Assigning {gamma} deformation from fine structure in exotic nuclei
Ferreira, L. S.; Maglione, E.; Arumugam, P.
2011-10-28
The nonadiabatic quasiparticle model for triaxial shapes is used to perform calculations for decay of {sup 141}Ho, the only known odd-Z even-N deformed nucleus for which fine structure in proton emission from both ground and isomeric states has been observed. All experimental data corresponding to this unique case namely, the rotational spectra of parent and daughter nuclei, decay widths and branching ratios for ground and isomeric states, could be well explained with a strong triaxial deformation {gamma}{approx}20. The recent experimental observation of fine structure decay from the isomeric state, can be explained only with an assignment of I{sup {pi}} = 3/2{sup +} as the decaying state, in contradiction with the previous assignment, of I{sup {pi}} 1/2{sup +}, based on adiabatic calculations. This study reveals that proton emission measurements could be a precise tool to probe triaxial deformations and other structural properties of exotic nuclei beyond the proton dripline.
Galindo-Uribarri, Alfredo {nmn}
2010-01-01
Current experimental developments on the study of exotic nuclei far from the valley of stability are discussed. I start with general aspects related to the production of radioactive beams followed by the description of some of the experimental tools and specialized techniques for studies in reaction spectroscopy, nuclear structure research and nuclear applications with examples from selected topical areas with which I have been involved. I discuss some of the common challenges faced in Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beam (RIB) science.
Exotic modes of excitation in deformed neutron-rich nuclei
Yoshida, Kenichi
2011-05-06
Low-lying dipole excitation mode in neutron-rich Mg isotopes close to the drip line is investigated in the framework of the Hartree-Fock-Bogoliubov and the quasiparticle random-phase approximation employing the Skyrme and the pairing energy-density functionals. It is found that the low-lying dipole-strength distribution splits into the K{sup {pi}} = 0{sup -} and 1{sup -} components due to the nuclear deformation. The low-lying dipole strength increases as the neutron drip-line is approached.
2-D Hartee-Fock-Bogoliubov Calculations For Exotic Deformed Nuclei
NASA Astrophysics Data System (ADS)
Blazkiewicz, Artur; Oberacker, Volker E.; Umar, Sait A.; Teran, Edgar
2003-10-01
We solve the Hartree-Fock-Bogoliubov (HFB) equations in coordinate space; the computational method has been specifically designed to study ground state properties of nuclei near the neutron and proton drip lines teref1. The unique feature of our code is that it takes into account the strong coupling to high-energy continuum states, up to an equivalent single-particle energy of 60 MeV or higher. We solve the HFB equations for deformed, axially symmetric even-even nuclei in coordinate space on a 2-D lattice with Basis-Spline methods. For the p-h channel, the Skyrme (SLy4) effective N-N interaction is utilized, and for the p-p and h-h channel we use a delta interaction. Results teref2,ref3 are presented for binding energies, deformations, normal densities and pairing densities, Fermi levels, and pairing gaps. In particular, we calculate the properties of two light isotope chains up to the two-neutron dripline: oxygen (^22-28O) and sulfur (^40-52S). For some of the sulfur isotopes we found the "shape coexistence" what was also confirmed by RMF calculations of P. Ring and G.A. Lalazissis teref4. Furthermore, we study the strongly deformed heavy systems zirconium (^102,104Zr), cerium (^152Ce), and samarium (^158Sm).We are also planning to study other isotopes by running our new parallel MPI version of HFB code. Comparison with relativistic mean field theory and with experimental data is given whenever available. This work has been supported by the U.S. Department of Energy under grant No. DE-FG02-96ER40963 with Vanderbilt University. The numerical calculations were carried out on the IBM-RS/6000 SP supercomputer at NERSC in Berkeley and on our local "Beowulf" Vampire computer at Vanderbilt University. 99 ref1 Axially Symmetric Hartee-Fock-Bogoliubov calculations for nuclei near the drip lines,E. Teran, V.E. Oberacker and A.S. Umar, Phys. Rev. C 67, (June 2003) ref2 Half lives of isomeric states from SF of ^252Cf and large deformations in ^104Zr and ^158Sm, J.K. Hwang, A
NASA Astrophysics Data System (ADS)
Neff, Thomas; Feldmeier, Hans; Roth, Robert
2006-10-01
In the Fermionic Molecular Dynamics (FMD) model the nuclear many-body system is described using Slater determinants with Gaussian wave-packets as single-particle states. The flexibility of the FMD wave functions allows for a consistent description of shell model like structures, deformed states, cluster structures as well as halos. An effective interaction derived from the realistic Argonne V18 interaction using the Unitary Correlation Operator Method is used for all nuclei. Results for nuclei in the p-shell will be presented. Halo features are present in the Helium isotopes, cluster structures are studied in Beryllium and Carbon isotopes. The interplay between shell structure and cluster structures in the ground and the Hoyle state in ^12C will be discussed.
Relativistic Mean Field description of exotic nuclei
NASA Astrophysics Data System (ADS)
Gambhir, Y. K.
1994-03-01
The Relativistic Mean Field (RMF) approach which essentially is an extension of the original σ — ω model of Walecka, has been applied to exotic nuclei as an illustration. We consider nuclei near Z = 34 in the very interesting 2p-1f region. The calculated binding energies, root mean square radii, deformations and other observables are very satisfactory and are in accordance with the experiment (where available) and also with the available empirical studies. Large deformations and shape co-existence are obtained for several cases.
ERIC Educational Resources Information Center
Cerny, Joseph; Poskanzer, Arthur M.
1978-01-01
Among the light elements, nuclei with unequal numbers of protons and neutrons are highly unstable. Some survive just long enough to be detected and exhibit unusual regimes of radioactive decay. ( Autor/MA)
International Symposium on Exotic Nuclei
NASA Astrophysics Data System (ADS)
Penionzhkevich, Yu. E.; Cherepanov, E. A.
Methods of production of light exotic nuclei and study of their ptoperties -- Superheavy elements. Syhnthesis and properties -- Nuclear fission -- Nuclear reactions -- rare processes, decay and nuclear structure -- Experimental set-ups and future projects -- Radioactive beams. Production and research programmes -- Public relations.
NASA Astrophysics Data System (ADS)
Penionzhkevich, Yu. E.
2012-07-01
Recently the academic community has marked several anniversaries connected with discoveries that played a significant role in the development of astrophysical investigations. The year 2009 was proclaimed by the United Nations the International Year of Astronomy. This was associated with the 400th anniversary of Galileo Galilei's discovery of the optical telescope, which marked the beginning of regular research in the field of astronomy. An important contribution to not only the development of physics of the microcosm, but also to the understanding of processes occurring in the Universe, was the discovery of the atomic nucleus made by E. Rutherford 100 years ago. Since then the investigations in the fields of physics of particles and atomic nuclei have helped to understand many processes in the microcosm. Exactly 80 years ago, K. Yanski used a radio-telescope in order to receive the radiation from cosmic objects for the first time, and at the present time this research area of physics is the most efficient method for studying the properties of the Universe. Finally, the April 12, 1961 (50 years ago) launching of the first sputnik into space with a human being onboard, the Russian cosmonaut Yuri Gagarin, marked the beginning of exploration of the Universe with the direct participation of man. All these achievements considerably extended our ideas about the Universe. 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 nuclear-physics methods for studying cosmic objects and properties of the Universe. The results of
Exotic nuclei and nuclear forces
NASA Astrophysics Data System (ADS)
Otsuka, Takaharu
2013-01-01
I overview new aspects of the structure of exotic nuclei as compared to stable nuclei, focusing on several characteristic effects of nuclear forces. The shell structure of nuclei has been proposed by Mayer and Jensen, and has been considered to be kept valid basically for all nuclei, with well-known magic numbers, 2, 8, 20, 28, 50, …. Nuclear forces were shown, very recently, to change this paradigm. It will be presented that the evolution of shell structure occurs in various ways as more neutrons and/or protons are added, and I will present basic points of this shell evolution in terms of the monopole interaction of nuclear forces. I will discuss three types of nuclear forces. The first one is the tensor force. The tensor force is one of the most fundamental nuclear forces, but its first-order effect on the shell structure has been clarified only recently in studies on exotic nuclei. The tensor force can change the spin-orbit splitting depending on the occupation of specific orbits. This results in changes of the shell structure in many nuclei, and consequently some of Mayer-Jensen's magic numbers are lost and new ones emerge, in certain nuclei. This mechanism can be understood in an intuitive way, meaning that the effect is general and robust. The second type of nuclear forces is central force. I will show a general but unknown property of the central force in the shell-model Hamiltonian that can describe nuclear properties in a good agreement with experiment. I will then demonstrate how it can be incorporated into a simple model of the central force, and will discuss how this force works in the shell evolution. Actually, by combining this central force with the tensor force, one can understand and foresee how the same proton-neutron interaction drives the shell evolution, for examples such as Sn/Sb isotopes, N = 20 nuclei and Ni/Cu isotopes. The distribution of single-particle strength is discussed also in comparison to (e,e‧p) experiment on 48Ca. The shell
Reaction theories for exotic nuclei
Bonaccorso, Angela
2012-11-20
This contribution discusses two important dynamical effects in the scattering of exotic beams. The first part deals proton breakup. The Coulomb interactions between the core and the target and the proton and the target are treated to all orders, including also the full multipole expansion of the Coulomb potential. The dynamics of proton Coulomb breakup is compared to that of an equivalent neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism. With respect to nuclear breakup it is found that a proton behaves exactly as a neutron of larger binding energy. The extra 'effective energy' is due to the combined core-target Coulomb barrier. In Coulomb breakup we distinguish the effect of the core-target Coulomb potential (called recoil effect), with respect to which the proton behaves again as a more bound neutron, from the direct proton-target Coulomb potential. The latter gives cross sections about an order of magnitude larger than the recoil term. The two effects give rise to complicated interferences in the parallel momentum distributions. They are instead easily separable in the proton angular distributions which are therefore suggested as a very useful observable for future experimental studies. The second part has to do with the dynamics of one-neutron and one-proton removal from unstable nuclei with large asymmetry {Delta}S S{sub n}-S{sub p} in the separation energies and incident energies below 80 MeV/nucleon. Strong non-sudden effects are observed in the case of deeply-bound-nucleon removal. The corresponding parallel momentum distributions exhibit an abrupt cutoff at high momentum that corresponds to an energy threshold occurring when the incident energy per particle is of comparable magnitude as the nucleon separation energy.
Study of Nuclear Moments on Exotic Nuclei
Ishihara, Masayasu
2010-04-30
Nuclear moments have been measured for a few tens of light unstable nuclei located very far from the line of stability using beta-NMR methods and spin-polarized RI beams. The obtained values of those moments provided indispensable information to reveal/disentangle unique properties of exotic nuclei.
Exotic nuclei with open heavy flavor mesons
Yasui, Shigehiro; Sudoh, Kazutaka
2009-08-01
We propose stable exotic nuclei bound with D and B mesons with respect to heavy quark symmetry. We indicate that an approximate degeneracy of D(B) and D*(B*) mesons plays an important role, and discuss the stability of DN and BN bound states. We find the binding energies 1.4 MeV and 9.4 MeV for each state in the J{sup P}=1/2{sup -} with the I=0 channel. We discuss also possible existence of exotic nuclei DNN and BNN.
Transfer involving deformed nuclei
Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.
1985-03-01
Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs.
Direct Reactions with Exotic Nuclei
Baur, G.; Typel, S.
2005-10-14
We discuss recent work on Coulomb dissociation and an effective-range theory of low-lying electromagnetic strength of halo nuclei. We propose to study Coulomb dissociation of a halo nucleus bound by a zero-range potential as a homework problem. We study the transition from stripping to bound and unbound states and point out in this context that the Trojan-Horse method is a suitable tool to investigate subthreshold resonances.
Dynamical effects in fusion with exotic nuclei
NASA Astrophysics Data System (ADS)
Vo-Phuoc, K.; Simenel, C.; Simpson, E. C.
2016-08-01
Background: Reactions with stable beams have demonstrated strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments. Purpose: To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei. Method: Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in -54Ca40+116Sn reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations. Results: The development of a neutron skin in exotic calcium isotopes strongly lowers the bare potential barrier. However, this static effect is not apparent when dynamical effects are included. On the contrary, a fusion hindrance is observed in TDHF calculations with the most neutron-rich calcium isotopes which cannot be explained by vibrational couplings. Transfer reactions are also important in these systems due to charge equilibration processes. Conclusions: Despite its impact on the bare potential, the neutron skin is not seen as playing an important role in the fusion dynamics. However, the charge transfer with exotic projectiles could lead to an increase of the Coulomb repulsion between the fragments, suppressing fusion. The effects of transfer and dissipative mechanisms on fusion with exotic nuclei deserve further studies.
Perspectives of Physics of Exotic Nuclei Beyond the Shell Evolution
NASA Astrophysics Data System (ADS)
Otsuka, Takaharu
2015-11-01
I present one of the possible paradigm shifts with exotic nuclei. This is the shell evolution due to nuclear forces, such as tensor, central and three-nucleon forces. I shall present major points with the N=34 magic number confirmed in 54Ca by RIBF of RIKEN very recently, after the theoretical prediction made in 2001. The shell evolution has been generalized to phenomena caused by massive particle-hole excitations, being referred to as Type II Shell Evolution. This can be found in 68,70Ni. In particular, the shape coexistence of spherical, oblate and prolate shapes is suggested theoretically. Thus, the perspectives of physics with exotic nuclei is being expanded further from single-particle aspects to shapes/deformation, changing the landscape of nuclear structure.
Physics of Exotic Nuclei at RIBF
NASA Astrophysics Data System (ADS)
Sakurai, Hiroyoshi
2014-09-01
``Exotic nuclei'' far from the stability line are unique objects of many-body quantum system, where ratios of neutron number to proton number are much larger or much smaller than those of nuclei found in nature. Their exotic properties and phenomena emerge from their large isospin asymmetry, and even affect scenarios of nucleosynthesis in the universe. Efforts have been made to produce and investigate such exotic nuclei at the accelerator facilities in the world. One of the facilities, the Radioactive Isotope Beam Factory (RIBF) facility at RIKEN, Japan has delivered intense radioactive isotope (RI) beams since 2007. In US, the Facility for Rare Isotope Beams is being constructed to start around 2020. To access nuclei far from the stability line, especially neutron-rich nuclei, the RIBF facility is highly optimized for inflight production of fission fragments via a U beam. The Super-conducting Ring Cyclotron delivers a 345 MeV/u U beam. The U nuclide is converted at a target to fission fragments. An inflight separator BigRIPS was designed to collect about 50% of fission fragments produced at the target and separate nuclei of interest. The RI beams produced at BigRIPS are then delivered to several experimental devices. Large-scale international collaborations have been formed at three spectrometers to conduct unique programs for the investigation of decay properties single particle orbits, collective motions, nucleon correlation, and the equation-of-state of asymmetric nuclear matter. Nuclear binding energy will be measured at a newly constructed ring for the r-process path, and charge distribution of exotic nuclei will be examined at a unique setup of an RI target section in an electron storage ring. Ultra slow RI beams available at a gas catcher system will be utilized for table-top and high precision measurements. In this talk, I would give a facility overview of RIBF, and introduce objectives at RIBF. Special emphasis would be given to selected recent highlights
Casten, R.F.; Warner, D.D.
1982-01-01
The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for /sup 168/Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong ..beta.. ..-->.. ..gamma.. transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the ..beta.. ..-->.. ..gamma.. transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ..delta..K=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics.
Neutron scattering on deformed nuclei
NASA Astrophysics Data System (ADS)
Hansen, L. F.; Haight, R. C.; Pohl, B. A.; Wong, C.; Lagrange, Ch.
1985-01-01
Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9Be, C, 181Ta, 232Th, 238U, and 239Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune, and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonably good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP.
Single particle versus collectivity, shapes of exotic nuclei
NASA Astrophysics Data System (ADS)
Jungclaus, Andrea
2016-03-01
In this article some selected topics of nuclear structure research will be discussed as illustration of the progress reached in this field during the last thirty years. These examples evidence the improvement of our understanding of the atomic nucleus reached on the basis of countless experiments, performed to study both exotic nuclei (nuclei far-off the valley of stability) as well as nuclei under exotic conditions (high excitation energy/temperature or large angular momentum/rotational frequency), using stable and radioactive ion beams. The experimental progress, in parallel to the advancement of modern theoretical descriptions, led us to a much richer view of this fundamental many-body system.
JUSTIPEN: Japan US Theory Institute for Physics with Exotic Nuclei
Papenbrock, Thomas
2014-05-16
The grant “JUSTIPEN: Japan US Theory Institute for Physics with Exotic Nuclei ” (DOE DE‐FG02‐06ER41407) ran from 02/01/2006 thru 12/31/2013. JUSTIPEN is a venue for international collaboration between U.S.‐based and Japanese scientists who share an interest in theory of rare isotopes. Since its inception JUSTIPEN has supported many visitors, fostered collaborations between physicists in the U.S. and Japan, and enabled them to deepen our understanding of exotic nuclei and their role in cosmos.
Exotic rotations and triaxiality in Nd nuclei
NASA Astrophysics Data System (ADS)
Petrache, C. M.
2015-11-01
We have recently studied the Nd nuclei up to very high spins and identified a multitude of bands which are interpreted as the manifestation of a nucleus with stable triaxial shape, presenting various types of collective motion: tilted axis and principal axis rotation, wobbling motion, chiral bands. Seniority isomers built on nearly spherical shapes up to very high spins, surrounded by coexisting triaxial bands, have also been observed. The new results obtained from the systematics of the high-spin bands of Nd nuclei are discussed.
Towards a Deeper Understanding of the Nucleus with Exotic Nuclei
NASA Astrophysics Data System (ADS)
Ormand, Erich
2006-10-01
Despite more than fifty years of study, many questions about now nuclei are put together remain. While nuclei near the valley of stability have provided a wealth of information, they are not sufficient to provide us with a comprehensive and unified description of the nucleus. Especially lacking is an accurate picture of those exotic species that are the basis of cosmic alchemy. The missing pieces in the puzzle can be filled in with a determined experimental and theoretical effort focusing on nuclei lying far from the valley of stability. Here, I will outline the intellectual challenges that can be addressed by proposed exotic-beam facilities, and how new experimental data will quide and refine theoretical descriptions of the nucleus.
The surface geometry of exotic nuclei
Carlson, B. V.; Baldini-Neto, E.; Hirata, D.; Peru-Desenfants, S.; Berger, J.-F.; Chamon, L. C.
2007-02-12
We analyze the surface geometry of the spherical even-even Ca, Ni, Sn and Pb nuclei using two approaches: The relativistic Dirac-Hartree-Bogoliubov one with several parameter sets and the non-relativistic Hartree-Fock-Bogoliubov one with the Gogny force. The proton and neutron density distributions are fitted to two-parameter Fermi density distributions to obtain the half-density radii and diffuseness parameters. Those parameters allow us to determine the nature of the neutron skins predicted by the models. The calculations are compared with existing experimental data.
Fusion and reactions of exotic nuclei
NASA Astrophysics Data System (ADS)
Martel, I.; Aguilera, E. F.; Acosta, L.; Sánchez-Benítez, A. M.; Wolski, R.
2011-10-01
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.
Reactions and structure of exotic nuclei
Esbensen, H.
1993-08-01
Radioactive beam experiments have made it possible to study the structure of light neutron rich nuclei. A characteristic feature is a large dipole strength near threshold. An excellent example is the loosely bound nucleus ``Li for which Coulomb dissociation plays a dominant role in breakup reactions on a high Z target. I will describe a three-body model and apply it to calculate the dipole response of {sup 11}Li and the momentum distributions for the three-body breakup reaction: {sup 11}Li {yields} {sup 9}Li+n+n, and comparisons will be made to recent three-body coincidence measurements.
Clusterization and quadrupole deformation in nuclei
Cseh, J.; Algora, A.; Antonenko, N. V.; Jolos, R. V.; Scheid, W.; Darai, J.; Hess, P. O.
2006-04-26
We study the interrelation of the clusterization and quadrupole deformation of atomic nuclei, by applying cluster models. Both the energetic stability and the exclusion principle is investigated. Special attention is paid to the relative orientations of deformed clusters.
Exotic modes of excitation in proton rich nuclei
Paar, N.
2011-11-30
The framework of relativistic energy density functional has been applied in description of excitation phenomena in nuclei close to the proton drip line. In particular, low-lying dipole excitations have been studied using relativistic quasiparticle random phase approximation, based on effective Lagrangians with density dependent meson nucleon couplings. In the isovector dipole channel, the occurrence of pronounced low-lying dipole peaks is predicted, corresponding to the proton pygmy dipole resonance. Since this exotic mode still awaits its experimental confirmation, systematic calculations have been conducted within a pool of neutron deficient nuclei, in order to identify the best possible candidates for measurements.
New results on the structure of exotic nuclei
NASA Astrophysics Data System (ADS)
Sakurai, Hiroyoshi
2015-04-01
`Exotic nuclei' far from the stability line are unique objects of many-body quantum system, where ratios of neutron number to proton number are much larger or much smaller than those of nuclei found in nature. Their exotic properties and phenomena emerge from their large isospin asymmetry, and even affect scenarios of nucleosynthesis in universe. One of the exotic emergences is shell evolution. The magic numbers of stable nuclei are known; 2, 8, 20, 28, 50, 82 and 126. However the numbers 8, 20 and 28 have been found no more magic in a neutron-rich region, and new magic numbers such as 6, 16, 32 and 34 have been discovered. To access nuclei far from the stability line, especially neutron-rich nuclei, a large heavy-ion accelerator facility `Radioactive Isotope Beam Factory (RIBF)' was constructed at RIKEN, Japan in 2007. The facility is highly optimized for inflight production of fission fragments via a U beam. The accelerator complex delivers an intense 345 MeV/u U beam. The U nuclide is converted at a target to fission fragments. The fragments of interest are collected and separated at an inflight separator, and are delivered to several experimental devices. The shell evolution programs at RIBF have been conducted with two methods; in-beam gamma spectroscopy and decay spectroscopy. A standard setup of in-beam gamma spectroscopy is combination of a NaI gamma detector array `DALI2' and a beam line spectrometer `ZeroDegree Spectrometer (ZDS)'. Coincidence measurements of de-excitation gamma rays at DALI2 and of reaction products at ZDS make it possible to select reaction channels event-by-event and to observe excited states of exotic nuclei in a specific reaction channel. Recently, a French-made thick liquid hydrogen target system `MINOS' has been introduced to access more neutron-rich nuclei. Isomer and beta-delayed gamma spectroscopy is organized with a Euroball germanium cluster array system `EURICA' and an active silicon stopper In this talk, I would like to
Are the nuclei beyond 132Sn very exotic?
NASA Astrophysics Data System (ADS)
Lozeva, R.; Naïdja, H.; Nowacki, F.; Odahara, A.; Moon, C.-B.; NP1112-RIBF87 collaboration
2016-06-01
The term exotic nucleus is used for nuclei that have different from normal behavior. However, it turns out that the term normal is valid only for nuclei close to stability and more particularly for regions close to double-shell closures. As long as one drives away in the neutron-rich nuclei, especially at intermediate mass number, interplay between normal single-particle and many collective particle-hole excitations compete. In some cases with the addition of neutrons, these may turn to evolve as a skin, acting against the core nucleus that may also influence its shell evolution. Knowledge of these nuclear ingredients is especially interesting beyond the doubly-magic 132Sn, however a little is known on how the excitations modes develop with the addition of both protons and neutrons. Especially for the Sb nuclei, where one gradually increases these valence particles, the orbital evolution and its impact on exoticness is very intriguing. Experimental studies were conducted on several such isotopes using isomer and, β-decay spectroscopy at RIBF within EURICA. In particular, new data on 140Sb and 136Sb are examined and investigated in the framework of shell model calculations.
Structure of exotic nuclei by large-scale shell model calculations
Utsuno, Yutaka; Otsuka, Takaharu; Mizusaki, Takahiro; Honma, Michio
2006-11-02
An extensive large-scale shell-model study is conducted for unstable nuclei around N = 20 and N = 28, aiming to investigate how the shell structure evolves from stable to unstable nuclei and affects the nuclear structure. The structure around N = 20 including the disappearance of the magic number is reproduced systematically, exemplified in the systematics of the electromagnetic moments in the Na isotope chain. As a key ingredient dominating the structure/shell evolution in the exotic nuclei from a general viewpoint, we pay attention to the tensor force. Including a proper strength of the tensor force in the effective interaction, we successfully reproduce the proton shell evolution ranging from N = 20 to 28 without any arbitrary modifications in the interaction and predict the ground state of 42Si to contain a large deformed component.
PREFACE: Structure of Exotic Nuclei and Nuclear Forces
NASA Astrophysics Data System (ADS)
Honma, Michio; Otsuka, Takaharu; Aoi, Nori
2006-11-01
The International Symposium on `Structure of Exotic Nuclei and Nuclear Forces' was held at The Koshiba Hall, University of Tokyo, on 9 - 12 March 2006. This symposium was organized as an activity of the Grant-in-Aid for the specially promoted area `Monte Carlo Shell Model' from the Ministry of Education, Science, Sports and Culture (MEXT) of Japan. The symposium was sponsored by the Center for Nuclear Study (CNS) and by RIKEN. The purpose of the symposium was to discuss theoretical and experimental developments in the study of the structure of exotic nuclei and its relationship with nuclear forces. There has been much progress recently in our understanding of what the structure of exotic nuclei is and how it can be linked to nuclear forces, with emerging intriguing perspectives. The following subjects were covered in this symposium
Shell closures, loosely bound structures, and halos in exotic nuclei
Saxena, G.; Singh, D.
2013-04-15
Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.
Clusterization and Deformation in Heavy Nuclei
Algora, A.; Cseh, J.; Darai, J.; Hess, P.O.; Antonenko, N.V.; Jolos, R.V.; Scheid, W.
2005-11-21
The deformation-dependence of clusterization in heavy nuclei is investigated. In particular, allowed and forbidden cluster-configurations are determined for the ground, superdeformed, and hyperdeformed states of some nuclei, based on a microscopic (effective SU(3)) selection rule. The stability of the different cluster configurations from the viewpoint of the binding energy and the dinuclear system model (DNS) is also investigated.
Structure properties of medium and heavy exotic nuclei
NASA Astrophysics Data System (ADS)
Gaidarov, M. K.
2012-09-01
Investigations of important characteristics of the structure of nuclei near drip-lines in coordinate and momentum space have been performed. The charge form factors, charge and matter densities and the corresponding rms radii for even-even isotopes of Ni, Kr, and Sn are calculated in the framework of deformed self-consistent mean field Skyrme DDHF+BCS method. The resulting charge radii and neutron skin thicknesses of these nuclei are compared with available experimental data, as well as with other theoretical predictions. The formation of a neutron skin is analyzed in terms of various definitions. Its correlation with the nuclear symmetry energy is studied within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The nucleon momentum distributions for the same isotopic chains of neutron-rich nuclei are studied in the framework of the same mean-field method, as well as of theoretical correlation methods based on light-front dynamics and local density approximation. The isotopic sensitivities of the calculated neutron and proton momentum distributions are investigated together with the effects of nucleon correlations and deformation of nuclei.
Elastic scattering, fusion, and breakup of light exotic nuclei
NASA Astrophysics Data System (ADS)
Kolata, J. J.; Guimarães, V.; Aguilera, E. F.
2016-05-01
The present status of fusion reactions involving light ( A < 20) radioactive projectiles at energies around the Coulomb barrier ( E < 10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron- and proton-rich systems. Possible physical explanations for the observed differences are also reviewed.
Exotic Lepton Flavour Violating Processes in the Presence of Nuclei
NASA Astrophysics Data System (ADS)
Papoulias, D. K.; Kosmas, T. S.
2013-02-01
The discovery of neutrino oscillations indicates the existence of massive neutrinos in contrast to the massless neutrinos predicted by the Standard Model. One of the simplest extensions of the SM obtained by adding a heavy right-handed neutrino singlet, NR, per neutrino generation is the Seesaw mechanism. Within the context of this mechanism, flavour changing neutral current neutrino-nucleus reactions of the type are predicted to occur. In this contribution, motivated by the extensive studies (theoretical and experimental) of the LFV in ν- → e- conversion in nuclei, we investigate FCNC in neutrino-nucleus reactions. From a nuclear theory point of view, the Donnelly-Walecka model for cross sections calculations is employed. To this purpose, the single-particle transition matrix elements are evaluated from a Mathematica code developed in this work. Neutrino-nucleus reactions have important impact in Astrophysics and hence a detailed study of such exotic processes is of significant importance.
Three-Body Forces and Neutron-Rich Exotic Nuclei
NASA Astrophysics Data System (ADS)
Otsuka, Takaharu; Suzuki, Toshio
2013-08-01
Physics of three-body forces in connection to exotic nuclei will be discussed. Three-nucleon forces (3NF), especially Fujita-Miyazawa 3NF, are shown to be the key for the solution to the long-standing problem of oxygen drip line, which deviates from basic trend towards the stability line. Three-body forces produce repulsive modifications to effective interaction between valence neutrons, and make the ground states less bound. The oxygen drip line is then located at the right place. The relation to the neutron matter is presented. Applications to Ca isotopes will be presented. The shell evolution due to the 3NF depicts the raising of single-particle energies and the widening of splitting among the orbits. This is in contrast to the so-called shell quenching. The 2+ levels are calculated for Ca isotopes, suggesting about the same sub-magic structure for N = 32 and 34.
{alpha} Decay of Deformed Actinide Nuclei
Stewart, T.L.; Kermode, M.W.; Beachey, D.J.; Rowley, N.; Grant, I.S.; Kruppa, A.T.
1996-07-01
{alpha} decay through a deformed potential barrier produces significant mixing of angular momenta when mapped from the nuclear interior to the outside. Using experimental branching ratios and either semiclassical or coupled-channels transmission matrices, we have found that there is a set of internal amplitudes which is essentially constant for all even-even actinide nuclei. These same amplitudes also give good results for the known anisotropic {alpha}-particle emission of the favored decays of odd nuclei in the same mass region. {copyright} {ital 1996 The American Physical Society.}
Evolution of surface deformations of weakly bound nuclei in the continuum
NASA Astrophysics Data System (ADS)
Pei, J. C.; Zhang, Y. N.; Xu, F. R.
2013-05-01
We study weakly bound deformed nuclei based on the coordinate-space Skyrme Hartree-Fock-Bogoliubov (HFB) approach, in which a large box is employed for treating the continuum and large spatial extensions. When the limit of the core-halo deformation decoupling is approached, calculations found an exotic “egg”-like structure consisting of a spherical core plus a prolate halo in 38Ne, in which the near-threshold nonresonant continuum plays an essential role. Generally the halo probability and the decoupling effect in heavy nuclei can be hindered by high level densities around Fermi surfaces. However, deformed halos in medium-mass nuclei are possible as the negative-parity levels are sparse, e.g., in 110Ge. The deformation decoupling has also been demonstrated in pairing density distributions.
NASA Astrophysics Data System (ADS)
Nakamura, T.; Kondo, Y.
2016-06-01
Large acceptance spectrometers at in-flight RI separators have played significant roles in investigating the structure of exotic nuclei. Such spectrometers are in particular useful for probing unbound states of exotic nuclei, using invariant mass spectroscopy with reactions at intermediate and high energies. We discuss here the key characteristic features of such spectrometers, by introducing the recently commissioned SAMURAI facility at the RIBF, RIKEN. We also investigate the issue of cross talk in the detection of multiple neutrons, which has become crucial for exploring further unbound states and nuclei beyond the neutron drip line. Finally we discuss future perspectives for large acceptance spectrometers at the new-generation RI-beam facilities.
Effective field theory for deformed atomic nuclei
NASA Astrophysics Data System (ADS)
Papenbrock, T.; Weidenmüller, H. A.
2016-05-01
We present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. For rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.
Effective field theory for deformed atomic nuclei
Papenbrock, Thomas F.; Weidenmüller, H. A.
2016-04-13
In this paper, we present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. Finally, for rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.
Super-Heavy Element and Other Exotic Nuclei Research at LLNL
NASA Astrophysics Data System (ADS)
Stoyer, M. A.
2015-11-01
The experimental nuclear physics group at LLNL is actively investigating exotic nuclei in a variety of regions of the chart of nuclides - from light nuclei to super-heavy elements. The experimental nuclear physics effort at LLNL is centered on investigating nuclei at the extremes--in particular, extremes of spin, isospin, neutron richness, excitation energy, decay and detectability, mass, and stability. This talk will focus on recent heavy and super-heavy element experiments including nuclear structure investigations of the heaviest nuclei. Other areas of research, including radioactive ion beam experiments, trapping experiments, nuclear decay spectroscopy experiments, and rare decay searches, will be discussed as time permits. Recent experimental results on studies of exotic nuclei by scientists at LLNL will be presented.
QRPA Calculations for Spherical and Deformed Nuclei With the Gogny Force
Peru, S.
2009-08-26
Fully consistent axially-symmetric-deformed Quasi-particle Random Phase Approximation (QRPA) calculations have been performed with the D1S Gogny force. Dipole responses have been calculated in Ne isotopes to study the existence of soft dipole modes in exotic nuclei. A comparison between QRPA and generator coordinate method with Gaussian overlap approximation results is done for low lying 2{sup +} states in N = 16 isotones and Ni isotopes.
M1 excitation scheme in deformed nuclei
NASA Astrophysics Data System (ADS)
Otsuka, Takaharu; Morrison, Iain
1991-10-01
We present the M1 excitation scheme in even-even deformed nuclei from the sum-rule viewpoint based on the Nilsson+BCS approach. The sum-rule states are introduced for the Scissors, spin and spin-flip modes. The functional form of the B(M1) sum rule of the Scissors mode is obtained, and its actual value is shown to be 4˜6(μN2). The spin excitation B(M1) is 10˜15(μN2) including the spin-flip transitions. The total B(M1) is 15˜20(μN2). The effect of the SD and SDG pair truncation is studied to test IBM-2 for M1 excitations. The SDG truncation reproduces very well the calculation without truncation. The SD truncation reproduces the orbital excitation, whereas yields some deviations for the spin excitation.
Precision lifetime measurements of exotic nuclei based on Doppler-shift techniques
Iwasaki, Hironori
2013-04-19
A recent progress in precision lifetime measurements of exotic nuclei at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University is presented. The Recoil Distance Doppler-shift (RDDS) technique has been applied to nuclear reactions involving intermediate-energy rare isotope (RI) beams, to determine absolute transition strengths between nuclear states model independently from level lifetimes of interest. As such an example, recent lifetime measurements of the first 2{sup +} states in the neutron-rich {sup 62,64,66}Fe isotopes at and around N=40 are introduced. The experiment was performed at the Coupled Cyclotron Facility at NSCL using a unique combination of several experimental instruments; the Segmented Germanium Array (SeGA), the plunger device, and the S800 spectrograph. The reduced E2 transition probabilities B(E2) are determined directly from the measured lifetimes. The observed trend of B(E2) clearly demonstrates that an enhanced collectivity persists in {sup 66}Fe despite the harmonic-oscillator magic number N=40. The present results are also discussed in comparison with the large-scale shell model calculations, pointing to a possible extension of the deformation region beyond N=40.
Pygmy Dipole Strength and Neutron Skins in Exotic Nuclei
NASA Astrophysics Data System (ADS)
Klimkiewicz, A.; Paar, N.; Adrich, P.; Fallot, M.; Boretzky, K.; Aumann, T.; Cortina-Gil, D.; Pramanik, U. Datta; Elze, Th. W.; Emling, H.; Geissel, H.; Hellström, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Nociforo, C.; Palit, R.; Simon, H.; Surówka, G.; Sümmerer, K.; Vretenar, D.; Waluś, W.
2008-05-01
Dipole strength distributions were determined for the neutron-rich nuclei 129-132Sn and 133,134Sb from electromagnetic excitation in an experiment using the FRS-LAND setup. For all nuclei, a sizeable fraction of ``pygmy'' dipole strength at excitation energies well below the giant dipole resonance was observed. The integrated low-lying dipole strength of the nuclei with low neutron separation energies can be compared to results for stable nuclei (e.g. N = 82 isotopes) determined for the energy regime of 5-9 MeV. A clear increase of the dipole strength with increasing asymmetry of the nuclei is observed. Comparing the ratio of the low-lying dipole over the giant dipole strength to recent relativistic mean field calculations, values for the parameters a4 and p0 of the symmetry energy and for the neutron skin thickness are derived. Averaged over 130Sn and 132Sn we extract a4 = 31.8+/-1.3 MeV and p0 = 2.2+/-0.5 MeV/fm3. The neutron skin sizes are determined to Rn-Rp = 0.23+/-0.03 fm and 0.24+/-0.03 fm for 130Sn and 132Sn, respectively. For 208Pb a neutron skin thickness of Rn-Rp = 0.18+/-0.035 fm follows, when applying the same method and using earlier published experimental findings on the dipole strength.
Description of Exotic Nuclei with the Interacting Boson Model
Boeyuekata, M.; Van Isacker, P.; Uluer, I.
2008-11-11
Even--even nuclei in the A{approx}100 mass region are investigated within the framework of the interacting boson model-1 (IBM-1). The study includes energy spectra and electric quadrupole transition properties of zirconium, molybdenum, ruthenium and palladium isotopes with neutron number N{>=}54. A global parametrization of the IBM-1 hamiltonian is found leading to a description of 301 collective levels in 30 nuclei with a root-mean-square deviation from the observed level energies of 119 keV. The geometric character of the nuclei can be visualized by plotting the potential energy surface V({beta},{gamma}) obtained from the IBM-1 hamiltonian in the classical limit. The parametrization established on the basis of known elements is then used to predict properties of the unknown, neutron-rich isotopes {sup 106}Zr, {sup 112}Mo, {sup 116}Ru and {sup 120}Pd.
Halos and rainbows: The elastic scattering of light exotic nuclei
Satchler, G.R.; Hussein, M.H.
1993-10-01
The scattering of an exotic light nucleus with a halo is compared with that of a normal nucleus. Four, sometimes opposing effects arising from the halo are identified. Semiclassical expressions are derived which embody these effects. The cases of {sup 11}Li and {sup 11}C scattering from {sup 12}C at E/A = 60 MeV are compared. We conclude that the {sup 11}Li differential cross sections are probably smaller than those for {sup 11}C, in agreement with recent analyses of the measurements.
Folding model description of reactions with exotic nuclei
Ibraheem, Awad A.; Hassanain, M. A.; Mokhtar, S. R.; Zaki, M. A.; Mahmoud, Zakaria M. M.; Farid, M. El-Azab
2012-08-15
Microscopic folding calculations based upon the effective M3Y nucleon-nucleon interaction and the nuclearmatter densities of the interacting nuclei have been carried out to explain recently measured experimental data of the {sup 6}He+{sup 120}Sn elastic scattering cross section at four different laboratory energies near the Coulomb barrier. The extracted reaction cross sections are also considered.
Ab Initio Calculations Of Nuclear Reactions And Exotic Nuclei
Quaglioni, S.
2014-05-05
Our ultimate goal is to develop a fundamental theory and efficient computational tools to describe dynamic processes between nuclei and to use such tools toward supporting several DOE milestones by: 1) performing predictive calculations of difficult-to-measure landmark reactions for nuclear astrophysics, such as those driving the neutrino signature of our sun; 2) improving our understanding of the structure of nuclei near the neutron drip line, which will be the focus of the DOE’s Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University; but also 3) helping to reveal the true nature of the nuclear force. Furthermore, these theoretical developments will support plasma diagnostic efforts at facilities dedicated to the development of terrestrial fusion energy.
Probing the Evolution of the Shell Structures in Exotic Nuclei
De Angelis, Giacomo
2008-11-11
Magic numbers are a key feature in finite Fermion systems since they are strongly related to the underlying mean field. The size of the shell gaps and their evolution far from stability can be linked to the shape and symmetry of the nuclear mean field. Moreover the study of nuclei with large neutron/proton ratio allow to probe the density dependence of the effective interaction. Changes of the nuclear density and size in nuclei with increasing N/Z ratios are expected to lead to different nuclear symmetries and excitations. In this contribution I will discuss some selected examples which show the big potential of stable beams and of binary reactions for the study of the properties of the neutron-rich nuclear many body systems.
Light Nuclei Studied with Nucleon Transfer Reactions Using Exotic Beams
Wuosmaa, A. H.; Rehm, K. E.; Greene, J. P.; Henderson, D. J.; Janssens, R. V. F.; Jiang, C. L.; Moore, E. F.; Pardo, R. C.; Peterson, D.; Pieper, S. C.; Savard, G.; Schiffer, J. P.; Sinha, S.; Tang, X.; Wiringa, R. B.; Jisonna, L.; Segel, R. E.; Paul, M.
2006-04-26
Single-neutron transfer with the (d,p) reaction in inverse kinematics has been used to study the properties of the light nuclei 9Li and 7He. The results for 9Li and 7He are compared to the predictions of ab-initio models of nuclear structure. Different possibilities for excited states in 7He are discussed in the context of other recent experimental studies of 7He.
Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V. Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.
2015-05-15
In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the {sup 6}He, {sup 8}He, {sup 11}Li, and {sup 14}Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the {sup 8}Li, {sup 9}Li, and {sup 12}Be nuclei.
NASA Astrophysics Data System (ADS)
Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V.; Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.
2015-05-01
In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the 6He, 8He, 11Li, and 14Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the 8Li, 9Li, and 12Be nuclei.
NASA Astrophysics Data System (ADS)
Nishiuchi, M.; Sakaki, H.; Esirkepov, T. Zh.; Nishio, K.; Pikuz, T. A.; Faenov, A. Ya.; Skobelev, I. Yu.; Orlandi, R.; Pirozhkov, A. S.; Sagisaka, A.; Ogura, K.; Kanasaki, M.; Kiriyama, H.; Fukuda, Y.; Koura, H.; Kando, M.; Yamauchi, T.; Watanabe, Y.; Bulanov, S. V.; Kondo, K.; Imai, K.; Nagamiya, S.
2016-04-01
A combination of a petawatt laser and nuclear physics techniques can crucially facilitate the measurement of exotic nuclei properties. With numerical simulations and laser-driven experiments we show prospects for the Laser-driven Exotic Nuclei extraction-acceleration method proposed in [M. Nishiuchi et al., Phys, Plasmas 22, 033107 (2015)]: a femtosecond petawatt laser, irradiating a target bombarded by an external ion beam, extracts from the target and accelerates to few GeV highly charged short-lived heavy exotic nuclei created in the target via nuclear reactions.
Toward a Fundamental Understanding of Nuclear Reactions and Exotic Nuclei
NASA Astrophysics Data System (ADS)
Quaglioni, Sofia; Hupin, Guillaume; Langhammer, Joachim; Romero-Redondo, Carolina; Schuster, Micah D.; Johnson, Calvin W.; Navrátil, Petr; Roth, Robert
Nuclear systems near the drip lines offer an exciting opportunity to advance our understanding of the interactions among nucleons, which has so far been mostly based on the study of stable nuclei. However, this is not a goal devoid of challenges. From a theoretical standpoint, it requires the capability to address within an ab initio framework not only bound, but also resonant and scattering states, all of which can be strongly coupled. In recent years, significant progress has been made in ab initio nuclear structure and reaction calculations based on input from Quantum Chromodynamics employing Hamiltonians constructed within chiral effective field theory. In this contribution, we present a brief overview of one of such methods, the ab initio no-core shell model with continuum, and its applications to nucleon and deuterium scattering on light nuclei. The first investigation of the low-lying continuum spectrum of 6He within an ab initio framework that encompasses the 4He + n + n three-cluster dynamics characterizing its lowest particle-decay channel will also be briefly presented.
Secondary beams and the synthesis of exotic nuclei
Nitschke, J.M.
1985-09-01
With the advent of modern fast cycling synchrotrons capable of delivering high intensity heavy ion beams up to uranium, the production of secondary radioactive ion beams (RIBs) with sufficient intensity has become feasible. The basic production mechanism is the fragmentation of near relativistic heavy ion beams on light targets. The physical facts underlying the efficient conversion of stable beams into RIBs are: (1) at beam energies of several 100 MeV/A thick conversion targets (1 to 10 g/cm/sup 2/) can be used, which, for nuclei near stability, convert on the order of .1 to 1% of the primary beam into secondary beams, (2) the secondary beams are emitted into a narrow phase space (small transverse and longitudinal emittances), and (3) these emittances are of the correct magnitude to match the acceptances of suitably designed storage and accumulator rings. 14 refs.
Investigation of Coulomb dipole polarization effects on reactions involving exotic nuclei
NASA Astrophysics Data System (ADS)
Fernández-García, J. P.; Alvarez, M. A. G.; Chamon, L. C.
2015-07-01
We have analyzed elastic scattering angular distributions and total reaction cross sections of the exotic nuclei 11,9Li on 208Pb, at energies below and above the Coulomb barrier. For this purpose, we have used an optical potential with no adjustable parameters, composed by the nuclear São Paulo potential, derived from the nonlocal nature of the interaction, and the Coulomb dipole polarization potential, derived from the semiclassical theory of Coulomb excitation. Within this formalism, we identified an unusual long-range absorption for the +208Pb 11Li system, which is dominated by the Coulomb interaction. We compare it to the absorption mechanisms observed for +208Pb6He which, unlike those of +208Pb11Li, take place at small interacting distances, where both Coulomb and nuclear interactions are important. The proposed approach shows to be a fundamental basis to study reactions involving exotic nuclei.
Patra, S. K.; Panda, R. N.; Arumugam, P.; Gupta, Raj K.
2009-12-15
We have calculated the total nuclear reaction cross sections of exotic nuclei in the framework of the Glauber model, using as inputs the standard relativistic mean field (RMF) densities and the densities obtained from the more recently developed effective-field-theory-motivated RMF (the E-RMF). Both light and heavy nuclei are taken as the representative targets, and the light neutron-rich nuclei as projectiles. We found the total nuclear reaction cross section to increase as a function of the mass number, for both the target and projectile nuclei. The differential nuclear elastic scattering cross sections are evaluated for some selected systems at various incident energies. We found a large dependence of the differential elastic scattering cross section on incident energy. Finally, we have applied the same formalism to calculate both the total nuclear reaction cross section and the differential nuclear elastic scattering cross section for the recently discussed superheavy nucleus with atomic number Z=122.
Next-Generation Facilities for the Research with Exotic Nuclei and Super-Heavy Elements
NASA Astrophysics Data System (ADS)
Scheidenberger, Christoph
The present decade is governed by the construction and advent of new, dedicated radioactive beam facilities in several continents. These forthcoming facilities will allow to explore hitherto unknown territory in the chart of nuclei and to study new phenomena, effects and structural features in exotic nuclei. Increasing intensity of primary and secondary beams, selective and efficient separation techniques adapted to the reaction mechanisms and production methods, and sensitive instruments and detectors are the key prerequisites for new findings and exploratory measurements. The new facilities and instruments will enhance the science potential tremendously.
The structure and shape of exotic nuclei beyond the proton drip-line
Ferreira, L. S.; Arumugam, P.; Maglione, E.
2008-11-11
Proton emission from deformed nuclei with triaxial symmetry is discussed within the non-adiabatic quasi-particle approach. As an example, we consider decay from {sup 161}Re, where we were able to reproduce the experimental half-life with a noticeable {gamma} deformation.
Pushing the relative mass accuracy limit of ISOLTRAP on exotic nuclei below 10 ppb
NASA Astrophysics Data System (ADS)
Blaum, K.; Beck, D.; Bollen, G.; Herfurth, F.; Kellerbauer, A.; Kluge, H.-J.; Moore, R. B.; Sauvan, E.; Scheidenberger, C.; Schwarz, S.; Schweikhard, L.
2003-05-01
The Penning trap mass spectrometer ISOLTRAP plays a leading role in mass spectrometry of short-lived nuclides. The recent installation of a radio-frequency quadrupole trap and a carbon cluster ion source allowed for the first time mass measurements on exotic nuclei with a relative uncertainty of δ m/ m≈1×10 -8. The status of ISOLTRAP mass spectrometry and recent highlights are presented.
New Experiments with Stored Exotic Nuclei at the FRS-ESR Facility
Geissel, H.
2009-08-26
High accuracy mass and novel nuclear lifetime measurements have been performed with bare and few-electron ions produced via projectile fragmentation and fission, separated in flight and stored at relativistic energies. Characteristic experimental results and new developments are reviewed. A new generation of studies with exotic nuclei will be possible with the advent of the proposed international Facility for Antiproton and Ion Research (FAIR)
Time-of-Flight Mass Measurements of Exotic Nuclei
Matos, M.; Famiano, M.; Gade, A.; George, S.; Lynch, W. G.; Rogers, A.; Stolz, A.; Wallace, M.; Yurkon, J.
2012-01-01
Atomic masses play an important role in nuclear physics and astrophysics. The need of experimental mass values for unstable nuclides has triggered the development of a wide range of mass measurement techniques, with devices installed at many laboratories around the world. We have implemented a time-of-flight magnetic-rigidity (TOF-B ) technique at the National Superconducting Cyclotron Laboratory (NSCL) that includes a position measurement for magnetic rigidity corrections and uses the A1900 separator and the S800 spectrograph. We performed a successful first experiment measuring masses of neutron-rich isotopes in the region of Z 20 30, important for calculations of processes occurring in the crust of accreting neutron stars. The masses of 16 nuclei were determined, for 61V, 63Cr, 66Mn, and 74Ni for the first time, with atomic mass excesses of 30.510(890) MeV, 35.280(650) MeV, 36.900(790) MeV, and 49.210(990) MeV, respectively. The mass resolution achieved was 1.8 10 4.
Study of Exotic Weakly Bound Nuclei Using Magnetic Analyzer Mavr
NASA Astrophysics Data System (ADS)
Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.
2016-06-01
A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ∼1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400 - U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.
TOPICAL REVIEW: Shapes and collectivity of exotic nuclei via low-energy Coulomb excitation
NASA Astrophysics Data System (ADS)
Görgen, Andreas
2010-10-01
The way in which an atomic nucleus responds to excitations, whether by promoting individual nucleons into higher shells or by collective rotation or vibration, reveals many details of the underlying nuclear structure. The response of the nucleus is closely related to its macroscopic shape. Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei, allowing the measurement of static and dynamic electromagnetic moments as a probe of the nuclear wavefunctions. Owing to the availability of radioactive heavy-ion beams with energies near the Coulomb barrier, it is now possible to study the shape and collectivity of short-lived nuclei far from β stability (the so-called exotic nuclei), providing a particularly stringent test of modern theoretical nuclear structure models. This review gives an introduction to the experimental techniques related to low-energy Coulomb excitation with radioactive ion beams and summarizes the results that were obtained over the last 10 years for a wide variety of exotic nuclei at various laboratories employing the isotope separation on-line technique.
Mass extrapolations in the region of deformed rare Earth nuclei
Borcea, C.; Audi, G.
1998-12-21
A procedure based on the regularity property of the mass surface is proposed to make predictions for the masses of neutron rich deformed nuclei in the rare earth region. Tables are given for the estimated masses; they extend up to the presumed limit of the deformation region.
New approach for alpha-decay calculations of deformed nuclei
Ni Dongdong; Ren Zhongzhou
2010-06-15
We present a new theoretical approach to evaluate alpha-decay properties of deformed nuclei, namely the multichannel cluster model (MCCM). The deformed alpha-nucleus potential is taken into full account, and the coupled-channel Schroedinger equation with outgoing wave boundary conditions is employed for quasibound states. Systematic calculations are carried out for well-deformed even-even nuclei with Z>=98 and isospin dependence of nuclear potentials is included in the calculations. Fine structure observed in alpha decay is well described by the four-channel microscopic calculation, which is performed for the first time in alpha-decay studies. The good agreement between experiment and theory is achieved for both total alpha-decay half-lives and branching ratios to the ground-state rotational band of daughter nuclei. Predictions on the branching ratios to high-spin daughter states are presented for superheavy nuclei, which may be important to interpret future observations.
ENAM'04 Fourth International Conference on Exotic Nuclei and Atomic Masses
Gross, C. J.; Nazarewicz, W.; Rykaczewski, K. P.
2005-01-01
The conference can trace its origins to the 1950s and 1960s with the Atomic Mass and Fundamental Constants (AMCO) and the Nuclei Far From Stability (NFFS) series of conferences. Held jointly in 1992, the conferences officially merged in 1995 and the fourth conference was held at Callaway Gardens in Pine Mountain, GA and was organized by the Physics Division at Oak Ridge National Laboratory. The conference covered a broad list of topics consisting of a series of invited and contributed presentation highlighting recent research in the following fields: Atomic masses, nuclear moments, and nuclear radii; Forms of radioactivity; Nuclear structure, nuclei at the drip lines, cluster phenomena; Reactions with radioactive ion beams; Nuclear astrophysics; Fundamental symmetries and interactions; Heaviest elements and fission; Radioactive ion beam production and experimental developments; Applications of exotic nuclei
Realistic shell-model calculations and exotic nuclei around {sup 132}Sn
Covello, A.; Itaco, N.; Coraggio, L.; Gargano, A.
2008-11-11
We report on a study of exotic nuclei around doubly magic {sup 132}Sn in terms of the shell model employing a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. The short-range repulsion of the latter is renormalized by constructing a smooth low-momentum potential, V{sub low-k}, that is used directly as input for the calculation of the effective interaction. In this paper, we focus attention on proton-neutron multiplets in the odd-odd nuclei {sup 134}Sb, {sup 136}Sb. We show that the behavior of these multiplets is quite similar to that of the analogous multiplets in the counterpart nuclei in the {sup 208}Pb region, {sup 210}Bi and {sup 212}Bi.
The Subtleties of Pairing and Collective Structures in Deformed Nuclei
NASA Astrophysics Data System (ADS)
Sharpey-Schafer, J. F.
2015-11-01
It is well known that simple monopole pairing is a pretty crude approximation. It can account for the observations that the ground states of all even-even nuclei have spin-parity 01+ and that there is a pairing gap above the ground state in deformed nuclei before particle-hole configurations can be excited. As an approximation it is best for proton and neutron mid-shell nuclei where the available single particle Nilsson wavefunctions have large overlaps. However at the beginning of regions of deformation, where high-K orbitals can be bought to the Fermi surface from a lower shell, simple monopole pairing is inadequate in describing the physics of the observed data. More recently, with a considerable increase in the quantity and quality of experimental data available, configuration dependent pairing has been used to account for the properties of low-lying first excited 02+ states in N = 88 and 90 nuclei at the onset of deformation in the rare earths. The properties of 02+ states in these and other nuclei at the start of regions of deformation and the effects of blocking of pairing leading to a decrease in the backbending critical frequencies in odd nuclei are presented.
Coulomb excitation of exotic nuclei at the R3B-LAND setup
NASA Astrophysics Data System (ADS)
Rossi, D. M.; Adrich, P.; Aksouh, F.; Alvarez-Pol, H.; Aumann, T.; Benlliure, J.; Böhmer, M.; Boretzky, K.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Datta Pramanik, U.; Emling, H.; Ershova, O.; Fernandez-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Johansson, H.; Junghans, A.; Kiselev, O.; Klimkiewicz, A.; Kratz, J. V.; Kurz, N.; Labiche, M.; Le Bleis, T.; Lemmon, R.; Litvinov, Yu A.; Mahata, K.; Maierbeck, P.; Movsesyan, A.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.
2013-03-01
Exotic Ni isotopes have been measured at the R3B-LAND setup at GSI in Darmstadt, using Coulomb excitation in inverse kinematics at beam energies around 500 MeV/u. As the experimental setup allows kinematically complete measurements, the excitation energy was reconstructed using the invariant mass method. The GDR and additional low-lying strength have been observed in 68Ni, the latter exhausting 4.1(1.9)% of the E1 energy-weighted sum rule. Also, the branching ratio for the non-statistical decay of the excited 68Ni nuclei was measured and amounts to 24(4)%.
Polarization of the nuclear surface in deformed nuclei
NASA Astrophysics Data System (ADS)
Scamps, Guillaume; Lacroix, Denis; Adamian, G. G.; Antonenko, N. V.
2013-12-01
The density profiles of around 750 nuclei are analyzed using the Skyrme energy density functional theory. Among them, more than 350 nuclei are found to be deformed. In addition to rather standard properties of the density, we report a nontrivial behavior of the nuclear diffuseness as the system becomes more and more deformed. Besides the geometric effects expected in a rigid body, the diffuseness acquires a rather complex behavior leading to a reduction of the diffuseness along the main axis of deformation simultaneously with an increase of the diffuseness along the other axis. The possible isospin dependence of this polarization is studied. This effect, which is systematically seen in medium and heavy nuclei, can affect the nuclear dynamical properties. A quantitative example is given with the fusion barrier in the 40Ca+238U reaction.
Recent developments in the eikonal description of the breakup of exotic nuclei
NASA Astrophysics Data System (ADS)
Capel, P.; Colomer, F.; Esbensen, H.; Fukui, T.; Johnson, R. C.; Nunes, F. M.; Ogata, K.
2016-06-01
The study of exotic nuclear structures, such as halo nuclei, is usually performed through nuclear reactions. An accurate reaction model coupled to a realistic description of the projectile is needed to correctly interpret experimental data. In this contribution, I briefly summarise the assumptions made within the modelling of reactions involving halo nuclei. I describe briefly the Continuum-Discretised Coupled Channel method (CDCC) and the Dynamical Eikonal Approximation (DEA) in particular and present a comparison between them for the breakup of 15C on Pb at 68AMeV. I show the problem faced by the eikonal approximation at low energy and detail a correction that enables its extension down to lower beam energies. A new reaction observable is also presented. It consists of the ratio between angular distributions for two different processes, such as elastic scattering and breakup. This ratio is completely independent of the reaction mechanism and hence is more sensitive to the projectile structure than usual reaction observables, which makes it a very powerful tool to study exotic structures far from stability.
β decay of the exotic Tz=-2 nuclei 48Fe,52Ni , and 56Zn
NASA Astrophysics Data System (ADS)
Orrigo, S. E. A.; Rubio, B.; Fujita, Y.; Gelletly, W.; Agramunt, J.; Algora, A.; Ascher, P.; Bilgier, B.; Blank, B.; Cáceres, L.; Cakirli, R. B.; Ganioǧlu, E.; Gerbaux, M.; Giovinazzo, J.; Grévy, S.; Kamalou, O.; Kozer, H. C.; Kucuk, L.; Kurtukian-Nieto, T.; Molina, F.; Popescu, L.; Rogers, A. M.; Susoy, G.; Stodel, C.; Suzuki, T.; Tamii, A.; Thomas, J. C.
2016-04-01
The results of a study of the β decays of three proton-rich nuclei with Tz=-2 , namely 48Fe,52Ni , and 56Zn, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total β -delayed proton emission branching ratios. We have measured the individual β -delayed protons and β -delayed γ rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between β -delayed protons and γ rays is observed in the de-excitation of the T =2 isobaric analog states in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case 56Zn, where the exotic β -delayed γ -proton decay has been observed.
Modeling level structures of odd-odd deformed nuclei
Hoff, R.W.; Kern, J.; Piepenbring, R.; Boisson, J.P.
1985-01-15
A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation were derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings were used. Calculated and experimental level structures for /sup 238/Np, /sup 244/Am, and /sup 250/Bk are compared, as well as those for several nuclei in the rare-earch region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Corresponding average deviations for five rare-earth nuclei are 47 keV and 7%. Several applications of this modeling technique are discussed.
Modeling level structures of odd-odd deformed nuclei
Hoff, R.W.; Kern, J.; Piepenbring, R.; Boisson, J.P.
1984-09-07
A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation were derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings were used. Calculated and experimental level structures for /sup 238/Np, /sup 244/Am, and /sup 250/Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Corresponding average deviations for five rare-earth nuclei are 47 keV and 7%. Several applications of this modeling technique are discussed. 18 refs., 5 figs., 4 tabs.
Symmetry energy and surface properties of neutron-rich exotic nuclei
Gaidarov, M. K.; Antonov, A. N.; Sarriguren, P.; Moya de Guerra, E.
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.
Distortion effects on the neutron knockout from exotic nuclei in the collision with a proton target
NASA Astrophysics Data System (ADS)
Cravo, E.; Crespo, R.; Deltuva, A.
2016-05-01
Background: Reaction theory plays a major role in the interpretation of experimental data and one needs to identify and include accurately all the relevant dynamical effects in order to extract reliable structure information. The knockout of a nucleon (neutron/proton) from a high energy exotic nucleus projectile colliding with a proton target allows to get insight on the structure of its valence and inner shells. Purpose: We aim to clarify the role of the distortion on the calculated observables for nucleon knockout, in particular, the dependence of the calculated observables on the binding energy ɛb and angular momentum L of the knockout particle, and on the mass of the projectile core, Ac. We consider mainly the knockout of a neutron that may be either in the valence or in the inner shell of the projectile nucleus. Method: Exact three-body Faddeev/Alt-Grassberger-Sandhas (Faddeev/AGS) calculations are performed for the nucleon knockout from stable and exotic nuclei in the collision of 420 MeV/u projectile beams with a proton target. Results are compared with plane-wave impulse approximation (PWIA) calculations. Results: The Faddeev/AGS formalism accurately predicts: (i) a systematic nearly logarithmic dependence of the distortion parameter on the separation energy; (ii) roughly linear dependence of the ratio of the full to the PWIA cross section on the asymmetry parameter; (iii) a distinct behavior between the calculated transverse core momentum distribution from the PWIA and full Faddeev/AGS exact approach which indicates that distortion effects do not modify fully exclusive observables through a common renormalization factor. Conclusions: To extract structure information on deeper shells one needs to include distortion effects accurately. A systematic analysis enables to estimate the total cross section for knockout of a nucleon from a given shell of nuclei at/away the stability line of the nuclear landscape. The comparison with experimental results may
Collisions of deformed nuclei and superheavy-element production
Iwamoto, Akira; Moeller, P. |||; Nix, J.R.; Sagawa, Hiroyuki, Sagawa
1995-09-01
A detailed understanding of complete fusion cross sections in heavy-ion collisions requires a consideration of the effects of the deformation of the projectile and target. The aim here is to show that deformation and orientation of the colliding nuclei have a very significant effect on the fusion-barrier height and on the compactness of the touching configuration. To facilitate discussions of fusion configurations of deformed nuclei, the authors develop a classification scheme and introduce a notation convention for these configurations. They discuss particular deformations and orientations that lead to compact touching configurations and to fusion-barrier heights that correspond to fairly low excitation energies of the compound systems. Such configurations should be the most favorable for producing superheavy elements. They analyze a few projectile-target combinations whose deformations allow favorable entrance-channel configurations and whose proton and neutron numbers lead to compound systems in a part of the superheavy region where a half-lives are calculated to be observable, that is, longer than 1 {micro}s.
The Onset of Deformation in Neutron-Deficient At Nuclei
Smith, M.B.; Chapman, R.; Cocks, J.F.C.; Dorvaux, O.; Helariutta, K.; Jones, P.M.; Julin, R.; Juutinen, S.; Kankaanpaa, H.; Kettunen, H.; Kuusiniemi, P.; Le Coz, Y.; Leino, M.; Middleton, D.J.; Muikku, M.; Nieminen, P.; Rahkila, P.; Savelius, A.; Spohr, K.-M.
1999-12-31
Excited states in the {sup 197}At nucleus have been identified for the first time using the recoil-decay-tagging technique. The excitation energy of these states is found to be consistent with the systematics of neutron-deficient At nuclei and with calculations indicating that the nucleus may be deformed in its ground state. A more recent experiment, to study states in {sup 195}At, is discussed.
The onset of deformation in neutron-deficient At nuclei
Smith, M. B.; Chapman, R.; Middleton, D. J.; Spohr, K.-M.; Cocks, J. F. C.; Dorvaux, O.; Helariutta, K.; Jones, P. M.; Julin, R.; Juutinen, S.; Kankaanpaeae, H.; Kettunen, H.; Kuusiniemi, P.; Leino, M.; Muikku, M.; Nieminen, P.; Rahkila, P.; Savelius, A.; Coz, Y. Le
1999-11-16
Excited states in the {sup 197}At nucleus have been identified for the first time using the recoil-decay-tagging technique. The excitation energy of these states is found to be consistent with the systematics of neutron-deficient. At nuclei and with calculations indicating that the nucleus may be deformed in its ground state. A more recent experiment, to study states in {sup 195}At, is discussed.
Microscopic and self-consistent description for neutron halo in deformed nuclei
Li Lulu; Meng Jie; Zhao Enguang; Zhou Shangui
2013-05-06
A deformed relativistic Hartree-Bogoliubov theory in continuum has been developed for the study of neutron halos in deformed nuclei and the halo phenomenon in deformed weakly bound nuclei is investigated. Magnesium and neon isotopes are studied and some results are presented for the deformed neutron-rich and weakly bound nuclei {sup 44}Mg and {sup 36}Ne. The core of the former 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 existence of halos in deformed nuclei and for the occurrence of this decoupling effect are discussed.
NASA Astrophysics Data System (ADS)
Geissel, H.; Chen, L.; Dickel, T.; Farinon, F.; Dillmann, I.; Knöbel, R.; Kurcewicz, J.; Mukha, I.; Münzenberg, G.; Nociforo, C.; Patyk, Z.; Pietri, S.; Plass, W. R.; Prochazka, A.; Scheidenberger, C.; Takechi, M.; Weick, H.; Winfield, J. S.; Winkler, M.
2014-03-01
Precision experiments with relativistic fragments separated in-flight require special experimentalmethods to overcome the inherent large emittance from the creation in nuclear reactions and atomic interactions in matter. At GSI relativistic exotic nuclei have been produced via uranium projectile fragmentation and fission and investigated with the inflight separator FRS directly, or in combination with either the storage-cooler ring ESR or the FRS Ion Catcher. 1000 A·MeV 238U ions were used to create 60 new neutron-rich isotopes separated and identified with the FRS to measure their production cross sections. In another experimental campaign the fragments were separated in flight and injected into the storage-cooler ring ESR for accurate mass and lifetime measurements. In these experimentswe have obtained accurate new mass values analyzed via a novel method which has reduced the systematic errors for both Schottky Mass Spectrometry (SMS) and for Isochronous Mass Spectrometry (IMS). Pioneering experiments have been carried out with the FRS Ion Catcher consisting of three experimental components, the dispersive magnetic system of the FRS with a monoenergetic and a homogeneous degrader, a cryogenic stopping cell filled with pure helium and a multiple-reflection time-of flight mass separator. The FRS Ion Catcher enables high precision spectroscopy experiments with eV to keV exotic nuclides. Results from these different FRS experiments are presented in this overview together with prospects for the next-generation facility Super-FRS. The novel features of the Super-FRS compared with the present FRS will be discussed in addition.
Beta decay of exotic TZ = -1, -2 nuclei: the interesting case of 56Zn
NASA Astrophysics Data System (ADS)
Orrigo, S. E. A.; Rubio, B.; Fujita, Y.; Blank, B.; Gelletly, W.; Agramunt, J.; Algora, A.; Ascher, P.; Bilgier, B.; Cáceres, L.; Cakirli, R. B.; Fujita, H.; Ganioğlu, E.; Gerbaux, M.; Giovinazzo, J.; Grévy, S.; Kamalou, O.; Kozer, H. C.; Kucuk, L.; Kurtukian-Nieto, T.; Molina, F.; Popescu, L.; Rogers, A. M.; Susoy, G.; Stodel, C.; Suzuki, T.; Tamii, A.; Thomas, J. C.
2014-03-01
The β decay properties of the Tz = -2, 56Zn isotope and other proton-rich nuclei in the fp-shell have been investigated in an experiment performed at GANIL. The ions were produced in fragmentation reactions and implanted in a double-sided silicon strip detector surrounded by Ge EXOGAM clovers. Preliminary results for 56Zn are presented .The 56Zn decay proceeds mainly by β delayed proton emission, but β delayed gamma rays were also detected. Moreover, the exotic β delayed gamma-proton decay was observed for the first time. The 56Zn half-life and the energy levels populated in the 56Cu daughter have been determined. Knowledge of the gamma de-excitation of the mirror states in 56Co and the comparison with the results of the mirror charge exchange process, the 56Fe(3He,t) reaction (where 56Fe has Tz = +2), were important in the interpretation of the 56Zn decay data. The absolute Fermi and Gamow-Teller strengths have been deduced.
Dasgupta-Schubert, N.; Reyes, M. A.; Tamez, V. A.
2009-04-20
Alpha decay is one of the two main decay modes of the heaviest nuclei, (SHE), and constitutes one of the dominant decay modes of highly neutron deficient medium mass nuclei ('exotics'). Thus identifying and characterizing the alpha decay chains form a crucial part of the identification of SHE. We report the extension of the previously developed method for the detailed and systematic investigation of the reliability of the three main extant analytical formulae of alpha decay half-lives: the generalized liquid drop model based formula of Royer et al. (FR), the Sobiczewski modified semi-empirical Viola-Seaborg formula (VSS) and the recent phenomenological formula of Sobiczewski and Parkhomenko (SP)
Deformed Brueckner-Hartree-Fock calculation for light nuclei
NASA Technical Reports Server (NTRS)
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.
NASA Astrophysics Data System (ADS)
Bacca, Sonia
2016-04-01
A brief review of models to describe nuclear structure and reactions properties is presented, starting from the historical shell model picture and encompassing modern ab initio approaches. A selection of recent theoretical results on observables for exotic light and medium-mass nuclei is shown. Emphasis is given to the comparison with experiment and to what can be learned about three-body forces and continuum properties.
Tunneling from super- to normal-deformed minima in nuclei.
Khoo, T. L.
1998-01-08
An excited minimum, or false vacuum, gives rise to a highly elongated superdeformed (SD) nucleus. A brief review of superdeformation is given, with emphasis on the tunneling from the false to the true vacuum, which occurs in the feeding and decay of SD bands. During the feeding process the tunneling is between hot states, while in the decay it is from a cold to a hot state. The {gamma} spectra connecting SD and normal-deformed (ND) states provide information on several physics issues: the decay mechanism; the spin/parity quantum numbers, energies and microscopic structures of SD bands; the origin of identical SD bands; the quenching of pairing with excitation energy; and the chaoticity of excited ND states at 2.5-5 MeV. Other examples of tunneling in nuclei, which are briefly described, include the possible role of tunneling in {Delta}I = 4 bifurcation in SD bands, sub-barrier fusion and proton emitters.
Role of higher-multipole deformations in exotic {sup 14}C cluster radioactivity
Sawhney, Gudveen; Sharma, Manoj K.; Gupta, Raj K.
2011-06-15
We have studied nine cases of spontaneous emission of {sup 14}C clusters in the ground-state decays of the same number of parent nuclei from the trans-lead region, specifically from {sup 221}Fr to {sup 226}Th, using the preformed cluster model (PCM) of Gupta and collaborators, with choices of spherical, quadrupole deformation ({beta}{sub 2}) alone, and higher-multipole deformations ({beta}{sub 2}, {beta}{sub 3}, {beta}{sub 4}) with cold ''compact'' orientations {theta}{sup c} of decay products. The calculated {sup 14}C cluster decay half-life times are found to be in nice agreement with experimental data only for the case of higher-multipole deformations ({beta}{sub 2}-{beta}{sub 4}) and {theta}{sup c} orientations of cold elongated configurations. In other words, compared to our earlier study of clusters heavier than {sup 14}C, where the inclusion of {beta}{sub 2} alone, with ''optimum'' orientations, was found to be enough to give the best comparison with data, here for {sup 14}C cluster decay the inclusion of higher-multipole deformations (up to hexadecapole), together with {theta}{sup c} orientations, is found to be essential on the basis of the PCM. Interestingly, whereas both the penetration probability and assault frequency work simply as scaling factors, the preformation probability is strongly influenced by the order of multipole deformations and orientations of nuclei. The possible role of Q value and angular-momentum effects are also considered in reference to {sup 14}C cluster radioactivity.
The nuclear structure of deformed odd-odd nuclei: Experimental and theoretical investigations
Hoff, R.W.; Jain, A.K.; Sood, P.C.; Sheline, R.K.
1988-06-06
Previous surveys of experimental level structure in deformed odd-odd nuclei have been updated with recent results for the lanthanide and actinide regions. The relative strengths of the effective neutron-proton interaction derived from these data are compared. The predictive power of a semi-empirical model for level structure in deformed odd-odd nuclei is demonstrated. Comparison is made with recent Hartree-Fock calculations of selected nuclei.
Exotic decay modes of odd-Z (105-119) superheavy nuclei
NASA Astrophysics Data System (ADS)
Rajeswari, N. S.; Balasubramaniam, M.
2014-06-01
Half-lives of proton emission for proton emitters with Z = 51 to 83 are calculated, in the frame-work of unified fission model with the penetrability calculated using the WKB approximation. For all the ground and isomeric state of the proton, the deformation degree of freedom is included. Calculated half-lives are in good agreement with the experimental ones. Experimentally for a few isotopes, proton and alpha branches are reported. Hence we have calculated the half-lives of alpha decay for these elements. For parent nuclei 157Ta, 166Ir, 167Ir, 176Tl and 177Tl, the alpha decay mode is preferred over the proton emission. Further, the calculations are extended to find half-lives of superheavy element with odd proton number in the range Z = 105 to 119, for both proton, alpha and for a few cluster decays. Calculations on superheavy elements reveal that cluster radioactivity has half-lives comparable with proton emissions. It is found that proton emission is the primary competing decay mode with respect to alpha decay for superheavy elements. Among considered clusters, 12C, 20Ne and 24Mg are found to have lowest half-lives among other N = Z clusters and for a few clusters the half-lives are found to be comparable with that of proton emission.
NASA Astrophysics Data System (ADS)
Sun, Bao-Hua; Zhao, Jian-Wei; Yan, Wen-Qi; Le, X. Y.; Lin, Wen-Jian; Song, C. Y.; Tanihata, Isao; Terashima, S.; Wang, T. F.; Zhang, S. S.; Zhu, L. H.
2016-02-01
The time-of-flight (TOF) mass spectrometry (MS), a high-resolution magnetic spectrometer equipped with a fast particle tracking system, is well recognized by its ability in weighing the most exotic nuclei. Currently such TOF-MS can achieve a mass resolution power of about 2×10-4. We show that the mass resolution can be further improved by one order of magnitude with augmented timing and position detectors. We report the progress in developing ultra-fast detectors to be used in TOF-MS.
NASA Astrophysics Data System (ADS)
Fritsch, A.; Ayyad, Y.; Bazin, D.; Beceiro-Novo, S.; Bradt, J.; Carpenter, L.; Cortesi, M.; Mittig, W.; Suzuki, D.; Ahn, T.; Kolata, J. J.; Becchetti, F. D.; Howard, A. M.
2016-03-01
Some exotic nuclei appear to exhibit α-cluster structure. While various theoretical models currently describe such clustering, more experimental data are needed to constrain model predictions. The Prototype Active-Target Time-Projection Chamber (PAT-TPC) has low-energy thresholds for charged-particle decay and a high luminosity due to its thick gaseous active target volume, making it well-suited to search for low-energy α-cluster reactions. Radioactive-ion beams produced by the TwinSol facility at the University of Notre Dame were delivered to the PAT-TPC to study nuclei including 14C and 14O via α-resonant scattering. Differential cross sections and excitation functions were measured. Preliminary results from our recent experiments will be presented. This work is supported by the U.S. National Science Foundation.
Two-neutron transfer reactions with heavy-deformed nuclei
Price, C.; Landowne, S.; Esbensen, H.
1988-01-01
In a recent communication we pointed out that one can combine the macroscopic model for two-particle transfer reactions on deformed nuclei with the sudden limit approximation for rotational excitation, and thereby obtain a practical method for calculating transfer reactions leading to high-spin states. As an example, we presented results for the reaction WSDy(VYNi,WNi) WDy populating the ground-state rotational band up to the spin I = 14 state. We have also tested the validity of the sudden limit for the inelastic excitation of high spin states and we have noted how the macroscopic model may be modified to allow for more microscopic nuclear structure effects in an application to diabolic pair-transfer processes. This paper describes our subsequent work in which we investigated the systematic features of pair-transfer reactions within the macroscopic model by using heavier projectiles to generate higher spins and by decomposing the cross sections according to the multipolarity of the transfer interaction. Particular attention is paid to characteristic structures in the angular distributions for the lower spin states and how they depend on the angular momentum carried by the transferred particles. 11 refs., 3 figs.
Possible octupole deformation in Cs and Ba nuclei from their differential radii
Sheline, R.K.; Jain, A.K.; Jain, K.
1988-12-01
The odd-even staggering of the differential radii of Fr and Ra and the Cs and Ba nuclei is compared. This staggering is inverted in the region of known octupole deformation in the Fr and Ra nuclei. The normal staggering is eliminated in the Cs nuclei and attenuated in the Ba nuclei for neutron numbers 85--88. This fact is used to suggest the possible existence of octupole deformation and its neutron number range in the Cs and Ba nuclear ground states.
{Delta}I = 2 energy staggering in normal deformed dysprosium nuclei
Riley, M.A.; Brown, T.B.; Archer, D.E.
1996-12-31
Very high spin states (I{ge}50{Dirac_h}) have been observed in {sup 155,156,157}Dy. The long regular band sequences, free from sharp backbending effects, observed in these dysprosium nuclei offer the possibility of investigating the occurence of any {Delta}I = 2 staggering in normal deformed nuclei. Employing the same analysis techniques as used in superdeformed nuclei, certain bands do indeed demonstrate an apparent staggering and this is discussed.
Gamow-Teller Transitions in Proton Rich Exotic pf-shell Nuclei Deduced from Mirror Transitions
Fujita, Y.; Adachi, T.; Fujita, H.; Blank, B.; Brentano, P. von; Zell, K. O.; Berg, G. P. A.; Fujita, K.; Hatanaka, K.; Nakanishi, K.; Shimizu, Y.; Tameshige, Y.; Tamii, A.; Yosoi, M.; Negret, A.; Popescu, L.; Rubio, B.; Shimbara, Y.
2010-08-12
The rp-process nucleosynthesis proceeds through nuclei near the proton drip-line, in which Gamow-Teller (GT) transitions starting from unstable pf-shell nuclei play important roles. In the {beta}-decay study of these nuclei, half-lives can be measured rather accurately. On the other hand, in the high-resolution ({sup 3}He, t) charge-exchange reactions on mirror nuclei, individual GT transitions can be studied up to high excitations. For the accurate study of the GT transition strengths in the A = 52, T = 2, system, we compare and combine the {beta}-decay study of the proton-rich nucleus {sup 52}Ni and the {sup 52}Cr({sup 3}He, t) measurement assuming the isospin symmetry of the T{sub z} = {+-}2{yields}{+-}1 transitions.
NASA Astrophysics Data System (ADS)
Mitchell, Joseph P.
. Occurrence of rp-nucleosynthesis in these objects may make important sources of the chemical enrichment of isotopes below the iron group that are not know to be synthesized in hydrostatic stellar burning. The existence of rp-breakout in the flashes, shows the importance of nuclear physics in these objects. More precise nuclear reaction rate data are needed for proper energy generation and chemical evolution. With the occurrence of rp-nucleosynthesis in our models, it is especially advantageous to study radioactive proton rich nuclei. These studies are not without many difficulties in the laboratory, as many of the studies require the use of low intensity radioactive beams making clean, high statistic studies difficult. To address this issue, the hybrid target technique was used. This target technique was found to be a great tool for studying resonant proton scattering with exotic beams. It has been used to measure elastic and inelastic excitation functions in the study of 8B via 7Be+p scattering, as well as 12N+p elastic scattering. With such success, the hybrid target technique can be a very useful tool for studying reactions that are important in the rp-process. We have studied the structure of the astrophysically important, radioactive isotope 8B. Three new resonances have been suggested, a 0+1,2+2 , and 1+2 which were predominantly in the inelastic channel and never before seen in previous studies. However, due to their high excitation energies and narrow width, none of the resonances are expected to effect the astrophysically important 7Be(p, gamma) reaction rate. Results were compared to continuum shell model as well as ab initio calculations and found to be in good agreement with both sets of predictions, with the notable exception of the 2+2 state. (Abstract shortened by UMI.)
Studies of light exotic nuclei in the vicinity of neutron and proton drip lines at FLNR JINR
NASA Astrophysics Data System (ADS)
Grigorenko, L. V.; Golovkov, M. S.; Krupko, S. A.; Sidorchuk, S. I.; Ter-Akopian, G. M.; Fomichev, A. S.; Chudoba, V.
2016-04-01
Defining the limits of the existence of the nuclear structure is one of fundamental problems of natural science, requiring the advancement of studies towards the sites of maximum neutron- and proton-excess nuclei, to the borders of nuclear stability, and further, to the regions of nuclear instability. In such regions, nuclear systems exist only as resonant states in continuous spectra with characteristic 'nuclear' lifetimes. This work is done most effectively with experimental setups providing radioactive ion beams (RIBs). This review discusses the approaches in this field of research developed during the last 20 years at the ACCULINNA fragment separator in the Flerov Laboratory of Nuclear Reactions (FLNR) of the Joint Institute for Nuclear Research (JINR). The methodology developed is based on the comprehensive study of correlations among the reaction fragments emitted in the decays of nuclear-unstable systems which are populated in direct reactions induced by RIBs with intermediate (20 – 60 MeV per nucleon) energies. This allows us to acquire detailed knowledge about exotic nuclear systems close to and beyond nuclear drip lines. We discuss exotic forms of nuclear dynamics appearing in the vicinity of nuclear drip lines and relevant results of their theoretical analysis. Also discussed are existing facilities and prospective projects aimed at nuclear structure studies with RIBs at JINR.
Coupled-channels study of fine structure in the {alpha} decay of well deformed nuclei
Ni Dongdong; Ren Zhongzhou
2011-06-15
We formulate a theoretical model for the {alpha} decay of well-deformed even-even nuclei based on the coupled-channel Schroedinger equation. The {alpha}-decay half-lives and fine structures observed in {alpha} decay are well described by the five-channel microscopic calculations. Since the branching ratios to high-spin states are hard to understand in the traditional {alpha}-decay theories, this success could be important to interpret future observations of heavier nuclei. It is also found that the {alpha} transition to high-spin states is a powerful tool to probe the energy spectrum and deformation of daughter nuclei.
Extended systematics of alpha decay half lives for exotic superheavy nuclei
NASA Astrophysics Data System (ADS)
Budaca, A. I.; Budaca, R.; Silisteanu, I.
2016-07-01
The experimentally available data on the α decay half lives and Qα values for 96 superheavy nuclei are used to fix the parameters for a modified version of the Brown empirical formula through two fitting procedures which enables its comparison with similar fits using Viola-Seaborg and Royer formulas. The new expressions provide very good agreement with experimental data having fewer or the same number of parameters. All formulas with the obtained parameters are then extrapolated to generate half lives predictions for 125 unknown superheavy α emitters. The nuclei where the employed empirical formulas maximally or minimally diverge are pointed out and a selection of 36 nuclei with exceptional superposition of predictions was made for experimental reference.
Microscopic Description of the Exotic Nuclei Reactions by Using Folding model Potentials
Ibraheem, Awad A.; Hassanain, M. A.; Mokhtar, S. R.; El-Azab Farid, M.; Zaki, M. A.; Mahmoud, Zakaria M. M.
2011-10-27
A microscopic folding approach based upon the effective M3Y nucleon-nucleon interaction and the nuclear matter densities of the interacting nuclei has been carried out to explain recently measured experimental data of the {sup 6}He+{sup 120}Sn elastic scattering reaction at four different laboratory energies near the Coulomb barrier. The corresponding reaction cross sections are also considered.
Proximity potential for heavy ion reactions on deformed nuclei
Baltz, A. J.; Bayman, B. F.
1982-01-01
The usual treatment of the deformed optical model for analysis of heavy ion induced inelastic scattering data involves a deformed (target) radius, a spherical (projectile) radius and a potential strength dependent on the surface separation along the line between the two centers. Several authors using various approaches have shown that this center line potential is geometrically inadequate especially for description of higher L deformation parameters probed in heavy ion induced inelastic scattering experiments. A quantitatively adequate form of the deformed proximity potential suitable for use with a coupled channels reaction code in the analysis of inelastic scattering data above the Coulomb barrier is described. A major objective is to be able to extract reliably higher deformed multipole moments from such data. The deformed potential calculated in the folding model will serve as a geometrically exact benchmark to evaluate the accuracy of the proximity potential prescriptions. (WHK)
{alpha}-cluster structure and exotic states in a self-consistent model for light nuclei
Maruhn, J. A.; Kimura, Masaaki; Schramm, S.; Reinhard, P.-G.; Horiuchi, H.; Tohsaki, A.
2006-10-15
In this article we examine to what extent traces of {alpha} clustering can be found in mean-field ground states of n{alpha} nuclei from {sup 8}Be through {sup 36}Ar as well as in some superdeformed states in {sup 32}S, {sup 36}Ar, and {sup 40}Ca. For this purpose we calculate the overlap of the mean-field Slater determinant with one containing pure Gaussians and perfect spin and isospin symmetry, optimizing the overlap by varying the {alpha}-particle positions and radii. In some cases a coherent sum over different configurations is also employed. We find quite large overlaps for some of the lighter systems that diminish for nuclei above {sup 20}Ne but again strong clustering in {sup 36}Ar.
Samarin, V. V.
2010-08-15
A new method for numerically solving the Schroedinger equation for an arbitrary axisymmetric field with allowance for spin-orbit interaction is used to study neutron and proton states in strongly deformed nuclei and dinuclear systems produced at the first step of the fusion of nuclei. A quadrupole-octupole parametrization is proposed for the shape of a dinuclear system and for the potential energy of nucleons in this system. The experimentally observed deformations of the {sup 26,27,28}Mg nuclei and the difference in the cross sections for the fusion of nuclei in the {sup 18}O + {sup 58}Ni and {sup 16}O + {sup 60}Ni systems are explained qualitatively.
Constrained Hartree-Fock Theory and Study of Deformed Structures of Closed Shell Nuclei
NASA Astrophysics Data System (ADS)
Praharaj, Choudhury
2016-03-01
We have studied some N or Z = 50 nuclei in a microscopic model with effective interaction in a reasonably large shell model space. Excitation of particles across 50 shell closure leads to well-deformed excited prolate configurations. The potential energy surfaces of nuclei are studied using Hartree-Fock theory with quadrupole constraint to explore the various deformed configurations of N = 50 nuclei 82Ge , 84Se and 86Kr . Energy spectra are calculated from various intrinsic states using Peierls-Yoccoz angular momentum projection technique. Results of spectra and electromagnetic moments and transitions will be presented for N = 50 nuclei and for Z = 50 114Sn nucleus. Supported by Grant No SB/S2/HEP-06/2013 of DST.
Effects of high-order deformation on high-K isomers in superheavy nuclei
Liu, H. L.; Bertulani, C. A.; Xu, F. R.; Walker, P. M.
2011-01-15
Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of {beta}{sub 6} deformation, we find remarkable effects of the high-order deformation on the high-K isomers in {sup 254}No, the focus of recent spectroscopy experiments on superheavy nuclei. For shapes with multipolarity six, the isomers are more tightly bound and, microscopically, have enhanced deformed shell gaps at N=152 and Z=100. The inclusion of {beta}{sub 6} deformation significantly improves the description of the very heavy high-K isomers.
NASA Astrophysics Data System (ADS)
Nazarewicz, W.; Riley, M. A.; Garrett, J. D.
1990-05-01
Noncollective single-proton states in odd- Z (Eu, Tb, Ho, Tm, Lu, Ta, Ir and Au) rare-earth nuclei have been calculated using the shell correction method with an average Woods-Saxon potential and a monopole pairing residual interaction. Calculated equilibrium deformations of the lowest single-proton states are presented, and calculated band head excitation energies are compared with experimental proton band heads for odd- Z rare-earth nuclei. Good agreement is found between the experimental and calculated band heads. We find that strong polarisation effects due to the odd proton explain many of the systematic trends of known band heads. Different deformation driving forces of the odd-proton orbitals can also partly explain deviations seen in high-spin data. Shape co-existence effects in Ir and Au isotopes are discussed. In addition, equilibrium deformations of even-even rare-earth nuclei are computed and compared with experimental values.
The Discoveries of Bohrium, Hassium, Meitnerium, and the New Region of Deformed Shell Nuclei
NASA Astrophysics Data System (ADS)
Muenzenberg, Gottfried
2003-03-01
The investigation of the light trans-actinide elements was not only exciting as it included the discovery of a number of new chemical elements. It led also to the discovery of a new region of shell nuclei existing beyond the macroscopic stability limit. Theory explained this in terms of a new shell region of deformed nuclei which bridge the trans-uranium nuclei and the predicted superheavy elements. This contribution will give a brief historic overview over these discoveries, experimental developments, and the impact on ongoing and future superheavy-element research.
Energy dependence of exotic nuclei production cross sections by photofission reaction in GDR range
NASA Astrophysics Data System (ADS)
Bhowmick, Debasis; Khan, F. A.; Atta, Debasis; Basu, D. N.; Chakrabarti, Alok
2016-02-01
Photofission of actinides is studied in the region of nuclear excitation energies that covers the entire giant dipole resonance (GDR) region. The mass distributions of $^{238}$U photofission fragments have been explored theoretically for eight different endpoint bremsstrahlung energies from 11.5 MeV to 67.7 MeV which correspond to average photon energy of 9.09 MeV to 15.90 MeV. Among these energies, the 29.1 MeV corresponds to the average photon energy of 13.7$\\pm$0.3 MeV which coincides with GDR peak for $^{238}$U photofission. The integrated yield of $^{238}$U photofission as well as charge distribution of photofission products are calculated and its role in producing nuclei and their neutron-richness is investigated.
Cluster radioactivity with effects of deformations and orientations of nuclei included
Arun, Sham K.; Gupta, Raj K.; Kanwar, Shefali; Singh, BirBikram; Sharma, Manoj K.
2009-09-15
Based on the preformed cluster model (PCM) of Gupta and collaborators, we have extended our recent study on ground-state cluster decays to parent nuclei resulting in daughters other than spherical {sup 208}Pb, i.e., to deformed daughters, and the very new cases of {sup 14}C and {sup 15}N decays of {sup 223}Ac, and {sup 34}Si decay of {sup 238}U, taking nuclei as spherical, quadrupole deformed ({beta}{sub 2}) alone, and with higher multipole deformations up to hexadecapole ({beta}{sub 2}, {beta}{sub 3}, {beta}{sub 4}) together with the 'optimum' orientations of cold decay process. Except for {sup 14}C decays of {sup 221}Fr, {sup 221-224,226}Ra, and {sup 225}Ac where higher multipole deformations up to {beta}{sub 4} are found essential, the quadrupole deformation {beta}{sub 2} alone is found good enough to fit the experimental data. Because the PCM treats the cluster-decay process as the tunneling of a preformed cluster, the deformations and orientations of nuclei modify both the preformation probability P{sub 0} and tunneling probability P, and hence the decay half-life, considerably.
NASA Astrophysics Data System (ADS)
Plaß, Wolfgang R.; Dickel, Timo; Ayet San Andres, Samuel; Ebert, Jens; Greiner, Florian; Hornung, Christine; Jesch, Christian; Lang, Johannes; Lippert, Wayne; Majoros, Tamas; Short, Devin; Geissel, Hans; Haettner, Emma; Reiter, Moritz P.; Rink, Ann-Kathrin; Scheidenberger, Christoph; Yavor, Mikhail I.
2015-11-01
A class of multiple-reflection time-of-flight mass spectrometers (MR-TOF-MSs) has been developed for research with exotic nuclei at present and future accelerator facilities such as GSI and FAIR (Darmstadt), and TRIUMF (Vancouver). They can perform highly accurate mass measurements of exotic nuclei, serve as high-resolution, high-capacity mass separators and be employed as diagnostics devices to monitor the production, separation and manipulation of beams of exotic nuclei. In addition, a mobile high-resolution MR-TOF-MS has been developed for in situ applications in analytical mass spectrometry ranging from environmental research to medicine. Recently, the MR-TOF-MS for GSI and FAIR has been further developed. A novel RF quadrupole-based ion beam switchyard has been developed that allows merging and splitting of ion beams as well as transport of ions into different directions. It efficiently connects a test and reference ion source and an auxiliary detector to the system. Due to an increase in the kinetic energy of the ions in the time-of-flight analyzer of the MR-TOF-MS, a given mass resolving power is now achieved in less than half the time-of-flight. Conversely, depending on the time-of-flight, the mass resolving power has been increased by a factor of more than two.
Pygmy Dipole Strength in Exotic Nuclei and the Equation of State
NASA Astrophysics Data System (ADS)
Klimkiewicz, A.; Paar, N.; Adrich, P.; Fallot, M.; le Bleis, T.; Rossi, D.; Boretzky, K.; Aumann, T.; Alvarez-Pol, H.; Aksouh, F.; Benlliure, J.; Berg, T.; Boehmer, M.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Pramanik, U. Datta; Elze, Th. W.; Emling, H.; Ershova, O.; Fernando-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Hellström, M.; Johansson, H.; Jones, K. L.; Junghans, A.; Kiselev, O.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Labiche, M.; Lemmon, R.; Litvinov, Y.; Mahata, K.; Maierbeck, P.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Surówka, G.; Vretenar, D.; Wagner, A.; Waluś, W.; Weick, H.; Winkler, M.
2009-08-01
A concentration of dipole strength at energies below the giant dipole resonance was observed in neutron-rich nuclei around 132Sn in an experiment using the FRS-LAND setup. This so-called "pygmy" dipole strength can be related to the parameters of the symmetry energy and to the neutron skin thickness on the grounds of a relativistic quasiparticle random-phase approximation. Using this ansatz and the experimental findings for 130Sn and 132Sn, we derive a value of the symmetry energy pressure of p¯0 = 2.2±0.5 MeV/fm3. Neutron skin thicknesses of Rn-Rp = 0.23±0.03 fm and 0.24±0.03 fm for 130Sn and 132Sn, respectively, have been determined. Preliminary results on 68Ni from a similar experiment using an improved setup indicate an enhanced cross section at low energies, while the results for 58Ni are in accordance with results from photoabsorption measurements.
High-Resolution Magnetic Analyzer MAVR for the Study of Exotic Weakly-Bound Nuclei
NASA Astrophysics Data System (ADS)
Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.
2015-11-01
A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ~1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400-U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.
Projected shell model for Gamow-Teller transitions in heavy, deformed nuclei
NASA Astrophysics Data System (ADS)
Wang, Long-Jun; Sun, Yang; Gao, Zao-Chun; Kiran Ghorui, Surja
2016-02-01
Calculations of Gamow-Teller (GT) transition rates for heavy, deformed nuclei, which are useful input for nuclear astrophysics studies, are usually done with the quasiparticle random-phase approximation. We propose a shell-model method by applying the Projected Shell Model (PSM) based on deformed bases. With this method, it is possible to perform a state-by-state calculation for nuclear matrix elements for β-decay and electron-capture in heavy nuclei. Taking β- decay from 168Dy to 168Ho as an example, we show that the known experimental B(GT) from the ground state of the mother nucleus to the low-lying states of the daughter nucleus could be well described. Moreover, strong transitions to high-lying states are predicted to occur, which may considerably enhance the total decay rates once these nuclei are exposed to hot stellar environments.
Sharipov, Sh.; Ermamatov, M. J.
2009-01-15
The previously developed rotationally single-particle and vibrational model of the triaxial deformable odd nuclei is extended to the case where the total angular momentum of an external nucleon is not conserved. The calculated ratios of the excitation energies of the {sup 157,159}Tb nuclei are compared with the existing experimental data. The ratios of E2-transition probabilities and those of quadrupole moments of the above nuclei are calculated using parameters determined from the spectra of these nuclei.
Orientation effects of deformed nuclei on the production of superheavy elements
Wang Nan; Li Junqing; Zhao Enguang
2008-11-15
Within the dinuclear system model, the effects of the relative orientations of interacting deformed nuclei on the interaction potential energy surfaces, the evaporation residue cross sections of some cold fusion reactions leading to superheavy elements are investigated. The competition between fusion and quasifission is studied to show the effect of the orientation. It turns out that the belly-belly orientation is in favor of the production of superheavy nuclei, because in the case a barrier has suppressed the quasifission and thus helped fusion.
Relativistic Energy Density Functionals: Exotic modes of excitation
Vretenar, D.; Paar, N.; Marketin, T.
2008-11-11
The framework of relativistic energy density functionals has been applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of {beta}-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure have been investigated with the relativistic quasiparticle random-phase approximation. We present results for the evolution of low-lying dipole (pygmy) strength in neutron-rich nuclei, and charged-current neutrino-nucleus cross sections.
High Spin States and Octupole Deformation in Neutron-Rich ^145,147La Nuclei
NASA Astrophysics Data System (ADS)
Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Babu, B. R. S.; Jones, E. F.; Kormicki, J.; Daniel, A. V.; Hwang, J. K.; Beyer, C. J.; Wang, M. G.; Long, G. L.; Li, M.; Zhu, L. Y.; Gan, C. Y.; Ma, W. C.; Cole, J. D.; Aryaeinejad, R.; Dardenne, Y. X.; Drigert, M. W.; Rasmussen, J. O.; Asztalos, S.; Lee, I. Y.; Macchiavelli, A. O.; Chu, S. Y.; Gregorich, K. E.; Mohar, M. F.; Stoyer, M. A.; Lougheed, R. W.; Moody, K. J.; Wild, J. F.; Prussin, S. G.
1998-04-01
High spin states in neutron-rich odd-Z nuclei ^145,147La have been investigated from the study of prompt γ- rays in spontaneous fission of ^252Cf by using γ-γ- and γ-γ-γ- coincidence techniques. Alternating parity bands are extended up to spins I=(41/2) and I=(43/2) in ^145La and ^147La, respectively. Strong E1 transitions between the negative and positive parity bands give evidence for stable octupole deformation. The new higher spin levels give evidence for rotational enhancement of the stability of the octupole deformation. These collective bands show competition and co-existence between symmetric and asymmetric shapes in ^145La. Band crossing was found around hbarω≈ 0.26 ~0.30 MeV in both nuclei and these backbends are related to the alignment of two i_13/2 neutron from cranked shell model calculations.
Effective field theory of emergent symmetry breaking in deformed atomic nuclei
Papenbrock, Thomas F.; Weidenmüller, H. A.
2015-09-03
Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. In this study, we extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. Lastly, in deformed nuclei these are vibrational modes each of which serves as band head of a rotational band.
Losa, C.; Doessing, T.; Pastore, A.; Vigezzi, E.; Broglia, R. A.
2010-06-15
We present a calculation of the properties of vibrational states in deformed, axially-symmetric even-even nuclei, within the framework of a fully self-consistent quasiparticle random phase approximation (QRPA). The same Skyrme energy density and density-dependent pairing functionals are used to calculate the mean field and the residual interaction in the particle-hole and particle-particle channels. We have tested our software in the case of spherical nuclei against fully self-consistent calculations published in the literature, finding excellent agreement. We investigate the consequences of neglecting the spin-orbit and Coulomb residual interactions in QRPA. Furthermore we discuss the improvement obtained in the QRPA result associated with the removal of spurious modes. Isoscalar and isovector responses in the deformed {sup 24-26}Mg, {sup 34}Mg isotopes are presented and compared to experimental findings.
Effective field theory of emergent symmetry breaking in deformed atomic nuclei
Papenbrock, Thomas F.; Weidenmüller, H. A.
2015-09-03
Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. In this study, we extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. Lastly, in deformed nuclei these are vibrational modes each of whichmore » serves as band head of a rotational band.« less
Gamow-Teller {beta}{sup +} decay of deformed nuclei near the proton drip line
Frisk, F.; Hamamoto, I.; Zhang, X.Z. |
1995-11-01
Using a quasiparticle Tamm-Dancoff approximation (TDA) based on deformed Hartree-Fock (HF) calculations with Skyrme interactions, the distribution of the Gamow-Teller (GT) {beta}{sup +} decay strength is estimated for the HF local minima of even-even deformed nuclei near the proton drip line in the region of 28{lt}{ital Z}{lt}66. The distribution often depends sensitively on the nuclear shape (namely, oblate or prolate). In the region of {ital Z}{lt}50 the possibility of observing {beta}-delayed proton emission depends sensitively on the excess of {ital Z} over {ital Z}={ital N}. In the region of {ital Z}{gt}50 almost the entire estimated GT strength is found to lie below the ground states of the even-even mother nuclei, and the observation of the total GT strength by {beta}-delayed charged-particle(s) emission will be of essential importance.
Proximity potential for deformed, oriented nuclei: 'Gentle' fusion and 'hugging' fusion
Manhas, Monika; Gupta, Raj K.
2005-08-01
The proximity potential is obtained in the form of the generalized 'pocket formula' for a collision between any two symmetric or asymmetric mass, deformed and noncoplanar (including also the case of coplanar) nuclei, having the fixed orientations {theta}{sub 1} and {theta}{sub 2} and any azimuthal angle {phi}(=0 deg. - 90 deg.). The method is applied first to some illustrative axially symmetric noncoplanar nuclei with the known 'gentle'- and 'hugging'-fusion configurations ({theta}{sub 1}={theta}{sub 2}=90 deg., {phi}=90 deg.). The very general case of noncoplanar nuclei having any orientation and azimuthal angles is also discussed. Application of the method to a specific reaction that has been used in experiments for synthesizing a superheavy nucleus is also made.
{sup 208}Pb-daughter cluster radioactivity and the deformations and orientations of nuclei
Arun, Sham K.; Gupta, Raj K.; Singh, BirBikram; Kanwar, Shefali; Sharma, Manoj K.
2009-06-15
The role of deformations and orientations of nuclei is studied for the first time in cluster decays of various radioactive nuclei, particularly those decaying to doubly closed shell, spherical {sup 208}Pb daughter nucleus. Also, the significance of using the correct Q-value of the decay process is pointed out. The model used is the preformed cluster model (PCM) of Gupta and collaborators [R. K. Gupta et al., Proc. Int. Conf. on Nuclear Reactions Mechanisms, Varenna, 1988, p. 416; Phys. Rev. C 39, 1992 (1989); 55, 218 (1997); Heavy Elements and Related New Phenomena, edited by W. Greiner and R. K. Gupta, World Sc. 1999, Vol. II, p. 731]. In this model, cluster emission is treated as a tunneling of the confining interaction barrier by a cluster considered already preformed with a relative probability P{sub 0}. Since both the scattering potential and potential energy surface due to the fragmentation process in the ground state of the parent nucleus change significantly with the inclusion of deformation and orientation effects, both the penetrability P and preformation probability P{sub 0} of clusters change accordingly. The calculated decay half-lives for all the cluster decays investigated here are generally in good agreement with measured values for the calculation performed with quadrupole deformations {beta}{sub 2} alone and 'optimum' orientations of cold elongated configurations. In some cases, particularly for {sup 14}C decay of Ra nuclei, the inclusion of multipole deformations up to hexadecapole {beta}{sub 4} is found to be essential for a comparison with data. However, the available {beta}{sub 4}-values, particularly for nuclei in the mass region 16{<=}A{<=}26, need be used with caution.
NASA Astrophysics Data System (ADS)
Ray, D.; Afanasjev, A. V.
2016-07-01
A systematic search for extremely deformed structures in the N ≈Z nuclei of the A ≈40 mass region has been performed for the first time in the framework of covariant density functional theory. At spin zero such structures are located at high excitation energies, which prevents their experimental observation. The rotation acts as a tool to bring these exotic shapes to the yrast line or its vicinity so that their observation could become possible with future generation of γ -tracking (or similar) detectors such as GRETA and AGATA. The major physical observables of such structures (such as transition quadrupole moments, as well as kinematic and dynamic moments of inertia), the underlying single-particle structure and the spins at which they become yrast or near yrast, are defined. The search for the fingerprints of clusterization and molecular structures is performed and the configurations with such features are discussed. The best candidates for observation of extremely deformed structures are identified. For several nuclei in this study (such as 36Ar), the addition of several spin units above the currently measured maximum spin of 16 ℏ will inevitably trigger the transition to hyper- and megadeformed nuclear shapes.
Deformed shell model results for neutrinoless double beta decay of nuclei in A = 60 - 90 region
NASA Astrophysics Data System (ADS)
Sahu, R.; Kota, V. K. B.
2015-03-01
Nuclear transition matrix elements (NTME) for the neutrinoless double beta decay (Oνββ or OνDBD) of 70Zn, 80Se and 82Se nuclei are calculated within the framework of the deformed shell model (DSM) based on Hartree-Fock (HF) states. For 70Zn, jj44b interaction in 2p3/2, 1f5/2, 2p1/2 and 1g9/2 space with 56Ni as the core is employed. However, for 80Se and 82Se nuclei, a modified Kuo interaction with the above core and model space are employed. Most of our calculations in this region were performed with this effective interaction. However, jj44b interaction has been found to be better for 70Zn. The above model space was used in many recent shell model (SM) and interacting boson model (IBM) calculations for nuclei in this region. After ensuring that DSM gives good description of the spectroscopic properties of low-lying levels in these three nuclei considered, the NTME are calculated. The deduced half-lives with these NTME, assuming neutrino mass is 1 eV, are 1.1 × 1026, 2.3 × 1027 and 2.2 × 1024 yr for 70Zn, 80Se and 82Se, respectively.
Octupole Deformation Bands of πh11/2 in Neutron-Rich 145,147La Nuclei
NASA Astrophysics Data System (ADS)
Zhu, Sheng-jiang; S, Zhu J.; Wang, Mu-ge; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; W, Ma C.; Long, Gui-lu; Zhu, Ling-yan; Li, Ming; A, Sakhaee; Gan, Cui-yun; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; Yu, Oganessian Ts; G, Ter-Akopian M.; A, Daniel V.
1999-03-01
Octupole deformation bands built on πh11/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the prompt γ-rays emitted from the 252Cf source. The alternating parity band structures and strong E1 transitions observed between negative- and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h11/2 single proton coupling. According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.
Skyrme random-phase-approximation description of lowest Kπ=2γ+ states in axially deformed nuclei
NASA Astrophysics Data System (ADS)
Nesterenko, V. O.; Kartavenko, V. G.; Kleinig, W.; Kvasil, J.; Repko, A.; Jolos, R. V.; Reinhard, P.-G.
2016-03-01
The lowest quadrupole γ -vibrational Kπ=2+ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies Eγ and reduced transition probabilities B (E 2 ) of 2γ+ states are calculated with the Skyrme forces SV-bas and SkM*. The energies of two-quasiparticle configurations forming the SRPA basis are corrected by using the pairing blocking effect. This results in a systematic downshift of Eγ by 0.3-0.5 MeV and thus in a better agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of Eγ and too weak collectivity of 2γ+ states still persist. It is shown that domains of nuclei with low and high 2γ+ collectivity are related to the structure of the lowest two-quasiparticle states and conservation of the Nilsson selection rules. The description of 2γ+ states with SV-bas and SkM* is similar in light rare-earth nuclei but deviates in heavier nuclei. However SV-bas much better reproduces the quadrupole deformation and energy of the isoscalar giant quadrupole resonance. The accuracy of SRPA is justified by comparison with exact RPA. The calculations suggest that a further development of the self-consistent calculation schemes is needed for a systematic satisfactory description of the 2γ+ states.
Probing resonances in deformed nuclei by using the complex-scaled Green's function method
NASA Astrophysics Data System (ADS)
Shi, Xin-Xing; Shi, Min; Niu, Zhong-Ming; Heng, Tai-Hua; Guo, Jian-You
2016-08-01
Resonance plays a key role in the formation of many physical phenomena. The complex-scaled Green's function method provides a powerful tool for exploring resonance. In this paper, we combine this method with the theory describing deformed nuclei with the formalism presented. Taking 45S as an example, we elaborate numerical details and demonstrate how to determine the resonance parameters. The results are compared with those obtained by the complex scaling method and the coupled-channel method and satisfactory agreement is obtained. In particular, the present scheme focuses on the advantages of the complex scaling method and the Green's function method and is more suitable for the exploration of resonance.
Charge-exchange QRPA with the Gogny Force for Axially-symmetric Deformed Nuclei
Martini, M.; Goriely, S.; Péru, S.
2014-06-15
In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the {sup 238}U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pnQRPA). In particular we focus on the Isobaric Analog and Gamow-Teller resonances. A comparison of the predicted GT strength distribution with existing experimental data is presented. The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist and for specific isotone chains of relevance for the r-process nucleosynthesis.
Interplay between proton-neutron pairing and deformation in self-conjugated medium mass nuclei
NASA Astrophysics Data System (ADS)
Gambacurta, Danilo; Lacroix, Denis
2016-05-01
We employ a model combining self-consistent mean-field and shell model techniques to study the competition between particle-like and proton-neutron pairing correlations in fp-shell even-even self-conjugate nuclei. Deformation effects are realistically and microscopically described. The resulting approach can give a precise description of pairing correlations and eventually treat the coexistence of different condensate formed of pairs with different total spin/ isospin. The standard BCS calculations are systematically compared with approaches including correlation effects beyond the independent quasi-particle picture. The competition between proton-neutron correlations in the isoscalar and isovector channels is also analyzed, as well as their dependence on the deformation properties.
Nobre, G. P. A.; Palumbo, A.; Herman, M.; Brown, D.; Hoblit, S.; Dietrich, F. S.
2015-02-25
The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, we have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elastic and inelastic angular distributions, are in reasonable agreement with measured experimental data. In conclusion, these results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.
Shape of Ar44: Onset of deformation in neutron-rich nuclei near Ca48
NASA Astrophysics Data System (ADS)
Zielińska, M.; Görgen, A.; Clément, E.; Delaroche, J.-P.; Girod, M.; Korten, W.; Bürger, A.; Catford, W.; Dossat, C.; Iwanicki, J.; Libert, J.; Ljungvall, J.; Napiorkowski, P. J.; Obertelli, A.; Piętak, D.; Rodríguez-Guzmán, R.; Sletten, G.; Srebrny, J.; Theisen, Ch.; Wrzosek, K.
2009-07-01
The development of deformation and shape coexistence in the vicinity of doubly magic Ca48, related to the weakening of the N=28 shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive Ar44 beam from the SPIRAL facility at GANIL. The 21+ and 22+ states in Ar44 were excited on Pb208 and Ag109 targets at two different beam energies. B(E2) values between all observed states and the spectroscopic quadrupole moment of the 21+ state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the Ar44 nucleus and giving evidence of an onset of deformation already two protons and two neutrons away from doubly magic Ca48. New Hartree-Fock-Bogoliubov based configuration mixing calculations have been performed with the Gogny D1S interaction for Ar44 and neighboring nuclei using two different approaches: the angular momentum projected generator coordinate method considering axial quadrupole deformations and a five-dimensional approach including the triaxial degree of freedom. The experimental values and new calculations are furthermore compared to shell-model calculations and to relativistic mean-field calculations. The new results give insight into the weakening of the N=28 shell closure and the development of deformation in this neutron-rich region of the nuclear chart.
Review of metastable states in heavy nuclei.
Dracoulis, G D; Walker, P M; Kondev, F G
2016-07-01
The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with [Formula: see text]. The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances. PMID:27243336
Review of metastable states in heavy nuclei
NASA Astrophysics Data System (ADS)
Dracoulis, G. D.; Walker, P. M.; Kondev, F. G.
2016-07-01
The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with A≳ 150 . The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances.
Non-Axial Octupole Deformations and Tetrahedral Symmetry in Heavy Nuclei
Mazurek, Katarzyna; Dudek, Jerzy
2005-11-21
The total energies of about 120 nuclei in the Thorium region have been calculated within the macroscopic-microscopic method in the 5-dimensional space of deformation parameters {alpha}20, {alpha}22, {alpha}30, {alpha}32 and {alpha}40. The macroscopic energy term contains the nuclear surface-curvature dependence as proposed within the LSD approach. The microscopic energies are calculated with the Woods-Saxon single particle potential employing the universal set of parameters.We study a possible presence of the octupole axial and non-axial degrees of freedom all-over in the ({beta}, {gamma})-plane focussing on the ground-states, secondary minima and in the saddle points. In fact, a competition between axial and tri-axial octupole deformation parameters is obtained at the saddle points and in the secondary minima for many isotones with N > 136. The presence of the tetrahedral symmetry minima is predicted in numerous nuclei in the discussed region, although most of the time at relatively high excitation energies.
Deformed rotational bands in the doubly odd nuclei [sup 134]Pr and [sup 132]Pr
Hauschild, K.; Wadsworth, R.; Clark, R.M.; Hibbert, I.M. ); Beausang, C.W.; Forbes, S.A.; Nolan, P.J.; Paul, E.S.; Semple, A.T.; Wilson, J.N. ); Gizon, A.; Gizon, J.; Santos, D. ); Simpson, J. )
1994-08-01
The nuclei [sup 132,134]Pr have been investigated using the [sup 100]Mo([sup 37]Cl,[ital xn]) reactions at a beam energy of 155 MeV. Gamma rays were detected with the Eurogam array. Analysis of the data has revealed the presence of two new weakly populated decoupled bands in [sup 134]Pr. One of these bands has been linked into the normal-deformed states and is thought to be built on a [pi]([ital h][sub 11/2])[sup 2][direct product][nu]([ital f][sub 7/2],[ital h][sub 9/2]) configuration. The second band has been interpreted as being based on a [pi]([ital h][sub 11/2])[sup 3][direct product][nu][ital i][sub 13/2] intruder configuration within the second [beta][sub 2][congruent]0.3 prolate minimum. The known decoupled band in [sup 132]Pr (5[ital n] reaction channel) and the highly deformed band in [sup 130]La A([alpha]3[ital n]) have also been extended. The structure of all of these bands is discussed together with similar bands in nieghboring odd-odd nuclei.
Fragmentation of two-phonon {gamma}-vibrational strength in deformed nuclei
Wu, C.Y.; Cline, D.
1996-12-31
Rotational and vibrational modes of collective motion. are very useful in classifying the low-lying excited states in deformed nuclei. The rotational mode of collective motion is characterized by rotational bands having correlated level energies and strongly-enhanced E2 matrix elements. The lowest intrinsic excitation with I,K{sup {pi}} = 2,2{sup +} in even-even deformed nuclei, typically occurring at {approx}1 MeV, is classified as a one-phonon {gamma}-vibration state. In a pure harmonic vibration limit, the expected two-phonon {gamma}-vibration states with I,K{sup {pi}} = 0,0{sup +} and 4,4{sup +} should have excitation energies at twice that of the I,K{sup {pi}} = 2,2{sup +} excitation, i.e. {approx}2 MeV, which usually is above the pairing gap leading to possible mixing with two-quasiparticle configurations. Therefore, the question of the localization of two-phonon {gamma}-vibration strength has been raised because mixing may lead to fragmentation of the two-phonon strength over a range of excitation energy. For several well-deformed nuclei, an assignment of I,K{sup {pi}}=4,4{sup +} states as being two-phonon vibrational excitations has been suggested based on the excitation energies and the predominant {gamma}-ray decay to the I,K{sup {pi}}=2,2{sup +} state. However, absolute B(E2) values connecting the presumed two- and one-phonon states are the only unambiguous measure of double phonon excitation. Such B(E2) data are available for {sup 156}Gd, {sup 160}Dy, {sup 168}Er, {sup 232}Th, and {sup 186,188,190,192}Os. Except for {sup 160}Dy, the measured B(E2) values range from 2-3 Weisskopf units in {sup 156}Gd to 10-20 Weisskopf units in osmium nuclei; enhancement that is consistent with collective modes of motion.
NASA Astrophysics Data System (ADS)
Agbemava, S. E.; Afanasjev, A. V.; Ring, P.
2016-04-01
A systematic investigation of octupole-deformed nuclei is presented for even-even systems with Z ≤106 located between the two-proton and two-neutron driplines. For this study we use five most-up-to-date covariant energy density functionals of different types, with a nonlinear meson coupling, with density-dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole-deformed nuclei. In addition, a detailed comparison with the predictions of nonrelativistic models is performed. A new region of octupole deformation, centered around Z ˜98 ,N ˜196 is predicted for the first time. In terms of its size in the (Z ,N ) plane and the impact of octupole deformation on binding energies this region is similar to the best known region of octupole-deformed nuclei centered at Z ˜90 ,N ˜136 . For the later island of octupole-deformed nuclei, the calculations suggest substantial increase of its size as compared with available experimental data.
Investigation of the Dipole Response in Exotic Nuclei --- Experiments at the LAND-R^3B Setup
NASA Astrophysics Data System (ADS)
Rossi, D.; Adrich, P.; Aksouh, F.; Alvarez-Pol, H.; Aumann, T.; Benlliure, J.; Böhmer, M.; Boretzky, K.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Pramanik, U. D.; Emling, H.; Ershova, O.; Fernando-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Johansson, H. k.; Junghans, A.; Kiselev, O.; Klimkiewicz, A.; Kratz, J.; Kurz, N.; Labiche, M.; Bleis, T. L.; Lemmon, R.; Litvinov, Y.; Mahata, K.; Maierbeck, P.; Movsesyan, A.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.
We present experimental results on the electromagneticexcitation of neutron-rich nickel isotopes, making use of the R^{3}B-LAND setup at GSI. Exotic beams were produced at approximately 500 MeV/u and their reactions were studied in inverse kinematics. Integral cross sections for ^{58}Ni are discussed and compared to previous data, providing a validation of our experimental method. The E1 excitation-energy distribution of the unstable ^{68}Ni is presented as well, showing an excess in cross section in the 1n decay channel when compared only with a typical Giant Dipole Resonance.
Effect of deformations on the binding energy of centrally depressed nuclei
NASA Astrophysics Data System (ADS)
Ismail, M.; Ellithi, A. Y.; Adel, A.; Abdulghany, A. R.
2015-07-01
The energy density formalism is implemented to study the binding energy of some heavy, superheavy and hyperheavy nuclei. The macroscopic contribution of binding energy is derived in the presence of a depression parameter in the nuclear density distribution, and the total energy is obtained by adding the shell and pairing correction to the macroscopic part. Total energy is studied with the variation of quadrupole {{β }2} and hexadecapole {{β }4} deformation parameters using different values of depression parameter. The addition of the shell and pairing corrections affects the behavior of the total energy especially the minimum position at specific deformation parameters, a second minimum in some cases are close to the first one, suggesting the possible existence of shape isomers. We minimized the total energy with respect to deformation and density depression parameters and obtained the binding energy of 208Pb, 238U, 252Cf, 280Cn, 285-289Fl, 298Fl, 306120, 320126, 339136, 500174 and 700226. The binding energies obtained are in good agreement with the available experimental data. The difference between the binding energies obtained by this simple method and experimental ones is less than 0.13%.
Deformation signature from the Gamow-Teller decay of N=Z nuclei
Miehe, Ch.; Dessagne, Ph.; Huck, A.; Knipper, A.; Marguier, G.; Longour, C.; Rauch, V.; Giovinazzo, J.; Borge, M. J. G.; Piqueras, I.; Tengblad, O.; Jokinen, A.; Ramdhane, M.
1998-12-21
The {sup 76}Sr (N=Z=38) and the {sup 72}Kr (N=Z=36) {beta}{sup +} EC decay have been studied at the CERN/ISOLDE PSB facility where their beta-gamma and delayed particle decay modes have been investigated. The established decay schemes yield new information on the Gamow-Teller (GT) strength spread over the J{sup {pi}}=1{sup +} states in the daughter nuclei. The delayed proton emission of an N=Z nucleus is observed for the first time in the case of {sup 76}Sr. The experimental GT strength intensities and distributions are discussed in the light of the theoretical estimates for oblate and prolate deformations.
Hoff, R.W.; Gardner, D.G.; Gardner, M.A.
1984-10-05
A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been used to construct sets of discrete states with energy 0 to 1.5 MeV in /sup 176/Lu and /sup 236/Np. These data were used as part of the input for calculation of isomer production cross-section ratios in the /sup 175/Lu(n,..gamma..)/sup 176/Lu and /sup 237/Np(n,2n)/sup 236/Np reactions. In order to achieve agreement with experiment, it has been found necessary to include in the modeled set many rotational bands (35 to 95), which are comprised of hundreds of levels with their gamma-ray branching ratios. It is essential that enough bands be included to produce a representative selection of K quantum numbers in the de-excitation cascade. 20 refs., 3 figs., 3 tabs.
Theory of (3He,(alpha)) surrogate reactions for deformed uranium nuclei
Thompson, I; Escher, J E
2006-11-08
We present the one-step theory of neutron-pickup transfer reactions with {sup 3}He projectiles on {sup 235}U and {sup 238}U. We find all the neutron eigenstates in a deformed potential, and use those in a given energy range for ({sup 3}He, {alpha}) DWBA pickup calculations to find the spin and parity distributions of the residual target nuclei. A simple smoothing convolution is used to take into account the spreading width of the single-neutron hole states into the more complicated compound nuclear states. We assume that the initial target is an even-even rotor, but can take into account spectator neutrons outside such a rotor by recombining their spin and parity at the end of the calculations.
Nobre, G. P. A.; Palumbo, A.; Herman, M.; Brown, D.; Hoblit, S.; Dietrich, F. S.
2015-02-25
The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, wemore » have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elastic and inelastic angular distributions, are in reasonable agreement with measured experimental data. In conclusion, these results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.« less
Beck, C.; Keeley, N.
2007-05-15
The influence on fusion of coupling to the breakup process is investigated for reactions where at least one of the colliding nuclei has a sufficiently low binding energy for breakup to become an important process. Elastic scattering, excitation functions for sub- and near-barrier fusion cross sections, and breakup yields are analyzed for {sup 6,7}Li+{sup 59}Co. Continuum-discretized coupled-channels (CDCC) calculations describe well the data at and above the barrier. Elastic scattering with {sup 6}Li (as compared to {sup 7}Li) indicates the significant role of breakup for weakly bound projectiles. A study of {sup 4,6}He induced fusion reactions with a three-body CDCC method for the {sup 6}He halo nucleus is presented. The relative importance of breakup and bound-state structure effects on total fusion is discussed.
NASA Astrophysics Data System (ADS)
Dickel, T.; Plaß, W. R.; Becker, A.; Czok, U.; Geissel, H.; Haettner, E.; Jesch, C.; Kinsel, W.; Petrick, M.; Scheidenberger, C.; Simon, A.; Yavor, M. I.
2015-03-01
A novel multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) and isobar separator for the research with exotic nuclides at low-energy rare isotope beam facilities has been developed, commissioned and characterized. It can be used (i) as broadband mass spectrometer with medium resolution, (ii) as highly accurate mass spectrometer for direct mass measurements and (iii) as high-resolution mass separator. The device features a worldwide unique combination of performance characteristics: a mass resolving power of 600,000 (FWHM), a mass measurement accuracy of ~10-7, large ion capacities in excess of 106 ions per second, a transmission efficiency of up to 70%, single-ion sensitivity, and cycle frequencies of up to 400 Hz have been achieved. The spatial separation of close-lying isobars with an intensity ratio of 200:1 and a binding energy difference as small as 4 MeV has been demonstrated. The MR-TOF-MS is ideally suited for experiments with rare and very short-lived nuclei at present and future in-flight, ISOL or IGISOL facilities, such as the FRS Ion-Catcher and SHIP/SHIPTRAP at GSI, TITAN at TRIUMF, IGISOL at the University of Jyväskylä and the Low-Energy Branch of the Super-FRS at FAIR.
NASA Astrophysics Data System (ADS)
Khoa, Dao Tien; Egelhof, Peter; Gales, Sydney; Giai, Nguyen Van; Motobayashi, Tohru
2008-04-01
]C([symbol], n)[symbol]O by the transfer reaction [symbol]C([symbol]Li, t)[symbol]O / F. Hammache et al. -- SPIRAL2 at GANIL: a world of leading ISOL facility for the physics of exotic nuclei / S. Gales -- Magnetic properties of light neutron-rich nuclei and shell evolution / T. Suzuki, T. Otsuka -- Multiple scattering effects in elastic and quasi free proton scattering from halo nuclei / R. Crespo et al. -- The dipole response of neutron halos and skins / T. Aumann -- Giant and pygmy resonances within axially-symmetric-deformed QRPA with the Gogny force / S. Péru, H. Goutte -- Soft K[symbol] = O+ modes unique to deformed neutron-rich unstable nuclei / K. Yoshida et al. -- Synthesis, decay properties, and identification of superheavy nuclei produced in [symbol]Ca-induced reactions / Yu. Ts. Oganessian et al. -- Highlights of the Brazilian RIB facility and its first results and hindrance of fusion cross section induced by [symbol]He / P. R. S. Gomes et al. -- Search for long fission times of super-heavy elements with Z = 114 / M. Morjean et al. -- Microscopic dynamics of shape coexistence phenomena around [symbol]Se and [symbol]Kr / N. Hinohara et al. -- [symbol]-cluster states and 4[symbol]-particle condensation in [symbol]O / Y. Funaki et al. -- Evolution of the N = 28 shell closure far from stability / O. Sorlin et al. -- Continuum QRPA approach and the surface di-neutron modes in nuclei near the neutron drip-line / M. Matsuo et al. -- Deformed relativistic Hartree-Bogoliubov model for exotic nuclei / S. G. Zhou et al. -- Two- and three-body correlations in three-body resonances and continuum states / K. Katō, K. Ikeda -- Pion- and Rho-Meson effects in relativistic Hartree-Fock and RPA / N. V. Giai et al. -- Study of the structure of neutron rich nuclei by using [symbol]-delayed neutron and gamma emission method / Y. Ye et al. -- Production of secondary radioactive [symbol] Na beam for the study of [symbol]Na([symbol], p)[symbol]Mg stellar reaction / D. N. Binh et al
NASA Astrophysics Data System (ADS)
Erhard, M.; Junghans, A. R.; Nair, C.; Schwengner, R.; Beyer, R.; Klug, J.; Kosev, K.; Wagner, A.; Grosse, E.
2010-03-01
Two methods based on bremsstrahlung were applied to the stable even Mo isotopes for the experimental determination of the photon strength function covering the high excitation energy range above 4 MeV with its increasing level density. Photon scattering was used up to the neutron separation energies Sn and data up to the maximum of the isovector giant resonance (GDR) were obtained by photoactivation. After a proper correction for multistep processes the observed quasicontinuous spectra of scattered photons show a remarkably good match to the photon strengths derived from nuclear photoeffect data obtained previously by neutron detection and corrected in absolute scale by using the new activation results. The combined data form an excellent basis to derive a shape dependence of the E1 strength in the even Mo isotopes with increasing deviation from the N=50 neutron shell (i.e., with the impact of quadrupole deformation and triaxiality). The wide energy coverage of the data allows for a stringent assessment of the dipole sum rule and a test of a novel parametrization developed previously which is based on it. This parametrization for the electric dipole strength function in nuclei with A>80 deviates significantly from prescriptions generally used previously. In astrophysical network calculations it may help to quantify the role the p-process plays in cosmic nucleosynthesis. It also has impact on the accurate analysis of neutron capture data of importance for future nuclear energy systems and waste transmutation.
Cao, X. G.; Zhang, G. Q.; Cai, X. Z.; Ma, Y. G.; Guo, W.; Chen, J. G.; Tian, W. D.; Fang, D. Q.; Wang, H. W.
2010-06-15
The reaction dynamics of axisymmetric deformed {sup 24}Mg+{sup 24}Mg collisions has been investigated systematically by an isospin-dependent quantum molecular dynamics model. It is found that different deformations and orientations result in apparently different properties of reaction dynamics. We reveal that some observables such as nuclear stopping power (R), multiplicity of fragments, and elliptic flow are very sensitive to the initial deformations and orientations. There exists an eccentricity scaling of elliptic flow in central body-body collisions with different deformations. In addition, the tip-tip and body-body configurations turn out to be two extreme cases in central reaction dynamical process.
NASA Astrophysics Data System (ADS)
Lisboa, R.; Malheiro, M.; Carlson, B. V.
2016-02-01
Background: Unbound single-particle states become important in determining the properties of a hot nucleus as its temperature increases. We present relativistic mean field (RMF) for hot nuclei considering not only the self-consistent temperature and density dependence of the self-consistent relativistic mean fields but also the vapor phase that takes into account the unbound nucleon states. Purpose: The temperature dependence of the pairing gaps, nuclear deformation, radii, binding energies, entropy, and caloric curves of spherical and deformed nuclei are obtained in self-consistent RMF calculations up to the limit of existence of the nucleus. Method: We perform Dirac-Hartree-Bogoliubov (DHB) calculations for hot nuclei using a zero-range approximation to the relativistic pairing interaction to calculate proton-proton and neutron-neutron pairing energies and gaps. A vapor subtraction procedure is used to account for unbound states and to remove long range Coulomb repulsion between the hot nucleus and the gas as well as the contribution of the external nucleon gas. Results: We show that p -p and n -n pairing gaps in the S10 channel vanish for low critical temperatures in the range Tcp≈0.6 -1.1 MeV for spherical nuclei such as 90Zr, 124Sn, and 140Ce and for both deformed nuclei 150Sm and 168Er. We found that superconducting phase transition occurs at Tcp=1.03 Δp p(0 ) for 90Zr, Tcp=1.16 Δp p(0 ) for 140Ce, Tcp=0.92 Δp p(0 ) for 150Sm, and Tcp=0.97 Δp p(0 ) for 168Er. The superfluidity phase transition occurs at Tcp=0.72 Δn n(0 ) for 124Sn, Tcp=1.22 Δn n(0 ) for 150Sm, and Tcp=1.13 Δn n(0 ) for 168Er. Thus, the nuclear superfluidity phase—at least for this channel—can only survive at very low nuclear temperatures and this phase transition (when the neutron gap vanishes) always occurs before the superconducting one, where the proton gap is zero. For deformed nuclei the nuclear deformation disappear at temperatures of about Tcs=2.0 -4.0 MeV , well above the
Sharipov, Sh.; Ermamatov, M. J. Bayimbetova, J. K.
2008-02-15
The properties of excited states of two deformable odd nuclei are investigated within the nonadiabatic model previously developed by the present authors. The results of relevant calculations are compared with available experimental data.
Lipkin, H.J.
1983-01-01
The question Are Anomalons Multiquark Exotics is discussed. It is concluded that so far there is no convincing experimental evidence for any multiquark exotic bound state nor for any exotic resonance. Except for the delta and S* there are no candidates for bound states and no firm theoretical predictions waiting to be tested. Exotic resonances may exist in the 1.5 to 2.0 GeV region and in the charmed sector, e.g., the charmed-strange exotics. The experimental search for multiquark resonances is still open and active. (WHK)
A C-code for the double folding interaction potential for reactions involving deformed target nuclei
NASA Astrophysics Data System (ADS)
Gontchar, I. I.; Chushnyakova, M. V.
2013-01-01
We present a C-code designed to obtain the interaction potential between a spherical projectile nucleus and an axial-symmetrical deformed target nucleus and in particular to find the Coulomb barrier, by using the double folding model (DFM). The program calculates the nucleus-nucleus potential as a function of the distance between the centers of mass of colliding nuclei as well as of the angle between the axis of symmetry of the target nucleus and the beam direction. The most important output parameters are the Coulomb barrier energy and the radius. Since many researchers use a Woods-Saxon profile for the nuclear term of the potential we provide an option in our code for fitting the DFM potential by such a profile near the barrier. Program summaryProgram title: DFMDEF Catalogue identifier: AENI_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENI_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2245 No. of bytes in distributed program, including test data, etc.: 215442 Distribution format: tar.gz Programming language: C. Computer: PC, Mac. Operating system: Windows XP (with the GCC-compiler version 2), MacOS, Linux. RAM: 100 MB with average parameters set Classification: 17.9. Nature of problem: The code calculates in a semimicroscopic way the bare interaction potential between a spherical projectile nucleus and a deformed but axially symmetric target nucleus as a function of the center of mass distance as well as of the angle between the axis of symmetry of the target nucleus and the beam direction. The height and the position of the Coulomb barrier are found. The calculated potential is approximated by a conventional Woods-Saxon profile near the barrier. Dependence of the barrier parameters upon the characteristics of the effective NN forces (like, e
Exotic Nuclei in South America
Lichtenthaeler, R.; Lepine-Szily, A.; Guimaraes, V.; Faria, P. N. de; Mendes, D. R. Jr; Pires, K. C. C.; Morcelle, V.; Barioni, A.; Morais, M. C.; Pampa Condori, R.; Assuncao, M.; Moro, A. M.; Rodriguez-Gallardo, M.; Arazi, A.
2010-08-04
The Radioactive Ion Beams in Brasil(RIBRAS) is described. Experiments using radioactive secondary beams of light rare isotopes such as {sup 6}He, {sup 7}Be, {sup 8}Li on several targets have been performed and the results are presented.
Zhang Yu; Pan Feng; Liu Yuxin; Luo Yanan; Draayer, J. P.
2011-09-15
An analytically solvable model, X(3/2j+1), is proposed to describe odd-A nuclei near the X(3) critical point. The model is constructed based on a collective core described by the X(3) critical point symmetry coupled to a spin-j particle. A detailed analysis of the spectral patterns for cases j=1/2 and j=3/2 is provided to illustrate dynamical features of the model. By comparing theory with experimental data and results of other models, it is found that the X(3/2j+1) model can be taken as a simple yet very effective scheme to describe those odd-A nuclei with an even-even core at the critical point of the spherical to axially deformed shape phase transition.
NASA Astrophysics Data System (ADS)
Sahu, R.; Srivastava, P. C.; Kota, V. K. B.
2013-09-01
Nuclear transition matrix elements (NTME) for neutrinoless positron double beta decay (0νβ+β+ and 0νβ+EC) of 64Zn, 74Se, 78Kr and 84Sr nuclei, which are in the A = 60-90 region, are calculated within the framework of the deformed shell model (DSM) based on Hartree-Fock states. For 64Zn, GXPF1A interaction in 1f7/2, 2p3/2, 1f5/2 and 2p1/2 space with 40Ca as the core is employed. Similarly for 74Se, 78Kr and 84Sr nuclei, 56Ni is taken as the inert core employing a modified Kuo interaction in 2p3/2, 1f5/2, 2p1/2 and 1g9/2 space. After ensuring that the DSM gives a good description of the spectroscopic properties of low-lying levels in the four nuclei considered, the NTME are calculated. The half-lives deduced with these NTME, assuming the neutrino mass is 1 eV, are smallest for 78Kr with the half-life for β+EC decay being ˜1027 yr. For all others, the half-lives are in the range of ˜1028-1029 yr.
NASA Astrophysics Data System (ADS)
Ni, Dongdong; Ren, Zhongzhou
2015-05-01
The weak-decay (β+ and EC) rates of neutron-deficient Kr, Sr, Zr, and Mo isotopes are investigated within the deformed quasiparticle random-phase approximation with realistic nucleon-nucleon interactions. The particle-particle and particle-hole channels of residual interactions are handled in large single-particle model spaces, based on the Brückner G-matrix with charge-dependent Bonn nucleon-nucleon forces. Contributions from allowed Gamow-Teller and Fermi transitions as well as first-forbidden transitions are calculated. The calculated half-lives show good agreement with the experimental data over a wide range of magnitude, from 10-2 to 107 s. Moreover, predictions of β-decay half-lives are made for some extremely proton-rich isotopes, which could be useful for future experiments.
NASA Astrophysics Data System (ADS)
Nayak, R. C.; Pattnaik, S.
2015-11-01
We identify here the possible occurrence of large deformations in the neutron- and proton-rich (n-rich and p-rich) regions of the nuclear chart from extensive predictions of the values of the reduced quadrupole transition probability B(E2)↑ for the transition from the ground state to the first 2+ state and the corresponding excitation energy E2 of even-even nuclei in the recently developed generalized differential equation (GDE) model exclusively meant for these physical quantities. This is made possible from our analysis of the predicted values of these two physical quantities and the corresponding deformation parameters derived from them such as the quadrupole deformation β2, the ratio of β2 to the Weisskopf single-particle β2(sp) and the intrinsic electric quadrupole moment Q0, calculated for a large number of both known as well as hitherto unknown even-even isotopes of oxygen to fermium (0 to FM; Z = 8-100). Our critical analysis of the resulting data convincingly support possible existence of large collectivity for the nuclides 30,32Ne,34Mg, 60Ti, 42,62,64Cr,50,68Fe, 52,72Ni, 72,70,96Kr,74,76Sr,78,80,106,108Zr, 82,84,110,112Mo, 140Te,144Xe, 148Ba,122Ce, 128,156Nd,130,132,158,160Sm and 138,162,164,166Gd, whose values of β2 are found to exceed 0.3 and even 0.4 in some cases. Our findings of large deformations in the exotic n-rich regions support the existence of another “island of inversion” in the heavy-mass region possibly caused by breaking of the N = 70 subshell closure.
Effects of angular dependence of surface diffuseness in deformed nuclei on Coulomb barrier
NASA Astrophysics Data System (ADS)
Adamian, G. G.; Antonenko, N. V.; Malov, L. A.; Scamps, G.; Lacroix, D.
2014-09-01
The angular dependence of surface diffuseness is further discussed. The results of self-consistent calculations are compared with those obtained with the phenomenological mean-field potential. The rather simple parametrizations are suggested. The effects of surface polarization and hexadecapole deformation on the height of the Coulomb barrier are revealed.
Zhang Yu; Pan Feng; Liu Yuxin; Hou Zhanfeng; Draayer, J. P.
2010-09-15
A coupling scheme for even-even nuclei with the X(5) critical point symmetry coupled to a single valence nucleon in a j orbit is proposed to approximately describe the critical point phenomena of spherical to axially deformed shape (phase) transition in odd-A nuclear systems. The corresponding scheme, which can be solved analytically, is called the X(5/(2j+1)) model. A special case with j=1/2 is analyzed in detail to show its level structure and transition patterns. It is further shown that {sup 189}Au and {sup 155}Tb may be possible X(5/(2j+1)) symmetry candidates with j=1/2 and j=3/2, respectively.
NASA Astrophysics Data System (ADS)
Ring, P.; Gambhir, Y. K.; Lalazissis, G. A.
1997-09-01
We present a Fortran program for the calculation of the ground state properties of axially deformed even-even nuclei in the framework of Relativistic Mean Field Theory (RMF). In this approach a set of coupled partial differentials has to be solved self-consistently: the Dirac equation for the nucleons moving in self-consistent fields and the Klein-Gordon equations for the meson fields and the electromagnetic field, whose sources are scalar and vector densities determined of the nucleons. For this purpose the Dirac spinors as well as the meson fields are expanded in terms of anisotropic oscillator wave functions in cylindrical coordinates. This requires a matrix diagonalization for the solution of the Dirac equations and the solution of an inhomogeneous matrix equation for the meson fields. For the determination of the Coulomb field the Greens function method is used.
Kuzyakin, R. A. Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.
2013-06-15
Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the {sup 16}O + {sup 112}Cd, {sup 152}Sm, and {sup 184}W; {sup 19}F +{sup 175}Lu; {sup 28}Si +{sup 94,100}Mo and {sup 154}Sm; {sup 40}Ca +{sup 96}Zr; {sup 48}Ca+ {sup 90}Zr; and {sup 64}Ni +{sup 58,64}Ni, {sup 92,96}Zr, and {sup 100}Mo reactions are in good agreement with available experimental data.
NASA Astrophysics Data System (ADS)
Kuzyakin, R. A.; Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.
2013-06-01
Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the 16O + 112Cd, 152Sm, and 184W; 19F +175Lu; 28Si +94,100Mo and 154Sm; 40Ca +96Zr; 48Ca+ 90Zr; and 64Ni +58,64Ni, 92,96Zr, and 100Mo reactions are in good agreement with available experimental data.
Dominance of Low Spin and High Deformation in Ab Initio Approaches to the Structure of Light Nuclei
Dytrych, T.; Draayer, J. P.; Sviratcheva, K. D.; Bahri, C.; Vary, J. P.
2009-08-26
Ab initio no-core shell-model solutions for the structure of light nuclei are shown to be dominated by low-spin and high-deformation configurations. This implies that only a small fraction of the full model space is important for a description of bound-state properties of light nuclei. It further points to the fact that the coupling scheme of choice for carrying out calculations for light nuclear systems is an algebraic-based, no-core shell-model scheme that builds upon an LS coupling [SO(3) x SU(2)] foundation with the spatial part of the model space further organized into its symplectic [SO(3) subset of SU(3) subset of Sp(3, R)] structure. Results for {sup 12}C and {sup 16}O are presented with the cluster nature of the excited 0{sup +} states in {sup 16}O analyzed within this framework. The results of the analysis encourages the development of a no-core shell model code that takes advantage of algebraic methods as well as modern computational techniques. Indeed, although it is often a very challenging task to cast complex algebraic constructs into simple logical ones that execute efficiently on modern computational systems, the construction of such a next-generation code is currently underway.
Proton emission from the deformed odd-odd nuclei near drip line
NASA Astrophysics Data System (ADS)
Patial, M.; Arumugam, P.; Jain, A. K.; Maglione, E.; Ferreira, L. S.
2016-01-01
Proton emission from odd-odd nuclei is studied within the two quasiparticle plus rotor model which includes the non-adiabatic effects and the residual interaction between valence proton and neutron. Justification of the formalism is discussed through corroboration of our results with the experimental spectrum of 180Ta. Exact calculations are performed to get the proton emission halflives. Our results for the proton emitter 130Eu leads to the assignment of spin and parity Jπ = 1+ for the ground state. The role of Coriolis and residual neutron-proton interactions on the proton emission halflives and their interplay are also discussed.
NASA Astrophysics Data System (ADS)
Li, Dong-Peng; Chen, Shou-Wan; Niu, Zhong-Ming; Liu, Quan; Guo, Jian-You
2015-02-01
Following a recent letter [J.-Y. Guo, S.-W. Chen, Z.-M. Niu, D.-P. Li, and Q. Liu, Phys. Rev. Lett. 112, 062502 (2014), 10.1103/PhysRevLett.112.062502], we present more details for the relativistic symmetry research by using the similarity renormalization group. With the theoretical formalism expressed in detail, we explore the origin and breaking mechanism of relativistic symmetries for an axially deformed nucleus. By comparing the energy splitting between the (pseudo-) spin doublets, it is shown that the spin energy splitting arises almost completely from the spin-orbit coupling, while the pseudospin energy splitting arises from a combination of the nonrelativistic, dynamical, and spin-orbit terms. Furthermore, these splittings are correlated with nuclear deformation as well as with the quantum numbers of the doublets. The origin of relativistic symmetries is disclosed and the breaking mechanism of spin and pseudospin symmetries is clarified.
Interplay between tensor force and deformation in even-even nuclei
NASA Astrophysics Data System (ADS)
Bernard, Rémi N.; Anguiano, Marta
2016-09-01
In this work we study the effect of the nuclear tensor force on properties related with deformation. We focus on isotopes in the Mg, Si, S, Ar, Sr and Zr chains within the Hartree-Fock-Bogoliubov theory using the D1ST2a Gogny interaction. Contributions to the tensor energy in terms of saturated and unsaturated subshells are analyzed. Like-particle and proton-neutron parts of the tensor term are independently examinated. We found that the tensor term may considerably modify the potential energy landscapes and change the ground state shape. We analyze too how the pairing characteristics of the ground state change when the tensor force is included.
Selection rules for electromagnetic transitions in triaxially deformed odd-A nuclei
Tanabe, Kosai; Sugawara-Tanabe, Kazuko
2008-06-15
The approximate selection rules for the interband and intraband electromagnetic transitions are predicted referring to two quantum numbers, which are derived from an algebraic solution for the particle-rotor model with one high-j nucleon coupled to a triaxially deformed core. It is shown that the inclusion of angular momentum dependence for moments of inertia reproduces the experimental excitation energies relative to a reference quite well both for positive and negative parity TSD bands in {sup 161,163,165,167}Lu.
Deformation increase of high-spin core-excited isomers in the astatine nuclei
Scheveneels, G.; Hardeman, F.; Neyens, G.; Coussement, R. )
1991-06-01
Quadrupole moments of six high-spin isomers in the At isotopes have been measured with the level-mixing-spectroscopy method: {sup 208}At(16{sup {minus}}), {sup 209}At(29/2{sup +}), {sup 210}At(19{sup +},15{sup {minus}}), {sup 211}At(39/2{sup {minus}},29/2{sup +}). The results show that level mixing spectroscopy is a promising technique to determine quadrupole moments of isomers that are difficult to measure by other in-beam hyperfine interaction methods. A large increase of the quadrupole moment is observed if neutrons are excited across or removed from the {ital N}=126 shell closure. This behavior is explained in terms of an enhanced core softness for fewer core neutrons; the aligned valence particles, moving in equatorial orbits, then easily polarize the core towards oblate deformation.
Charge-exchange modes of excitation in deformed neutron-rich nuclei
Yoshida, Kenichi
2015-10-15
Gamow-Teller (GT) mode of excitation and β-decay properties of deformed neutron-rich even-N Zr isotopes are investigated in a self-consistent Skyrme energy-density-functional approach, in which the Hartree-Fock-Bogoliubov equation is solved in the coordinate space and the proton-neutron Quasiparticle-RPA equation is solved in the quasiparticle basis. It is found that a stronger collectivity is generated for the GT giant resonance as an increase in the neutron number. Furthermore, we find that the T = 0 pairing enhances the low-lying GT strengths cooperatively with the T = 1 pairing correlation depending on the microscopic structure of the low-lying mode and the shell structure around the Fermi levels, and that the enhanced strength shortens the β-decay half-lives by at most an order of magnitude.
Shape phase transition in odd-even nuclei: From spherical to deformed gamma-unstable shapes
Boeyuekata, M.; Alonso, C. E.; Arias, J. M.; Fortunato, L.; Vitturi, A.
2010-07-15
Shape phase transitions in odd-A nuclei are investigated within the framework of the interacting boson-fermion model. The case of a single j=9/2 fermion coupled to an even-even boson core is considered. This boson core transits from spherical to gamma-unstable shapes depending on the value of a control parameter in the boson Hamiltonian. The effect of the coupling of the odd particle to this core along the shape transition and, in particular, at the critical point is discussed. For that purpose, the ground-state energy surface in terms of the beta and gamma shape variables for the even core and odd-even energy surfaces for the different K states coming from j=9/2 are constructed. The evolution of each individual coupled state along the transition from the spherical [U(5)] to the gamma-unstable [O(6)] situation is investigated. One finds that the core-fermion coupling gives rise to a smoother transition than in the even-core case.
NASA Astrophysics Data System (ADS)
Nabi, Jameel-Un; Böyükata, Mahmut
2016-03-01
We investigate even-even nuclei in the A ∼ 70 mass region within the framework of the proton-neutron quasi-particle random phase approximation (pn-QRPA) and the interacting boson model-1 (IBM-1). Our work includes calculation of the energy spectra and the potential energy surfaces V (β , γ) of Zn, Ge, Se, Kr and Sr nuclei with the same proton and neutron number, N = Z. The parametrization of the IBM-1 Hamiltonian was performed for the calculation of the energy levels in the ground state bands. Geometric shape of the nuclei was predicted by plotting the potential energy surfaces V (β , γ) obtained from the IBM-1 Hamiltonian in the classical limit. The pn-QRPA model was later used to compute half-lives of the neutron-deficient nuclei which were found to be in very good agreement with the measured ones. The pn-QRPA model was also used to calculate the Gamow-Teller strength distributions and was found to be in decent agreement with the measured data. We further calculate the electron capture and positron decay rates for these N = Z waiting point (WP) nuclei in the stellar environment employing the pn-QRPA model. For the rp-process conditions, our total weak rates are within a factor two compared with the Skyrme HF +BCS +QRPA calculation. All calculated electron capture rates are comparable to the competing positron decay rates under rp-process conditions. Our study confirms the finding that electron capture rates form an integral part of the weak rates under rp-process conditions and should not be neglected in the nuclear network calculations.
NASA Astrophysics Data System (ADS)
Casten, R. F.; Cakirli, R. B.
2009-03-01
Understanding the development of configuration mixing, coherence, collectivity, and deformation in nuclei is one of the crucial challenges in nuclear structure physics, and one which has become all the more important with the advent of next generation facilities for the study of exotic nuclei. We will discuss recent work on phase/shape transitional behavior in nuclei, and the role of changes in sub-shell structure in mediating such transitional regions. We will also discuss a newly found, much deeper, link between nuclear structure and nuclear binding energies.
NASA Astrophysics Data System (ADS)
Yakut, H.; Guliyev, E.; Guner, M.; Tabar, E.; Zenginerler, Z.
2012-08-01
A new microscopic method has been developed in the framework of the Quasiparticle-Phonon Nuclear Model (QPNM) in order to investigate spin polarization effects on the magnetic properties such as magnetic moment, intrinsic magnetic moment and effective gs factor of the ground state of odd-mass 157-167Er isotopes. The calculations were performed using both Tamm-Dancoff Approximation (TDA) and Quasiparticle Random-Phase Approximation (QRPA). Reasonably good agreement has been obtained between the QRPA results and the relevant experimental data. Furthermore the variation of the intrinsic magnetic moment gK values with the mass number A exhibits similar behavior for both theoretical and experimental results. From the compression of the calculated intrinsic magnetic moment values with the experimental data the spin-spin interaction parameter has been found as χ=(30/A) MeV for odd-mass 157-167Er isotopes. Our results clarify the possibility of using this new method to describe the magnetic properties of odd-mass deformed nuclei.
NASA Astrophysics Data System (ADS)
Khouaja, A.; Villari, A. C. C.; Benjelloun, M.; Hirata, D.; Savajols; Mittig, W.; Roussel-Chomaz, P.; Orr, N. A.; Pita, S.; Demonchy, C. E.; Giot, L.; Chartier, M.; Gillibert, A.; Baiborodin, D.; Penionzhkevich, Y.; Catford, W. N.; Lépine-Szily, A.; Dlouhy, Z.
2005-09-01
Mean energy integrated reaction cross-section measurements for various neutron-rich nuclei covering the region of closed shells N=20 and N=28 were performed, at intermediate energy (30 - 65 A.MeV), via direct method, where the Silicon detectors are used as an active target. Assuming that the energy dependence of the reaction cross-section is well described by the parametrization of S.Kox, the reduced strong absorption radius r02 is extracted for the first time, for 19 new nuclei, i.e. 27F, 27,30Ne, 33Na, 28,34-35Mg, 36-38Al, 38-40Si, 41-42P, 42-44S, 45Cl. Other 60 radii also measured in this experiment are compared to results from literature. The evolution of the reduced strong absorption radius is studied as a function of the neutrons excess. A new quadratic parametrization is therefore proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. According to this parametrization, the skin effect is well reproduced and anomalous behaviours are observed to the nuclei 23N, 29Ne, 33Na, 35Mg, 44S, 45Cl and 45Ar.
Luo, W.D.; Bouguettoucha, A.; Dobaczewski, J.; Dudek, J.; Li, X.
1995-12-01
Microscopic analysis of the quantum (shell) effects related to the presence of the hexadecapole ({ital Y}{sub 4{mu}}; {mu}=0,2,4) components in the nuclear mean field is performed for the superdeformed nuclei in the mass {ital A} {similar_to} 150 region using the deformed Woods-Saxon potential. No shell effects favoring the {ital C}{sub 4}-symmetry are found. The calculations indicate, however, the existence of the {alpha}{sub 44}-deformation driving orbitals whose occupation might induce an {alpha}{sub 44}-polarization effect. For {sup 149}Gd and {sup 153}Dy nuclei, in which the existence of the {ital C}{sub 4}-symmetry effects is suspected, properties of several excited particle-hole configuration are analyzed.
NASA Astrophysics Data System (ADS)
Koh, Meng-Hock; Duy Duc, Dao; Nhan Hao, T. V.; Thuy Long, Ha; Quentin, P.; Bonneau, L.
2016-01-01
In four well-deformed heavy odd nuclei, the energies of low-lying rotational band heads have been determined microscopically within a self-consistent Hartree-Fock-plus-BCS approach with blocking. A Skyrme nucleon-nucleon effective interaction has been used together with a seniority force to describe pairing correlations. Only such states which are phenomenologically deemed to be related to single-particle excitations have been considered. The polarization effects, including those associated with the genuine time-reversal symmetry breaking have been fully taken into account within our model assumptions. The calculated spectra are in reasonably good qualitative agreement with available data for the considered odd-neutron nuclei. This is not so much the case for the odd-proton nuclei. A potential explanation for such a difference in behavior is proposed.
Coello Pérez, Eduardo A.; Papenbrock, Thomas F.
2015-07-27
In this paper, we present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoreticalmore » uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. In addition, we study the faint interband transitions within the effective theory and focus on the E2 transitions from the 02+ band (the “β band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.« less
Coello Pérez, Eduardo A.; Papenbrock, Thomas F.
2015-07-27
In this paper, we present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoretical uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. In addition, we study the faint interband transitions within the effective theory and focus on the E2 transitions from the 0_{2}^{+} band (the “β band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.
Ross, T.J.; Hughes, R.O.; Beausang, C.W.; Allmond, James M; Angell, C.T.; Basunia, M.S.; Bleuel, D.L.; Burke, J.T.; Casperson, R.J.; Escher, J.E.; Fallon, P.; Hatarik, R.; Munson, J.; Paschalis, S.; Petri, M.; Phair, L.; Ressler, J.J.; Scielzo, N.D.
2013-01-01
Odd-mass gadolinium isotopes around N = 90 were populated by the (p,d ) reaction, utilizing 25-MeV protons, resulting in population of low-spin quasineutron states at energies near and below the Fermi surface. Systematics of the single quasineutron levels populated are presented. A large excitation energy gap is observed between levels originating from the 2d3/2 , 1h11/2 , and 3s1/2 spherical parents (above the N = 64 gap), and the 2d5/2 (below the gap), indicating that the spherical shell model level spacing is maintained at least to moderate deformations.
NASA Astrophysics Data System (ADS)
Samarin, Viacheslav
2014-03-01
Time-dependent Schrödinger equation is numerically solved by difference method for external neutrons of nuclei 6He, 18O, 48Са, 238U at their grazing collisions with energies in the vicinity of a Coulomb barrier. The spin-orbital interaction and Pauli's exclusion principle were taken into consideration during the solution.
Pauling, L
1982-11-01
A set of rules, involving the magic and semimagic values of neutron and proton numbers and the proton/neutron ratio, is formulated for the composition of the revolving clusters producing the values of the moment of inertia given by the differences in energy of the adjacent levels in quasibands and bands of nuclei. The cluster compositions assigned with use of these rules to isotopes of Kr, Sr, Zr, Mo, and the actinon nuclei and to successive levels of the ground-state band of (158)Er lead to reasonable values of the radius of revolution (the distance from the center of the nonrevolving sphere to the center of the cluster). These values correspond to a spheron diameter of about 3.20 fm. PMID:16593256
Hoff, R.W.; Jain, A.K.; Kvasil, J.; Sood, P.C.; Sheline, R.K.; Florida State Univ., Tallahassee, FL )
1989-09-01
The application of a simple semi-empirical model is discussed in terms of interpreting experimental nuclear structure data for twelve of the best characterized odd-odd deformed nuclei. An essential part of this modeling is to calculate values for the Gallagher-Moszkowski splittings and Newby shifts, the observables that arise from the n-p residual interaction in odd-odd nuclei. Assumptions regarding the form for this n-p force are traced historically. The predictive power of a favored form of the n-p force, one that includes a central force with short and long-range components, a tensor force, and some effects of core polarization, is examined in light of experimental data obtained since its formulation. A data set of 42 experimentally determined Newby shifts has been reviewed as to the reliability of each entry. Exceptions to a recently proposed rule for the a priori determination of the sign of Newby shift are discussed. Evidence is presented for the existence of an odd-even staggering or signature effect in the rotational spacings of many K{sup {minus}} bands (with K > 0). By use of Coriolis-coupling calculations, it has been possible to reproduce the staggering observed in some of the K{sup {minus}} rotational bands of {sup 156}Tb, {sup 168}Tm, {sup 176}Lu, {sup 182}Ta, and {sup 182}Re. 27 refs., 3 figs., 3 tabs.
Probing the maximally deformed light rare-earth region around the drip-line nucleus 130Sm
NASA Astrophysics Data System (ADS)
Petri, M.; Paul, E. S.; Nolan, P. J.; Boston, A. J.; Cooper, R. J.; Dimmock, M. R.; Gros, S.; McGuirk, B. M.; Scraggs, H. C.; Turk, G.; Rossé, B.; Meyer, M.; Redon, N.; Schmitt, Ch; Stézowski, O.; Guinet, D.; Lautesse, Ph; DeFrance, G.; Bhattachasyya, S.; Mukherjee, G.; Rejmund, F.; Rejmund, M.; Savajols, H.; Scheurer, J. N.; Astier, A.; Deloncle, I.; Prévost, A.; Nyakó, B. M.; Gál, J.; Molnár, J.; Timár, J.; Zolnai, L.; Juhász, K.; Pucknell, V. F. E.; Wadsworth, R.; Joshi, P.; La Rana, G.; Moro, R.; Trotta, M.; Vardaci, E.; Hackman, G.; Ball, G.
2006-07-01
The neutron deficient rare-earth nuclei of the A~130 region are of particular interest since highly deformed prolate ground states are expected. Indeed these nuclei are predicted to show maximal ground-state deformations of β2 ~ 0.40 (axis ratio of 3:2), comparable to the deformation deduced for superdeformed cerium isotopes at high spin. A fusion-evaporation experiment was performed with radioactive ion beams at GANIL in October 2004 which had the goal to reach very proton-rich exotic nuclei located near the proton drip-line. A radioactive 76Kr beam, delivered by the SPIRAL facility, was used to bombard a thin 58Ni target. Emitted γ-rays were detected by the EXOGAM γ-ray spectrometer which was, for the first time, coupled with both the DIAMANT charged-particle array and the VAMOS spectrometer.
Description of superdeformed nuclei in the A{approx}190 region by generalized deformed su{sub q}(2)
Alharbi, H. H.; Alhendi, H. A.; Alhakami, F. S.
2009-05-15
The generalized deformed su{sub q}(2) model is applied to 79 superdeformed bands in the region A{approx}190. The transition energies and the moments of inertia are calculated within the model and their validity is investigated by comparing them with the experimental data. Both the standard su{sub q}(2) and the generalized one fail to account for the uprising and the downturn of the dynamic moments of inertia. Both models, however, show remarkable agreement with the available experimental data at low angular frequency (({Dirac_h}/2{pi}){omega}{<=}0.25 MeV)
Nonaxial-octupole effect in superheavy nuclei
Chen, Y.-S.; Sun, Yang; Gao Zaochun
2008-06-15
The triaxial-octupole Y{sub 32} correlation in atomic nuclei has long been expected to exist but experimental evidence has not been clear. We find, in order to explain the very low-lying 2{sup -} bands in the transfermium mass region, that this exotic effect may manifest itself in superheavy elements. Favorable conditions for producing triaxial-octupole correlations are shown to be present in the deformed single-particle spectrum, which is further supported by quantitative Reflection Asymmetric Shell Model calculations. It is predicted that the strong nonaxial-octupole effect may persist up to the element 108. Our result thus represents the first concrete example of spontaneous breaking of both axial and reflection symmetries in the heaviest nuclear systems.
Light exotic systems at relativistic velocities
NASA Astrophysics Data System (ADS)
Simon, H.
2010-03-01
In this paper the results of a series of experiments, carried out at the GSI accelerator facilities in Darmstadt at the Aladin-LAND reaction setup are presented. Light nuclei at relativistic velocities, impinging on a carbon and a liquid hydrogen reaction target break up and all fragments are detected in coincidence. The observed correlations are used to draw conclusions on the underlying structure of the bound exotic projectiles as well as to explore continuum structures.
Exotic structures near the drip lines
Sharma, M. M.; Saldanha, A. A.; Sharma, J. K.
2011-10-28
In our recent study of the isotope shifts of Kr isotopes near rp-process path in the framework of the RMF theory, we have found that due to large shell gaps in the deformed space, several N = Z nuclei exhibit the double magicity of protons and neutrons. These nuclei are known to contribute to large abundances in the rp-process nucleosynthesis and have been shown to be the waiting-point nuclei. In another study of the shell effects at N = 126 near the neutron drip line, we have found that nuclei exhibit additional stability beyond the neutron drip line.
Effective Theory for Deformed Nuclei
Papenbrock, Thomas F
2011-01-01
Techniques from effective field theory are applied to nuclear rotation. This approach exploits the spontaneous breaking of rotational symmetry and the separation of scale between low-energy Nambu-Goldstone rotational modes and high-energy vibrational and nucleonic degrees of freedom.
The influence of microscopic structures on rotational motion in nuclei
NASA Astrophysics Data System (ADS)
Wadsworth, R.; Nolan, P. J.
2002-07-01
This paper will concentrate on a study of the role and influence of microscopic structures on the properties of rotational bands in nuclei. Collective rotational features are well known in nuclei. Much of the review will discuss examples taken from experimental investigations of highly/superdeformed structures and their theoretical interpretation, which provide some of best and clearest rotational phenomena observed in nuclei. These structures have well-defined rotational properties that can be described by a collective model. The link between the deformation of these structures and the valence particle configuration has been established in many nuclei and recent experimental data are presented. Detailed investigations with new, very sensitive, instrumentation have revealed some extremely interesting and unexpected phenomena, such as the observation of identical rotational bands in neighbouring nuclei and energy staggering between adjacent states within a single band. The experimental and theoretical aspects of these new features will be discussed. The spectroscopy of highly/superdeformed structures has been studied extensively and many bands observed in a given nucleus which arise from particle-hole excitations. Measurements are now available, through the strength of magnetic dipole transitions, of the properties of specific single-particle orbitals. In the medium mass (A~60) region highly deformed states have been observed to decay by both proton and alpha emission in addition to the normal γ-decay mode. The decay widths, which are retarded for these channels, are related to the microscopic structures of the states involved. Investigations of rotational motion in exotic triaxial and hyperdeformed nuclear shapes are also reviewed. Recent work on `smooth band termination', in medium to medium-heavy nuclei, which results when a deformed collectively rotating nucleus gradually changes from a near-prolate to a non-collective oblate shape, has revealed detailed
NASA Astrophysics Data System (ADS)
Mishra, S.; Shukla, A.; Sahu, R.; Kota, V. K. B.
2008-08-01
The β+/EC half-lives of medium heavy N~Z nuclei with mass number A~64-80 are calculated within the deformed shell model (DSM) based on Hartree-Fock states by employing a modified Kuo interaction in (2p3/2,1f5/2,2p1/2,1g9/2) space. The DSM model has been quite successful in predicting many spectroscopic properties of N~Z medium heavy nuclei with A~64-80. The calculated β+/EC half-lives, for prolate and oblate shapes, compare well with the predictions of the calculations with Skyrme force by Sarriguren Going further, following recent searches, half-lives for 2ν β+β+/β+EC/ECEC decay for the nucleus Kr78 are calculated using DSM and the results compare well with QRPA predictions.
Utsuno, Yutaka; Otsuka, Takaharu; Brown, B. Alex; Honma, Michio; Mizusaki, Takahiro
2011-05-06
The structure of exotic nuclei around N = 28 is investigated in the sd-pf shell-model space using a new effective interaction. The cross-shell part of the interaction is provided by the monopole-based universal interaction which has been successful in accounting for single-particle evolution in several mass regions. Focusing on the nuclear structure that is sensitive to the shell evolution, we show successful results for the proton-hole states in K isotopes and large deformation in {sup 42}Si. The results demonstrate that the present scheme may be a promising way for constructing an effective interaction for other mass regions.
Nuclear spectroscopy in nuclei with Z ≥ 110
NASA Astrophysics Data System (ADS)
Ackermann, D.
2015-12-01
The nuclear structure of species at the extreme of highest atomic numbers Z and nuclear masses A promises to reveal intriguing new features of this exotic hadronic matter. Their stability itself they owe to quantum-mechanic effects only. They form metastable states which, governed by the subtle interplay of α decay and spontaneous fission versus quantum-mechanic stabilization via shell effects, are in some cases more robust against disintegration than their ground states. Following the isotopic and isotonic trends of single particle levels, as well as collective features like deformation, may reveal the path towards the gap in the level densities, expected for the next closed proton and neutron shells at the so-called "island of stability" of spherical superheavy nuclei. Their atomic configuration offers via X-ray spectroscopy a tool to identify the atomic number of heavy species, where other more traditional methods like evaporation residue (ER)-α correlation are not applicable.
Casalbuoni, Roberto; Gomis, Joaquim; Longhi, Giorgio
2007-12-15
We construct a classical nonrelativistic string model in 3+1 dimensions. The model contains a spurion tensor field that is responsible for the noncommutative structure of the model. Under double-dimensional reduction the model reduces to the exotic nonrelativistic particle in 2+1 dimensions.
Exotic branes and nongeometric backgrounds.
de Boer, Jan; Shigemori, Masaki
2010-06-25
When string or M theory is compactified to lower dimensions, the U-duality symmetry predicts so-called exotic branes whose higher-dimensional origin cannot be explained by the standard string or M-theory branes. We argue that exotic branes can be understood in higher dimensions as nongeometric backgrounds or U folds, and that they are important for the physics of systems which originally contain no exotic charges, since the supertube effect generically produces such exotic charges. We discuss the implications of exotic backgrounds for black hole microstate (non-)geometries. PMID:20867363
Superheavy nuclei and fission barriers
NASA Astrophysics Data System (ADS)
Lu, Bing-Nan; Zhao, Jie; Zhao, En-Guang; Zhou, Shan-Gui
In this chapter, we will present relativistic mean field (RMF) description of heavy and superheavy nuclei (SHN). We will discuss the shell structure and magic numbers in the mass region of SHN, binding energies and α decay Q values, shapes of ground states and potential energy surfaces and fission barriers. We particularly focus on the multidimensionally-constrained covariant density functional theories (CDFT) and the applications of CDFT to the study of exotic nuclear shapes and fission barriers.
Promoting the exotic pet practice.
Harris, Don J
2005-09-01
The marketing and promotion of an exotic pet veterinary practice allows the use of strategies that are not necessarily available in other veterinary disciplines. The advantage that an exotics practice enjoys is that it is able to capitalize not only on the unique nature of the species being attended but also on the specialized features of the hospital itself that make it specifically appropriate in caring for exotic pets. Before marketing, however, comes the responsibility that the practice live up to the claims made in promotional materials. A practice cannot ethically be presented as an "exotics" practice if it is nothing more than a dog and cat facility that is willing to attend to exotic pets. It is the competence of the veterinary staff and the appropriateness of the facility that determines the suitability of the practice for exotics management. PMID:16129354
Superdeformed oblate superheavy nuclei
Jachimowicz, P.; Kowal, M.; Skalski, J.
2011-05-15
We study stability of superdeformed oblate (SDO) superheavy Z{>=}120 nuclei predicted by systematic microscopic-macroscopic calculations in 12D deformation space and confirmed by the Hartree-Fock calculations with the SLy6 force. We include into consideration high-K isomers that very likely form at the SDO shape. Although half-lives T{sub 1/2} < or approx. 10{sup -5} s are calculated or estimated for even-even spin-zero systems, decay hindrances known for high-K isomers suggest that some SDO superheavy nuclei may be detectable by the present experimental technique.
NASA Astrophysics Data System (ADS)
Redon, N.; Prévost, A.; Guinet, D.; Lautesse, Ph.; Meyer, M.; Rossé, B.; Stézowski, O.; Nolan, P. J.; Andreoiu, C.; Boston, A. J.; Descovich, M.; Evans, A. O.; Gros, S.; Norman, J.; Page, R. D.; Paul, E. S.; Rainovski, G.; Sampson, J.; de France, G.; Casandjian, J. M.; Theisen, Ch.; Scheurer, J. N.; Nyakó, B. M.; Gál, J.; Kalinka, G.; Molnár, J.; Dombrádi, Zs.; Timár, J.; Zolnai, L.; Juhász, K.; Astier, A.; Deloncle, I.; Porquet, M. G.; Wadsworth, R.; Raddon, P.; Lee, Y.; Wilkinson, A.; Joshi, P.; Simpson, J.; Appelbe, D.; Joss, D.; Lemmon, R.; Smith, J.; Cullen, D.; Brondi, A.; La Rana, G.; Moro, R.; Vardacci, E.; Girod, M.
2004-02-01
The structure of the very neutron-deficient rare-earth nuclei has been investigated in the first experiment with the EXOGAM gamma array coupled to the DIAMANT light charged particle detector using radioactive beam of 76Kr delivered by the SPIRAL facility. Very neutron-deficient Pr, Nd and Pm isotopes have been populated at rather high spin by the reaction 76Kr + 58Ni at a beam energy of 328 MeV. We report here the first results of this experiment.
Redon, N.; Guinet, D.; Lautesse, Ph.; Meyer, M.; Rosse, B.; Stezowski, O.; France, G. de; Casandjian, J. M.
2004-02-27
The structure of the very neutron-deficient rare-earth nuclei has been investigated in the first experiment with the EXOGAM gamma array coupled to the DIAMANT light charged particle detector using radioactive beam of 76Kr delivered by the SPIRAL facility. Very neutron-deficient Pr, Nd and Pm isotopes have been populated at rather high spin by the reaction 76Kr + 58Ni at a beam energy of 328 MeV. We report here the first results of this experiment.
Current Status of Exotic Hadrons
Saeed, M.A.; Ahmed, Maqsood; Fazal-e-Aleem
2005-03-17
Physics of exotic hadrons is in the limelight these days. The models for these baryons are discussed as well as their production and decay processes and methods of their identification. The results of recent experiments in this field are presented, in which some unusual states are observed. These states are candidates for exotic hadrons.
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. PMID:25222372
Exotic States of Nuclear Matter
NASA Astrophysics Data System (ADS)
Lombardo, Umberto; Baldo, Marcello; Burgio, Fiorella; Schulze, Hans-Josef
2008-02-01
pt. A. Theory of nuclear matter EOS and symmetry energy. Constraining the nuclear equation of state from astrophysics and heavy ion reactions / C. Fuchs. In-medium hadronic interactions and the nuclear equation of state / F. Sammarruca. EOS and single-particle properties of isospin-asymmetric nuclear matter within the Brueckner theory / W. Zuo, U. Lombardo & H.-J. Schulze. Thermodynamics of correlated nuclear matter / A. Polls ... [et al.]. The validity of the LOCV formalism and neutron star properties / H. R. Moshfegh ... [et al.]. Ferromagnetic instabilities of neutron matter: microscopic versus phenomenological approaches / I. Vidaã. Sigma meson and nuclear matter saturation / A. B. Santra & U. Lombardo. Ramifications of the nuclear symmetry energy for neutron stars, nuclei and heavy-ion collisions / A. W. Steiner, B.-A. Li & M. Prakash. The symmetry energy in nuclei and nuclear matter / A. E. L. Dieperink. Probing the symmetry energy at supra-saturation densities / M. Di Toro et al. Investigation of low-density symmetry energy via nucleon and fragment observables / H. H. Wolter et al. Instability against cluster formation in nuclear and compact-star matter / C. Ducoin ... [et al.]. Microscopic optical potentials of nucleon-nucleus and nucleus-nucleus scattering / Z.-Y. Ma, J. Rong & Y.-Q. Ma -- pt. B. The neutron star crust: structure, formation and dynamics. Neutron star crust beyond the Wigner-Seitz approximation / N. Chamel. The inner crust of a neutron star within the Wigner-Seitz method with pairing: from drip point to the bottom / E. E. Saperstein, M. Baldo & S. V. Tolokonnikov. Nuclear superfluidity and thermal properties of neutron stars / N. Sandulescu. Collective excitations: from exotic nuclei to the crust of neutron stars / E. Khan, M. Grasso & J. Margueron. Monte Carlo simulation of the nuclear medium: fermi gases, nuclei and the role of Pauli potentials / M. A. Pérez-García. Low-density instabilities in relativistic hadronic models / C. Provid
Heavy quark in exotic hadron and nuclear systems
NASA Astrophysics Data System (ADS)
Yasui, Shigehiro
2014-09-01
In recent years, it has turned out that heavy hadrons with charm and bottom flavors have rich structures, which are different from simple quark-antiquark or three-quark systems. The new states of heavy hadrons are called exotic hadrons X, Y and Z. The subjects are now covering not only exotic hadrons but also exotic ``nuclei'' in which heavy hadrons are bound. The purpose of the presentation is to discuss the general properties of exotic states of hadrons and nuclei with heavy quarks. We begin our discussion by the heavy quark spin (HQS) symmetry in the heavy quark limit, and show that all heavy hadrons are classified by the HQS symmetry, i.e. either HQS singlet or doublet. Next, in order to discuss the long-range physics of exotic hadrons, we introduce the heavy hadron effective theory according to the HQS symmetry in heavy quark sector as well as by chiral symmetry in light quark sector. As examples, we investigate the theoretically possible states of hadronic molecules with an anti-D meson (B meson) and nucleons with baryon number one, two and infinity (i.e. nuclear matter). Calculating the energies, we show that many of them exhibit the HQS doublets. Beyond the leading order in heavy quark limit, we further discuss the 1/M corrections with heavy hadron mass M, and show that finding the HQS-breaking (non-breaking) terms at 1/M is important to investigate the magnetic (electric) gluons in the heavy hadrons in nuclear medium [1,5]. In recent years, it has turned out that heavy hadrons with charm and bottom flavors have rich structures, which are different from simple quark-antiquark or three-quark systems. The new states of heavy hadrons are called exotic hadrons X, Y and Z. The subjects are now covering not only exotic hadrons but also exotic ``nuclei'' in which heavy hadrons are bound. The purpose of the presentation is to discuss the general properties of exotic states of hadrons and nuclei with heavy quarks. We begin our discussion by the heavy quark spin (HQS
Octupole shapes in heavy nuclei
Ahmad, I.
1994-08-01
Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets.
Exotic Bbb R4 and quantum field theory
NASA Astrophysics Data System (ADS)
Asselmeyer-Maluga, Torsten; Mader, Roland
2012-02-01
Recent work on exotic smooth Bbb R4,s, i.e. topological Bbb R4 with exotic differential structure, shows the connection of 4-exotics with the codimension-1 foliations of S3, SU(2) WZW models and twisted K-theory KH(S3), H in H3(S3,Bbb Z). These results made it possible to explicate some physical effects of exotic 4-smoothness. Here we present a relation between exotic smooth Bbb R4 and operator algebras. The correspondence uses the leaf space of the codimension-1 foliation of S3 inducing a von Neumann algebra W(S3) as description. This algebra is a type III1 factor lying at the heart of any observable algebra of QFT. By using the relation to factor II, we showed that the algebra W(S3) can be interpreted as Drinfeld-Turaev deformation quantization of the space of flat SL(2, Bbb C) connections (or holonomies). Thus, we obtain a natural relation to quantum field theory. Finally we discuss the appearance of concrete action functionals for fermions or gauge fields and its connection to quantum-field-theoretical models like the Tree QFT of Rivasseau.
Exotics from Heavy Ion Collisions
Ohnishi, Akira; Jido, Daisuke; Cho, Sungtae; Furumoto, Takenori; Yazaki, Koichi; Hyodo, Tetsuo; Ko, Che Ming; Lee, Su Houng; Nielsen, Marina; Sekihara, Takayasu; Yasui, Shigehiro
2011-10-21
Discriminating hadronic molecular and multi-quark states is a long standing problem in hadronic physics. We propose here to utilize relativistic heavy ion collisions to resolve this problem, as exotic hadron yields are expected to be strongly affected by their structures. Using the coalescence model, we find that the exotic hadron yield relative to the statistical model result is typically an order of magnitude smaller for a compact multi-quark state, and larger by a factor of two or more for a loosely bound hadronic molecule. We further find that some of the newly proposed heavy exotic states could be produced and realistically measured at RHIC and LHC.
Recent Astrophysical Studies with Exotic Beams at ORNL
Bardayan, Daniel W
2006-02-01
The availability of exotic beams has produced great opportunities for advances in our understanding of the nucleosynthesis occurring in stellar burning and stellar explosions such as novae, X-ray bursts, and supernovae. In these extreme environments, synthesized radioactive nuclei can undergo subsequent nuclear processing before they decay, and thus to understand these events, we must understand reaction rates involving radioactive nuclei. At the ORNL Holi led Radioactive Ion Beam Facility (HRIBF), we have made several recent measurements using proton-rich beams such as 18F and 7Be and neutron-rich beams such as 82Ge and 84Se that help clarify the structure of astrophysically-important nuclei. We are also poised to begin studies with doubly-magic 132Sn. The experimental methods and results are discussed.
Recent astrophysical studies with exotic beams at ORNL
NASA Astrophysics Data System (ADS)
Bardayan, D. W.
2006-03-01
The availability of exotic beams has produced great opportunities for advances in our understanding of the nucleosynthesis occurring in stellar burning and stellar explosions such as novae, X-ray bursts, and supernovae. In these extreme environments, synthesized radioactive nuclei can undergo subsequent nuclear processing before they decay, and thus to understand these events, we must understand reaction rates involving radioactive nuclei. At the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), we have made a number of measurements using proton-rich beams such as 18F and 7Be and neutron-rich beams such as 82Ge and 84Se that help clarify the structure of astrophysically-important nuclei. We are also poised to begin studies with doubly-magic 132Sn. The experimental methods and results are discussed.
Material Research Using Moessbauer Spectroscopy With Exotic Nuclei
Kobayashi, Y.
2009-05-04
We have succeeded to obtain in-beam Moessbauer spectra using a short-lived {sup 57}Mn (T{sub 1/2} = 1.45 min) probes implanted into some different types of samples, in order to study the chemical states of the excited atoms produced just after nuclear decays and/or the dynamic behaviors of isolated single atoms in a semiconductor. {sup 57}Mn was produced as a radioactive beam following a nuclear projectile-fragmentation reaction of {sup 58}Fe{sup 21+} beams (E = 63 MeV/nucleon) with Be production target, and separated by the in-flight isotope separator at the accelerators in RIKEN Nishina Center. From the temperature dependence of obtained Moessbauer parameters of the isomer shift (I.S.), the quadrupole splitting (Q.S.), and the linewidth (I), the chemical species and the dynamic behavior of the isolated atoms could be discussed. The in-beam Moessbauer technique combined with a short-lived RI beam is a very powerful tool to investigate the products after nuclear transformations and the dynamics of dilute impurities in solids.
In-flight decay spectroscopy of exotic light nuclei
Charity, R. J.
2012-11-20
In-flight-decay spectroscopy is discussed, including its advantages and disadvantages. In particular the use of in-flight-decay spectroscopy for the study of two-proton decay along isobaric multiplets in highlighted.
Core transitions in the breakup of exotic nuclei
NASA Astrophysics Data System (ADS)
Summers, N. C.; Nunes, F. M.; Thompson, I. J.
2006-03-01
An interesting physical process has been unveiled: Dynamical core excitation during a breakup reaction of loosely bound core+N systems. These reactions are typically used to extract spectroscopic information and/or astrophysical information. A new method, the eXtended Continuum Discretized Coupled Channel (XCDCC) method, was developed to incorporate, in a consistent way and to all orders, core excitation in the bound and scattering states of the projectile, as well as dynamical excitation of the core as it interacts with the target. The model predicts cross sections to specific states of the core. It is applied to the breakup of Be11 on Be9 at 60 MeV/nucleon, and the calculated cross sections are in improved agreement with the data. The distribution of the cross section amongst the various core states is shown to depend on the reaction model used, and not simply on the ground state spectroscopic factors.
Exotic structure in light neutron-rich nuclei
Itagaki, N.; Zhao, P. W.; Meng, J.; Matsuno, H.; Suhara, T.
2015-10-15
In this presentation I discussed two subjects. One is the persistence of threefold symmetry in the ground state of {sup 12}C. Recently D{sub 3h} symmetry has been established in {sup 12}C, which reflects the geometric symmetry of the three α particles. Although the spin-orbit interaction plays a significant role and this interaction breaks the α clusters, we show that threefold symmetry of {sup 12}C is still there. We use AQCM approach and discuss that inclusion of spin-orbit interaction, which is absent in the conventional microscopic α cluster models, is possible keeping the threefold symmetry. The second subject is the appearance of rod shape in C isotopes, which has been investigated in the framework of the cranking covariant density functional theory. The relationship between the stability of such states and the spin and isospin degrees of freedom is discussed; adding valence neutrons and rotating the system. These two effects stabilize the rod shape, and in addition, their coherent effect has been found; the σ-orbits (parallel to the symmetry axis) of the valence neutrons, which enhances the rod shape, is lowered by the rotation of the system, and this σ-orbit pulls down the single particle energies of protons with linear configuration owing to the proton-neutron interaction effect.
New Generation of Physics with Exotic Nuclei at RIBF
Sakurai, H.
2011-10-28
I report present status and perspectives of RIBF 'RI Beam Factory (RIBF)' at RIKEN. RIBF is a top world-class in-flight RIB facility. Emphasis is given to on-going and future programs at the new facility through introducing experimental devices and recent highlights.
EXOTIC MAGNETS FOR ACCELERATORS.
WANDERER, P.
2005-09-18
Over the last few years, several novel magnet designs have been introduced to meet the requirements of new, high performance accelerators and beam lines. For example, the FAIR project at GSI requires superconducting magnets ramped at high rates ({approx} 4 T/s) in order to achieve the design intensity. Magnets for the RIA and FAIR projects and for the next generation of LHC interaction regions will need to withstand high doses of radiation. Helical magnets are required to maintain and control the polarization of high energy protons at RHIC. In other cases, novel magnets have been designed in response to limited budgets and space. For example, it is planned to use combined function superconducting magnets for the 50 GeV proton transport line at J-PARC to satisfy both budget and performance requirements. Novel coil winding methods have been developed for short, large aperture magnets such as those used in the insertion region upgrade at BEPC. This paper will highlight the novel features of these exotic magnets.
NASA Astrophysics Data System (ADS)
Hofmann, Sigurd
2015-11-01
Scientifically based searches for elements beyond uranium started after the discovery of the neutron. Neutrons captured by uranium nuclei and subsequent {β }- decay, similarly as most of the elements were produced in nature, was the successful method applied. However, as a first result, Hahn and Strassmann discovered nuclear fission indicating a limit for the existence of nuclei at an increasing number of protons. Eventually, the nuclear shell model allowed for a more accurate calculation of binding energies, half-lives and decay modes of the heaviest nuclei. Theoreticians predicted a region of increased stability at proton number Z = 126, later shifted to 114, and neutron number N = 184. These nuclei receive their stability from closed shells for the protons and neutrons. Later, increased stability was also predicted for deformed nuclei at Z = 108 and N = 162. In this review I will report on experimental work performed on research to produce and identify these super-heavy nuclei (SHN). Intensive heavy ion beams, sophisticated target technology, efficient electromagnetic ion separators, and sensitive detector arrays were the prerequisites for discovery of 12 new elements during the last 40 years. The results are described and compared with theoretical predictions and interpretations. An outlook is given on further improvement of experimental facilities which will be needed for exploration of the extension and structure of the island of SHN, in particular for searching for isotopes with longer half-lives predicted to be located in the south east of the island, for new elements, and last not least, for surprises which, naturally, emerge unexpectedly.
Halo or skin in the excited states of some light mirror nuclei
NASA Astrophysics Data System (ADS)
Chen, J. G.; Cai, X. Z.; Shen, W. Q.; Ma, Y. G.; Ren, Z. Z.; Zhang, H. Y.; Jiang, W. Z.; Zhong, C.; Wei, Y. B.; Guo, W.; Zhou, X. F.; Wang, K.; Ma, G. L.
2005-01-01
The properties of three pairs of mirror nuclei 13N- 13C, 15N- 15O and 21Na- 21Ne (these mirror nuclei are all made of a good inert core plus an unpaired valence nucleon) are investigated by using the nonlinear relativistic mean-field (RMF) theory. It is found that the calculated binding energies with two different parameter sets are very close to the experimental ones for both the ground states and the excited states except for the large deformed nuclei. The calculations show that the 2 s1/2 excited states of 15N and of 21Na are both weakly bound with a proton halo and a proton skin (or a pigmy proton skin), respectively. In addition, the 1 d5/2 excited state of 13C and the 2 s1/2 excited state of 15O are also weakly bound with a neutron skin, respectively. The ratio of the valence nucleon radius to matter radius is deduced and it can be regarded as an additional criterion for the existence of exotic structure. The unbound 2 s1/2 and 1 d5/2 excited states of 13N are also discussed.
NASA Astrophysics Data System (ADS)
Doornenbal, P.; Scheit, H.; Takeuchi, S.; Aoi, N.; Li, K.; Matsushita, M.; Steppenbeck, D.; Wang, H.; Baba, H.; Ideguchi, E.; Kobayashi, N.; Kondo, Y.; Lee, J.; Michimasa, S.; Motobayashi, T.; Poves, A.; Sakurai, H.; Takechi, M.; Togano, Y.; Yoneda, K.
2016-04-01
The transition strengths of the first-excited 2+ states and deformation lengths of the nuclei 30Ne and 36Mg were determined via Coulomb- and nuclear-force-dominated inelastic scattering at intermediate energies. Beams of these exotic nuclei were produced at the RIKEN Radioactive Isotope Beam Factory and were incident on lead and carbon targets at energies above 200 MeV/u . Absolute excitation cross sections on the lead target yielded reduced transition probabilities of 0.0277(79) and 0.0528(121) e2b2 , while the measurements with the carbon target revealed nuclear deformation lengths of δN=1.98 (11) and 1.93(11) fm for 30Ne and 36Mg, respectively. Corresponding quadrupole deformation parameters of β2˜0.5 from the two probes were found comparable in magnitude, showing no indication for a reduction in deformation along isotopic and isotonic chains from 32Mg towards the neutron drip-line. Comparisons to shell-model calculations illustrate the importance of neutron excitations across the N =20 shell for 30Ne and suggest that shallow maximums of collectivity may occur around N =22 and 24 along the neon and magnesium isotopic chains, respectively.
Structure of neutron-rich nuclei
Nazarewicz, W. ||
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.
Multiple muons of conventional and exotic origin in DUMAND
NASA Technical Reports Server (NTRS)
Grieder, K. F.
1985-01-01
A first summary of results from a theoretical analysis, based on hadron - muon cascade calculations, that yield relative intensities of very high energy multiple muons originating from ultra high energy interactions initiated by primary protons and iron nuclei in the atmosphere, under consideration of normal as well as direct and exotic production channels is presented. Lateral density distributions and target diagrams will be presented which show that only very large detectors, such as DUMAND, will be able to record multiple muons of conventional origin reliably. This, however, is a prerequisite for any primary mass determination based on multiple muon data.
Mirror nuclei constraint in nuclear mass formula
Wang Ning; Liang Zuoying; Liu Min; Wu, Xizhen
2010-10-15
The macroscopic-microscopic mass formula is further improved by considering mirror nuclei constraint. The rms deviation with respect to 2149 measured nuclear masses is reduced to 0.441 MeV. The shell corrections, the deformations of nuclei, the neutron and proton drip lines, and the shell gaps are also investigated to test the model. The rms deviation of {alpha}-decay energies of 46 superheavy nuclei is reduced to 0.263 MeV. The predicted central position of the superheavy island could lie around N=176{approx}178 and Z=116{approx}120 according to the shell corrections of nuclei.
LOUISIANA EXOTIC INVASIVE SPECIES SYMPOSIUM MX964256
The Louisiana Exotic Invasive Species Symposium will provide a multi-state collaboration among agency representatives, scientists, and the affected public to address the problem of exotic invasive species and to improve coastal environmental conditions in Louisiana.
Exotic aphid control with pathogens
Technology Transfer Automated Retrieval System (TEKTRAN)
Exotic aphids are invading ecosystems worldwide. The principal factors favoring establishment of these pests are their small size, parthenogenetic reproduction, short generation time, ability for long distance dispersal as winged morphs, and explosive population dynamics. In the past, attention to i...
Exotic smoothness and quantum gravity
NASA Astrophysics Data System (ADS)
Asselmeyer-Maluga, T.
2010-08-01
Since the first work on exotic smoothness in physics, it was folklore to assume a direct influence of exotic smoothness to quantum gravity. Thus, the negative result of Duston (2009 arXiv:0911.4068) was a surprise. A closer look into the semi-classical approach uncovered the implicit assumption of a close connection between geometry and smoothness structure. But both structures, geometry and smoothness, are independent of each other. In this paper we calculate the 'smoothness structure' part of the path integral in quantum gravity assuming that the 'sum over geometries' is already given. For that purpose we use the knot surgery of Fintushel and Stern applied to the class E(n) of elliptic surfaces. We mainly focus our attention to the K3 surfaces E(2). Then we assume that every exotic smoothness structure of the K3 surface can be generated by knot or link surgery in the manner of Fintushel and Stern. The results are applied to the calculation of expectation values. Here we discuss the two observables, volume and Wilson loop, for the construction of an exotic 4-manifold using the knot 52 and the Whitehead link Wh. By using Mostow rigidity, we obtain a topological contribution to the expectation value of the volume. Furthermore, we obtain a justification of area quantization.
Exotic power and propulsion concepts
NASA Technical Reports Server (NTRS)
Forward, Robert L.
1990-01-01
The status of some exotic physical phenomena and unconventional spacecraft concepts that might produce breakthroughs in power and propulsion in the 21st Century are reviewed. The subjects covered include: electric, nuclear fission, nuclear fusion, antimatter, high energy density materials, metallic hydrogen, laser thermal, solar thermal, solar sail, magnetic sail, and tether propulsion.
SEARCHING FOR EXOTIC SPODOPTERA SPECIES
Technology Transfer Automated Retrieval System (TEKTRAN)
We used sex pheromone-baited traps to collect native and exotic Spodoptera spp. moths at an orchid nursery in Lake County, FL. Lures for S. eridania, exempta, exigua, frugiperda, littoralis, litura, praefica, and Pseudaletia unipuncta were placed in bucket traps that surrounded the greenhouses of t...
NASA Technical Reports Server (NTRS)
Raisbeck, G. M.
1986-01-01
Cosmogenic nuclei, nuclides formed by nuclear interactions of galactic and solar cosmic rays with extraterrestrial or terrestrial matter are discussed. Long lived radioactive cosmogenic isotopes are focused upon. Their uses in dating, as tracers of the interactions of cosmic rays with matter, and in obtaining information on the variation of primary cosmic ray flux in the past are discussed.
Strong, weak and electromagnetic forces at work in atomic nuclei, decay properties
NASA Astrophysics Data System (ADS)
Benzoni, G.
2016-04-01
A survey of basic properties of the decay of unstable nuclei is here presented, with a focus on α and β decay. An overview of basic properties and the description of few examples of recently measured decays in exotic nuclei are given in the lecture.
Study of Weakly Bound Nuclei at RIKEN RIBF
NASA Astrophysics Data System (ADS)
Motobayashi, Tohru
2016-05-01
Recent highlights of studies on unbound exotic nuclei at the RIKEN RI beam factory (RIBF) are presented. They include spectroscopy of nuetron-rich oxygen isotopes ^{26}O and ^{28}O, search for four-neutron states, and studies of proton unbound states of astrophysical interest.
Code of Federal Regulations, 2011 CFR
2011-01-01
... CERTIFICATION EXOTIC ANIMALS AND HORSES; VOLUNTARY INSPECTION Exotic Animals § 352.13 Handling and disposal of condemned or other inedible exotic animal products at official exotic animal establishments. This shall be... other inedible exotic animal products at official exotic animal establishments. 352.13......
Code of Federal Regulations, 2010 CFR
2010-01-01
... CERTIFICATION EXOTIC ANIMALS AND HORSES; VOLUNTARY INSPECTION Exotic Animals § 352.13 Handling and disposal of condemned or other inedible exotic animal products at official exotic animal establishments. This shall be... other inedible exotic animal products at official exotic animal establishments. 352.13......
Spatial dependence of pairing in deformed nuclei
Balbutsev, E. B.; Malov, L. A.; Schuck, P.
2011-11-15
The solution of time-dependent Hartree-Fock-Bogoliubov equations by the Wignerfunction-moments method leads to the appearance of refined low-lying modes whose description requires the accurate knowledge of the anomalous density matrix. It is shown that calculations with Woods-Saxon potential satisfy this requirement, producing an anomalous density matrix of the same quality as more complicated calculations with realistic forces.
Onset of deformation in polonium nuclei
Younes, W.; Cizewski, J.A.
1996-12-31
The authors have been able to reproduce the systematics of the positive-parity states in {sup 192-208}Po within the framework of the Particle-Core Model. The wave-functions of the 2{sup +}{sub 1} states have been extracted using the Quasiparticle Random Phase Approximation. The increase in the collective motion of the lighter isotopes comes from the increased proton-neutron interaction when the neutrons and protons both occupy high-j orbitals.
Study of 0+ States in Deformed Nuclei
Lesher, S. R.; Ammar, Z.; Merrick, M.; Hannant, C. D.; Boukharouba, N.; McEllistrem, M. T.; Yates, S. W.; Warr, N.; Fransen, C.; Brown, T. B.
2006-03-13
In recent 160Gd(p,t) reaction studies the existence of more than ten 0+ states in 158Gd below 3.0 MeV was revealed. We have examined 158Gd with the (n,n'{gamma}) reaction at neutron energies up to 3.5 MeV to confirm the identification of these states and to determine their lifetimes through DSAM measurements. Gamma-ray excitation function and angular distribution measurements have been performed and {gamma} - {gamma} coincidences have been measured with the KEGS array of detectors. Moderately strong decays are observed from some of these 0+ states.
Spin Modes in Nuclei and Nuclear Forces
Suzuki, Toshio; Otsuka, Takaharu
2011-05-06
Spin modes in stable and unstable exotic nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain shell evolutions toward drip-lines and spin properties of both stable and exotic nuclei, for example, Gamow-Teller transitions in {sup 12}C and {sup 14}C and an anomalous M1 transition in {sup 17}C. The importance and the necessity of the repulsive monopole corrections in isospin T = 1 channel to the microscopic two-body interactions are pointed out. The corrections are shown to lead to the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by {Delta} excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies and transitions in exotic oxygen and calcium isotopes are demonstrated.
Spin Modes in Nuclei and Nuclear Forces
NASA Astrophysics Data System (ADS)
Suzuki, Toshio; Otsuka, Takaharu
2011-05-01
Spin modes in stable and unstable exotic nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain shell evolutions toward drip-lines and spin properties of both stable and exotic nuclei, for example, Gamow-Teller transitions in 12C and 14C and an anomalous M1 transition in 17C. The importance and the necessity of the repulsive monopole corrections in isospin T = 1 channel to the microscopic two-body interactions are pointed out. The corrections are shown to lead to the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by Δ excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies and transitions in exotic oxygen and calcium isotopes are demonstrated.
Properties of the hypothetical spherical superheavy nuclei
Smolanczuk, R. |
1997-08-01
Theoretical results on the ground-state properties of the hypothetical spherical superheavy atomic nuclei are presented and discussed. Even-even isotopes of elements Z=104{minus}120 are considered. Certain conclusions are also drawn for odd-A and odd-odd superheavy nuclei. Results obtained earlier for even-even deformed superheavy nuclei with Z=104{minus}114 are given for completeness. Equilibrium deformation, nuclear mass, {alpha}-decay energy, {alpha}-decay half-life, dynamical fission barrier, as well as spontaneous-fission half-life are considered. {beta}-stability of superheavy nuclei is also discussed. The calculations are based on the macroscopic-microscopic model. A multidimensional deformation space describing axially symmetric nuclear shapes is used in the analysis of masses and decay properties of superheavy nuclei. We determined the boundaries of the region of superheavy nuclei which are expected to live long enough to be detected after the synthesis in a present-day experimental setup. {copyright} {ital 1997} {ital The American Physical Society}
Exotic containers for capillary surfaces
NASA Technical Reports Server (NTRS)
Concus, Paul; Finn, Robert
1991-01-01
This paper discusses 'exotic' rotationally symmetric containers that admit an entire continuum of distinct equilibrium capillary free surfaces. The paper extends earlier work to a larger class of parameters and clarifies and simplifies the governing differential equations, while expressing them in a parametric form appropriate for numerical integration. A unified presentation suitable for both zero and nonzero gravity is given. Solutions for the container shapes are depicted graphically along with members of the free-surface continuum, and comments are given concerning possible physical experiments.
NASA Astrophysics Data System (ADS)
Shan, Wei
2016-05-01
The BESIII Experiment at the Beijing Electron Positron Collider (BEPC2) collected large data samples for electron-positron collisions with center-of-mass above 4 GeV during 2013 and 2014. In this mass region, there are several states that are yet to be understood. In this article we will discuss BESIII analyses of the exotic Zc states. We present the studies of their decays to hidden charm and open charm final states for both the charged and neutral Zc states.
From hadrons to nuclei with charm and bottom flavors
Yasui, S.; Sudoh, K.
2011-10-21
We discuss new exotic nuclei which contain D-bar and B mesons. As simplest systems, we consider D-bar(B) bound systems with one nucleon and two nucleons. With respecting to the heavy quark symmetry, we derive the one pion exchange potential as a long range force as an interaction between D-bar(B) meson and nucleon. We solve the Schroedinger equation with coupled channels, and investigate the D-barN (BN) bound states. We further discuss the possibility of existence of D-barNN (BNN). We discuss the possible observations of these exotic states in experiments in accelerator facilities.
Photoproduction of exotic baryon resonances
NASA Astrophysics Data System (ADS)
Karliner, Marek; Rosner, Jonathan L.
2016-01-01
We point out that the new exotic resonances recently reported by LHCb in the J / ψ p channel are excellent candidates for photoproduction off a proton target. This test is crucial to confirming the resonant nature of such states, as opposed to their being kinematical effects. We specialize to an interpretation of the heavier narrow state as a molecule composed of Σc and Dbar*, and estimate its production cross section using vector dominance. The relevant photon energies and fluxes are well within the capabilities of the GlueX and CLAS12 detectors at Thomas Jefferson National Accelerator Facility (JLAB). A corresponding calculation is also performed for photoproduction of an analogous resonance which is predicted to exist in the ϒp channel.
Potential Habitats for Exotic Life Within the Life Supporting Zone
NASA Astrophysics Data System (ADS)
Leitner, Johannes J.; Firneis, Maria G.; Hitzenberger, Regina
2010-05-01
System and beyond have been compiled. Dynamical investigations (related to the interior of superearths), but also heat transport regimes and potential cycles with exotic solvents as well as tidal heating processes and their influence on the thermal regime of the planets will help to define the regions of potential exotic life more precisely. Atmospheric and subsurface cycles which can take place in such habitats as well as cloud and droplet formation with and without cloud nuclei cores will further extend our knowledge on mechanisms relevant for the stability of these systems. Finally the question of suitable biomarkers, which can enable the observation of exotic habitats and their potential life forms will be considered in the research platform. In this context a special topic is also the bandwidth of photosynthesis: how is the influence of different atmospheric gases and what are the environment conditions for the chemical reactions of photosynthesis? First preliminary results for the life supporting zones of selected planetary systems will be presented. References: [1] NRC (National Research Council)(2007) The Limits of Organic Life in Planetary Systems, National Academies Press, Washington, DC 20001, ISBN 978-0-309-10484-5. [2] Kasting, J.F., Whitmore D.P. and Reynolds R.T. (1993) Icarus, 101, 109-128.
Selfconsistent calculations for hyperdeformed nuclei
Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D.
1996-12-31
Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.
Transitional nuclei near shell closures
Mukherjee, G.
2014-08-14
High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.
Exploration of High-Dimensional Nuclei Data
Fuentes, Fernando; Kettani, Houssain; Ostrouchov, George; Stoitsov, Mario; Nam, Hai Ah
2010-01-01
Density Functional Theory (DFT) provides the theoretical foundation for a self-consistent mean-field description of the nucleus in terms of one-body densities and currents. The idea is to construct a functional whose input is the proton and neutron densities and currents, and whose output yields the ground-state energy and other properties of the nucleus. Extensive computations of ground-state energies and other observable properties of several thousand nuclei are required in order to find a universal functional that covers the entire chart of nuclei. The analysis looks for hidden relationships between observables to determine a functional that can reliably predict nuclear properties in regions where no experimental data exist. Using methods for dimension reduction and visualization tools, it is hypothesized that the deformation of the neutrons is related to other characteristics of the nuclei. The discovered relationships with the deformation of the neutrons take us a step closer toward the universal functional.
Radiative neutron captures by neutron-rich nuclei and the r-process nucleosynthesis
NASA Astrophysics Data System (ADS)
Goriely, S.
1998-09-01
The radiative neutron capture by neutron-rich nuclei is estimated with an improved description of the electric giant dipole resonance. In addition, 3 major effects affecting the capture rates by exotic neutron-rich nuclei are studied. These concern the existence of a low-energy E1 pygmy resonance, the overestimate of the statistical predictions for resonance-deficient nuclei and the direct capture mechanism. The total (n,γ) reaction rates including these 3 effects are evaluated for 3100 neutron-rich nuclei and used in parametric r-process calculations to analyze their impact on the r-abundance distribution.
Collective properties of drip-line nuclei
Hamamoto, I.; Sagawa, H.
1996-12-31
Performing the spherical Hartree-Fock (HF) calculations with Skyrme interactions and, then, using RPA solved in the coordinate space with the Green`s function method, the authors have studied the effect of the unique shell structure as well as the very low particle threshold on collective modes in drip line nuclei. In this method a proper strength function in the continuum is obtained, though the spreading width of collective modes is not included. They have examined also one-particle resonant states in the obtained HF potential. Unperturbed particle-hole (p-h) response functions are carefully studied, which contain all basic information on the exotic behaviour of the RPA strength function in drip line nuclei.
Central Appalachian Exotic Terranes and Exposures of Former Orogenic Middle Crust
NASA Astrophysics Data System (ADS)
Martin, A. J.
2015-12-01
In the northern and southern Appalachians, rocks that formed Paleozoic orogenic middle crust mostly are exposed within or directly inboard of terranes that originated near Gondwana. Most outcrops of the Paleozoic orogenic middle crust of the eastern edge of Laurentia occur adjacent to these exotic terranes. However, a narrow belt of Paleozoic orogenic middle crust is exposed in the Piedmont of the central Appalachians despite the absence of recognized exotic terranes. The presence of these deformed, amphibolite facies rocks raises the questions: "Did central Appalachian orogeny occur in the absence of accreted exotic terranes?" and, more generally, "Is exotic terrane collision required for exhumation of Appalachian former middle crust?" Previous U/Pb isotopic dating of spots in detrital zircon revealed the presence of Gondwanan terranes in three locations in the central Appalachians: central Virginia, central Maryland, and southeastern Pennsylvania. Two new samples collected near the discovery locations in Virginia and Maryland yielded prominent peaks in zircon U/Pb age distributions at ca. 630-610 Ma, confirming the Gondwanan affinity of these rocks. Hf isotopic compositions of spots in these upper Neoproterozoic zircon grains range to both more and less depleted than spots in zircon from the few possible Laurentian granitic sources, consistent with derivation of the zircon from Gondwana. Abundant 1700-1000 Ma detrital zircon rules out the West Africa Craton as a potential source; Amazonia is the most likely ultimate source of the zircon. The extent of the exotic terrane(s) in the central Appalachian Piedmont remains enigmatic due to uncertain connections between isolated exposures of the terrane(s). Nevertheless, the discovery of one or more exotic terranes in the central Appalachian Piedmont underscores the relationship between exotic terranes and exposed former middle crust in the Appalachians. This relationship may be a feature of several other major
Traversable wormhole in the deformed Horava-Lifshitz gravity
Son, Edwin J.; Kim, Wontae
2011-06-15
Asymptotically flat wormhole solutions are found in the deformed Horava-Lifshitz gravity. It turns out that higher curvature terms cannot play the role of exotic matters which are crucial to form a traversable wormhole, and external exotic sources are still needed. In particular, the exotic matter behaves like phantom energy if the Kehagias-Sfetsos vacuum is considered outside the wormhole. Interestingly, the spherically symmetric setting makes the matter and the higher curvature contribution satisfy four-dimensional conservation of energy in the covariant form.
Hamiltonian dynamics of an exotic action for gravity in three dimensions
Escalante, Alberto Manuel-Cabrera, J.
2014-04-15
The Hamiltonian dynamics and the canonical covariant formalism for an exotic action in three dimensions are performed. By working with the complete phase space, we report a complete Hamiltonian description of the theory such as the extended action, the extended Hamiltonian, the algebra among the constraints, the Dirac’s brackets and the correct gauge transformations. In addition, we show that in spite of exotic action and tetrad gravity with a cosmological constant give rise to the same equations of motion, they are not equivalent, in fact, we show that their corresponding Dirac’s brackets are quite different. Finally, we construct a gauge invariant symplectic form which in turn represents a complete Hamiltonian description of the covariant phase space. -- Highlights: •We report a detailed Hamiltonian analysis for an exotic action of gravity. •We show that Palatini and exotic actions are not equivalent. •The exotic action is a non-commutative theory. •The fundamental gauge transformations of the theory are Λ-deformed Poincaré transformations. •A Lorentz and gauge invariant symplectic two-form is constructed.
Exotic mammals disperse exotic fungi that promote invasion by exotic trees.
Nuñez, Martin A; Hayward, Jeremy; Horton, Thomas R; Amico, Guillermo C; Dimarco, Romina D; Barrios-Garcia, M Noelia; Simberloff, Daniel
2013-01-01
Biological invasions are often complex phenomena because many factors influence their outcome. One key aspect is how non-natives interact with the local biota. Interaction with local species may be especially important for exotic species that require an obligatory mutualist, such as Pinaceae species that need ectomycorrhizal (EM) fungi. EM fungi and seeds of Pinaceae disperse independently, so they may use different vectors. We studied the role of exotic mammals as dispersal agents of EM fungi on Isla Victoria, Argentina, where many Pinaceae species have been introduced. Only a few of these tree species have become invasive, and they are found in high densities only near plantations, partly because these Pinaceae trees lack proper EM fungi when their seeds land far from plantations. Native mammals (a dwarf deer and rodents) are rare around plantations and do not appear to play a role in these invasions. With greenhouse experiments using animal feces as inoculum, plus observational and molecular studies, we found that wild boar and deer, both non-native, are dispersing EM fungi. Approximately 30% of the Pinaceae seedlings growing with feces of wild boar and 15% of the seedlings growing with deer feces were colonized by non-native EM fungi. Seedlings growing in control pots were not colonized by EM fungi. We found a low diversity of fungi colonizing the seedlings, with the hypogeous Rhizopogon as the most abundant genus. Wild boar, a recent introduction to the island, appear to be the main animal dispersing the fungi and may be playing a key role in facilitating the invasion of pine trees and even triggering their spread. These results show that interactions among non-natives help explain pine invasions in our study area. PMID:23826154
Exotic Mammals Disperse Exotic Fungi That Promote Invasion by Exotic Trees
Nuñez, Martin A.; Hayward, Jeremy; Horton, Thomas R.; Amico, Guillermo C.; Dimarco, Romina D.; Barrios-Garcia, M. Noelia; Simberloff, Daniel
2013-01-01
Biological invasions are often complex phenomena because many factors influence their outcome. One key aspect is how non-natives interact with the local biota. Interaction with local species may be especially important for exotic species that require an obligatory mutualist, such as Pinaceae species that need ectomycorrhizal (EM) fungi. EM fungi and seeds of Pinaceae disperse independently, so they may use different vectors. We studied the role of exotic mammals as dispersal agents of EM fungi on Isla Victoria, Argentina, where many Pinaceae species have been introduced. Only a few of these tree species have become invasive, and they are found in high densities only near plantations, partly because these Pinaceae trees lack proper EM fungi when their seeds land far from plantations. Native mammals (a dwarf deer and rodents) are rare around plantations and do not appear to play a role in these invasions. With greenhouse experiments using animal feces as inoculum, plus observational and molecular studies, we found that wild boar and deer, both non-native, are dispersing EM fungi. Approximately 30% of the Pinaceae seedlings growing with feces of wild boar and 15% of the seedlings growing with deer feces were colonized by non-native EM fungi. Seedlings growing in control pots were not colonized by EM fungi. We found a low diversity of fungi colonizing the seedlings, with the hypogeous Rhizopogon as the most abundant genus. Wild boar, a recent introduction to the island, appear to be the main animal dispersing the fungi and may be playing a key role in facilitating the invasion of pine trees and even triggering their spread. These results show that interactions among non-natives help explain pine invasions in our study area. PMID:23826154
NASA Astrophysics Data System (ADS)
Regan, P. H.
2015-11-01
Precision measurements of electromagnetic transition rates provide accurate inputs into nuclear data evaluations and are also used to test and validate predictions of state of the art nuclear structure models. Measurements of transition rates can be used to ascertain or rule out multipolarity assignments for the measured EM decay, thereby providing spin- and parity-difference information for states between which the EM transition takes place. This conference paper reports on a measurements of electromagnetic transition rates between excited nuclear states using coincidence `fast-timing' gamma-ray spectroscopy with cerium-doped, lanthanum-tribromide (LaBr3(Ce)) detectors. Examples of recent precision measurements using a combined LaBr3-HpGe array based at the tandem accelerator, Bucharest, Romania include studies around the N=20 and N=82 shell closures using stable-beam induced fusion-evaporation reactions; and the evolution of nuclear deformation around in neutron-rich Hf, W and Os nuclei using 7Li-induced light-ion transfer reactions. This paper also presents the ongoing development of a new multidetector LaBr3(Ce) array for future studies of exotic nuclei produced at the upcoming Facility for Anti-Proton and Ion Research (FAIR) as part of the NUSTAR-DESPEC project, and reports on the pre-NUSTAR implementations of detectors from this array to study electromagnetic transition rates in neutron-rich fission fragments at ILL-Grenoble, France and RIBF at RIKEN, Japan.
Understanding nuclei in the upper sd - shell
Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S.
2014-08-14
Nuclei in the upper-sd shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A ≃ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.
Superdeformation in the mercury nuclei
Janssens, R.V.F.; Carpenter, M.P.; Fernandez, P.B.; Moore, E.F.; Ahmad, I.; Khoo, T.L.; Wolfs, F.L.H. ); Drigert, M.W. ); Ye, D.; Beard, K.B.; Garg, U.; Reviol, W. ); Bearden, I.G.; Benet, P.; Daly, P.J.; Grabowski, Z.W. )
1990-01-01
We shall first summarize the present experimental situation concerning {sup 192}Hg, the nucleus regarded as the analog of {sup 152}Dy for this superdeformation (SD) region in that gaps are calculated to occur at large deformation for Z = 80 and N = 112. Proton and neutron excitations out of the {sup 192}Hg core will then be reviewed with particular emphasis on {sup 191}Hg and {sup 193}Tl. The presentation will conclude with a brief discussion on limits of the SD region for neutron deficient Hg nuclei. 26 refs., 10 figs.
Shell And Halo Structure In Neutron-Rich Light Nuclei
Nociforo, C.
2010-06-01
Spectroscopic investigations performed at the neutron drip line in case of sd shell nuclei have recently shown the existence of the new magic numbers Z = 8 and N = 14,16. Predictions within the nuclear shell model calculations for the {sup 23,24}O ground state have been confirmed measuring their neutron occupancy in breakup reactions performed by using the inflight radioactive ion beams produced at the Fragment Separator FRS of GSI. Some perspectives of studying the evolution of magic numbers in this region of light exotic nuclei are given.
New Neutron Rich Nuclei Near {sup 208}Pb
Aeystoe, J.; Andreyev, A.; Evensen, A.-H.; Hoff, P.; Huhta, M.; Huyse, M.; ISOLDE Collaboration; Jokinen, A.; Karny, M.; Kugler, E.; Kurpeta, J.; Lettry, J.; Nieminen, A.; Plochocki, A.; Ramdhane, M.; Ravn, H.; Rykaczewski, K.; Szerypo, J.; VanDuppen, P.; Walter, G.; Woehr, A.
1998-11-13
The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may try to observe and understand the evolution of the nuclear structure while departing in the experiment as far as possible from the stable nuclei. An extension of experimental nuclear structure studies towards the nuclei characterized by high neutron excess is crucial for such verifications as well as for the {tau}-process nucleosynthesis scenario. Heavy neutron-rich nuclei, south-east of doubly-magic {sup 208}Pb, were always very difficult to produce and investigate. The nuclei like {sup 218}Po and {sup 214}Pb or {sup 210}Tl marked the border line of known nuclei from the beginning of the radioactivity era for over ninety years. To illustrate the difficulties, one can refer to the experiments employing the on-line mass separator technique. A spallation of heavy targets like {sup 232}Th and {sup 238}U by high-energy protons was proven as a source of heavy neutron-rich nuclei. The isotopes near and beyond doubly-magic {sup 208}Pb were produced too. However, such studies often suffered from an isobaric contamination of much more strongly produced and efficiently released elements like francium or radon and their decay products. A new experimental technique, based on the pulsed release element selective method recently developed at the PS Booster-ISOLDE at CERN [7,8,9] greatly reduces the contamination of these very short-lived {alpha}-emitters (Z {ge} 84) for the isobaric mass chains A=215 to A=218.
Exotic brane junctions from F-theory
NASA Astrophysics Data System (ADS)
Kimura, Tetsuji
2016-05-01
Applying string dualities to F-theory, we obtain various [ p, q]-branes whose constituents are standard branes of codimension two and exotic branes. We construct junctions of the exotic five-branes and their Hanany-Witten transitions associated with those in F-theory. In this procedure, we understand the monodromy of the single 5 2 2 -brane. We also find the objects which are sensitive to the branch cut of the 5 2 2 -brane. Considering the web of branes in the presence of multiple exotic five-branes analogous to the web of five-branes with multiple seven-branes, we obtain novel brane constructions for SU(2) gauge theories with n flavors and their superconformal limit with enhanced E n+1 symmetry in five, four, and three dimensions. Hence, adapting the techniques of the seven-branes to the exotic branes, we will be able to construct F-theories in diverse dimensions.
Clusters and Halos in Light Nuclei
NASA Astrophysics Data System (ADS)
Neff, Thomas; Feldmeier, Hans
2009-08-01
The structure of light nuclei in the p- and sd-shell features exotic phenomena like halos and clustering. In the Fermionic Molecular Dynamics (FMD) approach we aim at a consistent microscopic description of well bound nuclei and of loosely bound exotic systems. This is possible due to the flexibility of the single-particle basis states using Gaussian wave-packets localized in phase space. Many-body basis states are Slater determinants projected on parity, angular and total linear momentum. The structure of 12C is discussed. Here the ground state band can be well described within a shell model picture but excited states above the three-α threshold, including the famous Hoyle state, show a pronounced cluster structure. As another example we study the structure of the Neon isotopes 17-22Ne. In 17Ne we find a large s2 occupation related to a large charge radius. The charge radius decreases for 18Ne but gets again very large for 19Ne and 20Ne which is explained by significant admixtures of 3He and 4He cluster components into to the ground state wave functions.
Mathematical models for exotic wakes
NASA Astrophysics Data System (ADS)
Basu, Saikat; Stremler, Mark
2014-11-01
Vortex wakes are a common occurrence in the environment around us; the most famous example being the von Kármán vortex street with two vortices being shed by the bluff body in each cycle. However, frequently there can be many other more exotic wake configurations with different vortex arrangements, based on the flow parameters and the bluff body dimensions and/or its oscillation characteristics. Some examples include wakes with periodic shedding of three vortices (`P+S' mode) and four vortices (symmetric `2P' mode, staggered `2P' mode, `2C' mode). We present mathematical models for such wakes assuming two-dimensional potential flows with embedded point vortices. The spatial alignment of the vortices is inspired by the experimentally observed wakes. The idealized system follows a Hamiltonian formalism. Model-based analysis reveals a rich dynamics pertaining to the relative vortex motion in the mid-wake region. Downstream evolution of the vortices, as predicted from the model results, also show good correspondence with wake-shedding experiments performed on flowing soap films.
Exotic terranes of western California
McWilliams, M.O.; Howell, D.G.
1982-01-01
Numerous distinct geological terranes compose the North American Cordillera1; there may be as many as 50 terranes in California alone2. Critical to deciphering the history of Cordilleran tectonic assembly is an understanding of the displacement history of individual terranes. It is therefore important to know: (1) whether a terrane has undergone significant motion with respect to the stable craton (that is, whether it is allochthonous or exotic); (2) if so, when relative motion started and stopped; (3) from where an individual terrane originated; and (4) the nature of interterrane movements. We consider here the problem of determining whether the now-juxtaposed Salinian and Stanley Mountain terranes of California became amalgamated at or near their present position with respect to cratonic North America, or if they collided at a considerable distance from their present positions and were later accreted to North America as a composite package. The palaeomagnetic data that we present indicate that the latter was the case. ?? 1982 Nature Publishing Group.
Compact high resolution isobar separator for study of exotic decays
NASA Astrophysics Data System (ADS)
Shchepunov, V.; Piechaczek, A.; Carter, H. K.; Batchelder, J. C.; Zganjar, E. F.
2009-05-01
A compact isobar separator, based on the Multi-Pass-Time-of-Flight (MTOF) principle, is developed. A mass resolving power (MRP) of 110,000 (FWHM) is achieved as spectrometer with a transmission of 50 - 80%. The transverse beam acceptance and the energy acceptance are 42 π mm mrad and about ± 2.5%. Operated as a separator, molecules of N2 and CO with δM/M = 1/2500 or 10.433 MeV were separated with a Bradbury Nielsen gate. In that mode of operation, the MRP (FWHM) is about 40,000 after 120 laps. To inject radioactive ion beams into the separator, and to further improve its MRP, cooler and buncher RF quadrupoles were designed^1 and tested. A bunch width of 30 ns at 1% of the peak height (FWHM = 9 ns) and a transmission in DC mode of 75 -- 80 % were achieved. With such bunch parameters, MRPs of ˜ 400,000 (FWHM) are expected for the MTOF separator. At HRIBF, it will provide pure samples of exotic nuclides around ^100Sn, of neutron deficient rare-earth nuclei and of neutron-rich nuclei. Incidental measurements of mass differences will determine Qβ values with accuracies of ˜ 1%. ^1 V. Shchepunov and V. Kozlovskiy et al., to be published
Volume integral theorem for exotic matter
Nandi, Kamal Kanti; Zhang Yuanzhong; Kumar, K.B. Vijaya
2004-12-15
We answer an important question in general relativity about the volume integral theorem for exotic matter by suggesting an exact integral quantifier for matter violating Averaged Null Energy Condition (ANEC). It is checked against some well-known static, spherically symmetric traversable wormhole solutions of general relativity with a sign reversed kinetic term minimally coupled scalar field. The improved quantifier is consistent with the principle that traversable wormholes can be supported by arbitrarily small quantities of exotic matter.
Video Otoscopy in Exotic Companion Mammals.
Jekl, Vladimir; Hauptman, Karel; Knotek, Zdenek
2015-09-01
Ear disease is a common disorder seen in exotic companion mammals, especially in ferrets, rabbits, and rats. This article describes patient preparation, equipment, and video otoscopy technique in exotic companion mammals. This noninvasive technique facilitates accurate diagnosis of diseases affecting the external ear canal or middle ear. Moreover, therapeutic otoscopic evaluation of the external ear facilitates foreign body removal, external ear canal flushing, intralesional drug administration, myringotomy, and middle ear cavity flushing. PMID:26117517
Exotic species, Experienced, and Idealized Nature
NASA Astrophysics Data System (ADS)
Prévot-Julliard, Anne-Caroline; Clavel, Joanne; Teillac-Deschamps, Pauline; Julliard, Romain
2011-11-01
This paper is an answer to the Caplat and Coutts forum about our previous paper "The need for flexibility in conservation practices: exotic species as an example". We precise here why we proposed to consider exotic species as well as indigenous species in the reconnection framework in human-modified environments. One argument is that consistent and understandable arguments must be used in the communication from scientists to the public, in order not to decrease the gap between science and society.
Exotic Meson Results from BNL E852
NASA Astrophysics Data System (ADS)
Manak, Joseph J.
1998-10-01
Results from BNL experiment 852 on exotic (non-q\\overlineq) meson production are presented. Production of final states with J^PC = 1^-+ is observed in π^-p interactions at 18 GeV/c in the ηπ^-, ρπ^- and η^'π^- channels. Since such states are manifestly exotic if they are resonant, we describe amplitude analyses which use the interference between these states and other well known states to measure the phase behavior of the J^PC = 1^-+ amplitudes. The analyses show that, in addition to the previously reported(D.R. Thompson et al.), Phys. Rev. Lett. 79, 1630 (1997) evidence for an exotic meson in the ηπ^- channel, there is strong evidence for a second exotic meson decaying to ρπ^- with a mass of M=1593 ±8^+29_-47 MeV/c^2 and a width of Γ=168 ±20^+150_-12 MeV/c^2. We also show that the η^'π^- system is dominated by J^PC = 1^-+ production and we use those data to determine decay branching ratios for the exotic mesons. Such measurements are expected to be crucial in determining the constituent nature of the exotic mesons - that is, whether they are consistent with being hybrid mesons or four-quark states.
Shape coexistence and triaxiality in nuclei near 80Zr
NASA Astrophysics Data System (ADS)
Zheng, S. J.; Xu, F. R.; Shen, S. F.; Liu, H. L.; Wyss, R.; Yan, Y. P.
2014-12-01
Total-Routhian-surface calculations have been performed to investigate the shape evolutions of A ˜80 nuclei: Zr-8480,Sr-8076 , and Mo,8684 . Shape coexistences of spherical, prolate, and oblate deformations have been found in these nuclei. Particularly for the nuclei 80Sr and 82Zr , the energy differences between two shape-coexisting states are less than 220 keV. At high spins, the g9 /2 shell plays an important role in shape evolutions. It has been found that the alignment of the g9 /2 quasiparticles drives nuclei to be triaxial.
... Is Haglund’s Deformity? Haglund’s deformity is a bony enlargement on the back of the heel. The soft ... the Achilles tendon becomes irritated when the bony enlargement rubs against shoes. This often leads to painful ...
Kozin, Scott H; Zlotolow, Dan A
2015-10-01
Madelung deformity of the wrist is more common in females and is often associated with Leri Weill dyschondrosteosis, a mesomelic form of dwarfism. Patients with Madelung deformity often report wrist deformity resulting from the prominence of the relatively long ulna. The typical Madelung deformity is associated with a Vickers ligament that creates a tether across the volar-ulnar radial physis that restricts growth across this segment. The distal radius deforms in the coronal (increasing radial inclination) and the sagittal (increasing volar tilt) planes. There is lunate subsidence and the proximal carpal row adapts to the deformity by forming an upside-down pyramid shape or triangle. Treatment depends on the age at presentation, degree of deformity, and magnitude of symptoms. Mild asymptomatic deformity warrants a period of nonsurgical management with serial x-ray examinations because the natural history is unpredictable. Many patients never require surgical intervention. Progressive deformity in the young child with considerable growth potential remaining requires release of Vickers ligament and radial physiolysis to prevent ongoing deterioration Concomitant ulnar epiphysiodesis may be necessary. Advanced asymptomatic deformity in older children with an unacceptable-appearing wrist or symptomatic deformity are indications for surgery. A dome osteotomy of the radius allows 3-dimensional correction of the deformity. Positive radiographic and clinical results after dome osteotomy have been reported. PMID:26341718
NUCLEI AT HIGH ANGULAR MOMENTUM
Diamond, R.M.; Stephens, F.S.
1980-06-01
It appears that most nuclei show a compromise between purely collective and purely non-collective behavior at very high spins.non~collective behavior in nuclei has been seen only as high as 36 or 37{bar h}, at which point a more collective structure seems to develop. The concepts underlying the study of high angular momentum states are discussed. The factors that limit angular momentum in nuclei are considered. The currently emerging state of physics of very high spin states is reviewed. The detailed calculations currently made for high spin states are described, focusing not on the calculations themselves, but on the physical input to them and results that come out. Production of high-spin states using heavy-ion reactions is reviewed. Studies of {gamma}-rays de-exciting the evaporation residues from heavy-ion reactions are covered. Two types of {gamma} rays occur: those that cool the nucleus to or toward the yrast line, called "statistical," and those that are more or less parallel to the yrast line and remove the angular momentum, called "yrast~like." Collective rotation, in simplest form the motion of a deformed nucleus around an axis perpendicular to its symmetry axis, is also covered.
TOF-Bρ mass measurements of very exotic nuclides for astrophysical calculations at the NSCL
NASA Astrophysics Data System (ADS)
Matoš, M.; Estrade, A.; Amthor, M.; Aprahamian, A.; Bazin, D.; Becerril, A.; Elliot, T.; Galaviz, D.; Gade, A.; Gupta, S.; Lorusso, G.; Montes, F.; Pereira, J.; Portillo, M.; Rogers, A. M.; Schatz, H.; Shapira, D.; Smith, E.; Stolz, A.; Wallace, M.
2008-01-01
Atomic masses play a crucial role in many nuclear astrophysics calculations. The lack of experimental values for relevant exotic nuclides triggered a rapid development of new mass measurement devices around the world. The time-of-flight (TOF) mass measurements offer a complementary technique to the most precise one, Penning trap measurements (Blaum 2006 Phys. Rep. 425 1), the latter being limited by the rate and half-lives of the ions of interest. The NSCL facility provides a well-suited infrastructure for the TOF mass measurements of very exotic nuclei. At this facility, we have recently implemented a TOF-Bρ technique and performed mass measurements of neutron-rich nuclides in the Fe region, important for r-process calculations and for calculations of processes occurring in the crust of accreting neutron stars.
Distinctive exotic flavor and aroma compounds of some exotic tropical fruits and berries: a review.
Lasekan, Ola; Abbas, Kassim A
2012-01-01
The characteristic flavor of exotic tropical fruits is one of their most attractive attributes to consumers. In this article, the enormous diversity of exotic fruit flavors is reviewed. Classifying some of the exotic fruits into two classes on the basis of whether esters or terpenes predominate in the aroma was also attempted. Indeed, as far as exotic tropical fruits are concerned, the majority of fruits have terpenes predominating in their aroma profile. Some of the fruits in this group are the Amazonian fruits such as pitanga, umbu-caja, camu-camu, garcinia, and bacuri. The ester group is made up of rambutan, durians, star fruit, snake fruit, acerola, tamarind, sapodilla, genipap, soursop, cashew, melon, jackfruit, and cupuacu respectively. Also, the role of sulphur-volatiles in some of the exotic fruits is detailed. PMID:22591343
Injuries, envenomations and stings from exotic pets
Warwick, Clifford; Steedman, Catrina
2012-01-01
A variety of exotic vertebrate and invertebrate species are kept as ‘pets’ including fishes, amphibians (for example, frogs and toads), reptiles (turtles, crocodiles, lizards and snakes), birds, mammals (for example, primates, civets, and lions), and invertebrates (for example spiders, scorpions, and centipedes), and ownership of some of these animals is rising. Data for 2009–2011 suggest that the number of homes with reptiles rose by approximately 12.5%. Recent surveys, including only some of these animals, indicated that they might be present in around 18.6% of homes (equal to approximately 42 million animals of which around 40 million are indoor or outdoor fish). Many exotic ‘pets’ are capable of causing injury or poisoning to their keepers and some contacts prove fatal. We examined NHS Health Episode Statistics for England using selected formal categories for hospital admissions and bed days for 2004–2010 using the following categories of injury, envenomation or sting; bitten or struck by crocodile or alligator; bitten or crushed by other reptiles: contact with venomous snakes and lizards; contact with scorpions. Between 2004 and 2010 these data conservatively show a total of 760 full consultation episodes, 709 admissions and 2,121 hospital bed days were associated with injuries probably from exotic pets. Injuries, envenomations and stings from exotic pets constitute a small but important component of emerging medical problems. Greater awareness of relevant injuries and medical sequelae from exotic pet keeping may help medics formulate their clinical assessment and advice to patients. PMID:22843648
Injuries, envenomations and stings from exotic pets.
Warwick, Clifford; Steedman, Catrina
2012-07-01
A variety of exotic vertebrate and invertebrate species are kept as 'pets' including fishes, amphibians (for example, frogs and toads), reptiles (turtles, crocodiles, lizards and snakes), birds, mammals (for example, primates, civets, and lions), and invertebrates (for example spiders, scorpions, and centipedes), and ownership of some of these animals is rising. Data for 2009-2011 suggest that the number of homes with reptiles rose by approximately 12.5%. Recent surveys, including only some of these animals, indicated that they might be present in around 18.6% of homes (equal to approximately 42 million animals of which around 40 million are indoor or outdoor fish). Many exotic 'pets' are capable of causing injury or poisoning to their keepers and some contacts prove fatal. We examined NHS Health Episode Statistics for England using selected formal categories for hospital admissions and bed days for 2004-2010 using the following categories of injury, envenomation or sting; bitten or struck by crocodile or alligator; bitten or crushed by other reptiles: contact with venomous snakes and lizards; contact with scorpions. Between 2004 and 2010 these data conservatively show a total of 760 full consultation episodes, 709 admissions and 2,121 hospital bed days were associated with injuries probably from exotic pets. Injuries, envenomations and stings from exotic pets constitute a small but important component of emerging medical problems. Greater awareness of relevant injuries and medical sequelae from exotic pet keeping may help medics formulate their clinical assessment and advice to patients. PMID:22843648
Exotic Effects at the Charm Threshold and Other Novel Physics Topics at JLab-12 GeV
Brodsky, Stanley J.; /SLAC
2012-05-03
I briefly survey a number of novel hadron physics topics which can be investigated with the 12 GeV upgrade at J-Lab. The topics include new the formation of exotic heavy quark resonances accessible above the charm threshold, intrinsic charm and strangeness phenomena, the exclusive Sivers effect, hidden-color Fock states of nuclei, local two-photon interactions in deeply virtual Compton scattering, and non-universal antishadowing.
Coulomb excitation studies of shape coexistence in atomic nuclei
NASA Astrophysics Data System (ADS)
Görgen, Andreas; Korten, Wolfram
2016-02-01
Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei and allows measuring electromagnetic moments that can be directly related to the nuclear shape. The availability of radioactive ion beams (RIBs) at energies near the Coulomb barrier has made it possible to study shape coexistence in a variety of short-lived exotic nuclei. This review presents a short overview of the methods related to multi-step Coulomb excitation experiments, followed by a discussion of several examples. The focus is on two mass regions where recent Coulomb excitation experiments have contributed to the quantitative understanding of shape coexistence: nuclei with mass A≈ 70 near the N = Z line and nuclei with A ≈ 100 near neutron number N = 60. Experimental results are summarized and their significance for understanding shape coexistence is discussed. Experimental observables such as quadrupole moments and electromagnetic transition strengths represent furthermore important benchmarks for advancing theoretical nuclear structure models. With several new RIB facilities planned and under construction, Coulomb excitation will remain to be an important tool to extend the studies of nuclear shapes toward more exotic systems, and to obtain a more comprehensive and quantitative understanding of shape coexistence.
Fission and Properties of Neutron-Rich Nuclei
NASA Astrophysics Data System (ADS)
Hamilton, Joseph H.; Ramayya, A. V.; Carter, H. K.
2008-08-01
Opening session. Nuclear processes in stellar explosions / M. Wiescher. In-beam [symbol]-ray spectroscopy of neutron-rich nuclei at NSCL / A. Gade -- Nuclear structure I. Shell-model structure of neutron-rich nuclei beyond [symbol]Sn / A. Covello ... [et al.]. Shell structure and evolution of collectivity in nuclei above the [symbol]Sn core / S. Sarkar and M. S. Sarkar. Heavy-ion fusion using density-constrained TDHF / A. S. Umar and V. E. Oberacker. Towards an extended microscopic theory for upper-fp shell nuclei / K. P. Drumev. Properties of the Zr and Pb isotopes near the drip-line / V. N. Tarasov ... [et al.]. Identification of high spin states in [symbol] Cs nuclei and shell model calculations / K. Li ... [et al.]. Recent measurements of spherical and deformed isomers using the Lohengrin fission-fragment spectrometer / G. S. Simpson ... [et al.] -- Nuclear structure II. Nuclear structure investigation with rare isotope spectroscopic investigations at GSI / P. Boutachkov. Exploring the evolution of the shell structures by means of deep inelastic reactions / G. de Anaelis. Probing shell closures in neutron-rich nuclei / R. Krücken for the S277 and REX-ISOLDEMINIBALL collaborations. Structure of Fe isotopes at the limits of the pf-shell / N. Hoteling ... [et al.]. Spectroscopy of K isomers in shell-stabilized trans-fermium nuclei / S. K. Tandel ... [et al.] -- Radioactive ion beam facilities. SPIRAL2 at GANIL: a world leading ISOL facility for the next decade / S. Gales. New physics at the International Facility for Antiproton and Ion Research (FAIR) next to GSI / I. Augustin ... [et al.]. Radioactive beams from a high powered ISOL system / A. C. Shotter. RlKEN RT beam factory / T. Motobayashi. NSCL - ongoing activities and future perspectives / C. K. Gelbke. Rare isotope beams at Argonne / W. F. Henning. HRIBF: scientific highlights and future prospects / J. R. Beene. Radioactive ion beam research done in Dubna / G. M. Ter-Akopian ... [et al.] -- Fission I
Exotic Superconductivity in Correlated Electron Systems
Mu, Gang; Sandu, Viorel; Li, Wei; Shen, Bing
2015-05-25
Over the past decades, the search for high-T_{c} superconductivity (SC) and its novel superconducting mechanisms is one of the most challenging tasks of condensed matter physicists and material scientists, wherein the most striking achievement is the discovery of high-_{c} and unconventional superconductivity in strongly correlated 3d-electron systems, such as cuprates and iron pnictides/chalcogenides. Those exotic superconductors display the behaviors beyond the scope of the BCS theory (in the SC states) and the Landau-Fermi liquid theory (in the normal states). In general, such exotic superconductivity can be seen as correlated electron systems, where there are strong interplays among charge, spin, orbital, and lattice degrees of freedom. Thus, we focus on the exotic superconductivity in materials with correlated electrons in the present special issue.
Wildlife, exotic pets, and emerging zoonoses.
Chomel, Bruno B; Belotto, Albino; Meslin, François-Xavier
2007-01-01
Most emerging infectious diseases are zoonotic; wildlife constitutes a large and often unknown reservoir. Wildlife can also be a source for reemergence of previously controlled zoonoses. Although the discovery of such zoonoses is often related to better diagnostic tools, the leading causes of their emergence are human behavior and modifications to natural habitats (expansion of human populations and their encroachment on wildlife habitat), changes in agricultural practices, and globalization of trade. However, other factors include wildlife trade and translocation, live animal and bushmeat markets, consumption of exotic foods, development of ecotourism, access to petting zoos, and ownership of exotic pets. To reduce risk for emerging zoonoses, the public should be educated about the risks associated with wildlife, bushmeat, and exotic pet trades; and proper surveillance systems should be implemented. PMID:17370509
Issues and opportunities in exotic hadrons
Briceno, Raul A.; Cohen, Thomas D.; Coito, S.; Dudek, Jozef J.; Eichten, E.; Fischer, C. S.; Fritsch, M.; Gradl, W.; Jackura, A.; Kornicer, M.; et al
2016-04-01
The last few years have been witness to a proliferation of new results concerning heavy exotic hadrons. Experimentally, many new signals have been discovered that could be pointing towards the existence of tetraquarks, pentaquarks, and other exotic configurations of quarks and gluons. Theoretically, advances in lattice field theory techniques place us at the cusp of understanding complex coupled-channel phenomena, modelling grows more sophisticated, and effective field theories are being applied to an ever greater range of situations. Consequently, it is thus an opportune time to evaluate the status of the field. In the following, a series of high priority experimentalmore » and theoretical issues concerning heavy exotic hadrons is presented.« less
Wildlife, Exotic Pets, and Emerging Zoonoses1
Belotto, Albino; Meslin, François-Xavier
2007-01-01
Most emerging infectious diseases are zoonotic; wildlife constitutes a large and often unknown reservoir. Wildlife can also be a source for reemergence of previously controlled zoonoses. Although the discovery of such zoonoses is often related to better diagnostic tools, the leading causes of their emergence are human behavior and modifications to natural habitats (expansion of human populations and their encroachment on wildlife habitat), changes in agricultural practices, and globalization of trade. However, other factors include wildlife trade and translocation, live animal and bushmeat markets, consumption of exotic foods, development of ecotourism, access to petting zoos, and ownership of exotic pets. To reduce risk for emerging zoonoses, the public should be educated about the risks associated with wildlife, bushmeat, and exotic pet trades; and proper surveillance systems should be implemented. PMID:17370509
Exotic Superconductivity in Correlated Electron Systems
Mu, Gang; Sandu, Viorel; Li, Wei; Shen, Bing
2015-05-25
Over the past decades, the search for high-Tc superconductivity (SC) and its novel superconducting mechanisms is one of the most challenging tasks of condensed matter physicists and material scientists, wherein the most striking achievement is the discovery of high-c and unconventional superconductivity in strongly correlated 3d-electron systems, such as cuprates and iron pnictides/chalcogenides. Those exotic superconductors display the behaviors beyond the scope of the BCS theory (in the SC states) and the Landau-Fermi liquid theory (in the normal states). In general, such exotic superconductivity can be seen as correlated electron systems, where there are strong interplays among charge, spin, orbital,more » and lattice degrees of freedom. Thus, we focus on the exotic superconductivity in materials with correlated electrons in the present special issue.« less
Shell model for warm rotating nuclei
Matsuo, M.; Yoshida, K.; Dossing, T.
1996-12-31
Utilizing a shell model which combines the cranked Nilsson mean-field and the residual surface and volume delta two-body forces, the authors discuss the onset of rotational damping in normal- and super-deformed nuclei. Calculation for a typical normal deformed nucleus {sup 168}Yb indicates that the rotational damping sets in at around 0.8 MeV above the yrast line, and about 30 rotational bands of various length exists at a given rotational frequency, in overall agreement with experimental findings. It is predicted that the onset of rotational damping changes significantly in different superdeformed nuclei due to the variety of the shell gaps and single-particle orbits associated with the superdeformed mean-field.
Advances in exotic mammal clinical therapeutics.
Hawkins, Michelle G
2015-05-01
It is important that veterinarians treating exotic companion mammals stay abreast of the latest developments relating to medications and drug delivery approaches for safety, efficacy and welfare issues. Sustained release formulations of commonly used drugs as well as newer routes for administration of therapeutic agents allow the veterinarian treating exotic companion mammals to reduce the stress associated with drug administration. Interactions can occur between vehicle and drugs when formulations are compounded, therefore research studies are warranted regarding potential problems associated with these formulations. PMID:25902274
Exotic statistics of leapfrogging vortex rings.
Niemi, Antti J
2005-04-01
The leapfrogging motion of vortex rings is a three-dimensional version of the motion that in two dimensions leads to exotic exchange statistics. The statistical phase factor can be computed using the hydrodynamical Euler equation, which suggests that three-dimensional exotic exchange statistics is a common property of vortex rings in a variety of quantum liquids and gases. Potential applications range from helium superfluids to Bose-Einstein condensed alkali gases, metallic hydrogen in its liquid phases, and maybe even nuclear matter in extreme conditions. PMID:15903923
{alpha}-decay studies of the exotic N=125, 126, and 127 isotones
Xu Chang; Ren Zhongzhou
2007-08-15
The {alpha}-decay half-lives of the exotic N=125, 126, and 127 isotones (Po, Rn, Ra, Th, and U) are systematically studied by the density-dependent cluster model (DDCM). The influence of the neutron shell closure N=126 on the {alpha}-cluster formation and penetration probabilities is analyzed and discussed in detail. By combining the DDCM and a two-level microscopic model together, the experimental half-lives of {alpha} transitions to both the ground state and the excited state in the daughter nuclei are reproduced very well.
Study Of The Scattering Of Halo Nuclei Around The Coulomb Barrier
Acosta, L.; Sanchez-Benitez, A. M.; Garcia-Ramos, J. E.; Gomez, M. E.; Martel, I.; Perez-Bernal, F.; Rodriguez-Quintero, J.; Cubero, M.; Escrig, D.; Alcorta, M.; Borge, M. J. G.; Madurga, M.; Maira-Vidal, A.; Reillo, E.; Tengblad, O.; Fernandez-Garcia, J. P.; Lay, J. A.; Moro, A. M.; Andres, M. V.; Cortes, M. A.
2011-06-01
During the past ten years the present collaboration has carried out several experiments related with the study of radioactive nuclei. One of the topics in which we have centered our research, is the scattering of halo nuclei at energies around the Coulomb barrier. As part of this study, we present in this work a review of the results obtained from the scattering of {sup 6}He, {sup 11}Be and {sup 11}Li. The presence of a ''halo'' in these exotic nuclei is found to have a striking effect on the dynamics of these reactions, making their study an interesting experimental problem and a challenge for existing reaction theories.
Open s d -shell nuclei from first principles
NASA Astrophysics Data System (ADS)
Jansen, G. R.; Schuster, M. D.; Signoracci, A.; Hagen, G.; Navrátil, P.
2016-07-01
We extend the ab initio coupled-cluster effective interaction (CCEI) method to open-shell nuclei with protons and neutrons in the valence space and compute binding energies and excited states of isotopes of neon and magnesium. We employ a nucleon-nucleon and three-nucleon interaction from chiral effective field theory evolved to a lower cutoff via a similarity renormalization group transformation. We find good agreement with experiment for binding energies and spectra, while charge radii of neon isotopes are underestimated. For the deformed nuclei 20Ne and 24Mg, we reproduce rotational bands and electric quadrupole transitions within uncertainties estimated from an effective field theory for deformed nuclei, thereby demonstrating that collective phenomena in s d -shell nuclei emerge from complex ab initio calculations.
Open sd-shell nuclei from first principles
Jansen, Gustav R.; Signoracci, Angelo J.; Hagen, Gaute; Navratil, Petr
2016-07-05
We extend the ab initio coupled-cluster e ective interaction (CCEI) method to open-shell nuclei with protons and neutrons in the valence space, and compute binding energies and excited states of isotopes of neon and magnesium. We employ a nucleon-nucleon and three-nucleon interaction from chiral e ective eld theory evolved to a lower cuto via a similarity renormalization group transformation. We nd good agreement with experiment for binding energies and spectra, while charge radii of neon isotopes are underestimated. For the deformed nuclei 20Ne and 24Mg we reproduce rotational bands and electric quadrupole transitions within uncertainties estimated from an e ectivemore » eld theory for deformed nuclei, thereby demonstrating that collective phenomena in sd-shell nuclei emerge from complex ab initio calculations.« less
Anomaly of the moment of inertia of shape transitional nuclei
Gupta, J. B.; Hamilton, J. H.
2011-06-15
The change in the structure of the collective levels with spin angular momentum in atomic nuclei is often expressed in terms of the classical concepts of the kinematic and the dynamic moments of inertia varying with spin. For the well deformed even-even nuclei the kinematic moment of inertia increases with spin up to 10%-20%, at say I{sup {pi}} = 12{sup +}. However, for the shape transitional nuclei, or almost spherical nuclei, it increases with spin much faster. The pitfalls of using the rotor model form of kinematic moment of inertia in such cases are pointed out here. Alternative methods of extracting the nuclear structure information are explored. The important role of the ground state deformation is illustrated. The use of the power index formula for evaluating the effective moment of inertia, free from the assumption of the rotor model, is described.
Angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei
Severijns, N.; Golovko, V.V.; Kraev, I.S.; Phalet, T.; Belyaev, A.A.; Lukhanin, A.A.; Noga, V.I.; Erzinkyan, A.L.; Parfenova, V.P.; Eversheim, P.-D.; Herzog, P.; Tramm, C.; Filimonov, V.T.; Toporov, Yu.G.; Zotov, E.; Gurevich, G.M.; Rusakov, A.V.; Vyachin, V.N.; Zakoucky, D.
2005-04-01
The anisotropy in the angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei, which are among the strongest deformed {alpha} emitters, was measured. Large {alpha} anisotropies have been observed for all three nuclei. The results are compared with calculations based on {alpha}-particle tunneling through a deformed Coulomb barrier.
Fast electric dipole transitions in Ra-Ac nuclei
Ahmad, I.
1985-01-01
Lifetime of levels in /sup 225/Ra, /sup 225/Ac, and /sup 227/Ac have been measured by delayed coincidence techniques and these have been used to determine the E1 gamma-ray transition probabilities. The reduced E1 transition probabilities. The reduced E1 transition probabilities in /sup 225/Ra and /sup 225/Ac are about two orders of magnitude larger than the values in mid-actinide nuclei. On the other hand, the E1 rate in /sup 227/Ac is similar to those measured in heavier actinides. Previous studies suggest the presence of octupole deformation in all the three nuclei. The present investigation indicates that fast E1 transitions occur for nuclei with octupole deformation. However, the studies also show that there is no one-to-one correspondence between E1 rate and octupole deformation. 13 refs., 4 figs.
Orientations of recrystallization nuclei developed in columnar-grained Ni at triple junctions
NASA Astrophysics Data System (ADS)
Xu, C. L.; Huang, S.; Zhang, Y. B.; Wu, G. L.; Liu, Q.; Jensen, D. Juul
2015-04-01
A high purity columnar grained nickel sample with a strong <001> fiber texture was cold rolled to 50% reduction in thickness, followed by annealing at different temperatures. Optical microscopy was used to depict the grain boundaries prior to annealing and to detect nuclei formed on grain boundaries after annealing. Electron backscatter diffraction was performed to characterize the orientations of the nuclei and the deformed grains. Hardness tests were conducted at deformed grains. The potentials of triple junctions as preferential nucleation sites, the influence of deformation differences between adjacent grains on nucleation and orientation relationships between nuclei and parent matrix are analyzed.
[Microbiological conservation medicine and exotic pets].
Hassl, Andreas
2004-01-01
The keeping and the breeding of exotic pets in privacy is a hobby with increasing popularity in industrialised countries. The growing demand for animals usually imported from the tropics, the growing demand for unprofessionally bred feeder organisms, and the increasing number of cases of faulty caring behaviour lead to the creation of new infectiological niches in the interface between exotic pet--nurse--feed--vivarium. These niches are filled preferably by ubiquitous, facultative pathogenic, stress- and age-deduced opportunists with a broad host spectrum. On the one hand these extraordinary germ faunas, relating to their compositions, may generate broad relevance in human medicine, lead to bizarre clinical pictures in specific cases, and may contribute to a reduction of the mean span of life of exotic pets kept in human care. On the other hand the quantitative composition of the fauna may also be a direct measure of the degree of stress the pets are suffering in captivity. Thus, a professional designation of the germ fauna of an exotic pet may contribute to an optimisation of the captivity conditions. PMID:15683044
CMS supersymmetry and exotic Higgs results
NASA Astrophysics Data System (ADS)
Yohay, R.; CMS Collaboration
2016-07-01
A selection of results covering searches for supersymmetric particles and exotic decays of the Higgs boson are presented. These results are based on 8 TeV proton-proton collision data collected by the Compact Muon Solenoid experiment at the Large Hadron Collider.
Exotic Gauge Bosons in the 331 Model
Romero, D.; Ravinez, O.; Diaz, H.; Reyes, J.
2009-04-30
We analize the bosonic sector of the 331 model which contains exotic leptons, quarks and bosons (E,J,U,V) in order to satisfy the weak gauge SU(3){sub L} invariance. We develop the Feynman rules of the entire kinetic bosonic sector which will let us to compute some of the Z(0)' decays modes.
Phenology of cheatgrass and associated exotic weeds
Technology Transfer Automated Retrieval System (TEKTRAN)
Cheatgrass (Bromus tectorum), is an exotic, highly invasive annual grass that has dramatically changed the aspect and ecological functions of vast areas of formerly big sagebrush/bunchgrass and salt desert rangelands in the Intermountain west. Cheatgrass increases the chance of ignition, rate of spr...
Exotic heavy-quark states at Belle
NASA Astrophysics Data System (ADS)
Wang, Xiaolong; Belle Collaboration
2016-03-01
The search for multi-quark states beyond the meson (quark-antiquark) and baryon (three-quark) has resulted in the discovery of many new exotic states of matter, starting with the X(3872) discovery by Belle in 2003. We report selected recent results on searches for such states at Belle. supported by the Department of Energy Office of Science.
Halos in a deformed relativistic Hartree-Bogoliubov theory in continuum
Li Lulu; Meng Jie; Ring, P.; Zhao Enguang; Zhou Shangui
2012-10-20
In this contribution we present some recent results about neutron halos in deformed nuclei. A deformed relativistic Hartree-Bogoliubov theory in continuumhas been developed and the halo phenomenon in deformed weakly bound nuclei is investigated. 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. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nuclei {sup 42}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 existence of halos in deformed nuclei and for the occurrence of this decoupling effect are discussed.
Bohr Hamiltonian with a deformation-dependent mass term for the Davidson potential
Bonatsos, Dennis; Georgoudis, P. E.; Lenis, D.; Minkov, N.; Quesne, C.
2011-04-15
Analytical expressions for spectra and wave functions are derived for a Bohr Hamiltonian, describing the collective motion of deformed nuclei, in which the mass is allowed to depend on the nuclear deformation. Solutions are obtained for separable potentials consisting of a Davidson potential in the {beta} variable, in the cases of {gamma}-unstable nuclei, axially symmetric prolate deformed nuclei, and triaxial nuclei, implementing the usual approximations in each case. The solution, called the deformation-dependent mass (DDM) Davidson model, is achieved by using techniques of supersymmetric quantum mechanics (SUSYQM), involving a deformed shape invariance condition. Spectra and B(E2) transition rates are compared to experimental data. The dependence of the mass on the deformation, dictated by SUSYQM for the potential used, reduces the rate of increase of the moment of inertia with deformation, removing a main drawback of the model.
Ground State Properties and Bubble Structure of Synthesized Superheavy Nuclei
NASA Astrophysics Data System (ADS)
Singh, S. K.; Ikram, M.; Patra, S. K.
2013-01-01
We calculate the ground state properties of recently synthesized superheavy elements (SHEs) from Z = 105-118 along with the predicted proton magic Z = 120. The relativistic and nonrelativistic mean field formalisms are used to evaluate the binding energy (BE), charge radius, quadrupole deformation parameter and the density distribution of nucleons. We analyzed the stability of the nuclei based on BE and neutron to proton ratio. We also studied the bubble structure which reveals the special features of the superheavy nuclei.
Isovector pairing and quartet condensation in N=Z nuclei
Sandulescu, N.; Negrea, D.; Dukelsky, J.; Johnson, C. W.
2012-11-20
We introduce and study a quartet condensate model (QCM) to treat the isovector pairing correlations in N=Z nuclei, by conserving the particle number and the total spin and isospin in the ground state of such nuclei. For the calculations we choose different isovector pairing forces acting on spherical and axially deformed single particle states. The results show that the QCM model describes very well the isovector pairing correlations for nuclear systems with N=Z.
RECOVERY OF EXOTIC ALLELES IN ENHANCED TROPICAL YELLOW GERMPLASM
Technology Transfer Automated Retrieval System (TEKTRAN)
Enhancement of overall diversity levels and the incorporation of new favorable traits are major benefits of using exotic germplasm in elite breeding programs. Agronomic deficiencies and poor adaptation often limits use of exotic germplasm in plant breeding programs. To introgress exotic alleles into...
Exotic annual grass alters fuel amounts, continuity and moisture content
Technology Transfer Automated Retrieval System (TEKTRAN)
1. Invasion by exotic plants are one of the most serious threats to native plant communities, biodiversity, and ecosystem functioning. Of particular concern are exotic plants that alter disturbance regimes. Exotic annual grasses are believed to increase wildfire frequency to the detriment of nativ...
Recovery of Exotic Alleles in Enhanced Tropical Yellow Germplasm
Technology Transfer Automated Retrieval System (TEKTRAN)
Enhancement of overall diversity levels and the incorporation of new favorable traits are major benefits of using exotic germplasm in elite breeding programs. Agronomic deficiencies and poor adaptation often limits use of exotic germplasm in plant breeding programs. To introgress exotic alleles into...
Survey of Reflection-Asymmetric Nuclear Deformations
NASA Astrophysics Data System (ADS)
Olsen, Erik; Birge, Noah; Erler, Jochen; Nazarewicz, Witek; Perhac, Alex; Schunck, Nicolas; Stoitsov, Mario; Nuclei Collaboration
2015-10-01
Due to spontaneous symmetry breaking it is possible for a nucleus to have a deformed shape in its ground state. It is theorized that atoms whose nuclei have reflection-asymmetric or pear-like deformations could have non-zero electric dipole moments (EDMs). Such a trait would be evidence of CP-violation, a feature that goes beyond the Standard Model of Physics. It is the purpose of this project to predict which nuclei exhibit a reflection-asymmetric deformation and which of those would be the best candidates for an EDM measuring experiment. Using nuclear Density Functional Theory along with the new computer code AxialHFB and massively parallel computing we calculated ground state nuclear properties for thousands of even-even nuclei across the nuclear chart: from light to superheavy and from stable to short-lived systems. Six different Energy Density Functionals (EDFs) were used to assess systematic errors in our calculations. Overall, 140 even-even nuclei (near and among the lantanides and actinides and in the superheavy region near N = 184) were predicted by all 6 EDFs to have a pear-like deformation. The case of 112Xe also proved curious as it was predicted by 5 EDFs to have a pear-like deformation despite its proximity to the two-proton drip line. Deceased.
Quantum effects in low-energy photofission of heavy nuclei
Tsipenyuk, Y.M.; Ostapenko, Y.B.; Smirenkin, G.N.; Soldatov, A.S.
1984-09-01
The article is devoted to quantum effects in highly deformed nuclei and the related features of the fission mechanism in the low-energy photofission of heavy nuclei. The following questions are considered: the spectrum of transition states (fission channels), the symmetry of the nuclear configuration in the deformation process, the features of the passage through the barrier due to the existence in the second well of quasistationary states of fissile and nonfissile modes, the isomeric-shelf phenomenon in deep sub-barrier fission, and the relation between the fragment mass distribution and the structure of the fission barrier.
Existence of Exotic Torus Isomer States and Their Precession Motions
NASA Astrophysics Data System (ADS)
Ichikawa, Takatoshi; Matsuyanagi, Kenichi; Maruhn, Joachim A.; Itagaki, Naoyuki
We systematically investigate the existence of exotic high-spin torus isomers and their precession motions for a series of N = Z even-even nuclei from 28Si to 56Ni. For this purpose, we use the cranked three-dimensional Hatree-Fock (HF) method in a systematic search for high-spin torus isomers and the three-dimensional time-dependent Hatree-Fock (TDHF) method for describing the precession motion of the torus isomer. We obtain high-spin torus isomers in 36Ar, 40Ca, 44Ti, 48Cr, and 52Fe. The emergence of the torus isomers is associated with the alignments of single-particle angular momenta, which is the same mechanism as found in 40Ca. We find that all the obtained torus isomers execute the precession motion at least two rotational periods. The moment of inertia about a perpendicular axis, which characterizes the precession motion, is found to be close to the classical rigid-body value.
Elastic scattering and reactions of light exotic beams
NASA Astrophysics Data System (ADS)
Keeley, N.; Alamanos, N.; Kemper, K. W.; Rusek, K.
2009-10-01
The present work provides a literature survey of elastic scattering of exotic nuclei from 6He to 17F. It presents a set of definitions that allow different analyses to be put into a common language. A calculational approach is proposed that yields consistent results across different beams and targets so that conclusions concerning the influence of virtual and real breakup as well as transfer couplings on the elastic scattering may be drawn. Calculations of elastic scattering around the Coulomb barrier are emphasised, employing a Pb target whose large Z allows the interplay between nuclear and Coulomb forces to be exploited to maximise possible effects arising from proton or neutron haloes or skins. A series of test calculations is performed and where possible compared to data, demonstrating that there are instances where coupling to transfer channels can have a large effect on the elastic scattering angular distributions. By careful choice of target/beam combination, different aspects of the coupling effects may be emphasised.
Fabian, Andrew C.
1999-01-01
Active galactic nuclei are the most powerful, long-lived objects in the Universe. Recent data confirm the theoretical idea that the power source is accretion into a massive black hole. The common occurrence of obscuration and outflows probably means that the contribution of active galactic nuclei to the power density of the Universe has been generally underestimated. PMID:10220363
Microscopic analysis of pear-shaped nuclei
NASA Astrophysics Data System (ADS)
Nomura, K.
2015-10-01
We analyze the quadrupole-octupole collective states based on the microscopic energy density functional framework. By mapping the deformation constrained self-consistent axially symmetric mean-field energy surfaces onto the equivalent Hamiltonian of the sd f interacting boson model (IBM), that is, onto the energy expectation value in the boson coherent state, the Hamiltonian parameters are determined. The resulting IBM Hamiltonian is used to calculate excitation spectra and transition rates for the positive- and negative-parity collective states in nuclei characteristic for octupole deformation and collectivity. Consistently with the empirical trend, the microscopic calculation based on the systematics of β2 - β3 energy maps, the resulting low-lying negative-parity bands and transition rates show evidence of a shape transition between stable octupole deformation and octupole vibrations characteristic for β3-soft potentials.
Ground state properties of superheavy nuclei with Z=117 and Z=119
Ren Zhongzhou; Chen Dinghan; Xu Chang
2006-11-02
We review the current studies on the ground-state properties of superheavy nuclei. It is shown that there is shape coexistence for the ground state of many superheavy nuclei from different models and many superheavy nuclei are deformed. This can lead to the existence of isomers in superheavy region and it plays an important role for the stability of superheavy nuclei. Some new results on Z=117 and Z=119 isotopes are presented. The agreement between theoretical results and experimental data clearly demonstrates the validity of theoretical models for the ground-state properties of superheavy nuclei.
Allowance for the shell structure of colliding nuclei in the fusion-fission process
Litnevsky, V. L.; Kosenko, G. I.; Ivanyuk, F. A.; Pashkevich, V. V.
2011-07-15
The motion of two nuclei toward each other in fusion-fission reactions is considered. The state of the system of interacting nuclei is specified in terms of three collective coordinates (parameters). These are the distance between the centers of mass of the nuclei and the deformation parameter for each of them (the nose-to-nose orientation of the nuclei is assumed). The evolution of collective degrees of freedom of the system is described by Langevin equations. The energies of the Coulomb and nuclear (Gross-Kalinovsky potential) interactions of nuclei are taken into account in the potential energy of the system along with the deformation energy of each nucleus with allowance for shell effects. The motion of nuclei toward each other are calculated for two reaction types: reactions involving nuclei that are deformed ({sub 42}{sup 100}Mo + {sub 42}{sup 100}Mo {yields} {sub 84}{sup 200}Po) and those that are spherical ({sub 82}{sup 208}Pb + {sub 8}{sup 18}O {yields} {sub 90}{sup 226}Th) in the ground state. It is shown that the shell structure of interacting nuclei affects not only the fusion process as a whole (fusionbarrier height and initial-reaction-energy dependence of the probability that the nuclei involved touch each other) but also the processes occurring in each nucleus individually (shape of the nuclei and their excitation energies at the point of touching).
Bunnell, W P
1986-12-01
Spinal deformity is a relatively common disorder, particularly in teenage girls. Early detection is possible by a simple, quick visual inspection that should be a standard part of the routine examination of all preteen and teenage patients. Follow-up observation will reveal those curvatures that are progressive and permit orthotic treatment to prevent further increase in the deformity. Spinal fusion offers correction and stabilization of more severe degrees of scoliosis. PMID:3786010
Cluster Features of Normal-, Super- and Hyperdeformed nuclei
Adamian, G.G.; Antonenko, N.V.; Kuklin, S.N.
2005-11-21
It is shown that an important mode of nuclear excitations in different processes like as cluster radioactivity, parity splitting in normal deformed bands, decay out phenomenon of the yrast superdeformed states in the heavy nuclei and formation of super- and hyper-deformed states in induced fission and heavy ion reactions is related to the motion in charge (mass) asymmetry coordinate. With the suggested cluster model one can try to unify all phenomena mentioned above.
Electron microscopy of some exotic materials
Mitchell, T.E.
1998-09-01
Just about every material has been looked at under the microscope, either out of pure inquisitiveness or the need to relate the microstructure to its properties. Some of these materials are mundane, like steels or glass or polyethylene; others are so-called advanced, such as intermetallics, silicon nitride or zirconia; yet others might be called exotic whether they be martian rocks, high temperature superconductors, fullerenes, diamonds, or the latest thin film device. Many exotic materials are important in Los Alamos, not only weapons materials such as actinides, tritium and explosives, but also civilian materials for energy applications. Here the author will report briefly on plutonium and uranium, on rhenium disilicide, and on Cu-Nb nanolayered composites.
RIB Production at LNL: the EXOTIC Facility
NASA Astrophysics Data System (ADS)
Marco, Mazzocco
2016-04-01
Nuclear reactions involving radioactive isotopes are extremely relevant in several astrophysical scenarios, from the Big-Bang Nucleosynthesis to Supernovae explosions. In this contribution the production of Radioactive Ion Beams (RIBs) by means of the in-flight technique is reviewed. In particular, the use of direct reactions in inverse kinematics for the production of light weakly-bound RIBs by means of the facility EXOTIC at INFN-LNL (Italy) will be described in detail.
Further examination of prolate-shape dominance in nuclear deformation
Hamamoto, Ikuko; Mottelson, Ben R.
2009-03-15
The observed almost complete dominance of prolate over oblate deformations in the ground states of deformed even-even nuclei is related to the splitting of high l''surface'' orbits in the Nilsson diagram: on the oblate side the occurrence of numerous strongly avoided crossings which reduce the fanning out of the low {lambda} orbits, while on the prolate side the same interactions increase the fanning out. It is further demonstrated that the prolate dominance is rather special for the restricted particle number of available nuclei and is not generic for finite systems with mean-field potentials resembling those in atomic nuclei.
Exotic leptoquarks from superstring derived models
Elwood, J.K.; Faraggi, A.E.
1997-03-01
The H1 and ZEUS collaborations have recently reported a significant excess of e{sup +}p {r_arrow} e{sup +} jet events at high Q{sup 2}. While there exists insufficient data to conclusively determine the origin of this excess, one possibility is that it is due to a new leptoquark at mass scale around 200 GeV. We examine the type of leptoquark states that exist in superstring derived standard-like models, and show that, while these models may contain the standard leptoquark states which exist in Grand Unified Theories, they also generically contain new and exotic leptoquark states with fractional lepton number, {+-}1/2. In contrast to the traditional GUT-type leptoquark states, the couplings of the exotic leptoquarks to the Standard Model states are generated after the breaking of U(1){sub B-L}. This important feature of the exotic leptoquark states may result in local discrete symmetries which forbid some of the undesired leptoquark couplings. We examine these couplings in several models and study the phenomenological implications. The flavor symmetries of the superstring models are found to naturally suppress leptoquark flavor changing processes.
Infectious threats from exotic pets: dermatological implications.
Rosen, Ted; Jablon, Jennifer
2003-04-01
Zoonoses are diseases that can be transmitted from animals to humans. More than 250 distinct zoonoses have been described in the literature. It is estimated that 56% of United States households contain at least one pet, and although considerable research has been performed regarding the more common household animals including dogs, cats, small birds, and rodents, surprisingly little is known about the zoonotic hazards of owning the more exotic pets. According to the 1997 USPHS/IDSA Report on the Prevention of Opportunistic Infections in Persons Infected with Human Immunodeficiency Virus, the immunocompromised patient should avoid contact with feces-laden soil, litter boxes, reptiles, most pet birds, and any animal less than 6 months old . It has also been documented that because of their inquisitive nature, children are at even higher risk for infection from animals than adolescents or immunocompetent adults. In this article the authors have reviewed the available data regarding hazards associated with the hedgehog, flying squirrel, iguana, chinchilla, and cockatoo. With the growing popularity of such exotic pets, further observation and research is warranted. Physicians need to be aware of the possibility of zoonotic disease related to exotic pet ownership, and they should address this issue when obtaining a history and formulating a differential diagnosis of cutaneous lesions suggestive of such illnesses. PMID:12757244
Exotic Forms of Silicon for Energy Applications
NASA Astrophysics Data System (ADS)
Taylor, P. Craig
2015-03-01
Over the last few decades many exotic forms of carbon, such as carbon-60, carbon nanotubes, and graphene, have generated novel scientific discoveries and revolutionized many important applications. Similar potentially transformative breakthroughs may be expected with exotic forms of silicon. Such structures include, but are not necessarily limited to, (1) those formed under high pressure that are metastable at ambient pressure, (2) single layers of Si (silicene), (2) clathrate Si, which has been studied for superconducting and thermoelectric properties but not in any detail for semiconductor applications, (3) nanostructured forms of Si (nanodots and nanowires), including those composed of diamond Si, (4) porous Si, and (5) any other structures that differ in their structural, optical or electronic properties from bulk diamond Si. Silicon is an abundant, non-toxic element around which an advanced technology exists for semiconducting devices based on diamond Si. One of these exotic forms of Si could form the basis for the next revolution in electronics or even opto-electronics, since some forms exhibit direct, or nearly direct, band gaps. Recent results toward producing pure and dopable semiconductors out of Si nanodots imbedded in amorphous matrices and in clathrate Si and clathrate Si-Ge alloys will be discussed. The author acknowledges important collaborations with R. T. Collins, C. A. Koh, L. Krishna, M. Lusk, and P. Stradins. DOE SUNSHOT program, under Contract DE-EE0005326 and by the NSF MRSEC program under Grant DMR-0820518.
Recent results on giant dipole resonance decays in highly excited nuclei
Snover, K.A.
1991-12-31
Some recent results on Giant Dipole Resonance (GDR) decays in highly excited, equilibrated nuclei, are discussed based primarily on work done at Seattle. Four sections address the following topics: oblate shapes of rotating, highly excited Zr--Mo nuclei; adiabatic versus `motionally narrowed` GDR decay; large spin-driven deformations observed in hot medium-mass nuclei; and search for entrance channel effects in GDR decay following {sup 58}Ni {plus} {sup 92}Zr fusion. 22 refs.
Recent results on giant dipole resonance decays in highly excited nuclei
Snover, K.A.
1991-01-01
Some recent results on Giant Dipole Resonance (GDR) decays in highly excited, equilibrated nuclei, are discussed based primarily on work done at Seattle. Four sections address the following topics: oblate shapes of rotating, highly excited Zr--Mo nuclei; adiabatic versus motionally narrowed' GDR decay; large spin-driven deformations observed in hot medium-mass nuclei; and search for entrance channel effects in GDR decay following [sup 58]Ni [plus] [sup 92]Zr fusion. 22 refs.
Delayed and In-beam Spectroscopy on Francium and Astatine Nuclei at the Proton Drip Line
NASA Astrophysics Data System (ADS)
Uusitalo, J.; Jakobsson, U.
2011-11-01
Delayed and in-beam spectroscopy on francium and astatine nuclei at and beyond the proton drip line has been performed. In neutron deficient astatine nuclei a shift to deformed shapes as a function of decreasing neutron has been obtained. In neutron deficient francium isotope the same shift is evident.
Delayed and In-beam Spectroscopy on Francium and Astatine Nuclei at the Proton Drip Line
Uusitalo, J.; Jakobsson, U.; Collaboration: RITU-Gamma Gollaboration
2011-11-30
Delayed and in-beam spectroscopy on francium and astatine nuclei at and beyond the proton drip line has been performed. In neutron deficient astatine nuclei a shift to deformed shapes as a function of decreasing neutron has been obtained. In neutron deficient francium isotope the same shift is evident.
Halo Nuclei: Stepping Stones Across the Dripline
NASA Astrophysics Data System (ADS)
Simon, Haik
2013-08-01
The availability of intense secondary beams in conjunction with efficient detection setups allows for a production and study of the most extreme nuclear systems, in terms of asymmetry of proton and neutron number, in the continuum. They can be produced via transfer and knockout reactions, depending on beam energies, with beams of nuclei close to the driplines, exhibiting exotic properties themselves, as seeds. These nuclear open quantum systems far from the valley of beta stability challenge nuclear structure theory being as well as reaction theory that tries to describe their production mechanisms. Due to their strong clustering they exhibit a rather clean few-body character. From experiments momentum distributions, relative energy spectra, and spin alignment during the reaction can be determined, which leads to the observation of energy and angular correlations as well as dependent quantities like e.g. the profile function denoting a momentum width in dependence of relative energy. They are determined from momentum vectors of fragments and gamma radiation leaving the reaction zone. The link to intrinsic properties of these unbound systems has to be explored by gathering precise knowledge of the properties of the seed nuclei and compare them to the structures observed in the continuum. In this paper I will exemplify the above-mentioned methods, and apply them particularly to light systems like 10He, 10-13Li, and neutron-rich Beryllium systems. Furthermore, perspectives for the 7H and heavy Oxygen systems are discussed.
Lubich, Carol; Krenzelok, Edward P
2009-01-01
Emergency departments throughout the USA may have some familiarity with the management of envenomation from indigenous snake species such as Crotalinae (rattlesnakes) and Micrurus (coral snakes). However, venomous species may include exotic reptiles whose bites pose substantial treatment challenges due to both a lack of experience and the difficulty in obtaining antivenoms. Two pet cobra envenomation incidents illustrate the challenges that face emergency departments, especially in urban settings, that are confronted with these exposures. It is important for emergency departments to be aware of the large underground presence of exotic venomous reptile pets and to utilise the expertise of regional poison centres that will also assist in the procurement of exotic antivenoms. PMID:21686401
Mitigating exotic impacts: restoring deer mouse populations elevated by an exotic food subsidy.
Pearson, Dean E; Fletcher, Robert J
2008-03-01
The threat posed by exotic organisms to native systems has led to extensive research on exotic invaders, yet management of invasives has progressed relatively slowly. This is partly due to poor understanding of how exotic species management influences native organisms. To address this shortfall, we experimentally evaluated the efficacy of an invasives management tool for restoring native deer mouse (Peromyscus maniculatus) populations elevated by exotic species. The exotic insects, Urophora spp., were introduced in North America for biological control of the Eurasian invader, spotted knapweed (Centaurea maculosa), but instead of controlling C. maculosa, Urophora have become an important food resource that doubles P. maniculatus populations, with substantial indirect effects on other organisms. We hypothesized that herbicide suppression of Urophora's host plant would reduce the Urophora food resource and restore P. maniculatus populations to natural levels. Prior to treatment, mouse populations did not differ between controls and treatments, but following treatment, P. maniculatus were half as abundant where treatment reduced Urophora. Peromyscus maniculatus is insensitive to direct herbicide effects, and herbicide-induced habitat changes could not explain the P. maniculatus response. Treatment-induced reductions of the Urophora food resource offered the most parsimonious explanation for the mouse response: Multistate mark-recapture models indicated that P. maniculatus survival declined where Urophora were removed, and survival rates were more correlated with variation in population size than movement rates. Other demographic and reproductive parameters (sex ratios, reproductive status, pregnancy rates, and juvenile recruitment) were unaffected by treatment. These results suggest the Urophora biocontrol elevated P. maniculatus survival, and the herbicide treatment restored mouse populations by removing the exotic food and reducing survival. This work illustrates the
NASA Astrophysics Data System (ADS)
Martini, M.; Péru, S.; Hilaire, S.; Goriely, S.; Lechaftois, F.
2016-07-01
Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the E 1 γ -ray strength function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation based on the finite-range Gogny force. This approach is applied to even-even nuclei, the strength function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cutoff energy introduced in the 2-quasiparticle (2 -q p ) excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the E 1 strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically ˜2 MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard 2 -q p QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to somewhat similar predictions of the E 1 strength, both at low energies and for exotic neutron-rich nuclei. Predictions of γ -ray strength functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
Brown, R.D. Jr.
1990-01-01
Displaced or deformed rock units and landforms record the past 2 m.y. of faulting, folding, uplift, and subsidence in California. Properly interpreted, such evidence provides a quantitative basis for predicting future earthquake activity and for relating many diverse structures and landforms to the 5 cm/yr of horizontal motion at the boundary between the North American and Pacific plates. Modern techniques of geologic dating and expanded research on earthquake hazards have greatly improved our knowledge of the San Andreas fault system. Much of this new knowledge has been gained since 1965, and that part which concerns crustal deformation during the past 2 m.y. is briefly summarized here.
Studies of pear-shaped nuclei using accelerated radioactive beams.
Gaffney, L P; Butler, P A; Scheck, M; Hayes, A B; Wenander, F; Albers, M; Bastin, B; Bauer, C; Blazhev, A; Bönig, S; Bree, N; Cederkäll, J; Chupp, T; Cline, D; Cocolios, T E; Davinson, T; De Witte, H; Diriken, J; Grahn, T; Herzan, A; Huyse, M; Jenkins, D G; Joss, D T; Kesteloot, N; Konki, J; Kowalczyk, M; Kröll, 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
2013-05-01
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 (220)Rn 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 studies of atomic electric-dipole moments that might reveal extensions to the standard model. PMID:23657348
HRIBF studies of r-process nuclei and first results with the new SuperORRUBA detector
NASA Astrophysics Data System (ADS)
Bardayan, D. W.; Ahn, S.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Cizewski, J. A.; Hardy, S.; Howard, M. E.; Jones, K. L.; Kozub, R. L.; O'Malley, P. D.; Manning, B.; Matoš, M.; Nesaraja, C. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Ratkiewicz, A.; Schmitt, K. T.; Smith, M. S.; Spassova, I.; Strauss, S.
2013-10-01
The astrophysical rapid neutron-capture process (r-process) is believed to have produced approximately half of the nuclear species more massive than Fe. Unfortunately, almost nothing is known about the structure of the majority of the extremely neutron-rich nuclei involved in the reaction flow. At exotic beam facilities such as the Holifield Radioactive Ion Beam Facility (HRIBF), measurements with accelerated beams of fission fragments have provided some of the first spectroscopic information on many r-process nuclei. The new SuperORRUBA (Oak Ridge Rutgers University Barrel Array) detector has been constructed at the HRIBF to study such nuclei, and first results are presented.
Fission Products Evaluation for the Selected Nuclei
Lee, Y.D.; Chang, J.H.
2005-05-24
The neutron cross sections of 19 selected high-priority nuclei were evaluated in the fast energy region. The calculation was compared with the CSISRS experimental data and the ENDF files. Evaluation procedures included an optical-model parameter search, followed by complete nuclear reaction model calculations with parameters validated against experimental data. A spherical and deformed optical model, MSC and MSD, pre-equilibrium exiton, and Hauser-Feshbach with a width fluctuation were used in the EMPIRE code. A considerable improvement was achieved for most of the nuclei cases. The results were merged with the resonance parameters (adopted in ENDF/B-VI.8). The final files were submitted to ENDF/B-VII for review.
Ghatan, Andrew C; Hanel, Douglas P
2013-06-01
Madelung deformity is a rare congenital anomaly of the wrist caused by asymmetric growth at the distal radial physis secondary to a partial ulnar-sided arrest. The deformity is characterized by ulnar and palmar curvature of the distal radius, positive ulnar variance, and proximal subsidence of the lunate. It more commonly occurs in females than males and typically affects both wrists. The deformity can occur in isolation or as part of a genetic syndrome. The pattern of inheritance varies, with some cases following a pseudoautosomal pattern and many others lacking a clear family history. Nonsurgical management is typically advocated in asymptomatic patients. Few studies exist on the natural history of the condition; however, extensor tendon ruptures have been reported in severe and chronic cases. Stiffness, pain, and patient concerns regarding wrist cosmesis have been cited as indications for surgery. Various techniques for surgical management of Madelung deformity have been described, but clear evidence to support the use of any single approach is lacking. PMID:23728962
Interaction of eta mesons with nuclei.
Kelkar, N G; Khemchandani, K P; Upadhyay, N J; Jain, B K
2013-06-01
Back in the mid-1980s, a new branch of investigation related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta-meson producing reactions. The vast literature of experimental as well as theoretical works that studied various aspects of eta-producing reactions such as the π(+)n → ηp, pd → (3)Heη, p (6)Li → (7)Be η and γ (3)He → η X, to name a few, had but one objective in mind: to understand the eta-nucleon (ηN) and hence the η-nucleus interaction which could explain the production data and confirm the existence of some η-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the ηN and hence the η-nucleus interaction. Therefore, this review is an attempt to bind together the findings in these works and draw some global and specific conclusions which can be useful for future explorations.The ηN scattering length (which represents the strength of the η-nucleon interaction) using different theoretical models and analyzing the data on η production in pion, photon and proton induced reactions was found to be spread out in a wide range, namely, 0.18 ≤ Re aηN ≤ 1.03 fm and 0.16 ≤ Rm aηN ≤ 0.49 fm. Theoretical searches of heavy η-mesic nuclei based on η-nucleus optical potentials and lighter ones based on Faddeev type few-body approaches predict the existence of several quasibound and resonant states. Although some hints of η-mesic states such as (3)(η)He and (25)(η)Mg do exist from previous experiments, the promise of clearer signals for the existence of η-mesic nuclei lies in the experiments to be performed at the J-PARC, MAMI and COSY facilities in the near future. This review is aimed at giving an overall status
Interaction of eta mesons with nuclei
NASA Astrophysics Data System (ADS)
Kelkar, N. G.; Khemchandani, K. P.; Upadhyay, N. J.; Jain, B. K.
2013-06-01
Back in the mid-1980s, a new branch of investigation related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta-meson producing reactions. The vast literature of experimental as well as theoretical works that studied various aspects of eta-producing reactions such as the π+n → ηp, pd → 3Heη, p 6Li → 7Be η and γ 3He → η X, to name a few, had but one objective in mind: to understand the eta-nucleon (ηN) and hence the η-nucleus interaction which could explain the production data and confirm the existence of some η-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the ηN and hence the η-nucleus interaction. Therefore, this review is an attempt to bind together the findings in these works and draw some global and specific conclusions which can be useful for future explorations. The ηN scattering length (which represents the strength of the η-nucleon interaction) using different theoretical models and analyzing the data on η production in pion, photon and proton induced reactions was found to be spread out in a wide range, namely, 0.18 ⩽ ℜe aηN ⩽ 1.03 fm and 0.16 ⩽ ℑm aηN ⩽ 0.49 fm. Theoretical searches of heavy η-mesic nuclei based on η-nucleus optical potentials and lighter ones based on Faddeev type few-body approaches predict the existence of several quasibound and resonant states. Although some hints of η-mesic states such as ^3_{\\eta} He and ^{25}_{\\eta} Mg do exist from previous experiments, the promise of clearer signals for the existence of η-mesic nuclei lies in the experiments to be performed at the J-PARC, MAMI and COSY facilities in the near future. This review is aimed at giving an overall
Exotic quarks in Twin Higgs models
Cheng, Hsin -Chia; Jung, Sunghoon; Salvioni, Ennio; Tsai, Yuhsin
2016-03-14
The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ~ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of themore » model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. As a result, depending on the details of the twin sector, the exotic quarks may be probed up to ~ 2.5 TeV at the LHC and beyond 10 TeV at a future 100 TeV collider, providing a strong test of this class of ultraviolet completions.« less
Exotic quarks in Twin Higgs models
NASA Astrophysics Data System (ADS)
Cheng, Hsin-Chia; Jung, Sunghoon; Salvioni, Ennio; Tsai, Yuhsin
2016-03-01
The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ˜ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of the model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. Depending on the details of the twin sector, the exotic quarks may be probed up to ˜ 2.5TeV at the LHC and beyond 10TeV at a future 100TeV collider, providing a strong test of this class of ultraviolet completions.
Discovering uncolored naturalness in exotic Higgs decays
NASA Astrophysics Data System (ADS)
Curtin, David; Verhaaren, Christopher B.
2015-12-01
Solutions to the hierarchy problem usually require top partners. In standard SUSY or composite Higgs theories, the partners carry SM color and are becoming increasingly constrained by LHC searches. However, theories like Folded SUSY (FS), Twin Higgs (TH) and Quirky Little Higgs (QLH) introduce uncolored top partners, which can be SM singlets or carry electroweak charge. Their small production cross section left doubt as to whether the LHC can effectively probe such scenarios. Typically, these partners are charged under their own mirror color gauge group. In FS and QLH, the absence of light mirror matter allows glueballs to form at the bottom of the mirror spectrum. This is also the case in some TH realizations. The Higgs can decay to these mirror glueballs, with the glueballs decaying into SM particles with potentially observable lifetimes. We undertake the first detailed study of this glueball signature and quantitatively demonstrate the discovery potential of uncolored naturalness via exotic Higgs decays at the LHC and a potential future 100TeV collider. Our findings indicate that mirror glueballs are the smoking gun signature of natural FS and QLH type theories, in analogy to tree-level Higgs coupling shifts for the TH. We show that glueball masses in the ˜ 10-60 GeV mass range are theoretically preferred. Careful treatment of lifetime, mirror-hadronization and non-perturbative uncertainties is required to perform meaningful collider studies. We outline several new search strategies for exotic Higgs decays of the form h → XX → 4 f at the LHC, with X having lifetimes in the 10 μm to km range. We find that FS stops can be probed with masses up to 600 (1100) GeV at the LHC with 300 (3000) fb-1 of data, and TH top partners could be accessible with masses up to 900 (1500) GeV. This makes exotic Higgs decays the prime discovery channel for uncolored naturalness at the LHC.
Big brake singularity is accommodated as an exotic quintessence field
NASA Astrophysics Data System (ADS)
Chimento, Luis P.; Richarte, Martín G.
2016-02-01
We describe a big brake singularity in terms of a modified Chaplygin gas equation of state p =(γm-1 )ρ +α γmρ-n, accommodate this late-time event as an exotic quintessence model obtained from an energy-momentum tensor, and focus on the cosmological behavior of the exotic field, its kinetic energy, and the potential energy. At the background level the exotic field does not blow up, whereas its kinetic energy and potential both grow without limit near the future singularity. We evaluate the classical stability of this background solution by examining the scalar perturbations of the metric along with the inclusion of entropy perturbation in the perturbed pressure. Within the Newtonian gauge, the gravitational field approaches a constant near the singularity plus additional regular terms. When the perturbed exotic field is associated with α >0 the perturbed pressure and contrast density both diverge, whereas the perturbed exotic field and the divergence of the exotic field's velocity go to zero exponentially. When the perturbed exotic field is associated with α <0 the contrast density always blows up, but the perturbed pressure can remain bounded. In addition, the perturbed exotic field and the divergence of the exotic field's velocity vanish near the big brake singularity. We also briefly look at the behavior of the intrinsic entropy perturbation near the singular event.
High spin spectroscopy for A approx 160 nuclei
Yu, C.-H. Tennessee Univ., Knoxville, TN . Dept. of Physics and Astronomy); Gascon, J.; Garrett, J.D.; Hagemann, G.B. )
1989-01-01
Experimental routhians, alignments, band crossing frequencies, and the B(M1)/B(E2) ratios of the N = 90 isotopes and several light Lu (N = 90--96) isotopes are summarized and discussed in terms of shape changes. These systematic analyses show a neutron and proton number dependent deformations (both quadruple and {gamma} deformations) for these light rare earth nuclei. The stability of the nuclear deformation with respect to {beta} and {gamma} is also found to be particle number dependent. Such particle number dependent shapes can be attributed to the different locations of the proton and neutron Fermi levels in the Nilsson diagrams. Configurations dependent shapes are discussed specially concerned the deformation difference between the proton h{sub 9/2}1/2{sup -}(541) and the high-K h{sub 11/2} configurations. The observed large neutron band crossing frequencies in the h{sub 9/2}1/2{sup -}(541) configuration support the predicted large deformation of this configuration but can be reproduced by the cranked shell model calculation according to the predicted deformations. Lifetime measurement for {sup 157}Ho, one of the nuclei that show a large {h bar}{omega}{sup c} in the 1/2{sup -}(541) band, indicates that deformation difference can only account for 20% of such shift in {h bar}{omega}{sub c}. 55 refs., 12 figs.
Global analysis of fermion mixing with exotics
NASA Technical Reports Server (NTRS)
Nardi, Enrico; Roulet, Esteban; Tommasini, Daniele
1991-01-01
The limits are analyzed on deviation of the lepton and quark weak-couplings from their standard model values in a general class of models where the known fermions are allowed to mix with new heavy particles with exotic SU(2) x U(1) quantum number assignments (left-handed singlets or right-handed doublets). These mixings appear in many extensions of the electroweak theory such as models with mirror fermions, E(sub 6) models, etc. The results update previous analyses and improve considerably the existing bounds.
Rare and exotic processes at CDF
Culbertson, Ray; /Fermilab
2010-01-01
We report recent results in CDF searches for rare and exotic processes. In a signature-based search, we examine the diphoton dataset for additional energetic objects. In a second signature-based search, we search for anomalous production of a photon, a b-tagged jet, and missing E{sub T}. Finally, we search for a Fermiophobic Higgs in the two-photon decay mode, and conclude this Higgs must have mass greater than 106 GeV/c{sup 2}, at 95% confidence level.
Technology Transfer Automated Retrieval System (TEKTRAN)
The pheromone lure for the exotic species Spodoptera exempta was successful at attracting two native species, S. latifascia and S. albula. Trapping was conducted in north-central Florida and in southern Texas. Large numbers of both native species were collected throughout the season....
Casten, R. F.
2007-10-26
A synoptic view of the evolution of structure with Z and N in nuclei is beginning to emerge from the confiuence of new experimental results on phase transitional behavior, newly proposed many-body symmetries for critical point nuclei, a new generation of solvable collective models, powerful approaches to viewing the systematics of nuclear properties based on simple models of residual interactions, and advances in microscopic calculations of medium mass and heavy nuclei. A recent compilation of nuclear masses has contributed by permitting empirical extractions of new p-n interaction strengths of the last protons with the last neutrons in many nuclei across the nuclear chart. A number of these developments will be discussed with an eye to the opportunities and challenges they provide for the future, especially in the era of next-generation exotic beam facihties throughout the world.
Isospin-symmetry-breaking effects in A∼70 nuclei within beyond-mean-field approach
Petrovici, A.; Andrei, O.
2015-02-24
Particular isospin-symmetry-breaking probes including Coulomb energy differences (CED), mirror energy differences (MED), and triplet energy differences (TED) manifest anomalies in the A∼70 isovector triplets of nuclei. The structure of proton-rich nuclei in the A∼70 mass region suggests shape coexistence and competition between pairing correlations in different channels. Recent results concerning the interplay between isospin-mixing and shape-coexistence effects on exotic phenomena in A∼70 nuclei obtained within the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction in a relatively large model space are presented. Excited Vampir predictions concerning the Gamow-Teller β decay to the odd-odd N=Z {sup 66}As and {sup 70}Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.
Search for Hyperdeformation in Light Xe Nuclei
NASA Astrophysics Data System (ADS)
Nyako, B. M.; Papp, F.; Gal, J.; Molnar, J.; Timar, J.; Algora, A.; Dombradi, Zs.; Kalinka, G.; Zolnai, L.; Juhasz, K.; Singh, A. K.; Huebel, H.; Al-Khatib, A.; Bringel, P.; Buerger, A.; Neusser, A.; Schoenwasser, G.; Herskind, B.; Hagemann, G. B.; Hansen, C. R.; Sletten, G.; Scheurer, J. N.; Hannachi, F.; Kmiecik, M.; Maj, A.; Styczen, J.; Zuber, K.; Hauschild, K.; Korichi, A.; Lopez-Martens, A.; Roccaz, J.; Siem, S.; Bednarczyk, P.; Byrski, Th.; Curien, D.; Dorvaux, O.; Duchene, G.; Gall, B.; Khalfallah, F.; Piqueras, I.; Robin, J.; Patel, S. B.; Evans, A. O.; Rainovski, G.; Airoldi, A.; Benzoni, G.; Bracco, A.; Camera, F.; Million, B.; Mason, P.; Paleni, A.; Sacchi, R.; Wieland, O.; La Rana, G.; Moro, R.; Petrache, C. M.; Petrache, D.; de Angelis, G.; Fallon, P.; Lee, I.-Y.; Lisle, J. C.; Cederwall, B.; Lagergren, K.; Lieder, R. M.; Podsvirova, E.; Gast, W.; Jaeger, H.; Redon, N.; Goergen, A.
2005-04-01
The ultimate search for hyperdeformation (HD) at high spins with the EUROBALL spectrometer was performed for 126Ba as a hyper long (HLHD) experiment. The DIAMANT ancillary detector was used to tag γ -rays in coincidence with the emitted light charged particles. Using γ -energy correlation methods, the particle--xn-γ data have been analysed to search for hyperdeformed structures in the corresponding residual nuclei. Data in coincidence with one α particle indicate the presence of normal deformed collective bands up to very high spins and the possible occurrence of HD-like ridge structures in 122Xe.
Rotational spacings in superdeformed bands of nuclei
Chasman, R.R.; Farhan, A.
1995-08-01
An unexpected result of the experimental investigation of superdeformed rotational bands is the observation of near-identical dynamic moments of inertia in different nuclei. This phenomenon was also noted in normally deformed rotational bands. A priori, the BCS method is suspect at I = 0 for the treatment of superdeformed nuclear shapes because the single-particle level density near the nuclear surface is small. If it were large, there would be no superdeformed minimum. At high spin, pairing correlations are further weakened, and the BCS method becomes even worse.
NASA Technical Reports Server (NTRS)
Malik, F. Bary
1993-01-01
The investigation indicates that nuclei with excitation energy of a few hundred MeV to BeV are more likely to radiate hot nuclear clusters than neutrons. These daughter clusters could, furthermore, de-excite emitting other hot nuclei, and the chain continues until these nuclei cool off sufficiently to evaporate primarily neutrons. A few GeV excited nuclei could radiate elementary particles preferentially over neutrons. Impact of space radiation with materials (for example, spacecraft) produces highly excited nuclei which cool down emitting electromagnetic and particle radiations. At a few MeV excitation energy, neutron emission becomes more dominant than gamma-ray emission and one often attributes the cooling to take place by successive neutron decay. However, a recent experiment studying the cooling process of 396 MeV excited Hg-190 casts some doubt on this thinking, and the purpose of this investigation is to explore the possibility of other types of nuclear emission which might out-compete with neutron evaporation.
Dudek, J.; Dubray, N.; Pangon, V.; Dobaczewski, J.; Olbratowski, P.; Schunck, N.
2006-08-18
Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetrahedral T{sub d} and/or octahedral O{sub h} symmetries sometimes at only a few hundreds of keV above the ground states in some rare earth nuclei around {sup 156}Gd and {sup 160}Yb. The underlying single-particle spectra manifest exotic fourfold rather than Kramers's twofold degeneracies. The associated shell gaps are very strong, leading to a new form of shape coexistence in many rare earth nuclei. We present possible experimental evidence of the new symmetries based on the published experimental results--although an unambiguous confirmation will require dedicated experiments.
Exotic modes of excitation and weak interaction rates at finite temperature
Paar, N.
2011-10-28
The interplay of isospin asymmetry and finite temperature in nuclei plays an important role on properties of nuclear excitations and weak interaction rates in stellar environment. Recently a fully self-consistent microscopic framework, based on Hartree-Fock plus random phase approximation using Skyrme functionals, has been introduced for description of excitations and weak-interaction cross sections at finite temperature. Another self-consistent framework involving nuclei at finite temperature has also been developed within relativistic mean field theory using effective Lagrangians with density dependent meson-nucleon vertex functions. Nuclear excitations are studied using finite temperature random phase approximation for the range of temperatures T = 0-2 MeV, as well as in nuclei far from stability. In the focus of research are the structure properties of exotic modes of excitation (e.g. pygmy dipole resonances) and charge-exchange modes (e.g. Gamow-Teller resonances and forbidden transitions). It is shown that finite temperature effects include novel low-energy multipole excitations and modifications of the Gamow-Teller transition spectra. Using a representative set of Skyrme functionals, as well as covariant energy density functional with DD-ME2 parameterization, both theory frameworks have been applied in calculations of electron-capture cross sections relevant in the stage of supernova precollapse.
Near-barrier Fusion Induced by Stable Weakly Bound and Exotic Halo Light Nuclei
Beck, C.; Zafra, A. Sanchez I.; Diaz-Torres, A.; Thompson, I. J.; Keeley, N.
2006-08-14
The effect of breakup is investigated for the medium weight 6Li+59Co system in the vicinity of the Coulomb barrier. The strong coupling of breakup/transfer channels to fusion is discussed within a comparison of predictions of the Continuum Discretized Coupled-Channels model which is also applied to 6He+59Co a reaction induced by the borromean halo nucleus 6He.
High-Resolution Experiments with Exotic Nuclei Created and Separated in Flight with the Frs
NASA Astrophysics Data System (ADS)
Geissel, H.; Dickel, T.; Franczak, B.; Haettner, E.; Knöbel, R.; Litvinov, Yu. A.; Münzenberg, G.; Plaβ, W. R.; Purushothaman, S.; Scheidenberge, C.; Weick, H.; Winfield, J. S.; Winkler, M.; Iwasa, N.; Patyk, Z.; Sun, B.; Yavor, M.
2015-06-01
High-resolution spectrometer experiments with energetic incident ion beams characterized by a large phase space represent a great challenge for in-flight rare-isotope facilities. Projectile fragments and fission products separated in flight have an inevitable large angular and momentum spread due to their stochastic creation processes and the atomic interactions in the production target, degrader and detector materials. Solutions are to use dedicated ion-optical systems like energy-loss spectrometers and isochronous systems, or methods which reduce the incident phase space by cooling and energy bunching methods. Recent experiments with the fragment separator FRS have demonstrated the success of these efforts and methods.
Target dependence in the study of collective modes in stable and exotic Ni nuclei
NASA Astrophysics Data System (ADS)
Le Bleis, T.; Rossi, D.; Klimkiewicz, A.; Adrich, P.; Boretzky, K.; Aksouh, F.; Alvarez-Pol, H.; Aumann, T.; Benlliure, J.; Boehmer, M.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Datta Pramanik, U.; Emling, H.; Ershova, O.; Fernandez-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Johansson, H.; Junghans, A. R.; Kiselev, O.; Kratz, J. V.; Kurz, N.; Labiche, M.; Lemmon, R.; Litvinov, Y.; Mahata, K.; Maierbeck, P.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.
2010-01-01
The appearance of the pygmy-dipole-resonance is a recently observed phenomenon that can be related to neutron-matter properties. Its study can be a tool to determine the nuclear symmetry-energy parameters and thus can contribute constraining neutron star models. We present the (γ,n) cross sections for different Ni isotopes obtained from a measurement in inverse kinematics at about 500 MeV/u in the LAND reaction setup at GSI. The question of the disentanglement of the Coulomb and nuclear contributions is addressed.
Studies of exotic nuclei: state-of-the-art experimental tools and techniques
NASA Astrophysics Data System (ADS)
Paschalis, Stefanos
2015-04-01
As new radioactive-ion beam facilities are coming online there is an even growing need for advanced experimental apparatuses that offer unprecedented resolution and efficiency and can fully exploit the physics opportunities that open up in this new for the nuclear physics community era. In this contribution state-of-the-art equipment and techniques for nuclear physics experiments are presented.
The scission point configuration of fissioning nuclei
NASA Astrophysics Data System (ADS)
Ivanyuk, Fedir
2016-06-01
We define the optimal shape which fissioning nuclei attain just before the scission and calculate the deformation energy as function of the mass asymmetry at the scission point. The calculated deformation energy is used in quasi-static approximation for the estimation of mass distribution, total kinetic and excitation energy of fission fragments, and the total number of prompt neutrons. The calculated results reproduce rather well the experimental data on the position of the peaks in the mass distribution of fission fragments, the total kinetic and excitation energy of fission fragments. The calculated value of neutron multiplicity is somewhat larger than experimental results. The saw-tooth structure of neutron multiplicity is qualitatively reproduced.
Quaglioni, S; Navratil, P; Roth, R
2009-12-15
The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear scattering and reactions, which require the solution of the many-body quantum-mechanical problem in the continuum, represent an extraordinary theoretical as well as computational challenge for ab initio approaches.We present a new ab initio many-body approach which derives from the combination of the ab initio no-core shell model with the resonating-group method [4]. By complementing a microscopic cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, this approach is capable of describing simultaneously both bound and scattering states in light nuclei. We will discuss applications to neutron and proton scattering on sand light p-shell nuclei using realistic nucleon-nucleon potentials, and outline the progress toward the treatment of more complex reactions.
Broglia, R.A.
1986-01-01
The dipole giant resonance is reviewed, as it is the only vibration which has been experimentally identified in the decay of hot nuclei. The mechanism of exciting the resonance and the mode of the resonance are described. The methods used to calculate the vibrations from the shell model are discussed, including the Hartree-Fock approximation and random phase approximation. Nuclei formed by compound nuclear reactions, which possess high excitation energy and angular momentum, are considered. It is argued that the stability of the dipole may be used to advantage in the study of other properties of nuclei at high excitation. It is also considered possible that the discussion of the dipole giant resonance may be extended to the gamma decay of the isovector quadrupole vibration. 26 refs., 18 figs. (LEW)
Evolution of collectivity in exotic isotopes
NASA Astrophysics Data System (ADS)
Zhu, Shaofei
2015-04-01
Neutron-rich nuclei have been the subject of much recent investigations. From the recent studies, the weakening of the N=40 shell gap is ascribed to the strong interaction between nucleons in the πpf and the νg9/2 and νd5/2 orbitals, which induces energy shifts of the single-particle states, thereby leading to an increased collectivity in neutron-rich nuclei beyond and below the 68 Ni40 core. Studies in this context of selected neutron-rich nuclei will be conducted extensively at ATLAS with Gammasphere or GRETINA using reactions well above the Coulomb barrier. A number such experiments have demonstrated that the yrast states of hard-to-reach neutron-rich nuclei can be populated allowing experimental access to high-spin structures in regions inaccessible with conventional heavy-ion induced, fusion-evaporation reactions. This material is based on work supported by the US Department of Energy (DOE), Office of Science, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
Alpha decay properties of superheavy nuclei Z = 126
NASA Astrophysics Data System (ADS)
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.
Spin-dependent modes in nuclei and nuclear forces
NASA Astrophysics Data System (ADS)
Suzuki, Toshio; Otsuka, Takaharu; Honma, Michio
2012-10-01
Spin-dependent modes in nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain spin properties of both stable and exotic nuclei. Gamow-Teller (GT) strengths in Ni isotopes, especially in 56Ni, are found to be well described by pf-shell Hamiltonian GXPF1J, which leads to a remarkable improvement in the evaluation of electron capture rates in stellar environmnets. GT strength in 40Ar obtained with VMU (monopole-based universal interaction) is found to be consistent with the experimental strength, and neutrino capture reaction cross sections for solar neutrinos from 8B are found to be enhanced compared with previous calculations. The repulsive monopole corrections to the microscopic two-body interactions in isospin T=1 channel are important for the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by δ excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies of exotic calcium isotopes as well as on the closed-shell nature of 48Ca and M1 transition in 48Ca are demonstrated.
Giant dipole resonance in hot and rotating nuclei
NASA Astrophysics Data System (ADS)
Banerjee, Sudhee R.
2013-04-01
The study of Giant Dipole Resonance (GDR) even after more than 60 years of its discovery, still remains an intriguing and a very relevant topic of research particularly in the case of hot and fast rotating nuclei. Many new facets of this giant collective mode of vibration are being brought to light recently owing to the new age powerful detection systems. Particularly for the nuclei with large asymmetries in its neutron and protons the study of its GDR decay modes opened up very interesting research prospects worldwide. Even with low energy light-ion and heavy-ion accelerated beams and employing the powerful large volume high energy photon spectrometer LAMBDA at VECC a number of very interesting experimental observations have been made recently which radically changes the present understanding of GDR vibrations in moderately hot nuclei in general. The availability of higher energy heavy-ion beams from the near ready superconducting cyclotron at VECC will open up many more interesting and challenging research prospects with the LAMBDA spectrometer. Exciting challenges and opportunities are also on offer for studying the properties and dynamics of hot exotic nuclei with stable and RI beams through high energy gamma decays from giant resonances. A few of the very interesting results obtained recently at VECC with the LAMBDA spectrometer, further research possibilities and several other powerful detector facilities will be discussed during the conference.
Mosel, Ulrich
2004-08-30
Changes of hadronic properties in dense nuclear matter as predicted by theory have usually been investigated by means of relativistic heavy-ion reactions. In this talk I show that observable consequences of such changes can also be seen in more elementary reactions on nuclei. Particular emphasis is put on a discussion of photonuclear reactions; examples are the dilepton production at {approx_equal} 1 GeV and the hadron production in nuclei at 10-20 GeV photon energies. The observable effects are expected to be as large as in relativistic heavy-ion collisions and can be more directly related to the underlying hadronic changes.
Education and Feminist Aesthetics: Gauguin and the Exotic
ERIC Educational Resources Information Center
Duran, Jane
2009-01-01
Throughout this article, the author argued that the attraction of the "exotic" for Gauguin was largely revealed by his response to the women of various locales and that two notions--that of the "feminine" and the "foreign" or exotic--became intertwined for him. She relied both upon the commentary of Britt Salvesen with respect to Gauguin's obvious…
Resources for Teaching and Learning about Exotic Species. ERIC Digest.
ERIC Educational Resources Information Center
Lee, Hyonyong; Fortner, Rosanne W.
Exotic species are organisms transported by humans, wildlife, wind, and water into regions where they did not historically exist. This ERIC Digest describes available materials and resources for teaching and learning about these exotic species. Sixteen Internet sources are provided along with six videotape resources. The digest also provides…
Fire management to prevent and control exotic annual grass invasion
Technology Transfer Automated Retrieval System (TEKTRAN)
Management of fire is often a critical component of exotic plant prevention and control. It is especially important in the sagebrush ecosystem where exotic annual grasses are spreading rapidly. Historically, in the sagebrush ecosystem, infrequent fires shifted vegetation dominance from sagebrush t...
Fire management to prevent and control exotic annual grass invasion
Technology Transfer Automated Retrieval System (TEKTRAN)
Management of fire is often a critical component of exotic plant prevention and control. It is especially important in the sagebrush ecosystem where exotic annual grasses are spreading rapidly. Historically, in the sagebrush ecosystem, infrequent fires shifted vegetation dominance from sagebrush to ...
Interplay between one-particle and collective degrees of freedom in nuclei
NASA Astrophysics Data System (ADS)
Hamamoto, Ikuko
2016-02-01
Some developments of nuclear-structure physics uniquely related to Copenhagen School are sketched based on theoretical considerations versus experimental findings and one-particle versus collective aspects. Based on my personal overview I pick up the following topics; (1) Study of vibration in terms of particle-vibration coupling; (2) one-particle motion in deformed and rotating potentials, and yrast spectroscopy in high-spin physics; (3) triaxial shape in nuclei: wobbling motion and chiral bands; (4) nuclear structure of drip line nuclei: in particular, shell-structure (or magic numbers) change and spherical or deformed halo phenomena; (5) shell structure in oblate deformation.
Alternating-parity collective states of yrast and nonyrast bands in lanthanide and actinide nuclei
Nadirbekov, M. S. Yuldasheva, G. A.; Denisov, V. Yu.
2015-03-15
Excited collective states of even-even nuclei featuring quadrupole and octupole deformations are studied within a nonadiabatic collective model with a Gaussian potential energy. Rotational states of the yrast band and vibrational-rotational states of nonyrast bands are considered in detail. The energies of alternating-parity excited states of the yrast band in the {sup 164}Er, {sup 220}Ra, and {sup 224}Th nuclei; the yrast and first nonyrast bands in the {sup 154}Sm and {sup 160}Gd nuclei; and the yrast, first nonyrast, and second nonyrast bands in the {sup 224}Ra and {sup 240}Pu nuclei are described well on the basis of the proposed model.
New regions of nuclear deformation
Lister, C.J.; Gelletly, W.; Varley, B.J.; Price, H.G.; Olness, J.W.
1983-01-01
It has long been expected from general theoretical considerations that nuclei with Z and N far removed from major shell closures should exhibit considerable collectivity and maybe deformed in their groundstates. A number of calculations have recently attempted to quantify these expectations through detailed predictions of nuclear shapes across the periodic table. In this contribution we review predictions and experimental data for the regions with Z,N = (40,40), (40,64) and (64,64) which are all off the valley of stability. Emphasis is placed on the experimental techniques and data obtained from the first of these regions where the prediction of extremely large prolate deformation has been experimentally verified.
Blankenbecler, R.
1981-01-01
A brief review is given of selected topics involved in the relativistic quark structure of nuclei such as the infinite momentum variables, scaling variables, counting rules, forward-backward variables, thermodynamic-like limit, QCD effects, higher quark bags, confinement, and many unanswered questions.
Physics with Polarized Nuclei.
ERIC Educational Resources Information Center
Thompson, William J.; Clegg, Thomas B.
1979-01-01
Discusses recent advances in polarization techniques, specifically those dealing with polarization of atomic nuclei, and how polarized beams and targets are produced. These techniques have greatly increased the scope of possible studies, and provided the tools for testing fundamental symmetries and the spin dependence of nuclear forces. (GA)
Octupole collectivity in nuclei
NASA Astrophysics Data System (ADS)
Butler, P. A.
2016-07-01
The experimental and theoretical evidence for octupole collectivity in nuclei is reviewed. Recent theoretical advances, covering a wide spectrum from mean-field theory to algebraic and cluster approaches, are discussed. The status of experimental data on the behaviour of energy levels and electric dipole and electric octupole transition moments is reviewed. Finally, an outlook is given on future prospects for this field.
Systematic Study of Fission Barriers of Excited Superheavy Nuclei
Sheikh, J. A.; Nazarewicz, Witold; Pei, J. C.
2009-01-01
A systematic study of fission-barrier dependence on excitation energy has been performed using the self-consistent finite-temperature Hartree-Fock+BCS (FT-HF+BCS) formalism with the SkM* Skyrme energy density functional. The calculations have been carried out for even-even superheavy nuclei with Z ranging between 110 and 124. For an accurate description of fission pathways, the effects of triaxial and reflection asymmetric degrees of freedom have been fully incorporated. Our survey demonstrates that the dependence of isentropic fission barriers on excitation energy changes rapidly with particle number, pointing to the importance of shell effects even at large excitation energies characteristic of compound nuclei. The fastest decrease of fission barriers with excitation energy is predicted for deformed nuclei around N = 164 and spherical nuclei around N = 184 that are strongly stabilized by ground-state shell effects. For nuclei ^{240}Pu and ^{256}Fm, which exhibit asymmetric spontaneous fission, our calculations predict a transition to symmetric fission at high excitation energies due to the thermal quenching of static reflection asymmetric deformations.
Experiments with Exotic Spin-Oriented Nuclear Beams and Examples of Nuclear Moment Measurements
NASA Astrophysics Data System (ADS)
Balabanski, D. L.; Neyens, G.; Borremans, D.; Coulier, N.; Daugas, J. M.; Teughels, S.; Georgiev, G.; Lewitowicz, M.; de Oliveira Santos, F.; Penionzhkevich, Yu. E.
2002-04-01
An overview of a series of recent experiments aimed at the determination of the moments of exotic nuclei is presented. The spin-orientation: spin-alignment and spin-polarization of the nuclear ensemble, which is produced in fragmentation reactions, is of utmost importance for these studies. The discussion emphasizes on the open problems related to the production and the preservation of the orientation during the experiments. Pros and contras for experiments at both, intermediate and high energies are considered. Examples from nuclear moment measurements, which were performed using the LISE-III spectrometer at GANIL, are provided. The spin-alignment and the spin-polarization of the nuclear ensemble were studied by the β-LMR, β-NMR and TDPAD experimental techniques. The experimental results are discussed in the framework of the kinematical model of the fragmentation reaction.
Moretto, L.G.; Wozniak, G.J.
1988-11-01
The formation of hot compound nuclei in intermediate-energy heavy ion reactions is discussed. The statistical decay of such compound nuclei is responsible for the abundant emission of complex fragments and high energy gamma rays. 43 refs., 23 figs.
EXOTIC PARTICLE SEARCHES WITH STAR AT RHIC.
KANABA,S.
2004-03-15
We present preliminary results of the STAR experiment at RHIC on exotic particle searches in minimum bias Au + Au collisions at {radical} s{sub NN} = 200 GeV. We observe a narrow peak at 1734 {+-} 0.5 {+-} 5 MeV in the {lambda}K{sub s}{sup 0} invariant mass with width consistent with the experimental resolution of about 6 MeV within the errors. The statistical significance can be quantified between 3 and 6 {sigma} depending on cuts and methods. If this peak corresponds to a real particle state it would be a candidate for the N{sup 0} or the {Xi}{sup 0} I = 1/2 pentaquark states.
Electroweak baryogenesis from exotic electroweak symmetry breaking
NASA Astrophysics Data System (ADS)
Blinov, Nikita; Kozaczuk, Jonathan; Morrissey, David E.; Tamarit, Carlos
2015-08-01
We investigate scenarios in which electroweak baryogenesis can occur during an exotic stage of electroweak symmetry breaking in the early Universe. This transition is driven by the expectation value of a new electroweak scalar instead of the standard Higgs field. A later, second transition then takes the system to the usual electroweak minimum, dominated by the Higgs boson, while preserving the baryon asymmetry created in the first transition. We discuss the general requirements for such a two-stage electroweak transition to be suitable for electroweak baryogenesis and present a toy model that illustrates the necessary ingredients. We then apply these results to construct an explicit realization of this scenario within the inert two Higgs doublet model. Despite decoupling the Higgs from the symmetry-breaking transition required for electroweak baryogenesis, we find that this picture generically predicts new light states that are accessible experimentally.
Simplified models for exotic BSM searches
NASA Astrophysics Data System (ADS)
Heisig, Jan; Lessa, Andre; Quertenmont, Loic
2015-12-01
Simplified models are a successful way of interpreting current LHC searches for models beyond the standard model (BSM). So far simplified models have focused on topologies featuring a missing transverse energy (MET) signature. However, in some BSM theories other, more exotic, signatures occur. If a charged particle becomes long-lived on collider time scales — as it is the case in parts of the SUSY parameter space — it leads to a very distinct signature. We present an extension of the computer package SModelS which includes simplified models for heavy stable charged particles (HSCP). As a physical application we investigate the CMSSM stau co-annihilation strip containing long-lived staus, which presents a potential solution to the Lithium problem. Applying both MET and HSCP constraints we show that, for low values of tan β, all this region of parameter space either violates Dark Matter constraints or is excluded by LHC searches.
Probing Exotic Physics With Supernova Neutrinos
Kelso, Chris; Hooper, Dan
2010-09-01
Future galactic supernovae will provide an extremely long baseline for studying the properties and interactions of neutrinos. In this paper, we discuss the possibility of using such an event to constrain (or discover) the effects of exotic physics in scenarios that are not currently constrained and are not accessible with reactor or solar neutrino experiments. In particular, we focus on the cases of neutrino decay and quantum decoherence. We calculate the expected signal from a core-collapse supernova in both current and future water Cerenkov, scintillating, and liquid argon detectors, and find that such observations will be capable of distinguishing between many of these scenarios. Additionally, future detectors will be capable of making strong, model-independent conclusions by examining events associated with a galactic supernova's neutronization burst.
Exotic Photon Searches at CDF II
Lee, Eunsin; collaboration, for the CDF
2009-10-01
We present recent results of searches for exotic photons at CDF II. In the first signature-based search, we search for anomalous production of two photons with additional energetic objects. The results are consistent with the standard model expectations. In the second analysis, we present a signature-based search for anomalous production of events containing a photon, two jets, of which at least one is identified as originating from a b quark, and missing transverse energy. We find no indications of non-standard model phenomena. Finally, a search for a fermiophobic Higgs in the diphoton final state is presented. Since no evidence of a resonance in the diphoton mass spectrum is observed we exclude this Higgs boson with mass below 106 GeV/c{sup 2} at a 95% confidence level.
Probing exotic physics with cosmic neutrinos
Hooper, Dan; /Fermilab
2005-10-01
Traditionally, collider experiments have been the primary tool used in searching for particle physics beyond the Standard Model. In this talk, I will discuss alternative approaches for exploring exotic physics scenarios using high energy and ultra-high energy cosmic neutrinos. Such neutrinos can be used to study interactions at energies higher, and over baselines longer, than those accessible to colliders. In this way, neutrino astronomy can provide a window into fundamental physics which is highly complementary to collider techniques. I will discuss the role of neutrino astronomy in fundamental physics, considering the use of such techniques in studying several specific scenarios including low scale gravity models, Standard Model electroweak instanton induced interactions, decaying neutrinos and quantum decoherence.
The Exotic Exchange of Smoke Rings
NASA Astrophysics Data System (ADS)
Niemi, A. J.
Smoke rings are fascinating, to humans and animals alike.Experienced cigarette smokers blow them for entertainment while dolphins play with air-filled underwater rings that they know how to puff.~Smoke ring machines can be bought from science gadget shops and Lord Kelvin explains in a paper [Lord Kelvin, Proceedings of the Royal Society of Edinburgh, Vol. VI (1867), p. 94; reprinted in Philos. Mag. Vol. XXXIV (1867), p.~15] how one can be constructed from a cardboard box. Even Mount Etna [http://news.bbc.co.uk/1/hi/sci/tech/696953.stm] and our Sun [http://spacescience.com/headlines/y2000/ast03feb_1.htm] are known to be sources of huge smoke rings. But a smoke ring is not only fun to watch. It is also an organized structure with the ability to engage in complex acts, best exemplified by the leapfrogging motion of two smoke rings. Here we propose that the leapfrogging actually encodes very important Physics: It is a direct three dimensional generalization of the motion that in the two dimensional context is responsible for exotic exchange statistics which rules the properties of structures and materials such as quantum Hall systems and high-temperature superconductors. By employing very simple and universal concepts with roots in the hydrodynamical Euler equation, the universal law that describes the properties of fluids and gases, we argue that three dimensional exotic exchange statistics is commonplace. Our observations could have far reaching consequences in fluids and gases which are subject to the laws of quantum mechanics, from helium supefluids to Bose-Einstein condensed alkali gases and even metallic hydrogen in its liquid phases.
Modes of decay in neutron-rich nuclei
NASA Astrophysics Data System (ADS)
Kumar, B.; Biswal, S. K.; Singh, S. K.; Lahiri, C.; Patra, S. K.
2016-03-01
We calculate the ground, first intrinsic excited states and density distribution for neutron-rich thorium and uranium isotopes, within the framework of relativistic mean field (RMF) approach using axially deformed basis. The total nucleon densities are calculated, from which the cluster-structures inside the parent nuclei are determined. The possible modes of decay, like α-decay and β-decay are analyzed. We find the neutron-rich isotopes are stable against α-decay, however they are very much unstable against β-decay. The life time of these nuclei predicted to be tens of second against β-decay.
{alpha} decay of high-spin isomers in superheavy nuclei
Delion, D. S.; Liotta, R. J.; Wyss, R.
2007-10-15
Hindrance factors corresponding to {alpha} decay from two quasiparticle isomeric high K states are evaluated in superheavy nuclei. We found that the hindrance factors are very sensitive to the deformations and, therefore, they may constitute a powerful tool to extract spectroscopic information in these nuclei. The hindrance factors turn out to be very large, specially for nonaligned configurations. This indicates that if one of such states is reached the parent nucleus may become isomeric. It is also possible that {alpha} decay may not proceed through ground state to ground state chains but rather through excited states.
Octupole shaps in nuclei, and some rotational consequences thereof
Nazarewicz, W.; Olanders, P.; Ragnarsson, I.; Dudek, J.; Leander, G.A.
1984-01-01
During the last years a large number of experimental papers presenting spectroscopic evidence for collective dipole and octupole deformations have appeared. Many theoretical attempts have been made to explain the observed spectroscopic properties in terms of stable octupole deformations. The coupling by the octupole potential, being proportional to Y/sub 30/, is strongest for those subshells for which ..delta..1 = 3. Therefore the tendency towards octupole deformation occurs just beyond closed shells where the high-j intruder subshells (N,1,j) lie very close to the normal parity subshells (N-1,1-3,j-3), i.e. for the particle numbers 34 (g/sub 9/2/-p/sub 3/2/), 56 (h/sub 11/2/-d/sub 5/2/). 9C (i/sub 13/2/-f/sub 7/2/) and 134 (j/sub 15/2/-g/sub 9/2/). Empirically, it is specifically for the particle numbers listed above that negative parity states are observed at relatively low energies in doubly even nuclei. From the different combinations of octupole-driving particle numbers four regions of likely candidates for octupole deformed equilibrium shapes emerge, namely the neutron-deficient nuclei with Z approx. = 90, N approx. = 134 (light actinides) and Z approx. = 34, N approx. = 34 (A approx. = 70) and the neutron-rich nuclei with Z approx. = 56, N approx. = 90 (heavy Ba) and Z approx. = 34, N/sup 56/ (A approx. = 90). In our calculations we searched for octupole unstable nuclei in these four mass regions. The Strutinsky method with the deformed Woods-Saxon potential was employed. The macroscopic part consists of a finite-range liquid drop energy, where both the surface and Coulomb terms contain a diffuseness correction.
Energetic Nuclei, Superdensity and Biomedicine
ERIC Educational Resources Information Center
Baldin, A. M.
1977-01-01
High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…
Evolution of pre-collective nuclei: Structural signatures near the drip lines
Casten, R.F.; Zamfir, N.V. ||
1994-10-01
Recent studies have shown that the phenomenology of single-magic and near-magic nuclei has universal characteristics analogous to those of collective nuclei and that, moreover, this phenomenology attaches smoothly to that describing collective nuclei. This has led to a number of new signatures of structure as well as to a new, tripartite, classification of nuclear structure that embraces the gamut of structures from magic, through pre-collective, to fully collective and rotational nuclei. Aside from the natural appeal of simple global correlations of collective observables, these results have particular significance for soon-to-be accessible exotic nuclei near the drip lines since they rely on only the simplest-to-obtain data, in particular, the energies of just the first two excited states, E(4{sub 1}{sup +}) and E(2{sub 1}{sup +}), of even-even nuclei, and the B(E2:2{sub 1}{sup +}{yields}0{sub 1}{sup +}) value. Indeed, without the need for more extensive level schemes, these basic data alone can reveal information about the goodness of seniority, about the validity of pair-addition mode relationships of adjacent even-even nuclei, about underlying shell structure (validity of magic numbers) and even about the shell model potential itself (e.g., the strengths of the l{center_dot} and l{sup 2} terms).
NASA Astrophysics Data System (ADS)
Rice, T. Maurice; Sigrist, Manfred; Maeno, Yoshiteru
2009-05-01
Superconductors can usefully be divided into two classes, those that are well described by the classic Bardeen-Cooper-Schrieffer (BCS) theory and its extensions and those which require a different microscopic description. The BCS theory of superconductivity solved the long standing mystery of this spectacular phenomenon and described all superconductors that were known when it was formulated in the 1950s. The key ingredient is an attractive interaction generated by the exchange of phonons between electrons which overcomes a Coulomb repulsion weakened by screening, to give a net attractive force on the low energy scale. In this case the simplest s-wave pairing always maximises the energy gain. There were speculations a little later that other types of electron pairing could be possible, but it took a quarter of a century until the first signs of superconductors with different and exotic pairing appeared. In the intervening thirty years many superconductors with exotic pairing have been and continue to be discovered and the study of their superconductivity has grown into a major subfield of condensed matter physics today. The importance of these exotic superconductors with unconventional symmetry is that their pairing is of electronic origin. As a result they are freed from the restrictions of low transition temperatures that go along with the phonon driven conventional superconductors. However in two of the main classes of the exotic superconductors, namely heavy fermion and organic superconductors, the intrinsic energy scales are very small leading to low temperature scales. The third class contains the small number of superconducting transition metal compounds with exotic pairing symmetry. The most studied of these are the high-Tc cuprates, the newly discovered iron pnictides and strontium ruthenate which is closely related to superfluid 3He. Although the basic electronic structure of these materials is well understood, the origin of the pairing is more complex
Ecosystem engineers modulate exotic invasions in riparian plant communities
NASA Astrophysics Data System (ADS)
Corenblit, D.; Tabacchi, E.; Steiger, J.; Gonzales, E.; Planty-Tabacchi, A. M.
2012-04-01
The relationship between biodiversity and invasibility of exotic plant species within different environments and at different spatial scales is still being discussed amongst scientists. In this study, patterns of native and exotic plant species richness and cover were examined in relation with ecosystem engineer effects of pioneer vegetation within the active tract of the Mediterranean gravel bed river Tech, South France. The floristic composition was characterized according to two distinct vegetation types corresponding to two habitats with contrasted conditions: (i) open and exposed alluvial bars dominated by herbaceous communities and (ii) islands and river margins partly stabilized by ecosystem engineer plants, disconnected from annual hydrogeomorphic disturbances, and covered by woody vegetation. A significant positive correlation between exotic and native plant species richness and cover was observed for the herbaceous and the woody types, indicating that both native and exotic richness benefit from the prevailing environmental conditions. However, significant differences in native and exotic specific richness and cover were found between these two vegetation types. Higher values of total species richness and Shannon diversity of native and exotic species were attained within the herbaceous vegetation type compared to the woody type. These differences may be related to changes in local exposure to hydrogeomorphic disturbances driven by engineer plant species, and to vegetation succession. A lower exotic cover within the woody vegetation type compared to the herbaceous type suggested an increase of resistance to invasion by exotic species during the biogeomorphic succession. The engineer effects of woody vegetation resulted in a decrease of alpha (α) diversity at patch scale but, in parallel, caused an increase in gamma (γ) diversity at the scale of the studied river segment. Our study corroborates recent investigations that support the theory of biotic
NASA Technical Reports Server (NTRS)
Turco, R. P.; Toon, O. B.; Whitten, R. C.; Cicerone, R. J.
1982-01-01
Estimates are made showing that, as a consequence of rocket activity in the earth's upper atmosphere in the Shuttle era, average ice nuclei concentrations in the upper atmosphere could increase by a factor of two, and that an aluminum dust layer weighing up to 1000 tons might eventually form in the lower atmosphere. The concentrations of Space Shuttle ice nuclei (SSIN) in the upper troposphere and lower stratosphere were estimated by taking into account the composition of the particles, the extent of surface poisoning, and the size of the particles. Calculated stratospheric size distributions at 20 km with Space Shuttle particulate injection, calculated SSIN concentrations at 10 and 20 km altitude corresponding to different water vapor/ice supersaturations, and predicted SSIN concentrations in the lower stratosphere and upper troposphere are shown.
NASA Astrophysics Data System (ADS)
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.
Size-Invariant Detection of Cell Nuclei in Microscopy Images.
Ram, Sundaresh; Rodriguez, Jeffrey J
2016-07-01
Accurate detection of individual cell nuclei in microscopy images is an essential and fundamental task for many biological studies. In particular, multivariate fluorescence microscopy is used to observe different aspects of cells in cultures. Manual detection of individual cell nuclei by visual inspection is time consuming, and prone to induce subjective bias. This makes automatic detection of cell nuclei essential for large-scale, objective studies of cell cultures. Blur, clutter, bleed-through, imaging noise and touching and partially overlapping nuclei with varying sizes and shapes make automated detection of individual cell nuclei a challenging task using image analysis. In this paper we propose a new automated method for fast and robust detection of individual cell nuclei based on their radial symmetric nature in fluorescence in-situ hybridization (FISH) images obtained via confocal microscopy. The main contributions are two-fold. 1) This work presents a more accurate cell nucleus detection system using the fast radial symmetry transform (FRST). 2) The proposed cell nucleus detection system is robust against most occlusions and variations in size and moderate shape deformations. We evaluate the performance of the proposed algorithm using precision/recall rates, Fβ-score and root-mean-squared distance (RMSD) and show that our algorithm provides improved detection accuracy compared to existing algorithms. PMID:26886972
Revelation of Double Magicity in N = Z Nuclei in the RP-Process Region
Sharma, M. M.; Sharma, J. K.
2010-04-30
In rapid-proton capture (rp-process), N = Z nuclei above Ni are understood to act as waiting-point nuclei. The N = Z nuclei {sup 68}Se, {sup 72}Kr, {sup 76}Sr and {sup 80}Zr among others are known to give rise to a large-energy x-ray flux and peaks in abundances of these nuclei synthesized in the astrophysical rp-process. Investigating the experimental isotope shifts in Kr isotopes near the proton drip-line within the framework of the deformed Relativistic Hartree-Bogoliubov theory, we have discovered that N = Z rp-process nuclei {sup 68}Se, {sup 72}Kr, {sup 76}Sr and {sup 80}Zr exhibit large shell gap both at the proton and neutron numbers in the deformed space with the consequence that pairing correlations for protons and neutrons vanish. This lends a doubly magic character to these nuclei. A significant number of nuclei in this region are also shown to exhibit neutron magicity at N = 34, 36, 38, and 40 in the deformed space. A unique case of concomitance of the double magicity and the shape-coexistence is found for {sup 68}Se.
Chasman, R.R.
1996-12-31
In this contribution, the author mentions some features of pairing forces that are unique to nuclei and cover some areas of major interest in nuclear structure research, that involve pairing. At the level of most nuclear structure studies, nuclei are treated as consisting of two kinds of fermions (protons and neutrons) in a valence space with rather few levels. These features give rise to unique aspects of pairing forces in nuclei: (1) n-p pairing in T = 0 as well as the usual T = 1 pairing that is characteristic of like fermions; (2) a need to correct pairing calculations for the (1/N) effects that can typically be neglected in superconducting solids. An issue of current concern is the nature of the pairing interaction: several recent studies suggest a need for a density dependent form of the pairing interaction. There is a good deal of feedback between the questions of accurate calculations of pairing interactions and the form and magnitude of the pairing interaction. Finally, the authors discuss some many-body wave functions that are a generalization of the BCS wave function form, and apply them to a calculation of energy level spacings in superdeformed rotational bands.
Issues and Opportunities in Exotic Hadrons
NASA Astrophysics Data System (ADS)
Briceño, R. A.; Cohen, T. D.; Coito, S.; Dudek, J. J.; Eichten, E.; Fischer, C. S.; Fritsch, M.; Gradl, W.; Jackura, A.; Kornicer, M.; Krein, G.; Lebed, R. F.; Machado, F. A.; Mitchell, R. E.; Morningstar, C. J.; Peardon, M.; Pennington, M. R.; Peters, K.; Richard, J. M.; Shen, C. P.; Shepherd, M. R.; Skwarnicki, T.; Swanson, E. S.; Szczepaniak, A. P.; Yuan, C. Z.
2016-04-01
The last few years have been witness to a proliferation of new results concerning heavy exotic hadrons. Experimentally, many new signals have been discovered that could be pointing towards the existence of tetraquarks, pentaquarks, and other exotic configurations of quarks and gluons. Theoretically, advances in lattice field theory techniques place us at the cusp of understanding complex coupled-channel phenomena, modelling grows more sophisticated, and effective field theories are being applied to an ever greater range of situations. It is thus an opportune time to evaluate the status of the field. In the following, a series of high priority experimental and theoretical issues concerning heavy exotic hadrons is presented. Supported by U.S. Department of Energy (Cohen); the Institute of Modern Physics and Chinese Academy of Sciences under contract Y104160YQ0 and agreement No. 2015-BH-02 (Coito); the U.S. Department of Energy, for grant DE-AC05-06OR23177, under which Jefferson Science Associates, LLC, manages and operates Jefferson Laboratory and DE-SC0006765, Early Career award (Dudek); Fermilab, operated by the Fermi Research Alliance under contract number DEAC02-07CH11359 with the U.S. Department of Energy (Eichten); BMBF, under contract No. 06GI7121, and the DAAD under contract No. 56889822 and by the Helmholtz International Center for FAIR within the LOEWE program of the State of Hesse (Fischer); the German Research Foundation DFG under contract number Collaborative Research Centre CRC-1044 (Gradl); the Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq, Grant No. 305894/2009-9 and Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP, Grant No. 2013/01907-0 (Krein); U.S. National Science Foundation, under grants PHY-1068286 and PHY-1403891 (Lebed); the Brazilian National Council for Scientific and Technological Development under grant CNPq/CAPES-208188/2014-2 (Machado); U.S. Department of Energy under grant DE-FG02-05ER41374
Nuclear structure/nuclei far from stability
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
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.
Triaxiality and shape coexistence in the A ~ 30 island of inversion nuclei
NASA Astrophysics Data System (ADS)
Dong, GuoXiang; Wang, XiaoBao; Yu, ShaoYing
2015-11-01
Understanding the properties of nuclei inside "island of inversion" is still an interesting issue. Based on a simple Nilsson model with a new set of isospin-dependent parameters, and with non-axial deformations considered, we have performed three-dimensional potential-energy-surface calculations for Ne, Na, Mg and Al isotopes that are claimed to be in or nearby the A ~ 30 island of inversion. It is found that shape coexistence and triaxial deformation (or softness) exist in these nuclei. Large deformations are obtained by the improved Nilsson parameters, which explains the observed large electric quadrupole transition probabilities. The large deformations happening in 30Ne, 31Na, 32Mg and 33Al indicate the quenching of the spherical N = 20 neutron shell gap. The calculations of nuclear binding and two-neutron separation energies have been also improved with the isospin-dependent parameters and the inclusion of the non-axial deformation degree of freedom.
Collective modes in light nuclei from first principles.
Dytrych, T; Launey, K D; Draayer, J P; Maris, P; Vary, J P; Saule, E; Catalyurek, U; Sosonkina, M; Langr, D; Caprio, M A
2013-12-20
Results for ab initio no-core shell model calculations in a symmetry-adapted SU(3)-based coupling scheme demonstrate that collective modes in light nuclei emerge from first principles. The low-lying states of 6Li, 8Be, and 6He are shown to exhibit orderly patterns that favor spatial configurations with strong quadrupole deformation and complementary low intrinsic spin values, a picture that is consistent with the nuclear symplectic model. The results also suggest a pragmatic path forward to accommodate deformation-driven collective features in ab initio analyses when they dominate the nuclear landscape. PMID:24483740
Deformation properties of lead isotopes
NASA Astrophysics Data System (ADS)
Tolokonnikov, S. V.; Borzov, I. N.; Lutostansky, Yu. S.; Saperstein, E. E.
2016-01-01
The deformation properties of a long lead isotopic chain up to the neutron drip line are analyzed on the basis of the energy density functional (EDF) in the FaNDF0 Fayans form. The question of whether the ground state of neutron-deficient lead isotopes can have a stable deformation is studied in detail. The prediction of this deformation is contained in the results obtained on the basis of the HFB-17 and HFB-27 Skyrme EDF versions and reported on Internet. The present analysis reveals that this is at odds with experimental data on charge radii and magnetic moments of odd lead isotopes. The Fayans EDF version predicts a spherical ground state for all light lead isotopes, but some of them (for example, 180Pb and 184Pb) prove to be very soft—that is, close to the point of a phase transition to a deformed state. Also, the results obtained in our present study are compared with the predictions of some other Skyrme EDF versions, including SKM*, SLy4, SLy6, and UNE1. By and large, their predictions are closer to the results arising upon the application of the Fayans functional. For example, the SLy4 functional predicts, in just the same way as the FaNDF0 functional, a spherical shape for all nuclei of this region. The remaining three Skyrme EDF versions lead to a deformation of some light lead isotopes, but their number is substantially smaller than that in the case of the HFB-17 and HFB-27 functionals. Moreover, the respective deformation energy is substantially lower, which gives grounds to hope for the restoration of a spherical shape upon going beyond the mean-field approximation, which we use here. Also, the deformation properties of neutron-rich lead isotopes are studied up to the neutron drip line. Here, the results obtained with the FaNDF0 functional are compared with the predictions of the HFB-17, HFB-27, SKM*, and SLy4 Skyrme EDF versions. All of the EDF versions considered here predict the existence of a region where neutron-rich lead isotopes undergo
9 CFR 352.3 - Application by official exotic animal establishment for inspection services.
Code of Federal Regulations, 2011 CFR
2011-01-01
... PRODUCTS INSPECTION AND VOLUNTARY INSPECTION AND CERTIFICATION EXOTIC ANIMALS AND HORSES; VOLUNTARY INSPECTION Exotic Animals § 352.3 Application by official exotic animal establishment for inspection services... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Application by official exotic...
9 CFR 352.3 - Application by official exotic animal establishment for inspection services.
Code of Federal Regulations, 2010 CFR
2010-01-01
... PRODUCTS INSPECTION AND VOLUNTARY INSPECTION AND CERTIFICATION EXOTIC ANIMALS AND HORSES; VOLUNTARY INSPECTION Exotic Animals § 352.3 Application by official exotic animal establishment for inspection services... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Application by official exotic...
Studies of the Shapes of Heavy Nuclei at ISOLDE
NASA Astrophysics Data System (ADS)
Butler, Peter A.
For certain combinations of protons and neutrons there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a "pear-shape" in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). In this talk I will briefly review the historic evidence for reflection asymmetry in nuclei and describe how recent experiments carried out at REX-ISOLDE have constrained nuclear theory and how they contribute to tests of extensions of the Standard Model. I will also discuss future prospects for measuring nuclear shapes from Coulomb Excitation: experiments are being planned that will exploit beams from HIE-ISOLDE that are cooled in the TSR storage ring and injected into a solenoidal spectrometer similar to the HELIOS device developed at the Argonne National Laboratory.
Bio-Invasions: The Spread of Exotic Species.
ERIC Educational Resources Information Center
Bright, Chris
1995-01-01
Human mobility has radically increased the rate at which large numbers of living things are moving from one ecosystem to another. Discusses how ecosystems change when "exotic" species invade natural communities and notes efforts to control adverse effects. (LZ)
Exotic grasslands on reclaimed midwestern coal mines: An ornithological perspective
Scott, P.E.; Lima, S.L.
2004-07-01
The largest grasslands in Indiana and Illinois are on reclaimed surface coal mines, which are numerous in the Illinois Coal Basin. The reclamation goal of establishing a vegetation cover with inexpensive, hardy exotic grass species (e.g., tall fescue, smooth brome) inadvertently created persistent, large grassland bird refuges. We review research documenting the importance of these sites for native prairie birds. On mines, grassland specialist birds (restricted to grassland throughout their range) prefer sites dominated by exotic grasses to those rich in forbs, whereas nonspecialist bird species show no significant preference. Midwestern mine grasslands potentially could be converted into landscapes that include native warm-season grasses and forbs adapted to the relatively dry, poor soil conditions, in addition to the present successful exotic grass stands. A key question is whether native mixtures will resist conversion to forb-rich or woody growth over the long term, as the exotic grasses have done.
Magicity of neutron-rich nuclei within relativistic self-consistent approaches
NASA Astrophysics Data System (ADS)
Li, Jia Jie; Margueron, Jérôme; Long, Wen Hui; Van Giai, Nguyen
2016-02-01
The formation of new shell gaps in intermediate mass neutron-rich nuclei is investigated within the relativistic Hartree-Fock-Bogoliubov theory, and the role of the Lorentz pseudo-vector and tensor interactions is analyzed. Based on the Foldy-Wouthuysen transformation, we discuss in detail the role played by the different terms of the Lorentz pseudo-vector and tensor interactions in the appearing of the N = 16, 32 and 34 shell gaps. The nuclei 24O, 48Si and 52,54Ca are predicted with a large shell gap and zero (24O, 52Ca) or almost zero (48Si, 54Ca) pairing gap, making them candidates for new magic numbers in exotic nuclei. We find from our analysis that the Lorentz pseudo-vector and tensor interactions induce very specific evolutions of single-particle energies, which could clearly sign their presence and reveal the need for relativistic approaches with exchange interactions.
Structural evolution in transitional nuclei of mass 82 ≤A ≤132
NASA Astrophysics Data System (ADS)
Bhuyan, M.
2015-09-01
In this theoretical study, we report an investigation on the behavior of two-neutron separation energy, a differential variation of the nucleon separation energy, the nuclear charge radii, and the single-particle energy levels along the isotopic chains of transitional nuclei. We have used the relativistic mean-field formalism with NL3 and NL3* forces for this present analysis. The study refers to the even-even nuclei such as Zr, Mo, Ru, and Pd for N =42 -86 , where a rich collective phenomena such as proton radioactivity, cluster or nucleus radioactivity, exotic shapes, island of inversion, etc. are observed. We found that there are few nonmonotonic aspects over the isotopic chain, which are correlated with the structural properties such as shell/subshell closures, the shape transition, clustering, magicity, etc. In addition to these, we have shown the internal configuration of these nuclei to get a further insight into the reason for these discrepancies.
Controlling the exotic diseases: 2. Nursing management.
Best, H R; Clayton, A J
1980-11-01
Advance planning can facilitate the care of a patient with an exotic disease who is admitted to a hospital that lacks facilities for high-security isolation. The Department of National Health and Welfare contingency plan for dealing with such patients lacks specific information in a number of areas of medical care, as described in this paper. Consideration must be given to the number of personnel trained and readied for employment, the criteria for selection and special preparation. The protective clothing generally used for hospital isolation procedures is inadequate. Several types of special clothing, including a respirator, are available for total protection of personnel; the clothing may be uncomfortable when worn for long periods, and does restrict movement, vision and communication. All persons entering the isolation suite must change into fully protective clothing, and double layers of clothing are required for direct patient care. All personnel must shower and change before leaving the isolation suite. Suitable facilities for dressing and showering, together with entry and exit routines, must be considered. Hand washing, daily cleaning procedures and disposal of liquid and solid wastes all require special procedures. The social and psychologic problems of patients and their families must also be considered. Preplanning is required to decrease the risks involved in monitoring vital signs and implementing emergency procedures requiring contact with the patient's blood. PMID:7437990
Improving Qubit Quality Factors Through Exotic Materials
NASA Astrophysics Data System (ADS)
Norman, Victoria
In the time since the first qubits were successfully fabricated, the coherence times of superconducting Josephson junction qubits have improved by several orders of magnitude. Yet as the quantum information and computation field moves forward, these coherence times still need further improvement. We are now finding that in some superconducting systems, non-thermal equilibrium quasiparticles are becoming the limiting factor in qubit lifetimes. For SIS superconducting qubits, the T1 and T2* values may be improved by the use of materials with higher superconducting band gap, EG, for which low values may allow for quasiparticles to break up cooper pairs more easily, leading to a shorter lifetime. At this time, Al-Al2Ox3-Al transmons are very well characterized and understood and will therefore serve as an appropriate baseline with which to compare the more exotic junction materials. Using tantalum and niobium, which have Eg values of 3 times and 10 times that of aluminum respectively, we expect the T1 and T2* values to increase significantly for the Al-Al2Ox3-Nb, Al-Al2Ox3-Ta, and Ta-Ta2Ox5-Nb qubits.
Using exotic atoms to keep borders safe
Jason, A; Miyadera, H; Esch, E I; Hoteling, N J; Adelmann, A; Heffner, R H; Green, A; Olsthoorn, J; Stocki, T J
2010-01-01
Muons, created by a particle accelerator, can be used to scan cargo for special nuclear materials (SNM). These muons exist long enough and are penetrating enough that they can be used to actively scan cargo to ensure the non-proliferation of SNM. A set of 'proof-of-concept' experiments have been performed to show that active muon analysis can be used. Experiments were performed at high intensity, medium energy particle accelerators (TRIUMF and PSI). Negative muons form exotic atoms with one electron replaced by the muon. Since the muon is captured in an excited state, it will give off x-rays which can be detected by high purity germanium detectors. These characteristic x-rays can be used to identify the nuclide. The muonic x-rays corresponding to the SNM of interest have been measured, even with the use of various shielding configurations composed of lead, iron, polyethylene, or fiberglass. These preliminary results show that muons can be successfully used to find shielded SNM. The safety of North Americans can be protected by the use of this technology.
Exotic differentiable structures and general relativity
NASA Astrophysics Data System (ADS)
Brans, Carl H.; Randall, Duane
1993-02-01
We review recent developments in differential topology with special concern for their possible significance to physical theories, especially general relativity. In particular we are concerned here with the discovery of the existence of non-standard (“fake” or “exotic”) differentiable structures on topologically simple manifolds such asS 7, ℝ4 andS 3 X ℝ1. Because of the technical difficulties involved in the smooth case, we begin with an easily understood toy example looking at the role which the choice of complex structures plays in the formulation of two-dimensional vacuum electrostatics. We then briefly review the mathematical formalisms involved with differentiable structures on topological manifolds, diffeomorphisms and their significance for physics. We summarize the important work of Milnor, Freedman, Donaldson, and others in developing exotic differentiable structures on well known topological manifolds. Finally, we discuss some of the geometric implications of these results and propose some conjectures on possible physical implications of these new manifolds which have never before been considered as physical models.
Exotic muon decays and the KARMEN anomaly
NASA Astrophysics Data System (ADS)
Gninenko, S. N.; Krasnikov, N. V.
1998-08-01
An anomaly in time distribution of neutrinos from the ISIS pulsed beam stop source observed by the KARMEN collaboration is discussed. We show that the anomaly can be interpreted as a superposition of two exponentials, both having time constants consistent with the μ+ lifetime of 2.2 μs. It is assumed that they both originate from muon decays at rest. One of them describes the time distribution of the prompt neutrino events, while the other describes the time distribution of events from delayed decays of slowly moving (β~=0.02) particles in the KARMEN calorimeter. We propose here that these particles are produced in exotic decays of positive muons μ+-->e++X, resulting in the second exponential time distribution shifted by the time of flight with respect to the time distribution of neutrino events. This model gives an acceptable fit to the KARMEN data if X has a mass of 103.9 MeV. The possible decay modes of this new massive neutral particle are discussed. This hypothesis can be experimentally tested in the near future by studying the low energy part of the e+ spectrum in the μ+ decays.
Using anti pp annihilation to find exotic mesons
Sharpe, S.R.
1987-10-01
Present data suggests that a number of mesons have been found which cannot be accommodated in standard anti qq multiplets. Theory suggests that such exotic mesons should exist in the spectrum of Quantum Chromodynamics, but provides little guide to their properties. It is argued that a high luminosity, low energy anti pp machine would be a powerful tool with which to search for such exotics.
Highly excited and exotic meson spectroscopy from lattice QCD
Christopher Thomas
2011-05-01
I will discuss recent progress in extracting highly excited and exotic meson spectra using lattice QCD. New results in the light meson sector will be presented, where a combination of techniques have enabled us to confidently identify the spin of extracted states. Highlights include many states with exotic quantum numbers and, for the first time in a lattice QCD calculation, spin-four states. I will conclude with comments on future prospects.
The mass formula for an exotic BTZ black hole
NASA Astrophysics Data System (ADS)
Zhang, Baocheng
2016-04-01
An exotic Bañados-Teitelboim-Zanelli (BTZ) black hole has an angular momentum larger than its mass in three dimension (3D), which suggests the possibility that cosmic censorship could be violated if angular momentum is extracted by the Penrose process. In this paper, we propose a mass formula for the exotic BTZ black hole and show no violation of weak cosmic censorship in the gedanken process above by understanding properly its mass formula. Unlike the other black holes, the total energy of the exotic BTZ black hole is represented by the angular momentum instead of the mass, which supports a basic point of view that the same geometry should be determined by the same energy in 3D general relativity whose equation of motion can be given either by normal 3D Einstein gravity or by exotic 3D Einstein gravity. However, only the mass of the exotic black hole is related to the thermodynamics and other forms of energy are "dumb", which is consistent with the earlier thermodynamic analysis about exotic black holes.
Effects of exotic species on Yellowstone's grizzly bears
Reinhart, D.P.; Haroldson, Mark A.; Mattson, D.J.; Gunther, Kerry A.
2001-01-01
Humans have affected grizzly bears (Ursus arctos horribilis) by direct mortality, competition for space and resources, and introduction of exotic species. Exotic organisms that have affected grizzly bears in the Greater Yellowstone Area include common dandelion (Taraxacum officinale), nonnative clovers (Trifolium spp.), domesticated livestock, bovine brucellosis (Brucella abortus), lake trout (Salvelinus namaycush), and white pine blister rust (Cronartium ribicola). Some bears consume substantial amounts of dandelion and clover. However, these exotic foods provide little digested energy compared to higher-quality bear foods. Domestic livestock are of greater energetic value, but use of this food by bears often leads to conflicts with humans and subsequent increases in bear mortality. Lake trout, blister rust, and brucellosis diminish grizzly bears foods. Lake trout prey on native cutthroat trout (Oncorhynchus clarkii) in Yellowstone Lake; white pine blister rust has the potential to destroy native whitebark pine (Pinus albicaulis) stands; and management response to bovine brucellosis, a disease found in the Yellowstone bison (Bison bison) and elk (Cervus elaphus), could reduce populations of these 2 species. Exotic species will likely cause more harm than good for Yellowstone grizzly bears. Managers have few options to mitigate or contain the impacts of exotics on Yellowstones grizzly bears. Moreover, their potential negative impacts have only begun to unfold. Exotic species may lead to the loss of substantial highquality grizzly bear foods, including much of the bison, trout, and pine seeds that Yellowstone grizzly bears currently depend upon.
NASA Technical Reports Server (NTRS)
Rahe, J.; Vanysek, V.; Weissman, P. R.
1994-01-01
Active long- and short-period comets contribute about 20 to 30 % of the major impactors on the Earth. Cometary nuclei are irregular bodies, typically a few to ten kilometers in diameter, with masses in the range 10(sup 15) to 10(sup 18) g. The nuclei are composed of an intimate mixture of volatile ices, mostly water ice and hydrocarbon and silicate grains. The composition is the closest to solar composition of any known bodies in the solar system. The nuclei appear to be weakly bonded agglomerations of smaller icy planetesimals, and material strengths estimated from observed tidal disruption events are fairly low, typically 10(sup 2) to 10(sup 4) N m(sup -2). Density estimates range between 0.2 and 1.2 g cm(sup -3) but are very poorly determined, if at all. As comets age they develop nonvolitile crusts on their surfaces which eventually render them inactive, similar in appearance to carbonaceous asteroids. However, dormant comets may continue to show sporadic activity and outbursts for some time before they become truly extinct. The source of the long-period comets is the Oort cloud, a vast spherical cloud of perhaps 10(sup 12) to 10(sup 13) comets surrounding the solar system and extending to interstellar distances. The likely source for short-period comets is the Kuiper belt. a ring of perhaps 10(sup 8) to 10(sup 10) remnant icy planetesimals beyond the orbit of Neptune, though some short-period comets may also be long-period comets from the Oort cloud which have been perturbed into short-period orbits.
Electroproduction of Strange Nuclei
E.V. Hungerford
2002-06-01
The advent of high-energy, CW-beams of electrons now allows electro-production and precision studies of nuclei containing hyperons. Previously, the injection of strangeness into a nucleus was accomplished using secondary beams of mesons, where beam quality and target thickness limited the missing mass resolution. We review here the theoretical description of the (e, e'K+) reaction mechanism, and discuss the first experiment demonstrating that this reaction can be used to precisely study the spectra of light hypernuclei. Future experiments based on similar techniques, are expected to attain even better resolutions and rates.
Total photoabsorption in nuclei
Bianchi, N.
1992-06-01
The Frascati-Genova collaboration proposes to measure the total photonuclear cross section on a wide range of nuclei between 500 MeV and 2 GeV, to obtain informations on the interaction of baryon resonances with nucleons and on the onset of the shadowing effect. The experiment could be performed in the Hall B as soon as the tagging facility will be ready and before the end of the installation of the CLAS spectrometer. The requirements for the photon beam, like maximum energy, intensity and beam definition, are not so strong so that the experiment would also be a good first test of the tagged photon facility.
Catara, F.; Sambataro, M. Italy Dipartimento di Fisica dell'Universita, 95129 Catania )
1992-08-01
By making use of a mapping procedure recently proposed, we construct the nucleon image of the one-body quark density operator in the framework of the nonrelativistic quark model of the nucleons. We evaluate the expectation value of this operator in the ground state of the doubly magic nuclei {sup 4}He, {sup 16}O, and {sup 40}Ca described within the nuclear shell model. We analyze the role of quark exchanges between nucleons. We also investigate the effect on the quark density of short-range correlations in the nuclear wave functions as well as of variations in the nucleon size.
Shell energy and the level-density parameter of hot nuclei
Nerlo-Pomorska, Bozena; Pomorski, Krzysztof; Bartel, Johann
2006-09-15
Macroscopic-microscopic calculations have been performed with the Yukawa folded mean field for 134 spherical even-even nuclei and 6 deformed ones at temperatures 0{<=}T{<=}5 MeV and elongations ranging from oblate shapes to the scission configuration of fissioning nuclei. The Strutinsky type free-energy shell corrections for this sample of nuclei and their temperature and deformation dependence are found by a folding procedure in particle-number space. The average dependence of the single-particle level-density parameter on mass number A and isospin I is determined and compared with previous estimates obtained using the relativistic mean-field theory, the Hartree-Fock approximation with the Skyrme effective interaction, and the phenomenological Thomas-Fermi approach adjusted to experimental data. The estimates for the level-density parameter obtained for different deformations are fitted by a liquid-drop type expression.
Calculations of {alpha}-decay half-lives for heavy and superheavy nuclei
Qian Yibin; Ni Dongdong; Ren, Zhongzhou
2011-04-15
Systematic calculations on the {alpha}-decay half-lives of heavy and superheavy nuclei are performed within a deformed version of the cluster model, using the modified two-potential approach. The deformed Woods-Saxon potential is employed to calculate the {alpha}-decay width through a deformed barrier. For comparison the calculated {alpha}-decay half-lives in the empirical relations are also presented. The present study is initially restricted to even-even nuclei in the heavy mass region with N>126. Then the study is extended to the recently observed heaviest nuclei, including synthesized superheavy elements and isotopes. The {alpha}-decay half-lives obtained are found to be in good agreement with the experimental data.
Low lying electric dipole excitations in nuclei of the rare earth region
von Brentano, P.; Zilges, A.; Herzberg, R.D. . Inst. fuer Kernphysik); Zamfir, N.V. ); Kneissl, U.; Heil, R.D.; Pitz, H.H. . Inst. fuer Strahlenphysik); Wesselborg, C. . Inst. fuer Kernphysik)
1992-01-01
From many experiments with low energy photon scattering on deformed rare earth nuclei we have obtained detailed information about the distribution of electric dipole strength below 4 MeV. Apart from some weaker transitions between 2 and 4 MeV we observed one, and sometimes two, very strong El-groundstate transitions around 1.5 MeV in all examined nuclei. They arise from the de-excitation of the bandheads of the (J[sup [pi
Study of Nuclei far From Stability by Using the CHIMERA 4{pi} Detector and Radioactive Beams at LNS
Cardella, G.; De Filippo, E.; Pagano, A.; Papa, M.; Pirrone, S.; Verde, G.; Amorini, F.; Anzalone, A.; Maiolino, C.; Auditore, L.; Loria, D.; Trifiro, A.; Trimarchi, M.; Cavallaro, S.; Lombardo, I.; Porto, F.; Rizzo, F.; Russotto, P.; Chatterjee, M. B.; Geraci, E.
2009-08-26
At LNS are available radioactive beams at tandem and intermediate energies provided respectively by the EXCYT and by the fragmentation FRIBS facilities. Using these beams, and the 4{pi} detector CHIMERA, we want to study excitation and decay of resonances in light exotic nuclei populated with pick-up stripping and other reaction mechanisms. Some preliminary results obtained with stable and unstable beams are reported.
Ticks imported to Europe with exotic reptiles.
Mihalca, Andrei Daniel
2015-09-30
It is known that traded exotic animals carry with them an immense number of associated symbionts, including parasites. Reptiles are no exception. Most of the imported reptiles originate from tropical countries and their possibility to carry potentially dangerous pathogens is high. According to CITES, Europe is currently the main reptile importer in the world. Despite this, there is no review or analysis available for the risk related to the importation of tick-borne diseases with traded reptile to the EU. The main aim of the manuscript is to provide a review on the available literature on ticks introduced to and exchanged between European countries via the live reptile trade. So far, the published reports of ticks imported on reptiles are limited to few European countries: Italy, Poland, Spain, Netherlands, Belgium, Slovenia and UK. The following species have been reported: Hyalomma aegyptium, Amblyomma dissimile, Amblyomma exornatum, Amblyomma flavomaculatum, Amblyomma fuscolineatum, Amblyomma latum, Amblyomma quadricavum, Amblyomma marmoreum, Amblyomma nuttalli, Amblyomma sparsum, Amblyomma sphenodonti, Amblyomma transversale and Amblyomma varanense. The majority of species are of African origin, followed by American and Asian species. All groups of reptiles (chelonians, snakes, lizards, crocodiles, tuataras) were involved. However, it seems that certain groups (i.e. tortoises of genus Testudo, monitor lizards of genus Varanus, snakes of genus Python) are more important as host for imported ticks, but this may be related to higher levels of international trade. Even fewer are the reports of tick-borne pathogens associated with imported reptile ticks. Despite the diversity of tick species reported on imported reptiles, the situations of truly invasive species are atypical and are limited in natural environments to maximum two cases where H. aegyptium was involved. Otherwise, the risk associated with reptile trade for introduction of invasive tick to Europe is low
Study of multi-nucleon transfer reactions with light nuclei
Benzoni, G.; Montanari, D.; Bracco, A.; Blasi, N.; Camera, F.; Crespi, F. C. L.; Corsi, A.; Leoni, S.; Million, B.; Nicolini, R.; Wieland, O.; Zalite, A.; Zocca, F.; Azaiez, F.; Franchoo, S.; Stefan, I.; Ibrahim, F.; Verney, D.; Battacharyya, S.; De France, G.
2008-05-12
Multi-nucleon transfer reactions are useful tools to populate exotic nuclei, particularly the neutron-rich ones. In this view, two different experiments have been performed employing a stable ({sup 22}Ne) and a radioactive ({sup 24}Ne) beam, both impinging on a {sup 208}Pb target. The first reaction has been studied using the CLARA-PRISMA-DANTE set-up at Laboratori Nazionali di Legnaro (Legnaro-Italy), while the second reaction was performed at Ganil (Caen-France) employing a SPIRAL radioactive beam of {sup 24}Ne. In this case recoils and coincident {gamma} rays were detected with the VAMOS-EXOGAM set-up.The data show that MNT reactions can selectively populate states of different nature and, therefore, are a good tool to study nuclear structure further away from stability.
Projected Shell Model Study of Yrast States of Neutron-Deficient Odd-Mass Pr Nuclei
Ibanes, A.; Ortiz, Mark E; Velazquez, V.; Galindo-Uribarri, Alfredo {nmn}; Hess, P. O.; Sun, Y.
2011-01-01
A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A = 130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the 125,127,129,131,133Pr isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J (2), kinetic moment of inertia J (1), the crossing of rotational bands, and backbending effects.
Projected shell model study of yrast states of neutron-deficient odd-mass Pr nuclei
Ibanez-Sandoval, A.; Ortiz, M. E.; Velazquez, V.; Galindo-Uribarri, A.; Hess, P. O.; Sun, Y.
2011-03-15
A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A=130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the {sup 125,127,129,131,133}Pr isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J{sup (2)}, kinetic moment of inertia J{sup (1)}, the crossing of rotational bands, and backbending effects.
Projected shell model study of yrast states of neutron-deficient odd-mass Pr nuclei
NASA Astrophysics Data System (ADS)
Ibáñez-Sandoval, A.; Ortiz, M. E.; Velázquez, V.; Galindo-Uribarri, A.; Hess, P. O.; Sun, Y.
2011-03-01
A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A=130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the Pr125,127,129,131,133 isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J(2), kinetic moment of inertia J(1), the crossing of rotational bands, and backbending effects.
Deformation properties with a finite-range simple effective interaction
NASA Astrophysics Data System (ADS)
Behera, B.; Viñas, X.; Routray, T. R.; Robledo, L. M.; Centelles, M.; Pattnaik, S. P.
2016-08-01
Deformed and spherical even-even nuclei are studied using a finite-range simple effective interaction within the Hartree-Fock-Bogoliubov mean-field approach. Different parameter sets of the interaction, corresponding to different incompressibility, are constructed by varying the exponent γ of the density in the traditional density-dependent term. Ten of the 12 parameters of these interactions are determined from properties of asymmetric nuclear matter and spin-polarized pure neutron matter. The two remaining parameters are fitted to reproduce the experimental binding energies known in 620 even-even nuclei using several variants of the rotational energy correction. The rms deviations for the binding energy depend on the value of γ and the way the rotational energy correction is treated but they can be as low as 1.56 MeV, a value competitive with other renowned effective interactions of Skyrme and Gogny type. Charge radii are compared to the experimental values of 313 even-even nuclei and the rms deviation is again comparable and even superior to the one of popular Skyrme and Gogny forces. Emphasis is given to the deformation properties predicted with these interactions by analyzing the potential energy surfaces for several well deformed nuclei and the fission barriers of some nuclei. Comparison of the results with the experimental information, where available, as well as with the results of the Gogny D1S force, shows satisfactory agreement.
Relativistic Energy Density Functionals: beyond mean-field description of exotic structures
Vretenar, D.; Niksic, T.; Ring, P.; Lalazissis, G. A.
2009-01-28
The framework of relativistic energy density functionals is extended to include correlations related to the restoration of broken symmetries and to fluctuations of collective variables. The generator coordinate method is used to perform configuration mixing of angular-momentum and particle-number projected relativistic wave functions. This approach enables a quantitative description of the evolution of shell-structure, deformation and shape coexistence phenomena in nuclei with soft potential energy surfaces, and singular properties of excitation spectra and transition rates at critical points of quantum shape phase transitions.
{alpha} decay chains in {sup 271-294}115 superheavy nuclei
Santhosh, K. P.; Priyanka, B.; Joseph, Jayesh George; Sahadevan, Sabina
2011-08-15
{alpha} decay of {sup 271-294}115 superheavy nuclei is studied using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The predicted {alpha} half-lives of {sup 287}115 and {sup 288}115 nuclei and their decay products are in good agreement with experimental values. Comparison of {alpha} and spontaneous fission half-lives predicts four-{alpha} chains and three-{alpha} chains, respectively, from {sup 287}115 and {sup 288}115 nuclei and are in agreement with experimental observation. Our study predicts two-{alpha} chains from {sup 273,274,289}115, three-{alpha} chains from {sup 275}115, and four-{alpha} chains consistently from {sup 284,285,286}115 nuclei. These observations will be useful for further experimental investigation in this region.
Shell structure of one-particle resonances in deformed potentials
NASA Astrophysics Data System (ADS)
Hamamoto, Ikuko
2016-05-01
The shell structure of low-lying neutron resonance levels in axially symmetric quadrupole-deformed potentials is discussed, which seems analogous to that of weakly bound neutrons. As numerical examples, nuclei slightly outside the neutron drip line, 27 12 39Mg and 15 6 21C, are studied. For the lowest resonance I obtain Iπ=Ωπ=5 /2- for 39Mg which is likely to be prolately deformed, while Iπ=Ωπ=1 /2+ may be assigned to the nucleus 21C which may be oblately deformed. Consequently, 21C will not be observed as a recognizable resonance state, in agreement with the experimental information.
Isolation of nuclei from yeast.
Bhargava, M M; Halvorson, H O
1971-05-01
A method for isolation of nuclei from Saccharomyces cervisiae in high yield is described. The DNA/protein ratio of the isolated nuclei is 10 times higher than that of whole cells. Examination of these nuclei in phase and electron microscopes has shown them to be round bodies having a double membrane, microtubules, and a dark crescent at one end. The optimum conditions for extraction and resolution of histones of these nuclei on acrylamide gels have been investigated. The nuclei have an active RNA polymerase (E.C. 2.7.7.6) and are able to synthesize RNA in vitro. They are also readily stainable with Giemsa's, Feulgen's, and acridine orange methods. PMID:19866769
NASA Astrophysics Data System (ADS)
Holt, Roy J.
2016-03-01
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.
ALPI Setup as the SPES Accelerator of Exotic Beams
NASA Astrophysics Data System (ADS)
Bisoffi, G.; Bassato, G.; Battistella, A.; Bermudez, J.; Bortolato, D.; Canella, S.; Chalykh, B.; Comunian, M.; Facco, A.; Fagotti, E.; Galatà, A.; Giacchini, M.; Gramegna, F.; Lamy, T.; Modanese, P.; Palmieri, A.; Pengo, R.; Pisent, A.; Poggi, M.; Porcellato, A.; Roncolato, C.; Scarpa, D.
2014-03-01
The SPES (Selective Production of Exotic Species) project for a national exotic beam facility in Legnaro includes pivotal upgrades of the existing superconducting linac ALPI (Acceleratore Lineare Per Ioni), to make it appropriate as the RIB (Radioactive Ion Beam) accelerator. The new injector, consisting of an Electron Cyclotron Resonance (ECR)-type charge breeder and a radiofrequency quadrupole (RFQ), will be described. Upgrade measures in ALPI to improve beam transmission and final energy, and handle low-intensity RIB will be explained, with the aim of increasing transmission to T > 90%, Ef by ~ 20%, reaching 10 MeV/u for the reference beam 132Sn.
Annihilation physics of exotic galactic dark matter particles
NASA Technical Reports Server (NTRS)
Stecker, F. W.
1990-01-01
Various theoretical arguments make exotic heavy neutral weakly interacting fermions, particularly those predicted by supersymmetry theory, attractive candidates for making up the large amount of unseen gravitating mass in galactic halos. Such particles can annihilate with each other, producing secondary particles of cosmic-ray energies, among which are antiprotons, positrons, neutrinos, and gamma-rays. Spectra and fluxes of these annihilation products can be calculated, partly by making use of positron electron collider data and quantum chromodynamic models of particle production derived therefrom. These spectra may provide detectable signatures of exotic particle remnants of the big bang.
More on wormholes supported by small amounts of exotic matter
Kuhfittig, Peter K.F.
2006-04-15
Recent papers by Fewster and Roman have emphasized that wormholes supported by arbitrarily small amounts of exotic matter will have to be incredibly fine-tuned if they are to be traversable. This paper discusses a wormhole model that strikes a balance between two conflicting requirements, reducing the amount of exotic matter and fine-tuning the metric coefficients, ultimately resulting in an engineering challenge: one requirement can only be met at the expense of the other. The wormhole model is macroscopic and satisfies various traversability criteria.
Exotic plant species invade hot spots of native plant diversity
Stohlgren, T.J.; Binkley, D.; Chong, G.W.; Kalkhan, M.A.; Schell, L.D.; Bull, K.A.; Otsuki, Y.; Newman, G.; Bashkin, M.; Yowhan, S.
1999-01-01
Some theories and experimental studies suggest that areas of low plant species richness may be invaded more easily than areas of high plant species richness. We gathered nested-scale vegetation data on plant species richness, foliar cover, and frequency from 200 1-m2 subplots (20 1000-m2 modified-Whittaker plots) in the Colorado Rockies (USA), and 160 1-m2 subplots (16 1000-m2 plots) in the Central Grasslands in Colorado, Wyoming, South Dakota, and Minnesota (USA) to test the generality of this paradigm. At the 1-m2 scale, the paradigm was supported in four prairie types in the Central Grasslands, where exotic species richness declined with increasing plant species richness and cover. At the 1-m2 scale, five forest and meadow vegetation types in the Colorado Rockies contradicted the paradigm; exotic species richness increased with native-plant species richness and foliar cover. At the 1000-m2 plot scale (among vegetation types), 83% of the variance in exotic species richness in the Central Grasslands was explained by the total percentage of nitrogen in the soil and the cover of native plant species. In the Colorado Rockies, 69% of the variance in exotic species richness in 1000-m2 plots was explained by the number of native plant species and the total percentage of soil carbon. At landscape and biome scales, exotic species primarily invaded areas of high species richness in the four Central Grasslands sites and in the five Colorado Rockies vegetation types. For the nine vegetation types in both biomes, exotic species cover was positively correlated with mean foliar cover, mean soil percentage N, and the total number of exotic species. These patterns of invasibility depend on spatial scale, biome and vegetation type, spatial autocorrelation effects, availability of resources, and species-specific responses to grazing and other disturbances. We conclude that: (1) sites high in herbaceous foliar cover and soil fertility, and hot spots of plant diversity (and
Exotic hadron production in a quark combination model
Han Wei; Shao Fenglan; Li Shiyuan; Shang Yonghui; Yao Tao
2009-09-15
The philosophy on production of exotic hadrons (multiquark states) in the framework of the quark combination model is investigated, taking f{sub 0}(980) as an example. The production rate and p{sub T} spectra of f{sub 0}(980) considered as (ss) or (sqsq), respectively, are calculated and compared in Au+Au collisions at {radical}(s{sub NN})=200 GeV. The unitarity of various combination models, when open for exotic hadron production, is addressed.
Exotic mesons in /bar N/N annihilation
Dover, C.B.
1988-01-01
We investigate the utility of the antinucleon-nucleon (/bar N/N) annihilation process as a means of producing exotic (non /bar Q/Q) mesons. Several examples are considered of J/sup ..pi..//sup C/ exotic formation in the /bar p/p ..-->.. ..pi..X reaction. We emphasize the usefulness of quantum number filtration, achieved by preparing the initial /bar p/p atom in tagged L = 0,1 states and focusing on selected exclusive final states. 36 refs., 4 tabs.
Exotic Paired States with Anisotropic Spin-Dependent Fermi Surfaces
Feiguin, Adrian E.; Fisher, Matthew P. A.
2009-07-10
We propose a model for realizing exotic paired states in cold Fermi gases by using a spin-dependent optical lattice to engineer mismatched Fermi surfaces for each hyperfine species. The BCS phase diagram shows a stable paired superfluid state with coexisting pockets of momentum space with gapless unpaired carriers, similar to the Sarma state in polarized mixtures, but in our case the system is unpolarized. We propose the possible existence of an exotic 'Cooper-pair Bose-metal' phase, which has a gap for single fermion excitations but gapless and uncondensed 'Cooper-pair' excitations residing on a 'Bose surface' in momentum space.
Extended Locus of Regular Nuclei
Amon, L.; Casten, R. F.
2007-04-23
A new family of IBM Hamiltonians, characterized by certain parameter values, was found about 15 years ago by Alhassid and Whelan to display almost regular dynamics, and yet these solutions to the IBM do not belong to any of the known dynamical symmetry limits (vibrational, rotational and {gamma} - unstable). Rather, they comprise an 'Arc of Regularity' cutting through the interior of the symmetry triangle from U(5) to SU(3) where suddenly there is a decrease in chaoticity and a significant increase in regularity. A few years ago, the first set of nuclei lying along this arc was discovered. The purpose of the present work is to search more broadly in the nuclear chart at all nuclei from Z = 40 - 100 for other examples of such 'regular' nuclei. Using a unique signature for such nuclei involving energy differences of certain excited states, we have identified an additional set of 12 nuclei lying near or along the arc. Some of these nuclei are known to have low-lying intruder states and therefore care must be taken, however, in judging their structure. The regularity exhibited by nuclei near the arc presumably reflects the validity or partial validity of some new, as yet unknown, quantum number describing these systems and giving the regularity found for them.
Shape coexistence in atomic nuclei
Heyde, Kris; Wood, John L.
2011-10-01
Shape coexistence in nuclei appears to be unique in the realm of finite many-body quantum systems. It differs from the various geometrical arrangements that sometimes occur in a molecule in that in a molecule the various arrangements are of the widely separated atomic nuclei. In nuclei the various ''arrangements'' of nucleons involve (sets of) energy eigenstates with different electric quadrupole properties such as moments and transition rates, and different distributions of proton pairs and neutron pairs with respect to their Fermi energies. Sometimes two such structures will ''invert'' as a function of the nucleon number, resulting in a sudden and dramatic change in ground-state properties in neighboring isotopes and isotones. In the first part of this review the theoretical status of coexistence in nuclei is summarized. Two approaches, namely, microscopic shell-model descriptions and mean-field descriptions, are emphasized. The second part of this review presents systematic data, for both even- and odd-mass nuclei, selected to illustrate the various ways in which coexistence is observed in nuclei. The last part of this review looks to future developments and the issue of the universality of coexistence in nuclei. Surprises continue to be discovered. With the major advances in reaching to extremes of proton-neutron number, and the anticipated new ''rare isotope beam'' facilities, guidelines for search and discovery are discussed.
Ab initio many-body calculations of light nuclei neutron and proton scattering
NASA Astrophysics Data System (ADS)
Quaglioni, Sofia
2008-10-01
One of the greatest challenges of nuclear physics today is the development of a quantitative microscopic theory of low-energy reactions on light nuclei. At the same time, technical progress on the theoretical front is urgent to match the major experimental advances in the study of exotic nuclei at the radioactive beam facilities. We build a new ab initio many-body approachootnotetextS. Quaglioni and P. Navratil, arXiv:0804.1560. capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group methodootnotetextY. C. Tang et al., Phys. Rep. 47, 167 (1978); K. Langanke and H. Friedrich, Advances in Nuclear Physics, chapter 4., Plenum, New York, 1987. with the ab initio no-core shell model.ootnotetextP. Navratil, J. P. Vary, and B. R. Barrett, Phys. Rev. Lett. 84, 5728 (2000); Phys. Rev. C 62, 054311 (2000).. In this way, we complement a microscopic-cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, while preserving Pauli principle and translational symmetry. I will present results for neutron and proton scattering on light nuclei, including n- and p-^4He phase shifts, and low-lying states of one-neutron halo p-shell nuclei, obtained using realistic nucleon-nucleon potentials. In particular, I will address the parity inversion of the ^11Be ground state.
Ayala, A.L.; Ducati, M.B.G.; Levin, E.M.
1996-10-01
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.
Self-consistent description of coexistence phenomena in medium mass nuclei
Petrovici, A.; Schmid, K. W.; Faessler, Amand; Andrei, O.
2010-11-24
Shape coexistence and mixing, isospin mixing, the competition between neutron-proton and like-nucleon pairing correlations have been identified as the main characteristic features of nuclei near the N = Z line in the A{approx_equal}70 mass region. The self-consistent treatment of exotic phenomena dominated by their interplay represents a challenge for the nuclear many-body models. The realistic description of tiny effects in this mass region aiming to test the fundamental interactions and symmetries as well as the required theoretical predictions concerning the nuclear properties relevant for astrophysical scenarios are still open problems of the low-energy nuclear physics today.
Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?
Seabloom, Eric W.
2013-08-14
Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species. Here, we used a globally replicated study to quantify relationships between exotic richness and abundance in grass-dominated ecosystems in 13 countries on six continents, ranging from salt marshes to alpine tundra. We tested effects of human land use, native community diversity, herbivore pressure, and nutrient limitation on exotic plant dominance. Despite its widespread use, exotic richness was a poor proxy for exotic dominance at low exotic richness, because sites that contained few exotic species ranged from relatively pristine (low exotic richness and cover) to almost completely exotic-dominated ones (low exotic richness but high exotic cover). Both exotic cover and richness were predicted by native plant diversity (native grass richness) and land use (distance to cultivation). Although climate was important for predicting both exotic cover and richness, climatic factors predicting cover (precipitation variability) differed from those predicting richness (maximum temperature and mean temperature in the wettest quarter). Herbivory and nutrient limitation did not predict exotic richness or cover. Exotic dominance was greatest in areas with low native grass richness at the site- or regional-scale. Although this could reflect native grass displacement, a lack of biotic resistance is a more likely explanation, given that grasses comprise the most aggressive invaders. These findings underscore the need to move beyond richness as a surrogate for the extent of invasion, because this metric confounds monodominance with invasion resistance. Monitoring
Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?
Seabloom, Eric; Borer, Elizabeth; Buckley, Yvonne; Cleland, Elsa E.; Davies, Kendi; Firn, Jennifer; Harpole, W. Stanley; Hautier, Yann; Lind, Eric M.; MacDougall, Andrew; Orrock, John L.; Prober, Suzanne M.; Adler, Peter; Alberti, Juan; Anderson, T. Michael; Bakker, Jonathan D.; Biederman, Lori A.; Blumenthal, Dana; Brown, Cynthia S.; Brudvig, Lars A.; Caldeira, Maria; Chu, Cheng-Jin; Crawley, Michael J.; Daleo, Pedro; Damschen, Ellen Ingman; D'Antonio, Carla M.; DeCrappeo, Nicole M.; Dickman, Chris R.; Du, Guozhen; Fay, Philip A.; Frater, Paul; Gruner, Daniel S.; Hagenah, Nicole; Hector, Andrew; Helm, Aveliina; Hillebrand, Helmut; Hofmockel, Kirsten S.; Humphries, Hope C.; Iribarne, Oscar; Jin, Virginia L.; Kay, Adam; Kirkman, Kevin P.; Klein, Julia A.; Knops, Johannes M.H.; La Pierre, Kimberly J.; Ladwig, Laura M.; Lambrinos; John, G.; Leakey, Andrew D.B.; Li, Qi; Li, Wei; McCulley, Rebecca; Melbourne, Brett; Mitchell; Charles, E.; Moore, Joslin L.; Morgan, John; Mortensen, Brent; O'Halloran, Lydia R.; Pärtel, Meelis; Pascual, Jesús; Pyke, David A.; Risch, Anita C.; Salguero-Gómez, Roberto; Sankaran, Mahesh; Schuetz, Martin; Simonsen, Anna; Smith, Melinda; Stevens, Carly; Sullivan, Lauren; Wardle, Glenda M.; Wolkovich, Elizabeth M.; Wragg, Peter D.; Wright, Justin; Yang, Louie
2013-01-01
Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species. Here, we used a globally replicated study to quantify relationships between exotic richness and abundance in grass-dominated ecosystems in 13 countries on six continents, ranging from salt marshes to alpine tundra. We tested effects of human land use, native community diversity, herbivore pressure, and nutrient limitation on exotic plant dominance. Despite its widespread use, exotic richness was a poor proxy for exotic dominance at low exotic richness, because sites that contained few exotic species ranged from relatively pristine (low exotic richness and cover) to almost completely exotic-dominated ones (low exotic richness but high exotic cover). Both exotic cover and richness were predicted by native plant diversity (native grass richness) and land use (distance to cultivation). Although climate was important for predicting both exotic cover and richness, climatic factors predicting cover (precipitation variability) differed from those predicting richness (maximum temperature and mean temperature in the wettest quarter). Herbivory and nutrient limitation did not predict exotic richness or cover. Exotic dominance was greatest in areas with low native grass richness at the site- or regional-scale. Although this could reflect native grass displacement, a lack of biotic resistance is a more likely explanation, given that grasses comprise the most aggressive invaders. These findings underscore the need to move beyond richness as a surrogate for the extent of invasion, because this metric confounds monodominance with invasion resistance. Monitoring
Stem cell mechanics: Auxetic nuclei
NASA Astrophysics Data System (ADS)
Wang, Ning
2014-06-01
The nuclei of naive mouse embryonic stem cells that are transitioning towards differentiation expand when the cells are stretched and contract when they are compressed. What drives this auxetic phenotype is, however, unclear.
Alpha Condensates in Atomic Nuclei
Suzuki, Y.; Matsumura, H.
2005-11-21
Recent issues on Bose-Einstein condensation (BEC) of {alpha}-particles in nuclei are reviewed. A candidate of condensates is discussed for some states in 12C and 16O by defining the amount of {alpha} condensation.
Biodiversity maintenance mechanisms differ between native and exotic communities
Technology Transfer Automated Retrieval System (TEKTRAN)
The ongoing homogenization of Earth’s biota is affecting nearly every region of the globe. Grasslands contain perhaps the most disrupted and homogenized communities. We studied 9-species plant communities containing all exotic (i.e. introduced) or all native species under controlled field conditio...
Regional collaborative research on cold tolerance of exotic biofuel grasses
Technology Transfer Automated Retrieval System (TEKTRAN)
Cold tolerance is a selectable trait for many exotic grasses, even those of tropical or subtropical origin. We are conducting cold tolerance assessments on an array of perennial biofuel grasses at Booneville, AR. In study one (published), we reported that two sugarcane clones (US84-1028 and US84-1...
Children Prioritize Virtual Exotic Biodiversity over Local Biodiversity
Ballouard, Jean-Marie; Brischoux, François; Bonnet, Xavier
2011-01-01
Environmental education is essential to stem current dramatic biodiversity loss, and childhood is considered as the key period for developing awareness and positive attitudes toward nature. Children are strongly influenced by the media, notably the internet, about biodiversity and conservation issues. However, most media focus on a few iconic, appealing, and usually exotic species. In addition, virtual activities are replacing field experiences. This situation may curb children knowledge and concerns about local biodiversity. Focusing our analyses on local versus exotic species, we examined the level of knowledge and the level of diversity of the animals that French schoolchildren are willing to protect, and whether these perceptions are mainly guided by information available in the internet. For that, we collected and compared two complementary data sets: 1) a questionnaire was administered to schoolchildren to assess their knowledge and consideration to protect animals, 2) an internet content analysis (i.e. Google searching sessions using keywords) was performed to assess which animals are the most often represented. Our results suggest that the knowledge of children and their consideration to protect animal are mainly limited to internet contents, represented by a few exotic and charismatic species. The identification rate of local animals by schoolchildren was meager, suggesting a worrying disconnection from their local environment. Schoolchildren were more prone to protect “virtual” (unseen, exotic) rather than local animal species. Our results reinforce the message that environmental education must also focus on outdoor activities to develop conservation consciousness and concerns about local biodiversity. PMID:21829710
Comparing native and exotic litter decomposition and nutrient dynamics.
Technology Transfer Automated Retrieval System (TEKTRAN)
Melaleuca quinquenervia is one of the most problematic invasive species in Florida Everglades’ ecosystem. Treatment of these populations has been justified in part by hypothesized changes in the rate of organic matter decomposition and nutrient release from exotic litter. This study investigated t...
Mechanisms underlying the impacts of exotic plant invasions.
Levine, Jonathan M; Vilà, Montserrat; D'Antonio, Carla M; Dukes, Jeffrey S; Grigulis, Karl; Lavorel, Sandra
2003-01-01
Although the impacts of exotic plant invasions on community structure and ecosystem processes are well appreciated, the pathways or mechanisms that underlie these impacts are poorly understood. Better exploration of these processes is essential to understanding why exotic plants impact only certain systems, and why only some invaders have large impacts. Here, we review over 150 studies to evaluate the mechanisms underlying the impacts of exotic plant invasions on plant and animal community structure, nutrient cycling, hydrology and fire regimes. We find that, while numerous studies have examined the impacts of invasions on plant diversity and composition, less than 5% test whether these effects arise through competition, allelopathy, alteration of ecosystem variables or other processes. Nonetheless, competition was often hypothesized, and nearly all studies competing native and alien plants against each other found strong competitive effects of exotic species. In contrast to studies of the impacts on plant community structure and higher trophic levels, research examining impacts on nitrogen cycling, hydrology and fire regimes is generally highly mechanistic, often motivated by specific invader traits. We encourage future studies that link impacts on community structure to ecosystem processes, and relate the controls over invasibility to the controls over impact. PMID:12737654
PAMELA/ATIC anomaly from exotic mediated dark matter decay
NASA Astrophysics Data System (ADS)
Bae, Kyu Jung; Kyae, Bumseok
2009-05-01
We discuss dark matter decay mediated by exotically charged particles (``exotics'') in a supersymmetric model with two dark matter (DM) components: one is the (bino-like) lightest supersymmetric particle (LSP) χ, and the other is a newly introduced meta-stable neutral singlet N. N decays to χe+e- via a dimension 6 operator induced by a penguin-type one loop diagram with the life time of 1026 sec., explaining energetic cosmic e± excess observed recently by PAMELA and ATIC/PPB-BETS. The superheavy masses of exotics ( ~ 1015-16 GeV) are responsible for the longevity of N. The superpartner of N develops the vacuum expectation value (VEV) of order TeV so that the DM N achieves the desired mass of 2 TeV. By the VEV, the U(1)R symmetry is broken to the discrete Z2 symmetry, which is identified with the matter parity in the minimal supersymmetric standard model (MSSM). Since we have the two DM components, even extremely small amount of N [Script O(10-10) lesssim (nN/nχ)] could account for the observed positron flux with relatively light exotics' masses [1012 GeV lesssim Mexo lesssim 1016 GeV].
Searches for exotic interactions in nuclear beta decay
NASA Astrophysics Data System (ADS)
Naviliat-Cuncic, O.
2016-07-01
This contribution presents current efforts in the search for exotic interactions in nuclear β decay using a calorimetric technique for the measurement of the β energy spectrum shape. We describe the criteria for the choice of sensitive candidates in Gamow-Teller transitions and present the status of measurements performed in 6He and 20F decay.
Research update on exotic and emerging poultry diseases
Technology Transfer Automated Retrieval System (TEKTRAN)
Exotic and emerging diseases of poultry continue to be a threat to US poultry. Studies over the past year have demonstrated: 1) cooking poultry meat at minimum of 70C kills avian influenza (AI) and Newcastle disease (ND) viruses in a few seconds, 2) low pathogenicity (LP) AI viruses isolated from fr...
Phenology of exotic invasive weeds associated with downy brome
Technology Transfer Automated Retrieval System (TEKTRAN)
The exotic and highly invasive annual grass downy brome (Bromus tectorum) has invaded millions of hectares of rangelands throughout the Intermountain West. Downy brome increases the chance, rate, season and spread of wildfires, resulting in the destruction of native plant communities and the wildli...
Generalized parton distributions in nuclei
Vadim Guzey
2009-12-01
Generalized parton distributions (GPDs) of nuclei describe the distribution of quarks and gluons in nuclei probed in hard exclusive reactions, such as e.g. deeply virtual Compton scattering (DVCS). Nuclear GPDs and nuclear DVCS allow us to study new aspects of many traditional nuclear effects (nuclear shadowing, EMC effect, medium modifications of the bound nucleons) as well as to access novel nuclear effects. In my talk, I review recent theoretical progress in the area of nuclear GPDs.
NASA Technical Reports Server (NTRS)
Sykes, Mark V.; Walker, Russell G.
1992-01-01
The icy-conglomerate model of comet nuclei has dominated all others since its introduction. It provided a basis for understanding the non-gravitational motions of comets which had perplexed dynamicists up to that time, and provided a focus for understanding cometary composition and origin. The image of comets as dirty snowballs was quickly adopted. Comet nuclei including their trail mass loss rates and refractory to volatile mass ratios are described.
Manifestation of cluster effects in collective octupole and superdeformed states of heavy nuclei.
NASA Astrophysics Data System (ADS)
Shneidman, T. M.; Adamian, G. G.; Antonenko, N. V.; Jolos, R. V.
2016-06-01
The effects of reflection-asymmetric deformation on the properties of the low-lying negative-parity collective states and superdeformed states of heavy nuclei are analyzed basing on dinuclear model. The results of consideration of the alternating parity bands in actinides and the superdeformed bands in 60Zn, Pb and Hg isotopes are discussed.
ALERT I and II: Hauser Feshbach codes for nuclei at high excitation and angular momenta
Blann, M; Komoto, T A
1982-05-01
A description is given of two versions of a Hauser Feshbach code descended from the MBII code. The level density options, which include collective enhancement options, modeling of transmission coefficients for deformed nuclei, and fission barrier options are discussed in some detail. A listing of the codes, plus sample input and output are appended.
NASA Astrophysics Data System (ADS)
Spirito, Florencia; Yahdjian, Laura; Tognetti, Pedro M.; Chaneton, Enrique J.
2014-01-01
Old fields often become dominated by exotic plants establishing persistent community states. Ecosystem functioning may differ widely between such novel communities and the native-dominated counterparts. We evaluated soil ecosystem attributes in native and exotic (synthetic) grass assemblages established on a newly abandoned field, and in remnants of native grassland in the Inland Pampa, Argentina. We asked whether exotic species alter soil functioning through the quality of the litter they shed or by changing the decomposition environment. Litter decomposition of the exotic dominant Festuca arundinacea in exotic assemblages was faster than that of the native dominant Paspalum quadrifarium in native assemblages and remnant grasslands. Decomposition of a standard litter (Triticum aestivum) was also faster in exotic assemblages than in native assemblages and remnant grasslands. In a common garden, F. arundinacea showed higher decay rates than P. quadrifarium, which reflected the higher N content and lower C:N of the exotic grass litter. Soil respiration rates were higher in the exotic than in the native assemblages and remnant grasslands. Yet there were no significant differences in soil N availability or net N mineralization between exotic and native assemblages. Our results suggest that exotic grass dominance affected ecosystem function by producing a more decomposable leaf litter and by increasing soil decomposer activity. These changes might contribute to the extended dominance of fast-growing exotic grasses during old-field succession. Further, increased organic matter turnover under novel, exotic communities could reduce the carbon storage capacity of the system in the long term.
Risk of exotic annual grass-fire cycle in Goose Creek milkvetch habitat
Technology Transfer Automated Retrieval System (TEKTRAN)
There is a concern that habitats surrounding Goose Creek milkvetch populations are at risk of exotic annual grass invasion leading to an exotic annual grass-fire cycle. We sampled plant community and site characteristics to evaluate the risk of these habitats developing an exotic annual grass-fire ...
Dinucleon correlation enhancement in p-shell nuclei
NASA Astrophysics Data System (ADS)
Kobayashi, Fumiharu; Kanada-En'yo, Yoshiko
2014-09-01
Dinucleon (dineutron or diproton) correlation is one of the most attractive phenomena in the physics of unstable nuclei. A dinucleon is a pair of two nucleons coupled to spin-singlet having a strong spatial correlation, considered to be a bosonic cluster. Dinucleon correlation would be significant for the description of the valence nucleon motion at the nuclear surface of unstable nuclei. To clarify the formation mechanism and the universal properties of dinucleon correlation, we have constructed a framework of dinucleon condensate (DC) wave function, which can describe the detailed dinucleon motion around a core which can be deformed and excited. In this work, we use the antisymmetrized molecular dynamics (AMD) wave functions and the DC wave functions to analyze the effect of the core structure, especially the occupied orbits by the core nucleons, on dinucleon formation in p-shell neutron-rich and proton-rich nuclei (e.g. neutron-rich Li isotopes and proton-rich O isotones). We will show that the LS-favored 0p3 / 2 orbits play an important role to dissociate dinucleon components to j- j coupling shell-model components without spatial correlation and that the occupation probability of 0p3 / 2 would be a key to the enhancement of dinucleon correlation in p-shell nuclei.
Effective valence proton numbers for nuclei with Z˜64
NASA Astrophysics Data System (ADS)
Fu, G. J.; Jiang, H.; Zhao, Y. M.; Arima, A.
2011-09-01
The subshell effect for nuclei with proton number Z˜ 64 has been known for many years. The most economic way to consider this effect is to use the effective valence proton number. In this Brief Report we extract effective valence proton numbers for nuclei in this region by using the systematics of the first 2+ energies (E21+) of even-even nuclei, the ratios of the first 4+ and 6+ state energies with respect to E21+ (R4 and R6), the B(E2) values, the quadrupole deformation parameters e2, and anomalous g factors of the 21+ state for even-even nuclei. It is noticed that these physical quantities saturate when NpNn, the product of the valence proton number and the valence neutron number, is large enough; on the other hand, they go to saturation at different “speeds.” We show that the subshell effect is more evident for E21+ and yrast state energy ratios (R4 and R6), and relatively less for other quantities.
NASA Technical Reports Server (NTRS)
Clark, T. A.; Thomsen, P.
1988-01-01
A study is presented of deformations in antennas with the emphasis on their influence on VLBI measurements. The GIFTS structural analysis program has been used to model the VLBI antenna in Fairbanks (Alaska). The report identifies key deformations and studies the effect of gravity, wind, and temperature. Estimates of expected deformations are given.
Microscopic derivation of IBM and structural evolution in nuclei
Nomura, Kosuke
2011-05-06
A Hamiltonian of the interacting boson model (IBM) is derived based on the mean-field calculations with nuclear energy density functionals (EDFs). The multi-nucleon dynamics of the surface deformation is simulated in terms of the boson degrees of freedom. The interaction strengths of the IBM Hamiltonian are determined by mapping the potential energy surfaces (PESs) of a given EDF with quadrupole degrees of freedom onto the corresponding PES of IBM. A fermion-to-boson mapping for a rotational nucleus is discussed in terms of the rotational response, which reflects a specific time-dependent feature. Ground-state correlation energy is evaluated as a signature of structural evolution. Some examples resulting from the present spectroscopic calculations are shown for neutron-rich Pt, Os and W isotopes including exotic ones.
Binding energies of even-even superheavy nuclei in a semi-microscopic approach
Ismail, M.; Ellithi, A. Y.; Botros, M. M.; Adel, A.
2010-10-15
The structure of some even-even superheavy nuclei with the proton number Z = 98-120 is studied using a semi-microscopic but not self-consistent model. The macroscopic energy part is obtained from the Skyrme nucleon-nucleon interaction in the semi-classical extended Thomas-Fermi approach. A simple but accurate method is derived for calculating the direct part of the Coulomb energy. The microscopic shell plus pairing energy corrections are calculated from the traditional Strutinsky method. Within this semi-microscopic approach, the total energy curves with the quadrupole deformation of the studied superheavy nuclei were calculated. The same approach features the well known {sup 208}Pb or {sup 238}U nuclei. For each nucleus the model predictions for the binding energy, the deformation parameters, the half-density radii and comparison with other theoretical models are made. The calculated binding energies are in good agreement with the available experimental data.
Precision mass measurements of neutron halo nuclei using the TITAN Penning trap
NASA Astrophysics Data System (ADS)
Brodeur, M.; Brunner, T.; Ettenauer, S.; Gallant, A. T.; Simon, V. V.; Smith, M.; Lapierre, A.; Mané, E.; Ringle, R.; Ryjkov, V. L.; Bacca, S.; Delheij, P.; Lunney, D.; Pearson, M.; Dilling, J.
2011-07-01
Precise atomic mass determinations play a key role in various fields of physics, including nuclear physics, testing of fundamental symmetries and constants and atomic physics. Recently, the TITAN Penning trap measured the masses of several neutron halos. These exotic systems have an extended, diluted, matter distribution that can be modelled by considering a nuclear core surrounded by a halo formed by one or more of loosely bound neutrons. Combined with laser spectroscopy measurements of isotopic shifts precise masses can be used to obtain reliable charge radii and two-neutron-seperation energies for these halo nuclei. It is shown that these results can be used as stringent tests of nuclear models and potentials providing an important metric for our understanding of the interactions in all nuclei.
Cluster-transfer reactions with radioactive beams: A spectroscopic tool for neutron-rich nuclei
NASA Astrophysics Data System (ADS)
Bottoni, S.; Leoni, S.; Fornal, B.; Raabe, R.; Rusek, K.; Benzoni, G.; Bracco, A.; Crespi, F. C. L.; Morales, A. I.; Bednarczyk, P.; Cieplicka-Oryńczak, N.; Królas, W.; Maj, A.; Szpak, B.; Callens, M.; Bouma, J.; Elseviers, J.; De Witte, H.; Flavigny, F.; Orlandi, R.; Reiter, P.; Seidlitz, M.; Warr, N.; Siebeck, B.; Hellgartner, S.; Mücher, D.; Pakarinen, J.; Vermeulen, M.; Bauer, C.; Georgiev, G.; Janssens, R. V. F.; Balabanski, D.; Sferrazza, M.; Kowalska, M.; Rapisarda, E.; Voulot, D.; Lozano Benito, M.; Wenander, F.
2015-08-01
An exploratory experiment performed at REX-ISOLDE to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The reactions 7Li(98Rb,α xn ) and 7Li(98Rb,t xn ) were studied through particle-γ coincidence measurements, and the results are presented in terms of the observed excitation energies and spins. Moreover, the reaction mechanism is qualitatively discussed as a transfer of a clusterlike particle within a distorted-wave Born approximation framework. The results indicate that cluster-transfer reactions can be described well as a direct process and that they can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.
Semiclassical treatment of fusion and breakup processes of ^{6,8}He halo nuclei
NASA Astrophysics Data System (ADS)
Majeed, Fouad A.; Abdul-Hussien, Yousif A.
2016-06-01
A semiclassical approach has been used to study the effect of channel coupling on the calculations of the total fusion reaction cross section σ _{fus}, and the fusion barrier distribution D_{fus} for the systems 6He +^{238}U and 8He +^{197}Au. Since these systems invloves light exotic nuclei, breakup states channel play an important role that should be considered in the calculations. In semiclassical treatment, the relative motion between the projectile and target nuclei is approximated by a classical trajectory while the intrinsic dynamics is handled by time-dependent quantum mechanics. The calculations of the total fusion cross section σ _{fus}, and the fusion barrier distribution D_{fus} are compared with the full quantum mechanical calculations using the coupled-channels calculations with all order coupling using the computer code and with the available experimental data.
GDR as a Probe of the Collective Motion in Nuclei at High Spins, Temperatures or Isospins
Maj, Adam
2008-11-11
The gamma-decay of the Giant Dipole Resonance (GDR), the high-frequency collective vibration of protons against neutrons, has been proven to be a basic probe for the shapes of hot nuclei, especially to study the effective shape evolution caused by the collective rotation of a nucleus. In this context an interesting question arises: what is the nuclear shape at extreme values of spin or temperatures, close to the limit impose by another collective motion--fission, and how evolves the giant dipole collective vibrations as a function of isospin. Short overview of the results from the experiments aimed to answer these questions are presented and possible perspectives of these type of studies for exotic nuclei to be obtained with the novel gamma-calorimeter PARIS and soon available intense radioactive beams are discussed.
Theory of band comparison in even-even nuclei
NASA Astrophysics Data System (ADS)
Buck, B.; Merchant, A. C.; Perez, S. M.
2003-08-01
We previously found that a cluster model reproduces satisfactorily the properties of normal deformed (ND) ground state and superdeformed (SD) excited bands in a wide range of even-even nuclei. We show here that the fractional change of the transition energies in two bands described by similar core-cluster configurations is closely related to the fractional change in the corresponding reduced masses. We compare our predictions to data on ground state ND bands for a series of light rare-earth and actinide isotopes, and on SD bands in the A˜150 and 190 regions. The model strongly suggests the existence of similar excited SD bands in 212Pb and 212Po, in addition to the observed α-cluster-like ND ground state bands of these nuclei.
Fission barriers for even-even superheavy nuclei
Kowal, M.; Sobiczewski, A.; Jachimowicz, P.
2010-07-15
A quantitative model for the evaluation of the heights of static fission barriers is formulated within the framework of the macroscopic-microscopic approach. In order to describe the main properties (at the ground state and at the saddle point) of superheavy nuclei, a high-dimensional deformation space is used. In the present paper we systematically calculate fission barrier heights B{sub f} for even-even heavy and superheavy nuclei in the range of proton numbers 92<=Z<=126 and neutron numbers 134<=N<=192. Comparisons with experimental data and different theoretical calculations are also shown. The dependence on B{sub f} of fully incorporated, nonaxiality, and reflection-asymmetric degrees of freedom is discussed.
Collision dynamics of two 238U atomic nuclei.
Golabek, Cédric; Simenel, Cédric
2009-07-24
Collisions of actinide nuclei form, during very short times of few 10;{-21} s, the heaviest ensembles of interacting nucleons available on Earth. Such collisions have been proposed as an alternative way to produce heavy and superheavy elements. They are also used to produce superstrong electric fields by the huge number of interacting protons to test spontaneous positron-electron (e;{+}e;{-}) pair emission predicted by the quantum electrodynamics theory. The time-dependent Hartree-Fock theory is used to study collision dynamics of two 238U atomic nuclei. In particular, the role of nuclear deformation on collision time and on reaction mechanisms such as nucleon transfer is emphasized. The highest collision times (approximately 4 x 10;{-21} s at 1200 MeV) should allow experimental signature of spontaneous e;{+}e;{-} emission in case of bare uranium ions. Surprisingly, we also observe ternary fission due to purely dynamical effects. PMID:19659346
Collision Dynamics of Two {sup 238}U Atomic Nuclei
Golabek, Cedric; Simenel, Cedric
2009-07-24
Collisions of actinide nuclei form, during very short times of few 10{sup -21} s, the heaviest ensembles of interacting nucleons available on Earth. Such collisions have been proposed as an alternative way to produce heavy and superheavy elements. They are also used to produce superstrong electric fields by the huge number of interacting protons to test spontaneous positron-electron (e{sup +}e{sup -}) pair emission predicted by the quantum electrodynamics theory. The time-dependent Hartree-Fock theory is used to study collision dynamics of two {sup 238}U atomic nuclei. In particular, the role of nuclear deformation on collision time and on reaction mechanisms such as nucleon transfer is emphasized. The highest collision times (approx4x10{sup -21} s at 1200 MeV) should allow experimental signature of spontaneous e{sup +}e{sup -} emission in case of bare uranium ions. Surprisingly, we also observe ternary fission due to purely dynamical effects.
Role of shapes in the identification of superheavy nuclei
Shanmugam, G.; Sudhakar, S.; Niranjani, S.
2005-09-01
The synthesis and identification of superheavy nuclei have taken a dramatic turn recently with the emergence of hot fusion reactions. Such new methods have enabled the synthesis and identification of superheavy elements with Z=114-116 and 118. The identification of such elements is mainly done by observing their {alpha}-decay chains terminating with spontaneous fission events. In such studies, the role played by the shapes of superheavy elements has assumed great significance. In this work, we use the Shanmugam-Kamalaharan model for {alpha} decay, which is versatile in accounting for the shapes and deformations of the parent and the daughter nuclei as well as the charge redistribution (also termed charge equilibration) process during the decay. Our calculations turn out to be very useful for the identification of superheavy elements.
Evidence for partial dynamical symmetries in atomic nuclei.
Casten, R F; Cakirli, R B; Blaum, K; Couture, A
2014-09-12
Symmetries in nature offer very simple descriptions of complex systems. Partial Dynamical Symmetries (PDS) can considerably broaden their relevance. To present the first extensive test of a PDS for nuclei, we compare an SU(3) PDS to gamma to ground band B(E2) values for 47 deformed nuclei. The parameter-free PDS is found to be quite successful, but with characteristic discrepancies, suggesting that symmetry remnants are more pervasive than heretofore realized. Furthermore, the SU(3) PDS gives new insights into collective models (e.g., interacting boson approximation). If these reproduce the PDS, they reflect finite size effects, while differences from the PDS point to SU(3) configuration mixing. PMID:25259972
Ultra-High Spin Spectroscopy In Er Nuclei
NASA Astrophysics Data System (ADS)
Simpson, J.
2008-11-01
The discoveries observed in the ongoing conflict between collective and single-particle nuclear behaviour with increasing angular momentum have driven the field of nuclear spectroscopy for many decades and have given rise to new nuclear phenomena. Recently a new frontier of γ spectroscopy at ultra-high spin has been opened in the rare-earth region with rotational bands that bypass the classic band-terminating states that appear at spin 45ℏ in the N 90 Er nuclei. These weakly populated rotational structures have characteristics of triaxial strongly-deformed bands. Such structures have been observed in 157,158,160Er, following a series of experiments using the Gammasphere spectrometer. These observations herald a return to collective excitations at spins of about 50 to 65ℏ. This talk reviews the status of the spectroscopy and understanding of the observed structures in these Er and neighbouring nuclei.
Shape phase transitions in odd-A nuclei
Alonso, C. E.; Arias, J. M.; Fortunato, L.; Vitturi, A.
2008-11-11
We investigate shape phase transitions in odd nuclei within the Interacting Boson Fermion Model. Special attention is given to the case of the transition from the vibrational behaviour to the stable axial deformation. The odd particle is assumed to be moving in the three single particle orbitals j = 1/2,3/2,5/2 with a boson-fermion Hamiltonian that leads to the occurrence of the SU{sup BF}(3) boson-fermion symmetry when the boson part approaches the SU(3) condition. Both energy spectra and electromagnetic transitions show characteristic patterns similar to those displayed by the even nuclei at the corresponding critical point. The role of the additional particle in characterizing the properties of the critical points in finite quantal systems is investigated by resorting to the formalism based on the intrinsic frame.
Ultra-High Spin Spectroscopy In Er Nuclei
Simpson, J.
2008-11-11
The discoveries observed in the ongoing conflict between collective and single-particle nuclear behaviour with increasing angular momentum have driven the field of nuclear spectroscopy for many decades and have given rise to new nuclear phenomena. Recently a new frontier of {gamma} spectroscopy at ultra-high spin has been opened in the rare-earth region with rotational bands that bypass the classic band-terminating states that appear at spin 45({Dirac_h}/2{pi}) in the N 90 Er nuclei. These weakly populated rotational structures have characteristics of triaxial strongly-deformed bands. Such structures have been observed in {sup 157,158,160}Er, following a series of experiments using the Gammasphere spectrometer. These observations herald a return to collective excitations at spins of about 50 to 65({Dirac_h}/2{pi}). This talk reviews the status of the spectroscopy and understanding of the observed structures in these Er and neighbouring nuclei.
NASA Astrophysics Data System (ADS)
Afanasjev, A. V.; Abdurazakov, O.
2013-07-01
The cranked relativistic Hartree-Bogoliubov theory has been applied for a systematic study of pairing and rotational properties of actinides and light superheavy nuclei. Pairing correlations are taken into account by the Brink-Booker part of finite-range Gogny D1S force. For the first time, in the covariant density functional theory (CDFT) framework, the pairing properties of deformed nuclei are studied via the quantities (such as three-point Δ(3) indicators) related to odd-even mass staggerings. The investigation of the moments of inertia at low spin and the Δ(3) indicators shows the need for an attenuation of the strength of the Brink-Booker part of the Gogny D1S force in pairing channel. The investigation of rotational properties of even-even and odd-mass nuclei at normal deformation, performed in the density functional theory framework in such a systematic way for the first time, reveals that in the majority of the cases the experimental data are well described. These include the evolution of the moments of inertia with spin, band crossings in the A≥242 nuclei, the impact of the particle in specific orbital on the moments of inertia in odd-mass nuclei. The analysis of the discrepancies between theory and experiment in the band crossing region of A≤240 nuclei suggests the stabilization of octupole deformation at high spin, not included in the present calculations. The evolution of pairing with deformation, which is important for the fission barriers, has been investigated via the analysis of the moments of inertia in the superdeformed minimum. The dependence of the results on the CDFT parametrization has been studied by comparing the results of the calculations obtained with the NL1 and NL3* parametrizations.
Deformable Nanolaminate Optics
Olivier, S S; Papavasiliou, A P; Barbee, T W; Miles, R R; Walton, C C; Cohn, M B; Chang, K
2006-05-12
We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces.
The α decay spectroscopic factor of heavy and superheavy nuclei
NASA Astrophysics Data System (ADS)
Seif, W. M.
2013-10-01
The spectroscopic factor which refers to the preformation probability of an α cluster inside parent radioactive nuclei is investigated. The study is based on the cluster model of α decay that is extended to account for the deformation degrees of freedom. The calculations are carried out for 179 even(Z)-even(N) parent nuclei in the mass region of A = 144-294. Taking into account the deformations of daughter nuclei, the semi-microscopic calculations of the α-daughter interaction potential are performed using the Hamiltonian energy density approach in terms of the SLy4 Skyrme-like effective interaction. The calculated potential is then implemented to find both the assault frequency and the penetration probability of the α particle by means of the Wentzel-Kramers-Brillouin approximation at different orientations of the deformed daughter. By averaging the obtained decay widths over different orientations, the half-lives of the mentioned α decays are then estimated. Taking into account the errors on both the released energy and the experimental half-life times, the extracted half-lives are employed in turn to deduce the α spectroscopic factor. The results show a periodic behaviour of the spectroscopic factor as a function of the charge and neutron numbers characterized by several local maxima and minima. The predicted minima are mainly related to the proton and neutron shell and subshell closures. In addition to the well-known closed shells of the nucleonic numbers 50, 82, and 126, the obtained values of the spectroscopic factor give some evidence for the presence of closed subshells of nucleonic numbers 70, 102 (104) and 152 (150). A simple formula is suggested to roughly estimate the spectroscopic factor in terms of the numbers of protons and neutrons of the parent nucleus outside its closed shells. The parameters of this formula are fitted to the deduced values of the spectroscopic factor.
NASA Astrophysics Data System (ADS)
Rubio, B.; Orrigo, S. E. A.; Kucuk, L.; Montaner-Pizá, A.; Fujita, Y.; Fujita, H.; Blank, B.; Gelletly, W.; Adachi, T.; Agramunt, J.; Algora, A.; Ascher, P.; Bilgier, B.; Cáceres, L.; Cakirli, R. B.; de France, G.; Ganioğlu, E.; Gerbaux, M.; Giovinazzo, J.; Grevy, S.; Kamalou, O.; Kozer, H. C.; Kurtukian-Nieto, T.; Marqués, F. M.; Molina, F.; Oktem, Y.; de Oliveira Santos, F.; Perrot, L.; Popescu, L.; Raabe, R.; Rogers, A. M.; Srivastava, P. C.; Susoy, G.; Suzuki, T.; Tamii, A.; Thomas, J. C.
2014-06-01
This paper concerns the experimental study of the β decay properties of few proton-rich fp-shell nuclei. The nuclei were produced at GANIL in fragmentation reactions, separated with the LISE spectrometer and stopped in an implantation detector surrounded by Ge detectors. The β-delayed gammas, β-delayed protons and the exotic β-delayed gamma-proton emission have been studied. Preliminary results are presented. The decay of the Tz = - 2 nucleus 56Zn has been studied in detail. Information from the β-delayed protons and β-delayed gammas has been used to deduce the decay scheme. The exotic beta-delayed gamma-proton decay has been observed for the first time in the fp-shell. The interpretation of the data was made possible thanks to the detailed knowledge of the mirror Charge Exchange (CE) process and the gamma de-excitation of the states in 56Co, the mirror nucleus of 56Cu.
Reflection-asymmetric rotor model of odd Aapprox. 219--229 nuclei
Leander, G.A.; Chen, Y.S.
1988-06-01
The low-energy spectroscopy of odd-A nuclei in the mass region Aapprox.219--229 is modeled by coupling states of a deformed shell model including octupole deformation to a reflection-asymmetric rotor core. Theory and experiment are compared for the nuclei in which data are available: /sup 219,221,223,225/Rn, /sup 221,223,225,227/Fr, /sup 219,221,223,225,227/Ra, /sup 219,223,225,227,229/Ac /sup 221,223,225,227,229/Th, and /sup 229/Pa. Overall agreement requires an octupole deformation ..beta../sub 3/approx.0.1. The results throughout the region are synthesized to evaluate the model.
Experimental level-structure determination in odd-odd actinide nuclei
Hoff, R.W.
1985-04-04
The status of experimental determination of level structure in odd-odd actinide nuclei is reviewed. A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei is applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation are derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings are used. Calculated and experimental level structures for /sup 238/Np, /sup 244/Am, and /sup 250/Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Applications of this modeling technique are discussed.
The Alternative Scheme to Describe Nuclei with X(5) Symmetry
NASA Astrophysics Data System (ADS)
Dai, L. R.; Pan, F.; Liu, R. L.; Yu, H.; Zhang, W. L.
The possible nuclei with X(5) symmetry are investigated in the Interacting Boson Model (IBM), in which the traditional scheme and a new alternative scheme from the spherical to the axially deformed limit of the IBM with a schematic Hamiltonian are studied by using the SU(3) quadrupole-quadrupole term and O(6) cubic interaction, respectively. The low-lying energy levels and E2 transition rates from the new scheme are calculated and compared with the experimental data and those of the traditional U(5) - SU(3) description. It is shown that the results from this new scheme seem better than those of the traditional description.
Cavitation inception from bubble nuclei.
Mørch, K A
2015-10-01
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, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model 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. PMID:26442138
Photodissociation of neutron deficient nuclei
NASA Astrophysics Data System (ADS)
Sonnabend, K.; Babilon, M.; Hasper, J.; Müller, S.; Zarza, M.; Zilges, A.
2006-03-01
The knowledge of the cross sections for photodissociation reactions like e.g. (γ, n) of neutron deficient nuclei is of crucial interest for network calculations predicting the abundances of the so-called p nuclei. However, only single cross sections have been measured up to now, i.e., one has to rely nearly fully on theoretical predictions. While the cross sections of stable isotopes are accessible by experiments using real photons, the bulk of the involved reactions starts from unstable nuclei. Coulomb dissociation (CD) experiments in inverse kinematics might be a key to expand the experimental database for p-process network calculations. The approach to test the accuracy of the CD method is explained.
Polarized EMC Effect in Nuclei
Ian Cloet; A. W. Thomas; W. Bentz
2006-06-05
The discovery of the EMC effect and the proton spin crisis by the European Muon Collaboration are two of the standout experiments of the last 25 years. It is therefore surprising that there has been no experimental and little theoretical investigation of the spin structure functions of atomic nuclei. To address this we present results for the spin-dependent structure functions of nuclei. The quark degrees of freedom in nuclei are accessed via the convolution formalism. Where the nucleon bound state is obtained by solving the relativistic Faddeev equation, and a relativistic shell model is used to model the atomic nucleus. We find the important result that the medium modifications to the polarized structure functions are about twice that of the unpolarized case.