2008), Ice nucleation and overseeding of ice in volcanic clouds, J. Geophys. Res., 113, D09206, doi:10.1029/2007JD009064.
Nuclear Shell Structure and Beta Decay I. Odd A Nuclei II. Even A Nuclei
Mayer, M.G.; Moszkowski, S.A.; Nordheim, L.W.
1951-05-01
In Part I a systematics is given of all transitions for odd A nuclei for which sufficiently reliable data are available. The allowed or forbidden characters of the transitions are correlated with the positions of the initial and final odd nucleon groups in the nuclear shell scheme. The nuclear shells show definite characteristics with respect to parity of the ground states. The latter is the same as the one obtained from known spins and magnetic moments in a one-particle interpretation. In Part II a systematics of the beta transitions of even-A nuclei is given. An interpretation of the character of the transitions in terms of nuclear shell structure is achieved on the hypothesis that the odd nucleon groups have the same structure as in odd-A nuclei, together with a simple coupling rule between the neutron and proton groups in odd-odd nuclei.
Stamnes, S.; Ou, S. C.; Lin, Z.; Takano, Y.; Tsay, S. C.; Liou, K.N.; Stamnes, K.
2016-01-01
The reflection and transmission of polarized light for a cirrus cloud consisting of randomly oriented hexagonal columns were calculated by two very different vector radiative transfer models. The forward peak of the phase function for the ensemble-averaged ice crystals has a value of order 6 x 10(exp 3) so a truncation procedure was used to help produce numerically efficient yet accurate results. One of these models, the Vectorized Line-by-Line Equivalent model (VLBLE), is based on the doubling- adding principle, while the other is based on a vector discrete ordinates method (VDISORT). A comparison shows that the two models provide very close although not entirely identical results, which can be explained by differences in treatment of single scattering and the representation of the scattering phase matrix. The relative differences in the reflected I and Q Stokes parameters are within 0.5 for I and within 1.5 for Q for all viewing angles. In 1971 Hansen showed that for scattering by spherical particles the 3 x 3 approximation is sufficient to produce accurate results for the reflected radiance I and the degree of polarization (DOP), and he conjectured that these results would hold also for non-spherical particles. Simulations were conducted to test Hansen's conjecture for the cirrus cloud particles considered in this study. It was found that the 3 x 3 approximation also gives accurate results for the transmitted light, and for Q and U in addition to I and DOP. For these non-spherical ice particles the 3 x 3 approximation leads to an absolute error 2 x 10(exp -6) for the reflected and transmitted I, Q and U Stokes parameters. Hence, it appears to be an excellent approximation, which significantly reduces the computational complexity and burden required for multiple scattering calculations.
Generator coordinate method and superdeformation in A=190 nuclei
Energy Technology Data Exchange (ETDEWEB)
Dancer, H.; Perres, S.; Bonche, P.; Flocard, H.; Heenen, P.-H.; Meyer, J. E-mail: jmeyer@ipnl.in2p3.fr; Meyer, M
1999-07-26
The Generator Coordinate Method with particle number projection using a set of Hartree-Fock plus BCS states is applied to the superdeformed even-even Hg and Pb isotopes. The q{sub 30} and q{sub 32} octupole vibrations are investigated in even-even Hg and Pb isotopes. These one-dimensional calculations predict that the collective octupole K{sup {pi}}=0{sup -} excitations are the lowest mode in energy. The electric monopole E0 decay out of superdeformed states is also compared to the electric quadrupole E2 transition rates.
Probing the density tail of radioactive nuclei with antiprotons
Obertelli, Alexandre; Uesaka, Tomohiro; Corsi, Anna; Pollacco, Emmanuel; Flavigny, Freddy
2017-01-01
We propose an experiment to determine the proton and neutron content of the radial density tail in short-lived nuclei. The objectives are to (i) to evidence new proton and neutron halos, (ii) to understand the development of neutron skins in medium-mass nuclei, (iii) to provide a new observable that characterises the density tail of short-lived nuclei.
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.
Electron interactions with nuclei: Progress report
International Nuclear Information System (INIS)
McCarthy, J.S.
1987-08-01
High energy is being conducted at the Stanford Linear Accelerator Center. This includes inclusive electron scattering, electroexcitation of the delta in nuclei, longitudinal and transverse response in the quasi-elastic region, the q 2 dependence of 4 He(e,e'p), deep inelastic scattering from nuclei, transverse and longitudinal response in the resonance region, nuclear physics at PEP and 1.6 GeV spectrometer properties. Additional high energy research on electron scattering on 3 H and 3 He and the nuclear structure of 205 Tl and 206 Pb are being conducted at MIT-Bates. Other activities are being carried out at Saclay and research and development for Monte Carlo studies of Hall A spectrometers for CEBAF is being conducted
Monopole Strength Function of Deformed Superfluid Nuclei
Energy Technology Data Exchange (ETDEWEB)
Stoitsov, M. V. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Kortelainen, E. M. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Nakatsukasa, T. [RIKEN, Japan; Losa, C. [International School for Advanced Studies (SISSA), Trieste, Italy; Nazarewicz, Witold [ORNL
2011-01-01
We present an efficient method for calculating strength functions using the finite amplitude method (FAM) for deformed superfluid heavy nuclei within the framework of the nuclear density functional theory. We demonstrate that FAM reproduces strength functions obtained with the fully self-consistent quasi-particle random-phase approximation (QRPA) at a fraction of computational cost. As a demonstration, we compute the isoscalar and isovector monopole strength for strongly deformed configurations in ^{240}Pu by considering huge quasi-particle QRPA spaces. Our approach to FAM, based on Broyden's iterative procedure, opens the possibility for large-scale calculations of strength distributions in well-bound and weakly bound nuclei across the nuclear landscape.
Tensor coupling and pseudospin symmetry in nuclei
International Nuclear Information System (INIS)
Alberto, P.; Castro, A.S. de; Lisboa, R.; Malheiro, M.
2005-01-01
In this work we study the contribution of the isoscalar tensor coupling to the realization of pseudospin symmetry in nuclei. Using realistic values for the tensor coupling strength, we show that this coupling reduces noticeably the pseudospin splittings, especially for single-particle levels near the Fermi surface. By using an energy decomposition of the pseudospin energy splittings, we show that the changes in these splittings come mainly through the changes induced in the lower radial wave function for the low-lying pseudospin partners and through changes in the expectation value of the pseudospin-orbit coupling term for surface partners. This allows us to confirm the conclusion already reached in previous studies, namely that the pseudospin symmetry in nuclei is of a dynamical nature
Electron interactions with nuclei. Progress report
International Nuclear Information System (INIS)
1986-07-01
Research includes work at SLAC, Bates, and Saclay research facilities. The high energy program at SLAC concerns inclusive electron scattering from nuclei, electroexcitation of the delta in nuclei, and the design of an electron detection system for the SLAC 1.6 GeV/c magnetic spectrometer. The high energy program at Bates includes quasielastic electron scattering from 1 H, 2 H, 3 He, and 4 He, and electron scattering from 3 H and 3 He. Nuclear structure studies are based on high resolution inelastic electron scattering and include electron scattering from 208 Pb and mercury isotopes, charge densities from low lying states in 86 Sr, and magnetization densities of 205 Tl and 207 Pb. (DWL) 72 refs., 29 figs., 1 tab
SP (4,R) symmetry in light nuclei
International Nuclear Information System (INIS)
Peterson, D.R.
1979-01-01
A classification of nuclear states according to the noncompact sympletic Lie algebras sp(2n,R), n = 1, 2, 3, is investigated. Such a classification has recently been shown to be physically meaningful. This classification scheme is the appropriate generalization fo Elliott's SU 3 model of rotational states in deformed light nuclei to include core excitations. A restricted classification according to the Lie algebra, sp(4,R), is motivated. Truncation of the model space to a single sp(4,R) irreducible representation allows the inclusion of states possessing very high excitation energy. An sp(4,R) model study is performed on S = T = 0 positive-parity rotational bands in the deformed light nuclei 16 O and 24 Mg. States are included in the model space that possess up to 10h ω in excitation energy. Results for the B(E2) transition rates compare favorable with experiment, without resort to effective charges
Nuclear structure investigations on spherical nuclei
International Nuclear Information System (INIS)
Heisenberg, J.; Calarco, J.; Dawson, J.; Hersman, F.W.
1989-09-01
This report discusses the following topics: electron scattering studies on spherical nuclei; electron scattering from collective states in deformed nuclei; proton and pion scattering studies; 12 C(e,e'p) and 16 O(e,e'p); 12 C(e,e'α) and 16 O(e,e'α); studies at high q at Bates; measurements with rvec e at Bates; 12 C(γ,p); future directions in giant resonance studies; proton knockout from 16 O; quasielastic studies at Bates; triple coincidence studies of nuclear correlations; contributions to (e,e'2p) at KIKHEF; contributions to instrumentation at CEBAF; instrumentation development at UNH; the Bates large acceptance spectrometer toroid; shell model and core polarization calculations; and the relativistic nuclear model
Nuclei at HERA and heavy ion physics
International Nuclear Information System (INIS)
Gavin, S.; Strikman, M.
1995-01-01
Copies of 16 viewgraph sets from a workshop held at Brookhaven National Laboratory, 17-18 November, 1995. Titles of talks: HERA: The Present; HERA: Potential with Nuclei; Review of Hadron-Lepton Nucleus Data; Fermilab E665: results in muon scattering; Interactions of Quarks and Gluons with Nuclear Matter; Rescattering in Nuclear Targets for Photoproduction and DIS; Structure Functions and Nuclear Effect at PHENIX; Probing Spin-Averaged and Spin-Dependent Parton Distributions Using the Solenoidal Tracker at RHIC (STAR); Jet Quenching in eA, pA, AA; Nuclear Gluon Shadowing via Continuum Lepton Pairs; What can we learn from HERA with a colliding heavy ion beam? The limiting curve of leading particles at infinite A; Coherent Production of Vector Mesons off Light Nuclei in DIS; A Model of High Parton Densities in PQCD; Gluon Production for Weizaecker-Williams Field in Nucleus-Nucleus Collisions; Summary Talk
Disappearance of collective motion in hot nuclei
Energy Technology Data Exchange (ETDEWEB)
Santonocito, D.; Piattelli, P.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Hongmei, F.; Maiolino, C.; Migneco, E.; Sapienza, P. [INFN-LNS, Laboratori Nazionali del Sud, Catania (Italy); Blumenfeld, Y.; Delaunay, F.; Frascaria, N.; Lima, V.; Scarpaci, J. [Institut de Physique Nucleaire, IN2P3-CNRS, 91 - Orsay (France); Migneco, E. [Catania Univ., Dipartimento di Fisica (Italy)
2003-07-01
The evolution of the GDR {gamma} yield for excitation energies between 160 and 300 MeV has been investigated in nuclei of mass A {approx} 126 through the reactions {sup 116}Sn + {sup 12}C and {sup 24}Mg at 17 and 23 A*MeV. Gamma-rays were detected with MEDEA array in coincidence with residues detected in MACISTE. The evolution of the GDR parameters has been investigated as a function of the linear momentum transferred to the fused system. This procedure allowed us to select hot nuclei produced in incomplete fusion reactions with different excitation energies. The analysis of the {gamma} spectra and their comparison with CASCADE calculations is presented. Results suggest a saturation of the GDR yield between 200 and 300 MeV excitation energy. (authors)
Antiproton Induced Fission and Fragmentation of Nuclei
2002-01-01
The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...
EMC effect and multiquark bags in nuclei
International Nuclear Information System (INIS)
Kondratyuk, L.; Shmatikov, M.
1984-01-01
Assuming existence of 9q- and 12q bags in niclei the form factors of light nuclei at large momentum transfers and structure functions of deep inelastic scattering of leptons on nuclei are described. It is shown that the existing experimental data can be described in a unified way provided the momentum distribution of quarks in multiquark bags at k 0 has the exponential form PSIsub(q)sup(2)(k) approximately esup(-k/k 0 ) with the parameter k 0 approximately 50-60 MeV. Theoretical results agree well the EMC experimental data on the ratio of the iron and deuteron structure functions with the 20% admixture of 12q-bags in the Fe nucleus
Light-Nuclei Spectra from Chiral Dynamics
Piarulli, M.; Baroni, A.; Girlanda, L.; Kievsky, A.; Lovato, A.; Lusk, Ewing; Marcucci, L. E.; Pieper, Steven C.; Schiavilla, R.; Viviani, M.; Wiringa, R. B.
2018-02-01
In recent years local chiral interactions have been derived and implemented in quantum Monte Carlo methods in order to test to what extent the chiral effective field theory framework impacts our knowledge of few- and many-body systems. In this Letter, we present Green's function Monte Carlo calculations of light nuclei based on the family of local two-body interactions presented by our group in a previous paper in conjunction with chiral three-body interactions fitted to bound- and scattering-state observables in the three-nucleon sector. These interactions include Δ intermediate states in their two-pion-exchange components. We obtain predictions for the energy levels and level ordering of nuclei in the mass range A =4 - 12 , accurate to ≤2 % of the binding energy, in very satisfactory agreement with experimental data.
The structure of nuclei far from stability
International Nuclear Information System (INIS)
Zganjar, E.F.
1993-01-01
Studies on nuclei near Z=82 contributed to the establishment of a new region of nuclear deformation and a new class of nuclear structure at closed shells. A important aspect of this work is the establishment of the connection between low-lying 0 + states in even endash even nuclei and the occurrence of shape coexistence in the odd-mass neighbors (E0 transitions in 185 Pt, shape coexistence in 184 Pt and 187 Au). A new type of picosecond lifetime measurement system capable of measuring the lifetime of states that decay only by internal conversion was developed and applied to the 186,188 Tl decay to determine the lifetime of the 0 2 + and 2 2 + deformed states in 186,188 Hg. A search for the population of superdeformed states in 192 Hg by the radioactive decay of 192 Tl was accomplished by using a prototype internal pair formation spectrometer
Decay and fission of the oriented nuclei
Kadmenskij, S G
2002-01-01
The fragment angular distributions for binary decay of oriented spherical and deformed nuclei with taking into account the correct transformational properties of wave functions under time inversion have been investigated. It has been shown that for description of fragment angular distributions the adiabatic approximation for collective rotational nuclear degrees of freedom is not correct. It has been demonstrated that this approximation is valid for description of spontaneous and induced low-energy nuclear fission. The dependence of partial fission widths on the orientation of the internal axes spins, projections of spins, and relative angular moments of fission fragments has been analyzed. It has been shown that the adiabatic approximation results in coherent interference of wave functions of fragments relative movement. This interference forms fragments the universal angular distributions of fission fragments for oriented nuclei. For these distributions the deviations from A. Bohr's formula have been invest...
Realistic microscopic level densities for spherical nuclei
International Nuclear Information System (INIS)
Cerf, N.
1994-01-01
Nuclear level densities play an important role in nuclear reactions such as the formation of the compound nucleus. We develop a microscopic calculation of the level density based on a combinatorial evaluation from a realistic single-particle level scheme. This calculation makes use of a fast Monte Carlo algorithm allowing us to consider large shell model spaces which could not be treated previously in combinatorial approaches. Since our model relies on a microscopic basis, it can be applied to exotic nuclei with more confidence than the commonly used semiphenomenological formuals. An exhaustive comparison of our predicted neutron s-wave resonance spacings with experimental data for a wide range of nuclei is presented
Deeply virtual Compton scattering off nuclei
Energy Technology Data Exchange (ETDEWEB)
Voutier, Eric
2009-01-01
Deeply virtual Compton scattering (DVCS) is the golden exclusive channel for the study of the partonic structure of hadrons, within the universal framework of generalized parton distributions (GPDs). This paper presents the aim and general ideas of the DVCS experimental program off nuclei at the Jefferson Laboratory. The benefits of the study of the coherent and incoherent channels to the understanding of the EMC (European Muon Collaboration) effect are discussed, along with the case of nuclear targets to access neutron GPDs.
AMS with light nuclei at small accelerators
Stan-Sion, C.; Enachescu, M.
2017-06-01
AMS applications with lighter nuclei are presented. It will be shown how Carbon-14, Boron-10, Beryllium-10, and Tritium-3 can be used to provide valuable information in forensic science, environmental physics, nuclear pollution, in material science and for diagnose of the plasma confinement in fusion reactors. Small accelerators are reliable, efficient and possess the highest ion beam transmissions that confer high precision in measurements.
Production and identification of very exotic nuclei
International Nuclear Information System (INIS)
Pougheon, F.
1986-01-01
New very exotic nuclei have been produced by fragmentation of the projectile at intermediate energy at GANIL. They have been identified through time of flight and ΔE-E measurements after a magnetic separation with the 0 0 LISE spectrometer. New neutron rich isotopes have been identified up to Z = 26 and evidence for the stability of the new series Tz = -5/2 has been shown. These results improve the knowledge of the neutron and proton drip lines
Fission of nuclei far from stability
International Nuclear Information System (INIS)
Schmidt, K.H.; Benlliure, J.; Junghans, A.R.
2000-11-01
The secondary-beam facility of GSI provided the technical equipment for a new kind of fission experiment. Fission properties of short-lived neutron-deficient nuclei have been investigated in inverse kinematics. The measured element distributions reveal new kinds of systematics on shell structure and even-odd effects and lead to an improved understanding of structure effects in nuclear fission. Prospects for further experimental studies are discussed. (orig.)
Electromagnetic interactions with nuclei and nucleons
International Nuclear Information System (INIS)
Thornton, S.T.; Sealock, R.M.
1990-01-01
This report discusses the following topics: general LEGS work; photodisintegration of the deuteron; progress towards other experiments; LEGS instrumentation; major LEGS software projects; NaI detector system; nucleon detector system; waveshifting fibers; EGN prototype detector for CEBAF; photon beam facility at CEBAF; delta electroproduction in nuclei; quasielastic scattering and excitation of the Delta by 4 He(e,e'); and quasielastic scattering at high Q 2
Order and chaos in atomic nuclei
International Nuclear Information System (INIS)
Rotter, I.
1991-01-01
The interplay between regular and chaotic motion in nuclei is investigated in the framework of an open quantum mechanical system. The effect of avoided resonance overlapping (trapping) leads to long-lived traps which correspond to the formation of quantum chaos. They are hidden by short-lived states which correspond to the formation of a new order with less degrees of freedom. The quantum chaos in the nuclear system may be investigated by means of rare decays. (author)
Some Aspects of Collective Properties of Nuclei
International Nuclear Information System (INIS)
Belyaev, S.T.
1963-01-01
Certain questions connected with the collective properties of nuclei will be considered in this paper. There are two different complementary approaches in the consideration of collective motions. One method - we shall call it the phenomenological one - consists of directly introducing collective degrees of freedom and the corresponding collective Hamiltonian, H coll , with some phenomenological parameters. The aim of such a theory is, first, to solve the Schrodinger equation with the Hamiltonian H coll , and secondly to calculate the parameters in Hcoil under certain assumptions or using certain models. The Davydov-Filippov model can serve as an example of such an approach to the investigation of collective properties of nuclei. There it is supposed that Hc0udescribes a non-axial rotator and the parameters of the Hamiltonian are then chosen so as to obtain the best fit to experimental data. The second possible method of investigating collective excitations of nuclei - let us call it the microscopic one - works right from the beginning with a many-body Hamiltonian H = H o + H int . Then such excitations in a system of nucleons, the nature of which is collective, are studied. In this method no additional collective degrees of freedom, and hence no additional phenomenological parameters, are introduced a priori. In principle, everything is determined by the nucleon-nucleon interaction H int . As a matter of fact, the interaction H int must practically be introduced phenomenologically, since it has not been possible to derive it from first principles so far. The actual difference is in the ''degree of phenomenologicality'', i.e . in the number of parameters introduced into the theory. One needs only one or two parameters, which in principle determine the various properties of all nuclei, to determine H int . whereas in the above-mentioned example of a non-axial rotator, two parameters are introduced for each nucleus (the value of the first 2 + level and the degree of
Shell effects and nucleosynthesis of heavy nuclei
International Nuclear Information System (INIS)
Farhan, A.R.; Sharma, M.M.
2005-01-01
The nuclear shell effects across the magic numbers N = 50, 82 and 126 near the r-process path are crucial to understanding the nucleosynthesis of heavy nuclei. Since nuclei near the r-process path are extremely neutron rich and are not accessible in the laboratory, the current understanding of the nuclear abundances is based much upon extrapolations of various mass formulae. In this talk, we will discuss as to how the shell effects evolve in going from the stability line to the r-process path and towards drip line in the heavy mass region. Within the framework of to the relativistic Hartree-Bogoliubov (RHB) theory with the vector self-coupling of omega meson, it will be shown that the shell effects across N = 82 show a significant decline in going from the r-process path to the drip line, whereas those at N = 126 remain resilient to the change in isospin in going from the r-process path to the neutron drip line. This behaviour of the microscopic RHB calculations is consistent with the recent r-process calculations suggesting that a shell quenching at N = 82 would be useful, however, a quenching is not necessary for reproducing r-process abundances near the peak at A ∼ 190. We will also show that due to an onset of deformation for nuclei above N = 126, an additional stability in some nuclei beyond the neutron drip line is provided. Consequently, this would contribute to r-process nuclear abundances in the third peak. A comparative analysis of shell effects with the microscopic RMF theory and with the macroscopic-microscopic mass formulae shows that the microscopic RMF theory possesses the potential of describing nuclear abundances in the peaks about A ∼ 130 and A ∼ 190. (author)
The Skyrmions and quarks in nuclei
International Nuclear Information System (INIS)
Rho, M.
1984-08-01
It is proposed that the quark-bag description and the Skyrmion description of baryons are related to each other by quantized parameters. Topology (through a chiral anomaly) plays an important role in bridging the fundamental theory of the strong interactions (QCD) to effective theories. Some consequences on the efforts to see quark degrees of freedom in nuclear matter are discussed. It is suggested that at low energies there will be no ''smoking gun'' evidences for quark presence in nuclei
Dynamical timescales in hot rotating nuclei
International Nuclear Information System (INIS)
Thoennessen, M.; Michigan State Univ., East Lansing, MI
1996-01-01
The effects of dissipation in fission of hot nuclei as well as in heavy-ion reactions are still not well understood and quite controversial. The deformation and/or temperature dependence of the dissipation coefficient as well as the influence of the curvatures of the potential energy surface will be discussed. Evidence for particle/γ-ray decay during compound nucleus formation in certain heavy-ion reactions will be compared to other reactions where no effects were observed. (orig.)
Chiral bags, skyrmions and quarks in nuclei
International Nuclear Information System (INIS)
Rho, M.
1984-09-01
Recent developments on an intriguing connection between the quark-bag description of the baryons (nucleons in particular) and the Skyrmion model are discussed in terms of the constraints coming from chiral anomalies. Topics treated are the leaking baryon charge, axial charge and energy density; the role of chiral anomalies; the role of Skyrme's quartic term and the connection to the meson degrees of freedom; and finally some qualitative implications in nuclei. The presentation is purposely descriptive and intuitive instead of mathematically precise
Decay of heavy and superheavy nuclei
Indian Academy of Sciences (India)
study on the feasibility of observing α decay chains from the isotopes of the superheavy nuclei. Z = 115 in the range 271 ≤ A ≤ 294 and the isotopes of Z = 117 in the range 270 ≤ A ≤ 301, within the Coulomb and .... For Ri we use semiempirical formula in terms of mass number Ai as [3]. Ri = 1.28A. 1/3 i. − 0.76 + 0.8A.
''Identical'' bands in normally-deformed nuclei
International Nuclear Information System (INIS)
Garrett, J.D.; Baktash, C.; Yu, C.H.
1990-01-01
Gamma-ray transitions energies in neighboring odd- and even-mass nuclei for normally-deformed nuclear configurations are analyzed in a manner similar to recent analyses for superdeformed states. The moment of inertia is shown to depend on pair correlations and the aligned angular momentum of the odd nucleon. The implications of this analysis for ''identical'' super-deformed bands are discussed. 26 refs., 9 figs
Soft radiative strength in warm nuclei
International Nuclear Information System (INIS)
Becker, J A; Bernstein, L A; Garrett, P E; Nelson, R O; Schiller, A; Voinov, A; Agvaanluvsan, U; Algin, E; Belgya, T; Chankova, R; Guttormsen, M; Mitchell, G E; Rekstad, J; Siem, S
2004-01-01
Unresolved transitions in the nuclear γ-ray cascade produced in the decay of excited nuclei are best described by statistical concepts: a continuous radiative strength function (RSF) and level density yield mean values of transition matrix elements. Data on the soft (E γ < 3-4 MeV) RSF for transitions between warm states (i.e. states several MeV above the yrast line) have, however, remained elusive
Double charge exchange of pions on nuclei
International Nuclear Information System (INIS)
Dzhibuti, R.I.; Kezerashvili, R.Y.
1985-01-01
An analysis is made of the results of experimental and theoretical studies during the last ten years of a unique process: double charge exchange of pions on nuclei. On the one hand, the commissioning of meson factories and the use of new and more accurate experimental methods have led to the accumulation of rich and reliable material for not only light but also medium and heavy nuclei. On the other hand, the development and application of new microscopic theoretical approaches have led to a deepening of our ideas about the mechanism of these exotic reactions at low, intermediate, and high energies. The currently existing methods of theoretical investigation and all possible reaction mechanisms are considered. Particular attention is devoted to double charge exchange of pions on the lightest nuclei, for the theoretical description of which it is possible to use the well-developed methods for investigating few-particle systems. The experimental investigations of double-isobar analog and nonanalog transitions in the reaction of double charge exchange are systematized
History of cluster structure in nuclei
International Nuclear Information System (INIS)
Brink, D M
2008-01-01
This contribution focuses on the history of clustering in nuclei. Elementary alpha models treat light 4-n nuclei as systems of alpha-particles obeying Bose Einstein statistics. These models neglect the internal structure of the alphas and effects of the Pauli principle between the nucleons in the alpha clusters are taken into account by introducing a short range repulsion between the clusters. The orthogonality condition model and excluded state model treat the alphas as elementary particles, but include effects of the Pauli principle in a more microscopic way. Wheeler's resonating group method is a fully microscopic theory for calculating properties of cluster systems. It makes simplifying assumptions about the internal structure of the clusters but takes the Pauli principle explicitly. Hartree-Fock theory can be used for a microscopic theory of nuclear structure but it is not suitable for light nuclei because there is no well defined mean field. Margenau's microscopic cluster model avoids this problem by using trial wave functions which are antisymmetrized products of parametrized single particle wave functions
Toward yrast spectroscopy in soft vibrational nuclei
International Nuclear Information System (INIS)
Marumori, Toshio; Kuriyama, Atsushi; Sakata, Fumihiko.
1979-10-01
In a formally parallel way with that exciting progress has been recently achieved in understanding the yrast spectra of the rotational nuclei in terms of the quasi-particle motion in the rotating frame, an attempt to understand the yrast spectra of the vibrational nuclei in terms of the quasi-particle motion is proposed. The essential idea is to introduce the quasi-particle motion in a generalized vibrating frame, which can be regarded as a rotating frame in the gauge space of ''physical'' phonons where the number of the physical phonons plays the role of the angular momentum. On the basis of a simple fundamental principle called as the ''invariance principle of the Schroedinger equation'', which leads us to the ''maximal decoupling'' between the physical phonon and the intrinsic modes, it is shown that the vibrational frame as well as the physical-phonon-number operator represented by the quasi-particles can be self-consistently determined. A new scope toward the yrast spectroscopy of the vibrational nuclei in terms of the quasi-particle motion is discussed. (author)
Gamow-Teller Transitions in hot nuclei
International Nuclear Information System (INIS)
Vdovin, A.I.; Dzhioev, A.; Ponomarev, V.; Wambach, J.
2007-01-01
A temperature dependence of collective nuclear excitations (giant resonances (GR) in particular) is a subject of theoretical and experimental investigations for many years. One of the reasons of this interest is that the GR properties at finite temperatures are quite important in understanding various astrophysical processes. For example, electron or neutrino capture on nuclei plays an essential role in the early presupernova collapse. In that context, it is important to know the dependence of the charge-exchange and/or magnetic resonance strength distribution from stellar media temperature. To study the problem, we apply the formalism based on the quasiparticle phonon model extended to finite temperature using the thermo field dynamics. Following the TFD prescriptions we have constructed a microscopic thermal Hamiltonian which describes collective vibrations in a hot nucleus. In this approach, the fragmentation of the giant vibrations at T≠0 is due to the coupling with thermal two-phonon configurations. The calculations are performed for selected nuclei from the Fe region. The Gamow-Teller strength distributions are calculated within the thermal RPA at different temperatures. Then they are used to study a temperature dependence of -decay rates for these nuclei in stellar media.
Flow cytometry of DNA in mouse sperm and testis nuclei
Energy Technology Data Exchange (ETDEWEB)
Meistrich, M.L. (Univ. of Texas, Houston); Lake, S.; Steinmetz, L.L.; Gledhill, B.L.
1978-01-01
Mutations that occur in spermatogenic cells may be expressed as changes in DNA content, but developmentally-dependent alteration of its staining properties complicates the quantitation of DNA in individual germ cells. These alterations have been studied with flow cytometric techniques. Nuclei from mouse testis cells and sperm were stained by the acriflavine--Feulgen method. The fluorescence intensity frequency distribution of nuclei of testis cells was characterized by 2 major and 5 minor peaks. Nuclei sorted from the various peaks with a fluorescence-activated cell sorter were identified microscopically. These data were confirmed by generation of peaks with nuclei prepared from cell suspensions enriched in specific cell types. One of the major peaks corresponded to round spermatid nuclei. The other major peak, located at 0.6 of the fluorescence intensity of the round nuclei, corresponded to elongated spermatid nuclei. Purified nuclei of epididymal and vas deferens spermatozoa displayed asymmetric fluorescence distributions. A minor peak at 0.8 the intensity of the round spermatid nuclei was tentatively assigned to elongating spermatids. 2 of the minor peaks, located at 1.7 and 2.0 times the fluorescence intensity of the round nuclei, corresponded to clumps of 2 haploid and diploid nuclei.
Electric monopole transitions from low energy excitations in nuclei
Wood, J L; De Coster, C; Heyde, Kris L G
1999-01-01
Electric monopole (E0) properties are studied across the entire nuclear mass surface. Besides an introductory discussion of various model results (shell model, geometric vibrational and rotational models, algebraic models), we point out that many of the largest E0 transition strengths, $\\rho^2$(E0), are associated with shape mixing. We discuss in detail the manifestation of E0 transitions and present extensive data for~: single-closed shell nuclei, vibrational nuclei, well-deformed nuclei, nuclei that exhibit sudden ground-state changes, and nuclei that exhibit shape coexistence and intruder states. We also give attention to light nuclei, odd-A nuclei, and illustrate a suggested relation between $\\rho^2$(E0) and isotopic shifts.
From heavy nuclei to super-heavy nuclei; Des noyaux lourds aux super-lourds
Energy Technology Data Exchange (ETDEWEB)
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)
International Nuclear Information System (INIS)
Geissel, H.
1997-03-01
Examinations of the production cross-sections and the kinematics permitted refinement of model concepts of the peripheral reactions in exotic nuclei at energies from 100 to 1000 A MeV. Due to the strong selectivity and resolution achieved it was possible to discover a large number of novel isotopes at the fragment separator FRS, despite the relatively low projectile beam intensities of the SIS. The two twice magic nuclei found, Ni 78 and Sn 100, are particularly interesting, as they could not be measured so far with other experimental systems. Fission of relativistic uranium ions proved to be a particularly successful process yielding many medium-heavy, neutron-rich nuclei. Insight into the structure of light neutron halos could be improved. The superlarge spatial dimensions of the nuclear halos is discussed. (orig./CB) [de
Higaki, Shogo; Kurihara, Yuichi; Yoshida, Hiroko; Takahashi, Yoshio; Shinohara, Naohide
2017-10-01
Non-spherical heterogeneous radiocesium-bearing particles were found on masks worn during cleaning work in residences near the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), from which residents had evacuated. Three slightly larger (6.6-12 μm) non-spherical radiocesium-bearing particles were found in a residence in Futaba Town, a straight distance of 2.11 km west-northwest from the FDNPP. These were collected on October 25, 2016, 5 years and 7 months after the Fukushima Dai-ichi nuclear disaster and were presumed to originate from the Plant's Unit 2 based on the measured radioactivity ratio of 134 Cs/ 137 Cs. The main elemental composition was similar to particles already reported in other studies. However, this is the first time that such particles had a clearly heterogeneous distribution. Copyright © 2017 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Lazarev, Yu.A.
1986-01-01
An analytically solvable model is used to study the potential barrier penetrability in the case when the gap parameter Δ is treated as a dynamical variable governed by the least action principle. It is found that, as compared to the standard (BCS) approach, the dynamical treatment of pairing results in a considerably weakened dependence of the fission barrier penetrability on the intensity of pairing correlations in the initial state (Δ 0 ), on the barrier height, and on the energy of the initial state. On this basis, a more adequate explanation is proposed for typical order-of-magnitude values of the empirical hidrance factors for groun-state spontaneous fission of odd nuclei. It is also shown that a large enhancement of superfluidity in tunneling - the inherent effect of the dynamical treatment of pairing - strongly facilitates deeply subbarier fusion of complex nuclei. Finally, an analysis is given for the probability of spontaneous fission from K-isomeric quasiparticle (q-p) states in even-even heavy nuclei. The relative change of the partial spontaneous fission half-life in going from the ground-state to a high-spin q-p isomeric state, T* sf /T sf , is found to be strongly dependent on whether or not there takes place the dynamically induced enhancement of superfluidity in tunneling. Measurements of T* sf /T sf provide thus a unique possibility of verifying theoretical predictions about the strong, inverse-square Δ dependence of the effective inertia associated with large-scale subbarrier rearrangements of nuclei
The dynamics of the nuclei-nuclei interactions at very high energies
International Nuclear Information System (INIS)
Blaizot, J.P.
1988-01-01
The lectures on the dynamics of nuclei-nuclei interactions at very high energies, presented in the Summer School on Nuclear Physics and Particle Physics (1988), are shown. The equation of state of the hadronic matter is analyzed, by means of simple models, and some orders of magnitude can be asserted. The main characteristics of the high energy hadronic interactions are recalled. The basis of the dynamics of the relativistic fluids are given. Applications of this dynamics in the description of the space-time evolution of a plasma, generated by heavy ions collision, are carried out [fr
Nuclei at extreme conditions. A relativistic study
Energy Technology Data Exchange (ETDEWEB)
Afanasjev, Anatoli [Mississippi State Univ., Mississippi State, MS (United States)
2014-11-14
The major goals of the current project were further development of covariant density functional theory (CDFT), better understanding of its features, its application to different nuclear structure and nuclear astrophysics phenomena and training of graduate and undergraduate students. The investigations have proceeded in a number of directions which are discussed in detail in the part “Accomplishments” of this report. We have studied the role of isovector and isoscalar proton-neutron pairings in rotating nuclei; based on available experimental data it was concluded that there are no evidences for the existence of isoscalar proton-neutron pairing. Generalized theoretical approach has been developed for pycnonuclear reaction rates in the crust of neutron stars and interior of white dwarfs. Using this approach, extensive database for considerable number of pycnonuclear reactions involving stable and neutron-rich light nuclei has been created; it can be used in future for the study of various nuclear burning phenomena in different environments. Time-odd mean fields and their manifestations in terminating states, non-rotating and rotating nuclei have been studied in the framework of covariant density functional theory. Contrary to non-relativistic density functional theories these fields, which are important for a proper description of nuclear systems with broken time-reversal symmetry, are uniquely defined in the CDFT framework. Hyperdeformed nuclear shapes (with semi-axis ratio 2.5:1 and larger) have been studied in the Z = 40-58 part of nuclear chart. We strongly believe that such shapes could be studied experimentally in the future with full scale GRETA detector.
Signatures for quark clustering in nuclei
Energy Technology Data Exchange (ETDEWEB)
Carlson, C.E. [College of William and Mary, Williamsburg, VA (United States); Lassila, K.E. [Iowa State Univ., Ames, IA (United States)
1994-04-01
As a signature for the presence of quark clusters in nuclei, the authors suggest studying backward protons produced by electron scattering off deuterons and suggest a ratio that cancels out much of the detailed properties of deuterons or 6-quark clusters. The test may be viewed as a test that the short range part of the deuteron is still a 2-nucleon system. They make estimates to show how it fails in characteristic and significant ways if the two nucleons at short range coalesce into a kneaded 6-quark cluster.
The Structure of Nuclei Far from Stability
Energy Technology Data Exchange (ETDEWEB)
Zganjar, E.F.
1999-02-25
From among a number of important nuclear structure results that have emerged from our research program during the past few years, two stand out as being of extra significance. These are: (a) the identification of a diabatic coexisting structure in {sup 187}Au which arises solely from differences in proton occupation of adjacent oscillator shells, and (b) the realization of a method for estimating EO strength in nuclei and the resulting prediction that the de-excitation of superdeformed bands may proceed, in some cases, by strong EO transitions.
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
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)
Cluster and alpha decay of superheavy nuclei
Poenaru, D. N.; Stöcker, H.; Gherghescu, R. A.
2018-02-01
We investigated cluster radioactivity and alpha decay of some superheavy nuclei with atomic numbers Z = 119, 120 , which may be produced in the future. Two models are used to calculate the half-lives against cluster radioactivity: ASAF (Analytical Super-Asymmetric Fission) and UNIV (Universal Formula). For α decay half-lives we are based on four models: ASAF, UNIV, semFIS (semi-empirical formula based on Fission Theory) and AKRA (first author Akrawy). The Q -values are calculated using the theoretical model of atomic masses WS10, which sometimes is called W4.
Solitonic fullerene structures in light atomic nuclei.
Battye, R A; Sutcliffe, P M
2001-04-30
The Skyrme model is a classical field theory which has topological soliton solutions. These solitons are candidates for describing nuclei, with an identification between the numbers of solitons and nucleons. We have computed numerically, using two different minimization algorithms, minimum energy configurations for up to 22 solitons. We find, remarkably, that the solutions for seven or more solitons have nucleon density isosurfaces in the form of polyhedra made of hexagons and pentagons. Precisely these structures arise, though at the much larger molecular scale, in the chemistry of carbon shells, where they are known as fullerenes.
Signatures for quark clustering in nuclei
International Nuclear Information System (INIS)
Carlson, C.E.; Lassila, K.E.
1994-01-01
As a signature for the presence of quark clusters in nuclei, the authors suggest studying backward protons produced by electron scattering off deuterons and suggest a ratio that cancels out much of the detailed properties of deuterons or 6-quark clusters. The test may be viewed as a test that the short range part of the deuteron is still a 2-nucleon system. They make estimates to show how it fails in characteristic and significant ways if the two nucleons at short range coalesce into a kneaded 6-quark cluster
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
Nuclear Data on Unstable Nuclei for Astrophysics
International Nuclear Information System (INIS)
Smith, Michael Scott; Meyer, Richard A; Lingerfelt, Eric; Scott, J.P.; Hix, William Raphael; Ma, Zhanwen; Bardayan, Daniel W.; Blackmon, Jeff C.; Guidry, Mike W.; KOZUB, RAYMOND L.; Chae, Kyung YuK.
2004-01-01
Recent measurements with radioactive beams at ORNL's Holifield Radioactive Ion Beam Facility (HRIBF) have prompted the evaluation of a number of reactions involving unstable nuclei needed for stellar explosion studies. We discuss these evaluations, as well as the development of a new computational infrastructure to enable the rapid incorporation of the latest nuclear physics results in astrophysics models. This infrastructure includes programs that simplify the generation of reaction rates, manage rate databases, and visualize reaction rates, all hosted at a new website http://www.nucastrodata.org
Rotating bubble and toroidal nuclei and fragmentation
International Nuclear Information System (INIS)
Royer, G.; Haddad, F.; Jouault, B.
1995-01-01
The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy-ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. The potential barriers standing in these exotic deformation paths are compared with the three dimensional and plane fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localised below the plane fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension. (author)
Sub-Coulomb fusion with halo nuclei
International Nuclear Information System (INIS)
Fekou-Youmbi, V.; Sida, J.L.; Alamanos, N.; Auger, F.; Bazin, D.; Borcea, C.; Cabot, C.; Cunsolo, A.; Foti, A.; Gillibert, A.; Lepine, A.; Lewitowicz, M.; Liguori-Neto, R.; Mittig, W.; Pollacco, E.; Roussel-Chomaz, P.; Volant, C.; Yong Feng, Y.
1995-01-01
The nuclear structure of halo nuclei may have strong influence on the fusion cross section at sub-barrier energies. The actual theoretical debate is briefly reviewed and sub-barrier fusion calculations for the system 11 Be+ 238 U are presented. An experimental program on sub-barrier fusion for the systems 7,9,10,11 Be+ 238 U is underway at GANIL. First results with 9 Be and 11 Be beams were obtained using the F.U.S.ION detector. Relative fission cross sections are presented. ((orig.))
Inclusive charge longitudinal response in finite nuclei
International Nuclear Information System (INIS)
Alberico, W.M.; Molinari, A.; Czerski, P.; Czerski, P.; Ericson, M.
1986-03-01
The experimental dynamic and static longitudinal structure factors of 12 C, 40 Ca and 56 Fe are investigated with a semiclassical RPA theory. The parameters entering into the nuclear mean field (including the nucleon effective mass) and in the isoscalar and isovector particle-hole forces are set by best fitting procedures. Quite reasonable values of these quantities allow a satisfactory account of the experimental data over a wide range of momentum transfers in all the three nuclei. However, to achieve this result, the proton root mean square radius has to be increased over the conventional value of about 13% in 12 C and 22% in 40 Ca and 56 Fe
Light unstable nuclei in the continuum
International Nuclear Information System (INIS)
Kato, Kiyoshi
2000-01-01
It is discussed that the complex scaling method is one of the most available frameworks to solve many body resonances. As the recent developments of the complex scaling method, we present several ways to analyse the properties of resonant states; the matrix elements associated with resonant states, the extended completeness relation and partial widths of resonances. We also show the discussions on the binding mechanism and excited resonant structure of the Borromean systems 4 He+n+n and 9 Li+n+n. It is shown that the pairing correlation between valence neutrons and among core neutrons plays an important role in neutron-rich nuclei. (author)
Lectures on geometrical properties of nuclei
International Nuclear Information System (INIS)
Myers, W.D.
1975-11-01
Material concerning the geometrical properties of nuclei is drawn from a number of different sources. The leptodermous nature of nuclear density distributions and potential wells is used to draw together the various geometrical properties of these systems and to provide a unified means for their description. Extensive use is made of expansions of radial properties in terms of the surface diffuseness. A strong case is made for the use of convolution as a geometrical ansatz for generating diffuse surface distributions because of the number of simplifications that arise which are of practical importance. 7 figures
Modeling a neutron rich nuclei source
International Nuclear Information System (INIS)
Mirea, M.; Bajeat, O.; Clapier, F.; Ibrahim, F.; Mueller, A.C.; Pauwels, N.; Proust, J.; Mirea, M.
2000-01-01
The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (authors)
Giant dipole resonance in hot nuclei
International Nuclear Information System (INIS)
Mau, N.V.
1993-01-01
Giant resonances built on an excited state of the nucleus at a finite temperature T are studied. The following questions are investigated: how long such collective effects occur in a nucleus when T increases. How the properties of the giant resonances vary when the temperature increases. How the study of giant resonances in hot nuclei can give information on the structure of the nucleus in a highly excited state. The special case of the giant dipole resonance is studied. Some of the experimental results are reviewed and in their theoretical interpretation is discussed. (K.A.). 56 refs., 20 figs., 4 tabs
Electromagnetic properties of nuclei at high spins
International Nuclear Information System (INIS)
Leander, G.A.
1986-01-01
A photon emitted by an excited state is likely to carry away, at most, 1 or 2 h-bar of angular momentum. Therefore, a profusion of photons is needed to deexcite the rapidly rotating states of nuclei formed by heavy-ion reactions. The study of electromagnetic properties has become the primary source of information on nuclear structure at high spins and, also, at the warm temperatures present in the initial stage of the electromagnetic cascade process. The purpose of this paper is a review of the E1, M1, and E2 properties of such highly excited states. 42 refs., 5 figs
Multi-quark correlations in nuclei
International Nuclear Information System (INIS)
Vary, J.P.; Harindranath, A.
1986-01-01
This paper reviews the consequences of multi-quark correlations in nuclei which arise through the particular cluster decomposition of the nuclear ground state specified by the quark cluster model (QCM). The critical radius of a three quark cluster, R c , controls the formation probability of larger clusters. The value of R c = 0.50 fm is fixed by fits to deep inelastic lepton nucleus scattering data. The QCM prediction for the ratio of nuclear structure functions in the x > 1 domain is discussed as a critical test of the model. We also present an extended discussion of the application of the QCM to the nuclear Drell-Yan process. (orig.)
Experimental level densities of atomic nuclei
Energy Technology Data Exchange (ETDEWEB)
Guttormsen, M.; Bello Garrote, F.L.; Eriksen, T.K.; Giacoppo, F.; Goergen, A.; Hagen, T.W.; Klintefjord, M.; Larsen, A.C.; Nyhus, H.T.; Renstroem, T.; Rose, S.J.; Sahin, E.; Siem, S.; Tornyi, T.G.; Tveten, G.M. [University of Oslo, Department of Physics, Oslo (Norway); Aiche, M.; Ducasse, Q.; Jurado, B. [University of Bordeaux, CENBG, CNRS/IN2P3, B.P. 120, Gradignan (France); Bernstein, L.A.; Bleuel, D.L. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Byun, Y.; Voinov, A. [Ohio University, Department of Physics and Astronomy, Athens, Ohio (United States); Gunsing, F. [CEA Saclay, DSM/Irfu/SPhN, Cedex (France); Lebois, L.; Leniau, B.; Wilson, J. [Institut de Physique Nucleaire d' Orsay, Orsay Cedex (France); Wiedeking, M. [iThemba LABS, P.O. Box 722, Somerset West (South Africa)
2015-12-15
It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. From the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least up to the neutron threshold. (orig.)
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.
Interactions of 10.6 GeV/n gold nuclei with light and heavy target nuclei in nuclear emulsion
International Nuclear Information System (INIS)
Cherry, M.L.; Denes-Jones, P.
1994-03-01
We have investigated the particle production and fragmentation of nuclei participating in the interactions of 10.6 GeV/n gold nuclei in nuclear emulsions. A new criteria has been developed to distinguish between the interactions of these gold nuclei with the light (H, C, N, O) and heavy (Ag, Br) target nuclei in the emulsion. This has allowed separate analyzes of the multiplicity and pseudo-rapidity distributions of the singly charged particles emitted in Au-(H, C, N, O) and Au-(Ag, Br) interactions, as well as of the models of breakup of the projectile and target nuclei. The pseudo-rapidity distributions show strong forward asymmetries, particularly for the interactions with the light nuclei. Heavy target nuclei produce a more severe breakup of the projectile gold nucleus than do the lighter targets. A negative correlation between the number of fragments emitted from the target nuclei and the degree of centrality of the collisions has been observed, which can be attributed to the total destruction of the relatively light target nuclei by these very heavy projectile nuclei. (author). 14 refs, 11 figs, 1 tab
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; 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; 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; Moreira De Godoy, Denise Aparecida; 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; 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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...
Potentials of interaction between medium energy particles and nuclei
International Nuclear Information System (INIS)
Berezhnoj, Yu.A.; Molev, A.S.
1986-01-01
The potential of interaction between mean-energy particles and atomic nuclei is determined as a solution of an integral equation relating it to the scattering matrix. Potentials involving the central and spin-orbital or isospin parts are reconstructed on the basis of the scattering matrix of the diffraction model. Approximated expressions for central and spin-orbital potentials in the case of weak refraction are obtained. The effect of nuclear parameters on the shape of central potential of interaction between 156 MeV protons and the 208 Pb nuclei is considered. The calculated and phenomenological central and spin-orbital potentials of interaction between 185 MeV protons and the 90 Zr, 208 Pb nuclei are in good agreement only in the surface region of nuclei. The central and isospin potentials of interaction between the 3 He nuclei with 217 MeV energy and the 9 Be nuclei are studied
Kudryavtsev, Sergey M.
1995-03-01
A high-precise analytical theory of a satellite in orbit around a non-spherical planet has been developed. The Poisson's small parameter method has been used. All secular and short-periodic perturbations proportional up to and including a product of five arbitrary harmonic coefficients of the planetary expansion are calculated. Long-periodic perturbations are derived with the accuracy of up to the fourth-order, inclusive. The influence of the high-order perturbations on the motion of ERALON-1 satellite has been investigated. The results of comparison of the numerical and analytical integration of the equations of its motion over a five year interval are as follows: the r.m.s difference between the positions is 1.1 cm; and the r.m.s. difference between the ranges is 0.5 cm. The theory is intended to be used for processing precise laser range measurements of the Earth geodynamical satellites over long-term intervals.
International Nuclear Information System (INIS)
Nishizawa, Tomoaki; Sugimoto, Nobuo; Matsui, Ichiro; Shimizu, Atsushi; Okamoto, Hajime
2011-01-01
We developed backward and forward types of algorithms for estimating the vertical profiles of extinction coefficients at 532 nm for three component aerosols (water-soluble, dust, and sea salt) using three-channel Mie-scattering lidar data of the backscatter (β) at 532 and 1064 nm and the depolarization ratio (δ) at 532 nm. While the water-soluble and sea-salt particles were reasonably assumed to be spherical, the dust particles were treated as randomly oriented spheroids to account for their nonsphericity. The introduction of spheroid models enabled us to more effectively use the three-channel data (i.e., 2β+1δ data) and to reduce the uncertainties caused by the assumption of spherical dust particles in our previously developed algorithms. We also performed an extensive sensitivity study to estimate retrieval errors, which showed that the errors in the extinction coefficient for each aerosol component were smaller than 30% (60%) for the backward (forward) algorithm when the measurement errors were ±5%. We demonstrated the ability of the algorithms to partition aerosol layers consisting of three aerosol components by applying them to shipborne lidar data. Comparisons with sky radiometer measurements revealed that the retrieved optical thickness and angstrom exponent of aerosols using the algorithms developed in this paper agreed well with the sky radiometer measurements (within 6%).
Tripathy, Mukta; Schweizer, Kenneth S.
2009-06-01
We extend and apply the nonlinear Langevin equation theory of activated barrier hopping dynamics in glassy fluids and colloidal suspensions to study broad families of one-, two-, and three-dimensional hard nonspherical particles. Beyond the ideal kinetic arrest volume fraction, entropic barriers emerge with heights (alpha relaxation times, inverse diffusion constants) that increase nonlinearly (nonexponentially) with volume fraction and in a manner that becomes stronger with particle dimensionality. Partial collapse of the volume fraction dependence of barrier heights and reduced relaxation times of different particle shapes within a fixed dimensionality class are achieved based on a difference volume fraction variable that quantifies the distance from the ideal mode coupling theory dynamic crossover. However, the barrier, alpha relaxation time, and self-diffusion constant results of all shapes are remarkably well collapsed onto a single universal master curve based on a theoretically motivated coupling constant which quantifies the renormalized mean square force on a tagged particle. The latter is determined mainly by the square of the intermolecular site-site contact value of the pair correlation function, thereby providing an explicit microscopic connection between local packing, binary collisions, and slow dynamics. A large variation of the dynamic fragility with particle shape is found with compact cluster particles being the most fragile. A kinetic glass transition map is constructed that is relevant to vitrification of laboratory colloidal suspensions. The possible relevance of the hard particle results for understanding the dynamic fragility of thermal van der Waals liquids is discussed.
Experiments with stored relativistic exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Geissel, H.; Radon, T.; Attallah, F. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)] [and others
1998-07-01
Beams of relativistic exotic nuclei were produced, separated and investigated with the combination of the fragment separator FRS and the storage ring ESR. The following experiments are presented: (1) Direct mass measurements of relativistic nickel and bismuth projectile fragments were performed using Schottky spectrometry. Applying electron cooling, the relative velocity spread of the circulating secondary nuclear beams of low intensity was reduced to below 10{sup -6}. The achieved mass resolving power of m/{Delta}m = 6.5 . 10{sup 5} (FWHM) in recent measurements represents an improvement by a factor of two compared to our previous experiments. The previously unknown masses of more than 100 proton-rich isotopes have been measured in the range of 54 {<=} Z {<=} 84. The results are compared with mass models and estimated values based on extrapolations of experimental values. (2) Exotic nuclei with half-lives shorter than the time required for electron cooling can be investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique has been successfully applied in a first measurement with nickel fragments. A mass resolving power of m/{Delta}m = 1.5 . 10{sup 5} (FWHM) was achieved in this mode of operation. (3) Nuclear half-lives of stored and cooled bare projectile fragments have been measured to study the influence of the ionic charge state on the beta-decay probability. (orig.)
Approximate particle number projection in hot nuclei
International Nuclear Information System (INIS)
Kosov, D.S.; Vdovin, A.I.
1995-01-01
Heated finite systems like, e.g., hot atomic nuclei have to be described by the canonical partition function. But this is a quite difficult technical problem and, as a rule, the grand canonical partition function is used in the studies. As a result, some shortcomings of the theoretical description appear because of the thermal fluctuations of the number of particles. Moreover, in nuclei with pairing correlations the quantum number fluctuations are introduced by some approximate methods (e.g., by the standard BCS method). The exact particle number projection is very cumbersome and an approximate number projection method for T ≠ 0 basing on the formalism of thermo field dynamics is proposed. The idea of the Lipkin-Nogami method to perform any operator as a series in the number operator powers is used. The system of equations for the coefficients of this expansion is written and the solution of the system in the next approximation after the BCS one is obtained. The method which is of the 'projection after variation' type is applied to a degenerate single j-shell model. 14 refs., 1 tab
Studies of nuclei using radioactive beams
International Nuclear Information System (INIS)
Piercey, R.B.
1989-07-01
The 12 month period from May 1988 to July 1989 represents the first full year of our 18 month pilot program in nuclear structure research. In this period, research was initiated to develop a capability for radioactive secondary beams at Argonne National Laboratory using the Atlas and the new Fragment Mass Analyzer (FMA), which is currently under construction. Two major new detector facilities are currently in the final stages of design and testing. The Large-Area, Scintillator Telescope (LAST) detector is fully operational and will be shipped to Argonne National Laboratory in August for fit-tests and in-beam calibrations. The first segments of a new sixteen-segment neutron multiplicity detector have been built and tested. The remaining segments are currently being constructed. Research was continued in the areas of (1) Coulomb excitation studies of rare earth and actinide nuclei; (2) In-beam, gamma-ray spectroscopy of nuclei in the mass 100 region, and (3) Advanced detector design. Several journal articles and abstracts were published or submitted for publication in the reporting period, and others are currently in preparation. Three graduate students participated in the program, one from the University of Florida and two from the Royal Institute of Technology, Stockholm, Sweden
STELLAR TRANSITS IN ACTIVE GALACTIC NUCLEI
International Nuclear Information System (INIS)
Béky, Bence; Kocsis, Bence
2013-01-01
Supermassive black holes (SMBHs) are typically surrounded by a dense stellar population in galactic nuclei. Stars crossing the line of site in active galactic nuclei (AGNs) produce a characteristic transit light curve, just like extrasolar planets do when they transit their host star. We examine the possibility of finding such AGN transits in deep optical, UV, and X-ray surveys. We calculate transit light curves using the Novikov-Thorne thin accretion disk model, including general relativistic effects. Based on the expected properties of stellar cusps, we find that around 10 6 solar mass SMBHs, transits of red giants are most common for stars on close orbits with transit durations of a few weeks and orbital periods of a few years. We find that detecting AGN transits requires repeated observations of thousands of low-mass AGNs to 1% photometric accuracy in optical, or ∼10% in UV bands or soft X-ray. It may be possible to identify stellar transits in the Pan-STARRS and LSST optical and the eROSITA X-ray surveys. Such observations could be used to constrain black hole mass, spin, inclination, and accretion rate. Transit rates and durations could give valuable information on the circumnuclear stellar clusters as well. Transit light curves could be used to image accretion disks with unprecedented resolution, allowing us to resolve the SMBH silhouette in distant AGNs.
Extreme breathing excitations of atomic nuclei
International Nuclear Information System (INIS)
Antonov, A.N.; Nikolaev, V.A.; Petkov, I.Zh.
1984-01-01
In the present paper collective breathing nuclear states, that appear in the framework of the coherent density fluctuation model (CFM) are taken into consideration. Their excitation energies are large and comparable with the binding nuclear energies. The basic CFM equation obtain in the generator-coordinate method. The possible mechanisms for the excitations for the excitations of the breathing states are deeply inelastic interactions of particles (e - , p, etc.) with nuclei, the π - -absorbtion from nuclei. It should be noted, that the energy of the Roper-resonance is comparable with the breathing nuclear excitation energies. Therefore the decay of this resonance, in principle, can lead to the breathing nuclear vibrations. The results of this work, as well as the results of some papers, obtained by means of a similar method but related to different quantum-mechanical systems, give an evidence, that the structure in detail and the character of the forces between the particles are not decisive for the considered type of excitations
Birth, life and death of hot nuclei
International Nuclear Information System (INIS)
Suraud, E.; Tamain, B.; Gregoire, C.
1989-01-01
Intermediate energy heavy-ions (10-100 MeV/u) are the most powerful tool to study hot nuclear matter properties. In this paper we give a review of experimental and theoretical works which support this statement. The first challenge is to achieve hot nuclei formation. The second one is to study their properties. The formation step is governed by the relative influence of nucleon-nucleon collisions and mean field effects. Fundamental quantities such as excited matter decay time, thermalization time, relaxation time for collective modes are of major importance and are compared with typical collision times. It appears that semi-classical theories are able to give a reasonable description of the collision and that they are a good guide for defining further experiments. We show how it has been possible to experimentally establish that very hot equilibrated nuclei are really formed. Their decay properties are not basically different from decay properties at lower bombarding energy. However specific channels are open: in that sense, we take stock of the multifragmentation process. Moreover, compression effects may be an important feature of this energy range. Future studies will involve heavier projectiles around 30-50 MeV/u. They will be the best probe for hot and compressed nuclear matter studies
Disappearance of Collective Motion in Hot Nuclei
Santonocito, D.; Blumenfeld, Y.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Delaunay, F.; Del Zoppo, A.; Finocchiaro, P.; Frascaria, N.; Hongmei, F.; Lima, V.; Maiolino, C.; Migneco, E.; Piattelli, P.; Sapienza, P.; Scarpaci, J. A.
2005-12-01
The evolution of the GDR γ yield as a function of excitation energy has been investigated in nuclei of mass A ≈ 126 - 136 through the reactions 116Sn + 12C at 17 and 23A MeV and the reaction 116Sn + 24Mg at 17A MeV. Hot nuclei produced in incomplete fusion reactions span an excitation energy range between 160 and 290 MeV. Gamma-rays were detected with MEDEA array in coincidence with residues detected in MACISTE. The evolution of the GDR parameters has been investigated as a function of the linear momentum transferred to the fused system. The analysis of the γ spectra and their comparison with CASCADE calculations is presented. A comparison with the gamma spectra measured in the reaction 36Ar + 98Mo at 37A MeV at higher excitation energy is presented. A progressive reduction of γ multiplicity with respect to predictions for 100% of the Energy Weighted Sum Rule is observed above 200 MeV excitation energy.
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
Experiments with stored relativistic exotic nuclei
International Nuclear Information System (INIS)
Klepper, O.; Attallah, F.; Beckert, K.; Bosch, F.; Dolinskiy, A.; Eickhoff, H.; Franczak, B.; Franzke, B.; Geissel, H.; Hausmann, M.; Hellstroem, M.; Herfurth, F.; Kluge, H.-J.; Kozhuharov, C.; Muenzenberg, G.; Nolden, F.; Quint, W.; Tradon, T.; Reich, H.; Scheidenberger, C.; Schlitt, B.; Steck, M.; Suemmerer, K.; Vermeeren, L.; Winkler, M.; Winkler, Th.; Falch, M.; Kerscher, Th.; Loebner, K.E.G.; Fujita, Y.; Novikov, Yu.; Patyk, Z.; Stadlmann, J.; Wollnik, H.
1999-01-01
Beams of relativistic exotic nuclei were produced, separated and investigated with the combination of the fragment separator FRS and the storage ring ESR. The following experiments are presented: 1) Direct mass measurements of relativistic nickel and bismuth projectile fragments were performed using Schottky spectrometry. Applying electron cooling, the relative velocity spread of the circulating secondary nuclear beams of low intensity was reduced to below 10 -6 . The achieved mass resolving power of m/Δm = 6.5·10 5 (FWHM) in recent measurements represents an improvement by a factor of two compared to authors' previous experiments. The previously unknown masses of more than 100 proton-rich isotopes have been measured in the range of 54≤Z≤84. The results are compared with mass models and estimated values based on extrapolations of experimental values. 2) Exotic nuclei with half-lives shorter than the time required for electron cooling can be investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique has been successfully applied in a first measurement with nickel fragments. A mass resolving power of m/Δm = 1.5·10 5 (FWHM) was achieved in this mode of operation. 3) Nuclear half-lives of stored and cooled bare projectile fragments have been measured to study the influence of the ionic charge state on the beta-decay probability
Axial polarizability and weak currents in nuclei
International Nuclear Information System (INIS)
Ericson, M.
1977-01-01
The weak interaction nucleonic coupling constants in nuclei are modified by the presence of the neighbouring nucleons. One type of modification is due to the virtual excitation of the isobars through meson exchange. The influence of the isobars is described by means of the nuclear axial polarizability coefficient. This polarizability is known; it is linked to the p-wave πN scattering volume. A relation is derived between the axial nuclear current and the pion field which incorporates the polarizability effects. This relation has an electromagnetic analogue. It is then possible to derive the axial and pseudoscalar coupling constants from a knowledge of the pion field. This field in turn obeys a Klein-Gordon equation which has to include the isobaric excitations. The propagation of the pion field is similar to that of an electromagnetic wave in a dielectric medium. The strong interaction coupling constant is shown to be renormalized in nuclei by the effect of the various types of correlations. (author)
Exotic nuclei and radioactive beams; Noyaux exotiques et faisceaux radioactifs
Energy Technology Data Exchange (ETDEWEB)
Chomaz, P.
1996-12-31
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.
Designer Nuclei--Making Atoms that Barely Exist
Jones, Kate L.; Nazarewicz, Witold
2010-01-01
The physics of nuclei is not a democratic field. It has to be said, some nuclei are just more interesting than others. And some are more useful than others, either to explain the origins of the elements, or the nature of matter itself, or for uses in medicine and other applied fields. The trick is to work out which nuclei are going to be the most…
Spectroscopy of very heavy nuclei with a view to study super-heavy nuclei
International Nuclear Information System (INIS)
Khalfallah, F.
2007-08-01
Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No 256 et Rf 256 for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa 223 . The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)
Hyperdeformed nuclei and the residual pseudo-SU(3) symmetry
International Nuclear Information System (INIS)
Dudek, J.; Werner, T.
1988-01-01
The author discusses superdeformed and hypothetical hyperdeformed nuclei. Quadrupole deformations characteristic of these types of nuclei are defined. Symmetry features are also discussed. The characteristic cycle dependence of shell structures as functions of the deformation gives rise to chains of the deformed shell closures. Such a chain structure applies to moderately-, super- and hyper-deformed nuclei as well. The resulting total energy calculations give a systematic variation of super- and hyperdeformations with, e.g., increasing N at fixed Z, thus predicting the way nuclei deviate from the simple a:b = 2:1 and a:b = 3:1 symmetries
Deformed shapes in odd-odd nuclei near Z = 82
International Nuclear Information System (INIS)
Mukherjee, G.; Pai, H.; Bhattacharya, S.; Bhattacharya, C.; Bhattacharyya, S.; Bhattacharjee, T.; Basu, S.K.; Kundu, S.; Ghosh, T.K.; Bannerjee, K.; Rana, T.K.; Meena, J.K.; Chanda, S.; Bhowmik, R.K.; Singh, R.P.; Muralithar, S.; Garg, R.
2009-01-01
The neutron deficient nuclei in the vicinity of the Z = 82 region are known for interesting structural phenomena arising due to different shape driving effects of the proton and neutron orbitals near the Fermi surface. It has been found that the heavier bismuth and thallium nuclei with A > 200 are spherical and the lighter nuclei with A < 194 have rotational bands indicating deformation. We report here our recent experimental investigation of γ-ray spectroscopy of odd-odd Bi and Tl nuclei in mass region A = 190
Study of nuclear level densities for exotic nuclei
International Nuclear Information System (INIS)
Nasrabadi, M. N.; Sepiani, M.
2012-01-01
Nuclear level density is one of the properties of nuclei with widespread applications in astrophysics and nuclear medicine. Since there has been little experimental and theoretical research on the study of nuclei which are far from stability line, studying nuclear level density for these nuclei is of crucial importance. Also, as nuclear level density is an important input for nuclear research codes, hence studying the methods for calculation of this parameter is essential. Besides introducing various methods and models for calculating nuclear level density for practical applications, we used exact spectra distribution (SPDM) for determining nuclear level density of two neutron and proton enriched exotic nuclei with the same mass number.
Decay properties of nuclei close to Z = 108 and N = 162
Energy Technology Data Exchange (ETDEWEB)
Dvorak, Jan
2007-07-12
The goal of the research conducted in the frame of this thesis was to investigate the decay properties of the nuclides {sup 269-271}Hs and their daughters using an improved chemical separation and detection system. Shell stabilization was predicted in the region around Z=108 and N=162 in calculations, taking into account possible higher orders of deformations of the nuclei. The nucleus {sup 270}Hs with a closed proton and a closed neutron deformed shell, was predicted to be ''deformed doubly magic''. Nuclei around {sup 270}Hs can be produced only via fusion reactions at picobarn levels, resulting in a production rates of few atoms per day. Investigating short-lived nuclei using rapid chemical separation and subsequent on-line detection methods provides an independent and alternative means to electromagnetic on-line separators. Chemical separation of Hs in the form of HsO{sub 4} provides an excellent tool to study the formation reactions and nuclear structure in this region of the chart of nuclides due to a high overall efficiency and a very high purification factor. The goal was accomplished, as element 108, hassium, was produced in the reaction {sup 248}Cm({sup 26}Mg,xn){sup 274-x}Hs and chemically isolated. After gas phase separation of HsO{sub 4}, 26 genetically linked decay chains have been observed. These were attributed to decays of three different Hs isotopes produced in the 3-5n evaporation channels. The known decay chain of {sup 269}Hs, the 5n evaporation product, serves as an anchor point, thus allowing the unambiguous assignment of the observed decay chains to the 5n, 4n, and 3n channels, respectively. Decay properties of five nuclei have been unambiguously established for the first time, including the one for the the doubly-magic nuclide {sup 270}Hs. This hassium isotope is the next doubly magic nucleus after the well known {sup 208}Pb and the first experimentally observed even-even nucleus on the predicted N=162 neutron shell. The
Energy Technology Data Exchange (ETDEWEB)
Zweidinger, Markus
2016-06-22
In the present work the dipole strength distribution in the stable even-even isotopes {sup 92}Zr and {sup 94}Zr is investigated. To excite the nuclei from the ground state to an excited state, real photons are used. This method is called Nuclear Resonance Fluorescence. The measurements were performed at two different setups. The first one is the Darmstadt High Intensity Photon Setup (DHIPS). At DHIPS the measurements yield information about the spin quantum number and the integrated cross section. The second part of the experiments took place at the High Intensity γ-ray Source (HIγS). Here, information about the parity quantum number and the averaged branching ratio of the excited state is accessible. In total, 105 dipole excited states in the nucleus {sup 92}Zr and 124 in the isotope {sup 94}Zr are observed, most of them for the first time. The extracted dipole strength distribution is investigated for the existence of the pygmy dipole resonance that was observed in neighboring nuclei. Furthermore, in previously performed experiments on the isotope {sup 90}Zr, the spin-flip M1 resonance was observed as well. Therefore, also the magnetic dipole strength is investigated. Further, by comparison with global systematics, the two-phonon state is identified. Additionally, the averaged branching ratio is compared to the results of theoretical calculations in the framework of the statistical model.
Properties of Alpha Decay to Rotational Bands of Heavy Nuclei
Wang, Y. Z.; Gu, J. Z.; Dong, J. M.; Peng, B. B.
In the framework of the generalized liquid drop model (GLDM) and improved Royer's formula, we investigate the branching ratios and half-lives of α-decay to the members of the ground-state rotational bands of heavy even-even Fm and No isotopes. The calculated results are in good agreement with the available experimental data and some useful predictions are provided for future experiments.
Probable cluster decays from 298-336126 superheavy nuclei
International Nuclear Information System (INIS)
Priyanka, B.; Santhosh, K.P.
2015-01-01
The present paper deals with an investigation on the cluster decay of even clusters 4 He, 8,10 Be, 14 C, 18,20,22 O , 22,24,26 Ne, 28,30 Mg and odd clusters 15 N, 23 F, 25 Ne, 29 Mg from both the even-even and even-odd isotopes of Z=126, which has helped in predicting the neutron magicity beyond N=126
Quarks and gluons in hadrons and nuclei
International Nuclear Information System (INIS)
Close, F.E.
1989-12-01
These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. This lecture discusses the distribution functions of quarks and gluons in nucleons and nuclei, and how knowledge of these is necessary before some quark-gluon plasma searches can be analyzed. 56 refs., 2 figs
The resonance neutron fission on heavy nuclei
Kopach, Yu N; Furman, V I; Alfimenkov, V P; Lason', L; Pikelner, L B; Gonin, N N; Kozlovskij, L K; Tambovtsev, D I; Gagarskij, A M; Petrov, G A; Sokolov, V E
2001-01-01
A new approach to the description of the fission, similar to the well-known reaction theory and based on the helicity representation for the exit fission channels, is briefly summarized. This approach allows one to connect the multimodal fission representation with A. Bohr's concept of the fission transition states and to obtain formulae for the partial and differential fission cross sections. The formulae are used for analysis of the angular anisotropy of fragments in the neutron resonance induced fission of aligned sup 2 sup 3 sup 5 U nuclei and of the P-even angular forward-backward and right-left correlations of fragments oe the P-odd correlations caused by the interference of s- and p-wave neutron resonances
Quarks and gluons in hadrons and nuclei
Energy Technology Data Exchange (ETDEWEB)
Close, F.E. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA))
1989-12-01
These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. This lecture discusses the distribution functions of quarks and gluons in nucleons and nuclei, and how knowledge of these is necessary before some quark-gluon plasma searches can be analyzed. 56 refs., 2 figs.
Shell model calculations for exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Brown, B.A. (Michigan State Univ., East Lansing, MI (USA)); Warburton, E.K. (Brookhaven National Lab., Upton, NY (USA)); Wildenthal, B.H. (New Mexico Univ., Albuquerque, NM (USA). Dept. of Physics and Astronomy)
1990-02-01
In this paper we review the progress of the shell-model approach to understanding the properties of light exotic nuclei (A < 40). By shell-model'' we mean the consistent and large-scale application of the classic methods discussed, for example, in the book of de-Shalit and Talmi. Modern calculations incorporate as many of the important configurations as possible and make use of realistic effective interactions for the valence nucleons. Properties such as the nuclear densities depend on the mean-field potential, which is usually separately from the valence interaction. We will discuss results for radii which are based on a standard Hartree-Fock approach with Skyrme-type interactions.
A close look at Seyfert 2 nuclei
International Nuclear Information System (INIS)
Fischer, Sebastian; Smajic, S; Valencia-S, M; Vitale, A; Zuther, J; Eckart, A
2012-01-01
We present SINFONI adaptive optics assisted and seeing limited NIR integral field spectroscopy of the central hundreds of pc of ten z < 0.01 Seyfert 2 galaxies. The main goal of this study is to assess the significance of star formation and extinction in the circumnuclear region of Seyfert 2s. The immediate surroundings of the nuclei are resolved at linear scales of about 50-100 parsecs for most of the observed sources. The intensity and line-of-sight velocity distribution of different species is derived from the 3D SINFONI data by calculating the higher order moments of the emission lines. As part of this work in progress, the resulting maps are currently analyzed following the approach of generalized surface photometry, which allows us to identify the multiple kinematical components in the circumnuclear region of Seyfert 2s.
Optical Variability of Active Galactic Nuclei
Energy Technology Data Exchange (ETDEWEB)
Kozłowski, Szymon, E-mail: simkoz@astrouw.edu.pl [Astronomical Observatory, University of Warsaw, Warsaw (Poland)
2017-09-21
Variability studies of active galactic nuclei (AGNs) typically use either power spectral density (PSD) and structure function (SF) analyses or direct modeling of light curves with the damped random walk (DRW) and the continuous autoregressive moving average (CARMA) models. A fair fraction of research publications on the subject are flawed, and simply report incorrect results, because they lack a deep understanding of where these methods originate from and what their limitations are. For example, SF analyses typically lack or use a wrong noise subtraction procedure, leading to flat SFs. DRW, on the other hand, can only be used if the experiment length is sufficient, at least ten times the signal decorrelation time scale τ, and if the data show the power-law SF slope of γ ≡ 0.5.
Production of polarized vector mesons off nuclei
International Nuclear Information System (INIS)
Kopeliovich, B. Z.; Nemchik, J.; Schmidt, Ivan
2007-01-01
Using the light-cone QCD dipole formalism we investigate manifestations of color transparency (CT) and coherence length (CL) effects in electroproduction of longitudinally (L) and transversally (T) polarized vector mesons. Motivated by forthcoming data from the HERMES experiment we predict both the A and Q 2 dependence of the L/T ratios for ρ 0 mesons produced coherently and incoherently off nuclei. For an incoherent reaction the CT and CL effects add up and result in a monotonic A dependence of the L/T ratio at different values of Q 2 . In contrast, for a coherent process the contraction of the CL with Q 2 causes an effect opposite to that of CT and we expect quite a nontrivial A dependence
Alpha-like resonances in nuclei
Baran, V. V.; Delion, D. S.
2018-03-01
We investigate normal dipole oscillations in a system of protons, neutrons and α-particles within the Brink approach. We introduce an effective mass of α-clusters in terms of the spectroscopic factor. The Pauli exclusion principle is taken into account by using the Wildermuth rule. The ratio between alpha and giant resonance energy weighted sum rule (EWSR) is investigated for N = Z and N> Z systems. In both cases we notice an unexpected decrease of this ratio versus the increase of the spectroscopic factor. Due to this fact the possibility to experimentally detect α-like oscillations is enhanced in nuclei above 100Sn. The occurrence of the pygmy mode in N> Z systems decreases the EWSR for the α-like oscillations.
Parity nonconservation in /sup 19/F nuclei
Energy Technology Data Exchange (ETDEWEB)
Elsener, K.; Gruebler, W.; Koenig, V.; Schmelzbach, P.A.; Ulbricht, J.; Vuaridel, B.; Singy, D.; Forstner, C.; Zhang, W.Z.
1987-01-12
The parity nonconserving asymmetry A/sub ..gamma../ in the decay of polarized /sup 19/F/sup */(110 keV) nuclei has been measured. A value of A/sub ..gamma../=-(6.83 +- 2.11) x 10/sup -5/ (total error) was found. Systematic errors are extensively investigated and found to be small. The absolute normalization is given by the /sup 19/F/sup */ polarization, which is found to be rho/sub F/=-0.52 +- 0.08 in a separate experiment, using a calibrated Compton polarimeter. The new result A/sub ..gamma../(/sup 19/F) is compared to earlier experiments and recent theoretical calculations. From an analysis including /sup 18/F and /sup 21/Ne results, constraints on the weak meson-nucleon coupling constants f/sub ..pi../ and h/sub rho//sup 0/ are deduced. Agreement with calculations based on the standard electroweak theory and QCD is found.
Pion photoproduction on very light nuclei
International Nuclear Information System (INIS)
Botton, N. de
1981-01-01
The most fruitful frame of interpretation of pion photoproduction on nuclei is a microscopic description which involves - the elementary pion photoproduction amplitude on the nucleon, - the structure of the initial and final nuclear states, - the many-body effects which include the distortion of the pion wave resulting from its strong interaction with the nucleus. According to the specific nature of the performed experiments we have gained knowledge on the elementary photoproduction multipole amplitudes, on the nuclear form factors and on the pion propagation inside the nucleus; we have got some hints on the Δ-nucleon interaction and some of us have been speculating about the manifestation of exotic dibaryonic states. A few selected examples of recent experimental and theoretical work are presented which illustrate, from the point of view of an experimentalist, the possibilities and the limitations of this method of investigation. Some forthcoming developments in the field are also reported. (Auth.)
The resonance neutron fission on heavy nuclei
International Nuclear Information System (INIS)
Kopach, Yu.N.; Popov, A.B.; Furman, V.I.; Alfimenkov, V.P.; Lason', L.; Pikel'ner, L.B.; ); Gonin, N.N.; Kozlovskij, L.K.; Tambovtsev, D.I.; Gagarskij, A.M.; Petrov, G.A.; Sokolov, V.E.
2001-01-01
A new approach to the description of the fission, similar to the well-known reaction theory and based on the helicity representation for the exit fission channels, is briefly summarized. This approach allows one to connect the multimodal fission representation with A. Bohr's concept of the fission transition states and to obtain formulae for the partial and differential fission cross sections. The formulae are used for analysis of the angular anisotropy of fragments in the neutron resonance induced fission of aligned 235 U nuclei and of the P-even angular forward-backward and right-left correlations of fragments oe the P-odd correlations caused by the interference of s- and p-wave neutron resonances [ru
Decay of Hot Nuclei at Low Spins Produced by Antiproton-Annihilation in Heavy Nuclei
2002-01-01
% PS208 \\\\ \\\\ The objective of the experiment is to study (i) the thermal excitation energy distribution of antiproton-induced reactions in heavy nuclei and (ii) the decay properties of hot nuclei at low spins via evaporation, multifragmentation and fission as a function of excitation energy. The experimental set-up consists of 4-$\\pi$ detectors: the Berlin Neutron Ball~(BNB) which is a spherical shell of gadolinium-loaded scintillator liquid with an inner and outer diameter of 40 and 160~cm, respectively. This detector counts the number of evaporated neutrons in each reaction. Inside BNB there is a 4-$\\pi$ silicon ball~(BSIB) with a diameter of 20~cm consisting of 162 detectors which measure energy and multiplicity of all emitted charged nuclear particles. The particles are identified via time of flight, energy and pulse shape correlations.
Exotic nuclei: α-decay, direct reactions and structure
International Nuclear Information System (INIS)
Jain, Arun K.
2003-01-01
With input parameters from the microscopic studies of stable nuclei and their variations with respect to energy, density, asymmetry etc. one expects to describe the decay of unstable nuclei, their microscopic structure and various scattering and reaction cross sections. The exotic nuclei, both in the lower-mass region as well as in the super-heavy region also should be accessible for predictions and verification. Somehow the direct nuclear reactions of the transfer and knockout type, employed to investigate quantitatively the microscopic behaviour of nuclei, have been only marginally successful. Successful resolution of some of the striking gross disagreements between theory and observations has been achieved now. The manner in which information of the microscopic structure and the effective nuclear interaction affect the predictive power of the direct reactions is found to be remarkable. In the α-decay of heavy nuclei also the microscopic structure information of the target and residual nuclei play decisive role in the values of decay energy and half-life. The interior and surface parts of the α-particle residual nucleus effective interaction, control the energy and decay rates. Fitting the observations with microscopic model values lead to the required predictive power for decay properties of super-heavy nuclei. In a similar manner the analysis of scattering and reactions involving light exotic-nuclei gives information about their microscopic structure. (author)
Mass Measurements of Proton-rich Nuclei with JYFLTRAP
Eronen, Tommi
2011-01-01
The Penning trap setup JYFLTRAP, connected to the IGISOL facility, has been extensively used for atomic mass measurements of exotic nuclei. On the proton rich side of the chart of nuclei mass measurements have mostly contributed to fundamental physics and nuclear astrophysics studies with about 100 atomic masses measured.
Detector for recoil nuclei stopping in the spark chamber gas
International Nuclear Information System (INIS)
Aleksanyan, A.S.; Asatiani, T.L.; Ivanov, V.I.; Mkrtchyan, G.G.; Pikhtelev, R.N.
1974-01-01
A detector consisting of the combination of a drift and a wide gap spark chambers and designed to detect recoil nuclei stopping in the spark chamber gas is described. It is shown, that by using an appropriate discrimination the detector allows to detect reliably the recoil nuclei in the presence of intensive electron and γ-quanta beams
4th International Conference on Exotic Nuclei and Atomic Masses
Gross, Carl J; Rykaczewski, Krzysztof P; The European Physical Journal A : Volume 25, Supplement 1, 2005
2005-01-01
The International Conference on Exotic Nuclei and Atomic Masses (ENAM) has gained the status of the premier meeting for the physics of nuclei far from stability. The selected and refereed papers presenting the main results constitute valuable proceedings that offer everyone working in this field an authoritative and comprehensive source of reference.
Analysis of Orientation Relations Between Deformed Grains and Recrystallization Nuclei
DEFF Research Database (Denmark)
West, Stine S.; Winther, Grethe; Juul Jensen, Dorte
2011-01-01
Nucleation in 30 pct rolled high-purity aluminum samples was investigated by the electron backscattering pattern method before and after annealing. A total of 29 nuclei including two twins were observed, and approximately one third of these nuclei had orientations not detected in the deformed sta...
Study of cosmic ray nuclei detection by an image calorimeter
Energy Technology Data Exchange (ETDEWEB)
Casolino, M.; Sparvoli, R.; Morselli, A.; Picozza, P. [Rome Univ. `Tor Vergata` (Italy)]|[INFN, Sezione Univ. `Tor Vergata` Rome (Italy); Ozerov, Yu.V.; Zemskov, V.M.; Zverev, V.G.; Galper, A.M. [Moscow Engineering Physics Institute, Moscow (Russian Federation); Carlson, P. [Royal Institute of Technology, Stockholm (Sweden); Fuglesang, C. [ESA-EAC, Cologne (Germany)
1995-09-01
It is shown that a cosmic gamma-ray telescope made of a multilayer silicon tracker and a imaging CsI calorimeter, is capable of identifying cosmic ray nuclei. The telescope charge resolution is estimated around 4% independently of charge. Simulation methods are used to determine the telescope properties for nuclei detection.
Spectroscopic factors for two-proton radioactive nuclei
Indian Academy of Sciences (India)
Abstract. Spectroscopic factors for two-proton emitting nuclei are discussed in the framework of the BCS (Bardeen–Cooper–Schriefer) model. Calculations carried out for the two-proton unstable 45Fe, 48Ni and 54Zn nuclei are presented.
Determination of F-spin symmetry in deformed nuclei
International Nuclear Information System (INIS)
Ginocchio, J.N.; Kuyucak, S.
1991-01-01
The purity of a neutron-proton symmetry called F-spin is estimated in collective nuclei. Two simple formulae are shown to provide a quick and accurate estimate for F-spin admixtures in the ground band. Conclusions are also drawn about quadrupole effective charges in collective nuclei. 11 refs., 2 figs
Cosmic Ray Nuclei in the Fermi-LAT ACD
Green, David; Hays, E. A.; Brandt, T. J.
2014-01-01
The Anti-Coincidence Detector (ACD) of the Fermi Large Area Telescope (LAT) serves to identify charged particles, which cross the LAT at a rate orders of magnitude higher than that of the gamma-ray signal. We have developed a method that uses cosmic-ray nuclei, Z > 3, as a calibration source to improve charge resolution of the light deposit measurement in the ACD at high light levels. Improving the charge resolution of the ACD gives the LAT an additional tool for cosmic-ray nuclei charge discrimination and therefore enhances the LAT's capability for analysis of cosmic-ray nuclei. In this analysis, we are able to distinguish eight cosmic-ray nuclei: boron, carbon, nitrogen, oxygen, neon, magnesium, silicon and iron in the LAT ACD's data. We present the results of our method, and demonstrate improved charge resolution for cosmic-ray nuclei in the ACD.
Synthesis of Superheavy Nuclei with Z = 112 - 118
Utyonkov, V. K.
2015-06-01
Review of the discovery and investigation of the "Island of stability" of superheavy nuclei at the separator DGFRS in the 238U-249Cf+48Ca reactions is presented. The synthesis of the heaviest nuclei, their decay properties, and methods of identification are discussed. The results are compared with the data obtained in the chemistry experiments performed at the IVO+COLD setup and at the separators SHIP, BGS, and TASCA. The role of shell effects in the stability of superheavy nuclei is demonstrated by comparison of the experimental and theoretical data. The recent experiment aimed at the investigation of the region of neutron-deficient nuclei produced in the 239Pu+48Ca reaction is described. Future experiments at DGFRS aimed at the study of superheavy nuclei are considered.
Yang, Minglin; Wu, Yueqian; Sheng, Xinqing; Ren, Kuan Fang
2017-12-01
Computation of scattering of shaped beams by large nonspherical particles is a challenge in both optics and electromagnetics domains since it concerns many research fields. In this paper, we report our new progress in the numerical computation of the scattering diagrams. Our algorithm permits to calculate the scattering of a particle of size as large as 110 wavelengths or 700 in size parameter. The particle can be transparent or absorbing of arbitrary shape, smooth or with a sharp surface, such as the Chebyshev particles or ice crystals. To illustrate the capacity of the algorithm, a zero order Bessel beam is taken as the incident beam, and the scattering of ellipsoidal particles and Chebyshev particles are taken as examples. Some special phenomena have been revealed and examined. The scattering problem is formulated with the combined tangential formulation and solved iteratively with the aid of the multilevel fast multipole algorithm, which is well parallelized with the message passing interface on the distributed memory computer platform using the hybrid partitioning strategy. The numerical predictions are compared with the results of the rigorous method for a spherical particle to validate the accuracy of the approach. The scattering diagrams of large ellipsoidal particles with various parameters are examined. The effect of aspect ratios, as well as half-cone angle of the incident zero-order Bessel beam and the off-axis distance on scattered intensity, is studied. Scattering by asymmetry Chebyshev particle with size parameter larger than 700 is also given to show the capability of the method for computing scattering by arbitrary shaped particles.
Particle Acceleration in Active Galactic Nuclei
Miller, James A.
1997-01-01
The high efficiency of energy generation inferred from radio observations of quasars and X-ray observations of Seyfert active galactic nuclei (AGNs) is apparently achieved only by the gravitational conversion of the rest mass energy of accreting matter onto supermassive black holes. Evidence for the acceleration of particles to high energies by a central engine is also inferred from observations of apparent superluminal motion in flat spectrum, core-dominated radio sources. This phenomenon is widely attributed to the ejection of relativistic bulk plasma from the nuclei of active galaxies, and accounts for the existence of large scale radio jets and lobes at large distances from the central regions of radio galaxies. Reports of radio jets and superluminal motion from galactic black hole candidate X-ray sources indicate that similar processes are operating in these sources. Observations of luminous, rapidly variable high-energy radiation from active galactic nuclei (AGNs) with the Compton Gamma Ray Observatory show directly that particles are accelerated to high energies in a compact environment. The mechanisms which transform the gravitational potential energy of the infalling matter into nonthermal particle energy in galactic black hole candidates and AGNs are not conclusively identified, although several have been proposed. These include direct acceleration by static electric fields (resulting from, for example, magnetic reconnection), shock acceleration, and energy extraction from the rotational energy of Kerr black holes. The dominant acceleration mechanism(s) operating in the black hole environment can only be determined, of course, by a comparison of model predictions with observations. The purpose of the work proposed for this grant was to investigate stochastic particle acceleration through resonant interactions with plasma waves that populate the magnetosphere surrounding an accreting black hole. Stochastic acceleration has been successfully applied to the
Energy Technology Data Exchange (ETDEWEB)
Huerstel, A
2002-11-01
This thesis is devoted to the study of very neutron deficient nuclei in the lead region of the nuclear chart and more precisely to the investigation of the single particle states and collective properties of the {sup 187,189}Bi isotopes by gamma-ray spectroscopy. These nuclei were produced via fusion-evaporation reaction induced by a krypton beam on a silver target. In this mass region, the cross section for producing these nuclei are very low, of the order of a few micro-barns, making experimental studies very difficult. The identification of the nuclei was done using the very powerful RDT (Recoil Decay Tagging) technique, based on the selection of the isotopes through their characteristic alpha-particle decays. The experiments were performed at the university of Jyvdskyla (Finland) with the facility combining the gamma-ray spectrometer JUROSPHERE and the magnetic gas-filled separator RITU. Isomeric states were observed in both nuclei and their life-times measured. The systematics of individual proton states in odd-mass bismuth isotopes have been reproduced with a shell model up to 20 neutrons away from the valley of stability. Furthermore, rotational bands, a signature of collective nuclear motion, have been established for the first time in these nuclei. The interpretation of these results led to the conclusion that {sup 187,189}Bi have a prolate shape at low excitation energy, unlike the heavier bismuth isotopes which have been interpreted to have oblate deformation, implying a shape transition in this mass region. Hartree-Fock-Bogolyubov calculations are consistent with the experimental indication of shape coexistence, as seen in the neighbouring even-even lead nuclei. (author)
Zhang, Xueqian
2001-08-01
From an experiment with GAMMMASPHERE and a 252Cf spontaneous fission source, high spin studies of several neutron-rich nuclei have been carried out. In the mass region A ~ 150, a new negative-parity band in 154Nd and new negative-parity levels in 152Nd were identified and the yrast bands were extended to 18+ in 154Nd and 20+ 152Nd in a triple gamma coincidence study. These new negative-parity bands are consistent with octupole vibrational mode rather than the stable octupole deformation seen in Ba and Ce nuclei. There is a constant difference as a function of spin between the J1 values for the negative-parity band in 152Nd and J1 for the similar negative-parity band in 154Nd, however, their J2 values are essentially identical above the 4 + state. These bands indicate a new kind of identical bands associated with an octupole vibrational mode. In mass region A ~ 110, we have observed new bands in 113,115,117,118 Pd up to moderately high spin. The newly identified negative-parity yrast band energy level systematics built on the / isomeric states fit smoothly with the known systematic for other Pd isotopes, and show a minimum excitation energy at N = 68 related to a mid-shell closure. These new negative- parity yrast bands indicate a first band crossing at ¢ω ~ 0.45 MeV, nearly identical to those seen in 109,111Pd, but significantly higher than those in the positive yrast parity bands in 113,115Pd and in the even-even Pd isotopes. We have interpreted the new negative-parity yrast bands as having band crossings from the alignment of a nh/ pair, and this suggests that 113,115,117Pd maintain a prolate shape. Additionally, we have observed two new bands in 113,115 Pd, which are tentatively assigned positive parity with band crossings about 0.25 and 0.32 MeV. These lower frequencies are consistent with a nh/ pair alignment. In the neutron-rich 118Pd, the first band crossing at a frequency of ¢ω ~ 0.29 MeV was observed in its yrast band. This band crossing frequency is
Effective field theory for halo nuclei
International Nuclear Information System (INIS)
Hagen, Philipp Robert
2014-01-01
We investigate properties of two- and three-body halo systems using effective field theory. If the two-particle scattering length a in such a system is large compared to the typical range of the interaction R, low-energy observables in the strong and the electromagnetic sector can be calculated in halo EFT in a controlled expansion in R/ vertical stroke a vertical stroke. Here we focus on universal properties and stay at leading order in the expansion. Motivated by the existence of the P-wave halo nucleus 6 He, we first set up an EFT framework for a general three-body system with resonant two-particle P-wave interactions. Based on a Lagrangian description, we identify the area in the effective range parameter space where the two-particle sector of our model is renormalizable. However, we argue that for such parameters, there are two two-body bound states: a physical one and an additional deeper-bound and non-normalizable state that limits the range of applicability of our theory. With regard to the three-body sector, we then classify all angular-momentum and parity channels that display asymptotic discrete scale invariance and thus require renormalization via a cut-off dependent three-body force. In the unitary limit an Efimov effect occurs. However, this effect is purely mathematical, since, due to causality bounds, the unitary limit for P-wave interactions can not be realized in nature. Away from the unitary limit, the three-body binding energy spectrum displays an approximate Efimov effect but lies below the unphysical, deep two-body bound state and is thus unphysical. Finally, we discuss possible modifications in our halo EFT approach with P-wave interactions that might provide a suitable way to describe physical three-body bound states. We then set up a halo EFT formalism for two-neutron halo nuclei with resonant two-particle S-wave interactions. Introducing external currents via minimal coupling, we calculate observables and universal correlations for such
Environmental properties related to active galactic nuclei
Manzer, Lianne H.
There continues to be significant controversy regarding the mechanisms responsible for the initiation of activity in galactic nuclei. It is well understood that the non-thermal energy produced by an AGN is due to accretion onto a supermassive black hole. It has not yet been determined, however, what leads particular galaxies to become active. An accurate exploration into what triggers an AGN demands an analysis of a large sample of galaxies across a diverse set of environments. In this work, we investigate possible environmental influences by carrying out a statistical investigation of galaxy groups. Using the catalogue of Yang et al. (2007), in which groups of galaxies containing between 2 and 20 members with redshifts between 0.01 -- 0.20 were taken from the Sloan Digital Sky Survey, we investigate the fraction of active galactic nuclei (AGN) within these groups and compare it to the sample of isolated galaxies also obtained from Yang et al. (2007). After correcting our spectroscopic data for extinction and underlying stellar absorption, we classify the galaxy sample using relevant emission-line ratios. We propose an alternate method for classifying emission-line galaxies, including AGN, which builds upon standard diagnostic utilities used for optical classification and includes uncertainties. Such classification probabilities offer a more robust and consistent method of investigating the effect of group environments with galaxy type. We find our sample to be a fair representation of the local universe by comparing the luminosity function of our entire data set to that of Blanton et al. (2001), Blanton et al. (2003b), and Montero-Dorta & Prada (2009). The evidence also suggests that the luminosity function of galaxies differs between isolated galaxies and galaxies in groups. We find a significant increase in the fraction of AGNs identified in grouped environments. On the other hand, we find a higher fraction of starforming galaxies within isolated systems. We
The dynamics of dense galactic nuclei
Lee, Man Hoi
In this thesis, two topics on the dynamics of dense galactic nuclei are studied. They are relevant to the formation of massive black holes and the observations of several nearby galactic nuclei. An overview of the observations is given in Chapter 1. In Chapter 2, the dynamical evolution of dense clusters of compact stars is studied. The formation of binaries and their subsequent merging by gravitational radiation emission is important to the evolution of such clusters. Aarseth's NBODY5 N-body simulation code, which is modified to include these processes, is used to simulate small N clusters with different initial velocity dispersions. The initial evolution is similar to previous results from Fokker-Planck simulations and shows orderly formation of heavy objects. However, the late evolution shows runaway growth for the most massive object in the cluster. We present arguments to show that merger by gravitational radiation (and possibly hydrodynamic merger of normal stars) is expected to be unstable to runaway growth. These results suggest that a seed massive black hole can be formed by runaway growth in a dense cluster of compact stars. In Chapter 3, the effects of stellar encounters on rotating stellar systems with central massive black holes are studied. For axisymmetric stellar systems with distribution functions that depend only on the energy E and the angular momentum about one axis Jx, the steady-state stellar distribution is found by directly integrating the Fokker-Planck equation in E, J subx) space. Two sets of models with simple assumptions about the loss cone in phase space (due to loss of stars to the central black hole) are presented: the loss cone in the Jx direction is either ignored or completely empty. We find that the depletion of stars due to an empty loss cone is significant. Density and kinematic profiles are also presented. The ratio of rotation velocity to velocity dispersion, V/sigma at small radii is higher than that of the background
Alpha decay properties of superheavy nuclei Z = 126
Manjunatha, H. C.
2016-01-01
We have studied the possible isotopes of superheavy nuclei Z = 126 in the range 288 ≤ A ≥ 339 by studying through their α-decay properties. α-Decay half-life for the isotopes of Z = 126 superheavy nuclei in the range 288 ≤ A ≥ 339 is performed within the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The calculated α half-lives agree with the values computed using the Viola-Seaborg systematic, the universal curve of Poenaru et al. (2011) [61]; (2012) [62] and the analytical formulas of Royer (2000) [63]. To identify the mode of decay of these isotopes, the spontaneous-fission half-lives were also evaluated using the semiempirical relation given by Xu et al. (2008) [72]. As we could observe α chains consistently from the nuclei 288-306126, we have predicted that these nuclei could not be synthesized and detected experimentally via α decay as their decay half-lives are too small, which span the order 10-9 to 10-6 s. Most of the predicted, unknown nuclei in the range 307 ≤ A ≥ 326 were found to have relatively long half-lives. Of these the nuclei 307126, 318126, 319126, 320126 and 323-326126 were found to have long half-lives and hence could be sufficient to detect them if synthesized in a laboratory.
Calorimetric signatures of human cancer cells and their nuclei
Energy Technology Data Exchange (ETDEWEB)
Todinova, S. [Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, Sofia 1113 (Bulgaria); Stoyanova, E. [Department of Molecular Immunology, Institute of Biology and Immunology of Reproduction, Bulgarian Academy of Sciences, Tzarigradsko shose Blvd. 73, Sofia 1113 (Bulgaria); Krumova, S., E-mail: sakrumo@gmail.com [Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, Sofia 1113 (Bulgaria); Iliev, I. [Institute of Experimental Morphology, Pathology and Anthropology with Museum, Acad. G. Bonchev Str., Bl. 25, Sofia 1113 (Bulgaria); Taneva, S.G. [Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, Sofia 1113 (Bulgaria)
2016-01-10
Graphical abstract: - Highlights: • Two temperature ranges are distinguished in the thermograms of cells/nuclei. • Different thermodynamic properties of cancer and normal human cells/nuclei. • Dramatic reduction of the enthalpy of the low-temperature range in cancer cells. • Oxaliplatin and 5-FU affect the nuclear matrix proteins and the DNA stability. - Abstract: The human cancer cell lines HeLa, JEG-3, Hep G2, SSC-9, PC-3, HT-29, MCF7 and their isolated nuclei were characterized by differential scanning calorimetry. The calorimetric profiles differed from normal human fibroblast (BJ) cells in the two well distinguished temperature ranges—the high-temperature range (H{sub T}, due to DNA-containing structures) and the low-temperature range (L{sub T}, assigned to the nuclear matrix and cellular proteins). The enthalpy of the L{sub T} range, and, respectively the ratio of the enthalpies of the L{sub T}- vs. H{sub T}-range, ΔH{sub L}/ΔH{sub H}, is strongly reduced for all cancer cells compared to normal fibroblasts. On the contrary, for most of the cancer nuclei this ratio is higher compared to normal nuclei. The HT-29 human colorectal cancer cells/nuclei differed most drastically from normal human fibroblast cells/nuclei. Our data also reveal that the treatment of HT-29 cancer cells with cytostatic drugs affects not only the DNA replication but also the cellular proteome.
Broadband properties of active galactic nuclei
Edelson, Richard Allen
The broadband radio-infrared-optical-ultraviolet properties of active galactic nuclei are used to investigate the nature of the central engine and the surrounding environment. Optically selected quasars and Seyfert 1 galaxies tend to have relatively flat infrared spectra and low reddenings, while most Seyfert 2 galaxies and other dusty objects have steep infrared spectra and larger reddenings. The infrared spectra of most luminous radio-quiet active galaxies turn over near approx. 80 micron. It appears that the infrared spectra of most quasars and luminous Seyfert 1 galaxies are dominated by unreprocessed radiation from a synchrotron self-absorbed source of order a light day across, about the size of the hypothesized accretion disk. Seyfert 2 galaxies and other reddened objects have infrared spectra which appear to be dominated by thermal emission from warm dust, probably in the disk of the underlying galaxy. A broad emission feature, centered near 5 micron, is present in many luminous quasars and Seyfert 1 galaxies. Highly polarized objects (blazars) can be strongly variable at far infrared wavelengths over time scales of months. Seyfert galaxies tend to have steep radio spectra.
Fueling active galactic nuclei by magnetic braking
Krolik, Julian H.; Meiksin, Avery
1990-01-01
Recent detections of massive concentrations of molecular gas near the centers of galaxies hosting active nuclei suggest that these concentrations may be the source of accretion fuel for the nucleus. However, for that to be true, an angular momentum barrier must be overcome before the material in such a cloud can reach the nucleus. It is suggested that magnetic braking of the cloud may remove sufficient angular momentum to permit its material to draw considerably closer to the central object. The mechanism is particularly effective in the limit that the gas becomes self-gravitating because removal of a fraction of the initial angular momentum can lead to dynamical instability and collapse. Any small misalignment between the initial rotation axis of the cloud and the rotation axis of the galaxy can be substantially amplified as a result of the braking. It is argued that mass accretion onto the central object may occur in episodes, in some cases with a constant mass accretion rate during each episode.
TESTING TESTS ON ACTIVE GALACTIC NUCLEI MICROVARIABILITY
International Nuclear Information System (INIS)
De Diego, Jose A.
2010-01-01
Literature on optical and infrared microvariability in active galactic nuclei (AGNs) reflects a diversity of statistical tests and strategies to detect tiny variations in the light curves of these sources. Comparison between the results obtained using different methodologies is difficult, and the pros and cons of each statistical method are often badly understood or even ignored. Even worse, improperly tested methodologies are becoming more and more common, and biased results may be misleading with regard to the origin of the AGN microvariability. This paper intends to point future research on AGN microvariability toward the use of powerful and well-tested statistical methodologies, providing a reference for choosing the best strategy to obtain unbiased results. Light curves monitoring has been simulated for quasars and for reference and comparison stars. Changes for the quasar light curves include both Gaussian fluctuations and linear variations. Simulated light curves have been analyzed using χ 2 tests, F tests for variances, one-way analyses of variance and C-statistics. Statistical Type I and Type II errors, which indicate the robustness and the power of the tests, have been obtained in each case. One-way analyses of variance and χ 2 prove to be powerful and robust estimators for microvariations, while the C-statistic is not a reliable methodology and its use should be avoided.
Nuclei far from stability using exotic targets
International Nuclear Information System (INIS)
Wilhelmy, J.B.; Bentley, C.E.; Thomas, K.E.; Brown, R.E.; Flynn, E.R.; Van der Plicht, J.; Mann, L.G.; Struble, G.L.
1981-01-01
The meson factories such as the Los Alamos Meson Physics Facility have made possible high fluence medium energy proton beams that can be used for spallation reactions to produce macro quantities of unstable isotopes. Targets of over 10 g/cm 2 can be exposed to total fluence approaching 1 A-hour resulting in spallation yields in the 0.01-10 mg range for many isotopes of potential interest for nuclear structure studies. With the use of hot cell facilities, chemical processing can isolate the desired material and this coupled with subsequent isotope separation can result in usable quantities of material for nuclear target applicaton. With offstable isotopes are target materials, conventional nuclear spectroscopy techniques can be employed to study nuclei far from stability. The irradiation and processing requirements for such an operation, along with the isotope production possibilities, are discussed. Also presented are initial experiments using a 148 Gd (tsub(1/2) = 75a) target to perform the (p,t) reaction to extablish levels in the proposed double magic nucleus 146 Gd. (orig.)
A New Thermodynamics from Nuclei to Stars
Directory of Open Access Journals (Sweden)
Dieter H.E. Gross
2004-03-01
Full Text Available Abstract: Equilibrium statistics of Hamiltonian systems is correctly described by the microcanonical ensemble. Classically this is the manifold of all points in the N-body phase space with the given total energy. Due to Boltzmann's principle, eS=tr(ÃŽÂ´(E-H, its geometrical size is related to the entropy S(E,N,.... This definition does not invoke any information theory, no thermodynamic limit, no extensivity, and no homogeneity assumption, as are needed in conventional (canonical thermo-statistics. Therefore, it describes the equilibrium statistics of extensive as well of non-extensive systems. Due to this fact it is the fundamental definition of any classical equilibrium statistics. It can address nuclei and astrophysical objects as well. All kind of phase transitions can be distinguished sharply and uniquely for even small systems. It is further shown that the second law is a natural consequence of the statistical nature of thermodynamics which describes all systems with the same -- redundant -- set of few control parameters simultaneously. It has nothing to do with the thermodynamic limit. It even works in systems which are by far than any thermodynamic "limit".
High spins in gamma-soft nuclei
Energy Technology Data Exchange (ETDEWEB)
Leander, G.A.; Frauendorf, S.; May, F.R.
1982-01-01
Nuclei which are soft with respect to the ..gamma.. shape degree of freedom are expected to have many different structures coexisting in the near-yrast regime. In particular, the lowest rotational quasi-particle in a high-j shell exerts a strong polarizing effect on ..gamma... The ..gamma.. to which it drives is found to vary smoothly over a 180/sup 0/ range as the position of the Fermi level varies. This simple rule is seen to have a direct connection with the energy staggering of alternate spin states in rotational bands. A diagram is presented which provides a general theoretical reference for experimental tests of the relation between ..gamma.., spin staggering, configuration, and nucleon number. In a quasicontinuum spectrum, the coexistence of different structures are expected to make several unrelated features appear within any one slice of sum energy and multiplicity. However, it is also seen that the in-band moment of inertia may be similar for many bands of different ..gamma...
Transitions between compound states of spherical nuclei
International Nuclear Information System (INIS)
Kadmenskii, S.G.; Markushev, V.P.; Furman, V.I.
1980-01-01
Wigner's statistical matrices are used to study the average reduced g widths and their dispersion for g transitions from a compound state c to another state f, with a lower excitation energy but of arbitrary complexity, for spherical nuclei. It is found that the Porter--Thomas distribution holds for the g widths for all cases of practical interest. In g transitions between compound states c and c' with E/sub g/< or =2 MeV, the most important transitions are M1 transitions involving the major many-quasiparticle components of state c and E1 transitions involving the minor components of state c. It is shown that the strength functions predicted by the various theories for M1 and E1 transitions between compound states with E/sub g/< or =2 MeV are similar. Preference is assigned to the M1-transition version because of experimental results on (n,ga) reactions with thermal and resonance neutrons
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)
On Complex Nuclei Energetics in LENR
Miley, George H.; Hora, Heinz
2005-03-01
Swimming Electron Layer (SEL) theory plus fission of ``complex nuclei'' were proposed earlier to explain reaction products observed in electrolysis with multi-layer thin-film metallic electrodesootnotetext1.G.H. Miley, and J.A. Patterson, J. New Energy, Vol. 1, pp.11-15, (1996).. SEL was then extended to treat gas-diffusion driven transmutation experimentsootnotetextG. H. Miley and H. Hora, ``Nuclear Reactions in Solids,'' APS DNP Mtg., East Lansing, MI, Oct (2002).. It is also consistent with measured charged-particle emission during thin-film electrolysis and x-ray emission during plasma bombardment experimentsootnotetextA. Karabut, ``X-ray emission in high-current glow discharge,'' Proc., ICCF-9, Beijing China, May (2002).. The binding energy per complex nucleon can be estimated by an energy balance combined with identification of products for each complex e.g. complexes of A 39 have ˜ 0.05 MeV/Nucleon, etc, in thin film electrolysis. Energies in gas diffusion experiments are lower due to the reduced trap site potential at the multi-atom surface. In the case of x-ray emission, complexes involve subsurface defect center traps, giving only a few keV/Nucleon, consistent with experiments^3.
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.
Photodisintegration of Light Nuclei with CLAS
Energy Technology Data Exchange (ETDEWEB)
Ilieva, Yordanka Yordanova [University of South Carolina; Zachariou, Nicholas [University of South Carolina
2013-08-01
We report preliminary results of photodisintegration of deuteron and {sup 3}He measured with CLAS at Jefferson Lab. We have extracted the beam-spin asymmetry for the {vector {gamma}}d {yields} pn reaction at photon energies from 1.1 GeV to 2.3 GeV and proton center-of-mass (c.m.) angles between 35{degrees} and 135{degrees} . Our data show interesting evolution of the angular dependence of the observable as the photon energy increases. The energy dependence of the beam-spin asymmetry at 90 shows a change of slope at photon energy of 1.6 GeV. A comparison of our data with model calculations suggests that a fully non-perturbative treatment of the underlying dynamics may be able to describe the data better than a model based on hard scattering. We have observed onset of dimensional scaling in the cross section of two-body photodisintegration of {sup 3}He at remarkably low energy and momentum transfer, which suggests that partonic degrees of freedom may be relevant for the description of nuclei at energies lower than previously considered.
Electromagnetic Studies of Mesons, Nucleons, and Nuclei
Energy Technology Data Exchange (ETDEWEB)
Baker, Oliver K.
2013-08-20
Professor Baker was a faculty member at Hampton University in Hampton, Virginia, and, jointly, a Staff Physicist at Jefferson Lab in nearby Newport News from September 1989 to July 2006. The Department of Energy (DOE) funded the grant DE-FG02-97ER41035 Electromagnetic Studies of Mesons, Nucleons, and Nuclei, while Baker was in this joint appointment. Baker sent a closeout report on these activities to Hampton University’s Sponsored Research Office some years ago, shortly after joining Yale University in 2006. In the period around 2001, the research grant with Baker as the Principal Investigator (PI) was put under the supervision of Professor Liguang Tang at Hampton University. Baker continued to pursue the research while in this join appointment, however the administrative responsibilities with the DOE and with Hampton University rested with Professor Tang after 2001, to my recollection. What is written in this document is from Baker’s memory of the research activities, which he has not pursued since joining the Yale University faculty.
Searching for dual active galactic nuclei
Rubinur, K.; Das, M.; Kharb, P.
2018-02-01
Binary or dual active galactic nuclei (DAGN) are expected from galaxy formation theories. However, confirmed DAGN are rare and finding these systems has proved to be challenging. Recent systematic searches for DAGN using double-peaked emission lines have yielded several new detections, as have the studies of samples of merging galaxies. In this paper, we present an updated list of DAGN compiled from published data. We also present preliminary results from our ongoing Expanded Very Large Array (EVLA) radio study of eight double-peaked emission-line AGN (DPAGN). One of the sample galaxy shows an S-shaped radio jet. Using new and archival data, we have successfully fitted a precessing jet model to this radio source. We find that the jet precession could be due to a binary AGN with a super-massive black-hole (SMBH) separation of ˜ 0.02 pc or a single AGN with a tilted accretion disk. We have found that another sample galaxy, which is undergoing a merger, has two radio cores with a projected separation of 5.6 kpc. We discuss the preliminary results from our radio study.
Nuclear structure/nuclei far from stability
International Nuclear Information System (INIS)
Casten, R.F.; Garrett, J.D.; Moller, P.; Bauer, W.W.; Brenner, D.S.; Butler, G.W.; Crawford, J.E.; Davids, C.N.; Dyer, P.L.; Gregorich, K.; Hagbert, E.G.; Hamilton, W.D.; Harar, S.; Haustein, P.E.; Hayes, A.C.; Hoffman, D.C.; Hsu, H.H.; Madland, D.G.; Myers, W.D.; Penttila, H.T.; Ragnarsson, I.; Reeder, P.L.; Robertson, G.H.; Rowley, N.; Schreiber, F.; Seifert, H.L.; Sherrill, B.M.; Siciliano, E.R.; Sprouse, G.D.; Stephens, F.S.; Subotic, K.; Talbert, W.; Toth, K.S.; Tu, X.L.; Vieira, D.J.; Villari, A.C.C.; Walters, W.B.; Wildenthal, B.H.; Wilhelmy, J.B.; Winger, J.A.; Wohn, F.K.; Wouters, J.M.; Zhou, X.G.; Zhou, Z.Y.
1990-01-01
This report outlines some of the nuclear structure topics discussed at the Los Alamos Workshop on the Science of Intense Radioactive Ion Beams (RIB). In it we also tried to convey some of the excitement of the participants for utilizing RIBs in their future research. The introduction of radioactive beams promises to be a major milestone for nuclear structure perhaps even more important than the last such advance in beams based on the advent of heavy-ion accelerators in the 1960's. RIBs not only will allow a vast number of new nuclei to be studies at the extremes of isospin, but the variety of combinations of exotic proton and neutron configurations should lead to entirely new phenomena. A number of these intriguing new studies and the profound consequences that they promise for understanding the structure of the atomic nucleus, nature's only many-body, strongly-inteacting quantum system, are discussed in the preceeding sections. However, as with any scientific frontier, the most interesting phenomena probably will be those that are not anticipated--they will be truly new
Set-up of light nuclei multidetector
International Nuclear Information System (INIS)
Drouet, A.
1985-01-01
In order to study mechanisms of reactions produced by heavy ions in the GANIL energy range (15-100 MeV/A), a multidetector capable to detect large multiplicities for particles and light nuclei is necessary. The multidetector set up covers the 3-30 0 angular range and consists of 96 counters (NE102 plastic scintillator sheet, 2mm thick). The apparatus must identify the nuclear charge of the detected particles. Using the apparatus at GANIL leaded to carry out data processing tools in conversationnal mode and to write on experimental area programs performing and monitoring data acquisition. A test carried out with a 44 MeV/A argon beam showed that the apparatus was working properly: the identification in nuclear charge between Z=1 (proton) and Z=7 (nitrogen) is good. Results of the test allow to draw light production curves in the NE102 plastic scintillator for the following ions: 1 H, 4 He, 7 Li, 9 Be, 11 B, 12 C, 14 N, in the 13 to 44 MeV/A energy range [fr
Impacts of asteroidal material on cometary nuclei
Solc, M.; Stork, R.; Kozel, M.
1994-07-01
Impacts can bring geologically evolved asteroidal dust or lumps into cometary nuclei that consist of more primitive material. We estimate the amount of the asteroidal material captured in nucleus of some short-period comets during one revolution, during the whole lifetime of the nucleus in the inner solar system, and, finally, during the period shortly after the formation of nucleus in outer regions of the protoplanetary disk. Interplanetary dust grains registered by Galileo and Ulysses dust detectors between Venus and Jupiter together with IRAS photometry of dust in asteroidal band provided us with the basic data for estimating the dust concentration in space at various places not far from the ecliptic. Another basis was the five populations of interplanetary meteoroids proposed by Divine and the paper on influx of interplanetary bodies onto Earth compiled by Ceplecha. We attempted to model a cratering story of a typical cometary nucleus during its lifetime starting from its formation. According to numerical models of impacts into ice, the penetration depth varies from millimeters to several tens of meters. Models were computed for the size range of projectiles from 10 micron to 10 m, velocities from 10 m/s to 10 km/s, and densities from 1 to 8 g/ccm.
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)
The intergalactic propagation of ultrahigh energy cosmic ray nuclei
Energy Technology Data Exchange (ETDEWEB)
Hooper, Dan; /Fermilab; Sarkar, Subir; /Oxford U., Theor. Phys.; Taylor, Andrew M.; /Oxford U.
2006-08-01
We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).
Energy spectra of odd nuclei in the generalized model
Directory of Open Access Journals (Sweden)
I. O. Korzh
2015-04-01
Full Text Available Based on the generalized nuclear model, energy spectra of the odd nuclei of such elements as 25Mg, 41K, and 65Cu are determined, and the structure of wave functions of these nuclei in the excited and normal states is studied. High quality in determining the energy spectra is possible due to the accurate calculations of all elements of the energy matrix. It is demonstrated that the structure of the wave functions so determined provides the possibility to more accurately select the nuclear model and the method for calculating the nucleon cross-sections of the inelastic scattering of nucleons by odd nuclei.
New aspects of the neutron capture in light nuclei
Energy Technology Data Exchange (ETDEWEB)
Mengoni, A. [Institute of Physical and Chemical Research, Wako, Saitama (Japan)
1997-03-01
Several neutron capture cross sections of light nuclei (A {<=} 40) for neutron energies up to the MeV region have been recently calculated. Examples are (target nuclei): {sup 12}C, {sup 13}C, {sup 16}O and {sup 10}Be. The results of these calculations will be shown together with a comparison with the most recent experimental data. In the case of n + {sup 10}Be case, the cross section of the inverse process (Coulomb dissociation of {sup 11}Be) is considered and compared with the measurement. A discussion on the relevant nuclear structure information required for the evaluation of nuclear data of light nuclei is given. (author)
Deexcitation of nuclei formed near the instability temperature
International Nuclear Information System (INIS)
Rivet, M.F.; Borderie, B.; Gauvin, H.; Gardes, D.; Cabot, C.; Hanappe, F.; Peter, J.
1986-01-01
Fusion-like reactions induced on medium mass targets by 27 MeV per nucleon argon projectiles were studied. The properties of evaporation residues and binary fission fragments, both cold remnants of fusion nuclei, show that highly excited nuclei were produced, near the temperature of instability of nuclear matter. Fission-evaporation competition in the deexcitation of these nuclei is reflected in the ratio of fission and residue cross sections, which provides a way of studying the role of prefission evaporation and fission barriers in the deexcitation process
The role of quasiparticles in rotating transitional nuclei
International Nuclear Information System (INIS)
Frauendorf, Stefan
1984-01-01
The yrast sequency of nuclei rotating about the symmetry axis is classified in analogy to class I and II superconductors, where the quasiparticles play the role of the quantized flux in metals. The experimental spectra show a class I behaviour. The ω-dependence of the quasiparticle excitation energy in collectively rotating nuclei is used as evidence for magnitude of the pair correlations and the occurrence of triaxial shapes. A transition from triaxial to oblate shape explains the experimental spectra and E2-transition probabilities in the N=88-90 nuclei. (author)
Cluster radioactivity of Z=125 super heavy nuclei
International Nuclear Information System (INIS)
Manjunatha, H.C.; Seenappa, L.
2015-01-01
For atomic numbers larger than 121 cluster decay and spontaneous fission may compete with α decay. Hence there is a need to make reliable calculations for the cluster decay half-lives of superheavy nuclei to predict the possible isotopes super heavy nuclei. So, in the present work, we have studied the decay of clusters such as 8 Be, 10 Be, 12 C, 14 C, 16 C, 18 O, 20 O, 22 Ne, 24 Ne, 25 Ne, 26 Ne, 28 Mg, 30 Mg, 32 Si, 34 Si, 36 Si, 40 S, 48 Ca, 50 Ca and 52 Ti from the super heavy nuclei Z=125
Hot nuclei with high spin states in collisions between heavy nuclei
International Nuclear Information System (INIS)
Galin, J.
1991-01-01
In the first part of this contribution we have shown that pretty hot nuclei could be obtained in peripheral collisions of Kr+Au. The collisions considered in the chosen example give rise to a nucleus of Z=28 with a kinetic energy of 1600 MeV (i.e. a velocity close to 27 MeV/u to be compared with the 32 MeV/u of the beam). The excitation energy deposited in the non-detected target like-nucleus, deduced from the neutron multiplicity measurements, amounts to 700 MeV (T= 6 MeV). In the second part of the contribution one used the well known properties of fission, and particularly its sensitivity to spin, to show in a qualitative way that pretty high spin values are into play. A more quantitative analysis together with additional measurements are still needed in order to infer precise figures of spin. It can be noted that for the 29 MeV/u Pb+Au reaction 1 max amounts to 1700 ℎ. If we assume that the sticking or rolling conditions can be fulfilled for initial angular momenta of about 2/3 1 max , then a projectile-like (and its target partner) could acquire an intrinsic spin of about 160 ℎ. The behavior of a Pb-like nucleus brought in such an exotic state (T=6 MeV and J=160ℎ)) is certainly worth to be studied in detail. It is also worth recalling that, when obtained in peripheral collisions, the hot nuclei thus formed do not suffer much initial compression at variance with what happens in more central collisions. There is thus an interesting field to be explored of hot, high spin but uncompressed nuclei
Correlated basis functions theory of light nuclei. Pt. 2. Spectra of light nuclei
Energy Technology Data Exchange (ETDEWEB)
Guardiola, R.; Bosca, M.C.
1988-11-14
This work is a continuation of a previous one devoted to the study of ground-state energies of p-shell nuclei using the correlated basis functions theory. Here, the low-lying excited levels are computed and compared with experiment. This study has no free parameters, and everything is directly obtained from a realistic Reid V8 nucleon-nucleon interaction. As expected, we do not obtain quantitative agreement with the experimental levels. However, many of the qualitative characteristics of the spectrum emerge naturally.
Population of Nuclei Via 7Li-Induced Binary Reactions
Energy Technology Data Exchange (ETDEWEB)
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
2005-08-08
The authors have investigated the population of nuclei formed in binary reactions involving {sup 7}Li beams on targets of {sup 160}Gd and {sup 184}W. The {sup 7}Li + {sup 184}W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si {Delta}E-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.
New properties of giant resonances in highly excited nuclei
International Nuclear Information System (INIS)
Morsch, H.P.
1991-01-01
Studies on the giant dipole resonance in very hot nuclei investigated in heavy ion-induced particle-γ coincidence experiments are reviewed. A signature is found in the γ-decay of excited nuceli which shows direct decay of the giant dipole resonance. This provides a new dimension in giant resonance studies and the possibility to study the dependence of giant resonance energy, width and sum rule strength on excitation energy and rotation of the system. Further, the fact that the giant resonance splits in deformed nuclei provides a unique way to get information on the shape of hot nuclei. First results are obtained on the following questions: (i)What is the nuclear shape at high temperature (T≥2 MeV)? (ii)Is there a phase transition in the nuclear shape at T∼1.7 MeV? (iii)Does motional narrowing exist in hot nuclei? (author). 19 refs., 11 figs
The parton distributions in nuclei and in polarized nucleons
Energy Technology Data Exchange (ETDEWEB)
Close, F.E.
1988-01-01
The emerging information was reviewed on the way quark and anti-quark, and gluon distributions are modified in nuclei relative to free nucleons. Some implications of the recent data on polarized leptoproduction are discussed. 27 refs., 6 figs.
Structure of proton-rich nuclei of astrophysical interest
Energy Technology Data Exchange (ETDEWEB)
Roeckl, E. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany)
1998-06-01
Recent experimental data concerning proton-rich nuclei between A=20 and A=100 are presented and discussed with respect to their relevance to the astrophysical rp process and to the calibration of solar neutrino detectors. (orig.)
Superheavy nuclei from 48Ca-induced reactions
Oganessian, Yu. Ts.; Utyonkov, V. K.
2015-12-01
The discovery and investigation of the new region of superheavy nuclei at the DGFRS separator based on fusion reactions of 48Ca with 238U-249Cf target nuclei are reviewed. The production cross sections and summaries of the decay properties, including the results of the posterior experiments performed at the SHIP, BGS, and TASCA separators, as well as at the chemistry setups, are discussed and compared with the theoretical calculations and the systematic trends in the α-decay and spontaneous fission properties. The properties of the new nuclei, isotopes of elements 112-118, and their decay products demonstrate significant increases in the stability of the heaviest nuclei with increasing neutron number and closer approach to magic number N = 184.
Studies of pear-shaped nuclei using accelerated radioactive beams
Gaffney, L P; Scheck, M; Hayes, A B; Wenander, F; Albers, M; Bastin, B; Bauer, C; Blazhev, A; Bonig, S; Bree, N; Cederkall, J; Chupp, T; Cline, D; Cocolios, T E; Davinson, T; DeWitte, H; Diriken, J; Grahn, T; Herzan, A; Huyse, M; Jenkins, D G; Joss, D T; Kesteloot, N; Konki, J; Kowalczyk, M; Kroll, Th; Kwan, E; Lutter, R; Moschner, K; Napiorkowski, P; Pakarinen, J; Pfeiffer, M; Radeck, D; Reiter, P; Reynders, K; Rigby, S V; Robledo, L M; Rudigier, M; Sambi, S; Seidlitz, M; Siebeck, B; Stora, T; Thoele, P; Van Duppen, P; Vermeulen, M J; von Schmid, M; Voulot, D; Warr, N; Wimmer, K; Wrzosek-Lipska, K; Wu, C Y; Zielinska, M
2013-01-01
There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on and $^{224}$Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental...
Empirical realization of a critical point description in atomic nuclei.
Casten, R F; Zamfir, N V
2001-07-30
It is shown that (152)Sm and other N = 90 isotones are the first empirical manifestation of the newly predicted analytic description of nuclei at the critical point of a vibrator to axial rotor phase transition.
Pseudospin Symmetry as a Bridge between Hadrons and Nuclei
Directory of Open Access Journals (Sweden)
Joseph N. Ginocchio
2016-03-01
Full Text Available Atomic nuclei exhibit approximate pseudospin symmetry. We review the arguments that this symmetry is a relativistic symmetry. The condition for this symmetry is that the sum of the vector and scalar potentials in the Dirac Hamiltonian is a constant. We give the generators of pseudospin symmetry. We review some of the predictions that follow from the insight that pseudospin symmetry has relativistic origins . We show that approximate pseudospin symmetry in nuclei predicts approximate spin symmetry in anti-nucleon scattering from nuclei. Since QCD sum rules predict that the sum of the scalar and vector potentials is small, we discuss the quark origins of pseudospin symmetry in nuclei and spin symmetry in hadrons.
Comparing and contrasting nuclei and cold atomic gases
DEFF Research Database (Denmark)
Zinner, Nikolaj Thomas; Jensen, Aksel Stenholm
2013-01-01
The experimental revolution in ultracold atomic gas physics over the past decades has brought tremendous amounts of new insight to the world of degenerate quantum systems. Here we compare and contrast the developments of cold atomic gases with the physics of nuclei since many concepts, techniques......, and nomenclatures are common to both fields. However, nuclei are finite systems with interactions that are typically much more complicated than those of ultracold atomic gases. The similarities and differences must therefore be carefully addressed for a meaningful comparison and to facilitate fruitful......, interactions, and relevant length and energy scales of cold atoms and nuclei. Next we address some attempts in nuclear physics to transfer the concepts of condensates in nuclei that can in principle be built from bosonic alpha-particle constituents. We also consider Efimov physics, a prime example of nuclear...
On some common problems in particle physics and nuclei physics
International Nuclear Information System (INIS)
Vinh Mau, R.
1976-01-01
Results of recent studies on the use of a nuclear potential derived from the present knowledge in particle physics, in nuclei and systems composed by nucleon-antinucleon pairs, are presented and discussed
Deep Learning Nuclei Detection in Digitized Histology Images by Superpixels
Directory of Open Access Journals (Sweden)
Sudhir Sornapudi
2018-01-01
Full Text Available Background: Advances in image analysis and computational techniques have facilitated automatic detection of critical features in histopathology images. Detection of nuclei is critical for squamous epithelium cervical intraepithelial neoplasia (CIN classification into normal, CIN1, CIN2, and CIN3 grades. Methods: In this study, a deep learning (DL-based nuclei segmentation approach is investigated based on gathering localized information through the generation of superpixels using a simple linear iterative clustering algorithm and training with a convolutional neural network. Results: The proposed approach was evaluated on a dataset of 133 digitized histology images and achieved an overall nuclei detection (object-based accuracy of 95.97%, with demonstrated improvement over imaging-based and clustering-based benchmark techniques. Conclusions: The proposed DL-based nuclei segmentation Method with superpixel analysis has shown improved segmentation results in comparison to state-of-the-art methods.
Deep Learning Nuclei Detection in Digitized Histology Images by Superpixels.
Sornapudi, Sudhir; Stanley, Ronald Joe; Stoecker, William V; Almubarak, Haidar; Long, Rodney; Antani, Sameer; Thoma, George; Zuna, Rosemary; Frazier, Shelliane R
2018-01-01
Advances in image analysis and computational techniques have facilitated automatic detection of critical features in histopathology images. Detection of nuclei is critical for squamous epithelium cervical intraepithelial neoplasia (CIN) classification into normal, CIN1, CIN2, and CIN3 grades. In this study, a deep learning (DL)-based nuclei segmentation approach is investigated based on gathering localized information through the generation of superpixels using a simple linear iterative clustering algorithm and training with a convolutional neural network. The proposed approach was evaluated on a dataset of 133 digitized histology images and achieved an overall nuclei detection (object-based) accuracy of 95.97%, with demonstrated improvement over imaging-based and clustering-based benchmark techniques. The proposed DL-based nuclei segmentation Method with superpixel analysis has shown improved segmentation results in comparison to state-of-the-art methods.
Organic Aerosols as Cloud Condensation Nuclei
Hudson, J. G.
2002-05-01
The large organic component of the atmospheric aerosol contributes to both natural and anthropogenic cloud condensation nuclei (CCN). Moreover, some organic substances may reduce droplet surface tension (Facchini et al. 1999), while others may be partially soluble (Laaksonen et al. 1998), and others may inhibit water condensation. The interaction of organics with water need to be understood in order to better understand the indirect aerosol effect. Therefore, laboratory CCN spectral measurements of organic aerosols are presented. These are measurements of the critical supersaturation (Sc), the supersaturation needed to produce an activated cloud droplet, as a function of the size of the organic particles. Substances include sodium lauryl (dodecyl) sulfate, oxalic, adipic, pinonic, hexadecanedioic, glutaric, stearic, succinic, phthalic, and benzoic acids. These size-Sc relationships are compared with theoretical and measured size-Sc relationships of common inorganic compounds (e.g., NaCl, KI, ammonium and calcium sulfate). Unlike most inorganics some organics display variations in solubility per unit mass as a function of particle size. Those showing relatively greater solubility at smaller sizes may be attributable to surface tension reduction, which is greater for less water dilution, as is the case for smaller particles, which are less diluted at the critical sizes. This was the case for sodium dodecyl sulfate, which does reduce surface tension. Relatively greater solubility for larger particles may be caused by greater dissolution at the higher dilutions that occur with larger particles; this is partial solubility. Measurements are also presented of internal mixtures of various organic and inorganic substances. These measurements were done with two CCN spectrometers (Hudson 1989) operating simultaneously. These two instruments usually displayed similar results in spite of the fact that they have different flow rates and supersaturation profiles. The degree of